業績情報

• The deficiency of methylglyoxal synthase promotes cell proliferation in Synechocystis sp. PCC 6803 under mixotrophic conditions　　　　　　　　　　　　　　　
  Aikeranmu Kadeer; Yuuma Ishikawa; Kaushalya Dayarathne; Atsuko Miyagi; Toshiki Ishikawa; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Plant Biotechnology, 巻：41, 号：4, 開始ページ：393, 終了ページ：399, 2024年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.24.0718a
  DOI ID：10.5511/plantbiotechnology.24.0718a
• Production of extracellular superoxide contributes to photosynthesis via elimination of reducing power and regeneration of NADP+ in the red-tide-forming raphidophyte Chattonella marina complex　　　　　　　　　　　　　　　
  Koki Yuasa; Takayoshi Ichikawa; Yuma Ishikawa; Haruhiko Jimbo; Maki Kawai-Yamada; Tomoyuki Shikata; Yoshitaka Nishiyama
  Harmful Algae, 巻：139, 開始ページ：102712, 終了ページ：102712, 2024年11月, ［査読有り］
  Elsevier BV, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.hal.2024.102712
  DOI ID：10.1016/j.hal.2024.102712, ISSN：1568-9883
• Arabidopsis DREB26/ERF12 and its close relatives regulate cuticular wax biosynthesis under drought stress condition
  Kaoru Urano; Yoshimi Oshima; Toshiki Ishikawa; Takuma Kajino; Shingo Sakamoto; Mayuko Sato; Kiminori Toyooka; Miki Fujita; Maki Kawai‐Yamada; Teruaki Taji; Kyonoshin Maruyama; Kazuko Yamaguchi‐Shinozaki; Kazuo Shinozaki
  The Plant Journal, 巻：120, 号：5, 開始ページ：2057, 終了ページ：2075, 2024年10月, ［査読有り］
  SUMMARY
  
  Land plants have evolved a hydrophobic cuticle on the surface of aerial organs as an adaptation to ensure survival in terrestrial environments. Cuticle is mainly composed of lipids, namely cutin and intracuticular wax, with epicuticular wax deposited on plant surface. The composition and permeability of cuticle have a large influence on its ability to protect plants against drought stress. However, the regulatory mechanisms underlying cuticular wax biosynthesis in response to drought stress have not been fully elucidated. Here, we identified three AP2/ERF transcription factors (DREB26/ERF12, ERF13 and ERF14) involved in the regulation of water permeability of the plant surface. Transmission electron microscopy revealed thicker cuticle on the leaves of DREB26‐overexpressing (DREB26OX) plants, and thinner cuticle on the leaves of transgenic plants expressing SRDX repression domain‐fused DREB26 (DREB26SR). Genes involved in cuticular wax formation were upregulated in DREB26OX and downregulated in DREB26SR. The levels of very‐long chain (VLC) alkanes, which are a major wax component, increased in DREB26OX leaves and decreased in DREB26SR leaves. Under dehydration stress, water loss was reduced in DREB26OX and increased in DREB26SR. The erf12/13/14 triple mutant showed delayed growth, decreased leaf water content, and reduced drought‐inducible VLC alkane accumulation. Taken together, our results indicate that the DREB26/ERF12 and its closed family members, ERF13 and ERF14, play an important role in cuticular wax biosynthesis in response to drought stress. The complex transcriptional cascade involved in the regulation of cuticular wax biosynthesis under drought stress conditions is discussed.
  Wiley, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.17100
  DOI ID：10.1111/tpj.17100, ISSN：0960-7412, eISSN：1365-313X
• The effect of light availability and light wavelength on growth, 2-MIB biosynthesis, and 2-MIB-related gene expression in Pseudanabaena foetida var. intermedia.　　　　　　　　　　　　　　　
  Kaushalya Dayarathne; Toshiki Ishikawa; Aikeranmu Kadeer; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Archives of microbiology, 巻：206, 号：9, 開始ページ：367, 終了ページ：367, 2024年08月, ［査読有り］, ［国際誌］
  2-methylisoborneol (2-MIB) is an odiferous metabolite mainly produced by cyanobacteria, contributing to taste and odor problems in drinking water. The mechanisms involved in 2-MIB biosynthesis in cyanobacteria are not yet completely understood. This study investigated the effect of light availability and wavelength on growth, 2-MIB synthesis, and related gene expression in Pseudanabaena foetida var. intermedia. A significantly lower 2-MIB production was observed in P. foetida var. intermedia during the dark period of a 12-h photoperiod. Exposure to green light resulted in a significant decrease in 2-MIB production compared to white light and red light. The relative expression levels of 2-MIB-related genes in P. foetida var. intermedia were significantly lower during the dark period of a 12-h photoperiod and when cultured under green light. The expression of 2-MIB-related genes in cyanobacteria appears to be light-dependent. This study suggests that the demand for photopigment synthesis under unfavorable light conditions affects the 2-MIB synthesis in cyanobacteria.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00203-024-04099-w
  DOI ID：10.1007/s00203-024-04099-w, PubMed ID：39105810
• Metabolic diversity analysis and genome wide assessment of oxalate accumulation in the leaves of rice Oryza sativa cultivars
  Atsuko Miyagi; Nobuhiro Tanaka; Matthew Shenton; Kaworu Ebana; Satoshi Ohkubo; Shunsuke Adachi; Taiichiro Ookawa; Maki Kawai-Yamada
  Plant Biotechnology, 巻：41, 開始ページ：1, 終了ページ：7, 2024年03月, ［査読有り］
  Japanese Society for Plant Cell and Molecular Biology, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.23.1025a
  DOI ID：10.5511/plantbiotechnology.23.1025a, ISSN：1342-4580, eISSN：1347-6114
• Adjustment of light-responsive NADP dynamics in chloroplasts by stromal pH
  Yusuke Fukuda; Chinami Ishiyama; Maki Kawai-Yamada; Shin-nosuke Hashida
  Nature Communications, 巻：14, 号：1, 2023年11月, ［査読有り］
  Abstract
  
  Cyclic electron transfer (CET) predominates when NADP⁺ is at basal levels, early in photosynthetic induction; however, the mechanism underlying the subsequent supply of NADP⁺ to fully drive steady-state linear electron transfer remains unclear. Here, we investigated whether CET is involved in de novo NADP⁺ supply in Arabidopsis thaliana and measured chloroplastic NADP dynamics to evaluate responsiveness to variable light, photochemical inhibitors, darkness, and CET activity. The sum of oxidized and reduced forms shows that levels of NADP and NAD increase and decrease, respectively, in response to light; levels of NADP and NAD decrease and increase in the dark, respectively. Moreover, consistent with the pH change in the stroma, the pH preference of chloroplast NAD⁺ phosphorylation and NADP⁺ dephosphorylation is alkaline and weakly acidic, respectively. Furthermore, CET is correlated with upregulation of light-responsive NADP level increases and downregulation of dark-responsive NADP level reductions. These findings are consistent with CET helping to regulate NADP pool size via stromal pH regulation under fluctuating light conditions.
  Springer Science and Business Media LLC, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1038/s41467-023-42995-9
  DOI ID：10.1038/s41467-023-42995-9, eISSN：2041-1723, ORCID：146070222
• MHP1 and MHL generate odd-chain fatty acids from 2-hydroxy fatty acids in sphingolipids and are related to immunity in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Marina Ushio; Toshiki Ishikawa; Takakazu Matsuura; Izumi C. Mori; Maki Kawai-Yamada; Yoichiro Fukao; Minoru Nagano
  Plant Science, 巻：336, 開始ページ：111840, 終了ページ：111840, 2023年11月, ［査読有り］
  Elsevier BV, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.plantsci.2023.111840
  DOI ID：10.1016/j.plantsci.2023.111840, ISSN：0168-9452
• Heterologous expression of mtf and mtc genes of Pseudanabaena foetida var. intermedia is sufficient to produce 2-methylisoborneol in Escherichia coli.　　　　　　　　　　　　　　　
  Kaushalya Dayarathne; Toshiki Ishikawa; Satoru Watanabe; Yuuma Ishikawa; Kadeer Aikeranmu; Hina Kitagawaa; Natsumi Komatsubara; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Microbiology spectrum, 巻：11, 号：5, 開始ページ：e0256123, 2023年09月, ［査読有り］, ［国際誌］
  Microbial volatile metabolite 2-methylisoborneol (2-MIB) causes odor and taste issues in drinking water, making it unappealing for human consumption. It has been suggested that 2-MIB biosynthesis consists of two main steps, namely, methylation of geranyl diphosphate into 2-methyl geranyl diphosphate by geranyl diphosphate methyl transferase (GPPMT) and subsequent cyclization into 2-MIB by 2-MIB synthase (MIBS). Pseudanabaena foetida var. intermedia is a 2-MIB-producing cyanobacterium whose GPPMT and MIBS enzymes are encoded by adjacent mtf and mtc genes. The present study identified a 2-MIB-related gene cluster composed of cnbA, mtf, mtc, and cnbB genes in P. foetida var. intermedia. The two homologous cyclic nucleotide-binding protein genes, cnbA and cnbB, were detected adjacent to the mtf and mtc genes, respectively. The nucleotide sequence of the cnbA-mtf-mtc-cnbB gene cluster showed 99.55% identity with 2-MIB synthesis-associated gene cluster of Pseudanabaena sp. dqh15. RT-PCR results revealed that mtf and mtc genes are co-expressed, while cnbA and cnbB genes are expressed independently in P. foetida var. intermedia. To investigate whether only mtf and mtc genes are sufficient for 2-MIB synthesis, the two-gene unit (mtf-mtc) was introduced into Escherichia coli strain JM109 via overexpression vector pYS1C. Gas chromatograph-mass spectrometry results showed that the E. coli strain transformed with mtf-mtc was able to produce 2-MIB. The intracellular 2-MIB level in P. foetida var. intermedia was higher than the extracellular 2-MIB level, while the transformed E. coli strain showed an opposite trend. Growth inhibition was observed in the 2-MIB-producing transformed E. coli strain. IMPORTANCE Contamination of drinking water with odiferous microbial metabolite 2-MIB is a worldwide concern. Removal of 2-MIB from drinking water burdens the water purification process. Therefore, it is important to search for alternative methods, such as suppressing the production of 2-MIB by aquatic microorganisms. For that, it is necessary to expand the current knowledge about the mechanism of 2-MIB synthesis at the genetic level. This study revealed that mtf and mtc genes of the 2-MIB-related gene cluster are transcribed as a single unit in P. foetida var. intermedia, and the expression of both mtf and mtc genes is essential and sufficient for 2-MIB synthesis in E. coli heterologous gene expression system.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1128/spectrum.02561-23
  DOI ID：10.1128/spectrum.02561-23, PubMed ID：37732762, PubMed Central ID：PMC10580876
• NAC domain transcription factors VNI2 and ATAF2 form protein complexes and regulate leaf senescence.　　　　　　　　　　　　　　　
  Isura Sumeda Priyadarshana Nagahage; Kohei Matsuda; Kyoko Miyashita; Sumire Fujiwara; Chanaka Mannapperuma; Takuya Yamada; Shingo Sakamoto; Toshiki Ishikawa; Minoru Nagano; Misato Ohtani; Ko Kato; Hirofumi Uchimiya; Nobutaka Mitsuda; Maki Kawai-Yamada; Taku Demura; Masatoshi Yamaguchi
  Plant direct, 巻：7, 号：9, 開始ページ：e529, 2023年09月, ［査読有り］, ［国際誌］
  The NAM, ATAF1/2, and CUC2 (NAC) domain transcription factor VND-INTERACTING2 (VNI2) negatively regulates xylem vessel formation by interacting with another NAC domain transcription factor, VASCULAR-RELATED NAC-DOMAIN7 (VND7), a master regulator of xylem vessel formation. Here, we screened interacting proteins with VNI2 using yeast two-hybrid assay and isolated two NAC domain transcription factors, Arabidopsis thaliana ACTIVATION FACTOR 2 (ATAF2) and NAC DOMAIN CONTAINING PROTEIN 102 (ANAC102). A transient gene expression assay showed that ATAF2 upregulates the expression of genes involved in leaf senescence, and VNI2 effectively inhibits the transcriptional activation activity of ATAF2. vni2 mutants accelerate leaf senescence, whereas ataf2 mutants delay leaf senescence. In addition, the accelerated leaf senescence phenotype of the vni2 mutant is recovered by simultaneous mutation of ATAF2. Our findings strongly suggest that VNI2 interacts with and inhibits ATAF2, resulting in negatively regulating leaf senescence.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pld3.529
  DOI ID：10.1002/pld3.529, PubMed ID：37731912, PubMed Central ID：PMC10507225
• Metabolic changes associated with dark-induced leaf senescence in Arabidopsis nadk2 mutants　　　　　　　　　　　　　　　
  Chaomurilege; Atsuko Miyagi; Toshiki Ishikawa; Masatoshi Yamaguchi; Hideki Murayama; Maki Kawai-Yamada
  Plant Signaling and Behavior, 巻：18, 号：1, 開始ページ：e2215618, 2023年05月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15592324.2023.2215618
  DOI ID：10.1080/15592324.2023.2215618
• Chloroplastic Sec14-like proteins modulate growth and phosphate deficiency responses in Arabidopsis and rice
  Mailun Yang; Yasuhito Sakruaba; Toshiki Ishikawa; Namie Ohtsuki; Maki Kawai-Yamada; Shuichi Yanagisawa
  Plant Physiology, 2023年04月, ［査読有り］
  Abstract
  
  Phosphorus is an essential nutrient acquired from soil as phosphate (Pi), and its deficiency severely reduces plant growth and crop yield. Here, we show that single nucleotide polymorphisms (SNPs) at the PHOSPHATIDYLINOSITOL TRANSFER PROTEIN7 (AtPITP7) locus, which encodes a chloroplastic Sec14-like protein, are associated with genetic diversity regarding Pi uptake activity in Arabidopsis (Arabidopsis thaliana). Inactivation of AtPITP7 and its rice (Oryza sativa) homolog (OsPITP6) through T-DNA insertion and CRISPR/Cas9-mediated gene editing, respectively, decreased Pi uptake and plant growth, regardless of Pi availability. By contrast, overexpression of AtPITP7 and OsPITP6 enhanced Pi uptake and plant growth, especially under limited Pi supply. Importantly, overexpression of OsPITP6 increased the tiller number and grain yield in rice. Targeted metabolome analysis of glycerolipids in leaves and chloroplasts revealed that inactivation of OsPITP6 alters phospholipid contents, independent of Pi availability, diminishing the reduction in phospholipid content and increase in glycolipid content induced by Pi deficiency; meanwhile, overexpression of OsPITP6 enhanced Pi deficiency-induced metabolic alterations. Together with transcriptome analysis of ospitp6 rice plants and phenotypic analysis of grafted Arabidopsis chimeras, these results suggest that chloroplastic Sec14-like proteins play an essential role in growth modulations in response to changes in Pi availability, although their function is critical for plant growth under any Pi condition. The superior traits of OsPITP6-overexpressing rice plants also highlight the potential of OsPITP6 and its homologs in other crops as additional tools for improving Pi uptake and plant growth in low Pi environments.
  Oxford University Press (OUP), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/plphys/kiad212
  DOI ID：10.1093/plphys/kiad212, ISSN：0032-0889, eISSN：1532-2548
• Loss of peroxisomal NAD kinase 3 (NADK3) affects photorespiration metabolism in Arabidopsis　　　　　　　　　　　　　　　
  Shota Suzuki; Daimu Tanaka; Atsuko Miyagi; Kentaro Takahara; Masaru Kono; Chaomurilege; Ko Noguchi; Toshiki Ishikawa; Minoru Nagano; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Journal of Plant Physiology, 巻：283, 開始ページ：153950, 2023年03月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2023.153950
  DOI ID：10.1016/j.jplph.2023.153950
• Dynamic seasonal changes in photosynthesis systems in leaves of Asarum tamaense, an evergreen understorey herbaceous species　　　　　　　　　　　　　　　
  Naoki Wada; Issei Kondo; Ryouichi Tanaka; Junko Kishimoto; Atsuko Miyagi; Maki Kawai-Yamada; Yusuke Mizokami; Ko Noguchi
  Annals of Botany, 巻：in press, 2022年12月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/aob/mcac156
  DOI ID：10.1093/aob/mcac156
• Arabidopsis nitrate-induced aspartate oxidase gene expression is necessary to maintain metabolic balance under nitrogen nutrient fluctuation
  Moriaki Saito; Mineko Konishi; Atsuko Miyagi; Yasuhito Sakuraba; Maki Kawai-Yamada; Shuichi Yanagisawa
  Communications Biology, 巻：5, 号：1, 2022年12月, ［査読有り］
  Abstract
  
  Nitrate is a nutrient signal that regulates growth and development through NLP transcription factors in plants. Here we identify the L-aspartate oxidase gene (AO) necessary for de novo NAD⁺ biosynthesis as an NLP target in Arabidopsis. We investigated the physiological significance of nitrate-induced AO expression by expressing AO under the control of the mutant AO promoter lacking the NLP-binding site in the ao mutant. Despite morphological changes and severe reductions in fresh weight, the loss of nitrate-induced AO expression resulted in minimum effects on NAD(H) and NADP(H) contents, suggesting compensation of decreased de novo NAD⁺ biosynthesis by reducing the growth rate. Furthermore, metabolite profiling and transcriptome analysis revealed that the loss of nitrate-induced AO expression causes pronounced impacts on contents of TCA cycle- and urea cycle-related metabolites, gene expression profile, and their modifications in response to changes in the nitrogen nutrient condition. These results suggest that proper maintenance of metabolic balance requires the coordinated regulation of multiple metabolic pathways by NLP-mediated nitrate signaling in plants.
  Springer Science and Business Media LLC, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1038/s42003-022-03399-5
  DOI ID：10.1038/s42003-022-03399-5, eISSN：2399-3642
• Metabolomic analysis of rice brittle culm mutants reveals each mutant- specific metabolic pattern in each organ
  Atsuko Miyagi; Kazuhisa Mori; Toshiki Ishikawa; Satoshi Ohkubo; Shunsuke Adachi; Masatoshi Yamaguchi; Taiichiro Ookawa; Toshihisa Kotake; Maki Kawai-Yamada
  Metabolomics, 巻：18, 号：12, 2022年11月, ［査読有り］
  Springer Science and Business Media LLC, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-022-01958-9
  DOI ID：10.1007/s11306-022-01958-9, eISSN：1573-3890
• Loss of chloroplast-localized NAD kinase causes ROS stress in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Chaomurilege; Yanhui Zu; Atsuko Miyagi; Shin-Nosuke Hashida; Toshiki Ishikawa; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Journal of Plant Research, 巻：in press, 2022年11月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10265-022-01420-w
  DOI ID：10.1007/s10265-022-01420-w
• Sphingolipids with 2-hydroxy fatty acids aid in plasma membrane nanodomain organization and oxidative burst
  Tomomi Ukawa; Fumihiko Banno; Toshiki Ishikawa; Kota Kasahara; Yuuta Nishina; Rika Inoue; Keigo Tsujii; Masatoshi Yamaguchi; Takuya Takahashi; Yoichiro Fukao; Maki Kawai-Yamada; Minoru Nagano
  Plant Physiology, 巻：189, 号：2, 開始ページ：839, 終了ページ：857, 2022年06月, ［査読有り］
  Abstract
  
  Plant sphingolipids mostly possess 2-hydroxy fatty acids (HFA), the synthesis of which is catalyzed by FA 2-hydroxylases (FAHs). In Arabidopsis (Arabidopsis thaliana), two FAHs (FAH1 and FAH2) have been identified. However, the functions of FAHs and sphingolipids with HFAs (2-hydroxy sphingolipids) are still unknown because of the lack of Arabidopsis lines with the complete deletion of FAH1. In this study, we generated a FAH1 mutant (fah1c) using CRISPR/Cas9-based genome editing. Sphingolipid analysis of fah1c, fah2, and fah1cfah2 mutants revealed that FAH1 hydroxylates very long-chain FAs (VLCFAs), whereas the substrates of FAH2 are VLCFAs and palmitic acid. However, 2-hydroxy sphingolipids are not completely lost in the fah1cfah2 double mutant, suggesting the existence of other enzymes catalyzing the hydroxylation of sphingolipid FAs. Plasma membrane (PM) analysis and molecular dynamics simulations revealed that hydroxyl groups of sphingolipid acyl chains play a crucial role in the organization of nanodomains, which are nanoscale liquid-ordered domains mainly formed by sphingolipids and sterols in the PM, through hydrogen bonds. In the PM of the fah1cfah2 mutant, the expression levels of 26.7% of the proteins, including defense-related proteins such as the pattern recognition receptors (PRRs) brassinosteroid insensitive 1-associated receptor kinase 1 and chitin elicitor receptor kinase 1, NADPH oxidase respiratory burst oxidase homolog D (RBOHD), and heterotrimeric G proteins, were lower than that in the wild-type. In addition, reactive oxygen species (ROS) burst was suppressed in the fah1cfah2 mutant after treatment with the pathogen-associated molecular patterns flg22 and chitin. These results indicated that 2-hydroxy sphingolipids are necessary for the organization of PM nanodomains and ROS burst through RBOHD and PRRs during pattern-triggered immunity.
  Oxford University Press (OUP), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/plphys/kiac134
  DOI ID：10.1093/plphys/kiac134, ISSN：0032-0889, eISSN：1532-2548
• VNI2 effectively inhibits transcriptional activities of VND7 through a conserved sequence　　　　　　　　　　　　　　　
  Aili Ailizati; Isura Sumeda Priyadarshana Nagahage; Atsuko Miyagi; Toshiki Ishikawa; Maki Kawai-Yamada; Taku Demura; Masatoshi Yamaguchi
  Plant Biotechnology, 巻：39, 号：2, 開始ページ：147, 終了ページ：153, 2022年06月, ［査読有り］, ［国際共著］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.22.0122a
  DOI ID：10.5511/plantbiotechnology.22.0122a
• Intraspecific interaction of host plants leads to concentrated distribution of a specialist herbivore through metabolic alterations in the leaves.
  Haruna Ohsaki; Atsuko Miyagi; Maki Kawai-Yamada; Akira Yamawo
  Functional Ecology, 巻：36, 号：3, 開始ページ：779, 終了ページ：793, 2022年03月, ［査読有り］
  Wiley, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/1365-2435.13988
  DOI ID：10.1111/1365-2435.13988, ISSN：0269-8463, eISSN：1365-2435
• An Arabidopsis NAC domain transcriptional activator VND7 negatively regulates VNI2 expression　　　　　　　　　　　　　　　
  Aili Ailizati; Isura Sumeda Priyadarshana Nagahage; Atsuko Miyagi; Toshiki Ishikawa; Maki Kawai-Yamada; Taku Demura; Masatoshi Yamaguchi
  Plant Biotechnology, 巻：38, 号：4, 開始ページ：415, 終了ページ：420, 2021年12月, ［査読有り］, ［国際共著］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.21.1013a
  DOI ID：10.5511/plantbiotechnology.21.1013a
• Change in expression levels of NAD kinase-encoding genes in Flaveria species　　　　　　　　　　　　　　　
  Masami Tanaka; Yuuma Ishikawa; Sayaka Suzuki; Takako Ogawa; Yukimi Y. Taniguchi; Atsuko Miyagi; Toshiki Ishikawa; Masatoshi Yamaguchi; Yuri N. Munekage; Maki Kawai-Yamada
  Journal of Plant Physiology, 巻：265, 開始ページ：153495, 終了ページ：153495, 2021年10月
  Elsevier BV, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2021.153495
  DOI ID：10.1016/j.jplph.2021.153495, ISSN：0176-1617
• The NAD Kinase Slr0400 Functions as a Growth Repressor in Synechocystis sp. PCC 6803　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Cedric Cassan; Aikeranmu Kadeer; Koki Yuasa; Nozomu Sato; Kintake  Sonoike; Yasuko Kaneko; Atsuko Miyagi; Hiroko Takahashi; Toshiki Ishikawa; Masatoshi Yamaguchi; Yoshitaka Nishiyama; Yukako Hihara; Yves Gibon; Maki Kawai-Yamada
  Plant and Cell Physiology, 巻：62, 号：4, 開始ページ：668, 終了ページ：677, 2021年09月, ［査読有り］
  
  NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear. In this study, we report that slr0400, an NADK-encoding gene in Synechocystis, functions as a growth repressor under light-activated heterotrophic growth conditions and light and dark cycle conditions in the presence of glucose. We show, via characterization of NAD(P)(H) content and enzyme activity, that NAD+ accumulation in slr0400-deficient mutant results in the unsuppressed activity of glycolysis and tricarboxylic acid (TCA) cycle enzymes. In determining whether Slr0400 functions as a typical NADK, we found that constitutive expression of slr0400 in an Arabidopsis nadk2-mutant background complements the pale-green phenotype. Moreover, to determine the physiological background behind the growth advantage of mutants lacking slr04000, we investigated the photobleaching phenotype of slr0400-deficient mutant under high-light conditions. Photosynthetic analysis found in the slr0400-deficient mutant resulted from malfunctions in the Photosystem II (PSII) photosynthetic machinery. Overall, our results suggest that NADP(H)/NAD(H) maintenance by slr0400 plays a significant role in modulating glycolysis and the TCA cycle to repress the growth rate and maintain the photosynthetic capacity.
  Oxford University Press (OUP), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcab023
  DOI ID：10.1093/pcp/pcab023, ISSN：0032-0781, eISSN：1471-9053, PubMed ID：33210985, PubMed Central ID：PMC7781788
• Reprogramming sphingolipid glycosylation is required for endosymbiont persistence in Medicago truncatula　　　　　　　　　　　　　　　
  William M. Moore; Candace Chan; Toshiki Ishikawa; Emilie A. Rennie; Heidi M.-L. Wipf; Veronica Benites; Maki Kawai-Yamada; Jenny C. Mortimer; Henrik V. Scheller
  Current Biology, 巻：31, 号：11, 開始ページ：2374, 終了ページ：2385.e4, 2021年06月
  Plant endosymbiosis relies on the development of specialized membranes that encapsulate the endosymbiont and facilitate nutrient exchange. However, the identity and function of lipids within these membrane interfaces is largely unknown. Here, we identify GLUCOSAMINE INOSITOL PHOSPHORYLCERAMIDE TRANSFERASE1 (GINT1) as a sphingolipid glycosyltransferase highly expressed in Medicago truncatula root nodules and roots colonized by arbuscular mycorrhizal (AM) fungi and further demonstrate that this enzyme functions in the synthesis of N-acetyl-glucosamine-decorated glycosyl inositol phosphoryl ceramides (GIPCs) in planta. MtGINT1 expression was developmentally regulated in symbiotic tissues associated with the development of symbiosome and periarbuscular membranes. RNAi silencing of MtGINT1 did not affect overall root growth but strongly impaired nodulation and AM symbiosis, resulting in the senescence of symbiosomes and arbuscules. Our results indicate that, although M. truncatula root sphingolipidome predominantly consists of hexose-decorated GIPCs, local reprogramming of GIPC glycosylation by MtGINT1 is required for the persistence of endosymbionts within the plant cell.
  Cell Press, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.cub.2021.03.067
  DOI ID：10.1016/j.cub.2021.03.067, ISSN：1879-0445, PubMed ID：33857428, SCOPUS ID：85104939324
• The Arabidopsis thaliana nucleotide sugar transporter GONST2 is a functional homolog of GONST1.　　　　　　　　　　　　　　　
  Beibei Jing; Toshiki Ishikawa; Nicole Soltis; Noriko Inada; Yan Liang; Gosia Murawska; Lin Fang; Fekadu Andeberhan; Ramana Pidatala; Xiaolan Yu; Edward Baidoo; Maki Kawai-Yamada; Dominique Loque; Daniel J Kliebenstein; Paul Dupree; Jenny C Mortimer
  Plant direct, 巻：5, 号：3, 開始ページ：e00309, 2021年03月, ［国際誌］
  Glycosylinositolphosphorylceramides (GIPCs) are the predominant lipid in the outer leaflet of the plasma membrane. Characterized GIPC glycosylation mutants have severe or lethal plant phenotypes. However, the function of the glycosylation is unclear. Previously, we characterized Arabidopsis thaliana GONST1 and showed that it was a nucleotide sugar transporter which provides GDP-mannose for GIPC glycosylation. gonst1 has a severe growth phenotype, as well as a constitutive defense response. Here, we characterize a mutant in GONST1's closest homolog, GONST2. The gonst2-1 allele has a minor change to GIPC headgroup glycosylation. Like other reported GIPC glycosylation mutants, gonst1-1gonst2-1 has reduced cellulose, a cell wall polymer that is synthesized at the plasma membrane. The gonst2-1 allele has increased resistance to a biotrophic pathogen Golovinomyces orontii but not the necrotrophic pathogen Botrytis cinerea. Expression of GONST2 under the GONST1 promoter can rescue the gonst1 phenotype, indicating that GONST2 has a similar function to GONST1 in providing GDP-D-Man for GIPC mannosylation.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pld3.309
  DOI ID：10.1002/pld3.309, PubMed ID：33763627, PubMed Central ID：PMC7980081
• The NAD kinase Slr0400 functions as a growth repressor in Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Cedric Cassan; Aikeranmu Kadeer; Koki Yuasa; Nozomu Sato; Kintake Sonoike; Yasuko Kaneko; Atsuko Miyagi; Hiroko Takahashi; Toshiki Ishikawa; Masatoshi Yamaguchi; Yoshitaka Nishiyama; Yukako Hihara; Yves Gibon; Maki Kawai-Yamada
  Plant & cell physiology, 2021年02月, ［国内誌］
  NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear. In this study, we report that slr0400, an NADK-encoding gene in Synechocystis, functions as a growth repressor under light-activated heterotrophic growth conditions and light and dark cycle conditions in the presence of glucose. We show, via characterization of NAD(P)(H) content and enzyme activity, that NAD+ accumulation in slr0400-deficient mutant results in unsuppressed activity of glycolysis and tricarboxylic acid (TCA) cycle enzymes. In determining whether Slr0400 functions as a typical NADK, we found that constitutive expression of slr0400 in an Arabidopsis nadk2-mutant background complements the pale-green phenotype. Moreover, to determine the physiological background behind the growth advantage of mutants lacking slr04000, we investigated the photobleaching phenotype of slr0400-deficient mutant under high-light conditions. Photosynthetic analysis found in the slr0400-deficient mutant resulted from malfunctions in the PSII photosynthetic machinery. Overall, our results suggest that NADP(H)/NAD(H) maintenance by slr0400 plays a significant role in modulating glycolysis and the TCA cycle to repress the growth rate and maintain photosynthetic capacity.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcab023
  DOI ID：10.1093/pcp/pcab023, PubMed ID：33560438
• Redox regulation of NADP-malate dehydrogenase is vital for land plants under fluctuating light environment.　　　　　　　　　　　　　　　
  Yuichi Yokochi; Keisuke Yoshida; Florian Hahn; Atsuko Miyagi; Ken-Ichi Wakabayashi; Maki Kawai-Yamada; Andreas P M Weber; Toru Hisabori
  Proceedings of the National Academy of Sciences of the United States of America, 巻：118, 号：6, 2021年02月, ［国際誌］
  Many enzymes involved in photosynthesis possess highly conserved cysteine residues that serve as redox switches in chloroplasts. These redox switches function to activate or deactivate enzymes during light-dark transitions and have the function of fine-tuning their activities according to the intensity of light. Accordingly, many studies on chloroplast redox regulation have been conducted under the hypothesis that "fine regulation of the activities of these enzymes is crucial for efficient photosynthesis." However, the impact of the regulatory system on plant metabolism is still unclear. To test this hypothesis, we here studied the impact of the ablation of a redox switch in chloroplast NADP-malate dehydrogenase (MDH). By genome editing, we generated a mutant plant whose MDH lacks one of its redox switches and is active even in dark conditions. Although NADPH consumption by MDH in the dark is expected to be harmful to plant growth, the mutant line did not show any phenotypic differences under standard long-day conditions. In contrast, the mutant line showed severe growth retardation under short-day or fluctuating light conditions. These results indicate that thiol-switch redox regulation of MDH activity is crucial for maintaining NADPH homeostasis in chloroplasts under these conditions.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1073/pnas.2016903118
  DOI ID：10.1073/pnas.2016903118, PubMed ID：33531363
• Ceramides mediate positional signals in Arabidopsis thaliana protoderm differentiation
  Kenji Nagata; Toshiki Ishikawa; Maki Kawai-Yamada; Taku Takahashi; Mitsutomo Abe
  Development, 巻：148, 号：2, 開始ページ：dev194969, 終了ページ：dev194969, 2021年01月
  The differentiation of distinct cell types in appropriate patterns is a fundamental process in the development of multicellular organisms. In Arabidopsis thaliana, protoderm/epidermis differentiates as a single cell layer at the outermost position. However, little is known about the molecular nature of the positional signals that achieve correct epidermal cell differentiation. Here, we propose that very-long-chain fatty acid-containing ceramides (VLCFA-Cers) mediate positional signals by stimulating the function of ARABIDOPSIS THALIANA MERISTEM LAYER1 (ATML1), a master regulator of protoderm/epidermis differentiation, during lateral root development. We show that VLCFA-Cers, which are synthesized predominantly in the outermost cells, bind to the lipid-binding domain of ATML1. Importantly, this cell type-specific protein-lipid association alters the activity of ATML1 protein and consequently restricts its expression to the protoderm/epidermis through a transcriptional feedback loop. Furthermore, establishment of a compartment, enriched with VLCFA-containing sphingolipids, at the outer lateral membrane facing the external environment may function as a determinant of protodermal cell fate. Taken together, our results indicate that VLCFA-Cers play a pivotal role in directing protoderm/epidermis differentiation by mediating positional signals to ATML1.
  
  This article has an associated ‘The people behind the papers’ interview.
  The Company of Biologists, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1242/dev.194969
  DOI ID：10.1242/dev.194969, ISSN：0950-1991, eISSN：1477-9129
• Altered metabolism of chloroplastic NAD kinase-overexpressing Arabidopsis in response to magnesium sulfate supplementation.　　　　　　　　　　　　　　　
  Maki Kawai-Yamada; Atsuko Miyagi; Yuki Sato; Yuki Hosoi; Shin-Nosuke Hashida; Toshiki Ishikawa; Masatoshi Yamaguchi
  Plant signaling & behavior, 巻：16, 号：1, 開始ページ：1844509, 終了ページ：1844509, 2020年11月, ［国際誌］
  Nicotinamide adenine dinucleotide (NAD)/NAD phosphate (NADPH) is essential for numerous redox reactions and serve as co-factors in multiple metabolic processes in all organisms. NAD kinase (NADK) is an enzyme involved in the synthesis of NADP+ from NAD+ and ATP. Arabidopsis NADK2 (AtNADK2) is a chloroplast-localizing enzyme that provides recipients of reducing power in photosynthetic electron transfer. When Arabidopsis plants were grown on MS medium supplemented with 5 mM MgSO4, an AtNADK2-overexpressing line exhibited higher glutathione and total sulfur accumulation than control plants. Metabolomic analysis of major amino acids and organic acids using capillary electrophoresis-mass spectrometry demonstrated that overexpression of AtNADK2 affected a range of metabolic processes in response to MgSO4 supplementation.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15592324.2020.1844509
  DOI ID：10.1080/15592324.2020.1844509, PubMed ID：33210985, PubMed Central ID：PMC7781788
• An Arabidopsis NAC domain transcription factor, ATAF2, promotes age-dependent and dark-induced leaf senescence.　　　　　　　　　　　　　　　
  Isura Sumeda Priyadarshana Nagahage; Shingo Sakamoto; Minoru Nagano; Toshiki Ishikawa; Nobutaka Mitsuda; Maki Kawai-Yamada; Masatoshi Yamaguchi
  Physiologia plantarum, 巻：170, 号：2, 開始ページ：299, 終了ページ：308, 2020年10月, ［国際誌］
  Leaf senescence is controlled developmentally and environmentally and is affected by numerous genes, including transcription factors. An Arabidopsis NAC domain transcription factor, ATAF2, is known to regulate biotic stress responses. Recently, we have demonstrated that ATAF2 upregulates ORE1, a key regulator of leaf senescence. Here, to investigate the function of ATAF2 in leaf senescence further, we generated and analyzed overexpressing transgenic and T-DNA inserted mutant lines. Transient expression analysis indicated that ATAF2 upregulates several NAC domain transcription factors that regulate senescence. Indeed, ATAF2 overexpression induced the expression of senescence-related genes, thereby accelerating leaf senescence, whereas the expression of such genes in ataf2 mutants was lower than that of wild-type plants. Furthermore, the ataf2 mutants exhibited significant delays in dark-induced leaf senescence. It was also found that ATAF2 induces the expression of transcription factors, which both promotes and represses leaf senescence. The present study demonstrates that ATAF2 promotes leaf senescence in response to developmental and environmental signals.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/ppl.13156
  DOI ID：10.1111/ppl.13156, PubMed ID：32579231
• Metabolome analysis of rice leaves to obtain low-oxalate strain from ion beam-mutagenised population.　　　　　　　　　　　　　　　
  Atsuko Miyagi; Takuya Saimaru; Nozomi Harigai; Yutaka Oono; Yoshihiro Hase; Maki Kawai-Yamada
  Metabolomics : Official journal of the Metabolomic Society, 巻：16, 号：9, 開始ページ：94, 終了ページ：94, 2020年09月, ［国際誌］
  INTRODUCTION: Rice leaves and stems, which can be used as rice straw for livestock feed, accumulate soluble oxalate. The oxalate content often reaches 5% of the dry weight leaves. Excess uptake of oxalate-rich plants causes mineral deficiencies in vertebrates, so it is important to reduce the oxalate content in rice leaves to produce high-quality rice straw. However, the mechanism of oxalate accumulation in rice has remained unknown. OBJECTIVES: To understand metabolic networks relating oxalate accumulation in rice. METHODS: In this study, we performed metabolome analysis of rice M2 population generated by ion-beam irradiation using CE-MS. RESULTS: The result showed wide variation of oxalate contents in M2 plants compared with those of control plants. Multivariate analyses of metabolome dataset revealed that oxalate accumulation was strongly related with anionic compounds such as 2OG and succinate. For low-oxalate plants, four patterns of metabolic alterations affected oxalate contents in the M2 leaves were observed. In M3 plants, we found putative low-oxalate line obtained from low-oxalate M2 mutant. CONCLUSIONS: These findings would lead to produce the low-oxalate rice and to understand the oxalate synthesis in plants.These findings would lead to produce the low-oxalate rice and to understand the oxalate synthesis in plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-020-01713-y
  DOI ID：10.1007/s11306-020-01713-y, PubMed ID：32894362
• Quantitative and Qualitative Analyses of Triacylglycerol Production in the Wild-Type Cyanobacterium Synechocystis sp. PCC 6803 and the Strain Expressing AtfA from Acinetobacter baylyi ADP1.　　　　　　　　　　　　　　　
  Motoki Tanaka; Toshiki Ishikawa; So Tamura; Yujiro Saito; Maki Kawai-Yamada; Yukako Hihara
  Plant & cell physiology, 巻：61, 号：9, 開始ページ：1537, 終了ページ：1547, 2020年09月, ［国内誌］
  Although cyanobacteria do not possess wax ester synthase/acyl-CoA:diacylglycerol acyltransferase (WS/DGAT), the bacterial enzyme for triacylglycerol (TAG) production, there have been several studies reporting the accumulation of TAG-like compounds in cyanobacteria. In this study, we aimed to evaluate TAG productivity of the ΔrecJ::atfA strain of Synechocystis sp. PCC 6803 generated by inserting atfA encoding WS/DGAT from Acinetobacter baylyi ADP1 into recJ (sll1354), together with the wild type (WT) and the gene-disrupted strain of slr2103 having homology with eukaryotic DGAT2 gene family (Δ2103). Thin-layer chromatography (TLC) of neutral lipids or isolation of the neutral lipid-enriched fraction followed by gas chromatography or liquid chromatography-tandem mass spectrometry was employed for analyses. The ΔrecJ::atfA strain accumulated 0.508 nmol ml-1OD730-1 of TAG after a week of incubation at 100 μmol photons m-2 s-1. The saturated fatty acids C16:0 and C18:0 accounted for about 50% and 20% of the TAG fatty acids, respectively, suggesting that de novo-synthesized fatty acids were preferentially incorporated into TAG molecules. When the neutral lipid profile of the lipid extracts was examined by TLC, a spot located in a slightly lower position compared with the TAG standard was detected in WT but not in the Δ2103 strain. TAG accumulation levels of both strains was only 0.01-0.03 nmol ml-1OD730-1, but the fatty acid composition was substantially different from that of the background. These results suggest that trace amounts of TAG can be produced in Synechocystis cells by enzymes other than Slr2103, and major constituents of the TAG-like spot are unknown lipid species produced by Slr2103.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcaa069
  DOI ID：10.1093/pcp/pcaa069, PubMed ID：32433767
• Generation of Arabidopsis lines with a red fluorescent marker for endoplasmic reticulum using a tail-anchored protein cytochrome b5 -B.　　　　　　　　　　　　　　　
  Minoru Nagano; Haruko Ueda; Yoichiro Fukao; Maki Kawai-Yamada; Ikuko Hara-Nishimura
  Plant signaling & behavior, 巻：15, 号：9, 開始ページ：1790196, 終了ページ：1790196, 2020年09月, ［国際誌］
  The endoplasmic reticulum (ER) is a multifunctional organelle that performs multiple cellular activities in eukaryotes. Visualizing ER using fluorescent proteins is a powerful method of analyzing its dynamics and to understand its functions. However, red fluorescent proteins with both an N-terminal signal peptide (SP) and a C-terminal ER retention tetrapeptide (HDEL) often cause mislocalization to vacuoles or extracellular spaces when they are constitutively expressed in Arabidopsis. To obtain a red fluorescent ER marker, we selected Arabidopsis cytochrome b5 -B (Cb5-B), a tail-anchored (TA) protein on the ER membrane. Its localization is determined by the transmembrane domain (TMD) and tail domain at the C-terminus. We fused the TMD and the tail domain of Cb5-B to the C-terminus of a red fluorescent protein, tdTomato (tdTomato-CTT). When tdTomato-CTT was constitutively expressed under the ubiquitin10 promoter in Arabidopsis, the fluorescent signal was exclusively detected at the ER by means of the reliable ER marker SP-GFP-HDEL. Therefore, tdTomato-CTT can accurately visualize the ER in stable Arabidopsis lines. Additionally, transient assays showed that tdTomato-CTT can also be used as an ER marker in onion, rice, and Nicotiana benthamiana. We believe that TA proteins could be used to generate various organellar membrane markers in plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15592324.2020.1790196
  DOI ID：10.1080/15592324.2020.1790196, PubMed ID：32633191
• Phosphorus toxicity disrupts Rubisco activation and reactive oxygen species defence systems by phytic acid accumulation in leaves.　　　　　　　　　　　　　　　
  Daisuke Takagi; Atsuko Miyagi; Youshi Tazoe; Mao Suganami; Maki Kawai-Yamada; Akihiro Ueda; Yuji Suzuki; Ko Noguchi; Naoki Hirotsu; Amane Makino
  Plant, cell & environment, 巻：43, 号：9, 開始ページ：2033, 終了ページ：2053, 2020年09月, ［査読有り］, ［国際誌］
  Phosphorus (P) is an essential mineral nutrient for plants. Nevertheless, excessive P accumulation in leaf mesophyll cells causes necrotic symptoms in land plants; this phenomenon is termed P toxicity. However, the detailed mechanisms underlying P toxicity in plants have not yet been elucidated. This study aimed to investigate the molecular mechanism of P toxicity in rice. We found that under excessive inorganic P (Pi) application, Rubisco activation decreased and photosynthesis was inhibited, leading to lipid peroxidation. Although the defence systems against reactive oxygen species accumulation were activated under excessive Pi application conditions, the Cu/Zn-type superoxide dismutase activities were inhibited. A metabolic analysis revealed that excessive Pi application led to an increase in the cytosolic sugar phosphate concentration and the activation of phytic acid synthesis. These conditions induced mRNA expression of genes that are activated under metal-deficient conditions, although metals did accumulate. These results suggest that P toxicity is triggered by the attenuation of both photosynthesis and metal availability within cells mediated by phytic acid accumulation. Here, we discuss the whole phenomenon of P toxicity, beginning from the accumulation of Pi within cells to death in land plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/pce.13772
  DOI ID：10.1111/pce.13772, ORCID：71982429, PubMed ID：32281116
• Dehydroascorbate Reductases and Glutathione Set a Threshold for High-Light-Induced Ascorbate Accumulation.　　　　　　　　　　　　　　　
  Yusuke Terai; Hiromi Ueno; Takahisa Ogawa; Yoshihiro Sawa; Atsuko Miyagi; Maki Kawai-Yamada; Takahiro Ishikawa; Takanori Maruta
  Plant physiology, 巻：183, 号：1, 開始ページ：112, 終了ページ：122, 2020年05月, ［査読有り］, ［国際誌］
  Plants require a high concentration of ascorbate as a redox buffer for survival under stress conditions, such as high light. Dehydroascorbate reductases (DHARs) are enzymes that catalyze the reduction of DHA to ascorbate using reduced glutathione (GSH) as an electron donor, allowing rapid ascorbate recycling. However, a recent study using an Arabidopsis (Arabidopsis thaliana) triple mutant lacking all three DHAR genes (herein called ∆dhar) did not find evidence for their role in ascorbate recycling under oxidative stress. To further study the function of DHARs, we generated ∆dhar Arabidopsis plants as well as a quadruple mutant line combining ∆dhar with an additional vtc2 mutation that causes ascorbate deficiency. Measurements of ascorbate in these mutants under low- or high-light conditions indicated that DHARs have a nonnegligible impact on full ascorbate accumulation under high light, but that they are dispensable when ascorbate concentrations are low to moderate. Because GSH itself can reduce DHA nonenzymatically, we used the pad2 mutant that contains ∼30% of the wild-type GSH level. The pad2 mutant accumulated ascorbate at a wild-type level under high light; however, when the pad2 mutation was combined with ∆dhar, there was near-complete inhibition of high-light-dependent ascorbate accumulation. The lack of ascorbate accumulation was consistent with a marked increase in the ascorbate degradation product threonate. These findings indicate that ascorbate recycling capacity is limited in ∆dhar pad2 plants, and that both DHAR activity and GSH content set a threshold for high-light-induced ascorbate accumulation.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.19.01556
  DOI ID：10.1104/pp.19.01556, PubMed ID：32205453, PubMed Central ID：PMC7210653
• Measurement of Chloroplastic NAD Kinase Activity and Whole Tissue NAD Kinase Assay　　　　　　　　　　　　　　　
  Yuma Ishikawa; Maki Kawai-Yamada; Shin-nosuke Hashida
  BIO-PROTOCOL, 巻：10, 号：1, 2020年
  Bio-Protocol, {LLC}, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21769/bioprotoc.3480
  DOI ID：10.21769/bioprotoc.3480, ISSN：2331-8325, ORCID：83058164
• Plant-Unique cis/trans Isomerism of Long-Chain Base Unsaturation is Selectively Required for Aluminum Tolerance Resulting from Glucosylceramide-Dependent Plasma Membrane Fluidity.　　　　　　　　　　　　　　　
  Masaya Sato; Minoru Nagano; Song Jin; Atsuko Miyagi; Masatoshi Yamaguchi; Maki Kawai-Yamada; Toshiki Ishikawa
  Plants (Basel, Switzerland), 巻：9, 号：1, 開始ページ：19, 2019年12月, ［査読有り］, ［国際誌］
  Cis/trans isomerism of the Δ8 unsaturation of long-chain base (LCB) is found only in plant sphingolipids. This unique geometry is generated by sphingolipid LCB Δ8 desaturase SLD which produces both isomers at various ratios, resulting in diverse cis/trans ratios in plants. However, the biological significance of this isomeric diversity remains controversial. Here, we show that the plant-specific cis unsaturation of LCB selectively contributes to glucosylceramide (GlcCer)-dependent tolerance to aluminum toxicity. We established three transgenic rice lines with altered LCB unsaturation profiles. Overexpression of SLD from rice (OsSLD-OX), which preferentially exhibits cis-activity, or Arabidopsis (AtSLD-OX), showing preference for trans-activity, facilitated Δ8 unsaturation in different manners: a slight increase of cis-unsaturated glycosylinositolphosphoceramide (GIPC) in OsSLD-OX, and a drastic increase of trans-unsaturated GlcCer and GIPC in AtSLD-OX. Disruption of LCB Δ4 desaturase (des) significantly decreased the content of GlcCer. Fluorescence imaging analysis revealed that OsSLD-OX and AtSLD-OX showed increased plasma membrane fluidity, whereas des had less fluidity, demonstrating that the isomers universally contributed to increasing membrane fluidity. However, the results of a hydroponic assay showed decreased aluminum tolerance in AtSLD-OX and des compared to OsSLD-OX and the control plants, which did not correlate with membrane fluidity. These results suggest that cis-unsaturated GlcCer, not GIPC, selectively serves to maintain the membrane fluidity specifically associated with aluminum tolerance.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/plants9010019
  DOI ID：10.3390/plants9010019, PubMed ID：31877922, PubMed Central ID：PMC7020186
• Glycosylinositol phosphoceramide-specific phospholipase D activity catalyzes transphosphatidylation.　　　　　　　　　　　　　　　
  Rumana Yesmin Hasi; Makoto Miyagi; Katsuya Morito; Toshiki Ishikawa; Maki Kawai-Yamada; Hiroyuki Imai; Tatsuya Fukuta; Kentaro Kogure; Kaori Kanemaru; Junji Hayashi; Ryushi Kawakami; Tamotsu Tanaka
  Journal of biochemistry, 巻：166, 号：5, 開始ページ：441, 終了ページ：448, 2019年11月, ［査読有り］, ［国際誌］
  Glycosylinositol phosphoceramide (GIPC) is the most abundant sphingolipid in plants and fungi. Recently, we detected GIPC-specific phospholipase D (GIPC-PLD) activity in plants. Here, we found that GIPC-PLD activity in young cabbage leaves catalyzes transphosphatidylation. The available alcohol for this reaction is a primary alcohol with a chain length below C4. Neither secondary alcohol, tertiary alcohol, choline, serine nor glycerol serves as an acceptor for transphosphatidylation of GIPC-PLD. We also found that cabbage GIPC-PLD prefers GIPC containing two sugars. Neither inositol phosphoceramide, mannosylinositol phosphoceramide nor GIPC with three sugar chains served as substrate. GIPC-PLD will become a useful catalyst for modification of polar head group of sphingophospholipid.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/jb/mvz056
  DOI ID：10.1093/jb/mvz056, ISSN：0021-924X, PubMed ID：31504617
• High-yielding rice Takanari has superior photosynthetic response to a commercial rice Koshihikari under fluctuating light.　　　　　　　　　　　　　　　
  Shunsuke Adachi; Yu Tanaka; Atsuko Miyagi; Makoto Kashima; Ayumi Tezuka; Yoshihiro Toya; Shunzo Kobayashi; Satoshi Ohkubo; Hiroshi Shimizu; Maki Kawai-Yamada; Rowan F Sage; Atsushi J Nagano; Wataru Yamori
  Journal of experimental botany, 巻：70, 号：19, 開始ページ：5287, 終了ページ：5297, 2019年10月, ［査読有り］, ［国際誌］
  Leaves within crop canopies experience variable light over the course of a day, which greatly affects photosynthesis and crop productivity. Little is known about the mechanisms of the photosynthetic response to fluctuating light and their genetic control. Here, we examined gas exchange, metabolite levels, and chlorophyll fluorescence during the photosynthetic induction response in an Oryza sativa indica cultivar with high yield (Takanari) and a japonica cultivar with lower yield (Koshihikari). Takanari had a faster induction response to sudden increases in light intensity than Koshihikari, as demonstrated by faster increases in net CO2 assimilation rate, stomatal conductance, and electron transport rate. In a simulated light regime that mimicked a typical summer day, the faster induction response in Takanari increased daily CO2 assimilation by 10%. The faster response of Takanari was explained in part by its maintenance of a larger pool of Calvin-Benson cycle metabolites. Together, the rapid responses of electron transport rate, metabolic flux, and stomatal conductance in Takanari contributed to the greater daily carbon gain under fluctuating light typical of natural environments.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/jxb/erz304
  DOI ID：10.1093/jxb/erz304, ISSN：0022-0957, PubMed ID：31257443, PubMed Central ID：PMC6793460
• Excessive assimilation of ammonium by plastidic glutamine synthetase is a major cause of ammonium toxicity in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Hachiya T; Inaba J; Wakazaki M; Sato M; Toyooka K; Miyagi A; Kawai-Yamada M; Kiba T; Gojon A; Sakakibara H
  bioRxiv, 巻：https://doi.org/10.1101/764324, 2019年09月
  英語, 研究論文（学術雑誌）
• Oxalate contents in leaves of two rice cultivars grown at a free-air CO₂ enrichment (FACE) site　　　　　　　　　　　　　　　
  Atsuko Miyagi; Ko Noguchi; Takeshi Tokida; Yasuhiro Usui; Hirofumi Nakamura; Hidemitsu Sakai; Toshihiro Hasegawa; Maki Kawai-Yamada
  Plant Production Science, 巻：22, 号：3, 開始ページ：407, 終了ページ：411, 2019年07月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/1343943X.2019.1598272
  DOI ID：10.1080/1343943X.2019.1598272
• Mitochondrial AOX Supports Redox Balance of Photosynthetic Electron Transport, Primary Metabolite Balance, and Growth in Arabidopsis thaliana under High Light.　　　　　　　　　　　　　　　
  Jiang Z; Watanabe CKA; Miyagi A; Kawai-Yamada M; Terashima I; Noguchi K
  International journal of molecular sciences, 巻：20, 号：12, 2019年06月, ［査読有り］
  DOI：https://doi.org/10.3390/ijms20123067
  DOI ID：10.3390/ijms20123067, PubMed ID：31234590
• One of the NAD kinases, sll1415, is required for the glucose metabolism of Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Ishikawa Y; Miyagi A; Ishikawa T; Nagano M; Yamaguchi M; Hihara Y; Kaneko Y; Kawai-Yamada M
  The Plant journal : for cell and molecular biology, 巻：98, 号：4, 開始ページ：654, 終了ページ：666, 2019年05月, ［査読有り］, ［国際誌］
  Pyridine nucleotides (NAD(P)(H)) are electron carriers that are the driving forces in various metabolic pathways. Phosphorylation of NAD(H) to NADP(H) is performed by the enzyme NAD kinase (NADK). Synechocystis sp. PCC 6803 harbors two genes (sll1415 and slr0400) that encode proteins with NADK homology. When genetic mutants for sll1415 and slr0400 (Δ1415 and Δ0400, respectively) were cultured under photoheterotrophic growth conditions only the Δ1415 cells showed a growth defect. In wild-type cells, the sll1415 transcript accumulated after the cells were transferred to photoheterotrophic conditions. Furthermore, NAD(P)(H) measurements demonstrated that a dynamic metabolic conversion was implemented during the adaptation from photoautotrophic to photoheterotrophic conditions. Electron microscopy observation and biochemistry quantification demonstrated the accumulation of glycogen in the Δ1415 cells under photoheterotrophic conditions at 96 h. Quantitative real-time reverse transcription PCR (qRT-PCR) demonstrated the accumulation of mRNAs that encoded glycogen biosynthesis-related enzymes in photoheterotrophic Δ1415 cells. At 96 h, enzyme activity measurement in the photoheterotrophic Δ1415 cells demonstrated that the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were decreased, but the activities of glucose dehydrogenase were increased. Furthermore, metabolomics analysis demonstrated that the Δ1415 cells showed increased glucose-6-phosphate and 6-phosphogluconate content at 96 h. Therefore, sll1415 has a significant function in the oxidative pentose phosphate (OPP) pathway for catabolism of glucose under photoheterotrophic conditions. Additionally, it is presumed that the slr0400 had a different role in glucose catabolism during growth. These results suggest that the two Synechocystis sp. PCC 6803 NADKs (Sll1415 and Slr0400) have distinct functions in photoheterotrophic cyanobacterial metabolism.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.14262
  DOI ID：10.1111/tpj.14262, ISSN：0960-7412, PubMed ID：30693583
• Detection of Disulfides in Protein Extracts of Arabidopsis thaliana Using Monobromobimane (mBB)　　　　　　　　　　　　　　　
  Shin-nosuke Hashida; Maki Kawai-Yamada
  BIO-PROTOCOL, 巻：9, 号：5, 2019年
  Bio-Protocol, {LLC}, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21769/bioprotoc.3183
  DOI ID：10.21769/bioprotoc.3183, ISSN：2331-8325, ORCID：83058156
• Metabolic and biochemical responses of Potamogeton anguillanus Koidz. (Potamogetonaceae) to low oxygen conditions.　　　　　　　　　　　　　　　
  Parveen M; Miyagi A; Kawai-Yamada M; Rashid MH; Asaeda T
  Journal of plant physiology, 巻：232, 開始ページ：171, 終了ページ：179, 2019年01月, ［査読有り］
  DOI：https://doi.org/10.1016/j.jplph.2018.11.023
  DOI ID：10.1016/j.jplph.2018.11.023, ISSN：0176-1617, PubMed ID：30537604
• Arabidopsis Bax inhibitor-1 interacts with enzymes related to very-long-chain fatty acid synthesis.　　　　　　　　　　　　　　　
  Nagano M; Kakuta C; Fukao Y; Fujiwara M; Uchimiya H; Kawai-Yamada M
  Journal of plant research, 巻：132, 号：1, 開始ページ：131, 終了ページ：143, 2019年01月, ［査読有り］
  Springer Science and Business Media LLC, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10265-018-01081-8
  DOI ID：10.1007/s10265-018-01081-8, ISSN：0918-9440, eISSN：1618-0860, PubMed ID：30604175
• Physiological Significance of NAD Kinases in Cyanobacteria.　　　　　　　　　　　　　　　
  Ishikawa Y; Kawai-Yamada M
  Frontiers in plant science, 巻：10, 開始ページ：847, 2019年, ［査読有り］
  DOI：https://doi.org/10.3389/fpls.2019.00847
  DOI ID：10.3389/fpls.2019.00847, PubMed ID：31316540
• Inter-Organelle NAD Metabolism Underpinning Light Responsive NADP Dynamics in Plants.　　　　　　　　　　　　　　　
  Hashida SN; Kawai-Yamada M
  Frontiers in plant science, 巻：10, 開始ページ：960, 2019年, ［査読有り］
  DOI：https://doi.org/10.3389/fpls.2019.00960
  DOI ID：10.3389/fpls.2019.00960, PubMed ID：31404160
• Effects of inactivation of the cyAbrB2 transcription factor together with glycogen synthesis on cellular metabolism and free fatty acid production in the cyanobacterium Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Yuta Kodama; Akihito Kawahara; Atsuko Miyagi; Toshiki Ishikawa; Maki Kawai-Yamada; Yasuko Kaneko; Yasushi Takimura; Yukako Hihara
  Biotechnology and Bioengineering, 巻：115, 号：12, 開始ページ：2974, 終了ページ：2985, 2018年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/bit.26842
  DOI ID：10.1002/bit.26842, ISSN：1097-0290
• A homologue of dihydrosphingosine C4 hydroxylase gene family member, DSH5, that shows spatial expression in rice; its ectopic expression leads to a lethal phenotype.　　　　　　　　　　　　　　　
  Tomohiro Imamura; Chihiro Obata; Kazuyoshi Yoneyama; Masatoshi Ichikawa; Akane Ikura; Hiromi Mutsuro-Aoki; Toshiki Ishikawa; Maki Kawai-Yamada; Tadamasa Sasaki; Hiroaki Kusano; Hiroaki Shimada
  GENES & GENETIC SYSTEMS, 巻：93, 開始ページ：135, 終了ページ：142, 2018年10月, ［査読有り］
  英語
  DOI：https://doi.org/10.1266/ggs/17-00054
  DOI ID：10.1266/ggs/17-00054
• An NAC domain transcription factor ATAF2 acts as transcriptional activator or repressor dependent on promoter context　　　　　　　　　　　　　　　
  Isura Sumeda Priyadarshana Nagahage; Shingo Sakamoto; Minoru Nagano; Toshiki Ishikawa; Maki Kawai-Yamada; Nobutaka Mitsuda; Masatoshi Yamaguchi
  Plant Biotechnology, 巻：35, 号：3, 開始ページ：285, 終了ページ：289, 2018年09月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.18.0507a
  DOI ID：10.5511/plantbiotechnology.18.0507a
• Ferredoxin/thioredoxin system plays an important role in the chloroplastic NADP status of Arabidopsis.　　　　　　　　　　　　　　　
  Hashida SN; Miyagi A; Nishiyama M; Yoshida K; Hisabori T; Kawai-Yamada M
  The Plant journal : for cell and molecular biology, 巻：95, 号：6, 開始ページ：947, 終了ページ：960, 2018年09月, ［査読有り］
  DOI：https://doi.org/10.1111/tpj.14000
  DOI ID：10.1111/tpj.14000, ISSN：0960-7412, PubMed ID：29920827
• DSH5, a dihydrosphingosine C4 hydroxylase gene family member, shows spatially restricted expression in rice and is lethal when expressed ectopically.　　　　　　　　　　　　　　　
  Imamura T; Obata C; Yoneyama K; Ichikawa M; Ikura A; Mutsuro-Aoki H; Ishikawa T; Kawai-Yamada M; Sasaki T; Kusano H; Shimada H
  Genes & genetic systems, 巻：93, 号：4, 開始ページ：135, 終了ページ：142, 2018年09月, ［査読有り］, ［国内誌］
  Dihydrosphingosine C4 hydroxylase (DSH), a diiron-binding membrane enzyme, catalyzes the hydration of dihydrosphingosine and acyl-sphinganine to produce phytosphingosine and phytoceramide, respectively. Rice has two types of DSH homologs: general DSHs, namely DSH1, DSH2 and DSH4, and others that show spatial expression profiles, namely DSH3 and DSH5. The general DSHs exist in many plant species. These DSHs showed similarity in their functions and complemented the yeast sur2D mutation. In contrast, homologs of DSH3 and DSH5 were found only in monocot plants. Phylogenetic analysis placed these DSHs in different clades that are evolutionarily divergent from those of the general DSHs. DSH3 and DSH5 showed low-level expression. DSH5 expression was specifically in vascular bundle tissues. Ectopic expression of DSH5 induced a dwarf phenotype characterized by severe growth inhibition and an increase in the thickness of the leaf body caused by enlargement of bulliform cells in the leaves. However, no significant difference was observed in the amount of sphingolipid species. DSH5 did not complement the yeast sur2D mutation, implying that DSH5 has little effect on sphingolipid metabolism. These findings suggested that DSH3 and DSH5 originated and diverged in monocot plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1266/ggs.17-00054
  DOI ID：10.1266/ggs.17-00054, ISSN：1341-7568, PubMed ID：30185720
• Suppression of Arabidopsis GGLT1 affects growth by reducing the L-galactose content and borate cross-linking of rhamnogalacturonan-II.　　　　　　　　　　　　　　　
  Sechet J; Htwe S; Urbanowicz B; Agyeman A; Feng W; Ishikawa T; Colomes M; Kumar KS; Kawai-Yamada M; Dinneny JR; O'Neill MA; Mortimer JC
  The Plant journal : for cell and molecular biology, 2018年09月, ［査読有り］
  DOI：https://doi.org/10.1111/tpj.14088
  DOI ID：10.1111/tpj.14088, ISSN：0960-7412, PubMed ID：30203879
• Effects of inactivation of the cyAbrB2 transcription factor together with glycogen synthesis on cellular metabolism and free fatty acid production in the cyanobacterium Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Kodama Y; Kawahara A; Miyagi A; Ishikawa T; Kawai-Yamada M; Kaneko Y; Takimura Y; Hihara Y
  Biotechnology and bioengineering, 2018年09月, ［査読有り］
  DOI：https://doi.org/10.1002/bit.26842
  DOI ID：10.1002/bit.26842, ISSN：0006-3592, PubMed ID：30252943
• GLUCOSAMINE INOSITOLPHOSPHORYLCERAMIDE TRANSFERASE1 (GINT1) Is a GlcNAc-Containing Glycosylinositol Phosphorylceramide Glycosyltransferase.　　　　　　　　　　　　　　　
  Ishikawa T; Fang L; Rennie EA; Sechet J; Yan J; Jing B; Moore W; Cahoon EB; Scheller HV; Kawai-Yamada M; Mortimer JC
  Plant physiology, 巻：177, 号：3, 開始ページ：938, 終了ページ：952, 2018年07月, ［査読有り］
  DOI：https://doi.org/10.1104/pp.18.00396
  DOI ID：10.1104/pp.18.00396, ISSN：0032-0889, PubMed ID：29760197
• Effects of Elevated Atmospheric CO 2 on Respiratory Rates in Mature Leaves of Two Rice Cultivars Grown at a Free-Air CO 2 Enrichment Site and Analyses of the Underlying Mechanisms　　　　　　　　　　　　　　　
  Ko Noguchi; Tomonori Tsunoda; Atsuko Miyagi; Maki Kawai-Yamada; Daisuke Sugiura; Shin-Ichi Miyazawa; Takeshi Tokida; Yasuhiro Usui; Hirofumi Nakamura; Hidemitsu Sakai; Toshihiro Hasegawa
  Plant and Cell Physiology, 巻：59, 号：3, 開始ページ：637, 終了ページ：649, 2018年03月, ［査読有り］
  Respiratory CO 2 efflux and O 2 uptake rates in leaves change in response to the growth CO 2 concentration ([CO 2 ]). The degrees of change vary depending on the responses of cellular processes such as nitrogen (N) assimilation and accumulation of organic acids to growth [CO 2 ]. However, the underlying mechanisms remain unclear. Here, we examined the respiratory characteristics of mature leaves of two rice varieties with different yield capacities at different growth stages under ambient and elevated [CO 2 ] conditions at a free-air CO 2 enrichment site. We also examined the effect of increased water temperature on leaf respiration. We measured the rates of CO 2 efflux and O 2 uptake, and determined N contents, primary metabolite contents and maximal activities of respiratory enzymes. The leaf CO 2 efflux rates decreased in plants grown at elevated [CO 2 ] in both varieties, and were higher in high-yielding Takanari than in Koshihikari. The leaf O 2 uptake rates showed little change with respect to growth [CO 2 ] and variety. The increased water temperature did not significantly affect the CO 2 efflux and O 2 uptake rates. The N and amino acid contents were significantly higher in Takanari than in Koshihikari. The enhanced N assimilation in Takanari may have consumed more respiratory NADH, leading to higher CO 2 efflux rates. In Koshihikari, the ratio of tricarboxylic acid (TCA) cycle intermediates changed and maximal activities of enzymes in the TCA cycle decreased at elevated [CO 2 ]. Therefore, the decreased rates of CO 2 efflux in Koshihikari may be due to the decreased activities of TCA cycle enzymes at elevated [CO 2 ].
  Oxford University Press, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcy017
  DOI ID：10.1093/pcp/pcy017, ISSN：1471-9053, PubMed ID：29401364, SCOPUS ID：85043253711
• Evaluation of metabolic changes in oxalate-rich plant Rumex obtusifolius L. caused by ion beam irradiation.　　　　　　　　　　　　　　　
  Atsuko Miyagi; Sayaka Kitano; Yutaka Oono; Yoshihiro Hase; Issay Narumi; Masatoshi Yamaguchi; Hirofumi Uchimiya; Maki Kawai-Yamada
  Plant physiology and biochemistry : PPB, 巻：122, 開始ページ：40, 終了ページ：45, 2018年01月, ［査読有り］, ［国際誌］
  Some Rumex species such as sorrel are edible as baby leaf salad greens. On the other hand, Rumex plants accumulate soluble oxalate, a toxic metabolite which causes serious diseases such as renal syndrome. We attempted to produce low-oxalate plants of R. obtusifolius, a perennial weed which has higher vitamin C and amino acid content and higher tolerance to stress than many other Rumex species. Ion beams are ionising radiation with high linear energy transfer that causes a wide spectrum of mutations. Thus, in the present study we evaluated the effects of ion beams on oxalate and other primary metabolites in leaves of R. obtusifolius using CE-MS. The results showed that oxalate content was increased by irradiation with carbon ion beams. Metabolome analysis revealed that ion beams affected carbon flow to the isocitrate pathway, which is involved in oxalate synthesis. These observations suggested that modulation of carbon flow to the isocitrate pathway is important to regulate oxalate levels in plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.plaphy.2017.11.001
  DOI ID：10.1016/j.plaphy.2017.11.001, ISSN：0981-9428, PubMed ID：29172104
• Synergistic effects of light quality, carbon dioxide and nutrients on metabolite compositions of head lettuce under artificial growth conditions mimicking a plant factory　　　　　　　　　　　　　　　
  Atsuko Miyagi; Hirofumi Uchimiya; Maki Kawai-Yamada
  FOOD CHEMISTRY, 巻：218, 開始ページ：561, 終了ページ：568, 2017年03月, ［査読有り］
  Carbon dioxide (CO2), nutrient supply, and light quality are amongst the major controlling factors to improve the biomass production and nutritional outputs in plant factory. The present study employed CE-MS to investigate the effects of high CO2, nutrient formulation, and LED on the accumulation of primary metabolites in head lettuce. Results suggested that high CO2 (1000 ppm) and nutrient supply enhanced both the biomass and some amino acids. Hierarchical clustering analysis was used to evaluate effects of red LED in combination with high CO2 and Hoagland's formulation; distinctive cluster formation contained 14 amino acids (mostly branched-chain and aromatic amino acids, histidine and arginine). Thus, simultaneous treatments of monochromatic LED, high CO2 and nutrient formulation improved the amino acids accumulation, and likely reduced the inorganic nitrogen sources in planta. (C) 2016 Elsevier Ltd. All rights reserved.
  ELSEVIER SCI LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.foodchem.2016.09.102
  DOI ID：10.1016/j.foodchem.2016.09.102, ISSN：0308-8146, eISSN：1873-7072, ORCID：45646351, Web of Science ID：WOS:000386409700073
• CE–MS-based metabolomics reveals the metabolic profile of maitake mushroom (Grifola frondosa) strains with different cultivation characteristics　　　　　　　　　　　　　　　
  Mayumi Sato; Atsuko Miyagi; Shozo Yoneyama; Seiki Gisusi; Yoshihiko Tokuji; Maki Kawai-Yamada
  Bioscience, Biotechnology and Biochemistry, 巻：81, 号：12, 開始ページ：2314, 終了ページ：2322, 2017年, ［査読有り］
  Maitake mushroom (Grifola frondosa [Dicks.] Gray) is generally cultured using the sawdust of broadleaf trees. The maitake strain Gf433 has high production efficiency, with high-quality of fruiting bodies even when 30% of the birch sawdust on the basal substrate is replaced with conifer sawdust. We performed metabolome analysis to investigate the effect of different cultivation components on the metabolism of Gf433 and Mori52 by performing CE–MS on their fruiting bodies in different cultivation conditions to quantify the levels of amino acids, organic acids, and phosphorylated organic acids. We found that amino acid and organic acid content in Gf433 were not affected by the kind of sawdust. However, Gf433 contained more organic acids and less amino acids than Mori52, and Gf433 also contained more chitin compared with Mori52. We believe that these differences in the metabolome contents of the two strains are related to the high production efficiency of Gf433.
  Japan Society for Bioscience Biotechnology and Agrochemistry, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/09168451.2017.1387049
  DOI ID：10.1080/09168451.2017.1387049, ISSN：1347-6947, ORCID：45646350, PubMed ID：29050513, SCOPUS ID：85038389198, Web of Science ID：WOS:000423159400012
• Loss of Inositol Phosphorylceramide Sphingolipid Mannosylation Induces Plant Immune Responses and Reduces Cellulose Content in Arabidopsis　　　　　　　　　　　　　　　
  Lin Fang; Toshiki Ishikawa; Emilie A. Rennie; Gosia M. Murawska; Jeemeng Lao; Jingwei Yan; Alex Yi-Lin Tsai; Edward E. K. Baidoo; Jun Xu; Jay D. Keasling; Taku Demura; Maki Kawai-Yamada; Henrik V. Scheller; Jenny C. Mortimer
  PLANT CELL, 巻：28, 号：12, 開始ページ：2991, 終了ページ：3004, 2016年12月, ［査読有り］
  Glycosylinositol phosphorylceramides (GIPCs) are a class of glycosylated sphingolipids found in plants, fungi, and protozoa. These lipids are abundant in the plant plasma membrane, forming; 25% of total plasma membrane lipids. Little is known about the function of the glycosylated headgroup, but two recent studies have indicated that they play a key role in plant signaling and defense. Here, we show that a member of glycosyltransferase family 64, previously named ECTOPICALLY PARTING CELLS1, is likely a Golgi-localized GIPC-specific mannosyl-transferase, which we renamed GIPC MANNOSYL-TRANSFERASE1 (GMT1). Sphingolipid analysis revealed that the Arabidopsis thaliana gmt1 mutant almost completely lacks mannose-carrying GIPCs. Heterologous expression of GMT1 in Saccharomyces cerevisiae and tobacco (Nicotiana tabacum) cv Bright Yellow 2 resulted in the production of non-native mannosylated GIPCs. gmt1 displays a severe dwarfed phenotype and a constitutive hypersensitive response characterized by elevated salicylic acid and hydrogen peroxide levels, similar to that we previously reported for the Golgi-localized, GIPC-specific, GDP-Man transporter GONST1 (Mortimer et al., 2013). Unexpectedly, we show that gmt1 cell walls have a reduction in cellulose content, although other matrix polysaccharides are unchanged.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1105/tpc.16.00186
  DOI ID：10.1105/tpc.16.00186, ISSN：1040-4651, eISSN：1532-298X, ORCID：45646353, PubMed ID：27895225, Web of Science ID：WOS:000393167800009
• Molecular characterization and targeted quantitative profiling of the sphingolipidome in rice　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Yukihiro Ito; Maki Kawai-Yamada
  PLANT JOURNAL, 巻：88, 号：4, 開始ページ：681, 終了ページ：693, 2016年11月, ［査読有り］
  Recent advances in comprehensive metabolite profiling techniques, the foundation of metabolomics, is facilitating our understanding of the functions, regulation and complex networks of various metabolites in organisms. Here, we report a quantitative metabolomics technique for complex plant sphingolipids, composed of various polar head groups as well as structural isomers of hydrophobic ceramide moieties. Rice (Oryza sativa L.) was used as an experimental model of monocotyledonous plants and has been demonstrated to possess a highly complex sphingolipidome including hundreds of molecular species with a wide range of abundance. We established a high-throughput scheme for lipid preparation and mass spectrometry-based characterization of complex sphingolipid structures, which provided basic information to create a comprehensive theoretical library for targeted quantitative profiling of complex sphingolipids in rice. The established sphingolipidomic approach combined with multivariate analyses of the large dataset obtained clearly showed that different classes of rice sphingolipids, particularly including subclasses of glycosylinositol phosphoceramide with various sugar-chain head groups, are distributed with distinct quantitative profiles in various rice tissues, indicating tissue-dependent metabolism and biological functions of the lipid classes and subclasses. The sphingolipidomic analysis also highlighted that disruption of a lipid-associated gene causes a typical sphingolipidomic change in a gene-dependent manner. These results clearly support the utility of the sphingolipidomic approach in application to wide screening of sphingolipid-metabolic phenotypes as well as deeper investigation of metabolism and biological functions of complex sphingolipid species in plants.
  Significance Statement Sphingolipids play vital roles in plants, but the biological implications of their structural diversity remains to be addressed. Here we detail methodological advances for characterizing complex sphingolipid species quantitatively, and demonstrate its utility for profiling tissue-specific sphingolipids and for metabolic fingerprinting of sphingolipid-associated mutants.
  WILEY-BLACKWELL, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.13281
  DOI ID：10.1111/tpj.13281, ISSN：0960-7412, eISSN：1365-313X, ORCID：45646355, Web of Science ID：WOS:000389928200013
• Increased Rate of NAD Metabolism Shortens Plant Longevity by Accelerating Developmental Senescence in Arabidopsis　　　　　　　　　　　　　　　
  Shin-nosuke Hashida; Taketo Itami; Kentaro Takahara; Takayuki Hirabayashi; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANT AND CELL PHYSIOLOGY, 巻：57, 号：11, 開始ページ：2427, 終了ページ：2439, 2016年11月, ［査読有り］
  NAD is a well-known co-enzyme that mediates hundreds of redox reactions and is the basis of various processes regulating cell responses to different environmental and developmental cues. The regulatory mechanism that determines the amount of cellular NAD and the rate of NAD metabolism remains unclear. We created Arabidopsis thaliana plants overexpressing the NAD synthase (NADS) gene that participates in the final step of NAD biosynthesis. NADS overexpression enhanced the activity of NAD biosynthesis but not the amounts of NAD(+), NADH, NADP(+) or NADPH. However, the amounts of some intermediates were elevated, suggesting that NAD metabolism increased. The NAD redox state was greatly facilitated by an imbalance between NAD generation and degradation in response to bolting. Metabolite profiling and transcriptional analysis revealed that the drastic modulation of NAD redox homeostasis increased tricarboxylic acid flux, causing the ectopic generation of reactive oxygen species. Vascular bundles suffered from oxidative stress, leading to a malfunction in amino acid and organic acid transportation that caused early wilting of the flower stalk and shortened plant longevity, probably due to malnutrition. We concluded that the mechanism regulating the balance between NAD synthesis and degradation is important in the systemic plant response to developmental cues during the growth-phase transition.
  OXFORD UNIV PRESS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcw155
  DOI ID：10.1093/pcp/pcw155, ISSN：0032-0781, eISSN：1471-9053, ORCID：45646352, Web of Science ID：WOS:000393158000017
• Metabolomic analysis of NAD kinase-deficient mutants of the cyanobacterium Synechocystis sp PCC 6803　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Atsuko Miyagi; Yuto Haishima; Toshiki Ishikawa; Minoru Nagano; Masatoshi Yamaguchi; Yukako Hihara; Maki Kawai-Yamada
  JOURNAL OF PLANT PHYSIOLOGY, 巻：205, 開始ページ：105, 終了ページ：112, 2016年10月, ［査読有り］
  NAD kinase (NADK) phosphorylates NAD(H) to NADP(H). The enzyme has a crucial role in the regulation of the NADP(H)/NAD(H) ratio in various organisms. The unicellular cyanobacterium Synechocystis sp. PCC 6803 possesses two NADK-encoding genes, sll1415 and slr0400. To elucidate the metabolic change in NADK-deficient mutants growing under photoautotrophic conditions, we conducted metabolomic analysis using capillary electrophoresis mass spectrometry (CE-MS). The growth curves of the wild type parent (WT) and NADK-deficient mutants (Delta 1415 and Delta 0400) did not show any differences under photoautotrophic conditions. The NAD(P)(H) balance showed abnormality in both mutants. However, only the metabolite pattern of Delta 0400 showed differences compared to WT. These results indicated that the two NADK isoforms have distinct functions in cyanobacterial metabolism. (C) 2016 Elsevier GmbH. All rights reserved.
  ELSEVIER GMBH, URBAN & FISCHER VERLAG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2016.09.002
  DOI ID：10.1016/j.jplph.2016.09.002, ISSN：0176-1617, eISSN：1618-1328, ORCID：45646354, PubMed ID：27657983, Web of Science ID：WOS:000385858600014
• Plasma Membrane Microdomains Are Essential for Rac1-RbohB/H-Mediated Immunity in Rice　　　　　　　　　　　　　　　
  Minoru Nagano; Toshiki Ishikawa; Masayuki Fujiwara; Yoichiro Fukao; Yoji Kawano; Maki Kawai-Yamada; Ko Shimamoto
  PLANT CELL, 巻：28, 号：8, 開始ページ：1966, 終了ページ：1983, 2016年08月, ［査読有り］
  Numerous plant defense-related proteins are thought to congregate in plasma membrane microdomains, which consist mainly of sphingolipids and sterols. However, the extent to which microdomains contribute to defense responses in plants is unclear. To elucidate the relationship between microdomains and innate immunity in rice (Oryza sativa), we established lines in which the levels of sphingolipids containing 2-hydroxy fatty acids were decreased by knocking down two genes encoding fatty acid 2-hydroxylases (FAH1 and FAH2) and demonstrated that microdomains were less abundant in these lines. By testing these lines in a pathogen infection assay, we revealed that microdomains play an important role in the resistance to rice blast fungus infection. To illuminate the mechanism by which microdomains regulate immunity, we evaluated changes in protein composition, revealing that microdomains are required for the dynamics of the Rac/ROP small GTPase Rac1 and respiratory burst oxidase homologs (Rbohs) in response to chitin elicitor. Furthermore, FAHs are essential for the production of reactive oxygen species (ROS) after chitin treatment. Together with the observation that RbohB, a defense-related NADPH oxidase that interacts with Rac1, is localized in microdomains, our data indicate that microdomains are required for chitin-induced immunity through ROS signaling mediated by the Rac1-RbohB pathway.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1105/tpc.16.00201
  DOI ID：10.1105/tpc.16.00201, ISSN：1040-4651, eISSN：1532-298X, ORCID：45646356, Web of Science ID：WOS:000386169200016
• KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect L-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis　　　　　　　　　　　　　　　
  Shota Sawake; Noriaki Tajima; Jenny C. Mortimer; Jeemeng Lao; Toshiki Ishikawa; Xiaolan Yu; Yukiko Yamanashi; Yoshihisa Yoshimi; Maki Kawai-Yamada; Paul Dupree; Yoichi Tsumuraya; Toshihisa Kotake
  PLANT CELL, 巻：27, 号：12, 開始ページ：3397, 終了ページ：3409, 2015年12月, ［査読有り］
  Humans are unable to synthesize L-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1105/tpc.15.00379
  DOI ID：10.1105/tpc.15.00379, ISSN：1040-4651, eISSN：1532-298X, ORCID：45646361, Web of Science ID：WOS:000368297100010
• Glycosylated sphingolipid biosynthesis and function in Arabidopsis
  Jenny C. Mortimer; Toshiki Ishikawa; Lin Fang; Beibei Jing; Emilie Rennie; Noriko Inada; Xiaolan Yu; Jeemeng Lao; Taku Demura; Maki Kawai-Yamada; Henrik Scheller; Paul Dupree
  GLYCOBIOLOGY, 巻：25, 号：11, 開始ページ：1266, 終了ページ：1267, 2015年11月, ［査読有り］
  OXFORD UNIV PRESS INC, 英語
  ISSN：0959-6658, eISSN：1460-2423, ORCID：45646360, Web of Science ID：WOS:000362991500108
• Overexpression of BAX INHIBITOR-1 Links Plasma Membrane Microdomain Proteins to Stress　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Toshihiko Aki; Shuichi Yanagisawa; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANT PHYSIOLOGY, 巻：169, 号：2, 開始ページ：1333, 終了ページ：1343, 2015年10月, ［査読有り］
  BAX INHIBITOR-1 (BI-1) is a cell death suppressor widely conserved in plants and animals. Overexpression of BI-1 enhances tolerance to stress-induced cell death in plant cells, although the molecular mechanism behind this enhancement is unclear. We recently found that Arabidopsis (Arabidopsis thaliana) BI-1 is involved in the metabolism of sphingolipids, such as the synthesis of 2-hydroxy fatty acids, suggesting the involvement of sphingolipids in the cell death regulatory mechanism downstream of BI-1. Here, we show that BI-1 affects cell death-associated components localized in sphingolipid-enriched microdomains of the plasma membrane in rice (Oryza sativa) cells. The amount of 2-hydroxy fatty acid-containing glucosylceramide increased in the detergent-resistant membrane (DRM; a biochemical counterpart of plasma membrane microdomains) fraction obtained from BI-1-overexpressing rice cells. Comparative proteomics analysis showed quantitative changes of DRM proteins in BI-1-overexpressing cells. In particular, the protein abundance of FLOTILLIN HOMOLOG (FLOT) and HYPERSENSITIVE-INDUCED REACTION PROTEIN3 (HIR3) markedly decreased in DRM of BI-1-overexpressing cells. Loss-of-function analysis demonstrated that FLOT and HIR3 are required for cell death by oxidative stress and salicylic acid, suggesting that the decreased levels of these proteins directly contribute to the stress-tolerant phenotypes in BI-1-overexpressing rice cells. These findings provide a novel biological implication of plant membrane microdomains in stress-induced cell death, which is negatively modulated by BI-1 overexpression via decreasing the abundance of a set of key proteins involved in cell death.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.15.00445
  DOI ID：10.1104/pp.15.00445, ISSN：0032-0889, eISSN：1532-2548, ORCID：45646363, Web of Science ID：WOS:000365401000038
• Ethylene Biosynthesis Is Promoted by Very-Long-Chain Fatty Acids during Lysigenous Aerenchyma Formation in Rice Roots.　　　　　　　　　　　　　　　
  Takaki Yamauchi; Katsuhiro Shiono; Minoru Nagano; Aya Fukazawa; Miho Ando; Itsuro Takamure; Hitoshi Mori; Naoko K Nishizawa; Maki Kawai-Yamada; Nobuhiro Tsutsumi; Kiyoaki Kato; Mikio Nakazono
  Plant physiology, 巻：169, 号：1, 開始ページ：180, 終了ページ：93, 2015年09月, ［査読有り］, ［国際誌］
  In rice (Oryza sativa) roots, lysigenous aerenchyma, which is created by programmed cell death and lysis of cortical cells, is constitutively formed under aerobic conditions, and its formation is further induced under oxygen-deficient conditions. Ethylene is involved in the induction of aerenchyma formation. reduced culm number1 (rcn1) is a rice mutant in which the gene encoding the ATP-binding cassette transporter RCN1/OsABCG5 is defective. Here, we report that the induction of aerenchyma formation was reduced in roots of rcn1 grown in stagnant deoxygenated nutrient solution (i.e. under stagnant conditions, which mimic oxygen-deficient conditions in waterlogged soils). 1-Aminocyclopropane-1-carboxylic acid synthase (ACS) is a key enzyme in ethylene biosynthesis. Stagnant conditions hardly induced the expression of ACS1 in rcn1 roots, resulting in low ethylene production in the roots. Accumulation of saturated very-long-chain fatty acids (VLCFAs) of 24, 26, and 28 carbons was reduced in rcn1 roots. Exogenously supplied VLCFA (26 carbons) increased the expression level of ACS1 and induced aerenchyma formation in rcn1 roots. Moreover, in rice lines in which the gene encoding a fatty acid elongase, CUT1-LIKE (CUT1L; a homolog of the gene encoding Arabidopsis CUT1, which is required for cuticular wax production), was silenced, both ACS1 expression and aerenchyma formation were reduced. Interestingly, the expression of ACS1, CUT1L, and RCN1/OsABCG5 was induced predominantly in the outer part of roots under stagnant conditions. These results suggest that, in rice under oxygen-deficient conditions, VLCFAs increase ethylene production by promoting 1-aminocyclopropane-1-carboxylic acid biosynthesis in the outer part of roots, which, in turn, induces aerenchyma formation in the root cortex.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.15.00106
  DOI ID：10.1104/pp.15.00106, ORCID：45646359, PubMed ID：26036614, PubMed Central ID：PMC4577372, Web of Science ID：WOS:000360930600017
• Effects of water turbulence on variations in cell ultrastructure and metabolism of amino acids in the submersed macrophyte, Elodea nuttallii (Planch.) H. St. John　　　　　　　　　　　　　　　
  K. S. S. Atapaththu; A. Miyagi; K. Atsuzawa; Y. Kaneko; M. Kawai-Yamada; T. Asaeda
  PLANT BIOLOGY, 巻：17, 号：5, 開始ページ：997, 終了ページ：1004, 2015年09月, ［査読有り］
  The interactions between macrophytes and water movement are not yet fully understood, and the causes responsible for the metabolic and ultrastructural variations in plant cells as a consequence of turbulence are largely unknown. In the present study, growth, metabolism and ultrastructural changes were evaluated in the aquatic macrophyte Elodea nuttallii, after exposure to turbulence for 30days. The turbulence was generated with a vertically oscillating horizontal grid. The turbulence reduced plant growth, plasmolysed leaf cells and strengthened cell walls, and plants exposed to turbulence accumulated starch granules in stem chloroplasts. The size of the starch granules increased with the magnitude of the turbulence. Using capillary electrophoresis-mass spectrometry (CE-MS), analysis of the metabolome found metabolite accumulation in response to the turbulence. Asparagine was the dominant amino acid that was concentrated in stressed plants, and organic acids such as citrate, ascorbate, oxalate and -amino butyric acid (GABA) also accumulated in response to turbulence. These results indicate that turbulence caused severe stress that affected plant growth, cell ultrastructure and some metabolic functions of E.nuttallii. Our findings offer insights to explain the effects of water movement on the functions of aquatic plants.
  WILEY-BLACKWELL, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/plb.12346
  DOI ID：10.1111/plb.12346, ISSN：1435-8603, eISSN：1438-8677, ORCID：45646358, Web of Science ID：WOS:000359604800009
• Arabidopsis NAC domain proteins VND-INTERACTING1 and ANAC103 interact with multiple NAC domain proteins　　　　　　　　　　　　　　　
  Masatoshi Yamaguchi; Isura Sumeda Priyadarshana Nagahage; Misato Ohtani; Toshiki Ishikawa; Hirofumi Uchimiya; Maki Kawai-Yamada; Taku Demura
  PLANT BIOTECHNOLOGY, 巻：32, 号：2, 開始ページ：119, 終了ページ：U14, 2015年06月, ［査読有り］
  The Arabidopsis thaliana NAM, ATAF1/2 and CUC2 (NAC) domain transcription factor VND-INTERACTING1 (VNI1) was previously isolated as an interacting factor of VASCULAR-RELATED NAC-DOMAIN PROTEIN7 (VND7), a key regulator of xylem vessel differentiation, in a yeast two-hybrid screening. Here, we characterized VNI1 and its closest homolog, ANAC103, at the molecular level. Both VNI1 and ANAC103 interacted in vitro not only with VND proteins but also with other NAC domain proteins, such as NAC1 and CUC2. A transient expression assay showed that both VNI1 and ANAC103 are transcriptional activators. ANAC103 promoter activity was detected in vascular tissues, as well as in the trichomes, guard cells, and margins of young leaves. These data suggest that VNI1 and ANAC103 promote the differentiation of various types of cells by modulating the transcriptional activities of a wide range of NAC domain transcription factors.
  JAPANESE SOC PLANT CELL & MOLECULAR BIOLOGY, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.15.0208a
  DOI ID：10.5511/plantbiotechnology.15.0208a, ISSN：1342-4580, ORCID：45646357, Web of Science ID：WOS:000356970600002
• The effects of dark incubation on cellular metabolism of the wild type cyanobacterium Synechocystis sp. PCC 6803 and a mutant lacking the transcriptional regulator cyAbrB2.　　　　　　　　　　　　　　　
  Masamitsu Hanai; Yusuke Sato; Atsuko Miyagi; Maki Kawai-Yamada; Kyoko Tanaka; Yasuko Kaneko; Yoshitaka Nishiyama; Yukako Hihara
  Life, 巻：4, 号：4, 開始ページ：770, 終了ページ：787, 2014年11月, ［査読有り］, ［招待有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/life4040770
  DOI ID：10.3390/life4040770
• Does the Upstream Region Possessing MULE-Like Sequence in Rice Upregulate PsbS1 Gene Expression?　　　　　　　　　　　　　　　
  Mohammed Nuruzzaman; Tatsuo Kanno; Rika Amada; Yoshiki Habu; Ichiro Kasajima; Toshiki Ishikawa; Maki Kawai-Yamada; Hirofumi Uchimiya
  PLOS ONE, 巻：9, 号：9, 2014年09月, ［査読有り］
  The genomic nucleotide sequences of japonica rice (Sasanishiki and Nipponbare) contained about 2.7-kb unique region at the point of 0.4-kb upstream of the OsPsbS1 gene. In this study, we found that japonica rice with a few exceptions possessing such DNA sequences [denoted to OsMULE-japonica specific sequence (JSS)] is distinct by the presence of Mutator-like-element (MULE). Such sequence was absent in most of indica cultivars and Oryza glaberrima. In OsMULE-JSS1, we noted the presence of possible target site duplication (TSD; CTTTTCCAG) and about 80-bp terminal inverted repeat (TIR) near TSD. We also found the enhancement ofOsPsbS1 mRNA accumulation by intensified light, which was not associated with the DNA methylation status in OsMULE/JSS. In addition, O. rufipogon, possible ancestor of modern rice cultivars was found to compose PsbS gene of either japonica (minor) or indica (major) type. Transient gene expression assay showed that the japonica type promoter elevated a reporter gene activity than indica type.
  PUBLIC LIBRARY SCIENCE, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1371/journal.pone.0102742
  DOI ID：10.1371/journal.pone.0102742, ISSN：1932-6203, ORCID：45646368, Web of Science ID：WOS:000342685600002
• Effects of NAD kinase 2 overexpression on primary metabolite profiles in rice leaves under elevated carbon dioxide　　　　　　　　　　　　　　　
  Y. Onda; A. Miyagi; K. Takahara; H. Uchimiya; M. Kawai-Yamada
  PLANT BIOLOGY, 巻：16, 号：4, 開始ページ：819, 終了ページ：824, 2014年07月, ［査読有り］
  The concentration of carbon dioxide (CO2) in the atmosphere is projected to double by the end of the 21st century. In C-3 plants, elevated CO2 concentrations promote photosynthesis but inhibit the assimilation of nitrate into organic nitrogen compounds. Several steps of nitrate assimilation depend on the availability of ATP and sources of reducing power, such as nicotinamide adenine dinucleotide phosphate (NADPH). Plastid-localised NAD kinase 2 (NADK2) plays key roles in increasing the ATP/ADP and NADP(H)/NAD(H) ratios. Here we examined the effects of NADK2 overexpression on primary metabolism in rice (Oryza sativa) leaves in response to elevated CO2. By using capillary electrophoresis mass spectrometry, we showed that the primary metabolite profile of NADK2-overexpressing plants clearly differed from that of wild-type plants under ambient and elevated CO2. In NADK(2)-overexpressing leaves, expression of the genes encoding glutamine synthetase and glutamate synthase was up-regulated, and the levels of Asn, Gln, Arg, and Lys increased in response to elevated CO2. The present study suggests that overexpression of NADK2 promotes the biosynthesis of nitrogen-rich amino acids under elevated CO2.
  WILEY-BLACKWELL, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/plb.12131
  DOI ID：10.1111/plb.12131, ISSN：1435-8603, eISSN：1438-8677, ORCID：45646369, Web of Science ID：WOS:000337613000016
• Arabidopsis Bax inhibitor-1 promotes sphingolipid synthesis during cold stress by interacting with ceramide-modifying enzymes　　　　　　　　　　　　　　　
  Minoru Nagano; Toshiki Ishikawa; Yoshie Ogawa; Mitsuru Iwabuchi; Akari Nakasone; Ko Shimamoto; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANTA, 巻：240, 号：1, 開始ページ：77, 終了ページ：89, 2014年07月, ［査読有り］
  Bax inhibitor-1 (BI-1) is a widely conserved cell death suppressor localized in the endoplasmic reticulum membrane. Our previous results revealed that Arabidopsis BI-1 (AtBI-1) interacts with not only Arabidopsis cytochrome b (5) (Cb5), an electron transfer protein, but also a Cb5-like domain (Cb5LD)-containing protein, Saccharomyces cerevisiae fatty acid 2-hydroxylase 1, which 2-hydroxylates sphingolipid fatty acids. We have now found that AtBI-1 binds Arabidopsis sphingolipid Delta 8 long-chain base (LCB) desaturases AtSLD1 and AtSLD2, which are Cb5LD-containing proteins. The expression of both AtBI-1 and AtSLD1 was increased by cold exposure. However, different phenotypes were observed in response to cold treatment between an atbi-1 mutant and a sld1sld2 double mutant. To elucidate the reasons behind the difference, we analyzed sphingolipids and found that unsaturated LCBs in atbi-1 were not altered compared to wild type, whereas almost all LCBs in sld1sld2 were saturated, suggesting that AtBI-1 may not be necessary for the desaturation of LCBs. On the other hand, the sphingolipid content in wild type increased in response to low temperature, whereas total sphingolipid levels in atbi-1 were unaltered. In addition, the ceramide-modifying enzymes AtFAH1, sphingolipid base hydroxylase 2 (AtSBH2), acyl lipid desaturase 2 (AtADS2) and AtSLD1 were highly expressed under cold stress, and all are likely to be related to AtBI-1 function. These findings suggest that AtBI-1 contributes to synthesis of sphingolipids during cold stress by interacting with AtSLD1, AtFAH1, AtSBH2 and AtADS2.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00425-014-2065-7
  DOI ID：10.1007/s00425-014-2065-7, ISSN：0032-0935, eISSN：1432-2048, ORCID：45646364, Web of Science ID：WOS:000338318300005
• Development of an LC-MS/MS Method for the Analysis of Free Sphingoid Bases Using 4-Fluoro-7-nitrobenzofurazan (NBD-F)　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Hiroyuki Imai; Maki Kawai-Yamada
  LIPIDS, 巻：49, 号：3, 開始ページ：295, 終了ページ：304, 2014年03月, ［査読有り］
  The molecular species of sphingoid bases were tagged with the fluorescent amino group reagent, 4-fluoro-7-nitrobenzofurazan (NBD-F). The NBD-sphingoid bases were analyzed by a highly selective and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) technique capable of reliable detection of several fmol of the derivatives. Lipid extracts from plant samples were derivatized with NBD-F, and all nine species of free sphingoid bases present in plant sphingolipids were separated and quantified for the first time; a complete baseline resolution was achieved for cis-8 and trans-8 isomers of sphingoid bases by reversed phase HPLC on a C-18 column. The extraction and derivatization procedures and LC-MS/MS method can facilitate the progress of the studies for seeking the active components of sphingoid bases species in response to biological challenges.
  SPRINGER HEIDELBERG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11745-013-3871-6
  DOI ID：10.1007/s11745-013-3871-6, ISSN：0024-4201, eISSN：1558-9307, ORCID：45646367, Web of Science ID：WOS:000332665600009
• Culture temperature affects gene expression and metabolic pathways in the 2-methylisoborneol-producing cyanobacterium Pseudanabaena galeata　　　　　　　　　　　　　　　
  Masayuki Kakimoto; Toshiki Ishikawa; Atsuko Miyagi; Kazuaki Saito; Motonobu Miyazaki; Takashi Asaeda; Masatoshi Yamaguchi; Hirofumi Uchimiya; Maki Kawai-Yamada
  JOURNAL OF PLANT PHYSIOLOGY, 巻：171, 号：3-4, 開始ページ：292, 終了ページ：300, 2014年02月, ［査読有り］
  A volatile metabolite, 2-methylisoborneol (2-MIB), causes an unpleasant taste and odor in tap water. Some filamentous cyanobacteria produce 2-MIB via a two-step biosynthetic pathway: methylation of geranyl diphosphate (GPP) by methyl transferase (GPPMT), followed by the cyclization of methyl-GPP by monoterpene cyclase (MIBS). We isolated the genes encoding GPPMT and MIBS from Pseudanabaena galeata, a filamentous cyanobacterium known to be a major causal organism of 2-MIB production in Japanese lakes. The predicted amino acid sequence showed high similarity with that of Pseudanabaena limnetica (96% identity in GPPMT and 97% identity in MIBS). P. galeata was cultured at different temperatures to examine the effect of growth conditions on the production of 2-MIB and major metabolites. Gas chromatograph-mass spectrometry (GC-MS) measurements showed higher accumulation of 2-MIB at 30 degrees C than at 4 degrees C or 20 degrees C after 24 h of culture. Real-time-RT PCR analysis showed that the expression levels of the genes encoding GPPMT and MIBS decreased at 4 degrees C and increased at 30 degrees C, compared with at 20 degrees C. Furthermore, metabolite analysis showed dramatic changes in primary metabolite concentrations in cyanobacteria grown at different temperatures. The data indicate that changes in carbon flow in the TCA cycle affect 2-MIB biosynthesis at higher temperatures. (C) 2013 Elsevier GmbH. All rights reserved.
  ELSEVIER GMBH, URBAN & FISCHER VERLAG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2013.09.005
  DOI ID：10.1016/j.jplph.2013.09.005, ISSN：0176-1617, ORCID：45646366, Web of Science ID：WOS:000332052200013
• Advanced LC-MS/MS techniques dissecting diverse isomers of plant sphingolipid species.　　　　　　　　　　　　　　　
  Ishikawa T; Yanagawa D; Kawai-Yamada M; Imai H
  J. Anal. Bioanal. Tech., 巻：S5, 開始ページ：7, 2014年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.4172/2155-9872.S5-007
  DOI ID：10.4172/2155-9872.S5-007
• Plastidic protein Cdf1 is essential in Arabidopsis embryogenesis　　　　　　　　　　　　　　　
  Maki Kawai-Yamada; Minoru Nagano; Masayuki Kakimoto; Hirofumi Uchimiya
  PLANTA, 巻：239, 号：1, 開始ページ：39, 終了ページ：46, 2014年01月, ［査読有り］
  Arabidopsis cell growth defect factor-1 (Cdf1 in yeast, At5g23040) was originally isolated as a cell growth suppressor of yeast from genetic screening. To investigate the in vivo role of Cdf1 in plants, a T-DNA insertion line was analyzed. A homozygous T-DNA insertion mutant (cdf1/cdf1) was embryo lethal and showed arrested embryogenesis at the globular stage. The Cdf1 protein, when fused with green fluorescent protein, was localized to the plastid in stomatal guard cells and mesophyll cells. A promoter-beta-glucuronidase assay found expression of Cdf1 in the early heart stage of embryogenesis, suggesting that Cdf1 was essential for Arabidopsis embryogenesis during the transition of the embryo from the globular to heart stage.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00425-013-1966-1
  DOI ID：10.1007/s00425-013-1966-1, ISSN：0032-0935, eISSN：1432-2048, ORCID：45646370, Web of Science ID：WOS:000329240700003
• Arabidopsis glycerol-3-phosphate permease 4 is localized in the plastids and involved in the accumulation of seed oil　　　　　　　　　　　　　　　
  Hiromitsu Kawai; Toshiki Ishikawa; Toshiaki Mitsui; Shin Kore-eda; Maki Kawai-Yamada; Jun-ichi Ohnishi
  PLANT BIOTECHNOLOGY, 巻：31, 号：2, 開始ページ：159, 終了ページ：U80, 2014年, ［査読有り］
  In plant cells, glycerol 3-phosphate (G3P) is apparently able to permeate the plastid envelope, but no specific transporter has been characterized so far. The Arabidopsis five G3Pp proteins have been predicted as putative G3P permeases because of their high homologies with the prokaryotic G3P/phosphate antiporter GlpT. In the present study, G3Pp4 was characterized in detail utilizing reverse genetic approaches. Promoter analysis using GUS expression revealed that G3Pp4 was expressed strongly throughout the embryos during late developmental stages, and the seed lipid contents decreased in two g3pp4 knockout mutants. An enhanced yellow fluorescent protein-fused G3Pp4 was localized in the plastids, functioned physiologically in A. thaliana, and had G3P-transport activity in E. coli. These results suggest that Arabidopsis G3Pp4 is a plastid envelope-localized G3P transporter and involved in accumulation of storage lipids in late embryogenesis.
  JAPANESE SOC PLANT CELL & MOLECULAR BIOLOGY, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.14.0222a
  DOI ID：10.5511/plantbiotechnology.14.0222a, ISSN：1342-4580, ORCID：45646365, Web of Science ID：WOS:000339501900009
• Metabolic alterations in leaves of oxalate-rich plant Rumex obtusifolius L. irradiated by gamma rays　　　　　　　　　　　　　　　
  Sayaka Kitano; Atsuko Miyagi; Yutaka Oono; Yoshihiro Hase; Issay Narumi; Masatoshi Yamaguchi; Hirofumi Uchimiya; Maki Kawai-Yamada
  Metabolomics, 巻：11, 号：1, 開始ページ：134, 終了ページ：142, 2014年, ［査読有り］
  © 2014, Springer Science+Business Media New York. Oxalate in some plants is toxic to vertebrates and causes kidney failure. In the present study, we investigated on the metabolic effectiveness of gamma ray irradiation to seeds of Rumex obtusifolius, which are known to accumulate high level of soluble oxalate, to lower oxalate accumulation in leaves. Reduced rate of germination, discoloration of cotyledons, and deformed true leaves were observed by elevated irradiation. Metabolome analysis of primary metabolites using capillary electrophoresis–mass spectrometry showed a decrease in oxalate contents in the leaves of plants from gamma ray-irradiated seeds. Moreover, organic acids such as malate and 2-oxoglutarate also decreased, whereas amino acids such as glutamate and glutamine increased. These results indicated that seed irradiation by gamma rays leads to dynamic changes in metabolic pathways as well as plant growth/development.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-014-0684-4
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84939895666&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84939895666&origin=inward
  DOI ID：10.1007/s11306-014-0684-4, ISSN：1573-3882, eISSN：1573-3890, ORCID：45646362, SCOPUS ID：84939895666, Web of Science ID：WOS:000348343300013
• Rapid Induction of Lipid Droplets in Chlamydomonas reinhardtii and Chlorella vulgaris by Brefeldin A　　　　　　　　　　　　　　　
  Sangwoo Kim; Hanul Kim; Donghwi Ko; Yasuyo Yamaoka; Masumi Otsuru; Maki Kawai-Yamada; Toshiki Ishikawa; Hee-Mock Oh; Ikuo Nishida; Yonghua Li-Beisson; Youngsook Lee
  PLOS ONE, 巻：8, 号：12, 2013年12月, ［査読有り］
  Algal lipids are the focus of intensive research because they are potential sources of biodiesel. However, most algae produce neutral lipids only under stress conditions. Here, we report that treatment with Brefeldin A (BFA), a chemical inducer of ER stress, rapidly triggers lipid droplet (LD) formation in two different microalgal species, Chlamydomonas reinhardtii and Chlorella vulgaris. LD staining using Nile red revealed that BFA-treated algal cells exhibited many more fluorescent bodies than control cells. Lipid analyses based on thin layer chromatography and gas chromatography revealed that the additional lipids formed upon BFA treatment were mainly triacylglycerols (TAGs). The increase in TAG accumulation was accompanied by a decrease in the betaine lipid diacylglyceryl N,N,N-trimethylhomoserine (DGTS), a major component of the extraplastidic membrane lipids in Chlamydomonas, suggesting that at least some of the TAGs were assembled from the degradation products of membrane lipids. Interestingly, BFA induced TAG accumulation in the Chlamydomonas cells regardless of the presence or absence of an acetate or nitrogen source in the medium. This effect of BFA in Chlamydomonas cells seems to be due to BFA-induced ER stress, as supported by the induction of three homologs of ER stress marker genes by the drug. Together, these results suggest that ER stress rapidly triggers TAG accumulation in two green microalgae, C. reinhardtii and C. vulgaris. A further investigation of the link between ER stress and TAG synthesis may yield an efficient means of producing biofuel from algae.
  PUBLIC LIBRARY SCIENCE, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1371/journal.pone.0081978
  DOI ID：10.1371/journal.pone.0081978, ISSN：1932-6203, ORCID：45646376, Web of Science ID：WOS:000328734200021
• Metabolome analysis of food-chain between plants and insects　　　　　　　　　　　　　　　
  Atsuko Miyagi; Maki Kawai-Yamada; Minori Uchimiya; Noriyuki Ojima; Koichi Suzuki; Hirofumi Uchimiya
  METABOLOMICS, 巻：9, 号：6, 開始ページ：1254, 終了ページ：1261, 2013年12月, ［査読有り］
  Evolution has shown the co-dependency between host plants and predators (insects), especially inevitable dependency of predators on plant biomass for securing their energy sources. It was postulated that NAD(+) source used for major energy producing pathway is the glycerol-3-phosphate shuttle in insects. Using high throughput metabolomics approach, we found that larva of leaf beetle (Gastrophysa atrocyanea), which feed oxalate-rich plants (Rumex obtusifolius), possessed a unique mechanism for accumulating unusually high amounts of lactate. Similarly, larva of butterfly (Papilio machaon) fed with fennel (Foeniculum vulgare) accumulated lactate. Same butterfly also showed the elevated level of glycerol-3-phosphate equivalent to lactate. These evidences provide new insights into the mechanism underlying metabolite alteration between host plants and insect herbivores.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-013-0542-9
  DOI ID：10.1007/s11306-013-0542-9, ISSN：1573-3882, eISSN：1573-3890, ORCID：45646374, Web of Science ID：WOS:000326926700012
• Deletion of the Transcriptional Regulator cyAbrB2 Deregulates Primary Carbon Metabolism in Synechocystis sp PCC 6803　　　　　　　　　　　　　　　
  Yuki Kaniya; Ayumi Kizawa; Atsuko Miyagi; Maki Kawai-Yamada; Hirofumi Uchimiya; Yasuko Kaneko; Yoshikata Nishiyama; Yukako Hihara
  PLANT PHYSIOLOGY, 巻：162, 号：2, 開始ページ：1153, 終了ページ：1163, 2013年06月, ［査読有り］
  cyAbrB is a transcriptional regulator unique to and highly conserved among cyanobacterial species. A gene-disrupted mutant of cyabrB2 (sll0822) in Synechocystis sp. PCC 6803 exhibited severe growth inhibition and abnormal accumulation of glycogen granules within cells under photomixotrophic conditions. Within 6 h after the shift to photomixotrophic conditions, sodium bicarbonate-dependent oxygen evolution activity markedly declined in the Delta cyabrB2 mutant, but the decrease in methyl viologen-dependent electron transport activity was much smaller, indicating inhibition in carbon dioxide fixation. Decreases in the transcript levels of several genes related to sugar catabolism, carbon dioxide fixation, and nitrogen metabolism were also observed within 6 h. Metabolome analysis by capillary electrophoresis mass spectrometry revealed that several metabolites accumulated differently in the wild-type and mutant strains. For example, the amounts of pyruvate and 2-oxoglutarate (2OG) were significantly lower in the mutant than in the wild type, irrespective of trophic conditions. The growth rate of the Delta cyabrB2 mutant was restored to a level comparable to that under photoautotrophic conditions by addition of 2OG to the growth medium under photomixotrophic conditions. Activities of various metabolic processes, including carbon dioxide fixation, respiration, and nitrogen assimilation, seemed to be enhanced by 2OG addition. These observations suggest that cyAbrB2 is essential for the active transcription of genes related to carbon and nitrogen metabolism upon a shift to photomixotrophic conditions. Deletion of cyAbrB2 is likely to deregulate the partition of carbon between storage forms and soluble forms used for biosynthetic purposes. This disorder may cause inactivation of cellular metabolism, excess accumulation of reducing equivalents, and subsequent loss of viability under photomixotrophic conditions.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.113.218784
  DOI ID：10.1104/pp.113.218784, ISSN：0032-0889, ORCID：45646372, Web of Science ID：WOS:000319819900047
• An antagonist treatment in combination with tracer experiments revealed isocitrate pathway dominant to oxalate biosynthesis in Rumex obtusifolius L.　　　　　　　　　　　　　　　
  Atsuko Miyagi; Minori Uchimiya; Maki Kawai-Yamada; Hirofumi Uchimiya
  METABOLOMICS, 巻：9, 号：3, 開始ページ：590, 終了ページ：598, 2013年06月, ［査読有り］
  Oxalate accumulates in leaves of certain plants such as Rumex species (Polygonaceae). Oxalate plays important roles in defense to predator, detoxification of metallic ions, and in hydrogen peroxide formation upon wounding/senescence. However, biosynthetic pathways of soluble oxalate are largely unknown. In the present study we analysed Rumex obtusifolius L. treated with itaconate (an antagonist to isocitrate). Comprehensive metabolome analysis using capillary electrophoresis-mass spectrometry showed that oxalate content of "new leaves" was notably down-regulated by itaconate, as opposed to the accumulation of citrate. The (CO2)-C-13 feeding experiment revealed that oxalate accumulation in new leaves was affected by citrate translocation from stems. The results suggested that excess oxalate in new leaves of R. obtusifolius was synthesized primarily via the isocitrate pathway utilizing citrate delivered from stems.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-012-0486-5
  DOI ID：10.1007/s11306-012-0486-5, ISSN：1573-3882, ORCID：45646371, Web of Science ID：WOS:000318905100007
• NAD⁺ accumulation as a metabolic off switch for orthodox pollen.　　　　　　　　　　　　　　　
  Hashida SN; Kawai-Yamada M; Uchimiya H
  Plant signaling & behavior, 巻：8, 号：5, 開始ページ：e23937, 2013年05月, ［査読有り］
  DOI：https://doi.org/10.4161/psb.23937
  DOI ID：10.4161/psb.23937, ISSN：1559-2316, PubMed ID：23428890
• Accelerated NAD metabolism reveals the essential role of NADH/NAD ratio on onset of senescence and carbon stock redistribution in Arabidopsis
  HASHIDA Shin‐nosuke; KITAZAKI Kazuyoshi; SHOJI Kazuhiro; GOTO Fumiyuki; YOSHIHARA Toshihiro; KAWAI‐YAMADA Maki; UCHIMIYA Hirofumi
  日本植物生理学会年会要旨集, 巻：54th, 開始ページ：244, 2013年03月
  英語
  J-Global ID：201302281097335366
• Impact of aluminium stress on oxalate and other metabolites in Rumex obtusifolius　　　　　　　　　　　　　　　
  A. Miyagi; M. Uchimiya; M. Kawai-Yamada; H. Uchimiya
  WEED RESEARCH, 巻：53, 号：1, 開始ページ：30, 終了ページ：41, 2013年02月, ［査読有り］
  To understand alterations of oxalate and other metabolite levels induced by aluminium ion (Al3+) stress in Rumex plants, we measured the metabolites in R. obtusifolius using the capillary electrophoresismass spectrometry. Oxalate and its precursors (isocitrate and citrate) accumulated in leaves of R. obtusifolius after the Al3+ treatment at pH 4.5. Such increase was not observed under the acidic condition (pH 4.5) without Al3+. Principal component analysis showed organ-specific changes in metabolite levels in R. obtusifolius by the Al3+ treatment. Highly positive correlations between oxalate and its precursors were revealed by hierarchical clustering and correlation analyses. An increase in oxalate content was consistently observed for three Rumex species (R. obtusifolius, R. crispus and R. japonicus) grown in the presence of Al3+. On the other hand, multivariate analyses revealed the differential alterations of other metabolite levels between R. obtusifolius and the other two Rumex species.
  WILEY-BLACKWELL, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/j.1365-3180.2012.00949.x
  DOI ID：10.1111/j.1365-3180.2012.00949.x, ISSN：0043-1737, ORCID：45646373, Web of Science ID：WOS:000312996900004
• Effect of gamma ray irradiation on Rumex obtusifolius L.　　　　　　　　　　　　　　　
  Sayaka Kitano; Atsuko Miyagi; Yutaka Oono; Yoshihiro Hase; Issay Narumi; Hirofumi Uchimiya; Maki Kawai-Yamada
  JAEA Takasaki Annual Report 2011, 開始ページ：101, 2013年01月
• The role of plant bax inhibitor-1 in suppressing H2O 2-induced cell death　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Hirofumi Uchimiya; Maki Kawai-Yamada
  Methods in Enzymology, 巻：527, 開始ページ：239, 終了ページ：256, 2013年, ［査読有り］
  Hydrogen peroxide (H2O2) is known to be a typical endogenous signaling molecule that triggers programmed cell death in plants and metazoan. In this respect, they seem to share the mechanism of cell death caused by H2O2 and other reactive oxygen species (ROS). Bax inhibitor-1 (BI-1) is a well-conserved protein in plants and animals that serves as the inhibitor of mammalian proapoptotic proteins as well as plant ROS-induced cell death. As a target of H2O2, mitochondrion is considered to be an organelle of the primary ROS generation and perception. Thus, analysis of mitochondrial behavior in relation to functional roles of regulatory proteins (e.g., BI-1) will lead us to understand the core mechanisms of cell death regulation conserved in eukaryotes. In this chapter, we first introduce techniques of analyzing H2O2- (and ROS-) mediated changes in mitochondrial behavior. Next, we describe our understanding of the functions of plant BI-1 in regulation of ROS-induced cell death, with a technical basis for assessment of tolerance to ROS-mediated cell death in model plant systems. © 2013 Elsevier Inc.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/B978-0-12-405882-8.00013-1
  DOI ID：10.1016/B978-0-12-405882-8.00013-1, ISSN：0076-6879, ORCID：45646377, PubMed ID：23830635, SCOPUS ID：84879857652, Web of Science ID：WOS:000322846400014
• NAD(+) Accumulation during Pollen Maturation in Arabidopsis Regulating Onset of Germination　　　　　　　　　　　　　　　
  Shin-nosuke Hashida; Hideyuki Takahashi; Kentaro Takahara; Maki Kawai-Yamada; Kazuyoshi Kitazaki; Kazuhiro Shoji; Fumiyuki Goto; Toshihiro Yoshihara; Hirofumi Uchimiya
  MOLECULAR PLANT, 巻：6, 号：1, 開始ページ：216, 終了ページ：225, 2013年01月, ［査読有り］
  Although the nicotinamide nucleotides NAD(H) and NADP(H) are essential for various metabolic reactions that play major roles in maintenance of cellular homeostasis, the significance of NAD biosynthesis is not well understood. Here, we investigated the dynamics of pollen nicotinamide nucleotides in response to imbibition, a representative germination cue. Metabolic analysis with capillary electrophoresis electrospray ionization mass spectrometry revealed that excess amount of NAD(+) is accumulated in freshly harvested dry pollen, whereas it dramatically decreased immediately after contact with water. Importantly, excess of NAD(+) impaired pollen tube growth. Moreover, NAD(+) accumulation was retained after pollen was imbibed in the presence of NAD(+)-consuming reaction inhibitors and pollen germination was greatly retarded. Pollen deficient in the nicotinate/nicotinamide mononucleotide adenyltransferase (NMNAT) gene, encoding a key enzyme in NAD biosynthesis, and a lack of NAD(+) accumulation in the gametophyte, showed precocious pollen tube germination inside the anther locule and vigorous tube growth under high-humidity conditions. Hence, the accumulation of excess NAD(+) is not essential for pollen germination, but instead participates in regulating the timing of germination onset. These results indicate that NAD(+) accumulation acts to negatively regulate germination and a decrease in NAD(+) plays an important role in metabolic state transition.
  OXFORD UNIV PRESS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/mp/sss071
  DOI ID：10.1093/mp/sss071, ISSN：1674-2052, ORCID：45646375, Web of Science ID：WOS:000314117100022
• SMALL ACICIC PROTEIN1 Acts with RUB Modification Components, the COP9 Signalosome and AXR1 to Regulate Growth and Development of Arabidopsis (vol 160, pg 93, 2012)　　　　　　　　　　　　　　　
  A. Nakasone; M. Fujiwara; Y. Fukao; K. K. Biswas; A. Rahman; M. Kawai-Yamada; Narumi, I; H. Uchimiya; Y. Oono
  PLANT PHYSIOLOGY, 巻：160, 号：3, 開始ページ：1674, 終了ページ：1674, 2012年11月, ［査読有り］
  AMER SOC PLANT BIOLOGISTS, 英語
  DOI：https://doi.org/10.1104/pp.112.900448
  DOI ID：10.1104/pp.112.900448, ISSN：0032-0889, ORCID：45646378, Web of Science ID：WOS:000310584200039
• SMALL ACIDIC PROTEIN1 acts with RUB modification components, the COP9 signalosome, and AXR1 to regulate growth and development of Arabidopsis.　　　　　　　　　　　　　　　
  Akari Nakasone; Masayuki Fujiwara; Yoichiro Fukao; Kamal Kanti Biswas; Abidur Rahman; Maki Kawai-Yamada; Issay Narumi; Hirofumi Uchimiya; Yutaka Oono
  Plant physiology, 巻：160, 号：1, 開始ページ：93, 終了ページ：105, 2012年09月, ［査読有り］, ［国際誌］
  Previously, a dysfunction of the SMALL ACIDIC PROTEIN1 (SMAP1) gene was identified as the cause of the anti-auxin resistant1 (aar1) mutant of Arabidopsis (Arabidopsis thaliana). SMAP1 is involved in the response pathway of synthetic auxin, 2,4-dichlorophenoxyacetic acid, and functions upstream of the auxin/indole-3-acetic acid protein degradation step in auxin signaling. However, the exact mechanism by which SMAP1 functions in auxin signaling remains unknown. Here, we demonstrate that SMAP1 is required for normal plant growth and development and the root response to indole-3-acetic acid or methyl jasmonate in the auxin resistant1 (axr1) mutation background. Deletion analysis and green fluorescent protein/glutathione S-transferase pull-down assays showed that SMAP1 physically interacts with the CONSTITUTIVE PHOTOMORPHOGENIC9 SIGNALOSOME (CSN) via the SMAP1 F/D region. The extremely dwarf phenotype of the aar1-1 csn5a-1 double mutant confirms the functional role of SMAP1 in plant growth and development under limiting CSN functionality. Our findings suggest that SMAP1 is involved in the auxin response and possibly in other cullin-RING ubiquitin ligase-regulated signaling processes via its interaction with components associated with RELATED TO UBIQUITIN modification.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.111.188409
  DOI ID：10.1104/pp.111.188409, ORCID：45646379, PubMed ID：22576848, PubMed Central ID：PMC3440233, Web of Science ID：WOS:000308675100011
• Arabidopsis Sphingolipid Fatty Acid 2-Hydroxylases (AtFAH1 and AtFAH2) Are Functionally Differentiated in Fatty Acid 2-Hydroxylation and Stress Responses　　　　　　　　　　　　　　　
  Nagano, M; Takahara, K; Fujimoto, M; Tsutsumi, N; Uchimiya, H; Kawai-Yamada, M
  PLANT PHYSIOLOGY, 巻：159, 号：3, 開始ページ：1138, 終了ページ：1148, 2012年07月, ［査読有り］
  2-Hydroxy fatty acids (2-HFAs) are predominantly present in sphingolipids and have important physicochemical and physiological functions in eukaryotic cells. Recent studies from our group demonstrated that sphingolipid fatty acid 2-hydroxylase (FAH) is required for the function of Arabidopsis (Arabidopsis thaliana) Bax inhibitor-1 (AtBI-1), which is an endoplasmic reticulum membrane-localized cell death suppressor. However, little is known about the function of two Arabidopsis FAH homologs (AtFAH1 and AtFAH2), and it remains unclear whether 2-HFAs participate in cell death regulation. In this study, we found that both AtFAH1 and AtFAH2 had FAH activity, and the interaction with Arabidopsis cytochrome b(5) was needed for the sufficient activity. 2-HFA analysis of AtFAH1 knockdown lines and atfah2 mutant showed that AtFAH1 mainly 2-hydroxylated very-long-chain fatty acid (VLCFA), whereas AtFAH2 selectively 2-hydroxylated palmitic acid in Arabidopsis. In addition, 2-HFAs were related to resistance to oxidative stress, and AtFAH1 or 2-hydroxy VLCFA showed particularly strong responses to oxidative stress. Furthermore, AtFAH1 interacted with AtBI-1 via cytochrome b(5) more preferentially than AtFAH2. Our results suggest that AtFAH1 and AtFAH2 are functionally different FAHs, and that AtFAH1 or 2-hydroxy VLCFA is a key factor in AtBI-1-mediated cell death suppression.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.112.199547
  DOI ID：10.1104/pp.112.199547, ISSN：0032-0889, eISSN：1532-2548, Web of Science ID：WOS:000305958000022
• Gsp1 triggers the sexual developmental program including inheritance of chloroplast DNA and mitochondrial DNA in Chlamydomonas reinhardtii.　　　　　　　　　　　　　　　
  Nishimura Y; Shikanai T; Nakamura S; Kawai-Yamada M; Uchimiya H
  The Plant cell, 巻：24, 号：6, 開始ページ：2401, 終了ページ：2414, 2012年06月, ［査読有り］
  DOI：https://doi.org/10.1105/tpc.112.097865
  DOI ID：10.1105/tpc.112.097865, ISSN：1040-4651, PubMed ID：22715041
• Nitrate addition alleviates ammonium toxicity without lessening ammonium accumulation, organic acid depletion and inorganic cation depletion in Arabidopsis thaliana shoots.　　　　　　　　　　　　　　　
  Hachiya T; Watanabe CK; Fujimoto M; Ishikawa T; Takahara K; Kawai-Yamada M; Uchimiya H; Uesono Y; Terashima I; Noguchi K
  Plant & cell physiology, 巻：53, 号：3, 開始ページ：577, 終了ページ：591, 2012年03月, ［査読有り］
  Oxford University Press, 英語
  DOI ID：10.1093/pcp/pcs012, ISSN：0032-0781, CiNii Articles ID：10030309550, CiNii Books ID：AA0077511X, PubMed ID：22318863, Web of Science ID：WOS:000301359500008
• Plant sphingolipid fatty acid 2-hydroxylases have unique characters unlike their animal and fungus counterparts　　　　　　　　　　　　　　　
  Minoru Nagano; Hirofumi Uchimiya; Maki Kawai-Yamada
  Plant Signaling and Behavior, 巻：7, 号：11, 2012年, ［査読有り］
  2-Hydroxy fatty acids mainly contained in sphingolipids are synthesized by a sphingolipid fatty acid 2-hydroxylase (FAH). Recently, two FAH homologs in Arabidopsis thaliana (AtFAH1 and AtFAH2), without any cytochrome b5(Cb5)-like domains, which are essential for the function of Saccharomyces cerevisiae and mammalian FAH, were identified and both AtFAHs were shown to be activated by the interaction with Cb5. In this study, we compared FAHs of various plants, animals and fungi. Interestingly, only plants had two FAH homologs and none of plant FAHs had any Cb5-like domains. In addition, we showed from the interaction and expression analyses that AtFAHs interacted with multiple Cb5s probably in various tissues. Thus, plant FAHs may have evolved unlike animal and fungus FAHs. © 2012 Landes Bioscience.
  Landes Bioscience, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.4161/psb.21825
  DOI ID：10.4161/psb.21825, ISSN：1559-2324, PubMed ID：22918503, SCOPUS ID：84868513722
• Fate of C-13 in metabolic pathways and effects of high CO2 on the alteration of metabolites in Rumex obtusifolius L.　　　　　　　　　　　　　　　
  Atsuko Miyagi; Kentaro Takahara; Ichiro Kasajima; Hideyuki Takahashi; Maki Kawai-Yamada; Hirofumi Uchimiya
  METABOLOMICS, 巻：7, 号：4, 開始ページ：524, 終了ページ：535, 2011年12月, ［査読有り］
  In present study, in vivo turn-over of (CO2)-C-13 to organic acids such as oxalate and citrate in Rumex obtusifolius L. was explored. Conversion of fixed carbon to oxalate was studies using "new leaves", i.e., leaves removed from 2-month-old-plants grown under different environmental conditions. Collected new leaves and stems were subjected to metabolomic analyses using capillary electrophoresis mass spectrometry. The results showed the mobilization of metabolites from stems to new leaves, where active TCA cycle and oxalate pathways occurred. The C-13 labeling experiments also indicated that these pathways are active in new leaves. Subsequently, we compared the effects of high carbon dioxide level (1000 ppm) and nutrients (Hoagland's formulation) on the metabolite accumulation in R. obtusifolius. Data analysed by both principal component and hierarchical clustering analyses revealed significant changes in metabolite accumulation. The accumulation of most abundant metabolite oxalate in leaves was affected by both high CO2 as the carbon source and nutrients. We suggest that the common weed R. obtusifolius may proliferate in cultivated lands under high CO2 level, a potential cause of global warming.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-010-0272-1
  DOI ID：10.1007/s11306-010-0272-1, ISSN：1573-3882, ORCID：45646382, Web of Science ID：WOS:000295991900006
• Morphological classification of plant cell deaths　　　　　　　　　　　　　　　
  W. G. van Doorn; E. P. Beers; J. L. Dangl; V. E. Franklin-Tong; P. Gallois; I. Hara-Nishimura; A. M. Jones; M. Kawai-Yamada; E. Lam; J. Mundy; L. A. J. Mur; M. Petersen; A. Smertenko; M. Taliansky; F. Van Breusegem; T. Wolpert; E. Woltering; B. Zhivotovsky; P. V. Bozhkov
  CELL DEATH AND DIFFERENTIATION, 巻：18, 号：8, 開始ページ：1241, 終了ページ：1246, 2011年08月, ［査読有り］
  Programmed cell death (PCD) is an integral part of plant development and of responses to abiotic stress or pathogens. Although the morphology of plant PCD is, in some cases, well characterised and molecular mechanisms controlling plant PCD are beginning to emerge, there is still confusion about the classification of PCD in plants. Here we suggest a classification based on morphological criteria. According to this classification, the use of the term 'apoptosis' is not justified in plants, but at least two classes of PCD can be distinguished: vacuolar cell death and necrosis. During vacuolar cell death, the cell contents are removed by a combination of autophagy-like process and release of hydrolases from collapsed lytic vacuoles. Necrosis is characterised by early rupture of the plasma membrane, shrinkage of the protoplast and absence of vacuolar cell death features. Vacuolar cell death is common during tissue and organ formation and elimination, whereas necrosis is typically found under abiotic stress. Some examples of plant PCD cannot be ascribed to either major class and are therefore classified as separate modalities. These are PCD associated with the hypersensitive response to biotrophic pathogens, which can express features of both necrosis and vacuolar cell death, PCD in starchy cereal endosperm and during self-incompatibility. The present classification is not static, but will be subject to further revision, especially when specific biochemical pathways are better defined. Cell Death and Differentiation (2011) 18, 1241-1246; doi:10.1038/cdd.2011.36; published online 15 April 2011
  NATURE PUBLISHING GROUP, 英語
  DOI：https://doi.org/10.1038/cdd.2011.36
  DOI ID：10.1038/cdd.2011.36, ISSN：1350-9047, eISSN：1476-5403, ORCID：45646384, Web of Science ID：WOS:000292634000002
• Molecular distinction in genetic regulation of nonphotochemical quenching in rice　　　　　　　　　　　　　　　
  Ichiro Kasajima; Kaworu Ebana; Toshio Yamamoto; Kentaro Takahara; Masahiro Yano; Maki Kawai-Yamada; Hirofumi Uchimiya
  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 巻：108, 号：33, 開始ページ：13835, 終了ページ：13840, 2011年08月, ［査読有り］
  Nonphotochemical quenching (NPQ) regulates energy conversion in photosystem II and protects plants from photoinhibition. Here we analyze NPQ capacity in a number of rice cultivars. NPQ was strongly induced under medium and high light intensities in rice leaves. Japonica cultivars generally showed higher NPQ capacities than Indica cultivars when we measured a rice core collection. We mapped NPQ regulator and identified a locus (qNPQ1-2) that seems to be responsible for the difference in NPQ capacity between Indica and Japonica. One of the two rice PsbS homologues (OsPsbS1) was found within the qNPQ1-2 region. PsbS protein was not accumulated in the leaf blade of the mutant harboring transferred DNA insertion in OsPsbS1. NPQ capacity increased as OsPsbS1 expression increased in a series of transgenic lines ectopically expressing OsPsbS1 in an Indica cultivar. Indica cultivars lack a 2.7-kb region at the point 0.4 kb upstream of the OsPsbS1 gene, suggesting evolutionary discrimination of this gene.
  NATL ACAD SCIENCES, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1073/pnas.1104809108
  DOI ID：10.1073/pnas.1104809108, ISSN：0027-8424, ORCID：45646383, Web of Science ID：WOS:000293895100091
• Bax inhibitor-1: a highly conserved endoplasmic reticulum-resident cell death suppressor　　　　　　　　　　　　　　　
  T. Ishikawa; N. Watanabe; M. Nagano; M. Kawai-Yamada; E. Lam
  CELL DEATH AND DIFFERENTIATION, 巻：18, 号：8, 開始ページ：1271, 終了ページ：1278, 2011年08月, ［査読有り］
  In spite of fundamental differences between plant and animal cells, it is remarkable that some cell death regulators that were identified to control cell death in metazoans can also function in plants. The fact that most of these proteins do not have structural homologs in plant genomes suggests that they may be targeting a highly conserved 'core' mechanism with conserved functions that is present in all eukaryotes. The ubiquitous Bax inhibitor-1 (BI-1) is a common cell death suppressor in eukaryotes that has provided a potential portal to this cell death core. In this review, we will update the current status of our understanding on the function and activities of this intriguing protein. Genetic, molecular and biochemical studies have so far suggested a consistent view that BI-1 is an endoplasmic reticulum (ER)-resident transmembrane protein that can interact with multiple partners to alter intracellular Ca(2+) flux control and lipid dynamics. Functionally, the level of BI-1 protein has been hypothesized to have the role of a rheostat to regulate the threshold of ER-stress inducible cell death. Further, delineation of the cell death suppression mechanism by BI-1 should shed light on an ancient cell death core-control pathway in eukaryotes, as well as novel ways to improve stress tolerance. Cell Death and Differentiation (2011) 18, 1271-1278; doi:10.1038/cdd.2011.59; published online 20 May 2011
  NATURE PUBLISHING GROUP, 英語
  DOI：https://doi.org/10.1038/cdd.2011.59
  DOI ID：10.1038/cdd.2011.59, ISSN：1350-9047, ORCID：45646380, Web of Science ID：WOS:000292634000006
• Characterization of Glucosylceramides in the Polygonaceae, Rumex obtusifolius L. Injurious Weed　　　　　　　　　　　　　　　
  Masayuki Watanabe; Atsuko Miyagi; Minoru Nagano; Maki Kawai-Yamada; Hiroyuki Imai
  BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 巻：75, 号：5, 開始ページ：877, 終了ページ：881, 2011年05月, ［査読有り］
  Rumex obtusifolius L., a member of Polygonaceae, is one of the world's worst weeds. We characterized the glucosylceramide molecular species in leaves of R. obtusifolius by liquid chromatography/tandem mass spectrometry. 4,8-Sphingadienines were principally paired with 2-hydroxy palmitic acids. In contrast, 4-hydroxy-8-sphingenines were chiefly attached to 2-hydroxy fatty acids with 22 to 26 carbon-chain length. A unique characteristic of the 2-hydroxy fatty acid composition of R. obtusifolius was the high content of n-9 monoenoic 2-hydroxy fatty acids with 22 and 24 carbon-chain length. The levels of the Z and E stereoisomers of the 8-unsaturated long-chain bases were reliably distinguished from those in other plant families in ten species of Polygonaceae.
  TAYLOR & FRANCIS LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1271/bbb.100802
  DOI ID：10.1271/bbb.100802, ISSN：0916-8451, eISSN：1347-6947, ORCID：45646381, Web of Science ID：WOS:000291519100010
• Bax inhibitor-1による細胞膜マイクロドメインを介した細胞死抑制機構の解析　　　　　　　　　　　　　　　
  石川 寿樹; 秋 利彦; 柳澤 修一; 内宮 博文; 川合 真紀
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2011, 開始ページ：0404, 終了ページ：0404, 2011年
  Bax inhibitor-1 (BI-1) は高等動植物が共通に持つ小胞体局在の細胞死制御因子であり、様々な環境ストレス下における酸化ストレス誘導性細胞死の抑制に寄与する。シロイヌナズナのBI-1 (AtBI-1) は小胞体においてスフィンゴ脂質代謝酵素と相互作用することから、スフィンゴ脂質がBI-1の作用機構に重要な役割を持つことが示唆されている。スフィンゴ脂質は細胞膜マイクロドメインの主要構成因子であり、その分子組成の変化はマイクロドメイン機能に影響を及ぼすことが予想される。そこでAtBI-1過剰発現イネ培養細胞の細胞膜マイクロドメイン構成成分を解析したところ、スフィンゴ糖脂質の増加とタンパク質プロファイルの変化が見出され、AtBI-1によるスフィンゴ脂質代謝の亢進が細胞膜マイクロドメイン構造に影響を及ぼすことが明らかとなった。さらにショットガンプロテオーム解析により、AtBI-1過剰発現細胞で顕著に減少しているタンパク質として過敏感細胞死関連因子やシグナル伝達複合体形成に関与する因子が同定され、これらを介した細胞死抑制メカニズムがBI-1の下流で機能していることが示唆された。本発表では、同定したマイクロドメイン局在タンパク質のストレス誘導性細胞死における機能について報告し、植物の細胞死制御機構における細胞膜マイクロドメインの役割について議論したい。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2011.0.0404.0
  DOI ID：10.14841/jspp.2011.0.0404.0, CiNii Articles ID：130006997013
• ¹³CO₂および高CO₂によるエゾノギシギシのシュウ酸代謝解析　　　　　　　　　　　　　　　
  宮城 敦子; 川合 真紀; 内宮 博文
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2011, 開始ページ：0657, 終了ページ：0657, 2011年
  タデ科植物であるエゾノギシギシは葉にシュウ酸を高蓄積する多年生草本である。その一方で、そのシュウ酸蓄積機構に関する知見は少ない。当研究室におけるメタボローム解析の結果から、葉のシュウ酸の蓄積量とシュウ酸前駆物質（クエン酸、アスコルビン酸）との間に高い正の相関があること、茎の炭素化合物が葉のシュウ酸合成に影響を及ぼすことが示された（Miyagi et al, Metabolomics, 2010a, b）。そこで、本研究では茎の炭素源が葉のシュウ酸蓄積に及ぼす影響を調べるために¹³CO₂を用いたトレーサー実験を行った。すなわち、¹³CO₂処理した植物における¹³C-シュウ酸とその周辺代謝物の濃度をCE-MSで測定した。その結果¹³C-シュウ酸が葉に高蓄積すること、茎では¹³C-クエン酸等の濃度が減少する一方で新生葉のシュウ酸合成に茎の炭素化合物が使用されることが示された。さらに、高CO₂がシュウ酸等の代謝物に及ぼす影響を調べるため、1000 ppm CO₂および栄養塩処理個体の代謝物解析を行った。その結果、葉では栄養塩処理によって主にアミノ酸の濃度が増加するのに対し、CO₂処理により有機酸が増加した。一方、CO₂と栄養塩を同時に処理した個体にシュウ酸濃度の増加が見られ、バイオマス量が著しく増加した。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2011.0.0657.0
  DOI ID：10.14841/jspp.2011.0.0657.0, CiNii Articles ID：130006995798
• ショットガンプロテオミクスによる植物のストレス誘導性細胞死制御に関わる細胞膜マイクロドメインタンパク質の探索　　　　　　　　　　　　　　　
  石川 寿樹; 秋 利彦; 柳澤 修一; 長野 稔; 内宮 博文; 川合 真紀
  日本プロテオーム学会大会要旨集, 巻：2011, 開始ページ：215, 終了ページ：215, 2011年
  日本プロテオーム学会（日本ヒトプロテオーム機構）, 日本語
  DOI：https://doi.org/10.14889/jhupo.2011.0.215.0
  DOI ID：10.14889/jhupo.2011.0.215.0, CiNii Articles ID：130005454359
• Targeted metabolomics in an intrusive weed, Rumex obtusifolius L., grown under different environmental conditions reveals alterations of organ related metabolite pathway　　　　　　　　　　　　　　　
  Atsuko Miyagi; Kentaro Takahara; Hideyuki Takahashi; Maki Kawai-Yamada; Hirofumi Uchimiya
  METABOLOMICS, 巻：6, 号：4, 開始ページ：497, 終了ページ：510, 2010年12月, ［査読有り］
  This study was intended to analyze the metabolic pathway of Rumex obtusifolius L. (Broad-leaved dock), destructive weeds worldwide, in relation to major environmental factors (light and temperature). It was found that R. obtusifolius can be classified as plants in accumulating major organic acids such as oxalate in leaves and citrate in stems (Miyagi et al., Metabolomics 6:146-155 2010). The organ specific accumulation of certain metabolites was dissected by metabolomics approach in relation to metabolic pathway. Light or dark experiments showed that in the case of the oxalate accumulation, the major or the most dominated pathway was found to be the citrate-isocitrate-oxalate shunt. Furthermore, under the dark and/or low temperature (5A degrees C) leaves showed sustainable growth with normal accumulation of TCA metabolites. Unlike leaves, there was a different pattern of metabolite accumulation in stems. Other metabolites such as amino acids also showed the organ specific alterations under the different ambient environments.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-010-0220-0
  DOI ID：10.1007/s11306-010-0220-0, ISSN：1573-3882, ORCID：45646391, Web of Science ID：WOS:000283944300004
• Ammonium-dependent respiratory increase is dependent on the cytochrome pathway in Arabidopsis thaliana shoots　　　　　　　　　　　　　　　
  Takushi Hachiya; Chihiro K. Watanabe; Carolina Boom; Danny Tholen; Kentaro Takahara; Maki Kawai-Yamada; Hirofumi Uchimiya; Yukifumi Uesono; Ichiro Terashima; Ko Noguchi
  PLANT CELL AND ENVIRONMENT, 巻：33, 号：11, 開始ページ：1888, 終了ページ：1897, 2010年11月, ［査読有り］
  Oxygen uptake rates are increased when concentrated ammonium instead of nitrate is used as sole N source. Several explanations for this increased respiration have been suggested, but the underlying mechanisms are still unclear. To investigate possible factors responsible for this respiratory increase, we measured the O(2) uptake rate, activity and transcript level of respiratory components, and concentration of adenylates using Arabidopsis thaliana shoots grown in media containing various N sources. The O(2) uptake rate was correlated with concentrations of ammonium and ATP in shoots, but not related to the ammonium assimilation. The capacity of the ATP-coupling cytochrome pathway (CP) and its related genes were up-regulated when concentrated ammonium was sole N source, whereas the ATP-uncoupling alternative oxidase did not influence the extent of the respiratory increase. Our results suggest that the ammonium-dependent increase of the O(2) uptake rate can be explained by the up-regulation of the CP, which may be related to the ATP consumption by the plasma-membrane H+-ATPase.
  WILEY-BLACKWELL PUBLISHING, INC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/j.1365-3040.2010.02189.x
  DOI ID：10.1111/j.1365-3040.2010.02189.x, ISSN：0140-7791, ORCID：45646385, Web of Science ID：WOS:000283375200009
• Nicotinate/nicotinamide mononucleotide adenyltransferase-mediated regulation of NAD biosynthesis protects guard cells from reactive oxygen species in ABA-mediated stomatal movement in Arabidopsis　　　　　　　　　　　　　　　
  Shin-nosuke Hashida; Taketo Itami; Hideyuki Takahashi; Kentaro Takahara; Minoru Nagano; Maki Kawai-Yamada; Kazuhiro Shoji; Fumiyuki Goto; Toshihiro Yoshihara; Hirofumi Uchimiya
  JOURNAL OF EXPERIMENTAL BOTANY, 巻：61, 号：13, 開始ページ：3813, 終了ページ：3825, 2010年08月, ［査読有り］
  Nicotinamide adenine dinucleotide (NAD) and its derivative nicotinamide adenine dinucleotide phosphate (NADP) are indispensable co-factors in broad-spectrum metabolic events for the maintenance of cellular homeostasis in all living organisms. In this study, the cellular expression levels of NAD biosynthesis genes in Arabidopsis were investigated. A very high expression of nicotinate/nicotinamide mononucleotide adenyltransferase (NMNAT) was observed in the differentiated stomatal guard cells of the leaf surface. Transcriptional analysis confirmed that several genes in the biosynthesis pathway were also highly expressed in stomatal guard cells. In fact, NAD and NADP metabolisms were investigated during stomatal movement. Importantly, the generation of phytohormone ABA-induced reactive oxygen species, which acts as a signal for stomatal closure, was accompanied by markedly decreased levels of NAD. The ABA-induced oxidative stress caused stomatal cell death in the nmnat mutant. Furthermore, stomata partially lost their ability to close leading to drought susceptibility. The stomata were less responsive to opening cues as well. These results indicate that NAD biosynthesis is involved in protecting guard cells from ABA-induced local oxidative stress via the regulation of NMNAT activity. In this study, it is demonstrated that NMNAT is essential for the maintenance of NAD homeostasis enabling sustainable stomatal movement.
  OXFORD UNIV PRESS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/jxb/erq190
  DOI ID：10.1093/jxb/erq190, ISSN：0022-0957, ORCID：45646389, Web of Science ID：WOS:000280905400028
• Effects of AOX1a Deficiency on Plant Growth, Gene Expression of Respiratory Components and Metabolic Profile Under Low-Nitrogen Stress in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Chihiro K. Watanabe; Takushi Hachiya; Kentaro Takahara; Maki Kawai-Yamada; Hirofumi Uchimiya; Yukifumi Uesono; Ichiro Terashima; Ko Noguchi
  PLANT AND CELL PHYSIOLOGY, 巻：51, 号：5, 開始ページ：810, 終了ページ：822, 2010年05月, ［査読有り］
  Expression of alternative oxidase (AOX) and cyanide (CN)-resistant respiration are often highly enhanced in plants exposed to low-nitrogen (N) stress. Here, we examined the effects of AOX deficiency on plant growth, gene expression of respiratory components and metabolic profiles under low-N stress, using an aox1a knockout transgenic line (aox1a) of Arabidopsis thaliana. We exposed wild-type (WT) and aox1a plants to low-N stress for 7d and analyzed their shoots and roots. In WT plants, the AOX1a mRNA levels and AOX capacity increased in proportion to low-N stress. Expression of the genes of the components for non-phosphorylating pathways and antioxidant enzymes was enhanced, but differences between WT and aox1a plants were small. Metabolome analyses revealed that AOX deficiency altered the levels of certain metabolites, such as sugars and sugar phosphates, in the shoots under low-N stress. However, the carbon (C)/N ratios and carbohydrate levels in aox1a plants were similar to those in the WT under low-N stress. Our results indicated that the N-limited stress induced AOX expression in A. thaliana plants, but the induced AOX may not play essential roles under stress due to low-N alone, and the C/N balance under low-N stress may be tightly regulated by systems other than AOX.
  OXFORD UNIV PRESS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcq033
  DOI ID：10.1093/pcp/pcq033, ISSN：0032-0781, eISSN：1471-9053, ORCID：45646386, Web of Science ID：WOS:000277734900012
• Metabolome and Photochemical Analysis of Rice Plants Overexpressing Arabidopsis NAD Kinase Gene　　　　　　　　　　　　　　　
  Kentaro Takahara; Ichiro Kasajima; Hideyuki Takahashi; Shin-nosuke Hashida; Taketo Itami; Haruko Onodera; Seiichi Toki; Shuichi Yanagisawa; Maki Kawai-Yamada; Hirofumi Uchimiya
  PLANT PHYSIOLOGY, 巻：152, 号：4, 開始ページ：1863, 終了ページ：1873, 2010年04月, ［査読有り］
  The chloroplastic NAD kinase (NADK2) is reported to stimulate carbon and nitrogen assimilation in Arabidopsis (Arabidopsis thaliana), which is vulnerable to high light. Since rice (Oryza sativa) is a monocotyledonous plant that can adapt to high light, we studied the effects of NADK2 expression in rice by developing transgenic rice plants that constitutively expressed the Arabidopsis chloroplastic NADK gene (NK2 lines). NK2 lines showed enhanced activity of NADK and accumulation of the NADP(H) pool, while intermediates of NAD derivatives were unchanged. Comprehensive analysis of the primary metabolites in leaves using capillary electrophoresis mass spectrometry revealed elevated levels of amino acids and several sugar phosphates including ribose-1,5-bisphosphate, but no significant change in the levels of the other metabolites. Studies of chlorophyll fluorescence and gas change analyses demonstrated greater electron transport and CO2 assimilation rates in NK2 lines, compared to those in the control. Analysis of oxidative stress response indicated enhanced tolerance to oxidative stress in these transformants. The results suggest that NADP content plays a critical role in determining the photosynthetic electron transport rate in rice and that its enhancement leads to stimulation of photosynthesis metabolism and tolerance of oxidative damages.
  AMER SOC PLANT BIOLOGISTS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.110.153098
  DOI ID：10.1104/pp.110.153098, ISSN：0032-0889, eISSN：1532-2548, ORCID：45646388, Web of Science ID：WOS:000276335900011
• Principal component and hierarchical clustering analysis of metabolites in destructive weeds; polygonaceous plants　　　　　　　　　　　　　　　
  Atsuko Miyagi; Hideyuki Takahashi; Kentaro Takahara; Takayuki Hirabayashi; Yoshiki Nishimura; Takafumi Tezuka; Maki Kawai-Yamada; Hirofumi Uchimiya
  METABOLOMICS, 巻：6, 号：1, 開始ページ：146, 終了ページ：155, 2010年03月, ［査読有り］
  Comprehensive analysis of metabolites using capillary electrophoresis-mass spectrometry was carried out in harmful weeds belonging to Polygonaceae. A principal component analysis revealed clear distinctions among eight Rumex species and Fallopia japonica. Hierarchical clustering data showed that respective metabolites can be grouped due to species differences. There was a positive relationship between oxalate and citrate, oxalate and ascorbate, and oxalate and glutamine. The amount of oxalate per leaf fresh weight was not affected by increased concentrations of exogenously supplied nutrients from Hoagland's formulation in one of the most destructive weeds R. obtusifolius. The oxalate accumulation in this plant is independent of external nutrient level, where nutrient-rich environments apparently stimulate internal constituents such as amino acids and other metabolites.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-009-0186-y
  DOI ID：10.1007/s11306-009-0186-y, ISSN：1573-3882, ORCID：45646390, Web of Science ID：WOS:000275444800013
• シロイヌナズナの細胞死抑制因子AtBI-1とスフィンゴ脂質脂肪酸代謝との関係　　　　　　　　　　　　　　　
  長野 稔; 角田 智佳子; 内宮 博文; 川合 真紀
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2010, 開始ページ：0545, 終了ページ：0545, 2010年
  植物の形態形成時やストレス応答時に重要な現象であるプログラム細胞死は様々な因子によって高度に制御されている。Bax Inhibitor-1 (BI-1) は生物間に広く保存された細胞死抑制因子である。シロイヌナズナのBI-1 (AtBI-1) は約26kDaの小胞体膜に局在する7回膜貫通タンパク質で、活性酸素種（ROS）の発生を伴う酸化ストレス誘導性細胞死を抑制することがこれまでに報告されている。また、AtBI-1のC末端に存在するcoiled-coil構造が細胞死抑制機能に必須であり、カルモジュリンと相互作用することも明らかとなっている。しかし、これまでAtBI-1が細胞死を抑制する分子機構については明らかとなっていなかった。
  そこで、我々はAtBI-1が電子伝達因子シトクロムb5を介してスフィンゴ脂質脂肪酸代謝酵素と相互作用する可能性を見出した。スフィンゴ脂質は、2-ヒドロキシル化された非常に長い脂肪酸（2-ヒドロキシ超長鎖脂肪酸）を有することが特徴であり、その合成に密接に関与するスフィンゴ脂質脂肪酸2-ヒドロキシラーゼ（AtFAH）及び、超長鎖脂肪酸縮合酵素（AtELO）がAtBI-1と相互作用することが示唆されている。今回の発表では、AtFAH及びAtELOが合成するスフィンゴ脂質脂肪酸とAtBI-1との関係について報告したい。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2010.0.0545.0
  DOI ID：10.14841/jspp.2010.0.0545.0, CiNii Articles ID：130006991529
• Programmed cell death in plants　　　　　　　　　　　　　　　
  Avijit Das; Maki Kawai-Yamada; Hirofumi Uchimiya
  Abiotic Stress Adaptation in Plants: Physiological, Molecular and Genomic Foundation, 開始ページ：371, 終了ページ：383, 2010年, ［査読有り］
  Throughout the life cycle of plants, programmed cell death (PCD) is involved in a wide range of deve-lopmental processes and responses against abiotic or biotic stresses. PCD is an active form of cellular suicide controlled by a network of genes. Such phenomenon is associated with recovery of cellular compounds and sustaining plant life. Basic morphological and biochemical features of PCD are believed to be conserved in both plants and animals. Nevertheless, recent studies demonstrate an involvement of organelles such as vacuole and chloroplast in plant cell death regulation, indicating that plants evolved own cell death machinery. Reactive oxygen species (ROS) generated by biotic and abiotic stresses act as a signal that induces plant PCD. This article describes some of the fundamental characteristics of plant PCD and raises points that may lead to a better understanding and novel strategies for plant molecular breeding. © 2010 Springer Science + Business Media B.V. All Rights Reserved.
  Springer Netherlands, 英語, 論文集(書籍)内論文
  DOI：https://doi.org/10.1007/978-90-481-3112-9_17
  DOI ID：10.1007/978-90-481-3112-9_17, SCOPUS ID：84856505544
• Metabolome Analysis of Response to Oxidative Stress in Rice Suspension Cells Overexpressing Cell Death Suppressor Bax Inhibitor-1　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Kentaro Takahara; Takayuki Hirabayashi; Hideo Matsumura; Shizuko Fujisawa; Ryohei Terauchi; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANT AND CELL PHYSIOLOGY, 巻：51, 号：1, 開始ページ：9, 終了ページ：20, 2010年01月, ［査読有り］
  Bax inhibitor-1 (BI-1) is a cell death suppression factor widely conserved in higher plants and animals. Overexpression of Arabidopsis BI-1 (AtBI-1) in plants confers tolerance to various cell death-inducible stresses. However, apart from the cell death-suppressing activity, little is known about the physiological roles of BI-1-overexpressing plants. In this study, we evaluated the effects of AtBI-1 overexpression on the rice metabolome in response to oxidative stress. AtBI-1-overexpressing rice cells in suspension displayed enhanced tolerance to menadione-induced oxidative stress compared with vector control cells, whereas AtBI-1 overexpression did not influence the increase of intracellular H2O2 concentration or inhibition of oxidative stress-sensitive aconitase activity. Capillary electrophoresismass spectrometry (CE-MS)-based metabolome analysis revealed dynamic metabolic changes in oxidatively stressed rice cells, e.g. depletion of the central metabolic pathway, imbalance of the redox state and energy charge, and accumulation of amino acids. Furthermore, comparative metabolome analysis demonstrated that AtBI-1 overexpression did not affect primary metabolism in rice cells under normal growth conditions but significantly altered metabolite composition within several distinct pathways under cell death-inducible oxidative stress. The AtBI-1-mediated metabolic alteration included recovery of the redox state and energy charge, which are known as important factors for metabolic defense against oxidative stress. These observations suggest that although AtBI-1 does not affect rice metabolism directly, its cell death suppression activity leads to enhanced capacity to acclimate oxidative stress.
  OXFORD UNIV PRESS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcp162
  DOI ID：10.1093/pcp/pcp162, ISSN：0032-0781, eISSN：1471-9053, ORCID：45646387, Web of Science ID：WOS:000273704500002
• SMAP2 protein potentially medicates the response to synthetic auxin, 2,4-D, in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Akari Nakasone; Maki Kawai-Yamada; Tomohiro Kiyosue; Issay Narumi; Hirofumi Uchimiya; Yutaka Oono
  JAEA Takasaki Annual Report 2008, 開始ページ：65, 2009年12月
• A gene encoding SMALL ACIDIC PROTEIN 2 potentially mediates the response to synthetic auxin, 2,4-dichlorophenoxyacetic acid, in Arabidopsis thaliana.　　　　　　　　　　　　　　　
  Akari Nakasone; Maki Kawai-Yamada; Tomohiro Kiyosue; Issay Narumi; Hirofumi Uchimiya; Yutaka Oono
  Journal of plant physiology, 巻：166, 号：12, 開始ページ：1307, 終了ページ：13, 2009年08月, ［査読有り］, ［国際誌］
  The SMALL ACIDIC PROTEIN 2 (SMAP2) gene is a paralogue of the SMAP1 gene that mediates the response to the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) in the root of Arabidopsis thaliana. Their encoded proteins, SMAP1 and SMAP2, are similar in calculated molecular weight and isoelectric point, and in having a highly conserved phenylalanine and aspartic acid-rich domain. RNA expression analysis showed that SMAP1 mRNA is present throughout the plant body while SMAP2 mRNA is restricted to siliques and anthers. Over-expression of the SMAP2 gene, as well as SMAP1, by 35S cauliflower mosaic virus promoter restored sensitivity to 2,4-D in the 2,4-D-resistant mutant, aar1, which is defective in SMAP1 function. The results suggest that SMAP2 has an ability to mediate the 2,4-D response and is expressed only in restricted tissues.
  英語
  DOI：https://doi.org/10.1016/j.jplph.2009.02.005
  DOI ID：10.1016/j.jplph.2009.02.005, ORCID：45646392, PubMed ID：19307045, Web of Science ID：WOS:000268818200008
• 強害帰化雑草エゾノギシギシのメタボローム解析　　　　　　　　　　　　　　　
  宮城 敦子; 平林 孝之; 高橋 秀行; 西村 芳樹; 高原 健太郎; 川合 真紀; 内宮 博文
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2009, 開始ページ：0315, 終了ページ：0315, 2009年
  タデ科ギシギシ属エゾノギシギシRumex obtusifolius L.は世界各地の田畑や牧草地などに多く見られる多年生草本であり、駆除が困難な強害雑草として知られている。日本では、明治期に北海道にて移入が確認された後、数十年の間にほぼ全国に分布を拡大し、特に問題視されている。
  タデ科ギシギシ属の植物は、シュウ酸含有量が高い。シュウ酸の過剰摂取は動物にとって有害である一方で、植物においてシュウ酸は重要な役割を果たしていると考えられる。というのは、シュウ酸は防御分子である過酸化水素合成の基質の1つであるため、傷害などのストレス応答との関与が推測されている。また、シュウ酸を根圏へ放出することで土壌中の金属イオンとキレートを形成し、金属イオンの毒性を打ち消すという報告がある。
  本研究ではエゾノギシギシのシュウ酸代謝を明らかにするため、CE-MSを用いてギシギシ属植物の葉の代謝物量を測定し種間比較を行った。その結果、エゾノギシギシは他種よりもシュウ酸を高蓄積した。また、シュウ酸を高蓄積する植物ほどアミノ酸を多く含む傾向が見られた。さらに、地上部を切除し暗条件で育成したエゾノギシギシの葉および茎のメタボローム解析を行った。その結果、暗条件では茎の主要代謝物であるクエン酸が葉のシュウ酸の高蓄積に関与する可能性が示された。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2009.0.0315.0
  DOI ID：10.14841/jspp.2009.0.0315.0, CiNii Articles ID：130006994320
• NAD生合成酵素NMNATによる気孔閉鎖運動の制御　　　　　　　　　　　　　　　
  橋田 慎之介; 高橋 秀行; 高原 健太郎; 長野 稔; 川合 真紀; 内宮 博文
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2009, 開始ページ：0325, 終了ページ：0325, 2009年
  ニコチンアミド補酵素群（NAD(P)(H)）はエネルギー伝達など細胞機能に不可欠な因子であり極めて重要な役割を担っているが、その生合成制御についての知見は乏しい。シロイヌナズナにおいてNADはde novo経路とsalvage経路から合成される。NaMN合成後に2つの経路は合流し、共通経路においてNaADへ変換された後にNADが合成される。これまでに我々のグループでは、共通経路を触媒するNMNATおよびNADS遺伝子を同定し、さらに転写解析およびプロモーターGUS解析によってNADが生合成される組織・細胞を同定してきた。本講演では孔辺細胞におけるNAD生合成について報告する。シロイヌナズナ表皮ではアブシジン酸に応答して一過的にNADレベルが減少し、遅れてNMNAT活性が上昇することを見出した。このときNMNATの転写レベルは変化しなかった。また、NADSは転写・酵素活性共に変化しなかった。以上の結果から、NADレベルはNMNAT活性によって一定に保たれると推測された。孔辺細胞プロトプラストを用いた実験結果から、この応答は孔辺細胞特異的であることが明らかとなった。NMNAT変異体では気孔閉鎖が制限され乾燥耐性が低下するのに対して、NMNAT過剰発現体では気孔閉鎖が促進され乾燥耐性が付与されることを確認した。以上の結果から、NAD生合成と気孔運動との関連が示唆された。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2009.0.0325.0
  DOI ID：10.14841/jspp.2009.0.0325.0, CiNii Articles ID：130006994190
• エネルギー代謝補酵素による植物代謝亢進　　　　　　　　　　　　　　　
  高橋 秀行; 高原 健太郎; 橋田 慎之介; 川合 真紀
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2009, 開始ページ：0174, 終了ページ：0174, 2009年
  エネルギー代謝補酵素（NAD(P)(H)）は、生体内で数百に及ぶ酸化還元反応を触媒する脱水素酵素の補酵素である。従来、これらの補酵素は細胞内レドックスの調節因子と考えられてきたが、近年の研究から、補酵素自体の量も重要であることがわかってきている。NAD(P)(H)の合成経路には、NAD合成酵素、ニコチンアミドモノヌクレオチドアデニルトランスフェラーゼ、NADリン酸化酵素（NADK）の3種類の鍵酵素が存在し、主にこれらの酵素群によって量的変動が制御されていると考えられる。本研究では、NAD(P)(H)量の変動による植物代謝への影響を見出し、NAD(P)(H)による代謝調節機構を明らかにする。
  NAD代謝を改変したシロイヌナズナ形質転換体を代謝解析した結果、NADP量の減少によって光合成が阻害された。さらにNAD(P(H)を変動させることで代謝の変動を示唆する結果も得られたことから、NAD(P)(H)は植物代謝の調節因子であることが予想された。今後の解析から、個々の補酵素の代謝調節因子としての働きが明らかになると考えられる。NAD(P)(H)を利用した代謝改変技術が確立すれば、植物の能力や品質向上を目的としたデザイン育種の新たな戦略として、応用が期待できる。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2009.0.0174.0
  DOI ID：10.14841/jspp.2009.0.0174.0, CiNii Articles ID：130006991067
• シロイヌナズナにおけるスフィンゴ脂質脂肪酸ヒドロキシラーゼの役割　　　　　　　　　　　　　　　
  長野 稔; 内宮 博文; 川合 真紀
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2009, 開始ページ：0216, 終了ページ：0216, 2009年
  スフィンゴ脂質は真核生物の膜を構成する脂質であり、シグナル伝達、タンパク質輸送、プログラム細胞死など様々な細胞内反応で重要な働きをすることが知られている。スフィンゴ脂質は、糖やリン酸などの頭部と、長鎖塩基及び脂肪酸からなるセラミド部位から構成され、その特徴の一つとして2-ヒドロキシル化された脂肪酸（2-ヒドロキシ脂肪酸）を有することが挙げられる。2-ヒドロキシ脂肪酸の形成はスフィンゴ脂質脂肪酸ヒドロキシラーゼ、fatty acid hydroxylase (FAH) が担うことがこれまでに明らかとなっている。シロイヌナズナにはFAHは2つ存在し（AtFAH1, AtFAH2）、ともに小胞体膜に局在する。出芽酵母を用いた解析から、シトクロムb5と相互作用することでヒドロキシラーゼ活性を増大させることが明らかとなった。さらに、シロイヌナズナにおいて、AtFAH1はC22以上の脂肪酸を、AtFAH2はC16の脂肪酸を主に基質とするヒドロキシラーゼであることを見出した。また、シロイヌナズナのAtFAH1のノックダウン系統及びT-DNA挿入変異体を用いた解析から、2-ヒドロキシ脂肪酸が酸化ストレス耐性に関与することが明らかとなった。今回の発表では、シロイヌナズナにおいてAtFAHsが担う役割について報告する。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2009.0.0216.0
  DOI ID：10.14841/jspp.2009.0.0216.0, CiNii Articles ID：130006991164
• NAD関連遺伝子によるC-N代謝促進　　　　　　　　　　　　　　　
  高橋 秀行; 橋田 慎之介; 藤森 玉輝; 川合(山田) 真紀; 田茂井 政宏; 重岡 成; 柳澤 修一; 内宮 博文
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2008, 開始ページ：0297, 終了ページ：0297, 2008年
  葉緑体局在型NADK（NADK2）はPSIIの電子伝達とキサントフィルサイクルを正常に働かせるために必須の酵素である。代謝解析の結果、NADK2高発現体ではカルビン回路の代謝物が増加することが明らかになった。さらにカルビン回路の酵素であるRubisCO及びグリセルアルデヒド3リン酸脱水素酵素の活性化と二酸化炭素取り込み量の増加が観察されたことから、炭素固定能の上昇が示された。一方、本植物体ではグルタミン酸を中心とした遊離アミノ酸が増加し、さらに低窒素条件で生育が著しく悪化することから、窒素代謝への影響が示唆された。それらを明らかにするため、窒素代謝に関わる酵素の発現および活性、イオンについて調査した。高発現体では葉緑体局在型グルタミン合成酵素（GS2）とNADH依存性グルタミン酸合成酵素（GOGAT）の発現が上昇しており、GS/GOGAT経路が発現レベルで上昇していることが明らかになった。ここで、GS/GOGAT経路におけるアミノ酸合成には、硝酸の取り込みと還元による窒素源の供給が必須である。高発現体では硝酸取り込みの上昇と硝酸還元酵素の活性化が観察された。これらの結果から、NADK2の高発現によって硝酸還元活性が上昇し、同時に活性化したGS/GOGATによってアミノ酸合成が促進されていることが推測された。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2008.0.0297.0
  DOI ID：10.14841/jspp.2008.0.0297.0, CiNii Articles ID：130006994378
• スフィンゴ脂質関連酵素を介したAtBI-1による植物細胞死抑制機構の解析　　　　　　　　　　　　　　　
  長野 稔; 井原(大堀) 由理; 角田 智佳子; 内宮 博文; 川合 真紀
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2008, 開始ページ：0279, 終了ページ：0279, 2008年
  植物において、プログラム細胞死は様々な因子によって高度に制御されている。Bax Inhibitor-1 (BI-1) は生物間に広く保存された細胞死抑制因子である。シロイヌナズナのBI-1 (AtBI-1) は約26kDaの小胞体膜に局在する7回膜貫通タンパク質で、植物細胞に過剰発現させると、過酸化水素、サリチル酸、エリシターなどによって引き起こされる細胞死を抑制することがこれまでに報告されている。また、AtBI-1のC末端に存在するcoiled-coil構造が細胞死抑制機能に必須であり、カルモジュリンと相互作用することも明らかとなっている。しかし、これまでAtBI-1が細胞死を抑制する分子機構については明らかとなっていなかった。
  最近の我々の研究から、AtBI-1がAtFAH (Arabidopsis fatty acid hydroxylase) とcytochrome b₅ (Cb5) を介して相互作用することが示唆された。Cb5は脂肪酸合成に関与する電子伝達因子で、AtFAHはスフィンゴ脂質脂肪酸のヒドロキシラーゼであり、小胞体に局在している。近年、セラミドを含むスフィンゴ脂質が細胞死制御に関与することが明らかになりつつある。本研究は、AtBI-1がスフィンゴ脂質制御を介して細胞死の抑制を行っていることを示唆している。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2008.0.0279.0
  DOI ID：10.14841/jspp.2008.0.0279.0, CiNii Articles ID：130006993957
• ニコチンアミド補酵素生合成変異体における花粉休眠性の低下　　　　　　　　　　　　　　　
  橋田 慎之介; 高原 健太郎; 高橋 秀行; 川合 真紀; 内宮 博文
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2008, 開始ページ：0238, 終了ページ：0238, 2008年
  多くの顕花植物では、水分含量の低下に伴い代謝活性が低下した休眠状態で花粉は放出される。休眠状態の花粉は低湿度条件下で長期生存（保存）可能であり、顕花植物における自然交雑の成否は花粉寿命によって決定される場合が多い。近年、シロイヌナズナにおいて花粉休眠変異体が多数同定されたが、その分子機構は未だ明らかになっていない。我々のグループではシロイヌナズナを実験材料に用いて、ニコチンアミド補酵素群生合成の鍵酵素であるニコチン酸／ニコチンアミドモノヌクレオチドアデニル基転移酵素（NMNAT）遺伝子の欠損花粉（nmnat花粉）では野生型と比較して花粉寿命が低下する事を見出した。蛍光試薬を用いたトレーサー実験によって、葯裂開直後のnmnat花粉からは残留水分が検出され、花粉発達過程最終段階における脱水反応が不十分であることが明らかとなった。変異体を高湿度条件下で育成した場合、nmnat花粉特異的に葯室内部での花粉発芽および花粉管伸長が検出された。以上の結果は花粉が乾燥耐性を獲得して休眠状態へ移行するにはNAD生合成が必須である事を示す。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2008.0.0238.0
  DOI ID：10.14841/jspp.2008.0.0238.0, CiNii Articles ID：130006993793
• Identification of novel mitochondrial membrane protein (Cdf 3) from Arabidopsis thaliana and its functional analysis in a yeast system　　　　　　　　　　　　　　　
  Kyung-Min Kim; Do-Youn Jun; Sang-Kook Kim; Chang-Kil Kim; Byung Oh Kim; Young-Ho Kim; Wan Park; Jae-Keun Sohn; Aiko Hirata; Maki Kawai-Yamada; Hirofumi Uchimiya; Dai-Hee Kim; Ill-Whan Sul
  JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY, 巻：17, 号：6, 開始ページ：891, 終了ページ：896, 2007年06月, ［査読有り］
  We screened the Arabidopsis cDNA library to identify functional suppressors of AtBI-1, a gene that suppresses cell death induced by Bax gene expression in yeast. Cdf 3 encodes a 118-amino-acid protein with a molecular mass of 25 kDa. This protein has two uncharacterized domains at amino acids residues 5-64 and 74-117. In the present study, CDF3 was found to induce growth defects in yeast and arrested yeast growth, although the cell-growth defect was somewhat less than that of Bax. Its localization in the inner mitochondria was essential for suppression of yeast-cell proliferation. The morphological abnormality of the intracellular network, which is a hallmark of AtBI-1, was attenuated by Cdf 3 expression.
  KOREAN SOC MICROBIOLOGY & BIOTECHNOLOGY, 英語, 研究論文（学術雑誌）
  ISSN：1017-7825, eISSN：1738-8872, Web of Science ID：WOS:000247703500002
• Young Investigator Award - Plant cell death as an oxidative stress response　　　　　　　　　　　　　　　
  Maki Kawai-Yamada
  PLANT AND CELL PHYSIOLOGY, 巻：48, 開始ページ：S16, 終了ページ：S16, 2007年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  DOI：https://doi.org/10.14841/jspp.2007.0.A002.0
  DOI ID：10.14841/jspp.2007.0.A002.0, ISSN：0032-0781, ORCID：45646410, Web of Science ID：WOS:000245922700060
• Mechanism of metabolic activation through altered NAD metabolism
  Maki Kawai-Yamada; Hideyuki Takahashi; Shin-Nosuke Hashida; Hirofumi Uchimiya
  PLANT AND CELL PHYSIOLOGY, 巻：48, 開始ページ：S9, 終了ページ：S9, 2007年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  ISSN：0032-0781, ORCID：45646407, Web of Science ID：WOS:000245922700036
• Functional analysis of Arabidopsis thaliana NAD biosynthetic genes　　　　　　　　　　　　　　　
  Shin-nosuke Hashida; Taketo Itami; Hideyuki Takahashi; Maki Kawai-Yamada; Hirofumi Uchimiya
  PLANT AND CELL PHYSIOLOGY, 巻：48, 開始ページ：S42, 終了ページ：S42, 2007年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  DOI：https://doi.org/10.14841/jspp.2007.0.104.0
  DOI ID：10.14841/jspp.2007.0.104.0, ISSN：0032-0781, ORCID：45646406, Web of Science ID：WOS:000245922700166
• The mitochondrial fission regulator DRP3B does not regulate cell death in plants　　　　　　　　　　　　　　　
  Keiko Yoshinaga; Masaru Fujimoto; Shin-Ichi Arimura; Nobuhiro Tsutsumi; Hirofumi Uchimiya; Maki Kawai-Yamada
  Handbook of Environmental Chemistry, Volume 5: Water Pollution, 巻：97, 号：6, 開始ページ：1145, 終了ページ：1149, 2006年06月, ［査読有り］
  Background and Aims: Recent reports have described dramatic alterations in mitochondrial morphology during metazoan apoptosis. A dynamin-related protein (DRP) associated with mitochondrial outer membrane fission is known to be involved in the regulation of apoptosis. This study analysed the relationship between mitochondrial fission and regulation of plant cell death. Methods: Transgenic plants were generated possessing Arabidopsis DRP3B (K56A), the dominant-negative form of Arabidopsis DRP, mitochondrial-targeted green fluorescent protein and mouse Bax. Key Results: Arabidopsis plants over-expressing DRP3B (K56A) exhibited long tubular mitochondria. In these plants, mitochondria appeared as a string-of-beads during cell death. This indicates that DRP3B (K56A) prevented mitochondrial fission during plant cell death. However, in contrast to results for mammalian cells and yeast, Bax-induced cell death was not inhibited in DRP3B (K56A)-expressing plant cells. Similarly, hydrogen peroxide-, menadione-, darkness- and salicylic acid-induced cell death was not inhibited by DRP3B (K56A) expression. Conclusions: These results indicate that the systems controlling cell death in animals and plants are not common in terms of mitochondrial fission. © The Author 2006. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/aob/mcl057
  DOI ID：10.1093/aob/mcl057, ISSN：1433-6863, SCOPUS ID：33947317551
• Analysis of the Arabidopsis thaliana cell growth defect factor 2 (Cdf2) suppressing yeast cell proliferation　　　　　　　　　　　　　　　
  Kyung-Min Kim; Yong Suk Lim; Ill Whan Sul; Aiko Hirata; Maki Kawai-Yamada; Hirofumi Uchimiya
  KOREAN JOURNAL OF GENETICS, 巻：28, 号：2, 開始ページ：201, 終了ページ：206, 2006年06月, ［査読有り］
  The Cdf2 gene, which is a gene reported to suppress the cell death induced by Bax gene expression in yeast, was screened from an Arabidopsis cDNA library using the yeast screening system harboring GAL1 fused to AtBI-1. Cdf2 encodes a protein consisting of 118 amino acid residues with a molecular weight of 28.8 kDa. The protein has one transmembrane domain in the middle of the amino acid sequence (29-106). Cdf2 induces a growth defect in yeast. The Cdf2-GFP fusion protein was localized in the vacuole of Cdf2 expression attenuated the morphological abnormality of the intracellular network, which is a hallmark of AtBI-1.
  GENETICS SOC KOREA, 英語, 研究論文（学術雑誌）
  ISSN：0254-5934, Web of Science ID：WOS:000239182700014
• NMNAT, a key enzyme in NAD biosynthesis, required for normal pollen tube elongation in Arabidopsis　　　　　　　　　　　　　　　
  SN Hashida; H Takahashi; M Kawai-Yamada; H Uchimiya
  PLANT AND CELL PHYSIOLOGY, 巻：47, 開始ページ：S148, 終了ページ：S148, 2006年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  DOI：https://doi.org/10.14841/jspp.2006.0.495.0
  DOI ID：10.14841/jspp.2006.0.495.0, ISSN：0032-0781, ORCID：45646417, Web of Science ID：WOS:000236401401077
• Metabolome analysis of rice cells treated with the cell wall extracts of Magnaporthe grisea
  H Takahashi; H Matsumura; M Kawai-Yamada; H Uchimiya
  PLANT AND CELL PHYSIOLOGY, 巻：47, 開始ページ：S83, 終了ページ：S83, 2006年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  ISSN：0032-0781, ORCID：45646416, Web of Science ID：WOS:000236401400329
• Metabolic studies of oxalate rich plants
  A Miyagi; H Takahashi; M Kawai-Yamada; H Uchimiya
  PLANT AND CELL PHYSIOLOGY, 巻：47, 開始ページ：S60, 終了ページ：S60, 2006年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  ISSN：0032-0781, ORCID：45646415, Web of Science ID：WOS:000236401400240
• Analysis of proteins interacting with cell death suppressor (AtBI-1)
  M Nagano; Y Ihara-Ohori; K Yoshinaga; H Uchimiya; M Kawai-Yamada
  PLANT AND CELL PHYSIOLOGY, 巻：47, 開始ページ：S43, 終了ページ：S43, 2006年, ［査読有り］
  OXFORD UNIV PRESS, 英語
  ISSN：0032-0781, ORCID：45646412, Web of Science ID：WOS:000236401400171
• The rice metallothionein gene promoter does not direct foreign gene expression in seed endosperm　　　　　　　　　　　　　　　
  H Fukuzawa; LH Yu; C Umeda-Hara; M Tagawa; H Uchimiya
  PLANT CELL REPORTS, 巻：23, 号：4, 開始ページ：231, 終了ページ：235, 2004年10月, ［査読有り］
  We generated transgenic tobacco and rice plants harboring a chimeric gene consisting of the 5'-upstream sequence of the rice metallothionein gene (ricMT) fused to the beta-glucuronidase (GUS) gene. The activity and tissue-specific expression of the ricMT promoter were demonstrated in these transgenic plants. In the transgenic rice plants, despite substantial levels of GUS activity in the shoot and root, almost no GUS signal was detected in the endosperm. Thus, the ricMT promoter could be useful in avoiding accumulation of undesired proteins in the seed endosperm.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00299-004-0813-z
  DOI ID：10.1007/s00299-004-0813-z, ISSN：0721-7714, Web of Science ID：WOS:000224614500008
• Isolation of a cotton CAP gene: a homologue of adenylyl cyclase-associated protein highly expressed during fiber elongation
  M Kawai; S Aotsuka; H Uchimiya
  PLANT AND CELL PHYSIOLOGY, 巻：39, 号：12, 開始ページ：1380, 終了ページ：1383, 1998年12月, ［査読有り］
  The cDNA encoding CAP (adenylyl cyclase-associated protein) was isolated from a cotton (Gossypium hirsutum) fiber cDNA library. The cDNA (GhCAP) contained an open reading frame that encoded 471 amino acid residues. RNA blot analysis showed that the cotton CAP gene was expressed mainly in young fibers.
  JAPANESE SOC PLANT PHYSIOLOGISTS, 英語, 研究論文（学術雑誌）
  ISSN：0032-0781, ORCID：45646432, Web of Science ID：WOS:000077761600019
• イネの根における細胞の生と死の転換機構の解析
  内宮博文; 川合真紀; 梅田(原)千景; 梅田正明
  育種学雑誌, 巻：48, 開始ページ：32, 1998年04月
  日本語
  ISSN：0536-3683, J-Global ID：200902180414092543
• 植物におけるプログラムされた細胞死 細胞死による通気組織形成の機構
  川合真紀; 梅田正明; 内宮博文
  月刊組織培養, 巻：22, 号：1, 開始ページ：8, 終了ページ：12, 1996年01月
  日本語
  ISSN：0386-1791, J-Global ID：200902141757145191
• TISSUE-SPECIFIC LOCALIZATION OF ADENYLATE KINASE IN RICE (ORYZA-SATIVA L) PLANTS
  M KAWAI; H UCHIMIYA
  JOURNAL OF PLANT PHYSIOLOGY, 巻：146, 号：3, 開始ページ：239, 終了ページ：242, 1995年06月, ［査読有り］
  Anti-adenylate kinase (AK) antibody was used to locate AK protein in organs and tissues of rice plants. This antibody reacted with a 27-kDa protein in callus, root, and leaf tissues. Tissue-printing immunoblot analysis revealed that AK proteins were expressed intensively in vascular tissues.
  GUSTAV FISCHER VERLAG, 英語, 研究論文（学術雑誌）
  ISSN：0176-1617, ORCID：45646436, Web of Science ID：WOS:A1995RJ37600008
• イネ アデニレートキナーゼ(AK)遺伝子の構造とストレス応答
  川合真紀; 梅田正明; 内宮博文
  育種学雑誌, 巻：44, 開始ページ：253, 1994年
  日本語
  ISSN：0536-3683, J-Global ID：200902144795110961
• イネヌクレオチドキナーゼ(AK,NDK)遺伝子の構造と遺伝子発現
  川合真紀; 矢野明; 梅田正明; 内宮博文
  Jpn J Breed, 巻：43, 開始ページ：39, 1993年
  日本語
  ISSN：0536-3683, J-Global ID：200902124807785403
• MOLECULAR CHARACTERIZATION OF CDNA-ENCODING FOR ADENYLATE KINASE OF RICE (ORYZA-SATIVA L)　　　　　　　　　　　　　　　
  M KAWAI; S KIDOU; A KATO; H UCHIMIYA
  PLANT JOURNAL, 巻：2, 号：6, 開始ページ：845, 終了ページ：854, 1992年11月, ［査読有り］
  Two types of genes (Adk-a, and Adk-b) encoding for adenylate kinase (AK, EC 2.7.4.3.) were isolated from the cDNA library constructed from poly(A)+ RNA of rice (Oryza sativa L.). Two cDNAs were heterogeneous at 5' and 3' ends of non-coding sequences and had possible polyadenylation signals. One of the genes, Adk-a, had 1154 bp sequences encoding 241 amino acid residues, while the other type, Adk-b, contained 1085 bp sequences encoding for 243 amino acid residues. Homology between Adk-a and Adk-b was 73.7% in nucleotide sequences, and 90.8% in amino acid level. Two genes showed about 53% homology to bovine mitochondrial adenylate kinase (AK2) at nucleotide and amino acid levels. Concerning the codon usage of rice AK genes, T was abundant at the third position of a codon in the reading frames.
  In order to examine the enzyme activity of the protein encoded by the rice cDNA, Adk-a was cloned into an expression vector, pUC119, which was introduced into Escherichia coli strain CV2, a temperature-sensitive mutant of adenylate kinase. We found that the transformant carrying the rice Adk-a gene in the sense orientation recovered cell growth at non-permissive high temperature (42-degrees-C) and expressed enzyme activities higher than the untransformed CV2 and the transformant possessing Adk-a cDNA in the antisense orientation. These observations suggest that rice Adk-a codes a biologically active enzyme. Furthermore, sucrose was found to regulate the transcription of AK genes in rice cell cultures. Organ related accumulation of mRNA in whole plants was also found.
  BLACKWELL SCIENCE LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1046/j.1365-313X.1992.t01-1-00999.x
  DOI ID：10.1046/j.1365-313X.1992.t01-1-00999.x, ISSN：0960-7412, ORCID：45646437, Web of Science ID：WOS:A1992JY25100002

• 植物のクチクラ形成を調節する乾燥応答ネットワークの解析　　　　　　　　　　　　　　　
  浦野薫; 圓山恭之進; 大島良美; 大島良美; 坂本真吾; 石川寿樹; 川合真紀; 佐藤繭子; 豊岡公徳; 篠崎和子; 篠崎和子; 篠崎一雄
  日本植物生理学会年会(Web), 巻：62nd, 2021年
  J-Global ID：202102212550428101
• イネ品種間におけるシュウ酸蓄積の比較解析　　　　　　　　　　　　　　　
  宮城敦子; 安達俊輔; 大川泰一郎; 川合真紀
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：37th, 開始ページ：68, 2019年08月25日
  日本語
  J-Global ID：201902223570072576
• 光合成誘導反応のイネ品種間差に関わる生理的要因の解析　　　　　　　　　　　　　　　
  安達俊輔; 田中佑; 宮城敦子; 鹿島誠; 手塚あゆみ; 戸谷吉博; 小林俊造; 大久保智司; 清水浩; 川合真紀; 永野惇; 矢守航
  日本作物学会講演会要旨集, 巻：247th, 開始ページ：65, 2019年03月28日
  日本語
  J-Global ID：201902277546415649
• 光合成における電子受容体NADP⁺供給システムと電子伝達の交互作用　　　　　　　　　　　　　　　
  橋田慎之介; 川合真紀
  日本植物生理学会年会(Web), 巻：60th, 2019年
  J-Global ID：201902254199254282
• シロイヌナズナVND遺伝子群の遺伝学的解析
  伊藤敦也; 久保稔; 大谷美沙都; 石川寿樹; 川合真紀; 出村拓; 山口雅利
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：36th, 開始ページ：153, 2018年08月15日
  日本語
  J-Global ID：201802264094945466
• イネにおける染色体部分置換がシュウ酸蓄積に及ぼす影響
  宮城敦子; 安達俊輔; 野口航; 常田岳志; 臼井靖浩; 中村浩史; 酒井英光; 長谷川利拡; 山本敏夫; 大川泰一郎; 川合真紀
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：36th, 開始ページ：115, 2018年08月15日
  日本語
  J-Global ID：201802258186947949
• イオンビーム照射イネ系統におけるメタボローム解析
  宮城敦子; 西丸拓也; 大野豊; 長谷純宏; 川合真紀
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：34th, 開始ページ：77, 2016年08月20日
  日本語
  J-Global ID：201602249993963032
• イオンビームを照射した高シュウ酸植物エゾノギシギシの代謝解析
  宮城敦子; 北野沙也佳; 長谷純宏; 大野豊; 山口雅利; 川合真紀
  日本植物学会大会研究発表記録, 巻：79th, 開始ページ：134, 2015年09月01日
  日本語
  J-Global ID：201502214850620962
• NAD(P)代謝改変シロイヌナズナの作出および代謝解析　　　　　　　　　　　　　　　
  鈴木渉太; 宮城敦子; 石川寿樹; 刑部敬史; 長野稔; 山口雅利; 川合真紀
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：33rd, 開始ページ：140, 2015年07月20日
  日本語
  J-Global ID：201502202919376033
• Metabolome analysis of leaves of Rumex obtusifolius L. irradiated with ion beams.　　　　　　　　　　　　　　　
  Atsuko Miyagi; Sayaka Kitano; Yutaka Oono; Yoshihiro Hase; Maki Kawai-Yamada
  JAEA Review 2014-050, 開始ページ：114, 2015年03月
  日本語
• 放射線照射高シュウ酸植物のメタボローム解析
  宮城敦子; 北野沙也佳; 大野豊; 長谷純宏; 川合真紀
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：32nd, 開始ページ：100, 2014年07月30日
  日本語
  J-Global ID：201402237207551572
• Effects of gamma-ray irradiation on oxalate Metabolism in Rumex obtusifolius L.　　　　　　　　　　　　　　　
  Sayaka Kitano; Atsuko Miyagi; Yutaka Ohno; Yoshihiro Hase; Issay Narumi; Hirofumi Uchimiya; Maki Kawai-Yamada
  JAEA-Review, 巻：2013-059, 開始ページ：108, 2014年03月
• 植物のアルミニウムストレスと代謝物解析
  宮城 敦子; 川合真紀; 内宮博文
  農業および園芸, 巻：89, 号：1, 開始ページ：34, 終了ページ：39, 2014年01月01日
  日本語, 記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）
  ISSN：0369-5247, J-Global ID：201402268976322988
• ガンマ線が高シュウ酸植物の代謝に及ぼす影響
  北野沙也佳; 宮城敦子; 大野豊; 長谷純弘; 鳴海一成; 山口雅利; 内宮博文; 川合真紀
  日本植物学会大会研究発表記録, 巻：77th, 開始ページ：185, 2013年08月20日
  日本語
  J-Global ID：201302255221317192
• 雑草のメタボローム研究〔3〕—エゾノギシギシの二酸化炭素応答—　　　　　　　　　　　　　　　
  宮城敦子; 川合真紀; 内宮博文
  農業および園芸, 巻：87, 号：7, 開始ページ：694-700, 2012年07月
  日本語
  ISSN：0369-5247, J-Global ID：201202276171386520
• Theories in PAM chlorophyll fluorescence measurement of plant leaves　　　　　　　　　　　　　　　
  Ichiro Kasajima; Maki Kawai-Yamada; Maki Kawai-Yamada; Hirofumi Uchimiya; Hirofumi Uchimiya
  Photochemistry: UV/VIS Spectroscopy, Photochemical Reactions and Photosynthesis, 開始ページ：351, 終了ページ：371, 2011年12月01日
  Chlorophyll in chloroplasts is the light-harvesting pigment of plant leaves. Chlorophyll is excited by light energy to reach excitation state. This excitation energy is de-excited by several processes in planta. Of the two photochemical apparatus of photosynthetic electron transport (photosystem I and photosystem II), rate constants of photochemical reactions around photosystem II can be measured with chlorophyll fluorescence, because it is mainly emitted from photosystem II. Fluorescence itself is one of the de-excitation processes. Internal conversion and intersystem crossing also dissipates excitation energy. These three processes are called as 'basal dissipation'. In addition to basal dissipation, excitation energy is consumed to drive 'photochemistry' (photosynthetic electron transport). Under illumination, a mechanism called as 'non-photochemical quenching' is induced by biochemical mechanisms and dissipates excessive energy as heat. Based on the Stern-Volmer relationship between fluorescence intensity and de-excitation rate constants, relative sizes of rate constants for these de-excitation pathways (basal dissipation, photochemistry and non-photochemical quenching) can be calculated by the technique called as Pulse Amplitude Modulation (PAM). In the PAM analysis of chlorophyll fluorescence, yield of fluorescence is measured with weak pulses of illumination. PAM technique enables measurement of fluorescence yield under both dark and illuminated conditions. Illumination of the leaf results in decrease of photochemistry and increase of non-photochemical quenching. Such changes are measured by several fluorescence parameters. The principle equation to calculate relative sizes of rate constants from chlorophyll fluorescence intensities was presented by Kitajima and Butler. Since Kitajima and Butler, PAM was introduced and non-photochemical quenching was discovered, thus the principle equation was updated. This updated principle equation will be referred to as 'Kitajima-Butler equation' in this review. Many fluorescence parameters have been proposed from calculation of Kitajima-Butler equation. These parameters were first represented by complex formulas, and recent finding even showed that relative sizes of rate constants of all de-excitation pathways are easily described as the comparison between inverse values of fluorescence intensities. PAM fluorescence analysis provides high-throughput method to estimate photosynthetic rate, damage by stressful conditions (photoinhibition) and size of non-photochemical quenching in living plant leaves. PAM fluorescence measurement is routinely used to estimate and visualize the effects of plant genes or stress treatments on these processes. © 2011 by Nova Science Publishers, Inc. All rights reserved.
  SCOPUS ID：84892840962
• 雑草のメタボローム研究〔2〕—環境ストレス耐性とバイオマスエネルギー素材—　　　　　　　　　　　　　　　
  宮城敦子; 川合真紀; 内宮博文
  農業および園芸, 巻：86, 号：11, 開始ページ：1153-1159, 2011年11月
  日本語
  ISSN：0369-5247, J-Global ID：201102253283160276
• 雑草のメタボローム研究〔1〕—タデ科植物種間比較解析—　　　　　　　　　　　　　　　
  宮城敦子; 川合真紀; 内宮博文
  農業および園芸, 巻：86, 号：10, 開始ページ：1062-1066, 2011年10月
  日本語
  ISSN：0369-5247, J-Global ID：201102266438000976
• シロイヌナズナにおけるNAD合成酵素の過剰発現は老化を促進する　　　　　　　　　　　　　　　
  橋田慎之介; 高原健太郎; 淨閑正史; 庄子和博; 後藤文之; 吉原利一; 川合(山田)真紀; 内宮博文; 内宮博文
  日本植物生理学会年会要旨集, 巻：52nd, 開始ページ：742, 終了ページ：742, 2011年
  NAD(H)やNADP(H)は細胞内の酸化還元反応に不可欠な補酵素であり、植物生長制御や環境適応性において重要な役割を担う。これまでに我々のグループではNAD前駆体の合成酵素遺伝子（NMNAT）やNADP合成酵素遺伝子(NADK2)を過剰発現する植物体を作出し、様々な環境ストレス耐性が付与される事を報告した。本研究ではNAD合成酵素遺伝子(NADS)を過剰発現するシロイヌナズナを作出し新たな表現型が観察されたので報告する。栄養生長期のNADS過剰発現株ではNADS合成酵素活性が41～72%増加していたが、NAD(H)およびNADP(H)量に変化はなく、野生型株と比較して顕著な表現型差異は観察されなかった。この時、NAD前駆体とNAD分解産物の蓄積およびサルベージNAD生合成経路の遺伝子発現が誘導されていたことから、NADS過剰発現株ではNAD代謝回転も同時に促進されることでNAD恒常性が維持されると考えられた。これに対して生殖生長期のNADS過剰発現株では老化進行が促進され、ほとんどの個体は開花前に死滅した。抽苔前後のNAD(H)およびNADP(H)量を比較すると、抽苔後のNADS過剰発現株ではNAD+分解が促進されていた。本講演ではその他の一次代謝産物の解析結果と併せてNAD恒常性と老化との関連について議論する予定である。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2011.0.0742.0
  DOI ID：10.14841/jspp.2011.0.0742.0, J-Global ID：201102296779639831, CiNii Articles ID：130006998144
• Loss of Calmodulin Binding to Bax Inhibitor-1 Affects Pseudomonas-mediated Hypersensitive Response-associated Cell Death in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Maki Kawai-Yamada; Zenta Hori; Taro Ogawa; Yuri Ihara-Ohori; Katsunori Tamura; Minoru Nagano; Toshiki Ishikawa; Hirofumi Uchimiya
  巻：284, 号：41, 開始ページ：27998, 終了ページ：28003, 2009年10月
  Bax inhibitor-1 (BI-1) is a cell death suppressor protein conserved across a variety of organisms. The Arabidopsis atbi1-1 plant is a mutant in which the C-terminal 6 amino acids of the expressed BI-1 protein have been replaced by T-DNA insertion. This mutant BI-1 protein (AtBI-CM) produced in Escherichia coli can no longer bind to calmodulin. A promoter-reporter assay demonstrated compartmentalized expression of BI-1 during hypersensitive response, introduced by the inoculation of Pseudomonas syringae possessing the avrRTP2 gene, Pst(avr-RPT2). In addition, both BI-1 knockdown plants and atbi1-1 showed increased sensitivity to Pst(avrRPT2)-induced cell death. The results indicated that the loss of calmodulin binding reduces the cell death suppressor activity of BI-1 in planta.
  英語
  DOI：https://doi.org/10.1074/jbc.M109.037234
  DOI ID：10.1074/jbc.M109.037234, ISSN：0021-9258, CiNii Articles ID：80020605891, PubMed ID：19674971, Web of Science ID：WOS:000270676300028
• Estimation of the Relative Sizes of Rate Constants for Chlorophyll De-excitation Processes Through Comparison of Inverse Fluorescence Intensities　　　　　　　　　　　　　　　
  Ichiro Kasajima; Kentaro Takahara; Maki Kawai-Yamada; Hirofumi Uchimiya
  巻：50, 号：9, 開始ページ：1600, 終了ページ：1616, 2009年09月
  The paper derives a simple way to calculate the linear relationships between all separable groups of rate constants for de-excitation of Chl a excitation energy. This is done by comparison of the inverse values of chlorophyll fluorescence intensities and is based on the matrix model of Kitajima and Butter and on the take model of energy exchange among PSII centers. Compared with the outputs of earlier, similar calculations, the results presented here add some linear comparisons of the relative sizes of rate constants without the need for F(0)' measurement. This enables us to regenerate the same alternative formula to calculate q(L), as presented previously, in a different and simple form. The same former equation to calculate F(0)' value from F(m), F(m)' and F(0) values is also regenerated in our calculation system in a simple form. We also apply relaxation analysis to separate the rate constant for non-photochemical quenching (k(NPQ)) into the rate constant for a fast-relaxing non-photochemical quenching (k(fast)) and the rate constant for slow-relaxing non-photochemical quenching (k(slow)). Changes in the sizes of rate constants were measured in Arabidopsis thaliana and in rice.
  英語
  DOI：https://doi.org/10.1093/pcp/pcp102
  DOI ID：10.1093/pcp/pcp102, ISSN：0032-0781, CiNii Articles ID：10027343022, PubMed ID：19602498, Web of Science ID：WOS:000270547300003
• Pleiotropic Modulation of Carbon and Nitrogen Metabolism in Arabidopsis Plants Overexpressing the NAD kinase2 Gene　　　　　　　　　　　　　　　
  Hideyuki Takahashi; Kentaro Takahara; Shin-nosuke Hashida; Takayuki Hirabayashi; Tamaki Fujimori; Maki Kawai-Yamada; Tomoyuki Yamaya; Shuichi Yanagisawa; Hirofumi Uchimiya
  巻：151, 号：1, 開始ページ：100, 終了ページ：113, 2009年09月
  Nicotinamide nucleotides (NAD and NADP) are important cofactors in many metabolic processes in living organisms. In this study, we analyzed transgenic Arabidopsis (Arabidopsis thaliana) plants that overexpress NAD kinase2 (NADK2), an enzyme that catalyzes the synthesis of NADP from NAD in chloroplasts, to investigate the impacts of altering NADP level on plant metabolism. Metabolite profiling revealed that NADP(H) concentrations were proportional to NADK activity in NADK2 overexpressors and in the nadk2 mutant. Several metabolites associated with the Calvin cycle were also higher in the overexpressors, accompanied by an increase in overall Rubisco activity. Furthermore, enhanced NADP(H) production due to NADK2 overexpression increased nitrogen assimilation. Glutamine and glutamate concentrations, as well as some other amino acids, were higher in the overexpressors. These results indicate that overexpression of NADK2 either directly or indirectly stimulates carbon and nitrogen assimilation in Arabidopsis under restricted conditions. Importantly, since neither up-regulation nor down-regulation of NADK2 activity affected the sum amount of NAD and NADP or the redox state, the absolute level of NADP and/or the NADP/NAD ratio likely plays a key role in regulating plant metabolism.
  英語
  DOI：https://doi.org/10.1104/pp.109.140665
  DOI ID：10.1104/pp.109.140665, ISSN：0032-0889, CiNii Articles ID：80020615084, PubMed ID：19587098, Web of Science ID：WOS:000269522200009
• A gene encoding SMALL ACIDIC PROTEIN 2 potentially mediates the response to synthetic auxin, 2,4-dichlorophenoxyacetic acid, in Arabidopsis thaliana.　　　　　　　　　　　　　　　
  Akari Nakasone; Maki Kawai-Yamada; Tomohiro Kiyosue; Issay Narumi; Hirofumi Uchimiya; Yutaka Oono
  巻：166, 号：12, 開始ページ：1307, 終了ページ：13, 2009年08月15日, ［国際誌］
  The SMALL ACIDIC PROTEIN 2 (SMAP2) gene is a paralogue of the SMAP1 gene that mediates the response to the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) in the root of Arabidopsis thaliana. Their encoded proteins, SMAP1 and SMAP2, are similar in calculated molecular weight and isoelectric point, and in having a highly conserved phenylalanine and aspartic acid-rich domain. RNA expression analysis showed that SMAP1 mRNA is present throughout the plant body while SMAP2 mRNA is restricted to siliques and anthers. Over-expression of the SMAP2 gene, as well as SMAP1, by 35S cauliflower mosaic virus promoter restored sensitivity to 2,4-D in the 2,4-D-resistant mutant, aar1, which is defective in SMAP1 function. The results suggest that SMAP2 has an ability to mediate the 2,4-D response and is expressed only in restricted tissues.
  英語
  DOI：https://doi.org/10.1016/j.jplph.2009.02.005
  DOI ID：10.1016/j.jplph.2009.02.005, PubMed ID：19307045
• Functional association of cell death suppressor, Arabidopsis Bax inhibitor-1, with fatty acid 2-hydroxylation through cytochrome b(5)　　　　　　　　　　　　　　　
  Minoru Nagano; Yuri Ihara-Ohori; Hiroyuki Imai; Noriko Inada; Masaru Fujimoto; Nobuhiro Tsutsumi; Hirofumi Uchimiya; Maki Kawai-Yamada
  巻：58, 号：1, 開始ページ：122, 終了ページ：134, 2009年04月
  Bax inhibitor-1 (BI-1) is a widely conserved cytoprotective protein localized in the endoplasmic reticulum (ER) membrane. We identified Arabidopsis cytochrome b(5) (AtCb5) as an interactor of Arabidopsis BI-1 (AtBI-1) by screening the Arabidopsis cDNA library with the split-ubiquitin yeast two-hybrid (suY2H) system. Cb5 is an electron transfer protein localized mainly in the ER membrane. In addition, a bimolecular fluorescence complementation (BiFC) assay and fluorescence resonance energy transfer (FRET) analysis confirmed that AtBI-1 interacted with AtCb5 in plants. On the other hand, we found that the AtBI-1-mediated suppression of cell death in yeast requires Saccharomyces cerevisiae fatty acid hydroxylase 1 (ScFAH1), which had a Cb5-like domain at the N terminus and interacted with AtBI-1. ScFAH1 is a sphingolipid fatty acid 2-hydroxylase localized in the ER membrane. In contrast, AtFAH1 and AtFAH2, which are functional ScFAH1 homologues in Arabidopsis, had no Cb5-like domain, and instead interacted with AtCb5 in plants. These results suggest that AtBI-1 interacts with AtFAHs via AtCb5 in plant cells. Furthermore, the overexpression of AtBI-1 increased the level of 2-hydroxy fatty acids in Arabidopsis, indicating that AtBI-1 is involved in fatty acid 2-hydroxylation.
  英語
  DOI：https://doi.org/10.1111/j.1365-313X.2008.03765.x
  DOI ID：10.1111/j.1365-313X.2008.03765.x, ISSN：0960-7412, eISSN：1365-313X, Web of Science ID：WOS:000264612800010
• 2,4‐D応答に関わるタンパク質,Small Acidic Protein 1(SMAP1)はCOP9シグナロソーム(CSN)と結合する
  中曽根光; 川合真紀; 鳴海一成; 内宮博文; 大野豊
  日本植物生理学会年会要旨集, 巻：50th, 開始ページ：250, 2009年03月16日
  日本語
  J-Global ID：200902220454582383
• CO2 regulator SLAC1 and its homologues are essential for anion homeostasis in plant cells　　　　　　　　　　　　　　　
  Juntaro Negi; Osamu Matsuda; Takashi Nagasawa; Yasuhiro Oba; Hideyuki Takahashi; Maki Kawai-Yamada; Hirofumi Uchimiya; Mimi Hashimoto; Koh Iba
  巻：452, 号：7186, 開始ページ：483, 終了ページ：U13, 2008年03月
  The continuing rise in atmospheric [ CO2] is predicted to have diverse and dramatic effects on the productivity of agriculture, plant ecosystems and gas exchange(1-3). Stomatal pores in the epidermis provide gates for the exchange of CO2 and water between plants and the atmosphere, processes vital to plant life(4-6). Increased [ CO2] has been shown to enhance anion channel activity(7) proposed to mediate efflux of osmoregulatory anions ( Cl- and malate(2-)) from guard cells during stomatal closure(8,9). However, the genes encoding anion efflux channels in plant plasma membranes remain unknown. Here we report the isolation of an Arabidopsis gene, SLAC1 ( SLOW ANION CHANNEL-ASSOCIATED 1, At1g12480), which mediates CO2 sensitivity in regulation of plant gas exchange. The SLAC1 protein is a distant homologue of bacterial and fungal C4- dicarboxylate transporters, and is localized specifically to the plasma membrane of guard cells. It belongs to a protein family that in Arabidopsis consists of four structurally related members that are common in their plasma membrane localization, but show distinct tissue- specific expression patterns. The loss- of- function mutation in SLAC1 was accompanied by an over- accumulation of the osmoregulatory anions in guard cell protoplasts. Guard- cell- specific expression of SLAC1 or its family members resulted in restoration of the wild- type stomatal responses, including CO2 sensitivity, and also in the dissipation of the over- accumulated anions. These results suggest that SLAC1-family proteins have an evolutionarily conserved function that is required for the maintenance of organic/ inorganic anion homeostasis on the cellular level.
  英語
  DOI：https://doi.org/10.1038/nature06720
  DOI ID：10.1038/nature06720, ISSN：0028-0836, CiNii Articles ID：80019383908, PubMed ID：18305482, Web of Science ID：WOS:000254341300034
• The cell death factor, cell wall elicitor of rice blast fungus (Magnaporthe grisea) causes metabolic alterations including GABA shunt in rice cultured cells　　　　　　　　　　　　　　　
  Hideyuki Takahashi; Hideo Matsumura; Maki Kawai-Yamada; Hirofumi Uchimiya
  巻：3, 号：11, 開始ページ：945, 終了ページ：953, 2008年
  An elicitor derived from the cell wall of rice blast fungus (Magnaporthe grisea) causes cell death in suspension cultured cells of rice (Oryza sativa L.). To elucidate the role of M. grisea elicitor on metabolic pathway of rice cells, we performed metabolite profiling using capillary electrophoresis-mass spectrometry (CE/MS). Treatment with M. grisea elicitor increased the amounts of antioxidants and free amino acids and decreased the amount of metabolites in the tricarboxylic acid (TCA) cycle. Lower ATP concentration caused aberrant energy charge, concurrently with reduced amount of NAD(P)H in elicitor treated cells. Among free amino acids detected in this study, the level of gamma-aminobutyric acid (GABA) increased. GABA is metabolized through a bypass pathway of the TCA cycle called GABA shunt, which is composed of glutamate decarboxylase (GAD), GABA transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH). While M. grisea elicitor negligibly affected GAD and SSADH, GABA-T activity significantly decreased. The decrease in GABA-T activity was recovered by NADPH oxidase inhibitor, which prevents cell death induced by M. grisea elicitor. Thus, GABA accumulation observed in rice cells under elicitor stress is partly associated with GABA-T activity. ©2008 Landes Bioscience.
  英語
  DOI：https://doi.org/10.4161/psb.6112
  DOI ID：10.4161/psb.6112, ISSN：1559-2324, SCOPUS ID：56049093502
• The bax inhibitor-1 needs a functional electron transport chain for cell death suppression　　　　　　　　　　　　　　　
  Reiko Oshima; Keiko Yoshinaga; Yuri Ihara-Hori; Ryouichi Fukuda; Akinori Ohta; Hirofumi Uchimiya; Maki Kawai-Yamada
  巻：581, 号：24, 開始ページ：4627, 終了ページ：4632, 2007年10月
  Bax inhibitor-1 (BI-1) is an evolutionarily conserved cell death suppresser in animals, yeast, and plants. In this study, yeast strains carrying single-gene deletions were screened for factors related to cell death suppression by Arabidopsis BI-1 (AtBI-1). Our screen identified mutants that failed to survive Bax-induced lethality even with AtBI-1 coexpression (Bax suppressor). The Delta cox16 strain was isolated as a BI-1-inactive mutant; it was disrupted in a component of the mitochondrial cytochrome c oxidase. Other mutants defective in mitochondrial electron transport showed a similar phenotype. ATP levels were markedly decreased in all these mutants, suggesting that BI-1 requires normal electron transport activity to suppress cell death in yeast. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
  英語
  DOI：https://doi.org/10.1016/j.febslet.2007.08.054
  DOI ID：10.1016/j.febslet.2007.08.054, ISSN：0014-5793, CiNii Articles ID：80018237639, PubMed ID：17825821, Web of Science ID：WOS:000250102900014
• Arabidopsis thaliana nicotinate/nicotinamide mononucleotide adenyltransferase (AtNMNAT) is required for pollen tube growth　　　　　　　　　　　　　　　
  Shin-nosuke Hashida; Hideyuki Takahashi; Maki Kawai-Yamada; Hirofumi Uchimiya
  巻：49, 号：4, 開始ページ：694, 終了ページ：703, 2007年02月
  While mammals and fungi possess nicotinate/nicotinamide mononucleotide adenyltransferase (NMNAT) isoforms, Arabidopsis thaliana only contains a single NMNAT gene, AtNMNAT (At5g55810). We analyzed the enzymatic activity of the AtNMNAT-encoded protein to determine the role of AtNMNAT in plant development. AtNMNAT catalyzed the synthesis of nicotinate adenine dinucleotide (NaAD) from nicotinate mononucleotide (NaMN) in the Preiss-Handler-dependent pathway, and of nicotinamide adenine dinucleotide (NAD) from nicotiamide mononucleotide (NMN) in the Preiss-Handler-independent pathway. Prominent AtNMNAT expression was detected in the male gametophyte. Moreover, AtNMNAT expression was spatio-temporally regulated during microspore development and pollen tube growth. Disruption of the AtNMNAT gene (atnmnat mutant) was characterized by a decrease in NAD content in pollen. Cytological examinations revealed that the atnmnat mutant was gametophytically impaired in in vivo and in vitro pollen tube growth. Our results suggest that metabolic fulfillment via the NAD pathway is indispensable for normal pollen growth and subsequent normal seed production.
  英語
  DOI：https://doi.org/10.1111/j.1365-313X.2006.02989.x
  DOI ID：10.1111/j.1365-313X.2006.02989.x, ISSN：0960-7412, Web of Science ID：WOS:000244060500010
• Mutual regulation of Arabidopsis thaliana ethylene-responsive element binding protein and a plant floral homeotic gene, APETALA2　　　　　　　　　　　　　　　
  Taro Ogawa; Hirofumi Uchimiya; Maki Kawai-Yamada
  巻：99, 号：2, 開始ページ：239, 終了ページ：244, 2007年02月
  Background and Aims It has previously been shown that Arabidopsis thaliana ethylene-responsive element binding protein (AtEBP) contributed to resistance to abiotic stresses. Interestingly, it has also been reported that expression of ethylene-responsive factor (ERF) genes including AtEBP were regulated by the activity of APETALA2 (AP2), a floral homeotic factor. AP2 is known to regulate expression of several floral-specific homeotic genes such as AGAMOUS. The aim of this study was to clarify the relationship between AP2 and AtEBP in Gene expression.
  Methods Northern blot analysis was performed on ap2 mutants, ethylene-related Arabidopsis mutants and transgenic Arabidopsis plants over-expressing AtEBP, and a T-DNA insertional mutant of AtEBP. Phenotypic analysis of these plants was performed.
  Key Results Expression levels of ERF genes such as AtEBP and AtERF1 were increased in ap2 mutants. Over-expression of AtEBP caused upregulation of AP2 expression in leaves. AP2 expression was suppressed by the null-function of ethylene-insensitive2 (EIN2), although AP2 expression was not affected by ethylene treatment. Loss of AtEBP function slightly reduced the average number of stamens.
  Conclusions AP2 and AtEBP are mutually regulated in terms of gene expression. AP2 expression was affected by EIN2 but was not regulated by ethylene treatment.
  英語
  DOI：https://doi.org/10.1093/aob/mcl265
  DOI ID：10.1093/aob/mcl265, ISSN：0305-7364, PubMed ID：17204538, Web of Science ID：WOS:000244566000004
• Cell death suppressor Arabidopsis Bax inhibitor-1 is associated with calmodulin binding and ion homeostasis　　　　　　　　　　　　　　　
  Yuri Ihara-Ohori; Minoru Nagano; Shoshi Muto; Hirofumi Uchimiya; Maki Kawai-Yamada
  巻：143, 号：2, 開始ページ：650, 終了ページ：660, 2007年02月
  Cell death suppressor Bax inhibitor-1 (BI-1), an endoplasmic reticulum membrane protein, exists in a wide range of organisms. The split-ubiquitin system, overlay assay, and bimolecular fluorescence complementation analysis demonstrated that Arabidopsis (Arabidopsis thaliana) BI-1 (AtBI-1) interacted with calmodulin in yeast (Saccharomyces cerevisiae) and in plant cells. Furthermore, AtBI-1 failed to rescue yeast mutants lacking Ca2+ ATPase (Pmr1 or Spf1) from Bax-induced cell death. Pmr1 and Spf1, p-type ATPases localized at the inner membrane, are believed to be involved in transmembrane movement of calcium ions in yeast. Thus, the presence of intact Ca2+ ATPases was essential for AtBI-1-mediated cell death suppression in yeast. To investigate the effect of AtBI-1 on calcium homeostasis, we evaluated sensitivity against cyclopiazonic acid (CPA), an inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase in AtBI-1-overexpressing or knock-down transgenic Arabidopsis plants. These plants demonstrated altered CPA or ion stress sensitivity. Furthermore, AtBI-1-overexpressing cells demonstrated an attenuated rise in cytosolic calcium following CPA or H2O2 treatment, suggesting that AtBI-1 affects ion homeostasis in plant cell death regulation.
  英語
  DOI：https://doi.org/10.1104/pp.106.090878
  DOI ID：10.1104/pp.106.090878, ISSN：0032-0889, CiNii Articles ID：80017879340, PubMed ID：17142482, Web of Science ID：WOS:000244032400011
• Chloroplast NADK is necessary for regulation of carbon and nitrate metabolism　　　　　　　　　　　　　　　
  Hideyuki Takahashi; Sin-nosuke Hashida; Ayumi Tanaka; Kintake Sonoike; Maki Kawai; Hirofumi Uchimiya
  巻：48, 開始ページ：S43, 終了ページ：S43, 2007年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000245922700167
• Chloroplast NAD kinase is essential for energy transduction through the xanthophyll cycle in photosynthesis　　　　　　　　　　　　　　　
  Hideyuki Takahashi; Ayako Watanabe; Ayumi Tanaka; Shin-nosuke Hashida; Maki Kawai-Yamada; Kintake Sonoike; Hirofumi Uchimiya
  巻：47, 号：12, 開始ページ：1678, 終了ページ：1682, 2006年12月
  Photosynthetic parameters of the nadk2 mutant of Arabidopsis thaliana, which is defective in chloroplast NAD kinase, were investigated. In this plant, the effective efficiency of photosynthetic electron transport (Phi II) and the quantum yield of open reaction centers of photosystem II (Fv'/Fm') were decreased. Furthermore, an increase in nonphotochemical quenching attributed to energy dissipation from the xanthophyll cycle was observed. The mutant showed an aberrant de-epoxidation state of xanthophyll cycle carotenoids and had a high level of zeaxanthin even under low light conditions. These results indicate that chloroplast NAD kinase, catalyzing phosphorylation of NAD, is essential for the proper photosynthetic machinery of PSII and the xanthophyll cycle.
  英語
  DOI：https://doi.org/10.1093/pcp/pcl029
  DOI ID：10.1093/pcp/pcl029, ISSN：0032-0781, CiNii Articles ID：10018809609, PubMed ID：17082216, Web of Science ID：WOS:000243131300010
• Evaluation of metabolic alteration in transgenic rice overexpressing dihydroflavonol-4-reductase　　　　　　　　　　　　　　　
  Hideyuki Takahashi; Mitsunori Hayashi; Fumiyuki Goto; Shigeru Sato; Tomoyoshi Soga; Takaaki Nishioka; Masaru Tomita; Maki Kawai-Yamada; Hirofumi Uchimiya
  巻：98, 号：4, 開始ページ：819, 終了ページ：825, 2006年10月
  center dot Background and Aims Previous studies have shown that transgenic rice plants overexpressing YK1, which possesses dihydroflavonol-4-reductase (DFR) activity, showed biotic and abiotic stress tolerance. High throughput profiles of metabolites have also been shown in such transgenic plants by Fourier transform ion cyclotron mass spectrometry. In this study, capillary electrophoresis mass spectrometry analysis (CE/MS) was employed to identify precise metabolites such as organic acids, amino acids and sugars.
  center dot Methods Using CE/MS, we analysed several metabolites of glycolysis, the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway. In addition, the concentrations of sugars and ion were quantified.
  center dot Key Results In YK1 (DFR)-overexpressing plants, the concentrations of cis-aconitate, isocitrate and 2-oxoglutarate were higher in leaves, whereas those of fructose-1,6-bisphosphate and glyceraldehyde-3-phosphate were lower in roots. In seeds, the amounts of free amino acids and metals were altered, whereas sugars in seeds were kept constant. In YK1 calli, an approx. 3-fold increase in glutathione was observed, whereas the activities of glutathione peroxidase and glutathione reductase were concomitantly increased.
  center dot Conclusions The overexpression of YK1 (DFR) was associated with slight changes in the amounts of several metabolites analysed in whole plants, whilst glutathione derivatives were substantially increased in suspension-cultured cells.
  英語
  DOI：https://doi.org/10.1093/aob/mcl162
  DOI ID：10.1093/aob/mcl162, ISSN：0305-7364, eISSN：1095-8290, CiNii Articles ID：30022963309, PubMed ID：16849376, Web of Science ID：WOS:000240925800010
• Abolition of the tapetum suicide program ruins microsporogenesis　　　　　　　　　　　　　　　
  Takahiro Kawanabe; Tohru Ariizumi; Maki Kawai-Yamada; Hirofumi Uchimiya; Kinya Toriyama
  巻：47, 号：6, 開始ページ：784, 終了ページ：787, 2006年06月
  Microsporogenesis in angiosperms takes places within the anther. Microspores are surrounded by a layer of cells, the tapetum, which degenerates during the later stages of pollen development with cytological features characteristic of programmed cell death (PCD). We report herein that the expression of AtBI-1, which suppresses Bax-induced cell death, in the tapetum at the tetrad stage inhibits tapetum degeneration and subsequently results in pollen abortion, while activation of AtBI-1 at the later stage does not. Our results demonstrate that the PCD signal commences at the tetrad stage and that the proper timing of PCD in the tapetum is essential for normal microsporogenesis.
  英語
  DOI：https://doi.org/10.1093/pcp/pcj039
  DOI ID：10.1093/pcp/pcj039, ISSN：0032-0781, CiNii Articles ID：10017602383, PubMed ID：16565524, Web of Science ID：WOS:000238538300013
• The mitochondrial fission regulator DRP3B does not regulate cell death in plants　　　　　　　　　　　　　　　
  Keiko Yoshinaga; Masaru Fujimoto; Shin-ichi Arimura; Nobuhiro Tsutsumi; Hirofumi Uchimiya; Maki Kawai-Yamada
  巻：97, 号：6, 開始ページ：1145, 終了ページ：1149, 2006年06月
  e Background and Aims Recent reports have described dramatic alterations in mitochondrial morphology during metazoan apoptosis. A dynamin-related protein (DRP) associated with mitochondrial outer membrane fission is known to be involved in the regulation of apoptosis. This study analysed the relationship between mitochondrial fission and regulation of plant cell death.
  center dot Methods Transgenic plants were generated possessing Arabidopsis DRP3B (K56A), the dominant-negative form of Arabidopsis DRP, mitochondrial-targeted green fluorescent protein and mouse Bax.
  center dot Key Results Arabidopsis plants over-expressing DRP3B (K56A) exhibited long tubular mitochondria. In these plants, mitochondria appeared as a string-of-beads during cell death. This indicates that DRP3B (K56A) prevented mitochondrial fission during plant cell death. However, in contrast to results for mammalian cells and yeast, Bax-induced cell death was not inhibited in DRP3B (K56A)-expressing plant cells. Similarly, hydrogen peroxide-, menadione, darkness- and salicylic acid-induced cell death was not inhibited by DRP3B (K56A) expression.
  center dot Conclusions These results indicate that the systems controlling cell death in animals and plants are not common in terms of mitochondrial fission.
  英語
  DOI：https://doi.org/10.1093/aob/mcl057
  DOI ID：10.1093/aob/mcl057, ISSN：0305-7364, eISSN：1095-8290, CiNii Articles ID：10027345732, PubMed ID：16533833, Web of Science ID：WOS:000238816800023
• Arabidopsis transcriptional factor, AtEBP inhibited the hypersensitive response mediated by Pseudomonas syringae with an avirulent gene　　　　　　　　　　　　　　　
  T Ogawa; K Tamura; M Kawai; H Uchimiya
  巻：47, 開始ページ：S47, 終了ページ：S47, 2006年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000236401400186
• Analysis of calmodulin interacting with cell death suppressor (AtBI-1)　　　　　　　　　　　　　　　
  Z Hori; Y Ohori; H Uchimiya; M Kawai
  巻：47, 開始ページ：S43, 終了ページ：S43, 2006年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000236401400170
• A novel Arabidopsis gene causes Bax-like lethality in Saccharomyces cerevisiae　　　　　　　　　　　　　　　
  M Kawai-Yamada; Y Saito; LH Jin; T Ogawa; KM Kim; LH Yu; Y Tone; A Hirata; M Umeda; H Uchimiya
  巻：280, 号：47, 開始ページ：39468, 終了ページ：39473, 2005年11月
  Overexpression of the mammalian proapoptotic protein Bax induces cell death in plant and yeast cells. The Bax inihibitor-1 (BI-1) gene rescues yeast and plant from Bax-mediated lethality. Using the Arabidopsis BI-1 (AtBI-1) gene controlled by the GAL1 promoter as a cell death suppressor in yeast, Cdf1 ((c) under bar ell growth (d) under bar efect (f) under bar actor-(1) under bar) was isolated from Arabidopsis cDNA library. Overexpression of Cdf1 caused cell death in yeast, whereas such an effect was suppressed by co-expression of AtBI-1. The Cdf1 protein fused with a green fluorescent protein was localized in the mitochondria and resulted in the loss of mitochondrial membrane potential in yeast. The Bax-resistant mutant BRM1 demonstrated tolerance against Cdf1-mediated lethality, whereas the Delta atp4 strain was sensitive to Cdf1. Our results suggest that Cdf1 and Bax cause mitochondria-mediated yeast lethality through partially overlapped pathways.
  英語
  DOI：https://doi.org/10.1074/jbc.M509632200
  DOI ID：10.1074/jbc.M509632200, ISSN：0021-9258, CiNii Articles ID：80017727608, PubMed ID：16192270, Web of Science ID：WOS:000233362200068
• Mammalian Bax initiates plant cell death through organelle destruction　　　　　　　　　　　　　　　
  K Yoshinaga; S Arimura; A Hirata; Y Niwa; DJ Yun; N Tsutsumi; H Uchimiya; M Kawai-Yamada
  巻：24, 号：7, 開始ページ：408, 終了ページ：417, 2005年09月
  Mammalian Bax is known to cause cell death when expressed in plants. We examined transgenic plants expressing both Bax and organelle-targeted green fluorescent protein to determine the cellular changes that occur during Bax-induced cell death. The mitochondria changed morphologically from being bacilli-shaped to being round, eventually becoming swollen. Mitochondria streaming also stopped. The chloroplasts lost membrane function and their contents leaked out, followed by the disruption of the vacuole. Light was not essential for Bax-induced ion leakage or organelle disruption. These results indicate that Bax induces temporal and spatial cell death events at the organelle level in the plant. A heterologous system, using Bax, would therefor be available to investigate cell death, which is commonly conserved in animals and plants.
  英語
  DOI：https://doi.org/10.1007/s00299-005-0948-6
  DOI ID：10.1007/s00299-005-0948-6, ISSN：0721-7714, Web of Science ID：WOS:000232223000004
• Mitochondrial behaviour in the early stages of ROS stress leading to cell death in Arabidopsis thaliana　　　　　　　　　　　　　　　
  K Yoshinaga; SI Arimura; Y Niwa; N Tsutsumi; H Uchimiya; M Kawai-Yamada
  巻：96, 号：2, 開始ページ：337, 終了ページ：342, 2005年08月
  Background and Aims Reactive oxygen species (ROS) are involved in triggering cell death. To visualize mitochondrial behaviour under ROS stress, transgenic arabidopsis plants possessing mitochondrial-targeted GFP ( S65T) were studied.
  Methods Arabidopsis leaves were treated with ROS and ROS-inducing chemicals such as hydrogen peroxide, paraquat and menadione. Microscopic observations were carried out using a confocal laser scanning microscope system, and electrolyte leakage was also monitored.
  Key Results After treatment, mitochondria showed morphological changes from a bacillus- like to a round shape. The size of mitochondria treated with H2O2 decreased by half compared with controls. Concurrently, cytoplasmic streaming was blocked and mitochondria eventually swelled. Treatment of leaves with butanedione monoxime, an inhibitor of myosin ATPase, resulted in similar behaviour of mitochondria to that under ROS stress.
  Conclusions The results indicate that morphological changes of mitochondria and cessation of cytoplasmic streaming may interact, and this phenomenon is one of the features of ROS stress-induced cell death.
  英語
  DOI：https://doi.org/10.1093/aob/mci181
  DOI ID：10.1093/aob/mci181, ISSN：0305-7364, Web of Science ID：WOS:000230724400018
• Functional analysis of Arabidopsis ethylene-responsive element binding protein conferring resistance to Bax and abiotic stress-induced plant cell death　　　　　　　　　　　　　　　
  T Ogawa; L Pan; M Kawai-Yamada; LH Yu; S Yamamura; T Koyama; S Kitajima; M Ohme-Takagi; F Sato; H Uchimiya
  巻：138, 号：3, 開始ページ：1436, 終了ページ：1445, 2005年07月
  Arabidopsis ( Arabidopsis thaliana) ethylene-responsive element binding protein ( AtEBP) gene was isolated as a suppressor of Bax-induced cell death by functional screening in yeast ( Saccharomyces cerevisiae). To further examine the cell death suppressive action of AtEBP in plant cells, we established transgenic tobacco ( Nicotiana tabacum) plants overexpressing AtEBP as well as transgenic tobacco plants ectopically expressing mouse Bax protein under a dexamethasone-inducible promoter. We prepared the crosses of the selective lines of each transgenic plant, which were evaluated in terms of cell death suppression activity. Results indicate that AtEBP suppressed Bax- induced cell death in tobacco plants, an action also associated with a lowered level of ion leakage. Furthermore, tobacco Bright Yellow-2 cells overexpressing AtEBP conferred resistance to hydrogen peroxide ( H2O2) and heat treatments. AtEBP protein localized in the nucleus and functioned as an in vivo transcription activator as confirmed in transient assays and experiments using stable transgenic system. Up-regulation of defense genes was observed in transgenic Arabidopsis plants overexpressing AtEBP. Based on the analysis of mRNA accumulation in ethylene-related mutants, the position of AtEBP in signaling pathway is presented.
  英語
  DOI：https://doi.org/10.1104/pp.105.063586
  DOI ID：10.1104/pp.105.063586, ISSN：0032-0889, CiNii Articles ID：80017583019, PubMed ID：15980186, Web of Science ID：WOS:000230414800024
• Enhanced dihydroflavonol-4-reductase activity and NAD homeostasis leading to cell death tolerance in transgenic rice　　　　　　　　　　　　　　　
  M Hayashi; H Takahashi; K Tamura; Huang, JR; LH Yu; M Kawai-Yamada; T Tezuka; H Uchimiya
  巻：102, 号：19, 開始ページ：7020, 終了ページ：7025, 2005年05月
  The maize Hm1 gene encoding the NADPH-dependent HC-toxin reductase is capable of detoxifying HC-toxin of fungus Cochliobolus carbonum. Here, we conducted the metabolic and biochemical analysis in transgenic rice plants overexpressing an HC-toxin reductase-like gene in rice (YK1 gene). Methods employing NADPH oxidation and capillary electrophoresis mass spectrometry analysis confirmed that YK1 possessed dihydroflavonol-4-reductase activity in vitro and in vivo. The overexpression of YK1 in both suspension-cultured cells and rice plants increased NAD(H) and NADP(H) levels by causing an increase in NAD synthetase and NAD kinase activities. Activity changes in enzymes that require NAD(P) as coenzymes were also noted in rice cells ectopically expressing YK1, where the cell death caused by hydrogen peroxide and bacterial disease was down-regulated. Thus, a strategy was proposed that the combination of dihydroflavonol-4-reductase activity and the elevated level of NAD(P)H pool may confer the prevention of induced cell death in planta.
  英語
  DOI：https://doi.org/10.1073/pnas.0502556102
  DOI ID：10.1073/pnas.0502556102, ISSN：0027-8424, CiNii Articles ID：80017290330, PubMed ID：15863611, Web of Science ID：WOS:000229048500068
• Analysis of mitochondrial changes in Arabidopsis thaliana during ROS induced cell death　　　　　　　　　　　　　　　
  K Yoshinaga; M Kawai; S Arimura; M Fujimoto; N Tsutsumi; H Uchimiya
  巻：46, 開始ページ：S200, 終了ページ：S200, 2005年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000228104101303
• The stress response of Arabidopsis transcriptional factor AtEBP　　　　　　　　　　　　　　　
  T Ogawa; LH Yu; M Kawai; H Uchimiya
  巻：46, 開始ページ：S199, 終了ページ：S199, 2005年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000228104101300
• Maize plants mutated in NAD(P)H-dependent HC-toxin reductase gene (Hm1) is vulnerable to H2O2 stress　　　　　　　　　　　　　　　
  Mitsunori Hayashi; Hideyuki Takahashi; Maki Kawai-Yamada; Takafumi Tezuka; Hirofumi Uchimiya
  巻：22, 号：1, 開始ページ：69, 終了ページ：70, 2005年
  Maize Hm1 gene encodes a NAD(P)H-dependent HC-toxin reductase, which detoxify HC-toxin produced by fungus Cochliobolus carbonum (Meeley and Walton 1991 Plant Phys 97: 1080). Measurements of ion leakage indicated that H 2O2 treatment of a recessive mutant (hm1) of maize resulted in accelerated death in excised leaves. Furthermore, an hm1 maize showed quantitative decrease of NAD(H) level. Thus, the Hm1 gene may confer other functions related to ROS stress tolerance. Copyright © 2005 The Japanese Society for Plant Cell and Molecular Biology.
  英語
  DOI：https://doi.org/10.5511/plantbiotechnology.22.69
  DOI ID：10.5511/plantbiotechnology.22.69, ISSN：1347-6114, CiNii Articles ID：10026526470, SCOPUS ID：18744402810
• High throughput metabolome and proteome analysis of transgenic rice plants (Oryza sativa L.)　　　　　　　　　　　　　　　
  Hideyuki Takahashi; Yuji Hotta; Mitsunori Hayashi; Maki Kawai-Yamada; Setsuko Komatsu; Hirofumi Uchimiya
  巻：22, 号：1, 開始ページ：47, 終了ページ：50, 2005年
  We profiled metabolic patterns of transgenic rice organs and tissue by Fourier-transform ion cyclotron mass spectrometry (FT-MS) to reveal effects of the over-expression of repossessing high homology with maize HC-toxin reductase gene. Comparison of metabolic patterns revealed that compositions of organ- or tissue-specific metabolites were not significantly varied between the control and the YK1 rice, where expression levels of some metabolites were altered. Proteome analysis of cultured cells over-expressing YK1 showed the up-regulation of several stress-related proteins such as osmotin-like protein and osr40c1. Thus, alteration of metabolites as well as proteins may contribute to multiple stress tolerances in transgenic YK1 rice. Copyright © 2005 The Japanese Society for Plant Cell and Molecular Biology.
  英語
  DOI：https://doi.org/10.5511/plantbiotechnology.22.47
  DOI ID：10.5511/plantbiotechnology.22.47, ISSN：1347-6114, CiNii Articles ID：10026526399, SCOPUS ID：18744410743
• Oxidative stress and plant cell death suppressors　　　　　　　　　　　　　　　
  Maki Kawai-Yamada; Keiko Yoshinaga; Taro Ogawa; Yuri Ihara-Ohori; Hirofumi Uchimiya
  巻：22, 号：5, 開始ページ：419, 終了ページ：422, 2005年
  Classical yeast genetic approaches have been successfully applied for identification of genes related to the suppression of cell death. Isolated genes included several reactive oxygen species (ROS)-related genes such as SOD (superoxide dismutase), peroxidase, and GST (glutathione S-transferase). The AtBI-1 (Arabidopsis Bax Inhibitor-1), which is a plant homolog of mammalian antiapoptotic gene BI-1, was also isolated as a suppressor of Bax-mediated lethality in yeast. Overexpression of BI-1 suppresses Bax-, H2O 2-, salicylic acid-, and elicitor- induced cell death in plant cells. These data indicate conserved overlapping pathways that regulate ROS-mediated cell death in plants and animals.
  英語, 書評論文,書評,文献紹介等
  DOI：https://doi.org/10.5511/plantbiotechnology.22.419
  DOI ID：10.5511/plantbiotechnology.22.419, ISSN：1347-6114, CiNii Articles ID：10028054734, SCOPUS ID：30344438808
• Isolation and characterization of Arabidopsis thaliana ISU1 gene　　　　　　　　　　　　　　　
  Y Tone; M Kawai-Yamada; H Uchimiya
  巻：1680, 号：3, 開始ページ：171, 終了ページ：175, 2004年11月
  We describe the isolation of a cDNA encoding Arabidopsis thaliana ISU1 (AtISU1), which regulates iron homeostasis in the mitochondria. The AtISU1 gene contained an open reading frame that encoded 167 amino acid residues. Northern blot analysis demonstrated that AtISU1 gene was ubiquitously expressed in plant tissues examined. The yeast seo5-1, which harbors a single base-pair deletion in ScISU1, is a suppressor of oxidative damage in sod1-deficient mutant. Based on comparative expression analyses using yeast ISU1 gene (ScISU1) in seo5-1 mutant, we found that AtISU1 acts as a counterpart of ScISU1. (C) 2004 Elsevier B.V. All rights reserved.
  英語
  DOI：https://doi.org/10.1016/j.bbaexp.2004.09.005
  DOI ID：10.1016/j.bbaexp.2004.09.005, ISSN：0167-4781, Web of Science ID：WOS:000224938300004
• Bax-induced cell death of Arabidopsis is meditated through reactive oxygen-dependent and -independent processes　　　　　　　　　　　　　　　
  D Baek; J Nam; YD Koo; DH Kim; J Lee; JC Jeong; SS Kwak; WS Chung; CO Lim; JD Bahk; JC Hong; SY Lee; M Kawai-Yamada; H Uchimiya; DJ Yun
  巻：56, 号：1, 開始ページ：15, 終了ページ：27, 2004年09月
  An Arabidopsis protoplast system was developed for dissecting plant cell death in individual cells. Bax, a mammalian pro-apoptotic member of the Bcl-2 family, induces apoptotic-like cell death in Arabidopsis. Bax accumulation in Arabidopsis mesophyll protoplasts expressing murine Bax cDNA from a glucocorticoid-inducible promoter results in cytological characteristics of apoptosis, namely DNA fragmentation, increased vacuolation, and loss of plasma membrane integrity. In vivo targeting analysis monitored using jellyfish green fluorescent protein (GFP) reporter indicated full-length Bax was localized to the mitochondria, as it does in animal cells. Deletion of the carboxyl-terminal transmembrane domain of Bax completely abolished targeting to mitochondria. Bax expression was followed by reactive oxygen species (ROS) accumulation. Treatment of protoplasts with the antioxidant N-acetyl-L-cysteine (NAC) during induction of Bax expression strongly suppressed Bax-mediated ROS production and the cell death phenotype. However, some population of the ROS depleted cells still induced cell death, indicating that there is a process that Bax-mediated plant cell death is independent of ROS accumulation. Accordingly, suppression of Bax-mediated plant cell death also takes place in two different processes. Over-expression of a key redox-regulator, Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) down-regulated ROS accumulation and suppressed Bax-mediated cell death and transient expression of Arabidopsis Bax inhibitor-1 (AtBI-1) substantially suppressed Bax-induced cell death without altering cellular ROS level. Taken together, our results collectively suggest that the Bax-mediated cell death and its suppression in plants is mediated by ROS-dependent and -independent processes.
  英語
  DOI：https://doi.org/10.1007/s11103-004-3096-4
  DOI ID：10.1007/s11103-004-3096-4, ISSN：0167-4412, CiNii Articles ID：10028054735, PubMed ID：15604726, Web of Science ID：WOS:000225899900002
• Analysis of functional domains of cell death suppressor (AtBI-1)　　　　　　　　　　　　　　　
  Y Ohori; M Kawai; H Uchimiya
  巻：45, 開始ページ：S62, 終了ページ：S62, 2004年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000220592700244
• Functional analysis of Arabidopsis AtEBP in plants and stress responses　　　　　　　　　　　　　　　
  T Ogawa; LH Yu; M Ohme-Takagi; F Sato; M Kawai; H Uchimiya
  巻：45, 開始ページ：S50, 終了ページ：S50, 2004年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000220592700198
• Screening of Arabidopsis genes capable of inducing yeast cell death　　　　　　　　　　　　　　　
  M Kawai; Y Saitoh; K Yoshinaga; H Uchimiya
  巻：45, 開始ページ：S62, 終了ページ：S62, 2004年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000220592700245
• Dissection of Arabidopsis Bax inhibitor-1 suppressing Bax-, hydrogen peroxide-, and salicylic acid-induced cell death　　　　　　　　　　　　　　　
  M Kawai-Yamada; Y Ohori; H Uchimiya
  巻：16, 号：1, 開始ページ：21, 終了ページ：32, 2004年01月
  Overexpression of plant Bax Inhibitor-1 (BI-1) was able to suppress Bax-mediated cell death in yeast and Arabidopsis. Here, we demonstrate that reactive oxygen species production induced by the ectopic expression of Bax was insensitive to the coexpression of AtBI-1. Similarly, H2O2- or salicylic acid-mediated cell death also was suppressed in tobacco BY-2 cells overexpressing AtBI-1. To define the functional domain of AtBI-1 as a cell death suppressor, a truncated series of the AtBI-1 protein was analyzed in yeast possessing a galactose-inducible mammalian Bax. The results showed that DeltaC-AtBI-1 (with the C-terminal 14 amino acids deleted) lost the ability to sustain cell growth. Furthermore, a mutant protein in which the C-terminal seven amino acid residues of AtBI-1 were replaced with others lacking a coiled-coil structure failed to inhibit cell death, suggesting that the C-terminal region is essential for the inhibition of cell death. We also noted that the C-terminal hydrophilic region was interchangeable between animal and plant Bax inhibitors.
  英語
  DOI：https://doi.org/10.1105/tpc.014613
  DOI ID：10.1105/tpc.014613, ISSN：1040-4651, CiNii Articles ID：80016434021, PubMed ID：14671021, Web of Science ID：WOS:000188229000003
• Overexpression of Bax inhibitor suppresses the fungal elicitor-induced cell death in rice (Oryza sativa L.) cells　　　　　　　　　　　　　　　
  H Matsumura; S Nirasawa; A Kiba; N Urasaki; H Saitoh; M Ito; M Kawai-Yamada; H Uchimiya; R Terauchi
  巻：33, 号：3, 開始ページ：425, 終了ページ：434, 2003年02月
  Treatment of suspension-cultured cells of rice (Oryza sativa L.) with cell wall extract of rice blast fungus (Magnaporthe grisea ) elicits a rapid generation of H2O2, alkalinization of culture medium, and eventual cell death. To elucidate genes involved in these processes, we exploited SAGE (Serial Analysis of Gene Expression) technique for the molecular analysis of cell death in suspension-cultured cells treated with the elicitor. Among the downregulated genes in the elicitor-treated cells, a BI-1 gene coding for Bax inhibitor was identified. Transgenic rice cells overexpressing Arabidopsis BI-1 gene showed sustainable cell survival when challenged with M. grisea elicitor. Thus, the plant Bax inhibitor plays a functional role in regulating cell death in the rice cell culture system.
  英語
  DOI：https://doi.org/10.1046/j.1365-313X.2003.01639.x
  DOI ID：10.1046/j.1365-313X.2003.01639.x, ISSN：0960-7412, Web of Science ID：WOS:000180851300001
• A plant gene (AtBI-1) conferring elevated tolerance to ROS-induced cell death　　　　　　　　　　　　　　　
  M Kawai; H Uchimiya
  巻：44, 開始ページ：S207, 終了ページ：S207, 2003年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000181914300821
• Cellular dissection of bax-induced cell death in plants　　　　　　　　　　　　　　　
  K Yoshinaga; M Kawai; H Uchimiya
  巻：44, 開始ページ：S207, 終了ページ：S207, 2003年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000181914300820
• Glufosinate-tolerant tobacco plants directed by the promoter of adenylate kinase gene of rice　　　　　　　　　　　　　　　
  H Fukuzawa; S Arai; M Kawai-Yamada; A Das; M Tagawa; H Uchimiya
  巻：89, 号：3, 開始ページ：351, 終了ページ：354, 2002年03月
  A DNA clone containing the 5' part of the adenylate kinase (AK) gene was isolated from a rice genomic library, and its nucleotide sequence was determined. This clone consists of 5' upstream, five exons and four introns of the AK gene. All of the determined donor and receptor sites contained 'GT' and 'AG' consensus splice sequences. Transgenic tobacco plants harbouring a chimeric gene consisting of the 5' upstream sequence of the AK gene fused with the gene encoding phosphinothricin acetyl transferase were generated. They showed tolerance to glufosinate to a level four times higher than its commercial dose, (C) 2002 Annals of Botany Company.
  英語
  DOI：https://doi.org/10.1093/aob2002mcf041
  DOI ID：10.1093/aob2002mcf041, ISSN：0305-7364, Web of Science ID：WOS:000174774500012
• Induction of mammalian cell death by a plant Bax inhibitor　　　　　　　　　　　　　　　
  LH Yu; M Kawai-Yamada; M Naito; K Watanabe; JC Reed; H Uchimiya
  巻：512, 号：1-3, 開始ページ：308, 終了ページ：312, 2002年02月
  Arabidopsis thaliana AtBI-1 is an orthologue of mammalian Bax inhibitor-1 capable of suppressing Bax-induced cell death in yeast as well as mammalian cells. Here Ne investigated whether or not AtBI-1 suppresses Bax-induced cell death using human fibrosarcoma HT1080 cells. Surprisingly, AtBI-1 did not block Bax-induced cell death. but it triggered apoptotic cell death in mammalian cells. The proapoptotic effect of AtBI-I as blocked by the X-linked caspase inhibitor XIAP, suggesting that the cell death caused by AtBI-1 is similar to that caused by Bax. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
  英語
  DOI：https://doi.org/10.1016/S0014-5793(02)02230-5
  DOI ID：10.1016/S0014-5793(02)02230-5, ISSN：0014-5793, CiNii Articles ID：80015200913, PubMed ID：11852101, Web of Science ID：WOS:000174081900061
• Down-regulation of mammalian bax-induced plant cell death by Arabidopsis Bax inhibitor-1 (AtBI-1)　　　　　　　　　　　　　　　
  M Kawai; H Uchimiya
  巻：43, 開始ページ：S215, 終了ページ：S215, 2002年
  英語, 研究発表ペーパー・要旨（国際会議）
  ISSN：0032-0781, Web of Science ID：WOS:000174726400757
• Transgenic rice plants conferring increased tolerance to rice blast and multiple environmental stresses　　　　　　　　　　　　　　　
  H Uchimiya; S Fujii; Huang, JR; T Fushimi; M Nishioka; KM Kim; MK Yamada; T Kurusu; K Kuchitsu; M Tagawa
  巻：9, 号：1, 開始ページ：25, 終了ページ：31, 2002年
  We isolated a rice gene (denoted YK1), which showed 78 percent amino acid sequence homology to the maize HM1 gene. A chimeric gene consisting of a promoter and first intron of maize ubiquitin gene and the cDNA of YK1 was introduced into rice via Agrobacterium mediated transformation. Transgenic rice plants overexpressing this chimeric gene were resistant to rice blast (Magnaporthe grisea) disease, which is one of the most serious pathogens in rice. Furthermore, the same transgenic plants conferred high tolerance to several abiotic stresses such as NaCl, UV-C, submergence, and hydrogen peroxide.
  英語
  DOI：https://doi.org/10.1023/A:1019275218830
  DOI ID：10.1023/A:1019275218830, ISSN：1380-3743, Web of Science ID：WOS:000176505700003
• The Arabidopsis thaliana ethylene-responsive element binding protein (AtEBP) can function as a dominant suppressor of Bax-induced cell death of yeast　　　　　　　　　　　　　　　
  L Pan; M Kawai; LH Yu; KM Kim; A Hirata; M Umeda; H Uchimiya
  巻：508, 号：3, 開始ページ：375, 終了ページ：378, 2001年11月
  We identified genes based on screening of an Arabidopsis cDNA library for functional suppressors of mouse Bax-induced cell death of yeast cells. Interestingly, the cDNA encoding AtEBP, known as Arabidopsis thaliana ethylene-responsive element binding protein, was isolated numerous times in the functional screen (82% of all suppressors). Full-length AtEBP and its localization to the nucleus were essential for the suppression of Bax-induced cell death. Morphological abnormality of intracellular network that is a hallmark of Bax-induced cell death was attenuated by expression of AtEBP. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
  英語
  DOI：https://doi.org/10.1016/S0014-5793(01)03098-8
  DOI ID：10.1016/S0014-5793(01)03098-8, ISSN：0014-5793, CiNii Articles ID：80012784681, PubMed ID：11728455, Web of Science ID：WOS:000172416300020
• Mammalian Bax-induced plant cell death can be down-regulated by overexpression of Arabidopsis Bax Inhibitor-1 (AtBl-1)　　　　　　　　　　　　　　　
  M Kawai-Yamada; LH Jin; K Yoshinaga; A Hirata; H Uchimiya
  巻：98, 号：21, 開始ページ：12295, 終了ページ：12300, 2001年10月
  We recently isolated the AtBI-1 (Arabidopsis Bax Inhibitor-1) gene, the expression of which suppressed Bax-induced cell death in yeast. To determine whether the same is true in the plant system, transgenic Arabidopsis plants overexpressing Bax protein under a dexamethasone (DEX)-inducible promoter were generated. On DEX treatment, such transgenic plants exhibited marked cell death at the whole-plant level, cell shrinkage, membranous destruction, and other apoptotic phenotypes. Transgenic Bax plants were retransformed with a vector containing the AtBI-1 gene (tagged with green fluorescent protein) under the control of the cauliflower mosaic virus 35S promoter. Plants expressing both Bax and AtBI-1 were able to maintain growth on DEX-treatment by sustaining intracellular integrity. Thus, we present here direct genetic evidence that the plant antiapoptotic protein AtBI-1 is biologically active in suppressing the mammalian Bax action in planta.
  英語
  DOI：https://doi.org/10.1073/pnas.211423998
  DOI ID：10.1073/pnas.211423998, ISSN：0027-8424, CiNii Articles ID：80012776846, PubMed ID：11593047, Web of Science ID：WOS:000171558900085
• 植物の形態形成分子機構の研究 イオンビームによる植物細胞アポトーシス誘導体の確立
  川合真紀; 小林泰彦; 大野豊; 渡辺宏; 内宮博文
  基礎科学ノート, 巻：8, 号：1, 開始ページ：9, 終了ページ：12, 2001年03月
  日本語
  ISSN：1340-3079, J-Global ID：200902118512698355
• Nucleoside diphosphate kinase required for coleoptile elongation in rice　　　　　　　　　　　　　　　
  L Pan; M Kawai; A Yano; H Uchimiya
  巻：122, 号：2, 開始ページ：447, 終了ページ：452, 2000年02月
  Although several nucleoside diphosphate (NDP) kinase genes have been cloned in plants, little is known about the functional significance of this enzyme during plant growth and development. We introduced a chimeric gene encoding an antisense RNA of NDP kinase under the control of the Arabidopsis heat shock protein HSP81-1 promoter into rice (Oryza sativa L.) plants using the Agrobacterium tumefaciens transformation system. The expression of antisense RNA down-regulated the accumulation of mRNA, resulting in reduced enzyme activity even under the standard growth temperature (25 degrees C) in transgenic plants. Following heat shock treatment (37 degrees C), NDP kinase activities in some transgenic rice plants were more reduced than those grown under 25 degrees C. The comparison of the coleoptile growth under submersion showed that cell elongation process was inhibited in antisense NDP kinase transgenic plants, suggesting that an altered guanine nucleotide level may be responsible for the processes.
  英語
  DOI：https://doi.org/10.1104/pp.122.2.447
  DOI ID：10.1104/pp.122.2.447, ISSN：0032-0889, eISSN：1532-2548, CiNii Articles ID：80011516620, PubMed ID：10677437, Web of Science ID：WOS:000086903000014
• Coleoptile senescence in rice (Oryza sativa L.)　　　　　　　　　　　　　　　
  Maki Kawai; Hirofumi Uchimiya
  巻：86, 号：2, 開始ページ：405, 終了ページ：414, 2000年
  We investigated the cellular events associated with cell death in the coleoptile of rice plants (Oryza sativa L.). Seeds germinated under submergence produced coleoptiles that were more elongated than those grown under aerobic conditions. Transfer of seedlings to aerobic conditions was associated with coleoptile opening (i.e. splitting) due to death of specific cells in the side of the organ. Another type of cell death occurred in the formation of lysigenous aerenchyma. Senescence of the coleoptile was also noted, during which discolouration of the chlorophyll and tissue browning were apparent. DNA fragmentation was observed by deoxynucleotidyltransferase-mediated dUTP nick end labelling (TUNEL) assay, and further confirmed by the appearance of oligonucleosomal DNA ladders in senescent coleoptile cells. Two nucleases (Nuc-a and Nuc-b) were detected by in-gel-assay from proteins isolated from coleoptiles. Nuc-a, commonly observed in three cell death phases required either Ca2+ or Mg2+, whereas Nuc-b which appeared during senescence required both Ca2+ and Mg2+. Both nucleases were strongly inhibited by Zn2+. (C) 2000 Annals of Botany Company.
  英語
  DOI：https://doi.org/10.1006/anbo.2000.1199
  DOI ID：10.1006/anbo.2000.1199, ISSN：0305-7364, SCOPUS ID：0033832231
• Ion beam as a noble tool to induce apoptosis-like cell death in roots of maize (Zea mays L.)　　　　　　　　　　　　　　　
  Maki Kawai; Yasuhiko Kobayashi; Aiko Hirata; Yutaka Oono; Hiroshi Watanabe; Hirofumi Uchimiya
  巻：17, 号：4, 開始ページ：305, 終了ページ：308, 2000年
  Maize seedlings were irradiated with 20Ne8+ generated by the AVF cyclotron. The growth suppression at the different dosages of ion beam was observed in both root and coleoptile. DNA laddering was also observed at the dosage over 100 Gy. In addition, abnormal morphological changes including chromatin condensation, typical of apoptosis in animal cells, were noted by light and electron microscopy. Our results indicate that the ion beam can serve as an effective tool to induce apoptosis-like cell death in plant cells.
  DOI：https://doi.org/10.5511/plantbiotechnology.17.305
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0000853046&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0000853046&origin=inward
  DOI ID：10.5511/plantbiotechnology.17.305, ISSN：1342-4580, eISSN：1347-6114, CiNii Articles ID：10010147080, SCOPUS ID：0000853046
• Transverse vein differentiation associated with gas space formation - Fate of the middle cell layer in leaf sheath development of rice　　　　　　　　　　　　　　　
  C Matsukura; M Kawai; K Toyofuku; RA Barrero; H Uchimiya; J Yamaguchi
  巻：85, 号：1, 開始ページ：19, 終了ページ：27, 2000年01月
  In monocotyledons, the leaf vascular network consists of a hierarchical sequence of vertical vascular bundles and numerous transverse veins that interconnect adjacent vertical veins. In the leaf sheath of these species, especially grasses, lysigenous gas cavities (gas spaces) are developed into intervascular spaces and provide a gas conducting system to non-aerial Darts under flooded conditions. The spatial relationship between gas space formation and transverse vein differentiation was investigated using the leaf sheath of rice (Oryza sativa L.). Histochemical observation showed that patterns of differentiation of the transverse vein are distinct from those of vertical vascular bundles. On the other hand, gas spaces are formed through the processes of cell death (collapse). Both events are initiated at a specific cell position in the middle layers of the leaf sheath, from which the vascular system of the leaf is derived; this indicates that differentiation of transverse veins is associated with gas space formation. The cell-to-cell movement of fluorescein isothiocyanate-conjugated dextran injected into middle layer cells coincided with the area where cell collapse occurred, indicating a close relationship between the middle and adaxial cell layers, but not abaxial cell layers. A uniform cell number between each transverse vein in the leaf sheath suggested the involvement of spatial regulation in transverse vein formation regardless of clonal history at the later stage of leaf vein canalization. (C) 2000 Annals of Botany Company.
  英語
  DOI：https://doi.org/10.1006/anbo.1999.0993
  DOI ID：10.1006/anbo.1999.0993, ISSN：0305-7364, Web of Science ID：WOS:000084991000004
• Evolutionally conserved plant homologue of the Bax Inhibitor-1 (BI-1) gene capable of suppressing Bax-induced cell death in yeast　　　　　　　　　　　　　　　
  M Kawai; L Pan; JC Reed; H Uchimiya
  巻：464, 号：3, 開始ページ：143, 終了ページ：147, 1999年12月
  The plant homologue of Bax Inhibitor-1, a gene described to suppress the cell death induced by Bax gene expression in yeast, was isolated from Oryza sativa L. (rice) and Arabidopsis. The amino acid sequence of the predicted protein was well conserved in both animal and plant (45% in amino acids) and contained six or seven membrane-spanning segments. Northern blot analysis showed that OsBI-1 transcripts were present in all tissues examined. The OsBI-1 cDNA suppressed cell death induced by mammalian Bax in yeast, suggesting functional conservation of this BI-I homologue in the plant kingdom. (C) 1999 Federation of European Biochemical Societies.
  英語
  DOI：https://doi.org/10.1016/S0014-5793(99)01695-6
  DOI ID：10.1016/S0014-5793(99)01695-6, ISSN：0014-5793, CiNii Articles ID：80011426952, PubMed ID：10618494, Web of Science ID：WOS:000084654800009
• TRANSVERSE VEIN DIFFERENTIATION ASSOCIATED WITH THE AIR SPACE FORMATION - CELL FATE OF MIDDLE LAYER IN LEAF SHEATH DEVELOPMENT OF RICE -　　　　　　　　　　　　　　　
  MATSUKURA Chiaki; KAWAI Maki; TOYOFUKU Kyoko; BARRERO Robert A.; UCHIMIYA Hirofumi; YAMAGUCHI Junji
  Plant and cell physiology, 巻：40, 開始ページ：s15, 終了ページ：s15, 1999年03月
  英語
  ISSN：0032-0781, CiNii Articles ID：10003757764, CiNii Books ID：AA0077511X
• Morphological analysis of apoptosis-like cell death induced by ion beam irradiation in plant cells　　　　　　　　　　　　　　　
  JAERI report 1999, 開始ページ：54, 終了ページ：55, 1999年
• Cortical cell death, cell proliferation, macromolecular movements and rTip1 expression pattern in roots of rice (Oryza sativa L,) under NaCl stress　　　　　　　　　　　　　　　
  PK Samarajeewa; RA Barrero; C Umeda-Hara; M Kawai; H Uchimiya
  巻：207, 号：3, 開始ページ：354, 終了ページ：361, 1999年01月
  The mode of action of NaCl in terms of cell proliferation and cell death was examined in seminal roots of rice plants (Oryza sativa L.). Salt/sodium chloride was inhibitory to cell number increase and to cell death in cortical tissue, whereas final cortical cell size was the same as in control roots that were not exposed to NaCl. It seems that NaCl may stimulate the transition phase from cell division to cell elongation. Further analysis of the role of NaCl in the suppression of cortical cell death was confined to a delay in the early stage of cell collapse, which was caused by tonoplast disruption, and plasma-membrane destruction. Sodium chloride did not have any effect on the cell-to-cell movement of macromolecules in the root cortex. In-situ hybridization studies indicated that expression of the gene for tonoplast intrinsic protein (rTip1) was localized predominantly in the epidermal and exodermal cells as well as in metaxylem cells in seminal roots. Upon NaCl treatment, the intensity of rTip1 gene expression was raised in the cortical parenchyma, suggesting that salt plays a role in the rapid onset of cell elongation.
  英語
  DOI：https://doi.org/10.1007/s004250050492
  DOI ID：10.1007/s004250050492, ISSN：0032-0935, Web of Science ID：WOS:000078274900004
• Morphological analysis of apoptosis-like cell death induced by ion beam irradiation in plant cells　　　　　　　　　　　　　　　
  開始ページ：54, 終了ページ：55, 1999年
• Isolation of a cotton CAP gene: a homologue of adenylyl cyclase-associated protein highly expressed during fiber elongation　　　　　　　　　　　　　　　
  M Kawai; S Aotsuka; H Uchimiya
  巻：39, 号：12, 開始ページ：1380, 終了ページ：1383, 1998年12月
  The cDNA encoding CAP (adenylyl cyclase-associated protein) was isolated from a cotton (Gossypium hirsutum) fiber cDNA library. The cDNA (GhCAP) contained an open reading frame that encoded 471 amino acid residues. RNA blot analysis showed that the cotton CAP gene was expressed mainly in young fibers.
  英語
  ISSN：0032-0781, Web of Science ID：WOS:000077761600019
• Stimulation of adenylate kinase in rice seedlings under submergence stress　　　　　　　　　　　　　　　
  M Kawai; M Umeda; H Uchimiya
  巻：152, 号：4-5, 開始ページ：533, 終了ページ：539, 1998年05月
  The enzymatic activity of adenylate kinase was stimulated in submerged rice seedlings. This activity was enhanced in every organ of the submerged plants. Treatment with N-2 gas had the same effect as submergence, a result which suggests that O-2-depletion is a major cause of the stimulation of adenylate kinase activity. Northern blot analysis also indicated accumulation of adenylate kinase mRNA under submerged condition. Furthermore, different induction patterns of enzymatic activity were seen in two rice varieties, FR13A and IR42, which are respectively tolerant and intolerant of complete submergence.
  英語
  ISSN：0176-1617, Web of Science ID：WOS:000073921400029
• Cellular dissection of the degradation pattern of cortical cell death during aerenchyma formation of rice roots　　　　　　　　　　　　　　　
  M Kawai; PK Samarajeewa; RA Barrero; M Nishiguchi; H Uchimiya
  巻：204, 号：3, 開始ページ：277, 終了ページ：287, 1998年03月
  Cellular events which occur prior to cell collapse were examined in the root cortex of rice (Oryza sativa L.) during aerenchyma formation. Cell collapse started at a specific position in the mid cortex. These cells were distinct in shape from those located towards the periphery. Furthermore, cell collapse was preceded by acidification and the loss of plasma-membrane integrity in cells of the mid cortex. Subsequent death of neighboring cells followed a radial path. Microinjection of molecules of different sizes conjugated with fluorescein isothiocyanate (FITC) showed a molecular exclusion limit of between 9.3 and 19.6 kDa in the root cortex. Furthermore, large molecules, i.e. those around 9.3 kDa, were predominantly transferred in a radial direction, which coincided with the path of sequential cell death.
  英語
  DOI：https://doi.org/10.1007/s004250050257
  DOI ID：10.1007/s004250050257, ISSN：0032-0935, CiNii Articles ID：10009945397, Web of Science ID：WOS:000072453800002
• Induction of apoptosis in plant cells by ion beam irradiation　　　　　　　　　　　　　　　
  JAERI report 1998, 開始ページ：57, 1998年
• Induction of apoptosis in plant cells by ion beam irradiation　　　　　　　　　　　　　　　
  開始ページ：57, 1998年
• Genetic engineering for abiotic stress tolerance in plants　　　　　　　　　　　　　　　
  Harcharan S. Dhariwal; Maki Kawai; Hirofumi Uchimiya
  巻：15, 号：1, 開始ページ：1, 終了ページ：10, 1998年
  Development of plant varieties with a high level of tolerance to abiotic stresses is crucial for establishing full yield potential and to stabilize production. Due to the multitude of abiotic stresses and their complex genetic control the progress of breeding for tolerance to abiotic stresses using conventional approaches has not been very rewarding. Recent advances in cellular and molecular biology have made it possible to clone important genes and mobilize them in any organism across barriers of sexual hybridization for stable expression and transmission. All living organisms have evolved mechanisms for avoidance and/or tolerance to one or more of the abiotic stresses. Plants producing crucial enzymes or proteins from various organisms involved in abiotic stress tolerance mechanisms have shown significant advantage over their wild type controls under stressed environment. The enhanced level of compatible osmolytes, radical scavengers and other transgene products correlated with the degree of tolerance. Further understanding of the molecular mechanisms of stress perception, signal transduction and response by plants and other organisms may help to engineer plants with high levels of tolerance to multiple stresses. Perspectives and additional approaches for further improving the tolerance to abiotic stresses through genetic engineering are discussed.
  英語, 書評論文,書評,文献紹介等
  DOI：https://doi.org/10.5511/plantbiotechnology.15.1
  DOI ID：10.5511/plantbiotechnology.15.1, ISSN：1347-6114, CiNii Articles ID：10006290826, SCOPUS ID：54649083917
• ANALYSIS OF AERENCHYMA FORMATION CAUSED BY CELL DEATH IN RICE ROOT　　　　　　　　　　　　　　　
  KAWAI Maki; SAMARAJEEWA P. K.; YAMAGUCHI Masatoshi; UCHIMIYA Hirofumi
  Plant and cell physiology, 巻：37, 開始ページ：131, 終了ページ：131, 1996年03月
  英語
  ISSN：0032-0781, CiNii Articles ID：10002708306, CiNii Books ID：AA0077511X
• TISSUE-SPECIFIC LOCALIZATION OF ADENYLATE KINASE IN RICE (ORYZA-SATIVA L) PLANTS　　　　　　　　　　　　　　　
  M KAWAI; H UCHIMIYA
  巻：146, 号：3, 開始ページ：239, 終了ページ：242, 1995年06月
  Anti-adenylate kinase (AK) antibody was used to locate AK protein in organs and tissues of rice plants. This antibody reacted with a 27-kDa protein in callus, root, and leaf tissues. Tissue-printing immunoblot analysis revealed that AK proteins were expressed intensively in vascular tissues.
  英語
  ISSN：0176-1617, Web of Science ID：WOS:A1995RJ37600008
• BIOCHEMICAL-PROPERTIES OF RICE ADENYLATE KINASE AND SUBCELLULAR LOCATION IN PLANT-CELLS　　　　　　　　　　　　　　　
  M KAWAI; H UCHIMIYA
  巻：27, 号：5, 開始ページ：943, 終了ページ：951, 1995年03月
  Previously, we characterized nucleotide sequences of two cDNAs encoding adenylate kinase from rice plants (Oryza sativa L.). Each cDNA (Adk-a or Adk-b) was cloned into the expression vector pET 11d-GST to produce GST-AK fusion proteins in Escherichia coli. Recombinant proteins were cleaved by thrombin, and GST-free adenylate kinase proteins were obtained. Enzyme activity profiles of different pH and inhibition effects to the enzyme by Ap5A (adenosine-5'-pentaphospho-5'-adenosine) indicates that both adenylate kinase proteins have similar biochemical characteristics. Among the nucleoside monophosphates (AMP, CMP, GMP and UMP) investigated, only AMP reacted with ATP. Furthermore, using the antiserum against the rice adenylate kinase proteins, the cellular location of adenylate kinase proteins was examined by immunomicroscopic analysis in combination with a subcellular fractionation method. The results indicated that adenylate kinase proteins were distributed largely in cytosol of rice cells.
  英語
  ISSN：0167-4412, Web of Science ID：WOS:A1995RB39500009
• Sodium Chloride Stimulates Adenylate Kinase Level in Seedlings of Salt-Sensitive Rice Varieties　　　　　　　　　　　　　　　
  Pallepitiya K. Samarajeewa; Maki Kawai; Toyoaki Anai; Atsushi Hirai; Hirofumi Uchimiya
  巻：147, 号：2, 開始ページ：277, 終了ページ：280, 1995年
  Comparison of adenylate kinase activities in rice seedlings (Oryza sativa L. cv. Yamahoushi) that had been grown in the absence or presence of NaCl indicated that NaCI apparently stimulated enzyme activities in roots of this salt-sensitive japonica rice cultivar. Such stimulation of enzyme activities is not limited to a specific portion of root tissues. Furthermore, NaCl-induced adenylate kinase activation was confirmed in the indica rice cultivar IR 28 susceptible to salinity-stress, but not in the NaCl-tolerant indica cultivar Nona Bokra. Thus in salt sensitive rice plants, adenylate kinase may play some role in the adenylate homeostatis at the early stages of rice seedling growth subjected to salt-stress. © 1995, Gustav Fischer Verlag, Stuttgart. All rights reserved.
  英語
  DOI：https://doi.org/10.1016/S0176-1617(11)81519-1
  DOI ID：10.1016/S0176-1617(11)81519-1, ISSN：0176-1617, SCOPUS ID：0029190285
• Tissus specific localization of adenylate kinase in rice(Oryza sativa L.) plants　　　　　　　　　　　　　　　
  巻：146, 開始ページ：239, 終了ページ：243, 1995年
• Molecular characterization of cDNAencoing for adenylate kinase of rice(Oryza sative L.)　　　　　　　　　　　　　　　
  Plant J., 巻：2, 開始ページ：845, 終了ページ：854, 1992年
• Molecular characterization of cDNAencoing for adenylate kinase of rice(Oryza sative L.)　　　　　　　　　　　　　　　
  巻：2, 開始ページ：845, 終了ページ：854, 1992年

• 日本分子生物学会
• 日本植物細胞分子生物学会
• 日本植物学会
• 日本植物生理学会

• 光合成の多様性を支える電子受容体NADP供給系の変容　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 学術変革領域研究(A), 2024年04月01日 - 2026年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：7410000, 配分額（直接経費）：5700000, 配分額（間接経費）：1710000
  課題番号：24H02065
• 植物環境応答におけるNAD(P)(H)代謝ネットワーク制御の分子基盤　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2022年04月01日 - 2026年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：17160000, 配分額（直接経費）：13200000, 配分額（間接経費）：3960000
  ピリジンヌクレオチドNAD(P)(H)は、全ての生物が細胞内酸化還元反応に用いる電子伝達物質である。呼吸や光合成、脂質代謝などで使用されるのみならず、NADPHは環境ストレスによって細胞内に生じる活性酸素種の消去系においても中心的な役割を担う。このため、NAD(P)(H)の量やバランスの変化は植物の生長のみならず、環境応答や収量に大きく影響を及ぼす。しかしながらこれらがどのように量的に制御されているのかは解明されていない。本研究では、植物におけるNAD(P)(H)の細胞内バランス制御の分子機構を解明することを目的としている。前年度に引き続き、シロイヌナズナの葉緑体局在性NADリン酸化酵素(NADK2)の活性制御の分子機構に焦点を当て研究に取り組んだ。
  NADK2を欠損したシロイヌナズナ変異体(nadk2)は、恒光条件では葉の色が黄緑になり生育遅延を示すが生育が可能であるのに対し、短日条件では著しい生育阻害を示す。葉緑体局在性のNADK2は、他の細胞内局在を示すNADKには存在しない長いN末領域を有している。この領域内にシロイヌナズナが明暗状態で生育するために重要な役割を担うドメインが存在する可能性があると考え研究を実施した。さまざまな生物の葉緑体局在あるいは光合成機能に関与すると考えられるNADK分子種の配列比較から、NADKの酵素活性に直接関与すると考えられるNADKモチーフに加えて長いN領域を持つようになったのは、進化的にコケやシダ植物以降であり、クラミドモナスやシアノバクテリアにはそのような配列は存在しなかった。また、N領域内のカルモジュリン結合部位やシステイン残基に注目して比較を行った結果、植物の多細胞化や陸上化に伴い、N領域が発達した可能性が新たに考えられた。
  課題番号：23K23564
• 植物環境応答におけるNAD(P)(H)代謝ネットワーク制御の分子基盤　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2022年04月01日 - 2026年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：17160000, 配分額（直接経費）：13200000, 配分額（間接経費）：3960000
  課題番号：22H02298
• 酸化還元バランス制御を介した不均一環境への応答機構　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 学術変革領域研究(A), 2023年04月01日 - 2025年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：7800000, 配分額（直接経費）：6000000, 配分額（間接経費）：1800000
  自然環境下で植物は、様々に変動する環境条件に応答して細胞内代謝の切り換えを行っていると考えられる。ニコチンアミドアデニンジヌクレオチドNAD(P)(H)は全ての生物が生体内の酸化還元反応に用いる電子伝達物質であり、その量やバランスの変化は光合成や呼吸・活性酸素消去系などを介して植物の生育に大きな影響をもたらす。本研究では、不均一環境下におけるNAD(P)(H)バランス制御のメカニズムを解明し、植物の成長と物質生産を統御するレジリエンス機構を明らかにすることを目的としている。
  シロイヌナズナにおいて、複数の転写開始点制御を受け、4種類の長さの異なる翻訳産物を生じる因子としてカルモジュリン/カルシウム依存的なNADキナーゼ活性を見出した。本因子は、これまで知られているNADKに保存されたNADKモチーフを持たないという特徴がある。当該年度は、４種類の翻訳産物(NADKc.1-NADKc.4)の細胞内局在解析を中心に行った。GFPとの融合タンパク質としてシロイヌナズナで発現させ、共焦点レーザー顕微鏡観察を行った結果、最も長いNADKc.1はミトコンドリアをはじめとして葉緑体膜や葉緑体内にも局在するマルチターゲティング性を示した。一方、NADKc.2とNADKc.3はサイトゾル局在であることが示されたが、NADKc.4についてはGFPのシグナルを検出することができなかったため、タンパク質として不安定である可能性が考えられた。また大腸菌を用いてリコンビナントタンパク質を発現・精製した結果、NADKc.1とNADKc.2のみがカルモジュリン/カルシウム依存的な活性を示した。これらの結果は、4種類の転写産物が細胞内でそれぞれ異なった生理機能を有している可能性を示している。
  課題番号：23H04187
• 植物の不均一環境変動応答を支える細胞内酸化還元力バランス制御　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 学術変革領域研究(A), 2021年09月10日 - 2023年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：9360000, 配分額（直接経費）：7200000, 配分額（間接経費）：2160000
  課題番号：21H05647
• 葉緑体機能を支えるレドックス制御システムの包括的解析　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2019年04月01日 - 2023年03月31日
  吉田 啓亮; 増田 建; 川合 真紀, 東京工業大学
  配分額（総額）：17160000, 配分額（直接経費）：13200000, 配分額（間接経費）：3960000
  移動能力を欠く植物が、絶えず変動する光環境で効率よく光合成を行うためには、光合成の場である葉緑体の機能を柔軟かつ精密に制御する必要がある。本研究では、酸化還元を基盤としたタンパク質の翻訳後制御であるレドックス制御に注目する。近年、葉緑体のレドックス制御系は、多くのタンパク質（制御因子群と標的群）が関わるネットワーク上システムとして再認識されており、そのシステム全体の分子基盤や生理意義の解明が重要な課題となっている。本研究課題では、分子生物学・生化学から生理生態学までを貫徹する基礎研究を行い、葉緑体機能を統御するレドックス制御系を包括的に理解する。
  当該年度は、レドックス制御系の主要経路と考えられているフェレドキシン／チオレドキシン経路の生理機能の解析を重点的に実施した。前年度に、この経路の中心的ハブとして働くFTRの完全破壊株をCRISPR/Cas9によって作出していたので、この変異株を本年度の実験に用いた。タンパク質の酸化還元応答を調べたところ、野生株においては葉緑体ストロマ局在のタンパク質群が光に依存してダイナミックな還元応答を示した一方、FTR変異株においてはまったくそれが観測されなかった。FTR変異株では、著しい生育阻害、光合成速度の減少、葉緑体の形態異常が見られた。これらの結果から、フェレドキシン／チオレドキシンは光照射に応じてストロマタンパク質を活性化させるために必要な唯一の経路であり、光合成に決定的な役割を果たしていることが明らかになった。また本研究では、ATP合成酵素の還元・活性化に関わる未知の還元力伝達経路の存在が示唆された（論文投稿中）。
  課題番号：19H03241
• 植物免疫解明に向けたマイクロドメイン可視化プローブの開発　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 挑戦的研究(萌芽), 2018年06月29日 - 2022年03月31日
  川合 真紀; 長野 稔, 埼玉大学
  配分額（総額）：6370000, 配分額（直接経費）：4900000, 配分額（間接経費）：1470000
  植物の病害応答に重要な役割を果たす、細胞膜上に点在するマイクロドメインの機能解明のため、その主要構成脂質をターゲットとした植物マイクロドメイン可視化プローブの開発を行った。植物ステロールに結合する可視化プローブGFP-D4Lを開発し、細胞膜上のマイクロドメイン構造の可視化に成功した。恒常的にGFP-D4Lを発現するシロイヌナズナ系統の作出も行い、病害応答時にマイクロドメインが特定の動態を示すことを明らかにした。
  課題番号：18K19164
• 植物の環境ストレス応答における生体膜マイクロドメインの構築と機能　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2018年04月01日 - 2022年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：17290000, 配分額（直接経費）：13300000, 配分額（間接経費）：3990000
  植物スフィンゴ脂質のセラミド骨格に不飽和結合を導入する２つの酵素、SLD1およびADS2は、ともに、植物の低温耐性に寄与することがこれまでに明らかとなりつつある。SLDは長鎖塩基（long-chain base、LCB）のΔ8位の不飽和化酵素であり、ADSは脂肪酸n-9位の不飽和化に関与する酵素である。引き続き両者の二重変異体の解析を引き続き行った結果、sld1ads2は単独変異体よりも低温耐性がさらに顕著に低下し、低温応答時に見られるアントシアニンの蓄積量も単独変異体よりもさらに減少していた。遺伝子発現解析の結果、アントシアニン合成にかかわる酵素をコードする遺伝子の発現が低下し、これらをさらに上流で支配するHY5の発現も異常になっていた。これらの結果から、sld1ads2では細胞膜での温度感知の仕組みに異常が生じている可能性が示された。また、スフィンゴ脂質の親水基部の機能に関する研究においては、糖鎖構造と生理機能に関する研究を進めた。スフィンゴ脂質GIPCは、親水部としてリン酸イノシトールと複数の糖が結合し、糖鎖部分は多様性をもつ。シロイヌナズナで、末端にHexを転移する酵素GMT1が同定されている。その欠損変異体gmt1では野生型に比べて生育が著しく抑制され、細胞内にサリチル酸(SA)が蓄積していることをこれまでに示した。そこで、sld1ads2変異体にSA分解酵素を発現させた系統を作出して調べた結果、生育異常はかなり改善されたが、効果は部分的であることから、SAの蓄積以外の原因により生育阻害が起きていることが示された。また、GIPCの末端にHexNを転移する酵素GINTをgmt1変異体で発現させた系統で個々の表現型を評価し、それぞれの糖鎖構造の機能の違いについて考察をおこなった。
  課題番号：18H02165
• 葉緑体NADP供給とプロトン駆動力のバランス制御機構の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 新学術領域研究(研究領域提案型), 2019年04月01日 - 2021年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：7540000, 配分額（直接経費）：5800000, 配分額（間接経費）：1740000
  本研究は葉緑体NADP+供給とプロトン駆動力のバランス制御機構の解明を目的として、I. CETとNADP+合成の交互作用、および、II. 光合成電子伝達経路によるNADK2活性制御機構、の２点の研究を実施した。項目Iでは、前年度までに変異体および薬剤を使用した実験によって、CET活性の低下に伴って葉緑体NADP+量が低下する事をin vivoで明らかにしており、本年度は葉緑体NADP+量が低下した時のCET活性をin vivoで計測した。葉緑体NADP+量を暗馴化時間によって調節した後に、速やかにCET活性を計測することによって、葉緑体NADP+量の低下に伴ってCET活性が増大するという明確な相関を見出した。従って、葉緑体NADP+量の変動が光合成電子伝達フローの切り替えに関与しており、光条件に応じて需給変動が生じるLET活性変化は葉緑体NADP+の変動による調節を受けており、CET活性が葉緑体NADP+量を制御する一連の流れが示唆された。
  また、項目II.では光合成電子伝達鎖にNADP+を供給するNADK2活性制御機構について、タンパク質のN末領域内に暗所で酵素活性を抑制する機能が存在することを示した。また、nadk2欠損変異体の表現型を回復させる変異体をスクリーニングした結果、葉緑体内に存在すると考えられる機能未知のタンパク質が失われることで、nadk2の表現型が軽減されることが明らかとなり、葉緑体内のNADP+供給の制御機構の一端を解明することができた。
  課題番号：19H04715
• プロトン駆動力とNADP量的制御のクロストーク　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 新学術領域研究(研究領域提案型), 2017年04月01日 - 2019年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：8320000, 配分額（直接経費）：6400000, 配分額（間接経費）：1920000
  葉緑体の光化学系において、NADPHは光で駆動されるリニア電子伝達の最終電子受容体NADP+の還元によって生成し、ATPは電子伝達で形成したプロトン勾配を利用して合成される。電子伝達量は、電子を受容可能なNADPプールサイズ（NADP+とNADPHの総和）によって制限される一方で、NADキナーゼ（NADK）によるNADP+合成にはATPが必要である。すなわち、NADP+量によってATP合成が制限され、ATP量によってNADP+合成が制限されるという交互作用（クロストーク）の存在が推定されるが、これまでNADPプールサイズをプロトン駆動力の制御要因として着目した研究例はない。本研究は、NADPプールサイズがプロトン駆動力に及ぼす影響と、プロトン駆動力を形成する電子伝達経路がNADK活性に及ぼす影響を解明することを目的として実施した。はじめに、葉緑体NADPプールサイズが変動する光に応答して増減を繰り返す現象を見出した。さらに、葉緑体型NADK酵素（NADK2）の活性化と基質NAD+の供給が葉緑体NADP プールサイズの律速となることを明らかにした。ここから、光照射とNAD+前駆体処理を組み合わせることでNADPプールサイズを制御する手法を構築し、NADPプールサイズの変動に応答してプロトン駆動力が変化することを明らかにした。また、NADP恒常性変異体の解析から葉緑体レドックス制御ネットワークのうちフェレドキシン(Fd)-チオレドキシンm（Trx-m）経路によってNADK2活性が抑制的に制御されることを明らかにした。今後、これらの知見と合わせて光依存的にNADK2活性を促進的に制御する経路について解析を進めることで、変動環境下において電子受容体であるNADPプールサイズを調節して光合成活性を最適化して環境に順応する機構が解明されることが期待される。
  課題番号：17H05714
• 細胞膜マイクロドメインを介した植物環境ストレス応答機構の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2014年04月01日 - 2019年03月31日
  川合 真紀, 埼玉大学
  配分額（総額）：17160000, 配分額（直接経費）：13200000, 配分額（間接経費）：3960000
  植物は外的なストレスに対して、細胞膜上のマイクロドメインを介してシグナル伝達を行い、様々な応答反応を行なっていると考えられる。本研究では、高発現すると酸化ストレス耐性を植物細胞に付与するBI-1遺伝子の解析に端を発し、小胞体膜上のスフィンゴ脂質生合成関連酵素群を介した細胞応答機構の解明を行った。BI-1の相互作用因子として単離されたFAH、ELO、SLDに注目し、これらのBI-1との結合性の確認を行った。また、個々の遺伝子の発現量を変化させたイネおよびシロイヌナズナを作出し、それらの系統で、実際に細胞膜上のマイクロドメインを構成するスフィンゴ脂質の組成が変化する事を明らかにした。
  課題番号：26292190
• 施設園芸における地球温暖化効果ガス排出動態の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2010年 - 2012年
  吉原 利一; 橋田 慎之介; 後藤 文之; 庄子 和博; 植本 弘明; 淨閑 正史; 川合 真紀
  配分額（総額）：19370000, 配分額（直接経費）：14900000, 配分額（間接経費）：4470000
  トマトのロックウール栽培をモデルケースとして、(1)栽培に伴って発生するGHG(CO_2、N_2O、CH_4)が気温や施肥量などの環境要因や、植物体の生育状況に強く依存すること、(2)ロックウール栽培と土耕栽培におけるGHG 発生パターンには大きな差異は認められないが、発生量は土耕の方が大きいこと、(3)N_2O の発生に関わる微生物は、種類・量ともに発生量とほとんど相関がないこと、などを明らかにした。また、特に(4)センサーによるN_2O のリアルタイム測定法を確立したことによって、N_2O の消長が施肥と極めて正確に同調しており、施肥開始後、増加を示すまでの時間は約10 分程度、ピークに至るまでに30 分から1 時間程度、施肥をやめてから基底状態に戻るまでに約3～7時間程度と極めて、早い反応であることなどが明らかとなった。
  課題番号：22380139
• 脂肪酸代謝をエフェクターとする植物酸化ストレス応答細胞死の機構　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 新学術領域研究(研究領域提案型), 2009年 - 2010年
  川合 真紀, 埼玉大学
  配分額（総額）：6110000, 配分額（直接経費）：4700000, 配分額（間接経費）：1410000
  植物が受ける環境ストレスの多くは光合成電子伝達系を阻害し、植物細胞内に活性酸素種を発生させ、酸化ストレスをもたらす。本研究では、生物界に保存された酸化ストレス誘導性細胞死の抑制因子として、Bax Inhibitor-1(BI-1)に注目し、BI-1による酸化ストレス耐性獲得機構の分子メカニズムを明らかにすることを目的として研究をおこなった。
  小胞体膜上に局在するBI-1の相互作用因子として単離されたスフィンゴ脂質ヒドロキシル化酵素(FAH)の解析に加え、脂肪酸伸長酵素(ELO)との相互作用に関する解析を進めた。シロイヌナズナには4種類のELO(ELO1-4)が存在する。酵母を用いた2-hybrid法、植物細胞を用いたBiFC法により、このうち、ELO1及びELO2がCb5と相互作用することが示され、一方、ELO3及びELO4については相互作用を示さないことが明らかとなった。小胞体膜上にFAHを含めたこれらの因子が集合体として存在する可能性が考えられた。また、これらの脂質代謝酵素の産物は特にスフィンゴ脂質に含まれる事が知られている。BI-1を高発現させたイネの培養細胞はメナジオンなどの酸化ストレス薬剤に対する耐性を獲得する。この細胞より細胞膜を単離し、さらに界面活性剤に耐性を示すマイクロドメインを精製し、膜組成の解析を行った。その結果、BI-1を高発現する綱胞では2-ヒドロキシ脂肪酸量が増加していることが確認された。さらにこのマイクロドメインに存在するタンパク質のプロテオーム解析を行った結果、複数のタンパク質の量が変化していることが明らかとなった。今後、これらの機能を明らかにすることによって植物の酸化ストレス応答を分子レベルで解明できると期待される。
  課題番号：21117505
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