2005 Fiscal Year Final Research Report Summary
Development of Assay Method of Singlet Excited Oxygen in Chloroplasts and Molecular Mechanisms of Its Generation, Scavenging and Action
| Project/Area Number |
15370026
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物生理・分子
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| Research Institution | Fukuyama University |
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Principal Investigator |
ASADA Kozi Fukuyama University, Department of Life Science and Biotechnology, 生命工学部, 教授 (50027182)
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| Co-Investigator(Kenkyū-buntansha) |
HIDES Eva Institute for Plant Biology, Hungary, Chief Faculty Member
KOS Peter Institute for Plant Biology, Hungary, Faculty Member
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| Project Period (FY) |
2003 – 2005
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| Keywords | Singlet oxygen molecule / Reactive oxygen species / Chloroplasts / Plant photosynthesis / Scavenging of reactive oxygen species / Action of reactive species of oxygen / Cyclic electron transport / Photon excess stress |
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| Research Abstract |
Sun light intensity (P) is very variable under natural conditions, not only by diurnal change but also by meteorological factors. When P is higher than those required for CO_2-assimilation (A), excess photons produce reactive oxygen species (ROS) and the ROS inactivates chloroplasts(photoinhibition). To adapt such photon excess stress chloroplasts would equip the relaxation system to suppress the ROS production and the scavenging system of ROS. In this research project, establishment of the detection and assay of singlet oxygen (^1O_2) is the primary object. Because its life time is very short (10 μs ), we used thylakoid membrane-associable fluorescence probes (DPAX and DanePy) and the pulse-amplitude modulation system for its low photodecomposition of the probes and the assay of the fluorescence change of the probes under actinic light illumination.
The established method allows to determine at real time the generation of ^1O_2 in thylakoids. Thylakoids generates ^1O_2 immediately after the actinic light illumination indicating that this species of ROS is photoproduced without specific photoinhibition of thylakoids. Further, ^1O_2 generation is increased by 5-6 folds under anaerobic conditions where no electron acceptor for thylakoids is available. In other words, this finding indicates that the electron transfer to oxygen (water-water cycle) suppresses the generation of ^1O_2 in PSII and the ^1O_2-induced photoinhibition. In addition, the relaxation systems to escape from P>A stress have been revealed for the participating enzymes in the cyclic electron flow through PSI and its maintenance by ascorbate, the function of and participating enzymes in the water-water cycle.
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Research Products
(24 results)
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[Journal Article] Purification and cDNA cloning of chloroplastic Monodehydroascorbate radical reductase from spinach2005
Author(s)
S.Sano, S.Tao, Y.Endo, T.Inaba, MA.Hossain, C.Miyake, M.Matsuo, M.Matsuo, H.Aoki, K.Asada, K.Saito
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Journal Title
Bioscience, Biotechnology and Biochemistry 69
Pages: 762-772
Description
「研究成果報告書概要(和文)」より
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[Journal Article] Purification and cDNA cloning of chloroplastic Monodehydroascorbate radical reductase from spinach2005
Author(s)
S.Sano, S.Tao, Y.Endo, T.Inaba, MA.Hossain, C.Miyake, M.Matsuop, H.Aoki, K.Asada, K.Saito
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Journal Title
Bioscience, Biotechnology and Biochemistry 69
Pages: 762-772
Description
「研究成果報告書概要(欧文)」より
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