| Project/Area Number |
02044084
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Kyoto University |
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Principal Investigator |
ASADA Kozi Professor, Research Institute for Food Science, Kyoto Universit, 食糧科学研究所, 教授 (50027182)
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| Co-Investigator(Kenkyū-buntansha) |
HEBER Ulrich Professor, Lehlstuhl der Botanik Universitat Wurzburg, Lehrstuhl dor Botan, Professor
SCHREIBER Ulrich Professor, Lehlstuhl der Botanik Universitat Wurzburg, Lehrstuhl dor Botan, Professor
MANO Junichi Instructor. Research Institute for Food Science, Kyoto University, 食糧科学研究所, 助手 (50243100)
ENDO Tsuyoshi Instructor. Research Institute for Food Science, Kyoto University, 食糧科学研究所, 助手 (90201962)
SHREIBER Ulr Universitat Wurzburg, Lehrstuhl der Botan, Professor
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| Project Period (FY) |
1990 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥8,400,000 (Direct Cost: ¥8,400,000)
Fiscal Year 1992: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1991: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1990: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Synechococcus 7002 / Synechocystis 6803 / Maize / Cyclic Electron transport / Chlorophyll Fluorescence / P700 / C4 Piants / NAD(P)H Dehydrogenase / アスコルビン酸ペルオキシダ-ゼ / 酸素吸収 / プラストキノン / 陽葉植物 / 陰葉植物 / 過酸化水素 |
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| Research Abstract |
1. Cyclic electron flow in cyanobacteria : Synechocystis PCC 6803 (WT)showed a low oxidation level of P700, but its NAD(P)H dehydrogenase-defective mutant showed a complete oxidation of P700, under a far-red light (FR), suggesting that electrons from respiratory substrates reduce P700^+ Via photosynthetic intersystem chain mediated by NAD(P)H dehydrogenase. The reduction of P700^+ after illumination of FR was mostly accounted for the electron flow from respiratory donors (t_<1/2> = 0.3 s), whereas, that after a 50-ms, saturating pulse light in the presence of DCMU by flow from the NAD(P)H photoproduced by PSI (t_<1/2>= 72 ms). This was inhibited also in the mutant cells. Thus NAD(P)H dehydyrogenase appears to be the site of main entry into the intersystem chain for the NAD(P)H-mediated cyclic flow as well as for the respiratory flow.
2. Cyclic electron flow in C4 plants : The pool size of electrons from the stroma that were donated to P700^+ and stored during actinic illumination was estimated in C3 and C4 plants by the time courses of re-oxidation of P700 by far-red light after actinic illumination and after50-ms pulse light. C4 electrons from stroma was further sustained by the rise of chlorophyll fluorescence after actinic illumination which was quenched by far-red light after actinic illumination and after 50-ms pulse light. C4 plants generally showed much larger pool than C3 plants. The donation of electrons from stroma was further sustained by the rise of chlorophyll fluorescence after actinic illumination which was quenched by far-red light. The reducing equivalent, possibly NADPH from malate, accumulated during actinic illumination can be donated to P700^+ Via the plasto-quinone pool in PSII deficient bundle sheath chloroplasts in C4 plants.
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