1997 Fiscal Year Final Research Report Summary
Response of photosynthetically living leaf cells to darkness
| Project/Area Number |
07454216
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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
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| Research Institution | The University of Tokyo, Graduate School of Science |
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Principal Investigator |
WATANABE Akira The University of Tokyo, Graduate School of Sciences, Professor, 大学院・理学系研究科, 教授 (70023471)
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| Co-Investigator(Kenkyū-buntansha) |
SONOIKE Kintake The University of Tokyo, Graduate School of Sciences, Assistant Professor, 大学院・理学系研究科, 助手 (30226716)
ITO Masaki The University of Tokyo, Graduate School of Sciences, Assistant Professor, 大学院・理学系研究科, 助手 (10242851)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Photosynthetic organ / cDNA cloning / Branched-chain alpha-ketoacid dehydrogenase / Arabidopsis thalinana / Direct display RT-PCR / Response to darkness / Amino acid metabolism / Gene expression |
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| Research Abstract |
The aim of this project is to find what green plants are doing in terms of gene expression in the darkness of night when they are unable to acquire living energy from photosynthesis. To this aim we have cloned more than a dozen cDNA sequences complementary to mRNA which accumulate when Arabidopsis plants are kept in the dark. We found that one of the colones encoded a novel chloroplast protein which accumulates only in young leaves in the night. Its function is not clear at present, but from the resemblance of the amino acid sequences is presumed to be related to the metabolism of sulfur-containing compounds. We speculate that this protein has a function in controlling events which occurs in the chloroplast in the night to lead to the eventual degeneration of the organelle. In ralation ot this degeneration process, we found that one of the subunits of chloroplast Clp protease which is coded for by nuclear genome was induced in the dark. We are currently examining the subunit is actually assembled in the protease complex. Genes corresponding to some of the clones were of particular interest because their expression was refulated by sugar level in the cells, that is, the expression is abolished when the leaves were fed with sucrose at 10mM.This group of genes inclede those for the two subunits of branched-chain alpha-ketoacid dehydrogenase. They seem to be repressed in daytime when sugar level is high due to active photosyntehesis, but activated in the dark through sugar stavation and the gene products work for the glyconeogenesis from free acids released from degraded protein.
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