2001 Fiscal Year Final Research Report Summary
Molecular mechanisms, for cell cycle restart from a quiescent phase in fission yeast
| Project/Area Number |
11680706
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | Osaka City University |
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Principal Investigator |
SHIMODA Chikashi Grad Sch. Science, Dept. Bio- and Geosciences, Osaka City University Professor, 大学院・理学研究科, 教授 (80047290)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Taro Grad Sch. Science, Dept. Bio- and Geosciences, Osaka City University Lecturer, 大学院・理学研究科, 講師 (30291082)
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| Project Period (FY) |
1999 – 2001
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| Keywords | germination / sporulation / cdc2 kinase / cyclin / cdk inhibitor / cAMP / spore wall / pollen allergen |
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| Research Abstract |
1) Signal transduction required for spore germination.: Germination of ascospores in the fission yeast Schizosaccharomyces pombe are induced by glucose. The intracellular cAMP level increased transiently by the addition of glucose. Furthermore, we found that mutations in the cyrl and pkal genes, encoding adenylyl cyclase and A-kinase, respectively, blocked the initiation of spore germination. Breaking of dormancy of spores requires activation of the cAMP/PKA signal pathway.
2) Cell cycle progression during spore outgrowth : A cell cycle following spore germination was studied. Germinated spores enter the S phase after a long (〜10 hours) G1 phase. Cd2 kinase activity increased shortly before the onset of DNA replication. Coincidently, Cig2 cyclin was accumulated and Ruml Cdk inhibitor was disappeared. In contrast, Cdc13 cyclin is not necessary for S phase. During the G1 phase, expansion growth followed by polar growth occurs. We speculate that the long G1 phase is required for cells to reach a critical cell size necessary for the onset of S phase.
3) Identification of a major spore wall protein p23 : Germination is thought to accompany chemical and morphological alteration of spore envelopes. We found that p23, a major spore wall protein, decreased gradually during germination. P23 was purified and its partial amino acid sequence was determined. This sequence was identical with the amino terminus of the isp3/meu4 gene product, The isp3 gene is transcribed during meiosis and its disruption results in reduction of sporulation ability.Isp3-GFP fusion protein localized to the spore envelope. Intriguingly, P23/Isp3 shares a characteristic alanine-rich region with pollen allergen proteins.
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