1996 Fiscal Year Final Research Report Summary
Molecular mechanism of gametic differentation in Chiamydomonas
| Project/Area Number |
08045043
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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 | University-to-University Cooperative Research |
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| Research Field |
電力工学・電気機器工学
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| Research Institution | Musashi Institute of Technology (1997)
Kobe University (1996) |
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Principal Investigator |
MATSUDA Yoshihiro Kobe Univ., Facul. Sci., Professor, 理学部, 教授 (20030778)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Tatsuaki Kobe Univ., Grad. SCh. Sci. Tech., Assistant, 大学院・自然科学研究科, 助手 (90281138)
BECK Christoph アルバート, ルデヴィクス大学・Biol・ Inst・ III, 教授
BECK C.F. ALbert-Ludwigs Univ., Biol. Inst., Professor
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| Project Period (FY) |
1996 – 1997
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| Keywords | Chlamydomonas / Gamete differentiation / Photomorphogenesis / Molecular control |
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| Research Abstract |
We analyzed in this research the molecular programs for gametic differentiation which was induced by nitrogen starvation and light in the unicellular green alga Chlamydomonas reinhardtli.
1. The expression of gametogenesis-specific genes (gas) during gametogenesis was analyzed by using the wild-type and the temperature-sensitive-mutant for gametogenesis (dif-2). In the wild-type cells, the gas-3 gene was expressed at the early phase of gametogenesis under nitrogen-starved conditions, while the gas-18 and gas-28 were expressed at the middle and late phase, respectively. In the dif-2 mutant cells, these genes were expressed normally at the permissive temperature (25℃), whereas none were expressed at the restrictive temperature (35℃), and the expression was started after transfer to the permissive temperature. It was noticed that the lack of expression of a gene encoding a subunit of the amino acid oxidase was also observed, suggesting a role of the DIF-2 gene product in a common pathway f
… More
or controlling both genes involved in gametogenesis and genes that allow the utilization of alternative nitrogen sources.
In C. reinhardtli, there has been debate as to whether gametogenesis requires light. We, therefore, obtained all available laboratory strains and examined requirement/non-requirement for light under the same gametogenetic conditions, which had been developed in the laboratory . It was found that laboratory strains of C. reinhardtii are divided into two groups as to where the vegetative cells require light to differentiate into gametes. Light-dependent (LD) strains were unable to become gametes in the dark, while light-independent (LI) strains could do. All the wild-type strains isolated recently from the wild showed light-dependency, suggesting that LD-phenotypes is the wild-type. The LD-cells failed to acquire flagella agglutinability, to accumulate call body-agglutinins and to from mating structures in the dark, but not the LI-gametes, lost their mating ability after transfer to darkness, indicating that the LD-cells require light not only for gametic differentiation but also for maintenance of gametic activity. Less
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