| Project/Area Number |
10680663
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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 | THE UNIVERSITY OF TOKYO |
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Principal Investigator |
HIRONO Masafumi University of Tokyo, Graduate School of Science, Associate Professor, 大学院・理学系研究科, 助教授 (10212177)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Chlamydomonas / actin / actin-like protein / flagella / dynein / セントリン / cAMP |
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| Research Abstract |
Chlamydomonas has only a single gene of conventional actin which has about 90% sequence identity to mammalian skeletal muscle actin. The actin is contained in the inner-arm dynein complexes as a subunit and in the fertilization tubule which elongate from the male gametes during the mating process. However, how the actin functions in the dynein complex and what regulates the actin during the formation of fertilization tubule are not known. We have shown that the Chlamydomonas ida5 mutant lacking some species of inner-arm dynein has a serious mutation in the conventional actin gene. In addition to the deficiency in dynein assembly in axoneme, ida5 gametes are unable to produce the fertilization tubule. In this study, we examined whether transformation of this mutant with cloned actin gene can rescue the mutant phenotypes. Co-transformation of the double mutant ida5arg2 with the wild-type actin gene and arginino-succinate lyase gene that suppresses the arg2 mutation yielded several transformants that displayed increased motility. Most of them were found to be able to produce the fertilization tubule. These results established that the lack of inner-arm dynein and the fertilization tubule in ida5 are consequences of its loss of conventional actin. Furthermore, we revealed that an actin-like protein (NAP) which had already been identified as a candidate molecule for substituting the actin function in ida5, has 64% amino-acid identity with the conventional actin. Thus, we suggest that two actin genes are expressed in Chlamydomonas cells and each has its own function in addition to the overlapping function.
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