| Project/Area Number |
07044179
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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 | University of Tsukuba |
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Principal Investigator |
BABA Tadashi Institute of Applied Biochemistry, University of Tsukuba, Associate Professor, 応用生物化学系, 助教授 (40165056)
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| Co-Investigator(Kenkyū-buntansha) |
HARDY Daniel M Department of Cell Biology and Biochemistry, Texas Tech University Health Scienc, 細胞生化学部, 助教授
GERTON George L Department of Obstetrics and Gynecology, University of Pennsylvania School of Me, 医学部, 準教授
YANAGIMACHI Ryuzo Department of Anatomy and Reproductive Biology, University of Hawaii Medical Sch, 医学部, 教授
SATO Hideaki Institute of Medical Science, University of Tokyo, 医科学研究所, 助教授 (80093243)
OKABE Masaru Research Institute for Microbial Diseases, Osaka University, 微生物病研究所, 助教授 (30089875)
TOYADA Yutaka Research Center for Protozoan Molecular Immunology, Obihiro University of Agricu, 原虫病分子免疫研究センター, 教授 (90050418)
HARDY Daniel 米国テキサス工科大学, 細胞生化学部, 助教授
渡辺 研 米国ラホーヤがん研究所, 研究員
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 1996: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1995: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Fertilization / Sperm / Oocyte / Acrosin / Gene targeting / acrosome reaction / Zona pellucida / Serine protease |
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| Research Abstract |
A fertilizing mammalian sperm penetrates into zona pellucida, an extracellular matrix surrounding oocyte, to fuse the plasma membranes of both cells. It is a general concept that as a consequence of acrosome reaction of sperm, the acrosomal components are released, and interact with the zona pellucida. Acrosin, an endoprotease with a trypsin-like cleavage specificity, is localizing in the acrosome matrix as an enzymatically inactive zymogen, proacrosin. The physiological function of acrosin has long been believed to be a limited proteolysis of the zona pellucida, enabling sperm to penetrate to the oocyte surface. Here we show that male mice homozygous for a targeted mutation in the acrosin gene are still fertile in spite of the complete loss of the acrosin protease activity in the sperm. In vitro fertilization test reveals a time delay of the homozygous mouse sperm in penetrating into the zona pellucida. This delay is likely due to the fact that production of a 42-kDa serine protease is suppressed in vitro in the homozygous mouse sperm. Therefore, acrosin is not essential for the penetration of sperm into the zona pellucida. Rather, the function of acrosin in the early stages of fertilization may be implicated in the acceleration of formation of the active 42-kDa trypsin-like protease that is a candidate for the protein acting on the sperm penetration.
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