| Project/Area Number |
01570043
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General physiology
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| Research Institution | Nagoya University |
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Principal Investigator |
KURODA Hideyo Nagoya Univ.,Sch. of Sci., Assoc. Prof., 理学部, 助教授 (50064845)
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| Co-Investigator(Kenkyū-buntansha) |
SOKABE Masahiro Nagoya Univ., Sch. of Med., Assoc. Prof., 医学部, 助教授 (10093428)
SATO Hidemi Nagoya Univ. Sch. of Sci. Prof., 理学部, 教授 (40109260)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1989: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | IP_3 / IP_3 receptor / calcium release / calcium channel / sea urchin egg / fertilization / イノシト-ルミりん酸 / イノシト-ル三りん酸 |
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| Research Abstract |
A transient increase in intracellular calcium concentration occurs in sea urchin eggs during fertilization. Inositol 1,4,5,-triphosphate(IP_3) is thought to be the second messenger which activates calcium channels of intracellular store and to cause the Ca-transient. However, there is no direct evidence for such a IP_3-activated Ca channel in sea urchin eggs. These experiments aimed to show the evidences.
1. IP_3 caused a transient release of Ca^<2+> from microsomal fraction of unfertililized eggs. The release was inhibited by the application of heparin (1 mg/ml). We found in addition, that caffein also caused a transient release of Ca^<2+> from the microsomal fraction in dose dependent manner. Heparin did not block the release. This means that caffeine causes a Ca release via a different mechanism from the IP_3-induced Ca release.
2. We tried to measured the current passing a IP_3-induced Ca releasing channel. Single channel recordings of the microsomal membrane which fused with a planar bilayer membrane were examined. Several kinds of Ca^<2+>, K^+ and Cl^- channels were found but no IP_3-induced Ca channel was observed.
3. Another approach to show the existence of IP_3- induced Ca releasing channel must be the purification of "IP_3-receptors" from the microsomal fraction. IP_3 binding proteins of about 200 KD were obtained. The reconstitution of the protein into an artificial membrane is now examining.
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