| Project/Area Number |
07660267
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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 |
Fisheries chemistry
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
SHIOMI Kazuo Tokyo Univ.of Fish., Dept.of Food Sci.& Technol., Professor, 水産学部, 教授 (90111690)
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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 |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Corbicula japonica / Corbicula leana / Corbicula sandai / Toxicity / Proteinaceous toxins / タンパク毒 |
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| Research Abstract |
1.All specimens of the brackishwater clam Corbicula japonica obtained from various places of Japan were toxic when their aqueous extracts were intravenously injected into mice. As to toxicity, there were no sexual and seasonal variations but a local variation was obviously recognized. Two other Corbicula species (C.leana and C.sandai) were also toxic, though at much lower levels than C.japonica. Irrespective of the species, viscera were non-toxic and several muscular tissues were toxic ; the highest toxicity was observed in foot muscle for C.japonica, siphon for C.leana and mantle muscle for C.sandai. No toxicity was detected in 12 species of bivalves other than Corbicula species.
2.The C.japonica toxin was purified by hydrophobic chromatography, gel filtration and ion-exchange FPLC and shown to be a weakly basic protein with a molecular weight of 25,000 and a pI of 7.7. Its LD_<50> (intravenous injection into mice) was estimated to be 11 mug/kg. The toxin showed hemolytic activity but lacked anti-microbial activity. Although the toxins of C.leana and C.sandai could not be obtained in a pure form, they were comparable to that of C.japonica with respect to stability and molecular weight.
3.An attempt was made to improve the time-consuming purification method for the C.japonica toxin described above. As a result, the toxin was purified by only two steps comprising the binding to sheep erythrocyte membranes and ion-exchange FPLC.
4.The Corbicula toxins evoke no serious problem to the human health, since they are very unstable to heating and non-toxic upon oral administration. They are of scientific importance in that they are the first examples of proteinaceous toxins from bivalves.
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