| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1993: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1992: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
1. Plroteinaceous toxins were newly found in the skin mucus and roe of the lamprey Lampetra japonica. One gram of the skin mucus and roe was evaluated to kill 70 and 215-800 mice with a body weight of 20g, respectively. Both toxins showed no hemagglutinating and hemolytic activities ; the roe toxin also lacked antimicrobial activity.
2. The mucus toxin was very unstable and hence its purification was not achieved. On the other hand, the roe toxin was purified to an electrophoretically pure state by column chromatography on CM-cellulose and hydroxyapatite and FPLC on Mono S.The purified toxin exhibited high lethal activity upon i.v. injection into mice ; the LD_<50> was estimated to be 33 mug/kg. It was basic in nature and its molecular weight was determined to be 40,000 by SDS-PAGE in the absence of 2-mer captocthanal, Analysis by SDS-PAGE in the presence of the reducing reagent revealed that the toxin was comprised of two kinds of subunits with molecular weights of 30,000 and 10,000. The amino acid composition was characterized by low contents of sulfur-containing amino acids (half-Cys and Met).
3. None of the 21 species of fish examined had toxins in their roes. in contrast, as many as 9 of 54 species of fish were found to contain toxins in the skin mucus. Toxins in 3 species of anguillid fish (Anguilla japonica, Anguilla anguilla and Muraenesox cinereus), which were highly toxic, were all acidic proteins with a molecular weight of about 400,000. They were also immunologically comparable to one another. It was noticeable that sphingosine and gangliosides showed inhibitory effects on the lethal activity of the A.japonica and A.anguilla toxins.
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