Studies on proteinaceous toxins newly found in bivalves belonging to the genus Corbicula

1.取自日本各地的半咸水文蛤，其水提物经小鼠静脉注射均有毒性。在毒性方面，没有性别和季节变化，但存在明显的局部变化。另外两种河蝎(C.leana和C.Sandai)也是有毒的，尽管其毒性水平远低于日本仓鼠(C.Japan onica)。无论种类如何，内脏都是无毒的，几种肌肉组织是有毒的；日本对虾的足部肌肉毒性最高，尖吻对虾的虹吸肌和桑代的外套肌的毒性最高。该毒素经疏水层析、凝胶过滤和离子交换FPLC纯化，为弱碱性蛋白，分子量为25,000，等电点为7.7。小鼠静脉注射的LD_(50)为11微克/公斤。该毒素具有溶血活性，但缺乏抗微生物活性。虽然不能获得纯净的鱼腥藻毒素，但它们在稳定性和相对分子质量方面与日本鱼毒素相当。3.对上述耗时较长的日本鱼毒素纯化方法进行了改进。该毒素只需结合绵羊红细胞膜和离子交换FPLC两个步骤即可得到纯化。4.河豚毒素对人体健康没有严重影响，因为它对加热非常不稳定，经口无毒。它们具有重要的科学意义，因为它们是双壳类蛋白质类毒素的第一个例子。

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.