Origin of tetrodotoxin and toxification mechanism in juvenile puffer fishes

河豚毒素对河豚鱼的毒性是一个重要的研究课题。天然河豚鱼的毒性具有地域性和个体差异性，而人工养殖河豚鱼无毒，这可能是河豚鱼中毒的食物链机制。在岩手县的Okkirai湾，夏季和秋季会出现剧毒的河豚幼鱼。然后，为了实际证明食物链机制，我们在Okkirai湾进行了饲养实验。将无毒培养的幼鱼Kusafugu Takifugu niphobles限制在浸没在海水中的塑料鱼笼（80 × 56 × 37cm）中，并通过狭窄的间隙从外部侵入笼中喂养天然活生物。饲养实验在Okkirai湾的两个地点进行了两到四周。（鬼泽渔港和Sodenosawa），并在夏季和秋季重复了三年。每次饲养试验后，用小鼠测定所用样品的毒性，以监测是否发生了腐败 ...更多信息 或不.在Sodenosawa进行的总共14次实验中，没有一次显示发生了冻结。另一方面，在Onisawa的14个实验中，从8月到10月进行的5个实验显示发生了变性。上述结果表明，无毒的养殖河豚鱼幼鱼在一定时间、一定地点的海水中饲养后，会产生毒性。在上述实验中，养殖河豚鱼幼鱼的中毒被认为是由于摄入天然生物而发生的，但没有确定致病生物。然后，在下一个实验中，我们试图缩小致病微生物的范围。在Onisawa渔港附近设置了含有无毒养殖幼鱼的养鱼池。将港口的海水抽上来，分别依次用2、0.3和0.1mm的筛网过滤器过滤。将用0.3或0.1 mm筛网过滤器过滤并浓缩的微生物提供给饲养罐并进料至kusafugu。在8月至10月进行的实验表明，发生中毒。这表明致病微生物非常小。少

The toxification of puffer by tetrodotoxin is an important subject. The facts that the toxicity in natural puffer varied regionally and individually, and that the cultured puffer was innocuous may suggest that the toxification was caused by the food chain mechanism. In Okkirai bay, Iwate prefecture, highly toxic juvenile puffer fish appear in summer and autumn. Then, to have actual proof of the food chain mechanism we conducted rearing experiments in Okkirai Bay. Non-toxic cultured juvenile kusafugu Takifugu niphobles were confined in a plastic fish cage (80x56x37cm) submerged in seawater and fed natural living organisms intruding into the cage from outside through narrow gap. The rearing experiments were conducted for two to four weeks at two spots in Okkirai Bay. (Onisawa fishing port and Sodenosawa) and repeated during summer and autumn for three years. After each rearing experiment, the toxicity of specimens used were assayed using mouse to monitor whether toxification had occurred … More or not. At Sodenosawa among total 14 experiments conducted none showed toxification occurred. On the other hand, at Onisawa among 14 experiments 5 experiments conducted from August to October showed toxification occurred. Above result suggest that non-toxic cultured juvenile kusafugu become toxic when reared in a cage submerged in seawater in certain times at certain spots.In the experiments described above, toxification of cultured juvenile puffer was supposed to be occurred by ingesting natural living organisms, but the causative organisms were not identified. Then, in the next experiment, we tried to narrow the range of the causative organisms. Fish rearing tanks containing non-toxic cultured juvenile kusafugu were set up near Onisawa fishing port. Seawater of the port was pumped up and filtered by 2, 0.3 and 0.1 mm mesh filters respectedly and sequentially. Filtered and condensed microorganisms with 0.3 or 0.1 mm mesh filters were provided to the rearing tanks and fed to the kusafugu. In the experiment conducted from August to October showed toxication occurred. This suggests that the causative organisms are very small. Less