Studies on toxification of puffer fish.

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As a part of the research on the mechanism of toxification in puffer fish, following experiments were conducted.Eggs were obtained from the mature kusafugu and torafugu and fertilized artificially and hatched in aerated aquariums. The larvae were reared with rotifers and copepods for about 20 days in indoor aquariums and then transferred to out door concrete tank and reared with a commercial eel diet for a few years to provide the experimental fish all the time. During this periods, the toxicity was checked at the interval of two month.In various conditions, we examined the accumulation of toxin administered intraperitoneally or subcutaneously. No difference in accumulation was detected in regard to injection methods. The amount of accumulation was directly proportional to the amount of administration and the toxins recovered were 50 and 30 % in kusafugu and torafugu, respectively and were found mainly in the liver of kusafugu and skin of torafugu.The occurrences of TTX derivatives such as anhydTTX, 6-epiTTX, 4-epiTTXt and 11-deoxyTTX were reported. Two of these derivatives were injected into cultured fish and the amount of derivatives remained and the distribution in the fish. Their behavior were almost similar to that of TTX.We examined whether non-toxic puffer fish become toxic by administration of TTX producing bacteria or not. Thirty kusafugu and ten torafugu were fed the diet contained the bacteria for 30 days. The only one torafugu became weakly toxic with toxicities of 0.2 and 1.5 MU/g in the liver and skin, respectively.