Proteinaceous toxin selected from causative dinoflagellates of paralytic shellfish poisoning and its effect on crustacean

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Toxicity of cell free media of Alexandrium tamarense to crustacean was confirmed by a bioassay using brine shrimp, Artemia salina. Similar effects were also observed in A. catenella and A. minutum. On the other hand, PSP toxicity of toxic dinoflagellate such as A. catenella decreased significantly under an optimum growth conditions, indicating that toxin productivity would be very low when they form red tide. During the course of a batch culture, toxicity to brine shrimp of cell free media did not showed a parallel relationship to the PSP toxicity. These results indicated that toxicity of eel free media to brine shrimp is possibly caused by some other compound than PSP toxins. Brine shrimp toxicity was found in both higher and lower molecular weight fractions when the cell free medium was fractionated with ultra-filtration (MW 10kda). Several components with different polarities were recognized to show the brine shrimp toxicity in the lower molecular weight fraction. Some of them were identified as polvunsaturated fatty acids and glycolipids by GC or HPLC analyses. These substances showed a hemolytic activity, suggesting that crustacean died with a cytotoxicity of these substances. High molecular weight fraction was further fractionated by gel filtration and ion exchange chromatography to isolate toxic principleas. Three toxic components were found in the this fraction. These components showed absorption maxima at 280 nm and lost their activities by protease treatment, indicating that these are composed of protein. Molecular weight of these toxic proteins was estimated to be 10, 25, and 100 Kda, respectively. Among these toxins, components with the highest and lowest molecular weight showed hemolytic activity and collapsed diatom cells. On the other hand, protein with molecular weight of 25 Kda did not show any cytotoxicity but an acute toxicity to brine shrimp, suggesting that this component possess neurotoxicity.