Molecular ecology for the purpose of terminating toxic dinoflagellate by gene analysis of some enzymes relating to PSP toxin synethesis.

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We investigated the stability of paralytic shellfish poisoning (PSP) toxin composition in the dinoflagellate Alexandrium catenella and A.tamarense, and the genetic system producing it. Using clonal axnic cultures, toxin compositions were determined in cell material from different growth phases of many populations and F_1progenies. In all isolates used, the mole percentage of toxin composition did not significantly change in any growth phase. Toxin composition analysis of over 70 strains of both species from 8 different waters indicate the occurrence of inter-and intra-specific indigenous populations from distant localities. Toxin compositions of many F_1progenies from crosses between algal strains having different toxin profiles were determined. Toxin compositions were inherited mostly in a 1 : 1 Mendelian pattern and sexuality (mating type) was not associated with toxin inheritance. These data strongly suggest that PSP toxin compositions of A.catenella and A.tamarense are stable and that Mendelian inheritance of toxin profiles occurs in both these heterothallic dinoflagellates.Furthermore we have tried to isolate some enzymes relating to PSP biosynthesis in A.tamarense and G.catenatum. Firstly, N-sulfotransferase from STX or GTX2+3 to GTX5 or C1+2 was purified from G.catenatum through several columns. The enzyme consisted of two identical subunits (63kDa) and was optmally active at pH6.0 and 25ﾟC.The activity was stimulated by Mg^<2+> and inhibited by PAPS analogue. Secondly, O-sulfotransferase which converted 11-alpha, beta -hydroxy STX into GTX2+3 was partially purified. DNA sequence of these enzymes will be analyzed in the coming year.