TOXIC DINOFLAGELLATE PROROCENTRUM-LIMA AND ITS ASSOCIATED BACTERIA

An immunoflorescence method, using a monoclonal antibody against okada ic acid (OA) toxin and DNA staining, was used to visualize the toxin a nd extranuclear DNA which could possibly be of intracellular bacterial origin, in the dinoflagellate species Procentrum lima Ehrenberg (Dodg e). Okadaic acid (OA) was detected within the cytoplasm oi the dinofla gellate cell, frequently near the cytoplasmic membrane in the cell per iphery and occasionally close to the nuclear membrane in the center of the cytoplasm. These results suggest that OA production could be rela ted to the peripheral chloroplast and that OA accumulation may be asso ciated with membrane lipids. OA is not co-localized with extranuclear DNA, implying that intracellular bacteria do not contain or accumulate the toxin. Comparison between axenic and non-axenic dinoflagellate cu ltures showed no differences in immunolabelling, suggesting that extra cellular associated bacteria are not essential to okadaic acid product ion by the P. lima culture. These results tend to show that the dinofl agellate cell is able to produce OA autonomously.