OKADAIC ACID ANTIBODY LOCALIZES TO CHLOROPLASTS IN THE DSP-TOXIN-PRODUCING DINOFLAGELLATES PROROCENTRUM-LIMA AND PROROCENTRUM-MACULOSUM

Thin sections of Prorocentrum lima (Ehrenberg) Dodge and Prorocentrum maculosum Faust, two dinoflagellates known to produce diarrhetic shell fish poisoning (DSP), were probed with a monoclonal antibody targeted against okadaic acid (OA), the primary toxin in DSP outbreaks. The ant ibody localizes primarily to chloroplasts and pyrenoids and, to a less er degree, cellular lysosomes. Controls on the primary antibody lack l abelling as do controls done on a non-producer of toxin, Prorocentrum micans Ehrenberg, and a paralytic shellfish poison (PSP) producer, Ale xandrium tamarense (Lebour) Balech. OA is likely to be produced by the chloroplasts of the cell and its compartmentalization in plastids may explain why producer cells are unaffected by the toxicity of OA to eu karyotic cytoplasmic phosphatases.