Intracellular effects of okadaic acid in the blue mussel Mytilus edulis, and rainbow trout Oncorhynchus mykiss

The effects of okadaic acid (OA) on protein phosphatase (PP) and glycogen synthase (GS) activity was investigated in the blue mussel and rainbow trout. In both species, PP activity was inhibited by 200 nM inhibitor-2 (I-2) as well as 2 nM OA indicating the presence of both type 1 and type 2A phosphatases. GS activity was measured in an in vitro tissue slice method. Ten μM OA inhibited GS activity in rainbow trout but did not alter GS activity in the blue mussel. Also, feeding the mussels the OA-producing algae Prorocentrum lima had no effect on GS. These results seem to indicate that there may be protective mechanisms against harmful effects of OA in the blue mussel.