Summary
The possible role of arachidonic acid and its metabolites in sea urchin egg activation was examined using inhibitors of arachidonic acid release and metabolism. Quinacrine, a phospholipase A2 inhibitor, blocked the cortical granule reaction and inhibited pronuclear migration and cleavage in fertilized eggs. Indomethacin and eicosatetrayenoic acid, blockers of arachidonic acid metabolism, had no affect on these processes. These findings suggest that phospholipase A2 activation may be important in mediating events involving cortical granule exocytosis, pronuclear morphogenesis and mitosis in fertilized sea urchin eggs, perhaps by releasing free arachidonic acid. Subsequent metabolism of arachidonic acid does not seem to be involved in processes of egg activation as inhibitors of arachidonic acid metabolism had no demonstrable effects on fertilization events following egg activation and the cortical granule reaction.