PARTHENOGENETIC DEVELOPMENT OF DWARF SURF CLAM, MULINIA-LATERALIS, OOCYTES TREATED WITH POLAR BODY SUPPRESSING AGENTS

Parthenogenesis following oocyte activation has been observed in a num ber of marine invertebrates, but the fate of parthenogenesis in bivalv e mollusc embryos is unclear. We used the dwarf surf clam, Mulinia lat eralis, to examine parthenogenetic development of KCl-activated oocyte s using the polar body suppressing agents caffeine and heat or cytocha lasin B. Development was followed by epifluorescence microscopy and fl ow-cytometric analysis using the DNA-specific fluorochrome DAPI. All a gents suppressed polar body formation to some degree, putatively incre asing the ploidy level and retaining a meiotic centrosome in the zygot e; but the zygotes failed to develop normally. Failure of the zygotes to develop suggests that the meiotic centrosome is incapable of partic ipating in mitosis in bivalves.