DNA-REPLICATION INITIATION BY 6-DMAP TREATMENT IN MATURING OOCYTES AND DIVIDING EMBRYOS FROM MARINE-INVERTEBRATES

6-dimethylaminopurine (6-DMAP), a potent protein kinase inhibitor, dri ves most cells into an interphasic stage. Experiments were undertaken with oocytes from three marine invertebrate species, i.e., Mytilus edu lis, Spisula solidissima, and Strongylocentrotus droebachiensis, where in oocytes were arrested at different phases of meiosis. 6-DMAP induce d a continuous DNA synthesis in meiotic cells, whereas it allowed a si ngle round of DNA replication in treated mitotic cells, regardless of species considered. The effects of 6-DMAP were accompanied in all case s by rephosphorylation on tyrosine of the p34(cdc2) homolog, the M-pha se promoting factor (MPF) catalytic subunit. The fact that 6-DMAP over comes the inhibitory control of replication during meiosis suggests th at this process depends upon protein phosphorylation, while DNA synthe sis regulation in mitotic cells relies on 6-DMAP-insensitive events. ( C) 1996 Wiley-Liss, Inc.