Diacylglycerol content of Chaetopterus oocytes during maturation and fertilization.

The resumption of meiotic maturation in Chaetopterus oocytes is believed to be initiated by activation of protein kinase C (pkC). Since the physiological activator of pkC is diacylglycerol (DG), we examined the DG content of the oocytes before and during germinal vesicle breakdown (GVBD). Unstimulated oocytes contained 366 +/- 34 fmol DG per cell. This value increased to approximately 430-500 fmol 3-5 min after normal induction of GVBD and declined thereafter to 147 +/- 7 fmol per cell. Fertilization increased the DG levels slightly, 3-5 min after insemination. These results strongly support the hypothesis that pkC is a physiological activator of GVBD in this species.