Stimulation of poly(adenosine diphosphate ribose) synthase activity of Xenopus germinal vesicle by progesterone.

A practical procedure for the isolation of massive numbers of GV from oocytes of Xenopus laevis at various stages of oogenesis was developed. The method is simple, rapid, and easy to perform. The isolated GV possess high activity of poly(ADP-ribose) synthase. Incubation of class-A oocytes (stages V and VI) with progesterone resulted in a stimulation of the poly(ADP-ribose) synthase activity in the GV. The stimulation of enzymatic activity occurred prior to GVBD. This stimulatory effect of progesterone on enzymatic activity was blocked by cycloheximide and actinomycin D, suggesting that induction is dependent on protein and RNA synthesis. Progesterone, however, was unable to cause disintegration of GV or to stimulate poly(ADP-ribose) synthase activity of class-B oocytes (stages III and IV). This finding suggests that the oocytes must progress to a certain stage of differentiation before progesterone can induce GVBD or stimulate poly(ADP-ribose) synthase activity.