Combined effects of protein synthesis and phosphorylation inhibitors on maturation of mouse oocytes in vitro.

ABSTRACT

In denuded mouse oocytes, neither 3 nor 5 hours of preincubation in dbcAMP (1 mM) and cycloheximide (10 micrograms/ml), followed by further 3 hours in cycloheximide only, lowered the rate of GVBD (93% and 92%, respectively). It means that 3 and 5 hours preincubation in cycloheximide did not impair the ability of mouse oocytes to resume meiosis in medium with the protein synthesis inhibitor. To test the combined effects of inhibition of protein phosphorylation and protein synthesis, oocytes were cultured for 3, 4, or 5 hours in 2 mM of 6-DMAP and subsequently for 3 hours in 10 micrograms/ml cycloheximide. The incubation in 6-DAMP for 4 or 5 hours diminished (63% or 35% of GVBD, respectively) the ability of mouse oocytes to resume meiosis when subsequent protein synthesis was blocked by cycloheximide. However, the highly condensed bivalents were always visible in GVs. Thus the above treatment did not prevent chromatin condensation although GVBD was blocked.