PARTHENOGENETIC ACTIVATION OF PIG EGGS BY EXPOSURE TO PROTEIN-KINASE INHIBITORS

The objective of the present study was to assess the effect of low con centrations of protein kinase inhibitors on activation. Pig eggs were electrostimulated or cultured with the following: 10 mu M 1-[5-isoquin olinylsulfonyl]-2-methylpiperazine HCl H7 for 24 h; 100 mu M H7 for 24 h; 10 nM staurosporine for 24 h; or with 20 mu M staurosporine for 20 min followed by Whitten's medium for 24 h. Rates of pronuclear format ion in eggs (n = 1240) subjected to these treatments were: untreated, 6.2%; electrostimulated, 77.1%; 10 mu M H7, 10.0%; 100 mu M H7, 65%; 1 0 nM staurosporine, 24.2%; and 20 mu M staurosporine, 67.3% (significa nce at P less than or equal to 0.05: 10 mu M H7 vs untreated, not sign ificant; 20 mu M staurosporine vs 100 mu M H7, not significant). Perce ntages of eggs (n = 125) expressing a 22-kDa band after treatment were : untreated, 37.5%; electrostimulated, 100%; 10 mu M H7, 72%; 100 mu M H7, 66.7%; 10 nM staurosporine, 40.0%; and 20 mu M staurosporine, 77. 3% (significance at P less than or equal to 0.10: 100 mu M H7, 10 nM s taurosporine and 20 mu M staurosporine vs 10 mu M H7, not significant; 100 mu M H7 and 10 nM staurosporine vs untreated, not significant). T ransmission electron microscopy of ultrathin sections of treated eggs revealed that cortical granules were present in over half the untreate d eggs, as well as over half of the eggs treated with 100 mu M H7 or 1 0 nM staurosporine; in contrast, all cortical granules were absent fro m electrically-activated eggs. The results indicate that long-term exp osure of eggs to low concentrations of broad-spectrum protein kinase i nhibitors induces some of the events commonly associated with fertiliz ation.