ARTIFICIAL ACTIVATION OF OOCYTES FROM SINCLAIR MINIATURE PIGS

The experiments reported in this paper are designed to evaluate in Sin clair miniature pig oocytes a number of stimuli that are known to resu lt in activation of domestic pig and mouse oocytes. The rationale for such experiments is two fold: 1) to provide an initial characterizatio n of mechanisms that may be responsible for activation at fertilizatio n in miniature pigs oocytes and 2) to initially characterize methods t hat may be useful for activating oocytes for nuclear transplantation a nd cloning. In Experiment 1 all staurosporine treated oocytes activate d; whereas, neither treatment with phorbol 12-myristate 13-acetate, no r control media resulted in any activation. In Experiment 2, A23187 re sulted in 60% of the oocytes activating while none of the controls act ivated. Experiment 3 evaluated multiple electrical pulses on oocyte ac tivation, but resulted in no significant difference after six days in culture. Experiment 4 evaluated the effect of including cycloheximide in the culture medium for the first 20 hows of the 6 day culture on, t he development of electrically activated in vivo matured Sinclair mini ature pig oocytes. Inclusion of cycloheximide during the first 20 hour s of culture increased (P=0.08) the number of nuclei present after a 6 day culture. Some compact molecule and a blastocyst were obtained aft er these treatments. It is concluded that in vivo derived oocytes from Sinclair miniature pigs respond to activation stimuli in a manner sim ilar to in vitro matured oocytes from domestic pigs, but they are more developmentally competent.