Parthenogenetic Activation of Porcine Oocytes by Electric Pulse and/or Butyrolactone I Treatment

Abstract

The goal of the present research was to study the parthenogenetic activation of porcine oocytes following treatment with the specific cyclin-dependent kinase inhibitor butyrolactone I (BL I). In Experiment I, the effective dose of BL I was determined by the rates of the subsequent pronuclear formation in oocytes after the activation. In Experiment II, BL I was further tested alone or in combination with an electric pulse. The efficiency of the various treatments to induce activation and parthenogenetic development was examined. In Experiment III parthenogenetic development of activated oocytes in two different media was compared. Cleavage and blastocyst developmental rates were examined, and number of cells in the blastocysts was determined. Our results indicate that, in pig, the optimal activation dose for BL I was 150 μM; a combined electrical and BL I treatment resulted in superior cleavage rates compared to an electric pulse, 150 μM of BL I, or 200 μM of BL I alone (74%, 60%, 41%, and 42%, respectively; P < 0.05); and the rate of parthenogenetic development of activated oocytes to the blastocyst stage in mNCSU37 medium was significantly higher than that in Whitten's medium (59% vs. 5%, P < 0.05) and the resulting day-6 blastocysts had higher cell numbers (35.5 ± 14.1 vs. 19.5 ± 2.5). This activation protocol might be useful in porcine nuclear transfer experiments and for the generation of parthenogenetic fetuses.