Abstract
We examined the effects of butyrolactone I (BL-I), a specific cdc2 kinase inhibitor, on the inhibition of meiotic resumption of porcine oocytes and subsequent developmental competence after somatic cell nuclear transfer (NT). Porcine follicular oocytes were cultured in a medium containing BL-I during maturation culture. BL-I suppressed germinal vesicle (GV) breakdown in a dose-dependent manner and most (98.3%) oocytes were arrested at the GV stage when they were cultured for 28 h with 100 μM BL-I, but after 48 h of culture with 100 μM BL-I half of the oocytes underwent GV breakdown. Twenty hours after release from the BL-I treatment (28-h culture), most (95.9%) oocytes reached the metaphase II stage, whereas most non-treated oocytes reached the metaphase II stage after 40 h of maturation culture. There were no differences between BL-I-treated and non-treated oocytes in meiotic progression. When oocytes were enucleated and fused with serum-starved cumulus cells, the development of NT embryos to the blastocyst stage with the BL-I-treated oocytes (12.3%) was similar to that achieved with non-treated oocytes (12.5%). The results demonstrate that BL-I could reversibly inhibit meiotic resumption of porcine oocytes, and that BL-I-treated porcine oocytes can be used as recipient cytoplasts for NT without compromising developmental competence.
