Developmental rate and ploidy of embryos produced by nuclear transfer with different activation treatments in cattle.

Bovine oocyte activation is one of the essential elements that determine the success of nuclear transfer and the subsequent development of cloned embryos. Three methods for oocyte activation, including 5 microM ionomycin (5 min, Group 1) alone, ionomycin+1.9 mM 6-dimethylaminopurine (DMAP, 3h, Group 2), and ionomycin+10 microg/ml cycloheximide (CHX, 3h, Group 3) were compared for the development of embryos produced by somatic nuclear transfer (SCNT) to parthenotes and IVF counterparts.

Nuclear remodelling and the developmental potential of nuclear transferred porcine oocytes under delayed-activated conditions.

It is still unclear whether nuclear envelope breakdown and premature chromosome condensation are essential for the reprogramming of the donor nucleus following somatic nuclear transfer. To address this, we determined the ability of delayed-activated or simultaneously activated porcine oocytes to undergo nuclear remodelling and development following somatic cell nuclear transfer. A small microtubule aster was observed in association with decondensed chromatin following nuclear transfer, suggesting the introduction of a somatic cell centrosome.