Development of interspecies nuclear transfer embryos reconstructed with argali (Ovis ammon) somatic cells and sheep ooplasm.

Interspecies nuclear transfer has already achieved success in several species, which shows great potential in recovery and conservation of endangered animals. The study was conducted to establish an efficient system for in vitro argali (Ovis ammon)-sheep embryo reconstruction via interspecies somatic cell nuclear transfer (iSCNT). The competence of domestic sheep cytoplasts to reprogram the adult argali fibroblast nuclei was evaluated, and the effects of enucleation methods and donor cell passage and cell state on the in vitro development of argali-sheep cloned embryos were also examined. Sheep oocytes could support argali and sheep fibroblast cell nuclei transfer and develop to blastocysts in vitro. Oocytes matured for 21–23 h and enucleated by chemically assisted enucleation (CAE) had a higher enucleation rate than blind enucleation (BE), but the development rate of iSCNTembryos was the same (P>0.05). Moreover, passage numbers of fibroblast cells <10, as well as the cell cycle stages did not affect the development rate of iSCNT reconstructed embryos. Thus sheep cytoplasm successfully supports argali nucleus development to blastocyst stage after optimising the nuclear transfer procedure, which indicates that iSCNT can be used to conserve endangered argali in the near future.