Blastocyst development after intergeneric nuclear transfer of mountain bongo antelope somatic cells into bovine oocytes

Intergeneric embryos were constructed by nuclear transfer using Mountain Bongo antelope somatic cells fused with enucleated bovine oocytes and their subsequent development in vitro was investigated. After two to six passages, starved or non-starved skin fibroblast cells were used as donor nuclei. In vitro matured bovine oocytes were enucleated by squeezing the first polar body and surrounding cytoplasm through a slit in the zona pellucida. After injection of a somatic cell into the perivitelline space, couplets were fused electrically and activated chemically, then subjected to different embryo culture treatments. Serum starvation had no effect on the frequency of cleavage to two cells or on development to the blastocyst stage in either sequential hamster embryo culture medium (HECM)-6/TCM-199 + serum or HECM-9/TC-199 + serum, or modified synthetic oviduct fluid (mSOF) culture medium. When couplets from non-starved donor nuclei were cultured, the frequency of cleavage (66 +/- 8% vs. 44 +/- 5%), development to >/=9 cells (46 +/- 6% vs. 24 +/- 4%), and formation of blastocysts (24 +/- 5% vs. 11 +/- 2%) were all significantly higher (p < 0.05) in the HECM-6 medium than in mSOF medium. In conclusion, bovine oocytes can support blastocyst development after intergeneric fusion with bongo fibroblasts. This technique could potentially be used as an alternative to using scarce bongo oocytes in attempts to propagate these endangered animals.