Figure 2.

Gene transfer efficiency of LRgeoL-(VSV-G) in bovine oocytes and zygotes. Gene transfer efficiency was evaluated by X-gal staining of embryos 4 days postsemen addition. Pronuclear injection of linearized SV-lac into zygotes was used as a control. Infection with LRgeoL-(VSV-G) was achieved by PSI at the indicated time points. (A) Oocytes at 20 hr after placing in maturation medium were infected by LRgeoL-(VSV-G) PSI. Four hours after infection, oocytes were incubated with thawed semen. X-gal staining was observed in 56% (178/316) of infected embryos. Zygotes at 18 hr postsemen addition were infected by LRgeoL-(VSV-G) PSI. X-gal staining was observed in 22% (49/226) of infected embryos. Zygotes at 18 hr postsemen addition were pronuclear injected with SV-lac, and 17% (25/144) of microinjected embryos were stained with X-gal. Cytoplasmic expression, in the case of pronuclear microinjection, does not differentiate between integration and extrachromosomal expression.