Pronounced segregation of donor mitochondria introduced by bovine ooplasmic transfer to the female germ-line

Ooplasmic transfer (OT) has been used in basic mouse research for studying the segregation of mtDNA, as well as in human assisted reproduction for improving embryo develop-ment in cases of persistent developmental failure. Using cattle as a large-animal model, we demonstrate that the moderate amount of mitochondria introduced by OT is transmitted to the offspring’s oocytes; e.g., modifies the germ line. The donor mtDNA was detectable in 25 % and 65 % of oocytes collected from two females. Its high variation in heteroplasmic oocytes, ranging from 1.1 % to 33.5 % and from 0.4 % to 15.5%, can be explained by random genetic drift in the female germ line. Centrifugation-mediated enrichment of mitochondria in the pole zone of the recipient zygote’s ooplasm and its substitution by donor ooplasm led to elevated proportions of donor mtDNA i