Dynamic characteristics of the mitochondrial genome in SCNT pigs

Most animals generated by somatic cell nuclear transfer (SCNT) are heteroplasmic; inheriting mitochondrial genetics from both donor cells and recipient oocytes. However, the mitochondrial genome and functional mitochondrial gene expression in SCNT animals are rarely studied. Here, we report the production of SCNT pigs to study introduction, segregation, persistence and heritability of mitochondrial DNA transfer during the SCNT process. Porcine embryonic fibroblast cells from male and female Xiang pigs were transferred into enucleated oocytes from Yorkshire or Landrace pigs. Ear biopsies and blood samples from SCNT-derived pigs were analyzed to characterize the mitochondrial genome haplotypes and the degree of mtDNA heteroplasmy. Presence of nuclear donor mtDNA was less than 5% or undetectable in ear biopsies and blood samples in the majority of SCNT-derived pigs. Yet, nuclear donor mtDNA abundance in 14 tissues in F0 boars was as high as 95%. Additionally, mtDNA haplotypes influenced mitochondrial respiration capacity in F0 fibroblast cells. Our results indicate that the haplotypes of recipient oocyte mtDNA can influence mitochondrial function. This leads us to hypothesize that subtle developmental influences from SCNT-derived heteroplasmy can be targeted when using donor and recipient mitochondrial populations from breeds of swine with limited evolutionary divergence.