Cytoplasmic transfer methods for studying the segregation of mitochondrial DNA in mice

Heteroplasmic mice represent a valuable tool to study the segregation of different mtDNA haplotypes (mtDNAs with differing alleles) in vivo against a defined nuclear background. We describe two methods for the creation of such models, differing in the resulting initial heteroplasmy levels: (1) transfer of ooplasm and (2) fusion of two blastomeres. These methods result in typical heteroplasmy of 5 % and 50 % donor mtDNA, respectively. The choice of method depends on the aim of the study. By means of breeding, even 100 % donor mtDNA can be reached within few generations.