Effect of mitochondrial DNA composition on the cellular properties of interspecific hybrid cells

Four subclones with single species of mitochondria and three subclones with both parental mitochondria were isolated from a mouse-rat hybrid cell line H2. The effects of the coexistence of different species of mitochondria on cellular properties were examined in these clones. Growth properties were studied by comparing the plating efficiencies and doubling times. The numbers of growing colonies and the doubling times of all the subclones were found to be almost the same, indicating that these growth properties were not affected by the presence of both mouse and rat mitochondria within the cells. The correlation between the expression of chloramphenicol (CAP)-resistance and the relative contents of mtDNA of CAP-resistant (CAP^r) rat and CAP-sensitive (CAP^s) mouse parent cells in the subclones were also examined. The expression of CAP resistance was measured as the relative plating efficiency. Subclones with a high content of mtDNA from CAP^r rat parent cells showed high relative plating efficiency.