Cytoplasmic transfer of resistance to antimycin A in Chinese hamster cells

A mutant subline of V79 Chinese hamster cells resistant to antimycin A (ANT) was obtained by treatment with ethyl methanesulfonate followed by serial selection in ANT-containing medium. Clonal derivatives of the resistant line are less susceptible than parent cells to growth inhibition by ANT in mass populations and show a higher plating efficiency in graded levels of inhibitor. Resistance to ANT is stable in drug-free medium and follows a pattern of incomplete dominance in hybrids between resistant and sensitive cells. No cross-resistance to chloramphenicol or other unrelated compounds was observed. Cytoplasmic transmission of ANT resistance can be readily demonstrated by fusing enucleated cytoplasts from resistant donors to sensitive recipient cells. The resulting cytohybrids ("cybrids") grow selectively in ANT but are identical karyotypically with the recipient cell type. As a putative mitochondrial marker, ANT resistance may be usefully combined with chloramphenicol resistance for studies on segregation and recombination in the mitochondrial genome of mammalian cells.