Selective transmission of mitochondrial DNA in heteroplasmic lines for intra- and interspecific combinations in Drosophila melanogaster.

The transmission of mitochondrial DNA (mtDNA) was investigated in the heteroplasmic lines of Drosophila melanogaster at 19 degrees C and at 25 degrees C. The selective transmission of one type of mtDNA was dependent on the temperature at which the lines were maintained. In heteroplasmic lines for an intraspecific combination induced by germ-plasm transplantation using D. melanogaster as a germ-plasm donor, the proportion of donor mtDNA decreased in four out of five lines examined, the decreasing rate of which being greater at 25 degrees C than at 19 degrees C. Donor mtDNA was lost by the 20th generation at 25 degrees C. For an interspecific combination using D. mauritiana as a germ-plasm donor, the proportion of donor mtDNA increased and endogenous mtDNA was replaced with donor mtDNA at 25 degrees C. But donor mtDNA was almost lost at 19 degrees C by the 14th generation in all four lines examined. Possible mechanisms involved in the temperature-dependent modes of mtDNA transmission are discussed.