SELECTIVE TRANSMISSION OF MITOCHONDRIAL-DNA IN HETEROPLASMIC LINES FOR INTRASPECIFIC 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.