Genetic analysis of temperature-dependent transmission of mitochondrial DNA in Drosophila

In artificially induced mitochondrial DNA (mtDNA) heteroplasmy in Drosophil a, the effects of chromosome substitution on temperature-dependent selectio n in mtDNA transmission were investigated. Using two strains of D. melanoga ster, bw;e(11) and y;bw;st, which showed a different temperature dependency in mtDNA transmission, chromosomes were substituted reciprocally, and mtDN A of D. mauritiana was introduced into each newly constructed strain. For e ach heteroplasmy, the transmission of mtDNA was examined at 25 degrees C an d 19 degrees C. When either the second or the third chromosome of the y, bw ;sr strain was substituted with that of the bw,e(11) strain, the temperatur e-dependent selection in mtDNA transmission was altered. The selection was not changed when either the second or the third chromosome of the bw;e(11) strain was substituted with that of the y;bw;st strain, or even when both t he second and the third chromosomes of the bw;e(11) strain were substituted with those of the y,bw;st strain. These results suggest that the temperatu re-dependent selection in mtDNA transmission is co-operatively regulated by gene products that are encoded by the X, second and third chromosomes.