Segmental aneuploidy as a probe for structural genes in Drosophila: mitochondrial membrane enzymes.

A method for detecting possible structural genes in D. melanogaster based on gene dosage dependency is presented. By making thirty crosses between Y-autosome translocations, and an attached-4 cross, it is possible to produce large duplications (approximately 150 salivary gland chromosome bands in length) for every autosomal region with the exception of 83DE. The usefulness of the technique was demonstrated by dosage dependency of three known gene-enzyme systems: alpha-glycerophosphate dehydrogenase-1, alcohol dehydrogenase and malate dehydrogenase. A screen for genes affecting two enzymes localized on the inner membrane of the mitochondrion, alpha-glycerophosphate oxidase (alphaGPO) and succinic dehydrogenase (SHD), produced a dosage-sensitive region in each case. Region 50C-52E affected alphaGPO activity and region 28D-29F affected SDH activity. The latter region apparently includes the malic dehydrogenase-1 gene. The methodology and limitations of the technique are discussed.