Genetic control of soluble NAD-dependent sorbitol dehydrogenase in Drosophila melanogaster

Experiments utilizing standard techniques of cell fractionation and disc electrophoresis have revealed the presence of three distinctly different enzymes which catalyze the oxidation of D-sorbitol in crude extracts of Drosophila melanogaster adults. These include (1) a soluble NAD-dependent sorbitol dehydrogenase (NAD-SoDHS), (2) a mitochondrial NAD-dependent sorbitol dehydrogenase (NAD-SoDHm), and (3) a soluble NADP-dependent sorbitol dehydrogenase (NADP-SoDH). The structural gene for NAD-SoDHS has been mapped to a locus between 65.3 and 65.6 on the third chromosome by means of an electrophoretic variant and a low-activity allele. Through the use of segmental aneuploidy, this gene has been localized to the region limited by salivary bands 91B-93F. Because mutants which alter either the activity or electrophoretic effect on the mitochondrial or NADP-dependent forms, it is suggested that the enzymes in this system are coded for autonomously by different genes.