SEQUENCE AND EVOLUTION OF THE DROSOPHILA-PSEUDOOBSCURA GLYCEROL-3-PHOSPHATE DEHYDROGENASE LOCUS

The Gpdh genomic region has been cloned and sequenced in Drosophila ps eudoobscura. A total of 6.8 kb of sequence was obtained, encompassing all eight exons of the gene. The exons have been aligned with the sequ ence from D. melanogaster, and the rates of synonymous and nonsynonymo us substitution have been compared to those of other genes sequenced i n these two species. Gpdh has the lowest rate of nonsynonymous substit ution yet seen in genes sequenced in both D. pseudoobscura and D. mela nogaster. No insertion/deletion events were observed, and the overall architecture of the gene (i.e., intron sites, etc.) is conserved. An i nteresting amino acid reversal was noted between the D. melanogaster F ast allele and the D. pseudoobscura gene.