Spontaneous mutations affecting glycerol-3-phosphate dehydrogenase enzyme activity in Drosophila melanogaster.

Significant genetic variance in glycerol-3-phosphate dehydrogenase (GPDH) activity was observed between chromosome lines of Drosophila melanogaster that had each accumulated spontaneous mutations for approximately 300 generations. No restriction map variation was found in a 26-kb region surrounding the entire Gpdh gene. The restriction analysis used is capable of detecting insertions/deletions larger than 0.05 kb. The survey would also detect chromosomal recombinations that include the entire Gpdh coding region. Therefore, if the spontaneous mutations that affected the enzyme activity are located inside the Gpdh gene region, then they are base pair substitutions or structural changes that are smaller than the limit in resolution described above.