Regulatory differences in developmental expression of alcohol dehydrogenase are related to interspecies differences in ethanol tolerance of Drosophila.

Biochemical properties and expression patterns of alcohol dehydrogenase were compared among members of the virilis phylad of Drosophila. Quantitative differences in stage- and tissue-specific expression of ADH of D. virilis, D. novamexicana, D. texana and D. americana were observed. These differences seem to correlate with the temporal differences in ethanol tolerance among these species. Quantitative differences in ADH protein levels account for most, if not all, of the activity differences between species. Analysis of the interspecific hybrids revealed that these differences arise by a mechanism affecting monomer synthesis. A comparison with earlier studies, where independently evolved regulatory differences were related to adaptations, revealed contrasting underlying mechanisms.