Two alternative transcripts coding for alcohol dehydrogenase accumulate with different developmental specificities in different species of picture-winged Drosophila.

Two alternate transcripts of the single copy Alcohol dehydrogenase (Adh) gene accumulate with developmental specificity in all of 12 species of Hawaiian picture-winged Drosophila which have been examined. Relative to the paradigm species D. affinidisjuncta, the Adh transcript normally restricted to larvae is found to accumulate in both larval and adult tissues in D. formella. The other Adh transcript, which normally accumulates only in adults, accumulates in third-instar D. prostopalpis larvae as well. In species hybrids, the D. formella phenotype shows additive inheritance. These observations document the existence of a novel type of genetic variability. Furthermore, such variants suggest specific properties for the biological systems that regulate ADH expression in Drosophila, and they should facilitate further experimental investigations.