Mutation of the Adh gene of Drosophila melanogaster containing an internal tandem duplication.

AdhnLA248 is an X-ray-induced mutation of the alcohol dehydrogenase gene of Drosophila melanogaster that lacks detectable ADH protein but is transcribed. The transcript of this mutant allele is longer than that of the wild type. This is because the mutation is a duplication of parts of the second and third exons of Adh and of the intron that normally separates them. The primary transcript of the mutant allele is processed by the removal of both of the identical copies of intron 3. This mutation presumably originated, in the haploid sperm, as two staggered single-stranded breaks that gave rise to the duplication as a consequence of replication after fertilization.