Differential expression and dosage compensation of theα-amylase gene inDrosphila miranda

Theα-amylase gene ofDrosophila miranda is located on the X2-and on the neo-Y-chromosome, both developing sex chromosomes. Crosses between strains carrying different electrophoretically distinguishable alleles of theα-amylase gene were performed. Females of the F1 offspring showed the expected heterozygosity, while the males proved to be hemizygous for this locus. Only the gene on the X2-chromosome is expressed, whereas the corresponding gene on the neo-Y-chromosome is not. Estimates of theα-amylase activity in crude homogenates of male and female flies suggest strongly that theα-amylase gene is dosage compensated inD. miranda. In contrast to this situation, in all otherDrosophila species theα-amylase allele is autosomal and hence not dosage compensated.