Expression of the yolk-protein genes in the mutant doublesex dominant (dsxD) of Drosophila melanogaster

SUMMARY Adult flies mutant for doublesex dominant (dsx D ) are intermediate in phenotype between males and females. The dsx D mutation acts in the heterozygous state to transform only flies with two X chromosomes into intersexes, XY flies are unaffected by the mutation. Yolkprotein synthesis, which normally occurs in the ovaries and fat bodies of females, but not in males unless stimulated with 20-hydroxy-ecdysone, is reduced. The dsx D fat body synthesizes less yolk proteins throughout adult life, and the gonads rarely make yolk proteins. Using cloned yolk-protein genes as probes for measuring transcript levels we have shown that expression of these genes in dsx° is regulated both transcriptionally and post-transcriptionally. We suggest that the dsx D locus regulates the expression of the yolk-protein genes from within the fat body cells and does not operate by modulating ecdysteroid titres in the adults.