Inhibition of two homeotic mutants of Drosophila by 5-bromodeoxyuridine and fluorouracil.

Nasobemia (Ns) and spineless-aristapedia (ssa40a) are dominant and recessive homeotic mutants of Drosophila which convert parts of the antenna to leg structures. Exposure of Ns and ssa40a larvae to half-lethal concentrations of 5-bromodeoxyuridine (BUdR) and flourouracil (FU) together or separately during the presumptive time of gene action suppresses the expressivity and penetrance of the mutants.