Patterns of pigmentation color states regulated by the y locus in Drosophila melanogaster

Ethyl methane sulfonate was used to induce a new class of heat-sensitive yellow (y: 1-0.0) alleles. A single cold-sensitive allele was discovered among the previously existing y mutants. An analysis of both temperature- and nontemperature-sensitive mutants has shown that y is a complex pattern forming gene. Although the y gene normally functions in every cell of the adult cuticle, it is expressed independently in each different cuticle structure. The need for this pattern of expression is revealed by the finding that y temperature sensitivity occurs at different times in each cuticle forming cell type. This observation suggests that the y gene functions at different times in the cells which form the various structures of the cuticle and therefore must be controlled independently in each cell type.