Morphogenesis of denticles and hairs in Drosophila embryos: involvement of actin-associated proteins that also affect adult structures.

We sought components that function in morphogenetic events downstream from the segmentation pathway in Drosophila embryos, so we examined mutations that affect development of adult hairs and/or bristles to identify a subset that also affect hairs and denticles on the cuticle of first instar larvae. Mutations at 4 of 23 loci surveyed cause distinct abnormalities in these larval structures, and two other loci have more subtle, variable effects. In particular, forked and singed mutants produce complex, allele-specific phenotypes. These loci encode actin-associated proteins and, consistent with that information, mutations cause abnormalities in actin bundles that support nascent hairs and denticles in stage 14-16 embryos. We suggest that interactions between these and other actin-associated proteins are important in generating the diverse shapes of the cuticular specializations seen in both larvae and adults.