DAVIS, G.K.*; WITTKOPP, P.J.; STERN, D.L.; Princeton University; Cornell University; Princeton University: The evolution and regulation of Ubx in the pupal legs of Drosophila

The fruit fly Drosophila melanogaster possesses a small region of naked cuticle on the T2 femur from which trichomes (hairs) are excluded. Other members of the subgenus sophophora, such as Drosophila simulans, instead possess a large naked region at this location. This interspecific morphological difference has previously been shown to be due in large part to changes in the gene Ubx, which is capable of repressing trichomes in the T2 femur during pupal development (Nature 396: 463-466). With the ultimate goal of identifying this evolutionarily relevant region of Ubx, we are working to identify the cis-regulatory region responsible for the repression of trichomes in melanogaster. Our ongoing approach has been to test 1) the effects of specific deficiencies in non-coding regions of Ubx on the size of the naked region and 2) the ability of various non-coding regions to functionally rescue Ubx alleles that show an almost complete loss of naked cuticle. This approach has allowed us to narrow the candidate region likely to contain the putative pupal leg enhancer of Ubx and should soon provide us with a basis for future comparisons with simulans.