9630179 Denell Studies of Drosophila melanogaster have shown that embryonic developmental commitments along most of the anterior-posterior axis are controlled by homeotic genes in two clusters: the Antennapedia complex (ANTC) and bithorax complex. The homeotic genes encode transcription factors and share a motif, the homeobox which encodes homeodomains important to the sequence-specific DNA binding activity of their proteins. Early studies of the homeotic genes of the red flour beetle, Tribolium castaneum, showed that it has a single homeotic complex (Hox)representing the fly clusters in juxtaposition. Comparative molecular studies suggest that such a single Hox complex arose very early in animal evolution, and that the genes in such complexes play important roles in regulating developmental commitments throughout the kingdom. This study is focused on the ANTC-like portion of the Tribolium homeotic complex. Differences in mutant phenotypes between Antennapedia orthologs of Drosophila and Tribolium suggest that the regulation of thoracic developmental decisions is altered as well as those regulating commitments in the larval head. A deficiency spanning the region covering the labial, deformed and sex combs reduced ortholog will serve as the basis for extensive mutagenesis in this region. The molecular organization and sequence of those orthologs will be determined as will the molecular nature of a group of interesting gain-of-function mutations of the proboscipedia ortholog. The cloned regions will also be used as the basis for a walk across this portion of the complex and the generation of a physical map. A critical assessment of whether the Tribolium complex includes an ortholog of the Drosophila maternal effect gene bicoid will also be possible. %%% In general, insects share a common body plan but its components have evolved incredible morphological diversity. Drosophila melanogaster is a experimental organism about which much is known on the moleculap and genetic level. The development o f Tribolium as a second insect genetic system has been a major effort but because beetles and flies share a common body plan but are diverged from each other to a degree that allows reasonable morphological and molecular comparisons, the results of this study will significantly add to our understanding of how evolution occurs at the molecular level. ***
