Molecular characterization of Tclabial and the 3 ' end of the Tribolium homeotic complex

The homeotic selector gene labial is located at the 3' end of the Antennape dia complex (ANTC) and is required for proper head development in Drosophil a. We have cloned and characterized the Tribolium ortholog of labial, Tclab ial (Tclab). Similar to Drosophila labial, Tclab contains a single large in tron upstream of the homeobox. In contrast, Tclab lacks an intron within th e homeobox. The Tribolium ortholog of chaoptic, Tcchaoptic, transcribed fro m the opposite strand, is located immediately downstream of the homeotic co mplex, and its 3'UTR overlaps that of Tclab by 50 nucleotides. We have also sequenced the 13.5 kb interval between Tclab and maxillopedia (the Triboli um ortholog of Drosophila proboscipedia). In contrast to Drosophila, there is not a cluster of cuticle genes in this region. Finally, we have examined the expression of Tclab transcripts in Tribolium embryos. As previously de scribed for Drosophila and other insects, the expression of Tclab is specif ic to the intercalary segment.