Abstract
We are characterizing members of the Transforming Growth Factor-β (TGF-β) superfamily in the red flour beetle, Tribolium castaneum, in order to examine the evolutionary conservation of the structure and function of TGF-β-like genes during insect development. A decapentaplegic-like gene of the TGF-β superfamily was isolated in Tribolium (Tc dpp) that is similar in sequence, organization, and expression to the Drosophila melanogaster dpp gene (Dm dpp). Conserved features include a high degree of sequence similarity in both the pro-domain and mature domains of the encoded polypeptide. In addition, the position of an intron within the protein-coding region is conserved in Tc dpp, Dm dpp, and two bone morphogenetic protein genes of the TGF-β superfamily in humans, BMP2 and BMP4. Consensus binding sites for the dorsal transcription factor are found within this intron in Tc dpp similar to the intronic location of several dorsal binding sites in Dm dpp. During embryogenesis, Tc dpp is expressed in an anterior cap of serosa cells at the blastoderm stage, in the dorsal ectoderm at the lateral edges of the developing and extended germ band, and in the distal tips of developing embryonic appendages. Several aspects of embryonic expression, similar in both flies and beetles, suggest conserved roles for dpp in cellular communication during the development of these distantly related insects.
