Decapentaplegic

Decapentaplegic (dpp) is a member of the transforming growth factor-B (TGF-B) superfamily of proteins. This superfamily includes a diverse group of growth and differentiation factors that are important for cellular communication in development. In insect development dpp plays several important roles, including (1) establishing dorsal/ventral polarity in insect embryogenesis, (2) structuring the mesoderm, (3) defining boundaries between segment compartments in appendage (including eye) development . Dpp, along with wingless and hedgehog, defines the position of future limbs, including wings, legs and antennae. Dpp interacts with several other important pattern forming genes including engrailed, wingless and hedgehog. Dpp occurs as a single-copy gene in all insects studied (Yamamoto et al. 2004, Sanchez-Salazar et al. 1996). The gene encodes for a protein consisting of 395 amino acids in the Hymenoptera (Athalia rosae, Yamamoto et al. 2004). There is a single intron which appears conserved across all the known insect complete sequences analyzed (Sanchez-Salazar et al. 1996).

Complete Hymenoptera decapentaplegic sequences are known for Apis mellifera (Genbank accession number XM_395420) and Athalia rosae (Genbank accession number AB121072). Additional sequences include complete sequences for Drosophila melanogaster (Genbank accession number M30116) and Tribolium castaneum (Genbank accession number U63132), and partial sequences for Precis coenia (Genbank accession number L42141), and Schistocerca americana (Genbank accession number V23785).

Dpp has not been used in any previous phylogenetic studies of insects although the molecular evolution of the gene was examined by Newfeld et al. (1997). We initially aligned dpp sequences from Athalia and Apis to develop primers spanning an approximately 1000 bp region including one intron. Our primers amplify a broad sample of bee families, but the PCR products are often faint. Sequences of initial PCR products reveals that there is a single intron with length variation ranging from 100 to 450 bp in length. Wingless and dpp should be comparable data sets for phylogenetic analysis and our experience with wingless indicates that these genes may be excellent data sets for resolving deep divergences in bees. This is one of our most promising new data sets for bee phylogeny because the gene is clearly single-copy in Hymenoptera (Yamamoto et al. 2004).