Fig. 1. Tribolium castaneum has two ac/sc homologs. (A) Comparison of the amino acid sequences from the bHLH domains of the Tribolium ac/sc genes (Tc-SH, Tc-Ase) with those from Drosophila (Dm-Ac, Dm-Sc, Dm-L'sc). Amino acids conserved in four or more proteins are highlighted in yellow and asterisks indicate residues conserved in all ac/sc bHLH domains. (B) Alignment of the C-terminal motif from Drosophila proneural ac/sc genes with the C-terminal motif of Tc-ASH. Conserved amino acids are highlighted in yellow. (C) Phylogenetic tree showing select invertebrate ac/sc genes; support values given at each node for distance (top) and parsimony (bottom) methods; nodes with support values less than 50 for either method have been collapsed, branch lengths are not to scale. Both distance and parsimony methods show that Tc-ASH groups within the proneural gene clade and Tc-Ase within the Asense clade. Ag-ASH, Anopheles gambiae Achaete-Scute Homolog; Ag-Ase, Anopheles gambiae Asense; Hv-ASH, Hydra vulgaris Achaete-Scute Homolog; Cs-ASH1, Cupiennius salei Achaete-Scute Homolog 1; Cs-ASH2, Cupiennius salei Achaete-Scute Homolog 2; Cc-Sc, Ceratitis capitata Scute; Cc-L'sc, Ceratitis capitata Lethal of scute; Cc-Ase, Ceratitis capitata Asense; Dm-Ac, Drosophila melanogaster Achaete; Dm-Sc, Drosophila melanogaster Scute; Dm-L'sc, Drosophila melanogaster Lethal of scute; Dm-Ase, Drosophila melanogaster Asense; Tc-ASH, Tribolium castaneum Achaete-Scute Homolog; Tc-Ase, Tribolium castaneum Asense.