Fig. 8. Nv-twist. Phylogenetic analysis and gene expression. (A) Alignment of 56 amino acids from twist, atonal and nautilus proteins. (B) Phylogeny of twist sequences. The tree was constructed and labeled as in Fig. 3. Sequences included in the analysis are: ato (atonal), Drosophila, residues 256-311; ATOH1 (atonal homolog), Homo, residues 160-215; nautilus, Drosophila, residues 162-216; twi (twist), Drosophila, residues 363-417; twist, Nematostella, residues 37-92; twist, Podocoryne, residues 52-106; TWIST1, Homo, residues 109-163. (C-G) Developmental expression of Nv-twist. (C) Expression begins after gastrulation has started in a ring of endodermal cells encircling the presumptive mouth. (D) Expression continues in endodermal cells surrounding the future mouth. (E) Low magnification image of early planula stage embryos seen from the oral pole showing the ring of expression surrounding the future mouth. (F,G) As development proceeds, expression remains confined to a circum-oral ring, in the endodermal epithelium of the pharynx facing (arrow 1) and external gastrodermal wall under the tentacles (arrow 2).