Additional file 6: of Reiterative use of FGF signaling in mesoderm development during embryogenesis and metamorphosis in the hemichordate Ptychodera flava

Phylogenetic and expression analyses of the two MHC genes identified in P. flava. (A) The amino acid sequences of the myosin head domains of the MHC proteins from 15 species were used to construct the phylogenetic tree. The three different types within the myosin superfamily, type I, II and V, were all well resolved. The two P. flava MHCs are grouped in type II (green branches), one within the skeletal/cardiac muscle MHC subgroup (Pf-stMHC) and the other in the smooth/non muscle subgroup (Pf-smMHC). Values at each node are Bootstrap inferences and the values lower than 50 are not shown. The scale bar indicates the substitutions per site. The abbreviations of the species names are: Amq, Amphimedon queenslandica; B, Bovine; Bb, Branchiostoma belcheri; Ce, Caenorhabditis elegans; Ci, Ciona intestinalis; Dm, Drosophila melanogaster; Hs, Homo sapiens; Mm, Mus musculus; Pf, Ptychodera flava; Pl, Placopecten magellanicus; Rn, Rattus norvegicus; Sk, Saccoglossus kowalevskii; Sc, Saccharomyces cerevisiae; Sch, Schistosome mansoni; Sp, Strongylocentrotus purpuratus. (B1-C2) In situ hybridization analyses of P. flava stMHC (B1-B2) and smMHC (C1-C2) in 43 hpf and 73 hpf embryos. The embryo in the inlay of B2 was viewed from the dorsal side to show the expression of stMHC in the muscle string. The embryo in the inlay of C1 was observed from the apical side. All panels are shown in the same scale, according to the scale bar in B1. The green arrow indicates the pharyngeal muscle and the black arrowheads denote the muscle string in B2. (PNG 1292 kb