Figure 4

Phylogenetic tree and embryonic expression of S. ciliatum Msi and Elav genes. A, This is a Bayesian tree inferred from the RRM2 motif of the RNAbp, Elav and Musashi. ML bootstrap values greater than 500 and posterior probabilities generated by MrBayes greater than 0.5 are displayed. The tree was rooted with the Pabp subfamily. Names are prefixed as in Figure 1 except from: Ac, Aplysia californica; Ame, Apis mellifera; Mb, Monosiga brevicollis; Lg, Lottia gigantea and Ta, Trichoplax adhaerens. B–K Whole mount in situ hybridization: B-D, SciMsiA expression in sponges containing oocytes (B); embryos during pre-inversion showing expression in the cruciform cells (cc, arrows) and macromeres (C) and no expression in the larva (D). E-G, SciMsiB expression in oocytes (E), in cc and macromeres in embryos during post-inversion (F), and expression in the macromeres in the larva (G). H-K, SciElav whole mount in situ of sponges containing oocytes (H); during pre-inversion SciElav is seen in cruciform cells and weak in macromeres (I, J); and by post-inversion SciElav expression is predominant in macromeres (K). The asterisk indicates macromeres at the posterior pole of the embryo and larva.