Supplemental figure 1. Expression profiles of Zic and β-catenin from early gastrula to neurula stages Spatial expression patterns of Xenopus Zic1, Zic2 and Zic3 were examined with whole-mount in situ hybridization analysis with a series of cut embryos at various stages from late blastula [Stages (St.) 9.5-9.75] to neurula (St.14). The three Zic genes were chosen for the analysis because they were expressed strongly during gastrulation (Supplemental figure 2). The animal pole is up and dorsal is right. At early gastrula stages, the expression of Zic genes was observed in the dorsal mesoderm area. Zic1, Zic2, and Zic3 expression was observed in the dorsal involuting mesoderm area, as well as in neuroectoderm, throughout the gastrula stages (St. 10.5, 11, 12). Zic3 expression was clearly observed in whole involuting mesoderm surrounding yolk plug, as well as previously reported (Kitaguchi et al., 2000). Zic expression in gastrula mesoderm mostly overlapped with that of β-catenin.