Wnt-dependent Fgf signaling inhibits snail1b expression in the trailing domain. (A,B) Expression of snail1b and Wnt-dependent lef1 in leading domain of pLL primordium in control DMSO-treated embryos at 32 hpf. Arrow and arrowhead show snail1b in the pLL primordium and in the underlying horizontal myoseptum cells, respectively. (C,D) snail1b and lef1 expression in BIO-treated embryos. (E-J) snail1b and lef1 expression following heat shock in HS:dkk1b embryos (E,F), without heat shock in HS:dkk1b embryos (G,H) and with heat shock in non-transgenic siblings (I,J). (K,L) Expression of snail1b and Fgf-dependent pea3 at 32 hpf in control DMSO-treated embryos. (M,N) snail1b and pea3 expression in SU5402-treated embryos. (O-T) snail1b and pea3 expression following heat shock in HS:DN-fgfr1 embryos (O,P), without heat shock in HS:DN-fgfr1 embryos (Q,R), and with heat shock in non-transgenic siblings (S,T). Fluorescent anti-GFP staining in the Tg[cldnb:lynGFP] line was used to define the outline of all pLL primordia (dotted line). The primordia leading end is always to the right. n=20 for each of three independent experiments.