Weakening Wnt signaling facilitates proto-neuromast maturation and deposition. (A-D) Wnt inhibitors reduce lef1 expression. lef1 expression is shown in the PLLp following exposure to DMSO control (A), IWR-1 (B) and XAV939 (C), and following heat shock-induced expression of ΔNTcf (D) at 31 hpf. (E,F) IWR-1 shrinks the broad leading fgf10 expression domain while exposing more spots of trailing fgf10 expression (arrows). (G,H) Premature appearance of atoh1b expression (arrows) in IWR-1-treated PLLp at ~31 hpf. (I,J) pea3 expression is not obviously altered in IWR-1-treated embryos. (K) Proto-neuromast formation is initiated closer to the leading edge in IWR-1-treated and BCI-treated embryos. **P<0.01, ***P<0.001. Error bars indicate s.d. (L) Comparison of the relative size of the lef1 expression domain at different stages of migration in embryos treated with DMSO (red) or 10 μM IWR-1 (blue), as in Fig. 2F,G. A simple linear regression model and a paired t-test confirmed that the length of the lef1 domain is significantly smaller in the IWR-1-treated embryos. P<0.0001. (M,N) Neuromast deposition in embryos treated with DMSO (M) or IWR-1 (N).
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