Lef1 determines leading dusp6 expression and inhibition of Lef1 function influences the pattern of proto-neuromast formation and neuromast deposition. (A-D) dusp6 expression is regulated by Lef1 and FGFR signaling. (A) dusp6 is expressed in the leading two-thirds of the PLLp. (B) lef1 knockdown eliminates dusp6 expression in a leading domain. (C) SU5402 treatment eliminates trailing dusp6 expression. (D) SU5402 treatment in lef1 morphants eliminates dusp6 expression in the PLLp. Bracket shows where dusp6 expression is lost. Asterisk indicates persistent dusp6 expression in prospective inter-neuromast cells. (E,F) pea3 expression shows that FGFR signaling is enhanced in BCI-treated embryos. For statistical analysis, see supplementary material Fig. S15B. (G,H) lef1 expression suggests that Wnt signaling is not obviously altered in BCI-treated embryos. For statistical analysis, see supplementary material Fig. S15A. (I,J) atoh1b expression is seen in more proto-neuromasts closer to the lead edge of the PLLp. For statistical analysis, see supplementary material Fig. S6E. (K,L) Neuromasts are deposited closer together in BCI-treated embryos. For statistical analysis, see supplementary material Fig. S16. (M) There is no apparent difference between DMSO-treated controls and BCI-treated embryos in the size of the lef1 domain over the course of PLLp migration. (N) mCherry or Dusp6-mCherry expression was induced by heat shock treatment during PLLp migration. After the PLLp had completed migration, the numbers of red fluorescent cells were counted in each neuromast (see supplementary material Fig. S17). Cells expressing Dusp6-mCherry were less likely to be deposited in neuromasts L1-4 and more likely to be deposited in L5-6 or terminal neuromasts of the PLLp. **P<0.01. Error bars indicate s.d.
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