Fig. 1

smo^s294 acts as a dominant-negative and reveals a requirement for Hh signalling in endodermal cell proliferation. (A-E) In situ hybridisation for sox17 at 9 hpf showing (A-C) dorsal view and (D,E) animal pole view. smo^s294 mutant (B) and smo morphant (C) zebrafish embryos showed a reduction in sox17-positive endodermal cells compared with wt siblings (A). Activation of Hh signalling by injection of ptc1 and ptc2 morpholinos (ptc MOs) (E) caused an increased number of sox17-positive cells compared with controls (D). See also supplementary material Fig. S1. (F) Presence of pHH3 (red) in Tg(sox17:EGFP)-positive endodermal cells (green) at 9 hpf (dorsal view). Inset illustrates higher magnification view of one pHH3-positive endodermal cell. (G,H) Quantification of Tg(sox17:EGFP)-positive (G) and Tg(sox17:EGFP) and pHH3 double-positive (H) cells in control and smo morphant embryos. Bars show mean number of cells (G) or mean percentage of double-positive cells (H); error bars indicate s.e.m. n=18 embryos for control and n=23 for smo morphant embryos in three independent experiments.