Fig. 1

Pdx1 is increased in Hh-deficient embryos by 24 hpf. (A-D) pdx1 expression at 16.5 hpf (A,B) and 28 hpf (C,D) in wild-type (A,C), cyclopamine-treated (B) and smo^1a590 mutant (D) zebrafish embryos. At 16.5 hpf, pdx1-expressing cells (white arrowheads) begin converging at the midline (A), and by 28 hpf they have coalesced into a single cluster corresponding to the dorsal pancreatic bud (black arrowhead) (C). In Hh signaling-deficient embryos, the stripes of pdx1 expression are expanded (D) and remain separated (B,D) as pdx1-expressing cells fail to initiate medial migration. (E,F) hnf1ba expression in the foregut (arrows) at 30 hpf in smo^1a590 mutants (F) versus wild type (E). (G,H) cpa2 expression in the exocrine pancreas at 3 dpf in smo^1a590 mutant embryos (H) versus wild type (G). All images in A-H are dorsal views, anterior to the left. (I) qPCR of pdx1 and ptc1 expression levels at different developmental stages in embryos lacking Hh signaling (mean ± s.e.m.). Expression of pdx1 was initially reduced at 16.5 hpf but significantly elevated at 24 hpf in cyclopamine-treated embryos as compared with untreated controls and at 26 hpf in smo^1a590 mutants as compared with wild-type siblings. Asterisks denote a significant change versus control by at least two s.d. (J) A representative image of dissociated cells from a cyclopamine-treated Tg(pdx1:GFP) embryo at 28 hpf. (K) Quantification of GFP⁺ cells in untreated (wt) and cyclopamine-treated (cyc) Tg(pdx1:GFP) embryos at 28 hpf. The y-axis indicates the number of GFP⁺ cells. All cyclopamine (25 μM) treatments were initiated at 2 hpf until harvest.