Fig. 1

Fig. 1 Disruption of Shh signaling alters pancreas development. (A) Homozygous 48-hpf INS-GFP transgenic zebrafish. Untreated embryos (left) contain a compact multicellular cluster of GFP-expressing cells. Addition of 50 μM cyclopamine at 4 hpf (right) blocks formation of GFP⁺ islets. Some isolated, single GFP-expressing cells remain (arrows). (B) 48 hpf WT zebrafish in situ hybridized as whole-mount embryos with a proinsulin riboprobe depict normal clusters of insulin-expressing cells in the pancreas budding from the right side of the endoderm (left). 48 hpf Syu^t4-/- embryos have lost all insulin expression (middle) or exhibit expression (right) in isolated single cells (arrowheads). (C) Early insulin expression in a 24-hpf WT (left) and syu embryo (right). (D) Hybridization of WT embryos with a proglucagon probe (left) reveals cells in the perimeter of the islet as well as in an isolated cell within the gut at 48 hpf (arrow). No mRNA for this neuroendocrine hormone is seen in syu embryos (right). (B–D) Views are dorsal, with anterior to the left.