FIGURE 2:

BMP signaling is essential at 20 hpf for VPB specification. (A–C, H–M) Embryos obtained from outcrossing a hemizygous Tg(hsp70l:dnBmpr-GFP) zebrafish with homozygous Tg(ptf1a:eGFP) were heat shocked at 20 hpf and harvested at 30 hpf (L, M) 48 hpf (A–C, H–I), and 3 dpf (J, K) and examined for ptf1a:eGFP fluorescence (A–C) and hlxb9la (H, I), trypsin (J, K), and ptf1a and pdx1 (L, M) expression. (D) Graph quantifying ptf1a:GFP expression in wild-type and Tg(hsp70l:dnBmpr-GFP) heat-shocked embryos at 16, 20, 24. and 28 hpf. Data are presented as the percentage of embryos displaying normal (white), reduced (orange), or absent (red) ptf1a:GFP fluorescence. (E–G) Confocal z-lane showing activation of the BMP pathway in pancreatic cells as revealed by immunostaining with anti-pSmad 1/5/8 (green) (E) and anti-Pdx1 (red) (H) antibodies. Double pSmad 1/5/8⁺ and Pdx1⁺ cells are observed on the merge picture (G). White lines indicate the VPB. DPB, dorsal pancreatic bud; s, somite.