Fig. 4

Fig. 4 Inhibition of Fgf signaling increases the number of cas- and foxA2-expressing endodermal cells in bon and fau mutants. (A–J) Lateral views of zebrafish embryos with dorsal to the right. bon or fau heterozygote intercrosses were injected with oep and XFD mRNAs at the 1- to 4-cell stage and were examined for cas or foxA2 expression at the 80% epiboly stage (8. 3 hpf). Inhibition of Fgf signaling can increase the number of cas- and foxA2-expressing endodermal cells in both bon and fau mutant embryos. (K) Effects of the inhibition of Fgf signaling on the number of cas- or foxA2-expressing endodermal cells in bon mutant embryos. The number of cas- or foxA2-expressing endodermal cells was counted at the 80% epiboly stage on both the left and right lateral sides of the embryos, which we determined to be representative of whole embryos. The embryos analyzed were cas-expressing endodermal cells in oep-injected WT (n = 21) and oep-injected (n = 15) and oep,XFD-injected (n = 20) bon mutant embryos; foxA2-expressing endodermal cells in oep-injected WT (n = 24) and oep-injected (n = 12) and oep,XFD-injected (n = 23) bon mutant embryos. Error bars represent the standard error. *P < 0.0001, Student′s t test. (L) Effects of the inhibition of Fgf signaling upon the number of cas- or foxA2-expressing endodermal cells in fau mutant embryos. Zebrafish embryos at the 80% epiboly stage (8. 3 hpf) were scored as demonstrating higher cas or foxA2 expression levels if they exhibited a greater than 50% (yellow), 20–50% (red) or 0–20% (blue) increase in endodermal cells. However, because oep,XFD mRNAs injection greatly increases the number of cas- and foxA2-expressing endodermal cells, it is difficult to determine their exact number. The embryos analyzed were cas-expressing endodermal cells in oep-injected (n = 14) and oep,XFD-injected (n = 17) fau mutant embryos; foxA2-expressing endodermal cells in oep-injected (n = 12) and oep,XFD-injected (n = 15) fau mutant embryos.