Fig. 2

fscn1a-depletion disrupts endoderm formation.

(a-e) The expression of endodermal markers in fscn1a morphants and control embryos at shield stage (a, Scale bar, 200 µm), 75% epiboly stage (b; Scale bar, 200 µm), 14 h.p.f. (c; Scale bar, 200 µm), 28 h.p.f. (d; Scale bar, 200 µm in the left two panels and 100 µm in the right two panels) and 36 h.p.f. (e; Scale bar, 200 µm). (a) Lateral views with dorsal to the right. (b-e) Dorsal views with anterior to the top. Dorsal forerunner cells (DFCs) were indicated by a black arrowhead (b) and the developing gut tube was indicated by black star (c). The liver and dorsal pancreatic buds were indicated by a black and a red arrowhead, respectively (d,e). Embryos in a, b, c and d were injected with 4 ng fscn1a mis-MO1 and MO1, while embryos in e were injected with 2 ng indicated MOs. (f-j) The expression of endodermal markers in MZfscn1a mutants and wild-type embryos at 75% epiboly stage (f; Scale bar, 200 µm), 14 h.p.f. (g; Scale bar, 200 µm), 18 h.p.f. (h; Scale bar, 200 µm), 28 h.p.f. (i; Scale bar, 200 µm in the left two panels and 100 µm in the right two panels) and 36 h.p.f. (j, Scale bar, 200 µm). Note that the formation of the endodermal related tissues including the developing gut tube, the liver and pancreatic buds and the endoderm pouches was progressively recovered from 18 h.p.f. in MZfscn1a mutants. (k,l) Ectopic expression of zebrafish fscn1a or mouse fscn1 (mfscn1) in fscn1a morphants (k; Scale bar, 200 µm) or MZfscn1a mutants (l; Scale bar, 200 µm) restores endoderm formation. Embryos were injected with 4 ng fscn1a MO1 alone or together with 150 pg fscn1a mRNA or mfscn1 mRNA at the one-cell stage and collected at the 75% epiboly stage for in situ hybridization.