Overexpression of Bmp2b under a heat-shock promoter partially rescued hepatoblast specification in zebrafish embryos lacking Fgf signaling. Embryos obtained from crossing a hemizygous Tg(hsp70:bmp2b)fr13 female with a hemizygous Tg(hsp70l:dnfgfr1-EGFP) male were heat shocked at 18 hpf and harvested at 30-32 (A-K) or 38-40 (L-Q) hpf. The expression of hhex (A-F), prox1 (G-K) and cp (L-Q) was then examined. hhex, prox and cp expression in the liver region mostly recovered in a majority of the embryos overexpressing Bmp2b and lacking Fgf signaling (E,F,J,K,P,Q, arrows), whereas their expression in embryos lacking Fgf signaling was strongly reduced (C,D,I,N,O, arrows). Twenty-five percent of the double hemizygous embryos did not show recovery of prox1 expression. The expression of hhex and prox1 in the embryos overexpressing Bmp2b (B,H, arrows) was comparable to that in wild-type siblings (A,G, arrows); cp expression was enhanced in the embryos overexpressing Bmp2b (M) compared with wild-type siblings (L). The percentage of the embryos exhibiting a similar expression is indicated in the lower left corner (n=11-12). All images are dorsal views, anterior up.
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