Fig. 6

Germ-ring expression of chordin and goosecoid in embryos with impaired Wnt8/β-catenin signaling is dependent on Nodal and FGF signaling pathways. Circumferential germ-line expression of chd (D) and gsc (J) in ich embryos depleted of β-catenins by co-injection of βcat1MO and βcat2MO (MO1 + MO2) was eliminated in embryos co-injected with additional MOs against sqt and cyc (E and K) or with mkp3 RNA to inhibit FGF signaling (F and L). Uninjected control ich embryos and ich embryos injected solely with sqtMO + cycMO or with mkp3 RNA did not express chd (A–C) or gsc (G–I). The widespread ubiquitous expression of bmp4 in ich embryos (M and S) is somewhat reduced when the embryos are co-injected with βcat1MO and βcat2MO (P and V). Injection of ich embryos with sqtMO + cycMO (N and T) or with mkp3 RNA (O and U) does not reduce bmp4 expression. Injection of the four MOs, sqtMO + cycMO + βcat1MO + βcat2MO (Q and W), or mkp3 RNA + the two βcat MOs (R and X), also did not reduce bmp4 expression, except in the latter case, the expression was less uniform with greater expression towards the margin. Results for eve1 expression were essentially identical to that of bmp4 (data not shown). Although only one embryo is shown per panel, results were completely uniform for all embryos in each panel (n > 25 in each case). Embryos are all at 70% epiboly and are shown in animal views (A–R) and for the embryos of (M–R), also shown in lateral view (S–X).