Fig. S4

Posteriorizing TGFβ activity is only partly dependent on Nodal signals. In situ hybridization with cyp26 (A,C,E,G,I,K,M) or hoxb1b (B,D,F,H,J,L,N) probes is shown for wild-type embryos (A,B), untreated ich embryos (C,D), ich embryos treated with bmp2bMO (E,F), SB431542 (G,H), sqtMO and cycMO (K,L), or bmp2bMO in combination with SB431542 (I,J) or sqtMO and cyc MO (M,N). A small molecular inhibitor of the TGFβ pathway, SB431542, has no effect on untreated ich embryos (G,H), but when it is applied to bmp2bMO injected ich embryos, it anteriorizes the neuroectoderm (I,J). These embryos have gastrulation defects; the arrowheads point to the position of the stalled germ-ring. Coinjection of sqtMO and cycMO with bmp2bMO results in a slight expansion of the cyp26 domain (M), and a mild reduction of the hoxb1b domain (N), showing that the posteriorizing effects of TGFβ signaling are dependent to some extent on Nodal-independent signals. Injection of sqtMO along with cycMO into untreated ich embryos has no effect on cyp26 and hoxb1b expression (K,L). SB431542 was used at 2.4 mM concentration; sqtMO and cycMO were 3 mM each. Wild-type embryos (A,B) are shown in a dorsal view, ich embryos (C-N) from a lateral view. All embryos are at ~10 hpf.