Figure 1

Treatment with 800 μM SB-431542 or 50 μM SB-505124 at MBT prevents formation of mesoderm and endoderm. (A-F) Images of live embryos at 24hpf treated at 2.75 h with DMSO (A-C), SB-431542 (D-F; J-S), or SB-505124 (G-I). Embryos treated with SB-431542 (D-F) or SB-505124 (G-I) lack derivatives of the mesoderm and endoderm in the head and trunk, display severe cyclopia and lack Kupffer's vesicle. (J-P) Images of embryos treated with DMSO (J-N) or SB-431542 at MBT (O-S) and processed to reveal expression of markers for derivatives of dorsal mesoderm (ntl: J, O; flh: L, Q), paraxial mesoderm (myoD: K, P), intermediate mesoderm (pax2.1: M, R), and ventral neurectoderm (shhb: N, S). Dorsal views of embryos fixed at 10 h (J, L, N, P, Q, S)or 14 h (K, M, P, R). Arrowhead in (C) is the Kupffer's vesicle.