Figure 3

gbx1 acts as a mediator of the Wnt8 hindbrain posteriorizing signal. (A) Control embryo at 24 h, (B) gbx1-injected embryo (200 pg), (C) wnt8-injected embryo (400 pg). gbx1 overexpression mimics wnt8 gain-of-function; the embryos are truncated anteriorly. The red arrowhead indicates the position of the ear. (D-G') Animal pole views at 60% epiboly after ISH with otx2. (D) Control embryo, (E, E') gbx1-injected embryos (200 pg), (F) embryo injected with wnt8 morpholinos, (G, G') embryos co-injected with gbx1 mRNA and wnt8 morpholinos. Expansion of the otx2 domain in the wnt8 morphant is rescued by co-injection with gbx1 mRNA. (H-K') Dorsal views at the tailbud (tb) stage after ISH with otx2 (blue) and krox20 (red). (H) Control embryo, (I, I') gbx1-injected embryos, (J) embryo injected with wnt8 morpholinos, (K, K') embryos co-injected with gbx1 mRNA and wnt8 morpholinos. Loss of krox20 and posterior expansion of the otx2 domain in the wnt8 morphant is rescued by gbx1 mRNA.