Fig. 6. Rescue experiments. Embryos were injected in one blastomere at the two-cell stage with Xiro1 (1 ng) and HD-GR-EnR (0.5 ng) (A,D,G,J), or HD-GR-E1A (0.5 ng) (B,E,H,K), or HD-GR (0.5 ng) (C,F,I,L). The inducible constructs were activated around stage 10 (A-F) or 12.5 (G-L) and the expression of Otx2 and Gbx2 were analyzed at early neurula stage. Embryos injected with a mixture of Xiro1 and HD-GR-EnR and activated around stage 10 show an expansion and caudal shift of Gbx2 (A, broken lines, 90%, n=27) and a caudal expansion of Otx2 midbrain expression domain (D, broken lines, 70%, n=23). The overexpression of Xiro1 with HD-GR-E1A or with HD-GR and activation at stage 10 rescue the expression of both Otx2 and Gbx2 (B,E and C,F, respectively). The expression of Otx2 and Gbx2 is rescued in the embryos injected with mixtures of Xiro1 with HD-GR-EnR (G,J), with HD-GR-E1A (H,K) or with HD-GR (I,L) activated at stage 12-12.5. Broken lines show the displacements of gene expression. Arrowheads indicate the injected sides. The percentage of rescue of normal expression for each experiment was 75%.