Fig. S2

Antagonistic activity of the dominant-negative form of Wnt8a. (A) Injection of 10 pg of Wnt8a mRNA into one animal pole blastomere at the 64-cell stage of a wild-type embryo results in ectopic expression of dharma at the animal pole of a sphere-stage embryo. (Left) Lateral view. (Right) Animal pole view of the same embryo oriented dorsal to the Right. (B) Injection of 10 pg of Wnt8a mRNA in one animal pole blastomere at the 64-cell stage in an embryo previously injected at the one-cell stage with 500 pg of DN-Wnt8a mRNA does not result in ectopic expression of dharma. In addition, endogenous dharma expression at the margin is strongly attenuated. The antagonistic effect of DN-Wnt8a on the induction of dharma at the animal pole is higher than the induction of endogenous dharma because the injection of Wnt8a mRNA in animal pole blastomeres is performed 2 h after fertilization and 1.5 h after injection of DN-Wnt8a, whereas endogenous Wnt8a mRNA present in the cortical cytoplasm can be translated earlier. (Left) Lateral view. (Right) Animal pole view of the same embryo oriented dorsal to the Right. (C and D) Compared with its expression in wild type (WT) (C) the forebrain and midbrain expression of cyp26a1 (arrows) is strongly extended posteriorly (D) in embryos injected with 500 pg of DN-Wnt8a mRNA at the 8- to 16-cell stage. (E and F) At 30 hpf, embryo injected with 500 pg of DN-Wnt8a mRNA displays a phenotype (E) highly similar to the phenotype of Wnt8a morphant (F). Lu