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Fig. 2. XOct-25 promotes commitment to neural fate at the expense of epidermal fate. The phenotypes of neurula stage embryos coinjected with GR-XOct-25 mRNA (500 pg) together with β-galactosidase (β-gal) mRNA into either one of the dorsal animal blastomeres at the 8-cell stage (A, B, E, F and I–P) or one of the ventral animal blastomeres at the 16-cell stage (G and H). In C and D, mRNA was injected unilaterally into both dorsal and ventral animal blastomeres of 8-cell stage embryos in order to determine the effect on the epidermal region. Except for controls, injected embryos were treated with DEX from the blastula stage to activate GR-XOct-25 (Oct). The overexpression of GR-XOct-25 expanded the neural plate marker Sox2 at the expense of the epidermal markers epidermal keratin and Dlx3 (compare B with D and F). In the neuroectoderm, GR-XOct-25 moderately suppressed the expression of the neuronal markers N-tubulin and Xngnr-1 (J and L). There was no effect on the expression of the mesodermal markers chordin and MyoD by XOct-25 overexpression (N and P). The expression of marker genes is shown in purple. β-gal was stained in red and the injected side of the embryo is indicated by brackets. A–F and M: frontal view; N: dorso-frontal view; G and H: ventral view; I–L, O and P: dorsal view. |
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Fig. 4. Perturbation of XOct-25 function in the ectoderm during embryogenesis. The phenotypes of neurula stage embryos coinjected with either Oct MO or 6-mismatch control MO together with β-gal mRNA into one of the dorsal animal blastomeres at the 8-cell stage. The amounts of injected antisense oligonucleotides per embryo were 5.6 ng (A–C) and 4.3 ng (G–P) for moderate amounts, and 8.6 ng (D–F) as a large amount. The reduction of Sox2 expression by Oct MO injection was rescued by coinjection of δBMPR mRNA (500 pg, C) or GR-mutXOct-25 mRNA (250 pg, F). Note that cells receiving Oct MO expressed the epidermal markers epidermal keratin and Dlx3 at the expense of the neural marker Sox2 (B, H, I, K and L). There was no effect on the expression of the mesodermal markers chordin and MyoD by XOct-25 knockdown (N and P). The expression of marker genes is shown in purple. β-gal was stained in red and the injected side of the embryo is indicated by brackets. I and L are magnifications of H and K, respectively. The edges of ectopic epidermal marker expression are indicated by dashed lines (I and L). A–F, O and P: dorsal view; G–L and N: frontal view; M: dorso-frontal view. |
