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Figure 6. xNorrin induces neural formation independent of β-catenin signaling.
(A) xNorrin dose-dependently induced neural marker (Xpax6, otx2, NCAM, and Sox2) expression. The induction is independent of mesoderm formation (m-actin: muscle actin) and could occur in the presence of a β-catenin-MO. RNA and MO were injected at the one-cell stage, and the caps were dissected around stage 8 and cultured until they reached stage 15. -RT, no reverse transcription; WE, whole embryo; WT, wild-type. (B) xNorrin induced Sox3 expression in animal caps (89% of xNorrin injected caps showed the expression, n = 45). xNorrin mRNA (300 pg) was injected into the animal pole of two-cell embryos. Sox3 expression in stage 15 animal caps was analyzed with in situ hybridization. WT, wild-type animal caps; xNorrin, xNorrin-mRNA-injected caps. (C) xNorrin induced the expression of ectopic neural and anterior markers in whole embryos. xNorrin mRNA (300 pg) was injected into the ventral animal tier cells of 32-cell embryos. Expression of Sox3 (by δBMPR: 80%, n = 30; by xNorrin: 73%, n = 30) and XAG1 (by δBMPR: 69%, n = 35; by xNorrin: 79%, n = 34) were induced at ectopic sites. β-gal, β-gal-mRNA-injected embryos; δBMPR: δBMPR-mRNA-injected embryos; WT, wild-type uninjected embryos; xNorrin: xNorrin-mRNA-injected embryos. Arrows: ectopically induced Sox3 or XAG1. Sox3 expression in wild type is shown in a dorsal view, while XAG1 expression in wild type is shown in an anterior view. All other embryos are shown in a ventral view, except the embryo in the β-gal/Sox3 panel, which is in a lateral view. |
