Xenbase Image ID: 85038

Figure 3. Maternal xNorrin is required for dorsal ectoderm specification. (A) The xNor-MO target sequence (green line) in xNorrin mRNA. (B) xNor-MO dose-dependently suppresses xNorrin-Myc (1.5 ng) mRNA translation in Xenopus embryos. xNorrin-Myc was detected using an anti-c-Myc monoclonal antibody. Uni, no xNorrin-Myc injected. (C-F) xNorrin is required for head formation. (C) A wild-type (WT) stage 35 tadpole. (D) xNor-MO (20 ng) caused anterior truncation (61%, n = 64) when injected into the animal regions of two dorsal cells in four- to eight-cell-stage embryos. (E) xNor-misMO-injected embryos are generally normal (88%, n = 66). (F) The anterior defects caused by NorMO were rescued by xNorrin (25 pg) mRNA (77%, n = 81). (G) Dorsal view of a wild-type tadpole at stage 45. (H) Anterior defects on only one side (arrow) were generated by injecting xNor-MO (10 ng) into one dorsal cell at the four- to eight-cell stage (63% of injected embryos showed defects in the injected side, n = 30). The other side shows normal morphology. The anterior end is to the left. (I) xNor-MO inhibits Wnt signaling in dorsal animal cells. xNor-MO and SuperTopFlash (STF) reporter plasmids were co-injected into the dorsal animal cells of eight-cell embryos. F/R luciferase: ratio of firefly luciferase reading to renilla luciferase reading. (J) Whole-mount in situ hybridization shows that Chordin expression is reduced at stage 9 (53% of injected embryos, n = 80) and stage 10 (61% of injected embryos, n = 79) in xNor-MO-injected embryos, compared to xNor-misMO-injected embryos or uninjected embryos. (K-N) Whole-mount in situ hybridization for Chordin in bisected xNor-MO-injected embryos (stage 9.5) showing that xNor-MO inhibits Chordin expression in neuroectoderm precursors (arrow) (reduction in 66% of injected embryos, n = 104) (L) compared to wild-type embryos (K) and embryos with xNor-misMO injected into dorsal animal cells at the eight- to 16-cell stage (reduction in 13% of injected embryos, n = 78) (M). Note that xNorrin mRNA (100 pg) rescues Chordin expression in the dorsal ectoderm (80% of co-injected embryos showed expression comparable to wild-type embryos, n = 50) (N). Embryos are oriented such that their dorsal side is on the right. Dotted lines indicate the boundaries between the deep mesoderm and the superficial ectoderm. Image published in: Xu S et al. (2012) Xu et al. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Gene Synonyms Species Stage(s) Tissue chrd.S chd, chordin, chrd.1, LOC108716939, X-chordin X. laevis Throughout NF stage 9 dorsal marginal zone chrd.S chd, chordin, chrd.1, LOC108716939, X-chordin X. laevis Throughout NF stage 10 dorsal marginal zone Image source: Published Larger Image Printer Friendly View

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