Xenbase Image ID: 85039

Figure 4. xNorrin activity is restricted to the ectoderm. (A-F) Injection of NFL into ventral vegetal cells at the eight-cell stage induced partial secondary axes. Wild-type (WT) embryos (stage 28) (A and D). Injection of Wnt8 mRNA (10 pg) into ventral vegetal cells in eight-cell embryos induces complete secondary axis formation (stage 28) (69% of injected embryos showed secondary axes, n = 85) (B and E). NFL mRNA (600 pg total; 200 pg each) co-injection of ventral vegetal cells in eight-cell embryos induces partial secondary axis formation (stage 28) (45% of co-injected embryos showed secondary axes, n = 105) (C and F). Whole-mount in situ hybridization for Sox3 in stage 28 embryos (D-F). Note that NFL induces Sox3 expression in the partial secondary axis (arrowhead in [F]). The black lines in (A-C) indicate the section planes in (G-I), respectively. (G-I) Histological sections of embryos at stage 30. A wild-type embryo (G). Wnt8 mRNA injection induced both secondary neural tube and notochord (H). NFL co-injection induced secondary neural tube but not notochord formation (I). Arrowhead: neural tube; arrow: notochord. (J-L) Immunostaining of notochords with the monoclonal antibody MZ15. Wild-type embryo with single notochord (all examined embryos) (J and J'). An embryo injected ventrally with Wnt8 mRNA (10 pg) showed two notochords (induced secondary notochord and the primary notochord) (all examined embryos with secondary axes) (K and K'). An embryo injected ventrally with NFL (200 pg each) showed only the primary notochord (arrows), with notochord tissue absent in the partial secondary axis (arrowheads) (all examined embryos with partial secondary axes) (L and L'). Embryos are at stage 30. (M-R) NFL and Wnt8 induced Chordin expression in different domains in the ventral cells. Whole-mount in situ hybridization was used to evaluate Chordin expression in stage 10 embryos. Chordin expression in wild-type early gastrula (M and P). Wnt8 mRNA (10 pg) injection into ventral vegetal cells induced Chordin expression both in the superficial layer and in the deep layer of the marginal zone (87.5% of injected embryos showed the expression in both layers, n = 24) (N). Injection of NFL mRNAs (200 pg each) into the same domain induced Chordin expression mainly in the superficial layer (76% of injected embryos showed the expression, n = 30) (O). Injection of Wnt8 into the ventral-animal cells of eight-cell embryos induced Chordin expression both in the ectoderm and in the mesoderm (84% of injected embryos showed the expression in both layers, n = 25) (Q). Injection of NFL mRNAs (200 pg each) into the same domain of eight-cell embryos induced Chordin expression only in the ectoderm (72% of injected embryos showed the expression, n = 32) (R). Arrowheads: superficial layer (O) or ventral ectoderm (R); arrows: deep layers on the ventral side. All embryos in (M-R) are shown with their dorsal sides to the right. Dotted lines delineate the superficial layer and deeper layer on the ventral side. 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 sox3.S Sry, Xlsox3, xSox3, Xtsox3 X. laevis Throughout NF stage 28 brain forebrain midbrain hindbrain spinal cord 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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