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sox2xenopus   

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Experiment details for sox2

Delaune E et al. (2005) Assay

Neural induction in Xenopus requires early FGF signalling in addition to BMP inhibition.

Gene Clone Species Stages Anatomy
sox2.L laevis NF stage 10.5 to NF stage 13 neuroectoderm , neural plate

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  Fig. 3. FGFR signalling is required for neural induction. (A) Four-cell embryos were treated until fixation with various concentrations of SU5402, as indicated. Phenotypic classes were defined according to the severity of axial deficiencies. Class V embryos lacked muscle, NCAM-positive neural tissue and neural crests [as revealed by 12.101 (B) and 4d (C) immunostaining at tailbud stage, or by Slug RNA hybridisation at neurula stage (D)]. Class V embryos at gastrula stages lacked prospective posterior and axial mesoderm (XBra, Xcad3, ADMP; E-G), prospective haematopoietic mesoderm (Xnr2, H), but contained prospective endodermal tissue (sox17α, I). (J-M) Sox2 (J,K) and opl (L,M) expression are shown at early (J,L) or late (K,M) gastrula stages in control and class V embryos. No neural precursors are present in class V embryos. (N,O) Thirty-two-cell embryos were injected with 250 pg lacZ RNA in one A1 blastomere (animal-most, dorsal-most). In untreated controls, injected cells populate mostly the eye and the brain and some head epidermis (N). In the presence of 120 μM SU5402, embryos were class V, and the injected cells were now found entirely in the epidermis below the cement gland (O). These cells expressed the marker K81, indicating that prospective neural cells were converted into epidermal progenitors in absence of FGF activity. SU5402 is not toxic to ectoderm cells as they remain alive, and expressβ -galactosidase and K81. (A-C) Lateral view, anterior towards the left. (N) Lateral view, anterior towards the right. (D,G,J-M) Dorsal view, anterior towards the top. In M, the embryo is slightly tilted upwards. (E,F,H) Vegetal view, dorsal towards the top. (I) Hemisectioned embryo, dorsal towards the right. O, frontal view.

Gene Clone Species Stages Anatomy
sox2.L laevis NF stage 10.5 neuroectoderm

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  Fig. 8. Neural tissue development involves BMP/SMAD1-independent FGFR activity. (A-D) Stage 26 tailbud embryos immunostained for NCAM. (A) Untreated embryo; (B) class V embryo treated from stage 7 to 26 with 120 μM SU5402; (C) embryo treated similarly with SU5402 and which had received injection at the four-cell stage of lacZ, tBR (400 pg), noggin (250 pg) and Smad6 (4 ng) RNAs; (D) embryo treated similarly with SU5402 and injected at blastula stage 9 with 1 ng Noggin protein. BMP inhibitors converted epidermis into cement gland (cement glands are outlined in B-D), but did not rescue neural tissue in class V embryos. (E-G) These embryos received the same treatment and injection as in A-C, but were harvested at the early gastrula stage 10.5, and analysed for Sox2 expression. No rescue of Sox2 expression was obtained upon injection of the triple inhibitor combination in class V embryos. (H) Eight-cell embryos were injected in all four animal blastomeres with Smad6 RNA (1 ng/blastomere) and cultured in absence or in presence of 120 μM SU5402 from stage 7, as indicated. Animal caps were excised at blastula stage 9, further cultured in the inhibitor until late gastrula stage 13, and harvested at tailbud stage. Siblings were class V in this experiment. Neural induction by Smad6 is suppressed in absence of FGFR activity.

Gene Clone Species Stages Anatomy
sox2.L laevis NF stage 13 neuroectoderm , neural plate

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  Fig. 1. BMP inhibition in vivo is not sufficient for neural induction. In all panels, Sox2 expression marks prospective neural tissue, K81 expression marks prospective epidermis, XBra expression marks mesoderm, at the late gastrula stage 13, and Slug marks neural crest progenitors at early neurula stage 15. Marker gene expression is revealed in purple, while β-galactosidase activity resulting from injection of lacZ RNA as a lineage tracer is in red. (A) Sixteen-cell embryos injected with 100 pg CABR RNA in one dorsal-most animal blastomere. BMPR activation represses the neural marker Sox2 and activates the epidermal marker K81. (B) Eight-cell embryos injected animally in the two left blastomeres with lacZ (250 pg/blastomere) and tBR (400 pg/blastomere) RNAs showing neural plate expansion and epidermis suppression (u, uninjected side). (C-G) Sixteen-cell embryos injected in one ventral-most animal blastomere with lacZ (C), lacZ and tBR (400 pg, D), or lacZ and Smad6 (1 ng in E,G; 4 ng in F) RNAs. In whole embryos, BMP inhibition by Smad6 represses epidermis, but does not induce neural tissue. Ectopic neural crest could form in embryos that received 1 ng (arrow), but not 4 ng, Smad6 RNA. (G) Animal caps explanted at blastula stage 9 express Sox2 in response to Smad6 injection in ventral ectoderm cells. The inset in the lower panel illustrates that Sox2 expression (purple) is restricted to the injected region (red). (A,B) Dorsal views, anterior towards the top. (C-F) Ventral views, anterior towards the top, except right panels in E,F, which are lateral views, anterior towards the top. Scale bars: 500 μm.

Gene Clone Species Stages Anatomy
sox2.L laevis NF stage 14 neuroectoderm , neural crest , neural plate

  Fig. 4. Both pharmacological and antimorphic FGF inhibitors block neural development in a specific manner. (B,C) Four-cell embryos were injected with lacZ RNA (B), or lacZ and 5 pg v-ras (C) RNAs, and embryos were treated with 120 μM SU5402. Neural plate tissue is rescued by v-ras injection in FGFR-deficient embryos. (D-I) Four-cell embryos were injected with lacZ and 1 ng δR4 (dominant-negative FGFR4) (D,G), lacZ, 1 ng δR4 and 1 ng FGFR4 (E,H), or lacZ, 1 ng δR4 and 4 ng tR4 (activated FGFR4) RNAs (F,I). δR4 is not toxic to the cells as they retain β-galactosidase activity but no longer express Sox2. (G-I) β-Galactosidase reaction was omitted to optimise NCAM immunostaining at tailbud stage. Both FGFR4 and tR4 can rescue the loss of neural tissue due to δR4 misexpression. (J,K) Eight-cell embryos were injected in both animal blastomeres with lacZ and δR4 (200 pg/blastomere) RNAs in order to target presumptive neural tissue.δ R4-injected cells do not express Sox2 at early gastrula stage 10.5. u, uninjected side. Broken lines in G-I indicate the midline. (A-I) Dorsal view, anterior towards the left. (J,K) Dorsal view, anterior towards the top.