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Fig. 3. Syn4 overexpression neuralises ectoderm. (A-D) Anterior view, dorsal to the top (A,B); ventral view (C,D). (A,C) 500 pg of NLS-β-gal mRNA was injected into the A4 blastomere of a 32-cell stage Xenopus embryo, and the expression of Sox2 (A) and epidermal keratin (Epk) (C) was analysed by in situ hybridisation. (B,D) 1 ng of Syn4 mRNA was injected into the A4 blastomere of a 32-cell stage embryo, and the expression of Sox2 (C; 96% of induction, n=87) and Epk (D; 80% of inhibition, n=70) was analysed. (E,F) Higher magnification of embryos injected as in B,D. Arrows indicate nuclei stained with X-Gal (blue). (G-J) Dorsal (G,I) and ventral (H,J) views of embryos injected as in B with Syn4 mRNA. No ectopic expression of MyoD (0%) or Xbra (0%) was observed. Inset in H shows injected fluorescein. (K-N) Animal cap (AC) assay for Sox2 (K,L) or Epk (M,N) expression. (K,M) Control caps express only Epk. (L,N) Syn4 mRNA-injected animal caps express Sox2 and downregulate Epk. |
