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. 2009 Jan 14;136(4):575–584. doi: 10.1242/dev.027334

Fig. 2.

Fig. 2.

Syn4 is required for neural induction. Sox2 and Nrp1 expression was analysed by whole-mount in situ hybridisation. (A-H) MO-injected samples analysed at stage 14. The lineage tracer in shown in the insets. (A) Syn4 MO injected in one animal blastomere of an 8-cell stage Xenopus embryo. Note the inhibition of Sox2 expression on the injected (right-hand) side (60%, n=45). (B) Similar to A, but injection with control MO. No effect on Sox2 expression is observed (0%, n=57). (C) Syn4 MO was injected into the dorsal animal blastomere (A1) at the 32-cell stage. Note the inhibition of Sox2 expression in the injected region (arrowhead) (55%, n=50). (D) Syn4 mRNA mutated in the MO sequence region was co-injected with Syn4 MO into the A1 blastomere of a 32-cell stage embryo. Note the rescue of the expression of Sox2 (8%, n=66). (E) Syn4 MO injected into one animal blastomere of an 8-cell stage embryo. Note the inhibition of Nrp1 expression on the injected side (95%, n=42). (F) No inhibition is observed with the control MO (0%, n=21). (G) Control-morpholino-injected ectoderm was grafted into an uninjected embryo. Sox2 expression is normal (100%, n=10). Black dashed line indicates the anterior border of Sox2 expression. White dashed line outlines the graft. Inset shows the position of the graft by its fluorescence. (H) Syn4 MO-injected ectoderm was grafted into an uninjected embryo. Sox2 expression is absent from the grafted area (asterisk; 70%, n=10). Inset shows the position of the graft by its fluorescence. (I-N) Analysis of Sox2 expression at stage 11. (I) Expression of Sox2 is initially observed in the dorsal region (arrowhead). (J) Expansion of Sox2 expression by BMP inhibition [BMP antagonists: truncated BMP receptor (tBR) and chordin (chd) mRNA]. (K) Early induction of Sox2 was eliminated by co-injection of Syn4 MO (69%, n=50). (L) Control animal caps, showing no expression of Sox2. (M) Animal caps taken from embryos injected as in J, showing weak upregulation of Sox2. (N) Animal caps taken from embryos as in K. Co-injection of Syn4 MO blocks Sox2 induction.