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Fig. 7. Activation of Otx2 target genes is required at early and late stages of olfactory placode formation. (A), (B) Otx2-EnR inhibits the olfactory placode marker Dmrt4 at stage 21 (59%, n=29). This is rescued by co-injection of Otx2 ((B) inhibition reduced to 12%, n=33). (C–F) Otx2-EnR-GR injections: in the absence of DEX Dmrt4 expression is normal ((C) 5% affected, n=20); when DEX is added at stage 10 Dmrt4 expression is lost at stage 18 ((D) 59%, n=44). At stage 25 Dmrt4 is normal in absence of DEX ((E) 8% affected, n=26), while activation at stage 18 strongly reduces Dmrt4 ((F); 63%, n=24). (G) Otx2-E1A has no effect on Dmrt4 (0% affected, n=14). (H)–(I) Otx2 mRNA reduces Pax2 ((H) 72%, n=25), but does not change Eya1 ((I) 0% affected, n=44). All embryos were injected into the A3 blastomere at the 32-cell stage and are shown in frontal view with dorsal to the top. High magnifications of the olfactory region are shown in small panels; dotted lines demarcate placodal Dmrt4. Turquoise staining reveals the lineage tracer FDX. |
