Fig. 3. Xsix3 regulates the expression of genes that control cell differentiation, and its expression is controlled by Hedgehog and Neurogenin signalling. (A-C) Embryos injected unilaterally with Xchh (A) and Xngnr1 (B,C) display ectopic expression of Xsix3 (A) and N-tubulin (B), and repression of Xsix3 (C). (D) Comparison of the expression of Xsix3 (light blue) with that of Xngnr1 (purple) in a stage 13 embryo. (E-K) Embryos injected with Xsix3 display repression of N-tubulin (E, the arrow indicates the repressed expression in the trigeminal ganglion), elrC (F) and Xngnr1 (J), and ectopic expression of Zic2 (G), Hairy2 (H) and Xash3 (I). (K,L) Embryos injected with Xsix3 and treated with HUA show expansion of Zic2 (K) and repression of N-tubulin (L). (M,O,P) Embryos injected with VP16-Xsix3 display reduction of the Xash3 (M), Zic2 (O) and Xhairy2 (P) expression domains. (J,N) Arrows indicate the anterior boundaries of Xngnr1 in the injected side of the embryo. (A-P) Frontal views, dorsal towards the top. Red staining in B,C,F-P and turquoise staining in A,E represent expression of the co-injected lacZ lineage tracer. The injected side of the embryos (to the left of dotted lines representing the midline) is indicated (inj). (H) White brackets indicate the anterior expression of Xhairy2 in Xsix3-injected (left) and control (right) sides.