Fig. 3. Effects of Otx2 and Xanf1 over-expression on Ras-dva expression at the neurula stage (stage 14). (A,A') Microinjection of the Otx2 mRNA into the right side of the embryo results in lateral and ventral expansion (red arrow) of the Ras-dva expression area on this side. (B,B') Overexpression of Xanf1 leads to an inhibition of the Ras-dva expression (black arrows). (C,C') The dominant repressor version of Xanf1 (EnR-Xanf1) inhibits Ras-dva expression at the microinjected side (black arrows). (D,D') The dominant activator version of Xanf1 (VP16-Xanf1) induces expansion of the Ras-dva expression area at the microinjected side (red arrows). (E,E') The dexamethasone-inducible version of Otx2 (Otx2-BDGR) elicits lateral expansion (red arrows) of the Ras-dva expression area when protein synthesis was completely inhibited by cycloheximide and dexamethasone treatment. This indicates that Ras-dva is the direct target of Otx2 in cells of the anterior ectoderm. (F,F') No expansion of the Ras-dva expression domain is detected in embryos, microinjected with Otx2-BDGR and treated by the cycloheximide solution alone. (G,G') The dexamethasone-inducible version of activating Xanf1 variant (VP16-Xanf1-BDGR) stimulates lateral expansion (red arrow) of the Ras-dva expression area when protein synthesis was completely inhibited by cycloheximide and dexamethasone treatment. This indicates that Ras-dva is the direct target of Xanf1 in cells of the anterior ectoderm. (H,H') No expansion of the Ras-dva expression domain is detected in embryos microinjected with VP16-Xanf1-BDGR and treated by the cycloheximide solution alone.