Fig. 5. Downregulation of Ras-dva functioning by the anti-Ras-dva morpholino or Ras-dva dominant-negative mutant, DN-Ras-dvaT22N, leads to an inhibition of anterior ectoderm markers expression. (A,B) The expression of the neural crest markers Sox9 and Slug is inhibited on the side of embryos microinjected with DN-Ras-dvaT22N mRNA. (C) By contrast, the microinjection of DN-Ras-dvaT22N mRNA resulted in a broadening of the expression domain of the neural border marker Msx1. (D) No effect on the expression of posterior neural marker HoxB9 was observed on the side microinjected with DN-Ras-dvaT22N mRNA. (E-J) The expression of markers of the neural plate (G, Otx2; H, Pax6), the anterior neural ridge (E, BF-1), the cranial placodes (G, Otx2;H, Pax6; F, Xag2) and the neural crest (J, Slug; I, Sox9) is inhibited on the side of embryos microinjected with the anti-Ras-dva morpholino. (K,L) Rescue of anti-Ras-dvaMO effects by co-injection of synthetic Ras-dva mRNA. The inhibited expression of the Slug marker, caused by a break of endogenous Ras-dva mRNA translation (K), can be restored by co-injection of a synthetic Ras-dva construct lacking the MO binding site (L). This result confirms the specificity of anti-Ras-dva MO effects. All embryos are shown from the anterior, dorsal side upwards. The `primed' counterpart pictures show the location of progenies of the microinjected blastomeres labeled by FLD tracer.