Fig. 7. CM-Der can antagonize Nodal-mediated mesoderm induction. (A) In whole embryos, CM-der attenuates xnr2 overexpression phenotypes. One-cell embryos were injected at the animal pole with increasing doses of xnr2 mRNA (top row; xnr2 levels range from 1 to 10 pg). The overexpression phenotype is shown at stage 11 (left side of each panel) and stage 20 (right side of each panel). This overexpression phenotype is markedly decreased by co-injection of 3 ng of CM-der mRNA (bottom row). (B) In animal caps, CM-der antagonizes both xnr2-mediated mesoderm induction and the induction of other TGFß transcripts. Embryos were injected at the animal pole at the one-cell stage with increasing amounts of xnr2 mRNA (0.1, 1 and 10 pg) either alone or with 2 ng of CM-der mRNA. Co-injection of CM-der attenuates mesoderm induction by xnr2 (as indicated by xbra, gsc and chordin) and also retards the induction of multiple TGFß transcripts.