Neural Induction in Xenopus: Requirement for Ectodermal and Endomesodermal Signals via Chordin, Noggin, β-Catenin, and Cerberus
Figure 7
A Double-Assurance Mechanism in Xenopus Neural Induction That Requires Chordin and Cerberus
(A) A new Cer-MO is complementary to both Cer pseudoalleles, while two MOs reported by other authors (Hino et al. 2003; Silva et al. 2003) match only one allele, having three or four mismatches, respectively, with the other allele. The Cer-MO used in the present study inhibits head formation in intact embryos (data not shown), while the other two do not (Hino et al. 2003; Silva et al. 2003).
(B) Experimental procedure and cell lineages at 32-cell and early gastrula (stage 10.5) for dorsal-animal (FDA, green) and dorsal-vegetal (TRDA, red) blastomeres microinjected at the 8-cell stage.
(C and D) Uninjected embryos.
(E and F) Dorsal-animal injection with 8.5 ng of Chd-MO alone partially inhibited head formation; green fluorescence was seen in anterior CNS.
(G and H) Dorsal-vegetal injection with 17 ng of Cer-MO also inhibited brain formation partially; red fluorescence may be seen in anterior endomesoderm.
(I and J) Injection with 8.5 ng Chd-MO dorsal-animally and 17 ng Cer-MO dorsal-vegetally blocked brain formation, but not spinal cord and somites (histological sections not shown).