Fig. 5

Reduction of Med10 inhibits Nodal signaling. (A–H) Reduction of Med10 suppresses Nodal target-gene expression. MO1-Med10 (15 ng) was injected into embryos at the one-cell stage, and embryos were fixed at 30% epiboly and stained using in situ hybridization. Shown are animal pole views. Shown are nodal (cyclops) and ntl expression in MO1-Med10 injected (B,D) and control (A,C) embryos; and bon and cas expression in MO1-Med10 injected (F,H) and control (E,G) embryos. (I–L) Reduction of Med10 leads to an altered expression pattern of Nodal target genes. Embryos injected with MO1-Med10 (5 ng) at the one-cell stage were fixed at 75% epiboly and subject to in situ hybridization staining. Shown are lateral views with the animal pole up. Mesoendoderm cells, as stained by cas and fau, moved faster toward the animal pole in the med10 morphants (J,L), when compared with controls (I,K). (M–U) Reduction of Med10 suppresses Nodal-induced ectopic notochord formation. Single-cell injection of nodal (cyclops)/gfp mRNA (10 and 100 pg, respectively) at the 128-cell stage induced ectopic notochords in one-day old embryos (M), as confirmed by ntl staining (N). Ectopic ntl expression could be detected as early as 75% epiboly in nodal (cyclops)/gfp injected embryos (T), but not in embryos co-injected with MO1-Med10 (150 pg) (U) and control embryos (S). In addition, note the clustered and scattered expression of ectopic nodal (cyclops) in embryos injected with nodal (cyclops)/gfp and nodal (cyclops)/gfp/MO1-Med10, respectively (Q,R). (O) Quantification of Nodal-induced ectopic notochords. Data presented in (O) are the means ± SD from at least three independent experiments. Total embryos scored were 735, 140, and 183 for nodal (cyclops)/gfp, nodal (cyclops)/gfp/MO1-Med10 (10 pg/100 pg/150 pg), and nodal (cyclops)/gfp/Med10 mRNA (10 pg/100 pg/100 pg) injections, respectively. Arrows indicate ectopic notochord formation (M,N,T), and the arrowhead indicates ectopic nodal (cyclops) expression (Q).