Fig. 5

nlk MO enhances the mesoderm defect of wnt8 MOs. (A,B,C) Wild type, (D,E,F) wnt8 MOs, (G,H,I) nlk MO and (J,K,L) nlk MO/wnt8 MOs. A,D,G,J were stained for tbx6 at 90% epiboly (vegetal view; dorsal to the top). B,E,H,K were stained with a mix of opl, pax2, krox20 and myod at 6 to 7 somites (dorsal view; bars indicate the extent of opl expression). C,F,I,L were left to develop to 24 hpf (lateral view). tbx6 expression is reduced in wnt8 (D) and nlk (G) compared with wild type (A), whereas nlk/wnt8 morphants have a dramatic reduction in tbx6 (J; double-headed arrows indicate dorsal region of margin where tbx6 is excluded). wnt8 MO embryos have a greatly expanded opl domain, and a slightly wider notochord (E; notochord domain delineated by longitudinal stripes of adaxial myod expression), reflecting the defects in AP patenting of the neuroectoderm and in DV patterning in the mesoderm, characteristic of wnt8 morphants. nlk morphants (H) are slightly shorter than wild type, but have no significant defects in neuroectoderm or mesoderm patterning. nlk/wnt8 morphants (K) are dramatically shortened, with significantly broadened expression of neural markers, reflecting increased dorsalization of the embryos. Only a few trunk somites are formed, and tail formation does not occur. nlk/wnt8 morphants at 24 hpf (L) are significantly shorter than wild type (C), wnt8 MO (F) or nlk MO (I), and show a dorsal curvature of the tail characteristic of severely dorsalized embryos.