Figure 4

Genes important in notochord differentiation exhibit two types of regulatory pattern during chordamesoderm to mature NC transition. A-H: Expression of ntl is normal during early NC development (A-D) in treated embryos but fails to get downregulated during the chordamesoderm to mature NC transition step (E-H). (A, B: 7 hpf; C, D: 12 hpf; E-H 24 hpf.) This pattern of developmental arrest occurs in ehh (I, J), shh (L, K), col2α1 (M, N) and hsp47 (O, P) expression. Q-X: mRNA levels of fkd1 (Q, R), fkd4 (S, T), spondin2 (U, V) and mindin (W, X) however decreases normally upon chordamesoderm to mature NC transition. Notice the unchanged expression of marker genes in the floor plate (M-X) and in the hypochord (O, P, U-X) of U0126-treated embryos. Panels: A, C, E, G, I, K, M, O, Q, S, U, W: wild type. Panels: B, D, F, H, J, L, N, P, R, T, V, X: U0126-treated embryos.