Fig. 3.

Fig. 3.

Greb1 is required foraxial elongation. (A–C,A′–C′) Lateral views of zebrafish embryos at 24 hpf, showing: (A) wild-type chevrons of xirp2a expression and the tail region (bracketed); (B,C) posterior loss in M1 and M2 morphants. The tail regions that are truncated and contain disrupted somites are bracketed. (D–F,D′–F′): expression of myoD in control (MM, M1 and M2 morphants). (G,L) papc, (H,M) mespa, (I,N) mespb, (J,O) her1, (K,P) her7 (Q,R) and (Q′,R′) Ntl expression in the tail region of 15 hpf control and morphant embryos. (S) A tentative model for gene interactions between Greb1 and patterning genes. Anterior expression of Her7 restricts mespb expression to the posterior somite compartment, which, in turn, restricts myoD and papC expression to the anterior compartment. Continuous arrows indicate interactions shown by others as likely to be direct. Dashed arrows could be direct or indirect.