Fig. 1

A Second Zebrafish brachyury Gene

(A) Neighbor joining tree of vertebrate Brachyury proteins, with Ciona intestinalis (Ci) serving as the outgroup. Bootstrap percentages are shown for 1000 trials. The other organisms are human (Hs), mouse (Mm), chicken (Gg), Xenopus tropicalis (Xt), Xenopus laevis (Xl), fugu (Tr), stickleback (Ga), medaka (Ol), and zebrafish (Dr).

(B–J) Expression of bra from 50% epiboly to 24 hpf.

(B and C) At 50% epiboly, expression is restricted to the dorsal side of the margin (B) as shown by costaining with gsc (arrowhead) at shield stage (C).

(D and E) At 60% epiboly, expression encompasses the entire margin and the forming axial mesoderm.

(F) By bud stage, expression is present throughout the notochord (N) and in the bud.

(G) There is a brief period of expression in the ventral mesoderm around the eight-somite stage (arrow).

(H–J) Between 14 somites and 24 hpf, expression is restricted to the posterior notochord and the mesodermal precursors of the tailbud, as well as cells ventral to the posterior notochord (arrowhead).

Embryos are shown from an (B and C) animal view with dorsal to the right, (D) vegetal view with dorsal to the right, (E) dorsal view with animal pole to the top, (F) dorsal view with anterior to the left, (G) posterior view with dorsal to the top, and (H–J) lateral view with anterior to the left.