Fig. 3

Tailbud expression of caudal-related genes cdx1a and cdx4, but not bmps or cyclops is dependent on the Wnt3a/Wnt8 signaling. (A) Expression of bmp2 and bmp4 at the bud stage, and expression of cyclops (cyc) at the 80% epiboly stage in the wild-type (wt, a, b, c) and wnt3a/wnt8 morphant (wnt3a/8MO, d, e, f) embryos. Expression of bmp2b and bmp4 in the ventro-lateral domains but not in the tailbud was reduced in the wnt3a/wnt8 morphant embryos. Expression of cyc in the axial mesoderm was slightly expanded in the wnt3a/wnt8 morphant embryos. a, b, d, e, lateral views with dorsal to the right. c, f, dorsal views. (B) Expression of cdx1a and cdx4 in the wnt3a/wnt8 morphant embryos and dkk1 RNA (25 pg)-injected embryos, and in embryos misexpressing wnt3a. Expression of cdx1a and cdx4 was reduced in the wnt3a/wnt8 morphant embryos, compared with wild-type embryos, at the bud (a, d, h, k), 8-somite (13 hpf, b, e, i, l), and 17-somite (17 hpf, c, f, j, m) stages. Expression of cdx1a and cdx4 was also reduced in the dkk1 RNA-injected embryos at 17 hpf (g, n). Note that the expression of cdx4 in the posterior neuroectoderm (arrows) was less reduced than in the paraxial mesoderm (arrowheads) in the wnt3a/wnt8 morphant embryos. Ectopic expression of cdx1a and cdx4 was detected in the embryos injected with 6 pg of pCS2 + wnt3a plasmid DNA at the bud stage (o, p, arrows). a, d, h, k, o, p, lateral views with dorsal to the right. b, e, i, l, tailbud views. c, f, g, l, m, n, lateral views with anterior to the left.