Fig. 2

Interaction between the Wnt3a/8 signaling and the ventrally expressed homeobox genes vox, vent, and ved for restriction of the dorsal organizer domain. (A) Expression of organizer genes in the wnt3a/wnt8 morphant embryos. The embryos received 4.2 ng each of wnt3aMO, wnt8-1MO, and wnt8-2MO (wnt3a/8MO, wnt3a/wnt8 morphant embryos) and were fixed at the shield stage. The expression of goosecoid (gsc), floating head (flh), and chordino (din) was expanded ventrally in the wnt3a/wnt8 morphant embryos compared with wild-type embryos (wt) or embryos receiving an injection of wnt3aMO (4.2 ng) alone (data not shown). In contrast, the expression of dickkopf1 (dkk1) was strongly reduced in the wnt3a/wnt8 morphant embryos. a–c, e–f animal pole views with dorsal to the right. d,h, Dorsal views. (B) Expression of vox and ved in the wnt3a/wnt8 morphant embryos, and expression of wnt3a and wnt8 in the vox/vent/ved morphant embryos. The vox/vent/ved triple morphant embryos were prepared by injecting 0.3 ng each of voxMO, ventMO, and vedMO, as published previously (Shimizu et al., 2002). a, b, e, f, shield stage, animal pole views with dorsal to the right. c, d, g, h, 80% epiboly stage, lateral views with dorsal to the right. Arrowheads indicate the dorsal limit of the vox and ved expression. The expression of vox and ved was reduced on the dorsal side in the wnt3a/wnt8 morphant embryos. The expression of wnt3a and wnt8 in the blastoderm margin was reduced in the vox/vent/ved morphant embryos. (C) Ved is epistatic to the Wnt3a/Wnt8 signaling. ved RNA (100 pg) was injected alone (b) or with wnt3aMO and wnt8MOs (c). The co-injection of ved RNA suppressed the head enlargement but did not suppress the reduction in posterior body observed in the wnt3a/wnt8 morphant embryos.