Fig. 4

Maternal wnt8a supports the functions of zygotic wnt8a. (A) Phenotype of maternal-zygotic wnt8a mutant (MZwnt8a-/-) embryos at 30 hpf. Embryos were obtained by crossing wnt8aΔO1ΔO2/+ male fish and female fish with wnt8aΔO1ΔO2/ΔO1ΔO2 germ cells. Lateral view with anterior to the left. Approximately half of the embryos were predicted to be MZwnt8a-/- embryos, and the rest were Mwnt8a-/- embryos. The MZwnt8a-/- embryos were identified by genotyping. (B) Percentage of embryos showing the no-yolk extension phenotype (No-YE, left panel), and of No-YE embryos showing the antero-dorsalized phenotypes C1-3 (right panel, Fig. 2B). MZwnt8a showed more severe antero-dorsalized phenotypes than did zygotic (Z) wnt8a mutants (ΔO1ΔO2 in Fig. 2C). The proportions of C1-3 embryos were significantly different between the Zwnt8a and MZwnt8a mutants (chi-square test, P<0.001). (C) Expression of noto (shield-stage, a, b), tbx6l (60% epiboly, c, d), and otx2 (100% epiboly stage, e, f) in WT and MZwnt8a mutant embryos. Animal pole views with dorsal to the right (a, b). Lateral views with dorsal to the right (c-f). The lateral limits of noto expression are marked by arrows, the rostral and caudal limits of otx2 expression are marked by arrowheads, and the ventral limit of otx2 expression is marked by an asterisk. An expanded expression of noto, reduced expression of tbx6l, and expanded expression of otx2 were observed in approximately half of the MZ mutant embryos (noto, n=28/65; tbx6l, n=13/26; otx2, n=13/28), compared to WT embryos (normal expression of noto, n=30/30; tbx6l, n=20/20; otx2, n=26/26). Scale bars: 500 µm in A; 200 µm in C.