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Fig. 3. XtSulf1 enhances the axis-duplicating activity of Wnt11. (A–F) Whole mount in situ hybridisation shows that maternal expression of XtSulf1 co-localises with maternal Wnt11 in cleavage stage embryos (A, C, E, Wnt11; B, D, F, XtSulf1; all vegetal view). (G) Graph quantifying the frequency of double axes formed in embryos when increasing amounts XtSulf1 mRNA is co-injected with 600 pg of Wnt11 mRNA into a single ventral blastomere at the 4-cell stage (OB = open blastopore, DA = double axis, DH = double head). (H) Uninjected control X. laevis embryo. (I) Embryo injected with 600 pg of mRNA coding for XtWnt-11 into one ventral blastomere at the 4-cell stage. (J) Embryo injected with 600 pg of mRNA coding for XtSulf1 into one ventral blastomere at the 4-cell stage. (K–M) Embryos co-injected with 600 pg of XtWnt-11 and 600 pg XtSulf1 into one ventral blastomere at the 4-cell stage show duplicated axes. (N–P) Embryos co-injected with 600 pg of XtWnt-11 and 4 ng of XtSulf1 into one ventral blastomere at the 4-cell stage show duplicated heads and gastrulation defects. (Q) Section through a control embryo. (R) Section though an embryo shown in K showing duplicated notochord (arrows) and neural tissue. (S–U) In situ hybridisation showing the expression of chordin in a control stage 10 embryo (S), or embryos co-injected with 600 pg of XtWnt-11 and 600 pg XtSulf1 into one ventral blastomere at the 4-cell stage (T, U) showing ectopic expression of chordin in the ventral marginal zone (arrows). (V–X) In situ hybridisation showing the expression of Xnr3 in a control stage 10 embryo (V), or embryos co-injected with 600 pg of XtWnt-11 and 600 pg XtSulf1 into one ventral blastomere at the 4-cell stage (W, X) showing ectopic expression of Xnr3 in the ventral marginal zone (arrows). (Y) Co-immunoprecipitation of Wnt11-HA with LRP6-myc is enhanced when XtSulf1 is also expressed in Xenopus embryos. |
