Inhibition of endogenous β-Trcp function by β-TrcpΔF induces ectopic Xnr3 expression and dorsal axis duplication. (A) Ventral injection of β-TrcpΔF RNA induced Xnr3 expression as examined by whole-mount in situ hybridization. All panels shown were ventral injection except in the control panel (a) (no injection). RNA amount injected per embryo: 1 ng for β-Trcp or β-TrcpΔF each, 100 pg for β-catenin, and 500 pg for ΔNTCF. The numbers of embryos with ectopic Xnr3 expression were 0 of 10 (number of embryos examined) in a; 0 of 8 in b; 10 of 10 for β-catenin (at 500 pg RNA per embryo; data not shown); 0 of 10 in c; 7 of 10 in d; 8 of 8 for β-TrcpΔF (at 4 ng RNA per embryo; data not shown); 0 of 10 in e; and 0 of 10 in f. (B and C) Axis duplication by β-TrcpΔF or β-catenin plus β-TrcpΔF. All shown were ventral injection except the control with no injection. Partial, partial axis duplication, defined as lacking eyes and other anterior structures in the duplicated axis. Full, complete axis duplication, defined as having eyes and other anterior structures in the duplicated axis. Number of injected embryos are indicated above each bar. RNA injected per embryo: β-catenin, 100 pg; β-TrcpΔF, 1 ng; GSK-3β, 1 ng; ΔNTCF, 500 pg.