Fig. 2.
The Torso pathway antagonizes nuclear localization of Dorsal. (A-M) Stage 5 embryos stained for Dl (green). (A-D) Confocal z-stack images of ventral views, with anterior towards the left. (I-L) High magnification views of posterior poles of embryos stained for Dl (green). (I′-L′) Embryos were also co-stained for Lamin (red), showing that images truly correspond to sagittal cross-sections. Scale bars: 50 μm. (A,E,I,I′) Wild-type embryos. Dl is nuclear on the ventral side and cytoplasmic dorsally. Note the declining nuclear Dl accumulation towards the termini. (B,F) DSor mutants. (J,J′) trunk mutants. Dl is nuclear at the termini. (C,G,K,K′) torY9 embryos. The domain of nuclear Dl retracts towards the center of the embryo. (D,H,L,L′) wntD mutants. Dl is nuclear at the poles, as in DSor and trunk embryos. (M-O) Quantification of nuclear Dl levels. (M) trunk mutant. The arrows indicate the clockwise, left-to-right direction of quantitative measurements of levels of nuclear Dl, presented in the graphs. (E-M) Embryos are oriented with anterior to the left and dorsal side upwards. (N,O) Quantifying nuclear Dl gradients in wild-type and mutant embryos. Solid line designates the average gradient; error bars indicate s.e.m. Levels of nuclear Dl are significantly higher at the anterior and the posterior poles (black arrows) of trunk (N; blue line; n=20 embryos) and wntD (O; blue line; n=27 embryos) mutants, compared with wild-type embryos (red lines; n=27 and 22 embryos, respectively), suggesting that Torso-induced WntD antagonizes nuclear accumulation of Dl at the termini.