Fig. 4. DN-Wnt3a can rescue the effects of Wnt3a on cell movement patterns in vivo. (A) DN-Wnt3a-GFP-(green) and RFP-(red) expressing HH3 streak cells grafted into a stage-matched host displayed normal migration patterns in control embryos. (B) A graft of Wnt3a-expressing cells affected GFP- and RFP-labelled cells at different anterior-posterior levels and caused cells to take a wider path. (C) The movement trajectories of cells expressing DN-Wnt3a-GFP were restored to normal in the presence of Wnt3a-expressing cells but RFP-transfected cells still displayed wider migration trajectories. (A-C) Panels on the left show GFP and RFP fluorescence with bright field at the start point of imaging. The two central panels show dark-field images at the time points indicated. Panels on the right show fluorescence with bright field at the end of imaging. Vertical white lines indicate the axial midline; angled white lines indicate the main trajectory of cells leaving the streak. Heart-forming regions at HH8 [based on Stalsberg and DeHaan (Stalsberg and DeHaan, 1969)] are outlined in white. Scale bar in A: 500 µm.