Fig. 1. Breakdown during mitosis and reformation of the Dorsal gradient during interphase. (A) Cross-sectional views of a live Drosophila embryo, showing the distribution of Dorsal-GFP from nuclear cycles 11 to 14; orientation is ventral down, dorsal up. (B) Saggital views, showing interphase nuclear cycle 13, mitosis (prophase) and interphase nuclear cycle 14; the orientation in all panels is ventral down, dorsal up. (C) A quantification of the relative nuclear fluorescence of one nucleus at a fixed position as a function of time from nuclear cycles 12 to 14. Nuclear fluorescence intensity was calculated as spot intensity within nuclei minus the spot intensity of the adjacent cytoplasm plotted against time in seconds. Relative periods of interphase and mitosis (shown by hatched bars) were determined by visualizing mitotic spindles that are readily apparent on the dorsal side via their transient interaction with Dorsal-GFP.