Fig. 5. Dpp signaling limits the duration of br expression in the roof cells. (A) Schematic of the dynamics of br levels in the roof cells in the wild type (dark gray). We predicted that the pulse-like dynamics of br expression in the roof cells should become sustained in the absence of Dpp signaling (light gray). (B) Uniform expression of Dad, the inhibitory Smad, changes the spatial pattern of Br protein: Br is ectopically expressed in the anterior cells. (C) At the same time, the duration of br expression in the roof cells is increased, compared with the wild-type pattern of br expression (Fig. 4G). This agrees with the schematic prediction in Fig. 5A. (D,E) Egg chambers with uniformly inhibited Dpp signaling. (D) Changes in the spatial pattern of Br in the anterior cells generate a predictable change in the expression of rho, which was previously shown to be repressed by Br. (E) Schematic of rho (blue) and Br (red) patterns. (F) Patterning defects in egg chambers with uniformly inhibited Dpp signaling lead to defects in eggshell morphology: EM image of Dad overexpression eggshell shows flat dorsal appendages and reduced operculum size. (G) Wild-type rho expression; (H) schematic of wild-type rho (blue) and Br (red) patterns; (I) wild-type eggshell morphology. In B,C,D,G anterior is to the left; the dorsal midline is marked by an arrowhead; yellow dashed lines mark the anterior boundary of the oocyte. DA, dorsal appendages; op, operculum.