Fig. 7. Br controls Dpp signaling in the follicle cells by regulating the expression of tkv. (A-D) Uniform expression of Br-Z1 isoform in the follicular epithelium leads to ectopic expression of tkv and Dpp signaling. (A-C) Br (A) and P-Mad (B) patterns in a stage 12 egg chamber overexpressing Br-Z1. P-Mad signal is detected in the midline and anterior follicle cells, where it is absent in the wild-type egg chamber at this stage. The image in C is a merge of Br (red) and P-Mad (green) patterns. (D) Overexpression of the Br-Z1 isoform generates ectopic expression of tkv: tkv is expressed in the dorsal midline (denoted by the arrowhead), where it is repressed in the wild type (see also Fig. S3 in the supplementary material). (E-K) Clones of br^- cells (marked by an arrow) generate defects in the spatial patterns of Dpp signaling and tkv expression. The arrowhead marks the dorsal midline. (E-J) P-Mad pattern (red) in mosaic epithelial layers with the GFP-marked clones of br^- cells. (K) Defective pattern of tkv (denoted by the arrow) in the egg chamber with a clone of br^- cells. Dorsal view; the arrowhead marks the midline. (L) Model summarizing the results of experiments in A-K: Br regulates tkv, which is essential for Dpp signaling. (M) ESEM image of the eggshell morphology induced by the overexpression of the Br-Z1 isoform.