Fig. 3. Notch is required in the follicle cells for the mitotic-to-endocycle transition. (A) Notch protein is observed in the apical surface of the follicle cell layer in wild-type egg chambers. (B) Cells in Notch clones (black, outlined by broken white line) have smaller nuclei than their wild-type neighbors. This most probably indicates lack of endocycles in the mutant clones. (C-E) Mitotic markers (PH3, CycB) are observed in cells in Notch mutant clones at stage 8-9, indicating a failure to enter the endocycle. (F) string expression can still be observed at stage 8 in egg chambers with Notch mutant clones. In this case, the mutant clone is unmarked. (G) Quantitation of the number of cells in Notch mutant clones (dark purple bar, the black clone in the figure is marked with an unbroken white line) compared with the sister clones (light purple bar, bright green in the figure marked with broken white line). The results are plotted as a function of sister clone size. (H) Ratio of the size of mutant clone per the size of sister clone in G plotted as a function of sister clone size. More cells are observed in the mutant than in sister clones (mean ratio=1.8). Importantly, the ratio does not change as a function of clone size, suggesting that the defect in Notch clones only occurred after the normal mitotic stage. Notch clones marked with broken lines in B-D and with an unbroken line in G.
