Figure 3.

Loss of rbf together with CycE and Stg prevents cell cycle exit and causes overproliferation of terminally differentiated cells. (A–G) GFP-marked rbf-null mutant clones expressing CycE and Stg were generated using the MARCM system and examined for ectopic S phases (BrdU; A) or mitoses (PH3; B, E, and F). Ectopic cell cycles are evident at high levels (mitotic index up to 20%) in wings (A, B, and F) and eyes (E; 15%) at all time points examined, including the latest time point, 60 h APF. Bulges and folding of adult cuticle are observed in regions of mutant clones in the thorax (C) and wing (D and inset). Eye (E) and wing (F) terminal differentiation structures such as lenses, bristles, and wing hairs are evident. A tangential section of a wing clone shows tissue folding caused by overproliferation (G). (H and I) GFP-marked rbf-null mutant clones expressing Stg were generated using the MARCM system and examined for ectopic mitoses at late stages up to 56 h APF (PH3; H and I; 48 h APF shown). At stages after 40 h APF, a few mitoses were evident in more proximal regions of some clones (H, arrowheads) but not in most clones in the wing (H, insets) or the eye (I, insets show a second example of a clone in the eye). (C, E″′, and F″) Yellow outlines indicate clone boundaries. DIC, differential interference contrast. Bars: (A, B, E, F, H, and I) 50 µm; (C) 100 µm; (D) 0.5 mm; (G) 20 µm.