dASCIZ and Ctp are required for progression through late stages of mitosis. (A) Proportion of cells in wing imaginal discs at the indicated mitotic stages based on cell morphology and PH3 staining. Compared with the control, wings expressing dASCIZ RNAi contain more cells undergoing anaphase and fewer cells in prophase (n = 449 for control; n = 474 for dASCIZ RNAi). (B) Fraction of PH3-labeled cells at the indicated mitotic stages costained with anti-Geminin antibody. Cells in the PC of the wing disc expressing GAL4 control, dASCIZ RNAi, or Ctp RNAi were sorted into mitotic stages based on morphology and scored for positive staining with Geminin. While control cells degrade Geminin at the metaphase/anaphase transition, staining in cells expressing dASCIZ and Ctp RNAi is reduced during metaphase (P = 0.0036 for dASCIZ RNAi and P = 0.0108 for Ctp RNAi, n > 7), indicating that Geminin is degraded earlier than in control cells and suggesting that these cells spend longer in mitosis. (C–F) Wing imaginal discs stained with Peanut antibody, En–GAL4 expression in the PC is outlined in white. (C) En–GAL4/+ control, (D) En > dASCIZ RNAi, (E) En > Ctp RNAi, and (F) En > dASCIZ RNAi, UAS–Ctp. (G) PC/AC ratio of Peanut staining in the wing imaginal disc. Error bars represent SEM for n > 7. Ratio is unchanged for UAS–Ctp (P = 0.9699), reduced for dASCIZ RNAi (P = 0.0014), and reduced for Ctp RNAi (P = 0.0013). Coexpression of dASCIZ RNAi with UAS–Ctp improves the ratio compared to dASCIZ RNAi alone (P = 0.0064) back to control levels (P = 0.2050).