Aneuploidy promotes dysplasia. (A) Scheme illustrating temperature shifts performed in control and mad2RNAi flies. (B) Example of a 20-d-old control intestine subjected to temperature shifts as described in A (5 d recovery). In the majority of intestines, no GFP-positive cells could be detected (GAL4-UAS OFF). Only in a very small percentage of intestines could a couple of GFP-positive cells sometimes be detected (yellow arrow; inset B1). Cells undergoing proliferation were labeled with pH3 (white circle; inset B1), and cell nuclei with DAPI. (C) Example of a mad2RNAi intestine after 5 d recovery as described in A. (D and E) Intestines from control and mad2RNAi after 10 d recovery. (F) Quantification of mitotic cells before and during recovery. (G) 20-d-old control intestine where ISCs and EBs are marked based on esg expression (green). EEs can be identified by expression of Pros (nuclear red). Arm marks cells membrane, and DAPI marks cell nuclei. (H) Example of an intestine where RNAi construct against cenp-meta was expressed under the control of the esgGAL4 driver during the first 20 d of the adult. (I) Example of a 20-d-old intestine where the protein SAK was constitutively overexpressed (OE). (J and K) Quantification of the percentage of ISCs/EBs (GFP positive) per total cell number or EEs (Pros positive) in situations G–I. Control data are the same as shown in Fig. 3. Tukey boxplots. n (intestines) = 21 flies for control; n (intestines) = 32 flies for cenp-metaRNAi; n (intestines) = 8 for SAK overexpression. (L–N) Same genetic conditions and time point as described for G–I but stained for pH3. Bars: 40 µm (main images); 20 µm (insets). White circles and yellow arrows show pH3-positive cells. (O) Number of mitotic cells present in the first two fields of view of the posterior midgut after the pyloric ring (40× objective) from L–N. Mean ± SD. *, P < 0.05; **, P < 0.01; ***, P < 0.0001; ****, P < 0.0001; Mann–Whitney U test. n (intestines) = 39 flies for control (control data are the same as in Fig. 3); n (intestines) = 18 flies for cenp-metaRNAi; n (intestines) = 24 for SAK overexpression.