Figure 1. Activation of ban after clonal induction of cell death in wing discs.

The larvae were heat-shocked (hs) to induce FLP-mediated excision of intervening sequences to allow GAL4 expression from the actin promoter. After heat-shock, actin-GAL4 was kept repressed with tubulin-GAL80^ts to allow clones to form. A shift to 29°C inactivated GAL80 and de-repressed GAL4, which drove the expression of UAS-hid, UAS-rpr and the UAS-RFP clonal marker. (A, C, E) Wing discs from a control RFP only larva. (B, D, F) Wing discs from an RFP, hid, rpr larva. The discs were imaged live for RFP and GFP. (G) shows the timeline followed. GFP images in C and D were acquired and processed using identical parameters to allow comparison. RFP was weaker in Hid/Rpr clones than in control clones; therefore RFP images such as those in B were visualized with increased brightness. The mean GFP signal was quantified for each disc, normalized to the average for controls (RFP only) discs and shown on panels D and F. *p<0.001. ‘RFP’  =  hs-FLP/Y; GFP ban sensor/+;tub-GAL80^ts/Act>>GAL4, UAS-RFP. ‘RFP, Hid/Rpr’ carries the same transgenes and has UAS-hid, UAS-rpr instead of Y. ‘h’  =  hour or hours.