Figure 3. Effects of the intestinal stem cell (ISC)/enteroblast (EB)-specific knockdown of ATM or ATR on activation of the DNA damage response (DDR) with age.

(A) Effects of the ISC/EB-specific knockdown of ATM, ATR, or both on the age-induced increase of pS/TQ signals. The gut specimens of esg^ts>GFP, esg^ts>GFP+ATMi+ATRi, esg^ts>GFP+ATMi, and esg^ts>GFP+ATRi flies were cultured at 27 °C for 3 weeks, and were labeled with anti-pS/TQ (red) and anti-GFP (green) antibodies and 4′,6-diamidino-2-phenylindole (DAPI, blue). (B) Effects of the ISC/EB-specific knockdown of ATM, ATR, or both on the age-induced increase of γH2AvD signals. The gut specimens of esg^ts>GFP, esg^ts>GFP+ATMi+ATRi, esg^ts>GFP+ATMi, and esg^ts>GFP+ATRi flies were cultured at 27 °C for 3 weeks, and were labeled with anti-γH2AvD (red) and anti-GFP (green) antibodies and 4′,6-diamidino-2-phenylindole (DAPI, blue). Arrows indicate esg⁺ small cells. The original magnification is 400×.