Figure 2. Bcl-2-related Apoptosis of Photoreceptors Is Prevented in Phototransduction-deficient Rpe65^−/−/Gnat1^−/− Mice.

(A) TUNEL assay was performed in 6 month-old wt, Rpe65^−/− and Rpe65^−/−/Gnat1^−/− retina flatmounts (400×) labeled with TMR nucleotides to detect red fluorescence staining of apoptotic photoreceptor nuclei. Counterstaining with DAPI was performed to localize faced up photoreceptors. (B) Increase in the number of apoptotic cells relative to wt retinas was measured by counting TUNEL-positive nuclei. Double knock-out mice deficient for rod transducin were protected from phototransduction-induced apoptosis as compared in Rpe65-deficient mice. Data are the mean±SE of three independent experiments. * p<0.001 by ANOVA test for Rpe65^−/− versus wt and Rpe65^−/−/Gnat1^−/−