Figure 7. p53A and p53B have overlapping and distinct functions in germline genome integrity and the meiotic pachytene checkpoint.
(A-E’) Drosophila ovarioles of indicated genotypes were immunolabeled for γ-H2Av (red A-E) to detect DNA breaks and counterstained with the DNA dye DAPI (blue A’-E’). The ovarioles are shown with the anterior germarium to left (square bracket). Scale bars are 25 µm. (A”-E”) Quantification of percent of ovarioles with γ-H2Av-positive nurse cells (blue squares) and oocyte (red ovals) at different stages. Values are means of five biological replicates and >20 ovarioles with error bars representing S.E.M. Those values that had low variance have very small error bars that are not visible in the graphs. See Figure 6—figure supplement 1 for higher mag images of germaria, and Supplementary file 1 for p values. (F–K) p53A is required for activation of the pachytene checkpoint. (F–J) Oocyte nuclei from stage 3 to 4 egg chambers labeled with antibodies against synaptonemal protein C(3)G (red) and DNA dye DAPI (blue). (F) Wild type with spherical compact karyosome. (G) okraRU / okraAA with diffuse chromatin indicating activation of the pachytene checkpoint. (H) okraRU / okraAA; p535A-1-4 (A-B-) null with compact spherical karyosome. (I) okraRU / okraAA; p53A2.3 (A-B+) p53A mutant with spherical karyosome. (J) okraRU / okraAA; p53B41.5 (A+B-) with elliptical nucleus. Scale bars are 3 µm. (K) Quantification of karyosome formation. Data are means based on two biological replicates with ~30 nuclei per strain per replicate, with error bars representing S.E.M. * p < 0.05, ** p < 0.01, n.s. = not significant by unpaired Student’s t test.