The ATM Signaling Cascade Promotes Recombination-Dependent Pachytene Arrest in Mouse Spermatocytes
Fig 1
Trip13mod/mod spermatocytes activate a recombination-dependent arrest at pachynema.
(A) Apoptotic Trip13mod/mod spermatocyte showing the axial element protein SYCP3 (green), TUNEL (green), mid/late pachytene stage marker H1t (blue) and γH2AX staining (red). Absence of H1t staining (blue) in the TUNEL-positive cell indicates that this is an early pachytene stage spermatocyte. (B) TUNEL staining appears as pan-nuclear labelling that overlaps all chromatin, which is observed in only a fraction of the analysed cells (asterisk shows an adjacent TUNEL-negative cell). (C) γH2AX localizes to the sex body (arrow) and unrepaired breaks (arrowheads). (D) Number of autosomal γH2AX patches (similar to arrowheads in (C)) counted in H1t-negative (early) and H1t-positive (mid/late) pachytene and diplotene cells from animals of the indicated genotypes. Means are indicated with horizontal lines. N shows the total number of cells counted per each stage and genotype. Primary data are provided in S1 Dataset. (E-P) Representative cells from the indicated genotypes stained for H1t (blue), γH2AX (red) and SYCP3 (green). In Trip13mod/mod, mid/late pachytene cells have substantially fewer γH2AX patches than early pachytene spermatocytes. Bar in (C) represents 10 μm and applies to all panels.