Fig. 5.

Recombination and the DNA repair process are altered in 17.5-dpc HSF1-deficient oocytes. (A) Diagram illustrating MSH4-related functions and indicating endpoint analyses performed on meiotic prenatal oocytes. MSH4 is included in transformed nodules (TN) which emerge from early nodules (EN) and subsequently—for some of them—evolve as recombination nodules (RN) associated with MLH1 (41). MSH4 foci are analyzed in panels B, C, and D. DNA repair progression is assessed with γH2AX staining as the hallmark for DSB (see panels B and E). (B) SYCP3 (red), MSH4 (green), and γH2AX (blue) immunostaining performed on Hsf1^+/− (control) and Hsf1^−/− oocyte spreads at 17.5 dpc (n = 50 for each genotype). (C) The number of MSH4 foci calculated per oocyte was significantly different in Hsf1^−/− oocytes compared to that in Hsf1^+/− oocytes (number of foci, 96.5 ± 14 versus 270 ± 40, respectively). (D) SYCP3 (red) and MLH1 (green) immunostaining on pachytene oocytes showed that there was no difference between the number of late recombination nodules between Hsf1^−/− (24.61 ± 1.12 foci) and Hsf1^+/− (24.15 ± 1.46 foci) oocytes (n = 25). (E) The area covered by γH2AX staining was different in Hsf1^−/− oocytes from that in Hsf1^+/− oocytes (γH2AX area, 142 ± 11 versus 28.5 ± 3 μm²). **, P < 0.01; ***, P < 0.001.