Fig. 3. Syce1^POF/POF oocytes fail to synapse and do not properly repair DSBs.

(A) Double immunolabeling of oocyte spreads from WT and Syce1^POF/POF mice with SYCP3 (red) and SYCP1 (green). Syce1^POF/POF oocytes became arrested in a zygotene-like stage where AEs remain unsynapsed and unaligned, with reduced levels of SYCP1. (B to D) Double immunolabeling of oocyte spreads with SYCP3 (red) and the CE proteins (green). Syce1^POF/POF zygotene-like oocytes showed reduced SYCE3 signal (B) and a complete absence of (C) SYCE1 and (D) SIX6OS1 from the AEs. IP, immunoprecipitation. (E) Double immunostaining of spread preparations of WT pachytene and Syce1^POF/POF zygotene-like oocytes with γ-H2AX (green) and SYCP3 (red). In Syce1^POF/POF oocytes, the levels of γ-H2AX increased and were more restricted to AEs in comparison with WT pachytene cells. (F to G) Double immunolabeling of (F) RAD51 or (G) DMC1 (green) and SYCP3 (red), showing higher numbers of foci in AEs from mutant oocytes. (H) Labeling of MLH1 (green) and SYCP3 (red). MLH1 foci are absent from the AEs of Syce1^POF/POF oocytes. Fluorescence intensity levels (A, B, and E) and number of foci (F and G) from WT and Syce1^POF/POF zygotene-like oocytes are quantified in the right-hand plots. Welch’s t test analysis: ***P < 0.0001. Scale bars, 10 μm.