Immunofluorescent staining
Oocytes and embryos were fixed in PBS-buffered 4% paraformaldehyde (PFA) for 30 min, followed by permeabilization with 0.1% Triton X-100. After blocking with 1% bovine serum albumin (BSA) for 1 h, cells were incubated with primary antibodies diluted in blocking solution at 4°C overnight. After 3 times washes with PBST, cells were incubated with secondary antibodies at room temperature for 1 h, and then stained with DAPI for 10 min. Finally, the oocytes were mounted on glass slides and examined using a Zeiss LSM 880 laser scanning confocal microscope.
To detect DNA damage, the primary rabbit anti-γH2AX antibody (Cell Signaling,5438S, 1:200) with a corresponding secondary antibody conjugated with Alexa 488 goat anti-rabbit (Invitrogen, A48282, 1:1000) were used. To investigate the histone modification, rabbit anti-H3K27me3 antibody (Cell Signaling, 9733S, 1:200) with a corresponding secondary antibody conjugated with Alexa 488 goat anti-rabbit (Invitrogen, A48282, 1:1000) were used.