Stage specific HiC in mouse meiosis
Mice were euthanized and testes were retrieved. The testes were first fixed with 1% formaldehyde for 10 minutes at room temperature.  Formaldehyde reaction was quenched by 0.125 M glycine. After two times of PBS wash, testes were first fixed with 3mM disuccinimidyl glutarate (DSG) for 45 minutes at room temperature.  DSG was quenched by 0.125 M glycine and testes were homogenized to prepare cell suspension. The cell suspension was filtered by 70 m cell strainer, washed with 1X PBS (phosphate buffered saline) and then resuspended in nucleus extraction buffer (15 mM Tris-HCl pH 7.4, 0.34 M sucrose, 15 mM NaCl, 60 mM KCl, 0.2 mM EDTA (Ethylenediaminetetraacetic acid), 0.2 mM EGTA (ethylene glycol tetraacetic acid). Nuclei were extracted using a Dounce homogenizer, 100 strokes with the tight pestle, and repeated once. Nuclei were filtered through a 40-m cell strainer and resuspended in chilled PBTB buffer (1 PBS with 0.1% Triton X-100, 5% bovine serum albumin, and protease inhibitor). To purify the populations of interest, a combination of intranuclear markers were used (Figure S1). Micro-C was performed as described (Tsung-Han S. Hsieh et al., 2020) with minor modifications.