library_construction_protocol: Cells were harvested and fixed with BD fix buffer I (BD Biosciences) for 10 min at 37°C. Cells were stained with DAPI (1 ug/ml) for 1 h at RT to visualize G1 cells. 24 million G1 haploid cells were sorted using a BD FACSAria Fusion, followed by gDNA extraction. Library preparation as described in (Blomen et al., 2015).