Dmem high glucose medium without phenol red

Growth plate biopsies were collected from the proximal tibia and distal femur of children undergoing epiphyseal surgery due to constitutional tall stature, as previously described^{26 (link)}. The main patient characteristics are summarized in Supplementary Table 2(S2). Right after collection, the biopsies were put in DMEM-high glucose medium without phenol red (Sigma-Aldrich) supplemented with 10 µg/ml gentamicin and kept on ice. Thereafter, the tissues were cut into thin slices (0.5–1 mm) and each piece was individually transferred into 24-well plates containing culture medium (DMEM-high glucose without phenol red supplemented with 10 µg/ml gentamicin, 50 µg/ml ascorbic acid, 1 mM beta-glycerophosphate, and 0.2% BSA) where the compound of interest was added. For each treatment group, up to 4 pieces were used and the experiment was terminated after 48 h of culture. After that, the biopsies were washed with PBS, fixed in 4% PFA for 24 h, decalcified in EDTA, and put in 70% ethanol until paraffin embedding and sectioning. Each biopsy piece was considered an individual observation.

HeLa cells stably transfected with GFP-tagged histone 2B were used for most experiments and were provided by Noriaki Shimizu (Graduate School of Integrated Sciences for Life, Hiroshima University, Japan). Transfection protocol and authentication of cell line was published before (Kanda et al. 1998 (link)). Cell culture was conducted at 37 °C and 5% CO₂ using DMEM High Glucose Medium without phenol red (Sigma–Aldrich) supplemented with 10% FCS (Merck), 2 mM L-glutamine (Sigma–Aldrich), 100 µg/ml streptomycin (Sigma–Aldrich), 100 U/ml penicillin (Sigma–Aldrich), 1 mM sodium pyruvate (Sigma–Aldrich) and 25 mM HEPES (Sigma–Aldrich). Vinblastine and doxorubicin (Teva) were dissolved in water and applied for 4 h, tBHP (Sigma–Aldrich) was dissolved in water as well and applied for 30 min. MMS (Sigma–Aldrich) was dissolved in DMSO and applied for 4 h. Radiation was conducted on a CP160 (Faxitron) on petri dishes using X-rays. Cytochalasin B (Sigma–Aldrich) was dissolved in DMSO and used alone or in combination with etoposide (Teva), that was dissolved in DMSO as well and applied for 3 h. Hydroxyurea (Sigma–Aldrich) was dissolved in water and applied for 72 h before imaging or for the whole observation period during live imaging.