Figure 4

DSBs are induced in osrecql4-2 mutants upon aphidicolin treatment. The comet assay, which can detect DNA breaks at the single cell level, detected DSBs under a neutral conditions protocol. Without aphidicolin treatment, no broken DNA fragments were observed in either wild-type or osrecql4 cells. Upon treatment with 5 mg/L aphidicolin for 60 min, broken DNA fragments were observed in osrecql4-2 cells under the fluorescent microscope (A) as summarized in (B) for osrecql4-2. The DSBs almost disappeared in osrecql4-2 after transferring to aphidicolin-free MS medium for 30 min. Immediately after treatment of aphidicolin; 15 aphidicolin-free MS medium for 15 min after treatment with aphidicolin; 30 aphidicolin-free MS medium for 30 min after treatment of aphidicolin.