Histone Tail Modifications of H3 and H4 during the Physarum polycephalum Cell Cycle

Problem statement: Histone modifications are required for chromatin activities and are believed to form an epigenetic code. However, the inheritance of the histone post-translational modifications remains unclear. Approach and Results: The aim of this study was to evaluate the histone modifications throughout the cell cycle and to determine whether the histone marks are transferred to daughter cells. Using the naturally synchronous model system Physarum polycephalum and Western blotting analyses, we showed that the histone modifications are not exclusive of the cell cycle stage. Importantly, we also demonstrated that during mitosis, a substantial fraction of the acetylation and the methylation marks of the histone H3 and H4 is removed. Conclusion: The results illustrate that a part of the histone modifications are displaced during mitosis and thus failed to exhibit an inheritance to daughter cells as proposed for the epigenetic marks.