Pol I transcription switches off and on during mitosis. (A) Live-cell imaging snapshots to show dynamic changes of 5.8S rRNA labeled by stdMCP-tdTomato and H2B-GFP during mitosis. “0 min” indicates the time of nuclear membrane rupture. See Video 2 for dynamics. The white circle highlights the area where the stdMCP-tdTomato is located, which represents the outline of the nucleus (before nuclear membrane rupture) or the cell (after nuclear membrane rupture). Arrows point to visible MS2-tagged rRNAs. (B) Broken line diagram illustrating the dynamic change of rRNA synthesis during the cell cycle. Each line represents a single cell (n = 13).