LiveArt monitors the dynamic process of nucleolar segregation induced by Pol I transcriptional shut-down in interphase. (A) Snapshots of live-cell imaging of 3′-ETS-1 rRNA and nucleolar markers changes in the absence or presence of ActD. FC is labeled by GFP-RPA43 (green) and DFC is indicated by HaloTag-FBL (blue). Arrows point to the nucleolus that harbors active rRNA synthesis. The accumulation of MS2-tagged rRNAs indicated by stdMCP-tdTomato was highlighted with a white box. Insert magnification: 1.2×. See Videos 5 and 6 for dynamics. (B and C) Quantitative analysis of three representative cells (including one from A) showing dynamic changes in 3′-ETS-1 rRNA defined by the total intensity of stdMCP-tdTomato spots, as well as GFP-RPA43 or HaloTag-FBL by counting the mean fluorescence intensity of the regions (n ≥ 179) where they were enriched in the absence (B) or presence (C) of ActD. (D) Snapshots of live-cell imaging showing the dynamic changes of 5.8S rRNA and nucleolar markers in the absence or presence of ActD. Insert magnification: 0.54×. Arrows point to the nucleolus that harbors active rRNA synthesis. (E and F) Quantifications of three representative cells (including one from D) showing the dynamic change of 5.8S, GFP-RPA43, and HaloTag-FBL (analyzed in the same way as B and C, n ≥ 119) in the absence (E) or presence (F) of ActD. All images in Fig. 6 are maximum-intensity projections from z stacks. Nuclei are outlined with white circles. The data of RPA43 and FBL at each time point are represented as mean ± SEM. Scale bars, 5 µm.