Figure 7.

Condensin maintains rDNA stability during transcriptional repression. (A) rpa190-1/3 mutations cause fragmented nucleolus phenotype. Early log-phase WT and rpa190-1/3 cells were shifted from 23 to 37°C in YPD for different times. Merged images of the nucleolus with the nucleus at 5 h are shown. Images of other time points and a color version of this figure are available at The EMBO Journal Online. (B) rpa190-1/3 mutations cause accumulation of cells with rDNA distributed throughout the entire nucleus. rpa190-1/3 cells were incubated at 37°C for 5 h and then analyzed for the nucleolar and rDNA structures by IF and FISH, respectively. Typical images of cells containing fragmented nucleolus or high levels of ERCs are shown. A color version of this figure is available at The EMBO Journal Online. (C) Rapamycin treatment suppresses the ERC formation in Pol I mutants. Early log-phase WT and rpa190-1/3 cells were shifted from 23 to 37°C for 2.5 h to inactivate Pol I, followed by incubation with or without rapamycin for different times. rDNA was analyzed by FISH. The upper panel shows the experimental strategy. Boxed cells were enlarged for better visualization. Images of other time points and a color version of this figure are available at The EMBO Journal Online. (D) Condensin is required for suppression of ERC formation in Pol I mutant in the presence of rapamycin. Single mutant (rpa190-1 YCS4) and double mutant (rpa190-1 ycs4-2) were shifted from 23 to 37°C for 2.5 h to inactivate Pol I and condensin, followed by incubation with or without rapamycin for 3 h. Merged images of the nucleolus with the nucleus are shown. A color version of this figure is available at The EMBO Journal Online.