Dpb11 associates with chromatin-free anaphase bridges in mitotic cells. The localization of proteins of interest was determined in haploid cells during the exponential growth phase by fluorescence microscopy and differential interference contrast. Arrowheads mark bridges. (A) Dpb11 forms bridge-like structures in mitotic cells. Cells expressing Dpb11-YFP from the Tet-Off promoter (ML535-5D) were analyzed. (B) Dpb11 under the control of its native promoter also forms ultrafine anaphase bridges. Cells expressing Dpb11-YFP (ML253) from its native promoter were analyzed after Hoechst staining. (C) Dpb11 and Rfa1 colocalize at UFBs. Cells expressing Dpb11-YFP and Rfa1-CFP (SMG216-10A) were analyzed after Hoechst staining. (D) Dpb11 bridges colocalize with Top3 and Sgs1 bridges. Cells coexpressing Dpb11-CFP with Top3-YFP (SMG247-4A) or YFP-Sgs1 (SMG258-10A) were analyzed. (E) Dpb11 bridges rarely colocalize with chromatin-associated factors or rDNA-binding proteins. Cells expressing Dpb11-YFP and Rsc1-CFP (SMG220-15A), Nhp10-CFP (SMG221-15D), or Htz1-CFP (SMG219-5D), or cells (ML533) expressing Dpb11-YFP transformed with a plasmid expressing Nop1-CFP (pWJ1299) were analyzed. (F) Dpb11 bridges are predominantly Hoechst and chromatin negative. UFBs and chromatin bridges were counted as Dpb11-YFP bridges that do or do not colocalize with Hta1-CFP (VS23-1B), Htz1-CFP (SMG219-5D), or Hoechst (ML533 and ML253), respectively. Error bars represent 95% confidence intervals.