Involvement of SSB and NAC in ribosomal biogenesis. (A, top) Expression of Rpl25-GFP in wt and mutant cells. NacΔ and nacΔssbΔ deletion strains show accumulation of the nuclear Rpl25-GFP signal. (bottom) The localization of Rpl25-GFP signal in cells was visualized by fluorescence and differential interference contrast (DIC) microscopy. (middle) DAPI was used to visualize nuclei. Bars, 2 µm. (B) SSB genetically interacts with Jjj1. The triple ssb1Δ ssb2Δ jjj1Δ mutants (clone #1; #2) carrying the wt versions of the SSB1 gene on a URA3-based plasmid were streaked on SC-URA and 5-FOA plates and incubated for 5 d at 30°C. The ssbΔ mutant carrying SSB1 wt gene on the plasmid and jjj1Δ mutant containing empty vector served as controls.