Fig. 2. Higher-order nuclear structures in Rad51-overexpressing cells. (A) Immunofluorescence staining of growth-arrested TGR928.1-9 cells reveals discrete nuclear foci and higher-order structures of overexpressed Rad51 protein (green) in a high percentage of cells. Nuclei are counterstained with DAPI (blue). Bar, 10 µm. (B) Ultrathin cross (left-hand side) and longitudinal sections (right) of nuclear Rad51 structures in TGR928.1-9 nuclei after pre-embedding immunolabeling with anti-Rad51 antibodies and 12 nm colloidal gold. Bar, 100 nm.