Figure 6.

Immunostaining of the epichromatin epitope in tangential optical sections of nuclei from U2OS and HL-60/S4 cells. Mouse mAb PL2-6 staining is shown in red; DAPI in blue. (A) presents tangential sections of nuclei within intact cells. The top row of three images displays sections of U2OS cells; the second row is from HL-60/S4 cells. (B) shows central and tangential sections of isolated HL-60/S4 cell nuclei, washed in different buffers prior to fixation and immunostaining. In the top row, the isolated nucleus was washed in 1.5 mM MgCl₂, 0.2 mM EGTA, 50 mM HEPES (pH 7.0); bottom row, washed in 0.2 mM EDTA, 0.2 mM EGTA, 50 mM HEPES (pH 7.0). Each image is a single deconvolved optical slice. In order to visualize the low amount of epichromatin immunofluorescence at the tangent of the NE, the brightness of the PL2-6 red signal was greatly increased. Bar equals 10 µm.