Fig. 4.

Increased reactivity of antibodies to the SIRT7 C-terminal region occurs before, and independently of, onset of rDNA transcription. (A) Surrounded mitosis stages (M, T, T') of synchronized HeLa cells were determined on Z projections of focal planes by DAPI staining (a,e). SIRT7 and rDNA transcription sites were detected in fixed cells using respectively anti-SIRT7-C-terminal (b,f) and anti-BrdU (c,g) antibodies. Red and green labelings were merged (d,h). (B) Immunodetection of SIRT7 (c,h) and rDNA transcription sites (d,i) was performed in early G1 fixed cells in the absence (a-e) or presence (f-j) of AMD (0.1 μg/ml for 2 hours). Early G1 cells (arrows) were identified by phase-contrast (a,f) and DAPI staining (b,g). Arrowheads indicate metaphase cells. Immunofluorescence labelings were merged (e,j). Bars, 10 μm.