Temporal drift of nuclear structures in lifetime image during acquisition. (A) Lifetime images of a U2OS single nucleus expressing Cyclin T1 fused in frame to mTurquoise2 fluorescent protein (CT1-mT2) and RPB1 subunit of RNAPII fused in frame to Reach2 fluorescent protein (RPB1-Reach2). Images were generated from 420 TCSPC frames and postprocessed to keep the first 120, 220, or 320 frames as indicated in the figure. Pixels in the images were arbitrarily segmented below 3.67 ns and a 1-pixel sliding binning was operated. Alternatively, images were generated from the first 120 frames or the last 120 frames. (B) Green and red squares highlight clusters with different dynamics over the acquisition time. Extranuclear pixels were excluded from analysis. Scale bars, 2 μm. To see this figure in color, go online.