Fig. 4: Cell cycle sorting and colocalization between replication and transcription in U937-PR9 from STED images.
a Representative 3-color image including 2-color STED image of EdU-Alexa 594 (green) and Pol2-Atto647N (red) and confocal image of Picogreen (blue), in U937-PR9 cells. Scale bar 10 µm. b Scatter-plot of replication foci pixel density (ρRF) versus intensity (IRF): the gray dashed lines indicate the thresholds for separation into the 4 groups. c Representative 2-color STED images of replication (EdU) and transcription (Pol2) foci in U937-PR9 cells sorted in the four cell cycle groups (G1/G2, Early, Middle, Late). Scale bar 5 µm. d Colocalization fraction between replication and transcription extracted by STED-ICCS. (Early, f1 = 0.28 ± 0.02, mean ± s.e.m., n = 7 cells; Middle, f1 = 0.04 ± 0.01, mean ± s.e.m., n = 110 cells; Late, f1 = 0.03 ± 0.06, mean ± s.e.m., n = 2 cells). Mann–Whitney test was performed for statistical significance. e Schematic representation of the meaning of the ICCS colocalization fraction extracted from STED images, in relation to the distribution of the replication and transcription foci.
