Fig. 4: FLIM-FRET mapping of genomic DNA compaction in HeLa cell nucleus.
From: Fluorescence lifetime imaging for studying DNA compaction and gene activities
The replicating cells were labeled in early and mid S-phase with AlexaFluor 546 (donor) and AlexaFluor 647 (acceptor) fluorophores correspondingly. a Representative images of AlexaFluor 546 lifetime distribution in the nucleus in the absence and in the presence of AlexaFluor 647. In the presence of acceptor, the fluorescence lifetime of the donor is shortened due to FRET (b). The FRET efficiency distribution in the cell nucleus calculated according to donor fluorophore lifetime distribution. Colormap was empirically defined from the FRET distribution histogram (shown on (d)). c Representative histograms of the donor lifetimes in the absence and in the presence of the acceptor. d FRET distributions histogram showing three populations (low, intermediate and high FRET), designated by corresponding colors. See Fig. S6 for additional examples
