A photoactivatable probe to investigate chromocenter properties.
(A) Heterochromatin staining using CP-SiR. (B) Heterochromatin
staining using CP-PA after photoactivation. PA-SiR after
405 nm photoactivation (magenta), HP1α-mEOs3.2 fluorescence
(cyan). (C) CP-SiR compared to CP-PA fluorescence
intensity after photoactivation in chromocenters (CC), compared to
nucleoli (NL). (D) Single-molecule tracks inside the nucleus, colored
by velocity. HP1α foci from the reference channel are shown
in gray, and approximate positions of nucleoli are depicted in dark
red. Fast-diffusing molecules are mostly found outside HP1α
foci. Molecules that get immobilized after photoactivation have stationary
tracks, colored in purple. (E) Diffusion coefficient estimates for
molecules within HP1α foci and in the rest of the nucleus are
based on analyzing jump distances in live cells (N = 8, 10 000 frames). Tracks recorded in different imaging
wells are distinguished by the circle and square symbols. Error bars
represent standard deviation. Scale bars: A, B = 10 μm, D = 3 μm, inset:
1 μm.