|
||


* Department of Physics, Translational dynamics of chromatin in interphase nuclei of living Swiss 3T3 and HeLa cells was
studied using fluorescence microscopy and fluorescence recovery after photobleaching. Chromatin was
fluorescently labeled using dihydroethidium, a membrane-permeant derivative of ethidium bromide. After
labeling, a laser was used to bleach small (~0.4 µm radius) spots in the heterochromatin and euchromatin of
cells of both types. These spots were observed to persist
for >1 h, implying that interphase chromatin is immobile over distance scales
Northwestern School of Law, and § Department of Mathematics, Lewis & Clark College, Portland,
Oregon 97219; and
Biophysics Research Division and Department of Physics, University of Michigan, Ann Arbor, Michigan
48109
0.4 µm. Over very short
times (<1 s), a partial fluorescence recovery within the
spots was observed. This partial recovery is attributed
to independent dye motion, based on comparison with
results obtained using ethidium homodimer-1, which
binds essentially irreversibly to nucleic acids. The immobility observed here is consistent with chromosome
confinement to domains in interphase nuclei. This immobility may reflect motion-impeding steric interactions that arise in the highly concentrated nuclear milieu or outright attachment of the chromatin to
underlying nuclear substructures, such as nucleoli, the
nuclear lamina, or the nuclear matrix.
This article has been cited by other articles:
|
|