Centromeres and Telomeres as Rheological Probes of the Human Nucleus

The nucleus of eukaryotic cells stores genetic information in chromatin, the functional form of
DNA in cells. Chromatin loci have been observed to exhibit anomalous motion that is often
ascribed to the viscoelastic nature of the chromatin, transient interactions of DNA-associated
proteins and/or physical obstructions [1,2]. However, a direct link between motion of a chromatin locus
and the rheology of its local environment is missing. In this work, we investigate
dynamics of specific genomic loci, centromeres and telomeres, the centers and ends of the
linear interphase chromosomes, respectively, in the context of their local rheological
environment. Using simultaneous two-color spinning disc confocal microscopy combined with
recently developed machine-learning-assisted tracking algorithms [3], we monitor the motion of
telomeres and centromeres in live human cells and extract the rheological properties of their
surrounding environment, mapping the chromatin rheology across the cell nucleus.

[1] Levi et al, Biophys. J.. 2005
[2] Bronstein et al, Phys. Rev. Lett., 2009
[3] Eaton and Zidovska, Biophys.l J.. 2019