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Material properties of the genome are critical for its proper function and organization inside the cell nucleus. Chromatin, the functional form of DNA in cells, consists of DNA and associated proteins, forming long linear fibers in the interphase nucleus of eukaryotic cells. Traditionally, rheology of cellular components has been studied by tracking microparticles injected inside the cell [1]. Recently, we developed an injection-free noninvasive approach to study chromatin rheology using nuclear organelles as native probes [2]. Here, we show an alternative noninvasive experimental strategy using intrinsic dynamics to measure chromatin rheology across a large range of timescales, and elucidate the viscoelastic nature of chromatin in live cells. The measured rheology is captured by a surprisingly simple model whose few parameters have clear physical interpretations for this complex active material.
1. Wirtz, Annu. Rev. Biophys, 2009
2. Caragine et. al. Phys. Rev. Lett., 2018