Viscoelasticity of model interphase chromosomes
arXiv:1412.6225 · doi:10.1063/1.4903996
Abstract
We investigated the viscoelastic response of model interphase chromosomes by tracking the three-dimensional motion of hundreds of dispersed Brownian particles of sizes ranging from the thickness of the chromatin fiber up to slightly above the mesh size of the chromatin solution. In agreement with previous computational studies on polymer solutions and melts, we found that the large-time behaviour of diffusion coefficient and the experienced viscosity of moving particles as functions of particle size deviate from the traditional Stokes-Einstein relation, and agree with a recent scaling theory of diffusion of non-sticky particles in polymer solutions. Interestingly, we found that at short times large particles are temporary "caged" by chromatin spatial constraints, which thus form effective domains whose size match remarkably well recent experimental results for micro-tracers inside interphase nuclei. Finally, by employing a known mathematical relation between the time mean-square displacement of tracked particles and the complex shear modulus of the surrounding solution, we calculated the elastic and viscous moduli of interphase chromosomes.
10 pages, 6 figures, accepted for publication in Journal of Chemical Physics
References in corpus (7)
- From a melt of rings to chromosome territories: The role of topological constraints in genome folding
- Interaction potentials for soft and hard ellipsoids
- Ring polymers in the melt state: the physics of crumpling
- Direct conversion of rheological compliance measurements into storage and loss moduli
- Viscoelasticity and primitive path analysis of entangled polymer liquids: From f-actin to polyethylene
- Measuring storage and loss moduli using optical tweezers: broadband microrheology
- Colocalization of coregulated genes: a steered molecular dynamics study of human chromosome 19