title: Viscoelasticity of model interphase chromosomes.
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 the 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 temporarily "caged" by chromatin spatial constraints, which thus form effective domains whose sizes match remarkably well with 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.
authors.affiliation: Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69634 Lyon Cedex 07, France.
authors.forename: Manon
authors.initials: M
authors.lastname: Valet
authors.affiliation: Sissa (Scuola Internazionale Superiore di Studi Avanzati), Via Bonomea 265, 34136 Trieste, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Rosa
mesh_terms: D000818:Animals; D002843:Chromatin / Q000737:chemistry*; D002875:Chromosomes / Q000737:chemistry*; D003198:Computer Simulation; D004058:Diffusion; D055119:Elastic Modulus; D007399:Interphase / Q000235:genetics; D008956:Models, Chemical; D008957:Models, Genetic; D056004:Molecular Dynamics Simulation; D009038:Motion; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D012212:Rheology; D012996:Solutions; D055682:Viscoelastic Substances / Q000737:chemistry*; D014783:Viscosity
chemical_list: D002843:Chromatin; D011108:Polymers; D012996:Solutions; D055682:Viscoelastic Substances