title: DNA relaxation dynamics as a probe for the intracellular environment.
abstract: Investigations into the biophysical properties of single molecules traditionally involve well defined in vitro systems where parameters such as solvent viscosity and applied forces are known a priori. These systems provide means to develop models describing the polymers response to a variety of conditions, including the entropically driven relaxation of a stretched biopolymer upon release of the tension inducing force. While these techniques have proven instrumental for recent advancements in the fields of polymer physics and biophysics, how applicable they are to life inside the cell remains poorly understood. Here we report an investigation of in vivo stretched polymer relaxation dynamics using chromatin relaxation following the breakage of a dicentric chromosome subjected to microtubule-based spindle forces. Additionally, we have developed an in vitro system used to verify the conformations observed during the in vivo relaxation, including the predicted but previously unidentified taut conformation. These observations motivate our use of existing polymer models to determine both the in vivo viscosity as seen by the relaxing chromatin and the tension force applied by the microtubule-based spindle in vivo. As a result, the technique described herein may be used as a biophysical strategy to probe the intranuclear environment.
authors.affiliation: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA. jfisher@cgr.harvard.edu
authors.forename: J K
authors.initials: JK
authors.lastname: Fisher
authors.forename: M
authors.initials: M
authors.lastname: Ballenger
authors.forename: E T
authors.initials: ET
authors.lastname: O'Brien
authors.forename: J
authors.initials: J
authors.lastname: Haase
authors.forename: R
authors.initials: R
authors.lastname: Superfine
authors.forename: K
authors.initials: K
authors.lastname: Bloom
mesh_terms: D015825:Chromosomes, Fungal / Q000737:chemistry; D004271:DNA, Fungal / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D004718:Saccharomycetales / Q000737:chemistry* / Q000166:cytology*; D008941:Spindle Apparatus; D014783:Viscosity
chemical_list: D004271:DNA, Fungal