Fig. 2: Broadband microrheology of chromosomes.

a Schematic of microrheology experimental procedure. Dashed lines represent data at a force-loading rate of 0.2 μm/s and solid lines for 100 μm/s. Data in purple were analysed to provide broadband mechanical response. b Schematic representation of the tweezer and chromosome positions from (a) c Opposing forces experienced at bead handles (one shown) in the non-equilibrium state. d Zoomed-in sub-region of the analysed force at one bead and chromosome extension data. e Complex stiffness \({\kappa }^{*}(\omega )\) with frequency (bottom axis in black) and lag time \({\tau}\) (top axis in green) from broadband microrheology (BM) of WT chromosomes at 100 μm/s (median and 95% CI; n = 14 chromosomes), highlighting regions of viscous reorganisation and gel-like behaviour. Data in blue are the viscous modulus \({\kappa} ^{\prime \prime }(\omega )\) and in red are the elastic modulus \({\kappa} ^{\prime }(\omega )\). f \({\kappa }{*}(\omega )\) at 0.2 μm/s force-loading rate (median and 95% CI; n = 15 chromosomes) of WT chromosomes. e and f are both overlaid with oscillatory microrheology (OM) data from Meijering et al. (2022)^40,74. Schematics shown are not to scale. Data are provided in a Source Data file.