Visualization of Elasticity Distribution of Single Human Chromosomes by Scanning Probe Microscopy

We succeeded in visualizing the spatial distribution of the local elasticity of mitotic human chromosomes in a liquid environment using scanning probe microscopy (SPM). Force-versus-indentation curves (force curves) were collected over an entire single chromosome. To estimate the local elasticity of thin chromosomes from the force curves, we examined the validity of a previously proposed model that takes into account the effect of the finite thickness of samples on the estimation of the local elasticity. The force curves obtained are well represented by the model within a small indentation range. The elasticity obtained is independent of the indentation within an indentation range of 100 nm. Such fitting procedures for the force curves collected are carried out over the entire chromosome, and the elasticity distribution of a single chromosome is visualized.