Chromatin condensed domains revealed by AFM, and their transformation in mechanically deformed normal and malignant cell nuclei.

It has been generally accepted that heterochromatin is represented by a regular, dense and closed structure, while euchromatin is open and sparse. Recent evidence indicates that chromatin is comprised of irregular nucleosome clutches compacted within the nucleus. Transcriptional events transform the chromatin architecture, resulting in appearance of 100-300 nm nucleosomal aggregates.

Alterations in the chromatin packaging, driven by transcriptional activity, revealed by AFM.

Background: The gene expression differs in the nuclei of normal and malignant mammalian cells, and transcription is a critical initial step, which defines the difference. The mechanical properties of transcriptionally active chromatin are still poorly understood. Recently we have probed transcriptionally active chromatin of the nuclei subjected to mechanical stress, by Atomic Force Microscopy (AFM) [1].

Atomic force microscopy bending tests of a suspended rod-shaped object: Accounting for object fixing conditions.

The technique of atomic force microscopy (AFM) bending tests of a suspended nano-object (scroll, tube, rod) makes it possible to calculate the Young's modulus of the material it is made of based on experimental data. However, the calculation results involve a large error due to uncertain conditions (console or bridge) of fixing the test object. One of the ways to reduce this error is based on the theoretical consideration of consoles or bridges as beams with one or two ends resting on Winkler elastic foundations.

Thermal Treatment Impact on the Mechanical Properties of MgSiO(OH) Nanoscrolls.

A group of phyllosilicate nanoscrolls conjoins several hydrosilicate layered compounds with a size mismatch between octahedral and tetrahedral sheets. Among them, synthetic MgSiO(OH) chrysotile nanoscrolls (obtained via the hydrothermal method) possess high thermal stability and mechanical properties, making them prospective composite materials fillers. However, accurate determination of these nano-objects with Young's modulus remains challenging.

AFM imaging of the transcriptionally active chromatin in mammalian cells' nuclei.

Background: Nuclear rigidity is traditionally associated with lamina and densely packed heterochromatin. Actively transcribed DNA is thought to be less densely packed. Currently, approaches for direct measurements of the transcriptionally active chromatin rigidity are quite limited.