Join Professor Gijs Wuite of the Vrije Universiteit Amsterdam for a Force Talk entitled "Elucidating the mechanics and structure of whole mitotic chromosomes".

Abstract

The DNA in eukaryotes is organised into linear chromosomes. These structures are highly dynamic throughout the cell cycle, and undergo dramatic compaction during mitosis to adopt the characteristic "X-shape". This metamorphosis is driven mainly by the combined action of condensins and topoisomerase IIα. Yet there is little known about the structural organization and mechanics of a mitotic chromosome. Here we introduce a workflow to investigate the organization of human chromosomes based on optical trapping and manipulation. This allows high-resolution force measurements and fluorescence visualization of native metaphase chromosomes to be conducted under tightly controlled experimental conditions. We have used this method to extensively characterize chromosome mechanics and structure.

Next, we employ AFM to study the structure of human metaphase chromosomes in a liquid environment that closely resembles their physiological conditions, without the use of fixation agents and enzymatic treatments. Our analysis reveals the finer details of the unperturbed chromosome structure, shedding light on the organization of the chromatin fiber network and testing its stability against changes in the environment ionic conditions. With AFM-based Force Spectroscopy we also probe the response of mitotic chromosomes to nanoscale deformations in the presence and absence of specific SMC proteinsthereby providing new insights into their contribution to the chromosome structural stability.

The methods described here open the door to a wide array of investigations into the structure and dynamics of both normal and disease-associated chromosomes.

How to join:

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