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Scientists Discover That Chromosomes Are Fluid

The study found that chromosomes are fluid, almost liquid, outside of their division phases.

Chromosome manipulation in live cells indicates that they are fluid.

Researchers from CNRS, the Curie Institute, and Sorbonne University have successfully physically acted on chromosomes in live cells for the first time. They found that, outside of cell division phases, chromosomes are actually very fluid—almost liquid—by subjecting to different forces using magnets. The study was recently published in the prestigious journal Science.

When they are not in their division phases, chromosomes are fluid, though not quite liquid. This discovery was made possible by the first-ever direct mechanical manipulation of chromosomes in the nucleus of live cells.

Previously, chromosomes, which are extraordinarily long DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>DNA molecules, were represented as entangled like loose balls of yarn and creating a sort of gel. This new publication’s findings present a completely different picture. Chromosomes are fluid and free to move, unrestricted by the other parts that make up the nucleus and can reorganize themselves.

To reach these conclusions published in Science, scientists from CNRS, the Curie Institute, and Sorbonne University, working in the Nuclear Dynamics, Physical Chemistry and Cell Biology, and Cancer laboratories, in collaboration with scientists from the Massachusetts Institute of Technology, attached magnetic nanoparticles to a small portion of a chromosome in a living cell. Then, they stretched the chromosome, exerting different degrees of force, thanks to a micro-magnet outside the cell. Using this approach, the teams managed to measure the response of a chromosome to external forces, for the very first time in a living cell.

Through these experiments, the scientists were able to see that the range of forces exerted naturally in the nucleus – for example by enzymes replicating DNA – is sufficient to substantially alter the conformation of a chromosome. This major discovery, at the interface between physics and biology, changes the hitherto established representation of chromosomes. It also adds new elements to our understanding of biological processes, the biophysics of chromosomes, and the organization of the genome.

Reference: “Live-cell micromanipulation of a genomic locus reveals interphase chromatin mechanics” by  Veer I. P. Keizer, Simon Grosse-Holz, Maxime Woringer, Laura Zambon, Koceila Aizel, Maud Bongaerts, Fanny Delille, Lorena Kolar-Znika, Vittore F. Scolari, Sebastian Hoffmann, Edward J. Banigan, Leonid A. Mirny, Maxime Dahan, Daniele Fachinetti and Antoine Coulon, 28 July 2022, Science.
DOI: 10.1126/science.abi9810

Source: SciTechDaily