Scientists Measure DNA Loop Density in Living Cells for the First Time
Researchers at Skoltech and the University of Potsdam have developed a physical model that, for the first time, precisely measures how tightly DNA is packed inside the cell nucleus.
Chromosomes stretching up to two meters in length fit inside a tiny cell nucleus thanks to a complex folding system. A key role is played by the protein cohesin, which acts as a molecular motor and forms DNA loops. The researchers found that 60–70% of all DNA in a cell is contained within such loops, with a density of about six loops per million base pairs. The model also separates the actual structure of chromosomes from distortions introduced by the widely used Hi-C experimental method.
The theory has been tested on more than 30 datasets from human and mouse cells. The results were published in the journal Proceedings of the National Academy of Sciences, and the code used for data analysis has been made publicly available.
