Measuring the Mechanical Properties of Chromosomes

Every time a cell divides, it must package two metres of DNA into compact, X-shaped chromosomes that can withstand the physical forces of being pulled apart. This project uses optical tweezers—focused laser beams that can trap and stretch microscopic objects—to measure exactly how stiff, elastic, and strong those chromosomes are. The problem is that while scientists know a lot about the chemical composition of chromosomes, they know very little about their mechanical properties. Without that knowledge, it is impossible to understand why chromosomes sometimes fail to separate correctly during cell division, a failure that can lead to cancer or developmental disorders. This is fundamental science. The immediate goal is to develop reliable protocols for isolating intact chromosomes and to use the C-trap optical tweezers system to measure force-extension curves. The researchers will then use CRISPR to delete specific scaffold proteins—condensins and topoisomerases—to see which ones give chromosomes their strength. If successful, this work will provide the first quantitative biophysical parameters for chromosome mechanics. That deeper understanding could eventually inform why chromosome segregation errors occur, but the research does not promise a direct application. Similar fundamental studies of cellular mechanics have, in the past, unexpectedly improved our understanding of how cancer cells become more deformable and invasive.