2024/11/20 by Yasutaka Kakui, Yoshiharu Kusano, Tereza Clarence +4 · 1 voice
Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · #Genomics and Chromatin Dynamics #Chromosomal and Genetic Variations #Microtubule and mitosis dynamics
paper · pdf · doi:10.1101/2024.11.19.623756
openalex publication_date 2024/11/20 · openalex created_date 2024/11/21 · openalex updated_date 2026/07/28
Mitotic chromosomes give genome portions the required compaction and mechanical stability for faithful inheritance during cell divisions. Here, we record human chromosome dimensions from their appearance in prophase over successive times in a mitotic arrest. Chromosomes first appear long and uniformly thin. Then, individual chromosome arms become discernible, which continuously shorten and thicken - the longer a chromosome arm, the thicker it becomes. The observed chromosome arm length to width relationship can be described by a power law with progressively increasing exponent. In the search for a molecular explanation of this behavior, the popular loop extrusion model provides no obvious means by which longer arms become thicker. Instead, we find that simulations of an alternative loop capture model recapitulate key features of our observations, including the gradually developing arm length to width relationship. Our analyses portray chromosomes as out-of-equilibrium structures in the process of transitioning towards, but on biologically relevant time scales not typically reaching, steady state.