Colloquium: Kirill Polovnikov, Skolkovo Institute of Science and Technology
Topology, Loops, and Life: How Chromosomes (Re)-Fold Without Tangling
Event Details:
- Date: February 26, 2026
- Time: 3:45 PM - 4:45 PM
- Location: 1080 Physics Research Building
- Faculty Host: Michael Poirier
Abstract
Every human cell must repeatedly condense nearly two meters of DNA into a ~10-micron nucleus, segregate it with exquisite accuracy during cell division, and then re-establish a dynamic three-dimensional architecture that controls gene expression. From a soft-matter physics perspective, this poses a remarkable question: How can such extraordinarily long polymers reorganize in a crowded, topologically constrained environment without catastrophic tangling?
In this colloquium, I will show how ideas from polymer physics, topology, and statistical mechanics are reshaping our understanding of chromosome organization. I will begin by explaining what “topological interactions’’ mean for long unknotted polymers and how they produce crumpled, territorially segregated states—distinct from both entangled Flory melts and Lifshitz equilibrium globules—and how these predictions align strikingly with Hi-C and super-resolution imaging data.
I will then highlight several recent advances:
- effective Hamiltonian and quenched-loop disorder models reveal chromosomes as crumpled polymers folded into random loops;
- these analytically tractable frameworks allow us to infer stoichiometry of loop-extruding cohesin motors directly from high-throughput data;
- topology-preserving molecular dynamics combined with cell-phase synchronized experiments show that mitotic chromosomes are internally knotted, implying that their reorganization requires active disentanglement.
I will conclude by outlining future directions: establishing the physical mechanisms linking loop extrusion to biological function; exploring whether topologically stabilized polymers form a distinct universality class connected to Kardar–Parisi–Zhang dynamics; and developing physics-informed generative models toward a predictive “Standard Model’’ of the 4D genome. More broadly, chromatin provides a uniquely rich platform for probing active, disordered, and kinetically trapped states, highlighting the deep role of theoretical soft-matter physics in advancing mechanistic understanding of living systems.
Bio
Kirill Polovnikov is an Assistant Professor at the Skolkovo Institute of Science and Technology and an Alexander von Humboldt Fellow at the University of Potsdam. He works at the interface of theoretical biophysics, soft matter and polymer physics, and machine learning for biological data. Kirill received his PhD in Theoretical Physics from Moscow State University in 2019 and subsequently conducted postdoctoral research at MIT and Institut Curie. His research focuses on the statistical physics and topology of chromatin, the dynamics of long polymers in crowded environments, and quantitative models of genome organization. He has led multiple externally funded research projects (exceeding $1M total support), supervises PhD and MSc trainees, and is an active contributor to the international Biophysics community through invited talks, seminar organization, and review service.