IPLS/BioP Seminar: Dr. Matthias Merkel (Aix-Marseille University)

Abstract: Understanding how mechanical properties of biological tissues arise from collective cellular behavior is vital for understanding the mechanisms that guide embryonic development, cancer growth, and wound healing. I will discuss two questions.
(1) Recently, a new type of solid-fluid transition was discovered in a family of cell-based models for 2D and 3D tissues called vertex models, but the precise physical mechanism generating this transition had remained elusive. Here I discuss this mechanism and show that it is an instance of a much more general class of transitions, also relevant for the mechanics of biopolymer networks such as collagen. We show that close to the transition the elastic behavior in all these models is described by the same generic physics. We obtain analytic expressions for the elastic material properties and make parameter-free predictions.
(2) Oriented tissue deformation is a key process during animal development. From a physical perspective, deforming tissues have successfully been described as oriented active materials, but such materials are known to exhibit inherent instabilities. How are these instabilities prevented during animal development? In particular, can the presence of a chemical signaling gradient help stabilize oriented tissue deformation? We find that stability depends on whether the signaling gradient acts to extend or contract the tissue along the gradient direction. Intriguingly, developing tissues seem to exclusively use the stable extensile and not the potentially unstable contractile coupling. Our work thus points to a potential new developmental principle that is directly rooted in active matter physics.

Host: Yanlan Mao

The seminar will be hybrid- both in the LMCB Seminar Room and online. Please contact Jas Gill-Thind (j.gill-thind@ucl.ac.uk) if you do not already have the details to join the Zoom meeting.

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