Doktorski seminar - Blaž Ivšić

O B A V I J E S T

BLAŽ IVŠIĆ

održat će znanstveni kolokvij (doktorski seminar) iz Biofzike pod naslovom

Sprega dinamike proteina Rac1 i oblika stanica Dictyostelium discoideum

Eukaryotic cells crawl by coupling intracellular signalling to membrane mechanics and cytoplasmic flow. We examine how that coupling organises motility patterns using a minimal mechanochemical model. The key ingredient is a spatially variable surface tension along the cortex, linked to activator concentration and acting alongside a normal protrusive stress. In a diffuse-interface level-set framework coupled to Stokes flow and a reaction--diffusion--advection (RDA) system, these couplings generate Marangoni surface flows and cytosolic advection that reshape canonical RDA patterns.

To validate the model, we imaged in vitro Dictyostelium discoideum expressing a Rac1-GTP probe and defined a motility-centric taxonomy: stationary, alternating runners, circular runners, run-and-stop, and run-and-turn. By tuning protrusive and surface-tension couplings, the model reproduces three of the four motile classes and maps how coupling ratios select characteristic shapes (fan, stadium, egg, flat-front, dumbbell). The results reveal regimes in which behaviour is dominated, respectively, by reaction--diffusion, by flow-modified patterns (persistent runs), or by geometry-mediated feedback (turning).

This work provides a transparent baseline for future extensions, including spatially varying rheology, alternative surface-tension laws, and additional signalling species, and is readily adaptable to other eukaryotic cell types.

Keywords: cell motility, reaction–diffusion–advection system, cytosolic and cortical flows, variable surface tension.

Seminar će se održati u petak 3. listopada 2025. godine u 11:00 sati u predavaonici F-201 Fizičkog odsjeka Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu.

Pozivaju se studenti doktorskog studija Fizike, smjer Biofizika, da prisustvuju seminaru, ako nisu spriječeni.

Voditelj smjera:

Izv. prof. dr. sc. Matko Glunčić, v. r.