Analysis, Dynamics, and Applications seminar: Mete Demircigil

University of Arizona

When

12:30 – 1:30 p.m., Oct. 22, 2024

Collective Cell Movement under Self-Generated Aerotactic Gradients.

Using a self-generated hypoxic assay, it is shown that Dictyostelium discoideum displays a remarkable collective aerotactic behavior: when a cell colony is covered, cells quickly consume the available oxygen and form a dense ring moving outwards at constant speed and density.

We propose a simple, yet original PDE model, that enables an analytical qualitative and quantitative study of the phenomenon and reveals that the collective migration gives rise to traveling wave solutions, whose propagation can be explained through the interplay between cell division and the modulation of aerotaxis. Moreover, the model gives rise to a dichotomy on pulled and pushed waves depending on the strength of aerotaxis.

For the sake of giving a better description of the long-term asymptotics, we propose an analogous PDE model using a similar modeling hypothesis and precise asymptotics on the spread of level sets are given.

The latter model may also be seen as the large-population limit of a stochastic finite-population model. We show convergence of this stochastic model to the given PDE in the large-population limit. The stochastic model is then studied through the lens of ancestral lineages, a recently proposed framework. This methodology gives a dual viewpoint on the pulled/pushed dichotomy.

Finally, a similar experiment in Acanthamoeba is investigated: by proposing a mesoscopic model accounting for collisions, we are able to infer a new density-dependent model, which shines light on characterizing differences between the two experiments. The modeling inferences are confirmed by an experimental investigation of the cell behavior.