Orateur
Description
When reaching high densities, Dictyostelium discoideum (Dd) cells find themselves lacking oxygen and spontaneously self-organize into dynamic, size-stable aggregates. The aggregates coexist with a dispersed cellular phase resulting in an original example of micro phase separation of living cells (Carrere et al, Nat Comm, 2023). This form of collective behavior is distinct from the classical cAMP-mediated aggregation associated with starvation. We have previously shown that the aggregates’ typical size emerges from a balance between two competing interactions: a short-range adhesive attraction, and an effective long-range repulsion driven by self-generated oxygen gradients and the aerotactic ability of the involved cells. As such, this phase separation is primarily driven by oxygen availability with no signature of two different cell populations. However, unlike in other instances of micro phase separation in inert systems, the cellular aggregates are highly motile, display persistent trajectories and dynamic interactions over several days. Using mean-squared-displacement analysis, we quantify their dynamics and uncover a clear size dependence: larger aggregates move more persistently and explore broader regions than smaller ones. This behavior suggests a high degree of collective coordination within aggregates. Preliminary simulations based on the Cellular Potts Model support this cooperative scenario and reproduce qualitative features of the experimental observations. To decipher the mechanisms of this cooperation, we use fluorescence imaging to track individual cells and quantify the exchange fluxes of cells between both phases. We expect to uncover from these experiments how cells behave inside an aggregate, and obtain a clearer picture of the mechanical motion of the whole aggregate as a collective. All these observations underline the potential of this unique phenomenon, which may constitute a new model system for active matter.
| Do you submit an abstract for a talk or a poster? | talk |
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| If your abstract isn’t selected for a plenary talk, would you like to present it as a poster? | Yes |