Thèses

Jeudi 19 Décembre 2024 à 13h00.

Aerotaxis and the collective spreading of social and asocial amoebae

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Directeur de thèse / thesis director :
Jean-Paul Rieu et Christophe Anjart

Membres du jury / jury members :
Olivier Théodoly, Rapporteur
Nicolas Desprat, Rapporteur
Carine Douarche, Examinatrice
Violaine See, Examinatrice

Abstract :
We address aerotaxis at the single cell level for two differing amoebae: the cooperative social amoeba Dictyostelium discoideum (Dd) and the solitary asocial amoeba Acanthamoeba castellanii (Ac). When confined under a glass coverslip, cell colonies establish a self-generated O2 gradient and escape the hypoxic center via aerotaxis [1]. In the case of Dd, a robust ring of cells emerges and expands at constant speed and cell density [2][3]. For Ac, at high cell densities a short-lived dissipating ring accompanied by aerotactic ballistic-like cells appear - with only the latter arising at lower initial densities. A reaction-diffusion (RD) model which accounts for the aerotaxis of Dd was recently presented [2][3]. Using homogeneous O2 environments and controllable microfluidic devices [4] we find a cell density dependence of Ac cellular motility parameters (diffusion coefficient, persistence time, and aerotactic potential). We integrated this perspective into our RD model, in agreement with experimental findings and potentially accounting for a wider range of cells.

[1] M. Deygas, R. Gadet, G. Gillet, R. Rimokh, P. Gonzalo, and I. Mikaelian, “Redox regulation of EGFR steers migration of hypoxic mammary cells towards oxygen,” Nature Communications 2018 9:1, vol. 9, no. 1, pp. 1–14, Oct. 2018, doi: 10.1038/s41467-018-06988-3.
[2] O. Cochet-Escartin et al., “Hypoxia triggers collective aerotactic migration in dictyostelium discoideum,” Elife, vol. 10, Aug. 2021, doi: 10.7554/ELIFE.64731.
[3] S. Hirose et al., “The aerotaxis of Dictyostelium discoideum is independent of mitochondria, nitric oxide and oxidative stress,” Front Cell Dev Biol, vol. 11, p. 1134011, Jun. 2023, doi: 10.3389/FCELL.2023.1134011/BIBTEX.
[4] S. Hirose, J. P. Rieu, O. Cochet-Escartin, C. Anjard, and K. Funamoto, “The Oxygen Gradient in Hypoxic Conditions Enhances and Guides Dictyostelium discoideum Migration,” Processes, vol. 10, no. 2, p. 318, Feb. 2022, doi: 10.3390/PR10020318/S1.

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