A stochastic modeling for the emergence of loners in social amoebae

Social Amoebae cells use the Quorum Sensing mechanism to activate a multicellular aggregation process under environmental stress conditions. Quorum Sensing is based on the production and diffusion in the environment of signal molecules whose concentration is sensed by the cells themselves. In this way a group of cells can switch on a novel collective behavior in a coordinate manner, when the concentration of signal molecules exceeds a threshold value. For social Amoebae, however, it was recently shown [1] that some cells (loners) do not join the multicellular aggregate. In the same paper it was also shown how loner density depends on the initial cell density and on the diffusion coefficient, by means of both experiments and simple theoretical models, based on the stochasticity of the activation process at the single cell level. The aim of this thesis project is to improve the theoretical model introduced in [1] and to reproduce the changes of the fluctuations in loner density observed experimentally. [1] Eco-evolutionary significance of loners; F.W. Rossine et al., PLoS Biology 18(3): e3000642