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【Abstract】

Excitable and oscillatory dynamics are a prime example of spatio-temporal structures in systems far from equilibrium. In living cells, this class of nonlinear dynamics are often found to be tied to membrane and cytoskeletal regulation. In eukaryotes, when and where actin protein polymerize at the cortical layer of cell membrane dictates a large part of cell deformation observed during extracellular fluid and particle intake as well as cell migration. In amoeba Dictyostelium, periodic traveling waves and patches of F-actin are thought to serve as a prepattern for a cup-shaped membrane deformation for fluid intake. By analyzing wave nucleation spatial phase singularities, we have shown earlier that the wave patterns can be understood from excitable dynamics driven by positive feedback between lipid signaling and F-actin formation (Taniguchi et al, PNAS 110, 5016-, 2013). Recently, by assuming reaction-diffusion with mass conservation and a certain force distribution, we showed that the prepattern (the signaling patches) can give rise to a self-enclosing cup structure (Saito and Sawai, iScience, 103087, 2021). In addition, by analyzing wave nucleation and propagation in cells on structured surfaces, we found micrometer-scale topographical /curvature dependency of the wave that supports guidance of polarized cells along micrometer-scale ridges (Honda et al, PNAS, 118, e211028118, 2021). If time permits, I will also touch upon our recent attempts to integrate data-driven and hypothesis driven approach with machine learning morphometry and reaction-diffusion membrane deformation dynamics (Imoto et al, PLoS Compt Biol 17, e1009237, 2021).