Anders has been at Washington University since 1983, and is Professor of Physics. His research interests are focused on modeling the polymerization processes underlying the crawling motions of cells. This work is being performed in collaboration with Professors John Cooper at the Washington University School of Medicine and David Sept in the Washington University Department of Biomedical Engineering. The motions of cells, extensions of their boundaries, and cell division often involve polymerization and depolymerization of the protein actin. This protein forms long, fairly stiff filaments, whose growth can supply the mechanical force necessary for cell motion or shape changes. The filaments are often found in branched or cross-linked networks. The distribution of actin inside cells displays spontaneous dynamic behavior which is similar to that of an excitable medium. The modeling work treats these phenomena with methods including Brownian-dynamics and stochastic-growth simulations, and analytic theory. The main goals of the modeling are to are to understand how the structures formed by actin filaments respond to external stimuli, to establish how the structure of the networks is determined by the activities of cross-linking proteins, to pin down the main energetic factors underyling actin bundling, and to establish how the cell cytoplasm functions as an excitable medium.
Shown above is the structure of an "actin tail" obtained by computer simulation. Take a look at a movie of two actin filaments trying to bundle or one of the growth of an actin filament attached to an obstacle. These movies are obtained from Brownian dynamics simulations by Le Yang and Jie Zhu, and the work is supported by the National Science Foundation under Grant DMS-0240770.
Effects of Hydrolysis on Force Generation by Actin Filaments
Actin Polymerization Overshoots and Hydrolysis as Assayed by Pyrene Fluorescence