Research For Biophysical Mechanism Of Cell Motility And Division Via Phase Field Dynamics Model

Being widespread in nature, in our daily life and industry, the soft matter playsan important role in our lives. This paper mainly discussed the mechanism aboutbacterial cell division and cell motion via the field phase method.Prokaryotic cell division mechanism is a hotspot issue in recent years. As thecomponent of Z ring, FtsZ protein plays an important role in cell division. In thesecond chapter, we coupled the field phase method with the Z-ring force generatingmechanism, and focused the effect of the initial state and the reaction rate. Byanalyzing the magnitude of the Z-ring force, the contract rate of Z-ring, the fraction ofthe subunits in the ring that are GDP bound, and the length distribution of filaments inthe ring, we tried to resolve the question of how Z-ring could generate a constrictionforce. We also found that the result of the numerical solution come to terms with theanalytical solution well.Cell motion is a complex biological process that involves the cooperativeinteractions between the cytoskeleton and cell membrane, and these interactionsgenerally include these interactive energies generated from the surface tension and thebending elastic energy of the cell membrane, the “protrusive” and “contractile” forcesseparately driven by actin polymerization into cytoskeletons and myosin contraction,and the adhesion between the cell and the substrate. Herein, one computational modelbased on the phase field method and the reaction-diffusion model is subsequentlydeveloped to describe this complicated biological process, coupling the cellmovement and cell morphologenis with the dynamic behaviors of actin assemble intoactin filaments, the physiological functions of myosin, and the interaction between thecell and the substrate. In the computational model for cell motion, the movingboundary with physical membrane properties is proposed to numerically solve theproblem involved in the computational efficiency. The fish keratocytes, fast movingcells that maintain their morphology, are applied in the present study, and the relatedsystem parameters are chosen. The steady state and movement velocity of cells areobtained with a wide range of aspect ratios and movement velocities in thecomputational model, which are found to be well in agreement with the associatedexperimental results in vitro. In addition, the dependences of the movement velocityand the steady state of the cells are in detail studied on system parameters that are theconcentrations of the actin and myosin, as well as the actin rate constants. It will be straightforward to extend this method to more complicated systems,such as cell contraction, and cell movement in actin flow and shear flow.