Abstract
The lecture discussed two further aspects of cell motility : the shape of moving cells and the efficiency of cell motility, again using keratocyte cells as an example.
The shape of moving cells on a solid substrate was studied both analytically and in theoretical models that have to be solved numerically. The general idea is to take into account the forces acting on the edge of the cell and to consider that dissipation is essentially due to the friction of the cytoskeleton on the solid surface. This reduces the study of motion to that of membrane deformation. The forces acting on the edge of the cell are surface tension due to the activity of the cortical layer, protrusion forces due to actin polymerization and depolymerization, and possibly stress fibers. The problem is usually solved numerically by various methods. One interesting method is the phase field method, which was developed to study crystallization kinetics. All approaches lead to "canoe" shapes similar to the experimental ones, and the comparison between theoretical and experimental shapes does not seem to discriminate between the different theoretical descriptions.
