Shape Behavior of Closed Layered Membranes and Cytokinesis

Abstract

The analysis of the mechanism of cell cleavage in general consists in studies of cellular molecular processes which generate forces acting on the cell surface, and in studies of the effect of these forces on cell shape. Knowledge about both these aspects of cytokinesis is rapidly increasing (White & Borisy 1983, Rappaport 1986, Satterwhite & Pollard 1992, Fishkind & Wang 1995). The focus in this contribution is on the mechanical aspects of the movement of the cell’s plasma membrane in relation to the shape behavior of closed layered membranes. First we shall review some general properties of shapes of vesicular structures for the case of a laterally homogeneous membrane. Then we shall specify what modifications of the treatment are needed for describing cytokinesis. Some examples of relevant shape transformations will be presented, e.g., it will be shown how cell shapes depend on the forces constricting the equatorial region of an axially symmetrical cell. Finally, a mechanism will be described for the emergence of a laterally inhomogeneous distribution of membrane-embedded and membrane-associated cell components, based on an assertion that such a distribution is caused by variations of membrane principal curvatures over the cell surface.