Theoretical analysis of shape transformation of V-79 cells after treatmentwith cytochalasin B

We observed that after treatment of V-79 fibroblasts with cytochalasin B th e area of cell contact with the substrate is essentially reduced, the micro tubules are organized into rodlike structures and the actin filaments are d isintegrated. Remnants of the actin cortex become concentrated in the form of discrete patches under the plasma membrane. The described changes in the organization of the cytoskeleton and of the cortical shell are accompanied by the formation of a cell shape resembling the Greek letter phi. We calcu lated that the phi shape corresponds to the minimum of the stretching energ y of the cortical shell at relevant geometrical constraints. III line with this result, if cytochalasin B treatment was followed by colchicine applica tion which disrupted the microtubular rod, the characteristic phi shape com pletely disappeared. This study suggests that the effect of the microtubula r rod on the cell shape can be theoretically well described by taking into account some basic conditions For the mechanical equlibrium of the cell cor tical shell and the appropriate geometrical constraints. (C) 2001 Elsevier Science Ltd. All rights reserved.