Enucleation of Cultured Human Cells

Human cells were found to have a biphasic response to high g force enucleation in the presence of cytochalasin B (CB). At higher g forces, enucleation is exquisitely CB dependent. At lower g forces, enucleation becomes independent of the concentration of CB and highly dependent upon temperature. Because of the ability to manipulate this part of the response with temperature, glutaraldehyde and amphoterocin B, it is suggested that at lower g forces the rigidity of the cell membrane becomes limiting for enucleation. Cells that are sensitive to enucleation at 1g would thus be sensitive because of a difference in the physical characteristics of their membranes, rather than a different sensitivity of their receptors to CB itself. The processes involved in enucleation were found to exhibit multi-hit kinetics, and were not specific for the nucleus. A model based on the ability of CB to disrupt a subplas-malemmal network of microfilaments is presented to explain these observations.