Rearrangement of the cytoskeleton and nuclear transfer in Tetrahymena thermophila cells fused by electric field.

This paper reports on electrofusion of Tetrahymena thermophila and on the reorganization of the cytoskeleton in fused cells. Important factors influencing the fusion yield are the number of electric pulses, the strength of alternate current field and cell density. The process of cell fusion consists of a mutual intermingling of cell membranes following their deformation at the contact zone, followed by the formation of cytoplasmic bridges and simultaneous disruption of portions of the submembranous cytoskeleton (epiplasm) and alveolar sacs. The course of further changes in cell organization depends on the polarity of fused cells. Homopolar fusion partners integrate by gradual translocation of portions of cortical cytoskeletal elements. In contrast, cortical integration of heteropolar fused cells is limited. Cytoskeletal integration is particularly promoted if the cells are incubated in non-growing conditions. Cortical integration leads to a high frequency of micronuclear transfer when a micronucleate strain is used as a donor and an amicronucleate strain is used as a recipient in the fusion experiments.