Cell Enucleation, Cybrids, Reconstituted Cells, and Nuclear Hybrids

Cell enucleation and fusion provide a technology to determine if the cell cytoplasm contains stable regulatory substances that might modulate nuclear gene expression. It has been reported that added cytoplasm can have either a permanent, long-lived (2–8 weeks), short-lived (1–2 days), or no effect on the phenotype of the nuclear recipient. The protocols described in this chapter may be useful for helping to dissect the nature of these cytoplasmic regulatory substances. In addition, by fusing a cytoplast with a karyoplast, a viable “reconstituted” cell can be produced. Alternatively, by fusing a cytoplast from one cell to another whole cell, a cytoplasmic hybrid or cybrid is formed. Finally, by fusing a karyoplast to another whole ceil it is possible to form a nuclear hybrid. The various protocols for the production and isolation of these cellular constructs are described in this chapter.