Uptake of isolated metaphase chromosomes by mammalian cells in vitro

Abstract

In an autoradiographic investigation, it was found that isolated 3H-thymidine-labelled metaphase chromosomes can penetrate into mammalian cells in vitro. The progressive changes in the cellular labelling patterns with time indicate that, in most cases, the ingested chromosome is degraded in the cytoplasm of the recipient cell and the chromosomal DNA is integrated into the host nuclear DNA. This integration of extracellular chromosomal DNA into the recipient cell DNA may involve DNA macromolecules rather than free nucleotides, and in most cases, the chromosomal DNA becomes randomly integrated among the chromosomes of the recipient cell. Rarely, whole extracellular chromosomes may become incorporated into a cell without being degraded, although this has not been established with certainty.