Foreign DNA in Mammalian Cells and Organisms

Abstract

Mammalian cells have the capacity for taking up foreign DNA and to integrate this DNA into their own genomes under appropriate conditions. This integration may not be stable in all cells upon their continued replication. The functional consequences of foreign DNA integration depend on a number of factors, like chromosomal site of integration, extent of organizational alterations in the recipient genome at locations close to and remote from the insertion site, on the de novo methylation and transcriptional inactivation of the inserted foreign genes, and on factors not yet understood at the present time. The acquisition of foreign DNA can be advantageous or deleterious for the recipient cell. It may lead to insertional mutagenesis, cell transformation, cell death, or may bestow upon the cell new functional facilities. Since we have shown that foreign DNA ingested with the daily food supply survives in part the digestive regimen in the gastrointestinal tract of mice, reaches the bloodstream of these animals and can be traced to the nuclei of intestinal epithelia, peripheral leukocytes, spleen and liver cells, it will be important to study the fate of foreign DNA also in mammalian organisms. The long-term sequelae of this life-long influx of foreign DNA into lite mammalian organism are not known.