Increased cotransformation of distant markers and altered patterns of DNA-cell interactions following the exposure of transforming DNA to two carcinogenic and mutagenic alkylating agents, diethyl and dimethyl sulfate.

Transforming DNA exposed to either diethyl sulfate (diES) or dimethyl sulfate (diMS) is inactivated. The rate of inactivation depends on the marker tested and on the chemical used: diMS is more active than diES. Cotransformation of linked markers is similarly depressed. In contrast, there is a transient increase in the cotransformation of distant, unlinked markers. These observations indicate that some of the intermolecular complexes of transforming DNA created in the test tube by the treatment with diES and diMS are biologically active. Radioactively labeled DNA treated with diES or diMS changes its patterns of interaction with cellular surfaces that are characteristic of untreated DNA. A possibility is considered that such alterations in DNA-protein interactions as well as the ability of these alkylating agents to transpose fragments of chromosomal material may play an important role in the processes of mutagenesis and, especially, carcinogenesis.