No abstract

A simple and reproducible procedure for the introduction of DNA into mammalian cells by electroporation is described. The parameters involving the cells, the DNA, and the electric field are investigated. The procedure has been applied to a broad range of animal cells. It is capable of transforming more than 1% of the viable cells to the stable expression of a selectable marker.

Oxidized guanine (8-oxo-7,8-dihydroguanine; 8-oxo-G) is a potent mutagen because of its ambiguous pairing with cytosine and adenine. The Escherichia coli MutT protein specifically hydrolyzes both 8-oxo-deoxyguanosine triphosphate (8-oxo-dGTP) and 8-oxo-guanosine triphosphate (8-oxo-rGTP), which are otherwise incorporated in DNA and RNA opposite template A. In vivo, this cleaning of the nucleotide pools decreases both DNA replication and transcription errors. The effect of mutT mutation on transcription fidelity was shown to depend on oxidative metabolism. Such control of transcriptional fidelity by the ubiquitous MutT function has implications for evolution of RNA-based life, phenotypic expression, adaptive mutagenesis, and functional maintenance of nondividing cells.