title: Expression of prokaryotic genes after transfection of X-irradiated plasmids into primate cells.
abstract: Expression of the prokaryotic gene for chloramphenicol acetyltransferase (EC 2.3.1.28) (CAT) in primate cells transfected with X-irradiated plasmid pSV2CAT was determined in transient expression assays. CAT expression did not depend upon the presence of supercoiled plasmids, but relaxed circular forms were essential. X-ray conversion of relaxed circles to linear forms paralleled the loss of CAT expression, with identical D0's in the first part of dose-response curves. X-ray-induced loss of supercoiled forms was complete at much lower doses. The D0 for inactivation of CAT expression by X irradiation of the plasmids in 1 mM Tris buffer was 270 Gy; it was 13 Gy for plasmids irradiated in water. The D0's for conversion of pSV2CAT to relaxed circle forms were only one-seventh as large as the D0's for CAT inactivation after X-ray in water or in 1 mM Tris buffer. Expression of the CAT gene in some representative repair-deficient human fibroblasts transfected with X-irradiated pSV2CAT was less than in monkey CV-1 cells or cell lines from normal human subjects. These results demonstrate a novel means to study low levels of X-ray damage in DNA correlating specific X-ray damage in the DNA with expression of the gene in unirradiated primate cells.
authors.forename: L
authors.initials: L
authors.lastname: Piazza
authors.forename: J
authors.initials: J
authors.lastname: Masch
authors.forename: J
authors.initials: J
authors.lastname: Feingold
authors.forename: F
authors.initials: F
authors.lastname: Mendez
authors.forename: J
authors.initials: J
authors.lastname: Maio
authors.forename: R
authors.initials: R
authors.lastname: Bases
mesh_terms: D000123:Acetyltransferases / Q000096:biosynthesis / Q000235:genetics*; D000818:Animals; D001260:Ataxia Telangiectasia / Q000235:genetics; D015500:Chloramphenicol O-Acetyltransferase; D004249:DNA Damage; D004262:DNA Restriction Enzymes; D015245:Deoxyribonuclease BamHI; D005347:Fibroblasts / Q000201:enzymology; D000882:Haplorhini; D006801:Humans; D010957:Plasmids / Q000528:radiation effects*; D014170:Transformation, Genetic; D014965:X-Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D000123:Acetyltransferases; D015500:Chloramphenicol O-Acetyltransferase; D004262:DNA Restriction Enzymes; D015245:Deoxyribonuclease BamHI; D001616:beta-Galactosidase