DNA damage-inducible gene expression and formation of 5-fluorouracil-resistant mutants in Escherichia coli exposed to 2-dodecylcyclobutanone

摘要

2-Dodecylcyclobutanone (2-DCB) is formed by the radiolysis of palmitic acid and is present at low part-per-million (approximately 0.1 μ g/g) levels in irradiated meat products. Recently, equivocal results obtained using a DNA strand breakage test, the Comet Assay, raised the possibility that 2-DCB could be a weak genotoxin. To more accurately assess 2-DCB's potential genotoxicity, it was tested for the ability to increase expression of the DNA damage-inducible genes dinD, nfo, recA, and umuDC using Escherichia coli that contained promoter/β-galactosidase reporter constructs, and for the ability to increase the formation of 5-fluorouracil (5-FU)-resistant mutants. When E. coli was exposed to 125, 250, 500, and 1000 μ g/mL 2-DCB, with and without exogenous metabolic activation, no increase in dinD, nfo, recA, or umuDC gene expression, as measured by an increase in P-galactosidase activity, was observed. In addition, 2-DCB did not increase the formation of 5-FU-resistant mutants in E. coli, with and without exogenous metabolic activation, at the same concentrations. No evidence of 2-DCB-associated genotoxic activity was detected in this study.