title: Single-strand breakage in DNA of Escherichia coli exposed to Cd2+.
abstract: When a growing culture of Escherichia coli was exposed to 3 X 10(-6) M Cd2+, 85 to 95% of the cells lost their ability to form colonies on agar plates. Loss of viability was accompanied by considerable single-strand breakage in the DNA, with no detectable increase in double-strand breaks. A direct correlation appeared to exist between the number of single-strand breaks and the concentrations of Cd2+ to which the cells were exposed. Exposure of DNA in vitro to a Cd2+ concentration of 3 X 10(-6) M or higher, followed by sedimentation in alkaline sucrose gradients, demonstrated no single-strand breaks. Cadmium-exposed cells recovered viability when incubated in Cd2+-free liquid medium containing 10 mM hydroxyurea. During the early period of recovery, there was a lag in the incorporation of labeled thymidine, but cellular DNA, at least in part, appeared to be repaired.
mesh_terms: D002104:Cadmium / Q000494:pharmacology*; D002499:Centrifugation, Density Gradient; D004260:DNA Repair; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000187:drug effects*
chemical_list: D004269:DNA, Bacterial; D002104:Cadmium