title: Assessment of the relative toxicity of Cu2+ by measuring structural changes of supercoiled DNA.
abstract: A method for the measurement of the relative toxicity of Cu2+ in aquatic environments is proposed. It is based on the quantitative measurement on the shape change of the supercoiled DNA after it is contacted with different levels of Cu2+ for various time intervals. In the absence of any redox reagents, all supercoiled DNA degraded into other forms of DNA after 24h incubation in the presence of 5.13 x 10(-3), 5.08 x 10(-4) and 5.35 x 10(-5)mol/L Cu2+. At a lower Cu2+ concentration (10(-6)mol/L), 44% of supercoiled DNA retained its original supercoiled form after 24 h, and 29% after 48 h. The concentration of RC50, i.e. concentration of pollutants at which 50% of the supercoiled DNA was relaxed compared to control samples, can be obtained from the does-response curves at different exposure time, which may provide a rapid and convenient approach to assess the relative toxicity of environmental pollutants.
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China. gpan@rcees.ac.cn
authors.forename: Gang
authors.initials: G
authors.lastname: Pan
authors.forename: Guohua
authors.initials: G
authors.lastname: Chang
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Giusti
mesh_terms: D003300:Copper / Q000032:analysis / Q000633:toxicity*; D004269:DNA, Bacterial / Q000737:chemistry; D004278:DNA, Superhelical / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000494:pharmacology; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D014874:Water Pollutants, Chemical; D003300:Copper; D006851:Hydrochloric Acid