title: The comet assay: topical issues.
abstract: The comet assay is a versatile and sensitive method for measuring single- and double-strand breaks in DNA. The mechanism of formation of comets (under neutral or alkaline conditions) is best understood by analogy with nucleoids, in which relaxation of DNA supercoiling in a structural loop of DNA by a single DNA break releases that loop to extend into a halo-or, in the case of the comet assay, to be pulled towards the anode under the electrophoretic field. A consideration of the simple physics underlying electrophoresis leads to a better understanding of the assay. The sensitivity of the assay is only fully appreciated when it is calibrated: between one hundred and several thousand breaks per cell can be determined. By including lesion-specific enzymes in the assay, its range and sensitivity are greatly increased, but it is important to bear in mind that their specificity is not absolute. Different approaches to quantitation of the comet assay are discussed. Arguments are presented against trying to apply the comet assay to the study of apoptosis. Finally, some of the advantages and disadvantages of using the comet assay on lymphocyte samples collected in human studies are rehearsed.
authors.affiliation: Department of Nutrition, Faculty of Medicine, University of Oslo, Oslo, Norway. a.r.collins@medisin.uio.no
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Collins
authors.forename: Amaia Azqueta
authors.initials: AA
authors.lastname: Oscoz
authors.forename: Gunnar
authors.initials: G
authors.lastname: Brunborg
authors.forename: Isabel
authors.initials: I
authors.lastname: Gaivão
authors.forename: Lisa
authors.initials: L
authors.lastname: Giovannelli
authors.forename: Marcin
authors.initials: M
authors.lastname: Kruszewski
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Smith
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stetina
mesh_terms: D002138:Calibration; D002470:Cell Survival; D020552:Comet Assay / Q000379:methods* / Q000592:standards*; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D004272:DNA, Mitochondrial / Q000032:analysis; D006801:Humans; D008214:Lymphocytes / Q000737:chemistry; D012680:Sensitivity and Specificity
chemical_list: D004272:DNA, Mitochondrial