Flow cytometry assay for rapid analysis of DNA strand breaks

A method is described of analyzing breaks within nuclear DNA using flow cytometry of extracted nucleoids. Breaks in the DNA molecule are detected by the relaxation of supercoiled topological domains and may be observed at a frequency of 1:5 × 10 5 bp or better. This represents an improvement over previous methods of such analyses in that both the speed of data accumulation is increased due to the elimination of potentially confounding factors of extended lysis incubation and the use of DNA intercalators. Such a technique may find application in studies which require very rapid assessment of rare breaks within the linear DNA molecule, data may be recorded with minimal cell processing approximately 60–90 seconds after lysis of live cellular material.