Detection of DNA strand breaks in single cells using flow cytometry.

A preliminary method is reported of alkaline unwinding of DNA within single cells and quantitation of the single-stranded and double-stranded DNA with the fluorescent probe acridine orange. A suspension of alkali-treated cells is obtained and analysed by flow cytometry. An increase in the amount of single-stranded DNA is taken as an indication of strand breaks. An advantage of this method is that a large number of cells can be individually analysed for DNA strand breaks. A measurement of DNA content is also obtained, making it possible to discriminate between cells in various parts of the cell cycle.