A genotoxicological technique for measuring DNA damage in an individual cell using single-cell gel electrophoresis. Cell DNA fragments assume a "comet with tail" formation on electrophoresis and are detected with an image analysis system. Alkaline assay conditions facilitate sensitive detection of single-strand damage.

(single cell gel electrophoresis) A rapid, simple, visual and sensitive technique for measuring DNA breakage in individual mammalian cells in response to a test agent. A cell is immobilized in agarose and made permeable and the broken DNA migrates out under the influence of the electric field. A damaged cell has the appearance of a comet with a brightly fluorescent cell body and a tail whose length and fluorescence intensity are related to the number of DNA-strand breaks induced by the test agent.