OECD 489: Alkaline comet assay (in vivo mammalian)

The In vivo Alkaline Comet (single cell gel electrophoresis) Assay is used to identify chemicals that cause DNA damage by detecting DNA strand breaks in cells or nuclei isolated from multiple tissues of animals, usually rodents, that have been exposed to potentially genotoxic material. 

The nuclear DNA undergoes electrophoresis under alkaline conditions (>pH 13) and results in structures resembling comets which can be observed by fluorescent microscopy. The amount of DNA breakage is based on migration of the DNA fragments. 

The assay can detect single and double stranded breaks which may be repaired, resulting in no persistent effect, may be lethal to the cell, or may be fixed into a mutation resulting in a permanent viable change. They may also lead to chromosomal damage which is also associated with many human diseases including cancer.