The comet assay is a sensitive, inexpensive, fast, and easy-to-use method widely used in genotoxicity testing and biomonitoring studies. It can be applied using a few cells and on almost every cell type to assess a range of different DNA lesions, DNA repair activity and even DNA methylation levels, at the individual cell level. The principle is simple, during electrophoresis relaxed DNA strands move toward the anode away from the nucleoid core, appearing like a “comet”, hence the name of the assay. Incubation with lesion specific enzymes allows the detection of specific types of DNA lesions such as DNA oxidative damage, repair efficiency and methylation. The distribution of DNA within the comet relates to the extent of DNA damage present in the cell. © 2024 Elsevier Inc. All rights reserved.

Armanda Teixeira-Gomes and Joana Pires are supported by Fundação para a Ciência e Tecnologia (FCT-MCTES), and by the European Social Fund, through Programa Operacional Capital Humano (POCH), under the individual grant SFRH/BD/121802/2016 and project grant PCIF/SSO/0017/2018.