What is a Comet Assay ?

The comet assay, also called the 'Single Cell Gel Assay', is the technique to detect  DNA damage and repair at the level of single cells. This is one of the advanced technique in the oncology. This technique was developed by Swedish researchers  Östling & Johansson in 1984. This technique was later modified by N.P. Singh et al., in 1988 as Alkaline Comet Assay.
'Comet Assay' is one of the most popular  tests of DNA damage detection  (e.g., single- and double-strand breaks, oxidative-induced base damage, and DNA-DNA/DNA-protein cross linking ) by electrophoresis, developed in recent years.

Advantages Of Comet Assay :

  • Very high sensitivity to detect DNA damage
  • Rapid and easy to handle
  • Little amount of cell samples needed
  • Applied to most eukaryotic cells


Comet Assay involves the following steps :

  1. Slide preparation : Mixing of cells with low melting agarose, and spread over glass microscope slides

  2. Lysis: lysis of cell membrane and other proteins

  3. Unwinding of DNA

  4. Electrophoresis

  5. Neutralization

  6. Staining and scoring

Applications :

  • Genotoxicity Studies
  • DNA Repair
  • Apoptosis
  • Visual quantification of DNA double strand breaks in bacteria
  • Free Radical Biology
  • Nutritional Toxicology
  • Biomonitoring
  • Clinical Applications
  • Cell cycle analysis

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