Each genotoxicity test has a specific mechanism for detecting genetic damage.
1. Ames Test: Utilizes strains of Salmonella that carry mutations making them unable to synthesize certain amino acids. When exposed to a genotoxic substance, the bacteria regain the ability to grow without the amino acid, indicating a mutation has occurred. 2. Comet Assay: Cells are embedded in agarose gel, lysed, and subjected to electrophoresis. DNA fragments migrate out of the cell, forming a comet-like appearance under fluorescence microscopy if damage is present. 3. Micronucleus Test: Cells are treated with the test substance and then examined for the presence of micronuclei, indicative of chromosomal damage. 4. Chromosomal Aberration Test: Cells are exposed to the test substance and then arrested during mitosis. Chromosomes are stained and analyzed for structural alterations.
