mutagen

Mutagen refers to an agent or process that increases the rate of genetic mutations in DNA. Mutagens can modify DNA directly or indirectly through chemical reactions, radiation, or biological activity. While many mutagens are also capable of causing cancer, mutagenicity and carcinogenicity are related but distinct concepts.

Mutagens are commonly classified as chemical, physical, or biological. Chemical mutagens include base analogues that mispair during replication, alkylating agents that modify bases, and intercalating compounds that distort the DNA helix. Physical mutagens include ultraviolet and ionizing radiation, which can produce DNA lesions such as thymine dimers or double-strand breaks. Biological mutagens encompass transposable elements that insert into new genomic locations and viruses that integrate into host DNA.

Mutagens produce a range of genetic changes, including base substitutions, insertions, deletions, frameshifts, and chromosomal rearrangements. The observed mutagenic effect depends on DNA repair capacity, replication fidelity, and cellular context, so different organisms and tissues can respond differently to the same agent.

Mutagenicity is assessed using specialized tests. The Ames test, which uses bacteria to detect mutagenic potential, is a widely used screening tool. Additional assays, such as micronucleus tests, comet assays, and sequencing-based approaches, help quantify mutation frequency and spectrum. Results inform chemical safety evaluations and regulatory decisions.

Applications of controlled mutagenesis include functional genomics, creation of model organisms, and strains for biotechnology. Safety and regulatory frameworks require assessment of mutagenic potential for chemicals and environmental exposures, with classifications guiding labeling and exposure limits.