Micronucleus Tests: Induction and quantitative measurement of chromosomal damage leading to the formation of micronuclei (MICRONUCLEI, CHROMOSOME-DEFECTIVE) in cells which have been exposed to genotoxic agents or IONIZING RADIATION.Micronuclei, Chromosome-Defective: Defective nuclei produced during the TELOPHASE of MITOSIS or MEIOSIS by lagging CHROMOSOMES or chromosome fragments derived from spontaneous or experimentally induced chromosomal structural changes.Mutagenicity Tests: Tests of chemical substances and physical agents for mutagenic potential. They include microbial, insect, mammalian cell, and whole animal tests.Mutagens: Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.Comet Assay: A genotoxicological technique for measuring DNA damage in an individual cell using single-cell gel electrophoresis. Cell DNA fragments assume a "comet with tail" formation on electrophoresis and are detected with an image analysis system. Alkaline assay conditions facilitate sensitive detection of single-strand damage.Antimutagenic Agents: Agents that reduce the frequency or rate of spontaneous or induced mutations independently of the mechanism involved.Aneugens: Agents which affect CELL DIVISION and the MITOTIC SPINDLE APPARATUS resulting in the loss or gain of whole CHROMOSOMES, thereby inducing an ANEUPLOIDY.Melastomataceae: A plant family of the order Myrtales, subclass Rosidae, class Magnoliopsida composed of tropical plants with parallel-nerved leaves.Bixaceae: A plant family of the order Violales, subclass Dilleniidae, class Magnoliopsida. Bixa contains bixin. Cochlospermum contains arjunolic acid and gum kondagogu (POLYSACCHARIDES).DNA Damage: Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.Annonaceae: The custard-apple plant family of the order Magnoliales, subclass Magnoliidae, class Magnoliopsida. Some members provide large pulpy fruits and commercial timber. Leaves and wood are often fragrant. Leaves are simple, with smooth margins, and alternately arranged in two rows along the stems.Micronucleus, Germline: The smaller, reproductive, transcriptionally inert nucleus in the cells of ciliate protozoans, as distinguished from the larger, vegetative, transcriptionally active MACRONUCLEUS. Micronuclei participate in MEIOSIS and autogamy during GENETIC CONJUGATION.Lymphocytes: White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Chromosome Aberrations: Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.Mitomycin: An antineoplastic antibiotic produced by Streptomyces caespitosus. It is one of the bi- or tri-functional ALKYLATING AGENTS causing cross-linking of DNA and inhibition of DNA synthesis.Carcinogenicity Tests: Tests to experimentally measure the tumor-producing/cancer cell-producing potency of an agent by administering the agent (e.g., benzanthracenes) and observing the quantity of tumors or the cell transformation developed over a given period of time. The carcinogenicity value is usually measured as milligrams of agent administered per tumor developed. Though this test differs from the DNA-repair and bacterial microsome MUTAGENICITY TESTS, researchers often attempt to correlate the finding of carcinogenicity values and mutagenicity values.Cricetulus: A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research.Bone Marrow: The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Occupational Exposure: The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.Salmonella typhimurium: A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Bone Marrow Cells: Cells contained in the bone marrow including fat cells (see ADIPOCYTES); STROMAL CELLS; MEGAKARYOCYTES; and the immediate precursors of most blood cells.Carcinogens: Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.