Theory of In-Vitro Chromosomal Aberrations Experiment
In genetics, genotoxicity describes the property of chemical agents that damages the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, whereas not all genotoxic substances are mutagenic. The alteration can have direct or indirect effects on the DNA: the induction of mutations, mistimed event activation, and direct DNA damage leading to mutations. The permanent, heritable changes can affect either somatic cells of the organism or germ cells to be passed on to future generations. Cells prevent expression of the genotoxic mutation by either DNA repair or apoptosis; however, the damage may not always be fixed leading to mutagenesis.
Principle of In-Vitro Chromosomal Aberrations Virtual Experiment
In the in-vitro chromosomal aberrations test, the presence of genotoxic agents in the environment may cause, through different mechanisms, chromosomal mutations, which are associated with the induction of both heritable defects as well as cancer in human population. Chromosomal mutations are distinguished under two major categories related to changes in the chromosome structure (chromosomal aberrations) and changes in the number of chromosomes (numerical aberrations). Structural chromosome aberrations are induced by physical and chemical mutagenic agents through a variety of molecular mechanisms, which are almost exclusively a consequence of a direct damage to DNA (e.g., DNA strand breaks, base damage, hydrolysis of bases, pyrimidine dimers, DNA cross-links) or indirect (e.g., inhibition of DNA topoisomerases I and II, nucleotide pool imbalance, generation of reactive oxygen species) left unrepaired, or misrepaired to produce chromosome breaks or rearrangements. This in vitro assay aimed to detect structural chromosomal aberrations by estimating different classes of chromosome changes scored in metaphase using the light microscope. Chromosomal aberrations are based on whether one or both chromatids (at the same locus) in a metaphase chromosome is involved in an aberration.
