Recombination Sister-chromatid exchange

Mitomycin C was found to have broad activity against a range of tumors and has been used clinically since the early 1960s [14, 15]. It causes many specific cellular effects, including inhibition of DNA synthesis, recombination, chromosome breakage, sister chromatid exchange, induction of DNA repair, and induction of... 

The term genotoxicity is a broader term and refers to potentially harmful effects on genetic material, which are not necessarily associated with mutagenicity. Thus, tests for genotoxicity include tests, which provide an indication of induced damage to DNA (but not direct evidence of mutation) via effects such as unscheduled DNA synthesis (UDS), sister chromatid exchange (SCE), DNA strand breaks, DNA adduct formation or mitotic recombination, as well as tests for mutagenicity. ... 

Fortunately, a number of in situ, short-term bioassays to detect genotoxic and related effects have become available. These include a variety of measured endpoints such as aneuploids, chromosal aberrations, DNA damage, dominant lethal mutation, gene mutation, inhibition of intercellular communication, micronuclei, mitotic recombination and gene conversions, and sister chromatid exchange and cell transformation (IARC, 1989). A detailed discussion of these tests is beyond the scope of this book. However, such tests are important from our perspective as atmospheric chemists because, as we shall see, they can be used to detect biologically active compounds in very complex mixtures, and hence serve to focus chemical analysis efforts (IARC, 1989, p. 20). We emphasize in advance the... 

Epoxybutane induced morphological transformation, sister chromatid exchanges, chromosomal aberrations and mutation in cultured animal cells however, in a single study, it did not induce unscheduled DNA synthesis in rat primary hepatocytes. It induced sex-linked recessive lethal mutations and translocations in Drosophila melanogaster, mitotic recombination in yeast, and mutations in yeast and fungi. 1,2-Epoxybutane induced DNA damage and mutations in bacteria. 

Propanc sultone causes DNA damage and mutation in bacteria and induces mitotic recombination in yeast. It induces mutations and chromosomal aberrations in plant cells. In cultured mammalian cells, it induces chromosomal aberrations, sister chromatid exchanges and, according to single studies, cell transfonnation in C3H lOT /z cells, but not in Syrian hamster embryo cells. DNA strand breaks are induced in brain cells from rats injected with 1,3-propane sultone. 

As previously summarized, diethyl sulfate induced mutation and DNA damage in bacteria and induced reverse mutation and mitotic recombination in yeast. In plant cells, diethyl sulfate induced chromosomal aberrations. In a single study, diethyl sulfate did not induce heritable translocation in Drosophila melanogaster but did induce autosomal recessive lethal mutations, sex-linked recessive lethal mutations and genetic crossing-over. In cultured mammalian cells, diethyl sulfate induced chromosomal aberrations, mieronueleus formation, sister chromatid exchanges, forward mutation and DNA singlestrand breaks it also induced unscheduled DNA synthesis in primary cultures of rat... 

Therefore, the genetic lesions caused by a mutagen can be detected in assays for many genetic end points, including base-pair substitution and frameshift mutation, deletion, mitotic recombination or gene conversion, unscheduled DNA synthesis, sister chromatid exchange, and chromosomal aberration.170... 

See also Ames Test Carcinogenesis Chromosome Aberrations Dominant Lethai Tests In HfroTest In Vivo Test Moiecuiar Toxicoiogy-Recombinant DNA Tech-noiogy Mouse Lymphoma Assay Sister Chromatid Exchanges Toxicity Testing, Aiternatives. 

Sonda E, Sasaki M, Morrison C, et al. (1999) Sister chromatid exchanges are mediated by homologous recombination in vertebrate cells. Molecular Cell Biology 19 5166-5169. 

In vitro DMA damage and repair, including DNA adducts, single-strand breaks Unscheduled DNA synthesis Mitotic recombination in Saccharomyces cerevislae Sister chromatid exchange... 

Purpose. The purpose of the sister chromatid exchange (SCE) assay is to evaluate the potential of the test substance to induce repair of DNA lesions by homologous recombination in cells of treated animals (potentially all species, usually rodents) (Latt et al. 1981 Helleday 2003). It can easily be applied to any dividing tissue, such as bone marrow and peripheral blood, from which cell suspensions can be isolated and analyzed. 

As reviewed by the NTP (2000), naphthalene has been shown to cause sister chromatid exchanges (SCEs) and chromosomal aberrations in Chinese hamster ovary cells, micronuclei (MNs) in human lymphoblastoid MCL-5 cells, and somatic mutations and recombination in Drosophila. Naphthalene was not mutagenic in Salmonella, nor did it induce DNA damage in E. coli (as reviewed by NTP 2000). 

Amplification of genes under selective conditions has been widely observed-for example, in development of pesticide-resistant forms of insects. Such amplified structures could arise either through recombination with unequal sister-chromatid exchange, schematized in Figure 25.41, or by a conservative transposition process. Later, homologous recombination within an amplified region can lead to excision of sequences containing one or more amplified sequences. In order to replicate autonomously, these excised sequences must have a centromere. Such elements probably represent the double-minute chromosomes. 

Chlorpyrifos is not mutagenic, as judged by mitotic recombination assays, and did not increase sister chromatid exchange above background in tests with chick (Gallus spp.) embryos and Chinese hamster (Cricetus spp.) ovary cells. Chlorpyrifos altered serum cortisol and decreased thyroxine concentrations in sheep given oral doses of 12.5 mg chlor-pyrifos g BW twice weekly for 43 days, indicting a need for more research on the role of chlorpyrifos in hormone metabolism. 

Dose-dependent induction of chromosomal aberrations and sister chromatid exchanges were observed in human lymphocytes treated with dill leaf or seed essential oil. No significant effects of dill seed essential oil were observed in the Drosophila melanogaster somatic mutation and recombination test (SMART) in vivo (Lazutka et al. 2001). 

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