Topic
Sister chromatid exchange
About: Sister chromatid exchange is a research topic. Over the lifetime, 3187 publications have been published within this topic receiving 90029 citations. The topic is also known as: replication-born DSB repair by SCE & GO:1990414.
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TL;DR: The present study is the first to report the genotoxic and cytotoxic effects of commercial formulation of α‐cypermethrin in peripheral blood lymphocytes.
Abstract: alpha-Cypermethrin, a highly active pyrethroid insecticide, is effective against a wide range of insects encountered in agriculture and animal husbandry The potential genotoxicity of a commercial formulation of alpha-cypermethrin (Fastac 100 EC, containing 10% alpha-cypermethrin as the active ingredient) on human peripheral lymphocytes was examined in vitro by sister chromatid exchange (SCE), chromosomal aberrations (CAs), and micronucleus (MN) tests The human lymphocytes were treated with 5, 10, 15, and 20 microg/ml of alpha-cypermethrin for 24- and 48-hr alpha-Cypermethrin induced SCEs and CAs significantly at all concentrations and treatment times and MN formation was significantly induced at 5 and 10 microg/ml of alpha-cypermethrin when compared with both the control and solvent control Binuclear cells could not be detected sufficiently in the highest two concentration of alpha-cypermethrin (15 and 20 microg/ml) for both the 24- and 48-hr treatment times alpha-Cypermethrin decreased the proliferation index (PI) at three high concentrations (10, 15, and 20 microg/ml) for both treatment periods as compared with the control groups In addition, alpha-cypermethrin reduced both the mitotic index (MI) and nuclear division index (NDI) significantly at all concentrations for two treatment periods The PI and MI were reduced by alpha-cypermethrin in a concentration-dependent manner during both treatment times In general, alpha-cypermethrin showed higher cytotoxic and cytostatic effects than positive control (MMC) at the two highest concentrations for the 24- and 48-hr treatment periods The present study is the first to report the genotoxic and cytotoxic effects of commercial formulation of alpha-cypermethrin in peripheral blood lymphocytes
50 citations
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TL;DR: The data indicate that chromatid and isochromatid deletions have different molecular steps in their formation, and that different molecular mechanisms are also involved in the symmetrical and unsymmetrical rejoining in Chromatid interchanges.
Abstract: Repair- and recombination-defective mutations at two loci (mei-9 and mei-41) of Drosophila melanogaster have been examined for their effects on the induction of chromosome aberrations by x-rays and the formation of sister chromatid exchanges (SCEs). Irradiation of larval neuroblast cells during the S phase with x-rays showed that mutants at both of these loci are about 10 times more sensitive than wild type to the induction of chromosome aberrations. The pattern of induced aberrations was characteristic for each mutant locus: in cells bearing mei-9 mutations most breaks were chromatid deletions, whereas in the presence of mei-41 mutations similar frequencies of chromatid and isochromatid deletions were observed. Furthermore, chromatid interchanges could not be induced in cells carrying mei-9 alleles; therefore these mutations define a step necessary for chromatid rejoining. mei-41 alleles also define a function involved in the formation of chromatid interchanges; total exchanges were less frequent than expected from nonmutant controls; and the proportion of exchanges arising by symmetrical rejoining was markedly reduced. These data indicate that chromatid and isochromatid deletions have different molecular steps in their formation, and that different molecular mechanisms are also involved in the symmetrical and unsymmetrical rejoining in chromatid interchanges. Neuroblast cells of larvae bearing mei-9 and mei-41 alleles were also treated for 13 hr with 5-bromodeoxyuridine at 9 μg/ml in order to differentiate sister chromatids for the scoring of SCEs. Whereas mei-41 had a normal level of SCEs, mei-9 exhibited a frequency of SCEs that was about 70% that of the control. Because both mei-9 and mei-41 mutations result in defective meiotic recombination, these data suggest that they define steps shared by symmetrical interchange formation and meiotic recombination that do not participate in the formation of most SCEs.
50 citations
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TL;DR: It is shown that hamster cells deficient in the Rad 51 paralog XRCC2, a component of the Rad51B/Rad51C/ Rad51D/XR CC2 complex, reveal a bias in favor of long-tract gene conversion (LTGC) during SCR.
Abstract: Sister chromatid recombination (SCR) is a potentially error-free pathway for the repair of DNA lesions associated with replication and is thought to be important for suppressing genomic instability. The mechanisms regulating the initiation and termination of SCR in mammalian cells are poorly understood. Previous work has implicated all the Rad51 paralogs in the initiation of gene conversion and the Rad51C/XRCC3 complex in its termination. Here, we show that hamster cells deficient in the Rad51 paralog XRCC2, a component of the Rad51B/Rad51C/Rad51D/XRCC2 complex, reveal a bias in favor of long-tract gene conversion (LTGC) during SCR. This defect is corrected by expression of wild-type XRCC2 and also by XRCC2 mutants defective in ATP binding and hydrolysis. In contrast, XRCC3-mediated homologous recombination and suppression of LTGC are dependent on ATP binding and hydrolysis. These results reveal an unexpectedly general role for Rad51 paralogs in the control of the termination of gene conversion between sister chromatids.
50 citations
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TL;DR: Genotoxic and antigenotoxic activities of carvacrol were investigated by the in vitro sister chromatid exchange (SCE) assay on human peripheral blood lymphocytes, indicating its potential for use as an antigenot toxic agent.
Abstract: Carvacrol is a predominant aromatic compound in oil of oregano. It has naturally remarkable antibacterial, antiviral, antifungal and antiparasital effects. In this study, genotoxic and antigenotoxic activities of carvacrol were investigated by the in vitro sister chromatid exchange (SCE) assay on human peripheral blood lymphocytes. The genotoxicity test was performed with carvacrol in two donors. On the other hand, inhibitory effect of carvacrol was tested in the presence of mitomycin C (MMC) in the same assay. According to data, all doses of carvacrol did not increase the formation of SCE, whereas it inhibited the rate of SCE induced by MMC. In conclusion, carvacrol exhibited a significant antigenotoxic activity in mammalian cells, indicating its potential for use as an antigenotoxic agent.
50 citations
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TL;DR: This work presents the first direct cytological evidence for the induction of true somatic recombination involving homologous chromosomes in chromosomes from Muntiacus muntjac fibroblasts and A9, a transformed mouse cell line.
Abstract: Mitomycin C-induced sister chromatic exchange and quadriradial formation were studied in chromosomes from Muntiacus muntjac fibroblasts and A9, a transformed mouse cell line. We present the first direct cytological evidence for the induction of true somatic recombination involving homologous chromosomes. Analysis of the quadriradials from Muntjac cells indicates a non-random distribution with respect to the chromosomes involved and with respect to the points of conjunction. Sister chromatid exchange and quadriradial formation may reflect the outcome of repair processes involving a high frequency of homologous exchanges in the interphase nucleus.
50 citations