Showing papers on "Sister chromatid exchange published in 2013"
TL;DR: Human diseases associated with malfunctioning of cohesin, albeit with mostly unperturbed sister chromatid cohesion, have been discussed.
121 citations
TL;DR: Overall, MWCNTs were shown to be genotoxic both in in vitro and in vivo tests; the mechanisms probably involve oxidative stress and inflammatory responses.
Abstract: The genotoxic effects of multi-walled carbon nanotubes (MWCNTs) were examined by using in vitro and in vivo assays. MWCNTs significantly induced micronuclei in A549 cells and enhanced the frequency of sister chromatid exchange (SCE) in CHO AA8 cells. When ICR mice were intratracheally instilled with a single dose (0.05 or 0.2 mg/animal) of MWCNTs, DNA damage of the lungs, analysed by comet assay, increased in a dose-dependent manner. Moreover, DNA oxidative damage, indicated by 8-oxo-7,8-dihydro-2¢-deoxyguanosine and heptanone etheno-deoxyribonucleosides, occurred in the lungs of MWCNT-exposed mice. The gpt mutation frequencies significantly increased in the lungs of MWCNT-treated gpt delta transgenic mice. Transversions were predominant, and G:C to C:G was clearly increased by MWCNTs. Moreover, many regions immunohistochemically stained for inducible NO synthase and nitrotyrosine were observed in the lungs of MWCNT-exposed mice. Overall, MWCNTs were shown to be genotoxic both in in vitro and in vivo tests; the mechanisms probably involve oxidative stress and inflammatory responses.
102 citations
TL;DR: This work demonstrates the existence of specific functions to guarantee SCR as the main repair event for replication-born DSBs that can occur by two pathways, one Rad51-dependent and the other Pol32-dependent.
Abstract: DNA double-strand breaks (DSBs) are harmful lesions that arise mainly during replication. The choice of the sister chromatid as the preferential repair template is critical for genome integrity, but the mechanisms that guarantee this choice are unknown. Here we identify new genes with a specific role in assuring the sister chromatid as the preferred repair template. Physical analyses of sister chromatid recombination (SCR) in 28 selected mutants that increase Rad52 foci and inter-homolog recombination uncovered 8 new genes required for SCR. These include the SUMO/Ub-SUMO protease Wss1, the stress-response proteins Bud27 and Pdr10, the ADA histone acetyl-transferase complex proteins Ahc1 and Ada2, as well as the Hst3 and Hst4 histone deacetylase and the Rtt109 histone acetyl-transferase genes, whose target is histone H3 Lysine 56 (H3K56). Importantly, we use mutations in H3K56 residue to A, R, and Q to reveal that H3K56 acetylation/deacetylation is critical to promote SCR as the major repair mechanism for replication-born DSBs. The same phenotype is observed for a particular class of rad52 alleles, represented by rad52-C180A, with a DSB repair defect but a spontaneous hyper-recombination phenotype. We propose that specific Rad52 residues, as well as the histone H3 acetylation/deacetylation state of chromatin and other specific factors, play an important role in identifying the sister as the choice template for the repair of replication-born DSBs. Our work demonstrates the existence of specific functions to guarantee SCR as the main repair event for replication-born DSBs that can occur by two pathways, one Rad51-dependent and the other Pol32-dependent. A dysfunction can lead to genome instability as manifested by high levels of homolog recombination and DSB accumulation.
84 citations
TL;DR: Ctf4 and Chl1 delineate an additional acetylation-independent pathway that might hold important clues as to the mechanism of sister chromatid cohesion establishment, and show that each of these factors facilitates cohesin acetylations.
Abstract: Cohesion between sister chromatids, mediated by the chromosomal cohesin complex, is a prerequisite for their alignment on the spindle apparatus and segregation in mitosis Budding yeast cohesin first associates with chromosomes in G1 Then, during DNA replication in S-phase, the replication fork-associated acetyltransferase Eco1 acetylates the cohesin subunit Smc3 to make cohesin’s DNA binding resistant to destabilization by the Wapl protein Whether stabilization of cohesin molecules that happen to link sister chromatids is sufficient to build sister chromatid cohesion, or whether additional reactions are required to establish these links, is not known In addition to Eco1, several other factors contribute to cohesion establishment, including Ctf4, Ctf18, Tof1, Csm3, Chl1 and Mrc1, but little is known about their roles Here, we show that each of these factors facilitates cohesin acetylation Moreover, the absence of Ctf4 and Chl1, but not of the other factors, causes a synthetic growth defect in cells lacking Eco1 Distinct from acetylation defects, sister chromatid cohesion in ctf4Δ and chl1Δ cells is not improved by removing Wapl Unlike previously thought, we do not find evidence for a role of Ctf4 and Chl1 in Okazaki fragment processing, or of Okazaki fragment processing in sister chromatid cohesion Thus, Ctf4 and Chl1 delineate an additional acetylation-independent pathway that might hold important clues as to the mechanism of sister chromatid cohesion establishment
74 citations
TL;DR: It is suggested that, although BLM is downregulated in G1 phase in order to promote NHEJ-mediated DNA repair, it is stabilized by TopBP1 in S phase cells inorder to suppress SCE and thereby prevent genomic instability.
59 citations
TL;DR: Findings indicate that magnetite nano-particles induce ROS in mammalian cells, leading to the direct or indirect induction of DSB, followed by clastogenic events including MN and SCE.
Abstract: We examined the genotoxicity of magnetite nanoparticles (primary particle size: 10 nm) on human A549 and Chinese hamster ovary (CHO) AA8 cells. Six hours' treatment with the particles dose-dependently increased the frequency of micronuclei (MN) in the A549 and CHO AA8 cells up to 5.2% and 5.0% at a dose of 200 µg/ml (34 µg/cm²), respectively. In A549 cells, treatment with the nano-particles (2 µg/ml) for 1 hr induced H2AX phosphorylation, which is suggestive of DNA double strand breaks (DSB). Treating CHO AA8 cells with 2 µg/ml (0.34 µg/cm²) magnetite for 1 hour resulted in a five times higher frequency of sister chromatid exchange (SCE) than the control level. We detected reactive oxygen species (ROS) in CHO cells treated with the particles. These findings indicate that magnetite nano-particles induce ROS in mammalian cells, leading to the direct or indirect induction of DSB, followed by clastogenic events including MN and SCE.
36 citations
TL;DR: The current data indicating the induction of CA by nicotine underscore the necessity of ongoing investigations on the potential of nicotine to initiate mutagenesis and tumour promotion, particularly the long-term use of nicotine should be critically discussed.
Abstract: The role of the tobacco-alkaloid nicotine in tumour biology is widely discussed in the literature. Due to a strong capacity to induce angiogenesis, a pro-mutagenic potential in non-tumour and cancer cells, and a pro- and anti-apoptotic influence, nicotine seems to promote the growth of established tumours. However, results indicating DNA damage and genetic instability associated with nicotine have been contradictory thus far. A variety of markers and endpoints of genotoxicity are required to characterize the genotoxic potential of nicotine. Induction of DNA single- and double-strand breaks, the formation of micronuclei, and the induction of sister chromatid exchange and chromosome aberrations represent possible genotoxicological endpoints at different cellular levels. Human lymphocytes were exposed to nicotine concentrations between 1μM and 1mM for 24h in vitro. The comet assay, the cytokinesis-block micronucleus test, the chromosome aberration (CA) test, and the sister chromatid exchange (SCE) test were then applied. Viability and apoptosis were measured by flow cytometry in combination with the annexin V-propidium iodide staining test. In this test setting, no enhanced DNA migration was measured by the comet assay. An increase in the micronucleus frequency was detected at a concentration of 100μM nicotine without affecting the frequency of apoptotic cells. A distinct genotoxic effect was determined by the CA test and the SCE test, with a significant increase in CA and SCE at a concentration of 1μM. In the annexin V test, nicotine did not influence the proportion of apoptotic or necrotic cells. The current data indicating the induction of CA by nicotine underscore the necessity of ongoing investigations on the potential of nicotine to initiate mutagenesis and tumour promotion. Taking into account the physiological nicotine plasma levels in smokers or in nicotine-replacement therapy, particularly the long-term use of nicotine should be critically discussed.
36 citations
TL;DR: Cytotoxic indexes (Mitotic and Proliferation Index) showed that the lowest concentrations could enhance the cell proliferation rates and the highest ones could negatively affect to human peripheral lymphocytes growth.
33 citations
TL;DR: Investigation of the modulatory effects of APG on human lymphocytes after irradiation with gamma rays or treatment with the antineoplastic agent, mitomycin C, in vitro found no significant differences in the frequency of CAs or micronuclei in human peripheral blood lymphocytes irradiated with Gamma rays and then post-treated with APG.
Abstract: Apigenin (APG), a flavone, is known to exhibit antioxidant, antimutagenic and antitumorigenic activity, both in vivo and in vitro. The aim of this study is to investigate the modulatory effects of APG on human lymphocytes after irradiation with gamma rays (3 Gy) or treatment with the antineoplastic agent, mitomycin C (MMC), in vitro. Cytogenetic biomarkers such as chromosome aberrations (CAs), sister chromatid exchanges (SCEs) and cytochalasin-B blocked micronuclei (CBMN), were studied in blood lymphocytes treated with radiation, or antineoplastic agent (MMC), and APG. Whole blood lymphocytes were cultured in vitro using a standard protocol. No significant differences were found in the frequency of CAs or micronuclei (MN) in human peripheral blood lymphocytes irradiated with gamma rays (3 Gy) and then posttreated with APG. There was an increase in the frequency of SCEs per cell in APG-treated samples compared with the controls. Lymphocytes treated with MMC in the presence of APG exhibited a significant decrease (P< 0.01) in the frequency of SCEs compared with MMC treatment alone. The data for the MN test indicated that APG treatment significantly reduced (P < 0.01) the frequency of MMC-induced MN.
23 citations
TL;DR: Evidence is provided that Aurora B kinase directly targets Ssu72 phosphatase for regulation of sister chromatid cohesion during early mitosis, and overexpression of the Aurora B-mediated phosphomimetic mutant of SSu72 prevents maintainance chromosome arm cohesion.
Abstract: Cohesins establish cohesion between replicated sister chromatids and are maintained as a multiprotein complex on chromosome arms until they are phosphorylated by mitotic kinases, such as Aurora B and Plk1. However, the mechanics of how the phosphorylation and dephosphorylation of cohesin subunits by kinases and phosphatases, respectively, leads to the dissociation of the cohesin complex from chromosomes remain unclear. Here we report that Aurora B kinase directly interacts with and phosphorylates Ssu72, a new cohesin-binding phosphatase, at Ser 19 in vitro and in vivo. The Aurora B-mediated phosphorylation of Ssu72 causes the structural modification of Ssu72 protein, downregulates phosphatase activity and triggers the ubiquitin-dependent degradation of Ssu72. Overexpression of the Aurora B-mediated phosphomimetic mutant of Ssu72 prevents maintainance chromosome arm cohesion. These results provide evidence that Aurora B kinase directly targets Ssu72 phosphatase for regulation of sister chromatid cohesion during early mitosis.
21 citations
TL;DR: It is reported that an evolutionarily conserved protein Pat1 is a structural component of Saccharomyces cerevisiae kinetochore and associates with centromeres in a NDC10-dependent manner.
Abstract: The kinetochore (centromeric DNA and associated protein complex) is essential for faithful chromosome segregation and maintenance of genome stability. Here we report that an evolutionarily conserved protein Pat1 is a structural component of Saccharomyces cerevisiae kinetochore and associates with centromeres in a NDC10-dependent manner. Consistent with a role for Pat1 in kinetochore structure and function, a deletion of PAT1 results in delay in sister chromatid separation, errors in chromosome segregation, and defects in structural integrity of centromeric chromatin. Pat1 is involved in topological regulation of minichromosomes as altered patterns of DNA supercoiling were observed in pat1Δ cells. Studies with pat1 alleles uncovered an evolutionarily conserved region within the central domain of Pat1 that is required for its association with centromeres, sister chromatid separation, and faithful chromosome segregation. Taken together, our data have uncovered a novel role for Pat1 in maintaining the structural integrity of centromeric chromatin to facilitate faithful chromosome segregation and proper kinetochore function.
TL;DR: Evaluated the cytogenetic damage induced by AA and GA in cultured human lymphocytes by use of the sister chromatid exchange (SCE) assay and suggested associations between the induction of SCEs with GSTP1 (Ile105Val) and GSTA2 (Glu210Ala) genotypes are suggested.
Abstract: Acrylamide (AA) is a probable human carcinogen generated in carbohydrate-rich foodstuffs upon heating. Glycidamide (GA), formed via epoxidation, presumably mediated by cytochrome P450 2E1, is considered to be the active metabolite that plays a central role in the genotoxicity of AA. The aim of this work was to evaluate the cytogenetic damage induced by AA and GA in cultured human lymphocytes by use of the sister chromatid exchange (SCE) assay. Furthermore, this report addresses the role of individual genetic polymorphisms in key genes involved in detoxification and DNA-repair pathways (BER, NER, HRR and NHEJ) on the induction of SCE by GA. While AA induced the number of SCE/metaphase only slightly, especially for the highest concentration tested (2000 μM), GA markedly induced SCEs in a concentration-dependent manner up to concentrations of 750 μM, leading to an increase in SCEs of up to about 10-fold compared with controls. By combining DNA damage in GA-treated lymphocytes and data on polymorphisms, associations between the induction of SCEs with GSTP1 (Ile105Val) and GSTA2 (Glu210Ala) genotypes are suggested.
TL;DR: The sister chromatid exchange (SCE) test makes it possible to detect chromosome instability that corresponds with elevated vulnerability of the organism to genotoxic factors of a mutagenic and carcinogenic nature.
TL;DR: The results suggest that storax balsam can be used as an alternative antibacterial and antipathogenic agent due to its cytotoxic and genotoxic effects.
Abstract: The aim of this study is to investigate the effects of the storax balsam, which is a kind of sweet gum obtained from the Liquidambar orientalis Mill trees, on cell viability, cytotoxicity and genotoxicity in human lymphocyte in vitro. We studied the genotoxic effects of the extract of storax balsam (SE) using sister chromatid exchange (SCE) test system. Also the cytotoxic and inhibitory effects on cell proliferation of SE were evaluated using lactate dehydrogenase (LDH) assay and cell proliferation (WST-1) assay. The SCE frequency was increased when the cells were treated with 1.6 and 4.0 µg/mL SE concentrations (p < 0.05). Moreover, treatment of the cells with the same concentrations significantly depleted the cell number at 24th and 48th hours and elevated the LDH levels (p < 0.05) at 48th hour. These results suggest that SE can be used as an alternative antibacterial and antipathogenic agent due to its cytotoxic and genotoxic effects.
TL;DR: Investigation of genotoxicity in lymphocytes from patients with iron deficiency anemia using chromosomal aberrations and sister chromatid exchanges assays demonstrated that IDA has a differential effect on the frequency of spontaneous CAs and SCEs.
Abstract: Previous studies have shown that iron deficiency anemia is associated with oxidative stress produced by a decrease in antioxidant enzyme activities and/or a high level of oxidants. Because oxidative stress induces DNA damage, we investigated genotoxicity in lymphocytes from patients with iron deficiency anemia (IDA) using chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs) assays. Eighteen IDA subjects and a similar number of age-matched healthy controls were included in the study. The results demonstrated that IDA was associated with a slight increase in the frequency of spontaneous CAs and a decrease in the frequency of SCEs (P
TL;DR: Investigation of the genetic effects of resveratrol at concentrations of 10, 15, 25, 40, 75 and 100 µM revealed that PM-induced increases in the mean frequencies of both genotoxic indices were diminished by RSV in a clear dose dependent manner, indicating its protective role towards the cells from PM exerted injury.
Abstract: The aim of this work was to investigate the genetic effects of resveratrol (RSV) at concentrations of 10, 15, 25, 40, 75 and 100 µM and its activities on the genotoxicity induced by the permethrin (PM) (200 µM). After the application of PM and RSV, separately and together, cultured human lymphocytes were assessed by chromosome aberrations (CA) and sister chromatid exchange (SCE) tests. According to results, the frequencies of CA and SCE rates in the peripheral lymphocytes were significantly increased by PM compared with the controls. However, RSV had no genotoxic effect. Furthermore, the findings revealed that PM-induced increases in the mean frequencies of both genotoxic indices were diminished by RSV in a clear dose dependent manner, indicating its protective role towards the cells from PM exerted injury. In conclusion, these effects of RSV should be considered while evaluating the possible use of RSV as a therapeutic agent.
TL;DR: The results suggest that PMX has a potent cytotoxic effect against human peripheral blood lymphocytes at concentrations which are reached in vivo in the blood plasma.
Abstract: Pemetrexed (PMX) is an antineoplastic antifolate used in the treatment of non-small cell lung cancer, mesothelioma and several types of neoplasms. Its toxicity in tumor cells has been linked with the potent inhibition of thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase, and subsequent depletion of both purine and pyrimidine nucleotides. However, cytogenetic toxicity of PMX in non-diseased cells has not been adequately studied; despite the increasing data on the DNA-damaging potential of antineoplastic agents on normal cells. In the present study, the genotoxic potential of PMX was evaluated in peripheral blood lymphocytes obtained from healthy human subjects using chromosome aberration (CA), sister chromatid exchange (SCE) and micronucleus (MN) assays as the cytogenetic damage markers. Human peripheral blood lymphocytes were exposed to four different concentrations (25, 50, 75 and 100 μg/mL) of PMX for 24- and 48-h treatment periods. PMX significantly increased the formation of CA in 24-h treatment, but not in 48-h treatment. PMX did not increase the mean SCE frequency in 24- and 48-h treatment periods; however, there was a striking increase (although not statistically significant, p > 0.05) in the number of SCEs at 25 μg/mL (24- and 48-h treatment) and 50 μg/mL (24-h treatment) due to an increase of SCE at the single-cell level. Interestingly, PMX did not induce MN formation in either 24- or 48-h treatment periods. PMX strongly decreased the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) in 24- and 48-h treatment periods. Our results suggest that PMX has a potent cytotoxic effect against human peripheral blood lymphocytes at concentrations which are reached in vivo in the blood plasma.
TL;DR: Results indicated that Xpa, Xpc, Brca2, Rad51, Xrcc2, Chek1, and Hus1 were essential for the BM-MSCs to counteract the effects of FA.
Abstract: In this study, we assessed the toxic effects of formaldehyde (FA) on mouse bone marrow mesenchymal stem cells (BM-MSCs). Cytotoxicity was measured by using MTT assay. DNA strand breakage was detected by standard alkaline comet assay and comet assay modified with proteinase K (PK). DNA-protein crosslinks (DPCs) were detected by KCl-SDS precipitation assay. We found that FA at a concentration from 75 to 200 μM inhibited cell survival and induced DPCs over 125 μM. The PK-modified comet assay showed that FA-induced DNA strand breakage was increased in a dose-dependent manner from 75 to 200 μM. On the other hand, standard alkaline comet assay showed that DNA strand breakage was decreased with FA concentration over 125 μM. We confirmed by using Pearson correlation that there was a negative linear correlation between DPCs and survival rate (r = -0.987, P < 0.01) and positive linear relationships between DPCs and (i) sister chromatid exchange and (ii) micronucleus (r = 0.995, P < 0.01; r = 0.968, P < 0.01). DNA damage RT(2) profiler polymerase chain reaction array was used to investigate the changes in the expression of damage response genes. Xpa and Xpc of the nucleotide excision repair pathway and Brca2, Rad51, and Xrcc2 of the homologous recombination pathway were all up-regulated in both 75 and 125 μM FA. However, the same genes were down-regulated with 175 μM FA. The expressions of Chek1 and Hus1, which are involved in cell cycle regulation, were altered in the same manner with 75, 125, and 175 μM FA. These results indicated that Xpa, Xpc, Brca2, Rad51, Xrcc2, Chek1, and Hus1 were essential for the BM-MSCs to counteract the effects of FA.
TL;DR: Increased SCE and the occurrence of micronuclei, as well as a reduced PRI, are associated with breast cancer and suggest that they exhibit greater genetic instability than women of the same age.
Abstract: Purpose
The aim of this study was to evaluate and compare the rate of sister chromatid exchange (SCE), the occurrence of micronuclei, and the lymphocyte proliferation rate index (PRI) in patients with breast cancer, their first-degree relatives, and healthy volunteers.
TL;DR: FANCD2 may promote spontaneous SCE by influencing which double-strand break repair pathway predominates during normal S-phase progression, which is consistent with a model where spontaneous S CEs are the end product of endogenous recombination events.
Abstract: Uveal melanoma (UM) is unique among cancers in displaying reduced endogenous levels of sister chromatid exchange (SCE). Here we demonstrate that FANCD2 expression is reduced in UM and that ectopic expression of FANCD2 increased SCE. Similarly, FANCD2-deficient fibroblasts (PD20) derived from Fanconi anaemia patients displayed reduced spontaneous SCE formation relative to their FANCD2-complemented counterparts, suggesting that this observation is not specific to UM. In addition, spontaneous RAD51 foci were reduced in UM and PD20 cells compared with FANCD2-proficient cells. This is consistent with a model where spontaneous SCEs are the end product of endogenous recombination events and implicates FANCD2 in the promotion of recombination-mediated repair of endogenous DNA damage and in SCE formation during normal DNA replication. In both UM and PD20 cells, low SCE was reversed by inhibiting DNA-PKcs (DNA-dependent protein kinase, catalytic subunit). Finally, we demonstrate that both PD20 and UM are sensitive to acetaldehyde, supporting a role for FANCD2 in repair of lesions induced by such endogenous metabolites. Together, these data suggest FANCD2 may promote spontaneous SCE by influencing which double-strand break repair pathway predominates during normal S-phase progression.
TL;DR: More exposed to the effect of environmental pollutants, the horses from the urban environment developed more double and triple SCEs in comparison with the village horses, and the urban horses also developed quadruple S CEs, in addition to the less frequent exchanges.
Abstract: The SCE test is often used as a sensitive and reliable technique in the biomonitoring of genotoxicity of mutagenic and carcinogenic agents. This study analysed the frequency of sister chromatid exchange in domestic horse chromosomes depending on the habitat and age of the analysed horses. The chromosome preparations were obtained from an in vitro culture of peripheral blood lymphocytes stained using the FPG technique. Both the habitat and the age significantly influence SCE frequency. A higher SCE incidence was observed in horses that lived in a large urban agglomeration than in those from the country. Also, a higher SCE incidence was identified in the group of horses above 6 years of age in comparison with the younger ones. Additionally, the frequency of SCEs in the first, second and third chromosomes and the X sex chromosome were analysed in detail. More exposed to the effect of environmental pollutants, the horses from the urban environment developed more double and triple SCEs in comparison with the village horses. The urban horses also developed quadruple SCEs, in addition to the less frequent exchanges.
TL;DR: The Tlox system provides a new genetic tool to track clonal expansion within a defined cell population or tissue type in live animals.
Abstract: Tracking and isolating live cells based on their proliferative history in live animals remains a technical challenge in animal studies. We have designed a genetic marking system for tracking the proliferative frequency and history of lymphocytes during their development and homeostatic maintenance. This system is based on activation of a fluorescent marker after Cre-dependent recombination between sister chromatids at a specially designed tandem loxP site, named Tlox. We have demonstrated the utility of the Tlox system in tracking proliferative windows of B and T lymphocyte development. We have further applied the Tlox system in the analysis of the proliferative behavior and homeostatic maintenance of Vγ1.1 positive γδ T cells. Our data show that Vγ1.1 T cells generated in neonatal but not adult life are able to expand in the thymus. The expanded Vγ1.1 T cells are preferentially maintained in the liver but not in lymphoid organs. It has been shown that numbers of Vγ1.1 T cells were dramatically increased in the lymphoid organs of Id3 deficient mice. By combining BrdU and Tlox assays we show that this phenotype is primarily due to enhanced neonatal expansion and subsequent retention of Vγ1.1 T cells. Thus, the Tlox system provides a new genetic tool to track clonal expansion within a defined cell population or tissue type in live animals.
TL;DR: It is suggested that the principal mechanism for polyalanine expansions (and contractions) is slipped mispairing without repair or that the true frequency of unequal sister chromatid exchange involving these repeats is low.
Abstract: Polyalanine repeat expansion diseases are hypothesized to result from unequal chromosomal recombination, yet mechanistic studies are lacking. We identified two de novo cases of hand-foot-genital syndrome (HFGS) associated with polyalanine expansions in HOXA13 that afforded rare opportunities to investigate the mechanism. The first patient with HFGS was heterozygous for a de novo nine codon polyalanine expansion. Haplotype investigation showed that the expansion arose on the maternally inherited chromosome but not through unequal crossing over between homologs, leaving unequal sister chromatid exchange during mitosis or meiosis or slipped mispairing as possible explanations. The asymptomatic father of the second patient with HFGS was mosaic for a six codon polyalanine expansion. Multiple tissue PCR and clonal analysis of paternal fibroblasts showed only expansion/WT and WT/WT clones, and haplotype data showed that two unaffected offspring inherited the same paternal allele without the expansion, supporting a postzygotic origin. Absence of the contracted allele in the mosaic father does not support sister chromatid exchange in the origin of the expansion. Mosaicism for HOXA13 polyalanine expansions may be associated with a normal phenotype, making examination of parental DNA essential in apparently de novo HFGS cases to predict accurate recurrence risks. We could not find an example in the literature where unequal sister chromatid exchange has been proven for any polyalanine expansion, suggesting that the principal mechanism for polyalanine expansions (and contractions) is slipped mispairing without repair or that the true frequency of unequal sister chromatid exchange involving these repeats is low.
TL;DR: Findings show that copper exhibits a genotoxic and mutagenic potential in rabbits.
Abstract: This study was carried out to determine the genotoxic effects of oral application of CuSO 4 in rabbits by the chromosome aberration (CA) and sister chromatid exchange (SCE) tests. Ten male New Zealand rabbits (5 months old, weighing 3.5-4.0 kg) were allocated into two groups. The first group received CuSO 4 (5H2O) in drinking water for 6 con- secutive days. The second group was used as a control. On the 7 th day, blood samples were taken from the ear marginal vein and the SCE and CA tests in peripheral lymphocytes were used as genotoxicity and mutagenicity endpoints, respectively. Results showed a significant increase in the frequencies of the aberrant cells (7.4±0.24, P<0.001) and CA (chromatid frag- ments 3.2±0.37, chromosome fragments 4.2±0.37, P<0.001), and total aberrations (7.4±0.24, P<0.001) after the treatment with CuSO4 when compared with the control group. The level of SCE per cell in the CuSO4-treated rabbits (9.66±0.062) was significantly higher than in rabbits from the control group. These findings show that copper exhibits a genotoxic and mutagenic potential in rabbits.
TL;DR: Alcoholic extracts of C. bonducella were tested for their antimutagenic and anticarcinogenic properties and significantly reduced the number of aberrant cells and frequency of aberrations per cell in in vivo.
Dissertation•
31 May 2013
TL;DR: The aim of this book is to provide a systematic review of the current literature on chromosomal aberrations and its role in cancer, as well as some of the mechanisms behind its development.
Abstract: i Resumo iii List of publications and communications v Table of contents ix List of Figures xv List of Tables xvii Abbreviations xix Chapter 1 – General Introduction 1 1.1. Causes of Cancer 3 1.1.1. Principles 3 1.1.2. Food contaminants 5 1.2. Biomarkers of genetic DNA damage 8 1.2.1. Principles 8 1.2.2. Biomarker of exposure 9 1.2.2.1. Biomarkers of internal dose 10 1.2.2.2. Biomarkers of effective dose 10 1.2.3. Biomarkers of effects 12 1.2.3.1. Micronucleus (MN) 13 1.2.3.2. Chromosomal aberrations (CAs) 13 1.2.3.3. Sister Chromatid Exchange (SCE) 14 1.2.3.4. Comet assay 15 1.2.4. Biomarker of susceptibility 16
TL;DR: The results showed a statistically significant increase in chromosomal aberrations and sister chromatid exchange in the exposed persons in comparison to controls, suggesting that exposure to waste anaesthetic gases has the potential to cause changes in human genome.
TL;DR: The incidence of unstable chromosome aberrations in peripheral blood lymphocytes from unirradiated control subjects was analyzed using cytogenetic data obtained from 9 cytogenetics laboratories located in Moscow, St.-Petersburg, Obninsk, and Dubna (Russia).
Abstract: The incidence of unstable chromosome aberrations in peripheral blood lymphocytes from unirradiated control subjects was analyzed using cytogenetic data obtained from 9 cytogenetic laboratories located in Moscow, St.-Petersburg, Obninsk, and Dubna (Russia). The objective of this study was to estimate the level and spectrum of spontaneous chromosome aberrations in human lymphocytes. 1140 blood samples were taken from 1112 subjects (594 men and 546 women) aged 1 to 72. The total metaphase number was 466795. The uniform Giemsa method for peripheral blood lymphocyte cultures was used. After counting 466795 metaphases, 4288 chromosomal aberrations of various types were classified. The most frequent types of aberrations were acentrics and chromatid deletions. They made up 90% of the total number of aberrations. The remaining 10% were exchange aberrations. The number of chromosome exchanges (dicentrics and centric rings) was twice the number of chromatid exchanges. Overall, the portion ofcells with chromosomal or (and) chromatid aberrations was 0.89 +/- 0.01%; the frequency of acentrics was 0.29 +/- 0.01; the frequency of dicentrics was 0.046 +/- 0.003; the frequency of unstable chromosome aberrations was 0.35 +/- 0.01; and the frequency of chromatid aberrations was 0.57 +/- 0.01 per 100 cells.
TL;DR: Results have shown that all treatments with EEPIR could induce cell cycle delay as shown by significant increase in the number of metaphase cells in the first cell cycle but neither in the second nor the third cell cycle, which could serve its potential therapeutic effects, especially as an anticancer agent.
Abstract: In Thai traditional medicine, Plumbago indica or Jetamul-Pleung-Dang in Thai is known to have health benefit especially for anti-inflammatory, antibacterial, and antitumor activities. However, the mechanisms of its action are still uncertain. One of which might be genotoxic effects. In the present study, we investigated the genotoxicity of an ethanolic extract of Plumbago indica root (EEPIR) by sister chromatid exchange (SCE) assay in human lymphocytes. Results have shown that all treatments with EEPIR (12.5-100 µg/ml) could induce cell cycle delay as shown by significant increase in the number of metaphase cells in the first cell cycle but neither in the second nor the third cell cycle. Only at concentrations of 25, 50, and 100 µg/ml were SCE levels significantly increased above that of the control (p<0.05) . EEPIR at a concentration of 500 µg/ml induced cell death as few mitotic cells were shown. Accordingly, EEPIR (25-100 µg/ml) is genotoxic in human lymphocytes and cytotoxic at concentrations of ≥500 µg/ml in vitro. Therefore, these activities of the EEPIR could serve its potential therapeutic effects, especially as an anticancer agent. Further study of EEPIR in vivo is now needed to support this in vitro evidence.
TL;DR: It is concluded that although, WB exerts potential genotoxic effects in cultured lymphocytes, its cytogenetic effects are very unlikely to occur in blood cultures of WB-administered subjects.
Abstract: Introduction: Wellbutrin (bupropion hydrochloride; WB), an anti-depressant of the aminoketone class is new highly selective norepinephrine and dopamine reuptake inhibitor; it is effective in the treatment of patients with major depression. Materials and Methods: To investigate the in vitro effects of WB in human cultured peripheral blood lymphocytes and human cortical neural (HCN2) cell lines, micronucleus, sister chromatid exchange analysis, cellular viability, and comet assays were employed. The present study is to our knowledge, the first report on WB genotoxicity in cultured human peripheral blood lymphocytes and its cytotoxicity in the HCN2 cell line. We have also investigated the genotoxic potential of WB to induce chromosomal aberrations. Results: WB-induced cytotoxicity (measured as reduction of the nuclear division index) possibly prevented the division of damaged cells. Conclusion: We conclude that although, WB exerts potential genotoxic effects in cultured lymphocytes, its cytogenetic effects are very unlikely to occur in blood cultures of WB-administered subjects.