Relationship between DNA damage and micronucleus in mouse liver

To determine the optimum timing of partial hepatectomy (PH) in a previously developed mouse liver micronucleus test (Igarashi and Shimada, 1997), the relation between DNA damage and micronucleus was examined using the in vivo alkaline comet assay and the micronucleus test on the liver of the same individual mouse. Five genotoxic carcinogens, 1-nitropyrene (1-NP) (125 mg/kg), cyclophosphamide (CP) (50 mg/kg), methylmethan sulfonate (MMS) (80 mg/kg), mitomycin C (MMC) (2 mg/kg) and diethylnitrosamine (DEN) (50 mg/kg) were intraperitoneally dosed to each group consisting of 4 male ddY mice. The mice were subjected to PH 3, 8 or 24 hr after dosing of each carcinogen, and comet assay was performed using the removed liver. The regenerated hepatocyte was sampled five days after PH, and the incidence of micronucleus was measured. CP, MMS, MMC and DEN induced DNA damage at 8 and 24 hr after dosing, while 1-NP induced DNA damage only 8 hr after dosing. All five carcinogens induced micronuclei whenever PH was performed. In the case of CP, the peak of DNA damage was 24 hr after dosing and the timing of PH did not remarkably affect the incidence of micronuclei. The other 4 carcinogens showed peak DNA damage at 8 hr and the highest incidence of micronuclei when PH was operated 24 hr after dosing. In conclusion, we are the first to show the relation of induction between DNA damage and micronucleus in the liver from the same mouse, and tentatively showed the optimal timing of PH as 24 hr after dosing.     

Genotoxic effects of 4-methylimidazole on human peripheral lymphocytes in vitro

4-Methylimidazole (4-MEI), a heterocyclic organic chemical compound, is widely found in many foods and consumed by people worldwide. In this research, we aimed to investigate the cytotoxic and genotoxic effects of 4-MEI on human lymphocytes. For this purpose, human peripheral blood lymphocytes were treated with four concentrations of 4-MEI (300, 450, 600 and 750?μg/ml) for 24?h and 48?h periods and in vitro sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) tests were used. 4-MEI induced SCE in human peripheral lymphocytes at three highest concentrations (450, 600 and 750?μg/ml) in 48?h treatment period. CA and MN were induced in human peripheral lymphocytes at two highest concentrations of 4-MEI (600 and 750?μg/ml) in 24?h and 48?h treatment periods. The highest concentration of 4-MEI (750?μg/ml) induced MN formation more than the positive control MMC in 24?h treatment period. In addition, 4-MEI led to a decrease in MI at the highest concentration (750?μg/ml) in 24?h treatment period and at all concentrations in 48?h treatment period. 4-MEI reduced PI at all concentrations in 24?h treatment period and at all concentrations (expect the lowest) for 48?h treatment period. 4-MEI reduced nuclear division index (NDI) at 24 and 48?h treatment periods, even at the highest two concentrations, decreased more than the positive control MMC. Our results showed that 4-MEI pose a genotoxic and cytotoxic effects for human peripheral lymphocytes.     

Pre-bled-young-rats in genotoxicity testing: a model for peripheral blood micronucleus assay

Previously we have reported that prior bleeding increases the sensitivity of micronucleus (MN) assay in rats (Vikram et al., 2007 a). Rat peripheral blood micronucleus (PBMN) assay is generally not considered as reliable method for the assessment of clastogenic potential of test chemicals due to selective elimination of micronucleated cells from the circulation. The present study is aimed to evaluate the sensitivity of pre-bled-young-rat model in detecting genotoxins having different mechanism of action. In the present study, young male Sprague-Dawley (SD) rats (21-24 days old, weighing 60+/-5 g) and swiss mice (24-28 days old, weighing 15+/-2g) were used. Streptozotocin (STZ, 50mg/kg), Methotrexate (MTX, 10mg/kg), N-nitrosodiethylamine (DEN, 200mg/kg), Quercetin (QC, 50mg/kg) and Zidovudine (AZT, 400mg/kg) were used in the present experiment. Effect of prior bleeding time (0, 2, 6, 12 and 24h) on the kinetics of MN formation with STZ and AZT was studied and 36 h post chemical exposure was found to be the most suitable time point for sample collection if prior bleeding time was 0, 2 and 6h. Further, the impact of prior bleeding (2h) on the kinetics of MN formation in the bone marrow was evaluated with STZ and maximum MN frequency was observed after 24h. The area under curve (AUC) analysis proves that prior bleeding leads to significant increase in the incidence of micronucleated reticulocytes (RETs) in the peripheral blood as compared to respective non-bled controls. Out of five tested chemicals AZT and STZ induced significant increase in the MN frequency in non-bled animals while at the same dose MTX, AZT, QC and STZ induced significant increase in MN frequency in the pre-bled-young-rats employing PBMN assay as the end point. Positive results with MTX, AZT, QC, STZ and negative results with DEN demonstrate both the sensitivity and specificity of pre-bled-young-rat model in the screening of chemicals for genotoxicity using PBMN assay as the end point.     

The genotoxic and antigenotoxic effects of tannic acid in human lymphocytes

The genotoxicity of tannic acid (TA, tannin) were investigated using chromosome aberration (CA), sister chromatid exchange (SCE), and micronucleus (MN) test systems in human peripheral lymphocytes. Also, the antigenotoxicity of TA against known mutagen EMS was also examined. The lymphocytes were treated with 1.74?×?10(-5), 3.49?×?10(-5), and 6.98?×?10(-5) μM of TA for 24- and 48-hour treatment periods. For the antigenotoxicity of TA, the lymphocytes were treated with three different concentrations of TA and 2.71 μM of EMS. TA synergically induced the CA alone and with the mixture of EMS. However, TA did not induce the SCE alone, whereas TA and EMS as a mixture also synergically induced SCE. TA alone showed no clear effect on micronucleus formation, and it did not induce the MN when used with EMS as a mixture. In addition, TA showed a synergistic cytotoxic effect by decreasing the mitotic and nuclear division indices. The replication index was decreased at all concentrations for 48 hours of treatment time by TA and EMS as a mixture.     

彗星试验检测7种化合物对外周血淋巴细胞DNA的损伤

目的：检测过氧化氢（Ｈ２Ｏ２）、甲磺酸乙酯（ＥＭＳ）、丝裂霉素Ｃ（ＭＭＣ）、二甲基亚硝胺（ＤＭＮＡ）、苯并（ａ）芘（ＢａＰ）、２－氨基Ｗｕ（２－ＡＦ）和环磷酰胺（ＣＰ）诱发小鼠、大鼠及人外周血淋巴细胞ＤＮＡ单链断裂。方法：体外单细胞微量凝胶碱性电泳试验（慧星试验）。结果：除ＥＭＳ０．９７ｍｍｏｌ·Ｌ＾－１在小鼠淋巴细胞，ＭＭＣ３０μｍｏｌ·Ｌ＾－１在小鼠、人淋巴细胞中呈阴性外，其余均为阳性。最低可     

Suppressive effect of aspirin on chromosome aberration induced by mitomycin C in mice

Chromosome aberrations induced by mitomycin C (MMC) were suppressed by aspirin in a mouse micronucleus test with peripheral blood and bone marrow cells. Aspirin at doses of 0.5, 5, and 50 mg/kg was injected intraperitoneally or per administered orally 0.5, 6, or 24 h after administration of MMC and then peripheral blood and/or bone marrow cells were sampled 48 h after administration of MMC. The suppressive effect of aspirin was more pronounced in the aspirin-treated groups 24 h than 0.5 and 6 h after administration of MMC. In the aspirin-treated group at 24 h, the frequency of polychromatic erythrocytes with micronuclei was decreased by about 60-80% after intraperitoneal injection and by about 40-70% after oral administration. It is suggested that aspirin may directly act on MMC metabolites, but not on MMC itself.     

Genotoxicity of the isoflavones genistein, daidzein and equol in V79 cells

Hormonally active chemicals in the human diet, such as man-made estrogenic chemicals or plant-derived compounds (phytoestrogens), have become a matter of public concern. A significant part of human exposure to phytoestrogens is attributable to soy isoflavones. Besides their estrogenic properties, soy isoflavones also exert genotoxic actions. In this paper, the micronucleus (MN) assay in V79 cells was used to study chromosomal genotoxicity. Genistein caused a clear dose-related induction of MN within the range of 5-25 microM; MN rates were declining at higher genistein concentrations. This was probably due to cytotoxicity of genistein since reduced neutral red uptake and MTT formation with an IC(50) of about 75 microM occurred. Daidzein induced a comparatively shallow increase in the number of MN between 25 and 100 microM. In contrast, the daidzein metabolite equol caused an increase in the number of MN up to 25 microM with no further increase at higher concentrations. Additional staining with anti-kinetochore (CREST) antibodies served to determine if the micronuclei contain whole chromosomes or acentric fragments. Genistein induced mostly CREST(-) micronuclei, i.e. MN with chromosomal fragments, thus indicative of a clastogenic mode of action. MN induced by high concentrations of daidzein were partly CREST(+) and CREST(-), whilst equol induced mostly CREST(+) micronuclei indicative of an aneugenic action. These results point to a differential genotoxicity of phytoestrogens.     

The effects in mice of combined treatments to X-rays and antineoplastic drugs in the Comet assay

The Comet assay is a rapid, easy and reproducible method to detect genotoxic activity of chemical and physical agents in vitro and in vivo. In the present study the effects of exposure to irradiation or chemicals: cyclophosphamide (CP) and mitomycin C (MMC) or combined exposure to low doses of both agents (0.25 Gy+3.15 mg/kgbw CP and 0.25 Gy+0.25 mg/kgbw MMC) were examined for the induction of DNA damage in the Comet assay measured simultaneously in somatic (bone marrow lymphocytes) and haploid germ cells. The male mice were treated in vivo and sacrificed at 24 h after exposure. The percentage contents of DNA in the "comet tail" increased with increasing doses of X-rays and chemicals. After combined exposure to X-rays and CP and to X-rays and MMC weak increases of DNA damage in bone marrow lymphocytes and in germ cells were observed by comparison with the results obtained for each agent acting alone. There were slightly different responses in bone marrow lymphocytes and in germ cells, but effects were observed over a similar dose range.     

The genotoxic and antigenotoxic effects of Salvia fruticosa leaf extract in human blood lymphocytes

Abstract

The aim of this study was to investigate the genotoxic and antigenotoxic effects of Salvia fruticosa (Sf) leaf extract with the absence and presence of S9 mix using sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) formation test systems in human peripheral blood lymphocytes (HPBLs) that were treated with 1.5-, 3.0- and 6.0-µL/mL concentrations for 24- and 48-hour treatment periods. The cytotoxicity of Sf leaf extract was also investigated by calculating the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI). In the absence of S9 mix, Sf leaf extract alone increased SCE frequency at the 48-hour treatment period; however, it induced the CA and MN at all concentrations and at all treatment periods. Sf plus MMC (mitomycin C) synergically induced SCE and CA, except the highest concentration of Sf leaf extract and MMC on induction of SCE. In addition, Sf leaf extract induced the effect of MMC on MN frequency for 24 hours, but it significantly decreased the effect of MMC on MN frequency for the 48-hour treatment period. Sf leaf extract showed a cytotoxic effect by decreasing the MI; however, it did not decrease the PI and NDI. In the presence of S9 mix, Sf leaf extract did not increase the SCE, when compared to solvent control, whereas it reduced the effect of cyclophosphamide (Cyp). Sf leaf extract induced the CA and MN, but could not increase the effect of Cyp on CA and MN formation. Sf leaf extract had no cytotoxic effect; however, it induced the cytotoxicity of Cyp.     

Fresh water fish,Channa punctatus,as a model for pendimethalin genotoxicity testing: A new approach toward aquatic environmental contaminants

Pendimethalin (PND) is one of the common herbicides used worldwide. Fresh water fish, Channa punctatus, was exposed to PND in aquaria wherein its LC50 value was recorded to be 3.6 mg/L. Three sublethal (SL) concentrations, namely, 0.9, 1.8, and 2.7 mg/L were selected for the evaluation of genotoxicity and oxidative stress generated in the fish. In vivo comet assay was carried out in the blood, liver, and gill cells after exposing the fish to aforesaid SL concentrations of PND for 24, 48, 72, and 96 h. The results of the comet assay demonstrated the genotoxicity of PND in all the three tissues. Induction of oxidative stress in the gill cells was affirmed by the increased lipid peroxidation (LPO) and decreased levels of reduced glutathione, superoxide dismutase, and catalase. Frequencies of erythrocytic nuclear abnormalities (ENA) and micronuclei (MN) were also used to assess the genotoxic potential of PND on C. punctatus. MN frequency did not show any enhancement after PND exposure, but the frequency of ENA such as kidney‐shaped nuclei, segmented nuclei and lobed nuclei, showed a significant increase after 24–96 h. Thus, ENA seems to be a better biomarker than MN for PND induced genotoxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1520–1529, 2016.     

In vitro genotoxic and cytotoxic effects of some paraben esters on human peripheral lymphocytes

Parabens (PBs) are p-hydroxybenzoic acid ester compounds commonly employed as antimicrobial preservatives, mainly in food, cosmetic, and pharmaceutical products. The aim of the present study was to investigate the genotoxic and cytotoxic effects of some paraben esters (butyl paraben, propyl paraben, isobutyl paraben, and isopropyl paraben) on human peripheral lymphocytes, using in vitro sister chromatid exchange (SCE), chromosome aberration (CA), and cytokinesis-block micronucleus (CBMN) tests. Lymphocyte cultures were treated with four concentrations of PBs (100, 50, 25 and 10?µg/mL) for 24 and 48?h. Paraben esters significantly induced MN formations as compared to solvent control. Furthermore, butyl paraben and propyl paraben increased MN formations a concentration-dependent manner at 24 and 48?h. PBs increased the CA at 24 and 48?h. However, this increase was not meaningful for butyl paraben and isopropyl paraben at 48?h when compared with solvent control. Butyl, isobutyl, and isopropyl paraben significantly increased the SCE at 24 and 48?h. However, propyl paraben did not induce SCE meaningfully in both treatment periods. A significant decrease in the cytokinesis-block proliferation index and mitotic index was observed in cells exposed to all concentrations of PBs at 24 and 48?h. However, proliferation index was not affected at all concentrations of PBs after 24?h treatment, although it was decreased at the highest concentration of PBs at 48?h. It is concluded that all of the paraben esters used in this study have highly genotoxic and cytotoxic effects on human lymphocytes cells in vitro.     

基于L5178Y细胞的Pig-a基因突变试验方法学研究

目的:采用不同作用机制化合物研究基于L5178Y细胞体外Pig-a基因突变试验方法.方法:使用不同浓度范围的马兜铃酸Ⅰ ( aristolochic acid Ⅰ,AAI )、N-亚硝基二乙胺(N-nitrosodiethylamine,NDEA )、甲磺酸甲醋(methyl methanesulfonate,MMS ...     

The effect of extremely low frequency electromagnetic fields (ELF-EMF) on the frequency of micronuclei and sister chromatid exchange in human lymphocytes induced by benzo(a)pyrene

The interaction of extremely low frequency electromagnetic fields (ELF-EMF) on the frequency of micronuclei (MN) and sister chromatid exchange (SCE) induced by benzo(a)pyrene (BP) in human lymphocytes was examined. A 60 Hz ELF-EMF of 0.8 mT field strength was applied either alone or with the tumor initiator, BP for 24 h. The frequencies of MN and SCE induced by BP increased in a dose-dependent manner. The co-exposure of cells to BP and 0.8 mT ELF-EMF for 24 h, followed by BP exposure for 48 h led to significant increases in the frequencies of MN and SCE compared to BP treatment for 72 h alone (P<0.05), but no significant difference was observed between field exposed and sham exposed control cells. The obtained results suggest that low density ELF-EMF could act as an enhancer of the initiation process of BP rather than as an initiator of mutagenic effects in human lymphocytes.     

Investigation of genotoxic effects of paraben in cultured human lymphocytes

Paraben is a phenolic derivative of benzoic acid extensively used as preservatives in food, pharmaceutical, and cosmetic industries due to its antimicrobial characteristics. The objective of this study was to evaluate the in vitro genotoxic effects of paraben in human lymphocyte cultures. Cells were analyzed by cytokinesis-block micronucleus (CBMN), chromosome aberration (CA), sister chromatid exchange (SCE), and comet tests. For CBMN, CA, and SCE assays, the human lymphocytes were isolated from healthy donors and incubated with 500, 250, 100, and 50?µg/mL of paraben for 24 and 48?h, and for comet assay, cells were exposed to 1000, 750, 500, and 250?µg/mL of paraben for an hour. Results showed that numbers of MN and SCEs were not significant in the cells exposed to paraben when compared to the solvent control. However, 500 and 250?µg/mL of paraben induced the CA after 24?h. Also, we observed a significant decrease in the cytokinesis-block proliferation index in cells exposed 250–500?µg/mL paraben for 24?h, and 100, 250, and 500?µg/mL for 48?h. The mitotic index was also decreased at all concentrations and periods. However, the proliferation index was statistically decreased at all concentrations after 48?h treatments. Only the highest concentration of paraben caused DNA migration (mean tail length) in human lymphocytes analyzed by Comet assay. Taken together, results indicated that paraben had cytotoxic effects and caused genotoxicity by affecting directly chromosomes and DNA in human lymphocyte cells in vitro, and may have genotoxic potential for human.     

An in vitro micronucleus assay with size-classified micronucleus counting to discriminate aneugens from clastogens

In the in vitro micronucleus (MN) assay, genotoxic chemicals can be characterized as aneugens and clastogens by the presence and absence of kinetochore protein or centromere regions in the micronuclei, respectively. Aneugens preferentially induce kinetochore- or centromere-positive micronuclei which can be detected by the immunofluorescence staining method or the fluorescence in situ hybridization (FISH) method. Both methods are robust and reliable; however, these assays require a definite period of time and cost to obtain a result that suggests that the genotoxic chemicals cause aneuploidy. This is why these methods are not adequate to evaluate dozens of chemicals which are mixtures of aneugens and clastogens. To evaluate a batch of chemicals, a quicker and more convenient assay is desirable. In the present study, we examined whether the size-classified counting of MN is as effective as the FISH method to characterize aneuploidy in the in vitro MN assay using Chinese hamster lung (CHL) cell lines. As aneugens, 9 substances (colcemid, vincristine sulfate, paclitaxel, thiabendazole, diethylstilbestrol, griseofulvin, bisphenol A, fisetin and okadaic acid) were used; as clastogens 6 substances (methylmethane sulfonate, N-methyl-N′-nitro-N-nitroso-guanidine, etoposide, mitomycin C, hydroxyurea and actinomycin D) were used. The size-classified counting revealed that all the 9 aneugens increased both the frequency and proportion of large-size MN as compared with the vehicle control. Although N-methyl-N′-nitro-N-nitroso-guanidine, etoposide and mitomycin C increased the frequency, no increase was observed in the proportion. Meanwhile, with the FISH method, all the aneugens induced centromere-positive micronuclei but the clastogens did not. Based on these results, it is considered that the frequency of large-size MN in the in vitro MN assay is an alerting index for aneugenic effects and that its proportion is a simple and reliable index which is as effective as the FISH analysis for discrimination of aneugens from clastogens.     

Induction of micronuclei and nuclear lesions in Channa punctatus following exposure to carbosulfan,glyphosate and atrazine

Abstract

The genotoxic effects of commonly used agricultural pesticides viz., carbosulfan, glyphosate, and atrazine, were evaluated in Channa punctatus (Pisces, Perciformes) using micronucleus (MN) test and induction of nuclear lesions (NL). The 96?h LC₅₀ value were estimated by probit analysis as 0.27, 32.0 and 42.0?mg?L^?1, respectively, for carbosulfan, glyphosate, and atrazine using semi-static bioassays. Based on these values, three sublethal test concentrations of carbosulfan (0.07, 0.13, 0.20?mg?L^?1), glyphosate (8.1, 16.3, 24.4?mg?L^?1) and atrazine (10.6, 21.2, 31.8?mg?L^?1) corresponding to ¼, ½ and ¾ of the LC₅₀ of the pesticides respectively, were selected for exposure for 96?h. Peripheral blood samplings were taken at intervals of 24?h for assessment of MN and NL frequencies. Considerably higher genotoxic damage was induced by carbosulfan as compared to glyphosate and atrazine. There were significant effects (p?<?0.01) of concentrations in all the treated groups. The induction of MN and NL was highest at 96?h pesticide exposure at all test concentrations. The nuclear abnormalities recorded in this study, such as blebbed-, lobed-, notched- and bi-nuclei, other than micronuclei, are indicators of genotoxic damage.     

Genotoxic effects of a particular mixture of acetamiprid and α‐cypermethrin on chromosome aberration,sister chromatid exchange,and micronucleus formation in human peripheral blood lymphocytes

The genotoxic effects of a particular mixture of acetamiprid (Acm, neonicotinoid insecticide) and α‐cypermethrin (α‐cyp, pyrethroid insecticide) on human peripheral lymphocytes were examined in vitro by chromosomal aberrations (CAs), sister chromatid exchange (SCE), and micronucleus (MN) tests. The human peripheral lymphocytes were treated with 12.5 + 2.5, 15 + 5, 17.5 + 7.5, and 20 + 10 μg/mL of Acm+α‐cyp, respectively, for 24 and 48 h. The mixture of Acm+α‐cyp induced the CAs and SCEs at all concentrations and treatment times when compared with both the control and solvent control and these increases were concentration‐dependent in both treatment times. MN formation was significantly induced at 12.5 + 2.5, 15 + 5, 17.5 + 7.5, μg/mL of Acm+α‐cyp when compared with both controls although these increases were not concentration‐dependent. Binuclear cells could not be detected sufficiently in the highest concentration of the mixture (20 + 10 μg/mL) for both the 24‐ and 48‐h treatment times. Mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) significantly decreased because of the cytotoxic and cytostatic effects of the mixture, at all concentrations for two treatment periods. Significant decreases in MI and PI were concentration dependent at both treatment times. The decrease in NDI was also concentration‐dependent at 48‐h treatment period. In general, Acm+α‐cyp inhibited nuclear division more than positive control, mitomycin C (MMC) and showed a higher cytostatic effect than MMC. Furthermore, in this article, the results of combined effects of Acm+α‐cyp were compared with the results of single effects of Acm or α‐cyp (Kocaman and Topaktas, 2007 , 2009 , respectively). In conclusion, the particular mixture of Acm+α‐cyp synergistically induced the genotoxicity/cytotoxicity in human peripheral blood lymphocytes. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010.     

Evaluation of anti-oxidative,genotoxic and antigenotoxic potency of Codium tomentosum Stackhouse ethanolic extract in human lymphocytes in vitro

The genome is constantly exposed to agents, both exogenous and endogenous, that damage DNA. Consequently, it is very important that determination of this agents and the protective agents. In this work, we evaluated the antigenotoxic/antimutagenic activity of the crude ethanolic extracts of Codium tomentosum Stackhouse (Chlorophyceae) (CTE), collected from The Coast of South East Marmara Sea, in human lymphocytes culture in vitro against genotoxic/mutagenic agents MMC, EMS and H₂O₂ by using chromosome aberration (CA), sister chromatid exchange (SCE) and micronuclei (MN) assays as experimental endpoints. Also, in the present study, we determined total phenolic content and total antioxidant capacity (in soluble lipid and water). In addition, total protein, total carbohydrate, vitamins (A, C and E) and pigments (chlorophyll a, chlorophyll b and carotene) contents were also determined. Results of CA, SCE and MN tests show that CTEs have not shown genotoxic effect. In CTE plus MMC-, EMS- or H₂O₂- treated cultures, CA, SCE and MN frequency which induced by MMC, EMS or H₂O₂ has been decreased significantly (p < 0.05–0.001). This is the first report on genotoxicity/antigenotoxicity and anti-oxidative capacity of Codium tomentosum. Our results have clearly shown that CTE has strong anti-oxidative and antigenotoxic effect.     

In vivo and in vitro exposures for the evaluation of the genotoxic effects of lead on the Neotropical freshwater fish Prochilodus lineatus

In the present study, in vivo and in vitro exposures were used to assess the genotoxicity of lead (Pb) to the freshwater fish Prochilodus lineatus. The comet assay using blood, liver and gill cells, and the occurrence of micronuclei (MN) and other erythrocytic nuclear abnormalities (ENA) were used to assess the genotoxic potential of lead in vivo. Metallothionein content (MT) was measured in fish liver in order to evaluate the protection of fish against Pb toxicity. Fish erythrocytes were exposed to Pb in vitro (1, 3 and 6 h) and the number of viable cells, DNA integrity, using the comet assay, and lysosomal membrane stability, measured by the neutral red retention assay (NRRA) were analyzed. The results of the comet assay after in vivo toxicity tests (6, 24 and 96 h) showed that Pb was genotoxic for all the three tissues analyzed after 96 h exposure. A significant increase in liver MT content was observed after 6 and 24 h of Pb exposure. MN frequency did not increase after Pb exposures, but the frequency of the other ENA, such as kidney-shaped nuclei, segmented nuclei and lobed nuclei, showed a significant increase after 24 and 96 h, indicating that ENA is a better biomarker for Pb exposure than MN alone after short-term exposures. The results of the comet assay performed with erythrocytes in vitro exposed to lead confirmed its genotoxic effect and showed that DNA damage increased with increasing exposure time. Moreover, the NRRA clearly indicated that Pb induces a destabilization of the lysosomal membrane. These results demonstrate the potential genotoxicity and cytotoxicity of lead after acute exposures.     

The genotoxic and antigenotoxic potential of the methanolic root extract of Glycyrrhiza glabra L. on human peripheral blood lymphocytes

Glycyrrhiza glabra L. (licorice) is one of the most important medicinal plants, which is widely used throughout the world both in traditional and contemporary medical industries. This study was undertaken to investigate the potential genotoxic activity of G. glabra methanolic root extract, and its possible antigenotoxic properties against mitomycin C (MMC)-induced DNA damage in in vitro chromosome aberrations (CAs) and cytokinesis-block micronucleus (CBMN) assays in human peripheral blood lymphocytes (PBLs). Lymphocytes were treated with 25, 50, and 100?µg/ml G. glabra methanolic root extract alone as well as in combination with MMC (0.1?µg/ml) for 24 and 48?h treatment periods. It was found that there were no statistically significant differences between the negative control and the groups treated with all concentrations of G. glabra root extract of alone (p?>?0.05), demonstrating the absence of genotoxic effects at both 24 and 48?h treatment periods. Besides, the co-treatment of G. glabra methanolic root extract and MMC significantly decreased the percentage of structural CAs and MN formation when compared with the culture treated with MMC alone (p?G. glabra versus MMC. We can state that this extract acts as an antagonist and markedly decreased MMC-induced cytogenotoxicity. In conclusion, the present results demonstrate that in the tested experimental conditions, G. glabra methanolic root extract is not genotoxic in cultured human PBLs and has also antigenotoxic activity against MMC, which is widely used in chemotherapy against cancer.