Genotoxic effects induced by iprodione and tebuconazole in meristematic cells of Allium cepa: responses dependent on concentration and exposure time.

The present work explores the genotoxicity of the fungicides iprodione (IP) and tebuconazole (TB) using the Allium cepa assay as an in vivo biological model. Both short-term and long-term exposures were studied, revealing concentration- and time-dependent cytological and genotoxic effects. IP exhibited genotoxicity over a wider concentration range (5-50 µg/ml) and required 30 h of exposure, while TB showed genotoxicity at higher concentrations (10 and 30 µg/ml) within a 4-h exposure period. The study highlights the importance of assessing potential risks associated with fungicide exposure, including handling, disposal practices, and concerns regarding food residue. Moreover, the research underscores the genotoxic effects of IP and TB on plant cells and provides valuable insights into their concentration and time-response patterns.

Genotoxic effects induced for sub-cytotoxic concentrations of tebuconazole fungicide in HEp-2 cell line.

Tebuconazole (TB) is an active ingredient in formulations applied to control of fungal diseases in plants and classified as a possible human carcinogen. In the present study, the sub-cytotoxic concentrations of TB were evaluated for genotoxicity response in HEp-2 cell line. The HEp-2 cell line was exposed to 20, 40, and 50 µg/mL of TB in the Cytokinesis-block micronucleus (CBMN) assay and 40, 60, and 80 µg/mL in the comet assay (CA). Both negative centromere micronuclei (MNC-) as DNA damage were induced by the concentrations of TB assayed, suggesting a mostly clastogenic effect. The results obtained from the comet assay suggest that part of the endogenous DNA damage in the HEp-2 cell line could be repaired in presence of low TB concentrations by promoting the damage response. In conclusion, exposition to sub-cytotoxic concentrations of TB induces genotoxicity in the HEp-2 cell line. Therefore, the safety of their application should be evaluated.

Mitotic and chromosomal effects induced for biosynthesized nanoparticles from three mediators on Allium cepa root cells.

The genotoxicity of biogenic silver nanoparticles (AgNPs) obtained from three microbial mediators was assessed using the Allium cepa assay. Three clusters were differentiated for the highest frequency of end points of clastogenicity (stick-ends, fragments and bridges), end points of missegregation (C-metaphases and disorder anaphases), and lowest frequency of all the end points. In these clusters, the treatments were grouped respectively as I) positive control (GSF); II) silver nanoparticles form Aspergillus niger (AgNPs-An); and III) silver nanoparticles from both Cryptococcus laurentii (AgNPs-Cl) and Rhodotorula glutinis (AgNPs-Rg), Ag + , and negative control (NC). These results were in according to the principal component analisys (PCA) where treatments were associated to each component of the genotoxic effects. The statistical comparative analysis of the mitotic index (IM) and the abnormal mitosis frequency (AM) indicated that both GSF and AgNPsAn induce significant genotoxic effect. Low genotoxic effects were attributed to AgNPs-Cl and AgNPs-Rg, but mitogenic stimuli, similar to that obtained by the silver ions Ag + , were observed. Results suggested that different features of biogenic nanoparticles such as composition, size, and coating may be involved in the different cytological responses of the meristematic cells.

Dose-independent genotoxic response in A549 cell line exposed to fungicide Iprodione.

The fungicide Iprodione is widely applied in vegetables and raises concern for human health. The A549 human lung carcinoma cell line is a suitable model for assessing the toxicological effects of drugs. The goal of this work was to evaluate the genotoxicity and oxidative stress in the A549 cell line exposed to sublethal concentrations from 3 to 100 µg/mL Iprodione considering LC50 = 243.4 µg/mL Iprodione, as determined by the MTT assay. Generalized Linear Mixed Models (GLMM) were performed to determine the association between the responses NDI, MNim and MNib and the explanatory variables. Iprodione and solvent were relativized to the control whereas the concentration was included as numeric variable. ANOVA was used for the comparison of treatments. The coefficients of linear association between the explanatory variables and NDI, and the coefficients of logistic association between explanatory variables and MNim were not significant. However, these coefficients showed significant association with MNib only for Iprodione treatment but not for Iprodione concentration, indicating lack of dose-response relationship. Genotoxicity risk assessment indicated that the increase in Iprodione concentrations increased slightly the probability of belonging to the genotoxic category. ANOVA showed significant differences in MNib, and non-significant differences in NDI and MNim among treatments. The oxidative stress analysis performed at 3, 12, and 25 µg/mL Iprodione showed a significant and linear increase in SOD, and a significant and linear decrease in GSH and GST. The Dunnett test was significant for GSH at 12 and SOD at 25 µg/mL.

Genotoxicity evaluation using micronucleus test in Rattus norvegicus captured in urban ecosystems of Buenos Aires, Argentina.

The overall goal of the present study was to evaluate and compare the existence of genotoxic damage in Rattus norvegicus captured in sites with different levels of chemical mixtures along the Matanza-Riachuelo river basin (MRRB). For this, thirty-six wild rats (R. norvegicus) were captured from six different sites in the MRRB. Capture sites were characterized with concentrations of 20 parameters in surface water, including concentrations of metals and its soluble state and physicochemical parameters. To evaluate genotoxic damage in the rats, the bone marrow micronucleus test was performed. For this, the frequency of micronucleated polychromatic erythrocytes (MNPCE) was calculated based on the observation of 2000 polychromatic erythrocytes (PCE) per animal. Also, to detect possible cytotoxic effects, the PCE/TE (total erythrocytes) ratio in 1000 erythrocytes/animal was calculated. The frequency of MNPCE was positively associated with the highest concentration of chrome, lead, copper, biological oxygen demand, and chemical oxygen demand. Also, the decrease on PCE/TE ratio in bone marrow was related with increase of practically all metals and physicochemical parameters in surface water. The results of this study reveal that rats that live in the MRRB were exposed to concentrations of pollutants that can cause genotoxic damage, even though the concentrations of these pollutants are mostly below the safety standards. Therefore, this work highlights the importance of using methods that allow to integrate all environmental parameters in risk assessment, such as sentinel species.

Oxidative Response and Micronucleus Centromere Assay in HEp-2 Cells Exposed to Fungicide Iprodione.

The fungicide agents are a key component in the fruits and vegetables production. The Iprodione residues are one of the pesticide more frequently found in food products. The available data about the cytotoxicity of iprodione and its metabolites are scarce and do not allow characterization of its genotoxic potential and define the risk assessment.The human larynx epidermoid carcinoma cell line (HEp-2) has been shown to be sensitive to the toxic effects of xenobiotics of different origin and have been often used in citotoxicity and genotoxicity studies. The purpose of this paper is to evaluate the induction of genotoxicity and the role of oxidative stress in HEp-2cell line by exposure to the IP. The MTT test for viability resulted in CL50 85.86 (77.05-95.68) µg/mL of Iprodione. On the basis of this result, we proceeded to expose the cells to the sublethal concentrations (below the CL50) during 24 h to analyze the mitotic index and nuclear division index in order to determine the subcytotoxic concentrations of IP which the genotoxicity was evaluated. The subcytotoxic concentrations of 7, 17, and 25 µg/mL IP induced aneugenic effects as micronuclei centromere positive whereas 17 µg/mL was a threshold for centromere negative micronuclei induction in HEp-2 cells. The abnormal mitosis was induced for exposition of Hep-2 cells to the three concentrations. According to the result obtained, citotoxicity and genotoxicity oxidative stress studies were performed in 1.5, 7.0, and 25 µg/mL of IP. The results showed that the GSH intracellular content, the SOD activity and the levels of oxidative damage of the proteins were affected lead to redox imbalance. The decreased in the SOD activity and protein oxidation were in according to the result obtained to genotoxicity, suggesting that different biological targets could be affected.

Association between Genomic Instability and Evolutionary Chromosomal Rearrangements in Neotropical Primates.

During the last decades, the mammalian genome has been proposed to have regions prone to breakage and reorganization concentrated in certain chromosomal bands that seem to correspond to evolutionary breakpoints. These bands are likely to be involved in chromosome fragility or instability. In Primates, some biomarkers of genetic damage may be associated with various degrees of genomic instability. Here, we investigated the usefulness of Sister Chromatid Exchange as a biomarker of potential sites of frequent chromosome breakage and rearrangement in Alouatta caraya, Ateles chamek, Ateles paniscus, and Cebus cay. These Neotropical species have particular genomic and chromosomal features allowing the analysis of genomic instability for comparative purposes. We determined the frequency of spontaneous induction of Sister Chromatid Exchanges and assessed the relationship between these and structural rearrangements implicated in the evolution of the primates of interest. Overall, A. caraya and C. cay presented a low proportion of statistically significant unstable bands, suggesting fairly stable genomes and the existence of some kind of protection against endogenous damage. In contrast, Ateles showed a highly significant proportion of unstable bands; these were mainly found in the rearranged regions, which is consistent with the numerous genomic reorganizations that might have occurred during the evolution of this genus.

Induction of microtubule damage in Allium cepa meristematic cells by pharmaceutical formulations of thiabendazole and griseofulvin.

Microtubules (MT) are formed by the assembly of α- and ß-tubulins and MT-associated proteins. We characterized the effects of pharmaceutical formulations containing the microtubule disruptors thiabendazole (TBZ) and griseofulvin (GF) on the mitotic machinery of plant (A. cepa) meristematic cells. GF concentrations between 10 and 250 µg/ml were tested. GF induced mitotic index inhibition and genotoxic effects, including chromosome fragments, bridges, lagged chromosomes, C-metaphases, tripolar cell division, disorganized anaphases and nuclear abnormalities in interphase cells. Efects on the mitotic machinery were studied by direct immunofluorescence with ß-tubulin labeling and by DNA counterstaining with 4',6-diamidino-2-phenylindole (DAPI). Exposure of meristematic root cells to TBZ or GF, 100 µg/ml, caused microtubular damage which led to abnormal MT arrays. Our results suggest that GF induces abnormalities in spindle symmetry/polarity, while TBZ causes chromosome missegregation, polyploidy, and lack of cytokinesis.

Oxidative damage and antioxidant response of Allium cepa meristematic and elongation cells exposed to metronidazole.

The toxicity of metronidazole (MTZ) in meristematic and elongation zones of Allium cepa roots was analyzed for 30 h of exposition. Toxic effects were evaluated by lipid peroxidation (content of thiobarbituric-reactive substances [TBARS]), reduced glutathione (GSH) levels, ascorbate acid and dehydroascorbate acid content, and enzymatic activities of superoxide dismutase and catalase. The root zones showed differentiated susceptibility to MTZ. In the elongation zone, MTZ induced an increase of TBARS content and a significant rise in GSH levels, whereas in the meristematic zone, lipid peroxidation was not observed and all antioxidant defense parameters analyzed were significantly increased. These results indicate that MTZ exposure induced oxidative stress in A. cepa roots, and that the antioxidant defenses in the meristematic zone are more efficient compared with the elongation zone, which is probably related to higher oxidative metabolism of meristematic tissue.

Cytogenetic and microtubule array effects of the zineb-containing commercial fungicide formulation Azzurro(®) on meristematic root cells of Allium cepa L.

Zineb [ethylene bis(dithiocarbamate) zinc] is a widely employed foliar fungicide for agricultural and industrial applications. Allium cepa L. is a reliable model for the assessment of xenobiotic genotoxicity and cytotoxicity. We evaluated the effects of the zineb-containing commercial formulation Azzurro(®) (70% zineb) in cell cycle stages of the meristem root cells of A. cepa. The mitotic index (MI), chromosomal aberrations at anaphase/telophase (CAs), micronuclei (MN), and abnormalities in immunodetected microtubule structures, e.g., preprophasic band (PPB), mitotic spindle (MS), and phragmoplast (Phrag), were used as end-points. Azzurro(®) (1 and 10µg/ml) induced a significant increase in the frequency of CAs (P<0.05), and the higher concentration inhibited the MI (P<0.05) compared to control values. The frequency of MN did not differ from control values at any concentration. Treatment with 1µg/ml Azzurro(®) induced a significant increase in the frequency of abnormal PPB (P<0.01), MS (P<0.001), and Phrag (P<0.01) and, at 10µg/ml, enhancements in the frequencies of abnormal MS (P<0.05) and Phrag (P<0.05) were seen. A tubulin immunodetection assay showed that exposure to Azzurro(®) interferes with normal assembly of microtubule structures during mitosis.

Mutagenicidad quínica y evaluación de daño potencial mediante ensayos de corto plazo (ECT) / Chemical mutagenesis and evaluatial of potential damage by short term test (STT)

Los estudios del daño al DNA por agentes químicos se realizan en distintos niveles según el sistema experimental que se utilice. Es así que los ensayos propuestos para el monitoreo biológico se presentan en cuatro niveles diferentes: a) primer nivel: ensayos moleculares o en bacterias; b) segundo nivel: pruebas in vitro en células de cultivo; c) tercer nivel: análisis in vivo ; d) estudios en poblaciones expuestas. Se pueden evaluar tanto agentes químicos o físicos, como muestras de suelo, agua o aire (mezclas complejas). Se trabajó con ensayos de corto plazo (ECPs) para evaluar el daño genético potencial de diferentes agente químocos, productos naturales o contaminantes ambientales. En la actualidad, el interés particular consiste en caracterizar de modo exhaustivo diferentes derivados nitroimidazólicos como mebendazol (MBZ), tiabendazol (TBZ), metronidazol (MTZ) y ornidazol (ONZ), por su uso muy difundido como drogas antiparasitarias. El trabajo fue desarrollado con un amplio espectro de biomarcadores: aberraciones cromosónicas, cinética de proliferación celular, intercambio de cromátidas hermanas, retraso en anafase, micronúcleos, mutaciones de punto, recombinación somática, etcétera. Los estudios se han realizado en niveles crecientes de complejidad: nivel II (estudios in vitro en cultivos de célñulas de roedores y primates), nivel III (estudios in vivo en células de discos imaginales de insectos, células de médula ósea de roedores y linfocitos de primates) y nivel IV (estudios epidemiológicos en poblaciones humanas expuestas). Estos estudios que conllevan un enfoque multidisciplinario sobre un problema mediante el uso de distintos modelos animales son herramientas muy valiosas y pueden aplicarse al estudio de distintos contaminantes ambientales o a mezclas complejas.

Mutagenicidad quínica y evaluación de daño potencial mediante ensayos de corto plazo (ECT) / Chemical mutagenesis and evaluatial of potential damage by short term test (STT)

Los estudios del daño al DNA por agentes químicos se realizan en distintos niveles según el sistema experimental que se utilice. Es así que los ensayos propuestos para el monitoreo biológico se presentan en cuatro niveles diferentes: a) primer nivel: ensayos moleculares o en bacterias; b) segundo nivel: pruebas in vitro en células de cultivo; c) tercer nivel: análisis in vivo ; d) estudios en poblaciones expuestas. Se pueden evaluar tanto agentes químicos o físicos, como muestras de suelo, agua o aire (mezclas complejas). Se trabajó con ensayos de corto plazo (ECPs) para evaluar el daño genético potencial de diferentes agente químocos, productos naturales o contaminantes ambientales. En la actualidad, el interés particular consiste en caracterizar de modo exhaustivo diferentes derivados nitroimidazólicos como mebendazol (MBZ), tiabendazol (TBZ), metronidazol (MTZ) y ornidazol (ONZ), por su uso muy difundido como drogas antiparasitarias. El trabajo fue desarrollado con un amplio espectro de biomarcadores: aberraciones cromosónicas, cinética de proliferación celular, intercambio de cromátidas hermanas, retraso en anafase, micronúcleos, mutaciones de punto, recombinación somática, etcétera. Los estudios se han realizado en niveles crecientes de complejidad: nivel II (estudios in vitro en cultivos de célñulas de roedores y primates), nivel III (estudios in vivo en células de discos imaginales de insectos, células de médula ósea de roedores y linfocitos de primates) y nivel IV (estudios epidemiológicos en poblaciones humanas expuestas). Estos estudios que conllevan un enfoque multidisciplinario sobre un problema mediante el uso de distintos modelos animales son herramientas muy valiosas y pueden aplicarse al estudio de distintos contaminantes ambientales o a mezclas complejas. (AU)