The effects of organophosphorus insecticides and heavy metals on DNA damage and programmed cell death in two plant models

The ubiquity of pollutants, such as agrochemicals and heavy metals, constitute a serious risk to human health. To evaluate the induction of DNA damage and programmed cell death (PCD), root cells of Allium cepa and Vicia faba were treated with two organophosphate insecticides (OI), fenthion and malathion, and with two heavy metal (HM) salts, nickel nitrate and potassium dichromate. An alkaline variant of the comet assay was performed to identify DNA breaks; the results showed comets in a dose-dependent manner, while higher concentrations induced clouds following exposure to OIs and HMs. Similarly, treatments with higher concentrations of OIs and HMs were analyzed by immunocytochemistry, and several structural characteristics of PCD were observed, including chromatin condensation, cytoplasmic vacuolization, nuclear shrinkage, condensation of the protoplast away from the cell wall, and nuclei fragmentation with apoptotic-like corpse formation. Abiotic stress also caused other features associated with PCD, such as an increase of active caspase-3-like protein, changes in the location of cytochrome C (Cyt C) toward the cytoplasm, and decreases in extracellular signal-regulated protein kinase (ERK) expression. Genotoxicity results setting out an oxidative via of DNA damage and evidence the role of the high affinity of HM and OI by DNA molecule as underlying cause of genotoxic effect. The PCD features observed in root cells of A. cepa and V. faba suggest that PCD takes place through a process that involves ERK inactivation, culminating in Cyt C release and caspase-3-like activation. The sensitivity of both plant models to abiotic stress was clearly demonstrated, validating their role as good biosensors of DNA breakage and PCD induced by environmental stressors.

Gibberellins application timing modulates growth, physiology, and quality characteristics of two onion (Allium cepa L.) cultivars

Lack of scientific literature exists regarding the effects of gibberellic acid (GA₃) application timings on various phenological and physiological aspects of seed crop of locally available onion cultivars. Therefore, current study was planned in Vegetable Research Area, University of Agriculture, Faisalabad to optimize the growth stage for GA₃ application on seed production in two local onion cultivars (Phulkara and Dark Red) during 2013 and 2014. Application timings of gibberellins at 100 mg/L of H₂O were as (G₁) control (no spray), (G₂) foliar application at 2-3 leaf stage, (G₃) foliar application at 6-7 leaf stage, and (G₄) foliar application at the time of flowering. Data on average of both years showed that tallest plants (66.15 cm) and maximum number of leaves per plant (84.56) were noted in cv. Phulkara when GA₃ was applied at 2-3 leaf stage. Minimum number of days to initiate flowering (47.92) and maximum number of umbels per plant (15.45) were noted with GA₃ application at 6-7 leaf stage in Phulkara and Dark Red, respectively. The highest seed yield per umbel (2.94 g) was recorded in cv. Dark Red when GA₃ sprayed at 6-7 leaf stage, while GA₃ application at the time of flowering in the cv. Phulkara produced seeds with highest seedling vigor index (586.79). Overall, it appears that seed yield and quality characters were promoted by the application of GA₃ at different growth stages and could be valuable for seed production of onion.

One-pot synthesis of anilides, herbicidal activity and molecular docking study

BACKGROUND

In the context of the demand for more efficient herbicides, the aim of the present work was to synthesize anilides via simple methods, and evaluate their herbicidal activities through seed germination assays. In silico studies were carried out to identify the enzyme target sites in plants for the most active anilides.

RESULTS

A total of 18 anilides were prepared via one-pot reaction in yields that varied from 36 to 98% through reactions of anilines with sorbic chloride and hexanoic anhydride. According to seed germination assays in three dicotyledonous and one monocotyledonous plant species, the most active anilides showed root and shoot growth inhibition superior to that of Dual (S-metolachlor). In silico studies indicated that histone deacetylase was the probable enzyme target site in plants for these substances. The affinities of the most active anilides for the binding sites of this enzyme were equal to or higher than those calculated for its inhibitors.

CONCLUSION

Anilides 4d, 4e, 4 g, and 4 h are promising candidates for the development of novel herbicides. According to in silico studies, they inhibit histone deacetylase in plants, which can be exploited for the development of new weed control methods. © 2018 Society of Chemical Industry.

Assessment of surface water using Allium cepa test and histological analysis in Rhamdia quelen

This study aimed to assess the cytotoxic, genotoxic, and mutagenic potentials of water samples collected in the Alegre River Basin, located in a predominantly rural area with no sewage treatment facilities in the Espírito Santo State, Brazil, using Allium cepa test. Also, gills and liver of Rhamdia quelen, a common fish species of the region, were histologically analyzed. A semi-quantitative analysis was performed and a histopathological alterations index (HAI) was determined. Our findings indicated that the waters of this river basin were cytotoxic (mitotic index reduction) and/or genotoxic (chromosomal abnormalities induction). Mutagenicity (micronuclei induction) was not observed for any water sample. The values for HAI showed that the waters caused moderate histological alterations in R. quelen. Liver was more sensitive than gills. It is necessary to implement a sewage treatment system and raise awareness on inappropriate management and disposal of agrochemicals in order to allow the recovery of Alegre River.

Cytotoxic Assessment of Chromium and Arsenic Using Chromosomal Behavior of Root Meristem in Allium cepa L

A study was performed for phyto-genotoxic assay of chromium (Cr) and arsenic (As) through Allium cepa. Various concentrations (0, 1, 3, 6 and 12 mg L^-1) of Cr and As for 48 and 168 h time points exposed to A. cepa. The phytotoxic effects of metal(loid) were evident through inhibited root length and root protein. Metal(loid) toxicity also lead to genotoxic effects, which included depression of mitotic index and increased frequency of chromosomes aberrations like break, fragments, c-metaphase, multipolar arrangements etc. Genotoxic endpoint as progressive frequency of micronuclei in interphase of root meristem cells in treated plants was also observed. This genotoxic endpoint revealed carcinogenic nature of both aforementioned metal(loid). Along with inhibition in root length and protein content, depression in mitotic index as well as stimulation of various abnormality in mitotic cell division indicated that both metal(loid) are hazardous in nature and causing harmful effect on the environment.

X-ray fluorescence spectrometry characteristics of oily waste water from steel processing and an evaluation of its impact on the environment

Metal-cutting fluids, one of the most consumed materials in the metallurgy industry, turn into oily wastewater after being used in the metalworking processes. The amount of cutting fluids used can reach up to millions of tons. And these invaluable fluids are difficult to distil and expensive, and impossible to store. Even after it is disposed and recaptured, the end product has no commercial value. In this study, the effect of this mixture was examined on the ecosystem using the Allium cepa test system in which onion root tips were treated with three different concentrations of waste-cutting fluid, based on a 24- and 48-h cell cycle. The oily wastewater exhibited a mechanism which triggered the chromosomal and nuclear abnormalities in the onion root-tip meristem and reduced the mitotic index. Common abnormalities observed in the experimental groups based on the water concentration were chromosome stickiness, c-mitosis, and micronuclei formation. In the experimental group with the lowest water concentration, budding nuclei were observed at a different level than all of the other experimental groups. The x-ray fluorescence analysis showed that the concentrations of elements, such as silicon, calcium, iron, and zinc, were higher in the oily wastewater than those in the unused cutting oil.

Short-term assessment of cadmium toxicity and uptake from different types of Cd-based Quantum Dots in the model plant Allium cepa L

We report on the toxicity and bioaccumulation of three different types of Cd-based quantum dots (QDs), dispersed in aqueous medium, for a model plant Allium cepa L. It is believed that encapsulation of nanoparticles should reduce their toxicity and increase their stability in different environments; in this work we studied how QD encapsulation affects their phytotoxicity. Core, core/shell, and core/shell/shell QDs (CdTe, CdTe/ZnS, and CdTe/CdS/ZnS QDs capped by 2-mercaptopropionic acid) were tested and CdCl₂ was used as a positive control. After 24-h and 72-h exposure, total Cd content (M_Cd) and bioaccumulation factors (BAFs) were determined in all parts of A. cepa plants (roots, bulb, shoot), and the total length of the root system was monitored as a toxicity end-point. Measurements of total Cd content versus free Cd²⁺ content (with Differential Pulse Voltammetry, DPV) in exposure media showed differences in chemical stability of the three QD types. Correspondingly, selected QDs showed different toxicity for A. cepa and different Cd bioaccumulation patterns. CdTe QDs were the most toxic; their effect was similar to CdCl₂ due to the release of free Cd²⁺, which was confirmed by the DPV measurements. Plants exposed to CdTe QDs also bioaccumulated the most Cd among all QD exposure groups. CdTe/ZnS QDs showed no toxicity and very low bioaccumulation of Cd in A. cepa; the main source of measured Cd in the plants were QDs adsorbed on their roots, which was confirmed by fluorescence microscopy. On the contrary, CdTe/CdS/ZnS QD toxicity and bioaccumulation patterns were similar to those of CdTe QDs and pointed to unstable CdS/ZnS shells.

Ecotoxicity tests with Allium cepa to determine the efficiency of rice husk ash in the treatment of groundwater contaminated with benzene, toluene, ethylbenzene, and xylene

The validation of adsorption treatment based on toxicity assays aims to assess the actual environmental impact caused by effluents after treatment. This study describes the use of rice husk ash as adsorbent and evaluates the efficiency of adsorption treatment to remediate groundwater contaminated with benzene, toluene, ethylbenzene, and xylene (BTEX). The synthetic effluent was prepared with standard benzene, toluene, ethylbenzene, and xylene solutions. Adsorption was assessed at treatment times 0, 60, 120, and 240 min. Compounds were quantified by gas chromatography with flame ionization detector. The treatment was validated based on ecotoxicity assays using Allium cepa as indicator organism. For the treatment times stipulated, samples containing 25, 50, and 100% of BTEX were used. The dilutions were carried out with drinking water according to Fiskesjö (1985). The relative growth index (RGI), root inhibition index (Ii), and germination index (GI) confirmed the efficiency of the treatment approach tested. The best adsorption time for an initial BTEX concentration of 3.378 mg/L was 60 min. Critical level (EC50) and critical concentration that induced phytotoxic effect on A. cepa germination was observed only for the undiluted effluent.

Allium cepa root tip assay in assessment of toxicity of magnesium oxide nanoparticles and microparticles

Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide (MgO) particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano- and microparticles (NPs and MPs) at a range of exposure concentrations (12.5, 25, 50, and 100μg/mL). The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index (MI) when compared to control cells and the effect was more significant for NPs than MPs (at p<0.05). Comet analysis revealed that the Deoxyribonucleic acid (DNA) damage in terms of percent tail DNA ranged from 6.8-30.1 over 12.5-100μg/mL concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.

Biodegradation of Azure-B dye by Serratia liquefaciens and its validation by phytotoxicity, genotoxicity and cytotoxicity studies

The azo dyes in textile industry are a major source of environmental pollution and cause serious threat to aquatic flora and fauna. The present study aims to evaluate the potential of previously isolated lignin peroxidase (LiP) enzyme producing Serratia liquefaciens in degradation of Azure-B (AB) dye. S. liquefaciens showed rapid decolourisation of AB dye (100 mg L^-1) in mineral salt medium (MSM) supplemented with 0.2% glucose and yeast extract, and more than 90% dye decolourisation was observed at 48 h when incubated at 30 °C. Decolourisation conditions were optimized by Response Surface Methodology (RSM) using Box-Behnken Designs (BBD). The dye degradation was further confirmed by ATR-FTIR and GC-MS analysis. Toxicological studies of untreated (UT) and bacterial treated (BT) AB dye solutions were studied by using phytotoxicity, genotoxicity and cytotoxicity endpoints. Phytotoxicity assay using Vigna radiata indicated that bacterial treatment led to detoxification of AB dye. Genotoxicity assay with Allium cepa showed that pure AB dye solutions significantly reduced mitotic index (MI) and induced various chromosomal abnormalities (CAs) like c-mitosis, stickiness, chromosome break, anaphase bridges, vagrant chromosomes and binucleated and micronucleated cell in the root tip cells, whereas, bacterial treated solutions induced relatively less genotoxicity in nature. Improved cell survivability (%) was also noted in kidney cell line (NRK-52E) after S. liquefaciens treated dye solutions than the pure dye solutions. The findings suggest that S. liquefaciens could be a potential bacterium for azo dye degradation, as it is effective in lowering of toxic effects of AB dye.

Cyto-genotoxic consequences of carbendazim treatment monitored by cytogenetical analysis using Allium root tip bioassay

Environmental pollution is one of the major problems of these days. One of the reasons of environmental pollution is the indiscriminate use of agrochemicals in agriculture. Fungicides are being extensively used in agriculture for enhancing crop yield and growth by controlling fungal growth. Fungicide carbendazim is widely applied to soil and seeds of vegetable/cereal crops in India and is effective against a very broad spectrum of fungi. The present study was designed to monitor the cyto-genotoxic effects of carbendazim directly in treated soils by cytogenetical analysis using Allium cepa root tip bioassay. In a pot experiment, fungicide carbendazim was added to soil at the rates of 2.5, 5, 7.5, and 10 mg kg^-1 soil and uniform size onion bulb was planted in each pot, and three replicates were maintained for each dose at 1, 7, 15, 30, and 45 days after application and roots from onion bulbs were fixed for cytogenetical analysis. Findings indicate that carbendazim treatment leads to a significant dose and duration-dependent decrease in percent mitotic index with related increase in mitotic inhibition. Statistical analysis showed a significant effect of carbendazim doses and duration of treatment on the percentage relative abnormality rate of A. cepa. Phase indices of our study showed high numbers of cells in prophase as compared to other phases at some doses of treatment. The different types of chromosomal abnormalities observed in our study serve as indicators of genotoxicity of carbendazim and we report for the first time the effect of its application directly in soil using a plant test system.

Monitoring of morphotoxic, cytotoxic and genotoxic potential of mancozeb using Allium assay

The present experiment was designed to monitor the morphotoxic, cytotoxic and genotoxic potential of Mancozeb (fungicide) in non-target plants using bulbs of Allium cepa. Mancozeb is classified as a contact fungicide and is registered for use on a variety of crop plants. In the present monitoring, Allium cepa bulbs were exposed to different concentrations of mancozeb viz., 10, 30, 50, 70, 90, 110, 130 and 150 ppm for 24 and 48 h. The potential morphotoxic and cytotoxic effects of mancozeb were examined by determining the average root number, average root length, mitotic index, relative abnormality rate (%) and frequency of abnormalities (%). A progressive significant concentration and time dependent inhibition of the average root number, average root length indicated the morphotoxic nature. The cytotoxic effect was significantly increased for 48 h treatment as compared to 24 h treatment time, by reducing the mitotic index of meristematic cells. The results indicated an indirect genotoxic effect by inducing different types of chromosomal abnormalities, likely sticky, disoriented and fragmented chromosomes. Thus indicating that the investigated fungicide have genotoxic potential due to abnormal DNA condensation and chromosome coiling by spindle inactivation. The observations of cyto and genotoxic effects suggest that the fungicide mancozeb is clastogenic agent. Thus the different concentrations used in the field could be harmful for the end-receptors of food-chain and needs constant monitoring and management for the better development of crop plants.

Phytochemical screening and antibacterial potential of Artemisia absinthium L., Swertia chirayita and Sphaeranthus indicus

Utilization of herbs for medicinal purpose started in the early history of mankind several thousand years ago. In this study, some plants that are used for lowering cholesterol level in local areas of Pakistan, such as Artemisia absinthium L., Swertia chirayita and Sphaeranthus indicus were screened for their phytochemical and antibacterial properties. For this purpose, these plants were extracted in different solvents i.e. ethanol, hexane and ethyl acetate. Phytochemcial analysis unveiled the existence of different bioactive compounds in these extracts. Presence of sugars was further confirmed by performing TLC. Antibacterial activity was determined against indicated bacterial strains, among all extracts Gul-e-mundi had maximum inhibition zone (23mm). DPPH free radical assay revealed the significant antioxidative potential of all the extracts where Gul-e-mundi showed maximum potential i.e., 83%. Plant extracts were also showing anti-proliferative activity on root tips of Allium cepa and Gul-e-mundi was observed to have maximum antimitotic activity i.e. 5%. GC-MS analysis revealed that oleic acid and linoleic acid were the compounds responsible for imparting antibacterial potential to Gul-e-mundi. In conclusion, among all the tested extracts Gul-e-mundi had maximum antibacterial, antioxidative and antimitotic potential. For future studies, phytochemcials responsible for these activities can be isolated and modified for pharmacological purpose.

Genotoxicity assessment of raw and treated water samples using Allium cepa assay: evidence from Perak River, Malaysia

Allium cepa assay was carried out in this study to evaluate genotoxic effects of raw and treated water samples from Perak River in Perak state, Malaysia. Samples were collected from three surface water treatment plants along the river, namely WTPP, WTPS, and WTPK. Initially, triplicates of equal size Allium cepa (onions) bulbs, 25-30 mm in diameter and average weight of 20 g, were set up in distilled water for 24 h at 20 ± 2 °C and protected from direct sunlight, to let the roots to grow. After germination of roots (0.5-1.0 cm in length), bulbs were transferred to collected water samples each for a 96-h period of exposure. The root physical deformations were observed. Genotoxicity quantification was based on mitotic index and genotoxicity level. Statistical analysis using cross-correlation function for replicates from treated water showed that root length has inverse correlation with mitotic indices (r = - 0.969) and frequencies of cell aberrations (r = - 0.976) at lag 1. Mitotic indices and cell aberrations of replicates from raw water have shown positive correlation at lag 1 (r = 0.946). Genotoxicity levels obtained were 23.4 ± 1.98 (WTPP), 26.68 ± 0.34 (WTPS), and 30.4 ± 1.13 (WTPK) for treated water and 17.8 ± 0.18 (WTPP), 37.15 ± 0.17 (WTPS), and 47.2 ± 0.48 (WTPK) for raw water. The observed cell aberrations were adherence, chromosome delay, C-metaphase, chromosome loss, chromosome bridge, chromosome breaks, binucleated cell, mini cell, and lobulated nuclei. The morphogenetic deformations obtained were likely due to genotoxic substances presence in collected water samples. Thus, water treatment in Malaysia does not remove genotoxic compounds.

Direct and Indirect Anthropogenic Contamination in Water Sources: Evaluation of Chromosomal Stability and Cytotoxicity Using the Allium cepa Test

Increasing industrialization and urbanization has deteriorated water quality around the world. Nowadays, evaluation of the effects of chemical compounds using bioassays is a critical step in the hazard identification assessment. Thus, this work aimed to determine the genetic damage caused by different types of anthropogenic contamination in a river´s water in Brazil. Two points (P1 and P2) and two periods (referred as direct and indirect anthropogenic contamination) were evaluated in Allium cepa roots. MI was increased (p < 0.05) in both points in the indirect anthropogenic contamination and decreased in the indirect anthropogenic contamination periods. Moreover, parameters as DNA instability (CA and MN) were observed in both periods indicating substances in the water with mutagenic, genotoxic, and cytotoxic potential. Interestingly, a 20-fold increase in CA frequencies were observed in P1 and P2 in the second collection period (direct anthropogenic contamination) (p < 0.05). In conclusion, our data indicated that anthropogenic activities in the area contributed to contaminate this water source. Moreover, direct anthropogenic contamination maximized the damage, posing a possible hazard to population health.

Ecotoxicological and microbiological assessment of sewage sludge associated with sugarcane bagasse

Sewage sludge (SS) obtained after sewage treatment process may contain several toxic substances. Bioremediation can decrease the toxicity of the sludge, mainly when it is associated with stimulant agents, such as sugarcane bagasse (B). Samples of pure SS (SSP); SS+B; SS+Soil; and SS+B+Soil were bioremediated for 1, 3, and 6 months (T1, T2, and T3, respectively). After each period, the cytotoxic, genotoxic, and mutagenic potentials of the solid samples and their respective aqueous extracts (aqueous eluate and percolate water) were evaluated by the Allium cepa test. A microbiological analysis of the samples was also performed after each period tested. All solid samples of SS+B (in T1, T2, and T3) and the solid sample of SSP (treatment T3) showed a significant decrease of cell division (cytotoxic effects). The aqueous eluate extracts of SS+B (T1 and T3) and SSP (T2 and T3) induced cytotoxic effect. The solid sample of SS+B (T2 and T3) and aqueous extracts of SSP (T1) were genotoxic, indicating a harmful effect of SS on A. cepa, even after 6 months of bioremediation. There was an alternation in the microbial community both in diversity and in abundance, with the predominance of nonfermenting gram-negative bacilli. The tested bioremediation periods were not sufficient for the complete detoxification of SS, and the use of B did not seem to contribute to the degradation of the pollutants to inert compounds. These data emphasize that a specific relationship should exist between the sludge characteristic and the biostimulating agent used to promote a more efficient bioremediation. These results suggest the necessity to study longer periods of biodegradation and the use of other decomposing agents for greater safety and sustainability for the agricultural use of this residue.

OsMYB45 plays an important role in rice resistance to cadmium stress

Cadmium (Cd) is one of the most toxic heavy metal elements in nature, and it causes serious damage to plant cells. Here, we report that a transcription factor OsMYB45 is involved in Cd stress response in rice. OsMYB45 is highly expressed in rice leaves, husks, stamens, pistils, and lateral roots, and its expression is induced by Cd stress. OsMYB45 fused to green fluorescent protein localized to the cell nucleus in onion epidermal cells. Mutation of OsMYB45 resulted in hypersensitivity to Cd treatment, and the concentration of H₂O₂ in the leaves of mutant nearly doubled, while catalase (CAT) activity was halved compared with the wild-type. Moreover, gene expression analysis indicated that OsCATA and OsCATC expression is significantly lower in the mutant than in the wild-type. In addition, overexpression of OsMYB45 in the mutant complemented the mutant phenotype. Taken together, OsMYB45 plays an important role in tolerance to Cd stress in rice.

The influence of heavy metals on toxicogenetic damage in a Brazilian tropical river

Anthropogenic activities in tropical rivers favor the eutrophication process, which causes increased concentration of heavy metals. The presence and bioaccumulation of metals are directly related to the presence of genotoxic damage in aquatic organisms. Thus, we evaluated the presence of heavy metals (Fe, Zn, Cr, Cu and Al) and performed toxicogenetic tests in surface (S) and bottom (B) of water samples of the Poti river (Piaui/Brazil). Cytotoxicity and genotoxicity tests were performed in Allium cepa, and micronucleus (MN) and comet assay were performed in Oreochromis niloticus. The chemical analysis showed concentrations above the limit for Cu, Cr, Fe and Al according to Brazilian laws, characterizing anthropogenic disturbance in this aquatic environment. Toxicogenetic analysis presented significant cytotoxic, mutagenic and genotoxic effects in different exposure times and water layers (S and B), especially alterations in mitotic spindle defects, MN formations, nuclear bud and DNA strand breaks. Correlations between Fe and cytotoxicity, and Al and mutagenicity were statistically significant and point out to the participation of heavy metals in genotoxic damage. Therefore, Poti river water samples presented toxicogenetic effects on all bioindicators analyzed, which are most likely related to heavy metals pollution.

Effects of long exposure to spent potliner on seeds, root tips, and meristematic cells of Allium cepa L

Spent potliner (SPL) is a solid waste generated in the aluminum mining and processing industry. It is sometimes dumped into the environment and leach in contact with water, thereupon affecting living beings, which are likely to be exposed to the waste for long periods. Considering this, we aimed to evaluate the effects of extended exposure to SPL through bioassays using Allium cepa as plant model system. Seeds of A. cepa were either directly exposed to SPL (continuous exposure) or first germinated in water and then exposed to SPL (discontinuous exposure). The germination rate was determined from 24 to 192 h of exposure. The maximum effects of SPL on germination were observed after 96 h in both exposure approaches. For the parameter root elongation, the discontinuous treatment was more efficient in demonstrating differences among the applied SPL concentrations (60% of reduction). Microscopic analysis was carried out in root tip cells discontinuously exposed to SPL for 96 h. A mitodepressive effect was observed (above 50%), as well as increased rate of chromosome abnormalities (up to 100-fold) and induction of cell death. The consequences of exposure to SPL for longer periods are discussed.

Performance of an integrated system combining microalgae and vertical flow constructed wetlands for urban wastewater treatment

The present study investigated the performance of an integrated system, combining the sequential use of microalgae (MA) and vertical flow constructed wetland (VFCW) for the treatment of wastewaters produced at a university campus. Ecotoxicity and phytotoxicity assays were performed using respectively Daphnia magna and Lactuca sativa, whereas the genotoxicity of the wastewaters was assessed by using D. magna and Allium cepa. The results revealed that the major environmental impacts of the studied wastewaters are associated with the high eutrophication potential, due to high N-NH3 (68.8 ± 25.7 mg L-1), total P (7.71 ± 2.5 mg L-1), and BOD5 (526.4 ± 177 mg L-1) values, pathogenic load, and genototoxicity (p < 0.0001). The results also showed that the integrated system (MA + VFCW) was not able to satisfactory reduce the total p values (only 4%). Nevertheless, the MA + VFCW system achieved very promising results for the nitrogen removal, with emphasis on N-NH3 removal (100%) and the highest BOD5 removal (57%). Neither the raw wastewaters nor the treated wastewaters were phytotoxic. The integrated system completely eliminated the ecotoxicity (100%) and genotoxicity (n.s.) of the raw wastewater and showed decontamination potential. Thus, the integrated system emerges as an innovative environmental technology and, with minor adjustments, might be efficiently used in large scale and eventually replace conventional wastewater treatment systems.

Evaluation of toxic and genotoxic potential of a wet gas scrubber effluent obtained from wooden-based biomass furnaces: A case study in the red ceramic industry in southern Brazil

Red ceramic industry in southern Brazil commonly uses wood biomass as furnace fuel generating great amounts of gas emissions and ash. To avoid their impact on atmospheric environment, wet scrubbing is currently being applied in several plants. However, the water leachate formed could be potentially toxic and not managed as a common water-based effluent, since the resulting wastewater could carry many toxic compounds derived from wood pyrolysis. There is a lack of studies regarding this kind of effluent obtained specifically and strictly from wooden-based biomass furnaces. Therefore, we conducted an evaluation of toxic and genotoxic potentials of this particular type of wet gas scrubber effluent. Physical-chemical analysis showed high contents of several contaminants, including phenols, sulphates and ammoniacal nitrogen, as well as the total and suspended solids. The effluent cause significant toxicity towards microcrustacean Artemia sp. (LC50 = 34.4%) and Daphnia magna (Toxicity Factor = 6 on average) and to higher plants (Lactuca sativa L. and Allium cepa L.) with acute and sub-acute effects in several parameters. Besides, using plasmid DNA, significant damage was observed in concentrations 12.5% and higher. In cellular DNA, concentrations starting from 12.5% and 6.25% showed significant increase in Damage Index (DI) and Damage Frequency (DF), respectively. The results altogether suggest that the effluent components, such phenols, produced by wood combustion can be volatilized, water scrubbed, resulting in a toxic and genotoxic effluent which could contaminate the environment.

Toxicity of two effluents from agricultural activity: Comparing the genotoxicity of sugar cane and orange vinasse

Vinasse, produced by several countries as a by-product of agricultural activity, has different alternatives for its reuse, mainly fertirrigation. Several monocultures, such as sugar cane and orange crops, produce this effluent. Sugar cane vinasse is already widely used in fertirrigation and orange vinasse has potential for this intention. However, its use as a fertilizer has caused great concern. Thus, ecotoxicological evaluation is extremely important in order to assess the possible effects on the environment. Therefore, the aim of this study was to evaluate the potential toxicity of vinasse of two different crops: sugar cane and orange. For this purpose, bioassays with Allium cepa as a test organism were performed with two vinasse dilutions (2.5% and 5%) to detect chromosomal aberrations and micronucleus induction. The results showed that both types of vinasse are able to induce chromosomal aberrations in meristematic cells, mainly nuclear and anaphasic bridges, suggesting genotoxic potential. The induction of micronuclei in cells of the F₁ region suggests that the two residues have mutagenic potential. Thus, caution is advised when applying these effluents in the environment.

Toxic effects of environmental pollutants: Comparative investigation using Allium cepa L. and Lactuca sativa L

Studies that help understand the mechanisms of action of environmental pollutants are extremely important in environmental toxicology. In this context, assays using plants as models stand out for their simplicity and low performance cost. Among the plants used for this purpose, Allium cepa L. is the model most commonly applied for cytogenotoxic tests, while Lactuca sativa L., already widely used in phytotoxic investigations, has been gaining prominence in cytotoxic analyses. The present study aimed to compare the responses of A. cepa and L. sativa via macroscopic (root growth) and microscopic analyses (cell cycle and DNA fragmentation via TdT-mediated deoxy-uracil nick and labeling (TUNEL) and comet assays) after exposure of their roots to environmental pollutants with known cytogenotoxic mechanisms. Both species presented sensitive and efficient response to the applied tests after exposure to the DNA-alkylating agent Methyl Methanesulfonate (MMS), the heavy metal Cadmium, the aluminum industry waste Spent Potliner (SPL) and the herbicide Atrazine. However, they differed regarding the responses to the evaluated endpoints. Overall, A. cepa was more efficient in detecting clastogenic changes, arising from DNA breakage, while L. sativa rather detected aneugenic alterations, related to chromosome segregation in mitosis. In the tests applied to verify DNA fragmentation (comet and TUNEL assays), A. cepa presented higher sensitivity. In conclusion, both models are efficient to evaluate toxicological risks of environmental pollutants.

Cytotoxicity and genotoxicity of Guaribas river water (Piauí, Brazil), influenced by anthropogenic action

In general, tropical rivers have a great impact on human activities. Bioaccumulation of toxins is a worldwide problem nowadays and has been, historically, overlooked by the supervisory authorities. This study evaluated cytogenotoxic effects of Guaribas river (a Brazilian river) water during dry and rainy seasons of 2014 by using the Allium cepa test system. The toxicogenetic variables, including root growth, mitotic index, and chromosomal aberrations, were analyzed in meristematic cells of A. cepa exposed to water samples taken from the up-, within, and downstream of the city Picos (state: Piauí). The physical-chemical parameters were also analyzed to explain water quality and possible anthropogenic action. Additionally, the presence of heavy metals was also analyzed to explain water quality and possible damaging effects on eukaryotic cells. The results suggest that the river water exerted cytotoxic, mutagenic, and genotoxic effects, regardless of the seasons. In addition, Guaribas river presented physico-chemical values outside the Brazilian laws, which can be a characteristic of human pollution (domestic sewage, industrial, and local agriculture). The genetic damage was positively correlated with higher levels of heavy metals. The pollution of the Guaribas river water may link to the chemical contamination, including the action of heavy metals and their impacts on genetic instability in the aquatic ecosystem. In conclusion, necessary steps should be taken into account for further toxicogenetic studies of the Guaribas river water, as it has an influence in human health of the same region of Brazil.

Evaluation of toxic, cytotoxic and genotoxic effects of phytol and its nanoemulsion

Phytol (PYT) is a diterpenoid having important biological activity. However, it is a water non-soluble compound. This study aims to prepare PYT nanoemulsion (PNE) and evaluation of toxic, cytotoxic and genotoxic activities of PYT and PNE. For this, the PNE was prepared by the phase inversion method. The cytotoxicity test was performed in Artemia salina, while toxicity, cytotoxicity and genotoxicity in Allium cepa at concentrations of 2, 4, 8 and 16 mM. Potassium dichromate and copper sulfate were used as positive controls for the tests of A. salina and A. cepa, respectively. In addition, an adaptation response was detected in A. cepa by using the comet assay. The results suggest that both PYT and PNE exhibited toxic and cytotoxic effects at 4-16 mM in either test system, while genotoxicity at 2-16 mM in A. cepa. PNE exhibited more toxic, cytotoxic and genotoxic effects at 8 and 16 mM than the PYT. However, both PYT and PNE at 2 and 4 mM decreased the index and frequency of damage in A. cepa after 48 and 72 h, suggesting a possible adaptation response or DNA damage preventing capacity. Nanoemulsified PYT (PNE) may readily cross the biological membranes with an increase in bioavailability and produce more toxic, cytotoxic and genotoxic effects in the used test systems.