Inhibition Of Catalase Activity Research Articles

Влияние пирогенного воздействия на биологическую активность чернозема обыкновенного в модельных экспериментах

The influence of the pyrogenic effect on the biological properties of Haplic chernozem was investigated. For this, a series of model experiments was set up to simulate fires of various duration and intensity. A significant change in the biological properties of soils was found, as well as differences in the reactions of biological indicators to the pyrogenic effect. In different experiments, a different nature of changes in the reaction of the soil environment and the content of organic carbon, an increase in the content of readily soluble salts, was established. In all experiments, inhibition of catalase activity was noted, changes in peroxidase activity were more contradictory. In one of the experiments, stimulation of peroxidase activity was found. In order to study the methods of restoring the biological activity of post-pyrogenic soils, a model experiment was carried out using potassium humate, complex mineral fertilizer and phytoremediation. At the same time, no unambiguous results were obtained that would make it possible to recommend methods for the accelerated recovery of post-pyrogenic soils. Keywords: BIODIAGNOSTICS, FIRES, POSTPYROGENIC SOILS, ENZYME ACTIVITY, SOIL RESTORATION

Arjunetin as a promising drug candidate against SARS-CoV-2: molecular dynamics simulation studies

Stem and bark of the tree Terminalia arjuna Wight & Arn. (Combretaceae) has been documented to exhibit therapeutic properties like cardiotonic, anticancer, antiviral, antibacterial, antifungal, hypercholesterolemia, hypolipidemic, and anti-coagulant. Our previous studies have shown that, ethanolic extract of T. arjuna bark exhibits radical scavenging anti-oxidant activity and also effectively inhibited catalase activity. In this study, oleanane triterpenoids type compounds viz., oleanolic acid, arjunolic acid, arjunolitin, arjunetin were isolated from ethanolic bark extract as bio-active compound and their structures were elucidated using 1H, 13C NMR, HR-ESIMS, IR. Of the various compounds, Arjunetin showed significant inhibition of catalase activity as compared to the other compounds. Based on the structural similarity between arjunetin and current antiviral drugs, we propose that arjunetin might exhibit antiviral activity. Molecular docking and molecular dynamics studies showed that arjunetin binds to the binds to key targets of SARS-CoV-2 namely, 3CLpro, PLpro, and RdRp) with a higher binding energy values (3CLpro, −8.4 kcal/mol; PLpro, −7.6 kcal/mol and RdRp, −8.1 kcal/mol) as compared with FDA approved protease inhibitor drugs to Lopinavir (3CLpro, −7.2 kcal/mole and PLpro −7.7 kcal/mole) and Remdesivir (RdRp −7.6 kcal/mole). To further investigate this, we performed 200–500 ns molecular dynamics simulation studies. The results transpired that the binding affinity of Arjunetin is higher than Remdesivir in the RNA binding cavity of RdRp. Based on structural similarity between arjunetin and Saikosaponin (a known antiviral agents) and based on our molecular docking and molecular dynamic simulation studies, we propose that arjunetin can be a promising drug candidate against Covid-19. Communicated by Ramaswamy H. Sarma

Maize catalases localized in peroxisomes support the replication of maize chlorotic mottle virus

Co-infection of maize chlorotic mottle virus (MCMV) with a virus in the Potyviridae family, such as sugarcane mosaic virus, usually leads to maize lethal necrosis (MLN). Over the past decade, MCMV/MLN has emerged in many countries/regions of the world and resulted in serious yield loss in maize production. Although partial functions of some MCMV-encoded proteins have been identified, the host factors related to MCMV replication are poorly understood. Here, we show that maize peroxisomes can form aggregated bodies in MCMV-infected leaf cells. The dsRNA binding-dependent fluorescence complementation assay indicated that the aggregated peroxisomes in maize served as the major replication site of MCMV. In addition, our results revealed that all the three maize catalases were present mostly in peroxisomes in the presence or absence of MCMV. Furthermore, we determined that inhibition of catalase activity or induction of reactive oxygen species (ROS) in maize protoplasts significantly reduced the accumulation of MCMV RNA. In summary, this research reveals the replication site of MCMV and an important role of maize catalases in supporting virus replication. Our results are conducive to understanding the pathogenesis of MCMV and identifying targets for resistance breeding or gene regulation strategies.

The Cyclophilin ROC3 Regulates ABA-Induced Stomatal Closure and the Drought Stress Response of Arabidopsis thaliana.

Drought causes a major constraint on plant growth, development, and crop productivity. Drought stress enhances the synthesis and mobilization of the phytohormone abscisic acid (ABA). Enhanced cellular levels of ABA promote the production of reactive oxygen species (ROS), which in turn induce anion channel activity in guard cells that consequently leads to stomatal closure. Although Cyclophilins (CYPs) are known to participate in the biotic stress response, their involvement in guard cell ABA signaling and the drought response remains to be established. The Arabidopsis thaliana gene ROC3 encodes a CYP. Arabidopsis roc3 T-DNA mutants showed a reduced level of ABA-activated S-type anion currents, and stomatal closure than wild type (WT). Also, roc3 mutants exhibited rapid loss of water in leaf than wild type. Two complementation lines of roc3 mutants showed similar stomatal response to ABA as observed for WT. Both complementation lines also showed similar water loss as WT by leaf detached assay. Biochemical assay suggested that ROC3 positively regulates ROS accumulation by inhibiting catalase activity. In response to ABA treatment or drought stress, roc3 mutant show down regulation of a number of stress responsive genes. All findings indicate that ROC3 positively regulates ABA-induced stomatal closure and the drought response by regulating ROS homeostasis and the expression of various stress-activated genes.

An in vitro and in silico study to explore the response of catalase to 4-chlorophenol and their interacting mechanisms

The present study conducted a novel strategy combining cellular and molecular methods to explore whether catalase (CAT) response is involved in 4-chlorophenol (4-CP) induced cytotoxicity and to investigate the detailed mechanism of CAT response to 4-CP. The results showed that the inhibition of CAT activity was not the primary cause of oxidative stress and cytotoxicity under 4-CP exposure. The decrease of intracellular CAT activity was contributed by the modulation of reactive oxygen species and the activity inhibition of CAT molecule. Isothermal titration calorimetry and molecular docking studies found that 4-CP binds to CAT with one binding site at the cavity between helical domain and threading arm majorly through van der Waals forces and hydrogen bonding. UV–vis absorption spectra showed that the binding unfolded the polypeptide chains of CAT and did not exhibit direct interruptions to heme groups around the active sites. Circular dichroism spectra found that the interaction caused secondary structure changes in CAT with a loss of α-helix content, which could be explained by the interaction of 4-CP with the residue HIS 62 in the binding site. Resonance light scattering spectra found that the aggregation state of CAT reduced under 4-CP exposure. These structural changes could influence the conformation around the active sites and then lead to the inhibition of molecular activity.

Enhanced Tolerance to Cowpea Mosaic Virus in Vigna unguiculata L. Plants Pretreated with Salicylic Acid

Cowpea mosaic virus (CPMV) is one of the most economically critical pathogen infecting cowpea plants. Recently, eco-friendly strategies have been developed for enhancing the tolerance level of crops against virus infection. The present investigation evaluates the effect of salicylic acid (SA) on the response of three cultivars of Vigna unguiculata plants [Libyan Black eye (LB), Libyan red eye (LR) and Egyptian Black eye hybrid (Kafr El Sheikh1cv.; EBH)] to CPMV. The leaves of 15-d old cowpea plants were foliar sprayed with 50 or 100 µM SA, 24 h before inoculation with CPMV. Most measured growth indices as well as total photosynthetic pigment and photosynthetic efficiency were all diminished in CPMV inoculated plants of all three cultivars. Nonetheless, SA utilization could enhance cowpea growth and lower virus severity, notably in the Libyan cultivars. Furthermore, the CPMV-induced oxidative damages as well as phenolics accumulation were lesser upon SA application to all infected cowpea cvs. CPMV infection triggered an increase in catalase (CAT), guaiacol peroxidae (GPX) and polyphenol oxidase (PPO) activity in all cowpea cultivars, except for the EBH cultivar where the PPO was insignificantly changed. Interestingly, SA pretreatment significantly inhibited CAT activity only in the LR and LBH cv. compared to infected plants while it induced GPX and PPO in the three tested cultivars, most obviously in the Lybian ones. In general, SA was effective in induction of systematic resistance to CPMV in the two Libyan cowpea cultivars rather than the Egyptian one

Effects of Trichloroethylene on p53 and Bcl-2 Expression, Chromosome Loss and Catalase Activity Inhibition in Human

Trichloroethylene (TCE) is a common organic solvent that has been widely used in industrial applications.TCE is highly lipophilic and readily absorbed into the circulation following oral, dermal or inhalationexposure. The purpose of this study is to examine the alterations of p53 and Bcl-2 expression, chromosomeloss and catalase activity inhibition after treatment with TCE. Human lymphocytes were cultured withvarious doses of TCE for 24 h. Quantitative RT-PCR (qRT-PCR) technique, chromosome culture techniqueand catalase activity assay were performed in human lymphocyte cultures. The results of Quantitative RTPCR (qRT-PCR) analysis showed up-regulated expression in the experimental groups comparison with thecontrol groups of p53 gene [0.016 mM/L (1.4-fold) and Bcl-2 gene [0.008 mM/L (1.4-fold) and 0.016mM/L (1.6-fold)]. Loss of chromosome 8 and 22 were observed. Catalase activity was reduced whenTCE concentration increased (p<0.05). It is indicated that TCE effects on p53 and Bcl-2 gene expression,chromosome loss and catalase activity inhibition. These effects may lead to the onset of cancer in the future.

A novel pathogenicity determinant hijacks maize catalase 1 to enhance viral multiplication and infection.

Pathogens have evolved various strategies to overcome host immunity for successful infection. Maize chlorotic mottle virus (MCMV) can cause lethal necrosis in maize (Zea mays) when it coinfects with a virus in the Potyviridae family. However, the MCMV pathogenicity determinant remains largely unknown. Here we show that the P31 protein of MCMV is important for viral accumulation and essential for symptom development. Ectopic expression of P31 using foxtail mosaic virus or potato virus X induced necrosis in systemically infected maize or Nicotiana benthamiana leaves. Maize catalases (CATs) were shown to interact with P31 in yeast and in planta. P31 accumulation was elevated through its interaction with ZmCAT1. P31 attenuated the expression of salicylic acid (SA)-responsive pathogenesis-related (PR) genes by inhibiting catalase activity during MCMV infection. In addition, silencing of ZmCATs using a brome mosaic virus-based gene silencing vector facilitated MCMV RNA and coat protein accumulation. This study reveals an important role for MCMV P31 in counteracting host defence and inducing systemic chlorosis and necrosis. Our results have implications for understanding the mechanisms in defence and counter-defence during infection of plants by various pathogens.

Promising Potential of Crude Polysaccharides from Sparassis crispa against Colon Cancer: An In Vitro Study.

The aim of the present study was to evaluate in vitro the beneficial potential of crude polysaccharides from S. crispa (CPS) in one of the most common cancer types—colon cancer. The determination of the chemical composition of CPS has revealed that it contains mostly carbohydrates, while proteins or phenolics are present only in trace amounts. 1H NMR and GC–MS methods were used for the structural analysis of CPS. Biological activity including anticancer, anti-inflammatory and antioxidant properties of CPS was investigated. CPS was found to be non-toxic to normal human colon epithelial CCD841 CoN cells. Simultaneously, they destroyed membrane integrity as well as inhibited the proliferation of human colon cancer cell lines: Caco-2, LS180 and HT-29. Antioxidant activity was determined by various methods and revealed the moderate potential of CPS. The enzymatic assays revealed no influence of CPS on xanthine oxidase and the inhibition of catalase activity. Moreover, pro-inflammatory enzymes such as cyclooxygenase-2 or lipooxygenase were inhibited by CPS. Therefore, it may be suggested that S. crispa is a valuable part of the regular human diet, which may contribute to a reduction in the risk of colon cancer, and possess promising activities encouraging further studies regarding its potential use as chemopreventive and therapeutic agent in more invasive stages of this type of cancer.

Are Microplastics Impairing Marine Fish Larviculture?—Preliminary Results with Argyrosomus regius

The presence of small-sized (<300 µm) microplastics (MPs) in aquaculture facilities may threaten finfish hatchery, as their (in)voluntary ingestion by fish larvae may compromise nutritional requirements during early ontogeny, and consequently larval health and performance. Thus, we addressed the short-term effects (7 h) of polyethylene microplastics (0.1, 1.0, 10 mg/L, PE-MPs) in meagre larvae Argyrosomus regius (15 dph) in the presence/absence of food. Larval feeding behavior, oxidative stress status, neurotoxicity, and metabolic requirements were evaluated. Results showed that meagre larvae ingested PE-MPs regardless of their concentration, decreasing in the presence of food (Artemia metanauplii). The presence of PE-MPs compromised larval feeding activity at the highest concentration. Under starvation, exposed larvae activated the antioxidant defenses by increasing the total glutathione levels and inhibiting catalase activity, which seemed efficient to prevent oxidative damage. Such larvae also presented increased energy consumption potentially related to oxidative damage prevention and decreased neurotransmission. Biochemical responses of fed larvae showed a similar trend, except for LPO, which remained unaffected, except at 0.1 mg/PE-MPs/L. Our results suggest that small-sized MPs in finfish hatcheries may compromise larvae nutritional requirements, but at considerably higher levels than those reported in marine environments. Nevertheless, cumulative adverse effects due to lower MPs concentrations may occur.

Toxic mechanism of pyrene to catalase and protective effects of vitamin C: Studies at the molecular and cell levels

Polycyclic aromatic hydrocarbons, distributing extensively in the soil, would potentially threaten the soil organisms (Eisenia fetida) by triggering oxidative stress. As a ubiquitous antioxidant enzyme, catalase can protect organisms from oxidative damage. To reveal the potential impact of polycyclic aromatic hydrocarbon pyrene (Pyr) on catalase (CAT) and the possible protective effect of Ascorbic acid (vitamin C), multi-spectral and molecular docking techniques were used to investigate the influence of structure and function of catalase by pyrene. Fluorescence and circular dichroism analysis showed that pyrene would induce the microenvironmental changes of CAT amino acid residues and increase the α-helix in the secondary structure. Molecular simulation results indicated that the main binding force of pyrene around the active center of CAT is hydrogen bonding force. Furthermore, pyrene inhibited catalase activity to 69.9% compared with the blank group, but the degree of inhibition was significantly weakened after vitamin C added into the research group. Cell level experiments showed that pyrene can increase the level of ROS in the body cavity cell of earthworms, and put the cells under the threat of potential oxidative damage. Antioxidants-vitamin C has a protective effect on catalase and maintains the stability of intracellular ROS levels to a certain extent.

Diclofenac and caffeine inhibit hepatic antioxidant enzymes in the freshwater fish Astyanax altiparanae (Teleostei: Characiformes)

Although concentrations of pharmaceutical compounds in aquatic ecosystems are low, they can cause toxic effects on organisms. The aim of this study was to evaluate the effects of diclofenac (DCF), a non-steroidal anti-inflammatory drug, and caffeine (CAF), a central nervous system stimulant, both alone or combined, in Astyanax altiparanae males under acute exposure (96 h), measuring neurotoxicity biomarkers, antioxidant response and damage at biochemical and cellular levels. DCF concentration in water, separated and combined, was 3.08 mg L−1 and that of CAF was 9.59 mg L−1. To assess neurotoxicity, brain and muscle acetylcholinesterase (AChE) activities were measured. To evaluate oxidative stress, the enzymatic activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione S-transferase (GST), as well as lipoperoxidation (LPO), were analyzed in liver and gills. Activity of hepatic cyclooxygenase (COX) was also evaluated. Genotoxicity was assessed in blood using comet assay and micronucleus test, as well as nuclear abnormalities. DCF and CAF, alone or combined, had neither effect on AChE activity, nor in the activity of SOD, CAT, GPx and GST in gills. In liver, DCF inhibited SOD and GPx activity, CAF inhibited CAT activity, the mixture inhibited SOD and GST activity; although only fish exposed to CAF showed increased hepatic LPO. Under these experimental conditions, no effect on COX activity was observed, nor cytotoxic and genotoxic damage. The most pronounced effects were caused by the drugs separately, since both compounds altered the enzymes, but only CAF triggered LPO, showing more harmful effects.

Effect of Fluoride on Germination, Early Growth and Antioxidant Enzymes Activity of Three Winter Wheat (Triticum aestivum L.) Cultivars

This paper assesses the impact of sodium fluoride on the morphological parameters and activity of catalase and peroxidase during the germination and root growth phases of three winter wheat cultivars: Tobak, Dalewar, and Arkadia. During examination, the seeds were placed on plastic Petri dishes with an NaF solution at concentrations of 0 (control), 2.5, 5.0, 8.0, and 10.0 mmol dm−3. The obtained results have shown a decrease in germination, inhibition of root growth, and inhibition of catalase activity, both in the embryos and roots of all tested winter wheat cultivars. The observed effects have been strengthened with the increase of the fluoride concentration. However, the effect of NaF on the peroxidase activity has been dependent on the wheat cultivar. It is difficult to state unequivocally which of the tested winter wheat cultivars has been characterized by the highest sensitivity to fluoride. An η2 analysis has confirmed that the NaF concentration has a greater effect than the winter wheat cultivar on the activity of the determined antioxidant enzymes.

Oxidative stress and genotoxicity in Rhinella arenarum (Anura: Bufonidae) tadpoles after acute exposure to Ni-Al nanoceramics

The employ of nanomaterials (NMs) has exponentially grown due to the large number of technological advances in industrial, pharmaceutical and medical areas. That is the case of alumina (Al) nanoparticles which are extensively employed as support in heterogeneous catalysis processes. However, these NMs can cause great toxicity because of their ubiquitous properties, such as extremely small size and high specific surface area. So, it is required to assess the potential deleterious effects of these NMs on living organisms. In the present study, we analyze the oxidative stress and genotoxic potential of a nanoceramic catalyst Ni/<gamma>-Al2O3 (NC) and the NMs involved in their synthesis, <gamma>-Al2O3 support (SPC) and NiO/<gamma>-Al2O3 precursor (PC) on Rhinella arenarum larvae. Biomarkers of oxidative stress and genotoxic damage were measured in tadpoles exposed to 5 and 25 mg/L of each NMs for 96 h. The results indicated an inhibition of catalase activity in tadpoles exposed to both concentrations of PC and to 25 mg/L of SPC and NC. Moreover, both exposure concentrations of PC and NC significantly inhibited superoxide dismutase activity. Exposure to the three NMs caused inhibition of glutathione S-transferase activity, but there were no significant variations in reduced glutathione levels. Oxidative stress damage (lipid peroxidation) was observed in tadpoles treated with 25 mg/L PC, while the other treatments did not produce alterations. The MNs frequency significantly increased in larvae exposed to 25 mg/L PC indicating irreversible genotoxic damage. The results show that these NMs exert genotoxic effects and antioxidant defense system disruption in R. arenarum larvae.

Dermal, histological anomalies with variations in enzyme activities of the earthworms Lampito mauritii and Drawida willsi after short term exposure to organophosphate pesticides

Monocrotophos and glyphosate are two potent organophosphate pesticides used on agricultural farms in India to control insect pests and weeds, respectively. Consistent application of these chemicals poses a risk of residual soil contamination with possible adverse implications on non-target organisms, like earthworms. The present study evaluates the impacts of these pesticides on the skin, muscles and certain biochemical parameters such as protein content, lipid peroxidation (LPX) level, activities of lactate dehydrogenase (LDH), acetylcholinesterase (AChE) and catalase (CAT) of two tropical earthworms Drawida willsi and Lampito mauritii. Monocrotophos at 1.0, 2.0, 3.0 g/kg soil and glyphosate at 0.1, 0.15, 0.2 g/kg soil were used for the experiment. At high concentrations, both pesticides induced lesions and skin undulation in the earthworms. In L. mauritii, the postclitellar region indicated muscle disorganization with high concentrations of monocrotophos. The lowest protein level was recorded in D.willsi and L. mauritii with high concentrations of monocrotophos. L. mauritii exhibited maximum LPX at high concentrations of glyphosate. Both the earthworms indicated the least LDH activity with high pesticide concentration. Minimal AChE activity in L. mauritii was observed with a high concentration of glyphosate. A high concentration of monocrotophos inhibited CAT activity in L. mauritii. The variable response of the selected morpho-histological and biochemical parameters in the earthworms to different pesticide concentrations could be useful early warning biomarkers to evaluate soil residual toxicity.

Performance of Hylocereus (Cactaceae) species and interspecific hybrids under high-temperature stress

High temperatures limit the successful cultivation of the Hylocereus species on a global basis. We aimed to investigate the degree of heat tolerance in three species, namely, the diploids Hylocereus undatus and H. monacanthus, and the tetraploid H. megalanthus, and nine of their interspecific-interploid hybrids. Rooted cuttings were exposed to heat stress (45/35 °C) or control conditions (25/20 °C) for eight days. Initially, the plants were screened for their tolerance to heat stress and ranked into four heat tolerance categories: good tolerance, moderate tolerance, low tolerance, or sensitive, according to the decrease in the maximum quantum efficiency of photosystem II (Fv/Fm) and visual stem damage. The physiological and biochemical performances of the parental species and of three hybrids representing three different heat-tolerance categories were further analyzed in depth. H. megalanthus (classified as heat sensitive) showed a 65% decrease in Fv/Fm and severe visual stem damage, along with a marked reduction in total chlorophyll content, a large increase in malondialdehyde, and inhibition of catalase activity. H. undatus and H. monacanthus, (classified as low-tolerance species) exhibited slight stem “liquification.” The good-tolerance hybrid Z-16 exhibited the best performance under heat stress (21% decrease in Fv/Fm) and the absence of stem damage, coupled with a small decrease in total chlorophyll content, a slight increase in malondialdehyde, high antioxidant activity, and proline accumulation progressing with time. Our findings revealed that most of the hybrids performed better than their parental species, indicating that our breeding programs can provide Hylocereus cultivars suitable for cultivation in heat-challenging regions.

Catalase is required for peroxisome maintenance during adipogenesis

Although obesity contributes to the onset and pathogenesis of metabolic diseases, it has been repeatedly demonstrated that being overweight or mildly obese carries a survival advantage compared with being thin or normal-weight. This relationship is called the obesity paradox. Hence, it is necessary to clarify the underlying mechanism of obesity onset for the prevention and treatment of these diseases. Catalase is distributed in peroxisomes under normal redox conditions and catalase activity is increased during the differentiation of 3T3-L1 preadipocytes to adipocytes. Although peroxisomes are responsible for lipid metabolism, the role of peroxisomal catalase in the process of lipid accumulation remains unclear. The present study aimed to investigate the relationships among catalase activity, peroxisome content, and lipid accumulation during the differentiation of 3T3-L1 preadipocytes to adipocytes. Increased catalase activity and lipid accumulation were observed during the differentiation of preadipocytes. Silencing of catalase by small interfering RNA or treatment with 3-amino-1,2,4-triazole (3-AT), a catalase inhibitor, resulted in reduced lipid accumulation. Inhibition of catalase activity in peroxisomes increases hydrogen peroxide (H2O2) levels, which results in a reduction of peroxisome content. Extracellular H2O2 had no influence on lipid accumulation during differentiation. The occurrence of autophagy was clearly enhanced in cells treated with 3-AT. Spautin-1, an inhibitor of autophagy flux, protected against a reduction in lipid accumulation by treatment with 3-AT. Our data provide evidence that catalase protects against the degradation of peroxisomes via the occurrence of autophagy triggered by the generation of H2O2 in peroxisomes. These results suggest that catalase in peroxisomes is crucial to adipogenesis.

Toxicity evaluation of the active ingredient acetamiprid and a commercial formulation (Assail® 70) on the non-target gastropod Biomphalaria straminea (Mollusca: Planorbidae).

Neonicotinoids emerged as an environmentally safe alternative to previous generations of insecticides becoming one of the most widely applied in modern agriculture. Nevertheless, they have been reported to affect several non-target organisms. Most toxicity studies focus on the effects on pollinators or terrestrial invertebrates and evaluate either the active ingredient or the commercial formulation. In the present study, we aimed to assess the long-term effects of the active ingredient acetamiprid and a broadly used commercial formulation (Assail® 70) on the non-target freshwater gastropod Biomphalaria straminea using a battery of biomarkers. A 14 day-exposure of adult organisms to both active ingredient and commercial formulation increased carboxylesterase activity and glutathione content, inhibited superoxide dismutase activity and decreased reactive oxygen species levels. The commercial formulation additionally increased glutathione S-transferase activity and inhibited catalase activity. The results indicate a greater toxicity of the commercial formulation than that of the active ingredient alone. Cholinesterase activity, development and offspring survival of B. straminea were not impaired. We conclude that the toxicity of acetamiprid on this gastropod species is mainly related to effects on detoxification and oxidative metabolism responses. This study provides novel information about the adverse effects of the active ingredient and a commercial formulation of a widely used neonicotinoid on a non-target aquatic species.

Impact of wastewater-borne nanoparticles of silver and titanium dioxide on the swimming behaviour and biochemical markers of Daphnia magna: An integrated approach

Due to their widespread use, silver (Ag) and titanium dioxide (TiO2) nanoparticles (NPs) are commonly discharged into aquatic environments via wastewater treatment plants. The study was aimed to assess the effects of wastewater-borne AgNPs (NM-300 K; 15.5 ± 2.4 nm; 25−125 μg L−1) and TiO2NPs (NM-105; 23.1 ± 6.2 nm; 12.5−100 μg L−1), from a laboratory-scale wastewater treatment plant, on Daphnia magna, at individual and subcellular level. For effect comparison, animals were also exposed to ASTM-dispersed NPs at the same nominal concentrations.The behaviour of D. magna was evaluated through monitoring of swimming height and allocation time for preferred zones after 0 h and 96 h of exposure. Biochemical markers of neurotransmission, anaerobic metabolism, biotransformation, and oxidative stress were subsequently determined. No 96-h EC50 (immobilization ≤ 4 %) could be obtained with wastewater-borne NPs and ASTM-dispersed TiO2NPs, whereas the ASTM-dispersed AgNPs resulted in an immobilization 96-h EC50 of 113.8 μg L−1. However, both wastewater-borne and ASTM-dispersed TiO2NPs, at 12.5 μg L−1, caused immediate (0 h) alterations on the swimming height. Allocation time analyses showed that animals exposed to ASTM-dispersed AgNPs spent more time on the surface and bottom at 0 h, and in the middle and bottom at 96 h. This pattern was not observed with ASTM-dispersed TiO2NPs nor with wastewater-borne AgNPs and wastewater-borne TiO2NPs. At the biochemical level, the more pronounced effects were observed with wastewater-borne AgNPs (e.g. induction of lactate dehydrogenase and glutathione S-transferase activities, and inhibition of catalase activity).This integrative approach showed that: (i) the behavioural and biochemical response-patterns were distinct in D. magna exposed to environmentally relevant concentrations of wastewater-borne and ASTM-dispersed NPs; (ii) the most pronounced effects on allocation time were induced by ASTM-dispersed AgNPs; and (iii) at the subcellular level, wastewater-borne AgNPs were more toxic than wastewater-borne TiO2NPs. This study highlights the need for the assessment of the effects of wastewater-borne NPs under realistic exposure scenarios, since processes in wastewater treatment plants may influence their toxicity.

Biochemical responses and DNA damage induced by herbicide QYR301 in earthworm (Eisenia fetida).

QYR301, a novel herbicidal inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), has great potential for resistant weed control in paddy fields, but massive use of pesticides may result in toxicity to soil non-target organisms. Thus, this study was designed to assess subchronic toxicity of different doses of QYR301 in artificial soil (0, 0.1, 1.0, 2.5, and 5.0mgkg-1) to earthworms (Eisenia fetida) on days 7, 14, 21, and 28 after exposure, using biomarkers of reactive oxygen species (ROS) and malondialdehyde (MDA) contents, activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST), and DNA damage. The ROS content significantly increased for all treatments on 7 and 14 days then decreased, and recovered to control level for 0.1 and 1.0mgkg-1 treatment on day 28. Concerning enzymes activities, QYR301 increased POD, SOD, and GST activities, but inhibited CAT activity. Except for POD activity, SOD, CAT, and GST activities of 0.1mgkg-1 group recovered to control level on day 28. Also, the MDA content of 0.1mgkg-1 group reached control level on day 28. However, DNA damage was observed for all treatments throughout the experiment and it increased with increasing doses and time except for 5.0mgkg-1 treatment on day 28. These results suggested that QYR301 induced excessive ROS production leading to oxidative stress in earthworms, which caused lipid membrane peroxidation and DNA damage ultimately. The findings could provide a theoretical foundation for assessing ecological damage of QYR301 to soils and a guide for future QYR301 applications.