Responses of the antioxidant defenses of the Goldfish Carassius auratus, exposed to 2,4-dichlorophenol

Larvicidal and Fungicidal Activity of the Leaf Essential Oil of Five Myrtaceae Species

Myrtaceae is one of the most diverse and abundant botanical families, exhibiting wide diversity in the chemical composition of essential oils (EOs). EOs have various biotechnological applications such as controlling the populations of organisms that negatively impact humans. This study aimed to extract EOs from Myrtaceae species, chemically characterize them, and evaluate their larvicidal and fungicidal effects. EOs were extracted from the leaves of Eugenia brasiliensis, Eugenia uniflora, Psidium cattleyanum, Psidium guajava, and Syzygium cumini by hydrodistillation for 3 h and characterized by chromatographic analysis. Larvaes of Aedes aegypti and colonies of Fusarium oxysporum were subjected to increasing EO concentrations to determine the larvicidal and fungicidal potential. The EOs of Eugenia and Psidium species are primarily composed of sesquiterpenes (>80 %), whereas S. cumini EO is rich in monoterpenes (more than 60 %). The Eugenia species had similar amounts of oxygenated monoterpenes, which may explain their higher larvicidal potential compared to other species, with CL50 of 86.68 and 147.46 PPM, respectively. In addition to these two study species, S. cumini showed a high inhibition of fungal growth, with more than 65 % inhibition. We demonstrated that the actions of five EOs from Myrtaceae with different biological activities are associated with chemical diversity.

Biochemical and phytochemical responses of Ammi visnaga L. (Apiaceae) callus culture elicited by SiO2 and graphene Oxide-SiO2 nanoparticles

Ammi visnaga L. is an enriched medicinal plant with medicinally important compounds. Two types of nanoparticles (NPs) including silica (SiO₂) and graphene oxide bound with SiO₂ (GO-SiO₂) NPs at different concentrations (0, 15, 25 mg L^-1) were used as elicitors to investigate their effects on callus morphology, H₂O₂ content, total phenolic content (TPC), total flavonoids content (TFC), ferric reducing/antioxidant power (FRAP), and few antioxidant enzymes such as catalase (CAT), guaiacol peroxidase (GPX), superoxide dismutase (SOD), ascorbate peroxidase (APX), and polyphenol oxidase (PPO) in the callus cultures of A. visnaga. The effects of elicitation of both NPs on calli were observed using a scanning electron microscope (SEM). The 15 mg L^-1 concentration of GO-SiO₂ NPs produced the highest TPC (193.3 mg GAE g^-1 FW), CAT (13.1 U mg^-1 Protein), GPX (0.0089 U mg^-1 Protein), and APX (0.079 U mg^-1 Protein). Whereas, the maximum content of H₂O₂ (0.68 μmol g^-1 FW), FRAP (0.0092 μmol mg^-1), and TFC (62.27 mg QE g^-1 FW) was observed at 25 mg L^-1 and 15 mg L^-1 of SiO₂ NPs, respectively. Conclusively, in the callus culture of A. visnaga, the 15 mg L^-1 concentration of GO-SiO₂ NPs was the most suitable dosage for enhancing the enzymatic antioxidant activities (CAT, GPX, APX) and TPC, rather than SiO₂ NPs.

Efficient activation of peroxodisulfate by novel bionic iron-encapsulated biochar: The key roles of electron transfer pathway and reactive oxygen species evolution

In this study, a novel iron-encapsulated biochar (Fe@BC) was prepared using the biomass cultivated with an iron-containing solution. The iron in Fe@BC showed the phase change from Fe₃O₄ to α-Fe, and to CFe_15.1, with the increase of pyrolysis temperature (500-900 °C), and a graphene shell formed on the surface of Fe@BC. In addition, the signals assigned to the π-π* shake up, pyridinic N, graphitic N, and defects of Fe@BC were found to be stronger as the pyrolysis temperature increased. The F4@B9 sample, which was prepared at 900 °C, exhibited an excellent performance (98.01 %) to activate peroxydisulfate (PDS) for the degradation of 2,4-dichlorophenol. Electron paramagnetic resonanceand chemical quenching experiments revealed that reactive oxygen radicals (ROS) including sulfate radical (•SO₄^-), hydroxyl radical (•OH), superoxide radical (•O₂^-), and singlet oxygen (¹O₂) existed in the F4@B9/PDS system. Furthermore, the micro-electrolysis process facilitated the generation of •O₂^- (12.35 %) and ¹O₂ (6.49 %) compared with the pure PDS system. Density functional theory revealed that, for the F4@B9-activated PDS process, the graphene shell of F4@B9 served as catalytic active sites as well. According to the correlation analysis, the iron specie of CFe_15.1 was more favorable for the generation of ROS than α-Fe. Also, π-π* shake up, pyridinic N, graphitic N, and defects participated in the PDS activation. This study provides a new method for the preparation of high-performance catalysts from naturally grown biomass with high iron contents.

Assessment of deep eutectic solvents toxicity in zebrafish (Danio rerio)

Deep Eutectic Systems (DES) have emerged as a "green alternative" to organic solvents and have been coined as biocompatible and biodegradable. However, the number of studies concerning the real biodegradability and biocompatibility are scarce. Thus, to study the toxicity of certain DES, two different approaches were used: i) zebrafish exposure via water, where the system (DES) was tested at potentially realistic environmental concentrations and ii) via intraperitoneal injection, where the system was tested in different concentrations, relevant to the pharmaceutical industry. These studies were performed using zebrafish, a standardized animal model often used in biomedicine and toxicological assays. The results show low toxicity according to tested concentrations (up to 73.47 μM), when the system CA:T:W, with a 2:1:3 molar ratio, was tested through exposure via water and also in the intraperitoneal injection tests with concentrations up to 6000 μM. The activity of different enzymes involved in antioxidant pathways (glutathione S-transferase, catalase, glutathione peroxidase), the total antioxidant capacity (TAC) and lipoperoxidation (MDA content) were determined suggesting low toxicity of the tested system (DES). The promising results herein presented show that DES present the potential to be used as the new class of green solvents, not only for use in the pharmaceutical industry, but also in cosmetic and chemical engineering processes without causing negative impact on living organisms.

A kinetic model for 2,4-dichlorophenol adsorption and hydrodechlorination over a palladized biofilm

Adsorption and catalytic hydrodechlorination (HDC) of aqueous 2,4-DCP by palladium nanoparticles (Pd0NPs) associated with a biofilm (i.e., a Pd0-biofilm) was investigated in terms of the removal efficiency of 2,4-DCP, dechlorinated product selectivity, and reduction kinetics. Experiments were executed with Pd0-biofilm and with abiotic Pd0NPs-film alone. The 2,4-DCP-adsorption capacity of Pd0-biofilm was 2- to 5-fold greater than that of abiotic Pd0NPs-film, and the adsorption accelerated dechlorination by Pd0-biofilm, including selectivity to phenol instead of mono-chlorophenols. A mechanistic kinetic model was developed to represent the sequential adsorption and reduction processes. Modeling results represented well the removal of 2,4-DCP and quantified that Pd0-biofilm had a strong affinity for adsorbing 2,4-DCP. The strong adsorption increased the volume-averaged concentration of 2,4-DCP concentration inside the Pd0-biofilm, compared to the concentration in the bulk liquid. This increase in the local concentration of 2,4-DCP led to a 2- to 4-fold increase in the reduction rate of 2,4-DCP in Pd0-biofilm, compared to abiotic Pd0NPs-film. Thus, coupling Pd0NPs with the biofilm promoted 2,4-DCP removal and full dechlorination despite its low concentration in bulk water.

Eugenia uniflora, Melaleuca armillaris, and Schinus molle essential oils to manage larvae of the filarial vector Culex quinquefasciatus (Diptera: Culicidae)

Populations of Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) have shown resistance to insecticides of the carbamate and organophosphate classes. The objective of this study was to assess the susceptibility of C. quinquefasciatus larvae to essential oils from leaves of Eugenia uniflora L., Melaleuca armillaris (Sol. ex Gaertn.) Sm., and Schinus molle L and C. quinquefasciatus larvae's biochemical responses after their exposure to these leaves. The essential oils were chemically analyzed by GC and GC/MS. First, the lethal concentration for 50% (LC₅₀) values was estimated using different concentrations of essential oils and probit analysis. The larvae were exposed for 1 h at the LC₅₀ estimated for each essential oil. The susceptibility of the larvae to essential oils was evaluated using the following biochemical parameters: concentrations of total protein and reduced glutathione; levels of production of hydrogen peroxide and lipid peroxidation; and the activity of the enzyme acetylcholinesterase (AChE). The main chemical constituents in E. uniflora were E-β-ocimene, curzerene, germacrene B, and germacrone; in M. armillaris were 1,8-cineole and terpinolene; and in S. molle were sabinene, myrcene, and sylvestrene. The essential oils had LC₅₀ values between 31.52 and 60.08 mg/L, all of which were considered effective. All of them also promoted changes in biochemical parameters when compared to the control treatment. The essential oils of S. molle and E. uniflora inhibited the activity of the AChE enzyme, and the essential oil of M. armillaris increased it. All essential oils had larvicidal activity against C. quinquefasciatus, but the essential oil of E. uniflora was the most efficient. Thus, the findings of the present study suggest that the essential oil of E. uniflora can be considered promising for the development of botanical larvicides.

Hematotoxic, oxidative and genotoxic damage in rainbow trout (Oncorhynchus mykiss) after exposure to 3-benzoylpyridine

Pyridine is a basic heterocyclic organic compound. The pyridine ring is present in many important compounds, including agricultural chemicals, medicines and vitamins. Due to their widespread industrial use, bioaccumulation and non-target toxic effects are being considered as a great risk to human and environmental health. In this study, we aimed to evaluate the hematological, oxidative and genotoxic damage potentials by different concentrations (1, 1.5, and 2 g/L) of the ketone 3-Benzoylpyridine (3BP) on rainbow trout (Oncorhynchus mykiss). Alterations in the biomarker levels of oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG)), apoptosis (Caspase-3), malondialdehyde (MDA) as well as antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), myeloperoxidase (MPO), paraoxonase (PON), and arylesterase (AR) were assessed in brain, liver, gill and blood tissues. Acetylcholinesterase (AChE) activity was also determined in brain tissue. In addition, we analyzed micronucleus (MN) rates and hematological indices of total erythrocyte count (RBC), total leukocyte count (WBC), hemoglobin (Hb), hematocrit (Hct), total platelet count (PLT), mean cell hemoglobin concentration (MCHC), mean cell hemoglobin (MCH), and mean cell volume (MCV) in blood. LC₅₀-96h value of 3BP was calculated as 5.2 g/L from the data obtained. A significant decrease in brain AChE activity was determined in clear time and dose dependent manners. While SOD, CAT, GPx, PON, and AR levels were decreased, MDA, MPO, 8-OHdG and Caspase-3 levels were increased in all tissues (p < 0.05). Again, the 3BP led to increases of MN formation at all applied concentrations in the rates of between 45.4 and 72.7%. Significant differences (p < 0.05) were found out in between all studied hematology parameters between 3BP-exposed and the control fish. In conclusion, ours study firstly indicated that the treatment doses of 3BP induced distinct hematological and oxidative alterations as well as genotoxic damage in rainbow trout.

Co-removal of 2,4-dichlorophenol and nitrate using a palladized biofilm: Denitrification-promoted microbial mineralization following catalytic dechlorination

The effects of nitrate on 2,4-dichlorophenol (2,4-DCP) dechlorination and biodegradation in a hydrogen (H₂)-based palladized membrane biofilm reactor (Pd-MBfR) were studied. The Pd-MBfR was created by synthesizing palladium nanoparticle (Pd⁰NPs) that spontaneously associated with the biofilm to form a Pd⁰-biofilm. Without input of nitrate, the Pd-MBfR had rapid and stable catalytic hydrodechlorination: 93% of the 100-μM influent 2,4-DCP was continuously converted to phenol, part of which was then fermented via acetogenesis and methanogenesis. Introduction of nitrate enabled phenol mineralization via denitrification with only a minor decrease in catalytic hydrodechlorination. Phenol-degrading bacteria capable of nitrate respiration were enriched in the Pd⁰-biofilm, which was dominated by the heterotrophic genera Thauera and Azospira. Because the heterotrophic denitrifiers had greater yields than autotrophic denitrifiers, phenol was a more favorable electron donor than H₂ for denitrification. This feature facilitated phenol mineralization and ameliorated denitrification inhibition of catalytic dechlorination through competition for H₂. Increased nitrite loading eventually led to deterioration of the dechlorination flux and selectivity toward phenol. This study documents simultaneous removal of 2,4-DCP and nitrate in the Pd-MBfR and interactions between the two reductions.

Treatment of oxidative stress, apoptosis, and DNA injury with N-acetylcysteine at simulative pesticide toxicity in fish

Pesticide toxicities are common in aquatic ecosystems and affects aquatic livings negative. Therefore, it is important to strengthen the antioxidant system in aquatic organisms and to protect the organisms against these toxic chemicals. In this study, the simulative toxicity was established to the fish then the healing process was followed. For this purpose, rainbow trout Oncorhynchus mykiss exposed to cypermethrin and left to the recovery process with either N-acetyl cysteine (an antioxidant, 0.5 mM-1.0 mM concentrations) or no intervention (self-healing) for 96 h. In this context, paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO), antioxidant enzymes (SOD, CAT, GPx), acetylcholinesterase (AChE) activities as well as MDA, caspase-3 and 8-OHdG levels were measured in fish gills, liver and kidney tissues. In addition, trace element tests were performed in the tissues sampled for each group. At the result of pesticide exposure, SOD, CAT, GPx, PON, AR and AChE activities were increased but MDA, MPO, caspase-3 and 8-OHdG levels were decreased in N-acetyl cysteine (NAC) treated groups in all tissues compared to self-healing group (p < 0.05). When the element analysis of the samples was examined, tissue-based differences were observed significantly in all application groups (p < 0.05). Considering the results of the study, it was found that NAC administration at high concentration (1.0 Mm NAC) was more effective on pesticide toxicity. It was concluded that the most sensitive tissue was the kidney.

Dechlorination of 2,4-dichlorophenol in a hydrogen-based membrane palladium-film reactor: Performance, mechanisms, and model development

We created a hydrogen-based membrane palladium-film reactor (MPfR) by depositing palladium nanoparticles (PdNPs) on hollow-fiber membranes via autocatalytic hydrogenation to form a Pd-film. The MPfR was used for hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP). HDC performances and mechanisms were systematically evaluated, and a continuous-flow dechlorination model was established. Approximately 87% of the input 2,4-DCP was reduced to the end-product phenol (P), while 2-chlorophenol (2-CP) was an intermediate, but only at 2%. Selective adsorption of the 2,4-DCP onto the Pd-film and fast desorption of P facilitated efficient dechlorination. Modeling results represented well the concentrations of 2,4-DCP and its intermediates. It demonstrated three dechlorination pathways: The majority of 2,4-DCP was completely dechlorinated to P in an adsorbed state without release of monochlorphenol, some 2,4-DCP was degraded to 2-CP that was released and subsequently adsorbed and reduced to P, and a small amount was reduced to 4-CP that was released and subsequently adsorbed and reduced to P. Analysis based on Density Functional Theory suggests that the pathway of full dechlorination was dominant due to its thermodynamically favorable adsorption configuration, with both Cl atoms bonded to Pd. This study documents full dechlorination of 2,4-DCP in the MPfR and the interacting roles of adsorption and HDC.

Stereoselective metabolism and potential adverse effects of chiral fungicide triadimenol on Eremias argus

Reptiles are an important part of vertebrates and are the primitive terrestrial vertebrates. However, lots of reptile species are endangered or susceptible to extinction. It is no doubt that contaminants are one of the important reasons for the decline of the lizard population. In this study, the selective metabolism of triadimenol (TN) in the male Eremias argus lizards and the toxic effects of TN on lizards were studied. TN chiral isomers were separated and detected by HPLC-MS/MS system with Lux Cellulose-1 column. Tissue distribution experiments showed the existence of stereoselectivity biotransformation of TN enantiomers among organs in lizards, and RR-TN preferentially emerged over the other enantiomers. The antioxidant enzymes (SOD, CAT, GST) activities and MDA content assays demonstrated that TN induced oxidative stress in most organs, especially in the liver, and the histopathology analysis showed the severe liver and testis damage caused by 14-day continuous TN gavage. The reproductive effects of TN-induced reflected in the increased sex hormone testosterone. This research confirms that TN could induce hepatic and reproductive toxicity of E. argus lizard.

Therapeutic effect of N- acetyl cysteine as an antioxidant on rainbow trout's brain in cypermethrin toxicity

The aim of this study was to investigate the therapeutic effect of N-acetylcystein (NAC) against oxidative stress induced by Cypermethrin pesticide in rainbow trout (Oncorhynchus mykiss). The experiment was designed as 5 groups (A, B, C, D, and E). Group A was organized as control group and had no treatment. The other groups were treated with Cypermethrin for 14 days. At the end of this period, Groups B (1.0 mM NAC) and D (0.5 mM NAC) was performed with NAC for 96 h. Group C was not administered NAC, the recovery process was evaluated with this group. Group E was exposed to cypermethrin during 14 days and sampled. Acetylcholinesterase (AChE), malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO) activities, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG)), caspase-3 levels, and trace elements contents analyses were performed in all fish brains. According to the results, MDA, MPO, 8-OHdG and caspase-3 levels were significantly decreased compared to the other groups (pesticide and recovery) (p < 0.05), AChE, SOD, CAT, GPx, PON, and AR activities increased (p < 0.05). In brain tissue, no statistically significant difference was observed in trace element analysis of all application groups. According to the obtained data, the positive effect of N-acetylcysteine on protein synthesis, detoxification, and diverse metabolic functions against cypermethrin toxicity has been more effective in 1.0 mM NAC. NAC has important therapeutic effect on pesticide-induced neurotoxicity for fish in terms of all data. It was concluded that NAC has an antioxidant effect against pesticide-induced oxidative stress and the selected biochemical markers are useful for such studies.

2,4-Dichlorophenol induces DNA damage through ROS accumulation and GSH depletion in goldfish Carassius auratus

2,4-Dichlorophenol (2,4-DCP) is one of the most abundant chlorophenols in the aquatic environment and has been frequently detected in surface waters. Although ecological and cellular toxicity of 2,4-DCP has aroused the public concern, few reports focus on the genotoxicity, especially on DNA double strand breaks (DSBs), of 2,4-DCP in fish. The present study aims to explore the genotoxic effect of 2,4-DCP on DSBs in goldfish Carassius auratus and to further elucidate its potential mechanism. The results showed that 2,4-DCP significantly induced DSBs (detected by neutral comet assay) in erythrocytes and hepatocytes of goldfish in a dose-dependent manner, indicating a genotoxicity of 2,4-DCP on fish. The total antioxidant capability and the content of reduced glutathione (GSH) were significantly decreased, while the level of reactive oxygen species (ROS) was significantly increased in a dose-dependent manner in erythrocytes and hepatocytes, suggesting an oxidative stress caused by 2,4-DCP in fish. N-acetyl-l-cysteine, a precursor of GSH and a ROS scavenger, significantly impaired 2,4-DCP-induced ROS overproduction and DSBs, which proves that ROS accumulation and GSH depletion are involved in 2,4-DCP-induced DNA damage in fish. Environ. Mol. Mutagen. 59:798-9, 2018. © 2018 Wiley Periodicals, Inc.

Influence of nano-zinc oxide on tropane alkaloid production, h6h gene transcription and antioxidant enzyme activity in Hyoscyamus reticulatus L. hairy roots

The use of nanotechnology and biotechnology to improve the production of plant bioactive compounds is growing. Hyoscyamus reticulatus L. is a major source of tropane alkaloids with a wide therapeutic use, including treatment of Parkinson's disease and to calm schizoid patients. In the present study, hairy roots were obtained from two-week-old cotyledon explants of H. reticulatus L. using the A7 strain of Agrobacterium rhizogenes. The effects of different concentrations of the signaling molecule nano-zinc oxide (ZnO) (0, 50, 100 and 200 mg/L), with three exposure times (24, 48 and 72 h), on the growth rate, antioxidant enzyme activity, total phenol contents (TPC), tropane alkaloid contents and hyoscyamine-6-beta-hydroxylase (h6h) gene expression levels were investigated. Growth curve analysis revealed a decrease in fresh and dry weight of ZnO-treated hairy roots compared to the control. ANOVA results showed that the antioxidant activity of the enzymes catalase, guaiacol peroxidase and ascorbate peroxidase was significantly higher in the ZnO-treated hairy roots than in the control, as was the TPC. The highest levels of hyoscyamine (37%) and scopolamine (37.63%) were obtained in hairy roots treated with 100 mg/L of ZnO after 48 and 72 h, respectively. Semi-quantitative RT-PCR analysis revealed the highest h6h gene expression was in hairy roots treated with 100 mg/L of ZnO after 24 h. It can be concluded that ZnO is as an effective elicitor of tropane alkaloids such as hyoscyamine and scopolamine due to its enhancing effect on expression levels of the biosynthetic h6h gene.

Pesticide toxicity: a mechanistic approach

Pesticides are known for their high persistence and pervasiveness in the environment, and along with products of their biotransformation, they may remain in and interact with the environment and living organisms in multiple ways, according to their nature and chemical structure, dose and targets. In this review, the classifications of pesticides based on their nature, use, physical state, pathophysiological effects, and sources are discussed. The effects of these xenobiotics on the environment, their biotransformation in terms of bioaccumulation are highlighted with special focus on the molecular mechanisms deciphered to date. Basing on targeted organisms, most pesticides are classified as herbicides, fungicides, and insecticides. Herbicides are known as growth regulators, seedling growth inhibitors, photosynthesis inhibitors, inhibitors of amino acid and lipid biosynthesis, cell membrane disrupters, and pigment biosynthesis inhibitors, whereas fungicides include inhibitors of ergosterol biosynthesis, protein biosynthesis, and mitochondrial respiration. Insecticides mainly affect nerves and muscle, growth and development, and energy production. Studying the impact of pesticides and other related chemicals is of great interest to animal and human health risk assessment processes since potentially everyone can be exposed to these compounds which may cause many diseases, including metabolic syndrome, malnutrition, atherosclerosis, inflammation, pathogen invasion, nerve injury, and susceptibility to infectious diseases. Future studies should be directed to investigate influence of long term effects of low pesticide doses and to minimize or eliminate influence of pesticides on non-target living organisms, produce more specific pesticides and using modern technologies to decrease contamination of food and other goods by pesticides.

Liver histopathology and biochemical biomarkers in Gobius niger and Zosterisessor ophiocephalus from polluted and non-polluted Tunisian lagoons (Southern Mediterranean Sea)

The aim of this study was to appraise the response of a multi-marker approach in fish species, Gobius niger and Zosterisessor ophiocephalus, in a polluted lagoon (Bizerte lagoon: MB and ML sites) and in a reference site (Ghar-El-Melh lagoon entrance) by the analysis of physiological indexes, liver histopathology and some biochemical biomarkers. The results showed liver hypertrophy in fish collected from Bizerte lagoon as well as many non-specific lesions, unlike the reference site. All Bizerte lagoon sites had the same prevalence of histopathological lesions, but the mean intensity (MI) of parasites seemed to be more sensible as an indicator of pollution levels. Indeed, parasite MI was more important in MB site that has a higher pollution level. Also, biochemical biomarkers showed an induction in Bizerte lagoon sites with some differences within sites and species. The impact of the continuous release of pollution on the biomarker's response is discussed.

Triclosan removal from surface water by ozonation - Kinetics and by-products formation

Removal of triclosan from surface water by ozonation was investigated. The results showed that complete elimination of triclosan from a surface water bearing 1-5 mg/L triclosan via continuous ozonation at 5 mg/L, require an ozonation time of 20-30 min depending on pH. Triclosan oxidation followed pseudo-first order kinetics with an apparent reaction rate constant varying from 0.214 min^-1 to 0.964 min^-1 depending on pH, initial triclosan concentration and water composition. Although the effect of pH was complex due to possible existence of different moieties, higher TCS removal efficiencies were obvious at weak-base conditions. Experiments performed to identify degradation by-products showed the formation of four by-products, namely, 2,4-dichlorophenol, 4-chlorocatechol and two unidentified compounds. Additionally, 2,4-dichloroanisole was detected when a methyl moieties exist in water. By-products were found to be eliminated upon further ozonation. The required exposure time varied from 20 to 30 min depending on pH of water. The ozone demand exerted for the complete oxidation of triclosan and its by-products was calculated as 13.04 mg ozone per mg of triclosan. A triclosan degradation pathway, which was found to be highly pH dependent, was proposed.

Antioxidant Response in Duckweed After Exposure to Secondary Effluent from Municipal Wastewater Treatment Plant, Elazığ, Turkey

The aim of this study is to evaluate the effects of the effluent of Elazig Municipality Wastewater Treatment Plant on the oxidative defense capacity of aquatic plants (Lemna minor L. and Lemna gibba L.). For this purpose, malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), vitamin A (retinol), vitamin E (α-tocopherol), and vitamin C (Ascorbic acid) levels were determined by the HPLC (high performance liquid chromatography) in the control groups and the groups adapting to reactors fed with discharge water. The depletion of vitamins (A, E, and C), decrease of GSH/GSSG ratio, and increase of MDA that reflect a precarious state of the cell in L. minor L. and L. gibba L. were observed after exposure to wastewater. It can be suggested that the selected biomarkers are useful in understanding the biochemical mechanisms of the secondary effluents from wastewater treatment plant in L. minor L. and L. gibba L. as early warning indicators.

Bioconcentration and multi-biomarkers of organic UV filters (BM-DBM and OD-PABA) in crucian carp

Organic UV filters (OUV-Fs) are increasingly used in sunscreens and personal care products. In the present work, the bioconcentration and multi-biomarker effects of butyl methoxydibenzoylmethane (BM-DBM) and ethylhexyl dimethyl p-aminobenzoate (OD-PABA) were investigated in crucian carp (Carassius auratus). The fish were exposed to various concentrations of BM-DBM (3.88, 35.61, 181.85 and 337.15μg/L), OD-PABA (4.66, 53.83, 264.22 and 459.32μg/L) and their mixture (2.31+2.79, 23.69+26.18, 97.37+134.81 and 193.93+246.08μg/L) for 28 days. The maximal concentrations of two OUV-Fs were detected in the fish liver, followed by the brain, kidney, gill and muscle in most cases. The maximal BCF values of OD-PABA calculated in various exposure concentrations were 0.37 - 101.21 in single exposure groups and 0.11 - 31.09 in mixed exposure groups. Acetylcholinesterase (AChE) activity was significantly inhibited by BM-DBM as well as the mixtures at all of the exposure concentrations and by OD-PABA at higher concentrations (≥264.22μg/L) during 28 days of exposure. The maximal inhibition rates of AChE activity reached 64.04% for BM-DBM, 41.05% for OD-PABA and 61.50% for the mixtures at the highest concentration, which indicated that these two OUV-Fs might damage the central nervous system. Concerning oxidative stress status, BM-DBM and the mixtures significantly increased superoxide dismutase (SOD) and glutathione reductase (GR) activities and inhibited catalase (CAT) activity, while OD-PABA caused a significant increase of GR and CAT activities. AChE and GR activities seemed to be more sensitive biomarkers for BM-DBM and OD-PABA.

Single and combined effects of aluminum (Al2O3) and zinc (ZnO) oxide nanoparticles in a freshwater fish, Carassius auratus

The increasing use of nanoparticles (NPs) worldwide has raised some concerns about their impact on the environment. The aim of the study was to assess the toxicity of metal oxide nanoparticles, singly or combined, in a freshwater fish (Carassius auratus). The fish were exposed for 7, 14, and 21 days to different concentrations of NPs (10 μg Al₂O₃.L^-1, 10 μg ZnO.L^-1, 10 μg Al₂O₃.L^-1 plus 10 μg ZnO.L^-1, 100 μg Al₂O₃.L^-1, 100 μg ZnO.L^-1, and 100 μg Al₂O₃.L^-1 plus 100 μg ZnO.L^-1). At the end of each exposure period, antioxidant enzyme activity (catalase, glutathione-S-transferase, and superoxide dismutase), lipid peroxidation, and histopathology were assessed in the gills and livers of C. auratus. The results show an increase in catalase (CAT) and superoxide dismutase (SOD) activity in the gills and livers of fish, especially after 14 days of exposure to single and combined NPs, followed by a reduction at 21 days. An increase in glutathione S-transferase (GST) was observed in gills after 7 days for all tested NP concentrations (single and combined); while in livers, a significant increase was determined after 14 days of exposure to 100 μg.L^-1 of both single ZnO and Al₂O₃ NPs. Lipid peroxidation (LPO) significantly increased in gills after 7 days of exposure to 100 μg.L^-1 Al₂O₃ NPs (single or combined). In livers, LPO increased significantly after 7 days of exposure to all tested concentrations of both single ZnO and Al₂O₃ (except for 10 μg Al₂O₃.L^-1), and after 14 days of exposure to ZnO (10 and 100 μg.L^-1) and Al₂O₃ (100 μg.L^-1)_. The results from histological observations suggest that exposure to metal oxide NPs affected both livers and gills, presenting alterations such as gill hyperplasia and liver degeneration. However, the most pronounced effects were found in gills. In general, this study shows that the tested NPs, single or combined, are capable of causing sub-lethal effects on C. auratus, but when combined, NPs seem to be slightly more toxic than when added alone.

The oxidative stress in the liver of Carassius auratus exposed to acesulfame and its UV irradiance products

Acesulfame (ACE) is listed as an emerging contaminant due to its environmental persistence and wide occurrence in the environment. ACE can be degraded partially in the regular UV disinfection process but the eco-toxicity of its irradiation products remains unclear. This study focused on the possible oxidative status change in the liver of Carassius auratus exposed to ACE and its irradiation products. The UV degradation of ACE follows pseudo-first-order kinetics, and eight irradiation products were identified. Fish were exposed 7days to 0.1 and 10mg/L ACE (ACE group) and ACE after UV irradiance (ACE-UV group). The oxidative stress in fish liver exposed to ACE group had no distinct change. However, in the ACE-UV group, the quantity of OH was induced by 17.96-55% and the MDA content increased by 16.28-68.28% compared to control. Time-effect exposure in the ACE-UV group showed that in the first 3days the quantity of OH reached its peak, causing severe inhibition of SOD and continuous inducement of GPx. GSH helped scavenge OH and decreased below control after 3days. An increased toxicity of ACE after UV irradiance was observed and its transfer after into aquatic environment needs to be recognized as an environmental risk.

Combination effects of nano-TiO2 and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on biotransformation gene expression in the liver of European sea bass Dicentrarchus labrax

The aim of present study was to investigate the influence of titanium dioxide nanoparticles (nano-TiO2, Aeroxide® P25) on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dependent biotransformation gene expression in liver of juvenile European sea bass Dicentrarchus labrax. An in vivo 7day waterborne exposure was performed with nano-TiO2 (1mg/L) and 2,3,7,8-TCDD (46pg/L), singly and in combination. The mRNA expression of aryl hydrocarbon receptor repressor (Ahrr), estrogen receptor (erβ2), ABC transport proteins as Abcb1, Abcc1-c2-g2, cytochrome P450 (cyp1a), glutathione-s-transferase (gsta), glutathione reductase (gr) and engulfment and motility (ELMO) domain-containing protein 2 (elmod2) was investigated. Ahrr, erβ2, abcc1 and abcg2 resulted down-regulated with respect to controls in all experimental groups. Co-exposure to nano-TiO2 and 2,3,7,8-TCDD caused a further significant down regulation of ahrr, erβ2, Abcb1 and Abcc2 compared to single chemical exposure (nano-TiO2 or 2,3,7,8-TCDD alone). No effects were observed for 2,3,7,8-TCDD and nano-TiO2 alone in abcb1 gene, while abcc2 was down-regulated by nano-TiO2 alone. Cyp1a, gst and elmod2 genes were up-regulated by 2,3,7,8-TCDD and to a similar extent after co-exposure. Overall the results indicate that nano-TiO2 is unlikely to interfere with 2,3,7,8-TCDD-dependent biotransformation gene expression in the liver of European sea bass, although the effects of co-exposure observed in ABC transport mRNAs might suggest an impact on xenobiotic metabolite disposition and transport in European sea bass liver.

Toxicological effects and oxidative stress responses in freshwater snail, Lanistes carinatus, following exposure to chlorpyrifos

Chlorpyrifos is a widely used organophosphorous pesticide in agriculture and environmental health. Laboratory studies of chlorpyrifos have revealed acute lethal toxicity at very low concentration (96-h LC50) of 0.39 μg L(-1) to the freshwater snail, Lanistes carinatus. Acetylcholinesterase (AChE) inhibition progressed and reached 52% and 78% of the control after 28-d exposure to 0.09 and 0.29 μg L(-1) chlorpyrifos, respectively. Catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities increased in comparison to control group in the first period of exposure (7-21 d), then decreased relative to the control in the second period of exposure (21-28 d). A significant (p<0.05) glutathione (GSH) depletion was observed in snails exposed to 0.09 and 0.29 μg L(-1) in comparison to the control, whereas malondialdehyde (MDA) content gradually increased in a dose-dependent manner. This study showed that alterations in antioxidant enzyme activities along with depletion of GSH content and elevation of MDA content can be used as biomarkers in environmental assessment programs.

The effects of Juglans regia L. (walnut) extract on certain biochemical paramaters and in the prevention of tissue damage in brain, kidney, and liver in CCl4 applied Wistar rats

Objective: The purpose of this study is to demonstrate protective effects of walnut samples on CCl

Methods: Walnut fruits were extracted and then subjected to vitamin and flavonoid analyses. The extracts obtained were injected intraperitoneally every other day to Wistar male rats given carbon tetrachloride (CCl

Results: Given the results achieved, it was found that the levels of fatty acids increased in the brain and kidney tissues after CCl

Conclusion: Our data indicates that walnut extract has protective effects against LPO formation in the brain, kidney and liver tissues.

Effect of sodium dodecyl sulfate (SDS) on stress response in the Mediterranean mussel (Mytilus Galloprovincialis): regulatory volume decrease (Rvd) and modulation of biochemical markers related to oxidative stress

In this study the effects of an anionic surfactant, sodium dodecyl sulfate (SDS), are assessed on the Mediterranean mussel (Mytilus galloprovincialis), exposed for 18 days at a concentration ranging from 0.1 mg/l to 1 mg/l. The effects are monitored using biomarkers related to stress response, such as regulatory volume decrease (RVD), and to oxidative stress, such as reactive oxygen species (ROS), endogenous antioxidant systems and Hsp70 levels. The results demonstrate that cells from the digestive gland of M. galloprovincialis, exposed to SDS were not able to perform the RVD owing to osmotic stress. Further, SDS causes oxidative stress in treated organisms, as demonstrated by the increased ROS production, in comparison to the controls (p<0.05). Consequently, two enzymes involved in ROS scavenging, superoxide dismutase (SOD) and catalase (CAT) have higher activities and the proportion of oxidized glutathione (GSSG) is higher in hepatopancreas and mantle of treated animals, compared to untreated animals (p<0.05). Furthermore Hsp70 demonstrates an up-regulation in all the analyzed tissues of exposed animals, attesting the stress status induced by the surfactant with respect to the unexposed animals. The results highlight that SDS, under the tested concentrations, exerts a toxic effect in mussels in which the disruption of the osmotic balance follows the induction of oxidative stress.

Stereoselective degradation and toxic effects of benalaxyl on blood and liver of the Chinese lizard Eremias argus

Benalaxyl as a xylem-systemic fungicide is usually direct sprayed on the soil surface, which is potential harm to the animals lived in the soil. However, the stereoselectivity of benalaxyl in reptiles have rarely been studied. In this study, Chinese lizards (Eremias argus) were firstly used to evaluate the stereoselectivity in biodegradation and toxicity of racemate and individual enantiomers of benalaxyl. A method for determining residues of the two enantiomers of benalaxyl in lizard blood and liver by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-MS/MS) was developed. The degradation followed pseudo first-order kinetics and the degradation of the (S)-(+)-benalaxyl was faster than its antipode in blood and liver (Half-time t1/2 of (R)-(-)-benalaxyl and (S)-(+)-benalaxyl were 5.08 h and 3.75 h in blood, 6.21 h and 4.45 h in liver, separately). Moreover, antioxidant defenses consisting of activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and lipid peroxide malondialdehyde (MDA) were determined in 24h acute exposure. Enantioselectivity of acute toxicity depended on the concentration and form of benalaxyl. In addition, cellular degeneration, decrease of cell number, clustering phenomena of cell nuclei and preliminary liver fibrosis were observed in pathological detection at the termination of 21-d subchronic exposure (20 mg/kg(-bw) of racemate and individual enantiomers of benalaxyl). The enantiomer fractions (EFs) in racemate and individual enantiomer groups were approached both in blood and liver caused by the chiral conversion. The chiral conversion from (R)-(-)-benalaxyl to (S)-(+)-benalaxyl and (S)-(+)-benalaxyl to (R)-(-)-benalaxyl were the primary cause for no remarkable differences in toxicity between the enantiomers of benalaxyl.

Liver alterations in two freshwater fish species (Carassius auratus and Danio rerio) following exposure to different TiO₂ nanoparticle concentrations

The toxicity of titanium dioxide nanoparticles (TIO₂ NPs) and oxidative stress effects were studied in two freshwater fish species (Carassius auratus and Danio rerio) exposed for 21 days to different concentrations (0.01, 0.1, 1, 10, 100/mgL) of TiO₂ NPs and to a control (tap water). Additional fish were transferred to clean water for 14 days to assess the ability to recover from exposure to TiO₂ NPs. Activities of the enzyme glutathione-S-transferase (GST) and lipid peroxidation (LPO) (malondialdheyde) were measured as indicators of oxidative stress. Histological and ultra-structural changes in livers from both species of fish were evaluated by light and electron microscopy. Results show a general GST activity increase according to TiO₂ NPs concentrations, which is in agreement with data from LPO. After 21 days, GST activities decreased possibly caused by suppression of GST synthesis as a result of severe stress. Histological and ultra-structural analysis of livers from exposed fish show degeneration of the hepatic tissue and alterations in hepatocytes such as glycogen depletion and an increase in lipofucsin lysosome-like granules. After a depuration period a partial recovery for biochemical markers and cells was observed. The results suggest that TiO₂ promotes alterations in hepatic tissues compatible with oxidative stress.

Responses of oxidative stress biomarkers and DNA damage on a freshwater snail (Bellamya aeruginosa) stressed by ethylbenzene

Ethylbenzene is classified as a priority pollutant; however, toxicity data, especially those regarding sublethal toxicity, are rarely reported on gastropods. The present work was performed to elucidate the sublethal effects of ethylbenzene using a freshwater snail, Bellamya aeruginosa (Reeve), exposed to ethylbenzene for 21 days followed by a 17-day recovery period. Superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), reduced glutathione (GSH), and malonyldialdehyde (MDA) were used as biomarkers to evaluate oxidative stress in hepatopancreas of snails. In addition, alkaline comet assay was applied to determine the genotoxicity of ethylbenzene in hepatopancreas of snails. These biomarkers and DNA damage exhibited various responses to ethylbenzene in the tested snails. SOD and CAT activities were almost significantly stimulated during the exposure period. As exposure time was prolonged beyond 7 days, CAT activity gradually became significantly increased at higher doses of ethylbenzene. GSH concentration was positively and linearly related with exposure dose. MDA concentration was significantly greater than that in the control only under the lowest treatment after a 7-day exposure. Alkaline comet assay showed that ethylbenzene could significantly induce DNA damage in hepatopancreas of snails, and there was a good dose- and time-response in DNA damage, indicating potential genotoxicity of ethylbenzene on snails. At the end of the recovery period, the repair of DNA damage was not yet completed, showing that DNA repair requires more time. The findings from this study could indicate that SOD, GST, and GSH seem to be effective oxidative biomarkers for snails exposed to ethylbenzene in the short term. CAT proved to be a valuable discriminating biomarker in subchronic exposure to ethylbenzene, but MDA was not a suitable oxidative biomarker for exposure to ethylbenzene in either the short or long term. Alkaline comet assay was efficient tool with which to evaluate the potential genotoxicity of ethylbenzene.

A high activity of Ti/SnO2-Sb electrode in the electrochemical degradation of 2,4-dichlorophenol in aqueous solution

Electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Ti/SnO2-Sb anode. The factors influencing the degradation rate, such as applied current density (2-40 mA/cm2), pH (3-11) and initial concentration (5-200 mg/L) were evaluated. The degradation of 2,4-DCP followed apparent pseudo first-order kinetics. The degradation ratio on Ti/SnO2-Sb anode attained > 99.9% after 20 min of electrolysis at initial 5-200 mg/L concentrations at a constant current density of 30 mA/cm2 with a 10 mmol/L sodium sulphate (Na2SO4) supporting electrolyte solution. The results showed that 2,4-DCP (100 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9% and 92.8%, respectively, at the optimal conditions after 30 min electrolysis. Under this condition, the degradation rate constant (k) and the degradation half-life (t1/2) were 0.21 min- and (2.8 +/- 0.2) min, respectively. Mainly carboxylic acids (propanoic acid, maleic acid, propanedioic acid, acetic acid and oxalic acid) were detected as intermediates. The energy efficiencies for 2,4-DCP degradation (5-200 mg/L) with Ti/SnO2-Sb anode ranged from 0.672 to 1.602 g/kWh. The Ti/SnO2-Sb anode with a high activity to rapid organic oxidation could be employed to degrade chlorophenols, particularly 2,4-DCP in wastewater.

Glutathione and its dependent enzymes' modulatory responses to toxic metals and metalloids in fish--a review

Toxic metals and metalloid are being rapidly added from multiple pathways to aquatic ecosystem and causing severe threats to inhabiting fauna including fish. Being common in all the type of aquatic ecosystems such as freshwater, marine and brackish water fish are the first to get prone to toxic metals and metalloids. In addition to a number of physiological/biochemical alterations, toxic metals and metalloids cause enhanced generation of varied reactive oxygen species (ROS) ultimately leading to a situation called oxidative stress. However, as an important component of antioxidant defence system in fish, the tripeptide glutathione (GSH) directly or indirectly regulates the scavenging of ROS and their reaction products. Additionally, several other GSH-associated enzymes such as GSH reductase (GR, EC 1.6.4.2), GSH peroxidase (EC 1.11.1.9), and GSH sulfotransferase (glutathione-S-transferase (GST), EC 2.5.1.18) cumulatively protect fish against ROS and their reaction products accrued anomalies under toxic metals and metalloids stress conditions. The current review highlights recent research findings on the modulation of GSH, its redox couple (reduced glutathione/oxidised glutathione), and other GSH-related enzymes (GR, glutathione peroxidase, GST) involved in the detoxification of harmful ROS and their reaction products in toxic metals and metalloids-exposed fish.

Oxidative stress response in atrazine-degrading bacteria exposed to atrazine

Rhodobacter sphaeroides W16 and Acinetobacter lwoffii DNS32 which were isolated from soil in cold area subjected to a long-term atrazine application in Heilongjiang Province (China) can degrade atrazine efficiently. The investigation of their antioxidant properties will be useful for bioremediation and engineering applications of atrazine-degrading bacteria. Superoxide dismutase (SOD) and catalase (CAT) from two atrazine-degrading bacteria and one non-atrazine-degrading bacterium were tested for response to the oxidative stress caused by atrazine. Atrazine produced a greater inhibition of growth in Bacillus subtilis B19. The three bacteria apparently produced two activity peaks of SOD and CAT. The results demonstrated all three bacteria possessed a mechanism for atrazine tolerance that may include controlling the cellular redox balance by producing reactive oxygen species (ROS) and the subsequent scavenging of the ROS, but such response was more rapid and at lower levels in the two atrazine-degrading bacteria, suggesting less oxidative damage in these cells upon atrazine exposure. Compared to B. subtilis B19, atrazine-degrading bacteria had relatively high tolerance to atrazine stress, especially R. sphaeroides W16. Therefore, R. sphaeroides W16 and A. lwoffii DNS32 have a good application prospect of bioremediation project for soil contaminated by atrazine in cold area in Heilongjiang Province.

Oxidative stress response in two representative bacteria exposed to atrazine

Bacteria are present extensively in the environment. Investigation of their antioxidant properties will be useful for further study on atrazine stress tolerance of bacteria and the defense mechanism of antioxidant enzymes against atrazine or other triazine herbicides. Superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and total antioxidant capacity (T-AOC) from one Gram-negative representative strain Escherichia coli K12 and one Gram-positive representative strain Bacillus subtilis B19, respectively, were tested for response to atrazine stress. The results indicated that SOD, CAT, GST and T-AOC were induced upon exposure to atrazine. The growth of two bacteria was better in the absence than in the presence of atrazine, indicating that atrazine can decrease bacterial growth. The changes of enzyme activities indicate the presence of oxidative stress. Oxidative stress induced by atrazine may be due to imbalance of redox potential in bacterial cells, which leads to bacterial metabolic disorder.

Lipid peroxidation and antioxidant defense enzymes in Clarias gariepinus as useful biomarkers for monitoring exposure to polycyclic aromatic hydrocarbons

The toxicological evaluations of crude oil, xylene, toluene and benzene were carried out against juvenile stages of Clarias gariepinus. On the basis of LC(50) value, benzene (0.017 ml/l) was found to be the most toxic followed by xylene (0.086 ml/l), toluene (0.398 ml/l) and crude oil (2.219 ml/l) was the least toxic. The results of the lipid peroxidation assay showed that the level of malonaldehyde (MDA) in liver and gills of fish exposed to all the test chemicals increased significantly (P < 0.05) when compared to control. Measurement of activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) in liver and gill of fishes exposed to sublethal concentration of the test chemicals over a 28-day period was found to decrease significantly (P < 0.05) when compared to control. The observed reduction in the activities of antioxidant defense enzymes such as SOD, CAT and GST in conjunction with an increase in MDA levels in the gill and liver tissues of test animals exposed to aromatic hydrocarbon compounds were recommended as a good battery of biomarkers for early detection of pollution during biomonitoring programmes.

Oxidation of 2,4-dichlorophenol and 3,4-dichlorophenol by means of Fe(III)-homogeneous photocatalysis and algal toxicity assessment of the treated solutions

Chlorophenols are used worldwide as broad-spectrum biocides and fungicides. They have half-life times in water from 0.6 to 550 h and in sediments up to 1700 h and, due to their numerous origins, they can be found in wastewaters, groundwaters or soils. Moreover, chlorophenols are not readily biodegradable. Recently, classic Advanced Oxidation Processes (AOP) have been proposed for their abatement in an aqueous solution. This paper investigates the oxidation of 2,4-dichlorophenol and 3,4-dichlorophenol, at starting concentrations of 6.1 · 10(-5) mol L(-1), in aqueous solutions through Fe(III)/O(2) homogeneous photocatalysis under UV light (303 ÷ 366 nm). The Fe(III)/O(2) homogeneous photocatalysis is less expensive than using H(2)O(2) due to the capability of Fe(III) to produce OH radicals, if irradiated with an UVA radiation, and of oxygen to re-oxidize ferrous ions to ferric ones when dissolved in solution. The results show that the best working conditions, for both compounds, are found for pH=3.0 and initial Fe(III) concentration equal to 1.5 · 10(-4) mol L(-1) although the investigated oxidizing system can be used even at pH close to 4.0 but with slower abatement kinetics. Toxicity assessment on algae indicates that treated solutions of 2,4-dichlorophenol are less toxic on algae Pseudokirchneriella subcapitata if compared to not treated solutions whereas in the case of 3,4-dichlorophenol only the samples collected during the runs at 20 and 60 min are capable of inhibiting the growth of the adopted organism. The values of the kinetic constant for the photochemical re-oxidation of iron (II) to iron (III) and for HO attack to intermediates are evaluated by a mathematical model for pH range of 2.0-3.0 and initial Fe(III) concentrations range of 1.5 · 10(-5)-5.2 · 10(-4) mol L(-1).

Effects of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate on the Mytilus galloprovincialis biomarker system

The effects of in vivo exposure of Mytilus galloprovincialis to two anionic surfactants (SDBS and SDS) on the molecular biomarker system were studied. After continuous exposure for 72 days, activities/levels of GST, GPx and GSH were significantly higher than in corresponding control groups following exposure to 3.000 mg/L SDS and SDBS. Activities of SOD and CAT were significantly inhibited by experimental SDBS (except CAT in 0.100mg/L group), but not by SDS. Statistical analysis of enzyme activities/levels suggested that there were significant positive relationships between GST and GPx, and negative relationships were found between GSH and CAT, GSH and SOD. Amplified fragment length polymorphism (AFLP) results showed that a greater genotoxic effect was observed for SDBS than for SDS. Based on the above results, the biomarker system of mussels can be affected by the two anionic surfactants (>or=3.000 mg/L); it was more easily affected by SDBS than by SDS.

Oxidative stress and histopathology damage related to the metabolism of dodecylbenzene sulfonate in Senegalese sole

Surfactants such as linear alkylbenzene sulfonates (LAS) are widely utilised in the formulation of detergents in commercial products. After use, they pass through waste water treatment plants (WWTP) and are then discharged to aquatic ecosystems, causing risk to aquatic life. The exposure of marine animals to these compounds enhances the production of reactive oxygen species (ROS) with subsequent damage to macromolecules, and produces histological alterations. A flow-through experiment with Senegalese sole (Solea senegalensis) has been devised with the object of correlating the metabolism of LAS including sulfophenylcarboxylic acids (SPCs) by fish with their antioxidant defence system (generation of oxyradicals) and histopathological damage. The generation of intermediate degradation products (SPCs) by the organism, the histopathological responses, the antioxidant enzymes (catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione S-transferase (GST)), as well as other kinds of enzyme such as acid and alkaline phosphatases (AcP, ALP), were measured. SPCs from 5ØC(6) to 11ØC(12) were identified and quantified in fish and water; their concentrations differed depending on the sampling moment. In general, the responses found in the enzymes were slight: a decrease in the enzymatic activity in gills and activation in the digestive tract. The evidence of histopathological damage identified was also small; the organism's defensive mechanism against pollutants should enable it to recover easily. A direct relationship was established between biotransformation and the generation of SPCs and ROS. In conclusion, the correct functioning of the antioxidant defence system with absence of large variations, the short-term histopathological damage, and the evidence of SPCs indicate an adequate metabolism of 2-phenyl-C(12)-linear alkylbenzene sulfonates (2ØC(12)LAS) by this specie and non-toxic effects at environmentally realistic levels.

Toxic effects of chlorpromazine on Carassius auratus and its oxidative stress

Under laboratory conditions, ecotoxicological effects of chlorpromazine (CPZ) on freshwater goldfish (Carassius auratus) were examined using the toxic culture experiment. The results showed that the median lethal concentration (LC(50)) of CPZ toxic to Carassius auratus in 24, 48 and 96 h was 1.11, 0.43 and 0.32 mg/L, respectively. Thus, CPZ is an extreme toxicant to goldfish. Furthermore, there were significantly positive correlations between the ecotoxicological effects of CPZ and its concentrations, and the toxicity became higher as the exposure time increased. The activity of superoxide dismutase (SOD) and catalase (CAT) in goldfish livers was significantly influenced by CPZ. At the same exposure time, the activity of SOD reduced first, and increased then, whereas the activity of CAT enhanced first and decreased then. At the same exposure levels of CPZ, the activity of SOD and CAT changed similarly, decreased first, then increased and decreased at last. Within the range of exposure concentrations, the changes in the activity of CAT can more easily reflect the oxidation stress in Carassius auratus by CPZ than those of SOD.

In vivo effects of fenthion on oxidative processes by the modulation of glutathione metabolism in the brain of Oreochromis niloticus

The present study was designed to understand the oxidative stress potential of fenthion, an organophosphate (OP) pesticide and its involvement in glutathione metabolism modulated buthionine sulfoximine (BSO, 50 mg/kg) and N-acetylcysteine (NAC, 100 mg/kg) in the brain of fish, Oreochromis niloticus. A sublethal fenthion concentration (0.45 mg/L) was applied for 24, 48, and 96 h together with injection with BSO or NAC; following treatment, recovery periods for 24, 48, and 96 h were allowed. Total glutathione (tGSH), oxidized glutathione (GSSG), lipid peroxidation, protein level, and GSH-related enzyme activities were analyzed by using spectrophotometric methods. Fenthion in applied concentration did not change GSH levels, but increased GSSG levels. BSO application in fenthion exposure caused a depletion in GSH, while increasing the GSSG levels. Glutathione peroxidase (GPx; EC 1.11.1.9) specific activity increased in fenthion-applied groups at 24-h treatment. gamma-Glutamylcysteinyl synthetase (gamma-GCS; EC 6.3.2.2) was not detected in the brain. NAC injection in fenthion treatment decreased GSH and increased GSSG levels and GST activity. In conclusion, fenthion in sublethal concentration induced an oxidative stress processes in brain. BSO application provided an evidence for the involvement of fenthion in GSH metabolism. NAC elevated the fenthion-induced effects in spite of its antioxidant properties. Recovery period for 96 h was not adequate to eliminate the fenthion-induced changes.

Effects of acute and subchronic exposures to waterborne selenite on the physiological stress response and oxidative stress indicators in juvenile rainbow trout

Selenium (Se) is an essential element that may bioaccumulate to toxic levels. In fish, the major toxicity symptom is larval teratogenic deformities, but little is known about the effect of Se on other systems such as the physiological stress response and oxidative stress. To test the hypothesis that Se is a chemical stressor that causes toxicity through oxidative stress, juvenile rainbow trout were exposed to waterborne sodium selenite, and physiological stress response and stress-related parameters (plasma cortisol, glucose, T3 and T4, gill Na+/K+-ATPase, the ability of the head kidney to secrete cortisol, and condition factor) and hepatic oxidative stress indicators (reduced glutathione, glutathione peroxidase, and lipid peroxidation) were measured after 96 h (acute exposure to 0-2.67 mg/L Se) and 30 days (sub-chronic exposure to 0-0.16 mg/L). Acute exposure to waterborne sodium selenite significantly increased plasma cortisol levels (control=0.01+/-0.0 ng/mL, and 2.52 mg/L Se=73.5+/-22 ng/mL) and plasma glucose levels (control=0.75+/-0.1 mg/mL, and 3.60 mg/L Se=1.64+/-0.2 mg/mL), but gill Na+/K+-ATPase activities, plasma T3 and T4 levels, and condition factor were unchanged. The 96 h acute selenite exposure decreased hepatic reduced glutathione levels (control=18.4+/-1.5 micromol/mg protein, and 3.60 mg/L Se=12.4+/-1.1 micromol/mg protein). Lipid peroxidation levels (0.03-0.08 U/mg protein) and glutathione peroxidase (3.7-6.0 mU/mg protein) activities significantly varied with treatment. The 30 days sub-chronic exposure increased plasma cortisol, T3, and T4, but there was no effect on plasma glucose levels, gill Na+/K+-ATPase activity, the ability to secrete cortisol, and condition factor. The 30 days sub-chronic exposure to selenite did not alter antioxidant activities or lipid peroxidation levels. These experiments show, for the first time, that exposure to waterborne selenite up to 0.1mg/L, activates the physiological stress response in fish but does not impair cortisol secretion after 30 days. The decrease in reduced glutathione in juvenile rainbow trout subjected to the acute sodium selenite exposure suggests that oxidative stress may play an important role in the effects of Se in fish.

Effects of long-term alachlor exposure on hepatic antioxidant defense and detoxifying enzyme activities in crucian carp (Carassius auratus)

Alachlor has been widely used in agriculture all over the world. It is suggested that it may be a carcinogen and also an environmental estrogen. In this paper, the physiological and biochemical perturbations of crucian carp (Carassius auratus) exposed to alachlor at different concentrations over 60 days were investigated. The gonadosomatic index (GSI) and hepatosomatic index (HSI) were measured. The activity of hepatic antioxidant defense and detoxifying enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the content of glutathione (GSH) were determined and compared with the control group. The result showed that GSI and HSI decreased significantly (P<0.05) in almost all treatments. The activities of SOD, CAT and GST were induced continuously (P<0.05), while the content of reduced glutathione (GSH) was inhibited on the whole. These changes reflect that the antioxidant systems of the tested fishes were affected. The possible defense mechanistic implications about the changes were thus discussed. Furthermore, hepatic SOD and GST were sensitive to alachlor at low concentration, indicating that they might be potential biomarkers in early detection of alachlor contamination in aquatic ecosystems.

Bioaccumulation and ROS generation in liver of freshwater fish, goldfish Carassius auratus under HC Orange No 1 exposure

HC Orange No. 1 (CAS No. 54381-08-7, 2-nitro-4'-hydroxydiphenylamine) is used as a color additive in hair dyes. In this study, laboratory experiment was carried out to determine HC Orange No. 1 bioaccumulation and oxidative stress in the liver of freshwater fish, goldfish Carassius auratus. Fish were exposed to different concentrations (0.05, 0.1, 0.2, 0.5, and 1.0 mg/L) of HC Orange No. 1 for 10 days, with one group assigned as control. The accumulation of HC Orange No. 1 in liver increased with the exposure concentration (R(2) = 0.94). A secondary spin trapping technique was used followed by electron paramagnetic resonance (EPR) analysis to study the reactive oxygen species (ROS) production. On the basis of the hyperfine splitting constants and shape of the EPR spectrum, the ROS generated in fish liver after exposure was identified as hydroxyl radical (*OH). There is a good correlation between the exposure concentrations and *OH generation (R(2) = 0.92). The *OH signal intensity of the EPR spectrum showed a significant increase (P < 0.05) when the HC Orange No. 1 concentration was 1.0 mg/L, compared with that of the control. A good positive relationship (R(2) = 0.95) was found between the *OH formation and accumulation level of HC Orange No. 1 in liver. The changes of the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and contents of reduced glutathione (GSH) were also detected. These observations indicated a possible mechanism of oxidative stress induced by HC Orange No. 1 on fish.

Effects of waterborne Cd exposure on glutathione metabolism in Nile tilapia (Oreochromis niloticus) liver

To explore the effects of cadmium (Cd) exposure of tilapia (Oreochromis niloticus) on hepatic glutathione (GSH) metabolism, tilapias were exposed to 3.0 mg/L Cd for 1, 5, 10, 20, and 40 days. The contents of reduced GSH and oxidized GSH (GSSG) and the activities of enzymes involved in GSH metabolism and the GSSG-GSH ratio were investigated. The results showed that reduced GSH were depleted progressively whereas the GSSG-GSH ratio increased. The activities of selenium-dependent glutathione peroxidase, glutathione S-transferase and glucose-6-phosphate dehydrogenase, and GSSG levels increased initially and decreased subsequently but still higher than the controls. Glutathione reductase activity dropped on the 40th day. A transient increase in gamma-glutamylcysteine syntheses activity was detected on the 20th day. The findings demonstrated that the hepatic GSH pool showed different reaction patterns associated with exposure period. The homeostatic mechanism was activated by short-term Cd exposure while the response ability weakened for a longer exposure.

Contaminants-induced oxidative damage on the carp Cyprinus carpio collected from the upper Yellow River, China

The Yellow River, the second largest river in China, is the most important resource of water supply in North China. In the last 40 years, even in the upper Yellow River, with the development of industry and agriculture, more and more contaminants have been discharged into this river and greatly polluted the water. Although a routine chemical component analysis has been performed, little is known about the real toxic effects of the polluted water on organisms at environmental level. To explore whether the pollutants induced oxidative stress and damage to aquatic organisms, malondialdehyde (MDA) level and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) in hepatopancreas, kidney and intestine of the field-collected carp Cyprinus carpio from a mixed polluted (Lanzhou Region, LZR) and a relatively unpolluted (Liujiaxia Region, LJXR) sites of the upper Yellow River were measured. The results showed that when the values of LZR compared with those of LJXR, SOD and GST activities increased and GPx activity decreased significantly in all the three organs (P < 0.05-0.01); CAT activity decreased but MDA level increased significantly (P < 0.05-0.01) only in kidney and intestine. In conclusion, the results of this study suggest that the pollutants can induce obvious oxidative damage in the carp, and the SOD, GST and GPx might be better indicators for the oxidative damage in aquatic organisms.