Accumulation and oxidative stress biomarkers in Japanese flounder larvae and juveniles under chronic cadmium exposure

This study investigated how Cd exposure affected oxidative biomarkers in Japanese flounder, Paralichthys olivaceus, at early life stages (ELS). Fish were exposed to waterborne Cd (0–48 µg L^− 1) from embryonic to juvenile stages for 80 days. Growth, Cd accumulation, activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione S-transferase (GST, EC 2.5.1.18), and levels of glutathione (GSH) and lipid peroxidation (LPO) were investigated at three developmental stages. Flounder growth decreased and Cd accumulation increased with increasing Cd concentration. In metamorphosing larvae, CAT and SOD activities were inhibited and GSH level was elevated, while LPO was enhanced by increasing Cd concentrations. CAT and GST activities of settling larvae were inhibited but GSH level was elevated at high Cd concentrations. In juveniles, SOD activity and LPO level were increased but GST activity was inhibited as Cd concentration increased. Antioxidants in flounder at ELS were able to develop ductile responses to defend against oxidative stress, but LPO fatally occurred due to Cd exposure. These biochemical parameters could be used as effective oxidative biomarkers for evaluating Cd contamination and toxicity in marine environments: CAT, SOD, GSH, and LPO for metamorphosing stage; CAT, GSH, and GST for settling stage; and SOD, GST, and LPO for juvenile stage.     

Modulation of antioxidant defence system in brain of rainbow trout (Oncorhynchus mykiss) after chronic carbamazepine treatment

We investigated the effect of long-term exposure to CBZ on the antioxidant system in brain tissue of rainbow trout. Fish were exposed to sublethal concentrations of CBZ (1.0 μg/L, 0.2 mg/L or 2.0 mg/L) for 7, 21, and 42 days. Oxidative stress indices (LPO and CP) and activities of antioxidant enzymes (SOD, CAT, GPx and GR) in fish brain were measured. In addition, non-enzymatic antioxidant (GSH) was determined after 42 days exposure. Carbamazepine exposure at 0.2 mg/L led to significant increases (p < 0.05) of LPO and CP after 42 days and, at 2.0 mg/L, after 21 days. Activities of the antioxidant enzymes SOD, CAT, and GPx in CBZ-treated groups slightly increased during the first period (7 days). However, activities of all measured antioxidant enzymes were significantly inhibited (p < 0.05) at 0.2 mg/L exposure after 42 days and after 21 days at 2.0 mg/L. After 42 days, the content of GSH in fish brain was significantly lower (p < 0.05) in groups exposed to CBZ at 0.2 mg/L and 2.0 mg/L than in other groups. Prolonged exposure to CBZ resulted in excess reactive oxygen species formation, finally resulting in oxidative damage to lipids and proteins and inhibited antioxidant capacities in fish brain. In short, a low level of oxidative stress could induce the adaptive responses of antioxidant enzymes, but long-term exposure to CBZ could lead to serious oxidative damage in fish brain.     

Ultraviolet light-induced oxidative stress: Effects on antioxidant response of Helicoverpa armigera adults

Ultraviolet (UV) light (blacklight), which emits UV in the range of 320-400 nm, has been used worldwide in light trapping of insect pests. In this article, we test the hypothesis that one of the effects of UV light irradiation is to increase oxidative stress on insects. The effects of UV light irradiation on total antioxidant capacity, malondialdehyde (MDA) and protein carbonyl contents and the activities of superoxide dismutase (SOD), catalase (CAT), peroxidases (POX) and glutathione-S-transferase (GST) were investigated in Helicoverpa armigera adults. The adults were exposed to UV light for various time periods (0, 30, 60 and 90 min). We found that exposure to UV light for 30 min resulted in increased total antioxidant capacity, protein carbonyl content and activities of SOD, CAT, POX and GST. When the exposure time lasted for 60 and 90 min, the protein carbonyl content and activities of CAT and GST remained significantly higher than the control. However, the antioxidant capacity and SOD activity returned to control levels, and POX activity decreased at 60 and 90 min. Our results confirm the hypothesis that UV light irradiation increases the level of oxidative stress in H. armigera adults.     

GC-FPD measurement of urinary dialkylphosphate metabolites of organophosphorous pesticides as pentafluorobenzyl derivatives in occupationally exposed workers and in a general population in Shanghai (China)

Measurement of organophosphorus (OP) pesticide metabolites in human biological fluids is an important biomarker of pesticides exposure. We measured the urinary excretion of OP pesticide metabolites to evaluate occupational and non-occupational exposure to OP pesticides in the Chinese population in Shanghai (Eastern China). We collected urine samples from 30 exposed workers in a dimethoate emulsion packing division and from 60 healthy adults without any report of occupational exposure. DMP, DMTP, DMDTP, DEP, DEDP and DEDTP were measured by GC-FPD after derivatization with pentafluorobenzyl bromide. The LOQ values (1 mL urine) were 2.0 μg/L for DMP and DETP, 4.0 μg/L for DEP and DEDTP, 8.0 μg/L for DMDTP, and 10.0 μg/L for DMTP. Dimethyl phosphates were detected in the majority of the urine samples, i.e., 90–100% in the exposed group and 80–87% in the control group. The concentration of the urinary diethyl phosphates DEP and DETP was above the LOQ values in 40 and 20% of samples for the exposed group, and in 50 and 30% of the samples for the control group, respectively. DEDTP was not detectable in the urine samples except for a post-shift exposed worker (detection frequency, 6.7%). Median creatinine-adjusted values (μg/g cr.) for DAP in Chinese with pre-shift, post-shift and without occupational exposure to OP were 316, 584 and 170 for DMP, below LOQ, 115 and 114 for DEP, 840, 1730 and 693 for DMTP, and 255, 756 and 135 for DMDTP, respectively. In all subjects, the highest excretion levels were found for DMTP. Several OP pesticide metabolites were frequently detected in urine samples of both populations studied.     

The effect of Myrtus communis L. ethanol extract on the small intestine and lungs in experimental thermal burn injury

Thermal trauma can damage organs away from the skin burn site and lead to multiple organ dysfunction. Following thermal injury, all tissues are exposed to ischemia, and as a result, resuscitation and reperfusion occur during the burning shock. Burn damage starts systemic inflammatory reactions that produce toxins and reactive oxygen radicals that lead to peroxidation. This study aimed to investigate, for the first time, the possible antioxidant effects of Myrtus communis ethanol extract on burn-induced oxidative distant organ injury orally. The thermal trauma was generated under ether anesthesia by exposing the dorsum of rats to 90 ^°C water bath for 10 s. 100 mg/kg/day Mrytus communis ethanol extract was applied orally for two days. Malondialdehyde (MDA) and glutathione (GSH) levels, glutatinone-S-transferase (GST), superoxidedismutase (SOD) and catalase (CAT) activities were determined to detect the possible antioxidant effects of myrtle on small intestine and lung tissues. Burn damage significantly increased MDA levels in lung and small intestine tissues, and significantly decreased GSH levels, CAT and GST activities in the small intestine and lung tissues compared to control group. Mrytus communis ethanol extract decreased MDA level and increased GSH level, SOD, CAT and GST activities significantly in either small intestine or lung tissues. Mrytus communis extract may be an ideal candidate to be used as an antioxidant adjunct to improve oxidative distant organ damage to limit the systemic inflammatory response and decreasing the recovery time after thermal injury.     

铜对梨形环棱螺抗氧化酶活性和金属硫蛋白含量的影响

本实验采用暴露重金属的方法,研究了不同浓度硫酸铜（Cu2+ 分别为0、0.005、0.01、0.02、0.05 mg/L）在不同暴露时间（0—14d）下对梨形环棱螺（Bellamya purificata）过氧化氢酶(CAT)、超氧化物歧化酶（SOD）、谷胱甘肽硫转移酶（GST）的活性、还原性谷胱甘肽（GSH）和金属硫蛋白（MT）含量的影响,以探讨Cu2+ 对梨形环棱螺的氧化损伤及其防御作用的机理,并为水环境Cu2+ 污染的早期诊断及生态风险评价提供科学的依据。结果表明：Cu2+对梨形环棱螺肝脏和鳃中CAT、SOD、GST、GSH 和MT 均有明显影响,表现出时间剂量效应。SOD在前4天、CAT在前3天酶活性总体上表现出诱导趋势, GST在前4天酶活性处于诱导状态,随着暴露时间的延长,酶活性下降,到第5天时表现出抑制趋势;随着时间的进一步增长,至14d时, 0.005 mg/L剂量组酶活性维持在正常值附近波动, 0.01 mg/L剂量组酶活性被诱导, 0.02 mg/L剂量组酶活性在肝脏中表现为诱导而在鳃中则被抑制,0.05 mg/L剂量组酶活性被抑制。肝脏和鳃GSH含量的变化与GST相似,在短时间内表现出诱导效应,肝脏GSH在暴露的前5天、鳃GSH在暴露的前4天均处于诱导状态,随着暴露时间的延长,0.005 mg/L剂量组表现出诱导,0.05 mg/L剂量组则受到抑制。MT在整个实验期间均处于诱导状态,各剂量组在0.5d被极显著诱导,随后MT含量出现起伏波动,有上升和下降,至第14天时达到一稳定水平。其中,0.01 mg/L剂量组肝脏的MT在整个实验期间均被极显著地诱导（P <0.01）,0.01 mg/L 剂量组的鳃组织MT除第10天外也被极显著诱导（P <0.01）。在暴露14d时,除0.05 mg/L剂量组的肝脏MT外,其余处于极显著诱导状态（P <0.01）。     

Tissue-specific inhibition and recovery of esterase activities in Lumbricus terrestris experimentally exposed to chlorpyrifos

Exposure and effect assessment of organophosphate (OP) pesticides generally involves the use of cholinesterase (ChE) inhibition. In earthworm, this enzyme activity is often measured in homogenates from the whole organism. Here we examine the tissue-specific response of ChE and carboxylesterase (CE) activities in Lumbricus terrestris experimentally exposed to chlorpyrifos-spiked field soils. Esterases were measured in different gut segments and in the seminal vesicles of earthworms following acute exposure (2 d) to the OP and during 35 d of a recovery period. We found that inhibition of both esterase activities was dependent on the tissue. Cholinesterase activity decreased in the pharynx, crop, foregut and seminal vesicles in a concentration-dependent way, whereas CE activity (4-nitrophenyl valerate) was strongly inhibited in these tissues. Gizzard CE activity was not inhibited by the OP, even an increase of enzyme activity was evident during the recovery period. These results suggest that both esterases should be determined jointly in selected tissues of earthworms. Moreover, the high levels of gut CE activity and its inhibition and recovery dynamic following OP exposure suggest that this esterase could play an important role as an enzymatic barrier against OP uptake from the ingested contaminated soil.     

Increased recovery of brain acetylcholinesterase activity in dichlorvos-intoxicated European eels Anguilla anguilla by bath treatment with N-acetylcysteine

Organophosphate (OP) pesticides are widely used as antiparasitic chemicals in finfish aquaculture. However, current antidotes cannot be applied to treat intoxicated fish. We showed in previous studies the importance of glutathione (GSH) metabolism in pesticide resistance of the European eel Anguilla anguilla L. The present work studied the effects of the antioxidant and glutathione pro-drug N-acetyl-L-cysteine (NAC) on the recovery of European eels exposed for 96 h to a sublethal concentration (0.17 mg l(-1); 20% of its 96 h LC50) of the OP pesticide dichlorvos (2,2-dichlorovinyl dimethyl phosphate; DDVP). This insecticide and acaricide decreased muscular GSH content and increased oxidised glutathione (GSSG), lowering the GSH:GSSG ratio, which is indicative of a condition of oxidative stress. Acetylcholinesterase (AChE) and glutathione reductase (GR) activities in the brain, which were biomarkers of neurotoxicity and oxidative stress, respectively, were also highly inhibited. Recovery in a 0.5 mM (81.6 mg l(-1)) NAC concentration ameliorated muscular GSH depletion, GSH:GSSG ratio, and the inhibition of brain AChE and GR activities. Hence, this is the first evidence of improved recovery of organophosphate-poisoned fish by bath treatments.     

Alterations in the general condition,biochemical parameters and locomotor activity in Cnesterodon decemmaculatus exposed to commercial formulations of chlorpyrifos,glyphosate and their mixtures

The Pampean region, an extensive area of South America is continuously impacted by agricultural activities and the pesticides related to them like chlorpyrifos and glyphosate. Both pesticides have been registered in freshwater bodies of the region. One of the most abundant and widely distributed fish species in Pampean streams is Cnesterodon decemmaculatus, which have to cope with this altered scenario.In the present study the toxicity of Clorfox^® and Roundup Max^®, the commercial formulations of chlorpyrifos and glyphosate, respectively, and their mixture where evaluated using a set of biomarkers at different biological organization levels in fish exposed to relevant environmentally pesticides concentrations. Somatic indexes such as the condition factor (K), and the hepato-somatic index (HSI), the locomotor activity through the distance traveled and the average speed, the enzymatic activities of acetylcholinesterase (AChE) in brain and muscle, catalase (CAT) in muscle and liver, glutathione-S-transferase (GST) in brain, liver, muscle and gills, aspartate amino-transferase (AST), alanine amino-transferase (ALT), AST/ALT ratio and alkaline phosphatase (ALP) in liver were measured on C. decemmaculatus. Adult females were exposed during 6 weeks to the following concentrations: 0.0084 μl/l and 0.00084 μl/l of Clorfox (CF), 0.2 and 2 mg/l of Roundup Max (RM) and all the combinations of these concentrations. The CF exposure caused a decrease in the condition factor and in the locomotor activity parameters and induced an increase brain AChE, liver CAT activity and AST/ALT ratio. On the other hand, the exposure to RM produced a decrease in liver GST, AST/ALT ratio and ALP activity. Finally, some pesticide combinations decrease general condition and liver GST activities, and increase brain GST and liver ALP activities. Different responses in biomarkers were observed in mixtures treatments, reflecting the complex interactions between these toxics and suggesting a suppressive action of RM on CF effects.Since the concentrations we tested are environmentally relevant and the overall fish health condition was affected, the presence of these pesticides in freshwater systems could impose a risk for populations by causing deleterious effects on C. decemmaculatus in Pampean region.     

Role of selenium on antioxidant capacity in methomyl-treated mice

Methomyl carbamate is a pesticide widely used in the control of insects. The present work aims at studying the effect of selenium on the antioxidant system of methomyl-treated mice. Swiss albino mice were intraperitoneally administered a single dose of methomyl (7 mg/Kg body weight). Mice of another group were injected with sodium selenite (5 pmole/Kg b.wt.) 7 days before methomyl intoxication. After 24 hours, methomyl exposure resulted in significant increase in lactic dehydrogenase activity (LDH). The antioxidant capacity of hepatic cells in terms of the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST) and glutathione (GSH) content was diminished. It appears that methomyl exerts its toxic effect via peroxidative damage to hepatic, renal and splenic cell membranes. Also, methomyl induced DNA damage in these organs as detected by alkaline filter elution technique. The distribution of methomyl in different organs of mice was detected by HPLC. Selenium administration prior to methomyl injection produced pronounced protective action against methomyl effects. It is observed that selenium enhances the endogenous antioxidant capacity of the cells by increasing the activities of SOD, CAT, GR and GST as well as increasing GSH content. The activity of LDH was decreased in blood and the damage of DNA was suppressed comparable to controls. In conclusion, the adverse effects of methomyl in mice could be ameliorated by selenium.     

Effect of copper exposure on GST activity and on the expression of four GSTs under oxidative stress condition in the monogonont rotifer, Brachionus koreanus

Glutathione S-transferases (GSTs; EC 2.5.1.18) are major enzymes that function in Phase II detoxification reactions by catalyzing the conjugation of reduced glutathione through cysteine thiol. In this study, we cloned and sequenced four GST genes from the monogonont rotifer Brachionus koreanus. The domain regions of four Bk-GSTs showed a high similarity to those of other species. In addition, to evaluate the potential of GST genes as an early warning signal for oxidative stress, we exposed sublethal concentrations of copper (Cu) to B. koreanus and measured glutathione (GSH) contents and several antioxidant enzymes such as glutathione S-transferase (GST), glutathione peroxidase (GPx; EC 1.11.1.9), and glutathione reductase (GR; EC 1.8.1.7). The reactive oxygen species (ROS) at 12 h and 24 h after copper exposure increased significantly. GSH contents however did not increase significantly and even it decreased at 0.24 mg/L at 12 h. The activities of several antioxidant enzymes, particularly GPx and GR, showed a dramatic increase in 0.24 mg/L of CuCl₂. Messenger RNAs of each Bk-GST showed different patterns of modulations according to GST types, and particularly, Bk-GST-omega, Bk-GST-sigma, and Bk-GST zeta genes were highly sensitive to Cu. These results indicate that Bk-GSTs, functioning as one of the enzymatic defense mechanisms particularly in the early stage of oxidative stress response, were induced by Cu exposure. This also suggests that these genes and related enzymes have a potential as biomarkers for a more sensitive initial stress response.     

The effects of selenium on oxidative stress biomarkers in the freshwater characid fish matrinxã, Brycon cephalus (Günther, 1869) exposed to organophosphate insecticide Folisuper 600 BR (methyl parathion)

Methyl parathion (MP), an organophosphate widely applied in agriculture and aquaculture, induces oxidative stress due to free radical generation and changes in the antioxidant defense system. The antioxidant roles of selenium (Se) were evaluated in Brycon cephalus exposed to 2 mg L(-1) of Folisuper 600 BR (MP commercial formulation - MPc, 600 g L(-1)) for 96 h. Catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) levels in the gills, white muscle and liver were evaluated in fish fed on diets containing 0 or 1.5 mg Se kg(-1) for 8 weeks. In fish treated with a Se-free diet, the MPc exposure increased SOD and CAT activities in all tissues. However, the GPx activity decreased in white muscle and gills whereas no alterations were observed in the liver. MPc also increased GST activity in all tissues with a concurrent decrease in GSH levels. LPO values increased in white muscle and gills and did not change in liver after MPc exposure. A Se-supplemented diet reversed these findings, preventing increases in LPO levels and concurrent decreases in GPx activity in gills and white muscle. Similarly, GSH levels were maintained in all tissue after MPc exposure. These results suggest that dietary Se supplementation protects cells against MPc-induced oxidative stress.     

Comparative xenobiotic metabolism capacities and pesticide sensitivity in adults of Solea solea and Solea senegalensis

The measurement of enzymatic activities involved in xenobiotic biotransformation was carried out in adults of Solea solea and Solea senegalensis. The hepatic enzymes analysed were cytochrome P450 (CYP) related activities using eight fluorometric substrates and carboxylesterases (CbE). The conjugating activities of glutathione S-transferase (GST) and UPD-glucuronosyltransferase (UDPGT) were also assessed. Specific mammalian inhibitors were used as diagnostic tools for related activities of CYP1A (α-naphthoflavone; αNF), CYP2B6 and CYP2C19 (ticlopidine) and CYP3A4 (ketoconazole). The in vitro sensitivity to organophosphorous pesticides (OP) was tested in the S10 homogenate of brain (acetylcholinesterase-AChE) and liver (CbE). Furthermore, the pesticide chlorpyrifos oxon (CLPO) was used to explore the OP sensitivity of CbE of both species in two subcellular fractions (microsomes and cytosol), using two substrates. Overall, only two parameters confirmed species differences: EROD and cytosolic CbE being significantly elevated (p < 0.05) in the common sole, S. solea. A high inhibition of CYP1A related activities using several fluorometric substrates (ER, MR and CEC) after in vitro incubation with αNF confirmed all measure CYP1A1-related activities whereas ketoconazole was more specific for BFCOD (CYP3A4). Pesticide sensitivity was similar for brain AChE but hepatic CbE had a protective role that was species and pesticide dependent.     

Expression of the housefly acetylcholinesterase in a bioreactor and its potential application in the detection of pesticide residues

Acetylcholinesterase is a key enzyme of the animal nerve system. The enzyme is the primary target of organophosphorous (OP) and carbamate (CB) insecticides. The insect AChE is being extensively used in development of new insecticides or in vitro selection of the new designed insecticides, and in pharmacological and toxicological field. Rapid assays using AChE-based methods have been proposed as an efficient and rapid method for the detection of pesticides, especially in many Asian markets. In this study, the acetylcholinesterase gene was cloned from housefly (Musca domestica) susceptible to organophosphate (OP) and carbamate (CB) insecticides, and expressed in baculovirus-insect cells system using a bioreactor with oxygen supplementation. The recombinant housefly AChE was purified using ammonium sulfate precipitation and procainamide affinity chromatography, and approximately 0.42 mg of the purified AChE with high biological activity (118.9 U/mg) was obtained from 100 ml of culture solution. The purified AChE was highly sensitive to OP and CBs insecticides. In conclusion, an efficient expression and purification system has been developed for large-scale production of recombinant housefly AChE. The recombinant enzyme is potential to be used for the detection of pesticide residues.     

Antioxidant responses of citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae), exposed to thermal stress

Relatively low or high temperatures are responsible for a variety of physiological stress responses in insects and mites. Induced thermal stress was recently associated with increased reactive oxygen species (ROS) generation, which caused oxidative damage. In this study, we examined the time-related effect of the relatively low (0, 5, 10, and 15 °C) or high (32, 35, 38, and 41 °C) temperatures on the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidases (POX), and glutathione-S-transferase (GST), and the total antioxidant capacity (TEAC) of the citrus red mite, Panonychus citri (McGregor). The malondialdehyde (MDA) concentration, as a marker of lipid peroxidation in organisms, was also measured in the citrus red mite under thermal stress conditions. Results showed that SOD and GST activities were significantly increased and play an important role in the process of antioxidant response to thermal stress. Lipid peroxidation levels increased significantly (P < 0.001) and changed in a time-dependent manner. CAT and POX activity, as well as TEAC, did not vary significantly and play a minor role to remove the ROS generation. These results suggest that thermal stress leads to oxidative stress and antioxidant enzymes play an important role in reducing oxidative damage in the citrus red mite.     

Rye oxidative stress under long term Al exposure

Aluminium (Al) toxicity decreases plant growth. Secale cereale L. is among the most Al-tolerant crop species. In order to study the response to Al-long term exposure, two rye genotypes with different Al sensitivity (‘D. Zlote’ and ‘Riodeva’) were exposed to 1.11 and 1.85 mM Al and the antioxidant responses were followed for 2 and 3 weeks in roots and leaves. Al toxicity signals, such as a severe decrease in root growth, occurred sooner in ‘Riodeva.’ The antioxidant response was dependent on the genotype, the organ, Al concentration and the exposure period. Al-exposed roots of ‘D. Zlote’ showed earlier enhancements of APX, SOD and G-POX activities than those of ‘Riodeva.’ ‘D. Zlote’ roots showed stimulation of the AsA–GSH cycle after the second week (when root growth inhibition was less severe), while later (when severe root growth inhibition was observed), oxidation of AsA and GSH pools was observed. In leaves of both genotypes, CAT, SOD and G-POX activities increased with Al exposure. In these leaves, the effect of AsA–GSH was time dependent, with maximum oxidation at the second week, followed by recovery. We confirmed that the oxidation state of AsA and GSH pools is involved in the detoxification of Al-induced oxidative stress. Moreover, our data demonstrate that the production of ROS does not correlate with the Al-induced root growth decrease. Finally, the differences observed over time indicate that long term exposure may provide additional information on rye sensitivity to Al, and contribute to a better understanding of this species’ mechanisms of Al tolerance.     

Modulation of glutathione-related antioxidant defense system of fish chronically treated by the fungicide propiconazole

Recently, residual fungicides are generally recognized as relevant sources of aquatic environmental pollutants. However, the toxicological effects of these contaminants have not been adequately researched. In this study, the chronic effect of PCZ, a triazole-containing fungicide commonly present in aquatic environment, on GSH-related antioxidant system and oxidative stress indices of rainbow trout (Oncorhynchus mykiss) were investigated. Fish were exposed at sub-lethal concentrations of PCZ (0.2, 50 and 500 μg/L) for 7, 20 and 30 days. GSH levels and GSH-related enzyme activities, including GPx, GR and GST, were quantified in three tissues—liver, gill and muscle. The levels of LPO and CP were also measured as makers of oxidative damage. In addition, the correlations of the measured parameters in various tissues were evaluated by using PCA. The results of this study indicate that chronic exposure of PCZ has resulted in different responses in various tissues and the gill was the most sensitive tissue; however, before these parameters are used as potential biomarkers for monitoring residual fungicides in aquatic environment, more detailed experiments in laboratory need to be performed in the future.     

Systemic oxidative stress in children and teenagers with Down syndrome

Aims

The aim of this study was to evaluate the antioxidant status and oxidative stress biomarkers in the blood of children and teenagers with Down syndrome.

Main methods

The analysis of enzymatic antioxidant defenses, such as the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione transferase (GST), non-enzymatic antioxidants, such as levels of reduced glutathione (GSH), uric acid (UA) and vitamin E, as well as oxidative damage indicators, such as protein carbonyls (PC) levels and lipoperoxidation (TBARS), of DS individuals (n = 20) compared to healthy controls (n = 18). Except the vitamin E was measured by HPLC, all other markers were measured spectrophotometrically.

Key Findings

Antioxidant enzymes analysis showed significant increases in the SOD (47.2%), CAT (24.7%) and GR (49.6%) activities in DS subjects. No significant difference in GPx activity was detected while GST activity (61.2%) was decreased, and both responses may be consequence of the depletion of GSH (24.9%) levels. There were no significant differences in TBARS levels, while PC levels showed decreased (31.7%) levels compared to healthy controls, which may be related to the increase (16.1%) found in serum UA. Levels of vitamin E showed no significant differences between DS individuals compared to controls.

Significance

The results revealed a systemic pro-oxidant status in DS individuals, evidenced by the increased activity of some important antioxidant enzymes, together with decreased GSH levels in whole blood and elevated UA levels in plasma, probably as an antioxidant compensation related to the redox imbalance in DS individuals.     

The use of biomarkers in the antioxidant responses of Daphnia magna to the acute and chronic exposure to no. 20 diesel oil and 2,4-dichlorophenol

Abstract

The effects of no. 20 diesel oil exposure, 2,4-dichlorophenol (2,4-DCP) exposure and combined exposure on the antioxidant defences of Daphnia magna have been studied systematically for the first time. Daphnia magna was exposed for 1 day or 10 days to several concentrations of 0, 0.005, 0.01, 0.05, 0.1, 0.5 or 1.0 mg L^?1 solutions. Antioxidant defences consisting of the levels of reduced glutathione (GSH) and glutathione disulfide (GSSG) and activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), selenium dependent glutathione peroxidase (Se-GPx) and glutathione S-transferase (GST) of daphnids were determined to evaluate their protective roles and to analyse the occurrence of oxidative stress. The possible antioxidant defence mechanisms are discussed. Furthermore, GST can be a potential biomarker and an early-warning index for the pollutants in waters in that GST responded sensitively to 1 day and 10 days of exposure to diesel oil and 2,4-DCP and 10 days of combined exposure. Crossover comparisons showed an antagonistic action about the no-observed-effect concentration (NOEC) against Daphnia magna, which needs further studies.