Detoxification and oxidative stress responses along with microcystins accumulation in Japanese quail exposed to cyanobacterial biomass

The cyanobacterial exposure has been implicated in mass mortalities of wild birds, but information on the actual effects of cyanobacteria on birds in controlled studies is missing. Effects on detoxification and antioxidant parameters as well as bioaccumulation of microcystins (MCs) were studied in birds after sub-lethal exposure to natural cyanobacterial biomass. Four treatment groups of model species Japanese quail (Coturnix coturnix japonica) were exposed to controlled doses of cyanobacterial bloom during acute (10 days) and sub-chronic (30 days) experiment. The daily doses of cyanobacterial biomass corresponded to 0.2-224.6 ng MCs/g body weight. Significant accumulation of MCs was observed in the liver for both test durations and slight accumulation also in the muscles of the highest treatment group from acute test. The greatest accumulation was observed in the liver of the highest treatment group in the acute test reaching average concentration of 43.7 ng MCs/g fresh weight. The parameters of detoxification metabolism and oxidative stress were studied in the liver, heart and brain. The cyanobacterial exposure caused an increase of activity of cytochrome P-450-dependent 7-ethoxyresorufin O-deethylase representing the activation phase of detoxification metabolism. Also the conjugation phase of detoxification, namely the activity of glutathione-S-transferase, was altered. Cyanobacterial exposure also modulated oxidative stress responses including the level of glutathione and activities of glutathione-related enzymes and caused increase in lipid peroxidation. The overall pattern of detoxification parameters and oxidative stress responses clearly separated the control and the lowest exposure group from all the higher exposed groups. This is the first controlled study documenting the induction of oxidative stress along with MCs accumulation in birds exposed to natural cyanobacterial biomass. The data also suggest that increased activities of detoxification enzymes could lead to greater biotransformation and elimination of the MCs at the longer exposure time.     

Dietary ascorbic acid and alpha-tocopherol mitigates oxidative stress induced by copper in the thornfish Terapon jarbua

The protective effects of vitamins C and E against oxidative stress were evaluated in various tissues of thornfish Terapon jarbua exposed to copper. Preliminary bioassay tests performed with copper and T. jarbua revealed that 4.0, 2.5 and 1.0 mg L(-1) of copper were lethal (LC(100)), medial lethal (LC(50)) and sublethal (LC(0)) respectively. Oxidative stress parameters viz. lipid peroxidation, superoxide dismutase, catalase, glutathione peroxidase, and glutathione were evaluated in control and experimental fishes. Lipid peroxidation activity increased in tissues of copper exposed fishes, while the antioxidant system exhibited a reduction in their activity. On the contrary copper stressed fishes fed with vitamins C and E enriched pellet feed showed significant reduction in lipid peroxidation activity and the antioxidant levels increased reaching near normal levels comparable to control values. Bioaccumulation of copper was studied in addition to oxidative stress. Substantial copper residue was detected in the tissues of T. jarbua exposed to copper and the level of copper in tissues reduced when the fishes were treated with vitamins ensuring copper depuration and thereby protecting them against stress. We concluded that vitamin supplementation offered significant reduction of the oxidative stress mediated by copper and we discuss the possible application of vitamins in costal aquaculture process.     

Relationship between two oxidative stress biomarkers, malondialdehyde and 8-oxo-7,8-dihydro-2'-deoxyguanosine, in the freshwater bivalve Unio tumidus

This study addresses the question of the relation between cellular and genomic oxidative damages in freshwater bivalves in realistic conditions of exposure in the field. Membrane and genomic oxidative damages were studied by means of lipid peroxidation and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), respectively. Malondialdehyde (MDA) was used as an indicator of lipid peroxidation. The biomarkers were measured in the digestive gland and the gills of mussels (Unio tumidus) after 7 and 21 days of exposure in four ponds of the Moselle Basin, during three field studies conducted in 1999 and 2000. Effects measured at three sites (1R, 3C and 4M) were moderate and lipid peroxidation was slightly enhanced in mussels transferred in these ponds. In contrast, an important degradation was observed at site 2V reflected by a sharp increase in MDA and 8-oxodGuo concentrations in 2000. The biomarker responses agreed with the results of physicochemical analyses that indicated a worsening of water quality at the same site. Globally, a relationship was found between MDA increase and 8-oxodGuo formation, in the digestive gland after 7 days of exposure, and later in the gills (21 days). Responses of the digestive glands and gills to the oxidative parameters appeared correlated only after 21 days of exposure. The biomarkers selected confirmed their sensitivity for appraising the water quality of hydrosystems.     

Mobile phone radiation inhibits Vigna radiata (mung bean) root growth by inducing oxidative stress

During the last couple of decades, there has been a tremendous increase in the use of cell phones. It has significantly added to the rapidly increasing EMF smog, an unprecedented type of pollution consisting of radiation in the environment, thereby prompting the scientists to study the effects on humans. However, not many studies have been conducted to explore the effects of cell phone EMFr on growth and biochemical changes in plants. We investigated whether EMFr from cell phones inhibit growth of Vigna radiata (mung bean) through induction of conventional stress responses. Effects of cell phone EMFr (power density: 8.55 µW cm^− 2; 900 MHz band width; for ½, 1, 2, and 4 h) were determined by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H₂O₂) content, root oxidizability and changes in levels of antioxidant enzymes. Our results showed that cell phone EMFr significantly inhibited the germination (at ≥2 h), and radicle and plumule growths (≥1 h) in mung bean in a time-dependent manner. Further, cell phone EMFr enhanced MDA content (indicating lipid peroxidation), and increased H₂O₂ accumulation and root oxidizability in mung bean roots, thereby inducing oxidative stress and cellular damage. In response to EMFr, there was a significant upregulation in the activities of scavenging enzymes, such as superoxide dismutases, ascorbate peroxidases, guaiacol peroxidases, catalases and glutathione reductases, in mung bean roots. The study concluded that cell phone EMFr inhibit root growth of mung bean by inducing ROS-generated oxidative stress despite increased activities of antioxidant enzymes.     

Endosulfan induced biochemical changes in nitrogen-fixing cyanobacteria

Pesticide contamination in aquatic ecosystem including paddy fields is a serious global environmental concern. Cyanobacteria are also affected by pesticides as non- target organism. For better exploitation of cyanobacteria as biofertiliser, it is indispensable to select tolerant strains along with understanding of their tolerance. Three cyanobacterial strains viz. Aulosira fertilissima, Anabaena variabilis and Nostoc muscorum were studied for their stress responses to an organochlorine pesticide 'endosulfan' with special reference to oxidative stress, role of proline and antioxidant enzymes in endosulfan induced free radical detoxification. Reduction in growth, photosynthetic pigments and carbohydrate of the test microorganisms were accompanied with increase in their total protein, proline, malondialdehye (MDA), superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) in higher endosulfan doses. Increased amount of MDA is indicative of formation of free radicals, while increased level of CAT, APX, SOD and proline indicated their involvement in free radical scavenging mechanism. In lower concentrations, test pesticide showed increase in photosynthetic pigments. Order of tolerance was Nostoc muscorum>Anabaena variabilis>Aulosira fertilissima.     

Mercury exposure and oxidative stress in communities of the Brazilian Amazon

This study was designed to assess possible associations between biomarkers of mercury (Hg) exposure and oxidative stress in fish-eating Amazonian communities. Clinical samples were obtained from riparians living in the Brazilian Amazon. Biomarkers of oxidative stress (glutathione - GSH, glutathione peroxidase - GSH-Px, catalase - CAT, activity and reactivation index of δ-aminolevulinate dehydratase - ALA-D (R%) were determined in blood. Total Hg was measured in whole blood (B-Hg), plasma (P-Hg) and hair (H-Hg). Association between biomarkers of Hg exposure and oxidative stress were examined using multiple regression models, including age, gender, alcohol consumption, smoking status, fish consumption and then stratified for gender. Significant inverse relations were observed between GSH-Px, GSH, CAT, ALA-D activity and B-Hg or H-Hg (p < 0.05). ALA-D reactivation index was positively related to B-Hg (p < 0.0001). P-Hg was directly related to ALA-D reactivation index and inversely associated with GSH-Px, GSH, and ALA-D activity (p < 0.05). When stratified for gender, women showed significant inverse associations between all biomarkers of Hg exposure and CAT (p < 0.05) or GSH (p < 0.05), while for men only P-Hg showed a significant inverse relation with GSH (p < 0.001). Our results clearly demonstrated an association between Hg exposure and oxidative stress. Moreover, for B-Hg, P-Hg and H-Hg gender differences were present.     

Effects of low-level exposure to xenobiotics present in paints on oxidative stress in workers

Paints are composed of an extensive variety of hazardous substances, such as organic solvents and heavy metals. Biomonitoring is an essential tool for assessing the risk to occupational health. Thus, this study analyzed the levels of biomarkers of exposure for toluene, xylene, styrene, ethylbenzene, and lead, as well as the oxidative stress biomarker alterations in painters of an industry. Lipid peroxidation biomarker (MDA), δ-aminolevulinate dehydratase (ALA-D), nonprotein thyol groups, superoxide dismutase and catalase (CAT) were analyzed in exposed and nonexposed subjects. We estimated which of the paint constituents have the greatest influence on the changes in the biomarkers of oxidative stress in this case of co-exposure. The results demonstrated that despite the fact that all the biomarkers of exposure were below the biological exposure limits, the MDA levels and antioxidant enzyme activities were increased, while nonprotein thyol groups and ALA-D levels were decreased in painters when compared with nonexposed subjects. After statistic test, toluene could be suggested as the principal factor responsible for increased lipid peroxidation and inhibition of ALA-D enzyme; however, further studies on the inhibition of ALA-D enzyme by toluene are necessary.     

Certain antioxidant enzymes of Allium cepa as biomarkers for the detection of toxic heavy metals in wastewater

The utility of antioxidant enzymes, viz glutathione-S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), as biomarkers of heavy metal pollution in water was investigated using the Allium cepa (onion) system. These antioxidant enzymes were assayed in onion bulbs exposed to certain heavy metals taken separately, the test metals taken in combination as well as the industrial wastewater especially found to contain these metals. GST exhibited significantly enhanced activity upon treatment with individual heavy metals. However, GR, SOD and CAT did not show such a pronounced increase in activities. At higher heavy metal concentrations, GR, SOD and CAT showed a steep decline while GST activity still showed a rise. Moreover, APX, GPX and MDHAR also exhibited remarkable induction with increase in the concentration of individual heavy metals. However, there was no significant change in DHAR activity with respect to the controls. Metabolites like ascorbate (ASC) and glutathione (GSH) exhibited significant decline with increase in the concentration of individual heavy metals while the level of H(2)O(2) continued to display the rise up to a heavy metal concentration of 100 microM, after which it showed a gradual decline. A. cepa bulbs treated with wastewater sample showed enzyme activity profiles similar to that shown with heavy metals, thereby suggesting the presence of heavy metals in the test wastewater. Atomic absorption spectrophotometry also detected large amounts of Cd, Cr, Cu, Hg, Pb and Zn in the test water sample. The metal mixture, containing the amounts of heavy metals equivalent to those found in the wastewater, resulted in steep declines in GR, SOD and CAT activities in A. cepa while GST showed a rise. However, when this metal mixture was diluted to 2000-fold, GR, SOD and CAT also showed enhanced activities compared with the controls. Contrary to the above finding, APX, GPX and MDHAR exhibited the rise in activities in A. cepa exposed to the metal mixture at all dilutions. In the presence of cycloheximide, all the enzymes returned to the levels of untreated controls while chloramphenicol did not have any effect on the test enzymes, thereby suggesting de novo protein synthesis of the test antioxidant enzymes in the cytosolic compartment of the cell as a result of exposure to the heavy metals.     

Toxicological assessment of indium nitrate on aquatic organisms and investigation of the effects on the PLHC-1 fish cell line

Indium nitrate is mainly used as a semiconductor in batteries, for plating and other chemical and medical applications. There is a lack of available information about the adverse effects of indium compounds on aquatic organisms. Therefore, the toxic effects on systems from four trophic levels of the aquatic ecosystem were investigated. Firstly, the bacterium Vibrio fischeri, the alga Chlorella vulgaris and the cladoceran Daphnia magna were used in the toxicological evaluation of indium nitrate. The most sensitive model was V. fischeri, with a NOAEL of 0.02 and an EC(50) of 0.04 mM at 15 min. Although indium nitrate should be classified as harmful to aquatic organisms, it is not expected to represent acute risk to the aquatic biota. Secondly, PLHC-1 fish cell line was employed to investigate the effects and mechanisms of toxicity. Although protein content, neutral red uptake, methylthiazol metabolization, lysosomal function and acetylcholinesterase activity were reduced in cells, stimulations were observed for metallothionein levels and succinate dehydrogenase and glucose-6-phosphate dehydrogenase activities. No changes were observed in ethoxyresorufin-O-deethylase activity. To clarify the main events in PLHC-1 cell death induced by indium nitrate, nine modulators were applied. They were related to oxidative stress (alpha-tocopherol succinate, mannitol and sodium benzoate), disruption of calcium homeostasis (BAPTA-AM and EGTA), thiol protection (1,4-dithiotreitol), iron chelation (deferoxiamine) or regulation of glutathione levels (2-oxothiazolidine-4-carboxylic acid and malic acid diethyl ester). The main morphological alterations were hydropic degeneration and loss of cells. At least, in partly, toxicity seems to be mediated by oxidative stress, and particularly by NADPH-dependent lipid peroxidation.     

Responses of antioxidant defenses to Cu and Zn stress in two aquatic fungi

Aquatic hyphomycetes are fungi that play a key role in plant litter decomposition in streams. Even though these fungi occur in metal-polluted streams, the mechanisms underlying their tolerance to metals are poorly documented. We addressed the effects of Zn and Cu in Varicosporium elodeae and Heliscus submersus by examining metal adsorption to cell walls, plasma membrane integrity and production of reactive oxygen species at metal concentrations inhibiting biomass production in 50% or 80%. The activity of the enzymes catalase, superoxide dismutase and glucose-6-phosphate dehydrogenase was measured to elucidate their role in coping with oxidative stress induced by metals at short- (14 h) and long- (8 days) term exposure. Results show that V. elodeae was more susceptible to the toxic effects induced by Cu and Zn than H. submersus, as indicated by more extensive inhibition of biomass production. Both metals, particularly Cu, induced oxidative stress in the two fungal species, as shown by the noticeable recovery of biomass production in the presence of an antioxidant agent. In both fungi, Cu induced a more severe disruption of plasma membrane integrity than Zn. Our studies on antioxidant defenses showed that catalase had a greater role alleviating stress induced by Zn and Cu than superoxide dismutase. Chronic metal stress also stimulated the production of NADPH, via the pentose phosphate pathway by increasing the activity of glucose-6-phosphate dehydrogenase. Our results suggest that the tolerance of aquatic hyphomycetes to Cu and Zn is associated with the ability of these fungi to initiate an efficient antioxidant defense system.     

Antioxidant biochemical responses to long-term copper exposure in Bathymodiolus azoricus from Menez-Gwen hydrothermal vent

Copper (Cu) is essential to various physiological processes in marine organisms. However, at high concentrations this redox-active transition metal may enhance the formation of reactive oxygen species (ROS) and subsequently initiate oxidative damage. High concentrations of Cu may increase oxidative damage to lipids, proteins and DNA. Bathymodiolus azoricus is a Mytilid bivalve very common in hydrothermal environments near the Azores Triple Junction continuously exposed to high metal concentrations, including Cu, emanating from the vent fluids. The knowledge of antioxidant defence system and other stress related biomarkers in these organisms is still scarce. The aim of this work was to study the effect of Cu (25 microg l(-1); 24 days exposure; 6 days depuration) on the antioxidant stress biomarkers in the gills and mantle of B. azoricus. The expression of stress related biomarkers was tissue-dependent and results suggest that other factors than metal exposure may influence stress biomarkers, since little variation in antioxidant enzymes activities, MT concentrations, LPO and total oxyradical scavenging capacity (TOSC) occurred in both control and Cu-exposed mussels. Moreover, there is a general tendency for these parameters to increase with time, in both control and Cu-exposed mussels, suggesting that reactive oxygen species (ROS) formation is not metal dependent, and may be related with poor physiological conditions of the animals after long periods in adverse conditions compared to those in hydrothermal environments.     

Exposure to polycyclic aromatic hydrocarbons, arsenic and environmental tobacco smoke, nutrient intake, and oxidative stress in Japanese preschool children

The association between oxidative stress and exposure to environmental chemicals was assessed in a group of Japanese preschool children. The concentrations of 8-hydroxy-2′-deoxyguanosine (8-OHdG), 1-hydroxypyrene (1-OHP), inorganic arsenic (iAs) and monomethylarsonic acid (MMA), and cotinine in spot urine samples, collected from 134 children (3-6 yrs) from a kindergarten in Kanagawa, Japan, were measured as biomarkers of oxidative stress or exposure to environmental chemicals. For 76 subjects of the 134, intakes of anti-oxidant nutrients (vitamins A, C, and E, manganese, copper, zinc and selenium (Se)) were estimated from a food consumption survey carried out 2-4 weeks after urine sampling and by urine analysis (Se). The median (min-max) creatinine-corrected concentrations of urinary biomarkers were 4.45 (1.98-12.3), 0.127 (0.04-2.41), 4.78 (1.18-12.7), and 0.62 (< 0.6-19.0) μg/g cre for 8-OHdG, 1-OHP, iAs + MMA, and cotinine, respectively. Multiple regression analysis was carried out using 8-OHdG concentration as a dependent variable and urinary biomarkers of exposure and Se intake, intakes of vitamins and biological attributes of the subjects as independent variables. To explain 8-OHdG concentrations, intake of vitamin A and age were significant variables with negative coefficients, while 1-OHP concentration had a positive coefficient. These results indicated that oxidative stress of children is affected by chemical exposure at environmental levels, by nutrient intake and by physiological factors in a complex manner. On the other hand, unstable statistical results due to sub-grouping of subject, based on the availability of food consumption data, were found: the present results should further be validated by future studies with suitable research design.     

Speciation of lead, copper, zinc and antimony in water draining a shooting range—Time dependant metal accumulation and biomarker responses in brown trout (Salmo trutta L.)

The speciation of Pb, Cu, Zn and Sb in a shooting range run-off stream were studied during a period of 23 days. In addition, metal accumulation in gills and liver, red blood cell ALA-D activity, hepatic metallothionine (Cd/Zn-MT) and oxidative stress index (GSSG/ tGSH levels) in brown trout (Salmo trutta L.) exposed to the stream were investigated. Fish, contained in cages, were exposed and sampled after 0, 2, 4, 7, 9, 11 and 23 days of exposure. Trace metals in the water were fractionated in situ according to size (nominal molecular mass) and charge properties. During the experimental period an episode with higher runoff occurred resulting in increased levels of metals in the stream. Pb and Cu were mainly found as high molecular mass species, while Zn and Sb were mostly present as low molecular mass species. Pb, Cu and Sb accumulated on gills, in addition to Al origination from natural sources in the catchment. Pb, Cu and Sb were also detected at elevated concentration in the liver. Blood glucose and plasma Na and Cl levels were significantly altered during the exposure period, and are attributed to elevated concentrations of Pb, Cu and Al. A significant suppression of ALA-D was detected after 11 days. Significant differences were detected in Cd/Zn-MT and oxidative stress (tGSH/GSSG) responses at Day 4. For Pb the results show a clear link between the HMM (high molecular mass) positively charged Pb species, followed by accumulation on gills and liver and a suppression in ALA-D. Thus, high flow episodes can remobilise metals from the catchment, inducing stress to aquatic organisms.     

Evidence of neuroendocrine disruption in freshwater mussels exposed to municipal wastewaters

The purpose of this study was to test the hypothesis that exposure to municipal effluents can disrupt the neuroendocrine system in Elliptio complanata freshwater mussels. The capacity of ozonation to mitigate these effects was also examined. Mussels were exposed for 14 days to a continuous flow of increasing concentrations of the effluent before and after ozonation. Neuroendocrinal effects were examined by tracking changes in acetylcholinesterase, glutamate, gamma-aminobutyrate, serotonin, dopamine and their respective adenylcyclase activities in synapse membranes, monoamine oxidase and vitellogenin-like proteins. Oxidative stress and damage were examined by superoxide dismutase and lipid peroxidation, respectively, in the visceral tissues. The results revealed that the exposure of freshwater mussels increased the levels of vitellogenin-like proteins in both the primary-treated and ozonated effluents, dopamine and glutamate, and decreased the turnover of the neurostimulant acetylcholine. Moreover, these endpoints were significantly correlated with oxidative stress and damage. A canonical analysis of the responses revealed that dopamine and the neuroexcitatory neuromediators-acetylcholesterase and glutamate-were the endpoints more strongly related with oxidative stress and damage. Mussel morphology and estrogenic biomarkers (vitellogenin-like proteins, gonad lipid stores) were also significantly related, albeit to a lesser extent, to oxidative stress and damage. In general, ozone treatment was not sufficient to mitigate the observed neuroendocrinal effects in freshwater mussels. We conclude that the continuous exposure of freshwater mussels to municipal wastewater effluents leads to neuroendrocinal alterations and to oxidative stress.     

Oxidative stress responses of Daphnia magna exposed to TiO2 nanoparticles according to size fraction

Size is one of important factors determining titanium dioxide nanoparticle (TiO₂ NP) toxicity since penetration is eased with decreasing particle size and bioavailability is increased. The effect of particle size on oxidative stress against titanium dioxide nanoparticle (TiO₂ NP) exposure to Daphnia magna was investigated with both acute and chronic toxicity tests. Experiments on biochemical responses, repeatedly performed after size fractionation of the NPs using filtration, focused on the activities of four antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), and glutathione-S-transferase (GST). In the chronic bioassay, the mortality was significantly increased at TiO₂ NP concentrations of 5 and 10 mg/L; however, no reduction of the reproduction ability was observed. Biochemical measurements showed that TiO₂ NP exposure significantly increased the antioxidant enzyme activities in D. magna. CAT, GPX and GST, but not SOD, showed a concentration-dependent increase. In terms of size fraction, particles ranging from 400 to 800 nm exhibited an increase of antioxidant enzyme activities in GST and GPX. These biochemical level observations suggested that TiO₂ NP toxicity was mediated by reactive oxygen species (ROS) generation via oxidative stress in D. magna. The increased mortality at the concentration of 5 mg/L in the chronic bioassay was attributed to accumulated TiO₂ NPs in the intestine of D. magna, which might induce effects such as oxidative stress relating to the induction of antioxidant enzymes.     

Organ specific antioxidant responses in golden grey mullet (Liza aurata) following a short-term exposure to phenanthrene

Phenanthrene (Phe) is among the most abundant and ubiquitous polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment as a result of human activities. Even so, the knowledge about its impact on fish health is still limited. In this study, the teleost Liza aurata was exposed to 0.1, 0.3, 0.9 and 2.7 µM Phe concentrations during 16 h. Enzymatic antioxidants such as selenium dependent glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and catalase (CAT), as well as a non-enzymatic antioxidant (glutathione — GSH) were quantified in three target organs — gill, kidney and liver. The lipid peroxidation (LPO) was also assessed as a marker of oxidative damage. GPx activity was decreased in gill (0.1 and 0.9 µM), whereas in the liver it was increased (0.3-2.7 µM). GST activity was decreased in kidney (0.3-2.7 µM) and CAT activity was increased in gill after 0.9 µM exposure. GSH content was significantly increased in gill by the lowest concentration and in liver by all Phe concentrations. Despite the antioxidant defense responses, LPO increased in gill (0.3-2.7 µM), kidney (0.1 µM) and liver (0.1 and 2.7 µM). These results revealed organ specific antioxidant defenses depending on the Phe concentration. Liver demonstrated a higher adaptive competence expressed as antioxidant defenses activation, namely GSH and GPX. The lower vulnerability of the kidney to oxidative damage (compared to gill and liver) seems to be related to its higher antioxidant basal levels. Globally, current data highlight the Phe potential to induce oxidative stress and, consequently, to affect the well-being of fish.     

Acute effects of Benzo[a]pyrene, anthracene and a fuel oil on biomarkers of the common goby Pomatoschistus microps (Teleostei, Gobiidae)

The objective of this study was to investigate the effects of two different PAHs and a complex petrochemical mixture on the common goby, Pomatoschistus microps, using selected biomarkers as effect criteria. Benzo[a]pyrene (BaP) and anthracene were used as reference substances, while the water accommodated fraction of #4 fuel-oil (#4 WAF) was used as an example of a petrochemical mixture. P. microps was used since it is both a suitable bioindicator and a good test organism. Groups of fish were exposed to different concentrations of each of the test substances for 96 h and the activities of several enzymes commonly used as biomarkers were determined at the end of the bioassays. All the substances inhibited P. microps acetylcholinesterase (AChE) indicating that they have at least one mechanism of neurotoxicity in common: the disruption of cholinergic transmission by inhibition of AChE. An induction of lactate dehydrogenase (LDH) activity was found in fish exposed to BaP or to anthracene, suggesting an increase of the anaerobic pathway of energy production. On the contrary, inhibition of LDH was found in fish exposed to #4 WAF, suggesting a distinct effect of the mixture. An induction of P. microps glutathione S-transferase (GST) activity was found in fish exposed to BaP or to #4 WAF, while an inhibition was observed after exposure to anthracene. These results suggest that GST is involved in the detoxification of BaP and #4 WAF, but not of anthracene. All the substances increased catalase activity and isolated PAHs also increased superoxide dismutase, glutathione reductase and glutathione peroxidase activities, while #4 WAF did not cause significant alterations on these enzymes. These results suggest that all the substances may induce oxidative stress on P. microps, with BaP and anthracene apparently having more oxidative stress potential than #4 WAF.     

Interactions between endogenous and dietary antioxidants against Pb-induced oxidative stress in wild ungulates from a Pb polluted mining area

Certain physiologic disorders, attributed to lead (Pb) exposure are related to the generation of oxidative stress. Organisms rely on a complex antioxidant system, composed of endogenously produced compounds such as glutathione (GSH), superoxide dismutase (SOD) and GSH peroxidase (GPX); and dietary antioxidants such as vitamins A and E. The aim of this work was to study the interactions between both groups of antioxidants and to evaluate their role in fighting Pb-induced oxidative stress in wild ungulates living in a Pb mining area. We studied red deer (n = 54) and wild boar (n = 60) from mining and control sites. Liver Pb, copper (Cu) and selenium (Se) levels were measured in liver and bone. Levels of GSH, oxidized GSH (GSSG), lipid peroxidation (TBARS), α-tocopherol, free retinol and retinyl esters, and the activities of SOD and GPX were measured in liver. Wild boar and red deer from the mining sites had higher bone (geometric means: 7.36 vs. 1.23 μg/g dw for boar; and 0.46 vs. 0.11 μg/g dw for deer) and liver Pb levels (0.81 vs. 0.24 μg/g dw for boar; and 0.35 vs. 0.11 μg/g dw for deer) than the controls. Pb exposure in deer was associated with lower GSH, α-tocopherol and retinyl esters, and higher free retinol and TBARS. A similar effect on vitamin A balance was observed in wild boar, but this was accompanied with an increase in GSH and α-tocopherol. GPX activity and Se levels were higher in wild boar (mean in controls: 670 IU/mg protein and 1.3 μg/g dw, respectively) than in red deer (150 IU/mg protein and 0.3 μg/g). These differences may indicate that red deer is more sensitive to Pb-induced oxidative stress than wild boar. Both endogenous and nutritional antioxidants may be negatively affected by Pb exposure, and their interactions are essential to fight against Pb-mediated oxidative damage.     

The effect of irrigation on tile sediment transport in a headwater stream

A field-scale no-till corn plot (120 m x 90 m) located on a tile drained silt loam soil near Kintore, Ontario was irrigated with 2.5 cm of water over a 3 h period to examine the effects of irrigation on tile sediment transport in a headwater stream. Flow characteristics and the composition, concentration and size distribution of suspended solids were measured at the tile outlet, an upstream reference site and three sites located downstream of the tile drain. Results show that tile sediments at the study site are fine-grained (D50 approximately 5.0 microm) and consist primarily of quartz, anorthite/albite, dolomite and calcite. Sediment concentrations in tile effluent increased from 8 to 57 mg L(-1) after 1.5 h of irrigation and reached a maximum of 72 mg L(-1). The sediment yield from the tile drain for the irrigation event was 4.6 kg ha(-1). An unsteady, mobile boundary flow model (MOBED) was used to predict flow characteristics in the stream. According to the MOBED model, bed shear stress in the stream was approximately 6 N m(-2). This value is significantly greater than the critical shear stress for complete suspension of 1 N m(-2) for tile sediments as determined from laboratory experiments using a rotating circular flume. Grain size distributions of suspended solids in the stream were close to the dispersed size distribution because of the high shear stress in the receiving stream.     

Adaptation Effects In The 70Th Generation Of Mice From Radionuclide-Polluted Territories In The South Urals,RUSSIA

Male Microtus arvalis mice from radionuclide-polluted territories in the South Urals ( 90 Sr activity of ground - 0.2 Ci/km 2 , 2 Ci/km 2 , 500 Ci/km 2 , 800 Ci/km 2 ) were investigated. The 90 Sr content in a mouse skeleton was determined. On intensification of protein and carbohydrate enzymes, an increase of total antioxidant activity and a reduction of lipid peroxidation processes were detected. These are the adaptation effects in the liver of Microtus arvalis mice, which are the 70th generation of animals exposed to long-term irradiation.