Juvenile sea bass biotransformation, genotoxic and endocrine responses to beta-naphthoflavone, 4-nonylphenol and 17 beta-estradiol individual and combined exposures

Juvenile sea bass, Dicentrarchus labrax L., were exposed during 2, 4, 8, and 24 h to 0.9 microM beta-naphthoflavone (BNF), 131 nM 17 beta-estradiol (E(2)), 4.05 microM 4-nonylphenol (NP), as well as to BNF combined either to E(2) or NP (maintaining the previous concentrations). Liver cytochrome P450 content (P450), ethoxyresorufin-O-deethylase (EROD), and glutathione S-transferase (GST) activities were measured in order to evaluate biotransformation responses. Genotoxicity was assessed as erythrocytic nuclear abnormalities (ENA) frequency. The effects on endocrine function were evaluated as plasma cortisol and glucose. Cortisol was not affected by xeno/estrogens tested, either in single exposure or mixed with BNF. Nevertheless, the intermediary metabolism was affected since glucose concentration increased after 4 h exposure to E(2), and after all BNF+NP exposure lengths. Moreover, a synergism between BNF and NP was thoroughly demonstrated, whereas a sporadic antagonistic interaction was found at 4 h BNF + E(2) exposure. Liver EROD and GST activities were not significantly altered by single E(2) or NP exposure. However, both compounds were able to induce EROD activity in the presence of BNF. NP single exposure was able to significantly increase liver P450 content, while its mixture with BNF displayed an antagonistic interference. Considering the xeno/estrogens single exposures, only NP induced an ENA increase; however, both mixtures (BNF + E(2) and BNF + NP) displayed genotoxic effects. Fish responses to mixtures of xenobiotics are complex and the type of interaction (synergism/potentiation or antagonism) in a particular mixture can vary with the evaluated biological response.     

Anguilla anguilla L. oxidative stress biomarkers responses to copper exposure with or without beta-naphthoflavone pre-exposure

The redox cycling of heavy metals as well as their interactions with organic pollutants is a major contributor to the oxidative stress resulting from aquatic pollution. Therefore, in order to evaluate beta-naphthoflavone (BNF), Cu and BNF/Cu-induced oxidative stress with single and subsequent exposures, research was carried out in European eel (Anguilla anguilla L.). Eel gill and kidney oxidative stress biomarker responses such as lipid peroxidation (LPO), glutathione peroxidase (GPX), catalase (CAT), glutathione S-transferase (GST) and total reduced glutathione (GSH) to a single 24 h exposure to two copper concentrations (Cu-1 microM, 2.5 microM) and BNF (2.7 microM) with or without 24 h BNF (2.7 microM) pre-exposure were investigated. Cu exposure alone showed a significant gill GST increase at the lowest concentration and GSH content decrease for the highest concentration. Double BNF exposure in gill demonstrated a significant increase in LPO, CAT, GPX and GST, as well as a decrease in GSH content. However, in sequential BNF/Cu exposures, only the highest Cu concentration exhibited a significant increase in LPO and GSH as well as a decrease in GPX (vs. BNF + CW). In kidney, Cu exposure alone showed a significant CAT and GSH contents decrease for both concentrations, and at highest concentration in GPX; as well as GST increase at the lowest concentration. Double BNF exposure showed a significant increase in LPO and GST. Nevertheless, in sequential BNF/Cu exposures, both concentrations exhibited a significant increase in LPO and decrease in GSH contents. Moreover, LPO was also increased significantly in comparison to BNF+CW and the equivalent Cu exposures without BNF pre-exposure. Concerning GPX, a significant increase was observed at highest Cu concentration. In GST, a significant decrease at the lowest Cu concentration and increase at the highest Cu concentration was observed. Summarizing, a simple copper or BNF exposures have no ability to induce LPO in both gill and kidney. However, double BNF exposure induced LPO in both organs and sequential BNF/Cu exposures potentiated the risk of peroxidative damage occurrence in both organs. BNF/Cu interference on antioxidant responses differs between the studied organs. In gill, antagonistic effects were denoted with probable reflex in terms of peroxidative damage increase. In kidney, BNF pre-exposure prevented CAT and GPX inhibition by copper; though, no advantage of this effect was perceptible as defence against LPO generation. Considering BNF as a surrogate for a PAH and the detected interactions with copper, as well as the likelihood that these effects would be observed in polluted ecosystems, current results demonstrate their relevance to actual ecological exposures contributing to a better knowledge on oxidative stress mechanisms in fish.     

Cytochrome P4501A, genotoxic and stress responses in golden grey mullet (Liza aurata) following short-term exposure to phenanthrene

This study represents a first approach to short-term effects of phenanthrene (Phe) in fish. The teleost Liza aurata was exposed to 0.1-2.7microM Phe during 16h. CYP1A induction was assessed as liver ethoxyresorufin-O-deethylase (EROD) activity. Genotoxicity was evaluated in gill and liver as DNA integrity (by alkaline unwinding), whereas in blood the erythrocytic nuclear abnormalities (ENA) frequency was determined. Stress responses were determined as cortisol, glucose and lactate plasma levels. Liver EROD activity was significantly increased by Phe 0.3-2.7microM. Phe genotoxicity in gill was not found, whereas liver DNA integrity significantly decreased after exposure to Phe 0.1 and 0.9microM demonstrating its genotoxicity which did not correlate with liver CYP1A induction. Phe genotoxicity in blood was demonstrated by a significant ENA increase from 0.1 up to 2.7microM. In terms of stress responses, plasma cortisol was significantly increased by Phe 0.3-2.7microM, though plasma glucose was only significantly increased by Phe 0.9 and 2.7microM. The Phe observed effects on L. aurata detected at different levels demonstrate a physiological unbalance and a probable ecological risk to ichthyofauna.     

Glutathione-dependent resistance of the European eel Anguilla anguilla to the herbicide molinate.

Eels of species Anguilla anguilla were exposed to 5/4 LC50 (41.8 mg/l) of the herbicide molinate for 96 h in a time to death (TTD) test. Glutathione content (GSx, GSH, GSSG), glutathione reductase (GR) and gamma-glutamyl transpeptidase (gamma-GT) activities were determined in the liver and muscle tissues of dead and surviving (intoxicated) animals and compared to control values (non-exposed eels). TTD was positively correlated to hepatic GSH, GSH:GSSG ratio, hepatic and muscular GR, but negatively correlated to muscular GSH, which was severely depleted. Furthermore, glutathione and enzyme activities were intercorrelated, especially GSH and GR. These results indicate that eels which were able to induce GR activity, increase GSH and maintain the GSH:GSSG ratio in the liver showed an extended survival under the oxidative stress generated by molinate than those that lost glutathione homeostasis.     

Pesticides and Essential Minerals Modify Endogenous Antioxidants and Cytochrome P450 in Tissues of Rats

Two experiments were conducted in male Sprague Dawley (SD) rats (175–200 g) to determine changes in the activities of endogenous antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPX), cytochrome P450 (ethoxyresorufin deethylase; EROD) and concentrations of glutathione (GSH) in the blood, liver, and small intestinal mucosa (IM). In both experiments, six rats/group were fed diets based on the AIN-93M diet (Control) or the same modified to contain either 500 mg calcium (Low Ca), 7 mg Zn (Low Zn): 2 mg copper (Low Cu), 60 mg zinc (High Zn) or 12 mg copper (High Cu) in the following combination: Control, LCa/LZn, LCa/LZn/LCu, or HZn/HCu, with and without a pesticide mixture containing acephate, endosulfan, and thiram at 25% LD₅₀ for four or two weeks. Pesticides decreased feed intake and weight gain in all groups by 28%. Erythrocyte SOD was higher than control in the HZn/HCu group and in the LCa/LZn/LCu and HZn/HCu groups with pesticide (P# 0.05). Plasma GPX declined by more than 55% in all the groups with and without pesticides compared to the control. The LCa/LZn/LCu and HZn/HCu diets with and without pesticides reduced GPX in the IM by up to 88%, 40%, and 74%, respectively, than the control. Plasma GSH was about 20% higher than the control in most groups with and without pesticides in the diet. Liver and IM GSH were higher than the control in the HZn/HCu group, whereas IM GSH concentrations were lower than the control in the LCa/LZn and LCa/LZn/LCu groups (P#0.05). All three experimental diets with and without pesticides had a significant effect on liver EROD activity (P#0.05). The results indicate that endogenous antioxidants and EROD were independently modified by dietary zinc and copper levels and pesticides.     

Pesticides and essential minerals modify endogenous antioxidants and cytochrome P450 in tissues of rats

Two experiments were conducted in male Sprague Dawley (SD) rats (175-200 g) to determine changes in the activities of endogenous antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPX), cytochrome P450 (ethoxyresorufin deethylase; EROD) and concentrations of glutathione (GSH) in the blood, liver, and small intestinal mucosa (IM). In both experiments, six rats/group were fed diets based on the AIN-93M diet (Control) or the same modified to contain either 500 mg calcium (Low Ca), 7 mg Zn (Low Zn): 2 mg copper (Low Cu), 60 mg zinc (High Zn) or 12 mg copper (High Cu) in the following combination: Control, LCa/LZn, LCa/LZn/LCu, or HZn/HCu, with and without a pesticide mixture containing acephate, endosulfan, and thiram at 25% LD50 for four or two weeks. Pesticides decreased feed intake and weight gain in all groups by 28%. Erythrocyte SOD was higher than control in the HZn/HCu group and in the LCa/LZn/LCu and HZn/HCu groups with pesticide (P#0.05). Plasma GPX declined by more than 55% in all the groups with and without pesticides compared to the control. The LCa/LZn/LCu and HZn/HCu diets with and without pesticides reduced GPX in the IM by up to 88%, 40%, and 74%, respectively, than the control. Plasma GSH was about 20% higher than the control in most groups with and without pesticides in the diet. Liver and IM GSH were higher than the control in the HZn/HCu group, whereas IM GSH concentrations were lower than the control in the LCa/LZn and LCa/LZn/LCu groups (P#0.05). All three experimental diets with and without pesticides had a significant effect on liver EROD activity (P#0.05). The results indicate that endogenous antioxidants and EROD were independently modified by dietary zinc and copper levels and pesticides.     

Atrazine promotes biochemical changes and DNA damage in a Neotropical fish species

The effects of Atrazine, an herbicide used worldwide and considered as a potential contaminant in aquatic environments, were assessed on the Neotropical fish Prochilodus lineatus acutely (24 and 48 h) exposed to 2 or 10 μg L⁻¹ of atrazine by using a set of biochemical and genetic biomarkers. The following parameters were measured in the liver: activity of the biotransformation enzymes ethoxyresorufin-O-deethylase (EROD) and glutathione S transferase (GST), antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), content of reduced glutathione (GSH), generation of reactive oxygen species (ROS) and occurrence of lipid peroxidation (LPO); in brain and muscle the activity of acetylcholinesterase (AChE) and DNA damage (comet assay) on erythrocytes, gills and liver cells. A general decreasing trend on the biotransformation and antioxidant enzymes was observed in the liver of P. lineatus exposed to atrazine; except for GR, all the other antioxidant enzymes (SOD, CAT and GPx) and biotransformation enzymes (EROD and GST) showed inhibited activity. Changes in muscle or brain AChE were not detected. DNA damage was observed in the different cell types of fish exposed to the herbicide, and it was probably not from oxidative origin, since no increase in ROS generation and LPO was detected in the liver. These results show that atrazine behaves as enzyme inhibitor, impairing hepatic metabolism, and produces genotoxic damage to different cell types of P. lineatus.     

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp (Cyprinus carpio)

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps (Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 microg l-1 for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid- reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity.     

The redox state and activity of superoxide dismutase classes in Arabidopsis thaliana under cadmium or copper stress

The redox state of glutathione and ascorbate as well as the activity of superoxide dismutase classes were determined in leaves of Arabidopsis thaliana grown for seven days in the nutrient solution containing 0, 5 and 50 microM Cd or Cu excess. A decrease in GSH/GSSG ratio was found in plants under Cd and Cu stress. In the plants exposed to Cu stress the activity of all SOD classes increased. However, in the plants treated with Cd the activity of FeSOD and MnSOD was elevated, but CuZnSOD activity was diminished in comparison with control. In these plants the activity of SOD classes was dependent on both the GSH/GSSG and AA/DHA ratios, while in those exposed to Cu excess - on the GSH/GSSG ratio. Differences were shown in the changes both in redox state and activity of SOD classes caused by the metals differing in physiochemical properties. Moreover, relationships between changes in SOD class activities and ROS levels were discussed.     

Vitamin and thyroid status in arctic grayling (Thymallus arcticus) exposed to doses of 3,3',4,4'-tetrachlorobiphenyl that induce the phase I enzyme system

Induction of phase I biotransformation enzymes is recognized as a hallmark response in fish exposed to coplanar PCBs. Depletions of vitamins A and E and disrupted thyroid hormone and glandular structure secondary to this induction have not yet been examined in an arctic fish species. Arctic grayling were exposed to a single oral dose of 0 (control), 10, 100 or 1000 ng 3,3',4,4'-tetrachlorobiphenyl (TCB) g(-1) bodyweight, a contaminant found in most arctic fish. After 30 and 90 days of exposure, TCB concentrations in tissues, hepatic phase I activity (as ethoxyresorufin-O-deethylase (EROD)), plasma and tissue vitamin A and E concentrations, plasma thyroid hormone levels and thyroid glandular structure were examined. Total plasma osmolality, as an indicator of overall fish health was also monitored. TCB recovery in tissues was low and extremely variable, making comparisons between intended dose groups inappropriate. Therefore, correlation analysis between actual recovered TCB concentrations and biochemical responses was employed. Hepatic EROD activity correlated strongly with liver TCB concentrations. Liver concentrations of vitamin A were altered as a function of TCB concentrations and EROD activity, but plasma vitamin A status was not affected. Vitamin E was depleted by TCB accumulation in blood and EROD induction in liver of males only at 90 days postexposure. Thyroid hormones status and glandular structure were not affected by the short duration TCB exposures used in this experiment. TCB concentrations were correlated with an elevation in plasma osmolality. Results from this experiment indicate that the vitamin status and osmoregulation of arctic grayling exposed to TCB can be compromised. Further studies of field populations exposed to this type of contaminant are warranted.     

Exposure to low doses of endosulfan and chlorpyrifos modifies endogenous antioxidants in tissues of rats

Two experiments were conducted in male SD rats (225-250 g) to determine changes in the activities of endogenous antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and concentrations of glutathione (GSH) in tissues after exposure to low doses of endosulfan and chlorpyrifos using a whole body exposure technique. In both experiments, 6 rats/group were exposed 3 hr/day, 5 days/week for 30 days to: 0 (control), 5, 10, 20, 40 and 60% of LD50 of either pesticide in 50% ethanol; actual concentrations were: endosulfan = 0, 0.5, 1.0, 2.0, 4.0, 6.0 mg/250 g body weight; chlorpyrifos = 0, 1.9, 3.8, 7.6, 15.2, and 22.8 mg/250 g body weight. Endosulfan decreased erythrocyte SOD by 21% in all groups and chlorpyrifos increased SOD by 18% in groups 40 and 60. Liver SOD was 12%-20% lower after endosulfan exposure; lung SOD was altered: endosulfan decreased activity by 21% and 51% and chlorpyrifos by 58 and 75% in the 40 and 60 groups, respectively (P < or = 0.05). Both pesticides increased plasma GPX activity at lower levels and reduced it by 26% and 19% in groups 40 and 60, respectively (P < or = 0.05). Liver GPX increased in the 60 group and lung GPX declined between 20% and 38% after endosulfan exposure. GSH in the liver and lung: endosulfan reduced GSH by about 30% at lower levels and increased by 41% or 70% at higher levels; chlorpyrifos decreased GSH by 28-40% in 20 and 60 groups, respectively (P < or = 0.05). Exposure to low, increasing levels of endosulfan and chlorpyrifos can differentially modify endogenous antioxidants SOD, GPX and GSH, which may lead to the development of oxidative stress in some tissues.     

Effect of prochloraz fungicide on biotransformation enzymes and oxidative stress parameters in three-spined stickleback (Gasterosteus aculeatus L.)

The aim of this study was to characterize biomarker responses in three-spined sticklebacks exposed to prochloraz (Pcz). For this purpose, adult sticklebacks were exposed for 2 weeks to prochloraz at 0, 10, 50, 100 and 500 μg/L prior to one week of depuration in clean water. At days 7, 14 and 21, several hepatic biomarkers were measured including 7-ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), glutathione peroxidase (GPx), catalase (CAT), total glutathione (GSH) content and thiobarbituric acid reactive substances (TBARS). Pcz induced a transient increase of antioxidant enzymes and a depletion of glutathione content during the first 7 days of exposure. This study showed that EROD activity and antioxidants were disrupted in a transient manner. GST was rapidly induced in a dose-dependent manner and this induction was persistent and observed also after depuration. GST appeared as a valuable biomarker to assess the exposure to Pcz.     

Effect of prochloraz fungicide on biotransformation enzymes and oxidative stress parameters in three-spined stickleback (Gasterosteus aculeatus L.)

The aim of this study was to characterize biomarker responses in three-spined sticklebacks exposed to prochloraz (Pcz). For this purpose, adult sticklebacks were exposed for 2 weeks to prochloraz at 0, 10, 50, 100 and 500 microg/L prior to one week of depuration in clean water. At days 7, 14 and 21, several hepatic biomarkers were measured including 7-ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), glutathione peroxidase (GPx), catalase (CAT), total glutathione (GSH) content and thiobarbituric acid reactive substances (TBARS). Pcz induced a transient increase of antioxidant enzymes and a depletion of glutathione content during the first 7 days of exposure. This study showed that EROD activity and antioxidants were disrupted in a transient manner. GST was rapidly induced in a dose-dependent manner and this induction was persistent and observed also after depuration. GST appeared as a valuable biomarker to assess the exposure to Pcz.     

Effect of cadmium on free amino acid, glutathione and ascorbic acid concentrations in two barley genotypes (Hordeum vulgare L.) differing in cadmium tolerance

Hydroponic experiment was carried out to study the effect of three Cd levels on glutathione (GSH), free amino acids (FAA), and ascorbic acid (ASA) concentration in the different tissues of 2 barley cultivars with different Cd tolerance. Cadmium concentration in both roots and shoots increased with external Cd level, while biomass and ASA concentration declined, and Wumaoliuling, a Cd-sensitive genotype was more affected than ZAU 3, a Cd-tolerant genotype. The effect of Cd on GSH concentration was dose- and time-dependent. In the 5 d exposure, root GSH concentration increased in 0.5 microM Cd treatment compared with control, but decreased significantly in 5 microM Cd treatment, irrespective of genotypes. However, in the 10 d exposure, GSH concentration in all plant tissues decreased with increasing Cd levels in the culture medium, and Wumaoliuling was much more affected than ZAU 3. Cadmium treatment greatly altered FAA concentration and composition in plants. The effect of Cd on glutathione (Glu) concentration in roots varied with genotypes. ZAU 3 showed a steady increase in root Glu concentration in both 0.5 and 5 microM Cd treatments, while Wumaoliuling was decreased by 38.0% in 5 microM Cd treatment, compared with the control. The results indicate that GSH and ASA are attributed to Cd tolerance in barley plants, and the relative less reduction in GSH concentration in ZAU 3 under Cd stress relative to the control may account for its higher Cd tolerance.     

Evaluation of impact of PAH on a tropical fish, Oreochromis mossambicus using multiple biomarkers

Treatment of the widely occurring tropical cichlid, Oreochromis mossambicus with a pure polycyclic aromatic hydrocarbon (PAH), phenanthrene, induced a concentration-dependant formation of the enzyme, 7-ethoxyresorufin-O-deethylase (EROD). Concomittant increase (65-669%) in the activity of sorbitol dehydrogenase in the serum (SSDH) occurring with EROD induction denoted liver cell damage, which was more severe in fish exposed to lower concentrations (0.4-4 microg g-1) of the chemical. In O. mossambicus exposed to 25% refinery effluent liver damage associated with cell death was indicated by the twin analyses of SSDH and liver somatic index. Cell injury appeared to have occurred at low PAH concentrations due to inadequately induced phase II-related detoxification of metabolites. This was indicated by the nearly 33% higher activity of hepatic glutathione S-transferase (GST) in fish exposed to higher PAH concentrations as compared to low-exposure animals. Tilapia such as O. mossambicus were found to be eminently suited for biomonitoring in tropical coastal waters. A combination of EROD and serum sorbitol dehydrogenase activity measurements serves as an excellent tool for biomonitoring sublethal effects of PAH pollution in fish.     

Hydroxyl radical generation and oxidative stress in Carassius auratus liver as affected by 2,4,6-trichlorophenol

With Carassius auratus, one of the main economic fish species in Eastern China as test material, this paper studied the hydroxyl radical generation and oxidative stress in its liver under the effect of 2,4,6-trichlorophenol (2,4,6-TCP). Different doses of 2,4,6-TCP were injected intraperitoneally into the fishes, and the Electron paramagnetic resonance (EPR) spectra of hepatic free radicals, activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-s-transferase (GST), levels of reduced glutathione (GSH) and oxidized glutathione (GSSG), and malondialdehyde (MDA) contents were determined 24h after injection. The results showed that under the effects of 2,4,6-TCP, the generation of free radical that was considered to be hydroxyl radical increased significantly, the activities of antioxidant enzymes decreased, with CAT most strongly affected and followed by SOD and GST, the GSH level decreased significantly while GSSG level had little difference, resulting in a decreased GSH/GSSG ratio, and the MDA content increased significantly. All the test parameters showed that C. auratus was subjected to oxidative stress and damage when exposed to 2,4,6-TCP.     

Heavy metal exposure in large game from a lead mining area: Effects on oxidative stress and fatty acid composition in liver

The Pb mining area of the valley of Alcudia and the Sierra Madrona mountains (S. Spain) has been exploited intermittently for over 2100 years, since Roman occupation and up until the late 1900s. Red deer (n = 168) and wild boar (n = 58) liver and bone (metacarpus) were analyzed for Pb, Zn, Cu, Cd, As and Se. Lipid peroxidation, total and oxidized glutathione (GSH), superoxide dismutase (SOD), GSH peroxidase (GPX) and fatty acid composition were studied in liver of red deer. The concentrations of Pb in liver and bone of red deer and wild boar were higher in the mining area than in the control area, and higher in the wild boar than red deer, but well below the level associated with clinical signs of Pb poisoning. Liver levels of Cu, Cd and Se were also higher in red deer from the mining area. Red deer from the mining area had 39% less total GSH than in the control area. The percentage of docosahexaenoic acid in liver of red deer from the mining area was 16% lower than in the control area.     

Lipid peroxidation and antioxidant enzyme activity in different organs of mice exposed to low level of mercury

The effects of mercuric chloride (Hg) on lipid peroxidation (LPO), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione (GSH) levels in different organs of mice (CD-1) were evaluated. Mice were exposed (2 days/week) to 0.0 (control), 0.8 (low) and 8.0 (mid) and 80.0 (high) gHg/kg/day for 2 weeks. The high dose group was excluded from the study due to high mortality. LPO levels in kidney, testis and epididymus at low and mid doses; GR and GPx levels in testis at mid dose; SOD levels in brain and testis at both doses, liver and epididymus at mid dose; GSH levels in testis at both doses were significantly increased compared to their controls. However, the GR levels in kidney at both doses and in epididymus at mid dose; GPx levels in kidney and epididymus and SOD levels in kidney at both the doses; GSH levels in epididymus at mid dose were significantly decreased compared to their control. Body weight gain and food efficiency were significantly reduced (p<0.05) in mid dose. These results indicated that Hg treatment enhanced LPO in all tissues, but showed significant enhancement only in kidney, testis and epididymus suggesting that these organs were more susceptible to Hg toxicity. The increase in antioxidant enzyme levels in testis could be a mechanism protecting the cells against reactive oxygen species.     

The veterinary antibiotic oxytetracycline and Cu influence functional diversity of the soil microbial community

There are increasing concerns over the effects of veterinary antibiotics and heavy metals in agricultural soils. The widely used veterinary antibiotic oxytetracycline (OTC), Cu and their combination on soil microbial community function were assessed with the Biolog method. The microbial community was extracted from the soil and exposed to a 0.85% sodium chloride solution containing OTC (0, 1, 5, 11, 43, 109 and 217 microM), or Cu (0, 10, 20, 100 and 300 microM), or combination of the two pollutants (OTC 0, 5, 11 microM and Cu 0, 20 microM). Functional diversity, evenness, average well color development (AWCD) and substrate utilization decreased significantly with increasing concentrations of OTC or Cu (p < 0.005). The critical concentrations were 11 microM for OTC and 20 microM for Cu. The combination of OTC and Cu significantly decreased Shannon's diversity, evenness and utilization of carbohydrates and carboxylic acids compared to individual one of the contaminants. The antibiotic OTC and Cu had significant negative effects on soil microbial community function, particularly when both pollutants were present.     

LIPID PEROXIDATION AND ANTIOXIDANT ENZYME ACTIVITY IN DIFFERENT ORGANS OF MICE EXPOSED TO LOW LEVEL OF MERCURY

The effects of mercuric chloride (Hg) on lipid peroxidation (LPO), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione (GSH) levels in different organs of mice (CD-1) were evaluated. Mice were exposed (2 days/week) to 0.0 (control), 0.8 (low) and 8.0 (mid) and 80.0 (high) gHg/kg/day for 2 weeks. The high dose group was excluded from the study due to high mortality. LPO levels in kidney, testis and epididymus at low and mid doses; GR and GPx levels in testis at mid dose; SOD levels in brain and testis at both doses, liver and epididymus at mid dose; GSH levels in testis at both doses were significantly increased compared to their controls. However, the GR levels in kidney at both doses and in epididymus at mid dose; GPx levels in kidney and epididymus and SOD levels in kidney at both the doses; GSH levels in epididymus at mid dose were significantly decreased compared to their control. Body weight gain and food efficiency were significantly reduced (<0.05) in mid dose. These results indicated that Hg treatment enhanced LPO in all tissues, but showed significant enhancement only in kidney, testis and epididymus suggesting that these organs were more susceptible to Hg toxicity. The increase in antioxidant enzyme levels in testis could be a mechanism protecting the cells against reactive oxygen species.