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This study was conducted to determine the best combination of protein sources in diets for jundiá, based on growth, metabolism, and nutrient deposition. Five protein combinations were tested: casein + fish meal (control), casein + gelatin, casein + albumin, casein + albumin + fish meal, and albumin + fish meal, in diets containing 370 g Kg-1 of crude protein and 13.4 MJ Kg-1 of digestible energy. The fish (9.38 ± 0.12 g) were allocated in a water recirculation system at a density of 3.35 g L-1 per experimental unit and fed until apparent satiety for 40 days with the diets. The fish fed with the control diet had the highest final weight, specific growth rate, protein and feed efficiency ratio, protein retention, and best apparent feed conversion. On the other hand, fish that received casein + albumin and albumin + fish meal diets showed worse results in growth and body protein retention, low trypsin and chymotrypsin activity, and high intestinal amylase activity. Therefore, the combination referred to as control (casein + fish meal) conclusively provides the best rhythm for nutrient digestion and metabolism processes, enabling fish to reach greater growth and retention of body protein with low whole-fish fat content.

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The aim of this study was to evaluate the effects of dietary diphenyl diselenide [(PhSe)2] at different concentrations (1.5, 3.0, and 5.0 mg/kg) on growth, oxidative damage and antioxidant parameters in silver catfish after 30 and 60 days. Fish fed with 5.0 mg/kg of (PhSe)2 experienced a significant decrease in weight, length, and condition factor after 30 days and these parameters increased after 60 days. Thiobarbituric acid reactive substances (TBARS) and protein carbonyl (PC) decreased in the liver of silver catfish supplemented with (PhSe)2 after 30 days at all concentrations, while after 60 days these parameters decreased in liver, gills, brain, and muscle. Supplementation with (PhSe)2 induced a decrease in catalase (CAT) activity from liver only after 60 days of feeding. Superoxide dismutase (SOD) decreased at 5.0 mg/kg after 30 and 60 days and glutathione peroxidase (GPx) was enhanced at 1.5 and 3.0 mg/kg after 30 and 60 days. Silver catfish supplemented for 30 days showed a significant increase in liver glutathione S-transferase (GST) at 3.0 mg/kg, while after 60 days GST activity increased in liver at 1.5, 3.0, and 5.0 mg/kg and in gills at 3.0 and 5.0 mg/kg of (PhSe)2. After 30 days, non-protein thiols (NPSH) did not change, while after 60 days NPSH increased in liver, gills, brain, and muscle. In addition, ascorbic acid (AA) levels after 30 days increased in liver at three concentrations and in gills and muscle at 1.5 mg/kg, while after 60 days, AA increased at all concentrations in all and tissues tested. Thus, diet supplemented with (PhSe)2 for 60 days could be more effective for silver catfish. Although the concentration of 5.0 mg/kg showed decreased growth parameters, concentrations of 1.5 and 3.0 mg/kg, in general, decreased oxidative damage and increased antioxidant defenses.

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O presente trabalho teve como objetivo avaliar efeitos da inclusão de casca de soja em substituição ao feno de alfafa sobre o desempenho, características da carcaça e trato gastrointestinal e parâmetros bioquímicos de coelhos em fase de crescimento. Foram utilizados 30 coelhos da raça Nova Zelândia Branca, divididos igualmente em três tratamentos, compostos pela dieta experimental padrão (sem inclusão de casca de soja); e pelas dietas com 50% e 100% de substituição de alfafa por casca de soja nas respectivas rações experimentais. Concluiu-se que a casca de soja pode ser incluída em dietas para coelhos em crescimento, em substituição ao feno de alfafa em até 100% sem causar danos no desempenho nas características de carcaça e do trato gastrointestinal e parâmetros bioquímicos dos animais, durante a fase de crescimento. Porém, a utilização deste co-produto exige a necessidade de estudos mais aprofundados em virtude da escassez de dados.

This study aimed to evaluate the effects of inclusion of soybean hulls in the replacement of alfalfa hay on performance, of growing rabbits. A total of 30 rabbits of New Zealand White kind were divided into three treatments, experimental compounds in the pattern diet (without inclusion of soybean hulls), and the diets with 50% and 100% replacement of alfalfa by soybean hulls in their experimental diets. It was concluded that the soybean hulls can be included on replace of alfafa hulls up 100% in rabbits diets. However, the use of co-product in animal nutrition need more detailed studies because of the paucity of data.

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The objective of this study was to verify whether a commercial formulation of 2,4 dichlorophenoxyacetic acid [2,4-D dimethylamine salt (DMA)] affects the growth and biochemical parameters of silver catfish (Rhamdia quelen) after 90 days of exposure. The fish exposed to 0.5 or 2.0 mg/L of DMA presented exhibited decreased growth parameters. Glucose was reduced in the mucus layer at both concentrations, and the total protein level was increased at the highest concentration tested. Fish exposed to DMA showed reduced liver and kidney glycogen at both concentrations tested, while in the muscle, glycogen was reduced only at 2.0 mg/L. Glucose was increased in the liver and decreased in the muscle and kidney at both concentrations and was not altered in the plasma. Lactate was increased in all the tissues and decreased in the plasma. Protein levels were reduced in the liver and plasma at both concentrations, while in the muscle, it was decreased at a concentration of 2.0 mg/L. Levels of thiobarbituric acid-reactive substances were reduced in the liver and increased in the muscle at both concentrations and did not change in the brain. DMA increased catalase activity in the liver at both concentrations tested. The present study demonstrates the effects of long-term exposure to DMA. Some parameters could be used as toxicity indicators to identify the presence of DMA in an aquatic environment.

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The effects of glyphosate, a nonselective herbicide (1.0 or 5.0mg L-1) on digestive enzymes activity (stomach and intestine) were evaluated in juveniles of piava (Leporinus obtusidens) after 90 days of exposure. The activity of acid protease, trypsin, chymotrypsin and amylase increased with the increase of glyphosate concentration. These results indicate that glyphosate affects digestive enzyme activities in this species, and may be an indicator of poor nutrient availability when fish survive in herbicide-contaminated water.

Os efeitos do glifosato, um herbicida não seletivo (1,0 ou 5,0mg L-1), sobre a atividade de enzimas digestivas (estômago e intestino) foram avaliadas em juvenis de piava (Leporinus obtusidens) após 90 dias de exposição. A atividade da protease ácida, tripsina, quimiotripsina e amilase aumentaram com a elevação da concentração de glifosato. Esses resultados indicam que o glifosato afeta a atividade de enzimas digestivas nesta espécie e pode ser indicador da reduzida disponibilidade de nutrientes, quando peixes sobrevivem em água contaminada com este herbicida.

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Este estudo avaliou os efeitos da substituição parcial de farinha de peixe e farinha de carne e ossos por farelo de crambe, sobre o crescimento, enzimas digestivas e parâmetros bioquímicos no jundiá (Rhamdia quelen). Este coproduto agroindustrial foi incluído na alimentação de jundiás na forma in natura ou reduzido em antinutrientes, obtido após a aplicação de tratamento químico ao farelo. A inclusão desses ingredientes foi comparada ao tratamento controle (proteína baseada em farinhas de origem animal) durante nove semanas. Crescimento semelhante ao controle foi observado em peixes alimentados com farelo de crambe in natura ou tratado quimicamente na dieta. A inclusão do farelo in natura reduziu a atividade de protease ácida e colesterol plasmático, mas não alterou os parâmetros bioquímicos hepáticos. Menor concentração de glicogênio e glicose no fígado e aumento na aspartato aminotransferase foi encontrada nos peixes alimentados com farelo de crambe tratado, sinalizando uma condição de carência energética. A similar resposta no crescimento, aliada às leves alterações digestivas e metabólicas com o farelo de crambe in natura em relação ao farelo tratado, pode indicar que, no nível de inclusão utilizado, este ingrediente não necessita de um processo prévio para redução de antinutrientes.

This study evaluated the effects of partial replacement of fish meal and meat and bone meal by plant based meal from the biofuel production chain on growth, digestive enzymes and biochemical parameters in silver catfish, Rhamdia quelen. This agro-byproduct was included in the silver catfish feed as an in natura byproduct or in the reduced antinutrients form, obtained after applying chemical treatment to meal. The inclusion of these ingredients was compared to the control treatment (protein based in animal meal) during nine weeks. Growth similar to the control was observed in fish fed with in nature or treated chemically crambe meal in the diet. Inclusion of in natura crambe meal reduced acid protease activity and plasma cholesterol, but did not alter hepatic biochemical parameters. Lower glycogen and glucose concentration in the liver and increase in aspartate aminotransferase were found in fish fed treated crambe meal, signaling an energy deficiency condition. The similar growth response coupled to slight metabolic and digestive changes with in nature crambe meal in relation to the treated meal may indicate that in the inclusion level used this ingredient does not require prior reduction of antinutrients.

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Effects of carbofuran commercial formulation on oxidative stress parameters were studied in carps (Cyprinus carpio) exposed to 50µg/L for 7 and 30 days under rice field and laboratory conditions. Thiobarbituric acid reactive substance (TBARS) levels were increased in the brain of fish after 7 and 30 days under rice field and laboratory conditions. In the liver and muscle, TBARS levels increased after 7 and 30 days under laboratory conditions, whereas in rice field the levels increased only after 30 days. Protein carbonyl content in the liver increased after 7 and 30 days under both experimental conditions. Acetylcholinesterase (AChE) activity was decreased in the brain and muscle after 7 and 30 days under both experimental conditions evaluated. The superoxide dismutase (SOD) activity increased in the liver after 7 and 30 days under rice field condition, whereas under laboratory condition this enzyme increased only after 30 days. The catalase (CAT) activity in the liver decreased after 30 days under rice field condition, whereas no changes were observed under laboratory conditions. In rice field, glutathione S-transferase (GST) decreased after 7 days but increased after 30 days, whereas no change was observed in fish exposed to carbofuran under laboratory conditions. These results suggest that environmental relevant carbofuran concentrations may cause oxidative stress, affecting biochemical and enzymatic parameters on carps. Some parameters could be used as biomarkers to carbofuran exposure.

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The effects of Cu exposure on catalase (CAT) and acetylcholinesterase (AChE) activity, formation of thiobarbituric acid-reactive species (TBARS) and metabolic parameters were evaluated in silver catfish (Rhamdia quelen). The fish were exposed for 45 days to 0, 16 and 29 µg/L Cu. The fish that were exposed to Cu exhibited lower TBARS levels in the muscle and higher TBARS levels in the liver. They also showed lower CAT activity in the liver and lower AChE activity in the brain and muscle. Higher glucose and lactate and lower protein plasma levels were observed in the fish exposed to Cu. The changes in the hepatic metabolic parameters were Cu concentration dependent. In the muscle, lower glycogen and higher lactate levels were observed in the fish exposed to Cu. Alterations in the metabolic parameters showed a preference for the anaerobic pathway of energy production and liver protein catabolism to supply the energy demand.

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Changes in carbohydrate and protein metabolism were studied in silver catfish Rhamdia quelen exposed to cadmium (0; 0.236 or 0.414 mg/L) during 7 and 14 days. After exposure time the fish were exposed to recovery period (water without cadmium), during 7 and 14 days. Different alterations in the metabolic parameters were observed such as an increase in lactate, protein, amino acid and ammonia levels as well as a reduction in glucose values after the exposure periods in liver. In muscle, glycogen and glucose values enhanced after cadmium exposure at both concentrations for 7 days; however, at 0.414 mg/L cadmium, protein levels decreased while amino acids and ammonia levels enhanced. An increase in the lactate values was found in plasma after 7 days of exposure and a reduction in the lactate, glucose and protein levels occurred after 14 days of exposure. Results indicated that the metabolic alterations after cadmium exposure were dependent on the tissue type and exposure time. Cadmium exposure for 14 days and recovery period also of 14 days seem to be less harmful to the liver and muscle. However, even after recovering from some changes, fish health may be affected making them more sensitive to some environmental changes.

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Neste trabalho, avaliaram-se as concentrações de ácido fítico, fenóis totais e taninos totais em farelos de canola, girassol e soja, submetidos a diferentes tratamentos químicos, destinados para alimentação de peixes. Os tratamentos foram: A: água acidificada; EMA: etanol P.A. + metanol P.A. + água, na proporção 45:45:10; ET: etanol P.A. acidificado; ETA: etanol P.A. + água acidificada na proporção 70:30; AE: água acidificada e Etanol P.A. utilizados separadamente. No farelo de canola, os tratamentos EMA, ET e ETA aumentaram a concentração de ácido fítico. Os tratamentos AE e ETA foram mais eficientes na remoção de fenóis totais. O teor de taninos foi reduzido em todos os tratamentos, com destaque para ET, ETA e AE. Para o farelo de girassol, os teores de ácido fítico foram reduzidos com os tratamentos A e AE. O tratamento AE removeu a maior quantidade de fenóis totais e taninos totais. Para o farelo de soja, o tratamento A foi o único a reduzir o teor de ácido fítico. O tratamento AE foi mais eficiente na remoção de fenóis totais e taninos totais para esse farelo. O tratamento AE representa a melhor alternativa para extração desses antinutrientes para os farelos de canola, girassol e soja.

The phytic acid, phenolic compounds and total tannins contents of canola, sunflower and soybean meals subjected to different chemical treatments were evaluated in this study, aiming its inclusion in fish diets. The treatments were: a) A: acidified water (pH 1.0); b) EMA: ethanol (absolute) + methanol (absolute) + water, (45:45:10 ratio); c) ET: acidified ethanol (absolute) (pH 1.0); d) ETA: ethanol (absolute) + water (70:30 ratio) pH 1.0; e) AE: acidified water (pH 1.0) + ethanol (absolute) used separately. For canola meal, phytic acid content raised when treatments EMA, ET and ETA were used. Treatments AE and ETA were more efficient for reducing phenolic compounds. Total tannins showed reduction under all treatments, but ET, ETA, and AE were more effective. For sunflower meal, A and AE reduced phytic acid content, while the other treatments caused an increase in this antinutrient. Total phenols and tannins were most reduced under AE treatment. For soybean meal, treatment A was the only which reduced phytic acid content. Treatment AE was the best on reducing total phenols and tannins for soybean meal. Treatment AE represents the best alternative for reducing phytic acid, total phenols and total tannins of canola, sunflower and soybean meals.

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O objetivo deste estudo foi analisar a influência da adição de farinha de resíduos de jundiá (Rhamdia quelen) na dieta de exemplares desta espécie sobre a bioquímica plasmática, parâmetros hepáticos e digestivos. No experimento I (EXP I), compararam-se dietas com 30% de farinha de carne e ossos suína (FCO), farinha de carcaça de jundiás com vísceras (FCJCV), farinha de carcaça de jundiá sem vísceras (FCJSV) e farinha de jundiás inteiros (FJI). No experimento II (EXP II), níveis de inclusão de FCJCV foram testados (0; 3,75; 7,5; 15 e 30%). No plasma, foram quantificadas proteínas totais circulantes, colesterol total, triglicerídeos, glicose, albumina e aminoácidos. No fígado, analisou-se glicose, amônia, proteínas totais, glicogênio, aminoácidos e transaminases. No estômago, foi determinada a atividade de protease ácida e, no intestino, tripsina e quimotripsina. No EXP I, foram observados menores níveis de glicose no plasma e alanina aminotransferase (ALT) no fígado, para o tratamento FCJSV, e maiores índices destes para FCO. A atividade da protease ácida e da quimotripsina foram menores para a FCO e maior para a FCJCV. No EXP II, os índices de aminoácidos livres e colesterol total no plasma aumentaram com a elevação dos níveis de inclusão da FCJCV na dieta. A incorporação de farinhas de resíduos de jundiá à dieta altera a bioquímica plasmática, os parâmetros hepáticos e digestivos dos juvenis de jundiá, porém essas alterações não influenciaram na saúde dos peixes, demonstrando sua qualidade nutricional e eficiência no uso em dietas para peixes.

The objective of this study was to analyze the influence of the addition of jundiá (Rhamdia quelen) waste meal in the diet of this species, on plasmatic biochemistry, liver and digestive parameters. Experiment I (EXP I) compared diets with 30% of meat and swine bones (FCO), Jundiá carcass meal with viscera (FCJCV), Jundiá carcass meal without viscera (FCJSV) and full Jundiá meal (FJI). In experiment II (EXP II), different FCJCV levels were tested (0, 3.75, 7.5, 15, and 30%). Total circulating proteins, cholesterol, triglyceride, glucose, albumin and amino acids were quantified in plasma. Glucose, ammonia, total protein, glycogen, amino acids and transaminases were analyzed in the liver. The acid protease activity was determined in the stomach, and trypsin and chymotrypsin activity were established in the intestine. EXP I, found a lower glucose concentration in plasma and alanine aminotransferase (ALT) in the liver for FCJSV treatment and higher levels of these parameters for FCO treatment. The activity of acid protease and chymotrypsin were lower for FCO and higher for FCJCV. In EXP II, rates of free amino acids and total cholesterol in plasma increased with increasing levels FCJCV dietary. The incorporation of Jundiá waste meal diet modified plasmatic biochemistry, liver and digestive parameters of Jundiá juveniles, but these changes did not influence the fish health, demonstrating its nutritional quality and efficiency in fish diet.

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This study evaluated parameters of oxidative stress and antioxidant profile in fish after herbicide exposure. Cyprinus carpio were exposed to quinclorac (initial concentration 344.60µg/L) for 7, 30, and 90 days under rice field condition. Thiobarbituric acid-reactive substances (TBARS) were evaluated in brain, liver and muscle tissues, and protein carbonyl in liver. Enzymatic parameters such as catalase (CAT) and gluthatione S-transferase (GST) activities also were studied in liver. TBARS levels fluctuated in the brain showing increase in 7 days and decrease in 30 days, while in liver it was observed increase in 7 and 30 days, as well as in muscle after 30 and 90 days. The protein carbonyl was also increased after 30 and 90 days of herbicide exposure. CAT and GST activities were decreased after 30 and 90 days, respectively. The alterations observed suggest that a commercial formulation containing quinclorac causes oxidative damage in different tissues of carp after a long time of exposure. This study pointed out the importance of quinclorac toxicity considering the concentration used in rice fields.

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In this study, we investigated zinc and copper effects on acetylcholinesterase (AChE, EC. 3.1.1.7) activity and metal accumulation in tissues of native fish Leporinus obtusidens (piava). Fish were exposed to 10 and 20 % of the LC(50) that corresponded at 2.28 and 4.57 mg/L (zinc) and 0.018 and 0.038 mg/L (copper) for 30 and 45 days. The AChE activity was evaluated in brain and white muscle of fish and metals accumulation was measured in kidney, liver, muscle and brain. Exposure to zinc and copper significantly increased AChE activity in both tissues and times tested, except for brain AChE activity at 2.28 mg/L of Zn (II) after 45 days where a reduction of 52.5 % was observed. Fish exposed to zinc showed accumulation of this metal in liver and kidney in both concentrations and times tested. A different result was obtained for copper: significant copper accumulation was obtained only in brain at both concentrations tested after 45 days of exposure. These results suggest that piavas exposed to zinc and copper showed changes in AChE activity and also demonstrate accumulation in some tissues. These results demonstrate that L. obtusidens could be a good bioindicator to evaluate water containing metals. The metal accumulation absence in muscle tissue is an indicative of low potential contamination by metals in this fish species.

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Field and laboratory experiments were performed to evaluate toxicological responses of Cyprinus carpio exposed to the commercial herbicide clomazone (500 mg l(-1)). Fish were exposed to 0.5 mg l(-1) of the formulated herbicide for 7, 30, and 90 days. Fish were exposed to clomazone in field conditions (7, 30, or 90 days trapped in submersed cages together with rice crops) and in laboratory conditions where the fish were placed in 45-l tanks with tap water only for 7 days. Fish exposed for 7, 30, or 90 days showed no alterations in acetylcholinesterase (AChE) activity under field conditions. Under laboratory conditions, decreased muscle AChE activity was observed only after 7 days of exposure. During the same evaluation period (7 days), oxidative stress parameters changed under both field and laboratory conditions; however, metabolic parameters were altered only under field conditions. Disorders in oxidative stress parameters and metabolism were evident in different tissues up to day 90 after treatment. These overall results show that AChE activity changed only under laboratory conditions. Oxidative stress, along with metabolic parameters, may be good indicators of herbicide contamination in C. carpio under rice-field conditions.

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The effects of commercial glyphosate herbicide formulation on the activity of acetylcholinesterase (AChE) enzyme and oxidative stress were studied in Cyprinus carpio exposed for 96 h to 0.0, 0.5, 2.5, 5.0 and 10.0 mg/L and then allowed to equal recovery period in water without herbicide. The activity of AChE was inhibited in the brain and in the muscle after exposure. However, after recovery period brain and muscle AChE activity increased. Brain thiobarbituric acid reactive species (TBARS) were measured as an indicator of oxidative stress. Increased TBARS levels were observed with all concentrations tested of the glyphosate formulation, and remained increased after the recovery period. The results recorded clearly indicate lipid peroxidation and anti-AChE action induced by Roundup(®) exposure.

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In recent years, commercial glyphosate herbicide formulations have been widely used in agriculture to control aquatic weeds. These pesticides may result in disruption of ecological balance, causing damage to nontarget organisms including fish. Teleostean fish (Leporinus obtusidens) were exposed to commercial glyphosate herbicide formulation at 0 (control), 3, 6, 10 or 20 mg L(-1) for 96 h. The effects of herbicide on plasmatic metabolic parameters, thiobarbituric acid reactive substances (TBARS), catalase activity, protein carbonyl, and mucus layer parameters were studied. Plasmatic glucose and lactate levels increased but protein levels showed reduction after herbicide exposure. TBARS levels in brain showed a reduction at all tested concentrations. However, liver demonstrated increased TBARS levels at all tested concentrations, whereas in white muscle TBARS production did not change after exposure to herbicide. Fish exposed to all concentrations of glyphosate showed increase in liver catalase activity and protein carbonyl. Herbicide exposure increased protein and carbohydrate levels of the mucus layer at all tested concentrations. The present results showed that, in 96 h, glyphosate changed toxicological parameters analyzed in piava. Parameters measured in this study may be useful in environmental biomonitoring.

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The effects of commercial formulation containing quinclorac and metsulfuron-methyl herbicides on acetylcholinesterase (AChE), antioxidant profile and metabolic parameters in teleost fish (Leporinus obtusidens) were studied. The fish were exposed during 90 days to commercial formulation containing quinclorac (204 µg L(-1)) and metsulfuron-methyl (5.8 µg L(-1)) herbicides in rice field irrigated condition. AChE activity in the brain and muscle decreased after exposure to both commercial formulations. The same response was observed for the TBARS levels in brain, liver and muscle. Liver catalase activity reduced after exposure to commercial formulation containing quinclorac and metsulfuron-methyl herbicides. Metabolic parameters in the liver and white muscle (glycogen, lactate, protein and glucose) were determined. These parameters showed different changes after exposure to both commercial formulations. This study pointed out long-term effects of exposure to commercial formulations containing herbicides used in rice on metabolic and enzymatic parameters in tissues of L. obtusidens.

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Cyprinus carpio was exposed to imazethapyr and imazapic at laboratory and at field conditions. The laboratory experiment was carried out for 7 days and at rice field for 7, 30 and 90 days. Oxidative stress parameters and antioxidant profile were studied as well as metabolic parameters. After 7 days, brain AChE activity increases in laboratory and field, but in muscle, reduction was observed only in laboratory. At the same period, brain and muscle TBARS and liver CAT increase in the laboratory. Metabolic parameters showed changes in both conditions and exposure periods. After 30 days in rice field, brain AChE activity decreases and in muscle it was enhanced. After 90 days in field, only muscle AChE activity was reduced. The disorders in oxidative stress parameters and metabolism remained, indicating mainly a protein catabolism. This study pointed out short- and long-term effects of rice herbicides at environmentally relevant concentrations on toxicological parameters in tissues of C. carpio.

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Antioxidant enzymes and oxidative stress indicators were evaluated in fish exposed to different concentrations of the herbicide Roundup 48% (Monsanto, St. Louis, MO): control (none), 0.45, or 0.95 mg/l. After exposure for 8 days to herbicide, fish were transferred to clean water for a recovery response period (also 8 days). Herbicide increased thiobarbituric acid reactive species in liver and muscle at the higher concentration and in the brain at both concentrations. Protein carbonyl in liver increased after exposure. Catalase (CAT) and superoxide dismutase (SOD) activities and ascorbic acid levels in liver did not change in fish exposed to both concentrations. Glutathione S-transferase (GST) levels decreased at both concentrations. The nonprotein thiol levels decreased at the 0.95 mg/l concentration. During the recovery period, some of the parameters that had altered, such as protein carbonyl content, later recovered. However, some enzymes reacted during this period, e.g., GST increased its activity, possibly indicating a compensatory response against the toxic conditions. In contrast, CAT and SOD activities decreased during the recovery period, indicating herbicide toxicity. Oxidative stress that occurred during the exposure period was likely due to the increased lipid peroxidation and protein carbonyl content. The results concerning oxidative and antioxidant profiles indicate that short-term exposure to herbicide is capable of causing oxidative stress in fish tissues.

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The effects of sublethal cadmium concentrations on oxidative stress parameters were evaluated in Rhamdia quelen. The fish were exposed to 0.44, 236, and 414 µg l⁻¹ cadmium for 7 and 14 days, followed by the same time periods for recovery. Enzymes, such as catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST), and indicators of oxidative stress, such as thiobarbituric acid-reactive species (TBARS) and protein carbonyl, were verified in fish tissues. In addition, the accumulation of cadmium was evaluated in these tissues. Our results indicate that CAT and GST levels decreased in gills after exposure periods associated with increased TBARS levels. In hepatic tissue, CAT, GST, TBARS, and protein carbonyl levels increased after 7 days of exposure, whereas SOD activity decreased after exposure for 14 days. In the kidney, TBARS levels decreased after exposure for 7 days and increased after exposure for 14 days. During the recovery periods, some variations persisted in gills, liver, and kidney. Cadmium accumulation was most significant in liver, followed by kidney and gills. These results indicate that cadmium concentrations studied invoke a stress response in silver catfish.

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