Neotropical Fish Prochilodus Lineatus Research Articles

Impact of antiparasitic used in livestock: effects of ivermectin spiked sediment in Prochilodus lineatus, an inland fishery species of South America.

Ivermectin (IVM) is a widely used antiparasitic. Concerns have been raised about its environmental effects in the wetlands of Río de la Plata basin where cattle have been treated with IVM for years. This study investigated the sublethal effects of environmentally relevant IVM concentrations in sediments on the Neotropical fish Prochilodus lineatus. Juvenile P. lineatus were exposed to IVM-spiked sediments (2 and 20µg/Kg) for 14days, alongside a control sediment treatment without IVM. Biochemical and oxidative stress responses were assessed in brain, gills, and liver tissues, including lipid damage, glutathione levels, enzyme activities, and antioxidant competence. Muscle and brain acetylcholinesterase activity (AChE) and stable isotopes of 13C and 15N in muscle were also measured. The lowest IVM treatment resulted in an increase in brain lipid peroxidation, as measured by thiobarbituric acid reactive substances (TBARs), decreased levels of reduced glutathione (GSH) in gills and liver, increased catalase activity (CAT) in the liver, and decreased antioxidant capacity against peroxyl radicals (ACAP) in gills and liver. The highest IVM treatment significantly reduced GSH in the liver. Muscle (AChE) was decreased in both treatments. Multivariate analysis showed significant overall effects in the liver tissue, followed by gills and brain. These findings demonstrate the sublethal effects of IVM in P. lineatus, emphasizing the importance of considering sediment contamination and trophic habits in realistic exposure scenarios.

Cadmium effects on the freshwater teleost Prochilodus lineatus: Accumulation and biochemical, genotoxic, and behavioural biomarkers

In order to evaluate the effects of Cd, juveniles of the Neotropical fish Prochilodus lineatus were exposed to 1 and 10 μg L-1 Cd, for 24 and 96 h. Fish exposed to Cd showed metal accumulation in the gills, kidney, and liver, an increase in DNA damage in erythrocytes, and an increase in lipid peroxidation (LPO) in the kidney. Cd exposure also caused a reduction in catalase activity, metallothionein induction, and LPO in the liver. Cd stimulated the swimming activity of exposed fish, resulting in longer swimming times and distances travelled, especially for the shortest exposure time. Changes in acetylcholinesterase activity (AChE) in the muscle and brain are probably related to these behavioural responses. These results show that Cd affects the functioning of several organs in P. lineatus, which is indicated by the genotoxic damage and changes in the AChE and swimming pattern of the exposed fish.

Sublethal Effects of Biogenic Silver Nanoparticles and Silver Nitrate in the Neotropical Fish Prochilodus lineatus: Is the Nanoform Really Less Toxic?

Sublethal Effects of Biogenic Silver Nanoparticles and Silver Nitrate in the Neotropical Fish Prochilodus lineatus: Is the Nanoform Really Less Toxic?

Effects of melatonin supplementation on the quality of cryopreserved sperm in the neotropical fish Prochilodus lineatus

The cryopreservation process causes damage to sperm structures and supplementation of the cryoprotective medium is an alternative to reduce these damages. The aim of this study was to determine the effect of melatonin supplementation on post-thaw sperm quality in Prochilodus lineatus. The cryoprotective medium was supplemented with 2.00, 2.75, 3.50, and 4.25 mM melatonin, and the control group (without melatonin). Sperm motility parameters, membrane integrity, sperm morphology, oxidative stress (lipid peroxidation and enzymatic activity), and fertilization capacity were analyzed in the post-thaw sperm. Samples cryopreserved with 2.00 mM melatonin yielded higher sperm motility rate than other treatments with the addition of melatonin. Sperm curvilinear velocity (VCL) and average path velocity (VAP) were higher in samples containing 2.00 mM melatonin than in other treatments. Samples from control and with 2.00 mM melatonin presented higher membrane integrity and morphological normality than samples containing 4.25 and 2.75 mM melatonin, respectively. Regarding oxidative stress, lower lipid peroxidation (LPO) occurred in 2.75 and 3.50 mM melatonin, compared to control. While higher enzyme activity of catalase (CAT) occurred in the control than in other treatments, no differences were observed in the activity of superoxide dismutase (SOD). Higher fertilization and hatching rates occurred at 2.75 mM melatonin compared to 4.25 mM. Although no significant differences were observed in LPO between the control and samples supplemented with 2 mM melatonin, it was observed that this dosage of melatonin allowed higher VCL and VSL and reduced values of CAT. However, as there are no differences in motility and fertilization rates between the control and the 2 mM concentration, it is suggested that further studies be carried out with lower concentrations of melatonin in order to determine its effectiveness as an antioxidant in the sperm of this species.

Whole-body bioconcentration and biochemical and morphological responses of gills of the neotropical fish Prochilodus lineatus exposed to 2,4-dichlorophenoxyacetic acid or fipronil individually or in a mixture.

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and the insecticide fipronil have been used widely in agriculture and detected in aquatic ecosystems, where they threaten wildlife. This study evaluated the whole-body bioconcentration and the biochemical and morphological changes in the gills of the neotropical fish Prochilodus lineatus exposed for 96h to 2,4-D or fipronil as single compounds or as a mixture (2,4-D+fipronil). Fish exposed to either compound alone bioconcentrated 2,4-D (77±23ng g-1 fish dry mass) and fipronil (789±178ng g-1 fish dry mass). Fish exposed to 2,4-D+fipronil bioconcentrated fipronil (683±73ng g-1 fish dry mass) but not 2,4-D. In the gills, catalase (CAT) and glutathione-S-transferase (GST) activities and the lipid peroxidation (LPO) level increased after exposure to 2,4-D. GST activity increased after exposure to fipronil. Conversely, no changes occurred in CAT and GST activities and LPO upon exposure to 2,4-D+fipronil. Histopathological changes such as hyperplasia, cellular hypertrophy, epithelial lifting, and vascular congestion were frequent in the gills of fish exposed to 2,4-D or fipronil individually or 2,4-D+fipronil. The mitochondria-rich cell (MRC) density increased on gill surface in fish exposed to fipronil or 2,4-D+fipronil. Only exposure to 2,4-D alone induced oxidative stress in the gills. Most morphological changes showed defense responses against the pesticides; however, hypertrophy and the change in MRC indicated compensatory responses to maintain the gill osmoregulatory function. The 2,4-D+fipronil mixture showed antagonistic interaction, except for the MRC fractional area at gill surface, which showed synergistic interaction. This is the first report showing antagonistic interaction of 2,4-D and fipronil in the gills after exposing fish to the mixture of both pesticides. The biochemical and morphological changes in gills endanger the gill functions, a phenomenon that implies an energy cost for fish.

Acute Exposure to Biogenic Nanosilver Produced from Fusarium oxysporum in a Neotropical Fish.

Biogenic nanosilver (bNAg) has emerged as a potentially less toxic alternative to synthetic nanosilver. However, no studies have evaluated its effects on a fish species from the Neotropical region. Thus, our aim was to evaluate the effects of a bNAg on the Neotropical fish Prochilodus lineatus. For this purpose, after 24h of exposure to 100µg L-1 of bNAg, blood samples were collected to evaluate hematological, genotoxic, and plasma parameters. Gills and liver were sampled to evaluate biomarkers of oxidative stress and brain samples were used to assess neurotoxicity. The fish presented hyperglycemia, an increased number of erythrocytes, a reduction in antioxidant enzyme activity in both tissues evaluated, and a decrease in lipid peroxidation in the gills. We concluded that P. lineatus is a sensitive species to this nanoparticle, since it presented alterations in several biomarkers after an acute exposure.

Ivermectin: A multilevel approach to evaluate effects in Prochilodus lineatus (Valenciennes, 1836) (Characiformes, Prochilodontidae), an inland fishery species

Ivermectin (IVM) is one of the most widely used antiparasitics worldwide. It is a potent and effective drug for treatment and prevention of internal and external parasitic infections of livestock and humans. IVM is excreted unchanged in manure of treated animals. Thus, residues of IVM may reach aquatic systems, affecting non-target organisms such as fish. Although the presence of IVM in aquatic environments has been reported, a multilevel approach (from cellular to behavioral responses) is necessary to determine the health of exposed organisms and the environmental risks associated. The aim of the present study was to investigate the response of the Neotropical fish Prochilodus lineatus, one of the main target species of South American freshwater fisheries, exposed to environmental concentrations of IVM: low (0.5 μg L−1) and high (1.5 μg L−1). Behavioral responses were assessed in juvenile fish and included water column use, routine swimming, total distance travelled, total activity time and Maximum swimming speed achieved during the escape response. Biochemical/oxidative stress responses assessed included brain acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) activities; total antioxidant competence against peroxyl radicals (ACAP) and lipid oxidative damage (TBARs). Hematological biomarker responses included blood glucose levels, hematocrit, hemoglobin concentration, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscular volume. Condition factor and hepatosomatic index were also calculated. The lowest IVM concentration caused a significant decrease in GST activity and maximum swimming speed during the escape response. Multivariate analysis with biochemical/stress and behavioral data revealed overall effects of IVM treatments. This multilevel analysis shows detrimental effects related to swimming behavior and predator avoidance which could affect population size and size-structure of P. lineatus. To our knowledge this is the first attempt to assess the effects of IVM on Neotropical fishes using an integrative approach based on biomarkers from different levels of biological organization.

An integrated approach in subtropical agro-ecosystems: Active biomonitoring, environmental contaminants, bioaccumulation, and multiple biomarkers in fish

Aquatic contamination in agricultural areas is a global problem, characterized by a complex mixture of organic and inorganic pollutants whose effects on biota are unpredictable and poorly investigated. In this context, in the present study, the Neotropical fish Prochilodus lineatus was confined in situ for 120 days in two sites with different levels of anthropic impact: 1) a fish hatchery station, within the State University of Londrina (reference site - REF) and 2) an agro-ecosystem area in one of the most productive regions of southern Brazil (experimental site - EXP). We evaluated multiple biomarkers at different levels of biological organization, such as biotransformation and antioxidant enzymes, oxidative damages, DNA damages and liver histopathology. We also evaluated the occurrence of 22 organochlorine pesticides (OCPs) and 6 trace metals in water and sediment; and 33 current-use pesticides (CUPs) in the water; besides the presence of OCPs in the liver and metals in different tissues of the confined fish. The chemical analysis confirmed that the two environments presented different levels of contamination. We verified a distribution gradient of data in the principal component analysis (PCA), separating the REF fish to one side and the fish at the agricultural area (EXP) to the other side. In general, the biomarker responses were more altered in fish from the EXP than fish from the hatchery station; and this fish presented a greater accumulation of endosulfan (an increase of 18× compared to basal value) and showed oxidative, genetic, and histological damage. Through the Biomarkers Response Index (BRI), we found that the EXP fish demonstrated a decrease in health status compared with the REF fish during the confinement time, due to their exposure to a higher concentration of contaminants. In conclusion, the use of multiple biomarkers at different response levels is an important tool for environmental monitoring.

Mitochondria-rich cells adjustments and ionic balance in the Neotropical fish Prochilodus lineatus exposed to titanium dioxide nanoparticles

Manufactured titanium dioxide nanoparticles (TiO2-NP) have been intensely applied in numerous industrial products and may be a risk for aquatic systems as they are not completely removed from domestic and industrial wastes after water treatment. This study evaluated the osmo- and ionic balance, Na+/K+-ATPase, H+-ATPase and carbonic anhydrase activities and the mitochondria-rich cells (MRC) in the gills and kidney of the Neotropical fish Prochilodus lineatus after 2 (acute) and 14 (subchronic) days of exposure to nominal 0, 1, 5, 10 and 50 mg L−1 TiO2-NP. The nominal concentrations corresponded to 0.0, 0.6, 1.6, 2.7 and 18.1 mg L-1 suspended TiO2-NP, respectively, in the water column one hour after NP introduction and were maintained for at least 24 h. Acute exposure to TiO2-NP decreased plasma osmolality and Ca2+ levels. Na+/K+-ATPase, H+-ATPase and carbonic anhydrase activities were inhibited in the gills, but not in the kidney. Total MRC density did not change in gills and kidneys. At gill surface, total MRC density decreased in fish exposed to 50 mg L−1 TiO2-NP and the total MRC fractional surface area unchanged although, there were some changes in the fractional area of MRC with apical microvilli (MRCm) and MRC with apical sponge-like structure (MRCs). MRCm was more abundant than MRCs. After subchronic exposure, there was no change in plasma osmolality, ionic balance and enzyme activities. Total gill MRC density increased in the filament epithelium and renal tubules. In the gills, MRC contacting water exhibited some adjustments. Total MRC and fractional surface area unchanged, but there was an increase of MRCs contacting water at gill surface after exposure to10 and 50 mg L−1 TiO2-NP. MRC proliferation in filament epithelium and in renal tubules as well as the increasing MRCs at gill surface may have contributed to avoid change in plasma osmolality, ionic balance and enzyme activities and suggested a cellular physiological and morphological response to restore and maintain osmotic and ionic homeostasis after subchronic exposure.

Chromium accumulation and biomarker responses in the Neotropical fish Prochilodus lineatus caged in a river under the influence of tannery activities

In order to assess the effects of tannery effluents (TE) in organism health, juveniles of Prochilodus lineatus were submitted to in situ tests at four different river locations: site A – upstream of the tannery; site B – next to the tannery; and sites C and D – downstream of the tannery. After 96 h exposure in the river, samples of fish tissue, river water and sediment were collected in order to quantify chromium (Cr) concentrations. Tissue samples were used to assess the activity of ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), the content of glutathione (GSH) and metallothionein (MT) and the occurrence of lipid peroxidation (LPO) and DNA damage. Higher Cr concentrations were detected in the water and sediments from site B and in the liver of fish confined at site B, compared to the other sites. Fish caged at site B demonstrated higher levels of liver MT and hepatic EROD activity in relation to fish caged at the other sites. Moreover, fish from site B presented increased liver and branchial GST activities, as well as more GSH in the liver, than fish from site A. There were no significant variations in the occurrence of LPO and DNA damage among fish caged at the different sites. Thus, TE increased Cr levels in the water, sediments, and fish livers and stimulated the synthesis of MT and GSH and the activities of EROD and GST. In conclusion, TE affect the quality of the river and promote changes in biochemical biomarkers and Cr accumulation in P. lineatus.

Nanosilver toxicity in gills of a neotropical fish: Metal accumulation, oxidative stress, histopathology and other physiological effects

The widespread and increasing use of silver nanoparticles (AgNP) as biocide results in an unknown release into the aquatic environment. In order to contribute to the understanding of their potential toxicity, the aim of this study was to analyze branchial multiple biomarkers on the neotropical fish Prochilodus lineatus. We exposed fish to sublethal AgNP concentrations: 0 (control), 2.5 and 25.0µgL−1. After 5 and 15 days, we analyzed in gills total Ag accumulation, oxidative stress markers (antioxidant enzymes, lipid peroxidation and antioxidant capacity against peroxyl radicals), aspartate and alanine aminotransferases activities (ALT, AST) and histopathologies (morphometric analysis, proportion of the secondary lamellae available for gas exchange, reaction indexes, and organ index -Igills-) that included mucus cell count (MCc). The Ag accumulation after 15 days was five times higher than after 5 days in the case of 25.0μg AgNP L−1-exposure. Regarding oxidative stress, all enzymes activities were inhibited after 5 days at both AgNP concentrations. ALT activity decreased and a reduction in the antioxidant capacity was evidenced after 2.5µg AgNP L−1 and 15 days. LPO levels and AST activity increased after the highest time of exposure and AgNP concentration, and the same occurred with Igills. MCc increased after 15 days at both AgNP concentrations. The results confirmed that the presence of low AgNP concentrations, in short and subchronic exposures, generates alterations in stress biomarkers and in the structure of this vital organ that are the gills.

DNA damage and oxidative stress induced by imidacloprid exposure in different tissues of the Neotropical fish Prochilodus lineatus

Imidacloprid (IMI), a systemic neonicotinoid insecticide widely used in worldwide scale, is reported in freshwater bodies. Nevertheless, there is a lack of information about IMI sublethal effects on freshwater fish. Thus, the aim of this study was to identify the potential hazard of this insecticide to the South American fish Prochilodus lineatus exposed for 120 h to four IMI concentrations (1.25, 12.5, 125, and 1250 μg L−1). A set of biochemical, genotoxic and physiological biomarkers were evaluated in different organs of the fish. IMI exposure induced significant changes in the enzymatic profiles of P. lineatus, with alterations in the activity of biotransformation and antioxidant enzymes in different tissues. Redox balance of the tissues was affected, since oxidative damage such as lipoperoxidation (LPO) and protein carbonylation (PCC) were evidenced in the liver, gills, kidney and brain of fish exposed to different IMI concentrations. Fish exposed to all IMI concentrations showed decreased blood glucose indicating an increase of energetic demand. DNA damage was evidenced by the comet test, in the erythrocytes of fish all the concentrations evaluated. We integrated these results in the Integrated Biomarker Response (IBR) index, which evidenced that the organs most affected by IMI exposure were the liver and kidney, followed by the gills. Our results highlight the importance of investigating different target tissues after IMI exposure and show the sublethal effects of IMI in some of them; they also warn to the possible consequences that fish living in freshwater ecosystems can suffer due to IMI exposure.

Effect of anesthetic, tag size, and surgeon experience on postsurgical recovering after implantation of electronic tags in a neotropical fish: Prochilodus lineatus (Valenciennes, 1837) (Characiformes: Prochilodontidae)

ABSTRACT Implantation of telemetry transmitters in fish can be affected by different parameters. This study aimed to evaluate the effect of type of anesthetic, tag size, and surgeon experience on surgical and postsurgical wound healing in the neotropical fish Prochilodus lineatus . In total, eighty fish were surgically implanted with telemetry transmitters and forty fish were kept as controls. Forty fish were implanted with a small tag and other forty were implanted with a large tag. Similarly, forty fish were anesthetized with eugenol and forty fish were anesthetized by electroanesthesia, and forty surgeries were performed by an expert surgeon and forty surgeries were performed by novice surgeons. At the end of the experimental period seventeen (21.3%) tagged fish had postsurgical complications, including death (1.3%), tag expulsion (2.5%), antenna migration (2.5%), and infection (15%). Tag size was the key determinant for postsurgical complications. Surgical details and postsurgical wound healing were not affected by type of anesthetic. Incision size, duration of surgery, and wound area were significantly affected by tag size and surgeon experience, and the number of sutures was significantly affected by tag size only. The results indicate that successful implantation of telemetry transmitters is dependent upon surgeon experience and tag size.

Multiple biomarker responses in Prochilodus lineatus subjected to short-term in situ exposure to streams from agricultural areas in Southern Brazil

In order to assess the quality of streams susceptible to contamination by pesticides we apply biochemical and genotoxic biomarkers in the Neotropical fish Prochilodus lineatus submitted to in situ tests. Fish were caged, for 96h, in two streams located in areas with intensive use of pesticides, the Apertados (AP) and the Jacutinga (JC), and in a small stream (Godoy stream — GD) found inside a forest fragment adjacent to a State Park. Biochemical parameters, such as biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST), non-protein thiols (NPSH), lipoperoxidation (LPO), protein carbonylation (PCO) and acetylcholinesterase (AChE) were evaluated in various fish organs, as well as genotoxic biomarkers (damage to DNA and occurrence of micronuclei and erythrocyte nuclear abnormalities). Samples of water and sediment were collected for analysis of metals (Cu, Cr, Pb, Ni, Mn, Cd and Zn), organochloride pesticides, and triazine and glyphosate herbicides. We observed an increase in liver GST activity in fish at AP and gill GST activity in fish at JC. An increase in liver LPO was also observed in fish exposed to AP and JC. The same animals also exhibited increased DNA damage and erythrocyte nuclear abnormalities (ENAs) compared to the fish kept in GD. A number of compounds showed concentrations higher than the permitted levels, in particular, dichlorodiphenyltrichloroethane (DDT), its metabolites dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), hexachlorocyclohexanes (HCH), heptachloride, diclofluanid and aldrins. These pesticides were detected at higher concentrations in water and sediment samples from AP, followed by JC and GD. The Integrated Biomarker Response Index (IBR) indicated that AP and JC (AP: 21.7>JC: 18.5>GD: 12.6) have the worst environmental quality. Integrated biomarker analysis revealed that the alterations observed related well with the levels of environmental contaminants, demonstrating the effectiveness of this biomonitoring approach.

Bioaccumulation of nickel and its biochemical and genotoxic effects on juveniles of the neotropical fish Prochilodus lineatus

Juveniles of the freshwater fish Prochilodus lineatus were exposed to three concentrations of nickel (Ni): 25, 250 and 2500µgL-1 or water only for periods of 24 and 96h to test for Ni bioaccumulation, its effects on antioxidant defenses and metallothioneins, and the occurrence of DNA damage. After exposure, the fish were sampled and tissue removed from the gills, liver, kidney and muscle to test for Ni accumulation and conduct biochemical (gills and liver) and genotoxic (blood cells and gills) analyses. The results showed that Ni accumulates in the organs in different proportions (kidney>liver>gills>muscle) and accumulation varied according to exposure time. Metallothionein (MT) levels increased in the liver and gills after exposure to Ni, implying that the presence of Ni in these tissues could induce MT synthesis. We also observed that Ni exposure affected antioxidant defenses, increasing lipid peroxidation in the liver of fish exposed to Ni for 96h at the highest concentration tested. DNA damage increased in both blood cells and gills of fish exposed to all Ni concentrations, indicating the genotoxic potential of Ni on fish. We therefore concluded that Ni accumulates in various tissues and results in oxidative and DNA damage in P. lineatus, and that the maximum permitted Ni concentration set in Brazilian legislation (25µgL−1) for freshwaters is not safe for this species.

Acute effects of cadmium on osmoregulation of the freshwater teleost Prochilodus lineatus: Enzymes activity and plasma ions

Cadmium (Cd) is a trace element that is very toxic to fish. It is commonly found in surface waters contaminated with industrial effluents. When dissolved in water, Cd can rapidly cause physiological changes in the gills and kidneys of freshwater fish. The objective of this study was to evaluate the acute effects of Cd on the osmoregulation of the Neotropical fish Prochilodus lineatus. Juvenile fish were exposed to Cd at two concentrations [1 (Cd1) and 10 (Cd10) μgL−1] for 24 and 96h. The effects of Cd were evaluated through the analysis of ions (Na+, K+, Ca2+, and Cl−) and plasma osmolality, and by measuring the activities of enzymes involved in osmoregulation obtained from the gills and kidney. Fish exposed to Cd for 24 and 96h showed a decrease in Na+/K+-ATPase activity in the gills and kidney. The activity of carbonic anhydrase decreased in the gills after 24h and in both tissues after 96h of Cd exposure. The gill Ca2+-ATPase activity also decreased with Cd exposure, with a concomitant drop in the plasma concentration of Ca2+. Despite the hypocalcemia, there were no changes in the concentration of the ions Na+, K+, and Cl− or in plasma osmolality. Among the enzymes involved in ion transport, H+-ATPase was the only enzyme that showed increased activity in gills, whereas its activity in kidney remained unchanged. The results of this study demonstrate that waterborne Cd at the maximum concentrations set by Brazilian guidelines for freshwater affects the gills and kidney functions of P. lineatus. Acute exposure to Cd resulted in the decrease of the activity of enzymes, which culminated with the loss of the fish's ability to regulate the levels of calcium in the blood, leading to hypocalcemia.

Effects of the surfactant polyoxyethylene amine (POEA) on genotoxic, biochemical and physiological parameters of the freshwater teleost Prochilodus lineatus

The surfactant polyoxyethylene amine (POEA) is added to several formulations of glyphosate herbicides that are widely used in agriculture and can contaminate aquatic ecosystems. In the present study, an integrated approach examining genotoxic, biochemical and physiological parameters was employed to evaluate acute effects of POEA on the Neotropical fish Prochilodus lineatus. Juvenile fish were exposed to 0.15mg·L−1 (POEA 1), 0.75mg·L−1 (POEA 2) and 1.5mg·L−1 (POEA 3) of POEA or only water (CTR), and after 24h exposure samples of blood and liver were taken. Compared with CTR, liver of fish exposed to POEA 2 and POEA 3 showed increased activity of 7 ethoxyresorufin-O-deethylase and increased content of glutathione, whereas the activity of glutathione-S-transferase was diminished. On the other hand, fish of the group POEA 1 showed an increase in the activity of superoxide dismutase and in the occurrence of lipid peroxidation. Fish exposed to POEA 3 presented increased hepatic activity of glutathione peroxidase and reduced plasma cortisol. The exposure to POEA at all concentrations tested caused an increase in plasma lactate and a decrease in the hepatic activity of catalase, in the number of red blood cells and in hemoglobin content. The comet assay used for analyzing DNA damage in blood cells indicated the genotoxicity of the surfactant at all concentrations tested. Taken together these results show that POEA can cause effects at various levels, such as hemolysis, DNA damage and lipid peroxidation, which are directly related to an imbalance in the redox state of the fish.

Biochemical and genetic alterations in the freshwater neotropical fish Prochilodus lineatus after acute exposure to Microcystis aeruginosa

Microcystins are secondary metabolites produced by different species of cyanobacteria, such as Microcystis aeruginosa (MA). In this study, the biochemical and genetic effects of lyophilized MA were evaluated in the neotropical fish Prochilodus lineatus exposed to 1 or 2 mg L-1 lyophilized MA (treated group) or only water (control group) in static toxicity tests for 24 and 96 h. The gills and liver were used in the analysis of biotransformation enzymes and antioxidant defenses, blood and gill cells in genetic analysis and in brain and muscle it was determined the activity of acetylcholinesterase (AChE). The results showed the biotransformation pathway activation due to the increase in hepatic CYP1A and in branchial and hepatic glutathione S-transferase (GST). The antioxidant defense proved to be greatly affected by MA exposure leading to changes, both in gills and liver, in the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and in the content of tripeptide glutathione (GSH). Lipid peroxidation was not detected, but damage to DNA molecule was observed in blood cells. In conclusion, it can be state the lyophilized MA is able to promote changes in the biochemical and genetic parameters of P. lineatus.

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 48h) exposed to 2 or 10μgL−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 Roundup Transorb on fish: Hematology, antioxidant defenses and acetylcholinesterase activity

Roundup Transorb® (RDT) is a glyphosate-based herbicide containing a mixture of surfactants. The objective of this work was to evaluate the effects of this herbicide on the Neotropical fish Prochilodus lineatus. Juvenile fish were acutely exposed (6, 24 and 96 h) to 1 mg L −1 of RDT (RDT 1), 5 mg L −1 of RDT (RDT 5) or only water (control) and blood samples for hematological analysis, liver for antioxidants analysis, and brain and muscle for acetylcholinesterase (AChE) determination, were collected. RDT effects were more evident in fish exposed to the higher concentration of the herbicide. Hematologic alterations appeared only after 96 h exposure, when fish showed an increase in the hematocrit and in the number of both red and white blood cells. After 6 h exposure fish showed a transient reduction in superoxide dismutase and catalase activity. RDT also inhibited glutathione-S-transferase, after 6 and 24 h of exposure. The reduction in these enzymes is probably related to the occurrence of lipid peroxidation (LPO) in fish exposed to the herbicide for 6 h. LPO returned to control levels after 24 and 96 h exposure to RDT, when fish showed an increased activity of glutathione peroxidase. The content of reduced glutathione also increased after 96 h exposure. Thus, after 24 and 96 h the antioxidant defenses were apparently enough to combat ROS, preventing the occurrence of oxidative damage. The exposure to RDT for 96 h led to an inhibition of AChE in brain and muscle at rates which may not be considered a life-threatening situation.