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Microplastics (MPs) and glyphosate-based herbicides (GBH) are among the most common contaminants in aquatic environments. In Brazilian rivers, both contaminants were found in elevated levels, leading to a high probability of their association, which can alter their individual effects and potentially intensify their toxicity. This study evaluated the isolated and combined effects of polyethylene microplastics (PE-MPs) and GBH on Oreochromis niloticus using multi-biomarkers of toxicity. The fish were subjected to a 96-h exposure period, with concentrations set based either isolated, PE-MPs group (5 mg L -1 ), GBH group (5 mg L -1 ), or in a group of associated contaminants (GAC), PE-MP + GBH (5 mg L -1  + 5 mg L -1 ). Toxicity effects were evaluated using biochemical, cytogenetic, hematological, and histopathological biomarkers. We observed change in erythrocyte parameters leading to macrocytic normochromic anemia in GAC. Leukocyte parameters indicate a nonspecific immunosuppression caused by the exposure of associated contaminants, besides the attempts to repair damage caused by PE-MPs. Histopathological markers indicate damage to tissues exposed to contaminants. Besides, there were morphophysiological adjustments on gills, with proliferation and hypertrophy of mitochondria-rich cells on GBH and GAC, besides epithelium ruptures, which were mostly present in the exposed groups. Therefore, this study indicates that PE-MPs and GBHs present toxic effects in O. niloticus with the used concentrations, intensified by the association of contaminants. Thus, multi-biomarkers were useful key to verify toxicity, providing data to the investigation of high levels of contaminant's mixture toxicity present in aquatic environments., (© 2024 Wiley Periodicals LLC.)

Microcystins (MC) are hepatotoxic for organisms. Liver MC accumulation and structural change are intensely studied, but the functional hepatic enzymes and energy metabolism have received little attention. This study investigated the liver and hepatocyte structures and the activity of key hepatic functional enzymes with emphasis on energetic metabolism changes after subchronic fish exposure to cyanobacterial crude extract (CE) containing MC. The Neotropical erythrinid fish, Hoplias malabaricus, were exposed intraperitoneally to CE containing 100 μg MC-LR eq kg -1 for 30 days and, thereafter, the plasma, liver, and white muscle was sampled for analyses. Liver tissue lost cellular structure organization showing round hepatocytes, hyperemia, and biliary duct obstruction. At the ultrastructural level, the mitochondria and the endoplasmic reticulum exhibited disorganization. Direct and total bilirubin increased in plasma. In the liver, the activity of acid phosphatase (ACP) increased, and the aspartate aminotransferase (AST) decreased; AST increased in plasma. Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) were unchanged in the liver, muscle, and plasma. Glycogen stores and the energetic metabolites as glucose, lactate, and pyruvate decrease in the liver; pyruvate decreased in plasma and lactate decreased in muscle. Ammonia levels increased and protein concentration decreased in plasma. CE alters liver morphology by causing hepatocyte intracellular disorder, obstructive cholestasis, and dysfunction in the activity of key liver enzymes. The increasing energy demand implies glucose mobilization and metabolic adjustments maintaining protein preservation and lipid recruitment to supply the needs for detoxification allowing fish survival., (© 2022 Wiley Periodicals LLC.)

The flavonoid metal-insecticide [Mg(hesp) 2 (phen)], denominated MgHP, has high potential for controlling agricultural pests. If applied in large scale, it may reach aquatic ecosystems and be harmful to the biota. This study evaluated the effects of MgHP in the gills of the Neotropical fish, Prochilodus lineatus by determining the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione s-transferase (GST), and the levels of glutathione (GSH) and lipid peroxidation (LPO) after 24 and 96 h exposure to 0, 1, 10, 100 and 1000 μg L -1 . The histopathological changes with emphases to mitochondria-rich cells (MRC) were evaluated as well. After 24 h exposure the enzyme activities and the GSH and LPO levels were unchanged however, after 96 h exposure to high MgHP concentration (1000 μg L -1 ), the GST activity and GSH levels increased. Oxidative stress measured as LPO levels did not occur after MgHP exposure in both periods. Gill tissue alterations increased after MgHP exposure to 10, 100 and 1000 μg L -1 . Cellular atrophy, pillar cells changes, filament epithelium hyperplasia and hypertrophy, lamellar epithelium hyperplasia were the most frequent histopathology. MRC in the filament epithelium decreased after exposure to 24 h and increased after 96 h indicating possible transitory osmo-ionic disruption. P. lineatus exhibited high tolerance to MgHP. The increased GST activity and GSH levels after 96 h exposure suggested possible MgHP accumulation and concentration- and time-dependent response. Histopathology in the gills of exposed fish occurred at high MgHP concentrations. These results suggested that the MgHP into water, at high concentrations, affect the gills by changing GST activity, GSH levels and histology being useful biomarkers for MgHP water contamination., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Aquatic ecosystem health is the main concern to increasing pesticides application to control agricultural pests as it is the ultimate receptor of such materials. This study evaluated the impact of new metal-insecticide, the [Mg(hesp) 2 (phen)], referred as MgHP, on fish using physiological, genetic, biochemical, and morphological biomarkers. The fish, Prochilodus lineatus, was exposed to 0 (control), 1, 10, 100, 1000 μg L -1 MgHP, for 24 and 96 h. MgHP was not lethal but caused genotoxicity, altered hematological variables and, the activity of antioxidant and biotransformation enzymes and histology of liver, depending on concentration and time exposure. Hematocrit and erythrocyte number (RBC) increased without change hemoglobin content resulting in changes in hematimetric indexes after 24 h; after 96 h, only RBC was changed. Erythrocyte nuclear abnormalities and crenate cells increased after 24 h but, not after 96 h. Erythrocytes and hepatocytes indicated instability in DNA integrity however, the absence of micronuclei suggested DNA damage repairment. After 24 h, the antioxidant defense system and the phase II biotransformation enzyme was responsiveness and catalase activity decreased at high MgHP concentrations; the antioxidant response was triggered after 96 h. Hepatocyte hypertrophy, intracellular cytoplasmic substances, cytoplasm degeneration, melanomacrophage and hyperemia increased in fish exposed from 10 μg L -1 to higher MgHP concentrations; the organ alteration index increased as MgHP concentration increased showing dose-dependence. Most of hematological and genotoxic effects occurred after 24 h exposure evidencing potential recover capability of organism by activation of the antioxidant defense system and DNA repairment mechanisms. Nevertheless, the histopathological changes in the liver was maintained over time at high MgHP concentrations, a concentration usually no environmental relevant. In conclusion, this data reinforced the importance of continuing research on MgHP effects in other organisms considering the promising use of such compound to control the leaf-cutter ants and other insects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Radiocystis fernandoi, a microcystin (MC) producer, has been common in cyanobacterial blooms in tropical regions. Microcystin is a hepatotoxin that causes tissue damage and even death in animals, including humans; its detoxification process may involve biotransformation and activation of the antioxidant defense system. We evaluated the detoxification pathway, examined the antioxidant defense system responses, and determined the alterations and the organ histopathological indexes in the liver of the tropical fish Hoplias malabaricus after acute and subchronic intraperitoneal exposure to microcystin. The crude microcystin extract of R. fernandoi had predominantly MC-RR and MC-YR. The detoxification process was activated by increasing ethoxyresorufin-O-deethylase activity, whereas glutathione S-transferase was inhibited. The activity of the antioxidant defense enzymes superoxide dismutase (SOD) and glutathione peroxidase decreased after acute exposure; the SOD-catalase system and the glutathione level increased after subchronic exposure. The carbonyl protein level, lipid peroxidation (LPO), and DNA damage were unchanged after acute exposure, whereas protein carbonyl was unchanged, LPO decreased, and DNA damage increased after subchronic exposure. Histopathological alteration indexes differed between acute and subchronic exposure, but the histopathological organ indexes indicate liver dysfunction in both exposure periods. We conclude that MC-RR and MC-YR induce different liver responses depending on the time of exposure, and the antioxidant defense responses after subchronic exposure may help to partially restore the liver function. Environ Toxicol Chem 2020;39:1041-1051. © 2020 SETAC., (© 2020 SETAC.)

Industrial activities and urbanization are the main sources of pollutants in estuarine environments. Diesel, which is widely used in urban and port activities, is an important source of hydrocarbons in the aquatic environment, and its water-accommodated fraction (WAF) is toxic to the local biota. This study was performed to analyze the effects of diesel oil WAF on fish. Specifically, we characterized the gill morphology of the seahorse Hippocampus reidi and analyzed the histopathological changes in the gills after exposure to 50% diesel oil WAF. Acute (12, 24, 48, and 96 h) and subchronic (168 and 336 h) toxicity tests were performed. Furthermore, a recovery protocol was conducted: after exposure to 50% WAF for 168 h, the fish were transferred and kept in seawater without contaminants for 336 h, for a total experimental period of 504 h. The seahorse branchial apparatus was found to be tufted with short filaments; the apical surfaces of the pavement cells in the filament and lamellar epithelia formed "crests" and had microridges. Mitochondria-rich cells were distributed exclusively in the lamellar epithelium, while mucous cells were distributed in the filament epithelium. All pathologies observed after acute and subchronic exposure featured progressive time-dependent alterations of lamellar structure that might disrupt gill physiological and metabolic functions. During the recovery period, the gill alterations were gradually repaired., (Copyright © 2019. Published by Elsevier Ltd.)

Blooms of cyanobacteria, a common event in eutrophic environments, result in the release of potentially toxic substances into the water. The cyanobacterium Radiocystis fernandoi produces microcystin (MC) and other peptides that may disturb homeostasis. This study evaluated the effect of intraperitoneal injections containing the crude extract (CE) of R. fernandoi strain R28 on the gills and kidneys of neotropical fish, Piaractus mesopotamicus, 3, 6 and 24 h post-injection. CE contained MC-RR, MC-YR and minor other oligopeptides. Plasma ions and the activities of the enzymes PP1 and PP2A, Na + /K + -ATPase (NKA), H + -ATPase (HA) and carbonic anhydrase (CA) were determined and morphological changes in both the gills and kidneys were characterized. Compared to controls, the concentration of Na + within the plasma of P. mesopotamicus decreased after treatment with CE 3 h post treatment and increased after 24 h; the concentration of K + decreased after 6 h. The activity of the endogenous PP1 and PP2A was unchanged in the gills and was inhibited in the kidneys 6 h after i.p. injection. In the gills, NKA activity increased after 3 h and decreased 6 h post i.p. exposure. Further, NKA activity did not differ from the controls 24-h post injection. In the kidneys, NKA, HA and CA activities were unaffected by treatment. The mitochondria-rich cell (MRC) density in the gills decreased after 3 h in the filament and 3 and 6 h in the lamellae and was restored to the control levels 24 h post-exposure. Filament epithelial hyperplasia and hypertrophy, lamellar atrophy and rupture of the lamellar epithelium were the most common effects of treatment in the gills. No histopathological changes occurred in the kidneys. This study demonstrates that a single dose of toxic CE from R. fernandoi can cause a transitory ion imbalance in P. mesopotamicus which is related to the changes in MRC levels and NKA activity. Ionic balance was recovered 24 h post i.p. injection, however, morphological changes that occurred in the gills took a longer amount of time to return to normal. To conclude, the effects of components contained within the CE of R. fernandoi may be harmful to P. mesopotamicus. In particular, the recovery of ionic regulation depends on MRC responses and histopathological changes produced by CE may affect gas exchange and other gill functions., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The cyanobacterium Radiocystis fernandoi has been frequently identified in cyanobacterial blooms in Brazil. Recently, R. fernandoi strain R28, which produces microcystin (MC)-RR and MC-YR, was isolated from the Furnas reservoir, Minas Gerais, Brazil. The present study evaluated the hematological variables and erythrocyte antioxidant responses, lipid peroxidation (LPO), and genotoxicity in a neotropical fish (Hoplias malabaricus) after acute and subchronic exposure to a crude extract (CE) of R. fernandoi strain R28. Acute exposure (12 or 96 h) consisted of a single intraperitoneal (i.p.) CE injection, and subchronic exposure consisted of one i.p. CE injection every 72 h for 30 days. After acute exposure, fish exhibited macrocytic anemia (12 h post-injection) followed by normocytic anemia (96 h post-injection). The increased activity of superoxide dismutase, glutathione peroxidase, glutathione-S-transferase, and the glutathione level in the erythrocytes did not prevent oxidative stress, manifested as lipid peroxidation and elevated DNA damage after acute exposure. After subchronic exposure, the hematological variables recovered, and the absence of erythrocyte oxidative stress suggests possible modulation by other biological factors, including a possible decrease in MC uptake by the cells and/or increasing detoxification efficiency that precludes erythrocyte damage., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Cyanobacterial proliferation in river and lakes is the result of eutrophication. The cyanobacterium Radiocystis fernandoi strain R28 produces mostly two MC variants MC-RR and MC-YR and small amounts of other oligopeptides, but does not produce MC-LR. The present study investigated the hepatotoxic potential of the crude extract of the R. fernandoi strain R28 on the Neotropical fish, Piaractus mesopotamicus, at 3, 6, and 24 h after intraperitoneal injection (100 μg MC-LR equivalent per kg -1 body mass) using biochemical and morphological biomarkers of liver damage. Although the protein phosphatases PP1 and PP2A were not inhibited during the 24-h treatment, liver parenchyma and hepatocyte structure were disrupted. Alkaline phosphatase increased at 3 h post-injection and decreased after 24 h; alanine aminotransferase and aspartate aminotransferase increased in a time-dependent manner up to 24 h indicating impaired liver function. Progressive histopathological changes were consistent with biochemical results demonstrating alterations in liver structure and function. In conclusion, the crude extract of R. fernandoi strain R28 has high hepatotoxic potential and can severely compromise fish health.

Petroleum hydrocarbons are one of the primary organic chemicals found in water bodies, and the water-soluble fraction of petroleum (WSFP) may be responsible for much of the toxic effects. In the present study, genotoxicity assays and histopathological analysis of the gills were analyzed for two experimental protocols: 1) Juvenile Centropomus parallelus were exposed to different concentrations of WFSP (0%, 25%, 50% and 75%) for 96h; 2) A second fish group was exposed to 50% WFSP for 168h followed by a post-exposure period for 168h in clean water (recovery). The total benzene, toluene, ethyl benzene and xylene (BTEX) and polycyclic aromatic hydrocarbon (PAH) concentrations at time 0 were 254μgL -1 and 4.72μgL -1 in 25%; 552.9μgL -1 and 9.36μgL -1 in 50%; and 842.4μgL -1 and 9.97μgL -1 in 75% WSFP, respectively. Based on the alkaline comet assay, the damage index (DI) values of fish exposed to 25% WSFP for 96h were significantly higher than those in the control group, and in the micronucleus test, the higher damage values were found in fish exposed to 75% WSFP. Furthermore, this last genotoxic test showed recovery after 168h. At all concentrations of WSFP, several histopathological changes were observed, and overall, most of these changes observed in the gills were classified as proliferative changes and represented a protective mechanism against pollutant uptake. Based on the recovery experiment, the damage was also significantly reduced after recovery. Our results showed that short-term exposure to WSFP compounds triggered cellular alterations in C. parallelus, but total recovery did not occur with time. Additionally, the different periods of exposure were not sufficient to induce severe gill damage in C. parallelus. Moreover, this fish demonstrated its usefulness as a sentinel species., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The toxicological effect of cellular extract of cyanobacterium Radiocystis fernandoi strain R28 containing RR and YR microcystins was analyzed in the fish Hoplias malabaricus with emphasis on the liver structure and energetic metabolism, after short-term exposure. Fish were intraperitoneally (i.p.) injected with 100 μg of equivalent MC-LR kg -1 body mass containing in the cellular extract of R. fernandoi strain R28. Twelve and 96 h post-injection, the plasma, liver and white muscle were sampled for biochemical analyses and liver was also sampled for morphological analyses. After i.p. injection, the activity of acid phosphatase (ACP), alanine aminotransferase (ALT) and direct bilirubin increased in the plasma, while ALT and aspartate aminotransferase (AST) decreased in the liver. Glucose, lactate and pyruvate increased while protein decreased in the plasma; glycogen, pyruvate and lactate decreased in the liver; and glycogen and glucose increased in the muscle. Ammonia increased in the plasma, liver and muscle. The hepatocyte cell shape changed from polyhedral to round after cellular extract injection; there was loss of biliary canaliculus organization, but the biliary duct morphology was conserved in the liver parenchyma. In conclusion, microcystins present in the cellular extract of R. fernandoi strain R28 affect the liver structure of H. malabaricus, but the liver was able to continuously produce energy by adjusting its intermediate metabolism; glycogenolysis and gluconeogenesis maintained glucose homeostasis and energy supply., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Radiocystis fernandoi R28 strain is a cyanobacterium which produces mostly the RR and YR microcystin variants (MC-RR and MC-YR, respectively). The effects of crude extract of the R. fernandoi strain R28 were evaluated on the protein phosphatases and on the structure and ultrastructure of the liver of the Neotropical fish, Hoplias malabaricus, after acute and subchronic exposure. Concomitantly, the accumulation of the majority of MCs was determined in the liver and muscle. The fish were exposed to 120.60 MC-RR+MC-LR kg-fish -1 (=100μg MC-LReq kg-fish -1 ) for 12 and 96h (one single dose, acute exposure) and 30days (one similar dose every 72h, subchronic exposure). MCs did not accumulate in the muscle but, in the liver, MC-YR accumulated after acute exposure and MC-RR and MC-YR accumulation occurred after subchronic exposure. Protein phosphatase 2A (PP2A) activity was inhibited only after subchronic exposure. Acute exposure induced liver hyperemia, hemorrhage, changes in hepatocytes and cord-like disorganization. At the ultrastructural level, the decreasing of glycogen and lipid levels, the swelling of mitochondria and whirling of endoplasmic reticulum suggested hepatocyte necrosis. Subchronic exposure resulted in a complete disarrangement of cord-like hepatocytes, some recovery of mitochondria and whirling endoplasmic reticulum and extensive connective tissues containing fibrous materials in the liver parenchyma. Despite microcystin toxicity and liver alterations, no tumor was induced by MCs. In conclusion, the increased algal mass of R. fernandoi in tropical freshwater, producing mainly MC-RR and MC-YR variants, results in fish liver impairments., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study evaluates the contaminants in water and their bioaccumulation in the gills and liver of two ecologically distinct fish species, Astyanax fasciatus and Pimelodus maculatus, living in the reservoir of the Furnas hydroelectric power station located in Minas Gerais in the southeastern Brazil. The histological alterations in these organs are also examined. Water and fish were collected in June and December from five sites (site 1: FU10, site 2: FU20, site 3: FU30, site 4: FU40 and site 5: FU50) in the reservoir, and agrochemicals and metals selected based on their use in the field crops surrounding the reservoir were analyzed in the water and in the fish gills and livers. The concentrations of the organochlorines aldrin/dieldrin, endosulfan and heptachlor/heptachlor epoxide as well as the metals copper, chromium, iron and zinc in the gills and livers of both fish species were higher in June than in December; the liver accumulated higher concentrations of contaminants than the gills. The organochlorine metolachlor was detected only in the liver. The histological pattern of changes was similar in both species with regard to contaminant accumulation in the gills and liver. Fish from FU10, the least contaminated site, exhibited normal gill structure and moderate to heavy liver damage. Fish collected at FU20 to FU50, which were contaminated with organochlorines and metals, showed slight to moderate gill damage in June and irreparable liver damage in the livers in June and December. The histological changes in the gills and liver were suitable to distinguishing contaminated field sites and are therefore useful biomarkers for environmental contamination representing a biological end-point of exposure., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The present study investigated the structural changes in the rat calcaneal tendon (CT), superficial flexor tendon (SFT), and deep flexor tendon (DFT) in response to jump exercises and anabolic androgenic steroids (AAS). Animals were divided into four groups: sedentary, trained, AAS-treated sedentary rats, and AAS-treated trained animals. Training increased the volume density (Vv%) of blood vessels in all regions of the CT and DFT, cell Vv% in the peritendinous sheath of the proximal and distal regions of the SFT and proximal region of DFT, and cell Vv% in the tendon proper of the proximal and distal regions of the SFT and DFT. The combination of AAS and load exercises showed little increased blood vessel Vv% at the proximal region of the CT, intermediate region of the SFT, and all regions of the DFT as opposed to an increase in adipose cell Vv% in the CT proximal region. The AAS reduced the levels of hydroxyproline in the proximal region of the DFT and in the distal region of the STF. In conclusion, exercise promoted benefits to the adaptation of the tendons to overload. These effects were absent when load exercise was combined with AAS. The abusive consumption of AAS contributes to tendon inertness and rigidity, and increases the potential risk of injury., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

This study investigated the relationship between contaminant body burden and the oxidative stress status of the gills and livers of two wild fish species in the Furnas Hydroelectric Power Station (HPS) reservoir (Minas Gerais, Brazil). Gills and livers presented similar pathways of metals and organochlorine bioaccumulation. During June, organochlorines were associated with lipid peroxidation (LPO), indicating oxidative stress due to the inhibition of the antioxidant enzymes superoxide dismutase and glutathione peroxidase. In the most polluted areas, metal concentrations in the liver were associated with metallothionein. During December, contaminants in the gills and liver were associated with catalase activity and LPO. Aldrin/dieldrin was the contaminant most associated with oxidative damage in the livers of both species. This integrated approach shed light on the relationship between adverse biological effects and bioaccumulation of contaminants inputted by intensive agricultural practices and proved to be a suitable tool for assessing the environmental quality of man-made reservoirs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Through integrating chemical, biochemical and morphological analyses, this study investigated the effects of multiple pollutants on the gill mitochondria-rich cells (MRCs) in two fish species, Astyanax fasciatus and Pimelodus maculatus, collected from five sites (FU10, FU20, FU30, FU40 and FU50) in the Furnas Hydroelectric Power Station reservoir. Water analyses revealed aluminum, iron and zinc as well as organochlorine (aldrin/dieldrin, endosulfan, heptachlor/heptachlor epoxide and metolachlor) contamination at all of the sites, with the exception of FU10. Copper, chrome, iron and zinc were detected in the gills of both species, and aldrin/dieldrin, endosulfan and heptachlor/heptachlor epoxide were detected in the gills of fish from all of the sites, with the exception of FU10. Fish collected at FU20, FU30 and FU50 exhibited numerous alterations in the surface architecture of their pavement cells and MRCs. The surface MRC density and MRC fractional area were lower in fish from FU20, FU30, FU40 and FU50 than in those from the reference site (FU10) in the winter, and some variability between the sites was observed in the summer. The organochlorine contamination at FU20 and FU50 was associated with variable changes in the MRCs and inhibition of Na(+)/K(+)-ATPase (NKA) activity, especially in P. maculatus. At FU30, the alterations in the MRCs were associated with the contaminants present, especially metals. A multivariate analysis demonstrated a positive association between the biological responses of both species and environmental contamination, indicating that under realistic conditions, a mixture of organochlorines and metals affected the MRCs by inhibiting NKA activity and inducing morphological changes, which may cause an ionic imbalance., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The present article investigates the responses of Hippocampus reidi exposed to crude oil (10mL/L) for time periods that are characteristic of acute (12, 24, 48 and 96h) and subchronic (168 and 336h) and its recovery at 168h, such as to assess H. reidi as a good sentinel species. These responses were examined by genotoxic and morphologic analyses. There was a control group (n=8) for each group exposed to crude oil (n=8). The results revealed the occurrence of genotoxic damage in erythrocytes of all specimens exposed to crude oil. The damage index (DI) observed for all exposure times were significantly higher compared to those of the respective control groups; the highest DI was observed in specimens exposed to crude oil for 168h. The group exposed to crude oil for 96h had the highest values of micronuclei than all other exposure times. Microscopic inspection of the H. reidi gills revealed the presence of several histopathological changes, all of which were minor severity (structural normal gills). The recovery experiment revealed a significant reduction in genotoxic damages, however the period of 168h was not sufficient to recuperate the histopathology damages. The Seahorse has presented significant genotoxic responses after exposure to crude oil. Furthermore, it is a sedentary fish and is widely distributed; in conclusion this specie can be considered an excellent sentinel organism., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The aim of this study was to determine the acute toxicity of Roundup(®) Ready (RR) in Piaractus mesopotamicus, and evaluate the effects on the morphology of the gills and liver of exposed surviving fish. Fish were exposed to 3.0, 3.5, 4.0 and 4.5mgL(-1) of glyphosate, and the LC(50);48h was estimated at 3.74±0.2mgL(-1). Gill histopathology was rare, and the activity of Na(+)/K(+)-ATPase enzyme did not change, suggesting normal function. However, the damage to the liver was classified as moderate to severe. Cytoplasmic vacuolization, lipid accumulation, nuclear and cellular membrane alterations and glycogen depletion were found in the liver, suggesting a reduction in the liver function. The glyphosate in the RR formulation was classified as moderately toxic for P. mesopotamicus, and the severe damage in the liver may affect the detoxification and/or tissue repair process and contribute to fish death., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The impact of acute (48 h) and subchronic (14 days) exposures to environmentally realistic atrazine concentrations (2, 10 and 25 μg L(-1)) were evaluated on the gills of Prochilodus lineatus by assessing the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), the levels of reduced glutathione (GSH) and lipid peroxide (LPO) as well as the histopathological damage. Acute and subchronic exposure to atrazine at 2 or 25 μg L(-1) did not change the activities of GST, SOD, CAT or GPx or the concentrations of GSH and LPO; however, subchronic exposure to 10 μg L(-1) increased the activity of GST, SOD and CAT and the LPO level. Histopathological indexes indicated normal gill function with scattered epithelial changes after acute and chronic exposure to 2 or 10 μg L(-1) of atrazine; however, fish chronically exposed to 25 μg L(-1) of atrazine, although had scattered lesions, the severity of lesions resulted in slightly to moderately gill damage. Acute exposure to atrazine decreased the type 3 MCs (containing acid mucosubstances with sulfate esters) in fish exposed to 2 or 10 μg L(-1) and increased the type 4 MCs (containing all types of mucosubstances) in fish exposed to 25 μg L(-1). Chronic exposure to atrazine reduced the type 3 MCs in fish exposed to 10 or 25 μg L(-1). The gills showed a low sensitivity to atrazine after acute exposure. However, the persistence of atrazine in water (subchronic exposure) promoted an increase of LPO levels in the gills and increased the frequency and severity of histopathological changes. The decreased density of type 3 MCs in fish exposed to atrazine suggests a mechanism to wash toxic substances away from the gill surface., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The effects of the herbicide atrazine on the gill of the freshwater fish Prochilodus lineatus were evaluated after exposure of fish to 2, 10 and 25 μg L(-1) atrazine during 48 h (acute exposure) and 14 d (subchronic exposure). Ions and osmolality were measured in plasma and gill samples were taken to determine the Na(+)/K(+)-ATPase (NKA) and carbonic anhydrase (CA) activities and for morphological analysis. Plasma osmolality and Na(+) and Cl(-) ions changed depending on atrazine concentration, but atrazine exposure had no effect on the Na(+)/Cl(-) ratio. NKA activity did not change after atrazine exposure, but CA activity decreased in fish exposed to 25 μg L(-1) for 14 d. Gill MRC density decreased after acute exposure but did not change in fish exposed to the subchronic treatment. The MRC density at the epithelial surface increased in fish exposed to 25 μg L(-1), and the MRC fractional area (MRCFA) increased in fish exposed to 10 μg L(-1). The changes in MRCs provide evidence of morphological adjustments to maintain ionic homeostasis in spite of the inhibition of CA activity at the highest atrazine concentration., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The condition factor and blood variables, including erythrocyte lipid peroxidation (LPO) and the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), in two ecologically distinct fish species (Astyanax fasciatus and Pimelodus maculatus) were evaluated at five sites in the Furnas Hydroelectric Power Station reservoir (Brazil) to assess water quality. Aldrin/dieldrin, endosulfan, heptachlor epoxide, and metolachlor were detected at different concentrations in four of the sites. Condition factor was not directly affected by such contaminants. A negative correlation between hematocrit and heptachlor was detected in P. maculatus. Positive correlations between red blood cells and heptachlor as well as an interactive effect of metolachlor and aldrin/dieldrin were detected in A. fasciatus. The erythrocytes of both species collected from the contaminated sites showed high levels of LPO, an increase in SOD and GPx activities and a decrease in CAT activity. Although the leukocyte number and the differential percentage of leukocytes varied among the sites, the hematological variables, the LPO levels, and the antioxidant enzyme activities could be used to assess water quality, regardless of the differences in the responses of the fish species.

Hypoxia events are common in many aquatic systems, which may be a natural event or provoked by anthropogenic actions, as well as accidents involving oil occurring throughout the world are frequent. Thus, through the possibility of occurrence of these two situations in same place the purpose of this study was to evaluate if damage caused by crude oil on genotoxic and morphological parameters in the marine fish species Hippocampus reidi will be aggravated by events of severe hypoxia. Sea horses were exposed during 8h to the following conditions: crude oil (OIL), severe hypoxia (HYP), association of severe hypoxia and crude oil (HYP+OIL) and normoxia without contaminant (CONT). An increase in micronuclei observed in OIL and HYP+OIL groups indicates that the crude oil exposure was a determining factor in the micronuclei induction and hypoxia did not intensify this result. In comet assays, both petroleum and hypoxia provoke DNA damage. The most frequent histopathology in the control groups and in those exposed to OIL and HYP+OIL groups were: hypertrophy and capillary dilation; hypertrophy and hyperplasia; hypertrophy, epithelial "lifting" and epithelial hyperplasia. An elongation of the lamellae was observed in fish from the two groups exposed to hypoxia, probably due to the fact that these groups required a greater flow of blood in the gills to increase the efficiency of gas exchange, since they were in a hypoxic environment. In summary, the micronuclei test and comet assay can be used as a good biomarker of contamination by petroleum. The association of hypoxia with crude oil in some aspects may exacerbate the responses of fish, in the light of the increase in DNA damage and the alterations in thickness of the gill epithelium., (2011 Elsevier Inc. All rights reserved.)