M.G. Paulino

Subchronic exposure to atrazine induces biochemical and histopathological changes in the gills of a Neotropical freshwater fish, Prochilodus lineatus.

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.

Acute exposure of a glyphosate-based herbicide affects the gills and liver of the Neotropical fish, Piaractus mesopotamicus

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.

Effects of atrazine on the gill cells and ionic balance in a neotropical fish, Prochilodus lineatus.

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.

The impact of organochlorines and metals on wild fish living in a tropical hydroelectric reservoir: bioaccumulation and histopathological biomarkers.

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.

Integrated use of antioxidant enzymes and oxidative damage in two fish species to assess pollution in man-made hydroelectric reservoirs

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.

Organochlorines and metals induce changes in the mitochondria-rich cells of fish gills: An integrative field study involving chemical, biochemical and morphological analyses

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.

Using condition factor and blood variable biomarkers in fish to assess water quality

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.

Crude extract of cyanobacteria (Radiocystis fernandoi, strain R28) induces liver impairments in fish.

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.

Genotoxic and morphological damage in Hippocampus reidi exposed to crude oil

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.

Tendon structural adaptations to load exercise are inhibited by anabolic androgenic steroids

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.