Use of hepatocytes from Hoplias malabaricus to characterize the toxicity of a complex mixture of lipophilic halogenated compounds

Co-exposure effects of lead and TiO2 nanoparticles in primary kidney cell culture from the freshwater fish Hoplias malabaricus

This study evaluated the effects of Lead (Pb) and titanium dioxide nanoparticles (TiO₂ NPs) alone or in combination in anterior kidney macrophages of the freshwater fish Hoplias malabaricus, naïve or stimulated with 1ng.mL^-1 lipopolysaccharide (LPS). Pb (1×10^-5 to 1×10^-1mg.mL^-1) or TiO₂ NPs (1.5×10^-6 to 1.5×10^-2mg.mL^-1) reduced cell viability despite LPS stimulation, especially Pb 10^-1mg.mL^-1. In combination, lower concentrations of NPs intensified Pb-induced cell viability reduction while higher concentrations restored the cell viability independently of LPS stimulation. Basal and LPS- induced NO production was reduced by both TiO2 NPs and Pb isolated. The combination of both xenobiotics avoided this reduction of NO production by the isolated compounds at lower concentrations but the protective effect was lost as the concentrations increased. None xenobiotic increase DNA fragmentation. Therefore, at specific conditions, TiO₂ NPs may have a protective effect over Pb toxicity, may also provide additional toxicity at higher concentrations.

Metal loads and biomarker suite responses in a tropical carnivorous fish indicative of anthropogenic impacts in a Southeastern Brazilian lagoon

Tropical coastal lagoons are highly productive environments exhibiting high biodiversity. However, the use of these ecosystems by local communities is of concern, since this generally leads to environmental degradation. The Imboassica coastal lagoon, located in Macaé city, in Northern Rio de Janeiro, is an important ecosystem in the state, however, already displaying signs of anthropogenic impacts. Carnivorous fish Hoplias malabaricus specimens were sampled from this impacted site, as well as from a reference area. Fish from Imboassica Lagoon presented lower condition factor, lower cholinesterase activity, and higher percentage of erythrocyte micronuclei when compared to fish from the reference site. Metals in fish from Imboassica Lagoon were always higher than Encantada Lagoon, with some seasonal differences, where some metals were higher in the rainy season compared to the dry season in muscle tissue, with the exception of Cu, Fe, Sr, and Zn; and in the liver, except for Ba, Cd, Cr, Ni, and Sr. Cr and Mn in the edible muscle portion of the fish were higher than the limits established by Brazilian and International legislations as permissible for human consumption, thus leading to concerns regarding public health risks for the local population that use fish as their main protein source.

Comparative bioaccumulation and effects of purified and cellular extract of cylindrospermopsin to freshwater fish Hoplias malabaricus

Many tropical freshwater ecosystems are impacted by cyanobacteria blooms increasing the risk of cyanotoxins exposure to aquatic organisms while human populations may be exposed by eating fish, drinking water, or dermal swimming. However, few toxicological data are available on the influence of cyanobacteria blooms in particular, cylindrospermopsin (CYN) on Brazilian neotropical fish. A number of studies demonstrated the ability of CYN to bioaccumulate in freshwater organisms and consequently enter the human food chain. The aim of the current study was to examine the effects of CYN following single intraperitoneal injection (50 µg/kg) of purified CYN (CYNp) or aqueous extract of CYN-producing cyanobacteria extract (CYNex) after 7 or 14 days. Biomarkers such as histopathology (liver), oxidative stress (liver and brain), and acetylcholinesterase (AChE) activity (muscle and brain) were utilized in order to assess the influence of CYN on Hoplias malabaricus. In terms of AChE activity, administration of CYNex and CYNp both muscle and brains were used as target tissues. In brain an increase of glutathione S-transferase (GST) activity and lipid peroxidation (LPO) levels was noted suggesting an imbalance in redox cycling. The majority of biomarkers did not present significant alterations in liver, but an elevation in superoxide dismutase (SOD) and glucose 6 phosphate dehydrogenase (G6PDH) activities was found. Different profiles of GST activity were observed in both studied groups (CYNex and CYNp) while LPO (CYNex and CYNp) and protein carbonylation (PCO) (CYNp) levels increased after exposure to CYN. The incidence of necrosis, melanomacrophages centers, and free melanomacrophages were detected as evidence of cell death and immune responses. Nonprotein thiols (NPT) levels were not markedly affected in both exposed groups. Data demonstrated that in vivo exposure to CYN produced biochemical and morphological disturbances in liver and brain of H. malabaricus.

Cylindrospermopsin effects on cell viability and redox milieu of Neotropical fish Hoplias malabaricus hepatocytes

Cylindrospermopsin (CYN) is a cyanotoxin that is cytotoxic to a wide variety of cells, particularly to the hepatocytes. In this study, the toxic effects of purified CYN were investigated in primary cultured hepatocytes of Neotropical fish Hoplias malabaricus. After isolation, attachment, and recovery for 72 h, the cells were exposed for 72 h to 0, 0.1, 1.0, 10, and 100 μg l^-1 of CYN. Then, cell viability and a set of oxidative stress biomarker responses were determined. Catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione S-transferase activities were not affected by exposure to CYN. Concentration-dependent decrease of glutathione reductase activity occurred for most CYN-exposed groups, whereas non-protein thiol content increased only for the highest CYN concentration. Lipid peroxidation, protein carbonylation, and DNA damage levels were not altered, but reactive oxygen species levels increased in the cells exposed to the highest concentration of CYN. Cell viability decreased in all the groups exposed to CYN. Thus, CYN may cause a slight change in redox balance, but it is not the main cause of cell death in H. malabaricus hepatocytes.

Saxitoxins induce cytotoxicity, genotoxicity and oxidative stress in teleost neurons in vitro

The aim of this study was establish a protocol for isolation and primary culture of neurons from tropical freshwater fish species Hoplias malabaricus for assessment of the effects of neurotoxic substances as saxitoxins (STXs). Cells from brain of H. malabaricus were treated with different concentrations of trypsin, dispase and papain for tissue dissociation. Cells type was separated by cellular gradient and basic fibroblast growth factor (bFGF) supplement nutrition media were added. The dissociated cells were plated with medium and different STXs concentrations and the toxic cellular effects such as oxidative stress, neurotoxicity, and genotoxicity and apoptosis process were evaluated. Cultures treated with bFGF showed the greatest adherence, survival and cellular development. STXs increased specific activity of glutathione peroxidase and lipoperoxidation levels, were cytotoxic and genotoxic indicated by the comet assay. Although the STXs effects due the blockage of sodium channels is reported to be reversible, the time exposure and concentration of STXs suggested cellular injuries which can lead to neuropathology. The establishment of primary neuronal culture protocol enables new applications for neurotoxicological assessments.

Increased liver apoptosis and tumor necrosis factor expression in Atlantic bluefin tuna (Thunnus thynnus) reared in the northern Adriatic Sea

The Atlantic bluefin tuna Thunnus thynnus (ABFT) is intensely fished in the Mediterranean Sea to supply a prosperous capture-based mariculture industry. Liver apoptotic structures and tumor necrosis factor (TNF) gene expression were determined in: wild ABFT caught in the eastern Atlantic; juvenile ABFT reared in the central Adriatic Sea; juvenile ABFT reared in the northern Adriatic Sea; adult ABFT reared in the western Mediterranean. The highest density of liver apoptotic structures was found in the juveniles from the northern Adriatic. Two partial TNF cDNAs (TNF1 and TNF2) were cloned and sequenced. TNF1 gene expression was higher in juveniles than in adults. The highest expression of TNF2 was found in the juveniles from the northern Adriatic. These findings might be related to the juvenile exposure to environmental pollutants.

Water quality assessment of the Tubarão River through chemical analysis and biomarkers in the Neotropical fish Geophagus brasiliensis

The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.

Trichlorfon-induced apoptosis in hepatocyte primary cultures of Carassius auratus gibelio

Trichlorfon, an organophosphorus pesticide, can disrupt metabolism, reproduction and immune functions of some aquatic animals. In the present study, the effect of trichlorfon on apoptosis and the underlying apoptotic mechanism were investigated in primary cultures of Carassius auratus gibelio hepatocytes. Analyses of cultures exposed to 0, 0.01, 0.1, and 1.0 mg L(-1) trichlorfon concentrations for 24h indicated that trichlorfon induced apoptosis and caused nuclear shrinkage, cell membrane rupture, cytoskeletal collapse, loss of cytoplasm, mitochondria vacuolization, and apoptotic body formation, as well as lipid droplet accumulation. Trichlorfon increased intracellular reactive oxygen species and malondialdehyde concentrations and caused cytochrome c release from mitochondria into the cytoplasm, leading to caspase-3 activation. These findings contributed to a better understanding of the mechanisms underlying trichlorfon-induced apoptosis via activation of mitochondrial pathways while clearly indicating that trichlorfon-induced cell death was via apoptosis accompanied by mitochondrial cytochrome c release and consequent caspase-3 activation.

Evaluation of waterborne exposure to oil spill 5 years after an accident in Southern Brazil

Fish (Astyanax sp.) were exposed to water samples from the Arroio Saldanha, locality of an oil spill, and the Barigui River (upstream and downstream of the confluence of the river and Arroio Saldanha), Brazil. Histopathological and biochemical biomarkers, as acetylcholinesterase (AchE), ethoxyresorufin-O-deethylase (EROD), catalase (CAT), glutathione-S-transferase (GST) activities, lipid peroxidation (LPO) levels, and amounts of polynuclear aromatic hydrocarbon residues (PAHs) in bile were evaluated. PAHs, metals, and surfactants were investigated in the water samples. CAT and GST activities increased in the Arroio Saldanha sample, whereas CAT activity and LPO levels were increased in the upstream and downstream sites. The results suggested a toxic action of the free radicals and disturbance of the antioxidant defense mechanisms. However, the EROD and AchE activities were not affected. Histopathology studies showed severe lesions. The oil is still bioavailable to biota, moreover, other pollution sources continue to affect the water in the Barigui River.

Toxic effects of DDT and methyl mercury on the hepatocytes from Hoplias malabaricus

Here, we examined the impact of dichlorodiphenyltrichloroethane (DDT) and monomethyl mercury (MeHg) on the redox milieu and survival of hepatocytes from Hoplias malabaricus (traíra). After isolation and attachment of cells, we established one control and four treatments: DDT (50nM of DDT), MeHg I (0.25microM of MeHg), MeHg II (2.5microM of MeHg) and DDT * MeHg I (combination of 50nM of DDT and 0.25microM of MeHg). After four days the exposed hepatocytes presented significantly increased damage in lipids (all treatments), proteins (DDT * MeHg I and MeHg II) and reduced cell viability (all treatments). Also the antioxidant enzymes catalase, glucose-6-phosphate dehydrogenase (G6PDH), glutathione reductase and superoxide dismutase were affected. The current data showed that despite of some protective responses, the increased disturbs on membrane lipids and proteins, increased hydrogen peroxide levels, and decreased glutathione concentration and cell viability strongly indicate oxidative stress as the reason of hepatotoxicity due to DDT and MeHg exposure. In addition, DDT and MeHg together had greater effect than alone when G6PDH and glutathione-S-transferase activities and lipids damage were considered. These findings are indicative of hepatotoxicity occurring at realistic concentrations of DDT and MeHg found in Amazonian fish tissues.