The exposure to a world-wide used herbicide atrazine (ATZ) (96h exposure to 2, 10, and 100μgL−1), was investigated on the freshwater fish Rhamdia quelen through a multi biomarker approach. Liver ...histopathology revealed leukocyte infiltration, hepatocyte vacuolization like steatosis and necrosis areas, leading to raised lesion index levels in all tested concentrations. The increase of free melanomacrophage numbers was observed. Gill filaments revealed considerable loss of the microridges on pavement cells at 10 and 100μgL−1 of ATZ, and a significantly increased of chloride cell (CC) number and density on apical surface area at 100μgL−1 of ATZ. CAT, GST, GPx, and GR activities were inhibited by all tested concentrations. GSH levels were reduced in individuals exposed to 100µgL−1. Osmoregulatory function was also disturbed. We observed an increase of plasma magnesium concentrations at 10µgL−1. Additionally the inhibition of branchial carbonic anhydrase activity was observed at 100µgL−1. In the kidney, carbonic anhydrase activity decreased only in the group exposed to 2µgL−1. These results suggest that ATZ, represents a potential ecotoxicological hazard and can be hepatotoxic and nephrotoxic even low concentrations. The current study was the first to show the nephrotoxic effect of ATZ in fish. Besides, in Brazil, the environmental protection agency (CONAMA) establishes that the maximum allowed level of dissolved ATZ in water is 2μgL−1, but the present results showed that this concentration may cause histopathological, biochemical and physiological changes in R. quelen.
•Silver catfish health can be compromised on atrazine contaminated water.•Atrazine can be hepatotoxic and nephrotoxic.•The liver showed relevant biochemical, histopathological and physiological changes.•Gills showed changes in pavement cells and chloride cells.•The limit of 2μgL−1 allowed by Brazilian legislation is not safe to R. quelen.
Reactive oxygen species (ROS) produced by NADPH phagocyte oxidase isoform (NOX2) are critical for the elimination of intracellular pathogens in many infections. Despite their importance, the role of ...ROS following infection with the eukaryotic pathogen
has not been fully elucidated. We addressed the role of ROS in C57BL/6 mice following intradermal infection with
Despite equivalent parasite loads compared with wild-type (WT) mice, mice deficient in ROS production by NOX2 due to the absence of the gp91 subunit (gp91
) had significantly more severe pathology in the later stages of infection. Pathology in gp91
mice was not associated with alterations in CD4
T cell-mediated immunity but was preceded by enhanced neutrophil accumulation at the dermal infection site. Ex vivo analysis of infected versus uninfected neutrophils revealed a deficiency in infection-driven apoptosis in gp91
mice versus WT mice. gp91
mice presented with higher percentages of healthy or necrotic neutrophils but lower percentages of apoptotic neutrophils at early and chronic time points. In vitro infection of gp91
versus WT neutrophils also revealed reduced apoptosis and CD95 expression but increased necrosis in infected cells at 10 h postinfection. Provision of exogenous ROS in the form of H
O
reversed the necrotic phenotype and restored CD95 expression on infected gp91
neutrophils. Although ROS production is typically viewed as a proinflammatory event, our observations identify the importance of ROS in mediating appropriate neutrophil apoptosis and the importance of apoptosis in inflammation and pathology during chronic infection.
As it is the case in all animal food production systems, it is often necessary to treat farmed fish for diseases and parasites. Quite frequently, fish farmers still rely on the aggressive use of ...copper to control bacterial infections and infestations by ecto-parasites, and to manage the spread of diseases. The susceptibility of the neotropical fish Rhamdia quelen to copper was here evaluated at different waterborne copper concentrations (2, 7 or 11μgCuL−1) for 96h, through a multi biomarkers approach. Liver histopathological findings revealed leukocyte infiltration, hepatocyte vacuolization and areas of necrosis, causing raised levels of lesions upon exposure to 7 and 11μgCuL−1. Decreased occurrence of free melano-macrophages and increased densities of melano-macrophage centers were noted upon exposure to 11μgCuL−1. Gills showed damages on their secondary lamellae already at 2μgCuL−1; hypertrophy and loss of the microridges of pavement cells at 7 and 11μgL−1, and increased in chloride cell (CC) apical surface area (4.9-fold) and in CC density (1.5-fold) at 11μgCuL−1. In the liver, catalase (CAT), glutathione peroxidase activities (GPx) and glutathione concentration (GSH) remained unchanged, compared to the control group. However, there was inhibition of 7-ethoxyresorufin-O-deethylase (EROD) at all copper concentrations tested. Glutathione reductase activity (GR) was reduced and levels of lipid peroxidation (LPO) were increased at 11μgCuL−1. Glutathione S-transferase activity (GST) at 7μgCuL−1 and superoxide dismutase activity (SOD) at both 7 and 11μgCuL−1 were reduced. However, copper exposure did not alter brain and muscle acetylcholinesterase (AChE) activity. Osmoregulatory function was also disturbed, in agreement with the above-mentioned changes noted in the gills, as detected by plasma osmolality reduction in the group exposed to 11μgCuL−1, and plasma chloride reduction at 2μgCuL−1. These concentrations also, coherently, lead to inhibition of branchial carbonic anhydrase activity. In the kidney, increased carbonic anhydrase activity was measured in the groups exposed to 2 and 7μgCuL−1. When these effects are compared to data available in the literature for other freshwater fish, also for 96h of exposure, R. quelen appears as a relatively sensitive species. In addition, the concentrations employed here were quite low in comparison to levels used for disease control in real culture practices (ranging from 4μgCuL−1 used against bacteria to 6000μgCuL−1 against fungal infections). We can conclude that the concentrations frequently employed in aquaculture are in fact not safe enough for this species. Such data are essential for the questioning and establishment of new policies to the sector.
► The susceptibility of the fish Rhamdia quelen to copper was evaluated/ R. quelen was shown to be a relatively sensitive species. ► Exposure to copper induces biochemical, morphological, and physiological effects. ► Concentrations frequently employed in aquaculture are in fact not safe enough.
The route of pathogen inoculation by needle has been shown to influence the outcome of infection. Employing needle inoculation of the obligately intracellular parasite Leishmania major, which is ...transmitted in nature following intradermal (i.d.) deposition of parasites by the bite of an infected sand fly, we identified differences in the preexisting and acute cellular responses in mice following i.d. inoculation of the ear, subcutaneous (s.c.) inoculation of the footpad, or inoculation of the peritoneal cavity (intraperitoneal i.p. inoculation). Initiation of infection at different sites was associated with different phagocytic populations. Neutrophils were the dominant infected cells following i.d., but not s.c. or i.p., inoculation. Inoculation of the ear dermis resulted in higher frequencies of total and infected neutrophils than inoculation of the footpad, and these higher frequencies were associated with a 10-fold increase in early parasite loads. Following inoculation of the ear in the absence of neutrophils, parasite phagocytosis by other cell types did not increase, and fewer parasites were able to establish infection. The frequency of infected neutrophils within the total infected CD11b(+) population was higher than the frequency of total neutrophils within the total CD11b(+) population, demonstrating that neutrophils are overrepresented as a proportion of infected cells. Employing i.d. inoculation to model sand fly transmission of parasites has significant consequences for infection outcome relative to that of s.c. or i.p. inoculation, including the phenotype of infected cells and the number of parasites that establish infection. Vector-borne infections initiated in the dermis likely involve adaptations to this unique microenvironment. Bypassing or altering this initial step has significant consequences for infection.
The Iguaçu River, located at the Southern part of Brazil, has a great socioeconomic and environmental importance due to its high endemic fish fauna and its potential to generate hydroelectric power. ...However, Iguaçu River suffers intense discharge of pollutants in the origin of the river. In a previous report, the local environmental agency described water quality to improve along the river course. However, no study with integrated evaluation of chemical analysis and biological responses has been reported so far for the Iguaçu River. In the current study, three different Brazilian fish species (
Astyanax bifasciatus
,
Chrenicicla iguassuensis
, and
Geophagus brasiliensis
) were captured in the five cascading reservoirs of Iguaçu River for a multi-biomarker study. Chemical analysis in water, sediment, and muscle indicated high levels of bioavailable metals in all reservoirs. Polycyclic aromatic hydrocarbons (PAHs) were detected in the bile of the three fish species. Integration of the data through a FA/PCA analysis demonstrated the poorest environmental quality of the reservoir farthest from river’s source, which is the opposite of what has been reported by the environmental agency. The presence of hazardous chemicals in the five reservoirs of Iguaçu River, their bioaccumulation in the muscle of fish, and the biological responses showed the impacts of human activities to this area and did not confirm a gradient of pollution between the five reservoirs, from the source toward Iguaçu River’s mouth. Therefore, diffuse source of pollutants present along the river course are increasing the risk of exposure to biota and human populations.
Inflammatory monocytes can be manipulated by environmental cues to perform multiple functions. To define the role of monocytes during primary or secondary infection with an intra-phagosomal pathogen ...we employed Leishmania major-red fluorescent protein (RFP) parasites and multi-color flow cytometry to define and enumerate infected and uninfected inflammatory cells in the skin. During primary infection, infected monocytes had altered maturation and were the initial mononuclear host cell for parasite replication. In contrast, at a distal site of secondary infection in mice with a healed but persistent primary infection, this same population rapidly produced inducible nitric oxide synthase (iNOS) in an IFN-γ dependent manner and was critical for parasite killing. Maturation to a dendritic cell-like phenotype was not required for monocyte iNOS-production, and enhanced monocyte recruitment correlated with IFN-γ dependent cxcl10 expression. In contrast, neutrophils appeared to be a safe haven for parasites in both primary and secondary sites. Thus, inflammatory monocytes play divergent roles during primary versus secondary infection with an intra-phagosomal pathogen.
Copper (Cu) is an essential metal utilized in aquaculture activities for both nutritional and disease control. Conversely, this metal can present a risk of exposure to biota depending on the used ...concentration, but data are still scarce and studies to establish the real risk of copper exposure to fish even in aquaculture activities are welcome. To evaluate a set of environmentally realistic doses of inorganic copper and so the potential risk of exposure to reproduction, Oreochromis niloticus were orally exposed to 0.1, 1.0 or 10.0 mg Cu.kg−1 body weight for 60 days (one dose each 10 days). Parameters regarding sperm quality, including viability, membrane integrity, mitochondrial functionality, apoptosis, lipid peroxidation, protein carbonylation, DNA integrity and motility were considered as signs of reproductive impairment. Additionally, as copper is also described as a pro-oxidant metal, we investigated the oxidative balance in liver (Non-protein reduced thiols concentrations-GSH, superoxide dismutase activity-SOD, lipid peroxidation-LPO, protein carbonylation-PCO and glutathione S-transferase-GST activity). Fishes exposed to copper showed poor sperm quality due to the observed reduced motility and motility period. Induced mitochondrial dysfunction, lipid peroxidation and apoptosis in germ cells, as well as DNA fragmentation confirms the high impairment of Cu to reproduction of O. niloticus exposed to copper in realistic doses. Exposure to the highest dose used in this experiment led to oxidative imbalance in liver, corroborating the deleterious effects of this metal to biological systems. These findings strongly suggest that even under very low Cu doses, or realistic doses as utilized in aquaculture activities, the metal may negatively affect O. niloticus reproduction, probably decreasing the success of aquaculture activities.
•Oreochromis niloticus exposed to copper showed poor sperm quality.•Doses of copper used in aquaculture can led to oxidative imbalance in fish liver.•Indiscriminate use in of copper in fish farming could impair fish reproduction.
The bioaccumulation of saxitoxins (STX) in the trophic chain, mainly in freshwater, are not completely known. This work aimed to elucidate the effects of STX on Hoplias malabaricus through trophic ...bioassay. The fish were fed once every five days with Astyanax sp. before being subjected to an intraperitoneal inoculation with the lysate of Cylindrospermopsis raciborskii culture containing 97% STX and 3% by neosaxitoxin and gonyautoxin during 20 days. The animal's liver was assessed using biomarkers as activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPx), and concentrations of reduced glutathione (GSH) and lipoperoxidation (LPO) and protein carbonylation (PCO). In the blood was analyzed the genotoxic and hematological parameters. The hepatosomatic index and the relative condition factor did not show a significant difference between the exposed and control groups. The values of mean corpuscular hemoglobin concentration and mean corpuscular hemoglobin increased in the STX group. The hepatic tissue from both groups exhibited a typical pattern that have been already described for most teleost fish. The results suggested the generation of reactive oxygen species, with increased activity of GPx and concentrations of LPO and GSH; whereas the specific activity of SOD decreased. However, no changes were observed in the CAT, PCO, and DNA damage. Although the STX effects are known as neurotoxic, this cyanotoxin caused liver biochemical alterations that can be considered ecologically relevant.
► Fish exposed to saxitoxin (STX) on Hoplias malabaricus through trophic bioassay. ► Mean corpuscular hemoglobin concentration and mean corpuscular hemoglobin increased in the STX group. ► The hepatic tissue from both groups exhibited a typical pattern that have been already described for most teleost fish. ► The results suggested the generation of reactive oxygen species. ► STX caused liver biochemical alterations that can be considered ecologically relevant.
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