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

Organisms are continuously exposed to a plethora of anthropogenic toxicants daily released to the environment. In the present study, the effects of a mixture of halogenated organic compounds (HOCs) extracted from hepatic lipids were evaluated on the primary hepatocyte culture from fish Hoplias malabaricus. Cells were isolated through non-enzymatic perfusion protocol and cultured during 3 days to allow attachment. Two concentrations of the mixture of HOCs (10 ng ml(-1) [Mix10] and 50 ng ml(-1) [Mix50]) were tested in cells for 2 days by medium replacement. The control groups, with and without solvent (DMSO) were run in the same conditions. Both tested concentrations of HOCs increased the catalase and GST activities, but only the Mix50 increase the DNA damage and decreased the GSH concentration and cell viability. Lipid peroxidation increased in the Mix10 group, but it seems to be more a consequence of DMSO presence than the HOCs themselves. The DMSO at 0.1% increased the lipid peroxidation, GSH concentration, apoptosis and DNA damage. The present data suggest that DMSO interferes with the hepatocytes of H. malabaricus in culture and that the mixture of HOCs tested alters the redox state of the hepatocytes.

Hematological findings in neotropical fish Hoplias malabaricus exposed to subchronic and dietary doses of methylmercury, inorganic lead, and tributyltin chloride.

Hematological indices are gaining general acceptance as valuable tools in monitoring various aspects the health of fish exposed to contaminants. In this work some effects of methyl mercury (MeHg), inorganic lead (Pb2+), and tributyltin (TBT) in a tropical fish species were evaluated by hematological methods after a trophic exposition at a subchronic level. Forty-two mature individuals of the freshwater top predator fish Hoplias malabaricus were exposed to trophic doses (each 5 days) of MeHg (0.075 microg g(-1)), Pb2+ (21 microg g(-1)), and TBT (0.3 microg g(-1)) using young fish Astyanax sp. as prey vehicle. After 14 successive doses over 70 days, blood was sampled from exposed and control groups to evaluate hematological effects of metals on erythrocytes, total leukocytes and differential leukocytes counts, hematocrit, hemoglobin concentration, and red blood cell indices mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Transmission electron microscopy and image analysis of erythrocytes were also used to investigate some morphometric parameters. Results show no significant effects in MCH and MCHC for all tested metals, but differences were found in erythrocytes, hemoglobin, hematocrit, MCV, and white blood cells counts. The number of leukocytes was increased in the presence of MeHg, suggesting effects on the immune system. Also the MCV increased in individuals exposed to MeHg. No ultrastructural damages were observed in red blood cells but the image analysis using light microscopy revealed differences in area, elongation, and roundness of erythrocytes from individuals exposed to Pb2+ and TBT but not in the group exposed to MeHg. The present work shows that changes in hematological and blood indices could highlight some barely detectable metal effects in fish after laboratory exposure to contaminated food, but their application in field biomonitoring using H. malabaricus will need more detailed studies and a careful consideration of environmental parameters.

Effects of dietary Pb(II) and tributyltin on neotropical fish, Hoplias malabaricus: histopathological and biochemical findings.

Trahira (Hoplias malabaricus) used to investigate the effects of successive Pb(II) or tributyltin (TBT) dietary doses. After 70 days of acclimation, individuals were exposed to 21 microg Pbg(-1) or 0.3 microg TBTg(-1) (5-day intervals, 14 doses). Two experiments were conducted to investigate the histopathological effects (liver and kidney) and measure the cholinesterase activity (muscle and brain) after Pb(II) or TBT dietary doses. A number of morphological effects were observed in liver, including cytoskeleton disturbance, microautophagy of mitochondria, nuclear damage, and cell death. In kidney, necrosis area, increasing of the neutrophils cell number, changes in melano-macrophage centers, and free macrophages were frequently registered after both Pb(II) and TBT exposures. The cholinesterase activity was inhibited in muscle after 14 doses of Pb(II), but no effects were found in individuals exposed to TBT. In summary, this work is the first to report detailed in vivo toxic effects in tropical fish, H. malabaricus, after dietary sublethal exposure to Pb(II) and TBT.