Cadmium affects the mitochondrial viability and the acid soluble thiols concentration in liver, kidney, heart and gills of Ancistrus brevifilis (Eigenmann, 1920).

The freshwater fish Ancistrus brevifilis, which is found in Venezuelan rivers, is considered a potential sentinel fish in ecotoxicological studies. The cadmium (Cd) effect on the mitochondrial viability (MV) and acid soluble thiols levels (AST) in A. brevifilis tissues (liver, kidney, heart, and gill) was evaluated. Forty-two fish with similar sizes and weights were randomly selected, of which 7 fish (with their respective replicate) were exposed for 7 and 30 days to a Cd sublethal concentration (0.1 mg.l(-1)). We determined the MV through a Janus Green B colorimetric assay and we obtained the concentration of AST by Ellman's method. Mitochondrial viability decreased in fish exposed to Cd for 30 days with the liver being the most affected tissue. We also detected a significant decrease in AST levels was in fishes exposed to Cd for 7 days in liver and kidney tissues; these results suggests that AST levels are elevated in some tissues may act as cytoprotective and adaptive alternative mechanism related to the ROS detoxification, maintenance redox status and mitochondrial viability. Organ-specifics variations were observed in both assays. We conclude that the Cd exposure effect on AST levels and MV, vary across fish tissues and is related to the exposure duration, the molecule dynamics in different tissues, the organism and environmental conditions.

Histopathological changes in the head kidney induced by cadmium in a neotropical fish Colossoma macropomum.

We evaluated the effect of cadmium (Cd) on the structure and function of the head kidney in the freshwater fish Colossoma macropomum (C. macropomum). Juveniles were exposed to 0.1 mg/L CdCl2 for 31 days. Blood samples were examined using hematological tests and head kidney histology was determined by light microscopy. The concentration of Cd in the head and trunk kidneys was measured using an atomic absorption spectrophotometer. Cd produced histopathological changes in the head kidney, the most evident of these being: the thickening of the vein wall, an increase in the number of basophils/mast cells close to blood vessels and a severe depletion of hematopoietic precursors especially the granulopoietic series. In the blood, a decrease in the total leucocytes and hemoglobin concentration was observed. Cd-exposed fish showed higher Cd concentrations in the trunk kidney than the head kidney. In conclusion, exposure to Cd affected precursor hematopoietic cells in C. macropomum.

Efecto del cobre y del cadmio sobre la respuesta inmune innata del pez Colossoma macropomum / Copper and cadmium effects on the innate immune response of the fish Colossoma macropomum

En este trabajo se evaluó la respuesta inmunológica celular inespecífica del pez Colossoma macropomum (Cuvier, 1818) expuestoaconcentracionessubletalesde cobreycadmio,atravésde la determinación de la viabilidad celular, la quimiotaxis, la fagocitosis y la muerte bacteriana en células inmunocompetentes extraídasdelriñóncefálico,lasangreyel hígado.Lospecesfueron expuestos por separado a 0,5 mg/L de cloruro de cobre y 1,0 mg/L de cloruro de cadmio durante 28 días; después de la exposición, se depuraron por el mismo período. La viabilidad celular se mantuvo entre 99-94%. La exposición al cadmio causó una reducción significativa en la respuesta quimiotáctica de granulocitos en los tejidos evaluados. Tanto los peces expuestos a cobre como los expuestos a cadmio presentaron una disminución significativa en la respuesta fagocítica de granulocitos. En sangre, el cadmio afectó la efectividad de los granulocitos de inducir muerte bacteriana; el cobre sin embargo, afectó la efectividad de inducir muerte bacteriana en los granulocitos provenientes del hígado. Los peces expuestos a cadmio presentaron un incremento significativo en los niveles de cortisol sérico y una disminución de esta hormona en los peces expuestos a cobre. Estos resultados demuestran que la exposición crónica a los metales cobre y cadmio produce una inhibición de la respuesta inmune inespecífica en el pez Colossoma macropomum (AU)

The non-specific immune response was evaluated thought cellular viability, quimiotaxis, phagocytosis and bacterial killing by PMN of innate immune cells providing of blood, head kidney and liver of freshwater fish Colossoma macropomum. Fish were exposed to 0.5 mg/L copper chloride and 1.0 mg/L cadmium chloride for 28 days; finalized the exposure, the fishes were depurated for 28 days. The cellular viability was between 94-99%, being observed the lowest values in both Cd-exposed and Cu-exposed fishes. A decrease in quimiotatic responses was found in granulocytes of the evaluated tissues. We observed a decrease in phagocytic response in both copper exposed fish and cadmium exposed fish on the three evaluated tissues. Cadmium reduced the effectiveness to induce bacterial killing in blood granulocytes; however, copper reduced the response in granulocytes of the hepatic tissue. The serum cortisol level was increased in Cd-exposed fish: on the contrary, it was decreased in Cu-exposed fish. These results suggest that chronic exposure to cadmium and copper of the fish Colossoma macropomum decreased the innate immunological response (AU)

Immune and biochemical responses of the polychaete Eurythoe complanata exposed to sublethal concentration of copper.

A series of immunoassays, enzyme activity tests and growth rate analyses were conducted on the free living polychaete Eurythoe complanata after 21 day exposure to 0.2 mg.L-1 sublethal nominal concentration of Cu2+ (CuSO45H2O). The immunological assessment was further made immediately after 15 and 30 day post-exposure. Immune cytological parameters, coelomocyte viability and differential coelomocyte counts showed significant differences between exposed an non-exposed worms. Coelomocyte responses to antigenic mouse red blood cells (MRBC), such as formation of secretory (SR) and erythrocyte rosettes (ER), and phagocytosis evidenced significant impairments in the immunological defenses related to copper contamination, related to a two fold increase in Cu-carcass tissue concentration (13.70 +/- 1.50 micrograms.g-1 dry wt, n = 6). The normal immune functions were reestablished upon depuration as tissue Cu content approached basal levels (7.40 +/- 1.70 micrograms.g-1 dry wt, n = 6). Neither enzyme activity of coelomic transaminases as indicators of tissue damage, nor growth rate indexes (carcass tissue RNA/DNA and protein/DNA ratios) were affected by copper exposure. In conclusion, the immunoassays yielded highly sensitive results compared to biochemical markers, suggesting the potential usefulness of immune parameters as environmental stress indicators for sediment/aquatic bioassays with the polychaete Eurythoe complanata.