Toxic effects of cobalt parahydroxybenzoate on tissue histopathology and serum proteins in Capoeta capoeta capoeta

Cobalt, which is commonly used in many fields, may present an environmental risk. In this study, effects of cobalt parahydroxybenzoate (CoPHB), a less known form of cobalt, on tissue histopathology and serum proteins of Capoeta capoeta capoeta were investigated. Fish obtained from Kars River, Turkey were placed for 10 days in 500 L-containers in which CoPHB was added at 1 or 2 mg/L of final concentrations. At the end of the treatment period, fish were dissected; all the organs were collected and processed routinely for histological examination. Degeneration in he-patocytes and dissociation in hepatic cords were observed in the treatment groups. The severity of the findings increased, and necrosis was noted in the liver of fish exposed to higher concentration of CoPHB. In gill, degeneration and occasional necrosis in the epithelial cells of secondary lamellae were determined in both groups. Degeneration and necrosis of villous epithelium in the intestine were observed only in fish exposed to higher concentration of CoPHB. In electrophoretic analysis, serum samples collected from fish were run in sodium dodecyl sulphate ployacrylamide gel electrophoresis (SDS-PAGE). Compared to control, over-expression and inhibition of proteins with 85.8, 82.6, 73.9, 68.5 kilodalton (kD) and 23.0 and 15.2 kD molecular weights were detected in the fish exposed to CoPHB, respectively. Increases and decreases in the expression of these proteins were also found to be dose-depended. Overall, the results of this study suggest that CoPHB causes prominent degeneration in several organs, and alters the serum protein levels in fish, and therefore might be dangerous to life.