Copper and nickel uptake and accumulation, and their effects on redox and electrical potentials of hepatopancreatic cells of Oniscus asellus Linnaeus (Porcellionidae, Isopoda)

Abstract

Highest tissue Cu concentrations (1728 μg∙g dry weight⁻¹) in whole Oniscus asellus, reared for 7 days on carrot powder containing 50 μg Cu∙g dry weight⁻¹, 10 μg Ni∙g dry weight⁻¹, or a mixture of 50 μg Cu and 10 μg Ni∙g dry weight⁻¹, were observed in isopods on 50 μg Cu∙g dry weight⁻¹, and lowest (917 μg∙g dry weight⁻¹) in those on 10 μg Ni∙g dry weight⁻¹. Highest Ni concentrations (277 and 272 μg∙g dry weight⁻¹) were present in isopods fed on a mixture of 50 μg Cu and 10 μg Ni∙g dry weight⁻¹ and 10 μg Ni∙g dry weight⁻¹, respectively, and lowest (201 μg∙g dry weight⁻¹) in those on 50 μg Cu∙g dry weight⁻¹. Of the total body-tissue Cu, 8–66% was contained in membrane-bound vesicles of hepatopancreatic S-cells, and 73–89% of Ni was present inside the lumen and within S-cells of the hepatopancreas. The presence of Ni in the diet appeared to adversely affect the absorption and hepatopancreatic storage of Cu. Copper slightly enhanced, and nickel drastically reduced, the hepatopancreatic redox (= catalytic activity) and cell-membrane surface potentials. The significance of these findings is discussed.