The combined effect of titanium dioxide (TiO2) nanoparticles and nickel on the gill tissue of zebrafish (Danio rerio)

The purpose of this study was to determine the effect of nickel (Ni) doped TiO2 NPs on gill histopathology of zebrafish (Danio rerio). In this study, a total number of 200 zebrafish (Danio rerio) with average weight of 3g and length body of 4cm were used. In this study, four non-lethal concentrations of Ni doped TiO2 NPs were used that included 1, 10, 30, 100 mg/L; also control group was considered. The results showed that the Ni doped TiO2 NPs on gill tissue cause some impacts such as secondary bending blades, blades secondary hypertrophy, increased mucus secretion, fusion in the secondary lamellae, hyperplasia and eventually necrosis increases. Although histological changes in gill tissue were observed in all groups, but the severity of these changes increased with increasing concentration of Ni doped TiO2 NPs. Moreover, changes were significant between exposure group and control group in parameters of diameter of gill filaments, diameter of secondary lamellae, and length of secondary lamellae (P