Investigation on the osmoregulation system of fish (Oreochromis niloticus) exposed to titanium and aluminum nanoparticles in water with increased salinity

The osmoregulation system of freshwater fish is very sensitive to salinity increase in water. There is not enough data on the accumulation of nanoparticles in tissues of the Nile tilapia O. niloticus exposed to nanoparticles in increased salinities, and the responses of ion ATPases (Na,K-ATPase, Mg-ATPase, Ca-ATPase) belonging to the osmoregulation system. In this study, the accumulation of aluminium and titanium in muscle and gill tissues and, also the responses of ATPases in the gill were investigated following exposures to different concentrations (1 and 10 mg/L) of Al2O3 and TiO2 nanoparticles in acute (2 days) and chronic (30 days) durations. The data showed that although nanoparticles accumulated in all tissues at both salinities (p<0.05), the highest accumulation occurred in gill tissues. Although the increase in salinity increased the accumulation of nanoparticles in acute duration, it decreased in chronic duration (p<0.05). Although there was no significant alteration (p>0.05) in the activity of ATPases in the intestine, there were significant changes (p<0.05) in ATPase activities in the gill. There were significant (p<0.05) decreases in gill ATPase activities of control fish at high salinity. Similarly, salt+nanoparticle exposures caused significant decreases in gill ATPase activities compared to salt control. Similarly, significant decreases in gill ATPase activities were observed in salt+nanoparticle exposure compared to nanoparticle exposure alone. Keywords: Freshwater fish, Nanoparticle, Salinity, ATPase, Osmoregulation