Effect Of Polystyrene Microplastics On The Antioxidant System And Immune Response Of Gift(Oreochromis Niloticus)

The rising amount and accumulation of plastics in the environment have of recent become a major concern and a worldwide environmental menace.Plastics are broadly used in many disciplines due to their remarkable and irreplaceable qualities.Regardless of the source of entry,plastics ultimately degrade into microplastics by mechanical,chemical or biological mechanisms.Recent investigations have reported large number of microplastics in the freshwater environment,which may have adverse effects on growth and development of freshwater organisms.Polystyrene(PS)has been confirmed by pooled prevalence data to be one of the most abundant plastic type found in freshwater environments.Hence,identifying the potential effect of polystyrene microplastics(PS-MPs)on the health of freshwater organisms is a necessity.The present study was conducted to investigate the effects of chronic sub-lethal dose of PS-MPs on the oxidative status and immune response of the genetically improved farmed tilapia(GIFT).To carry out this study,Juveniles of tilapia(5.1±0.2 g)were exposed to concentrations of 0,75 nm,7.5 μm,750μm,75 nm+7.5 μm+750 μm and 75 nm+Chlorella for 14 days.The oxidative status including reactive oxygen species(ROS),superoxide dismutase(SOD)and immune response interleukin1?(IL-1?)and tumor necrosis factor-α(TNF-α)were measured at 7,10 and 14 days of exposure.At the end of the exposure period,compared to the control,significant(P<0.05)changes in ROS activities were observed with an elevation in the liver across all the concentrations.ROS content in the brain and gills were significantly decreased at treatment group 75 nm+chlorella and significantly increased at group 750 μm after the 14 d exposure to PS-MPs.SOD activities in the intestine showed an elevation at 75 nm+chlorella and in the brain and gills at 750 μm.During the14 days exposure of PS-MPs at groups 75 nm and 75 nm+chlorella,SOD activities in the gills generally decreased over time.The highest ROS and SOD levels were observed in the brain at750μm with the lowest in the intestines at the same concentration.The activity of IL-1? was significantly up-regulated in the liver in response to PS-MPs across all the exposure groups.IL-1? was significantly up-regulated in the brain at concentration 75 nm and in the gills at 750 μm.TNF-α was significantly up-regulated in the brain at 75 nm,750 μm and 75 nm+7.5 μm+750 μm,in the liver at 75 nm,7.5 μm and 750 μm,in the intestine at 75 nm and in the gills at 750 μm.The highest IL-1? and TNF-α activities were recorded in the brain and the lowest in the intestine at concentration 750 μm.Overall,the current study revealed that GIFT’s immune response and antioxidant system could be affected by PS-MPs.