Effects of titanium dioxide (TiO2)/activated carbon (AC) nanoparticle on the growth and immunity of the giant freshwater prawn, Macrobrachium rosenbergii: potential toxicological risks to the aquatic crustaceans.

Abstract

Due to their unique physicochemical characteristics, nanomaterials exhibit many excellent properties and functions, leading to their applications in numerous fields. The large-scale production and widespread application of nanomaterials have inevitably resulted in their release into the environment, especially the water environment. Several studies have confirmed that exposure to nanomaterials can be toxic to aquatic organisms. However, few studies have focused on the effects of nanomaterial exposure on growth and immunity in crustaceans. In the present study, juvenile Macrobrachium rosenbergii were exposed to different concentrations of titanium dioxide (TiO2)/activated carbon (AC) composite nanomaterial (0.1 and 0.5mg/L) for 45days. The effects of nanoparticle exposure on digestion and antioxidant-related enzyme activities, as well as the expression of growth and immunity-related genes and signaling pathway, were evaluated. Our results show that in response to low concentration of TiO2/AC nanoparticle (0.1mg/L), most of the enzyme activities related to digestion and antioxidation (TPS, LPS, AMS, SOD, and CAT) were diminished. On the contrary, the GSH-Px activity increased under the 0.1mg/L group of TiO2/AC nanoparticle concentration. Additionally, the level of digestive and antioxidant enzyme activities we detected was increased when exposed to 0.5mg/L TiO2/AC nanoparticle. By comparison to the expression level of growth-related genes in the control group, MSTN, CaBP, E75, Raptor, EcR, and EGF were significantly inhibited at 0.1 and 0.5mg/L concentrations of TiO2/AC nanoparticle, whereas the expression level of genes (TLR, JAK, STAT, PPAF, ACP, and AKP) related to immunity was increased when exposed to different concentrations of TiO2/AC nanoparticle. Compared with the control group (0mg/L concentration), 5166 DEGs were identified in the TiO2/AC nanoparticle group, and a large number of DEGs were involved in molting, energy metabolism, stress tolerance, and germ cell development. Moreover, KEGG analysis revealed that many DEGs were assigned into signaling pathways related to metabolic growth and immune stress. These results showed that exposure to TiO2/AC nanoparticle will result in the changes of enzyme activity and routine mRNA expression, suggesting that TiO2/AC nanoparticle which existed in aquatic environment might affect the physiology of M. rosenbergii. This study will provide significant information for the evaluation of nanomaterial toxicity on aquatic crustaceans.