The effects of exposure to microplastics on grass carp (Ctenopharyngodon idella) at the physiological, biochemical, and transcriptomic levels

Microplastics (MPs) are pollutants that are widely distributed in the aquatic environment. Fish are directly exposed to water and are at risk of ingesting a large amount of MPs. In the present study, the grass carp were exposed to two concentrations of MPs (1000 and 100 mu g/L) and fluorescence signals were detected in the liver digestion solution. Grass carp exposed to MPs for 21-days showed liver cytoplasmic vacuolation and inhibited growth. At the end of the exposure period, the fish treated with MPs exhibited inhibition of the antioxidant system and enhancement oxidative stress in comparison with the control group. The transcriptome analysis of grass carp was then performed to reveal the molecular mechanism of the response to MPs. In total, 1554 differentially expressed genes (DEGs) were identified. The results of GO and KEGG pathway analysis of the DEGs identified energy metabolism-related pathways and peroxisome proliferator-activated receptor (PPAR) signaling pathway. Taken together, the present study not only highlighted oxidative stress and metabolism disorders related to MP ingestion, but also determined the risk of MP exposure to teleost.