Histological Assessment and Transcriptome Analysis Provide Insights into the Toxic Effects of Perfluorooctanoic Acid to Juvenile Half Smooth Tongue Sole Cynoglossus semilaevis

Perfluorooctanoic acid(PFOA)is a widespread synthetic persistent organic pollutant that may enrich along the food chain and affect the growth,development,reproduction,and lipid metabolism of aquatic organisms,particularly the benthic organisms.How-ever,the toxic effects of PFOA on the half-smooth tongue sole Cynoglossus semilaevis,a commercial benthic fish in China,have rarely been reported.Because juvenile fish are sensitive to environmental pollutants,in the present study,histological assessment and tran-scriptome sequencing were performed to determine the short-term impact of PFOA on juvenile half-smooth tongue soles.Histologi-cal analysis showed that PFOA exposure caused hepatocyte rupture,intestinal villi breakage,increased goblet cell count,and brain ab-normal.Transcriptome results showed that some interesting signaling pathways,such as glycolysis/gluconeogenesis,PPAR signaling pathway and GABAergic synapse signaling pathway,were enriched after PFOA exposure.In addition,some metabolic,immune and neural genes were differentially expressed,which including ependymin,hbb1-like and gad 1,and they were up-regulated after 14 days of exposure.Transcriptome results also indicated that half-smooth tongue sole might improve energy metabolism in response to PFOA toxicity after 7 days of exposure.These findings provide a basis for studying the ecological effects of PFOA on marine benthic fishes.