| Triphenyltin(TPT)is widely used due to its excellent general properties,and its pollution in the water environment has caused strong ecological effects.Due to the existence of various pollutants in the water environment,it is necessary to assess the combined toxicity risk of TPT and co-existing pollutants,especially about TPT and new pollutants.As a representative of new pollutants,antibiotics have caused serious ecological risks due to their widespread abuse.This research focuses on widely used quinolone antibiotics.In addition,the environmental problems caused by another typical new pollutant,microplastics,are also very serious.At present,there are few studies on the combined exposure of TPT and antibiotics or microplastics,but TPT has a high coexistence risk with the two new pollutants in the real environment.Therefore,this research investigated the toxic effects of combined exposure of TPT and the quinolone antibiotic Norfloxacin(NOR)or polystyrene microplastic(MP)on juvenile carp,aiming to provide information for the combined toxicity of TPT and provide a scientific basis for the treatment of water environmental pollutants.In this study,a 42-day exposure experiment was conducted on carp juveniles based on the environmental concentration levels of the three risk sources of TPT,NOR,and MP in heavily polluted areas.After 42 days,6 fish were randomly selected for anesthesia and sampling,and carp brain tissue,intestinal contents and intestinal tract were collected.Through multi-omics sequencing technology analysis,physiological,biochemical and molecular level detection,combined with the microbe-host relationship,the single/combined toxic effects of three risk sources on carp nerve,immunity and metabolism were explored from the perspective of "gut-brain axis".The result shows:(1)Through the research of the toxic effect on brain tissue,it was found that TPT had a significant effect on the digestion and absorption of fat in a single exposure;NOR induced lipid metabolism disorder,affecting the metabolism of cytochrome P450 to xenobiotics;MP can induce immunity inhibition occurs.In the combined exposure,when TPT NOR was exposed for a long time,the participation of TPT amplified the monotoxicity of NOR on lipid metabolism and immunosuppression in carp,damaged the immune function of carp through lipid peroxidation,and induced a significant increase in neurobiochemical indexes;for TPT_MP,the involvement of TPT amplified MP-mediated immunosuppressive effects,and TPT_MP had no significant effect on nerves.(2)In the carp intestinal barrier,it was found that the mucous glycoprotein secreted by the intestines and the intestinal immune parameters in the TPT_NOR and the TPT MP group significantly increased,which changed the structure of the intestinal flora.The participation of TPT amplified the disorder of glucose and lipid metabolism caused by NOR,and the long-term inflammation causes damage to the intestinal tract and inhibits intestinal immune-related genes to varying degrees.Moreover,the involvement of TPT also amplified the immunosuppression caused by MP.The combined toxic effects of the two combined exposure groups on lipid metabolism and digestive enzyme activities were greater than the toxicity of single substances.(3)From the perspective of the "gut-brain axis",it was found that in the lipid metabolism of carp brain tissue,the abundance of the bacteria Firmicutes that induces intestinal lipid accumulation was dominant in the TPT_NOR group,and the levels of genes involved in lipid metabolism and accumulation in the brain were increased.In addition,immune-related differential genes were significantly related to the dominant microbes in the gut microbiota. |
