Effects of colloids with different compositions on benzophenone-3 biotoxicity in zebrafish embryos

The fate of the pollutants in aquatic environment is closely related to colloids, and the carrier effect of colloids on pollutants not only affects their bioaccumulation, but may also affect their toxicity. In this study, the effects of natural colloid with different components on the biological toxicity of benzophenone-3 (BP3) to zebrafish larvae (Diano rerio) were studied. BP3 caused oxidative stress damage, thyroid system disorders and neurotoxicity in zebrafish larvae. And in the co-exposure groups, the organic and black carbon mineral (BCM) colloids enhanced the organism's antioxidant system by regulating the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), reducing the lipid peroxidation damage in larvae. BCM colloids caused the thyroid system disorders in organisms, while organic colloids exacerbated the thyroid toxicity by transporting more BP3 into organisms, inducing severe abnormal heartbeats. The BCM and organic colloids regulated the acetylcholinesterase (AChE) activity and/or 5-hydroxytryptamine (5-ht) contents by affecting the neuroactive ligand receptor interaction pathway in zebrafish larvae, significantly increasing their swimming speed in co-exposure groups under the light condition. In addition, the effects of colloid-bound and freely dissolved BP3 absorbed by organisms on their physiological and biochemical activities were different. By analyzing the relative expression of the significant differential metabolites affected by BP3 in all experimental groups, it was found that colloid-bound and freely dissolved BP3 had a synergistic effect on most of these metabolites and pathways. However, the freely dissolved BP3 interfered with the purine metabolic pathway by mediating 2-(amidino)-n1-(5-phospho-d-ribosyl)acetamidine, and the tyrosine metabolic pathway by mediating choline and uranylacetic acid, while the colloid-bound BP3 has no or inverse regulatory effects on these three metabolites. This study provided a new perspective for the biotoxicity study of the pollutants in aquatic environment, necessitating a reconsideration of the real ecological risks of emerging pollutants in the presence of natural colloids.