Hepatotoxic effects of exposure to different concentrations of Dibutyl phthalate (DBP) in Schizothorax prenanti: Insights from a multi-omics analysis

Dibutyl phthalate (DBP) is one of the most widely used phthalate esters (PAEs) that raise increasing ecotoxicological concerns due to their harmful effects on living organisms and ecosystems. Recently, while PAEs pollution in the Yangtze River has attracted significant attention, little research has been conducted on the impact of PAEs stress on S. prenanti, an endemic and valuable species in the Yangtze River. In this study, one control group (C-L) and three experimental groups: T1-L (3 µg/L), T2-L (30 µg/L), and T3-L (300 µg/L) were established with reference to the DBP concentration in the environment. For the first time, we investigated the effects of DBP stress on the liver of S. prenanti using histomorphological, physiological, and biochemical indexes, as well as a joint multi-omics analysis. The results revealed that compared to the C-L group, liver structural damage and stress were not significant in the environmental concentration group (T1-L) and the number of differential genes and differential metabolites were lower. However, as DBP stress concentration increased, the liver damage became severe, with significant vacuolation and hemolysis observed in the T2-L and T3-L groups. The TUNEL assay revealed a significant increase in the number of apoptotic cells along with a notable rise in differential genes and metabolites in the T2-L and T3-L groups. Oxidative stress markers (T-AOC, SOD, CAT, and GSH-PX) were also significantly higher in the T2-L and T3-L groups. RNA-Seq analysis showed that the protein processing in the endoplasmic reticulum pathway was most significantly -enriched differential gene pathway shared by both C-L vs T2-L and C-L vs T3-L, with most of the genes in this pathway showing significant up-regulation. This suggests that the protein processing in the endoplasmic reticulum pathway may play a key role in protecting the liver from injuries caused by high DBP stress. Interestingly, C XI, C XII, C XIII, C XIV and C XV in the chemical carcinogenesis - reactive oxygen species pathway were significantly down-regulated in the T2-L and T3-L groups based on combined transcriptomic and metabolomic analyses, suggesting that DBP causes liver injury by disrupting mitochondria. This comprehensive histomorphometric and multi-omics study demonstrated that the current DBP concentration in the habitat of S. prenanti in the upper reaches of the Yangtze River temporarily causes less liver damage. However, with increasing of DBP concentration, DBP could still cause serious liver damage to S. prenanti. This study provides a new mechanistic understanding of the liver response mechanism of S. prenanti under different concentrations of DBP stress and offers basic data for the ecological protection of the Yangtze River.