Effect of Diflubenzuron Exposure on Gene Expression in Cyprinus carpio Liver Based on Transcriptomics

Abstract

As a benzoylurea insecticide, diflubenzuron (DFB) has been widely used in the prevention and control of diseases and insect pests in vegetables, fruits, grain cultivation, and other fields in recent years. In addition, because of its low acute toxicity, excellent biological activity, and specific action mechanism, DFB has been widely used in aquaculture to kill bacteria and lice. With its large-scale production and widespread use, its partial residue remains in environmental media, such as water, soil, and the atmosphere, and causes direct or indirect chronic toxicity to aquatic organisms. The residual DFB enters the human body along the food chain and poses a threat to human health when it reaches a certain concentration through chronic exposure and long-term accumulation. At present, research on DFB insecticides has been limited to the usage and dosage, residual metabolism, and its toxicological effects on the environment. There have been no reports, to our knowledge, on the effect of DFB on gene expression in carp liver in China. The purpose of this study was to explore the differential expression of genes in carp liver under DFB stress.In this study, carp (Cyprinus carpio) was selected as the research subject, and three exposure experiments for 15 days under 0.1 and 1.0 mg/L medicated bath concentrations were carried out in parallel for each concentration. High-throughput sequencing of the liver was performed using the Illumina NovaSeq 6000. Differentially expressed genes (DEGs) were screened by Padj < 0.05 and |log2FoldChange| ≥1, and bioinformatics analysis, such as Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, were performed. The transcriptome analysis results showed that 2 406 and 2 688 DEGs changed significantly at 0.1 and 1.0 mg/L exposure concentrations, respectively, and 821 DEGs were co-expressed between the two groups. GO analysis results showed that DEGs in the DFB exposure group were enriched in biological processes, cell compositions, and molecular functions. KEGG enrichment analysis showed that DEGs in the low DFB concentration exposure group were significantly enriched in metabolic pathways, such as biodegradation and metabolism of xenobiotics, lipid metabolism, carbohydrate metabolism, amino acid metabolism, signal molecules and interactions, endocrine system, and immune system. In addition to the above metabolic pathways, DEGs in the high DFB concentration exposure group were significantly enriched in metabolic pathways, such as folding, classification and degradation, transport, and catabolism.Studies have shown that DFB exposure causes the biodegradation and metabolism of xenobiotics, lipid metabolism, carbohydrate metabolism, and amino acid metabolism, and generates endoplasmic reticulum stress, inflammatory response, and immune toxicity. In summary, the results of this study provide basic data and a theoretical basis for further research on the molecular mechanism of DFB stress in carp.

Keywords

• carp cyprinus carpio
• diflubenzuron
• liver
• transcriptomics
• toxicology