Abstract
Enrofloxacin is an important antimicrobial drug that is widely used in aquaculture. Enrofloxacin residues can have negative effects on aquatic environments and animals. The toxicological effects of different concentrations of enrofloxacin residues in cultured water on Chinese mitten crabs (Eriocheir sinensis) were compared. A histological analysis of the E. sinensis hepatopancreas demonstrated that the hepatopancreas was damaged by the different enrofloxacin residue concentrations. The hepatopancreas transcriptome results revealed that 1245 genes were upregulated and that 1298 genes were downregulated in the low-concentration enrofloxacin residue group. In the high-concentration enrofloxacin residue group, 380 genes were upregulated, and 529 genes were downregulated. The enrofloxacin residues led to differentially expressed genes related to the immune system and metabolic processes in the hepatopancreas of the Chinese mitten crab, such as the genes for alkaline phosphatase, NF-kappa B inhibitor alpha, alpha-amylase, and beta-galactosidase-like. The gene ontology terms "biological process" and "molecular function" were enriched in the carboxylic acid metabolic process, DNA replication, the synthesis of RNA primers, the transmembrane transporter activity, the hydrolase activity, and the oxidoreductase activity. A Kyoto Encyclopedia of Genes and Genomes pathway analysis determined that the immune and metabolic signal transduction pathways were significantly enriched. Furthermore, the nonspecific immune enzyme (alkaline phosphatase) and the metabolic enzyme system played a role in the enrofloxacin metabolism in the E. sinensis hepatopancreas. These findings helped us to further understand the basis of the toxicological effects of enrofloxacin residues on river crabs and provided valuable information for the better utilization of enrofloxacin in aquatic water environments.