Transcriptome analysis reveals differential gene expression in Lateolabrax maculatus following waterborne Zn exposure

Abstract

The spotted sea bass, Lateolabrax maculatus, is an economically important farmed fish species in the world. To gain a better understanding of the immune response, antioxidant enzymes and stress (heat shock protein 70, HSP70) in L. japonicas, we analyzed its transcriptome following waterborne Zn exposure (35 mg/L Zn) at 24 h in the liver. Following assembly and annotation, 104,787 unigenes with an average length of 2230 bp were identified. A total of 2882 differentially expressed genes (DEGs) in the L. japonicas were observed at 24 h post waterborne zinc treatment, including 1289 up-regulated genes and 1593 down-regulated genes. Clusters of Orthologous Groups of proteins (KOG/COG) annotation demonstrated that a total of 32,866 unigenes classified into 26 categories. Gene ontology (GO) analysis revealed 20 biological process subcategories, 4 cellular component sub-categories and 17 molecular function subcategories. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis identified immune, antioxidant and stress pathways. Quantitative reverse transcription polymerase chain reaction measured the expression of 10 genes involved in the immune, antioxidant and stress. HSP70 was significantly up-regulated, whereas g-type lysozyme (LYZ-G), CU/ZN superoxide dismutase (CU/ZN-SOD), glutathione peroxidase 7 (GPX7), glutathione reductase (GR), glutathione-S-transferase (GST), nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein-1 (Keap1) were significantly down-regulated. This study enriches the L. japonicas transcriptome database and provides insight into the immune response, antioxidants and stress of L. japonicas against heavy metal pollution.