Transcriptome analysis of oriental river Prawn(Macrobrachium nipponense)Hepatopancreas in response to ammonia exposure.

The oriental river prawn, Macrobrachium nipponense, is an economically and nutritionally important species of the Palaemonidae family of decapod crustaceans. Ammonia is a major aquatic environmental pollutant that negatively affects the health of prawns and their associated commercial productivity. Here, we used high-throughput sequencing techniques for detecting the effects of ammonia stress (22.1 mg/L ammonia-N for 48 h) on gene expression in the hepatopancreas of M. nipponense. We generated 176,228,782 high-quality reads after eliminating adapter sequences and filtering out low-quality reads, which were assembled into 63453 unigenes. Comparative analysis of the expression profiles of the ammonia-treated and control groups identified 887 differentially expressed genes (P < 0.05), including 481 upregulated genes and 406 downregulated genes. Analyses of the GO and KEGG databases revealed significant differences between the two groups in 32 pathways. Immune-related pathways under ammonia stress included Complement and coagulation cascades, Platelet activation, B cell receptor signaling pathway, Antigen processing and presentation, Chemokine signaling pathway, NOD-like receptor signaling pathway, RIG-I-like receptor signaling pathway, T cell receptor signaling pathway and Toll-like receptor signaling pathway. Remarkably, ammonia stress altered the expression patterns of key immune genes (lectin3, syntenin, alpha-2-macroglobulin, cathepsin L, PIM3, serine protease inhibitor, suppressor of cytokine signaling-2 like protein), indicating that ammonia-stress induce immune response. These data provide new insights into the immune response of M. nipponense and pave a new way for fighting ammonia stress. The genes and pathways identified here represent valuable genetic resources for development of molecular markers and genetic breeding studies.