Identification and characterization of differentially expressed genes in hepatopancreas of oriental river prawn Macrobrachium nipponense under nitrite stress.

The oriental river prawn Macrobrachium nipponense is a highly adaptable, tolerant, and fecund freshwater prawn that inhabits a wide range of aquatic environments. The hepatopancreas of crustaceans is not only a site for secretion of digestive enzymes, and also plays important roles in several metabolic processes, such as lipid and carbohydrate metabolism. It is the main organ for the detoxification and immunity. In this study, high-throughput sequencing techniques were used to detect the effect of nitrite stress (10 mg/L nitrite-N for 48 h) on gene expression in the hepatopancreas of M. nipponense. A total of 13,769 million reads were harvested, and 94,534 transcripts were de novo assembled using Trinity software and produced 56,054 non-redundant transcripts. A total of 825 differentially expressed genes were obtained comparing 48 h nitrite stress with control group. In the analysis of GO and KEGG database, significant differences were found in 49 pathways. Immune-related pathways under nitrite stress included arginine and proline metabolism, glutamate metabolism, Jak-Stat signaling pathway, endocytosis, wnt signaling pathway, RIG-I-like receptor signaling pathway, TGF-beta signaling pathway, GnRH signaling pathway and phagosome. Apoptosis-related pathway was also significantly altered, such as lysosome and apoptosis. Remarkably, nitrite stress altered the expression patterns of key apoptosis genes (tetraspanins-like protein, LAMP, CD63, caspase 3C and Caspase 1) and immune genes (Serine proteinase-like protein, C-type lectin, daf-36, SOCS-2, alpha-2-macroglobulin), confirmed that nitrite-stress induce immune response and eventually even apoptosis. This study provided a new insight into the role of hepatopancreas in crustaceans, and further investigation will continue.