Digital gene expression analysis in the gills of the swimming crab (Portunus trituberculatus) exposed to elevated ambient ammonia-N

• DGE was applied in gills of Portunus trituberculatus under ammonia-N stress.
• 69 genes were expressed differently under ammonia-N stress.
• Genes were categorized according to the number of expressed transcripts.
• Some important differentially expressed genes were verified using RT-qPCR.
• To understand the molecular responses of P. trituberculatus in ammonia-N stress.

Ammonia-N, which represents a major physiological challenge for crab culture, increased rapidly with time elapsed in an intensive culture system, and the gill is a key organ for crabs to exchange materials with the outside. In the present study, a digital gene expression (DGE) technology approach was applied to detect the gene expression profile of the gills in Portunus trituberculatus in response to ammonia-N for 48 h. A total of 58,336 unigenes with average length 689 bp were generated. Functional categorization of the differentially expressed genes revealed that amino acid metabolic, nucleobase metabolism, regulation of mitochondrial membrane potential, reactive oxygen species metabolic, antioxidation and immune response were the differentially regulated processes occurring during ammonia-N exposure. Seven genes related to the antioxidant system, mitochondrial electron transport, protein digestion and absorption and immune system were selected for validating the results by real-time quantitative PCR. This present study provides valuable gene information for a better understanding of molecular responses of P. trituberculatus under ammonia-N exposure.