The effects of ammonia stress exposure on protein degradation, immune response, degradation of nitrogen-containing compounds and energy metabolism of Chinese mitten crab.

Abstract

The Chinese mitten crab is one of the most economically important crabs that are widely farmed in China. Ammonia, which is a main physiological challenge for crab culture, grows rapidly in the intensive culture system overtime, but little information is available with Chinese mitten crab on the molecular mechanisms. Therefore, to understand the mechanism of response to ammonia stress in Eriocheir japonica sinensis, comparative transcriptome analysis was used to identify the key genes and pathways in hepatopancreas challenged with ammonia stress (325.07mg/L NH4Cl). By sequencing the transcriptome hepatopancreas of E. j. sinensis treated with ammonia, 366,472 unigenes were obtained and annotated into several public libraries for later analyses. Subsequently, 1775 differentially expressed genes (DEGs) were identified according to comparative transcriptome analysis, of which 307 were up-regulated and 1468 were down-regulated. According to the DEGs of GO and KEGG enrichment analyses, we focused on four aspects of significant enrichment in this study: protein degradation, immune response, degradation of nitrogen-containing compounds and energy metabolism. The genes involved in protein degradation and energy metabolism process showed a significant decrease which was consisting of overall biological activity of E. j. sinensis decreased. In addition, five genes involved in high concentration of ammonia were discovered and validated by qRT-PCR. This study will help us understand the molecular mechanisms of E. j. sinensis under high ammonia exposure and provide valuable information to the future research of other crabs with ammonia exposure.