Comparative transcriptome analysis reveals the expression and characterization of digestive enzyme genes in the hepatopancreas of the Chinese mitten crab

Abstract

The Chinese mitten crab Eriocheir japonica sinensis is one of the most common aquaculture species cultivated in China. The crab is an omnivore, and its hepatopancreas absorbs and stores nutrients. The aim of this study was to elucidate the expressions of the digestive enzyme genes and determine their respective roles in regulating digestive capacity in E. j. sinensis. We sequenced the hepatopancreatic transcriptomes of crabs fed a meat diet (MD), a vegetarian diet (VD), or a mixed diet (MV) and compared the gene expression patterns of these three groups of crabs. A total of 305,887 unigenes were obtained, of which 8747, 10,963, and 8877 were significantly differentially expressed in the comparisons between the MD and MV, VD and MV, and MD and VD diets, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) database-based enrichment analysis revealed that the differentially expressed gene (DEG) responses in the hepatopancreases to the MD mainly involved the “pancreatic secretion,” “glutathione metabolism,” “sphingolipid metabolism,” “fatty acid metabolism,” and “glycerolipid metabolism pathways.” DEG responses to the VD based on KEGG analysis mainly involved the “galactose metabolism,” “starch and sucrose metabolism,” and “fructose and mannose metabolism” pathways. The key digestive enzymes, including trypsin, β-glucosidase, chitinase, and triacylglycerol lipase, were identified. Our results further our understanding of crustacean hepatopancreatic functions during food digestion and provide resources for further studies regarding the molecular basis of omnivorous diets in crustaceans.