Combined analysis of mRNA and miRNA reveals the mechanism of pacific white shrimp (Litopenaeus vannamei) under acute alkalinity stress.

The pacific white shrimp (Litopenaeus vannamei) is now a more common aquaculture species in saline-alkali waters, while alkalinity stress is considered to be one of the stressors for shrimp. Thus, an understanding of the molecular response to alkalinity stress is critical for advancing the sustainability of culture in pacific white shrimp. In this study, we aimed to explore the response mechanism to acute high-alkaline stress by RNA-seq at low-alkaline (50 mg/L) and high-alkaline (350 mg/L). We identified 215 differentially expressed mRNAs (DEGs) and 35 differentially expressed miRNAs (DEMs), of which 180 DEGs and 28 DEMs were up-regulated, 35 DEGs and 7 DEMs were down-regulated, respectively. The DEGs were enriched in several pathways, including carbohydrate digestion and absorption, pancreatic secretion, starch and sucrose metabolism, antigen processing and presentation and glutathione metabolism. The DEMs involved in lysosome and ion transport related pathways were significantly up-regulated. We also achieved 42 DEGs, which were targeted by DEMs. miRNA-mRNA regulatory network was constructed by integrated analysis of miRNA-mRNA data. We detected several genes and miRNAs which were identified as candidate regulators of alkalinity stress, and expression patterns of key genes related to alkalinity stress in pacific white shrimp. Among these genes, the expression levels of most key genes enriched in ion regulation, digestion and immunity were increased, and the expression levels of genes enriched in metabolism were down-regulated. This research indicated that the homeostatic regulation and digestion changed significantly under acute alkaline stress, and the variations from metabolic and immunity can cope with the osmotic shock of alkalinity stress in pacific white shrimp. This study provides key clues for exploring the molecular mechanism of pacific white shrimp under acute alkalinity stress, and also gives scientific basis for the optimisation of saline-alkaline aquaculture technology.