Analysis of circRNA expression profile of Litopenaeus vannamei under pH and alkalinity interactive stress and verification of novel_circ_021024 and novel_circ_004981 regulating stress compounds metabolism

Abstract

The global issue of salinization has made the use of saline-alkaline water in aquaculture increasingly vital. CircRNAs are a new type of endogenous non-coding RNA. Under high saline-alkaline stress, how circRNAs regulate the stress response of Litopenaeus vannamei, especially the mechanism of its immune and metabolic functions, is still unclear. This study aimed to analyze the expression profile of circRNAs and explore their response mechanisms in L. vannamei under the combined influence of high alkalinity and high pH. The results indicated that 127, 157, and 146 differentially expressed circRNAs (DECs) and 1401, 1547, and 1540 differentially expressed mRNAs (DEGs) were identified in the high-pH, alkalinity, and interaction groups, respectively. KEGG enrichment analysis revealed that DECs were mainly enriched in pathways such as sulfur metabolism, glycerophospholipids, and oxidative phosphorylation. The activities of antioxidant-related enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH - PX), increased, while the activities of energy - metabolism-related enzymes, like hexokinase (HK) and pyruvate kinase (PK), decreased. By combining weighted gene-related network analysis (WGCNA) with circRNA - mRNA data, it was found that the expression levels of essential genes related to metabolisms, such as novel_circ_007011, novel_circ_004981, and novel_circ_021024, declined. Gene-silencing experiments demonstrated that novel_circ_004981 and novel_circ_021024 could regulate the expression of glutathione peroxidase (GPx) and carbonic anhydrase - 3 (cah - 3) and further regulate the metabolic pathway and antioxidant system of L. vannamei. This study provides theoretical support for further understanding the stress-response mechanisms of circRNAs in L. vannamei under high-pH and alkalinity stress and offers a scientific basis for the development of saline-alkali aquaculture.