Metabolomic analysis of Hepatopancreas revealed the metabolic responses of clam Cyclina sinensis towards high temperature stress

Temperature is an important environment factors which affects the metabolism, development and survival of clams. In this study, we first investigated the adaptability of several economic clams to high temperature, and Cyclina sinensis showed strong adaptability to heat stress. To explore the response mechanism of C. sinensis to acute high temperature, the metabolomic analysis of hepatopancreas was conducted. A total 1271 metabolites were identified in the metabolomic data from all samples. The analysis results showed that high temperature caused changes in amino acids and derivatives, fatty acyls, peptides, phosphatidylcholines in heat stressed (30 and 34°C) clams compared to control group (26°C) clams. Then, we found that significantly differential metabolites (SDMs) were mainly enriched in β-alanine metabolism, pantothenate and CoA biosynthesis, biosynthesis of amino acids and metabolic pathways. The results showed that the content of β-alanine, some phosphatidylcholines (PCs) and antibacterial metabolites were upregulated while lysophosphatidylcholine (LPC) was downregulated under high temperature stress. The next, the expression of some genes related to production and metabolism of β-alanine was detected by qPCR and the results showed that the expression of the carnosine synthase ( CARNS ) was significantly downregulated under heat stress. Overall, our study provides a valuable resource and novel insights into the metabolic regulatory mechanisms to high temperature stress in clams C. sinensis and would contribute to finding the heat-tolerant candidate metabolites which were helpful to breeding of heat-resistance clams. • The clam Cyclina sinensis showed strong adaptability to acute high temperature stress. • Metabolic profiles of C. sinensis under acute high-temperature stress. • Significantly differential metabolites were enriched in β-alanine metabolism, pantothenate and CoA biosynthesis. • Some significantly differential metabolites were involved in energy metabolism, immune function, and ROS scavenging.