Metabolomics of Strongylocentrotus intermedius fatty acid metabolism under high-temperature stress conditions

Abstract

The gonads of sea urchins are the primary source of nutritional value; these gonads are rich in nutrients, particularly PUFAs, which are essential for the gonads' growth and development as well as their nutritional worth. Strongylocentrotus intermedius grows best at a temperature of 15 °C. However, the contemporary climate is unstable, and abrupt fluctuations in water temperature are frequently brought on by extreme weather. Therefore, S. intermedius were exposed to several temperature gradients (15 °C, 20 °C, and 25 °C) and varied stress periods (7 days, 30 days) in order to investigate the impact of temperature on the concentration of fatty acids in the gonads of S. intermedius. The following are the study's primary findings: The fatty acid (FA) content of the S. intermedius is investigated at three temperatures (15 °C (control), 20 °C, and 25 °C) after exposure for 7 and 30 days. Urchin gonads were metabolized using ultra-performance liquid chromatography coupled with high-resolution mass spectrometry. Relative to the control, after 7 d temperature stress at 20 °C, 33 FA metabolites were differentially expressed, of which mono-unsaturated fatty acids (MUFA), medium-chain fatty acids (MCFA), and most long-chain fatty acids (LCFA) were downregulated, and saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) (ω-3 PUFA and ω-6 PUFA) were upregulated (P < 0.05); at 25 °C, 16 FA metabolites were differentially expressed, of which MCFA, ω-3 PUFA, and ω-6 PUFA were upregulated (P < 0.05), and short-chain fatty acids (SCFA), MCFA, MUFA, and some LCFA were downregulated. KEGG metabolic pathway analysis annotated FA metabolites to 62 metabolic pathways. Biosynthetic metabolic pathways that are significantly enriched in unsaturated FAs. Relative to the control, after 30 d temperature stress at 20 °C, four FA metabolites were differentially expressed, of which ω-6 PUFA was downregulated (P < 0.05), and other PUFAs were upregulated (P < 0.05); at 25 °C, 10 FA metabolites were differentially expressed, of which mid-chain SFA, ω-3 PUFA, ω-6 PUFA, and ω-6 MUFA were downgraded (P < 0.05), and short-chain MUFA and long-chain SFA were upregulated (P < 0.05). After 30 d exposure to elevated temperatures, differentially expressed metabolites of FAs are annotated to five KEGG metabolic pathways. S. intermedius may reduce energy consumption by regulating FA metabolism, where ω-3 and ω-6 PUFA may be prioritized for oxidative energy supply. As exposure to temperature stress increases, urchins are unable to synthesize more ω-3 PUFA to deal with inflammation. Changes in FA composition can be used as a sensitive early warning biometric indicator.