Differential metabolomic profiles of two closely related Leuciscinae fish, the species Ctenopharyngodon idellus and Leuciscus idus

Ctenopharyngodon idellus and Leuciscus idus are two closely related Leuciscinae fish with dramatically different physiologies, especially in terms of immunological performance. However, the intrinsic metabolic difference between these two species has not been fully discovered. In this study, the immunological indexes, such as lysozyme, superoxide dismutase, and alkaline phosphatase activities, and plasma metabolomic profiles of the two species were compared. Our study revealed significant differences in immunological indexes and metabolomic profiles between them. In C. idellus, highly abundant metabolites were enriched in galactose metabolism, pyruvate metabolism, choline metabolism, and ether lipid metabolism. By contrary, in L. idus, highly abundant metabolites were enriched in taurine and hypotaurine metabolism, glycine, serine and threonine metabolism, and glycerophospholipid metabolism. We also identified that the abundances of key immune-performancerelated metabolites, such as taurine, betaine, glutathione, gluten exorphin, and fistuloside A were higher in L. idus than in C. idellus. This result indicated that the two species presented distinct immunological performance at metabolomic level. Our study provided a snapshot of the metabolic difference between C. idellus and L. idus, and the key metabolites identified here could be utilized as immunological biomarkers for the aquaculture and selective breeding of C. idellus in the future.

Automated summary

This study compared the immunological indexes and plasma metabolomic profiles of Ctenopharyngodon idellus and Leuciscus idus, revealing significant differences in both aspects between the two species. Key immune-performance related metabolites were found to be more abundant in Leuciscus idus, suggesting potential biomarkers for immunological performance.