A NMR-based metabolomic approach for differentiation of hagfish dental and somatic skeletal muscles.

The hagfish dental muscle is a large and specialized element of the feeding apparatus that helps ingest food. This muscle has enzymatic activities and contractile properties different from the hagfish somatic skeletal muscle. To verify the functional relevance of protein alterations, we examined the metabolomic differentiation of hagfish dental and somatic skeletal muscles using ¹H-nuclear magnetic resonance (NMR)-based metabolomics and multivariate analysis that separated hagfish dental and somatic muscles by principal component analysis and partial least squares for discriminant analysis. Our analysis of assigned metabolites showed that anserine and taurine levels were higher in dental muscle, but creatine, fructose, glucose, glycerate, pyruvate, and succinate levels were higher in somatic muscle. We concluded that the primary energy sources of dental and somatic muscles are related to the citric acid cycle and the anaerobic glycolysis and metabolism of creatine. Thus, ¹H-NMR-based metabolomics can be integrated with the previous proteomic approach to derive biochemical and physiological information about hagfish muscles.