NMR-BASED METABOLOMICS IDENTIFICATION OF A POTENTIAL METABOLIC BIOMARKER OF NUTRITIONAL STRESS IN RED DRUM Sciaenops ocellatus FED GRADED LEVELS OF SOYBEAN MEAL

Fabio Casu*, Daniel W. Bearden, Aaron Watson, Justin Yost, John W. Leffler, T. Gibson Gaylord, Frederic T. Barrows, Paul A. Sandifer and Michael R. Denson
 
National Institute of Standards and Technology
Hollings Marine Laboratory
Charleston, SC 29412, USA
fabio.casu@noaa.gov
 

Metabolomics is the study of metabolites present in plant and animal tissues and biofluids (the "metabolome"). The metabolome is strongly connected to the physiological status of the organism and reflects the influence of multiple internal and external factors. Diet can significantly affect the metabolome, and careful analytical measurements can detect dietary effects on the biochemical pathways associated with normal health and growth. Nuclear Magnetic Resonance (NMR) spectroscopy is an analytical technique that can be used to measure these metabolites. NMR-based metabolomics can be used to detect potential biomarkers that can be indicative of specific nutritional deficiencies.

During a 12-week feeding trial, we investigated metabolic changes in juvenile red drum induced by graded levels of soybean meal (SBM0 %, 15 %, 30 %, 45 % and 60 %) in extruded, fishmeal-free diets using NMR-based metabolomics. Liver, muscle, intestine and plasma samples were collected weekly and analyzed to provide a "snapshot" of the metabolome at different time points, resulting in a "metabolic trajectory". Metabolomic results suggest that a nutritional deficiency might have occurred at high levels (45 % to 60 %) of soybean meal inclusion1.

By comparing metabolic profiles at the end of the study (Figure 1), we identified a metabolite whose levels were significantly increased at high SBM levels. This compound (N-formimino-L-glutamate (FIGLU)) has been associated with vitamin deficiencies (specifically vitamin B12 and/or folate) in mammals, but not previously investigated in fish. Our results suggest that this metabolite may be a biomarker of potential dietary stress in red drum that allows for the optimization of soy-based formulations in red drum.

1.      Casu, F.; Watson, A. M.; Yost, J.; Leffler, J. W.; Gaylord, T. G.; Barrows, F. T.; Sandifer, P. A.; Denson, M. R.; Bearden, D. W., Investigation of Graded-Level Soybean Meal Diets in Red Drum (Sciaenops ocellatus) using NMR-based Metabolomics Analysis. JWAS 2017, Submitted.