Abstract

Metabolomics is a top-down, holistic approach to assess organismal health status by addressing the complete biochemical system through metabolite profiles in biofluids (urine, plasma/serum) and tissues. A metabolic profile represents the endogenous small molecular weight compounds like amino acids, organic acids, sugars, and phosphate energy molecules that correspond to the physiological state of the organism. Perturbations to the "normal/healthy" organism due to stressors (diet, toxicity, infection, or disease) can be detected in the subtle changes of the metabolic profile resulting in potential biomarkers of the stress. Hydrogen (¹H) nuclear magnetic resonance (NMR) can provide a comprehensive unbiased "snapshot" of all the metabolites in a biofluid or tissue sample without the need for extensive sample preparation. Because of the complex mixture of compounds detected in the NMR spectra and the large number of samples needed for statistical significance, pattern recognition tools and multivariate statistics are used to visualize and extract meaningful information relating to the biochemical responses to a challenge (Figure 1).

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Figure 1. A pictoral description of the systems biology field of study called 'metabolomics'. Metabolomics investigates important biological questions with analytical chemistry techniques (i.e., NMR data). Pattern recognition tools and multivariate statistics (principal components analysis) are used to analyze the large data sets resulting in metabolite signatures that characterize the physiological/ health status.

Metabolomics was developed for and has advanced human health research in areas such as disease diagnosis, drug compatibility, and nutritional studies. We have adopted this useful technique to assess health in the marine environment. In marine non-model organisms, where little biochemical, genomic or proteomic data exists, metabolomics permits chemical characterization of the biochemical processes of the organism at a given time and a characterization of the range of health parameters one would expect in changing environments. By probing the health status of a myriad of species, we believe that metabolomic studies may aid in describing organismal health norms, extrapolating to reveal ecosystem health condition and serve as an enviromental monitoring tool.

To date, we have been involved in metabolomic studies with several marine organisms. We have investigated oxidative stresses by infection and by chemical insult in Atlantic blue crabs (Callinectes sapidus); Pacific white shrimp (Litopanaeus vannamei) metabolic changes were assessed in response to hypoxia; the metabolic changes during pathogenicity were evaluated in the coral bleaching bacteria Vibrio coralliilyticus; cultured cobia health (Rachycentron canadum) was assessed in response to alternative fishmeal diets; and metabolomic studies were conducted on live-captured Atlantic bottlenose dolphins (Tursiops truncatus) for a general measure of health for these sentinel organisms.

Acknowledgements

The authors would like to thank Dr. Arezue Boroujerdi, Dr. Elizabeth Pollock, undergraduate students Sara Lien Huynh, Alton Sutter, David Stansyk, Alex Meyers, Jonathan Jeffries, Jace Jenson, and Sarah Newton. We also acknowledge valuable collaborations with Drs. Pat Fair, and Mike Fulton (NOAA); Dr. John Leffler (SCDNR); Drs. Pamela Morris, Karen Burnett, and Lou Burnett of the Hollings Marine Laboratory.