INTERNATIONAL NMR-BASED ENVIRONMENTAL METABOLOMICS INTERCOMPARISON EXERCISE II

 

Tracey B. Schock1, Arezue Boroujerdi1, Mark R. Viant2 and Daniel W. Bearden1

 

1National Institute of Standards and Technology, Analytical Chemistry Division, Hollings Marine Laboratory, Charleston, SC 29412

2NERC Biomolecular Analysis Facility – Birmingham node (NBAF-B) for Environmental Metabolomics; University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

 

NMR-based environmental metabolomics is based on detecting metabolic changes in organisms in response to environmental challenges.  As a tool for risk assessment and environmental monitoring, it is important to ensure precision and efficacy in the applied techniques, as well as to have the ability to yield reproducible results across laboratories.  The first international intercomparison exercise for NMR-based environmental metabolomics1 included seven laboratories on three continents evaluating synthetic metabolite mixtures and European flounder (Platichthys flesus) liver extracts from clean and contaminated sites with 1H NMR.  Factors evaluated in the exercise included sample preparation, NMR data collection at multiple NMR-field strengths, quantitative evaluation and multivariate data analysis (principal component analysis).  This intercomparison exercise was successful in that both principal components analyses (PCA) results and biomarker discovery were similar for all laboratories.  A second exercise is being planned to build on lessons learned in the previous exercise and to expand the depth and breadth of the study.  Participants will be asked to process and analyze two classes of materials with a set of robust NMR experiments and data analysis protocols.  In an optional second segment, the participants will be asked to collect more varied experimental data and process the data using more advanced schemes.  In preparing for the exercise, a useful biological material that clearly separates metabolomes of control from challenged organism was required.  Cobia (Rachycentron canadum) fillet plugs, from a study designed to evaluate the ability to enhance farmed fish products for human health benefits through dietary manipulation of the fish, were analyzed.  Metabolites were extracted with a chloroform:methanol:water method from eight cobia fillets from Day 0 on the control diet (commercially available), eight fillets from Day 98 (last time point) on the control diet, and eight fillets from Day 98 on a reduced fishmeal diet (labeled FM25).  To ensure the tissue extraction technique was reproducible, a NIST standard reference material (SRM 1946) was extracted alongside the fillets (one SRM per batch of 6 fillets).  Polar metabolites were analyzed on Bruker Avance II 700 and 800 MHz magnets.  PCA scores plots showed distinct metabolic differences between cobia fillets from the control diet and those from the reduced fishmeal diet, indicating that these tissues will be suitable as complex biological samples in the intercomparison exercise.  Large scale tissue homogenization and extraction is currently underway in preparation for distributing samples to participating labs by summer 2010. 

 

Reference

1) International NMR-Based Environmental Metabolomics Intercomparison Exercise, Mark R. Viant, Daniel W. Bearden, Jacob G. Bundy, Ian W. Burton, Timothy W. Collette, Drew R. Ekman, Vilnis Ezernieks, Tobias K. Karakach, Ching Yu Lin, Simone Rochfort, Jeffrey S. de Ropp, Quincy Teng, Ronald S. Tjeerdema, John A. Walter, and Huifeng Wu Environ. Sci. Technol., 2009, 43 (1), 219-225 • DOI: 10.1021/es802198z • Publication Date (Web): 25 November 2008