Nuclear magnetic resonance identifies molecules that include hydrogen atoms, which give off signals, as unique as fingerprints, which indicate the arrangement and identity of other atoms with the molecule. MRI (magnetic resonance imaging) avails of this effect to generate images of soft tissues. Such chemical fingerprints allow the identification of key metabolites (metabolic molecules).
The blood of two long-lived genetic mice strains (Irs1 null and Ames dwarf) as well as dietary restricted mice was metabolic profiled. Defined metabolites are altered in the same way across the three long-lived groups. For instance the concentration of specific lipids as well as choline and trimethylamine are reduced in all three models [http://www.csc.mrc.ac.uk/News/News/SignaturesLongevity/].
Wijeyesekera, A., Selman, C., Barton, R. H. H., Holmes, E., Withers, D., Nicholson, J. K. K. (2012). Metabotyping of Long-Lived mice using 1H NMR spectroscopy. Journal of Proteome Research