Isotope labeling experiments in metabolomics and fluxomics.

Metabolomics, the study of all the small molecules in and outside a cell and fluxomics, comprising all conversion rates in a cell, are increasingly used in fundamental and applied sciences to unravel structures and activities of cellular networks and their regulation, to investigate mechanisms of diseases and toxicity, and to improve producing strains among other applications. For both fluxomics and metabolomics the application of isotopes became almost indispensable. Their use in these techniques is discussed, focusing primarily on studies applying stable isotopes and using mass spectrometry. This includes the underlying principles, experimental and computational methods used, and examples of application.