Abstract:
The labeled atoms of carbon and nitrogen are widely used in biology, biochemistry, and soil science. Both radioactive (14C) and stable (12C, 13C, 15N) isotopes are used as such labels. Recently, an increase in mass spectrometry sensitivity made it possible to study natural ratios of carbon (13C/12C) and nitrogen ( 15N/14N) stable isotopes in various biological objects. Since most biological processes discriminate isotopes, i.e., use lighter isotopes for fermentative reactions and leave heavier isotopes in substrate, the study of isotopic compositions of various habitats of organisms yields information on intensity and direction of biological processes.
