Cell NucleusIsotopesIsotope LabelingNitrogen IsotopesOxygen IsotopesCarbon IsotopesZinc IsotopesSulfur IsotopesDeuteriumIron IsotopesStrontium IsotopesEcosystemMass SpectrometryRadioisotope Dilution TechniquePopulation DensityIndicator Dilution TechniquesBiodiversityProteomicsRNA, MessengerPopulation DynamicsKineticsGas Chromatography-Mass SpectrometryMolecular Sequence DataGeologic SedimentsChromatography, LiquidFood ChainProteomeSeawaterTandem Mass SpectrometryEvolution, PlanetaryMercury IsotopesTreesBacteria