Nitrogen FixationNitrogen IsotopesNitrogen CompoundsNitrogen CycleBlood Urea NitrogenNitrogen DioxideReactive Nitrogen SpeciesBiological TransportNitrogen OxidesPII Nitrogen Regulatory ProteinsNitratesCarbonAmmoniaFertilizersQuaternary Ammonium CompoundsKineticsGlucoseAmino AcidsGlutamate-Ammonia LigaseSoilUreaBiological Transport, ActivePlant RootsNitrogen Mustard CompoundsRadiopharmaceuticalsNitrogenaseBiomassSymbiosisHydrogen-Ion ConcentrationGlutamineBacterial ProteinsMolecular Sequence DataTime FactorsCulture MediaDeoxyglucoseMembrane Transport ProteinsPlant LeavesGene Expression Regulation, BacterialOxidation-ReductionFluorodeoxyglucose F18Iodine RadioisotopesTissue DistributionPositron-Emission TomographyLiverIronAcetyleneMutationCarbon RadioisotopesPhosphorusModels, BiologicalDigestionSodiumCarrier ProteinsTemperatureNitritesAllantoinCarbon DioxideEnergy MetabolismCells, CulturedAmmonium CompoundsGenes, BacterialPhotosynthesisFluorine RadioisotopesGlutamate SynthaseOxygenNitrate ReductaseRoot Nodules, PlantCell MembraneCyanobacteriaPoaceaeEcosystemKetoglutaric AcidsAmino Acid SequenceCarbon IsotopesDenitrificationBase SequenceTritiumEscherichia coliPlant ShootsEndocytosisAnimal FeedDose-Response Relationship, DrugBacteriaSymportersInsulinPotassiumCell LineMedicago sativaNeurotransmitter Uptake InhibitorsIntestinal AbsorptionSulfurGlutamatesCattleRats, Sprague-DawleyRhizobiumKidneySaccharomyces cerevisiaeRats, Inbred StrainsPhosphatesGene Expression Regulation, Fungal