Natural nitrogen isotopic signature reveals deprotonation during ammonium transport across living organisms.
Investigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free\uffe2\uff80\uff90living or symbionts. Free\uffe2\uff80\uff90living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated. To address this challenge, we evaluated and improved several 15N\uffe2\uff80\uff90based methods for detecting N2 fixation activity (with a focus on soil samples) and studying active diazotrophs. We compared the acetylene reduction assay and the 15N2 tracer method and demonstrated that the latter is more sensitive in samples with low activity. Additionally, tracing 15N into microbial RNA provides much higher sensitivity compared to bulk soil analysis. Active soil diazotrophs were identified with a 15N\uffe2\uff80\uff90RNA\uffe2\uff80\uff90SIP approach optimized for environmental samples and benchmarked to 15N\uffe2\uff80\uff90DNA\uffe2\uff80\uff90SIP. Lastly, we investigated the feasibility of using SIP\uffe2\uff80\uff90Raman microspectroscopy for detecting 15N\uffe2\uff80\uff90labelled cells. Taken together, these tools allow identifying and investigating active free\uffe2\uff80\uff90living diazotrophs in a highly sensitive manner in diverse environments, from bulk to the single\uffe2\uff80\uff90cell level.
", "keywords": ["Spectrum Analysis", " Raman", "BIOLOGICAL SOIL CRUSTS", "106005 Bioinformatik", "106023 Molekularbiologie", "Nitrogen Fixation", "REVEALS", "FLUORESCENCE", "Research Articles", "Soil Microbiology", "106022 Mikrobiologie", "SPECTROSCOPY", "Bacteria", "Nitrogen Isotopes", "106003 Biodiversity research", "106023 Molecular biology", "GENETIC-REGULATION", "Archaea", "6. Clean water", "SURFACE-ENHANCED RAMAN", "COMMUNITY", "106003 Biodiversit\u00e4tsforschung", "13. Climate action", "Isotope Labeling", "106022 Microbiology", "NITROGEN-FIXATION", "106005 Bioinformatics", "RIBOSOMAL-RNA", "N-2 FIXATION"]}, "links": [{"href": "https://onlinelibrary.wiley.com/doi/pdf/10.1111/1462-2920.13954"}, {"href": "https://doi.org/10.1111/1462-2920.13954"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Microbiology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/1462-2920.13954", "name": "item", "description": "10.1111/1462-2920.13954", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/1462-2920.13954"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-12-15T00:00:00Z"}}, {"id": "10.1007/s00442-007-0711-5", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:14:59Z", "type": "Journal Article", "created": "2007-03-20", "title": "Increased Soil Stable Nitrogen Isotopic Ratio Following Phosphorus Enrichment: Historical Patterns And Tests Of Two Hypotheses In A Phosphorus-Limited Wetland", "description": "We used a P enrichment gradient in the Everglades to investigate patterns of the stable N isotopic ratio (delta(15)N) in peat profiles as an indicator of historic eutrophication of this wetland. We also tested two hypotheses to explain the effects of P on increased delta(15)N of organic matter including: (1) increased N mineralization/N loss, and (2) reduced isotopic discrimination during macrophyte N uptake. Spatial patterns of delta(15)N in surface litter and soil (0-10 cm) mimic those of the aboveground macrophytes (Typha domingensis Pers. and Cladium jamaicense Crantz). Peat profiles also show increased delta(15)N in the peat accumulated in areas near the historic P discharges since the early 1960s. The increased delta(15)N of bulk peat correlated well with both measured increases in soil total P and the historical beginning of nutrient discharges into this wetland. In 15-day bottle incubations of soil, added P had no effect on the delta(15)N of NH (4) (+) and significantly increased the delta(15)N of water-extractable organic N. Measurements of surface soils collected during a field mesocosm experiment also revealed no significant effect of P on delta(15)N even after 5 years of P addition. In contrast, delta(15)N of leaf and root tissues of hydroponically grown Typha and Cladium were shown to increase up to 12 per thousand when grown at elevated levels of P and fixed levels of N (as NH (4) (+) ). The magnitude of changes in delta(15)N resulting from altered discrimination during N uptake is significant compared with other mechanisms affecting plant delta(15)N, and suggests that this may be the dominant mechanism affecting delta(15)N of organic matter following P enrichment. The results of this study have implications for the interpretation of delta(15)N as an indicator of shifts in relative N limitation in wetland ecosystems, and also stress the importance of experimental validation in interpreting delta(15)N patterns.", "keywords": ["Time Factors", "Nitrogen Isotopes", "Nitrogen", "Water", "Phosphorus", "04 agricultural and veterinary sciences", "15. Life on land", "01 natural sciences", "6. Clean water", "Soil", "13. Climate action", "Florida", "0401 agriculture", " forestry", " and fisheries", "Fertilizers", "Ecosystem", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1007/s00442-007-0711-5"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Oecologia", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s00442-007-0711-5", "name": "item", "description": "10.1007/s00442-007-0711-5", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s00442-007-0711-5"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2007-03-21T00:00:00Z"}}, {"id": "10.1007/s00442-005-0109-1", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:14:59Z", "type": "Journal Article", "created": "2005-07-07", "title": "Plant N Capture From Pulses: Effects Of Pulse Size, Growth Rate, And Other Soil Resources", "description": "In arid ecosystems, the ability to rapidly capture nitrogen (N) from brief pulses is expected to influence plant growth, survival, and competitive ability. Theory and data suggest that N capture from pulses should depend on plant growth rate and availability of other limiting resources. Theory also predicts trade-offs in plant stress tolerance and ability to capture N from different size pulses. We injected K15NO3, to simulate small and large N pulses at three different times during the growing season into soil around the co-dominant Great Basin species Sarcobatus vermiculatus, Chrysothamnus nauseosus ssp. consimilis, and Distichlis spicata. Soils were amended with water and P in a partial factorial design. As predicted, all study species showed a comparable decline in N capture from large pulses through the season as growth rates slowed. Surprisingly, however, water and P availability differentially influenced the ability of these species to capture N from pulses. Distichlis N capture increased up to tenfold with water addition while Chrysothamnus N capture increased up to threefold with P addition. Sarcobatus N capture was not affected by water or P availability. Opposite to our prediction, Sarcobatus, the most stress tolerant species, captured less N from small pulses but more N from large pulses relative to the other species. These observations suggest that variation in N pulse timing and size can interact with variable soil water and P supply to determine how N is partitioned among co-existing Great Basin species.", "keywords": ["2. Zero hunger", "0106 biological sciences", "Nitrates", "Time Factors", "Nitrogen Isotopes", "Nitrogen", "Potassium Compounds", "Water", "Phosphorus", "15. Life on land", "Plant Roots", "01 natural sciences", "California", "Plant Leaves", "Magnoliopsida", "Soil", "Seasons", "Plant Shoots"], "contacts": [{"organization": "Jeremy J. James, James H. Richards,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1007/s00442-005-0109-1"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Oecologia", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s00442-005-0109-1", "name": "item", "description": "10.1007/s00442-005-0109-1", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s00442-005-0109-1"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-07-08T00:00:00Z"}}, {"id": "10.1007/s00442-008-1106-y", "type": "Feature", "geometry": null, "properties": {"license": "Closed Access", "updated": "2026-07-28T16:14:59Z", "type": "Journal Article", "created": "2008-07-24", "title": "Earthworms, Collembola And Residue Management Change Wheat (Triticum Aestivum) And Herbivore Pest Performance (Aphidina : Rhophalosiphum Padi)", "description": "Management practices of arable systems determine the distribution of soil organic matter thereby changing decomposer animal activity and their impact on nutrient mineralization, plant growth and plant-herbivore interactions. Decomposer-mediated changes in plant growth and insect pest performance were investigated in wheat-aphid model systems in the greenhouse. Three types of litter distribution were established: litter patch at the soil surface (simulating mulching), litter patch deeper in soil (simulating ploughing) and litter homogeneously mixed into soil (simulating disk cultivation). The litter was labelled with (15)N to follow the mineralization and uptake of nutrients by the plants. Earthworms (Aporrectodea caliginosa) and Collembola (Protaphorura armata) were included as representatives of major functional groups of decomposers. Wheat (Triticum aestivum) was planted and aphids (Rhophalosiphum padi) were introduced to leaves as one of the most important pests. Earthworms, Collembola and litter distribution affected plant growth, N acquisition and aphid development in an interactive way. Earthworms and Collembola increased biomass of seeds, shoots and roots of wheat. Increased plant growth by earthworms and Collembola was mainly due to increased transfer of N from soil (rather than litter) into plants. Despite increasing plant growth, earthworms reduced aphid reproduction. Aphid reproduction was not correlated closely with plant N concentrations, but rather with the concentration of litter N in wheat. Unexpectedly, both Collembola and earthworms predominantly affected the mobilization of N from soil organic matter, and by altering the distribution of litter earthworms reduced infestation of crops by aphids via reducing plant capture of litter N, in particular if the litter was concentrated deeper in soil. The results suggest that management practices stimulating a continuous moderate increase in nutrient mobilization from soil organic matter rather than nutrient flushes from decomposing fresh organic matter result in maximum plant growth with minimum plant pest infestation.", "keywords": ["0106 biological sciences", "2. Zero hunger", "Nitrogen Isotopes", "04 agricultural and veterinary sciences", "15. Life on land", "01 natural sciences", "Plant Leaves", "Soil", "Aphids", "Multivariate Analysis", "Animals", "0401 agriculture", " forestry", " and fisheries", "Biomass", "Oligochaeta", "Arthropods", "Ecosystem", "Triticum"], "contacts": [{"organization": "Xin Ke, Stefan Scheu,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1007/s00442-008-1106-y"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Oecologia", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s00442-008-1106-y", "name": "item", "description": "10.1007/s00442-008-1106-y", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s00442-008-1106-y"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2008-07-25T00:00:00Z"}}, {"id": "10.1007/s00442-009-1490-y", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:14:59Z", "type": "Journal Article", "created": "2010-03-06", "title": "Frequent Fire Affects Soil Nitrogen And Carbon In An African Savanna By Changing Woody Cover", "description": "When tropical and sub-tropical ecosystems burn, considerable amounts of N present in the biomass fuel may be released. This ultimately results in a loss of fixed N to the atmosphere. It is often assumed that this volatilization loss of N with frequent fire will result in a reduction of plant-available N and total system N. By changing the amount of woody biomass fire may, however, also have indirect effects on N and C dynamics. Here we consider the effects of 50 years of frequent fire on total soil N and soil organic C (SOC) and total soil N in a mesic savanna in the Kruger National Park, South Africa. We also determine how changes in woody biomass may affect total soil N and SOC. We measured soil and fine root N and C concentrations as well as total soil N and SOC pools in four burning treatments, including fire exclusion, of a long-term fire experiment. Our results show that regardless of soil depth, fire treatment had no significant effect on total soil N and SOC. Our results also show that under trees total soil N and SOC concentrations of the surface soil increase, and pools of N and SOC increase to a depth of 7 cm. However, the extent to which soil N and C dynamics differed under canopies and away from canopies was dependent on fire treatment. Our results show that the effect of fire on soil N and C is mediated both through the indirect effect of changes in woody cover and the direct effects of fire (volatilization losses of nutrients). We suggest that woody thickening in this mesic savanna will have pronounced effects on long-term N and C dynamics.", "keywords": ["0106 biological sciences", "Carbon Isotopes", "Time Factors", "Nitrogen Isotopes", "Nitrogen", "Rain", "04 agricultural and veterinary sciences", "15. Life on land", "Wood", "01 natural sciences", "Carbon", "Fires", "Trees", "Soil", "South Africa", "13. Climate action", "0401 agriculture", " forestry", " and fisheries", "Seasons", "Volatilization", "Ecosystem", "Soil Microbiology"]}, "links": [{"href": "https://doi.org/10.1007/s00442-009-1490-y"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Oecologia", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s00442-009-1490-y", "name": "item", "description": "10.1007/s00442-009-1490-y", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s00442-009-1490-y"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2010-03-07T00:00:00Z"}}, {"id": "10.1016/j.envpol.2017.06.102", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:16:16Z", "type": "Journal Article", "created": "2017-07-13", "title": "Using nitrogen concentration and isotopic composition in lichens to spatially assess the relative contribution of atmospheric nitrogen sources in complex landscapes", "description": "Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales.", "keywords": ["2. Zero hunger", "Air Pollutants", "Lichens", "Nitrogen Isotopes", "Portugal", "Atmosphere", "Nitrogen", "Urbanization", "Geographic Mapping", "Agriculture", "15. Life on land", "01 natural sciences", "6. Clean water", "Reactive nitrogen", "13. Climate action", "Nitrogen Fixation", "11. Sustainability", "Industry", "Isoscapes", "14. Life underwater", "Polution - Eutrophication", "Ecosystem", "Environmental Monitoring", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.envpol.2017.06.102"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Pollution", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.envpol.2017.06.102", "name": "item", "description": "10.1016/j.envpol.2017.06.102", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.envpol.2017.06.102"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-11-01T00:00:00Z"}}, {"id": "10.1016/j.scitotenv.2018.11.010", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:16:53Z", "type": "Journal Article", "created": "2018-11-03", "title": "\u03b415N of lichens reflects the isotopic signature of ammonia source", "description": "Although it is generally accepted that \u03b415N in lichen reflects predominating N isotope sources in the environment, confirmation of the direct correlation between lichen \u03b415N and atmospheric \u03b415N is still missing, especially under field conditions with most confounding factors controlled. To fill this gap and investigate the response of lichens with different tolerance to atmospheric N deposition, thalli of the sensitive Evernia prunastri and the tolerant Xanthoria parietina were exposed for ten weeks to different forms and doses of N in a field manipulation experiment where confounding factors were minimized. During this period, several parameters, namely total N, \u03b415N and chlorophyll a fluorescence, were measured. Under the experimental conditions, \u03b415N in lichens quantitatively responded to the \u03b415N of released gaseous ammonia (NH3). Although a high correlation between the isotopic signatures in lichen tissue and supplied N was found both in tolerant and sensitive species, chlorophyll a fluorescence indicated that the sensitive species very soon lost its photosynthetic functionality with increasing N availability. The most damaging response to the different N chemical forms was observed with dry deposition of NH3, although wet deposition of ammonium ions had a significant observable physiological impact. Conversely, there was no significant effect of nitrate ions on chlorophyll a fluorescence, implying differential sensitivity to dry deposition versus wet deposition and to ammonium versus nitrate in wet deposition. Evernia prunastri was most sensitive to NH3, then NH4+, with lowest sensitivity to NO3-. Moreover, these results confirm that lichen \u03b415N can be used to indicate the \u03b415N of atmospheric ammonia, providing a suitable tool for the interpretation of the spatial distribution of NH3 sources in relation to their \u03b415N signal.", "keywords": ["Air Pollutants", "Nitrates", "Lichens", "Nitrogen Isotopes", "Chlorophyll A", "0211 other engineering and technologies", "02 engineering and technology", "Models", " Theoretical", "chlorophyll a fluorescence", "01 natural sciences", "nitrogen deposition", "Xanthoria parietina", "Species Specificity", "Ammonia", "13. Climate action", "source spatial distribution", "biomonitoring", "physiological response", "Photosynthesis", "Environmental Monitoring", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.scitotenv.2018.11.010"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Science%20of%20The%20Total%20Environment", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.scitotenv.2018.11.010", "name": "item", "description": "10.1016/j.scitotenv.2018.11.010", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.scitotenv.2018.11.010"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-02-01T00:00:00Z"}}, {"id": "10.1038/s41559-018-0694-0", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:17:45Z", "type": "Journal Article", "created": "2018-10-19", "title": "Isotopic evidence for oligotrophication of terrestrial ecosystems", "description": "Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (\u03b415N) from more than 43,000 samples acquired over 37\u2009years, here we show that foliar N concentration declined by 9% and foliar \u03b415N declined by 0.6-1.6\u2030. Examining patterns across different climate spaces, foliar \u03b415N declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in \u03b415N of tree rings and leaves from herbarium samples over the past 75-150\u2009years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores.", "keywords": ["0106 biological sciences", "570", "Nitrogen", "[SDV]Life Sciences [q-bio]", "577", "terrestrial nitrogen", "Nutritional stress", "551", "01 natural sciences", "oligotrophication", "Isotopes", "https://purl.org/becyt/ford/1.6", "Terrestrial carbon uptake", "https://purl.org/becyt/ford/1", "Ecosystem", "580", "2. Zero hunger", "Nitrogen Isotopes", "terrestrial ecosystems", "isotopic", "Eutrophication", "Plants", "15. Life on land", "sylviculture", "Nitrogen; Nitrogen Isotopes; Plants; Ecosystem; Eutrophication", "[SDV] Life Sciences [q-bio]", "element cycles", "foliar", "13. Climate action", "nutrient availability"]}, "links": [{"href": "https://cris.unibo.it/bitstream/11585/704621/3/Craine_2018_isotopic.pdf"}, {"href": "https://www.nature.com/articles/s41559-018-0694-0.pdf"}, {"href": "https://doi.org/10.1038/s41559-018-0694-0"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Nature%20Ecology%20%26amp%3B%20Evolution", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1038/s41559-018-0694-0", "name": "item", "description": "10.1038/s41559-018-0694-0", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1038/s41559-018-0694-0"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2018-10-22T00:00:00Z"}}, {"id": "10.1080/10256010108033279", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:18:13Z", "type": "Journal Article", "created": "2007-07-07", "title": "The Effect Of Soil Temperature And Moisture On Organic Matter Decomposition And Plant Growth", "description": "The effect of soil temperature and moisture on plant growth and mineralisation of organic residues was investigated using 15N-labelled soybean residues and temperature-controlled tanks in the glasshouse. Treatments were arranged in a factorial design with: three soil temperatures (20, 26 and 30 degrees C), two soil moisture regimes (8% (-800 Kpa) or 12% (-100 Kpa)), soybean residues added (enriched at 1.82 atom % 15N excess) or no residues; and either sown with ryegrass or not sown. Pots were sampled six weeks after planting and 15N-enrichment and delta13C of the plant and soil fractions were determined. Soil inorganic N was also periodically measured. Available inorganic N increased significantly with addition of residues and generally decreased with increasing temperature. Plant dry matter decreased significantly with increase in soil temperature and increased with increasing moisture. Root-to-shoot ratio declined with increased temperature and moisture. Percentage nitrogen derived from residues (%Ndfr) increased linearly with increased temperature and moisture. Delta13C decreased linearly with increasing temperature and decreasing moisture status. There was a significant correlation between transpiration and dry matter production, but there was no correlation between water use efficiency and delta13C. The results suggest that C: N ratio of the root material effects the root turnover and in turn the water supply capacity of the root system.", "keywords": ["2. Zero hunger", "Carbon Isotopes", "Nitrogen Isotopes", "Glycine max", "Secale", "Temperature", "Water", "04 agricultural and veterinary sciences", "Plant Roots", "6. Clean water", "Soil", "Austria", "0401 agriculture", " forestry", " and fisheries", "Ecosystem"], "contacts": [{"organization": "R C Hood", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1080/10256010108033279"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Isotopes%20in%20Environmental%20and%20Health%20Studies", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1080/10256010108033279", "name": "item", "description": "10.1080/10256010108033279", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1080/10256010108033279"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2001-04-01T00:00:00Z"}}, {"id": "10.1093/treephys/21.2-3.163", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:18:23Z", "type": "Journal Article", "created": "2012-01-20", "title": "Interactive Effects Of Elevated Co2 Concentration And Nitrogen Supply On Partitioning Of Newly Fixed 13c And 15n Between Shoot And Roots Of Pedunculate Oak Seedlings (Quercus Robur)", "description": "Pedunculate oak (Quercus robur L.) seedlings were grown for 3 or 4 months (second- and third-flush stages) in greenhouses at two atmospheric CO2 concentrations ([CO2]) (350 or 700 micromol mol(-1)) and two nitrogen fertilization regimes (6.1 or 0.61 mmol N l(-1) nutrient solution). Combined effects of [CO2] and nitrogen fertilization on partitioning of newly acquired carbon (C) and nitrogen (N) were assessed by dual 13C and 15N short-term labeling of seedlings at the second- or third-flush stage of development. In the low-N treatment, root growth, but not shoot growth, was stimulated by elevated [CO2], with the result that shoot/root biomass ratio declined. At the second-flush stage, overall seedling biomass growth was increased (13%) by elevated [CO2] regardless of N fertilization. At the third-flush stage, elevated [CO2] increased growth sharply (139%) in the high-N but not the low-N treatment. Root/shoot biomass ratios were threefold higher in the low-N treatment relative to the high-N treatment. At the second-flush stage, leaf area was 45-51% greater in the high-N treatment than in the low-N treatment. At the-third flush stage, there was a positive interaction between the effects of N fertilization and [CO2] on leaf area, which was 93% greater in the high-N/elevated [CO2] treatment than in the low-N/ambient [CO2] treatment. Specific leaf area was reduced (17-25%) by elevated [CO2], whereas C and N concentrations of seedlings increased significantly in response to either elevated [CO2] or high-N fertilization. At the third-flush stage, acquisition of C and N per unit dry mass of leaf and fine root was 51 and 77% greater, respectively, in the elevated [CO2]/high-N fertilization treatment than in the ambient [CO2]/low-N fertilization treatment. However, there was dilution of leaf N in response to elevated [CO2]. Partitioning of newly acquired C and N between shoot and roots was altered by N fertilization but not [CO2]. More newly acquired C and N were partitioned to roots in the low-N treatment than in the high-N treatment.", "keywords": ["0106 biological sciences", "Carbon Isotopes", "[SDV.SA.SF]Life Sciences [q-bio]/Agricultural sciences/Silviculture", "Nitrogen Isotopes", "Nitrogen", "forestry", "Carbon Dioxide", "15. Life on land", "Plant Roots", "01 natural sciences", "Trees", "CHENE PEDONCULE", "Quercus", "Soil", "Biomass", "[SDV.SA.SF] Life Sciences [q-bio]/Agricultural sciences/Silviculture", " forestry", "Plant Shoots"]}, "links": [{"href": "https://doi.org/10.1093/treephys/21.2-3.163"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Tree%20Physiology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1093/treephys/21.2-3.163", "name": "item", "description": "10.1093/treephys/21.2-3.163", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1093/treephys/21.2-3.163"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2001-02-01T00:00:00Z"}}, {"id": "10.1093/treephys/tpu116", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:18:24Z", "type": "Journal Article", "created": "2015-01-24", "title": "Dinitrogen Fixation By Legume Shade Trees And Direct Transfer Of Fixed N To Associated Cacao In A Tropical Agroforestry System", "description": "Natural abundance of (15)N (\u03b4\u2009(15)N) was determined in bulk soil, rhizospheric soil and vegetation in an organically managed cacao (Theobroma cacao L.) plantation with Inga edulis Mart. legume trees (inga) as the principal shade for studying the nitrogen (N) cycle in the system. Cacao without contact with legumes in an adjacent plantation was used as the reference for N2 fixation and direct N transfer calculations. Bulk and rhizospheric soils contained 72 and 20%, respectively, of whole- system N. No vegetation effect on \u03b4\u2009(15)N in rhizospheric soil was detected, probably due to the high native soil N pool. Fine roots of the cacaos associated with inga contained \u223c35% of N fixed from the atmosphere (Nf) out of the total N. Leaves of all species had significantly higher \u03b4\u2009(15)N than fine roots. Twenty percent of system Nf was found in cacao suggesting direct N transfer from inga via a common mycelial network of mycorrhizal fungi or recycling of N-rich root exudates of inga. Inga had accumulated 98\u2005kg [Nf] ha(-1) during the 14-year history of the plantation. The conservative estimate of current N2 fixation rate was 41\u2005kg [Nf] ha(-1)\u2005year(-1) based on inga biomass only and 50\u2005kg [Nf] ha(-1)\u2005year(-1) based on inga and associated trees.", "keywords": ["2. Zero hunger", "Cacao", "Tropical Climate", "Nitrogen Isotopes", "Nitrogen", "Plant Exudates", "Fabaceae", "04 agricultural and veterinary sciences", "Forests", "15. Life on land", "Plant Roots", "Trees", "Plant Leaves", "Soil", "Mycorrhizae", "Nitrogen Fixation", "0401 agriculture", " forestry", " and fisheries", "Biomass", "Soil Microbiology"]}, "links": [{"href": "https://doi.org/10.1093/treephys/tpu116"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Tree%20Physiology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1093/treephys/tpu116", "name": "item", "description": "10.1093/treephys/tpu116", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1093/treephys/tpu116"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2015-01-24T00:00:00Z"}}, {"id": "10.1111/1462-2920.16213", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:18:33Z", "type": "Journal Article", "created": "2022-10-18", "title": "Application of stable\u2010isotope labelling techniques for the detection of active diazotrophs", "description": "SummaryInvestigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free\uffe2\uff80\uff90living or symbionts. Free\uffe2\uff80\uff90living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated. To address this challenge, we evaluated and improved several 15N\uffe2\uff80\uff90based methods for detecting N2 fixation activity (with a focus on soil samples) and studying active diazotrophs. We compared the acetylene reduction assay and the 15N2 tracer method and demonstrated that the latter is more sensitive in samples with low activity. Additionally, tracing 15N into microbial RNA provides much higher sensitivity compared to bulk soil analysis. Active soil diazotrophs were identified with a 15N\uffe2\uff80\uff90RNA\uffe2\uff80\uff90SIP approach optimized for environmental samples and benchmarked to 15N\uffe2\uff80\uff90DNA\uffe2\uff80\uff90SIP. Lastly, we investigated the feasibility of using SIP\uffe2\uff80\uff90Raman microspectroscopy for detecting 15N\uffe2\uff80\uff90labelled cells. Taken together, these tools allow identifying and investigating active free\uffe2\uff80\uff90living diazotrophs in a highly sensitive manner in diverse environments, from bulk to the single\uffe2\uff80\uff90cell level.Global soil nitrogen (N) cycling remains poorly understood due to its complex driving mechanisms. Here, we present a comprehensive analysis of global soil \uffce\uffb415N, a stable isotopic signature indicative of the N input\uffe2\uff80\uff93output balance, using a machine\uffe2\uff80\uff90learning approach on 10,676 observations from 2670 sites. Our findings reveal prevalent joint effects of climatic conditions, plant N\uffe2\uff80\uff90use strategies, soil properties, and other natural and anthropogenic forcings on global soil \uffce\uffb415N. The joint effects of multiple drivers govern the latitudinal distribution of soil \uffce\uffb415N, with more rapid N cycling at lower latitudes than at higher latitudes. In contrast to previous climate\uffe2\uff80\uff90focused models, our data\uffe2\uff80\uff90driven model more accurately simulates spatial changes in global soil \uffce\uffb415N, highlighting the need to consider the joint effects of multiple drivers to estimate the Earth's N budget. These insights contribute to the reconciliation of discordances among empirical, theoretical, and modeling studies on soil N cycling, as well as sustainable N management.Natural nitrogen isotopic signature reveals deprotonation during ammonium transport across living organisms.
", "keywords": ["0301 basic medicine", "570", "Potassium Channels", "Saccharomyces cerevisiae Proteins", "Nitrogen", "Ammonium deprotonation", "Saccharomyces cerevisiae", "Biochemistry", "630", "03 medical and health sciences", "Ammonia", "Ammonium Compounds", "Cation Transport Proteins", "Research Articles", "Plant Proteins", "AMT-Mep-Rh membrane proteins", "0303 health sciences", "Ion Transport", "Nitrogen Isotopes", "Arabidopsis Proteins", "Sciences bio-m\u00e9dicales et agricoles", "AMT-Mep-Rh proteins", "Hydrogen-Ion Concentration", "3. Good health", "Ammonium transport", "N isotope fractionation", "PH control", "Potassium", "Microorganisms", " Genetically-Modified", "Nitrogen (N)", "Ammonium"]}, "links": [{"href": "https://dipot.ulb.ac.be/dspace/bitstream/2013/277241/4/doi_260868.pdf"}, {"href": "https://doi.org/10.1126/sciadv.aar3599"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Science%20Advances", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1126/sciadv.aar3599", "name": "item", "description": "10.1126/sciadv.aar3599", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1126/sciadv.aar3599"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2018-09-07T00:00:00Z"}}, {"id": "10.1890/05-0836", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:19:45Z", "type": "Journal Article", "created": "2007-06-04", "title": "Bromus Tectorum Invasion Alters Nitrogen Dynamics In An Undisturbed Arid Grassland Ecosystem", "description": "The nonnative annual grass Bromus tectorum has successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical disturbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations (C3 and C4). The response of these communities was compared to an invaded/ disturbed grassland. The invaded/disturbed communities had higher surface NH4+ input in spring, whereas there were no differences for surface input of NO3-. Soil inorganic N was dominated by NH4+, but invaded sites had greater subsurface soil NO3-. Invaded sites had greater total soil N at the surface four years post-invasion in undisturbed communities, but total N was lower in the invaded/disturbed communities. Soil delta15N increased with depth in the noninvaded and recently invaded communities, whereas the invaded/disturbed communities exhibited the opposite pattern. Enriched foliar delta15N values suggest that Bromus assimilated subsurface NO3-, whereas the native grasses were restricted to surface N. A Rayleigh distillation model accurately described decomposition patterns in the noninvaded communities where soil N loss is accompanied by increasing soil delta15N; however, the invaded/ disturbed communities exhibited the opposite pattern, suggesting redistribution of N within the soil profile. This study suggests that invasion has altered the mechanisms driving nitrogen dynamics. Bromus litter decomposition and soil NO3- concentrations were greater in the invaded communities during periods of ample precipitation, and NO3- leached from the surface litter, where it was assimilated by Bromus. The primary source of N input in these communities is a biological soil crust that is removed with disturbance, and the lack of N input by the biological soil crust did not balance N loss, resulting in reduced total N in the invaded/disturbed communities. Bromus produced a positive feedback loop by leaching NO3- from decomposing Bromus litter to subsurface soil layers, accessing that deepsoil N pool with deep roots and returning that N to the surface as biomass and subsequent litter. Lack of new inputs combined with continued loss will result in lower total soil N, evidenced by the lower total soil N in the invaded/disturbed communities.", "keywords": ["ecosystem", "0106 biological sciences", "Nitrates", "550", "Nitrogen Isotopes", "Bromus", "Nitrogen", "Rain", "Population Dynamics", "arid", "Biodiversity", "04 agricultural and veterinary sciences", "15. Life on land", "Poaceae", "01 natural sciences", "nitrogen", "Soil", "Natural Resources and Conservation", "0401 agriculture", " forestry", " and fisheries", "Biomass", "Seasons", "grassland", "bromus tectorum invasion", "Environmental Sciences", "Ecosystem"], "contacts": [{"organization": "Sperry, L. J., Belnap, J., Evans, R. D.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1890/05-0836"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Ecology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1890/05-0836", "name": "item", "description": "10.1890/05-0836", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1890/05-0836"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2006-03-01T00:00:00Z"}}, {"id": "10.1890/06-1819.1", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:19:45Z", "type": "Journal Article", "created": "2007-10-23", "title": "Atmospheric Co2 And O-3 Alter The Flow Of N-15 In Developing Forest Ecosystems", "description": "Anthropogenic O3 and CO2-induced declines in soil N availability could counteract greater plant growth in a CO2-enriched atmosphere, thereby reducing net primary productivity (NPP) and the potential of terrestrial ecosystems to sequester anthropogenic CO2. Presently, it is uncertain how increasing atmospheric CO2 and O3 will alter plant N demand and the acquisition of soil N by plants as well as the microbial supply of N from soil organic matter. To address this uncertainty, we initiated an ecosystem-level 15N tracer experiment at the Rhinelander (Wisconsin, USA) free air CO2-O3 enrichment (FACE) facility to understand how projected increases in atmospheric CO2 and 03 alter the distribution and flow of N in developing northern temperate forests. Tracer amounts of 15NH4+ were applied to the forest floor of developing Populus tremuloides and P. tremuloides-Betula papyrifera communities that have been exposed to factorial CO2 and O3 treatments for seven years. One year after isotope addition, both forest communities exposed to elevated CO2 obtained greater amounts of 15N (29%) and N (40%) from soil, despite no change in soil N availability or plant N-use efficiency. As such, elevated CO2 increased the ability of plants to exploit soil for N, through the development of a larger root system. Conversely, elevated O3 decreased the amount of 15N (-15%) and N (-29%) in both communities, a response resulting from lower rates of photosynthesis, decreases in growth, and smaller root systems that acquired less soil N. Neither CO2 nor 03 altered the amount of N or 15N recovery in the forest floor, microbial biomass, or soil organic matter. Moreover, we observed no interaction between CO2 and 03 on the amount of N or 15N in any ecosystem pool, suggesting that 03 could exert a negative effect regardless of CO2 concentration. In a CO2-enriched atmosphere, greater belowground growth and a more thorough exploitation of soil for growth-limiting N is an important mechanism sustaining the enhancement of NPP in developing forests (0-8 years following establishment). However, as CO2 accumulates in the Earth's atmosphere, future O3 concentrations threaten to diminish the enhancement of plant growth, decrease plant N acquisition, and lessen the storage of anthropogenic C in temperate forests.", "keywords": ["0106 biological sciences", "Nitrogen", "Science", "Ecology and Evolutionary Biology", "Plant Roots", "01 natural sciences", "forest floor", "Soil", "developing forest", "Wisconsin", "atmospheric O3", "Ozone", "soil organic matter", "Populus tremuloides", "Biomass", "USA", "Ecosystem", "Soil Microbiology", "atmospheric CO2", "Nitrogen Isotopes", "15N", "plant N uptake", "microbial immobilization", "04 agricultural and veterinary sciences", "Carbon Dioxide", "15. Life on land", "root system size", "Populus", "N cycling", "13. Climate action", "0401 agriculture", " forestry", " and fisheries", "Betula papyrifera"]}, "links": [{"href": "https://doi.org/10.1890/06-1819.1"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Ecology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1890/06-1819.1", "name": "item", "description": "10.1890/06-1819.1", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1890/06-1819.1"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2007-10-01T00:00:00Z"}}, {"id": "10.5061/dryad.32ms0", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:21:05Z", "type": "Dataset", "title": "Data from: Convergence of soil nitrogen isotopes across global climate gradients", "description": "unspecifiedUnsummarized soil 15N datasoil 15N data for individual samples. not summarized. includes excluded data for further reference.CraineSoil15N.csvData Sourcesdata sources for soil 15N dataReferences.csv15NDataSummarizedMineral soil 15N data summarized to 0.1\u00b0 latitude and longitude", "keywords": ["2. Zero hunger", "nitrogen isotopes", "13. Climate action", "Soil texture", "15N", "soil organic matter", "Anthropocene", "15. Life on land", "6. Clean water"]}, "links": [{"href": "https://doi.org/10.5061/dryad.32ms0"}, {"rel": "self", "type": "application/geo+json", "title": "10.5061/dryad.32ms0", "name": "item", "description": "10.5061/dryad.32ms0", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5061/dryad.32ms0"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2015-03-23T00:00:00Z"}}, {"id": "10451/59767", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:23:55Z", "type": "Journal Article", "created": "2018-11-03", "title": "\u03b415N of lichens reflects the isotopic signature of ammonia source", "description": "Although it is generally accepted that \u03b415N in lichen reflects predominating N isotope sources in the environment, confirmation of the direct correlation between lichen \u03b415N and atmospheric \u03b415N is still missing, especially under field conditions with most confounding factors controlled. To fill this gap and investigate the response of lichens with different tolerance to atmospheric N deposition, thalli of the sensitive Evernia prunastri and the tolerant Xanthoria parietina were exposed for ten weeks to different forms and doses of N in a field manipulation experiment where confounding factors were minimized. During this period, several parameters, namely total N, \u03b415N and chlorophyll a fluorescence, were measured. Under the experimental conditions, \u03b415N in lichens quantitatively responded to the \u03b415N of released gaseous ammonia (NH3). Although a high correlation between the isotopic signatures in lichen tissue and supplied N was found both in tolerant and sensitive species, chlorophyll a fluorescence indicated that the sensitive species very soon lost its photosynthetic functionality with increasing N availability. The most damaging response to the different N chemical forms was observed with dry deposition of NH3, although wet deposition of ammonium ions had a significant observable physiological impact. Conversely, there was no significant effect of nitrate ions on chlorophyll a fluorescence, implying differential sensitivity to dry deposition versus wet deposition and to ammonium versus nitrate in wet deposition. Evernia prunastri was most sensitive to NH3, then NH4+, with lowest sensitivity to NO3-. Moreover, these results confirm that lichen \u03b415N can be used to indicate the \u03b415N of atmospheric ammonia, providing a suitable tool for the interpretation of the spatial distribution of NH3 sources in relation to their \u03b415N signal.", "keywords": ["Air Pollutants", "Nitrates", "Lichens", "Nitrogen Isotopes", "Chlorophyll A", "0211 other engineering and technologies", "02 engineering and technology", "Models", " Theoretical", "chlorophyll a fluorescence", "01 natural sciences", "nitrogen deposition", "Xanthoria parietina", "Species Specificity", "Ammonia", "13. Climate action", "source spatial distribution", "biomonitoring", "physiological response", "Photosynthesis", "Environmental Monitoring", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://repositorio.ulisboa.pt/bitstream/10451/59767/1/1-s2.0-S0048969718343560-main.pdf"}, {"href": "https://doi.org/10451/59767"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Science%20of%20The%20Total%20Environment", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10451/59767", "name": "item", "description": "10451/59767", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10451/59767"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-02-01T00:00:00Z"}}, {"id": "2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/277241", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:24:32Z", "type": "Journal Article", "created": "2018-09-12", "title": "Nitrogen isotope signature evidences ammonium deprotonation as a common transport mechanism for the AMT-Mep-Rh protein superfamily", "description": "Natural nitrogen isotopic signature reveals deprotonation during ammonium transport across living organisms.
Investigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free\uffe2\uff80\uff90living or symbionts. Free\uffe2\uff80\uff90living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated. To address this challenge, we evaluated and improved several 15N\uffe2\uff80\uff90based methods for detecting N2 fixation activity (with a focus on soil samples) and studying active diazotrophs. We compared the acetylene reduction assay and the 15N2 tracer method and demonstrated that the latter is more sensitive in samples with low activity. Additionally, tracing 15N into microbial RNA provides much higher sensitivity compared to bulk soil analysis. Active soil diazotrophs were identified with a 15N\uffe2\uff80\uff90RNA\uffe2\uff80\uff90SIP approach optimized for environmental samples and benchmarked to 15N\uffe2\uff80\uff90DNA\uffe2\uff80\uff90SIP. Lastly, we investigated the feasibility of using SIP\uffe2\uff80\uff90Raman microspectroscopy for detecting 15N\uffe2\uff80\uff90labelled cells. Taken together, these tools allow identifying and investigating active free\uffe2\uff80\uff90living diazotrophs in a highly sensitive manner in diverse environments, from bulk to the single\uffe2\uff80\uff90cell level.Global soil nitrogen (N) cycling remains poorly understood due to its complex driving mechanisms. Here, we present a comprehensive analysis of global soil \uffce\uffb415N, a stable isotopic signature indicative of the N input\uffe2\uff80\uff93output balance, using a machine\uffe2\uff80\uff90learning approach on 10,676 observations from 2670 sites. Our findings reveal prevalent joint effects of climatic conditions, plant N\uffe2\uff80\uff90use strategies, soil properties, and other natural and anthropogenic forcings on global soil \uffce\uffb415N. The joint effects of multiple drivers govern the latitudinal distribution of soil \uffce\uffb415N, with more rapid N cycling at lower latitudes than at higher latitudes. In contrast to previous climate\uffe2\uff80\uff90focused models, our data\uffe2\uff80\uff90driven model more accurately simulates spatial changes in global soil \uffce\uffb415N, highlighting the need to consider the joint effects of multiple drivers to estimate the Earth's N budget. These insights contribute to the reconciliation of discordances among empirical, theoretical, and modeling studies on soil N cycling, as well as sustainable N management.1 MDa) macromolecular entity. The reduced rate of reorientational motion in the bound state that precludes characterization by traditional NMR methods permits the observation of DEST. (15)N-DEST profiles are measured on a sample comprising the dark state in exchange with an NMR-visible species; in addition, the difference (\u0394R(2)) in (15)N transverse relaxation rates between this sample and a control sample comprising only the NMR-visible species is also obtained. The (15)N-DEST and \u0394R(2) data for all residues are then fitted simultaneously to the McConnell equations for various exchange models describing the residue-specific dynamics in the bound state(s) and the interconversion rate constants. Although the length of the experiments depends strongly on sample conditions, approximately 1 week of NMR spectrometer time was sufficient for full characterization of samples of amyloid-\u03b2 (A\u03b2) at concentrations of ~100 \u03bcM.", "keywords": ["Molecular Weight", "0301 basic medicine", "Kinetics", "0303 health sciences", "03 medical and health sciences", "Amyloid beta-Peptides", "Time Factors", "Nitrogen Isotopes", "Macromolecular Substances", "Nuclear Magnetic Resonance", " Biomolecular", "Software"]}, "links": [{"href": "https://doi.org/PMC3500623"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Nature%20Protocols", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "PMC3500623", "name": "item", "description": "PMC3500623", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/PMC3500623"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2012-07-19T00:00:00Z"}}, {"id": "PMC5814836", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:27:15Z", "type": "Journal Article", "created": "2022-10-18", "title": "Application of stable\u2010isotope labelling techniques for the detection of active diazotrophs", "description": "Summary
Investigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free\uffe2\uff80\uff90living or symbionts. Free\uffe2\uff80\uff90living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated. To address this challenge, we evaluated and improved several 15 N\uffe2\uff80\uff90based methods for detecting N 2 fixation activity (with a focus on soil samples) and studying active diazotrophs. We compared the acetylene reduction assay and the 15 N 2 tracer method and demonstrated that the latter is more sensitive in samples with low activity. Additionally, tracing 15 N into microbial RNA provides much higher sensitivity compared to bulk soil analysis. Active soil diazotrophs were identified with a 15 N\uffe2\uff80\uff90RNA\uffe2\uff80\uff90SIP approach optimized for environmental samples and benchmarked to 15 N\uffe2\uff80\uff90DNA\uffe2\uff80\uff90SIP. Lastly, we investigated the feasibility of using SIP\uffe2\uff80\uff90Raman microspectroscopy for detecting 15 N\uffe2\uff80\uff90labelled cells. Taken together, these tools allow identifying and investigating active free\uffe2\uff80\uff90living diazotrophs in a highly sensitive manner in diverse environments, from bulk to the single\uffe2\uff80\uff90cell level.