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92 results for “nitrogen isotopes”
Seasonal dynamics of sinking organic matter in the Pacific Arctic Ocean revealed by nitrogen isotope ratios of amino acids
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Quality control for modern bone collagen stable carbon and nitrogen isotope measurements
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An isotope study on Nitrogen and Phosphorus use efficiency and movement in soil in a mimicked vermicompost-based organo-mineral fertilizer
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A non‐steady state model based on dual nitrogen and oxygen isotopes to constrain moss nitrate uptake and reduction
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Isotopic evidence for increased carbon and nitrogen exchanges between peatland plants and their symbiotic microbes with rising atmospheric CO2 concentrations since 15000 cal. yr BP
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Occurrence patterns of crop-foraging sika deer distribution in an agriculture-forest landscape revealed by nitrogen stable isotopes
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Data from: Long-term drought triggers contrasting responses of foliar stable nitrogen isotopes and soil available nitrogen in a subtropical forest
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Trophic discrimination of amino acid-specific nitrogen stable isotopes in raptor nestlings: implications for estimating trophic position
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Telemetry validated nitrogen stable isotope clocks identify ocean-to-estuarine habitat shifts in mobile organisms
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Data from: Quantifying soil gaseous nitrogen losses from nitrification and denitrification based on nitrogen isotope model
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Giant clam nitrogen isotopic data and code for N isotope model
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Five Points Plant Isotopic Values for Carbon and Nitrogen
To quantify foraging strategies in the small mammal community of the Sevilleta National Wildlife Refuge, plant samples were collected at green-up (generally March for forbs and July for grasses), and when going to seed (generally May for forbs and October for grasses). Plants were analyzed for C:N ratio, delta15N and delta13C isotopic values and for carbon and nitrogen percent content by mass in both leaf and seed. These isotopic values can be compared to mouse plasma values to determine forage width (Carbon) and forage breadth (Nitrogen). Please see Sevilleta Dataset 313 on small mammal plasma to quantify resource preferences within and between small mammal communities.
Five Points Small Mammal Blood Plasma Isotopic Values for Carbon, Nitrogen and Hydrogen
There has been little comprehensive research undertaken to quantify resource use by small mammal communities in a nutrient limited, highly stochastic ecosystem. The most abundant small mammals in this ecosystem are Heteromyids, food-caching granivores, and Cricetids, omnivores that must utilize on board fat stores as energy reserves. Heteromyid populations co-vary with primary production whereas the cricetids can forage at multiple trophic levels reducing their dependence on primary productivity. Using isotopic values for Carbon, delta13C (a ratio of 13C to 12C), of primary producers consistent within a photosynthetic pathway, C3 = -26.6 +/- 1.8Permille and C4, = -14.4 +/- 0.8Permille we can track mouse dietary assimilation of forage by plant functional type. Nitrogen isotopic values 15N (a ratio of 15N to 14N) fluctuate constantly, reflecting the landscape of primary production. Therefore, tracking nitrogen values in small mammal plasma provides a landscape level tool for studying diet by trophic level and nutritional value.
Nitrogen isotope composition of amino acids reveals trophic partitioning in two sympatric amphipods
<p>According to ecological theory two species cannot occupy the same niche. We tested the extent to which two sympatric deposit-feeding amphipods, Monoporeia affinis and Pontoporeia femorata, partition trophic resources by applying nitrogen isotope analyses (δ15N) of amino acids. We found that trophic position (TP), and resynthesis index (∑V; a proxy for degradation status of ingested material prior to assimilation by the consumer) differ between species. The surface-feeding M. affinis had higher TP and intermediate ∑V; both pointing to a large contribution of metazoans in its diet. P. femorata, which feeds in the sub-surface layers, had lower TP and a bimodal distribution of the ∑V values, supporting previous experimental evidence of a larger feeding niche. We also evaluated whether TP and ∑V values have consequences for amphipod fecundity and embryo viability and found that embryo viability in M. affinis was negatively linked to TP. Our results indicate that the amino acid-δ15N data paired with information about reproductive status are useful for detecting differences in the trophic ecology of sympatric amphipods. Key words: Compound-specific stable nitrogen isotope analyses, amino acids, trophic level, resynthesis index, reproductive status, Baltic Sea.</p>
Nitrogen isotope fractionation during archaeal ammonia oxidation: coupled estimates from measurements of residual ammonium and accumulated nitrite
<p>The naturally occurring nitrogen (N) isotopes, <sup>15</sup>N and <sup>14</sup>N, exhibit different reaction rates during many microbial N transformation processes, which results in N isotope fractionation. Such isotope effects are critical parameters for interpreting natural stable isotope abundances as proxies for biological process rates in the environment across scales. The kinetic isotope effect of ammonia oxidation (AO) to nitrite (NO<sub>2</sub><sup>-</sup>), performed by ammonia-oxidizing archaea (AOA) and bacteria (AOB), is generally ascribed to the enzyme ammonia monooxygenase (AMO), which catalyzes the first step in this process. However, the kinetic isotope effect of AMO, or ε<sub><i>AMO</i></sub><span><span> </span></span>, has been typically determined based on isotope kinetics during product formation (cumulative product, NO<sub>2</sub><sup>-</sup>) alone, which may have overestimated ε<sub><i>AMO</i></sub><span><span> </span></span> due to possible accumulation of chemical intermediates and alternative sinks of ammonia/ammonium (NH<sub>3</sub>/NH<sub>4</sub><sup>+</sup>). Here, we analyzed <sup>15</sup>N isotope fractionation during archaeal ammonia oxidation based on both isotopic changes in residual substrate (RS, <span>NH<sub>4</sub><sup>+</sup></span>) and cumulative product (CP, NO<sub>2</sub><sup>-</sup>) pools in pure cultures of the soil strain <i>Nitrososphaera viennensis</i> EN76, and in highly enriched cultures of the marine strain <i>Nitrosopumilus adriaticus</i> NF5, under non-limiting substrate conditions. We obtained ε<sub><i>AMO</i></sub><span><span> </span></span> values of 31.9-33.1‰ for both strains based on RS (<span>δ<sup>15</sup>NH<sub>4</sub><sup>+</sup>), and show that </span>estimates based on CP (δ<sup>15</sup>NO<sub>2</sub><sup>-</sup>) give larger isotope fractionation factors by 6-8‰. Complementary analyses showed that, at the end of the growth period, microbial biomass was <sup>15</sup>N-enriched<span> (10.1</span>‰),<span> whereas </span>nitrous oxide (N<sub>2</sub>O) was highly <sup>15</sup>N depleted (-38.1‰) relative to the initial substrate. Although we did not determine the isotope effect of <span>NH<sub>4</sub><sup>+</sup> </span>assimilation (biomass formation) and N<sub>2</sub>O production by AOA, our results nevertheless show that the discrepancy between ε<sub><i>AMO</i></sub><span><span> </span></span> estimates based on RS and CP might have derived from incorporation of <sup>15</sup>N-enriched residual NH<sub>4</sub><sup>+</sup> after AMO reaction into microbial biomass, and that N<sub>2</sub>O production did not affect isotope fractionation estimates significantly.</p>
Food sources of benthic communities at the Caiwei Guyot and Yap Trench, northwestern Pacific Ocean: inferences from carbon and nitrogen isotopes
<p>To investigate nutritional resources for benthic communities at two sites in the northwestern Pacific Ocean (the Caiwei Guyot and the Yap Trench), stable isotopes of carbon and nitrogen (δ<sup>13</sup>C and δ<sup>15</sup>N) were measured in the tissues of megabenthic consumers (Porifera, Asteroidea, Crinoidea, Holothuroidea, Ophiuroidea, Gammaridea, and Actiniaria) as well as four potential food sources (suspended particles, sinking particles, zooplankton, and sedimentary organic matter, SOM). Fast-sinking particles are generally thought to be the primary food source for benthic consumers, but that paradigm does not seem to apply at these abyssal sites. Here, the δ<sup>13</sup>C and δ<sup>15</sup>N signatures of fast-sinking particles (as collected by sediment traps; δ<sup>13</sup>C = −24.1 to −22.6‰, δ<sup>15</sup>N = 1.4 to 5.4‰) were significantly lower than those of the megabenthos (δ<sup>13</sup>C = −20.1 to −16.1‰, δ<sup>15</sup>N = 10.2 to 17.9‰), indicating that these particles are not likely a direct food source for the animals. Buoyant particles (and slow-sinking particles), on the other hand, seem to be a significant direct food source for the megabenthos. Sedimentary organic matter and zooplankton are also important direct food sources. Trophic level analysis similarly indicates a diversity of food sources and suggests that for at least some animals, microbes (e.g., bacteria) may be a food source as well.</p>
DATASET: Isotope Ratios, Carbon and Nitrogen Concentrations, and Phytoplankton Composition Data from the ACE Expedition
<p>This dataset represents the averaged observations derived from the Antarctic Circumnavigation Expedition (ACE - 2016/2017) and has been utilized for the analyses presented in the publication: "A circum-Antarctic plankton isoscape: Carbon export potential across the summertime Southern Ocean". It encompasses a comprehensive suite of biogeochemical measurements, specifically the isotopic ratios (δ13C, δ15N) and concentrations of carbon and nitrogen in Suspended Particulate Matter (SPM). Additionally, it includes data from High-Performance Liquid Chromatography (HPLC) analyses (i.e., Total Chl-a and fractions of pico-, nano-, and micro-phytoplankton).</p><p>This dataset also contains the outputs of our calculations based on the two-endmember isotope mixing model (Fawcett et al., 2011), complemented by the Rayleigh model (Mariotti et al., 1981) to deduce the fraction of phytoplankton biomass originating from new nitrogen source (New Production).</p>
Dataset for "Low blank sampling method for measurement of the nitrogen isotopic composition of atmospheric nitrogen oxide "
<p>The final dataset used in the manuscript "Low blank sampling method for measurement of the nitrogen isotopic composition of atmospheric nitrogen oxide<sub> </sub>" by Kamezaki et al. The dataset contains NOx concentration and nitrogen isotopic composition observed at Yoyogi and Tsukuba sites in Japan. Additionally, the data used in the paper are also included. Raw data are available upon request from the author.</p>
Nitrogen isotope ratios of nitrate, ammonium, and amino acids in sinking particles in the Northwestern North Pacific
<p>The database includes sample information and nitrogen isotope measurements of nitrate, ammonium, and amino acids in sinking particles in the Northwestern North Pacific. The sinking particles were collected in sediment traps moored at depths of 200, 500, and 4,810 m at station K2 (47°N, 160°E; water depth, ~5,200 m). The seawater was sampled with a plastic bucket for the surface and Niskin-X sampling bottles for water below the surface at stations K2 and KNOT (44°N, 155°E). The model package of a 1D nitrogen isotope model includes model source code written in Fortran 90, forcing, and initial condition at station K2.</p>
Bulk and amino acid nitrogen specific isotope data from particulate organic matter and mesozooplankton (1000-2000 µm) from the Mekong River plume and southern South China Sea
<p><strong><span><span>The mean trophic position (TP) of mesozooplankton largely determines how much mass and energy is available for higher trophic levels like fish. Unfortunately, the ratio of herbivores to carnivores in mesozooplankton is difficult to identify in field samples. Here we investigated changes in the mean TP of mesozooplankton in a highly dynamic environment encompassing four distinct habitats in </span></span></strong>the southern South China Sea:<strong> </strong><span>the </span>Mekong River plume, coastal upwelling region, shelf waters, and offshore oceanic waters<strong><span>. </span></strong><span>We used a set of parameters derived from bulk and amino acid nitrogen stable isotopes from particulate organic matter (POM) and four mesozooplankton size fractions to identify changes in the nitrogen source and structure of the planktonic food web across these habitats.</span> We found clear indications of a shift in N sources for biological production from nitrate in near-coastal waters towards an increase in diazotroph-N inputs in oceanic waters where diazotrophs shaped the phytoplankton community. The shift in N source was accompanied by a lengthening of the food chain (increase in the TP), which may provide further support for the connection between diazotrophy and the indirect routing of N through the marine food web. Our combined bulk and amino acid δ<sup>15</sup>N approach also allowed us to estimate the trophic enrichment (TE) of mesozooplankton across the entire regional ecosystem. When put in the context of literature values, our high TE of 5.1‰ suggested a link between ecosystem heterogeneity and the less efficient transfer of mass and energy across trophic levels.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.