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Results for “nitrogen partitioning”

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At least 19 recordsLinked to original sources
PubMed1979

Concentrating capacity of the kidney and nitrogen partition in the urine in Perodicticus potto (Prosimii, Lorisidae, Lorisinae).

The concentrating ability of the kidney in Perodicticus potto was investigated. As the relation between this capacity and the thickness of the medulla has been stressed by Schmidt-Nielsen & O'Dell, the size of the various layers in the kidney was measured. Based on our observation that the potto may excrete uric acid in fairly high concentrations, the partition of nitrogen in the urine was also explored.

Animals↗
PubMed2026

The domestication-associated WHP10 tandem cluster of amino acid transporter genes enhances whole-plant protein accumulation in maize.

Improving protein accumulation in maize is essential for sustainable agriculture, yet the regulatory mechanisms governing the intermediate "flow" of organic nitrogen remain elusive. Here, we show that the maize stem acts as a regulatory node for nitrogen allocation. By integrating spatial transcriptomics and metabolomics with quantitative genetics, we demonstrate that a transport-oriented stem program orchestrates the high-protein phenotype of the wild maize accession Ames21814. We identified a major locus, Whole-plant High Protein 10 (WHP10), that encodes a tandemly duplicated cluster of amino acid transporter genes. WHP10 exhibits strong vascular-biased expression, driven by promoter divergence that enhances the wild allele's activity. Functional assays and genetic validation support a model in which the WHP10 cluster facilitates the transport of multiple nitrogen-rich amino acids, thereby contributing to vascular-associated amino acid transport and post-uptake organic-nitrogen partitioning. Our findings establish stem flow as a regulatory layer for protein accumulation and identify WHP10 as a high-value target for precision breeding to enhance whole-plant protein accumulation without compromising grain yield.

Zea mays↗
PubMed1979

A simple technique to estimate severity of stress.

A simple procedure to estimate stress has been developed based upon 24 hour urine urea nitrogen excretion. This catabolic index partitions total urea excretion into that resulting from dietary protein intake and obligatory urea excretion and that due to an increase in endogenous protein catabolism: catabolic index equals 24 hour urine urea nitrogen excretion - (0.5 dietary nitrogen intake + 3 grams) where an index of less than zero represents no significant stress; an index of zero to 5, moderate stress, and an index greater than 5, severe stress. In 111 persons, significant differences were noted in the catabolic index, reflecting varying degrees of stress, nutrient intake and nutritional status. The catabolic index may have useful diagnostic and treatment applications.

Dietary Proteins↗
PubMed1979

Solubility and partition coefficients for gases in rabbit brain and blood.

Solubility and partition coefficients for argon, methane, neon, nitrogen, and sulfur hexafluoride in normal saline, rabbit blood, and exsanguinated rabbit brain were determined in a two-step process that involved equilibration of the various aliquots, and subsequent analysis by gas chromatography. Brain-blood partition coefficient was specifically higher than one for argon, neon, and sulfur hexafluoride, and questionably significant (P less than 0.025) for nitrogen.

Animals↗
PubMed2026

Ecological Filtering by Tuber Compartments Shapes Stable Core Microbiomes That Underpin Potato Plant Growth Across Environments.

Harnessing plant microbiomes for sustainable agriculture requires understanding not only whether they can boost crop performance, but also how ecological processes govern their assembly, stability, and functional contributions across environments. While we previously showed that seed tuber microbiomes can predict potato vigour using machine learning, it remained unclear how ecological processes shape tuber microbiome stability and functionality across host genotypes, tuber compartments, soil types, and years. Here, we analyzed the national-scale dataset of 240 field-collected potato seedlots, spanning six genotypes, two soil types, and two growing years, with a focus on the spatially distinct heel and eye compartments of the potato tuber. By profiling over 1200 bacterial and fungal communities and linking microbiome composition to plant performance, we show that plant genotype and tuber compartment are the strongest determinants of microbial diversity and composition. Compartment-specific enrichment of functional traits revealed spatial partitioning of microbial functions, with organic compound conversion and nitrogen cycling dominant in the heel, and energy metabolism enriched in the eye. Applying a macroecological abundance-occupancy framework, we identified a stable core microbiome of bacterial and fungal taxa that persisted across all environments and years. These core members were more strongly associated with plant growth-related traits than non-core taxa, and core taxa in different tuber compartments showed distinct correlations with taxa of potential pathogenic relevance. Together, our findings demonstrate that tuber compartments act as ecological filters that structure persistent, functionally specialised microbiomes linked to plant growth-related traits across environments. By providing an ecological and functional framework for compartment-resolved, stable core microbiomes, this study advances mechanistic understanding of plant-microbe interactions and identifies stable microbial partners as promising targets for improving potato resilience and productivity.

Journal Article↗
PubMed2026

Phosphorus modulates starch granule development and metabolic partitioning in wheat grain: Insights from SGAP proteomics and nutrition and processing quality.

This study investigates how phosphorus (P) levels are associated with carbon-nitrogen metabolism in wheat grains. Optimal P application (105 kg P₂O₅ ha⁻¹) was associated with enhanced pericarp-endosperm coordination, increased carbon allocation to the endosperm, and early B‑type starch granule formation. Starch granule‑associated protein (SGAP) proteomics showed that optimal P upregulated cytoskeletal and starch‑synthesis proteins bound to starch granules in the endosperm, while reducing storage protein degradation‑related SGAPs in the pericarp. These metabolic adjustments were correlated with increased grain‑filling intensity and duration, and were associated with the highest theoretical grain weight (50.70 mg). Furthermore, optimal P was associated with enrichment of amino acid biosynthesis pathways and with higher levels of essential amino acids (e.g., lysine and threonine by 17.0--26.8%) and an improved essential amino acid profile without altering total protein content. In contrast, excessive P (210 kg P₂O₅ ha⁻¹) was associated with disrupted inter‑tissue coordination but did not simply impair grain filling; instead, HP corresponded to a unique developmental program: it was linked to an early burst of C‑type starch granules (0∼5 µm) at 7 DPA, yet by maturity achieved the highest proportion of large A‑type granules (56.8%) and the highest total starch content (63.5%), together with elevated endosperm phosphorus at 14 DPA and enrichment of spliceosome‑related pathways. HP also showed higher levels of several functional amino acids (glutamate, cysteine, histidine, proline) compared to P0. However, HP was associated with a higher gliadin/globulin ratio and did not improve grain yield. These findings suggest that phosphorus supply is associated with grain quality through tissue‑specific metabolic reprogramming, and that precision management-rather than maximized application-warrants consideration for optimizing both yield and processing quality.

Triticum↗
PubMed2026

Flux rewiring enables native D-glucosamine production in Escherichia coli.

D-Glucosamine is an industrially important amino sugar used in pharmaceuticals, nutraceuticals, and functional materials, yet its production remains dominated by chemical extraction from chitinous biomass, raising sustainability and allergen concerns. Escherichia coli natively synthesizes D-glucosamine directly from D-glucose through endogenous metabolism, revealing an underutilized amino sugar biosynthetic capability. Building on this native pathway, D-glucosamine production was enhanced through targeted genetic modifications and systematic optimization of nitrogen metabolism and cultivation conditions, reaching 9.2 g L-1 under shake-flask conditions. This work extends a phosphorylation-dephosphorylation strategy previously developed for neutral rare sugars to amino sugar biosynthesis, demonstrating the broader applicability of this metabolic design principle. Phosphatase identity emerged as a key control point for product formation: YbiV was the most effective phosphatase for selective D-glucosamine production, whereas alternative phosphatases redirected flux toward D-sedoheptulose. This enzyme-dependent flux partitioning further enabled tunable co-production of D-glucosamine and D-sedoheptulose. Native amino sugar biosynthesis in E. coli provides a controllable framework for producing chemically distinct sugars through endogenous metabolism and establishes a generalizable strategy for engineering amino sugar and other nitrogen-containing metabolite biosynthesis.

Escherichia coli↗
PubMed1979

Investigation and simplification of the sweep co-distillation cleanup of pesticide residues in animal fats.

The sweep co-distillation technique of Storherr et al. was investigated and simplified. Six organochlorine pesticides in animal fats were cleaned up under various distillation conditions as follows: No solvent was used, or solvent injection rates were 1 mL/min or 2 mL/3 min. Distillation tubes of 6.7 and 9.0 mm id diameter were compared. Distillation temperatures were varied from 150 to 300 degrees C. The complex condenser of Storherr et al. was compared with a simpler pipet condenser. A U-tube condenser which allows direct introduction onto a Florisil column for secondary cleanup was evaluated. The following modifications to the sweep co-distillation technique resulted: no solvent introduction, distillation temperature 230 degrees C, nitrogen flow rate 600 mL/min, 6.7 mm id distillation tubes with simplified packing, and incorporation of the U-tube condenser. The new technique gave recoveries comparable to those of Storherr et al., but it is faster than most bisolvent partition methods and no large volumes of solvent are required.

Animals↗
PubMed2026

Nitrogen sources and concentrations shape algal odor compounds: Key drivers of β-cyclocitral and β-ionone in water bodies of the lower Yangtze River.

Taste and odor (T&O) compounds derived from cyanobacterial blooms pose escalating threats to freshwater security worldwide, yet the drivers of specific T&O metabolites remain poorly constrained. Here, we investigated the dual effects of nitrogen (N) sources and concentrations on the production of β-cyclocitral and β-ionone, two algal-derived T&O compounds, through integrated field surveys (54 sites across lakes and rivers) in the eutrophic lower Yangtze River, China, and laboratory cultivation of typical cyanobacteria (Microcystis aeruginosa and Pseudanabaena cinerea). Our field data revealed that the concentrations of β-cyclocitral and β-ionone in lakes and rivers were not significantly different, but increased with the trophic level index. Redundancy analysis and Mantel analysis showed that Microcystis and Pseudanabaena were potentially dominant contributors to β-cyclocitral and β-ionone in the water column. Structural equation modeling and variation partitioning analysis showed that enhanced nitrate (NO3--N) significantly promoted the production of these compounds. Laboratory experiments demonstrated that inorganic N (NaNO₃) maximized total T&O yields by promoting algal biomass, whereas organic N (urea and glutamic acid) elevated the T&O production per unit biomass by 1.5- to 9.5-fold. Notably, Pseudanabaena exhibited a 2.3-fold higher β-ionone yield than Microcystis, with greater sensitivity to N concentrations. Our study highlights the critical role of nitrogen pollution, both source and concentration, in the production of T&O compounds by phytoplankton and provides reference data for managing T&O issues in rivers and shallow lakes.

Norisoprenoids↗
PubMed1979

Circulatory homeostasis in rats after bile duct ligation.

The bile duct was ligated in rats, and their tolerance against a small blood loss was evaluated 7 days later. A 10% blood loss precipitated a large and sometimes fatal reduction in arterial blood pressure, while no reduction was seen in shamoperated rats. The plasma and erythrocytes were labelled by isotopes and the animals were rapidly frozen in liquid nitrogen. The splanchnic and pulmonary blood volumes were estimated from the isotope content in blood and tissue. These vascular beds will normally reduce their blood volumes during a blood loss and thus serve as vascular depots. In the bile duct occluded animals, the partition of blood is changed. More blood is to be found in the splanchnic vessels, and the depot function of the lung vessels is partly used for compensation. When these rats were bled, their liver blood volumes were not reduced, and only a small further reduction took place in the lung vessels. It is concluded that rats with bile duct occlusion will suffer considerably from small blood losses. This may be due to a lacking depot function of the splanchnic vessels.

Animals↗
PubMed1979

The effects of some hydrophobic gases on the pulmonary surfactant system.

1. Decompression from exposures to raised ambient pressure of sulphur hexafluoride, carbon tetrafluoride, hexafluoro-ethane and nitrous oxide results in the formation of dense foam and pulmonary oedema. 2. The degree of pulmonary oedema produced is dependent on the exposure pressure, although the exposure time required is short in comparison to tissue saturation times. 3. The effect is not prevented by atropine, ephedrine or hydrocortisone. 4. The effect is also produced in vitro by saturated solutions of halothane, chloroform and ether. 5. It is suggested that the mechanism of action is physical with physico-chemical factor involved being a differential partition of these gases within the surfactant: membrane complex.

Animals↗
PubMed2026

Building biofilms for saline hydrogenotrophic denitrification from contrasting origins: Convergent acclimation, divergent performance.

Hydrogenotrophic denitrification is promising for deep nitrogen removal from saline, low-C/N wastewaters, but rapid establishment of stable biofilms at high salinity remains challenging. Here, two saline-adapted inocula from two representative, functionally contrasting habitats-a functionally-diversified inoculum from mangrove sediment and a functionally-focused inoculum from seabed sediment-were acclimated in parallel H2-based membrane biofilm reactors at constant 3.5% salinity. The Diverse-derived biofilm required 80 d to reach steady state and achieved only partial denitrification with 61.1% nitrate removal and considerable nitrite accumulation. In contrast, the Focus-derived biofilm rapidly established complete denitrification within ∼40 d, which was maintained for >50 d, with effluent NOx- below 1 mg-N·L-1 and 98.7% nitrate removal. Microbiome analyses showed that identical operation promoted convergence in community structure and enriched similar community-level functional potentials. However, genome-resolved analysis revealed distinct source-dependent functional organization among dominant microbial populations. Complete denitrifiers co-encoding denitrifying, hydrogenotrophic, and autotrophic functions were preferentially enriched in the Focus-derived biofilm, whereas these functions remained partitioned among different dominant populations in the Diverse-derived biofilm, coinciding with less complete denitrification. These findings indicate that saline hydrogenotrophic denitrification performance depends not only on which functions are enriched at the community level, but also on how key functions become organized among microbial populations, providing a previously overlooked criterion for inoculum selection in saline biological nitrogen control.

Complete denitrification↗
PubMed2026

Cross-domain cooperation drives nutrient acquisition and metabolism in the bark beetle holobiont.

Microbial symbiosis underpins host adaptation, yet mechanisms of metabolic integration in holobionts remain unclear. Using metatranscriptomics, genomics, and metabolic assays, we investigated gut microbiome interactions in the European spruce bark beetle (Ips typographus). We observed metabolic complementarity among symbionts and host, forming cross-domain networks that support nutrient acquisition. Nitrogen recycling revealed strong interdependence: no single partner possessed a complete uric acid degradation pathway, but combined evidence supports a distributed pathway spanning beetle, Bacteria, and fungi. Additionally, bacterial nitrate reduction to ammonia indicates a potential nitrogen influx, making otherwise inaccessible inorganic nitrogen available to the host. Shaped by microbial interactions, symbionts also likely supply specific amino acids, while vitamin metabolism showed cross-domain co-metabolism, with Bacteria as main producers of B vitamins, while host and fungi modulated interconversion. Carbohydrate degradation was highly partitioned; bacteria target xylan and pectin, while fungi contribute to glucan breakdown. Crucially, our data provide indirect evidence that the beetle may contribute to complete cellulose degradation, highlighting an underappreciated host role in lignocellulose processing. In terms of enzymatic functional diversity, the bacteriome emerged as the most important microbiome component-an observation that contrasts with the traditional focus on fungi and underscores the need to consider bacterial contributions in insect symbioses. Despite life-stage variation, core metabolic functions remained stable. Overall, metabolic interdependence, rather than microbial composition alone, structures holobiont function. These results highlight functional redundancy and ecological resilience, emphasizing the importance of microbial cooperation and host-microbe metabolic evolution.

Bark beetle↗
PubMed2026

Metabolic niche differentiation and napA evolution stabilize partial denitrification in wastewater ecosystems.

Although partial denitrification (PD) is increasingly applied as a nitrite-supplying strategy for anammox-based nitrogen removal, the ecological distribution, metabolic specialization, and genomic determinants of stable nitrite accumulation remain poorly understood at the ecosystem scale. Here, we reconstructed 516 high-quality metagenome-assembled genomes (MAGs) using high-depth metagenomic sequencing of 107 wastewater treatment plants and classified denitrifiers according to their nitrite production or consumption capacities. Of these genomes, 23% (120 MAGs) were classified as partial denitrifiers, 41% (211 MAGs) as complete denitrifiers, and 36% (185 MAGs) as nitrite-reducing denitrifiers, revealing pronounced functional partitioning rather than dominance by complete denitrification pathways. Comparative genomics showed that partial denitrifiers possess metabolic architectures favoring rapid carbon oxidation and NADH generation while exhibiting constrained NADPH production and biosynthetic investment, thereby promoting nitrate-to-nitrite conversion but limiting subsequent nitrite reduction. Nitrite accumulation does not result from incomplete denitrification pathways but from metabolic niche differentiation. These metabolic trade-offs were further associated with the evolutionary divergence of the periplasmic nitrate reductase gene, napA, which displayed distinct sequence characteristics and genomic contexts between partial and complete denitrifiers. Integration of carbohydrate-active enzyme repertoires further revealed metabolic complementarity between partial denitrifiers and anammox bacteria, supporting efficient carbon handoff without direct substrate competition. From an engineering perspective, operating conditions that impose moderate electron limitation, such as low or fluctuating C/N ratios and intermittent carbon feeding, may selectively enrich partial denitrifiers and enhance a stable nitrite supply for PD-anammox systems. Together, these findings identify PD as a predictable ecological state shaped by genome-encoded metabolic specialization and provide a mechanistic basis for designing robust, low-carbon nitrogen-removal processes.

Anammox↗
PubMed2026

Abundance-transcription decoupling reveals functional partitioning in bioelectrochemical denitrification biofilms.

Bioelectrochemical denitrification (BED) is often attributed to electroactive microorganisms that access electrode-derived electrons, yet the relative functional contribution of electroactive taxa and denitrifying populations within complex BED biofilms remain unclear. Here, we integrated reactor measurements with genome-resolved metagenomics and metatranscriptomics to examine microbial community structure, functional potential, and gene transcription across contrasting BED operational regimes differing in dissolved oxygen (DO), hydraulic retention time (HRT)/loading, and poised potential. Nitrate removal exceeded 90% across all tested conditions, but nitrogen intermediate accumulation, current generation, and theoretical electron balance differed substantially. Electroactive taxa such as Geobacter dominated (>80% abundance) under longer HRT and stronger poised potential, but contributed minimally to the transcription of canonical denitrification genes. Weaker cathodic potential enriched transcriptionally active denitrifying taxa such as Stutzerimonas, Acidovorax, and MR-S7, while oxygen exposure induced redox-stress responses and reshaped nitrogen metabolism beyond being a competing electron acceptor. Together, these results reveal a decoupling between taxonomic abundance, genomic functional potential, and transcriptional contribution in BED biofilms, indicating that nitrate-removal performance cannot be inferred from current generation or electroactive-taxon abundance alone.

Bioelectrochemical system↗