Chemical Method for Nitrogen Isotopic Analysis of Ammonium at Natural Abundance

We report a new chemical method to determine the ¹⁵N natural abundance (δ¹⁵N) for ammonium (NH₄⁺) in freshwater (e.g., precipitation) and soil KCl extract. This method is based on the isotopic analysis of nitrous oxide (N₂O). Ammonium is initially oxidized to nitrite (NO₂^–) by hypobromite (BrO^–) using previously established procedures. NO₂^– is then quantitatively converted into N₂O by hydroxylamine (NH₂OH) under strongly acid conditions. The produced N₂O is analyzed by a commercially available purge and cryogenic trap system coupled to an isotope ratio mass spectrometer (PT-IRMS). On the basis of a typical analysis size of 4 mL, the standard deviation of δ¹⁵N measurements is less than 0.3‰ and often better than 0.1‰ (3 to 5 replicates). Compared to previous methods, the technique here has several advantages and the potential to be used as a routine method for ¹⁵N/¹⁴N analysis of NH₄⁺: (1) substantially simplified preparation procedures and reduced preparation time particularly compared to the methods in which diffusion or distillation is involved since all reactions occur in the same vial and separation of NH₄⁺ from solution is not required; (2) more suitability for low volume samples including those with low N concentration, having a blank size of 0.6 to 2 nmol; (3) elimination of the use of extremely toxic reagents (e.g., HN₃) and/or the use of specialized denitrifying bacterial cultures which may be impractical for many laboratories

Novel immune cross-talk between inflammatory bowel disease and IgA nephropathy

The mechanisms underlying the complex correlation between immunoglobulin A nephropathy (IgAN) and inflammatory bowel disease (IBD) remain unclear. This study aimed to identify the optimal cross-talk genes, potential pathways, and mutual immune-infiltrating microenvironments between IBD and IgAN to elucidate the linkage between patients with IBD and IgAN. The IgAN and IBD datasets were obtained from the Gene Expression Omnibus (GEO). Three algorithms, CIBERSORTx, ssGSEA, and xCell, were used to evaluate the similarities in the infiltrating microenvironment between the two diseases. Weighted gene co-expression network analysis (WGCNA) was implemented in the IBD dataset to identify the major immune infiltration modules, and the Boruta algorithm, RFE algorithm, and LASSO regression were applied to filter the cross-talk genes. Next, multiple machine learning models were applied to confirm the optimal cross-talk genes. Finally, the relevant findings were validated using histology and immunohistochemistry analysis of IBD mice. Immune infiltration analysis showed no significant differences between IBD and IgAN samples in most immune cells. The three algorithms identified 10 diagnostic genes, MAPK3, NFKB1, FDX1, EPHX2, SYNPO, KDF1, METTL7A, RIDA, HSDL2, and RIPK2; FDX1 and NFKB1 were enhanced in the kidney of IBD mice. Kyoto Encyclopedia of Genes and Genomes analysis showed 15 mutual pathways between the two diseases, with lipid metabolism playing a vital role in the cross-talk. Our findings offer insights into the shared immune mechanisms of IgAN and IBD. These common pathways, diagnostic cross-talk genes, and cell-mediated abnormal immunity may inform further experimental studies.</p

Characteristics of all subjects.

<p>The data are presented as mean±S.E.</p><p>*<i>P</i> < 0.05</p><p>***<i>P</i> < 0.001 versus normal healthy controls.</p><p>BMI: body mass index; HbA1c: hemoglobin A1c; TG: triglyceride; Cr: creatinine; BUN: blood urea nitrogen; ACR, albumin to creatinine ratio; H-CRP: high-sensitive C-reactive protein. ACEI: angiotensin-converting enzyme inhibitor; ARB: angiotensin Ⅱ receptor antagonist</p><p>Characteristics of all subjects.</p

mRNA levels of IL-6, IL-18, and TTP in urine and serum samples.

<p>Samples from urine (A and B) and serum (A and C) were analyzed by semi-quantitative RT-PCR and visualized by electrophoresis on acrylamide gels. Representative gels are shown in A; and quantification of the results of patients from each group (normal, n = 41; diabetic without proteinuria, n = 33; diabetic with microalbuminuria, n = 29; and diabetic with clinical proteinuria, n = 25) is shown in B and C. The data are presented as mean±S.E. *<i>P</i> < 0.05, **<i>P</i> < 0.01 compared with normal healthy controls, ^## P<0.01 compared with diabetic without proteinuria, and ^△△P<0.01 compared with diabetic with microalbuminuria.</p

Inverse relationship between serum TTP and IL-18 or IL-6.

<p>The correlation between serum TTP and IL-6 (A) or IL-18 (B) protein levels was determined by plotting the corresponding values for individual diabetic patients. A best fit line is drawn.</p

Protein contents of IL-6, IL-18, and TTP in urine and serum samples.

<p>Samples from urine (A) and serum (B) of patients from the normal (n = 41), diabetic without proteinuria (n = 33), diabetic with microalbuminuria (n = 29), and diabetic with clinical proteinuria (n = 25) groups were analyzed by ELISA. The data are presented as mean±S.E. *<i>P</i>< 0.05, **<i>P</i> < 0.01 compared with normal healthy controls, ^## P<0.01 compared with diabetic without proteinuria, and ^△△P<0.01 compared with diabetic with microalbuminuria.</p

Characteristics of all subjects.

<p>The data are presented as mean±S.E.</p><p>*<i>P</i> < 0.05</p><p>***<i>P</i> < 0.001 versus normal healthy controls.</p><p>BMI: body mass index; HbA1c: hemoglobin A1c; TG: triglyceride; Cr: creatinine; BUN: blood urea nitrogen; ACR, albumin to creatinine ratio; H-CRP: high-sensitive C-reactive protein. ACEI: angiotensin-converting enzyme inhibitor; ARB: angiotensin Ⅱ receptor antagonist</p><p>Characteristics of all subjects.</p

DataSheet_1_Temperature explains intraspecific functional trait variation in Phragmites australis more effectively than soil properties.docx

Common reed (Phragmites australis) is a widespread grass species that exhibits a high degree of intraspecific variation for functional traits along environmental gradients. However, the mechanisms underlying intraspecific variation and adaptation strategies in response to environmental gradients on a regional scale remain poorly understood. In this study, we measured leaf, stem, and root traits of common reed in the lakeshore wetlands of the arid and semi-arid regions of the Inner Mongolia Plateau aiming to reveal the regional-scale variation for functional traits in this species, and the corresponding potentially influencing factors. Additionally, we aimed to reveal the ecological adaptation strategies of common reed in different regions using the plant economics spectrum (PES) theory. The results showed that functional-trait variation followed significant latitudinal and longitudinal patterns. Furthermore, we found that these variations are primarily driven by temperature-mediated climatic differences, such as aridity, induced by geographical distance. In contrast, soil properties and the combined effects of climate and soil had relatively minor effects on such properties. In the case of common reed, the PES theory applies to the functional traits at the organ, as well as at the whole-plant level, and different ecological adaptation strategies across arid and semi-arid regions were confirmed. The extent of utilization and assimilation of resources by this species in arid regions was a conservative one, whereas in semi-arid regions, an acquisition strategy prevailed. This study provides new insights into intraspecific variations for functional traits in common reed on a regional scale, the driving factors involved, and the ecological adaptation strategies used by the species. Moreover, it provided a theoretical foundation for wetland biodiversity conservation and ecological restoration.</p

Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from ¹⁵N‑Stable Isotope in Size-Resolved Aerosol Ammonium

The reduction of ammonia (NH₃) emissions is urgently needed due to its role in aerosol nucleation and growth causing haze formation during its conversion into ammonium (NH₄⁺). However, the relative contributions of individual NH₃ sources are unclear, and debate remains over whether agricultural emissions dominate atmospheric NH₃ in urban areas. Based on the chemical and isotopic measurements of size-resolved aerosols in urban Beijing, China, we find that the natural abundance of ¹⁵N (expressed using δ¹⁵N values) of NH₄⁺ in fine particles varies with the development of haze episodes, ranging from −37.1‰ to −21.7‰ during clean/dusty days (relative humidity: ∼ 40%), to −13.1‰ to +5.8‰ during hazy days (relative humidity: 70–90%). After accounting for the isotope exchange between NH₃ gas and aerosol NH₄⁺, the δ¹⁵N value of the initial NH₃ during hazy days is found to be −14.5‰ to −1.6‰, which indicates fossil fuel-based emissions. These emissions contribute 90% of the total NH₃ during hazy days in urban Beijing. This work demonstrates the analysis of δ¹⁵N values of aerosol NH₄⁺ to be a promising new tool for partitioning atmospheric NH₃ sources, providing policy makers with insights into NH₃ emissions and secondary aerosols for regulation in urban environments