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1.
J Environ Manage ; 362: 121293, 2024 Jun 03.
Article in English | MEDLINE | ID: mdl-38833923

ABSTRACT

Soil acidification induced by reactive nitrogen (N) inputs is a major environmental issue in grasslands, as it lowers the acid neutralizing capacity (ANC). The specific impacts of different N compound forms on ANC remain unclear. Grassland management practices like mowing and grazing can remove a considerable amount of soil N and other nutrients, potentially mitigating soil acidification by removing N from the ecosystem or aggravating it by removing base cations. However, empirical evidence regarding the joint effects of adding different forms of N compounds and mowing on ANC changes in different-sized soil aggregates is still lacking. This study aimed to address this knowledge gap by examining the effects of three N compounds (urea, ammonium nitrate, and ammonium sulfate) combined with mowing (mown vs. unmown) on soil ANC in different soil aggregate sizes (>2000 µm, 250-2000 µm, and <250 µm) through a 6-year field experiment in Inner Mongolia grasslands. We found that the average decline in soil ANC caused by ammonium sulfate (AS) addition (-78.9%) was much greater than that by urea (-25.0%) and ammonium nitrate (AN) (-52.1%) as compared to control. This decline was attributed to increased proton (H+) release from nitrification and the leaching of exchangeable Ca2+ and Mg2+. Mowing aggravated the adverse effects of urea and AN on ANC, primarily due to the reduction in soil organic matter (SOM) contents and the removal of exchangeable Ca2+, K+, and Na + via plant biomass harvest. This pattern was consistent across all aggregate fractions. The lack of variation in soil ANC among different soil aggregate fractions is likely due to the contrasting trend in the distribution of exchangeable Ca2+ and Mg2+. Specifically, the concentration of exchangeable Ca2+ increased with increasing aggregate size, while the opposite was true for that of exchangeable Mg2+. These findings underscore the importance of considering the forms of N compounds when assessing the declines of ANC induced by N inputs, which also calls for an urgent need to reduce N emissions to ensure the sustainable development of the meadow ecosystems.

2.
Ying Yong Sheng Tai Xue Bao ; 35(1): 55-61, 2024 Jan.
Article in Chinese | MEDLINE | ID: mdl-38511440

ABSTRACT

Improving soil fertility is one of the key approaches for ecological restoration of the wind-sand area in northwest Liaoning Province. Taking wind-sand area in northwest Liaoning Province as test object, we conducted a fertilization experiment with treatments of inorganic fertilizer (nitrogen, phosphorus and potassium fertilizers), organic fertilizer, combined application of organic and inorganic fertilizers, and organic fertilizer combined with a biologically organic matrix (γ-polyglutamic acid), and no fertilizer as control. We measured soil organic matter content and extractable cations concentrations, vegetation coverage, and biomass under different fertilization treatments and determine the suitable fertilization mode. The results showed that compared to the control, inorganic fertilizer rapidly increased vegetation coverage and biomass, but high levels of inorganic fertilizer (150 kg N·hm-2) led to soil acidification and Ca2+ leaching. Organic fertilizer increased soil organic matter content, exchangeable K+, Ca2+, and Mg2+ contents, as well as coverage and biomass vegetation, especially combined with γ-polyglutamic acid. Overall, the combination of low levels of inorganic fertilizer (50 kg N·hm-2) and moderate levels of organic fertilizer (30000 kg·hm-2) was the best fertilization practice for the rapid and stable restoration of grassland in wind-sand area. Moreover, the extra addition of γ-polyglutamic acid (60 kg·hm-2)could effectively improve soil fertility.


Subject(s)
Agriculture , Soil , Agriculture/methods , Fertilizers , Sand , Grassland , Polyglutamic Acid , China , Nitrogen/analysis , Fertilization
3.
Aesthet Surg J ; 44(2): 216-225, 2024 Jan 16.
Article in English | MEDLINE | ID: mdl-37368877

ABSTRACT

BACKGROUND: Fat grafting is an effective procedure for breast augmentation, but the variations in this technique result in unpredictable fat retention. Therefore, animal models are needed to simulate the operation and the optimal layer for fat retention. OBJECTIVES: An autologous fat grafting murine model for breast augmentation was built to detect a new layer for fat grafting in the chest. METHODS: The left side of the female rat inguinal fat flap was harvested, dissected into small pieces, and autotransplanted into 3 different layers of the breast. Retention rate and hematoxylin and eosin (H&E) staining were measured at 1, 4, 8 12, and 16 weeks. Immunofluorescence staining was utilized to detect adipocytes and endothelial cells, and immunohistochemistry was conducted to evaluate the expression of integrins ß1 and α6. RESULTS: The volume of fat grafts slightly grew in the intramuscular and submuscular layers at Week 4. Retention rates in the subcutaneous layer and submuscular layer were significantly higher than the intramuscular layer at Week 16. H&E staining showed that oil cysts existed in the subcutaneous layer throughout the 16 weeks. At the terminal time point, well-vascularized mature adipose structures were observed in intramuscular and submuscular layers, with smaller adipocytes in intramuscular layers. Immunohistochemistry analysis showed that integrin ß1 was identically expressed in every adipocyte in all the layers, whereas integrin α6 selectively expressed in bigger adipocytes in the intramuscular layer. The expression intensities of integrin ß1 and α6 were significantly higher in the intramuscular layer than in the subcutaneous and submuscular layers. CONCLUSIONS: The angiogenic and moderate mechanical environment makes the submuscular layer the optimal layer for fat retention.


Subject(s)
Integrin beta1 , Mammaplasty , Mice , Rats , Female , Animals , Disease Models, Animal , Endothelial Cells , Mammaplasty/methods , Transplantation, Autologous/methods , Adipose Tissue/transplantation
5.
Anim Biotechnol ; 35(1): 2282090, 2024 Nov.
Article in English | MEDLINE | ID: mdl-38006572

ABSTRACT

At various stages of ovarian follicular development, more than 99% of follicles will be eliminated through a degenerative process called atresia. The regulatory mechanisms of atresia have been elucidated to some extent, involving hormones, growth factors, cytokines, and other factors. However, the stimuli initiating atresia in follicular granulosa cells remain unknown. In this study, we isolated the granulosa cells from porcine ovarian follicles (3-5 mm diameter) divided into healthy follicles (HFs) and early atretic follicles (EAFs). We applied high-throughput RNA sequencing to identify and compare differentially expressed genes (DEGs) between HFs and EAFs. A total of 31,694 genes were detected, of which 21,806 were co-expressed in six samples, and 243 genes (p < 0.05; FDR < 0.05) were differentially expressed (DEGs), including 123 downregulated and 120 upregulated in EAFs. GO analysis highlighted hormone metabolism, plasma membrane localization, and transporter activity. The pathway analysis indicated that 51 DEGs, involved in steroidogenesis, cell adhesion molecules, and TGF-beta signaling pathways, were highly related to atresia. Additionally, the interaction network of DEGs (p < 0.01; FDR < 0.05) using STRING highlighted LHR, ACACB, and CXCR4 as central nodes. In summary, this transcriptome analysis enriched our knowledge of the shifted mechanisms in granulosa cells during early atresia and provided novel perspectives into the atresia initiation.


Subject(s)
Ovarian Follicle , Transcriptome , Female , Animals , Swine/genetics , Granulosa Cells/metabolism , Gene Expression Profiling/veterinary , Apoptosis
6.
Lupus ; 33(1): 40-47, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38037717

ABSTRACT

BACKGROUND: Systemic Lupus Erythematosus patients (SLE) are at a higher risk of cardiovascular events than the general population. This study aimed to investigate the risk perception of cardiovascular disease (CVD) and to analyze its influence factors among Chinese SLE patients. METHODS: This was a cross-sectional study. Convenience sampling was used to select 201 patients with SLE who had attended the outpatient and inpatient departments of the Department of Rheumatology and Immunology at the First Affiliated Hospital of the University of Science and Technology of China from November 2022 to March 2023. The following were used in the study: the Chinese version of the Attitudes and Beliefs about Cardiovascular Disease Risk Questionnaire, the Social Support Rating Scale, the Connor-Davidson Resilience Scale, the General Self-Efficacy Scale, the Hospital Anxiety and Depression Scale, the Health Literacy Management Scale, and sociodemographic and disease-related data. RESULTS: The mean (standard deviation) risk perception score of CVD patients with SLE was 57.18 ± 13.02. A Pearson correlation analysis showed that CVD risk perceptions were positively correlated with health literacy (r = 0.152, p < .05) and depression (r = 0.277, p < .05), and negatively correlated with social support (r = -0.393, p < .05) and psychological resilience (r = -0.374, p < .05). A multiple linear regression analysis showed that body mass index (BMI), family history, health literacy, depression, social support, and psychological resilience were the main factors influencing CVD risk perceptions among Chinese SLE patients (p < .05). CONCLUSIONS: Body mass index, family history, health literacy, depression, social support, and psychological resilience influenced CVD risk perceptions among Chinese SLE patients. Healthcare workers should objectively and accurately assess the levels of CVD risk perception among SLE patients, identify the risk factors of CVD, adopt effective health risk communication strategies to help patients develop appropriate risk perceptions, and raise risk awareness to adopt active coping approaches to reduce risk.


Subject(s)
Cardiovascular Diseases , Lupus Erythematosus, Systemic , Humans , Cross-Sectional Studies , Cardiovascular Diseases/epidemiology , Cardiovascular Diseases/etiology , Lupus Erythematosus, Systemic/epidemiology , China/epidemiology , Risk Factors
9.
Nat Commun ; 14(1): 5731, 2023 09 18.
Article in English | MEDLINE | ID: mdl-37723164

ABSTRACT

The amyloid aggregation of α-synuclein (αS), related to Parkinson's disease, can be catalyzed by lipid membranes. Despite the importance of lipid surfaces, the 3D-structure and orientation of lipid-bound αS is still not known in detail. Here, we report interface-specific vibrational sum-frequency generation (VSFG) experiments that reveal how monomeric αS binds to an anionic lipid interface over a large range of αS-lipid ratios. To interpret the experimental data, we present a frame-selection method ("ViscaSelect") in which out-of-equilibrium molecular dynamics simulations are used to generate structural hypotheses that are compared to experimental amide-I spectra via excitonic spectral calculations. At low and physiological αS concentrations, we derive flat-lying helical structures as previously reported. However, at elevated and potentially disease-related concentrations, a transition to interface-protruding αS structures occurs. Such an upright conformation promotes lateral interactions between αS monomers and may explain how lipid membranes catalyze the formation of αS amyloids at elevated protein concentrations.


Subject(s)
Parkinson Disease , alpha-Synuclein , Humans , Amides , Amyloidogenic Proteins , Lipids
10.
Ying Yong Sheng Tai Xue Bao ; 34(7): 1834-1844, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37694467

ABSTRACT

Nitrogen deposition and summer precipitation in eastern Inner Mongolia are predicted to increase in recent decades. However, such increases in nitrogen inputs and precipitation may not be continuous under the future new patterns of global change, with the direction and magnitude of which may change or weaken. The legacy effects of nitrogen and water addition after cessation on ecosystems are still unclear. Based on a 13-year nitrogen and water addition experiment in temperate grassland of northern China, we examined the short-term (2 years) legacy effects of historical nitrogen and water addition on soil physicochemical properties and microbial properties after the cessation of nitrogen and water addition in the 14th year. The results showed that the positive effects of historical nitrogen addition on most of soil nutrient variables diminished after two years of cessation, including ammonium nitrogen, nitrate nitrogen, dissolved organic carbon and nitrogen, and Olsen-P concentrations. In contrast, there were legacy effects on soil microbial characteristics. For example, the historical nitrogen input of 15 g N·m-2·a-1 reduced microbial biomass carbon, respiration, and alkaline phosphomonoesterase activity by 73.3%, 81.9%, and 70.3% respectively. It implied that microbial parameters restored slowly in comparison with soil nutrients, showing a hysteresis effect. Results of Pearson's correlation and redundancy analysis showed that the legacy effects of historical nitrogen addition on microbial parameters could be attributed to the negative effects of nitrogen addition on soil pH. Historical water addition showed significant legacy effects on soil pH, ammonium nitrogen, dissolved organic carbon and nitrogen, respiration, and soil enzyme activities, which significantly interacted with historical nitrogen addition. These results are of great significance to predict the changes in grassland ecosystem functions and services under the local environmental improvement conditions, and to reveal the restoration mechanism of degraded grassland.


Subject(s)
Dissolved Organic Matter , Nitrogen , Ecosystem , Grassland , Carbon , Soil , Water
11.
Cell Mol Biol Lett ; 28(1): 75, 2023 Sep 28.
Article in English | MEDLINE | ID: mdl-37770821

ABSTRACT

Osteoarthritis (OA), a common joint disorder with articular cartilage degradation as the main pathological change, is the major source of pain and disability worldwide. Despite current treatments, the overall treatment outcome is unsatisfactory. Thus, patients with severe OA often require joint replacement surgery. In recent years, mesenchymal stem cells (MSCs) have emerged as a promising therapeutic option for preclinical and clinical palliation of OA. MSC-derived exosomes (MSC-Exos) carrying bioactive molecules of the parental cells, including non-coding RNAs (ncRNAs) and proteins, have demonstrated a significant impact on the modulation of various physiological behaviors of cells in the joint cavity, making them promising candidates for cell-free therapy for OA. This review provides a comprehensive overview of the biosynthesis and composition of MSC-Exos and their mechanisms of action in OA. We also discussed the potential of MSC-Exos as a therapeutic tool for modulating intercellular communication in OA. Additionally, we explored bioengineering approaches to enhance MSC-Exos' therapeutic potential, which may help to overcome challenges and achieve clinically meaningful OA therapies.


Subject(s)
Cartilage, Articular , Exosomes , Mesenchymal Stem Cells , Osteoarthritis , Humans , Exosomes/metabolism , Chondrocytes/metabolism , Osteoarthritis/therapy , Osteoarthritis/metabolism , Cartilage, Articular/metabolism , Mesenchymal Stem Cells/metabolism
12.
Nutrients ; 15(14)2023 Jul 14.
Article in English | MEDLINE | ID: mdl-37513557

ABSTRACT

The triglyceride-glucose (TyG) index, triglyceride-to-high-density-lipoprotein-cholesterol (TG/HDL-C) ratio, metabolic score for insulin resistance (METS-IR) and TyG with body mass index (TyG-BMI) have been proposed as indicators of insulin resistance (IR). This study aimed to explore the association between these IR surrogates and their longitudinal variation with the development of hyperuricemia in a middle-aged and older Chinese population. Data from the China Health and Retirement Longitudinal Study (CHARLS) was used to identify 5269 participants aged ≥45 years. Logistic regression was used to assess the effect of IR surrogates and their variations on the risk of hyperuricemia. After four years of follow-up, 517 (9.81%) participants developed incident hyperuricemia. Increased baseline values of TyG, TG/HDL, METS-IR, and TyG-BMI were all significantly associated with higher risks of hyperuricemia. Compared to individuals with maintained low levels of IR surrogates, those with low-to-high and maintained high variation patterns had a significantly higher risk of hyperuricemia. These four IR surrogates have comparable predictive ability for hyperuricemia. This study provides evidence of the associations between IR and hyperuricemia. Early intervention among middle-aged and elderly Chinese individuals with high IR levels may effectively reduce the burden of hyperuricemia.


Subject(s)
Hyperuricemia , Insulin Resistance , Middle Aged , Aged , Humans , Hyperuricemia/epidemiology , Longitudinal Studies , Cohort Studies , Blood Glucose/metabolism , Biomarkers , Glucose , Triglycerides , Cholesterol, HDL
13.
Immunology ; 2023 May 19.
Article in English | MEDLINE | ID: mdl-37204242

ABSTRACT

Systemic immune activation and excessive inflammatory response, induced by intestinal barrier damage, are the major characteristics of inflammatory bowel disease (IBD). Excessive apoptotic cell accumulation leads to the production of a large number of inflammatory factors, further aggravating IBD development. Gene set enrichment analysis data showed that the homodimeric erythropoietin receptor (EPOR) was highly expressed in the whole blood of patients with IBD. EPOR is specifically expressed in intestinal macrophages. However, the role of EPOR in IBD development is unclear. In this study, we found that EPOR activation significantly alleviated colitis in mice. Furthermore, in vitro, EPOR activation in bone marrow-derived macrophage (BMDMs) promoted microtubule-associated protein 1 light chain 3B (LC3B) activation and mediated the clearance of apoptotic cells. Moreover, our data showed that EPOR activation facilitated the expression of phagocytosis- and tissue-repair-related factors. Our findings suggest that EPOR activation in macrophages promotes apoptotic cell clearance, probably via LC3B-associated phagocytosis (LAP), providing a new mechanism for understanding pathological progression and a novel potential therapeutic target for colitis.

14.
J Asian Nat Prod Res ; 25(12): 1217-1222, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37163366

ABSTRACT

A new abietane diterpenoid, 1ß, 11-epoxyabieta-12-hydroxy-8, 11, 13-triene-7-one (1), along with three known compounds (2-4), was isolated from Lycopodium complanatum. Their structures were confirmed by the analysis of 1D, 2D NMR and HRESIMS data, and comparison with previous spectral data. All compounds were tested for inhibitory activities against A549, HepG2 and MCF-7 tumor cell lines. [Figure: see text].


Subject(s)
Antineoplastic Agents, Phytogenic , Lycopodium , Humans , Abietanes/pharmacology , Abietanes/chemistry , Molecular Structure , Lycopodium/chemistry , Cell Line, Tumor , MCF-7 Cells , Antineoplastic Agents, Phytogenic/pharmacology , Antineoplastic Agents, Phytogenic/chemistry
15.
J Hazard Mater ; 448: 130949, 2023 Apr 15.
Article in English | MEDLINE | ID: mdl-36860077

ABSTRACT

Colloids are wide-spread in natural waters and colloid-facilitated transport via adsorption was established as the most important mechanism for the mobilization of aqueous contaminants. This study reports another possible, but reasonable, role of colloids for the contaminants driven by redox reactions. Under the same conditions (pH 6.0, 0.3 ml 30% H2O2, and 25 °C), the degradation efficiencies of methylene blue (MB) at 240 min over Fe colloid, Fe ion, Fe oxide and Fe(OH)3 were 95.38%, 42.66%, 4.42% and 9.40%. We suggested that, Fe colloid can promote the H2O2 based in-situ chemical oxidation process (ISCO) compared with other iron species such as Fe(Ⅲ) ion, Fe oxide and Fe(OH)3 in natural water. Furthermore, the MB removal via adsorption by Fe colloid was only 1.74% at 240 min. Hence, the occurrence, behavior and fate of MB in Fe colloid containing natural water system mainly depends on the reduction-oxidation rather than adsorption-desorption process. Based on the mass balance of colloidal iron species and characterization of iron configurations distribution, Fe oligomers were the active and dominant components for Fe colloid-driven enhanced H2O2 activation among three types of Fe species. The quick and steady conversion of Fe(III) to Fe(II) was proven to be reason why Fe colloid can efficiently react with H2O2 to produce hydroxyl radicals.

16.
Exp Gerontol ; 172: 112077, 2023 02.
Article in English | MEDLINE | ID: mdl-36587798

ABSTRACT

The Geriatric Depression Scale with 30 items (GDS-30) and with 15 items (GDS-15) are both valid tools for assessing depression in older adults, but their absolute values are not directly comparable. Here, we used a dataset (n = 431) with GDS-30 scores from a project concerning fall-risk assessment in older adults (FARAO) to develop and validate a formula which can be used to convert GDS-15 scores into GDS-30 scores. We found that the GDS-15 score cannot simply be multiplied by 2 to obtain the GDS-30 scores and that estimations of GDS-30 from GDS-15 are not affected by age, sex and MMSE. Therefore, the optimal formula to estimate the GDS-30 score from the GDS-15 score was: GDS-30_estimated = 1.57 + 1.95 × GDS-15. This formula yielded an estimate of GDS-30 with an explained variance of 79 %, compared to 63 % when GDS-15 was simply multiplied by 2. Researchers that have used the GDS-15 and want to compare their outcomes to other studies that reported only the GDS-30 are advised to use this formula.


Subject(s)
Depression , Geriatric Assessment , Humans , Aged , Depression/diagnosis , Psychiatric Status Rating Scales
17.
Int J Biol Macromol ; 227: 222-230, 2023 Feb 01.
Article in English | MEDLINE | ID: mdl-36509202

ABSTRACT

This research focused on the characteristics of amorphous aggregates derived from soy protein (SPAA), and their effects on the structural, physicochemical, and digestive properties of potato starch (PS). The SPAA induced by different heating temperatures at pH 7.0 formed an inhomogeneous spherical structure. The presence of SPAA could improve the degree of short-range order of starch, increase thermal stability, reduce pasting viscosity and breakdown, and setback viscosity values of PS. For the PS complexed with SPAAs under simulated cooking conditions, the fraction of digested starch at 300 min (C300) decreased by 6-14 %, and rapid digestible starch content (RDS) decreased by 18-25 %, while the slowly digestible starch (SDS) and resistant starch (RS) increased by 0.4-3 % and 15-23 %, respectively. The SPAA at higher temperature treatment (SPAA130) reduced digestive rate coefficient (k) values more significantly than SPAA at a lower temperature (SPAA70, SPAA90, SPAA110). And the SPAA had no inhibitory effect on α-amylase. The results of this study would significantly contribute to expanding the theoretical information about protein regulation in starch digestion and promoting the development of healthy foods with digestion-resistant properties.


Subject(s)
Hot Temperature , Solanum tuberosum , Solanum tuberosum/chemistry , Soybean Proteins , Digestion , Starch/chemistry , Viscosity
18.
Int J Mol Sci ; 23(23)2022 Dec 02.
Article in English | MEDLINE | ID: mdl-36499522

ABSTRACT

Circular RNAs (circRNAs) are an abundant class of endogenous non-coding RNAs (ncRNAs) generated from exonic, intronic, or untranslated regions of protein-coding genes or intergenic regions. The diverse, stable, and specific expression patterns of circRNAs and their possible functions through cis/trans regulation and protein-coding mechanisms make circRNA a research hotspot in various biological and pathological processes. It also shows practical value as biomarkers, diagnostic indicators, and therapeutic targets. This review summarized the characteristics, classification, biogenesis and elimination, detection and confirmation, and functions of circRNAs. We focused on research advances circRNAs in the mammalian ovary under conditions including ovarian cancer, polycystic ovarian syndrome (PCOS), and maternal aging, as well as during reproductive status, including ovarian follicle development and atresia. The roles of circRNAs in high reproductive traits in domestic animals were also summarized. Finally, we outlined some obstructive factors and prospects to work with circRNA, aiming to provide insights into the functional research interests of circRNAs in the reproduction and gynecology areas.


Subject(s)
Polycystic Ovary Syndrome , RNA, Circular , Humans , Animals , Female , RNA, Circular/genetics , RNA, Circular/metabolism , Polycystic Ovary Syndrome/genetics , Introns , Exons , Mammals/metabolism
19.
Biology (Basel) ; 11(11)2022 Nov 08.
Article in English | MEDLINE | ID: mdl-36358332

ABSTRACT

The transcriptional initiation of genes is closely bound to the functions of cis-regulatory elements, including promoters, typical enhancers (TEs), and recently-identified super-enhancers (SEs). In this study, we identified these cis-regulatory elements in the livers of two Chinese (Meishan and Enshi Black) and two Western (Duroc and Large White) pig breeds using ChIP-seq data, then explored their similarities and differences. In addition, we analyzed the conservation of SEs among different tissues and species (pig, human, and mouse). We observed that SEs were more significantly enriched by transcriptional initiation regions, TF binding sites, and SNPs than other cis-elements. Western breeds included fewer SEs in number, while more growth-related QTLs were associated with these SEs. Additionally, the SEs were highly tissue-specific, and were conserved in the liver among humans, pigs, and mice. We concluded that intense selection could concentrate functional SEs; thus, SEs could be applied as effective detection regions in genomic selection breeding.

20.
Ying Yong Sheng Tai Xue Bao ; 33(8): 2161-2170, 2022 Aug.
Article in Chinese | MEDLINE | ID: mdl-36043823

ABSTRACT

Nitrogen is the most limiting nutrient for ecosystems. The natural abundance of δ15N (15N/14N) can efficiently indicate ecosystem nitrogen cycling processes. We investigated the interannual variations in natural abundance of δ15N in soil-plant system and soil net nitrogen mineralization in a meadow steppe of Inner Mongolia. Results across the four sampling years (2017-2020) showed that the content of soil NO3--N (9.83-14.79 mg·kg-1) was significantly higher than that of NH4+-N (3.92-5.00 mg·kg-1) and that δ15N value of soil NH4+ (13.3‰-18.3‰) was significantly higher than that of NO3-(3.76‰-6.14‰). The δ15N value of soil NO3- was negatively correlated with soil NO3- content. The δ15N value of soil NH4+ was relatively higher in the dry years, while the δ15N value of soil NO3- significantly decreased in the wetter and drier years. Soil net mineralization and ammonification rates were significantly higher in the dry years than that of the wet years, while soil nitrification rates showed no correlation with annual precipitation. The δ15N values of plants were not related to that of soils, but nega-tively correlated with plant nitrogen content. Both δ15N values and nitrogen contents were significantly and positively correlated between the leguminous and non-leguminous plants, suggesting that legume could facilitate nitrogen uptake of non-leguminous plants. These results could provide supporting data for nitrogen cycling and their responses to changes in precipitation in grassland soil-plant systems.


Subject(s)
Ecosystem , Soil , China , Grassland , Nitrogen/analysis , Nitrogen Isotopes/analysis , Plants
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