Whole-soil-profile warming does not change microbial carbon use efficiency in surface and deep soils.

The paucity of investigations of carbon (C) dynamics through the soil profile with warming makes it challenging to evaluate the terrestrial C feedback to climate change. Soil microbes are important engines driving terrestrial biogeochemical cycles; their carbon use efficiency (CUE), defined as the proportion of metabolized organic C allocated to microbial biomass, is a key regulator controlling the fate of soil C. It has been theorized that microbial CUE should decline with warming; however, empirical evidence for this response is scarce, and data from deeper soils are particularly scarce. Here, based on soil samples from a whole-soil-profile warming experiment (0 to 1 m, +4 °C) and 18O tracing approach, we examined the vertical variation of microbial CUE and its response to ~3.3-y experimental warming in an alpine grassland on the Qinghai-Tibetan Plateau. Microbial CUE decreased with soil depth, a trend that was primarily controlled by soil C availability. However, warming had limited effects on microbial CUE regardless of soil depth. Similarly, warming had no significant effect on soil C availability, as characterized by extractable organic C, enzyme-based lignocellulose index, and lignin phenol-based ratios of vanillyls, syringyls, and cinnamyls. Collectively, our work suggests that short-term warming does not alter microbial CUE in either surface or deep soils, and emphasizes the regulatory role of soil C availability on microbial CUE.

F-actin/DRP1 axis-mediated mitochondrial fission promotes mitophagy in diabetic submandibular glands.

BACKGROUND: Diabetes is accompanied by a high prevalence of hyposalivation, causing severe damage to oral and systemic health. Mitochondrial dynamics play important roles in the pathogenesis of various diabetic complications; however, little is known about their roles in diabetic hyposalivation. MATERIALS AND METHODS: A diabetic mouse model and a high glucose (HG)-induced diabetic submandibular gland (SMG) cell model were employed. RESULTS: More mitochondria surrounded by autophagosomes and higher expression of mitophagy-related proteins were detected in the SMGs of diabetic mice and HG-treated SMG cells. In diabetic SMGs, dynamin-related protein 1 (DRP1) was upregulated, whereas mitofusin-2 was downregulated both in vivo and in vitro. Shortened mitochondria and impaired mitochondrial functions were observed in the HG group. A DRP1-specific inhibitor, mdivi-1, suppressed mitochondrial fission and mitophagy, as well as restored mitochondrial functions in the HG condition. Moreover, the interaction of F-actin and DRP1 was enhanced in the diabetic group. Inhibiting F-actin with cytochalasin D repaired the injured effects of HG on mitochondrial dynamics and functions. Conversely, the F-actin-polymerization-inducer jasplakinolide aggravated mitochondrial fission and dysfunction. CONCLUSIONS: F-actin contributes to HG-evoked mitochondrial fission by interacting with DRP1, which induces mitophagy and impairs mitochondrial function in SMG cells, ultimately damaging the SMG.

Temperature and Twist Sensor Based on the Sagnac Interferometer with Long-Period Grating in Polarization-Maintaining Fiber.

We utilized a CO2 laser to carve long-period fiber gratings (LPFGs) on polarization-maintaining fibers (PMFs) along the fast and slow axes. Based on the spectra of LPFGs written along two different directions, we found that when LPFG was written along the fast axis, the spectrum had lower insertion loss and fewer side lobes. We investigated the temperature and twist characteristics of the embedded structure of the LPFG and Sagnac loop and ultimately obtained a temperature sensitivity of -0.295 nm/°C and a twist sensitivity of 0.87 nm/(rad/m) for the LPFG. Compared to the single LPFG, the embedded structure of the LPFG and Sagnac loop demonstrates a significant improvement in temperature and twist sensitivities. Additionally, it also possesses the capability to discern the direction of the twist. The embedded structure displays numerous advantages, including easy fabrication, low cost, good robustness, a wide range, and high sensitivity. These features make it highly suitable for applications in structural health monitoring and other related fields.

A distinct sensitivity to the priming effect between labile and stable soil organic carbon.

Soil organic carbon (SOC) is a mixture of various carbon (C) compounds with different stability, which can be distinctly affected by the priming effect (PE). However, little is known about how the PE changes with SOC stability. We address this issue by combining results from two experiments and a metaanalysis. We found that the PE increased with the prolongation of soil preincubation, suggesting that higher PE occurred for more stable SOC than for labile SOC. This was further supported by the metaanalysis of 42 observations. There were significant negative relationships between the difference in PE (ΔPE) between labile and more stable SOC and their differences in SOC, microbial biomass C and soil C : N ratio, indicating that soil C availability exerts a vital control on ΔPE. We conclude that, compared with labile SOC, stable SOC can be more vulnerable to priming once microbes are provided with exogenous C substrates. This high vulnerability of stable SOC to priming warrants more attention in future studies on SOC cycling and global change.

Serum levels and significance of soluble B-cell maturation antigen in childhood-onset systemic lupus erythematosus with renal involvement.

OBJECTIVE: The aim of this study was to investigate serum levels of soluble B-cell maturation antigen (sBCMA) in childhood-onset systemic lupus erythematous (cSLE) patients with renal involvement, and to elucidate their association with clinical characteristics. METHODS: 116 cases of cSLE patients with renal involvement (84 females and 32 males; median age 11.6 (10.1, 12.9) years) hospitalized in Department of Pediatric Nephrology and Rheumatology, the First Affiliated Hospital, Sun Yat-sen University and 31 healthy controls (HCs) were enrolled. Serum concentrations of sBCMA were determined using enzyme-linked immunosorbent assay (ELISA). Clinical and laboratory information of cSLE patients were retrospectively analyzed. RESULTS: Serum sBCMA levels were significantly increased in primary cSLE when compared with treated cSLE patients and HCs, whereas there was no significant difference between treated cSLE patients and HCs. Patients with high disease activity displayed higher serum sBCMA levels compared with those with no or mild to moderate disease activity. Positive correlation was observed between serum sBCMA levels and systemic lupus erythematosus disease activity index-2K (SLEDAI-2K), antinuclear antibody titers, anti-double-stranded DNA titers, erythrocyte sedimentation rate, and immunoglobulin G levels, while sBCMA levels were negatively correlated with blood white blood cell count, hemoglobin, platelet count, complement C3 and C4 levels. Serum sBCMA levels decreased as disease ameliorated after treatments among 11 cases with follow-up examinations. CONCLUSIONS: In cSLE patients with renal involvement, serum sBCMA levels correlated significantly with disease activity, immunological, and hematological parameters, but not with renal parameters. Our results suggest the potential and significance of serum sBCMA as a biomarker in cSLE patients.

High-Sensitivity Temperature Sensor Based on Fiber Fabry-Pérot Interferometer with UV Glue-Filled Hollow Capillary Fiber.

Optical fiber Fabry-Pérot (FP) interferometer sensors have long been the focus of researchers in sensing applications because of their simple light path, low cost, compact size and convenient manufacturing methods. A miniature and highly sensitive optic fiber temperature sensor using an ultraviolet glue-filled FP cavity in a hollow capillary fiber is proposed. The sensor is fabricated by fusion splicing a single-mode fiber with a hollow capillary fiber, which is filled with ultraviolet glue to form a FP cavity. The sensor has a good linear response in the temperature testing and high-temperature sensitivity, which can be increased with the length of the FP cavity. The experimental results show that the temperature sensitivity reaches 1.174 nm/°C with a high linear response in the range of 30-60 °C. In addition, this sensor is insensitive to pressure and can be highly suitable for real-time water temperature monitoring for ocean research. The proposed ultraviolet glue-filled structure has the advantages of easy fabrication, high-temperature sensitivity, low cost and an arbitrary length of capillary, which has broad application prospects for marine survey technology, biological diagnostics and environmental monitoring.

Icariin inhibits isoproterenol-induced cardiomyocyte hypertropic injury through activating autophagy via the AMPK/mTOR signaling pathway.

Icariin (ICA), a bioactive flavonoid compound derived from Epimedium, have been demonstrated possessing anti-oxidative stress, anti-inflammation in the cardiovascular disease. But its effects on cardiomyocyte hypertrophy and the underlying mechanisms remains unclear. Here we found that ICA alleviated ISO-induced H9c2 or NRCM myocytes hypertrophy, assessed by surface area and the expression of ANP, BNP and ß-MHC. Furthemore, ICA reversed cardiomcytes enlargment by suppresing apoptotic injury and increasing autophagic flux. By contrast, 3-MA, an autophagy inhibitor, could abolished the antihypertrophic and pro-autophagic flux effects of ICA. Mechanistically, ICA increased the phosphorylation levels of AMPK and autophagy-related markers beclin-1, Atg5 and the LC3II/I ratio, and decreased phosphorylated mTOR. But the effects of ICA on ISO-induced cardiomyocytes hypertrophy were attenuated by selective AMPK inhibitor Compound C. In conclusion, these findings indicated that ICA attenuated cardiomyocyte hypertrophy induced by ISO and prevented cell injury, and the specific mechanism was mediated by AMPK/mTOR pathway to enhance autophagy and reduce autophagy-related cardiomyocyte apoptosis.

Changes in plant inputs alter soil carbon and microbial communities in forest ecosystems.

Global changes can alter plant inputs from both above- and belowground, which, thus, may differently affect soil carbon and microbial communities. However, the general patterns of how plant input changes affect them in forests remain unclear. By conducting a meta-analysis of 3193 observations from 166 experiments worldwide, we found that alterations in aboveground litter and/or root inputs had profound effects on soil carbon and microbial communities in forest ecosystems. Litter addition stimulated soil organic carbon (SOC) pools and microbial biomass, whereas removal of litter, roots or both (no inputs) decreased them. The increased SOC under litter addition suggested that aboveground litter inputs benefit SOC sequestration despite accelerated decomposition. Unlike root removal, litter alterations and no inputs altered particulate organic carbon, whereas all detrital treatments did not significantly change mineral-associated organic carbon. In addition, detrital treatments contrastingly altered soil microbial community, with litter addition or removal shifting it toward fungi, whereas root removal shifting it toward bacteria. Furthermore, the responses of soil carbon and microbial biomass to litter alterations positively correlated with litter input rate and total litter input, suggesting that litter input quantity is a critical controller of belowground processes. Taken together, these findings provide critical insights into understanding how altered plant productivity and allocation affects soil carbon cycling, microbial communities and functioning of forest ecosystems under global changes. Future studies can take full advantage of the existing plant detritus experiments and should focus on the relative roles of litter and roots in forming SOC and its fractions.

Portibacter marinus sp. nov., isolated from the sediment on the surface of plastics and proposal of a novel genus Neolewinella gen. nov. based on the genome-based phylogeny of the family Lewinellaceae.

A Gram-stain-negative, rod-shaped and orange-pigmented bacterial strain designated 10MBP4-2-1T was isolated from the sediment on the surface of a plastic straw collected from oyster-farming areas in Quanzhou Bay, PR China. Catalase activity and oxidase activity were positive. Flexirubin-type pigment was absent. The 16S rRNA gene of strain 10MBP4-2-1T showed highest sequence similarity to Portibacter lacus YM8-076T of 98.3 %. Phylogenetic analysis based on 16S rRNA gene sequences and 120 conserved concatenated proteins indicated that strain 10MBP4-2-1T was affiliated to the genus Portibacter and formed a monophyletic clade with P. lacus YM8-076T. The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity values between strain 10MBP4-2-1T and P. lacus YM8-076T were estimated to be 17.7, 70.4 and 70.3 %, respectively. The respiratory quinone was menaquinone 7. The major fatty acid composition was iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The draft genome size was 5 191 941 bp with DNA G+C content of 39.2 %. Based on phylogenetic analyses and whole genomic comparisons, strain 10MBP4-2-1T represents a novel species, for which the name Portibacter marinus sp. nov. is proposed. The type strain is 10MBP4-2-1T (=MCCC 1K07073T=KCTC 92101T). Additionally, phylogeny and whole genomic comparison of the family Lewinellaceae placed Lewinella cohaerens and the remaining Lewinella (currently comprising 11 species) in two clearly distinguishable clades recognized at the genus level. Thus, a novel genus named Neolewinella gen. nov. is proposed to accommodate the 11 species. Our study provides a taxonomic framework for the family Lewinellaceae based on genomic data.

The effect of prolonged holding time on the mechanical property and microstructural property of lithium disilicate glass-ceramic.

Repeat firing produces uncertainty about stabilizing lithium disilicate glass-ceramic (LDGC) material properties, even though prolonged holding time can enhance the mechanical property of LDGC during a single firing cycle. However, the effect of prolonged holding time and repeat firing on the mechanical property and microstructure of LDGC is not fully understood. In the present study, three groups of LDGC material were created: (i) extension of holding time (7 vs. 14 vs. 28 min) at 780-800 °C; (ii) holding time extension (7 vs. 14 min) and dual sintering at 800-820 °C, respectively; (iii) dual sintering with prolonged holding time (7 vs. 14 min) at 820-840 °C. The nano-indenter test revealed that prolonged holding time (14 and 28 min) promoted the enhancement of LDGC hardness and Young's modulus. X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy confirmed that prolonged holding time increased and stabilized LD phase in LDGC, as well as induced residual compressive stress. Scanning electron microscopy showed that prolonged holding time increased LD crystal grains homogeneously and facilitated LDGC to form dense interlocking structure without enlarging crystal size grains significantly. In contrast, LDGC that dual sintered alone at 820-840 °C possessed inferior mechanical properties, coupled with heterogeneous crystal phases, residual tensile stress, and melted crystals grains in the porous microstructure. Interestingly, these deteriorated properties of LDGC caused by dual sintering alone could be counteracted by prolonging the holding time. Nevertheless, the LDGC materials displayed an excellent biocompatibility throughout the study. This study identified that prolonged holding time during repeated firing cycles stabilized LD phase and crystal grain size of LDGC, thus enhanced the mechanical properties, which provided a new insight to extend the repeat fired restoration longevity of LDGC. Graphical abstract.

Pristimerin suppresses colorectal cancer through inhibiting inflammatory responses and Wnt/ß-catenin signaling.

Pristimerin, a triterpenoid, has exhibited potential anti-inflammatory and anti-tumor activities. Nevertheless, the role and mechanism of pristimerin in intestinal inflammation and colon cancer require further investigation. Here, we found that pristimerin protected mice from dextran sulfate sodium (DSS)-induced colitis, restoring epithelial damage and reducing tissue inflammation and inflammatory cell infiltration. In addition, pristimerin dramatically reduced the number and size of the tumors in a azoxymethane (AOM)/DSS-induced colitis-associated colorectal cancer (CAC) model. Furthermore, we found that pristimerin suppressed Wnt/ß-catenin signaling by RNA-Seq. Pristimerin inhibited Wnt/ß-catenin signaling via activation of GSK3ß, thereby suppressing Wnt target gene expression in colon cancer HCT116 and HT-29 cells. In HCT116 colon cancer xenografts and APCmin/+ mice, which undergo spontaneous intestinal tumorigenesis, administration of pristimerin reduced the tumor progression and decreased the expression of phosphorylated GSK3ß Ser 9, ß-catenin, cyclin D1 and c-Myc. These results suggest that pristimerin is a potent agent for preventing colon inflammation and carcinogenesis.

Microwave-assisted esterification and electro-enhanced solid-phase microextraction of omega-3 polyunsaturated fatty acids in eggs.

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs), a type of fatty acid that has many health benefits, are of increasing concern. Herein, we developed a method for the rapid esterification and enrichment of ω-3 PUFAs in eggs, which includes microwave-assisted esterification (MAE) and electrically enhanced solid-phase microextraction (EE-SPME). Combined with gas chromatographic, efficient detection of ω-3 PUFAs was achieved in eggs. Under microwave radiation, the esterification efficiency exhibited a significant increase ranging from 5.06 to 10.65 times. The EE-SPME method reduced extraction time from 50 to 15 min. In addition, improvements in extractive fiber coating materials were explored, which ensured efficient extraction of ω-3 PUFAs. Under the optimal conditions, the method displayed a low detection limit (1.01-1.54 µg L-1), good recoveries (85.82%-106.01%), and wide linear range (7.5-1000 µg L-1), which was successfully applied to determine ω-3 PUFAs in real egg samples.

Membrane-protected magnetic covalent organic framework for efficient extraction of estrogens in dairy products.

The presence of estrogens residues in dairy products is a growing concern due to their potential health risk. Herein, in this study, we have developed a membrane-protected magnetic solid-phase extraction (MP-MSPE) method that utilized a magnetic adsorbent (Fe3O4@COF-LZU1) with in-situ growth for the efficient extraction of estrone (E1), 17ß-estradiol (E2), and estriol (E3). When combined with HPLC-FLD, this method allows for the efficient detection of estrogens in dairy products. The stability of the MP-MSPE was improved by the presence of a dialysis membrane, which remained a high extraction efficiency (90 %) even after ten reuse cycles. The hydrogen bonding, π-π interactions and pore size effect contribute to the excellent adsorption of three estrogens onto Fe3O4@COF-LZU1. Under optimal conditions, the method exhibits a low detection limit (0.01-0.15 µg L-1), wide linear range (0.1-800 µg L-1), and favorable recoveries (77.3 %-109.4 %) at three concentration levels (10, 50 and 100 µg L-1). This proposed method is characterized by its simplicity, high efficiency and eco-friendliness, making it a promising approach for extracting estrogens from dairy products.

ADP-glucose pyrophosphorylase gene family in soybean and implications in drought stress tolerance.

BACKGROUND: ADP-glucose pyrophosphorylase (AGPase) is the key rate-limiting enzyme in starch biosynthesis pathway, and has been identified as a potential target for manipulation strategies aimed at improving crop yield and quality. OBJECTIVE: To identify the AGPase gene family members in soybean, and explore the potential implications of GmAGPS2 in drought stress tolerance. METHODS: The genome-wide identification and sequence analysis of soybean AGPase gene family was carried out by bioinformatics methods. The GmAGP gene expression was analyzed using transcriptome data and quantitative real-time PCR (qRT-PCR). Furthermore, transgenic yeast strains overexpressing GmAGPS2 were generated, and their growth was observed under drought stress. RESULTS: In this study, we searched for AGPase genes (GmAGP) in the soybean genome and identified a total of 14 GmAGP genes. The GmAGP proteins had a unique conserved NTP_transferase domain and were mainly located in the chloroplast and cytosol. Evolutionarily, the GmAGP proteins can be clustered into two distinct subgroups; within the same subgroup, they displayed a similar distribution pattern of conserved motifs. The GmAGP genes exhibited an uneven distribution on 10 chromosomes, and segmental duplication contributed to AGPase gene family expansion in soybean. The GmAGP genes presented different tissue expression pattern, in which GmAGPL6, GmAGPL9, and GmAGPL10 mainly exhibited tissue-specific expression pattern. The promoter of GmAGP genes had multiple cis-acting elements related to phytohormones and stress responses, and 8 GmAGP genes contained drought-responsive cis-acting elements. qRT‒PCR analysis demonstrated a significant upregulation expression of GmAGPL6, GmAGPL10, and GmAGPS2 in response to drought stress. Further functional analysis indicated that GmAGPS2 gene could improve yeast growth under drought stress conditions and enhance the drought tolerance of yeast. CONCLUSION: These results will contribute to further elucidation of the function of GmAGP genes, and offer important candidate genes for the genetic improvement of starch and yield-related traits and the breeding of high drought stress tolerance varieties in soybean.

Phosphorus availability regulates nitrogen fixation rate through a key diazotrophic assembly: Evidence from a subtropical Moso bamboo forest subjected to nitrogen application.

Biological N fixation (BNF) is an important N input process for terrestrial ecosystems. Long-term N application increases the availability of N, but may also lead to phosphorus (P) deficiency or an imbalance between N and P. Here, we performed a 5-year N application experiment in a subtropical Phyllostachys heterocycla forest in site and a P application experiment in vitro to investigate the effect of N application on the BNF rate and its regulatory factor. The BNF rate, nifH gene, free-living diazotrophic community composition and plant properties were measured. We found that N application suppressed the BNF rate and nifH gene abundance, whereas the BNF rate in soils with added P was significantly higher overall than that in soils without added P. Moreover, we identified a key diazotrophic assembly (Mod#2), primarily comprising Bradyrhizobium, Geobacter, Desulfovibrio, Anaeromyxobacter, and Pseudodesulfovibrio, which explained 77 % of the BNF rate variation. There was a significant positive correlation between the Mod#2 abundance and soil available P, and the random forest results showed that soil available P is the most important factor affecting the Mod#2 abundance. Our findings highlight the importance of soil P availability in regulating the activities of key diazotrophs, and thus increasing P supply may help to promote N accumulation and primary productivity through facilitating the BNF process in forest ecosystems.

Molecular characterization and expression pattern of Rubisco activase gene GhRCAß2 in upland cotton (Gossypium hirsutum L.).

BACKGROUND: Rubisco activase (RCA) is a pivotal enzyme that can catalyse the activation of Rubisco in carbon assimilation pathway. Many studies have shown that RCA may be a potential target for genetic manipulation aimed at enhancing photosynthetic efficiency and crop yield. OBJECTIVE: To understand the biological function of the GhRCAß2 gene in upland cotton, we cloned the coding sequence (CDS) of the GhRCAß2 gene and investigated its sequence features, evolutionary relationship, subcellular localization, promoter sequence and expression pattern. METHODS: The bioinformatics tools were used to analyze the sequence features of GhRCAß2 protein. Transient transformation of Arabidopsis mesophyll protoplasts was performed to determine the subcellular localization of the GhRCAß2 protein. The expression pattern of the GhRCAß2 gene was examined by analyzing transcriptome data and using the quantitative real-time PCR (qRT-PCR). RESULTS: The full-length CDS of GhRCAß2 was 1317 bp, and it encoded a protein with a chloroplast transit peptide. The GhRCAß2 had two conserved ATP-binding domains, and did not have the C-terminal extension (CTE) domain that was unique to the RCA α-isoform in plants. Evolutionarily, GhRCAß2 was clustered in Group A, and had a close evolutionary relationship with the soybean RCA. Western blot analysis demonstrated that GhRCAß2 was immunoreactive to the RCA antibody displaying a molecular weight similar to that of the RCA ß-isoform. The GhRCAß2 protein was found in chloroplast, aligning with its role as a vital enzyme in the process of photosynthesis. The GhRCAß2 gene had a leaf tissue-specific expression pattern, and the yellow-green leaf mutant exhibited a decreased expression of GhRCAß2 in comparison to the wild-type cotton plants. The GhRCAß2 promoter contained several cis-acting elements that respond to light, phytohormones and stress, suggesting that the expression of GhRCAß2 may be regulated by these factors. An additional examination of stress response indicated that GhRCAß2 expression was influenced by cold, heat, salt, and drought stress. Notably, diverse expression pattern was observed across different stress conditions. Additionally, low phosphorus and low potassium stress may result in a notable reduction in the expression of GhRCAß2 gene. CONCLUSION: Our findings will establish a basis for further understanding the function of the GhRCAß2 gene, as well as providing valuable genetic knowledge to improve cotton photosynthetic efficiency and yield under challenging environmental circumstances.

Decorin in the spatial control of collagen mineralization.

Understanding the molecular mechanism by which the periodontal ligament (PDL) is maintained uncalcified between two mineralized tissues (cementum and bone) may facilitate the functional repair and regeneration of the periodontium complex, disrupted in the context of periodontal diseases. However, research that explores the control of type I collagen (COL I) mineralization fails to clarify the detailed mechanism of regulating spatial collagen mineralization, especially in the periodontium complex. In the present study, decorin (DCN), which is characterized as abundant in the PDL region and rare in mineralized tissues, was hypothesized to be a key regulator in the spatial control of collagen mineralization. The circular dichroism results confirmed that DCN regulated the secondary structure of COL I, and the surface plasmon resonance results indicated that COL I possessed a higher affinity for DCN than for other mineralization promoters, such as DMP-1, OPN, BSP and DSPP. These features of DCN may contribute to blocking intrafibrillar mineralization in COL I fibrils during the polymer-induced liquid-precursor mineralization process when the fibrils are cross-linked with DCN. This effect was more remarkable when the fibrils were phosphorylated by sodium trimetaphosphate, as shown by the observation of a tube-like morphology via TEM and mineral sheath via SEM. This study enhances the understanding of the role of DCN in mineralization regulation among periodontal tissues. This provides insights for the development of biomaterials for the regeneration of interfaces between soft and hard tissues.

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Biological nitrogen (N) fixation is an important source of N in terrestrial ecosystems, but the response of soil microbial N fixation rate to N deposition in different forest ecosystems still remains uncertain. We conducted a field N addition experiment to simulate atmosphere N deposition in subtropical Pinus taiwanensis and Castanopsis faberi forests. We set up three levels of nitrogen addition using urea as the N source: 0 (control), 40 (low N), and 80 g N·hm-2·a-1(high N) to examine the chemical properties, microbial biomass C, enzyme activities, and nifH gene copies of top soils (0-10 cm). We also measured the microbial N fixation rate using the 15N labeling method. Results showed that N addition significantly reduced the soil microbial N fixation rate in the P. taiwanensis and C. faberi forests by 29%-33% and 10%-18%, respectively. Nitrogen addition significantly reduced N-acquiring enzyme (i.e., ß-1, 4-N-acetylglucosaminidase) activity and nifH gene copies in both forest soils. There was a significant positive correlation between the microbial N fixation rate and soil dissolved organic C content in the P. taiwanensis forest, but a significant negative relationship between the rate of soil microbial nitrogen fixation and NH4+-N content in the C. faberi forest. Overall, soil microbial N fixation function in the P. taiwanensis forest was more sensitive to N addition than that in the C. faberi forest, and the factors affecting microbial N fixation varied between the two forest soils. The study could provide insights into the effects of N addition on biological N fixation in forest ecosystems, and a theoretical basis for forest management.

Whole-soil warming leads to substantial soil carbon emission in an alpine grassland.

The sensitivity of soil organic carbon (SOC) decomposition in seasonally frozen soils, such as alpine ecosystems, to climate warming is a major uncertainty in global carbon cycling. Here we measure soil CO2 emission during four years (2018-2021) from the whole-soil warming experiment (4 °C for the top 1 m) in an alpine grassland ecosystem. We find that whole-soil warming stimulates total and SOC-derived CO2 efflux by 26% and 37%, respectively, but has a minor effect on root-derived CO2 efflux. Moreover, experimental warming only promotes total soil CO2 efflux by 7-8% on average in the meta-analysis across all grasslands or alpine grasslands globally (none of these experiments were whole-soil warming). We show that whole-soil warming has a much stronger effect on soil carbon emission in the alpine grassland ecosystem than what was reported in previous warming experiments, most of which only heat surface soils.

Prevalence of polycystic ovary syndrome in women in China: a large community-based study.

STUDY QUESTION: What is the prevalence of polycystic ovary syndrome (PCOS) in Han Chinese women from different communities? SUMMARY ANSWER: The prevalence of PCOS in Chinese women aged 19-45 years is 5.6%. WHAT IS KNOWN ALREADY: The prevalence of PCOS is reported to range from 5 to 10% but to the best of our knowledge the Han Chinese population has not been studied. STUDY DESIGN, SIZE, DURATION: A large-scale epidemiological study was carried out between October 2007 and September 2011 in 15 924 Han Chinese women of reproductive age (19-45 years) from the 10 provinces and municipalities in China. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 16 886 women from 152 cities and 112 villages were involved in the study. All study participants received a questionnaire and underwent a physical and transvaginal ultrasound examination. Blood samples were collected from a subsample of women (n = 3565) for analysis of metabolic markers and hormones. Based on the Rotterdam PCOS criteria, we assessed hyperandrogenism (H), chronic anovulation (O) and polycystic ovaries (P). Following diagnosis, women with PCOS were assigned to one of four different phenotypes. Finally, the prevalence and related risks of PCOS among Chinese women were estimated based on all the data sources. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 16 886 women were initially involved in the study and 15 924 eligible participants then completed the study; the overall response rate was 94.3% (15 924/16 886). The prevalence of PCOS in the Chinese community population was 5.6% (894/15 924). Blood samples were analyzed from 833 of these women who were assigned to the four PCOS phenotypes as follows: 19% H + O, 37% H + P, 15% O + P and 29% H + O + P. Comparing the 833 women with PCOS to 2732 women without PCOS indicated that PCOS occurs in younger women (P < 0.05) and these women were prone not only to menstrual problems, hyperandrogenism, PCO and infertility but also metabolic syndrome (MS) and insulin resistance (IR). However, there was no significant difference in the rate of hypertension or hyperlipemia between the two groups. Obese patients with PCOS had a higher rate of MS (16 versus 48%), IR (7 versus 28%), hypertension (8 versus 30%) and hyperlipemia (48 versus 73%) compared with non-obese patients (all P < 0.05), respectively. The rates of metabolic complications in patients with PCOS increased with age. LIMITATIONS, REASONS FOR CAUTION: Age and ethnic origin contribute to the differing manifestations of PCOS; therefore, sampling is one of the most important issues in epidemiological research into PCOS. Owing to the mobility of the Chinese population, the survey among resident populations caused a certain deviation in the age distribution. WIDER IMPLICATIONS OF THE FINDINGS: The prevention and treatment of PCOS, particularly in those who are obese, are essential in Chinese women of reproductive age.