Forage plants in grasslands with different topographies affect yak foraging preferences on the eastern Tibetan plateau.

Diet selection, a core problem of foraging behavior, is a nutritional adaptation strategy formed in the long-term natural selection process by grazing herbivores and is significant for the sustainable management of grassland. Studies have mainly focused on the impacts of the individual and whole community spatial characteristics and herbivore body status on herbivore foraging behavior; thus, the response and mechanism of forage plants in different terrains to the diet selection of grazing herbivores remains unclear. Therefore, in this study, forage plants (gramineae, cyperaceae, legume, forbs, edible shrubs, and community) in different topographies (terrace, riparian zones, shady slope, half shady slope, half sunny slope, sunny slope) on the eastern Tibetan plateau were selected to study changes in nutrient and mineral content characteristics of forage plants, as well as the difference in feeding bias of yaks for forage plants in different terrains by using an indoor cafeteria trial. A structural equation model was used to illustrate the impact of the forage plants in different terrains on the feeding bias of yak. The multi-criterion decision model TOPSIS showed that the nutritional value of gramineae was highest for the shaded slope, and that of cyperaceae and leguminosae was the highest for the terraces. The nutrient value of forbs and the whole community was highest for the sunny slope. Dry matter intake by yaks of leguminosae, forbs, and the whole plant community was significantly higher for terraces than for grasslands with other topographies, and all were significantly lower in riparian zones. Yak forage preference of leguminosae, forbs, and the whole community was the highest for the terrace and the lowest for the riparian zones. Structural equation modeling showed that for functional groups, the interactions between topography and functional groups were the drivers influencing yak forage preferences. Our study highlights the propensity of yaks to forage for plants in areas with different topographies. These results have provided a scientific basis for understanding the relationship between herbivores and plants in grasslands and for formulating scientific grazing management strategies, which are of considerable importance for sustainable grassland livestock husbandry.

Grazing exclusion alters soil methane flux and methanotrophic and methanogenic communities in alpine meadows on the Qinghai-Tibet Plateau.

Grazing exclusion (GE) is an effective measure for restoring degraded grassland ecosystems. However, the effect of GE on methane (CH4) uptake and production remains unclear in dominant bacterial taxa, main metabolic pathways, and drivers of these pathways. This study aimed to determine CH4 flux in alpine meadow soil using the chamber method. The in situ composition of soil aerobic CH4-oxidizing bacteria (MOB) and CH4-producing archaea (MPA) as well as the relative abundance of their functional genes were analyzed in grazed and nongrazed (6 years) alpine meadows using metagenomic methods. The results revealed that CH4 fluxes in grazed and nongrazed plots were -34.10 and -22.82 µg‧m-2‧h-1, respectively. Overall, 23 and 10 species of Types I and II MOB were identified, respectively. Type II MOB comprised the dominant bacteria involved in CH4 uptake, with Methylocystis constituting the dominant taxa. With regard to MPA, 12 species were identified in grazed meadows and 3 in nongrazed meadows, with Methanobrevibacter constituting the dominant taxa. GE decreased the diversity of MPA but increased the relative abundance of dominated species Methanobrevibacter millerae from 1.47 to 4.69%. The proportions of type I MOB, type II MOB, and MPA that were considerably affected by vegetation and soil factors were 68.42, 21.05, and 10.53%, respectively. Furthermore, the structural equation models revealed that soil factors (available phosphorus, bulk density, and moisture) significantly affected CH4 flux more than vegetation factors (grass species number, grass aboveground biomass, grass root biomass, and litter biomass). CH4 flux was mainly regulated by serine and acetate pathways. The serine pathway was driven by soil factors (0.84, p < 0.001), whereas the acetate pathway was mainly driven by vegetation (-0.39, p < 0.05) and soil factors (0.25, p < 0.05). In conclusion, our findings revealed that alpine meadow soil is a CH4 sink. However, GE reduces the CH4 sink potential by altering vegetation structure and soil properties, especially soil physical properties.

Response of soil microbial compositional and functional heterogeneity to grazing exclusion in alpine shrub and meadows in the Qinghai-Tibet Plateau.

Soil microorganisms found in shrub-meadow ecosystems are highly heterogeneous and extremely sensitive to grazing, but changes in microbial compositional and functional heterogeneity during grazing exclusion (GE) have been largely overlooked compared to community diversity. We collected soil samples from heavily grazed plots (6.0 sheep/ha) and GE plots (matrix and patch areas in both), and used a combination of next-generation sequencing, vegetation features, and the associated soil property data to investigate the effect of GE on the composition and function of microbial communities (bacteria fungi, and archaea) in 0-10 cm soils. Regarding community composition, the proportions of species in bacteria, fungi, and archaea were 97.3, 2.3, and 0.4%, respectively. GE significantly affected the species diversity of fungi and archaea but not that of bacteria. GE decreased the heterogeneity of bacteria (2.9% in matrix and 6.2% in patch) and archaea (31.1% in matrix and 19.7% in patch) but increased that of fungi by 1.4% in patch. Regarding community function, enzyme diversity and heterogeneity were increased by 10.4 and 9.4%, respectively, in patch after 6 years of fencing, exemplifying a high level of microbial functional redundancy. The Kyoto Encyclopedia of Genes and Genome pathways-cell growth and death, translation, digestive system, and nucleotide metabolism-were functional biomarkers (linear discriminant analysis effect size method) in matrix-non-grazed plots, whereas lipid metabolism, xenobiotics biodegradation and metabolism, and metabolism of terpenoids and polyketides, cell motility, cancer: overview, endocrine system, and membrane transport were biomarkers in patch-non-grazed plots. Additionally, GE improved the capacity for fatty acid metabolism but decreased the abundance of methane-producing archaea by 42.9%. Redundancy analysis revealed that the factors that affected microbial composition the most were soil aggregates, soil moisture, and the number of plant species, whereas those that affected microbial function the most were soil available phosphorus, soil temperature, and shrub canopy diameter. Our results quantified soil microbial heterogeneity, emphasizing the different responses of the composition and function of bacteria, fungi, and archaea to GE in alpine shrubs and meadows.

Effects of different intensities of long-term grazing on plant diversity, biomass and carbon stock in alpine shrubland on the Qinghai-Tibetan Plateau.

Grazing is the main grassland management strategy applied in alpine shrubland ecosystems on the Qinghai-Tibetan Plateau. However, how different intensities of long-term grazing affect plant diversity, biomass accumulation and carbon (C) stock in these ecosystems is poorly understood. In this study, alpine shrubland with different long-term (more than 30 years) grazing intensities (excluded from grazing for 5 years (EX), light grazing (LG), moderate grazing (MG) and heavy grazing (HG)) on the Qinghai-Tibetan Plateau were selected to study changes in plant diversity, aboveground biomass and C accumulation, as well as distribution of C stock among biomass components and soil depths. A structural equation model was used to illustrate the impact of grazing on the soil carbon stock (SOC). The results showed that the Shannon-Wiener diversity index and richness index of herbaceous plants, shrubs, and communities first significantly increased and then decreased with increasing grazing intensity, reaching maxima at the LG site. The aboveground and belowground and litter biomass of understory herbaceous plants, shrubs and communities decreased with increasing grazing intensity, reaching maxima at the EX site. The aboveground and belowground biomass C storage decreased with increasing grazing intensity, reaching maxima at the EX site. The SOC stock and total ecosystem C stock decreased with increasing grazing intensity, reaching maxima at the EX and LG sites. A structural equation model showed that grazing-induced changes in the belowground biomass of understory herbaceous plants greatly contributed to the SOC stock decrease. Thus, considering the utilization and renewal of grassland resources, as well as local economic benefits and ecological effects, LG may be a more rational grazing intensity for species diversity conservation and ecosystem C sequestration in alpine shrubland. Our results provide new insights for incorporating grazing intensity into shrub ecosystem C stock and optimizing grazing management and grassland ecosystem C management.

Long non-coding RNA NCK1-AS1 promotes the proliferation, migration and invasion of non-small cell lung cancer cells by acting as a ceRNA of miR-137.

Long noncoding RNAs (lncRNAs) have been shown to play important roles in carcinogenesis and progression. In this study, we mainly investigate the potential influence of lncRNA NCK1 antisense RNA 1 (NCK1-AS1) on the progression of non-small cell lung cancer (NSCLC). RT-PCR was performed to determine the expression of NCK1-AS1 and miR-137 in NSCLC specimens and cell lines. The clinical significance of NCK1-AS1 in 148 patients was analyzed statistically. The receiver operating characteristic (ROC) curve was performed to estimate the diagnostic value of NCK1-AS1 and miR-137. Regulatory effects of NCK1-AS1 on proliferative, colony formation abilities, metastasis and apoptosis of SK-MES-1 and H1299 cells were assessed through a series of functional experiments. RNA-pull down and Dual-Luciferase reporter assay was performed to verify the sponge effect of NCK1-AS1 on miR-137. We observed that NCK1-AS1 expression was upregulated, while miR-137 expression was down-regulated in NSCLC specimens and cell lines. Increased NCK1-AS1 expression was positively correlated with TNM stage and lymph node metastasis and poor clinical outcome. The diagnostic value of NCK1-AS1 and miR-137 expression was also confirmed. Functionally, knockdown of NCK1-AS1 suppressed the proliferation, migration and invasion of NSCLC cells, and promoted apoptosis. Moreover, NCK1-AS1 was able to adsorb miR-137 via a sponge effect. Overall, our findings suggested that NCK1-AS1 may be a candidate biomarker and a target for new therapies in NSCLC patients.

The diagnostic value of 18F-FDG PET/CT in identifying the causes of fever of unknown origin.

BACKGROUND: This study investigated the clinical significance of 18F-fluorodeoxyglucose positron emission tomography / computed tomography (18F-FDG PET/CT) in identifying the causes of fever of unknown origin (FUO). METHODS: Patients with a fever who received an 18F-FDG PET/CT examination were retrospectively selected. The means of the two groups were compared using an independent-samples t-test. RESULTS: Among the 89 included patients, 66 were diagnosed using 18F-FDG PET/CT. The sensitivity, specificity and diagnostic accuracy of 18F-FDG PET/CT for the diagnosis of patients with FUO were 84.5%, 25.8%, and 64.0%, respectively. The detection rates of 18F-FDG PET/CT for neoplastic diseases, infectious diseases and non-infectious inflammatory diseases were 100%, 61.3%, and 75%, respectively. The difference in C-reactive protein (CRP) levels between the two groups was statistically significant. CONCLUSIONS: 18F-FDG PET/CT has great clinical importance in diagnosing and identifying causes of FUO and improves the accuracy of FUO diagnosis when combined with serum CRP levels.

Economic Sulfur Conversion to Functional Polythioamides through Catalyst-Free Multicomponent Polymerizations of Sulfur, Acids, and Amines.

Sulfur utilization is a global concern because of its abundant nature sources and the safety or environmental problems caused by its burning or oxidation during storage, while sulfur-containing polymers are popular materials in virtue of their fascinating properties such as metal coordination ability, high refractive indices, and semiconducting property. The synthesis of sulfur-containing polymers is challenging, especially directly from elemental sulfur. Herein, catalyst-free and scalable multicomponent polymerizations (MCPs) of all commercially available elemental sulfur, dicarboxylic acids, and diamines were reported to facilely construct 12 polythioamides with diverse and well-defined structures, high molecular weights (Mw's up to 86 200 g/mol), and excellent yields (up to 99%) from elemental sulfur. Besides commonly used aliphatic diamines, aromatic diamine monomers are also applicable to these multicomponent polymerizations, affording polythioamides with unique rigid structures and improved functionality as compared to those of the previously reported polythioamides. These polythioamides can be applied in gold recovery, which could extract a trace amount of Au3+ from practical acidic leaching solution of discarded electronic waste selectively, rapidly (1 min), sensitively (10 ppb), and efficiently (>99.99%) with high extraction capacity up to 0.60 g· Au3+/g to directly afford high-purity elemental gold after pyrolysis. The MCPs could make use of both abundantly existing sulfur waste and trace amounts of precious gold residue in electronic wastes, demonstrating their great potential in resource utilization.

Nitrogen fertilizer regulates soil respiration by altering the organic carbon storage in root and topsoil in alpine meadow of the north-eastern Qinghai-Tibet Plateau.

Soil respiration (Rs) plays a critical role in the global carbon (C) balance, especially in the context of globally increasing nitrogen (N) deposition. However, how N-addition influences C cycle remains unclear. Here, we applied seven levels of N application (0 (N0), 54 (N1), 90 (N2), 126 (N3), 144 (N4), 180 (N5) and 216 kg N ha-1 yr-1 (N6)) to quantify their impacts on Rs and its components (autotrophic respiration (Ra) and heterotrophic respiration (Rh)) and C and N storage in vegetation and soil in alpine meadow on the northeast margin of the Qinghai-Tibetan Plateau. We used a structural equation model (SEM) to explore the relative contributions of C and N storage, soil temperature and soil moisture and their direct and indirect pathways in regulating soil respiration. Our results revealed that the Rs, Ra and Rh, C and N storage in plant, root and soil (0-10 cm and 10-20 cm) all showed initial increases and then tended to decrease at the threshold level of 180 kg N ha-1 yr-1. The SEM results indicated that soil temperature had a greater impact on Rs than did volumetric soil moisture. Moreover, SEM also showed that C storage (in root, 0-10 and 10-20 cm soil layers) was the most important factor driving Rs. Furthermore, multiple linear regression model showed that the combined root C storage, 0-10 cm and 10-20 cm soil layer C storage explained 97.4-97.6% variations in Rs; explained 94.5-96% variations in Ra; and explained 96.3-98.1% in Rh. Therefore, the growing season soil respiration and its components can be well predicted by the organic C storage in root and topsoil in alpine meadow of the north-eastern Qinghai-Tibetan Plateau. Our study reveals the importance of topsoil and root C storage in driving growing season Rs in alpine meadow on the northeast margin of Qinghai-Tibetan Plateau.

Six years of grazing exclusion is the optimum duration in the alpine meadow-steppe of the north-eastern Qinghai-Tibetan Plateau.

Grazing exclusion is an effective management strategy for restoring degraded grasslands worldwide, but the effects of different exclusion durations on vegetation structure and soil properties remain unclear. Therefore, we evaluated vegetation characteristics and soil properties in an alpine meadow-steppe under grazing exclusion of different lengths (with grazing and with 3-year, 6-year, 9-year and 11-year grazing exclusions) on the Qinghai-Tibetan Plateau (QTP). We also explored the relationships among above-ground biomass, biodiversity and soil properties to ascertain the mechanism underlying the impact of grazing exclusion on these factors. The results showed that the above- and below-ground biomass, total number of plant species, community density, Shannon-Wiener diversity index, evenness index, richness index, soil and vegetation carbon (C) and nitrogen (N) storage and ecosystem C and N storage exhibited a hump-shaped pattern in response to the length of grazing exclusion with a 6-year threshold. In addition, structural equation modelling showed that the bulk density, soil moisture content, micro sand content and clay and silt contents were the most important determining factors leading to an increase in above-ground biomass in the alpine meadow-steppe after grazing exclusion, whereas the soil total N, available N, available phosphate and soil organic C content were the most important determining factors leading to a decrease in biodiversity. Considering the stability of the plant community and the C and N pools, long-term grazing exclusion (>9 years) is unnecessary, and the optimum exclosure duration of the moderately degraded Elymus nutans - Kobresia humilis type alpine meadow-steppe is six years on the north-eastern QTP.

In vitro evaluation of antimicrobial combinations against imipenem-resistant Acinetobacter baumannii of different MICs.

BACKGROUND: This study was designed to verify the effectiveness of antimicrobial combination therapy against Acinetobacter baumannii isolates with different degrees of resistance to imipenem. METHODS: A total of twenty-one isolates with imipenem MICs of 16µg/ml (fifteen isolates) or 64µg/ml (six isolates), as identified using the Vitek II system, were included in this study. The MICs of all the isolates to each drug were confirmed again using the broth microdilution method, and a checkerboard assay was used for the assessment of the in vitro effectiveness of various antibiotic combinations. RESULTS: The results of susceptibility testing for single antibiotics indicated that imipenem-resistant Acinetobacter baumannii isolates exhibited good sensitivity to tigecycline and minocycline yet poor sensitivity to colistin, cefoperazone/sulbactam and levofloxacin. The distribution range of MICs for doripenem ranged from 0.5µg/ml to 128µg/ml, and the MICs ranged from 2µg/ml to 32µg/ml for levofloxacin. For combinations of imipenem and colistin, synergy was observed for the fourteen isolates with imipenem MICs of 16µg/ml and one isolate with an imipenem MIC of 64µg/ml. For the combinations of imipenem and cefoperazone/sulbactam, synergy was only observed for the fifteen isolates with imipenem MICs of 16µg/ml. The combinations of imipenem and fosfomycin showed synergy for twelve isolates with imipenem MICs of 16µg/ml. Other antimicrobial combinations based on colistin did not exhibit obvious synergy. CONCLUSION: The high sensitivity of tigecycline and minocycline in this study provides a reference for the clinical treatment of imipenem-resistant Acinetobacter baumannii infections in our region. The effectiveness of combination therapy may be predicted by the imipenem MICs of the isolates. The effect of fosfomycin in the combinations also reflects the clinical value of old drugs for new uses. These results suggest us that if we use carbapenem antibiotics in combination, more attention should be paid to the MICs of single drugs, and the economic costs should also be considered.