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Our study focuses on the role of foreign capital which includes foreign direct investment, foreign aid, and economic freedom in poverty alleviation in developing and underdeveloped countries by using panel data from 1995 to 2018 for 71 countries. In the pursuit of achieving our objective, we employed several econometric techniques such as dynamic ordinary least square, fully modified ordinary least square, dynamic fixed effect, and pooled mean group regression methods. Furthermore, we performed the Granger causality test, impulse response function, and variance decomposition analysis. In our long-run estimations, we found that foreign direct investment could significantly alleviate poverty but increases poverty in the short run. Instead, foreign aid plays no significant role in poverty alleviation. Moreover, economic growth and economic freedom are essential as our findings consistently exhibited that they play a crucial role in poverty alleviation. We also found bidirectional causality between poverty alleviation and population growth, while a unidirectional causal linkage was found from poverty alleviation to foreign aid. We conclude that policymakers should look at a new paradigm of developmental assistance, and governments should also create an aiding environment for foreign investment to support their growth plan. First published online 13 December 2022

Here, we compare the porosity, microstructure and mechanical property of 4047 Al–Si alloys prepared by wire-arc additive manufacturing (WAAM) and conventional casting. X-ray microscopy reveals that WAAM causes a higher volume fraction of gas pores in comparison with conventional casting. Effective refinements of α-Al dendrites, eutectic Si particles and Fe-rich intermetallic compounds are achieved by WAAM, resulting from its rapid solidification process. Both ultimate tensile strength (UTS, up to 205.6 MPa) and yield stress (YS, up to 98.0 MPa) are improved by WAAM at the expense of elongation after fracture. The mechanical property anisotropy between scanning direction and build direction is minimal for alloys via WAAM. Additional microstructure refinement and strength enhancement are enabled by increasing the travel speed of welding torch from 300 to 420 mm/min.

The greening of the Earth over the last decades is predominantly indicated by the enhancements of leaf area index (LAI). Quantifying the relative contribution of multiple determinants, especially changes in climate and in land management changes (LMC), remains an arduous challenge. To solve this problem, we develop a simple yet novel data-driven method, called the Paired Land Use Experiment (PLUE), for mesoscale analysis. Using PLUE, we analyze vegetation development of the Sanjiang Plain, a transboundary plain between China and Russia, with roughly homogeneous climate but with distinct land management practices across the border-intensified agricultural development on China side (CNSP) versus largely little-disturbed natural vegetation on Russia side (RUSP). Both CNSP and RUSP LAI show significant trends (p < 0.05), with the annual variability reaching values of 9.8 × 10−3 yr−1 and 11.3 × 10−3 yr−1, respectively. However, in CNSP, the LAI increase is concentrated in the middle of the year, especially in five 8-day periods from 26 June to 28 July. During this period, the LAI trend ofCNSP is much higher than that of RUSP, at 92.7 × 10−3 yr−1 (p < 0.01) and 43.8 × 10−3 yr −1 (p < 0.01), respectively. Meanwhile, LAI decreased in CNSP at the begging and end of the growing season. The results show that different LMC practices lead to notably different seasonal variability in vegetation changes. The PLUE method offers a new potential tool in driver identification of vegetation greenness change based on observations. We argue for the necessity of parameterizing these different LMC in Earth system models.

A number of studies have suggested that the duration of a growing season has significantly lengthened during the past decades, but the connections between phenology variability and the terrestrial carbon cycle are far from clear. In this study, we used a process-based ecosystem simulation model, BIOME-BGC, to investigate spatio-temporal variation in phenology and its impacts on carbon fluxes in European forests during 1999–2013. We found that the start of vegetation growing season advanced on average by 0.22 ± 0.55 d yr−1 and the length of growing season extended on average by 0.42 ± 0.86 d yr−1 for the period 1999–2013. Model simulations indicated that European forests acted as a weak carbon (C) sink with a mean value of 0.27 Tg C yr−1 (1 Tg = 1012 g) during 1999–2013. Phenological variation lowered the net ecosystem exchange (NEE) by 3.99 Tg C for the same period, and this could be explained by the opposing effect of enhanced heterotrophic respiration directly induced by the extension of growing season. NEE effects were negatively correlated with heterotrophic respiration (R2 = 0.43), and one Tg increase in the heterotrophic respiration decreased NEE by 2.28 Tg C. The implications for the practical management is that a climate change will result in a significant change of selection pressure, and that phenology is a major aspect of tree functioning that will need adjusting for a future climate.

Accurate predictions of water vapor at large temporal and spatial scales are particularly important in global studies. In recent years, Central Asian grasslands have been subject to both intensive grazing and variability in climatic conditions. However, uncertainties about grazing on water cycling under climate change still exist. Therefore, the Biome-BGC grazing model was applied to assess the effects of grazing on evapotranspiration (ET) and water use efficiency (WUE). Three grassland types were studied during the period 1979–2011: forest meadow (FM), temperate grassland (TG) and desert grassland (DG). ET shows a gradual decreasing trend from FM (365.65 ± 36.86 mm m−2 yr−1) to DG (183.32 ± 21.15 mm m−2 yr−1), and WUE ranging from 0.62 ± 0.03 g C kg-1 H2O in FM to 1.12 ± 0.10 g C kg−1 H2O in TG, with an average of 0.83 ± 0.05 g C kg−1 H2O. Although there was a significant decrease in ET of 1.47–2.72 mm m−2 yr−1, WUE increased at a rate of 0.004 g C kg−1 H2O yr−1 in Central Asia. From 1979 to 2011, grazing lowered ET by 7.47% in Central Asia; the reduction rates for FM, TG and DG were 3.10%, 12.70% and 7.42%, respectively. In general, grazing decreased WUE by 3.60%. From non-grazed to grazed scenario, WUE increased by 6.86% for FM, but WUE decreased by 7.27% and 5.61% for TG and DG. An over-compensation of GPP under grazing might account for the higher WUE under certain grazing intensities. In order to achieve maximum utilization of water efficiency, proper grazing intensity for TG, DG and FM should be limited to 0.17, 0.39 and 0.38 head/ha, respectively.

Quantifying and mapping grassland human appropriation of net primary production (HANPP) is vital for the sustainable use of grasslands. However, grazing process was not effectively considered in previous studies, leading to biased results. Although grasslands are widespread in Central Asia, temporospatial patterns of HANPP in Central Asia grasslands are still unclear. In this study, to effectively consider grazing process, we used the Biome-Biogeochemical Cycles grazing model to estimate HANPP and explore its temporospatial patterns in Central Asia grasslands from 1979 to 2012. In our study, net primary production includes aboveground and belowground components. Our estimates showed that HANPP was 47 g C/m2/yr, which represented 34% of Central Asia grassland potential net primary production (NPPpot) and HANPP efficiency was 70% in this region. Interannual variations in HANPP and HANPP as a percentage of NPPpot (HANPP%NPPpot) were significantly positively related to grazing intensity (P

Grazing is a main human activity in the grasslands of Xinjiang, China. It is vital to identify the effects of grazing on the sustainable utilization of local grasslands. However, the effects of grazing on net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) in this region remain unclear. Using the spatial Biome-BGC grazing model, we explored the effects of grazing on NPP, ET and WUE across the different regions and grassland types in Xinjiang during 1979–2012. NPP, ET and WUE under the grazed scenario were generally lower than those under the ungrazed scenario, and the differences showed increasing trends over time. The decreases in NPP, ET and WUE varied significantly among the regions and grassland types. NPP decreased as follows: among the regions, Northern Xinjiang (16.60 g C/(m2•a)), Tianshan Mountains (15.94 g C/(m2•a)) and Southern Xinjiang (−3.54 g C/(m2•a)); and among the grassland types, typical grasslands (25.70 g C/(m2•a)), swamp meadows (25.26 g C/(m2•a)), mid-mountain meadows (23.39 g C/(m2•a)), alpine meadows (6.33 g C/(m2•a)), desert grasslands (5.82 g C/(m2•a)) and saline meadows (2.90 g C/(m2•a)). ET decreased as follows: among the regions, Tianshan Mountains (28.95 mm/a), Northern Xinjiang (8.11 mm/a) and Southern Xinjiang (7.57 mm/a); and among the grassland types, mid-mountain meadows (29.30 mm/a), swamp meadows (25.07 mm/a), typical grasslands (24.56 mm/a), alpine meadows (20.69 mm/a), desert grasslands (11.06 mm/a) and saline meadows (3.44 mm/a). WUE decreased as follows: among the regions, Northern Xinjiang (0.053 g C/kg H2O), Tianshan Mountains (0.034 g C/kg H2O) and Southern Xinjiang (0.012 g C/kg H2O); and among the grassland types, typical grasslands (0.0609 g C/kg H2O), swamp meadows (0.0548 g C/kg H2O), mid-mountain meadows (0.0501 g C/kg H2O), desert grasslands (0.0172 g C/kg H2O), alpine meadows (0.0121 g C/kg H2O) and saline meadows (0.0067 g C/kg H2O). In general, the decreases in NPP and WUE were more significant in the regions with relatively high levels of vegetation growth because of the high grazing intensity in these regions. The decreases in ET were significant in mountainous areas due to the terrain and high grazing intensity.

Drought, one of the most common natural disasters that have the greatest impact on human social life, has been extremely challenging to accurately assess and predict. With global warming, it has become more important to make accurate drought predictions and assessments. In this study, based on climate model data provided by the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), we used the Palmer Drought Severity Index (PDSI) to analyze and project drought characteristics and their trends under two global warming scenarios&mdash, 1.5 &deg, C and 2.0 &deg, C&mdash, in Central Asia. The results showed a marked decline in the PDSI in Central Asia under the influence of global warming, indicating that the drought situation in Central Asia would further worsen under both warming scenarios. Under the 1.5 &deg, C warming scenario, the PDSI in Central Asia decreased first and then increased, and the change time was around 2080, while the PDSI values showed a continuous decline after 2025 in the 2.0 &deg, C warming scenario. Under the two warming scenarios, the spatial characteristics of dry and wet areas in Central Asia are projected to change significantly in the future. In the 1.5 &deg, C warming scenario, the frequency of drought and the proportion of arid areas in Central Asia were significantly higher than those under the 2.0 &deg, C warming scenario. Using the Thornthwaite (TH) formula to calculate the PDSI produced an overestimation of drought, and the Penman&ndash, Monteith (PM) formula is therefore recommended to calculate the index.

Remarkable warm‒wet climate shifts and intensive cropland expansion strongly affected carbon (C) cycle and threaten agricultural sustainability in northwest China. In this study, we integrated a process-based ecosystem model and an empirical C bookkeeping model to investigate the coupled and isolated effects of arable land conversions and climate change (CLM) on regional C balance in a typical watershed of northwest China. Results revealed that the farmland area increased by 3367.31 km2 during 1979–2014. The combined effects of CLM with net cropland expansion enlarged the vegetation C (VEGC) and the soil organic C (SOC) stock by 2.83 and 11.83 Tg, respectively, and were strongest in 2008–2014. The conversions between desert grassland and cropland were the major driving forces for regional C balance. Cropland expansion shared equal effects on VEGC increase with CLM, but its effect on SOC increment was 53 times larger than CLM’s. VEGC was more responsive to CLM, whereas SOC gained more benefits from land management. The C sink from reclamation suffered from high water consumption and is facing great threats due to glaciers and mountain lake shrinking and groundwater overpumping. Water-saving irrigation techniques and environmentally friendly water use strategies are essential for local agricultural sustainability.

Dryland grasslands in Central Asia were prone to concurrent high levels of grazing intervention and climatic variability in the past decades. However, the influences of grazing on carbon cycling under climate change are still uncertain in this region. We modeled the carbon dynamics in Central Asia for different grassland types (i.e., Temperate Grassland, TG; Desert Grassland, DG; Forest Meadow, FM) that varied in grazing intensity from 1979 to 2011 by using the modified Biome-BGC grazing model. In addition, an inventory approach was also employed to estimate the CO2-eq emission from meat and milk production. The regional simulation estimated that the grassland ecosystems in Central Asia acted as a net carbon source with a value of 0.83 Pg C for the last 33 years (1 Pg = 1015 g). However, Central Asian grasslands had a weak carbon sink of 0.10 Pg when the grazing effect was eliminated. Grazing resulted in the release of 0.93 Pg C in Central Asia according to the modeling approach and 0.25–1.39 Pg C to inventory approach. Nevertheless, proper grazing intensities for TG, DG, and FM at approximately 0.23, 0.35, and 0.35 head ha−1, respectively, can result in overcompensation, which means that plants have higher productivity after herbivory compared with ungrazed condition under proper grazing intensity. These results can be attributed to the decreasing evapotranspiration (ET) in grazed grasslands, which can effectively promote grass growth. Therefore, restricting the grazing intensity to less than 0.23, 0.35, and 0.35 head ha−1 for TG, DG, and FM, respectively, to mitigate the degradation and maintain its carrying capacity for livestock is important. Our research explored the possible implications for grazing management of grasslands in Central Asia and concluded that grazing can eventually be assembled into a set of biophysical tools for climate adaptation and mitigation.

The effect of climate change on the spatio-temporal patterns of the terrestrial carbon dynamics in Central Asia have not been adequately quantified despite its potential importance to the global carbon cycle. Therefore, the modified BioGeochemical Cycles (Biome-BGC) model was applied in this study to evaluate the impacts of climatic change on net primary productivity (NPP) and net ecosystem productivity. Four vegetation types were studied during the period 1979 to 2011: cropland, grassland, forest, and shrubland. The results indicated that: (1) The climate data showed that Central Asia experienced a rise in annual mean temperature and a decline in precipitation from 1979 to 2011, (2) the mean NPP for Central Asia in 1979&ndash, 2011 was 281.79 gC m&minus, 2 yr&minus, 1, and the cropland had the highest NPP compared with the other vegetation types, with a value of 646.25 gC m&minus, 1, (3) grassland presented as a carbon source (&minus, 0.21 gC m&minus, 1), whereas the other three types were carbon sinks, (4) the four vegetation types showed similar responses to climate variation during the past 30 years, and grassland is the most sensitive ecosystem in Central Asia. This study explored the possible implications for climate adaptation and mitigation.

The antidiuretic hormone arginine vasopressin is a systemic effector in urinary concentration. However, increasing evidence suggests that other locally produced factors may also play an important role in the regulation of water reabsorption in renal collecting ducts. Recently, prostaglandin E2 (PGE2) receptor EP4 has emerged as a potential therapeutic target for the treatment of nephrogenic diabetes insipidus, but the underlying mechanism is unknown. To evaluate the role of EP4 in regulating water homeostasis, mice with renal tubule-specific knockout of EP4 (Ksp-EP4(-/-)) and collecting duct-specific knockout of EP4 (AQP2-EP4(-/-)) were generated using the Cre-loxP recombination system. Urine concentrating defect was observed in both Ksp-EP4(-/-) and AQP2-EP4(-/-) mice. Decreased aquaporin 2 (AQP2) abundance and apical membrane targeting in renal collecting ducts were evident in Ksp-EP4(-/-) mice. In vitro studies demonstrated that AQP2 mRNA and protein levels were significantly up-regulated in mouse primary inner medullary collecting duct (IMCD) cells after pharmacological activation or adenovirus-mediated overexpression of EP4 in a cAMP/cAMP-response element binding protein-dependent manner. In addition, EP4 activation or overexpression also increased AQP2 membrane accumulation in a mouse IMCD cell line (IMCD3) stably transfected with the AQP2 gene, mainly through the cAMP/protein kinase A and extracellular signal-regulated kinase pathways. In summary, the EP4 receptor in renal collecting ducts plays an important role in regulating urinary concentration under physiological conditions. The ability of EP4 to promote AQP2 membrane targeting and increase AQP2 abundance makes it a potential therapeutic target for the treatment of clinical disorders including acquired and congenital diabetes insipidus.

Central Asia has a land area of 5.6 × 10(6) km(2) and contains 80-90% of the world's temperate deserts. Yet it is one of the least characterized areas in the estimation of the global carbon (C) stock/balance. This study assessed the sizes and spatiotemporal patterns of C pools in Central Asia using both inventory (based on 353 biomass and 284 soil samples) and process-based modeling approaches. The results showed that the C stock in Central Asia was 31.34-34.16 Pg in the top 1-m soil with another 10.42-11.43 Pg stored in deep soil (1-3 m) of the temperate deserts. They amounted to 18-24% of the global C stock in deserts and dry shrublands. The C stock was comparable to that of the neighboring regions in Eurasia or major drylands around the world (e.g. Australia). However, 90% of Central Asia C pool was stored in soil, and the fraction was much higher than in other regions. Compared to hot deserts of the world, the temperate deserts in Central Asia had relatively high soil organic carbon density. The C stock in Central Asia is under threat from dramatic climate change. During a decadal drought between 1998 and 2008, which was possibly related to protracted La Niña episodes, the dryland lost approximately 0.46 Pg C from 1979 to 2011. The largest C losses were found in northern Kazakhstan, where annual precipitation declined at a rate of 90 mm decade(-1) . The regional C dynamics were mainly determined by changes in the vegetation C pool, and the SOC pool was stable due to the balance between reduced plant-derived C influx and inhibited respiration.

Information on the spatial distribution of soil salinity can be used as guidance in avoiding the continued degradation of land and water resources by better informing policy makers. However, most regional soil-salinity maps are produced through a conventional direct-linking method derived from historic observations. Such maps lack spatial details and are limited in describing the evolution of soil salinization in particular instances. To overcome these limitations, we employed a method that included an integrative hierarchical-sampling strategy (IHSS) and the Soil Land Inference Model (SoLIM) to map soil salinity over a regional area. A fuzzy c-means (FCM) classifier is performed to generate three measures, comprising representative grade, representative area, and representative level (membership). IHSS employs these three measures to ascertain how many representative samples are appropriate. Through this synergetic assessment, representative samples are obtained and their soil-salinity values are measured. These samples are input to SoLIM, which is constructed based on fuzzy logic, to calculate the soil-forming environmental similarities between representative samples and other locations. Finally, a detailed soil-salinity map is produced through an averaging function that is linearly weighted, which is used to integrate the soil salinity value and soil similarity. This case study, in the Uyghur Autonomous Region of Xinjiang of China, demonstrates that the employed method can produce soil salinity map at a higher level of spatial detail and accuracy. Twenty-three representative points are determined. The results show that 1) the prediction is appropriate in Kuqa Oasis (R 2 = 0.70, RPD = 1.55, RMSE = 12.86) and Keriya Oasis (R 2 = 0.75, RPD = 1.66, RMSE = 10.92), that in Fubei Oasis (R 2 = 0.77, RPD = 2.01, RMSE = 6.32) perform little better than in those two oases, according to the evaluation criterion. 2) Based on all validation samples from three oases, accuracy estimation show the employed method (R 2 = 0.74, RPD = 1.67, RMSE = 11.18) performed better than the multiple linear regression model (R 2 = 0.60, RPD = 1.47, RMSE = 14.45). 3) The statistical result show that approximately half (48.07%) of the study area has changed to salt-affected soil, mainly distributed in downstream of oases, around lakes, on both sides of rivers and more serious in the southern than the northern Xinjiang. To deal with this issue, a couple of strategies involving soil-salinity monitoring, water management, and plant diversification are proposed, to reduce soil salinization. Finally, this study concludes that the employed method can serve as an alternative model for soil-salinity mapping on a large scale.

Identifying the factors that determine the carbon source/sink strength of ecosystems is important for reducing uncertainty in the global carbon cycle. Using the modified Biome-BGC grazing model, we modeled carbon dynamics in Xinjiang, Northwest China for grasslands that varied in grazing intensity. In general, this regional simulation estimated that the grassland ecosystems in Xinjiang acted as a net carbon source, with a value of 0.38 Pg C over the period 1979–2007. There were significant effects of grazing on carbon dynamics. An over-compensatory effect in net primary productivity (NPP) and vegetation carbon (C) stock was observed when grazing intensity was lower than 0.40 head/ha. Grazing resulted in a net carbon source of 23.45 g C m−2 yr−1, which equaled 0.37 Pg in Xinjiang in the last 29 years. In general, grazing decreased vegetation C stock, while an increasing trend was observed with low grazing intensity. The soil C increased significantly (17%) with long-term grazing, while the soil C stock exhibited a steady trend without grazing. These findings have implications for grassland ecosystem management as it relates to carbon sequestration and climate change mitigation, e.g., removal of grazing should be considered in strategies that aim to increase terrestrial carbon sequestrations at local and regional scales. One of the greatest limitations in quantifying the effects of herbivores on carbon cycling is identifying the grazing systems and intensities within a given region. We hope our study emphasizes the need for large-scale assessments of how grazing impacts carbon cycling.

The farnesoid X receptor (FXR) is a ligand-activated transcription factor belonging to the nuclear receptor superfamily. FXR is mainly expressed in liver and small intestine, where it plays an important role in bile acid, lipid, and glucose metabolism. The kidney also has a high FXR expression level, with its physiological function unknown. Here we demonstrate that FXR is ubiquitously distributed in renal tubules. FXR agonist treatment significantly lowered urine volume and increased urine osmolality, whereas FXR knockout mice exhibited an impaired urine concentrating ability, which led to a polyuria phenotype. We further found that treatment of C57BL/6 mice with chenodeoxycholic acid, an FXR endogenous ligand, significantly up-regulated renal aquaporin 2 (AQP2) expression, whereas FXR gene deficiency markedly reduced AQP2 expression levels in the kidney. In vitro studies showed that the AQP2 gene promoter contained a putative FXR response element site, which can be bound and activated by FXR, resulting in a significant increase of AQP2 transcription in cultured primary inner medullary collecting duct cells. In conclusion, the present study demonstrates that FXR plays a critical role in the regulation of urine volume, and its activation increases urinary concentrating capacity mainly via up-regulating its target gene AQP2 expression in the collecting ducts.

Objective Metformin is a first-line antidiabetic drug for type 2 diabetes (T2D) with a relatively good safety profile. Metformin activates AMP-activated protein kinase (AMPK), which is crucial in maintaining renal medullary function, with inappropriate AMPK activation facilitating renal medullary interstitial cells (RMICs) apoptosis under hypertonic challenge. The present study was to determine the effects of metformin on RMIC survival in both normal and T2D mice. Methods Mice (C57BL/6, db/m, and db/db) were treated with 450 mg/kg metformin for 7 days and subjected to 24-h water restriction (=dehydration) before being killed. Cell apoptosis in the renal medulla was determined by the terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labeling (TUNEL) assay. Cultured RMIC were treated with 10 mmol/L metformin in the presence or absence of hypertonic stress. Cell viability was determined and the underlying mechanisms were investigated. Results Metformin induced significant apoptosis of RMIC in dehydrated normal mice and both hydrated and dehydrated T2D mice. Hypertonicity increased ATP production and inhibited AMPK phosphorylation in RMIC, which was attenuated by metformin. Metformin augmented hypertonicity-induced apoptosis of RMIC, suppressed the nuclear factor-κB/cyclo-oxygenase-2 pathway, reduced reactive oxygen species production and inhibited transcriptional activation of tonicity-responsive enhancer binding protein (TonEBP) and its downstream osmoprotective gene expression. Conclusions Metformin treatment is associated with increased RMIC apoptosis in both normally hydrated and dehydrated T2D mice. The results confirm AMPK as a critical factor involved in the maintenance of RMIC viability in T2D and raise safety concerns for metformin and other AMPK-activating antidiabetic drugs in dehydrated diabetic patients.

In this paper, we evaluate the extent of land use change and ecological security grades in the Manas River Basin, on the northern slopes of the Tianshan Mountains, from 1989–2002. Surveys were performed using Remote Sensing (RS) and Geographic Information System (GIS) means, and the relationship between land use change and ecological security was analyzed. The results are as follows: (i) the degree of land use change steadily increased in the Manas River Basin, and overall land use was in a state of development; (ii) From 1989–2002, the ecological security of the drainage basin generally improved somewhat, but deteriorated subsequently in some regions; (iii) the ecological security grade increased in regions with land use composite change extent values of 18–100, and ecological security grade improved from moderate warning in 1989 to early warning in 2002; and (iv) the cumulative areas of regions with relatively secure, and early-warning ecological security grade were ranked by land use degree in the order, V > IV > I > VI > III > II, showing that that regions with land use degree V (woodlands and grasslands) were important areas for ecological restoration and regeneration in this drainage basin, and that it was difficult to improve the ecological environment on sandy soils. We suggest that ecological security grades can be improved by increasing land use degree in regions where it is low.

Mountainous ecosystems are considered highly sensitive and vulnerable to natural disasters and climatic changes. Therefore, quantifying the effects of elevation on grassland productivity to understand ecosystem-climate interactions is vital for mountainous ecosystems. Water-use efficiency (WUE) provides a useful index for understanding the metabolism of terrestrial ecosystems as well as for evaluating the degradation of grasslands. This paper explored net primary productivity (NPP) and WUE in grasslands along an elevational gradient ranging from 400 to 3,400 m asl in the northern Tianshan Mountains-southern Junggar Basin (TMJB), Xinjiang of China, using the Biome-BGC model. The results showed that: 1) the NPP increased by 0.05 g C/(m2·a) with every increase of 1-m elevation, reached the maximum at the mid-high elevation (1,600 m asl), and then decreased by 0.06 g C/(m2·a) per 1-m increase in elevation; 2) the grassland NPP was positively correlated with temperature in alpine meadow (AM, 2,700–3,500 m asl), mid-mountain forest meadow (MMFM, 1,650–2,700 m asl) and low-mountain dry grassland (LMDG, 650–1,650 m asl), while positive correlations were found between NPP and annual precipitation in plain desert grassland (PDG, lower than 650 m asl); 3) an increase (from 0.08 to 1.09 g C/(m2·a)) in mean NPP for the grassland in TMJB under a real climate change scenario was observed from 1959 to 2009; and 4) remarkable differences in WUE were found among different elevations. In general, WUE increased with decreasing elevation, because water availability is lower at lower elevations; however, at elevations lower than 540 m asl, we did observe a decreasing trend of WUE with decreasing elevation, which may be due to the sharp changes in canopy cover over this gradient. Our research suggests that the NPP simulated by Biome-BGC is consistent with field data, and the modeling provides an opportunity to further evaluate interactions between environmental factors and ecosystem productivity.

Comprehensive understanding on the response of net primary production (NPP) to grazing is still elusive. It is necessary to choose a suitable study area with significant differences in climate, landform, diverse grasslands and grazing intensity (GI), to better understand plant–herbivore interactions and what environmental conditions NPP may increase. This study used Biome-BGC model with inclusion of a grazing process and the effects of the excreta on vegetation to investigate the effects of grazing on the aboveground NPP (ANPP) in Tianshan Mountains-Junggar Basin with four grasslands along a climatic gradient from mountain to plain, i.e., alpine meadow (AM), mid-mountain forest-meadow (MMFM), low-mountain dry grassland (LMDG), and plain desert grassland (PDG). The model simulated ANPP agreed well with the measured values for both non-grazed and grazed experiments at four sites, suggesting that the model successfully captured the effects of grazing on ANPP. The model results based on different GI scenarios indicated that ANPP decreased with increasing GI at AM and MMFM. But at LMDG and PDG, ANPP increased when GI was smaller than optimal GI (GIopt). After GIopt, ANPP decreased with the increasing GI. This implied that appropriate GI stimulated ANPP at LMDG and PDG, with magnitude of 4.1–22% at LMDG and 6.6–15.7% at PDG. By investigating the annual evapotranspiration (ET) and soil volumetric water content under non-grazed and grazed conditions, it was found that grazing reduced ET and hence improved soil water at sites LMDG and PDG, which explained the different response of ANPP to GI in different grasslands. We concluded that the response of ANPP to GI highly depended on the climatic conditions in grassland ecosystems over Central Asia, and moderate grazing can promote ANPP under water stress.

Cells residing in the hypertonic, hypoxic renal medulla depend on dynamic adaptation mechanisms to respond to changes in energy supply and demand. The serine/threonine kinase 5'-AMP protein kinase (AMPK) is a sensor of cellular energy status, but whether it contributes to the survival of cells in the renal medulla is unknown. Here, hypertonic conditions induced a decrease in AMPK phosphorylation within 12 hours in renal medullary interstitial cells (RMIC), followed by a gradual return to baseline levels. Activation of AMPK markedly increased hypertonicity-induced apoptosis of RMICs and suppressed both hypertonicity-induced NFκB nuclear translocation and cyclooxygenase-2 (COX-2) activation; overexpression of COX-2 significantly attenuated these effects. AMPK activation also markedly reduced generation of reactive oxygen species and nuclear expression of tonicity-responsive enhancer-binding protein, which prevented upregulation of osmoprotective genes. In vivo, pharmacologic activation of AMPK led to massive apoptosis of RMICs and renal dysfunction in the setting of water deprivation in mice. Taken together, these results identify a critical role for AMPK in the maintenance of RMIC viability and suggest that AMPK modulates the NFκB-COX-2 survival pathway in the renal medulla. Furthermore, this study raises safety concerns for the development of AMPK activators as anti-diabetic drugs, especially for patients prone to dehydration.

Objective— Restenosis after angioplasty remains a major clinical problem. Prostaglandin E 2 (PGE 2 ) plays an important role in vascular homeostasis. The PGE 2 receptor E-prostanoid 2 (EP2) is involved in the proliferation and migration of various cell types. We aimed to determine the role of EP2 in the pathogenesis of neointimal formation after vascular injury. Methods and Results— Wire-mediated vascular injury was induced in the femoral arteries of male wild-type (EP2+/+) and EP2 gene-deficient (EP2−/−) mice. In EP2+/+ mice, EP2 mRNA expression was increased in injured vessels for at least 4 weeks after vascular injury. Neointimal hyperplasia was markedly accelerated in EP2−/− mice, which was associated with increased proliferation and migration of vascular smooth muscle cells (VSMCs) and increased cyclin D1 expression in the neointima layer. Platelet-derived growth factor-BB (PDGF-BB) treatment resulted in more significant cell proliferation and migration in VSMCs of EP2−/− mice than in those of EP2+/+ mice. Activation and overexpression of EP2 attenuated PDGF-BB–elicited cell proliferation and migration, induced G 1 →S-phase arrest and reduced PDGF-BB–stimulated extracellular signal–regulated kinase phosphorylation in EP2+/+ VSMCs. Conclusion— These findings reveal a novel role of the EP2 receptor in neointimal hyperplasia after arterial injury. The EP2 receptor may represent a potential therapeutic target for restenosis after angioplasty.

Nonalcoholic fatty liver disease (NAFLD) is characterized by a massive accumulation of lipid droplets (LDs). The aim of this study was to determine the function of 17β-hydroxysteroid dehydrogenase-13 (17β-HSD13), one of our newly identified LD-associated proteins in human subjects with normal liver histology and simple steatosis, in NAFLD development. LDs were isolated from 21 human liver biopsies, including 9 cases with normal liver histology (group 1) and 12 cases with simple steatosis (group 2). A complete set of LD-associated proteins from three liver samples of group 1 or group 2 were determined by 2D LC-MS/MS. By comparing the LD-associated protein profiles between subjects with or without NAFLD, 54 up-regulated and 35 down-regulated LD-associated proteins were found in NAFLD patients. Among them, 17β-HSD13 represents a previously unidentified LD-associated protein with a significant up-regulation in NAFLD. Because the 17β-HSD family plays an important role in lipid metabolism, 17β-HSD13 was selected for validating the proteomic findings and exploring its role in the pathogenesis of NAFLD. Increased hepatic 17β-HSD13 and its LD surface location were confirmed in db/db (diabetic) and high-fat diet-fed mice. Adenovirus-mediated hepatic overexpression of human 17β-HSD13 induced a fatty liver phenotype in C57BL/6 mice, with a significant increase in mature sterol regulatory element-binding protein 1 and fatty acid synthase levels. The present study reports an extensive set of human liver LD proteins and an array of proteins differentially expressed in human NAFLD. We also identified 17β-HSD13 as a pathogenic protein in the development of NAFLD.

Spatial variation of phenology is a central feature of global change research. Satellite remote sensing is used for continental to global monitoring due to the limitations of long-term field observations of plant phenology. A threshold method was used to estimate the start of the season, length of the season, maximum normalized difference vegetation index (NDVI), and integral NDVI for selected tree species using remote sensing based NDVI data acquired by the VEGETATION instrument on board Satellite Pour l’Observation de la Terre (SPOT VGT NDVI). Afterward, the spatial patterns in the satellite-derived phenological metrics for four dominant tree species (i.e., beech, birch, pine, and spruce) across Europe were characterized. The results indicate that: (1) The SOS occurs 1.6–2.9 days later and the average LOS is 2.7–3 days shorter per 1 deg of latitude increase from south to north. (3) The SOS occurs 0.7–1.8 days later and the LOS was 0.6–2 days shorter per 100-m increase in altitude for the four species. (4) The SOS and LOS across Europe are well correlated with the mean annual air temperature (1°C correlates with a 4.5-day advance in the SOS and a 7-day extension in the LOS). Our research is the first one to characterize the spatial and temporal variations of phenology for different tree species across Europe using remote sensing.