Conversion of pure Chinese fir plantation to multi-layered mixed plantation enhances the soil aggregate stability by regulating microbial communities in subtropical China

Background:Soil aggregates are the basic units of soil structure,and their stability is a key indicator of soil quality and capacity to support ecosystem functions.The impacts of various environmental factors on soil aggregates have been widely studied.However,there remains elusive knowledge on the synergistic effects of changing forest stand structure on soil aggregate stability(SAS),particularly in subtropical China where soil erosion remains a critical issue.Methods:We investigated variations in the components of soil humus(HS),including humic acids(HAs),fulvic acids(FAs),and humins(HMs),under pure Chinese fir(Cunninghamia lanceolata)plantation(PP)and multilayered mixed plantation(MP)comprising C.lanceolata,Castanopsis hystrix,and Michelia hedyosperma.The state of soil aggregate stability,was determined by three separate methods,i.e.,dry-sieving,wet-sieving,and the Le Bissonnais.High-throughput sequencing was used to determine the diversity and composition of microbial communities under PP and MP.We then built partial least squares path models(PLS-PM)for assessing the responses of SAS to the variations in soil microorganisms and HS components.Results:The MP stands had significantly greater SAS(P<0.05),higher content of HAs and more rapid organic matter humification within aggregates,than the PP stands.High-throughput sequencing confirmed that the Pielou andα-diversity index values(Chao1 and Shannon)for fungi were all significantly higher under MP than under PP,while no marked difference was found in bacterialα-diversity between the two plantation types.Moreover,there were markedly greater abundance of three bacterial phyla(Verrucomicrobia,Chloroflexi,and Gemmatimonadetes)and three fungal phyla(Ascomycota,Kickxellomycota,and Glomeromycota),and significantly less abundance of two bacterial phyla(Planctomycetes and Firmicutes)and four fungal phyla(Basidiomycota,Mortierellomycota,Mucoromycota,and Rozellomycota)under MP than under PP.The Chloroflexi and Ascomycota phyla appeared to be the primary drivers of soil aggregate distribution.Our findings revealed that the promotion of SAS under MP was mainly driven by increased soil organic matter(SOM)content,which altered bacterial communities and enhanced fungal diversity,thereby increasing HAs content and the rate of organic matter humification.Conclusions:Considering the combined effects of enhanced soil quality,productivity,and relevant economic costs,introducing broadleaved tree species into Chinese fir plantations can be an effective strategy for stabilizing soil structure against erosion in subtropical China.Our study elucidated the controls on variations of SAS in Chinese fir-dominated plantations and demonstrated the benefit of converting pure Chinese fir plantation to multi-layered mixed plantations in increasing soil structural stability and improving site quality.

Two Ultraviolet Radiation Datasets that Cover China

Ultraviolet(UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

α/Sulfono-γ-AA peptide hybrids agonist of GLP-1R with prolonged action both in vitro and in vivo

Peptides are increasingly important resources for biological and therapeutic development,however,their intrinsic susceptibility to proteolytic degradation represents a big hurdle.As a natural agonist for GLP-1R,glucagon-like peptide 1(GLP-1)is of significant clinical interest for the treatment of type-2 diabetes mellitus,but its in vivo instability and short half-life have largely prevented its therapeutic application.Here,we describe the rational design of a series of a/sulfono-γ-AA peptide hybrid analogues of GLP-1 as the GLP-1R agonists.Certain GLP-1 hybrid analogues exhibited enhanced stability(t_(1/2)>14 days)compared to t_(1/2)(<1 day)of GLP-1 in the blood plasma and in vivo.These newly developed peptide hybrids may be viable alternative of semaglutide for type-2 diabetes treatment.Additionally,our findings suggest that sulfono-γ-AA residues could be adopted to substitute canonical amino acids residues to improve the pharmacological activity of peptide-based drugs.

A small molecule UPR modulator for diabetes identified by high throughput screening

Unfolded protein response(UPR) is a stress response that is specific to the endoplasmic reticulum(ER).UPR is activated upon accumulation of unfolded(or misfolded) proteins in the ER's lumen to restore protein folding capacity by increasing the synthesis of chaperones.In addition,UPR also enhances degradation of unfolded proteins and reduces global protein synthesis to alleviate additional accumulation of unfolded proteins in the ER.Herein,we describe a cell-based ultra-high throughput screening(uHTS) campaign that identifies a small molecule that can modulate UPR and ER stress in cellular and in vivo disease models.Using asialoglycoprotein receptor 1(ASGR) fused with Cypridina luciferase(CLuc) as reporter assay for folding capacity,we have screened a million small molecule library and identified APC655 as a potent activator of protein folding,that appears to act by promoting chaperone expression.Furthermore,APC655 improved pancreatic β cell viability and insulin secretion under ER stress conditions induced by thapsigargin or cytokines.APC655 was also effective in preserving β cell function and decreasing lipid accumulation in the liver of the leptin-deficient(ob/ob) mouse model.These results demonstrate a successful uHTS campaign that identified a modulator of UPR,which can provide a novel candidate for potential therapeutic development for a host of metabolic diseases.

Alterations of endotoxin distribution across different biofluids and relevant inflammatory responses by supplementing L-theanine in dairy cows during heat stress

The present trial was performed to reveal the regulatory effects of L-theanine on the levels of lipopolysaccharide(LPS)endotoxin within different biofluids,as well as relevant inflammatory responses of dairy cattle under heat stress conditions.Thirty lactating Chinese Holstein dairy cattle(189±47 d in milk,and 2±1 parities)were allocated in a completely randomized design to each of 3 dietary treatments:the control(CON,0 g/d per cow L-theanine),the low L-theanine dosage treatment(LL,16 g/d per cow L-theanine),and the high L-theanine dosage treatment(HL,32 g/d per cow L-theanine).This trial consisted of 38 d(7 d for adaption and 31 d for data and sample collection),and sample collection for rumen liquid,blood plasma or serum,and milk were conducted on the d 27 and 38,respectively.Dairy cattle were constantly exposed to environmental heat stress during this experiment according to the recorded temperature-humidity index(THI).In the LL treatment,LPS concentration in rumen liquid was higher(P<0.05),whilst LPS densities in plasma and milk were lower(P<0.05)than those of the CON.Supplementing L-theanine at 2 dosages both significantly lowered(P<0.05)the level of interleukin(IL)-1βin the serum.Results of the present study suggested that L-theanine could be a promising additive in reducing the detrimental effects of heat stress on dairy cows,and L-theanine supplementation at 16 g/d per cow is preferred because it reduced the LPS translocation into the peripheral blood and LPS accumulation in the milk,as well as mitigated LPS-induced inflammatory reactions in dairy cows during heat stress.Further studies are necessitated to investigate the underlying mechanisms of L-theanine in LPS alteration and inflammation alleviation.

Quantifying the short-term dynamics of soil organic carbon decomposition using a power function model

Introduction:Soil heterotrophic respiration(Rh,an indicator of soil organic carbon decomposition)is an important carbon efflux of terrestrial ecosystems.However,the dynamics of soil Rh and its empirical relations with climatic factors have not been well understood.Methods:We incubated soils of three subtropical forests at five temperatures(10,17,24,31,and 38°C)and five moistures(20,40,60,80,and 100%water holding capacity(WHC))over 90 days.Rh was measured throughout the course of the incubation.Three types of models(log-linear,exponential,and power model)were fitted to the measurements and evaluated based on the coefficient of determination(r2)and Akaike Information Criterion(AIC)of the model.Further regression analysis was used to derive the empirical relations between model parameters and the two climatic factors.Results:Among the three models,the power function model(Rh=R1 t−k)performed the best in fitting the descending trend of soil Rh with incubation time(r2>0.69 for 26 of 30 models).Both R1 and k generally increased linearly with soil temperature but varied quadratically with soil moisture in the three forest soils.Conclusions:This study demonstrated that the power function model was much more accurate than the exponential decay model in describing the decomposition dynamics of soil organic carbon(SOC)in mineral soils of subtropical forests.The empirical relations and parameter values derived from this incubation study may be incorporated into process-based ecosystem models to simulate Rh responses to climate changes.

Water transport of native and exotic tree species in relation to xylem anatomical characteristics in low subtropical China

Aims Exotic fast-growing tree species have been commonly planted as pioneer species to facilitate ecological restoration in South China.Their growth and resource utilization behavior related to intrinsic physiology and structural properties have profound influences on forest ecosystem.However,the contrastive research focusing on water utilization features along with xylem anatomical properties between native and exotic species is scarce in South China.The objective of this study is to investigate the sapwood anatomical characteristics and water utilization conditions of native and exotic fast-growing species,and to elucidate the relationship between sap-flux density and conduit features.Methods We measured sap-flux density,conduit length,diameter and density of four native species(Schima superba,Michelia mac-clurei,Castanopsis hystrix and Castanopsis fissa)and four exotic species(Eucalyptus citriodora,Eucalyptus urophylla×grandis,Acacia auriculaeformis and Acacia mangium).Sap flux density was measured based on the Granier’s thermal dissipation probe method.The whole-tree water transport was quantified by mul-tiplying sap-flux density by sapwood area.The measurements of conduit characteristics were conducted by using segregation and slice method.Important Findings Sapwood area increased with the growing diameter at breast height(DBH)as a power function.Native species had a larger water-conducting tissue area than exotic species at the same DBH value when trees grew to a size with a certain value of DBH.The con-duit diameter of exotic species was significantly larger than that of native species.Conversely,native species,such as S.superba and M.macclurei,had longer conduit length and higher conduit den-sity than other tree species.Based on a physiological interpretation of the measured conduit characteristics,native tree species devel-oped a safe water transport system while exotic fast-growing tree species come into being an efficient system instead.Water trans-port increased with the growing DBH as a power function,and the exponent for native species(1.60)was higher than that for exotic species(1.22).Under the combined impact of sap-flux density and sapwood area,native species presented a larger water transport at a larger DBH value,indicating that growth advantage of exotic fast-growing species might weaken as DBH increased.