Responses of microbial activities and soil physical-chemical properties to the successional process of biological soil crusts in the Gurbantunggut Desert,Xinjiang

Biological soil crusts （BSCs） are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformation in BSCs. However, little is known about microbial activities and physical-chemical properties of BSCs in the Gurbantunggut Desert, Xinjiang, China. In the present research, a sampling line with 1-m wide and 20-m long was set up in each of five typical interdune areas selected randomly in the Gurbantunggut Desert. Within each sampling line, samples of bare sand sheet, algal crusts, lichen crusts and moss crusts were randomly collected at the depth of 0-2 cm. Varia- tions of microalgal biomass, microbial biomass, enzyme activities and soil physical-chemical properties in different succession of BSCs were analyzed. The relationships between microalgal biomass, microbial biomass, enzymatic activities and soil physical-chemical properties were explored by stepwise regression. Our results indicate that micro- algal biomass, microbial biomass and most of enzyme activities increased as the BSCs developed and their highest values occurred in lichen or moss crusts. Except for total K, the contents of most soil nutrients （organic C, total N, total P, available N, available P and available K） were the lowest in the bare sand sheet and significantly increased with the BSCs development, reaching their highest values in moss crusts. However, pH values significantly decreased as the BSCs developed. Significant and positive correlations were observed between chlorophyll a and microbial biomass C. Total P and N were positively associated with chlorophyll a and microbial biomass C, whereas there was a significant and negative correlation between microbial biomass and available P. The growth of cyanobacteria and microorganism contributed C and N in the soil, which offered substrates for enzyme activities thus increasing enzyme activities. Probably, improvement in enzyme activities increased soil fertility and promoted the growth of cyanobacteria, eukary- otic algae and heterotrophic microorganism, with the accelerating succession of BSCs. The present research found that microalgal-microbial biomass and enzyme activities played important roles on the contents of nutrients in the successional stages of BSCs and helped us to understand developmental mechanism in the succession of BSCs.

Ultrasound deep brain stimulation decelerates telomere shortening in Alzheimer’s disease and aging mice

Telomere length is a reliable biomarker for health and longevity prediction in both humans and animals.The common neuromodulation techniques,including deep brain stimulation(DBS)and optogenetics,have excellent spatial resolution and depth penetration but require implementation of electrodes or optical fibers.Therefore,it is important to develop methods for noninvasive modulation of telomere length.Herein,we reported on a new method for decelerating telomere shortening using noninvasive ultrasound deep brain stimulation(UDBS).Firstly,we found that UDBS could activate the telomerase-associated proteins in normal mice.Then,in the Alzheimer’s disease mice,UDBS was observed to decelerate telomere shortening of the cortex and myocardial tissue and to effectively improve spatial learning and memory abilities.Similarly,UDBS was found to significantly slow down telomere shortening of the cortex and peripheral blood,and improve motor and cognitive functions in aging mice.Finally,transcriptome analysis revealed that UDBS upregulated the neuroactive ligand-receptor interaction pathway.Overall,the present findings established the critical role of UDBS in delaying telomere shortening and indicated that ultrasound modulation of telomere length may constitute an effective therapeutic strategy for aging and aging-related diseases.

毛乌素沙地不同类型生物结皮细菌群落差异及其驱动因子

生物结皮在干旱半干旱区具有极为重要的生态功能,细菌是生物结皮中的重要微生物类群,在生物结皮形成、养分循环与调控过程中发挥着关键作用。然而,对于毛乌素沙地生物结皮演替过程中细菌群落多样性和关键环境因子的认识尚不清楚。因此,本文通过q PCR和高通量测序方法调查了毛乌素沙地裸地、藻结皮、地衣结皮和藓结皮之间的细菌丰度和群落多样性,并探究了生物结皮中细菌群落及其与关键环境因子之间的关系。结果表明,随着生物结皮的演替,细菌16S rRNA基因丰度呈显著上升趋势,细菌Chao1、Shannon指数和系统发育多样性呈先降低后增加的模式。生物结皮不同阶段的细菌门、目和属的相对丰度均存在显著差异,在裸地阶段优势细菌类群是拟杆菌门的噬几丁质菌目、放线菌门的红色杆菌目和变形菌门的根瘤菌目;藻结皮和地衣结皮中均以蓝藻门的颤藻目占绝对优势;藓结皮的细菌以拟杆菌门的噬几丁质菌目和变形菌门的根瘤菌目占优势。全磷、全氮、pH和总有机碳是影响土壤细菌群落的关键环境因子。综上所述,生物结皮的演替通过改变土壤理化特性,为细菌群落提供了不同生态位,其中,土壤养分和pH等环境因子对毛乌素沙地生物结皮细菌物种筛选和群落塑造发挥着重要作用。

High-Q collective Mie resonances in monocrystalline silicon nanoantenna arrays for the visible light

Dielectric optical antennas have emerged as a promising nanophotonic architecture for manipulating the propagation and localization of light.However,the optically induced Mie resonances in an isolated nanoantenna are normally with broad spectra and poor𝑄-factors,limiting their performances in sensing,lasing,and nonlinear optics.Here,we dramatically enhance the𝑄-factors of Mie resonances in silicon(Si)nanoparticles across the optical band by arranging the nanoparticles in a periodic lattice.We select monocrystalline Si with negligible material losses and develop a unique method to fabricate nanoparticle arrays on a quartz substrate.By extinction dispersion measurements and electromagnetic analysis,we can identify three types of collective Mie resonances with𝑄-factors∼500 in the same nanocylinder arrays,including surface lattice resonances,bound states in the continuum,and quasi-guided modes.Our work paves the way for fundamental research in strong light-matter interactions and the design of highly efficient light-emitting metasurfaces.

生物结皮演替对黄土高原水蚀风蚀交错区土壤氮素转化及微生物活性的促进效应

以黄土高原风蚀水蚀交错区六道沟小流域的生物结皮为研究对象,探索了土壤氮素含量、氮转化相关酶活性及微生物数量对生物结皮演替的响应规律及其在不同土层上的变化特征。结果表明:生物结皮演替显著增加了结皮层的有机碳(SOC)和NO3--N含量(P<0.05);结皮演替后期阶段的总氮(TN)、NH4+-N含量也逐渐增加;除脲酶、亚硝酸还原酶外,结皮层中固氮酶活性、蛋白酶活性、硝酸还原酶活性均随结皮演替呈显著增加趋势(P<0.05);微生物量碳和氮(MBC、MBN)亦随生物结皮演替而呈显著升高趋势(P<0.05);细菌、真菌同样在结皮演替后期数量增加。生物结皮层的土壤养分、酶活性和微生物数量等多数指标显著高于结皮下层土壤;生物结皮下层土壤的SOC含量、硝酸还原酶活性显著高于裸地下层,但不同结皮类型的下层土壤之间无显著差异;苔藓结皮下层土壤的脲酶活性和MBN最高,显著高于藻结皮和裸地下层土壤。土壤碳氮含量、微生物量与氮转化相关酶活性之间多数具有显著的相关关系。在生物结皮演替过程中,土壤SOC的积累增加了微生物量与细菌、真菌数量,氮功能微生物提高了氮素含量和相关酶活性,在氮素积累和转化过程中发挥着关键作用,为植物的繁衍与生长提供了宝贵的养分,促进黄土高原水蚀风蚀区的水土保持与地表稳定。

Association of KIR Genotypes and Haplotypes with Susceptibility to Chronic Hepatitis B Virus Infection in Chinese Han Population

Killer immunoglobulin-like receptor （KIR） genes can regulate the activation of NK and T cells upon interaction with HLA class I molecules. Hepatitis B virus （HBV） infection has been regarded as a multi-factorial disorder disease. Previous studies revealed that KIRs were involved in HCV and HIV infection or clearance. The aim of this study was to explore the possibility of the inheritance of KIR genotypes and haplotypes as a candidate for susceptibility to persistent HBV infection or HBV clearance. The sequence specific primer polymerase chain reaction （SSP-PCR） was employed to identify the KIR genes and pseudogenes in 150 chronic hepatitis B （CHB） patients, 251 spontaneously recovered （SR） controls, and 412 healthy controls. The frequencies of genotype G7 M, FZ1 increased in CHB patients compared with healthy control subjects. The frequency of genotype AH was higher in SR controls than that in both CHB patients and healthy controls. The carriage frequencies of genotype G and AH were higher; while, the frequencies of AF and AJ were lower in SR controls than those in healthy control subjects. The frequency of A haplotype was lower, whereas, the frequency of B haplotype was higher in CHB patients and SR controls than those in healthy controls. In healthy controls, haplotype 4 was found lower compared with that in CHB patients and SR controls and the frequency of haplotype 5 was higher in SR controls than that in other two groups. Based on these findings, it seems that the genotypes M and FZ1 are HBV susceptive genotypes; AH, on the other hand, may be protective genotypes that facilitate the clearance of HBV. It appears that the haplotype 4 is HBV susceptive haplotype, whereas, haplotype 5 may be the protective haplotype that facilitates the clearance of HBV. Cellular ＆ Molecular Immunology. 2008;5（6）：457-463.

Soil total organic carbon/total nitrogen ratio as a key driver deterministically shapes diazotrophic community assemblages during the succession of biological soil crusts

The diazotrophic community in biological soil crusts(biocrusts)is the key supplier of nitrogen in dryland.To date,there is still limited information on how biocrust development influences the succession of diazotrophic community,and what are the most important factors mediating diazotrophic communities during biocrust succession.Using the high throughput nifH amplicon sequencing,the diazotrophs in soils at different developmental stages of biocrust were comparatively studied.The results evidenced the decreases of TOC/TN ratio and pH value with biocrust development.Nostoc and Scytonema were the most dominant diazotrophic genera at all biocrust stages,while Azospirillum and Bradyrhizobium were abundant only in bare soil.Diazotrophic co-occurrence networks tended to be less complex and less connected with biocrust succession.The soil TOC/TN ratio was the most dominant factor mediating diazotrophic diversity,community composition and assembly processes,while diazotrophic-diversity and NO3–-N/NH4+-N ratio were positively correlated with the nitrogenase activity during biocrust succession.This study provided novel understandings of nitrogen fixation and succession patterns of diazotrophic community,by showing the effects of biocrust succession on diazotrophic diversity,community composition,community assembly and co-occurrence networks,and recognizing TOC/TN ratio as the most dominant factor mediating diazotrophs during biocrust succession.

Identification of serum metabolites enhancing inflammatory responses in COVID-19

Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),is characterized by a strong production of inflammatory cytokines such as TNF and IL-6,which underlie the severity of the disease.However,the molecular mechanisms responsible for such a strong immune response remains unclear.Here,utilizing targeted tandem mass spectrometry to analyze serum metabolome and lipidome in COVID-19 patients at different temporal stages,we identified that 611 metabolites(of 1,039)were significantly altered in COVID-19 patients.Among them,two metabolites,agmatine and putrescine,were prominently elevated in the serum of patients;and 2-quinolinecarboxylate was changed in a biphasic manner,elevated during early COVID-19 infection but levelled off.When tested in mouse embryonic fibroblasts(MEFs)and macrophages,these 3 metabolites were found to activate the NF-κB pathway that plays a pivotal role in governing cytokine production.Importantly,these metabolites were each able to cause strong increase of TNF and IL-6 levels when administered to wildtype mice,but not in the mice lacking NF-κB.Intriguingly,these metabolites have little effects on the activation of interferon regulatory factors(IRFs)for the production of type I interferons(IFNs)for antiviral defenses.These data suggest that circulating metabolites resulting from COVID-19 infection may act as effectors to elicit the peculiar systemic inflammatory responses,exhibiting severely strong proinflammatory cytokine production with limited induction of the interferons.Our study may provide a rationale for development of drugs to alleviate inflammation in COVID-19 patients.

Progress in the study of algae and mosses in biological soil crusts

Algae and mosses are not only two of the familiar communities in the process of desert vegetational succession,but also have the highest biomass in biological soil crusts.Meanwhile,being the pioneer plants,algae and mosses are involved in the establishment of biological soil crusts,which have great importance in arid environments and play a major role in desert ecosystems,such as being the indicator of the vegetation type,soil-holding,preventing erosion by water and wind,and sand fixation.This paper reviews the advances in the study of algae and mosses in arid and semi-arid areas.It mainly describes the ecological functions of algae and mosses including their influences on water cycle,circulation of substances,and community succession.In addition,the relationships between algae and mosses are discussed.Finally,some suggestions are proposed for the research orientations of algae and mosses in biological soil crusts.Ecologically,algae and mosses have significant ecological importance in arid areas,especially in those areas where environmental problems are becoming increasingly serious.

Chlorophytes of biological soil crusts in Gurbantunggut Desert,Xinjiang Autonomous Region,China

In this paper,chlorophytes collected from 253 biological soil crust samples in Gurbantunggut Desert in Xinjiang Autonomous Region,China were studied by field investigation and microscopical observation in lab.The flora composition,ecological distribution of chlorophytes in the desert and dynamic changes of species composition of chlorophytes in different developing stages of biological soil crusts are preliminarily analyzed.Results showed that there were 26 species belonging to 14 genera and 10 families,in which unicellular chlorophytes were dominant.There existed some differences in distribution of varied sand dune positions.The taxa of chlorophytes in leeward of sand dunes are most abundant,but the taxa in windward,interdune and the top of sand dunes reduced gradually.Chlorophytes were mainly distributed within the crust and the taxa of chlorophytes decrease obviously under the crust.In the devel-oping stages of the biological soil crust,species diversity of chlorophytes changed a little,but species composition pre-sented some differences.Chlorococcum humicola,Chlorella vulgaris,Chlamydomonas ovalis and Chlamydomonas sp.nearly existed in all developing stages of biological crusts.In several former stages of the biological soil crust there were spherical chlorophytes and filamentous ones.When moss crust formed,filamentous chlorophytes disappeared,such as Microspora and Ulothrix.

APOE interacts with ACE2 inhibitingg SARS-CoV-2 cellular entry and inflammation in COVID-19 patients

Apolipoprotein E(APOE)plays a pivotal role in lipid including cholesterol metabolism.The APOE 4(APOE4)allele is a major genetic risk factor for Alzheimer's and cardiovascular diseases.Although APOE has recently been associated with increased susceptibility to infections of several viruses,whether and how APOEand its isoforms affect SARS-CoV-2 infection remains unclear.Here,we show that serum concentrations of APOE correlate inversely with levels of cytokine/chemokine in 73 COVID-19 patients.Utilizing multiple protein interaction assays,we demonstrate that APOE3 and APOE4 interact with the SARS-CoV-2 receptor ACE2;and APOE/ACE2 interactions require zinc metallopeptidase domain of ACE2,a key docking site for SARS-CoV-2 Spike protein.In addition,immuno-imaging assays using confocal,super-resolution,and transmission electron microscopies reveal that both APOE3 and APOE4 reduce ACE2/Spikemediated viral entry into cells.Interestingly,while having a comparable binding affinity to ACE2,APOE4 inhibits viral entry to a lesser extent compared to APOE3,which is likely due to APOE4's more compact structure and smaller spatial obstacle to compete against Spike binding to ACE2.Furthermore,APOE e4 carriers clinically correlate with increased SARS-CoV-2 infection and elevated serum inflammatory factors in 142 COVID-19 patients assessed.Our study suggests a regulatory mechanism underlying SARS-CoV-2 infection through APOE interactions with ACE2,which may explain in part increased COVID-19 infection and disease severity in APOE e4 carriers.