Effects of Continuous Cropping on Soil Microbial Flora and Research Progress of Continuous Cropping Obstacle Reduction Techniques

Continuous cropping can bring economic benefits in a short time and meet the growing demand of agricultural products such as grain,but long-term continuous cropping will accelerate soil degradation,lead to the reduction of crop yield and the increase of disease rate,and destroy the balance of soil microbial structure.Therefore,it is not conducive to the sustainable development of soil ecosystem.In this paper,the problems caused by continuous cropping,such as imbalance of soil microbial flora,decrease of biodiversity,accumulation of root exudates and their effects on soil fertility and crop growth,were summarized,and some measures were suggested to alleviate the obstacles of continuous cropping,such as reasonable rotation,adjustment of intercropping planting mode and application of biological fertilizers.Moreover,the paper also looked forward to the development trend of continuous cropping obstacle reduction techniques,including the integration and application of biological techniques,the promotion of green ecological techniques and the application of intelligent management system.This study provides theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promote the healthy and sustainable development of modern agriculture.

Impact of Continuous Cropping on Soil Phenolic Acid Substances and Research Progress on Continuous Cropping Obstacle Reduction Techniques

At present,long-term continuous cropping in agricultural production has formed a relatively common development trend.With the increase of continuous cropping years,soil phenolic acids are also affected to varying degrees.This paper summarized the effects of continuous cropping on soil phenolic acids and the research progress of continuous cropping obstacle reduction techniques,aiming at providing theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promoting the healthy and sustainable development of modern agriculture.

Research Progress on Effects of Continuous Cropping on Soil Microbial Florae and Its Restoration

Continuous cropping has become a common form of agricultural production at present, but with the increase of continuous cropping years, continuous cropping obstacles such as soil-borne diseases and plant growth potential decline are becoming more and more common. At present, the causes of continuous cropping obstacles and continuous cropping restoration have become a hot issue in agricultural research. This paper summarized the effects of continuous cropping obstacles on soil microbial community structure and main technical methods to repair continuous cropping obstacles, such as agricultural measure management, microbial balance adjustment and soil improvement, aiming to provide theoretical reference for protecting the sustainable utilization of soil ecosystem and ensuring the stability of crop production.

Recent progress on two-dimensional ferroelectrics:Material systems and device applications

Ferroelectrics are a type of material with a polar structure and their polarization direction can be inverted reversibly by applying an electric field.They have attracted tremendous attention for their extensive applications in non-volatile memory,sensors and neuromorphic computing.However,conventional ferroelectric materials face insulating and interfacial issues in the commercialization process.In contrast,two-dimensional(2D)ferroelectric materials usually have excellent semiconductor performance,clean van der Waals interfaces and robust ferroelectric order in atom-thick layers,and hold greater promise for constructing multifunctional ferroelectric optoelectronic devices and nondestructive ultra-high-density memory.Recently,2D ferroelectrics have obtained impressive breakthroughs,showing overwhelming superiority.Herein,firstly,the progress of experimental research on 2D ferroelectric materials is reviewed.Then,the preparation of 2D ferroelectric devices and their applications are discussed.Finally,the future development trend of 2D ferroelectrics is looked at.

Native Expanding <i>Merremia boisiana</i>Is Not More Allelopathic than Its Non-Expanding Congener <i>M. vitifolia</i>in the Expanded Range in Hainan

Exotic invaders may possess novel biochemical weapons that native plants do not have, and these novel biochemical weapons may be more allelopathic than those from native plants to other native competitors. During range expansion, native species also encounter many new plant competitors. Thus, allelochemicals from native expanding species may also be more novel and allelopathic than those from non-expanding species to other plant competitors in the expanded range. We test this hypothesis using the native expanding Merremia boisiana and its non-expanding congener M. vitifolia in year 2012 inthe expanded range inHainan. In petridish bioassays, we found that aqueous extracts of M. boisiana leaves were often less inhibitory or more stimulatory to seed germination and seedling growth of five vegetable species than those of M. vitifolia leaves. In pot culture, we also found that aqueous leaf extracts of the two congeners could both inhibit the growth of a naturally co-occurring plant Paederia scanden, but their effects did not differ from each other. These results indicate that while allelopathy may contribute to the competitive ability of M. boisiana, it may not act as a novel weapon explaining its success in the expanded range in Hainan.

Super-enhancer receives signals from the extracellular matrix to induce PD-L1-mediated immune evasion via integrin/ BRAF/TAK1/ERK/ETV4 signaling

Objective:PD-L1 and PD-L2 expression levels determine immune evasion and the therapeutic efficacy of immune checkpoint blockade.The factors that drive inducible PD-L1 expression have been extensively studied,but mechanisms that result in constitutive PD-L1 expression in cancer cells are largely unknown.Methods:DNA elements were deleted in cells by CRISPR/Cas9-mediated knockout.Protein function was inhibited by chemical inhibitors.Protein levels were examined by Western blot,mRNA levels were examined by real-time RT-PCR,and surface protein expression was determined by cellular immunofluorescence and flow cytometry.Immune evasion was examined by in vitro T cell-mediated killing.Results:We determined the core regions(chr9:5,496,378–5,499,663)of a previously identified PD-L1L2-super-enhancer(SE).Through systematic analysis,we found that the E26 transformation-specific(ETS)variant transcription factor(ETV4)bound to this core DNA region but not to DNA surrounding PD-L1L2SE.Genetic knockout of ETV4 dramatically reduced the expressions of both PD-L1 and PD-L2.ETV4 transcription was dependent on ERK activation,and BRAF/TAK1-induced ERK activation was dependent on extracellular signaling fromαvβ3 integrin,which profoundly affected ETV4 transcription and PD-L1/L2 expression.Genetic silencing or pharmacological inhibition of components of the PD-L1L2-SE-associated pathway rendered cancer cells susceptible to T cell-mediated killing.Conclusions:We identified a pathway originating from the extracellular matrix that signaled via integrin/BRAF/TAK1/ERK/ETV4 to PD-L1L2-SE to induce PD-L1-mediated immune evasion.These results provided new insights into PD-L1L2-SE activation and pathways associated with immune checkpoint regulation in cancer.

Construction and Analysis of SSH-cDNA Library from Leaves of Susceptible Rubber Clone Resistant to Powdery Mildew Induced by BTH

To understand the mechanism of benzothiadiazole (BTH)-induced susceptible rubber clone resistance to powdery mildew on gene level, a differentially expressed cDNA library was constructed by suppression subtractive hybridization (SSH) with rubber Reyan 7-33-97 clone. The constructed cDNA library was high integrity through detection of the critical processes of SSH, such as efficiency of adaptor connection, subtraction and conversion, as well as the type of recombinant genes. The positive rate was 99% after identification with random 400 white spots. The size of the cDNA clone inserted fragments was various but most in 400 bp - 1000 bp. There were 23 cDNA sequences matching the function of energy and basic metabolism, signal transduction, membrane and transport, secondary metabolism and so on after detection of the 42 positive clone sequences selected randomly from the cDNA library and comparison on nucleic acid sequences in Genbank. 7 ESTs were logged in Genbank and accession numbers were GW873071 and GW874604- GW874610. The results implicated that BTH could effectively induced rubber tree resistance to powdery mildew through increasing expresses of defense-related genes in leaves of rubber tree susceptible clone. It should provide a new approach for rubber disease management.

Integrated analysis of changes in soil microbiota and metabolites following long-term fertilization in a subtropical maize-wheat agroecosystem

Although the application of inorganic fertilizer is a widespread agronomic practice used to boost soil productivity and crop yields,the effects on soil microbiome and the metabolic mechanisms involved in the high-yield response of crops to long-term fertilization remain poorly described.In this study,combined metagenomic and metabolomic analyses were used to explore the mechanism of crop yield response to the 20-year application of nitrogen-phosphorus-potassium fertilizers in a subtropical agroecosystem in Southwest China.Soil bacterial and fungal communities were monitored using16S r RNA(bacteria)and internal transcribed spacer 1(ITS1)full-length gene(fungi)amplicon sequencing technologies,and metabolites were detected using a liquid chromatograph mass spectrometer.The results revealed that,in addition to providing nutrients,long-term fertilization shaped the compositions of bacteria and fungi to increase crop yields.Long-term fertilization significantly increased the relative abundances of plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi and promoted the secretion of soil metabolites such as carbohydrates,organic acids,and organic nitrogen compounds,which were primarily enriched in amino acid metabolism pathways.The increases in carbon and nitrogen sources and bioactive substances in soil promoted the increases in plant biomass and thereby maintained soil quality and production capacity.The findings highlighted the importance of soil metabolites in maintaining soil productivity as well as crop yields,and suggested that regulating key metabolites could increase crop yields in agroecosystems.

The Integrative Studies on the Functional A-to-I RNA Editing Events in Human Cancers

Adenosine-to-inosine(A-to-I)RNA editing,constituting nearly 90%of all RNA editing events in humans,has been reported to contribute to the tumorigenesis in diverse cancers.However,the comprehensive map for functional A-to-I RNA editing events in cancers is still insufficient.To fill this gap,we systematically and intensively analyzed multiple tumorigenic mechanisms of A-to-I RNA editing events in samples across 33 cancer types from The Cancer Genome Atlas.For individual candidate among1,500,000 quantified RNA editing events,we performed diverse types of downstream functional annotations.Finally,we identified 24,236 potentially functional A-to-I RNA editing events,including the cases in APOL1,IGFBP3,GRIA2,BLCAP,and miR-589-3p.These events might play crucial roles in the scenarios of tumorigenesis,due to their tumor-related editing frequencies or probable effects on altered expression profiles,protein functions,splicing patterns,and microRNA regulations of tumor genes.Our functional A-to-I RNA editing events(https://ccsm.uth.edu/CAeditome/)will help better understand the cancer pathology from the A-to-I RNA editing aspect.

Time-dependent mechanical behavior of tough hydrogels under multiaxial stretching

Understanding the time-dependent mechanical behavior of tough and viscoelastic hydrogels under complex external loading is crucial.In this study,we utilized tough and viscoelastic hydrogels synthesized through the copolymerization of methacrylic acid and methacrylamide as a model system to investigate their mechanical behavior under multiaxial stretching across a wide range of strain rates.Three stretching modes examined were uniaxial,pure shear,and equal biaxial stretching.Our findings show that under equal biaxial stretching,the hydrogels exhibit higher mechanical properties and energy dissipation compared to uniaxial and pure shear stretching,owing to the greater contribution of hydrogen bonds to energy dissipation in the former stretching mode.Additionally,employing the time-elongation separability method during the stretching process,we observed that the relaxation of dynamic hydrogen bonds in the hydrogels only depends on stretching time,independent of the elongation ratio and stretching modes.We anticipate that this study will yield valuable contributions to the design of durable load-bearing soft materials,particularly in dealing with complex deformation and strain rate responses.

大黄附子汤改善小鼠重症急性胰腺炎肠动力障碍的机制研究

目的揭示大黄附子汤改善重症急性胰腺炎小鼠早期肠动力障碍的机制。方法将27只SPF级雄性C57BL/6小鼠随机分为对照组、重症急性胰腺炎组(SAP)和大黄附子汤治疗组(DHFZT),每组9只。SAP组和DHZFT组采用腹腔注射20%L-精氨酸溶液复制SAP小鼠模型,对照组腹腔注射等渗盐水。DHFZT组分别于造模后12、24、36 h以0.2 mL大黄附子汤灌肠,对照组和SAP组分别以0.2 mL等渗盐水灌肠。造模后48 h,每组取3只小鼠测定小肠推进率,其余小鼠麻醉后取血、取材。ELISA法检测小鼠血清淀粉酶、血钙、内毒素、TNF-α和IL-6含量。HE染色观察胰腺和回肠组织病理学变化。Western blot定量检测回肠nNOS、ChAT、VIP、SP蛋白表达。结果与对照组相比,SAP组的抑制性神经元nNOS和VIP数量显著增加,兴奋性神经元ChAT和SP数量显著下降,小肠推进率显著降低,对应血清淀粉酶、内毒素、TNF-α和IL-6水平显著升高,差异有统计学意义(P均<0.05);与SAP组相比,DHFZT组的抑制性神经元nNOS和VIP数量显著下降,而兴奋性神经元ChAT和SP数量显著增加,小肠推进率显著增加,对应血清淀粉酶、内毒素、TNF-α和IL-6水平显著降低,血钙含量显著上升,差异有统计学意义(P均<0.05)。结论SAP小鼠早期发生肠动力障碍的机制可能存在肠神经系统的重塑,表现在抑制性神经元数量增加、兴奋性神经元数量减少,肠动力受抑制;大黄附子汤能够逆转肠神经系统的重塑,从而促进SAP小鼠肠动力的恢复。

The generation of PD-L1 and PD-L2 in cancer cells: From nuclear chromatin reorganization to extracellular presentation

The immune checkpoint blockade(ICB)targeting on PD-1/PD-L1 has shown remarkable promise in treating cancers.However,the low response rate and frequently observed severe side effects limit its broad benefits.It is partially due to less understanding of the biological regulation of PD-L1.Here,we systematically and comprehensively summarized the regulation of PD-L1 from nuclear chromatin reorganization to extracellular presentation.In PD-L1 and PD-L2 highly expressed cancer cells,a new TAD(topologically associating domain)(chr9:5,400,000-5,600,000)around CD274 and CD273 was discovered,which includes a reported super-enhancer to drive synchronous transcription of PD-L1 and PD-L2.The re-shaped TAD allows transcription factors such as STAT3 and IRF1 recruit to PD-L1 locus in order to guide the expression of PD-L1.After transcription,the PD-L1 is tightly regulated by mi RNAs and RNA-binding proteins via the long 3’UTR.At translational level,PD-L1 protein and its membrane presentation are tightly regulated by post-translational modification such as glycosylation and ubiquitination.In addition,PD-L1 can be secreted via exosome to systematically inhibit immune response.Therefore,fully dissecting the regulation of PD-L1/PD-L2 and thoroughly detecting PD-L1/PD-L2 as well as their regulatory networks will bring more insights in ICB and ICB-based combinational therapy.

Wearable membranes from zirconium-oxo clusters cross-linked polymer networks for ultrafast chemical warfare agents decontamination

The urgent need for immediate personal protection against chemical warfare agents(CWAs)spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices.Herein,as a new concept for CWA decontamination catalyst design,sub-nanoscale,catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures.The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt%and therefore,demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA,soman(GD)(t_(1/2)=5.0 min)and CWA simulant,methyl paraoxon(DMNP)(t_(1/2)=8.9 min).Meanwhile,due to the covalent nature of cross-linkages and the high flexibility of polymer strands,the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO_(2)and O_(2),enabling their extended applications in the field of collective/personal protective materials with body comfort.

Seed,cutting and air-layering reproductive inefficiency of noxious woody vine Merremia biosiana and its implications for management strategy

Merremia boisiana(Gagnep)van Ooststr.is a noxious fast growing woody vine and is able to grow overtop other plants,causing the death of plants underneath and forming monospecies stands.To formulate management responses,we assessed its seed and vegetative reproduction efficacy through indoor and field experiments.The number of flowers counted from bagged infructescences in Guangzhou ranged from 25 to 172,with an average of 80.80.Counting the seeds of bagged infructescences had shown that there were only 1.58 hard testa seeds in each infructescence.Seed vitality tests using red ink indicated that only 68.6%of hard testa and filled seeds were viable.The emergence rate of scarified hard testa seeds in the sand bed was 31.96%.Under imitated natural conditions,8%of hard testa seeds could germinate,and 9%still retained their germination potential in one year.Thus,seedlings should be monitored and removed in a timely fashion after any attempt of clearing.Moving soil or transplanting plant from infested patches should be strictly prohibited at least for several years.All considered,an infructescence contributed 0.3 seedlings.The investigation in the field found no seedlings either inside or at the perimeter of the patch,suggesting scant expansion by means of seed dispersal.Therefore,the elimination effort could be focused on a relatively restricted scale of patches.Of 630 cuttings of young shoots,old shoots and old lying shoots with or without growth regulators,there were only four(or 0.63%)established individuals.Air-layering shoots all died in two months.Poor cuttings and airlayering reproduction indicated that regeneration from fragments of removed stems or accidentally dropped ones was quite unlikely,and thus mechanical removal was safe.