Coronavirus disease 2019 is a newly emerging infectious disease currently spreading across the world. It is caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 ...(SARS-CoV-2). The spike (S) protein of SARS-CoV-2, which plays a key role in the receptor recognition and cell membrane fusion process, is composed of two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain that recognizes and binds to the host receptor angiotensin-converting enzyme 2, while the S2 subunit mediates viral cell membrane fusion by forming a six-helical bundle via the two-heptad repeat domain. In this review, we highlight recent research advance in the structure, function and development of antivirus drugs targeting the S protein.
We show an inconsistence of the novel 4D Einstein-Gauss-Bonnet gravity by considering a quantum tunneling process of vacua. Based on standard semiclassical techniques, we find a nonperturbative way ...to the study of the vacuum decay rate of the theory. We analytically compute all allowed cases in the parameter space. It turns out, without exception, that the theory either encounters a disastrous divergence of vacuum decay rate, or exhibits a confusing complex value of vacuum decay rate, or involves an instability (a large vacuum mixing). These suggest a strong possibility that the theory, at least the vacuum of the theory, is either unphysical or unstable, or has no well-defined limit as D→4.
A wide array of microorganisms, including many novel, phylogenetically deeply rooted taxa, survive and thrive in extreme environments. These unique and reduced-complexity ecosystems offer a ...tremendous opportunity for studying the structure, function and evolution of natural microbial communities. Marker gene surveys have resolved patterns and ecological drivers of these extremophile assemblages, revealing a vast uncultured microbial diversity and the often predominance of archaea in the most extreme conditions. New omics studies have uncovered linkages between community function and environmental variables, and have enabled discovery and genomic characterization of major new lineages that substantially expand microbial diversity and change the structure of the tree of life. These efforts have significantly advanced our understanding of the diversity, ecology and evolution of microorganisms populating Earth's extreme environments, and have facilitated the exploration of microbiota and processes in more complex ecosystems.
Tardigrades are remarkable for their ability to survive harsh stress conditions as diverse as extreme temperature and desiccation. The molecular mechanisms that confer this unusual resistance to ...physical stress remain unknown. Recently, tardigrade‐unique intrinsically disordered proteins have been shown to play an essential role in tardigrade anhydrobiosis. Here, we characterize the conformational and physical behaviour of CAHS‐8 from Hypsibius exemplaris. NMR spectroscopy reveals that the protein comprises an extended central helical domain flanked by disordered termini. Upon concentration, the protein is shown to successively form oligomers, long fibres, and finally gels constituted of fibres in a strongly temperature‐dependent manner. The helical domain forms the core of the fibrillar structure, with the disordered termini remaining highly dynamic within the gel. Soluble proteins can be encapsulated within cavities in the gel, maintaining their functional form. The ability to reversibly form fibrous gels may be associated with the enhanced protective properties of these proteins.
The conformational behaviour of an intrinsically disordered protein responsible for protecting tardigrades against extreme stress has been characterized. The protein assembles into fibres and fibrillar gels as a function of temperature and concentration. The disordered tails remain flexible within the gel cavities, which can encapsulate client proteins in their native state.
Summary
The Nutrition Transition model is presented with the nature and pace of change in key stages varying by location and subpopulations. At present, all high‐income and many low‐ and ...middle‐income countries are in a stage of the transition where nutrition‐related noncommunicable diseases including obesity, type 2 diabetes, and hypertension are dominating adult morbidity and mortality and are very high or growing rapidly in prevalence. Some countries still have key subpopulations facing hunger and undernutrition defined by stunting or extreme thinness among adults. We call these double burden of malnutrition countries. All low‐ and middle‐income countries face rapid growth in consumption of ultra‐processed food and beverages, but it is not inevitable that these countries will reach the same high levels of consumption seen in high‐income countries, with all the negative impacts of this diet on health. With great political and civil society commitment to adoption of policies shown in other countries to have improved dietary choices and social norms around foods, we can arrest and even reverse the rapid shift to diets dominated by a stage of high ultra‐processed food intake and increasing prevalence of nutrition‐related noncommunicable diseases.
Herein we present a new viologen‐based radical‐containing metal–organic framework (RMOF) Gd‐IHEP‐7, which upon heating in air undergoes a single‐crystal‐to‐single‐crystal transformation to generate ...Gd‐IHEP‐8. Both RMOFs exhibit excellent air and water stability as a result of favorable radical‐radical interactions, and their long‐lifetime radicals result in wide spectral absorption in the range 200–2500 nm. Gd‐IHEP‐7 and Gd‐IHEP‐8 show excellent activity toward solar‐driven nitrogen fixation, with ammonia production rates of 128 and 220 μmol h−1 g−1, respectively. Experiments and theoretical calculations indicate that both RMOFs have similar nitrogen fixation pathways. The enhanced catalytic efficiency of Gd‐IHEP‐8 versus Gd‐IHEP‐7 is attributed to intermediates stabilized by enhanced hydrogen bonding.
A single‐crystal‐to‐single‐crystal (SCSC) transformation of stable radical‐containing MOF Gd‐IHEP‐7 generates Gd‐IHEP‐8. It is accompanied by a marked increase in efficiency of sacrificial agent‐free photocatalytic nitrogen fixation to yield NH3 from H2O and N2 under simulated solar light irradiation at ambient temperature. The NH3 production rate of 220 μmol h−1 g−1 for Gd‐IHEP‐8 is a new record for MOF photocatalysts.
The plasticity and growth of plant cell walls (CWs) remain poorly understood at the molecular level. In this work, we used atomic force microscopy (AFM) to observe elastic responses of the root ...transition zone of 4‐day‐old Arabidopsis thaliana wild‐type and almt1‐mutant seedlings grown under Fe or Al stresses. Elastic parameters were deduced from force‐distance curve measurements using the trimechanic‐3PCS framework. The presence of single metal species Fe2+ or Al3+ at 10 µM exerts no noticeable effect on the root growth compared with the control conditions. On the contrary, a mix of both the metal ions produced a strong root‐extension arrest concomitant with significant increase of CW stiffness. Raising the concentration of either Fe2+ or Al3+ to 20 µM, no root‐extension arrest was observed; nevertheless, an increase in root stiffness occurred. In the presence of both the metal ions at 10 µM, root‐extension arrest was not observed in the almt1 mutant, which substantially abolishes the ability to exude malate. Our results indicate that the combination of Fe2+ and Al3+ with exuded malate is crucial for both CW stiffening and root‐extension arrest. However, stiffness increase induced by single Fe2+ or Al3+ is not sufficient for arresting root growth in our experimental conditions.
Summary statement
We investigate the change in stiffness of the external primary cell wall of living Arabidopsis thaliana seedlings in the presence of metallic stress using atomic force microscopy. Results reveal for the first time the uncoupling between mechanical response (CW stiffening) and root extension arrest.
Elton's biotic resistance hypothesis, which posits that diverse communities should be more resistant to biological invasions, has received considerable experimental support. However, it remains ...unclear whether such a negative diversity–invasibility relationship would persist under anthropogenic environmental change. By using the common ragweed (Ambrosia artemisiifolia) as a model invader, our 4‐year grassland experiment demonstrated consistently negative relationships between resident species diversity and community invasibility, irrespective of nitrogen addition, a result further supported by a meta‐analysis. Importantly, our experiment showed that plant diversity consistently resisted invasion simultaneously through increased resident biomass, increased trait dissimilarity among residents, and increased community‐weighted means of resource‐conservative traits that strongly resist invasion, pointing to the importance of both trait complementarity and sampling effects for invasion resistance even under resource enrichment. Our study provides unique evidence that considering species’ functional traits can help further our understanding of biotic resistance to biological invasions in a changing environment.
Whether biodiversity would consistently resist invasion under global change scenarios is poorly understood. Our four‐year grassland experiment showed that plant diversity was a consistent barrier to common ragweed invasion irrespective of nitrogen addition, and that plant diversity resisted invasion simultaneously through increases in the biomass, functional diversity, and dominance of conservative traits, of the resident communities.
Extracellular vesicles represent a rich source of novel biomarkers in the diagnosis and prognosis of disease. However, there is currently limited information elucidating the most efficient methods ...for obtaining high yields of pure exosomes, a subset of extracellular vesicles, from cell culture supernatant and complex biological fluids such as plasma. To this end, we comprehensively characterize a variety of exosome isolation protocols for their efficiency, yield and purity of isolated exosomes. Repeated ultracentrifugation steps can reduce the quality of exosome preparations leading to lower exosome yield. We show that concentration of cell culture conditioned media using ultrafiltration devices results in increased vesicle isolation when compared to traditional ultracentrifugation protocols. However, our data on using conditioned media isolated from the Non-Small-Cell Lung Cancer (NSCLC) SK-MES-1 cell line demonstrates that the choice of concentrating device can greatly impact the yield of isolated exosomes. We find that centrifuge-based concentrating methods are more appropriate than pressure-driven concentrating devices and allow the rapid isolation of exosomes from both NSCLC cell culture conditioned media and complex biological fluids. In fact to date, no protocol detailing exosome isolation utilizing current commercial methods from both cells and patient samples has been described. Utilizing tunable resistive pulse sensing and protein analysis, we provide a comparative analysis of 4 exosome isolation techniques, indicating their efficacy and preparation purity. Our results demonstrate that current precipitation protocols for the isolation of exosomes from cell culture conditioned media and plasma provide the least pure preparations of exosomes, whereas size exclusion isolation is comparable to density gradient purification of exosomes. We have identified current shortcomings in common extracellular vesicle isolation methods and provide a potential standardized method that is effective, reproducible and can be utilized for various starting materials. We believe this method will have extensive application in the growing field of extracellular vesicle research.
Low soil phosphorus (P) bioavailability causes the widespread occurrence of P‐limited terrestrial ecosystems around the globe. Exploring the factors influencing soil P bioavailability at large ...spatial scales is critical for managing these ecosystems. However, previous studies have mostly focused on abiotic factors. In this study, we explored the effects of microbial factors on soil P bioavailability of terrestrial ecosystems using a country‐scale sampling effort. Our results showed that soil microbial biomass carbon (MBC) and acid phosphatase were important predictors of soil P bioavailability of agro‐ and natural ecosystems across China although they appeared less important than total soil P. The two microbial factors had a positive effect on soil P bioavailability of both ecosystem types and were able to mediate the effects of several abiotic factors (e.g., mean annual temperature). Meanwhile, we revealed that soil phytase could affect soil P bioavailability at the country scale via ways similar to those of soil MBC and acid phosphatase, a pattern being more pronounced in agroecosystems than in natural ecosystems. Moreover, we obtained evidence for the positive effects of microbial genes encoding these enzymes on soil P bioavailability at the country scale although their effect sizes varied between the two ecosystem types. Taken together, this study demonstrated the remarkable effects of microbial factors on soil P bioavailability at a large spatial scale, highlighting the importance to consider microbial factors in managing the widespread P‐limited terrestrial ecosystems.
Understanding the factors influencing soil phosphorus (P) bioavailability at large spatial scales is critical to the development of managing strategies for P‐limited terrestrial ecosystems around the globe. However, previous studies have mostly focused on abiotic factors. Here, we explored the effects of not only abiotic factors but also microbial factors on soil P bioavailability of terrestrial ecosystems using a country‐scale sampling effort in China. We demonstrated that soil microbial biomass carbon (MBC), organic P‐mineralizing enzymes and microbial genes encoding these enzymes were important predictors of soil P bioavailability of agro‐ and natural ecosystems across China.
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