Distinct Assembly Research Articles

Effect of Cathodic Protection Design for Galvanic-Coupled Components on Localized Corrosion Resistance of Aluminum Heat Exchanger

Abstract This study investigates the impact of cathodic protection design on the corrosion resistance of heat exchangers (HE#1, HE#2). Two distinct heat exchanger assemblies underwent a 720-hour cyclic corrosion test, revealing higher corrosion resistance in HE#2 compared to HE#1. The difference in cathodic protection design was observed at the fin-tube junction, where variations in the filler metal composition played a crucial role. Corrosion resistance was primarily influenced by the cathodic protection design at this junction rather than by the header-tube junction or the inherent corrosion susceptibility of the tube. Boundary element method simulations quantitatively confirmed that the tube's corrosion resistance was supported by the current provided at the fin-tube junction, particularly across the fin-free zone. Optimization of the cathodic protection design was achieved by adjusting the Zn content in the filler metal at the fin-tube junction. These findings provide valuable insights for enhancing corrosion resistance in practical heat exchanger applications.

Similar biogeographic patterns of abundant and rare bacterial communities are driven by distinct assembly mechanisms in grassland soils

Similar biogeographic patterns of abundant and rare bacterial communities are driven by distinct assembly mechanisms in grassland soils

Mechanical properties of two-dimensional material-based thin films: a comprehensive review.

Two-dimensional (2D) materials are materials with a thickness of one or a few atoms with intriguing electrical, chemical, optical, electrochemical, and mechanical properties. Therefore, they are deemed candidates for ubiquitous engineering applications. Films and three-dimensional (3D) structures made from 2D materials introduce a distinct assembly structure that imparts the inherent properties of pristine 2D materials on a macroscopic scale. Acquiring the adequate strength and toughness of 2D material structures is of great interest due to their high demand for numerous industrial applications. This work presents a comprehensive review of the mechanical properties and deformation behavior of robust films composed of 2D materials that help them to attain other extraordinary properties. Moreover, the various key factors affecting the mechanical performance of such thin films, such as the lateral size of nanoflakes, fabrication technique of the film, thickness of the film, post-processing, and strain rate, are elucidated.

Spatiotemporal distributions, co-occurrence networks, and assembly mechanisms of the bacterial community in sediments of the Yangtze River: comprehensive insights into abundant and rare taxa.

Sediments are key reservoirs for rare bacterial biospheres that provide broad ecological services and resilience in riverine ecosystems. Compared with planktons, there is a lack of knowledge regarding the ecological differences between abundant and rare taxa in benthic bacteria along a large river. Here, we offer comprehensive insights into the spatiotemporal distributions, co-occurrence networks, and assembly processes of three divided categories namely always rare taxa (ART), conditionally rare taxa (CRT), and conditionally rare and abundant taxa (CRAT) in sediments covering a distance of 4,300 km in the Yangtze River. Our study demonstrated that ART/CRT contributed greatly to the higher Chao-1 index, Shannon-Wiener index, and phylogenetic alpha diversity of benthic bacteria in autumn than in spring. ART showed high overall beta diversity, and CRT/CRAT exhibited more significant distance-decay patterns than ART in both seasons, mainly corresponding to macroscopic landform types. CRT predominated the nonrandom co-occurrence network, with 97% of the keystone species mostly affiliated with Acidobacteriota flourishing in the lower-reach plain. Two selection processes had the greatest influences on the assembly of CRT (74.7-77.6%), whereas CRAT were driven primarily by dispersal limitation (74.9-86.8%) and ART were driven by heterogeneous selection (33.9-48.5%) and undominated stochasticity (32.7-36.5%). Natural factors such as river flow and channel slope exhibited more significant correlations with community variation than nutrients in all three groups, and total organic carbon mediated the balance among the distinct assembly processes of the ART and CRT in both seasons. Taken together, these results provide an improved ecological understanding of the discrepancy in biogeographic patterns between abundant and rare bacterial taxa in the sediments of Asia's largest river.

Soil properties and microbial evolution during cropping system conversion: Insights from a 105-year study in southern China

Understanding the mechanisms by which soil environments and microbial communities evolve in response to long-term changes in cropping systems is essential for the development of effective ecological conservation and restoration strategies. In this study, variations of soil characteristics and the succession of microbial community assemblages and functions were investigated in southern Chinese deciduous forests and adjacent converted tea plantations at different ages (20, 40, 60, and 105 years). The results revealed significant alterations in soil properties and the emergence of distinct diversity patterns and assembly mechanisms for bacterial and fungal communities over the century-long succession period. Bacterial α-diversity exhibited a declining trend throughout succession, while fungal α-diversity experienced a rebound in the later stages. Null model analysis indicated that stochastic processes primarily drove the assembly of the bacterial community in both forests and tea plantations, whereas fungal community assembly gradually shifted from stochastic dominance to deterministic dominance. The strength of interactions between bacterial taxa in tea plantations decreased over time, but the topological properties of fungal networks were restored in tea plantations aged 60 and 105 years. The functional groups of bacteria associated with carbon cycling and saprotrophic fungi significantly increased after tea cultivation, which was closely linked to the proliferation of r-strategists stimulated by sufficient nutrients in tea plantations. It is noteworthy that in addition to typical environmental variables such as nutrients and pH, soil polyphenols in tea plantations also have a profound effect on the composition and assembly processes of bacterial and fungal communities. These findings advance the current understanding of how long-term cropping system changes affect soil microbial community assembly and functionality, and highlight the distinct strategies by which bacteria and fungi respond to cropping system change.

Distinct co-occurrence patterns and assembly processes of abundant and rare taxa under cadmium stress in volcanic areas

Microorganisms play a crucial role in coping with environmental stresses such as heavy metals in terrestrial ecosystems. However, elucidating the environmental adaptations and ecological processes of abundant and rare taxa is a core but less known theme. The diversity, co-occurrence networks, and the assembly processes of abundant and rare taxa were compared and analyzed in volcanic soils. The findings indicated that the shannon and richness of rare taxa was generally higher than that of abundant taxa. Furthermore, compared with rare taxa, abundant taxa indicated greater stability and resistance. Co-occurrence patterns revealed that abundant taxa exhibited a higher number of interspecific interactions in response to cadmium (Cd) stress, and fungi and archaea generated higher modularity in high Cd environment. Additionally, the assembly process of abundant taxa in volcanic soils was mainly influenced by stochastic processes, whereas deterministic processes were increasingly enhanced in rare taxa. These findings provide value for understanding the assembly processes of bacteria, fungi, and archaea, and conduce to a deeper comprehension of the environmental adaptations exhibited by both abundant and rare taxa in extreme volcanic environments.

“Tire plastisphere” in aquatic ecosystems: Biofilms colonizing on tire particles exhibiting a distinct community structure and assembly compared to conventional plastisphere

Tire particles (TPs) significantly contribute to microplastics in aquatic ecosystems, which has recently attracted ecological concerns worldwide. Numerous studies have shown that biofilms on microplastics harbor unique species and harmful functions, but it remains unclear whether TPs could offer distinct niches for biofilms compared to conventional microplastics (CP). This study investigated the succession and assembly of biofilms on TPs compared with CP over 60 days. Our results showed the community structures of biofilms on TPs and CP were distinct. Intriguingly, a greater structural dissimilarity was observed between TPs-associated communities and natural biofilms compared to that between CP-associated communities and natural biofilms. This dissimilarity became more pronounced as biofilms progressed through succession. Furthermore, the bacterial community on the TPs exhibits a network of greater complexity, more stable structure, and higher activity than that on the CP, but the pattern was reversed in the eukaryotic community. Deterministic processes had a more critical impact on bacterial communities on TPs, whereas distinct stochastic processes controlled eukaryotic communities on TPs (dispersal limitation) and CP (undominated processes). Altogether, this study tentatively introduced the term “tire plastisphere” (i.e., TP-attached biofilms), emphasizing TPs could serve as more artificial microbial habitats and pose potential risks in disturbing aquatic ecology.

Exploring the Impact of Contamination and Ageing on Proton Exchange Membrane Fuel Cells: Insights from Transmission Electron Microscopy

This paper presents a thorough investigation into the multifaceted impacts of contamination and ageing on the performance and structural integrity of proton exchange membrane fuel cells (PEMFCs) utilizing advanced Scanning Transmission Electron Microscopy (STEM). The study scrutinizes three distinct membrane electrode assemblies (MEAs): pristine, contaminated, and aged over an extensive operational period of 900 hours. Through meticulous analysis encompassing morphology and chemical composition, the intricate alterations induced by these factors are elucidated, providing invaluable insights into PEMFC degradation mechanisms.While contamination exhibited a seemingly minor influence on carbon distribution, profound effects were discerned on the ionomer and membrane constituents. Notably, a reduction in the perfluorinated backbone of polytetrafluoroethylene (PTFE) was evident, quantified by the ratio , standing at 2.07. This degradation significantly impeded the binding of catalysts and hindered ionic charge conduction, thereby fostering agglomeration and impeding ionic conductivity within the catalyst layer. Moreover, the aged MEA endured substantial carbon corrosion, resulting in the structural compromise of the carbon support layer.The repercussions of carbon corrosion were manifold, manifesting in a discernible decrease in the electrochemical active surface area (ECSA) attributable to platinum dissolution and re-deposition. Consequently, this led to an uneven distribution of platinum, forming clusters and exacerbating activation overpotential. These findings underscore the intricate interplay between contamination, ageing, and the ensuing structural and electrochemical alterations in PEMFCs, shedding light on critical degradation pathways.Furthermore, a comprehensive analysis of the aged MEA revealed notable changes in the microstructural characteristics, including an increase in pore size and surface roughness, indicative of progressive degradation mechanisms. These structural alterations were found to directly correlate with deteriorating performance metrics, emphasizing the pivotal role of microstructural integrity in PEMFC functionality.In conclusion, this study offers valuable insights into the intricate interplay between contamination, ageing, and structural degradation in PEMFCs, highlighting the urgent need for effective mitigation strategies to prolong lifespan and enhance performance. The findings presented herein serve as a crucial foundation for the development of advanced materials and design strategies aimed at enhancing the durability and efficiency of PEMFCs for diverse applications. Figure 1

Structure of Blm10:13S proteasome intermediate reveals parallel assembly pathways for the proteasome core particle.

Proteasomes are formed by chaperone-assisted assembly of core particles (CPs) and regulatory particles (RPs). The CP chaperone dimer Pba1/Pba2 binds early to proteasome subunits, and is thought to be replaced by Blm10 to form Blm10:CP, which promotes ATP-independent degradation of disordered proteins. Here, we present evidence of distinct parallel assembly pathways for CP by solving five cryo-EM structures including a Blm10:13S pre-assembly intermediate. Our data conflict with the current model of Blm10 and Pba1/Pba2 sequential activity in a single assembly pathway, as we find their CP binding is mutually exclusive and both are present on early and late assembly intermediates. CP affinity for Pba1/Pba2 is reduced during maturation, promoting Pba1/Pba2 release. We find Blm10 undergoes no such affinity switch, suggesting this pathway predominantly yields mature Blm10-bound CP. Altogether, our findings conflict with the current paradigm of sequential CP binding to instead indicate parallel assembly pathways by Pba1/Pba2 and Blm10.

Precise Control of Molecular Weight Characteristics of Charge-Shifting Poly(2-(N,N-Dimethylamino)Ethylacrylate) Synthesized by Reversible Addition-Fragmentation Chain Transfer Polymerization.

Poly(2-(N,N-dimethylamino)ethyl acrylate) (PDMAEA) is a promising charge-shifting polycation with the capacity to form a range of morphologically distinct polyelectrolyte assemblies. Nevertheless, the basic character of the monomer and its hydrolytic instability impedes its controlled synthesis to higher molecular weight (MW). Herein, the reversible addition-fragmentation chain transfer polymerization of DMAEA is reported using a tert-butanol/V70 initiator/trithiocarbonate-based chain transfer agent (CTA) polymerization setup. The CTA instability is demonstrated in the presence of the unprotonated tertiary amino group of the DMAEA monomer, which limits the control over the conversion and MW of the polymer. In contrast, the shielding of the amino groups by their protonation leads to polymerization with high conversions and excellent control over MWs of polymer up to 100000g mol-1. Hydrolytic degradation study at pH values ranging from 5 to 9 reveals that both basic and protonated PDMAEA undergo a pH-dependent hydrolysis. The proposed polymerization conditions provide a means of synthesizing PDMAEA with well-controlled characteristics, which are beneficial for controlling the complexation processes during the formation of various polyelectrolyte assemblies.

Essential tremor with tau pathology features seeds indistinguishable in conformation from Alzheimer's disease and primary age-related tauopathy.

Neurodegenerative tauopathies are characterized by the deposition of distinct fibrillar tau assemblies whose rigid core structures correlate with defined neuropathological phenotypes. Essential tremor (ET) is a progressive neurological disease that, in some cases, is associated with cognitive impairment and tau accumulation. Consequently, we explored the tau assembly conformation in ET patients with tau pathology using cytometry-based tau biosensor assays. These assays quantify tau prion seeding activity present in brain homogenates based on conversion of intracellular tau-fluorescent protein fusions from a soluble to an aggregated state. Prions exhibit seeding barriers, whereby a specific assembly structure cannot serve as a template for a native monomer if the amino acids are not compatible. We recently exploited the tau prion species barrier to define tauopathies by systematically substituting alanine (Ala) in the tau monomer and measuring its incorporation into seeded aggregates within biosensor cells. The Ala scan precisely classified the conformation of tau seeds from diverse tauopathies. We next studied 18 ET patient brains with tau pathology. Only one case had concurrent high amyloid-β plaque pathology consistent with Alzheimer's disease (AD). We detected robust tau seeding activity in 9 (50%) of the patients. This predominantly localized to the temporal pole and temporal cortex. We examined 8 ET cases with the Ala scan and determined that the amino acid requirements for tau monomer incorporation into aggregates seeded from these ET brain homogenates were identical to those of AD and primary age-related tauopathy (PART), and completely distinct from other tauopathies such as corticobasal degeneration, chronic traumatic encephalopathy, and progressive supranuclear palsy. Based on these studies, tau assembly cores in a pathologically confined subset of ET cases with high tau pathology are identical to AD and PART. This could facilitate more precise diagnosis and therapy for ET patients with cognitive impairment.

Expanding Insights: Harnessing Expansion Microscopy for Super-Resolution Analysis of HIV-1–Cell Interactions

Expansion microscopy has recently emerged as an alternative technique for achieving high-resolution imaging of biological structures. Improvements in resolution are achieved by physically expanding samples through embedding in a swellable hydrogel before microscopy. However, expansion microscopy has been rarely used in the field of virology. Here, we evaluate and characterize the ultrastructure expansion microscopy (U-ExM) protocol, which facilitates approximately four-fold sample expansion, enabling the visualization of different post-entry stages of the HIV-1 life cycle, focusing on nuclear events. Our findings demonstrate that U-ExM provides robust sample expansion and preservation across different cell types, including cell-culture-adapted and primary CD4+ T-cells as well as monocyte-derived macrophages, which are known HIV-1 reservoirs. Notably, cellular targets such as nuclear bodies and the chromatin landscape remain well preserved after expansion, allowing for detailed investigation of HIV-1–cell interactions at high resolution. Our data indicate that morphologically distinct HIV-1 capsid assemblies can be differentiated within the nuclei of infected cells and that U-ExM enables detection of targets that are masked in commonly used immunofluorescence protocols. In conclusion, we advocate for U-ExM as a valuable new tool for studying virus–host interactions with enhanced spatial resolution.

Mapping N2O production pathways in estuarine and coastal sediments through coupled 15N tracing and N2O isotopocules analysis

Estuarine and coastal zones are important sources of atmospheric nitrous oxide (N2O). Previous studies have explored the overarching roles of nitrification and denitrification in N2O production from these critical zones, yet the specific productions of various pathways within these processes remain elusive. Using dual 15N tracers (15NH4+ and 15NO3-) coupled with N2O isotopocules analysis, we quantified the contributions of multiple nitrification (both autotrophic and heterotrophic) and denitrification (bacterial, fungal, and chemical) pathways to N2O production in estuarine and coastal sediments. Furthermore, we leveraged microecology theory to dissect the biogeochemical mechanisms that govern the spatiotemporal dynamics of these pathways. Results showed that denitrification was the dominant process, accounting for over 70 % of N2O production. The remainder was attributed to autotrophic nitrification (5.80–23.92 %) and heterotrophic nitrification (1.07–7.10 %). Isotopocules analyses further showed that fungal denitrification was the primary source at freshwater sites (40.47–49.99 %), whereas bacterial denitrification prevailed at high-salinity sites (51.37–52.55 %). Moreover, these processes displayed contrasting spatial variability along the estuarine salinity gradient. Mechanistic investigation informed by microecology theory demonstrated that distinct assembly processes governed bacterial and fungal communities across this gradient, resulting in divergent ecological adaptation strategies of bacterial and fungal denitrifiers and, consequently, the contrasting contribution patterns of bacterial and fungal denitrification. Collectively, our work presents a comprehensive and refined picture of N2O sources and dynamics, offering essential insights for improving predictive models and formulating effective mitigation strategies targeting N2O emissions from estuarine and coastal zones.

Bond-centric modular design of protein assemblies.

We describe a modular bond-centric approach to protein nanomaterial design inspired by the rich diversity of chemical structures that can be generated from the small number of atomic valencies and bonding interactions. We design protein building blocks with regular coordination geometries and bonding interactions that enable the assembly of a wide variety of closed and opened nanomaterials using simple geometrical principles. Experimental characterization confirms successful formation of more than twenty multi-component polyhedral protein cages, 2D arrays, and 3D protein lattices, with a high (10-50 %) success rate and electron microscopy data closely matching the corresponding design models. Because of the modularity, individual building blocks can assemble with different partners to generate distinct regular assemblies, resulting in an economy of parts and enabling the construction of reconfigurable systems.

Photodynamic Therapy against Colorectal Cancer Using Porphin-Loaded Arene Ruthenium Cages

Colorectal cancer (CRC) is the third most common cancer in the world, with an ongoing rising incidence. Despite secure advancements in CRC treatments, challenges such as side effects and therapy resistance remain to be addressed. Photodynamic therapy (PDT) emerges as a promising modality, clinically used in treating different diseases, including cancer. Among the main challenges with current photosensitizers (PS), hydrophobicity and low selective uptake by the tumor remain prominent. Thus, developing an optimal design for PS to improve their solubility and enhance their selective accumulation in cancer cells is crucial for enhancing the efficacy of PDT. Targeted photoactivation triggers the production of reactive oxygen species (ROS), which promote oxidative stress within cancer cells and ultimately lead to their death. Ruthenium (Ru)-based compounds, known for their selective toxicity towards cancer cells, hold potential as anticancer agents. In this study, we investigated the effect of two distinct arene-Ru assemblies, which lodge porphin PS in their inner cavity, and tested them as PDT agents on the HCT116 and HT-29 human CRC cell lines. The cellular internalization of the porphin-loaded assemblies was confirmed by fluorescence microscopy. Additionally, significant photocytotoxicity was observed in both cell lines after photoactivation of the porphin in the cage systems, inducing apoptosis through caspase activation and cell cycle progression disruptions. These findings suggest that arene-Ru assemblies lodging porphin PS are potent candidates for PDT of CRC.

Illumination-Induced Solute Uptake in Liquid Crystal Droplets: The Role of 5CB Excimers.

This study investigates the phenomenon of solute uptake into liquid crystal (LC) droplets, illuminated under UV light, focusing on the role of 4-cyano-4'-pentylbiphenyl (5CB) excimer formation in this process. Our experiments reveal that upon UV irradiation solute molecules, including surfactants and dyes, are actively drawn into the LC phase, forming distinctive assemblies within the droplets. Contrary to previous assumptions that the uptake was driven by the direct photoreactivity of the solutes, we found that the 5CB excimer state plays a critical role for this phenomenon. This state, identifiable through its photoluminescence yet invisible to conventional UV/vis absorption spectroscopy, correlates strongly with the molecular assembly process inside of the droplets. Notably, this mechanism operates across a broad spectrum of solute molecules, from simple surfactants like sodium dodecyl sulfate (SDS) to complex dyes, demonstrating the generality of the excimer-induced solute uptake. The excimer's role is pivotal, facilitating solute incorporation without reliance on their inherent light-absorbing properties. This insight not only advances our understanding of LC behavior under light irradiation but also opens new avenues for designing light-responsive materials.

Pinewood nematode induced changes in the assembly process of gallery microbiomes benefit its vector beetle's development.

Microbiomes play crucial roles in insect adaptation, especially under stress such as pathogen invasion. Yet, how beneficial microbiomes assemble remains unclear. The wood-boring beetle Monochamus alternatus, a major pest and vector of the pine wilt disease (PWD) nematode, offers a unique model. We conducted controlled experiments using amplicon sequencing (16S rRNA and ITS) within galleries where beetles and microbes interact. PWD significantly altered bacterial and fungal communities, suggesting distinct assembly processes. Deterministic factors like priority effects, host selection, and microbial interactions shaped microbiome composition, distinguishing healthy from PWN-infected galleries. Actinobacteria, Firmicutes, and Ophiostomataceae emerged as potentially beneficial, aiding beetle's development and pathogen resistance. This study unveils how nematode-induced changes in gallery microbiomes influence beetle's development, shedding light on microbiome assembly amid insect-pathogen interactions. Insights gleaned enhance understanding of PWD spread and suggest novel management strategies via microbiome manipulation.IMPORTANCEThis study explores the assembly process of gallery microbiomes associated with a wood-boring beetles, Monochamus alternatus, a vector of the pine wilt disease (PWD). By conducting controlled comparison experiments and employing amplicon approaches, the study reveals significant changes in taxonomic composition and functional adaptation of bacterial and fungal communities induced by PWD. It identifies deterministic processes, including priority effects, host selection, and microbial interactions, as major drivers in microbiome assembly. Additionally, the study highlights the presence of potentially beneficial microbes such as Actinobacteria, Firmicutes, and Ophiostomataceae, which could enhance beetle development and resistance to pathogens. These findings shed light on the intricate interplay among insects, microbiomes, and pathogens, contributing to a deeper understanding of PWD prevalence and suggesting innovative management strategies through microbiome manipulation.

Hydrogeochemical differences drive distinct microbial community assembly and arsenic biotransformation in unconfined and confined groundwater of the geothermal system

High‑arsenic (As) groundwater in geothermal aquifers poses a serious threat to public health. Assembly processes governing groundwater microbial community related to As biotransformation are still unexplored in geothermal groundwater across different aquifers. To fill this gap, groundwater microorganisms, community assembly processes, and microbially metabolic coupling of carbon (C), nitrogen (N), phosphorus (P), sulfur (S), and arsenic (As) were investigated in unconfined and confined groundwater in the thermal reservoirs of the Guide Basin. The difference in groundwater hydrogeochemicals led to the heterogeneity of the microbial community and microbially mediated C, N, P, S, and As cycling between unconfined and confined groundwater. Higher temperature and As concentrations, low nutrient supply, and reduced conditions in confined groundwater supported stronger interspecific coexistence and environmental selection, thus promoting the proliferation of As-resistant microorganisms (ARMs) and simplifying the community assemblage. Abundant available nutrient supply and oxidizing conditions supported an increased species diversity and metabolic functionality in unconfined groundwater. S oxidizers, C fixation, and C degradation bacteria potentially contributed to the decreased As concentrations in unconfined groundwater. However, ARMs, ammonification, and anaerobic ammonia-oxidizing bacteria potentially caused As mobilization in confined groundwater. Overall, our results give a comprehensive insight into the interaction between As and microorganisms in geothermal groundwater.

Nonstructural protein 4 of human norovirus self-assembles into various membrane-bridging multimers

Single-stranded, positive-sense RNA ((+)RNA) viruses replicate their genomes in virus-induced intracellular membrane compartments. (+)RNA viruses dedicate a significant part of their small genomes (a few thousands to a few tens of thousands of bases) to the generation of these compartments by encoding membrane-interacting proteins and/or protein domains. Noroviruses are a very diverse genus of (+)RNA viruses including human and animal pathogens. Human noroviruses are the major cause of acute gastroenteritis worldwide, with genogroup II genotype 4 (GII.4) noroviruses accounting for the vast majority of infections. Three viral proteins encoded in the N-terminus of the viral replication polyprotein direct intracellular membrane rearrangements associated with norovirus replication. Of these three, nonstructural protein 4 (NS4) seems to be the most important, although its exact functions in replication organelle formation are unknown. Here we produce, purify and characterize GII.4 NS4. AlphaFold modeling combined with experimental data refine and correct our previous crude structural model of NS4. Using simple artificial liposomes, we report an extensive characterization of the membrane properties of NS4. We find that NS4 self-assembles and thereby bridges liposomes together. Cryo-EM, NMR and membrane flotation show formation of several distinct NS4 assemblies, at least two of them bridging pairs of membranes together in different fashions. Noroviruses belong to (+)RNA viruses whose replication compartment is extruded from the target endomembrane and generates double-membrane vesicles. Our data establish that the 21-kDa GII.4 human norovirus NS4 can, in the absence of any other factor, recapitulate in tubo several features, including membrane apposition, that occur in such processes.

Distinct influences of altitude on microbiome and antibiotic resistome assembly in a glacial river ecosystem of Mount Everest

The profound influences of altitude on aquatic microbiome were well documented. However, differences in the responses of different life domains (bacteria, microeukaryotes, viruses) and antibiotics resistance genes (ARGs) in glacier river ecosystems to altitude remain unknown. Here, we employed shotgun metagenomic and amplicon sequencing to characterize the altitudinal variations of microbiome and ARGs in the Rongbu River, Mount Everest. Our results indicated the relative influences of stochastic processes on microbiome and ARGs assembly in water and sediment were in the following order: microeukaryotes < ARGs < viruses < bacteria. Moreover, distinct assembly patterns of the microbiome and ARGs were found in response to differences in altitude, the latter of which shift from deterministic to stochastic processes with increasing differences in altitude. Partial least squares path modeling revealed that mobile genetic elements (MGEs) and viral β-diversity were the major factors influencing the ARG abundances. Taken together, our work revealed that altitude-caused environmental changes led to significant changes in the composition and assembly processes of the microbiome and ARGs, while ARGs had a unique response pattern to altitude. Our findings provide novel insights into the impacts of altitude on the biogeographic distribution of microbiome and ARGs, and the associated driving forces in glacier river ecosystems.