Membrane vesicles are the nano-sized vesicles originating from membranes. The production of membrane vesicles is a common feature among bacteria. Depending on the bacterial growth phase and ...environmental conditions, membrane vesicles show diverse characteristics. Various physiological and ecological roles have been attributed to membrane vesicles under both homeostatic and stressful conditions. Pathogens encounter several stressors during colonization in the hostile environment of host tissues. Nutrient deficiency, the presence of antibiotics as well as elements of the host's immune system are examples of stressors threatening pathogens inside their host. To combat stressors and survive, pathogens have established various defensive mechanisms, one of them is production of membrane vesicles. Pathogens produce membrane vesicles to alleviate the destructive effects of antibiotics or other types of antibacterial treatments. Additionally, membrane vesicles can also provide benefits for the wider bacterial community during infections, through the transfer of resistance or virulence factors. Hence, given that membrane vesicle production may affect the activities of antibacterial agents, their production should be considered when administering antibacterial treatments. Besides, regarding that membrane vesicles play vital roles in bacteria, disrupting their production may suggest an alternative strategy for battling against pathogens. Here, we aim to review the stressors encountered by pathogens and shed light on the roles of membrane vesicles in increasing pathogen adaptabilities in the presence of stress-inducing factors.
Deformability is an essential feature of blood cells (RBCs) that enables them to travel through even the smallest capillaries of the human body. Deformability is a function of (i) structural elements ...of cytoskeletal proteins, (ii) processes controlling intracellular ion and water handling and (iii) membrane surface-to-volume ratio. All these factors may be altered in various forms of hereditary hemolytic anemia, such as sickle cell disease, thalassemia, hereditary spherocytosis and hereditary xerocytosis. Although mutations are known as the primary causes of these congenital anemias, little is known about the resulting secondary processes that affect RBC deformability (such as secondary changes in RBC hydration, membrane protein phosphorylation, and RBC vesiculation). These secondary processes could, however, play an important role in the premature removal of the aberrant RBCs by the spleen. Altered RBC deformability could contribute to disease pathophysiology in various disorders of the RBC. Here we review the current knowledge on RBC deformability in different forms of hereditary hemolytic anemia and describe secondary mechanisms involved in RBC deformability.
We herein demonstrate robust two‐dimensional (2D) UFO‐shaped plasmonic supraparticles made of gold nanoparticles (AuNPs) and MnO2 nanosheets (denoted as AMNS‐SPs) for directly monitoring cell ...membrane vesiculation at the single‐particle level. Because the decorated MnO2 nanosheets are ultrathin (4.2 nm) and have large diameters (230 nm), they are flexible enough for deformation and folding for parceling of the AuNPs during the endocytosis process. Correspondingly, the surrounding refractive index of the AuNPs increases dramatically, which results in a distinct red‐shift of the localized surface plasmon resonance (LSPR). Such LSPR modulation provides a convenient and accurate means for directly monitoring the dynamic interactions between 2D nanomaterials and cell membranes. Furthermore, for the endocytosed AMNS‐SPs, the subsequent LSPR blue‐shift induced by etching effects of reducing molecules is promising for exploring the local environment redox states at the single‐cell level.
UFO‐shaped supraparticles were synthesized for the dynamic monitoring of the cell membrane vesiculation process at the single‐particle level.
Gram-negative bacteria produce outer membrane vesicles (OMVs) that contain biologically active proteins and perform diverse biological processes. Unlike other secretion mechanisms, OMVs enable ...bacteria to secrete insoluble molecules in addition to and in complex with soluble material. OMVs allow enzymes to reach distant targets in a concentrated, protected, and targeted form. OMVs also play roles in bacterial survival: Their production is a bacterial stress response and important for nutrient acquisition, biofilm development, and pathogenesis. Key characteristics of OMV biogenesis include outward bulging of areas lacking membrane-peptidoglycan bonds, the capacity to upregulate vesicle production without also losing outer membrane integrity, enrichment or exclusion of certain proteins and lipids, and membrane fission without direct energy from ATP/GTP hydrolysis. Comparisons of similar budding mechanisms from diverse biological domains have provided new insight into evaluating mechanisms for outer membrane vesiculation.
Silencing of the CHLOROPLAST VESICULATION gene leads to plant stress tolerance and increased nitrogen assimilation in rice.
Abstract
Abiotic stress-induced senescence in crops is a process ...particularly affecting the photosynthetic apparatus, decreasing photosynthetic activity and inducing chloroplast degradation. A pathway for stress-induced chloroplast degradation that involves the CHLOROPLAST VESICULATION (CV) gene was characterized in rice (Oryza sativa) plants. OsCV expression was up-regulated with the age of the plants and when plants were exposed to water-deficit conditions. The down-regulation of OsCV expression contributed to the maintenance of the chloroplast integrity under stress. OsCV-silenced plants displayed enhanced source fitness (i.e. carbon and nitrogen assimilation) and photorespiration, leading to water-deficit stress tolerance. Co-immunoprecipitation, intracellular co-localization, and bimolecular fluorescence demonstrated the in vivo interaction between OsCV and chloroplastic glutamine synthetase (OsGS2), affecting source-sink relationships of the plants under stress. Our results would indicate that the OsCV-mediated chloroplast degradation pathway is involved in the regulation of nitrogen assimilation during stress-induced plant senescence.
The lack of a simple, fast and efficient method for protein delivery is limiting the widespread application of in-cell experiments, which are crucial for understanding the cellular function. We ...present here an innovative strategy to deliver proteins into both prokaryotic and eukaryotic cells, exploiting thermal vesiculation. This method allows to internalize substantial amounts of proteins, with different molecular weight and conformation, without compromising the structural properties and cell viability. Characterizing proteins in a physiological environment is essential as the environment can dramatically affect the conformation and dynamics of biomolecules as shown by in-cell EPR spectra vs those acquired in buffer solution. Considering its versatility, this method opens the possibility to scientists to study proteins directly in living cells through a wide range of techniques.
•Novel protein delivery method for living prokaryotic and eukaryotic cells.•Fast and simple protocol for protein delivery.•Protocol exploiting thermal vesiculation properties of cells.•In cell cw-EPR experiments in living prokaryotic and eukaryotic cells.
Pore connectivity is a measure of the fraction of pore space (vesicles, voids or cracks) in a material that is interconnected on the system length scale. Pore connectivity is fundamentally related to ...permeability, which has been shown to control magma outgassing and the explosive potential of magma during ascent in the shallowest part of the crust. Here, we compile a database of connectivity and porosity from published sources and supplement this with additional measurements, using natural volcanic rocks produced in a broad range of eruptive styles and with a range of bulk composition. The database comprises 2715 pairs of connectivity C and porosity ϕ values for rocks from 35 volcanoes as well as 116 products of experimental work. For 535 volcanic rock samples, the permeability k was also measured. Data from experimental studies constrain the general features of the relationship between C and ϕ associated with both vesiculation and densification processes, which can then be used to interpret natural data. To a first order, we show that a suite of rocks originating from effusive eruptive behaviour can be distinguished from rocks originating from explosive eruptive behaviour using C and ϕ. We observe that on this basis, a particularly clear distinction can be made between scoria formed in fire-fountains and that formed in Strombolian activity. With increasing ϕ, the onset of connectivity occurs at the percolation threshold ϕc which in turn can be hugely variable. We demonstrate that C is an excellent metric for constraining ϕc in suites of porous rocks formed in a common process and discuss the range of ϕc values recorded in volcanic rocks. The percolation threshold is key to understanding the onset of permeability, outgassing and compaction in shallow magmas. We show that this threshold is dramatically different in rocks formed during densification processes than in rocks formed in vesiculating processes and propose that this value is the biggest factor in controlling the evolution of permeability at porosities above ϕc.
•Connectivity can be used to distinguish between subsets of volcanic materials.•Connectivity allows to identify the percolation threshold ϕc of volcanic rocks.•Pore connectivity evolves differently as a result of vesiculation and cracking.•Shear-deformation reduces the percolation threshold during vesiculation.•Connectivity contains information about permeability at porosities close to ϕc.
Volcanic eruptions are driven by the growth of gas bubbles in magma. The timing and rate of bubble growth are important because they determine whether enough gas pressure can develop to fragment the ...melt. Bubbles grow in response to decompression and diffusive transport of dissolved volatiles (predominantly H2O) that exsolve into the bubbles. Growth is resisted by the viscosity of the melt. Both melt viscosity and H2O diffusivity have non-linear dependence on the concentration of H2O dissolved in the melt, which necessitates a numerical approach to modelling bubble growth. Several bubble growth models have previously been published and applied, but none of them has been validated against continuous, in situ experimental data or provided as a user-friendly tool. Here we present a numerical bubble growth model, implemented in MATLAB, which allows for arbitrary temperature and pressure pathways, and accounts for the impact of spatial variations in dissolved H2O concentration on viscosity and diffusivity. We validate the model against two sets of experimental data: (1) New continuous data for gas-volume fraction as a function of time, collected using optical dilatometry of vesiculating hydrous obsidian samples which were heated from 930 °C to 1000 °C at atmospheric pressure. This dataset captures isobaric, isothermal bubble growth under strongly disequilibrium conditions. (2) Discrete data from published decompression experiments at 825 °C and pressures from 200 MPa to ~5 MPa with decompression rates from 0.1 MPa s−1 to 10 MPa s−1. These experiments represent isothermal, decompression-driven bubble growth spanning equilibrium to strongly disequilibrium conditions. The numerical model closely reproduces the experimental data across all conditions, providing validation against contrasting bubble growth scenarios. The validated model has a wide range of potential volcanological applications, including forward modelling of bubble growth phenomena, and inverse modelling to reconstruct pressure–temperature–time pathways from textures and volatile contents of eruptive products.
•Flexible and general numerical model for bubble growth in magma available for download•Model validated against in-situ and decompression experiments across a range of disequilibrium conditions•Model suitable for predicting bubble growth under arbitrary pressure-temperature-time pathways•Extendable and user-configurable to include material models (solubility, diffusivity, viscosity) for different compositions
Soybean is a globally important legume crop which is highly sensitive to drought. The identification of genes of particular relevance for drought responses provides an important basis to improve ...tolerance to environmental stress. Chloroplast Vesiculation (CV) genes have been characterized in Arabidopsis and rice as proteins participating in a specific chloroplast-degradation vesicular pathway (CVV) during natural or stress-induced leaf senescence. Soybean genome contains two paralogous genes encoding highly similar CV proteins,
and
. In this study, we found that expression of
was differentially upregulated by drought stress in soybean contrasting genotypes exhibiting slow-wilting (tolerant) or fast-wilting (sensitive) phenotypes.
reached higher induction levels in fast-wilting plants, suggesting a negative correlation between
gene expression and drought tolerance. In contrast, autophagy (ATG8) and ATI-PS (ATI1) genes were induced to higher levels in slow-wilting plants, supporting a pro-survival role for these genes in soybean drought tolerance responses. The biological function of soybean CVs in chloroplast degradation was confirmed by analyzing the effect of conditional overexpression of CV2-FLAG fusions on the accumulation of specific chloroplast proteins. Functional specificity of
and
genes was assessed by analyzing their specific promoter activities in transgenic Arabidopsis expressing GUS reporter gene driven by
or
promoters.
promoter responded primarily to abiotic stimuli (hyperosmolarity, salinity and oxidative stress), while the promoter of
was predominantly active during natural senescence. Both promoters were highly responsive to auxin but only
responded to other stress-related hormones, such as ABA, salicylic acid and methyl jasmonate. Moreover, the dark-induced expression of
, but not of
, was strongly inhibited by cytokinin, indicating similarities in the regulation of
to the reported expression of Arabidopsis and rice CV genes. Finally, we report the expression of both
and
genes in roots of soybean and transgenic Arabidopsis, suggesting a role for the encoded proteins in root plastids. Together, the results indicate differential roles for
and
in development and in responses to environmental stress, and point to
as a potential target for gene editing to improve crop performance under stress without compromising natural development.
In red blood cell (RBC) diseases, the spleen contributes to anemia by clearing the damaged RBCs, but its unique ability to mechanically challenge RBCs also poses the risk of inducing other pathogenic ...effects. We have analyzed RBCs in hereditary spherocytosis (HS) and hereditary elliptocytosis (HE), two typical examples of blood disorders that result in membrane protein defects in RBCs. We use a two-component protein-scale RBC model to simulate the traversal of the interendothelial slit (IES) in the human spleen, a stringent biomechanical challenge on healthy and diseased RBCs that cannot be directly observed in vivo. In HS, our results confirm that the RBC loses surface due to weakened cohesion between the lipid bilayer and the cytoskeleton and reveal that surface loss may result from vesiculation of the RBC as it crosses IES. In HE, traversing IES induces sustained elongation of the RBC with impaired elasticity and fragmentation in severe disease. Our simulations thus suggest that in inherited RBC disorders, the spleen not only filters out pathological RBCs but also directly contributes to RBC alterations. These results provide a mechanistic rationale for different clinical outcomes documented following splenectomy in HS patients with spectrin-deficient and ankyrin-deficient RBCs and offer insights into the pathogenic role of human spleen in RBC diseases.
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