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•Structure and function of the osmotically inducible protein Y (OsmY) in Escherichia coli.•OsmY interacts with AquaporinZ under high ionic strength conditions, suggesting a connection ...with the response of Escherichia coli to osmotic stress.•Insights into bacterial survival strategies in osmotically diverse environments.•OsmY’s function is dependent on its primary Bacterial OsmY and Nodulation.domain BON1.•OsmY is a key player in facilitating cell volume recovery and adaptation to severe osmotic stress in Escherichia coli and likely other Gram-negative bacteria.
The ability to adapt to osmotically diverse and fluctuating environments is critical to the survival and resilience of bacteria that colonize the human gut and urinary tract. Environmental stress often provides cross-protection against other challenges and increases antibiotic tolerance of bacteria. Thus, it is critical to understand how E. coli and other microbes survive and adapt to stress conditions. The osmotically inducible protein Y (OsmY) is significantly upregulated in response to hypertonicity. Yet its function remains unknown for decades. We determined the solution structure and dynamics of OsmY by nuclear magnetic resonance spectroscopy, which revealed that the two Bacterial OsmY and Nodulation (BON) domains of the protein are flexibly linked under low- and high-salinity conditions. In-cell solid-state NMR further indicates that there are no gross structural changes in OsmY as a function of osmotic stress. Using cryo-electron and super-resolution fluorescence microscopy, we show that OsmY attenuates plasmolysis-induced structural changes in E. coli and improves the time to growth resumption after osmotic upshift. Structure-guided mutational and functional studies demonstrate that exposed hydrophobic residues in the BON1 domain are critical for the function of OsmY. We find no evidence for membrane interaction of the BON domains of OsmY, contrary to current assumptions. Instead, at high ionic strength, we observe an interaction with the water channel, AqpZ. Thus, OsmY does not play a simple structural role in E. coli but may influence a cascade of osmoregulatory functions of the cell.
•The effects of antihypertensive Enalapril were studied in Mytilus galloprovincialis.•Waterborne Enalapril affected the digestive gland of Mytilus galloprovincialis.•An increased haemocytes ...infiltration was observed in the DG of treated mussels.•No changes in both stress-related proteins and oxidative stress markers occurred.
In the last decades, pharmaceuticals have emerged as a new class of environmental contaminants.
Antihypertensives, including angiotensin-converting enzyme (ACE) inhibitors, are of special concern due to their increased consumption over the past years. However, the available data on their putative effects on the health of aquatic animals, as well as the possible interaction with biological systems are still poorly understood.
This study analysed whether and to which extent the exposure to Enalapril, an ACE inhibitor commonly used for treating hypertension and heart failure, may induce morpho-functional alterations in the mussel Mytilus galloprovincialis, a sentinel organism of water pollution. By mainly focusing on the digestive gland (DG), a target tissue used for analysing the effects of xenobiotics in mussels, the effects of 10-days exposure to 0.6 ng/L (E1) and 600 ng/L (E2) of Enalapril were investigated in terms of cell viability and volume regulation, morphology, oxidative stress, and stress protein expression and localization. Results indicated that exposure to Enalapril compromised the capacity of DG cells from the E2 group to regulate volume by limiting the ability to return to the original volume after hypoosmotic stress. This occurred without significant effects on DG cell viability. Enalapril unaffected also haemocytes viability, although an increased infiltration of haemocytes was histologically observed in DG from both groups, suggestive of an immune response. No changes were observed in the two experimental groups on expression and tissue localization of heat shock proteins 70 (HSPs70) and HSP90, and on the levels of oxidative biomarkers.
Our results showed that, in M. galloprovincialis the exposure to Enalapril did not influence the oxidative status, as well as the expression and localization of stress-related proteins, while it activated an immune response and compromised the cell ability to face osmotic changes, with potential consequences on animal performance.
Oocyte cryopreservation is increasingly being used in reproductive technologies for conservation and breeding purposes. Further development of oocyte cryopreservation techniques requires ...interdisciplinary insights in the underlying principles of cryopreservation. This review aims to serve this purpose by: (1) highlighting that preservation strategies can be rationally designed, (2) presenting mechanistic insights in volume and osmotic stress responses associated with CPA loading strategies and cooling, and (3) giving a comprehensive listing of oocyte specific biophysical membrane characteristics and commonly used permeation model equations. It is shown how transport models can be used to simulate the behavior of oocytes during cryopreservation processing steps, i.e., during loading of cryoprotective agents (CPAs), cooling with freezing as well as vitrification, warming and CPA unloading. More specifically, using defined cellular and membrane characteristics, the responses of oocytes during CPA (un)loading were simulated in terms of temperature- and CPA type-and-concentration-dependent changes in cell volume and intracellular solute concentration. In addition, in order to determine the optimal cooling rate for slow programmable cooling cryopreservation, the freezing-induced cell volume response was simulated at various cooling rates to estimate rates with tolerable limits. For vitrification, special emphasis was on prediction of the timing of reaching osmotic tolerance limits during CPA exposure, and the need to use step-wise CPA addition/removal protocols. In conclusion, we present simulations and schematic illustrations that explain the timing of events during slow cooling cryopreservation as well as vitrification, important for rationally designing protocols taking into account how different CPA types, concentrations and temperatures affect the oocyte.
•Membrane permeability determines the cell volume response upon osmotic stress.•Subzero membrane permeability to water determines freezing-induced dehydration.•Simulations reveal the timing and concentrations needed for step-wise CPA loading.
In this review, we argue that several key features of maximal oxygen uptake (VO2max) should underpin discussions about the biological and reductionist determinants of its interindividual variability: ...(i) training‐induced increases in VO2max are largely facilitated by expansion of red blood cell volume and an associated improvement in stroke volume, which also adapts independent of changes in red blood cell volume. These general concepts are also informed by cross‐sectional studies in athletes that have very high values for VO2max. Therefore, (ii) variations in VO2max improvements with exercise training are also likely related to variations in these physiological determinants. (iii) All previously untrained individuals will respond to endurance exercise training in terms of improvements in VO2max provided the stimulus exceeds a certain volume and/or intensity. Thus, genetic analysis and/or reductionist studies performed to understand or predict such variations might focus specifically on DNA variants or other molecular phenomena of relevance to these physiological pathways.
The structures of three racemic double salts of Co(en)3Cl3 (en is ethane‐1,2‐diamine, C2H8N2), namely, bistris(ethane‐1,2‐diamine‐κ2N,N′)cobalt(III) hexaaquasodium(I) heptachloride, ...Co(en)32Na(H2O)6Cl7, bistris(ethane‐1,2‐diamine‐κ2N,N′)cobalt(III) hexaaquapotassium(I) heptachloride, Co(en)32K(H2O)6Cl7, and ammonium bistris(ethane‐1,2‐diamine‐κ2N,N′)cobalt(III) heptachloride hexahydrate, (NH4)Co(en)32Cl7·6H2O, have been determined, and the structural similarities with the parent compound, tris(ethane‐1,2‐diamine‐κ2N,N′)cobalt(III) trichloride tetrahydrate, Co(en)3Cl3·4H2O, are highlighted. All four compounds crystallize in the trigonal space group Pc1. When compared with the parent compound, the double salts show a modest increase in the unit‐cell volume. The structure of the chiral derivative Λ‐Co(en)32Na(H2O)6Cl7 has also been redetermined at cryogenic temperatures (120 K) and the disorder noted in a previous report has been accounted for.
The structures of the isostructural sodium, potassium, and ammonium double salts of Co(en)3Cl3 (en is ethane‐1,2‐diamine) have been determined and, compared with the parent compound, show a modest increase in the unit‐cell volume.
Cells alter their mechanical properties in response to their local microenvironment; this plays a role in determining cell function and can even influence stem cell fate. Here, we identify a robust ...and unified relationship between cell stiffness and cell volume. As a cell spreads on a substrate, its volume decreases, while its stiffness concomitantly increases. We find that both cortical and cytoplasmic cell stiffness scale with volume for numerous perturbations, including varying substrate stiffness, cell spread area, and external osmotic pressure. The reduction of cell volume is a result of water efflux, which leads to a corresponding increase in intracellular molecular crowding. Furthermore, we find that changes in cell volume, and hence stiffness, alter stem-cell differentiation, regardless of the method by which these are induced. These observations reveal a surprising, previously unidentified relationship between cell stiffness and cell volume that strongly influences cell biology.
Abstract
Rapid biosynthesis of abscisic acid (ABA) in the leaf, triggered by a decrease in cell volume, is essential for a functional stomatal response. However, it is not known whether rapid ...biosynthesis of ABA is also triggered in other plant tissues. Through the application of external pressure to flower, root, and leaf tissues, we test whether a reduction in cell volume can trigger rapid increases in ABA levels across the plant body in two species, Solanum lycopersicum and Passiflora tarminiana. Our results show that, in contrast to rapid ABA synthesis in the leaf, flower and root tissue did not show a significant, increase in ABA level in response to a drop in cell volume over a short time frame, suggesting that rapid ABA biosynthesis occurs only in leaf, not in flower or root tissues. A gene encoding the key, rate-limiting carotenoid cleavage enzyme (9-cis-epoxycarotenoid dioxygenase, NCED) in the ABA biosynthetic pathway in S. lycopersicum, NCED1, was upregulated to a lesser degree in flowers and roots compared with leaves in response to applied pressure. In both species, floral tissues contained substantially lower levels of the NCED substrate 9'-cis-neoxanthin than leaves, and this ABA precursor could not be detected in roots. Slow and minimal ABA biosynthesis was detected after 2 h in petals, indicating that floral tissue is capable of synthesizing ABA in response to sustained water deficit. Our results indicate that rapid ABA biosynthesis predominantly occurs in the leaves, and not in other tissues.
•The response of astrocytes to injury is a major determinant of the outcome after stroke.•In the acute phase, reactive astrocytes are neuroprotective.•In the post-acute and chronic phase, astrocytes ...act as both positive and negative regulators of neural plasticity.•Modulation of astrocyte function at this later stage appears as an attractive strategy to improve functional outcome.•Astrocyte intermediate filament (nanofilament) proteins may represent the right target for this objective, and the complement system may be at least one of the suitable bullets to hit it.
Stroke is an acute insult to the central nervous system (CNS) that triggers a sequence of responses in the acute, subacute as well as later stages, with prominent involvement of astrocytes. Astrocyte activation and reactive gliosis in the acute stage of stroke limit the tissue damage and contribute to the restoration of homeostasis. Astrocytes also control many aspects of neural plasticity that is the basis for functional recovery. Here, we discuss the concept of intermediate filaments (nanofilaments) and the complement system as two handles on the astrocyte responses to injury that both present attractive opportunities for novel treatment strategies modulating astrocyte functions and reactive gliosis.
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