Solute Exchange Research Articles

Instantaneous extracellular solution exchange for concurrent evaluation of membrane permeability of single cells.

The osmotic stress imposed on microorganisms by hypotonic conditions is perceived to regulate water and solute flux via cell membranes, which are crucial for survival. Some cells that fail to perceive osmotic stress die because this results in the rupture of the cell membrane. The flux through the membrane is characterized by the membrane permeability, which is measured using a stopped-flow apparatus in response to a millisecond-order osmolarity change. However, the obtained data are an ensemble average of each cell response. Additionally, the measurement of permeability, considering cellular viability, contributes to a more accurate evaluation of osmoadaptation. Here, we present a novel on-chip instantaneous extracellular solution exchange method using an air-liquid interface. The presented method provides a concurrent evaluation at the single-cell level in response to a millisecond-order osmotic shock, considering cellular viability by solution exchange. This method utilizes a liquid bridge with a locally formed droplet on the surface of a micropillar fabricated inside a microchannel. We evaluated a solution exchange time of 3.6 ms and applied this method to Synechocystis PCC 6803 under two different osmolarity conditions. The live/dead ratio of 1 M to 0.5 M osmotic down shock condition was 78.8/21.2% while that of 1 M to 0.25 M osmotic down shock condition was 40.0/60.0%. We evaluated the water permeability of two groups: cells that were still live before and after osmotic shock (hereafter named cell type 1), and cells that were live before but were dead 10 minutes after osmotic shock (hereafter named cell type 2). The results indicated that the water permeability of cell type 2 was higher than that of cell type 1. The results obtained using the presented methods confirmed that the effect of osmotic stress can be accurately evaluated using single-cell analysis.

Metal-cation-induced shifts in thiolate redox and reduced sulfur speciation.

Sulfur-containing anions (e.g. thiolates, polysulfides) readily exchange in solution, making control over their solution speciation and distribution challenging. Here, we demonstrate that different redox-inactive alkali, alkaline earth, and transition metals (Li+, Na+, K+, Mg2+, Ca2+, Zn2+, and Cd2+) shift the equilibria of sulfur catenation or sulfur reduction/oxidation between thiolate, polysulfanide, and polysulfide anions in acetonitrile solution. The thermodynamic factors that govern these equilibria are examined by identification of intermediate metal thiolate and metal polysulfide species using a combination of NMR spectroscopy, electronic absorption spectroscopy, and mass spectrometry. Electrochemical measurements demonstrate that the metal cation of the electrolyte modulates both sulfur reduction and thiolate oxidation potentials. DFT calculations suggest that the changes in equilibria are driven by stronger covalent interactions between polysulfide anions and more highly charged cations.

Specific constructive solution of a log house from southwest Serbia

The Dinaric log cabin was the dominant form of residential house in the Dinaric mountains region in the Balkans. In the valley of the Uvac River, in southwest Serbia, a structural solution with preserved cornice was recorded, which differs significantly from the solution of the Dinaric log cabin. It is characterized by a gable roof (instead of a four-gable one), and the beam on the ridge rests on a specially built structure consisting of a console and a rod. This solution indicates that there was an exchange of construction solutions in the Balkans and Europe, that they were transferred by builders, travellers or settlers. A similar construction solution is applied in Austria, Switzerland and Russia.

Effects of sediment disturbance by the heart urchin <i>Echinocardium cordatum</i> on the sediment–seawater solute exchange: An exclusion experiment

<p>Spatangoid heart urchins are dominant bioturbators in marine soft-sediment ecosystems worldwide. Their repeated sediment reworking prevents biogeochemical sediment stratification and colonization by other species, with implications for sedimentary reaction processes that affect the local sediment–seawater solute exchange. Here, we used a simple exclusion experiment to investigate how a subtidal <italic>Echinocardium cordatum</italic> population (18.2 ± 6.7 individuals m<sup>−2</sup>), foraging at an individual speed of ~45 cm per day affects the sediment–seawater solute exchange. To do so, we removed all heart urchins from eight one-meter-diameter areas of the 10-m deep seafloor of Man O'War Bay, Hauraki Gulf, New Zealand, and prevented recolonization and thus sediment reworking for 56 days. Subsequently, we measured the sediment–seawater exchange of O<sub>2</sub>, NO<sub>3</sub><sup>–</sup>, NO<sub>2</sub><sup>–</sup>, NH<sub>4</sub><sup>+</sup>, and N<sub>2</sub> both within and outside the exclusion areas, under light or dark conditions, and found no difference. The absence of a legacy effect of foraging <italic>E. cordatum</italic> after their removal suggests that, at least in this habitat, their influence on the sediment–seawater solute exchange may be limited to sediment being displaced in the immediate surrounding of the urchin. This unexpected result underlines the importance of evaluating the influence of bioturbators on the sediment–seawater solute exchange in the context of local environmental conditions, animal behavior, and population characteristics.</p>

Strategies for optimizing partnership: workshop on teamwork for teachers and parents in early childhood education

ABSTRACT One of the keys to early childhood education program success is providing opportunities for teachers and parents to create effective partnerships. However, teachers often face difficulties in involving parents in parenting activities. The authors employed the qualitative case study method to explore teachers’ and parents’ collaboration in the context of early childhood education. The authors conducted observations, interviews, and field notes in collecting the data. The data were analysed thematically using qualitative data analysis. The analysis focuses on the implementation of a three-stage partnership workshop involving teachers and parents. The findings of this study demonstrate that workshops focused on teamwork, which aim to enhance collaboration between teachers and parents, have been found to be successful in promoting the exchange of knowledge, skills, experiences, challenges, and solutions pertaining to the provision of educational services that are pertinent to child development. Consequently, these workshops have the potential to foster a harmonious partnership between teachers and parents.

At the limits of bisphosphonio-substituted stannylenes.

Donor stabilization of Sn(II) and Pb(II) halides with 1,1'-ferrocenylene bridged bisphosphanes has been explored for Fe(C5H4P(C6H5)2)2 (dppf), and Fe(C5H4PH(C4H9))2. These bisphosphanes are reacted with SnBr2 and PbCl2 with and without additional Lewis acid (AlCl3) forming acyclic and cyclic donor adducts from which the latter represent bisphosphoniotetrylenes. Since dynamic exchange in solution is observed, characterization includes solution and solid-state NMR in addition to SC-XRD, amended by DFT calculations.

Nb-Based Oxides As High Power Negative Electrode Materials

Today, one of the main challenges of lithium-ion batteries is to have the ability to charge faster and to provide high power during longer periods, thus allowing a larger development of intermittent electric power sources [1]. The actual negative electrode materials (graphite and silicon mainly) cannot sustain such high rate capabilities. In this work, we are therefore investigated some materials of the plentiful family of niobium-based oxides. A presentation of old and interesting structures will be briefly reviewed. As an example, the case of KTiNbO5 will be discussed and proposed as efficient negative electrode materials for next generation of lithium ion batteries.The layered KTiNbO5 with a two-dimensional framework represents a playground to produce a large range of closely related phases.[2] The protonated HTiNbO5 analogue is obtained by ion exchange in acidic solution and it preserves a layered structure with a smaller interlayer distance. After dehydration of HTiNbO5 at 400°C, the so-obtained Ti2Nb2O9 phase displays a 2D arrangement with empty channels unlike tunnels of H(K)TiNbO5.In this work, all the synthesized phases were studied as negative electrode materials in lithium-ion batteries. Tested in 1M LiPF6 in EC/DMC between 1.0V and 3.0V vs Li/Li+, these phases have shown different electrochemical behaviors. When HTiNbO5 exhibits a typical plateau during the charge/discharge experiment corresponding to a biphasic phenomenon, lithiation of Ti2Nb2O9 is governed by a solid—solution mechanism. For a better understanding of the charge storage mechanism, we have combined electrochemical experiments with in situ XRD measurements. We have shown that multielectron redox and corner/edge sharing system of Ti/Nb octaedra are at the origin of an interesting capacity of more than 100 mAh.g-1 at a rate of 0.2 A.g-1. A good observed cyclability (< 500 cycles) is in accordance with in situ XRD results showing a reversible behavior of the structure during cycling. Another synthesis method, using Chimie Douce techniques, leads to nanoparticules for both HTiNbO5 and Ti2Nb2O9 and allows an increase of the electrochemical performance of these materials. References : [1] Choi, C. et al, Nature Rev. Mat. 5, 5-19 (2020).[2] A. D. Wadsley, Acta Cryst. 623, 17-41 (1964).

Glymphatic dysfunction in the pathogenesis of neurodegenerative diseases and pathological aging

Recently, the concept of the glymphatic system as a highly organized perivascular network has been formed, which by hydrodynamic approach, with the key participation of aquaporin-4 as a central molecule, connects the cerebrospinal fluid with the lymphatic vessels of the meninges through the brain interstitium. The latest scientific works demonstrates the potential role of glymphatic dysfunction in the development of neurodegeneration and pathological aging. Although the precise molecular mechanisms of glymphatic pathway function have not yet been fully characterized, the critical processes underlying cerebral solute transport and clearance of amyloid and metabolites have been largely elucidated. The complex interaction between a number of age-associated factors, including cellular aging, disturbances in the sleep-wake cycle with changes in sleep architecture and quality, low-grade systemic inflammation, and the development of concomitant diseases, determines not only life expectancy in general, but also forms the basis of healthy and unhealthy aging the brain in particular. Imbalances in homeostatic functions, changes in the activity of glymphatic clearance and the blood-brain barrier that support the exchange of fluid and solutes in cerebral tissue, which can be observed both normally with physiological aging and with the development of neuropathology, have longitudinal consequences ranging from disruption of synaptic signal transmission to onset of neurodegenerative processes. This review analyzes the current scientific information in this area of research, details the features of the perivascular glial-mediated transport system, and discusses how its dysfunction plays a fundamental role in the pathological accumulation of metabolites during aging, the development of age-associated changes in the brain, and the progression of neurodegenerative diseases.

A compact, high-throughput semi-automated embryo vitrification system based on hydrogel

Research questionWhat is the efficiency and efficacy of the novel Biorocks semi-automated vitrification system, which is based on a hydrogel? DesignThis comparative experimental laboratory study used mouse model and human day 6 blastocysts. Mouse oocytes and embryos were quality assessed post-vitrification. ResultsThe Biorocks system successfully automated the solution exchanges during the vitrification process, achieving a significantly improved throughput of up to 36 embryos/oocytes per hour. Using hydrogel for cryoprotective agent delivery, 12 vessels could be processed simultaneously, fitting comfortably within an assisted reproductive technology (ART) workstation. In tests involving the cryopreservation of oocytes and embryos, the system yielded outcomes equivalent to the manual Cryotop method. For example, the survival rate for mouse oocytes was 98% with the Biorocks vitrification system (n = 46) and 95% for the manual Cryotop method (n = 39), of which 46% and 41%, respectively, progressed to blastocysts on day 5 after IVF. CC-grade day 6 human blastocysts processed with the Biorocks system (n = 39) were associated with a 92% 2 h re-expansion rate, equivalent to the 90% with Cryotop (n = 30). The cooling/warming rates achieved by the Biorocks system were 31,900°C/minute and 24,700°C/minute, respectively. Oocyte quality was comparable or better post-vitrification for Biorocks than Cryotop. ConclusionsThe Biorocks semi-automated vitrification system offers enhanced throughput without compromising the survival and developmental potential of oocytes and embryos. This innovative system may help to increase the efficiency and standardization of vitrification in ART clinics. Further investigations are needed to confirm its efficacy in a broader clinical context.

Hypothesis and theory: Do trees “release the tension” in rainwater? Surface tension reduction in throughfall and stemflow from urban trees

Knowledge of the processes and impacts associated with the canopy’s partitioning of rainfall into stemflow (water that drains to the base of tree stems) and throughfall (water that drips through gaps and from canopy surfaces) has expanded in recent years. However, the effect of canopy interactions on the fundamental physical properties of rainwater as it travels through the canopy to the soil, particularly surface tension, remains understudied. To discuss specific hypotheses within this context and their relevance to ecohydrological theory, the surface tension of rainwater samples was examined directly. Over a period of 9 months, open rainwater, throughfall and stemflow samples were collected during 20 storms from 12 study trees located in Secrest Arboretum (about 2.5 km outside Wooster, Ohio). Study trees were selected to highlight a range of canopy characteristics, with each tree being from a unique deciduous species. Surface tension was measured using pendant drop goniometry, and measurements were analyzed for variation across study trees and correlation with event air temperature and rain intensity. In general, surface tension was reduced in throughfall and stemflow compared to measurements made for event rainwater, with median surface tension changes of −0.446 mN m−1 and −0.595 mN m−1 for throughfall and stemflow, respectively. The extent of this reduction varied among study trees (with changes as great as −6.5 to −5.5 mN m−1), and storm event characteristics were directly and indirectly correlated with surface tension changes in select cases. Hypothetically, a number of mechanisms may account for the observed reduction (and variation in this reduction) in surface tension, including differences in tree surface properties, canopy microenvironments, and microbiomes, and each warrant further research. Testing these hypotheses may advance broader ecohydrological theory as surface tension changes will influence wetting, absorption, and solute exchange processes within the canopy which, in turn, may affect related surface processes.

Comparison of IVIM MRI measures of brain fluid transport against contrast‐enhanced MRI in the setting of sleep deprivation

AbstractBackgroundGlymphatic exchange of interstitial solutes may underlie the observed clinical association between sleep, aging, and Alzheimer’s Disease (AD). Furthermore, glymphatic function is currently primarily measured by contrast‐based (CE) MRI, limiting its clinical utility. In this work we test a wearable device to assess sleep architecture and a diffusion‐based intravoxel incoherent motion (IVIM) protocol to detect sleep‐related changes in the glymphatic system at two sites.Method Site 1: We recruited 13 participants (age = 62±3 yrs. old, 4F) and assessed them prior to and following overnight sleep and sleep deprivation. Sleep efficiency, relative slow delta power, N2, N3, and REM durations were measured with the wearable device. Using CE‐MRI, delayed contrast enhancement in the subarachnoid (SASe) was measured at ∼4 hrs after contrast injection to assess brain parenchymal solute clearance during a second recovery sleep opportunity. For contrast‐free MRI, we measured slow subarachnoid CSF flow (D*) in the SAS using IVIM at night and in the morning. Cognitive assessments were conducted in the morning only. Site 2: We conducted an identical sleep/sleep deprivation study (N = 10, age = 54±5 yrs. old, 9F), but without CE MRI. We tested the correlation between SASe and D*. Next, we compared changes in D* between a night of sleep and sleep deprivation and tested associations with sleep parameters.Result A. Change in D* after sleep or awake opportunity was significantly associated with SASe (p = 0.05) Greater SAS D* was associated with lesser contrast in the SAS. B. Although not significant, D* reproducibly decreases with sleep deprivation and remains unchanged after sleep. C‐D. Differences in D* during sleep were significantly associated with slow wave spindle number (p = 0.03) and N3 duration (p = 0.04). E. D* measurement concurrent with PVT administrations showed that while greater D* after staying awake was associated with longer reaction times, greater D* after a night of sleep was associated with shorter reaction times.ConclusionWith a wearable device, remote sleep assessment was successfully performed. IVIM‐derived D* was associated with CE MRI measures in the SAS providing a non‐invasive alternative to study brain fluid transport. D* showed associations with sleep parameters as well as sleep‐associated cognition.

Effects of Periodic Fluctuation of Water Level on Solute Transport in Seasonal Lakes in Poyang Floodplain System

AbstractSeasonal lakes appear in floodplain systems due to the seasonal variation of water level of rivers or main lakes and play an important ecological function. Previous studies have focused on exchange flux between the surface water and groundwater in seasonal lakes, but the process of solute transport at the sediment‐water interface under the effect of seasonal water level fluctuations remains unclear. In this study, laboratory flume experiments and numerical simulations were conducted to investigate non‐reactive solute transport and exchange in a seasonal lake under effects of hydrological connectivity, water level amplitude, sediment permeability and solute source. The results show that the recharge pattern between seasonal lakes and rivers or main lakes is determined by the seasonal water level. The solute transports from the groundwater of seasonal lakes to the main lake during the dry season, while the reverse applies during the wet season. The perennial hydrological isolation increases the concentration in the overlying water and pore water of the seasonal lake by 20.5% and 28.7%, respectively. The solute concentration in the overlying water and pore water of the seasonal lake decreases by 55.2% and 51.5%, respectively, when solute source occurs in the main lake compared with that occurs in the seasonal lake. The amplification of water level amplitudes leads to an increase of 6.46% and 10.55% in the solute concentration drop from the overlying water, respectively. These findings contribute to improving water resource utilization and protecting aquatic ecological environment in floodplain systems.

Cu-doped bioactive glass with enhanced in vitro bioactivity and antibacterial properties

This work aimed to optimize, produce and characterize Cu-doped bioactive glasses which are antibacterial without the addition of antibiotics obtained via ion exchange in an aqueous solution. According to morphological, compositional and structural analyses, 0.001 M was selected as the most optimal concentration of the ion exchange solution. The doped glass was then compared to the undoped one to investigate the effect of Cu-doping on the glass surface composition and bioactivity. Cu-doping was found to enhance the bioactivity kinetics and the following hydroxyapatite formation, evidenced by X-ray diffraction, energy dispersive X-ray spectroscopy, and zeta potential measurements. Besides that, the zeta potential titration measurements confirmed that the Cu-doping did not alter the surface chemical stability of the glass both in the inflammatory and physiological pH range. Moreover, the leaching ability of Cu2+-ions, both in physiological and inflammatory-mimicking conditions, was measured, followed by an in-depth study of the antibacterial properties, using two protocols to distinguish between the antiadhesive, antibacterial, and antibiofilm effects. For both protocols, a reduction of metabolic activity and Colony-Forming Unit after 24 h against Staphylococcus aureus Multi-Drug resistance strain was evidenced. These results showed that Cu-doped glass could show potential as a bioactive and antibacterial surface for bone surgery applications.

How to Tailor Immersion Tin Plating for IC Substrate Applications

Immersion tin finishes are widely used in the printed circuit board (PCB) industry. They provide reliable connections with high solder joint reliability compared to other final finishes. Due to the direct intermetallic formation between copper and solder, the intermetallic compounds (IMC) formed during the assembly exhibit ductile properties and are less prone to brittle fractures than e.g. solder joints formed with nickel finishes such as electroless nickel/immersion gold (ENIG). With the given high solder joint reliability, the immersion tin finish therefore is one of the first choices for the application in the IC substrate industry. It provides already a robust and nickel free finish with high process efficiency for lower cost. But due to the trends to increased I/O counts, reduced lines and spaces, improved signal integrity and further lowering the cost in the packaging applications, the adjustment of the immersion tin process became necessary to cope with the changed technology demands. Topic of this paper is the introduction of an immersion tin plating process specifically designed for IC substrate applications. It is focusing on three major aspects: the plating process itself, the equipment solutions to realize best quality control and process monitoring and finally the performance of the final finish itself in comparison to other common end finishes. The trend to more and more reduced lines and spaces requires the adjustment of the plating chemistry. A good solution flow needs to be ensured to prevent excessive attack of the copper tracks or disproportionate solder mask undercut. The study presented here compares conventional immersion tin plating solutions with a modified process for IC substrate plating. It shows, how the variation of solution viscosity and flow can impact the copper attack and solder mask undercut. Due to the better solution exchange and adjusted plating conditions, the copper dissolution can be significantly reduced and the attack to the solder mask can be minimized. The complimentary horizontal plating equipment supports the specific properties of the plating electrolyte. Insights to the equipment design and adjustments are being discussed to identify the best conditions for the immersion tin plating on fine structures with highest quality demands. Finally, the tin deposit is investigated and compared to conventional immersion tin as well as to other standard finishes such as ENIG, ENEPIG (Electroless Nickel, electroless Palladium, Immersion gold) or OSP (organic solder preservative) regarding its solder wetting performance and solder joint reliability. It can be concluded that the immersion tin finish designed for small L/S applications can validate the benefits known from the long years’ experience with immersion tin. The layer shows comparable solder wetting properties to conventional immersion tin finishes and excellent solder joint reliability when compared to ENIG or OSP with better performance even after thermal aging. The risk for typical IC substrate related defects such as excessive copper corrosion or solder mask undercut as well as missing bumps is lowered compared to the conventional process. The main focus of this paper is to show, that the high demands in substrate industry can be tackled when the plating solution and plating equipment are designed and adjusted to the new requirements in a coordinated approach so that they can complement each other.

Knowledge sharing in global governance: a path in public goods delivery

ABSTRACT The exchange of knowledge in development cooperation can help overcome common challenges while providing collective solutions. Country, regional and global platforms play a crucial role to facilitate development cooperation at both national and international level, but there is a lack of knowledge on their structure and operationalisation. The aim of this paper is to fill this knowledge gap to assess how global platforms can contribute to bridge the establishment of national priorities with the provision of global public goods. By way of a documentary analysis and semi-structured interviews, the study examines the case of the South-South Galaxy, a platform created by the United Nations Office for South-South Cooperation to promote the exchange of solutions among all Southern knowledge sharing platforms. The main results find that each node of knowledge sharing works to build a shared understanding of good practices on the SDGs and make this knowledge universally accessible.

Grand-canonical molecular dynamics simulations powered by a hybrid 4D nonequilibrium MD/MC method: Implementation in LAMMPS and applications to electrolyte solutions.

Molecular simulations in an open environment, involving ion exchange, are necessary to study various systems, from biosystems to confined electrolytes. However, grand-canonical simulations are often computationally demanding in condensed phases. A promising method [L. Belloni, J. Chem. Phys. 151, 021101 (2019)], one of the hybrid nonequilibrium molecular dynamics/Monte Carlo algorithms, was recently developed, which enables efficient computation of fluctuating number or charge density in dense fluids or ionic solutions. This method facilitates the exchange through an auxiliary dimension, orthogonal to all physical dimensions, by reducing initial steric and electrostatic clashes in three-dimensional systems. Here, we report the implementation of the method in LAMMPS with a Python interface, allowing facile access to grand-canonical molecular dynamics simulations with massively parallelized computation. We validate our implementation with two electrolytes, including a model Lennard-Jones electrolyte similar to a restricted primitive model and aqueous solutions. We find that electrostatic interactions play a crucial role in the overall efficiency due to their long-range nature, particularly for water or ion-pair exchange in aqueous solutions. With properly screened electrostatic interactions and bias-based methods, our approach enhances the efficiency of salt-pair exchange in Lennard-Jones electrolytes by approximately four orders of magnitude, compared to conventional grand-canonical Monte Carlo. Furthermore, the acceptance rate of NaCl-pair exchange in aqueous solutions at moderate concentrations reaches about 3% at the maximum efficiency.

Compromised junctional integrity phenocopies age-dependent renal dysfunction in Drosophila Snakeskin mutants.

Transporting epithelia provide a protective barrier against pathogenic insults while allowing the controlled exchange of ions, solutes and water with the external environment. In invertebrates, these functions depend on formation and maintenance of 'tight' septate junctions (SJs). However, the mechanism by which SJs affect transport competence and tissue homeostasis, and how these are modulated by ageing, remain incompletely understood. Here, we demonstrate that the Drosophila renal (Malpighian) tubules undergo an age-dependent decline in secretory capacity, which correlates with mislocalisation of SJ proteins and progressive degeneration in cellular morphology and tissue homeostasis. Acute loss of the SJ protein Snakeskin in adult tubules induced progressive changes in cellular and tissue architecture, including altered expression and localisation of junctional proteins with concomitant loss of cell polarity and barrier integrity, demonstrating that compromised junctional integrity is sufficient to replicate these ageing-related phenotypes. Taken together, our work demonstrates a crucial link between epithelial barrier integrity, tubule transport competence, renal homeostasis and organismal viability, as well as providing novel insights into the mechanisms underpinning ageing and renal disease.

Solar-powered MXene biopolymer aerogels for sorption-based atmospheric water harvesting

Solar energy-powered sorption-based atmospheric water harvesting (AWH) is an innovative approach to acquiring fresh water in water-stressed areas. Here, a method was provided for combining a polyacrylamide/chitosan skeleton and an MXene solar absorber to produce a solar-powered hygroscopic polymer aerogel for atmospheric water harvesting (AWH). Solution exchange and lyophilization were combined in the preparation method. The experiments showed that the porous aerogels enabled high-performance AWH. At 90% relative humidity and 25 °C, the water sorption capacity reached 5.0 g·g−1. At a light intensity of 1 kW·m−2 for 4 h, almost all of the adsorbed water (>98%) was released due to photothermal conversion. The tensile strength exceeded 1.3 MPa. Additionally, the water collection capacity under unstable outdoor conditions was 0.92 L·kg−1 (under unstable natural light (0.11–1.01 kW ·m−2)). This method offers a straightforward, efficient, and useful solution, even under adverse environmental conditions.

Pathogenic role of autoantibodies at the ependyma in autoimmune disorders of the central nervous system.

Ependymal cells make up the epithelial monolayer that lines the brain ventricles and the spinal cord central canal that are filled with cerebrospinal fluid. The ependyma has several functions, including regulating solute exchange between the cerebrospinal fluid and parenchyma, controlling microcirculation of cerebrospinal fluid via coordinated ciliary beating, and acting as a partial barrier. Dysregulation of these functions can lead to waste clearance impairment, cerebrospinal fluid accumulation, hydrocephalus, and more. A role for ependymal cells in a variety of neurological disorders has been proposed, including in neuromyelitis optica and multiple sclerosis, two autoimmune demyelinating diseases of the central nervous system, where periventricular damage is common. What is not known is the mechanisms behind how ependymal cells become dysregulated in these diseases. In neuromyelitis optica, it is well established that autoantibodies directed against Aquaporin-4 are drivers of disease, and it has been shown recently that these autoantibodies can drive ependymal cell dysregulation. We propose a similar mechanism is at play in multiple sclerosis, where autoantibodies targeting a glial cell protein called GlialCAM on ependymal cells are contributing to disease. GlialCAM shares high molecular similarities with the Epstein-Barr virus (EBV) protein EBNA1. EBV has recently been shown to be necessary for multiple sclerosis initiation, yet how EBV mediates pathogenesis, especially in the periventricular area, remains elusive. In this perspective article, we discuss how ependymal cells could be targeted by antibody-related autoimmune mechanisms in autoimmune demyelinating diseases and how this is implicated in ventricular/periventricular pathology.

Complementary effects of sorption and biochemical processing of dissolved organic matter for emerging structure formation controlled by soil texture

AbstractBackgroundPercolating dissolved organic matter (DOM) from the topsoil is considered the main source of subsoil organic carbon (OC) in temperate soils, but knowledge about its influence on OC storage and structure‐forming processes is limited.AimsWe conducted a 30‐day incubation experiment with artificial soils to study the effects of percolating DOM and soil texture on OC turnover and initial structure formation.MethodsArtificial soils with contrasting texture, but identical mineral composition, were used to mimic subsoil conditions, where mineral surfaces free of OM come into contact with percolating DOM. After the incubation, we assessed the solution exchange, OM covers on minerals, microbial community and OC turnover, and aggregate formation and stability.ResultsA higher sand content caused a lower porosity, accompanied by a lower moisture content. In contrast, the OC retention (21% of the OC input), microbial activity, and community size were unaffected by soil texture. The OM covered 10% of the mineral surfaces within an otherwise OC‐free mineral matrix. The formation of large, water‐stable aggregates occurred in all soils, but was pronounced in the clay‐rich soils (58% mass contribution), which also supported a higher mechanical stability of the aggregates.ConclusionsThe initial retention and microbial mineralization of DOM are decoupled from pore sizes and soil solution exchange but are driven by the mineral composition and OC input. The biochemical processing of the percolating DOM can induce large aggregates. Here, the presence of fine mineral particles enhances the formation and mechanical stability of the aggregates, irrespective of their surface charge or sorptive properties.