Solute Movement Research Articles

Statistical method for a hydraulic conductivity estimate using empirical formulas

Sediment's hydraulic conductivity is one of the key inputs for estimating solute and water movement in a vadose zone. Laboratory and field measurements are time consuming and subject to substantial inaccuracies. Thus numerous empirical formulas have been adopted to predict hydraulic conductivity from measurable soil properties such as grain size distribution, soil temperature or bulk density. The objective of this study was twofold: (1) assess the hydraulic conductivities calculated from empirical formulas and (2) develop a simple method to estimate hydraulic conductivities for clayey sand sediments. Using sediment samples extracted from irrigation canals in Zitny Ostrov, Southern Slovakia, we evaluated fourteen empirical formulas. Three sets of parameters were assessed using common statistical methods. The sets included computed hydraulic conductivities, logarithmically transformed hydraulic conductivities, and measured values of hydraulic conductivities. Field measurements and laboratory investigations of hydraulic conductivities were performed to supplement our empirical calculations. The three sets of parameters were compared and formed the foundation for developing an original regression equation: Ksat me = 0.019 (LTKsat) 2 + 0.183 (LTKsat) + 4.863an equation that captures the variables with reasonable agreement. The logarithmically transformed and measured values correlated, yielding R2 = 0.945. Thus, the measured values validated our regression equation.

Land use and soil types affect macropore network, organic carbon and nutrient retention, Lithuania

Quantifying the macropore structure of a soil is critical for understanding plant growth and the movement of water or solutes in the soil. X-ray computed tomography was implemented for macroporosity investigation in the profiles of Cambisol (grassland), Retisol (forest, arable land) and Luvisol (forest). In this study, we explored soil macropore network in relation to macropore structure, soil organic carbon, total nitrogen, total phosphorus, total potassium, and bulk density.Cambisol, Luvisol and Retisol had a heterogeneous architecture of the pore space with an abundance of macropores (2–11% for the upper horizons and to 1.5–3.2% for the underlying layers). Retisol had higher macroporosity compared to Luvisol, and lower than Cambisol. Soil organic carbon had the highest significant effect on medium and fine macropores in all soil types, irrespective to land use. N-total, P-total and K-total retention depended on medium and fine macropores.Anthropogenic activity in Retisol (conventional tillage) decreased SOC and N-total within the whole profile compared to undisturbed Retisol (forest), while P-total and K-total concentration within the whole profile was higher in the soil of arable land.The concentration of SOC, N-total, P-total and K-total in perennial grassland and forest soil was similar irrespective of soil type. The highest macroporosity and total surface area of macropores within the whole soil profile was in Cambisol (grassland).The high concentration of organic matter in forest topsoil layer of Luvisol and Retisol promoted soil podzolization.

Integrated surface-subsurface water and solute modeling of a reclaimed in-pit oil sands mine: Effects of ground freezing and thawing

Study regionAthabasca Oil Sands, Alberta, Canada. Study focusThe upland and wetlands substrate in reclaimed oil sands landforms will be constructed of post-mining materials with an objective of replicating the landscape and hydrology of the surrounding boreal systems. Porewater in these materials contain elevated levels of salts and other solutes. Water quality will govern the success and sustainability of the reclaimed landscape. Tightly coupled water and heat dynamics control water and solute movement in boreal systems. We used three-dimensional integrated surface-subsurface flow and chloride transport models with and without ground freezing-thawing to compare performance of an in-pit oil sands mine currently being reclaimed. New hydrological insights for the regionTransient simulations under wet/dry climate cycles suggest that the reclaimed landform will shed water only during wet years. Annual water balance with and without coupled heat dynamics is identical. However, the three-dimensional representation of ground freeze-thaw results in reduced snowmelt infiltration, summer groundwater table, and solute release during winter. The outcome is increased spring runoff, 20% decrease in chloride mass release over simulated eight-year wet climate cycle and relatively reduced summer runoff. The model results suggest that (1) coupled heat dynamics should be considered for detailed evaluation of reclaimed in-pit landforms at finer time scales, and (2) modeling reclaimed landforms without freeze-thaw provides conservative annual solute release estimates, which is appropriate for coarse site-wide models.

Appearance of claudin-5+ leukocyte subtypes in the blood and CNS during progression of EAE

BackgroundTight junctions (TJs) are membrane specializations characteristic of barrier-forming membranes, which function to seal the aqueous pathway between endothelial cells or epithelial cells and, thereby, obstruct intercellular solute and cellular movement. However, previous work from our laboratory found that claudin-5 (CLN-5), a TJ protein prominent at the blood–brain barrier (BBB), was also detected, ectopically, on leukocytes (CLN-5+) in the blood and central nervous system (CNS) of mice with experimental autoimmune encephalomyelitis (EAE), a neuroinflammatory, demyelinating disease that is a model for multiple sclerosis. CLN-5 was further shown to be transferred from endothelial cells to circulating leukocytes during disease, prompting consideration this action is coupled to leukocyte transendothelial migration (TEM) into the CNS by fostering transient interactions between corresponding leukocyte and endothelial junctional proteins at the BBB.MethodsTo begin clarifying the significance of CLN-5+ leukocytes, flow cytometry was used to determine their appearance in the blood and CNS during EAE.ResultsFlow cytometric analysis revealed CLN-5+ populations among CD4 and CD8 T cells, B cells, monocytes and neutrophils, and these appeared with varying kinetics and to different extents in both blood and CNS. CLN-5 levels on circulating T cells further correlated highly with activation state. And, the percentage of CLN-5+ cells among each of the subtypes analyzed was considerably higher in CNS tissue than in blood, consistent with the interpretation that CLN-5+ leukocytes gain preferred access to the CNS.ConclusionSeveral leukocyte subtypes variably acquire CLN-5 in blood before they enter the CNS, an event that may represent a novel mechanism to guide leukocytes to sites for paracellular diapedesis across the BBB.

Expression of AQP1, AQP3, AQP4 and AQP5 in upper respiratory tract of buffaloes during different seasons

ABSTRACT Aquaporins (AQPs) are channels that mediate the movement of fluid and solute across the cell membrane. During hot season, evaporation through respiratory mucosa is an important mechanism for heat dissipation in buffaloes. AQP-mediated fluid movement in upper respiratory tract of buffaloes is yet to be studied. In the present study, the gene expression of AQP1, AQP3, AQP4 and AQP5 in upper respiratory tract of buffaloes were investigated during summer, spring and winter seasons. During summer, there was higher gene expression of AQP1 in nasal turbinate than winter. AQP1 was mainly localized in endothelial cells of blood capillaries of nasal turbinate. In nasal turbinate, the relative expression of AQP3 was upregulated nonsignificantly during summer and downregulated significantly during winter. The immunolocalization of AQP3 were observed in epithelial layers of nasal turbinate. The relative expression of AQP4 and AQP5 was upregulated during winter and downregulated during summer. During summer, the expression of AQP1, AQP3, AQP4 and AQP5 were downregulated in tracheal mucosa, which indicated their minor role in evaporative water loss in buffaloes. There is a seasonal variation of different AQPs in upper respiratory tract of buffaloes.

ارزیابی عملکرد آبشویی نمک در خاک های یخ زده

The movement of water and solutes have received the attention of many scientific researchers over the past few years. Saline soils contain a high content of salt that is deposited in micropores. Therefore, it is necessary to leaching these soils during a time period when winter ice melting occurs due to the splitting of micropores affected by expansion and contraction resulting from the freezing and melting of water in the soil. The present research studies some different salt leaching methods on soil samples collected from Nazarabad region, Iran in 2016. Two types of saline and conventional water of the region and three different volumes of water in both continuous and alternate modes were used under frozen and non-frozen conditions. The results showed that frozen treatments that were irrigated continuously with conventional water of the region had the best performance as compared to other studied treatments, being feasible during winter in the studied region. .

Dispersion and transport of microplastics in three water-saturated coastal soils

The coastal area is one of the key zones for transport and fate of microplastics (MPs). This study investigated the transport behaviors of different sized MPs in three water-saturated coastal soils, with the aim to explore effects of properties of three different coastal soils on the dispersion and migration of three-sized MPs (0.3, 0.5, and 1 µm). All three-sized MPs had the strongest dispersion in Soil 3 solution, followed by that in Soil 1 solution and then that in Soil 2 solution. The strongest dispersion of MPs in Soil 3 solution was attributed to the lowest ionic strength. Such a high dispersion favored MPs movement in soil solution but readily be sorbed and fixed by rich Fe and Al oxides in Soil 3 solid through strong electrostatic attraction, leading to the lowest transport rate (20.5–41.2%). The high ionic strength in the Soil 1 solution decreased the dispersion of MPs, but the presence of high content of humic acid enhanced the electrostatic repulsion and steric hindrance between MPs and soil particles, resulting in the highest transport ability of MPs in Soil 1 (39.4–72.5%). The large amount of dissolved Ca2+ and Mg2+ in Soil 2 solution favored MPs bridged with fulvic acid, resulting in the highest aggregation of MPs and relatively lower transport ability (34.1–49.6%). Large-sized MPs had higher electrostatic repulsion between the particles, thus increasing the dispersion and transport capacity of MPs in soil. Modeling showed the experiment-consistent results that Soil 3 had the lowest MPs transport after 600 mm of heavy rainfall, with the maximum migration distance of 7.50–10.5 cm, which was smaller than that in Soil 2 (8.10–12.0 cm) and that in Soil 1 (9.00–18.3 cm). These results indicated that MPs transport in coastal soil is significant and soil solution and solid composition plays an important role in the dispersion and transport of MPs, respectively. These findings afforded a great basis for the assessment of the fate and risk of MPs in coastal areas.

DMFO-CD: A Discrete Moth-Flame Optimization Algorithm for Community Detection

In this paper, a discrete moth–flame optimization algorithm for community detection (DMFO-CD) is proposed. The representation of solution vectors, initialization, and movement strategy of the continuous moth–flame optimization are purposely adapted in DMFO-CD such that it can solve the discrete community detection. In this adaptation, locus-based adjacency representation is used to represent the position of moths and flames, and the initialization process is performed by considering the community structure and the relation between nodes without the need of any knowledge about the number of communities. Solution vectors are updated by the adapted movement strategy using a single-point crossover to distance imitating, a two-point crossover to calculate the movement, and a single-point neighbor-based mutation that can enhance the exploration and balance exploration and exploitation. The fitness function is also defined based on modularity. The performance of DMFO-CD was evaluated on eleven real-world networks, and the obtained results were compared with five well-known algorithms in community detection, including GA-Net, DPSO-PDM, GACD, EGACD, and DECS in terms of modularity, NMI, and the number of detected communities. Additionally, the obtained results were statistically analyzed by the Wilcoxon signed-rank and Friedman tests. In the comparison with other comparative algorithms, the results show that the proposed DMFO-CD is competitive to detect the correct number of communities with high modularity.

Nitrogen transport in a tundra landscape: the effects of early and late growing season lateral N inputs on arctic soil and plant N pools and N2O fluxes

Understanding N budgets of tundra ecosystems is crucial for projecting future changes in plant community composition, greenhouse gas balances and soil N stocks. Winter warming can lead to higher tundra winter nitrogen (N) mineralization rates, while summer warming may increase both growing season N mineralization and plant N demand. The undulating tundra landscape is inter-connected through water and solute movement on top of and within near-surface soil, but the importance of lateral N fluxes for tundra N budgets is not well known. We studied the size of lateral N fluxes and the fate of lateral N input in the snowmelt period with a shallow thaw layer, and in the late growing season with a deeper thaw layer. We used 15N to trace inorganic lateral N movement in a Low-arctic mesic tundra heath slope in West Greenland and to quantify the fate of N in the receiving area. We found that half of the early-season lateral N input was retained by the receiving ecosystem, whereas half was transported downslope. Plants appear as poor utilizers of early-season N, indicating that higher winter N mineralization may influence plant growth and carbon (C) sequestration less than expected. Still, evergreen plants were better at utilizing early-season N, highlighting how changes in N availability may impact plant community composition. In contrast, later growing season lateral N input was deeper and offered an advantage to deeper-rooted deciduous plants. The measurements suggest that N input driven by future warming at the study site will have no significant impact on the overall N2O emissions. Our work underlines how tundra ecosystem N allocation, C budgets and plant community composition vary in their response to lateral N inputs, which may help us understand future responses in a warmer Arctic.

Spatially Resolved Proteomic Analysis of the Lens Extracellular Diffusion Barrier.

PurposeThe presence of a physical barrier to molecular diffusion through lenticular extracellular space has been repeatedly detected. This extracellular diffusion barrier has been proposed to restrict the movement of solutes into the lens and to direct nutrients into the lens core via the sutures at both poles. The purpose of this study is to characterize the molecular components that could contribute to the formation of this barrier.MethodsThree distinct regions in the bovine lens cortex were captured by laser capture microdissection guided by dye penetration. Proteins were digested by Lys C and trypsin. Mass spectrometry–based proteomic analysis followed by gene ontology and protein interaction network analysis was performed.ResultsDye penetration showed that fiber cells first shrink the extracellular spaces of the broad sides followed by closure of the extracellular space between narrow sides at a normalized lens distance (r/a) of 0.9. Accompanying the closure of extracellular space of the broad sides, dramatic proteomic changes were detected, including upregulation of several cell junctional proteins. AQP0 and its interacting partners, Ezrin and Radixin, were among a few proteins that were upregulated, accompanying the closure of extracellular space of the narrow sides, suggesting a particularly important role for AQP0 in controlling the narrowing of the extracellular spaces between fiber cells. The results also provided important information related to biological processes that occur during fiber cell differentiation such as organelle degradation, cytoskeletal remodeling, and glutathione synthesis.ConclusionsThe formation of a lens extracellular diffusion barrier is accompanied by significant membrane and cytoskeletal protein remodeling.

Assessing the hydraulic reduction performance of HYDRUS-1D for application of alkaline irrigation in variably-saturated soils: Validation of pH driven hydraulic reduction scaling factors

Land application of alkaline irrigation water is an increasing practice in most agricultural lands around the world due to the shortage of freshwater resources. Accurate evaluation of the effects of alkalinity on soil properties is essential to avoid environmental risks. In this study, we used long leaching columns to evaluate alkalinisation and sodification hazards in soils in the laboratory at different water qualities (0, 100, 310 and 650 HCO3-, mg L−1) with electrical conductivity (EC) ≈ 2.1 dS m−1 and sodium adsorption ratio (SAR) ≈ 12 (mmolc L−1)0.5. The ability of the HYDRUS-1D model to simulate solute and water movement under unsaturated conditions in columns of 40 cm height filled with acidic, neutral or alkaline soils was also assessed. Changes in soil EC, SAR, pH and alkalinity were monitored at 5, 15, 25 and 35 cm depths for 290 days. Increased solution alkalinity resulted in increased pH, alkalinity and sodicity within the soil profile, in particular for the soil surface and acidic soils. In general, the HYDRUS model, using the standard hydraulic reduction scaling factor, was able to simulate the effects of alkalinity in the soil profile and the associated hydraulic conductivity reduction. Amending the pH driven hydraulic reduction scaling factor in the model to a non-linear, soil-specific, pedotransfer function significantly improved the correlation between predicted and observed hydraulic conductivity. The findings of this study provide validation for a non-linear approach towards determining the pH hydraulic reduction scaling factor in the HYDRUS-1D model for unsaturated conditions. However, it is noted that further improvement of this non-linear approach is required to incorporate other factors governing soil structural stability.

Watching plants’ dance: movements of live and dead branches linked to atmospheric water demand

AbstractDiurnal branch movements in woody plants have only recently been described in detail. While previously only vegetative and reproductive structures have been known to move on hourly timescales, imaging technologies such as terrestrial laser scanning and near‐surface repeat digital photography provide a means of remotely monitoring plant movements at high enough temporal and spatial resolution to capture rhythmic movements of woody material. Virtually, nothing is known about the range of species and ecosystems in which woody movements might occur or what causes these movements. We report that diurnal woody branch movements occur in a number of tree and shrub species across a broad range of abiotic conditions. We examined detailed branch movements in one species, creosote (Larrea tridentata), and found that branch movements were highly correlated with humidity, air temperature, vapor pressure deficit, and stem water potential: all factors related to plant water status. We also found that live and dead branch movements were distinct in the timing of their movements and in the abiotic conditions with which they were most correlated. Changes in dead branch position were most correlated with humidity, with these movements consistently lagging 1–2 h behind changes in humidity. Live branch movements were also highly correlated with vapor pressure deficit and humidity but went from lagging 1–2 h behind changes in these abiotic conditions in summer to being nearly in sync in winter. We believe that this is the first study that (1) documents diurnal branch movements in creosote, (2) differentiates between the movements of live and dead branches, and (3) relates environmental data to these movements. We hope these findings encourage other researchers to more closely examine imagery from their sites for evidence of branch movements, which may provide deeper insights into water and solute movements in plants and physiological responses to water stress.

Natural Transform along with HPM Technique for Solving Fractional ADE

The authors of this paper solve the fractional space-time advection-dispersion equation (ADE). In the advection-dispersion process, the solute movement being nonlocal in nature and the velocity of fluid flow being nonuniform, it leads to form a heterogeneous system which approaches to model the same by means of a fractional ADE which generalizes the classical ADE, where the time derivative is substituted through the Caputo fractional derivative. For the study of such fractional models, various numerical techniques are used by the researchers but the nonlocality of the fractional derivative causes high computational expenses and complex calculations so the challenge is to use an efficient method which involves less computation and high accuracy in solving such models numerically. Here, in order to get the FADE solved in the form of convergent infinite series, a novel method NHPM (natural homotopy perturbation method) is applied which couples Natural transform along with the homotopy perturbation method. The homotopy peturbation method has been applied in mathematical physics to solve many initial value problems expressed in the form of PDEs. Also, the HPM has an advantage over the other methods that it does not require any discretization of the domains, is independent of any physical parameters, and only uses an embedding parameter p ∈ 0 , 1 . The HPM combined with the Natural transform leads to rapidly convergent series solutions with less computation. The efficacy of the used method is shown by working out some examples for time-fractional ADE with various initial conditions using the NHPM. The Mittag-Leffler function is used to solve the fractional space-time advection-dispersion problem, and the impact of changing the fractional parameter α on the solute concentration is shown for all the cases.

Preferential solute transport under variably saturated conditions in a silty loam soil: Is the shallow water table a driving factor?

A shallow water table might enhance preferential solute movement by modifying both the water flow and solute dynamics. In this study, we estimated soil hydraulic and solute transport parameters through a tracer experiment in lysimeters comparing different water table levels. In a set-up of 12 lysimeters, the bottom boundary condition was set as a water table depth of 120 cm, or 60 cm, or as free drainage. A tracer solution of bromide (250 mg l−1, 40 mm) was added to each lysimeter and soil water was sampled with suction cups at different depths for the following 174 days. Soil water content and matric potential were monitored using TDR probes and electronic tensiometers at the same depths. Soil hydraulic and solute transport parameters in different soil layers were estimated by inverse modeling using HYDRUS 1D. Soil hydraulic parameters were estimated from the Mualem-van Genuchten equations, while both the advection–dispersion (ADE) and physical non-equilibrium mobile-immobile water (MIM) models were used to describe the solute transport. Moreover, the soil pore network was analyzed by means of 3D X-ray microtomography. Results showed different solute dynamics between contrasting water table managements. With free drainage, solute in the immobile domain was negligible, and its transport was fully associated with the mobile water flow. In contrast, a shallow water table affected the tracer transport, by modifying a) the soil pore network, with an increase of the macropores and a reduction of the pore connectivity; b) the flow field, with an increase of immobile water and a reduction of αMIM, indicating slow exchange between mobile and immobile regions, in turn promoting preferential pathways. Hence, groundwater pollution might be worsened by preferential solute transport of agrochemicals occurring with shallow water table conditions.

The Epithelial Cell Leak Pathway.

The epithelial cell tight junction structure is the site of the transepithelial movement of solutes and water between epithelial cells (paracellular permeability). Paracellular permeability can be divided into two distinct pathways, the Pore Pathway mediating the movement of small ions and solutes and the Leak Pathway mediating the movement of large solutes. Claudin proteins form the basic paracellular permeability barrier and mediate the movement of small ions and solutes via the Pore Pathway. The Leak Pathway remains less understood. Several proteins have been implicated in mediating the Leak Pathway, including occludin, ZO proteins, tricellulin, and actin filaments, but the proteins comprising the Leak Pathway remain unresolved. Many aspects of the Leak Pathway, such as its molecular mechanism, its properties, and its regulation, remain controversial. In this review, we provide a historical background to the evolution of the Leak Pathway concept from the initial examinations of paracellular permeability. We then discuss current information about the properties of the Leak Pathway and present current theories for the Leak Pathway. Finally, we discuss some recent research suggesting a possible molecular basis for the Leak Pathway.

Monitoring nitrogen leaching under different fertiliser applications during the early growth stage of sugarcane using GS3 sensors: a case study on Negros Island, Philippines

ABSTRACT Nitrogen (N) is normally applied twice during sugarcane cultivation on Negros Island in the Philippines. As the first application is carried out during the early growth stage, there is a high possibility that N is not absorbed sufficiently by the sugarcane and a large amount of N may be leached with percolating water. To investigate this leaching, we monitored the vertical movement of soil water and soil solutes using GS3 dielectric moisture and electrical conductivity (EC) sensors in a sugarcane field on Negros Island. The monitoring was conducted after the first N application at different application rates (50% or 100% of the recommended rate) and timings (immediately or 30 days after planting [DAP]). The EC values increased when 100%-N was applied immediately after planting, indicating that N leached into the deeper soil layer. The monitoring results suggest that the applied N did not remain in the root zone (due to leaching) and was not replenished until the second application, when the absorption ability of the sugarcane was high. Conversely, when 100%-N was applied at 30 DAP, the applied N remained in the root zone until the second application. When 50%-N was applied at 30 DAP, the increase in EC was small compared to the 100%-N application. These results indicate that applying N immediately after planting at the recommended rate led to an insufficient nutrient supply for the sugarcane, as well as the loss of N fertiliser via leaching.

A genome-wide association study suggests correlations of common genetic variants with peritoneal solute transfer rates in patients with kidney failure receiving peritoneal dialysis

Movement of solutes across the peritoneum allows for the use of peritoneal dialysis to treat kidney failure. However, there is a large inter-individual variability in the peritoneal solute transfer rate (PSTR). Here, we tested the hypothesis that common genetic variants are associated with variability in PSTR. Of the 3561 participants from 69 centers in six countries, 2850 with complete data were included in a genome-wide association study. PSTR was defined as the four-hour dialysate/plasma creatinine ratio from the first peritoneal equilibration test after starting PD. Heritability of PSTR was estimated using genomic-restricted maximum-likelihood analysis, and the association of PSTR with a genome-wide polygenic risk score was also tested. The mean four-hour dialysate/plasma creatinine ratio in participants was 0.70. In 2212 participants of European ancestry, no signal reached genome-wide significance but 23 single nucleotide variants at four loci demonstrated suggestive associations with PSTR. Meta-analysis of ancestry-stratified regressions in 2850 participants revealed five single-nucleotide variants at four loci with suggestive correlations with PSTR. Association across ancestry strata was consistent for rs28644184 at the KDM2B locus. The estimated heritability of PSTR was 19%, and a permuted model polygenic risk score was significantly associated with PSTR. Thus, this genome-wide association study of patients receiving peritoneal dialysis bolsters evidence for a genetic contribution to inter-individual variability in PSTR.

Effects of ice cover on soil water, heat, and solute movement: An experimental study

In cold regions, the surface cover plays a pivotal role in understanding the soil water and energy balance during winter. Although the effects of other types of surface cover on soil freezing-thawing process have been studied for decades, the effects of ice cover derived from irrigation remain unclear. To estimate the effects of ice cover on soil water, heat, and solute movement, ice coverage and field observation data were collected for three winter periods from 2013 to 2016 in Inner Mongolia, China. The collected data was then analyzed using the principal component analysis (PCA) method. The dynamics of the water, heat, and solute transport were also investigated using in-situ plot experiments conducted in four lysimeters, which were controlled by manipulating the thickness of the ice cover. The thickness of the ice cover was controlled by the amount of water irrigation in the treatment plots, and no irrigation was performed in the control plot. The results of the field-scale survey and PCA indicated that the ice cover had positive effect on soil salinization control and moisture preservation after autumn irrigation (AI). An unique air space created during the ice formation might enhance the heat insulation effect of ice cover. Furthermore, the results of the in-situ plot experiment revealed that the freezing of the irrigated soil could be divided into the unstable freezing period (UFP) and stable freezing period (SFP) when considering the ice cover. During the UFP, the upward movement of the solute that was leached by the irrigation water was reduced as the development of the freezing front was hindered by the irrigation water. During the SFP, the penetration of the freezing front was further reduced by the combination of the ‘inherited’ thermal regime from the UFP and the input solar energy reduced by the remaining ice cover and air space, which decreased the water and solute transport. The study findings aid in achieving an improved understanding of ice cover on agricultural fields in cold regions, and have important implications for water conservation and salinization control.

Apoplastic lipid barriers regulated by conserved homeobox transcription factors extend seed longevity in multiple plant species.

Cutin and suberin are lipid polyesters deposited in specific apoplastic compartments. Their fundamental roles in plant biology include controlling the movement of gases, water and solutes, and conferring pathogen resistance. Both cutin and suberin have been shown to be present in the Arabidopsis seed coat where they regulate seed dormancy and longevity. In this study, we use accelerated and natural ageing seed assays,glutathione redox potential measures,optical and transmission electron microscopy and gas chromatography-mass spectrometry to demonstrate that increasing the accumulation of lipid polyesters in the seed coat is the mechanism by which the AtHB25 transcription factor regulates seed permeability and longevity. Chromatin immunoprecipitation during seed maturation revealed that the lipid polyester biosynthetic gene long-chain acyl-CoA synthetase2 (LACS2)is a direct AtHB25 binding target. Gene transfer of this transcription factor to wheat and tomato demonstrated the importance of apoplastic lipid polyesters for the maintenance of seed viability. Our work establishes AtHB25 as a trans-species regulator of seed longevity and has identified the deposition of apoplastic lipid barriers as a key parameter to improve seed longevity in multiple plant species.

A Review of Mathematics Determining Solute Uptake at the Blood-Brain Barrier in Normal and Pathological Conditions.

The blood–brain barrier (BBB) limits movement of solutes from the lumen of the brain microvascular capillary system into the parenchyma. The unidirectional transfer constant, Kin, is the rate at which transport across the BBB occurs for individual molecules. Single and multiple uptake experiments are available for the determination of Kin for new drug candidates using both intravenous and in situ protocols. Additionally, the single uptake method can be used to determine Kin in heterogeneous pathophysiological conditions such as stroke, brain cancers, and Alzheimer’s disease. In this review, we briefly cover the anatomy and physiology of the BBB, discuss the impact of efflux transporters on solute uptake, and provide an overview of the single-timepoint method for determination of Kin values. Lastly, we compare preclinical Kin experimental results with human parallels.