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An acto-myosin contractile ring, which forms after anaphase onset and is highly regulated in time and space, mediates cytokinesis, the final step of mitosis. The chromosomal passenger complex (CPC), composed of Aurora-B kinase, INCENP, borealin and survivin (also known as BIRC5), regulates various processes during mitosis, including cytokinesis. It is not understood, however, how CPC regulates cytokinesis. We show that survivin binds to non-muscle myosin II (NMII), regulating its filament assembly. Survivin and NMII interact mainly in telophase, and Cdk1 regulates their interaction in a mitotic-phase-specific manner, revealing the mechanism for the specific timing of survivin–NMII interaction during mitosis. The survivin–NMII interaction is indispensable for cytokinesis, and its disruption leads to multiple mitotic defects. We further show that only the survivin homodimer binds to NMII, attesting to the biological importance for survivin homodimerization. We suggest a novel function for survivin in regulating the spatio-temporal formation of the acto-NMII contractile ring during cytokinesis and we elucidate the role of Cdk1 in regulating this process. This article has an associated First Person interview with the first author of the paper.

Spatial heterogeneity in the chemical concentration of interstitial water in the vadose zone was previously observed under apparently homogeneous surface conditions on two leveled fields sprinkler irrigated with treated sewage effluents on the phreatic Coastal Plain aquifer of Israel. This phenomenon greatly hampers the monitoring of groundwater quality. In this study we report on the presence of puddles of different size and shape that were sporadically observed in these fields. Temporal variability noted in the concentration of treated sewage effluents components in the puddles were considered to be related to evapotranspiration and degradation. For example: increases in the electrical conductivity (up to 1.32 mS/cm), and in the concentrations of chloride (up to 521 mg/L), dissolved organic carbon (up to 28.4 mg/L), and carbamazepine (up to 780 ng/L) and decreases in the concentrations of nitrate (up to 20.1 mg/L) and caffeine (3396 ng/L). Variable trends in concentration were observed for sulfamethoxazole, venlafaxine, 10-hydroxy-10,11-dihydrocarbamazepine and o-desmethylvenlafaxine. The presence of puddles was not necessarily related to areas with high irrigation water input. It is postulated that the continuous chemical variability in the puddles, whose location and size are also variable, determine a heterogeneous influx of solutes into the soil and subsequently into the vadose zone.

SummaryParental imprinting results in monoallelic parent-of-origin-dependent gene expression. However, many imprinted genes identified by differential methylation do not exhibit complete monoallelic expression. Previous studies demonstrated complex tissue-dependent expression patterns for some imprinted genes. Still, the complete magnitude of this phenomenon remains largely unknown. By differentiating human parthenogenetic induced pluripotent stem cells into different cell types and combining DNA methylation with a 5′ RNA sequencing methodology, we were able to identify tissue- and isoform-dependent imprinted genes in a genome-wide manner. We demonstrate that nearly half of all imprinted genes express both biallelic and monoallelic isoforms that are controlled by tissue-specific alternative promoters. This study provides a global analysis of tissue-specific imprinting in humans and suggests that alternative promoters are central in the regulation of imprinted genes.

Maturity onset diabetes of the young (MODY) is a hereditary form of diabetes mellitus presenting at childhood or adolescence, which eventually leads to pancreatic β-cells dysfunction. The underlying genetic basis of MODY disorders is haploinsufficiency, where loss-of-function mutations in a single allele cause the diabetic phenotype in heterozygous patients. MODY1 is a type of MODY disorder resulting from a mutation in the transcription factor hepatocyte nuclear factor 4 alpha (HNF4α). In order to establish a human based model to study MODY1, we generated patient-derived induced pluripotent stem cells (iPSCs). Differentiation of these pluripotent cells towards the pancreatic lineage enabled to evaluate the effects of the MODY1 mutation and its impact on endodermal and pancreatic cells. Analyzing the gene expression profiles of differentiated MODY1 cells, revealed the outcome of HNF4α haploinsufficiency on its targets. This molecular analysis suggests that the differential expression of HNF4α target genes in MODY1 is affected by the number of HNF4α binding sites, their distance from the transcription start site, and the number of other transcription factor binding sites. These features may help explain the molecular manifestations of haploinsufficiency in MODY1 disease. Keywords: MODY1, HNF4α, iPS cells, Differentiation, Transcription factor, Binding sites

Field-scale transport of conservative and reactive solutes through a deep vadose zone was analyzed by means of two different model processes for the local description of the transport. The first is the advection-dispersion equation (ADE) model, and the second is the mobile-immobile (MIM) model. The analyses were performed by means of three-dimensional (3-D), numerical simulations of flow and transport considering realistic features of the flow system, pertinent to a turf field irrigated with treated sewage effluents (TSE). Simulated water content and concentration profiles were compared with available measurements of their counterparts. Results of the analyses suggest that the behavior of both solutes in the deep vadose zone of the Glil Yam site is better quantified by the MIM model than by the ADE model. Reconstruction of the shape of the measured solute concentration profiles using the MIM model required relatively small mass transfer coefficient, γ, and relatively large volume fraction of the immobile water θim. This implies that for an initially nonzero solute concentration profile, as compared with the MIM model, the ADE model may significantly overestimate the rate at which solutes are loaded in the groundwater. On the contrary, for an initially zero solute concentration profile, as compared with the MIM model, the ADE model may significantly underestimate solute velocities and early arrival times to the water table. These findings stem from the combination of relatively small γ and relatively large θim taken into account in the MIM model. In the first case, this combination forces a considerable portion of the solute mass to reside in the immobile region of the water-filled pore space, while the opposite is true in the second case.

The studied 25 by 30 km site of Porto Alegre Southern Brazil fractured granites, accounts for surface lineaments assumed to mimic its fractures. Observations address the lineaments spatial characteristics, significant deviations between stationary groundwater levels condensed at part of the domain while sparse at most of the area, and no pumping/injection rates. Fractured media feature, e.g., dead end pathways, lack of flow interconnections, and preferential infiltration paths. These characteristics are not in line with the implementation of continuum-based macroscopic balance equations. Subject to such data and the inherent features, the objective was to verify if with lumped parameter modeling (LPM) following a flow directed graph approach we can assess a groundwater flow pattern. We at first addressed the site lineaments layout for which the evaluation of the hydraulic heads revealed the existence of isolated lineament clusters, leading to flow or no-flow zones. Aiming at better spatial distribution of flow distributions and based on the site surface lineaments, we established a virtual fracture network (VFN) for which the domain was subdivided into representative elementary area (REA) cells. Each REA was chosen so that the ratio of all its lineament lengths over that of the cell area remained practically unchanged between two consecutive subdivisions. Within each REA, lineaments with similar geometrical characteristics were considered as segment groups. The VFN was established upon elongating segments that created intersection points with other stretched segments from cells at the circumference of a considered REA. The evaluated steady state hydraulic head was compared between two LPM solutions: (1) Referring to flow along the VFN branches between intersection points, and (2) Using a flux interconnected network (FIN) for which each REA was replaced by a pole communicating flow to other poles. Computation of the FIN approach was significantly less intense. Both of these approaches resolved with hydraulic head isolines consistently similar to those obtained by interpolation between the observed groundwater levels. One reported event of a Nitrate polluted well and its plausible contaminating source within the study domain, show that it is in line with the predicted resultant flow direction following the FIN map.

The genetic stability of induced pluripotent stem (iPS) cells has a significant impact on their potential use in regenerative medicine and basic research. Analysis of the genomic integrity of iPS cells suggests a tendency to develop aberrations ranging from whole chromosome trisomies to single nucleotide mutations. Furthermore, fluctuations in telomere elongation and changes in mitochondrial DNA are also observed. Some mutations may already exist in the founder cells or result from prolonged culturing, however, many of the mutations occur during the reprogramming event. Thus, great care should be given to the initial characterization and subsequent culturing of new iPS cell lines in order to avoid the use of potentially aberrant cells.

Two sequential multilevel profiles were obtained in an observation well opened to a 130-m thick, unconfined, contaminated aquifer in Tel Aviv, Israel. While the general profile characteristics of major ions, trace elements, and volatile organic compounds were maintained in the two sampling campaigns conducted 295 days apart, the vertical locations of high concentration gradients were shifted between the two profiles. Principal component analysis (PCA) of the chemical variables resulted in a first principal component which was responsible for ∼60% of the variability, and was highly correlated with depth. PCA revealed three distinct depth-dependent water bodies in both multilevel profiles, which were found to have shifted vertically between the sampling events. This shift cut across a clayey bed which separated the top and intermediate water bodies in the first profile, and was located entirely within the intermediate water body in the second profile. Continuous electrical conductivity monitoring in a packed-off section of the observation well revealed an event in which a distinct water body flowed through the monitored section (v ∼ 150 m yr−1). It was concluded that the observed changes in the profiles result from dominantly lateral flow of water bodies in the aquifer rather than vertical flow. The significance of this study is twofold: (a) it demonstrates the utility of sequential multilevel observations from deep wells and the efficacy of PCA for evaluating the data; (b) the fact that distinct water bodies of 10 to 100 m vertical and horizontal dimensions flow under contaminated sites, which has implications for monitoring and remediation.

This issue paper presents how certain policies regarding management of groundwater quality lead to unexpected and undesirable results, despite being backed by seemingly reasonable assumptions. This happened in part because the so-called reasonable decisions were not based on an integrative and quantitative methodology. The policies surveyed here are: (1) implementation of a program for aquifer restoration to pristine conditions followed, after failure, by leaving it to natural attenuation; (2) the “Forget About The Aquifer” (FATA) approach, while ignoring possible damage that contaminated groundwater can inflict on the other environmental systems; (3) groundwater recharge in municipal areas while neglecting the presence of contaminants in the unsaturated zone and conditions exerted by upper impervious surfaces; (4) the Soil Aquifer Treatment (SAT) practice considering aquifers to be “filters of infinite capacity”; and (5) focusing on well contamination vs. aquifer contamination to conveniently defer grappling with the problem of the aquifer as a whole. Possible reasons for the failure of these seemingly rational policies are: (1) the characteristic times of processes associated with groundwater that are usually orders of magnitude greater than the residence times of decision makers in their managerial position; (2) proliferation of improperly trained “groundwater experts” or policymakers with sectoral agendas alongside legitimate differences of opinion among groundwater scientists; (3) the neglect of the cyclic nature of natural phenomena; and (4) ignoring future long-term costs because of immediate costs.

Electrical conductivity (EC) logs were obtained by both open-borehole logging and passive multilevel sampling (MLS) in an observation borehole penetrating the Coastal Aquifer in Tel Aviv, Israel. Homogeneous vertical velocities for a 70-m thick subaquifer were approximated from each profile using a steady-state advection-diffusion model. The open-borehole log led to an overestimation of the steady-state upward advective flux of deep brines (vertical velocity of 0.95 cm/yr as compared to 0.07 cm/yr for the MLS profile). The combination of depth-dependent data and the suggested simple modeling approach comprises a method for assessing the vertical location of salinity sources and the nature of salt transport from them (i.e., advective vs. diffusive). However, in this case, the easily obtained open-borehole logs should not be used for collecting depth-dependent data.

Compound-specific isotope analysis (CSIA) can potentially be used to relate vapor phase contamination by volatile organic compounds (VOCs) to their subsurface sources. This field and modeling study investigated how isotope ratios evolve during migration of gaseous chlorinated ethenes across a 18 m thick unsaturated zone of a sandy coastal plain aquifer. At the site, high concentrations of tetrachloroethene (PCE up to 380 µg/L), trichloroethene (TCE up to 31,600 µg/L), and cis-1,2-dichloroethene (cDCE up to 680 µg/L) were detected in groundwater. Chlorinated ethene concentrations were highest at the water table and steadily decreased upward toward the land surface and downward below the water table. Although isotopologues have different diffusion coefficients, constant carbon and chlorine isotope ratios were observed throughout the unsaturated zone, which corresponded to the isotope ratios measured at the water table. In the saturated zone, TCE became increasingly depleted along a concentration gradient, possibly due to isotope fractionation associated with aqueous phase diffusion. These results indicate that carbon and chlorine isotopes can be used to link vapor phase contamination to their source even if extensive migration of the vapors occurs. However, the numerical model revealed that constant isotope ratios are only expected for systems close to steady state.

This work demonstrates significant vertical variability in the chemical composition of groundwater (Cl − from 150 to 550 mg/L, \({\rm{NO}}_{3}^{-}\) from 3 to 70 mg/L, trichloroethene from 350 to 55,000 μg/L and CrTotal from 3 to 2,900 μg/L) along a 130 m thick vertical section passing through two subaquifers of the Costal Plain aquifer of Israel. Water samples were obtained by multilevel sampler under natural gradient flow conditions from a monitoring well which penetrates the entire aquifer. The vertical chemical variability detected at a single point in time in this well was found to be similar to the range of concentrations detected for Cl − in pumping wells located over an area of about 1,000 km2 in the same aquifer. Similarly, vertical variations in \({\rm{NO}}_{3}^{-}\) concentration in the single monitoring well represent more than 50% of the total variation in nitrate levels in pumping wells sampled across the entire aquifer. These results graphically illustrate that data from pumping wells, which extract unknown mixtures of groundwater from different depths, cannot provide adequate information about groundwater quality for management purposes.

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated–unsaturated interface region (SUIR; depth of ∼18 m) of a sandy phreatic aquifer were measured in two monitoring wells located 25 m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis -1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.

A theory is developed providing a rational framework for spatial scale- dependent fluid’s flow and heat transfer, and mass of a component migrating with it through porous media. Introducing the assumption of a non-Brownian type motion and referring to asymptotic expansion in powers of a small defined parameter, we develop a novel approach associated with macroscopic balance equations obtained by averaging over a Representative Elementary Volume (REV). We prove that these equations can be decomposed into a primary part that refers to the REV length scale and a secondary part valid at a length scale smaller than that of the corresponding REV length. Further to our previous development, we obtain two general forms of the primary and secondary macroscopic balance equations. One is based on the assumption that the advective flux of the extensive quantity is dominant over that of the dispersive flux, whereas the other disregards this assumption. Moreover we also introduce the primary and secondary macroscopic forms for the fluid heat- transfer equation. Considering a Newtonian fluid, the resulting primary Navier–Stokes equation can vary from a nonlinear wave equation to a drag-dominant equation at the fluid–solid interface (Darcy’s law). The secondary momentum balance equation describes a wave equation governing the concurrent propagation of the intensive momentum and the dispersive momentum flux, deviating from their corresponding average terms. The primary macroscopic fluid heat-transfer equation accounts for advective and dispersive heat fluxes and the secondary macroscopic heat-transfer equation involves the simultaneous advection of heat deviating from its corresponding intensive average quantity. The primary macroscopic solute mass balance equation accounts for advection and hydrodynamic dispersion. The secondary macroscopic component mass balance equation is in the form of pure advection governing migration of the deviation from the average component concentration. At this stage, we focus on establishing the viability of the developed theory. We do this by arguing that field observations of motion at small spatial scales are coherent with the hyperbolic characteristics of the secondary balance equations. Field observations under natural gradient flow conditions show excessive high concentration (average of 50 mg/L) of colloids under land irrigated by sewage effluents. We argue that this displacement of condensed colloidal parcels manifests the theoretical findings for the smaller spatial scale. Further evidence show the accumulation of particles moving behind the front of an emitted shockwave. We consider this as an experimental proof reinforcing the argument that colloidal migration is subject to the action of a shockwave in the fluid and pure advection transport, governed by the respective suggested hyperbolic macroscopic balance equations of fluid momentum and component mass at the smaller spatial scale.

The Tel Aviv metropolitan region (200 km2), located on the sandy and phreatic Mediterranean Coastal Plain aquifer in Israel, is an example of a contaminated megasite that is additionally complicated by being part of a densely populated urban environment. Despite being a major source of fresh potable water, no dedicated aquifer monitoring systems exist. The vast majority of tested water supply wells (82% of 90 wells) were found to be contaminated with one or more chlorinated volatile organic compounds (Cl-VOCs) such as trichloroethene and tetrachloroethene, originating from multiple sources, including former industrial sites. Temporal variations in Cl-VOC concentrations in water supply wells were large and unpredictable. Such aquifer contamination requires immediate action in terms of aquifer management and municipal water distribution. To cope with temporal and spatial variations in contaminant concentrations in water supply wells in an area where monitoring wells are absent, aquifer impact areas were defined based on the concentration of the Cl-VOC contaminant in pumping wells that was greatest in relation to its drinking water standard over a 3-year period. Such a map can be used to define water supply treatment and municipal well monitoring requirements, until an adequate monitoring system is established.

Three volatile organic compound (VOC) field profiles were obtained during a period of 13 mo with a passive multilayer sampler (MLS) from a monitoring well located in the VOC-contaminated sandy phreatic Coastal Plain aquifer of Israel in the Tel Aviv area. The profiles presented here are unique in that they span both the saturated and unsaturated zones, through the saturated-unsaturated interface region (SUIR), and represent VOC concentrations from a single borehole. In groundwater just below the water table, the major contaminant, trichloroethylene (TCE), was present in concentrations up to 260000 micrograms/L water, and in the unsaturated zone just above the water table, in concentrations up to 124000 micrograms/L air. Other contaminants detected in high concentrations (as high as several thousands of micrograms/L) included tetrachloroethylene (PCE), cis-1,2-dichloroethylene (cis-1,2-DCE) and 1,1-dichloroethylene (1,1-DCE). In the three profiles, TCE and PCE concentrations were greatest at the water table and decreased with increasing distance from the water table both into the saturated and unsaturated zones. Temporal variations in maximal TCE vapor concentrations ranging from 44000 to 124000 micrograms/L air were also observed between profiles. The passive diffusion sampling characteristic of the MLS makes it possible to obtain unmixed vertical samples such that, for example, differences as great as 24000 micrograms TCE/L air can be measured in consecutive samples located only 12 cm apart in the unsaturated zone. The vertical detail is unique compared with other field sampling methods. Vertical detail is of utmost importance in interface regions, such as the SUIR, where water content in both the unsaturated and saturated zones varies significantly with depth, time, and space.

The purpose of this study was to test in the laboratory the performance of a passive multilayer sampler (MLS) for obtaining detailed profiles of gas-phase volatile organic compounds (VOCs) in unsaturated sediments. The MLS is essentially a chain of isolated, cylindrical stainless steel dialysis cells filled with distilled water and closed with membranes at both ends. The sampling principle is based on passive equilibration of the unsaturated zone gas phase with water in the cells. Using trichloroethene (TCE) as a model VOC, and after testing the required equilibration time in the laboratory (about 50 h), results of a large container (210 L) experiment show that TCE concentrations obtained by the MLS deployed inside a well screen corresponded very well to the profile obtained by dialysis cells buried in the sediment. A field profile taken at the saturated-unsaturated interface region of a VOC-contaminated area using the MLS shows steep TCE concentration gradients (1119 microg TCE/L-air/cm) in the gas phase of the unsaturated zone just above the water table.

Research on market categories suggests that category non-conformity may reduce consumers’ willingness to purchase. But research also suggests that producers may take advantage of the taken-for-gran...

Saline groundwaters from the Israeli coastal aquifer were analyzed for their radiocarbon and tritium content to assess the rate of seawater penetration. The low 14C values (28–88 pMC versus 100–117 pMC in seawater) imply an apparent non-recent seawater source, or water-rock interactions along the penetration route. The latter process is supported by measurable tritium values at some locations, which imply a relatively rapid rate of seawater intrusion. In other locations, low tritium values (13C values in saline groundwater (average of −5.3‰ versus 0‰ in seawater) indicate that the dissolved carbon pool is comprised of a significant fraction of organic carbon. A linear negative correlation between δ13C and 14C implies that this organic source is old (low 14C values).

The surface topography of a natural fracture intersecting a chalk formation was mapped using a high-resolution laser-scanning device, and its roughness was evaluated using five different criteria. Two coated and two uncoated slices of the natural fracture surface were encased in flow cells and exposed to short (24 and 8 hours) interactions with percolating synthetic rainwater and industrial wastewater, followed by long drying periods (weeks). These flow experiments simulated the intermittent infiltration of surface runoff and industrial effluents typical of the study area and resulted in erosion of the fracture surfaces and modification of their roughness. The temporal variations in surface roughness were evaluated using three commonly used criteria (standard deviation from mean heights, differences between maximum and minimum heights, and the root-mean-square roughness) and two newly developed measures, namely, the slopes on the surfaces and a calculated roughness-related ratio (RRR). The mean slope maps and RRR calculations were found to be good criteria for evaluating surface topography and its uniformity across the fracture surface. The coated surfaces were significantly rougher, had greater relief, more heterogeneous topography, and a larger surface area than the uncoated surfaces. The results suggest that coating and fast weathering (caused by intermittent flow events) significantly change roughness, surface area, relief, and the heterogeneity of a fracture surface. These, in turn, may affect the spatial distribution of flow paths across that fracture surface. Consequently, when exploring the properties of fracture surfaces and fracture flow, the impact of surface skin and variations of the surface properties over short timescales should be taken into account.

Field measurements of profiles of the water content of a 7-m deep, sandy, phreatic aquifer have been conducted at the same site before and after the rainy season. The field site is an uncultivated region located in a citrus orchard, north of the city of Netanya, on the Coastal Plain aquifer of Israel. In two single-day campaigns, 13 boreholes were drilled in relatively homogeneous sandy sediments in an area subjected to infiltration of rain only. Twelve of the thirteen boreholes were located within a radius of 5 m. Water content, as a function of depth, was obtained from continuous cores. We found that the distribution of water within the capillary fringe (CF) was compact — denoting that there was an abrupt change in water content with increasing height above the water table. The height of the CF was about 1.4 m at each point above the water table, and over a horizontal distance of about 4 m, this height varied by up to 33% and 50% before and after the rainy season, respectively. Saturated conditions were detected in some regions of the CF and unsaturated conditions were found up to 1.5 m below the water table. The distribution of water in the capillary fringe remained compact while being displaced vertically as the water table rose 35 cm after the winter rains. These observations are consistent with pore level models of the water distribution within the capillary fringe in a porous media.

The topographical variations in a fractured chalk surface were studied by laser scanning in laboratory experiments after cycles of immersion in tap water and air drying. The surfaces were found to erode by up to 0.295 and 0.352 mm following wetting for 10 min and 14 hours, respectively. Topographical changes were related to the nonuniform release of particles from the surface under no-shear flow conditions. The total amount of particles released decreased exponentially with time during a 96-hour experiment, from 11 mg/L following a wetting period of 10 min (at the beginning of the experiment) to 1 mg/L following a wetting period of 48 hours (at the end of the experiment). These preliminary results suggest that under conditions of variable water content (highly significant in arid and semiarid regions), the aperture, roughness, and flow channels of fractures in soft rocks are transient properties. In the field site, fracture apertures are >1 order of magnitude smaller than expected from the laboratory observations. This discrepancy is related among other possible reasons, to partial wetting and drying cycles and to the development of flow channels within the filling materials rather than along the fracture surfaces.

CO2 profiles obtained along a 30-m-thick unsaturated zone under land irrigated with sewage effluents show two production regions: a seasonal one in the root zone and another, at steady state, near the water table (29 m). On an annual basis the CO2 flux from the deep source toward the atmosphere (6.3 g C m−2 yr−1) is balanced by a similar influx of soluble organic carbon (SOC) from sewage effluents. The δ13C values of soil CO2 indicate that CO2 is produced from plant material in the root zone and from biodegradation of total sedimentary organic carbon in the capillary fringe. High CO2 concentration in the capillary fringe (up to 2%) is likely to reflect a decrease in diffusivity relative to the unsaturated zone due to increase in both water content and tortuosity induced by the capillary fringe structure. The long residence time of SOC and CO2 in the unsaturated zone (29 years at the study site) suggests that the unsaturated zone of deep aquifers may have a significant storage capacity for carbon and may act as a temporary carbon sink.

The extent to which aquifer microbiota can be studied under laboratory or simulated conditions is limited by our inability to authentically duplicate natural conditions in the laboratory. Therefore, extrapolation of laboratory results to real aquifer situations is often criticized, unless validation of the data is performed in situ. Reliable data acquisition is critical for the estimation of chemical and biological reaction rates of biodegradation processes in groundwater and as input data for mathematical models. Typically, in situ geobiochemical studies relied on the injection of groundwater spiked with compounds or bacteria of interest into the aquifer, followed by monitoring the changes over time and space. In situ microcosms provide a more confined study site for measurements of microbial reactions, yet closer to natural conditions than laboratory microcosms. Two basic types of in situ aquifer microcosm have been described in recent years, and both originated from in situ instruments initially designed for geochemical measurements. Gillham et al. [Ground Water 28 (1990) 858–862] constructed an instrument that isolates a portion of an aquifer for in situ biochemical rate measurements. More recently Shati et al. [Environ. Sci. Technol. 30 (1996) 2646–2653] modified a multilayer sampler for studying the activity of inoculated bacteria in a contaminated aquifer. Keeping in mind recent advances in environmental microbiology methodologies such as immunofluorescence direct counts, oligonucleotide and PCR probes, fatty acid methyl esther analysis for the detection and characterization of bacterial communities, measurement of mRNA and expression of proteins, it is evident that much new information can now be gained from in situ work. Using in situ microcosms to study bioremediation efficiencies, the fate of introduced microorganisms and general geobiochemical aquifer processes can shed more realistic light on the microbial underworld. The aim of this paper is to emphasize the importance of in situ studies and to describe two different concepts of construction and application of in situ microcosms for studying microbial activity in aquifers. The overall goal is to promote the development and utilization of these valuable and largely unexplored tools.

The water distribution in the capillary fringe (CF) reflects the interaction of a strongly wetting fluid in a heterogeneous porous medium. Field profiles of gravimetric water content of the CF for a 30m deep, sandy, phreatic aquifer in Israel are critically analyzed in the context of the possible wetting and drainage processes in these sediments. A highly plausible explanation of the profiles is based on the spatial configuration of the CF surface determined from a model of the movement of water within the porous medium. The structural types of CF that can arise from a number of competing pore-scale displacement mechanisms, in the presence of gravity, are characterized by the model. We differentiate between two generic types of CF structures: a tenuous invasion-percolation type and a compact type. Flow, in response to a horizontal pressure gradient, associated with each structure is analyzed. Our interpretation of the field data supports the compact structure with a spatial variation in the height of the CF surface, above the water table, on the order of 1m. In this compact structure horizontal flow is characterized by stagnant regions in the CF above a critical height h c and flow only for regions below h c . The field water content (at h c ) may be used to predict the onset of lateral water flow in the CF.

The motor protein nonmuscle myosin II (NMII) must undergo dynamic oligomerization into filaments to perform its cellular functions. A small nonhelical region at the tail of the long coiled-coil region (tailpiece) is a common feature of all dynamically assembling myosin II proteins. This tailpiece is a key regulatory domain affecting NMII filament assembly properties and is subject to phosphorylation in vivo. We previously demonstrated that the positively charged region of the tailpiece binds to assembly-incompetent NMII-C fragments, inducing filament assembly. In the current study, we investigated the molecular mechanisms by which the tailpiece regulates NMII-C self-assembly. Using alanine scan, we found that specific positive and aromatic residues within the positively charged region of the tailpiece are important for inducing NMII-C filament assembly and for filament elongation. Combining peptide arrays with deletion studies allowed us to identify the tailpiece binding sites in the coiled-coil rod. Elucidation of the mechanism by which the tailpiece induces filament assembly permitted us further investigation into the role of tailpiece phosphorylation. Sedimentation and CD spectroscopy identified that phosphorylation of Thr(1957) or Thr(1960) inhibited the ability of the tailpiece to bind the coiled-coil rod and to induce NMII-C filament formation. This study provides molecular insight into the role of specific residues within the NMII-C tailpiece that are responsible for shifting the oligomeric equilibrium of NMII-C toward filament assembly and determining its morphology.

We present a methodology for the analysis of chemical profiles from the unsaturated zone where ions from the sediment are extracted by two methods:centrifugation and water addition. The methodology enables one to (1) assess the ion amounts present in two different phases, pore water and minerals; (2) determine the depth in the unsaturated profile where the degree of saturation of each mineral is reached; (3) establish the principal direction of water flow; and (4) differentiate between upward transport of water either as vapor or as a saline solution. The methodology was applied to the unsaturated zone of the Dead Sea coastal area where the original salinity of interstitial water in these sediments was >300 g/L. Our analysis of the field data suggests that reduction of interstitial water salinity is the result of vertical upward transport of fresh water from a confined aquifer at a depth of 7 m. Flushing, up to the potentiometric surface (depth of 3.5 m), is due to the positive pressure head of the aquifer. Above the potentiometric surface, upward water transport is due to capillary forces, and flow is maintained by evaporation at the soil surface. Evaporation leads to an increase in the salinity of the rising interstitial solution and to the sequential deposition of salts such as NaCl and KMgCl3 · 6H2O.

This paper describes a new method for the passive sampling of groundwater colloids using a multilayer sampler (MLS). It is based on the use of dialysis cells with large pore size (10 μm) membranes that are in dynamic equilibrium with the mobile colloid and liquid phases in the aquifer. Under laboratory conditions, the dialysis cells reached equilibrium with a suspension of latex microspheres (5 mg/L) after 44−100 h and with a suspension of kaolinite (16−41 NTU; 20−50 mg/L) after 50−180 h. No fractionation was detected in the particle-size distribution between the kaolinite suspensions inside and outside the dialysis cells. Field profiles, obtained under natural gradient flow conditions in a sand and sandstone aquifer, showed large variability (up to 1 order of magnitude) in the colloid content within profiles (e.g., variation of 7 NTU (∼45 mg/L) between cells located at a vertical distance of 40 cm) and between them. The predominant colloidal particles found in the cells were aluminosilicates, CaCO3, sili...

A new method for the in situ study of bacterial activity in aquifers at microscale environments (scale order of centimeters) is presented. It is based on the use of a multilayer sampler (MLS) equip...

Cu and Cd content of standard reference materials (SRMs), minerals (quartz, calcite, kaolinite, and bentonite), and samples of aquifer colloids, obtained under natural gradient flow conditions, were analyzed by solid sampling graphite furnace atomic absorption spectrometry (GFAAS). Pyrolytically coated tubes, designed for the analysis of liquid samples, were successfully used. Recovery of analytes by solid sampling was 106−112% of the certified values of SRMs. Cu concentration in clay minerals, obtained by solid sampling, was about 9-fold (in kaolinite) and 3-fold (in bentonite) higher than that obtained by nitric acid extraction, indicating that Cu is partially incorporated into the crystal lattice of the minerals. Analysis of aquifer colloids shows that within a 6-month period the average content of Cu and Cd decreased by about 87%. Solid sampling GFAAS was demonstrated to be a convenient method for the study of metal content in small (5 mg) samples of groundwater colloids.

36Cl and 14C analyses of saline groundwater in the Dead Sea area were performed in order to study the chloride source of the brines and their age. Similarity among the 36Cl/Cl ratio in saline groundwater (7−15 × 10−15), Dead Sea water (12.8 × 10−15), and in an halite layer (11 × 10−15) indicates that they all have a similar chloride source. The 36Cl/Cl ratios also suggest a significant contribution of chloride from rain water. It is postulated that groundwater brines are the result of direct infiltration of brines from a precursor Dead Sea lake, such as Lake Lisan, which covered the area in the past. This lake underwent several evaporation stages precipitating halite and infiltrating brines of varying chemical composition. 14C data (3.8–25.8 PMC) indicate that the percolation of brines into the sediments took place more than 9,000 years ago.

The self-diffusion of H 2 18 O has been studied empirically in Dead Sea brine (TDS 340 g/l), a natural, very saline solution composed of mainly Mg and Na chlorides. Experiments were conducted in dialysis cells with 18 O-depleted water at an ambient temperature of 22 ± 1°C. The self-diffusion coefficient in DS water is 1.8 x 10 -5 cm 2 /sec, about 25% lower than the known self-diffusion coefficient in distilled water. Knowledge of the self-diffusion coefficient in hypersaline solutions is of importance for the determination of mass transfer in brines, at sediment-water interfaces in lakes and in interstitial solutions of saturated and unsaturated porous media in aquifers.

Magnetic resonance imaging (MRI) was used to evaluate a column designed to conduct contaminant retardation tests on geological materials under saturated conditions. MRI procedures revealed sediment heterogeneities and preferential flow pathways inherent in the sediments as well as those created in the packing of the column. Sequential MRI images were also used to estimate tracer flow velocities and to detect density flows driven by density differences of as little as 0.0013 g/ml. Interpretation of the images emphasized the importance of small changes in hydraulic conductivity and of column orientation in experiments with fluids of different densities. MRI analysis during column flow experiments holds promise as a measurement technique to estimate retardation factors for selected solutes.

We report here, for the first time, the finding of a 24 to 31 m deep, 10,000 y old, water-saturated and highly hydraulically conductive salt layer composed of idiomorphic halite crystals in the coastal area of the Dead Sea. The high hydraulic conductivity of the layer was evidenced by laboratory and field tests and by the rapid fluctuations of the water table, in a well penetrating the layer, following variations in the water level of the Dead Sea. Such layers may lead to intensive and rapid flow of water and non-polar liquids.

Buoyancy-induced flow (BIF) of both 18O-enriched (δ18O, +160 to +5195‰) and 18O-depleted (δ18O, −500‰) water has been studied in a 10-cm-diameter tube that simulates a section of a well. BIF was detected in all the experiments for a density contrast (Δρ) between 0.03 and 1.0 σ units (equivalent to a total dissolved solids contrast of 30−1000 mg/L). The magnitude of the Rayleigh number suggests that the natural convection flow is turbulent. A mathematical model is presented to predict vertical tracer propagation inside the cavity. The model assumes a local mixing length scale proportional to the tube diameter. A possible transition to the laminar natural convection regime, with a significant reduction in mixing rate compared to that predicted by the model, is detected when the density contrast is reduced to Δρ = 0.03 σ units. This smaller mixing rate is still orders of magnitude larger than diffusion alone. BIF may be an important groundwater transport and mixing mechanism in open conduits in aquifers. Its effects should also be considered when performing tracer experiments in the field.

The water level of the Dead Sea, a terminal hypersaline lake (total dissolved solids, approximately 340 g/L) has decreased at an average rate of 0.5 m/yr since 1960 and by 0.8 m/yr between 1981 and 1989. The dramatic long-term water level variation of the Dead Sea and the seasonal short-term fluctuations are accompanied by parallel variations of groundwater levels in an adjacent aquifer. A general methodology based on a simplified yet reliable one-dimensional flow model, together with continuous measurements of groundwater levels in observation wells, enables analysis of aquifer structural and hydraulic properties. Furthermore, this analysis enables prediction of future groundwater levels in unconfined and confined aquifers due to future changes in lake levels.

The occurrence of 166 emerging compounds and four heavy metals (Cd, Ni, Hg and Pb) in treated wastewater and groundwater has been monitored at the Llobregat delta (Barcelona, Spain) over a period of 3 years. Selected compounds were pharmaceuticals, personal care products (PCPs), dioxins, polycyclic aromatic hydrocarbons (PAHs) and priority substances included in the 2008/105/CE Directive. Analysis was performed in tertiary treated wastewater (TWW), after an additional treatment of ultrafiltration reverse osmosis and UV disinfection, and groundwater from a deep confined aquifer. This aquifer is artificially recharged with TWW through injection wells. After the advanced treatment, 38 pharmaceuticals, 9 PCPs, 9 pesticides and 7 PAHs still showed a frequency of detection higher than 25% in the TWW, although at low concentration levels (ng/l). Not all active compounds found in the TWW were present in groundwater, indicating possible degradation within the aquifer media after the injection. A number of chemicals, mainly 10 pesticides and 10 pharmaceuticals were only present in groundwater samples, confirming a different origin than the injected TWW, probably agricultural activities and/or infiltration of poorly treated wastewater.

Sorption characteristics of four major constituents of sedimentary rocks — quartz, calcite, kaolinite and bentonite — are studied under undisturbed field conditions in the Coastal Plain Aquifer of Israel. Dynamic interaction of minerals with groundwater is indicated by simultaneous enrichment of minerals with respect to certain metals and depletion with respect to others. The distribution coefficient ( D ) is calculated for Ni, Cu, Cr, Co, Fe, Cd, Mn and Pb over a 2-m depth interval in the upper part of the aquifer. The distribution of Fe, Pb and Ni is governed by the surface properties of the minerals. Cd and Mn show a strong affinity for calcite and may be incorporated into calcite grains. Cu and Cr are most effectively sorbed by kaolinite. The suggested experimental approach may be useful for the study of site-specific contamination with hazardous metals.

The immunogenicity of human pluripotent stem cells plays a major role in their potential use in the clinic. We show that, during their reprogramming, human-induced pluripotent stem (iPS) cells downregulate expression of human leukocyte antigen (HLA)-A/B/C and β2 microglobulin (β2M), the two components of major histocompatibility complex-I (MHC-I). MHC-I expression in iPS cells can be restored by differentiation or treatment with interferon-gamma (IFNγ). To analyze the molecular mechanisms that regulate the expression of the MHC-I molecules in human iPS cells, we searched for correlation between the expression of HLA-A/B/C and β2M and the expression of transcription factors that bind to the promoter of these genes. Our results show a significant positive correlation between MHC-I expression and expression of the nuclear factors, nuclear factor kappa B 1 (NFκB1) and RelA, at the levels of RNA, protein and was confirmed by chromatin binding. Concordantly, we detected robust levels of NFκB1 and RelA proteins in the nucleus of somatic cells but not in the iPS cell derived from them. Overexpression of NFκB1 and RelA in undifferentiated pluripotent stem cells led to induction in expression of MHC-I, whereas silencing NFκB1 and RelA by small hairpin RNA decreased the expression of β2M after IFNγ treatment. Our data point to the critical role of NFκB proteins in regulating the MHC-I expression in human pluripotent stem cells.

This study describes the distribution of organic pollutants from the ground surface, through the unsaturated zone, to the water table at a citrus grove irrigated by sewage effluent for about 20 years. The citrus grove, located in Israel, overlies an unconfmed Coastal Plain aquifer about 2 km inland from the Mediterranean Sea. The distribution of organic compounds at the citrus grove is compared with two control sites receiving moisture from nonpolluted water sources (one in another citrus grove irrigated by ground water and the other in an uncultivated area receiving only precipitation). Overall, 10 analyses were performed. At the effluent-irrigated site, organic pollutants from the sewage had migrated through the 20 meter thick unsaturated zone to the water table; included in these were several pollutants, such as toluene and phthalates, that are considered to be biodegradable. Pollutant concentrations generally increased with depth. On the other hand, pollutant concentrations at the two control sites decreased significantly with depth through the unsaturated zone. The downward mobility of organic pollutants may be enhanced by the sewage itself. Because sewage effluent is considered to be a readily available source of irrigation water in many parts of the world, the results of this study suggest that what may seem to be a relatively simple solution to water scarcity problems may have potentially long-term and dangerous effects on ground-water quality.

We discuss the penetration of organic pollutants into the depth of soil and into groundwater under different environmental and geological conditions. In one case a field study was conducted on the impact of prolonged irrigation by effluents on groundwater and vadose zone contamination. The studied site was rich in sandy soil which allowed vertical penetration of pollutants into the depth. A significant difference has been observed in the distribution of organic pollutants in the effluent irrigated site, where the pollution increased markedly while descending from the top soil into the unsaturated zone, compared to the two control sites, where the extent of pollution decreased strongly with the depth. It seems that detergents and other surfactants present in the effluents strongly enhance the transport of organic components via the unsaturated zone. The second case study deals with the transport of organic pollutants in a site where the subsoil is interspaced with clay layers. In this case groundwater pollution derived from the chemical waste of a pesticides plant. A long term follow up of groundwater pollution indicates that the typical contaminant distribution pattern remained unchanged during the years. The pollutants distribution indicates that in this area the penetration of organic pollutants does not occur vertically but rather by horizontal flow, due to inhibition of vertical migration by a thick clay layer present in this area.

Microscale Eulerian variations in the flux, mineralogical composition and size of suspended particles have been found in a contaminated sandy aquifer under natural gradient flow conditions () during an 8 month study period. Particle variability has been detected along a 16 m saturated section of the aquifer at a scale of centimeters and meters in the vertical and horizontal dimensions, respectively. The average concentration of particles in groundwater varied between 1 to 70 mg/l. The particles were primarily composed of CaCO3 (11% to 57%), quartz (7% to 39%) and clays (8% to 43%). Most of the particles were within the 140 to 3,000 nm size range with size modes varying from 310 to 660 nm. The large amounts of suspended particles are considered to be related to high inputs of dissolved organic carbon into groundwater from sewage effluents which have been used for agricultural irrigation since the early 1960's. As a result of organic matter biodegradation in the saturated zone, anoxic conditions developed and the pCO2 content of groundwater increased dramatically. It is postulated that part of the carbonate cement of the rocks dissolved and detrital CaCO3, quartz and clay were released as colloidal particles. In the prevailing anoxic conditions of groundwater at the study site (DO < 1 mg/l) colloidal stability is enhanced by organic matter coating of particles. The transport of metals associated with suspended particles in the saturated zone and the interaction of these particles in the aquifer environment have been ascertained through a comparison of the distribution coefficient of 17 elements as a function of depth. *Contribution No. 61, Department of Environmental Sciences and Energy Research, The Weizmann Institute of Science.

Ground-water management decisions are usually taken under uncertainty, since they depend on unknown parameters of the aquifer such as hydraulic conductivity and specific discharge. This study applies a number of analytical techniques to a case study in order to demonstrate the potential effect of vertical heterogeneity in the horizontal component of specific discharge on evaluating contaminant travel time in an aquifer. The modified point dilution technique developed by Ronen et al. (1986) is applied to study the vertical variability of the horizontal component of specific discharge in a deep unconfined sandy aquifer. This technique, used under natural flow conditions, employs a multilayer sampler, a tracer, and a mathematical diffusion model. Also analyzed are data from a very large unplanned tracer test where the “tracer”, sewage effluent with a high chloride content, was infiltrated into the aquifer for about 30 years. To date, based on available sedimentological evidence and pumping tests, the aquifer has been regarded as homogeneous. However, information from analysis of the tracer test data by two different flow models, and findings obtained by the modified point dilution technique, indicate the existence of zones of high hydraulic conductivity with specific discharges one order of magnitude higher than expected. As a consequence, chloride breakthrough in a pumping well downstream of effluent infiltration was detected after 10 years, at least 70 years earlier than could have been estimated from previously available data. The results demonstrate that consideration must be given to vertical heterogeneity when evaluating contaminant transport and show that detailed site-specific field studies are needed in order to prevent or control aquifer contamination.

We report on two different cases of penetration of organic pollutants deep into the soil and into groundwater. In one event a point source of pollution from a pesticides plant has been studied by a long-term follow-up of a polluted well close to the plant. A typical pattern of pollution has been observed in this well, which was studied for four years. There was a similar organic pollution pattern in soil samples close to the plant. The second case involved an agricultural area long irrigated with effluents. In this area there was an accumulation of organic pollutants deep in the soil (5–20 m depth) and in the groundwater. The mobilizing effect of effluents in promoting the penetration of micropollutants into the depth of soil has been shown. This effect presumably is due to the presence of surface active components. The reported results demonstrate the facile transport of a wide range of xenobiotic organics deep into the soil and into deep groundwater, and advises caution in the use of reclaimed wastewaters for irrigation. © 1993 Wiley-Liss, Inc.