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Sample records for aqp1 water permeability

  1. Cloning and characterization of a zebrafish homologue of human AQP1: a bifunctional water and gas channel

    PubMed Central

    Chen, Li-Ming; Zhao, Jinhua; Musa-Aziz, Raif; Pelletier, Marc F.; Drummond, Iain A.

    2010-01-01

    The mammalian aquaporins AQP1, AQP4, and AQP5 have been shown to function not only as water channels but also as gas channels. Zebrafish have two genes encoding an AQP1 homologue, aqp1a and aqp1b. In the present study, we cloned the cDNA that encodes the zebrafish protein Aqp1a from the 72-h postfertilization (hpf) embryo of Danio rerio, as well as from the swim bladder of the adult. The deduced amino-acid sequence of aqp1a consists of 260 amino acids and is 59% identical to human AQP1. By analyzing the genomic DNA sequence, we identified four exons in the aqp1a gene. By in situ hybridization, aqp1a is expressed transiently in the developing vasculature and in erythrocytes from 16 to 48 h of development. Later, at 72 hpf, aqp1a is expressed in dermal ionocytes and in the swim bladder. Western blot analysis of adult tissues reveals that Aqp1a is most highly expressed in the eye and swim bladder. Xenopus oocytes expressing aqp1a have a channel-dependent (*) osmotic water permeability (Pf*) that is indistinguishable from that of human AQP1. On the basis of the magnitude of the transient change in surface pH (ΔpHS) that were recorded as the oocytes were exposed to either CO2 or NH3, we conclude that zebrafish Aqp1a is permeable to both CO2 and NH3. The ratio (ΔpHS*)CO2/Pf* is about half that of human AQP1, and the ratio (ΔpHS*)NH3/Pf* is about one-quarter that of human AQP1. Thus, compared with human AQP1, zebrafish Aqp1a has about twice the selectivity for CO2 over NH3. PMID:20739606

  2. AQP1 is not only a water channel

    PubMed Central

    2010-01-01

    AQPs are water channel proteins. In particular, AQP1 was demonstrated to be involved in cell migration. According to the model proposed by Verkman and collaborators, AQP drives water influx, facilitating lamellipodia extension and cell migration. Investigating the possible connection between AQP1 and cytoskeleton, our group showed that such a water channel through Lin7/β-catenin affects the organization of the cytoskeleton and proposed a model. All together, these data appear particularly intriguing since the use of AQP1 as target might be useful to modulate angiogenesis/vasculogenic mimicry. PMID:20168076

  3. 6B.06: CARDIAC AQP1 NITROSYLATION IN RESPONSE TO OSMOTIC STRESS INDUCED BY WATER RESTRICTION DURING POSTNATAL GROWTH.

    PubMed

    Netti, V; Iovane, A; Zotta, E; Fellet, A; Balaszczuk, A

    2015-06-01

    Aquaporin-1 (AQP1) is expressed in the heart and it has been reported to transport nitric oxide (NO), an important regulator of cardiac function. Our aim was to study AQP1 abundance and localization, NO synthase (NOS) activity and AQP1 nitrosylation in response to osmotic stress induced by water restriction during postnatal growth. Male Sprague-Dawley rats aged 25 and 50 days (n = 10) were divided in: R: water restriction 3 days; C: water ad libitum 3 days. NOS activity (14C-Arginine), AQP1 protein levels (Western Blot) and localization (immunohistochemistry) and AQP1 nitrosylation (colocalization of immunofluorescence signals of AQP1 and nitrosylated cysteine by confocal microscopy) were determined in cardiac tissue. We also evaluated the effects of NO donor sodium nitroprusside (SNP) on osmotic water permeability of cardiac membrane vesicles expressing AQP1 by stopped-flow spectrometry. Water restriction induced a dehydration state in both age groups. Cardiac AQP1 was localized in the endocardium and endothelium in both age groups in control animals. Water restriction did not change AQP1 abundance or localization in the 25-day-old R group; however, in the 50-day-old group, AQP1 protein levels were increased and immunohistochemistry showed its localization on cardiomyocyte plasma membrane after water restriction. Cardiac NOS activity was increased in the youngest R group but it did not change in the 50-day-old R group. AQP1 nitrosylation was increased in R25 group, whereas there are no significant differences in colocalization of fluorescent signals between C or R animals aged 50 days. On the other hand, cardiac membrane vesicles expressing AQP1 presented a high water permeability coefficient (Pf: 326+/-17 μm/s, n = 6) indicated water transport by aquaporins and pretreatment with SNP decreased water permeability (Pf: 102+/-4 μm/s, n = 5). Cardiac NO system and AQP1 abundance and localization during osmotic stress in vivo depend on postnatal age

  4. Transport of volatile solutes through AQP1

    PubMed Central

    Cooper, Gordon J; Zhou, Yuehan; Bouyer, Patrice; Grichtchenko, Irina I; Boron, Walter F

    2002-01-01

    For almost a century it was generally assumed that the lipid phases of all biological membranes are freely permeable to gases. However, recent observations challenge this dogma. The apical membranes of epithelial cells exposed to hostile environments, such as gastric glands, have no demonstrable permeability to the gases CO2 and NH3. Additionally, the water channel protein aquaporin 1 (AQP1), expressed at high levels in erythrocytes, can increase membrane CO2 permeability when expressed in Xenopus oocytes. Similarly, nodulin-26, which is closely related to AQP1, can act as a conduit for NH3. A key question is whether aquaporins, which are abundant in virtually every tissue that transports O2 and CO2 at high levels, ever play a physiologically significant role in the transport of small volatile molecules. Preliminary data are consistent with the hypothesis that AQP1 enhances the reabsorption of HCO3− by the renal proximal tubule by increasing the CO2 permeability of the apical membrane. Other preliminary data on Xenopus oocytes heterologously expressing the electrogenic Na+-HCO3− cotransporter (NBC), AQP1 and carbonic anhydrases are consistent with the hypothesis that the macroscopic cotransport of Na+ plus two HCO3− occurs as NBC transports Na+ plus CO32- and AQP1 transports CO2 and H2O. Although data – obtained on AQP1 reconstituted into liposomes or on materials from AQP1 knockout mice – appear inconsistent with the model that AQP1 mediates substantial CO2 transport in certain preparations, the existence of unstirred layers or perfusion-limited conditions may have masked the contribution of AQP1 to CO2 permeability. PMID:12096045

  5. Structural basis of water-specific transport through the AQP1 water channel

    NASA Astrophysics Data System (ADS)

    Sui, Haixin; Han, Bong-Gyoon; Lee, John K.; Walian, Peter; Jap, Bing K.

    2001-12-01

    Water channels facilitate the rapid transport of water across cell membranes in response to osmotic gradients. These channels are believed to be involved in many physiological processes that include renal water conservation, neuro-homeostasis, digestion, regulation of body temperature and reproduction. Members of the water channel superfamily have been found in a range of cell types from bacteria to human. In mammals, there are currently 10 families of water channels, referred to as aquaporins (AQP): AQP0-AQP9. Here we report the structure of the aquaporin 1 (AQP1) water channel to 2.2Å resolution. The channel consists of three topological elements, an extracellular and a cytoplasmic vestibule connected by an extended narrow pore or selectivity filter. Within the selectivity filter, four bound waters are localized along three hydrophilic nodes, which punctuate an otherwise extremely hydrophobic pore segment. This unusual combination of a long hydrophobic pore and a minimal number of solute binding sites facilitates rapid water transport. Residues of the constriction region, in particular histidine 182, which is conserved among all known water-specific channels, are critical in establishing water specificity. Our analysis of the AQP1 pore also indicates that the transport of protons through this channel is highly energetically unfavourable.

  6. Aquaporin water channel AgAQP1 in the malaria vector mosquito Anopheles gambiae during blood feeding and humidity adaptation

    PubMed Central

    Liu, Kun; Tsujimoto, Hitoshi; Cha, Sung-Jae; Agre, Peter; Rasgon, Jason L.

    2011-01-01

    Altered patterns of malaria endemicity reflect, in part, changes in feeding behavior and climate adaptation of mosquito vectors. Aquaporin (AQP) water channels are found throughout nature and confer high-capacity water flow through cell membranes. The genome of the major malaria vector mosquito Anopheles gambiae contains at least seven putative AQP sequences. Anticipating that transmembrane water movements are important during the life cycle of A. gambiae, we identified and characterized the A. gambiae aquaporin 1 (AgAQP1) protein that is homologous to AQPs known in humans, Drosophila, and sap-sucking insects. When expressed in Xenopus laevis oocytes, AgAQP1 transports water but not glycerol. Similar to mammalian AQPs, water permeation of AgAQP1 is inhibited by HgCl2 and tetraethylammonium, with Tyr185 conferring tetraethylammonium sensitivity. AgAQP1 is more highly expressed in adult female A. gambiae mosquitoes than in males. Expression is high in gut, ovaries, and Malpighian tubules where immunofluorescence microscopy reveals that AgAQP1 resides in stellate cells but not principal cells. AgAQP1 expression is up-regulated in fat body and ovary by blood feeding but not by sugar feeding, and it is reduced by exposure to a dehydrating environment (42% relative humidity). RNA interference reduces AgAQP1 mRNA and protein levels. In a desiccating environment (<20% relative humidity), mosquitoes with reduced AgAQP1 protein survive significantly longer than controls. These studies support a role for AgAQP1 in water homeostasis during blood feeding and humidity adaptation of A. gambiae, a major mosquito vector of human malaria in sub-Saharan Africa. PMID:21444767

  7. Aquaporin water channel AgAQP1 in the malaria vector mosquito Anopheles gambiae during blood feeding and humidity adaptation.

    PubMed

    Liu, Kun; Tsujimoto, Hitoshi; Cha, Sung-Jae; Agre, Peter; Rasgon, Jason L

    2011-04-12

    Altered patterns of malaria endemicity reflect, in part, changes in feeding behavior and climate adaptation of mosquito vectors. Aquaporin (AQP) water channels are found throughout nature and confer high-capacity water flow through cell membranes. The genome of the major malaria vector mosquito Anopheles gambiae contains at least seven putative AQP sequences. Anticipating that transmembrane water movements are important during the life cycle of A. gambiae, we identified and characterized the A. gambiae aquaporin 1 (AgAQP1) protein that is homologous to AQPs known in humans, Drosophila, and sap-sucking insects. When expressed in Xenopus laevis oocytes, AgAQP1 transports water but not glycerol. Similar to mammalian AQPs, water permeation of AgAQP1 is inhibited by HgCl(2) and tetraethylammonium, with Tyr185 conferring tetraethylammonium sensitivity. AgAQP1 is more highly expressed in adult female A. gambiae mosquitoes than in males. Expression is high in gut, ovaries, and Malpighian tubules where immunofluorescence microscopy reveals that AgAQP1 resides in stellate cells but not principal cells. AgAQP1 expression is up-regulated in fat body and ovary by blood feeding but not by sugar feeding, and it is reduced by exposure to a dehydrating environment (42% relative humidity). RNA interference reduces AgAQP1 mRNA and protein levels. In a desiccating environment (<20% relative humidity), mosquitoes with reduced AgAQP1 protein survive significantly longer than controls. These studies support a role for AgAQP1 in water homeostasis during blood feeding and humidity adaptation of A. gambiae, a major mosquito vector of human malaria in sub-Saharan Africa.

  8. The aquaporin TcAQP1 of the desert truffle Terfezia claveryi is a membrane pore for water and CO(2) transport.

    PubMed

    Navarro-Ródenas, Alfonso; Ruíz-Lozano, Juan Manuel; Kaldenhoff, Ralf; Morte, Asunción

    2012-02-01

    Terfezia claveryi is a hypogeous mycorrhizal fungus belonging to the so-called "desert truffles," with a good record as an edible fungus and of considerable economic importance. T. claveryi improves the tolerance to water stress of the host plant Helianthemum almeriense, for which, in field conditions, symbiosis with T. claveryi is valuable for its survival. We have characterized cDNAs from T. claveryi and identified a sequence related to the aquaporin gene family. The full-length sequence was obtained by rapid amplification of cDNA ends and was named TcAQP1. This aquaporin gene encoded a functional water-channel protein, as demonstrated by heterologous expression assays in Saccharomyces cerevisiae. The mycorrhizal fungal aquaporin increased both water and CO(2) conductivity in the heterologous expression system. The expression patterns of the TcAQP1 gene in mycelium, under different water potentials, and in mycorrhizal plants are discussed. The high levels of water conductivity of TcAQP1 could be related to the adaptation of this mycorrhizal fungus to semiarid areas. The CO(2) permeability of TcAQP1 could be involved in the regulation of T. claveryi growth during presymbiotic phases, making it a good candidate to be considered a novel molecular signaling channel in mycorrhizal fungi.

  9. Organ-Specific Splice Variants of Aquaporin Water Channel AgAQP1 in the Malaria Vector Anopheles gambiae

    PubMed Central

    Tsujimoto, Hitoshi; Liu, Kun; Linser, Paul J.; Agre, Peter; Rasgon, Jason L.

    2013-01-01

    Background Aquaporin (AQP) water channels are important for water homeostasis in all organisms. Malaria transmission is dependent on Anopheles mosquitoes. Water balance is a major factor influencing mosquito survival, which may indirectly affect pathogen transmission. Methodology/Principal Findings We obtained full-length mRNA sequences for Anopheles gambiae aquaporin 1 (AgAQP1) and identified two splice variants for the gene. In vitro expression analysis showed that both variants transported water and were inhibited by Hg2+. One splice variant (AgAQP1A) was exclusively expressed in adult female ovaries indicating a function in mosquito reproduction. The other splice variant (AgAQP1B) was expressed in the midgut, malpighian tubules and the head in adult mosquitoes. Immunolabeling showed that in malpighian tubules, AgAQP1 is expressed in principal cells in the proximal portion and in stellate cells in the distal portion. Moreover, AgAQP1 is expressed in Johnston’s organ (the “ear”), which is important for courtship behavior. Conclusions And Significance These results suggest that AgAQP1 may play roles associated with mating (courtship) and reproduction in addition to water homeostasis in this important African malaria vector. PMID:24066188

  10. Osmotic water permeability diversification in primary trophoblast cultures from aquaporin 1-deficient pregnant mice.

    PubMed

    Sha, Xiao-Yan; Liu, Hui-Shu; Ma, Tong-Hui

    2015-09-01

    Aquaporins (AQP) are water channel proteins, and some play an important role in maternal-fetal fluid exchange. The present study aimed to measure the osmotic water permeability in primary cultures of trophoblast cells from AQP1-deficient (AQP1(-/-) ) pregnant mice and to define the quantitative role of AQP1 in water transport across the trophoblast plasma membrane. Trophoblast cells were obtained from placental tissue cell culture of AQP1(-/-) pregnant mice and were characterized by cytokeratin 7 immunostaining. The expression of the AQP1 gene in trophoblast cells of wild-type (AQP1(+/+) ) mice was confirmed by immunofluorescence. The osmotic water permeability of trophoblast plasma membranes was measured by a calcein fluorescence quenching method in response to osmotic gradients. A primary cell culture system for trophoblasts was successfully established. Immunofluorescence showed the expression of AQP1 in the trophoblast cell membrane of AQP1(+/+) mice. The osmotic water permeability of AQP1(-/-) trophoblast cells was significantly lower than that in AQP1(+/+) trophoblast cells, in response to both hypotonic and hypertonic challenges. The results suggest an important role of AQP1-mediated plasma membrane water permeability in maternal-fetal fluid balance and also provide a potential direction for the identification of therapeutic targets for the treatment of abnormalities in amniotic fluid volume. © 2015 Japan Society of Obstetrics and Gynecology.

  11. Very high aquaporin-1 facilitated water permeability in mouse gallbladder

    PubMed Central

    Li, Lihua; Zhang, Hua; Ma, Tonghui; Verkman, A. S.

    2009-01-01

    Water transport across gallbladder epithelium is driven by osmotic gradients generated from active salt absorption and secretion. Aquaporin (AQP) water channels have been proposed to facilitate transepithelial water transport in gallbladder and to modulate bile composition. We found strong AQP1 immunofluorescence at the apical membrane of mouse gallbladder epithelium. Transepithelial osmotic water permeability (Pf) was measured in freshly isolated gallbladder sacs from the kinetics of luminal calcein self-quenching in response to an osmotic gradient. Pf was very high (0.12 cm/s) in gallbladders from wild-type mice, cAMP independent, and independent of osmotic gradient size and direction. Although gallbladders from AQP1 knockout mice had similar size and morphology to those from wild-type mice, their Pf was reduced by ∼10-fold. Apical plasma membrane water permeability was greatly reduced in AQP1-deficient gallbladders, as measured by cytoplasmic calcein quenching in perfluorocarbon-filled, inverted gallbladder sacs. However, neither bile osmolality nor bile salt concentration differed in gallbladders from wild-type vs. AQP1 knockout mice. Our data indicate constitutively high water permeability in mouse gallbladder epithelium involving transcellular water transport through AQP1. The similar bile salt concentration in gallbladders from AQP1 knockout mice argues against a physiologically important role for AQP1 in mouse gallbladder. PMID:19179619

  12. Transgenic Expression of AQP1 in the Fiber Cells of AQP0 Knockout Mouse: Effects on Lens Transparency

    PubMed Central

    Varadaraj, K.; Kumari, S.S.; Mathias, R.T.

    2010-01-01

    Mutations and knockout of aquaporin 0 (AQP0) result in dominant lens cataract. To date, several functions have been proposed for AQP0; however, two functions, water permeability and cell-to-cell adhesion have been supported by several investigators and only water channel function has been readily authenticated by in vitro and ex vivo studies. Lens shifts protein expression from the more efficient AQP1 in the equatorial epithelial cells to the less efficient water channel, AQP0, in the differentiating secondary fiber cells; perhaps, AQP0 performs a distinctive function. If AQP0 has only water permeability function, can the more efficient water channel AQP1 transgenically expressed in the fiber cells compensate and restore lens transparency in the AQP0 knockout (AQP0-/-) mouse? To investigate, we generated a transgenic wild type mouse line expressing AQP1 in the fiber cells using αA-crystallin promoter. These transgenic mice (TgAQP1+/+) showed increase in fiber cell membrane water permeability without any morphological, anatomical or physiological defects compared to the wild type indicating that the main purpose of the shift in expression from AQP1 to AQP0 may not be to lessen the membrane water permeability. Further, we transgenically expressed AQP1 in the lens fiber cells of AQP0 knockout mouse (TgAQP1+/+/AQP0-/-) to determine whether AQP1 could restore AQP0 water channel function and regain lens transparency. Fiber cells of these mice showed 2.6 times more water permeability than the wild type. Transgene AQP1 reduced the severity of lens cataract and prevented dramatic acceleration of cataractogenesis. However, lens fiber cells showed deformities and lack of compact cellular architecture. Loss of lens transparency due to the absence of AQP0 was not completely restored indicating an additional function for AQP0. In vitro studies showed that AQP0 is capable of cell-to-cell adhesion while AQP1 is not. To our knowledge, this is the first report which uses an animal

  13. Novel Endothelial Cell-Specific AQP1 Knockout Mice Confirm the Crucial Role of Endothelial AQP1 in Ultrafiltration during Peritoneal Dialysis.

    PubMed

    Zhang, Wei; Freichel, Marc; van der Hoeven, Frank; Nawroth, Peter Paul; Katus, Hugo; Kälble, Florian; Zitron, Edgar; Schwenger, Vedat

    2016-01-01

    The water channel aquaporin-1 (AQP1) mediates about 50% ultrafiltration during a 2-hour hypertonic dwell in global AQP1 knockout (AQP1-/-) mice. Although AQP1 is widely expressed in various cell types including mesothelial cells, the ultrafiltration has been assumed to be mediated via endothelial AQP1 of the peritoneum. The partial embryonic lethality and reduced body weight in AQP1-/- mice may reflect potential confounding phenotypic effects evoked by ubiquitous AQP1 deletion, which may interfere with functional analysis of endothelial AQP1. Using a Cre/loxP approach, we generated and characterised endothelial cell- and time-specific AQP1 knockout (AQP1fl/fl; Cdh5-Cre+) mice. Compared to controls, AQP1fl/fl; Cdh5-Cre+ mice showed no difference in an initial clinical and biological analysis at baseline, including body weight and survival. During a 1-hour 3.86% mini-peritoneal equilibration test (mini-PET), AQP1fl/fl; Cdh5-Cre+ mice exhibited strongly decreased indices for AQP1-related transcellular water transport (43.0% in net ultrafiltration, 93.0% in sodium sieving and 57.9% in free water transport) compared to controls. The transport rates for small solutes of urea and glucose were not significantly altered. Our data provide the first direct experimental evidence for the functional relevance of endothelial AQP1 to the fluid transport in peritoneal dialysis and thereby further validate essential predictions of the three-pore model of peritoneal transport.

  14. Expression of aquaporin 1 (AQP1) in human synovitis.

    PubMed

    Mobasheri, Ali; Moskaluk, Christopher A; Marples, David; Shakibaei, Mehdi

    2010-04-20

    Rheumatoid arthritis (RA) is an autoimmune disorder characterized by synovial proliferation (synovitis), articular cartilage and subchondral bone degradation as well as joint swelling. Joint swelling and edema often accompany pannus formation and chronic joint inflammation in RA. We have recently shown that human chondrocytes and synoviocytes express aquaporin 1 (AQP1) water channels and that AQP1 is upregulated in RA cartilage. Clinical evidence suggests that joint swelling and edema accompany the chronic inflammation observed in synovial joints of RA patients. Therefore we hypothesized that AQP1 water channels may be involved in joint swelling and synovial edema formation. To test this hypothesis, we performed immunostaining of normal and human synovitis tissue microarrays (TMAs) to investigate whether the expression of AQP1 water channels is altered in the synovium in synovitis. Immunohistochemistry revealed that AQP1 is expressed in synovial micro-vessels and synoviocytes from normal joints (n=20 normal subjects). Semi-quantitative histomorphometric analysis of AQP1 expression in the TMAs revealed upregulation of the membrane protein in the synovium derived from RA (n=10) and psoriatic arthritis (n=8) patients. These results indicate a potential role for synovial AQP1 and other aquaporins in joint swelling and the vasogenic edema fluid formation and hydrarthrosis associated with synovial inflammation. Future experiments will need to determine whether the expression of other aquaporins is altered in synovitis. Copyright 2010 Elsevier GmbH. All rights reserved.

  15. Aquaporin deletion in mice reduces corneal water permeability and delays restoration of transparency after swelling.

    PubMed

    Thiagarajah, Jay R; Verkman, A S

    2002-05-24

    Two aquaporin (AQP)-type water channels are expressed in mammalian cornea, AQP1 in endothelial cells and AQP5 in epithelial cells. To test whether these aquaporins are involved in corneal fluid transport and transparency, we compared corneal thickness, water permeability, and response to experimental swelling in wild type mice and transgenic null mice lacking AQP1 and AQP5. Corneal thickness in fixed sections was remarkably reduced in AQP1 null mice and increased in AQP5 null mice. By z-scanning confocal microscopy, corneal thickness in vivo was (in microm, mean +/- S.E., n = 5 mice) 123 +/- 1 (wild type), 101 +/- 2 (AQP1 null), and 144 +/- 2 (AQP5 null). After exposure of the external corneal surface to hypotonic saline (100 mosm), the rate of corneal swelling (5.0 +/- 0.3 microm/min, wild type) was reduced by AQP5 deletion (2.7 +/- 0.1 microm/min). After exposure of the endothelial surface to hypotonic saline by anterior chamber perfusion, the rate of corneal swelling (7.1 +/- 1.0 microm/min, wild type) was reduced by AQP1 deletion (1.6 +/- 0.4 microm/min). Base-line corneal transparency was not impaired by AQP1 or AQP5 deletion. However, the recovery of corneal transparency and thickness after hypotonic swelling (10-min exposure of corneal surface to hypotonic saline) was remarkably delayed in AQP1 null mice with approximately 75% recovery at 7 min in wild type mice compared with 5% recovery in AQP1 null mice. Our data indicate that AQP1 and AQP5 provide the principal routes for corneal water transport across the endothelial and epithelial barriers, respectively. The impaired recovery of corneal transparency in AQP1 null mice provides evidence for the involvement of AQP1 in active extrusion of fluid from the corneal stroma across the corneal endothelium. The up-regulation of AQP1 expression and/or function in corneal endothelium may reduce corneal swelling and opacification following injury.

  16. Role of Aquaporin-4 in Airspace-to-Capillary Water Permeability in Intact Mouse Lung Measured by a Novel Gravimetric Method

    PubMed Central

    Song, Yuanlin; Ma, Tonghui; Matthay, Michael A.; Verkman, A.S.

    2000-01-01

    The mammalian peripheral lung contains at least three aquaporin (AQP) water channels: AQP1 in microvascular endothelia, AQP4 in airway epithelia, and AQP5 in alveolar epithelia. In this study, we determined the role of AQP4 in airspace-to-capillary water transport by comparing water permeability in wild-type mice and transgenic null mice lacking AQP1, AQP4, or AQP1/AQP4 together. An apparatus was constructed to measure lung weight continuously during pulmonary artery perfusion of isolated mouse lungs. Osmotically induced water flux (Jv) between the airspace and capillary compartments was measured from the kinetics of lung weight change in saline-filled lungs in response to changes in perfusate osmolality. Jv in wild-type mice varied linearly with osmotic gradient size (4.4 × 10−5 cm3 s−1 mOsm−1) and was symmetric, independent of perfusate osmolyte size, weakly temperature dependent, and decreased 11-fold by AQP1 deletion. Transcapillary osmotic water permeability was greatly reduced by AQP1 deletion, as measured by the same method except that the airspace saline was replaced by an inert perfluorocarbon. Hydrostatically induced lung edema was characterized by lung weight changes in response to changes in pulmonary arterial inflow or pulmonary venous outflow pressure. At 5 cm H2O outflow pressure, the filtration coefficient was 4.7 cm3 s−1 mOsm−1 and reduced 1.4-fold by AQP1 deletion. To study the role of AQP4 in lung water transport, AQP1/AQP4 double knockout mice were generated by crossbreeding of AQP1 and AQP4 null mice. Jv were (cm3 s−1 mOsm−1 × 10−5, SEM, n = 7–12 mice): 3.8 ± 0.4 (wild type), 0.35 ± 0.02 (AQP1 null), 3.7 ± 0.4 (AQP4 null), and 0.25 ± 0.01 (AQP1/AQP4 null). The significant reduction in Pf in AQP1 vs. AQP1/AQP4 null mice was confirmed by an independent pleural surface fluorescence method showing a 1.6 ± 0.2-fold (SEM, five mice) reduced Pf in the AQP1/AQP4 double knockout mice vs. AQP1 null mice. These results establish a

  17. Increased Expression of AQP 1 and AQP 5 in Rat Lungs Ventilated with Low Tidal Volume is Time Dependent

    PubMed Central

    Fabregat, Gustavo; García-de-la-Asunción, José; Sarriá, Benjamín; Cortijo, Julio; De Andrés, José; Mata, Manuel; Pastor, Ernesto; Belda, Francisco Javier

    2014-01-01

    Background and Goals Mechanical ventilation (MV) can induce or worsen pulmonary oedema. Aquaporins (AQPs) facilitate the selective and rapid bi-directional movement of water. Their role in the development and resolution of pulmonary oedema is controversial. Our objectives are to determine if prolonged MV causes lung oedema and changes in the expression of AQP 1 and AQP 5 in rats. Methods 25 male Wistar rats were subjected to MV with a tidal volume of 10 ml/kg, during 2 hours (n = 12) and 4 hours (n = 13). Degree of oedema was compared with a group of non-ventilated rats (n = 5). The expression of AQP 1 and AQP 5 were determined by western immunoblotting, measuring the amount of mRNA (previously amplified by RT-PCR) and immunohistochemical staining of AQPs 1 and 5 in lung samples from all groups. Results Lung oedema and alveolar-capillary membrane permeability did not change during MV. AQP-5 steady state levels in the western blot were increased (p<0.01) at 2 h and 4 h of MV. But in AQP-1 expression these differences were not found. However, the amount of mRNA for AQP-1 was increased at 2 h and 4 h of MV; and for AQP 5 at 4 h of MV. These findings were corroborated by representative immunohistochemical lung samples. Conclusion In lungs from rats ventilated with a low tidal volume the expression of AQP 5 increases gradually with MV duration, but does not cause pulmonary oedema or changes in lung permeability. AQPs may have a protective effect against the oedema induced by MV. PMID:25489856

  18. Water permeability through aquaporin-4 is regulated by protein kinase C and becomes rate-limiting for glioma invasion.

    PubMed

    McCoy, E S; Haas, B R; Sontheimer, H

    2010-07-28

    Glial-derived tumors, gliomas, are highly invasive cancers that invade normal brain through the extracellular space. To navigate the tortuous extracellular spaces, cells undergo dynamic changes in cell volume, which entails water flux across the membrane through aquaporins (AQPs). Two members of this family, AQP1 and AQP4 are highly expressed in primary brain tumor biopsies and both have a consensus phosphorylation site for protein kinase C (PKC), which is a known regulator of glioma cell invasion. AQP4 colocalizes with PKC to the leading edge of invading processes and clustered with chloride channel (ClC2) and K(+)-Cl(-) cotransporter 1 (KCC1), believed to provide the pathways for Cl(-) and K(+) secretion to accomplish volume changes. Using D54MG glioma cells stably transfected with either AQP1 or AQP4, we show that PKC activity regulates water permeability through phosphorylation of AQP4. Activation of PKC with either phorbol 12-myristate 13-acetate or thrombin enhanced AQP4 phosphorylation, reduced water permeability and significantly decreased cell invasion. Conversely, inhibition of PKC activity with chelerythrine reduced AQP4 phosphorylation, enhanced water permeability and significantly enhanced tumor invasion. PKC regulation of AQP4 was lost after mutational inactivation of the consensus PKC phosphorylation site S180A. Interestingly, AQP1 expressing glioma cells, by contrast, were completely unaffected by changes in PKC activity. To demonstrate a role for AQPs in glioma invasion in vivo, cells selectively expressing AQP1, AQP4 or the mutated S180A-AQP4 were implanted intracranially into SCID mice. AQP4 expressing glioma cells showed significantly reduced invasion compared to AQP1 and S180 expressing tumors as determined by quantitative stereology, consistent with a differential role for AQP1 and AQP4 in this process. Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  19. Silicic acid in drinking water prevents age-related alterations in the endothelium-dependent vascular relaxation modulating eNOS and AQP1 expression in experimental mice: an immunohistochemical study.

    PubMed

    Buffoli, Barbara; Foglio, Eleonora; Borsani, Elisa; Exley, Christopher; Rezzani, Rita; Rodella, Luigi Fabrizio

    2013-06-01

    The maintenance of endothelial integrity is of great importance in coping with age-related vascular alterations. Endothelium-derived nitric oxide is one of the various vasoactive substances able to regulate vascular tone and homeostasis, and whose decrease is known to be related with senescence in endothelial cells. There are reports on the efficacy of silicon, especially as silicic acid, in protecting vascular integrity during age-related vascular diseases. The aim of this study was to evaluate the ability of supplementation of silicic acid in drinking water in the maintenance of vascular health in a mouse model of early physiological aging. In particular, we evaluated the relationship between Si supplementation and endothelial nitric oxide synthase (eNOS) expression, taking into account also the aquaporin-1 (AQP-1) isoform that, as recently reported, seems to be involved in nitric oxide transport across cell membranes. Our results showed that silicic acid supplementation increased both eNOS and AQP-1 expression, suggesting that silicic acid modulation of endothelial nitric oxide synthase and aquaporin-1 could represent a potential strategy against age-related vascular senescence. Copyright © 2012 Elsevier GmbH. All rights reserved.

  20. Water Transport in Aquaporins: Osmotic Permeability Matrix Analysis of Molecular Dynamics Simulations

    PubMed Central

    Hashido, Masanori; Kidera, Akinori; Ikeguchi, Mitsunori

    2007-01-01

    Single-channel osmotic water permeability (pf) is a key quantity for investigating the transport capability of the water channel protein, aquaporin. However, the direct connection between the single scalar quantity pf and the channel structure remains unclear. In this study, based on molecular dynamics simulations, we propose a pf-matrix method, in which pf is decomposed into contributions from each local region of the channel. Diagonal elements of the pf matrix are equivalent to the local permeability at each region of the channel, and off-diagonal elements represent correlated motions of water molecules in different regions. Averaging both diagonal and off-diagonal elements of the pf matrix recovers pf for the entire channel; this implies that correlated motions between distantly-separated water molecules, as well as adjacent water molecules, influence the osmotic permeability. The pf matrices from molecular dynamics simulations of five aquaporins (AQP0, AQP1, AQP4, AqpZ, and GlpF) indicated that the reduction in the water correlation across the Asn-Pro-Ala region, and the small local permeability around the ar/R region, characterize the transport efficiency of water. These structural determinants in water permeation were confirmed in molecular dynamics simulations of three mutants of AqpZ, which mimic AQP1. PMID:17449664

  1. Increased water flux induced by an aquaporin-1/carbonic anhydrase II interaction

    PubMed Central

    Vilas, Gonzalo; Krishnan, Devishree; Loganathan, Sampath Kumar; Malhotra, Darpan; Liu, Lei; Beggs, Megan Rachele; Gena, Patrizia; Calamita, Giuseppe; Jung, Martin; Zimmermann, Richard; Tamma, Grazia; Casey, Joseph Roman; Alexander, Robert Todd

    2015-01-01

    Aquaporin-1 (AQP1) enables greatly enhanced water flux across plasma membranes. The cytosolic carboxy terminus of AQP1 has two acidic motifs homologous to known carbonic anhydrase II (CAII) binding sequences. CAII colocalizes with AQP1 in the renal proximal tubule. Expression of AQP1 with CAII in Xenopus oocytes or mammalian cells increased water flux relative to AQP1 expression alone. This required the amino-terminal sequence of CAII, a region that binds other transport proteins. Expression of catalytically inactive CAII failed to increase water flux through AQP1. Proximity ligation assays revealed close association of CAII and AQP1, an effect requiring the second acidic cluster of AQP1. This motif was also necessary for CAII to increase AQP1-mediated water flux. Red blood cell ghosts resealed with CAII demonstrated increased osmotic water permeability compared with ghosts resealed with albumin. Water flux across renal cortical membrane vesicles, measured by stopped-flow light scattering, was reduced in CAII-deficient mice compared with wild-type mice. These data are consistent with CAII increasing water conductance through AQP1 by a physical interaction between the two proteins. PMID:25609088

  2. AQUAPORIN-1 WATER PERMEABILITY AS A NOVEL DETERMINANT OF AXONAL REGENERATION IN DORSAL ROOT GANGLION NEURONS

    PubMed Central

    Zhang, Hua; Verkman, A.S.

    2015-01-01

    Dorsal root ganglion (DRG) neurons transduce peripheral pain signals through small-diameter, non-myelinated C-fibers, which, when injured, can regenerate to restore pain sensation. Water channel aquaporin-1 (AQP1) is expressed at the plasma membrane of cell bodies and axons of DRG neurons, where it modulates the sensing of certain types of pain. Here, we found that AQP1 is also involved in DRG axonal growth and regeneration by a mechanism that may involve water transport-facilitated extension of axonal outgrowths. Spontaneous and nerve growth factor-stimulated axonal extension was reduced in cultures of AQP1-deficient DRG neurons and DRG explants compared to the wildtype. Axonal growth in AQP1-deficient DRG cultures was rescued by transfection with AQP1 or a different water-transporting AQP (AQP4), but not by a non-water-transporting AQP1 mutant. Following sciatic nerve compression injury AQP1 expression was increased in DRG neurons in wildtype mice, and DRG axonal growth was impaired in AQP1-deficient mice. Our results indicate AQP1 as a novel determinant of DRG axonal regeneration and hence a potential therapeutic target to accelerate neuronal regeneration. PMID:25585012

  3. Aquaporin-1 water permeability as a novel determinant of axonal regeneration in dorsal root ganglion neurons.

    PubMed

    Zhang, Hua; Verkman, A S

    2015-03-01

    Dorsal root ganglion (DRG) neurons transduce peripheral pain signals through small-diameter, non-myelinated C-fibers, which, when injured, can regenerate to restore pain sensation. Water channel aquaporin-1 (AQP1) is expressed at the plasma membrane of cell bodies and axons of DRG neurons, where it modulates the sensing of certain types of pain. Here, we found that AQP1 is also involved in DRG axonal growth and regeneration by a mechanism that may involve water transport-facilitated extension of axonal outgrowths. Spontaneous and nerve growth factor-stimulated axonal extension was reduced in cultures of AQP1-deficient DRG neurons and DRG explants compared to the wildtype. Axonal growth in AQP1-deficient DRG cultures was rescued by transfection with AQP1 or a different water-transporting AQP (AQP4), but not by a non-water-transporting AQP1 mutant. Following sciatic nerve compression injury AQP1 expression was increased in DRG neurons in wildtype mice, and DRG axonal growth was impaired in AQP1-deficient mice. Our results indicate AQP1 as a novel determinant of DRG axonal regeneration and hence a potential therapeutic target to accelerate neuronal regeneration. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Adenovirus-mediated hAQP1 expression in irradiated mouse salivary glands causes recovery of saliva secretion by enhancing acinar cell volume decrease.

    PubMed

    Teos, L Y; Zheng, C-Y; Liu, X; Swaim, W D; Goldsmith, C M; Cotrim, A P; Baum, B J; Ambudkar, I S

    2016-07-01

    Head and neck irradiation (IR) during cancer treatment causes by-stander effects on the salivary glands leading to irreversible loss of saliva secretion. The mechanism underlying loss of fluid secretion is not understood and no adequate therapy is currently available. Delivery of an adenoviral vector encoding human aquaporin-1 (hAQP1) into the salivary glands of human subjects and animal models with radiation-induced salivary hypofunction leads to significant recovery of saliva secretion and symptomatic relief in subjects. To elucidate the mechanism underlying loss of salivary secretion and the basis for AdhAQP1-dependent recovery of salivary gland function we assessed submandibular gland function in control mice and mice 2 and 8 months after treatment with a single 15-Gy dose of IR (delivered to the salivary gland region). Salivary secretion and neurotransmitter-stimulated changes in acinar cell volume, an in vitro read-out for fluid secretion, were monitored. Consistent with the sustained 60% loss of fluid secretion following IR, a carbachol (CCh)-induced decrease in acinar cell volume from the glands of mice post IR was transient and attenuated as compared with that in cells from non-IR age-matched mice. The hAQP1 expression in non-IR mice induced no significant effect on salivary fluid secretion or CCh-stimulated cell volume changes, except in acinar cells from 8-month group where the initial rate of cell shrinkage was increased. Importantly, the expression of hAQP1 in the glands of mice post IR induced recovery of salivary fluid secretion and a volume decrease in acinar cells to levels similar to those in cells from non-IR mice. The initial rates of CCh-stimulated cell volume reduction in acinar cells from hAQP1-expressing glands post IR were similar to those from control cells. Altogether, the data suggest that expression of hAQP1 increases the water permeability of acinar cells, which underlies the recovery of fluid secretion in the salivary glands

  5. Role of AQP1 in inner ear in motion sickness.

    PubMed

    Huang, Yi-Deng; Xia, Si-Wen; Dai, Pu; Han, Dong-Yi

    2011-10-24

    Inner ear is critical for the development of motion sickness (MS). The present work was designed to test the role of aquaporins (AQPs) in inner ear in MS. After repetitive stimulus of rotation, the MS symptom was steadily alleviated in mice. After repetitive stimulus of rotation, several AQPs mRNA levels including AQP1, AQP2, AQP3, AQP4, AQP6, AQP7, and AQP9 in the inner ears of mice were analyzed. It was found that AQP1 mRNA level was increased remarkably, which was reconfirmed by Western blotting analysis. In addition, the relationship between AQP1 expression and MS sensitivity was studied and it was shown that AQP1 mRNA level was negatively related to MS index in mice. We sought to examine the function of AQP1 in inner ear using an RNAi approach to reduce the AQP1 protein expression in vivo. It was first observed that AQP1 knockdown in inner ear resulted in a significant increase of MS sensitivity in mice. In conclusion, after repetitive stimulus of rotation, the alleviation of MS symptom in mice was, at least in part, due to the upregulation of AQP1 expression in inner ear. In addition, the sensitivity to MS in mice was, at least in part, dependent on the expression of AQP1 in inner ear. AQP1 in inner ear plays an important role in the development of MS, and might be a potential target for the prevention or management of MS. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Direct visualization of the arterial wall water permeability barrier using CARS microscopy.

    PubMed

    Lucotte, Bertrand M; Powell, Chloe; Knutson, Jay R; Combs, Christian A; Malide, Daniela; Yu, Zu-Xi; Knepper, Mark; Patel, Keval D; Pielach, Anna; Johnson, Errin; Borysova, Lyudmyla; Dora, Kim A; Balaban, Robert S

    2017-05-02

    The artery wall is equipped with a water permeation barrier that allows blood to flow at high pressure without significant water leak. The precise location of this barrier is unknown despite its importance in vascular function and its contribution to many vascular complications when it is compromised. Herein we map the water permeability in intact arteries, using coherent anti-Stokes Raman scattering (CARS) microscopy and isotopic perfusion experiments. Generation of the CARS signal is optimized for water imaging with broadband excitation. We identify the water permeation barrier as the endothelial basolateral membrane and show that the apical membrane is highly permeable. This is confirmed by the distribution of the AQP1 water channel within endothelial membranes. These results indicate that arterial pressure equilibrates within the endothelium and is transmitted to the supporting basement membrane and internal elastic lamina macromolecules with minimal deformation of the sensitive endothelial cell. Disruption of this pressure transmission could contribute to endothelial cell dysfunction in various pathologies.

  7. Fourfold reduction of water permeability in inner medullary collecting duct of aquaporin-4 knockout mice.

    PubMed

    Chou, C L; Ma, T; Yang, B; Knepper, M A; Verkman, A S

    1998-02-01

    Aquaporin (AQP)-3 and AQP4 water channels are expressed at the basolateral membrane of mammalian collecting duct epithelium. To determine the contribution of AQP4 to water permeability in the initial inner medullary collecting duct (IMCD), osmotic water permeability (Pf) was compared in isolated perfused IMCD segments from wild-type and AQP4 knockout mice. The AQP4 knockout mice were previously found to have normal gross appearance, survival, growth, and kidney morphology and a mild urinary concentrating defect (T. Ma, B. Yang, A. Gillespie, E. J. Carlson, C. J. Epstein, and A. S. Verkman, J. Clin. Invest. 100: 957-962, 1997). Transepithelial Pf was measured in microdissected IMCDs after 18-48 h of water deprivation and in the presence of 0.1 nM arginine vasopressin (to make basolateral Pf rate limiting). Pf values (37 degrees C; means +/- SE in cm/s x 10(-3)) were 56.0 +/- 8.5 for wild-type mice (n = 5) and 13.1 +/- 3.7 for knockout mice (n = 6) (P < 0.001). Northern blot analysis of kidney showed that transcript expression of AQP1, AQP2, AQP3, and AQP6 were not affected by AQP4 deletion. Immunoblot analysis indicated no differences in protein expression of AQP1, AQP2, or AQP3, and immunoperoxidase showed no differences in staining patterns. Coexpression of AQP3 and AQP4 in Xenopus laevis oocytes showed additive water permeabilities, suggesting that AQP4 deletion does not affect AQP3 function. These results indicate that AQP4 is responsible for the majority of basolateral membrane water movement in IMCD but that its deletion is associated with a very mild defect in urinary concentrating ability.

  8. Involvement of AQP 1 in the cardio-protective effect of remifentanil post-conditioning in ischemia/reperfusion rats

    PubMed Central

    Lin, Peng-Tao; Chen, Wen-Hua; Zheng, Hong; Lai, Zhong-Meng; Zhang, Liang-Cheng

    2015-01-01

    Background: our research aim to study the role of AQP1 in the cardioprotective effect of remifentanil post-conditioning for myocardial ischemia/reperfusion injury. Methods: Ninety Sprague-Dawley (SD) rats were divided into 6 groups: sham operation group (Sham group), myocardial ischemia and reperfusion group (I/R group), postconditioning of remifentanil group (R-post), postconditioning of remifentanil plus AQP1 inhibitor acetazolamide group (R-post +Ace), postconditioning of remifentanil plus opioid-receptor antagonist compounds (R-post +AC), postconditioning of remifentanil plus AQP1 enhancer arginine vasopressin (R-post +AV). All groups except the sham operation group were given 30 min ischemia in left anterior descending (LAD) coronary arteries. All groups were then given 120 min reperfusion to the LAD. Before reperfusion, the R-post, R-post +Ace, R-post +AC, R-post +AV groups were given 10 min remifentanil post-conditioning. Hemodynamic data were measured every 30 min after initiation of ischemia. The rats’ hearts were exercised for detecting infarct size and water content in the left ventricle, and AQP1 expression were also detected. Results: The R-post group showed a significant reduction of the infarct size compared to the I/R group. The effect of R-post for reducing infarct size was slightly enhanced by adding acetazolamide to R-post, so significant differences could still be found when compared R-post+Ace group to the I/R group. The effect of infarct size reduction brought by R-post was blocked by the opioid-receptor antagonist compounds. This effect was also blocked by the AQP1 enhancer. Similar outcomes were found considering the water content of the left ventricle and the AQP1 expression. Conclusion: Cardioprotective effect of remifentanil post-conditioning may initiate through inhibiting the function of AQP1. PMID:26550187

  9. Prolonged Starvation Causes Up-Regulation of AQP1 in Adipose Tissue Capillaries of AQP7 Knock-Out Mice

    PubMed Central

    Skowronski, Mariusz T.; Skowronska, Agnieszka; Rojek, Aleksandra; Oklinski, Michal K.; Nielsen, Søren

    2016-01-01

    Aquaporins (AQPs) are membrane proteins involved in the regulation of cellular transport and the balance of water and glycerol and cell volume in the white adipose tissue (WAT). In our previous study, we found the co-expression of the AQP1 water channel and AQP7 in the mouse WAT. In our present study, we aimed to find out whether prolonged starvation influences the AQP1 expression of AQP7 knock-out mice (AQP7 KO) in the WAT. To resolve this hypothesis, immunoperoxidase, immunoblot and immunogold microscopy were used. AQP1 expression was found with the use of immunohistochemistry and was confirmed by immunogold microscopy in the vessels of mouse WAT of all studied groups. Semi-quantitative immunoblot and quantitative immunogold microscopy showed a significant increase (by 2.5- to 3-fold) in the abundance of AQP1 protein expression in WAT in the 72 h starved AQP7 KO mice as compared to AQP7+/+ (p < 0.05) and AQP7−/− (p < 0.01) controls, respectively. In conclusion, the AQP1 water channel located in the vessels of WAT is up-regulated in response to prolonged starvation in the WAT of AQP7 KO mice. The present data suggest that an interaction of different AQP isoforms is required for maintaining proper water homeostasis within the mice WAT. PMID:27455244

  10. Steam-water relative permeability

    SciTech Connect

    Ambusso, W.; Satik, C.; Home, R.N.

    1997-12-31

    A set of relative permeability relations for simultaneous flow of steam and water in porous media have been measured in steady state experiments conducted under the conditions that eliminate most errors associated with saturation and pressure measurements. These relations show that the relative permeabilities for steam-water flow in porous media vary approximately linearly with saturation. This departure from the nitrogen/water behavior indicates that there are fundamental differences between steam/water and nitrogen/water flows. The saturations in these experiments were measured by using a high resolution X-ray computer tomography (CT) scanner. In addition the pressure gradients were obtained from the measurements of liquid phase pressure over the portions with flat saturation profiles. These two aspects constitute a major improvement in the experimental method compared to those used in the past. Comparison of the saturation profiles measured by the X-ray CT scanner during the experiments shows a good agreement with those predicted by numerical simulations. To obtain results that are applicable to general flow of steam and water in porous media similar experiments will be conducted at higher temperature and with porous rocks of different wetting characteristics and porosity distribution.

  11. Partial Least-Squares Functional Mode Analysis: Application to the Membrane Proteins AQP1, Aqy1, and CLC-ec1

    PubMed Central

    Krivobokova, Tatyana; Briones, Rodolfo; Hub, Jochen S.; Munk, Axel; de Groot, Bert L.

    2012-01-01

    We introduce an approach based on the recently introduced functional mode analysis to identify collective modes of internal dynamics that maximally correlate to an external order parameter of functional interest. Input structural data can be either experimentally determined structure ensembles or simulated ensembles, such as molecular dynamics trajectories. Partial least-squares regression is shown to yield a robust solution to the multidimensional optimization problem, with a minimal and controllable risk of overfitting, as shown by extensive cross-validation. Several examples illustrate that the partial least-squares-based functional mode analysis successfully reveals the collective dynamics underlying the fluctuations in selected functional order parameters. Applications to T4 lysozyme, the Trp-cage, the aquaporin channels Aqy1 and hAQP1, and the CLC-ec1 chloride antiporter are presented in which the active site geometry, the hydrophobic solvent-accessible surface, channel gating dynamics, water permeability (pf), and a dihedral angle are defined as functional order parameters. The Aqy1 case reveals a gating mechanism that connects the inner channel gating residues with the protein surface, thereby providing an explanation of how the membrane may affect the channel. hAQP1 shows how the pf correlates with structural changes around the aromatic/arginine region of the pore. The CLC-ec1 application shows how local motions of the gating Glu148 couple to a collective motion that affects ion affinity in the pore. PMID:22947940

  12. A new AQP1 null allele identified in a Gypsy woman who developed an anti-CO3 during her first pregnancy

    PubMed Central

    Saison, Carole; Peyrard, Thierry; Landre, Caroline; Ballif, Bryan A.; Schlosser, Kate A.; Dettori, Isabelle; Chicheportiche, Colette; Nemeth, Peter; Cartron, Jean-Pierre; Arnaud, Lionel

    2014-01-01

    Background and Objectives The Colton blood group antigens are carried by the AQP1 water channel. AQP1−/− individuals, also known as Colton-null since they express no Colton antigens, do not suffer any apparent clinical consequence but may develop a clinically significant alloantibody (anti-CO3) induced by transfusion or pregnancy. Identification and transfusion support of Colton-null patients are highly challenging, not only due to the extreme rarity of this phenotype, the lack of appropriate reagents in most laboratories, as well as the possibility of confusing its with the recently described CO:-1,-2,3,-4 phenotype where AQP1 is present. This study investigated a new Colton-null case and evaluated three commercially available anti-AQP1s to identify Colton-null red blood cell samples. Methods The Colton-null phenotype was investigated by standard serological techniques, AQP1 sequencing, immunoblot and flow cytometry analyses. Results We identified and characterized the Colton-null phenotype in a Gypsy woman who developed an anti-CO3 during her first pregnancy. After developing a simple and robust method to sequence AQP1, we showed that she was apparently homozygous for a new AQP1 null allele, AQP1 601delG, whose product is not expressed in her red blood cells. We also established the Colton specificity of three commercially available anti-AQP1s in immunoblot and/or flow cytometry analyses. Conclusion This Gypsy woman represents the sixth Colton-null case characterized at the serological, genetic and biochemical levels. The validation here of new reagents and methods should facilitate the identification of Colton-null individuals. PMID:22348807

  13. Hypothyroidism increases osmotic water permeability (Pf) in the developing renal brush border membrane.

    PubMed

    Mulder, Jaap; Haddad, Maha N; Vernon, Kimberly; Baum, Michel; Quigley, Raymond

    2003-06-01

    The osmotic water permeability (Pf) of the rabbit proximal tubule brush border membrane vesicles (BBMV) increases during maturation and is mediated by an increase in aquaporin-1 (AQP1) protein expression. Serum thyroid hormone levels increase after birth and have been shown to play a role in the maturation of other renal transport functions. We examined the hypothesis that thyroid hormone plays a role in the maturational increase in osmotic water permeability. Hypothyroidism was induced by addition of 0.1% propylthiouracil (PTU) to the drinking water of pregnant rabbits (starting 9 d before delivery) and was continued until the rabbits were studied as adults (9-11 wk). Some animals received thyroid hormone replacement by daily injection with triiodothyronine (T3; 10 microg/100 g body weight) for three days before study. Pf was found to be higher in BBMV from hypothyroid (82.7 +/- 5.5 microm/s) than from euthyroid (60.6 +/- 4.0 microm/s) and T3-replacement rabbits (69.0 +/- 5.0 microm/s) (p < 0.05). The activation energy (Ea; in kcal/deg.mol) of Pf was not different among the three experimental groups (euthyroid 5.6 +/- 0.9, hypothyroid 4.9 +/- 0.8, T3-replacement 5.0 +/- 1.0; p = NS), nor was the percentage mercury inhibition of Pf (euthyroid 66.5 +/- 5.3, hypothyroid 74.2 +/- 3.2 and T3-replacement 73.1 +/- 4.3; p = NS). AQP1 expression, measured by immunoblotting, was highest in BBMV from hypothyroid rabbits (p < 0.05). Membrane fluidity, measured as steady-state generalized polarization (GP) of Laurdan, which is inversely related to membrane fluidity, was significantly different between the three groups (GP: euthyroid 0.307 +/- 0.004, hypothyroid 0.271 +/- 0.004 and T3-replacement 0.287 +/- 0.003; for all p < 0.05). These data demonstrate that the maturational increase in thyroid hormone levels is not responsible for the maturational increase in water transport. Surprisingly, congenital hypothyroidism in rabbits is associated with an increased Pf when rabbits

  14. Direct visualization of the arterial wall water permeability barrier using CARS microscopy

    PubMed Central

    Lucotte, Bertrand M.; Powell, Chloe; Knutson, Jay R.; Combs, Christian A.; Malide, Daniela; Yu, Zu-Xi; Knepper, Mark; Patel, Keval D.; Pielach, Anna; Johnson, Errin; Borysova, Lyudmyla; Balaban, Robert S.

    2017-01-01

    The artery wall is equipped with a water permeation barrier that allows blood to flow at high pressure without significant water leak. The precise location of this barrier is unknown despite its importance in vascular function and its contribution to many vascular complications when it is compromised. Herein we map the water permeability in intact arteries, using coherent anti-Stokes Raman scattering (CARS) microscopy and isotopic perfusion experiments. Generation of the CARS signal is optimized for water imaging with broadband excitation. We identify the water permeation barrier as the endothelial basolateral membrane and show that the apical membrane is highly permeable. This is confirmed by the distribution of the AQP1 water channel within endothelial membranes. These results indicate that arterial pressure equilibrates within the endothelium and is transmitted to the supporting basement membrane and internal elastic lamina macromolecules with minimal deformation of the sensitive endothelial cell. Disruption of this pressure transmission could contribute to endothelial cell dysfunction in various pathologies. PMID:28373558

  15. Inhibition of the expression of aquaporin‑1 by RNA interference in pulmonary epithelial cells and its effects on water transport.

    PubMed

    Zhang, Qiuyue; Fu, Jianhua; Xue, Xindong

    2016-01-01

    In the present study, the effect of aquaporin‑1 (AQP1) on fluid transportation in pulmonary epithelial cells, and the role of AQP1 in alveolar fluid clearance were investigated to provide an experimental foundation to elucidate the pathogenesis of hyperoxic lung edema. An siRNA transfection technique was used to silence AQP1 in the A549 cell line. The transfected cells were randomized into a hyperoxia exposure and an air control group, with a negative control group set for each group. Cell volume was determined using flow cytometry, and Pf values were used to determine osmotic water permeability. Cell volume was found to be reduced in the AQP1‑silenced A549 cells, compared with the negative control group 72 h following air exposure. In addition, cell volume was reduced in the AQP1‑silenced A549 cells, compared with the negative control group 48 and 72 h following hyperoxia exposure. The osmotic water permeability of the AQP1‑silenced cells was reduced in the air control and hyperoxia exposure groups, compared with the negative control group 48 and 72 h following exposure. The volume and cell membrane osmotic water permeability of the A549 cells were reduced, compared with those in the control group following AQP1‑silencing, which indicated that the downregulation of AQP1 impedes extracellular to intracellular fluid transportation. Therefore, the disturbance in alveolar fluid clearance resulting from the downregulation of AQP1 following hyperoxia exposure may be one of the key mechanisms responsible for hyperoxic lung edema.

  16. Aquaporin-1 in the peritoneal membrane: Implications for water transport across capillaries and peritoneal dialysis.

    PubMed

    Devuyst, Olivier; Ni, Jie

    2006-08-01

    Peritoneal dialysis (PD) is an established mode of renal replacement therapy, based on the exchange of fluid and solutes between blood in peritoneal capillaries and a dialysate that has been introduced in the peritoneal cavity. The dialysis involves diffusive and convective transports and osmosis through the highly vascularized peritoneal membrane. Computer simulations predicted that the membrane contains ultrasmall pores (radius < 3 A) responsible for the transport of solute-free water across the capillary endothelium during crystalloid osmosis. The distribution of the water channel aquaporin-1 (AQP1), as well as its molecular structure ensuring an exquisite selectivity for water perfectly fit with the characteristics of the ultrasmall pore. Treatment with corticosteroids induces the expression of AQP1 in peritoneal capillaries and increases water permeability and ultrafiltration in rats, without affecting the osmotic gradient and the permeability for small solutes. Studies in knockout mice provided further evidence that osmotically-driven water transport across the peritoneal membrane is mediated by AQP1. AQP1 and endothelial NO synthase (eNOS) show a distinct regulation within the endothelium lining peritoneal capillaries. In acute peritonitis, the upregulation of eNOS and increased release of NO dissipate the osmotic gradient and result in ultrafiltration failure, despite the unchanged expression of AQP1. These data illustrate the potential of the peritoneal membrane to investigate the role and regulation of AQP1 in the endothelium. They also emphasize the critical role of AQP1 during peritoneal dialysis and suggest that manipulating AQP1 expression may be used to increase water permeability across the peritoneal membrane.

  17. Impairment of NtAQP1 gene expression in tobacco plants does not affect root colonisation pattern by arbuscular mycorrhizal fungi but decreases their symbiotic efficiency under drought.

    PubMed

    Porcel, Rosa; Gómez, Manuel; Kaldenhoff, Ralf; Ruiz-Lozano, Juan Manuel

    2005-09-01

    We investigated in two tobacco (Nicotiana tabacum) plant lines (wildtype or antisense mutant) whether impairment in expression of the plasma membrane aquaporin gene (NtAQP1) affects the arbuscular mycorrhizal (AM) fungal colonisation pattern or the symbiotic efficiency of AM fungi. These two objectives were investigated under well-watered and drought stress conditions. Both plant lines had a similar pattern of root colonisation under well-watered and drought stress conditions. In contrast, under drought stress, AM wildtype plants grew faster than mycorrhizal antisense plants. Plant gas exchange also appeared to depend on the expression of NtAQP1 and parallelled the determined growth increments. The implications of enhanced symplastic water transport via NtAQP1 for the efficiency of the AM symbiosis under drought stress conditions are further discussed.

  18. Molecular Basis of pH and Ca2+ Regulation of Aquaporin Water Permeability

    PubMed Central

    Németh-Cahalan, Karin L.; Kalman, Katalin; Hall, James E.

    2004-01-01

    Aquaporins facilitate the diffusion of water across cell membranes. We previously showed that acid pH or low Ca2+ increase the water permeability of bovine AQP0 expressed in Xenopus oocytes. We now show that external histidines in loops A and C mediate the pH dependence. Furthermore, the position of histidines in different members of the aquaporin family can “tune” the pH sensitivity toward alkaline or acid pH ranges. In bovine AQP0, replacement of His40 in loop A by Cys, while keeping His122 in loop C, shifted the pH sensitivity from acid to alkaline. In the killifish AQP0 homologue, MIPfun, with His at position 39 in loop A, alkaline rather than acid pH increased water permeability. Moving His39 to His40 in MIPfun, to mimic bovine AQP0 loop A, shifted the pH sensitivity back to the acid range. pH regulation was also found in two other members of the aquaporin family. Alkaline pH increased the water permeability of AQP4 that contains His at position 129 in loop C. Acid and alkaline pH sensitivity was induced in AQP1 by adding histidines 48 (in loop A) and 130 (in loop C). We conclude that external histidines in loops A and C that span the outer vestibule contribute to pH sensitivity. In addition, we show that when AQP0 (bovine or killifish) and a crippled calmodulin mutant were coexpressed, Ca2+ sensitivity was lost but pH sensitivity was maintained. These results demonstrate that Ca2+ and pH modulation are separable and arise from processes on opposite sides of the membrane. PMID:15078916

  19. Permeability of cork for water and ethanol.

    PubMed

    Fonseca, Ana Luisa; Brazinha, Carla; Pereira, Helena; Crespo, Joao G; Teodoro, Orlando M N D

    2013-10-09

    Transport properties of natural (noncompressed) cork were evaluated for water and ethanol in both vapor and liquid phases. The permeability for these permeants has been measured, as well as the sorption and diffusion coefficients. This paper focuses on the differences between the transport of gases' relevant vapors and their liquids (water and ethanol) through cork. A transport mechanism of vapors and liquids is proposed. Experimental evidence shows that both vapors and liquids permeate not only through the small channels across the cells (plasmodesmata), as in the permeation of gases, but also through the walls of cork cells by sorption and diffusion as in dense membranes. The present study also shows that cork permeability for gases was irreversibly and drastically decreased after cork samples were exposed to ethanol or water in liquid phase.

  20. Effect of water on hydrogen permeability

    NASA Technical Reports Server (NTRS)

    Hulligan, David; Tomazic, William A.

    1987-01-01

    Doping of hydrogen with CO and CO2 was developed to reduce hydrogen permeation in Stirling engines by forming a low permeability oxide coating on the inner surface of the heater head tubes. Although doping worked well, under certain circumstances the protective oxide could be chemically reduced by the hydrogen in the engine. Some oxygen is required in the hydrogen to prevent reduction. Eventually, all the oxygen in the hydrogen gas - whatever its source - shows up as water. This is the result of hydrogen reducing the CO, CO2, or the protective inner surface oxides. This water can condense in the engine system under the right conditions. If the concentration of water vapor is reduced to a low enough level, the hydrogen can chemically reduce the oxide coating, resulting in an increase in permeability. This work was done to define the minimum water content required to avoid this reduction in the oxide coating. The results of this testing show that a minimum of approximately 750 ppm water is required to prevent an increase in permeability of CG-27, a high temperature metal alloy selected for Stirling engine heater tubes.

  1. Subcellular localization of selectively permeable aquaporins in the male germ line of a marine teleost reveals spatial redistribution in activated spermatozoa.

    PubMed

    Chauvigné, François; Boj, Mónica; Vilella, Sebastiano; Finn, Roderick Nigel; Cerdà, Joan

    2013-08-01

    In oviparous vertebrates such as the marine teleost gilthead seabream, water and fluid homeostasis associated with testicular physiology and the external activation of spermatozoa is potentially mediated by multiple aquaporins. To test this hypothesis, we isolated five novel members of the aquaporin superfamily from gilthead seabream and developed paralog-specific antibodies to localize the cellular sites of protein expression in the male reproductive tract. Together with phylogenetic classification, functional characterization of four of the newly isolated paralogs, Aqp0a, -7, -8b, and -9b, demonstrated that they were water permeable, while Aqp8b was also permeable to urea, and Aqp7 and -9b were permeable to glycerol and urea. Immunolocalization experiments indicated that up to seven paralogous aquaporins are differentially expressed in the seabream testis: Aqp0a and -9b in Sertoli and Leydig cells, respectively; Aqp1ab, -7, and -10b from spermatogonia to spermatozoa; and Aqp1aa and -8b in spermatids and sperm. In the efferent duct, only Aqp10b was found in the luminal epithelium. Ejaculated spermatozoa showed a segregated spatial distribution of five aquaporins: Aqp1aa and -7 in the entire flagellum or the head, respectively, and Aqp1ab, -8b, and -10b both in the head and the anterior tail. The combination of immunofluorescence microscopy and biochemical fractionation of spermatozoa indicated that Aqp10b and phosphorylated Aqp1ab are rapidly translocated to the head plasma membrane upon activation, whereas Aqp8b accumulates in the mitochondrion of the spermatozoa. In contrast, Aqp1aa and -7 remained unchanged. These data reveal that aquaporin expression in the teleost testis shares conserved features of the mammalian system, and they suggest that the piscine channels may play different roles in water and solute transport during spermatogenesis, sperm maturation and nutrition, and the initiation and maintenance of sperm motility.

  2. Water permeability of spider dragline silk.

    PubMed

    Li, Xiang; Eles, Philip T; Michal, Carl A

    2009-05-11

    The water permeability of spider dragline silk was studied by measuring changes in amide deuteration of D(2)O-soaked silk with solid-state NMR. (13)C-D rotational-echo double-resonance (REDOR) NMR experiments showed that chemical exchange of amide hydrogen occurs in a large fraction of amino acids, including over 50% of alanine residues, which are known to exist predominantly in beta-sheet crystallites. This suggests that a substantial fraction of the crystalline regions are permeable to water, at least on the time scale of hours, implying that they are more dynamic, and therefore susceptible to chemical exchange with water, than previously thought. Wideline deuterium NMR spectra of dried D(2)O-soaked silk showed a combination of quadrupolar broadened and motionally averaged isotropic components whose intensities change on the time scale of hours. These results are interpreted in terms of chemical exchange between deuterium on the protein backbone, residual water within the silk, and water vapor in the ambient atmosphere. A simple compartmental model fits the results well and yields rate constants for the exchange processes. The model requires the inclusion of a compartment that does not undergo exchange. This compartment, likely related to the crystalline region, is interesting because it is accessible to water in wet silk, but impervious to any remaining free water when the silk is dried.

  3. Osmotic water permeability of human red cells

    PubMed Central

    1981-01-01

    The osmotic water permeability of human red cells has been reexamined with a stopped-flow device and a new perturbation technique. Small osmotic gradients are used to minimize the systematic error caused by nonlinearities in the relationship between cell volume and light scattering. Corrections are then made for residual systematic error. Our results show that the hydraulic conductivity, Lp, is essentially independent of the direction of water flow and of osmolality in the range 184-365 mosM. the mean value of Lp obtained obtained was 1.8 +/- 0.1 (SEM) X 10-11 cm3 dyne -1 s-1. PMID:7229611

  4. Aquaporin water channels – from atomic structure to clinical medicine

    PubMed Central

    Agre, Peter; King, Landon S; Yasui, Masato; Guggino, Wm B; Ottersen, Ole Petter; Fujiyoshi, Yoshinori; Engel, Andreas; Nielsen, Søren

    2002-01-01

    The water permeability of biological membranes has been a longstanding problem in physiology, but the proteins responsible for this remained unknown until discovery of the aquaporin 1 (AQP1) water channel protein. AQP1 is selectively permeated by water driven by osmotic gradients. The atomic structure of human AQP1 has recently been defined. Each subunit of the tetramer contains an individual aqueous pore that permits single-file passage of water molecules but interrupts the hydrogen bonding needed for passage of protons. At least 10 mammalian aquaporins have been identified, and these are selectively permeated by water (aquaporins) or water plus glycerol (aquaglyceroporins). The sites of expression coincide closely with the clinical phenotypes – ranging from congenital cataracts to nephrogenic diabetes insipidus. More than 200 members of the aquaporin family have been found in plants, microbials, invertebrates and vertebrates, and their importance to the physiology of these organisms is being uncovered. PMID:12096044

  5. An AQP1 null allele in an Indian woman with Co(a-b-) phenotype and high-titer anti-Co3 associated with mild HDN.

    PubMed

    Joshi, S R; Wagner, F F; Vasantha, K; Panjwani, S R; Flegel, W A

    2001-10-01

    The Colton blood group system (CO, ISBT 015) is composed of three antigens, of which Co3 (ISBT 015.003) is carried by almost all persons, except those of the extremely rare Co(a-b-) phenotype. The Colton blood group antigens are expressed by the water channel aquaporin 1 (aqp1; also known as channel-forming integral protein, CHIP-28), which is a highly conserved RBC integral membrane protein. The two most frequent alleles, CO1 and CO2, encode the antigens Co(a) and Co(b), respectively. Four null alleles have been described for the AQP1 gene to date. An Indian woman had an alloimmune antibody to an high-frequency antigen associated with mild HDN. Her RBCs were typed Co(a--b-), and the antibody was an anti-Co3. She typed CO1-positive and CO2-negative in a new genotyping method, using PCR with sequence-specific priming, for CO1 and CO2. A method for nucleotide sequencing of the four AQP1 exons from genomic DNA was developed. The patient was shown to be homozygous for a nonfunctional allele AQP1(232delG) that also carried the CO1-specific polymorphism. The kindred presented a fifth example of an AQP1 null allele, which was caused by a single nucleotide deletion leading to a shift in the reading frame beyond codon 78. A method of genotyping CO for Co(a) and Co(b) antigen phenotype prediction was presented.

  6. Endothelial cell permeability to water and antipyrine

    SciTech Connect

    Garrick, R.A.

    1986-03-05

    The endothelium provides a structural barrier between plasma constituents and the tissues. The permeability characteristics of the the endothelial cells regulate the transcellular movement of materials across this barrier while other movement is paracellular. In this study the permeability of the endothelial cells to tritiated water (/sup 3/HHO) and /sup 14/C-labeled antipyrine (AP) was investigated. The cells were isolated non-enzymatically from calf pulmonary artery and were maintained in culture and used between the seventh and fifteenth passage. The cells were removed from the T-flasks with a rubber policeman, titurated with a 22g needle and centrifuged. The cells were mixed with an extracellular marker, drawn into polyethylene tubing and packed by centrifugation for use in the linear diffusion technique. All measurements were made at 37 C. The diffusion coefficients for /sup 3/HHO through the packed cells (D), the intracellular material (D/sub 2/), and the extracellular material (D/sub 1/) were 0.682, 0.932 and 2.45 x 10/sup -5/ cm/sup 2/ s/sup -1/ and for AP were 0.273, 0.355 and 1.13 x 10/sup -5/ cm/sup 2/ s/sup -1/ respectively. The permeability coefficient calculated by the series-parallel pathway model for /sup 3/HHO was higher than that for AP and for both /sup 3/HHO and AP were lower than those calculated for isolated lung cells and erythrocytes.

  7. Changes in Air CO2 Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves

    PubMed Central

    Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio

    2016-01-01

    The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO2 concentrations (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO2 concentration ([CO2]) affected net photosynthesis (Pn) and leaf substomatal [CO2] (Ci). Pn was slightly negative at 0 ppm air CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm air [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO2], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the air in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure. PMID:27089333

  8. Comparison of Steady State Method and Transient Methods for Water Permeability Measurement in Low Permeability Rocks

    NASA Astrophysics Data System (ADS)

    Boulin, P. F.; Bretonnier, P.; Gland, N.

    2010-12-01

    Very low permeability geomaterials (order of nanoDarcy (10-21 m2)), such as clays rocks, are studied for many industrial applications such as production from unconventional reserves of oil and gas, CO2 geological storage and deep geological disposal of high-level long-lived nuclear wastes. For these last two applications, clay efficiency as barrier relies mainly on their very low permeability. Laboratory measurement of low permeability to water (below 10-19 m2) remains a technical challenge. Some authors argue that steady state methods are irrelevant due to the time required to stabilize water fluxes in such low permeability media. Most of the authors measuring low permeabilities use a transient technique called pulse decay. This study aims to compare objectively these different types of permeability tests performed on a single clay sample. For the steady state method, a high precision pump was used to impose a pressure gradient and to measure the small resulting water flow rate at steady state. We show that with a suitable set-up, the steady state method enables to measure a very low permeability of 8 10-22 m2 in a period of three days. For a comparable duration, the pulse decay test, most commonly used for such low permeability measurements, provides only an average estimate of the permeability. Permeability measurements by pulse decay require to perform simulations to interpret the pressure relaxation signals. Many uncertainties remain such as the determination of the reservoirs storage factor, micro leakage effect, or the determination of the initial pulse pressure. All these uncertainties have a very significant impact on the determination of sample permeability and specific storage. Opposite to the wide-spread idea that transient techniques are required to measure very low permeability, we show that direct steady state measurement of water permeability with suitable equipments can be much faster and more accurate than measurement by pulse decay, especially in

  9. Experimental water vapor permeability results for common wall materials

    SciTech Connect

    Sipes, J.M.; Hosni, M.H.

    2000-07-01

    This paper presents the experimental water vapor permeability results for gypsum board, latex paint, permeable vinyl wallpaper, vinyl wallpaper, and elastomeric stucco. For each material, a series of modified cup tests was conducted, and the material water vapor permeability was obtained as a function of relative humidity across the specimen. This test method was a modification of the ASTM Standard Test Method E 96-93. The permeability values for the materials tested in this study were compared to the limited available data from literature and were found to be in good agreement.

  10. Diffusional water permeability of human erythrocytes and their ghosts

    PubMed Central

    1982-01-01

    The diffusional water permeability of human red cells and ghosts was determined by measuring the rate of tracer efflux by means of an improved version of the continuous flow tube method, having a time resolution of 2-3 ms. At 25 degrees C, the permeability was 2.4 x 10(3) and 2.9 x 10(3) cm s-1 for red cells and ghosts, respectively. Permeability was affected by neither a change in pH from 5.5 to 9.5, nor by osmolality up to 3.3 osmol. Manganous ions at an extracellular concentration of 19 mM did not change diffusional water permeability, as recently suggested by NMR measurements. A "ground" permeability of 1 x 10(3) cm s-1 was obtained by inhibition with 1 mM of either p- chloromercuribenzoate (PCMB) or p-chloromercuribenzene sulfonate (PCMBS). Inhibition increased temperature dependence of water permeability for red cells and ghosts from 21 to 30 kJ mol-1 to 60 kJ mol-1. Although diffusional water permeability is about one order of magnitude lower than osmotic permeability, inhibition with PCMB and PCMBS, temperature dependence both before and after inhibition, and independence of osmolality showed that diffusional water permeability has qualitative features similar to those reported for osmotic permeability, which indicates that the same properties of the membrane determine both types of transport. It is suggested that the PCMB(S)- sensitive permeability above the ground permeability takes place through the intermediate phase between integral membrane proteins and their surrounding lipids. PMID:7097244

  11. Molecular mechanisms underlying active desalination and low water permeability in the esophagus of eels acclimated to seawater.

    PubMed

    Takei, Yoshio; Wong, Marty K-S; Pipil, Supriya; Ozaki, Haruka; Suzuki, Yutaka; Iwasaki, Wataru; Kusakabe, Makoto

    2017-02-01

    Marine teleosts can absorb imbibed seawater (SW) to maintain water balance, with esophageal desalination playing an essential role. NaCl absorption from luminal SW was enhanced 10-fold in the esophagus of SW-acclimated eels, and removal of Na(+) or Cl(-) from luminal SW abolished the facilitated absorption, indicating coupled transport. Mucosal/serosal application of various blockers for Na(+)/Cl(-) transporters profoundly decreased the absorption. Among the transporter genes expressed in eel esophagus detected by RNA-seq, dimethyl amiloride-sensitive Na(+)/H(+) exchanger (NHE3) and 4,4'-diisothiocyano-2,2'-disulfonic acid-sensitive Cl(-)/[Formula: see text] exchanger (AE) coupled by the scaffolding protein on the apical membrane of epithelial cells, and ouabain-sensitive Na(+)-K(+)-ATPases (NKA1α1c and NKA3α) and diphenylamine-2-carboxylic acid-sensitive Cl(-) channel (CLCN2) on the basolateral membrane, may be responsible for enhanced transcellular NaCl transport because of their profound upregulation after SW acclimation. Upregulated carbonic anhydrase 2a (CA2a) supplies H(+) and [Formula: see text] for activation of the coupled NHE and AE. Apical hydrochlorothiazide-sensitive Na(+)-Cl(-) cotransporters and basolateral Na(+)-[Formula: see text] cotransporter (NBCe1) and AE1 are other possible candidates. Concerning the low water permeability that is typically seen in marine teleost esophagus, downregulated aquaporin genes (aqp1a and aqp3) and upregulated claudin gene (cldn15a) are candidates for transcellular/paracellular route. In situ hybridization showed that these upregulated transporters and tight-junction protein genes were expressed in the absorptive columnar epithelial cells of eel esophagus. These results allow us to provide a full picture of the molecular mechanism of active desalination and low water permeability that are characteristic to marine teleost esophagus and gain deeper insights into the role of gastrointestinal tracts in SW acclimation

  12. PERMEABLE REACTIVE BARRIERS FOR GROUND WATER REMEDIATION

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  13. Permeability assessment of poorly water-soluble compounds under solubilizing conditions: the reciprocal permeability approach.

    PubMed

    Katneni, Kasiram; Charman, Susan A; Porter, Christopher J H

    2006-10-01

    The objective of this study was to develop a general method to assess the intestinal permeability of poorly water-soluble drugs where low-aqueous drug solubility requires conduct of experiments under solubilizing experimental conditions. The permeability (Papp) of diazepam (DIA) was assessed across excised rat jejunum in the absence (Pappcontrol) and presence (Pappuncorr) of polysorbate-80 (PS-80). The micellar association constant (Ka) of DIA, estimated via equilibrium solubility studies, was used to correct Pappuncorr data and obtain an estimate of the true permeability coefficient (Pappcorr). An alternate approach was also developed (the reciprocal permeability approach) to allow direct estimation of Pappcorr without the need for independent estimation of Ka. The approach was further examined experimentally using a range of model drugs. DIA Pappcorr values obtained using the Ka from equilibrium solubility studies deviated from Papp(control) values, especially at PS-80 concentrations above 0.1% w/v. In contrast, data obtained using the reciprocal permeability method were consistent with Pappcontrol across the PS-80 concentration range. Similar trends were observed with propranolol (PRO), antipyrine (ANT), naproxen (NAP), and cinnarizine (CIN). The reciprocal permeability approach therefore provides a simple and accurate method by which the permeability of poorly water-soluble compounds may be estimated under solubilizing conditions.

  14. Expression and Function of Water Channels (Aquaporins) in Migrating Malignant Astrocytes

    PubMed Central

    McCOY, ERIC; SONTHEIMER, HARALD

    2008-01-01

    Aquaporins (AQP) constitute the principal pathway for water movement across biological membranes. Consequently, their expression and function is important for cell volume regulation. Glioma cells quickly adjust their cell volume in response to osmotic challenges or spontaneously as they invade into the narrow and tortuous extracellular spaces of the brain. These cell volume changes are likely to engage water movements across the cell membrane through AQP. AQP expression in glioma cells is poorly understood. In this study, we examined the expression of AQP in several commonly used human glioma cell lines (D54, D65, STTG1, U87, U251) and in numerous acute patient biopsies by PCR, Western blot, and immunocytochemistry and compared them to nonmalignant astrocytes and normal brain. All glioma patient biopsies expressed AQP1, AQP4 and some expressed AQP5. However, when isolated and grown as cell lines they lose all AQP proteins except a few cell lines that maintain expression of AQP1 (D65, U251, GBM62). Reintroducing either AQP1 or AQP4 stably into glioma cell lines allowed us to show that each AQP is sufficient to restore water permeability. Yet, only the presence of AQP1, but not AQP4, enhanced cell growth and migration, typical properties of gliomas, while AQP4 enhanced cell adhesion suggesting differential biological roles for AQP1 and AQP4 in glioma cell biology. PMID:17549682

  15. Regulation of AQP0 water permeability is enhanced by cooperativity.

    PubMed

    Németh-Cahalan, Karin L; Clemens, Daniel M; Hall, James E

    2013-03-01

    Aquaporin 0 (AQP0), essential for lens clarity, is a tetrameric protein composed of four identical monomers, each of which has its own water pore. The water permeability of AQP0 expressed in Xenopus laevis oocytes can be approximately doubled by changes in calcium concentration or pH. Although each monomer pore functions as a water channel, under certain conditions the pores act cooperatively. In other words, the tetramer is the functional unit. In this paper, we show that changes in external pH and calcium can induce an increase in water permeability that exhibits either a positive cooperativity switch-like increase in water permeability or an increase in water permeability in which each monomer acts independently and additively. Because the concentrations of calcium and hydrogen ions increase toward the center of the lens, a concentration signal could trigger a regulatory change in AQP0 water permeability. It thus seems plausible that the cooperative modes of water permeability regulation by AQP0 tetramers mediated by decreased pH and elevated calcium are the physiologically important ones in the living lens.

  16. Chronic Ingestion of High Dosed Phikud Navakot Extraction Induces Mesangiolysis in Rats with Alteration of AQP1 and Hsp60 Expressions

    PubMed Central

    Ampawong, Sumate

    2015-01-01

    Phikud Navakot (PN) is commonly used in Thai traditional medicine for alleviation of cardiovascular and cerebrovascular symptoms; however little is known about the chronic toxicity effects of the extracts from the herbs in PN. Repeated extraction doses of 10, 100, and 1,000 mg/kg/day were randomly administered to both male and female Sprague Dawley rats for 12 months. Histopathological study revealed that mesangiolysis was predominately found at the highest dose. Aquaporin 1 (AQP1) expression in the mesangiolytic glomeruli was significantly lower than in the intact glomeruli. This may be relevant to an imbalance of vascular function manifested by AQP1 alteration. In the mesangiolytic glomeruli, 60 kDa heat shock protein (Hsp60) was significantly upregulated on the endothelial lining cells of aneurysm and vascular cyst. Hsp60 increase may be related to endothelial cell damage due to its intracellular protective role. Blood urea nitrogen and creatinine levels remained within their normal range indicating well-functioning renal reserve function. In conclusion, high dosed PN may affect the endothelium leading to inability of vascular permeability and consequence to mesangiolysis. Our results suggest that only a high dose of chronic oral administration of PN is relatively toxic in association with mesangiolysis. The NOAEL was determined to be 100 mg/kg/day. PMID:25815318

  17. Water retention and gas relative permeability of two industrial concretes

    SciTech Connect

    Chen Wei; Liu Jian; Brue, Flore; Skoczylas, Frederic; Davy, C.A.; Bourbon, Xavier; Talandier, Jean

    2012-07-15

    This experimental study aims at identifying the water retention properties of two industrial concretes to be used for long term underground nuclear waste storage structures. Together with water retention, gas transfer properties are identified at varying water saturation level, i.e. relative gas permeability is assessed directly as a function of water saturation level S{sub w}. The influence of the initial de-sorption path and of the subsequent re-saturation are analysed both in terms of water retention and gas transfer properties. Also, the influence of concrete microstructure upon water retention and relative gas permeability is assessed, using porosity measurements, analysis of the BET theory from water retention properties, and MIP. Finally, a single relative gas permeability curve is proposed for each concrete, based on Van Genuchten-Mualem's statistical model, to be used for continuous modelling approaches of concrete structures, both during drying and imbibition.

  18. Laccaria bicolor aquaporin LbAQP1 is required for Hartig net development in trembling aspen (Populus tremuloides).

    PubMed

    Navarro-RóDenas, Alfonso; Xu, Hao; Kemppainen, Minna; Pardo, Alejandro G; Zwiazek, Janusz J

    2015-11-01

    The development of ectomycorrhizal associations is crucial for growth of many forest trees. However, the signals that are exchanged between the fungus and the host plant during the colonization process are still poorly understood. In this study, we have identified the relationship between expression patterns of Laccaria bicolor aquaporin LbAQP1 and the development of ectomycorrhizal structures in trembling aspen (Populus tremuloides) seedlings. The peak expression of LbAQP1 was 700-fold higher in the hyphae within the root than in the free-living mycelium after 24 h of direct interaction with the roots. Moreover, in LbAQP1 knock-down strains, a non-mycorrhizal phenotype was developed without the Hartig net and the expression of the mycorrhizal effector protein MiSSP7 quickly declined after an initial peak on day 5 of interaction of the fungal hyphae with the roots. The increase in the expression of LbAQP1 required a direct contact of the fungus with the root and it modulated the expression of MiSSP7. We have also determined that LbAQP1 facilitated NO, H2 O2 and CO2 transport when heterologously expressed in yeast. The report demonstrates that the L. bicolor aquaporin LbAQP1 acts as a molecular signalling channel, which is fundamental for the development of Hartig net in root tips of P. tremuloides. © 2015 John Wiley & Sons Ltd.

  19. Determinants of Water Permeability through Nanoscopic Hydrophilic Channels

    PubMed Central

    Portella, Guillem; de Groot, Bert L.

    2009-01-01

    Naturally occurring pores show a variety of polarities and sizes that are presumably directly linked to their biological function. Many biological channels are selective toward permeants similar or smaller in size than water molecules, and therefore their pores operate in the regime of single-file water pores. Intrinsic factors affecting water permeability through such pores include the channel-membrane match, the structural stability of the channel, the channel geometry and channel-water affinity. We present an extensive molecular dynamics study on the role of the channel geometry and polarity on the water osmotic and diffusive permeability coefficients. We show that the polarity of the naturally occurring peptidic channels is close to optimal for water permeation, and that the water mobility for a wide range of channel polarities is essentially length independent. By systematically varying the geometry and polarity of model hydrophilic pores, based on the fold of gramicidin A, the water density, occupancy, and permeability are studied. Our focus is on the characterization of the transition between different permeation regimes in terms of the structure of water in the pores, the average pore occupancy and the dynamics of the permeating water molecules. We show that a general relationship between osmotic and diffusive water permeability coefficients in the single-file regime accounts for the time averaged pore occupancy, and that the dynamics of the permeating water molecules through narrow non single file channels effectively behaves like independent single-file columns. PMID:19186131

  20. Constant-pressure measurement of steam-water relative permeability

    SciTech Connect

    O'Connor, Peter A.

    2001-06-01

    A series of steady-state experiments have established relative permeability curves for two-phase flow of water in a porous medium. These experiments have minimized uncertainty in pressure, heat loss, and saturation. By attempting to maintain a constant pressure gradient, the experiments have provided a baseline from which to determine the effect of temperature on relative permeability. The use of a flexible heater with an automatic control system made it possible to assume negligible phase change for the mobile fluid. X-ray computer tomography (CT) aided by measuring in-situ steam saturation more directly. Mobile steam mass fraction was established by separate steam and water inlets or by correlating with previous results. The measured steam-water relative permeability curves assume a shape similar to those obtained by Corey (1954) for the simultaneous flow of nitrogen and water. Close agreement between the curves by Satik (1998), Mahiya (1999), and this study establishes the reliability of the experimental method and instrumentation adopted in these experiments, though some differences may bear further investigation. In particular, the steam phase relative permeability appears to vary much more linearly with saturation than does the water phase relative permeability.

  1. Testosterone Induces Increase in Aquaporin (AQP)-1, 5, and 7 Expressions in the Uteri of Ovariectomized Rats.

    PubMed

    Salleh, Naguib; Mokhtar, Helmy Mohd; Kassim, Normadiah M; Giribabu, Nelli

    2015-12-01

    Testosterone has been reported to cause a decrease in uterine fluid volume in which this could involve the aquaporins (AQPs). This study aimed to investigate effect of testosterone on uterine AQP-1, 5, and 7 expressions in order to explain the reported reduction in uterine fluid volume under testosterone influence. Ovariectomized adult female rats received peanut oil, testosterone (1 mg/kg/day), estrogen (0.2 µg/kg/day), or combined estrogen plus testosterone for three consecutive days. Other groups received 3 days estrogen followed by 2 days either peanut oil or testosterone with or without flutamide or finasteride. A day after last injection, uteri were harvested, and the levels of AQP-1, 5, and 7 messenger RNA (mRNA) in uterine tissue homogenates were analyzed by real-time PCR (qPCR). Distributions of AQP-1, 5, and 7 proteins in uterus were observed by immunofluorescence. Levels of AQP-1 mRNA were elevated in rats receiving either estrogen or testosterone-only treatment; however, levels of AQP-5 and 7 mRNAs were elevated in rats receiving testosterone-only treatment. In rats pre-treated with estrogen, testosterone treatment resulted in higher AQP-1, 5, and 7 mRNA levels compared to vehicle treatment. Testosterone effects were antagonized by flutamide but not finasteride. Immunofluorescence study showed that AQP-1 was highly distributed in uterine lumenal epithelium following estrogen or testosterone-only treatment. However, AQP-5 and 7 distributions were high in uterine lumenal epithelium following testosterone-only treatment. Testosterone-induced up-regulation of AQP-1, 5, and 7 expressions in uterus could explain the observed reduction in uterine fluid volume as reported under this condition.

  2. AQP1 expression in human gingiva and its correlation with periodontal and peri-implant tissue alterations.

    PubMed

    Buffoli, Barbara; Dalessandri, Michela; Favero, Gaia; Mensi, Magda; Dalessandri, Domenico; Di Rosario, Federico; Stacchi, Claudio; Rezzani, Rita; Salgarello, Stefano; Rodella, Luigi Fabrizio

    2014-06-01

    Aquaporins (AQPs) are a family of hydrophobic integral membrane proteins that function as transmembrane channels and play an important role in tissue homeostasis. Aquaporin-1 (AQP1), in particular, has been reported to be involved in several biological processes including inflammation, angiogenesis, wound healing and others. Periodontitis and peri-implantitis can be defined as inflammatory processes that affect the tissues surrounding a tooth or an osseointegrated implant, respectively. To date, there are limited data about the involvement of AQPs in these diseases. The aim of this study was to evaluate the possible link between the histomorphological alterations and the expression of AQP1 in healthy, pathological and healed periodontal and peri-implant gingival tissues. The results obtained showed that changes in organization of collagen fibers were observed in periodontitis and peri-implantitis, together with an increase in the percentage of area occupied by inflammatory cell infiltration and an increase of AQP1 immunostaining, which was located in the endothelial cells of the vessels within the lamina propria. Moreover, in healed periodontal and peri-implant mucosa a restoration of histomorphological alterations was observed together with a concomitant decrease of AQP1 immunostaining. These data suggested a possible link between the degree of inflammatory state and the presence of AQP1, where the latter could be involved in the chain of inflammatory reactions triggered at periodontal and peri-implant levels.

  3. Desformylgramicidin: a model channel with an extremely high water permeability.

    PubMed Central

    Saparov, S M; Antonenko, Y N; Koeppe, R E; Pohl, P

    2000-01-01

    The water conductivity of desformylgramicidin exceeds the permeability of gramicidin A by two orders of magnitude. With respect to its single channel hydraulic permeability coefficient of 1.1.10(-12) cm(3) s(-1), desformylgramicidin may serve as a model for extremely permeable aquaporin water channel proteins (AQP4 and AQPZ). This osmotic permeability exceeds the conductivity that is predicted by the theory of single-file transport. It was derived from the concentration distributions of both pore-impermeable and -permeable cations that were simultaneously measured by double barreled microelectrodes in the immediate vicinity of a planar bilayer. From solvent drag experiments, approximately five water molecules were found to be transported by a single-file process along with one ion through the channel. The single channel proton, potassium, and sodium conductivities were determined to be equal to 17 pS (pH 2.5), 7 and 3 pS, respectively. Under any conditions, the desformyl-channel remains at least 10 times longer in its open state than gramicidin A. PMID:11053127

  4. Kinetin Increases Water Permeability of Phosphatidylcholine Lipid Bilayers

    PubMed Central

    Stillwell, William; Hester, Paul

    1983-01-01

    Kinetin is shown to increase substantially the water permeability of liposomes composed of several types of phosphatidylcholines including the natural phospholipids egg lecithin and asolectin and the synthetic phospholipids dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine. Kinetin effects were measured from 16.3 micromolar to 2.4 millimolar at temperatures from 10°C to 50°C and at pH 2.0, 7.0, and 11.0. Temperature studies indicate that kinetin produces a larger increase in water permeability with membranes in the more fluid liquid crystalline state. Kinetin is also shown to enhance [14C]glucose permeability and perhaps promotes membrane aggregation. From these experiments, we conclude that kinetin may produce its initial effect by altering the lipid bilayer portion of membranes. PMID:16662860

  5. Water vapor permeability of the rigid-shelled gecko egg.

    PubMed

    Andrews, Robin M

    2012-07-01

    The vast majority of squamate reptiles (lizards and snakes) produce parchment-shelled eggs that absorb water during incubation, and thus increase in mass, volume, and surface area. In contrast, females from a single monophyletic lineage of gekkotan lizards produce rigid-shelled eggs. These eggs are functionally comparable to those of birds, that is, at oviposition, eggs contain all the water needed for development, and their mass decreases during incubation via the diffusion of water vapor through the shell. I determined patterns of water loss and shell permeability to water vapor from oviposition to hatching for the rigid-shelled eggs of the gekkonid Chrondrodactylus turneri and compared permeability of C. turneri eggs to those of birds and other squamates. Chrondrodactylus turneri eggs incubated at 28.5°C and 40% relative humidity (RH) decreased in mass by 14% over the course of a 68-day incubation period. The rate of water loss varied during incubation; egg mass decreased rapidly during the first 8 days of incubation, declined at a low constant rate during the next 35 days, and then decreased rapidly during the final 25 days of incubation. Overall permeability was 0.17 mg/day/kPa/cm(2) . Percent water loss of rigid-shelled gecko eggs during incubation is similar to that exhibited by birds, but water vapor permeability is about one-third that of bird eggs and several orders of magnitude lower than that of parchment-shelled squamate eggs. In general, the water economy of their eggs may be associated with the adaptive radiation of the rigid-shelled sphaerodactylid, phyllodactylid, and gekkonid geckos.

  6. Urban evaporation rates for water-permeable pavements.

    PubMed

    Starke, P; Göbel, P; Coldewey, W G

    2010-01-01

    In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural.

  7. Species-specific antimonial sensitivity in Leishmania is driven by post-transcriptional regulation of AQP1.

    PubMed

    Mandal, Goutam; Mandal, Srotoswati; Sharma, Mansi; Charret, Karen Santos; Papadopoulou, Barbara; Bhattacharjee, Hiranmoy; Mukhopadhyay, Rita

    2015-02-01

    Leishmania is a digenetic protozoan parasite causing leishmaniasis in humans. The different clinical forms of leishmaniasis are caused by more than twenty species of Leishmania that are transmitted by nearly thirty species of phlebotomine sand flies. Pentavalent antimonials (such as Pentostam or Glucantime) are the first line drugs for treating leishmaniasis. Recent studies suggest that pentavalent antimony (Sb(V)) acts as a pro-drug, which is converted to the more active trivalent form (Sb(III)). However, sensitivity to trivalent antimony varies among different Leishmania species. In general, Leishmania species causing cutaneous leishmaniasis (CL) are more sensitive to Sb(III) than the species responsible for visceral leishmaniasis (VL). Leishmania aquaglyceroporin (AQP1) facilitates the adventitious passage of antimonite down a concentration gradient. In this study, we show that Leishmania species causing CL accumulate more antimonite, and therefore exhibit higher sensitivity to antimonials, than the species responsible for VL. This species-specific differential sensitivity to antimonite is directly proportional to the expression levels of AQP1 mRNA. We show that the stability of AQP1 mRNA in different Leishmania species is regulated by their respective 3'-untranslated regions. The differential regulation of AQP1 mRNA explains the distinct antimonial sensitivity of each species.

  8. Species-Specific Antimonial Sensitivity in Leishmania Is Driven by Post-Transcriptional Regulation of AQP1

    PubMed Central

    Mandal, Goutam; Mandal, Srotoswati; Sharma, Mansi; Charret, Karen Santos; Papadopoulou, Barbara; Bhattacharjee, Hiranmoy; Mukhopadhyay, Rita

    2015-01-01

    Leishmania is a digenetic protozoan parasite causing leishmaniasis in humans. The different clinical forms of leishmaniasis are caused by more than twenty species of Leishmania that are transmitted by nearly thirty species of phlebotomine sand flies. Pentavalent antimonials (such as Pentostam or Glucantime) are the first line drugs for treating leishmaniasis. Recent studies suggest that pentavalent antimony (Sb(V)) acts as a pro-drug, which is converted to the more active trivalent form (Sb(III)). However, sensitivity to trivalent antimony varies among different Leishmania species. In general, Leishmania species causing cutaneous leishmaniasis (CL) are more sensitive to Sb(III) than the species responsible for visceral leishmaniasis (VL). Leishmania aquaglyceroporin (AQP1) facilitates the adventitious passage of antimonite down a concentration gradient. In this study, we show that Leishmania species causing CL accumulate more antimonite, and therefore exhibit higher sensitivity to antimonials, than the species responsible for VL. This species-specific differential sensitivity to antimonite is directly proportional to the expression levels of AQP1 mRNA. We show that the stability of AQP1 mRNA in different Leishmania species is regulated by their respective 3’-untranslated regions. The differential regulation of AQP1 mRNA explains the distinct antimonial sensitivity of each species. PMID:25714343

  9. Intrachromosomal Amplification, Locus Deletion and Point Mutation in the Aquaglyceroporin AQP1 Gene in Antimony Resistant Leishmania (Viannia) guyanensis

    PubMed Central

    Monte-Neto, Rubens; Laffitte, Marie-Claude N.; Leprohon, Philippe; Reis, Priscila; Frézard, Frédéric; Ouellette, Marc

    2015-01-01

    Background Antimony resistance complicates the treatment of infections caused by the parasite Leishmania. Methodology/Principal Findings Using next generation sequencing, we sequenced the genome of four independent Leishmania guyanensis antimony-resistant (SbR) mutants and found different chromosomal alterations including aneuploidy, intrachromosomal gene amplification and gene deletion. A segment covering 30 genes on chromosome 19 was amplified intrachromosomally in three of the four mutants. The gene coding for the multidrug resistance associated protein A involved in antimony resistance was also amplified in the four mutants, most likely through chromosomal translocation. All mutants also displayed a reduced accumulation of antimony mainly due to genomic alterations at the level of the subtelomeric region of chromosome 31 harboring the gene coding for the aquaglyceroporin 1 (LgAQP1). Resistance involved the loss of LgAQP1 through subtelomeric deletions in three mutants. Interestingly, the fourth mutant harbored a single G133D point mutation in LgAQP1 whose role in resistance was functionality confirmed through drug sensitivity and antimony accumulation assays. In contrast to the Leishmania subspecies that resort to extrachromosomal amplification, the Viannia strains studied here used intrachromosomal amplification and locus deletion. Conclusions/Significance This is the first report of a naturally occurred point mutation in AQP1 in antimony resistant parasites. PMID:25679388

  10. Intrachromosomal amplification, locus deletion and point mutation in the aquaglyceroporin AQP1 gene in antimony resistant Leishmania (Viannia) guyanensis.

    PubMed

    Monte-Neto, Rubens; Laffitte, Marie-Claude N; Leprohon, Philippe; Reis, Priscila; Frézard, Frédéric; Ouellette, Marc

    2015-02-01

    Antimony resistance complicates the treatment of infections caused by the parasite Leishmania. Using next generation sequencing, we sequenced the genome of four independent Leishmania guyanensis antimony-resistant (SbR) mutants and found different chromosomal alterations including aneuploidy, intrachromosomal gene amplification and gene deletion. A segment covering 30 genes on chromosome 19 was amplified intrachromosomally in three of the four mutants. The gene coding for the multidrug resistance associated protein A involved in antimony resistance was also amplified in the four mutants, most likely through chromosomal translocation. All mutants also displayed a reduced accumulation of antimony mainly due to genomic alterations at the level of the subtelomeric region of chromosome 31 harboring the gene coding for the aquaglyceroporin 1 (LgAQP1). Resistance involved the loss of LgAQP1 through subtelomeric deletions in three mutants. Interestingly, the fourth mutant harbored a single G133D point mutation in LgAQP1 whose role in resistance was functionality confirmed through drug sensitivity and antimony accumulation assays. In contrast to the Leishmania subspecies that resort to extrachromosomal amplification, the Viannia strains studied here used intrachromosomal amplification and locus deletion. This is the first report of a naturally occurred point mutation in AQP1 in antimony resistant parasites.

  11. The Role of Aquaporin and Tight Junction Proteins in the Regulation of Water Movement in Larval Zebrafish (Danio rerio)

    PubMed Central

    Kwong, Raymond W. M.; Kumai, Yusuke; Perry, Steve F.

    2013-01-01

    Teleost fish living in freshwater are challenged by passive water influx; however the molecular mechanisms regulating water influx in fish are not well understood. The potential involvement of aquaporins (AQP) and epithelial tight junction proteins in the regulation of transcellular and paracellular water movement was investigated in larval zebrafish (Danio rerio). We observed that the half-time for saturation of water influx (Ku) was 4.3±0.9 min, and reached equilibrium at approximately 30 min. These findings suggest a high turnover rate of water between the fish and the environment. Water influx was reduced by the putative AQP inhibitor phloretin (100 or 500 μM). Immunohistochemistry and confocal microscopy revealed that AQP1a1 protein was expressed in cells on the yolk sac epithelium. A substantial number of these AQP1a1-positive cells were identified as ionocytes, either H+-ATPase-rich cells or Na+/K+-ATPase-rich cells. AQP1a1 appeared to be expressed predominantly on the basolateral membranes of ionocytes, suggesting its potential involvement in regulating ionocyte volume and/or water flux into the circulation. Additionally, translational gene knockdown of AQP1a1 protein reduced water influx by approximately 30%, further indicating a role for AQP1a1 in facilitating transcellular water uptake. On the other hand, incubation with the Ca2+-chelator EDTA or knockdown of the epithelial tight junction protein claudin-b significantly increased water influx. These findings indicate that the epithelial tight junctions normally act to restrict paracellular water influx. Together, the results of the present study provide direct in vivo evidence that water movement can occur through transcellular routes (via AQP); the paracellular routes may become significant when the paracellular permeability is increased. PMID:23967101

  12. The role of aquaporin and tight junction proteins in the regulation of water movement in larval zebrafish (Danio rerio).

    PubMed

    Kwong, Raymond W M; Kumai, Yusuke; Perry, Steve F

    2013-01-01

    Teleost fish living in freshwater are challenged by passive water influx; however the molecular mechanisms regulating water influx in fish are not well understood. The potential involvement of aquaporins (AQP) and epithelial tight junction proteins in the regulation of transcellular and paracellular water movement was investigated in larval zebrafish (Danio rerio). We observed that the half-time for saturation of water influx (K(u)) was 4.3±0.9 min, and reached equilibrium at approximately 30 min. These findings suggest a high turnover rate of water between the fish and the environment. Water influx was reduced by the putative AQP inhibitor phloretin (100 or 500 μM). Immunohistochemistry and confocal microscopy revealed that AQP1a1 protein was expressed in cells on the yolk sac epithelium. A substantial number of these AQP1a1-positive cells were identified as ionocytes, either H⁺-ATPase-rich cells or Na⁺/K⁺-ATPase-rich cells. AQP1a1 appeared to be expressed predominantly on the basolateral membranes of ionocytes, suggesting its potential involvement in regulating ionocyte volume and/or water flux into the circulation. Additionally, translational gene knockdown of AQP1a1 protein reduced water influx by approximately 30%, further indicating a role for AQP1a1 in facilitating transcellular water uptake. On the other hand, incubation with the Ca²⁺-chelator EDTA or knockdown of the epithelial tight junction protein claudin-b significantly increased water influx. These findings indicate that the epithelial tight junctions normally act to restrict paracellular water influx. Together, the results of the present study provide direct in vivo evidence that water movement can occur through transcellular routes (via AQP); the paracellular routes may become significant when the paracellular permeability is increased.

  13. Osmotic water permeabilities of human placental microvillous and basal membranes.

    PubMed

    Jansson, T; Illsley, N P

    1993-03-01

    Literature data suggest that water accumulation by the human fetus is driven by osmotic gradients of small solutes. However, the existence of such gradients has not been supported by prior measurements. Attempts to estimate the size of the gradient necessary to drive net water movement have been seriously hampered by the lack of permeability data for the syncytiotrophoblast membranes. Stopped-flow light scattering techniques were employed to measure the osmotic water permeability (Pf) of microvillous (MVM) and basal membrane (BM) vesicles isolated from human term placenta. At 37 degrees C, the Pf was determined to be 1.9 +/- 0.06 x 10(-3) cm/sec for MVM and 3.1 +/- 0.20 x 10(-3) cm/sec for BM (mean +/- SD, n = 6). At 23 degrees C, Pf was reduced to 0.7 +/- 0.04 x 10(-3) cm/sec in MVM and 1.6 +/- 0.05 x 10(-3) cm/sec in BM. These Pf values are comparable to those observed in membranes where water has been shown to permeate via a lipid diffusive mechanism. Arrhenius plots of Pf over the range 20-40 degrees C were linear, with activation energies of 13.6 +/- 0.6 kcal/mol for MVM and 12.9 +/- 1.0 kcal/mol for BM. Water permeation was not affected by mercurial sulfhydryl agents and glucose transport inhibitors. These data clearly suggest that water movement across human syncytiotrophoblast membranes occurs by a lipid diffusion pathway. As noted in several other epithelial tissues, the basal membrane has a higher water permeability than the microvillous membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Drinking and water permeability in the Pacific hagfish, Eptatretus stoutii.

    PubMed

    Glover, Chris N; Wood, Chris M; Goss, Greg G

    2017-04-11

    Hagfish are osmoconformers, maintaining an internal osmolality that matches their seawater habitats. Hagfish would, therefore, appear to have no physiological need to drink, but previous studies are equivocal regarding whether drinking in hagfish occurs. The current study addressed this knowledge gap, by examining drinking and water permeability in the Pacific hagfish, Eptatretus stoutii. One-third of analysed hagfish were shown to accumulate radiolabelled drinking rate markers (tritiated inulin and polyethylene glycol-4000) in their gut tissues; however, this was attributed to the presence of markers in the blood perfusing the digestive tract, following absorption through paracellular pathways at the gill. No accumulation of marker was observed in hagfish subjected to more dilute (75% seawater) or more concentrated (125% seawater) media. Diffusive water efflux, measured by tritiated water washout, was shown to be very high, with 50% of body water exchanged within 14 to 16 min, depending on exposure salinity. In full-strength seawater, the total exchangeable pool of water was 78% of hagfish mass. We conclude that hagfish do not drink, and their high water permeability is likely to result in rapid osmotic equilibration under circumstances where perturbations may occur.

  15. Water permeability and mechanical strength of polyunsaturated lipid bilayers.

    PubMed Central

    Olbrich, K; Rawicz, W; Needham, D; Evans, E

    2000-01-01

    Micropipette aspiration was used to test mechanical strength and water permeability of giant-fluid bilayer vesicles composed of polyunsaturated phosphatidylcholine PC lipids. Eight synthetic-diacyl PCs were chosen with 18 carbon chains and degrees of unsaturation that ranged from one double bond (C18:0/1, C18:1/0) to six double bonds per PC molecule (diC18:3). Produced by increasing pipette pressurization, membrane tensions for lysis of single vesicles at 21 degrees C ranged from approximately 9 to 10 mN/m for mono- and dimono-unsaturated PCs (18:0/1, 18:1/0, and diC18:1) but dropped abruptly to approximately 5 mN/m when one or both PC chains contained two cis-double bonds (C18:0/2 and diC18:2) and even lower approximately 3 mN/m for diC18:3. Driven by osmotic filtration following transfer of individual vesicles to a hypertonic environment, the apparent coefficient for water permeability at 21 degrees C varied modestly in a range from approximately 30 to 40 microm/s for mono- and dimono-unsaturated PCs. However, with two or more cis-double bonds in a chain, the apparent permeability rose to approximately 50 microm/s for C18:0/2, then strikingly to approximately 90 microm/s for diC18:2 and approximately 150 microm/s for diC18:3. The measurements of water permeability were found to scale exponentially with the reduced temperatures reported for these lipids in the literature. The correlation supports the concept that increase in free volume acquired in thermal expansion above the main gel-liquid crystal transition of a bilayer is a major factor in water transport. Taken together, the prominent changes in lysis tension and water permeability indicate that major changes occur in chain packing and cohesive interactions when two or more cis-double bonds alternate with saturated bonds along a chain. PMID:10866958

  16. Effect of water on hydrogen permeability. [Stirling engines

    NASA Technical Reports Server (NTRS)

    Hulligan, D. D.; Tomazic, W. A.

    1984-01-01

    Doping of hydrogen with CO or CO2 was developed to reduce hydrogen permeation in Stirling engines by forming low permeability oxide coatings in the heater tubes. An end product of this process is water - which can condense in the cold parts of the engine system. If the water vapor is reduced to a low enough level, the hydrogen can reduce the oxide coating resulting in increased permeability. The equilibrium level of water (oxygen bearing gas) required to avoid reduction of the oxide coating was investigated. Results at 720 C and 13.8 MPa have shown that: (1) pure hydrogen will reduce the coating; (2) 500 ppm CO (500 ppm water equivalent) does not prevent the reduction; and (3) 500 ppm CO2 (1000 ppm water) appears to be close to the equilibrium level. Further tests are planned to define the equilibrium level more precisely and to extend the data to 820 C and 3.4, 6.9, and 13.8 MPa.

  17. Osmotic Water Permeability of Isolated Protoplasts. Modifications during Development1

    PubMed Central

    Ramahaleo, Tiana; Morillon, Raphaël; Alexandre, Joël; Lassalles, Jean-Paul

    1999-01-01

    A transference chamber was developed to measure the osmotic water permeability coefficient (Pos) in protoplasts 40 to 120 μm in diameter. The protoplast was held by a micropipette and submitted to a steep osmotic gradient created in the transference chamber. Pos was derived from the changes in protoplast dimensions, as measured using a light microscope. Permeabilities were in the range 1 to 1000 μm s−1 for the various types of protoplasts tested. The precision for Pos was ≤40%, and within this limit, no asymmetry in the water fluxes was observed. Measurements on protoplasts isolated from 2- to 5-d-old roots revealed a dramatic increase in Pos during root development. A shift in Pos from 10 to 500 μm s−1 occurred within less than 48 h. This phenomenon was found in maize (Zea mays), wheat (Triticum aestivum), and rape (Brassica napus) roots. These results show that early developmental processes modify water-transport properties of the plasma membrane, and that the transference chamber is adapted to the study of water-transport mechanisms in native membranes. PMID:10069827

  18. Water Permeability of Chlorella Cell Membranes by Nuclear Magnetic Resonance

    PubMed Central

    Stout, Darryl G.; Steponkus, Peter L.; Bustard, Larry D.; Cotts, Robert M.

    1978-01-01

    Measurement by two nuclear magnetic resonance (NMR) techniques of the mean residence time τa of water molecules inside Chlorella vulgaris (Beijerinck) var. “viridis” (Chodot) is reported. The first is the Conlon and Outhred (1972 Biochim Biophys Acta 288: 354-361) technique in which extracellular water is doped with paramagnetic Mn2+ ions. Some complications in application of this technique are identified as being caused by the affinity of Chlorella cell walls for Mn2+ ions which shortens the NMR relaxation times of intra- and extracellular water. The second is based upon observations of effects of diffusion on the spin echo of intra- and extracellular water. Echo attenuation of intracellular water is distinguished from that of extracellular water by the extent to which diffusive motion is restricted. Intracellular water, being restricted to the cell volume, suffers less echo attenuation. From the dependence of echo amplitude upon gradient strength at several values of echo time, the mean residence time of intracellular water can be determined. From the mean residence time of intracellular water, the diffusional water permeability coefficient of the Chlorella membrane is calculated to be 2.1 ± 0.4 × 10−3 cm sec−1. PMID:16660456

  19. Optimizing water permeability through the hourglass shape of aquaporins

    PubMed Central

    Gravelle, Simon; Joly, Laurent; Detcheverry, François; Ybert, Christophe; Cottin-Bizonne, Cécile; Bocquet, Lydéric

    2013-01-01

    The ubiquitous aquaporin channels are able to conduct water across cell membranes, combining the seemingly antagonist functions of a very high selectivity with a remarkable permeability. Whereas molecular details are obvious keys to perform these tasks, the overall efficiency of transport in such nanopores is also strongly limited by viscous dissipation arising at the connection between the nanoconstriction and the nearby bulk reservoirs. In this contribution, we focus on these so-called entrance effects and specifically examine whether the characteristic hourglass shape of aquaporins may arise from a geometrical optimum for such hydrodynamic dissipation. Using a combination of finite-element calculations and analytical modeling, we show that conical entrances with suitable opening angle can indeed provide a large increase of the overall channel permeability. Moreover, the optimal opening angles that maximize the permeability are found to compare well with the angles measured in a large variety of aquaporins. This suggests that the hourglass shape of aquaporins could be the result of a natural selection process toward optimal hydrodynamic transport. Finally, in a biomimetic perspective, these results provide guidelines to design artificial nanopores with optimal performances. PMID:24067650

  20. Permeability recovery of damaged water sensitive core using ultrasonic waves.

    PubMed

    Khan, Nasir; Pu, Chunsheng; Li, Xu; He, Yanlong; Zhang, Lei; Jing, Cheng

    2017-09-01

    It is imperative to recover the well productivity lose due to formation damage nearby wellbore during variant well operations. Some indispensable issues in conventional techniques make ultrasonic technology more attractive due to simple, reliable, favorable, cost-effective, and environment friendly nature. This study proposes the independent and combined use of ultrasonic waves and chemical agents for the treatment of already damaged core samples caused by exposure to distilled water. Results elucidate that ultrasonic waves with optimum (20kHz, 1000W) instead of maximum frequency and power worked well in the recovery owing to peristaltic transport caused by matching of natural frequency with acoustic waves frequency. In addition, hundred minutes was investigated as optimum irradiation time which provided ample time span to detach fine loosely suspended particles. However, further irradiation adversely affected the damaged permeability recovery. Moreover, permeability improvement attributes to cavitation due to ultrasonic waves propagation through fluid contained in porous medium and thermal energy generated by three different ways. Eventually, experimental outcomes indicated that maximum (25.3%) damaged permeability recovery was witnessed by applying ultrasonic waves with transducer #2 (20kHz and 1000W) and optimum irradiation timeframe (100min). This recovery was further increased to 45.8% by applying chemical agent and optimum ultrasonic waves simultaneously. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Water and nonelectrolyte permeability of isolated rat hepatocytes

    SciTech Connect

    Alpini, G.; Garrick, R.A.; Jones, M.J.; Nunes, R.; Tavoloni, N.

    1986-12-01

    We have measured the diffusive permeability coefficients of isolated rat hepatocytes to /sup 3/H/sub 2/O, (/sup 14/C)urea, (/sup 14/C)erythritol, (/sup 14/C)mannitol, (/sup 3/H)sucrose, and (/sup 3/H)inulin, employing a technique previously developed for erythrocytes (Redwood et al., J. Gen. Physiol 64:706-729, 1974). Diffusion coefficients for the tracer molecules were measured in packed hepatocytes, supernatant fluid, and intracellular medium (lysed hepatocytes) and were calculated assuming one-dimensional semi-infinite diffusion through a homogeneous medium. By applying the series-parallel pathway model, the following permeability coefficients (10(-5) cm/sec) for the hepatocyte plasma membrane were obtained. /sup 3/H/sub 2/O, 98.6 +/- 18.4; (/sup 14/C)urea, 18.2 +/- 5.3; (/sup 14/C)erythritol, 4.8 +/- 1.6; (/sup 14/C)mannitol, 3.1 +/- 1.4; (/sup 3/H)sucrose, 0; (/sup 3/H)inulin, 0. These results indicate that isolated rat hepatocytes are highly permeable to water and polar nonelectrolytes, when compared with other transporting epithelia. This relatively high cellular permeability is consistent with a model in which nonelectrolyte permeation is via an aqueous pathway of equivalent pore diameter of 8-12 A. The finding that (/sup 14/C)erythritol and (/sup 14/C)mannitol cross the hepatocyte plasma membrane indicates that these molecules enter the bile canaliculus through the transcellular route. Conversely, the failure of (/sup 3/H)sucrose and (/sup 3/H)inulin to permeate the hepatocyte in the isolated condition supports the concept that biliary entry of these large carbohydrates, at least that fraction which cannot be accounted for by a vesicular mechanism, must occur via the transjunctional shunt pathway.

  2. Ultrasound-assisted non-viral gene transfer of AQP1 to the irradiated minipig parotid gland restores fluid secretion

    PubMed Central

    Wang, Z; Zourelias, L; Wu, C; Edwards, PC; Trombetta, M; Passineau, MJ

    2015-01-01

    Rationale Xerostomia is a common side effect of ionizing radiation used to treat head and neck cancer. A groundbreaking Phase I human clinical trial utilizing Adenoviral gene transfer of Aquaporin-1 (AQP1) to a single salivary gland of individuals suffering from radiation-induced xerostomia has recently been reported. Unfortunately, the limitations of the Adenoviral vector system utilized in this pioneering trial preclude its advancement to a Phase II trial and we have thus undertaken to evaluate the therapeutic potential of ultrasound-assisted non-viral gene transfer (UAGT) as an alternative means of delivering AQP1 gene therapy to the salivary gland by comparing head-to-head with the canonical Adenoviral vector in a swine model. Findings Swine irradiated unilaterally with a 10Gy electron beam targeted at the parotid gland suffered from significant, sustained hyposalivation that was bilateral, despite irradiation being confined to the targeted gland. Unilateral AQP1 gene therapy with UAGT resulted in bilateral restoration of stimulated salivary flow at 48 hours and one week post-treatment (1.62+/−0.48ml, 1.87+/−0.45ml) to pre-injury levels (1.34+/−0.14ml) in a manner comparable to Adenoviral delivery (2.32+/−0.6ml, 1.33+/−0.97ml). Conclusions UAGT can replace the Adenoviral vector as a means of delivering AQP1 gene therapy in the irradiated swine model and is a candidate for advancement to a Phase I human clinical trial. PMID:25871828

  3. Effects of phase transformation of steam-water relative permeabilities

    SciTech Connect

    Verma, A.K.

    1986-03-01

    A combined theoretical and experimental study of steam-water relative permeabilities (RPs) was carried out. First, an experimental study of two-phase concurrent flow of steam and water was conducted and a set of RP curves was obtained. These curves were compared with semi-empirical and experimental results obtained by other investigators for two-phase, two-component flow (oil/gas; gas/water; gas/oil). It was found that while the wetting phase RPs were in good agreement, RPs for the steam phase were considerably higher than the non-wetting phase RPs in two-component systems. This enhancement of steam RP is attributed to phase transformation effects at the pore level in flow channels. The effects of phase transformation were studied theoretically. This study indicates that there are two separate mechanisms by which phase transformation affects RP curves: (1) Phase transformation is converging-diverging flow channels can cause an enhancement of steam phase RP. In a channel dominated by steam a fraction of the flowing steam condenses upstream from the constriction, depositing its latent heat of condensation. This heat is conducted through the solid grains around the pore throat, and evaporation takes place downstream from it. Therefore, for a given bulk flow quality; a smaller fraction of steam actually flows through the throat segments. This pore-level effect manifests itself as relative permeability enhancement on a macroscopic level; and (2) phase transformation along the interface of a stagnant phase and the phase flowing around it controls the irreducible phase saturation. Therefore, the irreducible phase saturation in steam-water flow will depend, among other factors, on the boundary conditions of the flow.

  4. Role of Pore-Lining Residues in Defining the Rate of Water Conduction by Aquaporin-0.

    PubMed

    Saboe, Patrick O; Rapisarda, Chiara; Kaptan, Shreyas; Hsiao, Yu-Shan; Summers, Samantha R; De Zorzi, Rita; Dukovski, Danijela; Yu, Jiaheng; de Groot, Bert L; Kumar, Manish; Walz, Thomas

    2017-03-14

    Compared to other aquaporins (AQPs), lens-specific AQP0 is a poor water channel, and its permeability was reported to be pH-dependent. To date, most water conduction studies on AQP0 were performed on protein expressed in Xenopus oocytes, and the results may therefore also reflect effects introduced by the oocytes themselves. Experiments with purified AQP0 reconstituted into liposomes are challenging because the water permeability of AQP0 is only slightly higher than that of pure lipid bilayers. By reconstituting high amounts of AQP0 and using high concentrations of cholesterol to reduce the permeability of the lipid bilayer, we improved the signal-to-noise ratio of water permeability measurements on AQP0 proteoliposomes. Our measurements show that mutation of two pore-lining tyrosine residues, Tyr-23 and Tyr-149 in sheep AQP0, to the corresponding residues in the high-permeability water channel AQP1 have additive effects and together increase the water permeability of AQP0 40-fold to a level comparable to that of AQP1. Molecular dynamics simulations qualitatively support these experimental findings and suggest that mutation of Tyr-23 changes the pore profile at the gate formed by residue Arg-187.

  5. Skin lipid structure controls water permeability in snake molts.

    PubMed

    Torri, Cristian; Mangoni, Alfonso; Teta, Roberta; Fattorusso, Ernesto; Alibardi, Lorenzo; Fermani, Simona; Bonacini, Irene; Gazzano, Massimo; Burghammer, Manfred; Fabbri, Daniele; Falini, Giuseppe

    2014-01-01

    The role of lipids in controlling water exchange is fundamentally a matter of molecular organization. In the present study we have observed that in snake molt the water permeability drastically varies among species living in different climates and habitats. The analysis of molts from four snake species: tiger snake, Notechis scutatus, gabon viper, Bitis gabonica, rattle snake, Crotalus atrox, and grass snake, Natrix natrix, revealed correlations between the molecular composition and the structural organization of the lipid-rich mesos layer with control in water exchange as a function of temperature. It was discovered, merging data from micro-diffraction and micro-spectroscopy with those from thermal, NMR and chromatographic analyses, that this control is generated from a sophisticated structural organization that changes size and phase distribution of crystalline domains of specific lipid molecules as a function of temperature. Thus, the results of this research on four snake species suggest that in snake skins different structured lipid layers have evolved and adapted to different climates. Moreover, these lipid structures can protect, "safety", the snakes from water lost even at temperatures higher than those of their usual habitat.

  6. Water Vapor Permeability of the Advanced Crew Escape Suit

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Kuzneth, Larry; Gillis, David; Jones, Jeffery; Daniel, Brian; Gernhardt, Michael; Hamilton, Douglas

    2009-01-01

    Crew Exploration Vehicle (CEV) crewmembers are expected to return to earth wearing a suit similar to the current Advanced Crew Escape Suit (ACES). To ensure optimum cognitive performance, suited crewmembers must maintain their core body temperature within acceptable limits. There are currently several options for thermal maintenance in the post-landing phase. These include the current baseline, which uses an ammonia boiler, purge flow using oxygen in the suit, accessing sea water for liquid cooling garment (LCG) cooling and/or relying on the evaporative cooling capacity of the suit. These options vary significantly in mass, power, engineering and safety factors, with relying on the evaporative cooling capacity of the suit being the least difficult to implement. Data from previous studies indicates that the evaporative cooling capacity of the ACES was much higher than previously expected, but subsequent tests were performed for longer duration and higher metabolic rates to better define the water vapor permeability of the ACES. In these tests five subjects completed a series of tests performing low to moderate level exercise in order to control for a target metabolic rate while wearing the ACES in an environmentally controlled thermal chamber. Four different metabolic profiles at a constant temperature of 95 F and relative humidity of 50% were evaluated. These tests showed subjects were able to reject about twice as much heat in the permeable ACES as they were in an impermeable suit that had less thermal insulation. All of the heat rejection differential is attributed to the increased evaporation capability through the Gortex bladder of the suit.

  7. Water Vapor Permeability of the Advanced Crew Escape Suit

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Kuzneth, Larry; Gillis, David; Jones, Jeffery; Daniel, Brian; Gernhardt, Michael; Hamilton, Douglas

    2009-01-01

    Crew Exploration Vehicle (CEV) crewmembers are expected to return to earth wearing a suit similar to the current Advanced Crew Escape Suit (ACES). To ensure optimum cognitive performance, suited crewmembers must maintain their core body temperature within acceptable limits. There are currently several options for thermal maintenance in the post-landing phase. These include the current baseline, which uses an ammonia boiler, purge flow using oxygen in the suit, accessing sea water for liquid cooling garment (LCG) cooling and/or relying on the evaporative cooling capacity of the suit. These options vary significantly in mass, power, engineering and safety factors, with relying on the evaporative cooling capacity of the suit being the least difficult to implement. Data from previous studies indicates that the evaporative cooling capacity of the ACES was much higher than previously expected, but subsequent tests were performed for longer duration and higher metabolic rates to better define the water vapor permeability of the ACES. In these tests five subjects completed a series of tests performing low to moderate level exercise in order to control for a target metabolic rate while wearing the ACES in an environmentally controlled thermal chamber. Four different metabolic profiles at a constant temperature of 95 F and relative humidity of 50% were evaluated. These tests showed subjects were able to reject about twice as much heat in the permeable ACES as they were in an impermeable suit that had less thermal insulation. All of the heat rejection differential is attributed to the increased evaporation capability through the Gortex bladder of the suit.

  8. Human platelet diffusional water permeability measured by nuclear magnetic resonance.

    PubMed

    Wong, K R; Verkman, A S

    1987-06-01

    To examine whether water transport in human platelets is mediated by an aqueous pore or channel, the ratio of osmotic to diffusional water permeability coefficients (Pf/Pd) was measured. Pd was measured from protein spin-lattice relaxation times in a dense platelet suspension (approximately 20% intracellular exchangeable water) using 20 mM solution Mn as a paramagnetic quencher. The decay of magnetization was biexponential with time constants of 1.3 and 6.9 ms (10 MHz, 37 degrees C), corresponding to a Pd of (2.9 +/- 0.2) X 10(-3) cm/s (SE; n = 8). Pd did not depend on concentrations of Mn (6-20 mM) or of platelets (2-4 X 10(10) platelets/ml), but increased to 4.5 X 10(-3) cm/s with addition of gramicidin (6 micrograms/10(10) platelets). 54Mn uptake studies showed less than 1% of equilibrium uptake of Mn into platelets in 30 min at 37 degrees C. The activation energies (Ea) for Pd were 4.5 kcal/mol (less than 28 degrees C) and 16.3 kcal/mol (greater than 28 degrees C). Pf was measured by a stopped-flow light scattering technique as reported previously [M. M. Meyer and A. S. Verkman, Human platelet osmotic water and nonelectrolyte transport, Am. J. Physiol. 251 (Cell Physiol. 20): C549-C557, 1986], in which the time course of platelet volume was measured in response to a 100 mM inwardly directed sucrose gradient. At 37 degrees C, Pf was (2.7 +/- 0.2) X 10(-3) cm/s and independent of [Mn]. The measured platelet Pf/Pd of 0.93 +/- 0.1 suggests that unlike water transport in erythrocytes, platelet water transport is not associated with an aqueous channel.

  9. A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells.

    PubMed

    Shu, Zhiquan; Hughes, Sean M; Fang, Cifeng; Huang, Jinghua; Fu, Baiwen; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-04-01

    Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3(+) T cells and CD14(+) macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10(-3) cm/min), but transport of the fourth CPA, glycerol, occurred 50-150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells. Published by Elsevier Inc.

  10. A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells

    PubMed Central

    Shu, Zhiquan; Hughes, Sean M.; Fang, Cifeng; Huang, Jinghua; Fu, Baiwen; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-01-01

    Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3+ T cells and CD14+ macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10−3 cm/min), but transport of the fourth CPA, glycerol, occurred 50–150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells. PMID:26976225

  11. Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water

    DOE R&D Accomplishments Database

    Poston, S. W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  12. Oil recovery enhancement from fractured, low permeability reservoirs. [Carbonated Water

    SciTech Connect

    Poston, S.W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods.Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks.Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  13. Hepatocyte membrane water permeability measured by silicone layer filtering centrifugation.

    PubMed

    Gradilone, Sergio A; Ochoa, J Elena; García, Fabiana; Larocca, M Cecilia; Pellegrino, José M; Marinelli, Raúl A

    2002-03-01

    We previously found that hepatocytes are able to control their osmotic membrane water permeability (P(f)) by regulating the number of surface aquaporin water channels. Hepatocyte P(f) has been assessed by phase-contrast microscopy and cell image analysis, an established but relatively laborious procedure. We report here an alternative method to assess hepatocyte P(f) based on a single silicone layer filtering centrifugation system. Isolated rat hepatocytes were incubated in hypotonic or isotonic buffers containing (3)H(2)O as a tracer and, then, were filtered by rapid centrifugation through a silicone layer down to a lysis layer. Osmotically driven radioactivity (i.e., (3)H(2)O) within hepatocytes was calculated as the difference between the dpm in lysis media measured under hypotonic and isotonic conditions. The P(f) calculated from the initial slope of the radioactivity-versus-time curve was 18 microm/s at 4 degrees C. Hepatocytes treated with dibutyryl cyclic AMP, to increase P(f) through the plasma membrane insertion of aquaporins, showed an increased P(f) value of 37 microm/s. The aquaporin blocker dimethyl sulfoxide selectively prevented the agonist-induced hepatocyte P(f). These data are in good agreement with the corresponding values determined by quantitative phase-contrast microscopy; thus, the method developed allows the rapid and reliable measurement of hepatocyte P(f).

  14. Simulating gas-water relative permeabilities for nanoscale porous media with interfacial effects

    NASA Astrophysics Data System (ADS)

    Wang, Jiulong; Song, Hongqing; Li, Tianxin; Wang, Yuhe; Gao, Xuhua

    2017-08-01

    This paper presents a theoretical method to simulate gas-water relative permeability for nanoscale porous media utilizing fractal theory. The comparison between the calculation results and experimental data was performed to validate the present model. The result shows that the gas-water relative permeability would be underestimated significantly without interfacial effects. The thinner the liquid film thickness, the greater the liquid-phase relative permeability. In addition, both liquid surface diffusion and gas diffusion coefficient can promote gas-liquid two-phase flow. Increase of liquid surface diffusion prefer to increase liquid-phase permeability obviously as similar as increase of gas diffusion coefficient to increase gas-phase permeability. Moreover, the pore structure will become complicated with the increase of fractal dimension, which would reduce the gas-water relative permeability. This study has provided new insights for development of gas reservoirs with nanoscale pores such as shale.

  15. Serpentinization: Getting water into a low permeability peridotite

    NASA Astrophysics Data System (ADS)

    Ulven, Ole Ivar

    2017-04-01

    Fluid consuming rock transformation processes occur in a variety of settings in the Earth's crust. One such process is serpentinization, which involves hydration of ultramafic rock to form serpentine. With peridotite being one of the dominating rocks in the oceanic crust, this process changes physical and chemical properties of the crust at a large scale, increases the amount of water that enters subduction zones, and might even affect plate tectonics te{jamtveit}. A significant number of papers have studied serpentinization in different settings, from reaction fronts progressing over hundreds of meters te{rudge} to the interface scale fracture initiation te{pluemper}. However, the process represents a complicated multi-physics problem which couples external stress, mechanical deformation, volume change, fracture formation, fluid transport, the chemical reaction, heat production and heat flow. Even though it has been argued that fracture formation caused by the volume expansion allows fluid infiltration into the peridotite te{rudge}, it remains unclear how sufficient water can enter the initially low permeability peridotite to pervasively serpentinize the rock at kilometre scale. In this work, we study serpentinization numerically utilizing a thermo-hydro-mechanical model extended with a fluid consuming chemical reaction that increases the rock volume, reduces its density and strength, changes the permeability of the rock, and potentially induces fracture formation. The two-way coupled hydromechanical model is based on a discrete element model (DEM) previously used to study a volume expanding process te{ulven_1,ulven_2} combined with a fluid transport model based on poroelasticity te{ulven_sun}, which is here extended to include fluid unsaturated conditions. Finally, a new model for reactive heat production and heat flow is introduced, to make this probably the first ever fully coupled chemo-thermo-hydromechanical model describing serpentinization. With this model

  16. Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras

    PubMed Central

    Baumgart, Florian; Rossi, Andrea

    2012-01-01

    Aquaporins (AQPs) have a broad range of cellular and organ functions; however, nontoxic inhibitors of AQP water transport are not available. Here, we applied chromophore-assisted light inactivation (CALI) to inhibit the water permeability of AQP1, and of two AQP4 isoforms (M1 and M23), one of which (M23) forms aggregates at the cell plasma membrane. Chimeras containing Killer Red (KR) and AQPs were generated with linkers of different lengths. Osmotic water permeability of cells expressing KR/AQP chimeras was measured from osmotic swelling–induced dilution of cytoplasmic chloride, which was detected using a genetically encoded chloride-sensing fluorescent protein. KR-AQP1 red fluorescence was bleached rapidly (∼10% per second) by wide-field epifluorescence microscopy. After KR bleaching, KR-AQP1 water permeability was reduced by up to 80% for the chimera with the shortest linker. Remarkably, CALI-induced reduction in AQP4-KR water permeability was approximately twice as efficient for the aggregate-forming M23 isoform; this suggests intermolecular CALI, which was confirmed by native gel electrophoresis on cells coexpressing M23-AQP4-KR and myc-tagged M23-AQP4. CALI also disrupted the interaction of AQP4 with a neuromyelitis optica autoantibody directed against an extracellular epitope on AQP4. CALI thus permits rapid, spatially targeted and irreversible reduction in AQP water permeability and interactions in live cells. Our data also support the utility of CALI to study protein–protein interactions as well as other membrane transporters and receptors. PMID:22200949

  17. The effect of air permeability and water vapor permeability of cleanroom clothing on physiological responses and wear comfort.

    PubMed

    Chen, Te-Hung; Chen, Wan-Ping; Wang, Mao-Jiun J

    2014-01-01

    The function of cleanroom clothing is to protect the product from contamination by people, and to dissipate electrostatic discharge. People in the cleanroom work environment often complain about the discomforts associated with the wearing of cleanroom clothing. The purpose of this study is to investigate the effect of air permeability and water vapor permeability of cleanroom clothing on the subject's physiological and subjective responses. Five male and five female subjects participated in this study. The experimental goal was to simulate the operator's regular tasks in a semiconductor manufacturing cleanroom. Each subject completed three treatment combinations with three different cleanroom clothing types. A three-factor experiment was designed (significance level p = 0.05). The independent variables included gender, cleanroom clothing, and duration. The dependent measures included heart rate, core temperature, skin temperature, micro-climate relative humidity, micro-climate temperature, and subjective responses. A total of 40 min was involved for each treatment condition. The results indicate that skin temperature, micro-climate temperature and micro-climate relative humidity were lower while wearing cleanroom clothing with high air permeability and high water vapor permeability. The significant gender difference was found in skin temperature. As the task time increased, the micro-climate temperature also increased but the micro-climate relative humidity decreased at first and then increased. In addition, the physiological responses showed significant positive correlations with the subjective perception of clothing comfort. The findings of this study may provide useful information for cleanroom clothing design and selection.

  18. Osmotic water permeability of plasma and vacuolar membranes in protoplasts I: high osmotic water permeability in radish (Raphanus sativus) root cells as measured by a new method.

    PubMed

    Murai-Hatano, Mari; Kuwagata, Tsuneo

    2007-03-01

    Intra- and transcellular water movements in plants are regulated by the water permeability of the plasma membrane (PM) and vacuolar membrane (VM) in plant cells. In the present study, we investigated the osmotic water permeability of both PM (P ( f1)) and VM (P ( f2)), as well as the bulk osmotic water permeability of a protoplast (P ( f(bulk))) isolated from radish (Raphanus sativus) roots. The values of P ( f(bulk)) and P ( f2) were determined from the swelling/shrinking rate of protoplasts and isolated vacuoles under hypo- or hypertonic conditions. In order to minimize the effect of unstirred layer, we monitored dropping or rising protoplasts (vacuoles) in sorbitol solutions as they swelled or shrunk. P ( f1) was calculated from P ( f(bulk)) and P ( f2) by using the 'three-compartment model', which describes the theoretical relationship between P ( f1), P ( f2) and P ( f(bulk)) (Kuwagata and Murai-Hatano in J Plant Res, 2007). The time-dependent changes in the volume of protoplasts and isolated vacuoles fitted well to the theoretical curves, and solute permeation of PM and VM was able to be neglected for measuring the osmotic water permeability. High osmotic water permeability of more than 500 mum s(-1), indicating high activity of aquaporins (water channels), was observed in both PM and VM in radish root cells. This method has the advantage that P ( f1) and P ( f2) can be measured accurately in individual higher plant cells.

  19. Recovery of municipal waste incineration bottom ash and water treatment sludge to water permeable pavement materials.

    PubMed

    Lin, Cheng-Fang; Wu, Chung-Hsin; Ho, Hsiu-Mai

    2006-01-01

    Water treatment plant sludge and municipal solid waste incinerator bottom ash are non-hazardous residues, and they can be reprocessed to produce useful materials for city public works. In this study, an effort was endeavored to investigate the properties of water permeable bricks made of water treatment sludge and bottom ash without involving an artificial aggregate step. The water treatment plant sludge was dried and ground, and the bottom ash was subjected to magnetic separation to remove ferrous metals. Both sludge and bottom ash were ground and sieved to a size of <2mm. Different contents of water treatment sludge (70-95% by weight) were mixed with bottom ash and the blocks were molded under a pressure of 110 kg/cm2. Thereafter, the molded blocks were sintered at temperatures of 900-1200 degrees C for 60-360 min. The compressive strength, permeability and water absorption rate of the sintered brick were examined and compared to relevant standards. The amount of bottom ash added in the mixture with water treatment sludge affects both the compressive strength and the permeability of the sintered bricks. The two effects are antonymous as higher bottom ash content will develop a beehive configuration and have more voids in the brick. It is concluded that a 20% weight content of bottom ash under a sintering condition of 1150 degrees C for 360 min can generate a brick with a compressive strength of 256 kg/cm2, a water absorption ratio of 2.78% and a permeability of 0.016 cm/s.

  20. Influence of Decenylsuccinic Acid on Water Permeability of Plant Cells 1

    PubMed Central

    Lee, O. Y.; Stadelmann, Ed. J.; Weiser, C. J.

    1972-01-01

    Decenylsuccinic acid altered permeability to water of epidermal cells of bulb scales of Allium cepa and of the leaf midrib of Rhoeo discolor. Water permeability, as determined by deplasmolysis time measurements, was related to the dose of undissociated decenylsuccinic acid (mm undissociated decenylsuccinic acid × minute). No relationship was found between permeability and total dose of decenylsuccinic acid, or dose of dissociated decenylsuccinic acid, suggesting that the undissociated molecule was the active factor in permeability changes and injury. At doses which did not damage cells (0.0008 to 0.6 [mm of the undissociated molecule × minute]) decenylsuccinic acid decreased water permeability. At higher doses (e.g., 4 to 8 [mm × minute]) injury to cells was common and decenylsuccinic acid increased permeability. Doses above the 10 to 20 (mm × minute) range were generally lethal. The plasmolysis form of uninjured cells was altered and protoplasmic swelling occasionally was observed. The dose-dependent reversal of water permeability changes (decreased to increased permeability) may reflect decenylsuccinic acid-induced changes in membrane structure. Reported effects of decenylsuccinic acid on temperature dependence of permeability and frost resistance were not verified. Images PMID:16658227

  1. Conversion of aquaporin 6 from an anion channel to a water-selective channel by a single amino acid substitution

    PubMed Central

    Liu, Kun; Kozono, David; Kato, Yasuhiro; Agre, Peter; Hazama, Akihiro; Yasui, Masato

    2005-01-01

    Aquaporin (AQP) 6 belongs to the aquaporin water channel family. Unlike other aquaporins, AQP6 functions not as a water channel but as an anion-selective channel. Single-channel analyses have shown AQP6 to flicker rapidly between closed and open status. The atomic structure of AQP1 and amino acid sequence alignments of the mammalian aquaporins reveal two well conserved glycine residues: Gly-57 in transmembrane helix (TM) 2 and Gly-173 in TM5 reside at the contact point where the two helices cross in human AQP1. Uniquely, all known mammalian orthologs of AQP6 have an asparagine residue (Asn-60) at the position corresponding to Gly-57. Here we show that a single residue substitution (N60G in rat AQP6) totally eliminates the anion permeability of AQP6 when expressed in Xenopus oocytes, but the N60G oocytes exhibit significantly higher osmotic water permeability under basal conditions. Replacement of the glycine at this site in AQP0, AQP1, and AQP2 blocked expression of the mutants at the oocyte plasma membrane. We propose that the asparagine residue at the contact point between TM2 and TM5 in AQP6 may function as a teeter board needed for rapid structural oscillations during anion permeation. PMID:15671159

  2. Conversion of aquaporin 6 from an anion channel to a water-selective channel by a single amino acid substitution.

    PubMed

    Liu, Kun; Kozono, David; Kato, Yasuhiro; Agre, Peter; Hazama, Akihiro; Yasui, Masato

    2005-02-08

    Aquaporin (AQP) 6 belongs to the aquaporin water channel family. Unlike other aquaporins, AQP6 functions not as a water channel but as an anion-selective channel. Single-channel analyses have shown AQP6 to flicker rapidly between closed and open status. The atomic structure of AQP1 and amino acid sequence alignments of the mammalian aquaporins reveal two well conserved glycine residues: Gly-57 in transmembrane helix (TM) 2 and Gly-173 in TM5 reside at the contact point where the two helices cross in human AQP1. Uniquely, all known mammalian orthologs of AQP6 have an asparagine residue (Asn-60) at the position corresponding to Gly-57. Here we show that a single residue substitution (N60G in rat AQP6) totally eliminates the anion permeability of AQP6 when expressed in Xenopus oocytes, but the N60G oocytes exhibit significantly higher osmotic water permeability under basal conditions. Replacement of the glycine at this site in AQP0, AQP1, and AQP2 blocked expression of the mutants at the oocyte plasma membrane. We propose that the asparagine residue at the contact point between TM2 and TM5 in AQP6 may function as a teeter board needed for rapid structural oscillations during anion permeation.

  3. Experimental investigation the effect of nanoparticles on the oil-water relative permeability

    NASA Astrophysics Data System (ADS)

    Amedi, Hamidreza; Ahmadi, Mohammad-Ali

    2016-05-01

    This paper presents the effects of the nanosilica particles on the water and oil relative permeability curves at reservoir conditions. Real reservoir crude oil sample was employed as an oil phase in relative permeability measurements. In addition, real carbonate reservoir rock samples were employed as a porous media in core displacement experiments. To determine relative permeability curves, the unsteady-state approach was employed in which Toth et al. method was applied to the recovery data points. By increasing the nanosilica content of the aqueous phase the oil relative permeability increased while the residual oil saturation decreased; however, by increasing the nanosilica concentration in the aqueous solution the water relative permeability decreased. The outcomes of this paper can provide a better understanding regarding chemically enhanced oil recovery (EOR) by nanoparticles. Moreover, relative permeability curves help us in the history matching section of reservoir simulation for any further EOR scenarios.

  4. Identification and characterisation of a functional aquaporin water channel (Anomala cuprea DRIP) in a coleopteran insect.

    PubMed

    Nagae, Tomone; Miyake, Seiji; Kosaki, Shiho; Azuma, Masaaki

    2013-07-15

    Water transport across the plasma membrane depends on the presence of the water channel aquaporin (AQP), which mediates the bulk movement of water through osmotic and pressure gradients. In terrestrial insects, which are solid and/or plant feeders, the entrance and exit of water is primarily executed along the alimentary tract, where the hindgut, particularly the rectum, is the major site of water conservation. A cDNA encoding the homologue of the water-specific Drosophila AQP [Drosophila integral protein (DRIP)] was identified through the RT-PCR of RNA isolated from the rectum of the cupreous chafer larvae, Anomala cuprea, a humus and plant root feeder. This gene (Anocu AQP1) has a predicted molecular mass of 26.471 kDa, similar to the DRIP clade of insect AQPs characterised from caterpillars, flies and several liquid-feeding insects. When expressed in Xenopus laevis oocytes, Anocu AQP1 showed the hallmarks of aquaporin-mediated water transport but no glycerol or urea permeability, and the reversible inhibition of elevated water transport through 1 mmol l(-1) HgCl2. This is the first experimental demonstration of the presence of a water-specific AQP, namely DRIP, in the Coleoptera. The genome of the model beetle Tribolium castaneum contains six putative AQP sequences, one of which (Trica-1a, XP_972862) showed the highest similarity to Anocu AQP1 (~60% amino acid identity). Anocu AQP1 is predominantly expressed in the rectum. Using a specific antibody raised against DRIP in the silkworm Bombyx mori (AQP-Bom1), Anocu AQP1 was localised to the apical plasma membrane of rectal epithelial cells, and lacking in the midgut and gastric caecal epithelia. Based on the BeetleBase prediction, there are three putative AQPs (Trica-3a, 3b, 3c: XP_970728, 970912, 970791) that are homologous to B. mori aquaglyceroporin [AQP-Bom2 (GLP)]. The immunocytochemical studies using the specific anti-peptide antibody against AQP-Bom2 revealed the presence of the GLP homologue at the apical

  5. INTRODUCTION TO PERMEABLE REACTIVE BARRIERS FOR GROUND WATER REMEDIATION

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  6. PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  7. Quercetin alters uterine fluid volume and aquaporin (AQP) subunits (AQP-1, 2, 5 & 7) expression in the uterus in the presence of sex-steroids in rats.

    PubMed

    Shahzad, Huma; Giribabu, Nelli; Karim, Kamarulzaman; Muniandy, Sekaran; Kassim, Normadiah M; Salleh, Naguib

    2017-03-22

    Effects of quercetin on uterine fluid volume and aquaporin (AQP) expression in the uterus were investigated. Estradiol (E) or estradiol followed by progesterone (E+P) were given to ovariectomised rats with or without quercetin (10, 50 or 100mg/kg/day) treatment. Uteri were harvested and its inner/outer circumference ratio was determined. AQP-1, 2, 5 and 7 mRNA and protein levels in uterus were quantified by Real-time PCR and Western blotting respectively. Protein distribution was observed by immunohistochemistry. Administration of quercetin in E-treated rats decreased the uterine fluid volume and uterine AQP-2 expression. In E+P-treated rats, administration of 100mg/kg/day quercetin increased uterine fluid volume, AQP-1 and 2 expression but decreased AQP-7 expression in uterus. AQP-1 was distributed in stromal blood vessels while AQP-2, 5 and 7 were distributed in uterine epithelium.

  8. ECONOMICS ANALYSIS OF THE IMPLEMENTATION OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    This report presents an analysis of the cost of using permeable reactive barriers to remediate contaminated ground water. When possible, these costs are compared with the cost of pump-and-treat technology for similar situations. Permeable reactive barriers are no longer perceiv...

  9. ECONOMICS ANALYSIS OF THE IMPLEMENTATION OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    This report presents an analysis of the cost of using permeable reactive barriers to remediate contaminated ground water. When possible, these costs are compared with the cost of pump-and-treat technology for similar situations. Permeable reactive barriers are no longer perceiv...

  10. Structure and Water Permeability of Fully Hydrated DiphytanoylPC

    PubMed Central

    Tristram-Nagle, Stephanie; Kim, Dong Joo; Akhunzada, Nadia; Kučerka, Norbert; Mathai, John C.; Katsaras, John; Zeidel, Mark; Nagle, John F.

    2010-01-01

    Diphytanoylphosphatidylcholine (DPhyPC) is a branched chain lipid often used for model membrane studies, including peptide/lipid interactions, ion channels and lipid rafts. This work reports results of volume measurements, water permeability measurements Pf, X-ray scattering from oriented samples, and x-ray and neutron scattering from unilamellar vesicles at T=30 °C. We measured the volume/lipid VL = 1426 ± 1 Å3. The area/lipid was found to be 80.5 ± 1.5 Å2 when both x-ray and neutron data were combined with the SDP model analysis (Kučerka et al., 2008); this is substantially larger than the area of DOPC which has the largest area of the common linear chain lipids. Pf was measured to be 7.0 ± 1.0 ×10−3 cm/sec; this is considerably smaller than predicted by the recently proposed 3-slab model (Nagle et al., 2008). This disagreement can be understood if there is a diminished diffusion coefficient in the hydrocarbon core of DPhyPC and that is supported by previous molecular dynamics simulations (Shinoda et al., 2004). While the DPhyPC head-head thickness (DHH= 36.4 Å), and Hamaker parameter (H=4.5 ×10−21J) were similar to the linear chain lipid DOPC, the bending modulus (KC=5.2 ± 0.5 ×10−21J) was 30% smaller. Our results suggest that, from the biophysical perspective, DPhyPC belongs to a different family of lipids than phosphatidylcholines that have linear chain hydrocarbon chains. PMID:20447383

  11. Estradiol, progesterone and genistein differentially regulate levels of aquaporin (AQP)-1, 2, 5 and 7 expression in the uteri of ovariectomized, sex-steroid deficient rats.

    PubMed

    Chinigarzadeh, Asma; Muniandy, Sekaran; Salleh, Naguib

    2016-11-01

    In this study, effects of estradiol, progesterone and genistein on uterine aquaporin (AQP)-1, 2, 5 and 7 expression were investigated in sex-steroid deficient state which could help to elucidate the mechanisms underlying uterine fluid volume changes that were reported under these hormone and hormone-like compound influences. Uteri from ovariectomized, female Sprague-Dawley rats receiving seven days estradiol, progesterone or genistein (25, 50 and 100mg/kg/day) were harvested and levels of AQP-1, 2, 5 and 7 proteins and mRNAs were determined by Western blotting and Real-time PCR (qPCR) respectively. Distribution of these proteins in uterus was observed by immunohistochemistry. Genistein caused a dose-dependent increase in uterine AQP-1, 2, 5 and 7 protein and mRNA expression, however at the levels lower than following estradiol or progesterone stimulations. Effects of genistein were antagonized by estradiol receptor blocker, ICI 182780. Estradiol caused the highest AQP-2 protein and mRNA expression while progesterone caused the highest AQP-1, 5 and 7 protein and mRNA expression in uterus. AQP-1, 2, 5 and 7 protein were found to be distributed in the myometrium as well as in uterine luminal and glandular epithelia and endometrial blood vessels. In conclusion, the observed effects of estradiol, progesterone and genistein on uterine AQP-1, 2, 5 and 7 expression could help to explain the differences in the amount of fluid accumulated in the uterus under these different conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. The water channel protein aquaporin 1 regulates cellular metabolism and competitive fitness in a global fungal pathogen Cryptococcus neoformans.

    PubMed

    Meyers, Gena Lee; Jung, Kwang-Woo; Bang, Soohyun; Kim, Jungyeon; Kim, Sooah; Hong, Joohyeon; Cheong, Eunji; Kim, Kyoung Heon; Bahn, Yong-Sun

    2017-03-02

    In this study, an aquaporin protein, Aqp1, in Cryptococcus neoformans, which can lead either saprobic or parasitic lifestyles and causes life-threatening fungal meningitis was identified and characterized. AQP1 expression was rapidly induced (via the HOG pathway) by osmotic or oxidative stress. In spite of such transcriptional regulation, Aqp1 was found to be largely unnecessary for adaptation to diverse environmental stressors, regardless of the presence of the polysaccharide capsule. The latter is shown here to be a key environmental-stress protectant for C. neoformans. Furthermore, Aqp1 was not required for the development and virulence of C. neoformans. Deletion of AQP1 increased hydrophobicity of the cell surface. The comparative metabolic profiling analysis of the aqp1Δ mutant and AQP1-overexpressing strains revealed that deletion of AQP1 significantly increased cellular accumulation of primary and secondary metabolites, whereas overexpression of AQP1 depleted such metabolites, suggesting that this water channel protein performs a critical function in metabolic homeostasis. In line with this result, it was found that the aqp1Δ mutant (which is enriched with diverse metabolites) survived better than the wild type and a complemented strain, indicating that Aqp1 is likely to be involved in competitive fitness of this fungal pathogen.

  13. Electrical parameters and water permeability properties of monolayers formed by T84 cells cultured on permeable supports.

    PubMed

    Ozu, M; Toriano, R; Capurro, C; Parisi, M

    2005-01-01

    T84 is an established cell line expressing an enterocyte phenotype whose permeability properties have been widely explored. Osmotic permeability (POSM), hydraulic permeability (PHYDR) and transport-associated net water fluxes (JW-transp), as well as short-circuit current (ISC), transepithelial resistance (RT), and potential difference (deltaVT) were measured in T84 monolayers with the following results: POSM 1.3 +/- 0.1 cm.s-1 x 10-3; PHYDR 0.27 +/- 0.02 cm.s-1; RT 2426 +/- 109 omega.cm2, and deltaVT 1.31 +/- 0.38 mV. The effect of 50 microM 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a "net Cl- secretory agent", on T84 cells was also studied. We confirm the reported important increase in ISC induced by DCEBIO which was associated here with a modest secretory deltaJW-transp. The present results were compared with those reported using the same experimental approach applied to established cell lines originating from intestinal and renal epithelial cells (Caco-2, LLC-PK1 and RCCD-1). No clear association between PHYDR and RT could be demonstrated and high PHYDR values were observed in an electrically tight epithelium, supporting the view that a "water leaky" barrier is not necessarily an "electrically leaky" one. Furthermore, the modest secretory deltaJW-transp was not consistent with previous results obtained with RCCD-1 cells stimulated with vasopressin (absorptive fluxes) or with T84 cells secreting water under the action of Escherichia coli heat stable enterotoxin. We conclude that, while the presence of aquaporins is necessary to dissipate an external osmotic gradient, coupling between water and ion transport cannot be explained by a simple and common underlying mechanism.

  14. Water permeability of nanoporous graphene at realistic pressures for reverse osmosis desalination

    SciTech Connect

    Cohen-Tanugi, David; Grossman, Jeffrey C.

    2014-08-21

    Nanoporous graphene (NPG) shows tremendous promise as an ultra-permeable membrane for water desalination thanks to its atomic thickness and precise sieving properties. However, a significant gap exists in the literature between the ideal conditions assumed for NPG desalination and the physical environment inherent to reverse osmosis (RO) systems. In particular, the water permeability of NPG has been calculated previously based on very high pressures (1000–2000 bars). Does NPG maintain its ultrahigh water permeability under real-world RO pressures (<100 bars)? Here, we answer this question by drawing results from molecular dynamics simulations. Our results indicate that NPG maintains its ultrahigh permeability even at low pressures, allowing a permeate water flux of 6.0 l/h-bar per pore, or equivalently 1041 ± 20 l/m{sup 2}-h-bar assuming a nanopore density of 1.7 × 10{sup 13} cm{sup −2}.

  15. Water permeability of nanoporous graphene at realistic pressures for reverse osmosis desalination

    NASA Astrophysics Data System (ADS)

    Cohen-Tanugi, David; Grossman, Jeffrey C.

    2014-08-01

    Nanoporous graphene (NPG) shows tremendous promise as an ultra-permeable membrane for water desalination thanks to its atomic thickness and precise sieving properties. However, a significant gap exists in the literature between the ideal conditions assumed for NPG desalination and the physical environment inherent to reverse osmosis (RO) systems. In particular, the water permeability of NPG has been calculated previously based on very high pressures (1000-2000 bars). Does NPG maintain its ultrahigh water permeability under real-world RO pressures (<100 bars)? Here, we answer this question by drawing results from molecular dynamics simulations. Our results indicate that NPG maintains its ultrahigh permeability even at low pressures, allowing a permeate water flux of 6.0 l/h-bar per pore, or equivalently 1041 ± 20 l/m2-h-bar assuming a nanopore density of 1.7 × 1013 cm-2.

  16. Water permeability of nanoporous graphene at realistic pressures for reverse osmosis desalination.

    PubMed

    Cohen-Tanugi, David; Grossman, Jeffrey C

    2014-08-21

    Nanoporous graphene (NPG) shows tremendous promise as an ultra-permeable membrane for water desalination thanks to its atomic thickness and precise sieving properties. However, a significant gap exists in the literature between the ideal conditions assumed for NPG desalination and the physical environment inherent to reverse osmosis (RO) systems. In particular, the water permeability of NPG has been calculated previously based on very high pressures (1000-2000 bars). Does NPG maintain its ultrahigh water permeability under real-world RO pressures (<100 bars)? Here, we answer this question by drawing results from molecular dynamics simulations. Our results indicate that NPG maintains its ultrahigh permeability even at low pressures, allowing a permeate water flux of 6.1 × 10−15 l/h bar per pore [Corrected], or equivalently 1041 ± 20 l/m(2)-h-bar assuming a nanopore density of 1.7 × 10(13) cm(-2).

  17. Predicting relative permeability from water retention: A direct approach based on fractal geometry

    NASA Astrophysics Data System (ADS)

    Cihan, Abdullah; Tyner, John S.; Perfect, Edmund

    2009-04-01

    Commonly, a soil's relative permeability curve is predicted from its measured water retention curve by fitting equations that share parameters between the two curves (e.g., Brooks/Corey-Mualem and van Genuchten-Mualem). We present a new approach to predict relative permeability by direct application of measured soil water retention data without any fitting procedures. The new relative permeability model, derived from a probabilistic fractal approach, appears in series form as a function of suction and the incremental change in water content. This discrete approach describes the drained pore space and permeability at different suctions incorporating the effects of both pore size distribution and connectivity among water-filled pores. We compared the new model performance predicting relative permeability to that of the van Genuchten-Mualem (VG-M) model for 35 paired data sets from the Unsaturated Soil hydraulic Database (UNSODA) and five other previously published data sets. At the 5% level of significance, the new method predicts relative permeabilities from the UNSODA database significantly better (mean logarithmic root-mean-square error, LRMSE = 0.813) than the VG-M model (LRMSE = 1.555). Each prediction of relative permeability from the five other previously published data sets was also significantly better.

  18. [Calciumdependent mechanisms in vasopressin regulation of osmotic water permeability in the mouse kidney collecting duct cells].

    PubMed

    Khodus, G R; Solenov, E I; Nesterov, V V; Katkova, L E; Ivanova, L N

    2006-05-01

    In the study, the role of PKC and Ca++ in vasopressin regulation of the plasma membrane water permeability was studied in the cells of the mouse kidney collecting duct. Coefficient of osmotic water permeability of total cell surface (Pf) was calculated from the initial rate of cell swelling following the osmotic shock caused by changing the medium osmolarity from isotonic to hypotonic (300 mOsm to 200 mOsm). Desmopressin (dDAVP 1 nM) increased the Pf in hydrated mice from 168.4 +/- 11.8 microm/s up to 231.3 +/- 14.7 microm/s. The Ca++ chelator BAPTA prevented the desmopressin-induced increase in water permeability. Inhibition of PKC (Ro-31-8220 0.1 microM) also abolished the desmopressin-stimulated increase of plasma membrane water permeability, whereas inhibitor of PKC alone did not suppress the stimulation of the water permeability by db-cAMP. The PKC activity and calciumdependent second messengers seem to be important for regulation of water permeability by vasopressin.

  19. Transepithelial water permeability in microperfused distal airways. Evidence for channel-mediated water transport.

    PubMed Central

    Folkesson, H G; Matthay, M A; Frigeri, A; Verkman, A S

    1996-01-01

    Water movement across the airway epithelium is important for regulation of the volume and composition of airspace fluid. A novel approach is reported here to measure osmotic and diffusional water permeability in intact airways. Small airways (100-200 microns diameter, 1-2 mm length) from guinea pig lung were microdissected and perfused in vitro using concentric glass holding and perfusion pipettes. For measurement of osmotic water permeability (Pf), the airway lumen was perfused wit PBS (300 mOsM) containing a membrane impermeable fluorophore, fluorescein sulfonate (FS), and the airway was bathed in solutions of specified osmolalities. Pf determination was based on the changes in FS fluorescence at the distal end of the airway resulting from transepithelial water transport. Pf was 4-5 x 10(-3) cm/s at 23 degrees C and independent of lumen flow rate (10-100 nl/min) and the magnitude and direction of the osmotic gradient (bath osmolality 50-600 mOsM). Temperature dependence measurements gave an activation energy of 4.4 kcal/mol (15-37 degrees C). Pf was not altered by 0.3 mM HgCl2 or 50 microM forskolin, but was increased to 31 x 10(-3) cm/s by 100 micrograms/ml amphotericin B, indicating that osmosis is not limited by unstirred layers. Diffusional water permeability (Pd) was measured by H2O/D2O (deuterium oxide) exchange using the H2O/D2O-sensitive fluorescent probe aminonapthelane trisulfonic acid in the lumen. Measured Pd was 3-6 x 10(-6) cm/s at 23 degrees C, indicating significant restriction to water diffusion by unstirred layers. Antibody localization of water channels showed strong expression of the mercurial-insensitive water channel (AQP-4) at the basolateral membrane of airway epithelial cells. These results provide functional evidence that water movement across the distal airway epithelium is mediated by water channels. PMID:8609221

  20. Transepithelial water permeability in microperfused distal airways. Evidence for channel-mediated water transport.

    PubMed

    Folkesson, H G; Matthay, M A; Frigeri, A; Verkman, A S

    1996-02-01

    Water movement across the airway epithelium is important for regulation of the volume and composition of airspace fluid. A novel approach is reported here to measure osmotic and diffusional water permeability in intact airways. Small airways (100-200 microns diameter, 1-2 mm length) from guinea pig lung were microdissected and perfused in vitro using concentric glass holding and perfusion pipettes. For measurement of osmotic water permeability (Pf), the airway lumen was perfused wit PBS (300 mOsM) containing a membrane impermeable fluorophore, fluorescein sulfonate (FS), and the airway was bathed in solutions of specified osmolalities. Pf determination was based on the changes in FS fluorescence at the distal end of the airway resulting from transepithelial water transport. Pf was 4-5 x 10(-3) cm/s at 23 degrees C and independent of lumen flow rate (10-100 nl/min) and the magnitude and direction of the osmotic gradient (bath osmolality 50-600 mOsM). Temperature dependence measurements gave an activation energy of 4.4 kcal/mol (15-37 degrees C). Pf was not altered by 0.3 mM HgCl2 or 50 microM forskolin, but was increased to 31 x 10(-3) cm/s by 100 micrograms/ml amphotericin B, indicating that osmosis is not limited by unstirred layers. Diffusional water permeability (Pd) was measured by H2O/D2O (deuterium oxide) exchange using the H2O/D2O-sensitive fluorescent probe aminonapthelane trisulfonic acid in the lumen. Measured Pd was 3-6 x 10(-6) cm/s at 23 degrees C, indicating significant restriction to water diffusion by unstirred layers. Antibody localization of water channels showed strong expression of the mercurial-insensitive water channel (AQP-4) at the basolateral membrane of airway epithelial cells. These results provide functional evidence that water movement across the distal airway epithelium is mediated by water channels.

  1. A new test method for measuring the water vapour permeability of fabrics

    NASA Astrophysics Data System (ADS)

    Huang, Jianhua; Qian, Xiaoming

    2007-09-01

    The water vapour permeability of textile fabrics is a critical determinant of wearer comfort. Existing test methods are either time consuming or require large amounts of material. A new test apparatus was developed for characterizing the water vapour permeability of fabrics. An aluminium cylinder covered with waterproof and vapour permeable PTFE laminate is used for generating water vapour source on one side of the sample. A dry nitrogen sweep gas stream is used to carry water vapour away. The calculation of the rate of water vapour transmission across the fabric is based on the measurement of the relative humidity of the outgoing nitrogen stream. This new measuring apparatus offers a short test time and calls for a small sample size. The comparison measurements show that the test results correlated well with those obtained from ISO 11092 and ASTM E96. Therefore, this test method provides a new technique to accurately and precisely characterize the water vapour transport properties of fabrics.

  2. Membrane permeability and the loss of germination factor from Neurospora crassa at low water activities

    NASA Technical Reports Server (NTRS)

    Charlang, G.; Horowitz, N. H.

    1974-01-01

    Neurospora crassa conidia incubating in buffer at low water activities release a germination-essential component as well as 260-nm absorbing and ninhydrin-positive materials, regardless of whether an electrolyte or nonelectrolyte is used to reduce water activity. Chloroform and antibiotics known to increase cell-membrane permeability have a similar effect. This suggests that membrane damage occurs in media of low water activity and that an increase in permeability is responsible for the release of cellular components. The damage caused in media of low water activity is nonlethal in most cases, and the conidia recover when transferred to nutrient medium.

  3. Membrane permeability and the loss of germination factor from Neurospora crassa at low water activities

    NASA Technical Reports Server (NTRS)

    Charlang, G.; Horowitz, N. H.

    1974-01-01

    Neurospora crassa conidia incubating in buffer at low water activities release a germination-essential component as well as 260-nm absorbing and ninhydrin-positive materials, regardless of whether an electrolyte or nonelectrolyte is used to reduce water activity. Chloroform and antibiotics known to increase cell-membrane permeability have a similar effect. This suggests that membrane damage occurs in media of low water activity and that an increase in permeability is responsible for the release of cellular components. The damage caused in media of low water activity is nonlethal in most cases, and the conidia recover when transferred to nutrient medium.

  4. Water permeability of primary mouse keratinocyte cultures grown at the air-liquid interface

    SciTech Connect

    Cumpstone, M.B.; Kennedy, A.H.; Harmon, C.S.; Potts, R.O.

    1989-04-01

    In order to study the development of the epidermal permeability barrier in vitro, tritiated water (HTO) flux was measured across murine keratinocytes cultured at the air-liquid interface. Using a micro-diffusion technique, it was shown that air-liquid cultures form areas where the water diffusion is comparable to that of intact neonatal mouse skin. When water permeability is measured over a large area of the culture surface, however, significantly higher flux is obtained. These results show that under the culture conditions used, areas of water barrier comparable to intact neonatal mouse skin coexist with regions of less complete barrier formation.

  5. Modeling relative permeability of water in soil: Application of effective-medium approximation and percolation theory

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Sahimi, Muhammad; Daigle, Hugh

    2016-07-01

    Accurate prediction of the relative permeability to water under partially saturated condition has broad applications and has been studied intensively since the 1940s by petroleum, chemical, and civil engineers, as well as hydrologists and soil scientists. Many models have been developed for this purpose, ranging from those that represent the pore space as a bundle of capillary tubes, to those that utilize complex networks of interconnected pore bodies and pore throats with various cross-section shapes. In this paper, we propose an approach based on the effective-medium approximation (EMA) and percolation theory in order to predict the water relative permeability. The approach is general and applicable to any type of porous media. We use the method to compute the water relative permeability in porous media whose pore-size distribution follows a power law. The EMA is invoked to predict the relative permeability from the fully saturated pore space to some intermediate water saturation that represents a crossover from the EMA to what we refer to as the "critical region." In the critical region below the crossover water saturation Swx, but still above the critical water saturation Swc (the residual saturation or the percolation threshold of the water phase), the universal power law predicted by percolation theory is used to compute the relative permeability. To evaluate the accuracy of the approach, data for 21 sets of undisturbed laboratory samples were selected from the UNSODA database. For 14 cases, the predicted relative permeabilities are in good agreement with the data. For the remaining seven samples, however, the theory underestimates the relative permeabilities. Some plausible sources of the discrepancy are discussed.

  6. Experimental study on the difference between gas and water permeability of clay-rich fault rocks

    NASA Astrophysics Data System (ADS)

    Duan, Qingbao; Yang, Xiaosong; Chen, Jianye

    2017-04-01

    Gas permeability of clay rich rocks is generally higher than that measured with water as the pore fluid in laboratory. Besides the Klinkenberg gas slippage effect, the swelling and adsorption of clay minerals subjected to water may have strong influences (Faulkner and Rutter, 2000; Duan and Yang, 2014). To better understand the discrepancy between gas and water permeability of clay-rich fault rocks, we performed detail fluid transport property experiments on synthetic smectite-quartz, illite-quartz mixtures and natural fault gouge, as well as clay-deplete sandstones for the comparison purpose. Experiments were conducted on a fluid flow apparatus with effective pressures cycling between 5 and 105 MPa. Each sample was subject to nine pressure cycles (the first eight with nitrogen and the last one with de-ionized water as the pore fluid), along which permeability and porosity of either the dry or water-saturated samples were measured. In a few additional experiments, X-ray diffraction (XRD) analyses were used to examine the hydration state of the smectite before and after the introduction of water. Results show that permeability of all the samples investigated decreases with increasing effective pressure, following a power law relation. Gas permeabilities exhibit strong pore pressure dependence, which can be attributed to the slippage effect. Water permeabilities of the samples are generally lower than the gas results after correction, with a few exceptions for the synthetic samples (clay content ≤10%). The permeability trends observed for samples after the introduction of water can be generally explained by the evolution of sample porosity, as can be obtained from the bulk and solid phase volume measurement results. Take the smectite-quartz synthetic samples for instance. Bulk volume of the samples generally expands after water saturation and XRD results show that almost three layers of water enter the smectite interlayers (001 basal spacing expands from about 14

  7. Water Permeability of Aquaporin-4 Channel Depends on Bilayer Composition, Thickness, and Elasticity

    PubMed Central

    Tong, Jihong; Briggs, Margaret M.; McIntosh, Thomas J.

    2012-01-01

    Aquaporin-4 (AQP4) is the primary water channel in the mammalian brain, particularly abundant in astrocytes, whose plasma membranes normally contain high concentrations of cholesterol. Here we test the hypothesis that the water permeabilities of two naturally occurring isoforms (AQP4-M1 and AQP4-M23) depend on bilayer mechanical/structural properties modulated by cholesterol and phospholipid composition. Osmotic stress measurements were performed with proteoliposomes containing AQP4 and three different lipid mixtures: 1), phosphatidylcholine (PC) and phosphatidylglycerol (PG); 2), PC, PG, with 40 mol % cholesterol; and 3), sphingomyelin (SM), PG, with 40 mol % cholesterol. The unit permeabilities of AQP4-M1 were 3.3 ± 0.4 × 10−13 cm3/s (mean ± SE), 1.2 ± 0.1 × 10−13 cm3/s, and 0.4 ± 0.1 × 10−13 cm3/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. The unit permeabilities of AQP4-M23 were 2.1 ± 0.2 × 10−13 cm3/s, 0.8 ± 0.1 × 10−13 cm3/s, and 0.3 ± 0.1 × 10−13 cm3/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. Thus, for each isoform the unit permeabilities strongly depended on bilayer composition and systematically decreased with increasing bilayer compressibility modulus and bilayer thickness. These observations suggest that altering lipid environment provides a means of regulating water channel permeability. Such permeability changes could have physiological consequences, because AQP4 water permeability would be reduced by its sequestration into SM:cholesterol-enriched raft microdomains. Conversely, under ischemic conditions astrocyte membrane cholesterol content decreases, which could increase AQP4 permeability. PMID:23199918

  8. Water permeability of aquaporin-4 channel depends on bilayer composition, thickness, and elasticity.

    PubMed

    Tong, Jihong; Briggs, Margaret M; McIntosh, Thomas J

    2012-11-07

    Aquaporin-4 (AQP4) is the primary water channel in the mammalian brain, particularly abundant in astrocytes, whose plasma membranes normally contain high concentrations of cholesterol. Here we test the hypothesis that the water permeabilities of two naturally occurring isoforms (AQP4-M1 and AQP4-M23) depend on bilayer mechanical/structural properties modulated by cholesterol and phospholipid composition. Osmotic stress measurements were performed with proteoliposomes containing AQP4 and three different lipid mixtures: 1), phosphatidylcholine (PC) and phosphatidylglycerol (PG); 2), PC, PG, with 40 mol % cholesterol; and 3), sphingomyelin (SM), PG, with 40 mol % cholesterol. The unit permeabilities of AQP4-M1 were 3.3 ± 0.4 × 10(-13) cm(3)/s (mean ± SE), 1.2 ± 0.1 × 10(-13) cm(3)/s, and 0.4 ± 0.1 × 10(-13) cm(3)/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. The unit permeabilities of AQP4-M23 were 2.1 ± 0.2 × 10(-13) cm(3)/s, 0.8 ± 0.1 × 10(-13) cm(3)/s, and 0.3 ± 0.1 × 10(-13) cm(3)/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. Thus, for each isoform the unit permeabilities strongly depended on bilayer composition and systematically decreased with increasing bilayer compressibility modulus and bilayer thickness. These observations suggest that altering lipid environment provides a means of regulating water channel permeability. Such permeability changes could have physiological consequences, because AQP4 water permeability would be reduced by its sequestration into SM:cholesterol-enriched raft microdomains. Conversely, under ischemic conditions astrocyte membrane cholesterol content decreases, which could increase AQP4 permeability.

  9. Permeability of Molecular Hydrogen and Water Vapor Through Butyl Rubber at Ambient Temperature

    SciTech Connect

    Zeigler, K.

    1992-04-09

    The preparation of the Safety Analysis Report for the 233-H Replacement Tritium Facility (RTF) requires permeation constants of hydrogen isotopes through butyl rubber, to estimate possible worker exposure given a certain level of tritium in the confinement gloveboxes. Literature values of the permeability constants for hydrogen isotopes and water vapor through butyl rubber at ambient temperature (22-25 C) have been converted to common units and are tabulated (Tables I and II). Permeation rates of tritiated species are the same as that of protium species, within experimental error. Thus, molecular protium and normal water vapor data serve to estimate tritium permeation rates. Because of vendor to vendor variability of permeability, especially of water vapor, vendor measurements of water vapor permeability should continue to be used to estimate permeation in SRS processes.

  10. Permeability of Molecular Hydrogen and Water Vapor Through Butyl Rubber at Ambient Temperature

    SciTech Connect

    Clark, Elliot A.

    1992-04-09

    The preparation of the Safety Analysis Report for the 233-H Replacement Tritium Facility (RTF) requires permeation constants of hydrogen isotopes through butyl rubber, to estimate possible worker exposure given a certain level of tritium in the confinement gloveboxes. Literature values of the permeability constants for hydrogen isotopes and water vapor through butyl rubber at ambient temperature (22-25 C) have been converted to common units and are tabulated (Tables I and II). Permeation rates of tritiated species are the same as that of protium species, within experimental error. Thus, molecular protium and normal water vapor data serve to estimate tritium permeation rates. Because of vendor-to-vendor variability of permeability, especially of water vapor, vendor measurements of water vapor permeability should continue to be used to estimate permeation in SRS processes.

  11. A model of regional ground-water flow in secondary-permeability terrane ( Susquehanna River).

    USGS Publications Warehouse

    Gerhart, J.M.

    1984-01-01

    The ground-water flow system in the Lower Susquehanna River Basin in Pennsylvania and Maryland can be considered as one complex unconfined aquifer in which secondary porosity and permeability are the dominant influences on the occurrence and flow of ground water. The degree of development of secondary porosity and permeability in the various lithologies of the lower basin determines the aquifer characteristics of each lithology. Based on qualitative evidence, the use of a porous-media model was assumed to be appropriate on a regional scale and a finite-difference ground-water flow model was constructed for the lower basin. -from Author

  12. Durable Suit Bladder with Improved Water Permeability for Pressure and Environment Suits

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Kuznetz, Larry; Orndoff, Evelyne; Tang, Henry; Aitchison, Lindsay; Ross, Amy

    2009-01-01

    Water vapor permeability is shown to be useful in rejecting heat and managing moisture accumulation in launch-and-entry pressure suits. Currently this is accomplished through a porous Gortex layer in the Advanced Crew and Escape Suit (ACES) and in the baseline design of the Constellation Suit System Element (CSSE) Suit 1. Non-porous dense monolithic membranes (DMM) that are available offer potential improvements for water vapor permeability with reduced gas leak. Accordingly, three different pressure bladder materials were investigated for water vapor permeability and oxygen leak: ElasthaneTM 80A (thermoplastic polyether urethane) provided from stock polymer material and two custom thermoplastic polyether urethanes. Water vapor, carbon dioxide and oxygen permeability of the DMM's was measured in a 0.13 mm thick stand-alone layer, a 0.08 mm and 0.05 mm thick layer each bonded to two different nylon and polyester woven reinforcing materials. Additional water vapor permeability and mechanical compression measurements were made with the reinforced 0.05 mm thick layers, further bonded with a polyester wicking and overlaid with moistened polyester fleece thermal underwear .This simulated the pressure from a supine crew person. The 0.05 mm thick nylon reinforced sample with polyester wicking layer was further mechanically tested for wear and abrasion. Concepts for incorporating these materials in launch/entry and Extravehicular Activity pressure suits are presented.

  13. Durable Suit Bladder with Improved Water Permeability for Pressure and Environment Suits

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Kuznetz, Larry; Orndoff, Evelyne; Tang, Henry; Aitchison, Lindsay; Ross, Amy

    2009-01-01

    Water vapor permeability is shown to be useful in rejecting heat and managing moisture accumulation in launch-and-entry pressure suits. Currently this is accomplished through a porous Gortex layer in the Advanced Crew and Escape Suit (ACES) and in the baseline design of the Constellation Suit System Element (CSSE) Suit 1. Non-porous dense monolithic membranes (DMM) that are available offer potential improvements for water vapor permeability with reduced gas leak. Accordingly, three different pressure bladder materials were investigated for water vapor permeability and oxygen leak: ElasthaneTM 80A (thermoplastic polyether urethane) provided from stock polymer material and two custom thermoplastic polyether urethanes. Water vapor, carbon dioxide and oxygen permeability of the DMM's was measured in a 0.13 mm thick stand-alone layer, a 0.08 mm and 0.05 mm thick layer each bonded to two different nylon and polyester woven reinforcing materials. Additional water vapor permeability and mechanical compression measurements were made with the reinforced 0.05 mm thick layers, further bonded with a polyester wicking and overlaid with moistened polyester fleece thermal underwear .This simulated the pressure from a supine crew person. The 0.05 mm thick nylon reinforced sample with polyester wicking layer was further mechanically tested for wear and abrasion. Concepts for incorporating these materials in launch/entry and Extravehicular Activity pressure suits are presented.

  14. Development of implantable hemodialysis system using PES membranes with high water-permeability.

    PubMed

    To, N; Sanada, I; Ito, H; Morita, S; Kanno, Y; Miki, N

    2015-08-01

    This paper presents development of high water-permeable dialysis membranes. We proposed the system that does not use dialysis fluid for the implantable micro dialysis treatment and development of such membranes is crucial. We developed micro dialysis system composed by nanoporous membranes and microfluidic channels in our prior work. The membranes were made of nanoporous polyethersulfone (PES), which was not water-permeable. By not using dialysate, our device can be simplified because the pumps and storage tanks for the dialysis fluid are not necessary. This treatment is termed as hemofiltration. We measured the water permeability of PES membrane with respect to the concentrations of the PES, the additives, and the solvents in the casting solution. We could find the membranes with sufficiently high water permeability through in vitro experiments using a syringe pomp and whole cow blood, and the membrane had enough mechanical strength. We conducted experiments with multi-layered device in in vitro and in vivo using rats, where the system was connected to the vein and artery. We successfully collected the filtrate beyond target line, which was set by a medical doctor, without any leakage of blood from the device. The results verified that the filtration device can be scaled-up by increasing a number of the layer. We connected the device to a rat for 5h. It was verified the device maintained almost constant water permeability beyond our target line.

  15. High-pressure homogenization lowers water vapor permeability of soybean protein isolate-beeswax films.

    PubMed

    Zhang, Chao; Ma, Yue; Guo, Kuan; Zhao, Xiaoyan

    2012-03-07

    Soybean-protein isolate (SPI) has excellent film-forming capacity. However, the water vapor permeability of SPI film is high, which will cause the moisture lose of packaged products. The effect of high-pressure homogenization (HPH) on the water vapor permeability of SPI-beeswax films was evaluated. The HPH was effective at lowering the water vapor permeability of SPI-beeswax films to about 50% of the control. The HPH reduced the particle size of films and made their matrix more compact. The HPH improved the hydrophobicity of SPI-beeswax films. For the first time, we proved that the HPH improved the bound-beeswax content in SPI-beeswax films. The bound beeswax was effective at lowering the water vapor permeability of films rather than the free beeswax in the film matrix. In summary, the HPH lowered water vapor permeability of SPI-beeswax films by reducing their particle size and raising their hydrophobicity and bound-beeswax content.

  16. A study of relative permeability for steam-water flow in porous media

    SciTech Connect

    Ambusso, Willis; Satik, Cengiz; Horne, Roland

    1996-01-24

    We report on continuing experimental and numerical efforts to obtain steam-water relative permeability functions and to assess effect of heat transfer and phase change. To achieve these, two sets of steady-state flow experiments were conducted: one with nitrogen and water and another with steam and water. During these experiments, a mixture of nitrogen-water (or steam-water) was injected into a Berea sandstone core. At the onset of steady state conditions, three-dimensional saturation distributions were obtained by using a high resolution X-ray computer tomography scanner. By identifying a length of the core over which a flat saturation profile exists and measuring the pressure gradient associated with this length, we calculated relative permeabilities for nitrogen-water flow experiments. The relative permeability relations obtained in this case were in good agreement with those reported by other investigators. Another attempt was also made to conduct a steam-water flow experiment under adiabatic conditions. This experiment was completed with partial success due to the difficulties encountered during the experiment. The results of this experiment showed that a flat saturation profile actually developed over a substantial length of the core even at a comparatively modest injection rate (6 grams per minute) with low steam quality (4% by mass). The completion of this set of experiments should yield steam-water relative permeability relations in the near future.

  17. Using permeable membranes to produce hydrogen and oxygen from water

    NASA Technical Reports Server (NTRS)

    Sanders, A. P.; Williams, R. J.; Downs, W. R.; Mcbryar, H.

    1975-01-01

    Concept may make it profitable to obtain hydrogen fuel from water. Laboratory tests have demonstrated that method enables decomposition of water several orders of magnitude beyond equilibrium state where only small amounts of free hydrogen are present.

  18. Expression of aquaporin1, a water channel protein, in cytoplasm is negatively correlated with prognosis of breast cancer patients.

    PubMed

    Qin, Fengxia; Zhang, Huikun; Shao, Ying; Liu, Xiaoli; Yang, Limin; Huang, Yong; Fu, Li; Gu, Feng; Ma, Yongjie

    2016-02-16

    Aquaporin1 (AQP1) belongs to a highly conserved family of aquaporin proteins which facilitate water flux across cell membranes. Although emerging evidences indicated the cytoplasm was important for AQP1 localization, the function of AQP1 corresponding to its cytoplasmic distribution has rarely been explored until present. In our clinical study, we reported for the first time that AQP1 was localized dominantly in the cytoplasm of cancer cells of invasive breast cancer patients and cytoplasmic AQP1 was an independent prognostic factor. High expression of AQP1 indicated a shorter survival, especially in luminal subtype. Moreover, in line with our findings in clinic, cytoplasmic expression of AQP1 was further validated in both primary cultured breast cancer cells and AQP1 over-expressing cell lines, in which the functional importance of cytoplasmic AQP1 was confirmed in vitro. In conclusion, our study provided the first evidence that cytoplasmic expression of AQP1 promoted breast cancer progression and it could be a potential prognostic biomarker for breast cancer.

  19. Effect of monoglyceride structure and cholesterol content on water permeability of the droplet bilayer.

    PubMed

    Michalak, Zuzanna; Muzzio, Michelle; Milianta, Peter J; Giacomini, Rosario; Lee, Sunghee

    2013-12-23

    The process of water permeation across lipid membranes has significant implications for cellular physiology and homeostasis, and its study may lead to a greater understanding of the relationship between the structure of lipid bilayer and the role that lipid structure plays in water permeation. In this study, we formed a droplet interface bilayer (DIB) by contacting two aqueous droplets together in an immiscible solvent (squalane) containing bilayer-forming surfactant (monoglycerides). Using the DIB model, we present our results on osmotic water permeabilities and activation energy for water permeation of an associated series of unsaturated monoglycerides as the principal component of droplet bilayers, each having the same chain length but differing in the position and number of double bonds, in the absence and presence of a varying concentration of cholesterol. Our findings suggest that the tailgroup structure in a series of monoglyceride bilayers is seen to affect the permeability and activation energy for the water permeation process. Moreover, we have also established the insertion of cholesterol into the droplet bilayer, and have detected its presence via its effect on water permeability. The effect of cholesterol differs depending on the type of monoglyceride. We demonstrate that the DIB can be employed as a convenient model membrane to rapidly explore subtle structural effects on bilayer water permeability.

  20. Water- and cryoprotectant-permeability of mature and immature oocytes in the medaka (Oryzias latipes).

    PubMed

    Valdez, Delgado M; Miyamoto, Akira; Hara, Takao; Seki, Shinsuke; Kasai, Magosaburo; Edashige, Keisuke

    2005-02-01

    The permeability of the plasma membrane plays a crucial role in the successful cryopreservation of oocytes/embryos. To identify a stage feasible for the cryopreservation of teleost oocytes, we investigated the permeability to water and various cryoprotectants of medaka (Oryzias latipes) oocytes at the germinal vesicle (GV) and metaphase II (MII) stages. In sucrose solutions, the volume changes were greater in GV oocytes than MII oocytes. Estimated values for osmotically inactive volume were 0.41 for GV oocytes and 0.74 for MII oocytes. Water-permeability (microm/min/atm) at 25 degrees C was higher in GV oocytes (0.13+/-0.01) than MII oocytes (0.06+/-0.01). The permeability of MII oocytes to various cryoprotectants (glycerol, propylene glycol, ethylene glycol, and DMSO) was quite low because the oocytes remained shrunken during 2 h of exposure in the cryoprotectant solutions at 25 degrees C. When the chorion of MII oocytes was removed, the volume change was not affected, except in DMSO solution, where dechorionated oocytes shrunk and then regained their volume slowly; the P(DMSO) value was estimated to be 0.14+/-0.01x10(-3) cm/min. On the other hand, the permeability of GV oocytes to cryoprotectants were markedly high, the P(s) values (x10(-3) cm/min) for propylene glycol, ethylene glycol, and DMSO being 2.21+/-0.29, 1.36+/-0.18, and 1.19+/-0.01, respectively. However, the permeability to glycerol was too low to be estimated, because GV oocytes remained shrunken after 2 h of exposure in glycerol solution. These results suggest that, during maturation, medaka oocytes become less permeable to water and to small neutral solutes, probably by acquiring resistance to hypotonic conditions before being spawned in fresh water. Since such changes would make it difficult to cryopreserve mature oocytes, immature oocytes would be more suitable for the cryopreservation of teleosts.

  1. Energetic and molecular water permeation mechanisms of the human red blood cell urea transporter B.

    PubMed

    Azouzi, Slim; Gueroult, Marc; Ripoche, Pierre; Genetet, Sandrine; Colin Aronovicz, Yves; Le Van Kim, Caroline; Etchebest, Catherine; Mouro-Chanteloup, Isabelle

    2013-01-01

    Urea transporter B (UT-B) is a passive membrane channel that facilitates highly efficient permeation of urea. In red blood cells (RBC), while the major function of UT-B is to transport urea, it is assumed that this protein is able to conduct water. Here, we have revisited this last issue by studying RBCs and ghosts from human variants with defects of aquaporin 1 (AQP1) or UT-B. We found that UT-B's osmotic water unit permeability (pfunit) is similar to that of AQP1. The determination of diffusional permeability coefficient (Pd) allowed the calculation of the Pf/Pd ratio, which is consistent with a single-file water transport. Molecular dynamic simulations of water conduction through human UT-B confirmed the experimental finding. From these results, we propose an atomistic description of water-protein interactions involved in this permeation. Inside the UT-B pore, five water molecules were found to form a single-file and move rapidly along a channel by hydrogen bond exchange involving two critical threonines. We further show that the energy barrier for water located in the central region coincides with a water dipole reorientation, which can be related to the proton exclusion observed experimentally. In conclusion, our results indicate that UT-B should be considered as a new member of the water channel family.

  2. Osmotic water permeability of plasma and vacuolar membranes in protoplasts II: theoretical basis.

    PubMed

    Kuwagata, Tsuneo; Murai-Hatano, Mari

    2007-03-01

    Water permeability of the plasma membrane (PM) and the vacuolar membrane (VM) is important for intracellular and transcellular water movement in plants, because mature plant cells have large central vacuoles. We have developed a new method for measuring the osmotic water permeability of the PM and VM (P ( f1) and P ( f2), respectively) in individual plant cells. Here, the theoretical basis and procedure of the method are discussed. Protoplasts isolated from higher plant tissues are used to measure P ( f1) and P ( f2). Because of the semi-permeability (selective permeability) of cellular membranes, protoplasts swell or shrink under hypotonic or hypertonic conditions. A theoretical three-compartment model is presented for simulating time-dependent volume changes in the vacuolar and cytoplasmic spaces in a protoplast during osmotic excursions. The model describes the theoretical relationships between P ( f1), P ( f2) and the bulk osmotic water permeability of protoplasts (P ( f(bulk))). The procedure for measuring the osmotic water permeability is: (1) P ( f(bulk)) is calculated from the time when half of the total change in protoplast volume is completed, by assuming that the protoplast has a single barrier to water movement across it (two-compartment model); (2) P ( f2) of vacuoles isolated from protoplasts is obtained in the same manner; and (3) P ( f1) is determined from P ( f(bulk)) and P ( f2) according to the three-compartment model. The theoretical relationship between P ( fl ) (m s(-1)) and L ( Pl ) (hydraulic conductivity, l=1, 2) (m s(-1) Pa(-1)) is also discussed.

  3. The Water and Nonelectrolyte Permeability Induced in Thin Lipid Membranes by the Polyene Antibiotics Nystatin and Amphotericin B

    PubMed Central

    Holz, Ronald; Finkelstein, Alan

    1970-01-01

    Nystatin and amphotericin B increase the permeability of thin (<100 A) lipid membranes to ions, water, and nonelectrolytes. Water and nonelectrolyte permeability increase linearly with membrane conductance (i.e., ion permeability). In the unmodified membrane, the osmotic permeability coefficient, Pf, is equal to the tagged water permeability coefficient, (Pd)w; in the nystatin- or amphotericin B-treated membrane, Pf/(Pd)w ≈ 3. The unmodified membrane is virtually impermeable to small hydrophilic solutes, such as urea, ethylene glycol, and glycerol; the nystatin- or amphotericin B-treated membrane displays a graded permeability to these solutes on the basis of size. This graded permeability is manifest both in the tracer permeabilities, Pd, and in the reflection coefficients, σ (Table I). The "cutoff" in permeability occurs with molecules about the size of glucose (Stokes-Einstein radius ≊ 4 A). We conclude that nystatin and amphotericin B create aqueous pores in thin lipid membranes; the effective radius of these pores is approximately 4 A. There is a marked similarity between the permeability of a nystatin- or amphotericin B-treated membrane to water and small hydrophilic solutes and the permeability of the human red cell membrane to these same molecules. PMID:5514158

  4. Liquid CO2 displacement of water in a dual-permeability pore network micromodel.

    PubMed

    Zhang, Changyong; Oostrom, Mart; Grate, Jay W; Wietsma, Thomas W; Warner, Marvin G

    2011-09-01

    Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO(2) (LCO(2))-water displacement was evaluated in a pore network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over 2 orders of magnitude. LCO(2) displaced water only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO(2) displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO(2) saturation (S(LCO2)) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO(2) resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict S(LCO2) in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated S(LCO2).

  5. Liquid CO2 Displacement of Water in a Dual-Permeability Pore Network Micromodel

    SciTech Connect

    Zhang, Changyong; Oostrom, Martinus; Grate, Jay W.; Wietsma, Thomas W.; Warner, Marvin G.

    2011-09-01

    Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO2 (LCO2) - water displacement was evaluated in a pore network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over two orders of magnitude. LCO2 displaced water only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO2 displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO2 saturation (SLCO2) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO2 resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict SLCO2 in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated SLCO2.

  6. Energetic and Molecular Water Permeation Mechanisms of the Human Red Blood Cell Urea Transporter B

    PubMed Central

    Azouzi, Slim; Gueroult, Marc; Ripoche, Pierre; Genetet, Sandrine; Colin Aronovicz, Yves; Le Van Kim, Caroline; Etchebest, Catherine; Mouro-Chanteloup, Isabelle

    2013-01-01

    Urea transporter B (UT-B) is a passive membrane channel that facilitates highly efficient permeation of urea. In red blood cells (RBC), while the major function of UT-B is to transport urea, it is assumed that this protein is able to conduct water. Here, we have revisited this last issue by studying RBCs and ghosts from human variants with defects of aquaporin 1 (AQP1) or UT-B. We found that UT-B's osmotic water unit permeability (pfunit) is similar to that of AQP1. The determination of diffusional permeability coefficient (Pd) allowed the calculation of the Pf/Pd ratio, which is consistent with a single-file water transport. Molecular dynamic simulations of water conduction through human UT-B confirmed the experimental finding. From these results, we propose an atomistic description of water–protein interactions involved in this permeation. Inside the UT-B pore, five water molecules were found to form a single-file and move rapidly along a channel by hydrogen bond exchange involving two critical threonines. We further show that the energy barrier for water located in the central region coincides with a water dipole reorientation, which can be related to the proton exclusion observed experimentally. In conclusion, our results indicate that UT-B should be considered as a new member of the water channel family. PMID:24376529

  7. Water permeability in hydrate-bearing sediments: A pore-scale study

    NASA Astrophysics Data System (ADS)

    Dai, Sheng; Seol, Yongkoo

    2014-06-01

    Permeability is a critical parameter governing methane flux and fluid flow in hydrate-bearing sediments; however, limited valid data are available due to experimental challenges. Here we investigate the relationship between apparent water permeability (k') and hydrate saturation (Sh), accounting for hydrate pore-scale growth habit and meso-scale heterogeneity. Results from capillary tube models rely on cross-sectional tube shapes and hydrate pore habits, thus are appropriate only for sediments with uniform hydrate distribution and known hydrate pore character. Given our pore network modeling results showing that accumulating hydrate in sediments decreases sediment porosity and increases hydraulic tortuosity, we propose a modified Kozeny-Carman model to characterize water permeability in hydrate-bearing sediments. This model agrees well with experimental results and can be easily implemented in reservoir simulators with no empirical variables other than Sh. Results are also relevant to flow through other natural sediments that undergo diagenesis, salt precipitation, or bio-clogging.

  8. Transient and steady state expansions for water infiltration into dual permeability soils

    NASA Astrophysics Data System (ADS)

    Lassabatere, Laurent; Di Prima, Simone; Angulo-Jaramillo, Rafael; Iovino, Massimo; Bagarello, Vincenzo

    2017-04-01

    In the vadose zone, preferential flow in strongly heterogeneous soils is more the rule than homogeneous flow in uniform soils. Consequently, research activity has recently focused on the investigation and the modeling of preferential flow in heterogeneous soils and the characterization of hydraulic properties of heterogeneous soils including dual permeability soils. Within this framework, some studies have investigated the quantification of water infiltration at the surface of dual-permeability soils (Lassabatere et al., 2014). These authors developed a new analytical model for water infiltration into dual-permeability soils. However, the proposed model is based on an implicit formulation quite tricky to compute. In this study, we proposed new explicit approximate expansions for transient and steady states for the model of Lassabatere et al. (2014). The proposed methodology to compute these approximations is based on the methodology proposed by Haverkamp et al. (1994) for modeling water infiltration at the surface of single permeability soils. The main point to overcome is related the fact, in dual-permeability soils, the two subdomains, namely the fracture and the matrix domains, may have contrasting time intervals for transient and steady states. More explicitly, quasi-steady state flow may be reached in advance in the fracture domain. Consequently, at a given time, there may be the concomitancy of steady state in the fracture domain and transient state in the matrix. This point is developed further with mathematical and practical consideration. Approximate expansions and related validity time intervals are clearly identified and discussed with regards to both numerically generated and experimental data. Haverkamp R, Ross PJ, Smettem KRJ, Parlange JY (1994) 3-Dimensional analysis of infiltration from the disc Infiltrometer .2. Physically-based infiltration equation. Water Resour Res 30:2931-2935. Lassabatere L, Yilmaz D, Peyrard X, et al (2014) New analytical

  9. A multi-level pore-water sampler for permeable sediments

    USGS Publications Warehouse

    Martin, J.B.; Hartl, K.M.; Corbett, D.R.; Swarzenski, P.W.; Cable, J.E.

    2003-01-01

    The construction and operation of a multi-level piezometer (multisampler) designed to collect pore water from permeable sediments up to 230 cm below the sediment-water interface is described. Multisamplers are constructed from 1 1/2 inch schedule 80 PVC pipe. One-quarter-inch flexible PVC tubing leads from eight ports at variable depths to a 1 1/2 inch tee fitting at the top of the PVC pipe. Multisamplers are driven into the sediments using standard fence-post drivers. Water is pumped from the PVC tubing with a peristaltic pump. Field tests in Banana River Lagoon, Florida, demonstrate the utility of multisamplers. These tests include collection of multiple samples from the permeable sediments and reveal mixing between shallow pore water and overlying lagoon water.

  10. GROUND WATER REMEDIATION RESEARCH: PERMEABLE REACTIVE BARRIERS AND SOURCE ZONE REMEDIATION

    EPA Science Inventory

    An overview of ground water remediation research conducted at the Subsurface Protection and Remediation Division is provided. The focus of the overview is on Permeable Reactive Barriers for treatment of organic and inorganic contaminants and remediation of DNAPL source zones.

  11. A probabilistic approach for estimating water permeability in pressure-driven membranes.

    PubMed

    Boateng, Linkel K; Madarshahian, Ramin; Yoon, Yeomin; Caicedo, Juan M; Flora, Joseph R V

    2016-08-01

    A probabilistic approach is proposed to estimate water permeability in a cellulose triacetate (CTA) membrane. Water transport across the membrane is simulated in reverse osmosis mode by means of non-equilibrium molecular dynamics (MD) simulations. Different membrane configurations obtained by an annealing MD simulation are considered and simulation results are analyzed by using a hierarchical Bayesian model to obtain the permeability of the different membranes. The estimated membrane permeability is used to predict full-scale water flux by means of a process-level Monte Carlo simulation. Based on the results, the parameters of the model are observed to converge within 5-ns total simulation time. The results also indicate that the use of unique structural configurations in MD simulations is essential to capture realistic membrane properties at the molecular scale. Furthermore, the predicted full-scale water flux based on the estimated permeability is within the same order of magnitude of bench-scale experimental measurement of 1.72×10(-5) m/s.

  12. GROUND WATER REMEDIATION RESEARCH: PERMEABLE REACTIVE BARRIERS AND SOURCE ZONE REMEDIATION

    EPA Science Inventory

    An overview of ground water remediation research conducted at the Subsurface Protection and Remediation Division is provided. The focus of the overview is on Permeable Reactive Barriers for treatment of organic and inorganic contaminants and remediation of DNAPL source zones.

  13. COST ANALYSIS OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF GROUND WATER

    EPA Science Inventory

    The U. S. Environmental Protection Agency's Office of Research and Development and its contractor have evaluated cost data from 22 sites where permeable reactive barriers (PRBs) have been utilized to remediate contaminated ground water resources. Most of the sites evaluated wer...

  14. COST ANALYSIS OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF GROUND WATER

    EPA Science Inventory

    The U. S. Environmental Protection Agency's Office of Research and Development and its contractor have evaluated cost data from 22 sites where permeable reactive barriers (PRBs) have been utilized to remediate contaminated ground water resources. Most of the sites evaluated wer...

  15. Water vapor permeability, mechanical, optical and sensorial properties of plasticized guar gumedible films

    USDA-ARS?s Scientific Manuscript database

    Edible films were prepared by casting method using guar gum and glycerol in different ratios. The concentration of guar gum was 1.0, 1.5 and 2.0% whereas glycerol concentration was 20, 30 and 40% (w/v). The water vapor permeability (WVP), mechanical properties (tensile strength and elongation), thic...

  16. Permeability of methane, carbon dioxide and water in PA11 and PVDF used for flexible pipes

    SciTech Connect

    Andersen, T.R.; Skar, J.I.; Hansteen, C.

    1999-11-01

    Permeability of methane, carbon dioxide and water in plasticized polyvinylidene fluoride (PVDF) and plasticized polyarnid 11 (PA11 ) has been measured for a number of temperatures and pressures in a small scale test apparatus and permeability coefficients have been calculated. The results have been used to predict if the annulus of flexible pipes will be water wet. For verification of the small scale test, a large scale test has also been carried out in a 50 mm flexible pipe. Both test methods show that the annulus of flexible pipes will be water wet when carrying gas and water. This implies that the conditions in the annulus will be corrosive when pipes are carrying gas which contains carbon dioxide or hydrogen sulfide. The corrosive conditions and corrosion fatigue must be taken into account when the fatigue life of flexible risers is calculated.

  17. Convective Evaporation Through Water-Permeable Membranes for Rapid Beverage Chilling

    DTIC Science & Technology

    2008-12-01

    utilizing evaporation, a beverage chiller can achieve efficiencies above and beyond vapor compression and the Carnot Cycle . Using evaporation, a flow of...compression system which has a COP of about 3-6 and exceeds Carnot efficiency by 324 percent. 2.7 Water Temperature Due to the preferred use of...CONVECTIVE EVAPORATION THROUGH WATER -PERMEABLE MEMBRANES FOR RAPID BEVERAGE CHILLING Dr. M. Izenson* and Dr. W. Chen, Creare Inc. Hanover

  18. Importance of Residual Water Permeability on the Excretion of Water during Water Diuresis in Rats

    PubMed Central

    Cheema-Dhadli, Surinder; Chong, Chee Keong; Kim, Namhee; Kamel, Kamel S

    2010-01-01

    When the concentration of sodium (Na+) in arterial plasma (PNa) declines sufficiently to inhibit the release of vasopressin, water will be excreted promptly when the vast majority of aquaporin 2 water channels (AQP2) have been removed from luminal membranes of late distal nephron segments. In this setting, the volume of filtrate delivered distally sets the upper limit on the magnitude of the water diuresis. Since there is an unknown volume of water reabsorbed in the late distal nephron, our objective was to provide a quantitative assessment of this parameter. Accordingly, rats were given a large oral water load, while minimizing non-osmotic stimuli for the release of vasopressin. The composition of plasma and urine were measured. The renal papilla was excised during the water diuresis to assess the osmotic driving force for water reabsorption in the inner medullary collecting duct. During water diuresis, the concentration of creatinine in the urine was 13-fold higher than in plasma, which implies that ~8% of filtered water was excreted. The papillary interstitial osmolality was 600 mOsm/L > the urine osmolality. Since 17% of filtered water is delivered to the earliest distal convoluted tubule micropuncture site, we conclude that half of the water delivered to the late distal nephron is reabsorbed downstream during water diuresis. The enormous osmotic driving force for the reabsorption of water in the inner medullary collecting duct may play a role in this reabsorption of water. Possible clinical implications are illustrated in the discussion of a case example. PMID:21468191

  19. Changes in permeability of the Nojima fault damage zone inferred from repeated water injection experiments

    NASA Astrophysics Data System (ADS)

    Kitagawa, Yuichi; Kano, Yasuyuki

    2016-11-01

    In 1995, the Hyogoken-Nanbu earthquake ( M 7.3) ruptured the Nojima fault, Awaji Island, central Japan. To investigate the recovery process of a fault zone after a large earthquake, repeated water injection experiments have been conducted every few years in an 1800-m-long borehole near the Nojima fault since 1997. In addition, the groundwater discharge rate and pressure have been observed in an 800-m borehole. From the resulting data, the macroscopic permeability of the fault fracture zone was estimated to range roughly from 1 × 10-6 to 2 × 10-6 m/s. The macroscopic permeability of the fault fracture zone decreased until 2003, and then, it stabilized or increased slightly through 2006. These changes in permeability indicate that the fault fracture zone stabilized within 8 years after the occurrence of the earthquake.[Figure not available: see fulltext.

  20. Highly water-permeable type I alveolar epithelial cells confer high water permeability between the airspace and vasculature in rat lung

    PubMed Central

    Dobbs, Leland G.; Gonzalez, Robert; Matthay, Michael A.; Carter, Ethan P.; Allen, Lennell; Verkman, A. S.

    1998-01-01

    Water permeability measured between the airspace and vasculature in intact sheep and mouse lungs is high. More than 95% of the internal surface area of the lung is lined by alveolar epithelial type I cells. The purpose of this study was to test whether osmotic water permeability (Pf) in type I alveolar epithelial cells is high enough to account for the high Pf of the intact lung. Pf measured between the airspace and vasculature in the perfused fluid-filled rat lung by the pleural surface fluorescence method was high (0.019 ± 0.004 cm/s at 12°C) and weakly temperature-dependent (activation energy 3.7 kcal/mol). To resolve the contributions of type I and type II alveolar epithelial cells to lung water permeability, Pf was measured by stopped-flow light scattering in suspensions of purified type I or type II cells obtained by immunoaffinity procedures. In response to a sudden change in external solution osmolality from 300 to 600 mOsm, the volume of type I cells decreased rapidly with a half-time (t1/2) of 60–80 ms at 10°C, giving a plasma membrane Pf of 0.06–0.08 cm/s. Pf in type I cells was independent of osmotic gradient size and was weakly temperature-dependent (activation energy 3.4 kcal/mol). In contrast, t1/2 for type II cells in suspension was much slower, ≈1 s; Pf for type II cells was 0.013 cm/s. Vesicles derived from type I cells also had a very high Pf of 0.06–0.08 cm/s at 10°C that was inhibited 95% by HgCl2. The Pf in type I cells is the highest measured for any mammalian cell membrane and would account for the high water permeability of the lung. PMID:9501203

  1. Highly permeable polymeric membranes based on the incorporation of the functional water channel protein Aquaporin Z

    PubMed Central

    Kumar, Manish; Grzelakowski, Mariusz; Zilles, Julie; Clark, Mark; Meier, Wolfgang

    2007-01-01

    The permeability and solute transport characteristics of amphiphilic triblock-polymer vesicles containing the bacterial water-channel protein Aquaporin Z (AqpZ) were investigated. The vesicles were made of a block copolymer with symmetric poly-(2-methyloxazoline)-poly-(dimethylsiloxane)-poly-(2-methyloxazoline) (PMOXA15-PDMS110-PMOXA15) repeat units. Light-scattering measurements on pure polymer vesicles subject to an outwardly directed salt gradient in a stopped-flow apparatus indicated that the polymer vesicles were highly impermeable. However, a large enhancement in water productivity (permeability per unit driving force) of up to ≈800 times that of pure polymer was observed when AqpZ was incorporated. The activation energy (Ea) of water transport for the protein-polymer vesicles (3.4 kcal/mol) corresponded to that reported for water-channel-mediated water transport in lipid membranes. The solute reflection coefficients of glucose, glycerol, salt, and urea were also calculated, and indicated that these solutes are completely rejected. The productivity of AqpZ-incorporated polymer membranes was at least an order of magnitude larger than values for existing salt-rejecting polymeric membranes. The approach followed here may lead to more productive and sustainable water treatment membranes, whereas the variable levels of permeability obtained with different concentrations of AqpZ may provide a key property for drug delivery applications. PMID:18077364

  2. Applications of permeable barrier technology to ground water contamination at the Shiprock, NM, UMTRA site

    SciTech Connect

    Thomson, B.M.; Henry, E.J.; Thombre, M.S.

    1996-12-31

    The Shiprock uranium mill tailings pile in far northwestern New Mexico consists of approximately 1.5 million tons of uranium mill tailings from an acid leach mill which operated from 1954 to 1968. Located on land owned by the Navajo Nation, it was one of the first tailings piles stabilized under the Uranium Mill Tailings Remedial Action (UMTRA) project. Stabilization activities were completed in 1986 and consisted principally of consolidating the tailings, contouring the pile to achieve good drainage, and covering the pile with a multi-layer cap to control infiltration of water, radon emanation, and surface erosion. No ground water protection or remediation measures were implemented other than limiting infiltration of water through the pile, although a significant ground water contamination plume exists in the flood plain adjacent to the San Juan River. The major contaminants at the Shiprock site include high concentrations of sulfate, nitrate, arsenic, and uranium. One alternative for remediation may be the use of a permeable barrier in the flood plain aquifer. As proposed for the Shiprock site, the permeable barrier would be a trench constructed in the flood plain that would be backfilled with a media that is permeable to ground water, but would intercept or degrade the pollutants. Work to date has focused on use of a mixed microbial population of sulfate and nitrate reducing organisms. These organisms would produce strongly reducing conditions which would result in precipitation of the metal contaminants (i.e., Se(IV) and U(IV)) in the barrier. One of the first considerations in designing a permeable barrier is developing an understanding of ground water flow at the site. Accordingly, a steady state numerical model of the ground water flow at the site was developed using the MODFLOW code.

  3. Characterization of ionic permeability and water vapor transmission rate of polymers used for implantable electronics.

    PubMed

    Kirsten, Sabine; Schubert, Martin; Uhlemann, Jürgen; Wolter, Klaus-Jurgen

    2014-01-01

    Biocompatible polymers used as encapsulation and packaging materials for implantable electronic devices have to comply with numerous requirements. Especially their barrier properties against water molecules and ions are of particular interest regarding the reliability of the encapsulation as well as functional integrity of the electronic components since water and ions on the circuit board may evoke corrosion, leakage current and finally the failure of the device. This paper describes a measurement setup to investigate the ionic permeability under in vitro conditions of polymeric membranes manufactured from various biocompatible polymers. Ionic permeability and water vapor transmission rate representing the barrier properties of these membranes were investigated. First results were obtained for polyimide, silicone, polyether ether ketone and polyamide, whereas polyimide evinced the best properties.

  4. The water permeability of lens aquaporin-0 depends on its lipid bilayer environment.

    PubMed

    Tong, Jihong; Canty, John T; Briggs, Margaret M; McIntosh, Thomas J

    2013-08-01

    Aquaporin-0 (AQP0), the primary water channel in lens fiber cells, is critical to lens development, organization, and function. In the avascular lens there is thought to be an internal microcirculation associated with fluid movement. Although AQP0 is known to be important in fluid fluxes across membranes, the water permeability of this channel has only been measured in Xenopus oocytes and in outer lens cortical membranes, but not in inner nuclear membranes, which have an increased cholesterol/phospholipid ratio. Here we measure the unit water permeability of AQP0 in different proteoliposomes with cholesterol/phospholipid ratios and external pHs similar to those found in the cortex and nucleus of the lens. Osmotic stress measurements were performed with proteoliposomes containing AQP0 and three different lipids mixtures: (1) phosphatidylcholine (PC) and phosphatidylglycerol (PG), (2) PC, PG, with 40 mol% cholesterol, and (3) sphingomyelin (SM), PG, with 40 mol% cholesterol. At pH 7.5 the unit permeabilities of AQP0 were 3.5 ± 0.5 × 10(-14) cm(3)/s (mean ± SEM), 1.1 ± 0.1 × 10(-14) cm(3)/s, and 0.50 ± 0.04 × 10(-14) cm(3)/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. For lipid mixtures at pH 6.5, corresponding to conditions found in the lens nucleus, the AQP0 permeabilities were 1.5 ± 0.4 × 10(-14) cm(3)/s and 0.76 ± 0.03 × 10(-14) cm(3)/s in PC:PG:cholesterol and SM:PG:cholesterol, respectively. Thus, although AQP0 unit permeability can be modified by changes in pH, it is also sensitive to changes in bilayer lipid composition, and decreases with increasing cholesterol and SM content. These data imply that AQP0 water permeability is regulated by bilayer lipid composition, so that AQP0 permeability would be significantly less in the lens nucleus than in the lens cortex.

  5. The effect of adrenalectomy on water permeability in rat papillary collecting duct.

    PubMed

    Ray, C; Carney, S; Gillies, A

    1994-05-01

    1. Chronic adrenal insufficiency impairs maximal urine concentration, probably in part due to reduced medullary tonicity but also possibly by inhibition of distal nephron water transport. This latter defect has been demonstrated in rabbit but not in rat. 2. Since the time between adrenalectomy and experiment was different in rabbit and rat studies, diffusional water permeability was evaluated in the papillary collecting duct in the absence and presence of submaximal (20 microU/mL) and supramaximal (200 microU/mL) arginine vasopressin (AVP) in adrenalectomized rats at 7, 14 and 21 days. 3. Experimentation 7 days after adrenalectomy failed to demonstrate significantly altered basal or AVP-induced water permeability which increased by 23 and 78% with submaximal and supramaximal concentrations, respectively. Submaximal AVP concentrations also induced a comparable change in water permeability in adrenalectomized rats at 14 days; however, 21 days after adrenalectomy, diffusional water permeability was not increased by 20 microU/mL AVP (3.31 +/- 0.22 to 3.31 +/- 0.24 microns/s). Nevertheless, the effect of a supramaximal AVP concentration (200 microU/mL) was not altered by adrenalectomy (4.54 +/- 0.39 to 8.08 +/- 0.96; P < 0.01). Incubation of collecting ducts in aldosterone for 2 h did not reverse the inhibitory effect of chronic adrenalectomy on AVP-stimulated water transport. 4. These studies suggest that mineralocorticoid withdrawal does impair the hydro-osmotic action of AVP in the rat papillary collecting duct but that this effect takes between 14 and 21 days to occur.

  6. Localization of the FA-CHIP water channel in frog urinary bladder.

    PubMed

    Abrami, L; Gobin, R; Berthonaud, V; Thanh, H L; Chevalier, J; Ripoche, P; Verbavatz, J M

    1997-07-01

    Like mammalian kidney collecting duct, the water permeability of frog urinary bladder epithelial cells is antidiuretic hormone (ADH)-sensitive. In kidney, this permeability is mediated by water channels named aquaporins. We recently reported the cloning of the frog aquaporin CHIP (FA-CHIP), a water channel from frog urinary bladder. FA-CHIP has 79% identity with rat Aquaporin 1 (AQP1) and only 42% identity with the kidney collecting duct Aquaporin 2 (AQP2). The purpose of this study was to examine the localization of FA-CHIP in frog urinary bladder. We raised antibodies against peptides of 15 to 17 residues, encompassing the N-ter and C-ter regions of FA-CHIP. Anti-FA-CHIP antibodies were used for Western blotting, indirect immunofluorescence microscopy and gold labeling electron microscopy in urinary bladder and other frog tissues. By Western blotting of frog urinary bladder total homogenate, the antibodies recognized a band of 29 kDa and glycosylated forms of the protein between 40 and 70 kDa. No signal was found on membrane preparations from epithelial cell homogenate. FA-CHIP was also found in frog skin, brain, gall bladder, and lung. In immunofluorescence microscopy on urinary bladder sections, FA-CHIP was localized to endothelial cells of blood capillaries and on mesothelial cells of the serosal face. Red blood cells, epithelial and basal cells were unstained. The localization of FA-CHIP in cell plasma membranes was confirmed by gold labeling electron microscopy. In other positive tissues, FA-CHIP was also localized to capillaries. In brain, plasma membranes of epithelial cells were also stained. In conclusion, like its mammalian homologue AQP1, FA-CHIP appears to be localized to constitutively water permeable cells of frog. Therefore, it belongs to the AQP1 family of proteins although unlike AQP1, FA-CHIP is absent from red blood cells and kidney. In frog urinary bladder and skin, FA-CHIP probably plays an important role in water transport across the

  7. High microvascular endothelial water permeability in mouse lung measured by a pleural surface fluorescence method.

    PubMed Central

    Carter, E P; Olveczky, B P; Matthay, M A; Verkman, A S

    1998-01-01

    Transport of water between the capillary and airspace compartments in lung encounters serial barriers: the alveolar epithelium, interstitium, and capillary endothelium. We previously reported a pleural surface fluorescence method to measure net capillary-to-airspace water transport. To measure the osmotic water permeability across the microvascular endothelial barrier in intact lung, the airspace was filled with a water-immiscible fluorocarbon. The capillaries were perfused via the pulmonary artery with solutions of specified osmolalites containing a high-molecular-weight fluorescent dextran. An increase in perfusate osmolality produced a prompt decrease in surface fluorescence due to dye dilution in the capillaries, followed by a slower return to initial fluorescence as capillary and lung interstitial osmolality equilibrate. A mathematical model was developed to determine the osmotic water permeability coefficient (Pf) of lung microvessels from the time course of pleural surface fluorescence. As predicted, the magnitude of the prompt change in surface fluorescence increased with decreased pulmonary artery perfusion rate and increased osmotic gradient size. With raffinose used to induce the osmotic gradient, Pf was 0.03 cm/s at 23 degrees C and was reduced 54% by 0.5 mM HgCl2. Temperature dependence measurements gave an Arrhenius activation energy (Ea) of 5.4 kcal/mol (12-37 degrees C). The apparent Pf induced by the smaller osmolytes mannitol and glycine was 0.021 and 0.011 cm/s (23 degrees C). Immunoblot analysis showed approximately 1.4 x 10(12) aquaporin-1 water channels/cm2 of capillary surface, which accounted quantitatively for the high Pf. These results establish a novel method for measuring osmotically driven water permeability across microvessels in intact lung. The high Pf, low Ea, and mercurial inhibition indicate the involvement of molecular water channels in water transport across the lung endothelium. PMID:9545071

  8. Partially pyrolyzed olive pomace sorbent of high permeability for preconcentration of metals from environmental waters.

    PubMed

    El-Sheikh, Amjad H; Sweileh, Jamal A; Saleh, Maysoon I

    2009-09-30

    The aim of this work is to develop a preconcentration procedure of Cd(2+), Zn(2+) and Cu(2+) in environmental waters using olive pomace (OP) prior to their determination by flame atomic absorption spectrometry (FAAS). Raw OP as preconcentrating sorbent was found to have low permeability towards the passed water samples and thus long time was needed. Even reducing the vacuum pressure caused cartridge blockage. Novel preconcentrating sorbents of high permeability were then prepared by heat pretreatment under inert atmosphere (partial pyrolysis) of OP at various temperatures (100, 150, 200, 250 and 300 degrees C). The permeability of OP pyrolyzed at 200 degrees C (sorbent OP-200) was enhanced 11 times relative to the raw OP, which significantly reduced the time required in the preconcentration process. A preconcentration procedure was optimized using OP-200 as preconcentrating sorbent, in which the detection limits were 42 ng L(-1) for Cu(2+), 76 ng L(-1) for Zn(2+) and 172 ng mL(-1) for Cd(2+). The method was linear within the studied concentration range (2-100 ng mL(-1)). The proposed method gave recoveries from 83+/-6 to 103+/-5% for determination of metals in tap water; and recoveries from 81+/-6 to 100+/-6% in well water. The method was validated by comparison with independent method and by analysis of lake sediments LKSD-4 certified reference material.

  9. [Effects of 18β-glycyrrhetinic Acid on the Expression of CCL11, AQP1 and EOS in Nasal Mucosa of Allergic Rhinitis Rats].

    PubMed

    Li, Juan-li; Xi, Ke-hu; Hou, Yun; Jiang, Ying; Gui, Yan; Wang, You-hu; Zhang, Fu-hong; Zhang, Xiao-bing

    2015-05-01

    To investigate the effects of 18β-glycyrrhetinic acid (GA) on the expression of eotaxin 1 (CCL11), aquaporin protein 1 (AQP1) and eosinophil (EOS) in nasal mucosa of allergic rhinitis (AR) rats. Seventy six Wistar rats were randomly divided into 4 groups, normal control (NC) group, AR model (AR) group, loratadine (LOA) group and 18β-GA group. All the mice in AR, LOA and 18β-GA groups were sensitized intraperitoneally with OVA and AL(OH), from day 1-14, then induced by intranasal administration with OVA from day 14-21, while the mice in NC group were sensitized with saline. The mice in both LOA and 18β-GA group were given LOA and 18β-GA once a day respectively from the 21 d, while the mice in AR and NC groups were administrated with saline. At the end of 1 week, 2 weeks and 3 weeks, the behavioral changes of mice were observed and recorded, the level of CCL11 mRNA was measured by RT-QPCR, and AQP1 expression was investiaged by SP staing. EOS in nasal mucosa was studied with the methods of HE staining. Compared with NC group, AR group showed typical AR symptoms. With the treatments, AR symptom scores and the expression levels of CCL11, AQP1 and EOS in nasal mucosa were improved significantly (P<0. 05). When compared with AR group, the above statistics in LOA group were down-regulated evidently at different points in time (P<. 05). At the end of 1 week, the above detection results in 18β-GA group were lower than those in AR group (P<0. 05). At the end of 2 weeks, those parameters approached to the levels of LOA and NC group significantly. 18β-GA administration could down-regulate the expression levels of CCL11, AQP1 and EOS in nasal mucosa of allergic rhinitis rats and cast effects on inhibiting the progress of AR.

  10. Use of geophysical logs to estimate the quality of ground water and the permeability of aquifers

    USGS Publications Warehouse

    Hudson, J.D.

    1996-01-01

    The relation of formation factor to resistivity of formation water and intergranular permeability has often been investigated, and the general consensus is that this relation is closest when established in a clean-sand aquifer in which water quality does not vary substantially. When these restrictions are applied, the following standard equation is a useful tool in estimating the resistance of the formation water: F = Ro/Rw, where F is the formation factor, which is a function of the effective porosity; Ro is the resistivity of a formation that is 100 percent saturated with interstitial water; and Rw is the resistivity of the water in the saturated zone. However, arenaceous aquifers can have electrical resistivities that are not directly related to resistivity of water or porosity. Surface conductivity and ion exchange are significant factors when the sediments are clay bearing. The solid constituents are a major component of the parameters needed to solve the equation for formation-water resistivity and estimates of aquifer permeability. A correction process needs to be applied to adjust the variables, Ro and F, to the equivalent of clean sand. This report presents an empirical method of using the neutron log and the electrical-resistivity values from long- and short-normal resistivity logs to correct for fine-grained material and the subsequent effects of low impedance to electrical flow that are not related to the resistance of formation water.

  11. The water channel aquaporin-1 contributes to renin cell recruitment during chronic stimulation of renin production.

    PubMed

    Tinning, Anne R; Jensen, Boye L; Schweda, Frank; Machura, Katharina; Hansen, Pernille B L; Stubbe, Jane; Gramsbergen, Jan Bert; Madsen, Kirsten

    2014-12-01

    Both the processing and release of secretory granules involve water movement across granule membranes. It was hypothesized that the water channel aquaporin (AQP)1 directly contributes to the recruitment of renin-positive cells in the afferent arteriole. AQP1(-/-) and AQP1(+/+) mice were fed a low-salt (LS) diet [0.004% (wt/wt) NaCl] for 7 days and given enalapril [angiotensin-converting enzyme inhibitor (ACEI), 0.1 mg/ml] in drinking water for 3 days. There were no differences in plasma renin concentration at baseline. After LS-ACEI, plasma renin concentrations increased markedly in both genotypes but was significantly lower in AQP1(-/-) mice compared with AQP1(+/+) mice. Tissue renin concentrations were higher in AQP1(-/-) mice, and renin mRNA levels were not different between genotypes. Mean arterial blood pressure was not different at baseline and during LS diet but decreased significantly in both genotypes after the addition of ACEI; the response was faster in AQP1(-/-) mice but then stabilized at a similar level. Renin release after 200 μl blood withdrawal was not different. Isoprenaline-stimulated renin release from isolated perfused kidneys did not differ between genotypes. Cortical tissue norepinephrine concentrations were lower after LS-ACEI compared with baseline with no difference between genotypes. Plasma nitrite/nitrate concentrations were unaffected by genotype and LS-ACEI. In AQP1(-/-) mice, the number of afferent arterioles with recruitment was significantly lower compared with AQP1(+/+) mice after LS-ACEI. We conclude that AQP1 is not necessary for acutely stimulated renin secretion in vivo and from isolated perfused kidneys, whereas recruitment of renin-positive cells in response to chronic stimulation is attenuated or delayed in AQP1(-/-) mice.

  12. Enthalpic Effects of Chain Length and Unsaturation on Water Permeability across Droplet Bilayers of Homologous Monoglycerides.

    PubMed

    Lopez, Maria; Evangelista, Sue Ellen; Morales, Melissa; Lee, Sunghee

    2017-01-31

    A deeper understanding of unassisted passive transport processes can better delineate basic lipid dynamics in biological membranes. A droplet interface bilayer (DIB) is made by contacting two aqueous droplets covered with a lipid monolayer, and has increasingly been employed as a model artificial biological membrane. In this study, we have investigated the effect of acyl chain structure of amphiphilic monoglycerides on the osmotic permeability of water across DIB membranes composed of these monoglycerides, where the acyl chain length (C14-C24), number of double bonds (1-4), and the position of double bond are varied systematically along the acyl chains. Both permeability values and activation energies have been extracted for water transport across a lipid bilayer formed of a homologous series of lipids, allowing us to make ready comparisons between the different lipids and potentially better elucidate the contributions that molecular motifs make to the permeation process.

  13. Gelation, swelling and water vapor permeability behavior of radiation synthesized poly(ethylene oxide) hydrogels

    NASA Astrophysics Data System (ADS)

    Savaş, Hülya; Güven, Olgun

    2002-04-01

    In this study, gamma ray induced gelation of aqueous solutions of poly(ethylene oxide), (PEO) with 73.300 Da average molecular weight has been studied. Percent of conversion of polymer into gel as well as swelling behavior were investigated gravimetrically. The effect of the dose rate on these properties was studied. Within the dose rate range studied, it is observed that low dose rate irradiation favors chain scission and although the dominant effect is still crosslinking, %gelation at a given dose decreases. Water vapor permeability (Wvp) of PEO hydrogels has been studied with regard to crosslink density changes and temperature. The water vapor permeability of hydrogels obtained at high dose rate was found to be lower than those obtained at low dose rate which was related to higher crosslink density achieved under higher dose rate irradiations.

  14. Water permeability and mechanical properties of unsaturated lipid membranes and sarcolemmal vesicles

    NASA Astrophysics Data System (ADS)

    Olbrich, Kevin Caddell

    The purpose of this investigation was to determine the: (1) mechanical and failure properties of unsaturated lipid membranes, (2) water permeability of unsaturated lipid membranes, and (3) mechanical properties and contribution of the water channel AQP4 to the water permeability of sarcolemmal vesicles. The micropipet technique was used to determine the mechanical properties and water permeability of individual vesicles composed of unsaturated lipids. The lipids used were: stearoyloleoylphosphatidylcholine (18:0/1), oleoylstearoylphosphatdiylcholine (18:1/0), dioleoylphosphatidylcholine ((d18:1c9), dielaidoylphosphatidylcholine (d18:1t9), dipetroselinoylphosphatidylcholine (d18:1c6), stearoyllinoylphosphatidylcholine (18:0/2), and dilinoylphosphatidylcholine (d18:2). The area expansion moduli of the unsaturated lipids were within 10% of the mean value of 198-mN/m, regardless of the degree of unsaturation. The presence of one or more linoyl chains decreased the lysis tension from {˜}7-mN/m to {˜}4-mN/m. The presence of unsaturation in the 6-position (d18:1c6) increased the lysis tension to 9.6-mN/m. The area expansion modulus of sarcolemmal vesicles was 346-mN/m, similar to that for synthetic vesicles composed of a mixture of 18:0/1 and 30% cholesterol (323-mN/m). The area expansion modulus of the pure lipids did not vary with temperature. The area expansion modulus of the sarcolemmal vesicles and the lipid/cholesterol mixture decreased with temperature at the rate of 5.2-mN msp{-1}\\ sp° Csp{-1} and 2.4-mN msp{-1}\\ sp° Csp{-1}, respectively. The lysis tension of unsaturated lipids decreased (non-linearly) with temperature. The water permeability of unsaturated lipid vesicles increased with degree of unsaturation and temperature from 19.6-μm/sec in 18:0/1 at 15sp° C to 101.6-μm/sec in d18:2 at 25sp° C. Positioning the unsaturation in the 6-position and substituting transconformation double bonds decreased the water permeability from 46-μm/sec at 21sp° C

  15. Experimental Study on the Strength Characteristics and Water Permeability of Hybrid Steel Fibre Reinforced Concrete.

    PubMed

    Singh, M P; Singh, S P; Singh, A P

    2014-01-01

    Results of an investigation conducted to study the effect of fibre hybridization on the strength characteristics such as compressive strength, split tensile strength, and water permeability of steel fibre reinforced concrete (SFRC) are presented. Steel fibres of different lengths, that is, 12.5 mm, 25 mm, and 50 mm, having constant diameter of 0.6 mm, were systematically combined in different mix proportions to obtain mono, binary, and ternary combinations at each of 0.5%, 1.0%, and 1.5% fibre volume fraction. A concrete mix containing no fibres was also cast for reference purpose. A total number of 1440 cube specimens of size 100∗100∗100 mm were tested, 480 each for compressive strength, split tensile strength, and water permeability at 7, 28, 90, and 120 days of curing. It has been observed from the results of this investigation that a fibre combination of 33% 12.5 mm + 33% 25 mm + 33% 50 mm long fibres can be adjudged as the most appropriate combination to be employed in hybrid steel fibre reinforced concrete (HySFRC) for optimum performance in terms of compressive strength, split tensile strength and water permeability requirements taken together.

  16. Experimental Study on the Strength Characteristics and Water Permeability of Hybrid Steel Fibre Reinforced Concrete

    PubMed Central

    Singh, M. P.; Singh, S. P.; Singh, A. P.

    2014-01-01

    Results of an investigation conducted to study the effect of fibre hybridization on the strength characteristics such as compressive strength, split tensile strength, and water permeability of steel fibre reinforced concrete (SFRC) are presented. Steel fibres of different lengths, that is, 12.5 mm, 25 mm, and 50 mm, having constant diameter of 0.6 mm, were systematically combined in different mix proportions to obtain mono, binary, and ternary combinations at each of 0.5%, 1.0%, and 1.5% fibre volume fraction. A concrete mix containing no fibres was also cast for reference purpose. A total number of 1440 cube specimens of size 100∗100∗100 mm were tested, 480 each for compressive strength, split tensile strength, and water permeability at 7, 28, 90, and 120 days of curing. It has been observed from the results of this investigation that a fibre combination of 33% 12.5 mm + 33% 25 mm + 33% 50 mm long fibres can be adjudged as the most appropriate combination to be employed in hybrid steel fibre reinforced concrete (HySFRC) for optimum performance in terms of compressive strength, split tensile strength and water permeability requirements taken together. PMID:27379298

  17. Temporal evolution modeling of hydraulic and water quality performance of permeable pavements

    NASA Astrophysics Data System (ADS)

    Huang, Jian; He, Jianxun; Valeo, Caterina; Chu, Angus

    2016-02-01

    A mathematical model for predicting hydraulic and water quality performance in both the short- and long-term is proposed based on field measurements for three types of permeable pavements: porous asphalt (PA), porous concrete (PC), and permeable inter-locking concrete pavers (PICP). The model was applied to three field-scale test sites in Calgary, Alberta, Canada. The model performance was assessed in terms of hydraulic parameters including time to peak, peak flow and water balance and a water quality variable (the removal rate of total suspended solids). A total of 20 simulated storm events were used for model calibration and verification processes. The proposed model can simulate the outflow hydrographs with a coefficient of determination (R2) ranging from 0.762 to 0.907, and normalized root-mean-square deviation (NRMSD) ranging from 13.78% to 17.83%. Comparison of the time to peak flow, peak flow, runoff volume and TSS removal rates between the measured and modeled values in model verification phase had a maximum difference of 11%. The results demonstrate that the proposed model is capable of capturing the temporal dynamics of the pavement performance. Therefore, the model has great potential as a practical modeling tool for permeable pavement design and performance assessment.

  18. Chemical Composition and Water Permeability of Fruit and Leaf Cuticles of Olea europaea L.

    PubMed

    Huang, Hua; Burghardt, Markus; Schuster, Ann-Christin; Leide, Jana; Lara, Isabel; Riederer, Markus

    2017-09-07

    The plant cuticle, protecting against uncontrolled water loss, covers olive (Olea europaea) fruits and leaves. The present study describes the organ-specific chemical composition of the cuticular waxes and the cutin and compares three developmental stages of fruits (green, turning and black) with the leaf surface. Numerous organ-specific differences, such as the total coverage of cutin monomeric components (1034.4 µg cm(-2) and 630.5 µg cm(-2)) and the cuticular waxes (201.6 µg cm(-2) and 320.4 µg cm(-2)) among all three fruit stages and leaves, respectively, were detected. Water permeability as the main cuticular function was five-fold lower in adaxial leaf cuticles (2.1 x 10-5 m s(-1)) in comparison to all three fruit stages (9.5 x 10-5 m s(-1)). The three fruit developmental stages have the same cuticular water permeability. It is hypothesized that a higher weighted average chain length of the acyclic cuticular components leads to a considerably lower permeability of the leaf as compared to the fruit cuticle.

  19. The Water to Solute Permeability Ratio Governs the Osmotic Volume Dynamics in Beetroot Vacuoles

    PubMed Central

    Vitali, Victoria; Sutka, Moira; Amodeo, Gabriela; Chara, Osvaldo; Ozu, Marcelo

    2016-01-01

    Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (Pf) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, Pf determinations are made in vitro from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated Beta vulgaris root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast Pf. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (Pf/Ps), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements

  20. The Water to Solute Permeability Ratio Governs the Osmotic Volume Dynamics in Beetroot Vacuoles.

    PubMed

    Vitali, Victoria; Sutka, Moira; Amodeo, Gabriela; Chara, Osvaldo; Ozu, Marcelo

    2016-01-01

    Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (Pf ) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, Pf determinations are made in vitro from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated Beta vulgaris root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast Pf . We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (Pf /Ps ), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements

  1. Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins.

    PubMed

    Tunuguntla, Ramya H; Henley, Robert Y; Yao, Yun-Chiao; Pham, Tuan Anh; Wanunu, Meni; Noy, Aleksandr

    2017-08-25

    Fast water transport through carbon nanotube pores has raised the possibility to use them in the next generation of water treatment technologies. We report that water permeability in 0.8-nanometer-diameter carbon nanotube porins (CNTPs), which confine water down to a single-file chain, exceeds that of biological water transporters and of wider CNT pores by an order of magnitude. Intermolecular hydrogen-bond rearrangement, required for entry into the nanotube, dominates the energy barrier and can be manipulated to enhance water transport rates. CNTPs block anion transport, even at salinities that exceed seawater levels, and their ion selectivity can be tuned to configure them into switchable ionic diodes. These properties make CNTPs a promising material for developing membrane separation technologies. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  2. Membrane permeability of the human granulocyte to water, dimethyl sulfoxide, glycerol, propylene glycol and ethylene glycol.

    PubMed

    Vian, Alex M; Higgins, Adam Z

    2014-02-01

    Granulocytes are currently transfused as soon as possible after collection because they rapidly deteriorate after being removed from the body. This short shelf life complicates the logistics of granulocyte collection, banking, and safety testing. Cryopreservation has the potential to significantly increase shelf life; however, cryopreservation of granulocytes has proven to be difficult. In this study, we investigate the membrane permeability properties of human granulocytes, with the ultimate goal of using membrane transport modeling to facilitate development of improved cryopreservation methods. We first measured the equilibrium volume of human granulocytes in a range of hypo- and hypertonic solutions and fit the resulting data using a Boyle-van't Hoff model. This yielded an isotonic cell volume of 378 μm(3) and an osmotically inactive volume of 165 μm(3). To determine the permeability of the granulocyte membrane to water and cryoprotectant (CPA), cells were injected into well-mixed CPA solution while collecting volume measurements using a Coulter Counter. These experiments were performed at temperatures ranging from 4 to 37°C for exposure to dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol. The best-fit water permeability was similar in the presence of all of the CPAs, with an average value at 21°C of 0.18 μmatm(-1)min(-1). The activation energy for water transport ranged from 41 to 61 kJ/mol. The CPA permeability at 21°C was 6.4, 1.0, 8.4, and 4.0 μm/min for dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol, respectively, and the activation energy for CPA transport ranged between 59 and 68 kJ/mol.

  3. Difference in expression between AQP1 and AQP5 in porcine endometrium and myometrium in response to steroid hormones, oxytocin, arachidonic acid, forskolin and cAMP during the mid-luteal phase of the estrous cycle and luteolysis.

    PubMed

    Skowronska, Agnieszka; Mlotkowska, Patrycja; Nielsen, Soren; Skowronski, Mariusz T

    2015-12-01

    Recently, we demonstrated in vitro that AQP1 and AQP5 in the porcine uterus are regulated by steroid hormones (P4, E2), arachidonic acid (AA), forskolin (FSK) and cAMP during the estrous cycle. However, the potential of the porcine separated uterine tissues, the endometrium and myometrium, to express these AQPs remains unknown. Thus, in this study, the responses of AQP1 and AQP5 to P4, E2 oxytocin (OT), AA, FSK and cAMP in the porcine endometrium and myometrium were examined during the mid-luteal phase of the estrous cycle and luteolysis. Real-time PCR and western blot analysis. Progesterone up-regulated the expression of AQP1/AQP5 mRNAs and proteins in the endometrium and myometrium, especially during luteolysis. Similarly, E2 also stimulated the expression of both AQPs, but only in the endometrium. AA led to the upregulation of AQP1/AQP5 in the endometrium during luteolysis. In turn, OT increased the expression of AQP1/AQP5 mRNAs and proteins in the myometrium during mid-luteal phase. Moreover, a stimulatory effect of forskolin and cAMP on the expression of AQP1/AQP5 mRNAs and proteins in the endometrium and myometrium dominated during luteolysis, but during the mid-luteal phase their influence on the expression of these AQPs was differentiated depending on the type of tissue and the incubation duration. These results seem to indicate that uterine tissues; endometrium and myometrium, exhibit their own AQP expression profiles in response to examined factors. Moreover, the responses of AQP1/AQP5 at mRNA and protein levels to the studied factors in the endometrium and myometrium are more pronounced during luteolysis. This suggests that the above effects of the studied factors are connected with morphological and physiological changes taking place in the pig uterus during the estrous cycle.

  4. Osmotic water transport in aquaporins: evidence for a stochastic mechanism

    PubMed Central

    Zeuthen, Thomas; Alsterfjord, Magnus; Beitz, Eric; MacAulay, Nanna

    2013-01-01

    We test a novel, stochastic model of osmotic water transport in aquaporins. A solute molecule present at the pore mouth can either be reflected or permeate the pore. We assume that only reflected solute molecules induce osmotic transport of water through the pore, while permeating solute molecules give rise to no water transport. Accordingly, the rate of water transport is proportional to the reflection coefficient σ, while the solute permeability, PS, is proportional to 1 –σ. The model was tested in aquaporins heterologously expressed in Xenopus oocytes. A variety of aquaporin channel sizes and geometries were obtained with the two aquaporins AQP1 and AQP9 and mutant versions of these. Osmotic water transport was generated by adding 20 mm of a range of different-sized osmolytes to the outer solution. The osmotic water permeability and the reflection coefficient were measured optically at high resolution and compared to the solute permeability obtained from short-term uptake of radio-labelled solute under isotonic conditions. For each type of aquaporin there was a linear relationship between solute permeability and reflection coefficient, in accordance with the model. We found no evidence for coupling between water and solute fluxes in the pore. In confirmation of molecular dynamic simulations, we conclude that the magnitude of the osmotic water permeability and the reflection coefficient are determined by processes at the arginine selectivity filter located at the outward-facing end of the pore. PMID:23959676

  5. Effects of karst and geologic structure on the circulation of water and permeability in carbonate aquifers

    USGS Publications Warehouse

    Stringfield, V.T.; Rapp, J.R.; Anders, R.B.

    1979-01-01

    The results of the natural processes caused by solution and leaching of limestone, dolomite, gypsum, salt and other soluble rocks, is known as karst. Development of karst is commonly known as karstification, which may have a pronounced effect on the topography, hydrology and environment, especially where such karst features as sinkholes and vertical solution shafts extend below the land surface and intersect lateral solution passages, cavities, caverns and other karst features in carbonate rocks. Karst features may be divided into two groups: (1) surficial features that do not extend far below the surface; and (2) karst features such as sinkholes that extend below the surface and affect the circulation of water below. The permeability of the most productive carbonate aquifers is due chiefly to enlargement of fractures and other openings by circulation of water. Important controlling factors responsible for the development of karst and permeability in carbonate aquifers include: (1) climate, topography, and presence of soluble rocks; (2) geologic structure; (3) nature of underground circulation; and (4) base level. Another important factor is the condition of the surface of the carbonate rocks at the time they are exposed to meteoric water. A carbonate rock surface, with soil or relatively permeable, less soluble cover, is more favorable for initiation of karstification and solution than bare rocks. Water percolates downward through the cover to the underlying carbonate rocks instead of running off on the surface. Also, the water becomes more corrosive as it percolates through the permeable cover to the underlying carbonate rocks. Where there is no cover or the cover has been removed, the carbonate rocks become case hardened and resistant to erosion. However, in regions underlain not only by carbonate rocks but also by beds of anhydrite, gypsum and salt, such as the Hueco Plateau in southeastern New Mexico, subsurface solution may occur where water without natural

  6. The water channel aquaporin-1a1 facilitates movement of CO₂ and ammonia in zebrafish (Danio rerio) larvae.

    PubMed

    Talbot, Krystle; Kwong, Raymond W M; Gilmour, Kathleen M; Perry, Steve F

    2015-12-01

    The present study tested the hypothesis that zebrafish (Danio rerio) aquaporin-1a1 (AQP1a1) serves as a multi-functional channel for the transfer of the small gaseous molecules, CO2 and ammonia, as well as water, across biological membranes. Zebrafish embryos were microinjected with a translation-blocking morpholino oligonucleotide targeted to AQP1a1. Knockdown of AQP1a1 significantly reduced rates of CO2 and ammonia excretion, as well as water fluxes, in larvae at 4 days post fertilization (dpf). Because AQP1a1 is expressed both in ionocytes present on the body surface and in red blood cells, the haemolytic agent phenylhydrazine was used to distinguish between the contributions of AQP1a1 to gas transfer in these two locations. Phenylhydrazine treatment had no effect on AQP1a1-linked excretion of CO2 or ammonia, providing evidence that AQP1a1 localized to the yolk sac epithelium, rather than red blood cell AQP1a1, is the major site of CO2 and ammonia movements. The possibility that AQP1a1 and the rhesus glycoprotein Rhcg1, which also serves as a dual CO2 and ammonia channel, act in concert to facilitate CO2 and ammonia excretion was explored. Although knockdown of each protein did not affect the abundance of mRNA and protein of the other protein under control conditions, impairment of ammonia excretion by chronic exposure to high external ammonia triggered a significant increase in the abundance of AQP1a1 mRNA and protein in 4 dpf larvae experiencing Rhcg1 knockdown. Collectively, these results suggest that AQP1a1 in zebrafish larvae facilitates the movement of CO2 and ammonia, as well as water, in a physiologically relevant fashion.

  7. Long-Term Groundwater Monitoring Optimization, Clare Water Supply Superfund Site, Permeable Reactive Barrier and Soil Remedy Areas, Clare, Michigan

    EPA Pesticide Factsheets

    This report contains a review of the long-term groundwater monitoring network for the Permeable Reactive Barrier (PRB) and Soil Remedy Areas at the Clare Water Supply Superfund Site in Clare, Michigan.

  8. Regulation of water permeability in rabbit conjunctival epithelium by anisotonic conditions.

    PubMed

    Candia, Oscar A; Alvarez, Lawrence J; Zamudio, Aldo C

    2006-04-01

    Effects of unilateral exposure to anisotonic conditions on diffusional water permeability of the isolated rabbit conjunctiva were determined. A segment of the bulbar-palpebral conjunctiva was mounted between Ussing-type hemichambers under short-circuit conditions. Unidirectional water fluxes (J(dw)) were measured in either direction by adding (3)H(2)O to one hemichamber and sampling from the other. Electrical parameters were measured simultaneously. J(dw) were determined under control isosmotic conditions and after introduction of either hyper- or hypotonic solutions against the tear or stromal sides of the preparations. In each of these four separate conditions, the anisotonic medium produced an approximately 20-30% reduction in J(dw) across the tissue, with the exception that to obtain such reduction with increased tonicity from the stromal side (medium osmolality increased by adding sucrose), conditions presumptively inhibiting regulatory volume increase mechanisms (e.g., pretreatment with amiloride and bumetanide) were also required. All reductions in J(dw) elicited by the various anisotonic conditions were reversible on restoration of control tonicity. In experiments in which preparations were pretreated with the protein cross-linking agent glutaraldehyde, anisotonicity-elicited reductions in J(dw) were not observed. Such reductions were also not observed in the presence of HgCl(2), implying the involvement of aquaporins. However, it is possible that the mercurial may be toxic to the epithelium, preventing the tonicity response. Nevertheless, from concomitant changes in transepithelial electrical resistance, as well as [(14)C]mannitol fluxes, [(14)C]butanol fluxes, and Arrhenius plots, arguments are presented that the above effects are best explained as a cell-regulated reduction in membrane water permeability that occurs at the level of water-transporting channels. Presumably both apical and basolateral membranes can downregulate their water permeabilities as

  9. Interfacial nanobubbles are leaky: permeability of the gas/water interface.

    PubMed

    German, Sean R; Wu, Xi; An, Hongjie; Craig, Vincent S J; Mega, Tony L; Zhang, Xuehua

    2014-06-24

    Currently there is no widespread agreement on an explanation for the stability of surface nanobubbles. One means by which several explanations can be differentiated is through the predictions they make about the degree of permeability of the gas-solution interface. Here we test the hypothesis that the gas-solution interface of surface nanobubbles is permeable by experimental measurements of the exchange of carbon dioxide. We present measurements by attenuated total reflection Fourier transform infrared (ATR-FTIR) and atomic force microscopy (AFM), demonstrating that the gas inside surface nanobubbles is not sealed inside the bubbles, but rather exchanges with the dissolved gas in the liquid phase. Such gas transfer is measurable by using the infrared active gas CO2. We find that bubbles formed in air-saturated water that is then perfused with CO2-saturated water give rise to distinctive gaseous CO2 signals in ATR-FTIR measurements. Also the CO2 gas inside nanobubbles quickly dissolves into the surrounding air-saturated water. AFM images before and after fluid exchange show that CO2 bubbles shrink upon exposure to air-equilibrated liquid but remain stable for hours. Also air bubbles in contact with CO2-saturated water increase in size and Ostwald ripening occurs more rapidly due to the relatively high gas solubility of CO2 in water.

  10. Short-term control of maize cell and root water permeability through plasma membrane aquaporin isoforms.

    PubMed

    Hachez, Charles; Veselov, Dmitry; Ye, Qing; Reinhardt, Hagen; Knipfer, Thorsten; Fricke, Wieland; Chaumont, François

    2012-01-01

    Although it is widely accepted that aquaporins are involved in the regulation of root water uptake, the role of specific isoforms in this process is poorly understood. The mRNA expression and protein level of specific plasma membrane intrinsic proteins (PIPs) were analysed in Zea mays in relation to cell and root hydraulic conductivity. Plants were analysed during the day/night period, under different growth conditions (aeroponics/hydroponics) and in response to short-term osmotic stress applied through polyethylene glycol (PEG). Higher protein levels of ZmPIP1;2, ZmPIP2;1/2;2, ZmPIP2;5 and ZmPIP2;6 during the day coincided with a higher water permeability of root cortex cells during the day compared with night period. Similarly, plants which were grown under aeroponic conditions and which developed a hypodermis ('exodermis') with Casparian bands, effectively forcing more water along a membranous uptake path across roots, showed increased levels of ZmPIP2;5 and ZmPIP1;2 in the rhizodermis and exodermis. When PEG was added to the root medium (2-8 h), expression of PIPs and cell water permeability in roots increased. These data support a role of specific PIP isoforms, in particular ZmPIP1;2 and ZmPIP2;5, in regulating root water uptake and cortex cell hydraulic conductivity in maize.

  11. Preliminary permeability and water-retention data for nonwelded and bedded tuff samples, Yucca Mountain area, Nye County, Nevada

    SciTech Connect

    Flint, L.E.; Flint, A.L.

    1990-12-31

    Measurements of rock-matrix hydrologic properties at Yucca Mountain, a potential site for a high-level nuclear waste repository, are needed to predict rates and direction of water flow in the unsaturated zone. The objective of this study is to provide preliminary data on intrinsic and relative permeability and moisture retention on rock core samples and to present the methods used to collect these data. Four methods were used to measure intrinsic, or saturated permeability: Air, Klinkenberg, specific permeability to oil, and specific permeability to water. Two methods yielded data on relative permeability (gas-drive and centrifuge), and three methods (porous plate, centrifuge, and mercury intrusion porosimetry) were used to measure water-retention properties (matric potential compared to water-content curves). Standard measurements of grain density, bulk density, and porosity for the core samples were included. Results of this study showed a large range of intrinsic permeability values among rock types and high variability within rock types. The four methods yield intrinsic permeability values that are different but are highly correlated (coefficient of determination greater than 0.94). 27 refs., 3 figs., 11 tabs.

  12. Temperature influences on water permeability and chlorpyrifos uptake in aquatic insects with differing respiratory strategies

    USGS Publications Warehouse

    Buchwalter, D.B.; Jenkins, J.J.; Curtis, L.R.

    2003-01-01

    Aquatic insects have evolved diverse respiratory strategies that range from breathing atmospheric air to breathing dissolved oxygen. These strategies result in vast morphological differences among taxa in terms of exchange epithelial surface areas that are in direct contact with the surrounding water that, in turn, affect physiological processes. This paper examines the effects of acute temperature shifts on water permeability and chlorpyrifos uptake in aquatic insects with different respiratory strategies. While considerable differences existed in water permeability among the species tested, acute temperature shifts raised water influx rates similarly in air-breathing and gill-bearing taxa. This contrasts significantly with temperature-shift effects on chlorpyrifos uptake. Temperature shifts of 4.5??C increased 14C-chlorpyrifos accumulation rates in the gill-bearing mayfly Cinygma sp. and in the air-breathing hemipteran Sigara washingtonensis. However, the temperature-induced increase in 14C-chlorpyrifos uptake after 8 h of exposure was 2.75-fold higher in Cinygma than in Sigara. Uptake of 14C-chlorpyrifos was uniformly higher in Cinygma than in Sigara in all experiments. These findings suggest that organisms with relatively large exchange epithelial surface areas are potentially more vulnerable to both osmoregulatory distress as well as contaminant accumulation. Temperature increases appear more likely to impact organisms that have relatively large exchange epithelial surface areas, both as an individual stressor and in combination with additional stressors such as contaminants.

  13. Cholesterol effect on water permeability through DPPC and PSM lipid bilayers: a molecular dynamics study.

    PubMed

    Saito, Hiroaki; Shinoda, Wataru

    2011-12-29

    Water permeability of two different lipid bilayers of dipalmitoylphosphatidylcholine (DPPC) and palmitoylsphingomyelin (PSM) in the absence and presence of cholesterol (0-50 mol %) have been studied by molecular dynamics simulations to elucidate the molecular mechanism of the reduction in water leakage across the membranes by the addition of cholesterol. An enhanced free energy barrier was observed in these membranes with increased cholesterol concentration, and this was explained by the reduced cavity density around the cholesterol in the hydrophobic membrane core. There was an increase of trans conformers in the hydrophobic lipid chains adjacent to the cholesterol, which reduced the cavity density. The enhanced free energy barrier was found to be the main reason to reduce the water permeability with increased cholesterol concentration. At low cholesterol concentrations the PSM bilayer exhibited a higher free energy barrier than the DPPC bilayer for water permeation, while at greater than 30 mol % of cholesterol the difference became minor. This tendency for the PSM and DPPC bilayers to resemble each other at higher cholesterol concentrations was similar to commonly observed trends in several structural properties, such as order parameters, cross-sectional area per molecule, and cavity density profiles in the hydrophobic regions of bilayer membranes. These results demonstrate that DPPC and PSM bilayers with high cholesterol contents possess similar physical properties, which suggests that the solubility of cholesterol in these lipid bilayers has importance for an understanding of multicomponent lipid membranes with cholesterol.

  14. A dual-permeability approach to preferential water flow and solute transport in shrinking soils

    NASA Astrophysics Data System (ADS)

    Coppola, Antonio; dragonetti, giovanna; Comegna, Alessandro; Gerke, Horst H.; Basile, Angelo

    2016-04-01

    The pore systems in most natural soils is dynamically changing due to alternating swelling and shrinkage processes, which induces changes in pore volume and pore size distribution including deformations in pore geometry. This is a serious difficulty for modeling flow and transport in dual permeability approaches, as it will also require that the geometrical deformation of both the soil matrix and the fracture porous systems be taken into account, as well as the dynamics of soil hydraulic properties in response to the domain deformations. This study follows up a previous work by the same authors extending the classical rigid (RGD) approach formerly proposed by Gerke and van Genuchten, to account for shrinking effects (SHR) in modeling water flow and solute transport in dual-permeability porous media. In this study we considered three SHR scenarios, assuming that aggregate shrinkage may change either: (i) the hydraulic properties of the two pore domains, (ii) their relative fractions, and (iii) both, hydraulic properties and fractions of the two domains. The objective was to compare simulation results obtained under the RGD and the SHR assumptions to illustrate the impact of matrix volume changes on water storage, water fluxes and solute concentrations during: 1) An infiltration process bringing an initially dry soil to saturation, 2) A drainage process starting from an initially saturated soil. For an infiltration process, the simulated wetting front and the solute concentration propagation velocity, as well as the water fluxes, water and solute exchange rates, for the three SHR scenarios significantly deviated from the RGD. By contrast, relatively similar water content profiles evolved under all scenarios during drying. Overall, compared to the RGD approach, the effect of changing the hydraulic properties and the weight of the two domains according to the shrinkage behavior of the soil aggregates induced a much more rapid response in terms of water fluxes and

  15. Modeling reactive transport of reclaimed water through large soil columns with different low-permeability layers

    NASA Astrophysics Data System (ADS)

    Hu, Haizhu; Mao, Xiaomin; Barry, D. A.; Liu, Chengcheng; Li, Pengxiang

    2015-03-01

    The efficacy of different proportions of silt-loam/bentonite mixtures overlying a vadose zone in controlling solute leaching to groundwater was quantified. Laboratory experiments were carried out using three large soil columns, each packed with 200-cm-thick riverbed soil covered by a 2-cm-thick bentonite/silt-loam mixture as the low-permeability layer (with bentonite mass accounting for 12, 16 and 19 % of the total mass of the mixture). Reclaimed water containing ammonium (NH4 +), nitrate (NO3 -), organic matter (OM), various types of phosphorus and other inorganic salts was applied as inflow. A one-dimensional mobile-immobile multi-species reactive transport model was used to predict the preferential flow and transport of typical pollutants through the soil columns. The simulated results show that the model is able to predict the solute transport in such conditions. Increasing the amount of bentonite in the low-permeability layer improves the removal of NH4 + and total phosphorous (TP) because of the longer contact time and increased adsorption capacity. The removal of NH4 + and OM is mainly attributed to adsorption and biodegradation. The increase of TP and NO3 - concentration mainly results from discharge and nitrification in riverbed soils, respectively. This study underscores the role of low-permeability layers as barriers in groundwater protection. Neglect of fingers or preferential flow may cause underestimation of pollution risk.

  16. Dexmedetomidine alleviates pulmonary edema by upregulating AQP1 and AQP5 expression in rats with acute lung injury induced by lipopolysaccharide.

    PubMed

    Jiang, Yuan-xu; Dai, Zhong-liang; Zhang, Xue-ping; Zhao, Wei; Huang, Qiang; Gao, Li-kun

    2015-10-01

    This study aims to elucidate the mechanisms by which dexmedetomidine alleviates pulmonary edema in rats with acute lung injury induced by lipopolysaccharide (LPS). Male Wistar rats were randomly divided into five groups: normal saline control (NS) group, receiving intravenous 0.9% normal saline (5 mL/kg); LPS group, receiving intravenous LPS (10 mg/kg); small-dose dexmedetomidine (S) group, treated with a small dose of dexmedetomidine (0.5 μg · kg(-1) · h(-1)); medium-dose dexmedetomidine (M) group, treated with a medium dose of dexmedetomidine (2.5 μg · kg(-1) · h(-1)); high-dose dexmedetomidine (H) group, treated with a high dose of dexmedetomidine (5 μg · kg(-1) · h(-1)). The rats were sacrificed 6 h after intravenous injection of LPS or NS, and the lungs were removed for evaluating histological characteristics and determining the lung wet/dry weight ratio (W/D). The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) in the lung tissues were assessed by enzyme- linked immunosorbent assay (ELISA). The mRNA and protein expression levels of aquaporin-1 (AQP1) and aquaporin-5 (AQP5) were detected by RT-PCR, immunohistochemistry, and Western blotting. The lung tissues from the LPS groups were significantly damaged, which were less pronounced in the H group but not in the small-dose dexmedetomidine group or medium-dose dexmedetomidine group. The W/D and the concentrations of TNF-α and IL-1β in the pulmonary tissues were increased in the LPS group as compared with those in NS group, which were reduced in the H group but not in S group or M group (P<0.01). The expression of AQP1 and AQP5 was lower in the LPS group than in the NS group, and significantly increased in the H group but not in the S group or M group (P<0.01). Our findings suggest that dexmedetomidine may alleviate pulmonary edema by increasing the expression of AQP-1 and AQP-5.

  17. Development of an evaporation-optimized and water-permeable pavement

    NASA Astrophysics Data System (ADS)

    Starke, P.; Göbel, P.; Coldewey, W. G.

    2009-04-01

    During recent decades, urban areas have been threatened more frequently by flood events. Furthermore, the potential for damage from these events has increased on average. The construction of houses, streets and parking lots has caused this trend by sealing the ground surface, i.e. these water-impermeable areas reduce the natural infiltration and evaporation-rates, and in some cases it is even completely stopped. The consequence is the so called "urban water cycle". Water from precipitation cannot be stored anywhere and so there is an immediate and very high surface run-off effect. Especially after intense rain events, canalisations and sewage-treatment plants are overloaded and this leads to higher costs for water treatment and to environmental damage. A practical solution to this problem is the use of water-permeable pavements. Here higher infiltration rates lead to a groundwater recharge that is greater than that of natural soils. The consequences from using these surfaces are already noticeable in many places through increasing groundwater levels. These increases cause damage to buildings. A second difference from a natural-soil water-balance is a lower evapotranspiration rate. Up to now the evaporation rates for water-permeable pavements has not been established accurately. The aim of the applied research project at the University of Muenster, which is sponsored by the DBU (The German Federal Environmental Foundation), is to gain knowledge of urban evaporation rates and of water-permeable surfaces, especially water-permeable pavements. Water-permeable pavements consist of the paving stone surface and the two sub-base layers below. Pre-investigations show that evaporation can be influenced by the complete sub-base. Therefore, the first step was to investigate which materials are used for sub-base construction. All in all, 27 materials were collected from throughout Germany and these materials were then tested (in terms of physical and hydraulic attributes) in

  18. Permeability enhancement due to cold water injection: A Case Study at the Los Azufres Geothermal Field, Mexico

    SciTech Connect

    Benson, S.M.; Daggett, J.; Ortiz, J.; Iglesias, E.; Comision Federal de Electricidad, Morelia; Instituto de Investigaciones Electricas, Cuernavaca )

    1989-04-01

    Pressure transient buildup and falloff data from 3 wells at the Los Azufres geothermal field have been evaluated to determine the extent to which cold water infection increases the permeability of the near-bore reservoir formation. Simultaneous analysis of the buildup and falloff data provides estimates of the permeability-thickness of the reservoir, the skin factor of the well, and the degree of permeability enhancement in the region behind the thermal front. Estimates of permeability enhancement range from a factor of 4 to 9, for a temperature change of about 150{degree}C. The permeability enhancement is attributed to thermally induced contraction and stress-cracking of the formation. 9 refs., 18 figs.

  19. D184E mutation in aquaporin-4 gene impairs water permeability and links to deafness.

    PubMed

    Nicchia, G P; Ficarella, R; Rossi, A; Giangreco, I; Nicolotti, O; Carotti, A; Pisani, F; Estivill, X; Gasparini, P; Svelto, M; Frigeri, A

    2011-12-01

    Aquaporins (AQPs) play a physiological role in several organs and tissues, and their alteration is associated with disorders of water regulation. The identification of molecular interactions, which are crucial in determining the rate of water flux through the channel, is of pivotal role for the discovery of molecules able to target those interactions and therefore to be used for pathologies ascribable to an altered AQP-dependent water balance. In the present study, a mutational screening of human aquaporin-4 (AQP4) gene was performed on subjects with variable degrees of hearing loss. One heterozygous missense mutation was identified in a Spanish sporadic case, leading to an Asp/Glu amino acid substitution at position 184 (D184E). A BLAST analysis revealed that the amino acid D184 is conserved across species, consistently with a crucial role in the structure/function of AQP4 water channels. The mutation induces a significant reduction in water permeability as measured by the Xenopus laevis oocytes swelling assay and by the use of mammalian cells by total internal reflection microscopy. By Western blot, immunofluorescence and 2D Blue Native/SDS-PAGE we show that the reduction in water permeability is not ascribable to a reduced expression of AQP4 mutant protein or to its incorrect plasma membrane targeting and aggregation into orthogonal arrays of particles. Molecular dynamics simulation provided a molecular explanation of the mechanism whereby the mutation induces a loss of function of the channel. Substituting glutamate for aspartate affects the mobility of the D loop, which acquires a higher propensity to equilibrate in a "closed conformation", thus affecting the rate of water flux. We speculate that this mutation, combined with other genetic defects or concurrently with certain environmental stimuli, could confer a higher susceptibility to deafness.

  20. Fabrication of monodisperse hollow silica spheres and effect on water vapor permeability of polyacrylate membrane.

    PubMed

    Bao, Yan; Yang, Yongqiang; Ma, Jianzhong

    2013-10-01

    Polystyrene/silica core-shell spheres were fabricated using polystyrene as templates by hydrolysis and condensation of tetraethyl orthosilicate through a sol-gel process, in which polystyrene was synthesized by emulsion polymerization. Then, hollow silica spheres were obtained after selective removal of the organic polystyrene core from the polystyrene/silica core-shell spheres by tetrahydrofuran etching. The effect of hollow silica spheres on water vapor permeability, mechanical property, and water uptake of polyacrylate membrane were investigated. The microstructure analysis shows that the mean size and wall thickness of hollow silica spheres are 170 nm and 20 nm, respectively. The silica shells consist of amorphous silica seed assembly with a broad size distribution, which roughen the surfaces of hollow silica spheres greatly. The specific surface area of hollow silica spheres is bigger than that of polystyrene/silica core-shell spheres. Hollow silica spheres can significantly improve water vapor permeability of polyacrylate membrane, but lead to the reduction in mechanical property.

  1. Extravascular lung water and the pulmonary vascular permeability index may improve the definition of ARDS.

    PubMed

    Perel, Azriel

    2013-01-24

    The recent Berlin definition has made some improvements in the older definition of acute respiratory distress syndrome (ARDS), although the concepts and components of the definition remained largely unchanged. In an effort to improve both predictive and face validity, the Berlin panel has examined a number of additional measures that may reflect increased pulmonary vascular permeability, including extravascular lung water. The panel concluded that although extravascular lung water has improved face validity and higher values are associated with mortality, it is infeasible to mandate on the basis of availability and the fact that it does not distinguish between hydrostatic and inflammatory pulmonary edema. However, the results of a multi-institutional study that appeared in the previous issue of Critical Care show that this latter reservation may not necessarily be true. By using extravascular lung water and the pulmonary vascular permeability index, both of which are derived from transpulmonary thermodilution, the authors could successfully differentiate between patients with ARDS and other patients in respiratory failure due to either cardiogenic edema or pleural effusion with atelectasis. This commentary discusses the merits and limitations of this study in view of the potential improvement that transpulmonary thermodilution may bring to the definition of ARDS.

  2. Cationic sulfonium functionalization renders Znsalens with high fluorescence, good water solubility and tunable cell-permeability.

    PubMed

    Tang, Juan; Xie, Da; Yin, Hao-Yan; Jing, Jing; Zhang, Jun-Long

    2016-04-07

    In this study, we report for the first time that incorporation of cationic sulfonium to the Znsalens skeleton achieves water soluble fluorescent metal complex probes for living cell imaging. To circumvent Znsalen aggregation arising from intermolecular ZnO interactions (found between Zn and the phenoxyl group of another Znsalen molecule), we synthesized a series of sulfonium Znsalens based on alkylation of the 3-thioether or 3,5-dithioether moieties of salicylaldehydes. Such functionalization not only provides positive charge(s) to enhance electrostatic repulsion, but also increases steric hindrance, which renders the Znsalen complex water soluble as a monomeric species in aqueous media as revealed by diffusion ordered NMR spectroscopy (DOSY). More interestingly, these sulfonium Znsalens display "switched on" fluorescence when compared to thioether analogues, which was attributed to the electron-withdrawing sulfonium moiety that perturbs the photoinduced electron transfer (PET) process as suggested by computational calculations based on time-dependent density functional theory (TD-DFT). Most interestingly, live cell imaging experiments showed that modulation of the sulfonium moieties, such as the number or alkyl substituents, significantly tunes the cell-permeability of the fluorescent Znsalens. Thus, this study has demonstrated the importance of sulfonium functionalization on dissociating the intermolecular metal-ligand interactions and thus, modulating water solubility, photophysical properties and even cell-permeability of the fluorophores, which provides a new approach to the design of functional metal complexes for biological studies.

  3. Coupled Hydrogeophysical Inversion for Characterizing Heterogeneous Permeability Field at a Groundwater-River Water Interaction Zone

    NASA Astrophysics Data System (ADS)

    Chen, X.; Johnson, T. C.; Hammond, G. E.; Zachara, J. M.

    2014-12-01

    The hydrological and biogeochemical processes at the groundwater and river water interface are largely controlled by the exchange dynamics between the two water bodies. Accurate characterization of the heterogeneous permeability field at such interface is critical for modeling the bulk flow as well as the biogeochemical processes that are coupled with the flow. Taking advantage of the distinct conductivities in groundwater and rive water, time lapse electrical resistivity tomography (ERT) can provide rich spatial and temporal data for characterizing the permeability field, by imaging the change in subsurface electric conductivity driven by river water intrusion and retreat. We installed a large-scale (300 m by 300 m) 3-dimensional ERT array to monitor river water intrusion and retreat through time at a major river corridor, and the 4-dimensional electrical geophysical data is assimilated to invert for the underlying permeability field using ensemble-based algorithms (e.g., ensemble Kalman filter and ensemble smoother). We developed a new high-performance hydrogeophysical code by coupling an ERT imaging code E4D (Johnson et al., 2010) with a site-scale flow and transport code, PFLOTRAN (Hammond et al., 2012). The coupled code provides the key modeling capability of multi-physics processes, parallel efficiency, and multi-realization simulation capability for hydrogeophysical inversion. We assimilated both well-based point measurements of water table and specific conductance and spatially continuous ERT images in a sequential Bayesian way. Our study demonstrates the effectiveness of joint hydrogeophysical inversion for large-scale characterization of subsurface properties in the groundwater and river water interaction zone. Our investigation of spatial versus temporal data assimilation strategies have inspired systematic data worth analyses to identify the most valuable data sets for hydrogeophysical inversion. The high performance computing is performed on the Hopper

  4. Toward high permeability, selectivity and controllability of water desalination with FePc nanopores.

    PubMed

    Deng, Qingming; Pan, Jun; Yin, Xiaohui; Wang, Xiaofeng; Zhao, Lina; Kang, Seung-gu; Jimenez-Cruz, Camilo A; Zhou, Ruhong; Li, Jingyuan

    2016-03-21

    Nanoporous materials exhibit promising potential in water transportation applications, especially in ocean water desalination. It is highly desired to have great permeability, selectivity and controllability in the desalination performance of these nanopores. However, it is still a challenge to achieve all three features in one material or device. Here, we demonstrate efficient and controllable water desalination with a nanoporous 2D Fe phthalocyanine (FePc) membrane using molecular dynamics simulations. We find the FePc membrane not only conducts fast water flow, but it also suppresses ion permeation. The selectivity is attributed to a mechanism distinct from the traditional steric exclusion: cations are excluded due to electrostatic repulsion, whereas anions can be trapped in the nanopore and induce the reorganization of ions in the vicinity of the nanopore, which in turn creates a tendency for the trapped anions to move back into the saline reservoir. More interestingly, we find such mechanism is largely due to the sufficiently strong electrostatic interaction of the charged nanopore region with ions and is not restricted to the FePc nanopore. In addition, the number of protonated nitrogen atoms in FePc pores can be modulated by adjusting the pH value of the solution. The extent of the anion occupancy can thus be regulated, giving rise to control of the water flow. Taken together, great permeability, selectivity and controllability can be achieved with this nanosheet system. Moreover, our study suggests there is an alternative mechanism of water desalination which may be realized by intrinsically nanoporous materials such as FePc membranes.

  5. Human Oocyte Vitrification: The permeability of metaphase II oocytes to water and ethylene glycol and the appliance toward vitrification

    PubMed Central

    Mullen, Steven F.; Li, Mei; Li, Yuan; Chen, Zi-Jiang; Critser, John K.

    2008-01-01

    Objectives To determine the permeability of human metaphase II oocytes to ethylene glycol and water in the presence of ethylene glycol, and to use this information to develop a method to vitrify human oocytes. Design An incomplete randomized block design was used for this study. Setting A University-affiliated assisted reproductive center. Patients Women undergoing assisted reproduction in the Center for Reproductive Medicine at Shandong University. Interventions Oocytes were exposed to 1.0 molar ethylene glycol in a single step, and photographed during subsequent volume excursions. Main outcome measures A 2-parameter model was employed to estimate the permeability to water and EG. Results Water permeability ranged from 0.15 to 1.17 µm/(min·atm), and ethylene glycol permeability ranged from 1.5 to 30 µm/min between 7 °C at 36 °C. The activation energies for water and ethylene glycol permeability were 14.42 Kcal/mol and 21.20 Kcal/mol, respectively. Conclusions Despite the lower permeability of human MII oocytes to ethylene glycol compared to previously published values for propylene glycol and dimethylsulfoxide, methods to add and remove human oocytes with a vitrifiable concentration of ethylene glycol can be designed which prevent excessive osmotic stress and minimize exposure to high concentrations of this compound. PMID:17681308

  6. Permeability and expansibility of natural bentonite MX-80 in distilled water

    NASA Astrophysics Data System (ADS)

    Liu, Longcheng; Neretnieks, Ivars; Moreno, Luis

    Natural bentonite MX-80 differs from the purified and fully Na-exchanged bentonite in that it contains approximately 20.0% accessory minerals, in addition to the montmorillonite particles. Since the accessory minerals and montmorillonite particles have very different physical and chemical properties, natural bentonite MX-80 is found to expand much more slowly in distilled water, leading actually to a three-component system that has very different hydraulic properties from that of the fully Na-exchanged bentonite. To better understand and simulate the special features of expansion of natural bentonite MX-80 in distilled water, the focus is put primarily on the development of a Kozeny-Carman-like equation for its hydraulic permeability in the same way as it was done for Na-exchanged bentonite. With this permeability model, the dynamic force balance model that was originally developed for colloidal expansion of montmorillonite in a two-component system is applied to the natural MX-80 system. Without making any changes to the model, however, two strategies are used to account for both physical and chemical effects of the accessory minerals. The “lumped” strategy assumes that the accessory minerals are stuck onto the montmorillonite particles in such a way that they behave just like one solid component. The “stepwise” strategy changes the pore water chemistry gradually from initially distilled water to eventually achievement of the equilibrium condition. These strategies are simple but proved to function well. The agreement between the simulations and the experimental results indicates that the two-component dynamic force balance model works well in predicting the general features and the behavior of upward expansion of natural bentonite MX-80 in distilled water in a vertical test tube.

  7. The dynamic placenta: II. Hypothetical model of a fetus driven transplacental water balance mechanism producing low apparent permeability in a highly permeable placenta.

    PubMed

    Sebire, N J; Talbert, D

    2004-01-01

    In vitro and isotopic studies in vivo have reported the paradox that the human placenta is highly permeable, water exchanging at 3.6 litres per hour at 35 weeks of gestation, but clinical measurements in vivo show net transfer is minimal, around 2 ml/day. Current theories are based on osmotic pressure balances, but changes in maternofetal hydrostatic pressure change much faster than osmotic factors could respond. An alternative explanation might be that net transfer is not in fact the result of passive mechanisms, but is actively controlled by the fetus itself. The fetus is well equipped to monitor changes in blood volume, such as via sensors in venous and atrial stretch receptors to control ANF and hence urine production. Transplacental water regulation requires modification of transvillus pressures. Placental sub-chorial arteries and veins (of extra-embryonic origin) have different sensitivities from fetal body tissues to some vasoactive substances, and stem villous veins have unusually well developed vascular smooth muscle. It is thus theoretically possible for the fetus to modify subchorial venous resistances, and hence villous capillary pressure with a suitable circulating placental venous constrictive agent. A computer modelling study was undertaken using a fictitious placental venous constricting agent "fictensin", considered to be released by the fetus in proportion to disturbance of vascular volume. The effective placental permeability fell in proportion to the tightness of this fetal control mechanism, suggesting that the apparent placental permeability measured in vivo is a measure of fetal control, not true permeability. However, the range of compensatory pressures that the fetus can produce by this means is limited and failure of such a mechanism could allow flooding or dehydration of the feto-placental unit. This may shed new light on disorders such as polyhydramnios and fetal hydrops.

  8. Self-assembled hydrophobin for producing water-soluble and membrane permeable fluorescent dye.

    PubMed

    Wang, Kunpeng; Xiao, Yunjie; Wang, Yanyan; Feng, Yaqing; Chen, Cheng; Zhang, Jie; Zhang, Qian; Meng, Shuxian; Wang, Zefang; Yang, Haitao

    2016-03-15

    Low water solubility and poor membrane permeability are major disadvantages that compromise applications of most fluorescent dyes. To resolve these problems, herein, using Boron-dipyrromethene (BODIPY) as a model fluorescent dye, for the first time, we provide a new strategy for the rapid and efficient production of a water-soluble and membrane-permeable dye by mixing with an amphiphilic protein named hydrophobin. Data shows BODIPY could be effectively solubilized and dispersed in 200 μg/mL hydrophobin by simple mixing and sonication. Subsequent experiments indicated that hydrophobin self-assembled into a protein film on the surface of BODIPY forming stable hydrophobin-BODIPY complexes with a size range of 10-30 nm. Furthermore, we demonstrated hydrophobin-functionalized BODIPY are toxicity free to cells. The hydrophobin-BODIPY complex could pass through both the cell plasma membrane and nuclear membrane efficiently. Our work opens a novel route to modify and functionalize fluorescent dyes and may be developed as a general strategy for broadening their applications.

  9. The Effect of Hypertonic Media on Water Permeability of Frog Urinary Bladder

    PubMed Central

    Ripoche, P.; Bourguet, J.; Parisi, M.

    1973-01-01

    The frog urinary bladder undergoes, in some conditions, a marked increase of its water permeability when incubated in hypertonic media. This increase was observed with various nonpermeant solutes. It seems to result from the shrinkage of an osmo-sensitive compartment of the tissue, probably the epithelial cells. Many similarities were found between this effect and the physiological increase in water permeability (hydrosmotic response) elicited by antidiuretic hormone (ADH): both were dependent on the physiological state of the animals, and although the response was slower after hyperosmolar than after hormonal challenge, the patterns of response were similar, and in both cases markedly dependent on bathing solution temperature. Norepinephrine and prostaglandin E1, which in this tissue reduce the hydrosmotic action of ADH, presumably by inhibiting the adenyl cylase also reduced the effect of hyperosmolarity. Conversely this effect was potentiated by incubation in the presence of oxytocin, exogenous cyclic AMP, and theophylline, conditions in which the intracellular concentration of cyclic AMP is increased. These data demonstrate that the response to hyperosmolarity is elicited, at least partly, by mechanisms also involved in the physiological hydrosmotic response to ADH. PMID:4345637

  10. Self-assembled hydrophobin for producing water-soluble and membrane permeable fluorescent dye

    PubMed Central

    Wang, Kunpeng; Xiao, Yunjie; Wang, Yanyan; Feng, Yaqing; Chen, Cheng; Zhang, Jie; Zhang, Qian; Meng, Shuxian; Wang, Zefang; Yang, Haitao

    2016-01-01

    Low water solubility and poor membrane permeability are major disadvantages that compromise applications of most fluorescent dyes. To resolve these problems, herein, using Boron-dipyrromethene (BODIPY) as a model fluorescent dye, for the first time, we provide a new strategy for the rapid and efficient production of a water-soluble and membrane-permeable dye by mixing with an amphiphilic protein named hydrophobin. Data shows BODIPY could be effectively solubilized and dispersed in 200 μg/mL hydrophobin by simple mixing and sonication. Subsequent experiments indicated that hydrophobin self-assembled into a protein film on the surface of BODIPY forming stable hydrophobin-BODIPY complexes with a size range of 10–30 nm. Furthermore, we demonstrated hydrophobin-functionalized BODIPY are toxicity free to cells. The hydrophobin-BODIPY complex could pass through both the cell plasma membrane and nuclear membrane efficiently. Our work opens a novel route to modify and functionalize fluorescent dyes and may be developed as a general strategy for broadening their applications. PMID:26976627

  11. Aquaporin water channels in the mammary gland: from physiology to pathophysiology and neoplasia.

    PubMed

    Mobasheri, Ali; Barrett-Jolley, Richard

    2014-03-01

    Aquaporins are membrane proteins that play fundamental roles in water and small solute transport across epithelial and endothelial barriers. Recent studies suggest that several aquaporin proteins are present in the mammary gland. Immunohistochemical techniques have confirmed the presence of aquaporin 1 (AQP1) and AQP3 water channels in rat, mouse, bovine and human mammary glands. Studies suggest that in addition to AQP1 and AQP3 AQP4, AQP5 and AQP7 proteins are expressed in different locations in the mammary gland. Aquaporins play key roles in tumor biology and are involved in cell growth, migration and formation of ascites via increased water permeability of micro-vessels. Emerging evidence suggests that expression of these proteins is altered in mammary tumors and in breast cancer cell lines although it is not yet clear whether this is a cause or a consequence of neoplastic development. This review analyzes the expression and potential functional roles of aquaporin water channels in the mammary gland. The physiological mechanisms involved in the transport of water and small solutes across mammary endothelial and epithelial barriers are discussed in the context of milk production and lactation. This paper also reviews papers from the recent cancer literature that implicate aquaporins in mammary neoplasia.

  12. Evaluating the relative air permeability of porous media from their water retention curves

    NASA Astrophysics Data System (ADS)

    Assouline, S.; Tuli, A.; Hopmans, J. W.

    2016-05-01

    Accurate modeling of water and air flow in porous media requires the definition of the relevant hydraulic properties, namely, the water retention curve (WRC) and the relative hydraulic conductivity function (RHC), as well as the definition of the relative air permeability function (RAP). Capitalizing on the approach developed previously to represent the RHC, a new model allowing the prediction of RAP based on information resulting from the WRC is proposed. The power value ηa in the model is a decreasing exponential function of the coefficient of variation, ɛ, characterizing the pore size distribution of the porous medium, and derived from its WRC. The model was calibrated using data from 22 disturbed and undisturbed soil samples and was validated using data from eight soil types ranging from quartz sand to silty clay loam. The proposed model provided accurate prediction of the soil RAP and performed in some cases (sandy loam and silty clay loam soils) better than available alternative models.

  13. Ground water remediation of chromium using zero-valent iron in a permeable reactive barrier

    SciTech Connect

    Puls, R.W.; Powell, R.M.; Paul, C.J.; Blowes, D.

    1998-09-01

    A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of iron and in systems with iron mixed with aquifer materials. Various geochemical parameters were measured to confirm the proposed reactions. Laboratory experiments were scaled up to pilot and full-scale field demonstrations. Intensive geochemical sampling in the field tests corroborate laboratory results and successfully demonstrate the effectiveness of this innovative in situ approach to remediate chromate-contaminated ground water using a permeable reactive barrier composed of zero-valent iron.

  14. Membrane-associated aquaporin-1 facilitates osmotically driven water flux across the basolateral membrane of the thick ascending limb

    PubMed Central

    Cabral, Pablo D.

    2012-01-01

    The thick ascending limb of the loop of Henle (TAL) reabsorbs ∼30% of filtered NaCl but is impermeable to water. The observation that little water traverses the TAL indicates an absence of water channels at the apical membrane. Yet TAL cells swell when peritubular osmolality decreases indicating that water channels must be present in the basolateral side. Consequently, we hypothesized that the water channel aquaporin-1 (AQP1) facilitates water flux across the basolateral membrane of TALs. Western blotting revealed AQP1 expression in microdissected rat and mouse TALs. Double immunofluorescence showed that 95 ± 2% of tubules positive for the TAL-specific marker Tamm-Horsfall protein were also positive for AQP1 (n = 6). RT-PCR was used to demonstrate presence of AQP1 mRNA and the TAL-specific marker NKCC2 in microdissected TALs. Cell surface biotinylation assays showed that 23 ± 3% of the total pool of AQP1 was present at the TAL basolateral membrane (n = 7). To assess the functional importance of AQP1 in the basolateral membrane, we measured the rate of cell swelling initiated by decreasing peritubular osmolality as an indicator of water flux in microdissected TALs. Water flux was decreased by ∼50% in Aqp1 knockout mice compared with wild-types (4.0 ± 0.8 vs. 8.9 ± 1.7 fluorescent U/s, P < 0.02; n = 7). Furthermore, arginine vasopressin increased TAL AQP1 expression by 135 ± 17% (glycosylated) and 41 ± 11% (nonglycosylated; P < 0.01; n =5). We conclude that 1) the TAL expresses AQP1, 2) ∼23% of the total pool of AQP1 is localized to the basolateral membrane, 3) AQP1 mediates a significant portion of basolateral water flux, and 4) AQP1 is upregulated in TALs of rats infused with dDAVP. AQP1 could play an important role in regulation of TAL cell volume during changes in interstitial osmolality, such as during a high-salt diet or water deprivation. PMID:22674028

  15. AqF026 Is a Pharmacologic Agonist of the Water Channel Aquaporin-1

    PubMed Central

    Morelle, Johann; Cnops, Yvette; Verbavatz, Jean-Marc; Campbell, Ewan M.; Beckett, Elizabeth A.H.; Booker, Grant W.; Flynn, Gary

    2013-01-01

    Aquaporin-1 (AQP1) facilitates the osmotic transport of water across the capillary endothelium, among other cell types, and thereby has a substantial role in ultrafiltration during peritoneal dialysis. At present, pharmacologic agents that enhance AQP1-mediated water transport, which would be expected to increase the efficiency of peritoneal dialysis, are not available. Here, we describe AqF026, an aquaporin agonist that is a chemical derivative of the arylsulfonamide compound furosemide. In the Xenopus laevis oocyte system, extracellular AqF026 potentiated the channel activity of human AQP1 by >20% but had no effect on channel activity of AQP4. We found that the intracellular binding site for AQP1 involves loop D, a region associated with channel gating. In a mouse model of peritoneal dialysis, AqF026 enhanced the osmotic transport of water across the peritoneal membrane but did not affect the osmotic gradient, the transport of small solutes, or the localization and expression of AQP1 on the plasma membrane. Furthermore, AqF026 did not potentiate water transport in Aqp1-null mice, suggesting that indirect mechanisms involving other channels or transporters were unlikely. Last, in a mouse gastric antrum preparation, AqF026 did not affect the Na-K-Cl cotransporter NKCC1. In summary, AqF026 directly and specifically potentiates AQP1-mediated water transport, suggesting that it deserves additional investigation for applications such as peritoneal dialysis or clinical situations associated with defective water handling. PMID:23744886

  16. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  17. Water Exposure is a Common Risk Behavior Among Soft and Gas-Permeable Contact Lens Wearers

    PubMed Central

    Richdale, Kathryn; Mitchell, Gladys Lynn; Kinoshita, Beth T.; Lam, Dawn Y.; Wagner, Heidi; Sorbara, Luigina; Chalmers, Robin L.; Collier, Sarah A.; Cope, Jennifer R.; Rao, Maya M.; Beach, Michael J.; Yoder, Jonathan S.

    2017-01-01

    Purpose: To understand soft contact lens (SCL) and gas-permeable (GP) lens wearers' behaviors and knowledge regarding exposure of lenses to water. Methods: The Contact Lens Risk Survey (CLRS) and health behavior questions were completed online by a convenience sample of 1056 SCL and 85 GP lens wearers aged 20 to 76 years. Participants were asked about exposing their lenses to water and their understanding of risks associated with these behaviors. Chi-square analyses examined relationships between patient behaviors and perceptions. Results: GP lens wearers were more likely than SCL wearers to ever rinse or store lenses in water (rinsing: 91% GP, 31% SCL, P < 0.001; storing: 33% GP, 15% SCL P < 0.001). Among SCL wearers, men were more likely to store (24% vs. 13%, P = 0.003) or rinse (41% vs. 29%, P = 0.012) their lenses in water. Showering while wearing lenses was more common in SCL wearers (86%) than GP lens wearers (67%) (P < 0.0001). Swimming while wearing lenses was reported by 62% of SCL wearers and 48% of GP lens wearers (P = 0.027). Wearers who rinsed (SCL; P < 0.0001, GP; P = 0.11) or stored lenses in water (SCL; P < 0.0001, GP P = 0.007) reported that this behavior had little or no effect on their infection risk, compared with those who did not. Both SCL (P < 0.0001) and GP lens wearers (P < 0.0001) perceived that distilled water was safer than tap water for storing or rinsing lenses. Conclusions: Despite previously published evidence of Acanthamoeba keratitis' association with water exposure, most SCL, and nearly all GP lens wearers, regularly expose their lenses to water, with many unaware of the risk. PMID:28410356

  18. Regulation of Macrophage Motility by the Water Channel Aquaporin-1: Crucial Role of M0/M2 Phenotype Switch

    PubMed Central

    Tyteca, Donatienne; Nishino, Tomoya; Debaix, Huguette; Van Der Smissen, Patrick; N'Kuli, Francisca; Hoffmann, Delia; Cnops, Yvette; Rabolli, Virginie; van Loo, Geert; Beyaert, Rudi; Huaux, François; Devuyst, Olivier; Courtoy, Pierre J.

    2015-01-01

    The water channel aquaporin-1 (AQP1) promotes migration of many cell types. Although AQP1 is expressed in macrophages, its potential role in macrophage motility, particularly in relation with phenotype polarization, remains unknown. We here addressed these issues in peritoneal macrophages isolated from AQP1-deficient mice, either undifferentiated (M0) or stimulated with LPS to orientate towards pro-inflammatory phenotype (classical macrophage activation; M1). In non-stimulated macrophages, ablation of AQP1 (like inhibition by HgCl2) increased by 2–3 fold spontaneous migration in a Src/PI3K/Rac-dependent manner. This correlated with cell elongation and formation of lamellipodia/ruffles, resulting in membrane lipid and F4/80 recruitment to the leading edge. This indicated that AQP1 normally suppresses migration of resting macrophages, as opposed to other cell types. Resting Aqp1-/- macrophages exhibited CD206 redistribution into ruffles and increased arginase activity like IL4/IL13 (alternative macrophage activation; M2), indicating a M0-M2 shift. In contrast, upon M1 orientation by LPS in vitro or peritoneal inflammation in vivo, migration of Aqp1-/- macrophages was reduced. Taken together, these data indicate that AQP1 oppositely regulates macrophage migration, depending on stimulation or not by LPS, and that macrophage phenotypic and migratory changes may be regulated independently of external cues. PMID:25719758

  19. Aquaporin 6 is permeable to glycerol and urea.

    PubMed

    Holm, Lars M; Klaerke, Dan A; Zeuthen, Thomas

    2004-05-01

    The passive water permeability ( L(p)) of AQP6 is activated by Hg(2+). Our aim was to test if L(p) was associated with a permeability to small hydrophilic molecules such as glycerol and urea. AQP6 was expressed in Xenopus laevis oocytes and activated by 0.3 mM of HgCl(2) in the bathing solution. HgCl(2) caused the oocytes to swell at a rate of about 0.3% min(-1). The L(p) of AQP6 was determined from brief additions or removals of mannitol from the bathing solution, and compared to the L(p) obtained from adding glycerol or urea. In paired experiments, L(p (mannitol)) was 2.4+/-0.1, L(p (glycerol)) 1.5+/-0.2, and L(p (urea)) 0.7+/-0.1 (units: 10(-5) cm s(-1) osmol(-1); 14 oocytes); the latter was not different from L(p)s obtained for native oocytes. The L(p)s were independent of the Hg(2+)-induced swelling and of the magnitude of the osmotic challenge (-75 to +100 mosmol). Hg(2+) stimulated the uptake of [(14)C]glycerol fivefold and [(14)C]urea twofold in AQP6-expressing oocytes. There were no significant uptakes in native oocytes nor in AQP1-expressing oocytes whether these were treated with HgCl(2) or not. We conclude that water, glycerol and urea share an aqueous pathway in AQP6.

  20. Effect of dDAVP on basolateral cell surface water permeability in the outer medullary collecting duct.

    PubMed

    Solenov, E I; Nesterov, V V; Baturina, G S; Khodus, G R; Ivanova, L N

    2003-11-01

    We report a novel approach for assessing the volume of living cells which allows quantitative, high-resolution characterization of dynamic changes in cell volume while retaining the cell functionality. The aim of this study was to evaluate the short-term effect of vasopressin on basolateral cell surface water permeability in the outer medullary collecting duct (OMCD). The permeability of the basolateral cell membrane was determined in the tubules where the apical membrane was blocked with oil injected into the lumen. The apparent coefficient of water permeability (Pf) was evaluated by measuring the cell swelling after the step from hypertonic to isotonic medium (600 mosm to 300 mosm). Desmopressin (dDAVP) induced an increase of the basolateral Pf from 113.7+/-8.5 microm/s in control cells to 186.6+/-11.4 mum/s in micro-dissected fragments of the OMCD incubated in vitro (10(-7) M dDAVP, 30 min at 37 degrees C) (P<0.05). Mercury caused pronounced inhibition of basolateral water permeability (26.0+/-6.9 microm/s; P<0.05). The effect of mercury (1.0 mM HgCl2) was reversible: after washing the fragments with PBS for 20 min, Pf values were restored to the control levels (125.0+/-9.5 microm/s). The results of the study indicate the existence of a mechanism controlling the osmotic water permeability of the basolateral cell membrane in the OMCD epithelium.

  1. Potassium Deficiency-induced Changes in Stomatal Behavior, Leaf Water Potentials, and Root System Permeability in Beta vulgaris L. 1

    PubMed Central

    Graham, R. D.; Ulrich, Albert

    1972-01-01

    Studies of the water relations of potassium deficient sugarbeet plants (Beta vulgaris L.) revealed two factors for stomatal closure. One component of stomatal closure was reversible by floating leaf discs on distilled water to relieve the water deficit in the leaves; the other component was reversible in the light by floating the leaf discs on KCl solution for 1 hour or more. Potassium-activated stomatal opening in the light was observed when the guard cells were surrounded by their normal environment of epidermal and mesophyll cells, just as observed by previous workers for epidermal strips. Leaf water potentials, like stomatal apertures, appear to be strongly related to leaf potassium concentration. Potassium-deficient plants have a greatly decreased root permeability to water, and the implications of this effect on stomatal aperture and leaf water potential are discussed. In contrast, petiole permeability to water is unaffected by potassium treatment. PMID:16657905

  2. Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor

    SciTech Connect

    Couture, R.A.

    1984-01-01

    Packed columns of canister packing material containing 25% bentonite and 75% quartz or basalt sand, were exposed to water vapor at temperatures up t 260/sup 0/C. The permeabilities of the columns were subsequently measured after complete saturation with liquid water in a pressurized system. Exposure to water vapor caused irreversible increases in permeability by factors of up to 10/sup 5/. After saturation with liquid water, the permeability was nearly independent of temperature. The increases in permeability were due to a large decrease in the ability of the bentonite to swell in water. Calculations suggest that swelling of bentonite altered at 250/sup 0/C was not sufficient to fill the pore spaces. If the pore spaces are filled, the mixture will form an effective barrier against flow, diffusion, and transport of colloids. The results suggest that if bentonite-based canister packing material is exposed even briefly to water vapor at high temperatures in a high-level nuclear waste repository, its performance will be seriously impaired. The problem is less severe if the proportion of bentonite is high and the material is highly compacted. Previous results show significant degradation of bentonite by water vapor at temperatures as low as 150/sup 0/C. This suggests that in some repositories, backfill in tunnels and drifts may also be affected. 9 references, 5 figures, 1 table.

  3. Effects of testosterone on mean arterial pressure and aquaporin (AQP)-1, 2, 3, 4, 6 and 7 expressions in the kidney of orchidectomized, adult male Sprague-Dawley rats.

    PubMed

    Loh, Su Yi; Giribabu, Nelli; Gholami, Khadijeh; Salleh, Naguib

    2017-01-15

    We hypothesized that higher blood pressure in males than females could be due to testosterone effects on aquaporin (AQP) expression in kidneys. Orchidectomized adult male Sprague-Dawley (SD) rats received seven days subcutaneous testosterone treatment (125 μg/kg/day or 250 μg/kg/day), with or without flutamide or finasteride. Following completion of treatment, MAP was determined in rats under anaesthesia via carotid artery cannulation. In another cohort of rats, kidneys were removed following sacrifice and AQP-1, 2, 3, 4, 6 and 7 protein and mRNA levels were determined by Western blotting and Real-time PCR respectively. Distribution of AQP subunits' protein in the nephrons were visualized by immunofluorescence. Testosterone caused MAP, AQP-1, 2, 4, 6 and 7 protein and mRNA levels in kidneys to increase while AQP-3 protein and mRNA levels in kidneys to decrease (p < 0.05). AQP-1 and 7 were found to be distributed in the proximal convoluted tubule (PCT) while AQP-2, 3, 4 and 6 were found to be distributed in the collecting ducts (CD). Effects of testosterone were antagonized by flutamide and finasteride. Elevated expression of AQP-1, 2, 4, 6 and 7 under testosterone influence in kidneys could lead to increase H2O reabsorption which eventually lead to increase in blood pressure. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Classification of cassava starch films by physicochemical properties and water vapor permeability quantification by FTIR and PLS.

    PubMed

    Henrique, C M; Teófilo, R F; Sabino, L; Ferreira, M M C; Cereda, M P

    2007-05-01

    Cassava starches are widely used in the production of biodegradable films, but their resistance to humidity migration is very low. In this work, commercial cassava starch films were studied and classified according to their physicochemical properties. A nondestructive method for water vapor permeability determination, which combines with infrared spectroscopy and multivariate calibration, is also presented. The following commercial cassava starches were studied: pregelatinized (amidomax 3550), carboxymethylated starch (CMA) of low and high viscosities, and esterified starches. To make the films, 2 different starch concentrations were evaluated, consisting of water suspensions with 3% and 5% starch. The filmogenic solutions were dried and characterized for their thickness, grammage, water vapor permeability, water activity, tensile strength (deformation force), water solubility, and puncture strength (deformation). The minimum thicknesses were 0.5 to 0.6 mm in pregelatinized starch films. The results were treated by means of the following chemometric methods: principal component analysis (PCA) and partial least squares (PLS) regression. PCA analysis on the physicochemical properties of the films showed that the differences in concentration of the dried material (3% and 5% starch) and also in the type of starch modification were mainly related to the following properties: permeability, solubility, and thickness. IR spectra collected in the region of 4000 to 600 cm(-1) were used to build a PLS model with good predictive power for water vapor permeability determination, with mean relative errors of 10.0% for cross-validation and 7.8% for the prediction set.

  5. Effects of anionic surfactants on the water permeability of a model stratum corneum lipid membrane.

    PubMed

    Lee, Sang-Wook; Tettey, Kwadwo E; Yarovoy, Yury; Lee, Daeyeon

    2014-01-14

    The stratum corneum (SC) is the ourtermost layer of the epidermis and has a brick-and-mortar-like structure, in which multilamellar lipid bilayers surround flattened dead cells known as corneocytes. The SC lipid membranes provide the main pathway for the transport of water and other substances through the SC. While the physicochemical properties of the SC can be affected by exogenous materials such as surfactants, little is known about how the water barrier function of the SC lipid membranes is compromised by common surfactants. Here, we study the effect of common anionic surfactants on the water permeability of a model SC lipid membrane using a quartz crystal microbalance with dissipation monitoring (QCM-D). Particularly, the effect of sodium dodecyl sulfate (SDS) and sodium lauryl ether sulfate (SLES) is compared. These two surfactants share commonality in their molecular structure: sulfate in the polar headgroup and the same apolar tail. The mass of the lipid membranes increases after the surfactant treatment at or above the critical micelle concentration (CMC) of the surfactants due to their absorption into the membranes. The incorporation of the surfactants into the lipid membranes is also accompanied by partial dissolution of the lipids from the model SC lipid membranes as confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Although the water sorption of pure SDS is much lower than that of pure SLES, the water sorption of SDS-treated membranes increases significantly similar to that of SLES-treated membranes. By combining QCM-D and FT-IR spectroscopy, we find that the chain conformational order and stiffness of the lipid membranes decrease after SDS treatment, resulting in the increased water sorption and diffusivity. In contrast, the conformational order and stiffness of the SLES-treated lipid membranes increase, suggesting that the increased water sorption capacity of SLES-treated lipid membranes is due to the hygroscopic nature of SLES.

  6. Water permeability through biological membranes by isotopic effects of fluorescence and light scattering.

    PubMed Central

    Lawaczeck, R

    1984-01-01

    A light-scattering technique used to measure the water permeability across closed biomembranes is described, which is based on the different indices of refraction of D2O and H2O. This transient technique is compared with a similar method using D2O-sensitive fluorophores in the intravesicular space. The results of both techniques are equivalent although the signal-to-noise ratio favors the light-scattering or turbidity experiment. The light-scattering method is only applicable to larger particles (no point-scatterers) and is easily extended to biological objects. Data on the H2O/D2O exchange across membranes of ghosts from human erythrocytes suggest two mechanisms: the D2O and H2O permeation through the membrane and a slower D2O-induced conformational change of membraneous proteins. PMID:6546887

  7. A Systematic Comparison of Tidally Induced Water Pressure Changes with a Standard Aquifer Test to Infer Permeability

    NASA Astrophysics Data System (ADS)

    Allègre, V.; Brodsky, E. E.; Nale, S. M.; Johnson, N. M.

    2014-12-01

    The use of water level oscillations driven by earth tides is a technique which has been used to infer rock properties such as permeability and storage at the field scale. The tidal method is attractive because it provides passively estimated permeability time series, allows identification of dynamic changes over time, and measures a hard to access scale ranging from a meters to tens of meters. It consists of computing the phase shift between tidally induced water level changes measured in boreholes, and theoretical earth tide strains. This leads to an estimate of the transmissivity, from which permeability can be deduced. To our knowledge, it has not been compared to standard method, such as pumping test analysis.In this work, water level data monitored before, during, and after two constant rate pumping tests performed in a shallow fractured aquifer were used, at the Santa Susana Field Site in Southern California. The two tests were one to five months long, the recordings lasting approximately 6 months. Tidal frequency oscillations appearing in the measurements were used to get permeability at thirteen locations, some of the wells providing several isolated open screened intervals at depth. As a comparison, permeabilities were also estimated from the fit of two aquifer tests at both early and late stages, using Theis solution (Gringarten solution gives similar results). The simple Theis solution is selected because it includes assumptions consistent with the assumptions in the isotropic and homogeneous tidal solution. The values obtained from both methods are consistent. No significant relation between permeability and faults located in the vicinity of the wells was identified, however, we do observe some variations at depth. Furthermore, some variability is observed in permeability time series during the pumping phases. This study shows that tidal responses lead to a passive and accurate capture of the shallow aquifer properties.

  8. Effect of ethanol on the water permeability of controlled release films composed of ethyl cellulose and hydroxypropyl cellulose.

    PubMed

    Larsson, Mikael; Hjärtstam, Johan; Berndtsson, Jolina; Stading, Mats; Larsson, Anette

    2010-11-01

    The robustness of controlled release formulations when co-ingested with alcohol is a current concern expressed by regulatory authorities, especially with regard to dose dumping. One such controlled release formulation commonly used is film coating composed of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC). The aim of this study was to investigate how the presence of ethanol in the dissolution medium affects the water permeability of such films. Film samples were prepared in various EC-HPC compositions, and the effect of different ethanol concentrations in the dissolution medium on the permeability was studied using a modified Ussing chamber and tritiated water. It was found that the effect of ethanol on the film permeability varied depending on the composition of the films. The results were interpreted in terms of swelling of the EC in the films, where the swelling increased with increasing ethanol concentration. Thus, for films with low HPC content (non-interconnected pores), the water permeability of the films increased with increasing ethanol concentration as the diffusion through the ethyl cellulose increased due to swelling. However, for films with higher HPC content (having interconnected pores through the films), the permeability decreased, likely due to the swelling of the ethyl cellulose blocking the pores. The interpretation of the results was supported by dynamic mechanic analysis and SEM analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering.

    PubMed

    Vikingsson, L; Claessens, B; Gómez-Tejedor, J A; Gallego Ferrer, G; Gómez Ribelles, J L

    2015-08-01

    In tissue engineering the design and optimization of biodegradable polymeric scaffolds with a 3D-structure is an important field. The porous scaffold provide the cells with an adequate biomechanical environment that allows mechanotransduction signals for cell differentiation and the scaffolds also protect the cells from initial compressive loading. The scaffold have interconnected macro-pores that host the cells and newly formed tissue, while the pore walls should be micro-porous to transport nutrients and waste products. Polycaprolactone (PCL) scaffolds with a double micro- and macro-pore architecture have been proposed for cartilage regeneration. This work explores the influence of the micro-porosity of the pore walls on water permeability and scaffold compliance. A Poly(Vinyl Alcohol) with tailored mechanical properties has been used to simulate the growing cartilage tissue inside the scaffold pores. Unconfined and confined compression tests were performed to characterize both the water permeability and the mechanical response of scaffolds with varying size of micro-porosity while volume fraction of the macro-pores remains constant. The stress relaxation tests show that the stress response of the scaffold/hydrogel construct is a synergic effect determined by the performance of the both components. This is interesting since it suggests that the in vivo outcome of the scaffold is not only dependent upon the material architecture but also the growing tissue inside the scaffold׳s pores. On the other hand, confined compression results show that compliance of the scaffold is mainly controlled by the micro-porosity of the scaffold and less by hydrogel density in the scaffold pores. These conclusions bring together valuable information for customizing the optimal scaffold and to predict the in vivo mechanical behavior. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Stimulating in situ denitrification in an aerobic, highly permeable municipal drinking water aquifer.

    PubMed

    Critchley, K; Rudolph, D L; Devlin, J F; Schillig, P C

    2014-12-15

    A preliminary trial of a cross-injection system (CIS) was designed to stimulate in situ denitrification in an aquifer servicing an urban community in southern Ontario. It was hypothesized that this remedial strategy could be used to reduce groundwater nitrate in the aquifer such that it could remain in use as a municipal supply until the beneficial effects of local reduced nutrient loadings lead to long-term water quality improvement at the wellfield. The CIS application involved injecting a carbon source (acetate) into the subsurface using an injection-extraction well pair positioned perpendicular to the regional flow direction, up-gradient of the water supply wells, with the objective of stimulating native denitrifying bacteria. The pilot remedial strategy was targeted in a high nitrate flux zone within an aerobic and heterogeneous section of the glacial sand and gravel aquifer. Acetate injections were performed at intervals ranging from daily to bi-daily. The carbon additions led to general declines in dissolved oxygen concentrations; decreases in nitrate concentration were localized in aquifer layers where velocities were estimated to be less than 0.5m/day. NO3-(15)N and NO3-(18)O isotope data indicated the nitrate losses were due to denitrification. Relatively little nitrate was removed from groundwater in the more permeable strata, where velocities were estimated to be on the order of 18 m/day or greater. Overall, about 11 percent of the nitrate mass passing through the treatment zone was removed. This work demonstrates that stimulating in situ denitrification in an aerobic, highly conductive aquifer is challenging but achievable. Further work is needed to increase rates of denitrification in the most permeable units of the aquifer. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Stimulating in situ denitrification in an aerobic, highly permeable municipal drinking water aquifer

    NASA Astrophysics Data System (ADS)

    Critchley, K.; Rudolph, D. L.; Devlin, J. F.; Schillig, P. C.

    2014-12-01

    A preliminary trial of a cross-injection system (CIS) was designed to stimulate in situ denitrification in an aquifer servicing an urban community in southern Ontario. It was hypothesized that this remedial strategy could be used to reduce groundwater nitrate in the aquifer such that it could remain in use as a municipal supply until the beneficial effects of local reduced nutrient loadings lead to long-term water quality improvement at the wellfield. The CIS application involved injecting a carbon source (acetate) into the subsurface using an injection-extraction well pair positioned perpendicular to the regional flow direction, up-gradient of the water supply wells, with the objective of stimulating native denitrifying bacteria. The pilot remedial strategy was targeted in a high nitrate flux zone within an aerobic and heterogeneous section of the glacial sand and gravel aquifer. Acetate injections were performed at intervals ranging from daily to bi-daily. The carbon additions led to general declines in dissolved oxygen concentrations; decreases in nitrate concentration were localized in aquifer layers where velocities were estimated to be less than 0.5 m/day. NO3-15N and NO3-18O isotope data indicated the nitrate losses were due to denitrification. Relatively little nitrate was removed from groundwater in the more permeable strata, where velocities were estimated to be on the order of 18 m/day or greater. Overall, about 11 percent of the nitrate mass passing through the treatment zone was removed. This work demonstrates that stimulating in situ denitrification in an aerobic, highly conductive aquifer is challenging but achievable. Further work is needed to increase rates of denitrification in the most permeable units of the aquifer.

  12. Water homeostasis in the fish oocyte: new insights into the role and molecular regulation of a teleost-specific aquaporin.

    PubMed

    Cerdà, J; Zapater, C; Chauvigné, F; Finn, R N

    2013-02-01

    The discovery of the role of a teleost-specific aquaporin (Aqp1ab) during the process of oocyte hydration in marine fish producing pelagic (floating) eggs, recently confirmed by molecular approaches, has revealed that this mechanism is more sophisticated than initially thought. Recent phylogenetic and genomic studies suggest that Aqp1ab likely evolved by tandem duplication from a common ancestor and further neofunctionalized in oocytes for water transport. Investigations into the regulation of Aqp1ab during oogenesis indicate that the mRNA and protein product are highly accumulated during early oocyte growth, possibly through the transcriptional activation of the aqp1ab promoter by the classical nuclear progesterone receptor and perhaps by Sry-related high mobility group [HMG]-box (Sox) transcription factors. During oocyte growth and maturation, Aqp1ab intracellular trafficking may be regulated by phosphorylation and/or dephosphorylation of specific C-terminal residues in Aqp1ab, as well as by signal-mediated sorting processes. These mechanisms possibly regulate the temporal insertion of Aqp1ab into the oocyte plasma membrane during oocyte hydration, although the intracellular signaling pathways involved are yet unknown. Interestingly, in some freshwater species that spawn partially hydrated eggs, high accumulation of transcripts encoding functional Aqp1ab channels have also been found in the ovary. These findings suggest that the Aqp1ab-mediated mechanism for oocyte hydration is likely conserved in teleosts. The tight regulation of Aqp1ab during oogenesis, at both the transcriptional and posttranslational levels, highlights the essential physiological role of this water channel and opens new research avenues for understanding the molecular basis of egg formation in fish.

  13. Cross-formational flow of water into coalbed methane reservoirs: controls on relative permeability curve shape and production profile.

    PubMed

    Salmachi, Alireza; Karacan, C Özgen

    2017-03-01

    Coalbed methane (CBM) wells tend to produce large volumes of water, especially when there is hydraulic connectivity between coalbed and nearby formations. Cross-formational flow between producing coal and adjacent formations can have significant production and environmental implications, affecting economic viability of production from these shallow reservoirs. Such flows can also affect how much gas can be removed from a coalbed prior to mining and thus can have implications for methane control in mining as well. The aim of this paper is to investigate the impact of water flow from an external source into coalbed on production performance and also on reservoir variables including cleat porosity and relative permeability curves derived from production data analysis. A reservoir model is constructed to investigate the production performance of a CBM well when cross-formational flow is present between the coalbed and the overlying formation. Results show that cleat porosity calculated by analysis of production data can be more than one order of magnitude higher than actual cleat porosity. Due to hydraulic connectivity, water saturation within coalbed does not considerably change for a period of time, and hence, the peak of gas production is delayed. Upon depletion of the overlying formation, water saturation in coalbed quickly decreases. Rapid decline of water saturation in the coalbed corresponds to a sharp increase in gas production. As an important consequence, when cross-flow is present, gas and water relative permeability curves, derived from simulated production data, have distinctive features compared to the initial relative permeability curves. In the case of cross-flow, signatures of relative permeability curves are concave downward and low gas permeability for a range of water saturation, followed by rapid increase afterward for water and gas, respectively. The results and analyses presented in this work can help to assess the impact of cross

  14. Cross-formational flow of water into coalbed methane reservoirs: controls on relative permeability curve shape and production profile

    PubMed Central

    Karacan, C. Özgen

    2017-01-01

    Coalbed methane (CBM) wells tend to produce large volumes of water, especially when there is hydraulic connectivity between coalbed and nearby formations. Cross-formational flow between producing coal and adjacent formations can have significant production and environmental implications, affecting economic viability of production from these shallow reservoirs. Such flows can also affect how much gas can be removed from a coalbed prior to mining and thus can have implications for methane control in mining as well. The aim of this paper is to investigate the impact of water flow from an external source into coalbed on production performance and also on reservoir variables including cleat porosity and relative permeability curves derived from production data analysis. A reservoir model is constructed to investigate the production performance of a CBM well when cross-formational flow is present between the coalbed and the overlying formation. Results show that cleat porosity calculated by analysis of production data can be more than one order of magnitude higher than actual cleat porosity. Due to hydraulic connectivity, water saturation within coalbed does not considerably change for a period of time, and hence, the peak of gas production is delayed. Upon depletion of the overlying formation, water saturation in coalbed quickly decreases. Rapid decline of water saturation in the coalbed corresponds to a sharp increase in gas production. As an important consequence, when cross-flow is present, gas and water relative permeability curves, derived from simulated production data, have distinctive features compared to the initial relative permeability curves. In the case of cross-flow, signatures of relative permeability curves are concave downward and low gas permeability for a range of water saturation, followed by rapid increase afterward for water and gas, respectively. The results and analyses presented in this work can help to assess the impact of cross

  15. Water permeability of polyethylene terephthalate track membranes modified in plasma of dimethylaniline

    NASA Astrophysics Data System (ADS)

    Kravets, Lyubov; Dmitriev, Serguei; Gilman, Alla; Drachev, Alexander

    2004-09-01

    The surface properties and hydrodynamic characteristics of composite membranes consisting of a porous substrate, on which a polymer layer from a direct current discharge in a mixture of air and vapours of dimethylaniline was deposited, have been investigated. As a substrate, we used poly(ethylene) terephthalate track membrane (PET TM) of the thickness of 10 μ m and the effective pore diameter of 0.215 μ m (pore density is 2\\cdot 10^8 cm-2). The performed researches show that when treating the membranes in plasma, two competing processes are observed: deposition of the polymer layer on a membrane surface, that testifies increase of the mass of sample, and etching of a polymeric matrix which causes growth of effective pore diameter. The last process is stipulated by presence of oxygen in the gas mixture. Decreasing the degree of overweight of the sample at increasing the treatment time leads us to a supposition that a dominating process in this case becomes the process of gas-discharge etching. In all cases, if treating PET TM, a drop of the water contact angle occurs, i.e. hydrophilization of the membrane surface takes place that is connected first of all with a grafting of polymer layer containing polar functional groups. The research in the hydrodynamic characteristics of the initial PET TM and the membranes modified in plasma at neutral and subacid pH value of filtrate leads to a linear dependence of their permeability upon the quantity of applied pressure. It is connected with a viscous character of the flow, that is, when the diameter of the pores of the membrane is much more than the size of the water molecules. This fact shows that the macromolecules of the deposited polymer layer in this case have a compact conformation, which does not hinder the water molecules infiltration. At a lower pH value of the filtrate, the picture cardinally changes. For modified in plasma membranes a diversion from the linear relation is observed. This means that in this case

  16. Water- and solute-accessible spaces of purified peroxisomes. Evidence that peroxisomes are permeable to NAD+.

    PubMed Central

    Van Veldhoven, P; Debeer, L J; Mannaerts, G P

    1983-01-01

    Peroxisomes were purified from liver homogenates from rats, treated with the peroxisome proliferator clofibrate, by a combination of differential centrifugation and isopycnic centrifugation in iso-osmotic self-generating Percoll gradients. Structural integrity of the peroxisomes appeared to be preserved as evidenced by a high degree of catalase latency, the absence of catalase release during purification and the exclusion of inulin (mol.wt. +/- 5000). Spaces for water and solutes were measured after incubation of the peroxisomes in iso-osmotic sucrose with radioactive water or solutes and separation of the organelles from their media by centrifugation through an organic layer. Extraperoxisomal water was corrected for by the use of radioactive dextran or inulin. The sucrose, glucose, urea, methanol and acetate-accessible spaces were identical, suggesting that these spaces represent the volume in which molecules that can cross the membrane distribute. This volume equalled 50-65% of the water space. Urate and NAD+, a cofactor of peroxisomal beta-oxidation of fatty acids, also distributed in this volume, but were also partly bound. Urate and NAD+ binding was not abolished by sonication, which released the bulk of matrix catalase activity, but NAD+ binding was seriously diminished. The peroxisomal water and sucrose spaces were estimated to be 107 microliters and 55 microliters per g of liver tissue from a clofibrate-treated rat. From quantitative morphometric data [Anthony, Schmucker, Mooney & Jones (1978) J. Lipid Res. 19, 154-165] and our marker enzyme analyses, as well as from our experimentally determined water spaces of mitochondrial and microsomal fractions, it could be calculated that the volume contamination by lysosomes, mitochondria and microsomes did not exceed 1, 8 and 6% respectively. Our data indicate that apparently intact peroxisomes are permeable to a number of small molecules, including NAD+. Whether the NAD+-binding sites in sonicated peroxisomes

  17. Permeability of water and oleic acid in composite films of phase separated polypropylene and cellulose stearate blends.

    PubMed

    Krasnou, Illia; Gårdebjer, Sofie; Tarasova, Elvira; Larsson, Anette; Westman, Gunnar; Krumme, Andres

    2016-11-05

    Cellulose esters with long carbon side chains (e.g. stearate) were produced via a homogenous reaction in ionic liquids. The degree of substitution was calculated to approximately 2. The melt rheology was studied for the pure cellulose esters but also combinations of the esters and polypropylene to study the processability of a blended composite material. It was shown that the compatibility between the two components was weak, which resulted in a phase-separated composite material. The morphology and permeability of water and oleic acid of the composite films were studied and it was shown that the water permeability decreased upon addition of the cellulose ester to the polymer. The permeability of oleic acid was however unchanged, which is most probable a result of high solubility in the cellulose ester rich domains of the composites. Also, the following hypothesis is stated: cellulose stearate influence the polypropylene crystallization process by decreasing the size of spherulites.

  18. Role of aquaporins in cell proliferation: What else beyond water permeability?

    PubMed Central

    Galán-Cobo, Ana; Ramírez-Lorca, Reposo; Echevarría, Miriam

    2016-01-01

    abstract In addition to the extensive data demonstrating the importance of mammalian AQPs for the movement of water and some small solutes across the cell membrane, there is now a growing body of evidence indicating the involvement of these proteins in numerous cellular processes seemingly unrelated, at least some of them in a direct way, to their canonical function of water permeation. Here, we have presented a broad range of evidence demonstrating that these proteins have a role in cell proliferation by various different mechanisms, namely, by allowing fast cell volume regulation during cell division; by affecting progression of cell cycle and helping maintain the balance between proliferation and apoptosis, and by crosstalk with other cell membrane proteins or transcription factors that, in turn, modulate progression of the cell cycle or regulate biosynthesis pathways of cell structural components. In the end, however, after discussing all these data that strongly support a role for AQPs in the cell proliferation process, it remains impossible to conclude that all these other functions attributed to AQPs occur completely independently of their water permeability, and there is a need for new experiments designed specifically to address this interesting issue. PMID:26752515

  19. A comparison of standard methods for measuring water vapour permeability of fabrics

    NASA Astrophysics Data System (ADS)

    McCullough, Elizabeth A.; Kwon, Myoungsook; Shim, Huensup

    2003-08-01

    It is difficult for outdoor apparel manufacturers to interpret the technical information provided by fabric suppliers concerning fabric 'breathability' properties because different methods and test conditions are used. In addition, fabrics with hydrophilic components change their properties under different humidity conditions. The purpose of this study was to measure the water vapour permeability and evaporative resistance of 26 different waterproof, windproof and breathable shell fabrics using five standard test methods. The water vapour transmission rate (WVTR) was measured using the ASTM E 96 upright and inverted cup tests with water, the JIS L 1099 desiccant inverted cup test and the new ASTM F 2298 standard using the dynamic moisture permeation cell (DMPC). The evaporative resistance was measured using the ISO 11092 sweating hot plate test. The WVTRs were consistently highest when measured with the desiccant inverted cup, followed by the inverted cup, DMPC and upright cup. The upright cup was significantly correlated with the DMPC (0.97), and the desiccant inverted cup was correlated to the sweating hot plate (-0.91).

  20. Water vapour permeability of poly(lactic acid): Crystallinity and the tortuous path model

    NASA Astrophysics Data System (ADS)

    Duan, Z.; Thomas, N. L.

    2014-02-01

    The water vapour transmission rates (WVTR) through samples of polylactic acid of different crystallinities have been measured. Three different grades of commercial poly(lactic acid) (PLA) were used with different ratios of L-lactide and D-lactide to give a range of crystallinities from 0% to 50%. Sheets of PLA were prepared by melt compounding followed by compression moulding and annealing at different temperatures and for different times to give the range of crystallinities required. Crystallinity was measured by differential scanning calorimetry and the morphology of the samples was observed under crossed polars in a transmitted light microscope. Water vapour transmission rates through the films were measured at 38 °C and at a relative humidity of 90%. It was found that the measured values of WVTR decreased linearly with increasing crystallinity of the PLA from 0% to 50%. The results are discussed in terms of the effect of crystallinity on solubility and shown to fit the "Tortuous Path Model." The model was also successfully used to explain published data on water permeability of polyethylene terephthalate.

  1. Role of aquaporins in cell proliferation: What else beyond water permeability?

    PubMed

    Galán-Cobo, Ana; Ramírez-Lorca, Reposo; Echevarría, Miriam

    2016-01-01

    In addition to the extensive data demonstrating the importance of mammalian AQPs for the movement of water and some small solutes across the cell membrane, there is now a growing body of evidence indicating the involvement of these proteins in numerous cellular processes seemingly unrelated, at least some of them in a direct way, to their canonical function of water permeation. Here, we have presented a broad range of evidence demonstrating that these proteins have a role in cell proliferation by various different mechanisms, namely, by allowing fast cell volume regulation during cell division; by affecting progression of cell cycle and helping maintain the balance between proliferation and apoptosis, and by crosstalk with other cell membrane proteins or transcription factors that, in turn, modulate progression of the cell cycle or regulate biosynthesis pathways of cell structural components. In the end, however, after discussing all these data that strongly support a role for AQPs in the cell proliferation process, it remains impossible to conclude that all these other functions attributed to AQPs occur completely independently of their water permeability, and there is a need for new experiments designed specifically to address this interesting issue.

  2. Rapid Identification of Novel Inhibitors of the Human Aquaporin-1 Water Channel

    PubMed Central

    Patil, Rajkumar V.; Xu, Shouxi; van Hoek, Alfred N.; Rusinko, Andrew; Feng, Zixia; May, Jesse; Hellberg, Mark; Sharif, Najam A.; Wax, Martin B.; Irigoyen, Macarena; Carr, Grant; Brittain, Tom; Brown, Peter; Colbert, Damon; Kumari, Sindhu; Varadaraj, Kulandaiappan; Mitra, Alok K.

    2016-01-01

    Aquaporins (AQPs) are a family of membrane proteins that function as channels facilitating water transport in response to osmotic gradients. These play critical roles in several normal physiological and pathological states and are targets for drug discovery. Selective inhibition of the AQP1 water channel may provide a new approach for the treatment of several disorders including ocular hypertension/glaucoma, congestive heart failure, brain swelling associated with a stroke, corneal and macular edema, pulmonary edema, and otic disorders such as hearing loss and vertigo. We developed a high-throughput assay to screen a library of compounds as potential AQP1 modulators by monitoring the fluorescence dequenching of entrapped calcein in a confluent layer of AQP1-overexpressing CHO cells that were exposed to a hypotonic shock. Promising candidates were tested in a Xenopus oocyte-swelling assay, which confirmed the identification of two lead classes of compounds belonging to aromatic sulfonamides and dihydrobenzofurans with IC50s in the low micromolar range. These selected compounds directly inhibited water transport in AQP1-enriched stripped erythrocyte ghosts and in proteoliposomes reconstituted with purified AQP1. Validation of these lead compounds, by the three independent assays, establishes a set of attractive AQP1 blockers for developing novel, small-molecule functional modulators of human AQP1. PMID:26685080

  3. Morphology and water permeability of red blood cells from green sea turtle (Chelonia mydas).

    PubMed

    Benga, Gheorghe; Chapman, Bogdan E; Romeo, Tony; Cox, Guy C; Kuchel, Philip W

    2015-07-01

    The morphology and diffusional water permeability (P d) of red blood cells (RBCs) from green sea turtle (GST) (Chelonia mydas) are presented for the first time. The RBCs had an ellipsoidal shape with full-axis lengths (diameters): D = 14.4 μm; d = 10.2 μm; h = 2.8 μm. The values of P d (cm s(-1)) were 5.1 × 10(-3) at 15 °C, 5.7 × 10(-3) at 20 °C, 6.3 × 10(-3) at 25 °C, 6.8 × 10(-3) at 30 °C, and 7.9 × 10(-3) at 37 °C (i.e., significantly higher than in human RBCs in which it was measured to be 4.2 × 10(-3) at 25 °C, 5.0 × 10(-3) at 30 °C, and 6.2 × 10(-3) at 37 °C). There was a lack of inhibition of P d of GST RBCs by p-chloromercuribenzoate (PCMB), a well-known inhibitor of the RBC water channel proteins (WCPs). The activation energy of water diffusion (E a,d) in GST RBCs was 15.0 ± 1.6 kJ mol(-1) which is lower than the E a,d for human RBCs (~25 kJ mol(-1)). These results indicate that in the membrane of GST RBCs, there were no WCPs that were inhibited by the mercurial reagent, while the lipid bilayer of this membrane is unusually permeable to water. This is likely to be a phylogenetically old trait, like that found in amphibians and even the later birds, all of which have nucleated erythrocytes; and it is also likely to be a result of the animal's adaptation to a herbivorous diet (algae and seagrasses).

  4. Characterizing flow behavior for gas injection: Relative permeability of CO2-brine and N2-water in heterogeneous rocks

    NASA Astrophysics Data System (ADS)

    Reynolds, C. A.; Krevor, S.

    2015-12-01

    We provide a comprehensive experimental study of steady state, drainage relative permeability curves with CO2-brine and N2-deionized water, on a single Bentheimer sandstone core with a simple two-layer heterogeneity. We demonstrate that, if measured in the viscous limit, relative permeability is invariant with changing reservoir conditions, and is consistent with the continuum-scale multiphase flow theory for water wet systems. Furthermore, we show that under capillary limited conditions, the CO2-brine system is very sensitive to heterogeneity in capillary pressure, and by performing core floods under capillary limited conditions, we produce effective relative permeability curves that are flow rate and fluid parameter dependent. We suggest that the major uncertainty in past observations of CO2-brine relative permeability curves is due to the interaction of CO2 flow with pore space heterogeneity under capillary limited conditions and is not due to the effects of changing reservoir conditions. We show that the appropriate conditions for measuring intrinsic or effective relative permeability curves can be selected simply by scaling the driving force for flow by a quantification of capillary heterogeneity. Measuring one or two effective curves on a core with capillary heterogeneity that is representative of the reservoir will be sufficient for reservoir simulation.

  5. Fault Permeability Estimated From Rate of Sea Water Recharge Into an Underpressured Hydrocarbon Reservoir

    NASA Astrophysics Data System (ADS)

    Boles, J. R.; Horner, S.

    2003-12-01

    Methane has leaked from the offshore South Ellwood fault at least since discovery of the South Ellwood field at Platform Holly. The fault bounds the north side of the field and has 600 meters of normal offset. The reservoir, which is fractured Monterey shale at one kilometer depth, was initially 5% over hydrostatic pressure, but is currently at 25% below hydrostatic pressure. Production fluid in well tubing that connects the platform and reservoir is isolated from the ocean. New data indicate that the ocean is in direct hydraulic communication with the reservoir in the vicinity of the fault. Quartz pressure sensors were installed at about one km depth in five wells during a 15 day production shut down. A well that intersects the fault at reservoir depth (about one km subsea), shows a pressure variation that matches the frequency of the ocean tide. Within +/- 1 minute, there is no lag between the predicted tide signal and the pressure variation in the well. The pressure change is less than predicted from sea heights, which we attribute to compressibility of the gas in the fault zone. The other wells (160m-1 km from the fault) do not show the tidal signal, indicating that pressure change is not a general effect of the tide on the earth's crust. During testing, fluid pressures increased at a rate of 55 Pa/hr (0.008 psi/hr) in the well adjacent to the fault. We conclude that the pressure recovery from sub-hydrostatic conditions is due to sea water flowing down the fault into the under pressured reservoir. From this data we calculate the permeability of the South Ellwood Fault to be about 20 md, a value similar to the overall field permeability in the fractured Monterey reservoir.

  6. SCANNING ELECTRON ANALYSIS OF IRON FILINGS FROM A ZERO-VALENT IRON PERMEABLE BARRIER USED FOR GROUND WATER RESTORATION

    EPA Science Inventory

    Permeable iron reactive barriers have become a popular way to remediate contaminated ground water. Although this technology has been in use for about a decade, there is still little knowledge about long-term performance issues (l). One of the biggest concerns is the corrosion of ...

  7. SCANNING ELECTRON ANALYSIS OF IRON FILINGS FROM A ZERO-VALENT IRON PERMEABLE BARRIER USED FOR GROUND WATER RESTORATION

    EPA Science Inventory

    Permeable iron reactive barriers have become a popular way to remediate contaminated ground water. Although this technology has been in use for about a decade, there is still little knowledge about long-term performance issues (l). One of the biggest concerns is the corrosion of ...

  8. pH regulated anion permeability of aquaporin-6.

    PubMed

    Yasui, Masato

    2009-01-01

    The kidney is a model organ for transport physiology (Nielsen 1996). AQPs are well-characterized in mammalian kidneys, where they facilitate transepithelial water reabsorption. Most renal AQPs are expressed either in proximal tubule cells or in collecting duct principal cells, which are known as sites for water reabsorption. AQP1 is present in both apical and basolateral membranes of proximal tubules, and in descending limbs of Henle's loop where 70% of filtrated water is isoosmotically reabsorbed (King and Agre 1996). AQP2 is expressed in principal cells of the collecting duct; in response to vasopressin, AQP2 translocates from intracellular vesicles to the apical plasma membranes, thereby increasing water permeability to concentrate urine (Nielsen et al. 1993, 1995; Knepper 1997; Schrier 2006). AQP3 and AQP4 reside in the basolateral membranes of collecting duct principal cells, where they may provide the exit pathways for urine. AQP7, AQP8, and AQP11 are also present in the proximal tubules (Nielsen et al. 1998).A rat cDNA clone encoding AQP6 was isolated by PCR-based homologous cloning from a rat kidney cDNA library (Ma et al. 1993; Yasui et al. 1999). AQP6 has high sequence homology to AQP0, AQP2, and AQP5. A human AQP6 was also cloned (Ma et al. 1996). Interestingly, the genes encoding AQP2, AQP5, and AQP6 are mapped to chromosome band 12q13 as a family gene cluster at this locus (Ma et al. 1997). Nevertheless, AQP6 is distinct from AQP0, AQP2, and AQP5 in terms of function. Among the renal aquaporins mentioned above, AQP6 has a unique distribution and a distinct function.

  9. Multiple-pressure-tapped core holder combined with X-ray computed tomography scanning for gas-water permeability measurements of methane-hydrate-bearing sediments.

    PubMed

    Konno, Yoshihiro; Jin, Yusuke; Uchiumi, Takashi; Nagao, Jiro

    2013-06-01

    We present a novel setup for measuring the effective gas-water permeability of methane-hydrate-bearing sediments. We developed a core holder with multiple pressure taps for measuring the pressure gradient of the gas and water phases. The gas-water flooding process was simultaneously detected using an X-ray computed tomography scanner. We successfully measured the effective gas-water permeability of an artificial sandy core with methane hydrate during the gas-water flooding test.

  10. One-way water permeable valve via water-based superhydrophobic coatings

    NASA Astrophysics Data System (ADS)

    Mates, Joseph E.; Megaridis, Constantine M.

    2013-11-01

    Spray-cast superhydrophobic coatings have shown promise in commercial applications for fluid management due to their intrinsic low-cost, large-area capabilities and substrate independence (Schutzius et al. 2011). A technique of applying a light (< 2 gsm) water-based superhydrophobic coating on inherently hydrophilic cellulosic substrates to generate a preferred directionality for water absorption and transmission is presented. The mechanism described allows water to pass through a thin treated porous substrate in one direction under negligible pressure, but does not allow water to return from the opposite direction unless much greater pressure is applied. This pressure disparity ``window'' effectively creates a one-way fluid valve, with envisioned applications ranging from personal hygiene products, to oil-water separation and filtration. Combining SEM imaging with theoretical robustness factors (Tuteja et al. 2008), the penetration pressures are found to be tunable for application-specific designs by choosing a substrate based on limiting factors of fiber diameter and spacing. The process can also be modified with the addition of functionalized (e.g. antibacterial, conductive) nanoparticle fillers suited for the desired application.

  11. Integrated petrophysical and reservoir characterization workflow to enhance permeability and water saturation prediction

    NASA Astrophysics Data System (ADS)

    Al-Amri, Meshal; Mahmoud, Mohamed; Elkatatny, Salaheldin; Al-Yousef, Hasan; Al-Ghamdi, Tariq

    2017-07-01

    Accurate estimation of permeability is essential in reservoir characterization and in determining fluid flow in porous media which greatly assists optimize the production of a field. Some of the permeability prediction techniques such as Porosity-Permeability transforms and recently artificial intelligence and neural networks are encouraging but still show moderate to good match to core data. This could be due to limitation to homogenous media while the knowledge about geology and heterogeneity is indirectly related or absent. The use of geological information from core description as in Lithofacies which includes digenetic information show a link to permeability when categorized into rock types exposed to similar depositional environment. The objective of this paper is to develop a robust combined workflow integrating geology and petrophysics and wireline logs in an extremely heterogeneous carbonate reservoir to accurately predict permeability. Permeability prediction is carried out using pattern recognition algorithm called multi-resolution graph-based clustering (MRGC). We will bench mark the prediction results with hard data from core and well test analysis. As a result, we showed how much better improvements are achieved in the permeability prediction when geology is integrated within the analysis. Finally, we use the predicted permeability as an input parameter in J-function and correct for uncertainties in saturation calculation produced by wireline logs using the classical Archie equation. Eventually, high level of confidence in hydrocarbon volumes estimation is reached when robust permeability and saturation height functions are estimated in presence of important geological details that are petrophysically meaningful.

  12. Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example

    PubMed Central

    Shatil-Cohen, Arava; Sibony, Hadas; Draye, Xavier; Chaumont, François; Moran, Nava; Moshelion, Menachem

    2014-01-01

    Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is a simple and very efficient method for the determination of the osmotic water permeability coefficient (Pf) in plant protoplasts, applicable in principle also to other spherical cells such as frog oocytes. The first step of the assay is the isolation of protoplasts from the plant tissue of interest by enzymatic digestion into a chamber with an appropriate isotonic solution. The second step consists of an osmotic challenge assay: protoplasts immobilized on the bottom of the chamber are submitted to a constant perfusion starting with an isotonic solution and followed by a hypotonic solution. The cell swelling is video recorded. In the third step, the images are processed offline to yield volume changes, and the time course of the volume changes is correlated with the time course of the change in osmolarity of the chamber perfusion medium, using a curve fitting procedure written in Matlab (the ‘PfFit’), to yield Pf. PMID:25350534

  13. Determination of water permeability coefficient and its activation energy for rabbit spermatozoa.

    PubMed

    Curry, M R; Redding, B J; Watson, P F

    1995-04-01

    Critical tonicity (tonicity at which 50% of cells swell beyond their maximum volume-to-surface area ratio and lyse) of rabbit spermatozoa was measured as 45.6 mOsm at 22 degrees C. To determine the temperature effect on critical tonicity, cells were equilibrated to 15, 25, and 35 degrees C and critical tonicity was measured as 52.9, 42.2, and 32.4 mOsm, respectively. The time taken for rabbit sperm to achieve lysis at these temperatures was measured by exposing cells for increasing times to distilled water. From these results values for the permeability coefficient of rabbit spermatozoa to water (Lp) and its activation energy (Ea) were calculated. At 25 degrees C, Lp was 0.63 micron/min/atm and was clearly temperature dependent; Ea was 17.8 kcal/mol. Rabbit spermatozoa appear to have a low Lp and high Ea, the opposite of the situation seen with spermatozoa from all other species examined to date which have high Lp and low Ea. Nevertheless, the values obtained permit modeling of cooling rates for cell survival during cryopreservation in keeping with cooling rates commonly employed.

  14. Enhancing hydrophilicity and water permeability of PET track-etched membranes by advanced oxidation process

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Zdorovets, Maxim V.; Taltenov, Abzal A.

    2015-12-01

    In this study we present results on the application of advanced oxidation systems for effective and non-toxic oxidation of poly(ethylene terephthalate) track-etched membranes (PET TeMs) to improve their wettability and water transport properties. Two oxidizing systems: H2O2 under UV irradiation (H2O2/UV) and Fenton system under visible light (Fenton/H2O2/Vis) were compared. The surface of functionalized PET TeMs was characterized by using colorimetric assay, contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results clearly showed that water permeability of PET TeMs treated with H2O2/UV was improved by 28 ± 5% compared with etched-only membrane, the same parameter was found to increase by 13 ± 4% in the case of Fenton/H2O2/Vis treatment. The proposed oxidation technique is very simple, environment friendly and not requiring special equipment or expensive chemicals. The surface hydrophilicity of the membranes stored for 360 days in air between paper sheets was analyzed by contact angle test, colorimetric assay to measure concentration of carboxylic groups on the surface with toluidine blue and XPS analysis. The hydrophilic properties of oxidized PET TeMs were found to be stable for a long period of time.

  15. New halogenated disinfection byproducts in swimming pool water and their permeability across skin.

    PubMed

    Xiao, Feng; Zhang, Xiangru; Zhai, Hongyan; Lo, Irene M C; Tipoe, George L; Yang, Mengting; Pan, Yang; Chen, Guanghao

    2012-07-03

    Chlorine is widely used for disinfecting public swimming pool water. The disinfectant chlorine, protecting swimmers from pathogenic infection in swimming, may be responsible for some adverse effects on swimmers' skin and health. In this study, numerous new halogenated disinfection byproducts (DBPs) in chlorinated pool water were detected with a powerful precursor ion scan method using electrospray ionization triple quadrupole mass spectrometry, with or without preseparation with ultra performance liquid chromatography. These new pool DBPs were demonstrated to be mainly halo(nitro)phenols, resulting from chlorination of human body substances (such as urine) in the presence of bromide. Among these new DBPs, 2,4-dibromophenol, 2,4-dichlorophenol, 2-bromophenol, 2,6-dibromo-4-nitrophenol, 2-bromo-6-chloro-4-nitrophenol, and 2,6-dichloro-4-nitrophenol were fully identified or confirmed. For 2,4-dibromophenol, 2,4-dichlorophenol and 2-bromophenol with pure standard compounds available, their permeability values across human skin were measured to be 0.031, 0.021, and 0.023 cm/h, respectively. The effects of chlorine on human skin were also investigated. The interaction of chlorine with epidermis was found to generate many new halogenated DBPs as well as common DBPs; the corneous layer was observed to become rough and even form larger pores after chlorine interaction. It is recommended that swimmers should avoid urinating in pools, and avoid prolonged swimming to reduce chlorine contact and prevent accelerated permeation of DBPs across skin.

  16. [Effects of rhizosphere soil permeability on water and nutrient uptake by maize].

    PubMed

    Niu, Wen-quan; Guo, Chao

    2010-11-01

    Aimed to better understand the significance of soil microenvironment in crop growth, a pot experiment was conducted to investigate the effects of rhizosphere soil permeability on the water and nutrient uptake by maize. Under three irrigation levels (600, 400, and 200 ml per pot), three treatments of soil aeration (no tube aeration as the control, tube aeration every two days, and tube aeration every four days) were installed, and the physiological indices of maize were measured. Under the same irrigation levels, soil aeration increased the plant height, leaf area, chlorophyll contents, promoted nutrient adsorption and increased root vitality markedly. At elongation stage, treatment tube aeration every four days had the highest root vitality (8.24 mg x g(-1) x h(-1)) under the irrigation level 600 ml per pot, being significantly higher (66.7%) than that (4.94 mg x g(-1) x h(-1)) of the control. Soil aeration had no significant effects on the transpiration rate of maize, indicating that rhizosphere soil aeration could raise water and nutrient use efficiency, and improve maize growth.

  17. Effects on evaporation rates from different water-permeable pavement designs.

    PubMed

    Starke, P; Göbel, P; Coldewey, W G

    2011-01-01

    The urban water balance can be attenuated to the natural by water-permeable pavements (WPPs). Furthermore, WPPs have a 16% higher evaporation rate than impermeable pavements, which can lead to a better urban climate. Evaporation rates from pavements are influenced by the pavement surface and by the deeper layers. By a compared evaporation measurement between different WPP designs, the grain size distribution of the sub-base shows no influence on the evaporation rates in a significant way. On the contrary, a sub-base made of a twin-layer decreases the evaporation by 16% compared to a homogeneous sub-base. By a change in the colour of the paving stone, 19% higher evaporation rates could be achieved. A further comparison shows that the transpiration-effect of the grass in grass pavers increases the evaporation rates more than threefold to pervious concrete pavements. These high evapotranspiration rates can not be achieved with a pervious concrete paving stone. In spite of this, the broad field of application of the pervious concrete paving stone increases the importance in regard to the urban climate.

  18. Methods of reducing the water permeability of water and oil producing subterranean formations

    SciTech Connect

    Dalrymple, E.D.

    1992-09-15

    This patent describes a method of reducing the water produced from a subterranean formation penetrated by a wellbore without appreciably reducing the oil produced therefrom, it comprises: pumping a hydrocarbon solution of a hydrocarbon carrier liquid and a treating agent into the formation by way of the wellbore, and then discontinuing the pumping and returning the formation to production.

  19. A reliable method to assess the water permeability of a dialysis system: the global ultrafiltration coefficient.

    PubMed

    Ficheux, A; Gayrard, N; Duranton, F; Guzman, C; Szwarc, I; Vetromile, F; Brunet, P; Servel, M F; Argilés, A

    2017-02-01

    Recent randomized controlled trials suggest that sufficiently high convection post-dilutional haemodiafiltration (HC-HDF) improves survival in dialysis patients, consequently this technique is increasingly being adopted. However, when performing HC-HDF, rigorous control systems of the ultrafiltration setting are required. Assessing the global ultrafiltration coefficient of the dialysis system [GKD-UF; defined as ultrafiltration rate (QUF)/transmembrane pressure] or water permeability may be adapted to the present dialysis settings and be of value in clinics. GKD-UF was determined and its reproducibility, variability and influencing factors were specifically assessed in 15 stable patients routinely treated by high-flux haemodialysis or HC-HDF in a single unit. GKD-UF invariably followed a parabolic function with increasing QUF in dialysis and both pre- and post-dilution HC-HDF (R2 constantly >0.96). The vertex of the parabola, GKD-UF-max and related QUF were very reproducible per patient (coefficient of variation 3.9 ± 0.6 and 3.3 ± 0.3%, respectively) and they greatly varied across patients (31–42 mL/h−1/mmHg and 82–100 mL/min, respectively). GKD-UF-max and its associated QUF decreased during dialysis treatment (P < 0.01). The GKD-UF-max decrease was related to weight loss (R2 = 0.66; P = 0.0015). GKD-UF is a reliable and accurate method to assess the water permeability of a system in vivo. It varies according to dialysis setting and patient-related factors. It is an objective parameter evaluating the forces driving convection and identifies any diversion of the system during the treatment procedure. It is applicable to low- or high-flux dialysis as well as pre- or post-dilution HDF. Thus, it may be used to describe the characteristics of a dialysis system, is suitable for clinical use and may be of help for personalized prescription.

  20. A computational assessment of the permeability and salt rejection of carbon nanotube membranes and their application to water desalination

    PubMed Central

    Thomas, Michael; Corry, Ben

    2016-01-01

    Membranes made from nanomaterials such as nanotubes and graphene have been suggested to have a range of applications in water filtration and desalination, but determining their suitability for these purposes requires an accurate assessment of the properties of these novel materials. In this study, we use molecular dynamics simulations to determine the permeability and salt rejection capabilities for membranes incorporating carbon nanotubes (CNTs) at a range of pore sizes, pressures and concentrations. We include the influence of osmotic gradients and concentration build up and simulate at realistic pressures to improve the reliability of estimated membrane transport properties. We find that salt rejection is highly dependent on the applied hydrostatic pressure, meaning high rejection can be achieved with wider tubes than previously thought; while membrane permeability depends on salt concentration. The ideal size of the CNTs for desalination applications yielding high permeability and high salt rejection is found to be around 1.1 nm diameter. While there are limited energy gains to be achieved in using ultra-permeable CNT membranes in desalination by reverse osmosis, such membranes may allow for smaller plants to be built as is required when size or weight must be minimized. There are diminishing returns in further increasing membrane permeability, so efforts should focus on the fabrication of membranes containing narrow or functionalized CNTs that yield the desired rejection or selection properties rather than trying to optimize pore densities. PMID:26712639

  1. A computational assessment of the permeability and salt rejection of carbon nanotube membranes and their application to water desalination.

    PubMed

    Thomas, Michael; Corry, Ben

    2016-02-13

    Membranes made from nanomaterials such as nanotubes and graphene have been suggested to have a range of applications in water filtration and desalination, but determining their suitability for these purposes requires an accurate assessment of the properties of these novel materials. In this study, we use molecular dynamics simulations to determine the permeability and salt rejection capabilities for membranes incorporating carbon nanotubes (CNTs) at a range of pore sizes, pressures and concentrations. We include the influence of osmotic gradients and concentration build up and simulate at realistic pressures to improve the reliability of estimated membrane transport properties. We find that salt rejection is highly dependent on the applied hydrostatic pressure, meaning high rejection can be achieved with wider tubes than previously thought; while membrane permeability depends on salt concentration. The ideal size of the CNTs for desalination applications yielding high permeability and high salt rejection is found to be around 1.1 nm diameter. While there are limited energy gains to be achieved in using ultra-permeable CNT membranes in desalination by reverse osmosis, such membranes may allow for smaller plants to be built as is required when size or weight must be minimized. There are diminishing returns in further increasing membrane permeability, so efforts should focus on the fabrication of membranes containing narrow or functionalized CNTs that yield the desired rejection or selection properties rather than trying to optimize pore densities.

  2. Evaluation of the permeability properties of the Xiaojiang Fault Zone using hot springs and water wells

    NASA Astrophysics Data System (ADS)

    Shi, Zheming; Wang, Guangcai

    2017-06-01

    The permeability of a fault zone plays an important role in controlling fluid movement and seismic activity. However, the permeability properties of fault zone, particularly large-scale fault zones, are not well understood. In this study, we employed 193 hot springs and 18 groundwater monitoring wells located around the Xiaojiang Fault Zone to study the permeability properties of the fault zone. A geostatistical analysis of hot spring temperature and a tidal analysis of groundwater level were used to infer the permeability of the fault zone. Our study showed that the permeability properties inferred from hot spring temperatures are consistent with those determined from the groundwater level tidal responses. The high-permeability areas appeared in discrete, spatially restricted areas, whereas the low-permeability areas were clustered. Earthquakes were more likely to occur in the areas that showed hydrothermal activity, and earthquakes occurred more frequently in areas with relatively low temperature and permeability. These findings could be of significance in understanding fluid flow and seismic activity in the fault zone.

  3. Enzyme activities in the water column and in shallow permeable sediments from the northeastern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Arnosti, C.; Ziervogel, K.; Ocampo, L.; Ghobrial, S.

    2009-09-01

    The activities of extracellular enzymes that initiate the microbial remineralization of high molecular weight organic matter were investigated in the water column and sandy surface sediments at two sites in the northeastern Gulf of Mexico. Six fluorescently labeled polysaccharides were hydrolyzed rapidly in the water column as well as in permeable sediments. This result contrasts with previous studies carried out in environments dominated by fine-grained muds, in which the spectrum of enzymes active in the water column is quite limited compared to that of the underlying sediments. Extracts of Spirulina, Isochrysis, and Thalassiosira were also used to measure hydrolysis rates in water from one of the sites. Rates of hydrolysis of the three plankton extracts were comparable to those of the purified polysaccharides. The broad spectrum and rapid rates of hydrolysis observed in the water column at both sites in the northeastern Gulf of Mexico may be due to the permeable nature of the sediments. Fluid flux through the sediments is sufficiently high that the entire 1.5 m deep water column could filter though the sediments on timescales of a few days to two weeks. Movement of water through sediments may also transport dissolved enzymes from the sediment into the water column, enhancing the spectrum as well as the rate of water column enzymatic activities. Such interaction between the sediments and water column would permit water column microbial communities to access high molecular weight substrates that might otherwise remain unavailable as substrates.

  4. Permeability of Rubbery and Glassy Membranes of Ionic Liquid Filled Polymersome Nanoreactors in Water.

    PubMed

    So, Soonyong; Yao, Letitia J; Lodge, Timothy P

    2015-12-03

    Nanoemulsion-like polymer vesicles (polymersomes) having ionic liquid interiors dispersed in water are attractive for nanoreactor applications. In a previous study, we demonstrated that small molecules could pass through rubbery polybutadiene membranes on a time scale of seconds, which is practical for chemical transformations. It is of interest to determine how sensitive the rate of transport is to temperature, particularly for membranes in the vicinity of the glass transition (Tg). In this work, the molecular exchange rate of 1-butylimidazole through glassy polystyrene (PS) bilayer membranes is investigated via pulsed field gradient nuclear magnetic resonance (PFG-NMR) over the temperature range from 25 to 70 °C. The vesicles were prepared by the cosolvent method in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][TFSI]), and four different polystyrene-b-poly(ethylene oxide) (PS-PEO) diblock polymers with varying PS molecular weights were examined. The vesicles were transferred from the ionic liquid to water at room temperature to form nanoemulsion solutions of polymer vesicles in water. The exchange rate of 1-butylimidazole added to the aqueous solutions was observed under equilibrium conditions at each temperature. The exchange rate decreased as the membrane thickness increased, and the exchange rate through the glassy membranes was three to four times slower than through the rubbery polybutadiene membranes under the same experimental conditions. These results demonstrate that the permeability through nanosized membranes depends on both the dimension and chemistry of membrane-forming blocks. Furthermore, the exchange rate was investigated as a function of temperature in the vicinity of the Tg of PS-PEO membranes. The exchange rate, however, is not a strong function of the temperature in the vicinity of the membrane Tg, due to a combination of the nanoscopic dimension of the membrane, and some degree of solvent

  5. Simultaneous optical measurement of osmotic and diffusional water permeability in cells and liposomes

    SciTech Connect

    Ye, R.G.; Verkman, A.S.

    1989-01-24

    A quantitative description of transmembrane water transport requires specification of osmotic (Pf) and diffusional (Pd) water permeability coefficients. Methodology has been developed to measure Pf and Pd simultaneously on the basis of the sensitivity and rapid response of the fluorophore aminonaphthalenetrisulfonic acid (ANTS) to solution H2O/D2O content. Cells loaded with ANTS in an H2O buffer were subjected to an inward osmotic gradient with a D2O buffer in a stopped-flow apparatus. The time courses of cell volume (giving Pf) and H2O/D2O content (giving Pd) were recorded with dual photomultiplier detection of scattered light intensity and ANTS fluorescence, respectively. The method was validated by using sealed red cell ghosts and artificial liposomes reconstituted with the pore-forming agent gramicidin D. At 25 degrees C, red cell ghost Pf was 0.021 cm/s with Pd 0.005 cm/s (H2O/D2O exchange time 7.9 ms). Pf and Pd were inhibited by 90% and 45% upon addition of 0.5 mM HgCl2. The activation energy for Pd increased from 5.1 kcal/mol to 10 kcal/mol with addition of HgCl2 (18-35 degrees C). In 90% phosphatidylcholine (PC)/10% cholesterol liposomes prepared by bath sonication and exclusion chromatography, Pf and Pd were 5.1 X 10(-4) and 6.3 X 10(-4) cm/s, respectively (23 degrees C). Addition of gramicidin D (0.1 micrograms/mg of PC) resulted in a further increment in Pf and Pd of 7 X 10(-4) and 3 X 10(-4) cm/s, respectively. These results validate the new methodology and demonstrate its utility for rapid determination of Pf/Pd in biological membranes and in liposomes reconstituted with water channels.

  6. Role of aquaporin water channels in pleural fluid dynamics.

    PubMed

    Song, Y; Yang, B; Matthay, M A; Ma, T; Verkman, A S

    2000-12-01

    Continuous movement of fluid into and out of the pleural compartment occurs in normal chest physiology and in pathophysiological conditions associated with pleural effusions. RT-PCR screening and immunostaining revealed expression of water channel aquaporin-1 (AQP1) in microvascular endothelia near the visceral and parietal pleura and in mesothelial cells in visceral pleura. Comparative physiological measurements were done on wild-type vs. AQP1 null mice. Osmotically driven water transport was measured in anesthetized, mechanically ventilated mice from the kinetics of pleural fluid osmolality after instillation of 0.25 ml of hypertonic or hypotonic fluid into the pleural space. Osmotic equilibration of pleural fluid was rapid in wild-type mice (50% equilibration in <2 min) and remarkably slowed by greater than fourfold in AQP1 null mice. Small amounts of AQP3 transcript were also detected in pleura by RT-PCR, but osmotic water transport was not decreased in AQP3 null mice. In spontaneously breathing mice, the clearance of isosmolar saline instilled in the pleural space ( approximately 4 ml. kg(-1). h(-1)) was not affected by AQP1 deletion. In a fluid overload model produced by intraperitoneal saline administration and renal artery ligation, the accumulation of pleural fluid (approximately 0.035 ml/h) and was not affected by AQP1 deletion. Finally, in a thiourea toxicity model of acute endothelial injury causing pleural effusions and lung interstitial edema, pleural fluid accumulation in the first 3 h ( approximately 4 ml. kg(-1). h(-1)) was not affected by AQP1 deletion. These results indicate rapid osmotic equilibration across the pleural surface that is facilitated by AQP1 water channels. However, AQP1 does not appear to play a role in clinically relevant mechanisms of pleural fluid accumulation or clearance.

  7. Optimized water vapor permeability of sodium alginate films using response surface methodology

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Xu, Jiachao; Gao, Xin; Fu, Xiaoting

    2013-11-01

    The water vapor permeability (WVP) of films is important when developing pharmaceutical applications. Films are frequently used as coatings, and as such directly influence the quality of the medicine. The optimization of processing conditions for sodium alginate films was investigated using response surface methodology. Single-factor tests and Box-Behnken experimental design were employed. WVP was selected as the response variable, and the operating parameters for the single-factor tests were sodium alginate concentration, carboxymethyl cellulose (CMC) concentration and CaCl2 solution immersion time. The coefficient of determination ( R 2) was 0.97, indicating statistical significance. A minimal WVP of 0.389 8 g·mm/(m2·h·kPa) was achieved under the optimum conditions. These were found to be a sodium alginate concentration, CMC concentration and CaCl2 solution immersion time at 8.04%, 0.13%, and 12 min, respectively. This provides a reference for potential applications in manufacturing film-coated hard capsule shells.

  8. Towards high water permeability in triazine-framework-based microporous membranes for dehydration of ethanol.

    PubMed

    Tang, Yu Pan; Wang, Huan; Chung, Tai Shung

    2015-01-01

    The microstructural evolution of a series of triazine framework-based microporous (TFM) membranes under different conditions has been explored in this work. The pristine TFM membrane is in situ fabricated in the course of polymer synthesis via a facile Brønsted-acid-catalyzed cyclotrimerizaiton reaction. The as-synthesized polymer exhibits a microporous network with high thermal stability. The free volume size of the TFM membranes gradually evolved from a unimodal distribution to a bimodal distribution under annealing, as analyzed by positron annihilation lifetime spectroscopy (PALS). The emergence of the bimodal distribution is probably ascribed to the synergetic effect of quenching and thermal cyclization reaction. In addition, the fractional free volume (FFV) of the membranes presents a concave trend with increasing annealing temperature. Vapor sorption tests reveal that the mass transport properties are closely associated with the free volume evolution, which provides an optimal condition for dehydration of biofuels. A promising separation performance with extremely high water permeability has been attained for dehydration of an 85 wt % ethanol aqueous solution at 45 °C. The study on the free volume evolution of the TFM membranes may provide useful insights about the microstructure and mass transport behavior of the microporous polymeric materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Water permeability of plasma membranes of cultured rice, grape, and CH27 cells measured dielectrically.

    PubMed

    Ishikawa, E; Miyawaki, O; Nakamura, K

    1997-11-01

    The capacitance of suspensions of cultured rice cells (Oryza sativa L. ssp. japonica), grape cells (Vitis sp.), and CH27 cells originated from murine B-cell lymphoma was measured in the frequency range of 0.2 to 10 MHz. The relationship between the increase in capacitance caused by the presence of cells at 0.4 MHz, delta C, and the cell density was linear. Measurement of capacitance was useful in measurement of transitional changes in cell volume under external osmotic stress when sucrose was added. From the course of volume changes with such stress, the water permeabilities of the plasma membrane, Lp, were measured to be 0.015, 0.020, and 0.090 pm/(s.Pa) at 25 degrees C, for rice cells, grape cells, and CH27 cells, respectively. The smaller Lp for plant cells seemed to explain why preservation of plant cells by freezing is more difficult than for animal cells. From the temperature dependence of Lp, the apparent activation energies were calculated to be 12.0 +/- 2.9 and 13.0 +/- 5.2 kcal/mol for rice cells and CH27 cells, respectively.

  10. IBMX-elicited Inhibition of Water Permeability in the Isolated Rabbit Conjunctival Epithelium

    PubMed Central

    Candia, Oscar A.; Kong, Chi-Wing; Alvarez, Lawrence J.

    2008-01-01

    Agents expected to increase intracellular cAMP levels were tested on the diffusional water permeability (Pdw) of isolated rabbit conjunctival epithelia given recent indications of the apical expression of AQP5, a water channel homologue regulated by cAMP in other cell systems. For these experiments, segments of conjunctivae were mounted between Ussing-type hemichambers under short-circuit conditions. Unidirectional water fluxes (Jdw) were measured by adding 3H2O to one hemichamber and sampling from the other, while the electrical parameters (Isc and Rt) were recorded simultaneously. Jdw were determined under control conditions and after the introduction of forskolin, dibutyryl-cAMP, rolipram and IBMX. All agents reduced Jdw, with rolipram and IBMX the most effective inhibitors (≈ 28% reduction), while simultaneously evoking stimulations of the Isc; suggesting that cAMP regulates ionic transport and Pdw independently. This observation was consistent with the elimination of the IBMX-elicited Isc stimulations by the PKA inhibitor, H89, and the ineffectiveness of the sulfonamide in preventing the Jdw reductions produced by the xanthine. Data from mannitol fluxes and Arrhenius plots indicated that the IBMX-elicited Pdw reduction occurred at the level of water-transporting channels, but the specific moiety was not identified. Instead it was observed that lipophiles commonly used in other systems to uncouple cellular communication precluded the effects of IBMX on Jdw, but the mechanism for these results was not directly linked to gap-junction blockade in the conjunctiva, as assessed by the transepithelial electrical parameters. Putatively, agents such as heptanol, by also fluidizing the bilayer, may have changed the conformation of a water channel in a manner preventing down-regulation by IBMX. Nevertheless, this study uncovered an apparently unique response to cAMP elevation exhibited by the conjunctiva, namely that Pdw declines via an H89-insensitive pathway under

  11. Transalveolar osmotic and diffusional water permeability in intact mouse lung measured by a novel surface fluorescence method.

    PubMed

    Carter, E P; Matthay, M A; Farinas, J; Verkman, A S

    1996-09-01

    A surface fluorescence method was developed to measure transalveolar transport of water, protons, and solutes in intact perfused lungs. Lungs from c57 mice were removed and perfused via the pulmonary artery (approximately 2 ml/min). The airspace was filled via the trachea with physiological saline containing a membrane-impermeant fluorescent indicator (FITC-dextran or aminonapthalene trisulfonic acid, ANTS). Because fluorescence is detected only near the lung surface due to light absorption by lung tissue, the surface fluorescence signal is directly proportional to indicator concentration. Confocal microscopy confirmed that the fluorescence signal arises from fluorophores in alveoli just beneath the pleural surface. Osmotic water permeability (Pf) was measured from the time course of intraalveolar FITC-dextran fluorescence in response to changes in perfusate osmolality. Transalveolar Pf was 0.017 +/- 0.001 cm/s at 23 degrees C, independent of the solute used to induce osmosis (sucrose, NaCl, urea), independent of osmotic gradient size and direction, weakly temperature dependent (Arrhenius activation energy 5.3 kcal/mol) and inhibited by HgCl2. Pf was not affected by cAMP activation but was decreased by 43% in lung exposed to hyperoxia for 5 d. Diffusional water permeability (Pd) and Pf were measured in the same lung from intraalveolar ANTS fluorescence, which increased by 1.8-fold upon addition of 50% D2O to the perfusate, Pd was 1.3 x 10(-5) cm/s at 23 degrees C. Transalveolar proton transport was measured from FITC-dextran fluorescence upon switching perfusate pH between 7.4 and 5.6; alveolar pH half-equilibrated in 1.9 and 1.0 min without and with HCO3-, respectively. These results indicate high transalveolar water permeability in mouse lung, implicating the involvement of molecular water channels, and establish a quantitative surface fluorescence method to measure water and solute permeabilities in intact lung.

  12. Chemical dissolution-front instability associated with water-rock reactions in groundwater hydrology: Analyses of porosity-permeability relationship effects

    NASA Astrophysics Data System (ADS)

    Zhao, Chongbin; Hobbs, B. E.; Ord, A.

    2016-09-01

    Because dissolution of rocks may create and enhance groundwater flow channels, the chemical dissolution-front instability (CDFI) can control the quality of groundwater. This paper presents the theoretical analyses of porosity-permeability relationship effects on the CDFI in water-saturated porous rocks. Since the CDFI in a water-rock reaction system can be assessed by comparing the comprehensive dimensionless dynamic characteristic (CDDC) number with the corresponding critical CDDC number of the geochemical dissolution system, it is necessary to investigate theoretically how different porosity-permeability relationships can affect the CDDC number and critical CDDC number of a water-rock reaction system. With the commonly-used Kozeny-Carman (KC) formula taken as a reference porosity-permeability formula, the permeability variation indicator (PVI), which is defined as the ratio of the permeability obtained from any porosity-permeability formula to that obtained from the KC formula, is proposed to reflect the effect of the porosity-permeability formula on the CDFI in a water-rock reaction system. The theoretical results demonstrated that: (1) since the porosity-permeability formula with a higher PVI can result in a stronger Darcy flow velocity, it may have a significant influence on the CDFI in the water-rock reaction system. (2) With an increase in the PVI of a porosity-permeability formula, there is a decrease in the critical CDDC number of the water-rock reaction system. This means that the porous rock with a higher PVI can enable the CDFI to take place much easier in the water-rock reaction system. (3) The use of the porosity-permeability formula with a higher PVI can also cause an increase in both the dimensionless growth rate of a perturbation and the propagation speed of the chemical dissolution front in the water-rock reaction system.

  13. Measurements of Gas-Water Relative Permeability for Methane-Hydrate-Bearing Sediments using X-ray Computed-Tomography

    NASA Astrophysics Data System (ADS)

    Konno, Y.; Jin, Y.; Nagao, J.

    2012-04-01

    Oceanic gas hydrate deposits at high saturations have been found within sandy sediments in areas such as the Eastern Nankai Trough and the Gulf of Mexico. The recent discovery of these deposits has stimulated research and development programs exploring the use of gas hydrates as energy resources. Depressurization is thought to be a promising method for gas recovery from gas hydrates deposits; however, considerable water production is expected when this method is applied for oceanic gas hydrate deposits. The prediction of water production is a critical problem for successful gas production from these deposits. The gas-water relative permeability of gas-hydrate-bearing sediments is a key parameter to predict gas-water-ratio (GWR) during gas production. However, the experimental measurement of gas-water relative permeability for gas-hydrate-bearing sediments is a challenging problem due to a phase change (gas hydrate formation/dissociation) during gas-water flooding test. We used X-ray computed tomography (CT) and a newly-developed core holder to measure gas-water relative permeability for gas-hydrate-bearing sediments. X-ray CT was used to image a displacement front and quantify density changes during water flooding test in methane-hydrate-bearing cores. We obtained CT images every two minutes during a water flooding test for a gas-saturated methane-hydrate-bearing core. The movement of displacement front was captured from these CT images. Quantitative analysis of density change was also done to analyze the change of gas/water saturations. We developed a multi-sensor-tap core holder to minimize capillary end effect on the pressure measurements. To be able to obtain CT images by X-ray, the core holder was made of aluminum alloy. We successfully measured pressure differences of the intermediate section of the core during water flooding test. The change of pressure differences during water flooding test showed strong correlation with the movement of displacement front

  14. Enhanced water and cryoprotectant permeability of porcine oocytes after artificial expression of human and zebrafish aquaporin-3 channels.

    PubMed

    Morató, Roser; Chauvigné, François; Novo, Sergi; Bonet, Sergi; Cerdà, Joan

    2014-05-01

    One of the major obstacles for the vitrification of mature porcine oocytes with ethylene glycol is their low permeability to this cryoprotectant, which results in osmotic stress-induced cell damage and low survival. Pig blastocysts, on the other hand, show enhanced water and cryoprotectant permeability, which has been related to the transcriptional activation of aquaporin-3 (AQP3) channels at this stage of development. In this study, we asked if expression of cRNAs encoding two aquaglyceroporins, human AQP3 (hAQP3) or the zebrafish Aqp3b-T85A mutant, in porcine oocytes can increase their permeability. Microinjection of germinal-vesicle-stage oocytes with enhanced green fluorescent protein (EGFP) or AQP3 cRNAs resulted in the expression of the corresponding proteins in ∼26% of the metaphase-II stage oocytes at 40-44 hr of in vitro culture; co-injection of EGFP cRNA appeared to be a suitable marker for oocyte selection since all EGFP-positive oocytes also expressed the corresponding aquaporin. Using this method, we found that mature oocytes co-expressing EGFP and hAQP3 or EGFP and Aqp3b-T85A showed approximately a twofold increase of the hydraulic conductivity (Lp ) with respect non-injected or EGFP alone-injected oocytes in a 0.43 M sucrose or 1.3 M ethylene glycol solution, whereas the ethylene glycol permeability (PEG ) of EGFP + hAQP3 and EGFP + Aqp3b-T85A oocytes was 6.7- and 12-fold higher, respectively, than control oocytes. These data demonstrate that the artificial expression of aquaglyceroporins in porcine metaphase-II oocytes improves their permeability, and that the zebrafish Aqp3b-T85A mutant is more efficient than the human channel at increasing the oocyte permeability to ethylene glycol. © 2014 Wiley Periodicals, Inc.

  15. Water pulse migration through semi-infinite vertical unsaturated porous column with special relative-permeability functions: Exact solutions

    NASA Astrophysics Data System (ADS)

    Hayek, Mohamed

    2014-09-01

    The paper presents certain exact solutions describing the vertical movement of a water pulse through a semi-infinite unsaturated porous column. The saturation-based form of the Richards' equation is used with special power law relative-permeability functions. Both capillary and gravity effects are taken into account. Three exact solutions are derived corresponding to three relative-permeability functions, linear, quadratic and cubic. The Richards' equation is nonlinear for the three cases. The solutions are obtained by applying a general similarity transformation. They are explicit in space and time variables and do not contain any approximation. They describe the evolution of the water saturation in the vertical column and they can be used to predict the post-infiltration movement of a finite quantity of water. Exact expressions of the masses of water leaving a given depth are also derived for the three cases. We analyze the effect of relative-permeability and capillary pressure. The proposed solutions are also useful for checking numerical schemes. One of the exact solutions is used to validate numerical solution obtained from an arbitrary initial condition. Results show that the numerical solution converges to the exact solution for large times.

  16. Performance Assessment of a Permeable Reactive Barrier for Ground Water Remediation Fifteen Years After Installation

    EPA Science Inventory

    The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminanttreatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium sourc...

  17. COST ANALYSIS OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF GROUND WATER

    EPA Science Inventory

    ABSTRACT

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating contaminated groundwater that combine subsurface fluid flow management with a passive chemical treatment zone. PRB's are a potentially more cost effective treatment...

  18. Performance Assessment of a Permeable Reactive Barrier for Ground Water Remediation Fifteen Years After Installation

    EPA Science Inventory

    The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminanttreatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium sourc...

  19. COST ANALYSIS OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF GROUND WATER

    EPA Science Inventory

    ABSTRACT

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating contaminated groundwater that combine subsurface fluid flow management with a passive chemical treatment zone. PRB's are a potentially more cost effective treatment...

  20. PERFORMANCE MONITORING OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  1. LONG-TERM PERFORMANCE ASSESSMENT OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRBs) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. The few pilot and commercial installations which have been implemented ...

  2. LONG-TERM PERFORMANCE ASSESSMENT OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRBs) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. The few pilot and commercial installations which have been implemented ...

  3. Water and solute permeabilities of Arabidopsis roots in relation to the amount and composition of aliphatic suberin

    PubMed Central

    Ranathunge, Kosala; Schreiber, Lukas

    2011-01-01

    Although it is implied that suberized apoplastic barriers of roots negatively correlate with water and solute permeabilities, direct transport measurements across roots with altered amounts and compositions of aliphatic suberin are scarce. In the present study, hydroponically grown Arabidopsis wild types (Col8 and Col0) and different suberin mutants with altered amounts and/or compositions (horst, esb1-1, and esb1-2) were used to test this hypothesis. Detailed histochemical studies revealed late development of Casparian bands and suberin lamellae in the horst mutant compared with wild types and esb mutants. Suberin analysis with gas chromatography and mass spectrometry (GC-MS) showed that the horst mutant had ∼33% lower amounts of aliphatic monomers than Col8 and Col0. In contrast, enhanced suberin mutants (esb1-1 and esb1-2) had twice the amount of suberin as the wild types. Correlative permeability measurements, which were carried out for the first time with a root pressure probe for Arabidopsis, revealed that the hydraulic conductivity (Lpr) and NaCl permeability (Psr) of the whole root system of the horst mutant were markedly greater than in the respective wild types. This was reflected by the total amounts of aliphatic suberin determined in the roots. However, increased levels of aliphatic suberin in esb mutants failed to reduce either water or NaCl permeabilities below those of the wild types. It was concluded that the simple view and the conventional assumption that the amount of root suberin negatively correlates with permeability may not always be true. The aliphatic monomer arrangement in the suberin biopolymer and its microstructure also play a role in apoplastic barrier formation. PMID:21421706

  4. Water quality impacts of hydraulic-fracturing chemicals observed in a permeable, quartz-sand aquifer

    NASA Astrophysics Data System (ADS)

    Kent, D. B.; LeBlanc, D. R.; Smith, R. L.

    2012-12-01

    A pilot scale experiment was conducted on western Cape Cod, Massachusetts to test the use of hydraulic fracturing (HF) for emplacing permeable reactive barriers (PRB) where the water table is too far below land surface to use standard excavation methods. Two PRB were emplaced 24 to 36 meters below land surface in a plume with low concentrations of perchloroethylene in oxic, mildly acidic groundwater with low concentrations of dissolved salts. The granular aquifer sediments consist of permeable sands and gravels. Quartz comprises greater than 90% by weight of the aquifer sediments but chemical reactivity of the sediments is controlled by micrometer-scale chlorite and illite and nanometer-scale aluminum-substituted goethite. HF fluids contained guar gum (gelling agent), cellulose enzyme and acetic acid (breakers), sodium borate (cross-linker), potassium (K) carbonate (pH adjustor), and sodium (Na) chloride (tracer). Water-quality impacts within about 20 meters of the PRB were monitored over a 1.7-year period following HF. Arrival of HF-chemicals was marked by an increase in boron (B) from ambient concentrations of 6 uM to >800 uM. B concentrations rose for approximately 50 days, much longer than the 22-day period over which HF was conducted. B concentrations subsequently decreased but remained 2-3 times above background concentrations for almost one year. Elevated Na and K concentrations in the HF fluids drove sorption (including ion exchange) reactions resulting in transient increases in naturally occurring major, minor, and trace cations up to 20 to 50 times background concentrations. Increases in dissolved organic carbon (DOC) and decreases in dissolved oxygen (DO) concentrations were observed as B concentrations increased. DOC concentration subsequently decreased but remained significantly above background. DO concentrations remained below detection. Dissolved iron (Fe) and manganese (Mn) concentrations increased as DO concentrations decreased below detection and

  5. Predictive permeability model of faults in crystalline rocks; verification by joint hydraulic factor (JH) obtained from water pressure tests

    NASA Astrophysics Data System (ADS)

    Barani, Hamidreza Rostami; Lashkaripour, Gholamreza; Ghafoori, Mohammad

    2014-08-01

    In the present study, a new model is proposed to predict the permeability per fracture in the fault zones by a new parameter named joint hydraulic factor (JH). JH is obtained from Water Pressure Test (WPT) and modified by the degree of fracturing. The results of JH correspond with quantitative fault zone descriptions, qualitative fracture, and fault rock properties. In this respect, a case study was done based on the data collected from Seyahoo dam site located in the east of Iran to provide the permeability prediction model of fault zone structures. Datasets including scan-lines, drill cores, and water pressure tests in the terrain of Andesite and Basalt rocks were used to analyse the variability of in-site relative permeability of a range from fault zones to host rocks. The rock mass joint permeability quality, therefore, is defined by the JH. JH data analysis showed that the background sub-zone had commonly <3 Lu (less of 5 ×10-5 m 3/s) per fracture, whereas the fault core had permeability characteristics nearly as low as the outer damage zone, represented by 8 Lu (1.3 ×10-4 m 3/s) per fracture, with occasional peaks towards 12 Lu (2 ×10-4 m 3/s) per fracture. The maximum JH value belongs to the inner damage zone, marginal to the fault core, with 14-22 Lu (2.3 ×10-4-3.6 ×10-4 m 3/s) per fracture, locally exceeding 25 Lu (4.1 ×10-4 m 3/s) per fracture. This gives a proportional relationship for JH approximately 1:4:2 between the fault core, inner damage zone, and outer damage zone of extensional fault zones in crystalline rocks. The results of the verification exercise revealed that the new approach would be efficient and that the JH parameter is a reliable scale for the fracture permeability change. It can be concluded that using short duration hydraulic tests (WPTs) and fracture frequency (FF) to calculate the JH parameter provides a possibility to describe a complex situation and compare, discuss, and weigh the hydraulic quality to make predictions as to

  6. Dynamic Changes in the Osmotic Water Permeability of Protoplast Plasma Membrane1[w

    PubMed Central

    Moshelion, Menachem; Moran, Nava; Chaumont, François

    2004-01-01

    The osmotic water permeability coefficient (Pf) of plasma membrane of maize (Zea mays) Black Mexican Sweet protoplasts changed dynamically during a hypoosmotic challenge, as revealed using a model-based computational approach. The best-fitting model had three free parameters: initial Pf, Pf rate-of-change (slopePf), and a delay, which were hypothesized to reflect changes in the number and/or activity of aquaporins in the plasma membrane. Remarkably, the swelling response was delayed 2 to 11 s after start of the noninstantaneous (but accounted for) bath flush. The Pf during the delay was ≤1 μm s−1. During the swelling period following the delay, Pf changed dynamically: within the first 15 s Pf either (1) increased gradually to approximately 8 μm s−1 (in the majority population of low-initial-Pf cells) or (2) increased abruptly to 10 to 20 μm s−1 and then decreased gradually to 3 to 6 μm s−1 (in the minority population of high-initial-Pf cells). We affirmed the validity of our computational approach by the ability to reproduce previously reported initial Pf values (including the absence of delay) in control experiments on Xenopus oocytes expressing the maize aquaporin ZmPIP2;5. Although mercury did not affect the Pf in swelling Black Mexican Sweet cells, phloretin, another aquaporin inhibitor, inhibited swelling in a predicted manner, prolonging the delay and slowing Pf increase, thereby confirming the hypothesis that Pf dynamics, delay included, reflected the varying activity of aquaporins. PMID:15310831

  7. Water Permeability Adjusts Resorption in Lung Epithelia to Increased Apical Surface Liquid Volumes.

    PubMed

    Schmidt, Hanna; Michel, Christiane; Braubach, Peter; Fauler, Michael; Neubauer, Daniel; Thompson, Kristin E; Frick, Manfred; Mizaikoff, Boris; Dietl, Paul; Wittekindt, Oliver H

    2016-11-04

    The apical surface liquid layer (ASL) covers the airways and forms a first line of defense against pathogens. Maintenance of ASL volume by airway epithelia is essential for maintaining lung function. The proteolytic activation of epithelial Na(+) channels (ENaC) is believed to be the dominating mechanism to cope with increases in ASL volumes. Alternative mechanisms, in particular increases in epithelial water permeability (Posm), have so far been regarded as rather less important. However, most studies mainly addressed immediate effects upon apical volume expansion (AVE) and increases in ASL. This study addresses the response of lung epithelia to long term AVE. NCI-H441 cells and primary human tracheal epithelial cells (hTEpC), both cultivated at air liquid interface conditions, were used as models for the lung epithelium. AVE was established by adding isotonic solution onto the apical surface of differentiated lung epithelia and time course of ASL volume restoration was assessed by the D2O dilution method. Concomitant ion transport was investigated in Ussing chambers. We identified a low resorptive state (lowRS) immediately after AVE, which coincided with proteolytic ion transport activation within 10 to 15 min after AVE. The main clearance of excess ASL occurred during a delayed (hours after AVE) high resorptive state (highRS), which did not correlate with ion transport activation. Instead, highRS onset coincided with an increase in Posm, which depended on aquapoprin upregulation. In summary, our data demonstrates that, besides to ion transport activation, modulation of Posm is a major mechanism to compensate long-term AVE in lung epithelia.

  8. Water transport by GLUT2 expressed in Xenopus laevis oocytes

    PubMed Central

    Zeuthen, Thomas; Zeuthen, Emil; MacAulay, Nanna

    2007-01-01

    The glucose transporter GLUT2 has been shown to also transport water. In the present paper we investigated the relation between sugar and water transport in human GLUT2 expressed in Xenopus oocytes. Sugar transport was determined from uptakes of non-metabolizable glucose analogues, primarily 3-O-methyl-d-glucopyranoside; key experimental results were confirmed using d(+)-glucose. Water transport was derived from changes in oocyte volume monitored at a high resolution (20 pl, 1 s). Expression of GLUT2 induced a sugar permeability, PS, of about 5 × 10−6 cm s−1 and a passive water permeability, Lp, of 5.5 × 10−5 cm s−1. Accordingly, the passive water permeability of a GLUT2 protein is about 10 times higher than its sugar permeability. Both permeabilities were abolished by phloretin. Isosmotic addition of sugar to the bathing solution (replacing mannitol) induced two parallel components of water influx in GLUT2, one by osmosis and one by cotransport. The osmotic driving force arose from sugar accumulation at the intracellular side of the membrane and was given by an intracellular diffusion coefficient for sugar of 10−6 cm2 s−1, one-fifth of the free solution value. The diffusion coefficient was determined in oocytes coexpressing GLUT2 and the water channel AQP1 where water transport was predominantly osmotic. By the cotransport mechanism about 35 water molecules were transported for each sugar molecule by a mechanism within the GLUT2. These water molecules could be transported uphill, against an osmotic gradient, energized by the flux of sugar. This capacity for cotransport is 10 times smaller than that of the Na+-coupled glucose transporters (SGLT1). The physiological role of GLUT2 for intestinal transport under conditions of high luminal sugar concentrations is discussed. PMID:17158169

  9. The water channel aquaporin-1 partitions into exosomes during reticulocyte maturation: implication for the regulation of cell volume.

    PubMed

    Blanc, Lionel; Liu, Jing; Vidal, Michel; Chasis, Joel Anne; An, Xiuli; Mohandas, Narla

    2009-10-29

    Aquaporin-1 (AQP-1), the universal water channel, is responsible for rapid response of cell volume to changes in plasma tonicity. In the membrane of the red cell the concentration of the protein is tightly controlled. Here, we show that AQP-1 is partially lost during in vitro maturation of mouse reticulocytes and that it is associated with exosomes, released throughout this process. AQP-1 in young reticulocytes localizes to the plasma membrane and also in endosomal compartments and exosomes, formed both in vitro and in vivo. During maturation a part of the total pool of AQP-1 is differentially sorted and released via the exosomal pathway. A proteasome inhibitor, MG132, suppresses secretion of AQP-1, implying that ubiquitination is a sorting signal for its release. We further show that modulation of medium tonicity in vitro regulates the secretion of AQP-1, thus showing that extracellular osmotic conditions can drive sorting of selected proteins by the exosomal pathway. These results lead us to suggest that AQP-1 sorting into exosomes may be the mechanism by which the reticulocyte adapts to environmental changes during its maturation.

  10. Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from sheep and cow.

    PubMed

    Benga, G; Borza, T; Popescu, O; Poruţiu, D; Matei, H

    1993-03-01

    1. The diffusional water permeability (p) of sheep and cow red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS). 2. There were no significant differences in the water permeability of sheep and cow RBCs, the values of p being around 3 x 10(-3) cm/sec at 20 degrees C and 5 x 10(-3) cm/sec at 37 degrees C. 3. Systematic studies of the effects of PCMBS on water diffusion indicated that in both species the maximal inhibition is reached in 60-90 min at 37 degrees C with 1 mM PCMBS. 4. The degree of inhibition increased as the temperature of measurement decreased, regardless of PCMBS concentration and incubation time. 5. The values of maximal inhibition ranged from 60-70% at 20 degrees C to 50-60% at 37 degrees C in the case of sheep RBCs, and from 45-55% at 20 degrees C to 40-50% at 37 degrees C in the case of cow RBCs. 6. The basal permeability to water of sheep RBCs was estimated as 1.0 x 10(-3) cm/sec at 20 degrees C and 2.2 x 10(-3) cm/sec at 37 degrees C, and that of cow RBCs as 1.6 x 10(-3) cm/sec at 20 degrees C and 2.7 x 10(-3) cm/sec at 37 degrees C. 7. In both species the activation energy of water diffusion was around 23 kJ/mol in control cells and reached values of around 30 kJ/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Evidence for correlation of ultrasonic attenuation and fluid permeability in very low porosity water-saturated rocks

    SciTech Connect

    Berryman, J.G.; Bonner, B.P.; Chin, R.C.Y.

    1983-07-01

    The measured amplitude A of ultrasonic pulses in intact and fractured samples of water-saturated gabbro and granite is observed to decrease as the permeability kappa increases according to the proportionality Aproportionalkappa/sup -1/2/. This relation is predicted by Biot's theory of elastic waves in fluid-saturated porous media and, therefore, suggests that Biot's attenuation mechanism may play a significant role in low porosity materials at ultrasonic frequencies. The evidence is not conclusive. The limited data set studied here is also consistent with correlations of the form Aproportionalkappa/sup -Epsilon/ where 0.2permeability of low-porosity underground repositories of radioactive waste.

  12. Comparative nuclear magnetic resonance studies on water diffusional permeability of red blood cells from mice and rats.

    PubMed

    Benga, G; Matei, H; Borza, T; Poruţiu, D; Lupşe, C

    1993-03-01

    1. The diffusional water permeability (P) of mouse and rat red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following exposure to various concentrations of p-chloromercuribenzene sulfonate (PCMBS). 2. There were no significant differences in the water permeability of mouse and rat RBCs, the values of P being around 6 x 10(-3)/sec at 20 degrees C and 11 x 10(-3) cm/sec at 37 degrees C. 3. Systematic studies of the effects of PCMBS on water diffusion indicated that the maximal inhibition is reached in 60 min at 20 degrees C with 1 mM PCMBS for the mouse RBCs and with 2 mM PCMBS for the rat RBCs. 4. The values of maximal inhibition ranged from 55-57% at 37 degrees C and reached values around 70% at 10 degrees C. 5. The degree of inhibition increased as the temperature of measurement decreased, regardless of PCMBS concentration and incubation time. 6. The basal permeability to water of mouse RBCs was estimated as 1.8 x 10(-3) cm/sec at 20 degrees C and 4.6 x 10(-3) cm/sec at 37 degrees C, and that of rat RBCs as 2.2 x 10(-3) cm/sec at 20 degrees C and 4.2 x 10(-3) cm/sec at 37 degrees C. 7. In both species the activation energy was around 27 kJ/mol and reached values over 40 kJ/mol after incubation with PCMBS in the conditions of maximal inhibition of water diffusion.

  13. Investigation of the two- and three-phase relative permeability relation in carbon dioxide-oil-water systems for light and heavy oil reservoirs

    NASA Astrophysics Data System (ADS)

    Zarivnyy, Ostap

    CO2 flooding has gained increased interest in regard to both light and heavy oil reservoirs, as a means of combining improved oil recovery and geological storage of CO2 in partially depleted oil reservoirs. Distribution and movement of CO2 in oil reservoirs is a function of the relative permeability of three phases of water, oil, and CO2 in oil reservoirs. In general, three-phase relative permeability relations are required with respect to the design of CO2 field projects for accurate predictions via numerical reservoir simulation of CO 2 flood performance and to model production and injection problems. However, a two-phase relative permeability relation is used to generate the three-phase relative permeability relation for use in reservoir simulations. An overview of the available literature indicates few attempts have been made to experimentally determine the three-phase relative permeability relation for CO2-oil-water systems under practical reservoir conditions. This research attempts to investigate the two- and three-phase relative permeability relation of CO2-oil-water systems through a series of carefully designed laboratory experiments. Fourteen experiments in two-phase systems, and four experiments in three-phase systems with heavy and light oils, were conducted in order to study the effect of pressure, temperature, viscosity, and flow rate on the relative permeability relation. It was shown that relative permeability is temperature dependent and increases with an increase in temperature. Pressure and oil viscosity had similar effects, although higher pressure caused a decrease in relative permeability to water in water-oil and water-oil-gas systems. Investigating the effect of flow rate it was found that higher injection flow rate caused increase in relative permeability values. The effect of the injection flow rate on relative permeability behaviour can be explained by the formation of emulsion during the displacement process. A set of new correlations

  14. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    This research brief presents findings over the past four years at two sites where detailed investigations by the U.S. Environmental Protection Agency (U.S. EPA) have focused on the long-term performance of PRBs under a Tri-Agency Permeable Reactive Barrier Initiative (TRI). This ...

  15. Water Quality Performance of Three Side-by-Side Permeable Pavement Surface Materials: Three Year Update

    EPA Science Inventory

    Communities are increasingly installing structural low impact development (LID) practices to mange stormwater and reduce pollutant loads associated with stormwater runoff. Permeable pavement is a LID practice that has limited research on working-scale, side-by-side performance o...

  16. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    This research brief presents findings over the past four years at two sites where detailed investigations by the U.S. Environmental Protection Agency (U.S. EPA) have focused on the long-term performance of PRBs under a Tri-Agency Permeable Reactive Barrier Initiative (TRI). This ...

  17. Water Quality Performance of Three Side-by-Side Permeable Pavement Surface Materials: Three Year Update

    EPA Science Inventory

    Communities are increasingly installing structural low impact development (LID) practices to mange stormwater and reduce pollutant loads associated with stormwater runoff. Permeable pavement is a LID practice that has limited research on working-scale, side-by-side performance o...

  18. Internal hydrological mechanism of permeable pavement and interaction with subsurface water - slides

    EPA Science Inventory

    A permeable pavement site located at the Seitz Elementary School on Fort Riley, Kansas was selected for this study. An 80-space parking lot was built behind the school as part of an EPA ORD collaboration with the U.S. Army under the Net Zero program. The parking lot design includ...

  19. Internal hydrological mechanism of permeable pavement and interaction with subsurface water

    EPA Science Inventory

    Many communities are implementing green infrastructure stormwater control measures (SCMs) in urban environments across the U.S. to mimic pre-urban, natural hydrology more closely. Permeable pavement is one SCM infrastructure that has been commonly selected for both new and retro...

  20. LONG-TERM PERFORMANCE MONITORING OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an alternative in-situ approach for remediating contaminated groundwater that combine subsurface fluid flow management with a passive chemical treatment zone. PRB's are being selected with increased frequency at waste sites (more than 40 f...

  1. Internal hydrological mechanism of permeable pavement and interaction with subsurface water - slides

    EPA Science Inventory

    A permeable pavement site located at the Seitz Elementary School on Fort Riley, Kansas was selected for this study. An 80-space parking lot was built behind the school as part of an EPA ORD collaboration with the U.S. Army under the Net Zero program. The parking lot design includ...

  2. Internal hydrological mechanism of permeable pavement and interaction with subsurface water

    EPA Science Inventory

    Many communities are implementing green infrastructure stormwater control measures (SCMs) in urban environments across the U.S. to mimic pre-urban, natural hydrology more closely. Permeable pavement is one SCM infrastructure that has been commonly selected for both new and retro...

  3. Brattleboro rats have impaired apical membrane water permeability regulation in the outer medullary collecting duct principal cells.

    PubMed

    Baturina, Galina S; Katkova, Liubov E; Zarogiannis, Sotirios G; Solenov, Evgeniy I

    2016-12-01

    Vasopressin (AVP) regulates the body salt-water balance. Brattleboro rats carry an AVP gene mutation resulting in a recessive form of central diabetes insipidus, being ideal for AVP deficiency studies. Herein, we studied the water permeability of the apical and basolateral sides of outer medullary collecting duct (OMCD) principal cells in response to dDAVP (a V2 receptor agonist) administration in Wistar and Brattleboro rats. Biophysical measurements of the water permeability (Pf ) of isolated OMCD principal cells were performed with the calcein quenching method with/without dDAVP (10(-8)  mol/L). mRNA transcripts and protein levels of AQP2, AQP3 and AQP4 were assessed by RT-PCR and western blot respectively. dDAVP increased the apical and basolateral Pf of OMCD principal cells in Wistar rats, while in Brattleboro rats this effect was present basolaterally. Long-term dDAVP administration in both strains resulted in a significant increase in mRNA expression of all assessed AQP's while only the protein levels of AQP2 and AQP3 were significantly increased. Short-term (20 minutes) dDAVP treatment of isolated OMCD fragments resulted in significantly increased plasma membrane expression of AQP2 in Wistar rats and of AQP2 and AQP3 in Brattleboro rats. In summary, dDAVP induces different expression of AQP2, AQP3 and AQP4 in Wistar and Brattleboro rats during short- and long-term treatment. In Wistar rats dDAVP mainly increased AQP2 expression while in Brattleboro rats it increased functional water permeability mainly by AQP3 expression. © 2016 John Wiley & Sons Australia, Ltd.

  4. Water Permeability across Symmetric and Asymmetric Droplet Interface Bilayers: Interaction of Cholesterol Sulfate with DPhPC.

    PubMed

    Milianta, Peter J; Muzzio, Michelle; Denver, Jacqueline; Cawley, Geoffrey; Lee, Sunghee

    2015-11-10

    Cellular membranes employ a variety of strategies for controlling the flow of small molecules into the cytoplasmic space, including incorporation of sterols for modulation of permeability and maintenance of lipid asymmetry to provide both sides of the membrane with differing biophysical properties. The specific case of cholesterol asymmetry, especially, is known to have profound effects in neurological cellular systems. Synthetic membrane models that can readily determine valuable physical parameters, such as water transport rates, for sterol-containing membranes of defined lipid composition remain in demand. We report the use of the droplet interface bilayer (DIB), composed of adherent aqueous droplets surrounded by a lipid monolayer and immersed in a hydrophobic medium, for measurement of water permeability across the membrane, with rapid visualization and ease of experimental setup. We studied droplet bilayer membranes composed of the prototypical synthetic membrane lipid (i.e., the archaeal lipid DPhPC) as well as of symmetric and asymmetric DIBs formed by DPhPC and sodium cholesterol sulfate (S-Chol). The presence of S-Chol in DPhPC in symmetric DIB reduced the passive water permeability rate (P(f)) at all concentrations and increased the activation energy (E(a)) to 17-18 kcal/mol. When only one side of the DIB contains S-Chol (asymmetric DIB), an E(a) of 14-15 kcal/mol was obtained, a value intermediate that of pure lipid and symmetrical DIB containing lipid and S-Chol. Our data are consistent with a capability for regulation of water transport by one leaflet independent of the other. The engineering of our various systems is believed to have implications for garnering detailed knowledge regarding the transport of small moieties across bilayers in a wide variety of lipid systems.

  5. Combinatorial effect of genistein and female sex-steroids on uterine fluid volume and secretion rate and aquaporin (AQP)-1, 2, 5, and 7 expression in the uterus in rats.

    PubMed

    Chinigarzadeh, Asma; Muniandy, Sekaran; Salleh, Naguib

    2017-03-01

    We hypothesized that genistein can interfere with the regulation of uterine fluid volume, secretion rate and expression of aquaporin in the uterus by female sex-steroids, i.e., estrogen and progesterone. Therefore, the aims of this study were to investigate changes in these parameters in the presence of genistein and female sex-steroids. Female Sprague-Dawley rats were ovariectomized and received 3-days estradiol-17β benzoate (E2) plus genistein (25, 50, or 100 mg kg(-1)  day(-1) ) or 3-days E2 followed by 3-days E2 plus progesterone with genistein (25, 50, or 100 mg kg(-1)  day(-1) ). A day after last treatment, uterine fluid secretion rate was determined by in vivo uterine perfusion with rats under anesthesia. Animals were sacrificed and uteri were harvested and subjected for histological analyses. Luminal/outer uterine circumference was determined and distribution of AQP-1, 2, 5, and 7 in endometrium was visualized by immunofluorescence. Expression of AQP-1, 2, 5, and 7 proteins and mRNAs were determined by Western blotting and Real-time PCR respectively. Combined treatment of E2 with high dose genistein (50 and 100 mg kg(-1)  day(-1) ) resulted in significant decrease in uterine fluid volume, secretion rate and expression of AQP-1, 2, 5, and 7 proteins and mRNAs in uterus (p < 0.05). No significant changes in these parameters were observed when 25 mg kg(-1)  day(-1) genistein was given with E2 or when genistein was given with E2 followed by E2 plus progesterone Conclusions: Decreased in uterine fluid volume, secretion rate and AQP-1, 2, 5, and 7 expression in the uterus by high dose genistein in the presence of E2 could potentially affect female fertility. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 832-844, 2017. © 2016 Wiley Periodicals, Inc.

  6. Water quality requirements for sustaining aquifer storage and recovery operations in a low permeability fractured rock aquifer.

    PubMed

    Page, Declan; Miotliński, Konrad; Dillon, Peter; Taylor, Russel; Wakelin, Steve; Levett, Kerry; Barry, Karen; Pavelic, Paul

    2011-10-01

    A changing climate and increasing urbanisation has driven interest in the use of aquifer storage and recovery (ASR) schemes as an environmental management tool to supplement conventional water resources. This study focuses on ASR with stormwater in a low permeability fractured rock aquifer and the selection of water treatment methods to prevent well clogging. In this study two different injection and recovery phases were trialed. In the first phase ~1380 m(3) of potable water was injected and recovered over four cycles. In the second phase ~3300 m(3) of treated stormwater was injected and ~2410 m(3) were subsequently recovered over three cycles. Due to the success of the potable water injection cycles, its water quality was used to set pre-treatment targets for harvested urban stormwater of ≤ 0.6 NTU turbidity, ≤ 1.7 mg/L dissolved organic carbon and ≤ 0.2 mg/L biodegradable dissolved organic carbon. A range of potential ASR pre-treatment options were subsequently evaluated resulting in the adoption of an ultrafiltration/granular activated carbon system to remove suspended solids and nutrients which cause physical and biological clogging. ASR cycle testing with potable water and treated stormwater demonstrated that urban stormwater containing variable turbidity (mean 5.5 NTU) and organic carbon (mean 8.3 mg/L) concentrations before treatment could be injected into a low transmissivity fractured rock aquifer and recovered for irrigation supplies. A small decline in permeability of the formation in the vicinity of the injection well was apparent even with high quality water that met turbidity and DOC but could not consistently achieve the BDOC criteria. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Determination of the Membrane Permeability to Water of Human Vaginal Mucosal Immune Cells at Subzero Temperatures Using Differential Scanning Calorimetry.

    PubMed

    Shu, Zhiquan; Hughes, Sean M; Fang, Cifeng; Hou, Zhiyuan; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-08-01

    To study mucosal immunity and conduct HIV vaccine trials, it is important to be able to cryopreserve mucosal specimens and recover them in functional viable form. Obtaining a good recovery depends, in part, on cooling the cells at the appropriate rate, which is determined by the rate of water transport across the cell membrane during the cooling process. In this study, the cell membrane permeabilities to water at subzero temperatures of human vaginal mucosal T cells and macrophages were measured using the differential scanning calorimetry method proposed by Devireddy et al. in 1998. Thermal histograms were measured before and after cell lysis using a Slow-Fast-Fast-Slow cooling program. The difference between the thermal histograms of the live intact cells and the dead lysed cells was used to calculate the temperature-dependent cell membrane permeability at subzero temperatures, which was assumed to follow the Arrhenius relationship, [Formula: see text], where Lpg is the permeability to water at the reference temperature (273.15 K). The results showed that Lpg = 0.0209 ± 0.0108 μm/atm/min and Ea = 41.5 ± 11.4 kcal/mol for T cells and Lpg = 0.0198 ± 0.0102 μm/atm/min and Ea = 38.2 ± 10.4 kcal/mol for macrophages, respectively, in the range 0°C to -40°C (mean ± standard deviation). Theoretical simulations predicted that the optimal cooling rate for both T cells and macrophages was about -3°C/min, which was proven by preliminary immune cell cryopreservation experiments.

  8. Copper oxide nanoparticles analysis with water as base fluid for peristaltic flow in permeable tube with heat transfer.

    PubMed

    Akbar, Noreen Sher; Raza, M; Ellahi, R

    2016-07-01

    The peristaltic flow of a copper oxide water fluid investigates the effects of heat generation and magnetic field in permeable tube is studied. The mathematical formulation is presented, the resulting equations are solved exactly. The obtained expressions for pressure gradient, pressure rise, temperature, velocity profile are described through graphs for various pertinent parameters. It is found that pressure gradient is reduce with enhancement of particle concentration and velocity profile is upturn, beside it is observed that temperature increases as more volume fraction of copper oxide. The streamlines are drawn for some physical quantities to discuss the trapping phenomenon.

  9. Performance of porcine corneal opacity and permeability assay to predict eye irritation for water-soluble cosmetic ingredients.

    PubMed

    Van den Berghe, C; Guillet, M C; Compan, D

    2005-09-01

    The purpose of this paper is to report on the ability of an in-house porcine corneal opacity and permeability assay (PCOP) to predict eye irritation for cosmetic ingredients. Preliminary studies showed that the PCOP assay could accurately predict eye irritation class for liquid and water soluble materials. To broaden our experience a larger study on 50 cosmetic ingredients of this group was conducted. A prediction model (PM) was obtained based on only one endpoint-permeability measured after 30-min exposure O.D.30. This PM allows to distinguish nonirritating compounds (if O.D.30 < 0.35) from irritating (if O.D.30 > or = 0.35). Forty-nine of the 50 ingredients tested in the PCOP assay were accurately classified. The agreement was high (concordance 98%-kappa = 0.96). For 43 of the test substances an equation PM was obtained to predict the MAS. Despite satisfactory statistical coefficients this algorithm is not recommended due to wide 95% confidence intervals. These results confirm the usefulness of the PCOP for water-soluble cosmetic ingredients to discriminate nonirritants (MAS < or = 15) and irritants (MAS >15). For this type of ingredients the PCOP seems to be better than the BCOP to predict irritation class. Future work will be done to compare the BCOP and PCOP performances and to develop an appropriate protocol for water insoluble compounds.

  10. Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

    PubMed Central

    Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

    2017-01-01

    Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time. PMID:28429740

  11. Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

    NASA Astrophysics Data System (ADS)

    Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

    2017-04-01

    Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

  12. Chemical composition of ground water and the locations of permeable zones in the Yucca Mountain area, Nevada

    USGS Publications Warehouse

    Benson, L.V.; Robison, J.H.; Blankennagel, R.K.; Ogard, A.L.

    1983-01-01

    Ten wells in the Yucca Mountain area of southern Nevada have been sampled for chemical analysis. Samples were obtained during pumping of water from the entire well bore (composite sample) and in one instance by pumping water from a single isolated interval in well UE-25b number 1. Sodium is the most abundant cation and bicarbonate the most abundant anion in all water samples. Although the general chemical compositions of individual samples are similar, there are significant differences in uncorrected carbon-14 age and in inorganic and stable-isotope composition. Flow surveys of seven wells performed using iodine-131 as a tracer indicate that groundwater production is usually from one or more discrete zones of permeability. (Author 's abstract)

  13. Effect of Spatial Variations in Temperature, Permeability, and Water Saturation on Partitioning Gas Tracer Tests to Quantify Water in the Vadose Zone and in Landfills

    NASA Astrophysics Data System (ADS)

    Li, L.; Imhoff, P. T.

    2006-12-01

    The measurement of water saturation is important in the vadose zone and in the unsaturated porous media (refuse) in bioreactor landfills. The partitioning gas tracer test (PGTT) has been successfully used to measure water saturations in soils and landfills. However, the effectiveness of the this technique for obtaining average water saturations may depend on spatial variations in temperature (landfills), which result in spatially varying Henry's law constants, as well as spatial variability in water saturations and gas permeability. Investigations of the performance of PGTTs in heterogeneous porous media are needed to assess the utility of this measurement technique in such systems. A two dimensional modeling approach was used to investigate PGTT performance in soils and landfills with spatially varying properties. Temperature, permeability and water saturations were varied spatially to examine their effect on the accuracy of water saturation measurements. The influence of tracer diffusion on PGTT results was also examined. These simulations provide guidelines for applying PGTTs in soils and landfills where spatial variability of properties is significant. Keywords: water saturation, gas tracers, spatial heterogeneity, landfills

  14. CO2 permeability of cell membranes is regulated by membrane cholesterol and protein gas channels.

    PubMed

    Itel, Fabian; Al-Samir, Samer; Öberg, Fredrik; Chami, Mohamed; Kumar, Manish; Supuran, Claudiu T; Deen, Peter M T; Meier, Wolfgang; Hedfalk, Kristina; Gros, Gerolf; Endeward, Volker

    2012-12-01

    Recent observations that some membrane proteins act as gas channels seem surprising in view of the classical concept that membranes generally are highly permeable to gases. Here, we study the gas permeability of membranes for the case of CO(2), using a previously established mass spectrometric technique. We first show that biological membranes lacking protein gas channels but containing normal amounts of cholesterol (30-50 mol% of total lipid), e.g., MDCK and tsA201 cells, in fact possess an unexpectedly low CO(2) permeability (P(CO2)) of ∼0.01 cm/s, which is 2 orders of magnitude lower than the P(CO2) of pure planar phospholipid bilayers (∼1 cm/s). Phospholipid vesicles enriched with similar amounts of cholesterol also exhibit P(CO2) ≈ 0.01 cm/s, identifying cholesterol as the major determinant of membrane P(CO2). This is confirmed by the demonstration that MDCK cells depleted of or enriched with membrane cholesterol show dramatic increases or decreases in P(CO2), respectively. We demonstrate, furthermore, that reconstitution of human AQP-1 into cholesterol-containing vesicles, as well as expression of human AQP-1 in MDCK cells, leads to drastic increases in P(CO2), indicating that gas channels are of high functional significance for gas transfer across membranes of low intrinsic gas permeability.

  15. Hydration of Volcanic Glass with Super-Critical Water and its Effect on Permeability of Volcanic Rocks

    NASA Astrophysics Data System (ADS)

    Isobe, H.

    2006-12-01

    Behavior of high-temperature, high-pressure fluid flow in volcanoes depends on permeability of rocks in fluid paths. High pressure fluids or vapors in volcanoes, which are in super-critical states, are essential factors of volcanic eruptions. Especially, phreatomagmatic eruptions are caused by excess pressures of the fluid degassed from magma body or heated water contacted with magma or high temperature rocks in volcanoes. Alteration processes of rocks and minerals with super-critical fluid can change permeability of rocks by spreading of the fluid path or obstruction with precipitated minerals. In this study, experimental reproduction on the hydration and alteration processes of rocks and minerals with super-critical fluid flow were carried out with a fluid flow apparatus. Starting materials of the experiments are powdered rhyolitic obsidian and dacite. Approximately 55g of the starting material are placed in a SUS316 sample tube. Inner diameter and length of the sample tube are 9.4mm and 572mm, respectively. Temperature gradient of the pressure vessel is controlled by triple electric furnaces. Run products are retrieved by cutting off the sample tube and observed by SEM. Permeability of run products are also measured by gas flow method. Experimental pressure is 50MPa. Flow rate of distilled water at room temperature is 0.1ml / minute pumped by a low speed high-pressure pump. Temperature of the sample is approximately 450°C for rhyolitic glass powder or 420°C for dacite powder at the first half of the sample tube, then decreased to approximately 310°C at the outlet of the sample tube. Run durations are 3 to 8 days. Obsidian grains and groundmass glass of dacite partially dissolved and changed to porous at higher than approximately 400°C. Alteration products of the volcanic glass including clay minerals, cristobalite and plagioclase occur in grain boundaries and cemented grains within a few centimeters from the outlet of the sample tube. Volcanic glass

  16. Placental ischemia-induced increases in brain water content and cerebrovascular permeability: role of TNF-α

    PubMed Central

    Warrington, Junie P.; Drummond, Heather A.; Granger, Joey P.

    2015-01-01

    Cerebrovascular complications and increased risk of encephalopathies are characteristic of preeclampsia and contribute to 40% of preeclampsia/eclampsia-related deaths. Circulating tumor necrosis factor-α (TNF-α) is elevated in preeclamptic women, and infusion of TNF-α into pregnant rats mimics characteristics of preeclampsia. While this suggests that TNF-α has a mechanistic role to promote preeclampsia, the impact of TNF-α on the cerebral vasculature during pregnancy remains unclear. We tested the hypothesis that TNF-α contributes to cerebrovascular abnormalities during placental ischemia by first infusing TNF-α in pregnant rats (200 ng/day ip, from gestational day 14 to 19) at levels to mimic those reported in preeclamptic women. TNF-α increased mean arterial pressure (MAP, P < 0.05) and brain water content in the anterior cerebrum (P < 0.05); however, TNF-α infusion had no effect on blood-brain barrier (BBB) permeability in the anterior cerebrum or posterior cerebrum. We then assessed the role of endogenous TNF-α in mediating these abnormalities in a model of placental ischemia induced by reducing uterine perfusion pressure followed by treatment with the soluble TNF-α receptor (etanercept, 0.8 mg/kg sc) on gestational day 18. Etanercept reduced placental ischemia-mediated increases in MAP, anterior brain water content (P < 0.05), and BBB permeability (202 ± 44% in placental ischemic rats to 101 ± 28% of normal pregnant rats). Our results indicate that TNF-α mechanistically contributes to cerebral edema by increasing BBB permeability and is an underlying factor in the development of cerebrovascular abnormalities associated with preeclampsia complicated by placental ischemia. PMID:26400187

  17. Agarose-dextran gels as synthetic analogs of glomerular basement membrane: water permeability.

    PubMed Central

    White, Jeffrey A; Deen, William M

    2002-01-01

    Novel agarose-dextran hydrogels were synthesized and their suitability as experimental models of glomerular basement membrane was examined by measuring their Darcy (hydraulic) permeabilities (kappa). Immobilization of large dextran molecules in agarose was achieved by electron beam irradiation. Composite gels were made with agarose volume fractions (phi(a)) of 0.04 or 0.08 and dextran volume fractions (phi(d)) ranging from 0 to 0.02 (fiber volume/gel volume), using either of two dextran molecular weights (500 or 2000). At either agarose concentration and for either size of dextran, kappa decreased markedly as the amount of dextran was increased. Statistically significant deviations from the value of kappa for pure agarose were obtained for remarkably small volume fractions of dextran: phi(d) > or = 0.0003 for phi(a) = 0.04 and phi(d) > or = 0.001 for phi(a) = 0.08. The Darcy permeabilities were much more sensitive to phi(d) than to phi(a), and were as much as 26 times smaller than those of pure agarose. Although phi(d) was an important variable, dextran molecular weight was not. The effects of dextran addition on kappa were described fairly well using simple structural idealizations. At high agarose concentrations, the dextran chains behaved as fine fibers interspersed among coarse agarose fibrils, whereas, at low concentrations, the dextran molecules began to resemble spherical obstacles embedded in agarose gels. The ability to achieve physiologically relevant Darcy permeabilities with these materials (as low as 1.6 nm2) makes them an attractive experimental model for glomerular basement membrane and possibly other extracellular matrices. PMID:11916864

  18. A Distal to Proximal Gradient of Human Choroid Plexus Development, with Antagonistic Expression of Glut1 and AQP1 in Mature Cells vs. Calbindin and PCNA in Proliferative Cells.

    PubMed

    Castañeyra-Ruiz, Leandro; González-Marrero, Ibrahim; Hernández-Abad, Luis G; Carmona-Calero, Emilia M; Meyer, Gundela; Castañeyra-Perdomo, Agustín

    2016-01-01

    The choroid plexuses (ChP) are highly vascularized tissues suspended from each of the cerebral ventricles. Their main function is to secret cerebrospinal fluid (CSF) that fills the ventricles and the subarachnoid spaces, forming a crucial system for the development and maintenance of the CNS. However, despite the essential role of the ChP-CSF system to regulate the CNS in a global manner, it still remains one of the most understudied areas in neurobiology. Here we define by immunohistochemistry the expression of different proteins involved in the maturation and functionality of the ChP from the late embryological period to maturity. We found an opposite gradient of expression between aquaporin 1 (AQP1) and glucose transporter 1 (Glut 1) that define functional maturation in the ChP periphery, and proliferating cell nuclear antigen (PCNA) and calbindin (CB), present in the ChP root zone with proliferative activity. We conclude that the maturation of the ChP matures from distal to proximal, starting in the areas nearest to the cortex, expressing in the distal, mature areas AQP1 and Glut1 (related to ChP functionality to support cortex development), and in the proximal immature areas (ChP root) CB and PCNA related to progenitor activity and proliferation.

  19. A Distal to Proximal Gradient of Human Choroid Plexus Development, with Antagonistic Expression of Glut1 and AQP1 in Mature Cells vs. Calbindin and PCNA in Proliferative Cells

    PubMed Central

    Castañeyra-Ruiz, Leandro; González-Marrero, Ibrahim; Hernández-Abad, Luis G.; Carmona-Calero, Emilia M.; Meyer, Gundela; Castañeyra-Perdomo, Agustín

    2016-01-01

    The choroid plexuses (ChP) are highly vascularized tissues suspended from each of the cerebral ventricles. Their main function is to secret cerebrospinal fluid (CSF) that fills the ventricles and the subarachnoid spaces, forming a crucial system for the development and maintenance of the CNS. However, despite the essential role of the ChP–CSF system to regulate the CNS in a global manner, it still remains one of the most understudied areas in neurobiology. Here we define by immunohistochemistry the expression of different proteins involved in the maturation and functionality of the ChP from the late embryological period to maturity. We found an opposite gradient of expression between aquaporin 1 (AQP1) and glucose transporter 1 (Glut 1) that define functional maturation in the ChP periphery, and proliferating cell nuclear antigen (PCNA) and calbindin (CB), present in the ChP root zone with proliferative activity. We conclude that the maturation of the ChP matures from distal to proximal, starting in the areas nearest to the cortex, expressing in the distal, mature areas AQP1 and Glut1 (related to ChP functionality to support cortex development), and in the proximal immature areas (ChP root) CB and PCNA related to progenitor activity and proliferation. PMID:27721744

  20. Subzero water permeability parameters and optimal freezing rates for sperm cells of the southern platyfish, Xiphophorus maculatus.

    PubMed

    Pinisetty, D; Huang, C; Dong, Q; Tiersch, T R; Devireddy, R V

    2005-06-01

    This study reports the subzero water transport characteristics (and empirically determined optimal rates for freezing) of sperm cells of live-bearing fishes of the genus Xiphophorus, specifically those of the southern platyfish Xiphophorus maculatus. These fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. Water transport during freezing of X. maculatus sperm cell suspensions was obtained using a shape-independent differential scanning calorimeter technique in the presence of extracellular ice at a cooling rate of 20 degrees C/min in three different media: (1) Hanks' balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol, and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder with a length of 52.35 microm and a diameter of 0.66 microm with an osmotically inactive cell volume (Vb) of 0.6 V0, where V0 is the isotonic or initial cell volume. This translates to a surface area, SA to initial water volume, WV ratio of 15.15 microm(-1). By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best fit membrane permeability parameters (reference membrane permeability to water at 0 degrees C, Lpg or Lpg [cpa] and the activation energy, E(Lp) or E(Lp) [cpa]) were found to range from: Lpg or Lpg [cpa] = 0.0053-0.0093 microm/minatm; E(Lp) or E(Lp) [cpa] = 9.79-29.00 kcal/mol. By incorporating these membrane permeability parameters in a recently developed generic optimal cooling rate equation (optimal cooling rate, [Formula: see text] where the units of B(opt) are degrees C/min, E(Lp) or E(Lp) [cpa] are kcal/mol, L(pg) or L(pg) [cpa] are microm/minatm and SA/WV are microm(-1)), we determined the optimal rates of freezing X. maculatus sperm cells to be 28 degrees C/min (in HBSS), 47 degrees C/min (in HBSS+14% glycerol) and 36 degrees C/min (in HBSS+10% DMSO). Preliminary empirical

  1. Estimation of water saturated permeability of soils, using 3D soil tomographic images and pore-level transport phenomena modelling

    NASA Astrophysics Data System (ADS)

    Lamorski, Krzysztof; Sławiński, Cezary; Barna, Gyöngyi

    2014-05-01

    There are some important macroscopic properties of the soil porous media such as: saturated permeability and water retention characteristics. These soil characteristics are very important as they determine soil transport processes and are commonly used as a parameters of general models of soil transport processes used extensively for scientific developments and engineering practise. These characteristics are usually measured or estimated using some statistical or phenomenological modelling, i.e. pedotransfer functions. On the physical basis, saturated soil permeability arises from physical transport processes occurring at the pore level. Current progress in modelling techniques, computational methods and X-ray micro-tomographic technology gives opportunity to use direct methods of physical modelling for pore level transport processes. Physically valid description of transport processes at micro-scale based on Navier-Stokes type modelling approach gives chance to recover macroscopic porous medium characteristics from micro-flow modelling. Water microflow transport processes occurring at the pore level are dependent on the microstructure of porous body and interactions between the fluid and the medium. In case of soils, i.e. the medium there exist relatively big pores in which water can move easily but also finer pores are present in which water transport processes are dominated by strong interactions between the medium and the fluid - full physical description of these phenomena is a challenge. Ten samples of different soils were scanned using X-ray computational microtomograph. The diameter of samples was 5 mm. The voxel resolution of CT scan was 2.5 µm. Resulting 3D soil samples images were used for reconstruction of the pore space for further modelling. 3D image threshholding was made to determine the soil grain surface. This surface was triangulated and used for computational mesh construction for the pore space. Numerical modelling of water flow through the

  2. Subzero water permeability parameters and optimal freezing rates for sperm cells of the southern platyfish, Xiphophorus maculatus✩

    PubMed Central

    Pinisetty, D.; Huang, C.; Dong, Q.; Tiersch, T.R.; Devireddy, R.V.

    2017-01-01

    This study reports the subzero water transport characteristics (and empirically determined optimal rates for freezing) of sperm cells of live-bearing fishes of the genus Xiphophorus, specifically those of the southern platyfish Xiphophorus maculatus. These fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. Water transport during freezing of X. maculatus sperm cell suspensions was obtained using a shape-independent differential scanning calorimeter technique in the presence of extracellular ice at a cooling rate of 20 °C/min in three different media: (1) Hanks’ balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol, and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder with a length of 52.35 μm and a diameter of 0.66 μm with an osmotically inactive cell volume (Vb) of 0.6V0, where V0 is the isotonic or initial cell volume. This translates to a surface area, SA to initial water volume, WV ratio of 15.15 μm−1. By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best fit membrane permeability parameters (reference membrane permeability to water at 0 °C, Lpg or Lpg [cpa] and the activation energy, ELp or ELp [cpa]) were found to range from: Lpg or Lpg [cpa] = 0.0053–0.0093 μm/min atm; ELp or ELp [cpa] = 9.79–29.00 kcal/mol. By incorporating these membrane permeability parameters in a recently developed generic optimal cooling rate equation (optimal cooling rate, Bopt=1009.5exp(−0.0546ELp)(Lpg)(SAWV) where the units of Bopt are °C/min, ELp or ELp [cpa] are kcal/mol, Lpg or Lpg [cpa] are μm/min atm and SA/WV are μm−1), we determined the optimal rates of freezing X. maculatus sperm cells to be 28 °C/min (in HBSS), 47 °C/min (in HBSS + 14% glycerol) and 36 °C/min (in HBSS + 10% DMSO). Preliminary empirical experiments suggest that the optimal rate

  3. Dry aging of beef in a bag highly permeable to water vapour.

    PubMed

    Ahnström, Maria Lundesjö; Seyfert, Mark; Hunt, Melvin C; Johnson, Dallas E

    2006-08-01

    The objective of this experiment was to compare traditional dry aging of beef with a novel technique of dry aging in a highly moisture-permeable bag. Four equal-sized sections from paired beef strip loins were dry aged traditionally, unpackaged, or packaged in the experimental bag for 14 or 21d at 3°C. No differences (P>0.05) were noted for pH, moisture, fat, total plate counts, cook loss, shear force, or any measured sensory attribute between the two aging treatments after either aging period. After 21d, however, dry aging in the bag (versus traditional dry aging) decreased (P<0.05) weight loss during aging, trim loss after aging, and yeast counts on lean tissue and increased lactic acid bacteria counts (P<0.05) on adipose and lean tissue. Dry aging in a highly moisture-permeable bag is feasible, will positively impact yields and reduce microbial spoilage, and will have no negative impact on product quality.

  4. Study of water vapour permeability of protein and gum-based edible films by a photothermal method

    NASA Astrophysics Data System (ADS)

    Tomás, S. A.; Saavedra, R.; Cruz, A.; Pedroza-Islas, R.; San Martín, E.

    2005-06-01

    The water vapour permeability of protein and gum-based edible films was studied by means of a photothermal method. The films were prepared with two basic ingredients, whey protein concentrate and mesquite gum, according to the proportions 75:25, 50:50, 25:75, and 0:100 (weight:weight). The water vapour diffusion coefficient of the analyzed films was found within the interval 0.37 × 10-6 to 2.04 × 10-6 cm^2/s, increasing linearly by increasing the mesquite gum composition in the films. The incorporation of mesquite gum in films produces less effective moisture barriers due to its highly hydrophilic property.

  5. Influence of the surface permeability on the GRACE water mass variations. Case of the Lake Chad basin.

    NASA Astrophysics Data System (ADS)

    Lopez, Teodolina; Ramillien, Guillaume; Antoine, Raphaël; Rabinowicz, Michel

    2017-04-01

    Since its launch in 2002, the Gravity Recovery And Climate Experiment (GRACE) has been measured the tiny variations of the gravity field due to redistributions of water mass in the surface envelops of Earth. At a spatial resolution of 400 km, these satellite data offer a unique perspective to understand the evolution of continental water storage at regional and global scales, and therefore they enable the monitoring of the hydrological systems such as river basins. It is well known that seasonal cycle, droughts, vegetation and human extractions are the main contributors of the hydrology signals sensed by GRACE. However, the coupling between land surface and the atmosphere is important in semi-arid and arid regions, in particular in West Africa. We propose to quantify the surface water fluxes in the Lake Chad region by using the daily (and 10-day) water mass solutions of the GRACE mission in the context of the regular West African monsoon. Alternation of the evaporation/condensation cycles during the recent period are interpreted in terms of surface vertical permeability changes that control the thermal evolution in this region [2]. GRACE solutions reveal an interannual increase of surface water mass during dry seasons, especially in 2005 and 2007. We propose that this gain of surface water mass is caused by a seasonal cycle of clay fracturing. [1] Koster et al. (2004). Science, 305, 1138-1140. [2] Lopez et al. (2016). Surv. Geophys., 37 (2), 471-502.

  6. Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics - a double-blind, randomized and controlled study.

    PubMed

    Albèr, C; Buraczewska-Norin, I; Kocherbitov, V; Saleem, S; Lodén, M; Engblom, J

    2014-10-01

    The mammalian skin is a barrier that effectively separates the water-rich interior of the body from the normally dryer exterior. Changes in the external conditions, for example ambient humidity, have been shown to affect the skin barrier properties. The prime objective of this study was to evaluate the effect of water activity of a topical formulation on skin hydration and permeability. A second objective was to gain more understanding on how two commonly used humectants, urea and glycerol, affect skin barrier function in vivo. Simple aqueous formulations were applied under occlusion to the volar forearm of healthy volunteers. Following 4-h exposure, skin water loss (by transepidermal water loss measurements), skin hydration (by Corneometry) and skin permeability (by time to vasodilation due to benzyl nicotinate exposure) were monitored. The results demonstrate that a relatively small change in the water activity of a topical formulation is sufficient to induce considerable effects on stratum corneum hydration and permeability to exogenous substances. Exposing the skin to high water activity leads to increased skin hydration and also increased permeability. Furthermore, urea and glycerol promote skin hydration and permeability even at reduced water activity of the applied formulation. These results highlight the importance of considering the water activity in topically applied formulations and the potential benefit of using humectants. The results may impact formulation optimization in how to facilitate skin hydration and to modify skin permeability by temporarily open and close the skin barrier. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  7. Monitoring water stable isotope composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Rothfuss, Youri; Vereecken, Harry; Brüggemann, Nicolas

    2013-04-01

    The water stable isotopologues 1H2H16O and 1H218O are powerful tracers of processes occurring in nature. Their slightly different masses as compared to the most abundant water isotopologue (1H216O) affect their thermodynamic (e.g. during chemical equilibrium reactions or physical phase transitions with equilibration) and kinetic (liquid and vapor phases transport processes and chemical reactions without equilibration) properties. This results in measurable differences of the isotopic composition of water within or between the different terrestrial ecosystem compartments (i.e. sub-soil, soil, surface waters, plant, and atmosphere). These differences can help addressing a number of issues, among them water balance closure and flux partitioning from the soil-plant-atmosphere continuum at the field to regional scales. In soils particularly, the isotopic composition of water (δ2H and δ18O) provides qualitative information about whether water has only infiltrated or already been re-evaporated since the last rainfall event or about the location of the evaporation front. From water stable isotope composition profiles measured in soils, it is also possible, under certain hypotheses, to derive quantitative information such as soil evaporation flux and the identification of root water uptake depths. In addition, water stable isotopologues have been well implemented into physically based Soil-Vegetation-Atmosphere Transfer models (e.g. SiSPAT-Isotope; Soil-Litter iso; TOUGHREACT) and have demonstrated their potential. However, the main disadvantage of the isotope methodology is that, contrary to other soil state variables that can be monitored over long time periods, δ2H and δ18O are typically analyzed following destructive sampling. Here, we present a non-destructive method for monitoring soil liquid water δ2H and δ18O over a wide range of water availability conditions and temperatures by sampling and measuring water vapor equilibrated with soil water using gas-permeable

  8. Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy

    PubMed Central

    Ruff, S. Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g-1 day-1 indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20–50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct

  9. Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy.

    PubMed

    Ruff, S Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct

  10. Clay, Water, and Salt: Controls on the Permeability of Fine-Grained Sedimentary Rocks.

    PubMed

    Bourg, Ian C; Ajo-Franklin, Jonathan B

    2017-09-19

    The ability to predict the permeability of fine-grained soils, sediments, and sedimentary rocks is a fundamental challenge in the geosciences with potentially transformative implications in subsurface hydrology. In particular, fine-grained sedimentary rocks (shale, mudstone) constitute about two-thirds of the sedimentary rock mass and play important roles in three energy technologies: petroleum geology, geologic carbon sequestration, and radioactive waste management. The problem is a challenging one that requires understanding the properties of complex natural porous media on several length scales. One inherent length scale, referred to hereafter as the mesoscale, is associated with the assemblages of large grains of quartz, feldspar, and carbonates over distances of tens of micrometers. Its importance is highlighted by the existence of a threshold in the core scale mechanical properties and regional scale energy uses of shale formations at a clay content Xclay ≈ 1/3, as predicted by an ideal packing model where a fine-grained clay matrix fills the gaps between the larger grains. A second important length scale, referred to hereafter as the nanoscale, is associated with the aggregation and swelling of clay particles (in particular, smectite clay minerals) over distances of tens of nanometers. Mesoscale phenomena that influence permeability are primarily mechanical and include, for example, the ability of contacts between large grains to prevent the compaction of the clay matrix. Nanoscale phenomena that influence permeability tend to be chemomechanical in nature, because they involve strong impacts of aqueous chemistry on clay swelling. The second length scale remains much less well characterized than the first, because of the inherent challenges associated with the study of strongly coupled nanoscale phenomena. Advanced models of the nanoscale properties of fine-grained media rely predominantly on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, a mean field

  11. In-vitro permeability of the human nail and of a keratin membrane from bovine hooves: influence of the partition coefficient octanol/water and the water solubility of drugs on their permeability and maximum flux.

    PubMed

    Mertin, D; Lippold, B C

    1997-01-01

    Penetration of homologous nicotinic acid esters through the human nail and a keratin membrane from bovine hooves was investigated by modified Franz diffusion cells in-vitro to study the transport mechanism. The partition coefficient octanol/water PCOct/W of the esters was over the range 7 to > 51,000. The permeability coefficient P of the nail plate as well as the hoof membrane did not increase with increasing partition coefficient or lipophilicity of the penetrating substance. This indicates that both barriers behave like hydrophilic gel membranes rather than lipophilic partition membranes as in the case of the stratum corneum. Penetration studies with the model compounds paracetamol and phenacetin showed that the maximum flux was first a function of the drug solubility in water or in the swollen keratin matrix. Dissociation hindered the diffusion of benzoic acid and pyridine through the hoof membrane. Since keratin, a protein with an isoelectric point of about 5, is also charged, this reduction can be attributed to an exclusion of the dissociating substance due to the Donnan equilibrium. Nevertheless, the simultaneous enhancement of the water solubility makes a distinct increase of the maximum flux possible. In order to screen drugs for potential topical application to the nail plate, attention has to be paid mainly to the water solubility of the compound. The bovine hoof membrane may serve as an appropriate model for the nail.

  12. Monitoring the removal of phosphate from ground water discharging through a pond-bottom permeable reactive barrier

    USGS Publications Warehouse

    McCobb, T.D.; LeBlanc, D.R.; Massey, A.J.

    2009-01-01

    Installation of a permeable reactive barrier to intercept a phosphate (PO4) plume where it discharges to a pond provided an opportunity to develop and test methods for monitoring the barrier's performance in the shallow pond-bottom sediments. The barrier is composed of zero-valent-iron mixed with the native sediments to a 0.6-m depth over a 1100-m2 area. Permanent suction, diffusion, and seepage samplers were installed to monitor PO 4 and other chemical species along vertical transects through the barrier and horizontal transects below and near the top of the barrier. Analysis of pore water sampled at about 3-cm vertical intervals by using multilevel diffusion and suction samplers indicated steep decreases in PO4 concentrations in ground water flowing upward through the barrier. Samples from vertically aligned pairs of horizontal multiport suction samplers also indicated substantial decreases in PO4 concentrations and lateral shifts in the plume's discharge area as a result of varying pond stage. Measurements from Lee-style seepage meters indicated substantially decreased PO4 concentrations in discharging ground water in the treated area; temporal trends in water flux were related to pond stage. The advantages and limitations of each sampling device are described. Preliminary analysis of the first 2 years of data indicates that the barrier reduced PO4 flux by as much as 95%. ?? 2009 National Ground Water Association.

  13. High strength, flexible and transparent nanofibrillated cellulose-nanoclay biohybrid films with tunable oxygen and water vapor permeability

    NASA Astrophysics Data System (ADS)

    Aulin, Christian; Salazar-Alvarez, German; Lindström, Tom

    2012-09-01

    A novel, technically and economically benign procedure to combine vermiculite nanoplatelets with nanocellulose fibre dispersions into functional biohybrid films is presented. Nanocellulose fibres of 20 nm diameters and several micrometers in length are mixed with high aspect ratio exfoliated vermiculite nanoplatelets through high-pressure homogenization. The resulting hybrid films obtained after solvent evaporation are stiff (tensile modulus of 17.3 GPa), strong (strength up to 257 MPa), and transparent. Scanning electron microscopy (SEM) shows that the hybrid films consist of stratified nacre-like layers with a homogenous distribution of nanoplatelets within the nanocellulose matrix. The oxygen barrier properties of the biohybrid films outperform commercial packaging materials and pure nanocellulose films showing an oxygen permeability of 0.07 cm3 μm m-2 d-1 kPa-1 at 50% relative humidity. The oxygen permeability of the hybrid films can be tuned by adjusting the composition of the films. Furthermore, the water vapor barrier properties of the biohybrid films were also significantly improved by the addition of nanoclay. The unique combination of excellent oxygen barrier behavior and optical transparency suggests the potential of these biohybrid materials as an alternative in flexible packaging of oxygen sensitive devices such as thin-film transistors or organic light-emitting diode displays, gas storage applications and as barrier coatings/laminations in large volume packaging applications.

  14. Quantitative comparison of the water permeable zone among four types of dental adhesives used with a dual-cured composite.

    PubMed

    Chang, Juhea; Platt, Jeffrey A; Yi, Keewook; Cochran, Michael A

    2006-01-01

    This study compared silver penetration in the adhesive interface among four versions of adhesives from the same manufacturer: OptiBond FL, OptiBond Solo Plus, OptiBond Solo Plus Dual Cure, and OptiBond Solo Plus Self-Etch, when coupled with dual-cured composite, CoreRestore 2 (Kerr). Twenty flat dentin surfaces were prepared using one of the adhesives and bonded with the composite, following the manufacturer's instructions. The surfaces were sectioned into 2-mm slabs and immersed in ammoniacal silver nitrate for 24 hours. Each specimen was exposed to a photodeveloping solution for eight hours and examined with a scanning electron microscope (SEM). The water permeable area occupied by the silver nitrate tracer was determined, and the relative weight of silver was analyzed by wavelength dispersive spectrometry (WDS). The OptiBond FL group had a significantly lower silver content than the other groups (p < 0.0001). Each group demonstrated different patterns of silver deposition within the adhesive layer and within various features of artifactual fracture from dehydration stress of the SEM. This may be indicative of weak links in the bonded interfaces. Simplified-step adhesives showed increased permeability, which can lead to disruption of coupling with composites.

  15. Water-soluble Moringa oleifera lectin interferes with growth, survival and cell permeability of corrosive and pathogenic bacteria.

    PubMed

    Moura, M C; Napoleão, T H; Coriolano, M C; Paiva, P M G; Figueiredo, R C B Q; Coelho, L C B B

    2015-09-01

    This work evaluated the antibacterial activity of a water-soluble Moringa oleifera seed lectin (WSMoL) by evaluating its effect on growth, survival and cell permeability of Bacillus sp., Bacillus cereus, Bacillus pumillus, Bacillus megaterium, Micrococcus sp., Pseudomonas sp., Pseudomonas fluorescens, Pseudomonas stutzeri and Serratia marcescens. In addition, the effect of lectin on membrane integrity of most sensitive species was also evaluated. All the tested bacteria are able to cause biocorrosion and some are also responsible for human infections. WSMoL inhibited the bacterial growth, induced agglutination and promoted the leakage of proteins from cells of all strains. Bactericidal effect was detected against Bacillus sp., B. pumillus, B. megaterium, Ps. fluorescens and Ser. marcescens. The bacteriostatic effect of lectin was evident with only 6 h of incubation. Fluorescence microscopy of Ser. marcescens showed that WSMoL caused loss of cell integrity and indicated an anti-biofilm activity of the lectin. WSMoL was active against the bacteria by inhibiting growth and affecting cell permeability. The lectin also interfered with membrane integrity of Ser. marcescens, the most sensitive species. The study indicates that WSMoL was active against bacteria that cause serious problems in both industrial and health sectors. Also, the study contributes for the 'state-of-art' on antibacterial mechanisms of lectins. © 2015 The Society for Applied Microbiology.

  16. Determination of the Membrane Permeability to Water of Human Vaginal Mucosal Immune Cells at Subzero Temperatures Using Differential Scanning Calorimetry

    PubMed Central

    Shu, Zhiquan; Hughes, Sean M.; Fang, Cifeng; Hou, Zhiyuan; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen

    2016-01-01

    To study mucosal immunity and conduct HIV vaccine trials, it is important to be able to cryopreserve mucosal specimens and recover them in functional viable form. Obtaining a good recovery depends, in part, on cooling the cells at the appropriate rate, which is determined by the rate of water transport across the cell membrane during the cooling process. In this study, the cell membrane permeabilities to water at subzero temperatures of human vaginal mucosal T cells and macrophages were measured using the differential scanning calorimetry method proposed by Devireddy et al. in 1998. Thermal histograms were measured before and after cell lysis using a Slow-Fast-Fast-Slow cooling program. The difference between the thermal histograms of the live intact cells and the dead lysed cells was used to calculate the temperature-dependent cell membrane permeability at subzero temperatures, which was assumed to follow the Arrhenius relationship, \\documentclass{aastex}\\usepackage{amsbsy}\\usepackage{amsfonts}\\usepackage{amssymb}\\usepackage{bm}\\usepackage{mathrsfs}\\usepackage{pifont}\\usepackage{stmaryrd}\\usepackage{textcomp}\\usepackage{portland, xspace}\\usepackage{amsmath, amsxtra}\\pagestyle{empty}\\DeclareMathSizes{10}{9}{7}{6}\\begin{document} $$L_p ( T ) = L_ { pg } * e^ { - \\frac { E_a } { R } \\left( \\frac { 1 } { T } - \\frac { 1 } { T_r } \\right) } $$ \\end{document}, where Lpg is the permeability to water at the reference temperature (273.15 K). The results showed that Lpg = 0.0209 ± 0.0108 μm/atm/min and Ea = 41.5 ± 11.4 kcal/mol for T cells and Lpg = 0.0198 ± 0.0102 μm/atm/min and Ea = 38.2 ± 10.4 kcal/mol for macrophages, respectively, in the range 0°C to −40°C (mean ± standard deviation). Theoretical simulations predicted that the optimal cooling rate for both T cells and macrophages was about −3°C/min, which was proven by preliminary immune cell cryopreservation experiments. PMID:26977578

  17. Effects of Irrigating with Treated Oil and Gas Product Water on Crop Biomass and Soil Permeability

    SciTech Connect

    Terry Brown; Jeffrey Morris; Patrick Richards; Joel Mason

    2010-09-30

    Demonstrating effective treatment technologies and beneficial uses for oil and gas produced water is essential for producers who must meet environmental standards and deal with high costs associated with produced water management. Proven, effective produced-water treatment technologies coupled with comprehensive data regarding blending ratios for productive long-term irrigation will improve the state-of-knowledge surrounding produced-water management. Effective produced-water management scenarios such as cost-effective treatment and irrigation will discourage discharge practices that result in legal battles between stakeholder entities. The goal of this work is to determine the optimal blending ratio required for irrigating crops with CBNG and conventional oil and gas produced water treated by ion exchange (IX), reverse osmosis (RO), or electro-dialysis reversal (EDR) in order to maintain the long term physical integrity of soils and to achieve normal crop production. The soils treated with CBNG produced water were characterized with significantly lower SAR values compared to those impacted with conventional oil and gas produced water. The CBNG produced water treated with RO at the 100% treatment level was significantly different from the untreated produced water, while the 25%, 50% and 75% water treatment levels were not significantly different from the untreated water. Conventional oil and gas produced water treated with EDR and RO showed comparable SAR results for the water treatment technologies. There was no significant difference between the 100% treated produced water and the control (river water). The EDR water treatment resulted with differences at each level of treatment, which were similar to RO treated conventional oil and gas water. The 100% treated water had SAR values significantly lower than the 75% and 50% treatments, which were similar (not significantly different). The results of the greenhouse irrigation study found the differences in biomass

  18. Soil Water Retention and Relative Permeability for Full Range of Saturation

    SciTech Connect

    Zhang, Z. F.

    2010-09-28

    Common conceptual models for unsaturated flow often rely on the oversimplified representation of medium pores as a bundle of cylindrical capillaries and assume that the matric potential is attributed to capillary forces only. The adsorptive surface forces are ignored. It is often assumed that aqueous flow is negligible when a soil is near or at the residual water content. These models are successful at high and medium water contents but often give poor results at low water contents. These models do not apply to conditions at which water content is less than the residual water content. We extend the lower bound of existing water-retention functions and conductivity models from residual water content to the oven-dry condition (i.e., zero water content) by defining a state-dependent, residual-water content for a soil drier than a critical value. Furthermore, a hydraulic conductivity model for smooth uniform spheres was modified by introducing a correction factor to describe the film flow-induced hydraulic conductivity for natural porous media. The total unsaturated hydraulic conductivity is the sum of those due to capillary and film flow. The extended retention and conductivity models were verified with six datasets from the literature. Results show that, when the soil is at high and intermediate water content, there is no difference between the un-extended and the extended models; when the soil is at low water content, the un-extended models overestimate the water content but under-estimate the conductivity while the extended models match the retention and conductivity measurements well.

  19. Soil Water Retention and Relative Permeability for Conditions from Oven-Dry to Full Saturation

    SciTech Connect

    Zhang, Z. F.

    2011-11-04

    Common conceptual models for unsaturated flow often rely on the oversimplified representation of medium pores as a bundle of cylindrical capillaries and assume that the matric potential is attributed to the capillary force only. The adsorptive surface forces are ignored. It is often assumed that aqueous flow is negligible when a soil is near or at the residual water content. These models are successful at high and medium water contents but often give poor results at low water contents. These models do not apply to conditions at which the water content is less than the residual water content. We extend the lower bound of existing water-retention functions and conductivity models from residual water content to the oven-dry condition (i.e., zero water content) by defining a state-dependent, residual-water content for a soil drier than a critical value. Furthermore, a hydraulic conductivity model for smooth uniform spheres was modified by introducing a correction factor to describe the film flow-induced hydraulic conductivity for natural porous media. The total unsaturated hydraulic conductivity is the sum of those due to capillary and film flow. The extended retention and conductivity models were verified measurements. Results show that, when the soil is at high and intermediate water content, there is no difference between the un-extended and the extended models; when the soil is at low water content, the un-extended models overestimate the water content but underestimate the conductivity. The extended models match the retention and conductivity measurements well.

  20. Analysis of bacterial spore permeability to water and ions using Nano-Secondary Ion Mass Spectrometry (NanoSIMS)

    SciTech Connect

    Ghosal, S; Fallon, S; Leighton, T; Wheeler, K; Hutcheon, I; Weber, P K

    2005-11-17

    Regulation of bacterial spore solvent and solute permeability is a fundamental feature of dormancy but is poorly understood. Here we present a new technique, nano-scale secondary ion mass spectrometry (NanoSIMS) that allows the direct visualization and quantification of chemical gradients within spores. Using NanoSIMS, we demonstrate the penetration of water and a simple ionic salt, LiF, into the core of Bacillus thuringiensis israelensis (Bti) spores. The results demonstrate chemical gradients spanning the outer coat to the inner spore core that are driven by concentration-dependent ionic fluxes. Using deuterated water (D{sub 2}O), we have shown that external water is either retained or exchanged with water contained within the spore. Hydration and exchange are rapid, on a timescale of < 1 minute. Our results suggest a permeation mechanism by which short-time scale diffusion into and out of the spore can occur along hydration pathways. Additional studies are in progress to define the flux rates and mechanisms controlling these processes.

  1. Crustal permeability

    USGS Publications Warehouse

    Gleeson, Tom; Ingebritsen, Steven E.

    2016-01-01

    Permeability is the primary control on fluid flow in the Earth’s crust and is key to a surprisingly wide range of geological processes, because it controls the advection of heat and solutes and the generation of anomalous pore pressures.  The practical importance of permeability – and the potential for large, dynamic changes in permeability – is highlighted by ongoing issues associated with hydraulic fracturing for hydrocarbon production (“fracking”), enhanced geothermal systems, and geologic carbon sequestration.  Although there are thousands of research papers on crustal permeability, this is the first book-length treatment.  This book bridges the historical dichotomy between the hydrogeologic perspective of permeability as a static material property and the perspective of other Earth scientists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. 

  2. Water exchange and permeability properties of the skin in three species of amphibious sea snakes (Laticauda spp.).

    PubMed

    Lillywhite, H B; Menon, J G; Menon, G K; Sheehy, C M; Tu, M C

    2009-06-01

    Evolutionary transitions between different environmental media such as air and water pose special problems with respect to skin permeability because of the dramatic changes in the driving gradients and nature of water exchange processes. Also, during the transitional periods prior to complete adaptation to a new medium, the skin is exposed to two very different sets of environmental conditions. Here, we report new data for transepidermal evaporative water loss (TEWL) and cutaneous resistance to evaporative water loss (R(s)) of sea snakes that are transitional in the sense of being amphibious and semi-terrestrial. We investigated three species of sea kraits (Elapidae: Laticaudinae) that are common to Orchid Island (Lanyu), Taiwan. Generally, R(s) of all three species is lower than that characteristic of terrestrial/xeric species of snakes measured in other taxa. Within Laticauda, R(s) is significantly greater (TEWL lower) in the more terrestrial species and lowest (TEWL highest) in the more aquatic species. Previously reported losses of water from snakes kept in seawater exhibit a reversed trend, with lower rates of loss in the more aquatic species. These data suggest selection for adaptive traits with respect to increasing exposure to the marine environment. Thus, a countergradient of traits is reflected in decreased TEWL in aerial environments and decreased net water efflux in marine environments, acting simultaneously in the three species. The pattern for TEWL correlates with ultrastructural evidence for increased lipogenesis in the stratum corneum of the more terrestrial species. The skin surfaces of all three species are hydrophobic. Species differences in this property possibly explain the pattern for water efflux when these snakes are in seawater, which remains to be investigated.

  3. The effect of salt acclimation of the water uptake and osmotic permeability of the skin of the toad (Bufo viridis, L.).

    PubMed

    Katz, U

    1987-01-01

    1. Water uptake in vivo, and water fluxes across the isolated skin were studied in salt (NaCl) acclimated toads. 2. Water uptake of acclimated toads maintained in the solution of acclimation, decreased with the environmental salinity. 3. The osmotic water permeability (Pos) of the skin increased upon salt (NaCl) acclimation, both in vivo and in vitro. 4. Pos of the skin of toads acclimated to non-permeant solutes such as sucrose (230 mmol/l) or mannitol (400 nmol/l), was greatly reduced. 5. Oxytocin (syntocinon) increased the Pos both in tap water and salt acclimated toads. In high salt (greater than 200 mmol/l NaCl) acclimated toads however, the increased Pos and water flux at larger osmotic gradients, could not be stimulated further by the hormone. 6. The adaptive nature of the selective changes in the permeability properties of the skin under salt acclimation conditions is discussed.

  4. Rectification of the water permeability in COS-7 cells at 22, 10 and 0°C.

    PubMed

    Peckys, Diana B; Kleinhans, F W; Mazur, Peter

    2011-01-01

    The osmotic and permeability parameters of a cell membrane are essential physico-chemical properties of a cell and particularly important with respect to cell volume changes and the regulation thereof. Here, we report the hydraulic conductivity, L(p), the non-osmotic volume, V(b), and the Arrhenius activation energy, E(a), of mammalian COS-7 cells. The ratio of V(b) to the isotonic cell volume, V(c iso), was 0.29. E(a), the activation energy required for the permeation of water through the cell membrane, was 10,700, and 12,000 cal/mol under hyper- and hypotonic conditions, respectively. Average values for L(p) were calculated from swell/shrink curves by using an integrated equation for L(p). The curves represented the volume changes of 358 individually measured cells, placed into solutions of nonpermeating solutes of 157 or 602 mOsm/kg (at 0, 10 or 22°C) and imaged over time. L(p) estimates for all six combinations of osmolality and temperature were calculated, resulting in values of 0.11, 0.21, and 0.10 µm/min/atm for exosmotic flow and 0.79, 1.73 and 1.87 µm/min/atm for endosmotic flow (at 0, 10 and 22°C, respectively). The unexpected finding of several fold higher L(p) values for endosmotic flow indicates highly asymmetric membrane permeability for water in COS-7. This phenomenon is known as rectification and has mainly been reported for plant cell, but only rarely for animal cells. Although the mechanism underlying the strong rectification found in COS-7 cells is yet unknown, it is a phenomenon of biological interest and has important practical consequences, for instance, in the development of optimal cryopreservation.

  5. Rectification of the Water Permeability in COS-7 Cells at 22, 10 and 0°C

    PubMed Central

    Peckys, Diana B.; Kleinhans, F. W.; Mazur, Peter

    2011-01-01

    The osmotic and permeability parameters of a cell membrane are essential physico-chemical properties of a cell and particularly important with respect to cell volume changes and the regulation thereof. Here, we report the hydraulic conductivity, Lp, the non-osmotic volume, Vb, and the Arrhenius activation energy, Ea, of mammalian COS-7 cells. The ratio of Vb to the isotonic cell volume, Vc iso, was 0.29. Ea, the activation energy required for the permeation of water through the cell membrane, was 10,700, and 12,000 cal/mol under hyper- and hypotonic conditions, respectively. Average values for Lp were calculated from swell/shrink curves by using an integrated equation for Lp. The curves represented the volume changes of 358 individually measured cells, placed into solutions of nonpermeating solutes of 157 or 602 mOsm/kg (at 0, 10 or 22°C) and imaged over time. Lp estimates for all six combinations of osmolality and temperature were calculated, resulting in values of 0.11, 0.21, and 0.10 µm/min/atm for exosmotic flow and 0.79, 1.73 and 1.87 µm/min/atm for endosmotic flow (at 0, 10 and 22°C, respectively). The unexpected finding of several fold higher Lp values for endosmotic flow indicates highly asymmetric membrane permeability for water in COS-7. This phenomenon is known as rectification and has mainly been reported for plant cell, but only rarely for animal cells. Although the mechanism underlying the strong rectification found in COS-7 cells is yet unknown, it is a phenomenon of biological interest and has important practical consequences, for instance, in the development of optimal cryopreservation. PMID:21887290

  6. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF ARSENIC IN GROUND WATER

    EPA Science Inventory

    Contamination of ground-water resources by arsenic is a widespread environmental problem; consequently, there is an escalating need for developments and improvements of remedial technologies to effectively manage arsenic contamination in ground water and soils. In June 2005, a 7 ...

  7. Field Application of a Permeable Reactive Barrier for Treatment of Arsenic in Ground Water

    EPA Science Inventory

    Contamination of ground-water resources by arsenic is a widespread environmental problem; consequently, there is an escalating need for developments and improvements of remedial technologies to effectively manage arsenic contamination in ground water and soils. In June 2005, a 9...

  8. Field Application of a Permeable Reactive Barrier for Treatment of Arsenic in Ground Water

    EPA Science Inventory

    Contamination of ground-water resources by arsenic is a widespread environmental problem; consequently, there is an escalating need for developments and improvements of remedial technologies to effectively manage arsenic contamination in ground water and soils. In June 2005, a 9...

  9. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF ARSENIC IN GROUND WATER

    EPA Science Inventory

    Contamination of ground-water resources by arsenic is a widespread environmental problem; consequently, there is an escalating need for developments and improvements of remedial technologies to effectively manage arsenic contamination in ground water and soils. In June 2005, a 7...

  10. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF ARSENIC IN GROUND WATER

    EPA Science Inventory

    Contamination of ground-water resources by arsenic is a widespread environmental problem; consequently, there is an escalating need for developments and improvements of remedial technologies to effectively manage arsenic contamination in ground water and soils. In June 2005, a 7 ...

  11. Involvement of water channels in synaptic vesicle swelling.

    PubMed

    Jeremic, Aleksandar; Cho, Won Jin; Jena, Bhanu P

    2005-10-01

    Vesicle swelling is critical for secretion; however, the underlying mechanism of synaptic vesicle (SV) swelling is unknown. A G alphai3-phospholipase A2 (PLA2)-mediated involvement of the water channel aquaporin-1 (AQP1) in the regulation of secretory vesicle swelling in the exocrine pancreas has been previously reported. In the present study, the association and involvement of water channels in SV swelling was explored. Results from the study demonstrate that water channels AQP1 and AQP6, and the heterotrimeric Go protein are associated with SVs and participate in their swelling.

  12. Cell volume kinetics of adherent epithelial cells measured by laser scanning reflection microscopy: determination of water permeability changes of renal principal cells.

    PubMed Central

    Maric, K; Wiesner, B; Lorenz, D; Klussmann, E; Betz, T; Rosenthal, W

    2001-01-01

    The water channel aquaporin-2 (AQP2), a key component of the antidiuretic machinery in the kidney, is rapidly regulated by the antidiuretic hormone vasopressin. The hormone exerts its action by inducing a translocation of AQP2 from intracellular vesicles to the cell membrane. This step requires the elevation of intracellular cyclic AMP. We describe here a new method, laser scanning reflection microscopy (LSRM), suitable for determining cellular osmotic water permeability coefficient changes in primary cultured inner medullary collecting duct (IMCD) cells. The recording of vertical-reflection-mode x-z-scan section areas of unstained, living IMCD cells proved useful and valid for the investigation of osmotic water permeability changes. The time-dependent increases of reflection-mode x-z-scan section areas of swelling cells were fitted to a single-exponential equation. The analysis of the time constants of these processes indicates a twofold increase in osmotic water permeability of IMCD cells after treatment of the cells both with forskolin, a cyclic AMP-elevating agent, and with Clostridium difficile toxin B, an inhibitor of Rho proteins that leads to depolymerization of F-actin-containing stress fibers. This indicates that both agents lead to the functional insertion of AQP2 into the cell membrane. Thus, we have established a new functional assay for the study of the regulation of the water permeability at the cellular level. PMID:11259291

  13. Permeability of edible coatings.

    PubMed

    Mishra, B; Khatkar, B S; Garg, M K; Wilson, L A

    2010-01-01

    The permeabilities of water vapour, O2 and CO2 were determined for 18 coating formulations. Water vapour transmission rate ranged from 98.8 g/m(2).day (6% beeswax) to 758.0 g/m(2).day (1.5% carboxymethyl cellulose with glycerol). O2 permeability at 14 ± 1°C and 55 ± 5% RH ranged from 1.50 to 7.95 cm(3)cm cm(-2)s(-1)Pa(-1), with CO2 permeability 2 to 6 times as high. Permeability to noncondensable gases (O2 and CO2) was higher for hydrophobic (peanut oil followed by beeswax) coatings as compared to hydrophilic (whey protein concentrate and carboxymethyl cellulose).

  14. Investigation of parameter estimation and impact of injection rate on relative permeability measurements for supercritical CO2 and water by unsteady-state method

    NASA Astrophysics Data System (ADS)

    Hiratsuka, Y.; Yamamoto, H.

    2014-12-01

    CCS (Carbon dioxide Capture and Storage) is a promising option for mitigating climate changes. To predict the behavior of injected CO2 in a deep reservoir, relative permeability of supercritical CO2 and water of the reservoir rock is one of the most fundamental and influential properties. For determining the relative permeability, we employed the unsteady state method, in which the relative permeability is determined based on history matching of transient monitoring data with a multi-phase flow model. The unsteady-state method is relatively simple and short, but obviously its accuracy strongly depends on the flow model assumed in the history matching. In this study, we conducted relative permeability measurements of supercritical CO2-water system for Berea sandstone with the unsteady-state method under a reservoir condition at a 1km depth (P= 9.5MPa, T = 44˚C). Automatic history matching was performed with an inversion simulator iTOUGH2/ECO2N for multi-phase flow system of supercritical CO2, NaCl, and water. A sensitivity analysis of relative permeability parameters for CO2 and water was carried out to better understand the uniqueness and the uncertainty of the optimum solution estimated by the history matching. Among the parameters of the Corey-type curve employed in this study, while the end-point permeability could be optimized in a limited range, the other parameters were correlated and their combinations were not unique. However it was found that any combination of these parameters results in nearly identical shapes of the curve in the range of CO2 saturation in this study (0 to 60%). The optimally estimated curve from the unsteady-method was well comparable with those from the steady-state method acquired in the previous studies. Our experiment also focuses on the impact of injection rate on the estimates of relative permeability, as it is known that the injection rate could have a significant effect on fluid distribution such as viscous fingering with

  15. Water permeation and dielectric breakdown. Water permeability in Pub Tedlar. Pub/Tedlar as a function of temperature and humidity

    NASA Technical Reports Server (NTRS)

    Orehotsky, J.

    1985-01-01

    Moisture transport and dielectric breakdown of polyvinyl butyral (PVB), Tedlar, and PVB/Tedlar composites were addressed. Data for the temperature range between 20 and 80 C showed that the moisture flux through the composite is governed by the slower material; and that the composite permeability is intermediate to those of the component material, as predicted by theory. Data for Tedlar at 71 C, showing the dependence of moisture flux on relative humidity, was also presented. Dielectric breakdown data were less precise and less conclusive. The generally applied theoretical model does not match the experimental data. The PVB/Tedlar composite exhibited greater voltage breakdown resistance than either component. Testing of EVA and EVA/Tedlar composites is underway.

  16. Intact plant MRI for the study of cell water relations, membrane permeability, cell-to-cell and long distance water transport.

    PubMed

    Van As, Henk

    2007-01-01

    Water content and hydraulic conductivity, including transport within cells, over membranes, cell-to-cell, and long-distance xylem and phloem transport, are strongly affected by plant water stress. By being able to measure these transport processes non-invasely in the intact plant situation in relation to the plant (cell) water balance, it will be possible explicitly or implicitly to examine many aspects of plant function, plant performance, and stress responses. Nuclear magnetic resonance imaging (MRI) techniques are now available that allow studying plant hydraulics on different length scales within intact plants. The information within MRI images can be manipulated in such a way that cell compartment size, water membrane permeability, water cell-to-cell transport, and xylem and phloem flow hydraulics are obtained in addition to anatomical information. These techniques are non-destructive and non-invasive and can be used to study the dynamics of plant water relations and water transport, for example, as a function of environmental (stress) conditions. An overview of NMR and MRI methods to measure such information is presented and hardware solutions for minimal invasive intact plant MRI are discussed.

  17. Vascular aspects of water uptake mechanisms in the toad skin: perfusion, diffusion, confusion.

    PubMed

    Willumsen, Niels J; Viborg, Arne L; Hillyard, Stanley D

    2007-09-01

    Blood cell flow (BCF) in the water absorbing "seat patch" region of toad skin was measured with laser Doppler flow cytometry. BCF of dehydrated toads increased by a factor of 6-8 when water contact was made and declined gradually as toads rehydrated. Water absorption was initially stimulated and declined in parallel with BCF. Water absorption measured during the initial rehydration period did not correlate with BCF and hydrated toads injected with AVT increased water absorption without an increase in BCF indicating the lack of an obligate relation between blood flow and water absorption. Aquaporins 1-3 were characterized by RT-PCR analysis of seat patch skin. AQP 1 was localized in the endothelium of subepidermal capillaries and serves as a pathway for water absorption in series with the apical and basolateral membranes of the epithelium. Dehydrated toads rehydrated more rapidly from dilute NaCl solutions than from deionized water despite the reduced osmotic gradient. BCF of toads rehydrating on 50 mM NaCl was not different than on deionized water and blocking Na+ transport with 100 microM amiloride did not reduce water absorption from 50 mM NaCl. Thus, neither circulation nor solute coupling explains the greater absorption from dilute salt solutions. Rehydration from 10 mM CaCl2 was stimulated above that of DI water by a similar degree as with 50 mM NaCl suggesting the anion might control water permeability of the skin.

  18. Paleohydrological Information from Profiles in Pore Water of Holocene Low-Permeability Cores and Groundwater Flow Simulation, Lake Kasumigaura, Japan

    NASA Astrophysics Data System (ADS)

    Takamoto, N.; Shimada, J.

    2014-12-01

    The paleohydrological information can become important to predict hydrological conditions in the future. In Japan, which hydrologically is characterized by relatively small catchment scales with steep relief of topography under humid temperate climatic conditions, the residence time of the groundwater should be relatively short. Thus the paleohydrological information preserved in the groundwater aquifer should also be limited compared with the continental aquifer. However, regarding groundwater in clay and silt sediments have low-permeability characteristic, archiving the paleohydrologic information at the time of deposition is expected.  Therefore, in this study, cores were drilled into Holocene clay and silt deposits (Site K-1 and Site K-2) in the Lake Kasumigaurain Japan, where the depositional rate 10,000 years ago was rapid and it has been affected strongly by sea level changes including transgression and regression. By using the obtained core samples and extracted pore water from the cores, paleohydrologic information was investigated, and it was tried to understand hydrologic environments at the study area during a Holocene. In addition, groundwater flow and solute transport simulation were conducted to reproduce profiles of pore water.  Results of investigation show that the profiles of pore water contents reflect sea level change and the difference in hydrological environment at that time at each site. The content of the paleo-brackish water in the culmination of transgression was about 14,000 mg/l in Cl-, -13.0‰ in δD and -2.6‰ in δ18O. It is allowed better understanding paleohydrological information by studying not only inorganic chemistry contents and stable isotopes of pore water and also the diatom fossils and groundwater flow and solute transport simulation. We will characterize the paleohydrological information of the study area acquired by those investigations and analysis.

  19. Prediction of distribution volume of vancomycin in critically ill patients using extravascular lung water and pulmonary vascular permeability indices.

    PubMed

    Imaura, Masaharu; Yokoyama, Haruko; Kohyama, Tomoki; Nagafuchi, Hiroyuki; Kohata, Yuji; Takahashi, Hiroyuki; Yamada, Yasuhiko

    2012-11-01

    Alterations in distribution volume affect the concentrations of hydrophilic drugs in plasma and tissues at the time of initial therapy. When the distribution volume of hydrophilic antimicrobials is increased in critically ill patients with a serious infection, antimicrobial concentrations are reduced, which may adversely affect the efficacy of antimicrobial therapy. A transpulmonary thermodilution technique system (PiCCO) enables measurements of pulmonary vascular permeability index (PVPI) and extravascular lung water index (EVLWI), which are related to pulmonary edema and pulmonary vascular permeability, respectively. In addition, those indices may also be related to the distribution volume of hydrophilic antimicrobials. The aim of this study was to investigate the relationships of PVPI and EVLWI with the distribution volume of vancomycin (Vss), as well as to establish a method for estimating Vss for planning an appropriate initial dose for individual patients. Seven patients were administered vancomycin intravenously and underwent extended hemodynamic monitoring with the PiCCO system in the intensive care unit (ICU) from April 2009 to March 2011. Vss was calculated using the Bayesian method, and the relationships of PVPI and EVLWI with Vss were investigated. The relationship between Vss/actual body weight (ABW) and median EVLWI on days when blood levels were measured was significant (r = 0.900, p = 0.0057), whereas the relationship between Vss/ABW and PVPI was not significant (r = 0.649, p = 0.1112). EVLWI determined by the PiCCO system is useful to predict Vss and should lead to more effective vancomycin therapy for critically ill patients at the initial stage.

  20. Determine the permeability of an amorphous mixture of polydimethylsiloxane and dealuminated zeolite ZSM-5 to various ethanol-water solutions using molecular simulations.

    EPA Science Inventory

    An amorphous mixture of PDMS and multi-cellular fragments of ZSM-5 is brought together to approximate the properties of a mixed matrix membrane of PDMS with ZSM-5. The permeability coefficient of the amorphous mixture for pure water is the product of the diffusion coefficient of...

  1. Determine the permeability of an amorphous mixture of polydimethylsiloxane and dealuminated zeolite ZSM-5 to various ethanol-water solutions using molecular simulations.

    EPA Science Inventory

    An amorphous mixture of PDMS and multi-cellular fragments of ZSM-5 is brought together to approximate the properties of a mixed matrix membrane of PDMS with ZSM-5. The permeability coefficient of the amorphous mixture for pure water is the product of the diffusion coefficient of...

  2. CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 1 PERFORMANCE EVALUATIONS AT TWO SITES

    EPA Science Inventory

    The purpose of this document is to provide detailed performance monitoring data on full-scale Permeable Reactive Barriers (PRBs) installed to treat contaminated ground water at two different sites. This report will fill a need for a readily available source of information for si...

  3. CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 1 PERFORMANCE EVALUATIONS AT TWO SITES

    EPA Science Inventory

    The purpose of this document is to provide detailed performance monitoring data on full-scale Permeable Reactive Barriers (PRBs) installed to treat contaminated ground water at two different sites. This report will fill a need for a readily available source of information for si...

  4. Leaf cuticular lipids on the Shandong and Yukon ecotypes of saltwater cress, eutrema salsugineum, and their response to water deficiency and impact on cuticle permeability

    USDA-ARS?s Scientific Manuscript database

    The impact of water deficit stress on leaf cuticular waxes and cutin monomers, and traits associated with cuticle permeability, were examined in Shandong and Yukon ecotypes of Eutrema salsugineum (syn. Thellungiella salsuginea). Although Shandong exhibits glaucous leaves, and Yukon is non-glaucous, ...

  5. GROUND WATER REMEDIATION OF CHROMIUM USING ZERO-VALENT IRON IN A PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of ...

  6. GROUND WATER REMEDIATION OF CHROMIUM USING ZERO-VALENT IRON IN A PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of ...

  7. Effect of rice wax on water vapor permeability and sorption properties of edible pullulan films

    USDA-ARS?s Scientific Manuscript database

    Edible pullulan films were prepared by substituting the pullulan with various ratios of rice wax. Freestanding composite films were obtained with up to 50% rice wax. Water vapor barrier properties of the film were improved with increased addition of the rice wax. Moisture sorption isotherms were ...

  8. HIGH PERMEABILITY MEMBRANES FOR THE DEHYDRATION OF LOW WATER CONTENT ETHANOL BY PERVAPORATION

    EPA Science Inventory

    Energy efficient dehydration of low water content ethanol is a challenge for the sustainable production of fuel-grade ethanol. Pervaporative membrane dehydration using a recently developed hydrophilic polymer membrane formulation consisting of a cross-linked mixture of poly(allyl...

  9. HIGH PERMEABILITY MEMBRANES FOR THE DEHYDRATION OF LOW WATER CONTENT ETHANOL BY PERVAPORATION

    EPA Science Inventory

    Energy efficient dehydration of low water content ethanol is a challenge for the sustainable production of fuel-grade ethanol. Pervaporative membrane dehydration using a recently developed hydrophilic polymer membrane formulation consisting of a cross-linked mixture of poly(allyl...

  10. The permeability variations on the Wenchuan Fault measured on the water level response to solid Earth tides

    NASA Astrophysics Data System (ADS)

    Xue, L.; Brodsky, E. E.; Li, H.; Wang, H.; Pei, J.

    2011-12-01

    The mechanics of slip during an earthquake depends critically on the hydrologic properties. The in situ fault zone hydrological properties are difficult to measure and have never directly been constrained on the fault zone immediately after a large earthquake. In this work, we analyze 1.5 years of continuous data from the Wenchuan Fault Zone which was the site of the Mw 7.9 Wenchuan earthquake. By using the solid Earth tides response we can constrain the average hydraulic properties of the damage zone at 800-1200 m below the surface (~200-600 m from the principal slip zone). We find that the hydraulic diffusivity D of Wenchuan Fault Zone is 0.03 m2/s, which is three orders of magnitude larger than pump test values on the Chelungpu Fault which is the site of the Mw 7.6 Chi-Chi earthquake. This measurement at Wenchuan was made by continuously monitoring the response of the well to the solid Earth tides. The solid earth tides impose a dilatational strain on the formation that pumps water cyclically in and out of the well. By measuring the phase and amplitude response, we can infer the transmissivity and storage near the fault assuming an isotropic, homogeneous and laterally extensive aquifer. We evaluated the phase and amplitude responses for solid Earth tide in both frequency domain and time domain. In the frequency domain analysis, we divide Fourier transform of the water levels by that of a synthetic tide to get the amplitude response and phase shift of the water level relative to the dilatational strain at the frequency of the largest semidiurnal tide M2. In the time domain, we use a least-square fit of prediction tidal harmonics to the water levels. Then we solve for phase and amplitude response at the frequency for M2. These two separate methods yield almost identical results. The average phase lag is ~ 25 degree, and the average amplitude response is 6×10-7 strain/m. According to the Heish model, we solve for storage coefficient S 2.2×10-4 and transmissivity

  11. [Effect of oral fluid resuscitation on pulmonary vascular permeability and lung water content in burn dogs in shock stage].

    PubMed

    Hu, Sen; Che, Jin-Wei; Tian, Yi-Jun

    2009-06-01

    To investigate the effect of oral fluid resuscitation on pulmonary vascular permeability and lung water content in burn dogs during shock stage. Eighteen male Beagle dogs with catheterization of carotid artery and jugular vein for 24 hours were subjected to 50% TBSA full-thickness burn, then they were divided into non-fluid resuscitation (NR), oral fluid resuscitation (OR), intravenous fluid resuscitation (IR) groups, with 6 dogs in each group. Dogs in OR and IR groups were given glucose-electrolyte solution (GES) by gastric tube or intravenous infusion according to Parkland formula within 24 hours after burn, while those in NR group were not given any treatment. Dogs in each group were then given intravenous fluid for further resuscitation after 24 post burn hours (PBH). Deaths were recorded within 72 hours after burn. Mean arterial pressure (MAP), respiratory rate (RR), PaO2, extravascular lung water index (ELWI) and pulmonary vascular permeability index (PVPI) were determined before burn and at 30 mins and 4, 8, 24, 48, 72 PBH with the aid of PICCO. Dogs were sacrificed to collect lung tissue for determination of water content at 72 PBH or just before death. All dogs died during 9-22 PBH in NR group, 3 dogs died during 25-47 PBH in OR group, and all dogs survived within 72 PBH in IR groups. Compared with those before burn, RR (44.0 +/- 5.0) times/min, ELWI (10.3 +/- 0.6) mL/kg and PVPI (6.6 +/- 0.6) were markedly increased in NR group at 8 PBH, but PaO2 and MAP were obviously decreased (P < 0.05). In OR group, RR (33.0 +/- 4.0) times/min, ELWI (8.9 +/- 0.3) mL/kg and PVPI (5.7 +/- 0.4) were significantly lower than those of NR group (P < 0.05), but higher than those of IR group [RR (26.0 +/- 3.0) times/min, ELWI (8.2 +/-0.3) mL/kg, PVPI (4.2 +/- 0.4), P < 0.05] at 8 PBH. PaO2 and MAP in OR group were higher than that in NR group (P < 0.05). Lung water content showed no statistically significant difference between OR ang IR groups (P > 0.05), which were lower

  12. All-trans-retinoic acid regulates aquaporin-3 expression and related cellular membrane permeability in the human amniotic environment.

    PubMed

    Prat, C; Bouvier, D; Comptour, A; Marceau, G; Belville, C; Clairefond, G; Blanc, P; Gallot, D; Blanchon, L; Sapin, V

    2015-08-01

    The aquaporins (AQP1, 3, 8, 9 and 11) are known to be expressed, and involved in the transport of water and small molecules through fetal membranes. To exert these crucial functions, these AQPs have to be finely regulated. All-trans-retinoic acid (atRA) was previously found to regulate some genes in this environment, raising the question of whether these AQPs were regulated by atRA. Explants, and primary and established amniotic cells were cultured to determine which AQP were transcriptionally modified by atRA, using the qRT-PCR strategy. Immunohistochemistry and glycerol uptake tests were used to determine the impact of atRA on AQP protein expression and function. Specific agonists of retinoic acid receptors were used to identify the molecular mechanisms of AQP promoter activation. A classical gene AQP promoter study was also used to identify DR5 retinoic acid receptor elements (RAREs). Beyond these AQPs, only one specific atRA-dependent increase in AQP3 transcripts and proteins level was established in amnion (not in chorion) and in related primary and established cells. We found three DR5-RAREs essential for inducing this transcriptional AQP3 through RARα. This transactivation of the AQP3 coding gene was functionally related to an increase of AQP3 permeability tests by a glycerol uptake assay. Our data support an atRA regulatory model of AQP3 expression leading to an increased cellular permeability in the epithelial amniotic environment. We cast new light on AF regulation in healthy pregnancy, and advance new hypotheses for obstetrical complications linked to impairment of the retinoic signaling pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Transepithelial water and urea permeabilities of isolated perfused Munich-Wistar rat inner medullary thin limbs of Henle's loop

    PubMed Central

    Nawata, C. Michele; Evans, Kristen K.; Dantzler, William H.

    2013-01-01

    To better understand the role that water and urea fluxes play in the urine concentrating mechanism, we determined transepithelial osmotic water permeability (Pf) and urea permeability (Purea) in isolated perfused Munich-Wistar rat long-loop descending thin limbs (DTLs) and ascending thin limbs (ATLs). Thin limbs were isolated either from 0.5 to 2.5 mm below the outer medulla (upper inner medulla) or from the terminal 2.5 mm of the inner medulla. Segment types were characterized on the basis of structural features and gene expression levels of the water channel aquaporin 1, which was high in the upper DTL (DTLupper), absent in the lower DTL (DTLlower), and absent in ATLs, and the Cl-1 channel ClCK1, which was absent in DTLs and high in ATLs. DTLupper Pf was high (3,204.5 ± 450.3 μm/s), whereas DTLlower showed very little or no osmotic Pf (207.8 ± 241.3 μm/s). Munich-Wistar rat ATLs have previously been shown to exhibit no Pf. DTLupper Purea was 40.0 ± 7.3 × 10−5 cm/s and much higher in DTLlower (203.8 ± 30.3 × 10−5 cm/s), upper ATL (203.8 ± 35.7 × 10−5 cm/s), and lower ATL (265.1 ± 49.8 × 10−5 cm/s). Phloretin (0.25 mM) did not reduce DTLupper Purea, suggesting that Purea is not due to urea transporter UT-A2, which is expressed in short-loop DTLs and short portions of some inner medullary DTLs close to the outer medulla. In summary, Purea is similar in all segments having no osmotic Pf but is significantly lower in DTLupper, a segment having high osmotic Pf. These data are inconsistent with the passive mechanism as originally proposed. PMID:24197065

  14. Sex-dependent changes in blood-brain barrier permeability and brain NA(+),K(+) ATPase activity in rats following acute water intoxication.

    PubMed

    Oztaş, B; Koçak, H; Oner, P; Küçük, M

    2000-12-01

    To understand the increased susceptibility of the development of serious complications to hypoosmotic hyponatremia in young females, we examined the resistance of blood brain barrier (BBB) permeability to water along with the synaptosomal Na(+),K(+)ATPase activity in both sexes of rats during acute water intoxication. Four groups of rats were used: Group I and II were normal female and male rats injected with only Evans-blue. Group III and IV were water intoxicated female and male rats respectively. BBB permeability in female rats was found to be increased following acute water intoxication. In contrast, synaptosomal Na(+),K(+)ATPase activities in both water intoxicated male and female rats were found significantly lower than those in control rats. But inhibition in enzyme activity in synaptosomes from water intoxicated female rats was more pronounced than those of corresponding male rats. Our results concluded that female sex steroids may be responsible for the highly significant decrease in synaptosomal Na(+),K(+)ATPase activity and increased BBB permeability in female rats following water intoxication.

  15. Non-invasive imaging using reporter genes altering cellular water permeability

    NASA Astrophysics Data System (ADS)

    Mukherjee, Arnab; Wu, Di; Davis, Hunter C.; Shapiro, Mikhail G.

    2016-12-01

    Non-invasive imaging of gene expression in live, optically opaque animals is important for multiple applications, including monitoring of genetic circuits and tracking of cell-based therapeutics. Magnetic resonance imaging (MRI) could enable such monitoring with high spatiotemporal resolution. However, existing MRI reporter genes based on metalloproteins or chemical exchange probes are limited by their reliance on metals or relatively low sensitivity. Here we introduce a new class of MRI reporters based on the human water channel aquaporin 1. We show that aquaporin overexpression produces contrast in diffusion-weighted MRI by increasing tissue water diffusivity without affecting viability. Low aquaporin levels or mixed populations comprising as few as 10% aquaporin-expressing cells are sufficient to produce MRI contrast. We characterize this new contrast mechanism through experiments and simulations, and demonstrate its utility in vivo by imaging gene expression in tumours. Our results establish an alternative class of sensitive, metal-free reporter genes for non-invasive imaging.

  16. Non-invasive imaging using reporter genes altering cellular water permeability.

    PubMed

    Mukherjee, Arnab; Wu, Di; Davis, Hunter C; Shapiro, Mikhail G

    2016-12-23

    Non-invasive imaging of gene expression in live, optically opaque animals is important for multiple applications, including monitoring of genetic circuits and tracking of cell-based therapeutics. Magnetic resonance imaging (MRI) could enable such monitoring with high spatiotemporal resolution. However, existing MRI reporter genes based on metalloproteins or chemical exchange probes are limited by their reliance on metals or relatively low sensitivity. Here we introduce a new class of MRI reporters based on the human water channel aquaporin 1. We show that aquaporin overexpression produces contrast in diffusion-weighted MRI by increasing tissue water diffusivity without affecting viability. Low aquaporin levels or mixed populations comprising as few as 10% aquaporin-expressing cells are sufficient to produce MRI contrast. We characterize this new contrast mechanism through experiments and simulations, and demonstrate its utility in vivo by imaging gene expression in tumours. Our results establish an alternative class of sensitive, metal-free reporter genes for non-invasive imaging.

  17. Carbonate Microfabrics Permeability Characteristics of Continental Slope and Deep-Water Carbonates from a Microfabric Perspective

    DTIC Science & Technology

    1994-01-01

    the Precipitation of fine- algal remnants, pteropods, coccoliths, foraminifers , sponge grimed magnesian calcite in the Bahamas. Roberts and spicules...volumes of authigenic deep-water carbonate constituents am planktonic foraminifers carbonates. Some of the authigenic carbonates described by and...such as pteropods (500 to 1000 pm) and foraminifers (50 to 100 am). Samples from the slopes of Exuma Sound were more frequently matrix supported, with

  18. Visible study of water shutoff techniques for reservoirs with high permeability channels

    NASA Astrophysics Data System (ADS)

    Xin, Yanyong; Zhao, Xuan

    2017-05-01

    This paper describes a compound-linking gel system consisting of Polymer, Chromium (+3), Phenolic resin and rubber particles, which has good performance for water blocking. Indoor experiments demonstrate that the breaking through pressure of compound gel system is 4.92 MPa/m, which is much higher than 2.5-3 MPa/m of conventional, and its flooding resistance is better. The pressure of sand-pack with compound gel system reaches stability at 2.5MPa after 7PV water flooding while others stay at 1.1-1.6 MPa after 3-4PV water displacement. Visible flooding models are developed to optimize the injection volume and investigate the best location to deploy plugging agents. The results show that there is a limit on injection volume, and when it equals to 0.1-0.2 PV, the application may have economic success. For models with worm-shaped channels, the best location for plugging agents is just after “inflection point” near injecting well, which can make full use of the fluid diverting to achieve highest oil recovery.

  19. Improved method for measuring water imbibition rates on low-permeability porous media

    USGS Publications Warehouse

    Humphrey, M.D.; Istok, J.D.; Flint, L.E.; Flint, A.L.

    1996-01-01

    Existing methods for measuring water imbibition rates are inadequate when imbibition rates are small (e.g., clay soils and many igneous rocks). We developed an improved laboratory method for performing imbibition measurements on soil or rock cores with a wide range of hydraulic properties. Core specimens are suspended from an electronic strain gauge (load cell) in a closed chamber while maintaining the lower end of the core in contact with a free water surface in a constant water level reservoir. The upper end of the core is open to the atmosphere. During imbibition, mass increase of the core is recorded continuously by a datalogger that converts the load cell voltage signal into mass units using a calibration curve. Computer automation allows imbibition rate measurement on as many as eight cores simultaneously and independently. Performance of each component of the imbibition apparatus was evaluated using a set of rock cores (2.5 cm in diameter and 2-5 cm in length) from a single lithostratigraphic unit composed of non-to-moderately welded ash-flow tuff (a glass-rich pyroclastic rock partially fused by heat and pressure) with porosities ranging from 0.094 to 0.533 m3 m-3. Reproducibility of sample handling and testing procedures was demonstrated using replicate measurements. Precision and accuracy of load cell measurements were assessed using mass balance calculations and indicated agreement within a few tenths of a percent of total mass. Computed values of sorptivity, S, ranged from 8.83 x 10-6 to 4.55 x 10-4 m s-0.5. The developed method should prove useful for measuring imbibition rates on a wide range of porous materials.

  20. Morphometric analysis of oleic acid-induced permeability pulmonary edema: correlation with gravimetric lung water.

    PubMed

    Darien, B J; Saban, M R; Hart, A P; MacWilliams, P S; Clayton, M K; Kruse-Elliott, K T

    1997-07-01

    The technique used most commonly to quantitate pulmonary edema in in vivo animal models is postmortem gravimetric analysis (wet:dry) ratio. To determine whether lung water can be quantitated morphometrically, as accurately as by the commonly used gravimetric analysis, perivascular edema (cuff) area to vessel area ratio was correlated to wet:dry ratio. Anesthetized pigs were given either oleic acid (20 mg/kg/h, intravenously) or physiologic saline. At 4 h, lungs were excised and cuff:vessel and wet:dry ratio analysis was performed. The intermediate lobe was clamped across its main stem bronchus to maintain peak inspiratory inflation, excised, frozen in liquid nitrogen, and stored at -70 degrees C until cryostat sectioning and quantification of perivascular interstitial edema (cuff) area. Gravimetric analysis (wet:dry ratio) was performed on the remaining lung. Mean cuff:vessel and wet:dry analyzes showed that lung water increased significantly (p < .01) in the oleic-acid treated group (4.9 +/- .22 and 6.78 +/- .47, respectively), compared with the saline group (.03 +/- .02 and 2.55 +/- .27, respectively). The correlation coefficient between mean cuff:vessel and wet:dry ratios was .86 (p = .0016). This study demonstrates that cuff:vessel ratio analysis can be used to identify the distribution of edema fluid versus vessel diameter, and seems to be as effective a technique as gravimetric analysis to quantitate lung water changes in acute lung injury models. Moreover cuff:vessel ratio analysis can differentiate modest changes in pulmonary edema by direct quantitation, an important end-point not provided by wet:dry analysis. Therefore, it may be a more sensitive technique when investigating therapeutic interventions in in vivo models of acute lung injury.

  1. Non-invasive imaging using reporter genes altering cellular water permeability

    PubMed Central

    Mukherjee, Arnab; Wu, Di; Davis, Hunter C.; Shapiro, Mikhail G.

    2016-01-01

    Non-invasive imaging of gene expression in live, optically opaque animals is important for multiple applications, including monitoring of genetic circuits and tracking of cell-based therapeutics. Magnetic resonance imaging (MRI) could enable such monitoring with high spatiotemporal resolution. However, existing MRI reporter genes based on metalloproteins or chemical exchange probes are limited by their reliance on metals or relatively low sensitivity. Here we introduce a new class of MRI reporters based on the human water channel aquaporin 1. We show that aquaporin overexpression produces contrast in diffusion-weighted MRI by increasing tissue water diffusivity without affecting viability. Low aquaporin levels or mixed populations comprising as few as 10% aquaporin-expressing cells are sufficient to produce MRI contrast. We characterize this new contrast mechanism through experiments and simulations, and demonstrate its utility in vivo by imaging gene expression in tumours. Our results establish an alternative class of sensitive, metal-free reporter genes for non-invasive imaging. PMID:28008959

  2. An evaluation of the relative roles of the unstirred water layer and receptor sink in limiting the in-vitro intestinal permeability of drug compounds of varying lipophilicity.

    PubMed

    Katneni, Kasiram; Charman, Susan A; Porter, Christopher J H

    2008-10-01

    The roles of the unstirred water layer (UWL) and receptor sink on the in-vitro transmembrane permeability of an increasingly lipophilic series of compounds (mannitol (MAN), diazepam (DIA) and cinnarizine (CIN)) have been assessed. Altered carbogen bubbling rates were used as a means to change the UWL thickness and polysorbate-80 (PS-80), bovine serum albumin (BSA) and alpha-1-acid glycoprotein (AAG) were employed to alter sink conditions. After correction for solubilisation, Papp data for MAN, DIA and CIN were consistent across varying donor PS-80 concentrations suggesting that for the drugs examined here, the donor UWL did not limit in-vitro permeability. Similarly, altered bubbling rates and receptor sink conditions had no impact on the permeability of MAN. In contrast, decreasing the size of the receptor UWL or adding solubilising agents to the receptor sink resulted in modest enhancements to the permeability of the more lipophilic probe DIA. For the most lipophilic compound, CIN, very significant changes to measured permeability (>30 fold) were possible, but were most evident only after concomitant changes to both the UWL and sink conditions, suggesting that the effectiveness of enhanced sink conditions were dependent on a decrease in the width of the UWL.

  3. Using earth-tide induced water pressure changes to measure in situ permeability: A comparison with long-term pumping tests

    NASA Astrophysics Data System (ADS)

    Allègre, Vincent; Brodsky, Emily E.; Xue, Lian; Nale, Stephanie M.; Parker, Beth L.; Cherry, John A.

    2016-04-01

    Good constraints on hydrogeological properties are an important first step in any quantitative model of groundwater flow. Field estimation of permeability is difficult as it varies over orders of magnitude in natural systems and is scale-dependent. Here we directly compare permeabilities inferred from tidal responses with conventional large-scale, long-term pumping tests at the same site. Tidally induced water pressure changes recorded in wells are used to infer permeability at ten locations in a densely fractured sandstone unit. Each location is either an open-hole well or a port in a multilevel monitoring well. Tidal response is compared at each location to the results of two conventional, long-term and large scale pumping tests performed at the same site. We obtained consistent values between the methods for a range of site-specific permeabilities varying from ˜10-15 m2 to 10-13 m2 for both open wells with large open intervals and multilevel monitoring well. We conclude that the tidal analysis is able to capture passive and accurate estimates of permeability.

  4. The role of ABA and the transpiration stream in the regulation of the osmotic water permeability of leaf cells

    PubMed Central

    Morillon, Raphaël; Chrispeels, Maarten J.

    2001-01-01

    The transpiration stream that passes through a plant may follow an apoplastic route, with low resistance to flow, or a cell-to-cell route, in which cellular membranes impede water flow. However, passage of water through membranes can be facilitated by aquaporins thereby decreasing resistance. We investigated the relationship between transpiration, which can be down-regulated by abscisic acid (ABA) or by high humidity, and the osmotic water permeability (Pos) of protoplasts. By using leaf protoplasts of wild-type (wt) Arabidopsis thaliana plants and of mutants that are low in ABA (aba1) or insensitive to ABA (abi1 and abi2), we found that protoplasts from aba1 and abi mutants have very low Pos values compared with those from wt plants when the plants are grown at 45% relative humidity. High values of Pos were found 3 h after the addition of ABA to the culture medium of aba1 plants; addition of ABA to abi plants did not restore the Pos to wt levels. There was no such increase in Pos when excised leaves of aba1 plants were treated with ABA. When the transpiration stream was attenuated by growing the plants at 85% relative humidity, the Pos of protoplasts from all plants (wt and mutants) was higher. We suggest that attenuation of the transpiration stream in whole plants is required for the up-regulation of the Pos of the membranes, and that this up-regulation, which does not require ABA, is mediated by the activation of aquaporins in the plasma membrane. PMID:11707572

  5. In vivo silencing of aquaporin-1 by RNA interference inhibits angiogenesis in the chick embryo chorioallantoic membrane assay.

    PubMed

    Camerino, G M; Nicchia, G P; Dinardo, M M; Ribatti, D; Svelto, M; Frigeri, A

    2006-10-30

    Aquaporin-1 (AQP1) is a water channel protein mainly expressed in endothelial and epithelial cells of many tissues, including the vasculature where it serves to increase cell membrane water permeability. Previous studies in active multiple myeloma patients and in AQP1 KO mice indicated an involvement of AQP1 in physiological and tumor angiogenesis. To understand the physiological role of AQP1 in angiogenesis, we used a 21-nucleotide small interfering RNA duplexes (siRNA) to knockdown AQP1 in the chick embryo chorioallantoic membrane (CAM), a commonly used in vivo assay to study both angiogenic and angiostatic molecules. Chicken AQP1 sequence was identified and utilized to synthesize a siRNA directed to the AQP1 sequence. We then tested the efficiency of the siRNA in vitro, using an AQP1 transfected cell line. The level of AQP1 protein reduction obtained using siRNA was 98 % and 92 % after 1 and 2 day transfection respectively. RNA interference experiments were then performed in vivo by using the CAM assay. Results showed that after 4 days of treatment, AQP1 siRNA was able to strongly inhibit angiogenesis. This is the first study showing the in vivo use of RNA interference technique in the CAM assay. Our results strongly support the hypothesis that AQP1 could have a key role in physiological and pathological angiogenesis.

  6. Effect of adhesive hydrophilicity and curing-time on the permeability of resins bonded to water vs. ethanol-saturated acid-etched dentin

    PubMed Central

    Cadenaro, Milena; Breschi, Lorenzo; Rueggeberg, Frederick A.; Agee, Kelli; Di Lenarda, Roberto; Carrilho, Marcela; Tay, Franklin R.; Pashley, David H.

    2009-01-01

    Objective This study examined the ability of five comonomer blends (R1-R5) of methacrylate-based experimental dental adhesives solvated with 10 mass% ethanol, at reducing the permeability of acid-etched dentin. The resins were light-cured for 20, 40 or 60 s. The acid-etched dentin was saturated with water or 100% ethanol. Method Human unerupted third molars were converted into crown segments by removing the occlusal enamel and roots. The resulting crown segments were attached to plastic plates connected to a fluid-filled system for quantifying fluid flow across smear layer-covered dentin, acid-etched dentin and resin-bonded dentin. The degree of conversion of the resins was measured using Fourier transform infrared spectroscopy. Result Application of the most hydrophobic comonomer blend (R1) to water-saturated dentin produced the smallest reductions in dentin permeability (31.9, 44.1 and 61.1% after light-curing for 20, 40 or 60 s respectively). Application of the same blend to ethanol-saturated dentin reduced permeability of 74.1, 78.4 and 81.2%, respectively (p<0.05). Although more hydrophilic resins produced larger reductions in permeability, the same trend of significantly greater reductions in ethanol-saturated dentin over that of water-saturated dentin remained. This result can be explained by the higher solubility of resins in ethanol vs. water. Significance The largest reductions in permeability produced by resins were equivalent but not superior, to those produced by smear layers. Resin sealing of dentin remains a technique-sensitive step in bonding etch-and-rinse adhesives to dentin. PMID:18571228

  7. An Experimental Study of CO2 Exsolution and Relative Permeability Measurements during CO2 Saturated Water Depressurization Relevant to Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Zuo, L.; Krevor, S. C.; Falta, R. W.; Benson, S. M.

    2011-12-01

    Saline aquifers and depleted oil and gas fields have been considered as preferred geological sequestration options for carbon dioxide to reduce greenhouse gas emissions. Given the high solubility of CO2 in water, over time, the fraction of CO2 in the subsurface may be dominated by dissolved CO2. CO2 laden brine may permeate cap rocks and carry dissolved CO2 to shallower depths, if there is an upward pressure gradient from the reservoir to the overlying groundwater aquifers. This kind of non-hydrostatic pressure gradients can be caused by gas injection in deeper formations, or groundwater depletion. Such upward flows will depressurize the brine and the dissolved CO2 will come out of solution as pressure drops. We present the results of an experimental investigation into the effects of CO2 exsolution on multiphase flow properties in a CO2-water system with various reservoir rocks and a risk assessment of CO2 leakage due to exsolution in carbon sequestration. The relative permeability of exsolved CO2 and water was measured in a core-flooding apparatus during depressurization with X-ray computed tomography. Very low relative permeabilities of CO2 and water are measured in the exsolution experiments, compared to the relative permeabilities derived from steady-state drainage measurements in the same cores, even when the CO2 saturation is as high as 40%. The large relative permeability reduction in both the CO2 and water phases is hypothesized to result from the presence of a disconnected exsolution gas phase in this flow system. After the CO2 was exsolved, a CO2-saturated water flooding experiment demonstrated the durability and the stability of the low water mobility in the presence of the exsolution gas phase, while the water mobility returned to normal after all of the exsolved CO2 dissolved by a fresh water. A large pressure drop across the core, which is 4~5 times higher than the pressure drop predicted by the drainage relative permeability, was maintained over 120

  8. Measurement of absolute cell volume, osmotic membrane water permeability, and refractive index of transmembrane water and solute flux by digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Boss, Daniel; Kühn, Jonas; Jourdain, Pascal; Depeursinge, Christian; Magistretti, Pierre J.; Marquet, Pierre

    2013-03-01

    A dual-wavelength digital holographic microscope to measure absolute volume of living cells is proposed. The optical setup allows us to reconstruct two quantitative phase contrast images at two different wavelengths from a single hologram acquisition. When adding the absorbing dye fast green FCF as a dispersive agent to the extracellular medium, cellular thickness can be univocally determined in the full field of view. In addition to the absolute cell volume, the method can be applied to derive important biophysical parameters of living cells including osmotic membrane water permeability coefficient and the integral intracellular refractive index (RI). Further, the RI of transmembrane flux can be determined giving an indication about the nature of transported solutes. The proposed method is applied to cultured human embryonic kidney cells, Chinese hamster ovary cells, human red blood cells, mouse cortical astrocytes, and neurons.

  9. Sevenfold-reduced osmotic water permeability in primary astrocyte cultures from AQP-4-deficient mice, measured by a fluorescence quenching method.

    PubMed

    Solenov, Eugen; Watanabe, Hiroyuki; Manley, Geoffrey T; Verkman, A S

    2004-02-01

    A calcein fluorescence quenching method was applied to measure osmotic water permeability in highly differentiated primary cultures of brain astrocytes from wild-type and aquaporin-4 (AQP-4)-deficient mice. Cells grown on coverglasses were loaded with calcein for measurement of volume changes after osmotic challenge. Hypotonic shock producing twofold cell swelling resulted in a reversible approximately 12% increase in calcein fluorescence, which was independent of cytosolic calcein concentration at levels well below where calcein self-quenching occurs. Calcein fluorescence was quenched in <200 ms in response to addition of cytosol in vitro, indicating that the fluorescence signal arises from changes in cytosol concentration. In astrocytes from wild-type CD1 mice, calcein fluorescence increased reversibly in response to hypotonic challenge with a half-time of 0.92 +/- 0.05 s at 23 degrees C, corresponding to an osmotic water permeability (Pf) of approximately 0.05 cm/s. Pf was reduced 7.1-fold in astrocytes from AQP-4-deficient mice. Temperature dependence studies indicated an increased Arrhenius activation energy for water transport in AQP-4-deficient astrocytes (11.3 +/- 0.5 vs. 5.5 +/- 0.4 kcal/mol). Our studies establish a calcein quenching method for measurement of cell membrane water permeability and indicate that AQP-4 provides the principal route for water transport in astrocytes.

  10. β-Cyclodextrin and permeability to water in the bladder of Bufo arenarum.

    PubMed

    Orce, G; Castillo, G; Chanampa, Y

    2011-05-01

    We measured the effect of β-cyclodextrin (BCD, a cholesterol scavenger) on water flow across the isolated toad bladder exposed to an osmotic gradient (J(w)) by a gravimetric technique. BCD, when present in the solution bathing the apical side of the bladder, inhibited the increase in J(w) caused by nystatin, a polyene antibiotic that acts by directly binding apical membrane cholesterol. When present in the basolateral bath, BCD inhibited the increase in J(w) caused by basolateral exposure to oxytocin (which binds membrane receptors and stimulates the synthesis of cAMP), but did not alter the response to theophylline (which inhibits hydrolysis of cAMP by cyclic nucleotide phosphodiesterase). The present data are consistent with the notion that agents that increase J(w) by interacting with membrane receptors, which appear to be clustered in cholesterol-rich domains of the basolateral membrane, are altered by cholesterol depletion, whereas agents that do not interact with receptors or other basolateral membrane components are not affected by this treatment. In either case, cholesterol depletion of the apical membrane does not affect the increase in J(w) brought about by an increase in intracellular cAMP concentration.

  11. Seismic waves increase permeability.

    PubMed

    Elkhoury, Jean E; Brodsky, Emily E; Agnew, Duncan C

    2006-06-29

    Earthquakes have been observed to affect hydrological systems in a variety of ways--water well levels can change dramatically, streams can become fuller and spring discharges can increase at the time of earthquakes. Distant earthquakes may even increase the permeability in faults. Most of these hydrological observations can be explained by some form of permeability increase. Here we use the response of water well levels to solid Earth tides to measure permeability over a 20-year period. At the time of each of seven earthquakes in Southern California, we observe transient changes of up to 24 degrees in the phase of the water level response to the dilatational volumetric strain of the semidiurnal tidal components of wells at the Piñon Flat Observatory in Southern California. After the earthquakes, the phase gradually returns to the background value at a rate of less than 0.1 degrees per day. We use a model of axisymmetric flow driven by an imposed head oscillation through a single, laterally extensive, confined, homogeneous and isotropic aquifer to relate the phase response to aquifer properties. We interpret the changes in phase response as due to changes in permeability. At the time of the earthquakes, the permeability at the site increases by a factor as high as three. The permeability increase depends roughly linearly on the amplitude of seismic-wave peak ground velocity in the range of 0.21-2.1 cm s(-1). Such permeability increases are of interest to hydrologists and oil reservoir engineers as they affect fluid flow and might determine long-term evolution of hydrological and oil-bearing systems. They may also be interesting to seismologists, as the resulting pore pressure changes can affect earthquakes by changing normal stresses on faults.

  12. Neuromyelitis Optica Immunoglobulin G present in sera from neuromyelitis optica patients affects aquaporin-4 expression and water permeability of the astrocyte plasma membrane.

    PubMed

    Melamud, Luciana; Fernández, Juan M; Rivarola, Valeria; Di Giusto, Gisela; Ford, Paula; Villa, Andrés; Capurro, Claudia

    2012-06-01

    NMO-IgG autoantibody selectively binds to aquaporin-4 (AQP4), the most abundant water channel in the central nervous system and is now considered a useful serum biomarker of neuromyelitis optica (NMO). A series of clinical and pathological observations suggests that NMO-IgG may play a central role in NMO physiopathology. The current study evaluated, in well-differentiated astrocytes cultures, the consequences of NMO-IgG binding on the expression pattern of AQP4 and on plasma membrane water permeability. To avoid or to facilitate AQP4 down-regulation, cells were exposed to inactivated sera in two different situations (1 hr at 4°C or 12 hr at 37°C). AQP4 expression was detected by immunofluorescence studies using a polyclonal anti-AQP4 or a human anti-IgG antibody, and the water permeability coefficient was evaluated by a videomicroscopy technique. Our results showed that, at low temperatures, cell exposure to either control or NMO-IgG sera does not affect either AQP4 expression or plasma membrane water permeability, indicating that the simple binding of NMO-IgG does not affect the water channel's activity. However, at 37°C, long-term exposure to NMO-IgG induced a loss of human IgG signal from the plasma membrane along with M1-AQP4 isoform removal and a significant reduction of water permeability. These results suggest that binding of NMO-IgG to cell membranes expressing AQP4 is a specific mechanism that may account for at least part of the pathogenic process. Copyright © 2012 Wiley Periodicals, Inc.

  13. Novel additives to retard permeable flow

    SciTech Connect

    Golombok, Michael; Crane, Carel; Ineke, Erik; Welling, Marco; Harris, Jon

    2008-09-15

    Low concentrations of surfactant and cosolute in water, can selectively retard permeable flow in high permeability rocks compared to low permeability ones. This represents a way forward for more efficient areal sweep efficiency when water flooding a reservoir during improved oil recovery. (author)

  14. LONG-TERM PERFORMANCE OF IN-SITU PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. The few pilot and commercial installations which have been implemented...

  15. Sexual maturation and changes in water and salt transport components in the kidney and intestine of three-spined stickleback (Gasterosteus aculeatus L.).

    PubMed

    Madsen, Steffen S; Weber, Claus; Nielsen, Andreas M; Mohiseni, Mohammad; Bosssus, Maryline C; Tipsmark, Christian K; Borg, Bertil

    2015-10-01

    Mature three-spined stickleback males use spiggin threads secreted from their kidney to glue together nest material. This requires strongly hypertrophied renal proximal tubular cells, which compromises renal osmoregulatory function during the breeding period. Experimental evidence suggests that the intestine takes over hypotonic fluid secretion at that stage but the mechanism is unexplored. To unravel the molecular mechanism we analyzed and compared transcript levels of several membrane proteins involved in water and salt transport in intestinal and renal tissues, in non-mature males (NM), mature males (MM), and mature females (MF). Aquaporin paralogs aqp1a, -3a, -8aa, -8ab, -10a, and -10b, two Na(+),K(+)-ATPase alpha-1 subunit isoforms (nka547, nka976), Na(+),K(+),2Cl(-)-, and Na(+),Cl(-)-cotransporters (nkcc1a, nkcc2, ncc), the cystic fibrosis transmembrane conductance regulator (cftr) and two claudin isoforms (cldn2, cldn15a) were expressed in the intestine and kidney in all groups. There were no differences in aqp and cldn expression between intestines of NM and MM; nkcc2 was lower and nka levels tended to be higher in intestines of MM than in NM. In the kidney, aqp1 and aqp8ab levels were lower in MM than in NM, whereas aqp3a, nkcc1a, cldn15a, and spiggin were markedly elevated. This was accompanied by marked hypertrophy of kidney tubules in MM. The data support an altered kidney function in terms of water handling in mature males, whereas there was no support for modified trans-epithelial water permeability or salt-secretory activity in the intestine of mature males. Salt-absorptive activity in the intestine may, however, be down-regulated during male maturation. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Studies on water transport through the sweet cherry fruit surface. 11. FeCl3 decreases water permeability of polar pathways.

    PubMed

    Weichert, Holger; Knoche, Moritz

    2006-08-23

    The effect of FeCl3 (10 mM) on osmotic water uptake into detached sweet cherry fruit (Prunus avium L.) and on the (3)H2O permeability (P(d)) of excised exocarp segments (ES) or enzymatically isolated cuticular membranes (CM) was investigated. ES or CM were mounted in an infinite dose diffusion system, where diffusion is monitored from a dilute donor solution through an interfacing ES or CM into a receiver solution under quasi steady-state conditions. In the absence of FeCl3, (3)H2O diffusion through stomatous ES was linear over time, indicating that P(d) was constant. Adding FeCl3 to the donor decreased P(d) by about 60%. P(d) remained at a decreased level when replacing the FeCl3 donor again by deionized water. The decrease in P(d) was positively and linearly related to the stomatal density of the ES. There was no effect of FeCl3 on the P(d) of astomatous sweet cherry fruit ES or CM regardless of the presence of wax (epicuticular or cuticular). FeCl3 decreased P(d) when added to the donor (-63%) or receiver (-16%), but there was no effect when it was added to donor and receiver solutions simultaneously. The decrease in P(d) depended on the pH of the receiver and the presence of citrate buffer. There was no effect of FeCl3 with citrate buffer as a receiver regardless of pH (range 2.0-6.0). When using nonbuffered receiver solutions with pH adjusted to pH 2.0, 3.0, 4.5, or 6.0, FeCl3 markedly decreased (3)H2O diffusion at pH > or = 3 but had no effect at pH 2.0. FeCl3 increased the energy of activation (E(a)) for (3)H2O diffusion (range 15-45 degrees C) through stomatous ES but had no significant effect in astomatous CM. The increase in E(a) by FeCl3 was positively related to stomatal density. FeCl3 decreased the P(d) for 2-(1-naphthyl)[1-(14)C]acetic acid (NAA) and 2,4-dichloro[U-(14)C]phenoxyacetic acid (2,4-D) in stomatous ES. The magnitude of the effect depended on the degree of dissociation and was larger for the dissociated acids (pH 6.2) than for the

  17. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  18. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  19. Laser-drilled micro-hole arrays on polyurethane synthetic leather for improvement of water vapor permeability

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Wang, A. H.; Zheng, R. R.; Tang, H. Q.; Qi, X. Y.; Ye, B.

    2014-06-01

    Three kinds of lasers at 1064, 532 and 355 nm wavelengths respectively were adopted to construct micro-hole arrays on polyurethane (PU) synthetic leather with an aim to improve water vapor permeability (WVP) of PU synthetic leather. The morphology of the laser-drilled micro-holes was observed to optimize laser parameters. The WVP and slit tear resistance of the laser-drilled leather were measured. Results show that the optimized pulse energy for the 1064, 532 and 355 nm lasers are 0.8, 1.1 and 0.26 mJ, respectively. The diameters of the micro-holes drilled with the optimized laser pulse energy were about 20, 15 and 10 μm, respectively. The depths of the micro-holes drilled with the optimized pulse energy were about 21, 60 and 69 μm, respectively. Compared with the untreated samples, the highest WVP growth ratio was 38.4%, 46.8% and 53.5% achieved by the 1064, 532 and 355 nm lasers, respectively. And the highest decreasing ratio of slit tear resistance was 11.1%, 14.8%, and 22.5% treated by the 1064, 532 and 355 nm lasers, respectively. Analysis of the interaction mechanism between laser beams at three kinds of laser wavelengths and the PU synthetic leather revealed that laser micro-drilling at 355 nm wavelength displayed both photochemical ablation and photothermal ablation, while laser micro-drilling at 1064 and 532 nm wavelengths leaded to photothermal ablation only.

  20. Chemical composition, water vapor permeability, and mechanical properties of yuba film influenced by soymilk depth and concentration.

    PubMed

    Zhang, Siran; Lee, Jaesang; Kim, Yookyung

    2017-09-01

    Yuba is a soy protein-lipid film formed during heating of soymilk. This study described yuba as an edible film by analyzing its chemical composition, water vapor permeability (WVP), and mechanical properties. Three yuba films were prepared by using different concentrations and depths of soymilk: HS (86 g kg(-1) and 2.3 cm), LS (70 g kg(-1) and 2.3 cm), and LD (70 g kg(-1) and 3.0 cm). As yuba was successively skimmed, the protein, lipid, and -SH content decreased, but carbohydrate and -S-S content increased. Even if both the initial concentration and the depth of soymilk affect the properties of the films, the depth of soymilk influences more WVP and tensile strength. The WVP of the HS and LS changed the least (13 to 17 g·mm/kPa·m(2) d), while that of the LD changed the most (13 to 35 gmm/kPa·m(2) d). There were no differences (p > 0.05) in the tensile strength (TS) between the HS and LS. LD had the greatest decrease of TS and the lowest TS among the groups. The earlier the yuba films were collected, the higher the elongation of the films was: 129% (HS), 113% (LS), and 155% (LD). The initial concentration and the depth of soymilk changed the chemical composition and structure of the yuba films. The LS yuba produced more uniform edible films with good mechanical properties. This article is protected by copyright. All rights reserved.

  1. Direct Microscale Measurement of Mouse Oocyte Membrane Permeability to Water and Ethylene Glycol at Subzero Temperatures Using Cryomicroscopy.

    PubMed

    Han, X

      BACKGROUND: Investigation of cell osmotic behavior at subzero temperatures is of critical importance to the optimization of cooling procedures for cryopreservation. Based on established thermodynamic models, plasma membrane permeability coefficients for water and cryoprotectant agent (CPA) (Lcpa, Pp) and their activation energies (Ea(Lp), Ea(Pcpa)) are essential to predict the change of cell volume and composition of intracellular solutions corresponding to different cooling procedures. However, currently available methods to measure Lp at subzero temperatures suffer from technical difficulties due to ice formation and there are no generalized methods to measure Pcpa at subzero temperatures. The present study aims to investigate cell osmotic behavior at subzero temperatures without ice formation. In the study cells were directly injected into super-cooled CPA solutions mounted on a cryomicroscope, and the corresponding osmotic properties were measured. Using ethylene glycol (EG), the value of PEG for mouse (CD-1) metaphase II oocytes at 0, -5, -10 degree C was determined to be 8.451.20, 7.430.91, 6.401.10, x10-6 cm/min, respectively, and Ea(PEG) was calculated to be 3.9 kCal/mol. Lp in the presence of EG (Lp(EG)) at 0, -5, -10 , -15 degree C was determined to be 7.0 1.15, 4.90 1.20, 2.44 0.31, 1.200.24, x 10(-2) µm/min/atm, respectively, and Ea(Lp) was calculated to be 15.5 kCal/mol. Comparing these values with those previously measured at superzero temperatures, we concluded that for mouse oocytes, the Arrhenius relationship for Lp(EG) is consistent at superzero and subzero temperatures, but the values of PEG at subzero temperatures are much lower than the extrapolated values from the Arrhenius relationship at superzero temperatures, possibly caused by membrane phase transition at low temperatures.

  2. Thermophysical effects of water driven copper nanoparticles on MHD axisymmetric permeable shrinking sheet: Dual-nature study.

    PubMed

    Ul Haq, Rizwan; Rajotia, D; Noor, N F M

    2016-03-01

    The present study is dedicated to analyze the dual-nature solutions of the axisymmetric flow of a magneto-hydrodynamics (MHD) nanofluid over a permeable shrinking sheet. In those phenomena where the fluid flow is due to the shrinking surface, some reverse behaviors of the flow arise because of vorticity effects. Despite of heat transfer analysis, the main purpose of the present study is to attain the solutions of the complex nature problem that appear in reverse flow phenomena. Thermophysical properties of both base fluid (water) and nanoparticles (copper) are also taken into account. By means of similarity transformation, partial differential equations are converted into a system of coupled nonlinear ordinary differential equations and then solved via the Runge-Kutta method. These results are divided separately into two cases: the first one is the unidirectional shrinking along the surface (m = 1) and the other one is for axisymmetric shrinking phenomena (m = 2) . To enhance the thermal conductivity of base fluid, nanoparticle volume fractions (0≤φ ≤ 0.2)) are incorporated within the base fluid. The numerical investigation explores the condition of existence, non-existence and the duality of similarity solution depends upon the range of suction parameter (S) and Hartmann number (M). The reduced skin friction coefficient and local Nusselt number are plotted to analyze the fluid flow and heat transfer at the surface of the shrinking sheet. Streamlines and isotherms are also plotted against the engineering control parameters to analyze the flow behavior and heat transfer within the whole domain. Throughout this analysis it is found that both nanoparticle volume fraction and Hartmann number are increasing functions of both skin friction coefficient and Nusselt number.

  3. Involvement of MAPK ERK activation in upregulation of water channel protein aquaporin 1 in a mouse model of Bell's palsy.

    PubMed

    Fang, Fan; Liu, Cai-Yue; Zhang, Jie; Zhu, Lie; Qian, Yu-Xin; Yi, Jing; Xiang, Zheng-Hua; Wang, Hui; Jiang, Hua

    2015-05-01

    The aim of this study is to immunolocalize the aquaporin 1 water channel protein (AQP1) in Schwann cells of idiopathic facial nerve and explore its possible role during the development of facial palsy induced by herpes simplex virus type 1 (HSV-1). HSV-1 was inoculated into the surface of posterior auricle of mouse to establish a paralyzed animal model. In HSV-1-induced facial palsy mice, protein levels of AQP1 significantly increased on the 9th to 16th day after inoculation of HSV-1. The upregulation of AQP1 was closely related to the intratemporal facial nerve edema in facial nerve canal, which was also consistent with the symptom of facial palsy in mice. In a hypoxia model of Schwann cells in vitro, we found that U0126, an ERK antagonist, inhibited not only morphological changes of cultures Schwann cells but also upregulation of both AQP1 and phosphorylated ERK. Combined with increased phosphorylated ERK in HSV-1-induced facial palsy mice, we inferred that ERK MAPK pathway might also be involved in increased AQP1 in mouse model of Bell's palsy. Although the precise mechanism needs to be further explored, our findings suggest that AQP1 in Schwann cells of intratemporal facial nerve is involved in the evolution of facial palsy induced by HSV-1 and may play an important role in the pathogenesis of this disease. AQP1 might be a potential target, and the ERK antagonist U0126 could be a new drug for the treatment of HSV-1-induced Bell's palsy in an early stage.

  4. Pharmacological blockade of aquaporin-1 water channel by AqB013 restricts migration and invasiveness of colon cancer cells and prevents endothelial tube formation in vitro.

    PubMed

    Dorward, Hilary S; Du, Alice; Bruhn, Maressa A; Wrin, Joseph; Pei, Jinxin V; Evdokiou, Andreas; Price, Timothy J; Yool, Andrea J; Hardingham, Jennifer E

    2016-02-24

    Aquaporins (AQP) are water channel proteins that enable fluid fluxes across cell membranes, important for homeostasis of the tissue environment and for cell migration. AQP1 knockout mouse models of human cancers showed marked inhibition of tumor-induced angiogenesis, and in pre-clinical studies of colon adenocarcinomas, forced over-expression of AQP1 was shown to increase angiogenesis, invasion and metastasis. We have synthesized small molecule antagonists of AQP1. Our hypothesis is that inhibition of AQP1 will reduce migration and invasiveness of colon cancer cells, and the migration and tube-forming capacity of endothelial cells in vitro. Expression of AQP1 in cell lines was assessed by quantitative (q) PCR, western blot and immunofluorescence, while expression of AQP1 in human colon tumour tissue was assessed by immunohistochemistry. The effect of varying concentrations of the AQP1 inhibitor AqB013 was tested on human colon cancer cell lines expressing high versus low levels of AQP1, using wound closure (migration) assays, matrigel invasion assays, and proliferation assays. The effect of AqB013 on angiogenesis was tested using an endothelial cell tube-formation assay. HT29 colon cancer cells with high AQP1 levels showed significant inhibition of migration compared to vehicle control of 27.9% ± 2.6% (p < 0.0001) and 41.2% ± 2.7 (p <0.0001) treated with 160 or 320 μM AqB013 respectively, whereas there was no effect on migration of HCT-116 cells with low AQP1 expression. In an invasion assay, HT29 cells treated with 160 μM of AqB013, showed a 60.3% ± 8.5% decrease in invasion at 144 hours (p < 0.0001) and significantly decreased rate of invasion compared with the vehicle control (F-test, p = 0.001). Almost complete inhibition of endothelial tube formation (angiogenesis assay) was achieved at 80 μM AqB013 compared to vehicle control (p < 0.0001). These data provide good evidence for further testing of the inhibitor as a therapeutic agent in colon cancer.

  5. Use of Pore water Rn and Ra Profiles to Evaluate the Nature of Flow through Permeable Coastal Sands in Huntington Beach, Southern California

    NASA Astrophysics Data System (ADS)

    Hammond, D. E.; Colbert, S. L.; Talsky, H.; Schwartz, R. J.

    2008-12-01

    Submarine Groundwater Discharge (SGD), as commonly defined, can represent (1) water recharged above sea level, or (2) water that is circulated locally through permeable sediments by pressure gradients generated by flow over rough topography, by wave activity, and by physical pumping of irrigating macrofauna. Under some circumstances, rapid increases in water column density over time could also drive episodes of pore fluid circulation. Budgets for radium isotopes in the water column have been used to evaluate SGD in a number of recent studies, and used to calculate fluxes of nutrients due to SGD. However, because the scale distances for nutrients may differ from those of the Ra isotopes, it is important to constrain whether SGD calculated from near-shore water column Ra budgets represents local circulation of overlying water through sediments, or regional flow driven by recharge above sea level. This also can define whether nutrient fluxes are driven by re-mineralization of biogenic material formed in the overlying water, or by transport from adjacent land areas. We have measured profiles of Rn-222 and Ra isotopes (223,224, 228) in pore waters of permeable sediments offshore from Huntington Beach on multiple occasions, working at the shoreline and at water depths of 5 to 15 m. By also determining the rate at which these isotopes emanate from solid phases and the adsorption constant for Ra on solid phases, we can evaluate the nature of SGD circulation in this system. Results indicate that nearly all of the SGD is due to local recirculation of overlying water, with macrofaunal irrigation probably driving most of the flow. Ra-228 profiles, coupled with water column budgets, can be used to put constraints on regional vertical flow.

  6. A comparison of polycyclic aromatic hydrocarbon and petroleum hydrocarbon uptake by mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) in Hong Kong coastal waters.

    PubMed

    Richardson, Bruce J; Zheng, Gene J; Tse, Edmund S C; De Luca-Abbott, Sharon B; Siu, Stanley Y M; Lam, Paul K S

    2003-01-01

    The ability of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) to accumulate polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbons (PHCs) from five sites in Hong Kong's coastal waters was compared. Mussels consistently had higher levels of contaminants, but their utility was limited at one highly polluted site due to mortality. Mussels and SPMDs ranked sites differently in terms of individual contaminant levels. Although SPMDs overcome many of the disadvantages of using living organisms to measure contaminants in marine waters, they cannot be used as "mimics" due to different PAH and PHC accumulation patterns.

  7. Investigation of self-sealing in high-strength and ultra-low-permeability concrete in water using micro-focus X-ray CT

    SciTech Connect

    Fukuda, Daisuke; Nara, Yoshitaka; Kobayashi, Yuya; Maruyama, Megumi; Koketsu, Mayuko; Hayashi, Daisuke; Ogawa, Hideo; Kaneko, Katsuhiko

    2012-11-15

    High-strength and ultra-low-permeability concrete (HSULPC) is thought to be useful as a radioactive waste package. Thus, a high confining ability is desirable. For cementitious materials, sealing of cracks may occur in water due to the precipitation of calcium compounds. This can affect the confining ability. In this study, the sealing of a crack in HSULPC in water was investigated using micro-focus X-ray computed tomography (CT). The sealing by precipitation occurred only around the end of the specimen. Sealed regions of the crack were identified using three-dimensional image registration and CT image subtraction of images obtained for the specimen before and after it was immersed in water to evaluate temporal changes of the sealing deposits in the crack. The sealing deposits increased as the HSULPC specimen was kept in water longer. It was concluded that cracks in HSULPC in water are sealed by precipitation.

  8. Expression and functional characterization of four aquaporin water channels from the European eel (Anguilla anguilla).

    PubMed

    MacIver, Bryce; Cutler, Christopher P; Yin, Jia; Hill, Myles G; Zeidel, Mark L; Hill, Warren G

    2009-09-01

    The European eel is a euryhaline teleost which has been shown to differentially up- and downregulate aquaporin (AQP) water channels in response to changes in environmental salinity. We have characterized the transport properties of four aquaporins localized to osmoregulatory organs - gill, esophagus, intestine and kidney. By sequence comparison these four AQP orthologs resemble human AQP1 (eel AQP1), AQP3 (eel AQP3) and AQP10 (AQPe). The fourth member is a duplicate form of AQP1 (AQP1dup) thought to arise from a duplication of the teleost genome. Using heterologous expression in Xenopus oocytes we demonstrate that all four eel orthologs transport water and are mercury inhibitable. Eel AQP3 and AQPe also transport urea and glycerol, making them aquaglyceroporins. Eel AQP3 is dramatically inhibited by extracellular acidity (91% and 69% inhibition of water and glycerol transport respectively at pH 6.5) consistent with channel gating by protons. Maximal water flux of eel AQP3 occurred around pH 8.2 - close to the physiological pH of plasma in the eel. Exposure of AQP-expressing oocytes to heavy metals revealed that eel AQP3 is highly sensitive to extracellular nickel and zinc (88.3% and 86.3% inhibition, respectively) but less sensitive to copper (56.4% inhibition). Surprisingly, copper had a stimulatory effect on eel AQP1 (153.7% activity of control). Copper, nickel and zinc did not affect AQP1dup or AQPe. We establish that all four eel AQP orthologs have similar transport profiles to their human counterparts, with eel AQP3 exhibiting some differences in its sensitivity to metals. This is the first investigation of the transport properties and inhibitor sensitivity of salinity-regulated aquaporins from a euryhaline species. Our results indicate a need to further investigate the deleterious effects of metal pollutants on AQP-containing epithelial cells of the gill and gastrointestinal tract at environmentally appropriate concentrations.

  9. Expression and functional characterization of four aquaporin water channels from the European eel (Anguilla anguilla)

    PubMed Central

    MacIver, Bryce; Cutler, Christopher P.; Yin, Jia; Hill, Myles G.; Zeidel, Mark L.; Hill, Warren G.

    2009-01-01

    Summary The European eel is a euryhaline teleost which has been shown to differentially up- and downregulate aquaporin (AQP) water channels in response to changes in environmental salinity. We have characterized the transport properties of four aquaporins localized to osmoregulatory organs – gill, esophagus, intestine and kidney. By sequence comparison these four AQP orthologs resemble human AQP1 (eel AQP1), AQP3 (eel AQP3) and AQP10 (AQPe). The fourth member is a duplicate form of AQP1 (AQP1dup) thought to arise from a duplication of the teleost genome. Using heterologous expression in Xenopus oocytes we demonstrate that all four eel orthologs transport water and are mercury inhibitable. Eel AQP3 and AQPe also transport urea and glycerol, making them aquaglyceroporins. Eel AQP3 is dramatically inhibited by extracellular acidity (91% and 69% inhibition of water and glycerol transport respectively at pH 6.5) consistent with channel gating by protons. Maximal water flux of eel AQP3 occurred around pH 8.2 – close to the physiological pH of plasma in the eel. Exposure of AQP-expressing oocytes to heavy metals revealed that eel AQP3 is highly sensitive to extracellular nickel and zinc (88.3% and 86.3% inhibition, respectively) but less sensitive to copper (56.4% inhibition). Surprisingly, copper had a stimulatory effect on eel AQP1 (153.7% activity of control). Copper, nickel and zinc did not affect AQP1dup or AQPe. We establish that all four eel AQP orthologs have similar transport profiles to their human counterparts, with eel AQP3 exhibiting some differences in its sensitivity to metals. This is the first investigation of the transport properties and inhibitor sensitivity of salinity-regulated aquaporins from a euryhaline species. Our results indicate a need to further investigate the deleterious effects of metal pollutants on AQP-containing epithelial cells of the gill and gastrointestinal tract at environmentally appropriate concentrations. PMID:19684221

  10. CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 2 LONG-TERM MONITORING OF PRBS: SOIL AND GROUND WATER SAMPLING

    EPA Science Inventory

    This report discusses soil and ground-water sampling methods and procedures used to evaluate the long-term performance of permeable reactive barriers (PRBS) at two sites, Elizabeth City, NC, and the Denver Federal Center near Lakewood, CO. Both PRBs were installed in 1996 and hav...

  11. CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 2 LONG-TERM MONITORING OF PRBS: SOIL AND GROUND WATER SAMPLING

    EPA Science Inventory

    This report discusses soil and ground-water sampling methods and procedures used to evaluate the long-term performance of permeable reactive barriers (PRBS) at two sites, Elizabeth City, NC, and the Denver Federal Center near Lakewood, CO. Both PRBs were installed in 1996 and hav...

  12. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

    PubMed

    Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Ectopic expression of Arabidopsis thaliana plasma membrane intrinsic protein 2 aquaporins in lily pollen increases the plasma membrane water permeability of grain but not of tube protoplasts

    PubMed Central

    Sommer, Aniela; Geist, Birgit; Da Ines, Olivier; Gehwolf, Renate; Schäffner, Anton R.; Obermeyer, Gerhard

    2010-01-01

    Summary To investigate the role of aquaporin-mediated water transport during pollen grain germination and tube growth, Arabidopsis thaliana plasma membrane intrinsic proteins (PIPs) were expressed in pollen of Lilium longiflorum (lily). Successful expression of AtPIPs in particle-bombarded lily pollen grains was monitored by co-expression with fluorescent proteins and single-cell RT-PCR, and by measuring the water permeability coefficient (Pos) in swelling assays using protoplasts prepared from transformed pollen grains and tubes. Expression of AtPIP1;1 and AtPIP1;2 in pollen grains resulted in Pos values similar to those measured in nontransformed pollen grain protoplasts (6.65 ± 2.41 μm s−1), whereas expression of AtPIP2 significantly increased Pos (AtPIP2;1, 13.79 ± 6.38; AtPIP2;2, 10.16 ± 3.30 μm s−1). Transformation with combinations of AtPIP1 and AtPIP2 did not further enhance Pos. Native pollen tube protoplasts showed higher Pos values (13.23 ± 4.14 μm s−1) than pollen grain protoplasts but expression of AtPIP2;1 (18.85 ± 7.60 μm s−1) did not significantly increase their Pos values. Expression of none of the tested PIPs had any effect on pollen tube growth rates. The ectopic expression of AtPIP2s in lily pollen increased the water permeability of the plasma membrane in pollen grains, but not in pollen tubes. The measured endogenous water permeability does not limit water uptake during tube growth, but has to be regulated to prevent tube bursting. PMID:18761636

  14. Detection of semi-volatile organic compounds in permeable pavement infiltrate

    EPA Science Inventory

    Abstract The Edison Environmental Center (EEC) has a research and demonstration permeable parking lot comprised of three different permeable systems: permeable asphalt, porous concrete and interlocking concrete permeable pavers. Water quality and quantity analysis has been ongoin...

  15. Detection of semi-volatile organic compounds in permeable pavement infiltrate

    EPA Science Inventory

    Abstract The Edison Environmental Center (EEC) has a research and demonstration permeable parking lot comprised of three different permeable systems: permeable asphalt, porous concrete and interlocking concrete permeable pavers. Water quality and quantity analysis has been ongoin...

  16. Permeability evolution of normal faults with clay smear: insights from structural observations in water saturated sandbox models and numerical simulations

    NASA Astrophysics Data System (ADS)

    Kettermann, Michael; Urai, Janos L.; Vrolijk, Peter J.

    2017-04-01

    Fault processes are complex phenomena that defy reliable prediction. Clay smear in particular is difficult to predict for sub-surface flow applications and would benefit from an improved understanding of controlling processes. In this study, we present a series of water-saturated sandbox experiments producing large clay smear surfaces up to 500 cm2. In these experiments, we couple across-fault flow measurements with structural analysis of post-mortem excavated clay smear surfaces. To develop a tool for evaluating the evolving fault structure during formation, we compare measured flow data to simplified numerical flow simulations. Results show diagnostic relationships between the observed fault structures and measured cross-fault flow. In experiments with one or two clay layers and a cumulative thickness of 10 mm and 100 mm displacement, we observe that normally consolidated clay, in a structural domain of graben faulting, initially yields in hybrid brittle/ductile failure. Characteristic for this type of failure is an early breaching of the clay layer by brittle fracturing causing increased cross-fault flow. However, the type of failure varies laterally and shear failure occurs as well. We observed that holes preferably form beneath extensional parts of the footwall cutoff. These can be identified in map-view as the fault curves towards the hanging wall. During the evolution of the fault, this is typically followed by fault back-stepping, formation of clay smears and reworking of clay fragments in the fault. These processes lead to slower increases of cross-fault flux. Holes that formed during the early breaching of the clay layer mostly remain open during the evolution of a fault, although there is some evidence for occasional resealing of holes. Fault zones are segmented by fault lenses, breached relays and clay smears in which sand and clay mix by deformation. Experiments with two clay layers show that holes rarely form at the same position on the fault planes

  17. TREATMENT OF METALS IN GROUND WATER USING AN ORGANIC-BASED SULFATE-REDUCING PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI) filings, limestone and pea gravel was evaluated at a former phosphate fertilizer manufacturing facility in Charleston, S.C. The PRB is designed to treat arsenic and heavy met...

  18. TREATMENT OF METALS IN GROUND WATER USING AN ORGANIC-BASED SULFATE-REDUCING PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI) filings, limestone and pea gravel was evaluated at a former phosphate fertilizer manufacturing facility in Charleston, S.C. The PRB is designed to treat arsenic and heavy met...

  19. Calculating the permeability coefficients of mixed matrix membranes of polydimethylsiloxane and silicalite crystals to various ethanol-water solutions using molecular simulations.

    EPA Science Inventory

    The permeability coefficients of mixed matrix membranes of polydimethylsiloxane (PDMS) and silicalite crystal are taken as the sum of the permeability coefficients of membrane components each weighted by their associated mass fraction. The permeability coefficient of a membrane c...

  20. Calculating the permeability coefficients of mixed matrix membranes of polydimethylsiloxane and silicalite crystals to various ethanol-water solutions using molecular simulations.

    EPA Science Inventory

    The permeability coefficients of mixed matrix membranes of polydimethylsiloxane (PDMS) and silicalite crystal are taken as the sum of the permeability coefficients of membrane components each weighted by their associated mass fraction. The permeability coefficient of a membrane c...

  1. Comparative NMR studies of diffusional water permeability of red blood cells from different species: XVIII platypus (Ornithorhynchus anatinus) and saltwater crocodile (Crocodylus porosus).

    PubMed

    Benga, Gheorghe; Chapman, Bogdan E; Cox, Guy C; Kuchel, Philip W

    2010-07-01

    As part of a programme of comparative measurements of Pd (diffusional water permeability) the RBCs (red blood cells) from an aquatic monotreme, platypus (Ornithorhynchus anatinus), and an aquatic reptile, saltwater crocodile (Crocodylus porosus) were studied. The mean diameter of platypus RBCs was estimated by light microscopy and found to be approximately 6.3 microm. Pd was measured by using an Mn2+-doping 1H NMR (nuclear magnetic resonance) technique. The Pd (cm/s) values were relatively low: approximately 2.1 x 10(-3) at 25 degrees C, 2.5 x 10(-3) at 30 degrees C, 3.4 x 10(-3) at 37 degrees C and 4.5 at 42 degrees C for the platypus RBCs and approximately 2.8 x 10(-3) at 25 degrees C, 3.2 x 10(-3) at 30 degrees C, 4.5 x 10(-3) at 37 degrees C and 5.7 x 10(-3) at 42 degrees C for the crocodile RBCs. In parallel with the low water permeability, the Ea,d (activation energy of water diffusion) was relatively high, approximately 35 kJ/mol. These results suggest that "conventional" WCPs (water channel proteins), or AQPs (aquaporins), are probably absent from the plasma membranes of RBCs from both the platypus and the saltwater crocodile.

  2. Relative Permeability of Fractured Rock

    SciTech Connect

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  3. Effect of bedrock permeability on subsurface stormflow and the water balance of a trenched hillslope at the Panola Mountain Research Watershed, Georgia, USA

    USGS Publications Warehouse

    Tromp-van, Meerveld; Peters, N.E.; McDonnell, Jeffery J.

    2007-01-01

    The effect of bedrock permeability on subsurface stormflow initiation and the hillslope water balance is poorly understood. Previous hillslope hydrological studies at the Panola Mountain Research Watershed (PMRW), Georgia, USA, have assumed that the bedrock underlying the trenched hillslope is effectively impermeable. This paper presents a series of sprinkling experiments where we test the bedrock impermeability hypothesis at the PMRW. Specifically, we quantify the bedrock permeability effects on hillslope subsurface stormflow generation and the hillslope water balance at the PMRW. Five sprinkling experiments were performed by applying 882-1676 mm of rainfall over a ???5.5 m ?? 12 m area on the lower hillslope during ???8 days. In addition to water input and output captured at the trench, we measured transpiration in 14 trees on the slope to close the water balance. Of the 193 mm day-1 applied during the later part of the sprinkling experiments when soil moisture changes were small, 175 mm day-1 (91%). Bedrock moisture was measured at three locations downslope of the water collection system in the trench. Bedrock moisture responded quickly to precipitation in early spring. Peak tracer breakthrough in response to natural precipitation in the bedrock downslope from the trench was delayed only 2 days relative to peak tracer arrival in subsurface stormflow at the trench. Leakage to bedrock influences subsurface stormflow at the storm time-scale and also the water balance of the hillslope. This has important implications for the age and geochemistry of the water and thus how one models this hillslope and watershed. Copyright ?? 2006 John Wiley & Sons, Ltd.

  4. Drug permeability prediction using PMF method.

    PubMed

    Meng, Fancui; Xu, Weiren

    2013-03-01

    Drug permeability determines the oral availability of drugs via cellular membranes. Poor permeability makes a drug unsuitable for further development. The permeability may be estimated as the free energy change that the drug should overcome through crossing membrane. In this paper the drug permeability was simulated using molecular dynamics method and the potential energy profile was calculated with potential of mean force (PMF) method. The membrane was simulated using DPPC bilayer and three drugs with different permeability were tested. PMF studies on these three drugs show that doxorubicin (low permeability) should pass higher free energy barrier from water to DPPC bilayer center while ibuprofen (high permeability) has a lower energy barrier. Our calculation indicates that the simulation model we built is suitable to predict drug permeability.

  5. Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from different species. V--Rabbit (Oryctolagus cuniculus).

    PubMed

    Benga, G; Matei, H; Borza, T; Poruţiu, D; Lupşe, C

    1993-10-01

    1. The diffusional water permeability (Pd) of rabbit red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS). 2. The values of Pd were around 6.3 x 10(-3) cm/sec at 15 degrees C, 7.0 x 10(-3) cm/sec at 20 degrees C, 8.0 x 10(-3) cm/sec at 25 degrees C, 9.1 x 10(-3) cm/sec at 30 degrees C and 10.7 x 10(-3) cm/sec at 37 degrees C. 3. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 15 min at 37 degrees C with 0.5 mM PCMBS. 4. The values of maximal inhibition were around 71-74% at all temperatures. 5. The basal permeability to water was estimated as 1.6 x 10(-3) cm/sec at 15 degrees C, 2.0 x 10(-3) cm/sec at 20 degrees C, 2.4 x 10(-3) cm/sec at 25 degrees C, 2.6 x 10(-3) cm/sec at 30 degrees C, and 3.1 x 10(-3) cm/sec at 37 degrees C. 6. The activation energy of water diffusion was around 18 kJ/mol and increased to 27 kcal/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion. 7. The membrane polypeptide electrophoretic pattern of rabbit RBCs has been compared with its human counterpart. 8. The rabbit membrane contained a higher amount of spectrin (bands 1 and 2), while the band 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less intense.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Dissolution and absorption modeling: model expansion to simulate the effects of precipitation, water absorption, longitudinally changing intestinal permeability, and controlled release on drug absorption.

    PubMed

    Johnson, Kevin C

    2003-09-01

    A previously described model for simulating drug dissolution, absorption, and pharmacokinetics has been expanded beyond the original application of simulating immediate-release dosage forms to include simulation of drug precipitation, water absorption from the gastrointestinal tract, changing gastrointestinal permeability, disintegration, and controlled-release and dissolution from a GITS-type dosage form. A mathematical description of the model is presented as well as a retrospective analysis of nifedipine to demonstrate the utility of the model. The fourth-order Runge-Kutta numerical method was used to solve the series of coupled differential equations used to simulate the process of dissolution, absorption, and drug disposition. The model was able to simulate the clinically demonstrated effect for drug particle size on nifedipine plasma concentrations for an immediate-release dosage form. Further simulations indicated that drug particle size was less important for a GITS-type dosage form at a release rate of 1.7 mg/hr compared to rate of 17 mg/hr. Hypothetical calculations simulated the potential effect of drug precipitation, water absorption, and changing permeability on drug plasma concentrations. The expanded model increases the utility of a previously described model in providing guidance in drug development and selection.

  7. Comparative NMR studies of diffusional water permeability of red blood cells from different species: XVI Dingo (Canis familiaris dingo) and dog (Canis familiaris).

    PubMed

    Benga, Gheorghe; Chapman, Bogdan E; Matei, Horea; Cox, Guy C; Romeo, Tony; Mironescu, Eugen; Kuchel, Philip W

    2010-03-08

    As part of a programme of comparative measurements of Pd (diffusional water permeability) the RBCs (red blood cells) from dingo (Canis familiaris dingo) and greyhound dog (Canis familiaris) were studied. The morphologies of the dingo and greyhound RBCs [examined by light and SEM (scanning electron microscopy)] were found to be very similar, with regard to aspect ratio and size; the mean diameters were estimated to be the same (approximately 7.2 microm) for both dingo and greyhound RBCs. The water diffusional permeability was monitored by using an Mn2+-doping 1H NMR technique at 400 MHz. The Pd (cm/s) values of dingo and greyhound RBCs were similar: 6.5 x 10(-3) at 25 degrees C, 7.5 x 10(-3) at 30 degrees C, 10 x 10(-3) at 37 degrees C and 11.5 x 10(-3) at 42 degrees C. The inhibitory effect of a mercury-containing SH (sulfhydryl)-modifying reagent PCMBS (p-chloromercuribenzene sulfonate) was investigated. The maximal inhibition of dingo and greyhound RBCs was reached in 15-30 min at 37 degrees C with 2 mmol/l PCMBS. The values of maximal inhibition were in the range 72-74% when measured at 25 degrees C and 30 degrees C, and approximately 66% at 37 degrees C. The lowest value of Pd (corresponding to the basal permeability to water) was approximately 2-3 x 10(-3) cm/s in the temperature range 25-37 degrees C. The Ea,d (activation energy of water diffusion) was 25 kJ/mol for dingo RBC and 23 kJ/mol for greyhound RBCs. After incubation with PCMBS, the values of Ea,d increased, reaching 46-48 kJ/mol in the condition of maximal inhibition of water exchange. The electrophoretograms of membrane polypeptides of the dingo and greyhound RBCs were compared and seen to be very similar. We postulate that the RBC parameters reported in the present study are characteristic of all canine species and, in particular in the two cases presented here, these parameters have not been changed by the peculiar Australian habitat over the millennia (as in the case of the dingo) or over

  8. Permeability evolution of shale during spontaneous imbibition

    DOE PAGES

    Chakraborty, N.; Karpyn, Z. T.; Liu, S.; ...

    2017-01-05

    Shales have small pore and throat sizes ranging from nano to micron scales, low porosity and limited permeability. The poor permeability and complex pore connectivity of shales pose technical challenges to (a) understanding flow and transport mechanisms in such systems and, (b) in predicting permeability changes under dynamic saturation conditions. This paper presents quantitative experimental evidence of the migration of water through a generic shale core plug using micro CT imaging. In addition, in-situ measurements of gas permeability were performed during counter-current spontaneous imbibition of water in nano-darcy permeability Marcellus and Haynesville core plugs. It was seen that water blocksmore » severely reduced the effective permeability of the core plugs, leading to losses of up to 99.5% of the initial permeability in experiments lasting 30 days. There was also evidence of clay swelling which further hindered gas flow. When results from this study were compared with similar counter-current gas permeability experiments reported in the literature, the initial (base) permeability of the rock was found to be a key factor in determining the time evolution of effective gas permeability during spontaneous imbibition. With time, a recovery of effective permeability was seen in the higher permeability rocks, while becoming progressively detrimental and irreversible in tighter rocks. Finally, these results suggest that matrix permeability of ultra-tight rocks is susceptible to water damage following hydraulic fracturing stimulation and, while shut-in/soaking time helps clearing-up fractures from resident fluid, its effect on the adjacent matrix permeability could be detrimental.« less

  9. Osmotic water permeability of rat intestinal brush border membrane vesicles: involvement of aquaporin-7 and aquaporin-8 and effect of metal ions.

    PubMed

    Tritto, Simona; Gastaldi, Giulia; Zelenin, Sergey; Grazioli, Monica; Orsenigo, Maria Novella; Ventura, Ulderico; Laforenza, Umberto; Zelenina, Marina

    2007-12-01

    Water channels AQP7 and AQP8 may be involved in transcellular water movement in the small intestine. We show that both AQP7 and AQP8 mRNA are expressed in rat small intestine. Immunoblot and immunohistochemistry experiments demonstrate that AQP7 and AQP8 proteins are present in the apical brush border membrane of intestinal epithelial cells. We investigated the effect of several metals and pH on the osmotic water permeability (Pf) of brush border membrane vesicles (BBMVs) and of AQP7 and AQP8 expressed in a cell line. Hg2+, Cu2+, and Zn2+ caused a significant decrease in the BBMV Pf, whereas Ni2+ and Li+ had no effect. AQP8-transfected cells showed a reduction in Pf in the presence of Hg2+ and Cu2+, whereas AQP7-transfected cells were insensitive to all tested metals. The Pf of both BBMVs and cells transfected with AQP7 and AQP8 was not affected by pH changes within the physiological range, and the Pf of BBMVs alone was not affected by phlorizin or amiloride. Our results indicate that AQP7 and AQP8 may play a role in water movement via the apical domain of small intestine epithelial cells. AQP8 may contribute to the water-imbalance-related clinical symptoms apparent after ingestion of high doses of Hg2+ and Cu2+.

  10. Mechanical properties and water vapour permeability of film from Haruan (Channa striatus) and fusidic acid spray for wound dressing and wound healing.

    PubMed

    Febriyenti; Noor, Azmin Mohd; Bai, Saringat Bin

    2010-04-01

    Aerosol is a new dosage form for wound dressing and wound healing. Concentrate of aerosols which were prepared for wound dressing and wound healing will produced films after sprayed onto the surface of wounds. The aim of this study is to evaluate the mechanical and water vapour permeability properties of the films from the aerosol concentrates. Film forming dispersions contained Haruan extract and Fusidic acid as the active ingredients, hydroxypropyl methylcellulose (HPMC) as polymer and polyethylene glycol (PEG) 400, glycerin and propylene glycol as plasticizers. Haruan extract is used to promote healing and Fusidic acid is added in formula as antibiotic to prevent the infections. The films were prepared by using casting technique. Based on the results, it is concluded that films produced from Formula E1, E2 and F4 possessed good elongation at break but low tensile strength. All Formula E, Formula F4 and F5 were permeable but Formula F5 was brittle and would peel off by themselves from the Petri dish.

  11. Aquaporin-1 Tunes Pain Perception by Interaction with Nav1.8 Na+ Channels in Dorsal Root Ganglion Neurons*

    PubMed Central

    Zhang, Hua; Verkman, A. S.

    2010-01-01

    Aquaporin-1 (AQP1) water channels are expressed in the plasma membrane of dorsal root ganglion (DRG) neurons. We found reduced osmotic water permeability in freshly isolated DRG neurons from AQP1−/− versus AQP1+/+ mice. Behavioral studies showed greatly reduced thermal inflammatory pain perception in AQP1−/− mice evoked by bradykinin, prostaglandin E2, and capsaicin as well as reduced cold pain perception. Patch clamp of freshly isolated DRG neurons showed reduced action potential firing in response to current injections. Single action potentials after pulse current injections showed reduced maximum inward current, suggesting impaired Nav1.8 Na+ function. Whole-cell Nav1.8 Na+ currents in Nav1.8-expressing ND7-23 cells showed slowed frequency-dependent inactivation after AQP1 transfection. Immunoprecipitation studies showed AQP1- Nav1.8 Na+ interaction, which was verified in live cells by single-particle tracking of quantum dot-labeled AQP1. Our results implicate the involvement of AQP1 in DRG neurons for the perception of inflammatory thermal pain and cold pain, whose molecular basis is accounted for, in part, by reduced Nav1.8-dependent membrane Na+ current. AQP1 is, thus, a novel target for pain management. PMID:20018876

  12. Evaluation of the "DSPM" model on a titania membrane: measurements of charged and uncharged solute retention, electrokinetic charge, pore size, and water permeability.

    PubMed

    Labbez, C; Fievet, P; Thomas, F; Szymczyk, A; Vidonne, A; Foissy, A; Pagetti, P

    2003-06-01

    The DSPM (Donnan steric partitioning pore model) was evaluated in the case of a titania membrane with "nanofiltration properties" by measuring the electrokinetic charge, pore size, and water permeability of the membrane, along with charged and uncharged solute retention. The zeta potential values (zeta) were determined from measurements of the electrophoretic mobility (EM) of titania powder forming the filtering layer of the membrane. Zeta potential values were converted into membrane volume charge (X) by assuming two limiting cases: a constant surface charge (sigma(s)(cst)) and a constant surface potential (psi(s)(cst)). The mean pore radius and thickness/porosity ratio of the membrane were determined by permporometry and from water permeability measurements, respectively. Retention measurements were carried out as a function of the permeate volume flux for both neutral solutes (polyethylene glycol PEG of different size) and salts (KCl, MgSO4, K2SO4, and MgCl2) at various pH values. Ionic retentions showed minimum values near the IEP of the membrane. Retention data were analyzed using the DSPM. Very good agreement was found between the pore radius calculated by the model and that determined by permporometry. X values calculated from fitting retention data using the DSPM were also in satisfactorily agreement with X values calculated from EM measurements assuming a constant surface potential for a large pH range. Furthermore, the DSPM leads to X values (X(DSPM)) between those calculated from EM (X(EM)) using the two limiting bounds. In other words, X(DSPM) was higher than X(EM) assuming psi(s)(cst) at pH values far from the isoelectric point (IEP) and lower than X(EM) assuming sigma(s)(cst). These results show that the DSPM is in qualitative agreement with the charge regulation theory (increase of the pore surface potential and decrease of the pore surface charge density with decreasing the pore size). On the other hand, the thickness/porosity ratio of the membrane

  13. Unique and analogous functions of aquaporin O for fiber cell architecture and ocular lens transparency

    SciTech Connect

    Kumari, S.S.; Eswaramoorthy, S.; Mathias, R. T.; Varadaraj, K.

    2011-09-01

    Aquaporin (AQP) 1 and AQP0 water channels are expressed in lens epithelial and fiber cells, respectively, facilitating fluid circulation for nourishing the avascular lens to maintain transparency. Even though AQP0 water permeability is 40-fold less than AQP1, AQP0 is selectively expressed in the fibers. Delimited AQP0 fiber expression is attributed to a unique structural role as an adhesion protein. To validate this notion, we determined if wild type (WT) lens ultrastructure and fibercell adhesion are different in AQP0{sup -/-}, and TgAQP1{sup +/+}/AQP0{sup -/-} mice that transgenically express AQP1 (TgAQP1) in fibercells without AQP0 (AQP0{sup -/-}). In WT, lenses were transparent with 'Y' sutures. Fibers contained opposite end curvature, lateral interdigitations, hexagonal shape, and were arranged as concentric growth shells. AQP0{sup -/-}lenses were cataractous, lacked 'Y' sutures, ordered packing and well-defined lateral interdigitations. TgAQP1{sup +/+}/AQP0{sup -/-} lenses showed improvement in transparency and lateral interdigitations in the outer cortex while inner cortex and nuclear f