To better understand radiation-matter interaction at the surface, we perform grazing incidence x-ray diffraction (GIXRD) measurements of a deuterium-ion (D-ion) plasma-irradiated bulk zinc oxide (ZnO) single crystal. The D-ion-irradiated crystal exhibits the (100) reflection of hexagonal wurtzite ZnO similar to the non-irradiated sample but with an asymmetric and shifted peak, broader rocking curve, larger a-axis lattice constant, and positive Cauchy strain along the a-axis. These structural properties are attributed to the presence of a strained lattice on the irradiated surface of the bulk crystal. D-ion irradiation of the ZnO (100) surface leads to a lattice expansion along the crystals a-axis and in-plane compression along the c-axis. Our results show the specific effects of D-ion plasma irradiation on the ZnO crystal lattice along with the interaction of D-ions with the ZnO surface.. ...
TY - JOUR. T1 - Fluorescence modulation sensing of positively and negatively charged proteins on lipid bilayers. AU - Robison, Aaron D.. AU - Huang, Da. AU - Jung, Hyunsook. AU - Cremer, Paul S.. PY - 2013/1/1. Y1 - 2013/1/1. N2 - Background: Detecting ligand-receptor binding on cell membrane surfaces is required to understand their function and behavior. Detection platforms can also provide an avenue for the development of medical devices and sensor biotechnology. The use of fluorescence techniques for such purposes is highly desirable as they provide high sensitivity. Herein, we describe a technique that utilizes the sensitivity of fluorescence without directly tagging the analyte of interest to monitor ligand-receptor interactions on supported lipid bilayers. The fluorescence signal is modulated according to the charge state of the target analyte. The binding event elicits protonation or deprotonation of pH-responsive reporter dyes embedded in the lipid bilayer. Methods: Supported lipid ...
TY - JOUR. T1 - Diffusion limitation in the block by symmetric tetraalkylammonium ions of anthrax toxin channels in planar phospholipid bilayer membranes. AU - Blaustein, Robert O.. AU - Finkelstein, Alan. PY - 1990/11. Y1 - 1990/11. N2 - Current flow through the channel formed in planar phospholipid bilayer membranes by the PA65 fragment of anthrax toxin is blocked, in a voltage-dependent manner, by tetraalkylammonium ions (at micromolar concentrations), which bind to a blocking site within the channel lumen. We have presented evidence that diffusion plays a significant role in the kinetics of blocking by tetrabutylammonium ion (Bu4N+) from the cis (toxin-containing) side of the membrane (Blaustein, R. O., E. J. A. Lea, and A. Finkelstein. 1990. J. Gen. Physiol. 96:921-942); in this paper we examine the implications and consequences of diffusion control for binding kinetics. As expected for a diffusion-affected reaction, both the entry rate constant (k1cis) of Bu4N+ from the cis solution to the ...
... , Authors: Atsuhiro Tanabe, Maho Saito. Published in: Atlas Genet Cytogenet Oncol Haematol.
The present invention generally relates to the field of pharmaceutical sciences. More specifically, the present invention includes apparatus and devices for the preparation of pharmaceutical formulations containing large diameter synthetic membrane vesicles, such as multivesicular liposomes, methods for preparing such formulations, and the use of specific formulations for therapeutic treatment of subjects in need thereof. Formation and use of the pharmaceutical formulations containing large diameter synthetic membrane vesicles produced by using the apparatus and devices for therapeutic treatment of subjects in need thereof is also contemplated.
Looking for online definition of Plasma membrane calcium pump isoform 4 in the Medical Dictionary? Plasma membrane calcium pump isoform 4 explanation free. What is Plasma membrane calcium pump isoform 4? Meaning of Plasma membrane calcium pump isoform 4 medical term. What does Plasma membrane calcium pump isoform 4 mean?
TY - JOUR. T1 - Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells. AU - Yang,Jingshuai. AU - Li,Qingfeng. AU - Jensen,Jens Oluf. AU - Pan,Chao. AU - Cleemann,Lars Nilausen. AU - Bjerrum,Niels J.. AU - He,Ronghuan. PY - 2012. Y1 - 2012. N2 - A novel acid-base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.e. methyl (MePSU), ethyl (EtPSU) and butyl (BuPSU) imidazoliums, as revealed by 1H NMR spectra. The imidazolium polysulfone membranes are then doped with phosphoric acid and used as a proton exchange membrane electrolyte in fuel cells. An acid doping level of about 10-11mol H3PO4 per mole of the imidazolium group is achieved in 85wt% H3PO4 at room temperature. The membranes exhibit a proton conductivity of ...
Background: Although suicide is a leading cause of death in the United States and represents a significant public health threat, little is known about the neurobiological or molecular factors that contribute to its pathophysiology. A number of studies now indicate that lithium has considerable efficacy in the prevention of suicide in patients with affective disorders, and accumulating evidence indicates that protein kinase C (PKC) and its substrates, in particular the myristoylated alanine-rich C kinase substrate (MARCKS), are primary targets of chronic lithium treatment. We therefore hypothesized that a dysregulation in MARCKS expression in key brain regions could contribute to the pathophysiology associated with suicide. To address this, we examined MARCKS, as well as the closely related MARCKS-related protein (MRP), mRNA expression in the hippocampus and dorsolateral prefrontal cortex of suicide victims and normal controls. Method: MARCKS and MRP mRNA expression was assessed by quantitative ...
Looking for online definition of fetal membrane retention in the Medical Dictionary? fetal membrane retention explanation free. What is fetal membrane retention? Meaning of fetal membrane retention medical term. What does fetal membrane retention mean?
Looking for online definition of cystic fibrosis transmembrane conductance regulator gene in the Medical Dictionary? cystic fibrosis transmembrane conductance regulator gene explanation free. What is cystic fibrosis transmembrane conductance regulator gene? Meaning of cystic fibrosis transmembrane conductance regulator gene medical term. What does cystic fibrosis transmembrane conductance regulator gene mean?
Publisher: University of Delaware. Date Issued: 2015. Abstract: Structural mechanisms and underlying thermodynamic determinants of efficient internalization of charged cationic peptides (cell-penetrating peptides, CPPs) such as TAT, polyarginine, and their variants, into cells, cellular constructs, and model membrane/lipid bilayers (large and giant unilamellar or multilamelar vesicles) continue to garner significant attention. Two widely-held views on the translocation mechanism center on endocytotic and non-endocytotic (diffusive) processes. Using the translocation of short, charged cationic oligo-arginine peptides (mono-, di-, and tri-arginine) from bulk aqueous solution into model DMPC bilayers, we explore the question of the similarity of thermodynamic and structural predictions obtained from molecular dynamics simulations using all-atom and the Martini coarse-grain force fields. Specifically, we estimate potentials of mean force associated with translocation using standard all-atom ...
TY - JOUR. T1 - Methanol crossover through PtRu/Nafion composite membrane for a direct methanol fuel cell. AU - Jung, E. H.. AU - Jung, U. H.. AU - Yang, T. H.. AU - Peak, D. H.. AU - Jung, D. H.. AU - Kim, Sung Hyun. PY - 2007/5/1. Y1 - 2007/5/1. N2 - This study examined methanol crossover through PtRu/Nafion composite membranes for the direct methanol fuel cell. For this purpose, 0.03, 0.05 and 0.10 wt% PtRu/Nafion composite membranes were fabricated using a solution impregnation method. The composite membrane was characterized by inductively coupled plasma-mass spectroscopy and thermo-gravimetric analysis. The methanol permeability and proton conductivity of the composite membranes were measured by gas chromatography and impedance spectroscopy, respectively. In addition, the composite membrane performance was evaluated using a single cell test. The proton conductivity of the composite membrane decreased with increasing number of PtRu particles embedded in the pure Nafion membrane, while the ...
Polyvinylidene fluoride (PVDF) hollow fibre membranes with asymmetric structures and good hydrophobicity have been prepared by a phase-inversion method and have been applied to removal of ammonia from water. Aqueous solution containing sulfuric acid was used as stripping solution to accelerate the removal of ammonia. A mathematical model was presented to simulate the ammonia removal in PVDF hollow fibre modules. Experimental results indicate that the post-treatment with ethanol is useful to improve both the hydrophobility and the effective surface porosity of the resulting PVDF hollow fibre membranes, and thus favors the ammonia removal. Increasing the pH value of water is capable of promoting the removal of ammonia. The initial concentration of ammonia and the feed velocity of the acid stripping solution have negligible effects on the ammonia removal. The ammonia stripping rate increases as the feed velocity is increased up to 0.59 m/s or Re > 0.32, after which the feed velocity shows no ...
TY - JOUR. T1 - Characterization of apical and basolateral plasma membrane domains derived from cultured rat cholangiocytes. AU - Tietz, Pamela. AU - Levine, Susan. AU - Holman, Ralph. AU - Fretham, Chris. AU - La Russo, Nicholas F. PY - 1997/12/15. Y1 - 1997/12/15. N2 - Cholangiocytes, the epithelial cells that line intrahepatic bile ducts, are composed of plasma membranes with discrete apical (lumenal) and basolateral domains that contain different channels, transporters, and receptors. In recent work, we developed a long-term, primary culture system of normal rat cholangiocytes (NRC). Our aims here were to prepare and characterize apical and basolateral plasma membrane vesicles from NRC. Using serial isopycnic centrifugation on sucrose gradients, we generated separate apical and basolateral plasma membrane vesicles. We characterized these vesicles by transmission electron microscopy, specific marker enzyme assays, and immunoblotting; we also determined the percentage of sealed vesicles and ...
Cholesterol- and glycosphingolipid-enriched membrane lipid microdomains, frequently called lipid rafts, are thought to play an important role in the spatial and temporal organization of immunological synapses. Higher ordering of lipid acyl chains was suggested for these entities and imaging of membrane order in living cells during activation can therefore help to understand the mechanisms responsible for the supramolecular organization of molecules involved in the activation of T cells. Here, we employ the phase-sensitive membrane dye di-4-ANEPPDHQ together with a variety of spectrally-resolved microscopy techniques, including 2-channel ratiometric TIRF microscopy and fluorescence lifetime imaging, to characterize membrane order at the T cell immunological synapse at high spatial and temporal resolution in live cells at physiological temperature. We find that higher membrane order resides at the immunological synapse periphery where proximal signalling through the immunoreceptors and accessory proteins
The surface-accessible ectodomain region of the Plasmodium falciparum apical membrane antigen 1 (AMA1) is a malaria vaccine candidate. The amino acid sequence may be under selection from naturally acquired immune responses, and previous analyses with a small number of allele sequences indicate a non-neutral pattern of nucleotide variation. To investigate whether there is selection to maintain polymorphism within a population, and to identify the parts of the ectodomain under strongest selection, a sample of 51 alleles from a single endemic population was studied. Analyses using Fu and Lis D and F tests, Tajimas D test, and the McDonald-Kreitman test (with the chimpanzee parasite P. reichenowi as outgroup) show significant departure from neutrality and indicate the selective maintenance of alleles within the population. There is also evidence of a very high recombination rate throughout the sequence, as estimated by the recombination parameter, C, and by the rapid decline in linkage disequilibrium with
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Looking for online definition of peroxisomal membrane protein 2 in the Medical Dictionary? peroxisomal membrane protein 2 explanation free. What is peroxisomal membrane protein 2? Meaning of peroxisomal membrane protein 2 medical term. What does peroxisomal membrane protein 2 mean?
Gloeobacter violaceus sp. PCC 7421 is an unusual cyanobacterium with only one cellular membrane, which lacks the thylakoid membranes found in other oxygenic photosynthetic organisms. The cell membrane lipids in G. violaceus sp. PCC 7421 are monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidyl glycerol and phosphatidic acid in the molar proportion of 51, 24, 18 and 4% respectively. This lipid composition resembles that of the cell membrane from other cyanobacteria, but completely lacks sulfoquinovosyl diacylglycerol. This lack of sulfoquinovosyl diacylglycerol is exceptional for a photosynthetic membrane. The membrane lipids are esterified to 14:0, 16:0, 16:1, 18:0, 18:1, 18:2 and alpha 18:3 fatty acids.. ...
Sterol is a major component of cell membranes in living cells. A characteristic sterol is cholesterol in animal cell membranes, stigmasterol in plants, and ergosterol in fungi. The maximum solubility of sterol in a lipid bilayer is the highest mole fraction of sterol that can be incorporated into a lipid bilayer before sterol crystals precipitate. We have investigated how the maximum solubility of cholesterol depends on the sizes of lipid head groups in POPC/POPE/cholesterol lipid bilayers and on the charges of head groups in POPS/cholesterol and POPG/cholesterol lipid bilayers. We found that the maximum solubility of cholesterol increases linearly as a function of the ratio POPC/(POPE+POPC). Our fluorescence microscopy measurements reveal phase separations and large domain formation in the mixture of POPC/POPE lipid bilayers with high amount of cholesterol. We measured maximum solubility limits of ergosterol and stigmasterol molecules in PC lipid bilayers. Our results show that minor ...
Lipid rafts are cholesterol- and glycosphingolipids- enriched microdomains on plasma membrane surface of mammal cells, involved in a variety of cellular processes. Depleting cholesterol from the plasma membrane by drugs influences the trafficking of lipid raft markers. Optical imaging techniques are powerful tools to study lipid rafts in live cells due to its noninvasive feature. In this study, breast cancer cells MCF-7 were treated with different concentrations of MβCD to deplete cholesterol and an environmentally sensitive fluorescence probe, Laurdan was loaded to image lipid order by two-photon microscopy. The generalized polarization (GP) values were calculated to distinguish the lipid order and disorder phase. GP images and GP distributions of native and cholesterol-depleted MCF-7 cells were obtained. Our results suggest that even at low concentration (0.5 mM) of MβCD, the morphology of the MCF-7 cells changes. Small high GP areas (lipid order phase) decrease more rapidly than low GP ...
Instant membrane resealing importantly contributes to the functional and structural integrity of the endothelial cells (ECs) that are exposed to various physical and chemical stimuli in blood stream. The present study was designed to explore the molecular mechanisms mediating this endothelial membrane resealing with a focus on the role of lipid rafts (LR) clustering. Using high energy Laser gun, a tiny hole was made in cultured EC bathed with FM1-43, and the rapid entry of this FM1-43 to produce fluorescence was used to measure membrane resealing. We demonstrated that ECs exhibited a Ca2+-dependent instant membrane resealing, as shown by a significant reduction of fluorescence appearance within these cells compared to ECs bathed with Ca2+ free solution. This Ca2+-dependent instant membrane resealing was also observed in ECs up stimulation of Lactobacillus casei cell wall fragments (LCWE), which was commonly used to produce arteritis. When ECs were pretreated with LRs clustering stimulators such ...
0064]The inlet end 22 of inner tube 14 has a closure shown generally at 26, including a porous membrane 28 coated with a catalyst layer 30. The details of the preferred porous membrane and catalyst are described above and not repeated here. Preferably when chemical vapor deposition is used with this apparatus 10, the catalyst layer 30 is coated on the membrane 28. The porous membrane 28 is preferably held to the inlet end 22 through the pressure differential created by the vacuum. The porous membrane 28 may also be attached or bonded to the inlet end 22 by other conventional attachment method, provided the bonding material does not chemically react with the carbon-containing gas composition or the catalyst, and provided the bond can withstand the process conditions, such as the temperatures and pressure differential. The porous membrane 28 as shown may have the shape of a flat disc and can be used in varying thicknesses. Membrane 28 has two opposing sides 32, 34. Side 32 faces in the direction ...
This study has revealed that the integral inner nuclear membrane protein Src1 functions in gene regulation of subtelomeric genes and is embedded functionally in a network of factors, which participate in transcription-coupled mRNA export. Importantly, Src1 is associated with subtelomeric chromatin and thus can help to organize this region of the chromosomes. In previous studies, Src1 was shown to contain an intron with the possibility of alternative splicing (Davis et al., 2000; Rodríguez-Navarro et al., 2002). Our study revealed that both splice forms localize to the nuclear periphery and are integral inner nuclear membrane proteins (King et al., 2006). However, both proteins are not functionally equivalent. To the best of our knowledge, this is the first demonstration that two forms of a protein generated by alternative splicing in yeast have different functions.. The N domain of Src1 mediates nuclear targeting, and insertion into the nuclear membrane requires the first transmembrane span. ...
This invention describes a new concept of flexible template-directed microporous partially pyrolyzed polymeric membranes which have greatly improved performance in separation of gas pairs compared to their precursor polymeric membranes. Organic hosts, such as crown ethers, cyclodextrins (CDs), calixarenes (CXs), and spherands, or polymeric additives, such as poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) were used as the micropore-forming templates. Micropore-forming template/polymer blend membranes comprising organic micropore-forming templates embedded in a polymer matrix were prepared by dissolving the organic micropore-forming templates in the polymer solution followed by solution-casting and solvent evaporation or solvent exchange. Low-temperature selectively pyrolyzing micropore-forming templates in the micropore-forming template/polymer blend membranes at a nitrogen flow resulted in the formation of flexible microporous partially pyrolyzed polymeric membranes.
Phospholipid molecular species and headgroup compositions were determined for sarcoplasmic reticular and microsomal membranes in two species of Sonoran desert cyprinid fish (Agosia chrysogaster Girard and Notropis lutrensis Girard) trapped in an isolated pool of a desert stream. Fish populations were sampled in the cool of the morning (water temperature 21-21.9°C for Agosia and 22-26°C for Notropis) and 7-11 h later in the heat of the afternoon (water temperature 34.2°C) to determine whether membrane lipid composition varied with sampling time and thermal exposure. The composition of sarcoplasmic reticular membranes did not vary significantly through the day. In contrast, the molecular species composition of muscle microsomes (a mixture of endoplasmic reticulum and plasma membranes) changed markedly from the cool of the morning to the heat of the afternoon in both species. Adjustments were particularly striking in phosphatidylcholine (PC). For example, in Agosia, the ratio of ...
TY - JOUR. T1 - A membrane inlet mass spectrometry system for noble gases at natural abundances in gas and water samples. AU - Visser, Ate. AU - Singleton, Michael J.. AU - Hillegonds, Darren J.. AU - Velsko, Carol A.. AU - Moran, Jean E.. AU - Esser, Bradley K.. PY - 2013/11/15. Y1 - 2013/11/15. N2 - Rationale Noble gases dissolved in groundwater can reveal paleotemperatures, recharge conditions, and precise travel times. The collection and analysis of noble gas samples are cumbersome, involving noble gas purification, cryogenic separation and static mass spectrometry. A quicker and more efficient sample analysis method is required for introduced tracer studies and laboratory experiments. Methods A Noble Gas Membrane Inlet Mass Spectrometry (NG-MIMS) system was developed to measure noble gases at natural abundances in gas and water samples. The NG-MIMS system consists of a membrane inlet, a dry-ice water trap, a carbon-dioxide trap, two getters, a gate valve, a turbomolecular pump and a ...
Abstract: Using a model of hemorrhagic shock, the possibility of protection byCu,Zn-superoxide dismutase (SOD) of the phospholipid bilayer of plasma membranes ofhepatocytes and adipocytes as well as of the blood lipoproteins was studied. SOD (5mg/kg), injected 30 min after the onset of bleeding, efficiently prevented changes in thephospholipid bilayer of hepatocytic plasma membranes in cats. Simultaneous injection ofSOD partly restored the concentration of different classes of phospholipids in plasmamembranes of mesenterial fatty tissue adipocytes altered by shock. When incorporated intoliposomes, SOD exerted a weaker corrective effect on the phospholipid composition ofhepatocytic plasma membranes in animals with hemorrhagic shock and simultaneously produceda membrane-stabilizing effect on adipocytes. In contrast to pure SOD (which had no effecton the lipoprotein composition of the blood in animals with hemorrhagic shock),SOD-containing liposomes decreased the amount of chylomicrons and very low ...
TY - JOUR. T1 - Differential roles of ionic, aliphatic, and aromatic residues in membrane - Protein interactions. T2 - A surface plasmon resonance study on phospholipases A2. AU - Stahelin, R. V.. AU - Cho, W.. PY - 2001/4/17. Y1 - 2001/4/17. N2 - The roles of cationic, aliphatic, and aromatic residues in the membrane association and dissociation of five phospholipases A2 (PLA2), including Asp-49 PLA2 from the venom of Agkistodon piscivorus piscivorus, acidic PLA2 from the venom of Naja naja atra, human group IIa and V PLA2s, and the C2 domain of cytosolic PLA2, were determined by surface plasmon resonance analysis. Cationic interfacial binding residues of A. p. piscivorus PLA2 (Lys-10) and human group IIa PLA2 (Arg-7, Lys-10, and Lys-16), which mediate electrostatic interactions with anionic membranes, primarily accelerate the membrane association. In contrast, an aliphatic side chain of the C2 domain of cytosolic PLA2 (Val-97), which penetrates into the hydrophobic core of the membrane and ...
Polyunsaturated fatty acids (PUFA) have strong effects on hibernation and daily torpor. Increased dietary uptake of PUFA of the n-6 class, particularly of Linoleic acid (LA, C18:2 n-6) lengthens torpor bout duration and enables animals to reach lower body temperatures (Tb) and metabolic rates. As previously hypothesized, this well-known influence of PUFA may be mediated via effects of the membrane fatty acid composition on sarcoplasmic reticulum (SR) Ca2+−ATPase 2a (SERCA) in the heart of hibernators. We tested the hypotheses that high proportions of n-6 PUFA in general, or specifically high proportions of LA (C18:2 n-6) in SR phospholipids (PL) should be associated with increased cardiac SERCA activity, and should allow animals to reach lower minimum Tb in torpor. We measured activity of SERCA from hearts of hibernating and non-hibernating Syrian hamsters (Mesocricetus auratus) in vitro at 35°C. Further, we determined the PL fatty acid composition of the SR membrane of these hearts. We found that
Corynebacterium jeikeium, a resident of human skin, is often associated with multidrug resistant nosocomial infections in immunodepressed patients. C. jeikeium K411 belongs to mycolic acid-containing actinomycetes, the mycolata and contains a channel-forming protein as judged from reconstitution experiments with artificial lipid bilayer experiments. The channel-forming protein was present in detergent treated cell walls and in extracts of whole cells using organic solvents. A gene coding for a 40 amino acid long polypeptide possibly responsible for the pore-forming activity was identified in the known genome of C. jeikeium by its similar chromosomal localization to known porH and porA genes of other Corynebacterium strains. The gene jk0268 was expressed in a porin deficient Corynebacterium glutamicum strain. For purification temporarily histidine-tailed or with a GST-tag at the N-terminus, the homogeneous protein caused channel-forming activity with an average conductance of 1.25 nS in 1M KCl ...
Paramecium, a unicellular ciliate, can be attracted by various chemical stimuli. Chemoattractants such as glutamate, folate, cAMP, and acetate activate different receptor mediated signal transduction pathways. The final event in these signal transductions is a hyperpolarization of membrane potential, which makes Paramecium swim smoothly and fast. There is evidence that the effecter of this hyperpolarization is the plasma membrane calcium ATPase (PMCA), that when activated, expels Ca2+ from the cell. In Paramecium three PMCA isoforms, named PMCA2, 3, and 4, have been cloned. PMCA2 is associated with lipid rafts, which is demonstrated by its resistance to cold detergent solubilization and distribution in sucrose density gradients in ultracentrifugation. PMCA3 and 4 are not associated with lipid rafts. On the cell surface, PMCAs are localized to the bases of cilia. Sterol-depletion by methyl-ß-cyclodextrin (MßCD) treatment disrupts the distribution of PMCA2 in sucrose density gradients and ciliary base
Biological light-driven proton pumps use light to move protons across a cell membrane, creating a proton gradient. Although photochromic compounds such as spiropyrans can reversibly convert between two structures with differing pKa values, spiropyrans have not been used to generate either a light-driven proton pump or an electrical current. Here, we report an artificial light-harvesting system based on a supported liquid membrane doped with a spiropyran. Irradiating the membrane with ultraviolet light induces a ring-opening reaction, converting spiropyran to merocyanine, whereas irradiation with visible light induces the reverse reaction. When the membrane is irradiated with ultraviolet and visible light on opposite sides, H+ is taken up by merocyanine, carried through the polymeric membrane and released on the other side. We show that this system produces a light-induced proton flux, an electrical current with an efficiency of ~0.12%, an open-circuit voltage of ~210 mV and a membrane gradient of ~3.6
Imaging single-channel Ca21 signals by total internal reflection fluorescence microscopy. (A) Schematic of the TIRFM imaging system. The 488-nm beam from an argon ion laser (50 mW) passes through a 53 beam expander (BE) and is focused by a lens (FL; f ¼ 150 mm) via a dichroic mirror (DM)to a spot at the back focal plane of the microscope objective lens (Olympus TIRFM 603, oil immersion, NA ¼ 1.45). The focusing lens is mounted on a micrometer-driven translation stage, so that the laser beam can be adjusted to enter the periphery of the objective aperture so as to achieve total internal reflection at the interface between the cover glass and the aqueous bathing medium. An adjustable rectangular knife-blade aperture (A) located at a conjugate image plane defines the field of excitation. Fluorescence excited in the specimen by the evanescent wave is collected by the same objective, passes through the dichroic mirror and a barrier filter (BF) blocking the laser wavelength, and is imaged by an ...
Abbreviations: CAPS, calcyphosine; CISK, cytokine-independent survival kinase; DAG, diacylglycerol; DCV, dense core vesicle; DGK, DAG kinase; EEA1, early endosomal antigen 1; ENTH, epsin N-terminal homology; ER, endoplasmic reticulum; IP3, myo-inositol 1,4,5-trisphosphate; LUV, large unilamellar vesicle; NSF, N-ethylmaleimide-sensitive factor; PH domain, pleckstrin homology domain; PI3K, phosphoinositide 3-kinase; PIP, phosphoinositide phosphate; PIP5K, PtdIns4P 5-kinase; PKC, protein kinase C; PLA, phospholipase A; PLC, phospholipase C; PLD, phospholipase D; PI-PLC, phosphoinositide-specific PLC; PtdOH, phosphatidic acid; PX domain, Phox homology domain; SARA, Smad anchor for receptor activation; SNAP, soluble NSF-attachment protein; SNARE, SNAP receptor; SCAMP2, secretory carrier membrane protein 2; VAMP, vesicle-associated membrane protein ...
This study aimed to investigate effects of citrus flavanones naringenin (NAR) and hesperetin (HES) on liver antioxidant status and membrane phospholipid composition in 24-month-old rats. NAR and HES (15 mg/kg) were administrated orally to male Wistar rats, once per day, for 4 weeks. Control group received either vehicle (sunflower oil) or remained intact. The results showed decreased (p , 0.05) activity of antioxidant enzymes (AOE), specifically catalase (CAT), superoxide dismutase (SOD) 1 and glutathione reductase (GR) in the liver of intact control old-aged rats in comparison to young intact controls. Flavanone administration to old-aged males increased (p , 0.05) examined AOE activities in comparison to vehicle-administered animals. Namely, NAR was more potent in comparison to HES regarding the increase (p , 0.05) in activities of examined antioxidant enzymes (SOD 1 and 2, glutathione peroxidase-GPx and GR) and the liver glutathione (GSH), while HES elevated (p , 0.05) only activity of CAT ...
Monoclonal antibodies were used as cytochemical markers to study surface interactions between endosymbiotic Rhizobium bacteroids from pea root nodules and the encircling peribacteroid membranes, which are of plant origin. Monoclonal antibodies that react with Rhizobium lipopolysaccharide (LPS) or with a plant membrane glycoprotein were used as markers for material from the bacteroid outer membrane or the peribacteroid membrane, respectively. Membrane-enclosed bacteroids were isolated from nodule homogenates by sucrose gradient centrifugation, and the encircling peribacteroid membrane was released by mild osmotic shock treatment. Using an immunochemical technique (sandwich ELISA), it was shown that 1-5% of the LPS antigen released into the peribacteroid fraction by mild osmotic shock treatment was physically associated with peribacteroid membrane through a detergent-sensitive linkage. This association could be visualized when freshly prepared peribacteroid material was immobilized on gold grids ...
TY - JOUR. T1 - Intracellular proton conductance of the hepatitis C virus p7 protein and its contribution to infectious virus production. AU - Wozniak, Ann L.. AU - Griffin, Stephen. AU - Rowlands, David. AU - Harris, Mark. AU - Yi, Min Kyung. AU - Lemon, Stanley M.. AU - Weinman, Steven A.. PY - 2010/9/1. Y1 - 2010/9/1. N2 - The hepatitis C virus (HCV) p7 protein is critical for virus production and an attractive antiviral target. p7 is an ion channel when reconstituted in artificial lipid bilayers, but channel function has not been demonstrated in vivo and it is unknown whether p7 channel activity plays a critical role in virus production. To evaluate the contribution of p7 to organelle pH regulation and virus production, we incorporated a fluorescent pH sensor within native, intracellular vesicles in the presence or absence of p7 expression. p7 increased proton (H+) conductance in vesicles and was able to rapidly equilibrate H+ gradients. This conductance was blocked by the viroporin ...
Ever since the emergence of the hypothesis that linked the aetiology of schizophrenia with abnormal membrane phospholipids composition, an increasing number of evidences have suggested reduced membrane polyunsaturated fatty acids in patients with schizophrenia. This has led to a conduct of several studies to evaluate the efficacy of omega-3 fatty acid supplement in the modification of membrane phospholipids and treatment of schizophrenia. The two main omega-3 fatty acid classes, EPA and DHA, play a vital role in membranes. This project work reviews omega-3 fatty acid studies and summarizes their outcomes. Eight original articles (nine studies) were reviewed. Six out of nine studies measured RBC membrane fatty acids levels and all six studies reported a significant increase in EPA after EPA supplement. Two studies reported increased DHA post omega-3 fatty acid and DHA supplement, respectively. One study observed a dose-dependent increment in DHA after EPA supplement. Improved symptoms were ...
As mentioned in our introduction, the availability of CPE-directed therapeutics could be helpful for ameliorating several CPE-associated medical conditions. A previous study had suggested that the drug mepacrine might be a candidate CPE therapeutic because the presence of this drug interferes with CPE-induced electrophysiologic activity in artificial lipid bilayers (24). However, that study did not distinguish whether mepacrine inactivates the CPE protein or instead interferes with some step in CPE action, i.e., whether this drug affects CPE binding, CPE pore formation, or CPE pore activity. Furthermore, it was specifically important to determine whether mepacrine is not only protective against CPE electrophysiologic activity in artificial membranes but also inhibits CPE-induced cytotoxicity in mammalian cells, where receptors are present and complex phenomena like membrane vesicle release occur (30).. Therefore, a first major contribution of the current study entailed demonstrating that ...
TY - JOUR. T1 - Partitioning of proteins into plasma membrane microdomains. Clustering of mutant influenza virus hemagglutinins into coated pits depends on the strength of the internalization signal. AU - Fire, Ella. AU - Brown, Claire M.. AU - Roth, Michael G.. AU - Henis, Yoav I.. AU - Petersen, Nils O.. PY - 1997/11/21. Y1 - 1997/11/21. N2 - Internalization of membrane proteins involves their recruitment into plasma membrane clathrin-coated pits, with which they are thought to interact by binding to AP-2 adaptor protein complexes. To investigate the interactions of membrane proteins with coated pits at the cell surface, we applied image correlation spectroscopy to measure directly and quantitatively the clustering of influenza hemagglutinin (HA) protein mutants carrying specific cytoplasmic internalization signals. The HA system enables direct comparison between isolated internalization signals, because HA itself is excluded from coated pits. The studies presented here provide, for the first ...
We report the use of a high-refractive-index aplanatic solid immersion lens (ASIL) in total internal reflection fluorescence (TIRF) microscopy. This new solid immersion total internal reflection fluorescence (SITIRF) microscopy allows highly confined surface imaging with a significantly reduced imaging depth compared with conventional TIRF microscopy. We explore the application of a high refractive index, low optical dispersion material zirconium dioxide in the SITIRF microscope and also introduce a novel system design which enables the SITIRF microscope to work either in the epi-fluorescence or TIRF modes with variable illumination angles. We use both synthetic and biological samples to demonstrate that the imaging depth in the SITIRF microscope can be confined to a few tens of nanometers. SITIRF microscopy has the advantages of performing highly selective imaging and high-resolution high-contrast imaging. Potential applications in biological imaging and future developments of SITIRF microscopy ...
Tight junctions between epithelial and endothelial cells form selective barriers and paracellular channels and regulate paracellular transport of solutes, immune cells, and drugs. More specifically, tight junctions consist of proteins that laterally interconnect neighboring cells of epithelia and endothelia. Certain proteins seal the tight junction, so that a nearly impermeable barrier develops, whereas others form channels that allow for permeation between the cells. Recent investigations have focused on tight junction proteins, belonging to the claudin family (claudins-1 to -27 in humans) and the newly defined group of TAMP (three proteins: occludin, Marvel-D2, and tricellulin). Barriers and Channels Formed by Tight Junction Proteins I showcases work in this area clustered around three major themes: the molecular properties of tight junctions, for example, the role of the claudin family of proteins and the formation of ion and charge-selective channels; the regulation of tight junction
Edentulism refers to a state of full or partial lack of teeth. This situation may interfere with essential functions such as mastication, speech and even appearance.. Dental implants inserted to the mandible or maxilla is a common treatment modality aiming to restore edentulus alveolar ridges by providing support and anchorage for removable or fixed dental prosthesis.There are cases which in addition to a lack of teeth suffer from lack of sufficient bone tissue volume to support the dental implant.A situation like this may originate from a variety of reasons such as residual bone atrophy, prior alveolar bone destruction due to periodontal disease and even a traumatic tooth extraction. In such cases, a routine alveolar bone augmentation is done to enable a dental implant installation at this site.Guided bone regeneration (GBR) is a widely used technique used to augment edentulus bone ridges. It relies on an inert membrane covering a bone substitute placed over the bony site requiring ...
TY - JOUR. T1 - Membrane specializations of dentritic spines and glia in the weaver mouse cerebellum. T2 - A freeze-fracture study. AU - Hanna, Robert B.. AU - Hirano, Asao. AU - Pappas, George D.. PY - 1976/3/1. Y1 - 1976/3/1. N2 - Electron microscopy of thin-sectioned and freeze-fractured preparations of the cerebellum of the weaver mouse indicates that the dendritic spines are morphologically identical to those of their normal littermates. The weaver dendritic spines have been characterized as "unattached" since the synaptic input from the parallel fibers is absent (8-10). The entire region around the dendritic spines is taken up by astrocytic processes in the weaver. The outer fracture face of a normal dendritic spine contains aggregations of 10-nm wide particles in the immediate postsynaptic region. Similar particle aggregations occur in the unattached spines of the weaver. Freeze-fracture preparations reveal rectilinear arrays of particles, having a 7-nm center-to-center distance in the ...
Exp Gerontol. 2007 Nov;42(11):1053-62. Comparative Study; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Govt
As essential media currently used in several technological applications, the accurate molecular level description of ionic liquids (ILs) at the gas-liquid interface is of utmost importance. The inherently surface-sensitive technique, sum frequency generation (SFG) spectroscopy, in combination with bulk-sensitive vibrational spectroscopic techniques such as FTIR and Raman, have been used in this report to characterize the surface of cyano-containing ILs, such as [BMIM][SCN], [BMIM][DCA], [BMIM][TCM], and [EMIM][TCB] at the gas-liquid interface. By structural variation of the anion while keeping the cation constant, emphasis on the molecular arrangement of the anion at the gas-liquid interface was reported. Vibrational modes seen in the C-H stretching region revealed the presence of the cation with an orientation independent of the type of anion. A similar arrangement at the surface as reported in previous studies was found. All three anions of varying symmetry, namely, [DCA]- (C2v), [TCM]-(D3h), ...
TY - JOUR. T1 - Suppression of Rft1 expression does not impair the transbilayer movement of Man5GlcNAc2-P-P-dolichol in sealed microsomes from yeast. AU - Rush, Jeffrey S.. AU - Gao, Ningguo. AU - Lehrman, Mark A.. AU - Matveev, Sergey. AU - Waechter, Charles J.. PY - 2009/7/24. Y1 - 2009/7/24. N2 - To further evaluate the role of Rft1 in the transbilayer movement of Man5GlcNAc2-P-P-dolichol (M5-DLO), a series of experiments was conducted with intact cells and sealed microsomal vesicles. First, an unexpectedly large accumulation (37-fold) of M5-DLO was observed in Rft1-depleted cells (YG1137) relative to Glc3Man9GlcNAc2-P-P-Dol in wild type (SS328) cells when glycolipid levels were compared by fluorophore-assisted carbohydrate electrophoresis analysis. When sealed microsomes from wild type cells and cells depleted of Rft1 were incubated with GDP-[3H]mannose or UDP-[3H]GlcNAc in the presence of unlabeled GDP-Man, no difference was observed in the rate of synthesis of [3H]Man9GlcNAc2-P-P-dolichol ...
Membrane environment and fluidity can modulate the dynamics and interactions of membrane proteins and can thereby strongly influence the function of cells and organisms in general. In this work, we demonstrate that trans-cis isomerization of lipophilic dyes is a useful parameter to monitor packaging and fluidity of biomembranes. Fluorescence fluctuations, generated by trans-cis isomerization of the thiocarbocyanine dye Merocyanine 540 (MC540), were first analyzed by fluorescence correlation spectroscopy (FCS) in different alcohol solutions. Similar isomerization kinetics of MC540 in lipid vesicles could then also be monitored, and the influence of lipid polarity, membrane curvature, and cholesterol content was investigated. While no influence of membrane curvature and lipid polarity could be observed, a clear decrease in the isomerization rates could be observed with increasing cholesterol contents in the vesicle membranes. Finally, procedures to spatially map photoinduced and thermal ...
Giant unilamellar vesicles (GUVs) have a wide range of applications in biology and synthetic biology. As a result, new approaches for constructing GUVs using microfluidic techniques are emerging but there are still significant shortcomings in the control of fundamental vesicle structural parameters such as s