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Sample records for primed vesicle state

  1. Synaptobrevin N-terminally bound to syntaxin–SNAP-25 defines the primed vesicle state in regulated exocytosis

    PubMed Central

    Walter, Alexander M.; Wiederhold, Katrin; Bruns, Dieter; Fasshauer, Dirk

    2010-01-01

    Rapid neurotransmitter release depends on the ability to arrest the SNAP receptor (SNARE)–dependent exocytosis pathway at an intermediate “cocked” state, from which fusion can be triggered by Ca2+. It is not clear whether this state includes assembly of synaptobrevin (the vesicle membrane SNARE) to the syntaxin–SNAP-25 (target membrane SNAREs) acceptor complex or whether the reaction is arrested upstream of that step. In this study, by a combination of in vitro biophysical measurements and time-resolved exocytosis measurements in adrenal chromaffin cells, we find that mutations of the N-terminal interaction layers of the SNARE bundle inhibit assembly in vitro and vesicle priming in vivo without detectable changes in triggering speed or fusion pore properties. In contrast, mutations in the last C-terminal layer decrease triggering speed and fusion pore duration. Between the two domains, we identify a region exquisitely sensitive to mutation, possibly constituting a switch. Our data are consistent with a model in which the N terminus of the SNARE complex assembles during vesicle priming, followed by Ca2+-triggered C-terminal assembly and membrane fusion. PMID:20142423

  2. Variable priming of a docked synaptic vesicle

    PubMed Central

    Jung, Jae Hoon; Szule, Joseph A.; Marshall, Robert M.; McMahan, Uel J.

    2016-01-01

    The priming of a docked synaptic vesicle determines the probability of its membrane (VM) fusing with the presynaptic membrane (PM) when a nerve impulse arrives. To gain insight into the nature of priming, we searched by electron tomography for structural relationships correlated with fusion probability at active zones of axon terminals at frog neuromuscular junctions. For terminals fixed at rest, the contact area between the VM of docked vesicles and PM varied >10-fold with a normal distribution. There was no merging of the membranes. For terminals fixed during repetitive evoked synaptic transmission, the normal distribution of contact areas was shifted to the left, due in part to a decreased number of large contact areas, and there was a subpopulation of large contact areas where the membranes were hemifused, an intermediate preceding complete fusion. Thus, fusion probability of a docked vesicle is related to the extent of its VM–PM contact area. For terminals fixed 1 h after activity, the distribution of contact areas recovered to that at rest, indicating the extent of a VM–PM contact area is dynamic and in equilibrium. The extent of VM–PM contact areas in resting terminals correlated with eccentricity in vesicle shape caused by force toward the PM and with shortness of active zone material macromolecules linking vesicles to PM components, some thought to include Ca2+ channels. We propose that priming is a variable continuum of events imposing variable fusion probability on each vesicle and is regulated by force-generating shortening of active zone material macromolecules in dynamic equilibrium. PMID:26858418

  3. Resident CAPS on dense-core vesicles docks and primes vesicles for fusion

    PubMed Central

    Kabachinski, Greg; Kielar-Grevstad, D. Michelle; Zhang, Xingmin; James, Declan J.; Martin, Thomas F. J.

    2016-01-01

    The Ca2+-dependent exocytosis of dense-core vesicles in neuroendocrine cells requires a priming step during which SNARE protein complexes assemble. CAPS (aka CADPS) is one of several factors required for vesicle priming; however, the localization and dynamics of CAPS at sites of exocytosis in live neuroendocrine cells has not been determined. We imaged CAPS before, during, and after single-vesicle fusion events in PC12 cells by TIRF micro­scopy. In addition to being a resident on cytoplasmic dense-core vesicles, CAPS was present in clusters of approximately nine molecules near the plasma membrane that corresponded to docked/tethered vesicles. CAPS accompanied vesicles to the plasma membrane and was present at all vesicle exocytic events. The knockdown of CAPS by shRNA eliminated the VAMP-2–dependent docking and evoked exocytosis of fusion-competent vesicles. A CAPS(ΔC135) protein that does not localize to vesicles failed to rescue vesicle docking and evoked exocytosis in CAPS-depleted cells, showing that CAPS residence on vesicles is essential. Our results indicate that dense-core vesicles carry CAPS to sites of exocytosis, where CAPS promotes vesicle docking and fusion competence, probably by initiating SNARE complex assembly. PMID:26700319

  4. Reconstituted synaptotagmin I mediates vesicle docking, priming, and fusion

    PubMed Central

    Wang, Zhao; Liu, Huisheng; Gu, Yiwen

    2011-01-01

    The synaptic vesicle protein synaptotagmin I (syt) promotes exocytosis via its ability to penetrate membranes in response to binding Ca2+ and through direct interactions with SNARE proteins. However, studies using full-length (FL) membrane-embedded syt in reconstituted fusion assays have yielded conflicting results, including a lack of effect, or even inhibition of fusion, by Ca2+. In this paper, we show that reconstituted FL syt promoted rapid docking of vesicles (<1 min) followed by a priming step (3–9 min) that was required for subsequent Ca2+-triggered fusion between v- and t-SNARE liposomes. Moreover, fusion occurred only when phosphatidylinositol 4,5-bisphosphate was included in the target membrane. This system also recapitulates some of the effects of syt mutations that alter synaptic transmission in neurons. Finally, we demonstrate that the cytoplasmic domain of syt exhibited mixed agonist/antagonist activity during regulated membrane fusion in vitro and in cells. Together, these findings reveal further convergence of reconstituted and cell-based systems. PMID:22184197

  5. Secretory vesicle priming by CAPS is independent of its SNARE-binding MUN domain.

    PubMed

    Nguyen Truong, Cuc Quynh; Nestvogel, Dennis; Ratai, Olga; Schirra, Claudia; Stevens, David R; Brose, Nils; Rhee, JeongSeop; Rettig, Jens

    2014-11-06

    Priming of secretory vesicles is a prerequisite for their Ca(2+)-dependent fusion with the plasma membrane. The key vesicle priming proteins, Munc13s and CAPSs, are thought to mediate vesicle priming by regulating the conformation of the t-SNARE syntaxin, thereby facilitating SNARE complex assembly. Munc13s execute their priming function through their MUN domain. Given that the MUN domain of Ca(2+)-dependent activator protein for secretion (CAPS) also binds syntaxin, it was assumed that CAPSs prime vesicles through the same mechanism as Munc13s. We studied naturally occurring splice variants of CAPS2 in CAPS1/CAPS2-deficient cells and found that CAPS2 primes vesicles independently of its MUN domain. Instead, the pleckstrin homology domain of CAPS2 seemingly is essential for its priming function. Our findings indicate a priming mode for secretory vesicles. This process apparently requires membrane phospholipids, does not involve the binding or direct conformational regulation of syntaxin by MUN domains of CAPSs, and is therefore not redundant with Munc13 action.

  6. The Vesicle Priming Factor CAPS Functions as a Homodimer via C2 Domain Interactions to Promote Regulated Vesicle Exocytosis*

    PubMed Central

    Petrie, Matt; Esquibel, Joseph; Maciuba, Stephanie; Takahashi, Hirohide

    2016-01-01

    Neurotransmitters and peptide hormones are secreted by regulated vesicle exocytosis. CAPS (also known as CADPS) is a 145-kDa cytosolic and peripheral membrane protein required for vesicle docking and priming steps that precede Ca2+-triggered vesicle exocytosis. CAPS binds phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and SNARE proteins and is proposed to promote SNARE protein complex assembly for vesicle docking and priming. We characterized purified soluble CAPS as mainly monomer in equilibrium with small amounts of dimer. However, the active form of CAPS bound to PC12 cell membranes or to liposomes containing PI(4,5)P2 and Q-SNARE proteins was mainly dimer. CAPS dimer formation required its C2 domain based on mutation or deletion studies. Moreover, C2 domain mutations or deletions resulted in a loss of CAPS function in regulated vesicle exocytosis, indicating that dimerization is essential for CAPS function. Comparison of the CAPS C2 domain to a structurally defined Munc13-1 C2A domain dimer revealed conserved residues involved in CAPS dimerization. We conclude that CAPS functions as a C2 domain-mediated dimer in regulated vesicle exocytosis. The unique tandem C2-PH domain of CAPS may serve as a PI(4,5)P2-triggered switch for dimerization. CAPS dimerization may be coupled to oligomeric SNARE complex assembly for vesicle docking and priming. PMID:27528604

  7. CAPS-1 and CAPS-2 are essential synaptic vesicle priming proteins.

    PubMed

    Jockusch, Wolf J; Speidel, Dina; Sigler, Albrecht; Sørensen, Jakob B; Varoqueaux, Frederique; Rhee, Jeong-Seop; Brose, Nils

    2007-11-16

    Before transmitter-filled synaptic vesicles can fuse with the plasma membrane upon stimulation they have to be primed to fusion competence. The regulation of this priming process controls the strength and plasticity of synaptic transmission between neurons, which in turn determines many complex brain functions. We show that CAPS-1 and CAPS-2 are essential components of the synaptic vesicle priming machinery. CAPS-deficient neurons contain no or very few fusion competent synaptic vesicles, which causes a selective impairment of fast phasic transmitter release. Increases in the intracellular Ca(2+) levels can transiently revert this defect. Our findings demonstrate that CAPS proteins generate and maintain a highly fusion competent synaptic vesicle pool that supports phasic Ca(2+) triggered release of transmitters.

  8. Two distinct secretory vesicle-priming steps in adrenal chromaffin cells.

    PubMed

    Liu, Yuanyuan; Schirra, Claudia; Edelmann, Ludwig; Matti, Ulf; Rhee, JeongSeop; Hof, Detlef; Bruns, Dieter; Brose, Nils; Rieger, Heiko; Stevens, David R; Rettig, Jens

    2010-09-20

    Priming of large dense-core vesicles (LDCVs) is a Ca(2+)-dependent step by which LDCVs enter a release-ready pool, involving the formation of the soluble N-ethyl-maleimide sensitive fusion protein attachment protein (SNAP) receptor complex consisting of syntaxin, SNAP-25, and synaptobrevin. Using mice lacking both isoforms of the calcium-dependent activator protein for secretion (CAPS), we show that LDCV priming in adrenal chromaffin cells entails two distinct steps. CAPS is required for priming of the readily releasable LDCV pool and sustained secretion in the continued presence of high Ca(2+) concentrations. Either CAPS1 or CAPS2 can rescue secretion in cells lacking both CAPS isoforms. Furthermore, the deficit in the readily releasable LDCV pool resulting from CAPS deletion is reversed by a constitutively open form of syntaxin but not by Munc13-1, a priming protein that facilitates the conversion of syntaxin to the open conformation. Our data indicate that CAPS functions downstream of Munc13s but also interacts functionally with Munc13s in the LDCV-priming process.

  9. Acute destruction of the synaptic ribbon reveals a role for the ribbon in vesicle priming

    PubMed Central

    Snellman, Josefin; Mehta, Bhupesh; Babai, Norbert; Bartoletti, Theodore M.; Akmentin, Wendy; Francis, Adam; Matthews, Gary; Thoreson, Wallace; Zenisek, David

    2011-01-01

    In vision, balance, and hearing, sensory receptor cells translate sensory stimuli into electrical signals whose amplitude is graded with stimulus intensity. The output synapses of these sensory neurons must provide fast signaling to follow rapidly changing stimuli, while also transmitting graded information covering a wide range of stimulus intensity and sustained for long time periods. To meet these demands, specialized machinery for transmitter release—the synaptic ribbon—has evolved at the synaptic outputs of these neurons. Here we show that acute disruption of synaptic ribbons by photodamage to the ribbon dramatically reduces both sustained and transient components of neurotransmitter release in mouse bipolar cells and salamander cones, without affecting the ultrastructure of the ribbon or its ability to localize synaptic vesicles to the active zone. Our results indicate that ribbons mediate slow as well as fast signaling at sensory synapses, and support an additional role for the synaptic ribbon in priming vesicles for exocytosis at active zones. PMID:21785435

  10. Synaptotagmin interaction with SNAP-25 governs vesicle docking, priming, and fusion triggering.

    PubMed

    Mohrmann, Ralf; de Wit, Heidi; Connell, Emma; Pinheiro, Paulo S; Leese, Charlotte; Bruns, Dieter; Davletov, Bazbek; Verhage, Matthijs; Sørensen, Jakob B

    2013-09-04

    SNARE complex assembly constitutes a key step in exocytosis that is rendered Ca(2+)-dependent by interactions with synaptotagmin-1. Two putative sites for synaptotagmin binding have recently been identified in SNAP-25 using biochemical methods: one located around the center and another at the C-terminal end of the SNARE bundle. However, it is still unclear whether and how synaptotagmin-1 × SNARE interactions at these sites are involved in regulating fast neurotransmitter release. Here, we have used electrophysiological techniques with high time-resolution to directly investigate the mechanistic ramifications of proposed SNAP-25 × synaptotagmin-1 interaction in mouse chromaffin cells. We demonstrate that the postulated central binding domain surrounding layer zero covers both SNARE motifs of SNAP-25 and is essential for vesicle docking, priming, and fast fusion-triggering. Mutation of this site caused no further functional alterations in synaptotagmin-1-deficient cells, indicating that the central acidic patch indeed constitutes a mechanistically relevant synaptotagmin-1 interaction site. Moreover, our data show that the C-terminal binding interface only plays a subsidiary role in triggering but is required for the full size of the readily releasable pool. Intriguingly, we also found that mutation of synaptotagmin-1 interaction sites led to more pronounced phenotypes in the context of the adult neuronal isoform SNAP-25B than in the embryonic isoform SNAP-25A. Further experiments demonstrated that stronger synaptotagmin-1 × SNAP-25B interactions allow for the larger primed vesicle pool supported by SNAP-25 isoform B. Thus, synaptotagmin-1 × SNARE interactions are not only required for multiple mechanistic steps en route to fusion but also underlie the developmental control of the releasable vesicle pool.

  11. Titration of Syntaxin1 in mammalian synapses reveals multiple roles in vesicle docking, priming, and release probability.

    PubMed

    Arancillo, Marife; Min, Sang-Won; Gerber, Stefan; Münster-Wandowski, Agnieszka; Wu, Yuan-Ju; Herman, Melissa; Trimbuch, Thorsten; Rah, Jong-Cheol; Ahnert-Hilger, Gudrun; Riedel, Dietmar; Südhof, Thomas C; Rosenmund, Christian

    2013-10-16

    Synaptic vesicles undergo sequential steps in preparation for neurotransmitter release. Individual SNARE proteins and the SNARE complex itself have been implicated in these processes. However, discrete effects of SNARE proteins on synaptic function have been difficult to assess using complete loss-of-function approaches. We therefore used a genetic titration technique in cultured mouse hippocampal neurons to evaluate the contribution of the neuronal SNARE protein Syntaxin1 (Stx1) in vesicle docking, priming, and release probability. We generated graded reductions of total Stx1 levels by combining two approaches, namely, endogenous hypomorphic expression of the isoform Stx1B and RNAi-mediated knockdown. Proximity of synaptic vesicles to the active zone was not strongly affected. However, overall release efficiency of affected neurons was severely impaired, as demonstrated by a smaller readily releasable pool size, slower refilling rate of primed vesicles, and lower release probability. Interestingly, dose-response fitting of Stx1 levels against readily releasable pool size and vesicular release probability showed similar Kd (dissociation constant) values at 18% and 19% of wild-type Stx1, with cooperativity estimates of 3.4 and 2.5, respectively. This strongly suggests that priming and vesicle fusion share the same molecular stoichiometry, and are governed by highly related mechanisms.

  12. Outer Membrane Vesicles Prime and Activate Macrophage Inflammasomes and Cytokine Secretion In Vitro and In Vivo

    PubMed Central

    Cecil, Jessica D.; O’Brien-Simpson, Neil M.; Lenzo, Jason C.; Holden, James A.; Singleton, William; Perez-Gonzalez, Alexis; Mansell, Ashley; Reynolds, Eric C.

    2017-01-01

    Outer membrane vesicles (OMVs) are proteoliposomes blebbed from the surface of Gram-negative bacteria. Chronic periodontitis is associated with an increase in subgingival plaque of Gram-negative bacteria, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. In this study, we investigated the immune-modulatory effects of P. gingivalis, T. denticola, and T. forsythia OMVs on monocytes and differentiated macrophages. All of the bacterial OMVs were phagocytosed by monocytes, M(naïve) and M(IFNγ) macrophages in a dose-dependent manner. They also induced NF-κB activation and increased TNFα, IL-8, and IL-1β cytokine secretion. P. gingivalis OMVs were also found to induce anti-inflammatory IL-10 secretion. Although unprimed monocytes and macrophages were resistant to OMV-induced cell death, lipopolysaccharide or OMV priming resulted in a significantly reduced cell viability. P. gingivalis, T. denticola, and T. forsythia OMVs all activated inflammasome complexes, as monitored by IL-1β secretion and ASC speck formation. ASC was critical for OMV-induced inflammasome formation, while AIM2−/− and Caspase-1−/− cells had significantly reduced inflammasome formation and NLRP3−/− cells exhibited a slight reduction. OMVs were also found to provide both priming and activation of the inflammasome complex. High-resolution microscopy and flow cytometry showed that P. gingivalis OMVs primed and activated macrophage inflammasomes in vivo with 80% of macrophages exhibiting inflammasome complex formation. In conclusion, periodontal pathogen OMVs were found to have significant immunomodulatory effects upon monocytes and macrophages and should therefore influence pro-inflammatory host responses associated with disease. PMID:28890719

  13. Extracellular Vesicles from Metastatic Rat Prostate Tumors Prime the Normal Prostate Tissue to Facilitate Tumor Growth

    PubMed Central

    Halin Bergström, Sofia; Hägglöf, Christina; Thysell, Elin; Bergh, Anders; Wikström, Pernilla; Lundholm, Marie

    2016-01-01

    Accumulating data indicates that tumor-derived extracellular vesicles (EVs) are responsible for tumor-promoting effects. However, if tumor EVs also prepare the tumor-bearing organ for subsequent tumor growth, and if this effect is different in low and high malignant tumors is not thoroughly explored. Here we used orthotopic rat Dunning R-3327 prostate tumors to compare the role of EVs from fast growing and metastatic MatLyLu (MLL) tumors with EVs from more indolent and non-metastatic Dunning G (G) tumors. Prostate tissue pre-conditioned with MLL-EVs in vivo facilitated G tumor establishment compared to G-EVs. MLL-EVs increased prostate epithelial proliferation and macrophage infiltration into the prostate compared to G-EVs. Both types of EVs increased macrophage endocytosis and the mRNA expression of genes associated with M2 polarization in vitro, with MLL-EVs giving the most pronounced effects. MLL-EVs also altered the mRNA expression of growth factors and cytokines in primary rat prostate fibroblasts compared to G-EVs, suggesting fibroblast activation. Our findings propose that EVs from metastatic tumors have the ability to prime the prostate tissue and enhance tumor growth to a higher extent than EVs from non-metastatic tumors. Identifying these differences could lead to novel therapeutic targets and potential prognostic markers for prostate cancer. PMID:27550147

  14. Vesicles

    MedlinePlus

    ... the top of a pin or up to 5 millimeters wide. A larger blister is called a bulla. In many cases, vesicles break easily and release their fluid onto the skin. When this fluid dries, yellow crusts may remain on the skin surface.

  15. Vesicle release probability and pre-primed pool at glutamatergic synapses in area CA1 of the rat neonatal hippocampus

    PubMed Central

    Hanse, Eric; Gustafsson, Bengt

    2001-01-01

    Factors determining the release probability were examined using whole-cell patch-clamp recording and minimal stimulation (10 impulses, 50 Hz) of individual glutamatergic synapses, containing single release sites, on pyramidal neurones in the CA1 region of hippocampal slices from neonatal rats. Release probability following the first action potential in the burst (P1) varied among the synapses from 0 to 0.87 (mean ± s.d.; 0.35 ± 0.28, n = 52) and the average release during the burst (burst pool) varied from 0.4 to 4.1 events (1.7 ± 0.85, n = 52). Heterogeneity in P1 did not co-vary with that of the burst pool. By selecting burst trials during which only one release event occurred, the vesicle release probability (Pves) at a release site could be determined. It was found to vary considerably among the synapses, from 0.04 to 0.94 (0.43 ± 0.28, n = 43). This heterogeneity correlated significantly with that of P1 such that more than half of the variation of P1 could be explained by a variation in Pves. The average number of vesicles directly available for release at the onset of the burst (the pre-primed pool) was estimated as the cumulative release up to that point in the burst where a second release event did not produce higher initial release probability than that found in trials where only one vesicle was released. The average pre-primed pool varied among the synapses from 0.4 to 2.1 (1.03 ± 0.42, n = 43). It co-varied significantly with that of P1 such that it could explain the remaining variation in P1. The difference between the burst pool and the pre-primed pool suggests the presence of a fast (< 100 ms), activity-dependent priming of vesicles. Some synapses (9/52) did not show any initial release (P1 = 0), but release occurred later during the burst (‘low frequency mute synapses’). Their behaviour was explained by an absence of a pre-primed pool. PMID:11230520

  16. Interactions Between SNAP-25 and Synaptotagmin-1 Are Involved in Vesicle Priming, Clamping Spontaneous and Stimulating Evoked Neurotransmission.

    PubMed

    Schupp, Melanie; Malsam, Jörg; Ruiter, Marvin; Scheutzow, Andrea; Wierda, Keimpe D B; Söllner, Thomas H; Sørensen, Jakob B

    2016-11-23

    Whether interactions between synaptotagmin-1 (syt-1) and the soluble NSF attachment protein receptors (SNAREs) are required during neurotransmission is debated. We examined five SNAP-25 mutations designed to interfere with syt-1 interactions. One mutation, D51/E52/E55A, targeted negative charges within region II of the primary interface (Zhou et al., 2015); two mutations targeted region I (D166A and D166/E170A) and one mutation targeted both (D51/E52/E55/D166A). The final mutation (D186/D193A) targeted C-terminal residues not expected to interact with syt-1. An in vitro assay showed that the region I, region II, and region I+II (D51/E52/E55/D166A) mutants markedly reduced the attachment between syt-1 and t-SNARE-carrying vesicles in the absence of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. In the presence of PI(4,5)P2, vesicle attachment was unaffected by mutation. When expressed in Snap-25-null mouse autaptic neurons, region I mutations reduced the size of the readily releasable pool of vesicles, whereas the region II mutation reduced vesicular release probability. Combining both in the D51/E52/E55/D166A mutation abrogated evoked release. These data point to a division of labor between region I (vesicle priming) and region II (evoked release). Spontaneous release was disinhibited by region I mutations and found to correlate with defective complexin (Cpx) clamping in an in vitro fusion assay, pointing to an interdependent role of synaptotagmin and Cpx in release clamping. Mutation in region II (D51/E52/E55A) also unclamped release, but this effect could be overcome by synaptotagmin overexpression, arguing against an obligatory role in clamping. We conclude that three synaptic release functions of syt-1, vesicle priming, spontaneous release clamping, and evoked release triggering, depend on direct SNARE complex interaction. The function of synaptotagmin-1 (syt-1):soluble NSF attachment protein receptor (SNARE) interactions during neurotransmission remains

  17. Chlorophyll a triplet-state ESR in frozen phosphatidylcholine vesicles

    SciTech Connect

    Hiromitsu, I.; Kevan, L.

    1988-05-19

    Photoexcited chlorophyll a (Chla) triplet state in rapidly frozen egg phosphatidylcholine (EPC) vesicles is investigated at 77 K by electron spin resonance (ESR) spectroscopy using light intensity modulation. The electron spin polarization (ESP) intensity is stronger for 0.2 mM Chla than for 1.0 mM Chla. The absolute values of the zero field splitting parameter, D, are 283 (+/-1) x 10/sup -4/ and 276 (+/-2) x 10/sup -4/ cm/sup -1/, and the average depopulation rates of the triplet state are 0.671 +/- 0.052 and 1.054 +/- 0.036 ms/sup -1/ for 0.2 mM Chla and 1.0 mM Chla, respectively. This difference can be consistently attributed to faster triplet-state migration between adjacent Chla's at the higher 1.0 mM Chla concentration. A characteristic migration time of 2.6 ms is obtained. The ESP pattern of the Chla triplet state in the frozen EPC vesicles resembles that in polycrystals more than that in glasses. This suggests that the local environment around Chla in the vesicles is more structured than in glasses.

  18. Vesicle dynamics in a confined Poiseuille flow: From steady state to chaos

    NASA Astrophysics Data System (ADS)

    Aouane, Othmane; Thiébaud, Marine; Benyoussef, Abdelilah; Wagner, Christian; Misbah, Chaouqi

    2014-09-01

    Red blood cells (RBCs) are the major component of blood, and the flow of blood is dictated by that of RBCs. We employ vesicles, which consist of closed bilayer membranes enclosing a fluid, as a model system to study the behavior of RBCs under a confined Poiseuille flow. We extensively explore two main parameters: (i) the degree of confinement of vesicles within the channel and (ii) the flow strength. Rich and complex dynamics for vesicles are revealed, ranging from steady-state shapes (in the form of parachute and slipper shapes) to chaotic dynamics of shape. Chaos occurs through a cascade of multiple periodic oscillations of the vesicle shape. We summarize our results in a phase diagram in the parameter plane (degree of confinement and flow strength). This finding highlights the level of complexity of a flowing vesicle in the small Reynolds number where the flow is laminar in the absence of vesicles and can be rendered turbulent due to elasticity of vesicles.

  19. Pseudomonas aeruginosa Outer Membrane Vesicles Triggered by Human Mucosal Fluid and Lysozyme Can Prime Host Tissue Surfaces for Bacterial Adhesion

    PubMed Central

    Metruccio, Matteo M. E.; Evans, David J.; Gabriel, Manal M.; Kadurugamuwa, Jagath L.; Fleiszig, Suzanne M. J.

    2016-01-01

    Pseudomonas aeruginosa is a leading cause of human morbidity and mortality that often targets epithelial surfaces. Host immunocompromise, or the presence of indwelling medical devices, including contact lenses, can predispose to infection. While medical devices are known to accumulate bacterial biofilms, it is not well understood why resistant epithelial surfaces become susceptible to P. aeruginosa. Many bacteria, including P. aeruginosa, release outer membrane vesicles (OMVs) in response to stress that can fuse with host cells to alter their function. Here, we tested the hypothesis that mucosal fluid can trigger OMV release to compromise an epithelial barrier. This was tested using tear fluid and corneal epithelial cells in vitro and in vivo. After 1 h both human tear fluid, and the tear component lysozyme, greatly enhanced OMV release from P. aeruginosa strain PAO1 compared to phosphate buffered saline (PBS) controls (∼100-fold). Transmission electron microscopy (TEM) and SDS-PAGE showed tear fluid and lysozyme-induced OMVs were similar in size and protein composition, but differed from biofilm-harvested OMVs, the latter smaller with fewer proteins. Lysozyme-induced OMVs were cytotoxic to human corneal epithelial cells in vitro and murine corneal epithelium in vivo. OMV exposure in vivo enhanced Ly6G/C expression at the corneal surface, suggesting myeloid cell recruitment, and primed the cornea for bacterial adhesion (∼4-fold, P < 0.01). Sonication disrupted OMVs retained cytotoxic activity, but did not promote adhesion, suggesting the latter required OMV-mediated events beyond cell killing. These data suggest that mucosal fluid induced P. aeruginosa OMVs could contribute to loss of epithelial barrier function during medical device-related infections. PMID:27375592

  20. Improved protection against tuberculosis after boosting the BCG-primed mice with subunit Ag 85a delivered through intact skin with deformable vesicles.

    PubMed

    Kumar, Gavish; Sharma, Neha; Gupta, Pushpa; Joshi, Beenu; Gupta, Umesh Datta; Cevc, Gregor; Chopra, Amla

    2016-01-20

    To improve vaccination against tuberculosis (TBC) with Bacillus Calmette-Guerin (BCG), we introduce novel, non-invasive, secondary immunisations relying on epicutaneous (e.c.) applications of the TBC subunit antigen, Ag 85a, associated with deformable carrier vesicles. Immuno-boosting with such antigen-vesicles recruits more CD11c positive cells into the draining murine lymph nodes, and typically stimulates, especially the proximal, immune cells more than immunogen injections. Non-invasive antigen application also protects mice better against an infection with TBC. Subcutaneous injections of vesicular Ag 85a into BCG-primed mice mainly yield IgG1 and IgG2a, indicative of a mixed Th1 and Th2 response. Conversely, transcutaneous immuno-boosts of such mice with a deformable vesicle-Ag 85a combination mainly generate serum IgA and IgG2a, indicative of an IgA facilitated, Th1-mediated, immune response. The Ag 85a specific antibody titres are generally low, but T lymphocytes also proliferate in the immunised mice. The new, partially non-invasive, vaccination method lowers the burden of pulmonary infection with M. tuberculosis. In mice immunised with Ag85a associated with deformable vesicles we measured 116× (e.c.) to 51× (s.c.) lower colony forming units number in spleen and 9× (e.c.) to 3× (s.c.) lower such number in lungs. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Triplet states of oxygen vacancy defects in α-quartz: Center \\bf{\\text{E}^{\\prime\\prime}_{9}}

    NASA Astrophysics Data System (ADS)

    Mashkovtsev, R. I.; Pan, Y.

    2014-08-01

    The paramagnetic E^{\\prime\\prime}_{9} center in triplet state occurring in electron-irradiated, synthetic α-quartz has been investigated by using electron paramagnetic resonance (EPR) spectroscopy. The primary spin Hamiltonian parameter matrices g, D and A (hyperfine interactions for five 29Si nuclei) have now been determined. The principal values and principal directions of D and A matrices allow us to suggest the structural model for this stable triplet defect. The E^{\\prime\\prime}_{9} center involves the two unpaired electrons located in the orbitals of two silicon atoms next to one oxygen vacancy each. Firm correlations between the spin Hamiltonian matrix principal axes and crystallographic directions have been attained.

  2. ELKS1 localizes the synaptic vesicle priming protein bMunc13-2 to a specific subset of active zones.

    PubMed

    Kawabe, Hiroshi; Mitkovski, Miso; Kaeser, Pascal S; Hirrlinger, Johannes; Opazo, Felipe; Nestvogel, Dennis; Kalla, Stefan; Fejtova, Anna; Verrier, Sophie E; Bungers, Simon R; Cooper, Benjamin H; Varoqueaux, Frederique; Wang, Yun; Nehring, Ralf B; Gundelfinger, Eckart D; Rosenmund, Christian; Rizzoli, Silvio O; Südhof, Thomas C; Rhee, Jeong-Seop; Brose, Nils

    2017-03-06

    Presynaptic active zones (AZs) are unique subcellular structures at neuronal synapses, which contain a network of specific proteins that control synaptic vesicle (SV) tethering, priming, and fusion. Munc13s are core AZ proteins with an essential function in SV priming. In hippocampal neurons, two different Munc13s-Munc13-1 and bMunc13-2-mediate opposite forms of presynaptic short-term plasticity and thus differentially affect neuronal network characteristics. We found that most presynapses of cortical and hippocampal neurons contain only Munc13-1, whereas ∼10% contain both Munc13-1 and bMunc13-2. Whereas the presynaptic recruitment and activation of Munc13-1 depends on Rab3-interacting proteins (RIMs), we demonstrate here that bMunc13-2 is recruited to synapses by the AZ protein ELKS1, but not ELKS2, and that this recruitment determines basal SV priming and short-term plasticity. Thus, synapse-specific interactions of different Munc13 isoforms with ELKS1 or RIMs are key determinants of the molecular and functional heterogeneity of presynaptic AZs.

  3. A Sequential Vesicle Pool Model with a Single Release Sensor and a Ca2+-Dependent Priming Catalyst Effectively Explains Ca2+-Dependent Properties of Neurosecretion

    PubMed Central

    Walter, Alexander M.; Pinheiro, Paulo S.; Verhage, Matthijs; Sørensen, Jakob B.

    2013-01-01

    Neurotransmitter release depends on the fusion of secretory vesicles with the plasma membrane and the release of their contents. The final fusion step displays higher-order Ca2+ dependence, but also upstream steps depend on Ca2+. After deletion of the Ca2+ sensor for fast release – synaptotagmin-1 – slower Ca2+-dependent release components persist. These findings have provoked working models involving parallel releasable vesicle pools (Parallel Pool Models, PPM) driven by alternative Ca2+ sensors for release, but no slow release sensor acting on a parallel vesicle pool has been identified. We here propose a Sequential Pool Model (SPM), assuming a novel Ca2+-dependent action: a Ca2+-dependent catalyst that accelerates both forward and reverse priming reactions. While both models account for fast fusion from the Readily-Releasable Pool (RRP) under control of synaptotagmin-1, the origins of slow release differ. In the SPM the slow release component is attributed to the Ca2+-dependent refilling of the RRP from a Non-Releasable upstream Pool (NRP), whereas the PPM attributes slow release to a separate slowly-releasable vesicle pool. Using numerical integration we compared model predictions to data from mouse chromaffin cells. Like the PPM, the SPM explains biphasic release, Ca2+-dependence and pool sizes in mouse chromaffin cells. In addition, the SPM accounts for the rapid recovery of the fast component after strong stimulation, where the PPM fails. The SPM also predicts the simultaneous changes in release rate and amplitude seen when mutating the SNARE-complex. Finally, it can account for the loss of fast- and the persistence of slow release in the synaptotagmin-1 knockout by assuming that the RRP is depleted, leading to slow and Ca2+-dependent fusion from the NRP. We conclude that the elusive ‘alternative Ca2+ sensor’ for slow release might be the upstream priming catalyst, and that a sequential model effectively explains Ca2+-dependent properties of

  4. Guilt by dissociation: guilt primes augment the relationship between dissociative tendencies and state dissociation.

    PubMed

    Rugens, Alex; Terhune, Devin Blair

    2013-03-30

    We examined the influence of guilt on the relationship between dissociative tendencies and state dissociation during mirror-gazing in a non-clinical sample. Dissociative tendencies correlated with state dissociation following guilt primes, but not after negative or neutral primes. This suggests that guilt augments the relationship between dissociative tendencies and state dissociation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  5. α-Synuclein Populates Both Elongated and Broken Helix States on Small Unilamellar Vesicles

    PubMed Central

    Lokappa, Sowmya Bekshe; Ulmer, Tobias S.

    2011-01-01

    The misfolding of the protein α-synuclein (αS) has been implicated in the molecular chain of events leading to Parkinson disease. Physiologically, αS undergoes a transition from a random coil to helical conformation upon encountering synaptic vesicle membranes. On analogous small unilamellar vesicles (SUVs), the conformation of αS is dominated by a single elongated αS helix. However, alternative broken helix states have been postulated, mandating experimental clarification. Here, the upper limit for the free energy difference between elongated and broken helix conformations on SUVs resembling synaptic vesicles was determined to be 1.2 ± 0.4 kcal/mol, which amounts to a population ratio of 7.6:1 between both states (12% broken helices). In response to helix breaks at different positions, αS rearranged in an opportunistic manner, thereby minimizing helix abrogations to as little as one to two turns. Enthalpy and entropy measurements of gel state SUV-αS interactions indicated that broken helix states retain the ability to relieve membrane-packing stress. Thus, broken helix states are a distinct physiological feature of the vesicle-bound αS state, making it a “checkered” protein of multiple parallel conformations. A continuous interconversion between structural states may contribute to pathological αS misfolding. PMID:21524999

  6. The Munc18-1 domain 3a hinge-loop controls syntaxin-1A nanodomain assembly and engagement with the SNARE complex during secretory vesicle priming

    PubMed Central

    Kasula, Ravikiran; Bademosi, Adekunle T.; Harper, Callista B.; Morrow, Isabel C.; Hosy, Eric; Collins, Brett M.; Choquet, Daniel

    2016-01-01

    Munc18-1 and syntaxin-1A control SNARE-dependent neuroexocytosis and are organized in nanodomains on the plasma membrane of neurons and neurosecretory cells. Deciphering the intra- and intermolecular steps via which they prepare secretory vesicles (SVs) for fusion is key to understanding neuronal and hormonal communication. Here, we demonstrate that expression of a priming-deficient mutant lacking 17 residues of the domain 3a hinge-loop (Munc18-1Δ317-333) in PC12 cells engineered to knockdown Munc18-1/2 markedly prolonged SV docking. Single-molecule analysis revealed nonhomogeneous diffusion of Munc18-1 and syntaxin-1A in and out of partially overlapping nanodomains. Whereas Munc18-1WT mobility increased in response to stimulation, syntaxin-1A became less mobile. These Munc18-1 and syntaxin-1A diffusional switches were blocked by the expression of Munc18-1Δ317-333, suggesting that a conformational change in the Munc18-1 hinge-loop controls syntaxin-1A and subsequent SNARE complex assembly. Accordingly, syntaxin-1A confinement was prevented by expression of botulinum neurotoxin type E. The Munc18-1 domain 3a hinge-loop therefore controls syntaxin-1A engagement into SNARE complex formation during priming. PMID:27646276

  7. Seed priming: state of the art and new perspectives.

    PubMed

    Paparella, S; Araújo, S S; Rossi, G; Wijayasinghe, M; Carbonera, D; Balestrazzi, Alma

    2015-08-01

    Priming applied to commercial seed lots is widely used by seed technologists to enhance seed vigour in terms of germination potential and increased stress tolerance. Priming can be also valuable to seed bank operators who need improved protocols of ex situ conservation of germplasm collections (crop and native species). Depending on plant species, seed morphology and physiology, different priming treatments can be applied, all of them triggering the so-called 'pre-germinative metabolism'. This physiological process takes place during early seed imbibition and includes the seed repair response (activation of DNA repair pathways and antioxidant mechanisms), essential to preserve genome integrity, ensuring proper germination and seedling development. The review provides an overview of priming technology, describing the range of physical-chemical and biological treatments currently available. Optimised priming protocols can be designed using the 'hydrotime concept' analysis which provides the theoretical bases for assessing the relationship between water potential and germination rate. Despite the efforts so far reported to further improve seed priming, novel ideas and cutting-edge investigations need to be brought into this technological sector of agri-seed industry. Multidisciplinary translational research combining digital, bioinformatic and molecular tools will significantly contribute to expand the range of priming applications to other relevant commercial sectors, e.g. the native seed market.

  8. Magnesium Adenosine 5[prime]-Triphosphate-Energized Transport of Glutathione-S-Conjugates by Plant Vacuolar Membrane Vesicles.

    PubMed

    Li, Z. S.; Zhao, Y.; Rea, P. A.

    1995-04-01

    By characterization of the uptake of glutathione-S-conjugates, principally dinitrophenyl-S-glutathione (DNP-GS), by vacuolar membrane vesicles, we demonstrate that a subset of energy-dependent transport processes in plants are not H+-coupled but instead are directly energized by MgATP. The most salient features of this transport pathway are: (a) its specific, obligate requirement for MgATP as energy source; (b) the necessity for hydrolysis of the [gamma]-phosphate of MgATP for uptake; (c) the insensitivity of uptake to uncouplers of the transtonoplast H+ gradient (carbonylcyanide 4-trifluoromethoxyphenylhydrazone, gramicidin-D, and NH4Cl); (d) its pronounced sensitivity to vanadate and partial inhibition by vinblastine and verapamil; (e) the lack of chemical modification of DNP-GS either during or after transport; (f) the capacity of S-conjugates of chloroacetanilide herbicides, such as metolachlor-GS, but not free herbicide, to inhibit uptake; and (g) the ability of vacuolar membrane vesicles purified from a broad range of plant species, including Arabidopsis, Beta, Vigna, and Zea, to mediate MgATP-dependent, H+-electrochemical potential difference-independent DNP-GS uptake. On the basis of these findings it is proposed that the transport of DNP-GS across the vacuolar membrane of plant cells is catalyzed by a glutathione-conjugate transporter that directly employs MgATP rather than the energy contained in the transtonoplast H+-electrochemical potential difference to drive uptake. The broad distribution of the vacuolar DNP-GS transporter and its inhibition by metolachlor-GS are consistent with the notion that it plays a general role in the vacuolar sequestration of glutathione-conjugable cytotoxic agents.

  9. Adhesion energy can regulate vesicle fusion and stabilize partially fused states.

    PubMed

    Long, Rong; Hui, Chung-Yuen; Jagota, Anand; Bykhovskaia, Maria

    2012-07-07

    Release of neurotransmitters from nerve terminals occurs by fusion of synaptic vesicles with the plasma membrane, and this process is highly regulated. Although major molecular components that control docking and fusion of vesicles to the synaptic membrane have been identified, the detailed mechanics of this process is not yet understood. We have developed a mathematical model that predicts how adhesion forces imposed by docking and fusion molecular machinery would affect the fusion process. We have computed the membrane stress that is produced by adhesion-driven vesicle bending and find that it is compressive. Further, our computations of the membrane curvature predict that strong adhesion can create a metastable state with a partially opened pore that would correspond to the 'kiss and run' release mode. Our model predicts that the larger the vesicle size, the more likely the metastable state with a transiently opened pore. These results contribute to understanding the mechanics of the fusion process, including possible clamping of the fusion by increasing molecular adhesion, and a balance between 'kiss and run' and full collapse fusion modes.

  10. Adhesion energy can regulate vesicle fusion and stabilize partially fused states

    PubMed Central

    Long, Rong; Hui, Chung-Yuen; Jagota, Anand; Bykhovskaia, Maria

    2012-01-01

    Release of neurotransmitters from nerve terminals occurs by fusion of synaptic vesicles with the plasma membrane, and this process is highly regulated. Although major molecular components that control docking and fusion of vesicles to the synaptic membrane have been identified, the detailed mechanics of this process is not yet understood. We have developed a mathematical model that predicts how adhesion forces imposed by docking and fusion molecular machinery would affect the fusion process. We have computed the membrane stress that is produced by adhesion-driven vesicle bending and find that it is compressive. Further, our computations of the membrane curvature predict that strong adhesion can create a metastable state with a partially opened pore that would correspond to the ‘kiss and run’ release mode. Our model predicts that the larger the vesicle size, the more likely the metastable state with a transiently opened pore. These results contribute to understanding the mechanics of the fusion process, including possible clamping of the fusion by increasing molecular adhesion, and a balance between ‘kiss and run’ and full collapse fusion modes. PMID:22258550

  11. Seeing emotions in the eyes - inverse priming effects induced by eyes expressing mental states.

    PubMed

    Wagenbreth, Caroline; Rieger, Julia; Heinze, Hans-Jochen; Zaehle, Tino

    2014-01-01

    Automatic emotional processing of faces and facial expressions gain more and more of relevance in terms of social communication. Among a variety of different primes, targets and tasks, whole face images and facial expressions have been used to affectively prime emotional responses. This study investigates whether emotional information provided solely in eye regions that display mental states can also trigger affective priming. Sixteen subjects answered a lexical decision task (LDT) coupled with an affective priming paradigm. Emotion-associated eye regions were extracted from photographs of faces and acted as primes, whereas targets were either words or pseudo-words. Participants had to decide whether the targets were real German words or generated pseudo-words. Primes and targets belonged to the emotional categories "fear," "disgust," "happiness," and "neutral." A general valence effect for positive words was observed: responses in the LDT were faster for target words of the emotional category happiness when compared to other categories. Importantly, pictures of emotional eye regions preceding the target words affected their subsequent classification. While we show a classical priming effect for neutral target words - with shorter RT for congruent compared to incongruent prime-target pairs- , we observed an inverse priming effect for fearful and happy target words - with shorter RT for incongruent compared to congruent prime-target pairs. These inverse priming effects were driven exclusively by specific prime-target pairs. Reduced facial emotional information is sufficient to induce automatic implicit emotional processing. The emotional-associated eye regions were processed with respect to their emotional valence and affected the performance on the LDT.

  12. [Medical doctors as the state presidents and prime ministers--a biographical analysis].

    PubMed

    Lass, Piotr; Szarszewski, Adam; Gaworska-Krzemińska, Aleksandra; Sławek, Jarosław

    2012-01-01

    The authors overviewed the biographies of 29 medical doctors who became the heads of the state or the prime ministers of their countries. Most of them ruled in a countries of fresh or unstable democracies, most often in Asia, Africa and Latin America, three of them were bloody dictators. With the exemptions of Georges Clemenceau and Sun-Yat-Sen they were not famous as historical figures, although some were good administrators like the prime minister of Norway, Gro Harlem Brundtland, Malayan prime minister Mahatir bin Mohamad, Brasilian and Chilean presidents, Juscelino Kubitschek and Veronica Bachelet. Regarding specialisation was mostly general medics or they specialised in public health.

  13. Symmetric Informationally-Complete States Are Minimum Uncertainty States in Prime Dimensions

    NASA Astrophysics Data System (ADS)

    Bui Dang, Hoan; Appleby, Marcus; Fuchs, Christopher

    2010-03-01

    Symmetric informationally-complete (SIC) sets of quantum states have received growing attention due to their many nice properties. For prime dimensions, we add another property to the list: Weyl-Heisenberg covariant SIC states achieve minimum uncertainty (in a sense defined independently by the authors [1] and Wootters and Sussman [2]) with respect to a complete set of mutually unbiased bases. In this way, SIC states can be considered as finite-dimensional analogues to coherent states. Because of an observation in [2], measurements based on these states are particularly important for quantum eavesdropping in generalized BB84 quantum key distribution schemes. References: [1] D. M. Appleby, H. B. Dang, and C. A. Fuchs, ``Symmetric Informationally-Complete Quantum States as Analogues to Orthonormal Bases and Minimum-Uncertainty States,'' arXiv:0707.2071v1 [quant-ph]. [2] D. Sussman and W. K. Wootters, ``Discrete Phase Space and Minimum-Uncertainty States,'' arXiv:0704.1277v1 [quant-ph].

  14. Qualitative changes in the proteome of extracellular vesicles accompanying cancer cell transition to mesenchymal state.

    PubMed

    Garnier, Delphine; Magnus, Nathalie; Meehan, Brian; Kislinger, Thomas; Rak, Janusz

    2013-10-15

    Transitions of the cancer cell phenotype between epithelial and mesenchymal states (EMT) are likely to alter the patterns of intercellular communication. In this regard we have previously documented that EMT-like changes trigger quantitative rearrangements in exosomal vesicle emission in A431 cancer cells driven by oncogenic epidermal growth factor receptor (EGFR). Here we report that extracellular vesicles (EVs) produced by these cancer cells in their epithelial and mesenchymal states exhibit profound qualitative differences in their proteome. Thus, induction of the EMT-like state through blockade of E-cadherin and EGFR stimulation provoked a mesenchymal shift in cellular morphology and enrichment in the CD44-high/CD24-low immunophenotype, often linked to cellular stemness. This change also resulted in reprogramming of the EV-related proteome (distinct from that of corresponding cells), which contained 30 unique protein signals, and revealed enrichment in pathways related to cellular growth, cell-to-cell signaling, and cell movement. Some of the most prominent EV-related proteins were validated, including integrin α2 and tetraspanin CD9. We propose that changes in cellular differentiation status translate into unique qualitative rearrangements in the cargo of EVs, a process that may have implications for intercellular communication and could serve as source of new biomarkers to detect EMT-like processes in cancer.

  15. Detection and Trapping of Intermediate States Priming Nicotinic Receptor Channel Opening

    PubMed Central

    Mukhtasimova, Nuriya; Lee, Won Yong; Wang, Hai-Long; Sine, Steven M.

    2009-01-01

    In the course of synaptic transmission in the brain and periphery, acetylcholine receptors (AChRs) rapidly transduce a chemical signal into an electrical impulse. The speed of transduction owes in large part to rapid ACh association and dissociation, implying a binding site relatively non-selective for small cations; selective transduction has been supposed to originate from the ability of ACh, over that of other organic cations, to trigger the subsequent channel opening step. However transitions to and from the open state were shown to be similar for agonists with widely different efficacies.1,2,3 Here, by studying mutant AChRs, we find that the ultimate closed to open transition is agonist-independent and preceded by two primed closed states; the first primed state elicits brief openings, whereas the second elicits long-lived openings. Long-lived openings and the associated primed state are detected in the absence and presence of agonist, and exhibit the same kinetic signatures under both conditions. By covalently locking the agonist binding sites in the bound conformation, we find that each site initiates a priming step. Thus a change in binding site conformation primes the AChR for channel opening in a process that enables selective activation by ACh while maximizing speed and efficiency of the biological response. PMID:19339970

  16. Vesicle Pools: Lessons from Adrenal Chromaffin Cells

    PubMed Central

    Stevens, David R.; Schirra, Claudia; Becherer, Ute; Rettig, Jens

    2011-01-01

    The adrenal chromaffin cell serves as a model system to study fast Ca2+-dependent exocytosis. Membrane capacitance measurements in combination with Ca2+ uncaging offers a temporal resolution in the millisecond range and reveals that catecholamine release occurs in three distinct phases. Release of a readily releasable (RRP) and a slowly releasable (SRP) pool are followed by sustained release, due to maturation, and release of vesicles which were not release-ready at the start of the stimulus. Trains of depolarizations, a more physiological stimulus, induce release from a small immediately releasable pool of vesicles residing adjacent to calcium channels, as well as from the RRP. The SRP is poorly activated by depolarization. A sequential model, in which non-releasable docked vesicles are primed to a slowly releasable state, and then further mature to the readily releasable state, has been proposed. The docked state, dependent on membrane proximity, requires SNAP-25, synaptotagmin, and syntaxin. The ablation or modification of SNAP-25 and syntaxin, components of the SNARE complex, as well as of synaptotagmin, the calcium sensor, and modulators such complexins and Snapin alter the properties and/or magnitudes of different phases of release, and in particular can ablate the RRP. These results indicate that the composition of the SNARE complex and its interaction with modulatory molecules drives priming and provides a molecular basis for different pools of releasable vesicles. PMID:21423410

  17. Subdiffractional tracking of internalized molecules reveals heterogeneous motion states of synaptic vesicles.

    PubMed

    Joensuu, Merja; Padmanabhan, Pranesh; Durisic, Nela; Bademosi, Adekunle T D; Cooper-Williams, Elizabeth; Morrow, Isabel C; Harper, Callista B; Jung, WooRam; Parton, Robert G; Goodhill, Geoffrey J; Papadopulos, Andreas; Meunier, Frédéric A

    2016-10-24

    Our understanding of endocytic pathway dynamics is severely restricted by the diffraction limit of light microscopy. To address this, we implemented a novel technique based on the subdiffractional tracking of internalized molecules (sdTIM). This allowed us to image anti-green fluorescent protein Atto647N-tagged nanobodies trapped in synaptic vesicles (SVs) from live hippocampal nerve terminals expressing vesicle-associated membrane protein 2 (VAMP2)-pHluorin with 36-nm localization precision. Our results showed that, once internalized, VAMP2-pHluorin/Atto647N-tagged nanobodies exhibited a markedly lower mobility than on the plasma membrane, an effect that was reversed upon restimulation in presynapses but not in neighboring axons. Using Bayesian model selection applied to hidden Markov modeling, we found that SVs oscillated between diffusive states or a combination of diffusive and transport states with opposite directionality. Importantly, SVs exhibiting diffusive motion were relatively less likely to switch to the transport motion. These results highlight the potential of the sdTIM technique to provide new insights into the dynamics of endocytic pathways in a wide variety of cellular settings.

  18. Reductive quenching of the excited states of ruthenium(II) complexes containing 2,2[prime]-bipyridine, 2,2[prime]-bipyrazine, and 2,2[prime]-bipyrimidine ligands

    SciTech Connect

    Sun, H.; Hoffman, M.Z. )

    1994-11-10

    The reductive quenching of the luminescent excited states of Ru(II) complexes of the general formula Ru-(bpy)[sub 3-m-z](bpm)[sub m](bpz)[sub z][sup 2+] (bpy = 2,2[prime]-bipyridine, bpm = 2,2[prime]-bipyrimidine, bpz = 2,2[prime]-bipyrazine, m and z = 0, 1,2,3 and m + z [le] 3) by aromatic amines and methoxybenzenes as nonsacrificial electron donors and by C[sub 2]O[sub 4][sup 2[minus

  19. Translation-priming effects on tip-of-the-tongue states

    PubMed Central

    Gollan, Tamar H.; Ferreira, Victor S.; Cera, Cynthia; Flett, Susanna

    2013-01-01

    Bilinguals experience more tip-of-the-tongue (TOT) states than monolinguals, but it is not known if this is caused in part by access of representations from both of bilinguals’ languages, or dual-language activation. In two translation priming experiments, bilinguals were given three Spanish primes and produced either semantically (Experiment 1) or phonologically related Spanish words (Experiment 2) to each. They then named a picture in English. On critical trials, one of the primes was the Spanish translation of the English picture name. Translation primes significantly increased TOTs regardless of task, and also speeded correct retrievals but only with the semantic task. In both experiments translation-primed TOTs were significantly more likely to resolve spontaneously. These results illustrate an effect of non-dominant language activation on dominant-language retrieval, as well as imply that TOTs can arise during (not after) lexical retrieval, at a level of processing where translation equivalent lexical representations normally interact (possibly competing for selection, or mutually activating each other, or both depending on the locus of retrieval failure). PMID:24644375

  20. Synaptotagmin-7 Is Essential for Ca2+-Triggered Delayed Asynchronous Release But Not for Ca2+-Dependent Vesicle Priming in Retinal Ribbon Synapses

    PubMed Central

    Bacaj, Taulant

    2015-01-01

    Most synapses release neurotransmitters in two phases: (1) a fast synchronous phase lasting a few milliseconds; and (2) a delayed “asynchronous” phase lasting hundreds of milliseconds. Ca2+ triggers fast synchronous neurotransmitter release by binding to synaptotagmin-1, synaptotagmin-2, or synaptotagmin-9, but how Ca2+ triggers delayed asynchronous release has long remained enigmatic. Recent results suggested that consistent with the Ca2+-sensor function of synaptotagmin-7 in neuroendocrine exocytosis, synaptotagmin-7 also functions as a Ca2+ sensor for synaptic vesicle exocytosis but operates during delayed asynchronous release. Puzzlingly, a subsequent study postulated that synaptotagmin-7 is not a Ca2+ sensor for release but mediates Ca2+-dependent vesicle repriming after intense stimulation. To address these issues, we here analyzed synaptic transmission at rod bipolar neuron–AII amacrine cell synapses in acute mouse retina slices as a model system. Using paired recordings, we show that knock-out of synaptotagmin-7 selectively impairs delayed asynchronous release but not fast synchronous release. Delayed asynchronous release was blocked in wild-type synapses by intracellular addition of high concentrations of the slow Ca2+-chelator EGTA, but EGTA had no effect in synaptotagmin-7 knock-out neurons because delayed asynchronous release was already impaired. Moreover, direct measurements of vesicle repriming failed to uncover an effect of the synaptotagmin-7 knock-out on vesicle repriming. Our data demonstrate that synaptotagmin-7 is selectively essential for Ca2+-dependent delayed asynchronous release in retinal rod bipolar cell synapses, that its function can be blocked by simply introducing a slow Ca2+ buffer into the cells, and that synaptotagmin-7 is not required for normal vesicle repriming. SIGNIFICANCE STATEMENT How Ca2+ triggers delayed asynchronous release has long remained enigmatic. Synaptotagmin-7 has been implicated recently as Ca2+ sensor in

  1. Synaptotagmin-7 Is Essential for Ca2+-Triggered Delayed Asynchronous Release But Not for Ca2+-Dependent Vesicle Priming in Retinal Ribbon Synapses.

    PubMed

    Luo, Fujun; Bacaj, Taulant; Südhof, Thomas C

    2015-08-05

    Most synapses release neurotransmitters in two phases: (1) a fast synchronous phase lasting a few milliseconds; and (2) a delayed "asynchronous" phase lasting hundreds of milliseconds. Ca(2+) triggers fast synchronous neurotransmitter release by binding to synaptotagmin-1, synaptotagmin-2, or synaptotagmin-9, but how Ca(2+) triggers delayed asynchronous release has long remained enigmatic. Recent results suggested that consistent with the Ca(2+)-sensor function of synaptotagmin-7 in neuroendocrine exocytosis, synaptotagmin-7 also functions as a Ca(2+) sensor for synaptic vesicle exocytosis but operates during delayed asynchronous release. Puzzlingly, a subsequent study postulated that synaptotagmin-7 is not a Ca(2+) sensor for release but mediates Ca(2+)-dependent vesicle repriming after intense stimulation. To address these issues, we here analyzed synaptic transmission at rod bipolar neuron-AII amacrine cell synapses in acute mouse retina slices as a model system. Using paired recordings, we show that knock-out of synaptotagmin-7 selectively impairs delayed asynchronous release but not fast synchronous release. Delayed asynchronous release was blocked in wild-type synapses by intracellular addition of high concentrations of the slow Ca(2+)-chelator EGTA, but EGTA had no effect in synaptotagmin-7 knock-out neurons because delayed asynchronous release was already impaired. Moreover, direct measurements of vesicle repriming failed to uncover an effect of the synaptotagmin-7 knock-out on vesicle repriming. Our data demonstrate that synaptotagmin-7 is selectively essential for Ca(2+)-dependent delayed asynchronous release in retinal rod bipolar cell synapses, that its function can be blocked by simply introducing a slow Ca(2+) buffer into the cells, and that synaptotagmin-7 is not required for normal vesicle repriming. How Ca(2+) triggers delayed asynchronous release has long remained enigmatic. Synaptotagmin-7 has been implicated recently as Ca(2+) sensor in

  2. The Cumulative Effects of Indiana PRIME TIME: A State Sponsored Reduced Class Size Program, on Basic Skills Achievement.

    ERIC Educational Resources Information Center

    Malloy, Leanne; Gilman, David

    The purpose of this paper was to analyze the initial results of statewide implementation of the PRIME TIME program in Indiana. PRIME TIME is a state-wide program to reduce class size in the primary grades. Mean scores from 65,911 third graders who had completed the Indiana Competency Test in the spring of 1987 after completing 3 years of the…

  3. Prime Knowledge about Primes

    ERIC Educational Resources Information Center

    Eisenberg, Theodore

    2007-01-01

    Several proofs demonstrating that there are infinitely many primes, different types of primes, tests of primality, pseudo primes, prime number generators and open questions about primes are discussed in Section 1. Some of these notions are elaborated upon in Section 2, with discussions of the Riemann zeta function and how algorithmic complexity…

  4. Prime Knowledge about Primes

    ERIC Educational Resources Information Center

    Eisenberg, Theodore

    2007-01-01

    Several proofs demonstrating that there are infinitely many primes, different types of primes, tests of primality, pseudo primes, prime number generators and open questions about primes are discussed in Section 1. Some of these notions are elaborated upon in Section 2, with discussions of the Riemann zeta function and how algorithmic complexity…

  5. Additive effects on the energy barrier for synaptic vesicle fusion cause supralinear effects on the vesicle fusion rate.

    PubMed

    Schotten, Sebastiaan; Meijer, Marieke; Walter, Alexander Matthias; Huson, Vincent; Mamer, Lauren; Kalogreades, Lawrence; ter Veer, Mirelle; Ruiter, Marvin; Brose, Nils; Rosenmund, Christian; Sørensen, Jakob Balslev; Verhage, Matthijs; Cornelisse, Lennart Niels

    2015-04-14

    The energy required to fuse synaptic vesicles with the plasma membrane ('activation energy') is considered a major determinant in synaptic efficacy. From reaction rate theory, we predict that a class of modulations exists, which utilize linear modulation of the energy barrier for fusion to achieve supralinear effects on the fusion rate. To test this prediction experimentally, we developed a method to assess the number of releasable vesicles, rate constants for vesicle priming, unpriming, and fusion, and the activation energy for fusion by fitting a vesicle state model to synaptic responses induced by hypertonic solutions. We show that complexinI/II deficiency or phorbol ester stimulation indeed affects responses to hypertonic solution in a supralinear manner. An additive vs multiplicative relationship between activation energy and fusion rate provides a novel explanation for previously observed non-linear effects of genetic/pharmacological perturbations on synaptic transmission and a novel interpretation of the cooperative nature of Ca(2+)-dependent release.

  6. Information on State versus Local Administration of CETA Prime Sponsors in Michigan. Report to the Chairman, Committee on Education and Labor, House of Representatives.

    ERIC Educational Resources Information Center

    General Accounting Office, Washington, DC. Div. of Human Resources.

    State administration of the Comprehensive Employment and Training Act (CETA) Balance of State (BOS) programs was compared with administration of CETA programs by local (regular) prime sponsors in Michigan to gain insight on the potential impact of increased state control. BOS prime sponsors spent less than regular prime sponsors for administration…

  7. Characterization and genetic manipulation of primed stem cells into a functional naïve state with ESRRB

    PubMed Central

    Rossello, Ricardo Antonio; Pfenning, Andreas; Howard, Jason T; Hochgeschwender, Ute

    2016-01-01

    AIM To identify differences between primed mouse embryonic stem cells (ESCs) and fully functional naive ESCs; to manipulate primed cells into a naive state. METHODS We have cultured 3 lines of cells from different mouse strains that have been shown to be naive or primed as determined by generating germline-transmitting chimeras. Cells were put through a battery of tests to measure the different features. RNA from cells was analyzed using microarrays, to determine a priority list of the differentially expressed genes. These were later validated by quantificational real-time polymerase chain reaction. Viral cassettes were created to induce expression of differentially expressed genes in the primed cells through lentiviral transduction. Primed reprogrammed cells were subjected to in-vivo incorporation studies. RESULTS Most results show that both primed and naive cells have similar features (morphology, proliferation rates, stem cell genes expressed). However, there were some genes that were differentially expressed in the naïve cells relative to the primed cells. Key upregulated genes in naïve cells include ESRRB, ERAS, ATRX, RNF17, KLF-5, and MYC. After over-expressing some of these genes the primed cells were able to incorporate into embryos in-vivo, re-acquiring a feature previously absent in these cells. CONCLUSION Although there are no notable phenotypic differences, there are key differences in gene expression between these naïve and primed stem cells. These differences can be overcome through overexpression. PMID:27822342

  8. Vesicle Photonics

    SciTech Connect

    Vasdekis, Andreas E.; Scott, E. A.; Roke, Sylvie; Hubbell, J. A.; Psaltis, D.

    2013-04-03

    Thin membranes, under appropriate boundary conditions, can self-assemble into vesicles, nanoscale bubbles that encapsulate and hence protect or transport molecular payloads. In this paper, we review the types and applications of light fields interacting with vesicles. By encapsulating light-emitting molecules (e.g. dyes, fluorescent proteins, or quantum dots), vesicles can act as particles and imaging agents. Vesicle imaging can take place also under second harmonic generation from vesicle membrane, as well as employing mass spectrometry. Light fields can also be employed to transport vesicles using optical tweezers (photon momentum) or directly pertrurbe the stability of vesicles and hence trigger the delivery of the encapsulated payload (photon energy).

  9. Graph states of prime-power dimension from generalized CNOT quantum circuit

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Zhou, D. L.

    2016-06-01

    We construct multipartite graph states whose dimension is the power of a prime number. This is realized by the finite field, as well as the generalized controlled-NOT quantum circuit acting on two qudits. We propose the standard form of graph states up to local unitary transformations and particle permutations. The form greatly simplifies the classification of graph states as we illustrate up to five qudits. We also show that some graph states are multipartite maximally entangled states in the sense that any bipartition of the system produces a bipartite maximally entangled state. We further prove that 4-partite maximally entangled states exist when the dimension is an odd number at least three or a multiple of four.

  10. Graph states of prime-power dimension from generalized CNOT quantum circuit

    PubMed Central

    Chen, Lin; Zhou, D. L.

    2016-01-01

    We construct multipartite graph states whose dimension is the power of a prime number. This is realized by the finite field, as well as the generalized controlled-NOT quantum circuit acting on two qudits. We propose the standard form of graph states up to local unitary transformations and particle permutations. The form greatly simplifies the classification of graph states as we illustrate up to five qudits. We also show that some graph states are multipartite maximally entangled states in the sense that any bipartition of the system produces a bipartite maximally entangled state. We further prove that 4-partite maximally entangled states exist when the dimension is an odd number at least three or a multiple of four. PMID:27272401

  11. Graph states of prime-power dimension from generalized CNOT quantum circuit.

    PubMed

    Chen, Lin; Zhou, D L

    2016-06-07

    We construct multipartite graph states whose dimension is the power of a prime number. This is realized by the finite field, as well as the generalized controlled-NOT quantum circuit acting on two qudits. We propose the standard form of graph states up to local unitary transformations and particle permutations. The form greatly simplifies the classification of graph states as we illustrate up to five qudits. We also show that some graph states are multipartite maximally entangled states in the sense that any bipartition of the system produces a bipartite maximally entangled state. We further prove that 4-partite maximally entangled states exist when the dimension is an odd number at least three or a multiple of four.

  12. Superpriming of synaptic vesicles after their recruitment to the readily releasable pool

    PubMed Central

    Lee, Jae Sung; Ho, Won-Kyung; Neher, Erwin; Lee, Suk-Ho

    2013-01-01

    Recruitment of release-competent vesicles during sustained synaptic activity is one of the major factors governing short-term plasticity. During bursts of synaptic activity, vesicles are recruited to a fast-releasing pool from a reluctant vesicle pool through an actin-dependent mechanism. We now show that newly recruited vesicles in the fast-releasing pool do not respond at full speed to a strong Ca2+ stimulus, but require approximately 4 s to mature to a “superprimed” state. Superpriming was found to be altered by agents that modulate the function of unc13 homolog proteins (Munc13s), but not by calmodulin inhibitors or actin-disrupting agents. These findings indicate that recruitment and superpriming of vesicles are regulated by separate mechanisms, which require integrity of the cytoskeleton and activation of Munc13s, respectively. We propose that refilling of the fast-releasing vesicle pool proceeds in two steps, rapid actin-dependent “positional priming,” which brings vesicles closer to Ca2+ sources, followed by slower superpriming, which enhances the Ca2+ sensitivity of primed vesicles. PMID:23980146

  13. SNARE-Mediated Lipid Mixing Depends on the Physical State of the Vesicles

    PubMed Central

    Chen, Xiaocheng; Araç, Demet; Wang, Tzu-Ming; Gilpin, Christopher J.; Zimmerberg, Joshua; Rizo, Josep

    2006-01-01

    Reconstitution experiments have suggested that N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) proteins constitute a minimal membrane fusion machinery but have yielded contradictory results, and it is unclear whether the mechanism of membrane merger is related to the stalk mechanism that underlies physiological membrane fusion. Here we show that reconstitution of solubilized neuronal SNAREs into preformed 100 nm liposomes (direct method) yields proteoliposomes with more homogeneous sizes and protein densities than the standard reconstitution method involving detergent cosolubilization of proteins and lipids. Standard reconstitutions yield slow but efficient lipid mixing at high protein densities and variable amounts of lipid mixing at moderate protein densities. However, the larger, more homogenous proteoliposomes prepared by the direct method yield almost no lipid mixing at moderate protein densities. These results suggest that the lipid mixing observed for standard reconstitutions is dominated by the physical state of the membrane, perhaps due to populations of small vesicles (or micelles) with high protein densities and curvature stress created upon reconstitution. Accordingly, changing membrane spontaneous curvature by adding lysophospholipids inhibits the lipid mixing observed for standard reconstitutions. Our data indicate that the lipid mixing caused by high SNARE densities and/or curvature stress occurs by a stalk mechanism resembling the mechanism of fusion between biological membranes, but the neuronal SNAREs are largely unable to induce lipid mixing at physiological protein densities and limited curvature stress. PMID:16361343

  14. Effect of water-soluble polymers on the state of aggregation, vesicle size, and phase transformations in mixtures of phosphatidylcholine and sodium cholate.

    PubMed Central

    Meyuhas, D; Lichtenberg, D

    1996-01-01

    The state of aggregation and the steady-state size of mixed aggregates made of phospholipids and surfactants are both determined by the surfactant/lipid ratio in the mixed aggregates (Re). Water-soluble polymers, such as dextrans and polyethylene glycols (PEGs) of different molecular weights, induce reversible aggregation of phospholipid vesicles, mostly due to dehydration of the vesicle surface and depletion forces, and only at much higher concentrations, PEGs (but not dextran) also induce irreversible size growth of the vesicles. Here we show that the water-soluble polymers dextrans and PEGs do not affect the vesicle-micelle phase boundaries in mixtures of phosphatidylcholine and the anionic surfactant sodium cholate. By contrast, these polymers affect markedly the steady-state size of cholate-containing vesicles. As compared with pure phosphatidylcholine vesicles, the cholate-containing vesicles have a lower tendency to undergo polymer-induced aggregation, probably due to the electrostatic repulsion between the negatively charged vesicles, but a higher tendency to undergo irreversible size growth at relatively low polymer concentrations. Such irreversible size growth was observed not only for PEG but also for dextran, which in the absence of cholate is incapable of inducing vesicle size growth. These findings are consistent with the prevailing concept that the polymer-induced size growth is due to the effect of large structural fluctuations in the bilayers of deformed aggregated vesicles, the surface of which is dehydrated by the polymer. The presence of cholate in the bilayers at sufficiently high concentrations induces such fluctuations, yielding irreversible size growth within the clusters of dehydrated vesicles formed upon mixing with polymers. Images FIGURE 2 PMID:8913599

  15. Convergent mechanisms mediate preparatory states and repetition priming in the feeding network of Aplysia.

    PubMed

    Proekt, Alex; Weiss, Klaudiusz R

    2003-05-15

    Improvement of behavioral responses to expected stimuli has been attributed to a change in the preparatory state. In this study, we take advantage of the accessibility of the nervous system of Aplysia and develop an in vitro analog of the preparatory state for feeding behaviors. We provide evidence that the change in the preparatory state may be elicited initially by activity of identified serotonergic metacerebral cells (MCCs). We demonstrate, however, that the preparatory state is maintained through MCC-independent repetition priming that is embedded in the properties of the behavior-generating network. Both MCC-dependent and MCC-independent processes converge on the same site in the behavior-generating network to mediate the change in the preparatory state. Thus, we propose a model of how multiple neuronal structures interact to elicit and maintain changes in the preparatory states in the CNS.

  16. Profiling of Altered Metabolomic States in Nicotiana tabacum Cells Induced by Priming Agents

    PubMed Central

    Mhlongo, Msizi I.; Steenkamp, Paul A.; Piater, Lizelle A.; Madala, Ntakadzeni E.; Dubery, Ian A.

    2016-01-01

    Metabolomics has developed into a valuable tool for advancing our understanding of plant metabolism. Plant innate immune defenses can be activated and enhanced so that, subsequent to being pre-sensitized, plants are able to launch a stronger and faster defense response upon exposure to pathogenic microorganisms, a phenomenon known as priming. Here, three contrasting chemical activators, namely acibenzolar-S-methyl, azelaic acid and riboflavin, were used to induce a primed state in Nicotiana tabacum cells. Identified biomarkers were then compared to responses induced by three phytohormones—abscisic acid, methyljasmonate, and salicylic acid. Altered metabolomes were studied using a metabolite fingerprinting approach based on liquid chromatography and mass spectrometry. Multivariate data models indicated that these inducers cause time-dependent metabolic perturbations in the cultured cells and revealed biomarkers of which the levels are affected by these agents. A total of 34 metabolites were annotated from the mass spectral data and online databases. Venn diagrams were used to identify common biomarkers as well as those unique to a specific agent. Results implicate 20 cinnamic acid derivatives conjugated to (i) quinic acid (chlorogenic acids), (ii) tyramine, (iii) polyamines, or (iv) glucose as discriminatory biomarkers of priming in tobacco cells. Functional roles for most of these metabolites in plant defense responses could thus be proposed. Metabolites induced by the activators belong to the early phenylpropanoid pathway, which indicates that different stimuli can activate similar pathways but with different metabolite fingerprints. Possible linkages to phytohormone-dependent pathways at a metabolomic level were indicated in the case of cells treated with salicylic acid and methyljasmonate. The results contribute to a better understanding of the priming phenomenon and advance our knowledge of cinnamic acid derivatives as versatile defense metabolites. PMID

  17. Magic-State Distillation in All Prime Dimensions Using Quantum Reed-Muller Codes

    NASA Astrophysics Data System (ADS)

    Campbell, Earl T.; Anwar, Hussain; Browne, Dan E.

    2012-10-01

    We propose families of protocols for magic-state distillation—important components of fault-tolerance schemes—for systems of odd prime dimension. Our protocols utilize quantum Reed-Muller codes with transversal non-Clifford gates. We find that, in higher dimensions, small and effective codes can be used that have no direct analogue in qubit (two-dimensional) systems. We present several concrete protocols, including schemes for three-dimensional (qutrit) and five-dimensional (ququint) systems. The five-dimensional protocol is, by many measures, the best magic-state-distillation scheme yet discovered. It excels both in terms of error threshold with respect to depolarizing noise (36.3%) and the efficiency measure known as yield, where, for a large region of parameters, it outperforms its qubit counterpart by many orders of magnitude.

  18. Kinetic asymmetry in the gel-liquid crystalline state transitions of DDAB vesicles studied by differential scanning calorimetry.

    PubMed

    Feitosa, Eloi

    2010-04-01

    Didodecyldimethylammonium bromide (DDAB) (1.0 mM) vesicles in water were investigated by differential scanning calorimetry (DSC) to highlight the existing kinetic asymmetry in the gel-liquid crystalline (LC) state transitions. The experiments were performed in the range of temperature, scan rate and pre-scanning time 5-45 degrees C, 15-90 degrees C/h and 0-16 h, respectively, in the up- and down-scanning modes. Depending on the input parameters and number of heating-cooling cycles, the DSC thermograms exhibit a sharp peak, a broad band or a flat shape. A melting temperature T(m)=15.6-16.0 degrees C, given by the peak position, was obtained independently of the scan rate used in the up-scanning mode. The data reveal that DDAB vesicles exhibit much slower kinetics for the LC to gel state than for the opposite transition. Such an asymmetry is supported by: (a) the absence of peak for shorter pre-scanning times but longer scan rates, (b) the increasing intensity of the DSC peak with increasing pre-scanning time and decreasing scan rate, and (c) the complete absence of peak in the down-scan mode. Longer pre-scanning time, however, yields crystal precipitates due to a Krafft phenomenon, which also reduces the peak intensity. The overall results depend on whether the sample is fresh or not, that is, after some heating-cooling cycles, the melting peak requires a longer pre-scanning time to be detected. The kinetic asymmetry explains, for example, the lack of any DSC melting peak reported for "non-fresh" DDAB vesicles, which was as yet unexplained. Copyright 2009 Elsevier Inc. All rights reserved.

  19. Helical vesicles, segmented semivesicles, and noncircular bilayer sheets from solution-state self-assembly of ABC miktoarm star terpolymers.

    PubMed

    Kong, Weixin; Li, Baohui; Jin, Qinghua; Ding, Datong; Shi, An-Chang

    2009-06-24

    Multicompartment micelles, especially nanostructured vesicles, offer tremendous potential as delivery vehicles of therapeutic agents and nanoreactors. Solution-state self-assembly of miktoarm star terpolymers provides a versatile and powerful route to obtain multicompartment micelles. Here we report simulations of solution-state self-assembly of ABC star terpolymers composed of a solvophilic A arm and two solvophobic B and C arms. A variety of multicompartment micelles are predicted from the simulations. Phase diagrams for typical star terpolymers are constructed. It is discovered that the overall micelle morphology is largely controlled by the volume fraction of the solvophilic A arms, whereas the internal compartmented and/or segregated structures depend on the ratio between the volume fractions of the two solvophobic arms. The polymer-solvent and polymer-polymer interactions can be used to tune the effective volume fraction of the A-arm and, thereby, induce morphological transitions. For terpolymers with equal or nearly equal length of B and C arms, several previously unknown structures, including vesicles with novel lateral structures (helices or stacked donuts), segmented semivesicles, and elliptic or triangular bilayer sheets, are discovered. When the lengths of B and C arms are not equal, novel micelles such as multicompartment disks and onions are observed.

  20. Gas vesicles.

    PubMed Central

    Walsby, A E

    1994-01-01

    The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins. Images PMID:8177173

  1. Ground- and excited-state tautomerism in 2-(3{prime}-hydroxy-2{prime}-pyridyl)benzimidazole

    SciTech Connect

    Prieto, F.R.; Rodriguez, M.C.R.; Gonzalez, M.M.; Fernandez, M.A.R.

    1994-09-01

    Ground-state HPyBI is determined to have keto-enol equilibrium in water, and the enol form predominates in nonaqueous solutions. The keto form is the only excited form in all the solvents considered. Ultrafast intramolecular proton transfer creates the enol form from the keto form. 47 refs., 6 figs., 3 tabs.

  2. State-to-state rates for the D + H2(v = 1, j = 1) yield HD(v-prime, j-prime) + H reaction - Predictions and measurements

    NASA Technical Reports Server (NTRS)

    Neuhauser, Daniel; Judson, Richard S.; Kouri, Donald J.; Adelman, David E.; Shafer, Neil E.; Kliner, Dahv A. V.; Zare, Richard N.

    1992-01-01

    A fully quantal wavepacket approach to reactive scattering in which the best available H3 potential energy surface was used enabled a comparison with experimentally determined rates for the D + H2(v = 1, j = 1) yield HD(v-prime = 0, 1, 2; j-prime) + H reaction at significantly higher total energies (1.4 to 2.25 electron volts) than previously possible. The theoretical results are obtained over a sufficient range of conditions that a detailed simulation of the experiment was possible, thus making this a definitive comparison of experiment and theory. Good to excellent agreement is found for the vibrational branching ratios and for the rotational distributions within each product vibrational level. However, the calculated rotational distributions are slightly hotter than the experimentally measured ones.

  3. Disruption of the autoinhibited state primes the E3 ligase parkin for activation and catalysis.

    PubMed

    Kumar, Atul; Aguirre, Jacob D; Condos, Tara E C; Martinez-Torres, R Julio; Chaugule, Viduth K; Toth, Rachel; Sundaramoorthy, Ramasubramanian; Mercier, Pascal; Knebel, Axel; Spratt, Donald E; Barber, Kathryn R; Shaw, Gary S; Walden, Helen

    2015-10-14

    The PARK2 gene is mutated in 50% of autosomal recessive juvenile parkinsonism (ARJP) cases. It encodes parkin, an E3 ubiquitin ligase of the RBR family. Parkin exists in an autoinhibited state that is activated by phosphorylation of its N-terminal ubiquitin-like (Ubl) domain and binding of phosphoubiquitin. We describe the 1.8 Å crystal structure of human parkin in its fully inhibited state and identify the key interfaces to maintain parkin inhibition. We identify the phosphoubiquitin-binding interface, provide a model for the phosphoubiquitin-parkin complex and show how phosphorylation of the Ubl domain primes parkin for optimal phosphoubiquitin binding. Furthermore, we demonstrate that the addition of phosphoubiquitin leads to displacement of the Ubl domain through loss of structure, unveiling a ubiquitin-binding site used by the E2~Ub conjugate, thus leading to active parkin. We find the role of the Ubl domain is to prevent parkin activity in the absence of the phosphorylation signals, and propose a model for parkin inhibition, optimization for phosphoubiquitin recruitment, release of inhibition by the Ubl domain and engagement with an E2~Ub conjugate. Taken together, this model provides a mechanistic framework for activating parkin.

  4. Syllabic pseudohomophone priming in tip-of-the-tongue states resolution: the role of syllabic position and number of syllables.

    PubMed

    Pureza, Rita; Soares, Ana Paula; Comesaña, Montserrat

    2013-01-01

    The tip-of-the-tongue (TOT) state is a common experience, usually coupled with a frustrating feeling caused by the incapability of retrieving a familiar word. It is thought that TOTs occur when the semantic and syntactic information of the word is retrieved but not its phonology. This study aims to further understand the role of phonology in TOT resolution. Specifically, using a syllabic pseudohomophone priming paradigm, we aim to analyse the role of the phonological syllabic position (first vs. last) and the number of syllables in TOT states resolution. TOT was elicited by a picture naming task, after which a lexical decision task was presented. Here, first, last, or none of the phonological syllables of the target word were embedded in pseudohomophone primes. Results showed a significant syllabic pseudohomophone priming effect facilitating TOT resolution. The effect was stronger for four-syllable words, especially when the last syllable was used as prime. These results seem to reinforce the importance of phonology in TOT states resolution, particularly the role of the syllable as an important sublexical unit in speech processing.

  5. Studying calcium triggered vesicle fusion in a single vesicle-vesicle content/lipid mixing system

    PubMed Central

    Kyoung, Minjoung; Zhang, Yunxiang; Diao, Jiajie; Chu, Steven; Brunger, Axel T.

    2013-01-01

    This Protocol describes a single vesicle-vesicle microscopy system to study Ca2+-triggered vesicle fusion. Donor vesicles contain reconstituted synaptobrevin and synaptotagmin-1. Acceptor vesicles contain reconstituted syntaxin and SNAP-25, and are tethered to a PEG-coated glass surface. Donor vesicles are mixed with the tethered acceptor vesicles and incubated for several minutes at zero Ca2+-concentration, resulting in a collection of single interacting vesicle pairs. The donor vesicles also contain two spectrally distinct fluorophores that allow simultaneous monitoring of temporal changes of the content and membrane. Upon Ca2+-injection into the sample chamber, our system therefore differentiates between hemifusion and complete fusion of interacting vesicle pairs and determines the temporal sequence of these events on a sub-hundred millisecond timescale. Other factors, such as complexin, can be easily added. Our system is unique by monitoring both content and lipid mixing, and by starting from a metastable state of interacting vesicle pairs prior to Ca2+-injection. PMID:23222454

  6. Rapid Detection of an ABT-737-Sensitive Primed for Death State in Cells Using Microplate-Based Respirometry

    PubMed Central

    Clerc, Pascaline; Carey, Gregory B.; Mehrabian, Zara; Wei, Michael; Hwang, Hyehyun; Girnun, Geoffrey D.; Chen, Hegang; Martin, Stuart S.; Polster, Brian M.

    2012-01-01

    Cells that exhibit an absolute dependence on the anti-apoptotic BCL-2 protein for survival are termed “primed for death” and are killed by the BCL-2 antagonist ABT-737. Many cancers exhibit a primed phenotype, including some that are resistant to conventional chemotherapy due to high BCL-2 expression. We show here that 1) stable BCL-2 overexpression alone can induce a primed for death state and 2) that an ABT-737-induced loss of functional cytochrome c from the electron transport chain causes a reduction in maximal respiration that is readily detectable by microplate-based respirometry. Stable BCL-2 overexpression sensitized non-tumorigenic MCF10A mammary epithelial cells to ABT-737-induced caspase-dependent apoptosis. Mitochondria within permeabilized BCL-2 overexpressing cells were selectively vulnerable to ABT-737-induced cytochrome c release compared to those from control-transfected cells, consistent with a primed state. ABT-737 treatment caused a dose-dependent impairment of maximal O2 consumption in MCF10A BCL-2 overexpressing cells but not in control-transfected cells or in immortalized mouse embryonic fibroblasts lacking both BAX and BAK. This impairment was rescued by delivering exogenous cytochrome c to mitochondria via saponin-mediated plasma membrane permeabilization. An ABT-737-induced reduction in maximal O2 consumption was also detectable in SP53, JeKo-1, and WEHI-231 B-cell lymphoma cell lines, with sensitivity correlating with BCL-2:MCL-1 ratio and with susceptibility (SP53 and JeKo-1) or resistance (WEHI-231) to ABT-737-induced apoptosis. Multiplexing respirometry assays to ELISA-based determination of cytochrome c redistribution confirmed that respiratory inhibition was associated with cytochrome c release. In summary, cell-based respiration assays were able to rapidly identify a primed for death state in cells with either artificially overexpressed or high endogenous BCL-2. Rapid detection of a primed for death state in individual cancers

  7. Rapid detection of an ABT-737-sensitive primed for death state in cells using microplate-based respirometry.

    PubMed

    Clerc, Pascaline; Carey, Gregory B; Mehrabian, Zara; Wei, Michael; Hwang, Hyehyun; Girnun, Geoffrey D; Chen, Hegang; Martin, Stuart S; Polster, Brian M

    2012-01-01

    Cells that exhibit an absolute dependence on the anti-apoptotic BCL-2 protein for survival are termed "primed for death" and are killed by the BCL-2 antagonist ABT-737. Many cancers exhibit a primed phenotype, including some that are resistant to conventional chemotherapy due to high BCL-2 expression. We show here that 1) stable BCL-2 overexpression alone can induce a primed for death state and 2) that an ABT-737-induced loss of functional cytochrome c from the electron transport chain causes a reduction in maximal respiration that is readily detectable by microplate-based respirometry. Stable BCL-2 overexpression sensitized non-tumorigenic MCF10A mammary epithelial cells to ABT-737-induced caspase-dependent apoptosis. Mitochondria within permeabilized BCL-2 overexpressing cells were selectively vulnerable to ABT-737-induced cytochrome c release compared to those from control-transfected cells, consistent with a primed state. ABT-737 treatment caused a dose-dependent impairment of maximal O(2) consumption in MCF10A BCL-2 overexpressing cells but not in control-transfected cells or in immortalized mouse embryonic fibroblasts lacking both BAX and BAK. This impairment was rescued by delivering exogenous cytochrome c to mitochondria via saponin-mediated plasma membrane permeabilization. An ABT-737-induced reduction in maximal O(2) consumption was also detectable in SP53, JeKo-1, and WEHI-231 B-cell lymphoma cell lines, with sensitivity correlating with BCL-2:MCL-1 ratio and with susceptibility (SP53 and JeKo-1) or resistance (WEHI-231) to ABT-737-induced apoptosis. Multiplexing respirometry assays to ELISA-based determination of cytochrome c redistribution confirmed that respiratory inhibition was associated with cytochrome c release. In summary, cell-based respiration assays were able to rapidly identify a primed for death state in cells with either artificially overexpressed or high endogenous BCL-2. Rapid detection of a primed for death state in individual cancers

  8. Word encoding during sleep is suggested by correlations between word-evoked up-states and post-sleep semantic priming.

    PubMed

    Ruch, Simon; Koenig, Thomas; Mathis, Johannes; Roth, Corinne; Henke, Katharina

    2014-01-01

    To test whether humans can encode words during sleep we played everyday words to men while they were napping and assessed priming from sleep-played words following waking. Words were presented during non-rapid eye movement (NREM) sleep. Priming was assessed using a semantic and a perceptual priming test. These tests measured differences in the processing of words that had been or had not been played during sleep. Synonyms to sleep-played words were the targets in the semantic priming test that tapped the meaning of sleep-played words. All men responded to sleep-played words by producing up-states in their electroencephalogram. Up-states are NREM sleep-specific phases of briefly increased neuronal excitability. The word-evoked up-states might have promoted word processing during sleep. Yet, the mean performance in the priming tests administered following sleep was at chance level, which suggests that participants as a group failed to show priming following sleep. However, performance in the two priming tests was positively correlated to each other and to the magnitude of the word-evoked up-states. Hence, the larger a participant's word-evoked up-states, the larger his perceptual and semantic priming. Those participants who scored high on all variables must have encoded words during sleep. We conclude that some humans are able to encode words during sleep, but more research is needed to pin down the factors that modulate this ability.

  9. Word encoding during sleep is suggested by correlations between word-evoked up-states and post-sleep semantic priming

    PubMed Central

    Ruch, Simon; Koenig, Thomas; Mathis, Johannes; Roth, Corinne; Henke, Katharina

    2014-01-01

    To test whether humans can encode words during sleep we played everyday words to men while they were napping and assessed priming from sleep-played words following waking. Words were presented during non-rapid eye movement (NREM) sleep. Priming was assessed using a semantic and a perceptual priming test. These tests measured differences in the processing of words that had been or had not been played during sleep. Synonyms to sleep-played words were the targets in the semantic priming test that tapped the meaning of sleep-played words. All men responded to sleep-played words by producing up-states in their electroencephalogram. Up-states are NREM sleep-specific phases of briefly increased neuronal excitability. The word-evoked up-states might have promoted word processing during sleep. Yet, the mean performance in the priming tests administered following sleep was at chance level, which suggests that participants as a group failed to show priming following sleep. However, performance in the two priming tests was positively correlated to each other and to the magnitude of the word-evoked up-states. Hence, the larger a participant's word-evoked up-states, the larger his perceptual and semantic priming. Those participants who scored high on all variables must have encoded words during sleep. We conclude that some humans are able to encode words during sleep, but more research is needed to pin down the factors that modulate this ability. PMID:25452740

  10. Fusion competent synaptic vesicles persist upon active zone disruption and loss of vesicle docking

    PubMed Central

    Wang, Shan Shan H.; Held, Richard G.; Wong, Man Yan; Liu, Changliang; Karakhanyan, Aziz; Kaeser, Pascal S.

    2016-01-01

    In a nerve terminal, synaptic vesicle docking and release are restricted to an active zone. The active zone is a protein scaffold that is attached to the presynaptic plasma membrane and opposed to postsynaptic receptors. Here, we generated conditional knockout mice removing the active zone proteins RIM and ELKS, which additionally led to loss of Munc13, Bassoon, Piccolo, and RIM-BP, indicating disassembly of the active zone. We observed a near complete lack of synaptic vesicle docking and a strong reduction in vesicular release probability and the speed of exocytosis, but total vesicle numbers, SNARE protein levels, and postsynaptic densities remained unaffected. Despite loss of the priming proteins Munc13 and RIM and of docked vesicles, a pool of releasable vesicles remained. Thus, the active zone is necessary for synaptic vesicle docking and to enhance release probability, but releasable vesicles can be localized distant from the presynaptic plasma membrane. PMID:27537483

  11. CAPS1 stabilizes the state of readily releasable synaptic vesicles to fusion competence at CA3–CA1 synapses in adult hippocampus

    PubMed Central

    Shinoda, Yo; Ishii, Chiaki; Fukazawa, Yugo; Sadakata, Tetsushi; Ishii, Yuki; Sano, Yoshitake; Iwasato, Takuji; Itohara, Shigeyoshi; Furuichi, Teiichi

    2016-01-01

    Calcium-dependent activator protein for secretion 1 (CAPS1) regulates exocytosis of dense-core vesicles in neuroendocrine cells and of synaptic vesicles in neurons. However, the synaptic function of CAPS1 in the mature brain is unclear because Caps1 knockout (KO) results in neonatal death. Here, using forebrain-specific Caps1 conditional KO (cKO) mice, we demonstrate, for the first time, a critical role of CAPS1 in adult synapses. The amplitude of synaptic transmission at CA3–CA1 synapses was strongly reduced, and paired-pulse facilitation was significantly increased, in acute hippocampal slices from cKO mice compared with control mice, suggesting a perturbation in presynaptic function. Morphological analysis revealed an accumulation of synaptic vesicles in the presynapse without any overall morphological change. Interestingly, however, the percentage of docked vesicles was markedly decreased in the Caps1 cKO. Taken together, our findings suggest that CAPS1 stabilizes the state of readily releasable synaptic vesicles, thereby enhancing neurotransmitter release at hippocampal synapses. PMID:27545744

  12. Cell-Type-Specific Chromatin States Differentially Prime Squamous Cell Carcinoma Tumor-Initiating Cells for Epithelial to Mesenchymal Transition.

    PubMed

    Latil, Mathilde; Nassar, Dany; Beck, Benjamin; Boumahdi, Soufiane; Wang, Li; Brisebarre, Audrey; Dubois, Christine; Nkusi, Erwin; Lenglez, Sandrine; Checinska, Agnieszka; Vercauteren Drubbel, Alizée; Devos, Michael; Declercq, Wim; Yi, Rui; Blanpain, Cédric

    2017-02-02

    Epithelial to mesenchymal transition (EMT) in cancer cells has been associated with metastasis, stemness, and resistance to therapy. Some tumors undergo EMT while others do not, which may reflect intrinsic properties of their cell of origin. However, this possibility is largely unexplored. By targeting the same oncogenic mutations to discrete skin compartments, we show that cell-type-specific chromatin and transcriptional states differentially prime tumors to EMT. Squamous cell carcinomas (SCCs) derived from interfollicular epidermis (IFE) are generally well differentiated, while hair follicle (HF) stem cell-derived SCCs frequently exhibit EMT, efficiently form secondary tumors, and possess increased metastatic potential. Transcriptional and epigenomic profiling revealed that IFE and HF tumor-initiating cells possess distinct chromatin landscapes and gene regulatory networks associated with tumorigenesis and EMT that correlate with accessibility of key epithelial and EMT transcription factor binding sites. These findings highlight the importance of chromatin states and transcriptional priming in dictating tumor phenotypes and EMT.

  13. How state counter-industry campaigns help prime perceptions of tobacco industry practices to promote reductions in youth smoking

    PubMed Central

    Hersey, J; Niederdeppe, J; Ng, S; Mowery, P; Farrelly, M; Messeri, P

    2005-01-01

    Methods: Rates of youth smoking were compared in three groups of states: (1) those with long funded counter-industry campaigns (California, Florida, and Massachusetts); (2) states with more recently funded counter-industry media campaigns (Indiana, Minnesota, Mississippi, and New Jersey); and (3) other states. An analysis was performed for a series of national telephone surveys of 12–17 year olds between 1999 and 2002, controlling for differences in demographic background, the price of cigarettes, and exposure to the national truth® campaign. Results: Between 1999 and 2002, rates of current smoking and established smoking decreased significantly faster in states with established or more newly funded counter-industry campaigns than in other states. State counter-industry campaigns appear to prime, or make more salient, negative perceptions about tobacco industry practices. Conclusion: Results highlight the value of continued state counter-industry campaigns. PMID:16319360

  14. Double resonance spectroscopy of the D {}^1 \\Pi _u^+ and B^{\\prime \\prime }\\barB^1\\Sigma ^+_u states near the third dissociation threshold of H2

    NASA Astrophysics Data System (ADS)

    Ekey, R. C.; Cordova, A. E.; Duan, W.; Chartrand, A. M.; McCormack, E. F.

    2013-12-01

    Double-resonance laser spectroscopy via the E,F {}^1 \\Sigma _g^+, v^{\\prime }=6, J^{\\prime } state was used to probe the energy region below the third dissociation limit of molecular hydrogen. Resonantly enhanced multi-photon ionization spectra were recorded by detecting ion production as a function of energy using a time-of-flight mass spectrometer. Energies and line widths for the v = 14-17 levels of the D{}^1 \\Pi _u^+ state of H2 are reported and compared to experimental data obtained by using VUV synchrotron light excitation (Dickenson et al 2010 J. Chem. Phys. 133 144317) and fully ab initio non-adiabatic calculations of D {}^1 \\Pi _u^+ state energies and line widths (Glass-Maujean et al 2012 Phys. Rev. A 86 052507). Several high vibrational levels of the B^{\\prime \\prime }\\bar{B}^1\\Sigma ^+_u state were also observed in this region. Term energies and rotational constants for the v = 67-69 vibrational levels are reported and compared to highly accurate ro-vibrational energy level predictions from fully ab initio non-adiabatic calculations of the first six {}^1 \\Sigma _u^+ levels of H2 (Wolniewicz et al 2006 J. Mol. Spectrosc. 238 118). While additional observed transitions can be assigned to other states, several unassigned features in the spectra highlight the need for a fully integrated theoretical treatment of dissociation and ionization to understand the complex pattern of highly vibrationally excited states expected in this region.

  15. Dollar Summary of Prime Contract Awards by Contractor, State or Country, and Place, FY84, Part 6, (Magnasync/Moviola Corp-Parker Marine Contracting).

    DTIC Science & Technology

    1984-01-01

    11111220 11111_L 5 . 1161 ]lllI ’° lh Ŝ MICROCOPY RESOLUTION TESI CHART N10iANAL hR111 I~ A S-7 DOLLAR SUMMARY OF PRIME CONTRACT AWARDS BY...CONTRACTOR, STATE OR COUNTRY, AND PLACE PART 6 AD-A151 648 FISCAL YEAR 1984 JcLI II - , TID MPC91,5 DOG PRIME CONTRACT AWARDS OVCR h𔃿,000 BY CONTRACTOR, STATE

  16. The low-energy, charge-transfer excited states of 4-amino-4-prime-nitrodiphenyl sulfide

    NASA Technical Reports Server (NTRS)

    O'Connor, Donald B.; Scott, Gary W.; Tran, Kim; Coulter, Daniel R.; Miskowski, Vincent M.; Stiegman, Albert E.; Wnek, Gary E.

    1992-01-01

    Absorption and emission spectra of 4-amino-4-prime-nitrodiphenyl sulfide in polar and nonpolar solvents were used to characterize and assign the low-energy excited states of the molecule. Fluorescence-excitation anisotropy spectra and fluorescence quantum yields were also used to characterize the photophysics of these states. The lowest-energy fluorescent singlet state was determined to be an intramolecular charge transfer (ICT) state involving transfer of a full electron charge from the amino to the nitro group yielding a dipole moment of about 50 D. A low-energy, intense absorption band is assigned as a transition to a different ICT state involving a partial electron charge transfer from sulfur to the nitro group.

  17. O-GlcNAc is required for the survival of primed pluripotent stem cells and their reversion to the naïve state.

    PubMed

    Miura, Taichi; Nishihara, Shoko

    2016-10-27

    "Naïve" mouse embryonic stem cells (ESCs) are derived from pre-implantation embryos and possess pluripotency, the ability to differentiate into any cell type of the body. "Primed" mouse epiblast stem cells (EpiSCs) are also pluripotent but are derived from post-implantation embryos. ESC-derived EpiSCs (ESD-EpiSCs) are "primed" pluripotent stem cells and can revert to naïve reverted ESCs (rESCs). O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) is a posttranslational modification in the cytoplasm and nucleus. O-GlcNAc is transferred to serine and threonine residues of proteins by O-GlcNAc transferase (Ogt) and removed from them by O-GlcNAcase (Oga). In naïve ESCs, O-GlcNAc contributes to maintain the undifferentiated state. In the transition from naïve state to primed state, Ogt maintains cell survival, whereas Oga has no function. However, the function of O-GlcNAc in primed ESD-EpiSCs and during the reversion from the primed state to naïve rESCs remains unclear. Here, we show that Ogt is required for the survival of primed ESD-EpiSCs. The expression of cytosolic Oga was significantly increased during induction from naïve ESCs to primed ESD-EpiSCs. Furthermore, both Ogt and Oga were required for the reversion from primed ESD-EpiSCs to naïve rESCs. These findings indicate that O-GlcNAcylation plays an important role in the survival of primed ESD-EpiSCs and in their reversion to naïve rESCs.

  18. Additive effects on the energy barrier for synaptic vesicle fusion cause supralinear effects on the vesicle fusion rate

    PubMed Central

    Schotten, Sebastiaan; Meijer, Marieke; Walter, Alexander Matthias; Huson, Vincent; Mamer, Lauren; Kalogreades, Lawrence; ter Veer, Mirelle; Ruiter, Marvin; Brose, Nils; Rosenmund, Christian

    2015-01-01

    The energy required to fuse synaptic vesicles with the plasma membrane (‘activation energy’) is considered a major determinant in synaptic efficacy. From reaction rate theory, we predict that a class of modulations exists, which utilize linear modulation of the energy barrier for fusion to achieve supralinear effects on the fusion rate. To test this prediction experimentally, we developed a method to assess the number of releasable vesicles, rate constants for vesicle priming, unpriming, and fusion, and the activation energy for fusion by fitting a vesicle state model to synaptic responses induced by hypertonic solutions. We show that complexinI/II deficiency or phorbol ester stimulation indeed affects responses to hypertonic solution in a supralinear manner. An additive vs multiplicative relationship between activation energy and fusion rate provides a novel explanation for previously observed non-linear effects of genetic/pharmacological perturbations on synaptic transmission and a novel interpretation of the cooperative nature of Ca2+-dependent release. DOI: http://dx.doi.org/10.7554/eLife.05531.001 PMID:25871846

  19. The transition from naïve to primed nociceptive state: A novel wind-up protocol in mice.

    PubMed

    Ziv, Nadav Y; Tal, Michael; Shavit, Yehuda

    2016-01-01

    Wind-up (WU) is a progressive, frequency-dependent facilitation of spinal cord neurons in response to repetitive nociceptive stimulation of constant intensity. We identified a new WU-associated phenomenon in naïve mice (not exposed to noxious stimulation immediately prior to WU stimulation), which were subjected to a novel experimental protocol composed of three consecutive trains of WU stimulation. The 1st train produced a typical linear 'wind-up' curve as expected following a repeating series of stimuli; in addition, this 1st train sensitized ('primed') the nociceptive system so that the responses to two subsequent trains (inter-train interval of 10 min) were significantly amplified compared with the response to the 1st train. We named this augmented response potentiation-of-windup, or "PoW". The PoW phenomenon appears to be centrally mediated, as the augmented response was suppressed by administration of an NMDA receptor antagonist (MK-801) and by cutting the spinal cord. Furthermore, the PoW protocol is accompanied by enhanced pain behavior. The 'priming' effect of the 1st train could be mimicked by exposure to natural noxious stimuli prior to the PoW protocol. Presumably, the PoW phenomenon has not been previously reported due to a procedural reason: typically, WU protocols have been executed in 'primed' rather than naïve animals, i.e., animals exposed to nociceptive stimulation prior to the actual WU recording. Our findings indicate that the PoW paradigm can distinguish between 'naïve' and 'primed' states, suggesting its use as a tool for the assessment of central sensitization.

  20. Photoexcited states of biruthenium(II) compounds bridged by 2,2 prime -bis(2-pyridyl)bibenzimidazole or 1,2-bis(2-(2-pyridyl)benzimidazolyl)ethane

    SciTech Connect

    Ohno, Takeshi; Nozaki, Koichi ); Haga, Masaaki )

    1992-02-19

    Charge-transfer (CT) excited states of RuL{sub 2}(L{prime}-L{prime}){sup 2+} and RuL{sub 2}(L{prime}-L{prime}){sup 4+} have been studied by means of emission and transient absorption (TA) spectroscopy at 77-300 K. The bridging ligand (L{prime}-L{prime}) is either 2,2{prime}-bis(2-pyridyl)benzimidazole (bpbimH{sub 2}) or 1,2-bis(2-(2-pyridyl)benzimidazolyl)ethane (dpbime) and L is 2,2{prime}-bipyridine (bpy), 4,4{prime}-dimethyl-2,2{prime}-bipyridine (dmbpy), or 1,10-phenanthroline (phen). Transient absorption (TA) spectra of the ruthenium(II) compounds subjected to laser excitation, whose molar extinction coefficients were determined, are deconvoluted to {pi}-{pi}* bands of L and L{prime}-L{prime} coordinating to Ru(III), L (or L{prime}-L{prime})-to-Ru(III) CT bands, and a {pi}-{pi}* band of (L{prime}-L{prime}){sup {center dot}-} (or L{sup {center dot}-}) by comparison with the absorption spectra of the oxidized compounds (RuL{sub 2}(L{prime}-L{prime}){sup 3+}). The degree of electron population on the ligand decreases in the order bpbimH{sub 2} > bpy {approximately} phen > dpbime > dmbpy in the excited CT states, while there is no discernible difference in the reduction potential between bpbimH{sub 2} (or dpbime) and bpy coordinating to Ru(II). The excitation efficiency of the metal sites in (Ru(bpy){sub 2}){sub 2}(dpbime){sup 4+} is lower than 50% when the laser power was large enough to excite more than 80% of the mononuclear compounds. The low excitation efficiency of the former is ascribed to rapid intramolecular annihilation of the excited states.

  1. Comparative FAIRE-seq analysis reveals distinguishing features of the chromatin structure of ground state- and primed-pluripotent cells.

    PubMed

    Murtha, Matthew; Strino, Francesco; Tokcaer-Keskin, Zeynep; Sumru Bayin, N; Shalabi, Doaa; Xi, Xiangmei; Kluger, Yuval; Dailey, Lisa

    2015-02-01

    Both pluripotent embryonic stem cells (ESCs), established from preimplantation murine blastocysts, and epiblast stem cells (EpiSCs), established from postimplantation embryos, can self-renew in culture or differentiate into each of the primary germ layers. While the core transcription factors (TFs) OCT4, SOX2, and NANOG are expressed in both cell types, the gene expression profiles and other features suggest that ESCs and EpiSCs reflect distinct developmental maturation stages of the epiblast in vivo. Accordingly, "naïve" or "ground state" ESCs resemble cells of the inner cell mass, whereas "primed" EpiSCs resemble cells of the postimplantation egg cylinder. To gain insight into the relationship between naïve and primed pluripotent cells, and of each of these pluripotent states to that of nonpluripotent cells, we have used FAIRE-seq to generate a comparative atlas of the accessible chromatin regions within ESCs, EpiSCs, multipotent neural stem cells, and mouse embryonic fibroblasts. We find a distinction between the accessible chromatin patterns of pluripotent and somatic cells that is consistent with the highly related phenotype of ESCs and EpiSCs. However, by defining cell-specific and shared regions of open chromatin, and integrating these data with published gene expression and ChIP analyses, we also illustrate unique features of the chromatin of naïve and primed cells. Functional studies suggest that multiple stage-specific enhancers regulate ESC- or EpiSC-specific gene expression, and implicate auxiliary TFs as important modulators for stage-specific activation by the core TFs. Together these observations provide insights into the chromatin structure dynamics accompanying transitions between these pluripotent states. © 2014 AlphaMed Press.

  2. Modeling of decomposition activity and priming effect in soil using the versatile index of microbial physiological state

    NASA Astrophysics Data System (ADS)

    Blagodatskiy, Sergey

    2015-04-01

    The implementation of microbial biomass in soil organic matter (SOM) models is still unresolved issue. The approaches using explicit description of microbial biomass (decomposer) interaction with SOM usually cannot be easily verified by means of experimental estimating of total microbial biomass dynamics. Standard experimental methods, such as fumigation extraction or direct microscopic count, does not represent microbial activity (Blagodatskaya and Kuzyakov, 2013), which is essential for the control of decomposition rate. More advanced approaches, explicitly simulating intracellular metabolic activity (Resat et al., 2012) and e.g. production and turnover of extracellular enzymes (Lawrence et al., 2009) are prohibitively complex for the field and larger scales, which are most often under demand for SOM modelling. One possible parsimonious solution is an application of index of microbial physiological state (r), which describes the adaptive variation of the cell composition and metabolic activity by one variable (Panikov, 1995). This variable (r) can reflect the microbial response to the availability of carbon and nitrogen and shift of microbial biomass between active and dormant state (Blagodatsky and Richter, 1998), but also can be used for the description of the effect of external factors, such as temperature and moisture, on microbial activity. This approach is extremely useful for the description of priming effect (Blagodatsky et al., 2010) and the influence of substrate availability and external factors on the size and dynamics of priming. Distinguishing of these two types of driving forces for priming is crucial for modelling of SOM dynamics and steady-state stocks of different SOM pools. I will present the analysis of model response on combination of limiting factors presented as functions controlling the change of microbial physiological state and size of priming effect. Alternatively, the direct effect of the same factors on decomposition rate and priming

  3. Medium-resolution studies of extreme ultraviolet emission from N2 by electron impact - Vibrational perturbations and cross sections of the c4-prime 1Sigma(+)u and b-prime 1Sigma(+)u states

    NASA Technical Reports Server (NTRS)

    Ajello, Joseph M.; James, Geoffrey K.; Franklin, Brian O.; Shemansky, Donald E.

    1989-01-01

    In a crossed-beam experiment the electron-impact-induced fluorescence spectrum of N2 in the extreme ultraviolet is studied at a spectral resolution of up to 0.03 nm. The optically thin experiment obtained the highest-resolution electron-impact emission spectrum of the Rydberg and valence states of N2. The spectral measurements provide the emission cross sections of each of the vibrational transitions of the Carroll-Yoshino and the Birge-Hopfield-II band systems. Laboratory vibrational-excitation cross sections arising from the mutual perturbation of the c4-prime 1Sigma(+)u and b-prime 1Sigma(+)u states by homogeneous configuration interactions are measured from 10 to 400 eV, and a modified Born approximation analytic model is given for them. The analysis leads to accurate band-system oscillator strengths. The relative emission and excitation cross sections each of the vibrational levels are compared. In addition, low-resolution measurements of the cross section of the atomic dissociation fragments (NI, NII, NIII) from 40 to 102 nm are made, and medium-resolution measurements are made of the emission cross section of the c4 1Pi(u), c5-prime 1Sigma(+)u, c5 1Pi(u), and c6-prime 1Sigma(+)u to X 1Sigma(+)g (0,0) transitions.

  4. Reconstitution of calcium-mediated exocytosis of dense-core vesicles

    PubMed Central

    Kreutzberger, Alex J. B.; Kiessling, Volker; Liang, Binyong; Seelheim, Patrick; Jakhanwal, Shrutee; Jahn, Reinhard; Castle, J. David; Tamm, Lukas K.

    2017-01-01

    Regulated exocytosis is a process by which neurotransmitters, hormones, and secretory proteins are released from the cell in response to elevated levels of calcium. In cells, secretory vesicles are targeted to the plasma membrane, where they dock, undergo priming, and then fuse with the plasma membrane in response to calcium. The specific roles of essential proteins and how calcium regulates progression through these sequential steps are currently incompletely resolved. We have used purified neuroendocrine dense-core vesicles and artificial membranes to reconstruct in vitro the serial events that mimic SNARE (soluble N-ethylmaleimide–sensitive factor attachment protein receptor)–dependent membrane docking and fusion during exocytosis. Calcium recruits these vesicles to the target membrane aided by the protein CAPS (calcium-dependent activator protein for secretion), whereas synaptotagmin catalyzes calcium-dependent fusion; both processes are dependent on phosphatidylinositol 4,5-bisphosphate. The soluble proteins Munc18 and complexin-1 are necessary to arrest vesicles in a docked state in the absence of calcium, whereas CAPS and/or Munc13 are involved in priming the system for an efficient fusion reaction. PMID:28776026

  5. Kinetic barriers to SNAREpin assembly in the regulation of membrane docking/priming and fusion

    PubMed Central

    Li, Feng; Tiwari, Neeraj; Rothman, James E.; Pincet, Frederic

    2016-01-01

    Neurotransmission is achieved by soluble NSF attachment protein receptor (SNARE)-driven fusion of readily releasable vesicles that are docked and primed at the presynaptic plasma membrane. After neurotransmission, the readily releasable pool of vesicles must be refilled in less than 100 ms for subsequent release. Here we show that the initial association of SNARE complexes, SNAREpins, is far too slow to support this rapid refilling owing to an inherently high activation energy barrier. Our data suggest that acceleration of this process, i.e., lowering of the barrier, is physiologically necessary and can be achieved by molecular factors. Furthermore, under zero force, a low second energy barrier transiently traps SNAREpins in a half-zippered state similar to the partial assembly that engages calcium-sensitive regulatory machinery. This result suggests that the barrier must be actively raised in vivo to generate a sufficient pause in the zippering process for the regulators to set in place. We show that the heights of the activation energy barriers can be selectively changed by molecular factors. Thus, it is possible to modify, both in vitro and in vivo, the lifespan of each metastable state. This controllability provides a simple model in which vesicle docking/priming, an intrinsically slow process, can be substantially accelerated. It also explains how the machinery that regulates vesicle fusion can be set in place while SNAREpins are trapped in a half-zippered state. PMID:27601655

  6. Kinetic barriers to SNAREpin assembly in the regulation of membrane docking/priming and fusion.

    PubMed

    Li, Feng; Tiwari, Neeraj; Rothman, James E; Pincet, Frederic

    2016-09-20

    Neurotransmission is achieved by soluble NSF attachment protein receptor (SNARE)-driven fusion of readily releasable vesicles that are docked and primed at the presynaptic plasma membrane. After neurotransmission, the readily releasable pool of vesicles must be refilled in less than 100 ms for subsequent release. Here we show that the initial association of SNARE complexes, SNAREpins, is far too slow to support this rapid refilling owing to an inherently high activation energy barrier. Our data suggest that acceleration of this process, i.e., lowering of the barrier, is physiologically necessary and can be achieved by molecular factors. Furthermore, under zero force, a low second energy barrier transiently traps SNAREpins in a half-zippered state similar to the partial assembly that engages calcium-sensitive regulatory machinery. This result suggests that the barrier must be actively raised in vivo to generate a sufficient pause in the zippering process for the regulators to set in place. We show that the heights of the activation energy barriers can be selectively changed by molecular factors. Thus, it is possible to modify, both in vitro and in vivo, the lifespan of each metastable state. This controllability provides a simple model in which vesicle docking/priming, an intrinsically slow process, can be substantially accelerated. It also explains how the machinery that regulates vesicle fusion can be set in place while SNAREpins are trapped in a half-zippered state.

  7. Analysis of the Source Physics Experiment SPE4 Prime Using State-Of Parallel Numerical Tools.

    NASA Astrophysics Data System (ADS)

    Vorobiev, O.; Ezzedine, S. M.; Antoun, T.; Glenn, L.

    2015-12-01

    This work describes a methodology used for large scale modeling of wave propagation from underground chemical explosions conducted at the Nevada National Security Site (NNSS) fractured granitic rock. We show that the discrete natures of rock masses as well as the spatial variability of the fabric of rock properties are very important to understand ground motions induced by underground explosions. In order to build a credible conceptual model of the subsurface we integrated the geological, geomechanical and geophysical characterizations conducted during recent test at the NNSS as well as historical data from the characterization during the underground nuclear test conducted at the NNSS. Because detailed site characterization is limited, expensive and, in some instances, impossible we have numerically investigated the effects of the characterization gaps on the overall response of the system. We performed several computational studies to identify the key important geologic features specific to fractured media mainly the joints characterized at the NNSS. We have also explored common key features to both geological environments such as saturation and topography and assess which characteristics affect the most the ground motion in the near-field and in the far-field. Stochastic representation of these features based on the field characterizations has been implemented into LLNL's Geodyn-L hydrocode. Simulations were used to guide site characterization efforts in order to provide the essential data to the modeling community. We validate our computational results by comparing the measured and computed ground motion at various ranges for the recently executed SPE4 prime experiment. We have also conducted a comparative study between SPE4 prime and previous experiments SPE1 and SPE3 to assess similarities and differences and draw conclusions on designing SPE5.

  8. Poking Vesicles

    NASA Astrophysics Data System (ADS)

    Powers, Thomas R.; Huber, Greg; Goldstein, Raymond E.

    2000-03-01

    Lipid vesicles can exhibit a variety of interesting shapes when subject to point forcing, as has been demonstrated with laser-tweezed beads and with growing microtubules. Using numerical and analytic techniques, we study the force vs. extension in two regimes. At low forces, the resistance to deformation is primarily entropic, with a tension given by the fluctuating bending modes. At high forces, the thermal wrinkles are smoothed out, and there is bending and stretching which balance in a thin tether, which we treat using boundary-layer techniques. This work was supported in part by the Harvard MRSEC and Army Research Office Grant DAA655-97-1-014 (TRP) and NSF DMR9812526 (GH & REG).

  9. Repetition priming influences distinct brain systems: evidence from task-evoked data and resting-state correlations.

    PubMed

    Wig, Gagan S; Buckner, Randy L; Schacter, Daniel L

    2009-05-01

    Behavioral dissociations suggest that a single experience can separately influence multiple processing components. Here we used a repetition priming functional magnetic resonance imaging paradigm that directly contrasted the effects of stimulus and decision changes to identify the underlying brain systems. Direct repetition of stimulus features caused marked reductions in posterior regions of the inferior temporal lobe that were insensitive to whether the decision was held constant or changed between study and test. By contrast, prefrontal cortex showed repetition effects that were sensitive to the exact stimulus-to-decision mapping. Analysis of resting-state functional connectivity revealed that the dissociated repetition effects are embedded within distinct brain systems. Regions that were sensitive to changes in the stimulus correlated with perceptual cortices, whereas the decision changes attenuated activity in regions correlated with middle-temporal regions and a frontoparietal control system. These results thus explain the long-known dissociation between perceptual and conceptual components of priming by revealing how a single experience can separately influence distinct, concurrently active brain systems.

  10. Synaptic Vesicle Proteins and Active Zone Plasticity

    PubMed Central

    Kittel, Robert J.; Heckmann, Manfred

    2016-01-01

    Neurotransmitter is released from synaptic vesicles at the highly specialized presynaptic active zone (AZ). The complex molecular architecture of AZs mediates the speed, precision and plasticity of synaptic transmission. Importantly, structural and functional properties of AZs vary significantly, even for a given connection. Thus, there appear to be distinct AZ states, which fundamentally influence neuronal communication by controlling the positioning and release of synaptic vesicles. Vice versa, recent evidence has revealed that synaptic vesicle components also modulate organizational states of the AZ. The protein-rich cytomatrix at the active zone (CAZ) provides a structural platform for molecular interactions guiding vesicle exocytosis. Studies in Drosophila have now demonstrated that the vesicle proteins Synaptotagmin-1 (Syt1) and Rab3 also regulate glutamate release by shaping differentiation of the CAZ ultrastructure. We review these unexpected findings and discuss mechanistic interpretations of the reciprocal relationship between synaptic vesicles and AZ states, which has heretofore received little attention. PMID:27148040

  11. Open Syntaxin Docks Synaptic Vesicles

    PubMed Central

    Olsen, Shawn; Jorgensen, Erik M

    2007-01-01

    Synaptic vesicles dock to the plasma membrane at synapses to facilitate rapid exocytosis. Docking was originally proposed to require the soluble N-ethylmaleimide–sensitive fusion attachment protein receptor (SNARE) proteins; however, perturbation studies suggested that docking was independent of the SNARE proteins. We now find that the SNARE protein syntaxin is required for docking of all vesicles at synapses in the nematode Caenorhabditis elegans. The active zone protein UNC-13, which interacts with syntaxin, is also required for docking in the active zone. The docking defects in unc-13 mutants can be fully rescued by overexpressing a constitutively open form of syntaxin, but not by wild-type syntaxin. These experiments support a model for docking in which UNC-13 converts syntaxin from the closed to the open state, and open syntaxin acts directly in docking vesicles to the plasma membrane. These data provide a molecular basis for synaptic vesicle docking. PMID:17645391

  12. All Prime Contract Awards by State or Country, Place, and Contractor, FY 85. Part 11 (Aitkin, Minnesota - Wilton, New Hampshire).

    DTIC Science & Technology

    1985-01-01

    0 0- 000(0(0(0 (0- 140 4 1 (0 m n *~ II( -41- (0 Nc (000)00( (00-(0 C’) m anLA enOx (0 m I(0 - 01z(0 0C’ (0 000 -m m n cr)cn ) L Xn 0) Im-r0-4C( 04 M 1 ...AD-RI65 165 ALL PRIME CONTRACT AWdARDS BY STATE OR COUNTRY PLACE AND 1 /5 CONTRACTOR FY 85, (U) USSHINGTON HEADQUARTERS SERVICES I (DOD) DC... 1 - IOR,t ’P" 1 - r_/ P- 11 ba NAME OF PERFORMING ORGANIZATION 6b OFFICE SYMBOL 7a. NAME OF MONITORING ORGiANIZATION "S, l’irectorate for Informati n

  13. N-cadherin expression level distinguishes reserved versus primed states of hematopoietic stem cells.

    PubMed

    Haug, Jeffrey S; He, Xi C; Grindley, Justin C; Wunderlich, Joshua P; Gaudenz, Karin; Ross, Jason T; Paulson, Ariel; Wagner, Kathryn P; Xie, Yucai; Zhu, Ruihong; Yin, Tong; Perry, John M; Hembree, Mark J; Redenbaugh, Erin P; Radice, Glenn L; Seidel, Christopher; Li, Linheng

    2008-04-10

    Osteoblasts expressing the homophilic adhesion molecule N-cadherin form a hematopoietic stem cell (HSC) niche. Therefore, we examined how N-cadherin expression in HSCs relates to their function. We found that bone marrow (BM) cells highly expressing N-cadherin (N-cadherin(hi)) are not stem cells, being largely devoid of a Lineage(-)Sca1(+)cKit(+) population and unable to reconstitute hematopoietic lineages in irradiated recipient mice. Instead, long-term HSCs form distinct populations expressing N-cadherin at intermediate (N-cadherin(int)) or low (N-cadherin(lo)) levels. The minority N-cadherin(lo) population can robustly reconstitute the hematopoietic system, express genes that may prime them to mobilize, and predominate among HSCs mobilized from BM to spleen. The larger N-cadherin(int) population performs poorly in reconstitution assays when freshly isolated but improves in response to overnight in vitro culture. Their expression profile and lower cell-cycle entry rate suggest N-cadherin(int) cells are being held in reserve. Thus, differential N-cadherin expression reflects functional distinctions between two HSC subpopulations.

  14. Priming states of mind can affect disclosure of threatening self-information: Effects of self-affirmation, mortality salience, and attachment orientations.

    PubMed

    Davis, Deborah; Soref, Assaf; Villalobos, J Guillermo; Mikulincer, Mario

    2016-08-01

    Interviewers often face respondents reluctant to disclose sensitive, embarrassing or potentially damaging information. We explored effects of priming 5 states of mind on willingness to disclose: including 2 expected to facilitate disclosure (self-affirmation, attachment security), and 3 expected to inhibit disclosure (self-disaffirmation, attachment insecurity, mortality salience). Israeli Jewish participants completed a survey including a manipulation of 1 of these states of mind, followed by questions concerning hostile thoughts and behaviors toward the Israeli Arab outgroup, past minor criminal behaviors, and socially undesirable traits and behaviors. Self-affirmation led to more disclosures of all undesirable behaviors than neutral priming, whereas self-disaffirmation led to less disclosures. Mortality salience led to fewer disclosures of socially undesirable and criminal behaviors compared to neutral priming, but more disclosures of hostile thoughts and behaviors toward Israeli Arabs. Security priming facilitated disclosure of hostile attitudes toward Israeli Arabs. However, neither security nor insecurity priming had any other significant effects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  15. Photoionization of alkylphenothiazines in vesicles: Effects of the alkyl chain length and the vesicle surface charge

    SciTech Connect

    Sakaguchi, Masato; Hu, Ming; Kevan, L. )

    1990-01-25

    The photoionization of alkylphenothiazine (AP = alkylphenothiazine) in vesicles were observed by electron spin resonance (ESR) and electron spin echo modulation (ESEM) methods. Alkylphenothiazine derivatives including sodium 10-methylphenothiazinesulfonate (C{sub 1}PSO{sub 3}Na), sodium 10-dodecylphenothiazinesulfonate (C{sub 12}PSO{sub 3}Na), sodium 3-(10{prime}-phenothiazinyl)propane-1-sulfonate (PC{sub 3}SO{sub 3}Na), sodium 6-(10{prime}-phenothiazinyl)hexane-1-sulfonate (PC{sub 6}SO{sub 3}Na), and sodium 12-(10{prime}-phenothiazinyl)dodecane-1-sulfonate (PC{sub 12}SO{sub 3} Na) were synthesized and used to study the effects of the alkyl chain length, the position of the sulfonate group, and the vesicle surface charge on the photoionization. A single ESR spectrum due to the alkylphenothiazine cation radicals (AP{sup +}) was observed from rapidly frozen AP in dioctadecyldimethylammonium chloride (DODAC) or dihexadecyl phosphate (DHP) vesicles photoirradiated for 10 min with {lambda} > 300 nm. In DODAC vesicles with a positive surface charge, the photoionization yield of PC{sub 12}SO{sub 3}Na with a sulfonate group at the dodecyl chain end is higher than that of C{sub 12}PSO{sub 3}Na with a sulfonate group on the phenothiazine ring. The photoionization yields of AP having the sulfonate group at the alkyl chain end in DODAC vesicles increase with decreasing alkyl chain length. The highest photoionization yield was obtained from PC{sub 3}SO{sub 3}Na, which has the shortest alkyl chain in this study and has the sulfonate group at the end of the propyl chain. The photoionization yield of AP in DHP vesicles with a negative surface charge was not changed by added alkyl chains or the position of the sulfonate group in AP. The results are discussed in terms of the alkyl chain length, the position of the sulfonate group, and the vesicle surface charge.

  16. Theoretical description of the 2A/double prime/ and 2A/prime/ states of the peroxyformyl radical. [for air pollution and Mars atmospheric studies

    NASA Technical Reports Server (NTRS)

    Winter, N. W.; Goddard, W. A., III; Bender, C. F.

    1975-01-01

    Simple orbital ideas are used to describe the lowest two states of the peroxyformyl radical, and ab initio Hartree-Fock calculations in these states are reported. It is found that both states may be formed exothermically by association of O2 and HCO in their ground states; however, the excited state may decompose readily to OH and CO2. The possible role of such processes in oxidation of aldelydes is discussed.

  17. Theoretical description of the 2A/double prime/ and 2A/prime/ states of the peroxyformyl radical. [for air pollution and Mars atmospheric studies

    NASA Technical Reports Server (NTRS)

    Winter, N. W.; Goddard, W. A., III; Bender, C. F.

    1975-01-01

    Simple orbital ideas are used to describe the lowest two states of the peroxyformyl radical, and ab initio Hartree-Fock calculations in these states are reported. It is found that both states may be formed exothermically by association of O2 and HCO in their ground states; however, the excited state may decompose readily to OH and CO2. The possible role of such processes in oxidation of aldelydes is discussed.

  18. Prime Contract Awards Over $25,000 by Major System, Contractor and State, FY83.

    DTIC Science & Technology

    1983-01-01

    508 ENEROYSTICS CORP VIRaI R408 MGT SERVICES/PROGRAM MANAGEMENT-SUPPORT 2,059 EN RAd MGT SERVICES/SYSTEMS ENGINEERING 690 EN STATE TOTAL 2,749 EPSCO ...ANTENNA ASSOCIATES INC MASS 6940 COMMUNICATION TRAINING DEVICES 107 EPSCO INC MASS 5895 MISCELLANEOUS COMMUNICATION EQUIPMENT 34 GENERAL DYNAMICS CORP

  19. Granulosa cell-oocyte interactions: the phosphorylation of specific proteins in mouse oocytes at the germinal vesicle stage is dependent upon the differentiative state of companion somatic cells

    SciTech Connect

    Cecconi, S.; Tatone, C.; Buccione, R.; Mangia, F.; Colonna, R. )

    1991-05-01

    The role of granulosa cells in the regulation of mouse ovarian oocyte metabolism was investigated. Fully grown antral oocytes, isolated from surrounding cumulus cells, were cultured on monolayers of preantral granulosa cells in the presence of dbcAMP to prevent the resumption of meiosis. Under these conditions metabolic cooperativity was established between the two cell types as early as 1 hr after seeding. Moreover, cocultured oocytes phosphorylated two polypeptides of 74 and 21 kDa which are normally phosphorylated in follicle-enclosed growing oocytes but not in cumulus cell-enclosed fully grown oocytes at the germinal vesicle stage. When cocultured oocytes were allowed to resume meiosis, the 74 and 21 kDa proteins were synthesized but no longer phosphorylated even though intercellular coupling between the two cell types was maintained during radiolabeling. It appears therefore: (a) that the different protein kinase activity of growing and fully grown germinal vesicle-stage mouse oocytes is related to the differentiative state of granulosa cells, and (b) that the regulation of oocyte protein phosphorylation activity by granulosa cells is dependent on the meiotic stage of the oocyte.

  20. Use of BABA and INA As Activators of a Primed State in the Common Bean (Phaseolus vulgaris L.).

    PubMed

    Martínez-Aguilar, Keren; Ramírez-Carrasco, Gabriela; Hernández-Chávez, José Luis; Barraza, Aarón; Alvarez-Venegas, Raúl

    2016-01-01

    To survive in adverse conditions, plants have evolved complex mechanisms that "prime" their defense system to respond and adapt to stresses. Their competence to respond to such stresses fundamentally depends on its capacity to modulate the transcriptome rapidly and specifically. Thus, chromatin dynamics is a mechanism linked to transcriptional regulation and enhanced defense in plants. For example, in Arabidopsis, priming of the SA-dependent defense pathway is linked to histone lysine methylation. Such modifications could create a memory of the primary infection that is associated with an amplified gene response upon exposure to a second stress-stimulus. In addition, the priming status of a plant for induced resistance can be inherited to its offspring. However, analyses on the molecular mechanisms of generational and transgenerational priming in the common bean (Phaseolus vulagris L.), an economically important crop, are absent. Here, we provide evidence that resistance to P. syringae pv. phaseolicola infection was induced in the common bean with the synthetic priming activators BABA and INA. Resistance was assessed by evaluating symptom appearance, pathogen accumulation, changes in gene expression of defense genes, as well as changes in the H3K4me3 and H3K36me3 marks at the promoter-exon regions of defense-associated genes. We conclude that defense priming in the common bean occurred in response to BABA and INA and that these synthetic activators primed distinct genes for enhanced disease resistance. We hope that an understanding of the molecular changes leading to defense priming and pathogen resistance will provide valuable knowledge for producing disease-resistant crop varieties by exposing parental plants to priming activators, as well as to the development of novel plant protection chemicals that stimulate the plant's inherent disease resistance mechanisms.

  1. Wnt/β-catenin signaling promotes self-renewal and inhibits the primed state transition in naïve human embryonic stem cells.

    PubMed

    Xu, Zhuojin; Robitaille, Aaron M; Berndt, Jason D; Davidson, Kathryn C; Fischer, Karin A; Mathieu, Julie; Potter, Jennifer C; Ruohola-Baker, Hannele; Moon, Randall T

    2016-10-18

    In both mice and humans, pluripotent stem cells (PSCs) exist in at least two distinct states of pluripotency, known as the naïve and primed states. Our understanding of the intrinsic and extrinsic factors that enable PSCs to self-renew and to transition between different pluripotent states is important for understanding early development. In mouse embryonic stem cells (mESCs), Wnt proteins stimulate mESC self-renewal and support the naïve state. In human embryonic stem cells (hESCs), Wnt/β-catenin signaling is active in naïve-state hESCs and is reduced or absent in primed-state hESCs. However, the role of Wnt/β-catenin signaling in naïve hESCs remains largely unknown. Here, we demonstrate that inhibition of the secretion of Wnts or inhibition of the stabilization of β-catenin in naïve hESCs reduces cell proliferation and colony formation. Moreover, we show that addition of recombinant Wnt3a partially rescues cell proliferation in naïve hESCs caused by inhibition of Wnt secretion. Notably, inhibition of Wnt/β-catenin signaling in naïve hESCs did not cause differentiation. Instead, it induced primed hESC-like proteomic and metabolic profiles. Thus, our results suggest that naïve hESCs secrete Wnts that activate autocrine or paracrine Wnt/β-catenin signaling to promote efficient self-renewal and inhibit the transition to the primed state.

  2. An ab initio calculation of the zero-field splitting parameters of the 3A-double prime state of formaldehyde

    NASA Technical Reports Server (NTRS)

    Davidson, E. R.; Ellenbogen, J. C.; Langhoff, S. R.

    1980-01-01

    The spin dipole-dipole and spin-orbit contributions to the zero-field splitting of the 3A-double prime state of formaldehyde have been evaluated at the excited state experimental geometry. Ab initio CI wave functions were generated from a Dunning double zeta plus polarization bases set using 3A-double prime rhf orbitals. Twelve states of each symmetry were used to evaluate the second-order spin-orbit effect. The resulting values of D and E were 0.19 and 0.03 kayser with the principal magnetic axes rotated 36 deg from the CO bond. The values of alpha and beta relative to the inertial axes were calculated to be 0.03 and 0.01 kayser compared to the experimental values of 0.05 plus or minus 0.01 and 0.02 plus or minus 0.02 kayser.

  3. An ab initio calculation of the zero-field splitting parameters of the 3A-double prime state of formaldehyde

    NASA Technical Reports Server (NTRS)

    Davidson, E. R.; Ellenbogen, J. C.; Langhoff, S. R.

    1980-01-01

    The spin dipole-dipole and spin-orbit contributions to the zero-field splitting of the 3A-double prime state of formaldehyde have been evaluated at the excited state experimental geometry. Ab initio CI wave functions were generated from a Dunning double zeta plus polarization bases set using 3A-double prime rhf orbitals. Twelve states of each symmetry were used to evaluate the second-order spin-orbit effect. The resulting values of D and E were 0.19 and 0.03 kayser with the principal magnetic axes rotated 36 deg from the CO bond. The values of alpha and beta relative to the inertial axes were calculated to be 0.03 and 0.01 kayser compared to the experimental values of 0.05 plus or minus 0.01 and 0.02 plus or minus 0.02 kayser.

  4. Radiative decays of the psi prime to all-photon final states

    SciTech Connect

    Lee, R.A.

    1985-06-01

    Results of studies of selected radiative decays of the psi' to charmonium and non-charmonium states which decay into photons are presented. These studies were performed using a sample of 1.8 x 10/sup 6/ produced psi''s collected by the Crystal Ball detector at the SPEAR electron-positron storage ring. The branching ratios of the chi/sub 0/, chi/sub 2/, and eta'/sub c/ to two photons have been measured to be (4.5 +- 2.2 +- 2.0) x 10/sup -4/, (9.5 +- 2.9 +- 4.5) x 10/sup -4/ (first errors statistical, second systematic), and <1 x 10/sup -2/ (90% C.L.). The signal from the decay chain psi' ..-->.. ..gamma..chi/sub 0/, chi/sub 0/ ..-->.. ..pi../sup 0/..pi../sup 0/ has been observed with essentially no background. Using the observed line shape of the radiative photon in this reaction, the full width of the psi/sub 0/ has been found to be 8.8 +- 1.3 +- 1.5 MeV/c/sup 2/. In addition, the branching ratios of the chi/sub 0/ and chi/sub 2/ to ..pi../sup 0/..pi../sup 0/ have been measured to be (3.5 +- 0.3 +- 1.2) x 10/sup -3/ and (1.2 +- 0.2 +- 0.4) x 10/sup -3/; the branching ratios of the chi/sub 0/ and chi/sub 2/ to eta eta have been measured to be (2.8 +- 0.9 +- 1.3) x 10/sup -3/ and (8.4 +- 4.2 +- 4.0) x 10/sup -4/. The decays of the psi' to four non-charmonium states have been investigated. The branching ratios and upper limits of these decays have been normalized to the branching ratios of the corresponding decays from the J/psi which have been measured using a sample of 2.2 x 10/sup 6/ produced J/psi's collected by the Crystal Ball detector. The ratios of the psi' branching ratios to the J/psi branching ratios for the final states ..gamma..eta, ..gamma..eta', ..gamma..theta, and ..gamma..f have been measured to be <1.8%, <2.6%, <10 to 15%, and 9 +- 3%. These results are compared with the theoretical expectations of lowest-order quantum chromodynamics potential models. Substantial disagreement is found between theory and experiment.

  5. The Affective Regulation of Cognitive Priming

    PubMed Central

    Storbeck, Justin; Clore, Gerald L.

    2008-01-01

    Semantic and affective priming are classic effects observed in cognitive and social psychology, respectively. We discovered that affect regulates such priming effects. In Experiment 1, positive and negative moods were induced prior to one of three priming tasks; evaluation, categorization, or lexical decision. As predicted, positive affect led to both affective priming (evaluation task) and semantic priming (category and lexical decision tasks). However, negative affect inhibited such effects. In Experiment 2, participants in their natural affective state completed the same priming tasks as in Experiment 1. As expected, affective priming (evaluation task) and category priming (categorization and lexical decision tasks) were observed in such resting affective states. Hence, we conclude that negative affect inhibits semantic and affective priming. These results support recent theoretical models, which suggest that positive affect promotes associations among strong and weak concepts, and that negative affect impairs such associations (Kuhl, 2000; Clore & Storbeck, 2006). PMID:18410195

  6. Use of BABA and INA As Activators of a Primed State in the Common Bean (Phaseolus vulgaris L.)

    PubMed Central

    Martínez-Aguilar, Keren; Ramírez-Carrasco, Gabriela; Hernández-Chávez, José Luis; Barraza, Aarón; Alvarez-Venegas, Raúl

    2016-01-01

    To survive in adverse conditions, plants have evolved complex mechanisms that “prime” their defense system to respond and adapt to stresses. Their competence to respond to such stresses fundamentally depends on its capacity to modulate the transcriptome rapidly and specifically. Thus, chromatin dynamics is a mechanism linked to transcriptional regulation and enhanced defense in plants. For example, in Arabidopsis, priming of the SA-dependent defense pathway is linked to histone lysine methylation. Such modifications could create a memory of the primary infection that is associated with an amplified gene response upon exposure to a second stress-stimulus. In addition, the priming status of a plant for induced resistance can be inherited to its offspring. However, analyses on the molecular mechanisms of generational and transgenerational priming in the common bean (Phaseolus vulagris L.), an economically important crop, are absent. Here, we provide evidence that resistance to P. syringae pv. phaseolicola infection was induced in the common bean with the synthetic priming activators BABA and INA. Resistance was assessed by evaluating symptom appearance, pathogen accumulation, changes in gene expression of defense genes, as well as changes in the H3K4me3 and H3K36me3 marks at the promoter-exon regions of defense-associated genes. We conclude that defense priming in the common bean occurred in response to BABA and INA and that these synthetic activators primed distinct genes for enhanced disease resistance. We hope that an understanding of the molecular changes leading to defense priming and pathogen resistance will provide valuable knowledge for producing disease-resistant crop varieties by exposing parental plants to priming activators, as well as to the development of novel plant protection chemicals that stimulate the plant's inherent disease resistance mechanisms. PMID:27242854

  7. Morphological docking of secretory vesicles

    PubMed Central

    2010-01-01

    Calcium-dependent secretion of neurotransmitters and hormones is essential for brain function and neuroendocrine-signaling. Prior to exocytosis, neurotransmitter-containing vesicles dock to the target membrane. In electron micrographs of neurons and neuroendocrine cells, like chromaffin cells many synaptic vesicles (SVs) and large dense-core vesicles (LDCVs) are docked. For many years the molecular identity of the morphologically docked state was unknown. Recently, we resolved the minimal docking machinery in adrenal medullary chromaffin cells using embryonic mouse model systems together with electron-microscopic analyses and also found that docking is controlled by the sub-membrane filamentous (F-)actin. Currently it is unclear if the same docking machinery operates in synapses. Here, I will review our docking assay that led to the identification of the LDCV docking machinery in chromaffin cells and also discuss whether identical docking proteins are required for SV docking in synapses. PMID:20577884

  8. High salt primes a specific activation state of macrophages, M(Na).

    PubMed

    Zhang, Wu-Chang; Zheng, Xiao-Jun; Du, Lin-Juan; Sun, Jian-Yong; Shen, Zhu-Xia; Shi, Chaoji; Sun, Shuyang; Zhang, Zhiyuan; Chen, Xiao-Qing; Qin, Mu; Liu, Xu; Tao, Jun; Jia, Lijun; Fan, Heng-Yu; Zhou, Bin; Yu, Ying; Ying, Hao; Hui, Lijian; Liu, Xiaolong; Yi, Xianghua; Liu, Xiaojing; Zhang, Lanjing; Duan, Sheng-Zhong

    2015-08-01

    High salt is positively associated with the risk of many diseases. However, little is known about the mechanisms. Here we showed that high salt increased proinflammatory molecules, while decreased anti-inflammatory and proendocytic molecules in both human and mouse macrophages. High salt also potentiated lipopolysaccharide-induced macrophage activation and suppressed interleukin 4-induced macrophage activation. High salt induced the proinflammatory aspects by activating p38/cFos and/or Erk1/2/cFos pathways, while inhibited the anti-inflammatory and proendocytic aspects by Erk1/2/signal transducer and activator of transcription 6 pathway. Consistent with the in vitro results, high-salt diet increased proinflammatory gene expression of mouse alveolar macrophages. In mouse models of acute lung injury, high-salt diet aggravated lipopolysaccharide-induced pulmonary macrophage activation and inflammation in lungs. These results identify a novel macrophage activation state, M(Na), and high salt as a potential environmental risk factor for lung inflammation through the induction of M(Na).

  9. High salt primes a specific activation state of macrophages, M(Na)

    PubMed Central

    Zhang, Wu-Chang; Zheng, Xiao-Jun; Du, Lin-Juan; Sun, Jian-Yong; Shen, Zhu-Xia; Shi, Chaoji; Sun, Shuyang; Zhang, Zhiyuan; Chen, Xiao-qing; Qin, Mu; Liu, Xu; Tao, Jun; Jia, Lijun; Fan, Heng-yu; Zhou, Bin; Yu, Ying; Ying, Hao; Hui, Lijian; Liu, Xiaolong; Yi, Xianghua; Liu, Xiaojing; Zhang, Lanjing; Duan, Sheng-Zhong

    2015-01-01

    High salt is positively associated with the risk of many diseases. However, little is known about the mechanisms. Here we showed that high salt increased proinflammatory molecules, while decreased anti-inflammatory and proendocytic molecules in both human and mouse macrophages. High salt also potentiated lipopolysaccharide-induced macrophage activation and suppressed interleukin 4-induced macrophage activation. High salt induced the proinflammatory aspects by activating p38/cFos and/or Erk1/2/cFos pathways, while inhibited the anti-inflammatory and proendocytic aspects by Erk1/2/signal transducer and activator of transcription 6 pathway. Consistent with the in vitro results, high-salt diet increased proinflammatory gene expression of mouse alveolar macrophages. In mouse models of acute lung injury, high-salt diet aggravated lipopolysaccharide-induced pulmonary macrophage activation and inflammation in lungs. These results identify a novel macrophage activation state, M(Na), and high salt as a potential environmental risk factor for lung inflammation through the induction of M(Na). PMID:26206316

  10. Simultaneous measurements of (p,p{prime}) and (p,p{prime}{gamma}) observables for 1{sup +} states in {sup 12}C at 200 MeV

    SciTech Connect

    Wells, S.P.; Wissink, S.W.; Bacher, A.D.

    1993-10-01

    We have made measurements of the ({tilde p}, {tilde p}`) singles observables d{sigma}/d{Sigma} two linear combinations of D{sub LL`}, D{sub LS`}, D{sub SL`}, and D{sub SS`}, as well as the coincident ({tilde p}, p` {gamma}) yields and asymmetries (including the sideways and longitudinal analyzing powers D{sub 0S} and D{sub 0L}) for the two dominant 1{sup +} states in {sup 12}C over a laboratory angle range of {theta}{sub p} = 5{degrees} to 15{degrees} for an incident proton energy of 200 MeV. These measurements were performed using IUCF`s K600 spectrometer and associated FPP in conjunction with 4 19-packs of BaF{sub 2} provided by ORNL. Contained in these data is sufficient information for a model-independent determination of the scattering amplitude for the 15.11 MeV, 1{sup +}, T=1 state in {sup 12}C. Comparison of the data with relativistic and nonrelativistic calculations will be shown.

  11. Adhesion of Polymer Vesicles

    NASA Astrophysics Data System (ADS)

    Lin, John J.; Bates, Frank S.; Hammer, Daniel A.; Silas, James A.

    2005-07-01

    The adhesion and bending modulus of polybutadiene-poly(ethylene oxide) block copolymer vesicles made from a bidisperse mixture of polymers is measured using micropipette aspiration. The adhesion energy between biotinylated vesicles and avidin beads is modeled by incorporating the extension of the adhesive ligands above the surface brush of the vesicle according to the blob model of bidisperse polymer mixtures of Komura and Safran assuming the polymer brush at the surface of the vesicle is compact. The same model accurately reproduces the scaling of the bending modulus with polymer composition.

  12. Differential Regulation of Synaptic Vesicle Tethering and Docking by UNC-18 and TOM-1.

    PubMed

    Gracheva, Elena O; Maryon, Ed B; Berthelot-Grosjean, Martine; Richmond, Janet E

    2010-01-01

    The assembly of SNARE complexes between syntaxin, SNAP-25 and synaptobrevin is required to prime synaptic vesicles for fusion. Since Munc18 and tomosyn compete for syntaxin interactions, the interplay between these proteins is predicted to be important in regulating synaptic transmission. We explored this possibility, by examining genetic interactions between C. elegans unc-18(Munc18), unc-64(syntaxin) and tom-1(tomosyn). We have previously demonstrated that unc-18 mutants have reduced synaptic transmission, whereas tom-1 mutants exhibit enhanced release. Here we show that the unc-18 mutant release defect is associated with loss of two morphologically distinct vesicle pools; those tethered within 25 nm of the plasma membrane and those docked with the plasma membrane. In contrast, priming defective unc-13 mutants accumulate tethered vesicles, while docked vesicles are greatly reduced, indicating tethering is UNC-18-dependent and occurs in the absence of priming. C. elegans unc-64 mutants phenocopy unc-18 mutants, losing both tethered and docked vesicles, whereas overexpression of open syntaxin preferentially increases vesicle docking, suggesting UNC-18/closed syntaxin interactions are responsible for vesicle tethering. Given the competition between vertebrate tomosyn and Munc18, for syntaxin binding, we hypothesized that C. elegans TOM-1 may inhibit both UNC-18-dependent vesicle targeting steps. Consistent with this hypothesis, tom-1 mutants exhibit enhanced UNC-18 plasma membrane localization and a concomitant increase in both tethered and docked synaptic vesicles. Furthermore, in tom-1;unc-18 double mutants the docked, primed vesicle pool is preferentially rescued relative to unc-18 single mutants. Together these data provide evidence for the differential regulation of two vesicle targeting steps by UNC-18 and TOM-1 through competitive interactions with syntaxin.

  13. CAPS and Munc13: CATCHRs that SNARE Vesicles

    PubMed Central

    James, Declan J.; Martin, Thomas F. J.

    2013-01-01

    CAPS (Calcium-dependent Activator Protein for Secretion, aka CADPS) and Munc13 (Mammalian Unc-13) proteins function to prime vesicles for Ca2+-triggered exocytosis in neurons and neuroendocrine cells. CAPS and Munc13 proteins contain conserved C-terminal domains that promote the assembly of SNARE complexes for vesicle priming. Similarities of the C-terminal domains of CAPS/Munc13 proteins with Complex Associated with Tethering Containing Helical Rods domains in multi-subunit tethering complexes (MTCs) have been reported. MTCs coordinate multiple interactions for SNARE complex assembly at constitutive membrane fusion steps. We review aspects of these diverse tethering and priming factors to identify common operating principles. PMID:24363652

  14. Synaptic Vesicle Endocytosis

    PubMed Central

    Saheki, Yasunori; De Camilli, Pietro

    2012-01-01

    Neurons can sustain high rates of synaptic transmission without exhausting their supply of synaptic vesicles. This property relies on a highly efficient local endocytic recycling of synaptic vesicle membranes, which can be reused for hundreds, possibly thousands, of exo-endocytic cycles. Morphological, physiological, molecular, and genetic studies over the last four decades have provided insight into the membrane traffic reactions that govern this recycling and its regulation. These studies have shown that synaptic vesicle endocytosis capitalizes on fundamental and general endocytic mechanisms but also involves neuron-specific adaptations of such mechanisms. Thus, investigations of these processes have advanced not only the field of synaptic transmission but also, more generally, the field of endocytosis. This article summarizes current information on synaptic vesicle endocytosis with an emphasis on the underlying molecular mechanisms and with a special focus on clathrin-mediated endocytosis, the predominant pathway of synaptic vesicle protein internalization. PMID:22763746

  15. On the Computing Potential of Intracellular Vesicles

    PubMed Central

    Mayne, Richard; Adamatzky, Andrew

    2015-01-01

    Collision-based computing (CBC) is a form of unconventional computing in which travelling localisations represent data and conditional routing of signals determines the output state; collisions between localisations represent logical operations. We investigated patterns of Ca2+-containing vesicle distribution within a live organism, slime mould Physarum polycephalum, with confocal microscopy and observed them colliding regularly. Vesicles travel down cytoskeletal ‘circuitry’ and their collisions may result in reflection, fusion or annihilation. We demonstrate through experimental observations that naturally-occurring vesicle dynamics may be characterised as a computationally-universal set of Boolean logical operations and present a ‘vesicle modification’ of the archetypal CBC ‘billiard ball model’ of computation. We proceed to discuss the viability of intracellular vesicles as an unconventional computing substrate in which we delineate practical considerations for reliable vesicle ‘programming’ in both in vivo and in vitro vesicle computing architectures and present optimised designs for both single logical gates and combinatorial logic circuits based on cytoskeletal network conformations. The results presented here demonstrate the first characterisation of intracelluar phenomena as collision-based computing and hence the viability of biological substrates for computing. PMID:26431435

  16. On the Computing Potential of Intracellular Vesicles.

    PubMed

    Mayne, Richard; Adamatzky, Andrew

    2015-01-01

    Collision-based computing (CBC) is a form of unconventional computing in which travelling localisations represent data and conditional routing of signals determines the output state; collisions between localisations represent logical operations. We investigated patterns of Ca2+-containing vesicle distribution within a live organism, slime mould Physarum polycephalum, with confocal microscopy and observed them colliding regularly. Vesicles travel down cytoskeletal 'circuitry' and their collisions may result in reflection, fusion or annihilation. We demonstrate through experimental observations that naturally-occurring vesicle dynamics may be characterised as a computationally-universal set of Boolean logical operations and present a 'vesicle modification' of the archetypal CBC 'billiard ball model' of computation. We proceed to discuss the viability of intracellular vesicles as an unconventional computing substrate in which we delineate practical considerations for reliable vesicle 'programming' in both in vivo and in vitro vesicle computing architectures and present optimised designs for both single logical gates and combinatorial logic circuits based on cytoskeletal network conformations. The results presented here demonstrate the first characterisation of intracelluar phenomena as collision-based computing and hence the viability of biological substrates for computing.

  17. The Pharmacology of Nociceptor Priming

    PubMed Central

    Kandasamy, Ram

    2015-01-01

    Nociceptors and neurons in the central nervous system (CNS) that receive nociceptive input show remarkable plasticity in response to injury. This plasticity is thought to underlie the development of chronic pain states. Hence, further understanding of the molecular mechanisms driving and maintaining this plasticity has the potential to lead to novel therapeutic approaches for the treatment of chronic pain states. An important concept in pain plasticity is the presence and persistence of “hyperalgesic priming.” This priming arises from an initial injury and results in a remarkable susceptibility to normally subthreshold noxious inputs causing a prolonged pain state in primed animals. Here we describe our current understanding of how this priming is manifested through changes in signaling in the primary nociceptor as well as through memory like alterations at CNS synapses. Moreover, we discuss how commonly utilized analgesics, such as opioids, enhance priming therefore potentially contributing to the development of persistent pain states. Finally we highlight where these priming models draw parallels to common human chronic pain conditions. Collectively, these advances in our understanding of pain plasticity reveal a variety of targets for therapeutic intervention with the potential to reverse rather than palliate chronic pain states. PMID:25846612

  18. The pharmacology of nociceptor priming.

    PubMed

    Kandasamy, Ram; Price, Theodore J

    2015-01-01

    Nociceptors and neurons in the central nervous system (CNS) that receive nociceptive input show remarkable plasticity in response to injury. This plasticity is thought to underlie the development of chronic pain states. Hence, further understanding of the molecular mechanisms driving and maintaining this plasticity has the potential to lead to novel therapeutic approaches for the treatment of chronic pain states. An important concept in pain plasticity is the presence and persistence of "hyperalgesic priming." This priming arises from an initial injury and results in a remarkable susceptibility to normally subthreshold noxious inputs causing a prolonged pain state in primed animals. Here we describe our current understanding of how this priming is manifested through changes in signaling in the primary nociceptor as well as through memory like alterations at CNS synapses. Moreover, we discuss how commonly utilized analgesics, such as opioids, enhance priming therefore potentially contributing to the development of persistent pain states. Finally we highlight where these priming models draw parallels to common human chronic pain conditions. Collectively, these advances in our understanding of pain plasticity reveal a variety of targets for therapeutic intervention with the potential to reverse rather than palliate chronic pain states.

  19. Dollar Summary of Prime Contract Awards by Contractor, State or Country, and Place, FY83, Part 1 (A&A Chemical Toilet Rentals-Gillespie Construction Co.)

    DTIC Science & Technology

    1983-01-01

    1L 11w1. MICROCOPY RESOLUTION TESI CHARI NATION. (TUH AO’I NP PRIME-CONTRACTS BY CONTRACTOR, STATE, AND CITY - (OCT 82 - SEP 83) Itir$ ",’? (0(4I.L ARS...INC ORANGE CALIFORNIA 44 14 44 44 FORMA RAPID CONSTRUCTION CORP PONCE PUERTO RCO 224 224 7OPMA RAP10 CONSTRUCTION C00Sp RnOSEVELT ROAD3 PUERTO RCO 60...o R C CONTRACTING INC JACKSONVILLE FLORIDA 58 56 58 58 S R 0 CO WARMINSTER PA 1,084 1,084 1 084 1,084 o R G ENGINEERING INC FORT BUCHANAN PUERTO RCO

  20. The transition of mouse pluripotent stem cells from the naïve to the primed state requires Fas signaling through 3-O sulfated heparan sulfate structures recognized by the HS4C3 antibody

    SciTech Connect

    Hirano, Kazumi; Van Kuppevelt, Toin H.; Nishihara, Shoko

    2013-01-18

    Highlights: ► Fas transcript increases during the transition from the naïve to the primed state. ► 3OST-5 transcript, the HS4C3 epitope synthesis gene, increases during the transition. ► Fas signaling regulates the transition from the naïve to the primed state. ► HS4C3-binding epitope regulates the transition from the naïve to the primed state. ► Fas signaling is regulated by the HS4C3 epitope during the transition. -- Abstract: The characteristics of pluripotent embryonic stem cells of human and mouse are different. The properties of human embryonic stem cells (hESCs) are similar to those of mouse epiblast stem cells (mEpiSCs), which are in a later developmental pluripotency state, the so-called “primed state” compared to mouse embryonic stem cells (mESCs) which are in a naïve state. As a result of the properties of the primed state, hESCs proliferate slowly, cannot survive as single cells, and can only be transfected with genes at low efficiency. Generating hESCs in the naïve state is necessary to overcome these problems and allow their application in regenerative medicine. Therefore, clarifying the mechanism of the transition between the naïve and primed states in pluripotent stem cells is important for the establishment of stable methods of generating naïve state hESCs. However, the signaling pathways which contribute to the transition between the naïve and primed states are still unclear. In this study, we carried out induction from mESCs to mEpiSC-like cells (mEpiSCLCs), and observed an increase in the activation of Fas signaling during the induction. The expression of Fgf5, an epiblast marker, was diminished by inhibition of Fas signaling using the caspase-8 and -3 blocking peptides, IETD and DEVD, respectively. Furthermore, during the induction, we observed increased expression of 3-O sulfated heparan sulfate (HS) structures synthesized by HS 3-O-sulfotransferase (3OST), which are recognized by the HS4C3 antibody (HS4C3-binding epitope

  1. Vesicle trafficking and cell surface membrane patchiness.

    PubMed Central

    Tang, Q; Edidin, M

    2001-01-01

    Membrane proteins and lipids often appear to be distributed in patches on the cell surface. These patches are often assumed to be membrane domains, arising from specific molecular associations. However, a computer simulation (Gheber and Edidin, 1999) shows that membrane patchiness may result from a combination of vesicle trafficking and dynamic barriers to lateral mobility. The simulation predicts that the steady-state patches of proteins and lipids seen on the cell surface will decay if vesicle trafficking is inhibited. To test this prediction, we compared the apparent sizes and intensities of patches of class I HLA molecules, integral membrane proteins, before and after inhibiting endocytic vesicle traffic from the cell surface, either by incubation in hypertonic medium or by expression of a dominant-negative mutant dynamin. As predicted by the simulation, the apparent sizes of HLA patches increased, whereas their intensities decreased after endocytosis and vesicle trafficking were inhibited. PMID:11423406

  2. Vesicle extrusion in nanopores

    NASA Astrophysics Data System (ADS)

    Joóos, B. Éla; Bertrand, Martin; Ouellet, S. Ébastien

    2010-03-01

    Monodisperse vesicles of nearly circular shape or liposomes are used as drug delivery systems. Their fabrication involves repeated passage of large vesicles through small pores. At each passage the vesicle ruptures and the fragments reform into smaller vesicles. We report on the last stages of the process where small liposomes are pushed by pressure differences into nano-sized pores, and we study the stress distribution along the lipid bilayer to determine the rupture lines. This is done by performing coarse grained Molecular Dynamics simulations. We have developed a technique to measure the stress in the membrane based on a tessellation of the surface which allows us to monitor the local area per lipid fluctuations. The results show subtle and complex flow phenomena. We can predict the final size distribution after many passages. Comparisons will be made with existing experimental data.

  3. Pulling on adhered vesicles

    NASA Astrophysics Data System (ADS)

    Smith, Ana-Suncana; Goennenwein, Stefanie; Lorz, Barbara; Seifert, Udo; Sackmann, Erich

    2004-03-01

    A theoretical model describing pulling of vesicles adhered in a contact potential has been developed. Two different regimes have been recognized. For weak to middle-strength adhesive potentials, locally stable shapes are found in a range of applied forces, separated from the free shape by an energy barrier. The phase diagram contains regions with either a unique bound shape or an additional meta-stable shape. Upon pulling, these shapes unbind discontinuously since the vesicle disengage from the surface while still possessing a finite adhesion area (Smith 2003a). In a strong adhesion regime, a competition between adhesion and tether formation is observed. A critical onset force is identified where a tether spontaneously appears as a part of a second order shape transition. Further growth of a tether is followed by a detachment process which terminates at a finite force when a vesicle continuously unbinds from the substrate (Smith 2003b). Both critical forces, as well as all shape parameters, are calculated as a function of the reduced volume and the strength of adhesive potential. Analogous experimental study has been performed where a vertical magnetic tweezers are used in combination with micro-interferometric and confocal techniques to reproduce the same symmetry as in the theoretical investigation. Giant vesicles are bound to the substrate by numerous specific bonds formed between ligands and receptors incorporated into the vesicle and the substrate, respectively. Application of a constant force is inducing a new thermodynamic equilibrium of the system where the vesicle is partially unbound from the substrate (Goennenwein 2003). The shapes of vesicles are compared prior and during application of the force. Very good agreement is obtained, particularly in the middle-strength adhesion regime (Smith 2003c). References: 1. A.-S. Smith, E. Sackmann, U. Seifert: Effects of a pulling force on the shape of a bound vesicle, Europhys. Lett., 64, 2 (2003). 2. A.-S. Smith

  4. Kinetic regulation of coated vesicle secretion

    PubMed Central

    Foret, Lionel; Sens, Pierre

    2008-01-01

    The secretion of vesicles for intracellular transport often relies on the aggregation of specialized membrane-bound proteins into a coat able to curve cell membranes. The nucleation and growth of a protein coat is a kinetic process that competes with the energy-consuming turnover of coat components between the membrane and the cytosol. We propose a generic kinetic description of coat assembly and the formation of coated vesicles and discuss its implication to the dynamics of COP vesicles that traffic within the Golgi and with the endoplasmic reticulum. We show that stationary coats of fixed area emerge from the competition between coat growth and the recycling of coat components, in a fashion resembling the treadmilling of cytoskeletal filaments. We further show that the turnover of coat components allows for a highly sensitive switching mechanism between a quiescent and a vesicle producing membrane, upon a slowing down of the exchange kinetics. We claim that the existence of this switching behavior, also triggered by factors, such as the presence of cargo and variation of the membrane mechanical tension, allows for efficient regulation of vesicle secretion. We propose a model, supported by different experimental observations, in which vesiculation of secretory membranes is impaired by the energy-consuming desorption of coat proteins, until the presence of cargo or other factors triggers a dynamical switch into a vesicle producing state. PMID:18824695

  5. Problems with Primes

    ERIC Educational Resources Information Center

    Melrose, Tim; Scott, Paul

    2005-01-01

    This article discusses prime numbers, defined as integers greater than 1 that are divisible only by only themselves and the number 1. A positive integer greater than 1 that is not a prime is called composite. The number 1 itself is considered neither prime nor composite. As the name suggests, prime numbers are one of the most basic but important…

  6. Learning about Primes

    ERIC Educational Resources Information Center

    McEachran, Alec

    2008-01-01

    In this article, the author relates his unhappy experience in learning about prime numbers at secondary school. To introduce primes, a teacher first told students a definition of a prime number, then students were taught how to find prime numbers. Students defined and listed them and at some later point were tested on their memory of both the…

  7. Macroscopic model of phospholipid vesicle spreading and rupture.

    PubMed

    Efremov, A; Mauro, J C; Raghavan, S

    2004-07-06

    We present a macroscopic model for the spreading and rupture of a spherical lipid vesicle on a flat, isotropic, hydrophilic surface. Formulas for the free energy of the initial and final states are derived, and the details of spreading pathways are examined. We show that the activation barrier for vesicle rupture is too large to be overcome by thermal fluctuations at room temperature and the final configuration is more likely to consist of a deflated vesicle. In order for the vesicle to rupture into a planar bilayer, it would have to be aided by increased temperature, application of an external force, or preparation of a mixed hydrophilic/ hydrophobic surface.

  8. The primed SNARE–complexin–synaptotagmin complex for neuronal exocytosis

    DOE PAGES

    Zhou, Qiangjun; Zhou, Peng; Wang, Austin L.; ...

    2017-08-16

    Synaptotagmin, complexin, and neuronal SNARE (soluble N-ethylmaleimide sensitive factor attachment protein receptor) proteins mediate evoked synchronous neurotransmitter release, but the molecular mechanisms mediating the cooperation between these molecules remain unclear. Here we determine crystal structures of the primed pre-fusion SNARE–complexin–synaptotagmin-1 complex. These structures reveal an unexpected tripartite interface between synaptotagmin-1 and both the SNARE complex and complexin. Simultaneously, a second synaptotagmin-1 molecule interacts with the other side of the SNARE complex via the previously identified primary interface. Mutations that disrupt either interface in solution also severely impair evoked synchronous release in neurons, suggesting that both interfaces are essential for themore » primed pre-fusion state. Ca2+ binding to the synaptotagmin-1 molecules unlocks the complex, allows full zippering of the SNARE complex, and triggers membrane fusion. In conclusion, the tripartite SNARE–complexin–synaptotagmin-1 complex at a synaptic vesicle docking site has to be unlocked for triggered fusion to start, explaining the cooperation between complexin and synaptotagmin-1 in synchronizing evoked release on the sub-millisecond timescale.« less

  9. Prime Contract Awards Alphabetically by Contractor, by State or Country, and Place. Part 16 (Panhandle Food Sales-Ray Gene Electric Co Inc)

    DTIC Science & Technology

    1990-01-01

    AD-A236 466 1990 ANNUAL PRIME CONTRACTS AWARDS ALPHABETICALLY BY CONTRACTOR, BY STATE OR COUNTRY, AND PLACE. PT-16 (PANHANDLE FOOD SALES-RAY GENE ...4 I-l e~ I 0 MM 0)1 47470:14710) 0) 0) 0) I" gene , I LA 4 00 0) co -4 -FF- F- C (D <r- 0CD I~ gene , U0 -4 0. C4 0> 0D-4-4-40 C> C- N0 -4 (n L-4 cn...LW ,U ’L a) I CIme 𔃺" 0)0)100)0)10)0) (00 0 Ei(Cn" cc cc c c c c c c c c c 410mc’ " ::U. C 001. C00 r-0C0C r00 C w izI0’ M" ~ 000000 , . > .0 000 s-s

  10. Hyperviscous diblock copolymer vesicles

    NASA Astrophysics Data System (ADS)

    Dimova, R.; Seifert, U.; Pouligny, B.; Förster, S.; Döbereiner, H.-G.

    2002-03-01

    Giant vesicles prepared from the diblock copolymer polybutadien-b-polyethyleneoxide (PB-PEO) exhibit a shear surface viscosity, which is about 500 times higher than those found in common phospholipid bilayers. Our result constitutes the first direct measurement of the shear surface viscosity of such polymersomes. At the same time, we measure bending and stretching elastic constants, which fall in the range of values typical for lipid membranes. Pulling out a tether from an immobilized polymersome and following its relaxation back to the vesicle body provides an estimate of the viscous coupling between the two monolayers composing the polymer membrane. The detected intermonolayer friction is about an order of magnitude higher than the characteristic one for phospholipid membranes. Polymersomes are tough vesicles with a high lysis tension. This, together with their robust rheological properties, makes them interesting candidates for a number of technological applications.

  11. Critical dynamics of vesicle stretching transition in elongational flow.

    PubMed

    Kantsler, Vasiliy; Segre, Enrico; Steinberg, Victor

    2008-07-25

    We present results on the stretching of single tubular vesicles in an elongation flow toward dumbbell shapes, and on their relaxation. A critical strain rate epsilonc exists; for strain rates epsilonvesicle remains tubular but fluctuates, though its steady state extension increases with the strain rate epsilon. Above epsilonc, first a shape transition to dumbbell occurs, and then high order shape modes become unstable, leading to a pearling state. We have quantitatively characterized the transition and found a scaling of epsilonc with the system parameters. A remarkable feature of vesicle tube behavior around the critical point is a slowdown of the vesicle relaxation to the final extended state in the vesicle stretching. Such feature is similar to that found in continuous phase transitions and to the critical effects recently observed for polymer molecules near the coil-stretch transition in elongation flow.

  12. Vesicles in Poiseuille flow.

    PubMed

    Danker, Gerrit; Vlahovska, Petia M; Misbah, Chaouqi

    2009-04-10

    Blood microcirculation critically depends on the migration of red cells towards the flow centerline. We identify theoretically the ratio of the inner over the outer fluid viscosities lambda as a key parameter. At low lambda, the vesicle deforms into a tank-treading ellipsoid shape far away from the flow centerline. The migration is always towards the flow centerline, unlike drops. Above a critical lambda, the vesicle tumbles or breaths and migration is suppressed. A surprising coexistence of two types of shapes at the centerline, a bulletlike and a parachutelike shape, is predicted.

  13. Descendants of primed Arabidopsis plants exhibit resistance to biotic stress.

    PubMed

    Slaughter, Ana; Daniel, Xavier; Flors, Victor; Luna, Estrella; Hohn, Barbara; Mauch-Mani, Brigitte

    2012-02-01

    An attack of plants by pathogens or treatment with certain resistance-inducing compounds can lead to the establishment of a unique primed state of defense. Primed plants show enhanced defense reactions upon further challenge with biotic or abiotic stress. Here, we report that the primed state in Arabidopsis (Arabidopsis thaliana) is still functional in the next generation without additional treatment. We compared the reactions of Arabidopsis plants that had been either primed with β-amino-butyric acid (BABA) or with an avirulent isolate of the bacteria Pseudomonas syringae pv tomato (PstavrRpt2). The descendants of primed plants showed a faster and higher accumulation of transcripts of defense-related genes in the salicylic acid signaling pathway and enhanced disease resistance upon challenge inoculation with a virulent isolate of P. syringae. In addition, the progeny of primed plants was also more resistant against the oomycete pathogen Hyaloperonospora arabidopsidis. When transgenerationally primed plants were subjected to an additional priming treatment, their descendants displayed an even stronger primed phenotype, suggesting that plants can inherit a sensitization for the priming phenomenon. Interestingly, this primed to be primed phenotype was much reduced in the Arabidopsis β-amino-butyric acid priming mutant ibs1 (induced BABA sterility1). Our results demonstrate that the primed state of plants is transferred to their progeny and confers improved protection from pathogen attack as compared to the descendants of unprimed plants.

  14. The fluorescence intensity of the lipophilic probe N-phenyl-1-naphthylamine responds to the oxidation-reduction state of the respiratory chain in everted membrane vesicles of Escherichia coli.

    PubMed

    Sedgwick, E G; Bragg, P D

    1987-06-22

    N-Phenyl-1-naphthylamine (NPN), a reagent which has been used previously to probe the fluidity or microviscosity of the membrane lipids of intact cells of Escherichia coli, was found to respond to metabolic changes in everted inner membrane vesicles from this organism. NPN was bound to the vesicles to produce a steady-state level of fluorescence intensity. Addition of substrate or ATP did not alter the fluorescence. However, following complete removal of oxygen from the medium by oxidation of substrate through the respiratory chain, there was an increase in the fluorescence of NPN. Reoxidation of the components of the respiratory chain by the addition of oxygen, ferricyanide, fumarate or nitrate decreased fluorescence to the steady-state level until the oxidant had been completely reduced. The fluorescence changes were insensitive to the state of energization of the membrane. It is proposed that NPN responds to the state of reduction of components of the respiratory chain either directly by reacting with a component of the chain or indirectly through an effect transmitted to the membrane by a change in the conformation of respiratory chain components.

  15. Multiple Phenotypic Changes Define Neutrophil Priming.

    PubMed

    Miralda, Irina; Uriarte, Silvia M; McLeish, Kenneth R

    2017-01-01

    Exposure to pro-inflammatory cytokines, chemokines, mitochondrial contents, and bacterial and viral products induces neutrophils to transition from a basal state into a primed one, which is currently defined as an enhanced response to activating stimuli. Although, typically associated with enhanced generation of reactive oxygen species (ROS) by the NADPH oxidase, primed neutrophils show enhanced responsiveness of exocytosis, NET formation, and chemotaxis. Phenotypic changes associated with priming also include activation of a subset of functions, including adhesion, transcription, metabolism, and rate of apoptosis. This review summarizes the breadth of phenotypic changes associated with priming and reviews current knowledge of the molecular mechanisms behind those changes. We conclude that the current definition of priming is too restrictive. Priming represents a combination of enhanced responsiveness and activated functions that regulate both adaptive and innate immune responses.

  16. Multiple Phenotypic Changes Define Neutrophil Priming

    PubMed Central

    Miralda, Irina; Uriarte, Silvia M.; McLeish, Kenneth R.

    2017-01-01

    Exposure to pro-inflammatory cytokines, chemokines, mitochondrial contents, and bacterial and viral products induces neutrophils to transition from a basal state into a primed one, which is currently defined as an enhanced response to activating stimuli. Although, typically associated with enhanced generation of reactive oxygen species (ROS) by the NADPH oxidase, primed neutrophils show enhanced responsiveness of exocytosis, NET formation, and chemotaxis. Phenotypic changes associated with priming also include activation of a subset of functions, including adhesion, transcription, metabolism, and rate of apoptosis. This review summarizes the breadth of phenotypic changes associated with priming and reviews current knowledge of the molecular mechanisms behind those changes. We conclude that the current definition of priming is too restrictive. Priming represents a combination of enhanced responsiveness and activated functions that regulate both adaptive and innate immune responses. PMID:28611952

  17. Complexity of vesicle microcirculation

    NASA Astrophysics Data System (ADS)

    Kaoui, B.; Tahiri, N.; Biben, T.; Ez-Zahraouy, H.; Benyoussef, A.; Biros, G.; Misbah, C.

    2011-10-01

    This study focuses numerically on dynamics in two dimensions of vesicles in microcirculation. The method used is based on boundary integral formulation. This study is inspired by the behavior of red blood cells (RBCs) in the microvasculature. Red RBCs carry oxygen from the lungs and deliver it through the microvasculature. The shape adopted by RBCs can affect blood flow and influence oxygen delivery. Our simulation using vesicles (a simple model for RBC) reveals unexpected complexity as compared to the case where a purely unbounded Poiseuille flow is considered [Kaoui, Biros, and Misbah, Phys. Rev. Lett.10.1103/PhysRevLett.103.188101 103, 188101 (2009)]. In sufficiently large channels (in the range of 100μm; the vesicle size and its reduced volume are taken in the range of those of a human RBC), such as arterioles, a slipperlike (asymmetric) shape prevails. A parachutelike (symmetric) shape is adopted in smaller channels (in the range of 20μm, as in venules), but this shape loses stability and again changes to a pronounced slipperlike morphology in channels having a size typical of capillaries (5-10 μm). Stiff membranes, mimicking malaria infection, for example, adopt a centered or off-centered snakelike locomotion instead (the denomination snaking is used for this regime). A general scenario of how and why vesicles adopt their morphologies and dynamics among several distinct possibilities is provided. This finding potentially points to nontrivial RBCs dynamics in the microvasculature.

  18. Motor Priming in Neurorehabilitation

    PubMed Central

    Stoykov, Mary Ellen; Madhavan, Sangeetha

    2014-01-01

    Priming is a type of implicit learning wherein a stimulus prompts a change in behavior. Priming has been long studied in the field of psychology. More recently, rehabilitation researchers have studied motor priming as a possible way to facilitate motor learning. For example, priming of the motor cortex is associated with changes in neuroplasticity that are associated with improvements in motor performance. Of the numerous motor priming paradigms under investigation, only a few are practical for the current clinical environment, and the optimal priming modalities for specific clinical presentations are not known. Accordingly, developing an understanding of the various types of motor priming paradigms and their underlying neural mechanisms is an important step for therapists in neurorehabilitation. Most importantly, an understanding of the methods and their underlying mechanisms is essential for optimizing rehabilitation outcomes. The future of neurorehabilitation is likely to include these priming methods, which are delivered prior to or in conjunction with primary neurorehabilitation therapies. In this Special Interest article we discuss those priming paradigms that are supported by the greatest amount of evidence including: (i) stimulation-based priming, (ii) motor imagery and action observation, (iii) sensory priming, (iv) movement-based priming, and (v) pharmacological priming. PMID:25415551

  19. Repetition Priming in Music

    ERIC Educational Resources Information Center

    Hutchins, Sean; Palmer, Caroline

    2008-01-01

    The authors explore priming effects of pitch repetition in music in 3 experiments. Musically untrained participants heard a short melody and sang the last pitch of the melody as quickly as possible. Each experiment manipulated (a) whether or not the tone to be sung (target) was heard earlier in the melody (primed) and (b) the prime-target distance…

  20. Limited intermixing of synaptic vesicle components upon vesicle recycling.

    PubMed

    Opazo, Felipe; Punge, Annedore; Bückers, Johanna; Hoopmann, Peer; Kastrup, Lars; Hell, Stefan W; Rizzoli, Silvio O

    2010-06-01

    Synaptic vesicles recycle repeatedly in order to maintain synaptic transmission. We have previously proposed that upon exocytosis the vesicle components persist as clusters, which would be endocytosed as whole units. It has also been proposed that the vesicle components diffuse into the plasma membrane and are then randomly gathered into new vesicles. We found here that while strong stimulation (releasing the entire recycling pool) causes the diffusion of the vesicle marker synaptotagmin out of synaptic boutons, moderate stimulation (releasing approximately 19% of all vesicles) is followed by no measurable diffusion. In agreement with this observation, synaptotagmin molecules labeled with different fluorescently tagged antibodies did not appear to mix upon vesicle recycling, when investigated by subdiffraction resolution stimulated emission depletion (STED) microscopy. Finally, as protein diffusion from vesicles has been mainly observed using molecules tagged with pH-sensitive green fluorescent protein (pHluorin), we have also investigated the membrane patterning of several native and pHluorin-tagged proteins. While the native proteins had a clustered distribution, the GFP-tagged ones were diffused in the plasma membrane. We conclude that synaptic vesicle components intermix little, at least under moderate stimulation, possibly because of the formation of clusters in the plasma membrane. We suggest that several pHluorin-tagged vesicle proteins are less well integrated in clusters.

  1. Equilibrium of nematic vesicles

    NASA Astrophysics Data System (ADS)

    Napoli, Gaetano; Vergori, Luigi

    2010-11-01

    A variational scheme is proposed which allows the derivation of a concise and elegant formulation of the equilibrium equations for closed fluid membranes, endowed with a nematic microstructure. The nematic order is described by an in-plane nematic director and a degree of orientation, as customary in the theory of uniaxial nematics. The only constitutive ingredient in this scheme is a free-energy density which depends on the vesicle geometry and order parameters. The stress and the couple stress tensors related to this free-energy density are provided. As an application of the proposed scheme, a certain number of special theories are deduced: soap bubbles, lipid vesicles, chiral and achiral nematic membranes, and nematics on curved substrates.

  2. Poking vesicles in silico

    NASA Astrophysics Data System (ADS)

    Barlow, Ben; Bertrand, Martin; Joos, Bela

    2014-03-01

    The Atomic Force Microscope (AFM) is used to poke cells and study their mechanical properties. Using Coarse-Grained Molecular Dynamics simulations, we study the deformation and relaxation of lipid bilayer vesicles, when poked with a constant force. The relaxation time, equilibrium area expansion, and surface tension of the vesicle membrane are studied over a range of applied forces. The relaxation time exhibits a strong force-dependence. Our force-compression curves show a strong similarity with results from a recent experiment by Schafer et al. (Langmuir, 2013). They used an AFM to ``poke'' adherent giant liposomes with constant nanonewton forces and observed the resulting deformation with a Laser Scanning Confocal Microscope. Results of such experiments, whether on vesicles or cells, are often interpreted in terms of dashpots and springs. This simple approach used to describe the response of a whole cell --complete with cytoskeleton, organelles etc.-- can be problematic when trying to measure the contribution of a single cell component. Our modeling is a first step in a ``bottom-up'' approach where we investigate the viscoelastic properties of an in silico cell prototype with constituents added step by step. Supported by NSERC (Canada).

  3. A Molecular Dynamics Simulation of Vesicle Deformation and Rupture in Confined Poiseuille Flow

    NASA Astrophysics Data System (ADS)

    Harman, Alison

    Vesicles are simple structures, but display complex, non-linear dynamics in fluid flow. I investigate the deformation of nanometer-sized vesicles, both fully-inflated and those with excess area, as they travel in tightly confined capillaries. By varying both channel size and flow strength, I simulate vesicles as they transition from steady-state to unstable shapes, and then rupture in strong flow fields. By employing a molecular dynamics model of the vesicle, fluid, and capillary system one is able to rupture the lipid bilayer of these vesicles. This is unique in that most other numerical methods for modelling vesicles are unable to show rupture. The rupture of fully-inflated vesicles is applicable to drug delivery in which the release of the encapsulated medicine needs to be controlled. The deformation and rupture of vesicles with excess area could be applicable to red blood cells which have similar rheological properties.

  4. Repetition priming in music.

    PubMed

    Hutchins, Sean; Palmer, Caroline

    2008-06-01

    The authors explore priming effects of pitch repetition in music in 3 experiments. Musically untrained participants heard a short melody and sang the last pitch of the melody as quickly as possible. Each experiment manipulated (a) whether or not the tone to be sung (target) was heard earlier in the melody (primed) and (b) the prime-target distance (measured in events). Experiment 1 used variable-length melodies, whereas Experiments 2 and 3 used fixed-length melodies. Experiment 3 changed the timbre of the target tone. In all experiments, fast-responding participants produced repeated tones faster than nonrepeated tones, and this repetition benefit decreased as prime-target distances increased. All participants produced expected tonic endings faster than less expected nontonic endings. Repetition and tonal priming effects are compared with harmonic priming effects in music and with repetition priming effects in language.

  5. Vesicles in Nature and the Laboratory: Elucidation of Their Biological Properties and Synthesis of Increasingly Complex Synthetic Vesicles.

    PubMed

    Fernandez-Trillo, Francisco; Grover, Liam M; Stephenson-Brown, Alex; Harrison, Paul; Mendes, Paula M

    2017-03-13

    The important role of vesicles in many aspects of cell function is well-recognized, but only recently have sophisticated imaging techniques begun to reveal their ubiquity in nature. While we further our understanding of the biological properties of vesicles and their physiological functions, increasingly elegant artificial vesicles are being developed for a wide range of technological applications and basic research. Herein, we examine the state of the art of biological and synthetic vesicles and place their biological features in the context of recent synthetic developments, thus providing a unique overview of these complex and rapidly developing fields. The challenges and opportunities associated with future biological and synthetic studies of vesicles are also presented. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Evaluating the effectiveness of Washington state repeated job search services on the employment rate of prime-age female welfare recipients.

    PubMed

    Hsiao, Cheng; Shen, Yan; Wang, Boqing; Weeks, Greg

    2008-07-01

    This paper uses an unbalanced panel dataset to evaluate how repeated job search services (JSS) and personal characteristics affect the employment rate of the prime-age female welfare recipients in the State of Washington. We propose a transition probability model to take into account issues of sample attrition, sample refreshment and duration dependence. We also generalize Honoré and Kyriazidou's [Honoré, B.E., Kyriazidou, E., 2000. Panel data discrete choice models with lagged dependent variables. Econometrica 68 (4), 839-874] conditional maximum likelihood estimator to allow for the presence of individual-specific effects. A limited information test is suggested to test for selection issues in non-experimental data. The specification tests indicate that the (conditional on the set of the confounding variables considered) assumptions of no selection due to unobservables and/or no unobserved individual-specific effects are not violated. Our findings indicate that the first job search service does have positive and significant impacts on the employment rate. However, providing repeated JSS to the same client has no significant impact. Further, we find that there are significant experience-enhancing effects. These findings suggest that providing one job search services training to individuals may have a lasting impact on raising their employment rates.

  7. 2l-nl{prime} x-ray transitions from neonlike charge states of the row 5 metals with 39 {le} Z {le} 46

    SciTech Connect

    Rice, J.E.; Terry, J.L.; Marmar, E.S.; Fournier, K.B.; Goldstein, W.H.; Finkenthal, M.; Safronova, U.I.

    1996-03-18

    X-ray spectra of 2l-2l{prime} transitions with 3 {le} n {le} 12 in the row five transition metals zirconium (Z = 40), niobium (Z = 41), molybdenum (Z = 42) and palladium (Z = 46) from charge states around neonlike have been observed from Alcator C-Mod plasmas. Accurate wavelengths ({+-} .2 m{angstrom}) have been determined by comparison with neighboring argon, chlorine and sulfur lines with well known wavelengths. Line identifications have been made by comparison to ab initio atomic structure calculations, using a fully relativistic, parametric potential code. For neonlike ions, calculated wavelengths and oscillator strengths are tabulated for 2p-nd transitions in Y (Z = 39), Tc (Z = 43), Ru (Z = 44) and Rh (Z = 45) with n = 6 and 7. The magnitude of the configuration interaction between the (2p{sup 5}){sub 1/2}6d{sub 3/2} J = 1 level and the (2p{sup 5}){sub 3/2}7D{sub 5/2} J = 1 levels is demonstrated as a function of atomic number for successive neonlike ions. Measured spectra of selected transitions in the aluminum-, magnesium-, sodium- and fluorine like isosequences are also shown.

  8. A Well-Defined Readily Releasable Pool with Fixed Capacity for Storing Vesicles at Calyx of Held

    PubMed Central

    Mahfooz, Kashif; Singh, Mahendra; Renden, Robert; Wesseling, John F.

    2016-01-01

    The readily releasable pool (RRP) of vesicles is a core concept in studies of presynaptic function. However, operating principles lack consensus definition and the utility for quantitative analysis has been questioned. Here we confirm that RRPs at calyces of Held from 14 to 21 day old mice have a fixed capacity for storing vesicles that is not modulated by Ca2+. Discrepancies with previous studies are explained by a dynamic flow-through pool, established during heavy use, containing vesicles that are released with low probability despite being immediately releasable. Quantitative analysis ruled out a posteriori explanations for the vesicles with low release probability, such as Ca2+-channel inactivation, and established unexpected boundary conditions for remaining alternatives. Vesicles in the flow-through pool could be incompletely primed, in which case the full sequence of priming steps downstream of recruitment to the RRP would have an average unitary rate of at least 9/s during heavy use. Alternatively, vesicles with low and high release probability could be recruited to distinct types of release sites; in this case the timing of recruitment would be similar at the two types, and the downstream transition from recruited to fully primed would be much faster. In either case, further analysis showed that activity accelerates the upstream step where vesicles are initially recruited to the RRP. Overall, our results show that the RRP can be well defined in the mathematical sense, and support the concept that the defining mechanism is a stable group of autonomous release sites. PMID:27035349

  9. A Well-Defined Readily Releasable Pool with Fixed Capacity for Storing Vesicles at Calyx of Held.

    PubMed

    Mahfooz, Kashif; Singh, Mahendra; Renden, Robert; Wesseling, John F

    2016-04-01

    The readily releasable pool (RRP) of vesicles is a core concept in studies of presynaptic function. However, operating principles lack consensus definition and the utility for quantitative analysis has been questioned. Here we confirm that RRPs at calyces of Held from 14 to 21 day old mice have a fixed capacity for storing vesicles that is not modulated by Ca2+. Discrepancies with previous studies are explained by a dynamic flow-through pool, established during heavy use, containing vesicles that are released with low probability despite being immediately releasable. Quantitative analysis ruled out a posteriori explanations for the vesicles with low release probability, such as Ca2+-channel inactivation, and established unexpected boundary conditions for remaining alternatives. Vesicles in the flow-through pool could be incompletely primed, in which case the full sequence of priming steps downstream of recruitment to the RRP would have an average unitary rate of at least 9/s during heavy use. Alternatively, vesicles with low and high release probability could be recruited to distinct types of release sites; in this case the timing of recruitment would be similar at the two types, and the downstream transition from recruited to fully primed would be much faster. In either case, further analysis showed that activity accelerates the upstream step where vesicles are initially recruited to the RRP. Overall, our results show that the RRP can be well defined in the mathematical sense, and support the concept that the defining mechanism is a stable group of autonomous release sites.

  10. The Development of Steady-State Activation Hubs between Adult LTi ILC3s and Primed Macrophages in Small Intestine.

    PubMed

    Savage, Adam K; Liang, Hong-Erh; Locksley, Richard M

    2017-09-01

    Group 3 innate lymphoid cells (ILC3s) are important for intestinal health, particularly in controlling inflammation in response to epithelial dysregulation, but their role during homeostasis remains less well understood. We generated IL-22 reporter mice to assess production of this key cytokine by ILC3s in the small intestine during development and under basal conditions. Although IL-22 is produced by a variety of lymphocyte populations, constitutively high IL-22 expression was limited to lymphoid-tissue inducer (LTi) cells residing in lymph node-like structures in the gut called solitary intestinal lymphoid tissues (SILT). Constitutive IL-22 expression was dependent on the microbiota and MyD88 signaling, appeared upon weaning, and was present across the spectrum of SILT, including in cryptopatches. Activated SILT LTi cells colocalized with a rare subpopulation of activated macrophages constitutively positive for IL-12/23 p40 and capable of activating neonatal LTi cells in response to TLR stimulus. Thus, weaning leads to the organization of innate immune activation hubs at SILT that mature and are continuously sustained by signals from the microbiota. This functional and anatomic organization constitutes a significant portion of the steady-state IL-23/IL-22 axis. Copyright © 2017 by The American Association of Immunologists, Inc.

  11. Unconventional molecular regulation of synaptic vesicle replenishment in cochlear inner hair cells.

    PubMed

    Vogl, Christian; Cooper, Benjamin H; Neef, Jakob; Wojcik, Sonja M; Reim, Kerstin; Reisinger, Ellen; Brose, Nils; Rhee, Jeong-Seop; Moser, Tobias; Wichmann, Carolin

    2015-02-15

    Ribbon synapses of cochlear inner hair cells (IHCs) employ efficient vesicle replenishment to indefatigably encode sound. In neurons, neuroendocrine and immune cells, vesicle replenishment depends on proteins of the mammalian uncoordinated 13 (Munc13, also known as Unc13) and Ca(2+)-dependent activator proteins for secretion (CAPS) families, which prime vesicles for exocytosis. Here, we tested whether Munc13 and CAPS proteins also regulate exocytosis in mouse IHCs by combining immunohistochemistry with auditory systems physiology and IHC patch-clamp recordings of exocytosis in mice lacking Munc13 and CAPS isoforms. Surprisingly, we did not detect Munc13 or CAPS proteins at IHC presynaptic active zones and found normal IHC exocytosis as well as auditory brainstem responses (ABRs) in Munc13 and CAPS deletion mutants. Instead, we show that otoferlin, a C2-domain protein that is crucial for vesicular fusion and replenishment in IHCs, clusters at the plasma membrane of the presynaptic active zone. Electron tomography of otoferlin-deficient IHC synapses revealed a reduction of short tethers holding vesicles at the active zone, which might be a structural correlate of impaired vesicle priming in otoferlin-deficient IHCs. We conclude that IHCs use an unconventional priming machinery that involves otoferlin.

  12. Shapes of Mixed Phospholipid Vesicles

    PubMed Central

    Aranda-Espinoza, Helim; Maldonado, Amir

    2006-01-01

    We studied the shape of phospholipid vesicles prepared by hydration of a mixture of phosphatidylcholine (SOPC) and phosphatidylserine (SOPS) in different proportions. The aim of the work is to obtain some insight into the influence of the chemical composition of a biomembrane on its shape. The optical microscopy results show that the shape of the vesicles depend on the SOPC:SOPS composition. For low SOPS contents, coiled cylindrical vesicles are observed. The results suggest that specific compositions of the SOPC:SOPS vesicles produce some spontaneous curvature on the membrane and then a coiling instability. PMID:19669461

  13. Characterization of extracellular vesicles in whole blood: Influence of pre-analytical parameters and visualization of vesicle-cell interactions using imaging flow cytometry.

    PubMed

    Fendl, Birgit; Weiss, René; Fischer, Michael B; Spittler, Andreas; Weber, Viktoria

    2016-09-09

    Extracellular vesicles are central players in intercellular communication and are released from the plasma membrane under tightly regulated conditions, depending on the physiological and pathophysiological state of the producing cell. Their heterogeneity requires a spectrum of methods for isolation and characterization, where pre-analytical parameters have profound impact on vesicle analysis, particularly in blood, since sampling, addition of anticoagulants, as well as post-sampling vesicle generation may influence the outcome. Here, we characterized microvesicles directly in whole blood using a combination of flow cytometry and imaging flow cytometry. We assessed the influence of sample agitation, anticoagulation, and temperature on post-sampling vesicle generation, and show that vesicle counts remained stable over time in samples stored without agitation. Storage with gentle rolling mimicking agitation, in contrast, resulted in strong release of platelet-derived vesicles in blood anticoagulated with citrate or heparin, whereas vesicle counts remained stable upon anticoagulation with EDTA. Using imaging flow cytometry, we could visualize microvesicles adhering to blood cells and revealed an anticoagulant-dependent increase in vesicle-cell aggregates over time. We demonstrate that vesicles adhere preferentially to monocytes and granulocytes in whole blood, while no microvesicles could be visualized on lymphocytes. Our data underscore the relevance of pre-analytical parameters in vesicle analysis and demonstrate that imaging flow cytometry is a suitable tool to study the interaction of extracellular vesicles with their target cells.

  14. Loss of CMAH during Human Evolution Primed the Monocyte-Macrophage Lineage toward a More Inflammatory and Phagocytic State.

    PubMed

    Okerblom, Jonathan J; Schwarz, Flavio; Olson, Josh; Fletes, William; Ali, Syed Raza; Martin, Paul T; Glass, Christopher K; Nizet, Victor; Varki, Ajit

    2017-03-15

    Humans and chimpanzees are more sensitive to endotoxin than are mice or monkeys, but any underlying differences in inflammatory physiology have not been fully described or understood. We studied innate immune responses in Cmah(-/-) mice, emulating human loss of the gene encoding production of Neu5Gc, a major cell surface sialic acid. CMP-N-acetylneuraminic acid hydroxylase (CMAH) loss occurred ∼2-3 million years ago, after the common ancestor of humans and chimpanzees, perhaps contributing to speciation of the genus HomoCmah(-/-) mice manifested a decreased survival in endotoxemia following bacterial LPS injection. Macrophages from Cmah(-/-) mice secreted more inflammatory cytokines with LPS stimulation and showed more phagocytic activity. Macrophages and whole blood from Cmah(-/-) mice also killed bacteria more effectively. Metabolic reintroduction of Neu5Gc into Cmah(-/-) macrophages suppressed these differences. Cmah(-/-) mice also showed enhanced bacterial clearance during sublethal lung infection. Although monocytes and monocyte-derived macrophages from humans and chimpanzees exhibited marginal differences in LPS responses, human monocyte-derived macrophages killed Escherichia coli and ingested E. coli BioParticles better. Metabolic reintroduction of Neu5Gc into human macrophages suppressed these differences. Although multiple mechanisms are likely involved, one cause is altered expression of C/EBPβ, a transcription factor affecting macrophage function. Loss of Neu5Gc in Homo likely had complex effects on immunity, providing greater capabilities to clear sublethal bacterial challenges, possibly at the cost of endotoxic shock risk. This trade-off may have provided a selective advantage when Homo transitioned to butchery using stone tools. The findings may also explain why the Cmah(-/-) state alters severity in mouse models of human disease. Copyright © 2017 by The American Association of Immunologists, Inc.

  15. Dihydrolipoyl dioleoylglycerol antioxidant capacity in phospholipid vesicles.

    PubMed

    Laszlo, Joseph A; Evans, Kervin O; Compton, David L; Appell, Michael

    2012-02-01

    Antioxidants have critical roles in maintaining cellular homeostasis and disease-state prevention. The multi-functional agent α-lipoic acid offers numerous beneficial effects to oxidatively stressed tissues. α-Lipoic acid was enzymatically incorporated into a triglyceride in conjunction with oleic acid, creating lipoyl dioleoylglycerol, and chemically reduced to form dihydrolipoyl dioleoylglycerol. The triglyceride forms of lipoic acid stabilized dioleoylphosphatidylcholine unilamellar liposomal vesicles, as judged by calcein-cobalt leakage. Stabilization resulted from increased packing density of phospholipid acyl chains. Scavenging activity against the 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) radical was monitored by oxidation of 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid (C(11)-Bodipy). Dihydrolipoyl dioleoylglycerol in vesicles demonstrated strong antioxidant capacity in comparison to the conventional Trolox standard. Fluorescence quenching measurements indicated the lipoyl moiety of dihydrolipoyl dioleoylglycerol is positioned near the vesicle aqueous/lipid boundary. Treatment of intact vesicles with a nonpenetrating sulfhydryl reagent indicated that 80% of the dihydrolipoyl dioleoylglycerol was available for reaction. Molecular modeling of lipoyl dioleoylglycerol and dihydrolipoyl dioleoylglycerol in a phospholipid layer confirmed the existence of an extended configuration for the molecules that accounts for the interfacial location of the lipoyl moiety, which may allow the antioxidant to readily react with radical species approaching membranes from the aqueous phase. Published by Elsevier Ireland Ltd.

  16. An ERP investigation of orthographic priming with superset primes.

    PubMed

    Ktori, Maria; Midgley, Katherine; Holcomb, Phillip J; Grainger, Jonathan

    2015-01-12

    Prime stimuli formed by inserting unrelated letters in a given target word (called "superset" primes) provide a means to modify the relative positions of the letters shared by prime and target. Here we examined the time-course of superset priming effects in an ERP study using the sandwich-priming paradigm. We compared the effects of superset primes formed by the insertion of unrelated letters (e.g., maurkdet-MARKET), or by the insertion of hyphens (e.g., ma-rk-et-MARKET), with identity priming (e.g., market-MARKET), all measured relative to unrelated control primes. Behavioral data revealed significantly greater priming in the hyphen-insert condition compared with the letter-insert condition. In the ERP signal, letter-insert priming emerged later than hyphen-insert priming and produced a reversed priming effect in the N400 time-window compared with the more typical N400 priming effects seen for both hyphen-insert priming and identity priming. The different pattern of priming effects seen for letter-insert primes and hyphen-insert primes suggests that compared with identity priming, letter superset priming reflects the joint influence of: (1) a disruption in letter position information, and (2) an inhibitory influence of mismatching letters.

  17. Identification of a Munc13-sensitive step in chromaffin cell large dense-core vesicle exocytosis

    PubMed Central

    Man, Kwun Nok M; Imig, Cordelia; Walter, Alexander M; Pinheiro, Paulo S; Stevens, David R; Rettig, Jens; Sørensen, Jakob B; Cooper, Benjamin H; Brose, Nils; Wojcik, Sonja M

    2015-01-01

    It is currently unknown whether the molecular steps of large dense-core vesicle (LDCV) docking and priming are identical to the corresponding reactions in synaptic vesicle (SV) exocytosis. Munc13s are essential for SV docking and priming, and we systematically analyzed their role in LDCV exocytosis using chromaffin cells lacking individual isoforms. We show that particularly Munc13-2 plays a fundamental role in LDCV exocytosis, but in contrast to synapses lacking Munc13s, the corresponding chromaffin cells do not exhibit a vesicle docking defect. We further demonstrate that ubMunc13-2 and Munc13-1 confer Ca2+-dependent LDCV priming with similar affinities, but distinct kinetics. Using a mathematical model, we identify an early LDCV priming step that is strongly dependent upon Munc13s. Our data demonstrate that the molecular steps of SV and LDCV priming are very similar while SV and LDCV docking mechanisms are distinct. DOI: http://dx.doi.org/10.7554/eLife.10635.001 PMID:26575293

  18. Vesicles with a double bilayer.

    PubMed

    Zawada, Zygmunt H

    2004-01-01

    A modified reverse phase evaporation method was used to prepare intermediate unilamellar vesicles coated with an additional membrane, or large vesicles in which several vesicles were coated with a common membrane. In both kinds of vesicle, the outer and inner membranes are usually of different phospholipid composition. The preparation involves the formation of a double emulsion: vesicles in a buffer are emerged in a low-boiling point organic solution of phospholipids. Then the organic solvent is evaporated during the heating and mixing process. As result large unilamellar vesicles (LUVs), about 100 nm in diameter, were coated with an additional membrane from egg lecithin or dipalmitoylphosphatidylcholine and cholesterol. The highest yield of the coating was about 50%. When DPPC was used for coating above the phase transition temperature Tm, the data suggested the formation of vesicles that were slightly larger than the starting LUVs. It might be concluded that many of these had a double bilayer. If the coating was done below Tm, the micrographs suggested the formation of structures resembling multi-vesicular vesicles. They looked like LUV clusters coated with a common membrane.

  19. Reversible Recruitment of a Homeostatic Reserve Pool of Synaptic Vesicles Underlies Rapid Homeostatic Plasticity of Quantal Content

    PubMed Central

    Pinter, Martin J.; Rich, Mark M.

    2016-01-01

    priming/docking of a small homeostatic reserve pool of vesicles that normally have slow-release kinetics. Following priming, the reserve pool of vesicles is released synchronously with the normal readily releasable pool of synaptic vesicles. This is the first description of this unique pool of synaptic vesicles. PMID:26791213

  20. Hydrodynamic interactions between two vesicles

    NASA Astrophysics Data System (ADS)

    Gires, Pierre-Yves; Dyfcom Team

    2011-11-01

    A giant vesicle is a closed elastic membrane containing a liquid, inside another liquid. Its size is around 10 microns. If a suspension of such objects is sheared, they sometimes come close and interact hydrodynamically. We studied how these interactions affect the trajectories of the vesicles. For this, we model the properties of the membrane, assuming that the area of a surface element is constant in the course of time, and that it resists bending. We also assume that the inside and outside fluids are Newtonian, and are in the creeping regime. To solve the partial differential equations arising from this model, we used two methods : an asymptotic expansion around spherical shapes for vesicles far away from each other (3d case), and a boudary integral method (2d case). We find that vesicles repel, and that this repulsion decreases with initial transverse distance. We compare our results with experimental results performed with vesicles flowing in microfluidic devices.

  1. Molecular recognition of bilayer vesicles.

    PubMed

    Voskuhl, Jens; Ravoo, Bart Jan

    2009-02-01

    Vesicles have been a versatile topic of research in chemistry ever since the discovery that, besides phospholipids, synthetic amphiphiles can also form molecular bilayers enclosing a small aqueous compartment. Non-covalent interactions of receptors and ligands or hosts and guests at vesicle surfaces resemble recognition processes at biological membranes, including cell recognition, adhesion and fusion. Molecular recognition at membranes is often mediated by a multivalent instead of a monovalent interaction. This tutorial review describes the basics as well as the latest developments in biomimetic supramolecular chemistry of bilayer vesicles. We describe how molecular recognition can mediate the interaction between vesicles, and how the biomimetic supramolecular chemistry of vesicles furthers our understanding of biological membranes.

  2. Stabilization and swelling of hagfish slime mucin vesicles.

    PubMed

    Herr, J E; Winegard, T M; O'Donnell, M J; Yancey, P H; Fudge, D S

    2010-04-01

    When agitated, Atlantic hagfish (Myxine glutinosa) produce large quantities of slime that consists of hydrated bundles of protein filaments and membrane-bound mucin vesicles from numerous slime glands. When the slime exudate contacts seawater, the thread bundles unravel and the mucin vesicles swell and rupture. Little is known about the mechanisms of vesicle rupture in seawater and stabilization within the gland, although it is believed that the vesicle membrane is permeable to most ions except polyvalent anions. We hypothesized that the most abundant compounds within the slime gland exudate have a stabilizing effect on the mucin vesicles. To test this hypothesis, we measured the chemical composition of the fluid component of hagfish slime exudate and conducted functional assays with these solutes to test their ability to keep the vesicles in a condensed state. We found K(+) concentrations that were elevated relative to plasma, and Na(+), Cl(-) and Ca(2+) concentrations that were considerably lower. Our analysis also revealed high levels of methylamines such as trimethylamine oxide (TMAO), betaine and dimethylglycine, which had a combined concentration of 388 mmol l(-1) in the glandular fluid. In vitro rupture assays demonstrated that both TMAO and betaine had a significant effect on rupture, but neither was capable of completely abolishing mucin swelling and rupture, even at high concentrations. This suggests that some other mechanism such as the chemical microenvironment within gland mucous cells, or hydrostatic pressure is responsible for stabilization of the vesicles within the gland.

  3. The dynamics of adhesion of a pair of vesicles

    NASA Astrophysics Data System (ADS)

    Walter, Johann; Leal, L. Gary

    2012-11-01

    Adhesive interactions within a suspension of vesicles, such as many personal care products, vectors for drug delivery or artificial blood, can lead to aggregation of the vesicles and dramatic changes to the properties of the suspension. We study the adhesion of a pair of unilamellar, charged vesicles under flow, in the presence of a non-adsorbing polymer or micelle creating a depletion attraction force between the vesicles. Simulations are conducted using a numerical model coupling the boundary integral method for the motion of the fluids and a finite element method for the membrane mechanics (resistance to bending and area increase are both taken into account). The dynamics of the drainage process are studied. At steady state, the adhesion energy is found to depend greatly on the ability of the vesicles to increase their surface area. Finally, when the vesicles are separated in an elongational flow, different behaviors are observed depending on the deformability of the vesicles: an increase of the film thickness with a constant contact area, or peeling-off phenomenon where the contact area decreases at constant film thickness.

  4. Inactivation of the ribonucleoside triphosphate reductase from Lactobacillus leichmannii by 2 prime -chloro-2 prime -deoxyuridine 5 prime -triphosphate: A 3 prime -2 prime hydrogen transfer during the formation of 3 prime -keto-2 prime -deoxyuridine 5 prime -triphosphate

    SciTech Connect

    Ashley, G.W.; Harris, G.; Stubbe, J. )

    1988-10-04

    The ribonucleoside triphosphate reductase of Lactobacillus leichmannii converts the substrate analogue 2{prime}-chloro-2{prime}-deoxyuridine 5{prime}-triphosphate (C1UTP) into a mixture of 2{prime}-deoxyuridine triphosphate (dUTP) and the unstable product 3{prime}-keto-2{prime}-deoxyuridine triphosphate (3{prime}-keto-dUTP). This ketone can be trapped by reduction with NaBH{sub 4}, producing a 4:1 mixture of xylo-dUTP and dUTP. When (3{prime}-{sup 3}H)C1UTP is treated with enzyme in the presence of NaBH{sub 4}, the isomeric deoxyuridines isolated after alkaline phosphatase treatment retained 15% of the {sup 3}H in C1UTP. Degradation of these isomeric nucleosides has established the location of the {sup 3}H in 3{prime}-keto-dUTP as predominantly 2{prime}(S). The xylo-dU had 98.6% of its label at the 2{prime}(S) position and 1.5% at 2{prime}(R). The isolated dU had 89.6% of its label at 2{prime}(S) and 1.4% at 2{prime}(R), with the remaining 9% label inferred to be at the 3{prime}-carbon, this resulting from the direct enzymic production of dUTP. These results are consistent with enzymic production of a 1:1,000 mixture of dUTP and 3{prime}-keto-dUTP, where the 3{prime}-hydrogen of C1UTP is retained at 3{prime} during production of dUTP and is transferred to 2{prime}(S) during production of 3{prime}-keto-dUTP. The implications of these results and the unique role of the cofactor adenosylcobalamin are discussed in terms of reductase being a model for the B{sub 12}-dependent rearrangement reactions.

  5. Asymptotic prime partitions of integers

    NASA Astrophysics Data System (ADS)

    Bartel, Johann; Bhaduri, R. K.; Brack, Matthias; Murthy, M. V. N.

    2017-05-01

    In this paper, we discuss P (n ) , the number of ways a given integer n may be written as a sum of primes. In particular, an asymptotic form Pas(n ) valid for n →∞ is obtained analytically using standard techniques of quantum statistical mechanics. First, the bosonic partition function of primes, or the generating function of unrestricted prime partitions in number theory, is constructed. Next, the density of states is obtained using the saddle-point method for Laplace inversion of the partition function in the limit of large n . This gives directly the asymptotic number of prime partitions Pas(n ) . The leading term in the asymptotic expression grows exponentially as √{n /ln(n ) } and agrees with previous estimates. We calculate the next-to-leading-order term in the exponent, proportional to ln[ln(n )]/ln(n ) , and we show that an earlier result in the literature for its coefficient is incorrect. Furthermore, we also calculate the next higher-order correction, proportional to 1 /ln(n ) and given in Eq. (43), which so far has not been available in the literature. Finally, we compare our analytical results with the exact numerical values of P (n ) up to n ˜8 ×106 . For the highest values, the remaining error between the exact P (n ) and our Pas(n ) is only about half of that obtained with the leading-order approximation. But we also show that, unlike for other types of partitions, the asymptotic limit for the prime partitions is still quite far from being reached even for n ˜107 .

  6. Building Numbers from Primes

    ERIC Educational Resources Information Center

    Burkhart, Jerry

    2009-01-01

    Prime numbers are often described as the "building blocks" of natural numbers. This article shows how the author and his students took this idea literally by using prime factorizations to build numbers with blocks. In this activity, students explore many concepts of number theory, including the relationship between greatest common factors and…

  7. Priming Ability Emotional Intelligence

    ERIC Educational Resources Information Center

    Schutte, Nicola S.; Malouff, John M.

    2012-01-01

    Two studies examined whether priming self-schemas relating to successful emotional competency results in better emotional intelligence performance. In the first study participants were randomly assigned to a successful emotional competency self-schema prime condition or a control condition and then completed an ability measure of emotional…

  8. PRIME Lab Radiocarbon Measurements

    NASA Astrophysics Data System (ADS)

    Hillegonds, D. J.; Mueller, K. A.; Ma, X.; Lipschutz, M. E.

    1996-03-01

    The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is one of three NSF national facilities for accelerator mass spectrometry (AMS), and is the only one capable of determining six cosmogenic radionuclides: 10Be, 14C, 26Al, 36Cl, 41Ca, and 129I. This abstract describes the current status of the radiocarbon analysis program at PRIME Lab.

  9. Discovery: Prime Numbers

    ERIC Educational Resources Information Center

    de Mestre, Neville

    2008-01-01

    Prime numbers are important as the building blocks for the set of all natural numbers, because prime factorisation is an important and useful property of all natural numbers. Students can discover them by using the method known as the Sieve of Eratosthenes, named after the Greek geographer and astronomer who lived from c. 276-194 BC. Eratosthenes…

  10. Recognizing Plant Defense Priming.

    PubMed

    Martinez-Medina, Ainhoa; Flors, Victor; Heil, Martin; Mauch-Mani, Brigitte; Pieterse, Corné M J; Pozo, Maria J; Ton, Jurriaan; van Dam, Nicole M; Conrath, Uwe

    2016-10-01

    Defense priming conditions diverse plant species for the superinduction of defense, often resulting in enhanced pest and disease resistance and abiotic stress tolerance. Here, we propose a guideline that might assist the plant research community in a consistent assessment of defense priming in plants.

  11. Priming Ability Emotional Intelligence

    ERIC Educational Resources Information Center

    Schutte, Nicola S.; Malouff, John M.

    2012-01-01

    Two studies examined whether priming self-schemas relating to successful emotional competency results in better emotional intelligence performance. In the first study participants were randomly assigned to a successful emotional competency self-schema prime condition or a control condition and then completed an ability measure of emotional…

  12. A new Mersenne prime

    NASA Astrophysics Data System (ADS)

    Colquitt, W. N.; Welsh, L.

    1991-04-01

    The number {2^{110503}} - 1 is a Mersenne prime. There are exactly two Mersenne exponents between 100000 and 139268, and there are no Mersenne exponents between 216092 and 353620. Thus, the number {2^{132049}} - 1 has been verified as the 30th Mersenne prime in order of size.

  13. Building Numbers from Primes

    ERIC Educational Resources Information Center

    Burkhart, Jerry

    2009-01-01

    Prime numbers are often described as the "building blocks" of natural numbers. This article shows how the author and his students took this idea literally by using prime factorizations to build numbers with blocks. In this activity, students explore many concepts of number theory, including the relationship between greatest common factors and…

  14. Priming Gestures with Sounds

    PubMed Central

    Lemaitre, Guillaume; Heller, Laurie M.; Navolio, Nicole; Zúñiga-Peñaranda, Nicolas

    2015-01-01

    We report a series of experiments about a little-studied type of compatibility effect between a stimulus and a response: the priming of manual gestures via sounds associated with these gestures. The goal was to investigate the plasticity of the gesture-sound associations mediating this type of priming. Five experiments used a primed choice-reaction task. Participants were cued by a stimulus to perform response gestures that produced response sounds; those sounds were also used as primes before the response cues. We compared arbitrary associations between gestures and sounds (key lifts and pure tones) created during the experiment (i.e. no pre-existing knowledge) with ecological associations corresponding to the structure of the world (tapping gestures and sounds, scraping gestures and sounds) learned through the entire life of the participant (thus existing prior to the experiment). Two results were found. First, the priming effect exists for ecological as well as arbitrary associations between gestures and sounds. Second, the priming effect is greatly reduced for ecologically existing associations and is eliminated for arbitrary associations when the response gesture stops producing the associated sounds. These results provide evidence that auditory-motor priming is mainly created by rapid learning of the association between sounds and the gestures that produce them. Auditory-motor priming is therefore mediated by short-term associations between gestures and sounds that can be readily reconfigured regardless of prior knowledge. PMID:26544884

  15. Activation of metabotropic GABA receptors increases the energy barrier for vesicle fusion.

    PubMed

    Rost, Benjamin R; Nicholson, Patrick; Ahnert-Hilger, Gudrun; Rummel, Andreas; Rosenmund, Christian; Breustedt, Joerg; Schmitz, Dietmar

    2011-09-15

    Neurotransmitter release from presynaptic terminals is under the tight control of various metabotropic receptors. We report here that in addition to the regulation of Ca(2+) channel activity, metabotropic GABA(B) receptors (GABA(B)Rs) at murine hippocampal glutamatergic synapses utilize an inhibitory pathway that directly targets the synaptic vesicle release machinery. Acute application of the GABA(B)R agonist baclofen rapidly and reversibly inhibits vesicle fusion, which occurs independently of the SNAP-25 C-terminus. Using applications of hypertonic sucrose solutions, we find that the size of the readily releasable pool remains unchanged by GABA(B)R activation, but the sensitivity of primed vesicles to hypertonic stimuli appears lowered as the response amplitudes at intermediate sucrose concentrations are smaller and release kinetics are slowed. These data show that presynaptic GABA(B)Rs can inhibit neurotransmitter release directly by increasing the energy barrier for vesicle fusion.

  16. Microfluidic isolation of cancer-cell-derived microvesicles from hetergeneous extracellular shed vesicle populations

    PubMed Central

    Santana, Steven M.; Antonyak, Marc A.; Cerione, Richard A.

    2015-01-01

    Extracellular shed vesicles, including exosomes and microvesicles, are disseminated throughout the body and represent an important conduit of cell communication. Cancer-cell-derived microvesicles have potential as a cancer biomarker as they help shape the tumor microenvironment to promote the growth of the primary tumor and prime the metastatic niche. It is likely that, in cancer cell cultures, the two constituent extracellular shed vesicle subpopulations, observed in dynamic light scattering, represent an exosome population and a cancer-cell-specific microvesicle population and that extracellular shed vesicle size provides information about provenance and cargo. We have designed and implemented a novel microfluidic technology that separates microvesicles, as a function of diameter, from heterogeneous populations of cancer-cell-derived extracellular shed vesicles. We measured cargo carried by the microvesicle subpopulation processed through this microfluidic platform. Such analyses could enable future investigations to more accurately and reliably determine provenance, functional activity, and mechanisms of transformation in cancer. PMID:25342569

  17. Adsorption and encapsulation of flexible polyelectrolytes in charged spherical vesicles

    NASA Astrophysics Data System (ADS)

    Shojaei, H. R.; Muthukumar, M.

    2017-06-01

    We present a theory of adsorption of flexible polyelectrolytes on the interior and exterior surfaces of a charged vesicle in an electrolyte solution. The criteria for adsorption and the density profiles of the adsorbed polymer chain are derived in terms of various characteristics of the polymer, vesicle, and medium, such as the charge density and length of the polymer, charge density and size of the vesicle, electrolyte concentration and dielectric constant of the medium. For adsorption inside the vesicle, the competition between the loss of conformational entropy and gain in adsorption energy results in two kinds of encapsulated states, depending on the strength of the polymer-vesicle interaction. By considering also the adsorption from outside the vesicle, we derive the entropic and energy contributions to the free energy change to transfer an adsorbed chain in the interior to an adsorbed chain on the exterior. In this paper, we have used the Wentzel-Kramers-Brillouin (WKB) method to solve the equation for the probability distribution function of the chain. The present WKB results are compared with the previous results based on variational methods. The WKB and variational results are in good agreement for both the interior and exterior states of adsorption, except in the zero-salt limit for adsorption in the exterior region. The adsorption criteria and density profiles for both the interior and exterior states are presented in terms of various experimentally controllable variables. Calculation of the dependencies of free energy change to transfer an adsorbed chain from the interior to the exterior surface on salt concentration and vesicle radius shows that the free energy penalty to expel a chain from a vesicle is only of the order of thermal energy.

  18. Membrane Transport in Isolated Vesicles from Sugarbeet Taproot 1

    PubMed Central

    Briskin, Donald P.; Thornley, W. Robert; Wyse, Roger E.

    1985-01-01

    Sealed membrane vesicles were isolated from homogenates of sugarbeet (Beta vulgaris L.) taproot by a combination of differential centrifugation, extraction with KI, and dextran gradient centrifugation. Relative to the KI-extracted microsomes, the content of plasma membranes, mitochondrial membranes, and Golgi membranes was much reduced in the final vesicle fraction. A component of ATPase activity that was inhibited by nitrate co-enriched with the capacity of the vesicles to form a steady state pH gradient during the purification procedure. This suggests that the nitrate-sensitive ATPase may be involved in driving H+-transport, and this is consistent with the observation that H+-transport, in the final vesicle fraction was inhibited by nitrate. Proton transport in the sugarbeet vesicles was substrate specific for ATP, insensitive to sodium vanadate and oligomycin but was inhibited by diethylstilbestrol and N,N′-dicyclohexylcarbodiimide. The formation of a pH gradient in the vesicles was enhanced by halide ions in the sequence I− > Br− > Cl− while F− was inhibitory. These stimulatory effects occur from both a direct stimulation of the ATPase by anions and a reduction in the vesicle membrane potential. In the presence of Cl−, alkali cations reduce the pH gradient relative to that observed with bis-tris-propane, possibly by H+/alkali cation exchange. Based upon the properties of the H+-transporting vesicles, it is proposed that they are most likely derived from the tonoplast so that this vesicle preparation would represent a convenient system for studying the mechanism of transport at this membrane boundary. PMID:16664342

  19. Mass spectrometry of extracellular vesicles.

    PubMed

    Pocsfalvi, Gabriella; Stanly, Christopher; Vilasi, Annalisa; Fiume, Immacolata; Capasso, Giovambattista; Turiák, Lilla; Buzas, Edit I; Vékey, Károly

    2016-01-01

    The review briefly summaries main features of extracellular vesicles, a joint terminology for exosomes, microvesicles, and apoptotic vesicles. These vesicles are in the center of interest in biology and medical sciences, and form a very active field of research. Mass spectrometry (MS), with its specificity and sensitivity, has the potential to identify and characterize molecular composition of these vesicles; but as yet there are only a limited, but fast-growing, number of publications that use MS workflows in this field. MS is the major tool to assess protein composition of extracellular vesicles: qualitative and quantitative proteomics approaches are both reviewed. Beside proteins, lipid and metabolite composition of vesicles might also be best assessed by MS techniques; however there are few applications as yet in this respect. The role of alternative analytical approaches, like gel-based proteomics and antibody-based immunoassays, are also mentioned. The objective of the review is to give an overview of this fast-growing field to help orient MS-based research on extracellular vesicles. © 2015 Wiley Periodicals, Inc.

  20. Prime Time in the First Grade at the North Gibson School Corporation: The First Four Years. A Longitudinal Evaluation of Indiana's State-Supported Reduced Class Size Program.

    ERIC Educational Resources Information Center

    Gilman, David A.

    The purpose of this study was to investigate the impact of reducing the size of first grade classes on students' achievement. Four groups of first grade students who had participated in Indiana's Project PRIME TIME (average class size of l8 or fewer) for 1 year were compared to one class of first grade students who had received first grade…

  1. Melting transition in lipid vesicles functionalised by mobile DNA linkers.

    PubMed

    Bachmann, Stephan Jan; Kotar, Jurij; Parolini, Lucia; Šarić, Anđela; Cicuta, Pietro; Di Michele, Lorenzo; Mognetti, Bortolo Matteo

    2016-09-20

    We study phase behaviour of lipid-bilayer vesicles functionalised by ligand-receptor complexes made of synthetic DNA by introducing a modelling framework and a dedicated experimental platform. In particular, we perform Monte Carlo simulations that combine a coarse grained description of the lipid bilayer with state of art analytical models for multivalent ligand-receptor interactions. Using density of state calculations, we derive the partition function in pairs of vesicles and compute the number of ligand-receptor bonds as a function of temperature. Numerical results are compared to microscopy and fluorimetry experiments on large unilamellar vesicles decorated by DNA linkers carrying complementary overhangs. We find that vesicle aggregation is suppressed when the total number of linkers falls below a threshold value. Within the model proposed here, this is due to the higher configurational costs required to form inter-vesicle bridges as compared to intra-vesicle loops, which are in turn related to membrane deformability. Our findings and our numerical/experimental methodologies are applicable to the rational design of liposomes used as functional materials and drug delivery applications, as well as to study inter-membrane interactions in living systems, such as cell adhesion.

  2. Spectroscopic and photophysical properties of complexes of 4{prime}-ferrocenyl-2,2{prime}:6{prime},2{double_prime}-terpyridine and related ligands

    SciTech Connect

    Hutchinson, K.; Morris, J.C.; Nile, T.A.; Walsh, J.L.; Thompson, D.W.; Petersen, J.D.; Schoonover, J.R.

    1999-05-17

    4{prime}-(Ferrocenyl)-2,2{prime}:6{prime}2{double_prime}-terpyridine (Fctpy) and 4{prime}-(4-pyridyl)-2,2{prime}:6{prime},2{double_prime}-terpyridine (pytpy) were prepared from the corresponding ferrocene- and pyridinecarboxaldehyle and 2-acetylpyridine using the Krohnke synthetic methodology. Metal complexes, [M(Fctpy){sub 2}](PF{sub 6}){sub 2} (M = Ru, Fe, Zn), [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2} (tpy = 2,2{prime}:6{prime},6{double_prime}-terpyridine), and [Ru(pytpy){sub 2}](PF{sub 6}){sub 2} were prepared and characterized. Cyclic voltammetric analysis indicated Ru(III/II) and ferrocenium/ferrocene redox couples near expected potentials (Ru{sup III/II} {approximately}1.3 V and ferrocenium/ferrocene {approximately}0.6 V vs Ag/AgCl). In addition to dominant {pi}{sub tpy} {r_arrow} {pi}{sub tpy}{sup *} UV absorptions near 240 and 280 nm and d{sub {pi}}{sup Ru} {r_arrow} {pi}{sub tpy}{sup *} MLCT absorptions around 480 nm, the complexes [Ru(Fctpy){sub 2}](PF{sub 6}){sub 2} and [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2} exhibit an unusual absorption band around 530 nm. Resonance Raman measurements indicate that this band is due to a {sup 1}[(d({pi}){sub Fc}){sup 6}] {r_arrow} {sup 1}[(d({pi}){sub Fc}){sup 5}({pi}{sup *}{sub tpy}{sup Ru}){sup 1}] transition. For [Ru(Fctpy){sub 2}](PF{sub 6}){sub 2} and [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2}, excited-state emission and lifetime measurements indicated an upper-limit emission quantum yield of 0.003 and an upper-limit emission lifetime of 0.025 {micro}s. The influence of the ferrocenyl site on excited-state decay is discussed, and an excited-state energy level diagram is proposed.

  3. Conscious contributions to subliminal priming.

    PubMed

    Jaśkowski, Piotr

    2008-03-01

    Choice reaction times to visual stimuli (targets) may be influenced by preceding subliminal stimuli (primes). Some authors reported a straight priming effect i.e., responses were faster when primes and targets called for the same response than when they called for different responses. Others found the reversed pattern of results. Eimer and Schlaghecken [Eimer, M. & Schlaghecken, F. (2002). Links between conscious awareness and response inhibition: evidence from masked priming. Psychonomic Bulletin &Review, 9, 514-520.] showed recently that straight priming occurs whenever a prime is not efficiently masked thereby the information provided by the prime is accessible for consciousness. In the present study, a hypothesis is tested that straight priming is due to mediation of consciousness. To test this hypothesis, prime validity was manipulated. We showed that even when no mask was used so that participants could fully and consciously perceive the prime and participants were informed that primes were mostly invalid, for the short prime-target ISI interval (100 ms) straight priming occurred. The priming was inverse when the ISI was 800 ms. This indicates that participants were able to use the information provided by the prime to prepare the response opposite to that cued by the prime but only if the time between the prime and the target was long enough.

  4. Differential roles for snapin and synaptotagmin in the synaptic vesicle cycle.

    PubMed

    Yu, Szi-Chieh; Klosterman, Susan M; Martin, Ashley A; Gracheva, Elena O; Richmond, Janet E

    2013-01-01

    Evoked synaptic transmission is dependent on interactions between the calcium sensor Synaptotagmin I and the SNARE complex, comprised of Syntaxin, SNAP-25, and Synaptobrevin. Recent evidence suggests that Snapin may be an important intermediate in this process, through simultaneous interactions of Snapin dimers with SNAP-25 and Synaptotagmin. In support of this model, cultured neurons derived from embryonically lethal Snapin null mutant mice exhibit desynchronized release and a reduced readily releasable vesicle pool. Based on evidence that a dimerization-defective Snapin mutation specifically disrupts priming, Snapin is hypothesized to stabilize primed vesicles by structurally coupling Synaptotagmin and SNAP-25. To explore this model in vivo we examined synaptic transmission in viable, adult C. elegans Snapin (snpn-1) mutants. The kinetics of synaptic transmission were unaffected at snpn-1 mutant neuromuscular junctions (NMJs), but the number of docked, fusion competent vesicles was significantly reduced. However, analyses of snt-1 and snt-1;snpn-1 double mutants suggest that the docking role of SNPN-1 is independent of Synaptotagmin. Based on these results we propose that the primary role of Snapin in C. elegans is to promote vesicle priming, consistent with the stabilization of SNARE complex formation through established interactions with SNAP-25 upstream of the actions of Synaptotagmin in calcium-sensing and endocytosis.

  5. Masked priming effect reflects evidence accumulated by the prime.

    PubMed

    Kinoshita, Sachiko; Norris, Dennis

    2010-01-01

    In the same-different match task, masked priming is observed with the same responses but not different responses. Norris and Kinoshita's (2008) Bayesian reader account of masked priming explains this pattern based on the same principle as that explaining the absence of priming for nonwords in the lexical decision task. The pattern of priming follows from the way the model makes optimal decisions in the two tasks; priming does not depend on first activating the prime and then the target. An alternative explanation is in terms of a bias towards responding "same" that exactly counters the facilitatory effect of lexical access. The present study tested these two views by varying both the degree to which the prime predicts the response and the visibility of the prime. Unmasked primes produced effects expected from the view that priming is influenced by the degree to which the prime predicts the response. In contrast, with masked primes, the size of priming for the same response was completely unaffected by predictability. These results rule out response bias as an explanation of the absence of masked priming for different responses and, in turn, indicate that masked priming is not a consequence of automatic lexical access of the prime.

  6. Largest known twin primes and Sophie Germain primes

    NASA Astrophysics Data System (ADS)

    Indlekofer, Karl-Heinz; Járai, Antal

    The numbers 242206083* 2^38880+-1 are twin primes. The number p=2375063906985* 2^19380-1 is a Sophie Germain prime, i.e. p and 2p+1 are both primes. For p=4610194180515* 2^ 5056-1, the numbers p, p+2 and 2p+1 are all primes.

  7. Synaptic Vesicle Exocytosis

    PubMed Central

    Südhof, Thomas C.; Rizo, Josep

    2011-01-01

    Presynaptic nerve terminals release neurotransmitters by synaptic vesicle exocytosis. Membrane fusion mediating synaptic exocytosis and other intracellular membrane traffic is affected by a universal machinery that includes SNARE (for “soluble NSF-attachment protein receptor”) and SM (for “Sec1/Munc18-like”) proteins. During fusion, vesicular and target SNARE proteins assemble into an α-helical trans-SNARE complex that forces the two membranes tightly together, and SM proteins likely wrap around assembling trans-SNARE complexes to catalyze membrane fusion. After fusion, SNARE complexes are dissociated by the ATPase NSF (for “N-ethylmaleimide sensitive factor”). Fusion-competent conformations of SNARE proteins are maintained by chaperone complexes composed of CSPα, Hsc70, and SGT, and by nonenzymatically acting synuclein chaperones; dysfunction of these chaperones results in neurodegeneration. The synaptic membrane-fusion machinery is controlled by synaptotagmin, and additionally regulated by a presynaptic protein matrix (the “active zone”) that includes Munc13 and RIM proteins as central components. PMID:22026965

  8. Phosphorylation of synaptotagmin-1 controls a post-priming step in PKC-dependent presynaptic plasticity

    PubMed Central

    de Jong, Arthur P. H.; Meijer, Marieke; Saarloos, Ingrid; Cornelisse, Lennart Niels; Toonen, Ruud F. G.; Sørensen, Jakob B.; Verhage, Matthijs

    2016-01-01

    Presynaptic activation of the diacylglycerol (DAG)/protein kinase C (PKC) pathway is a central event in short-term synaptic plasticity. Two substrates, Munc13-1 and Munc18-1, are essential for DAG-induced potentiation of vesicle priming, but the role of most presynaptic PKC substrates is not understood. Here, we show that a mutation in synaptotagmin-1 (Syt1T112A), which prevents its PKC-dependent phosphorylation, abolishes DAG-induced potentiation of synaptic transmission in hippocampal neurons. This mutant also reduces potentiation of spontaneous release, but only if alternative Ca2+ sensors, Doc2A/B proteins, are absent. However, unlike mutations in Munc13-1 or Munc18-1 that prevent DAG-induced potentiation, the synaptotagmin-1 mutation does not affect paired-pulse facilitation. Furthermore, experiments to probe vesicle priming (recovery after train stimulation and dual application of hypertonic solutions) also reveal no abnormalities. Expression of synaptotagmin-2, which lacks a seven amino acid sequence that contains the phosphorylation site in synaptotagmin-1, or a synaptotagmin-1 variant with these seven residues removed (Syt1Δ109–116), supports normal DAG-induced potentiation. These data suggest that this seven residue sequence in synaptotagmin-1 situated in the linker between the transmembrane and C2A domains is inhibitory in the unphosphorylated state and becomes permissive of potentiation upon phosphorylation. We conclude that synaptotagmin-1 phosphorylation is an essential step in PKC-dependent potentiation of synaptic transmission, acting downstream of the two other essential DAG/PKC substrates, Munc13-1 and Munc18-1. PMID:27091977

  9. Phosphorylation of synaptotagmin-1 controls a post-priming step in PKC-dependent presynaptic plasticity.

    PubMed

    de Jong, Arthur P H; Meijer, Marieke; Saarloos, Ingrid; Cornelisse, Lennart Niels; Toonen, Ruud F G; Sørensen, Jakob B; Verhage, Matthijs

    2016-05-03

    Presynaptic activation of the diacylglycerol (DAG)/protein kinase C (PKC) pathway is a central event in short-term synaptic plasticity. Two substrates, Munc13-1 and Munc18-1, are essential for DAG-induced potentiation of vesicle priming, but the role of most presynaptic PKC substrates is not understood. Here, we show that a mutation in synaptotagmin-1 (Syt1(T112A)), which prevents its PKC-dependent phosphorylation, abolishes DAG-induced potentiation of synaptic transmission in hippocampal neurons. This mutant also reduces potentiation of spontaneous release, but only if alternative Ca(2+) sensors, Doc2A/B proteins, are absent. However, unlike mutations in Munc13-1 or Munc18-1 that prevent DAG-induced potentiation, the synaptotagmin-1 mutation does not affect paired-pulse facilitation. Furthermore, experiments to probe vesicle priming (recovery after train stimulation and dual application of hypertonic solutions) also reveal no abnormalities. Expression of synaptotagmin-2, which lacks a seven amino acid sequence that contains the phosphorylation site in synaptotagmin-1, or a synaptotagmin-1 variant with these seven residues removed (Syt1(Δ109-116)), supports normal DAG-induced potentiation. These data suggest that this seven residue sequence in synaptotagmin-1 situated in the linker between the transmembrane and C2A domains is inhibitory in the unphosphorylated state and becomes permissive of potentiation upon phosphorylation. We conclude that synaptotagmin-1 phosphorylation is an essential step in PKC-dependent potentiation of synaptic transmission, acting downstream of the two other essential DAG/PKC substrates, Munc13-1 and Munc18-1.

  10. How important is a prime's gestalt for subliminal priming?

    PubMed

    Jaśkowski, Piotr; Slósarek, Maciej

    2007-06-01

    Masked stimuli (primes) can affect the preparation of a motor response to subsequently presented target stimuli. Under some conditions, reactions to the main stimulus can be facilitated (straight priming) or inhibited (inverse priming) when preceded by a compatible prime (calling for the same response). In the majority of studies in which inverse priming was demonstrated arrows pointing left or right were used as prime and targets. There is, however, evidence that arrows are special overlearned stimuli which are processed in a favorable way. Here we report three experiments designated to test whether the "arrowness" of primes/targets is a sufficient condition for inverse priming. The results clearly show that although inverse priming appeared when non-arrow shapes were used, the magnitude of the priming effect was larger with arrows. The possible reasons for this effect are discussed.

  11. Benzaldehyde-functionalized Polymer Vesicles

    PubMed Central

    Sun, Guorong; Fang, Huafeng; Cheng, Chong; Lu, Peng; Zhang, Ke; Walker, Amy V.; Taylor, John-Stephen A.; Wooley, Karen L.

    2009-01-01

    Polymer vesicles with diameters of ca. 100-600 nm and bearing benzaldehyde functionalities within the vesicular walls were constructed through self assembly of an amphiphilic block copolymer PEO45-b-PVBA26 in water. The reactivity of the benzaldehyde functionalities was verified by crosslinking the polymersomes, and also by a one-pot crosslinking and functionalization approach to further render the vesicles fluorescent, each via reductive amination. In vitro studies found these labelled nanostructures to undergo cell association. PMID:19309173

  12. Neurotransmitter Release: The Last Millisecond in the Life of a Synaptic Vesicle

    PubMed Central

    Südhof, Thomas C.

    2013-01-01

    During an action potential, Ca2+ entering a presynaptic terminal triggers synaptic vesicle exocytosis and neurotransmitter release in less than a millisecond. How does Ca2+ stimulate release so rapidly and precisely? Work over the last decades revealed that Ca2+-binding to synaptotagmin triggers release by stimulating synaptotagmin-binding to a core machinery composed of SNARE and SM proteins that mediates membrane fusion during exocytosis. Complexin adaptor proteins assist synaptotagmin by activating and clamping this core fusion machinery. Synaptic vesicles containing synaptotagmin are positioned at the active zone, the site of vesicle fusion, by a protein complex containing RIM proteins. RIM proteins simultaneously activate docking and priming of synaptic vesicles and recruit Ca2+-channels to active zones, thereby connecting in a single complex primed synaptic vesicles to Ca2+-channels. This architecture allows direct flow of Ca2+-ions from Ca2+-channels to synaptotagmin, which then triggers fusion, thus mediating tight millisecond coupling of an action potential to neurotransmitter release. PMID:24183019

  13. Extracellular Vesicles in Renal Pathophysiology

    PubMed Central

    Pomatto, Margherita A. C.; Gai, Chiara; Bussolati, Benedetta; Camussi, Giovanni

    2017-01-01

    Extracellular vesicles are a heterogeneous population of microparticles released by virtually all living cells which have been recently widely investigated in different biological fields. They are typically composed of two primary types (exosomes and microvesicles) and are recently commanding increasing attention as mediators of cellular signaling. Indeed, these vesicles can affect recipient cells by carrying and delivering complex cargos of biomolecules (including proteins, lipids and nucleic acids), protected from enzymatic degradation in the environment. Their importance has been demonstrated in the pathophysiology of several organs, in particular in kidney, where different cell types secrete extracellular vesicles that mediate their communication with downstream urinary tract cells. Over the past few years, evidence has been shown that vesicles participate in kidney development and normal physiology. Moreover, EVs are widely demonstrated to be implicated in cellular signaling during renal regenerative and pathological processes. Although many EV mechanisms are still poorly understood, in particular in kidney, the discovery of their role could help to shed light on renal biological processes which are so far elusive. Lastly, extracellular vesicles secreted by renal cells gather in urine, thus becoming a great resource for disease or recovery markers and a promising non-invasive diagnostic instrument for renal disease. In the present review, we discuss the most recent findings on the role of extracellular vesicles in renal physiopathology and their potential implication in diagnosis and therapy. PMID:28638822

  14. Extracellular vesicles in renal disease.

    PubMed

    Karpman, Diana; Ståhl, Anne-Lie; Arvidsson, Ida

    2017-09-01

    Extracellular vesicles, such as exosomes and microvesicles, are host cell-derived packages of information that allow cell-cell communication and enable cells to rid themselves of unwanted substances. The release and uptake of extracellular vesicles has important physiological functions and may also contribute to the development and propagation of inflammatory, vascular, malignant, infectious and neurodegenerative diseases. This Review describes the different types of extracellular vesicles, how they are detected and the mechanisms by which they communicate with cells and transfer information. We also describe their physiological functions in cellular interactions, such as in thrombosis, immune modulation, cell proliferation, tissue regeneration and matrix modulation, with an emphasis on renal processes. We discuss how the detection of extracellular vesicles could be utilized as biomarkers of renal disease and how they might contribute to disease processes in the kidney, such as in acute kidney injury, chronic kidney disease, renal transplantation, thrombotic microangiopathies, vasculitides, IgA nephropathy, nephrotic syndrome, urinary tract infection, cystic kidney disease and tubulopathies. Finally, we consider how the release or uptake of extracellular vesicles can be blocked, as well as the associated benefits and risks, and how extracellular vesicles might be used to treat renal diseases by delivering therapeutics to specific cells.

  15. Extracellular Vesicles in Renal Pathophysiology.

    PubMed

    Pomatto, Margherita A C; Gai, Chiara; Bussolati, Benedetta; Camussi, Giovanni

    2017-01-01

    Extracellular vesicles are a heterogeneous population of microparticles released by virtually all living cells which have been recently widely investigated in different biological fields. They are typically composed of two primary types (exosomes and microvesicles) and are recently commanding increasing attention as mediators of cellular signaling. Indeed, these vesicles can affect recipient cells by carrying and delivering complex cargos of biomolecules (including proteins, lipids and nucleic acids), protected from enzymatic degradation in the environment. Their importance has been demonstrated in the pathophysiology of several organs, in particular in kidney, where different cell types secrete extracellular vesicles that mediate their communication with downstream urinary tract cells. Over the past few years, evidence has been shown that vesicles participate in kidney development and normal physiology. Moreover, EVs are widely demonstrated to be implicated in cellular signaling during renal regenerative and pathological processes. Although many EV mechanisms are still poorly understood, in particular in kidney, the discovery of their role could help to shed light on renal biological processes which are so far elusive. Lastly, extracellular vesicles secreted by renal cells gather in urine, thus becoming a great resource for disease or recovery markers and a promising non-invasive diagnostic instrument for renal disease. In the present review, we discuss the most recent findings on the role of extracellular vesicles in renal physiopathology and their potential implication in diagnosis and therapy.

  16. Synaptic Vesicle Pools: An Update

    PubMed Central

    Denker, Annette; Rizzoli, Silvio O.

    2010-01-01

    During the last few decades synaptic vesicles have been assigned to a variety of functional and morphological classes or “pools”. We have argued in the past (Rizzoli and Betz, 2005) that synaptic activity in several preparations is accounted for by the function of three vesicle pools: the readily releasable pool (docked at active zones and ready to go upon stimulation), the recycling pool (scattered throughout the nerve terminals and recycling upon moderate stimulation), and finally the reserve pool (occupying most of the vesicle clusters and only recycling upon strong stimulation). We discuss here the advancements in the vesicle pool field which took place in the ensuing years, focusing on the behavior of different pools under both strong stimulation and physiological activity. Several new findings have enhanced the three-pool model, with, for example, the disparity between recycling and reserve vesicles being underlined by the observation that the former are mobile, while the latter are “fixed”. Finally, a number of altogether new concepts have also evolved such as the current controversy on the identity of the spontaneously recycling vesicle pool. PMID:21423521

  17. Asymmetric Vesicle Instability in Extensional Flow

    NASA Astrophysics Data System (ADS)

    Spann, Andrew; Zhao, Hong; Shaqfeh, Eric

    2012-11-01

    Previous researchers have chronicled the breakup of drops in an extensional flow as they stretch into a dumbbell shape with a long thin neck. Motivated by recent experimental observations, we study an apparently similar problem with vesicles, which are deformable but incompressible membranes that conserve area and volume. First, we simulate vesicles in an unbounded uniaxial extensional flow which are given general radial perturbations from an initially stable symmetric equilibrium state. For sufficiently low reduced volume (< 0.74 at matched inner/outer viscosity) there exists a capillary number at which an asymmetric perturbation mode will grow, resulting in the formation of an asymmetric dumbbell shape with a thin connecting cylindrical bridge analogous to the shapes associated with drop breakup. Our simulations help elucidate a mechanism for this instability based on a competition between internal pressure differentials in the vesicle resulting from the membrane bending force and ambient flow. We compare and contrast this transition to the ``standard'' drop breakup transition. Funded by NSF GRFP and Stanford Graduate Fellowship.

  18. Unbinding of adhesive vesicles

    NASA Astrophysics Data System (ADS)

    Brochard-Wyart, FrançOise de Gennes, Pierre-Gilles

    We consider a vesicle, bound on one side to a pipette and sticking on the other side to a flat plate. When a pulling force f is applied to the pipette, the radius Rc of the contact patch decreases, and jumps to zero at a critical value of the force. We present here an extension of the Evans theory for these processes. Then we discuss the dynamics of separation for two distinct cases: (a) nonspecific adhesion; and (b) specific adhesion induced by mobile proteins. To cite this article: F. Brochard-Wyart, P.-G. de Gennes, C. R. Physique 4 (2003). On considère une vésicule qui, aspirée par une pipette d'un coteé adhèe de l'autre sur une surface plane. Lorsqu'on tire sur la pipette avec une force f le rayon du contact adhesif decroit, et s'annule brusquement a une valeur critique de la force. On présente ici une extension de la théorie d'Evans pour interpréter ces processus de détachement. Puis l'on discute la dynamique de la séparation pour deux cas distincts : (a) adhésion non spécifique ; et (b) adhésion spécifique par des protéines mobiles. Pour citer cet article : F. Brochard-Wyart, P.-G. de Gennes, C. R. Physique 4 (2003).

  19. Mutations in the major gas vesicle protein GvpA and impacts on gas vesicle formation in Haloferax volcanii.

    PubMed

    Knitsch, Regine; Schneefeld, Marie; Weitzel, Kerstin; Pfeifer, Felicitas

    2017-09-12

    Gas vesicles are proteinaceous, gas-filled nanostructures produced by some bacteria and archaea. The hydrophobic major structural protein GvpA forms the ribbed gas vesicle wall. An in-silico 3D-model of GvpA of the predicted coil-α1-β1-β2-α2-coil structure is available and implies that the two β-chains constitute the hydrophobic interior surface of the gas vesicle wall. To test the importance of individual amino acids in GvpA we performed 85 single substitutions and analyzed these variants in Haloferax volcanii ΔA + Amut transformants for their ability to form gas vesicles (Vac(+) phenotype). In most cases, an alanine substitution of a non-polar residue did not abolish gas vesicle formation, but the replacement of single non-polar by charged residues in β1 or β2 resulted in Vac(-) transformants. A replacement of residues near the β-turn altered the spindle-shape to a cylindrical morphology of the gas vesicles. Vac(-) transformants were also obtained with alanine substitutions of charged residues of helix α1 suggesting that these amino acids form salt-bridges with another GvpA monomer. In helix α2, only the alanine substitution of His53 or Tyr54, led to Vac(-) transformants, whereas most other substitutions had no effect. We discuss our results in respect to the GvpA structure and data available from solid-state NMR. © 2017 John Wiley & Sons Ltd.

  20. Overall energy conversion efficiency of a photosynthetic vesicle

    DOE PAGES

    Sener, Melih; Strumpfer, Johan; Singharoy, Abhishek; ...

    2016-08-26

    The chromatophore of purple bacteria is an intracellular spherical vesicle that exists in numerous copies in the cell and that efficiently converts sunlight into ATP synthesis, operating typically under low light conditions. Building on an atomic-level structural model of a low-light-adapted chromatophore vesicle from Rhodobacter sphaeroides , we investigate the cooperation between more than a hundred protein complexes in the vesicle. The steady-state ATP production rate as a function of incident light intensity is determined after identifying quinol turnover at the cytochrome bc1 complex (cytb⁢c1) as rate limiting and assuming that the quinone/quinol pool of about 900 molecules actsmore » in a quasi-stationary state. For an illumination condition equivalent to 1% of full sunlight, the vesicle exhibits an ATP production rate of 82 ATP molecules/s. The energy conversion efficiency of ATP synthesis at illuminations corresponding to 1%–5% of full sunlight is calculated to be 0.12–0.04, respectively. The vesicle stoichiometry, evolutionarily adapted to the low light intensities in the habitat of purple bacteria, is suboptimal for steady-state ATP turnover for the benefit of protection against over-illumination.« less

  1. Overall energy conversion efficiency of a photosynthetic vesicle.

    PubMed

    Sener, Melih; Strumpfer, Johan; Singharoy, Abhishek; Hunter, C Neil; Schulten, Klaus

    2016-08-26

    The chromatophore of purple bacteria is an intracellular spherical vesicle that exists in numerous copies in the cell and that efficiently converts sunlight into ATP synthesis, operating typically under low light conditions. Building on an atomic-level structural model of a low-light-adapted chromatophore vesicle from Rhodobacter sphaeroides, we investigate the cooperation between more than a hundred protein complexes in the vesicle. The steady-state ATP production rate as a function of incident light intensity is determined after identifying quinol turnover at the cytochrome bc1 complex (cytb⁢c1) as rate limiting and assuming that the quinone/quinol pool of about 900 molecules acts in a quasi-stationary state. For an illumination condition equivalent to 1% of full sunlight, the vesicle exhibits an ATP production rate of 82 ATP molecules/s. The energy conversion efficiency of ATP synthesis at illuminations corresponding to 1%-5% of full sunlight is calculated to be 0.12-0.04, respectively. The vesicle stoichiometry, evolutionarily adapted to the low light intensities in the habitat of purple bacteria, is suboptimal for steady-state ATP turnover for the benefit of protection against over-illumination.

  2. Overall energy conversion efficiency of a photosynthetic vesicle

    PubMed Central

    Sener, Melih; Strumpfer, Johan; Singharoy, Abhishek; Hunter, C Neil; Schulten, Klaus

    2016-01-01

    The chromatophore of purple bacteria is an intracellular spherical vesicle that exists in numerous copies in the cell and that efficiently converts sunlight into ATP synthesis, operating typically under low light conditions. Building on an atomic-level structural model of a low-light-adapted chromatophore vesicle from Rhodobacter sphaeroides, we investigate the cooperation between more than a hundred protein complexes in the vesicle. The steady-state ATP production rate as a function of incident light intensity is determined after identifying quinol turnover at the cytochrome bc1 complex (cytb⁢c1) as rate limiting and assuming that the quinone/quinol pool of about 900 molecules acts in a quasi-stationary state. For an illumination condition equivalent to 1% of full sunlight, the vesicle exhibits an ATP production rate of 82 ATP molecules/s. The energy conversion efficiency of ATP synthesis at illuminations corresponding to 1%–5% of full sunlight is calculated to be 0.12–0.04, respectively. The vesicle stoichiometry, evolutionarily adapted to the low light intensities in the habitat of purple bacteria, is suboptimal for steady-state ATP turnover for the benefit of protection against over-illumination. DOI: http://dx.doi.org/10.7554/eLife.09541.001 PMID:27564854

  3. Extracellular vesicles during Herpes Simplex Virus type 1 infection: an inquire.

    PubMed

    Kalamvoki, Maria; Deschamps, Thibaut

    2016-04-05

    Extracellular vesicles are defined as a heterogeneous group of vesicles that are released by prokaryotic to higher eukaryotic cells and by plant cells in an evolutionary conserved manner. The significance of these vesicles lies in their capacity to transfer selected cargo composed of proteins, lipids and nucleic acids to both recipient and parent cells and to influence various physiological and pathological functions. Microorganisms such as parasites, fungi and protozoa and even single cell organisms such as bacteria generate extracellular vesicles. In addition, several viruses have evolved strategies to hijack the extracellular vesicles for egress or to alter the surrounding environment. The thesis of this article is that: a) during HSV-1 infection vesicles are delivered from infected to uninfected cells that influence the infection; b) the cargo of these vesicles consists of viral and host transcripts (mRNAs, miRNAs and non-coding RNAs) and proteins including innate immune components, such as STING; and c) the viral vesicles carry the tetraspanins CD9, CD63 and CD81, which are considered as markers of exosomes. Therefore, we assume that the STING-carrying vesicles, produced during HSV-1 infection, are reminiscent to exosomes. The presumed functions of the exosomes released from HSV-1 infected cells include priming the recipient cells and accelerating antiviral responses to control the dissemination of the virus. This may be one strategy used by the virus to prevent the elimination by the host and establish persistent infection. In conclusion, the modification of the cargo of exosomes appears to be part of the strategy that HSV-1 has evolved to establish lifelong persistent infections into the human body to ensure successful dissemination between individuals.

  4. Clathrin regenerates synaptic vesicles from endosomes

    PubMed Central

    Watanabe, Shigeki; Trimbuch, Thorsten; Camacho-Pérez, Marcial; Rost, Benjamin R.; Brokowski, Bettina; Söhl-Kielczynski, Berit; Felies, Annegret; Davis, M. Wayne; Rosenmund, Christian; Jorgensen, Erik M.

    2014-01-01

    Summary Ultrafast endocytosis can retrieve a single large endocytic vesicle as fast as 50-100 ms after synaptic vesicle fusion. However, the fate of the large endocytic vesicles is not known. Here we demonstrate that these vesicles transition to a synaptic endosome about one second after stimulation. The endosome is resolved into coated vesicles after 3 seconds, which in turn become small-diameter synaptic vesicles 5-6 seconds after stimulation. We disrupted clathrin function using RNAi and found that clathrin is not required for ultrafast endocytosis but is required to generate synaptic vesicles from the endosome. Ultrafast endocytosis fails when actin polymerization is disrupted, or when neurons are stimulated at room temperature instead of physiological temperature. In the absence of ultrafast endocytosis, synaptic vesicles are retrieved directly from the plasma membrane by clathrin-mediated endocytosis. These results explain in large part discrepancies among published experiments concerning the role of clathrin in synaptic vesicle endocytosis. PMID:25296249

  5. When to biopsy seminal vesicles.

    PubMed

    Panach-Navarrete, J; García-Morata, F; Hernández-Medina, J A; Martínez-Jabaloyas, J M

    2015-05-01

    The involvement of seminal vesicles in prostate cancer can affect the prognosis and determine the treatment. The objective of this study was to determine whether we could predict its infiltration at the time of the prostate biopsy to know when to indicate the biopsy of the seminal vesicles. observational retrospective study of 466 patients who underwent seminal vesicle biopsy. The indication for this biopsy was a prostate-specific antigen (PSA) level greater than 10 ng/ml or an asymmetric or obliterated prostatoseminal angle. The following variables were included in the analysis: PSA level, PSA density, prostate volume, number of cores biopsied, suspicious rectal examination, and preservation of the prostatoseminal angle, studying its relationship with the involvement of the seminal vesicles. Forty-one patients (8.8%) had infiltrated seminal vesicles and 425 (91.2%) had no involvement. In the univariate analysis, the cases with infiltration had a higher mean PSA level (P < .01) and PSA density (P < .01), as well as a lower mean prostate volume (P < .01). A suspicious rectal examination (20.7% of the infiltrated vesicles) and the obliteration or asymmetry of the prostatoseminal angle (33.3% of the infiltrated vesicles) were significantly related to the involvement (P < .01). In the multivariate analysis, we concluded that the probability of having infiltrated seminal vesicles is 5.19 times higher if the prostatoseminal angle is not preserved (P < .01), 4.65 times higher for PSA levels >19.60 ng/dL (P < .01) and 2.95 times higher if there is a suspicious rectal examination (P = .014). Furthermore, this probability increases by 1.04 times for each unit of prostate volume lower (P < .01). The ROC curves showed maximum sensitivity and specificity at 19.6 ng/mL for PSA and 0.39 for PSA density. In this series, greater involvement of seminal vesicles was associated with a PSA level ≥20 ng/ml, a suspicious rectal examination and a lack of prostatoseminal angle

  6. Extracellular Vesicles in Lung Disease.

    PubMed

    Kubo, Hiroshi

    2017-07-03

    Accumulating evidence suggests that extracellular vesicles (EVs) play a role in the pathogenesis of lung diseases. These vesicles include exosomes, ectosomes (ie, microparticles, extracellular vesicles, microvesicles, and shedding vesicles), and apoptotic bodies. Exosomes are generated by inward budding of the membrane (endocytosis), subsequent forming of multivesicular bodies, and release by exocytosis. Ectosomes are formed by outward blebbing from the plasma membrane and are then released by proteolytic cleavage from the cell surface. Apoptotic bodies are generated on apoptotic cell shrinkage and death. Extracellular vesicles are released when the cells are activated or undergo apoptosis under inflammatory conditions. The number and types of released EVs are different according to the pathophysiological status of the disease. Therefore, EVs can be novel biomarkers for various lung diseases. EVs contain several molecules, including proteins, mRNA, microRNA, and DNA; they transfer these molecules to distant recipient cells. Circulating EVs modify the targeted cells and influence the microenvironment of the lungs. For this unique capability, EVs are expected to be a new drug delivery system and a novel therapeutic target. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  7. Ellipsoidal Relaxation of Deformed Vesicles

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Lira, Rafael B.; Riske, Karin A.; Dimova, Rumiana; Lin, Hao

    2015-09-01

    Theoretical analysis and experimental quantification on the ellipsoidal relaxation of vesicles are presented. The current work reveals the simplicity and universal aspects of this process. The Helfrich formula is shown to apply to the dynamic relaxation of moderate-to-high tension membranes, and a closed-form solution is derived which predicts the vesicle aspect ratio as a function of time. Scattered data are unified by a time scale, which leads to a similarity behavior, governed by a distinctive solution for each vesicle type. Two separate regimes in the relaxation are identified, namely, the "entropic" and the "constant-tension" regimes. The bending rigidity and the initial membrane tension can be simultaneously extracted from the data analysis, posing the current approach as an effective means for the mechanical analysis of biomembranes.

  8. Temperature-Dependent Differences between Readily Releasable and Reserve Pool Vesicles in Chromaffin Cells

    PubMed Central

    Haynes, Christy L.; Siff, Lauren N.; Wightman, R. Mark

    2007-01-01

    Summary Statistical differences between amperometric traces recorded from chromaffin cells using K+ and Ba2+ secretagogues support the assertion that readily releasable pool (RRP) and reserve pool (RP) vesicles can be probed with pool-specific secretagogues. Release from the RRP was evoked by K+ while release from the RP was evoked by Ba2+. Similar temperature-dependent changes in spike area and half-width for both pools suggest that the content of RRP and RP vesicles is similar and packaged in the same way. Differences between the vesicle pools were revealed in the temperature dependence of spike frequency. While the burst spike frequency of the RRP, which is comprised of pre-docked and primed vesicles, increased 2.8% per °C, the RP spike frequency increased 12% per °C. This difference is attributed to a temperature dependent mobilization of the RP. Furthermore, the RP exhibited more foot events at room temperature than the RRP but this difference was not apparent at 37°C. This trend suggests that RP vesicle membranes have a compromised surface tension compared to RRP vesicles. Collectively, the changes of release characteristics with temperature reveal distinctions between the RRP and the RP. PMID:17467077

  9. Lipid transfer between vesicles: effect of high vesicle concentration.

    PubMed Central

    Almeida, P F

    1999-01-01

    The problem of the desorption of a lipid molecule from a lipid vesicle (donor) and its incorporation into another vesicle (acceptor) at high acceptor concentrations, which has been investigated experimentally (Jones, J. D. and Thompson, T. E., 1990. Biochemistry, 29:1593-1600), is analyzed here from a theoretical point of view, formulated in terms of the diffusion equation with appropriate boundary conditions. The goal is to determine whether or not the observed acceleration of the off-rate from a donor is caused by interaction with an acceptor vesicle at short range, or is simply the result of statistical effects due the proximity of the acceptor and its influence on the probability of the test lipid returning to the donor. We establish a correspondence between the theoretical parameters and the experimental, thermodynamic and dynamic variables entering the problem. The solution shows that, because of the extremely high Gibbs activation energy for desorption of a phospholipid, the process would always be first-order, even at very high vesicle concentrations. This means that acceleration of the off-rate must be due to donor-acceptor interactions at short distances, as proposed in the experimental work. PMID:10096890

  10. Transfer of Oleic Acid between Albumin and Phospholipid Vesicles

    NASA Astrophysics Data System (ADS)

    Hamilton, James A.; Cistola, David P.

    1986-01-01

    The net transfer of oleic acid between egg phosphatidylcholine unilamellar vesicles and bovine serum albumin has been monitored by 13C NMR spectroscopy and 90% isotopically substituted [1-13C]oleic acid. The carboxyl chemical shifts of oleic acid bound to albumin were different from those for oleic acid in phospholipid vesicles. Therefore, in mixtures of donor particles (vesicles or albumin with oleic acid) and acceptor particles (fatty acid-free albumin or vesicles), the equilibrium distribution of oleic acid was determined from chemical shift and peak intensity data without separation of donor and acceptor particles. In a system containing equal masses of albumin and phospholipid and a stoichiometry of 4-5 mol of oleic acid per mol of albumin, the oleic acid distribution was pH dependent, with >= 80% of the oleic acid associated with albumin at pH 7.4; association was >= 90% at pH 8.0. Decreasing the pH below 7.4 markedly decreased the proportion of fatty acid bound to albumin; at pH 5.4, <= 10% of the oleic acid was bound to albumin and >90% was associated with vesicles. The distribution was reversible with pH and was independent of whether vesicles or albumin acted as a donor. These data suggest that pH may strongly influence the partitioning of fatty acid between cellular membranes and albumin. The 13C NMR method is also advantageous because it provides information about the structural environments of oleic acid bound to albumin or phospholipid, the ionization state of oleic acid in each environment, and the structural integrity of the vesicles. In addition, minimum and maximum limits for the exchange rates of oleic acid among different environments were obtained from the NMR data.

  11. Prime Retrieval of Motor Responses in Negative Priming

    ERIC Educational Resources Information Center

    Mayr, Susanne; Buchner, Axel; Dentale, Sandra

    2009-01-01

    Three auditory identification experiments were designed to specify the prime-response retrieval model of negative priming (S. Mayr & A. Buchner, 2006), which assumes that the prime response is retrieved in ignored repetition trials and interferes with probe responding. In Experiment 1, shortly before (in Experiment 1A) or after (in Experiment 1B)…

  12. Prime Retrieval of Motor Responses in Negative Priming

    ERIC Educational Resources Information Center

    Mayr, Susanne; Buchner, Axel; Dentale, Sandra

    2009-01-01

    Three auditory identification experiments were designed to specify the prime-response retrieval model of negative priming (S. Mayr & A. Buchner, 2006), which assumes that the prime response is retrieved in ignored repetition trials and interferes with probe responding. In Experiment 1, shortly before (in Experiment 1A) or after (in Experiment 1B)…

  13. Spontaneous charged lipid transfer between lipid vesicles.

    PubMed

    Richens, Joanna L; Tyler, Arwen I I; Barriga, Hanna M G; Bramble, Jonathan P; Law, Robert V; Brooks, Nicholas J; Seddon, John M; Ces, Oscar; O'Shea, Paul

    2017-10-03

    An assay to study the spontaneous charged lipid transfer between lipid vesicles is described. A donor/acceptor vesicle system is employed, where neutrally charged acceptor vesicles are fluorescently labelled with the electrostatic membrane probe Fluoresceinphosphatidylethanolamine (FPE). Upon addition of charged donor vesicles, transfer of negatively charged lipid occurs, resulting in a fluorescently detectable change in the membrane potential of the acceptor vesicles. Using this approach we have studied the transfer properties of a range of lipids, varying both the headgroup and the chain length. At the low vesicle concentrations chosen, the transfer follows a first-order process where lipid monomers are transferred presumably through the aqueous solution phase from donor to acceptor vesicle. The rate of transfer decreases with increasing chain length which is consistent with energy models previously reported for lipid monomer vesicle interactions. Our assay improves on existing methods allowing the study of a range of unmodified lipids, continuous monitoring of transfer and simplified experimental procedures.

  14. Synaptic vesicle distribution by conveyor belt.

    PubMed

    Moughamian, Armen J; Holzbaur, Erika L F

    2012-03-02

    The equal distribution of synaptic vesicles among synapses along the axon is critical for robust neurotransmission. Wong et al. show that the continuous circulation of synaptic vesicles throughout the axon driven by molecular motors ultimately yields this even distribution.

  15. Primed for pluripotency.

    PubMed

    Kunath, Tilo

    2011-03-04

    To date, pluripotent epiblast stem cells (EpiSCs) had only been derived from postimplantation mouse embryos. In this issue of Cell Stem Cell, Najm et al. (2011) demonstrate that EpiSCs can be routinely derived from preimplantation embryos, showing that both human and mouse blastocysts can produce the same class of primed pluripotent cells.

  16. "Fell" Primes "Fall", but Does "Bell" Prime "Ball"? Masked Priming with Irregularly-Inflected Primes

    ERIC Educational Resources Information Center

    Crepaldi, Davide; Rastle, Kathleen; Coltheart, Max; Nickels, Lyndsey

    2010-01-01

    Recent masked priming experiments have brought to light a morphological level of analysis that is exclusively based on the orthographic appearance of words, so that it breaks down corner into corn- and -er, as well as dealer into deal- and -er (Rastle, Davis, & New, 2004). Being insensitive to semantic factors, this morpho-orthographic…

  17. Prime-Time Nutrition.

    ERIC Educational Resources Information Center

    Kaufman, Lois

    1980-01-01

    Presents a study identifying, analyzing, and describing messages on prime-time network television related to food, eating behavior, and ideal body image. Program content and commercials studied present conflicting messages: (1) that we eat in ways almost guaranteed to make us fat, and (2) that we strive to remain too slim. (JMF)

  18. "Fell" Primes "Fall", but Does "Bell" Prime "Ball"? Masked Priming with Irregularly-Inflected Primes

    ERIC Educational Resources Information Center

    Crepaldi, Davide; Rastle, Kathleen; Coltheart, Max; Nickels, Lyndsey

    2010-01-01

    Recent masked priming experiments have brought to light a morphological level of analysis that is exclusively based on the orthographic appearance of words, so that it breaks down corner into corn- and -er, as well as dealer into deal- and -er (Rastle, Davis, & New, 2004). Being insensitive to semantic factors, this morpho-orthographic…

  19. From primed construct to motivated behavior: validation processes in goal pursuit.

    PubMed

    Demarree, Kenneth G; Loersch, Chris; Briñol, Pablo; Petty, Richard E; Payne, B Keith; Rucker, Derek D

    2012-12-01

    Past research has found that primes can automatically initiate unconscious goal striving. Recent models of priming have suggested that this effect can be moderated by validation processes. According to a goal-validation perspective, primes should cause changes in one's motivational state to the extent people have confidence in the prime-related mental content. Across three experiments, we provided the first direct empirical evidence for this goal-validation account. Using a variety of goal priming manipulations (cooperation vs. competition, achievement, and self-improvement vs. saving money) and validity inductions (power, ease, and writing about confidence), we demonstrated that the impact of goal primes on behavior occurs to a greater extent when conditions foster confidence (vs. doubt) in mental contents. Indeed, when conditions foster doubt, goal priming effects are eliminated or counter to the implications of the prime. The implications of these findings for research on goal priming and validation processes are discussed.

  20. Portrait - Gemini 11 - Prime Crew

    NASA Image and Video Library

    1965-01-01

    S65-58504 (4 Nov. 1965) --- Astronauts Charles Conrad Jr., (right) prime crew command pilot, and Richard F. Gordon Jr., prime crew pilot, for the Gemini-Titan XI (GT-11) Earth-orbital mission. Photo credit: NASA

  1. FUSION-COMPETENT STATE INDUCED BY A C-TERMINAL HIV-1 FUSION PEPTIDE IN CHOLESTEROL-RICH MEMBRANES

    PubMed Central

    Apellániz, Beatriz; Nieva, José L.

    2015-01-01

    The replicative cycle of the Human Immunodeficiency Virus type-1 begins after fusion of the viral and target-cell membranes. The envelope glycoprotein gp41 transmembrane subunit contains conserved hydrophobic domains that engage and perturb the merging lipid bilayers. In this work, we have characterized the fusion-committed state generated in vesicles by CpreTM, a synthetic peptide derived from the sequence connecting the membrane-proximal external region (MPER) and the transmembrane domain (TMD) of gp41. Pre-loading cholesterol-rich vesicles with CpreTM rendered them competent for subsequent lipid-mixing with fluorescently-labeled target vesicles. Highlighting the physiological relevance of the lasting fusion-competent state, the broadly neutralizing antibody 4E10 bound to the CpreTM-primed vesicles and inhibited lipid-mixing. Heterotypic fusion assays disclosed dependence on the lipid composition of the vesicles that acted either as virus or cell membrane surrogates. Lipid-mixing exhibited above all a critical dependence on the cholesterol content in those experiments. We infer that the fusion-competent state described herein resembles bona-fide perturbations generated by the pre-hairpin MPER-TMD connection within the viral membrane. PMID:25617671

  2. Roles of BLOC-1 and Adaptor Protein-3 Complexes in Cargo Sorting to Synaptic Vesicles

    PubMed Central

    Newell-Litwa, Karen; Salazar, Gloria; Smith, Yoland

    2009-01-01

    Neuronal lysosomes and their biogenesis mechanisms are primarily thought to clear metabolites and proteins whose abnormal accumulation leads to neurodegenerative disease pathology. However, it remains unknown whether lysosomal sorting mechanisms regulate the levels of membrane proteins within synaptic vesicles. Using high-resolution deconvolution microscopy, we identified early endosomal compartments where both selected synaptic vesicle and lysosomal membrane proteins coexist with the adaptor protein complex 3 (AP-3) in neuronal cells. From these early endosomes, both synaptic vesicle membrane proteins and characteristic AP-3 lysosomal cargoes can be similarly sorted to brain synaptic vesicles and PC12 synaptic-like microvesicles. Mouse knockouts for two Hermansky–Pudlak complexes involved in lysosomal biogenesis from early endosomes, the ubiquitous isoform of AP-3 (Ap3b1−/−) and muted, defective in the biogenesis of lysosome-related organelles complex 1 (BLOC-1), increased the content of characteristic synaptic vesicle proteins and known AP-3 lysosomal proteins in isolated synaptic vesicle fractions. These phenotypes contrast with those of the mouse knockout for the neuronal AP-3 isoform involved in synaptic vesicle biogenesis (Ap3b2−/−), in which the content of select proteins was reduced in synaptic vesicles. Our results demonstrate that lysosomal and lysosome-related organelle biogenesis mechanisms regulate steady-state synaptic vesicle protein composition from shared early endosomes. PMID:19144828

  3. Penetration enhancer-containing vesicles: composition dependence of structural features and skin penetration ability.

    PubMed

    Manconi, M; Caddeo, C; Sinico, C; Valenti, D; Mostallino, M C; Lampis, S; Monduzzi, M; Fadda, A M

    2012-10-01

    In this work, we focused on how composition and preparation method of vesicles might affect their morphological features and delivery performances. Penetration Enhancer-containing Vesicles, PEVs, vesicles containing a water miscible penetration enhancer (Transcutol® P; 10%, 20%, 30% v/v) and encapsulating diclofenac sodium, were formulated and compared with conventional liposomes. A cheap and unpurified commercial mixture of phospholipids, fatty acids, and triglycerides (Phospholipon® 50) was used, and the effects of this heterogeneous composition (along with the presence or absence of transcutol and the production method) on vesicle morphology, size, surface charge, drug loading, and stability were investigated. The variations in vesicle structure, bilayer thickness, and number of lamellae were assessed by TEM and Small and Wide Angle X-ray Scattering, which also proved the liquid state of the vesicular bilayer. Further, vesicles were evaluated for ex vivo (trans)dermal delivery, and their mode of action was studied performing a pre-treatment test and confocal laser scanning microscopy analyses. Results showed the formation of multi- and unilamellar vesicles that provided improved diclofenac delivery to pig skin, influenced by vesicle lipid composition and structure. Images of the qualitative CLSM analyses support the conclusion that PEVs enhance drug transport by penetrating intact the stratum corneum, thanks to a synergic effect of vesicles and penetration enhancer. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Mechanisms of COPI vesicle formation

    PubMed Central

    Hsu, Victor W.; Yang, Jia-Shu

    2009-01-01

    Coat Protein I (COPI) is one of the most intensely investigated coat complexes. Numerous studies have contributed to a general understanding of how coat proteins act to initiate intracellular vesicular transport. This review highlights key recent findings that have shaped our current understanding of how COPI vesicles are formed. PMID:19854177

  5. Morphology of nematic and smectic vesicles

    PubMed Central

    Xing, Xiangjun; Shin, Homin; Bowick, Mark J.; Yao, Zhenwei; Jia, Lin; Li, Min-Hui

    2012-01-01

    Recent experiments on vesicles formed from block copolymers with liquid-crystalline side chains reveal a rich variety of vesicle morphologies. The additional internal order (“structure”) developed by these self-assembled block copolymer vesicles can lead to significantly deformed vesicles as a result of the delicate interplay between two-dimensional ordering and vesicle shape. The inevitable topological defects in structured vesicles of spherical topology also play an essential role in controlling the final vesicle morphology. Here we develop a minimal theoretical model for the morphology of the membrane structure with internal nematic/smectic order. Using both analytic and numerical approaches, we show that the possible low free energy morphologies include nano-size cylindrical micelles (nano-fibers), faceted tetrahedral vesicles, and ellipsoidal vesicles, as well as cylindrical vesicles. The tetrahedral vesicle is a particularly fascinating example of a faceted liquid-crystalline membrane. Faceted liquid vesicles may lead to the design of supramolecular structures with tetrahedral symmetry and new classes of nano-carriers. PMID:22431595

  6. Rab13 Traffics on Vesicles Independent of Prenylation*

    PubMed Central

    Ioannou, Maria S.; Girard, Martine; McPherson, Peter S.

    2016-01-01

    Rab GTPases are critical regulators of membrane trafficking. The canonical view is that Rabs are soluble in their inactive GDP-bound form, and only upon activation and conversion to their GTP-bound state are they anchored to membranes through membrane insertion of a C-terminal prenyl group. Here we demonstrate that C-terminal prenylation is not required for Rab13 to associate with and traffic on vesicles. Instead, inactive Rab13 appears to associate with vesicles via protein-protein interactions. Only following activation does Rab13 associate with the plasma membrane, presumably with insertion of the C-terminal prenyl group into the membrane. PMID:26969162

  7. Priming with NO controls redox state and prevents cadmium-induced general up-regulation of methionine sulfoxide reductase gene family in Arabidopsis.

    PubMed

    Méndez, Andrea A E; Pena, Liliana B; Benavides, María P; Gallego, Susana M

    2016-12-01

    In the present study we evaluated the pre-treatment (priming) of Arabidopsis thaliana plants with sodium nitroprusside (SNP), a NO-donor, as an interesting approach for improving plant tolerance to cadmium stress. We focused on the cell redox balance and on the methionine sulfoxide reductases (MSR) family as a key component of such response. MSR catalyse the reversible oxidation of MetSO residues back to Met. Five MSRA genes and nine MSRB genes have been identified in A. thaliana, coding for proteins with different subcellular locations. After treating 20 days-old A. thaliana (Col 0) plants with 100 μM CdCl2, increased protein carbonylation in leaf tissue, lower chlorophyll content and higher levels of reactive oxygen species (ROS) in chloroplasts were detected, together with increased accumulation of all MSR transcripts evaluated. Further analysis showed reduction in guaiacol peroxidase activity (GPX) and increased catalase (CAT) activity, with no effect on ascorbate peroxidase (APX) activity. Pre-exposition of plants to 100 μM SNP before cadmium treatment restored redox balance; this seems to be linked to a better performance of antioxidant defenses. Our results indicate that NO priming may be acting as a modulator of plant antioxidant system by interfering in oxidative responses and by preventing up-regulation of MSR genes caused by metal exposure. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  8. Masked Repetition Priming Using Magnetoencephalography

    ERIC Educational Resources Information Center

    Monahan, Philip J.; Fiorentino, Robert; Poeppel, David

    2008-01-01

    Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming.…

  9. Masked Repetition Priming Using Magnetoencephalography

    ERIC Educational Resources Information Center

    Monahan, Philip J.; Fiorentino, Robert; Poeppel, David

    2008-01-01

    Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming.…

  10. Superficial Priming in Episodic Recognition

    ERIC Educational Resources Information Center

    Dopkins, Stephen; Sargent, Jesse; Ngo, Catherine T.

    2010-01-01

    We explored the effect of superficial priming in episodic recognition and found it to be different from the effect of semantic priming in episodic recognition. Participants made recognition judgments to pairs of items, with each pair consisting of a prime item and a test item. Correct positive responses to the test item were impeded if the prime…

  11. Rhizosphere priming: a nutrient perspective

    USDA-ARS?s Scientific Manuscript database

    Rhizosphere priming is the change in decomposition of soil organic matter (SOM) caused by root activity. Rhizosphere priming plays a crucial role in soil carbon (C) dynamics and their response to global climate change. Rhizosphere priming may be affected by soil nutrient availability, but rhizospher...

  12. Priming Ditransitive Structures in Comprehension

    ERIC Educational Resources Information Center

    Arai, Manabu; van Gompel, Roger P. G.; Scheepers, Cristoph

    2007-01-01

    Many studies have shown evidence for syntactic priming during language production (e.g., Bock, 1986). It is often assumed that comprehension and production share similar mechanisms and that priming also occurs during comprehension (e.g., Pickering & Garrod, 2004). Research investigating priming during comprehension (e.g., Branigan et al., 2005 and…

  13. Rotavirus interaction with isolated membrane vesicles.

    PubMed

    Ruiz, M C; Alonso-Torre, S R; Charpilienne, A; Vasseur, M; Michelangeli, F; Cohen, J; Alvarado, F

    1994-06-01

    To gain information about the mechanism of epithelial cell infection by rotavirus, we studied the interaction of bovine rotavirus, RF strain, with isolated membrane vesicles from apical membrane of pig enterocytes. Vesicles were charged with high (quenching) concentrations of either carboxyfluorescein or calcein, and the rate of fluorophore release (dequenching) was monitored as a function of time after mixing with purified virus particles. Purified single-shelled particles and untrypsinized double-shelled ones had no effect. Trypsinized double-shelled virions induced carboxyfluorescein release according to sigmoid curves whose lag period and amplitude were a function of virus concentration and depended on both temperature and pH. The presence of 100 mM salts (Tris Cl, NaCl, or KCl) was required, since there was no reaction in isoosmotic salt-free sorbitol media. Other membrane vesicle preparations such as apical membranes of piglet enterocyte and rat placenta syncytiotrophoblasts, basolateral membranes of pig enterocytes, and the undifferentiated plasma membrane of cultured MA104 cells all gave qualitatively similar responses. Inhibition by a specific monoclonal antibody suggests that the active species causing carboxyfluorescein release is VP5*. Ca2+ (1 mM), but not Mg2+, inhibited the reaction. In situ solubilization of the outer capsid of trypsinized double-shelled particles changed release kinetics from sigmoidal to hyperbolic and was not inhibited by Ca2+. Our results indicate that membrane destabilization caused by trypsinized outer capsid proteins of rotavirus leads to fluorophore release. From the data presented here, a hypothetical model of the interaction of the various states of the viral particles with the membrane lipid phase is proposed. Membrane permeabilization induced by rotavirus may be related to the mechanism of entry of the virus into the host cell.

  14. Generation of large prime numbers from a sequence of previous prime numbers

    NASA Astrophysics Data System (ADS)

    Samir, Brahim Belhaouari; Rezk, Youssef A. Y.

    2012-09-01

    A prime number is co-prime with all the primes as well. This paper utilizes this fact by generating larger prime numbers based on a set of smaller prime numbers. The prime numbers are ordered and each two consecutive primes are coupled to generate their co-prime number formula extending this process larger prime sequence is established. Will the process help us produce larger prime numbers faster and more efficiently? This paper investigates the described process.

  15. Preparation and Properties of Asymmetric Large Unilamellar Vesicles: Interleaflet Coupling in Asymmetric Vesicles Is Dependent on Temperature but Not Curvature

    PubMed Central

    Cheng, Hui-Ting; London, Erwin

    2011-01-01

    Asymmetry of inner and outer leaflet lipid composition is an important characteristic of eukaryotic plasma membranes. We previously described a technique in which methyl-β-cyclodextrin-induced lipid exchange is used to prepare biological membrane-like asymmetric small unilamellar vesicles (SUVs). Here, to mimic plasma membranes more closely, we used a lipid-exchange-based method to prepare asymmetric large unilamellar vesicles (LUVs), which have less membrane curvature than SUVs. Asymmetric LUVs in which sphingomyelin (SM) or SM + 1-palmitoyl-2-oleoyl-phosphatidylcholine was exchanged into the outer leaflet of vesicles composed of 1,2-dioleoyl-phosphatidylethanolamine (DOPE) and 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS) were prepared with or without cholesterol. Approximately 80–100% replacement of outer leaflet DOPE and POPS was achieved. At room temperature, SM exchange into the outer leaflet increased the inner leaflet lipid order, suggesting significant interleaflet interaction. However, the SM-rich outer leaflet formed an ordered state, melting with a midpoint at ∼37°C. This was about the same value observed in pure SM vesicles, and was significantly higher than that observed in symmetric vesicles with the same SM content, which melted at ∼20°C. In other words, ordered state formation by outer-leaflet SM in asymmetric vesicles was not destabilized by an inner leaflet composed of DOPE and POPS. These properties suggest that the coupling between the physical states of the outer and inner leaflets in these asymmetric LUVs becomes very weak as the temperature approaches 37°C. Overall, the properties of asymmetric LUVs were very similar to those previously observed in asymmetric SUVs, indicating that they do not arise from the high membrane curvature of asymmetric SUVs. PMID:21641312

  16. Evidence against roles for phorbol binding protein Munc13-1, ADAM adaptor Eve-1, or vesicle trafficking phosphoproteins Munc18 or NSF as phospho-state-sensitive modulators of phorbol/PKC-activated Alzheimer APP ectodomain shedding.

    PubMed

    Ikin, Annat F; Causevic, Mirsada; Pedrini, Steve; Benson, Lyndsey S; Buxbaum, Joseph D; Suzuki, Toshiharu; Lovestone, Simon; Higashiyama, Shigeki; Mustelin, Tomas; Burgoyne, Robert D; Gandy, Sam

    2007-12-09

    Shedding of the Alzheimer amyloid precursor protein (APP) ectodomain can be accelerated by phorbol esters, compounds that act via protein kinase C (PKC) or through unconventional phorbol-binding proteins such as Munc13-1. We have previously demonstrated that application of phorbol esters or purified PKC potentiates budding of APP-bearing secretory vesicles at the trans-Golgi network (TGN) and toward the plasma membrane where APP becomes a substrate for enzymes responsible for shedding, known collectively as alpha-secretase(s). However, molecular identification of the presumptive "phospho-state-sensitive modulators of ectodomain shedding" (PMES) responsible for regulated shedding has been challenging. Here, we examined the effects on APP ectodomain shedding of four phorbol-sensitive proteins involved in regulation of vesicular membrane trafficking of APP: Munc13-1, Munc18, NSF, and Eve-1. Overexpression of either phorbol-sensitive wildtype Munc13-1 or phorbol-insensitive Munc13-1 H567K resulted in increased basal APP ectodomain shedding. However, in contrast to the report of Rossner et al (2004), phorbol ester-dependent APP ectodomain shedding from cells overexpressing APP and Munc13-1 wildtype was indistinguishable from that observed following application of phorbol to cells overexpressing APP and Munc13-1 H567K mutant. This pattern of similar effects on basal and stimulated APP shedding was also observed for Munc18 and NSF. Eve-1, an ADAM adaptor protein reported to be essential for PKC-regulated shedding of pro-EGF, was found to play no obvious role in regulated shedding of sAPPalpha. Our results indicate that, in the HEK293 system, Munc13-1, Munc18, NSF, and EVE-1 fail to meet essential criteria for identity as PMES for APP.

  17. Evidence against roles for phorbol binding protein Munc13-1, ADAM adaptor Eve-1, or vesicle trafficking phosphoproteins Munc18 or NSF as phospho-state-sensitive modulators of phorbol/PKC-activated Alzheimer APP ectodomain shedding

    PubMed Central

    Ikin, Annat F; Causevic, Mirsada; Pedrini, Steve; Benson, Lyndsey S; Buxbaum, Joseph D; Suzuki, Toshiharu; Lovestone, Simon; Higashiyama, Shigeki; Mustelin, Tomas; Burgoyne, Robert D; Gandy, Sam

    2007-01-01

    Background Shedding of the Alzheimer amyloid precursor protein (APP) ectodomain can be accelerated by phorbol esters, compounds that act via protein kinase C (PKC) or through unconventional phorbol-binding proteins such as Munc13-1. We have previously demonstrated that application of phorbol esters or purified PKC potentiates budding of APP-bearing secretory vesicles at the trans-Golgi network (TGN) and toward the plasma membrane where APP becomes a substrate for enzymes responsible for shedding, known collectively as α-secretase(s). However, molecular identification of the presumptive "phospho-state-sensitive modulators of ectodomain shedding" (PMES) responsible for regulated shedding has been challenging. Here, we examined the effects on APP ectodomain shedding of four phorbol-sensitive proteins involved in regulation of vesicular membrane trafficking of APP: Munc13-1, Munc18, NSF, and Eve-1. Results Overexpression of either phorbol-sensitive wildtype Munc13-1 or phorbol-insensitive Munc13-1 H567K resulted in increased basal APP ectodomain shedding. However, in contrast to the report of Roßner et al (2004), phorbol ester-dependent APP ectodomain shedding from cells overexpressing APP and Munc13-1 wildtype was indistinguishable from that observed following application of phorbol to cells overexpressing APP and Munc13-1 H567K mutant. This pattern of similar effects on basal and stimulated APP shedding was also observed for Munc18 and NSF. Eve-1, an ADAM adaptor protein reported to be essential for PKC-regulated shedding of pro-EGF, was found to play no obvious role in regulated shedding of sAPPα. Conclusion Our results indicate that, in the HEK293 system, Munc13-1, Munc18, NSF, and EVE-1 fail to meet essential criteria for identity as PMES for APP. PMID:18067682

  18. 30 CFR 947.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 947.823 Section 947.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE WASHINGTON § 947.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  19. 30 CFR 941.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 941.823 Section 941.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE SOUTH DAKOTA § 941.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  20. 30 CFR 933.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 933.823 Section 933.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE NORTH CAROLINA § 933.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  1. 30 CFR 910.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 910.823 Section 910.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE GEORGIA § 910.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  2. 30 CFR 937.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 937.823 Section 937.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE OREGON § 937.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  3. 30 CFR 912.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 912.823 Section 912.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE IDAHO § 912.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  4. 30 CFR 903.823 - Special performance standards-Operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 903.823 Section 903.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE ARIZONA § 903.823 Special performance standards—Operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, applies to any...

  5. 30 CFR 922.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 922.823 Section 922.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE MICHIGAN § 922.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  6. 30 CFR 941.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 941.823 Section 941.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE SOUTH DAKOTA § 941.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  7. 30 CFR 942.823 - Special performance standards-Operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 942.823 Section 942.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE TENNESSEE § 942.823 Special performance standards—Operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  8. 30 CFR 947.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 947.823 Section 947.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE WASHINGTON § 947.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  9. 30 CFR 921.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 921.823 Section 921.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE MASSACHUSETTS § 921.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  10. 30 CFR 922.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 922.823 Section 922.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE MICHIGAN § 922.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  11. 30 CFR 910.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 910.823 Section 910.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE GEORGIA § 910.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  12. 30 CFR 905.823 - Special performance standards-Operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 905.823 Section 905.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE CALIFORNIA § 905.823 Special performance standards—Operations on prime farmland. Part 832 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  13. 30 CFR 939.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 939.823 Section 939.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE RHODE ISLAND § 939.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  14. 30 CFR 921.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 921.823 Section 921.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE MASSACHUSETTS § 921.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  15. 30 CFR 942.823 - Special performance standards-Operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 942.823 Section 942.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE TENNESSEE § 942.823 Special performance standards—Operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  16. 30 CFR 933.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 933.823 Section 933.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE NORTH CAROLINA § 933.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  17. 30 CFR 939.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 939.823 Section 939.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE RHODE ISLAND § 939.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply...

  18. 30 CFR 937.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 937.823 Section 937.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE OREGON § 937.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  19. 30 CFR 903.823 - Special performance standards-Operations on prime farmland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... prime farmland. 903.823 Section 903.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE ARIZONA § 903.823 Special performance standards—Operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, applies to any...

  20. 30 CFR 905.823 - Special performance standards-Operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 905.823 Section 905.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE CALIFORNIA § 905.823 Special performance standards—Operations on prime farmland. Part 832 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  1. 30 CFR 912.823 - Special performance standards-operations on prime farmland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... prime farmland. 912.823 Section 912.823 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE IDAHO § 912.823 Special performance standards—operations on prime farmland. Part 823 of this chapter, Special Permanent Program Performance Standards—Operations on Prime Farmland, shall apply to any...

  2. Endocytosis is required for exocytosis and priming of respiratory burst activity in human neutrophils.

    PubMed

    Creed, T Michael; Tandon, Shweta; Ward, Richard A; McLeish, Kenneth R

    2017-06-21

    Neutrophil generation of reactive oxygen species (ROS) is enhanced by exposure to pro-inflammatory agents in a process termed priming. Priming is depending on exocytosis of neutrophil granules and p47(phox) phosphorylation-dependent translocation of cytosolic NADPH oxidase components. Clathrin-mediated endocytosis was recently reported to be necessary for priming, but the mechanism linking endocytosis to priming was not identified. The present study examined the hypothesis that endocytosis regulates neutrophil priming by controlling granule exocytosis. Clathrin-mediated endocytosis by isolated human neutrophils was inhibited by chlorpromazine, monodansylcadaverine, and sucrose. Exocytosis of granule subsets was measured as release of granule components by ELISA or chemiluminescence. ROS generation was measured as extracellular release of superoxide as reduction of ferrocytochrome c. p38 MAPK activation and p47(phox) phosphorylation were measured by immunoblot analysis. Statistical analysis was performed using a one-way ANOVA with the Tukey-Kramer multiple-comparison test. Inhibition of endocytosis prevented priming of superoxide release by TNFα and inhibited TNFα stimulation and priming of exocytosis of all four granule subsets. Inhibition of endocytosis did not reduce TNFα-stimulated p38 MAPK activation or p47(phox) phosphorylation. Inhibition of NADPH oxidase activity blocked TNFα stimulation of secretory vesicle and gelatinase granule exocytosis. Endocytosis is linked to priming of respiratory burst activity through ROS-mediated control of granule exocytosis.

  3. Primes in Fibonacci n-step and Lucas n-step Sequences

    NASA Astrophysics Data System (ADS)

    Noe, Tony D.; Vos Post, Jonathan

    2005-09-01

    We search for primes in the Fibonacci n-step and Lucas n-step sequences, which are the natural generalizations of the Fibonacci and Lucas numbers. While the Fibonacci n-step sequences are nearly devoid of primes, the Lucas n-step sequences are prime-rich. We tabulate the occurrence of primes in the first 10000 terms for n <= 100. We also state two conjectures about Diophantine equations based on these sequences.

  4. Subliminal Semantic Priming in Speech

    PubMed Central

    Tillmann, Barbara; Perrin, Fabien

    2011-01-01

    Numerous studies have reported subliminal repetition and semantic priming in the visual modality. We transferred this paradigm to the auditory modality. Prime awareness was manipulated by a reduction of sound intensity level. Uncategorized prime words (according to a post-test) were followed by semantically related, unrelated, or repeated target words (presented without intensity reduction) and participants performed a lexical decision task (LDT). Participants with slower reaction times in the LDT showed semantic priming (faster reaction times for semantically related compared to unrelated targets) and negative repetition priming (slower reaction times for repeated compared to semantically related targets). This is the first report of semantic priming in the auditory modality without conscious categorization of the prime. PMID:21655277

  5. Repetition priming: Is music special?

    PubMed

    Bigand, E; Tillmann, B; Poulin-Charronnat, B; Manderlier, D

    2005-11-01

    Using short and long contexts, the present study investigated musical priming effects that are based on chord repetition and harmonic relatedness. A musical target (a chord) was preceded by either an identical prime or a different but harmonically related prime. In contrast to words, pictures, and environmental sounds, chord processing was not facilitated by repetition. Experiments 1 and 2 using single-chord primes showed either no significant difference between chord repetition and harmonic relatedness or facilitated processing for harmonically related targets. Experiment 3 using longer prime contexts showed that musical priming depended more on the musical function of the target in the preceding context than on target repetition. The effect of musical function was decreased, but not qualitatively changed, by chord repetition. The outcome of this study challenges predictions of sensory approaches and supports a cognitive approach of musical priming.

  6. Semantic priming of familiar songs.

    PubMed

    Johnson, Sarah K; Halpern, Andrea R

    2012-05-01

    We explored the functional organization of semantic memory for music by comparing priming across familiar songs both within modalities (Experiment 1, tune to tune; Experiment 3, category label to lyrics) and across modalities (Experiment 2, category label to tune; Experiment 4, tune to lyrics). Participants judged whether or not the target tune or lyrics were real (akin to lexical decision tasks). We found significant priming, analogous to linguistic associative-priming effects, in reaction times for related primes as compared to unrelated primes, but primarily for within-modality comparisons. Reaction times to tunes (e.g., "Silent Night") were faster following related tunes ("Deck the Hall") than following unrelated tunes ("God Bless America"). However, a category label (e.g., Christmas) did not prime tunes from within that category. Lyrics were primed by a related category label, but not by a related tune. These results support the conceptual organization of music in semantic memory, but with potentially weaker associations across modalities.

  7. Vesicles of 2-ketooctanoic acid in water.

    PubMed

    Xu, Huifang; Du, Na; Song, Yawen; Song, Shue; Hou, Wanguo

    2017-03-15

    We report the spontaneous formation of vesicles from 2-ketooctanoic acid (KOCOOH), a single-tailed weakly acidic surfactant, in water. The vesicles were characterized using negative-staining, cryogenic transmission electron microscopy, conductivity, and atomic force microscopy. The pH effect on the vesicle formation and the stability of the vesicular structures were determined. The vesicles form at a very low concentration (ca. 1.4 mM) and within a wide pH range (ca. 2-10). Uni- and multilamellar vesicle structures are observed, which coexist in the KOCOOH solution. The hydrogen bonding between KOCOOH molecules probably plays an important role in the formation of the vesicles. Importantly, the vesicles exhibit remarkable stability upon long-term storage, and in artificial seawater. KOCOOH vesicles are a good alternative model system for protocell-like vesicles, as they are easily formed under plausible prebiotic conditions. In addition, they may have the same potential applications, such as in medicine, chemical engineering, and biotechnology, as conventional vesicles. To the best of our knowledge, this is the first report on the vesicles of single-tailed keto-acid amphiphiles.

  8. Rheological properties of a vesicle suspension

    NASA Astrophysics Data System (ADS)

    Guedda, M.; Benlahsen, M.; Misbah, C.

    2014-11-01

    The rheological behavior of a dilute suspension of vesicles in linear shear flow at a finite concentration is analytically examined. In the quasispherical limit, two coupled nonlinear equations that describe the vesicle orientation in the flow and its shape evolution were derived [Phys. Rev. Lett. 96, 028104 (2006), 10.1103/PhysRevLett.96.028104] and serve here as a starting point. Of special interest is to provide, for the first time, an exact analytical prediction of the time-dependent effective viscosity ηeff and normal stress differences N1 and N2. Our results shed light on the effect of the viscosity ratio λ (defined as the inner over the outer fluid viscosities) as the main controlling parameter. It is shown that ηeff,N1 , and N2 either tend to a steady state or describe a periodic time-dependent rheological response, previously reported numerically and experimentally. In particular, the shear viscosity minimum and the cusp singularities of ηeff,N1 , and N2 at the tumbling threshold are brought to light. We also report on rheology properties for an arbitrary linear flow. We were able to obtain a constitutive law in a closed form relating the stress tensor to the strain rate tensor. It is found that the resulting constitutive markedly contrasts with classical laws known for other complex fluids, such as emulsions, capsule suspensions, and dilute polymer solutions (Oldroyd B model). We highlight the main differences between our law and classical laws.

  9. Vesicle Motion during Sustained Exocytosis in Chromaffin Cells: Numerical Model Based on Amperometric Measurements

    PubMed Central

    Jarukanont, Daungruthai; Bonifas Arredondo, Imelda; Femat, Ricardo; Garcia, Martin E.

    2015-01-01

    Chromaffin cells release catecholamines by exocytosis, a process that includes vesicle docking, priming and fusion. Although all these steps have been intensively studied, some aspects of their mechanisms, particularly those regarding vesicle transport to the active sites situated at the membrane, are still unclear. In this work, we show that it is possible to extract information on vesicle motion in Chromaffin cells from the combination of Langevin simulations and amperometric measurements. We developed a numerical model based on Langevin simulations of vesicle motion towards the cell membrane and on the statistical analysis of vesicle arrival times. We also performed amperometric experiments in bovine-adrenal Chromaffin cells under Ba2+ stimulation to capture neurotransmitter releases during sustained exocytosis. In the sustained phase, each amperometric peak can be related to a single release from a new vesicle arriving at the active site. The amperometric signal can then be mapped into a spike-series of release events. We normalized the spike-series resulting from the current peaks using a time-rescaling transformation, thus making signals coming from different cells comparable. We discuss why the obtained spike-series may contain information about the motion of all vesicles leading to release of catecholamines. We show that the release statistics in our experiments considerably deviate from Poisson processes. Moreover, the interspike-time probability is reasonably well described by two-parameter gamma distributions. In order to interpret this result we computed the vesicles’ arrival statistics from our Langevin simulations. As expected, assuming purely diffusive vesicle motion we obtain Poisson statistics. However, if we assume that all vesicles are guided toward the membrane by an attractive harmonic potential, simulations also lead to gamma distributions of the interspike-time probability, in remarkably good agreement with experiment. We also show that

  10. Two primes priming: does feature integration occur before response activation?

    PubMed

    Grainger, Julianne E; Scharnowski, Frank; Schmidt, Thomas; Herzog, Michael H

    2013-07-17

    Responses to a target can be sped up or slowed down by a congruent or incongruent prime, respectively. Even though presentations are rapid, the prime and the target are thought to activate motor responses in strict sequence, with prime activation preceding target activation. In feature fusion, the opposite seems to be the case. For example, a vernier offset to the left is immediately followed by a vernier offset to the right at the same location. The two verniers are not perceived as two elements in sequence but as a single, aligned vernier. Here, we ask the question as to how features are integrated: before or after motor activation? We presented two vernier primes with opposite offset directions preceding a single vernier target. No priming effect occurred when the vernier primes were presented at the same location, indicating that verniers integrate before motor activation. There was also no priming effect when the primes were presented simultaneously at different locations, indicating that there is an integration stage different from the perceptual fusion stage. When the second prime is delayed, it determines priming, even for very long delays. To explain these long integration times, we argue that there is a buffer preceding motor activation.

  11. Hydrothermal syntheses, crystal structures and luminescence properties of zinc(II) and cadmium(II) coordination polymers based on bifunctional 3,2 Prime :6 Prime ,3 Prime Prime -terpyridine-4 Prime -carboxylic acid

    SciTech Connect

    Li, Na; Guo, Hui-Lin; Hu, Huai-Ming; Song, Juan; Xu, Bing; Yang, Meng-Lin; Dong, Fa-Xin; Xue, Gang-Lin

    2013-02-15

    Five new coordination polymers, [Zn{sub 2}(ctpy){sub 2}Cl{sub 2}]{sub n} (1), [Zn{sub 2}(ctpy){sub 2}(ox)(H{sub 2}O){sub 2}]{sub n} (2), [Zn{sub 2}(ctpy)(3-btc)(H{sub 2}O)]{sub n}{center_dot}0.5nH{sub 2}O (3), [Cd(ctpy){sub 2}(H{sub 2}O)]{sub n} (4), [Cd{sub 4}(ctpy){sub 2}(2-btc){sub 2}(H{sub 2}O){sub 2}]{sub n}{center_dot}2nH{sub 2}O (5), (Hctpy=3,2 Prime :6 Prime ,3 Prime Prime -terpyridine-4 Prime -carboxylic acid, H{sub 2}ox=oxalic acid, H{sub 3}(3-btc)=1,3,5-benzenetricarboxylic acid, H{sub 3}(2-btc)=1,2,4-benzenetricarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compounds 1-2 are a one-dimensional chain with weak interactions to form 3D supramolecular structures. Compound 3 is a 4-nodal 3D topology framework comprised of binuclear zinc units and (ctpy){sup -} anions. Compound 4 shows two dimensional net. Compound 5 is a (4,5,6)-connected framework with {l_brace}4{sup 4}{center_dot}6{sup 2}{r_brace}{l_brace}4{sup 6}{center_dot}6{sup 4}{r_brace}{sub 2}{l_brace}4{sup 9}{center_dot}6{sup 6}{r_brace} topology. In addition, the thermal stabilities and photoluminescence properties of 1-5 were also studied in the solid state. - Graphical abstract: Five new Zn/Cd compounds with 3,2 Prime :6 Prime ,3 Prime Prime -terpyridine-4 Prime -carboxylic acid were prepared. The photoluminescence and thermal stabilities properties of 1-5 were investigated in the solid state. Highlights: Black-Right-Pointing-Pointer Five new zinc/cadmium metal-organic frameworks have been hydrothermal synthesized. Black-Right-Pointing-Pointer The structural variation is attributed to the diverse metal ions and auxiliary ligand. Black-Right-Pointing-Pointer Compounds 1-5 exhibit 1D ring chain, 2D layer and 3D open-framework, respectively. Black-Right-Pointing-Pointer These compounds exhibit strong solid state luminescence emission at room temperature.

  12. Transdermal delivery of flurbiprofen from surfactant-based vesicles: particle characterization and the effect of water on in vitro transport.

    PubMed

    Uchino, Tomonobu; Matsumoto, Yuiko; Murata, Akiko; Oka, Toshihiko; Miyazaki, Yasunori; Kagawa, Yoshiyuki

    2014-04-10

    Flurbiprofen loaded rigid and elastic vesicles comprising the bilayer-forming surfactant sucrose-ester laurate were prepared by the film rehydration and extrusion method. The charge-inducing agent sodium dodecyl sulfate, and the micelle-forming surfactants, sorbitan monolaurate, polyethylene glycol monolaurate, and polysorbate 20, were used to enhance elasticity. Vesicle formulations were evaluated for size, zeta potential, (1)H and (19)F nuclear magnetic resonance (NMR) spectra, and in vitro skin permeation across Yucatan micropig (YMP) skin. Vesicle formulations were stable for 2 weeks and their mean sizes were 95-135 nm. NMR spectroscopy showed that flurbiprofen molecular mobility was restricted by interaction with vesicle components because of entrapment in vesicle bilayers. Moreover, sorbitan monolaurate-containing vesicles strongly retained flurbiprofen molecules. After non-occlusive application to YMP skin, flurbiprofen transport from all vesicle formulations was superior to that of flurbiprofen alone and remarkably decreased after water vaporization. Polarization microscopy and small-angle X-ray diffraction analysis showed that the vesicle formulation was transferred to liquid crystalline state. Suppression of vesicle transition to the liquid crystalline state was observed with applications of both large quantities and diluted samples. The presence of water in the formulations was associated with maintenance of the vesicle structure and greater flurbiprofen transport across YMP skin. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Phospholipid Vesicles in Materials Science

    SciTech Connect

    Granick, Steve

    2016-05-11

    The objective of this research was to develop the science basis needed to deploy phospholipid vesicles as functional materials in energy contexts. Specifically, we sought to: (1) Develop an integrated molecular-level understanding of what determines their dynamical shape, spatial organization, and responsiveness to complex, time-varying environments; and (2) Develop understanding of their active transportation in crowded environments, which our preliminary measurements in cells suggest may hold design principles for targeting improved energy efficiency in new materials systems. The methods to do this largely involved fluorescence imaging and other spectroscopy involving single particles, vesicles, particles, DNA, and endosomes. An unexpected importance outcome was a new method to image light-emitting diodes during actual operation using super-resolution spectroscopy.

  14. Hemifusion in Synaptic Vesicle Cycle

    PubMed Central

    Kweon, Dae-Hyuk; Kong, Byoungjae; Shin, Yeon-Kyun

    2017-01-01

    In the neuron, early neurotransmitters are released through the fusion pore prior to the complete vesicle fusion. It has been thought that the fusion pore is a gap junction-like structure made of transmembrane domains (TMDs) of soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) proteins. However, evidence has accumulated that lipid mixing occurs prior to the neurotransmitter release through the fusion pore lined predominantly with lipids. To explain these observations, the hemifusion, a membrane structure in which two bilayers are partially merged, has emerged as a key step preceding the formation of the fusion pore. Furthermore, the hemifusion appears to be the bona fide intermediate step not only for the synaptic vesicle cycle, but for a wide range of membrane remodeling processes, such as viral membrane fusion and endocytotic membrane fission. PMID:28360835

  15. Tcf15 Primes Pluripotent Cells for Differentiation

    PubMed Central

    Davies, Owen R.; Lin, Chia-Yi; Radzisheuskaya, Aliaksandra; Zhou, Xinzhi; Taube, Jessica; Blin, Guillaume; Waterhouse, Anna; Smith, Andrew J.H.; Lowell, Sally

    2013-01-01

    Summary The events that prime pluripotent cells for differentiation are not well understood. Inhibitor of DNA binding/differentiation (Id) proteins, which are inhibitors of basic helix-loop-helix (bHLH) transcription factor activity, contribute to pluripotency by blocking sequential transitions toward differentiation. Using yeast-two-hybrid screens, we have identified Id-regulated transcription factors that are expressed in embryonic stem cells (ESCs). One of these, Tcf15, is also expressed in the embryonic day 4.5 embryo and is specifically associated with a novel subpopulation of primed ESCs. An Id-resistant form of Tcf15 rapidly downregulates Nanog and accelerates somatic lineage commitment. We propose that because Tcf15 can be held in an inactive state through Id activity, it may prime pluripotent cells for entry to somatic lineages upon downregulation of Id. We also find that Tcf15 expression is dependent on fibroblast growth factor (FGF) signaling, providing an explanation for how FGF can prime for differentiation without driving cells out of the pluripotent state. PMID:23395635

  16. Methods for the physical characterization and quantification of extracellular vesicles in biological samples.

    PubMed

    Rupert, Déborah L M; Claudio, Virginia; Lässer, Cecilia; Bally, Marta

    2017-01-01

    Our body fluids contain a multitude of cell-derived vesicles, secreted by most cell types, commonly referred to as extracellular vesicles. They have attracted considerable attention for their function as intercellular communication vehicles in a broad range of physiological processes and pathological conditions. Extracellular vesicles and especially the smallest type, exosomes, have also generated a lot of excitement in view of their potential as disease biomarkers or as carriers for drug delivery. In this context, state-of-the-art techniques capable of comprehensively characterizing vesicles in biological fluids are urgently needed. This review presents the arsenal of techniques available for quantification and characterization of physical properties of extracellular vesicles, summarizes their working principles, discusses their advantages and limitations and further illustrates their implementation in extracellular vesicle research. The small size and physicochemical heterogeneity of extracellular vesicles make their physical characterization and quantification an extremely challenging task. Currently, structure, size, buoyant density, optical properties and zeta potential have most commonly been studied. The concentration of vesicles in suspension can be expressed in terms of biomolecular or particle content depending on the method at hand. In addition, common quantification methods may either provide a direct quantitative measurement of vesicle concentration or solely allow for relative comparison between samples. The combination of complementary methods capable of detecting, characterizing and quantifying extracellular vesicles at a single particle level promises to provide new exciting insights into their modes of action and to reveal the existence of vesicle subpopulations fulfilling key biological tasks. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Deciphering dead-end docking of large dense core vesicles in bovine chromaffin cells.

    PubMed

    Hugo, Sandra; Dembla, Ekta; Halimani, Mahantappa; Matti, Ulf; Rettig, Jens; Becherer, Ute

    2013-10-23

    Large dense core vesicle (LDCV) exocytosis in chromaffin cells follows a well characterized process consisting of docking, priming, and fusion. Total internal reflection fluorescence microscopy (TIRFM) studies suggest that some LDCVs, although being able to dock, are resistant to calcium-triggered release. This phenomenon termed dead-end docking has not been investigated until now. We characterized dead-end vesicles using a combination of membrane capacitance measurement and visualization of LDCVs with TIRFM. Stimulation of bovine chromaffin cells for 5 min with 6 μm free intracellular Ca2+ induced strong secretion and a large reduction of the LDCV density at the plasma membrane. Approximately 15% of the LDCVs were visible at the plasma membrane throughout experiments, indicating they were permanently docked dead-end vesicles. Overexpression of Munc18-2 or SNAP-25 reduced the fraction of dead-end vesicles. Conversely, expressing open-syntaxin increased the fraction of dead-end vesicles. These results indicate the existence of the unproductive target soluble N-ethylmaleimide-sensitive factor attachment protein receptor acceptor complex composed of 2:1 syntaxin-SNAP-25 in vivo. More importantly, they define a novel function for this acceptor complex in mediating dead-end docking.

  18. Synaptotagmin-1 and -7 Are Redundantly Essential for Maintaining the Capacity of the Readily-Releasable Pool of Synaptic Vesicles

    PubMed Central

    Burré, Jacqueline; Malenka, Robert C.; Liu, Xinran; Südhof, Thomas C.

    2015-01-01

    In forebrain neurons, Ca2+ triggers exocytosis of readily releasable vesicles by binding to synaptotagmin-1 and -7, thereby inducing fast and slow vesicle exocytosis, respectively. Loss-of-function of synaptotagmin-1 or -7 selectively impairs the fast and slow phase of release, respectively, but does not change the size of the readily-releasable pool (RRP) of vesicles as measured by stimulation of release with hypertonic sucrose, or alter the rate of vesicle priming into the RRP. Here we show, however, that simultaneous loss-of-function of both synaptotagmin-1 and -7 dramatically decreased the capacity of the RRP, again without altering the rate of vesicle priming into the RRP. Either synaptotagmin-1 or -7 was sufficient to rescue the RRP size in neurons lacking both synaptotagmin-1 and -7. Although maintenance of RRP size was Ca2+-independent, mutations in Ca2+-binding sequences of synaptotagmin-1 or synaptotagmin-7—which are contained in flexible top-loop sequences of their C2 domains—blocked the ability of these synaptotagmins to maintain the RRP size. Both synaptotagmins bound to SNARE complexes; SNARE complex binding was reduced by the top-loop mutations that impaired RRP maintenance. Thus, synaptotagmin-1 and -7 perform redundant functions in maintaining the capacity of the RRP in addition to nonredundant functions in the Ca2+ triggering of different phases of release. PMID:26437117

  19. Synaptotagmin-1 and -7 Are Redundantly Essential for Maintaining the Capacity of the Readily-Releasable Pool of Synaptic Vesicles.

    PubMed

    Bacaj, Taulant; Wu, Dick; Burré, Jacqueline; Malenka, Robert C; Liu, Xinran; Südhof, Thomas C

    2015-10-01

    In forebrain neurons, Ca(2+) triggers exocytosis of readily releasable vesicles by binding to synaptotagmin-1 and -7, thereby inducing fast and slow vesicle exocytosis, respectively. Loss-of-function of synaptotagmin-1 or -7 selectively impairs the fast and slow phase of release, respectively, but does not change the size of the readily-releasable pool (RRP) of vesicles as measured by stimulation of release with hypertonic sucrose, or alter the rate of vesicle priming into the RRP. Here we show, however, that simultaneous loss-of-function of both synaptotagmin-1 and -7 dramatically decreased the capacity of the RRP, again without altering the rate of vesicle priming into the RRP. Either synaptotagmin-1 or -7 was sufficient to rescue the RRP size in neurons lacking both synaptotagmin-1 and -7. Although maintenance of RRP size was Ca(2+)-independent, mutations in Ca(2+)-binding sequences of synaptotagmin-1 or synaptotagmin-7--which are contained in flexible top-loop sequences of their C2 domains--blocked the ability of these synaptotagmins to maintain the RRP size. Both synaptotagmins bound to SNARE complexes; SNARE complex binding was reduced by the top-loop mutations that impaired RRP maintenance. Thus, synaptotagmin-1 and -7 perform redundant functions in maintaining the capacity of the RRP in addition to nonredundant functions in the Ca(2+) triggering of different phases of release.

  20. Light scattering characterization of extruded lipid vesicles.

    PubMed

    Jin, A J; Huster, D; Gawrisch, K; Nossal, R

    1999-01-01

    By modeling extruded unilamellar lipid vesicles as thin-walled ellipsoidal shells, mathematical analysis provides simple equations which relate the mean elongation and other morphological characteristics of a vesicle population to quantities readily obtained from combined static and dynamic light scattering measurements. For SOPC vesicles extruded through a 100 nm pore-size filter into a 72.9 mM NaCl solution, the inferred elongation ratio (vesicle long axis to short axis) is approximately 3.7 +/- 0.6. When these vesicles were dialyzed into hypertonic or hypotonic solutions, this elongation ratio varied from 1 (for spherical liposomes) in strongly hypotonic solutions to greater than 6 in increasingly hypertonic solutions, beyond which abrupt morphological transformations appear. These results are quantitatively consistent with a mechanism of vesicle formation by extrusion and with the expectation that vesicle volumes change to equalize internal and external osmolarity via water flow, subject to the constraint of constant bilayer area. Our analysis also provides simplified equations to assess the effects of vesicle elongation and polydispersity on liposome parameters that are commonly required to characterize vesicle preparations for diverse applications. The implications of this study for routine light scattering characterization of extruded vesicles are discussed.

  1. Mechanical properties of vesicles. I. Coordinated analysis of osmotic swelling and lysis.

    PubMed Central

    Ertel, A; Marangoni, A G; Marsh, J; Hallett, F R; Wood, J M

    1993-01-01

    To determine how transmembrane osmotic gradients perturb the structure and dynamics of biological membranes, we examined the effects of medium dilution on the structures of osmolyte-loaded lipid vesicles. Our preparations were characterized by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR) spectroscopies. Populations of Escherichia coli phosphatidylethanolamine (PE) or dioleoylphosphatidylglycerol (DOPG) vesicles prepared by the pH jump technique were variable and polymodal in size distribution. Complex and variable structural changes occurred when PE vesicles were diluted with hypotonic buffer. Such vesicles could not be used as model systems for the analysis of membrane mechanical properties. NaCl-loaded, DOPG vesicles prepared by extrusion through 100 nm (diameter) pores were reproducible and monomodal in size distribution and unilamellar, whereas those prepared by extrusion through 200-, 400-, or 600-nm pores were variable and polymodal in size distribution and/or multilamellar. Time and pressure regimes associated with osmotic lysis of extruded vesicles were defined by monitoring release of carboxyfluorescein, a self-quenching fluorescent dye. Corresponding effects of medium dilution on vesicle structure were assessed by DLS spectroscopy. These experiments and the accompanying analysis (Hallett, F.R., J. Marsh, B.G. Nickel, and J.M. Wood. 1993. Biophys. J. 64:000-000) revealed conditions under which vesicles are expected to reside in a consistently strained state. PMID:8457668

  2. Reversed Priming Effects May Be Driven by Misperception Rather than Subliminal Processing.

    PubMed

    Sand, Anders

    2016-01-01

    A new paradigm for investigating whether a cognitive process is independent of perception was recently suggested. In the paradigm, primes are shown at an intermediate signal strength that leads to trial-to-trial and inter-individual variability in prime perception. Here, I used this paradigm and an objective measure of perception to assess the influence of prime identification responses on Stroop priming. I found that sensory states producing correct and incorrect prime identification responses were also associated with qualitatively different priming effects. Incorrect prime identification responses were associated with reversed priming effects but in contrast to previous studies, I interpret this to result from the (mis-)perception of primes rather than from a subliminal process. Furthermore, the intermediate signal strength also produced inter-individual variability in prime perception that strongly influenced priming effects: only participants who on average perceived the primes were Stroop primed. I discuss how this new paradigm, with a wide range of d' values, is more appropriate when regression analysis on inter-individual identification performance is used to investigate perception-dependent processing. The results of this study, in line with previous results, suggest that drawing conclusions about subliminal processes based on data averaged over individuals may be unwarranted.

  3. Reversed Priming Effects May Be Driven by Misperception Rather than Subliminal Processing

    PubMed Central

    Sand, Anders

    2016-01-01

    A new paradigm for investigating whether a cognitive process is independent of perception was recently suggested. In the paradigm, primes are shown at an intermediate signal strength that leads to trial-to-trial and inter-individual variability in prime perception. Here, I used this paradigm and an objective measure of perception to assess the influence of prime identification responses on Stroop priming. I found that sensory states producing correct and incorrect prime identification responses were also associated with qualitatively different priming effects. Incorrect prime identification responses were associated with reversed priming effects but in contrast to previous studies, I interpret this to result from the (mis-)perception of primes rather than from a subliminal process. Furthermore, the intermediate signal strength also produced inter-individual variability in prime perception that strongly influenced priming effects: only participants who on average perceived the primes were Stroop primed. I discuss how this new paradigm, with a wide range of d′ values, is more appropriate when regression analysis on inter-individual identification performance is used to investigate perception-dependent processing. The results of this study, in line with previous results, suggest that drawing conclusions about subliminal processes based on data averaged over individuals may be unwarranted. PMID:26925016

  4. Automaticity and Flexibility of S-R Retrieval During Priming.

    PubMed

    Tobin, Hope; Race, Elizabeth

    2017-06-13

    Learned associations between stimuli and responses (S-R associations) make important contributions to behavioral and neural priming. The current study investigated the automaticity and flexibility of these S-R associations and whether the global task context in which they occur modulates the impact of S-R retrieval on priming. Participants engaged in a semantic repetition priming task in which S-R retrieval is known to influence priming. Across participants, repetition priming occurred in global task contexts (i.e., combination of activated task sets) that either remained consistent or shifted across time. In the stable context group, the global task context at study matched that at test, whereas in the shifting context group, the global task context at study differed from that at test. Results revealed that the stability of the global task context did not affect the magnitude of S-R contributions to priming and that S-R contributions to priming were significant in both the stable and shifting context groups. These results highlight the robustness of S-R contributions to priming and indicate that S-R associations can flexibly transfer across changes in higher-level task states.

  5. Priming a new identity: self-monitoring moderates the effects of nonself primes on self-judgments and behavior.

    PubMed

    DeMarree, Kenneth G; Wheeler, S Christian; Petty, Richard E

    2005-11-01

    When a construct is primed, people often act in construct-consistent ways. Several accounts for this effect have been offered, including ideomotor theory and a social functional perspective. The authors tested an additional perspective, the Active-Self account, whereby primes can temporarily alter self-perceptions. In Study 1, non-African American participants reported feeling more aggressive on an implicit measure following an African American prime. In Study 2, participants reported feeling luckier on an implicit measure following a number 7 (vs. 13) prime. In both studies, these effects were obtained only for low self-monitors, who are more likely to change self-conceptions in response to diagnostic self-information and to use their internal states in guiding behavior. Study 3 showed that low self-monitors also show larger behavioral effects of primes.

  6. All Prime Contract Awards by State or Country, Place, and Contractor, FY 88. Part 12. (Amherst, New Hampshire-White Sands Missile Range, New Mexico).

    DTIC Science & Technology

    1988-01-01

    6w1 M.~hKCUMT ~hSD STATE OR COUNTRY minC meD In COUTTERG FY a. (U) MESNINTON HLUUAATE*S SERVICES (DOD) DC DIRECTOATE FOR INF. 19Wt DIORtSTII-N-PT-12...ORGANIZATION WHSj, Directorate for Informaticn (If applicable) Operations and Reports 6 ,’ADDRESS (City, State , and ZIPCode) 7b. ADDRESS (City, State , and...applicable) 8c. ADDRESS (City, State , and ZIP Code) 10. SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK WORK UNIT ELEMENT NO. NO. NO. ACCESSION NO. 11

  7. Alignment of synaptic vesicle macromolecules with the macromolecules in active zone material that direct vesicle docking.

    PubMed

    Harlow, Mark L; Szule, Joseph A; Xu, Jing; Jung, Jae Hoon; Marshall, Robert M; McMahan, Uel J

    2013-01-01

    Synaptic vesicles dock at active zones on the presynaptic plasma membrane of a neuron's axon terminals as a precondition for fusing with the membrane and releasing their neurotransmitter to mediate synaptic impulse transmission. Typically, docked vesicles are next to aggregates of plasma membrane-bound macromolecules called active zone material (AZM). Electron tomography on tissue sections from fixed and stained axon terminals of active and resting frog neuromuscular junctions has led to the conclusion that undocked vesicles are directed to and held at the docking sites by the successive formation of stable connections between vesicle membrane proteins and proteins in different classes of AZM macromolecules. Using the same nanometer scale 3D imaging technology on appropriately stained frog neuromuscular junctions, we found that ∼10% of a vesicle's luminal volume is occupied by a radial assembly of elongate macromolecules attached by narrow projections, nubs, to the vesicle membrane at ∼25 sites. The assembly's chiral, bilateral shape is nearly the same vesicle to vesicle, and nubs, at their sites of connection to the vesicle membrane, are linked to macromolecules that span the membrane. For docked vesicles, the orientation of the assembly's shape relative to the AZM and the presynaptic membrane is the same vesicle to vesicle, whereas for undocked vesicles it is not. The connection sites of most nubs on the membrane of docked vesicles are paired with the connection sites of the different classes of AZM macromolecules that regulate docking, and the membrane spanning macromolecules linked to these nubs are also attached to the AZM macromolecules. We conclude that the luminal assembly of macromolecules anchors in a particular arrangement vesicle membrane macromolecules, which contain the proteins that connect the vesicles to AZM macromolecules during docking. Undocked vesicles must move in a way that aligns this arrangement with the AZM macromolecules for docking

  8. On the fractal distribution of primes and prime-indexed primes by the binary image analysis

    NASA Astrophysics Data System (ADS)

    Cattani, Carlo; Ciancio, Armando

    2016-10-01

    In this paper, the distribution of primes and prime-indexed primes (PIPs) is studied by mapping primes into a binary image which visualizes the distribution of primes. These images show that the distribution of primes (and PIPs) is similar to a Cantor dust, moreover the self-similarity with respect to the order of PIPs (already proven in Batchko (2014)) can be seen as an invariance of the binary images. The index of primes plays the same role of the scale for fractals, so that with respect to the index the distribution of prime-indexed primes is characterized by the self-similarity alike any other fractal. In particular, in order to single out the scale dependence, the PIPs fractal distribution will be evaluated by limiting to two parameters, fractal dimension (δ) and lacunarity (λ), that are usually used to measure the fractal nature. Because of the invariance of the corresponding binary plots, the fractal dimension and lacunarity of primes distribution are invariant with respect to the index of PIPs.

  9. Apollo 1 Prime Crew

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Portrait of the Apollo 1 prime crew for first manned Apollo space flight. From left to right are: Edward H. White II, Virgil I. 'Gus' Grissom, and Roger B. Chaffee. On January 27, 1967 at 5:31 p.m. CST (6:31 local time) during a routine simulated launch test onboard the Apollo Saturn V Moon rocket, an electrical short circuit inside the Apollo Command Module ignited the pure oxygen environment and within a matter of seconds all three Apollo 1 crewmembers perished.

  10. Gas Vesicle Nanoparticles for Antigen Display

    PubMed Central

    DasSarma, Shiladitya; DasSarma, Priya

    2015-01-01

    Microorganisms like the halophilic archaeon Halobacterium sp. NRC-1 produce gas-filled buoyant organelles, which are easily purified as protein nanoparticles (called gas vesicles or GVNPs). GVNPs are non-toxic, exceptionally stable, bioengineerable, and self-adjuvanting. A large gene cluster encoding more than a dozen proteins has been implicated in their biogenesis. One protein, GvpC, found on the exterior surface of the nanoparticles, can accommodate insertions near the C-terminal region and results in GVNPs displaying the inserted sequences on the surface of the nanoparticles. Here, we review the current state of knowledge on GVNP structure and biogenesis as well as available studies on immunogenicity of pathogenic viral, bacterial, and eukaryotic proteins and peptides displayed on the nanoparticles. Recent improvements in genetic tools for bioengineering of GVNPs are discussed, along with future opportunities and challenges for development of vaccines and other applications. PMID:26350601

  11. Transposed-Letter Priming Effects with Masked Subset Primes: A Re-Examination of the "Relative Position Priming Constraint"

    ERIC Educational Resources Information Center

    Stinchcombe, Eric J.; Lupker, Stephen J.; Davis, Colin J.

    2012-01-01

    Three experiments are reported investigating the role of letter order in orthographic subset priming (e.g., "grdn"-GARDEN) using both the conventional masked priming technique as well as the sandwich priming technique in a lexical decision task. In all three experiments, subset primes produced priming with the effect being considerably…

  12. Transposed-Letter Priming Effects with Masked Subset Primes: A Re-Examination of the "Relative Position Priming Constraint"

    ERIC Educational Resources Information Center

    Stinchcombe, Eric J.; Lupker, Stephen J.; Davis, Colin J.

    2012-01-01

    Three experiments are reported investigating the role of letter order in orthographic subset priming (e.g., "grdn"-GARDEN) using both the conventional masked priming technique as well as the sandwich priming technique in a lexical decision task. In all three experiments, subset primes produced priming with the effect being considerably…

  13. An Introduction to Project PRIME and CAMPUS MINNESOTA. Project PRIME Report, Number 2.

    ERIC Educational Resources Information Center

    Cordes, David C.

    PRIME is an acronym for Planning Resources in Minnesota Education. The project's primary objective is to test the implementation of CAMPUS (Comprehensive Analytical Methods for Planning University Systems) in one State College, one Junior College, and in one school at the University of Minnesota. The CAMPUS model was developed by the Institute for…

  14. Ultrasound-responsive ultrathin multiblock copolyamide vesicles

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Yu, Chunyang; Huang, Tong; Xu, Shuting; Bai, Yongping; Zhou, Yongfeng

    2016-02-01

    This study reports the self-assembly of novel polymer vesicles from an amphiphilic multiblock copolyamide, and the vesicles show a special structure with an ultrathin wall thickness of about 4.5 nm and a combined bilayer and monolayer packing model. Most interestingly, the vesicles are ultrasound-responsive and can release the encapsulated model drugs in response to ultrasonic irradiation.This study reports the self-assembly of novel polymer vesicles from an amphiphilic multiblock copolyamide, and the vesicles show a special structure with an ultrathin wall thickness of about 4.5 nm and a combined bilayer and monolayer packing model. Most interestingly, the vesicles are ultrasound-responsive and can release the encapsulated model drugs in response to ultrasonic irradiation. Electronic supplementary information (ESI) available: Details of experiments and characterization, and FT-IR, TEM, DPD, FL and micro-DSC results. See DOI: 10.1039/c5nr08596a

  15. Extrasynaptic vesicle recycling in mature hippocampal neurons.

    PubMed

    Ratnayaka, Arjuna; Marra, Vincenzo; Branco, Tiago; Staras, Kevin

    2011-11-08

    Fast neuronal signalling relies on highly regulated vesicle fusion and recycling at specialized presynaptic terminals. Recently, examples of non-classical neurotransmission have also been reported, where fusion of vesicles can occur at sites remote from conventional synapses. This has potentially broad biological implications, but the underlying mechanisms are not well established. Here we show that a complete vesicle recycling pathway can occur at discrete axonal sites in mature hippocampal neurons and that extrasynaptic fusion is a robust feature of native tissue. We demonstrate that laterally mobile vesicle clusters trafficking between synaptic terminals become transiently stabilized by evoked action potentials and undergo complete but delayed Ca(2+)-dependent fusion along axons. This fusion is associated with dynamic actin accumulation and, subsequently, vesicles can be locally recycled, re-acidified and re-used. Immunofluorescence and ultrastructural work demonstrates that extrasynaptic fusion sites can have apposed postsynaptic specializations, suggesting that mobile vesicle recycling may underlie highly dynamic neuron-neuron communication.

  16. Polyaspartamide Vesicle induced by Metallic Nanoparticles.

    PubMed

    Jeong, Jae Hyun; Cha, Chaenyung; Kaczmarowski, Amy; Haan, John; Oh, Soonnam; Kong, Hyunjoon

    2012-01-09

    Polymer vesicles are being extensively studied to emulate self-assembly in biological systems and also use them in a variety of biological and industrial applications. This study demonstrates a novel strategy to prepare polymer vesicles in a pure aqueous medium by driving the micelle-to-vesicle transition with metallic nanoparticles. We synthesized poly(2-amino-2-hydroxyethyl aspartamide) (PAHA) substituted with octadecyl chains, which could form micelle-like self-aggregates in the aqueous medium and chemically bind with platinum precursors. Then, in situ polymerization of Pt nanoparticles within the PAHA self-aggregates generated polymer vesicles that possess nanoparticles within bilayers, because of the increase of the hydrophilic mass ratio to total mass of PAHA, f (w). This new strategy to prepare polymer vesicles would greatly serve to facilitate the control of self-assembly and ultimately improve the functionality of a wide array of polymer vesicles.

  17. Optogenetic Acidification of Synaptic Vesicles and Lysosomes

    PubMed Central

    Grauel, M. Katharina; Wozny, Christian; Bentz, Claudia; Blessing, Anja; Rosenmund, Tanja; Jentsch, Thomas J.; Schmitz, Dietmar; Hegemann, Peter; Rosenmund, Christian

    2016-01-01

    Acidification is required for the function of many intracellular organelles, but methods to acutely manipulate their intraluminal pH have not been available. Here we present a targeting strategy to selectively express the light-driven proton pump Arch3 on synaptic vesicles. Our new tool, pHoenix, can functionally replace endogenous proton pumps, enabling optogenetic control of vesicular acidification and neurotransmitter accumulation. Under physiological conditions, glutamatergic vesicles are nearly full, as additional vesicle acidification with pHoenix only slightly increased the quantal size. By contrast, we found that incompletely filled vesicles exhibited a lower release probability than full vesicles, suggesting preferential exocytosis of vesicles with high transmitter content. Our subcellular targeting approach can be transferred to other organelles, as demonstrated for a pHoenix variant that allows light-activated acidification of lysosomes. PMID:26551543

  18. Neuroimaging correlates of negative priming.

    PubMed

    Steel, C; Haworth, E J; Peters, E; Hemsley, D R; Sharma, T; Gray, J A; Pickering, A; Gregory, L; Simmons, A; Bullmore, E T; Williams, S C

    2001-11-16

    Many theoretical accounts of selective attention and memory retrieval include reference to active inhibitory processes, such as those argued to underlie the negative priming effect. fMRI was used in order to investigate the areas of cortical activation associated with Stroop interference, Stroop facilitation and Stroop negative priming tasks. The most significant activation within the negative priming task was within the inferior parietal lobule, left temporal lobe and frontal lobes. Areas of cortical activation are discussed with reference to theoretical accounts of the negative priming effect.

  19. Prime mover progress

    SciTech Connect

    Hennagir, T.

    1995-05-01

    Manufacturers continue to upgrade fluidized bed and steam technologies to meet more stringent emission, efficiency and service challenges from global power market customers. Offshore, suppliers are being pushed to provide quality, low-cost production and significant local competitive presence in nearly all international markets. The ability to meet customer and regulatory demands for emissions across different global market segments remains a priority for prime mover suppliers as they develop environmental technical improvements. Products initially developed for the more stringent European regulations are now finding a market in the US. In developing countries, demand continues for utility-size boiler products, but pollution control equipment costs remain a parallel consideration. Industry improvements to steam cycle equipment, namely turbines, continue to reap benefits in terms of efficiency and operational flexibility. Boiler and steam manufacturers` response to global markets remains right on target as product development strategies are constantly adjusted and analyzed to reach an optimum marketing mix. Innovation and advances in prime mover power equipment technology remain a mainstay of suppliers` ability to meet the needs of a changing, competitive clientele.

  20. Autonomous movement of a chemically powered vesicle

    NASA Astrophysics Data System (ADS)

    Gupta, Shivam; Sreeja, K. K.; Thakur, Snigdha

    2015-10-01

    We investigate the diffusio-phoretic motion of a deformable vesicle. A vesicle is built from the linked catalytic and noncatalytic vertices that consumes fuel in the environment and utilize the resulting self-generated concentration gradient to exhibit propulsive motion. Under nonequilibrium conditions it is found that the self-propulsion velocity of the vesicle depends on its shape, which in turn is controlled by the bending rigidity of the membrane and solvent density around it. The self-propulsion velocity of the vesicle for different shapes has been calculated and the factors which affect the velocity are identified.

  1. Trafficking of astrocytic vesicles in hippocampal slices

    SciTech Connect

    Potokar, Maja; Kreft, Marko; Lee, So-Young; Takano, Hajime; Haydon, Philip G.; Zorec, Robert

    2009-12-25

    The increasingly appreciated role of astrocytes in neurophysiology dictates a thorough understanding of the mechanisms underlying the communication between astrocytes and neurons. In particular, the uptake and release of signaling substances into/from astrocytes is considered as crucial. The release of different gliotransmitters involves regulated exocytosis, consisting of the fusion between the vesicle and the plasma membranes. After fusion with the plasma membrane vesicles may be retrieved into the cytoplasm and may continue to recycle. To study the mobility implicated in the retrieval of secretory vesicles, these structures have been previously efficiently and specifically labeled in cultured astrocytes, by exposing live cells to primary and secondary antibodies. Since the vesicle labeling and the vesicle mobility properties may be an artifact of cell culture conditions, we here asked whether the retrieving exocytotic vesicles can be labeled in brain tissue slices and whether their mobility differs to that observed in cell cultures. We labeled astrocytic vesicles and recorded their mobility with two-photon microscopy in hippocampal slices from transgenic mice with fluorescently tagged astrocytes (GFP mice) and in wild-type mice with astrocytes labeled by Fluo4 fluorescence indicator. Glutamatergic vesicles and peptidergic granules were labeled by the anti-vesicular glutamate transporter 1 (vGlut1) and anti-atrial natriuretic peptide (ANP) antibodies, respectively. We report that the vesicle mobility parameters (velocity, maximal displacement and track length) recorded in astrocytes from tissue slices are similar to those reported previously in cultured astrocytes.

  2. Non-D Anti-D Decays of the psi-prime-prime (3770)

    SciTech Connect

    Majid, W.A.

    2004-06-02

    A search for inclusive non-D{bar B} decays of the {Psi}{double_prime}(3770) is performed in a sample of 9.56 {+-} 0.48 pb{sup -1} collected by the Mark III detector at the SPEAR storage ring, at the Stanford Linear Accelerator Center. To be more specific, a search for inclusive {bar p}, {bar {Lambda}}, and {phi} decay modes of the {Psi}{double_prime}(3770) is performed in this data sample. Backgrounds due to the decays of the radiatively produced {Psi}{prime}(3686) are subtracted. Also backgrounds due to the production of the same final state by nonresonant e{sup +}e{sup -} annihilation are subtracted. After further background subtractions from D meson decays and particle misidentification and efficiency corrections no events are seen and upper limits are placed for each one of these decay channels.

  3. Alignment of Synaptic Vesicle Macromolecules with the Macromolecules in Active Zone Material that Direct Vesicle Docking

    PubMed Central

    Xu, Jing; Jung, Jae Hoon; Marshall, Robert M.; McMahan, Uel J.

    2013-01-01

    Synaptic vesicles dock at active zones on the presynaptic plasma membrane of a neuron’s axon terminals as a precondition for fusing with the membrane and releasing their neurotransmitter to mediate synaptic impulse transmission. Typically, docked vesicles are next to aggregates of plasma membrane-bound macromolecules called active zone material (AZM). Electron tomography on tissue sections from fixed and stained axon terminals of active and resting frog neuromuscular junctions has led to the conclusion that undocked vesicles are directed to and held at the docking sites by the successive formation of stable connections between vesicle membrane proteins and proteins in different classes of AZM macromolecules. Using the same nanometer scale 3D imaging technology on appropriately stained frog neuromuscular junctions, we found that ∼10% of a vesicle’s luminal volume is occupied by a radial assembly of elongate macromolecules attached by narrow projections, nubs, to the vesicle membrane at ∼25 sites. The assembly’s chiral, bilateral shape is nearly the same vesicle to vesicle, and nubs, at their sites of connection to the vesicle membrane, are linked to macromolecules that span the membrane. For docked vesicles, the orientation of the assembly’s shape relative to the AZM and the presynaptic membrane is the same vesicle to vesicle, whereas for undocked vesicles it is not. The connection sites of most nubs on the membrane of docked vesicles are paired with the connection sites of the different classes of AZM macromolecules that regulate docking, and the membrane spanning macromolecules linked to these nubs are also attached to the AZM macromolecules. We conclude that the luminal assembly of macromolecules anchors in a particular arrangement vesicle membrane macromolecules, which contain the proteins that connect the vesicles to AZM macromolecules during docking. Undocked vesicles must move in a way that aligns this arrangement with the AZM macromolecules for

  4. Investigating Home Primes and Their Families

    ERIC Educational Resources Information Center

    Herman, Marlena; Schiffman, Jay

    2014-01-01

    The process of prime factor splicing to generate home primes raises opportunity for conjecture and exploration. The notion of "home primes" is relatively new in the chronicle of mathematics. Heleen (1996-97) first described a procedure called "prime factor splicing" (PFS). The exploration of home primes is interesting and…

  5. Investigating Home Primes and Their Families

    ERIC Educational Resources Information Center

    Herman, Marlena; Schiffman, Jay

    2014-01-01

    The process of prime factor splicing to generate home primes raises opportunity for conjecture and exploration. The notion of "home primes" is relatively new in the chronicle of mathematics. Heleen (1996-97) first described a procedure called "prime factor splicing" (PFS). The exploration of home primes is interesting and…

  6. Individual Vesicle Fusion Events Mediated by Lipid-Anchored DNA

    PubMed Central

    van Lengerich, Bettina; Rawle, Robert J.; Bendix, Poul Martin; Boxer, Steven G.

    2013-01-01

    Membrane fusion consists of a complex rearrangement of lipids and proteins that results in the merger of two lipid bilayers. We have developed a model system that employs synthetic DNA-lipid conjugates as a surrogate for the membrane proteins involved in the biological fusion reaction. We previously showed that complementary DNA-lipids, inserted into small unilamellar vesicles, can mediate membrane fusion in bulk. Here, we use a model membrane architecture developed in our lab to directly observe single-vesicle fusion events using fluorescence microscopy. In this system, a planar tethered membrane patch serves as the target membrane for incoming vesicles. This allows us to quantify the kinetics and characteristics of individual fusion events from the perspective of the lipids or the DNA-lipids involved in the process. We find that the fusion pathways are heterogeneous, with an arrested hemi-fusion state predominating, and we quantitate the outcome and rate of fusion events to construct a mechanistic model of DNA-mediated vesicle fusion. The waiting times between docking and fusion are distributed exponentially, suggesting that fusion occurs in a single step. Our analysis indicates that when two lipid bilayers are brought into close proximity, fusion occurs spontaneously, with little or no dependence on the number of DNA hybrids formed. PMID:23870262

  7. Urinary extracellular vesicles and the kidney: biomarkers and beyond.

    PubMed

    Salih, Mahdi; Zietse, Robert; Hoorn, Ewout J

    2014-06-01

    Extracellular vesicles have been isolated in various body fluids, including urine. The cargo of urinary extracellular vesicles (uEVs) is composed of proteins and nucleic acids reflecting the physiological and possibly pathophysiological state of cells lining the nephron. Because urine is a noninvasive and readily available biofluid, the discovery of uEVs has opened a new field of biomarker research. Their potential use as diagnostic, prognostic, or therapeutic biomarkers for various kidney diseases, including glomerulonephritis, acute kidney injury, tubular disorders, and polycystic kidney disease, is currently being explored. Some challenges, however, remain. These challenges include the need to standardize isolation methods, normalization between samples, and validation of candidate biomarkers. Also, the development of a high-throughput platform to isolate and analyze uEVs, for example, an enzyme-linked immunosorbent assay, is desirable. Here, we review recent studies on uEVs dealing with kidney physiology and pathophysiology. Furthermore, we discuss new and exciting developments regarding vesicles, including their role in cell-to-cell communication and the possibility of using vesicles as a therapy for kidney disorders.

  8. 5[prime] to 3[prime] nucleic acid synthesis using 3[prime]-photoremovable protecting group

    DOEpatents

    Pirrung, M.C.; Shuey, S.W.; Bradley, J.C.

    1999-06-01

    The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5[prime] to 3[prime] nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5[prime] end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

  9. Phase transition in a stochastic prime-number generator.

    PubMed

    Luque, Bartolo; Lacasa, Lucas; Miramontes, Octavio

    2007-07-01

    We introduce a stochastic algorithm that acts as a prime-number generator. The dynamics of this algorithm gives rise to a continuous phase transition, which separates a phase where the algorithm is able to reduce a whole set of integers into primes and a phase where the system reaches a frozen state with low prime density. We present both numerical simulations and an analytical approach in terms of an annealed approximation, by means of which the data are collapsed. A critical slowing-down phenomenon is also outlined.

  10. Attention to primes modulates affective priming of pronunciation responses.

    PubMed

    De Houwer, Jan; Randell, Tom

    2002-01-01

    In studies on affective priming of pronunciation responses, two words are presented on each trial and participants are asked to read the second word out loud. Whereas some studies revealed shorter reaction times when the two words had the same valence than when they had a different valence, other studies either found no effect of affective congruence or revealed a reversed effect. In the present experiments, a significant effect of affective congruence only emerged when filler trials were presented in which the prime and target were identical and participants were instructed to attend to the primes (Experiment 2). No effects were found when participants were merely instructed to attend to or ignore the primes (Experiment 1), or when affectively incongruent filler trials were presented and participants were instructed to ignore the primes (Experiment 2).

  11. Microinjection into giant vesicles and light microscopy investigation of enzyme-mediated vesicle transformations.

    PubMed

    Wick, R; Angelova, M I; Walde, P; Luisi, P L

    1996-02-01

    'Giant vesicles' have diameters of several micrometers and can be observed by light microscopy. Their size may allow manipulation of individual vesicles and direct observation of the progress of a chemical reaction in real time. We set out to test this possibility using enzymatic hydrolysis of vesicle components as a model system. We describe a novel micromanipulation technique that allows us to microinject femtoliter amounts of a reagent solution adjacent to or into giant vesicles with diameters ranging from 10 to 60 microm. The vesicle transformations can be monitored directly in real time by light microscopy and recorded by video analysis. Snake venom phospholipase A2 was added to vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine, and the enzymatic hydrolysis of components of the lipid bilayer was observed over time. A specific effect on the targeted giant vesicle was seen and video recorded, while the neighbouring vesicles remained unaffected. Addition of the enzyme to the outside of a vesicle caused it to burst, whereas injection of the enzyme inside a vesicle resulted in a slow and constant decrease in its size, until it eventually disappeared from the resolution power of the light microscope. These results show that it is possible to micromanipulate an individual vesicle, and to follow visually the progress of an enzymatic reaction occurring on the vesicle bilayer over time.

  12. Construction of macroscopic cytomimetic vesicle aggregates based on click chemistry: controllable vesicle fusion and phase separation.

    PubMed

    Jin, Haibao; Huang, Wei; Zheng, Yongli; Zhou, Yongfeng; Yan, Deyue

    2012-07-09

    Vesicle-vesicle aggregation to mimic cell-cell aggregation has attracted much attention. Here, hyperbranched polymer vesicles (branched-polymersomes, BPs) with a cell-like size were selected as model membranes, and the vesicle aggregation process, triggered by click chemistry of the copper-catalysed azide-alkyne cycloaddition reaction, was systematically studied. For this purpose, azide and alkynyl groups were loaded on the membranes of BPs through the co-assembly method to obtain N(3)-BPs and Alk-BPs, respectively. Subsequently, macroscopic vesicle aggregates were obtained when these two kinds of functional BPs were mixed together with the ratio of azide to alkynyl groups of about 1:1. Both the vesicle fusion events and lateral phase separation on the vesicle membrane occurred during such a vesicle aggregation process, and the fusion rate and phase-separation degree could be controlled by adjusting the clickable group content. The vesicle aggregation process with N(3) -micelles as desmosome mimics to connect with Alk-BPs through click-chemistry reaction was also studied, and large-scale vesicle aggregates without vesicle fusion were obtained in this process. The present work has extended the controllable cytomimetic vesicle aggregation process with the use of covalent bonds, instead of noncovalent bonds, as the driving force.

  13. The role of vesicles in the transport of ferritin through frog endothelium.

    PubMed Central

    Clough, G; Michel, C C

    1981-01-01

    1. The transport of ferritin molecules by endothelial cell vesicles has been quantitatively investigated by electron microscopy. Single mesenteric capillaries of pithed frogs were perfused with solutions containing 6.7 g ferritin 100 ml.-1 for known periods before fixation in situ with osmium tetroxide. 2. Two series of experiments were carried out: in the first series the perfusate contained bovine serum albumin (1.0 g 100 ml.-1); in the second series the perfusate contained no protein other than the ferritin. To assess the molecular radius of ferritin in solution, the free diffusion coefficient of ferritin was measured in the presence and absence of albumin. 3. The free diffusion coefficient of ferritin in saline solution (110 m-mole 1.-1) was found to be 0.35 X 10(-6) cm2 sec-1 at 21 degrees C and was not affected by the presence of bovine serum albumin. This indicates that there is no significant binding of albumin to ferritin in solution and yields a value for the Stokes-Einstein radius of ferritin of 6.1 nm. 4. In all perfusion experiments the percentage of luminal vesicles containing ferritin exceeded the percentage of labelled cytoplasmic vesicles, which in turn exceeded the percentage of labelled abluminal vesicles. 5. Labelling of all vesicle populations was seen after perfusions lasting less than 1 sec. At this time luminal vesicles were more heavily labelled in the absence of albumin. 6. The labelling of luminal vesicles increased with lengthening perfusion times up to 30-40 sec, after which steady levels of labelling were achieved. The rate of rise in luminal labelling and the steady-state levels reached were both greater in the absence of albumin. By contrast cytoplasmic labelling increased above its initial value only after perfusions of longer than 10 sec. 7. In the steady state, labelled cytoplasmic vesicles contained, on average, fewer ferritin molecules than labelled luminal vesicles. This finding is inconsistent with translocation of labelled

  14. Dielectrophoresis of Functional Phospholipid Vesicles

    NASA Astrophysics Data System (ADS)

    Froude, Victoria; Zhu, Yingxi Elaine

    2008-03-01

    Recently, there has been an emerging interest in using AC-dielectrophoresis (DEP) to transport and assemble phospholipid vesicles (liposomes) and nanoparticles to form functional bio-assemblies where the underlying charge polarization mechanism of colloids in AC fields strongly depends on nano-scaled surface charge. In this work, we study liposomes segregation and aggregation in the presence of nanocolloids and salts in which the biological functionality of liposomes is augmented by the physical functionality of inorganic coating and particles. Liposomes, synthesized by sonication with 1,2-Dioleoyl-sn-Glycero-3-Phosphate (DOPA), are manipulated at varied AC-field frequencies across fabricated micro-electrodes in a quadrapole configuration on glass. We observe the co-assembly of liposome and opposite-charged nanocolloids by confocal microscopy and SEM, where the smaller nanocolloids are captured in between liposome junctions to form stabilized composite vesicles at several distinct frequencies. We observe a strong dependence of the liposome DEP mobility on the number of nanoparticles present in suspension and propose a new mechanism based on charge segregation and charged nanocolloid entrainment in the double layer.

  15. Vesicles protect activated acetic acid.

    PubMed

    Todd, Zoe R; House, Christopher H

    2014-10-01

    Abstract Methyl thioacetate, or activated acetic acid, has been proposed to be central to the origin of life and an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about 3 orders of magnitude faster (K=0.00663 s(-1); 100°C, pH 7.5, concentration=0.33 mM) than published rates for its catalyzed production, making it unlikely to accumulate under prebiotic conditions. However, our experiments showed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. Further, we found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid vesicles. Thus, the hydrophobic regions of prebiotic vesicles and early cell membranes could have offered a refuge for this energetic molecule, increasing its lifetime in close proximity to the reactions for which it would be needed. This model of early energy storage evokes an additional critical function for the earliest cell membranes.

  16. The 24th mersenne prime.

    PubMed

    Tuckerman, B

    1971-10-01

    The 24th Mersenne prime M(p) = 2(p) - 1, and currently the largest known prime, is 2(19937) - 1. Primality was shown by the Lucas-Lehmer test on an IBM 360/91 computer. The 24th even perfect number is (2(19937) - 1).2(19936).

  17. Representing Numbers: Prime and Irrational

    ERIC Educational Resources Information Center

    Zazkis, Rina

    2005-01-01

    This article draws an analogy between prime and irrational numbers with respect to how these numbers are defined and how they are perceived by learners. Excerpts are presented from two research studies: a study on understanding prime numbers by pre-service elementary school teachers and a study on understanding irrational numbers by pre-service…

  18. Priming Macho Attitudes and Emotions.

    ERIC Educational Resources Information Center

    Beaver, Erik D.; And Others

    1992-01-01

    Investigated the effects of reading one of four priming stimuli stories (control, consenting sex, rape, or family) on males' evaluations of, and emotional reactions to, two videotaped date-rape scenarios. Results supported the concepts of a macho personality and revealed interactive effects for both the rape and family prime. (RJM)

  19. The 24th Mersenne Prime

    PubMed Central

    Tuckerman, Bryant

    1971-01-01

    The 24th Mersenne prime Mp = 2p - 1, and currently the largest known prime, is 219937 - 1. Primality was shown by the Lucas-Lehmer test on an IBM 360/91 computer. The 24th even perfect number is (219937 - 1)·219936. PMID:16591945

  20. Proteomics of extracellular vesicles: Exosomes and ectosomes.

    PubMed

    Choi, Dong-Sic; Kim, Dae-Kyum; Kim, Yoon-Keun; Gho, Yong Song

    2015-01-01

    Almost all bacteria, archaea, and eukaryotic cells shed extracellular vesicles either constitutively or in a regulated manner. These nanosized membrane vesicles are spherical, bilayered proteolipids that harbor specific subsets of proteins, DNAs, RNAs, and lipids. Recent research has facilitated conceptual advancements in this emerging field that indicate that extracellular vesicles act as intercellular communicasomes by transferring signals to their target cell via surface ligands and delivering receptors and functional molecules. Recent progress in mass spectrometry-based proteomic analyses of mammalian extracellular vesicles derived from diverse cell types and body fluids has resulted in the identification of several thousand vesicular proteins that provide us with essential clues to the molecular mechanisms involved in vesicle cargo sorting and biogenesis. Furthermore, cell-type- or disease-specific vesicular proteins help us to understand the pathophysiological functions of extracellular vesicles and contribute to the discovery of diagnostic and therapeutic target proteins. This review focuses on the high-throughput mass spectrometry-based proteomic analyses of mammalian extracellular vesicles (i.e., exosomes and ectosomes), EVpedia (a free web-based integrated database of high-throughput data for systematic analyses of extracellular vesicles; http://evpedia.info), and the intravesicular protein-protein interaction network analyses of mammalian extracellular vesicles. The goal of this article is to encourage further studies to construct a comprehensive proteome database for extracellular vesicles that will help us to not only decode the biogenesis and cargo-sorting mechanisms during vesicle formation but also elucidate the pathophysiological roles of these complex extracellular organelles.

  1. Transgenerational Defense Priming for Crop Protection against Plant Pathogens: A Hypothesis.

    PubMed

    Ramírez-Carrasco, Gabriela; Martínez-Aguilar, Keren; Alvarez-Venegas, Raúl

    2017-01-01

    Throughout evolution, plants have developed diverse mechanisms of defense that "prime" their innate immune system for more robust and active induction of defense responses against different types of stress. Nowadays there are numerous reports concerning the molecular bases of priming, as well as the generational priming mechanisms. Information concerning transgenerational priming, however, remains deficient. Some reports have indicated, nonetheless, that the priming status of a plant can be inherited to its offspring. Here, we show that the priming agent β-aminobutyric acid induced resistance to Pseudomonas syringae pv. phaseolicola infection in the common bean (Phaseolus vulgaris L.) We have analyzed the transgenerational patterns of gene expression of the PvPR1 gene (Phaseolus vulgaris PR1), a highly responsive gene to priming, and show that a transgenerational priming response against pathogen attack can last for at least two generations. We hypothesize that a defense-resistant phenotype and easily identifiable, generational and transgenerational, "primed patterns" of gene expression are excellent indicators of the priming response in crop plants. Furthermore, we propose here that modern plant breeding methods and crop improvement efforts must include the use of elicitors to prime induced resistance in the field and, above all, to select for induced heritable states in progeny that is primed for defense.

  2. Exodus: Prime Mover

    NASA Technical Reports Server (NTRS)

    Bauer, Nikkol; Conwell, Pete; Johnson, Matt; Shields, Wendy; Thornton, Tim; Tokarz, Rob; Mcmanus, Rich

    1992-01-01

    The Exodus Prime Mover is an overnight package delivery aircraft designed to serve the Northern Hemisphere of Aeroworld. The preliminary design goals originated from the desire to produce a large profit. The two main driving forces throughout the design process were first to reduce the construction man-hours by simplifying the aircraft design, thereby decreasing the total production cost of the aircraft. The second influential factor affecting the design was minimizing the fuel cost during cruise. The lowest fuel consumption occurs at a cruise velocity of 30 ft/s. Overall, it was necessary to balance the economic benefits with the performance characteristics in order to create a profitable product that meets all specified requirements and objectives.

  3. Priming the Physician Pipeline: A Regional AHEC's Use of in-state Medical School Data to Guide Its Health Careers Programming.

    PubMed

    Gross, David A; Mattox, Lainey C; Winkleman, Nicole

    2016-01-01

    Amid evidence of its rural, Appalachian students' low application and matriculation rates to in-state medical schools, the Northeast Kentucky Area Health Education Center developed two physician pipeline programs. This report describes the programs' early successes and provides a basis for heightened regional responsibility in the recruitment of medical school applicants.

  4. Small Angle Neutron-Scattering Studies of the Core Structure of Intact Neurosecretory Vesicles.

    NASA Astrophysics Data System (ADS)

    Krueger, Susan Takacs

    Small angle neutron scattering (SANS) was used to study the state of the dense cores within intact neurosecretory vesicles. These vesicles transport the neurophysin proteins, along with their associated hormones, oxytocin or vasopressin, from the posterior pituitary gland to the bloodstream, where the entire vesicle contents are released. Knowledge of the vesicle core structure is important in developing an understanding of this release mechanism. Since the core constituents exist in a dense state at concentrations which cannot be reproduced (in solution) in the laboratory, a new method was developed to determine the core structure from SANS experiments performed on intact neurosecretory vesicles. These studies were complemented by biochemical assays performed to determine the role, if any, played by phospholipids in the interactions between the core constituents. H_2O/D_2 O ratio in the solvent can be adjusted, using the method of contrast variation, such that the scattering due to the vesicle membranes is minimized, thus emphasizing the scattering originating from the cores. The applicability of this method for examining the interior of biological vesicles was tested by performing an initial study on human red blood cells, which are similar in structure to other biological vesicles. Changes in intermolecular hemoglobin interactions, occurring when the ionic strength of the solvent was varied or when the cells were deoxygenated, were examined. The results agreed with those expected for dense protein solutions, indicating that the method developed was suitable for the study of hemoglobin within the cells. Similar SANS studies were then performed on intact neurosecretory vesicles. The experimental results were inconsistent with model calculations which assumed that the cores consisted of small, densely-packed particles or large, globular aggregates. Although a unique model could not be determined, the data suggest that the core constituents form long aggregates of

  5. Morphological variation of a lipid vesicle confined in a spherical vesicle

    NASA Astrophysics Data System (ADS)

    Sakashita, Ai; Imai, Masayuki; Noguchi, Hiroshi

    2014-04-01

    Morphologies of a double-bilayer vesicle were explored experimentally by fast confocal laser microscopy and numerically by a dynamically triangulated membrane model with area-difference elasticity. The confinement was found to induce several shapes of the inner vesicles that had not been observed in unilamellar vesicles: double and quadruple stomatocytes, slit vesicle, and vesicles of two or three compartments with various shapes. The simulations reproduced the experimental results very well and some of the shape transitions can be understood by a simple theoretical model for axisymmetric shapes.

  6. Self-assembled carbohydrate-based vesicles for lectin targeting.

    PubMed

    Dos Santos, Marinalva Cardoso; Micheletto, Yasmine Miguel Serafini; da Silveira, Nadya Pesce; da Silva Pinto, Luciano; Giacomelli, Fernando Carlos; de Lima, Vânia Rodrigues; Frizon, Tiago Elias Allievi; Dal-Bó, Alexandre Gonçalves

    2016-12-01

    This study examined the physicochemical interactions between vesicles formed by phosphatidylcholine (PC) and glycosylated polymeric amphiphile N-acetyl-β-d-glucosaminyl-PEG900-docosanate (C22PEG900GlcNAc) conjugated with Bauhinia variegata lectin (BVL). Lectins are proteins or glycoproteins capable of binding glycosylated membrane components. Accordingly, the surface functionalization by such entities is considered a potential strategy for targeted drug delivery. We observed increased hydrodynamic radii (RH) of PC+C22PEG900GlcNAc vesicles in the presence of lectins, suggesting that this aggregation was due to the interaction between lectins and the vesicular glycosylated surfaces. Furthermore, changes in the zeta potential of the vesicles with increasing lectin concentrations implied that the vesicular glycosylated surfaces were recognized by the investigated lectin. The presence of carbohydrate residues on vesicle surfaces and the ability of the vesicles to establish specific interactions with BVL were further explored using atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) analysis. The results indicated that the thickness of the hydrophilic layer was to some extent influenced by the presence of lectins. The presence of lectins required a higher degree of polydispersity as indicated by the width parameter of the log-normal distribution of size, which also suggested more irregular structures. Reflectance Fourier transform infrared (HATR-FTIR), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-vis.) analyses revealed that the studied lectin preferentially interacted with the choline and carbonyl groups of the lipid, thereby changing the choline orientation and intermolecular interactions. The protein also discretely reduced the intermolecular communication of the hydrophobic acyl chains, resulting in a disordered state.

  7. Functional Advantages of Porphyromonas gingivalis Vesicles

    PubMed Central

    Ho, Meng-Hsuan; Chen, Chin-Ho; Goodwin, J. Shawn; Wang, Bing-Yan; Xie, Hua

    2015-01-01

    Porphyromonas gingivalis is a keystone pathogen of periodontitis. Outer membrane vesicles (OMVs) have been considered as both offense and defense components of this bacterium. Previous studies indicated that like their originating cells, P. gingivalis vesicles, are able to invade oral epithelial cells and gingival fibroblasts, in order to promote aggregation of some specific oral bacteria and to induce host immune responses. In the present study, we investigated the invasive efficiency of P. gingivalis OMVs and compared results with that of the originating cells. Results revealed that 70–90% of human primary oral epithelial cells, gingival fibroblasts, and human umbilical vein endothelial cells carried vesicles from P. gingivalis 33277 after being exposed to the vesicles for 1 h, while 20–50% of the host cells had internalized P. gingivalis cells. We also detected vesicle-associated DNA and RNA and a vesicle-mediated horizontal gene transfer in P. gingivalis strains, which represents a novel mechanism for gene transfer between P. gingivalis strains. Moreover, purified vesicles of P. gingivalis appear to have a negative impact on biofilm formation and the maintenance of Streptococcus gordonii. Our results suggest that vesicles are likely the best offence weapon of P. gingivalis for bacterial survival in the oral cavity and for induction of periodontitis. PMID:25897780

  8. Dynamical simulations of vesicle growth and division

    NASA Astrophysics Data System (ADS)

    Ruiz-Herrero, Teresa; Mahadevan, L.

    2015-03-01

    Prebiotic cells constitute a beautiful and intriguing example of self-replicating vesicles. How these cells managed to grow and divide without sophisticated machinery is still an open question. The properties of these primitive vesicles can shed light on the ways modern cells have evolved by exploiting those characteristics to develop their replication mechanisms. The equilibrium configurations of elastic shells are well understood, however the dynamical behavior during growth still lacks of a deep theoretical understanding. To study vesicle growth from a general perspective, we have developed a minimal generic model where vesicles are represented by a 2D spring network and characterized by a minimum set of magnitudes: growth rate, permeability, bending stiffness, viscosity and temperature. We have performed hybrid molecuar dynamic simulations as a function of a reduced set of dimensionless parameters. Three main outcomes were observed: vesicles that grow without division, vesicles that divide symmetrically, and vesicles that act as generators of daughter vesicles. The type of outcome depends on the system parameters and specifically on its dynamics via two timescales. Furthermore, we found sets of parameters where the system shows size homeostasis. TRH was supported by Ramon Areces Foundation.

  9. Feruloyl Dioleoyglycerol Antioxidant Capacity in Phospholipid Vesicles

    USDA-ARS?s Scientific Manuscript database

    Ferulic acid and its esters are known to be effective antioxidants. Feruloyl dioleoylglycerol was assessed for its ability to serve as an antioxidant in model membrane phospholipid vesicles. The molecule was incorporated into single-lamellar vesicles of 1,2-dioleoyl-sn-glycero-3-phosphocholine at ...

  10. Amyloglucosidase enzymatic reactivity inside lipid vesicles

    PubMed Central

    Li, Mian; Hanford, Michael J; Kim, Jin-Woo; Peeples, Tonya L

    2007-01-01

    Efficient functioning of enzymes inside liposomes would open new avenues for applications in biocatalysis and bioanalytical tools. In this study, the entrapment of amyloglucosidase (AMG) (EC 3.2.1.3) from Aspergillus niger into dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles (MLVs) and large unilamellar vesicles (LUVs) was investigated. Negative-stain, freeze-fracture, and cryo-transmission electron microscopy images verified vesicle formation in the presence of AMG. Vesicles with entrapped AMG were isolated from the solution by centrifugation, and vesicle lamellarity was identified using fluorescence laser confocal microscopy. The kinetics of starch hydrolysis by AMG was modeled for two different systems, free enzyme in aqueous solution and entrapped enzyme within vesicles in aqueous suspension. For the free enzyme system, intrinsic kinetics were described by a Michaelis-Menten kinetic model with product inhibition. The kinetic constants, Vmax and Km, were determined by initial velocity measurements, and Ki was obtained by fitting the model to experimental data of glucose concentration-time curves. Predicted concentration-time curves using these kinetic constants were in good agreement with experimental measurements. In the case of the vesicles, the time-dependence of product (glucose) formation was experimentally determined and simulated by considering the kinetic behavior of the enzyme and the permeation of substrate into the vesicle. Experimental results demonstrated that entrapped enzymes were much more stable than free enyzme. The entrapped enzyme could be recycled with retention of 60% activity after 3 cycles. These methodologies can be useful in evaluating other liposomal catalysis operations. PMID:18271982

  11. Extracellular vesicles in coronary artery disease.

    PubMed

    Boulanger, Chantal M; Loyer, Xavier; Rautou, Pierre-Emmanuel; Amabile, Nicolas

    2017-02-02

    Membrane vesicles released in the extracellular space are composed of a lipid bilayer enclosing soluble cytosolic material and nuclear components. Extracellular vesicles include apoptotic bodies, exosomes, and microvesicles (also known previously as microparticles). Originating from different subcellular compartments, the role of extracellular vesicles as regulators of transfer of biological information, acting locally and remotely, is now acknowledged. Circulating vesicles released from platelets, erythrocytes, leukocytes, and endothelial cells contain potential valuable biological information for biomarker discovery in primary and secondary prevention of coronary artery disease. Extracellular vesicles also accumulate in human atherosclerotic plaques, where they affect major biological pathways, including inflammation, proliferation, thrombosis, calcification, and vasoactive responses. Extracellular vesicles also recapitulate the beneficial effect of stem cells to treat cardiac consequences of acute myocardial infarction, and now emerge as an attractive alternative to cell therapy, opening new avenues to vectorize biological information to target tissues. Although interest in microvesicles in the cardiovascular field emerged about 2 decades ago, that for extracellular vesicles, in particular exosomes, started to unfold a decade ago, opening new research and therapeutic avenues. This Review summarizes current knowledge on the role of extracellular vesicles in coronary artery disease, and their emerging potential as biomarkers and therapeutic agents.

  12. The effects of divided attention on auditory priming.

    PubMed

    Mulligan, Neil W; Duke, Marquinn; Cooper, Angela W

    2007-09-01

    Traditional theorizing stresses the importance of attentional state during encoding for later memory, based primarily on research with explicit memory. Recent research has begun to investigate the role of attention in implicit memory but has focused almost exclusively on priming in the visual modality. The present experiments examined the effect of divided attention on auditory implicit memory, using auditory perceptual identification, word-stem completion and word-fragment completion. Participants heard study words under full attention conditions or while simultaneously carrying out a distractor task (the divided attention condition). In Experiment 1, a distractor task with low response frequency failed to disrupt later auditory priming (but diminished explicit memory as assessed with auditory recognition). In Experiment 2, a distractor task with greater response frequency disrupted priming on all three of the auditory priming tasks as well as the explicit test. These results imply that although auditory priming is less reliant on attention than explicit memory, it is still greatly affected by at least some divided-attention manipulations. These results are consistent with research using visual priming tasks and have relevance for hypotheses regarding attention and auditory priming.

  13. An Extracellular Subtilase Switch for Immune Priming in Arabidopsis

    PubMed Central

    Mauch-Mani, Brigitte; Gil, Ma José; Vera, Pablo

    2013-01-01

    In higher eukaryotes, induced resistance associates with acquisition of a priming state of the cells for a more effective activation of innate immunity; however, the nature of the components for mounting this type of immunological memory is not well known. We identified an extracellular subtilase from Arabidopsis, SBT3.3, the overexpression of which enhances innate immune responses while the loss of function compromises them. SBT3.3 expression initiates a durable autoinduction mechanism that promotes chromatin remodeling and activates a salicylic acid(SA)-dependent mechanism of priming of defense genes for amplified response. Moreover, SBT3.3 expression-sensitized plants for enhanced expression of the OXI1 kinase gene and activation of MAP kinases following pathogen attack, providing additional clues for the regulation of immune priming by SBT3.3. Conversely, in sbt3.3 mutant plants pathogen-mediated induction of SA-related defense gene expression is drastically reduced and activation of MAP kinases inhibited. Moreover, chromatin remodeling of defense-related genes normally associated with activation of an immune priming response appear inhibited in sbt3.3 plants, further indicating the importance of the extracellular SBT3.3 subtilase in the establishment of immune priming. Our results also point to an epigenetic control in the regulation of plant immunity, since SBT3.3 is up-regulated and priming activated when epigenetic control is impeded. SBT3.3 represents a new regulator of primed immunity. PMID:23818851

  14. Visualization of SNARE-Mediated Hemifusion between Giant Unilamellar Vesicles Arrested by Myricetin

    PubMed Central

    Heo, Paul; Park, Joon-Bum; Shin, Yeon-Kyun; Kweon, Dae-Hyuk

    2017-01-01

    Neurotransmitters are released within a millisecond after Ca2+ arrives at an active zone. However, the vesicle fusion pathway underlying this synchronous release is yet to be understood. At the center of controversy is whether hemifusion, in which outer leaflets are merged while inner leaflets are still separated, is an on-pathway or off-pathway product of Ca2+-triggered exocytosis. Using the single vesicle fusion assay, we recently demonstrated that hemifusion is an on-pathway intermediate that immediately proceeds to full fusion upon Ca2+ triggering. It has been shown that the flavonoid myricetin arrests soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE)-mediated vesicle fusion at hemifusion, but that the hemifused vesicles spontaneously convert to full fusion when the myricetin clamp is removed by the enzyme laccase. In the present study, we visualized SNARE-mediated hemifusion between two SNARE-reconstituted giant unilamellar vesicles (GUVs) arrested by myricetin. The large size of the GUVs enabled us to directly image the hemifusion between them. When two merging GUVs were labeled with different fluorescent dyes, GUV pairs showed asymmetric fluorescence intensities depending on the position on the GUV pair consistent with what is expected for hemifusion. The flow of lipids from one vesicle to the other was revealed with fluorescence recovery after photobleaching (FRAP), indicating that the two membranes had hemifused. These results support the hypothesis that hemifusion may be the molecular status that primes Ca2+-triggered millisecond exocytosis. This study represents the first imaging of SNARE-driven hemifusion between GUVs. PMID:28408867

  15. Prime Contract Awards Alphabetically by Contractor, by State or Country, and Place, FY83, Part 1 (A & A Chemical Toilet Rentals-Benatec Associate).

    DTIC Science & Technology

    1983-01-01

    OftOBER - SEPfMBER FY 83_7 PAGE REPORT FORMA T L I NE I TEM 6 CONTRACTOR NAME ITEM 7 CITY NAME ITEM 7 STATE OR COUNTRY NAME ITEM 6 CONTRACTOR CODE ITEM 7...CITY CODE ITEM 7 STATE OR COUNTRY CODE L I ME 2 SUBMITTI NG DEPARTMENT REPORT MONTH ITEM 5 PURCHASING OFFICE ITEM IA REPORT NUMBER ITEM 2 CONTRACT...6 A 4 5 A 1026 3 B Y 2 A 164 2 C P9121 0129 NOOI83-82-DOO01 B C C 1 2 2 H999 000 51 MISCELLANEOUS TESTING AND IN 8 A 4 5 D 1026 2 A Y 2 B 92 2 C PB121

  16. Dollar Summary of Prime Contract Awards by State, Place, and Contractor, FY84, Part 1 (Adamsville, Alabama-Santa Clara, California).

    DTIC Science & Technology

    1984-01-01

    INC 167 167 C P I MACHINING CO INC 2,761 2,761 CALCOMP CORPORATION 55 55 CALIFORNIA CMPTR PRDTS INC 201 49 97 30 25 CARTWRIGHT ENGINEERING INC 6,000...UNITED MEDIA INC 28 28 UNITED STATES DEPARTMENT DEF 43 43 WALTER DORWIN TEAGUE INC 254 254 YEAGER MANUFACTURING CORF 36 36 TOTAL - ANAHEIM 1,020,504...POMONA T & T INDUSTRIES 57 57 WALTER DORWIN TEAGUE INC 2,013 2,013

  17. Transport vesicle formation in plant cells.

    PubMed

    Hwang, Inhwan; Robinson, David G

    2009-12-01

    In protein trafficking, transport vesicles bud from donor compartments and carry cargo proteins to target compartments with which they fuse. Thus, vesicle formation is an essential step in protein trafficking. As for mammals, plant cells contain the three major types of vesicles: COPI, COPII, and CCV and the major molecular players in vesicle-mediated protein transport are also present. However, plant cells generally contain more isoforms of the coat proteins, ARF GTPases and their regulatory proteins, as well as SNAREs. In addition, plants have established some unique subfamilies, which may reflect plant cell-specific conditions such as the absence of an ER-Golgi intermediate compartment and the combined activities of the TGN and early endosome. Thus, even though we are still at an early stage in understanding the physiological function of these proteins, it is already clear that vesicle-mediated protein transport in plant cells displays both similarities as well as differences in animal cells.

  18. Priming healthy eating. You can't prime all the people all of the time☆

    PubMed Central

    Forwood, Suzanna E.; Ahern, Amy L.; Hollands, Gareth J.; Ng, Yin-Lam; Marteau, Theresa M.

    2015-01-01

    Objective In the context of a food purchasing environment filled with advertising and promotions, and an increased desire from policy makers to guide individuals toward choosing healthier foods, this study tests whether priming methods that use healthy food adverts to increase preference for healthier food generalize to a representative population. MethodsIn two studies (Study 1 n = 143; Study 2 n = 764), participants were randomly allocated to a prime condition, where they viewed fruit and vegetable advertisements, or a control condition, with no advertisements. A subsequent forced choice task assessed preference between fruits and other sweet snacks. Additional measures included current hunger and thirst, dietary restraint, age, gender, education and self-reported weight and height. ResultsIn Study 1, hunger reduced preferences for fruits (OR (95% CI) = 0.38 (0.26–0.56), p < 0.0001), an effect countered by the prime (OR (95% CI) = 2.29 (1.33–3.96), p = 0.003). In Study 2, the effect of the prime did not generalize to a representative population. More educated participants, as used in Study 1, chose more fruit when hungry and primed (OR (95% CI) = 1.42 (1.13–1.79), p = 0.003), while less educated participants' fruit choice was unaffected by hunger or the prime. ConclusionThis study provides preliminary evidence that the effects of adverts on healthy eating choices depend on key individual traits (education level) and states (hunger), do not generalize to a broader population and have the potential to increase health inequalities arising from food choice. PMID:25636234

  19. Thermodynamics and kinetics of vesicles formation processes.

    PubMed

    Guida, Vincenzo

    2010-12-15

    Vesicles are hollow aggregates, composed of bilayers of amphiphilic molecules, dispersed into and filled with a liquid solvent. These aggregates can be formed either as equilibrium or as out of equilibrium meta-stable structures and they exhibit a rich variety of different morphologies. The surprising richness of structures, the vast range of industrial applications and the presence of vesicles in a number of biological systems have attracted the interest of numerous researchers and scientists. In this article, we review both the thermodynamics and the kinetics aspects of the phenomena of formation of vesicles. We start presenting the thermodynamics of bilayer membranes formation and deformation, with the aim of deriving the conditions for the existence of equilibrium vesicles. Specifically, we use the results from continuum thermodynamics to discuss the possibility of formation of stable equilibrium vesicles, from both mixed amphiphiles and single component systems. We also link the bilayer membrane properties to the molecular structure of the starting amphiphiles. In the second part of this article, we focus on the dynamics and kinetics of vesiculation. We review the process of vesicles formation both from planar lamellar phase under shear and from isotropic micelles. In order to clarify the physical mechanisms of vesicles formation, we continuously draw a parallel between emulsification and vesiculation processes. Specifically, we compare the experimental results, the driving forces and the relative scaling laws identified for the two processes. Describing the dynamics of vesicles formation, we also discuss why non equilibrium vesicles can be formed by kinetics control and why they are meta-stable. Understanding how to control the properties, the stability and the formation process of vesicles is of fundamental importance for a vast number of industrial applications.

  20. Question 7: New Aspects of Interactions Among Vesicles

    NASA Astrophysics Data System (ADS)

    Stano, Pasquale

    2007-10-01

    In this short article I discuss the relevance of two aspects of vesicle reactivity that are germane to understand the role of compartments in the origin of early cells. Studies of vesicle self-reproduction indicate that simple vesicles can grow and divide, maintaining inside most of their content and giving rise to a simple autopoietic system. New aspects of vesicle reactivity are also introduced, such as selection and competition processes within vesicle populations, emphasizing the concepts of vesicle diversity, inter-vesicles and vesicles environment interactions, intended as synthetic analogs of primitive ‘ecological’ processes.

  1. Complexin facilitates exocytosis and synchronizes vesicle release in two secretory model systems

    PubMed Central

    Lin, Ming-Yi; Rohan, Joyce G; Cai, Haijiang; Reim, Kerstin; Ko, Chien-Ping; Chow, Robert H

    2013-01-01

    Complexins (Cplxs) are small, SNARE-associated proteins believed to regulate fast, calcium-triggered exocytosis. However, studies have pointed to either an inhibitory and/or facilitatory role in exocytosis, and the role of Cplxs in synchronizing exocytosis is relatively unexplored. Here, we compare the function of two types of complexin, Cplx 1 and 2, in two model systems of calcium-dependent exocytosis. In mouse neuromuscular junctions (NMJs), we find that lack of Cplx 1 significantly reduces and desynchronizes calcium-triggered synaptic transmission; furthermore, high-frequency stimulation elicits synaptic facilitation, instead of normal synaptic depression, and the degree of facilitation is highly sensitive to the amount of cytoplasmic calcium buffering. In Cplx 2-null adrenal chromaffin cells, we also find decreased and desynchronized evoked release, and identify a significant reduction in the vesicle pool close to the calcium channels (immediately releasable pool, IRP). Viral transduction with either Cplx 1 or 2 rescues both the size of the evoked response and the synchronicity of release, and it restores the IRP size. Our findings in two model systems are mutually compatible and indicate a role of Cplx 1 and 2 in facilitating vesicle priming, and also lead to the new hypothesis that Cplxs may synchronize vesicle release by promoting coupling between secretory vesicles and calcium channels. PMID:23401610

  2. Priming against environmental challenges and proteomics in plants: Update and agricultural perspectives

    PubMed Central

    Tanou, Georgia; Fotopoulos, Vasileios; Molassiotis, Athanassios

    2012-01-01

    Priming is the cellular state in which the harmful effects of abiotic stress factors in plants are hindered by pre-exposure to a stimulus, thus resulting in greater survival. It is becoming increasingly evident that priming techniques (e.g., external application of natural or synthetic compounds in plants) can enhance the tolerance of crops to environmental stresses. Innovative systems biology approaches such as proteomics are currently recognized as essential tools to understand the molecular mechanisms underlying plant responses to environmental stimuli and priming phenomena. The few published proteomic studies on priming in the context of environmental stress identify key protein targets and signaling pathways which are being involved in the alleviation of negative effects of stress factors. Since priming is a very promising strategy in modern crop production management, further research is needed in order to establish the global picture of priming phenomena against environmental challenges as well as to characterize specific priming-related protein indicators in plants. PMID:22973291

  3. All Prime Contract Awards by State or Country, Place, and Contractor, FY 87. Part 8. Abbott Laboratories, Illinois-West Des Moines, Iowa.

    DTIC Science & Technology

    1987-01-01

    C14 41 C 404N 00 I ~ N ( N 1 N.. .4 N4 C14 41 04 C4 N4 .4 i 0-IL (4 .- li CO2 I) C4 N N N J " 4 C4 -4i (4 r . 4 C4 0I (N i -I ( WOOL 00 0 00 - 00-4 I...ME~tS BY STATE Olt COSEIRY PLACE ANS 44 COTRACTO FY U7.. (U) WMINTON EMMITERS SERVICES (DOD) DC DIRECTORATE FOR I.. L? DIOR/STII-87/PT-87LNLRSIFIE F

  4. Analysis of Yeast Extracellular Vesicles.

    PubMed

    Rodrigues, Marcio L; Oliveira, Debora L; Vargas, Gabriele; Girard-Dias, Wendell; Franzen, Anderson J; Frasés, Susana; Miranda, Kildare; Nimrichter, Leonardo

    2016-01-01

    Extracellular vesicles (EV) are important carriers of biologically active components in a number of organisms, including fungal cells. Experimental characterization of fungal EVs suggested that these membranous compartments are likely involved in the regulation of several biological events. In fungal pathogens, these events include mechanisms of disease progression and/or control, suggesting potential targets for therapeutic intervention or disease prophylaxis. In this manuscript we describe methods that have been used in the last 10 years for the characterization of EVs produced by yeast forms of several fungal species. Experimental approaches detailed in this chapter include ultracentrifugation methods for EV fractionation, chromatographic approaches for analysis of EV lipids, microscopy techniques for analysis of both intracellular and extracellular vesicular compartments, interaction of EVs with host cells, and physical chemical analysis of EVs by dynamic light scattering.

  5. Development and characterization of nanopore system for nano-vesicle analysis

    NASA Astrophysics Data System (ADS)

    Goyal, Gaurav

    Nano-vesicles have recently attracted a lot of attention in research and medical communities and are very promising next-generation drug delivery vehicles. This is due to their biocompatibility, biodegradability and their ability to protect drug cargo and deliver it to site-specific locations, while maintaining the desired pharmacokinetic profile. The interaction of these drug loaded vesicles with the recipient cells via adsorption, endocytosis or receptor mediated internalization involve significant bending and deformation and is governed by mechanical properties of the nano-vesicles. Currently, the mechanical characteristics of nano-vesicles are left unexplored because of the difficulties associated with vesicle analysis at sub-100 nm length scale. The need for a complete understanding of nano-vesicle interaction with each other and the recipient cells warrants development of an analytical tool capable of mechanical investigation of individual vesicles at sub-100 nm scale. This dissertation presents investigation of nano-vesicle deformability using resistive pulse sensing and solid-state nanopore devices. The dissertation is divided into four chapters. Chapter 1 discusses the motivation, specific aims and presents an overview of nanoparticle characterization techniques, resistive pulse sensing background and principles, techniques for fabricating solid-state nanopores, as well the deformation behavior of giant vesicles when placed in electric field. Chapter 2 is dedicated to understanding of the scientific principles governing transport of sub-100 nm particles in dilute solutions. We investigated the translocation of rigid nanoparticles through nanopores at salt concentrations < 50 mM. When using low electrolyte strength, surface effects become predominant and resulted in unconventional current signatures in our experiments. It prompted us to explore the effects of different experimental parameters using Multiphysics simulations, in order to optimize our system

  6. Time-dependent quantum wave packet study of the Ar+H{sub 2}{sup +}{yields}ArH{sup +}+H reaction on a new ab initio potential energy surface for the ground electronic state (1{sup 2}A Prime )

    SciTech Connect

    Hu Mei; Liu Xinguo; Tan Ruishan; Li Hongzheng; Xu Wenwu

    2013-05-07

    A new global potential energy surface for the ground electronic state (1{sup 2}A Prime ) of the Ar+H{sub 2}{sup +}{yields}ArH{sup +}+H reaction has been constructed by multi-reference configuration interaction method with Davidson correction and a basis set of aug-cc-pVQZ. Using 6080 ab initio single-point energies of all the regions for the dynamics, a many-body expansion function form has been used to fit these points. The quantum reactive scattering dynamics calculations taking into account the Coriolis coupling (CC) were carried out on the new potential energy surface over a range of collision energies (0.03-1.0 eV). The reaction probabilities and integral cross sections for the title reaction were calculated. The significance of including the CC quantum scattering calculation has been revealed by the comparison between the CC and the centrifugal sudden approximation calculation. The calculated cross section is in agreement with the experimental result at collision energy 1.0 eV.

  7. Oxygen transfer rate identifies priming compounds in parsley cells.

    PubMed

    Schilling, Jana Viola; Schillheim, Britta; Mahr, Stefan; Reufer, Yannik; Sanjoyo, Sandi; Conrath, Uwe; Büchs, Jochen

    2015-11-25

    In modern agriculture, the call for an alternative crop protection strategy increases because of the desired reduction of fungicide and pesticide use and the continuously evolving resistance of pathogens and pests to agrochemicals. The direct activation of the plant immune system does not provide a promising plant protection measure because of high fitness costs. However, upon treatment with certain natural or synthetic compounds, plant cells can promote to a fitness cost-saving, primed state of enhanced defense. In the primed state, plants respond to biotic and abiotic stress with faster and stronger activation of defense, and this is often associated with immunity and abiotic stress tolerance. Until now, the identification of chemical compounds with priming-inducing activity (so-called plant activators) relied on tedious and invasive approaches, or required the late detection of secreted furanocoumarin phytoalexins in parsley cell cultures. Thus, simple, fast, straightforward, and noninvasive techniques for identifying priming-inducing compounds for plant protection are very welcome. This report demonstrates that a respiration activity-monitoring system (RAMOS) can identify compounds with defense priming-inducing activity in parsley cell suspension in culture. RAMOS relies on the quasi-continuous, noninvasive online determination of the oxygen transfer rate (OTR). Treatment of parsley culture cells with the known plant activator salicylic acid (SA), a natural plant defense signal, resulted in an OTR increase. Addition of the defense elicitor Pep13, a cell wall peptide of Phythophthora sojae, induced two distinctive OTR peaks that were higher in SA-primed cells than in unprimed cells upon Pep13 challenge. Both, the OTR increase after priming with SA and the Pep13 challenge were dose-dependent. Furthermore, there was a close correlation of a compound's activity to enhance the oxygen consumption in parsley cells and its capacity to prime Pep13-induced furanocoumarin

  8. Dollar Summary of Prime Contract Awards by State, County, Contractor, and Place, Fiscal Year 1987. Part 3. Alger, Michigan-Washita, Oklahoma.

    DTIC Science & Technology

    1987-01-01

    Cawficaton) Dollar sunrary of Prinne Contract Awards by State, County, Contractor, and Place, FY 87. Part 3 ( Alger , Michigan-Washita, Oklahoma) 12. PERSONAL...Z6.0c 4z c= --s -’ o4 2 ~ ~ ~ z C tL "CC.))wz uw 04)=m XI CC 0 *a a ) CC C 44 444) 1 0C MsggC Ox -A z OC OC.CU - C - - - - - 04 4 o o C-ww4).E<<< 4...40 44 N 1c m Jc 4wt . .. J - I SI4 4 x I-L -- - N 0 Io.c c Imw w I- I 1> I >1 01 004 m~ tl C)U) U) 001 ) N 00 5z. U 00 xw 3 N 4 01 .4N C) N 44 :1 00 OW

  9. Polymeric Microgels as Potential Drug Delivery Vesicles

    NASA Astrophysics Data System (ADS)

    McDonough, Ryan; Streletzky, Kiril; Bayachou, Mekki; Peiris, Pubudu

    2010-03-01

    The temperature dependent volume phase change of cross-linked amphiphilic molecules (microgels) suggests their use as drug delivery vesicles. Drug particles aggregate in the slightly hydrophobic microgel interior. They are stored in equilibrium until the critical temperature (Tv) is reached where the volume phase change limits available space, thus expelling the drugs. This loading property of hydroxypropylcellulose (HPC) microgels was tested using amperometric analytical techniques. Small molecules inside microgels do not approach the electrode surface, which decreases current signal. A room temperature (Troom) flow amperometric measurement comparing microgel/paracetamol solution with control paracetamol samples yielded about 20 percent concentration reduction in the microgel sample. Results from the steady-state electrochemical experiment confirm the 20 percent concentration drop in the microgel sample compared to the control sample at Troom. Using the steady-state experiment with a cyclic temperature ramp from Troom to beyond Tv showed that the paracetamol concentration change between the temperature extremes was greater for the microgels than for the controls. An evolving aspect of the study is the characterization of microgel shrinkage from in situ, temperature controlled liquid AFM images as compared to previously completed DLS characterization of the same microgel sample.

  10. Space Place Prime

    NASA Technical Reports Server (NTRS)

    Fitzpatrick, Austin J.; Novati, Alexander; Fisher, Diane K.; Leon, Nancy J.; Netting, Ruth

    2013-01-01

    Space Place Prime is public engagement and education software for use on iPad. It targets a multi-generational audience with news, images, videos, and educational articles from the Space Place Web site and other NASA sources. New content is downloaded daily (or whenever the user accesses the app) via the wireless connection. In addition to the Space Place Web site, several NASA RSS feeds are tapped to provide new content. Content is retained for the previous several days, or some number of editions of each feed. All content is controlled on the server side, so features about the latest news, or changes to any content, can be made without updating the app in the Apple Store. It gathers many popular NASA features into one app. The interface is a boundless, slidable- in-any-direction grid of images, unique for each feature, and iconized as image, video, or article. A tap opens the feature. An alternate list mode presents menus of images, videos, and articles separately. Favorites can be tagged for permanent archive. Face - book, Twitter, and e-mail connections make any feature shareable.

  11. Prime Diagnosticity in Short-Term Repetition Priming: Is Primed Evidence Discounted, Even when It Reliably Indicates the Correct Answer?

    ERIC Educational Resources Information Center

    Weidemann, Christoph T.; Huber, David E.; Shiffrin, Richard M.

    2008-01-01

    The authors conducted 4 repetition priming experiments that manipulated prime duration and prime diagnosticity in a visual forced-choice perceptual identification task. The strength and direction of prime diagnosticity produced marked effects on identification accuracy, but those effects were resistant to subsequent changes of diagnosticity.…

  12. Characterization of Alternaria infectoria extracellular vesicles

    PubMed Central

    Silva, Branca M.A.; Prados-Rosales, Rafael; Espadas-Moreno, Javier; Wolf, Julie M.; Luque-Garcia, Jose L.; Gonçalves, Teresa; Casadevall, Arturo

    2015-01-01

    Many fungi use membrane vesicles to transport complex molecules across their cell walls. Like mammalian exosomes, fungal vesicles contain lipids, proteins, and polysaccharides, many of which are associated with virulence. Here we identify and characterize extracellular vesicles (EVs) in Alternaria infectoria, a ubiquitous, environmental filamentous fungus that is also an opportunistic human pathogen. Examination of the A. infectoria EVs revealed a morphology similar to that of vesicles described in other fungal species. Of note, proteomic analysis detected a reduced number of vesicle-associated proteins. There were two prevalent categories among the 20 identified proteins, including the polysaccharide metabolism group, probably related to plant host invasion or biosynthesis/degradation of cell wall components, and the nuclear proteins, especially DNA repair enzymes. We also found enzymes related to pigment synthesis, adhesion to the host cell, and trafficking of vesicles/organelles/molecules. This is the first time EV secretions have been identified in a filamentous fungus. We believe that these vesicles might have a role in virulence. PMID:24576997

  13. Signaling for Vesicle Mobilization and Synaptic Plasticity

    PubMed Central

    Levitan, Edwin S.

    2008-01-01

    The hypothesis that release of classical neurotransmitters and neuropeptides is facilitated by increasing the mobility of small synaptic vesicles (SSVs) and dense core vesicles (DCVs) could not be tested until the advent of methods for visualizing these secretory vesicles in living nerve terminals. In fact, fluorescence imaging studies have only since 2005 established that activity increases secretory vesicle mobility in motoneuron terminals and chromaffin cells. Mobilization of DCVs and SSVs appears to be due to liberation of hindered vesicles to promote quicker diffusion. However, F-actin and synapsin, which have been featured in mobilization models, are not required for activity-dependent increases in the mobility of DCVs or SSVs. Most recently, the signaling required for sustained mobilization has been identified for Drosophila motoneuron DCVs and shown to increase synaptic transmission. Specifically, presynaptic endoplasmic reticulum ryanodine receptor (RyR)-mediated Ca2+ release activates Ca2+/calmodulin-dependent kinase II (CamKII) to mobilize DCVs and induce post-tetanic potentiation (PTP) of neuropeptide release in the Drosophila neuromuscular junction. The shared signaling for increasing vesicle mobility and PTP links vesicle mobilization and synaptic plasticity. PMID:18446451

  14. Optical Manipulation of Vesicles for Optofluidic Applications

    SciTech Connect

    Vasdekis, Andreas E.; Scott, E. A.; O'Neil, C. P.; Psaltis, D.; Hubbell, J. A.

    2013-09-12

    In this report, we review our recent results in the optical micromanipulation of vesicles. Traditionally, vesicle manipulation has been possible by employing photon momentum and optical trapping, giving rise to unique observations of vesicle shape changes and soft matter mechanics. Contrary to these attempts, we employ photon energy rather than momentum, by sensitizing vesicles with an oxidizing moiety. The later converts incident photons to reactive oxygen species, which in turn attack and compromise the stability of the vesicle membrane. Both coherent and incoherent radiation was employed. Polymersome re-organization into smaller diameter vesicles was possible by focusing the excitation beam in the vicinity of the polymersomes. Extended vesicle illumination with a collimated beam lead to their complete destabilization and micelle formation. Single particle analysis revealed that payload release takes place within seconds of illumination in an explosive burst. We will discuss the destabilization and payload release kinetics, as revealed by high resolution microscopy at the single particle level, as well as potential applications in single cell biomodulation.

  15. Golgi cisternal unstacking stimulates COPI vesicle budding and protein transport.

    PubMed

    Wang, Yanzhuang; Wei, Jen-Hsuan; Bisel, Blaine; Tang, Danming; Seemann, Joachim

    2008-02-20

    The Golgi apparatus in mammalian cells is composed of flattened cisternae that are densely packed to form stacks. We have used the Golgi stacking protein GRASP65 as a tool to modify the stacking state of Golgi cisternae. We established an assay to measure protein transport to the cell surface in post-mitotic cells in which the Golgi was unstacked. Cells with an unstacked Golgi showed a higher transport rate compared to cells with stacked Golgi membranes. Vesicle budding from unstacked cisternae in vitro was significantly increased compared to stacked membranes. These results suggest that Golgi cisternal stacking can directly regulate vesicle formation and thus the rate of protein transport through the Golgi. The results further suggest that at the onset of mitosis, unstacking of cisternae allows extensive and rapid vesiculation of the Golgi in preparation for its subsequent partitioning.

  16. Golgi Cisternal Unstacking Stimulates COPI Vesicle Budding and Protein Transport

    PubMed Central

    Wang, Yanzhuang; Wei, Jen-Hsuan; Bisel, Blaine; Tang, Danming; Seemann, Joachim

    2008-01-01

    The Golgi apparatus in mammalian cells is composed of flattened cisternae that are densely packed to form stacks. We have used the Golgi stacking protein GRASP65 as a tool to modify the stacking state of Golgi cisternae. We established an assay to measure protein transport to the cell surface in post-mitotic cells in which the Golgi was unstacked. Cells with an unstacked Golgi showed a higher transport rate compared to cells with stacked Golgi membranes. Vesicle budding from unstacked cisternae in vitro was significantly increased compared to stacked membranes. These results suggest that Golgi cisternal stacking can directly regulate vesicle formation and thus the rate of protein transport through the Golgi. The results further suggest that at the onset of mitosis, unstacking of cisternae allows extensive and rapid vesiculation of the Golgi in preparation for its subsequent partitioning. PMID:18297130

  17. Direct Measurement of Pore Dynamics and Leakage Induced by a Model Antimicrobial Peptide in Single Vesicles and Cells.

    PubMed

    Burton, Matthew G; Huang, Qi M; Hossain, Mohammed A; Wade, John D; Palombo, Enzo A; Gee, Michelle L; Clayton, Andrew H A

    2016-06-28

    Antimicrobial peptides are promising therapeutic alternatives to counter growing antimicrobial resistance. Their precise mechanism of action remains elusive, however, particularly with respect to live bacterial cells. We investigated the interaction of a fluorescent melittin analogue with single giant unilamellar vesicles, giant multilamellar vesicles, and bilamellar Gram-negative Escherichia coli (E. coli) bacteria. Time-lapse fluorescence lifetime imaging microscopy was employed to determine the population distribution of the fluorescent melittin analogue between pore state and membrane surface state, and simultaneously measure the leakage of entrapped fluorescent species from the vesicle (or bacterium) interior. In giant unilamellar vesicles, leakage from vesicle interior was correlated with an increase in level of pore states, consistent with a stable pore formation mechanism. In giant multilamellar vesicles, vesicle leakage occurred more gradually and did not appear to correlate with increased pore states. Instead pore levels remained at a low steady-state level, which is more in line with coupled equilibria. Finally, in single bacterial cells, significant increases in pore levels were observed over time, which were correlated with only partial loss of cytosolic contents. These observations suggested that pore formation, as opposed to complete dissolution of membrane, was responsible for the leakage of contents in these systems, and that the bacterial membrane has an adaptive capacity that resists peptide attack. We interpret the three distinct pore dynamics regimes in the context of the increasing physical and biological complexity of the membranes.

  18. Extracellular vesicles: Exosomes, microvesicles, and friends

    PubMed Central

    Stoorvogel, Willem

    2013-01-01

    Cells release into the extracellular environment diverse types of membrane vesicles of endosomal and plasma membrane origin called exosomes and microvesicles, respectively. These extracellular vesicles (EVs) represent an important mode of intercellular communication by serving as vehicles for transfer between cells of membrane and cytosolic proteins, lipids, and RNA. Deficiencies in our knowledge of the molecular mechanisms for EV formation and lack of methods to interfere with the packaging of cargo or with vesicle release, however, still hamper identification of their physiological relevance in vivo. In this review, we focus on the characterization of EVs and on currently proposed mechanisms for their formation, targeting, and function. PMID:23420871

  19. Vesicle membrane fluctuations at nm resolution

    NASA Astrophysics Data System (ADS)

    Chen, Kejia; Bae, Sung Chul; Min, Chang-Ki; Granick, Steve; Granick Group Team

    2011-03-01

    We measure membrane thermal fluctuations with nanometer spatial resolution and microsecond time resolution, extending a scattering technique used at the Curie Institute to study red blood cell dynamics (Timo Betz et al., Proc. Nat. Acad. Sci. USA 106, 15320, 2009). A laser beam is focused at the leading edge of a phospholipid vesicle membrane and the forward scattered light is detected by a quadrant photodiode. The measurements over 4 orders of magnitude of frequency allow quantification of more complete fluctuation spectra than competing methods, and therefore fuller understanding of the vesicle membrane mechanics. As a proof of concept, we quantify how adsorbed nanoparticles stiffen giant unilamellar vesicles (GUVs).

  20. Rupture of lipid vesicles near solid surfaces

    NASA Astrophysics Data System (ADS)

    Takáts-Nyeste, Annamária; Derényi, Imre

    2014-11-01

    The behavior of lipid vesicles near solid surfaces, despite its scientific and technological significance, is poorly understood. By simultaneously taking into account (i) the dynamics of spontaneous pore opening and closing in surface bound vesicles; (ii) their volume loss via leakage through the pores; (iii) and the propagation of their contact line, we have developed a simple model that can fully describe the detailed mechanism of and provide the necessary conditions for the rupture of vesicles and the subsequent formation of supported lipid bilayers. The predictions of the model are in qualitative agreement with many of the experimental observations.

  1. The PRIME Lab biomedical program

    NASA Astrophysics Data System (ADS)

    Jackson, George S.; Elmore, David; Rickey, Frank A.; Musameh, Sharif M.; Sharma, Pankaj; Hillegonds, Darren; Coury, Louis; Kissinger, Peter

    2000-10-01

    The biomedical accelerator mass spectrometry (AMS) initiative at PRIME Lab including the status of equipment and sample preparation is described. Several biomedical projects are underway involving one or more of the nuclides: 14C, 26Al and 41Ca. Routine production of CaF 2 and graphite is taking place. Finally, the future direction and plans for improvement of the biomedical program at PRIME Lab are discussed.

  2. MIL-PRIME Program System

    NASA Astrophysics Data System (ADS)

    Rall, F. T., Jr.

    1982-11-01

    The MIL-PRIME Program was developed to provide the Aeronautical Systems Division with a specifications and standards program for the development of new weapon systems. This program was started in 1976 and is still in the process of being implemented. This presentation provides the background and insight into the MIL PRIME System, the use of these new documents in the acquisition process, and the current status of the program.

  3. Affective priming of perceived environmental restorativeness.

    PubMed

    Stevens, Paul

    2014-02-01

    Research into the perceived restorativeness of environments tends to focus on the Kaplans' Attention Restoration Theory at the expense of the affective considerations of Ulrich's psychoevolutionary model. To better understand the role of emotion, this study used contextual text-based primers (newspaper articles) to manipulate participants' affective state (positive or negative) prior to them rating different environments using the Restorative Components Scale. Sixty-nine participants completed the web-based study, being pseudo-randomly allocated to the positive- or negative-prime condition before rating three natural and three urban environments. Natural environments were rated as more restorative than urban, with negative-priming giving higher mean ratings for all environments. This effect was overall statistically significant for two components (Being Away and Fascination), but only Fascination showed a significant interaction of affective-prime and environment, a larger effect being seen for natural environments. Results are discussed in terms of current understanding of the interrelationship between attentional and affective processes. © 2013 International Union of Psychological Science.

  4. Immune priming in arthropods: an update focusing on the red flour beetle.

    PubMed

    Milutinović, Barbara; Peuß, Robert; Ferro, Kevin; Kurtz, Joachim

    2016-08-01

    Immune priming has now been demonstrated in a wide range of invertebrate species. Studies testing this phenomenon largely differ in terms of experimental design, host-parasite combinations, agents used for priming, and in particular the degree of demonstrated specificity of the primed response. This review provides an overview of known and putative mechanisms underlying broad-spectrum and specific immune priming in arthropods. We focus on insects and particularly the red flour beetle Tribolium castaneum, where priming has been demonstrated within and across generations. We will also draw attention to the relevance of routes of priming and infection, which can occur septically and orally, with largely differing physiology. For oral priming, an involvement of gut microbiota was demonstrated in mosquitoes and flour beetles. Generally, a primed state could result from long-lasting immune activation or a form of memory that does not entail lingering immune components. Moreover, the primed state could also be of a qualitatively different kind than the challenge response. Finally, we will consider that there should be natural variation in priming capability, and therefore a possibility to study this trait with experimental evolution approaches.

  5. Test Sequence Priming in Recognition Memory

    ERIC Educational Resources Information Center

    Johns, Elizabeth E.; Mewhort, D. J. K.

    2009-01-01

    The authors examined priming within the test sequence in 3 recognition memory experiments. A probe primed its successor whenever both probes shared a feature with the same studied item ("interjacent priming"), indicating that the study item like the probe is central to the decision. Interjacent priming occurred even when the 2 probes did…

  6. Test Sequence Priming in Recognition Memory

    ERIC Educational Resources Information Center

    Johns, Elizabeth E.; Mewhort, D. J. K.

    2009-01-01

    The authors examined priming within the test sequence in 3 recognition memory experiments. A probe primed its successor whenever both probes shared a feature with the same studied item ("interjacent priming"), indicating that the study item like the probe is central to the decision. Interjacent priming occurred even when the 2 probes did…

  7. Repeated Priming Increases Memory Accessibility in Infants

    ERIC Educational Resources Information Center

    Bearce, Karen Hildreth; Rovee-Collier, Carolyn

    2006-01-01

    In previous research on priming (reactivation) with 3-month-olds, two primes recovered a forgotten memory faster than one, suggesting that prior priming had increased the accessibility of the forgotten memory. Exploiting the fact that the minimum duration of a prime indexes the accessibility of the forgotten memory, we currently examined whether…

  8. The PrimeTime Expose: Reactions and Recommendations.

    ERIC Educational Resources Information Center

    Child Care Information Exchange, 1991

    1991-01-01

    Describes "Day Care Nightmares," a two-part expose on ABC's PrimeTime Live, broadcast in June 1991, in which negative claims were made about the state of day care in the United States. A variety of advocates, policymakers, and child care providers present their reactions to the shows and their recommendations on what action can be taken.…

  9. Psychotherapy Augmentation through Preconscious Priming

    PubMed Central

    Borgeat, François; O’Connor, Kieron; Amado, Danielle; St-Pierre-Delorme, Marie-Ève

    2013-01-01

    Objective: To test the hypothesis that repeated preconscious (masked) priming of personalized positive cognitions could augment cognitive change and facilitate achievement of patients’ goals following a therapy. Methods: Twenty social phobic patients (13 women) completed a 36-weeks study beginning by 12 weeks of group behavioral therapy. After the therapy, they received 6 weeks of preconscious priming and 6 weeks of a control procedure in a randomized cross-over design. The Priming condition involved listening twice daily with a passive attitude to a recording of individualized formulations of appropriate cognitions and attitudes masked by music. The Control condition involved listening to an indistinguishable recording where the formulations had been replaced by random numbers. Changes in social cognitions were measured by the Social Interaction Self Statements Test (SISST). Results: Patients improved following therapy. The Priming procedure was associated with increased positive cognitions and decreased negative cognitions on the SISST while the Control procedure was not. The Priming procedure induced more cognitive change when applied immediately after the group therapy. Conclusion: An effect of priming was observed on social phobia related cognitions in the expected direction. This self administered addition to a therapy could be seen as an augmentation strategy. PMID:23508724

  10. Locus of single-prime negative priming: the role of perceptual form.

    PubMed

    Chao, Hsuan-Fu

    2013-07-01

    Single-prime negative priming refers to the phenomenon in which after a single prime word is briefly presented, repeating it as the probe target results in a delay in responding to the target. The present study investigated the locus of this negative priming effect. Experiment 1 showed that repeating the identity of the prime produced a negative priming effect but merely repeating the response of the prime did not. Experiment 2 showed that the negative priming effect transformed into positive priming when the probe distractor was absent. Experiments 3 and 4 further revealed that single-prime negative priming was observed when the perceptual form was repeated. Taken together, these results suggest that single-prime negative priming involves a perceptual locus.

  11. Sequential Stereotype Priming: A Meta-Analysis.

    PubMed

    Kidder, Ciara K; White, Katherine R; Hinojos, Michelle R; Sandoval, Mayra; Crites, Stephen L

    2017-08-01

    Psychological interest in stereotype measurement has spanned nearly a century, with researchers adopting implicit measures in the 1980s to complement explicit measures. One of the most frequently used implicit measures of stereotypes is the sequential priming paradigm. The current meta-analysis examines stereotype priming, focusing specifically on this paradigm. To contribute to ongoing discussions regarding methodological rigor in social psychology, one primary goal was to identify methodological moderators of the stereotype priming effect-whether priming is due to a relation between the prime and target stimuli, the prime and target response, participant task, stereotype dimension, stimulus onset asynchrony (SOA), and stimuli type. Data from 39 studies yielded 87 individual effect sizes from 5,497 participants. Analyses revealed that stereotype priming is significantly moderated by the presence of prime-response relations, participant task, stereotype dimension, target stimulus type, SOA, and prime repetition. These results carry both practical and theoretical implications for future research on stereotype priming.

  12. The Intervenor Effect in Masked Priming: How Does Masked Priming Survive across an Intervening Word?

    ERIC Educational Resources Information Center

    Forster, Kenneth I.

    2009-01-01

    Four masked priming experiments are reported investigating the effect of inserting an unrelated word between the masked prime and the target. When the intervening word is visible, identity priming is reduced to the level of one-letter-different form priming, but form priming is largely unaffected. However, when the intervening word is itself…

  13. On the Control of Single-Prime Negative Priming: The Effects of Practice and Time Course

    ERIC Educational Resources Information Center

    Chao, Hsuan-Fu

    2009-01-01

    Single-prime negative priming refers to the phenomenon wherein repetition of a prime as the probe target results in delayed response. Sometimes this effect has been found to be contingent on participants' unawareness of the primes, and sometimes it has not. Further, sometimes this effect has been found to be eliminated when the prime could predict…

  14. The Intervenor Effect in Masked Priming: How Does Masked Priming Survive across an Intervening Word?

    ERIC Educational Resources Information Center

    Forster, Kenneth I.

    2009-01-01

    Four masked priming experiments are reported investigating the effect of inserting an unrelated word between the masked prime and the target. When the intervening word is visible, identity priming is reduced to the level of one-letter-different form priming, but form priming is largely unaffected. However, when the intervening word is itself…

  15. On the Control of Single-Prime Negative Priming: The Effects of Practice and Time Course

    ERIC Educational Resources Information Center

    Chao, Hsuan-Fu

    2009-01-01

    Single-prime negative priming refers to the phenomenon wherein repetition of a prime as the probe target results in delayed response. Sometimes this effect has been found to be contingent on participants' unawareness of the primes, and sometimes it has not. Further, sometimes this effect has been found to be eliminated when the prime could predict…

  16. Rupture of lipid vesicles by a broad-spectrum antiviral peptide: influence of vesicle size.

    PubMed

    Jackman, Joshua A; Zan, Goh Haw; Zhdanov, Vladimir P; Cho, Nam-Joon

    2013-12-19

    An amphipathic α-helical (AH) peptide was recently discovered that can rupture the lipid envelope of many viruses including HIV, hepatitis C, dengue, and herpes simplex. Despite its broad-spectrum activity, the AH peptide specifically targets small viruses only and does not affect large viruses. Indirect observations of virus size-specific targeting have been confirmed in a model system comprised of intact lipid vesicles on a gold substrate. Depending on vesicle size, AH peptide can promote vesicle rupture, but the mechanism by which vesicle size influences the rupture process remains to be elucidated. Herein, using the dynamic light scattering and quartz crystal microbalance with dissipation techniques, we have combined experiment and theory to understand the effects of vesicle size on the interaction between the AH peptide and vesicles. We identified that the AH peptide-binding interaction can induce a structural rearrangement of the vesicle's lipid bilayer, which occurs independently of vesicle size. Kinetic analysis also revealed that AH peptide-binding occurs cooperatively for small vesicles only. Binding cooperativity is consistent with pore formation leading to vesicle rupture. By contrast, for large vesicles, AH peptide-binding is noncooperative and does not cause vesicle rupture, suggesting that the binding interaction occurs via a different mechanism. Compared to previous estimates that AH peptide is most effective against viruses with a diameter of less than 70 nm, our evidence validates that AH peptide may target a wider size range of enveloped viruses up to 160 nm in diameter. Taken together, our findings provide a quantitative rationale to understand the targeting specificity of AH peptide as a broad-spectrum antiviral drug candidate.

  17. Repetition Priming and Cortical Arousal in Healthy Aging and Alzheimer’s Disease

    PubMed Central

    Kane, Amy E.; Festa, Elena K.; Salmon, David P.; Heindel, William C.

    2015-01-01

    Repetition priming refers to a form of implicit memory in which prior exposure to a stimulus facilitates the subsequent processing of the same or a related stimulus. One frequently used repetition priming task is word-stem completion priming. In this task, participants complete a series of beginning word stems with the first word that comes to mind after having viewed, in an unrelated context, words that can complete some of the stems. Patients with Alzheimer’s disease (AD) exhibit a significant deficit in word-stem completion priming, but the neural mechanisms underlying this deficit have yet to be identified. The present study examined the possibility that the word-stem completion priming deficit in AD is due to disruption of ascending neuromodulatory systems that mediate cortical arousal by comparing word-stem completion priming and behavioral measures of spatial orienting and phasic alerting. Results showed that in healthy elderly controls higher levels of phasic alerting were associated with a sharpening of the temporal dynamics of priming across two delay intervals: those with higher levels of alerting showed more immediate priming but less delayed priming than those with lesser levels of alerting. In patients with AD, priming was impaired despite intact levels of phasic alerting and spatial orienting, and group status rather than individual levels of alerting or orienting predicted the magnitude of their stem-completion priming. Furthermore, the change in priming across delays they displayed was not related to level of alerting or orienting. These findings support the role of the noradrenergic projection system in modulating the level of steady-state cortical activation (or “cortical tonus”) underlying both phasic alerting and the temporal dynamics of repetition priming. However, impaired priming in patients with AD does not appear to be due to disruption of this neuromodulatory system. PMID:25701794

  18. Repetition priming and cortical arousal in healthy aging and Alzheimer's disease.

    PubMed

    Kane, Amy E; Festa, Elena K; Salmon, David P; Heindel, William C

    2015-04-01

    Repetition priming refers to a form of implicit memory in which prior exposure to a stimulus facilitates the subsequent processing of the same or a related stimulus. One frequently used repetition priming task is word-stem completion priming. In this task, participants complete a series of beginning word stems with the first word that comes to mind after having viewed, in an unrelated context, words that can complete some of the stems. Patients with Alzheimer's disease (AD) exhibit a significant deficit in word-stem completion priming, but the neural mechanisms underlying this deficit have yet to be identified. The present study examined the possibility that the word-stem completion priming deficit in AD is due to disruption of ascending neuromodulatory systems that mediate cortical arousal by comparing word-stem completion priming and behavioral measures of spatial orienting and phasic alerting. Results showed that in healthy elderly controls higher levels of phasic alerting were associated with a sharpening of the temporal dynamics of priming across two delay intervals: those with higher levels of alerting showed more immediate priming but less delayed priming than those with lesser levels of alerting. In patients with AD, priming was impaired despite intact levels of phasic alerting and spatial orienting, and group status rather than individual levels of alerting or orienting predicted the magnitude of their stem-completion priming. Furthermore, the change in priming across delays they displayed was not related to level of alerting or orienting. These findings support the role of the noradrenergic projection system in modulating the level of steady-state cortical activation (or "cortical tonus") underlying both phasic alerting and the temporal dynamics of repetition priming. However, impaired priming in patients with AD does not appear to be due to disruption of this neuromodulatory system. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Tethering and pearling of vesicles in flow

    NASA Astrophysics Data System (ADS)

    Leonetti, Marc; Boedec, Gwenn; Jaeger, Marc; Irphe, Soft Matter Team; M2P2, Soft Matter Team

    2014-11-01

    Vesicles are studied by their own for their extensive use as biomedical vehicles for drug delivery but, they are also considered as red blood cell model. Indeed, vesicles are drops bounded by a phospholipidic membrane, an interface with peculiar mechanical properties. The membrane is a 2D incompressible fluid with a resistance to bending. The surface is preserved and there is no shear resistance as in capsules. The dynamics in flow depends mainly on their geometric ability to deform measured by the excess area or the reduced volume and on the hydrodynamical forcing such as settling and extensional flows for example characterized notably by the capillary number., we study the stability of thin phospholipidic tubes in flow. Notably, we show that pearls appear along stretched tethers, stretching which appears in vesicles during settling and in elongational flow for example. Numerical investigations of such vesicles under stress support the theoretical analysis.

  20. Kinetics of particle wrapping by a vesicle

    NASA Astrophysics Data System (ADS)

    Mirigian, Stephen; Muthukumar, Murugappan

    2013-07-01

    We present theoretical results on kinetics for the passive wrapping of a single, rigid particle by a flexible membrane. Using a simple geometric ansatz for the shape of the membrane/particle complex we first compute free energy profiles as a function of the particle size, attraction strength between the particle and vesicle, and material properties of the vesicle—bending stiffness and stretching modulus. The free energy profiles thus computed are taken as input to a stochastic model of the wrapping process, described by a Fokker-Planck equation. We compute average uptake rates of the particle into the vesicle. We find that the rate of particle uptake falls to zero outside of a thermodynamically allowed range of particle sizes. Within the thermodynamically allowed range of particle size, the rate of uptake is variable and we compute the optimal particle size and maximal uptake rate as a function of the attraction strength, the vesicle size, and vesicle material properties.

  1. Yeast membrane vesicles: isolation and general characteristics.

    PubMed

    Christensen, M S; Cirillo, V P

    1972-06-01

    Yeast membrane vesicles are formed when packed yeast are ground manually in a porcelain mortar and pestle with glass beads (0.2 mm diameter). These vesicles can be separated from the other components of the grinding mixture by a combination of centrifugation steps and elution from a column of the same glass beads (0.2 mm diameter). Isolated vesicles are osmotically sensitive, contain cytoplasmic components, and have energy-independent transport function. They are unable to metabolize glucose, but have respiratory function which is thought to be associated with intravesicular mitochondria. Invertase and oligomycin-insensitive adenosine triphosphatase are present in lysed vesicle preparations, and the appropriateness of these enzyme activities as membrane markers is discussed.

  2. Stability of Spherical Vesicles in Electric Fields

    PubMed Central

    2010-01-01

    The stability of spherical vesicles in alternating (ac) electric fields is studied theoretically for asymmetric conductivity conditions across their membranes. The vesicle deformation is obtained from a balance between the curvature elastic energies and the work done by the Maxwell stresses. The present theory describes and clarifies the mechanisms for the four types of morphological transitions observed experimentally on vesicles exposed to ac fields in the frequency range from 500 to 2 × 107 Hz. The displacement currents across the membranes redirect the electric fields toward the membrane normal to accumulate electric charges by the Maxwell−Wagner mechanism. These accumulated electric charges provide the underlying molecular mechanism for the morphological transitions of vesicles as observed on the micrometer scale. PMID:20575588

  3. Early dynamics of the semantic priming shift

    PubMed Central

    Lavigne, Frédéric; Chanquoy, Lucile; Dumercy, Laurent; Vitu, Françoise

    2013-01-01

    Semantic processing of sequences of words requires the cognitive system to keep several word meanings simultaneously activated in working memory with limited capacity. The real- time updating of the sequence of word meanings relies on dynamic changes in the associates to the words that are activated. Protocols involving two sequential primes report a semantic priming shift from larger priming of associates to the first prime to larger priming of associates to the second prime, in a range of long SOAs (stimulus-onset asynchronies) between the second prime and the target. However, the possibility for an early semantic priming shift is still to be tested, and its dynamics as a function of association strength remain unknown. Three multiple priming experiments are proposed that cross-manipulate association strength between each of two successive primes and a target, for different values of short SOAs and prime durations. Results show an early priming shift ranging from priming of associates to the first prime only to priming of strong associates to the first prime and all of the associates to the second prime. We investigated the neural basis of the early priming shift by using a network model of spike frequency adaptive cortical neurons (e.g., Deco & Rolls, 2005), able to code different association strengths between the primes and the target. The cortical network model provides a description of the early dynamics of the priming shift in terms of pro-active and retro-active interferences within populations of excitatory neurons regulated by fast and unselective inhibitory feedback. PMID:23717346

  4. Extracellular vesicles in parasitic diseases

    PubMed Central

    Marcilla, Antonio; Martin-Jaular, Lorena; Trelis, Maria; de Menezes-Neto, Armando; Osuna, Antonio; Bernal, Dolores; Fernandez-Becerra, Carmen; Almeida, Igor C.; del Portillo, Hernando A.

    2014-01-01

    Parasitic diseases affect billions of people and are considered a major public health issue. Close to 400 species are estimated to parasitize humans, of which around 90 are responsible for great clinical burden and mortality rates. Unfortunately, they are largely neglected as they are mainly endemic to poor regions. Of relevance to this review, there is accumulating evidence of the release of extracellular vesicles (EVs) in parasitic diseases, acting both in parasite–parasite inter-communication as well as in parasite–host interactions. EVs participate in the dissemination of the pathogen and play a role in the regulation of the host immune systems. Production of EVs from parasites or parasitized cells has been described for a number of parasitic infections. In this review, we provide the most relevant findings of the involvement of EVs in intercellular communication, modulation of immune responses, involvement in pathology, and their potential as new diagnostic tools and therapeutic agents in some of the major human parasitic pathogens. PMID:25536932

  5. Oxidative and other posttranslational modifications in extracellular vesicle biology.

    PubMed

    Szabó-Taylor, Katalin; Ryan, Brent; Osteikoetxea, Xabier; Szabó, Tamás G; Sódar, Barbara; Holub, Marcsilla; Németh, Andrea; Pálóczi, Krisztina; Pállinger, Éva; Winyard, Paul; Buzás, Edit I

    2015-04-01

    Extracellular vesicles including exosomes, microvesicles and apoptotic vesicles, are phospholipid bilayer surrounded structures secreted by cells universally, in an evolutionarily conserved fashion. Posttranslational modifications such as oxidation, citrullination, phosphorylation and glycosylation play diverse roles in extracellular vesicle biology. Posttranslational modifications orchestrate the biogenesis of extracellular vesicles. The signals extracellular vesicles transmit between cells also often function via modulating posttranslational modifications of target molecules, given that extracellular vesicles are carriers of several active enzymes catalysing posttranslational modifications. Posttranslational modifications of extracellular vesicles can also contribute to disease pathology by e.g. amplifying inflammation, generating neoepitopes or carrying neoepitopes themselves.

  6. Purification of coated vesicles by agarose gel electrophoresis

    PubMed Central

    1981-01-01

    We have applied agarose gel electrophoresis as a novel step in the purification of clathrin-coated vesicles. Preparations of coated vesicles obtained by sedimentation velocity and isopycnic centrifugation are resolved into two distinct fractions upon electrophoresis. The slower migrating fraction contains smooth vesicles, whereas the faster contains only coated vesicles and empty clathrin coats. The faster mobility of the coated vesicles is primarily caused by the acidic nature of clathrin. Coated vesicles from three different cell types have different mobilities. In each case, however, all of the major polypeptides previously attributed to coated vesicles comigrate with the now homogeneous particles, even though a powerful ATPase activity is completely removed. PMID:6265464

  7. Concentration-Independent Spontaneously Forming Biomimetric Vesicles

    NASA Astrophysics Data System (ADS)

    Nieh, M.-P.; Harroun, T. A.; Raghunathan, V. A.; Glinka, C. J.; Katsaras, J.

    2003-10-01

    In this Letter we present small-angle neutron scattering data from a biomimetic system composed of the phospholipids dimyristoyl and dihexanoyl phosphorylcholine (DMPC and DHPC, respectively). Doping DMPC-DHPC multilamellar vesicles with either the negatively charged lipid dimyristoyl phosphorylglycerol (DMPG, net charge -1) or the divalent cation, calcium (Ca2+), leads to the spontaneous formation of energetically stabilized monodisperse unilamellar vesicles whose radii are concentration independent and in contrast with previous experimental observations.

  8. Ceramidase Regulates Synaptic Vesicle Exocytosis and Trafficking

    PubMed Central

    Rohrbough, Jeffrey; Rushton, Emma; Palanker, Laura; Woodruff, Elvin; Matthies, Heinrich J. G.; Acharya, Usha; Acharya, Jairaj K.; Broadie, Kendal

    2009-01-01

    A screen for Drosophila synaptic dysfunction mutants identified slug-a-bed (slab). The slab gene encodes ceramidase, a central enzyme in sphingolipid metabolism and regulation. Sphingolipids are major constituents of lipid rafts, membrane domains with roles in vesicle trafficking, and signaling pathways. Null slab mutants arrest as fully developed embryos with severely reduced movement. The SLAB protein is widely expressed in different tissues but enriched in neurons at all stages of development. Targeted neuronal expression of slab rescues mutant lethality, demonstrating the essential neuronal function of the protein. C5-ceramide applied to living preparations is rapidly accumulated at neuromuscular junction (NMJ) synapses dependent on the SLAB expression level, indicating that synaptic sphingolipid trafficking and distribution is regulated by SLAB function. Evoked synaptic currents at slab mutant NMJs are reduced by 50–70%, whereas postsynaptic glutamate-gated currents are normal, demonstrating a specific presynaptic impairment. Hypertonic saline-evoked synaptic vesicle fusion is similarly impaired by 50–70%, demonstrating a loss of readily releasable vesicles. In addition, FM1-43 dye uptake is reduced in slab mutant presynaptic terminals, indicating a smaller cycling vesicle pool. Ultrastructural analyses of mutants reveal a normal vesicle distribution clustered and docked at active zones, but fewer vesicles in reserve regions, and a twofold to threefold increased incidence of vesicles linked together and tethered at the plasma membrane. These results indicate that SLAB ceramidase function controls presynaptic terminal sphingolipid composition to regulate vesicle fusion and trafficking, and thus the strength and reliability of synaptic transmission. PMID:15356190

  9. Structure formation of lipid membranes: Membrane self-assembly and vesicle opening-up to octopus-like micelles

    NASA Astrophysics Data System (ADS)

    Noguchi, Hiroshi

    2013-02-01

    We briefly review our recent studies on self-assembly and vesicle rupture of lipid membranes using coarse-grained molecular simulations. For single component membranes, lipid molecules self-assemble from random gas states to vesicles via disk-shaped clusters. Clusters aggregate into larger clusters, and subsequently the large disks close into vesicles. The size of vesicles are determined by kinetics than by thermodynamics. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle called bicelle can be formed. When both surfactants have negligibly low critical micelle concentration, it is found that bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and spontaneous curvature of the membrane monolayer.

  10. Elastic energy of polyhedral bilayer vesicles

    PubMed Central

    Haselwandter, Christoph A.; Phillips, Rob

    2011-01-01

    In recent experiments the spontaneous formation of hollow bilayer vesicles with polyhedral symmetry has been observed. On the basis of the experimental phenomenology it was suggested that the mechanism for the formation of bilayer polyhedra is minimization of elastic bending energy. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. In agreement with experiments, and provided that excess amphiphiles exhibiting spontaneous curvature are present in sufficient quantity, we find that polyhedral bilayer vesicles can indeed be energetically favorable compared to spherical bilayer vesicles. Consistent with experimental observations we also find that the bending energy associated with the vertices of bilayer polyhedra can be locally reduced through the formation of pores. However, the stabilization of polyhedral bilayer vesicles over spherical bilayer vesicles relies crucially on molecular segregation of excess amphiphiles along the ridges rather than the vertices of bilayer polyhedra. Furthermore, our analysis implies that, contrary to what has been suggested on the basis of experiments, the icosahedron does not minimize elastic bending energy among arbitrary polyhedral shapes and sizes. Instead, we find that, for large polyhedron sizes, the snub dodecahedron and the snub cube both have lower total bending energies than the icosahedron. PMID:21797397

  11. The Brownian dynamics of a lipid vesicle

    NASA Astrophysics Data System (ADS)

    Zhao, Hong; Shaqfeh, Eric

    2011-11-01

    We propose a Brownian dynamics simulation method to study the motion of a lipid vesicle in a suspending fluid. The lipid bilayer of the vesicle is modeled as a two-dimensional fluidic membrane with bending resistance and a high local area dilatational modulus. Using a Stokes flow boundary integral equation method, we calculate the grand mobility tensor of the deformable membrane at arbitrary viscosity ratio between the fluid inside and outside the vesicle. The fluctuation-dissipation theorem, as well as the drifting due to the configuration dependence of the diffusivity tensor, are rigorously accounted for. The flow transitions (tank-treading, tumbling and trembling) and the particle stresslet for an athermal vesicle in a simple shear flow calculated by the present method are in good agreement with existing results by a spectral boundary integral equation method. We demonstrate that the effect of Brownian motion is most significant for a tumbling vesicle. The thermal fluctuation tilts the vesicle off the shear plane, and the disruption of the originally two-dimensional tumbling orbit results in a qualitatively different three-dimensional ``wobbling'' motion. The change to the suspension rheology due to the altered dynamics is discussed.

  12. Metalization of lipid vesicles via electroless plating

    SciTech Connect

    Ferrar, W.T.; O'Brien, D.F.; Warshawsky, A.; Voycheck, C.L.

    1988-01-06

    The encapsulation of metallic particles and metallic oxides within lipid vesicles has recently been of interest for applications such as catalysis, water splitting, and magnetic control of spin coupling. In this communication the authors introduce the concept and practice of the deposition of metal on vesicles by using electroless plating techniques. Coordination of low valent transition metals to organic functional groups on the surface of the bilayer membrane provides a means of binding metal atoms to vesicles. Chemical reduction produced zero valent atoms which serve as sites for further metal deposition by the chemical reduction techniques of electroless plating. Specifically, this procedure involved the binding of a small amount of tetrachloropalladate to the vesicle bilayer, reduction of the palladium(II) to palladium(0), followed by the deposition of much larger amounts of metal from an electroless plating solution. Electroless plating solutions were used for the deposition of palladium, nickel, cobalt, or copper metal onto the catalytic palladium centers. Since the metallic particles were associated with the vesicles, colloids were formed that were stable in water for much longer periods than the control metal particles formed in water alone. If the vesicles were composed in part of unsaturated lipids, with the olefinic groups on the hydrocarbon chains, the initial evidence suggests the transition metal was directed into the bilayer, rather than staying on the surface.

  13. Differential detergent sensitivity of extracellular vesicle subpopulations.

    PubMed

    Osteikoetxea, Xabier; Sódar, Barbara; Németh, Andrea; Szabó-Taylor, Katalin; Pálóczi, Krisztina; Vukman, Krisztina V; Tamási, Viola; Balogh, Andrea; Kittel, Ágnes; Pállinger, Éva; Buzás, Edit Irén

    2015-10-14

    Extracellular vesicles (including exosomes, microvesicles and apoptotic bodies) are currently attracting rapidly increasing attention from various fields of biology due to their ability to carry complex information and act as autocrine, paracrine and even endocrine intercellular messengers. In the present study we investigated the sensitivity of size-based subpopulations of extracellular vesicles to different concentrations of detergents including sodium dodecyl sulphate, Triton X-100, Tween 20 and deoxycholate. We determined the required detergent concentration that lysed each of the vesicle subpopulations secreted by Jurkat, THP-1, MiaPaCa and U937 human cell lines. We characterized the vesicles by tunable resistive pulse sensing, flow cytometry and transmission electron microscopy. Microvesicles and apoptotic bodies were found to be more sensitive to detergent lysis than exosomes. Furthermore, we found evidence that sodium dodecyl sulphate and Triton X-100 were more effective in vesicle lysis at low concentrations than deoxycholate or Tween 20. Taken together, our data suggest that a combination of differential detergent lysis with tunable resistive pulse sensing or flow cytometry may prove useful for simple and fast differentiation between exosomes and other extracellular vesicle subpopulations as well as between vesicular and non-vesicular structures.

  14. Endothelial Extracellular Vesicles-Promises and Challenges.

    PubMed

    Hromada, Carina; Mühleder, Severin; Grillari, Johannes; Redl, Heinz; Holnthoner, Wolfgang

    2017-01-01

    Extracellular vesicles, including exosomes, microparticles, and apoptotic bodies, are phospholipid bilayer-enclosed vesicles that have once been considered as cell debris lacking biological functions. However, they have recently gained immense interest in the scientific community due to their role in intercellular communication, immunity, tissue regeneration as well as in the onset, and progression of various pathologic conditions. Extracellular vesicles of endothelial origin have been found to play a versatile role in the human body, since they are on the one hand known to contribute to cardiovascular diseases, but on the other hand have also been reported to promote endothelial cell survival. Hence, endothelial extracellular vesicles hold promising therapeutic potential to be used as a new tool to detect as well as treat a great number of diseases. This calls for clinically approved, standardized, and efficient isolation and characterization protocols to harvest and purify endothelial extracellular vesicles. However, such methods and techniques to fulfill stringent requirements for clinical trials have yet to be developed or are not harmonized internationally. In this review, recent advances and challenges in the field of endothelial extracellular vesicle research are discussed and current problems and limitations regarding isolation and characterization are pointed out.

  15. Elastic energy of polyhedral bilayer vesicles.

    PubMed

    Haselwandter, Christoph A; Phillips, Rob

    2011-06-01

    In recent experiments [M. Dubois, B. Demé, T. Gulik-Krzywicki, J.-C. Dedieu, C. Vautrin, S. Désert, E. Perez, and T. Zemb, Nature (London) 411, 672 (2001)] the spontaneous formation of hollow bilayer vesicles with polyhedral symmetry has been observed. On the basis of the experimental phenomenology it was suggested [M. Dubois, V. Lizunov, A. Meister, T. Gulik-Krzywicki, J. M. Verbavatz, E. Perez, J. Zimmerberg, and T. Zemb, Proc. Natl. Acad. Sci. USA 101, 15082 (2004)] that the mechanism for the formation of bilayer polyhedra is minimization of elastic bending energy. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. In agreement with experiments, and provided that excess amphiphiles exhibiting spontaneous curvature are present in sufficient quantity, we find that polyhedral bilayer vesicles can indeed be energetically favorable compared to spherical bilayer vesicles. Consistent with experimental observations we also find that the bending energy associated with the vertices of bilayer polyhedra can be locally reduced through the formation of pores. However, the stabilization of polyhedral bilayer vesicles over spherical bilayer vesicles relies crucially on molecular segregation of excess amphiphiles along the ridges rather than the vertices of bilayer polyhedra. Furthermore, our analysis implies that, contrary to what has been suggested on the basis of experiments, the icosahedron does not minimize elastic bending energy among arbitrary polyhedral shapes and sizes. Instead, we find that, for large polyhedron sizes, the snub dodecahedron and the snub cube both have lower total bending energies than the icosahedron.

  16. Horizontal Transmission of Cytosolic Sup35 Prions by Extracellular Vesicles

    PubMed Central

    Liu, Shu; Hossinger, André; Hofmann, Julia P.; Denner, Philip

    2016-01-01

    ABSTRACT Prions are infectious protein particles that replicate by templating their aggregated state onto soluble protein of the same type. Originally identified as the causative agent of transmissible spongiform encephalopathies, prions in yeast (Saccharomyces cerevisiae) are epigenetic elements of inheritance that induce phenotypic changes of their host cells. The prototype yeast prion is the translation termination factor Sup35. Prions composed of Sup35 or its modular prion domain NM are heritable and are transmitted vertically to progeny or horizontally during mating. Interestingly, in mammalian cells, protein aggregates derived from yeast Sup35 NM behave as true infectious entities that employ dissemination strategies similar to those of mammalian prions. While transmission is most efficient when cells are in direct contact, we demonstrate here that cytosolic Sup35 NM prions are also released into the extracellular space in association with nanometer-sized membrane vesicles. Importantly, extracellular vesicles are biologically active and are taken up by recipient cells, where they induce self-sustained Sup35 NM protein aggregation. Thus, in mammalian cells, extracellular vesicles can serve as dissemination vehicles for protein-based epigenetic information transfer. PMID:27406566

  17. Transfer of oleic acid between albumin and phospholipid vesicles

    SciTech Connect

    Hamilton, J.A.; Cistola, D.P.

    1986-01-01

    The net transfer of oleic acid between egg phosphatidylcholine unilamellar vesicles and bovine serum albumin has been monitored by TC NMR spectroscopy and 90% isotopically substituted (1- TC)oleic acid. The carboxyl chemical shifts of oleic acid bound to albumin were different from those for oleic acid in phospholipid vesicles. Therefore, in mixtures of donor particles, the equilibrium distribution of oleic acid was determined from chemical shift and peak intensity data without separation of donor and acceptor particles. In a system containing equal masses of albumin and phospholipid and a stoichiometry of 4-5 mol of oleic acid per mol of albumin, the oleic acid distribution was pH dependent, with greater than or equal to80% of the oleic acid associated with albumin at pH 7.4; association was greater than or equal to90% at pH 8.0. Decreasing the pH below 7.4 markedly decreased the proportion of fatty acid bound to albumin. The distribution was reversible with pH and was independent of whether vesicles or albumin acted as a donor. These data suggest that pH may strongly influence the partitioning of fatty acid between cellular membranes and albumin. The TC NMR method is also advantageous because it provides information about the structural environments of oleic acid bound to albumin or phospholipid, the ionization state of oleic acid in each environment, and the structural integrity of the vesicles. In addition, minimum and maximum limits for the exchange rates of oleic acid among different environments were obtained from the NMR data.

  18. Interleukin 12 acts directly on CD4+ T cells to enhance priming for interferon gamma production and diminishes interleukin 4 inhibition of such priming.

    PubMed Central

    Seder, R A; Gazzinelli, R; Sher, A; Paul, W E

    1993-01-01

    Naive CD4+ T cells produce interleukin 2 (IL-2) but little IL-4 or interferon gamma (IFN-gamma). In vitro, they develop into IL-4 or IFN-gamma producers depending on the conditions of the priming culture. Using T-cell receptor transgenic CD4+ T cells, the role of IL-12 and IL-4 in antigen-specific priming was examined. IL-12 substantially enhanced the ability of naive CD4+ T cells to develop into cells that produced IFN-gamma upon restimulation. However, it was not essential since anti-IL-12 antibodies failed to block the priming for IFN-gamma observed in the absence of exogenous IL-12. When both IL-12 and IL-4 were present in the priming culture, IL-12 did not inhibit priming for IL-4 production. In contrast, IL-4 diminished but did not abolish priming for IFN-gamma production. In an accessory cell-independent priming system, IL-12 strikingly augmented priming for IFN-gamma production, indicating that it acts directly on T cells. IFN-gamma itself did not enhance priming for IFN-gamma production in either accessory cell-dependent or independent systems. In an accessory cell-dependent system, the IL-12-mediated enhancement was not blocked by adding neutralizing anti-IFN-gamma monoclonal antibody. However, in an accessory cell-independent system, anti-IFN-gamma antibody did inhibit priming for IFN-gamma production leaving open a role for IFN-gamma in the priming process. These data indicate that IL-12 has a major effect on the inductive phase of T-cell priming by enhancing commitment to IFN-gamma production and thus can profoundly influence the state of immunity that develops. Images Fig. 4 PMID:7901851

  19. Extracellular Vesicles in Cardiovascular Disease: Potential Applications in Diagnosis, Prognosis, and Epidemiology.

    PubMed

    Jansen, Felix; Nickenig, Georg; Werner, Nikos

    2017-05-12

    Extracellular vesicles originate from diverse subcellular compartments and are released in the extracellular space. By transferring their cargoes into target cells and tissues, they now emerge as novel regulators of intercellular communication between adjacent and remote cells. Because vesicle composition and biological content are specific signatures of cellular activation and injury, their potential as diagnostic and prognostic biomarkers has raised significant interest in cardiovascular diseases. Characterization of circulating vesicles- or nonvesicles-bound nucleic acids represents a valuable tool for diagnosing and monitoring cardiovascular diseases, recently referred to as a liquid biopsy. Circulating extracellular vesicles offer a noninvasive and almost continuous access to circulating information on the disease state in epidemiological investigations. Finally, genetic engineering and cell-specific application of extracellular vesicles could display a novel therapeutic option for the treatment of cardiovascular diseases. In this review, we summarize the current knowledge about extracellular vesicles as diagnostic and prognostic biomarkers, as well as their potential applications for longitudinal epidemiological studies in cardiovascular diseases. © 2017 American Heart Association, Inc.

  20. Incorporation of Soft Particles into Lipid Vesicles: Effects of Particle Size and Elasticity.

    PubMed

    Yi, Xin; Gao, Huajian

    2016-12-13

    The interaction between particles and lipid biomembranes plays an essential role in many fields such as endocytosis, drug delivery, and intracellular traffic. Here we conduct a theoretical study on the incorporation of elastic particles of different sizes and rigidities into a lipid vesicle through adhesive wrapping. It is shown that while the incorporation of relatively small particles involves smooth shape evolution, the vesicle wrapping of large particles exhibits a discontinuous shape transition, followed by a protrusion of the vesicle membrane at infinitesimal cost of elastic deformation energy. Moreover, softer particles require stronger adhesion energy to achieve successful internalization and delay the onset of discontinuous shape transition to a higher wrapping degree. Depending on the adhesion energy, particle-vesicle size, and rigidity ratios, and the spontaneous curvature of the vesicle, a rich variety of wrapping phase diagrams consisting of stable and metastable states of no-wrapping, partial-wrapping, and full-wrapping are established. The underlying mechanism of the discontinuous shape transformation of the vesicle and the relation between the uptake proneness and uptake efficiency are discussed. These results shed further light on the elasticity effects in cellular uptake of elastic particles and may provide rational design guidelines for controlled endocytosis and diagnostics delivery.

  1. Transmembrane flux and receptor desensitization measured with membrane vesicles. Homogeneity of vesicles investigated by computer simulation.

    PubMed Central

    Cash, D J; Langer, R M; Subbarao, K; Bradbury, J R

    1988-01-01

    The use of membrane vesicles to make quantitative studies of transmembrane transport and exchange processes involves an assumption of homogeneity of the membrane vesicles. In studies of 86Rb+ exchange mediated by acetylcholine receptor from the electric organ of Electrophorus electricus and of 36Cl- exchange mediated by GABA receptor from rat brain, measurements of ion exchange and receptor desensitization precisely followed first order kinetics in support of this assumption. In other measurements a biphasic decay of receptor activity was seen. To elucidate the molecular properties of receptors from such measurements it is important to appreciate what the requirements of vesicle monodispersity are for meaningful results and what the effect of vesicle heterogeneity would be. The experiments were simulated with single vesicle populations with variable defined size distributions as well as with mixtures of different populations of vesicles. The properties of the receptors and their density in the membrane could be varied. Different receptors could be present on the same or different membrane vesicles. The simulated measurements were not very sensitive to size dispersity. A very broad size distribution of a single vesicle population was necessary to give rise to detectable deviations from first order kinetics or errors in the determined kinetic constants. Errors could become significant with mixtures of different vesicle populations, where the dispersity in initial ion exchange rate constant, proportional to the receptor concentration per internal volume, became large. In this case the apparent rate of receptor desensitization would diverge in opposite directions from the input value when measured by two different methods, suggesting an experimental test for such kinetic heterogeneity. A biphasic decrease of receptor activity could not be attributed to vesicle heterogeneity and must be due to desensitization processes with different rates. Significant errors would not

  2. Procoagulant and immunogenic properties of melanoma exosomes, microvesicles and apoptotic vesicles

    PubMed Central

    Muhsin-Sharafaldine, Morad-Rémy; Saunderson, Sarah C.; Dunn, Amy C.; Faed, James M.; Kleffmann, Torsten; McLellan, Alexander D.

    2016-01-01

    Extracellular vesicles (EV) are lipid particles released from eukaryotic cells into the extracellular fluid. Depending on the cell type or mechanism of release, vesicles vary in form and function and exert distinct functions in coagulation and immunity. Tumor cells may constitutively shed vesicles known as exosomes or microvesicles (MV). Alternatively, apoptosis induces the release of apoptotic blebs or vesicles (ApoV) from the plasma membrane. EV have been implicated in thrombotic events (the second highest cause of death in cancer patients) and tumor vesicles contribute to the anti-cancer immune response. In this study, we utilized the well characterized B16 melanoma model to determine the molecular composition and procoagulant and immunogenic potential of exosomes, MV and ApoV. Distinct patterns of surface and cytoplasmic molecules (tetraspanins, integrins, heat shock proteins and histones) were expressed between the vesicle types. Moreover, in vitro coagulation assays revealed that membrane-derived vesicles, namely MV and ApoV, were more procoagulant than exosomes–with tissue factor and phosphatidylserine critical for procoagulant activity. Mice immunized with antigen-pulsed ApoV and challenged with B16 tumors were protected out to 60 days, while lower protection rates were afforded by MV and exosomes. Together the results demonstrate distinct phenotypic and functional differences between vesicle types, with important procoagulant and immunogenic functions emerging for membrane-derived MV and ApoV versus endosome-derived exosomes. This study highlights the potential of EV to contribute to the prothrombotic state, as well as to anti-cancer immunity. PMID:27462921

  3. Procoagulant and immunogenic properties of melanoma exosomes, microvesicles and apoptotic vesicles.

    PubMed

    Muhsin-Sharafaldine, Morad-Rémy; Saunderson, Sarah C; Dunn, Amy C; Faed, James M; Kleffmann, Torsten; McLellan, Alexander D

    2016-08-30

    Extracellular vesicles (EV) are lipid particles released from eukaryotic cells into the extracellular fluid. Depending on the cell type or mechanism of release, vesicles vary in form and function and exert distinct functions in coagulation and immunity. Tumor cells may constitutively shed vesicles known as exosomes or microvesicles (MV). Alternatively, apoptosis induces the release of apoptotic blebs or vesicles (ApoV) from the plasma membrane. EV have been implicated in thrombotic events (the second highest cause of death in cancer patients) and tumor vesicles contribute to the anti-cancer immune response. In this study, we utilized the well characterized B16 melanoma model to determine the molecular composition and procoagulant and immunogenic potential of exosomes, MV and ApoV. Distinct patterns of surface and cytoplasmic molecules (tetraspanins, integrins, heat shock proteins and histones) were expressed between the vesicle types. Moreover, in vitro coagulation assays revealed that membrane-derived vesicles, namely MV and ApoV, were more procoagulant than exosomes-with tissue factor and phosphatidylserine critical for procoagulant activity. Mice immunized with antigen-pulsed ApoV and challenged with B16 tumors were protected out to 60 days, while lower protection rates were afforded by MV and exosomes. Together the results demonstrate distinct phenotypic and functional differences between vesicle types, with important procoagulant and immunogenic functions emerging for membrane-derived MV and ApoV versus endosome-derived exosomes. This study highlights the potential of EV to contribute to the prothrombotic state, as well as to anti-cancer immunity.

  4. Involvement of vH+-ATPase in synaptic vesicle swelling

    PubMed Central

    Shin, Leah; Basi, Nirukti; Jeremic, Aleksandar; Lee, Jin-Sook; Cho, Won Jin; Chen, ZhiHui; Abu-Hamdah, Rania; Oupicky, David; Jena, Bhanu P

    2010-01-01

    Secretory vesicle swelling is central to cell secretion, however the underlying mechanism of vesicle swelling, particularly synaptic vesicles, is not completely understood. The Gαi3-PLA2-mediated involvement of water channel AQP-1 in the regulation of secretory vesicle swelling in exocrine pancreas, and the Gαo-mediated AQP-6 involvement in synaptic vesicle swelling in neurons, has previously been reported. Furthermore, the role of vH+-ATPase in neurotransmitter transport into synaptic vesicles, has also been shown. Using nanometer scale precision measurements of isolated synaptic vesicles, the present study reports for the first time, the involvement of vH+-ATPase in GTP-Gαo-mediated synaptic vesicle swelling. Results from this study, demonstrate that the GTP-Gαo-mediated vesicle swelling is vH+-ATPase–dependent, and pH sensitive. Zeta potential measurements of isolated synaptic vesicles further demonstrate, a bafilomycin-sensitive vesicle acidification, following the GTP-Gαo-induced swelling stimulus. Since water channels are bidirectional, and the vH+-ATPase inhibitor bafilomycin decreases both the volume of isolated synaptic vesicles and GTP-mastoparan stimulated swelling, suggests vH+-ATPase to be upstream of AQP-6, in the pathway leading from Gαo-stimulated swelling of synaptic vesicles. Vesicle acidification is therefore a prerequisite for AQP-6 mediated gating of water into synaptic vesicles. PMID:19610106

  5. Extracellular Vesicles in Metabolic Syndrome.

    PubMed

    Martínez, M Carmen; Andriantsitohaina, Ramaroson

    2017-05-12

    Metabolic syndrome defines a cluster of interrelated risk factors for cardiovascular disease and diabetes mellitus. These factors include metabolic abnormalities, such as hyperglycemia, elevated triglyceride levels, low high-density lipoprotein cholesterol levels, high blood pressure, and obesity, mainly central adiposity. In this context, extracellular vesicles (EVs) may represent novel effectors that might help to elucidate disease-specific pathways in metabolic disease. Indeed, EVs (a terminology that encompasses microparticles, exosomes, and apoptotic bodies) are emerging as a novel mean of cell-to-cell communication in physiology and pathology because they represent a new way to convey fundamental information between cells. These microstructures contain proteins, lipids, and genetic information able to modify the phenotype and function of the target cells. EVs carry specific markers of the cell of origin that make possible monitoring their fluctuations in the circulation as potential biomarkers inasmuch their circulating levels are increased in metabolic syndrome patients. Because of the mixed components of EVs, the content or the number of EVs derived from distinct cells of origin, the mode of cell stimulation, and the ensuing mechanisms for their production, it is difficult to attribute specific functions as drivers or biomarkers of diseases. This review reports recent data of EVs from different origins, including endothelial, smooth muscle cells, macrophages, hepatocytes, adipocytes, skeletal muscle, and finally, those from microbiota as bioeffectors of message, leading to metabolic syndrome. Depicting the complexity of the mechanisms involved in their functions reinforce the hypothesis that EVs are valid biomarkers, and they represent targets that can be harnessed for innovative therapeutic approaches. © 2017 American Heart Association, Inc.

  6. Priming and Habituation for Faces: Individual Differences and Inversion Effects

    ERIC Educational Resources Information Center

    Rieth, Cory A.; Huber, David E.

    2010-01-01

    Immediate repetition priming for faces was examined across a range of prime durations in a threshold identification task. Similar to word repetition priming results, short duration face primes produced positive priming whereas long duration face primes eliminated or reversed this effect. A habituation model of such priming effects predicted that…

  7. Priming and Habituation for Faces: Individual Differences and Inversion Effects

    ERIC Educational Resources Information Center

    Rieth, Cory A.; Huber, David E.

    2010-01-01

    Immediate repetition priming for faces was examined across a range of prime durations in a threshold identification task. Similar to word repetition priming results, short duration face primes produced positive priming whereas long duration face primes eliminated or reversed this effect. A habituation model of such priming effects predicted that…

  8. Carburetor priming system for internal combustion engines

    SciTech Connect

    Everts, R.G.

    1986-05-20

    A carburetor priming system is described for an internal combustion engine, the engine including: a fuel tank, a carburetor having an air inlet, a fuel-air mixing throat, and an air-fuel mixture outlet communicating with the combustion chambers of the engine, the priming system comprising, in combination: (a) a hollow housing having air inlet openings in the walls thereof, shaped and dimensioned to cover the air inlet of the carburetor; (b) an air-permeable wick retained in the housing; (c) priming fuel pump means, including (i) a depressable hollow resilient priming bulb, (ii) a priming fuel supply conduit extending between the fuel tank and the interior of the priming bulb, (iii) a priming fuel discharge conduit extending between the interior of the priming bulb and the wick, (iv) a normally closed first check valve in the priming fuel supply conduit which opens to permit fuel to flow into the priming bulb and which closes when the priming bulb is depressed, (v) a normally closed second check valve disposed in the priming fuel discharge conduit, the second check valve being mechanically actuated by external pressure on the priming bulb, to open when the priming bulb is depressed.

  9. Oligomerizations of deoxyadenosine bis-phosphates and of their 3-prime-5-prime, 3-prime-3-prime, and 5-prime-5-prime dimers - Effects of a pyrophosphate-linked, poly(T) analog

    NASA Technical Reports Server (NTRS)

    Visscher, J.; Bakker, C. G.; Schwartz, Alan W.

    1990-01-01

    The effect of a 3-prime-5-prime pyrophosphate-linked oligomer of pTp on oligomerizations of pdAp and of its 3-prime-5-prime, 3-prime-3-prime, and 5-prime-5-prime dimers was investigated, using HPLC to separate the reaction mixtures; peak detection was by absorbance monitoring at 254 nm. It was expected that the dimers would form stable complexes with the template, with the degree of stability depending upon the internal linkage of each dimer. It was found that, although the isomers differ substantially in their oligomerization behavior in the absence of template, the analog-template catalyzes the oligomerization to about the same extent in all three cases.

  10. Oligomerizations of deoxyadenosine bis-phosphates and of their 3-prime-5-prime, 3-prime-3-prime, and 5-prime-5-prime dimers - Effects of a pyrophosphate-linked, poly(T) analog

    NASA Technical Reports Server (NTRS)

    Visscher, J.; Bakker, C. G.; Schwartz, Alan W.

    1990-01-01

    The effect of a 3-prime-5-prime pyrophosphate-linked oligomer of pTp on oligomerizations of pdAp and of its 3-prime-5-prime, 3-prime-3-prime, and 5-prime-5-prime dimers was investigated, using HPLC to separate the reaction mixtures; peak detection was by absorbance monitoring at 254 nm. It was expected that the dimers would form stable complexes with the template, with the degree of stability depending upon the internal linkage of each dimer. It was found that, although the isomers differ substantially in their oligomerization behavior in the absence of template, the analog-template catalyzes the oligomerization to about the same extent in all three cases.

  11. Priming in Systemic Plant Immunity

    SciTech Connect

    Jung, Ho Won; Tschaplinski, Timothy J; Wang, Lin; Glazebrook, Jane; Greenberg, Jean T.

    2009-01-01

    Upon local infection, plants possess inducible systemic defense responses against their natural enemies. Bacterial infection results in the accumulation to high levels of the mobile metabolite C9-dicarboxylic acid azelaic acid in the vascular sap of Arabidopsis. Azelaic acid confers local and systemic resistance against Pseudomonas syringae. The compound primes plants to strongly accumulate salicylic acid (SA), a known defense signal, upon infection. Mutation of a gene induced by azelaic acid (AZI1) results in the specific loss in plants of systemic immunity triggered by pathogen or azelaic acid and of the priming of SA induction. AZI1, a predicted secreted protein, is also important for generating vascular sap that confers disease resistance. Thus, azelaic acid and AZI1 comprise novel components of plant systemic immunity involved in priming defenses.

  12. Structural Priming: A Critical Review

    PubMed Central

    Pickering, Martin J.; Ferreira, Victor S.

    2009-01-01

    Repetition is a central phenomenon of behavior, and researchers make extensive use of it to illuminate psychological functioning. In the language sciences, a ubiquitous form of such repetition is structural priming, a tendency to repeat or better process a current sentence because of its structural similarity to a previously experienced (“prime”) sentence (Bock, 1986). The recent explosion of research in structural priming has made it the dominant means of investigating the processes involved in the production (and increasingly, comprehension) of complex expressions such as sentences. This review considers its implications for the representation of syntax and the mechanisms of production, comprehension, and their relationship. It then addresses the potential functions of structural priming, before turning to its implications for first language acquisition, bilingualism, and aphasia We close with theoretical and empirical recommendations for future investigations. PMID:18444704

  13. Coarse-grained simulation of lipid vesicles with ``n-atic'' orientational order

    NASA Astrophysics Data System (ADS)

    Geng, Jun; Selinger, Jonathan; Selinger, Robin

    2012-02-01

    We perform coarse-grained simulation studies of fluid lipid vesicles with in-plane ``n-atic'' orientational order associated with the shape of lipid head group, to test the theoretical predictions of Park, Lubensky and MacKintosh [1] for resulting vesicle shape and defect structures. Our simulation model uses a single layer coarse-grained implicit-solvent approach proposed by Yuan et al [2], with addition of an extra vector degree of freedom representing in-plane orientational order. We carry out simulation studies for n=1 to 6, examining in each case the spatial distribution of defects and resulting deformation of the vesicle. An initially spherical vesicle (genus zero) with n-atic order has a ground state with 2n vortices of strength 1/n, as expected, but the observed equilibrium shapes are sometimes quite different from those predicted theoretically. For the n=1 case, we find that the vesicle may become trapped in a disordered, long-lived metastable state with extra +/- defects whose pair-annihilation is inhibited by local changes in membrane curvature, and thus may never reach its predicted ground state. [4pt] [1] J. Park, T. C. Lubensky, and F. C. MacKintosh, Europhys. Lett. 20, 279 (1992)[0pt] [2] H. Yuan, C. Huang, Ju Li, G. Lykotrafitis, and S. Zhang, Phys. Rev. E 82, 011905 (2010)

  14. Granule Exocytosis Contributes to Priming and Activation of the Human Neutrophil Respiratory Burst

    PubMed Central

    Uriarte, Silvia M.; Rane, Madhavi J.; Luerman, Gregory C.; Barati, Michelle T.; Ward, Richard A.; Nauseef, William M.; McLeish, Kenneth R.

    2013-01-01

    The role of exocytosis in the human neutrophil respiratory burst was determined using a fusion protein (TAT–SNAP-23) containing the HIV transactivator of transcription (TAT) cell-penetrating sequence and the N-terminal SNARE domain of synaptosome-associated protein-23 (SNAP-23). This agent inhibited stimulated exocytosis of secretory vesicles and gelatinase and specific granules but not azurophil granules. GST pulldown showed that TAT–SNAP-23 bound to the combination of vesicle-associated membrane protein-2 and syntaxin-4 but not to either individually. TAT–SNAP-23 reduced phagocytosis-stimulated hydrogen peroxide production by 60% without affecting phagocytosis or generation of HOCl within phagosomes. TAT–SNAP-23 had no effect on fMLF-stimulated superoxide release but significantly inhibited priming of this response by TNF-α and platelet-activating factor. Pretreatment with TAT–SNAP-23 inhibited the increase in plasma membrane expression of gp91phox in TNF-α–primed neutrophils, whereas TNF-α activation of ERK1/2 and p38 MAPK was not affected. The data demonstrate that neutrophil granule exocytosis contributes to phagocytosis-induced respiratory burst activity and plays a critical role in priming of the respiratory burst by increasing expression of membrane components of the NADPH oxidase. PMID:21642540

  15. On the control of single-prime negative priming: the effects of practice and time course.

    PubMed

    Chao, Hsuan-Fu

    2009-09-01

    Single-prime negative priming refers to the phenomenon wherein repetition of a prime as the probe target results in delayed response. Sometimes this effect has been found to be contingent on participants' unawareness of the primes, and sometimes it has not. Further, sometimes this effect has been found to be eliminated when the prime could predict the following probe target, and sometimes it has not. An integrative account is postulated to account for these findings. Three experiments supported this account by demonstrating that (a) regardless of the proportion of prime repetition, negative priming was the default effect; (b) the control mechanism was triggered to activate the prime after there was enough practice for the detection of the contingency between the prime and probe; and (c) it took time for the control mechanism to overcome the negative-priming effect and produce a positive-priming effect.

  16. Tube extrusion from permeabilized giant vesicles

    NASA Astrophysics Data System (ADS)

    Borghi, N.; Kremer, S.; Askovic, V.; Brochard-Wyart, F.

    2006-08-01

    This letter reports the permeabilization effects of chemical additives on mechanical properties of Giant Unilamellar Vesicles (GUVs). We use a surfactant, Tween 20, inducing transient pores and a protein, Streptolysin O, inducing permanent pores in the membrane. Lipid tubes are extracted from GUVs anchored onto the tip of a micro-needle and submitted to hydrodynamic flows. On bare vesicles, tube extrusion is governed by the entropic elasticity of the membrane. The vesicle tension increases until it balances the flow velocity U and the tube reaches a stationary length. In permeabilized vesicles, the membrane tension is maintained at a constant value σp by the permeation of inner solution through nanometric pores. This allows extrusion of "infinite" tubes at constant velocity that never reach a stationary length. Tween-20 preliminary results suggest that σp strongly depends on surfactant concentration. For Streptolysin O, we have measured σp vs. U and found two regimes: a "high-porosity" regime for U > Up0 and a "low-porosity" regime for U < Up0, where Up0 is related to the number of pores on the vesicle surface.

  17. Mechanics of post-fusion exocytotic vesicle

    NASA Astrophysics Data System (ADS)

    Stephens, Thomas; Wu, Zhanghan; Liu, Jian

    2017-06-01

    Exocytosis is an important cellular process controlled by metabolic signaling. It involves vesicle fusion to the plasma membrane, followed by the opening of a fusion pore, and the subsequent release of the vesicular lumen content into the extracellular space. While most modeling efforts focus on the events leading to membrane fusion, how the vesicular membrane remodels after fusing to plasma membrane remains unclear. This latter event dictates the nature and the efficiency of exocytotic vesicular secretions, and is thus critical for exocytotic function. We provide a generic membrane mechanical model to systematically study the fate of post-fusion vesicles. We show that while membrane stiffness favors full-collapse vesicle fusion into the plasma membrane, the intravesicular pressure swells the vesicle and causes the fusion pore to shrink. Dimensions of the vesicle and its associated fusion pore further modulate this mechanical antagonism. We systematically define the mechanical conditions that account for the full spectrum of the observed vesicular secretion modes. Our model therefore can serve as a unified theoretical framework that sheds light on the elaborate control mechanism of exocytosis.

  18. Haloarchaea and the Formation of Gas Vesicles

    PubMed Central

    Pfeifer, Felicitas

    2015-01-01

    Halophilic Archaea (Haloarchaea) thrive in salterns containing sodium chloride concentrations up to saturation. Many Haloarchaea possess genes encoding gas vesicles, but only a few species, such as Halobacterium salinarum and Haloferax mediterranei, produce these gas-filled, proteinaceous nanocompartments. Gas vesicles increase the buoyancy of cells and enable them to migrate vertically in the water body to regions with optimal conditions. Their synthesis depends on environmental factors, such as light, oxygen supply, temperature and salt concentration. Fourteen gas vesicle protein (gvp) genes are involved in their formation, and regulation of gvp gene expression occurs at the level of transcription, including the two regulatory proteins, GvpD and GvpE, but also at the level of translation. The gas vesicle wall is solely formed of proteins with the two major components, GvpA and GvpC, and seven additional accessory proteins are also involved. Except for GvpI and GvpH, all of these are required to form the gas permeable wall. The applications of gas vesicles include their use as an antigen presenter for viral or pathogen proteins, but also as a stable ultrasonic reporter for biomedical purposes. PMID:25648404

  19. Synaptic vesicle recycling: steps and principles

    PubMed Central

    Rizzoli, Silvio O

    2014-01-01

    Synaptic vesicle recycling is one of the best-studied cellular pathways. Many of the proteins involved are known, and their interactions are becoming increasingly clear. However, as for many other pathways, it is still difficult to understand synaptic vesicle recycling as a whole. While it is generally possible to point out how synaptic reactions take place, it is not always easy to understand what triggers or controls them. Also, it is often difficult to understand how the availability of the reaction partners is controlled: how the reaction partners manage to find each other in the right place, at the right time. I present here an overview of synaptic vesicle recycling, discussing the mechanisms that trigger different reactions, and those that ensure the availability of reaction partners. A central argument is that synaptic vesicles bind soluble cofactor proteins, with low affinity, and thus control their availability in the synapse, forming a buffer for cofactor proteins. The availability of cofactor proteins, in turn, regulates the different synaptic reactions. Similar mechanisms, in which one of the reaction partners buffers another, may apply to many other processes, from the biogenesis to the degradation of the synaptic vesicle. PMID:24596248

  20. Activation of calcineurin by phosphotidylserine containing vesicles

    SciTech Connect

    Politino, M.; King, M.M.

    1986-05-01

    Calcineurin (CaN) is a Ca/sup 2 +/- and calmodulin-regulated phosphatase. Recent findings suggested an association of CaN with biological membranes and prompted the present investigation into the interactions of the phosphatase with phospholipids in vitro. In the absence of calmodulin, sonicated preparations of phosphatidylserine (PS) provided a five-fold activation of the Ni- and Mn-supported activities of CaN towards (/sup 32/P) histone Hl; activation in the presence of calmodulin was much less pronounced. Half-maximal activation in the absence of calmodulin required approximately 0.1 mg/ml of PS. Activation of CaN was also observed with mixed vesicles of phosphatidylcholine (PC) containing 20% PS but not with PC alone, or with phosphatidylethanolamine (PE). Molecular sieve chromatography on Ultrogel AcA 34 provided further evidence that CaN associates with phospholipid vesicles composed of PS, or PC containing 20% PS, but not with vesicles of PC or PE. Complete association with medium sized vesicles of PS and PC/PS required Ca/sup 2 +/ ions; in the absence of the metal ion at least 60% of the enzyme failed to interact with the lipids while the remainder preferentially migrated with larger vesicles. These results suggest a role for Ca/sup 2 +/ in regulating CaN's interaction with phospholipids.

  1. Lysozyme binding onto cat-anionic vesicles.

    PubMed

    Bonincontro, A; Spigone, E; Ruiz Peña, M; Letizia, C; La Mesa, C

    2006-12-15

    Mixing aqueous sodium dodecylsulfate with cetyltrimethylammonium bromide solutions in mole ratios close to (1.7/1.0) allows the formation of cat-anionic vesicles with an excess of negative charges on the outer surface. The vesicular dispersions are mixed with lysozyme, and interact electrostatically with the positive charges on the protein, forming lipo-plexes. Dielectric relaxation, zeta-potential, and light scattering indicate the occurrence of interactions between vesicles and the protein. According to CD, the vesicle-adsorbed protein retains its native conformation. Binding and surface saturation, inferred by dielectric relaxation and zeta-potential, fulfil a charge neutralisation stoichiometry. Adsorbed lysozyme promotes the vesicle clustering and is concomitant with the lipo-plexes flocculation. Above the charge neutralisation threshold, lysozyme in excess remains dispersed in molecular form. Attempts were made to determine in what conditions protein release from the vesicles occurs. Accordingly, the full neutralisation of sodium dodecylsulfate in excess by cetyltrimethylammonium bromide ensures the lipo-plexes break-up, the precipitation of the mixed surfactants and the protein release in native form.

  2. Getting to know the extracellular vesicle glycome.

    PubMed

    Gerlach, Jared Q; Griffin, Matthew D

    2016-04-01

    Extracellular vesicles (EVs) are a diverse population of complex biological particles with diameters ranging from approximately 20 to 1000 nm. Tremendous interest in EVs has been generated following a number of recent, high-profile reports describing their potential utility in diagnostic, prognostic, drug delivery, and therapeutic roles. Subpopulations, such as exosomes, are now known to directly participate in cell-cell communication and direct material transfer. Glycomics, the 'omic' portion of the glycobiology field, has only begun to catalog the surface oligosaccharide and polysaccharide structures and also the carbohydrate-binding proteins found on and inside EVs. The EV glycome undoubtedly contains vital clues essential to better understanding the function, biogenesis, release and transfer of vesicles, however getting at this information is technically challenging and made even more so because of the small physical size of the vesicles and the typically minute yield from physiological-scale biological samples. Vesicle micro-heterogeneity which may be related to specific vesicle origins and functions presents a further challenge. A number of primary studies carried out over the past decade have turned up specific and valuable clues regarding the composition and roles of glycan structures and also glycan binding proteins involved EV biogenesis and transfer. This review explores some of the major EV glycobiological research carried out to date and discusses the potential implications of these findings across the life sciences.

  3. Time-resolved SERS for characterizing extracellular vesicles

    NASA Astrophysics Data System (ADS)

    Rojalin, Tatu; Saari, Heikki; Somersalo, Petter; Laitinen, Saara; Turunen, Mikko; Viitala, Tapani; Wachsmann-Hogiu, Sebastian; Smith, Zachary J.; Yliperttula, Marjo

    2017-02-01

    The aim of this work is to develop a platform for characterizing extracellular vesicles (EV) by using gold-polymer nanopillar SERS arrays simultaneously circumventing the photoluminescence-related disadvantages of Raman with a time-resolved approach. EVs are rich of biochemical information reporting of, for example, diseased state of the biological system. Currently, straightforward, label-free and fast EV characterization methods with low sample consumption are warranted. In this study, SERS spectra of red blood cell and platelet derived EVs were successfully measured and their biochemical contents analyzed using multivariate data analysis techniques. The developed platform could be conveniently used for EV analytics in general.

  4. Symmetry breaking of vesicle shapes in Poiseuille flow.

    PubMed

    Farutin, Alexander; Misbah, Chaouqi

    2011-07-01

    Vesicle behavior under unbounded axial Poiseuille flow is studied analytically. Our study reveals subtle features of the dynamics. It is established that there exists a stable off-centerline steady-state solution for low enough flow strength. This solution appears as a symmetry-breaking bifurcation upon lowering the flow strength and includes slipper shapes, which are characteristic of red blood cells in the microvasculature. A stable axisymmetric solution exists for any flow strength provided the excess area is small enough. It is shown that the mechanism of the symmetry breaking depends on the geometry of the flow: The bifurcation is subcritical in axial Poiseuille flow and supercritical in planar flow.

  5. Two synaptobrevin molecules are sufficient for vesicle fusion in central nervous system synapses.

    PubMed

    Sinha, Raunak; Ahmed, Saheeb; Jahn, Reinhard; Klingauf, Jurgen

    2011-08-23

    Exocytosis of synaptic vesicles (SVs) during fast synaptic transmission is mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly formed by the coil-coiling of three members of this protein family: vesicle SNARE protein, synaptobrevin 2 (syb2), and the presynaptic membrane SNAREs syntaxin-1A and SNAP-25. However, it is controversially debated how many SNARE complexes are minimally needed for SV priming and fusion. To quantify this effective number, we measured the fluorescence responses from single fusing vesicles expressing pHluorin (pHl), a pH-sensitive variant of GFP, fused to the luminal domain of the vesicular SNARE syb2 (spH) in cultured hippocampal neurons lacking endogenous syb2. Fluorescence responses were quantal, with the unitary signals precisely corresponding to single pHluorin molecules. Using this approach we found that two copies of spH per SV fully rescued evoked fusion whereas SVs expressing only one spH were unable to rapidly fuse upon stimulation. Thus, two syb2 molecules and likely two SNARE complexes are necessary and sufficient for SV fusion during fast synaptic transmission.

  6. Structure of a micropipette-aspirated vesicle determined from the bending-energy model.

    PubMed

    Chen, Jeff Z Y

    2012-10-01

    The structure of the system consisting of an aspirating pipette and an aspirated vesicle is investigated with fixed total vesicle volume, total vesicle surface area, and aspirated volume fraction, based on the bending-energy model. Through an energetic consideration, the usage of an aspirated volume fraction can be converted to the aspirating pressure for the determination of a phase diagram; the procedure identifies a first-order transition, between a weakly aspirated state and the strongly aspirated state, as the pressure increases. The physical properties of the system are obtained from minimization of the bending energy by an implementation of the simulated annealing Monte Carlo procedure, which searches for a minimum in a multivariable space. An analysis of the hysteresis effects indicates that the experimentally observed aspirating and releasing critical pressures are related to the location of the spinodal points.

  7. Prime Suspect, Second Row Center

    ERIC Educational Resources Information Center

    Laird, Ellen A.

    2011-01-01

    His father had been hacked to death in his own bed with an ax the previous November. His mother was similarly brutalized and left for dead with her husband but survived. On the last Monday of that August, after several months and many investigative twists, turns, and fumbles, there sat the son--the prime suspect--in Ellen Laird's literature class,…

  8. The Search for Prime Numbers.

    ERIC Educational Resources Information Center

    Pomerance, Carl

    1982-01-01

    Until recently the testing of a 100-digit number to determine whether it is prime or composite could have taken a century. However, in the past two years a method has been developed enabling a computer to determine the primality of an arbitrary number in about 40 seconds of running time. (Author/JN)

  9. Prime Suspect, Second Row Center

    ERIC Educational Resources Information Center

    Laird, Ellen A.

    2011-01-01

    His father had been hacked to death in his own bed with an ax the previous November. His mother was similarly brutalized and left for dead with her husband but survived. On the last Monday of that August, after several months and many investigative twists, turns, and fumbles, there sat the son--the prime suspect--in Ellen Laird's literature class,…

  10. Prime Minister Pierre Trudeau and Cruise Missile Testing.

    ERIC Educational Resources Information Center

    Bennett, Paul W.

    1986-01-01

    Based on the 1983 controversy over cruise missile testing by the United States over Canadian air space, this article provides the text of an open letter to the people and an interview by Prime Minister Trudeau. Parenthetical comments inserted by the author point out contradiction contained in the two documents. (JDH)

  11. The Impact of Emotional Priming on MMPI-2 Scale Scores

    ERIC Educational Resources Information Center

    Lee, Tayla T. C.; Forbey, Johnathan D.; Ritchey, Kristin A.

    2011-01-01

    The current study investigated potential emotional priming effects on Minnesota Multiphasic Personality Inventory-2 (MMPI-2) scale scores. Participants included 98 college students who completed a personal narrative intended to induce temporary mood states, the MMPI-2, and a mood rating inventory. Results of the mood manipulation indicated that…

  12. The Impact of Emotional Priming on MMPI-2 Scale Scores

    ERIC Educational Resources Information Center

    Lee, Tayla T. C.; Forbey, Johnathan D.; Ritchey, Kristin A.

    2011-01-01

    The current study investigated potential emotional priming effects on Minnesota Multiphasic Personality Inventory-2 (MMPI-2) scale scores. Participants included 98 college students who completed a personal narrative intended to induce temporary mood states, the MMPI-2, and a mood rating inventory. Results of the mood manipulation indicated that…

  13. Evaluative Priming in the Pronunciation Task.

    PubMed

    Klauer, Karl Christoph; Becker, Manuel; Spruyt, Adriaan

    2016-01-01

    We replicated and extended a study by Spruyt and Hermans (2008) in which picture primes engendered an evaluative-priming effect on the pronunciation of target words. As preliminary steps, we assessed data reproducibility of the original study, conducted Pilot Study I to identify highly semantically related prime-target pairs, reanalyzed the original data excluding such pairs, conducted Pilot Study II to demonstrate that we can replicate traditional associative priming effects in the pronunciation task, and conducted Pilot Study III to generate relatively unrelated sets of prime pictures and target words. The main study comprised three between-participants conditions: (1) a close replication of the original study, (2) the same condition excluding highly related prime-target pairs, and (3) a condition based on the relatively unrelated sets of prime pictures and target words developed in Pilot Study III. There was little evidence for an evaluative priming effect independent of semantic relatedness.

  14. Hydrodynamic tether extrusion from ``gelly'' vesicles

    NASA Astrophysics Data System (ADS)

    Guevorkian, Karine; Kremer, Sebastien; Brochard-Wyart, Francoise

    2008-03-01

    Extrusion of cell tethers requires the detachment of the plasma membrane and can be used to probe the strength of membrane-cytoskeleton adhesion. We have studied the hydrodynamic extrusion of tethers from red blood cells [1] and developed a theoretical model based on permeation of lipids through the network of membrane proteins linked to the cytoskeleton [2]. Our aim here is to probe the model on biomimetic systems, namely lipid vesicles filled with artificial cytoskeleton made of synthetic or biological gels, where we can adjust the membrane-cytoskeleton coupling. The properties of tubes extruded from these ``gelly'' vesicles will be compared to simple vesicles on one hand, and to red blood cells or human carcinoid BON cells on the other. [1] N. Borghi et al, Biophys. J. 93 (2007) [2] F. Brochard-Wyart, et al, Proc. Natl. Acad. Sci. USA, 103 (2006)

  15. Directed vesicle transport by diffusio-osmosis

    NASA Astrophysics Data System (ADS)

    Michler, D.; Shahidzadeh, N.; Sprik, R.; Bonn, D.

    2015-04-01

    We present a study on surfactant vesicles that spontaneously move towards an oil droplet that is deposited on a glass substrate. Tracer particles in the surfactant solution show that the motion is not self-propelled: the vesicles are entrained by a macroscopic hydrodynamic flow. Measurements of the flow velocity suggest that the flow is of diffusio-osmotic nature. The surfactant is observed to move into the oil phase which creates a gradient in ion concentration in the vicinity of the droplet. As the diffusion coefficients of the surfactant's co- and counter-ions differ, a charge separation takes place and an electric field arises. This electric field then generates a hydrodynamic flow along the charged glass substrate in which the vesicles are entrained.

  16. Gel phase vesicles buckle into specific shapes.

    PubMed

    Quemeneur, François; Quilliet, Catherine; Faivre, Magalie; Viallat, Annie; Pépin-Donat, Brigitte

    2012-03-09

    Osmotic deflation of giant vesicles in the rippled gel phase P(β') gives rise to a large variety of novel faceted shapes. These shapes are also found from a numerical approach by using an elastic surface model. A shape diagram is proposed based on the model that accounts for the vesicle size and ratios of three mechanical constants: in-plane shear elasticity and compressibility (usually neglected) and out-of-plane bending of the membrane. The comparison between experimental and simulated vesicle morphologies reveals that they are governed by a typical elasticity length, of the order of 1   μm, and must be described with a large Poisson's ratio.

  17. Functionally polymerized surfactant vesicles: synthesis and characterization

    SciTech Connect

    Tundo, P.; Kippenberger, D.J.; Klahn, P.L.; Prieto, N.E.; Fendler, J.H.

    1982-01-27

    Bis(2-(10-undecenoyloxycarbony bromide, bis(2-(10-undecenoyloxycarbony (2-hydroxyethyl)methylammonium bromide, bis(2-(10-undecenoyloxycarbony acid, bis(2-(10-undecenoyloxycarbony allylbis(2-dodecanoyloxycarbon bromide, and dimethyl-n-hexadecyl (10-(p-vin decyl)ammonium bromide have been synthesized. The predominantly single compartment bilayer vesicles formed from these surfactants could be polymerized either by exposure to ultraviolet irradiation or by the use of azoisobutyronitrile as an initiator. The presence of vesicles (unpolymerized and polymeric) has been demonstrated by electron micrography, H/sup 1/ NMR, gel filtration, phase transition, turbidity changes, substrate entrapment, and permeability. Polymerized vesicles are considerably more stable and less permeable and have reduced rates of turbidity changes compared to their unpolymerized counterparts. 19 references.

  18. How neurosecretory vesicles release their cargo.

    PubMed

    Scalettar, Bethe A

    2006-04-01

    Neurons and related cell types often contain two major classes of neurosecretory vesicles, synaptic vesicles (SVs) and dense-core granules (DCGs), which store and release distinct cargo. SVs store and release classic neurotransmitters, which facilitate propagation of action potentials across the synaptic cleft, whereas DCGs transport, store, and release hormones, proteins, and neuropeptides, which facilitate neuronal survival, synaptic transmission, and learning. Over the past few years, there has been a major surge in our understanding of many of the key molecular mechanisms underlying cargo release from SVs and DCGs. This surge has been driven largely by the use of fluorescence microscopy (especially total internal reflection fluorescence microscopy) to visualize SVs or DCGs in living cells. This review highlights some of the recent insights into cargo release from neurosecretory vesicles provided by fluorescence microscopy, with emphasis on DCGs.

  19. Pulsatile Lipid Vesicles under Osmotic Stress

    NASA Astrophysics Data System (ADS)

    Chabanon, Morgan; Ho, James C. S.; Liedberg, Bo; Parikh, Atul N.; Rangamani, Padmini

    2017-04-01

    The response of lipid bilayers to osmotic stress is an important part of cellular function. Previously, in [Oglecka et al. 2014], we reported that cell-sized giant unilamellar vesicles (GUVs) exposed to hypotonic media, respond to the osmotic assault by undergoing a cyclical sequence of swelling and bursting events, coupled to the membrane's compositional degrees of freedom. Here, we seek to deepen our quantitative understanding of the essential pulsatile behavior of GUVs under hypotonic conditions, by advancing a comprehensive theoretical model for vesicle dynamics. The model quantitatively captures our experimentally measured swell-burst parameters for single-component GUVs, and reveals that thermal fluctuations enable rate dependent pore nucleation, driving the dynamics of the swell-burst cycles. We further identify new scaling relationships between the pulsatile dynamics and GUV properties. Our findings provide a fundamental framework that has the potential to guide future investigations on the non-equilibrium dynamics of vesicles under osmotic stress.

  20. Carbon Nanotubes Mediate Fusion of Lipid Vesicles.

    PubMed

    Bhaskara, Ramachandra M; Linker, Stephanie M; Vögele, Martin; Köfinger, Jürgen; Hummer, Gerhard

    2017-02-28

    The fusion of lipid membranes is opposed by high energetic barriers. In living organisms, complex protein machineries carry out this biologically essential process. Here we show that membrane-spanning carbon nanotubes (CNTs) can trigger spontaneous fusion of small lipid vesicles. In coarse-grained molecular dynamics simulations, we find that a CNT bridging between two vesicles locally perturbs their lipid structure. Their outer leaflets merge as the CNT pulls lipids out of the membranes, creating an hourglass-shaped fusion intermediate with still intact inner leaflets. As the CNT moves away from the symmetry axis connecting the vesicle centers, the inner leaflets merge, forming a pore that completes fusion. The distinct mechanism of CNT-mediated membrane fusion may be transferable, providing guidance in the development of fusion agents, e.g., for the targeted delivery of drugs or nucleic acids.

  1. Dynamics of fibers growing inside soft vesicles

    NASA Astrophysics Data System (ADS)

    Marenduzzo, D.; Orlandini, E.

    2007-11-01

    We present 3D stochastic dynamic simulations of the growth of a semiflexible polymer inside a soft vesicle. We find that very stiff fibers stall soon and lock the membrane into a strongly deformed prolate shape. Fibers of intermediate stiffness buckle and form a toroidal configuration which distorts the membrane into an oblate shape. Finally, more flexible polymers form massive spool-like condensates with ordered domains, while the vesicle inflates isotropically. We discuss our results with respect to observations on cell shape in sickle red blood cells, developing erythrocytes, and genome packing inside bacteriophages. We quantify how the force felt by the fiber tip, and the vesicle aspect ratio, change during growth, and we discuss possible "synthetic biology" experiments to validate our results.

  2. Ciliary Extracellular Vesicles: Txt Msg Organelles.

    PubMed

    Wang, Juan; Barr, Maureen M

    2016-04-01

    Cilia are sensory organelles that protrude from cell surfaces to monitor the surrounding environment. In addition to its role as sensory receiver, the cilium also releases extracellular vesicles (EVs). The release of sub-micron sized EVs is a conserved form of intercellular communication used by all three kingdoms of life. These extracellular organelles play important roles in both short and long range signaling between donor and target cells and may coordinate systemic responses within an organism in normal and diseased states. EV shedding from ciliated cells and EV-cilia interactions are evolutionarily conserved phenomena, yet remarkably little is known about the relationship between the cilia and EVs and the fundamental biology of EVs. Studies in the model organisms Chlamydomonas and Caenorhabditis elegans have begun to shed light on ciliary EVs. Chlamydomonas EVs are shed from tips of flagella and are bioactive. Caenorhabditis elegans EVs are shed and released by ciliated sensory neurons in an intraflagellar transport-dependent manner. Caenorhabditis elegans EVs play a role in modulating animal-to-animal communication, and this EV bioactivity is dependent on EV cargo content. Some ciliary pathologies, or ciliopathies, are associated with abnormal EV shedding or with abnormal cilia-EV interactions. Until the 21st century, both cilia and EVs were ignored as vestigial or cellular junk. As research interest in these two organelles continues to gain momentum, we envision a new field of cell biology emerging. Here, we propose that the cilium is a dedicated organelle for EV biogenesis and EV reception. We will also discuss possible mechanisms by which EVs exert bioactivity and explain how what is learned in model organisms regarding EV biogenesis and function may provide insight to human ciliopathies.

  3. Ciliary extracellular vesicles: Txt msg orgnlls

    PubMed Central

    Wang, Juan; Barr, Maureen M.

    2016-01-01

    Cilia are sensory organelles that protrude from cell surfaces to monitor the surrounding environment. In addition to its role as sensory receiver, the cilium also releases extracellular vesicles (EVs). The release of sub-micron sized EVs is a conserved form of intercellular communication used by all three kingdoms of life. These extracellular organelles play important roles in both short and long range signaling between donor and target cells and may coordinate systemic responses within an organism in normal and diseased states. EV shedding from ciliated cells and EV-cilia interactions are evolutionarily conserved phenomena, yet remarkably little is known about the relationship between the cilia and EVs and the fundamental biology of EVs. Studies in the model organisms Chlamydomonas and C. elegans have begun to shed light on ciliary EVs. Chlamydomonas EVs are shed from tips of flagella and are bioactive. C. elegans EVs are shed and released by ciliated sensory neurons in an intraflagellar transport (IFT)-dependent manner. C. elegans EVs play a role in modulating animal-to-animal communication, and this EV bioactivity is dependent on EV cargo content. Some ciliary pathologies, or ciliopathies, are associated with abnormal EV shedding or with abnormal cilia-EV interactions, suggest the cilium may be an important organelle as an EV donor or as an EV target. Until the past few decades, both cilia and EVs were ignored as vestigial or cellular junk. As research interest in these two organelles continues to gain momentum, we envision a new field of cell biology emerging. Here, we propose that the cilium is a dedicated organelle for EV biogenesis and EV reception. We will also discuss possible mechanisms by which EVs exert bioactivity and explain how what is learned in model organisms regarding EV biogenesis and function may provide insight to human ciliopathies. PMID:26983828

  4. Short-term synaptic depression and stochastic vesicle dynamics reduce and shape neuronal correlations.

    PubMed

    Rosenbaum, Robert; Rubin, Jonathan E; Doiron, Brent

    2013-01-01

    Correlated neuronal activity is an important feature in many neural codes, a neural correlate of a variety of cognitive states, as well as a signature of several disease states in the nervous system. The cellular and circuit mechanics of neural correlations is a vibrant area of research. Synapses throughout the cortex exhibit a form of short-term depression where increased presynaptic firing rates deplete neurotransmitter vesicles, which transiently reduces synaptic efficacy. The release and recovery of these vesicles are inherently stochastic, and this stochasticity introduces variability into the conductance elicited by depressing synapses. The impact of spiking and subthreshold membrane dynamics on the transfer of neuronal correlations has been studied intensively, but an investigation of the impact of short-term synaptic depression and stochastic vesicle dynamics on correlation transfer is lacking. We find that short-term synaptic depression and stochastic vesicle dynamics can substantially reduce correlations, shape the timescale over which these correlations occur, and alter the dependence of spiking correlations on firing rate. Our results show that short-term depression and stochastic vesicle dynamics need to be taken into account when modeling correlations in neuronal populations.

  5. Bioaccumulation of dietary 2,2{prime},4,4{prime},5,5{prime}-hexachlorobiphenyl and induction of hepatic arylhydrocarbon hydroxylase in rainbow trout (Oncorhynchus mykiss)

    SciTech Connect

    Costa, E.G. da; Curtis, L.R.

    1995-10-01

    Juvenile rainbow trout (Oncorhynchus mykiss) were fed either 5 or 20 {micro}g, 2,2{prime},4,4{prime},5,5{prime}-hexachlorobiphenyl (245-HxCB)/g diet (wet wt.) for 4,8, or 12 weeks. Hepatic xenobiotic-metabolizing enzyme activities and dietary 245-HxCB accumulation in liver, muscle, and remaining carcass were determined. Liver-to-body weight ratios were not altered by either of the two 245-HxCB concentrations. Relative growth rate increased with time but was not altered by 245-HxCB concentration. Bioaccumulation of 245-HxCB was dose and time dependent in all tissues without reaching apparent stayed state. Hepatic arylhydrocarbon hydroxylase (AHH) activities increased with 245-HxCB dose and with time. Ethoxyresorufin-O-deethylase (EROD) activities also increased in fish fed 20 {micro}g 245-HxCB/g diet. No 245-HxCB-induced changes in uridine diphosphoglucuronosyl transferase (UDP-DT) or NADPH-dytochrome-c reductase (NCCR) activities were determined. High-resolution GC-MS analysis of the 245-HxCB standard revealed trace (0.4--0.5%) contamination by two mono-ortho pentachlorobiphenyls (PnCBs): 2,3,3{prime},4,4{prime}-PnCB and 2,3,4,4{prime},5-PnCB. Total liver accumulation of these contaminants was inversely related with corresponding EROD and AHH activities and estimated to contribute minimally to their induction. Results from this study suggested that long-term dietary 245-HxCB exposure induced cytochrome P4501A activities in rainbow trout liver.

  6. Elastic energy of polyhedral bilayer vesicles

    NASA Astrophysics Data System (ADS)

    Haselwandter, Christoph A.; Phillips, Rob

    2011-06-01

    In recent experiments [M. Dubois, B. Demé, T. Gulik-Krzywicki, J.-C. Dedieu, C. Vautrin, S. Désert, E. Perez, and T. Zemb, Nature (London)NATUAS0028-083610.1038/35079541 411, 672 (2001)] the spontaneous formation of hollow bilayer vesicles with polyhedral symmetry has been observed. On the basis of the experimental phenomenology it was suggested [M. Dubois, V. Lizunov, A. Meister, T. Gulik-Krzywicki, J. M. Verbavatz, E. Perez, J. Zimmerberg, and T. Zemb, Proc. Natl. Acad. Sci. USAPNASA60027-842410.1073/pnas.0400837101 101, 15082 (2004)] that the mechanism for the formation of bilayer polyhedra is minimization of elastic bending energy. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. In agreement with experiments, and provided that excess amphiphiles exhibiting spontaneous curvature are present in sufficient quantity, we find that polyhedral bilayer vesicles can indeed be energetically favorable compared to spherical bilayer vesicles. Consistent with experimental observations we also find that the bending energy associated with the vertices of bilayer polyhedra can be locally reduced through the formation of pores. However, the stabilization of polyhedral bilayer vesicles over spherical bilayer vesicles relies crucially on molecular segregation of excess amphiphiles along the ridges rather than the vertices of bilayer polyhedra. Furthermore, our analysis implies that, contrary to what has been suggested on the basis of experiments, the icosahedron does not minimize elastic bending energy among arbitrary polyhedral shapes and sizes. Instead, we find that, for large polyhedron sizes, the snub dodecahedron and the snub cube both have lower total bending energies than the icosahedron.

  7. Toroidal membrane vesicles in spherical confinement

    NASA Astrophysics Data System (ADS)

    Bouzar, Lila; Menas, Ferhat; Müller, Martin Michael

    2015-09-01

    We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.

  8. Toroidal membrane vesicles in spherical confinement.

    PubMed

    Bouzar, Lila; Menas, Ferhat; Müller, Martin Michael

    2015-09-01

    We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.

  9. Semantic priming with product verification but not production.

    PubMed

    Campbell, Jamie I D

    2011-12-01

    Campbell and Reynvoet (2009) found that time to name a single-digit target was about 8 ms faster if preceded by a near prime (±1) compared to a far prime (at least ±3) when prime-digit pairs were interleaved with number comparisons (9↑3; name larger) and not when they were interleaved with multiplication problems (9×3; state product). This is consistent with the claim by previous researchers that magnitude comparison can enable a semantic pathway for digit naming whereas number-fact retrieval can inhibit it. To pursue this, the current study compared priming in the context of multiplication production (9×3=?) versus multiplication verification (e.g., 9×3=24, true or false). Multiplication production, but not verification, may inhibit semantic digit naming to reduce naming-related interference with verbal number production. Indeed, semantic priming of digit naming occurred only in verification and not production blocks. This supports the conclusion that multiplication production can inhibit semantic mediation of digit naming, which is enabled in other number processing tasks (e.g., comparison, verification) that do not compete with naming for verbal number production processes. PsycINFO Database Record (c) 2011 APA, all rights reserved.

  10. A small pool of vesicles maintains synaptic activity in vivo

    PubMed Central

    Denker, Annette; Bethani, Ioanna; Kröhnert, Katharina; Körber, Christoph; Horstmann, Heinz; Wilhelm, Benjamin G.; Barysch, Sina V.; Kuner, Thomas; Neher, Erwin; Rizzoli, Silvio O.

    2011-01-01

    Chemical synapses contain substantial numbers of neurotransmitter-filled synaptic vesicles, ranging from approximately 100 to many thousands. The vesicles fuse with the plasma membrane to release neurotransmitter and are subsequently reformed and recycled. Stimulation of synapses in vitro generally causes the majority of the synaptic vesicles to release neurotransmitter, leading to the assumption that synapses contain numerous vesicles to sustain transmission during high activity. We tested this assumption by an approach we termed cellular ethology, monitoring vesicle function in behaving animals (10 animal models, nematodes to mammals). Using FM dye photooxidation, pHluorin imaging, and HRP uptake we found that only approximately 1–5% of the vesicles recycled over several hours, in both CNS synapses and neuromuscular junctions. These vesicles recycle repeatedly, intermixing slowly (over hours) with the reserve vesicles. The latter can eventually release when recycling is inhibited in vivo but do not seem to participate under normal activity. Vesicle recycling increased only to ≈5% in animals subjected to an extreme stress situation (frog predation on locusts). Synapsin, a molecule binding both vesicles and the cytoskeleton, may be a marker for the reserve vesicles: the proportion of vesicles recycling in vivo increased to 30% in synapsin-null Drosophila. We conclude that synapses do not require numerous reserve vesicles to sustain neurotransmitter release and thus may use them for other purposes, examined in the accompanying paper. PMID:21903928

  11. Electrohydrodynamics of a compound vesicle under an AC electric field

    NASA Astrophysics Data System (ADS)

    Priti Sinha, Kumari; Thaokar, Rochish M.

    2017-07-01

    Compound vesicles are relevant as simplified models for biological cells as well as in technological applications such as drug delivery. Characterization of these compound vesicles, especially the inner vesicle, remains a challenge. Similarly their response to electric field assumes importance in light of biomedical applications such as electroporation. Fields lower than that required for electroporation cause electrodeformation in vesicles and can be used to characterize their mechanical and electrical properties. A theoretical analysis of the electrohydrodynamics of a compound vesicle with outer vesicle of radius R o and an inner vesicle of radius λ {{R}o} , is presented. A phase diagram for the compound vesicle is presented and elucidated using detailed plots of electric fields, free charges and electric stresses. The electrohydrodynamics of the outer vesicle in a compound vesicle shows a prolate-sphere and prolate-oblate-sphere shape transitions when the conductivity of the annular fluid is greater than the outer fluid, and vice-versa respectively, akin to single vesicle electrohydrodynamics reported in the literature. The inner vesicle in contrast shows sphere-prolate-sphere and sphere-prolate-oblate-sphere transitions when the inner fluid conductivity is greater and smaller than the annular fluid, respectively. Equations and methodology are provided to determine the bending modulus and capacitance of the outer as well as the inner membrane, thereby providing an easy way to characterize compound vesicles and possibly biological cells.

  12. Competition Effects in Phonological Priming: The Role of Mismatch Position between Primes and Targets

    ERIC Educational Resources Information Center

    Dufour, Sophie; Peereman, Ronald

    2009-01-01

    In three experiments, we examined lexical competition effects using the phonological priming paradigm in a shadowing task. Experiments 1A and 1B showed that an inhibitory priming effect occurred when the primes mismatched the targets on the last phoneme (/bagar/-/bagaj/). In contrast, a facilitatory priming effect was observed when the primes…

  13. Sandwich Priming: A Method for Overcoming the Limitations of Masked Priming by Reducing Lexical Competitor Effects

    ERIC Educational Resources Information Center

    Lupker, Stephen J.; Davis, Colin J.

    2009-01-01

    An orthographically similar masked nonword prime facilitates responding in a lexical decision task (Forster & Davis, 1984). Recently, this masked priming paradigm has been used to evaluate models of orthographic coding--models that attempt to quantify prime-target similarity. One general finding is that priming effects often do not occur when…

  14. Evidence for Episodic Retrieval of Inadequate Prime Responses in Auditory Negative Priming

    ERIC Educational Resources Information Center

    Mayr, Susanne; Buchner, Axel

    2006-01-01

    Four experiments are reported in which the mechanisms underlying auditory negative priming were investigated. In Experiments 1A and 1B, preprime-prime intervals and prime-probe intervals were manipulated.The ratio between the 2 intervals determined the size of the negative priming effect. Results are compatible with the episodic retrieval account,…

  15. Competition Effects in Phonological Priming: The Role of Mismatch Position between Primes and Targets

    ERIC Educational Resources Information Center

    Dufour, Sophie; Peereman, Ronald

    2009-01-01

    In three experiments, we examined lexical competition effects using the phonological priming paradigm in a shadowing task. Experiments 1A and 1B showed that an inhibitory priming effect occurred when the primes mismatched the targets on the last phoneme (/bagar/-/bagaj/). In contrast, a facilitatory priming effect was observed when the primes…

  16. Structural Priming and Second Language Learning

    ERIC Educational Resources Information Center

    Shin, Jeong-Ah; Christianson, Kiel

    2012-01-01

    Structural priming (or syntactic priming) is a speaker's tendency to reuse the same structural pattern as one that was previously encountered (Bock, 1986). This study investigated (a) whether the implicit learning processes involved in long-lag structural priming lead to differential second language (L2) improvement in producing two structural…

  17. Structural Priming and Second Language Learning

    ERIC Educational Resources Information Center

    Shin, Jeong-Ah; Christianson, Kiel

    2012-01-01

    Structural priming (or syntactic priming) is a speaker's tendency to reuse the same structural pattern as one that was previously encountered (Bock, 1986). This study investigated (a) whether the implicit learning processes involved in long-lag structural priming lead to differential second language (L2) improvement in producing two structural…

  18. Spatial priming in ecologically relevant reference frames.

    PubMed

    Tower-Richardi, Sarah M; Leber, Andrew B; Golomb, Julie D

    2016-01-01

    In recent years, researchers have observed many phenomena demonstrating how the visual system exploits spatial regularities in the environment in order to benefit behavior. In this paper, we question whether spatial priming can be considered one such phenomenon. Spatial priming is defined as a response time facilitation to a visual search target when its spatial position has been repeated in recent trials (Maljkovic & Nakayama, 1996, Perception & Psychophysics, 58, 977-991). Does this priming serve a behaviorally adaptive role or is it merely a byproduct of ongoing visual processing? Critically, an adaptive priming mechanism must actively transform visual inputs from native retinotopic (eye-centered) coordinates into ecologically relevant coordinates, e.g., spatiotopic (world-centered) and/or object-centered. In Experiment 1, we tested this hypothesis by having participants move their eyes between trials, which dissociated retinotopic and spatiotopic frames of reference. Results showed only weak retinotopic priming, but robust spatiotopic priming. The second experiment again had participants move their eyes between trials but also manipulated the placement of a grouped array of display objects from trial to trial. This allowed us to measure not just retinotopic and spatiotopic priming, but object-centered priming as well. Results from this experiment did not yield retinotopic priming but showed robust spatiotopic and object-centered priming. These findings demonstrate that spatial priming operates within ecologically relevant coordinate systems, and the findings support the notion that spatial priming serves an adaptive role in human behavior.

  19. Priming Lexical Stress in Reading Italian Aloud

    ERIC Educational Resources Information Center

    Sulpizio, Simone; Job, Remo; Burani, Cristina

    2012-01-01

    Two experiments using a lexical priming paradigm investigated how stress information is processed in reading Italian words. In both experiments, prime and target words either shared the stress pattern or they had different stress patterns. We expected that lexical activation of the prime would favour the assignment of congruent stress to the…

  20. Affective Priming with Associatively Acquired Valence

    ERIC Educational Resources Information Center

    Aguado, Luis; Pierna, Manuel; Saugar, Cristina

    2005-01-01

    Three experiments explored the effect of affectively congruent or incongruent primes on evaluation responses to positive or negative valenced targets (the "affective priming" effect). Experiment 1 replicated the basic affective priming effect with Spanish nouns: reaction time for evaluative responses (pleasant/unpleasant) were slower on…

  1. Affective Priming with Auditory Speech Stimuli

    ERIC Educational Resources Information Center

    Degner, Juliane

    2011-01-01

    Four experiments explored the applicability of auditory stimulus presentation in affective priming tasks. In Experiment 1, it was found that standard affective priming effects occur when prime and target words are presented simultaneously via headphones similar to a dichotic listening procedure. In Experiment 2, stimulus onset asynchrony (SOA) was…

  2. Affective Priming with Auditory Speech Stimuli

    ERIC Educational Resources Information Center

    Degner, Juliane

    2011-01-01

    Four experiments explored the applicability of auditory stimulus presentation in affective priming tasks. In Experiment 1, it was found that standard affective priming effects occur when prime and target words are presented simultaneously via headphones similar to a dichotic listening procedure. In Experiment 2, stimulus onset asynchrony (SOA) was…

  3. Priming Lexical Stress in Reading Italian Aloud

    ERIC Educational Resources Information Center

    Sulpizio, Simone; Job, Remo; Burani, Cristina

    2012-01-01

    Two experiments using a lexical priming paradigm investigated how stress information is processed in reading Italian words. In both experiments, prime and target words either shared the stress pattern or they had different stress patterns. We expected that lexical activation of the prime would favour the assignment of congruent stress to the…

  4. Automatic non-associative semantic priming: episodic affective priming of naming responses.

    PubMed

    Spruyt, Adriaan; Hermans, Dirk; De Houwer, Jan; Eelen, Paul

    2004-05-01

    Affective priming for associatively unrelated prime-target pairs was investigated using (a) the naming task, (b) a short stimulus onset asynchrony (250 ms), and (c) primes that had acquired their affective connotation during a differential evaluative conditioning procedure. Despite the fact that the primes and the targets were related on the affective dimension only, significant priming emerged. This finding indicates that mere affective overlap is sufficient to produce automatic priming. As such, our results are in line with theoretical accounts of automatic priming that are based on semantic relatedness.

  5. Semantic priming in the prime task effect: evidence of automatic semantic processing of distractors.

    PubMed

    Marí-Beffa, P; Fuentes, L J; Catena, A; Houghton, G

    2000-06-01

    The automaticity of the semantic processing of words has been questioned because of the reduction of semantic priming when the prime word is processed nonsemantically--for example, in letter search (the prime task effect). In two experiments, prime distractor words produced semantic priming in a subsequent lexical decision task, but with the direction of priming (positive or negative) depending on the prime task. Lexico-semantic tasks produced negative semantic priming, whereas letter search produced positive semantic priming. These results are discussed in terms of task-based inhibition. We argue that, given the results from the distractors, the absence of semantic priming does not indicate an absence of semantic activation but reflects the action of control processes on prepotent responses when less practiced responses are needed.

  6. Calcium uptake by intestinal brush border membrane vesicles. Comparison with in vivo calcium transport.

    PubMed Central

    Schedl, H P; Wilson, H D

    1985-01-01

    In prior studies, we examined kinetics of steady state in vivo transepithelial calcium transport in rat and hamster. The present studies related calcium uptake by the brush border to in vivo transport. We measured calcium uptake by brush border membrane vesicles from the two species. In the rat, our prior in vivo studies had shown that (a) calcium transport was mediated, (b) no nonmediated component was detectable, and (c) Vmax was 2.5 times greater in proximal than distal small intestine. In brush border membrane vesicles from the rat, Vmax for the saturable component of calcium uptake was again 2.5 times greater in proximal than distal intestine. Contrasting with in vivo studies, a major nonsaturable component was present in vesicles from proximal and distal small intestine. In the hamster, our previous in vivo studies had shown (1) both mediated and nonmediated components of calcium transport, (2) greater nonmediated transport in proximal than distal small intestines, and (3) Vmax for calcium transport twice as great in distal as in proximal small intestine. In the present study with brush border membrane vesicles from hamster, Vmax for saturable calcium transport was again twice as great in distal as in proximal small intestine. However, nonsaturable calcium transport rates relative to saturable rates were much greater with vesicles than in in vivo studies, and were greater in vesicles from distal than proximal small intestine. Since rates of saturable calcium uptake by brush border membrane vesicles parallel corresponding in vivo mediated transport rates, we conclude that the segmental rates of calcium transport in rat and hamster could be determined by brush border function. PMID:2997294

  7. Distinct Functions of Syntaxin-1 in Neuronal Maintenance, Synaptic Vesicle Docking, and Fusion in Mouse Neurons.

    PubMed

    Vardar, Gülçin; Chang, Shuwen; Arancillo, Marife; Wu, Yuan-Ju; Trimbuch, Thorsten; Rosenmund, Christian

    2016-07-27

    Neurotransmitter release requires the formation of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes by SNARE proteins syntaxin-1 (Stx1), synaptosomal-associated protein 25 (SNAP-25), and synaptobrevin-2 (Syb2). In mammalian systems, loss of SNAP-25 or Syb2 severely impairs neurotransmitter release; however, complete loss of function studies for Stx1 have been elusive due to the functional redundancy between Stx1 isoforms Stx1A and Stx1B and the embryonic lethality of Stx1A/1B double knock-out (DKO) mice. Here, we studied the roles of Stx1 in neuronal maintenance and neurotransmitter release in mice with constitutive or conditional deletion of Stx1B on an Stx1A-null background. Both constitutive and postnatal loss of Stx1 severely compromised neuronal viability in vivo and in vitro, indicating an obligatory role of Stx1 for maintenance of developing and mature neurons. Loss of Munc18-1, a high-affinity binding partner of Stx1, also showed severely impaired neuronal viability, but with a slower time course compared with Stx1A/1B DKO neurons, and exogenous Stx1A or Stx1B expression significantly delayed Munc18-1-dependent lethality. In addition, loss of Stx1 completely abolished fusion-competent vesicles and severely impaired vesicle docking, demonstrating its essential roles in neurotransmission. Putative partial SNARE complex assembly with the SNARE motif mutant Stx1A(AV) (A240V, V244A) was not sufficient to rescue neurotransmission despite full recovery of vesicle docking and neuronal survival. Together, these data suggest that Stx1 has independent functions in neuronal maintenance and neurotransmitter release and complete SNARE complex formation is required for vesicle fusion and priming, whereas partial SNARE complex formation is sufficient for vesicle docking and neuronal maintenance. Syntaxin-1 (Stx1) is a component of the synaptic vesicle soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE

  8. Comparison of Prime Movers Suitable for USMC Expeditionary Power Sources

    SciTech Connect

    Theiss, T J; Conklin, J. C.; Thomas, John F.; Armstrong, T. R.

    2000-04-18

    This report documents the results of the ORNL investigation into prime movers that would be desirable for the construction of a power system suitable for the United States Marine Corps (USMC) expeditionary forces under Operational Maneuvers From The Sea (OMFTS) doctrine. Discrete power levels of {approx}1, 5, 15, and 30 kW are considered. The only requirement is that the prime mover consumes diesel fuel. A brief description is given for the prime movers to describe their basic scientific foundations and relative advantages and disadvantages. A list of key attributes developed by ORNL has been weighted by the USMC to indicate the level of importance. A total of 14 different prime movers were scored by ORNL personnel in four size ranges (1,5, 15, & 30 kW) for their relative strength in each attribute area. The resulting weighted analysis was used to indicate which prime movers are likely to be suitable for USMC needs. No single engine or prime mover emerged as the clear-cut favorite but several engines scored as well or better than the diesel engine. At the higher load levels (15 & 30 kW), the results indicate that the open Brayton (gas turbine) is a relatively mature technology and likely a suitable choice to meet USMC needs. At the lower power levels, the situation is more difficult and the market alone is not likely to provide an optimum solution in the time frame desired (2010). Several prime movers should be considered for future developments and may be satisfactory; specifically, the Atkinson cycle, the open Brayton cycle (gas turbine), the 2-stroke diesel. The rotary diesel and the solid oxide fuel cell should be backup candidates. Of all these prime movers, the Atkinson cycle may well be the most suitable for this application but is an immature technology. Additional demonstrations of this engine will be conducted at ORNL. If this analysis is positive, then the performance of a generator set using this engine, the open Brayton and the 2-stroke diesel should

  9. The Bretherton Problem for a Vesicle

    NASA Astrophysics Data System (ADS)

    Barakat, Joseph; Spann, Andrew; Shaqfeh, Eric

    2016-11-01

    The motion of a lipid bilayer vesicle through a circular tube is investigated by singular perturbation theory in the limit of vanishing clearance. The vesicle is treated as a sac of fluid enclosed by a thin, elastic sheet that admits a bending stiffness. It is assumed that the vesicle is axisymmetric and swollen to a near-critical volume such that the clearance "e" between the membrane and the tube wall is very small. In this limit, bending resistance is of negligible importance compared to the isotropic tension, allowing the vesicle to be treated as a "no-slip bubble." The effective membrane tension is found to scale inversely with "e" raised to the 3/2 power with a comparatively weak Marangoni gradient. The extra pressure drop is found to have a leading contribution due to the cylindrical midsection, which scales inversely with "e," as well as a correction due to the end caps, which scales inversely with the square root of "e." The apparent viscosity is predicted as a unique function of the geometry. The theory exhibits excellent agreement with a simplified, "quasi-parallel" theory and with direct numerical simulations using the boundary element method. The results of this work are compared to those for bubbles, rigid particles, and red blood cells in confined flows.

  10. Hyperviscosity and hypofunction of the seminal vesicles.

    PubMed

    Gonzales, G F; Kortebani, G; Mazzolli, A B

    1993-01-01

    The study was designed to determine whether hyperviscosity of the semen sample is related to dysfunction of the male accessory glands. It was carried out on men who consecutively attended an infertility clinic between June 1989 and June 1991, and the men were grouped according to viscosity of semen samples (normal viscosity or higher viscosity). Semen samples from 229 infertility patients were studied. From these, 155 had normal viscosity and 74 showed hyperviscosity. The effect of hyperviscosity of semen samples on seminal quality and the function of the prostate was evaluated by acid phosphatase measurement, and the seminal vesicles by measurement of corrected fructose. Sperm motility (grades II-III), sperm vitality, and corrected fructose were significantly reduced in samples with high viscosity (p < .05). A high prevalence of hyperviscosity in semen samples was associated with only hypofunction of the seminal vesicles. In fact, 36.5% of subjects with hyperviscosity showed reduced levels of corrected fructose. The same association with hyperviscosity was not observed when only hypofunction of the prostate was present, or when hypofunction of both prostate and seminal vesicles was present (P:NS). Further analysis showed that high viscosity is observed mainly when corrected seminal fructose levels were below 1.5 mg/mL x 10(6) spz/mL. It would appear that hyperviscosity affects sperm motility and is associated with hypofunction of the seminal vesicles.

  11. Vesicle dynamics in shear and capillary flows

    NASA Astrophysics Data System (ADS)

    Noguchi, Hiroshi; Gompper, Gerhard

    2005-11-01

    The deformation of vesicles in flow is studied by a mesoscopic simulation technique, which combines multi-particle collision dynamics for the solvent with a dynamically triangulated surface model for the membrane. Shape transitions are investigated both in simple shear flows and in cylindrical capillary flows. We focus on reduced volumes, where the discocyte shape of fluid vesicles is stable, and the prolate shape is metastable. In simple shear flow at low membrane viscosity, the shear induces a transformation from discocyte to prolate with increasing shear rate, while at high membrane viscosity, the shear induces a transformation from prolate to discocyte, or tumbling motion accompanied by oscillations between these two morphologies. In capillary flow, at small flow velocities the symmetry axis of the discocyte is found not to be oriented perpendicular to the cylinder axis. With increasing flow velocity, a transition to a prolate shape occurs for fluid vesicles, while vesicles with shear-elastic membranes (like red blood cells) transform into a coaxial parachute-like shape.

  12. Preparation of vesicles entrapped lycopene extract.

    PubMed

    Luxsuwong, Dhitaree; Indranupakorn, Ratana; Wongtrakul, Paveena

    2014-01-01

    Lycopene, a lipophilic carotenoid, has been known as an effective antioxidant in supporting the cutaneous defensive system. However, it is unstable when exposed to light and water. In this study, lycopene was isolated from tomatoes and a vesicular delivery system was developed to entrap and stabilize the lycopene in the aqueous system. A simple process, maceration in ethyl acetate, was used to extract lycopene from the tomatoes. The extract was then chromatographed on the Sephadex LH20 column using acetone as a solvent system to yield 995 μg of lycopene per gram of dried tomato weight. The vesicular delivery system was prepared from a combination of ascorbic acid-6-palmitate (AP), cholesterol and dicetyl phosphate using a thin film hydration method. The formulation was composed of AP, cholesterol and dicetyl phosphate at a 44:44:12 molar ratio and with 2.12 μmol/ml of the isolated lycopene. Both blank vesicles and lycopene loaded vesicles were kept for a period of 3 months at 4±2°C and at the room temperature (28±2°C) to evaluate the effect of the encapsulation on the characteristic of the vesicles and on the antioxidant activity of the encapsulated lycopene. The result implied that lycopene could be stabilized in the vesicles and its scavenging activity against DPPH free radicals was superior to that of the free lycopene solution.

  13. Matrix vesicles: Are they anchored exosomes?

    PubMed

    Shapiro, Irving M; Landis, William J; Risbud, Makarand V

    2015-10-01

    Numerous studies have documented that matrix vesicles are unique extracellular membrane-bound microparticles that serve as initial sites for mineral formation in the growth plate and most other vertebrate mineralizing tissues. Microparticle generation is not confined to hard tissues, as cells in soft tissues generate similar structures; numerous studies have shown that a common type of extracellular particle, termed an exosome, a product of the endosomal pathway, shares many characteristics of matrix vesicles. Indeed, analyses of size, morphology and lipid and protein content indicate that matrix vesicles and exosomes are homologous structures. Such a possibility impacts our understanding of the biogenesis, processing and function of matrix vesicles (exosomes) in vertebrate hard tissues and explains in part how cells control the earliest stages of mineral deposition. Moreover, since exosomes influence a spectrum of functions, including cell-cell communication, it is suggested that this type of microparticle may provide a mechanism for the transfer of signaling molecules between cells within the growth plate and thereby regulate endochondral bone development and formation.

  14. Compartmentalization and Transport in Synthetic Vesicles

    PubMed Central

    Schmitt, Christine; Lippert, Anna H.; Bonakdar, Navid; Sandoghdar, Vahid; Voll, Lars M.

    2016-01-01

    Nanoscale vesicles have become a popular tool in life sciences. Besides liposomes that are generated from phospholipids of natural origin, polymersomes fabricated of synthetic block copolymers enjoy increasing popularity, as they represent more versatile membrane building blocks that can be selected based on their specific physicochemical properties, such as permeability, stability, or chemical reactivity. In this review, we focus on the application of simple and nested artificial vesicles in synthetic biology. First, we provide an introduction into the utilization of multicompartmented vesosomes as compartmentalized nanoscale bioreactors. In the bottom-up development of protocells from vesicular nanoreactors, the specific exchange of pathway intermediates across compartment boundaries represents a bottleneck for future studies. To date, most compartmented bioreactors rely on unspecific exchange of substrates and products. This is either based on changes in permeability of the coblock polymer shell by physicochemical triggers or by the incorporation of unspecific porin proteins into the vesicle membrane. Since the incorporation of membrane transport proteins into simple and nested artificial vesicles offers the potential for specific exchange of substances between subcompartments, it opens new vistas in the design of protocells. Therefore, we devote the main part of the review to summarize the technical advances in the use of phospholipids and block copolymers for the reconstitution of membrane proteins. PMID:26973834

  15. Vesicle deformation by microtubules: A phase diagram

    NASA Astrophysics Data System (ADS)

    Emsellem, Virginie; Cardoso, Olivier; Tabeling, Patrick

    1998-10-01

    The experimental investigation of vesicles deformed by the growth of encapsulated microtubules shows that the axisymmetric morphologies can be classified into ovals, lemons, φ, cherries, dumbbells, and pearls. A geometrical phase diagram is established. Numerical minimization of the elastic energy of the membrane reproduces satisfactorily well the observed morphologies and the corresponding phase diagram.

  16. Single-vesicle imaging reveals different transport mechanisms between glutamatergic and GABAergic vesicles.

    PubMed

    Farsi, Zohreh; Preobraschenski, Julia; van den Bogaart, Geert; Riedel, Dietmar; Jahn, Reinhard; Woehler, Andrew

    2016-02-26

    Synaptic transmission is mediated by the release of neurotransmitters, which involves exo-endocytotic cycling of synaptic vesicles. To maintain synaptic function, synaptic vesicles are refilled with thousands of neurotransmitter molecules within seconds after endocytosis, using the energy provided by an electrochemical proton gradient. However, it is unclear how transmitter molecules carrying different net charges can be efficiently sequestered while maintaining charge neutrality and osmotic balance. We used single-vesicle imaging to monitor pH and electrical gradients and directly showed different uptake mechanisms for glutamate and γ-aminobutyric acid (GABA) operating in parallel. In contrast to glutamate, GABA was exchanged for protons, with no other ions participating in the transport cycle. Thus, only a few components are needed to guarantee reliable vesicle filling with different neurotransmitters. Copyright © 2016, American Association for the Advancement of Science.

  17. Formation of polyhedral vesicles and polygonal membrane tubes induced by banana-shaped proteins

    NASA Astrophysics Data System (ADS)

    Noguchi, Hiroshi

    2015-12-01

    The shape transformations of fluid membranes induced by curved protein rods are studied using meshless membrane simulations. The rod assembly at low rod density induces a flat membrane tube and oblate vesicle. It is found that the polyhedral shapes are stabilized at high rod densities. The discrete shape transition between triangular and buckled discoidal tubes is obtained and their curvature energies are analyzed by a simple geometric model. For vesicles, triangular hosohedron and elliptic-disk shapes are formed in equilibrium, whereas tetrahedral and triangular prism shapes are obtained as metastable states.

  18. Maglev ready for prime time.

    SciTech Connect

    Rote, D. M.; Johnson, L. R.; Energy Systems

    2003-01-01

    Putting Maglev on Track' (Issues, Spring 1990) observed that growing airline traffic and associated delays were already significant and predicted that they would worsen. The article argued that a 300-mile-per-hour (mph) magnetic levitation (maglev) system integrated into airport and airline operations could be a part of the solution. Maglev was not ready for prime time in 1990, but it is now.

  19. Polyurethane Self-Priming Topcoats

    DTIC Science & Technology

    1992-06-23

    Approved for public release; distribution is unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT A corrosion -resistant coating which can be applied directly...57] ABSTRACT A corrosion -resistant coating which can be applied directly to a surface as a self-priming topcoat compris- ing from about 10 to 90... corrosion -inhibiting pigments consisting The invention described herein mav be manufactured 5 «»eniially of ar alkaline earth metal or zinc phosphate

  20. Dissecting docking and tethering of secretory vesicles at the target membrane

    PubMed Central

    Toonen, Ruud F; Kochubey, Olexiy; de Wit, Heidi; Gulyas-Kovacs, Attila; Konijnenburg, Bas; Sørensen, Jakob B; Klingauf, Jurgen; Verhage, Matthijs

    2006-01-01

    Secretory vesicles dock at their target in preparation for fusion. Using single-vesicle total internal reflection fluorescence microscopy in chromaffin cells, we show that most approaching vesicles dock only transiently, but that some are captured by at least two different tethering modes, weak and strong. Both vesicle delivery and tethering depend on Munc18-1, a known docking factor. By decreasing the amount of cortical actin by Latrunculin A application, morphological docking can be restored artificially in docking-deficient munc18-1 null cells, but neither strong tethering nor fusion, demonstrating that morphological docking is not sufficient for secretion. Deletion of the t-SNARE and Munc18-1 binding partner syntaxin, but not the v-SNARE synaptobrevin/VAMP, also reduces strong tethering and fusion. We conclude that docking vesicles either undock immediately or are captured by minimal tethering machinery and converted in a munc18-1/syntaxin-dependent, strongly tethered, fusion-competent state. PMID:16902411

  1. Multivalent ligand-receptor-mediated interaction of small filled vesicles with a cellular membrane

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.

    2017-07-01

    The ligand-receptor-mediated contacts of small sub-100-nm-sized lipid vesicles (or nanoparticles) with the cellular membrane are of interest in the contexts of cell-to-cell communication, endocytosis of membrane-coated virions, and drug (RNA) delivery. In all these cases, the interior of vesicles is filled by biologically relevant content. Despite the diversity of such systems, the corresponding ligand-receptor interaction possesses universal features. One of them is that the vesicle-membrane contacts can be accompanied by the redistribution of ligands and receptors between the contact and contact-free regions. In particular, the concentrations of ligands and receptors may become appreciably higher in the contact regions and their composition may there be different compared to that in the suspended state in the solution. A statistical model presented herein describes the corresponding distribution of various ligands and receptors and allows one to calculate the related change of the free energy with variation of the vesicle-engulfment extent. The results obtained are used to clarify the necessary conditions for the vesicle-assisted pathway of drug delivery.

  2. The effect of spontaneous curvature on a two-phase vesicle

    NASA Astrophysics Data System (ADS)

    Cox, Geoffrey; Lowengrub, John

    2015-03-01

    Vesicles are membrane-bound structures commonly known for their roles in cellular transport and the shape of a vesicle is determined by its surrounding membrane (lipid bilayer). When the membrane is composed of different lipids, it is natural for the lipids of similar molecular structure to migrate towards one another (via spinodal decomposition), creating a multi-phase vesicle. In this article, we consider a two-phase vesicle model which is driven by nature's propensity to maintain a minimal state of elastic energy. The model assumes a continuum limit, thereby treating the membrane as a closed three-dimensional surface. The main purpose of this study is to reveal the complexity of the Helfrich two-phase vesicle model with non-zero spontaneous curvature and provide further evidence to support the relevance of spontaneous curvature as a modelling parameter. In this paper, we illustrate the complexity of the Helfrich two-phase model by providing multiple examples of undocumented solutions and energy hysteresis. We also investigate the influence of spontaneous curvature on morphological effects and membrane phenomena such as budding and fusion.

  3. Material Studies of Lipid Vesicles in the Lα and Lα-Gel Coexistence Regimes

    PubMed Central

    Shoemaker, Scott D.; Vanderlick, T. Kyle

    2003-01-01

    In this work, we utilize micropipette aspiration and fluorescence imaging to examine the material properties of lipid vesicles made from mixtures of palmitoyloleoylphosphocholine (POPC) and dipalmitoylphosphatidylcholine (DPPC). At elevated temperatures/low DPPC fractions, these lipids are in a miscible liquid crystalline (Lα) state, whereas at lower temperatures/higher DPPC fractions they phase-separate into Lα and gel phases. We show that the elastic modulus, K, and critical tension, τc, of Lα vesicles are independent of DPPC fraction. However, as the sample temperature is increased from 15°C to 45°C, we measure decreases in both K and τc of 20% and 50%, respectively. The elasticity change is likely driven by a change in interfacial tension. We describe the reduction in critical tension using a simple model of thermally activated membrane pores. Vesicles with two-phase coexistence exhibit material properties that differ from Lα vesicles including critical tensions that are 20–40% lower. Fluorescence imaging of phase coexistent POPC/DPPC vesicles shows that the DPPC-rich domains exist in an extended network structure that exhibits characteristics of a solid. This gel network explains many of the unusual material properties of two-phase membranes. PMID:12547781

  4. Self-Assembly of Bilayer Vesicles Made of Saturated Long Chain Fatty Acids.

    PubMed

    Douliez, Jean-Paul; Houssou, Bérénice Houinsou; Fameau, A-Laure; Navailles, Laurence; Nallet, Frédéric; Grélard, Axelle; Dufourc, Erick J; Gaillard, Cédric

    2016-01-19

    Saturated long chain fatty acids (sLCFA, e.g., C14:0, C16:0, and C18:0) are potentially the greenest and cheapest surfactants naturally available. However, because aqueous sodium soaps of sLCFA are known to crystallize, the self-assembly of stable bilayer vesicles has not been reported yet. Here, by using such soaps in combination with guanidine hydrochloride (GuHCl), which has been shown recently to prevent crystallization, we were capable of producing stable bilayer vesicles made of sLCFA. The phase diagrams were established for a variety of systems showing that vesicles can form in a broad range of composition and pH. Both solid state NMR and small-angle neutron scattering allowed demonstrating that in such vesicles sLCFA are arranged in a bilayer structure which exhibits similar dynamic and structural properties as those of phospholipid membranes. We expect these vesicles to be of interest as model systems of protocells and minimal cells but also for various applications since fatty acids are potentially substitutes to phospholipids, synthetic surfactants, and polymers.

  5. Particle filtering for tracking of GLUT4 vesicles in TIRF microscpy

    NASA Astrophysics Data System (ADS)

    Wu, Xiangping; Liu, Xiaofang; Xu, Wenglong; Yan, Dandan; Chen, Yongli

    2009-10-01

    GLUT4 is responsible for insulin-stimulated glucose uptake into fat cells and description of the dynamic behavior of it can give insight in some working mechanisms and structures of these cells. Quantitative analysis of the dynamical process requires tracking of hundreds of GLUT4 vesicles characterized as bright spots in noisy image sequences. In this paper, a 3D tracking algorithm built in Bayesian probabilistic framework is put forward, combined with the unique features of the TIRF microscopy. A brightness-correction procedure is firstly applied to ensure that the intensity of a vesicle is constant along time and is only affected by spatial factors. Then, tracking is formalized as a state estimation problem and a developed particle filter integrated by a sub-optimizer that steers the particles towards a region with high likelihood is used. Once each tracked vesicle is located in image plane, the depth information of a granule can be indirectly inferred according to the exponential relationship between its intensity and its vertical position. The experimental results indicate that the vesicles are tracked well under different motion styles. More, the algorithm provides the depth information of the tracked vesicle.

  6. The effect of spontaneous curvature on a two-phase vesicle

    PubMed Central

    Cox, Geoffrey; Lowengrub, John

    2015-01-01

    Vesicles are membrane-bound structures commonly known for their roles in cellular transport and the shape of a vesicle is determined by its surrounding membrane (lipid bilayer). When the membrane is composed of different lipids, it is natural for the lipids of similar molecular structure to migrate towards one another (via spinodal decomposition), creating a multi-phase vesicle. In this article, we consider a two-phase vesicle model which is driven by nature’s propensity to maintain a minimal state of elastic energy. The model assumes a continuum limit, thereby treating the membrane as a closed three-dimensional surface. The main purpose of this study is to reveal the complexity of the Helfrich two-phase vesicle model with non-zero spontaneous curvature and provide further evidence to support the relevance of spontaneous curvature as a modelling parameter. In this paper, we illustrate the complexity of the Helfrich two-phase model by providing multiple examples of undocumented solutions and energy hysteresis. We also investigate the influence of spontaneous curvature on morphological effects and membrane phenomena such as budding and fusion. PMID:26097287

  7. Lattice-gas model for active vesicle transport by molecular motors with opposite polarities

    NASA Astrophysics Data System (ADS)

    Muhuri, Sudipto; Pagonabarraga, Ignacio

    2010-08-01

    We introduce a multispecies lattice-gas model for motor protein driven collective cargo transport on cellular filaments. We use this model to describe and analyze the collective motion of interacting vesicle cargos being carried by oppositely directed molecular motors, moving on a single biofilament. Building on a totally asymmetric exclusion process to characterize the motion of the interacting cargos, we allow for mass exchange with the environment, input, and output at filament boundaries and focus on the role of interconversion rates and how they affect the directionality of the net cargo transport. We quantify the effect of the various different competing processes in terms of nonequilibrium phase diagrams. The interplay of interconversion rates, which allow for flux reversal and evaporation-deposition processes, introduces qualitatively unique features in the phase diagrams. We observe regimes of three-phase coexistence, the possibility of phase re-entrance, and a significant flexibility in how the different phase boundaries shift in response to changes in control parameters. The moving steady-state solutions of this model allows for different possibilities for the spatial distribution of cargo vesicles, ranging from homogeneous distribution of vesicles to polarized distributions, characterized by inhomogeneities or shocks. Current reversals due to internal regulation emerge naturally within the framework of this model. We believe that this minimal model will clarify the understanding of many features of collective vesicle transport, apart from serving as the basis for building more exact quantitative models for vesicle transport relevant to various in vivo situations.

  8. Calcium regulates vesicle replenishment at the cone ribbon synapse.

    PubMed

    Babai, Norbert; Bartoletti, Theodore M; Thoreson, Wallace B

    2010-11-24

    Cones release glutamate-filled vesicles continuously in darkness, and changing illumination modulates this release. Because sustained release in darkness is governed by vesicle replenishment rates, we analyzed how cone membrane potential regulates replenishment. Synaptic release from cones was measured by recording postsynaptic currents in Ambystoma tigrinum horizontal or OFF bipolar cells evoked by depolarization of simultaneously voltage-clamped cones. We measured replenishment after attaining a steady state between vesicle release and replenishment using trains of test pulses. Increasing Ca(2+) currents (I(Ca)) by changing the test step from -30 to -10 mV increased replenishment. Lengthening -30 mV test pulses to match the Ca(2+) influx during 25 ms test pulses to -10 mV produced similar replenishment rates. Reducing Ca(2+) driving force by using test steps to +30 mV slowed replenishment. Using UV flashes to reverse inhibition of I(Ca) by nifedipine accelerated replenishment. Increasing [Ca(2+)](i) by flash photolysis of caged Ca(2+) also accelerated replenishment. Replenishment, but not the initial burst of release, was enhanced by using an intracellular Ca(2+) buffer of 0.5 mm EGTA rather than 5 mm EGTA, and diminished by 1 mm BAPTA. This suggests that although release and replenishment exhibited similar Ca(2+) dependencies, release sites are <200 nm from Ca(2+) channels but replenishment sites are >200 nm away. Membrane potential thus regulates replenishment by controlling Ca(2+) influx, principally by effects on replenishment mechanisms but also by altering releasable pool size. This in turn provides a mechanism for converting changes in light intensity into changes in sustained release at the cone ribbon synapse.

  9. KAPAO Prime: Design and Simulation

    NASA Astrophysics Data System (ADS)

    McGonigle, Lorcan; Choi, P. I.; Severson, S. A.; Spjut, E.

    2013-01-01

    KAPAO (KAPAO A Pomona Adaptive Optics instrument) is a dual-band natural guide star adaptive optics system designed to measure and remove atmospheric aberration over UV-NIR wavelengths from Pomona College’s telescope atop Table Mountain. We present here, the final optical system, KAPAO Prime, designed in Zemax Optical Design Software that uses custom off-axis paraboloid mirrors (OAPs) to manipulate light appropriately for a Shack-Hartman wavefront sensor, deformable mirror, and science cameras. KAPAO Prime is characterized by diffraction limited imaging over the full 81” field of view of our optical camera at f/33 as well as over the smaller field of view of our NIR camera at f/50. In Zemax, tolerances of 1% on OAP focal length and off-axis distance were shown to contribute an additional 4 nm of wavefront error (98% confidence) over the field of view of our optical camera; the contribution from surface irregularity was determined analytically to be 40nm for OAPs specified to λ/10 surface irregularity (632.8nm). Modeling of the temperature deformation of the breadboard in SolidWorks revealed 70 micron contractions along the edges of the board for a decrease of 75°F when applied to OAP positions such displacements from the optimal layout are predicted to contribute an additional 20 nanometers of wavefront error. Flexure modeling of the breadboard due to gravity is on-going. We hope to begin alignment and testing of KAPAO Prime in Q1 2013.

  10. KAPAO Prime: Design and Simulation

    NASA Astrophysics Data System (ADS)

    McGonigle, Lorcan

    2012-11-01

    KAPAO (KAPAO A Pomona Adaptive Optics instrument) is a dual-band natural guide star adaptive optics system designed to measure and remove atmospheric aberration from Pomona College's telescope atop Table Mountain. We present here, the final optical system, referred to as Prime, designed in Zemax Optical Design Software. Prime is characterized by diffraction limited imaging over the full 73'' field of view of our Andor Camera at f/33 as well as for our NIR Xenics camera at f/50. In Zemax, tolerances of 1% on OAP focal length and off-axis distance were shown to contribute an additional 4 nm of wavefront error (98% confidence) over the field of view of the Andor camera; the contribution from surface irregularity was determined analytically to be 40nm for OAPs specified to l/10 surface irregularity. Modeling of the temperature deformation of the breadboard in SolidWorks revealed 70 micron contractions along the edges of the board for a decrease of 75 F; when applied to OAP positions such displacements from the optimal layout are predicted to contribute an additional 20 nanometers of wavefront error. Flexure modeling of the breadboard due to gravity is on-going. We hope to begin alignment and testing of ``Prime'' in Q1 2013.

  11. Buoyancy Limitation of Filamentous Cyanobacteria under Prolonged Pressure due to the Gas Vesicles Collapse

    NASA Astrophysics Data System (ADS)

    Abeynayaka, Helayaye Damitha Lakmali; Asaeda, Takashi; Kaneko, Yasuko

    2017-08-01

    Freshwater cyanobacterium Pseudanabaena galeata were cultured in chambers under artificially generated pressures, which correspond to the hydrostatic pressures at deep water. Variations occurred in gas vesicles volume, and buoyancy state of cells under those conditions were analyzed at different time intervals (5 min, 1 day, and 5 days). Variations in gas vesicles morphology of cells were observed by transmission electron microscopy images. Settling velocity ( Vs) of cells which governs the buoyancy was observed with the aid of a modified optical microscope. Moreover, effects of the prolonged pressure on cell ballast composition (protein and polysaccharides) were examined. Elevated pressure conditions reduced the cell ballast and caused a complete disappearance of gas vesicles in Pseudanabaena galeata cells. Hence cyanobacteria cells were not able to float within the study period. Observations and findings of the study indicate the potential application of hydrostatic pressure, which naturally occurred in hypolimnion of lakes, to inhibit the re-suspension of cyanobacteria cells.

  12. Oscillatory phase separation in giant lipid vesicles induced by transmembrane osmotic differentials.

    PubMed

    Oglęcka, Kamila; Rangamani, Padmini; Liedberg, Bo; Kraut, Rachel S; Parikh, Atul N

    2014-10-15

    Giant lipid vesicles are closed compartments consisting of semi-permeable shells, which isolate femto- to pico-liter quantities of aqueous core from the bulk. Although water permeates readily across vesicular walls, passive permeation of solutes is hindered. In this study, we show that, when subject to a hypotonic bath, giant vesicles consisting of phase separating lipid mixtures undergo osmotic relaxation exhibiting damped oscillations in phase behavior, which is synchronized with swell-burst lytic cycles: in the swelled state, osmotic pressure and elevated membrane tension due to the influx of water promote domain formation. During bursting, solute leakage through transient pores relaxes the pressure and tension, replacing the domain texture by a uniform one. This isothermal phase transition--resulting from a well-coordinated sequence of mechanochemical events--suggests a complex emergent behavior allowing synthetic vesicles produced from simple components, namely, water, osmolytes, and lipids to sense and regulate their micro-environment.

  13. Microfluidic approaches for isolation, detection, and characterization of extracellular vesicles: Current status and future directions.

    PubMed

    Gholizadeh, Shima; Shehata Draz, Mohamed; Zarghooni, Maryam; Sanati-Nezhad, Amir; Ghavami, Saeid; Shafiee, Hadi; Akbari, Mohsen

    2017-05-15

    Extracellular vesicles (EVs) are cell-derived vesicles present in body fluids that play an essential role in various cellular processes, such as intercellular communication, inflammation, cellular homeostasis, survival, transport, and regeneration. Their isolation and analysis from body fluids have a great clinical potential to provide information on a variety of disease states such as cancer, cardiovascular complications and inflammatory disorders. Despite increasing scientific and clinical interest in this field, there are still no standardized procedures available for the purification, detection, and characterization of EVs. Advances in microfluidics allow for chemical sampling with increasingly high spatial resolution and under precise manipulation down to single molecule level. In this review, our objective is to give a brief overview on the working principle and examples of the isolation and detection methods with the potential to be used for extracellular vesicles. This review will also highlight the integrated on-chip systems for isolation and characterization of EVs.

  14. Buoyancy Limitation of Filamentous Cyanobacteria under Prolonged Pressure due to the Gas Vesicles Collapse.

    PubMed

    Abeynayaka, Helayaye Damitha Lakmali; Asaeda, Takashi; Kaneko, Yasuko

    2017-08-01

    Freshwater cyanobacterium Pseudanabaena galeata were cultured in chambers under artificially generated pressures, which correspond to the hydrostatic pressures at deep water. Variations occurred in gas vesicles volume, and buoyancy state of cells under those conditions were analyzed at different time intervals (5 min, 1 day, and 5 days). Variations in gas vesicles morphology of cells were observed by transmission electron microscopy images. Settling velocity (Vs) of cells which governs the buoyancy was observed with the aid of a modified optical microscope. Moreover, effects of the prolonged pressure on cell ballast composition (protein and polysaccharides) were examined. Elevated pressure conditions reduced the cell ballast and caused a complete disappearance of gas vesicles in Pseudanabaena galeata cells. Hence cyanobacteria cells were not able to float within the study period. Observations and findings of the study indicate the potential application of hydrostatic pressure, which naturally occurred in hypolimnion of lakes, to inhibit the re-suspension of cyanobacteria cells.

  15. What determines the direction of subliminal priming

    PubMed Central

    Jaśkowski, Piotr; Verleger, Rolf

    2008-01-01

    Masked stimuli (primes) can affect the preparation of a motor response to subsequently presented target stimuli. Reactions to the target can be facilitated (straight priming) or inhibited (inverse priming) when preceded by a compatible prime (calling for the same response) and also when preceded by an incompatible prime. Several hypotheses are currently under debate. These are the self-inhibition (SI) hypothesis, the object-updating (OU) hypothesis, and mask-triggered inhibition (MTI) hypothesis. All assume that the initial activation of the motor response is elicited by the prime according to its identity. This activation inevitably leads to straight priming in some cases and the mechanisms involved are undisputed. The hypotheses differ, however, as to why inverse priming occurs. The self-inhibition (SI) hypothesis assumes that the motor activation elicited by a prime is automatically followed by an inhibition phase, leading to inverse priming if three conditions are fulfilled: perceptual evidence for the prime has to be sufficiently strong, it has to be immediately removed by the mask, and the delay between the prime and target has to be long enough for inhibition to become effective. The object-updating (OU) hypothesis assumes that inverse priming is triggered by the mask, provided that it contains features calling for the alternative response (i.e. the one contrasting with the response induced by the prime). The MTI hypothesis assumes that the inhibitory phase is triggered by each successive stimulus which does not support the perceptual hypothesis provided by the prime. Based mostly on our own experiments, we argue that (1) attempts to manipulate the three factors required by the SI hypothesis imply changes of other variables and that (2) indeed, other variables seem to affect priming: prime-mask perceptual interaction and temporal position of the mask. These observations are in favor of the MTI hypothesis. A limiting factor for all three hypotheses is that

  16. Interfacial Recognition of Acetylcholine by an Amphiphilic p-Sulfonatocalix[8]arene Derivative Incorporated into Dimyristoyl Phosphatidylcholine Vesicles

    PubMed Central

    Jin, Takashi; Fujii, Fumihiko; Ooi, Yasuhiro

    2008-01-01

    Dodecyl ether derivatives 1-3 of p-sulfonatocalix[n]arene were incorporated into dimyristoyl phosphatidylcholine (DMPC) vesicles, and their binding abilities for acetylcholine (ACh) were examined by using steady-state fluorescence/fluorescence anisotropy and fluorescence correlation spectroscopy (FCS). For the detection of ACh binding to the DMPC vesicles containing 5 mol % of 1-3, competitive fluorophore displacement experiments were performed, where rhodamine 6G (Rh6G) was used as a fluorescent guest. The addition of Rh6G to the DMPC vesicles containing 3 resulted in a decrease in the fluorescence intensity of Rh6G with an increase of its fluorescence anisotropy, indicating that Rh6G binds to the DMPC-3 vesicles. In the case of DMPC-1 and DMPC-2 vesicles, significant changes in the fluorescence spectra of Rh6G were not observed. When ACh was added to the DMPC-3 vesicles in the presence of Rh6G ([3]/[Rh6G]=100), the fluorescence intensity of Rh6G increased with a decrease in its fluorescence anisotropy. From the analysis of fluorescence titration data, the association constants were determined to be 7.1×105 M-1 for Rh6G-3 complex and 1.1×102 M-1 for ACh-3 complex at the DMPC-3 vesicles. To get a direct evidence for the binding of Rh6G and its displacement by ACh at the DMPC-3 vesicles, diffusion times of the Rh6G were measured by using FCS. Binding selectivity of the DMPC-3 vesicles for ACh, choline, GABA, l-aspartic acid,l-glutamic acid, l-arginine, l-lysine, l-histamine and ammonium chloride was also evaluated using FCS. PMID:27873899

  17. Proteomic analysis of endocytic vesicles: Rab1a regulates motility of early endocytic vesicles

    PubMed Central

    Mukhopadhyay, Aparna; Nieves, Edward; Che, Fa-Yun; Wang, Jean; Jin, Lianji; Murray, John W.; Gordon, Kristie; Angeletti, Ruth Hogue; Wolkoff, Allan W.

    2011-01-01

    Texas-Red–asialoorosomucoid (ASOR) fluorescence-sorted early and late endocytic vesicles from rat liver were subjected to proteomic analysis with the aim of identifying functionally important proteins. Several Rab GTPases, including Rab1a, were found. The present study immunolocalized Rab1a to early and late endocytic vesicles and examined its potential role in endocytosis. Huh7 cells with stable knockdown of Rab1a exhibited reduced endocytic processing of ASOR. This correlated with the finding that Rab1a antibody reduced microtubule-based motility of rat-liver-derived early but not late endocytic vesicles in vitro. The inhibitory effect of Rab1a antibody was observed to be specifically towards minus-end-directed motility. Total and minus-end-directed motility was also reduced in early endocytic vesicles prepared from Rab1a-knockdown cells. These results corresponded with virtual absence of the minus-end-directed kinesin Kifc1 from early endocytic vesicles in Rab1a knockdown cells and imply that Rab1a regulates minus-end-directed motility largely by recruiting Kifc1 to early endocytic vesicles. PMID:21303926

  18. In vitro fusion between Saccharomyces cerevisiae secretory vesicles and cytoplasmic-side-out plasma membrane vesicles.

    PubMed Central

    Arrastua, Lorena; San Sebastian, Eider; Quincoces, Ana F; Antony, Claude; Ugalde, Unai

    2003-01-01

    The final step in the secretory pathway, which is the fusion event between secretory vesicles and the plasma membrane, was reconstructed using highly purified secretory vesicles and cytoplasmic-side-out plasma membrane vesicles from the yeast Saccharomyces cerevisiae. Both organelle preparations were obtained from a sec 6-4 temperature-sensitive mutant. Fusion was monitored by means of a fluorescence assay based on the dequenching of the lipophilic fluorescent probe octadecylrhodamine B-chloride (R18). The probe was incorporated into the membrane of secretory vesicles, and it diluted in unlabelled cytoplasmic-side-out plasma membrane vesicles as the fusion process took place. The obtained experimental dequenching curves were found by mathematical analysis to consist of two independent but simultaneous processes. Whereas one of them reflected the fusion process between both vesicle populations as confirmed by its dependence on the assay conditions, the other represented a non-specific transfer of the probe. The fusion process may now be examined in detail using the preparation, validation and analytical methods developed in this study. PMID:12435271

  19. Endo-lysosomal vesicles positive for Rab7 and LAMP1 are terminal vesicles for the transport of dextran.

    PubMed

    Humphries, William H; Szymanski, Craig J; Payne, Christine K

    2011-01-01

    The endo-lysosomal pathway is essential for intracellular transport and the degradation of extracellular cargo. The relationship between three populations of endo-lysosomal vesicles--Rab7-positive, LAMP1-positive, and both Rab7- and LAMP1-postive--was probed with fluorescence microscopy and single particle tracking. Of specific interest was determining if these vesicles were intermediate or terminal vesicles in the transport of extracellular cargo. We find that the major organelle in the endo-lysosomal pathway, both in terms of population and cargo transport, is positive for Rab7 and LAMP1. Dextran, a fluid phase cargo, shifts from localization within all three populations of vesicles at 30 minutes and 1 hour to primarily LAMP1- and Rab7/LAMP1-vesicles at longer times. This demonstrates that LAMP1- and Rab7/LAMP1-vesicles are terminal vesicles in the endo-lysosomal pathway. We tested two possible mechanisms for this distribution of cargo, delivery to mannose 6-phosphate receptor (M6PR)-negative vesicles and the fusion dynamics of individual vesicles. We find no correlation with M6PR but do find that Rab7-vesicles undergo significantly fewer fusion events than LAMP1- or Rab7/LAMP1-vesicles suggesting that the distribution of fluid phase cargo is driven by vesicle dynamics.

  20. Relational integrativity of prime-target pairs moderates congruity effects in evaluative priming.

    PubMed

    Ihmels, Max; Freytag, Peter; Fiedler, Klaus; Alexopoulos, Theodore

    2016-05-01

    In evaluative priming, positive or negative primes facilitate reactions to targets that share the same valence. While this effect is commonly explained as reflecting invariant structures in semantic long-term memory or in the sensorimotor system, the present research highlights the role of integrativity in evaluative priming. Integrativity refers to the ease of integrating two concepts into a new meaningful compound representation. In extended material tests using paired comparisons from two pools of positive and negative words, we show that evaluative congruity is highly correlated with integrativity. Therefore, in most priming studies, congruity and integrativity are strongly confounded. When both aspects are disentangled by manipulating congruity and integrativity orthogonally, three priming experiments show that evaluative-priming effects were confined to integrative prime-target pairs. No facilitation of prime-congruent targets was obtained for non-integrative stimuli. These findings are discussed from a broader perspective on priming conceived as flexible, context-dependent, and serving a generative adaptation function.