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Sample records for trp channel structure

  1. TRP channels in kidney disease.

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    Hsu, Y.J.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2007-01-01

    Mammalian TRP channel proteins form six-transmembrane cation-permeable channels that may be grouped into six subfamilies on the basis of amino acid sequence homology (TRPC, TRPV, TRPM, TRPA, TRPP, and TRPML). Recent studies of TRP channels indicate that they are involved in numerous fundamental cell

  2. Dawning of a new era in TRP channel structural biology by cryo-electron microscopy.

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    Madej, M Gregor; Ziegler, Christine M

    2018-02-01

    Cryo-electron microscopy (cryo-EM) permits the determination of atomic protein structures by averaging large numbers of individual projection images recorded at cryogenic temperatures-a method termed single-particle analysis. The cryo-preservation traps proteins within a thin glass-like ice layer, making literally a freeze image of proteins in solution. Projections of randomly adopted orientations are merged to reconstruct a 3D density map. While atomic resolution for highly symmetric viruses was achieved already in 2009, the development of new sensitive and fast electron detectors has enabled cryo-EM for smaller and asymmetrical proteins including fragile membrane proteins. As one of the most important structural biology methods at present, cryo-EM was awarded in October 2017 with the Nobel Prize in Chemistry. The molecular understanding of Transient-Receptor-Potential (TRP) channels has been boosted tremendously by cryo-EM single-particle analysis. Several near-atomic and atomic structures gave important mechanistic insights, e.g., into ion permeation and selectivity, gating, as well as into the activation of this enigmatic and medically important membrane protein family by various chemical and physical stimuli. Lastly, these structures have set the starting point for the rational design of TRP channel-targeted therapeutics to counteract life-threatening channelopathies. Here, we attempt a brief introduction to the method, review the latest advances in cryo-EM structure determination of TRP channels, and discuss molecular insights into the channel function based on the wealth of TRP channel cryo-EM structures.

  3. Post-Translational Modifications of TRP Channels

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    Olaf Voolstra

    2014-04-01

    Full Text Available Transient receptor potential (TRP channels constitute an ancient family of cation channels that have been found in many eukaryotic organisms from yeast to human. TRP channels exert a multitude of physiological functions ranging from Ca2+ homeostasis in the kidney to pain reception and vision. These channels are activated by a wide range of stimuli and undergo covalent post-translational modifications that affect and modulate their subcellular targeting, their biophysical properties, or channel gating. These modifications include N-linked glycosylation, protein phosphorylation, and covalent attachment of chemicals that reversibly bind to specific cysteine residues. The latter modification represents an unusual activation mechanism of ligand-gated ion channels that is in contrast to the lock-and-key paradigm of receptor activation by its agonists. In this review, we summarize the post-translational modifications identified on TRP channels and, when available, explain their physiological role.

  4. Mechanisms of Thermosensation in TRP Channels

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    Talavera, Karel; Voets, Thomas; Nilius, Bernd

    The transient receptor potential (TRP) superfamily encompasses a large number of cationic channels that are modulated by a wide variety of physical and chemical stimuli. A notorious subgroup of TRP channels, dubbed thermoTRPs, shows a dramatic dependence on temperature, which can be up to tenfold higher than that of classical ionic channels. Consequently, some thermoTRPs are thought to have a prominent role in the mechanisms of thermosensation and thermoregulation. However, the mechanisms underlying the high temperature sensitivity of thermoTRP activation are, for the most part, obscure. Only four out of the nine thermoTRPs known so far are sufficiently well characterised to allow a comprehensive model to be put forward. Temperature modulates the gating of TRPM8, TRPV1, TRPM4 and TRPM5 by shifting the voltage dependence of channel activation towards more negative potentials, which can be accounted for by a model in which voltage-dependent gating is directly affected by temperature. Heat activation of TRPV3 seems to be consistent with this mechanism, although a modification of the pore may also take place. For TRPV4, it has been proposed that an, as yet unidentified, diffusible ligand mediates activation by heat. The mechanisms for TRPV2, TRPA1 and TRPM2 are still unknown.

  5. Role of TRP channels in the cardiovascular system.

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    Yue, Zhichao; Xie, Jia; Yu, Albert S; Stock, Jonathan; Du, Jianyang; Yue, Lixia

    2015-02-01

    The transient receptor potential (TRP) superfamily consists of a large number of nonselective cation channels with variable degree of Ca(2+)-permeability. The 28 mammalian TRP channel proteins can be grouped into six subfamilies: canonical, vanilloid, melastatin, ankyrin, polycystic, and mucolipin TRPs. The majority of these TRP channels are expressed in different cell types including both excitable and nonexcitable cells of the cardiovascular system. Unlike voltage-gated ion channels, TRP channels do not have a typical voltage sensor, but instead can sense a variety of other stimuli including pressure, shear stress, mechanical stretch, oxidative stress, lipid environment alterations, hypertrophic signals, and inflammation products. By integrating multiple stimuli and transducing their activity to downstream cellular signal pathways via Ca(2+) entry and/or membrane depolarization, TRP channels play an essential role in regulating fundamental cell functions such as contraction, relaxation, proliferation, differentiation, and cell death. With the use of targeted deletion and transgenic mouse models, recent studies have revealed that TRP channels are involved in numerous cellular functions and play an important role in the pathophysiology of many diseases in the cardiovascular system. Moreover, several TRP channels are involved in inherited diseases of the cardiovascular system. This review presents an overview of current knowledge concerning the physiological functions of TRP channels in the cardiovascular system and their contributions to cardiovascular diseases. Ultimately, TRP channels may become potential therapeutic targets for cardiovascular diseases. Copyright © 2015 the American Physiological Society.

  6. TRP channels: sensors and transducers of gasotransmitter signals

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    Nobuaki eTakahashi

    2012-08-01

    Full Text Available The transient receptor potential (trp gene superfamily encodes cation channels that act as multimodal sensors for a wide variety of stimuli from outside and inside the cell. Upon sensing, they transduce electrical and Ca2+ signals via their cation channel activities. These functional features of TRP channels allow the body to react and adapt to different forms of environmental changes. Indeed, members of one class of TRP channels have emerged as sensors of gaseous messenger molecules that control various cellular processes. Nitric oxide (NO, a vasoactive gaseous molecule, regulates TRP channels directly via cysteine S-nitrosylation or indirectly via cGMP/PKG-dependent phosphorylation. Recent studies have revealed that changes in the availability of molecular oxygen (O2 also control the activation of TRP channels. Anoxia induced by O2-glucose deprivation and severe hypoxia (1% O2 activates TRPM7 and TRPC6, respectively, whereas TRPA1 has recently been identified as a novel sensor of hyperoxia and mild hypoxia (15% O2 in vagal and sensory neurons. TRPA1 also detects other gaseous molecules such as hydrogen sulfide (H2S and carbon dioxide (CO2. In this review, we focus on how signaling by gaseous molecules is sensed and integrated by TRP channels.

  7. Modulation of TRP channels by resveratrol and other stilbenoids

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    Yu Lina

    2013-02-01

    Full Text Available Abstract Background Resveratrol (3,5,4’ - trihydroxy-trans-stilbene, a widely distributed natural stilbenoid, was proposed to account for the unique effects of red wine on life span and health. It has been reported to possess various biological and pharmacological activities, such as anti-oxidant, anti-inflammatory, and anti-carcinogenic effects. Here, using whole-cell patch-clamp techniques and behavioral analyses, we investigated whether resveratrol and other stilbenoids can modulate TRP channels in sensory neurons in vitro, and have analgesic effects in vivo. Results We found that resveratrol dose-dependently suppressed the allyl isothiocyanate (AITC-induced currents (IAITC in HEK293 cells that express TRPA1, as well as in rat dorsal root ganglion (DRG neurons. Instead, pinosylvin methyl ether (PME, another derivate of stilbene which has a similar structure to resveratrol, dose-dependently blocked the capsaicin-induced currents (ICAP in HEK293 cells that express TRPV1 as well as in DRG neurons. Interestingly, resveratrol had no inhibitory effect on the ICAP, and PME had no effect on the IAITC. Otherwise, trans-stilbene showed no any effect on IAITC or ICAP. The concentration response curve of AITC showed that resveratrol inhibited the action of TRPA1 not by changing the EC50, but by suppressing the AITC-induced maximum response. By contrast, the inhibition of TRPV1 by PME did not change the capsaicin-induced maximum response but did cause a right shift of the EC50. Moreover, pre-administration of resveratrol suppressed intraplantar injections of AITC-evoked nocifensive behaviors, as well as that PME suppressed capsaicin-evoked one. Conclusions These data suggest that resveratrol and other stilbenoids may have an inhibitory effect on TRP channels. In addition, these stilbenoids modulate TRP channel activity in different ways.

  8. Evolutionary conservation and changes in insect TRP channels

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    Tominaga Makoto

    2009-09-01

    Full Text Available Abstract Background TRP (Transient Receptor Potential channels respond to diverse stimuli and thus function as the primary integrators of varied sensory information. They are also activated by various compounds and secondary messengers to mediate cell-cell interactions as well as to detect changes in the local environment. Their physiological roles have been primarily characterized only in mice and fruit flies, and evolutionary studies are limited. To understand the evolution of insect TRP channels and the mechanisms of integrating sensory inputs in insects, we have identified and compared TRP channel genes in Drosophila melanogaster, Bombyx mori, Tribolium castaneum, Apis mellifera, Nasonia vitripennis, and Pediculus humanus genomes as part of genome sequencing efforts. Results All the insects examined have 2 TRPV, 1 TRPN, 1 TRPM, 3 TRPC, and 1 TRPML subfamily members, demonstrating that these channels have the ancient origins in insects. The common pattern also suggests that the mechanisms for detecting mechanical and visual stimuli and maintaining lysosomal functions may be evolutionarily well conserved in insects. However, a TRPP channel, the most ancient TRP channel, is missing in B. mori, A. mellifera, and N. vitripennis. Although P. humanus and D. melanogaster contain 4 TRPA subfamily members, the other insects have 5 TRPA subfamily members. T. castaneum, A. mellifera, and N. vitripennis contain TRPA5 channels, which have been specifically retained or gained in Coleoptera and Hymenoptera. Furthermore, TRPA1, which functions for thermotaxis in Drosophila, is missing in A. mellifera and N. vitripennis; however, they have other Hymenoptera-specific TRPA channels (AmHsTRPA and NvHsTRPA. NvHsTRPA expressed in HEK293 cells is activated by temperature increase, demonstrating that HsTRPAs function as novel thermal sensors in Hymenoptera. Conclusion The total number of insect TRP family members is 13-14, approximately half that of mammalian TRP

  9. Sub-cellular distribution and translocation of TRP channels.

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    Toro, Carlos A; Arias, Luis A; Brauchi, Sebastian

    2011-01-01

    Cellular electrical activity is the result of a highly complex processes that involve the activation of ion channel proteins. Ion channels make pores on cell membranes that rapidly transit between conductive and non-conductive states, allowing different ions to flow down their electrochemical gradients across cell membranes. In the case of neuronal cells, ion channel activity orchestrates action potentials traveling through axons, enabling electrical communication between cells in distant parts of the body. Somatic sensation -our ability to feel touch, temperature and noxious stimuli- require ion channels able to sense and respond to our peripheral environment. Sensory integration involves the summing of various environmental cues and their conversion into electrical signals. Members of the Transient Receptor Potential (TRP) family of ion channels have emerged as important mediators of both cellular sensing and sensory integration. The regulation of the spatial and temporal distribution of membrane receptors is recognized as an important mechanism for controlling the magnitude of the cellular response and the time scale on which cellular signaling occurs. Several studies have shown that this mechanism is also used by TRP channels to modulate cellular response and ultimately fulfill their physiological function as sensors. However, the inner-working of this mode of control for TRP channels remains poorly understood. The question of whether TRPs intrinsically regulate their own vesicular trafficking or weather the dynamic regulation of TRP channel residence on the cell surface is caused by extrinsic changes in the rates of vesicle insertion or retrieval remain open. This review will examine the evidence that sub-cellular redistribution of TRP channels plays an important role in regulating their activity and explore the mechanisms that control the trafficking of vesicles containing TRP channels.

  10. TRP ion channels in thermosensation, thermoregulation and metabolism

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    Wang, Hong; Siemens, Jan

    2015-01-01

    In humans, the TRP superfamily of cation channels includes 27 related molecules that respond to a remarkable variety of chemical and physical stimuli. While physiological roles for many TRP channels remain unknown, over the past years several have been shown to function as molecular sensors in organisms ranging from yeast to humans. In particular, TRP channels are now known to constitute important components of sensory systems, where they participate in the detection or transduction of osmotic, mechanical, thermal, or chemosensory stimuli. We here summarize our current understanding of the role individual members of this versatile receptor family play in thermosensation and thermoregulation, and also touch upon their immerging role in metabolic control. PMID:27227022

  11. Identification and characterization of hydrophobic gate residues in TRP channels.

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    Zheng, Wang; Hu, Ruikun; Cai, Ruiqi; Hofmann, Laura; Hu, Qiaolin; Fatehi, Mohammad; Long, Wentong; Kong, Tim; Tang, Jingfeng; Light, Peter; Flockerzi, Veit; Cao, Ying; Chen, Xing-Zhen

    2018-02-01

    Transient receptor potential (TRP) channels, subdivided into 6 subfamilies in mammals, have essential roles in sensory physiology. They respond to remarkably diverse stimuli, comprising thermal, chemical, and mechanical modalities, through opening or closing of channel gates. In this study, we systematically substituted the hydrophobic residues within the distal fragment of pore-lining helix S6 with hydrophilic residues and, based on Xenopus oocyte and mammalian cell electrophysiology and a hydrophobic gate theory, identified hydrophobic gates in TRPV6/V5/V4/C4/M8. We found that channel activity drastically increased when TRPV6 Ala616 or Met617 or TRPV5 Ala576 or Met577 , but not any of their adjacent residues, was substituted with hydrophilic residues. Channel activity strongly correlated with the hydrophilicity of the residues at those sites, suggesting that consecutive hydrophobic residues TRPV6 Ala616-Met617 and TRPV5 Ala576-Met577 form a double-residue gate in each channel. By the same strategy, we identified a hydrophobic single-residue gate in TRPV4 Iso715 , TRPC4 Iso617 , and TRPM8 Val976 . In support of the hydrophobic gate theory, hydrophilic substitution at the gate site, which removes the hydrophobic gate seal, substantially increased the activity of TRP channels in low-activity states but had little effect on the function of activated channels. The double-residue gate channels were more sensitive to small changes in the gate's hydrophobicity or size than single-residue gate channels. The unconventional double-reside gating mechanism in TRP channels may have been evolved to respond especially to physiologic stimuli that trigger relatively small gate conformational changes.-Zheng, W., Hu, R., Cai, R., Hofmann, L., Hu, Q., Fatehi, M., Long, W., Kong, T., Tang, J., Light, P., Flockerzi, V., Cao, Y., Chen, X.-Z. Identification and characterization of hydrophobic gate residues in TRP channels.

  12. TRP Channels as Therapeutic Targets in Diabetes and Obesity

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    Andrea Zsombok

    2016-08-01

    Full Text Available During the last three to four decades the prevalence of obesity and diabetes mellitus has greatly increased worldwide, including in the United States. Both the short- and long-term forecasts predict serious consequences for the near future, and encourage the development of solutions for the prevention and management of obesity and diabetes mellitus. Transient receptor potential (TRP channels were identified in tissues and organs important for the control of whole body metabolism. A variety of TRP channels has been shown to play a role in the regulation of hormone release, energy expenditure, pancreatic function, and neurotransmitter release in control, obese and/or diabetic conditions. Moreover, dietary supplementation of natural ligands of TRP channels has been shown to have potential beneficial effects in obese and diabetic conditions. These findings raised the interest and likelihood for potential drug development. In this mini-review, we discuss possibilities for better management of obesity and diabetes mellitus based on TRP-dependent mechanisms.

  13. Transient receptor potential (TRP gene superfamily encoding cation channels

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    Pan Zan

    2011-01-01

    Full Text Available Abstract Transient receptor potential (TRP non-selective cation channels constitute a superfamily, which contains 28 different genes. In mammals, this superfamily is divided into six subfamilies based on differences in amino acid sequence homology between the different gene products. Proteins within a subfamily aggregate to form heteromeric or homomeric tetrameric configurations. These different groupings have very variable permeability ratios for calcium versus sodium ions. TRP expression is widely distributed in neuronal tissues, as well as a host of other tissues, including epithelial and endothelial cells. They are activated by environmental stresses that include tissue injury, changes in temperature, pH and osmolarity, as well as volatile chemicals, cytokines and plant compounds. Their activation induces, via intracellular calcium signalling, a host of responses, including stimulation of cell proliferation, migration, regulatory volume behaviour and the release of a host of cytokines. Their activation is greatly potentiated by phospholipase C (PLC activation mediated by coupled GTP-binding proteins and tyrosine receptors. In addition to their importance in maintaining tissue homeostasis, some of these responses may involve various underlying diseases. Given the wealth of literature describing the multiple roles of TRP in physiology in a very wide range of different mammalian tissues, this review limits itself to the literature describing the multiple roles of TRP channels in different ocular tissues. Accordingly, their importance to the corneal, trabecular meshwork, lens, ciliary muscle, retinal, microglial and retinal pigment epithelial physiology and pathology is reviewed.

  14. TRP channels in prostate cancer: the good, the bad and the ugly?

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    Gkika, Dimitra; Prevarskaya, Natalia

    2011-01-01

    During the last decade, transient receptor potential (TRP) channels emerge as key proteins in central mechanisms of the carcinogenesis such as cell proliferation, apoptosis and migration. Initial studies showed that expression profile of some TRP channels, notably TRP melastatin 8 (TRPM8), TRP vanilloid 6 (TRPV6),TRP canonical (TRPC6) and TRPV2, is changing during the development and the progression of prostate cancer towards the hormone-refractory stages. The link between the change in expression levels and the functional role of these channels in prostate cancer is step by step being elucidated. These recent advances are here described and discussed. PMID:21623387

  15. Interplay between TRP channels and the cytoskeleton in health and disease.

    NARCIS (Netherlands)

    Clark, K.; Middelbeek, J.; Leeuwen, F.N. van

    2008-01-01

    Transient receptor potential (TRP) channels are a family of cation channels that play a key role in ion homeostasis and cell volume regulation. In addition, TRP channels are considered universal integrators of sensory information required for taste, vision, hearing, touch, temperature, and the

  16. Genetic strategies to analyze primary TRP channel-expressing cells in mice.

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    Wyatt, Amanda; Wartenberg, Philipp; Candlish, Michael; Krasteva-Christ, Gabriela; Flockerzi, Veit; Boehm, Ulrich

    2017-11-01

    Transient receptor potential (TRP) ion channels regulate fundamental biological processes throughout the body. TRP channel dysfunction has been causally linked to a number of disease states and thus establishes these channels as promising therapeutic targets. In order to dissect the physiological role of individual TRP channels in specific tissues, a detailed understanding of the expression pattern of the different TRP channels throughout the organism is essential. We provide an overview of recent efforts to generate novel TRP channel reporter mouse strains for all 28 TRP channels encoded in the mouse genome to understand expression of these channels with a single-cell resolution in an organism-wide manner. The reporter mice will enable both the visualization and manipulation of all primary TRP channel-expressing cells allowing an unprecedented wealth in variety to investigate TRP channel function in vivo. As proof of principle, we provide preliminary results documenting TRPM5 expression throughout the entire body of juvenile and adult mice. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Significance of the Centrally Expressed TRP Channel "Painless" in "Drosophila" Courtship Memory

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    Sakai, Takaomi; Sato, Shoma; Ishimoto, Hiroshi; Kitamoto, Toshihiro

    2013-01-01

    Considerable evidence has demonstrated that transient receptor potential (TRP) channels play vital roles in sensory neurons, mediating responses to various environmental stimuli. In contrast, relatively little is known about how TRP channels exert their effects in the central nervous system to control complex behaviors. This is also true for the…

  18. Nociceptive TRP Channels: Sensory Detectors and Transducers in Multiple Pain Pathologies

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    Aaron D. Mickle

    2016-11-01

    Full Text Available Specialized receptors belonging to the transient receptor potential (TRP family of ligand-gated ion channels constitute the critical detectors and transducers of pain-causing stimuli. Nociceptive TRP channels are predominantly expressed by distinct subsets of sensory neurons of the peripheral nervous system. Several of these TRP channels are also expressed in neurons of the central nervous system, and in non-neuronal cells that communicate with sensory nerves. Nociceptive TRPs are activated by specific physico-chemical stimuli to provide the excitatory trigger in neurons. In addition, decades of research has identified a large number of immune and neuromodulators as mediators of nociceptive TRP channel activation during injury, inflammatory and other pathological conditions. These findings have led to aggressive targeting of TRP channels for the development of new-generation analgesics. This review summarizes the complex activation and/or modulation of nociceptive TRP channels under pathophysiological conditions, and how these changes underlie acute and chronic pain conditions. Furthermore, development of small-molecule antagonists for several TRP channels as analgesics, and the positive and negative outcomes of these drugs in clinical trials are discussed. Understanding the diverse functional and modulatory properties of nociceptive TRP channels is critical to function-based drug targeting for the development of evidence-based and efficacious new generation analgesics.

  19. Beyond ion-conduction: Channel-dependent and -independent roles of TRP channels during development and tissue homeostasis

    NARCIS (Netherlands)

    Vrenken, K.S.; Jalink, K.; Leeuwen, F.N. van; Middelbeek, J.A.

    2016-01-01

    Transient receptor potential (TRP) channels comprise a family of cation channels implicated in a variety of cellular processes, including proliferation, cell migration and cell survival. As a consequence, members of this ion family play prominent roles during embryonic development, tissue

  20. A polycystin-type transient receptor potential (Trp channel that is activated by ATP

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    David Traynor

    2017-02-01

    Full Text Available ATP and ADP are ancient extra-cellular signalling molecules that in Dictyostelium amoebae cause rapid, transient increases in cytosolic calcium due to an influx through the plasma membrane. This response is independent of hetero-trimeric G-proteins, the putative IP3 receptor IplA and all P2X channels. We show, unexpectedly, that it is abolished in mutants of the polycystin-type transient receptor potential channel, TrpP. Responses to the chemoattractants cyclic-AMP and folic acid are unaffected in TrpP mutants. We report that the DIF morphogens, cyclic-di-GMP, GABA, glutamate and adenosine all induce strong cytoplasmic calcium responses, likewise independently of TrpP. Thus, TrpP is dedicated to purinergic signalling. ATP treatment causes cell blebbing within seconds but this does not require TrpP, implicating a separate purinergic receptor. We could detect no effect of ATP on chemotaxis and TrpP mutants grow, chemotax and develop almost normally in standard conditions. No gating ligand is known for the human homologue of TrpP, polycystin-2, which causes polycystic kidney disease. Our results now show that TrpP mediates purinergic signalling in Dictyostelium and is directly or indirectly gated by ATP.

  1. Immunolocalization and distribution of functional temperature-sensitive TRP channels in salivary glands.

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    Sobhan, Ubaidus; Sato, Masaki; Shinomiya, Takashi; Okubo, Migiwa; Tsumura, Maki; Muramatsu, Takashi; Kawaguchi, Mitsuru; Tazaki, Masakazu; Shibukawa, Yoshiyuki

    2013-11-01

    Transient receptor potential (TRP) cation channels are unique cellular sensors involved in multiple cellular functions. Their role in salivary secretion remains to be elucidated. The expression and localization of temperature-sensitive TRP channels in salivary (submandibular, sublingual and parotid) glands were analyzed by immunohistochemistry and quantitative real-time reverse transcription plus the polymerase chain reaction (RT-PCR). The effects of various TRP channel agonists on carbachol (CCh)-induced salivary secretion in the submandibular gland and on the intracellular Ca(2+) concentration ([Ca(2+)]i) in a submandibular epithelial cell line were also investigated. Immunohistochemistry revealed the expression of TRP-melastatin subfamily member 8 (TRPM8) and TRP-ankyrin subfamily member 1 (TRPA1) in myoepithelial, acinar and ductal cells in the sublingual, submandibular and parotid glands. In addition, TRP-vanilloid subfamily member 1 (TRPV1), TRPV3 and TRPV4 were also expressed in myoepithelial, acinar and ductal cells in all three types of gland. Quantitative real-time RT-PCR results demonstrated the mRNA expression of TRPV1, TRPV3, TRPV4, TRPM8 and TRPA1 in acinar and ductal cells in these salivary glands. Perfusion of the entire submandibular gland with the TRPV1 agonist capsaicin (1 μM) via the submandibular artery significantly increased CCh-induced salivation, whereas perfusion with TRPM8 and TRPA1 agonists (0.5 μM WS12 and 100 μM allyl isothiocyanate) decreased it. Application of agonists for each of the thermosensitive TRP channels increased [Ca(2+)]i in a submandibular epithelial cell line. These results indicate that temperature-sensitive TRP channels are localized and distributed in acinar, ductal and myoepithelial cells in salivary glands and that they play a functional role in the regulation and/or modulation of salivary secretion.

  2. Thermo-sensitive TRP channels in peripheral nerve injury: a review of their role in cold intolerance.

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    Kambiz, S; Duraku, L S; Holstege, J C; Hovius, S E R; Ruigrok, T J H; Walbeehm, E T

    2014-05-01

    One of the sensory complications of traumatic peripheral nerve injury is thermal intolerance, which manifests in humans mainly as cold intolerance. It has a major effect on the quality of life, and adequate therapy is not yet available. In order to better understand the pathophysiological background of thermal intolerance, we focus first on the various transient receptor potential (TRP) channels that are involved in temperature sensation, including their presence in peripheral nerves and in keratinocytes. Second, the role of thermo-sensitive TRP channels in cold and heat intolerance is described showing three different mechanisms that contribute to thermal intolerance in the skin: (a) an increased expression of TRP channels on nerve fibres and on keratinocytes, (b) a lower activation threshold of TRP channels and (c) the sprouting of non-injured nerve fibres. Finally, the data that are available on the effects of TRP channel agonists and antagonists and their clinical use are discussed. In conclusion, TRP channels play a major role in temperature sensation and in cold and heat intolerance. Unfortunately, the available pharmaceutical agents that successfully target TRP channels and counteract thermal intolerance are still very limited. Yet, our focus should remain on TRP channels since it is difficult to imagine a reliable treatment for thermal intolerance that will not involve TRP channels. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  3. Natural product modulators of transient receptor potential (TRP) channels as potential anti-cancer agents.

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    Rodrigues, Tiago; Sieglitz, Florian; Bernardes, Gonçalo J L

    2016-11-07

    Treatment of cancer is a significant challenge in clinical medicine, and its research is a top priority in chemical biology and drug discovery. Consequently, there is an urgent need for identifying innovative chemotypes capable of modulating unexploited drug targets. The transient receptor potential (TRPs) channels persist scarcely explored as targets, despite intervening in a plethora of pathophysiological events in numerous diseases, including cancer. Both agonists and antagonists have proven capable of evoking phenotype changes leading to either cell death or reduced cell migration. Among these, natural products entail biologically pre-validated and privileged architectures for TRP recognition. Furthermore, several natural products have significantly contributed to our current knowledge on TRP biology. In this Tutorial Review we focus on selected natural products, e.g. capsaicinoids, cannabinoids and terpenes, by highlighting challenges and opportunities in their use as starting points for designing natural product-inspired TRP channel modulators. Importantly, the de-orphanization of natural products as TRP channel ligands may leverage their exploration as viable strategy for developing anticancer therapies. Finally, we foresee that TRP channels may be explored for the selective pharmacodelivery of cytotoxic payloads to diseased tissues, providing an innovative platform in chemical biology and molecular medicine.

  4. Thermodynamic implications of high Q 10 of thermo-TRP channels in living cells

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    Ito, Etsuro; Ikemoto, Yusuke; Yoshioka, Tohru

    2015-01-01

    The activity of thermo-transient receptor potential (TRP) channels is highly dependent on temperature, and thus thermo-TRP reactions have a high temperature coefficient Q 10. In thermodynamics, a high value of Q 10 indicates the existence of a large activation energy (i.e., a large enthalpy) over a short period during the transition process between the closed and open states of the channels. The Gibbs free energy equation shows that a large entropy is required to compensate for this large ent...

  5. Sensory TRP Channel Interactions with Endogenous Lipids and Their Biological Outcomes

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    Sungjae Yoo

    2014-04-01

    Full Text Available Lipids have long been studied as constituents of the cellular architecture and energy stores in the body. Evidence is now rapidly growing that particular lipid species are also important for molecular and cellular signaling. Here we review the current information on interactions between lipids and transient receptor potential (TRP ion channels in nociceptive sensory afferents that mediate pain signaling. Sensory neuronal TRP channels play a crucial role in the detection of a variety of external and internal changes, particularly with damaging or pain-eliciting potentials that include noxiously high or low temperatures, stretching, and harmful substances. In addition, recent findings suggest that TRPs also contribute to altering synaptic plasticity that deteriorates chronic pain states. In both of these processes, specific lipids are often generated and have been found to strongly modulate TRP activities, resulting primarily in pain exacerbation. This review summarizes three standpoints viewing those lipid functions for TRP modulations as second messengers, intercellular transmitters, or bilayer building blocks. Based on these hypotheses, we discuss perspectives that account for how the TRP-lipid interaction contributes to the peripheral pain mechanism. Still a number of blurred aspects remain to be examined, which will be answered by future efforts and may help to better control pain states.

  6. Transient receptor potential (TRP) channels as drug targets for diseases of the digestive system

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    Holzer, Peter

    2011-01-01

    Approximately 20 of the 30 mammalian transient receptor potential (TRP) channel subunits are expressed by specific neurons and cells within the alimentary canal. They subserve important roles in taste, chemesthesis, mechanosensation, pain and hyperalgesia and contribute to the regulation of gastrointestinal motility, absorptive and secretory processes, blood flow, and mucosal homeostasis. In a cellular perspective, TRP channels operate either as primary detectors of chemical and physical stimuli, as secondary transducers of ionotropic or metabotropic receptors, or as ion transport channels. The polymodal sensory function of TRPA1, TRPM5, TRPM8, TRPP2, TRPV1, TRPV3 and TRPV4 enables the digestive system to survey its physical and chemical environment, which is relevant to all processes of digestion. TRPV5 and TRPV6 as well as TRPM6 and TRPM7 contribute to the absorption of Ca2+ and Mg2+, respectively. TRPM7 participates in intestinal pacemaker activity, and TRPC4 transduces muscarinic acetylcholine receptor activation to smooth muscle contraction. Changes in TRP channel expression or function are associated with a variety of diseases/disorders of the digestive system, notably gastro-esophageal reflux disease, inflammatory bowel disease, pain and hyperalgesia in heartburn, functional dyspepsia and irritable bowel syndrome, cholera, hypomagnesemia with secondary hypocalcemia, infantile hypertrophic pyloric stenosis, esophageal, gastrointestinal and pancreatic cancer, and polycystic liver disease. These implications identify TRP channels as promising drug targets for the management of a number of gastrointestinal pathologies. As a result, major efforts are put into the development of selective TRP channel agonists and antagonists and the assessment of their therapeutic potential. PMID:21420431

  7. TRP, TRPL and cacophony channels mediate Ca2+ influx and exocytosis in photoreceptors axons in Drosophila.

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    Guadalupe Astorga

    Full Text Available In Drosophila photoreceptors Ca(2+-permeable channels TRP and TRPL are the targets of phototransduction, occurring in photosensitive microvilli and mediated by a phospholipase C (PLC pathway. Using a novel Drosophila brain slice preparation, we studied the distribution and physiological properties of TRP and TRPL in the lamina of the visual system. Immunohistochemical images revealed considerable expression in photoreceptors axons at the lamina. Other phototransduction proteins are also present, mainly PLC and protein kinase C, while rhodopsin is absent. The voltage-dependent Ca(2+ channel cacophony is also present there. Measurements in the lamina with the Ca(2+ fluorescent protein G-CaMP ectopically expressed in photoreceptors, revealed depolarization-induced Ca(2+ increments mediated by cacophony. Additional Ca(2+ influx depends on TRP and TRPL, apparently functioning as store-operated channels. Single synaptic boutons resolved in the lamina by FM4-64 fluorescence revealed that vesicle exocytosis depends on cacophony, TRP and TRPL. In the PLC mutant norpA bouton labeling was also impaired, implicating an additional modulation by this enzyme. Internal Ca(2+ also contributes to exocytosis, since this process was reduced after Ca(2+-store depletion. Therefore, several Ca(2+ pathways participate in photoreceptor neurotransmitter release: one is activated by depolarization and involves cacophony; this is complemented by internal Ca(2+ release and the activation of TRP and TRPL coupled to Ca(2+ depletion of internal reservoirs. PLC may regulate the last two processes. TRP and TRPL would participate in two different functions in distant cellular regions, where they are opened by different mechanisms. This work sheds new light on the mechanism of neurotransmitter release in tonic synapses of non-spiking neurons.

  8. Role of the transient receptor potential (TRP) channel gene expressions and TRP melastatin (TRPM) channel gene polymorphisms in obesity-related metabolic syndrome.

    Science.gov (United States)

    Tabur, S; Oztuzcu, S; Duzen, I V; Eraydin, A; Eroglu, S; Ozkaya, M; Demiryürek, A T

    2015-04-01

    Metabolic syndrome (MetS) is correlated with increased cardiovascular risk and characterized by several factors, including visceral obesity, hypertension, dyslipidemia, and insulin resistance. The etiology of MetS is complex, and can be influenced by genetic susceptibility. The aim of this study was to investigate a possible association of transient receptor potential (TRP) channels gene expressions and TRP melastatin (TRPM) gene polymorphisms with MetS in a Turkish population. A total of 142 patients with obesity-related MetS and 166 healthy controls with similar age and sex were enrolled to this study. For polymorphism studies, genomic DNA from the participants was analyzed by a BioMark 96.96 dynamic array system (Fluidigm, South San Francisco, CA, USA). For gene expression studies, mRNA from blood samples was extracted, and real time polymerase chain reaction on the BioMark HD system was performed. There was an increase in A allele (64.6% in patients vs. 49.5% in controls) and decrease in G allele frequencies (35.4% in patients vs. 50.5% in control, p = 0.0019) of the TRPM5 gene rs4929982 (Arg578Gln) polymorphism. We also observed that the distribution of genotype and allele frequencies of the TRPM8 gene rs12472151 in MetS patients were significantly different from controls (p TRPM5, TRPV4, TRPV5, TRPV6, MCOLN2 (TRPML2), and MCOLN3 (TRPML3) gene expressions, an augmentation was noted in TRPC6 gene expression. Genetic polymorphisms in TRPM5 and TRPM8 genes may modify individual susceptibility to MetS in the Turkish population. This study also revealed that there is a significant relationship between TRP channels gene expressions and MetS.

  9. Transient Receptor Potential (TRP Channels in Drug Discovery: Old Concepts & New Thoughts

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    Susan Huang

    2017-07-01

    Full Text Available 2017 marks the 20th anniversary of the molecular cloning by David Julius and colleagues (1997 of the long sought-after capsaicin receptor, now known as TRPV1 (Transient Receptor Potential Vanilloid 1 [1]. This seminal discovery has opened up a “hot” new field of basic research and launched drug discovery efforts into the large family (by the latest count 28 mammalian members, 27 in humans of TRP ion channels [2]. Indeed, it took less than a decade for the first potent, small molecule TRPV1 antagonists to enter phase 1 clinical trials [3]. Yet, despite the large amount of resources that has been invested in TRPV1 research, there are currently no TRPV1-targeted drugs in phase 3 clinical trials. In this special issue of Pharmaceuticals, we aim to capture the progress in the TRP channel field over the past twenty years, with 15 articles covering a variety of TRP channels and potential relevant disease states and applications.

  10. TRP channels as targets for therapeutic intervention in obesity: focus on TRPV1 and TRPM5.

    Science.gov (United States)

    Palmer, R Kyle; Lunn, Charles A

    2013-01-01

    The disease of obesity is one of the greatest healthcare challenges of our time. The increasing urgency for effective treatment is driving an intensive search for new targets for anti-obesity drug discovery. The TRP channel super family represents a class of proteins now recognized to serve many functions in physiology related to maintenance of health and the development of diseases. A few of these might offer new potential for therapeutic intervention in obesity. Among the TRP channels, TRPV1 appears most closely associated with body weight homeostasis through its influence on energy expenditure. TRPM5 has been thoroughly characterized as a critical component of taste signaling and recently has been implicated in insulin release. Because of its role in taste signaling, we argue that drugs designed to modulate TRPM5 could be useful in controlling energy consumption by impacting taste sensory signals. As drug targets for obesity, both TRPV1 and TRPM5 offer the advantage of operating in compartments that could limit drug distribution to the site of action. The potential for other TRP channels as anti-obesity drug targets also is discussed.

  11. Extracts and compounds active on TRP ion channels from Waldheimia glabra, a ritual medicinal plant from Himalaya.

    Science.gov (United States)

    Giorgi, Annamaria; Bassoli, Angela; Borgonovo, Gigliola; Panseri, Sara; Manzo, Alessandra; Pentimalli, Daniela; Schiano Moriello, Aniello; De Petrocellis, Luciano

    2017-08-15

    Waldheimia glabra (Decne.) Regel is a wild plant from the Himalayan Mountains, commonly known as Smooth Ground Daisy. This plant is traditionally used by local populations in religious rituals (incense) or in traditional herbal medicine to treat skin diseases, headache, joint pain and fever. In literature few data are available on the investigation of this aromatic plant. The present work aims at deepening knowledge about the chemical composition of W. glabra extracts and incense, as well as its activity on TRP ion channels. Extracts and incense of W. glabra were analyzed by using HS-SPME GC/MS, GC/MS and NMR analysis. Tests on the activity of W. glabra extracts and isolated compounds (+)-ludartin 1 and B-ring-homo-tonghaosu 2 on TRP channels were also performed. Some extracts and pure compounds from W. glabra showed an interesting activity in terms of efficacy and potency on rat TRPA1, an ion channel involved in several sensory mechanisms, including pungency, environmental irritation and pain perception. Activity is discussed and compared with that of other known TRPA1 natural agonists with different chemical structures. All compounds showed only a negligible inhibition activity on rat TRPM8 ion channel. Our findings demonstrate that W. glabra is involved in the receptor activation mechanism and therefore represents a new natural product potentially useful in pharmaceutical and agrifood research. Copyright © 2017 Elsevier GmbH. All rights reserved.

  12. Expression and distribution of transient receptor potential (TRP) channels in bladder epithelium.

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    Yu, Weiqun; Hill, Warren G; Apodaca, Gerard; Zeidel, Mark L

    2011-01-01

    The urothelium is proposed to be a sensory tissue that responds to mechanical stress by undergoing dynamic membrane trafficking and neurotransmitter release; however, the molecular basis of this function is poorly understood. Transient receptor potential (TRP) channels are ideal candidates to fulfill such a role as they can sense changes in temperature, osmolarity, and mechanical stimuli, and several are reported to be expressed in the bladder epithelium. However, their complete expression profile is unknown and their cellular localization is largely undefined. We analyzed expression of all 33 TRP family members in mouse bladder and urothelium by RT-PCR and found 22 specifically expressed in the urothelium. Of the latter, 10 were chosen for closer investigation based on their known mechanosensory or membrane trafficking functions in other cell types. Western blots confirmed urothelial expression of TRPC1, TRPC4, TRPV1, TRPV2, TRPV4, TRPM4, TRPM7, TRPML1, and polycystins 1 and 2 (PKD1 and PKD2) proteins. We further defined the cellular and subcellular localization of all 10 TRP channels. TRPV2 and TRPM4 were prominently localized to the umbrella cell apical membrane, while TRPC4 and TRPV4 were identified on their abluminal surfaces. TRPC1, TRPM7, and TRPML1 were localized to the cytoplasm, while PKD1 and PKD2 were expressed on the apical and basolateral membranes of umbrella cells as well as in the cytoplasm. The cellular location of TRPV1 in the bladder has been debated, but colocalization with neuronal marker calcitonin gene-related peptide indicated clearly that it is present on afferent neurons that extend into the urothelium, but may not be expressed by the urothelium itself. These findings are consistent with the hypothesis that the urothelium acts as a sentinel and by expressing multiple TRP channels it is likely it can detect and presumably respond to a diversity of external stimuli and suggest that it plays an important role in urothelial signal

  13. The core domain as the force sensor of the yeast mechanosensitive TRP channel.

    Science.gov (United States)

    Su, Zhenwei; Anishkin, Andriy; Kung, Ching; Saimi, Yoshiro

    2011-12-01

    Stretch-activated conductances are commonly encountered in careful electric recordings. Those of known proteins (TRP, MscL, MscS, K(2p), Kv, etc.) all share a core, which houses the ion pathway and the gate, but no recognizable force-sensing domain. Like animal TRPs, the yeast TRPY1 is polymodal, activated by stretch force, Ca(2+), etc. To test whether its S5-S6 core senses the stretch force, we tried to uncouple it from the peripheral domains by strategic peptide insertions to block the covalent core-periphery interactions. Insertion of long unstructured peptides should distort, if not disrupt, protein structures that transmit force. Such insertions between S6 and the C-terminal tail largely removed Ca(2+) activation, showing their effectiveness. However, such insertions as well as those between S5 and the N-terminal region, which includes S1-S4, did not significantly alter mechanosensitivity. Even insertions at both locations flanking the S5-S6 core did not much alter mechanosensitivity. Tryptophan scanning mutations in S5 were also constructed to perturb possible noncovalent core-periphery contacts. The testable tryptophan mutations also have little or no effects on mechanosensitivity. Boltzmann fits of the wild-type force-response curves agree with a structural homology model for a stretch-induced core expansion of ~2 nm(2) upon opening. We hypothesize that membrane tension pulls on S5-S6, expanding the core and opening the TRPY1 gate. The core being the major force sensor offers the simplest, though not the only, explanation of why so many channels of disparate designs are mechanically sensitive. Compared with the bacterial MscL, TRPY1 is much less sensitive to force, befitting a polymodal channel that relies on multiple stimuli.

  14. Functional TRP and ASIC-like channels in cultured urothelial cells from the rat.

    Science.gov (United States)

    Kullmann, F Aura; Shah, M A; Birder, L A; de Groat, W C

    2009-04-01

    Transient receptor potential (TRP) and acid-sensing ion channels (ASIC) are molecular detectors of chemical, mechanical, thermal, and nociceptive stimuli in sensory neurons. They have been identified in the urothelium, a tissue considered part of bladder sensory pathways, where they might play a role in bladder function. This study investigated functional properties of TRP and ASIC channels in cultured urothelial cells from the rat using patch-clamp and fura 2 Ca(2+) imaging techniques. The TRPV4 agonist 4alpha-phorbol-12,13 didecanoate (4alpha-PDD; 1-5 microM) and the TRPA1/TRPM8 agonist icilin (50-100 microM) elicited transient currents in a high percentage of cells (>70%). 4alpha-PDD responses were suppressed by the TRPV4 antagonist HC-010961 (10 microM). The TRPV1 agonist capsaicin (1-100 microM) and the TRPA1/TRPM8 agonist menthol (5-200 microM) elicited transient currents in a moderate percentage of cells ( approximately 25%). All of these agonists increased intracellular calcium concentration ([Ca(2+)](i)). Most cells responded to more than one TRP agonist (e.g., capsaicin and 4alpha-PDD), indicating coexpression of different TRP channels. In the presence of the TRPV1 antagonist capsazepine (10 microM), changes in pH induced by HCl elicited ionic currents (pH 5.5) and increased [Ca(2+)](i) (pH 6.5) in approximately 50% of cells. Changes in pH using acetic acid (pH 5.5) elicited biphasic-like currents. Responses induced by acid were sensitive to amiloride (10 microM). In summary, urothelial cells express multiple TRP and ASIC channels, whose activation elicits ionic currents and Ca(2+) influx. These "neuron-like" properties might be involved in transmitter release, such as ATP, that can act on afferent nerves or smooth muscle to modulate their responses to different stimuli.

  15. TRP channels and traffic-related environmental pollution-induced pulmonary disease.

    Science.gov (United States)

    Akopian, Armen N; Fanick, E Robert; Brooks, Edward G

    2016-05-01

    Environmental pollutant exposures are major risk factors for adverse health outcomes, with increased morbidity and mortality in humans. Diesel exhaust (DE) is one of the major harmful components of traffic-related air pollution. Exposure to DE affects several physiological systems, including the airways, and pulmonary diseases are increased in highly populated urban areas. Hence, there are urgent needs to (1) create newer and lesser polluting fuels, (2) improve exhaust aftertreatments and reduce emissions, and (3) understand mechanisms of actions for toxic effects of both conventional and cleaner diesel fuels on the lungs. These steps could aid the development of diagnostics and interventions to prevent the negative impact of traffic-related air pollution on the pulmonary system. Exhaust from conventional, and to a lesser extent, clean fuels, contains particulate matter (PM) and more than 400 additional chemical constituents. The major toxic constituents are nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons (PAHs). PM and PAHs could potentially act via transient receptor potential (TRP) channels. In this review, we will first discuss the associations between DE from conventional as well as clean fuel technologies and acute and chronic airway inflammation. We will then review possible activation and/or potentiation of TRP vanilloid type 1 (TRPV1) and ankyrin 1 (TRPA1) channels by PM and PAHs. Finally, we will discuss and summarize recent findings on the mechanisms whereby TRPs could control the link between DE and airway inflammation, which is a primary determinant leading to pulmonary disease.

  16. A TRP Channel Senses Lysosome Neutralization by Pathogens to Trigger Their Expulsion

    Science.gov (United States)

    Miao, Yuxuan; Li, Guojie; Zhang, Xiaoli; Xu, Haoxing; Abraham, Soman N.

    2015-01-01

    SUMMARY Vertebrate cells have evolved elaborate cell-autonomous defense programs to monitor subcellular compartments for infection and to evoke counter-responses. These programs are activated by pathogen-associated pattern molecules and by various strategies intracellular pathogens employ to alter cellular microenvironments. Here, we show that when uropathogenic E. coli (UPEC) infect bladder epithelial cells (BECs), they are targeted by autophagy but avoid degradation because of their capacity to neutralize lysosomal pH. This change is detected by mucolipin TRP channel 3 (TRPML3), a transient receptor potential cation channel localized to lysosomes. TRPML3 activation then spontaneously initiates lysosome exocytosis, resulting in expulsion of exosome-encased bacteria. These studies reveal a cellular default system for lysosome homeostasis that has been co-opted by the autonomous defense program to clear recalcitrant pathogens. PMID:26027738

  17. Endocannabinoids as regulators of transient receptor potential (TRP) channels: A further opportunity to develop new endocannabinoid-based therapeutic drugs.

    Science.gov (United States)

    Di Marzo, V; De Petrocellis, L

    2010-01-01

    In the late 1990's, a series of experiments carried out independently in two laboratories led to establish an important connection between the function of the endocannabinoids, which, as exemplified in this special issue, is per se very complex and ubiquitous in animals, and that of the transient receptor potential (TRP) channels, a large family of plasma membrane cation channels involved in several mammalian and non-mammalian physiological and pathological conditions, overlapping only in part with those in which the cannabinoid receptors participate. These experiments were initially based on the observation that the endocannabinoid anandamide and the xenobiotic ligand of TRP channels of V1 type (TRPV1), capsaicin, are somehow chemically similar, both compounds being fatty acid amides, as are also synthetic activators of these channels and inhibitors of anandamide cellular re-uptake. As discussed in this article, the same type of "chemical thoughts" led to the discovery of N-arachidonoyl-dopamine, an endogenous ligand of TRPV1 channels that behaves also an endocannabinoid. The overlap between the ligand recognition properties of some TRP channels and proteins of the endocannabinoid system, namely the cannabinoid receptors and the proteins and enzymes catalyzing anandamide cellular re-uptake and hydrolysis, is being actively explored through the rational design and synthesis of new endocannabinoid-based drugs with multiple mechanisms of action. These aspects are discussed in this review article, together with the possible functional and pharmacological consequences of endocannabinoid-TRP channel interactions.

  18. Pre-clinical studies in cough research: Role of Transient Receptor Potential (TRP) channels

    Science.gov (United States)

    Grace, Megan S.; Dubuis, Eric; Birrell, Mark A.; Belvisi, Maria G.

    2013-01-01

    Cough is a protective reflex and defence mechanism in healthy individuals, which helps clear excessive secretions and foreign material from the lungs. Cough often presents as the first and most persistent symptom of many respiratory diseases and some non-respiratory disorders, but can also be idiopathic, and is a common respiratory complaint for which medical attention is sought. Chronic cough of various aetiologies is a regular presentation to specialist respiratory clinics, and is reported as a troublesome symptom by a significant proportion of the population. Despite this, the treatment options for cough are limited. The lack of effective anti-tussives likely stems from our incomplete understanding of how the tussive reflex is mediated. However, research over the last decade has begun to shed some light on the mechanisms which provoke cough, and may ultimately provide us with better anti-tussive therapies. This review will focus on the in vitro and in vivo models that are currently used to further our understanding of the sensory innervation of the respiratory tract, and how these nerves are involved in controlling the cough response. Central to this are the Transient Receptor Potential (TRP) ion channels, a family of polymodal receptors that can be activated by such diverse stimuli as chemicals, temperature, osmotic stress, and mechanical perturbation. These ion channels are thought to be molecular pain integrators and targets for novel analgesic agents for the treatment of various pain disorders but some are also being developed as anti-tussives. PMID:23474212

  19. Systematic and quantitative mRNA expression analysis of TRP channel genes at the single trigeminal and dorsal root ganglion level in mouse

    Directory of Open Access Journals (Sweden)

    Vandewauw Ine

    2013-02-01

    Full Text Available Abstract Background Somatosensory nerve fibres arising from cell bodies within the trigeminal ganglia (TG in the head and from a string of dorsal root ganglia (DRG located lateral to the spinal cord convey endogenous and environmental stimuli to the central nervous system. Although several members of the transient receptor potential (TRP superfamily of cation channels have been implicated in somatosensation, the expression levels of TRP channel genes in the individual sensory ganglia have never been systematically studied. Results Here, we used quantitative real-time PCR to analyse and compare mRNA expression of all TRP channels in TG and individual DRGs from 27 anatomically defined segments of the spinal cord of the mouse. At the mRNA level, 17 of the 28 TRP channel genes, TRPA1, TRPC1, TRPC3, TRPC4, TRPC5, TRPM2, TRPM3, TRPM4, TRPM5, TRPM6, TRPM7, TRPM8, TRPV1, TRPV2, TRPV4, TRPML1 and TRPP2, were detectable in every tested ganglion. Notably, four TRP channels, TRPC4, TRPM4, TRPM8 and TRPV1, showed statistically significant variation in mRNA levels between DRGs from different segments, suggesting ganglion-specific regulation of TRP channel gene expression. These ganglion-to-ganglion differences in TRP channel transcript levels may contribute to the variability in sensory responses in functional studies. Conclusions We developed, compared and refined techniques to quantitatively analyse the relative mRNA expression of all TRP channel genes at the single ganglion level. This study also provides for the first time a comparative mRNA distribution profile in TG and DRG along the entire vertebral column for the mammalian TRP channel family.

  20. Effects of cannabinoids and cannabinoid-enriched Cannabis extracts on TRP channels and endocannabinoid metabolic enzymes.

    Science.gov (United States)

    De Petrocellis, Luciano; Ligresti, Alessia; Moriello, Aniello Schiano; Allarà, Marco; Bisogno, Tiziana; Petrosino, Stefania; Stott, Colin G; Di Marzo, Vincenzo

    2011-08-01

    Cannabidiol (CBD) and Δ(9) -tetrahydrocannabinol (THC) interact with transient receptor potential (TRP) channels and enzymes of the endocannabinoid system. The effects of 11 pure cannabinoids and botanical extracts [botanical drug substance (BDS)] from Cannabis varieties selected to contain a more abundant cannabinoid, on TRPV1, TRPV2, TRPM8, TRPA1, human recombinant diacylglycerol lipase α (DAGLα), rat brain fatty acid amide hydrolase (FAAH), COS cell monoacylglycerol lipase (MAGL), human recombinant N-acylethanolamine acid amide hydrolase (NAAA) and anandamide cellular uptake (ACU) by RBL-2H3 cells, were studied using fluorescence-based calcium assays in transfected cells and radiolabelled substrate-based enzymatic assays. Cannabinol (CBN), cannabichromene (CBC), the acids (CBDA, CBGA, THCA) and propyl homologues (CBDV, CBGV, THCV) of CBD, cannabigerol (CBG) and THC, and tetrahydrocannabivarin acid (THCVA) were also tested. CBD, CBG, CBGV and THCV stimulated and desensitized human TRPV1. CBC, CBD and CBN were potent rat TRPA1 agonists and desensitizers, but THCV-BDS was the most potent compound at this target. CBG-BDS and THCV-BDS were the most potent rat TRPM8 antagonists. All non-acid cannabinoids, except CBC and CBN, potently activated and desensitized rat TRPV2. CBDV and all the acids inhibited DAGLα. Some BDS, but not the pure compounds, inhibited MAGL. CBD was the only compound to inhibit FAAH, whereas the BDS of CBC > CBG > CBGV inhibited NAAA. CBC = CBG > CBD inhibited ACU, as did the BDS of THCVA, CBGV, CBDA and THCA, but the latter extracts were more potent inhibitors. These results are relevant to the analgesic, anti-inflammatory and anti-cancer effects of cannabinoids and Cannabis extracts. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  1. TRP and ASIC channels mediate the antinociceptive effect of citronellyl acetate.

    Science.gov (United States)

    Rios, Emiliano Ricardo Vasconcelos; Rocha, Nayrton Flávio Moura; Carvalho, Alyne Mara Rodrigues; Vasconcelos, Leonardo Freire; Dias, Marília Leite; de Sousa, Damião Pergentino; de Sousa, Francisca Cléa Florenço; Fonteles, Marta Maria de França

    2013-05-25

    Citronellyl acetate (CAT), a monoterpene product of the secondary metabolism of plants, has been shown in the literature to possess several different biological activities. However, no antinociceptive abilities have yet been discussed. Here, we used acute pain animal models to describe the antinociceptive action of CAT. The acetic acid-induced writhing test and the paw-licking test, in which paw licking was induced by glutamate and formalin, were performed to evaluate the antinociceptive action of CAT and to determine the involvement of PKC, PKA, TRPV1, TRPA1, TRPM8 and ASIC in its antinociceptive mechanism. To do so, we induced paw-linking using agonists. CAT was administered intragastrically (25, 50, 75, 100 and 200 mg/kg), and the two higher doses caused antinociceptive effects in the acetic acid model; the highest dose reduced pain for 4h after it was administered (200 mg/kg). In the formalin test, two doses of CAT promoted antinociception in both the early and later phases of the test. The glutamate test showed that its receptors are involved in the antinociceptive mechanism of CAT. Pretreatment with CAT did not alter locomotor activity or motor coordination. In an investigation into the participation of TRP channels and ASICs in CAT's antinociceptive mechanism, we used capsaicin (2.2 μg/paw), cinnamaldehyde (10 mmol/paw), menthol (1.2 mmol/paw) and acidified saline (2% acetic acid, pH 1.98). The results showed that TRPV1, TRPM8 and ASIC, but not TRPA1, are involved in the antinociceptive mechanism. Finally, the involvement of PKC and PKA was also studied, and we showed that both play a role in the antinociceptive mechanism of CAT. The results of this work contribute information regarding the antinociceptive properties of CAT on acute pain and show that, at least in part, TRPV1, TRPM8, ASIC, glutamate receptors, PKC and PKA participate in CAT's antinociceptive mechanism. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. Phytochemicals from Ruta graveolens Activate TAS2R Bitter Taste Receptors and TRP Channels Involved in Gustation and Nociception.

    Science.gov (United States)

    Mancuso, Giuseppe; Borgonovo, Gigliola; Scaglioni, Leonardo; Bassoli, Angela

    2015-10-16

    Ruta graveolens (rue) is a spontaneous plant in the Mediterranean area with a strong aroma and a very intense bitter taste, used in gastronomy and in folk medicine. From the leaves, stems and fruits of rue, we isolated rutin, rutamarin, three furanocoumarins, two quinolinic alkaloids, a dicoumarin and two long chain ketones. Bitter taste and chemesthetic properties have been evaluated by in vitro assays with twenty receptors of the TAS2R family and four TRP ion channels involved in gustation and nociception. Among the alkaloids, skimmianine was active as a specific agonist of T2R14, whereas kokusaginin did not activate any of the tested receptors. The furanocoumarins activates TAS2R10, 14, and 49 with different degrees of selectivity, as well as the TRPA1 somatosensory ion channel. Rutamarin is an agonist of TRPM5 and TRPV1 and a strong antagonist of TRPM8 ion channels.

  3. Phytochemicals from Ruta graveolens Activate TAS2R Bitter Taste Receptors and TRP Channels Involved in Gustation and Nociception

    Directory of Open Access Journals (Sweden)

    Giuseppe Mancuso

    2015-10-01

    Full Text Available Ruta graveolens (rue is a spontaneous plant in the Mediterranean area with a strong aroma and a very intense bitter taste, used in gastronomy and in folk medicine. From the leaves, stems and fruits of rue, we isolated rutin, rutamarin, three furanocoumarins, two quinolinic alkaloids, a dicoumarin and two long chain ketones. Bitter taste and chemesthetic properties have been evaluated by in vitro assays with twenty receptors of the TAS2R family and four TRP ion channels involved in gustation and nociception. Among the alkaloids, skimmianine was active as a specific agonist of T2R14, whereas kokusaginin did not activate any of the tested receptors. The furanocoumarins activates TAS2R10, 14, and 49 with different degrees of selectivity, as well as the TRPA1 somatosensory ion channel. Rutamarin is an agonist of TRPM5 and TRPV1 and a strong antagonist of TRPM8 ion channels.

  4. Structure-activity relationship of Trp-containing analogs of the antimicrobial peptide gomesin.

    Science.gov (United States)

    Domingues, Tatiana M; Buri, Marcus V; Daffre, Sirlei; Campana, Patricia T; Riske, Karin A; Miranda, Antonio

    2014-06-01

    Gomesin (Gm) has a broad antimicrobial activity making it of great interest for development of drugs. In this study, we analyzed three Gm analogs, [Trp(1) ]-Gm, [Trp(7) ]-Gm, and [Trp(9) ]-Gm, in an attempt to gain insight into the contributions of different regions of the peptide sequence to its activity. The incorporation of the tryptophan residue in different positions has no effect on the antimicrobial and hemolytic activities of the Gm analogs in relation to Gm. Spectroscopic studies (circular dichroism, fluorescence and absorbance) of Gm and its analogs were performed in the presence of SDS, below and above its critical micelle concentration (CMC) (~8 mM), in order to monitor structural changes induced by the interaction with this anionic surfactant (0-15 mM). Interestingly, we found that the analogs interact more strongly with SDS at low concentrations (0.3-6.0 mM) than close to or above its CMC. This suggests that SDS monomers are able to cover the whole peptide, forming large detergent-peptide aggregates. On the other hand, the peptides interact differently with SDS micelles, inserting partially into the micelle core. Among the peptides, Trp in position 1 becomes more motionally-restricted in the presence of SDS, probably because this residue is located at the N-terminal region, which presents higher conformational freedom to interact stronger with SDS molecules. Trp residues in positions 7 and 9, close to and in the region of the turn of the molecule, respectively, induced a more constrained structure and the compounds cannot insert deeper into the micelle core or be completely buried by SDS monomers. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.

  5. Transient Receptor Potential channels: What's happening? Reflections in the wake of the 2009 TRP Meeting, Karolinska Institutet, Stockholm.

    Science.gov (United States)

    Goswami, Chandan; Islam, Md Shahidul

    2010-01-01

    More than 150 participants from 25 countries gathered in Stockholm during 25(th) to 27(th) Sept 2009 to attend the meeting "TRP channels: from sensory signaling to human disease" and enjoyed an international, intensive and vibrant meeting. This meeting shed lights on the recent advances made in this field of research in different sectors of biology, and identified directions for future research and the areas where TRP channels could be used as potential targets for prevention and treatment of human diseases. The participants of this meeting shared their recent largely unpublished data, state-of-the-art techniques and their critical views which would push research in this field forward in the new decade. Another major outcome of this meeting was the realization that extensive work remains to be done to develop the necessary tools and enhance the quality of research in this area so that the prevailing controversies can be resolved. In this report we summarize the latest scientific excitements, some critical issues, as well as some future directions for research that were addressed and discussed in this meeting.

  6. A direct comparison of protein structure in the gas and solution phase: the Trp-cage

    DEFF Research Database (Denmark)

    Patriksson, Alexandra; Adams, Christopher M; Kjeldsen, Frank

    2007-01-01

    Molecular dynamics simulations of zwitterions of the Trp-cage protein in the gas phase show that the most stable ion in vacuo has preserved the charge locations acquired in solution. A direct comparison of the gas and solution-phase structures reveals that, despite the similarity in charge location......, there is significant difference in the structures, with a substantial increase in hydrogen bonds and exposure of hydrophobic parts in the gas phase. The structure of the salt bridge in the gas phase is also much more stable than in the (experimental) solution structure....

  7. Sound response mediated by the TRP channels NOMPC, NANCHUNG, and INACTIVE in chordotonal organs of Drosophila larvae.

    Science.gov (United States)

    Zhang, Wei; Yan, Zhiqiang; Jan, Lily Yeh; Jan, Yuh Nung

    2013-08-13

    Mechanical stimuli, including tactile and sound signals, convey a variety of information important for animals to navigate the environment and avoid predators. Recent studies have revealed that Drosophila larvae can sense harsh or gentle touch with dendritic arborization (da) neurons in the body wall and can detect vibration with chordotonal organs (Cho). Whether they can also detect and respond to vibration or sound from their predators remains an open question. Here we report that larvae respond to sound of wasps and yellow jackets, as well as to pure tones of frequencies that are represented in such natural sounds, with startle and burrowing behaviors. The larval response to sound/vibration requires Cho neurons and, to a lesser extent, class IV da neurons. Our calcium imaging and electrophysiological experiments reveal that Cho neurons, but not class IV da neurons, are excited by natural sounds or pure tones, with tuning curves and intensity dependence appropriate for the behavioral responses. Furthermore, our study implicates the transient receptor potential (TRP) channels NOMPC, NANCHUNG, and INACTIVE, but not the dmPIEZO channel, in the mechanotransduction and/or signal amplification for the detection of sound by the larval Cho neurons. These findings indicate that larval Cho, like their counterparts in the adult fly, use some of the same mechanotransduction channels to detect sound waves and mediate the sensation akin to hearing in Drosophila larvae, allowing them to respond to the appearance of predators or other environmental cues at a distance with behaviors crucial for survival.

  8. Broad-range TRP channel inhibitors (2-APB, flufenamic acid, SKF-96365) affect differently contraction of resistance and conduit femoral arteries of rat

    Czech Academy of Sciences Publication Activity Database

    Bencze, Michal; Behuliak, Michal; Vavřínová, Anna; Zicha, Josef

    2015-01-01

    Roč. 765, Oct 15 (2015), s. 533-540 ISSN 0014-2999 R&D Projects: GA ČR(CZ) GAP304/12/0259 Institutional support: RVO:67985823 Keywords : femoral artery * TRP channel * 2-APB * flufenamic acid * SKF-96365 * vascular contraction Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 2.730, year: 2015

  9. A TRP channel contributes to insulin secretion by pancreatic β-cells.

    Science.gov (United States)

    Liman, Emily R

    2010-01-01

    The release of insulin by pancreatic beta cells involves a complex interplay of conductances that generate oscillations and drive secretion. A recent report identifies a new player in this process, the ion channel TRPM5. TRPM5 was originally identified in taste cells, where it forms a Ca(2+)-activated cation channel that is required for sensory responses to bitter and sweet tastes. New research now shows that TRPM5 is expressed within the pancreatic islets of Langerhans, where it regulates the frequency of Ca(2+) oscillations and contributes to insulin release by β-cells.

  10. Nociceptors Boost the Resolution of Fungal Osteoinflammation via the TRP Channel-CGRP-Jdp2 Axis

    Directory of Open Access Journals (Sweden)

    Kenta Maruyama

    2017-06-01

    Full Text Available Candida albicans can enter skeletal tissue through a skin wound in an immunocompromised host or by contamination during orthopedic surgery. Such Candida osteomyelitis is accompanied by severe pain and bone destruction. It is established that nociceptor innervation occurs in skin and bone, but the mechanisms of nociceptive modulation in fungal inflammation remain unclear. In this study, we show that C. albicans stimulates Nav1.8-positive nociceptors via the β-glucan receptor Dectin-1 to induce calcitonin gene-related peptide (CGRP. This induction of CGRP is independent of Bcl-10 or Malt-1 but dependent on transient receptor potential cation channel subfamily V member 1 (TRPV1/transient receptor potential cation channel subfamily A member 1 (TRPA1 ion channels. Hindpaw β-glucan injection after Nav1.8-positive nociceptor ablation or in TRPV1/TRPA1 deficiency showed dramatically increased osteoinflammation accompanied by impaired CGRP production. Strikingly, CGRP suppressed β-glucan-induced inflammation and osteoclast multinucleation via direct suppression of nuclear factor-κB (NF-κB p65 by the transcriptional repressor Jdp2 and inhibition of actin polymerization, respectively. These findings clearly suggest a role for Dectin-1-mediated sensocrine pathways in the resolution of fungal osteoinflammation.

  11. TRP channel blamed for burning cold after a tropical fish meal

    Science.gov (United States)

    Voets, Thomas

    2012-01-01

    EMBO J (2012) 31 19, 3795–3808 doi:10.1038/emboj.2012.207; published online 07312012 Ciguatera is one of the most common forms of food poisoning, occurring after consumption of fish contaminated with ciguatoxins. New work by Vetter et al (2012) reveals the key molecular players that underlie the altered temperature sensation associated with ciguatera. In particular, they show that ciguatoxins act on sensory neurons that express TRPA1, an ion channel implicated in the detection of noxious cold. PMID:22960637

  12. Making sense with TRP channels: store-operated calcium entry and the ion channel Trpm5 in taste receptor cells.

    Science.gov (United States)

    Pérez, Cristian A; Margolskee, Robert F; Kinnamon, Sue C; Ogura, Tatsuya

    2003-01-01

    The sense of taste plays a critical role in the life and nutritional status of organisms. During the last decade, several molecules involved in taste detection and transduction have been identified, providing a better understanding of the molecular physiology of taste receptor cells. However, a comprehensive catalogue of the taste receptor cell signaling machinery is still unavailable. We have recently described the occurrence of calcium signaling mechanisms in taste receptor cells via apparent store-operated channels and identified Trpm5, a novel candidate taste transduction element belonging to the mammalian family of transient receptor potential channels. Trpm5 is expressed in a tissue-restricted manner, with high levels in gustatory tissue. In taste cells, Trpm5 is co-expressed with taste-signaling molecules such as alpha-gustducin, Ggamma(13), phospholipase C beta(2) and inositol 1,4,5-trisphosphate receptor type III. Biophysical studies of Trpm5 heterologously expressed in Xenopus oocytes and mammalian CHO-K1 cells indicate that it functions as a store-operated channel that mediates capacitative calcium entry. The role of store-operated channels and Trpm5 in capacitative calcium entry in taste receptor cells in response to bitter compounds is discussed.

  13. Chemosensory TRP channels in the respiratory tract: role in toxic lung injury and potential as "sweet spots" for targeted therapies.

    Science.gov (United States)

    Büch, Thomas; Schäfer, Eva; Steinritz, Dirk; Dietrich, Alexander; Gudermann, Thomas

    2013-01-01

    Acute toxic lung injury by reactive inhalational compounds is an important and still unresolved medical problem. Hazardous gases or vapors, e. g. chlorine, phosgene, sulfur mustard or methyl isocyanate, are released during occupational accidents or combustion processes and also represent a potential threat in terroristic scenarios. According to their broad-range chemical reactivity, the mechanism of lung injury evoked by these agents has long been described as rather unspecific. Consequently, therapeutic options are still restricted to symptomatic treatment. However, in recent years, ion channels of the transient receptor potential (TRP) family have been identified to act as specific sensor molecules expressed in the respiratory tract and to engage defined signaling pathways upon inhalational exposure to toxic challenges. These pulmonary receptor molecules have been primarily characterized in sensory neurons of the lung. However, chemosensory molecules are also expressed in non-neuronal cells, e.g. in the lung epithelium as well as in the pulmonary vasculature. Thus, activation of respiratory chemosensors by toxic inhalants promotes a complex signaling network directly or indirectly regulating pulmonary blood flow, the integrity of the epithelial lining, and the mucociliary clearance of the bronchial system. This review gives a synopsis on reactive lung-toxic agents and their specific target molecules in the lung and summarizes the current knowledge about the pathophysiological role of chemosensory signaling in neuronal and non-neuronal cells in toxic lung injury. Finally, we describe possible future strategies for a causal, specifically tailored treatment option based on the mechanistic understanding of molecular events ensuing inhalation of lung-toxic agents.

  14. Highlights for the 6th International Ion Channel Conference: ion channel structure, function, disease and therapeutics

    Directory of Open Access Journals (Sweden)

    Limei Wang

    2017-11-01

    Full Text Available To foster communication and interactions amongst international scholars and scientists in the field of ion channel research, the 6th International Ion Channel Conference (IICC-2017 was held between June 23–27, 2017 in the eastern coastal city of Qingdao, China. The meeting consisted of 450 attendees and 130 speakers and poster presenters. The program consisted of research progress, new findings and ongoing studies that were focused on (1 Ion channel structure and function; (2 Ion channel physiology and human diseases; (3 Ion channels as targets for drug discovery; (4 Technological advances in ion channel research. An insightful overview was presented on the structure and function of the mechanotransduction channel Drosophila NOMPC (No mechanoreceptor potential C, a member of the transient receptor potential (TRP channel family. Recent studies on Transmembrane protein 16 or Anoctamin-1 (TMEM16A, a member of the calcium-activated chloride channel [CaCC] family were summarized as well. In addition, topics for ion channel regulation, homeostatic feedback and brain disorders were thoroughly discussed. The presentations at the IICC-2017 offer new insights into our understanding of ion channel structures and functions, and ion channels as targets for drug discovery.

  15. Influence of the ionic liquid [C4mpy][Tf2N] on the structure of the miniprotein Trp-cage.

    Science.gov (United States)

    Baker, Joseph L; Furbish, Jeffrey; Lindberg, Gerrick E

    2015-11-01

    We examine the effect of the ionic liquid [C4mpy][Tf2N] on the structure of the miniprotein Trp-cage and contrast these results with the behavior of Trp-cage in water. We find the ionic liquid has a dramatic effect on Trp-cage, though many similarities with aqueous Trp-cage are observed. We assess Trp-cage folding by monitoring root mean square deviation from the crystallographic structure, radius of gyration, proline cis/trans isomerization state, protein secondary structure, amino acid contact formation and distance, and native and non-native contact formation. Starting from an unfolded configuration, Trp-cage folds in water at 298 K in less than 500 ns of simulation, but has very little mobility in the ionic liquid at the same temperature, which can be ascribed to the higher ionic liquid viscosity. At 365 K, the mobility of the ionic liquid is increased and initial stages of Trp-cage folding are observed, however Trp-cage does not reach the native folded state in 2 μs of simulation in the ionic liquid. Therefore, in addition to conventional molecular dynamics, we also employ scaled molecular dynamics to expedite sampling, and we demonstrate that Trp-cage in the ionic liquid does closely approach the aqueous folded state. Interestingly, while the reduced mobility of the ionic liquid is found to restrict Trp-cage motion, the ionic liquid does facilitate proline cis/trans isomerization events that are not seen in our aqueous simulations. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Opportunistic activation of TRP receptors by endogenous lipids: exploiting lipidomics to understand TRP receptor cellular communication.

    Science.gov (United States)

    Bradshaw, Heather B; Raboune, Siham; Hollis, Jennifer L

    2013-03-19

    Transient receptor potential channels (TRPs) form a large family of ubiquitous non-selective cation channels that function as cellular sensors and in many cases regulate intracellular calcium. Identification of the endogenous ligands that activate these TRP receptors is still under intense investigation with the majority of these channels still remaining "orphans." That these channels respond to a variety of external stimuli (e.g. plant-derived lipids, changes in temperature, and changes in pH) provides a framework for their abilities as cellular sensors, however, the mechanism of direct activation is still under much debate and research. In the cases where endogenous ligands (predominately lipids) have shown direct activation of a channel, multiple ligands have been shown to activate the same channel suggesting that these receptors are "promiscuous" in nature. Lipidomics of a growing class of endogenous lipids, N-acyl amides, the most famous of which is N-arachidonoyl ethanolamine (the endogenous cannabinoid, Anandamide) is providing a novel set of ligands that have been shown to activate some members of the TRP family and have the potential to deorphanize many more. Here it is argued that activation of TRPV receptors, a subset of the larger family of TRPs, by multiple endogenous lipids that are structurally analogous is a model system to drive our understanding that many TRP receptors are not promiscuous, but are more characteristically "opportunistic" in nature; exploiting the structural similarity and biosynthesis of a narrow range of analogous endogenous lipids. In addition, this manuscript will compare the activation properties of TRPC5 to the activity profile of an "orphan" lipid, N-palmitoyl glycine; further demonstrating that lipidomics aimed at expanding our knowledge of the family of N-acyl amides has the potential to provide novel avenues of research for TRP receptors. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. ADP-Induced Ca2+Signaling and Proliferation of Rat Ventricular Myofibroblasts Depend on Phospholipase C-Linked TRP Channels Activation Within Lipid Rafts.

    Science.gov (United States)

    Certal, Mariana; Vinhas, Adriana; Barros-Barbosa, Aurora; Ferreirinha, Fátima; Costa, Maria Adelina; Correia-de-Sá, Paulo

    2017-06-01

    Nucleotides released during heart injury affect myocardium electrophysiology and remodeling through P2 purinoceptors activation in cardiac myofibroblasts. ATP and UTP endorse [Ca 2+ ] i accumulation and growth of DDR-2/α-SMA-expressing myofibroblasts from adult rat ventricles via P2Y 4 and P2Y 2 receptors activation, respectively. Ventricular myofibroblasts also express ADP-sensitive P2Y 1 , P2Y 12 , and P2Y 13 receptors as demonstrated by immunofluorescence confocal microscopy and western blot analysis, but little information exists on ADP effects in these cells. ADP (0.003-3 mM) and its stable analogue, ADPßS (100 μM), caused fast [Ca 2+ ] i transients originated from thapsigargin-sensitive internal stores, which partially declined to a plateau sustained by capacitative Ca 2+ entry through transient receptor potential (TRP) channels inhibited by 2-APB (50 μM) and flufenamic acid (100 μM). Hydrophobic interactions between G q/11 -coupled P2Y purinoceptors and TRP channels were suggested by prevention of the ADP-induced [Ca 2+ ] i plateau following PIP 2 depletion with LiCl (10 mM) and cholesterol removal from lipid rafts with methyl-ß-cyclodextrin (2 mM). ADP [Ca 2+ ] i transients were insensitive to P2Y 1 , P2Y 12 , and P2Y 13 receptor antagonists, MRS2179 (10μM), AR-C66096 (0.1 μM), and MRS2211 (10μM), respectively, but were attenuated by suramin and reactive blue-2 (100 μM) which also blocked P2Y 4 receptors activation by UTP. Cardiac myofibroblasts growth and type I collagen production were favored upon activation of MRS2179-sensitive P2Y 1 receptors with ADP or ADPßS (30 μM). In conclusion, ADP exerts a dual role on ventricular myofibroblasts: [Ca 2+ ] i transients are mediated by fast-desensitizing P2Y 4 receptors, whereas the pro-fibrotic effect of ADP involves the P2Y 1 receptor activation. Data also show that ADP-induced capacitative Ca 2+ influx depends on phospholipase C-linked TRP channels opening in lipid raft

  18. Oral treatment with essential oil of Hyptis spicigera Lam. (Lamiaceae) reduces acute pain and inflammation in mice: Potential interactions with transient receptor potential (TRP) ion channels.

    Science.gov (United States)

    Simões, Róli Rodrigues; Coelho, Igor Dos Santos; Junqueira, Stella Célio; Pigatto, Glauce Regina; Salvador, Marcos José; Santos, Adair Roberto Soares; de Faria, Felipe Meira

    2017-03-22

    The genus Hyptis comprehends almost 400 species widespread in tropical and temperate regions of America. The use of Hyptis spicigera Lam. (Lamiaceae) is reported in traditional medicine due to its gastroprotective, anti-inflammatory and analgesic properties. The rationale of this study was to investigate the potential use of the essential oil of H. spicigera (EOHs) as analgesic. The antinociceptive effect of EOHs was verified analyzing acute nocifensive behavior of mice induced by chemical noxious stimuli [i.e., formalin and transient receptor potential (TRP) channels agonists]. We also verified the effects of EOHs on locomotor activity and motor performance in mice. Finally, we investigate the involvement of central afferent C-fibers with EOHs analgesic effect. EOHs presented antinociceptive effect at 300 and 1000mg/kg on formalin-induced pain behavior model, presenting 50% and 72% of inhibition during the first phase (ED 50 =292mg/kg), and 85% and 100% during de second phase (ED 50 =205mg/kg), respectively. Temperature of the hind paw was reduced by EOHs treatment in a dose-dependent manner; oedema was diminished only by EOHs 1000mg/kg. EOHs does not impaired locomotor activity or motor performance. For mice injected with capsaicin, a TRPV1 activator, EOHs (1000mg/kg, ED 50 =660mg/kg) showed decreased (63%) nociceptive behavior. When injected with cinnamaldehyde (TRPA1 activator), mice treated with EOHs showed 23%, 43% and 66% inhibition on nociceptive behavior (100, 300 and 1000mg/kg, respectively; ED 50 402mg/kg). When mice were injected with menthol (TRPM8 activator), EOHs showed 29%, 59% and 98% inhibition of nociceptive behavior (100, 300 and 1000mg/kg, respectively; with ED 50 =198mg/kg. Finally, when desensitized mice were injected with menthol, EOHs (300mg/kg) does not show antinociceptive effect. This study demonstrated the efficacy of EOHs on experimental models of nociception. We have found the involvement of TRP channels V1, A1 and M8 with EOHs

  19. Novel water-mediated hydrogen bonds as the structural basis for the low oxygen affinity of the blood substitute candidate rHb(alpha 96Val-->Trp).

    Science.gov (United States)

    Puius, Y A; Zou, M; Ho, N T; Ho, C; Almo, S C

    1998-06-30

    One of the most promising approaches for the development of a synthetic blood substitute has been the engineering of novel mutants of human hemoglobin (Hb) A which maintain cooperativity, but possess lowered oxygen affinity. We describe here two crystal structures of one such potential blood substitute, recombinant (r) Hb(alpha 96Val-->Trp), refined to 1.9 A resolution in an alpha-aquomet, beta-deoxy T-state, and to 2.5 A resolution in a carbonmonoxy R-state. On the basis of molecular dynamics simulations, a particular conformation had been predicted for the engineered Trp residue, and the lowered oxygen affinity had been attributed to a stabilization of the deoxy T-state interface by alpha 96Trp-beta 99Asp hydrogen bonds. Difference Fourier maps of the T-state structure clearly show that alpha 96Trp is in a conformation different from that predicted by the simulation, with its indole side chain directed away from the interface and into the central cavity. In this conformation, the indole nitrogen makes novel water-mediated hydrogen bonds across the T-state interface with beta 101Glu. We propose that these water-mediated hydrogen bonds are the structural basis for the lowered oxygen affinity of rHb(alpha 96Val-->Trp), and discuss the implications of these findings for future molecular dynamics studies and the design of Hb mutants.

  20. TRPA5, an Ankyrin Subfamily Insect TRP Channel, is Expressed in Antennae of Cydia pomonella (Lepidoptera: Tortricidae) in Multiple Splice Variants.

    Science.gov (United States)

    Cattaneo, Alberto Maria; Bengtsson, Jonas Martin; Montagné, Nicolas; Jacquin-Joly, Emmanuelle; Rota-Stabelli, Omar; Salvagnin, Umberto; Bassoli, Angela; Witzgall, Peter; Anfora, Gianfranco

    2016-01-01

    Transient receptor potential (TRP) channels are an ancient family of cation channels, working as metabotropic triggers, which respond to physical and chemical environmental cues. Perception of chemical signals mediate reproductive behaviors and is therefore an important target for sustainable management tactics against the codling moth Cydia pomonella L. (Lepidoptera: Tortricidae). However, olfactory behavior strongly depends on diel periodicity and correlation of chemical with physical cues, like temperature, and physical cues thus essentially contribute to the generation of behavioral response. From an antennal transcriptome generated by next generation sequencing, we characterized five candidate TRPs in the codling moth. The coding DNA sequence of one of these was extended to full length, and phylogenetic investigation revealed it to be orthologous of the TRPA5 genes, reported in several insect genomes as members of the insect TRPA group with unknown function but closely related to the thermal sensor pyrexia Reverse transcription PCR revealed the existence of five alternate splice forms of CpTRPA5. Identification of a novel TRPA and its splice forms in codling moth antennae open for investigation of their possible sensory roles and implications in behavioral responses related to olfaction. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

  1. TRP channel-associated factors are a novel protein family that regulates TRPM8 trafficking and activity.

    NARCIS (Netherlands)

    Gkika, D.; Lemonnier, L.; Shapovalov, G.; Gordienko, D.; Poux, C.; Bernardini, M.; Bokhobza, A.; Bidaux, G.; Degerny, C.; Verreman, K.; Guarmit, B.; Benahmed, M.; Launoit, Y. de; Bindels, R.J.M.; Fiorio Pla, A.; Prevarskaya, N.

    2015-01-01

    TRPM8 is a cold sensor that is highly expressed in the prostate as well as in other non-temperature-sensing organs, and is regulated by downstream receptor-activated signaling pathways. However, little is known about the intracellular proteins necessary for channel function. Here, we identify two

  2. The TRP Channels Pkd2, NompC, and Trpm Act in Cold-Sensing Neurons to Mediate Unique Aversive Behaviors to Noxious Cold in Drosophila.

    Science.gov (United States)

    Turner, Heather N; Armengol, Kevin; Patel, Atit A; Himmel, Nathaniel J; Sullivan, Luis; Iyer, Srividya Chandramouli; Bhattacharya, Surajit; Iyer, Eswar Prasad R; Landry, Christian; Galko, Michael J; Cox, Daniel N

    2016-12-05

    The basic mechanisms underlying noxious cold perception are not well understood. We developed Drosophila assays for noxious cold responses. Larvae respond to near-freezing temperatures via a mutually exclusive set of singular behaviors-in particular, a full-body contraction (CT). Class III (CIII) multidendritic sensory neurons are specifically activated by cold and optogenetic activation of these neurons elicits CT. Blocking synaptic transmission in CIII neurons inhibits CT. Genetically, the transient receptor potential (TRP) channels Trpm, NompC, and Polycystic kidney disease 2 (Pkd2) are expressed in CIII neurons, where each is required for CT. Misexpression of Pkd2 is sufficient to confer cold responsiveness. The optogenetic activation level of multimodal CIII neurons determines behavioral output, and visualization of neuronal activity supports this conclusion. Coactivation of cold- and heat-responsive sensory neurons suggests that the cold-evoked response circuitry is dominant. Our Drosophila model will enable a sophisticated molecular genetic dissection of cold nociceptive genes and circuits. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Calmodulin regulates a TRP channel (ADF1) and phospholipase C (PLC) to mediate elevation of cytosolic calcium during acidic stress that induces deflagellation in Chlamydomonas.

    Science.gov (United States)

    Wu, Qiong; Gao, Kang; Zheng, Shuzhi; Zhu, Xin; Liang, Yinwen; Pan, Junmin

    2018-01-29

    Calcium has been implicated in the motility, assembly, disassembly, and deflagellation of the eukaryotic flagellum or cilium (exchangeable terms). Calmodulin (CaM) is known to be critical for flagellar motility; however, it is unknown whether and how CaM is involved in other flagella-related activities. We have studied CaM in Chlamydomonas, a widely used organism for ciliary studies. CaM is present in the cell body and the flagellum, with enrichment in the basal body region. Loss of CaM causes shortening of the nucleus basal body connector and impairs flagellar motility and assembly but not flagellar disassembly. Moreover, the cam mutant is defective in pH shock-induced deflagellation. The mutant deflagellates, however, upon mechanical shearing and treatment with mastoparan or detergent undergo permeabilization in the presence of calcium, indicating the cam mutant is defective in elevations of cytosolic calcium induced by pH shock, rather than by the deflagellation machinery. Indeed, the cam mutant fails to produce inositol 1,4,5-trisphosphate. Biochemical and genetic analysis showed that CaM does not directly activate PLC. Furthermore, CaM interacts with ADF1, a transient receptor channel that functions in acid-induced calcium entry. Thus, CaM is a critical regulator of flagellar activities especially those involved in modulating calcium homeostasis during acidic stress.-Wu, Q., Gao, K., Zheng, S., Zhu, X., Liang, Y., Pan, J. Calmodulin regulates a TRP channel (ADF1) and phospholipase C (PLC) to mediate elevation of cytosolic calcium during acidic stress that induces deflagellation in Chlamydomonas.

  4. Structure-activity relationship studies on a Trp dendrimer with dual activities against HIV and enterovirus A71. Modifications on the amino acid.

    Science.gov (United States)

    Martínez-Gualda, Belén; Sun, Liang; Rivero-Buceta, Eva; Flores, Aida; Quesada, Ernesto; Balzarini, Jan; Noppen, Sam; Liekens, Sandra; Schols, Dominique; Neyts, Johan; Leyssen, Pieter; Mirabelli, Carmen; Camarasa, María-José; San-Félix, Ana

    2017-03-01

    We have recently described a new class of dendrimers with tryptophan (Trp) on the surface that show dual antiviral activities against HIV and EV71 enterovirus. The prototype compound of this family is a pentaerythritol derivative with 12 Trps on the periphery. Here we complete the structure-activity relationship studies of this family to identify key features that might be significant for the antiviral activity. With this aim, novel dendrimers containing different amino acids (aromatic and non-aromatic), tryptamine (a "decarboxylated" analogue of Trp) and N-methyl Trp on the periphery have been prepared. Dendrimer with N-Methyl Trp was the most active against HIV-1 and HIV-2 while dendrimer with tyrosine was endowed with the most potent antiviral activity against EV71. This tyrosine dendrimer proved to inhibit a large panel of EV71 clinical isolates (belonging to different clusters) in the low nanomolar/high picomolar range. In addition, a new synthetic procedure (convergent approach) has been developed for the synthesis of the prototype and some other dendrimers. This convergent approach proved more efficient (higher yields, easier purification) than the divergent approach previously reported. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Copper-induced activation of TRP channels promotes extracellular calcium entry and activation of CaMs and CDPKs leading to copper entry and membrane depolarization in Ulva compressa

    Directory of Open Access Journals (Sweden)

    Melissa eGómez

    2015-03-01

    Full Text Available In order to identify channels involved in membrane depolarization, Ulva compressa was incubated with agonists of TRP channels C5, A1 and V1 and the level of intracellular calcium was detected. Agonists of TRPC5, A1 and V1 induced increases in intracellular calcium at 4, 9 and 12 min of exposure, respectively, and antagonists of TRPC5, A1 and V1 corresponding to SKF-96365 (SKF, HC-030031 (HC and capsazepin (CPZ, respectively, inhibited calcium increases indicating that functional TRPs exist in U. compressa. In addition, copper excess induced increases in intracellular calcium at 4, 9 and 12 min which were inhibited by SKF, HC and CPZ, respectively, indicating that copper activate TRPC5, A1 and V1 channels. Moreover, copper-induced calcium increases were inhibited by EGTA, a non-permeable calcium chelating agent, but not by thapsigargin, an inhibitor of endoplasmic reticulum (ER calcium ATPase, indicating that activation of TRPs leads to extracellular calcium entry. Furthermore, copper-induced calcium increases were not inhibited by W-7, an inhibitor of CaMs, and staurosporine, an inhibitor of CDPKs, indicating that extracellular calcium entry did not require CaMs and CDPKs activation. In addition, copper induced membrane depolarization events at 4, 8 and 11 min and these events were inhibited by SKF, HC, CPZ and bathocuproine, a specific copper chelating agent, indicating copper entry through TRP channels leading to membrane depolarization. Moreover, membrane depolarization events were inhibited by W-7 and staurosporine, indicating that CaMs and CDPKs are required in order to activate TRPs to allow copper entry. Thus, light-dependent copper-induced activation TRPC5, A1 and V1 promotes extracellular calcium entry leading to activation of CaMs and CDPKs which, in turn, promotes copper entry through these TRP channels leading to membrane depolarization.

  6. "TRP inflammation" relationship in cardiovascular system.

    Science.gov (United States)

    Numata, Tomohiro; Takahashi, Kiriko; Inoue, Ryuji

    2016-05-01

    Despite considerable advances in the research and treatment, the precise relationship between inflammation and cardiovascular (CV) disease remains incompletely understood. Therefore, understanding the immunoinflammatory processes underlying the initiation, progression, and exacerbation of many cardiovascular diseases is of prime importance. The innate immune system has an ancient origin and is well conserved across species. Its activation occurs in response to pathogens or tissue injury. Recent studies suggest that altered ionic balance, and production of noxious gaseous mediators link to immune and inflammatory responses with altered ion channel expression and function. Among plausible candidates for this are transient receptor potential (TRP) channels that function as polymodal sensors and scaffolding proteins involved in many physiological and pathological processes. In this review, we will first focus on the relevance of TRP channel to both exogenous and endogenous factors related to innate immune response and transcription factors related to sustained inflammatory status. The emerging role of inflammasome to regulate innate immunity and its possible connection to TRP channels will also be discussed. Secondly, we will discuss about the linkage of TRP channels to inflammatory CV diseases, from a viewpoint of inflammation in a general sense which is not restricted to the innate immunity. These knowledge may serve to provide new insights into the pathogenesis of various inflammatory CV diseases and their novel therapeutic strategies.

  7. BKCa-Channel Structure and Function

    Science.gov (United States)

    Cox, Daniel H.

    Among ion channels, the large-conductance Ca2+-activated K+ channel (BKCa channel) is in many ways unique. It has a very large single-channel conductance—ten times that of most vertebrate K+ channels—and yet it maintains strict K+ selectivity. It senses as little as 200 nM Ca2+, but it contains no consensus Ca2+-binding motifs, and it is the only channel to be activated by both intracellular Ca2+ and membrane voltage. In fact, there is a synergy between these stimuli such that the higher the internal Ca2+ concentration ([Ca2+]), the smaller the depolarization needed to activate the channel. Furthermore, the BKCa channel has its own brand of auxiliary subunits that profoundly affect gating. In this chapter, I will discuss what is understood about the origins of these properties in terms of allosteric models and channel structure. At the outset, however, I should say that there is not yet a crystal structure of the BKCa channel or any of its components, so much of the current thinking about BKCa-channel structure relies on analogy to other channels.

  8. Selectivity and evolutionary divergence of metabotropic glutamate receptors for endogenous ligands and G proteins coupled to phospholipase C or TRP channels.

    Science.gov (United States)

    Kang, Hye Jin; Menlove, Kit; Ma, Jianpeng; Wilkins, Angela; Lichtarge, Olivier; Wensel, Theodore G

    2014-10-24

    To define the upstream and downstream signaling specificities of metabotropic glutamate receptors (mGluR), we have examined the ability of representative mGluR of group I, II, and III to be activated by endogenous amino acids and catalyze activation of G proteins coupled to phospholipase C (PLC), or activation of G(i/o) proteins coupled to the ion channel TRPC4β. Fluorescence-based assays have allowed us to observe interactions not previously reported or clearly identified. We have found that the specificity for endogenous amino acids is remarkably stringent. Even at millimolar levels, structurally similar compounds do not elicit significant activation. As reported previously, the clear exception is L-serine-O-phosphate (L-SOP), which strongly activates group III mGluR, especially mGluR4,-6,-8 but not group I or II mGluR. Whereas L-SOP cannot activate mGluR1 or mGluR2, it acts as a weak antagonist for mGluR1 and a potent antagonist for mGluR2, suggesting that co-recognition of L-glutamate and L-SOP arose early in evolution, and was followed later by divergence of group I and group II mGluR versus group III in l-SOP responses. mGluR7 has low affinity and efficacy for activation by both L-glutamate and L-SOP. Molecular docking studies suggested that residue 74 corresponding to lysine in mGluR4 and asparagine in mGluR7 might play a key role, and, indeed, mutagenesis experiments demonstrated that mutating this residue to lysine in mGluR7 enhances the potency of L-SOP. Experiments with pertussis toxin and dominant-negative Gα(i/o) proteins revealed that mGluR1 couples strongly to TRPC4β through Gα(i/o), in addition to coupling to PLC through Gα(q/11). © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Selectivity and Evolutionary Divergence of Metabotropic Glutamate Receptors for Endogenous Ligands and G Proteins Coupled to Phospholipase C or TRP Channels*

    Science.gov (United States)

    Kang, Hye Jin; Menlove, Kit; Ma, Jianpeng; Wilkins, Angela; Lichtarge, Olivier; Wensel, Theodore G.

    2014-01-01

    To define the upstream and downstream signaling specificities of metabotropic glutamate receptors (mGluR), we have examined the ability of representative mGluR of group I, II, and III to be activated by endogenous amino acids and catalyze activation of G proteins coupled to phospholipase C (PLC), or activation of Gi/o proteins coupled to the ion channel TRPC4β. Fluorescence-based assays have allowed us to observe interactions not previously reported or clearly identified. We have found that the specificity for endogenous amino acids is remarkably stringent. Even at millimolar levels, structurally similar compounds do not elicit significant activation. As reported previously, the clear exception is l-serine-O-phosphate (l-SOP), which strongly activates group III mGluR, especially mGluR4,-6,-8 but not group I or II mGluR. Whereas l-SOP cannot activate mGluR1 or mGluR2, it acts as a weak antagonist for mGluR1 and a potent antagonist for mGluR2, suggesting that co-recognition of l-glutamate and l-SOP arose early in evolution, and was followed later by divergence of group I and group II mGluR versus group III in l-SOP responses. mGluR7 has low affinity and efficacy for activation by both l-glutamate and l-SOP. Molecular docking studies suggested that residue 74 corresponding to lysine in mGluR4 and asparagine in mGluR7 might play a key role, and, indeed, mutagenesis experiments demonstrated that mutating this residue to lysine in mGluR7 enhances the potency of l-SOP. Experiments with pertussis toxin and dominant-negative Gαi/o proteins revealed that mGluR1 couples strongly to TRPC4β through Gαi/o, in addition to coupling to PLC through Gαq/11. PMID:25193666

  10. Computational study of retro Trp-cage

    Czech Academy of Sciences Publication Activity Database

    Vymětal, Jiří; Bathula, S. R.; Žídek, L.; Černý, Jiří; Sklenář, V.; Vondrášek, Jiří

    2012-01-01

    Roč. 12, č. 1 (2012), s. 54-55 ISSN 1210-8529. [10th Discussions in Structural Molecular Biology . 22.03.2012-24.03.2012, Nové Hrady] Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50520701 Keywords : TRP-cage Subject RIV: CF - Physical ; Theoretical Chemistry

  11. AISI/DOE Technology Roadmap Program: TRP 9732Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures

    Energy Technology Data Exchange (ETDEWEB)

    Srdan Simunovic; Gustavo Aramayo

    2002-01-31

    The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of Ultra Light Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. Crash modeling simulations show a clear effect of strain-rate sensitivity on high strength steel (HSS) intensive vehicle. The influence of a strain-rate model can be an incremental sensitivity due to the increased flow stress when similar structure collapse modes are predicted. However, significant differences in crash energy management capacity can be predicted if the change in loading on members alters the predicted collapse mode of the structure. From the material substitution study it can be concluded that HSS material substitution cannot be performed on the basis of the material yield point only and that, especially for advanced HSS vehicle designs, the entire region of material plastic response has to be considered. However, the problem of modeling of the overall dynamic crush process still remains open and requires further experimental and theoretical investigation. Crash modeling simulations show a moderate effect of forming on overall crash performance. The design is the determining factor on the vehicle performance and, therefore, the results of this research cannot provide measures that can be used in a general case. However, it has been shown that for materials that have modest strain hardening, the forming effect is observable and that when more complex forming operations are used, especially in combination with rapid strain hardening materials, forming effects should be taken in the consideration in the computational crash models. crash compatibility study between ULSAB and cars of similar geometric characteristics have shown that the U LSAB

  12. Gamma-quantum channeling in laminated structures

    International Nuclear Information System (INIS)

    Vinetskij, V.L.; Fajngol'd, M.I.

    1979-01-01

    The phenomenon of the neutral particle (gamma-quanta) channeling in a laminated system (a stack of layers with different electron densities, where the corresponding refraction index serves as a potential) is considered. The examination is carried out in the framework of geometrical optics. A case is analyzed when the quantum wavelength is less than the atomic radius (lambda 0 ). It is obtained that the maximum channeling angle is independent of the period of layers and for lambda=10 -9 -10 -10 cm it amounts to 10 -4 -10 -5 . The approximation under consideration can be applied for long-period systems, particularly, for amorphous media of light atoms, periodically doped with atoms of heavier elements (laminated minerals, disordered alloys, polymers, some plastics and so on). Chenneling in similar structures made of cylindrical layers is considered [ru

  13. Smooth manifold structure for extreme channels

    Science.gov (United States)

    Iten, Raban; Colbeck, Roger

    2018-01-01

    A quantum channel from a system A of dimension dA to a system B of dimension dB is a completely positive trace-preserving map from complex dA × dA to dB × dB matrices, and the set of all such maps with Kraus rank r has the structure of a smooth manifold. We describe this set in two ways. First, as a quotient space of (a subset of) the rdB × dA dimensional Stiefel manifold. Second, as the set of all Choi-states of a fixed rank r. These two descriptions are topologically equivalent. This allows us to show that the set of all Choi-states corresponding to extreme channels from system A to system B of a fixed Kraus rank r is a smooth submanifold of dimension 2 r dAdB-dA2-r2 of the set of all Choi-states of rank r. As an application, we derive a lower bound on the number of parameters required for a quantum circuit topology to be able to approximate all extreme channels from A to B arbitrarily well.

  14. Water channel structures analysed by electron crystallography.

    Science.gov (United States)

    Tani, Kazutoshi; Fujiyoshi, Yoshinori

    2014-05-01

    The mechanisms underlying water transport through aquaporin (AQP) have been debated for two decades. The water permeation phenomenon of AQP seems inexplicable because the Grotthuss mechanism does not allow for simultaneous fast water permeability and inhibition of proton transfer through the hydrogen bonds of water molecules. The AQP1 structure determined by electron crystallography provided the first insights into the proton exclusion mechanism despite fast water permeation. Although several studies have provided clues about the mechanism based on the AQP structure, each proposed mechanism remains incomplete. The present review is focused on AQP function and structure solved by electron crystallography in an attempt to fill the gaps between the findings in the absence and presence of lipids. Many AQP structures can be superimposed regardless of the determination method. The AQP fold is preserved even under conditions lacking lipids, but the water arrangement in the channel pore differs. The differences might be explained by dipole moments formed by the two short helices in the lipid bilayer. In addition, structure analyses of double-layered two-dimensional crystals of AQP suggest an array formation and cell adhesive function. Electron crystallography findings not only have contributed to resolve some of the water permeation mechanisms, but have also elucidated the multiple functions of AQPs in the membrane. The roles of AQPs in the brain remain obscure, but their multiple activities might be important in the regulation of brain and other biological functions. This article is part of a Special Issue entitled Aquaporins. © 2013.

  15. Trp[superscript 2313]-His[superscript 2315] of Factor VIII C2 Domain Is Involved in Membrane Binding Structure of a Complex Between the C[subscript 2] Domain and an Inhibitor of Membrane Binding

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhuo; Lin, Lin; Yuan, Cai; Nicolaes, Gerry A.F.; Chen, Liqing; Meehan, Edward J.; Furie, Bruce; Furie, Barbara; Huang, Mingdong (Harvard-Med); (UAH); (Maastricht); (Chinese Aca. Sci.)

    2010-11-03

    Factor VIII (FVIII) plays a critical role in blood coagulation by forming the tenase complex with factor IXa and calcium ions on a membrane surface containing negatively charged phospholipids. The tenase complex activates factor X during blood coagulation. The carboxyl-terminal C2 domain of FVIII is the main membrane-binding and von Willebrand factor-binding region of the protein. Mutations of FVIII cause hemophilia A, whereas elevation of FVIII activity is a risk factor for thromboembolic diseases. The C2 domain-membrane interaction has been proposed as a target of intervention for regulation of blood coagulation. A number of molecules that interrupt FVIII or factor V (FV) binding to cell membranes have been identified through high throughput screening or structure-based design. We report crystal structures of the FVIII C2 domain under three new crystallization conditions, and a high resolution (1.15 {angstrom}) crystal structure of the FVIII C2 domain bound to a small molecular inhibitor. The latter structure shows that the inhibitor binds to the surface of an exposed {beta}-strand of the C2 domain, Trp{sup 2313}-His{sup 2315}. This result indicates that the Trp{sup 2313}-His{sup 2315} segment is an important constituent of the membrane-binding motif and provides a model to understand the molecular mechanism of the C2 domain membrane interaction.

  16. Na+ channel function, regulation, structure, trafficking and sequestration

    Science.gov (United States)

    Chen-Izu, Ye; Shaw, Robin M; Pitt, Geoffrey S; Yarov-Yarovoy, Vladimir; Sack, Jon T; Abriel, Hugues; Aldrich, Richard W; Belardinelli, Luiz; Cannell, Mark B; Catterall, William A; Chazin, Walter J; Chiamvimonvat, Nipavan; Deschenes, Isabelle; Grandi, Eleonora; Hund, Thomas J; Izu, Leighton T; Maier, Lars S; Maltsev, Victor A; Marionneau, Celine; Mohler, Peter J; Rajamani, Sridharan; Rasmusson, Randall L; Sobie, Eric A; Clancy, Colleen E; Bers, Donald M

    2015-01-01

    This paper is the second of a series of three reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on Na+ channel function and regulation, Na+ channel structure and function, and Na+ channel trafficking, sequestration and complexing. PMID:25772290

  17. Mathematical structure of arrangement channel quantum mechanics

    International Nuclear Information System (INIS)

    Evans, J.W.

    1981-01-01

    A non-Hermitian matrix Hamiltonian H appears in the wavefunction form of a variety of many-body scattering theories. This operator acts on an arrangement channel Banach or Hilbert space C = direct-sum/sub α/H where H is the N-particle Hilbert space and α are certain arrangement channels. Various aspects of the spectral and semigroup theory for H are considered. The normalizable and weak (wavelike) eigenvectors of H are naturally characterized as either physical or spurious. Typically H is scalar spectral and ''equivalent'' to H on an H-invariant subspace of physical solutions. If the eigenvectors form a basis, by constructing a suitable biorthogonal system, we show that H is scalar spectral on C. Other concepts including the channel space observables, trace class and trace, density matrix and Moeller operators are developed. The sense in which the theory provides a ''representation'' of N-particle quantum mechanics and its equivalence to the usual Hilbert space theory is clarified

  18. The Seventh Annual Ion Channel Retreat Vancouver, Canada, June 29-July 1, 2009.

    Science.gov (United States)

    Brugger, Saranna; Kennedy, Susannah; King, Noel

    2010-02-01

    Seven years ago, Aurora Biomed Inc. (Vancouver, BC) recognized the need to create a forum for scientific discourse spanning the spectrum of ion channel disciplines. Since then, researchers from both academia and industry have been invited each year to share their knowledge on the advancement of ion channel research and technology, drug discovery, and safety pharmacology. Aurora Biomed's 2009 Retreat continued this tradition by covering a variety of topics including Ion Channels as Disease and Pain Targets, TRP Ion Channels, Ion Channel Screening Technologies, Ion Channels in Safety Pharmacology, Structure & Function of Ion Channels, Ion Channels in Disease Pathology, and New Horizons in Life Sciences.

  19. Crystal structures of the TRIC trimeric intracellular cation channel orthologues.

    Science.gov (United States)

    Kasuya, Go; Hiraizumi, Masahiro; Maturana, Andrés D; Kumazaki, Kaoru; Fujiwara, Yuichiro; Liu, Keihong; Nakada-Nakura, Yoshiko; Iwata, So; Tsukada, Keisuke; Komori, Tomotaka; Uemura, Sotaro; Goto, Yuhei; Nakane, Takanori; Takemoto, Mizuki; Kato, Hideaki E; Yamashita, Keitaro; Wada, Miki; Ito, Koichi; Ishitani, Ryuichiro; Hattori, Motoyuki; Nureki, Osamu

    2016-12-01

    Ca 2+ release from the sarcoplasmic reticulum (SR) and endoplasmic reticulum (ER) is crucial for muscle contraction, cell growth, apoptosis, learning and memory. The trimeric intracellular cation (TRIC) channels were recently identified as cation channels balancing the SR and ER membrane potentials, and are implicated in Ca 2+ signaling and homeostasis. Here we present the crystal structures of prokaryotic TRIC channels in the closed state and structure-based functional analyses of prokaryotic and eukaryotic TRIC channels. Each trimer subunit consists of seven transmembrane (TM) helices with two inverted repeated regions. The electrophysiological, biochemical and biophysical analyses revealed that TRIC channels possess an ion-conducting pore within each subunit, and that the trimer formation contributes to the stability of the protein. The symmetrically related TM2 and TM5 helices are kinked at the conserved glycine clusters, and these kinks are important for the channel activity. Furthermore, the kinks of the TM2 and TM5 helices generate lateral fenestrations at each subunit interface. Unexpectedly, these lateral fenestrations are occupied with lipid molecules. This study provides the structural and functional framework for the molecular mechanism of this ion channel superfamily.

  20. High transformer ratio of multi-channel dielectric wakefield structures

    Energy Technology Data Exchange (ETDEWEB)

    Shchelkunov, Sergey V., E-mail: sergey.shchelkunov@gmail.com [Omega-P R& D, Inc, CT 06511 (United States); Yale University, CT (United States); Marshall, Thomas C. [Omega-P R& D, Inc, CT 06511 (United States); Sotnikov, Gennadij V. [NSC Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Hirshfield, Jay L. [Omega-P R& D, Inc, CT 06511 (United States)

    2016-09-01

    Dielectric wakefield (DWA) accelerator concepts are receiving attention on account of their promising performance, mechanical simplicity, and anticipated low cost. Interest in DWA physics directed toward an advanced high-gradient accelerator has been enhanced by a finding that some dielectrics can withstand very high fields (>1 GV/m) for the short times during the passage of charged bunches along dielectric-lined channels. In a two-channel structure, a drive bunch train propagates in a first channel, and in the second adjacent channel where a high gradient wakefield develops, a witness bunch is accelerated. Compared with single-channel DWA's, a two-beam accelerator delivers a high transformer ratio, and thereby reduces the number of drive beam sections needed to achieve a given final test beam energy. An overview of multi-channel DWA structures will be given, with an emphasis on two-channel structures, presenting their advantages and drawbacks, and potential impact on the field. Studies aimed to examine charging rate and charge distribution in a thin walled dielectric wakefield accelerator from a passing charge bunch and the physics of conductivity and discharge phenomena in dielectric materials useful for such accelerator applications are presented in a separate paper in the EAAC-2015 conference proceedings.

  1. In depth analysis on the binding sites of adamantane derivatives in HCV (hepatitis C virus p7 channel based on the NMR structure.

    Directory of Open Access Journals (Sweden)

    Qi-Shi Du

    Full Text Available BACKGROUND: The recently solved solution structure of HCV (hepatitis C virus p7 ion channel provides a solid structure basis for drug design against HCV infection. In the p7 channel the ligand amantadine (or rimantadine was determined in a hydrophobic pocket. However the pharmocophore (-NH2 of the ligand was not assigned a specific binding site. RESULTS: The possible binding sites for amino group of adamantane derivatives is studied based on the NMR structure of p7 channel using QM calculation and molecular modeling. In the hydrophobic cavity and nearby three possible binding sites are proposed: His17, Phe20, and Trp21. The ligand binding energies at the three binding sites are studied using high level QM method CCSD(T/6-311+G(d,p and AutoDock calculations, and the interaction details are analyzed. The potential application of the binding sites for rational inhibitor design are discussed. CONCLUSIONS: Some useful viewpoints are concluded as follows. (1 The amino group (-NH2 of adamantane derivatives is protonated (-NH3+, and the positively charged cation may form cation-π interactions with aromatic amino acids. (2 The aromatic amino acids (His17, Phe20, and Trp21 are the possible binding sites for the protonated amino group (-NH3+ of adamantane derivatives, and the cation-π bond energies are 3 to 5 times stronger than the energies of common hydrogen bonds. (3 The higher inhibition potent of rimantadine than amantadine probably because of its higher pKa value (pKa = 10.40 and the higher positive charge in the amino group. The potential application of p7 channel structure for inhibitor design is discussed.

  2. Influence of Trp flipping on carbohydrate binding in lectins. An example on Aleuria aurantia lectin AAL.

    Directory of Open Access Journals (Sweden)

    Josef Houser

    Full Text Available Protein-carbohydrate interactions are very often mediated by the stacking CH-π interactions involving the side chains of aromatic amino acids such as tryptophan (Trp, tyrosine (Tyr or phenylalanine (Phe. Especially suitable for stacking is the Trp residue. Analysis of the PDB database shows Trp stacking for 265 carbohydrate or carbohydrate like ligands in 5 208 Trp containing motives. An appropriate model system to study such an interaction is the AAL lectin family where the stacking interactions play a crucial role and are thought to be a driving force for carbohydrate binding. In this study we present data showing a novel finding in the stacking interaction of the AAL Trp side chain with the carbohydrate. High resolution X-ray structure of the AAL lectin from Aleuria aurantia with α-methyl-l-fucoside ligand shows two possible Trp side chain conformations with the same occupation in electron density. The in silico data shows that the conformation of the Trp side chain does not influence the interaction energy despite the fact that each conformation creates interactions with different carbohydrate CH groups. Moreover, the PDB data search shows that the conformations are almost equally distributed across all Trp-carbohydrate complexes, which would suggest no substantial preference for one conformation over another.

  3. Structure and Mechanism of a Pentameric Formate Channel

    Energy Technology Data Exchange (ETDEWEB)

    Waight, A.; Love, J; Wang, D

    2010-01-01

    Formate transport across the inner membrane is a critical step in anaerobic bacterial respiration. Members of the formate/nitrite transport protein family function to shuttle substrate across the cytoplasmic membrane. In bacterial pathogens, the nitrite transport protein is involved in protecting bacteria from peroxynitrite released by host macrophages. We have determined the 2.13-{angstrom} structure of the formate channel FocA from Vibrio cholerae, which reveals a pentamer in which each monomer possesses its own substrate translocation pore. Unexpectedly, the fold of the FocA monomer resembles that found in water and glycerol channels. The selectivity filter in FocA consists of a cytoplasmic slit and a central constriction ring. A 2.5-{angstrom} high-formate structure shows two formate ions bound to the cytoplasmic slit via both hydrogen bonding and van der Waals interactions, providing a structural basis for the substrate selectivity of the channel.

  4. Structure of a eukaryotic cyclic nucleotide-gated channel

    Science.gov (United States)

    Li, Minghui; Zhou, Xiaoyuan; Wang, Shu; Michailidis, Ioannis; Gong, Ye; Su, Deyuan; Li, Huan; Li, Xueming; Yang, Jian

    2018-01-01

    Summary Cyclic nucleotide-gated (CNG) channels are essential for vision and olfaction. They belong to the voltage-gated ion channel superfamily but their activities are controlled by intracellular cyclic nucleotides instead of transmembrane voltage. Here we report a 3.5 Å-resolution single-particle electron cryomicroscopy structure of a CNG channel from C. elegans in the cGMP-bound open state. The channel has an unusual voltage-sensor-like domain (VSLD), accounting for its deficient voltage dependence. A C-terminal linker connecting S6 and the cyclic nucleotide-binding domain interacts directly with both the VSLD and pore domain, forming a gating ring that couples conformational changes triggered by cyclic nucleotide binding to the gate. The selectivity filter is lined by the carboxylate side chains of a functionally important glutamate and three rings of backbone carbonyls. This structure provides a new framework for understanding mechanisms of ion permeation, gating and channelopathy of CNG channels and cyclic nucleotide modulation of related channels. PMID:28099415

  5. Cryo-EM structures of the mammalian endo-lysosomal TRPML1 channel elucidate the combined regulation mechanism

    Directory of Open Access Journals (Sweden)

    Sensen Zhang

    2017-09-01

    Full Text Available Abstract TRPML1 channel is a non-selective group-2 transient receptor potential (TRP channel with Ca2+ permeability. Located mainly in late endosome and lysosome of all mammalian cell types, TRPML1 is indispensable in the processes of endocytosis, membrane trafficking, and lysosome biogenesis. Mutations of TRPML1 cause a severe lysosomal storage disorder called mucolipidosis type IV (MLIV. In the present study, we determined the cryo-electron microscopy (cryo-EM structures of Mus musculus TRPML1 (mTRPML1 in lipid nanodiscs and Amphipols. Two distinct states of mTRPML1 in Amphipols are added to the closed state, on which could represent two different confirmations upon activation and regulation. The polycystin-mucolipin domain (PMD may sense the luminal/extracellular stimuli and undergo a “move upward” motion during endocytosis, thus triggering the overall conformational change in TRPML1. Based on the structural comparisons, we propose TRPML1 is regulated by pH, Ca2+, and phosphoinositides in a combined manner so as to accommodate the dynamic endocytosis process.

  6. Fluorescence kinetics of Trp-Trp dipeptide and its derivatives in water via ultrafast fluorescence spectroscopy.

    Science.gov (United States)

    Jia, Menghui; Yi, Hua; Chang, Mengfang; Cao, Xiaodan; Li, Lei; Zhou, Zhongneng; Pan, Haifeng; Chen, Yan; Zhang, Sanjun; Xu, Jianhua

    2015-08-01

    Ultrafast fluorescence dynamics of Tryptophan-Tryptophan (Trp-Trp/Trp2) dipeptide and its derivatives in water have been investigated using a picosecond resolved time correlated single photon counting (TCSPC) apparatus together with a femtosecond resolved upconversion spectrophotofluorometer. The fluorescence decay profiles at multiple wavelengths were fitted by a global analysis technique. Nanosecond fluorescence kinetics of Trp2, N-tert-butyl carbonyl oxygen-N'-aldehyde group-l-tryptophan-l-tryptophan (NBTrp2), l-tryptophan-l-tryptophan methyl ester (Trp2Me), and N-acetyl-l-tryptophan-l-tryptophan methyl ester (NATrp2Me) exhibit multi-exponential decays with the average lifetimes of 1.99, 3.04, 0.72 and 1.22ns, respectively. Due to the intramolecular interaction between two Trp residues, the "water relaxation" lifetime was observed around 4ps, and it is noticed that Trp2 and its derivatives also exhibit a new decay with a lifetime of ∼100ps, while single-Trp fluorescence decay in dipeptides/proteins shows 20-30ps. The intramolecular interaction lifetime constants of Trp2, NBTrp2, Trp2Me and NATrp2Me were then calculated to be 3.64, 0.93, 11.52 and 2.40ns, respectively. Candidate mechanisms (including heterogeneity, solvent relaxation, quasi static self-quenching or ET/PT quenching) have been discussed. Copyright © 2015. Published by Elsevier B.V.

  7. Channel flow structure measurements using particle image velocimetry

    International Nuclear Information System (INIS)

    Norazizi Mohamed; Noraeini Mokhtar; Aziz Ibrahim; Ramli Abu Hassan

    1996-01-01

    Two different flow structures in a laboratory channel were examined using a flow visualization technique, known as Particle Image Velocimetry (PIV). The first channel flow structure was that of a steady flow over a horizontal channel bottom. Photographs of particle displacements were taken in the boundary layer in a plane parallel to the flow. These photographs were analyzed to give simultaneous measurements of two components of the velocity at hundreds of points in the plane. Averaging these photographs gave the velocity profile a few millimeters from the bottom of the channel to the water surface. The results gave good agreement with the known boundary layer theory. This technique is extended to the study of the structure under a progressive wave in the channel. A wavelength of the propagating wave is divided into sections by photographing it continously for a number of frames. Each frame is analyzed and a velocity field under this wave at various phase points were produced with their respective directions. The results show that velocity vectors in a plane under the wave could be achieved instantaneously and in good agreement with the small amplitude wave theory

  8. Horticultural marketing channels in Kenya : structure and development

    NARCIS (Netherlands)

    Dijkstra, T.

    1997-01-01

    This study analyses the structure and development of horticultural marketing channels in Kenya. It is based primarily on a farm survey among some 500 farmers in Nyandarua, Kisii and Taita Taveta Districts and a trade survey of about 750 horticultural traders in 18 different market places.

  9. Structural and functional diversity of acidic scorpion potassium channel toxins.

    Directory of Open Access Journals (Sweden)

    Zong-Yun Chen

    Full Text Available BACKGROUND: Although the basic scorpion K(+ channel toxins (KTxs are well-known pharmacological tools and potential drug candidates, characterization the acidic KTxs still has the great significance for their potential selectivity towards different K(+ channel subtypes. Unfortunately, research on the acidic KTxs has been ignored for several years and progressed slowly. PRINCIPAL FINDINGS: Here, we describe the identification of nine new acidic KTxs by cDNA cloning and bioinformatic analyses. Seven of these toxins belong to three new α-KTx subfamilies (α-KTx28, α-KTx29, and α-KTx30, and two are new members of the known κ-KTx2 subfamily. ImKTx104 containing three disulfide bridges, the first member of the α-KTx28 subfamily, has a low sequence homology with other known KTxs, and its NMR structure suggests ImKTx104 adopts a modified cystine-stabilized α-helix-loop-β-sheet (CS-α/β fold motif that has no apparent α-helixs and β-sheets, but still stabilized by three disulfide bridges. These newly described acidic KTxs exhibit differential pharmacological effects on potassium channels. Acidic scorpion toxin ImKTx104 was the first peptide inhibitor found to affect KCNQ1 channel, which is insensitive to the basic KTxs and is strongly associated with human cardiac abnormalities. ImKTx104 selectively inhibited KCNQ1 channel with a K(d of 11.69 µM, but was less effective against the basic KTxs-sensitive potassium channels. In addition to the ImKTx104 toxin, HeTx204 peptide, containing a cystine-stabilized α-helix-loop-helix (CS-α/α fold scaffold motif, blocked both Kv1.3 and KCNQ1 channels. StKTx23 toxin, with a cystine-stabilized α-helix-loop-β-sheet (CS-α/β fold motif, could inhibit Kv1.3 channel, but not the KCNQ1 channel. CONCLUSIONS/SIGNIFICANCE: These findings characterize the structural and functional diversity of acidic KTxs, and could accelerate the development and clinical use of acidic KTxs as pharmacological tools and

  10. Shear and shearless Lagrangian structures in compound channels

    Science.gov (United States)

    Enrile, F.; Besio, G.; Stocchino, A.

    2018-03-01

    Transport processes in a physical model of a natural stream with a composite cross-section (compound channel) are investigated by means of a Lagrangian analysis based on nonlinear dynamical system theory. Two-dimensional free surface Eulerian experimental velocity fields of a uniform flow in a compound channel form the basis for the identification of the so-called Lagrangian Coherent Structures. Lagrangian structures are recognized as the key features that govern particle trajectories. We seek for two particular class of Lagrangian structures: Shear and shearless structures. The former are generated whenever the shear dominates the flow whereas the latter behave as jet-cores. These two type of structures are detected as ridges and trenches of the Finite-Time Lyapunov Exponents fields, respectively. Besides, shearlines computed applying the geodesic theory of transport barriers mark Shear Lagrangian Coherent Structures. So far, the detection of these structures in real experimental flows has not been deeply investigated. Indeed, the present results obtained in a wide range of the controlling parameters clearly show a different behaviour depending on the shallowness of the flow. Shear and Shearless Lagrangian Structures detected from laboratory experiments clearly appear as the flow develops in shallow conditions. The presence of these Lagrangian Structures tends to fade in deep flow conditions.

  11. TRP and Rhodopsin Transport Depends on Dual XPORT ER Chaperones Encoded by an Operon

    Directory of Open Access Journals (Sweden)

    Zijing Chen

    2015-10-01

    Full Text Available TRP channels and G protein-coupled receptors (GPCRs play critical roles in sensory reception. However, the identities of the chaperones that assist GPCRs in translocating from the endoplasmic reticulum (ER are limited, and TRP ER chaperones are virtually unknown. The one exception for TRPs is Drosophila XPORT. Here, we show that the xport locus is bicistronic and encodes unrelated transmembrane proteins, which enable the signaling proteins that initiate and culminate phototransduction, rhodopsin 1 (Rh1 and TRP, to traffic to the plasma membrane. XPORT-A and XPORT-B are ER proteins, and loss of either has a profound impact on TRP and Rh1 targeting to the light-sensing compartment of photoreceptor cells. XPORT-B complexed in vivo with the Drosophila homolog of the mammalian HSP70 protein, GRP78/BiP, which, in turn, associated with Rh1. Our work highlights a coordinated network of chaperones required for the biosynthesis of the TRP channel and rhodopsin in Drosophila photoreceptor cells.

  12. Exploring the Structure of the Voltage-gated Na+ Channel by an Engineered Drug Access Pathway to the Receptor Site for Local Anesthetics*

    Science.gov (United States)

    Lukacs, Peter; Gawali, Vaibhavkumar S.; Cervenka, Rene; Ke, Song; Koenig, Xaver; Rubi, Lena; Zarrabi, Touran; Hilber, Karlheinz; Stary-Weinzinger, Anna; Todt, Hannes

    2014-01-01

    Despite the availability of several crystal structures of bacterial voltage-gated Na+ channels, the structure of eukaryotic Na+ channels is still undefined. We used predictions from available homology models and crystal structures to modulate an external access pathway for the membrane-impermeant local anesthetic derivative QX-222 into the internal vestibule of the mammalian rNaV1.4 channel. Potassium channel-based homology models predict amino acid Ile-1575 in domain IV segment 6 to be in close proximity to Lys-1237 of the domain III pore-loop selectivity filter. The mutation K1237E has been shown previously to increase the diameter of the selectivity filter. We found that an access pathway for external QX-222 created by mutations of Ile-1575 was abolished by the additional mutation K1237E, supporting the notion of a close spatial relationship between sites 1237 and 1575. Crystal structures of bacterial voltage-gated Na+ channels predict that the side chain of rNaV1.4 Trp-1531 of the domain IV pore-loop projects into the space between domain IV segment 6 and domain III pore-loop and, therefore, should obstruct the putative external access pathway. Indeed, mutations W1531A and W1531G allowed for exceptionally rapid access of QX-222. In addition, W1531G created a second non-selective ion-conducting pore, bypassing the outer vestibule but probably merging into the internal vestibule, allowing for control by the activation gate. These data suggest a strong structural similarity between bacterial and eukaryotic voltage-gated Na+ channels. PMID:24947510

  13. Exploring the structure of the voltage-gated Na+ channel by an engineered drug access pathway to the receptor site for local anesthetics.

    Science.gov (United States)

    Lukacs, Peter; Gawali, Vaibhavkumar S; Cervenka, Rene; Ke, Song; Koenig, Xaver; Rubi, Lena; Zarrabi, Touran; Hilber, Karlheinz; Stary-Weinzinger, Anna; Todt, Hannes

    2014-08-01

    Despite the availability of several crystal structures of bacterial voltage-gated Na(+) channels, the structure of eukaryotic Na(+) channels is still undefined. We used predictions from available homology models and crystal structures to modulate an external access pathway for the membrane-impermeant local anesthetic derivative QX-222 into the internal vestibule of the mammalian rNaV1.4 channel. Potassium channel-based homology models predict amino acid Ile-1575 in domain IV segment 6 to be in close proximity to Lys-1237 of the domain III pore-loop selectivity filter. The mutation K1237E has been shown previously to increase the diameter of the selectivity filter. We found that an access pathway for external QX-222 created by mutations of Ile-1575 was abolished by the additional mutation K1237E, supporting the notion of a close spatial relationship between sites 1237 and 1575. Crystal structures of bacterial voltage-gated Na(+) channels predict that the side chain of rNaV1.4 Trp-1531 of the domain IV pore-loop projects into the space between domain IV segment 6 and domain III pore-loop and, therefore, should obstruct the putative external access pathway. Indeed, mutations W1531A and W1531G allowed for exceptionally rapid access of QX-222. In addition, W1531G created a second non-selective ion-conducting pore, bypassing the outer vestibule but probably merging into the internal vestibule, allowing for control by the activation gate. These data suggest a strong structural similarity between bacterial and eukaryotic voltage-gated Na(+) channels. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. 1st International Conference on Hydraulic Design in Water Resources Engineering : Channels and Channel Control Structures

    CERN Document Server

    1984-01-01

    The development of water resources has proceeded at an amazing speed around the world in the last few decades. The hydraulic engineer has played his part: in constructing much larger artificial channels than ever before, larger and more sophisticated control structures, and systems of irrigation, drainage and water supply channels in which the flow by its nature is complex and unsteady requiring computer-based techniques at both the design and operation stage. It seemed appropriate to look briefly at some of the developments in hydraulic design resulting from this situation. Hence the idea of the Conference was formed. The Proceedings of the Conference show that hydraulic engineers have been able to acquire a very substantial base of design capability from the experience of the period referred to. The most outstanding development to have occurred is in the combination of physical and mathematical modelling, which in hydraulic engineering has followed a parallel path to that in other branches of engineering sc...

  15. Structural Determinants of Oligomerization of the Aquaporin-4 Channel*

    Science.gov (United States)

    Kitchen, Philip; Conner, Matthew T.; Bill, Roslyn M.; Conner, Alex C.

    2016-01-01

    The aquaporin (AQP) family of integral membrane protein channels mediate cellular water and solute flow. Although qualitative and quantitative differences in channel permeability, selectivity, subcellular localization, and trafficking responses have been observed for different members of the AQP family, the signature homotetrameric quaternary structure is conserved. Using a variety of biophysical techniques, we show that mutations to an intracellular loop (loop D) of human AQP4 reduce oligomerization. Non-tetrameric AQP4 mutants are unable to relocalize to the plasma membrane in response to changes in extracellular tonicity, despite equivalent constitutive surface expression levels and water permeability to wild-type AQP4. A network of AQP4 loop D hydrogen bonding interactions, identified using molecular dynamics simulations and based on a comparative mutagenic analysis of AQPs 1, 3, and 4, suggest that loop D interactions may provide a general structural framework for tetrameric assembly within the AQP family. PMID:26786101

  16. Structural Determinants of Oligomerization of the Aquaporin-4 Channel.

    Science.gov (United States)

    Kitchen, Philip; Conner, Matthew T; Bill, Roslyn M; Conner, Alex C

    2016-03-25

    The aquaporin (AQP) family of integral membrane protein channels mediate cellular water and solute flow. Although qualitative and quantitative differences in channel permeability, selectivity, subcellular localization, and trafficking responses have been observed for different members of the AQP family, the signature homotetrameric quaternary structure is conserved. Using a variety of biophysical techniques, we show that mutations to an intracellular loop (loop D) of human AQP4 reduce oligomerization. Non-tetrameric AQP4 mutants are unable to relocalize to the plasma membrane in response to changes in extracellular tonicity, despite equivalent constitutive surface expression levels and water permeability to wild-type AQP4. A network of AQP4 loop D hydrogen bonding interactions, identified using molecular dynamics simulations and based on a comparative mutagenic analysis of AQPs 1, 3, and 4, suggest that loop D interactions may provide a general structural framework for tetrameric assembly within the AQP family. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. An 8-Channel Wavelength MMI Demultiplexer in Slot Waveguide Structures.

    Science.gov (United States)

    Ben Zaken, Bar Baruch; Zanzury, Tal; Malka, Dror

    2016-11-01

    We propose a novel 8-channel wavelength multimode interference (MMI) demultiplexer in slot waveguide structures that operate at 1530 nm, 1535 nm, 1540 nm, 1545 nm, 1550 nm, 1555 nm, 1560 nm, and 1565 nm. Gallium nitride (GaN) surrounded by silicon (Si) was found to be a suitable material for the slot-waveguide structures. The proposed device was designed by seven 1 × 2 MMI couplers, fourteen S-bands, and one input taper. Numerical investigations were carried out on the geometrical parameters using a full vectorial-beam propagation method (FV-BPM). Simulation results show that the proposed device can transmit 8-channel that works in the whole C-band (1530-1565 nm) with low crosstalk (-19.97--13.77 dB) and bandwidth (1.8-3.6 nm). Thus, the device can be very useful in optical networking systems that work on dense wavelength division multiplexing (DWDM) technology.

  18. A Study of the Boltzmann Sequence-Structure Channel.

    Science.gov (United States)

    Magner, Abram; Kihara, Daisuke; Szpankowski, Wojciech

    2017-02-01

    We rigorously study a channel that maps sequences from a finite alphabet to self-avoiding walks in the two-dimensional grid, inspired by a model of protein folding from statistical physics and studied empirically by biophysicists. This channel, which we call the Boltzmann sequence-structure channel, is characterized by a Boltzmann/Gibbs distribution with a free parameter corresponding to temperature. In our previous work, we verified empirically that the channel capacity appears to have a phase transition for small temperature and decays to zero for high temperature. In this paper, we make some progress toward theoretically explaining these phenomena. We first estimate the conditional entropy between the input sequence and the output fold, giving an upper bound which exhibits a phase transition with respect to temperature. Next, we formulate a class of parameter settings under which the dependence between walk energies is governed by their number of shared contacts. In this setting, we derive a lower bound on the conditional entropy. This lower bound allows us to conclude that the mutual information tends to zero in a nontrivial regime of high temperature, giving some support to the empirical fact regarding capacity. Finally, we construct an example setting of the parameters of the model for which the conditional entropy is exactly calculable and which does not exhibit a phase transition.

  19. Structural Responses of a Stream Community to a Channel Relocation Using a Natural Channel Design Approach

    Science.gov (United States)

    Jack, J.; Word, D.; Daniel, W.; Pritchard, S.; Parola, A.; Vesely, B.

    2005-05-01

    Streams have been heavily impacted by historical and contemporary management practices. Restorations are seen as a way to enhance stream ecosystem integrity, but there are few restoration sites where pre- and post-restoration data are available to assess "success." In 2003, a channelized reach of Wilson Creek (Kentucky, USA) was relocated using a natural channel design approach. We compared the structural and functional responses of the stream pre- and post restoration/relocation at sites within Wilson and two reference streams. Despite the construction disturbance, water chemistry parameters such as nitrate and turbidity were nearly identical at sampling stations above and below the relocation for 2003-2004. Macroinvertebrate colonization of the relocation sites was rapid, with communities dominated by Cheumatopsyche, Perlesta and Baetis. Assessments of CPOM transport indicated that the new stream channel is more retentive of leaf and woody debris material than the pre-restoration Wilson sites or unrestored reference stream sites. The restoration of suitable habitat and the presence of "source populations" for colonization may compensate for even large-scale (but short-term) construction disturbance. More research is needed to assess the balance between the disturbance impacts of restoration installation and the long term benefits of stream ecological improvement.

  20. Structure resonances due to space charge in periodic focusing channels

    Science.gov (United States)

    Li, Chao; Jameson, R. A.

    2018-02-01

    The Vlasov-Poisson model is one of the most effective methods to study the space charge dominated beam evolution self-consistently in a periodic focusing channel. Since the approach to get the solution with this model is not trivial, previous studies are limited in degenerated conditions, either in smoothed channel (constant focusing) [I. Hofmann, Phys. Rev. E 57, 4713 (1998)] or in alternating gradient focusing channel with equal initial beam emittance condition in the degrees of freedom [I. Hofmann et al., Part. Accel. 13, 145 (1983); Chao Li et al., THOBA02, IPAC2016]. To establish a basis, we intentionally limit this article to the study of the pure transverse periodic focusing lattice with arbitrary initial beam condition, and the same lattice structure in both degrees of freedom, but with possibility of different focusing strengths. This will show the extension of the existing work. The full Hamiltonian is invoked for a pure transverse focusing lattice in various initial beam conditions, revealing different mode structure and additional modes beyond those of the degenerated cases. Application of the extended method to realistic lattices (including longitudinal accelerating elements) and further details will then reveal many new insights, and will be presented in later work.

  1. Differential localization of NT-3 and TrpM5 in glomeruli of the olfactory bulb of mice.

    Science.gov (United States)

    Rolen, S H; Salcedo, E; Restrepo, D; Finger, T E

    2014-06-01

    Olfactory sensory neurons that express transient receptor potential channel M5 (TrpM5) or neurotrophin-3 (NT-3) project to defined clusters of glomeruli situated ventrally in the main olfactory bulb. Using genetically labeled mice, we investigated whether expression of NT-3-driven βgal and TrpM5-driven GFP marked overlapping sets of glomeruli and whether expression of these markers was coordinated. Our results indicate that these markers largely characterize independent sets of olfactory sensory neuron axons and glomeruli. Further, in glomeruli in which both TrpM5-GFP and NT-3-βgal labeled axons occur, they are expressed independently. The nature of staining for these two markers also differs within glomeruli. Within each labeled TrpM5-positive glomerulus, the level of TrpM5-GFP expression was similar throughout the glomerular neuropil. In contrast, NT-3-driven βgal expression levels are heterogeneous even within heavily labeled glomeruli. In addition, a population of very small TrpM5-GFP positive glomeruli is apparent while no similar populations of NT-3-βgal glomeruli are evident. Taken together, these data suggest that TrpM5 and NT-3 characterize two largely independent receptor populations both conveying odorant information to the ventral olfactory bulb. Copyright © 2013 Wiley Periodicals, Inc.

  2. Differential Localization of NT-3- and TrpM5 in Glomeruli of the Olfactory Bulb of Mice

    Science.gov (United States)

    Rolen, S. H.; Salcedo, E.; Restrepo, D.; Finger, T. E.

    2014-01-01

    Olfactory sensory neurons that express transient receptor potential channel M5 (TrpM5) or neurotrophin-3 (NT-3) project to defined clusters of glomeruli situated ventrally in the main olfactory bulb. Using genetically labeled mice, we investigated whether expression of NT-3-driven βgal and TrpM5-driven GFP marked overlapping sets of glomeruli and whether expression of these markers was coordinated. Our results indicate that these markers largely characterize independent sets of olfactory sensory neuron axons and glomeruli. Further, in glomeruli in which both TrpM5-GFP and NT-3-βgal labeled axons occur, they are expressed independently. The nature of staining for these two markers also differs within glomeruli. Within each labeled TrpM5-positive glomerulus, the level of TrpM5-GFP expression was similar throughout the glomerular neuropil. In contrast, NT-3-driven βgal expression levels are heterogeneous even within heavily labeled glomeruli. In addition, a population of very small TrpM5-GFP positive glomeruli is apparent while no similar populations of NT-3-βgal glomeruli are evident. Taken together, these data suggest that TrpM5 and NT-3 characterize two largely independent receptor populations both conveying odorant information to the ventral olfactory bulb. PMID:24288162

  3. Coupled channels description of the α-decay fine structure

    Science.gov (United States)

    Delion, D. S.; Ren, Zhongzhou; Dumitrescu, A.; Ni, Dongdong

    2018-05-01

    We review the coupled channels approach of α transitions to excited states. The α-decaying states are identified as narrow outgoing Gamow resonances in an α-daughter potential. The real part of the eigenvalue corresponds to the Q-value, while the imaginary part determines the half of the total α-decay width. We first review the calculations describing transitions to rotational states treated by the rigid rotator model, in even–even, odd-mass and odd–odd nuclei. It is found that the semiclassical method overestimates the branching ratios to excited 4+ for some even–even α-emitters and fails in explaining the unexpected inversion of branching ratios of some odd-mass nuclei, while the coupled-channels results show good agreement with the experimental data. Then, we review the coupled channels method for α-transitions to 2+ vibrational and transitional states. We present the results of the Coherent State Model that describes in a unified way the spectra of vibrational, transitional and rotational nuclei. We evidence general features of the α-decay fine structure, namely the linear dependence between α-intensities and excitation energy, the linear correlation between the strength of the α-core interaction and spectroscopic factor, and the inverse correlation between the nuclear collectivity, given by electromagnetic transitions, and α-clustering.

  4. Pricing Decision under Dual-Channel Structure considering Fairness and Free-Riding Behavior

    Directory of Open Access Journals (Sweden)

    Yongmei Liu

    2014-01-01

    Full Text Available Under dual-channel structure, the free-riding behavior based on different service levels between online channel and offline channel cannot be avoided, which would lead to channel unfairness. This study implies that the dual-channel supply chain is built up by online channel controlled by manufacturer and traditional channel controlled by retailer, respectively. Under this channel structure, we rebuild the linear demand function considering free-riding behavior and modify the pricing model based on channel fairness. Then the influences of fair factor and free-riding behavior on manufacturer and retailer pricing and performance are discussed. Finally, we propose some numerical analysis to provide some valuable recommendations for manufacturer and retailer improving channel management performance.

  5. Osmosis and pervaporation in polyimide submicron microfluidic channel structures

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Bomer, Johan G.; van den Berg, Albert

    2005-01-01

    Osmosis and pervaporation of water through the roof of all-polyimide channels of 500 nm height is described. The phenomena cause both a liquid flow in the channels and a concentration change of dissolved salt. Both effects are amplified due to the thin channel roof and the small channel height.

  6. An 8-Channel Wavelength MMI Demultiplexer in Slot Waveguide Structures

    Directory of Open Access Journals (Sweden)

    Bar Baruch Ben Zaken

    2016-11-01

    Full Text Available We propose a novel 8-channel wavelength multimode interference (MMI demultiplexer in slot waveguide structures that operate at 1530 nm, 1535 nm, 1540 nm, 1545 nm, 1550 nm, 1555 nm, 1560 nm, and 1565 nm. Gallium nitride (GaN surrounded by silicon (Si was found to be a suitable material for the slot-waveguide structures. The proposed device was designed by seven 1 × 2 MMI couplers, fourteen S-bands, and one input taper. Numerical investigations were carried out on the geometrical parameters using a full vectorial-beam propagation method (FV-BPM. Simulation results show that the proposed device can transmit 8-channel that works in the whole C-band (1530–1565 nm with low crosstalk (−19.97–−13.77 dB and bandwidth (1.8–3.6 nm. Thus, the device can be very useful in optical networking systems that work on dense wavelength division multiplexing (DWDM technology.

  7. Permeation and dynamics of an open-activated TRPV1 channel.

    Science.gov (United States)

    Darré, Leonardo; Furini, Simone; Domene, Carmen

    2015-01-30

    Transient receptor potential (TRP) ion channels constitute a large and diverse protein family, found in yeast and widespread in the animal kingdom. TRP channels work as sensors for a wide range of cellular and environmental signals. Understanding how these channels respond to physical and chemical stimuli has been hindered by the limited structural information available until now. The three-dimensional structure of the vanilloid receptor 1 (TRPV1) was recently determined by single particle electron cryo-microscopy, offering for the first time the opportunity to explore ionic conduction in TRP channels at atomic detail. In this study, we present molecular dynamics simulations of the open-activated pore domain of TRPV1 in the presence of three cationic species: Na(+), Ca(2+) and K(+). The dynamics of these ions while interacting with the channel pore allowed us to rationalize their permeation mechanism in terms of a pathway involving three binding sites at the intracellular cavity, as well as the extracellular and intracellular entrance of the selectivity filter. Furthermore, conformational analysis of the pore in the presence of these ions reveals specific ion-mediated structural changes in the selectivity filter, which influences the permeability properties of the TRPV1 channel. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Highly stable thin film transistors using multilayer channel structure

    KAUST Repository

    Nayak, Pradipta K.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60°C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  9. Role of Ca++ Influx via Epidermal TRP Ion Channels

    Science.gov (United States)

    2017-12-01

    30 General Procedure for the nitro to aniline reduction: A solution of the nitro compound (0.5 M in MeOH) was cooled in an ice-NaCl bath. Zinc dust...as previously described in61. Control animals received 25% DMSO-saline solution by intraperitoneal injection every hour for 6 h. Compound 16-8 was...diluted 1/4–1/20 (in Mobile phase A, see below) and placed in autosampler for LC-MS/MS analysis. The LC-MS/MS assay for 16-… compounds and GSK205 was

  10. Role of Ca ++ Influx via Epidermal TRP Ion Channels

    Science.gov (United States)

    2016-10-01

    widely read forum on Pain Medicine in the US and in English-speaking countries. http://www.painmedicinenews.com/Science-Technology/Article/08-16/Study...University, Durham NC USA. 2Dept of Medicine , Duke University, Durham NC USA. 3Dept of Chemistry, Duke University, Durham NC USA. 4Dept of Neurobiology...TRPA1- antagonistic compound. Potent TRPV4/TRPA1 dual-inhibitor, 16-8, is effective at controlling inflammation and pain in acute pancreatitis. These

  11. Transient Receptor Potential Channels as Targets for Phytochemicals

    Science.gov (United States)

    2015-01-01

    To date, 28 mammalian transient receptor potential (TRP) channels have been cloned and characterized. They are grouped into six subfamilies on the basis of their amino acid sequence homology: TRP Ankyrin (TRPA), TRP Canonical (TRPC), TRP Melastatin (TRPM), TRP Mucolipin (TRPML), TRP Polycystin (TRPP), and TRP Vanilloid (TRPV). Most of the TRP channels are nonselective cation channels expressed on the cell membrane and exhibit variable permeability ratios for Ca2+ versus Na+. They mediate sensory functions (such as vision, nociception, taste transduction, temperature sensation, and pheromone signaling) and homeostatic functions (such as divalent cation flux, hormone release, and osmoregulation). Significant progress has been made in our understanding of the specific roles of these TRP channels and their activation mechanisms. In this Review, the emphasis will be on the activation of TRP channels by phytochemicals that are claimed to exert health benefits. Recent findings complement the anecdotal evidence that some of these phytochemicals have specific receptors and the activation of which is responsible for the physiological effects. Now, the targets for these phytochemicals are being unveiled; a specific hypothesis can be proposed and tested experimentally to infer a scientific validity of the claims of the health benefits. The broader and pressing issues that have to be addressed are related to the quantities of the active ingredients in a given preparation, their bioavailability, metabolism, adverse effects, excretion, and systemic versus local effects. PMID:24926802

  12. Crystal structure of the channelrhodopsin light-gated cation channel

    Science.gov (United States)

    Kato, Hideaki E.; Zhang, Feng; Yizhar, Ofer; Ramakrishnan, Charu; Nishizawa, Tomohiro; Hirata, Kunio; Ito, Jumpei; Aita, Yusuke; Tsukazaki, Tomoya; Hayashi, Shigehiko; Hegemann, Peter; Maturana, Andrés D.; Ishitani, Ryuichiro; Deisseroth, Karl; Nureki, Osamu

    2014-01-01

    Channelrhodopsins (ChRs) are light-gated cation channels derived from algae that have shown experimental utility in optogenetics; for example, neurons expressing ChRs can be optically controlled with high temporal precision within systems as complex as freely moving mammals. Although ChRs have been broadly applied to neuroscience research, little is known about the molecular mechanisms by which these unusual and powerful proteins operate. Here we present the crystal structure of a ChR (a C1C2 chimaera between ChR1 and ChR2 from Chlamydomonas reinhardtii) at 2.3 Å resolution. The structure reveals the essential molecular architecture of ChRs, including the retinal-binding pocket and cation conduction pathway. This integration of structural and electrophysiological analyses provides insight into the molecular basis for the remarkable function of ChRs, and paves the way for the precise and principled design of ChR variants with novel properties. PMID:22266941

  13. Channel Contract Behavior: the Role of Risk Attitudes, Risk Perceptions, and Channel Members' Market Structures

    NARCIS (Netherlands)

    Pennings, J.M.E.; Wansink, B.

    2004-01-01

    By integrating elements of both marketing and finance, we show how risk influences channel contract behavior. We model risk behavior as the interaction between risk attitude and risk perception (IRAP). An analysis of the joint channel decisions of 208 producers, wholesalers, and processors provides

  14. Interaction of a peptide derived from C-terminus of human TRPA1 channel with model membranes mimicking the inner leaflet of the plasma membrane

    Czech Academy of Sciences Publication Activity Database

    Witschas, Katja; Jobin, M.-L.; Korkut, D. N.; Vladan, M. M.; Salgado, G.; Lecomte, S.; Vlachová, Viktorie; Alves, I. D.

    2015-01-01

    Roč. 1848, č. 5 (2015), s. 1147-1159 ISSN 0005-2736 R&D Projects: GA MŠk(CZ) EE2.3.30.0025 Institutional support: RVO:67985823 Keywords : TRP channels * peptide-lipid intractions * secondary structure Subject RIV: ED - Physiology Impact factor: 3.687, year: 2015

  15. Guiding motor-propelled molecules with nanoscale precision through silanized bi-channel structures

    Science.gov (United States)

    Bunk, Richard; Sundberg, Mark; Månsson, Alf; Nicholls, Ian A.; Omling, Pär; Tågerud, Sven; Montelius, Lars

    2005-06-01

    We report on the design and fabrication of a channel structure for high precision guidance and achieving excellent confinement properties for motor-propelled molecular shuttles. The techniques used to manufacture the channel structure are mainly e-beam lithography and selective monolayer functionalization. The structure consists of two lateral layers of concentric channels on a SiO2 surface made biocompatible with the molecular motors. The quality and advantages of the design are demonstrated by experiments using the motor proteins actin and myosin. The special channel geometry leads to stable biochemical conditions with full motor protein functionality. ATP is sufficiently supplied to all parts of the structure by dedicated service channels, as is the venting of ADP and Pi (inorganic phosphorus). Channels of different widths (100-700 nm) and shapes are fabricated and measurements made on them.

  16. Biological Membrane Ion Channels Dynamics, Structure, and Applications

    CERN Document Server

    Chung, Shin-Ho; Krishnamurthy, Vikram

    2007-01-01

    Ion channels are biological nanotubes that are formed by membrane proteins. Because ion channels regulate all electrical activities in living cells, understanding their mechanisms at a molecular level is a fundamental problem in biology. This book deals with recent breakthroughs in ion-channel research that have been brought about by the combined effort of experimental biophysicists and computational physicists, who together are beginning to unravel the story of these exquisitely designed biomolecules. With chapters by leading experts, the book is aimed at researchers in nanodevices and biosensors, as well as advanced undergraduate and graduate students in biology and the physical sciences. Key Features Presents the latest information on the molecular mechanisms of ion permeation through membrane ion channels Uses schematic diagrams to illustrate important concepts in biophysics Written by leading researchers in the area of ion channel investigations

  17. Putative Structural and Functional Coupling of the Mitochondrial BKCa Channel to the Respiratory Chain.

    Directory of Open Access Journals (Sweden)

    Piotr Bednarczyk

    Full Text Available Potassium channels have been found in the inner mitochondrial membranes of various cells. These channels regulate the mitochondrial membrane potential, the matrix volume and respiration. The activation of these channels is cytoprotective. In our study, the single-channel activity of a large-conductance Ca(2+-regulated potassium channel (mitoBKCa channel was measured by patch-clamping mitoplasts isolated from the human astrocytoma (glioblastoma U-87 MG cell line. A potassium-selective current was recorded with a mean conductance of 290 pS in symmetrical 150 mM KCl solution. The channel was activated by Ca(2+ at micromolar concentrations and by the potassium channel opener NS1619. The channel was inhibited by paxilline and iberiotoxin, known inhibitors of BKCa channels. Western blot analysis, immuno-gold electron microscopy, high-resolution immunofluorescence assays and polymerase chain reaction demonstrated the presence of the BKCa channel β4 subunit in the inner mitochondrial membrane of the human astrocytoma cells. We showed that substrates of the respiratory chain, such as NADH, succinate, and glutamate/malate, decrease the activity of the channel at positive voltages. This effect was abolished by rotenone, antimycin and cyanide, inhibitors of the respiratory chain. The putative interaction of the β4 subunit of mitoBKCa with cytochrome c oxidase was demonstrated using blue native electrophoresis. Our findings indicate possible structural and functional coupling of the mitoBKCa channel with the mitochondrial respiratory chain in human astrocytoma U-87 MG cells.

  18. Spin transport in lateral structures with semiconducting channel

    Science.gov (United States)

    Zainuddin, Abu Naser

    Spintronics is an emerging field of electronics with the potential to be used in future integrated circuits. Spintronic devices are already making their mark in storage technologies in recent times and there are proposals for using spintronic effects in logic technologies as well. So far, major improvement in spintronic effects, for example, the `spin-valve' effect, is being achieved in metals or insulators as channel materials. But not much progress is made in semiconductors owing to the difficulty in injecting spins into them, which has only very recently been overcome with the combined efforts of many research groups around the world. The key motivations for semiconductor spintronics are their ease in integration with the existing semiconductor technology along with the gate controllability. At present semiconductor based spintronic devices are mostly lateral and are showing a very poor performance compared to their metal or insulator based vertical counterparts. The objective of this thesis is to analyze these devices based on spin-transport models and simulations. At first a lateral spin-valve device is modeled with the spin-diffusion equation based semiclassical approach. Identifying the important issues regarding the device performance, a compact circuit equivalent model is presented which would help to improve the device design. It is found that the regions outside the current path also have a significant influence on the device performance under certain conditions, which is ordinarily neglected when only charge transport is considered. Next, a modified spin-valve structure is studied where the spin signal is controlled with a gate in between the injecting and detecting contacts. The gate is used to modulate the rashba spin-orbit coupling of the channel which, in turn, modulates the spin-valve signal. The idea of gate controlled spin manipulation was originally proposed by Datta and Das back in 1990 and is called 'Datta-Das' effect. In this thesis, we have

  19. Structure-based assessment of disease-related mutations in human voltage-gated sodium channels

    Directory of Open Access Journals (Sweden)

    Weiyun Huang

    2017-02-01

    Full Text Available ABSTRACT Voltage-gated sodium (Nav channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Nav channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Nav channels, with Nav1.1 and Nav1.5 each harboring more than 400 mutations. Nav channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Nav channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Cav channel Cav1.1 provides a template for homology-based structural modeling of the evolutionarily related Nav channels. In this Resource article, we summarized all the reported disease-related mutations in human Nav channels, generated a homologous model of human Nav1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Nav channels, the analysis presented here serves as the base framework for mechanistic investigation of Nav channelopathies and for potential structure-based drug discovery.

  20. Cantu syndrome-associated SUR2 (ABCC9) mutations in distinct structural domains result in KATP channel gain-of-function by differential mechanisms.

    Science.gov (United States)

    McClenaghan, Conor; Hanson, Alex; Sala-Rabanal, Monica; Roessler, Helen I; Josifova, Dragana; Grange, Dorothy K; van Haaften, Gijs; Nichols, Colin G

    2018-02-09

    The complex disorder Cantu syndrome (CS) arises from gain-of-function mutations in either KCNJ8 or ABCC9 , the genes encoding the Kir6.1 and SUR2 subunits of ATP-sensitive potassium (K ATP ) channels, respectively. Recent reports indicate that such mutations can increase channel activity by multiple molecular mechanisms. In this study, we determined the mechanism by which K ATP function is altered by several substitutions in distinct structural domains of SUR2: D207E in the intracellular L0-linker and Y985S, G989E, M1060I, and R1154Q/R1154W in TMD2. We engineered substitutions at their equivalent positions in rat SUR2A (D207E, Y981S, G985E, M1056I, and R1150Q/R1150W) and investigated functional consequences using macroscopic rubidium ( 86 Rb + ) efflux assays and patch-clamp electrophysiology. Our results indicate that D207E increases K ATP channel activity by increasing intrinsic stability of the open state, whereas the cluster of Y981S/G985E/M1056I substitutions, as well as R1150Q/R1150W, augmented Mg-nucleotide activation. We also tested the responses of these channel variants to inhibition by the sulfonylurea drug glibenclamide, a potential pharmacotherapy for CS. None of the D207E, Y981S, G985E, or M1056I substitutions had a significant effect on glibenclamide sensitivity. However, Gln and Trp substitution at Arg-1150 significantly decreased glibenclamide potency. In summary, these results provide additional confirmation that mutations in CS-associated SUR2 mutations result in K ATP gain-of-function. They help link CS genotypes to phenotypes and shed light on the underlying molecular mechanisms, including consequences for inhibitory drug sensitivity, insights that may inform the development of therapeutic approaches to manage CS. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Online channel operation mode: Game theoretical analysis from the supply chain power structure

    Directory of Open Access Journals (Sweden)

    Song Huang

    2015-11-01

    Full Text Available Purpose: Dual-channels have been widely used in practice, and the pricing decisions and the online channel operation mode choice have been the core problems in dual-channel supply chain management. This paper focuses on the online channel operation mode choice from the supply chain power structures based on game theoretical analysis. Design/methodology/approach: This paper utilizes three kinds of game theoretical models to analyze the impact of supply chain power structures on the optimal pricing and online channel operation mode choice. Findings: Results derived in this paper indicate that when the self-price elasticity is large, the power structures have no direct impact on the decisions. However, when the self-price elasticity is small and customers’ preference for the online channel is low, then in the MS market, it is better for the retailer to operate the online channel, while in the RS market or in the VN market, it is better for the manufacturer to operate the online channel. Research limitations/implications: In this paper, we do not consider stochastic demand and asymmetric information, which may not well suit the reality. Originality/value: This paper provides a different perspective to analyze the impact of supply chain power structures on the pricing decisions and online channel operation mode choice. The comparison of these two online channel operation modes in this paper is also a unique point.

  2. Structure and mechanical properties of aluminum alloy 6061 subjected to equal-channel angular pressing in parallel channels

    Science.gov (United States)

    Murashkin, M. Yu.; Bobruk, E. V.; Kil'Mametov, A. R.; Valiev, R. Z.

    2009-10-01

    It is shown that a uniform ultrafine-grained structure in alloy 6061 can be formed already after four cycles of treatment by equal-channel angular pressing in parallel channels (ECAP-PC). Along with grain refinement, in the process of an ECAP-PC treatment there occurs in the alloy a dynamic strain aging, which results in the formation of nanodimensional particles of a strengthening phase Mg2Si. It has been established that the alloy in the UFG state demonstrates a considerably higher level of strength and better plasticity in comparison with the material after a standard strengthening treatment.

  3. Eukaryotic Catalase-Peroxidase: The Role of the Trp-Tyr-Met Adduct in Protein Stability, Substrate Accessibility, and Catalysis of Hydrogen Peroxide Dismutation.

    Science.gov (United States)

    Gasselhuber, Bernhard; Carpena, Xavi; Graf, Michael M H; Pirker, Katharina F; Nicolussi, Andrea; Sündermann, Axel; Hofbauer, Stefan; Zamocky, Marcel; Furtmüller, Paul G; Jakopitsch, Christa; Oostenbrink, Chris; Fita, Ignacio; Obinger, Christian

    2015-09-08

    Recently, it was demonstrated that bifunctional catalase-peroxidases (KatGs) are found not only in archaea and bacteria but also in lower eukaryotes. Structural studies and preliminary biochemical data of the secreted KatG from the rice pathogen Magnaporthe grisea (MagKatG2) suggested both similar and novel features when compared to those of the prokaryotic counterparts studied so far. In this work, we demonstrate the role of the autocatalytically formed redox-active Trp140-Tyr273-Met299 adduct of MagKatG2 in (i) the maintenance of the active site architecture, (ii) the catalysis of hydrogen peroxide dismutation, and (iii) the protein stability by comparing wild-type MagKatG2 with the single mutants Trp140Phe, Tyr273Phe, and Met299Ala. The impact of disruption of the covalent bonds between the adduct residues on the spectral signatures and heme cavity architecture was small. By contrast, loss of its integrity converts bifunctional MagKatG2 to a monofunctional peroxidase of significantly reduced thermal stability. It increases the accessibility of ligands due to the increased flexibility of the KatG-typical large loop 1 (LL1), which contributes to the substrate access channel and anchors at the adduct Tyr. We discuss these data with respect to those known from prokaryotic KatGs and in addition present a high-resolution structure of an oxoiron compound of MagKatG2.

  4. Burst pressure of phaseguide structures of different heights in all-polymer microfluidic channels

    DEFF Research Database (Denmark)

    Garbarino, Francesca; Kistrup, Kasper; Rizzi, Giovanni

    2017-01-01

    We present an experimental investigation of the burst/overflow pressure of water and a representative surfactant-containing buffer in microfluidic channels with phaseguide structures oriented at an angle of 90° to the channel length as a function of their height, . The all-polymer chips were fabr...

  5. Insights of adsorption mechanisms of Trp-peptides on plasmonic surfaces by SERS

    Science.gov (United States)

    daFonseca, Bruno Guilherme; Costa, Luiz Antônio Sodré; Sant'Ana, Antonio Carlos

    2018-02-01

    The adsorptions of tryptophan (Trp) on silver or gold surfaces were investigated by surface-enhanced Raman scattering (SERS) measurements. In addition, peptides with Trp in different chain positions were studied and the adsorption sites were determined based on marker bands. The indole ring was the main group responsible for the interactions with gold nanoparticles (AuNPs). In the presence of HCl, the SERS spectra suggested that the anchoring of such peptides on AuNPs was reinforced by ionic pair interactions between protonated amine and chloride ions. The adsorptions of Trp and its derivatives on silver nanoparticles (AgNPs) show some variability in the spectral patterns, even though the enhanced carboxilate and amino features were ever ascribed as preferable adsorption site. Based on DFT calculations the vibrational assignment allows the reinterpretation of previous published works. The investigations showed that both the high affinity of indole moiety for the AuNP surfaces make these substrates adequate for studying the adsorption of peptides containing Trp and the proposed SERS assignments could be helpful for further studies of more complex structures.

  6. Structure of functional Staphylococcus aureus alpha-hemolysin channels in tethered bilayer lipid membranes.

    Science.gov (United States)

    McGillivray, Duncan J; Valincius, Gintaras; Heinrich, Frank; Robertson, Joseph W F; Vanderah, David J; Febo-Ayala, Wilma; Ignatjev, Ilja; Lösche, Mathias; Kasianowicz, John J

    2009-02-18

    We demonstrate a method for simultaneous structure and function determination of integral membrane proteins. Electrical impedance spectroscopy shows that Staphylococcus aureus alpha-hemolysin channels in membranes tethered to gold have the same properties as those formed in free-standing bilayer lipid membranes. Neutron reflectometry provides high-resolution structural information on the interaction between the channel and the disordered membrane, validating predictions based on the channel's x-ray crystal structure. The robust nature of the membrane enabled the precise localization of the protein within 1.1 A. The channel's extramembranous cap domain affects the lipid headgroup region and the alkyl chains in the outer membrane leaflet and significantly dehydrates the headgroups. The results suggest that this technique could be used to elucidate molecular details of the association of other proteins with membranes and may provide structural information on domain organization and stimuli-responsive reorganization for transmembrane proteins in membrane mimics.

  7. Krebs cycle metabolon: structural evidence of substrate channeling revealed by cross-linking and mass spectrometry.

    Science.gov (United States)

    Wu, Fei; Minteer, Shelley

    2015-02-02

    It has been hypothesized that the high metabolic flux in the mitochondria is due to the self-assembly of enzyme supercomplexes (called metabolons) that channel substrates from one enzyme to another, but there has been no experimental confirmation of this structure or the channeling. A structural investigation of enzyme organization within the Krebs cycle metabolon was accomplished by in vivo cross-linking and mass spectrometry. Eight Krebs cycle enzyme components were isolated upon chemical fixation, and interfacial residues between mitochondrial malate dehydrogenase, citrate synthase, and aconitase were identified. Using constraint protein docking, a low-resolution structure for the three-enzyme complex was achieved, as well as the two-fold symmetric octamer. Surface analysis showed formation of electrostatic channeling upon protein-protein association, which is the first structural evidence of substrate channeling in the Krebs cycle metabolon. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Structural insights into the voltage and phospholipid activation of the mammalian TPC1 channel.

    Science.gov (United States)

    She, Ji; Guo, Jiangtao; Chen, Qingfeng; Zeng, Weizhong; Jiang, Youxing; Bai, Xiao-Chen

    2018-03-21

    The organellar two-pore channel (TPC) functions as a homodimer, in which each subunit contains two homologous Shaker-like six-transmembrane (6-TM)-domain repeats. TPCs belong to the voltage-gated ion channel superfamily and are ubiquitously expressed in animals and plants. Mammalian TPC1 and TPC2 are localized at the endolysosomal membrane, and have critical roles in regulating the physiological functions of these acidic organelles. Here we present electron cryo-microscopy structures of mouse TPC1 (MmTPC1)-a voltage-dependent, phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P 2 )-activated Na + -selective channel-in both the apo closed state and ligand-bound open state. Combined with functional analysis, these structures provide comprehensive structural insights into the selectivity and gating mechanisms of mammalian TPC channels. The channel has a coin-slot-shaped ion pathway in the filter that defines the selectivity of mammalian TPCs. Only the voltage-sensing domain from the second 6-TM domain confers voltage dependence on MmTPC1. Endolysosome-specific PtdIns(3,5)P 2 binds to the first 6-TM domain and activates the channel under conditions of depolarizing membrane potential. Structural comparisons between the apo and PtdIns(3,5)P 2 -bound structures show the interplay between voltage and ligand in channel activation. These MmTPC1 structures reveal lipid binding and regulation in a 6-TM voltage-gated channel, which is of interest in light of the emerging recognition of the importance of phosphoinositide regulation of ion channels.

  9. Spatial Diversity in Composition and Structure of Nekton in Ngenep Spring and its Channels, Karangploso - Malang

    Directory of Open Access Journals (Sweden)

    Lia Hapsari

    2014-04-01

    Full Text Available Water springs and its channel degradation due to anthropogenic pollution may alter the community structure of aquatic organisms. Water spring degradation tehrefore affect the quality of water as tourism resources. This study aims to investigate the changes in community structure of nekton  and determine the relationships between water quality characteristics to the diversity of nekton.  The field survey was set up in Ngenep spring and its channels. Results showed that nekton species found in Ngenep spring and its channels consists of 4 classes, 4 orders, 6 families, and 7 species with total 627 nekton samples. It is comprises of fishes, shrimp, frogs and waterstriders. Nekton diversity index (H’ in the spring and irrigation channel were in moderate level (1channel was low (0,67. Evenness values of nekton ranged 0,24 – 0,53, whereas dominancy index of nekton ranged 0,41 – 0,74. Evenness value in settlement channel was very low (0, 24 with high dominancy index (0, 74; it indicates that nekton species were spread not evenly in the channel, it dominated by fish Rasbora sp. (highest IVI, 184,95. There were spatial variations of  physico-chemical water qualitiy parameters in Ngenep springs and its channels (temperature, stream velocity, turbidity, conductivity, pH, DO, BOD and TOM which affected to nekton diversity and community structure. Clustering analyses and PCA result shows correlation pattern between nekton distribution with physico-chemical water quality parameters. However, physico-chemical water quality parameters in Ngenep springs and its channel were still optimum as nekton habitat (PP No. 82/ 2001. Keywords: Community structure, Nekton, Spatial diversity, Spring, Water channel

  10. Direct visualization of the trimeric structure of the ASIC1a channel, using AFM imaging

    International Nuclear Information System (INIS)

    Carnally, Stewart M.; Dev, Harveer S.; Stewart, Andrew P.; Barrera, Nelson P.; Van Bemmelen, Miguel X.; Schild, Laurent; Henderson, Robert M.; Edwardson, J.Michael

    2008-01-01

    There has been confusion about the subunit stoichiometry of the degenerin family of ion channels. Recently, a crystal structure of acid-sensing ion channel (ASIC) 1a revealed that it assembles as a trimer. Here, we used atomic force microscopy (AFM) to image unprocessed ASIC1a bound to mica. We detected a mixture of subunit monomers, dimers and trimers. In some cases, triple-subunit clusters were clearly visible, confirming the trimeric structure of the channel, and indicating that the trimer sometimes disaggregated after adhesion to the mica surface. This AFM-based technique will now enable us to determine the subunit arrangement within heteromeric ASICs

  11. Dependency plots suggest the kinetic structure of ion channels.

    Science.gov (United States)

    Magleby, K L; Song, L

    1992-08-22

    Ion channels are integral membrane proteins that regulate ionic flux through cell membranes by opening and closing (gating) their pores. The gating can be monitored by observing step changes in the current flowing through single channels, and analysis of the observed open and closed interval durations has provided a window to develop kinetic models for the gating process. One difficulty in developing such models has been to determine the connections (transition pathways) among the various kinetic states involved in the gating. To help overcome this difficulty we present a transform (dependency plot) of the single-channel data that can give immediate insight into the connections. A dependency plot is derived by calculating a contingency table from a two-dimensional (joint density) dwell-time distribution of adjacent open and closed intervals by assuming that the two classified criteria are the open and closed durations of each pair of adjacent intervals. A three-dimensional surface plot of the fractional difference between the numbers of observed interval pairs and the numbers expected if the durations of adjacent intervals are independent then gives the dependency plot. An excess of interval pairs in the dependency plot suggests that the open and closed states (or compound states) that give rise to the interval pairs in excess are directly connected. A deficit of interval pairs suggests that the open and closed states (or compound states) that give rise to the interval pairs in deficit are either not directly connected or that there are additional open-closed transition pathways arising from the directly connected states.

  12. Improved vertical MOSFET performance using an epitaxial channel and a stacked silicon-insulator structure

    International Nuclear Information System (INIS)

    Uchino, T; Gili, E; Ashburn, P; Tan, L; Buiu, O; Hall, S

    2012-01-01

    A vertical MOSFET (VMOST) incorporating an epitaxial channel and a drain junction in a stacked silicon-insulator structure is presented. In this device structure, an oxide layer near the drain junction edge (referred to as a junction stop) acts as a dopant diffusion barrier and consequently a shallow drain junction is formed to suppress short channel effects. To investigate the scalability of this device, a simulation study in the sub-100 nm regime calibrated to measured results on the fabricated devices is carried out. The use of an epitaxial channel delivers 50% higher drive current due to the higher mobility of the retrograde channel and the junction stop structure delivers improvements of threshold voltage roll-off and drain-induced barrier lowering compared with a conventional VMOST. (fast track communication)

  13. Computational Structural Pharmacology and Toxicology of Voltage-Gated Sodium Channels.

    Science.gov (United States)

    Zhorov, B S; Tikhonov, D B

    2016-01-01

    Voltage-gated sodium channels are targets for many toxins and medically important drugs. Despite decades of intensive studies in industry and academia, atomic mechanisms of action are still not completely understood. The major cause is a lack of high-resolution structures of eukaryotic channels and their complexes with ligands. In these circumstances a useful approach is homology modeling that employs as templates X-ray structures of potassium channels and prokaryotic sodium channels. On one hand, due to inherent limitations of this approach, results should be treated with caution. In particular, models should be tested against relevant experimental data. On the other hand, docking of drugs and toxins in homology models provides a unique possibility to integrate diverse experimental data provided by mutational analysis, electrophysiology, and studies of structure-activity relations. Here we describe how homology modeling advanced our understanding of mechanisms of several classes of ligands. These include tetrodotoxins and mu-conotoxins that block the outer pore, local anesthetics that block of the inner pore, batrachotoxin that binds in the inner pore but, paradoxically, activates the channel, pyrethroid insecticides that activate the channel by binding at lipid-exposed repeat interfaces, and scorpion alpha and beta-toxins, which bind between the pore and voltage-sensing domains and modify the channel gating. We emphasize importance of experimental data for elaborating the models. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Transit safety retrofit package development : TRP concept of operations.

    Science.gov (United States)

    2014-05-01

    This document describes the Concept of Operations (ConOps) for the Transit Safety Retrofit Package (TRP). The : ConOps describes the current state of operations with respect to the integration of Connected Vehicle technology in : transit buses, estab...

  15. Probing Ion Channel Structure and Function Using Light-Sensitive Amino Acids.

    Science.gov (United States)

    Klippenstein, Viktoria; Mony, Laetitia; Paoletti, Pierre

    2018-04-10

    Approaches to remotely control and monitor ion channel operation with light are expanding rapidly in the biophysics and neuroscience fields. A recent development directly introduces light sensitivity into proteins by utilizing photosensitive unnatural amino acids (UAAs) incorporated using the genetic code expansion technique. The introduction of UAAs results in unique molecular level control and, when combined with the maximal spatiotemporal resolution and poor invasiveness of light, enables direct manipulation and interrogation of ion channel functionality. Here, we review the diverse applications of light-sensitive UAAs in two superfamilies of ion channels (voltage- and ligand-gated ion channels; VGICs and LGICs) and summarize existing UAA tools, their mode of action, potential, caveats, and technical considerations to their use in illuminating ion channel structure and function. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Structure, function, and pharmacology of NMDA receptor channels

    Czech Academy of Sciences Publication Activity Database

    Vyklický, Vojtěch; Kořínek, Miloslav; Smejkalová, Tereza; Balík, Aleš; Krausová, Barbora; Kaniaková, Martina; Lichnerová, Katarina; Černý, Jiří; Krůšek, Jan; Dittert, Ivan; Horák, Martin; Vyklický ml., Ladislav

    2014-01-01

    Roč. 63, Suppl.1 (2014), S191-S203 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GAP303/11/0075; GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GAP303/12/1464; GA ČR(CZ) GPP303/11/P391; GA TA ČR(CZ) TE01020028; GA MŠk(CZ) EE2.3.30.0025; GA MŠk(CZ) ED1.1.00/02.0109 EU Projects: European Commission(XE) SalmandNmda 276827 Grant - others:Univerzita Karlova(CZ) 800313 Program:FP7 Institutional support: RVO:67985823 Keywords : glutamate receptor * NMDA receptor * ion Channel Subject RIV: ED - Physiology Impact factor: 1.293, year: 2014

  17. Transient receptor potential channels in mechanosensing and cell volume regulation

    DEFF Research Database (Denmark)

    Pedersen, Stine Falsig; Nilius, Bernd

    2007-01-01

    channels, and it is becoming increasingly apparent that Ca(2+) influx via TRP channels plays a crucial role in the response to mechanical and osmotic perturbations in a wide range of cell types. Although the events translating mechanical and osmotic stimuli into regulation of TRP channels are still...... incompletely understood, the specific mechanisms employed vary between different TRP isoforms, and probably include changes in the tension and/or curvature of the lipid bilayer, changes in the cortical cytoskeleton, and signaling events such as lipid metabolism and protein phosphorylation...... and involvement in cell volume regulation....

  18. Tensor based structure estimation in multi-channel images

    DEFF Research Database (Denmark)

    Schou, Jesper; Dierking, Wolfgang; Skriver, Henning

    2000-01-01

    . In the second part tensors are used for representing the structure information. This approach has the advantage, that tensors can be averaged either spatially or by applying several images, and the resulting tensor provides information of the average strength as well as orientation of the structure...

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

    Science.gov (United States)

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

    2001-12-01

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

  20. Development of NUPREP PC Version and Input Structures for NUCIRC Single Channel Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Churl; Jun, Ji Su; Park, Joo Hwan

    2007-12-15

    The input file for a steady-state thermal-hydraulic code NUCIRC consists of common channel input data and specific channel input data in a case of single channel analysis. Even when all the data is ready for the 380 channels' single channel analyses, it takes long time and requires enormous effort to compose an input file by hand-editing. The automatic pre-processor for this tedious job is a NUPREP code. In this study, a NUPREP PC version has been developed from the source list in the program manual of NUCIRC-MOD2.000 that is imported in a form of an execution file. In this procedure, some errors found in PC executions and lost statements are fixed accordingly. It is confirmed that the developed NUPREP code produces input file correctly for the CANDU-6 single channel analysis. Additionally, the NUCIRC input structure and data format are summarized for a single channel analysis and the input CARDs required for the creep information of aged channels are listed.

  1. Development of NUPREP PC Version and Input Structures for NUCIRC Single Channel Analyses

    International Nuclear Information System (INIS)

    Yoon, Churl; Jun, Ji Su; Park, Joo Hwan

    2007-12-01

    The input file for a steady-state thermal-hydraulic code NUCIRC consists of common channel input data and specific channel input data in a case of single channel analysis. Even when all the data is ready for the 380 channels' single channel analyses, it takes long time and requires enormous effort to compose an input file by hand-editing. The automatic pre-processor for this tedious job is a NUPREP code. In this study, a NUPREP PC version has been developed from the source list in the program manual of NUCIRC-MOD2.000 that is imported in a form of an execution file. In this procedure, some errors found in PC executions and lost statements are fixed accordingly. It is confirmed that the developed NUPREP code produces input file correctly for the CANDU-6 single channel analysis. Additionally, the NUCIRC input structure and data format are summarized for a single channel analysis and the input CARDs required for the creep information of aged channels are listed

  2. Structure of synaptophysin: a hexameric MARVEL-domain channel protein.

    Science.gov (United States)

    Arthur, Christopher P; Stowell, Michael H B

    2007-06-01

    Synaptophysin I (SypI) is an archetypal member of the MARVEL-domain family of integral membrane proteins and one of the first synaptic vesicle proteins to be identified and cloned. Most all MARVEL-domain proteins are involved in membrane apposition and vesicle-trafficking events, but their precise role in these processes is unclear. We have purified mammalian SypI and determined its three-dimensional (3D) structure by using electron microscopy and single-particle 3D reconstruction. The hexameric structure resembles an open basket with a large pore and tenuous interactions within the cytosolic domain. The structure suggests a model for Synaptophysin's role in fusion and recycling that is regulated by known interactions with the SNARE machinery. This 3D structure of a MARVEL-domain protein provides a structural foundation for understanding the role of these important proteins in a variety of biological processes.

  3. Covariance-based Spatial Channel Structure Emulation for MIMO OTA Testing

    DEFF Research Database (Denmark)

    Tsakalaki, Elpiniki; Alrabadi, Osama; Fan, Wei

    2014-01-01

    The paper presents a general framework for recreating the spatial channel structure in a MIMO over-the-air (OTA) multiprobe anechoic chamber testing setup. The idea is to find the power weights of the spatial taps (antenna probes) that minimize a certain distance between the spatial channel covar...... among the antennas-under-test by considering the whole spatial covariance structure. The simulation results validate the improved performance of the suggested approach in terms of emulation accuracy compared to the key emulation methods proposed in the literature....... covariance matrix corresponding to the desired (continuous) channel and the covariance related to the emulated (discrete) channel within the test area. Unlike previous methods that merely rely on the spatial correlation coefficient, the proposed approach properly accounts for emulating the power imbalance...

  4. Secure Degrees of Freedom Regions of Multiple Access and Interference Channels: The Polytope Structure

    OpenAIRE

    Xie, Jianwei; Ulukus, Sennur

    2014-01-01

    The sum secure degrees of freedom (s.d.o.f.) of two fundamental multi-user network structures, the K-user Gaussian multiple access (MAC) wiretap channel and the K-user interference channel (IC) with secrecy constraints, have been determined recently as K(K-1)/(K(K-1)+1) [1,2] and K(K-1)/(2K-1) [3,4], respectively. In this paper, we determine the entire s.d.o.f. regions of these two channel models. The converse for the MAC follows from a middle step in the converse of [1,2]. The converse for t...

  5. Dynamic Phenylalanine Clamp Interactions Define Single-Channel Polypeptide Translocation through the Anthrax Toxin Protective Antigen Channel.

    Science.gov (United States)

    Ghosal, Koyel; Colby, Jennifer M; Das, Debasis; Joy, Stephen T; Arora, Paramjit S; Krantz, Bryan A

    2017-03-24

    Anthrax toxin is an intracellularly acting toxin where sufficient detail is known about the structure of its channel, allowing for molecular investigations of translocation. The toxin is composed of three proteins, protective antigen (PA), lethal factor (LF), and edema factor (EF). The toxin's translocon, PA, translocates the large enzymes, LF and EF, across the endosomal membrane into the host cell's cytosol. Polypeptide clamps located throughout the PA channel catalyze the translocation of LF and EF. Here, we show that the central peptide clamp, the ϕ clamp, is a dynamic site that governs the overall peptide translocation pathway. Single-channel translocations of a 10-residue, guest-host peptide revealed that there were four states when peptide interacted with the channel. Two of the states had intermediate conductances of 10% and 50% of full conductance. With aromatic guest-host peptides, the 50% conducting intermediate oscillated with the fully blocked state. A Trp guest-host peptide was studied by manipulating its stereochemistry and prenucleating helix formation with a covalent linkage in the place of a hydrogen bond or hydrogen-bond surrogate (HBS). The Trp peptide synthesized with ʟ-amino acids translocated more efficiently than peptides synthesized with D- or alternating D,ʟ-amino acids. HBS stapled Trp peptide exhibited signs of steric hindrance and difficulty translocating. However, when mutant ϕ clamp (F427A) channels were tested, the HBS peptide translocated normally. Overall, peptide translocation is defined by dynamic interactions between the peptide and ϕ clamp. These dynamics require conformational flexibility, such that the peptide productively forms both extended-chain and helical states during translocation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Numerical, field and laboratory studies of three-dimensional flow structures at river channel confluences

    OpenAIRE

    Bradbrook, Kathryn Frances

    1999-01-01

    This thesis investigates controls on and the nature of three-dimensional flow structures at river channel confluences. Previous work has shown that junction angle is an important control on the flow patterns at channel junctions since it affects the degree of curvature of flow from each tributary and sets up secondary circulation cells similar to those in meander bends. Recent work has highlighted the common occurrence of, and importance of, bed discordance at river confluences due to a signi...

  7. Insight into DEG/ENaC channel gating from genetics and structure.

    Science.gov (United States)

    Eastwood, Amy L; Goodman, Miriam B

    2012-10-01

    The founding members of the superfamily of DEG/ENaC ion channel proteins are C. elegans proteins that form mechanosensitive channels in touch and pain receptors. For more than a decade, the research community has used mutagenesis to identify motifs that regulate gating. This review integrates insight derived from unbiased in vivo mutagenesis screens with recent crystal structures to develop new models for activation of mechanically gated DEGs.

  8. Comparison of experimental tests and theory for a rectangular two-channel dielectric wakefield accelerator structure

    Directory of Open Access Journals (Sweden)

    S. V. Shchelkunov

    2012-03-01

    Full Text Available Experimental results are reported for test beam acceleration and deflection in a two-channel, cm-scale, rectangular dielectric-lined wakefield accelerator structure energized by a 14-MeV drive beam. The dominant waveguide mode of the structure is at ∼30  GHz, and the structure is configured to exhibit a high transformer ratio (∼12∶1. Accelerated bunches in the narrow secondary channel of the structure are continuously energized via Cherenkov radiation that is emitted by a drive bunch moving in the wider primary channel. Observed energy gains and losses, transverse deflections, and changes in the test bunch charge distribution compare favorably with predictions of theory.

  9. Mathematical modeling of fluid flow in complex multi-channel structures

    Science.gov (United States)

    Shashkin, V. Y.

    2017-10-01

    The work is focused on a numerical hydraulic model, which allows one to simulate fluid flow in a complex, arbitrarily configured multi-channel system with a capability of automatic visualization of its structure. The main elements of a system are channels which are united in the system by means of a particular set of coupling elements (local resistance, knots). The processes models in channels are based on the equation of continuity, momentum conservation. The system structure is made by forming matrices of regional and internal boundary conditions according to the developed algorithm. By the model the algorithm is created, on the basis of which the application program is developed. The application program enables one to determine parameters of a steady state of fluid flow in the complex multichannel structures. The calculation structure is shown.

  10. Imaging and structural studies of DNA–protein complexes and membrane ion channels

    KAUST Repository

    Marini, Monica

    2017-01-17

    In bio-imaging by electron microscopy, damage of the sample and limited contrast are the two main hurdles for reaching high image quality. We extend a new preparation method based on nanofabrication and super-hydrophobicity to the imaging and structural studies of nucleic acids, nucleic acid-protein complexes (DNA/Rad51 repair protein complex) and neuronal ion channels (gap-junction, K+ and GABA(A) channels) as paradigms of biological significance and increasing complexity. The preparation method is based on the liquid phase and is compatible with physiological conditions. Only in the very last stage, samples are dried for TEM analysis. Conventional TEM and high-resolution TEM (HRTEM) were used to achieve a resolution of 3.3 and 1.5 angstrom, respectively. The EM dataset quality allows the determination of relevant structural and metrological information on the DNA structure, DNA-protein interactions and ion channels, allowing the identification of specific macromolecules and their structure.

  11. Molecular Determinants of Phosphatidylinositol 4,5-Bisphosphate (PI(4,5)P2) Binding to Transient Receptor Potential V1 (TRPV1) Channels*

    Science.gov (United States)

    Poblete, Horacio; Oyarzún, Ingrid; Olivero, Pablo; Comer, Jeffrey; Zuñiga, Matías; Sepulveda, Romina V.; Báez-Nieto, David; González Leon, Carlos; González-Nilo, Fernando; Latorre, Ramón

    2015-01-01

    Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) has been recognized as an important activator of certain transient receptor potential (TRP) channels. More specifically, TRPV1 is a pain receptor activated by a wide range of stimuli. However, whether or not PI(4,5)P2 is a TRPV1 agonist remains open to debate. Utilizing a combined approach of mutagenesis and molecular modeling, we identified a PI(4,5)P2 binding site located between the TRP box and the S4-S5 linker. At this site, PI(4,5)P2 interacts with the amino acid residues Arg-575 and Arg-579 in the S4-S5 linker and with Lys-694 in the TRP box. We confirmed that PI(4,5)P2 behaves as a channel agonist and found that Arg-575, Arg-579, and Lys-694 mutations to alanine reduce PI(4,5)P2 binding affinity. Additionally, in silico mutations R575A, R579A, and K694A showed that the reduction in binding affinity results from the delocalization of PI(4,5)P2 in the binding pocket. Molecular dynamics simulations indicate that PI(4,5)P2 binding induces conformational rearrangements of the structure formed by S6 and the TRP domain, which cause an opening of the lower TRPV1 channel gate. PMID:25425643

  12. Is TrpM5 a reliable marker for chemosensory cells? Multiple types of microvillous cells in the main olfactory epithelium of mice

    Directory of Open Access Journals (Sweden)

    Finger Thomas E

    2008-12-01

    Full Text Available Abstract Background In the past, ciliated receptor neurons, basal cells, and supporting cells were considered the principal components of the main olfactory epithelium. Several studies reported the presence of microvillous cells but their function is unknown. A recent report showed cells in the main olfactory epithelium that express the transient receptor potential channel TrpM5 claiming that these cells are chemosensory and that TrpM5 is an intrinsic signaling component of mammalian chemosensory organs. We asked whether the TrpM5-positive cells in the olfactory epithelium are microvillous and whether they belong to a chemosensory system, i.e. are olfactory neurons or trigeminally-innervated solitary chemosensory cells. Results We investigated the main olfactory epithelium of mice at the light and electron microscopic level and describe several subpopulations of microvillous cells. The ultrastructure of the microvillous cells reveals at least three morphologically different types two of which express the TrpM5 channel. None of these cells have an axon that projects to the olfactory bulb. Tests with a large panel of cell markers indicate that the TrpM5-positive cells are not sensory since they express neither neuronal markers nor are contacted by trigeminal nerve fibers. Conclusion We conclude that TrpM5 is not a reliable marker for chemosensory cells. The TrpM5-positive cells of the olfactory epithelium are microvillous and may be chemoresponsive albeit not part of the sensory apparatus. Activity of these microvillous cells may however influence functionality of local elements of the olfactory system.

  13. Is TrpM5 a reliable marker for chemosensory cells? Multiple types of microvillous cells in the main olfactory epithelium of mice.

    Science.gov (United States)

    Hansen, Anne; Finger, Thomas E

    2008-12-04

    In the past, ciliated receptor neurons, basal cells, and supporting cells were considered the principal components of the main olfactory epithelium. Several studies reported the presence of microvillous cells but their function is unknown. A recent report showed cells in the main olfactory epithelium that express the transient receptor potential channel TrpM5 claiming that these cells are chemosensory and that TrpM5 is an intrinsic signaling component of mammalian chemosensory organs. We asked whether the TrpM5-positive cells in the olfactory epithelium are microvillous and whether they belong to a chemosensory system, i.e. are olfactory neurons or trigeminally-innervated solitary chemosensory cells. We investigated the main olfactory epithelium of mice at the light and electron microscopic level and describe several subpopulations of microvillous cells. The ultrastructure of the microvillous cells reveals at least three morphologically different types two of which express the TrpM5 channel. None of these cells have an axon that projects to the olfactory bulb. Tests with a large panel of cell markers indicate that the TrpM5-positive cells are not sensory since they express neither neuronal markers nor are contacted by trigeminal nerve fibers. We conclude that TrpM5 is not a reliable marker for chemosensory cells. The TrpM5-positive cells of the olfactory epithelium are microvillous and may be chemoresponsive albeit not part of the sensory apparatus. Activity of these microvillous cells may however influence functionality of local elements of the olfactory system.

  14. TRPM5 is a transient Ca2+-activated cation channel responding to rapid changes in [Ca2+]i

    OpenAIRE

    Prawitt, Dirk; Monteilh-Zoller, Mahealani K.; Brixel, Lili; Spangenberg, Christian; Zabel, Bernhard; Fleig, Andrea; Penner, Reinhold

    2003-01-01

    Transient receptor potential (TRP) proteins are a diverse family of proteins with structural features typical of ion channels. TRPM5, a member of the TRPM subfamily, plays an important role in taste receptors, although its activation mechanism remains controversial and its function in signal transduction is unknown. Here we characterize the functional properties of heterologously expressed human TRPM5 in HEK-293 cells. TRPM5 displays characteristics of a calcium-activated, nonselective cation...

  15. TRP iontové kanály: molekulární senzory v nervové soustavě

    Czech Academy of Sciences Publication Activity Database

    Benedikt, Jan; Vyklický st., Ladislav; Toušová, Karolina; Vlachová, Viktorie

    2005-01-01

    Roč. 9, Suppl. 3 (2005), s. 6-11 ISSN 1211-7579 R&D Projects: GA ČR(CZ) GA305/03/0802; GA MŠk(CZ) LC554; GA MŠk(CZ) 1M0517 Institutional research plan: CEZ:AV0Z50110509 Keywords : TRP channels * nociception * vanilloid receptor Subject RIV: ED - Physiology

  16. Ni2+ binds to active site of hen egg-white lysozyme and quenches fluorescence of Trp62 and Trp108

    International Nuclear Information System (INIS)

    Li Shujie; Nakagawa, Atsushi; Tsukihara, Tomitake

    2004-01-01

    We found that the maximum emission of the tryptophyl fluorescence of hen egg-white lysozyme is shifted from 337 to 323 nm and quenched to the extent of 55% with an increase in concentrations of NiCl 2 from 0 to 2 M in 50 mM Na acetate buffer (pH 4.7). In contrast, NaCl does not influence the fluorescence of lysozyme up to 2 M. To elucidate the particular effects of Ni 2+ on the tryptophyl fluorescence of lysozyme, we have measured the assembly behavior and secondary structure of lysozyme in various concentrations of NiCl 2 , and determined the structures of lysozyme crystals grown in 0.3, 0.5, and 1.0 M NiCl 2 , respectively. The results of analytical centrifugation and circular dichroism experiments show that lysozyme keeps a monomer state and has an identical secondary structure, irrespective of NiCl 2 concentrations. The crystal structures show that all crystals grown in different concentrations of NiCl 2 have an identical main chain and side chain conformation. And one Ni 2+ binding with Oδ atom of Asp52 in the active site and coordinating with five water molecules to form hexagonal coordination has been determined for each crystal structure. Based on these results, we have proposed that Ni 2+ quenches the fluorescence of Trp62 and Trp108 due to the binding of Ni 2+ to the active site of lysozyme

  17. Structural model of the open–closed–inactivated cycle of prokaryotic voltage-gated sodium channels

    Science.gov (United States)

    Bagnéris, Claire; Naylor, Claire E.; McCusker, Emily C.

    2015-01-01

    In excitable cells, the initiation of the action potential results from the opening of voltage-gated sodium channels. These channels undergo a series of conformational changes between open, closed, and inactivated states. Many models have been proposed for the structural transitions that result in these different functional states. Here, we compare the crystal structures of prokaryotic sodium channels captured in the different conformational forms and use them as the basis for examining molecular models for the activation, slow inactivation, and recovery processes. We compare structural similarities and differences in the pore domains, specifically in the transmembrane helices, the constrictions within the pore cavity, the activation gate at the cytoplasmic end of the last transmembrane helix, the C-terminal domain, and the selectivity filter. We discuss the observed differences in the context of previous models for opening, closing, and inactivation, and present a new structure-based model for the functional transitions. Our proposed prokaryotic channel activation mechanism is then compared with the activation transition in eukaryotic sodium channels. PMID:25512599

  18. The Challenge of Interpreting Glutamate-Receptor Ion-Channel Structures.

    Science.gov (United States)

    Mayer, Mark L

    2017-11-21

    Ion channels activated by glutamate mediate excitatory synaptic transmission in the central nervous system. Similar to other ligand-gated ion channels, their gating cycle begins with transitions from a ligand-free closed state to glutamate-bound active and desensitized states. In an attempt to reveal the molecular mechanisms underlying gating, numerous structures for glutamate receptors have been solved in complexes with agonists, antagonists, allosteric modulators, and auxiliary proteins. The embarrassingly rich library of structures emerging from this work reveals very dynamic molecules with a more complex conformational spectrum than anticipated from functional studies. Unanticipated conformations solved for complexes with competitive antagonists and a lack of understanding of the structural basis for ion channel subconductance states further highlight challenges that have yet to be addressed. Published by Elsevier Inc.

  19. Numerical simulation of coherent structures in axial flow through a rectangular channel containing a cylindrical rod

    International Nuclear Information System (INIS)

    Tavoularis, S.; Madrane, A.; Vaillancourt, R.

    2002-01-01

    Exploratory RANS and LES computations of turbulent flow in a rectangular channel containing a single cylindrical rod have been performed, with particular interest in the flow structure near the gap between the rod and the channel wall. The Reynolds number for the channel flow was 108,000. The computations document the formation of a sequence of large-scale, quasi-periodic pairs of counter-rotating vortices that dominate the flow in the gap region and whose effects extend far beyond the gap region. The unsteady RANS computation predict a transient state of such structures giving way to steady axial flow, while the LES computations reproduce a continuing sequence of similar structures. The simulations arc compared to recent experimental results in the same configuration. (author)

  20. Optimisation of the antifungal potency of the amidated peptide H-Orn-Orn-Trp-Trp-NH2 against food contaminants.

    Science.gov (United States)

    Thery, Thibaut; O'Callaghan, Yvonne; O'Brien, Nora; Arendt, Elke K

    2018-01-16

    The design of novel efficient antimicrobial peptides (AMPs) faces several issues, such as cost of synthesis, proteolytic stability or cytotoxicity. The identification of key determinants involved in the activity of AMPs, such as cationicity and amphipathicity, allowed the synthesis of short peptides with optimized properties. An ultrashort peptide made of the sequence H-Orn-Orn-Trp-Trp-NH2 (O3TR) showed antifungal activity against several contaminants from food products. This peptide inhibited the growth of the filamentous fungi Fusarium culmorum, Penicillium expansum and Aspergillus niger within a range of concentration of 12.5-50μg/ml. In addition, O3TR inhibited the growth of the yeast Saccharomyces cerevisiae, Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Debaryomyces hansenii and Kluyveromyces lactis within the range 12.5-50μg/ml. A derivative peptide, called C12O3TR, made by the addition of lauric acid at the N-terminus of O3TR was 2- to 8-fold more active than O3TR against every species. In addition to the inhibition of conidial germination, O3TR and C12O3TR killed F. culmorum hyphae at 100 and 50μg/ml respectively. The MIC of the two peptides against F. culmorum and Z. bailii after heat treatment at 100°C for 60 min and within the pH range 3-10, were not changed. However, the activity of O3TR against F.culmorum and Z. bailii was strongly reduced in salt solutions, whereas the lauric acid peptide kept its antifungal activity and resistance to proteolytic digestion. The conjugation with lauric acid reduced the random coiled structure and increased the α-helical content of O3TR. After conjugation with the dye tetramethylrhodamine (TMR), both peptides entered F. culmorum spores. They also both induced permeabilization of F. culmorum hyphae but only C12O3TR permeabilized Z. bailii membrane. In contrast to the lipopeptide, O3TR did not show haemolytic or cytotoxic activity when applied at the concentrations that exhibited antifungal potency. The two

  1. Structural Changes Fundamental to Gating of the Cystic Fibrosis Transmembrane Conductance Regulator Anion Channel Pore.

    Science.gov (United States)

    Linsdell, Paul

    2017-01-01

    Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial cell anion channel. Potentiator drugs used in the treatment of cystic fibrosis act on the channel to increase overall channel function, by increasing the stability of its open state and/or decreasing the stability of its closed state. The structure of the channel in either the open state or the closed state is not currently known. However, changes in the conformation of the protein as it transitions between these two states have been studied using functional investigation and molecular modeling techniques. This review summarizes our current understanding of the architecture of the transmembrane channel pore that controls the movement of chloride and other small anions, both in the open state and in the closed state. Evidence for different kinds of changes in the conformation of the pore as it transitions between open and closed states is described, as well as the mechanisms by which these conformational changes might be controlled to regulate normal channel gating. The ways that key conformational changes might be targeted by small compounds to influence overall CFTR activity are also discussed. Understanding the changes in pore structure that might be manipulated by such small compounds is key to the development of novel therapeutic strategies for the treatment of cystic fibrosis.

  2. A comprehensive structural model for the human KCNQ1/KCNE1 ion channel.

    Science.gov (United States)

    Jalily Hasani, Horia; Ahmed, Marawan; Barakat, Khaled

    2017-11-01

    The voltage-gated KCNQ1/KCNE1 potassium ion channel complex, forms the slow delayed rectifier (I Ks ) current in the heart, which plays an important role in heart signaling. The importance of KCNQ1/KCNE1 channel's function is further implicated by the linkage between loss-of-function and gain-of-function mutations in KCNQ1 or KCNE1, and long QT syndromes, congenital atrial fibrillation, and short QT syndrome. Also, KCNQ1/KCNE1 channels are an off-target for many non-cardiovascular drugs, leading to fatal cardiac irregularities. One solution to address and study the mentioned aspects of KCNQ1/KNCE1 channel would be the structural studies using a validated and accurate model. Along the same line in this study, we have used several top-notch modeling approaches to build a structural model for the open state of KCNQ1 protein, which is both accurate and compatible with available experimental data. Next, we included the KCNE1 protein components using data-driven protein-protein docking simulations, encompassing a 4:2 stoichiometry to complete the picture of the channel complex formed by these two proteins. All the protein systems generated through these processes were refined by long Molecular Dynamics simulations. The refined models were analyzed extensively to infer data about the interaction of KCNQ1 channel with its accessory KCNE1 beta subunits. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Flow structure and channel morphodynamics of meander bend chute cutoffs: A case study of the Wabash River, USA

    Science.gov (United States)

    Zinger, Jessica A.; Rhoads, Bruce L.; Best, James L.; Johnson, Kevin K.

    2013-12-01

    paper documents the three-dimensional structure of flow and bed morphology of two developing chute cutoffs on a single meander bend on the lower Wabash River, USA, and relates the flow structure to patterns of morphologic change in the evolving cutoff channels. The upstream end of the cutoff channels is characterized by: (1) a zone of flow velocity reduction/stagnation and bar development in the main channel across from the cutoff entrance, (2) flow separation and bar development along the inner (left) bank of the cutoff channel immediately downstream from the cutoff entrance, and (3) helical motion and outward advection of flow momentum entering the cutoff channel, leading to erosion of the outer (right) bank of the cutoff channel. At the downstream end of the cutoff channels, the major hydrodynamic and morphologic features are: (1) flow stagnation along the bank of the main channel immediately upstream of the cutoff channel mouth, (2) convergence of flows from the cutoff and main channels, (3) helical motion of flow from the cutoff, (4) a zone of reduced velocity along the bank of the main channel immediately downstream from the cutoff channel mouth, and (5) development of a prominent bar complex that penetrates into the main channel and extends from the stagnation zone upstream to downstream of the cutoff mouth. These results provide the basis for a conceptual model of chute-cutoff dynamics in which the upstream and downstream ends of a cutoff channel are treated as a bifurcation and confluence, respectively.

  4. Quaternary ammonium compounds as structural probes of single batrachotoxin-activated Na+ channels

    Science.gov (United States)

    1991-01-01

    Quaternary ammonium (QA) blockers are well-known structural probes for studying the permeation pathway of voltage-gated K+ channels. In this study we have examined the effects of a series of n-alkyl- trimethylammonium compounds (Cn-QA) on batrachotoxin (BTX)-activated Na+ channels from skeletal muscle incorporated into planar lipid bilayers. We found that these amphipathic QA compounds (Cn-QA where n = 10-18) block single Na+ channels preferentially from the internal side with equilibrium dissociation constants (KD) in the submicromolar to micromolar range. External application of amphipathic QA compounds is far less effective, by a factor of greater than 200. The block can be described by a QA molecule binding to a single site in the Na+ channel permeation pathway. QA binding affinity is dependent on transmembrane voltage with an effective valence (delta) of approximately 0.5. QA dwell times (given as mean closed times, tau c) increase as a function of n-alkyl chain length, ranging from approximately 13 ms for C10-QA to 500 ms for C18-QA at +50 mV. The results imply that there is a large hydrophobic region within the Na+ channel pore which accepts up to 18 methylene groups of the Cn-QA cation. This hydrophobic domain may be of clinical significance since it also interacts with local anesthetics such as cocaine and mepivacaine. Finally, like BTX-activated Na+ channels in bilayers, unmodified Na+ channels in GH3 cells are also susceptible to QA block. Amphipathic QA cations elicit both tonic and use-dependent inhibitions of normal Na+ currents in a manner similar to that of local anesthetic cocaine. We conclude that amphipathic QA compounds are valuable structural probes to study the permeation pathway of both normal and BTX-activated Na+ channels. PMID:1662681

  5. Development of Chemically Defined Media to Express Trp-Analog-Labeled Proteins in a Lactococcus lactis Trp Auxotroph.

    Science.gov (United States)

    Shao, Jinfeng; Marcondes, Marcelo F M; Oliveira, Vitor; Broos, Jaap

    2016-01-01

    Chemically defined media for growth of Lactococcus lactis strains contain about 50 components, making them laborious and expensive growth media. However, they are crucial for metabolism studies as well as for expression of heterologous proteins labeled with unnatural amino acids. In particular, the L. lactis Trp auxotroph PA1002, overexpressing the tryptophanyl tRNA synthetase enzyme of L. lactis, is very suitable for the biosynthetic incorporation of Trp analogs in proteins because of its most relaxed substrate specificity reported towards Trp analogs. Here we present two much simpler defined media for L. lactis, which consist of only 24 or 31 components, respectively, and with which the L. lactis Trp auxotroph shows similar growth characteristics as with a 50-component chemically defined medium. Importantly, the expression levels of two recombinant proteins used for evaluation were up to 2-3 times higher in these new media than in the 50-component medium, without affecting the Trp analog incorporation efficiency. Taken together, the simplest chemically defined media reported so far for L. lactis are presented. Since L. lactis also shows auxotrophy for Arg, His, Ile, Leu Val, and Met, our simplified media may also be useful for the biosynthetic incorporation of analogs of these five amino acids. © 2016 The Author(s) Published by S. Karger AG, Basel.

  6. Evolutionary and structural perspectives of plant cyclic nucleotide-gated cation channels

    KAUST Repository

    Zelman, Alice K.

    2012-05-29

    Ligand-gated cation channels are a frequent component of signaling cascades in eukaryotes. Eukaryotes contain numerous diverse gene families encoding ion channels, some of which are shared and some of which are unique to particular kingdoms. Among the many different types are cyclic nucleotide-gated channels (CNGCs). CNGCs are cation channels with varying degrees of ion conduction selectivity. They are implicated in numerous signaling pathways and permit diffusion of divalent and monovalent cations, including Ca2+ and K+. CNGCs are present in both plant and animal cells, typically in the plasma membrane; recent studies have also documented their presence in prokaryotes. All eukaryote CNGC polypeptides have a cyclic nucleotide-binding domain and a calmodulin binding domain as well as a six transmembrane/one pore tertiary structure. This review summarizes existing knowledge about the functional domains present in these cation-conducting channels, and considers the evidence indicating that plant and animal CNGCs evolved separately. Additionally, an amino acid motif that is only found in the phosphate binding cassette and hinge regions of plant CNGCs, and is present in all experimentally confirmed CNGCs but no other channels was identified. This CNGC-specific amino acid motif provides an additional diagnostic tool to identify plant CNGCs, and can increase confidence in the annotation of open reading frames in newly sequenced genomes as putative CNGCs. Conversely, the absence of the motif in some plant sequences currently identified as probable CNGCs may suggest that they are misannotated or protein fragments. 2012 Zelman, Dawe, Gehring and Berkowitz.

  7. Microfluidic channel structures speed up mixing of multiple emulsions by a factor of ten

    CSIR Research Space (South Africa)

    Land, KJ

    2014-09-01

    Full Text Available We present a novel use for channel structures in microfluidic devices, whereby two two-phase emulsions, one created on-chip, the other off-chip, are rapidly mixed with each other in order to allow for the coalescence of one emulsion with the other...

  8. Threadfin shad impacts phytoplankton and zooplankton community structures in channel catfish ponds

    Science.gov (United States)

    Plankton community structure and chlorophyll a concentration were compared in 12 0.1-ha earthen ponds co-stocked with channel catfish (Ictalurus punctatus Rafinesque, 1818) in multiple-batch culture (initial biomass = 5,458 kg ha-1) and a planktivore, threadfin shad (Dorosoma petenense Güther, 1867;...

  9. Wetting properties of hybrid structure with hydrophilic ridges and hydrophobic channels

    Science.gov (United States)

    Lee, Dong-Ki; Choi, Su Young; Park, Min Soo; Cho, Young Hak

    2018-02-01

    In the present study, we fabricated a hybrid structure where the upper surface of the ridge is hydrophilic and the inner surface of the channel is hydrophobic. Laser-induced backside wet etching (LIBWE) process was performed to machine the hybrid structure on a Pyrex glass substrate. Wetting properties were evaluated from static contact angles (CAs) measurement in parallel and orthogonal directions. The water droplet on the hybrid structure was in the Cassie-Baxter state and showed anisotropic wetting property along groove lines. Moisture condensation studies under humid condition indicated that water droplets grew and coalesced on the ridge with hydrophilicity. Furthermore, water-oil separation was tested using a microfluidic chip with the developed hybrid structure. In case of hybrid microfluidic chip, the water could not flow into channel but the hexadecane could flow due to the capillary pressure difference.

  10. Spectrins: a structural platform for stabilization and activation of membrane channels, receptors and transporters.

    Science.gov (United States)

    Machnicka, Beata; Czogalla, Aleksander; Hryniewicz-Jankowska, Anita; Bogusławska, Dżamila M; Grochowalska, Renata; Heger, Elżbieta; Sikorski, Aleksander F

    2014-02-01

    This review focuses on structure and functions of spectrin as a major component of the membrane skeleton. Recent advances on spectrin function as an interface for signal transduction mediation and a number of data concerning interaction of spectrin with membrane channels, adhesion molecules, receptors and transporters draw a picture of multifaceted protein. Here, we attempted to show the current depiction of multitask role of spectrin in cell physiology. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Burst pressure of phaseguide structures of different heights in all-polymer microfluidic channels

    Science.gov (United States)

    Garbarino, Francesca; Kistrup, Kasper; Rizzi, Giovanni; Fougt Hansen, Mikkel

    2017-12-01

    We present an experimental investigation of the burst/overflow pressure of water and a representative surfactant-containing buffer in microfluidic channels with phaseguide structures oriented at an angle of 90° to the channel length as a function of their height, h . The all-polymer chips were fabricated by injection moulding and sealed by ultrasonic welding. Channels with a height of 200 μ m and widths of 1 mm or 3 mm were investigated for five values of h between 8 μ m and 82 μ m. Phaseguide structures without branches and with branches at angles α   =  45°, 60° and 75° were studied. All phaseguide structures were found able to pin both liquids and the burst pressure was found to increase approximately linearly with the height of the phaseguide from about 100-350 Pa for water and from about 25-200 Pa for the buffer. The burst pressure was found not to depend on the channel width and it was only weakly influenced by the presence of a branch on the phaseguide. For phaseguides with a branch, the liquid was always found to burst at the branch location. The measured burst pressures were compared to those estimated using a simple theory. The knowledge obtained in this study enables simple tuning of liquid spreading and overflow in microfluidic channels by use of phaseguide structures with different heights and it also provides a set of systematic experimental data to be compared with simulations/theory.

  12. Structure and inhibition of the SARS coronavirus envelope protein ion channel.

    Directory of Open Access Journals (Sweden)

    Konstantin Pervushin

    2009-07-01

    Full Text Available The envelope (E protein from coronaviruses is a small polypeptide that contains at least one alpha-helical transmembrane domain. Absence, or inactivation, of E protein results in attenuated viruses, due to alterations in either virion morphology or tropism. Apart from its morphogenetic properties, protein E has been reported to have membrane permeabilizing activity. Further, the drug hexamethylene amiloride (HMA, but not amiloride, inhibited in vitro ion channel activity of some synthetic coronavirus E proteins, and also viral replication. We have previously shown for the coronavirus species responsible for severe acute respiratory syndrome (SARS-CoV that the transmembrane domain of E protein (ETM forms pentameric alpha-helical bundles that are likely responsible for the observed channel activity. Herein, using solution NMR in dodecylphosphatidylcholine micelles and energy minimization, we have obtained a model of this channel which features regular alpha-helices that form a pentameric left-handed parallel bundle. The drug HMA was found to bind inside the lumen of the channel, at both the C-terminal and the N-terminal openings, and, in contrast to amiloride, induced additional chemical shifts in ETM. Full length SARS-CoV E displayed channel activity when transiently expressed in human embryonic kidney 293 (HEK-293 cells in a whole-cell patch clamp set-up. This activity was significantly reduced by hexamethylene amiloride (HMA, but not by amiloride. The channel structure presented herein provides a possible rationale for inhibition, and a platform for future structure-based drug design of this potential pharmacological target.

  13. A conceptual design of the ITER upper port plug structure and its cooling channels

    International Nuclear Information System (INIS)

    Pak, S.I.; Lee, H.G.; Jung, K.J.; Walker, C.I.; Kim, D.G.; Choi, K.S.

    2008-01-01

    A study is conducted on the conceptual design of the structure and cooling channels of the upper port plug of International Thermonuclear Experimental Reactor (ITER). Modification of the earlier port plug design is made and a simple fabrication method is proposed. It is shown that the newly designed port plug can accommodate the installation of both diagnostic and electron cyclotron heating (ECH) devices. Design assessment is carried out through structural and thermo-hydraulic analyses. Results of the analyses show that the port plug structure is stable against one of the most severe plasma events and the total pressure drop of the coolant is within the allowable level

  14. Phosphorylation of the Drosophila transient receptor potential ion channel is regulated by the phototransduction cascade and involves several protein kinases and phosphatases.

    Directory of Open Access Journals (Sweden)

    Olaf Voolstra

    Full Text Available Protein phosphorylation plays a cardinal role in regulating cellular processes in eukaryotes. Phosphorylation of proteins is controlled by protein kinases and phosphatases. We previously reported the light-dependent phosphorylation of the Drosophila transient receptor potential (TRP ion channel at multiple sites. TRP generates the receptor potential upon stimulation of the photoreceptor cell by light. An eye-enriched protein kinase C (eye-PKC has been implicated in the phosphorylation of TRP by in vitro studies. Other kinases and phosphatases of TRP are elusive. Using phosphospecific antibodies and mass spectrometry, we here show that phosphorylation of most TRP sites depends on the phototransduction cascade and the activity of the TRP ion channel. A candidate screen to identify kinases and phosphatases provided in vivo evidence for an involvement of eye-PKC as well as other kinases and phosphatases in TRP phosphorylation.

  15. The Structure and Transport of Water and Hydrated Ions Within Hydrophobic, Nanoscale Channels

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Herberg, J L; Wu, Y; Schwegler, E; Mehta, A

    2009-06-15

    The purpose of this project includes an experimental and modeling investigation into water and hydrated ion structure and transport at nanomaterials interfaces. This is a topic relevant to understanding the function of many biological systems such as aquaporins that efficiently shuttle water and ion channels that permit selective transport of specific ions across cell membranes. Carbon nanotubes (CNT) are model nanoscale, hydrophobic channels that can be functionalized, making them artificial analogs for these biological channels. This project investigates the microscopic properties of water such as water density distributions and dynamics within CNTs using Nuclear Magnetic Resonance (NMR) and the structure of hydrated ions at CNT interfaces via X-ray Absorption Spectroscopy (XAS). Another component of this work is molecular simulation, which can predict experimental measurables such as the proton relaxation times, chemical shifts, and can compute the electronic structure of CNTs. Some of the fundamental questions this work is addressing are: (1) what is the length scale below which nanoscale effects such as molecular ordering become important, (2) is there a relationship between molecular ordering and transport?, and (3) how do ions interact with CNT interfaces? These are questions of interest to the scientific community, but they also impact the future generation of sensors, filters, and other devices that operate on the nanometer length scale. To enable some of the proposed applications of CNTs as ion filtration media and electrolytic supercapacitors, a detailed knowledge of water and ion structure at CNT interfaces is critical.

  16. Structural basis of dual Ca2+/pH regulation of the endolysosomal TRPML1 channel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Minghui; Zhang, Wei K.; Benvin, Nicole M.; Zhou, Xiaoyuan; Su, Deyuan; Li, Huan; Wang, Shu; Michailidis, Ioannis E.; Tong, Liang; Li, Xueming; Yang, Jian

    2017-01-23

    The activities of organellar ion channels are often regulated by Ca2+ and H+, which are present in high concentrations in many organelles. Here we report a structural element critical for dual Ca2+/pH regulation of TRPML1, a Ca2+-release channel crucial for endolysosomal function. TRPML1 mutations cause mucolipidosis type IV (MLIV), a severe lysosomal storage disorder characterized by neurodegeneration, mental retardation and blindness. We obtained crystal structures of the 213-residue luminal domain of human TRPML1 containing three missense MLIV-causing mutations. This domain forms a tetramer with a highly electronegative central pore formed by a novel luminal pore loop. Cysteine cross-linking and cryo-EM analyses confirmed that this architecture occurs in the full-length channel. Structure–function studies demonstrated that Ca2+ and H+ interact with the luminal pore and exert physiologically important regulation. The MLIV-causing mutations disrupt the luminal-domain structure and cause TRPML1 mislocalization. Our study reveals the structural underpinnings of TRPML1's regulation, assembly and pathogenesis.

  17. Interaction of a peptide derived from C-terminus of human TRPA1 channel with model membranes mimicking the inner leaflet of the plasma membrane.

    Science.gov (United States)

    Witschas, Katja; Jobin, Marie-Lise; Korkut, Dursun Nizam; Vladan, Maria Magdalena; Salgado, Gilmar; Lecomte, Sophie; Vlachova, Viktorie; Alves, Isabel D

    2015-05-01

    The transient receptor potential ankyrin 1 channel (TRPA1) belongs to the TRP cation channel superfamily that responds to a panoply of stimuli such as changes in temperature, calcium levels, reactive oxygen and nitrogen species and lipid mediators among others. The TRP superfamily has been implicated in diverse pathological states including neurodegenerative disorders, kidney diseases, inflammation, pain and cancer. The intracellular C-terminus is an important regulator of TRP channel activity. Studies with this and other TRP superfamily members have shown that the C-terminus association with lipid bilayer alters channel sensitivity and activation, especially interactions occurring through basic residues. Nevertheless, it is not yet clear how this process takes place and which regions in the C-terminus would be responsible for such membrane recognition. With that in mind, herein the first putative membrane interacting region of the C-terminus of human TRPA1, (corresponding to a 29 residue peptide, IAEVQKHASLKRIAMQVELHTSLEKKLPL) named H1 due to its potential helical character was chosen for studies of membrane interaction. The affinity of H1 to lipid membranes, H1 structural changes occurring upon this interaction as well as effects of this interaction in lipid organization and integrity were investigated using a biophysical approach. Lipid models systems composed of zwitterionic and anionic lipids, namely those present in the lipid membrane inner leaflet, where H1 is prone to interact, where used. The study reveals a strong interaction and affinity of H1 as well as peptide structuration especially with membranes containing anionic lipids. Moreover, the interactions and peptide structure adoption are headgroup specific. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Homologue Structure of the SLAC1 Anion Channel for Closing Stomata in Leaves

    Energy Technology Data Exchange (ETDEWEB)

    Y Chen; L Hu; M Punta; R Bruni; B Hillerich; B Kloss; B Rost; J Love; S Siegelbaum; W Hendrickson

    2011-12-31

    The plant SLAC1 anion channel controls turgor pressure in the aperture-defining guard cells of plant stomata, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought or high levels of carbon dioxide. Here we determine the crystal structure of a bacterial homologue (Haemophilus influenzae) of SLAC1 at 1.20 {angstrom} resolution, and use structure-inspired mutagenesis to analyse the conductance properties of SLAC1 channels. SLAC1 is a symmetrical trimer composed from quasi-symmetrical subunits, each having ten transmembrane helices arranged from helical hairpin pairs to form a central five-helix transmembrane pore that is gated by an extremely conserved phenylalanine residue. Conformational features indicate a mechanism for control of gating by kinase activation, and electrostatic features of the pore coupled with electrophysiological characteristics indicate that selectivity among different anions is largely a function of the energetic cost of ion dehydration.

  19. Investigation of Short Channel Effect on Vertical Structures in Nanoscale MOSFET

    Directory of Open Access Journals (Sweden)

    Munawar A. Riyadi

    2009-12-01

    Full Text Available The recent development of MOSFET demands innovative approach to maintain the scaling into nanoscale dimension. This paper focuses on the physical nature of vertical MOSFET in nanoscale regime. Vertical structure is one of the promising devices in further scaling, with relaxed-lithography feature in the manufacture. The comparison of vertical and lateral MOSFET performance for nanoscale channel length (Lch is demonstrated with the help of numerical tools. The evaluation of short channel effect (SCE parameters, i.e. threshold voltage roll-off, subthreshold swing (SS, drain induced barrier lowering (DIBL and leakage current shows the considerable advantages as well as its thread-off in implementing the structure, in particular for nanoscale regime.

  20. Structural analysis of the S4-S5 linker of the human KCNQ1 potassium channel.

    Science.gov (United States)

    Gayen, Shovanlal; Li, Qingxin; Kang, CongBao

    2015-01-02

    KCNQ1 plays important roles in the cardiac action potential and consists of an N-terminal domain, a voltage-sensor domain, a pore domain and a C-terminal domain. KCNQ1 is a voltage-gated potassium channel and its channel activity is regulated by membrane potentials. The linker between transmembrane helices 4 and 5 (S4-S5 linker) is important for transferring the conformational changes from the voltage-sensor domain to the pore domain. In this study, the structure of the S4-S5 linker of KCNQ1 was investigated by solution NMR, circular dichroism and fluorescence spectroscopic studies. The S4-S5 linker adopted a helical structure in detergent micelles. The W248 may interact with the cell membrane. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Turbulent flow in a ribbed channel: Flow structures in the vicinity of a rib

    DEFF Research Database (Denmark)

    Wang, Lei; Salewski, Mirko; Sundén, Bengt

    2010-01-01

    PIV measurements are performed in a channel with periodic ribs on one wall. The emphasis of this study is to investigate the flow structures in the vicinity of a rib in terms of mean velocities, Reynolds stresses, probability density functions (PDF), and two-point correlations. The PDF distributi......-based visualization is applied to the separation bubble upstream of the rib. Salient critical points and limit cycles are extracted, which gives clues to the physical processes occurring in the flow....

  2. Structure of the channeling electrons wave functions under dynamical chaos conditions

    International Nuclear Information System (INIS)

    Shul’ga, N.F.; Syshchenko, V.V.; Tarnovsky, A.I.; Isupov, A.Yu.

    2016-01-01

    The stationary wave functions of fast electrons axially channeling in the silicon crystal near [1 1 0] direction have been found numerically for integrable and non-integrable cases, for which the classical motion is regular and chaotic, respectively. The nodal structure of the wave functions in the quasi-classical region, where the energy levels density is high, is agreed with quantum chaos theory predictions.

  3. Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel

    Energy Technology Data Exchange (ETDEWEB)

    Bera, Asim K; Aukema, Kelly G.; Elias, Mikael; Wackett, Lawrence P. (UMM)

    2017-03-27

    Cyanuric acid hydrolases are of industrial importance because of their use in aquatic recreational facilities to remove cyanuric acid, a stabilizer for the chlorine. Degradation of excess cyanuric acid is necessary to maintain chlorine disinfection in the waters. Cyanuric acid hydrolase opens the cyanuric acid ring hydrolytically and subsequent decarboxylation produces carbon dioxide and biuret. In the present study, we report the X-ray structure of TrzD, a cyanuric acid hydrolase from Acidovorax citrulli. The crystal structure at 2.19 Å resolution shows a large displacement of the catalytic lysine (Lys163) in domain 2 away from the active site core, whereas the two other active site lysines from the two other domains are not able to move. The lysine displacement is proposed here to open up a channel for product release. Consistent with that, the structure also showed two molecules of the co-product, carbon dioxide, one in the active site and another trapped in the proposed exit channel. Previous data indicated that the domain 2 lysine residue plays a role in activating an adjacent serine residue carrying out nucleophilic attack, opening the cyanuric acid ring, and the mobile lysine guides products through the exit channel.

  4. Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel.

    Science.gov (United States)

    Bera, Asim K; Aukema, Kelly G; Elias, Mikael; Wackett, Lawrence P

    2017-03-27

    Cyanuric acid hydrolases are of industrial importance because of their use in aquatic recreational facilities to remove cyanuric acid, a stabilizer for the chlorine. Degradation of excess cyanuric acid is necessary to maintain chlorine disinfection in the waters. Cyanuric acid hydrolase opens the cyanuric acid ring hydrolytically and subsequent decarboxylation produces carbon dioxide and biuret. In the present study, we report the X-ray structure of TrzD, a cyanuric acid hydrolase from Acidovorax citrulli. The crystal structure at 2.19 Å resolution shows a large displacement of the catalytic lysine (Lys163) in domain 2 away from the active site core, whereas the two other active site lysines from the two other domains are not able to move. The lysine displacement is proposed here to open up a channel for product release. Consistent with that, the structure also showed two molecules of the co-product, carbon dioxide, one in the active site and another trapped in the proposed exit channel. Previous data indicated that the domain 2 lysine residue plays a role in activating an adjacent serine residue carrying out nucleophilic attack, opening the cyanuric acid ring, and the mobile lysine guides products through the exit channel.

  5. High Resolution Inkjet Printed Oxide Thin Film Transistors with Self-Aligned Fine Channel Bank Structure.

    Science.gov (United States)

    Zhang, Qing; Shao, Shuangshuang; Chen, Zheng; Pecunia, Vincenzo; Xia, Kai; Zhao, Jianwen; Cui, Zheng

    2018-04-12

    A self-aligned inkjet printing process has been developed to construct small channel metal oxide (a-IGZO) thin-film transistors (TFTs) with independent bottom gates on transparent glass substrates. Poly(methylsilsesquioxane) (PMSQ) was used to pattern hydrophobic banks on the transparent substrate instead of commonly used self-assembled octadecyltrichlorosilane (OTS). Photolithographic exposure from backside using bottom gate electrodes as mask formed hydrophilic channel areas for the TFTs. IGZO ink was selectively deposited by an inkjet printer in the hydrophilic channel region and confined by the hydrophobic bank structure, resulting in the precise deposition of semiconductor layers just above the gate electrodes. Inkjet-printed IGZO TFTs with independent gate electrodes of 10 μm width have been demonstrated, avoiding completely printed channel beyond the broad of the gate electrodes. The TFTs showed on/off ratios of 10 8 , maximum mobility of 3.3 cm 2 V -1 s -1 , negligible hysteresis and good uniformity. This method is conductive to minimizing the area of printed TFTs so as to the development of high resolution printing displays.

  6. Functional Role of Transient Receptor Potential Channels in Immune Cells and Epithelia

    Directory of Open Access Journals (Sweden)

    Mohammad Khalil

    2018-02-01

    Full Text Available Transient receptor potential (TRP ion channels are widely expressed in several tissues throughout the mammalian organism. Originally, TRP channel physiology was focusing on its fundamental meaning in sensory neuronal function. Today, it is known that activation of several TRP ion channels in peptidergic neurons does not only result in neuropeptide release and consecutive neurogenic inflammation. Growing evidence demonstrates functional extra-neuronal TRP channel expression in immune and epithelial cells with important implications for mucosal immunology. TRP channels maintain intracellular calcium homeostasis to regulate various functions in the respective cells such as nociception, production and release of inflammatory mediators, phagocytosis, and cell migration. In this review, we provide an overview about TRP-mediated effects in immune and epithelial cells with an emphasis on mucosal immunology of the gut. Crosstalk between neurons, epithelial cells, and immune cells induced by activation of TRP channels orchestrates the immunologic response. Understanding of its molecular mechanisms paves the way to novel clinical approaches for the treatment of various inflammatory disorders including IBD.

  7. Fish assemblages at engineered and natural channel structures in the lower Missouri river: implications for modified dike structures

    Science.gov (United States)

    Schloesser, J.T.; Paukert, Craig P.; Doyle, W.J.; Hill, T.; Steffensen, K.D.; Travnichek, Vincent H.

    2012-01-01

    Large rivers throughout the world have been modified by using dike structures to divert water flows to deepwater habitats to maintain navigation channels. These modifications have been implicated in the decline in habitat diversity and native fishes. However, dike structures have been modified in the Missouri River USA to increase habitat diversity to aid in the recovery of native fishes. We compared species occupancy and fish community composition at natural sandbars and at notched and un-notched rock dikes along the lower Missouri River to determine if notching dikes increases species diversity or occupancy of native fishes. Fish were collected using gill nets, trammel nets, otter trawls, and mini fyke nets throughout the lower 1212 river km of the Missouri River USA from 2003 to 2006. Few differences in species richness and diversity were evident among engineered dike structures and natural sandbars. Notching a dike structure had no effect on proportional abundance of fluvial dependents, fluvial specialists, and macrohabitat generalists. Occupancy at notched dikes increased for two species but did not differ for 17 other species (81%). Our results suggest that dike structures may provide suitable habitats for fluvial species compared with channel sand bars, but dike notching did not increase abundance or occupancy of most Missouri River fishes. Published in 2011 by John Wiley & Sons, Ltd.

  8. Structural characteristics of the redox-sensing coiled coil in the voltage-gated H+ channel.

    Science.gov (United States)

    Fujiwara, Yuichiro; Takeshita, Kohei; Nakagawa, Atsushi; Okamura, Yasushi

    2013-06-21

    Oxidation is an important biochemical defense mechanism, but it also elicits toxicity; therefore, oxidation must be under strict control. In phagocytotic events in neutrophils, the voltage-gated H(+) (Hv) channel is a key regulator of the production of reactive oxygen species against invading bacteria. The cytoplasmic domain of the Hv channel forms a dimeric coiled coil underpinning a dimerized functional unit. Importantly, in the alignment of the coiled-coil core, a conserved cysteine residue forms a potential intersubunit disulfide bond. In this study, we solved the crystal structures of the coiled-coil domain in reduced, oxidized, and mutated (Cys → Ser) states. The crystal structures indicate that a pair of Cys residues forms an intersubunit disulfide bond dependent on the redox conditions. CD spectroscopy revealed that the disulfide bond increases the thermal stability of the coiled-coil protein. We also reveal that two thiol modifier molecules are able to bind to Cys in a redox-dependent manner without disruption of the dimeric coiled-coil assembly. Thus, the biochemical properties of the cytoplasmic coiled-coil domain in the Hv channel depend on the redox condition, which may play a role in redox sensing in the phagosome.

  9. Statistical Investigation on Coherent Vortex Structure in Turbulent Drag Reducing Channel Flow with Blown Polymer Solution

    International Nuclear Information System (INIS)

    Ishitsuka, Shota; Motozawa, Masaaki; Kawaguchi, Yasuo; Iwamoto, Kaoru; Ando, Hirotomo; Senda, Tetsuya

    2011-01-01

    Coherent vortex structure in turbulent drag-reducing channel flow with blown polymer solution from the wall was investigated. As a statistical analysis, we carried out Galilean decomposition, swirling strength and linear stochastic estimation of the PIV data obtained by the PIV measurement in x – y plane. Reynolds number based on bulk velocity and channel height was set to 40000. As a result, the angle of shear layer that cleared up by using Galilean decomposition becomes small in the drag-reducing flow. Q3 events were observed near the shear layer. In addition, as a result of linear stochastic estimation (LSE) based on swirling strength, we confirmed that the velocity under the vortex core is strong in the water flow. This result shows Q2 (ejection) are dominant in the water flow. However, in the drag-reducing flow with blown polymer solution, the velocity above the vortex core become strong, that is, Q4 (sweep) events are relatively strong around the vortex core. This is the result of Q4 events to come from the channel center region because the polymer solution does not exist in this region. The typical structure like this was observed in the drag -reducing flow with blown polymer solution from the wall.

  10. Calcium channel activity of purified human synexin and structure of the human synexin gene

    International Nuclear Information System (INIS)

    Burns, A.L.; Magendzo, K.; Shirvan, A.; Srivastava, M.; Rojas, E.; Alijani, M.R.; Pollard, H.B.

    1989-01-01

    Synexin is a calcium-dependent membrane binding protein that not only fuses membranes but also acts as a voltage-dependent calcium channel. The authors have isolated and sequenced a set of overlapping cDNA clones for human synexin. The derived amino acid sequence of synexin reveals strong homology in the C-terminal domain with a previously identified class of calcium-dependent membrane binding proteins. These include endonexin II, lipocortin I, calpactin I heavy chain (p36), protein II, and calelectrin 67K. The M r 51,000 synexin molecule can be divided into a unique, highly hydrophobic N-terminal domain of 167 amino acids and a conserved C-terminal region of 299 amino acids. The latter domain is composed of alternating hydrophobic and hydrophilic segments. Analysis of the entire structure reveals possible insights into such diverse properties as voltage-sensitive calcium channel activity, ion selectivity, affinity for phospholipids, and membrane fusion

  11. Probing the outer mouth structure of the HERG channel with peptide toxin footprinting and molecular modeling.

    Science.gov (United States)

    Tseng, Gea-Ny; Sonawane, Kailas D; Korolkova, Yuliya V; Zhang, Mei; Liu, Jie; Grishin, Eugene V; Guy, H Robert

    2007-05-15

    Previous studies have shown that the unusually long S5-P linker lining human ether a-go-go related gene's (hERG's) outer vestibule is critical for its channel function: point mutations at high-impact positions here can interfere with the inactivation process and, in many cases, also reduce the pore's K+ selectivity. Because no data are available on the equivalent region in the available K channel crystal structures to allow for homology modeling, we used alternative approaches to model its three-dimensional structure. The first part of this article describes mutant cycle analysis used to identify residues on hERG's outer vestibule that interact with specific residues on the interaction surface of BeKm-1, a peptide toxin with known NMR structure and a high binding affinity to hERG. The second part describes molecular modeling of hERG's pore domain. The transmembrane region was modeled after the crystal structure of KvAP pore domain. The S5-P linker was docked to the transmembrane region based on data from previous NMR and mutagenesis experiments, as well as a set of modeling criteria. The models were further restrained by contact points between hERG's outer vestibule and the bound BeKm-1 toxin molecule deduced from the mutant cycle analysis. Based on these analyses, we propose a working model for the open conformation of the outer vestibule of the hERG channel, in which the S5-P linkers interact with the pore loops to influence ion flux through the pore.

  12. Acid-base titration of melanocortin peptides: evidence of Trp rotational conformers interconversion.

    Science.gov (United States)

    Fernandez, Roberto M; Vieira, Renata F F; Nakaie, Clóvis R; Lamy, M Teresa; Ito, Amando S

    2005-01-01

    Tryptophantime-resolved fluorescence was used to monitor acid-base titration properties of alpha-melanocyte stimulating hormone (alpha-MSH) and the biologically more potent analog [Nle4, D-Phe7]alpha -MSH (NDP-MSH), labeled or not with the paramagnetic amino acid probe 2,2,6,6-tetramthylpiperidine-N-oxyl-4-amino-4-carboxylic acid (Toac). Global analysis of fluorescence decay profiles measured in the pH range between 2.0 and 11.0 showed that, for each peptide, the data could be well fitted to three lifetimes whose values remained constant. The less populated short lifetime component changed little with pH and was ascribed to Trp g+ chi1 rotamer, in which electron transfer deactivation predominates over fluorescence. The long and intermediate lifetime preexponential factors interconverted along that pH interval and the result was interpreted as due to interconversion between Trp g- and trans chi1 rotamers, driven by conformational changes promoted by modifications in the ionization state of side-chain residues. The differences in the extent of interconversion in alpha-MSH and NDP-MSH are indicative of structural differences between the peptides, while titration curves suggest structural similarities between each peptide and its Toac-labeled species, in aqueous solution. Though less sensitive than fluorescence, the Toac electron spin resonance (ESR) isotropic hyperfine splitting parameter can also monitor the titration of side-chain residues located relatively far from the probe. Copyright (c) 2005 Wiley Periodicals, Inc.

  13. Expression of the benign HEXA mutations, Arg247Trp and Arg249Trp, associated with beta-hexosaminidase A pseudodeficiency

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Z.; Petroulakis, E.; Salo, T. [Univ. of Manitoba (Canada)] [and others

    1994-09-01

    {beta}-Hexosaminidase (Hex A) is a heterodimer of {alpha} and {beta} subunits encoded by the HEXA and HEXB genes, respectively. Mutations in the HEXA gene typically cause Tay-Sachs disease or less severe forms of G{sub M2} gangliosidosis. However, two benign mutations (Arg247Trp and Arg249Trp) in the {alpha}-subunit of Hex A account for Hex A deficiency in {approximately}36% of non-Jewish enzyme-defined Tay-Sachs disease carriers. These mutations do not result in any apparent clinical phenotype in individuals who are genetic compounds with a second disease-causing mutation. We expressed the {alpha}-subunit harboring each of the benign mutations separately to study activity toward the synthetic substrate, 4-MUGS, for comparison to activity from enzymes containing mutations associated with other forms of G{sub M2} gangliosidosis. The C739T (Arg247Trp;benign), C745T (Arg 249Trp; benign), G805A (Gly269Ser; adult-onset), G749A (Gly250Asp; juvenile), and C508T (Arg170Trp; infantile) mutations were introduced into the {alpha}-subunit cDNA. These were transfected alone, or with the {beta}-subunit cDNA, to generate Hex S ({alpha}{alpha}) or Hex A ({alpha}{beta}), respectively. The activities were monitored using 4-MUGS, and the levels of {alpha}-subunit protein were assessed by Western blotting. Repeated experiments show that the benign mutations produce approximately 35% of normal Hex S and 40% of normal Hex A activity. This level is much higher than that of Hex A harbouring the Gly169Ser adult-onset mutation (12%). A sequential decrease in expressed Hex A activity is observed as mutations associated with more severe phenotypes are expressed. The benign mutations also result in lower levels of mature {alpha}-subunit protein compared to normal, and slightly reduced levels of {alpha}-subunit precursor protein. The Hex A deficiency resulting from benign mutations is not as great as that associated with disease-causing mutations.

  14. Osteoinduction of porous Ti implants with a channel structure fabricated by selective laser melting.

    Science.gov (United States)

    Fukuda, A; Takemoto, M; Saito, T; Fujibayashi, S; Neo, M; Pattanayak, Deepak K; Matsushita, T; Sasaki, K; Nishida, N; Kokubo, T; Nakamura, T

    2011-05-01

    Many studies have shown that certain biomaterials with specific porous structures can induce bone formation in non-osseous sites without the need for osteoinductive biomolecules, however, the mechanisms responsible for this phenomenon (intrinsic osteoinduction of biomaterials) remain unclear. In particular, to our knowledge the type of pore structure suitable for osteoinduction has not been reported in detail. In the present study we investigated the effects of interconnective pore size on osteoinductivity and the bone formation processes during osteoinduction. Selective laser melting was employed to fabricate porous Ti implants (diameter 3.3mm, length 15 mm) with a channel structure comprising four longitudinal square channels, representing pores, of different diagonal widths, 500, 600, 900, and 1200 μm (termed p500, p600, p900, and p1200, respectively). These were then subjected to chemical and heat treatments to induce bioactivity. Significant osteoinduction was observed in p500 and p600, with the highest observed osteoinduction occurring at 5mm from the end of the implants. A distance of 5mm probably provides a favorable balance between blood circulation and fluid movement. Thus, the simple architecture of the implants allowed effective investigation of the influence of the interconnective pore size on osteoinduction, as well as the relationship between bone quantity and its location for different pore sizes. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Structural basis for ion selectivity revealed by high-resolution crystal structure of Mg2+ channel MgtE.

    Science.gov (United States)

    Takeda, Hironori; Hattori, Motoyuki; Nishizawa, Tomohiro; Yamashita, Keitaro; Shah, Syed T A; Caffrey, Martin; Maturana, Andrés D; Ishitani, Ryuichiro; Nureki, Osamu

    2014-11-04

    Magnesium is the most abundant divalent cation in living cells and is crucial to several biological processes. MgtE is a Mg(2+) channel distributed in all domains of life that contributes to the maintenance of cellular Mg(2+) homeostasis. Here we report the high-resolution crystal structures of the transmembrane domain of MgtE, bound to Mg(2+), Mn(2+) and Ca(2+). The high-resolution Mg(2+)-bound crystal structure clearly visualized the hydrated Mg(2+) ion within its selectivity filter. Based on those structures and biochemical analyses, we propose a cation selectivity mechanism for MgtE in which the geometry of the hydration shell of the fully hydrated Mg(2+) ion is recognized by the side-chain carboxylate groups in the selectivity filter. This is in contrast to the K(+)-selective filter of KcsA, which recognizes a dehydrated K(+) ion. Our results further revealed a cation-binding site on the periplasmic side, which regulate channel opening and prevents conduction of near-cognate cations.

  16. Influence of different structured channels of mesoporous silicate on the controlled ibuprofen delivery

    International Nuclear Information System (INIS)

    Gao, Lin; Sun, Jihong; Zhang, Li; Wang, Jinpeng; Ren, Bo

    2012-01-01

    The bimodal mesoporous silicas with short random mesoporous channels and MCM-41 with long ordered mesopores were synthesised and modified with 3-(2-aminoethylamino) propyltrimethoxysilane as ibuprofen carriers to study the influence of mesoporous structure on drug delivery property. For further comparing the different mesoporous channels, modified SBA-15 with relative large and long ordered mesopores was also synthesized as drug carriers. The resultant samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, N 2 adsorption–desorption isotherms, thermogravimetric analyses, solid-state 29 Si NMR spectra, elemental analysis, and UV–vis spectra. Meanwhile, the Korsmeyer–Peppas equation f t = kt n was employed to analyze the drug release profile and three release mediums including simulated fluid solution, distilled water and simulated gastric fluid were used. The results indicated that the modified BMMs with the bimodal mesopores leaded to the most drug loading amount of 25.0 mg/0.1 g, while the MCM-41 with the long and one-dimensional mesopores had the least loading amount around 20.3 mg/0.1 g. Meanwhile, the easier diffusion behavior of drug molecules in the bimodal mesopore channels of BMMs resulted in relatively faster drug release properties in comparison with MCM-41, while the release time maintained in SBF for about 12 h (release percent was about 90 wt%) and corresponding release constant k obtained from Korsmeyer–Peppas equation was around 4.10. Highlights: ► BMMs, MCM-41 and SBA-15 with different mesostructure channels were modified with amino groups via post-treatment procedure. ► Loading and release profiles of ibuprofen in modified BMMs, MCM-41 and SBA-15. ► BMMs presents more drug loading amount than MCM-41 as well as better controlled release than SBA-15.

  17. Influence of different structured channels of mesoporous silicate on the controlled ibuprofen delivery

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Lin [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China); Sun, Jihong, E-mail: jhsun@bjut.edu.cn [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China); Zhang, Li; Wang, Jinpeng; Ren, Bo [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China)

    2012-08-15

    The bimodal mesoporous silicas with short random mesoporous channels and MCM-41 with long ordered mesopores were synthesised and modified with 3-(2-aminoethylamino) propyltrimethoxysilane as ibuprofen carriers to study the influence of mesoporous structure on drug delivery property. For further comparing the different mesoporous channels, modified SBA-15 with relative large and long ordered mesopores was also synthesized as drug carriers. The resultant samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, N{sub 2} adsorption-desorption isotherms, thermogravimetric analyses, solid-state {sup 29}Si NMR spectra, elemental analysis, and UV-vis spectra. Meanwhile, the Korsmeyer-Peppas equation f{sub t} = kt{sup n} was employed to analyze the drug release profile and three release mediums including simulated fluid solution, distilled water and simulated gastric fluid were used. The results indicated that the modified BMMs with the bimodal mesopores leaded to the most drug loading amount of 25.0 mg/0.1 g, while the MCM-41 with the long and one-dimensional mesopores had the least loading amount around 20.3 mg/0.1 g. Meanwhile, the easier diffusion behavior of drug molecules in the bimodal mesopore channels of BMMs resulted in relatively faster drug release properties in comparison with MCM-41, while the release time maintained in SBF for about 12 h (release percent was about 90 wt%) and corresponding release constant k obtained from Korsmeyer-Peppas equation was around 4.10. Highlights: Black-Right-Pointing-Pointer BMMs, MCM-41 and SBA-15 with different mesostructure channels were modified with amino groups via post-treatment procedure. Black-Right-Pointing-Pointer Loading and release profiles of ibuprofen in modified BMMs, MCM-41 and SBA-15. Black-Right-Pointing-Pointer BMMs presents more drug loading amount than MCM-41 as well as better controlled release than SBA-15.

  18. ASIC and ENaC type sodium channels: conformational states and the structures of the ion selectivity filters.

    Science.gov (United States)

    Hanukoglu, Israel

    2017-02-01

    The acid-sensing ion channels (ASICs) and epithelial sodium channels (ENaC) are members of a superfamily of channels that play critical roles in mechanosensation, chemosensation, nociception, and regulation of blood volume and pressure. These channels look and function like a tripartite funnel that directs the flow of Na + ions into the cytoplasm via the channel pore in the membrane. The subunits that form these channels share a common structure with two transmembrane segments (TM1 and TM2) and a large extracellular part. In most vertebrates, there are five paralogous genes that code for ASICs (ASIC1-ASIC5), and four for ENaC subunits alpha, beta, gamma, and delta (α, β, γ, and δ). While ASICs can form functional channels as a homo- or heterotrimer, ENaC functions as an obligate heterotrimer composed of α-β-γ or β-γ-δ subunits. The structure of ASIC has been determined in several conformations, including desensitized and open states. This review presents a comparison of the structures of these states using easy-to-understand molecular models of the full complex, the central tunnel that includes an outer vestibule, the channel pore, and ion selectivity filter. The differences in the secondary, tertiary, and quaternary structures of the states are summarized to pinpoint the conformational changes responsible for channel opening. Results of site-directed mutagenesis studies of ENaC subunits are examined in light of ASIC1 models. Based on these comparisons, a molecular model for the selectivity filter of ENaC is built by in silico mutagenesis of an ASIC1 structure. These models suggest that Na + ions pass through the filter in a hydrated state. © 2016 Federation of European Biochemical Societies.

  19. Expression of transient receptor potential channels in the ependymal cells of the developing rat brain.

    Science.gov (United States)

    Jo, Kwang Deog; Lee, Kyu-Seok; Lee, Won Taek; Hur, Mi-Sun; Kim, Ho-Jeong

    2013-03-01

    Cerebrospinal fluid (CSF) plays an important role in providing brain tissue with a stable internal environment as well as in absorbing mechanical and thermal stresses. From its initial composition, derived from the amniotic fluid trapped by the closure of neuropores, CSF is modified by developing and differentiating ependymal cells lining the ventricular surface or forming the choroid plexus. Its osmolarity and ionic composition brings about a change through the action of many channels expressed on the ependymal cells. Some newly discovered transient receptor potential (TRP) channels are known to be expressed in the choroid plexus ependyma. To detect additional TRP channel expression, immunohistochemical screening was performed at the choroid plexus of 13-, 15-, 17-, and 19-day embryos, using antibodies against TRPV1, TRPV3, and TRPA1, and the expression was compared with those in the adult TRP channels. The level of TRP channel expression was higher in the choroid plexus which suggests more active functioning of TRP channels in the developing choroid plexus than the ventricular lining ependyma in the 15- and 17-day embryos. All the expression of TRP channels decreased at the 19th day of gestation. TRPA1 was expressed at a higher level than TRPV1 and TRPV3 in almost all stages in both the choroid plexus and ventricular lining epithelium. The highest level of TRPV1 and TRPV3 expression was observed in association with the glycogen deposits in the cytoplasm of the choroid plexus ependymal cells of the 15- and 17-day embryos.

  20. Structural insights into binding of STAC proteins to voltage-gated calcium channels

    Science.gov (United States)

    Wong King Yuen, Siobhan M.; Campiglio, Marta; Tung, Ching-Chieh

    2017-01-01

    Excitation–contraction (EC) coupling in skeletal muscle requires functional and mechanical coupling between L-type voltage-gated calcium channels (CaV1.1) and the ryanodine receptor (RyR1). Recently, STAC3 was identified as an essential protein for EC coupling and is part of a group of three proteins that can bind and modulate L-type voltage-gated calcium channels. Here, we report crystal structures of tandem-SH3 domains of different STAC isoforms up to 1.2-Å resolution. These form a rigid interaction through a conserved interdomain interface. We identify the linker connecting transmembrane repeats II and III in two different CaV isoforms as a binding site for the SH3 domains and report a crystal structure of the complex with the STAC2 isoform. The interaction site includes the location for a disease variant in STAC3 that has been linked to Native American myopathy (NAM). Introducing the mutation does not cause misfolding of the SH3 domains, but abolishes the interaction. Disruption of the interaction via mutations in the II–III loop perturbs skeletal muscle EC coupling, but preserves the ability of STAC3 to slow down inactivation of CaV1.2. PMID:29078335

  1. Amorphous Oxide Thin Film Transistors with Nitrogen-Doped Hetero-Structure Channel Layers

    Directory of Open Access Journals (Sweden)

    Haiting Xie

    2017-10-01

    Full Text Available The nitrogen-doped amorphous oxide semiconductor (AOS thinfilm transistors (TFTs with double-stacked channel layers (DSCL were prepared and characterized. The DSCL structure was composed of nitrogen-doped amorphous InGaZnO and InZnO films (a-IGZO:N/a-IZO:N or a-IZO:N/a-IGZO:N and gave the corresponding TFT devices large field-effect mobility due to the presence of double conduction channels. The a-IZO:N/a-IGZO:N TFTs, in particular, showed even better electrical performance (µFE = 15.0 cm2・V−1・s−1, SS = 0.5 V/dec, VTH = 1.5 V, ION/IOFF = 1.1 × 108 and stability (VTH shift of 1.5, −0.5 and −2.5 V for positive bias-stress, negative bias-stress, and thermal stress tests, respectively than the a-IGZO:N/a-IZO:N TFTs. Based on the X-ray photoemission spectroscopy measurements and energy band analysis, we assumed that the optimized interface trap states, the less ambient gas adsorption, and the better suppression of oxygen vacancies in the a-IZO:N/a-IGZO:N hetero-structures might explain the better behavior of the corresponding TFTs.

  2. Wavelet Analysis on Turbulent Structure in Drag-Reducing Channel Flow Based on Direct Numerical Simulation

    Directory of Open Access Journals (Sweden)

    Xuan Wu

    2013-01-01

    Full Text Available Direct numerical simulation has been performed to study a polymer drag-reducing channel flow by using a discrete-element model. And then, wavelet analyses are employed to investigate the multiresolution characteristics of velocity components based on DNS data. Wavelet decomposition is applied to decompose velocity fluctuation time series into ten different frequency components including approximate component and detailed components, which show more regular intermittency and burst events in drag-reducing flow. The energy contribution, intermittent factor, and intermittent energy are calculated to investigate characteristics of different frequency components. The results indicate that energy contributions of different frequency components are redistributed by polymer additives. The energy contribution of streamwise approximate component in drag-reducing flow is up to 82%, much more than 25% in the Newtonian flow. Feature of turbulent multiscale structures is shown intuitively by continuous wavelet transform, verifying that turbulent structures become much more regular in drag-reducing flow.

  3. Spontaneous formation of structurally diverse membrane channel architectures from a single antimicrobial peptide

    Science.gov (United States)

    Wang, Yukun; Chen, Charles H.; Hu, Dan; Ulmschneider, Martin B.; Ulmschneider, Jakob P.

    2016-11-01

    Many antimicrobial peptides (AMPs) selectively target and form pores in microbial membranes. However, the mechanisms of membrane targeting, pore formation and function remain elusive. Here we report an experimentally guided unbiased simulation methodology that yields the mechanism of spontaneous pore assembly for the AMP maculatin at atomic resolution. Rather than a single pore, maculatin forms an ensemble of structurally diverse temporarily functional low-oligomeric pores, which mimic integral membrane protein channels in structure. These pores continuously form and dissociate in the membrane. Membrane permeabilization is dominated by hexa-, hepta- and octamers, which conduct water, ions and small dyes. Pores form by consecutive addition of individual helices to a transmembrane helix or helix bundle, in contrast to current poration models. The diversity of the pore architectures--formed by a single sequence--may be a key feature in preventing bacterial resistance and could explain why sequence-function relationships in AMPs remain elusive.

  4. Seeking structural specificity: direct modulation of pentameric ligand-gated ion channels by alcohols and general anesthetics.

    Science.gov (United States)

    Howard, Rebecca J; Trudell, James R; Harris, R Adron

    2014-01-01

    Alcohols and other anesthetic agents dramatically alter neurologic function in a wide range of organisms, yet their molecular sites of action remain poorly characterized. Pentameric ligand-gated ion channels, long implicated in important direct effects of alcohol and anesthetic binding, have recently been illuminated in renewed detail thanks to the determination of atomic-resolution structures of several family members from lower organisms. These structures provide valuable models for understanding and developing anesthetic agents and for allosteric modulation in general. This review surveys progress in this field from function to structure and back again, outlining early evidence for relevant modulation of pentameric ligand-gated ion channels and the development of early structural models for ion channel function and modulation. We highlight insights and challenges provided by recent crystal structures and resulting simulations, as well as opportunities for translation of these newly detailed models back to behavior and therapy.

  5. Glu-Trp-ONa or its acylated analogue (R-Glu-Trp-ONa) administration enhances the wound healing in the model of chronic skin wounds in rabbits

    Science.gov (United States)

    Shevtsov, Maxim A; Smagina, Larisa V; Kudriavtceva, Tatiana A; Petlenko, Sergey V; Voronkina, Irina V

    2015-01-01

    The management of chronic skin wounds represents a major therapeutic challenge. The synthesized dipeptide (Glu-Trp-ONa) and its acylated analogue (R-Glu-Trp-ONa) were assessed in the model of nonhealing dermal wounds in rabbits in relation to their healing properties in wound closure. Following wound modeling, the rabbits received a course of intraperitoneal injections of Glu-Trp-ONa or R-Glu-Trp-ONa. Phosphate-buffered saline and Solcoseryl® were applied as negative and positive control agents, respectively. An injection of Glu-Trp-ONa and R-Glu-Trp-ONa decreased the period of wound healing in animals in comparison to the control and Solcoseryl-treated groups. Acylation of Glu-Trp-ONa proved to be beneficial as related to the healing properties of the dipeptide. Subsequent zymography analyses showed that the applied peptides decreased the proteolytic activity of matrix metalloproteinases MMP-9, MMP-8, and MMP-2 in the early inflammatory phase and reversely increased the activity of MMP-9, MMP-8, and MMP-1 in the remodeling phase. Histological analyses of the wound sections (hematoxylin–eosin, Mallory’s staining) confirmed the enhanced formation of granulation tissue and re-epithelialization in the experimental groups. By administering the peptides, wound closures increased significantly through the modulation of the MMPs’ activity, indicating their role in wound healing. PMID:25848208

  6. Folding Dynamics of the Trp-Cage Miniprotein: Evidence for a Native-Like Intermediate from Combined Time-Resolved Vibrational Spectroscopy and Molecular Dynamics Simulations

    NARCIS (Netherlands)

    Meuzelaar, H.; Marino, K.A.; Huerta-Viga, A.; Panman, M.R.; Smeenk, L.E.J.; Kettelarij, A.J.; van Maarseveen, J.H.; Timmerman, P.; Bolhuis, P.G.; Woutersen, S.

    2013-01-01

    Trp-cage is a synthetic 20-residue miniprotein which folds rapidly and spontaneously to a well-defined globular structure more typical of larger proteins. Due to its small size and fast folding, it is an ideal model system for experimental and theoretical investigations of protein folding

  7. Structural model for dihydropyridine binding to L-type calcium channels.

    Science.gov (United States)

    Tikhonov, Denis B; Zhorov, Boris S

    2009-07-10

    1,4-Dihydropyridines (DHPs) constitute a major class of ligands for L-type Ca(2+) channels (LTCC). The DHPs have a boat-like, six-membered ring with an NH group at the stern, an aromatic moiety at the bow, and substituents at the port and starboard sides. Various DHPs exhibit antagonistic or agonistic activities, which were previously explained as stabilization or destabilization, respectively, of the closed activation gate by the portside substituents. Here we report a novel structural model in which agonist and antagonist activities are determined by different parts of the DHP molecule and have different mechanisms. In our model, which is based on Monte Carlo minimizations of DHP-LTCC complexes, the DHP moieties at the stern, bow, and starboard form H-bonds with side chains of the key DHP-sensing residues Tyr_IIIS6, Tyr_IVS6, and Gln_IIIS5, respectively. We propose that these H-bonds, which are common for agonists and antagonists, stabilize the LTCC conformation with the open activation gate. This explains why both agonists and antagonists increase probability of the long lasting channel openings and why even partial disruption of the contacts eliminates the agonistic action. In our model, the portside approaches the selectivity filter. Hydrophobic portside of antagonists may induce long lasting channel closings by destabilizing Ca(2+) binding to the selectivity filter glutamates. Agonists have either hydrophilic substituents or a hydrogen atom at their portside, and thus lack this destabilizing effect. The predicted orientation of the DHP core allows accommodation of long substituents in the domain interface or in the inner pore. Our model may be useful for developing novel clinically relevant LTCC blockers.

  8. Structural Model for Dihydropyridine Binding to L-type Calcium Channels*

    Science.gov (United States)

    Tikhonov, Denis B.; Zhorov, Boris S.

    2009-01-01

    1,4-Dihydropyridines (DHPs) constitute a major class of ligands for L-type Ca2+ channels (LTCC). The DHPs have a boat-like, six-membered ring with an NH group at the stern, an aromatic moiety at the bow, and substituents at the port and starboard sides. Various DHPs exhibit antagonistic or agonistic activities, which were previously explained as stabilization or destabilization, respectively, of the closed activation gate by the portside substituents. Here we report a novel structural model in which agonist and antagonist activities are determined by different parts of the DHP molecule and have different mechanisms. In our model, which is based on Monte Carlo minimizations of DHP-LTCC complexes, the DHP moieties at the stern, bow, and starboard form H-bonds with side chains of the key DHP-sensing residues Tyr_IIIS6, Tyr_IVS6, and Gln_IIIS5, respectively. We propose that these H-bonds, which are common for agonists and antagonists, stabilize the LTCC conformation with the open activation gate. This explains why both agonists and antagonists increase probability of the long lasting channel openings and why even partial disruption of the contacts eliminates the agonistic action. In our model, the portside approaches the selectivity filter. Hydrophobic portside of antagonists may induce long lasting channel closings by destabilizing Ca2+ binding to the selectivity filter glutamates. Agonists have either hydrophilic substituents or a hydrogen atom at their portside, and thus lack this destabilizing effect. The predicted orientation of the DHP core allows accommodation of long substituents in the domain interface or in the inner pore. Our model may be useful for developing novel clinically relevant LTCC blockers. PMID:19416978

  9. High-Temperature unfolding of a trp-Cage mini-protein: a molecular dynamics simulation study

    Directory of Open Access Journals (Sweden)

    Seshasayee Aswin Sai Narain

    2005-03-01

    Full Text Available Abstract Background Trp cage is a recently-constructed fast-folding miniprotein. It consists of a short helix, a 3,10 helix and a C-terminal poly-proline that packs against a Trp in the alpha helix. It is known to fold within 4 ns. Results High-temperature unfolding molecular dynamics simulations of the Trp cage miniprotein have been carried out in explicit water using the OPLS-AA force-field incorporated in the program GROMACS. The radius of gyration (Rg and Root Mean Square Deviation (RMSD have been used as order parameters to follow the unfolding process. Distributions of Rg were used to identify ensembles. Conclusion Three ensembles could be identified. While the native-state ensemble shows an Rg distribution that is slightly skewed, the second ensemble, which is presumably the Transition State Ensemble (TSE, shows an excellent fit. The denatured ensemble shows large fluctuations, but a Gaussian curve could be fitted. This means that the unfolding process is two-state. Representative structures from each of these ensembles are presented here.

  10. A Mathematica package for calculation of planar channeling radiation spectra of relativistic electrons channeled in a diamond-structure single crystal (quantum approach)

    Science.gov (United States)

    Azadegan, B.

    2013-03-01

    The presented Mathematica code is an efficient tool for simulation of planar channeling radiation spectra of relativistic electrons channeled along major crystallographic planes of a diamond-structure single crystal. The program is based on the quantum theory of channeling radiation which has been successfully applied to study planar channeling at electron energies between 10 and 100 MeV. Continuum potentials for different planes of diamond, silicon and germanium single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the one-dimensional Schrödinger equation. The code is designed to calculate the electron wave functions, transverse electron states in the planar continuum potential, transition energies, line widths of channeling radiation and depth dependencies of the population of quantum states. Finally the spectral distribution of spontaneously emitted channeling radiation is obtained. The simulation of radiation spectra considerably facilitates the interpretation of experimental data. Catalog identifier: AEOH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 446 No. of bytes in distributed program, including test data, etc.: 209805 Distribution format: tar.gz Programming language: Mathematica. Computer: Platforms on which Mathematica is available. Operating system: Operating systems on which Mathematica is available. RAM: 1 MB Classification: 7.10. Nature of problem: Planar channeling radiation is emitted by relativistic charged particles during traversing a single crystal in direction parallel to a crystallographic plane. Channeling is modeled as the motion

  11. Vertical structure of extreme currents in the Faroe-Bank Channel

    Directory of Open Access Journals (Sweden)

    C. Carollo

    2005-09-01

    Full Text Available Extreme currents are studied with the aim of understanding their vertical and spatial structures in the Faroe-Bank Channel. Acoustic Doppler Current Profiler time series recorded in 3 deployments in this channel were investigated. To understand the main features of extreme events, the measurements were separated into their components through filtering and tidal analysis before applying the extreme value theory to the surge component. The Generalized Extreme Value (GEV distribution and the Generalized Pareto Distribution (GPD were used to study the variation of surge extremes from near-surface to deep waters. It was found that this component alone is not able to explain the extremes measured in total currents, particularly below 500 m. Here the mean residual flow enhanced by tidal rectification was found to be the component feature dominating extremes. Therefore, it must be taken into consideration when applying the extreme value theory, not to underestimate the return level for total currents. Return value speeds up to 250 cm s–1 for 50/250 years return period were found for deep waters, where the flow is constrained by the topography at bearings near 300/330° It is also found that the UK Meteorological Office FOAM model is unable to reproduce either the magnitude or the form for the extremes, perhaps due to its coarse vertical and horizontal resolution, and is thus not suitable to model extremes on a regional scale. Keywords. Oceanography: Physical (Currents; General circulation; General or miscellaneous

  12. Vertical structure of extreme currents in the Faroe-Bank Channel

    Directory of Open Access Journals (Sweden)

    C. Carollo

    2005-09-01

    Full Text Available Extreme currents are studied with the aim of understanding their vertical and spatial structures in the Faroe-Bank Channel. Acoustic Doppler Current Profiler time series recorded in 3 deployments in this channel were investigated. To understand the main features of extreme events, the measurements were separated into their components through filtering and tidal analysis before applying the extreme value theory to the surge component. The Generalized Extreme Value (GEV distribution and the Generalized Pareto Distribution (GPD were used to study the variation of surge extremes from near-surface to deep waters. It was found that this component alone is not able to explain the extremes measured in total currents, particularly below 500 m. Here the mean residual flow enhanced by tidal rectification was found to be the component feature dominating extremes. Therefore, it must be taken into consideration when applying the extreme value theory, not to underestimate the return level for total currents. Return value speeds up to 250 cm s–1 for 50/250 years return period were found for deep waters, where the flow is constrained by the topography at bearings near 300/330° It is also found that the UK Meteorological Office FOAM model is unable to reproduce either the magnitude or the form for the extremes, perhaps due to its coarse vertical and horizontal resolution, and is thus not suitable to model extremes on a regional scale.

    Keywords. Oceanography: Physical (Currents; General circulation; General or miscellaneous

  13. Structure-activity studies on 1,4-dihydropyridine calcium channel antagonists and activators

    Energy Technology Data Exchange (ETDEWEB)

    Joslyn, A.F.

    1986-01-01

    Four series of 1,4-dihydropyridine Ca{sup 2+} channel antagonists related to mifedipine were synthesized by a modified Hantzsch procedure to determine the effects of ester (C{sub 3} = CO{sub 2}Me, C{sub 5} = CO{sub 2}R) and phenyl (C{sub 4}) substituents on pharmacological and radioligand binding ((H)nitrendipine) activities in guinea pig ileal longitudinal smooth muscle. Two series of Ca{sup 2+} channel activator 1,4-dihydropyridines, BAY K 8644 (C{sub 3} = NO{sub 2}, C{sub 5} = CO{sub 2}Me) and CGP 28392 (C{sub 2,3} = lactone, C{sub 5} = CO{sub 2}Me) were biochemically evaluated by inhibition of ({sup 3}H)nitrendipine binding in guinea pig ileal longitudinal smooth muscle membranes to establish fundamental structure-activity requirements. A homologous series of bis-1,4-dihydropyridines were synthesized, pharmacologically and biochemically evaluated in an attempt to explore the distribution of the 1,4-dihydropyridine receptor in guinea pig ileal longitudinal smooth muscle membranes. Several potential affinity labels including ester substituted 3- and 4-fluorosulfonyl benzoyl and isothiocyanate derivatives were synthesized and evaluated by inhibition of ({sup 3}H)nitrendipine binding.

  14. Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G. (WU-MED); (Vienna)

    2016-08-15

    Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL-) with a distinct second site is required for high PIP2sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2sensitivity, even in the absence of PL-. Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP2(2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL-binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP2site and explaining the positive allostery between PL-binding and PIP2sensitivity.

  15. Structural characterization of the mechanosensitive channel candidate MCA2 from Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Hideki Shigematsu

    Full Text Available Mechanosensing in plants is thought to be governed by sensory complexes containing a Ca²⁺-permeable, mechanosensitive channel. The plasma membrane protein MCA1 and its paralog MCA2 from Arabidopsis thaliana are involved in mechanical stress-induced Ca²⁺ influx and are thus considered as candidates for such channels or their regulators. Both MCA1 and MCA2 were functionally expressed in Sf9 cells using a baculovirus system in order to elucidate their molecular natures. Because of the abundance of protein in these cells, MCA2 was chosen for purification. Purified MCA2 in a detergent-solubilized state formed a tetramer, which was confirmed by chemical cross-linking. Single-particle analysis of cryo-electron microscope images was performed to depict the overall shape of the purified protein. The three-dimensional structure of MCA2 was reconstructed at a resolution of 26 Å from 5,500 particles and appears to comprise a small transmembrane region and large cytoplasmic region.

  16. Solution NMR structure of the V27A drug resistant mutant of influenza A M2 channel

    International Nuclear Information System (INIS)

    Pielak, Rafal M.; Chou, James J.

    2010-01-01

    Research highlights: → This paper reports the structure of the V27A drug resistant mutant of the M2 channel of influenza A virus. → High quality NMR data allowed a better-defined structure for the C-terminal region of the M2 channel. → Using the structure, we propose a proton transfer pathway during M2 proton conduction. → Structural comparison between the wildtype, V27A and S31N variants allowed an in-depth analysis of possible modes of drug resistance. → Distinct feature of the V27A channel pore also provides an explanation for its faster rate of proton conduction. -- Abstract: The M2 protein of influenza A virus forms a proton-selective channel that is required for viral replication. It is the target of the anti-influenza drugs, amantadine and rimantadine. Widespread drug resistant mutants, however, has greatly compromised the effectiveness of these drugs. Here, we report the solution NMR structure of the highly pathogenic, drug resistant mutant V27A. The structure reveals subtle structural differences from wildtype that maybe linked to drug resistance. The V27A mutation significantly decreases hydrophobic packing between the N-terminal ends of the transmembrane helices, which explains the looser, more dynamic tetrameric assembly. The weakened channel assembly can resist drug binding either by destabilizing the rimantadine-binding pocket at Asp44, in the case of the allosteric inhibition model, or by reducing hydrophobic contacts with amantadine in the pore, in the case of the pore-blocking model. Moreover, the V27A structure shows a substantially increased channel opening at the N-terminal end, which may explain the faster proton conduction observed for this mutant. Furthermore, due to the high quality NMR data recorded for the V27A mutant, we were able to determine the structured region connecting the channel domain to the C-terminal amphipathic helices that was not determined in the wildtype structure. The new structural data show that the

  17. Channel estimation for space-time trellis coded-OFDM systems based on nonoverlapping pilot structure

    CSIR Research Space (South Africa)

    Sokoya, O

    2008-09-01

    Full Text Available The performance of space time trellis coded orthogonal frequency division multiplexing (STTC-OFDM) systems relies on accurate channel state information at the receiver for proper decoding. One method of obtaining channel state information...

  18. A novel reduced-complexity group detection structure in MIMO frequency selective fading channels

    KAUST Repository

    Qaraqe, Khalid A.

    2010-09-01

    In this paper a novel reduced complexity detection method named modified symbol flipping method is introduced and its advantages on reducing the burden of the calculations at the receiver compared to the optimum maximum likelihood detection method on multiple input- multiple output frequency selective fading channels are explained. The initial concept of the symbol flipping method is derived from a preliminary detection scheme named bit flipping which was introduced in [1]. The detection structure employed in this paper is ing, detection, and cancellation. On the detection stage, the proposed method is employed and the results are compared to the group maximum likelihood detection scheme proposed in [2]. Simulation results show that a 6 dB performance gain can be achieved at the expense of a slight increase in complexity in comparison with the conventional symbol flipping scheme. © 2010 Crown.

  19. RBS channeling measurement of damage annealing in InAs/AlSb HEMT structures

    International Nuclear Information System (INIS)

    Hallén, Anders; Moschetti, Giuseppe

    2014-01-01

    Electrical isolation of InAs/AlSb high electron mobility transistors has been achieved by the ion implantation isolation technique. The multilayered structures are grown by molecular beam epitaxy on GaAs substrates. The optimal isolation is provided by damaging patterned areas by 100 keV Ar ions implanted at room temperature using fluence of 2 × 10 15 cm −2 , and then annealing the samples in 365 °C for 30 min. The damage build-up and annealing is studied by channeling Rutherford backscattering spectrometry (RBS) and compared to sheet resistance measurements. Only a low level of damage annealing can be seen in RBS for the post-implant annealed samples, but for Ar fluence higher than 2 × 10 14 cm −2 , a strong electrical resistivity increase can still be achieved

  20. RBS channeling measurement of damage annealing in InAs/AlSb HEMT structures

    Energy Technology Data Exchange (ETDEWEB)

    Hallén, Anders, E-mail: ahallen@kth.se [KTH Royal Institute of Technology, ICT, P.O. Box Electrum 229, SE 164 40 Kista (Sweden); Moschetti, Giuseppe [Chalmers University of Technology, Microtechnology and Nanoscience-MC2, SE-412 96 Gothenburg (Sweden)

    2014-08-01

    Electrical isolation of InAs/AlSb high electron mobility transistors has been achieved by the ion implantation isolation technique. The multilayered structures are grown by molecular beam epitaxy on GaAs substrates. The optimal isolation is provided by damaging patterned areas by 100 keV Ar ions implanted at room temperature using fluence of 2 × 10{sup 15} cm{sup −2}, and then annealing the samples in 365 °C for 30 min. The damage build-up and annealing is studied by channeling Rutherford backscattering spectrometry (RBS) and compared to sheet resistance measurements. Only a low level of damage annealing can be seen in RBS for the post-implant annealed samples, but for Ar fluence higher than 2 × 10{sup 14} cm{sup −2}, a strong electrical resistivity increase can still be achieved.

  1. Crustal and Mantle Structure Beneath the Iles Eparses (Mozambique Channel, Indian Ocean)

    Science.gov (United States)

    Barruol, G.; Fontaine, F. R.; Davy, C.; Schlindwein, V. S. N.; Sigloch, K.

    2014-12-01

    In order to investigate the lithospheric structure of the Mozambique channel (Indian Ocean), we deployed 5 broadband three-components seismic stations between April 2011 and January 2014 on the Islands of Europa (EURO), Juan de Nova (JNOV), Mayotte (MAYO), and Glorieuses (GLOR) in the Mozambique channel and on Tromelin Island (TROM) located ca. 450 km east of Madagascar. We performed measurements of teleseismic shear wave splitting using SKS and SKKS phases and receiver function analyses to characterize the nature and thickness of the crust and the underlying upper mantle structure. Seismic anisotropy is observed at all seismic stations and display a rather homogeneous pattern: average values of the splitting parameters show fast polarization trending between N112°E (EURO) and N120°E (JNOV) to N81°E (MAYO). Observed delay times vary between 0.8 (JNOV) and 1.0 s (MAYO). In Mayotte, analysis of individual backazimuthal variation of splitting parameters suggests an upper mantle more complex than a single anisotropic layer. Station TROM located on Tromelin Island shows similar fast polarization azimuth of N123°E but slightly higher delay time (1.4 s). Fast polarization directions are compared with values predicted by drag-induced anisotropy and absolute plate motion direction and with lithospheric fossil spreading directions. Results are also compared to orientation predicted by large-scale mantle convection models. Receiver functions observations and modelling of P-to-S conversions at the Mohorovičić (Moho) discontinuity have been employed to investigate the variations in the Moho depth, the nature of the crust and of the crust-mantle transition. Preliminary results suggest a Moho depth of 16 km beneath Europa Island.

  2. Structural basis of slow activation gating in the cardiac IKs channel complex

    DEFF Research Database (Denmark)

    Strutz-Seebohm, Nathalie; Pusch, Michael; Wolf, Steffen

    2011-01-01

    of the voltage sensor domain S4 of KCNQ1 in a putative pre-open channel state. Formation of this state may induce slow activation gating, the pivotal characteristic of native cardiac I(Ks) channels. This new KCNQ1-KCNE1 model may become useful for dynamic modeling of disease-associated mutant I(Ks) channels....

  3. Differential Effects of TRPA and TRPV Channels on Behaviors of

    Directory of Open Access Journals (Sweden)

    Jennifer Thies

    2016-01-01

    Full Text Available TRPA and TRPV ion channels are members of the transient receptor potential (TRP cation channel superfamily, which mediates various sensory transductions. In Caenorhabditis elegans , the TRPV channels are known to affect chemosensation, while the TRPA-1 channel is associated with thermosensation and mechanosensation. We examined thermosensation, chemosensation, and osmosensation in strains lacking TRPA-1 or TRPV channels. We found that TRPV channel knockout worms exhibited similar behavioral deficits associated with thermotaxis as the TRPA-1 channel knockout, suggesting a dual role for TRPV channels. In contrast, chemosensation responses, assessed by both avoidance reversal behavior and NaCl osmosensation, were dependent on TRPV channels but seemed independent of TRPA-1 channel. Our findings suggest that, in addition to TRPA-1 channel, TRPV channels are necessary for thermotaxis and may activate, or modulate, the function of TRPA-1 channels. In contrast, TRPA-1 channels do not have a dual responsibility, as they have no functional role in odorant avoidance or osmosensation.

  4. Complex metrology on 3D structures using multi-channel OCD

    Science.gov (United States)

    Kagalwala, Taher; Mahendrakar, Sridhar; Vaid, Alok; Isbester, Paul K.; Cepler, Aron; Kang, Charles; Yellai, Naren; Sendelbach, Matthew; Ko, Mihael; Ilgayev, Ovadia; Katz, Yinon; Tamam, Lilach; Osherov, Ilya

    2017-03-01

    Device scaling has not only driven the use of measurements on more complex structures, in terms of geometry, materials, and tighter ground rules, but also the need to move away from non-patterned measurement sites to patterned ones. This is especially of concern for very thin film layers that have a high thickness dependence on structure geometry or wafer pattern factor. Although 2-dimensional (2D) sites are often found to be sufficient for process monitoring and control of very thin films, sometimes 3D sites are required to further simulate structures within the device. The measurement of film thicknesses only a few atoms thick on complex 3D sites, however, are very challenging. Apart from measuring thin films on 3D sites, there is also a critical need to measure parameters on 3D sites, which are weak and less sensitive for OCD (Optical Critical Dimension) metrology, with high accuracy and precision. Thus, state-ofthe-art methods are needed to address such metrology challenges. This work introduces the concept of Enhanced OCD which uses various methods to improve the sensitivity and reduce correlations for weak parameters in a complex measurement. This work also describes how more channels of information, when used correctly, can improve the precision and accuracy of weak, non-sensitive or complex parameters of interest.

  5. Simulations of the Pore Structures for a M2GlyR Derived Channel Forming Peptide in Different Membrane Environments

    Science.gov (United States)

    Al-Rawi, A.; Herrera, A.; Tomich, J.; Rahman, T.

    2007-03-01

    As part of an effort to develop a peptide-based compound suitable for clinical use as a channel replacement therapeutic for treating channelopathies such as cystic fibrosis, we present a reductionist model that appears to grasp the characteristics of ion channeling peptides. In particular we present the observed changes in the functional characteristics of NK4-M2GlyR p22 (KKKKPARVGLGITTVLTMTTQS), a M2 GlyR derived channel forming peptide. Starting with a structure determined by multidimensional NMR (800 MHz) in SDS, a potential from CHARMM force-field was used to relax the structure of NK4-M2GlyR p22. Following the relaxation, numerous pore structures were generated for the symmetric five-helix assembly with geometries varying from cylindrical to conical. As it is difficult a priori to assign accurately the orientation of the hydrophilic portion of M2GlyR derived amphipath towards the inside of the pore, we tilted and rotated the helical structure by five different angles about the backbone axis before forming the pore. Energy minimization of the channel was performed in vacuum, in phosphotidylcholine (POPC) membrane, and 60% POPC 30% phosphotidylethanolamine (POPE) in order to determine the effect of the environment surrounding on the structure on its energy minimization. We will present the various pore assemblies, in the different membrane environments, used to predict the most probably membrane bound structure.

  6. The role of transient receptor potential channels in metabolic syndrome

    DEFF Research Database (Denmark)

    Liu, Daoyan; Zhu, Zhiming; Tepel, Martin

    2008-01-01

    Metabolic syndrome is correlated with increased cardiovascular risk and characterized by several factors, including visceral obesity, hypertension, insulin resistance, and dyslipidemia. Several members of a large family of nonselective cation entry channels, e.g., transient receptor potential (TRP......) canonical (TRPC), vanilloid (TRPV), and melastatin (TRPM) channels, have been associated with the development of cardiovascular diseases. Thus, disruption of TRP channel expression or function may account for the observed increased cardiovascular risk in metabolic syndrome patients. TRPV1 regulates...... adipogenesis and inflammation in adipose tissues, whereas TRPC3, TRPC5, TRPC6, TRPV1, and TRPM7 are involved in vasoconstriction and regulation of blood pressure. Other members of the TRP family are involved in regulation of insulin secretion, lipid composition, and atherosclerosis. Although...

  7. Structural models of the transmembrane region of voltage-gated and other K+ channels in open, closed, and inactivated conformations.

    Science.gov (United States)

    Durell, S R; Hao, Y; Guy, H R

    1998-01-01

    A large collaborative, multidisciplinary effort involving many research laboratories continues which uses indirect methods of molecular biology and membrane biophysics to analyze the three-dimensional structures and functional mechanisms of K+ channels. This work also extends to the distant relatives of these channels, including the voltage-gated Na+ and Ca2+ channels. The role that our group plays in this process is to combine the information gained from experimental studies with molecular modeling techniques to generate atomic-scale structural models of these proteins. The modeling process involves three stages which are summarized as: (I) prediction of the channel sequence transmembrane topology, including the functionality and secondary structure of the segments; (II) prediction of the relative positions of the transmembrane segments, and (III) filling in all atoms of the amino acid residues, with conformations for energetically stabilized interactions. Both physiochemical and evolutionary principles (including sequence homology analysis) are used to guide the development. In addition to testing the steric and energetic feasibilities of different structural hypotheses, the models provide guidance for the design of new experiments. Structural modeling also serves to "fill in the gaps" of experimental data, such as predicting additional residue interactions and conformational changes responsible for functional processes. The modeling process is currently at the stage that experimental studies have definitely confirmed most of our earlier predictions about the transmembrane topology and functionality of different segments. Additionally, this report describes the detailed, three-dimensional models we have developed for the entire transmembrane region and important functional sites of the voltage-gated Shaker K+ channel in the open, closed, and inactivated conformations (including the ion-selective pore and voltage-sensor regions). As part of this effort, we also

  8. Distribution of the Trp64Arg polymorphism in the ß 3-adrenergic receptor gene in athletes and its influence on cardiovascular function.

    Science.gov (United States)

    Kim, Sung Min; Oh, Sang Duk; Jung, In Geun; Lee, Jin; Sim, Young Je; Lee, Jae Koo; Kang, Byung Yong

    2010-08-01

    The Trp64Arg polymorphism in the beta₃-adrenergic receptor (beta₃-AR) gene was extensively studied concerning the relationship with cardiovascular (CV) diseases, but few studies addressed this issue in athletes. To examine the relationship between the Trp64Arg polymorphism in the beta₃-AR gene and several CV functions such as cardiac structure and function or blood biochemical parameters in Korean male controls and athletes. We recruited a total of 114 study subjects, including 81 male athletes (8 long distance runners, 17 soccer, 8 baseball, 10 basketball, 8 volleyball, 8 ice hockey, 8 judo, 6 taekwondo and 8 gymnastics) and 33 controls. Two dimensional echocardiography was performed in order to assess the cardiac structure and function and blood biochemical parameters were measured. Genotyping of Trp64Arg polymorphism in the beta₃-AR gene was also performed by the SNaPshot method. The genotype and allele distribution of Trp64Arg polymorphism in the beta₃-AR gene were significantly different among each sporting discipline, showing the highest Arg allele frequency in volleyball and gymnastics (p athletes only (p athletes. However, further studies of the precise mechanism behind these associations are needed.

  9. Crystal Structure of the Mammalian GIRK2 K+ Channel and Gating Regulation by G-Proteins, PIP2 and Sodium

    Science.gov (United States)

    Whorton, Matthew R.; MacKinnon, Roderick

    2011-01-01

    Summary G-protein-gated K+ channels (Kir3.1–Kir3.4) control electrical excitability in many different cells. Among their functions relevant to human physiology and disease, they regulate the heart rate and govern a wide range of neuronal activities. Here we present the first crystal structures of a G-protein-gated K+ channel. By comparing the wild-type structure to that of a constitutively active mutant, we identify a global conformational change through which G-proteins could open a G-loop gate in the cytoplasmic domain. The structures of both channels in the absence and presence of PIP2 show that G-proteins open only the G-loop gate in the absence of PIP2, but in the presence of PIP2 the G-loop gate and a second inner helix gate become coupled, so that both gates open. We also identify a strategically located Na+ ion-binding site, which would allow intracellular Na+ to modulate GIRK channel activity. These data provide a mechanistic description of multi-ligand regulation of GIRK channel gating. PMID:21962516

  10. Structure-activity relationship study and discovery of indazole 3-carboxamides as calcium-release activated calcium channel blockers.

    Science.gov (United States)

    Bai, Sha; Nagai, Masazumi; Koerner, Steffi K; Veves, Aristidis; Sun, Lijun

    2017-02-01

    Aberrant activation of mast cells contributes to the development of numerous diseases including cancer, autoimmune disorders, as well as diabetes and its complications. The influx of extracellular calcium via the highly calcium selective calcium-release activated calcium (CRAC) channel controls mast cell functions. Intracellular calcium homeostasis in mast cells can be maintained via the modulation of the CRAC channel, representing a critical point for therapeutic interventions. We describe the structure-activity relationship study (SAR) of indazole-3-carboxamides as potent CRAC channel blockers and their ability to stabilize mast cells. Our SAR results show that the unique regiochemistry of the amide linker is critical for the inhibition of calcium influx, the release of the pro-inflammatory mediators β-hexosaminidase and tumor necrosis factor α by activated mast cells. Thus, the indazole-3-carboxamide 12d actively inhibits calcium influx and stabilizes mast cells with sub-μM IC 50 . In contrast, its reverse amide isomer 9c is inactive in the calcium influx assay even at 100μM concentration. This requirement of the specific 3-carboxamide regiochemistry in indazoles is unprecedented in known CRAC channel blockers. The new structural scaffolds described in this report expand the structural diversity of the CRAC channel blockers and may lead to the discovery of novel immune modulators for the treatment of human diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Structure of the SthK carboxy-terminal region reveals a gating mechanism for cyclic nucleotide-modulated ion channels.

    Directory of Open Access Journals (Sweden)

    Divya Kesters

    Full Text Available Cyclic nucleotide-sensitive ion channels are molecular pores that open in response to cAMP or cGMP, which are universal second messengers. Binding of a cyclic nucleotide to the carboxyterminal cyclic nucleotide binding domain (CNBD of these channels is thought to cause a conformational change that promotes channel opening. The C-linker domain, which connects the channel pore to this CNBD, plays an important role in coupling ligand binding to channel opening. Current structural insight into this mechanism mainly derives from X-ray crystal structures of the C-linker/CNBD from hyperpolarization-activated cyclic nucleotide-modulated (HCN channels. However, these structures reveal little to no conformational changes upon comparison of the ligand-bound and unbound form. In this study, we take advantage of a recently identified prokaryote ion channel, SthK, which has functional properties that strongly resemble cyclic nucleotide-gated (CNG channels and is activated by cAMP, but not by cGMP. We determined X-ray crystal structures of the C-linker/CNBD of SthK in the presence of cAMP or cGMP. We observe that the structure in complex with cGMP, which is an antagonist, is similar to previously determined HCN channel structures. In contrast, the structure in complex with cAMP, which is an agonist, is in a more open conformation. We observe that the CNBD makes an outward swinging movement, which is accompanied by an opening of the C-linker. This conformation mirrors the open gate structures of the Kv1.2 channel or MthK channel, which suggests that the cAMP-bound C-linker/CNBD from SthK represents an activated conformation. These results provide a structural framework for better understanding cyclic nucleotide modulation of ion channels, including HCN and CNG channels.

  12. Enhancement-Mode AlGaN/GaN High Electron Mobility Transistors Using a Nano-Channel Array Structure

    International Nuclear Information System (INIS)

    Liu Sheng-Hou; Cai Yong; Zeng Chun-Hong; Shi Wen-Hua; Zhang Bao-Shun; Gong Ru-Min; Wang Jin-Yan; Wen, Cheng P.; Feng Zhi-Hong; Wang Jing-Jing; Yin Jia-Yun; Qin Hua

    2011-01-01

    A nano-channel array (NCA) structure is applied to realize enhancement-mode (E-mode) AlGaN/GaN high-electron mobility transistors (HEMTs). The fabricated NCA-HEMT, consisting of 1000 channels connected in parallel with a channel width of 64 nm, shows a threshold voltage of 0.15 V and a subthreshold slope of 78 mV/dec, compared to −3.92 V and 99 mV/dec for a conventional HEMT (C-HEMT), respectively Both the NCA-HEMT and C-HEMT show similar gate leakage current, indicating no significant degradation in gate leakage characteristics for the NCA-HEMT. The surrounding-field effect and relieved polarization contribute to the very large positive threshold voltage shift, while the work function difference makes it positive. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Molecular Dynamics Simulation of the Antiamoebin Ion Channel: Linking Structure and Conductance

    Science.gov (United States)

    Wilson, Michael A.; Wei, Chenyu; Bjelkmar, Paer; Wallace, B. A.; Pohorille, Andrew

    2011-01-01

    Molecular dynamics simulations were carried out in order to ascertain which of the potential multimeric forms of the transmembrane peptaibol channel, antiamoebin, is consistant with its measured conductance. Estimates of the conductance obtained through counting ions that cross the channel and by solving the Nernst-Planck equation yield consistent results, indicating that the motion of ions inside the channel can be satisfactorily described as diffusive.The calculated conductance of octameric channels is markedly higher than the conductance measured in single channel recordings, whereas the tetramer appears to be non-conducting. The conductance of the hexamer was estimated to be 115+/-34 pS and 74+/-20 pS, at 150 mV and 75 mV, respectively, in satisfactory agreement with the value of 90 pS measured at 75 mV. On this basis we propose that the antiamoebin channel consists of six monomers. Its pore is large enough to accommodate K(+) and Cl(-) with their first solvation shells intact. The free energy barrier encountered by K(+) is only 2.2 kcal/mol whereas Cl(-) encounters a substantially higher barrier of nearly 5 kcal/mol. This difference makes the channel selective for cations. Ion crossing events are shown to be uncorrelated and follow Poisson statistics. keywords: ion channels, peptaibols, channel conductance, molecular dynamics

  14. Structure and assembly of a trans-periplasmic channel for type IV pili in Neisseria meningitidis.

    Directory of Open Access Journals (Sweden)

    Jamie-Lee Berry

    2012-09-01

    Full Text Available Type IV pili are polymeric fibers which protrude from the cell surface and play a critical role in adhesion and invasion by pathogenic bacteria. The secretion of pili across the periplasm and outer membrane is mediated by a specialized secretin protein, PilQ, but the way in which this large channel is formed is unknown. Using NMR, we derived the structures of the periplasmic domains from N. meningitidis PilQ: the N-terminus is shown to consist of two β-domains, which are unique to the type IV pilus-dependent secretins. The structure of the second β-domain revealed an eight-stranded β-sandwich structure which is a novel variant of the HSP20-like fold. The central part of PilQ consists of two α/β fold domains: the structure of the first of these is similar to domains from other secretins, but with an additional α-helix which links it to the second α/β domain. We also determined the structure of the entire PilQ dodecamer by cryoelectron microscopy: it forms a cage-like structure, enclosing a cavity which is approximately 55 Å in internal diameter at its largest extent. Specific regions were identified in the density map which corresponded to the individual PilQ domains: this allowed us to dock them into the cryoelectron microscopy density map, and hence reconstruct the entire PilQ assembly which spans the periplasm. We also show that the C-terminal domain from the lipoprotein PilP, which is essential for pilus assembly, binds specifically to the first α/β domain in PilQ and use NMR chemical shift mapping to generate a model for the PilP:PilQ complex. We conclude that passage of the pilus fiber requires disassembly of both the membrane-spanning and the β-domain regions in PilQ, and that PilP plays an important role in stabilising the PilQ assembly during secretion, through its anchorage in the inner membrane.

  15. Bipolar phospholipid sensing by TRPC5 calcium channel.

    Science.gov (United States)

    Beech, D J

    2007-02-01

    TRPC5 [TRP (transient receptor potential) canonical (or classical) 5] is a widely expressed mammalian homologue of Drosophila TRP, forming a calcium- and sodium-permeable channel in the plasma membrane either as a homomultimer or heteromultimer with other proteins (e.g. TRPC1). Although several factors are known to stimulate the channel, understanding of its endogenous activators and functions is limited. This paper provides a brief and focused review of our latest findings that show that TRPC5 is a sensor of important signalling phospholipids, including lysophosphatidylcholine and sphingosine 1-phosphate, acting extracellularly or intracellularly. Underlying mechanisms of action and biological relevance are discussed.

  16. Methodology of structural integrity assesment of CANDU-6 NPP fuel channels

    International Nuclear Information System (INIS)

    Radu, Vasile

    2004-01-01

    The paper describes the methodology of assessing the structural integrity in the CANDU-6 fuel channels making use of alternative methods of evaluation. An evaluation of the structural integrity of a CANDU-6 pressure tube made of Zr-2,5%Nb presenting both sharp and blunted defects is done. These analyses are made in compliance with the Canadian guide 'Pressure Tubes Fitness-for-service', and other two Recognizing procedures internationally adopted: the British procedure R6/Rev.4 and the American procedure API 579. Previously, the data base containing the data on materials property as well as the heat and dynamical loads in normal operation in CANDU-6 pressure tubes was established. Obtaining complete diagrams for structural integrity of pressure tubes with sharp and blunted defects in conditions of normal operation and long-term irradiation is the next step of the methodology to be developed. Modelling sharp and blunted defects on the inner side of pressure tubes, which can occur in normal reactor operating conditions is achieved by means of capabilities of pre-processing of two finite element analysis codes namely FEA-Crack and FEA-Flaw. The second part of the work deals with the analyses by finite element method of the fracture mechanics by means of the FEA-Crack code and with the evaluation of sharp and blunted defects by FAD diagrams in compliance with the British procedure R6/Rev.4. For typical models of blunted defects and thermo-mechanical loads specific to normal operation finite element analyses by FEA-Flaw codes were performed. Then FAD-iDHC diagrams were constructed to evaluate the initiation of the slow cracking under hydrogen/deuterium absorption, the known phenomenon of delayed hydride cracking (DHC)

  17. Impact of water temperature and structural parameters on the hydraulic labyrinth-channel emitter performance

    Directory of Open Access Journals (Sweden)

    Ahmed I. Al-Amoud

    2014-06-01

    Full Text Available The effects of water temperature and structural parameters of a labyrinth emitter on drip irrigation hydraulic performance were investigated. The inside structural parameters of the trapezoidal labyrinth emitter include path width (W and length (L, trapezoidal unit numbers (N, height (H, and spacing (S. Laboratory experiments were conducted using five different types of labyrinth-channel emitters (three non-pressure compensating and two pressure-compensating emitters commonly used for subsurface drip irrigation systems. The water temperature effect on the hydraulic characteristics at various operating pressures was recorded and a comparison was made to identify the most effective structural parameter on emitter performance. The pressure compensating emitter flow exponent (x average was 0.014, while non-pressure compensating emitter’s values average was 0.456, indicating that the sensitivity of non-pressure compensating emitters to pressure variation is an obvious characteristic (p<0.001 of this type of emitters. The effects of water temperature on emitter flow rate were insignificant (p>0.05 at various operating pressures, where the flow rate index values for emitters were around one. The effects of water temperature on manufacturer’s coefficient of variation (CV values for all emitters were insignificant (p>0.05. The CV values of the non-pressure compensating emitters were lower than those of pressure compensating emitters. This is typical for most compensating models because they are manufactured with more elements than non-compensating emitters are. The results of regression analysis indicate that N and H are the essential factors (p<0.001 to affect the hydraulic performance.

  18. Glu-Trp-ONa or its acylated analogue (R-Glu-Trp-ONa administration enhances the wound healing in the model of chronic skin wounds in rabbits

    Directory of Open Access Journals (Sweden)

    Shevtsov MA

    2015-03-01

    Full Text Available Maxim A Shevtsov,1,2 Larisa V Smagina,1 Tatiana A Kudriavtceva,3 Sergey V Petlenko,4 Irina V Voronkina1 1Institute of Cytology of the Russian Academy of Sciences (RAS, St Petersburg, Russia; 2IP Pavlov State Medical University of St Petersburg, St Petersburg, Russia; 3Institute of Experimental Medicine of the North-West Branch of the Russian Academy of Medical Sciences (IEM NWB RAMS, St Petersburg, Russia; 4Military Medical Academy, St Petersburg, Russia Abstract: The management of chronic skin wounds represents a major therapeutic challenge. The synthesized dipeptide (Glu-Trp-ONa and its acylated analogue (R-Glu-Trp-ONa were assessed in the model of nonhealing dermal wounds in rabbits in relation to their healing properties in wound closure. Following wound modeling, the rabbits received a course of intraperitoneal injections of Glu-Trp-ONa or R-Glu-Trp-ONa. Phosphate-buffered saline and Solcoseryl® were applied as negative and positive control agents, respectively. An injection of Glu-Trp-ONa and R-Glu-Trp-ONa decreased the period of wound healing in animals in comparison to the control and Solcoseryl-treated groups. Acylation of Glu-Trp-ONa proved to be beneficial as related to the healing properties of the dipeptide. Subsequent zymography analyses showed that the applied peptides decreased the proteolytic activity of matrix metalloproteinases MMP-9, MMP-8, and MMP-2 in the early inflammatory phase and reversely increased the activity of MMP-9, MMP-8, and MMP-1 in the remodeling phase. Histological analyses of the wound sections (hematoxylin–eosin, Mallory’s staining confirmed the enhanced formation of granulation tissue and re-epithelialization in the experimental groups. By administering the peptides, wound closures increased significantly through the modulation of the MMPs’ activity, indicating their role in wound healing. Keywords: chronic wound, matrix metalloproteinases, small peptides

  19. Structural and functional characteristics of natural and constructed channels draining a reclaimed mountaintop removal and valley fill coal mine

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining has altered the landscape of the Central Appalachian region in the United States. The goals of this study were to 1) compare the structure and function of natural and constructed stream channels in forested and MTR/VF catch...

  20. Histidine 352 (His352 and tryptophan 355 (Trp355 are essential for flax UGT74S1 glucosylation activity toward secoisolariciresinol.

    Directory of Open Access Journals (Sweden)

    Kaushik Ghose

    Full Text Available Flax secoisolariciresinol diglucoside (SDG lignan is a natural phytoestrogen for which a positive role in metabolic diseases is emerging. Until recently however, much less was known about SDG and its monoglucoside (SMG biosynthesis. Lately, flax UGT74S1 was identified and characterized as an enzyme sequentially glucosylating secoisolariciresinol (SECO into SMG and SDG when expressed in yeast. However, the amino acids critical for UGT74S1 glucosyltransferase activity were unknown. A 3D structural modeling and docking, site-directed mutagenesis of five amino acids in the plant secondary product glycosyltransferase (PSPG motif, and enzyme assays were conducted. UGT74S1 appeared to be structurally similar to the Arabidopsis thaliana UGT72B1 model. The ligand docking predicted Ser357 and Trp355 as binding to the phosphate and hydroxyl groups of UDP-glucose, whereas Cys335, Gln337 and Trp355 were predicted to bind the 7-OH, 2-OCH3 and 17-OCH3 of SECO. Site-directed mutagenesis of Cys335, Gln337, His352, Trp355 and Ser357, and enzyme assays revealed an alteration of these binding sites and a significant reduction of UGT74S1 glucosyltransferase catalytic activity towards SECO and UDP-glucose in all mutants. A complete abolition of UGT74S1 activity was observed when Trp355 was substituted to Ala355 and Gly355 or when changing His352 to Asp352, and an altered metabolite profile was observed in Cys335Ala, Gln337Ala, and Ser357Ala mutants. This study provided for the first time evidence that Trp355 and His352 are critical for UGT74S1's glucosylation activity toward SECO and suggested the possibility for SMG production in vitro.

  1. Structure and hibernation-associated expression of the transient receptor potential vanilloid 4 channel (TRPV4) mRNA in the Japanese grass lizard (Takydromus tachydromoides).

    Science.gov (United States)

    Nagai, Kazuya; Saitoh, Yasushi; Saito, Shigeru; Tsutsumi, Ken-ichi

    2012-03-01

    Animals possess systems for sensing environmental temperature using temperature-sensitive ion channels called transient receptor potential channels (TRPs). Various TRPs have been identified and characterized in mammals. However, those of ectotherms, such as reptiles, are less well studied. Here, we identify the V subfamily of TRP (TRPV) in two reptile species: Japanese grass lizard (Takydromus tachydromoides) and Japanese four-lined ratsnake (Elaphe quadrivirgata). Phylogenetic analysis of TRPVs indicated that ectothermic reptilian TRPVs are more similar to those of endothermic chicken and mammals, than to other ectotherms, such as frog and fish. Expression analysis of TRPV4 mRNA in the lizard showed that its expression in tissues and organs is specifically controlled in cold environments and hibernation. The mRNA was ubiquitously expressed in seven tissues/organs examined. Both cold-treatment and hibernation lowered TRPV4 expression, but in a tissue/organ-specific manner. Cold-treatment reduced TRPV4 expression in tongue and muscle, while in hibernation it was reduced more widely in brain, tongue, heart, lung, and muscle. Interestingly, however, levels of TRPV4 mRNA in the skin remained unaffected after entering hibernation and cold-treatment, implying that TRPV4 in the skin may act as an environmental temperature sensor throughout the reptilian life cycle, including hibernation. This is the first report, to our knowledge, to describe reptilian TRPV4 in relation to hibernation.

  2. Probing the structure-function relationship of alpha-latrotoxin-formed channels with antibodies and pronase.

    Science.gov (United States)

    Chanturiya, A N; Nikolaenko, A N; Shatursky OYa; Lishko, V K

    1996-10-01

    The major toxic component of black widow spider (Latrodectus mactans tredecimguttatus) venom, alpha-latrotoxin, is known to form ionic channels in different membranes. In order to probe the extramembrane domains of alpha-latrotoxin molecule, alpha-latrotoxin channels in planar lipid membrane were treated with antibodies to latrotoxin or with pronase added to different sides of the membrane. It was found that antibody addition to the same side as the toxin (cis) decreased channel conductance only at positive potentials across the membrane. In contrast, trans side addition of antibodies changed the channel conductance at both positive and negative potentials: at positive potential conductance first slightly increased then decreased by more then 50%; at negative potential it decreased much more quickly, to only about 20% of the initial value. No dependence on membrane potential was found for pronase treatment of incorporated channels. For both cis and trans application of pronase, channel selectivity for Ca2+, Mg2+, Ba2+ and K+, Na+, Li+ ions did not change significantly but Cd2+ block was decreased. Trans pronase treatment also resulted in some rectification of I/V curves and an increase in channel conductance. We interpret these findings as evidence that alpha-latrotoxin channel has protruding parts on both sides of the membrane and that its conformation in the membrane depends on membrane potential.

  3. Altimetric signal and three-dimensional structure of the sea in the Channel of Sicily

    Science.gov (United States)

    Nardelli, Bruno Buongiorno; Santoleri, Rosalia; Iudicone, Daniele; Zoffoli, Simona; Marullo, Salvatore

    1999-09-01

    The 1996 Altimeter/Synoptic Mesoscale Plancton Experiment (ALT/SYMPLEX) was specifically designed to perform in situ measurements simultaneous with the passage of TOPEX/POSEIDON (T/P) and ERS 2 over selected tracks in the central and eastern Sicily Channel. This experiment made it possible to have, for the first time, a validation of altimetry with in situ data over the Mediterranean, where weak dynamics results in a modest sea elevation, rarely exceeding 10 cm. Historical infrared and altimetric satellite data were first analyzed in order to study the variability of the circulation in the area. The comparative and integrative analysis of simultaneous satellite data and in situ measurements permitted investigation of the relation between the altimeter-derived surface topography and the three-dimensional structure of the sea. The Pearson correlation coefficients between altimeter data and dynamic heights along track resulted to be 0.72-0.89 (T/P) and 0.88 (ERS 2) when using conventional repeat track analysis. For T/P, a correlation value of 0.87 was found for time differences computed basing on a collinear analysis technique. This analysis also led to the identification of a strong barotropic component of the velocity field located near the Sicilian continental shelf, where it is responsible for approximately 60% of the signal.

  4. Effect of back-pressure forcing on shock train structures in rectangular channels

    Science.gov (United States)

    Gnani, F.; Zare-Behtash, H.; White, C.; Kontis, K.

    2018-04-01

    The deceleration of a supersonic flow to the subsonic regime inside a high-speed engine occurs through a series of shock waves, known as a shock train. The generation of such a flow structure is due to the interaction between the shock waves and the boundary layer inside a long and narrow duct. The understanding of the physics governing the shock train is vital for the improvement of the design of high-speed engines and the development of flow control strategies. The present paper analyses the sensitivity of the shock train configuration to a back-pressure variation. The complex characteristics of the shock train at an inflow Mach number M = 2 in a channel of constant height are investigated with two-dimensional RANS equations closed by the Wilcox k-ω turbulence model. Under a sinusoidal back-pressure variation, the simulated results indicate that the shock train executes a motion around its mean position that deviates from a perfect sinusoidal profile with variation in oscillation amplitude, frequency, and whether the pressure is first increased or decreased.

  5. Endurance degradation and lifetime model of p-channel floating gate flash memory device with 2T structure

    Science.gov (United States)

    Wei, Jiaxing; Liu, Siyang; Liu, Xiaoqiang; Sun, Weifeng; Liu, Yuwei; Liu, Xiaohong; Hou, Bo

    2017-08-01

    The endurance degradation mechanisms of p-channel floating gate flash memory device with two-transistor (2T) structure are investigated in detail in this work. With the help of charge pumping (CP) measurements and Sentaurus TCAD simulations, the damages in the drain overlap region along the tunnel oxide interface caused by band-to-band (BTB) tunneling programming and the damages in the channel region resulted from Fowler-Nordheim (FN) tunneling erasure are verified respectively. Furthermore, the lifetime model of endurance characteristic is extracted, which can extrapolate the endurance degradation tendency and predict the lifetime of the device.

  6. Conformation of cyclo-(Gln-Trp-Phe-{beta}Ala-Leu-Met), a NK-2 tachykinin receptor antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jong Myung [Silla Univ., Pusan (Korea, Republic of)

    1999-10-01

    Solution conformation of cyclo-(Gln-Trp-Phe-{beta}Ala-Leu-Met), new NK-2 antagonist in dimethyl sulfoxide solution, has been determined by the use of two-dimensional nuclear magnetic resonance spectroscopy combined with simulated annealing calculations. The peptide exhibited converged structures with the atomic root-mean-square difference for the backbone atoms (N, C{sup a}, C') of all residues being 0.02A in the 25 annealed structures. The analysis of the structures indicated that the cyclic peptide has three intramolecular hydrogen bonds between Met NH and {beta}Ala CO, {beta}Ala NH and Met CO, Phe NH and Met CO, and contain a type-I {beta}-turn with Gln and Trp and a {gamma}-turn with Leu. The addition of an extra methylene group to Gly, i.e. {beta}-Ala residue, may relax some unfavorable restraints in the cyclic backbone structure, hence enabling an additional hydrogen bond, which results in stabilizing one conformation.

  7. TRP channels: a missing bond in the entrainment mechanism of peripheral clocks throughout evolution

    OpenAIRE

    Poletini, Maristela O; Moraes, Maria Nath?lia; Ramos, Bruno C?sar; Jer?nimo, Rodrigo; Castrucci, Ana Maria de Lauro

    2015-01-01

    Circadian rhythm may be understood as a temporal organization that works to orchestrate physiological processes and behavior in a period of approximately 24?h. Because such temporal organization has evolved in the presence of predictable environmental clues, such as day length, tides, seasons, and temperature, the organism has confronted the natural selection in highly precise intervals of opportunities and risks, generating temporal programs and resetting mechanisms, which are well conserved...

  8. Simulations of the pore structures for a M2G1yR derived channel forming peptide in membrane

    Science.gov (United States)

    Al-Rawi, Ahlam N.; Al-Rawi, Asma; Chen, Jianhan; Herrera, Alvaro; Tomich, John; Rahman, Talat S.

    2008-03-01

    In an effort to develop a peptide-based compound suitable for clinical use as a channel replacement therapeutic for treating channelopathies such as cystic fibrosis, we present a reductionist model that appears to capture many of the biophysical properties of an intact ion channel using short channel-forming peptides. We have developed two anion selective channel-forming peptides with near native and altered properties from the peptides derived from the glycine receptor: NK4-M2GlyR-p22 WT (KKKKPAR-VGLGITTVLTMTTQS) and NK4-M2GlyR-p22 S22W (KKKKPARVGLGITTVLTMTTQW), respectively. Starting with the two structures determined by solution multidimensional NMR (800 MHz) in SDS, we used CHARMM and NAMD to perform molecular dynamics simulations on the monomers. Using the existing experimental data, we then built an initial 5- helix assembly by altering the tilted angle, rotational angle and pore radius. We investigated the impact of the single mutation at position 22 on the structure and dynamics of the pore formed in a membrane build in a hydrated POPC lipid bilayer. Probable structures for both assemblies are presented.

  9. Rectified motion in an asymmetrically structured channel due to induced-charge electrokinetic and thermo-kinetic phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Sugioka, Hideyuki, E-mail: hsugioka@shinshu-u.ac.jp [Frontier Research Center, Canon Inc. 30-2, Shimomaruko 3-chome, Ohta-ku, Tokyo 146-8501, Japan and Department of Mechanical Systems Engineering, Shinshu University 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2016-02-15

    It would be advantageous to move fluid by the gradient of random thermal noises that are omnipresent in the natural world. To achieve this motion, we propose a rectifier that uses a thermal noise along with induced-charge electroosmosis and electrophoresis (ICEO and ICEP) around a metal post cylinder in an asymmetrically structured channel and numerically examine its rectification performance. By the boundary element method combined with the thin double layer approximation, we find that rectified motion occurs in the asymmetrically structured channel due to ICEO and ICEP. Further, by thermodynamical and equivalent circuit methods, we discuss a thermal voltage that drives a rectifier consisting of a fluidic channel of an electrolyte and an impedance as a noise source. Our calculations show that fluid can be moved in the asymmetrically structured channel by the fluctuation of electric fields due to a thermal noise only when there is a temperature difference. In addition, our simple noise argument provides a different perspective for the thermo-kinetic phenomena (around a metal post) which was predicted based on the electrolyte Seebeck effect in our previous paper [H. Sugioka, “Nonlinear thermokinetic phenomena due to the Seebeck effect,” Langmuir 30, 8621 (2014)].

  10. UV-induced tandem double mutations in the trpA gene of E. coli

    International Nuclear Information System (INIS)

    Piechocki, R.; Langhammer, R.

    1980-01-01

    The ultraviolet light induction of tandem double mutations in a reverse mutation system was shown using trpA mutants which are characterized by the codon sequences GAA and AAG in codon position 211. Among 597 Trp + independent revertants of the trpA (AAG211) strain 3 full revertants were detected arising from UV-induced tandem double base exchanges. In the codon unit 211 full revertants due to single base exchanges are at least 20 times as frequent as full revertants due to tandem double base exchanges. (author)

  11. Crystal Structure of 12-Lipoxygenase Catalytic-Domain-Inhibitor Complex Identifies a Substrate-Binding Channel for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shu; Mueser, Timothy C.; Marnett, Lawrence J.; Funk, Jr., Max O. (Toledo); (Vanderbilt)

    2014-10-02

    Lipoxygenases are critical enzymes in the biosynthesis of families of bioactive lipids including compounds with important roles in the initiation and resolution of inflammation and in associated diseases such as diabetes, cardiovascular disease, and cancer. Crystals diffracting to high resolution (1.9 {angstrom}) were obtained for a complex between the catalytic domain of leukocyte 12-lipoxygenase and the isoform-specific inhibitor, 4-(2-oxapentadeca-4-yne)phenylpropanoic acid (OPP). In the three-dimensional structure of the complex, the inhibitor occupied a new U-shaped channel open at one end to the surface of the protein and extending past the redox-active iron site that is essential for catalysis. In models, the channel accommodated arachidonic acid, defining the binding site for the substrate of the catalyzed reaction. There was a void adjacent to the OPP binding site connecting to the surface of the enzyme and providing a plausible access channel for the other substrate, oxygen.

  12. Flow structure and channel morphology at a natural confluent meander bend

    Science.gov (United States)

    Riley, James D.; Rhoads, Bruce L.

    2012-08-01

    Previous experimental, field, and modeling studies of confluence dynamics have focused mainly on junctions formed by straight channels. In contrast, natural rivers often meander and tributaries can enter meandering rivers on the outside of bends to form a junction planform known as a confluent meander bend. In this study, field measurements of three-dimensional velocity components and bed topography at a confluent meander bend reveal a complex hydrodynamic environment that responds to changes in momentum-flux ratio, while channel morphology remains relatively stable. Flow from the tributary deflects high-velocity flow and helical motion in the curving main river toward the inside of the bend, inducing bed scour and inhibiting point-bar development. The high junction angle forces the tributary flow to abruptly realign to the orientation of the downstream channel, initiating a counter-rotating helical cell over the outer portion of the bend. Two surface-convergent helical cells persist through the downstream channel, where the combined flows accelerate as the channel cross-sectional area is constricted by a bar along the downstream junction corner, precluding flow separation. Long-term stability of its planform suggests that this confluent meander bend represents a quasi-stable channel configuration. Overall, patterns of flow and channel morphology are quite different from typical patterns in most meander bends, but are generally consistent with a conceptual model of confluent meander bends derived from previous laboratory experiments and numerical modeling.

  13. Contribution of large-scale coherent structures towards the cross flow in two interconnected channels

    International Nuclear Information System (INIS)

    Mahmood, A.; Rohde, M.; Hagen, T.H.J.J. van der; Mudde, R.F.

    2009-01-01

    Single phase cross flow through a gap region joining two vertical channels has been investigated experimentally for Reynolds numbers, based on the channels hydraulic diameter, ranging from 850 to 21000. The flow field in the gap region is investigated by 2D-PIV and the inter channel mass transfer is quantified by the tracer injection method. Experiments carried out for variable gap heights and shape show the existence of a street of large-scale counter rotating vortices on either side of the channel-gap interface, resulting from the mean velocity gradient in the gap and the main channel region. The appearance of the coherent vortices is subject to a threshold associated with the difference between the maximum and the minimum average stream wise velocities in the channel and the gap region, respectively. The auto power spectral density of the cross velocity component in the gap region exhibits a slope of -3 in the inertial range, indicating the 2D nature of these vortices. The presence of the large-scale vortices enhances the mass transfer through the gap region by approximately 63% of the mass transferred by turbulent mixing alone. The inter-channel mass transfer, due to cross flow, is found to be dependent not only on the large-scale vortices characteristics, but also on the gap geometry. (author)

  14. CRISPR/Cas9-Mediated Trp53 and Brca2 Knockout to Generate Improved Murine Models of Ovarian High-Grade Serous Carcinoma.

    Science.gov (United States)

    Walton, Josephine; Blagih, Julianna; Ennis, Darren; Leung, Elaine; Dowson, Suzanne; Farquharson, Malcolm; Tookman, Laura A; Orange, Clare; Athineos, Dimitris; Mason, Susan; Stevenson, David; Blyth, Karen; Strathdee, Douglas; Balkwill, Frances R; Vousden, Karen; Lockley, Michelle; McNeish, Iain A

    2016-10-15

    There is a need for transplantable murine models of ovarian high-grade serous carcinoma (HGSC) with regard to mutations in the human disease to assist investigations of the relationships between tumor genotype, chemotherapy response, and immune microenvironment. In addressing this need, we performed whole-exome sequencing of ID8, the most widely used transplantable model of ovarian cancer, covering 194,000 exomes at a mean depth of 400× with 90% exons sequenced >50×. We found no functional mutations in genes characteristic of HGSC (Trp53, Brca1, Brca2, Nf1, and Rb1), and p53 remained transcriptionally active. Homologous recombination in ID8 remained intact in functional assays. Further, we found no mutations typical of clear cell carcinoma (Arid1a, Pik3ca), low-grade serous carcinoma (Braf), endometrioid (Ctnnb1), or mucinous (Kras) carcinomas. Using CRISPR/Cas9 gene editing, we modeled HGSC by generating novel ID8 derivatives that harbored single (Trp53 -/- ) or double (Trp53 -/- ;Brca2 -/- ) suppressor gene deletions. In these mutants, loss of p53 alone was sufficient to increase the growth rate of orthotopic tumors with significant effects observed on the immune microenvironment. Specifically, p53 loss increased expression of the myeloid attractant CCL2 and promoted the infiltration of immunosuppressive myeloid cell populations into primary tumors and their ascites. In Trp53 -/- ;Brca2 -/- mutant cells, we documented a relative increase in sensitivity to the PARP inhibitor rucaparib and slower orthotopic tumor growth compared with Trp53 -/- cells, with an appearance of intratumoral tertiary lymphoid structures rich in CD3 + T cells. This work validates new CRISPR-generated models of HGSC to investigate its biology and promote mechanism-based therapeutics discovery. Cancer Res; 76(20); 6118-29. ©2016 AACR. ©2016 American Association for Cancer Research.

  15. Englerin A Agonizes the TRPC4/C5 Cation Channels to Inhibit Tumor Cell Line Proliferation.

    Directory of Open Access Journals (Sweden)

    Cheryl Carson

    Full Text Available Englerin A is a structurally unique natural product reported to selectively inhibit growth of renal cell carcinoma cell lines. A large scale phenotypic cell profiling experiment (CLiP of englerin A on ¬over 500 well characterized cancer cell lines showed that englerin A inhibits growth of a subset of tumor cell lines from many lineages, not just renal cell carcinomas. Expression of the TRPC4 cation channel was the cell line feature that best correlated with sensitivity to englerin A, suggesting the hypothesis that TRPC4 is the efficacy target for englerin A. Genetic experiments demonstrate that TRPC4 expression is both necessary and sufficient for englerin A induced growth inhibition. Englerin A induces calcium influx and membrane depolarization in cells expressing high levels of TRPC4 or its close ortholog TRPC5. Electrophysiology experiments confirmed that englerin A is a TRPC4 agonist. Both the englerin A induced current and the englerin A induced growth inhibition can be blocked by the TRPC4/C5 inhibitor ML204. These experiments confirm that activation of TRPC4/C5 channels inhibits tumor cell line proliferation and confirms the TRPC4 target hypothesis generated by the cell line profiling. In selectivity assays englerin A weakly inhibits TRPA1, TRPV3/V4, and TRPM8 which suggests that englerin A may bind a common feature of TRP ion channels. In vivo experiments show that englerin A is lethal in rodents near doses needed to activate the TRPC4 channel. This toxicity suggests that englerin A itself is probably unsuitable for further drug development. However, since englerin A can be synthesized in the laboratory, it may be a useful chemical starting point to identify novel modulators of other TRP family channels.

  16. Acid-sensing ion channel (ASIC) structure and function: Insights from spider, snake and sea anemone venoms.

    Science.gov (United States)

    Cristofori-Armstrong, Ben; Rash, Lachlan D

    2017-12-01

    Acid-sensing ion channels (ASICs) are proton-activated cation channels that are expressed in a variety of neuronal and non-neuronal tissues. As proton-gated channels, they have been implicated in many pathophysiological conditions where pH is perturbed. Venom derived compounds represent the most potent and selective modulators of ASICs described to date, and thus have been invaluable as pharmacological tools to study ASIC structure, function, and biological roles. There are now ten ASIC modulators described from animal venoms, with those from snakes and spiders favouring ASIC1, while the sea anemones preferentially target ASIC3. Some modulators, such as the prototypical ASIC1 modulator PcTx1 have been studied in great detail, while some of the newer members of the club remain largely unstudied. Here we review the current state of knowledge on venom derived ASIC modulators, with a particular focus on their molecular interaction with ASICs, what they have taught us about channel structure, and what they might still reveal about ASIC function and pathophysiological roles. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.' Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Calcium Channels: Structure and Function (Annals of the New York Academy of Sciences. Volume 560)

    Science.gov (United States)

    1989-06-26

    state C into activated closed state A. These transitions can be described by potential- dependent Hodgkin - Huxley kinetics using a square power of the m...with transitions that can be satisfactorily described by the Hodgkin - Huxley model with two charged indepen- dent "gating" particles; channels of...Different Types of Ca Channels. By P. KOSTYUK, N. AKAIKE, YU. OSIPCHUK, A. SAVCHENKO, and Y A . SH UBA

  18. Protein structure and ionic selectivity in calcium channels: Selectivity filter size, not shape, matters

    OpenAIRE

    Malasics, Attila; Gillespie, Dirk; Nonner, Wolfgang; Henderson, Douglas; Eisenberg, Bob; Boda, Dezső

    2009-01-01

    Calcium channels have highly charged selectivity filters (4 COO− groups) that attract cations in to balance this charge and minimize free energy, forcing the cations (Na+ and Ca2+) to compete for space in the filter. A reduced model was developed to better understand the mechanism of ion selectivity in calcium channels. The charge/space competition (CSC) mechanism implies that Ca2+ is more efficient in balancing the charge of the filter because it provides twice the charge as Na+ while occupy...

  19. Molecular analysis of the graviperception signal transduction in the flagellate Euglena gracilis: Involvement of a transient receptor potential-like channel and a calmodulin

    Science.gov (United States)

    Häder, Donat-Peter; Richter, Peter R.; Schuster, Martin; Daiker, Viktor; Lebert, Michael

    2009-04-01

    Euglena gracilis, a unicellular, photosynthetic flagellate is a model system for environmentally controlled behavior responses. The organism shows pronounced negative gravitaxis. This movement is based on physiological mechanisms, which in the past had been only indirectly assessed. It was shown that mechano-sensitive calcium channels are involved in the gravitaxis response. Recent studies have demonstrated that members of the transient receptor potential (TRP) family function as mechano-sensitive channels in several different cell types. We have sequenced part of a TRP gene in Euglena and applied RNA interference (RNAi) to confirm that these channels are involved in graviperception. It was found that RNAi against the putative TRP channel abolished gravitaxis. The genes of three calmodulins were sequences in Euglena, one of which was previously known in its protein structure (cal 1). The other two were unknown (cal 2 and cal 3). Cal 2 has been analyzed in detail. The biosynthesis of the corresponding proteins of cal 1 and cal 2 was inhibited by means of RNA interference to see whether this blockage impairs gravitaxis. RNAi of cal 1 leads to a long-term loss of free swimming in the cells (while euglenoid movement persists). It induced pronounced cell form aberrations and the division of cells was hampered. After recovery from RNAi the cell showed precise negative gravitaxis again. Thus cal 1 does not seem to be involved in gravitaxis. In contrast, the blockage of cal 2 has no pronounced influence on motility and cell form but leads to a complete loss of gravitactic orientation for more than 30 days showing that this calmodulin is an element in the signal transduction chain. The data are discussed in the context of the current model of the gravitaxis signal transduction chain in Euglena gracilis.

  20. Higher cardiorespiratory fitness attenuates the risk of atherosclerosis associated with ADRB3 Trp64Arg polymorphism.

    Science.gov (United States)

    Iemitsu, Motoyuki; Fujie, Shumpei; Murakami, Haruka; Sanada, Kiyoshi; Kawano, Hiroshi; Gando, Yuko; Kawakami, Ryoko; Tanaka, Noriko; Miyachi, Motohiko

    2014-01-01

    β3-Adrenergic receptor (ADRB3) Trp64Arg polymorphism is associated with atherogenic risk factors that include weight gain, insulin resistance, and diabetes. Habitual exercise brings higher cardiorespiratory fitness and results in the amelioration of atherosclerotic risk factors. However, the effects of cardiorespiratory fitness level and ADRB3 Trp64Arg polymorphism on the risk of cardiovascular disease remain unclear. A cross-sectional investigation of 877 Japanese men and women (18-75 years old) was performed to clarify the effects of cardiorespiratory fitness on the relationship between ADRB3 Trp64Arg polymorphism and risk of cardiovascular disease. Common carotid intima-media thickness (ccIMT) and blood lipid profiles were assessed as surrogate markers of atherosclerosis. We measured peak oxygen uptake (V̇O(2peak)) during incremental cycle ergometer exercise testing. Subjects were divided into groups with high (High-Fit) and low (Low-Fit) levels of cardiorespiratory fitness based on the median value of V̇O(2peak) for sex and decade. Levels of body fat, triglycerides, and plasma glucose were lower and high-density lipoprotein cholesterol levels and V̇O(2peak) were higher in High-Fit subjects than Low-Fit subjects. ADRB3 Trp64Arg polymorphism did not significantly affect ccIMT or blood lipid profiles. In Low-Fit subjects, ccIMT was higher in individuals with the Arg/Arg genotype compared to the Trp/Trp and Trp/Arg genotypes (each P Fit subjects. Higher levels of cardiorespiratory fitness may attenuate the risk of atherosclerosis associated with ADRB3 Trp64Arg polymorphism.

  1. Social influence and adolescent health-related physical activity in structured and unstructured settings: role of channel and type.

    Science.gov (United States)

    Spink, Kevin S; Wilson, Kathleen S; Ulvick, Jocelyn

    2012-08-01

    Social influence channels (e.g., parents) and types (e.g., compliance) have each been related to physical activity independently, but little is known about how these two categories of influence may operate in combination. This study examined the relationships between various combinations of social influence and physical activity among youth across structured and unstructured settings. Adolescents (N=304), classified as high or low active, reported the social influence combinations they received for being active. Participants identified three channels and three types of influence associated with being active. For structured activity, compliance with peers and significant others predicted membership in the high active group (values of psocial influence, when examining health-related physical activity.

  2. Human HDAC isoform selectivity achieved via exploitation of the acetate release channel with structurally unique small molecule inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, Lewis; Dobler, Markus R.; Radetich, Branko; Zhu, Yanyi; Atadja, Peter W.; Claiborne, Tavina; Grob, Jonathan E.; McRiner, Andrew; Pancost, Margaret R.; Patnaik, Anup; Shao, Wenlin; Shultz, Michael; Tichkule, Ritesh; Tommasi, Ruben A.; Vash, Brian; Wang, Ping; Stams, Travis (Novartis)

    2013-11-20

    Herein we report the discovery of a family of novel yet simple, amino-acid derived class I HDAC inhibitors that demonstrate isoform selectivity via access to the internal acetate release channel. Isoform selectivity criteria is discussed on the basis of X-ray crystallography and molecular modeling of these novel inhibitors bound to HDAC8, potentially revealing insights into the mechanism of enzymatic function through novel structural features revealed at the atomic level.

  3. Structure-function relation of phospholamban: modulation of channel activity as a potential regulator of SERCA activity.

    Directory of Open Access Journals (Sweden)

    Serena Smeazzetto

    Full Text Available Phospholamban (PLN is a small integral membrane protein, which binds and inhibits in a yet unknown fashion the Ca(2+-ATPase (SERCA in the sarcoplasmic reticulum. When reconstituted in planar lipid bilayers PLN exhibits ion channel activity with a low unitary conductance. From the effect of non-electrolyte polymers on this unitary conductance we estimate a narrow pore with a diameter of ca. 2.2 Å for this channel. This value is similar to that reported for the central pore in the structure of the PLN pentamer. Hence the PLN pentamer, which is in equilibrium with the monomer, is the most likely channel forming structure. Reconstituted PLN mutants, which either stabilize (K27A and R9C or destabilize (I47A the PLN pentamer and also phosphorylated PLN still generate the same unitary conductance of the wt/non-phosphorylated PLN. However the open probability of the phosphorylated PLN and of the R9C mutant is significantly lower than that of the respective wt/non-phosphorylated control. In the context of data on PLN/SERCA interaction and on Ca(2+ accumulation in the sarcoplasmic reticulum the present results are consistent with the view that PLN channel activity could participate in the balancing of charge during Ca(2+ uptake. A reduced total conductance of the K(+ transporting PLN by phosphorylation or by the R9C mutation may stimulate Ca(2+ uptake in the same way as an inhibition of K(+ channels in the SR membrane. The R9C-PLN mutation, a putative cause of dilated cardiomyopathy, might hence affect SERCA activity also via its inherent low open probability.

  4. Purification and structural study of the voltage-sensor domain of the human KCNQ1 potassium ion channel.

    Science.gov (United States)

    Peng, Dungeng; Kim, Ji-Hun; Kroncke, Brett M; Law, Cheryl L; Xia, Yan; Droege, Kristin D; Van Horn, Wade D; Vanoye, Carlos G; Sanders, Charles R

    2014-04-01

    KCNQ1 (also known as KV7.1 or KVLQT1) is a voltage-gated potassium channel modulated by members of the KCNE protein family. Among multiple functions, KCNQ1 plays a critical role in the cardiac action potential. This channel is also subject to inherited mutations that cause certain cardiac arrhythmias and deafness. In this study, we report the overexpression, purification, and preliminary structural characterization of the voltage-sensor domain (VSD) of human KCNQ1 (Q1-VSD). Q1-VSD was expressed in Escherichia coli and purified into lyso-palmitoylphosphatidylglycerol micelles, conditions under which this tetraspan membrane protein yields excellent nuclear magnetic resonance (NMR) spectra. NMR studies reveal that Q1-VSD shares a common overall topology with other channel VSDs, with an S0 helix followed by transmembrane helices S1-S4. The exact sequential locations of the helical spans do, however, show significant variations from those of the homologous segments of previously characterized VSDs. The S4 segment of Q1-VSD was seen to be α-helical (with no 310 component) and underwent rapid backbone amide H-D exchange over most of its length. These results lay the foundation for more advanced structural studies and can be used to generate testable hypotheses for future structure-function experiments.

  5. Dual curved photonic crystal ring resonator based channel drop filter using two-dimensional photonic crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Chhipa, Mayur Kumar, E-mail: mayurchhipa1@gmail.com [Deptt. of Electronics and Communication Engineering, Government Engineering College Ajmer Rajasthan INDIA (India); Dusad, Lalit Kumar [Rajasthan Technical University Kota, Rajasthan (India)

    2016-05-06

    In this paper channel drop filter (CDF) is designed using dual curved photonic crystal ring resonator (PCRR). The photonic band gap (PBG) is calculated by plane wave expansion (PWE) method and the photonic crystal (PhC) based on two dimensional (2D) square lattice periodic arrays of silicon (Si) rods in air structure have been investigated using finite difference time domain (FDTD) method. The number of rods in Z and X directions is 21 and 20 respectively with lattice constant 0.540 nm and rod radius r = 0.1 µm. The channel drop filter has been optimized for telecommunication wavelengths λ = 1.591 µm with refractive indices 3.533. In the designed structure further analysis is also done by changing whole rods refractive index and it has been observed that this filter may be used for filtering several other channels also. The designed structure is useful for CWDM systems. This device may serve as a key component in photonic integrated circuits. The device is ultra compact with the overall size around 123 µm{sup 2}.

  6. The 2015 Gorkha Earthquake and the Structure of a Himalayan Intracontinental Subduction Channel From Geodesy, Seismicity, and Seismic Imaging

    Science.gov (United States)

    Schulte-Pelkum, V.; Barnhart, W. D.; McNamara, D. E.; Karplus, M. S.; Monsalve, G.

    2017-12-01

    We present early results from a joint geodetic and seismic project that seeks to clarify the structure and behavior of the Main Himalayan Thrust (MHT) and the position and role of the 2015 Gorkha earthquake sequence rupture planes within it. Recent work suggested that aftershocks of the Gorkha sequence outline a 10-15 km thick subduction channel between the Eurasian and Indian plates. Seismic reflections and phase conversions have been attributed to the MHT and interpreted variously as a ductile shear zone with seismic anisotropy or a low-velocity fluid-rich channel. Our ongoing work attempts to precisely locate the mainshock and aftershocks within imaged structure using internally consistent model parameters for geodetic and teleseismic source inversions, aftershock locations, and receiver functions. Our goal is to determine which parts of the subduction zone were seismically active in the 2015 event, to investigate whether the main rupture occurred along the top, along the bottom, or through an imaged low-velocity channel or shear zone, whether shear fabric is present in the hanging wall or in the footwall, and whether a subduction channel is present. We address these questions through a joint seismic-geodetic approach that melds reanalysis of receiver functions from regional broadband seismometers, precise relocation of aftershocks from the 2015 sequence within imaged structure, and geodetic fault slip modeling of the two large Gorkha events. Our approach uses geodetic best-fit tests to these Mw7.8 and 7.3 earthquakes to elucidate a range of candidate source geometries informed from seismically based rupture models, location of aftershocks and structure imaged by receiver functions. We show geodetically constrained rupture models and aftershock seismicity within the previously imaged structure. We present receiver functions from the HICLIMB and NAMASTE temporary networks to test for anisotropic versus low-velocity channel signatures of the MHT, and introduce an

  7. Crystal structure and dynamics of a lipid-induced potential desensitized-state of a pentameric ligand-gated channel

    Energy Technology Data Exchange (ETDEWEB)

    Basak, Sandip [Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, United States; Schmandt, Nicolaus [Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, United States; Gicheru, Yvonne [Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, United States; Chakrapani, Sudha [Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, United States

    2017-03-06

    Desensitization in pentameric ligand-gated ion channels plays an important role in regulating neuronal excitability. Here, we show that docosahexaenoic acid (DHA), a key ω-3 polyunsaturated fatty acid in synaptic membranes, enhances the agonist-induced transition to the desensitized state in the prokaryotic channel GLIC. We determined a 3.25 Å crystal structure of the GLIC-DHA complex in a potentially desensitized conformation. The DHA molecule is bound at the channel-periphery near the M4 helix and exerts a long-range allosteric effect on the pore across domain-interfaces. In this previously unobserved conformation, the extracellular-half of the pore-lining M2 is splayed open, reminiscent of the open conformation, while the intracellular-half is constricted, leading to a loss of both water and permeant ions. These findings, in combination with spin-labeling/EPR spectroscopic measurements in reconstituted-membranes, provide novel mechanistic details of desensitization in pentameric channels.

  8. Effect of Functional Nano Channel Structures Different Widths on Injection Molding and Compression Molding Replication Capabilities

    DEFF Research Database (Denmark)

    Calaon, M.; Tosello, G.; Garnaes, J.

    The present study investigates the capabilities of the two employed processes, injection molding (IM) and injection compression molding (ICM) on replicating different channel cross sections. Statistical design of experiment was adopted to optimize replication quality of produced polymer parts...... with the two different molding technologies. Focus of the experimental work was the assessment of the IM and ICM processes capabilities to replicate different channels widths (240 nm, 440 nm and 1040 nm) at different positions from the gate based on the deviations of their dimensions from the corresponding...

  9. Structural dynamics of soluble chloride intracellular channel protein CLIC1 examined by amide hydrogen-deuterium exchange mass spectrometry.

    Science.gov (United States)

    Stoychev, Stoyan H; Nathaniel, Christos; Fanucchi, Sylvia; Brock, Melissa; Li, Sheng; Asmus, Kyle; Woods, Virgil L; Dirr, Heini W

    2009-09-08

    Chloride intracellular channel protein 1 (CLIC1) functions as an anion channel in plasma and nuclear membranes when its soluble monomeric form converts to an integral-membrane form. The transmembrane region of CLIC1 is located in its thioredoxin-like domain 1, but the mechanism whereby the protein converts to its membrane conformation has yet to be determined. Since channel formation in membranes is enhanced at low pH (5 to 5.5), a condition that is found at the surface of membranes, the structural dynamics of soluble CLIC1 was studied at pH 7 and at pH 5.5 in the absence of membranes by amide hydrogen-deuterium exchange mass spectrometry (DXMS). Rapid hydrogen exchange data indicate that CLIC1 displays a similar core structure at these pH values. Domain 1 is less stable than the all-helical domain 2, and, while the structure of domain 1 remains intact, its conformational flexibility is further increased in an acidic environment (pH 5.5). In the absence of membrane, an acidic environment appears to prime the solution structure of CLIC1 by destabilizing domain 1 in order to lower the activation energy barrier for its conversion to the membrane-insertion conformation. The significantly enhanced H/D-exchange rates at pH 5.5 displayed by two segments (peptides 11-31 and 68-82) could be due to the protonation of acidic residues in salt bridges. One of these segments (peptide 11-31) includes part of the transmembrane region which, in the solution structure, consists of helix alpha1. This helix is intrinsically stable and is most likely retained in the membrane conformation. Strand beta2, another element of the transmembrane region, displays a propensity to form a helical structure and has putative N- and C-capping motifs, suggesting that it too most likely forms a helix in a lipid bilayer.

  10. Ehrlichia chaffeensis TRP32 Nucleomodulin Function and Localization Is Regulated by NEDD4L-Mediated Ubiquitination

    Directory of Open Access Journals (Sweden)

    Tierra R. Farris

    2018-01-01

    Full Text Available Ehrlichia chaffeensis is an obligately intracellular bacterium that reprograms the mononuclear phagocyte through diverse effector-host interactions to modulate various host cell processes. In a previous study, we reported that the E. chaffeensis nucleomodulin TRP32 regulates transcription of host genes in several biologically relevant categories, including cell differentiation and proliferation. In this study, we investigate the effect of ubiquitination on TRP32 function and localization within the host cell. TRP32 is both mono- and polyubiquitinated on multiple lysine residues during infection and when ectopically expressed. Despite lacking a canonical PPxY motif, TRP32 interacted with, and was modified by the human HECT E3 ubiquitin (Ub ligase NEDD4L. TRP32 ubiquitination was not by K48-linked polyUb chains, nor was it degraded by the proteasome; however, TRP32 was modified by K63-linked polyUb chains detected both in the cytosol and nucleus. HECT ligase inhibitor, heclin, altered the subnuclear localization of ectopically expressed TRP32 from a diffuse nuclear pattern to a lacy, punctate pattern with TRP32 distributed around the periphery of the nucleus and nucleoli. When a TRP32 lysine null (K-null mutant was ectopically expressed, it exhibited a similar phenotype as single lysine mutants (K63R, K93R, and K123R. However, the K-null mutant showed increased amounts of cytoplasmic TRP32 compared to single lysine mutants or heclin-treated cells ectopically expressing TRP32. These alterations in localization corresponded to changes in TRP32 transcriptional repressor function with heclin-treated and single lysine mutants unable to repress transcription of a TRP32 target genes in a luciferase assay.

  11. A Common Structural Component for β-Subunit Mediated Modulation of Slow Inactivation in Different KV Channels

    Directory of Open Access Journals (Sweden)

    Nathalie Strutz-Seebohm

    2013-06-01

    Full Text Available Background/Aims: Potassium channels are tetrameric proteins providing potassium selective passage through lipid embedded proteinaceous pores with highest fidelity. The selectivity results from binding to discrete potassium binding sites and stabilization of a hydrated potassium ion in a central internal cavity. The four potassium binding sites, generated by the conserved TTxGYGD signature sequence are formed by the backbone carbonyls of the amino acids TXGYG. Residues KV1.5-Val481, KV4.3-Leu368 and KV7.1- Ile 313 represent the amino acids in the X position of the respective channels. Methods: Here, we study the impact of these residues on ion selectivity, permeation and inactivation kinetics as well as the modulation by β-subunits using site-specific mutagenesis, electrophysiological analyses and molecular dynamics simulations. Results: We identify this position as key in modulation of slow inactivation by structurally dissimilar β-subunits in different KV channels. Conclusion: We propose a model in which structural changes accompanying activation and β-subunit modulation allosterically constrain the backbone carbonyl oxygen atoms via the side chain of the respective X-residue in the signature sequence to reduce conductance during slow inactivation.

  12. A conserved residue cluster that governs kinetics of ATP-dependent gating of Kir6.2 potassium channels

    DEFF Research Database (Denmark)

    Zhang, Roger S; Wright, Jordan; Pless, Stephan Alexander

    2015-01-01

    elements that control the kinetics of ATP-dependent regulation of KATP (Kir6.2 + SUR1) channels using rapid concentration jumps. WT Kir6.2 channels re-open after rapid washout of ATP with a time constant of approximately 60 ms. Extending similar kinetic measurements to numerous mutants revealed fairly...... modest effects on gating kinetics despite significant changes in ATP sensitivity and open probability. However, we identified a pair of highly conserved neighboring amino acids (Trp68, Lys170) that control the rate of channel opening and inhibition in response to ATP. Paradoxically, mutations of Trp68...... or Lys170 markedly slow the kinetics of channel opening (500 ms and 700 ms for Trp68Leu and Lys170Asn, respectively), while increasing channel open probability. Examining the functional effects of these residues using phi-value analysis revealed a steep negative slope. This finding implies...

  13. Diapir versus along-channel ascent of crustal material during plate convergence: constrained by the thermal structure of subduction zones

    Science.gov (United States)

    Liu, M. Q.; Li, Z. H.

    2017-12-01

    Crustal rocks can be subducted to mantle depths, interact with the mantle wedge, and then exhume to the crustal depth again, which is generally considered as the mechanism for the formation of ultrahigh-pressure metamorphic rocks in nature. The crustal rocks undergo dehydration and melting at subarc depths, giving rise to fluids that metasomatize and weaken the overlying mantle wedge. There are generally two ways for the material ascent from subarc depths: one is along subduction channel; the other is through the mantle wedge by diapir. In order to study the conditions and dynamics of these contrasting material ascent modes, systematic petrological-thermo-mechanical numerical models are constructed with variable thicknesses of the overriding and subducting continental plates, ages of the subducting oceanic plate, as well as the plate convergence rates. The model results suggest that the thermal structures of subduction zones control the thermal condition and fluid/melt activity at the slab-mantle interface in subcontinental subduction channels, which further strongly affect the material transportation and ascent mode. Thick overriding continental plate and low-angle subduction style induced by young subducting oceanic plate both contribute to the formation of relatively cold subduction channels with strong overriding mantle wedge, where the along-channel exhumation occurs exclusively to result in the exhumation of HP-UHP metamorphic rocks. In contrast, thin overriding lithosphere and steep subduction style induced by old subducting oceanic plate are the favorable conditions for hot subduction channels, which lead to significant hydration and metasomatism, melting and weakening of the overriding mantle wedge and thus cause the ascent of mantle wedge-derived melts by diapir through the mantle wedge. This may corresponds to the origination of continental arc volcanism from mafic to ultramafic metasomatites in the bottom of the mantle wedge. In addition, the plate

  14. Listeriosis in p47(phox-/-) and TRp55-/- mice: protection despite absence of ROI and susceptibility despite presence of RNI.

    Science.gov (United States)

    Endres, R; Luz, A; Schulze, H; Neubauer, H; Fütterer, A; Holland, S M; Wagner, H; Pfeffer, K

    1997-09-01

    The significance of host defense mechanisms in primary listeriosis in vivo is incompletely understood. Here, we show that tumor necrosis factor receptor p55-/- (TRp55-/-) mice are susceptible to Listeria monocytogenes infection in the presence of leukocyte recruitment, inflammatory cytokine production (including IFNgamma), nitric oxide synthesis, and oxidative burst formation. Mice deficient for oxidative burst (p47[phox-/-] mice) are relatively resistant to listeriosis. Despite activation of these antibacterial effector systems, TRp55-/- phagocytes in vivo are incapable of confining and eradicating L. monocytogenes inside phagolysosomes. Bone marrow chimeras reveal that for eradication of L. monocytogenes, TRp55 is crucially required only on cells from hematopoietic origin. Unexpectedly, prior to death, exocrine pancreatic cells undergo apoptosis in TRp55-/- mice. Collectively, these data demonstrate that in vivo, TRp55 initiates a protective, listericidal mechanism in phagocytes that differs from nitric oxide production and oxidative burst formation and that uncontrolled listeriosis results in necrotizing pancreatitis in TRp55-/- mice.

  15. Structural analysis of erbium {delta}-doped InP by OMVPE with RBS-channeling

    Energy Technology Data Exchange (ETDEWEB)

    Yuhara, Junji; Takeda, Hitoshi; Matsubara, Naoki; Tabuchi, Masao; Fujiwara, Yasufumi; Morita, Kenji; Takeda, Yoshikazu [Nagoya Univ. (Japan). School of Engineering

    1997-03-01

    We have determined the lattice location of Er in InP {delta}-doped by OMVPE with RBS-channeling. Er concentrations along the <001> and <011> directions are same as random yields, while a significant flux peaking effect is seen for the <111> direction. These data suggest that Er atoms occupy the site equivalent to the hexahedral site in InP lattice. (author)

  16. Protein structure and ionic selectivity in calcium channels: selectivity filter size, not shape, matters.

    Science.gov (United States)

    Malasics, Attila; Gillespie, Dirk; Nonner, Wolfgang; Henderson, Douglas; Eisenberg, Bob; Boda, Dezso

    2009-12-01

    Calcium channels have highly charged selectivity filters (4 COO(-) groups) that attract cations in to balance this charge and minimize free energy, forcing the cations (Na(+) and Ca(2+)) to compete for space in the filter. A reduced model was developed to better understand the mechanism of ion selectivity in calcium channels. The charge/space competition (CSC) mechanism implies that Ca(2+) is more efficient in balancing the charge of the filter because it provides twice the charge as Na(+) while occupying the same space. The CSC mechanism further implies that the main determinant of Ca(2+) versus Na(+) selectivity is the density of charged particles in the selectivity filter, i.e., the volume of the filter (after fixing the number of charged groups in the filter). In this paper we test this hypothesis by changing filter length and/or radius (shape) of the cylindrical selectivity filter of our reduced model. We show that varying volume and shape together has substantially stronger effects than varying shape alone with volume fixed. Our simulations show the importance of depletion zones of ions in determining channel conductance calculated with the integrated Nernst-Planck equation. We show that confining the protein side chains with soft or hard walls does not influence selectivity.

  17. Methyl p-hydroxybenzoate causes pain sensation through activation of TRPA1 channels

    Science.gov (United States)

    Fujita, F; Moriyama, T; Higashi, T; Shima, A; Tominaga, M

    2007-01-01

    Background and purpose: Parabens are commonly added in pharmaceutical, cosmetic and food products because of their wide antibacterial properties, low toxicity, inertness and chemical stability, although the molecular mechanism of their antibacterial effect is not fully understood. Some agonists of the transient receptor potential (TRP) A1 channels are known to have strong antibacterial activities. Therefore, a series of experiments was conducted to find out the effects of parabens on TRP channels expressed in sensory neurons, particularly the TRPA1 channels. Experimental approach: Effects of parabens, especially of methyl p-hydroxybenzoate (methyl paraben) on TRP channel activities were examined using Ca2+-imaging and patch-clamp methods. In addition, an involvement of methyl paraben in the development of pain-related behavior in mice was investigated. Key results: Methyl paraben specifically activated TRPA1 in both HEK293 cells expressing TRPA1 and in mouse sensory neurons with an EC50 value of 4.4 mM, an attainable concentration in methyl paraben-containing products. Methyl paraben caused pain-related behavior in mice similar to that caused by allyl isothiocyanate, which was blocked by the TRP channel blocker, ruthenium red. Conclusions and implications: Our data indicate that methyl paraben is able to activate TRPA1 channels and can cause pain sensation. As such, methyl paraben provides a useful tool for investigating TRPA1 function and development of antinociceptive agents acting on TRPA1 channels. PMID:17351650

  18. ANN Model for Predicting the Impact of Submerged Aquatic Weeds Existence on the Hydraulic Performance of Branched Open Channel System Accompanied by Water Structures

    International Nuclear Information System (INIS)

    Abdeen, Mostafa A. M.; Abdin, Alla E.

    2007-01-01

    The existence of hydraulic structures in a branched open channel system urges the need for considering the gradually varied flow criterion in evaluating the different hydraulic characteristics in this type of open channel system. Computations of hydraulic characteristics such as flow rates and water surface profiles in branched open channel system with hydraulic structures require tremendous numerical effort especially when the flow cannot be assumed uniform. In addition, the existence of submerged aquatic weeds in this branched open channel system adds to the complexity of the evaluation of the different hydraulic characteristics for this system. However, this existence of aquatic weeds can not be neglected since it is very common in Egyptian open channel systems. Artificial Neural Network (ANN) has been widely utilized in the past decade in civil engineering applications for the simulation and prediction of the different physical phenomena and has proven its capabilities in the different fields. The present study aims towards introducing the use of ANN technique to model and predict the impact of submerged aquatic weeds existence on the hydraulic performance of branched open channel system. Specifically the current paper investigates a branched open channel system that consists of main channel supplies water to two branch channels that are infested by submerged aquatic weeds and have water structures such as clear over fall weirs and sluice gates. The results of this study showed that ANN technique was capable, with small computational effort and high accuracy, of predicting the impact of different infestation percentage for submerged aquatic weeds on the hydraulic performance of branched open channel system with two different hydraulic structures

  19. Effect of a Weir-Type Obstruction with Different Geometric and Hydraulic Conditions on Flow Structure in an Open Channel

    Directory of Open Access Journals (Sweden)

    Shahid Ali

    2014-07-01

    Full Text Available This paper presents results from an experimental study which was conducted at Technical University Delft, Netherland. The research was made on obstructions resembling weirs in an open channel. This weir-type obstruction was a representative of groyne/dike in a natural channel. The experimentation was performed in the laboratory for different values of inflow (25 l/sec and 40 l/sec, weir with and without vegetation and with different leeward slopes of the weir (1:4 and 1:7. The results were obtained for Reynolds normal stresses, longitudinal and vertical velocities. A comparison was made between the results of 1:4 and 1:7 leeward slope ratios. The data was collected with a LDA (Laser Doppler Anemometer. The vegetation was modeled with vertical circular rods placed over the crest of the weir. The blockage area due to this vegetation was 25% of the total area. The velocity data was gathered at around ten locations both at upstream and downstream the weir to get an insight into the flow structure. The results have been presented in the shape of vertical profiles both for velocities as well as Reynolds stresses at different locations of the channel.

  20. Structural changes of a light-activated G protein-coupled receptor determined by solid-state NMR: Channeling light energy into the visual pigment rhodopsin

    Science.gov (United States)

    Crocker, Evan Daniel

    Absorption of light by the visual pigment rhodopsin triggers an 11- cis to all-trans isomerization of the retinal chromophore within the interior of this G protein-coupled receptor. Two-dimensional solid-state NMR of rhodopsin and the active metarhodopsin II intermediate is used to determine the trajectory of the retinal and the effects of retinal isomerization on the structure of the protein. Structural constraints obtained in this study indicate that helices H5, H6 and H7 undergo changes in orientation relative to the H1--H4 core of the receptor upon retinal isomerization. The position of the retinal beta-ionone ring in metarhodopsin II was found to translate toward and interact with H5. Changes observed in the H4--H5 interface are consistent with a small counter clockwise rotation of H5, as observed from the extracellular side of the protein. Retinal isomerization also alters the structure and position of H6. The position of Trp265 relative to H3 and the retinal in metarhodopsin II indicates that the extracellular end of H6 moves inward and rotates upon activation. Together with previous EPR measurements of the relative positions of the intracellular ends of H3 and H6 in metarhodopsin II, the NMR constraints define how Trp265 serves as a lever for the motion of H6. Retinal translation also leads to an inward motion of the extracellular end of H7, suggesting that H6 and H7 move in concert upon receptor activation. A function of the highly conserved NPxxY sequence on the intracellular end of H7 is proposed. Based on the observations described above and indications that helices H1 through H4 form a stable core that serves as a platform for the motion of H5, H6 and H7, a model for the structure of the active state of rhodopsin is presented. Aspects of this model are put into the context of the proposed activation mechanisms of other members of the GPCR superfamily.

  1. Uterine deletion of Trp53 compromises antioxidant responses in mouse decidua

    Energy Technology Data Exchange (ETDEWEB)

    Burnum, Kristin E.; Hirota, Yasushi; Baker, Erin Shammel; Yoshie, Mikihiro; Ibrahim, Yehia M.; Monroe, Matthew E.; Anderson, Gordon A.; Smith, Richard D.; Daikoku, Takiko; Dey, Sudhansu K.

    2012-09-01

    Preterm birth is a global health issue impacting both mothers and children. However, the etiology of preterm birth is not clearly understood. From our recent finding that premature decidual senescence with terminal differentiation is a cause of preterm birth in mice with uterine Trp53 deletion, encoding p53 protein, led us to explore other potential factors that are related to preterm birth. Utilizing proteomics approaches, here we show that 183 candidate proteins cause significant changes in decidua with Trp53 deletion as compared to normal decidua. Functional categorization of these proteins unveiled new pathways that are influenced by p53. In particular, downregulation of a cluster of antioxidant proteins in p53 deficient decidua suggests that increased oxidative stress could be one cause of preterm birth in mice with uterine deletion of Trp53.

  2. A proton wire and water channel revealed in the crystal structure of isatin hydrolase

    DEFF Research Database (Denmark)

    Bjerregaard-Andersen, Kaare; Sommer, Theis; Jensen, Jan Kristian

    2014-01-01

    to a novel family of metalloenzymes that include the bacterial kynurenine formamidase. The product state, mimicked by bound thioisatinate, reveals a water molecule that bridges the thioisatinate to a proton wire in an adjacent water channel and thus allows the proton released by the reaction to escape only...... when the product is formed. The functional proton wire present in IH-b represents a unique catalytic feature common to all hydrolases is here trapped and visualized for the first time. The local molecular environment required to coordinate thioisatinate allows stronger and more confident identification...

  3. Endoglin Selectively Modulates Transient Receptor Potential Channel Expression in Left and Right Heart Failure

    Science.gov (United States)

    Morine, Kevin J.; Paruchuri, Vikram; Qiao, Xiaoying; Aronovitz, Mark; Pham, Duc Thinh; Huggins, Gordon S.; DeNofrio, David; Kiernan, Michael S.; Karas, Richard H.; Kapur, Navin K.

    2017-01-01

    Introduction Transient receptor potential (TRP) channels are broadly expressed cation channels that mediate diverse physiological stimuli and include canonical (TRPC), melastatin (TRPM) and vanilloid (TRPV) subtypes. Recent studies have implicated a role for TRPC6 channels as an important component of signaling via the cytokine, transforming growth factor beta 1 (TGFb1) in right (RV) or left ventricular (LV) failure. Endoglin is a transmembrane glycoprotein that promotes TRPC6 expression and TGFb1 activity. No studies have defined biventricular expression of all TRP channel family members in heart failure. Hypothesis We hypothesized that heart failure is associated with distinct patterns of TRP channel expression in the LV and RV. Methods Paired viable left (LV) and right (RV) ventricular free wall tissue was obtained from human subjects with end-stage heart failure (n=12) referred for cardiac transplantation or biventricular assist device implantation. Paired LV and RV samples from human subjects without heart failure served as controls (n=3). To explore a functional role for endoglin (Eng) as a regulator of TRP expression in response to RV or LV pressure overload, wild-type (Eng+/+) and Eng haploinsufficient (Eng+/−) mice were exposed to thoracic aortic (TAC) or pulmonary arterial (PAC) constriction for 8 weeks. Biventricular tissue was analyzed by real-time polymerase chain reaction. Results Compared to non-failing human LV and RV samples, mRNA levels of TRPC1, 3, 4, 6 and TRPV-2 were increased and TRPM2, 3, and 8 were decreased in failing LV and RV samples. TRPC1 and 6 levels were higher in failing RV compared to failing LV samples. After TAC, murine LV levels of TPRC1 and 6 were increased in both Eng +/+ and Eng +/− mice compared to sham controls. LV levels of TRPC4; TRPM3 and 7; TRPV2 and 4 were increased in Eng +/+, not Eng +/− mice after TAC. After PAC, all TRP channel family members were increased in the RV, but not LV, of Eng +/+ compared to sham

  4. Channelling and channelling radiation

    International Nuclear Information System (INIS)

    Soerensen, A.H.; Uggerhoej, E.

    1987-01-01

    The study of channelling phenomena has developed rapidly since the early 1960s and today channelling has found many applications. The radiation emitted by channelled megaelectronvolt and gigaelectronvolt electrons and positrons has been investigated extensively and the possibility of, for example, constructing intense tunable X- and γ-ray sources is being explored. Multi-gigaelectronvolt radiation and pair-creation processes in single crystals show similarities with strong-field effects and are of particular interest because of high production rates that persist far beyond the channelling regime. (author)

  5. Review article: transient receptor potential channels as possible therapeutic targets in irritable bowel syndrome.

    Science.gov (United States)

    Beckers, A B; Weerts, Z Z R M; Helyes, Z; Masclee, A A M; Keszthelyi, D

    2017-11-01

    Abdominal pain in irritable bowel syndrome (IBS) remains challenging to treat effectively. Researchers have attempted to elucidate visceral nociceptive processes in order to guide treatment development. Transient receptor potential (TRP) channels have been implied in the generation (TRPV1, TRPV4, TRPA1) and inhibition (TRPM8) of visceral pain signals. Pathological changes in their functioning have been demonstrated in inflammatory conditions, and appear to be present in IBS as well. To provide a comprehensive review of the current literature on TRP channels involved in visceral nociception. In particular, we emphasise the clinical implications of these nociceptors in the treatment of IBS. Evidence to support this review was obtained from an electronic database search via PubMed using the search terms "visceral nociception," "visceral hypersensitivity," "irritable bowel syndrome" and "transient receptor potential channels." After screening the abstracts the articles deemed relevant were cross-referenced for additional manuscripts. Recent studies have resulted in significant advances in our understanding of TRP channel mediated visceral nociception. The diversity of TRP channel sensitization pathways is increasingly recognised. Endogenous TRP agonists, including poly-unsaturated fatty acid metabolites and hydrogen sulphide, have been implied in augmented visceral pain generation in IBS. New potential targets for treatment development have been identified (TRPA1 and TRPV4,) and alternative means of affecting TRP channel signalling (partial antagonists, downstream targeting and RNA-based therapy) are currently being explored. The improved understanding of mechanisms involved in visceral nociception provides a solid basis for the development of new treatment strategies for abdominal pain in IBS. © 2017 John Wiley & Sons Ltd.

  6. Structural Waters Define a Functional Channel Mediating Activation of the GPCR, rhodopsin

    Energy Technology Data Exchange (ETDEWEB)

    Angel, T.; Gupta, S; Jastrzebska, B; Palczewski, K; Chance, M

    2009-01-01

    Structural water molecules may act as prosthetic groups indispensable for proper protein function. In the case of allosteric activation of G protein-coupled receptors (GPCRs), water likely imparts structural plasticity required for agonist-induced signal transmission. Inspection of structures of GPCR superfamily members reveals the presence of conserved embedded water molecules likely important to GPCR function. Coupling radiolytic hydroxyl radical labeling with rapid H2O18 solvent mixing, we observed no exchange of these structural waters with bulk solvent in either ground state or for the Meta II or opsin states. However, the radiolysis approach permitted labeling of selected side chain residues within the transmembrane helices and revealed activation-induced changes in local structural constraints likely mediated by dynamics of both water and protein. These results suggest both a possible general mechanism for water-dependent communication in family A GPCRs based on structural conservation, and a strategy for probing membrane protein structure.

  7. TrpA1 activation in peripheral sensory neurons underlies the ionic basis of pain hypersensitivity in response to vinca alkaloids.

    Directory of Open Access Journals (Sweden)

    Nina Boiko

    Full Text Available Chemotherapy induced peripheral neuropathy (CIPN, a side effect of many anti-cancer drugs including the vinca alkaloids, is characterized by a severe pain syndrome that compromises treatment in many patients. Currently there are no effective treatments for this pain syndrome except for the reduction of anti-cancer drug dose. Existing data supports the model that the pain associated with CIPN is the result of anti-cancer drugs augmenting the function of the peripheral sensory nociceptors but the cellular mechanisms underlying the effects of anti-cancer drugs on sensory neuron function are not well described. Studies from animal models have suggested a number of disease etiologies including mitotoxicity, axonal degeneration, immune signaling, and reduced sensory innervations but these outcomes are the result of prolonged treatment paradigms and do not necessarily represent the early formative events associated with CIPN. Here we show that acute exposure to vinca alkaloids results in an immediate pain syndrome in both flies and mice. Furthermore, we demonstrate that exposure of isolated sensory neurons to vinca alkaloids results in the generation of an inward sodium current capable of depolarizing these neurons to threshold resulting in neuronal firing. These neuronal effects of vinca alkaloids require the transient receptor potential ankyrin-1 (TrpA1 channel, and the hypersensitization to painful stimuli in response to the acute exposure to vinca alkaloids is reduced in TrpA1 mutant flies and mice. These findings demonstrate the direct excitation of sensory neurons by CIPN-causing chemotherapy drugs, and identify TrpA1 as an important target during the pathogenesis of CIPN.

  8. Novel structure design of composite proton exchange membranes with continuous and through-membrane proton-conducting channels

    Science.gov (United States)

    Wang, Hang; Tang, Chenxiao; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Li, Hongjun

    2017-10-01

    The primary goal of this study is to develop a high-performanced proton exchange membrane with the characteristics of through-membrane and continuous solution blown nanofibers as proton-conducting channels. The curled sulfonated phenolphthalein poly (ether sulfone) and poly (vinylidene fluoride) nanofibers were separately fabricated through the solution blowing process which is a new nanofiber fabricating method with high productivity, then they were fabricated into a sandwich-structured mat. Then this sandwich-structured mat was hot-pressed to form the designed structure using different melting temperatures of the two polymers by melting and making poly (vinylidene fluoride) flow into the phenolphthalein poly (ether sulfone) nanofiber mat. The characteristics of the composite membrane, such as morphology and performance of the membrane, were investigated. The characterization results proved the successful preparation of the membrane structure. Performance results showed that the novel structured membrane with through-membrane nanofibers significantly improved water swelling and methanol permeability, though its conductivity is lower than that of Nafion, the cell performance showed comparable results. Therefore, the novel structure design can be considered as a promising method for preparing of proton exchange membranes.

  9. Modular Organization of the NusA- and NusG-Stimulated RNA Polymerase Pause Signal That Participates in the Bacillus subtilis trp Operon Attenuation Mechanism.

    Science.gov (United States)

    Mondal, Smarajit; Yakhnin, Alexander V; Babitzke, Paul

    2017-07-15

    The Bacillus subtilis trpEDCFBA operon is regulated by a transcription attenuation mechanism in which tryptophan-activated TRAP binds to the nascent transcript and blocks the formation of an antiterminator structure such that the formation of an overlapping intrinsic terminator causes termination in the 5' untranslated region (5' UTR). In the absence of bound TRAP, the antiterminator forms and transcription continues into the trp genes. RNA polymerase pauses at positions U107 and U144 in the 5' UTR. The general transcription elongation factors NusA and NusG stimulate pausing at both positions. NusG-stimulated pausing at U144 requires sequence-specific contacts with a T tract in the nontemplate DNA (ntDNA) strand within the paused transcription bubble. Pausing at U144 participates in a trpE translation repression mechanism. Since U107 just precedes the critical overlap between the antiterminator and terminator structures, pausing at this position is thought to participate in attenuation. Here we carried out in vitro pausing and termination experiments to identify components of the U107 pause signal and to determine whether pausing affects the termination efficiency in the 5' UTR. We determined that the U107 and U144 pause signals are organized in a modular fashion containing distinct RNA hairpin, U-tract, and T-tract components. NusA-stimulated pausing was affected by hairpin strength and the U-tract sequence, whereas NusG-stimulated pausing was affected by hairpin strength and the T-tract sequence. We also determined that pausing at U107 results in increased TRAP-dependent termination in the 5' UTR, implying that NusA- and NusG-stimulated pausing participates in the trp operon attenuation mechanism by providing additional time for TRAP binding. IMPORTANCE The expression of several bacterial operons is controlled by regulated termination in the 5' untranslated region (5' UTR). Transcription attenuation is defined as situations in which the binding of a regulatory

  10. Generalized non-Local Resistance Expression and its Application in F/N/F Spintronic Structure with Graphene Channel

    Science.gov (United States)

    Wei, Huazhou; Fu, Shiwei

    We report our work on the spin transport properties in the F/N/F(ferromagnets/normal metal/ferromagnets) spintronic structure from a new theoretical perspective. A significant problem in the field is to explain the inferior measured order of magnitude for spin lifetime. Based on the known non-local resistance formula and the mechanism analysis of spin-flipping within the interfaces between F and N, we analytically derive a broadly applicable new non-local resistance expression and a generalized Hanle curve formula. After employing them in the F/N/F structure under different limits, especially in the case of graphene channel, we find that the fitting from experimental data would yield a longer spin lifetime, which approaches its theoretical predicted value in graphene. The authors acknowledge the financial support by China University of Petroleum-Beijing and the Key Laboratory of Optical Detection Technology for Oil and Gas in this institution.

  11. Fluid-structure-interaction of a flag in a channel flow

    Science.gov (United States)

    Liu, Yingzheng; Yu, Yuelong; Zhou, Wenwu; Wang, Weizhe

    2017-11-01

    The unsteady flow field and flapping dynamics of an inverted flag in water channel are investigated using time resolved particle image velocimetry (TR-PIV) measurements. The dynamically deformed profiles of the inverted flag are determined by a novel algorithm that combines morphological image processing and principle component analysis. Instantaneous flow field, phase averaged vorticity, time-mean flow field and turbulent kinematic energy are addressed for the flow. Four modes are discovered as the dimensionless bending stiffness decreases, i.e., the straight mode, the biased mode, the flapping mode and the deflected mode. Among all modes, the flapping mode is characterized by large flapping amplitude and the reverse von Kármán vortex street wake, which is potential to enhance heat transfer remarkably. National Natural Science Foundation of China.

  12. Interaction between the Gly460Trp alpha-adducin gene variant and diuretics on the risk of myocardial infarction

    NARCIS (Netherlands)

    van Wieren-de Wijer, Diane B M A; Maitland-van der Zee, Anke-Hilse; de Boer, Anthonius; Kroon, Abraham A; de Leeuw, Peter W; Schiffers, Paul; Janssen, Rob G J H; Psaty, Bruce M; van Duijn, Cornelia M; Stricker, Bruno H Ch; Klungel, Olaf H

    INTRODUCTION: The Gly460Trp variant of the alpha-adducin gene has been associated with the salt-sensitive and diuretic responsive form of hypertension. OBJECTIVE: The aim of the study was to determine whether the alpha-adducin 460Trp variant allele modifies the risk-lowering effect of diuretics on

  13. The feasible study of the water flow in the micro channel with the Y-junction and narrow structure for various flow rates

    Science.gov (United States)

    Jasikova, D.; Kotek, M.; Kopecky, V.

    2015-05-01

    Here we present the results of measurement in micro-channel with the Y-junction and narrow structure for various flow rates. There was used BSG micro-channel with trapezoidal cross-section. The parameters of the channel are described in the paper. The flow in the micro-channel was invested with micro-PIV technique and various flow rates were set on each inlet. The resulting flow rate in the steady area follows the laminar flow with very low Re 30. Here we are focused on the flow characteristic in the Y-junction and in selected narrow structure. The fluid flow is evaluated with vector and scalar maps and the profile plots that were taken in the point of interest.

  14. The feasible study of the water flow in the micro channel with the Y-junction and narrow structure for various flow rates

    Directory of Open Access Journals (Sweden)

    Jasikova D.

    2015-01-01

    Full Text Available Here we present the results of measurement in micro-channel with the Y-junction and narrow structure for various flow rates. There was used BSG micro-channel with trapezoidal cross-section. The parameters of the channel are described in the paper. The flow in the micro-channel was invested with micro-PIV technique and various flow rates were set on each inlet. The resulting flow rate in the steady area follows the laminar flow with very low Re 30. Here we are focused on the flow characteristic in the Y-junction and in selected narrow structure. The fluid flow is evaluated with vector and scalar maps and the profile plots that were taken in the point of interest.

  15. Alpha-adducin Gly460Trp polymorphism and renal hemodynamics in essential hypertension

    NARCIS (Netherlands)

    Beeks, Esther; van der Klauw, Melanie M; Kroon, Abraham A; Spiering, Wilko; Fuss-Lejeune, Monique J M J; de Leeuw, Peter W

    2004-01-01

    Previous studies have shown an association between the alpha-adducin Gly460Trp polymorphism and salt-sensitive hypertension. Not much is known about the effects of the variants of this polymorphism on renal hemodynamics and function. Therefore, we performed the present study to investigate the

  16. Urea and Guanidinium Induced Denaturation of a Trp-Cage Miniprotein

    Czech Academy of Sciences Publication Activity Database

    Heyda, Jan; Kožíšek, Milan; Bednárová, Lucie; Thompson, G.; Konvalinka, Jan; Vondrášek, Jiří; Jungwirth, Pavel

    2011-01-01

    Roč. 115, č. 28 (2011), s. 8910-8924 ISSN 1520-6106 R&D Projects: GA MŠk LC512; GA ČR GA203/08/0114 Institutional research plan: CEZ:AV0Z40550506 Keywords : trp-cage denaturation * urea * guanidinium * molecular dynamics Subject RIV: CC - Organic Chemistry Impact factor: 3.696, year: 2011

  17. Alpha-lactalbumin combined with a regular diet increases plasma Trp-LNAA ratio

    NARCIS (Netherlands)

    Beulens, J.W.J.; Bindels, J.G.; Graaf, de C.

    2004-01-01

    Brain serotonin influences food intake and mood. It is synthesised from tryptophan (Tip) of which uptake in the brain is dependent on plasma ratio of tryptophan to the sum of other large neutral amino acids (Trp-LNAA). A carbohydrate-rich diet increases this ratio, whereas a protein-rich diet

  18. Prostaglandin H synthase-mediated bioactivation of the amino acid pyrolysate product Trp P-2

    Energy Technology Data Exchange (ETDEWEB)

    Petry, T.W.; Krauss, R.S.; Eling, T.E.

    1986-08-01

    We report evidence that the mutagen and carcinogen 3-amino-1-methyl-5H pyrido(4,3b)indole (Trp P-2) is a substrate for co-oxidation by prostaglandin H synthase (PHS) in ram seminal vesicle (RSV) microsomes. Trp P-2 serves as a reducing cofactor for the hydroperoxidase activity of PHS as shown by the concentration-dependent inhibition of the hydroperoxidase catalyzed incorporation of molecular oxygen into phenylbutazone. Spectral data suggest that this metabolism results in disruption of the double bond conjugation within the nucleus of the molecule. A single metabolite peak which was dependent upon arachidonic acid and substrate concentration was separated from the parent compound by h.p.l.c. following incubation with RSV microsomes. Co-oxidation of Trp P-2 produced reactive intermediates which bound covalently to microsomal protein (9 nmol/mg) and to calf thymus DNA (475 pmol/mg). Binding was inhibited by indomethacin, and supported by substitution of hydrogen peroxide for arachidonic acid. These data suggest a possible role for PHS in the in situ activation of Trp P-2 to its ultimate carcinogenic form in tissues which contain PHS.

  19. A survey on the biochemical parameters in serum of the Azarbaijan buffaloes with TRP

    Directory of Open Access Journals (Sweden)

    Gh. Mousavi

    2010-02-01

    Full Text Available TRP disease is one of the prevalent disease in cows and buffaloes that most common in dairy cows feed by prepared foods but cases occur infrequently in buffaloes, beef cattle, sheep and goats. In this research 15 Azerbaijan buffaloes with TRP were studied. Firstly affected buffaloes were diagnosed based on clinical signs. The blood samples were obtained from the related animals and after separation blood serum by centrifuging, the biochemical tests, such as sodium, potassium, Glucose, phosphorus, albumin and calcium levels in serum were measured. The mean levels of sodium, potassium, Glucose, phosphorus, albumin and calcium in buffaloes with TRP were 112 mEq/Lit, 3.11 mEq/Lit, 42.29 mg/dl, 3.84 mg/dl, 544 mg/dl, 8.60 mg/dl. In this study the mean levels of sodium, potassium, phosphorus in buffaloes with TRP was less than the normal buffaloes and the mean levels of calcium, Glucose as such as the normal animals and the mean levels of albumin was higher than the normal buffaloes.

  20. Rate constant and reaction coordinate of Trp-cage folding in explicit water

    NARCIS (Netherlands)

    Juraszek, J.; Bolhuis, P.G.

    2008-01-01

    We report rate constant calculations and a reaction coordinate analysis of the rate-limiting folding and unfolding process of the Trp-cage mini-protein in explicit solvent using transition interface sampling. Previous transition path sampling simulations revealed that in this (un)folding process the

  1. A low-voltage flash memory cell utilizing the gate-injection program/erase method with a recessed channel structure

    International Nuclear Information System (INIS)

    Wu Dake; Huang Ru; Wang Pengfei; Tang Poren; Wang Yangyuan

    2008-01-01

    In this paper, a low-voltage recessed channel SONOS flash memory using the gate-injection program/erase method is proposed and investigated for NAND application. It is shown that the proposed flash memory can achieve 8 V lower programming voltage compared with planar flash memory, due to the effective capacitance coupling and the electric-field enhancement by combining the recessed channel structure and the gate-injection program/erase method. In addition, more than 30% larger threshold voltage window and improved short channel effects can be obtained in the proposed flash memory

  2. Using Structure-from-Motion to Quantify Sediment Accumulation and Bedrock Erosion in a Debris-Flow Dominated Channel

    Science.gov (United States)

    Reitman, N. G.; Rengers, F.; Kean, J. W.

    2016-12-01

    One of the highest frequencies of observed debris flows in the US is located at the Chalk Cliffs in central Colorado. This high rate of debris-flow activity ( 3 per year) is supported by a similarly high rate of sediment supply from rock fall and ravel due to frost weathering of the highly-erodible, hydrothermally-altered quartz monzonite cliffs during the winter months. A first step toward understanding debris-flow initiation, and channel and hillslope evolution, is to quantify the magnitude and spatial distribution of sediment that accumulates by the end of the winter period. Here we test the ability of structure-from-motion photogrammetric surveys to produce high-resolution point clouds in order to quantify sediment deposition, and possibly bedrock erosion. We use point clouds obtained from surveys conducted in late September 2015 and early June 2016 to measure sediment deposition in a 42-m-long channel over one winter. All surveys are co-registered with control points (screws drilled into bedrock) measured in a local coordinate system with a total station. Point clouds derived from these surveys have average point densities >200,000 pts/m2, and accuracies within 2 cm. Initial analysis shows accumulation of 10-50 cm ( 10 m3) of unconsolidated loose sediment over eight months, providing ample material for debris-flow initiation during the following summer season. Sediment accumulated in a spatially-variable pattern dependent on existing channel-bottom bedrock topography. Future surveys are planned in order to measure bedrock erosion by debris flows and variation in sediment deposition rate through time. Our analysis indicates that photogrammetric surveys provide a high level of detail at low cost, and thus are a useful geomorphic monitoring tool that will ultimately lead to better understanding of the processes that contribute to debris-flow activity and landscape evolution.

  3. Design, synthesis and pharmacological characterization of analogs of 2-aminoethyl diphenylborinate (2-APB), a known store-operated calcium channel blocker, for inhibition of TRPV6-mediated calcium transport.

    Science.gov (United States)

    Hofer, Alexandre; Kovacs, Gergely; Zappatini, Anna; Leuenberger, Michele; Hediger, Matthias A; Lochner, Martin

    2013-06-01

    2-Aminoethyl diphenylborinate (2-APB) is a known modulator of the IP3 receptor, the calcium ATPase SERCA, the calcium release-activated calcium channel Orai and TRP channels. More recently, it was shown that 2-APB is an efficient inhibitor of the epithelial calcium channel TRPV6 which is overexpressed in prostate cancer. We have conducted a structure-activity relationship study of 2-APB congeners to understand their inhibitory mode of action on TRPV6. Whereas modifying the aminoethyl moiety did not significantly change TRPV6 inhibition, substitution of the phenyl rings of 2-APB did. Our data show that the diaryl borinate moiety is required for biological activity and that the substitution pattern of the aryl rings can influence TRPV6 versus SOCE inhibition. We have also discovered that 2-APB is hydrolyzed and transesterified within minutes in solution. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. The structural elements and tectonics of the Lake Van basin (Eastern Anatolia) from multi-channel seismic reflection profiles

    Science.gov (United States)

    Toker, Mustafa; Sengor, A. M. Celal; Demirel Schluter, Filiz; Demirbag, Emin; Cukur, Deniz; Imren, Caner; Niessen, Frank; PaleoVan-Working Group

    2017-05-01

    This study analyzed multi-channel seismic reflection data from Lake Van, Eastern Anatolia, to provide key information on the structural elements, deformational patterns and overall tectonic structure of the Lake Van basin. The seismic data reveal three subbasins (the Tatvan, northern and Ahlat subbasins) separated by structural ridges (the northern and Ahlat ridges). The Tatvan basin is a tilted wedge-block in the west, it is a relatively undeformed and flat-lying deep basin, forming a typical example of strike-slip sedimentation. Seismic sections reveal that the deeper sedimentary sections of the Tatvan basin are locally folded, gently in the south and more intensely further north, suggesting a probable gravitational "wedge-block" instability, oblique to the northern margin. The northern subbasin, bounded by normal oblique faults, forms a basin-margin graben structure that is elongated in a northeast-southwest direction. The east-west trending Ahlat ridge forms a fault-wedged sedimentary ridge and appears to offset by reverse oblique faults forming as a push-up rhomb horst structure. The Ahlat subbasin is a fault-wedged trough fill that is elongated in the west-east direction and appears as a horst-foot graben formed by the normal oblique faults. The northeast-southwest directed northern ridge is a faulted crestal terrace of a sublacustrine basement block. Its step-like morphology, in response to the downfaulting of the Tatvan basin, as well as its backthrusted appearance, indicates the normal oblique nature of the bounding faults. The lacustrine shelf and slope show distinctive stratigraphic features; progradational deltas, submerged fluvial channels, distorted and collapsed beddings and soft sediment deformation structures, characterizing a highly unstable nature of shelf caused by strong oblique faulting and related earthquakes. The faulting caused uplift of the Çarpanak spur zone, together with the northeastern Erek delta, deformation of deltaic structures

  5. Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks

    Science.gov (United States)

    Kanno, Yoichiro; Vokoun, Jason C.; Letcher, Benjamin H.

    2011-01-01

    Linear and heterogeneous habitat makes headwater stream networks an ideal ecosystem in which to test the influence of environmental factors on spatial genetic patterns of obligatory aquatic species. We investigated fine-scale population structure and influence of stream habitat on individual-level genetic differentiation in brook trout (Salvelinus fontinalis) by genotyping eight microsatellite loci in 740 individuals in two headwater channel networks (7.7 and 4.4 km) in Connecticut, USA. A weak but statistically significant isolation-by-distance pattern was common in both sites. In the field, many tagged individuals were recaptured in the same 50-m reaches within a single field season (summer to fall). One study site was characterized with a hierarchical population structure, where seasonal barriers (natural falls of 1.5–2.5 m in height during summer base-flow condition) greatly reduced gene flow and perceptible spatial patterns emerged because of the presence of tributaries, each with a group of genetically distinguishable individuals. Genetic differentiation increased when pairs of individuals were separated by high stream gradient (steep channel slope) or warm stream temperature in this site, although the evidence of their influence was equivocal. In a second site, evidence for genetic clusters was weak at best, but genetic differentiation between individuals was positively correlated with number of tributary confluences. We concluded that the population-level movement of brook trout was limited in the study headwater stream networks, resulting in the fine-scale population structure (genetic clusters and clines) even at distances of a few kilometres, and gene flow was mitigated by ‘riverscape’ variables, particularly by physical barriers, waterway distance (i.e. isolation-by-distance) and the presence of tributaries.

  6. Novel boron channel-based structure of boron carbide at high pressures

    Science.gov (United States)

    Zhang, Xinxin; Zhao, Yu; Zhang, Miao; Liu, Hanyu; Yao, Yansun; Cheng, Taimin; Chen, Hui

    2017-11-01

    Boron carbide (B4C) is one of the hardest materials known to date. The extreme hardness of B4C arises from architecturally efficient B12 or B11C icosahedrons and strong inter-icosahedral B-C bonding. As an excellent material for use in ballistic armor, the mechanic limit of B4C and possible phase transitions under extreme stress conditions are of great interest. Here we systematically explored the post-icosahedral solid structures of B4C under high pressure, using an unbiased structure search method. A new structure composed of extended framework of B and zigzag chains of C is predicted to be stable above 96 GPa. The new structure was predicted to have a high Vickers hardness of 55 GPa and simultaneously to retain a metallic ground state. The exceptional mechanical properties found in this structure are attributed to strong sp 3 covalent network formed under extreme pressure conditions. The predicted structure represents a new type of superhard boron carbides that form under high pressure without the presence of boron icosahedrons, which encourages experimental exploration in this direction.

  7. NaV1.9 Potentiates Oxidized Phospholipid-Induced TRP Responses Only under Inflammatory Conditions

    Directory of Open Access Journals (Sweden)

    Corinna Martin

    2018-01-01

    Full Text Available Oxidized phospholipids (OxPL like oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC were recently identified as novel proalgesic targets in acute and chronic inflammatory pain. These endogenous chemical irritants are generated in inflamed tissue and mediate their pain-inducing function by activating the transient receptor potential channels TRPA1 and TRPV1 expressed in sensory neurons. Notably, prototypical therapeutics interfering with OxPL were shown to inhibit TRP channel activation and pain behavior. Here, we asked how OxPL excite primary sensory neurons of dorsal root ganglia (DRG neurons from mice of either sex. Acute stimulation of sensory neurons with the prototypical OxPL 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphocholine (PGPC evoked repetitive calcium spikes in small-diameter neurons. As NaV1.9, a voltage-gated sodium channel involved in nociceptor excitability, was previously shown to be essential for the generation of calcium spikes in motoneurons, we asked if this channel is also important for OxPL mediated calcium spike and action potential generation in nociceptors. In wild-type and NaV1.9-deficient neurons, the action potential firing rate and the calcium spike frequency to an acute PGPC stimulus was similar. When preincubated with inflammatory mediators, both, the action potential firing rate and the calcium spike frequency were markedly increased in response to an acute PGPC stimulus. However, this potentiating effect was completely lost in NaV1.9-deficient small-diameter neurons. After treatment with inflammatory mediators, the resting membrane potential of NaV1.9 KO neurons was slightly more negative than that of wild-type control neurons. This suggests that NaV1.9 channels are active under this condition and therefore increases the ease with which action potentials are elicited after OxPL stimulation. In summary, our data suggest that NaV1.9 has a switch function to potentiate the receptor potentials

  8. Acupuncture Alleviates Colorectal Hypersensitivity and Correlates with the Regulatory Mechanism of TrpV1 and p-ERK

    Directory of Open Access Journals (Sweden)

    Shao-Jun Wang

    2012-01-01

    Full Text Available Here we used a mouse model of zymosan-induced colorectal hypersensitivity, a similar model of IBS in our previous work, to evaluate the effectiveness of the different number of times of acupuncture and elucidate its potential mechanism of EA treatment. Colorectal distension (CRD tests show that intracolonic zymosan injection does, while saline injection does not, induce a typical colorectal hypersensitivity. EA treatment at classical acupoints Zusanli (ST36 and Shangjuxu (ST37 in both hind limbs for 15 min slightly attenuated and significantly blunted the hypersensitive responses after first and fifth acupunctures, respectively, to colorectal distention in zymosan treatment mice, but not in saline treatment mice. Western blot results indicated that ion channel and TrpV1 expression in colorectum as well as ERK1/2 MAPK pathway activation in peripheral and central nerve system might be involved in this process. Hence, we conclude that EA is a potential therapeutic tool in the treatment and alleviation of chronic abdominal pain, and the effectiveness of acupuncture analgesia is accumulative with increased number of times of acupuncture when compared to that of a single time of acupuncture.

  9. Acupuncture Alleviates Colorectal Hypersensitivity and Correlates with the Regulatory Mechanism of TrpV1 and p-ERK

    Science.gov (United States)

    Wang, Shao-Jun; Yang, Hao-Yan; Xu, Guo-Shuang

    2012-01-01

    Here we used a mouse model of zymosan-induced colorectal hypersensitivity, a similar model of IBS in our previous work, to evaluate the effectiveness of the different number of times of acupuncture and elucidate its potential mechanism of EA treatment. Colorectal distension (CRD) tests show that intracolonic zymosan injection does, while saline injection does not, induce a typical colorectal hypersensitivity. EA treatment at classical acupoints Zusanli (ST36) and Shangjuxu (ST37) in both hind limbs for 15 min slightly attenuated and significantly blunted the hypersensitive responses after first and fifth acupunctures, respectively, to colorectal distention in zymosan treatment mice, but not in saline treatment mice. Western blot results indicated that ion channel and TrpV1 expression in colorectum as well as ERK1/2 MAPK pathway activation in peripheral and central nerve system might be involved in this process. Hence, we conclude that EA is a potential therapeutic tool in the treatment and alleviation of chronic abdominal pain, and the effectiveness of acupuncture analgesia is accumulative with increased number of times of acupuncture when compared to that of a single time of acupuncture. PMID:23097675

  10. Crystal structure of dimeric cardiac L-type calcium channel regulatory domains bridged by Ca[superscript 2+]·calmodulins

    Energy Technology Data Exchange (ETDEWEB)

    Fallon, Jennifer L.; Baker, Mariah R.; Xiong, Liangwen; Loy, Ryan E.; Yang, Guojun; Dirksen, Robert T.; Hamilton, Susan L.; Quiocho, Florante A.; (Baylor); (Rochester-Med)

    2009-11-10

    Voltage-dependent calcium channels (Ca(V)) open in response to changes in membrane potential, but their activity is modulated by Ca(2+) binding to calmodulin (CaM). Structural studies of this family of channels have focused on CaM bound to the IQ motif; however, the minimal differences between structures cannot adequately describe CaM's role in the regulation of these channels. We report a unique crystal structure of a 77-residue fragment of the Ca(V)1.2 alpha(1) subunit carboxyl terminus, which includes a tandem of the pre-IQ and IQ domains, in complex with Ca(2+).CaM in 2 distinct binding modes. The structure of the Ca(V)1.2 fragment is an unusual dimer of 2 coiled-coiled pre-IQ regions bridged by 2 Ca(2+).CaMs interacting with the pre-IQ regions and a canonical Ca(V)1-IQ-Ca(2+).CaM complex. Native Ca(V)1.2 channels are shown to be a mixture of monomers/dimers and a point mutation in the pre-IQ region predicted to abolish the coiled-coil structure significantly reduces Ca(2+)-dependent inactivation of heterologously expressed Ca(V)1.2 channels.

  11. To Investigate the Flow Structure of Discontinuous Vegetation Patches of Two Vertically Different Layers in an Open Channel

    Directory of Open Access Journals (Sweden)

    Naveed Anjum

    2018-01-01

    Full Text Available In the present study, the flow structure of discontinuous double-layered vegetation patches was investigated using a 3D Reynolds stress turbulence model (RSM. The channel domain was built using GAMBIT (Geometry and Mesh Building Intelligent Toolkit. For the simulation and postprocessing, FLUENT (ANSYS was used to analyze the distribution of the mean velocity, Reynolds stresses, and other flow properties against two different flow conditions. The results captured by the turbulence model at specific locations and the cross section are presented in the form of various velocity profiles and contour plots. In the gap portion, the velocity was visibly lower than that in the vegetation areas, while the influence of patch distribution was not visible in the overlying flow layer. The velocity profiles at critical locations were categorized by numerous modulation points and velocity projections close to the bed, principally for positions straight after the vegetation structures. A distinction in the velocity at the topmost of the smaller vegetation structure was prominent. Reynolds stresses, turbulent kinetic energy, and turbulence intensity exhibited large fluctuations inside the vegetation regions and just behind the vegetation structures compared with in the gap regions.

  12. Assessment of the effects of regional channel stability and sediment transport on roadway hydraulic structures : final report.

    Science.gov (United States)

    2014-06-01

    Rivers and streams evolve all the time. As a result, no stream channel is absolutely stable. Channels evolve at various speeds both vertically (degradation/aggradation) and horizontally (meander : migration). They also respond to man-made changes ran...

  13. Fluid escape structures in the Graham Bank region (Sicily Channel, Central Mediterranean) revealing volcanic and neotectonic activity.

    Science.gov (United States)

    Spatola, Daniele; Pennino, Valentina; Basilone, Luca; Interbartolo, Francesco; Micallef, Aaron; Sulli, Attilio; Basilone, Walter

    2016-04-01

    In the Sicily Channel, (Central Mediterranean), two geodynamic processes overlap each other, the Maghrebides-Apennines accretionary prism and the Sicily Channel rift. Moreover, the northwestern sector (Banks sector) is characterised by an irregular seafloor morphology linked to the recent volcanic and tectonic activity.In order to discriminate the role exerted by both the processes in the morphostructural setting of the area we used a dataset of both high and very high resolution single-channel and multi-channel profiles, acquired in the frame of the RITMARE project respectively with CHIRP and sparker, and airgun sources, and high resolution (5 m cell) morpho-bathymetric data. The data allowed us to identify and characterise two areas where different geological features (sedimentary and volcanic) are prevailing. They present fluid escaping evidence, which often appears to be active and generating different types of morphologies (both positive and negative). In the western sector we recognised pockmarks at water depths of 195 to 317 m, with diameters from 25 to 580 m, depths from 1.3 to 15 m, and slope up to 23°. They show sub-circular shape in plan-view and reflectors with upward concavity in cross section, and are oriented along a NW-SE trend.The CHIRP and multichannel profiles highlight fluids that affect the Plio-Quaternary succession, especially in areas where the top surface of the Messinian succession is shallower. Conversely, wipe-out acoustic facies were recognised in proximity of: i) extensional faults of Mesozoic age with NW-SE trend; ii) dip/strike slip faults of Cenozoic age with NW-SE, N-S and about NNE-SSW trends, and iii) extensional neo-tectonic faults with NW-SE and NNW-SSE trends. We cannot exclude that they could feed the shallower reservoir producing a mixing between the two. In the eastern sector we recognised a cluster of volcanoes composed of seven cone-shaped structures (SCV1-7), pertaining to a wide area known as Graham Bank. A detailed

  14. The energy structure and decay channels of the 4p6-shell excited states in Sr

    Science.gov (United States)

    Kupliauskienė, A.; Kerevičius, G.; Borovik, V.; Shafranyosh, I.; Borovik, A.

    2017-11-01

    The ejected-electron spectra arising from the decay of the 4p{}5{{nln}}{\\prime }{l}{\\prime }{n}{\\prime\\prime }{l}{\\prime\\prime } autoionizing states in Sr atoms have been studied precisely at the incident-electron energies close to excitation and ionization thresholds of the 4{{{p}}}6 subshell. The excitation behaviors for 58 lines observed between 12 and 21 eV ejected-electron kinetic energy have been investigated. Also, the ab initio calculations of excitation energies, autoionization probabilities and electron-impact excitation cross sections of the states 4p{}5{{nln}}{\\prime }{l}{\\prime }{n}{\\prime\\prime }{l}{\\prime\\prime } (nl = 4d, 5s, 5p; {n}{\\prime }{l}{\\prime } = 4d, 5s, 5p; {n}{\\prime\\prime }{l}{\\prime\\prime } = 5s, 6s, 7s, 8s, 9s, 5p, 6p, 5d, 6d, 7d, 8d, 4f, 5g) have been performed by employing the large-scale configuration-interaction method in the basis of the solutions of Dirac-Fock-Slater equations. The obtained experimental and theoretical data have been used for the accurate identification of the 60 lines in ejected-electron spectra and the 68 lines observed earlier in photoabsorption spectra. The excitation and decay processes for 105 classified states in the 4p55s{}2{nl}, 4p54d{}2{nl} and 4p55s{{nln}}{\\prime }{l}{\\prime } configurations have been considered in detail. In particular, most of the states lying below the ionization threshold of the 4p6 subshell at 26.92 eV possess up to four decay channels with formation of Sr+ in 5s{}1/2, 4d{}3/{2,5/2} and 5p{}1/{2,3/2} states. Two-step autoionization and two-electron Auger transitions with formation of Sr2+ in the 4p6 {}1{{{S}}}0 ground state are the main decay paths for high-lying autoionizing states. The excitation threshold of the 4{{{p}}}6 subshell in Sr has been established at 20.98 ± 0.05 eV.

  15. Crystal Structure of Inhibitor-Bound P450BM-3 Reveals Open Conformation of Substrate Access Channel

    Energy Technology Data Exchange (ETDEWEB)

    Haines, Donovan C.; Chen, Baozhi; Tomchick, Diana R.; Bondlela, Muralidhar; Hegde, Amita; Machius, Mischa; Peterson, Julian A. (Texas); (UTSMC)

    2008-08-19

    P450BM-3 is an extensively studied P450 cytochrome that is naturally fused to a cytochrome P450 reductase domain. Crystal structures of the heme domain of this enzyme have previously generated many insights into features of P450 structure, substrate binding specificity, and conformational changes that occur on substrate binding. Although many P450s are inhibited by imidazole, this compound does not effectively inhibit P450BM-3. {omega}-Imidazolyl fatty acids have previously been found to be weak inhibitors of the enzyme and show some unusual cooperativity with the substrate lauric acid. We set out to improve the properties of these inhibitors by attaching the {omega}-imidazolyl fatty acid to the nitrogen of an amino acid group, a tactic that we used previously to increase the potency of substrates. The resulting inhibitors were significantly more potent than their parent compounds lacking the amino acid group. A crystal structure of one of the new inhibitors bound to the heme domain of P450BM-3 reveals that the mode of interaction of the amino acid group with the enzyme is different from that previously observed for acyl amino acid substrates. Further, required movements of residues in the active site to accommodate the imidazole group provide an explanation for the low affinity of imidazole itself. Finally, the previously observed cooperativity with lauric acid is explained by a surprisingly open substrate-access channel lined with hydrophobic residues that could potentially accommodate lauric acid in addition to the inhibitor itself.

  16. Fluorescence properties of porcine odorant binding protein Trp 16 residue

    Energy Technology Data Exchange (ETDEWEB)

    Albani, Jihad Rene, E-mail: Jihad-Rene.Albani@univ-lille1.f [Laboratoire de Biophysique Moleculaire, Universite des Sciences et Technologies de Lille, F-59655 Villeneuve d' Ascq Cedex (France)

    2010-11-15

    Summary: The present work deals with fluorescence studies of adult porcine odorant binding protein at pH=7.5. At this pH, the protein is a dimer, each monomer contains one tryptophan residue. Our results show that tryptophan residue displays significant motions and emits with three fluorescence lifetimes. Decay associated spectra showed that the three lifetime's components emanate from sub-structures surrounded by the same microenvironment.

  17. Kinetic structure of large-conductance Ca2+-activated K+ channels suggests that the gating includes transitions through intermediate or secondary states. A mechanism for flickers.

    Science.gov (United States)

    Rothberg, B S; Magleby, K L

    1998-06-01

    Mechanisms for the Ca2+-dependent gating of single large-conductance Ca2+-activated K+ channels from cultured rat skeletal muscle were developed using two-dimensional analysis of single-channel currents recorded with the patch clamp technique. To extract and display the essential kinetic information, the kinetic structure, from the single channel currents, adjacent open and closed intervals were binned as pairs and plotted as two-dimensional dwell-time distributions, and the excesses and deficits of the interval pairs over that expected for independent pairing were plotted as dependency plots. The basic features of the kinetic structure were generally the same among single large-conductance Ca2+-activated K+ channels, but channel-specific differences were readily apparent, suggesting heterogeneities in the gating. Simple gating schemes drawn from the Monod- Wyman-Changeux (MWC) model for allosteric proteins could approximate the basic features of the Ca2+ dependence of the kinetic structure. However, consistent differences between the observed and predicted dependency plots suggested that additional brief lifetime closed states not included in MWC-type models were involved in the gating. Adding these additional brief closed states to the MWC-type models, either beyond the activation pathway (secondary closed states) or within the activation pathway (intermediate closed states), improved the description of the Ca2+ dependence of the kinetic structure. Secondary closed states are consistent with the closing of secondary gates or channel block. Intermediate closed states are consistent with mechanisms in which the channel activates by passing through a series of intermediate conformations between the more stable open and closed states. It is the added secondary or intermediate closed states that give rise to the majority of the brief closings (flickers) in the gating.

  18. Turbulent flow structure at a discordant river confluence: Asymmetric jet dynamics with implications for channel morphology

    Science.gov (United States)

    Sukhodolov, Alexander N.; Krick, Julian; Sukhodolova, Tatiana A.; Cheng, Zhengyang; Rhoads, Bruce L.; Constantinescu, George S.

    2017-06-01

    Only a handful of field studies have examined turbulent flow structure at discordant confluences; the dynamics of flow at such confluences have mainly been examined in the laboratory. This paper reports results of a field-based investigation of turbulent flow structure at a discordant river confluence. These results support the hypothesis that flow at a discordant alluvial confluence with a velocity ratio greater than 2 exhibits jet-like characteristics. Scaling analysis shows that the dynamics of the jet core are quite similar to those of free jets but that the complex structure of flow at the confluence imposes strong effects that can locally suppress or enhance the spreading rate of the jet. This jet-like behavior of the flow has important implications for morphodynamic processes at these types of confluences. The highly energetic core of the jet at this discordant confluence is displaced away from the riverbed, thereby inhibiting scour; however, helical motion develops adjacent to the jet, particularly at high flows, which may promote scour. Numerical experiments demonstrate that the presence or absence of a depositional wedge at the mouth of the tributary can strongly influence detachment of the jet from the bed and the angle of the jet within the confluence.

  19. Hadamard quantum broadcast channels

    Science.gov (United States)

    Wang, Qingle; Das, Siddhartha; Wilde, Mark M.

    2017-10-01

    We consider three different communication tasks for quantum broadcast channels, and we determine the capacity region of a Hadamard broadcast channel for these various tasks. We define a Hadamard broadcast channel to be such that the channel from the sender to one of the receivers is entanglement-breaking and the channel from the sender to the other receiver is complementary to this one. As such, this channel is a quantum generalization of a degraded broadcast channel, which is well known in classical information theory. The first communication task we consider is classical communication to both receivers, the second is quantum communication to the stronger receiver and classical communication to other, and the third is entanglement-assisted classical communication to the stronger receiver and unassisted classical communication to the other. The structure of a Hadamard broadcast channel plays a critical role in our analysis: The channel to the weaker receiver can be simulated by performing a measurement channel on the stronger receiver's system, followed by a preparation channel. As such, we can incorporate the classical output of the measurement channel as an auxiliary variable and solve all three of the above capacities for Hadamard broadcast channels, in this way avoiding known difficulties associated with quantum auxiliary variables.

  20. Fish composition and assemblage structure in three Eastern English Channel macrotidal estuaries: A comparison with other French estuaries

    Science.gov (United States)

    Selleslagh, Jonathan; Amara, Rachid; Laffargue, Pascal; Lesourd, Sandric; Lepage, Mario; Girardin, Michel

    2009-01-01

    This study has analysed for the first time fish composition and assemblage structures of three small macrotidal estuaries of the Eastern English Channel (EEC) and has explored the influences of 19 biotic and abiotic variables on the fish assemblages. Fish from Canche, Authie and Somme estuaries were collected during spring (June 2006 and May 2007) and autumn (September 2006) along the estuarine gradients using a 1.5 m beam trawl. Using identical sampling protocols, the study also analysed and compared for the first time taxonomic and functional aspects of the fish assemblages in 15 estuaries located along the Atlantic and English Channel coasts. SIMPER analysis showed high similarities in fish assemblages in the three EEC estuaries and during either spring or autumn periods. However, intra-estuary similarities were relatively low, indicating that fish assemblage structures (species richnesses or abundances) were more variable within the estuary (salinity gradient) than between estuaries and/or seasons (spring vs autumn). Although numerous environmental variables were included in the study, only 47% of the variability observed in the fish distribution was explained. Fish spatial variations in the EEC estuaries are mostly driven by abiotic variables as opposed to biological interactions. As indicated by CCA, salinity and muddy sediments were the two most important factors structuring the fish assemblages. The macrobenthos being very abundant in the EEC estuaries (580-1121 ind. m -2), the availability of potential prey is probably not a limiting factor in the utilization of estuaries by fish. Contrary to the majority of French estuaries dominated by estuarine species (ES), the fish assemblages of the EEC estuaries are clearly dominated by marine migrant (MM) species (65% on average) with high abundance of juveniles (mostly young-of-the-year). Cluster and SIMPROF's analyses distinguished the functional structure of the 15 estuarine fish assemblages into different

  1. A field investigation of the basaltic ring structures of the Channeled Scabland and the relevance to Mars

    Science.gov (United States)

    Kestay, Laszlo P.; Jaeger, Windy L.

    2015-01-01

    The basaltic ring structure (BRS) is a class of peculiar features only reported in the Channeled Scabland of eastern Washington State. They have been suggested to be good analogs, however, for some circular features on Mars. BRSs are found where Pleistocene floods scoured the Columbia River Basin, stripping off the uppermost part of the Miocene Columbia River Basalt Group and exposing structures that were previously embedded in the lava. The “Odessa Craters,” near Odessa, WA, are 50–500-m-wide BRSs that are comprised of discontinuous, concentric outcrops of subvertically-jointed basalt and autointrusive dikes. Detailed field investigation of the Odessa Craters in planform and a cross-sectional exposure of a similar structure above Banks Lake, WA, lead us to propose that BRSs formed by concurrent phreatovolcanism and lava flow inflation. In this model, phreatovolcanic (a.k.a., “rootless”) cones formed on a relatively thin, active lava flow; the lava flow inflated around the cones, locally inverting topography; tensile stresses caused concentric fracturing of the lava crust; lava from within the molten interior of the flow exploited the fractures and buried the phreatovolcanic cones; and subsequent erosive floods excavated the structures. Another population of BRSs near Tokio Station, WA, consists of single-ringed, raised-rimmed structures that are smaller and more randomly distributed than the Odessa Craters. We find evidence for a phreatovolcanic component to the origin as well, and hypothesize that they are either flood-eroded phreatovolcanic cones or Odessa Crater-like BRSs. This work indicates that BRSs are not good analogs to the features on Mars because the martian features are found on the uneroded surfaces. Despite this, the now superseded concepts for BRS formation are useful for understanding the formation of the martian features.

  2. Structure-function of proteins interacting with the α1 pore-forming subunit of high-voltage-activated calcium channels

    Science.gov (United States)

    Neely, Alan; Hidalgo, Patricia

    2014-01-01

    Openings of high-voltage-activated (HVA) calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, HVA calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1) associated with four additional polypeptide chains β, α2, δ, and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the β-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of HVA calcium channels. PMID:24917826

  3. Structure-function of proteins interacting with the alpha1 pore-forming subunit of high voltage-activated calcium channel

    Directory of Open Access Journals (Sweden)

    Alan eNeely

    2014-06-01

    Full Text Available Openings of high-voltage-activated calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, high-voltage-activated calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1 associated with four additional polypeptide chains β, α2, δ and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the β-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of high-voltage-activated calcium channels.

  4. The calculation technique for accelerating channel of the structure with the space-uniform RFQ focusing

    CERN Document Server

    Tishkin, S S; Kobets, A F; Sanin, V M

    2001-01-01

    Calculations were carried out for the initial part of the heavy ion accelerator with the large mass-to-charge ratio (a/q=46). The process of calculation is divided in four stages.At the first stage the average aperture radius and the field strength are determined according to the initial data. At the second stage the optimization of the accelerating tract is performed. To the purpose, the structure is divided in 6 sections: a funnel (a cone), a bunch former, a prebuncher,an adiabatic buncher, a booster, an accelerating section. At the third stage the obtained data are recalculated in the values of the modulation depth and lengths of the accelerating periods with taking into account the real fields. At the fourth stage the beam parameters at the accelerator output are determined for the tract built with taking into account the space charge forces and the input beam parameters.

  5. Analysis of a grid window structure for RF cavities in a Muon cooling channel

    International Nuclear Information System (INIS)

    Ladran, A.; Li, D.; Moretti, A.; Rimmer, R.; Staples, J.; Virostek, S.; Zisman, M.

    2003-01-01

    We report on the electromagnetic and thermal analysis of a grid window structure for high gradient, low frequency RF cavities. Windows may be utilized to close the beam iris and increase shunt impedance of closed-cell RF cavities. This work complements previous work presented for windows made of solid beryllium foil. An electromagnetic and thermal analysis of the thin wall tubes in a grid pattern was conducted using both MAFIA4 and ANSYS finite element analyses. The results from both codes agreed well for a variety of grid configurations and spacing. The grid configuration where the crossing tubes touched was found to have acceptable E-Fields and H-Fields performance. The thermal profiles for the grid will also be shown to determine a viable cooling profile

  6. IDENTIFYING BANK LENDING CHANNEL IN INDONESIA: A VECTOR ERROR CORRECTION APPROACH WITH STRUCTURAL BREAK

    Directory of Open Access Journals (Sweden)

    Akhsyim Afandi

    2017-03-01

    Full Text Available There was a question whether monetary policy works through bank lending channelrequired a monetary-induced change in bank loans originates from the supply side. Mostempirical studies that employed vector autoregressive (VAR models failed to fulfill thisrequirement. Aiming to offer a solution to this identification problem, this paper developed afive-variable vector error correction (VEC model of two separate bank credit markets inIndonesia. Departing from previous studies, the model of each market took account of onestructural break endogenously determined by implementing a unit root test. A cointegrationtest that took account of one structural break suggested two cointegrating vectors identifiedas bank lending supply and demand relations. The estimated VEC system for both marketssuggested that bank loans adjusted more strongly in the direction of the supply equation.

  7. Ion channel structure. Final technical report, April 1, 1993--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    During the past decade, endogenous antimicrobial peptides have become recognized as important, ubiquitous, and ancient contributors to the innate mechanisms which permit animals (including humans), and plants to resist infection. Most of these host defense peptides are small (18-35 amino acids), amphipathic and possess either an {alpha}-helical or cystine-stabilized {beta}-sheet structure. These peptides are probably too small for enzymatic function and, so far, no specific receptors have been found. All evidence indicates that their target of action is the lipid matrix of the bacterial cytoplasmic membranes. This project aimed at clarifying the mechanism of peptide-membrane interactions, in particular the pore formation by the peptides which appear to be the mode of action of these antimicrobials. Tremendous progress was made during the project period. We summarize our findings in the following report.

  8. Cycling expression and cooperative operator interaction in the trp operon of Escherichia coli.

    Science.gov (United States)

    Hernández-Valdez, Areli; Santillán, Moisés; Zeron, Eduardo S

    2010-04-07

    Oscillatory behaviour in the tryptophan operon of an Escherichia coli mutant strain lacking the enzyme-inhibition regulatory mechanism has been observed by Bliss et al. but not confirmed by others. This behaviour could be important from the standpoint of synthetic biology, whose goals include the engineering of intracellular genetic oscillators. This work is devoted to investigating, from a mathematical modelling point of view, the possibility that the trp operon of the E. coli inhibition-free strain expresses cyclically. For that we extend a previously introduced model for the regulatory pathway of the tryptophan operon in Escherichia coli to account for the observed multiplicity and cooperativity of repressor binding sites. Thereafter we investigate the model dynamics using deterministic numeric solutions, stochastic simulations, and analytic studies. Our results suggest that a quasi-periodic behaviour could be observed in the trp operon expression level of single bacteria. Copyright 2009 Elsevier Ltd. All rights reserved.

  9. Structural, micro-structural and kinematic analyses of channel flow in the Karmostaj salt diapir in the Zagros foreland folded belt, Fars province, Iran

    Science.gov (United States)

    Sarkarinejad, Khalil; Sarshar, Maryam Asadi; Adineh, Sadegh

    2018-02-01

    One of the main characteristic of the Zagros foreland fold-and-thrust belt and the Zagros foreland folded belt are wide distributions of surface extrusion from the Hormuz salt diapirs. This study examines the structure and kinematic of channel flow in the Karmostaj salt diapir in the southwestern part of the Zagros foreland folded belt. This diapir has reached the surface as a result of the channel flow mechanism and has extruded in the southern limb of the Kuh-Gach anticline which is an asymmetric décollement fold with convergence to the south. Structural and microstructural studies and quantitative finite strain (Rs) and kinematic vorticity number (Wk) analyses were carried out within this salt diapir and its namakier. This was in order to investigate the structural evolution in the salt diapiric system, the characteristics and mechanism of the salt flow and the distribution of flow regimes within the salt diapir and interaction of regional tectonics and salt diaprism. The extruded salt has developed a flow foliation sub-parallel to the remnant bedding recorded by different colors, a variety of internal folds including symmetrical and asymmetrical folds and interference fold patterns, shear zones, and boudins. These structures were used to analyze mechanisms and history of diapiric flow and extrusion. The microstructures, reveal various deformation mechanisms in various parts of salt diapir. The measurements of finite strain show that Rs values in the margin of salt diapir are higher than within its namakier which is consistent with the results of structural studies. Mean kinematic vorticity number (Wm) measured in steady state deformation of diapir and namakier is Wm = 0.45-0.48 ± 0.13. The estimated mean finite deformation (Wm) values indicate that 67.8% pure shear and 32.2% simple shear deformation were involved; the implications of which are discussed. The vorticity of flow indicates that in the early stage of growth, Poiseuille flow was the dominate

  10. Apoptosis induced by (di-isopropyloxyphoryl-Trp) 2-Lys-OCH 3 in ...

    Indian Academy of Sciences (India)

    (DIPP-Trp)2-Lys-OCH3 induced a dose-dependent increase of the G2/M cell population in K562 cells, and S cell population in HeLa cells; the sub-G0 population increased dramatically in both cell lines as seen by PI staining experiments using a FACS Calibur Flow cytometer (BeckmanCoulter, USA). Phosphatidylserine ...

  11. Apoptosis induced by (di-isopropyloxyphoryl-Trp) -Lys-OCH in K562 ...

    Indian Academy of Sciences (India)

    PRAKASH KUMAR G

    )2-Lys-OCH3. It inhibited the proliferation of K562 and HeLa cells ..... 33(1), March 2008. Figure 3. Periodic analysis of (DIPP-Trp)2-Lys-OCH3 (A, 40 µM; B, 80 µM) against K562 (A) and HeLa (B) cells with re-feeding of fresh medium in half of ...

  12. Quantum Channels With Memory

    International Nuclear Information System (INIS)

    Rybar, T.

    2012-01-01

    Quantum memory channels represent a very general, yet simple and comprehensible model for causal processes. As such they have attracted considerable research interest, mostly aimed on their transfer capabilities and structure properties. Most notably it was shown that memory channels can be implemented via physically naturally motivated collision models. We also define the concept of repeatable channels and show that only unital channels can be implemented repeat ably with pure memory channels. In the special case of qubit channels we also show that every unital qubit channel has a repeatable implementation. We also briefly explore the possibilities of stroboscopical simulation of channels and show that all random unitary channels can be stroboscopically simulated. Particularly in qubit case, all indivisible qubit channels are also random unitary, hence for qubit all indivisible channels can be stroboscopically simulated. Memory channels also naturally capture the framework of correlated experiments. We develop methods to gather and interpret data obtained in such setting and in detail examine the two qubit case. We also show that for control unitary interactions the measured data will never contradict a simple unitary evolution. Thus no memory effects can be spotted then. (author)

  13. Channeling Polyolefin Molecular Structure - Bulk Property Correlation Strategies for Industrial Applicability

    Science.gov (United States)

    Hule, Rohan; Thurman, Derek; Doufas, Antonios

    Polyolefins occupy a significant volume of the polymer products portfolio in commodity and high value applications. Quantifying and optimizing structure-property relationships enables growth in new markets. It is well recognized that coupling lab-based, comprehensive methodologies with bulk properties of interest to industrial environments offer the greatest potential of technology advancement, ultimately leading to commercial success. It is imperative to recognize the existing gap of knowledge translation between lab measurements and industrial-scale operability. This study highlights experimental HDPEs synthesized from dual, single-site, co-supported catalysts that exhibit enhanced solid-state properties such as stiffness, impact and ESCR surpassing conventional trends. Commercial resins across distinct sub-families were included as well. Commonality amongst these resins is bimodality and broad MW distribution with well-defined splits and spreads. Investigations on commercially relevant parameters such as melt strength, melt elasticity and shear thinning established excellent performance for experimental bimodals, corroborating potential benefits compared to commercial HDPEs. To summarize, the effort highlights well-recognized pathways such as improvements in mechanical and melt properties that can be attributed to apposite tuning of polymer chain architecture and MW distribution with implications across myriad markets. Ultimately, this may serve as a pathway for producing innovative products that deliver business success and growth.

  14. Structure, folding and stability of a minimal homologue from Anemonia sulcata of the sea anemone potassium channel blocker ShK.

    Science.gov (United States)

    Krishnarjuna, Bankala; MacRaild, Christopher A; Sunanda, Punnepalli; Morales, Rodrigo A V; Peigneur, Steve; Macrander, Jason; Yu, Heidi H; Daly, Marymegan; Raghothama, Srinivasarao; Dhawan, Vikas; Chauhan, Satendra; Tytgat, Jan; Pennington, Michael W; Norton, Raymond S

    2018-01-01

    Peptide toxins elaborated by sea anemones target various ion-channel sub-types. Recent transcriptomic studies of sea anemones have identified several novel candidate peptides, some of which have cysteine frameworks identical to those of previously reported sequences. One such peptide is AsK132958, which was identified in a transcriptomic study of Anemonia sulcata and has a cysteine framework similar to that of ShK from Stichodactyla helianthus, but is six amino acid residues shorter. We have determined the solution structure of this novel peptide using NMR spectroscopy. The disulfide connectivities and structural scaffold of AsK132958 are very similar to those of ShK but the structure is more constrained. Toxicity assays were performed using grass shrimp (Palaemonetes sp) and Artemia nauplii, and patch-clamp electrophysiology assays were performed to assess the activity of AsK132958 against a range of voltage-gated potassium (K V ) channels. AsK132958 showed no activity against grass shrimp, Artemia nauplii, or any of the K V channels tested, owing partly to the absence of a functional Lys-Tyr dyad. Three AsK132958 analogues, each containing a Tyr in the vicinity of Lys19, were therefore generated in an effort to restore binding, but none showed activity against any of K V channels tested. However, AsK132958 and its analogues are less susceptible to proteolysis than that of ShK. Our structure suggests that Lys19, which might be expected to occupy the pore of the channel, is not sufficiently accessible for binding, and therefore that AsK132958 must have a distinct functional role that does not involve K V channels. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Relationship between ADD1 Gly460Trp gene polymorphism and essential hypertension in Madeira Island.

    Science.gov (United States)

    Sousa, Ana Célia; Palma Dos Reis, Roberto; Pereira, Andreia; Borges, Sofia; Freitas, Ana Isabel; Guerra, Graça; Góis, Teresa; Rodrigues, Mariana; Henriques, Eva; Freitas, Sónia; Ornelas, Ilídio; Pereira, Décio; Brehm, António; Mendonça, Maria Isabel

    2017-10-01

    Essential hypertension (EH) is a complex disease in which physiological, environmental, and genetic factors are involved in its genesis. The genetic variant of the alpha-adducin gene (ADD1) has been described as a risk factor for EH, but with controversial results.The objective of this study was to evaluate the association of ADD1 (Gly460Trp) gene polymorphism with the EH risk in a population from Madeira Island.A case-control study with 1614 individuals of Caucasian origin was performed, including 817 individuals with EH and 797 controls. Cases and controls were matched for sex and age, by frequency-matching method. All participants collected blood for biochemical and genotypic analysis for the Gly460Trp polymorphism. We further investigated which variables were independently associated to EH, and, consequently, analyzed their interactions.In our study, we found a significant association between the ADD1 gene polymorphism and EH (odds ratio 2.484, P = .01). This association remained statistically significant after the multivariate analysis (odds ratio 2.548, P = .02).The ADD1 Gly460Trp gene polymorphism is significantly and independently associated with EH risk in our population. The knowledge of genetic polymorphisms associated with EH is of paramount importance because it leads to a better understanding of the etiology and pathophysiology of this pathology.

  16. TrpC5 Mediates Acute Leptin and Serotonin Effects via Pomc Neurons

    Directory of Open Access Journals (Sweden)

    Yong Gao

    2017-01-01

    Full Text Available The molecular mechanisms underlying acute leptin and serotonin 2C receptor-induced hypophagia remain unclear. Here, we show that neuronal and pro-opiomelanocortin (Pomc-specific loss of transient receptor potential cation 5 (TrpC5 subunits is sufficient to decrease energy expenditure and increase food intake resulting in elevated body weight. Deficiency of Trpc5 subunits in Pomc neurons is also sufficient to block the anorexigenic effects of leptin and serotonin 2C receptor (Ht2Cr agonists. The loss of acute anorexigenic effects of these receptors is concomitant with a blunted electrophysiological response to both leptin and Ht2Cr agonists in arcuate Pomc neurons. We also demonstrate that the Ht2Cr agonist lorcaserin-induced improvements in glucose and insulin tolerance are blocked by TrpC5 deficiency in Pomc neurons. Together, our results link TrpC5 subunits in the brain with leptin- and serotonin 2C receptor-dependent changes in neuronal activity, as well as energy balance, feeding behavior, and glucose metabolism.

  17. Source-Coupled, N-Channel, JFET-Based Digital Logic Gate Structure Using Resistive Level Shifters

    Science.gov (United States)

    Krasowski, Michael J.

    2011-01-01

    A circuit topography is used to create usable, digital logic gates using N (negatively doped) channel junction field effect transistors (JFETs), load resistors, level shifting resistors, and supply rails whose values are based on the DC parametric distributions of these JFETs. This method has direct application to the current state-of-the-art in high-temperature (300 to 500 C and higher) silicon carbide (SiC) device production, and defines an adaptation to the logic gate described in U.S. Patent 7,688,117 in that, by removing the level shifter from the output of the gate structure described in the patent (and applying it to the input of the same gate), a source-coupled gate topography is created. This structure allows for the construction AND/OR (sum of products) arrays that use far fewer transistors and resistors than the same array as constructed from the gates described in the aforementioned patent. This plays a central role when large multiplexer constructs are necessary; for example, as in the construction of memory. This innovation moves the resistive level shifter from the output of the basic gate structure to the front as if the input is now configured as what would be the output of the preceding gate, wherein the output is the two level shifting resistors. The output of this innovation can now be realized as the lone follower transistor with its source node as the gate output. Additionally, one may leave intact the resistive level shifter on the new gate topography. A source-coupled to direct-coupled logic translator will be the result.

  18. The conserved potassium channel filter can have distinct ion binding profiles: structural analysis of rubidium, cesium, and barium binding in NaK2K.

    Science.gov (United States)

    Lam, Yee Ling; Zeng, Weizhong; Sauer, David Bryant; Jiang, Youxing

    2014-08-01

    Potassium channels are highly selective for K(+) over the smaller Na(+). Intriguingly, they are permeable to larger monovalent cations such as Rb(+) and Cs(+) but are specifically blocked by the similarly sized Ba(2+). In this study, we used structural analysis to determine the binding profiles for these permeant and blocking ions in the selectivity filter of the potassium-selective NaK channel mutant NaK2K and also performed permeation experiments using single-channel recordings. Our data revealed that some ion binding properties of NaK2K are distinct from those of the canonical K(+) channels KcsA and MthK. Rb(+) bound at sites 1, 3, and 4 in NaK2K, as it does in KcsA. Cs(+), however, bound predominantly at sites 1 and 3 in NaK2K, whereas it binds at sites 1, 3, and 4 in KcsA. Moreover, Ba(2+) binding in NaK2K was distinct from that which has been observed in KcsA and MthK, even though all of these channels show similar Ba(2+) block. In the presence of K(+), Ba(2+) bound to the NaK2K channel at site 3 in conjunction with a K(+) at site 1; this led to a prolonged block of the channel (the external K(+)-dependent Ba(2+) lock-in state). In the absence of K(+), however, Ba(2+) acts as a permeating blocker. We found that, under these conditions, Ba(2+) bound at sites 1 or 0 as well as site 3, allowing it to enter the filter from the intracellular side and exit from the extracellular side. The difference in the Ba(2+) binding profile in the presence and absence of K(+) thus provides a structural explanation for the short and prolonged Ba(2+) block observed in NaK2K. © 2014 Lam et al.

  19. Pulse radiolysis studies of intramolecular electron transfer in model peptides and proteins. 7. Trp -> TyrO radical transformation in hen egg-white lysozyme. Effects of pH, temperature, Trp62 oxidation and inhibitor binding

    DEFF Research Database (Denmark)

    Bobrowski, K.; Holcman, J.; Poznanski, J.

    1997-01-01

    by ozone had a pronounced effect on its temperature-dependence. Taken together these observations indicate that of the six tryptophans present in HEWL Trp62 contributes about 50% to the yield of the observed LRET. In the enzyme-inhibitor complex, HEWL(GlcNAc)(3), where Trp62 and Trp63 are completely...... oxidation of Trp with N-3(.) radicals under low concentration of the reactants but at a high HEWL/N-3(.) molar ratio, so that more than 99% of the oxidized protein molecules contained only a single tryptophyl radical. Synchronous decay of Trp(.) and build-up of TyrO(.) conformed satisfactorily to first......-order kinetics, indicating that LRET involved either one or more Trp(.)/Tyr redox pairs characterized by similar rate constants. The rate constant of LRET, k(5), increased monotonously with decreasing pH showing the following characteristics: (i) in the pH range 7.4-5.2 the plot of k(5) against pH was sigmoidal...

  20. Enhancement-mode two-channel triple quantum dot from an undoped Si/Si0.8Ge0.2 quantum well hetero-structure.

    Energy Technology Data Exchange (ETDEWEB)

    Studenikin, S. A.; Gaudreau, L.; Kataoka, K.; Austing, D. G.; Lu, Tzu-Ming; Luhman, Dwight; Bethke, Donald Thomas; Wanke, Michael; Lilly, Michael; Carroll, Malcolm S.; Sachrajda, A. S.

    2017-12-01

    We demonstrate coupled triple dot operation and charge sensing capability for the recently introduced quantum dot technology employing undoped Si/Si0.8Ge0.2 hetero-structures which also incorporate a single metal-gate layer to simplify fabrication [T. M. Lu et al., Appl. Phys. Lett. 109, 093102 (2016)]. Si/SiGe hetero-structures with a Ge concentration of 20% rather than the more usual 30% typically encountered offer higher electron mobility. The devices consist of two in-plane parallel electron channels that host a double dot in one channel and a single dot in the other channel. In a device where the channels are sufficiently close a triple dot in a triangular configuration is induced leading to regions in the charge stability diagram where three addition lines of different slope approach each other and anti-cross. In a device where the channels are further apart the single dot charge-senses the double dot with relative change of ~2% in the sensor current. We also highlight temporal drifting and metastability of the Coulomb oscillations. These effects are induced if the temperature environment of the device is not kept constant and arise from non-equilibrium charge redistribution and subsequent slow recovery.

  1. Atomic basis for therapeutic activation of neuronal potassium channels

    DEFF Research Database (Denmark)

    Kim, Robin Y; Yau, Michael C; Galpin, Jason D

    2015-01-01

    with fluorinated Trp analogues, with increased H-bonding propensity, strengthens retigabine potency. In addition, potency of numerous retigabine analogues correlates with the negative electrostatic surface potential of a carbonyl/carbamate oxygen atom present in most KCNQ activators. These findings functionally...... pinpoint an atomic-scale interaction essential for effects of retigabine and provide stringent constraints that may guide rational improvement of the emerging drug class of KCNQ channel activators....

  2. Towards a model of source and channel choices in business-to-government service interactions : A structural equation modeling approach

    NARCIS (Netherlands)

    van den Boer, Yvon; Pieterson, Willem; Arendsen, Rex; van Dijk, Jan

    With a growing number of available communication channels and the increasing role of other information sources, organizations are urged to rethink their service strategies. Most theories are limited to a one-dimensional focus on source or channel choice and do not fit into today's networked

  3. Game Theoretic Analysis of Carbon Emission Abatement in Fashion Supply Chains Considering Vertical Incentives and Channel Structures

    Directory of Open Access Journals (Sweden)

    Longfei He

    2015-04-01

    Full Text Available We study an emission-dependent dyadic fashion supply chain made up of a supplier and a manufacturer, both of which can reduce their own component/product emissions to serve the carbon-footprint sensitive consumers. With Carbon Tax regulation, we consider four scenarios resulting from two ways in form of adopting transfer price contract and/or introducing third-party emission-reduction service (TPERS to enhance the efficiency of systematic emission reductions. We refine four models from these corresponding scenarios, which in turn constitute a decision-making framework composed of determining vertical incentives and choosing supply chain structures. By exploiting Stackelberg games in all models, we compare their emission reduction efficiencies and profitability for each pair of settings. Theoretic analysis and numerical studies show that adopting vertical transfer payment schemes can definitely benefit channel carbon footprint reduction and Pareto improvement of supply chain profitability, regardless of whether the emission-reduction service exists or not. However, whether introducing TPERS or not is heavily depending on systematic parameters when the transfer payment incentive is adopted there. We also provide insights on the sensitivity of carbon tax parameters with respect to the supply chain performance, overall carbon emission reduction, vertical incentive and TPERS adopting decision-makings.

  4. NMR assignments for the amino-terminal residues of trp repressor and their role in DNA binding

    International Nuclear Information System (INIS)

    Arrowsmith, C.H.; Carey, J.; Treat-Clemons, L.; Jardetzky, O.

    1989-01-01

    The trp repressor of Escherichia coli specifically binds to operator DNAs in three operons involved in tryptophan metabolism. The NMR spectra of repressor and a chymotryptic fragment lacking the six amino-terminal residues are compared. Two-dimensional J-correlated spectra of the two forms of the protein are superimposable except for cross-peaks that are associated with the N-terminal region. The chemical shifts and relaxation behavior of the N-terminal resonances suggest mobile arms. Spin-echo experiments on a ternary complex of repressor with L-tryptophan and operator DNA indicate that the termini are also disordered in the complex, although removal of the arms reduces the DNA binding energy. Relaxation measurements on the armless protein show increased mobility for several residues, probably due to helix fraying in the newly exposed N-terminal region. DNA binding by the armless protein does not reduce the mobility of these residues. Thus, it appears that the arms serve to stabilize the N-terminal helix but that this structural role does not explain their contribution to the DNA binding energy. These results suggest that the promiscuous DNA binding by the arms seen in the X-ray crystal structure is found in solution as well

  5. Structural safety of coolant channel components under excessively high pressure tube diametral expansion rate at garter spring location

    Energy Technology Data Exchange (ETDEWEB)

    Aravind, M. [Reactor Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Sinha, S.K., E-mail: sunilks@barc.gov.in [Reactor Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2013-08-15

    Structural safety of coolant channel assembly in the event of high diametral expansion of pressure tube in a 220 MWe pressurised heavy water reactor was investigated using axisymmetric and 3-D finite element models. The axisymmetric analyses were performed and stresses were evaluated for pressure tube, girdle wire and calandria tube at different point of time for diametral expansion rates of 0.2%, 0.25% and 0.3% per year of the pressure tube inside diameter. The results of this study indicated that for the case of 0.3% per year of diametral expansion rate (worst case scenario), occurrence of complete circumferential interference of garter spring with calandria tube at the location of maximum expansion would take place much earlier at around 14 years or 4.2% of the total expansion of pressure tube as opposed to its anticipated design life (30 years). This fact was further corroborated by 3-D finite element analysis performed for the actual assembly configuration under actual loadings. The latter analysis revealed that net section yielding of calandria tube occurs in just 1 year after the occurrence of total circumferential interference between calandria tube and garter spring spacer. It has also been observed that the maximum stress intensity in girdle wire does not increase beyond the ultimate tensile strength even when maximum stress intensity in calandria tube reaches its yield strength. These analyses also revealed that the structural as well as functional integrity of pressure tube and the garter spring is not affected as result of this interference.

  6. Structural safety of coolant channel components under excessively high pressure tube diametral expansion rate at garter spring location

    Science.gov (United States)

    Aravind, M.; Sinha, S. K.

    2013-08-01

    Structural safety of coolant channel assembly in the event of high diametral expansion of pressure tube in a 220 MWe pressurised heavy water reactor was investigated using axisymmetric and 3-D finite element models. The axisymmetric analyses were performed and stresses were evaluated for pressure tube, girdle wire and calandria tube at different point of time for diametral expansion rates of 0.2%, 0.25% and 0.3% per year of the pressure tube inside diameter. The results of this study indicated that for the case of 0.3% per year of diametral expansion rate (worst case scenario), occurrence of complete circumferential interference of garter spring with calandria tube at the location of maximum expansion would take place much earlier at around 14 years or 4.2% of the total expansion of pressure tube as opposed to its anticipated design life (30 years). This fact was further corroborated by 3-D finite element analysis performed for the actual assembly configuration under actual loadings. The latter analysis revealed that net section yielding of calandria tube occurs in just 1 year after the occurrence of total circumferential interference between calandria tube and garter spring spacer. It has also been observed that the maximum stress intensity in girdle wire does not increase beyond the ultimate tensile strength even when maximum stress intensity in calandria tube reaches its yield strength. These analyses also revealed that the structural as well as functional integrity of pressure tube and the garter spring is not affected as result of this interference.

  7. Transient receptor potential (TRP) A1 activated currents in TRPV1 and cholecystokinin-sensitive cranial visceral afferent neurons.

    Science.gov (United States)

    Choi, Myung-Jin; Jin, Zhenhua; Park, Yong Seek; Rhee, Young Kyoung; Jin, Young-Ho

    2011-04-06

    Culinary use of the pungent spices has potential health benefits including a reduction in food intake. Pungent spices often contain ingredients that activate members of the transient receptor potential (TRP) family A1 and evoke pain from capsaicin-sensitive somatosensory neurons. TRPA1 channel have also been identified on cranial visceral afferent neurons but their distribution and functional contributions are poorly understood. Visceral vagal neurons transduce mechanical and chemical signals from peripheral organs to the nucleus tractus solitarii. Many capsaicin-sensitive vagal afferents participate in peripheral satiety signaling that includes cholecystokinin (CCK) sensitive neurons. To assess signaling, the TRPA1 selective agonist allyl isothiocyanate (AITC) was tested together with CCK and capsaicin (200nM), a TRPV1 specific agonist. In isolated nodose neurons, AITC (0.05-0.2mM) evoked concentration-dependent inward currents in 38% of the tested neurons. The TRPA1 specific antagonist HC-030031 (10μM) blocked AITC responses. TRPA1 responses were mixed across neurons that were capsaicin-sensitive and -insensitive. However CCK evoked inward currents only on capsaicin-sensitive neurons and 28% of the CCK-sensitive neurons expressed TRPA1. Our results indicate that TRPA1 is co-expressed with TRPV1 in CCK-sensitive nodose neurons. The findings indicate a potential mechanism by which spices can act within cranial visceral afferent pathways mediating satiety and contribute to the reduction of the food intake associated with spiced diets. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. DETAILS OF OPERATIONS PERFORMED BY THE REMOTE CONTROL ROBOT (CONCEPT TO THE HORIZONTAL FUEL CHANNEL DURING DECOMMISSIONING PHASE OF NUCLEAR REACTOR CALANDRIA STRUCTURE. PART I: OUTSIDE OPERATIONS

    Directory of Open Access Journals (Sweden)

    Constantin POPESCU

    2017-05-01

    Full Text Available The authors contribution to this paper is to present a concept solution of a remote control robot (RCR used for the horizontal fuel channels pressure tube decommissioning in the CANDU nuclear reactor. The authors highlight in this paper, few details of geometry, operations, constraints by kinematics and dynamics of the robot movement outside of the reactor fuel channel. Outside operations performed has as the main steps of dismantling process the followings: positioning front of Calandria structure at the fuel channel to be decommissioned, coupling and locking to the End Fitting (EF, sorting and storage extracted items in the safe container. All steps are performed in automatic mode. The remote control robot (RCR represents a safety system controlled by sensors and has the capability to analyze any error registered and decide next activities or abort the outside decommissioning procedure in case of any risk rise in order to ensure the environmental and workers protection.

  9. The human transient receptor potential vanilloid 3 channel is sensitized via the ERK pathway

    Czech Academy of Sciences Publication Activity Database

    Vyklická, Lenka; Boukalová, Štěpána; Mačíková, Lucie; Chvojka, Štěpán; Vlachová, Viktorie

    2017-01-01

    Roč. 292, č. 51 (2017), s. 21083-21091 ISSN 0021-9258 R&D Projects: GA ČR(CZ) GA15-15839S Institutional support: RVO:67985823 Keywords : epidermal growth factor receptor (EGFR) * extracellular-signal-regulated kinase (ERK) * keratinocyte * phosphorylation * transient receptor potential channels * TRP channels Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology Impact factor: 4.125, year: 2016

  10. Inhibitory effects of imperatorin on voltage-gated K(+) channels and ATP-sensitive K(+) channels.

    Science.gov (United States)

    Wang, Yu-Wen; Yang, Chin-Tsang; Chen, Yi-Hung; Gong, Chi-Li; Chen, Yu-Fang; Kuo, Yueh-Hsiung; Leung, Yuk-Man

    2015-02-01

    Imperatorin is a furocoumarin isolated from Angelica archangelica and Cnidium monnieri. It has multiple neuromodulatory actions such as anticonvulsant effects, anxiolytic effects and anti-nociceptive effects. Although there have been reports demonstrating its effects on voltage-gated Na(+) channels (VGSC) and transient reversal potential (TRP) V1 channels in neurons, there is hitherto no work showing whether this compound affects voltage-gated K(+) (Kv) channels and ATP-sensitive K(+) (KATP) channels. We investigated the effects of imperatorin on K(+) channels using whole-cell configuration voltage-clamp technique. Imperatorin inhibited Kv channels in differentiated neuronal NG108-15 cells, and caused a left shift in the steady-state inactivation curve without affecting activation gating. Imperatorin also inhibited heterologously expressed wild type Kv1.2 and Kv2.1 channels, but became much less potent in inhibiting Kv1.2 V370G, a mutant defective in C-type inactivation, implying that drug inhibition depends on C-type inactivation. At a high concentration (100μM), imperatorin also suppressed KATP channels. Our results suggest that imperatorin inhibited both Kv and KATP channels. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  11. Volume of the space of qubit-qubit channels and state transformations under random quantum channels

    OpenAIRE

    Lovas, Attila; Andai, Attila

    2017-01-01

    The simplest building blocks for quantum computations are the qubit-qubit quantum channels. In this paper, we analyze the structure of these channels via their Choi representation. The restriction of a quantum channel to the space of classical states (i.e. probability distributions) is called the underlying classical channel. The structure of quantum channels over a fixed classical channel is studied, the volume of general and unital qubit channels with respect to the Lebesgue measure is comp...

  12. A Common Structural Component for β-Subunit Mediated Modulation of Slow Inactivation in Different KV Channels

    DEFF Research Database (Denmark)

    Strutz-Seebohm, Nathalie; Henrion, Ulrike; Schmitt, Nicole

    2013-01-01

    Background/Aims: Potassium channels are tetrameric proteins providing potassium selective passage through lipid embedded proteinaceous pores with highest fidelity. The selectivity results from binding to discrete potassium binding sites and stabilization of a hydrated potassium ion in a central...

  13. A structural, functional, and computational analysis suggests pore flexibility as the base for the poor selectivity of CNG channels.

    Science.gov (United States)

    Napolitano, Luisa Maria Rosaria; Bisha, Ina; De March, Matteo; Marchesi, Arin; Arcangeletti, Manuel; Demitri, Nicola; Mazzolini, Monica; Rodriguez, Alex; Magistrato, Alessandra; Onesti, Silvia; Laio, Alessandro; Torre, Vincent

    2015-07-07

    Cyclic nucleotide-gated (CNG) ion channels, despite a significant homology with the highly selective K(+) channels, do not discriminate among monovalent alkali cations and are permeable also to several organic cations. We combined electrophysiology, molecular dynamics (MD) simulations, and X-ray crystallography to demonstrate that the pore of CNG channels is highly flexible. When a CNG mimic is crystallized in the presence of a variety of monovalent cations, including Na(+), Cs(+), and dimethylammonium (DMA(+)), the side chain of Glu66 in the selectivity filter shows multiple conformations and the diameter of the pore changes significantly. MD simulations indicate that Glu66 and the prolines in the outer vestibule undergo large fluctuations, which are modulated by the ionic species and the voltage. This flexibility underlies the coupling between gating and permeation and the poor ionic selectivity of CNG channels.

  14. Structure-activity relationship study and discovery of indazole 3-carboxamides as calcium-release activated calcium channel blockers

    OpenAIRE

    Bai, Sha; Nagai, Masazumi; Koerner, Steffi K.; Veves, Aristidis; Sun, Lijun

    2016-01-01

    Aberrant activation of mast cells contributes to the development of numerous diseases including cancer, autoimmune disorders, as well as diabetes and its complications. The influx of extracellular calcium via the highly calcium selective calcium-release activated calcium (CRAC) channel controls mast cell functions. Intracellular calcium homeostasis in mast cells can be maintained via the modulation of the CRAC channel, representing a critical point for therapeutic interventions. We describe t...

  15. 3D Structural and Stratigraphic Architecture of the Northwest Santa Barbara Channel and Implications for Submarine Landslide Generation

    Science.gov (United States)

    Wright, A.; Kluesner, J. W.; Brothers, D. S.; Johnson, S. Y.

    2015-12-01

    Multiple submarine landslides have been previously documented on the north flank of the Santa Barbara Channel, and such failures are considered capable of generating local tsunamis. 2D seismic-reflection datasets provide a general view of regional framework geology, including faulting and folding associated with north-south compression. However, better understanding of the relationships between faults, folds, stratigraphic architecture, and submarine landslides can be obtained with 3D seismic datasets. In this study we use an industry 3D seismic-reflection volume that encompasses the slope and shelfbreak surrounding the Gaviota submarine landslide (3.8 km2) to investigate structural and stratigraphic controls on slope failure in this region. The depth-migrated seismic volume shows a network of stacked thrust faults, backthrusts, and splays that results in both broad and local zones of compression and folding along the slope and shelf. One localized zone of enhanced folding associated with small-offset thrust faults is located directly beneath the Gaviota landslide headwall, while another zone is located directly below an imaged seafloor fissure. In addition, 3D seismic attribute analysis provides insight into the shallow sedimentary section of the failed and non-failed sedimentary packages. Calculation of RMS amplitude and dominant frequency within a windowed region below the seafloor horizon delineates an apparent zone of gas-charged strata that onlaps onto older folded sediments. The up-dip limit of these gas-charged sediments aligns with the location of a seafloor fissure that extends westward from the Gaviota landslide headwall. We propose that the combination of deformation and fluid charging acted to pre-condition and trigger the failure of the Gaviota landslide, and as a result, the presence of these conditions along the fissure adjacent to the Gaviota landslide suggests this area should be considered landslide prone.

  16. Mechanisms underlying stage-1 TRPL channel translocation in Drosophila photoreceptors.

    Directory of Open Access Journals (Sweden)

    Minh-Ha Lieu

    Full Text Available TRP channels function as key mediators of sensory transduction and other cellular signaling pathways. In Drosophila, TRP and TRPL are the light-activated channels in photoreceptors. While TRP is statically localized in the signaling compartment of the cell (the rhabdomere, TRPL localization is regulated by light. TRPL channels translocate out of the rhabdomere in two distinct stages, returning to the rhabdomere with dark-incubation. Translocation of TRPL channels regulates their availability, and thereby the gain of the signal. Little, however, is known about the mechanisms underlying this trafficking of TRPL channels.We first examine the involvement of de novo protein synthesis in TRPL translocation. We feed flies cycloheximide, verify inhibition of protein synthesis, and test for TRPL translocation in photoreceptors. We find that protein synthesis is not involved in either stage of TRPL translocation out of the rhabdomere, but that re-localization to the rhabdomere from stage-1, but not stage-2, depends on protein synthesis. We also characterize an ex vivo eye preparation that is amenable to biochemical and genetic manipulation. We use this preparation to examine mechanisms of stage-1 TRPL translocation. We find that stage-1 translocation is: induced with ATP depletion, unaltered with perturbation of the actin cytoskeleton or inhibition of endocytosis, and slowed with increased membrane sterol content.Our results indicate that translocation of TRPL out of the rhabdomere is likely due to protein transport, and not degradation/re-synthesis. Re-localization from each stage to the rhabdomere likely involves different strategies. Since TRPL channels can translocate to stage-1 in the absence of ATP, with no major requirement of the cytoskeleton, we suggest that stage-1 translocation involves simple diffusion through the apical membrane, which may be regulated by release of a light-dependent anchor in the rhabdomere.

  17. Genomic and structural characterization of Kunitz-type peptide LmKTT-1a highlights diversity and evolution of scorpion potassium channel toxins.

    Directory of Open Access Journals (Sweden)

    Zongyun Chen

    Full Text Available BACKGROUND: Recently, a new subfamily of long-chain toxins with a Kunitz-type fold was found in scorpion venom glands. Functionally, these toxins inhibit protease activity and block potassium channels. However, the genomic organization and three-dimensional (3-D structure of this kind of scorpion toxin has not been reported. PRINCIPAL FINDINGS: Here, we characterized the genomic organization and 3-D nuclear magnetic resonance structure of the scorpion Kunitz-type toxin, LmKTT-1a, which has a unique cysteine pattern. The LmKTT-1a gene contained three exons, which were interrupted by two introns located in the mature peptide region. Despite little similarity to other Kunitz-type toxins and a unique pattern of disulfide bridges, LmKTT-1a possessed a conserved Kunitz-type structural fold with one α-helix and two β-sheets. Comparison of the genomic organization, 3-D structure, and functional data of known toxins from the α-KTx, β-KTx, γ-KTx, and κ-KTx subfamily suggested that scorpion Kunitz-type potassium channel toxins might have evolved from a new ancestor that is completely different from the common ancestor of scorpion toxins with a CSα/β fold. Thus, these analyses provide evidence of a new scorpion potassium channel toxin subfamily, which we have named δ-KTx. CONCLUSIONS/SIGNIFICANCE: Our results highlight the genomic, structural, and evolutionary diversity of scorpion potassium channel toxins. These findings may accelerate the design and development of diagnostic and therapeutic peptide agents for human potassium channelopathies.

  18. Thioredoxin Txnl1/TRP32 Is a Redox-active Cofactor of the 26 S Proteasome

    DEFF Research Database (Denmark)

    Andersen, Katrine M; Klausen, Louise Kjær; Prag, Søren

    2009-01-01

    The 26S proteasome is a large proteolytic machine, which degrades most intracellular proteins. We found that thioredoxin, Txnl1/TRP32, binds to Rpn11, a subunit of the regulatory complex of the human 26S proteasome. Txnl1 is abundant, metabolically stable and widely expressed and is present...... in the cytoplasm and nucleus. Txnl1 has thioredoxin activity with a redox potential of about -250 mV. Mutant Txnl1 with one active site cysteine replaced by serine formed disulfide bonds to eEF1A1, a substrate-recruiting factor of the 26S proteasome. eEF1A1 is therefore a likely physiological substrate...

  19. Thermo-sensitive TRP channels in peripheral nerve injury: a review of their role in cold intolerance

    NARCIS (Netherlands)

    Kambiz, S.; Duraku, L.S.; Holstege, J.C.; Hovius, S.E.; Ruigrok, T.J.; Walbeehm, E.T.

    2014-01-01

    One of the sensory complications of traumatic peripheral nerve injury is thermal intolerance, which manifests in humans mainly as cold intolerance. It has a major effect on the quality of life, and adequate therapy is not yet available. In order to better understand the pathophysiological background

  20. Sound response mediated by the TRP channels NOMPC, NANCHUNG, and INACTIVE in chordotonal organs of Drosophila larvae

    OpenAIRE

    Zhang, Wei; Yan, Zhiqiang; Jan, Lily Yeh; Jan, Yuh Nung

    2013-01-01

    Mechanical stimuli, including tactile and sound signals, convey a variety of information important for animals to navigate the environment and avoid predators. Recent studies have revealed that Drosophila larvae can sense harsh or gentle touch with dendritic arborization (da) neurons in the body wall and can detect vibration with chordotonal organs (Cho). Whether they can also detect and respond to vibration or sound from their predators remains an open question. Here we report that larvae re...

  1. Citral sensing by Transient [corrected] receptor potential channels in dorsal root ganglion neurons.

    Directory of Open Access Journals (Sweden)

    Stephanie C Stotz

    2008-05-01

    Full Text Available Transient receptor potential (TRP ion channels mediate key aspects of taste, smell, pain, temperature sensation, and pheromone detection. To deepen our understanding of TRP channel physiology, we require more diverse pharmacological tools. Citral, a bioactive component of lemongrass, is commonly used as a taste enhancer, as an odorant in perfumes, and as an insect repellent. Here we report that citral activates TRP channels found in sensory neurons (TRPV1 and TRPV3, TRPM8, and TRPA1, and produces long-lasting inhibition of TRPV1-3 and TRPM8, while transiently blocking TRPV4 and TRPA1. Sustained citral inhibition is independent of internal calcium concentration, but is state-dependent, developing only after TRP channel opening. Citral's actions as a partial agonist are not due to cysteine modification of the channels nor are they a consequence of citral's stereoisoforms. The isolated aldehyde and alcohol cis and trans enantiomers (neral, nerol, geranial, and geraniol each reproduce citral's actions. In juvenile rat dorsal root ganglion neurons, prolonged citral inhibition of native TRPV1 channels enabled the separation of TRPV2 and TRPV3 currents. We find that TRPV2 and TRPV3 channels are present in a high proportion of these neurons (94% respond to 2-aminoethyldiphenyl borate, consistent with our immunolabeling experiments and previous in situ hybridization studies. The TRPV1 activation requires residues in transmembrane segments two through four of the voltage-sensor domain, a region previously implicated in capsaicin activation of TRPV1 and analogous menthol activation of TRPM8. Citral's broad spectrum and prolonged sensory inhibition may prove more useful than capsaicin for allodynia, itch, or other types of pain involving superficial sensory nerves and skin.

  2. Comparative molecular modelling study of the calcium channel blockers nifedipine and black mamba toxin FS2

    Science.gov (United States)

    Schleifer, Klaus-Jürgen

    1997-09-01

    The identification and structural determination of the criticalamino acid residues causing the calcium channel blocking effects of theangusticeps type III toxin FS2 is described. Alignments withmore than 200 different short and long neuro-, cyto-, muscarinic and otherangusticeps-type toxins yielded 12 amino acid residues at the tips of loopsII and III which are unique to the type III toxins. The competitive bindingbehaviour between the 1,4-dihydropyridine derivative nifedipine and toxinFS2 was used for a further delimitation of the relevant toxinbinding domain. Using the ab initio geometry optimized nifedipine X-raystructure as a template, a model based on the sequenceMet45-Trp46-cis-Pro47-Tyr48has been elaborated. This sequence shows the same hydrophobic andhydrogen bond forming properties as nifedipine. In addition, qualitativelysimilar molecular electrostatic potentials are observed for both structures,leading to the assumption that these amino acid residues of the toxin act asthe potential attachment region at the calcium channel receptor site.

  3. Adding efficiency: the role of the CAN ion channels TRPM4 and TRPM5 in pancreatic islets.

    Science.gov (United States)

    Enklaar, Thorsten; Brixel, Lili R; Zabel, Bernhard U; Prawitt, Dirk

    2010-01-01

    Insulin secretion in β-pancreatic cells after glucose stimulation requires the concerted action of a number of different ion channels. The main players seem to be the ATP sensitive K(+) (KATP-) channels, and voltage gated ion channels that drive Ca(2+) influx into β-cells. Recently two calcium activated nonselective (CAN) cation channels (TRPM4 and TRPM5) have been shown to influence efficient insulin response upon glucose stimulation. This addendum summarizes the data known for these two TRP channels in β-cells, discusses some of the remaining open questions and addresses a possible scenario that involves and integrates the triggering and amplifying pathway of glucose mediated insulin secretion.

  4. Distinct modulation of inactivation by a residue in the pore domain of voltage-gated Na+channels: mechanistic insights from recent crystal structures.

    Science.gov (United States)

    Cervenka, Rene; Lukacs, Peter; Gawali, Vaibhavkumar S; Ke, Song; Koenig, Xaver; Rubi, Lena; Zarrabi, Touran; Hilber, Karlheinz; Sandtner, Walter; Stary-Weinzinger, Anna; Todt, Hannes

    2018-01-12

    Inactivation of voltage-gated Na + channels (VGSC) is essential for the regulation of cellular excitability. The molecular rearrangement underlying inactivation is thought to involve the intracellular linker between domains III and IV serving as inactivation lid, the receptor for the lid (domain III S4-S5 linker) and the pore-lining S6 segements. To better understand the role of the domain IV S6 segment in inactivation we performed a cysteine scanning mutagenesis of this region in rNav 1.4 channels and screened the constructs for perturbations in the voltage-dependence of steady state inactivation. This screen was performed in the background of wild-type channels and in channels carrying the mutation K1237E, which profoundly alters both permeation and gating-properties. Of all tested constructs the mutation I1581C was unique in that the mutation-induced gating changes were strongly influenced by the mutational background. This suggests that I1581 is involved in specific short-range interactions during inactivation. In recently published crystal structures VGSCs the respective amino acids homologous to I1581 appear to control a bend of the S6 segment which is critical to the gating process. Furthermore, I1581 may be involved in the transmission of the movement of the DIII voltage-sensor to the domain IV S6 segment.

  5. STEREOVIDEO YouTube channel: Short educational videos for the on-line learning of the stereographic projection technique in Structural Geology

    Science.gov (United States)

    Insua-Arevalo, Juan M.; Alvarez-Gomez, Jose A.; Castiñeiras, Pedro; Tejero-Lopez, Rosa; Martinez-Diaz, Jose J.; Rodriguez-Peces, Martin J.

    2017-04-01

    STEREOVIDEO channel (https://www.youtube.com/user/geostereovideo) is a YouTube channel of short educational videos (learning the handling of the stereographic projection technique applied to Structural Geology (also to Engineering Geology). This type of videos aims to reinforce the traditional classroom lessons with the use of communication technologies resources. Such a reinforcing facilitates the possibility to deepen more on conceptual aspects once the students dominate the representation tool helping them to develop their own critical thinking skills. After three years of being launched on-line (on 2014), we analyze the broadcast and acceptance of the channel by the academic community. For this purpose we have taken into account two different sources: (1) the analytics tool from YouTube (subscriptions, views, countries, comments from the users, type of device for viewing), and (2) our own survey among users (students and teachers) to get their opinion about the videos. By January, 2017 (date of sending of this abstract), the channel has a total of 650 subscriptions, with more than 85,000 views all around the world, mainly in Spanish speaking countries (as the videos are in Spanish). The main devices for viewing the videos are PCs, but is noteworthy the use of smart phones and tablets. The video users, both students and teachers, value this type of content positively.

  6. Activation of the Chemosensory Ion Channels TRPA1 and TRPV1 by Hydroalcohol Extract of Kalopanax pictus Leaves.

    Science.gov (United States)

    Son, Hee Jin; Kim, Yiseul; Misaka, Takumi; Noh, Bong Soo; Rhyu, Mee-Ra

    2012-11-01

    TRPA1 and TRPV1 are members of the TRP superfamily of structurally related, nonselective cation channels. TRPA1 and TRPV1 are often co-expressed in sensory neurons and play an important role in somatosense such as cold, pain, and irritants. The first leaves of Kalopanax pictus Nakai (Araliaceae) have long been used as a culinary ingredient in Korea because of their unique chemesthetic flavor. In this study, we observed the intracellular Ca(2+) response to cultured cells expressing human TRPA1 (hTRPA1) and human TRPV1 (hTRPV1) by Ca(2+) imaging analysis to investigate the ability of the first leaves of K. pictus to activate the hTRPA1 and hTRPV1. An 80% ethanol extract of K. pictus (KPEx) increased intracellular Ca(2+) influx in a response time- and concentration-dependent manner via either hTRPA1 or hTRPV1. KPEx-induced response to hTRPA1 was markedly attenuated by ruthenium red, a general blocker of TRP channels, and HC-030031, a specific antagonist of TRPA1. In addition, the intracellular Ca(2+) influx attained with KPEx to hTRPV1 was mostly blocked by ruthenium red, and capsazepine, a specific antagonist of TRPV1. These results indicate that KPEx selectively activates both hTRPA1 and hTRPV1, which may provide evidence that the first leaves of K. pictus primarily activate TRPA1 and TRPV1 to induce their unique chemesthetic sense.

  7. Structural properties of as-grown and reduced Pr2CuO4 single crystals investigated by ion channeling

    International Nuclear Information System (INIS)

    Haga, T.; Abe, Y.

    1996-01-01

    Ion channeling is very sensitive to atomic arrangements and small atomic displacements in real space. Thus, in order to clarify a role of reduction for Pr 2 CuO 4 , ion channeling properties for the materials have been measured in detail. Anomalous increases of dechanneling fractions of Cu and O atoms in the reduced samples have been found. These results could not be explained by the apical oxygen model but probably suggest that O atoms in Cu-O planes are removed by reduction. Taking these results into account, correlation between lattice instability and superconductivity in the material will be discussed. (orig.)

  8. Human Digital Meissner Corpuscles Display Immunoreactivity for the Multifunctional Ion Channels Trpc6 and Trpv4.

    Science.gov (United States)

    Alonso-González, Paula; Cabo, Roberto; San José, Isabel; Gago, Angel; Suazo, Iván C; García-Suárez, Olivia; Cobo, Juan; Vega, José A

    2017-06-01

    Ion channels are at the basis of the sensory processes including mechanosensing. Some members of the transient receptor potential (TRP) ion channel superfamily have been proposed as mechanosensors, but their putative role in mechanotransduction is controversial. Among them there are TRP canonical 6 (TRPC6) and TRP vanilloid 4 (TRPV4) ion channels, which are known to cooperate in mechanical hyperalgesia. Here, we investigated the occurrence, distribution, and possible colocalization of TRPC6 and TRPV4 in human digital Meissner sensory corpuscles using immunohistochemistry and double immunofluorescence (associate with markers for specific corpuscular constituents). TRPC6 immunoreactivity was restricted to the axon of Meissner corpuscles, whereas TRPV4 was detected in the axon but also in the lamellar cells. Moreover, axonal colocalization of TRPV4 and TRPC6 was found in the digital Meissner corpuscles. Present results demonstrate for the first time the occurrence and colocalization of two ion channels candidates to mechanosensors in human cutaneous mechanoreceptors. The functional significance of these ion channels in that place remains to be clarified, but should be related to different properties of mechanosensitivity. Anat Rec, 300:1022-1031, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  9. Ehrlichia chaffeensis TRP120 Activates Canonical Notch Signaling To Downregulate TLR2/4 Expression and Promote Intracellular Survival

    Directory of Open Access Journals (Sweden)

    Taslima T. Lina

    2016-07-01

    Full Text Available Ehrlichia chaffeensis preferentially targets mononuclear phagocytes and survives through a strategy of subverting innate immune defenses, but the mechanisms are unknown. We have shown E. chaffeensis type 1 secreted tandem repeat protein (TRP effectors are involved in diverse molecular pathogen-host interactions, such as the TRP120 interaction with the Notch receptor-cleaving metalloprotease ADAM17. In the present study, we demonstrate E. chaffeensis, via the TRP120 effector, activates the canonical Notch signaling pathway to promote intracellular survival. We found that nuclear translocation of the transcriptionally active Notch intracellular domain (NICD occurs in response to E. chaffeensis or recombinant TRP120, resulting in upregulation of Notch signaling pathway components and target genes notch1, adam17, hes, and hey. Significant differences in canonical Notch signaling gene expression levels (>40% were observed during early and late stages of infection, indicating activation of the Notch pathway. We linked Notch pathway activation specifically to the TRP120 effector, which directly interacts with the Notch metalloprotease ADAM17. Using pharmacological inhibitors and small interfering RNAs (siRNAs against γ-secretase enzyme, Notch transcription factor complex, Notch1, and ADAM17, we demonstrated that Notch signaling is required for ehrlichial survival. We studied the downstream effects and found that E. chaffeensis TRP120-mediated activation of the Notch pathway causes inhibition of the extracellular signal-regulated kinase 1/2 (ERK1/2 and p38 mitogen-activated protein kinase (MAPK pathways required for PU.1 and subsequent Toll-like receptor 2/4 (TLR2/4 expression. This investigation reveals a novel mechanism whereby E. chaffeensis exploits the Notch pathway to evade the host innate immune response for intracellular survival.

  10. Secondary structure, stability and tetramerisation of recombinant Kv1.1 potassium channel cytoplasmic N-terminal fragment.

    NARCIS (Netherlands)

    Abbott, G.W.; Bloemendal, M.; van Stokkum, I.H.M.; Mercer, E.A.J.; Miller, R.T.; Sewing, S.; Wolters, M.J.J.; Pongs, O.; Srai, S.K.S.

    1997-01-01

    The recombinant N-terminal fragment (amino acids 14-162) of a tetrameric voltage-gated potassium channel (K(V)1.1) has been studied using spectroscopic techniques. Evidence is presented that it forms a tetramer in aqueous solution, whereas when solubilised in 1% Triton X-100 it remains monomeric.

  11. Structural Insights into the Function of P2X4: An ATP-Gated Cation Channel of Neuroendocrine Cells

    Czech Academy of Sciences Publication Activity Database

    Stojilkovic, S. S.; Yan, Z.; Obšil, T.; Zemková, Hana

    2010-01-01

    Roč. 30, č. 8 (2010), s. 1251-1258 ISSN 0272-4340 R&D Projects: GA AV ČR(CZ) IAA500110910; GA AV ČR(CZ) IAA501110801 Institutional research plan: CEZ:AV0Z50110509 Keywords : ATP-gated receptor channels * gating * ivermectin Subject RIV: ED - Physiology Impact factor: 2.423, year: 2010

  12. Structure of two-phase adiabatic flow in air sparging regime in vertical cylindrical channel with water

    Directory of Open Access Journals (Sweden)

    V. I. Solonin

    2014-01-01

    Full Text Available The article presents a research of two-phase adiabatic flow in air sparging regime in vertical cylindrical channel filled with water. A purpose of the work is to obtain experimental data for further analysis of a character of the moving phases. Research activities used the optic methods PIV (Particle Image Visualization because of their noninvasiveness to obtain data without disturbing effect on the flow. A laser sheet illuminated the fluorescence particles, which were admixed in water along the channel length. A digital camera recorded their motion for a certain time interval that allowed building the velocity vector fields. As a result, gas phase velocity components typical for a steady area of the channel and their relations for various intensity of volume air rate were obtained. A character of motion both for an air bubble and for its surrounding liquid has been conducted. The most probable direction of phases moving in the channel under sparging regime is obtained by building the statistic scalar fields. The use of image processing enabled an analysis of the initial area of the air inlet into liquid. A characteristic curve of the bubbles offset from the axis for various intensity of volume gas rate and channel diameter is defined. A character of moving phases is obtained by building the statistic scalar fields. The values of vertical components of liquid velocity in the inlet part of channel are calculated. Using the obtained data of the gas phase velocities a true void fraction was calculated. It was compared with the values of void fraction, calculated according to the liquid level change in the channel. Obtained velocities were compared with those of the other researchers, and a small difference in their values was explained by experimental conditions. The article is one of the works to research the two-phase flows with no disturbing effect on them. Obtained data allow us to understand a character of moving the two-phase flows in

  13. Structural characterization of an enantiopure hydroxo-bridged binuclear iron(III) complex with empty one-dimensional helical channels.

    Science.gov (United States)

    Alam, Md Akhtarul; Nethaji, Munirathinum; Ray, Manabendra

    2005-03-07

    A H-bond capable chiral tetradentate ligand, Fe3+, and acetate ion assembles into a hydroxo-bridged binuclear complex with the formula [FeIII2(mu-OH)(mu-OAc)(S-L)2] x 4H2O (1) where H2S-L = S-2-(2-hydroxy-benzylamino)-3-(1H-imidazol-4-yl)-propionic acid. The crystal of 1 contains right-handed one-dimensional (1D) helical channels with 7.3-9.8 A diameter. A similar reaction with a ligand having opposite chirality forms the complex with left-handed helical channels (1a). Heating the crystals of 1 at 95 degrees C under reduced pressure selectively removes three waters from the channel forming an enantiopure porous crystal with empty channels (solvent accessible voids 18% v/v). Intermolecular hydrogen bonding between the imidazole N-H and phenolate oxygen in 1-2 forms a C6 symmetric helix with bridging hydroxo groups pointing inside the channels. All the H-bond capable atoms in the ligand along with one water molecule form an extended H-bonded network throughout the crystal. Exposing the empty channels of 2 to iodine vapor indicates partial filling of the channels with iodine. Crystal data for 1 x 4H2O include the following: hexagonal, P61, a = b = 13.164(3) A, c = 36.305 (11) A, alpha = beta = 90 degrees , gamma = 120 degrees , Z = 6, R1 = 0.0387, wR2 = 0.0842. Crystal data for 1a x 2H2O include the following: hexagonal, P6(5), a = b = 13.151(4) A, c = 36.558(2) A, alpha = beta = 90 degrees , gamma = 120 degrees , Z = 6, R1 = 0.0416, wR2 = 0.1190. Crystal data for 2 x H2O include the following: hexagonal, P61, a = b = 13.160(7) A, c = 36.559 (4) A, alpha = beta = 90 degrees , gamma = 120 degrees , Z = 6, R1 = 0.0574, wR2 = 0.1423.

  14. An in-depth analysis of the biological functional studies based on the NMR M2 channel structure of influenza A virus

    International Nuclear Information System (INIS)

    Huang Ribo; Du Qishi; Wang Chenghua; Chou, K.-C.

    2008-01-01

    The long-sought three-dimensional structure of the M2 proton channel of influenza A virus was successfully determined recently by the high-resolution NMR [J.R. Schnell, J.J. Chou, Structure and mechanism of the M2 proton channel of influenza A virus, Nature 451 (2008) 591-595]. Such a milestone work has provided a solid structural basis for studying drug-resistance problems. However, the action mechanism revealed from the NMR structure is completely different from the traditional view and hence prone to be misinterpreted as 'conflicting' with some previous biological functional studies. To clarify this kind of confusion, an in-depth analysis was performed for these functional studies, particularly for the mutations D44N, D44A and N44D on position 44, and the mutations on positions 27-38. The analyzed results have provided not only compelling evidences to further validate the NMR structure but also very useful clues for dealing with the drug-resistance problems and developing new effective drugs against H5N1 avian influenza virus, an impending threat to human beings.

  15. NIR luminescent Er3+/Yb3+ co-doped SiO2–ZrO2 nanostructured planar and channel waveguides: Optical and structural properties

    International Nuclear Information System (INIS)

    Cunha, César dos Santos; Ferrari, Jefferson Luis; Oliveira, Drielly Cristina de; Maia, Lauro June Queiroz; Gomes, Anderson Stevens Leonidas; Ribeiro, Sidney José Lima

    2012-01-01

    Optical and structural properties of planar and channel waveguides based on sol–gel Er 3+ and Yb 3+ co-doped SiO 2 –ZrO 2 are reported. Microstructured channels with high homogeneous surface profile were written onto the surface of multilayered densified films deposited on SiO 2 /Si substrates by a femtosecond laser etching technique. The densification of the planar waveguides was evaluated from changes in the refractive index and thickness, with full densification being achieved at 900 °C after annealing from 23 up to 500 min, depending on the ZrO 2 content. Crystal nucleation and growth took place together with densification, thereby producing transparent glass ceramic planar waveguides containing rare earth-doped ZrO 2 nanocrystals dispersed in a silica-based glassy host. Low roughness and crack-free surface as well as high confinement coefficient were achieved for all the compositions. Enhanced NIR luminescence of the Er 3+ ions was observed for the Yb 3+ -codoped planar waveguides, denoting an efficient energy transfer from the Yb 3+ to the Er 3+ ion. Highlights: ► Sol–gel high NIR luminescent nanostructured planar and channel waveguides. ► Microstructured channels written by a femtosecond laser etching technique. ► Transparent glass ceramic with rare earth-doped ZrO 2 nanocrystals in a silica host. ► Enhanced NIR luminescence, efficient energy transfer from the Yb 3+ to the Er 3+ ion. ► New planar channel waveguides to be applied as EDWA in the C telecommunication band.

  16. Structural Analysis and Deletion Mutagenesis Define Regions of QUIVER/SLEEPLESS that Are Responsible for Interactions with Shaker-Type Potassium Channels and Nicotinic Acetylcholine Receptors.

    Directory of Open Access Journals (Sweden)

    Meilin Wu

    Full Text Available Ly6 proteins are endogenous prototoxins found in most animals. They show striking structural and functional parallels to snake α-neurotoxins, including regulation of ion channels and cholinergic signaling. However, the structural contributions of Ly6 proteins to regulation of effector molecules is poorly understood. This question is particularly relevant to the Ly6 protein QUIVER/SLEEPLESS (QVR/SSS, which has previously been shown to suppress excitability and synaptic transmission by upregulating potassium (K channels and downregulating nicotinic acetylcholine receptors (nAChRs in wake-promoting neurons to facilitate sleep in Drosophila. Using deletion mutagenesis, co-immunoprecipitations, ion flux assays, surface labeling and confocal microscopy, we demonstrate that only loop 2 is required for many of the previously described properties of SSS in transfected cells, including interactions with K channels and nAChRs. Collectively our data suggest that QVR/SSS, and by extension perhaps other Ly6 proteins, target effector molecules using limited protein motifs. Mapping these motifs may be useful in rational design of drugs that mimic or suppress Ly6-effector interactions to modulate nervous system function.

  17. Structural Analysis and Deletion Mutagenesis Define Regions of QUIVER/SLEEPLESS that Are Responsible for Interactions with Shaker-Type Potassium Channels and Nicotinic Acetylcholine Receptors.

    Science.gov (United States)

    Wu, Meilin; Liu, Clifford Z; Joiner, William J

    2016-01-01

    Ly6 proteins are endogenous prototoxins found in most animals. They show striking structural and functional parallels to snake α-neurotoxins, including regulation of ion channels and cholinergic signaling. However, the structural contributions of Ly6 proteins to regulation of effector molecules is poorly understood. This question is particularly relevant to the Ly6 protein QUIVER/SLEEPLESS (QVR/SSS), which has previously been shown to suppress excitability and synaptic transmission by upregulating potassium (K) channels and downregulating nicotinic acetylcholine receptors (nAChRs) in wake-promoting neurons to facilitate sleep in Drosophila. Using deletion mutagenesis, co-immunoprecipitations, ion flux assays, surface labeling and confocal microscopy, we demonstrate that only loop 2 is required for many of the previously described properties of SSS in transfected cells, including interactions with K channels and nAChRs. Collectively our data suggest that QVR/SSS, and by extension perhaps other Ly6 proteins, target effector molecules using limited protein motifs. Mapping these motifs may be useful in rational design of drugs that mimic or suppress Ly6-effector interactions to modulate nervous system function.

  18. XRCC1 Arg194Trp and Arg399Gln polymorphisms and arsenic methylation capacity are associated with urothelial carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Chien-I [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Huang, Ya-Li [Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Chen, Wei-Jen [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Shiue, Horng-Sheng [Department of Chinese Medicine, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan (China); Huang, Chao-Yuan; Pu, Yeong-Shiau [Department of Urology, National Taiwan University Hospital, College of Medicine National Taiwan University, Taipei, Taiwan (China); Lin, Ying-Chin [Department of Family Medicine, Shung Ho Hospital, Taipei Medical University, New Taipei, Taiwan (China); Department of Health Examination, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan (China); Division of Family Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan (China); Hsueh, Yu-Mei, E-mail: ymhsueh@tmu.edu.tw [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China)

    2014-09-15

    The association between DNA repair gene polymorphisms and bladder cancer has been widely studied. However, few studies have examined the correlation between urothelial carcinoma (UC) and arsenic or its metabolites. The aim of this study was to examine the association between polymorphisms of the DNA repair genes, XRCC1 Arg194Trp, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln, with urinary arsenic profiles and UC. To this end, we conducted a hospital-based case–control study with 324 UC patients and 647 age- and gender-matched non-cancer controls. Genomic DNA was used to examine the genotype of XRCC1 Arg194Trp, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln by PCR-restriction fragment length polymorphism analysis (PCR-RFLP). Urinary arsenic profiles were measured by high performance liquid chromatography (HPLC) linked with hydride generator and atomic absorption spectrometry. The XRCC1 399 Gln/Gln and 194 Arg/Trp and Trp/Trp genotypes were significantly related to UC, and the odds ratio (OR) and 95% confidence interval (95%CI) were 1.68 (1.03–2.75) and 0.66 (0.48–0.90), respectively. Participants with higher total urinary arsenic levels, a higher percentage of inorganic arsenic (InAs%) and a lower percentage of dimethylarsinic acid (DMA%) had a higher OR of UC. Participants carrying XRCC1 risk diplotypes G-C/G-C, A-C/A-C, and A-T/G-T, and who had higher total arsenic levels, higher InAs%, or lower DMA% compared to those with other XRCC1 diplotypes had a higher OR of UC. Our results suggest that the XRCC1 399 Gln/Gln and 194 Arg/Arg DNA repair genes play an important role in poor arsenic methylation capacity, thereby increasing the risk of UC in non-obvious arsenic exposure areas. - Highlights: • The XRCC1 399Gln/Gln genotype was significantly associated with increased OR of UC. • The XRCC1 194 Arg/Trp and Trp/Trp genotype had a significantly decreased OR of UC. • Combined effect of the XRCC1 genotypes and poor arsenic methylation capacity on

  19. A fungal P450 (CYP5136A3 capable of oxidizing polycyclic aromatic hydrocarbons and endocrine disrupting alkylphenols: role of Trp(129 and Leu(324.

    Directory of Open Access Journals (Sweden)

    Khajamohiddin Syed

    Full Text Available The model white rot fungus Phanerochaete chrysosporium, which is known for its versatile pollutant-biodegradation ability, possesses an extraordinarily large repertoire of P450 monooxygenases in its genome. However, the majority of these P450s have hitherto unknown function. Our initial studies using a genome-wide gene induction strategy revealed multiple P450s responsive to individual classes of xenobiotics. Here we report functional characterization of a cytochrome P450 monooxygenase, CYP5136A3 that showed common responsiveness and catalytic versatility towards endocrine-disrupting alkylphenols (APs and mutagenic/carcinogenic polycyclic aromatic hydrocarbons (PAHs. Using recombinant CYP5136A3, we demonstrated its oxidation activity towards APs with varying alkyl side-chain length (C3-C9, in addition to PAHs (3-4 ring size. AP oxidation involves hydroxylation at the terminal carbon of the alkyl side-chain (ω-oxidation. Structure-activity analysis based on a 3D model indicated a potential role of Trp(129 and Leu(324 in the oxidation mechanism of CYP5136A3. Replacing Trp(129 with Leu (W129L and Phe (W129F significantly diminished oxidation of both PAHs and APs. The W129L mutation caused greater reduction in phenanthrene oxidation (80% as compared to W129F which caused greater reduction in pyrene oxidation (88%. Almost complete loss of oxidation of C3-C8 APs (83-90% was observed for the W129L mutation as compared to W129F (28-41%. However, the two mutations showed a comparable loss (60-67% in C9-AP oxidation. Replacement of Leu(324 with Gly (L324G caused 42% and 54% decrease in oxidation activity towards phenanthrene and pyrene, respectively. This mutation also caused loss of activity towards C3-C8 APs (20-58%, and complete loss of activity toward nonylphenol (C9-AP. Collectively, the results suggest that Trp(129 and Leu(324 are critical in substrate recognition and/or regio-selective oxidation of PAHs and APs. To our knowledge, this is the first

  20. A Fungal P450 (CYP5136A3) Capable of Oxidizing Polycyclic Aromatic Hydrocarbons and Endocrine Disrupting Alkylphenols: Role of Trp129 and Leu324

    Science.gov (United States)

    Syed, Khajamohiddin; Porollo, Aleksey; Lam, Ying Wai; Yadav, Jagjit S.

    2011-01-01

    The model white rot fungus Phanerochaete chrysosporium, which is known for its versatile pollutant-biodegradation ability, possesses an extraordinarily large repertoire of P450 monooxygenases in its genome. However, the majority of these P450s have hitherto unknown function. Our initial studies using a genome-wide gene induction strategy revealed multiple P450s responsive to individual classes of xenobiotics. Here we report functional characterization of a cytochrome P450 monooxygenase, CYP5136A3 that showed common responsiveness and catalytic versatility towards endocrine-disrupting alkylphenols (APs) and mutagenic/carcinogenic polycyclic aromatic hydrocarbons (PAHs). Using recombinant CYP5136A3, we demonstrated its oxidation activity towards APs with varying alkyl side-chain length (C3-C9), in addition to PAHs (3–4 ring size). AP oxidation involves hydroxylation at the terminal carbon of the alkyl side-chain (ω-oxidation). Structure-activity analysis based on a 3D model indicated a potential role of Trp129 and Leu324 in the oxidation mechanism of CYP5136A3. Replacing Trp129 with Leu (W129L) and Phe (W129F) significantly diminished oxidation of both PAHs and APs. The W129L mutation caused greater reduction in phenanthrene oxidation (80%) as compared to W129F which caused greater reduction in pyrene oxidation (88%). Almost complete loss of oxidation of C3-C8 APs (83–90%) was observed for the W129L mutation as compared to W129F (28–41%). However, the two mutations showed a comparable loss (60–67%) in C9-AP oxidation. Replacement of Leu324 with Gly (L324G) caused 42% and 54% decrease in oxidation activity towards phenanthrene and pyrene, respectively. This mutation also caused loss of activity towards C3-C8 APs (20–58%), and complete loss of activity toward nonylphenol (C9-AP). Collectively, the results suggest that Trp129 and Leu324 are critical in substrate recognition and/or regio-selective oxidation of PAHs and APs. To our knowledge, this is the first

  1. Targeting nociceptive transient receptor potential channels to treat chronic pain: current state of the field.

    Science.gov (United States)

    Moran, Magdalene M; Szallasi, Arpad

    2017-09-19

    Control of chronic pain is frequently inadequate and/or associated with intolerable adverse effects, prompting a frantic search for new therapeutics and new therapeutic targets. Nearly two decades of preclinical and clinical research supports the involvement of transient receptor potential (TRP) channels in temperature perception, nociception and sensitization. Although there has been considerable excitement around the therapeutic potential of this channel family since the cloning and identification of TRPV1 cation channels as the capsaicin receptor more than 20 years ago, only modulators of a few channels have been tested clinically. TRPV1 channel antagonists have suffered from side effects related to the channel's role in temperature sensation; however, high dose formulations of capsaicin have reached the market and shown therapeutic utility. A number of potent, small molecule antagonists of TRPA1 channels have recently advanced into clinical trials for the treatment of inflammatory and neuropathic pain, and TRPM8 antagonists are following closely behind for cold allodynia. TRPV3, TRPV4, TRPM2 and TRPM3 channels have also been of significant interest. This review discusses the preclinical promise and status of novel analgesic agents that target TRP channels and the challenges that these compounds may face in development and clinical practice. © 2017 The British Pharmacological Society.

  2. A ligand channel through the G protein coupled receptor opsin.

    Directory of Open Access Journals (Sweden)

    Peter W Hildebrand

    Full Text Available The G protein coupled receptor rhodopsin contains a pocket within its seven-transmembrane helix (TM structure, which bears the inactivating 11-cis-retinal bound by a protonated Schiff-base to Lys296 in TM7. Light-induced 11-cis-/all-trans-isomerization leads to the Schiff-base deprotonated active Meta II intermediate. With Meta II decay, the Schiff-base bond is hydrolyzed, all-trans-retinal is released from the pocket, and the apoprotein opsin reloaded with new 11-cis-retinal. The crystal structure of opsin in its active Ops* conformation provides the basis for computational modeling of retinal release and uptake. The ligand-free 7TM bundle of opsin opens into the hydrophobic membrane layer through openings A (between TM1 and 7, and B (between TM5 and 6, respectively. Using skeleton search and molecular docking, we find a continuous channel through the protein that connects these two openings and comprises in its central part the retinal binding pocket. The channel traverses the receptor over a distance of ca. 70 A and is between 11.6 and 3.2 A wide. Both openings are lined with aromatic residues, while the central part is highly polar. Four constrictions within the channel are so narrow that they must stretch to allow passage of the retinal beta-ionone-ring. Constrictions are at openings A and B, respectively, and at Trp265 and Lys296 within the retinal pocket. The lysine enforces a 90 degrees elbow-like kink in the channel which limits retinal passage. With a favorable Lys side chain conformation, 11-cis-retinal can take the turn, whereas passage of the all-trans isomer would require more global conformational changes. We discuss possible scenarios for the uptake of 11-cis- and release of all-trans-retinal. If the uptake gate of 11-cis-retinal is assigned to opening B, all-trans is likely to leave through the same gate. The unidirectional passage proposed previously requires uptake of 11-cis-retinal through A and release of photolyzed all

  3. ACh-induced depolarization in inner ear artery is generated by activation of a TRP-like non-selective cation conductance and inactivation of a potassium conductance.

    Science.gov (United States)

    Ma, Ke-Tao; Guan, Bing-Cai; Yang, Yu-Qin; Zhao, Hui; Jiang, Zhi-Gen

    2008-05-01

    Adequate cochlear blood supply by the spiral modiolar artery (SMA) is critical for normal hearing. ACh may play a role in neuroregulation of the SMA but several key issues including its membrane action mechanisms remain poorly understood. Besides its well-known endothelium-dependent hyperpolarizing action, ACh can induce a depolarization in vascular cells. Using intracellular and whole-cell recording techniques on cells in guinea pig in vitro SMA, we studied the ionic mechanism underlying the ACh-depolarization and found that: (1) ACh induced a DAMP-sensitive depolarization when intermediate conductance KCa channels were blocked by charybdotoxin or nitrendipine. The ACh-depolarization was associated with a decrease in input resistance (R(input)) in high membrane potential (V(m)) ( approximately -40 mV) cells but with no change or an increase in R input in low Vm ( approximately -75 mV) cells. ACh-depolarization was attenuated by background membrane depolarization from approximately -70 mV in the majority of cells; (2) ACh-induced inward current in smooth muscle cells embedded in a SMA segment often showed a U-shaped I/V curve, the reversal potential of its two arms being near EK and 0 mV, respectively; (3) ACh-depolarization was reduced by low Na+, zero K+ or 20mM K+ bath solutions; (4) ACh-depolarization was inhibited by La3+ in all cells tested, by 4-AP and flufenamic acid in low Vm cells, but was not sensitive to Cd2+, Ni2+, nifedipine, niflumic acid, DIDS, IAA94, linopirdine or amiloride. We conclude that ACh-induced vascular depolarization was generated mainly by activation of a TRP-like non-selective cation channel and by inactivation of an inward rectifier K+ channel.

  4. Tryptophan scanning mutagenesis reveals distortions in the helical structure of the δM4 transmembrane domain of the Torpedo californica nicotinic acetylcholine receptor.

    Science.gov (United States)

    Caballero-Rivera, Daniel; Cruz-Nieves, Omar A; Oyola-Cintrón, Jessica; Torres-Nunez, David A; Otero-Cruz, Jose D; Lasalde-Dominicci, José A

    2012-01-01

    The lipid-protein interface is an important domain of the nicotinic acetylcholine receptor (nAChR) that has recently garnered increased relevance. Several studies have made significant advances toward determining the structure and dynamics of the lipid-exposed domains of the nAChR. However, there is still a need to gain insight into the mechanism by which lipid-protein interactions regulate the function and conformational transitions of the nAChR. In this study, we extended the tryptophan scanning mutagenesis (TrpScanM) approach to dissect secondary structure and monitor the conformational changes experienced by the δM4 transmembrane domain (TMD) of the Torpedo californica nAChR, and to identify which positions on this domain are potentially linked to the regulation of ion channel kinetics. The difference in oscillation patterns between the closed- and open-channel states suggests a substantial conformational change along this domain as a consequence of channel activation. Furthermore, TrpScanM revealed distortions along the helical structure of this TMD that are not present on current models of the nAChR. Our results show that a Thr-Pro motif at positions 462-463 markedly bends the helical structure of the TMD, consistent with the recent crystallographic structure of the GluCl Cys-loop receptor which reveals a highly bent TMD4 in each subunit. This Thr-Pro motif acts as a molecular hinge that delineates two gating blocks in the δM4 TMD. These results suggest a model in which a hinge-bending motion that tilts the helical structure is combined with a spring-like motion during transition between the closed- and open-channel states of the δM4 TMD.

  5. Calcium Release Mediated by Redox-Sensitive RyR2 Channels Has a Central Role in Hippocampal Structural Plasticity and Spatial Memory.

    Science.gov (United States)

    More, Jamileth Y; Bruna, Barbara A; Lobos, Pedro E; Galaz, José L; Figueroa, Paula L; Namias, Silvia; Sánchez, Gina L; Barrientos, Genaro C; Valdés, José L; Paula-Lima, Andrea C; Hidalgo, Cecilia; Adasme, Tatiana

    2018-03-01

    Previous studies indicate that hippocampal synaptic plasticity and spatial memory processes entail calcium release from intracellular stores mediated by ryanodine receptor (RyR) channels. In particular, RyR-mediated Ca 2+ release is central for the dendritic spine remodeling induced by brain-derived neurotrophic factor (BDNF), a neurotrophin that stimulates complex signaling pathways leading to memory-associated protein synthesis and structural plasticity. To examine if upregulation of ryanodine receptor type-2 (RyR2) channels and the spine remodeling induced by BDNF entail reactive oxygen species (ROS) generation, and to test if RyR2 downregulation affects BDNF-induced spine remodeling and spatial memory. Downregulation of RyR2 expression (short hairpin RNA [shRNA]) in primary hippocampal neurons, or inhibition of nitric oxide synthase (NOS) or NADPH oxidase, prevented agonist-mediated RyR-mediated Ca 2+ release, whereas BDNF promoted cytoplasmic ROS generation. RyR2 downregulation or inhibitors of N-methyl-d-aspartate (NMDA) receptors, or NOS or of NADPH oxidase type-2 (NOX2) prevented RyR2 upregulation and the spine remodeling induced by BDNF, as did incubation with the antioxidant agent N-acetyl l-cysteine. In addition, intrahippocampal injection of RyR2-directed antisense oligodeoxynucleotides, which caused significant RyR2 downregulation, caused conspicuous defects in a memorized spatial memory task. The present novel results emphasize the key role of redox-sensitive Ca 2+ release mediated by RyR2 channels for hippocampal structural plasticity and spatial memory. Based on these combined results, we propose (i) that BDNF-induced RyR2-mediated Ca 2+ release and ROS generation via NOS/NOX2 are strictly required for the dendritic spine remodeling and the RyR2 upregulation induced by BDNF, and (ii) that RyR2 channel expression is crucial for spatial memory processes. Antioxid. Redox Signal. 00, 000-000.

  6. The role of mesoscopic structuring on the intermixing of spin-polarised conduction channels in thin-film ferromagnets for spintronics

    Science.gov (United States)

    Alcer, D.; Atkinson, D.

    2017-09-01

    The separation of spin-up and spin-down conduction channels is fundamental to electronic transport in ferromagnets and essential for spintronic functionality. The spin states available for conduction are defined by the ferromagnetic material, but additional physical factors can affect scattering and modify the spin-dependence of conduction. Here the effect of mesoscopic structuring, arising during the growth of ferromagnetic thin films, on the electronic transport was investigated. Resistivity and anisotropic magnetoresistance were measured in a series of Ni80Fe20 thin films as a function of nominal film thickness from 3 {nm} up to 20 {nm}. The observed thickness dependence of the resisivity and magnetic anisotropy of resistivity are interpreted using a model that accounts for the macroscopic structuring from the growth of the films and incorporates a structural dependence of the spin-flip scattering. The model shows good agreement for both the thickness dependence of the resistivity and the reduction of the anisotropic magnetoresistivity. The latter indicating that increasing mixing of the conducting spin channels occurs in ultra-thin films, mainly a consequence of macroscopic structuring of the films.

  7. Effects of tryptophan starvation on levels of the trp RNA-binding attenuation protein (TRAP) and anti-TRAP regulatory protein and their influence on trp operon expression in Bacillus subtilis.

    Science.gov (United States)

    Yang, Wen-Jen; Yanofsky, Charles

    2005-03-01

    The anti-TRAP protein (AT), encoded by the rtpA gene of Bacillus subtilis, can bind to and inhibit the tryptophan-activated trp RNA-binding attenuation protein (TRAP). AT binding can prevent TRAP from promoting transcription termination in the leader region of the trp operon, thereby increasing trp operon expression. We show here that AT levels continue to increase as tryptophan starvation becomes more severe, whereas the TRAP level remains relatively constant and independent of tryptophan starvation. Assuming that the functional form of AT is a trimer, we estimate that the ratios of AT trimers per TRAP molecule are 0.39 when the cells are grown under mild tryptophan starvation conditions, 0.83 under more severe starvation conditions, and approximately 2.0 when AT is expressed maximally. As the AT level is increased, a corresponding increase is observed in the anthranilate synthase level. When AT is expressed maximally, the anthranilate synthase level is about 70% of the level observed in a strain lacking TRAP. In a nutritional shift experiment where excess phenylalanine and tyrosine could potentially starve cells of tryptophan, both the AT level and anthranilate synthase activity were observed to increase. Expression of the trp operon is clearly influenced by the level of AT.

  8. Pulse radiolysis studies of intramolecular electron transfer in model peptides and proteins. 7. Trp -> TyrO radical transformation in hen egg-white lysozyme. Effects of pH, temperature, Trp62 oxidation and inhibitor binding

    DEFF Research Database (Denmark)

    Bobrowski, K.; Holcman, J.; Poznanski, J.

    1997-01-01

    Intramolecular long-range electron transfer (LRET) in hen egg-white lysozyme (HEWL) accompanying Trp --> TyrO radical transformation was investigated in aqueous solution by pulse radiolysis as a function of pH (5.2-7.4) and temperature (283-328K). The reaction was induced by highly selective...

  9. Structure and Activity of an Aminoacyl-tRNA Synthetase that Charges tRNA with Nitro-Tryptophan

    Energy Technology Data Exchange (ETDEWEB)

    Buddha,M.; Crane, B.

    2005-01-01

    The most divergent of two tryptophanyl tRNA synthetases (TrpRS II) found in Deinococcus radiodurans interacts with a nitric oxide synthase protein that produces 4-nitro-tryptophan (4-NRP). TrpRS II efficiently charges transfer RNATrp with 4-NRP and 5-hydroxy-tryptophan (5-HRP). The crystal structures of TrpRS II bound to tryptophan and 5-HRP reveal residue substitutions that accommodate modified indoles. A class of auxiliary bacterial TrpRSs conserve this capacity to charge tRNA with nonstandard amino acids.

  10. Molecular cloning of a preprohormone from Hydra magnipapillata containing multiple copies of Hydra-L Wamide (Leu-Trp-NH2) neuropeptides: evidence for processing at Ser and Asn residues

    DEFF Research Database (Denmark)

    Leviev, I; Williamson, M; Grimmelikhuijzen, C J

    1997-01-01

    The simple, freshwater polyp Hydra is often used as a model to study development in cnidarians. Recently, a neuropeptide, cloned a preprohormone...... from Hydra magnipapillata containing 11 (eight different) immature neuropeptide sequences that are structurally related to the metamorphosis-inducing neuropeptide from sea anermones. During the final phase of our cloning experiments, another research team independently isolated and sequenced five...... most frequent one being Gly-Pro-Pro-Pro-Gly-Leu-Trp-NH2; Hydra-LWamide l; three copies). Based on their structural similarities with the metamorphosis-inducing neuropeptide from sea anemones, the mature peptides derived from the Hydra-LWamide preprohormone are potential candidates for being...

  11. Identification of flow structures in fully developed canonical and wavy channels by means of modal decomposition techniques

    Science.gov (United States)

    Ghebali, Sacha; Garicano-Mena, Jesús; Ferrer, Esteban; Valero, Eusebio

    2018-04-01

    A Dynamic Mode Decomposition (DMD) of Direct Numerical Simulations (DNS) of fully developed channel flows is undertaken in order to study the main differences in flow features between a plane-channel flow and a passively “controlled” flow wherein the mean friction was reduced relative to the baseline by modifying the geometry in order to generate a streamwise-periodic spanwise pressure gradient, as is the case for an oblique wavy wall. The present analysis reports POD and DMD modes for the plane channel, jointly with the application of a sparsity-promoting method, as well as a reconstruction of the Reynolds shear stress with the dynamic modes. Additionally, a dynamic link between the streamwise velocity fluctuations and the friction on the wall is sought by means of a composite approach both in the plane and wavy cases. One of the DMD modes associated with the wavy-wall friction exhibits a meandering motion which was hardly identifiable on the instantaneous friction fluctuations.

  12. Channelling versus inversion

    DEFF Research Database (Denmark)

    Gale, A.S.; Surlyk, Finn; Anderskouv, Kresten

    2013-01-01

    Evidence from regional stratigraphical patterns in Santonian−Campanian chalk is used to infer the presence of a very broad channel system (5 km across) with a depth of at least 50 m, running NNW−SSE across the eastern Isle of Wight; only the western part of the channel wall and fill is exposed. W......−Campanian chalks in the eastern Isle of Wight, involving penecontemporaneous tectonic inversion of the underlying basement structure, are rejected....

  13. The π Configuration of the WWW Motif of a Short Trp-Rich Peptide Is Critical for Targeting Bacterial Membranes, Disrupting Preformed Biofilms, and Killing Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Zarena, D; Mishra, Biswajit; Lushnikova, Tamara; Wang, Fangyu; Wang, Guangshun

    2017-08-08

    Tryptophan-rich peptides, being short and suitable for large-scale chemical synthesis, are attractive candidates for developing a new generation of antimicrobials to combat antibiotic-resistant bacteria (superbugs). Although there are numerous pictures of the membrane-bound structure of a single tryptophan (W), how multiple Trp amino acids assemble themselves and interact with bacterial membranes is poorly understood. This communication presents the three-dimensional structure of an eight-residue Trp-rich peptide (WWWLRKIW-NH 2 with 50% W) determined by the improved two-dimensional nuclear magnetic resonance method, which includes the measurements of 13 C and 15 N chemical shifts at natural abundance. This peptide forms the shortest two-turn helix with a distinct amphipathic feature. A unique structural arrangement is identified for the Trp triplet, WWW, that forms a π configuration with W2 as the horizontal bar and W1/W3 forming the two legs. An arginine scan reveals that the WWW motif is essential for killing methicillin-resistant Staphylococcus aureus USA300 and disrupting preformed bacterial biofilms. This unique π configuration for the WWW motif is stabilized by aromatic-aromatic interactions as evidenced by ring current shifts as well as nuclear Overhauser effects. Because the WWW motif is maintained, a change of I7 to R led to a potent antimicrobial and antibiofilm peptide with 4-fold improvement in cell selectivity. Collectively, this study elucidated the structural basis of antibiofilm activity of the peptide, identified a better peptide candidate via structure-activity relationship studies, and laid the foundation for engineering future antibiotics based on the WWW motif.

  14. Ion channeling

    International Nuclear Information System (INIS)

    Erramli, H.; Blondiaux, G.

    1994-01-01

    Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

  15. Transient receptor potential channels encode volatile chemicals sensed by rat trigeminal ganglion neurons.

    Directory of Open Access Journals (Sweden)

    Matthias Lübbert

    Full Text Available Primary sensory afferents of the dorsal root and trigeminal ganglia constantly transmit sensory information depicting the individual's physical and chemical environment to higher brain regions. Beyond the typical trigeminal stimuli (e.g. irritants, environmental stimuli comprise a plethora of volatile chemicals with olfactory components (odorants. In spite of a complete loss of their sense of smell, anosmic patients may retain the ability to roughly discriminate between different volatile compounds. While the detailed mechanisms remain elusive, sensory structures belonging to the trigeminal system seem to be responsible for this phenomenon. In order to gain a better understanding of the mechanisms underlying the activation of the trigeminal system by volatile chemicals, we investigated odorant-induced membrane potential changes in cultured rat trigeminal neurons induced by the odorants vanillin, heliotropyl acetone, helional, and geraniol. We observed the dose-dependent depolarization of trigeminal neurons upon application of these substances occurring in a stimulus-specific manner and could show that distinct neuronal populations respond to different odorants. Using specific antagonists, we found evidence that TRPA1, TRPM8, and/or TRPV1 contribute to the activation. In order to further test this hypothesis, we used recombinantly expressed rat and human variants of these channels to investigate whether they are indeed activated by the odorants tested. We additionally found that the odorants dose-dependently inhibit two-pore potassium channels TASK1 and TASK3 heterologously expressed In Xenopus laevis oocytes. We suggest that the capability of various odorants to activate different TRP channels and to inhibit potassium channels causes neuronal depolarization and activation of distinct subpopulations of trigeminal sensory neurons, forming the basis for a specific representation of volatile chemicals in the trigeminal ganglia.

  16. Identification of a mutation in the tyrosinase related protein 1 (TRP1) gene associated with brown oculocutaneous albinism (OCA3)

    Energy Technology Data Exchange (ETDEWEB)

    Wildenberg, S.C.; Oetting, W.S.; Fryer, J.P. [Univ. of Minnesota, Minneapolis, MN (United States)] [and others

    1994-09-01

    The genes responsible for the two most common types of human oculocutaneous albinism (OCA) have been identified. Mutations of the tyrosinase gene (chromosome 11q14-21) produce OCA1, and mutations of the P gene (chromosome 15q11.2-13) produce OCA2. Another type of OCA known as brown OCA or OCA3 is found commonly in the African and African-American population. OCA3 is characterized by light brown skin and hair with the ocular features of albinism and represents the third most frequent type of OCA. We previously identified dizygotic African-American twin boys who were discordant for OCA3. Melanocytes from the affected twin produced brown melanin and contained no detectable TRP1 protein. We have now characterized the TRP1 gene from the affected twin. The human TRP1 gene, homologous to the murine brown locus, contains 8 exons and maps to chromosome 9p23. Using PCR amplification of each exon coupled with SSCP analysis and direct DNA sequencing, we found the affected twin to homozygous for a single bp deletion in exon 6. The deletion removes a G in codon 368 leading to a premature stop at codon 384. We also identified a Tsp509 polymorphism in the 3{prime} UTR. We conclude that mutations of the TRP1 gene are responsible for brown OCA or OCA3, making this the third major OCA gene identified in humans.

  17. Calcium homeostasis in photoreceptor cells of Drosophila mutants inaC and trp studied with the pupil mechanism

    NARCIS (Netherlands)

    Hofstee, CA; Stavenga, DG

    1996-01-01

    The light-driven pupil mechanism, consisting of an assembly of mobile pigment granules inside the photoreceptor cells, has been investigated by in vivo reflection microspectrophotometry in wild type (WT) Drosophila and in the photoreceptor mutants inaC and trp. The pupillary response of a

  18. TRP receptory jako transdukční molekuly nociceptivních podnětů

    Czech Academy of Sciences Publication Activity Database

    Boukalová, Štěpánka; Vlachová, Viktorie

    2008-01-01

    Roč. 11, č. 4 (2008), s. 194-206 ISSN 1212-0634 R&D Projects: GA MŠk(CZ) 1M0517; GA MŠk(CZ) LC554; GA ČR(CZ) GA305/06/0319 Institutional research plan: CEZ:AV0Z50110509 Keywords : termo-TRP receptory * nociceptory Subject RIV: ED - Physiology

  19. Channel flow and localized fault bounded slice tectonics (LFBST): Insights from petrological, structural, geochronological and geospeedometric studies in the Sikkim Himalaya, NE India

    Science.gov (United States)

    Chakraborty, Sumit; Mukhopadhyay, Dilip K.; Chowdhury, Priyadarshi; Rubatto, Daniela; Anczkiewicz, Robert; Trepmann, Claudia; Gaidies, Fred; Sorcar, Nilanjana; Dasgupta, Somnath

    2017-06-01

    One of the enduring debates in the study of the Himalayan orogen (and continental collision zones in general) is whether the salient observed features are explained (a) by localized deformation along discrete, narrow fault zones/ductile shear zones separating individual blocks or slices (e.g. critical taper or wedge tectonic models), or (b) by distributed deformation dominated by wide zones of visco-plastic flow in the solid or a partially molten state (e.g. channel flow models). A balanced cross-section from Sikkim in the eastern Himalaya that is based on structural data and is drawn to satisfy petrological and geophysical constraints as well, is used in combination with information from petrology, geochronology, geospeedometry and microstructural data to address this question. We discuss that any tectonic model needs to be thermally, rheologically, geometrically and temporally viable in order to qualify as a suitable description of a system; models such as channel flow and critical taper are considered in this context. It is shown that channel flow models may operate with or without an erosional porthole (channel with tunnel and funnel mode vs. channels with only the tunnel mode) and that the predicted features differ significantly between the two. Subsequently, we consider a large body of data from Sikkim to show that a channel flow type model (in the tunneling without funneling mode), such as the ones of Faccenda et al. (2008), describes features formed at high temperatures very well, while features formed at lower temperatures are more consistent with the operation of localized, fault-bounded, slice tectonics, (LFBST, be it in the form of critical taper, wedge tectonics, or something else). Thus, the two modes are not competing, but collaborating, processes and both affect a given rock unit at different points of time during burial, metamorphism and exhumation. A transitional stage separates the two end-member styles of tectonic evolution. The proposed models

  20. Benchmarking the stability of human detergent-solubilised voltage-gated sodium channels for structural studies using eel as a reference

    Science.gov (United States)

    Slowik, Daria; Henderson, Richard

    2015-01-01

    With the ultimate goal of detailed structural analysis of mammalian and particularly human voltage-gated sodium channels (VGSCs), we have investigated the relative stability of human and rat VGSCs and compared them with electric eel VGSC. We found that NaV1.3 from rat was the most stable after detergent solubilisation. The order of stability was rNaV1.3 > hNaV1.2 > hNaV1.1 > hNaV1.6 > hNaV1.3 > hNaV1.4. However, a comparison with the VGSC from Electrophorus electricus, which is most similar to NaV1.4, shows that the eel VGSC is considerably more stable in detergent than the human VGSCs examined. We conclude that current methods of structural analysis, such as single particle electron cryomicroscopy (cryoEM), may be most usefully targeted to eel VGSC or rNaV1.3, but that structural analysis on the full spectrum of VGSCs, by methods that require greater stability such as crystallisation and X-ray crystallography, will require further stabilisation of the channel. PMID:25838126

  1. Biphasic DC measurement approach for enhanced measurement stability and multi-channel sampling of self-sensing multi-functional structural materials doped with carbon-based additives

    Science.gov (United States)

    Downey, Austin; D'Alessandro, Antonella; Ubertini, Filippo; Laflamme, Simon; Geiger, Randall

    2017-06-01

    Investigation of multi-functional carbon-based self-sensing structural materials for structural health monitoring applications is a topic of growing interest. These materials are self-sensing in the sense that they can provide measurable electrical outputs corresponding to physical changes such as strain or induced damage. Nevertheless, the development of an appropriate measurement technique for such materials is yet to be achieved, as many results in the literature suggest that these materials exhibit a drift in their output when measured with direct current (DC) methods. In most of the cases, the electrical output is a resistance and the reported drift is an increase in resistance from the time the measurement starts due to material polarization. Alternating current methods seem more appropriate at eliminating the time drift. However, published results show they are not immune to drift. Moreover, the use of multiple impedance measurement devices (LCR meters) does not allow for the simultaneous multi-channel sampling of multi-sectioned self-sensing materials due to signal crosstalk. The capability to simultaneously monitor multiple sections of self-sensing structural materials is needed to deploy these multi-functional materials for structural health monitoring. Here, a biphasic DC measurement approach with a periodic measure/discharge cycle in the form of a square wave sensing current is used to provide consistent, stable resistance measurements for self-sensing structural materials. DC measurements are made during the measurement region of the square wave while material depolarization is obtained during the discharge region of the periodic signal. The proposed technique is experimentally shown to remove the signal drift in a carbon-based self-sensing cementitious material while providing simultaneous multi-channel measurements of a multi-sectioned self-sensing material. The application of the proposed electrical measurement technique appears promising for real

  2. An NMR investigation of the structure, function and role of the hERG channel selectivity filter in the long QT syndrome.

    Science.gov (United States)

    Gravel, Andrée E; Arnold, Alexandre A; Dufourc, Erick J; Marcotte, Isabelle

    2013-06-01

    The human ether-a-go-go-related gene (hERG) voltage-gated K(+) channels are located in heart cell membranes and hold a unique selectivity filter (SF) amino acid sequence (SVGFG) as compared to other K(+) channels (TVGYG). The hERG provokes the acquired long QT syndrome (ALQTS) when blocked, as a side effect of drugs, leading to arrhythmia or heart failure. Its pore domain - including the SF - is believed to be a cardiotoxic drug target. In this study combining solution and solid-state NMR experiments we examine the structure and function of hERG's L(622)-K(638) segment which comprises the SF, as well as its role in the ALQTS using reported active drugs. We first show that the SF segment is unstructured in solution with and without K(+) ions in its surroundings, consistent with the expected flexibility required for the change between the different channel conductive states predicted by computational studies. We also show that the SF segment has the potential to perturb the membrane, but that the presence of K(+) ions cancels this interaction. The SF moiety appears to be a possible target for promethazine in the ALQTS mechanism, but not as much for bepridil, cetirizine, diphenhydramine and fluvoxamine. The membrane affinity of the SF is also affected by the presence of drugs which also perturb model DMPC-based membranes. These results thus suggest that the membrane could play a role in the ALQTS by promoting the access to transmembrane or intracellular targets on the hERG channel, or perturbing the lipid-protein synergy. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. TrpA1 Regulates Defecation of Food-Borne Pathogens under the Control of the Duox Pathway.

    Directory of Open Access Journals (Sweden)

    Eun Jo Du

    2016-01-01

    Full Text Available Pathogen expulsion from the gut is an important defense strategy against infection, but little is known about how interaction between the intestinal microbiome and host immunity modulates defecation. In Drosophila melanogaster, dual oxidase (Duox kills pathogenic microbes by generating the microbicidal reactive oxygen species (ROS, hypochlorous acid (HOCl in response to bacterially excreted uracil. The physiological function of enzymatically generated HOCl in the gut is, however, unknown aside from its anti-microbial activity. Drosophila TRPA1 is an evolutionarily conserved receptor for reactive chemicals like HOCl, but a role for this molecule in mediating responses to gut microbial content has not been described. Here we identify a molecular mechanism through which bacteria-produced uracil facilitates pathogen-clearing defecation. Ingestion of uracil increases defecation frequency, requiring the Duox pathway and TrpA1. The TrpA1(A transcript spliced with exon10b (TrpA1(A10b that is present in a subset of midgut enteroendocrine cells (EECs is critical for uracil-dependent defecation. TRPA1(A10b heterologously expressed in Xenopus oocytes is an excellent HOCl receptor characterized with elevated sensitivity and fast activation kinetics of macroscopic HOCl-evoked currents compared to those of the alternative TRPA1(A10a isoform. Consistent with TrpA1's role in defecation, uracil-excreting Erwinia carotovora showed higher persistence in TrpA1-deficient guts. Taken together, our results propose that the uracil/Duox pathway promotes bacteria expulsion from the gut through the HOCl-sensitive receptor, TRPA1(A10b, thereby minimizing the chances that bacteria adapt to survive host defense systems.

  4. Structure and dynamics of the biota associated with Macrocystis pyrifera (Phaeophyta from the Beagle Channel, Tierra del Fuego

    Directory of Open Access Journals (Sweden)

    Mariana L. Adami

    1999-12-01

    Full Text Available The community associated to the kelp Macrocystis pyrifera from the Beagle Channel (54°00´S; 68°20´W was studied. Sixty-eight taxa including Algae (5, Porifera (indet., Bryozoa (7, Nemertea (2, Annelida (10, Mollusca (22, Crustacea (15 and Echinodermata (7 were recognized. A seasonal sampling during one year showed differences in taxa composition when comparing (a two different environments; (b the spring-summer period and the autumn-winter period; and (c the parts of the alga (fronds and holdfast.

  5. Structural Dynamics of Soluble Chloride Intracellular Channel Protein CLIC1 Examined by Amide Hydrogen-Deuterium Exchange Mass Spectrometry (DXMS)†

    Science.gov (United States)

    Stoychev, Stoyan H.; Nathaniel, Christos; Fanucchi, Sylvia; Brock, Melissa; Li, Sheng; Asmus, Kyle; Woods, Virgil L.; Dirr, Heini W.

    2009-01-01

    Chloride intracellular channel protein 1 (CLIC1) functions as an anion channel in plasma and nuclear membranes when its soluble monomeric form converts to an integral-membrane form. The transmembrane region of CLIC1 is located in its thioredoxin-like domain 1 but the mechanism whereby the protein converts to its membrane conformation has yet to be determined. Since channel formation in membranes is enhanced at low pH (5 to 5.5), a condition that is found at the surface of membranes, the structural dynamics of soluble CLIC1 was studied at pH 7 and at pH 5.5 in the absence of membranes by amide hydrogen-deuterium exchange mass spectrometry (DXMS). Rapid hydrogen exchange data indicate that CLIC1 displays a similar core structure at these pH values. Domain 1 is less stable than the all-helical domain 2 and, while the structure of domain 1 remains intact, its conformational flexibility is further increased in an acidic environment (pH 5.5). In the absence of membrane, an acidic environment appears to prime the solution structure of CLIC1 by destabilising domain 1 in order to lower the activation energy barrier for its conversion to the membrane-insertion conformation. The significantly enhanced H/D-exchange rates at pH 5.5 displayed by two segments (peptides 11-31 and 68-82) could be due to the protonation of acidic residues in salt bridges. One of these segments (peptide 11-31) includes part of the transmembrane region which, in the solution structure, consists of helix α1. This helix is intrinsically stable and is most likely retained in the membrane conformation. Strand β2, another element of the transmembrane region, displays a propensity to form a helical structure and has putative N- and C-capping motifs, suggesting that it too most likely forms a helix in a lipid bilayer. PMID:19650640

  6. Purification and subunit structure of a putative K sup + -channel protein identified by its binding properties for dendrotoxin I

    Energy Technology Data Exchange (ETDEWEB)

    Rehm, H.; Lazdunski, M. (Centre National de la Recherche Scientifique, Nice (France))

    1988-07-01

    The binding protein for the K{sup +}-channel toxin dendrotoxin I was purified from a detergent extract of rat brain membranes. The purification procedure utilized chromatography on DEAE-Trisacryl, affinity chromatography on a dendrotoxin-I-Aca 22 column, and wheat germ agglutinin-Affigel 10 with a final 3,800- to 4,600-fold enrichment and a recovery of 8-16%. The high affinity (K{sub d}, 40-100 pM) and specificity of the binding site are retained throughout the purification procedure. Analysis of the purified material on silver-stained NaDodSO{sub 4}/polyacrylamide gel revealed three bands of M{sub r} 76,000-80,000, 38,000 and 35,000. Interestingly, the binding site for {sup 125}I-labeled mast cell degranulating peptide, another putative K{sup +}-channel ligand from bee venom, which induces long-term potentiation in hippocampus, seems to reside on the same protein complex, as both binding sites copurify through the entire purification protocol.

  7. Purification and subunit structure of a putative K+-channel protein identified by its binding properties for dendrotoxin I

    International Nuclear Information System (INIS)

    Rehm, H.; Lazdunski, M.

    1988-01-01

    The binding protein for the K + -channel toxin dendrotoxin I was purified from a detergent extract of rat brain membranes. The purification procedure utilized chromatography on DEAE-Trisacryl, affinity chromatography on a dendrotoxin-I-Aca 22 column, and wheat germ agglutinin-Affigel 10 with a final 3,800- to 4,600-fold enrichment and a recovery of 8-16%. The high affinity (K d , 40-100 pM) and specificity of the binding site are retained throughout the purification procedure. Analysis of the purified material on silver-stained NaDodSO 4 /polyacrylamide gel revealed three bands of M r 76,000-80,000, 38,000 and 35,000. Interestingly, the binding site for 125 I-labeled mast cell degranulating peptide, another putative K + -channel ligand from bee venom, which induces long-term potentiation in hippocampus, seems to reside on the same protein complex, as both binding sites copurify through the entire purification protocol

  8. Volume Regulated Channels

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjær

    , controlled cell death and cellular migration. Volume regulatory mechanisms has long been in focus for regulating cellular proliferation and my thesis work have been focusing on the role of Cl- channels in proliferation with specific emphasis on ICl, swell. Pharmacological blockage of the ubiquitously...... but are also essential for a number of physiological processes such as proliferation, controlled cell death, migration and endocrinology. The thesis have been focusing on two Channels, namely the swelling activated Cl- channel (ICl, swell) and the transient receptor potential Vanilloid (TRPV4) channel. I: Cl...... understood. Potential agonist binding sites have been proposed in transmembrane domains 3 and 4, in congruence with agonist binding sites of TRPV1. However, the functional relationship between TRPV4 and agonist binding is not yet understood. In this thesis is further elaborate the structure...

  9. Sensing with Ion Channels

    CERN Document Server

    Martinac, Boris

    2008-01-01

    All living cells are able to detect and translate environmental stimuli into biologically meaningful signals. Sensations of touch, hearing, sight, taste, smell or pain are essential to the survival of all living organisms. The importance of sensory input for the existence of life thus justifies the effort made to understand its molecular origins. Sensing with Ion Channels focuses on ion channels as key molecules enabling biological systems to sense and process the physical and chemical stimuli that act upon cells in their living environment. Its aim is to serve as a reference to ion channel specialists and as a source of new information to non specialists who want to learn about the structural and functional diversity of ion channels and their role in sensory physiology.

  10. Geochemical and geo-electrical study of mud pools at the Mutnovsky volcano (South Kamchatka, Russia): Behavior of elements, structures of feeding channels and a model of origin

    International Nuclear Information System (INIS)

    Bessonova, E.P.; Bortnikova, S.B.; Gora, M.P.; Manstein, Yu.A.; Shevko, A.Ya.; Panin, G.L.; Manstein, A.K.

    2012-01-01

    This study presents data on the geochemical composition of boiling mud pools at the Mutnovsky volcano. The physicochemical characteristics of the pools and the concentrations of major, minor and trace elements in pool solutions vary widely. A comparison of the geochemical compositions of host rocks and solutions indicates that leaching from rocks is not the only source of chemicals in thermal solutions. Geophysical studies reveal the inner structure of thermal fields, which reflect the shapes of the underground reservoirs and feed channels. Using geophysical methods (electrical resistivity tomography and frequency domain investigations), it was shown that the vertical structure and complex geochemical zonation of the feed channels leads to a high contrast in the compositions of the mud solutions. These findings answer questions about the origin and composition of surface manifestations. To elucidate the mechanisms of solution formation, an attempt was made to describe the magmatic fluid evolution and the resulting mixing of waters by physical and mathematical models. The model illustrates fluid migration from a magma chamber to the surface. It is shown that the formation of brines corresponding to the mud pool composition is possible during secondary boiling.

  11. Structural and Thermoelectric Properties of Bi85Sb15 Prepared by Non-equal Channel Angular Extrusion

    Science.gov (United States)

    El-Asfoury, Mohamed S.; Nasr, Mohamed N. A.; Nakamura, Koichi; Abdel-Moneim, Ahmed

    2018-01-01

    We report on the mechanical and transport properties of polycrystalline bulk Bi85Sb15, as a low-temperature thermoelectric material. Bi85Sb15 samples were prepared by mechanical alloying and hot isostatic pressing, followed by sever plastic deformation (SPD). SPD was applied by either equal channel angular extrusion (ECAE) or non-equal channel angular extrusion (NECAE), at two different temperatures (373 K and 423 K). X-ray diffraction and scanning electron microscopy were used to characterize the prepared samples. The transport properties including the electrical conductivity, Seebeck coefficient and thermal conductivity were investigated, and correlated with the microstructure over the temperature range of 160-360 K. NECAE was found to be more effective than ECAE in enhancing bulk density, grain refinement and preferential grain orientation along the extrusion direction, particularly at higher processing temperatures. This is attributed to the better grain alignment and the creation of more intense grain boundaries and dislocation density, which resulted in an enhancement in carrier mobility and phonon scattering and hence a higher Z value. The highest Z value was achieved via NECAE at 423 K, and had a value of 0.39 × 10-3 K-1 at 250 K, which is 55% higher than that of the hot-pressed sample, 0.22 × 10-3 K-1 at 270 K. Also, the micro-hardness of the hot-pressed sample increases by at least 20% by SPD processes. Accordingly, optimized SPD can be classified as an effective processing tool for feasible mass production of bulk Bi85Sb15 alloy with better thermoelectric performance.

  12. Organization of the rabbit vitreous body : Lamellae, Cloquet's channel and a novel structure, the 'alae canalis Cloqueti'

    NARCIS (Netherlands)

    Los, LI; van Luyn, MJA; Nieuwenhuis, P

    Even though the rabbit is a frequently used animal model for studies on Vitreous function and pathobiology, data on the structural organization of the rabbit Vitreous are scarce. The aim of the present study is to give a detailed description of rabbit vitreous structure in order to provide a basis

  13. Chromosome 11 loss from thymic lymphomas induced in heterozygous Trp53 mice by phenolphthalein.

    Science.gov (United States)

    Hulla, J E; French, J E; Dunnick, J K

    2001-04-01

    C57BL/6 p53 (+/-) N5 mice heterozygous for a null p53 allele were given phenolphthalein to learn more about mechanisms of carcinogenesis and to evaluate the p53-deficient mouse as a tool for identifying potential human carcinogens. DNA samples isolated from 10 phenolphthalein-induced thymic lymphomas were analyzed for loss of heterozygosity (LOH) at the Trp53 locus and simple sequence length polymorphic (SSLP) loci. The initial screening revealed remarkable results from only chromosome 11. Allelotyping at approximately five centiMorgan intervals, we found SSLP heterozygosity for C57BL/6 and 129Sv over much of chromosome 11. In the tumors, treatment-related LOH was apparent on chromosome 11 at each of the 28 informative loci examined. The strain-specific polymorphism lost from individual tumors allowed us to deduce the distribution of alleles along the length of the maternal and paternal chromosomes 11. The allelic patterns indicate that mitotic homologous recombination occurred during embryogenesis if breeding protocols were carried out as described. The mitotic recombination observed may be attributable to p53 haploinsufficiency for normal suppression of mitotic recombination.

  14. Possible involvement of transient receptor potential channels in electrophile-induced insulin secretion from RINm5F cells.

    Science.gov (United States)

    Numazawa, Satoshi; Takase, Makiko; Ahiko, Tomomi; Ishii, Masakazu; Shimizu, Shun-ichi; Yoshida, Takemi

    2012-01-01

    Endogenously produced reactive oxygen species reportedly stimulate insulin secretion from islet β-cells. However, the molecular machinery that governs the oxidant-induced insulin secretion has yet to be determined. The present study demonstrates, using rat islet β-cell-derived RINm5F cells, the involvement of the transient receptor potential (TRP) cation channels in the insulin secretion induced by the lipid peroxidation product 4-hydroxy-2-nonenal. Short-term (1 h) exposure of 4-hydroxy-2-nonenal induced a transient increase in intracellular Ca(2+) concentration and subsequent insulin secretion in a concentration-dependent manner. The increase in intracellular Ca(2+) concentration seemed to be due to an influx through the L-type voltage-dependent Ca(2+) channel, since it was not observed when extracellular Ca(2+) was absent and was inhibited almost completely by diltiazem or nifedipine. Ruthenium red, a non-specific inhibitor of TRP channels, inhibited the Ca(2+) influx and insulin secretion evoked by 4-hydroxy-2-nonenal. Among the TRP channels, TRPA1 was found to be predominantly expressed, not only in RINm5F cells, but also rat islets. TRPA1 agonists, allylisothiocyanate and 15-deoxy-Δ(12,14)-prostaglandin J(2), significantly induced Ca(2+) influx, and a specific inhibitor TRPA1, HC-030031, blocked the effects elicited by 4-hydroxy-2-nonenal. These results suggest that 4-hydroxy-2-nonenal induces Ca(2+) influx via the activation of TRP channels, including TRPA1, which appears to be coupled with the L-type voltage-dependent Ca(2+) channel, and ultimately insulin secretion in RINm5F cells.

  15. The Bolivar Channel Ecosystem of the Galapagos Marine Reserve: Energy flow structure and role of keystone groups

    Science.gov (United States)

    Ruiz, Diego J.; Wolff, Matthias

    2011-08-01

    The Bolivar Channel Ecosystem (BCE) is among the most productive zones in the Galapagos Marine Reserve (GMR). It is exposed to relatively cool, nutrient-rich waters of the Cromwell current, which are brought to the photic zone through topographic upwelling. The BCE is characterized by a heterogeneous rocky reef habitat covered by dense algae beds and inhabited by numerous invertebrate and fish species, which represent the food for higher predators including seals and sharks and exploited fish species. In addition, plankton and detritus based food chains channel large amounts of energy through the complex food web. Important emblematic species of the Galapagos archipelagos reside in this area such as the flightless cormorant, the Galapagos penguin and the marine iguanas. A trophic model of BCE was constructed for the habitats < 30 m depth that fringe the west coast of Isabela and east coast of Fernandina islands covering 14% of the total BCE area (44 km 2). The model integrates data sets from sub tidal ecological monitoring and marine vertebrate population monitoring (2004 to 2008) programs of the Charles Darwin Foundation and consists of 30 compartments, which are trophically linked through a diet matrix. Results reveal that the BCE is a large system in terms of flows (38 695 t km - 2 yr - 1 ) comparable to Peruvian Bay Systems of the Humboldt upwelling system. A very large proportion of energy flows from the primary producers (phytoplankton and macro-algae) to the second level and to the detritus pool. Catches are high (54.3 t km - 2 yr - 1 ) and are mainly derived from the second and third trophic levels (mean TL of catch = 2.45) making the fisheries gross efficiency high (0.3%). The system's degree of development seems rather low as indicated by a P/R ratio of 4.19, a low ascendency (37.4%) and a very low Finn's cycling index (1.29%). This is explained by the system's exposure to irregular changes in oceanographic conditions as related to the EL Niño Southern

  16. Structures of the PutA peripheral membrane flavoenzyme reveal a dynamic substrate-channeling tunnel and the quinone-binding site.

    Science.gov (United States)

    Singh, Harkewal; Arentson, Benjamin W; Becker, Donald F; Tanner, John J

    2014-03-04

    Proline utilization A (PutA) proteins are bifunctional peripheral membrane flavoenzymes that catalyze the oxidation of L-proline to L-glutamate by the sequential activities of proline dehydrogenase and aldehyde dehydrogenase domains. Located at the inner membrane of Gram-negative bacteria, PutAs play a major role in energy metabolism by coupling the oxidation of proline imported from the environment to the reduction of membrane-associated quinones. Here, we report seven crystal structures of the 1,004-residue PutA from Geobacter sulfurreducens, along with determination of the protein oligomeric state by small-angle X-ray scattering and kinetic characterization of substrate channeling and quinone reduction. The structures reveal an elaborate and dynamic tunnel system featuring a 75-Å-long tunnel that links the two active sites and six smaller tunnels that connect the main tunnel to the bulk medium. The locations of these tunnels and their responses to ligand binding and flavin reduction suggest hypotheses about how proline, water, and quinones enter the tunnel system and where L-glutamate exits. Kinetic measurements show that glutamate production from proline occurs without a lag phase, consistent with substrate channeling and implying that the observed tunnel is functionally relevant. Furthermore, the structure of reduced PutA complexed with menadione bisulfite reveals the elusive quinone-binding site. The benzoquinone binds within 4.0 Å of the flavin si face, consistent with direct electron transfer. The location of the quinone site implies that the concave surface of the PutA dimer approaches the membrane. Altogether, these results provide insight into how PutAs couple proline oxidation to quinone reduction.

  17. Ingestion of transient receptor potential channel agonists attenuates exercise-induced muscle cramps.

    Science.gov (United States)

    Craighead, Daniel H; Shank, Sean W; Gottschall, Jinger S; Passe, Dennis H; Murray, Bob; Alexander, Lacy M; Kenney, W Larry

    2017-09-01

    Exercise-associated muscle cramping (EAMC) is a poorly understood problem that is neuromuscular in origin. Ingestion of transient receptor potential (TRP) channel agonists has been efficacious in attenuating electrically induced muscle cramps. This study examines the effect of TRP agonist ingestion on voluntarily induced EAMC and motor function. Study 1: Thirty-nine participants completed 2 trials after ingesting TRP agonist-containing active treatment (A), or vehicle (V) control. Cramping in the triceps surae muscle was induced via voluntary isometric contraction. Study 2: After ingesting A or V, 31 participants performed kinematic and psychomotor tests of manual dexterity. A increased precramp contraction duration (A, 36.9 ± 4.1 s; V, 27.8 ± 3.1 s), decreased cramp EMG area under the curve (A, 37.3 ± 7.7 %EMG max ·s; V, 77.2 ± 17.7 %EMG max ·s), increased contraction force to produce the cramp (A, 13.8 ± 1.8 kg; V, 9.9 ± 1.6 kg), and decreased postcramp soreness (A, 4.1 ± 0.3 arbitrary units (a.u.); V, 4.7 ± 0.3 a.u.). Kinematic and psychomotor tests were not affected. TRP agonist ingestion attenuated EAMC characteristics without affecting motor function. Muscle Nerve 56: 379-385, 2017. © 2017 Wiley Periodicals, Inc.

  18. The Shallow Subsurface Geological Structures at the Chang'E-3 Landing Site Based on Lunar Penetrating Radar Channel-2B Data

    Science.gov (United States)

    Zhao, N.; Zhu, P.; Yuan, Y.; Yang, K.; Xiao, L.; Xiao, Z.

    2014-12-01

    The Lunar Penetrating Radar (LPR) carried by the Yutu rover of the Chinese Chang'E-3 mission has detected the shallow subsurface structures for the landing site at the northern Mare Imbrium. The antenna B of the LPR Channel-2 has collected more than 2000 traces of usable raw data. We performed calibration on the LPR data including amplitude compensation, filtering, and deconvolution. The processed results reveal that the shallow subsurface of the landing site can be divided into three major layers whose thicknesses are ~1, ~3, and 2-7 m, respectively. Variations occur on the thickness of each layer at different locations. Considering the geological background of the landing site, we interpret that the first layer is the regolith layer accumulated over ~80 Ma since the formation of the 450 m diameter Chang'E A crater. This regolith layer was formed on the basis of the ejecta deposits of Chang'E A. The second layer is the remnant continuous ejecta deposits from the Chang'E A crater, which is thicker closer to the crater rim and thinning outwardly. The Chang'E A crater formed on a paleo-regolith layer over the Eratosthenian basalts, which represents the third layer detected by the Channel 2B of the LPR.

  19. Investigation of 2D photonic crystal structure based channel drop filter using quad shaped photonic crystal ring resonator for CWDM system

    Energy Technology Data Exchange (ETDEWEB)

    Chhipa, Mayur Kumar, E-mail: mayurchhipa1@gmail.com; Dusad, Lalit Kumar [Government Engineering College Ajmer, Rajasthan (India); Rajasthan Technical University, Kota, Rajasthan (India)

    2016-05-06

    In this paper, the design & performance of two dimensional (2-D) photonic crystal structure based channel drop filter is investigated using quad shaped photonic crystal ring resonator. In this paper, Photonic Crystal (PhC) based on square lattice periodic arrays of Gallium Indium Phosphide (GaInP) rods in air structure have been investigated using Finite Difference Time Domain (FDTD) method and photonic band gap is being calculated using Plane Wave Expansion (PWE) method. The PhC designs have been optimized for telecommunication wavelength λ= 1571 nm by varying the rods lattice constant. The number of rods in Z and X directions is 21 and 20, with lattice constant 0.540 nm it illustrates that the arrangement of Gallium Indium Phosphide (GaInP) rods in the structure which gives the overall size of the device around 11.4 µm × 10.8 µm. The designed filter gives good dropping efficiency using 3.298, refractive index. The designed structure is useful for CWDM systems. This device may serve as a key component in photonic integrated circuits. The device is ultra compact with the overall size around 123 µm{sup 2}.

  20. Análisis preliminar de la estructura primaria y secundaria del ARNtTrp en tortugas marinas

    Directory of Open Access Journals (Sweden)

    Harvey Infante-Rojas

    2015-06-01

    Full Text Available Actualmente existen siete especies de tortugas marinas, todas amenazadas o en riesgo inminente de extinción. Los estudios con ADN mitocondrial han permitido hacer acercamientos sobre filogenia, evolución, rutas migratorias y centros de dispersión, además para la identificación de polimorfismos y haplotipos, siendo base para planes de manejo y conservación. El presente estudio representa la primera descripción comparada de la estructura primaria y secundaria del ARNtTrp mitocondrial en tortugas marinas. Se realizó un alineamiento múltiple de 26 secuencias del gen que codifica para el ARNtTrp y se propuso la estructura secundaria utilizando el programa ARWEN. Se identificaron potenciales interacciones terciarias por homología comparada con el ARNtTrp de mamíferos. Los resultados mostraron una secuencia consenso de 76 bases con siete regiones conservadas que representan el 76 % de la molécula. Se identificaron polimorfismos que representan tres haplotipos para C. caretta, dos para C. mydas y uno para cada una de las demás especies. Las estructuras secundarias mostraron cambios nucleotídicos puntuales para cada especie y también mostraron que el tallo aceptor, el brazo TψC y el bucle anticodón son motivos conservados en el ARNtTrp de las tortugas marinas. Se encontró un enlace no canónico tipo A-A en el tallo DHU que podría considerarse característico de tortugas marinas. Además, se obtuvo una estructura secundaria consenso en donde se identificaron las siete regiones conservadas, seis posibles interacciones terciarias y el bucle DHU como región variable.

  1. Loss of dispersion energy changes the stability and folding/unfolding equilibrium of the Trp-Cage protein

    Czech Academy of Sciences Publication Activity Database

    Černý, Jiří; Vondrášek, Jiří; Hobza, Pavel

    2009-01-01

    Roč. 113, č. 16 (2009), s. 5657-5660 ISSN 1520-6106 R&D Projects: GA MŠk LC512; GA ČR GA203/06/1727 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50520701 Keywords : Trp-Cage protein * dispersion energy * protein folding Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.471, year: 2009

  2. MARKETING CHANNELS

    Directory of Open Access Journals (Sweden)

    Ljiljana Stošić Mihajlović

    2014-07-01

    Full Text Available Marketing channel is a set of entities and institutions, completion of distribution and marketing activities, attend the efficient and effective networking of producers and consumers. Marketing channels include the total flows of goods, money and information taking place between the institutions in the system of marketing, establishing a connection between them. The functions of the exchange, the physical supply and service activities, inherent in the system of marketing and trade. They represent paths which products and services are moving after the production, which will ultimately end up buying and eating by the user.

  3. Relation of Trp64Arg polymorphism of beta 3 adrenoreceptor gene with metabolic syndrome and insulin resistance in obese women.

    Science.gov (United States)

    De Luis Román, Daniel Antonio; Primo, David; Izaola, Olatz; Aller, Rocío

    2017-03-30

    Trp64Arg variant in beta 3 adrenoreceptor has been reported to be associated with increased body weight and insulin resistance. These risk factors are the ones that make up the so-called metabolic syndrome. The aim of our study was to investigate the relationship between metabolic syndrome and Trp64Arg polymorphism in the beta3 adrenoreceptor gene in obese women. A population of 531 obese women was analyzed in cross-sectional survey. A bioimpedance, blood pressure, a serial assessment of nutritional intake with 3 days written food records and biochemical analysis were performed. Genotype of beta 3 adrenoreceptor gene polymorphism (Trp64Arg) was studied. Prevalence of metabolic syndrome (MS) with ATP III definition was 47.1% (250 patients) and 52.9% patients without MS (n = 281 patients). Prevalence of beta 3 genotypes was similar in patients with metabolic syndrome (87.6% wild genotype and 12.4% mutant genotype) and without metabolic syndrome (87.9% wild genotype and 12.1% mutant genotype). Insulin and HOMA levels were higher in patients with mutant genotype than wild type, in patients with and without metabolic syndrome. In mutant group of beta3 adrenoreceptor gene patients have higher insulin and HOMA levels than wild type group, without relation with metabolic syndrome.

  4. The tryptophan synthetase gene TRP1 of Nodulisporium sp.: molecular characterization and its relation to nodulisporic acid A production.

    Science.gov (United States)

    Ireland, C; Peekhaus, N; Lu, P; Sangari, R; Zhang, A; Masurekar, P; An, Z

    2008-06-01

    Nodulisporic acid A (NAA), an insecticidal indole diterpene, is produced by the fungus Nodulisporium sp. Since indole-3-glycerolphosphate is the precursor of the indole moiety of NAA, it is suggested that the activity of tryptophan synthetase may play a role in NAA biosynthesis. To investigate this hypothesis, the tryptophan synthetase gene TRP1 of Nodulisporium sp. was cloned and characterized. The gene consists of three introns of 146, 68, and 57 bp. The four exons encode a protein of 712 amino acids, the sequence of which is highly homologous to that of other fungal tryptophan synthetase proteins. The transcription initiation site was mapped 66 bp upstream to the ATG, and the polyA tail attachment site is 169 bp downstream to the translation stop codon. Replacement of the N-terminal half of the gene with a hygromycin selection marker yielded mutants with the tryptophan auxotroph/hygromycin-resistance (trp(-)/hyr) phenotype. The TRP1 mutants required a high concentration of tryptophan supplement in solid medium (10 mM) to sustain minimal growth and failed to produce NAA in the production medium (FFL-CAM) supplemented with high concentrations of tryptophan.

  5. Effect of Val 73 --> Trp mutation on the reaction of "cambialistic" superoxide dismutase from Propionibacterium shermanii with hydrogen peroxide.

    Science.gov (United States)

    Gabbianelli, R; Battistoni, A; Capo, C; Polticelli, F; Rotilio, G; Meier, B; Desideri, A

    1997-09-01

    The H2O2 inactivation of the "cambialistic" superoxide dismutases from Propionibacterium shermanii, which is active with either iron or manganese at the active site, has been studied in the native and Val 73 --> Trp mutant enzymes. The wild-type iron-containing form of this enzyme is much more resistant to treatment with H2O2 with respect to the other metal-specific Fe superoxide dismutase isoenzymes. After incubation with high amounts of H2O2 the enzyme maintains more than 40% of the initial activity. The activity of the Val 73 --> Trp mutant drastically decreases to less than 5% of the initial activity after incubation with hydrogen peroxide. Amino acid analysis of the H2O2-treated mutant enzyme evidenced the loss of the Trp 73 residue which is shown to play a critical role in the stabilization of the monomer fold of the enzyme. On the other hand, the manganese-containing wild-type and mutant enzymes were completely resistant toward H2O2 demonstrating the specific role of iron in the inactivation process.

  6. Structures of pseudechetoxin and pseudecin, two snake-venom cysteine-rich secretory proteins that target cyclic nucleotide-gated ion channels: implications for movement of the C-terminal cysteine-rich domain

    International Nuclear Information System (INIS)

    Suzuki, Nobuhiro; Yamazaki, Yasuo; Brown, R. Lane; Fujimoto, Zui; Morita, Takashi; Mizuno, Hiroshi

    2008-01-01

    The structures of pseudechetoxin and pseudecin suggest that both proteins bind to cyclic nucleotide-gated ion channels in a manner in which the concave surface occludes the pore entrance. Cyclic nucleotide-gated (CNG) ion channels play pivotal roles in sensory transduction by retinal photoreceptors and olfactory neurons. The elapid snake toxins pseudechetoxin (PsTx) and pseudecin (Pdc) are the only known protein blockers of CNG channels. These toxins belong to a cysteine-rich secretory protein (CRISP) family containing an N-terminal pathogenesis-related proteins of group 1 (PR-1) domain and a C-terminal cysteine-rich domain (CRD). PsTx and Pdc are highly homologous proteins, but their blocking affinities on CNG channels are different: PsTx blocks both the olfactory and retinal channels with ∼15–30-fold higher affinity than Pdc. To gain further insights into their structure and function, the crystal structures of PsTx, Pdc and Zn 2+ -bound Pdc were determined. The structures revealed that most of the amino-acid-residue differences between PsTx and Pdc are located around the concave surface formed between the PR-1 domain and the CRD, suggesting that the concave surface is functionally important for CNG-channel binding and inhibition. A structural comparison in the presence and absence of Zn 2+ ion demonstrated that the concave surface can open and close owing to movement of the CRD upon Zn 2+ binding. The data suggest that PsTx and Pdc occlude the pore entrance and that the dynamic motion of the concave surface facilitates interaction with the CNG channels

  7. Structures of pseudechetoxin and pseudecin, two snake-venom cysteine-rich secretory proteins that target cyclic nucleotide-gated ion channels: implications for movement of the C-terminal cysteine-rich domain

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Nobuhiro [Department of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572 (Japan); Department of Biochemistry, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602 (Japan); Yamazaki, Yasuo [Department of Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588 (Japan); Brown, R. Lane [Neurological Science Institute, Oregon Health and Science University, Beaverton, Oregon 97006 (United States); Fujimoto, Zui [Department of Biochemistry, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602 (Japan); Morita, Takashi, E-mail: tmorita@my-pharm.ac.jp [Department of Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588 (Japan); Mizuno, Hiroshi, E-mail: tmorita@my-pharm.ac.jp [Department of Biochemistry, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602 (Japan); VALWAY Technology Center, NEC Soft Ltd, Koto-ku, Tokyo 136-8627 (Japan); Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Central 6, Tsukuba, Ibaraki 305-8566 (Japan); Department of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572 (Japan)

    2008-10-01

    The structures of pseudechetoxin and pseudecin suggest that both proteins bind to cyclic nucleotide-gated ion channels in a manner in which the concave surface occludes the pore entrance. Cyclic nucleotide-gated (CNG) ion channels play pivotal roles in sensory transduction by retinal photoreceptors and olfactory neurons. The elapid snake toxins pseudechetoxin (PsTx) and pseudecin (Pdc) are the only known protein blockers of CNG channels. These toxins belong to a cysteine-rich secretory protein (CRISP) family containing an N-terminal pathogenesis-related proteins of group 1 (PR-1) domain and a C-terminal cysteine-rich domain (CRD). PsTx and Pdc are highly homologous proteins, but their blocking affinities on CNG channels are different: PsTx blocks both the olfactory and retinal channels with ∼15–30-fold higher affinity than Pdc. To gain further insights into their structure and function, the crystal structures of PsTx, Pdc and Zn{sup 2+}-bound Pdc were determined. The structures revealed that most of the amino-acid-residue differences between PsTx and Pdc are located around the concave surface formed between the PR-1 domain and the CRD, suggesting that the concave surface is functionally important for CNG-channel binding and inhibition. A structural comparison in the presence and absence of Zn{sup 2+} ion demonstrated that the concave surface can open and close owing to movement of the CRD upon Zn{sup 2+} binding. The data suggest that PsTx and Pdc occlude the pore entrance and that the dynamic motion of the concave surface facilitates interaction with the CNG channels.

  8. Channel Communication and Reconfigurable Hardware

    NARCIS (Netherlands)

    Bos, M.; Havinga, Paul J.M.; Smit, Gerardus Johannes Maria; Karelse, F.

    2000-01-01

    Many applications can be structured as a set of processes or threads that communicate via channels. These threads can be executed on various platforms (e.g. general purpose CPU, DSP, FPGA, etc). In our research we apply channels as a basic communication mechanism between threads in a reconfigurable

  9. Feasibility of attaining uniform grain structure and enhanced ductility in aluminum alloy by employing a beveled punch in equal-channel angular pressing

    Energy Technology Data Exchange (ETDEWEB)

    Nejadseyfi, Omid, E-mail: o.nejadseyfi@gmail.com [Advanced Materials and Nanotechnology Research Lab, Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shokuhfar, Ali [Advanced Materials and Nanotechnology Research Lab, Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Sadeghi, Seyedali [Department of Mechanical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2016-01-10

    The advantage of using a beveled-edge punch in equal-channel angular pressing is investigated. Lambda angle (λ), the clockwise angle between the theoretical shear plane and punch/billet interface, is used to demonstrate how the punch tip is inclined. Transmission electron microscope is used to assess the microstructure of the samples processed using a beveled-edge punch. In addition, tensile tests at elevated temperature are performed. The results show that using a beveled-edge punch (λ=90°) in the process leads to formation of uniform subgrain structure and increases the tensile ductility for the samples at elevated temperature. Additionally, finite element simulations are performed to study the correlation between measured properties and mechanism of material deformation by employing a beveled-edge punch. Numerical simulations confirm the irregular deformation in case of λ=0° and uniform strain distribution for λ=90°, which were the main reasons of variation in mechanical properties.

  10. Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber.

    Directory of Open Access Journals (Sweden)

    Nikodemus Gessele

    Full Text Available Naked mole-rats (Heterocephalus glaber live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.

  11. Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber).

    Science.gov (United States)

    Gessele, Nikodemus; Garcia-Pino, Elisabet; Omerbašić, Damir; Park, Thomas J; Koch, Ursula

    2016-01-01

    Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.

  12. Focused-ion-beam nano-structured rib channel waveguides in KY(WO4)2 for laser applications

    NARCIS (Netherlands)

    Gardillou, F.; Romanyuk, Y.E.; Pavius, M.; Borca, C.N.; Salathé, R.P.; Pollnau, Markus

    2006-01-01

    Bulk $KY(WO_4)_2$ (hereafter KYW) laser crystals doped with rare-earth ions are recognized to be among the most promising host materials for obtaining novel solid-state lasers. The rare-earth ions $RE^{3+}$ are easily incorporated in the KYW structure by replacing the $Y{3+}$ ions, resulting in a

  13. Microsecond simulations of the folding/unfolding thermodynamics of the Trp-cage mini protein

    Science.gov (United States)

    Day, Ryan; Paschek, Dietmar; Garcia, Angel E.

    2012-01-01

    We study the unbiased folding/unfolding thermodynamics of the Trp-cage miniprotein using detailed molecular dynamics simulations of an all-atom model of the protein in explicit solvent, using the Amberff99SB force field. Replica-exchange molecular dynamics (REMD) simulations are used to sample the protein ensembles over a broad range of temperatures covering the folded and unfolded states, and at two densities. The obtained ensembles are shown to reach equilibrium in the 1 μs per replica timescale. The total simulation time employed in the calculations exceeds 100 μs. Ensemble averages of the fraction folded, pressure, and energy differences between the folded and unfolded states as a function of temperature are used to model the free energy of the folding transition, ΔG(P,T), over the whole region of temperature and pressures sampled in the simulations. The ΔG(P,T) diagram describes an ellipse over the range of temperatures and pressures sampled, predicting that the system can undergo pressure induced unfolding and cold denaturation at low temperatures and high pressures, and unfolding at low pressures and high temperatures. The calculated free energy function exhibits remarkably good agreement with the experimental folding transition temperature (Tf = 321 K), free energy and specific heat changes. However, changes in enthalpy and entropy are significantly different than the experimental values. We speculate that these differences may be due to the simplicity of the semi-empirical force field used in the simulations and that more elaborate force fields may be required to describe appropriately the thermodynamics of proteins. PMID:20408169

  14. Single-channel kinetics of BK (Slo1 channels

    Directory of Open Access Journals (Sweden)

    Yanyan eGeng

    2015-01-01

    Full Text Available Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1 channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD attached to four surrounding transmembrane voltage sensing domains (VSD and a large intracellular cytosolic domain (CTD, also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with 5 closed states on the upper tier and 5 open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states.

  15. Effect of equal channel angular pressing on structure and superplasticity of non-heat hardenable Al-Mg-Sc-Zr alloy

    Science.gov (United States)

    Mukhametdinova, Oksana; Avtokratova, Elena; Sitdikov, Oleg; Markushev, Michael

    2015-10-01

    Microstructure and superplastic behavior of the aluminum alloy 1570C (Al-5Mg-0.2Sc-0.08Zr) after equal channel angular pressing (ECAP) to the strains of e ˜ 3 and 8 at the temperature of 325°C have been analyzed. ECAP to e ˜ 3 resulted in the partially recrystallized structure with the volume fraction and size of new grains of about 30% and 1-2 µm, consequently. The alloy with such structure exhibited the high-strain rate superplasticity with elongations >2000% at strain rates ˜10-2 s-1 and temperatures 475-520°C. After ECAP to e ˜ 8, the structure became more uniform with ˜70% of grains of ˜1 μm in size. This promoted both low-temperature and high-strain rate superplasticity with maximum elongations ˜1000 and 3300% at 350°C and 1.4×10-2 s-1 and at 475°C and 5.6×10-2 s-1, respectively. The nature of the alloy superplastic behavior is discussed.

  16. Identification of Potent Chloride Intracellular Channel Protein 1 Inhibitors from Traditional Chinese Medicine through Structure-Based Virtual Screening and Molecular Dynamics Analysis

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-01-01

    Full Text Available Chloride intracellular channel 1 (CLIC1 is involved in the development of most aggressive human tumors, including gastric, colon, lung, liver, and glioblastoma cancers. It has become an attractive new therapeutic target for several types of cancer. In this work, we aim to identify natural products as potent CLIC1 inhibitors from Traditional Chinese Medicine (TCM database using structure-based virtual screening and molecular dynamics (MD simulation. First, structure-based docking was employed to screen the refined TCM database and the top 500 TCM compounds were obtained and reranked by X-Score. Then, 30 potent hits were achieved from the top 500 TCM compounds using cluster and ligand-protein interaction analysis. Finally, MD simulation was employed to validate the stability of interactions between each hit and CLIC1 protein from docking simulation, and Molecular Mechanics/Generalized Born Surface Area (MM-GBSA analysis was used to refine the virtual hits. Six TCM compounds with top MM-GBSA scores and ideal-binding models were confirmed as the final hits. Our study provides information about the interaction between TCM compounds and CLIC1 protein, which may be helpful for further experimental investigations. In addition, the top 6 natural products structural scaffolds could serve as building blocks in designing drug-like molecules for CLIC1 inhibition.

  17. ZnO-channel thin-film transistors: Channel mobility

    International Nuclear Information System (INIS)

    Hoffman, R.L.

    2004-01-01

    ZnO-channel thin-film transistor (TFT) test structures are fabricated using a bottom-gate structure on thermally oxidized Si; ZnO is deposited via RF sputtering from an oxide target, with an unheated substrate. Electrical characteristics are evaluated, with particular attention given to the extraction and interpretation of transistor channel mobility. ZnO-channel TFT mobility exhibits severe deviation from that assumed by ideal TFT models; mobility extraction methodology must accordingly be recast so as to provide useful insight into device operation. Two mobility metrics, μ avg and μ inc , are developed and proposed as relevant tools in the characterization of nonideal TFTs. These mobility metrics are employed to characterize the ZnO-channel TFTs reported herein; values for μ inc as high as 25 cm2/V s are measured, comprising a substantial increase in ZnO-channel TFT mobility as compared to previously reported performance for such devices

  18. Channels in tokamak reactor shields

    International Nuclear Information System (INIS)

    Shchipakin, O.L.

    1981-01-01

    The results of calculations of neutron transport through the channels in the tokamak reactor radiation shields, obtained by the Monte Carlo method and by the method of discrete ordinates, are considered. The given data show that the structural materials of the channel and that of the blanket and shields in the regions close to it are subjected to almost the same irradiation as the first wall and therefore they should satisfy the technical requirements. The radiation energy release in the injector channel wall, caused by neutron shooting, substantially depends on the channel dimensions. At the channel large diameter (0.7-10 m) this dependence noticeably decreases. The investigation of the effect of the injector channel cross section form on the neutron flux density through the channel, testifies to weak dependence of shooting radiation intensity on the form of the channel cross section. It is concluded that measures to decrease unfavourable effect of the channels on the safety of the power tokamak reactor operation and maintenance cause substantial changes in reactor design due to which the channel protection must be developed at first stages. The Monte Carlo method is recommended to be used for variant calculations and when calculating the neutron flux functionals in specific points of the system the discrete ordinate method is preferred [ru

  19. Re-introduction of structurally complex wood jams promotes channel and habitat recovery from overwidening: Implications for river conservation

    OpenAIRE

    Harvey, G.; Henshaw, A.; Parker, C.; Sayer, C.

    2017-01-01

    1. Large wood is a powerful geomorphic agent in rivers, providing important habitat functions for a range of aquatic organisms, but has been subject to a long history of removal.\\ud 2. Internationally, approaches to river restoration are increasingly incorporating large wood features, but generally favour simple flow deflectors (e.g. single logs, stripped of branches and anchored in place) over more complex structures that more accurately mimic natural wood jams.\\ud 3. This paper explores cha...

  20. Sensory effects of transient receptor potential channel agonists on whole mouth saliva extensional rheology.

    Science.gov (United States)

    Houghton, Jack William; Hans, Joachim; Pesaro, Manuel; Ley, Jakob Peter; Carpenter, Guy Howard; Proctor, Gordon

    2017-08-01

    The extensional rheology (ER) of saliva is a property associated with its ability to coat surfaces and is important for the maintenance of a normal mouth feeling. Transient receptor potential (TRP) channels are expressed in the oral cavity and this study investigated how the sensory effects of TRP channel agonists modify the ER of saliva. Healthy volunteers rinsed with solutions containing a TRP agonist. Unstimulated whole mouth saliva (WMS) was collected prior to rinsing and WMS was collected during the first and second minutes after the mouth rinse. The Spinnbarkeit of the collected saliva was measured using a Neva Meter. The nonivamide (TRPV1) mouth rinse increased WMS ER from 37.0 (± 6.3) mm to 49.3 (± 5.1) mm when compared with the vehicle control, which itself had no effect on WMS ER. However, this effect was short-lived and ER of WMS was not increased in the second minute after the nonivamide mouth rinse. The menthol (TRPM8) mouth rinse resulted in an increase up to 57.8 (± 7.8) mm in WMS ER from the vehicle control and returned to control levels in the second minute. The cinnamaldehyde (TRPA1) mouth rinse resulted in no change in WMS ER. It can be concluded that nonivamide and menthol mouth rinsing has a short-term effect of increasing WMS ER, an effect not observed after cinnamaldehyde rinsing. We hypothesize that the activation of some TRP channels in the oral cavity results in changes in the salivary protein composition that in turn alters WMS ER. Identifying compounds that modify the physical properties of saliva in a desirable way is important in developing treatments for conditions associated with changes in the physical properties of saliva such as xerostomia (also known as dry mouth). Furthermore, understanding the rheology of saliva contributes to the elucidation of food oral processing which is of importance to food manufacturers. © 2017 Wiley Periodicals, Inc.

  1. Ion channelling in diamond

    International Nuclear Information System (INIS)

    Derry, T.E.

    1978-06-01

    Diamond is one of the most extreme cases from a channelling point of view, having the smallest thermal vibration amplitude and the lowest atomic number of commonly-encountered crystals. These are the two parameters most important for determining channelling behaviour. It is of consiberable interest therefore to see how well the theories explaining and predicting the channeling properties of other substance, succeed with diamond. Natural diamond, although the best available form for these experiments, is rather variable in its physical properties. Part of the project was devoted to considering and solving the problem of obtaining reproducible results representative of the ideal crystal. Channelling studies were performed on several good crystals, using the Rutherford backscattering method. Critical angles for proton channelling were measured for incident energies from 0.6 to 4.5 MeV, in the three most open axes and three most open planes of the diamond structure, and for α-particle channelling at 0.7 and 1.0 MeV (He + ) in the same axes and planes. For 1.0 MeV protons, the crystal temperature was varied from 20 degrees Celsius to 700 degrees Celsius. The results are presented as curves of backscattered yield versus angle in the region of each axis or plane, and summarised in the form of tables and graphs. Generally the critical angles, axial minimum yields, and temperature dependence are well predicted by the accepted theories. The most valuable overall conclusion is that the mean thermal vibration amplitude of the atoms in a crytical determines the critical approach distance to the channel walls at which an ion can remain channelled, even when this distance is much smaller than the Thomas-Fermi screening distance of the atomic potential, as is the case in diamond. A brief study was made of the radiation damage caused by α-particle bombardment, via its effect on the channelling phenomenon. It was possible to hold damage down to negligible levels during the

  2. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  3. Phenolphthalein as a prototype drug for a group of structurally related calcium channel blockers in human platelets.

    Science.gov (United States)

    Dobrydneva, Yuliya; Wilson, Emily; Abelt, Christopher J; Blackmore, Peter F

    2009-03-01

    Thrombin increases intracellular free Ca ([Ca]i) in human platelets by 2 mechanisms: internal mobilization and the influx of Ca via store-operated Ca entry (SOCE). 2-Aminoethoxydiphenyl borate (2-APB) is an inhibitor of SOCE. In search for nonboron analogues of 2-APB, we identified a well-known compound, phenolphthalein, structurally related to 2-APB. Many phenolphthalein analogues inhibited the ability of thrombin and thapsigargin (a specific activator of SOCE) to increase [Ca]i. Phenolphthalein has an IC50 approximately 10 microM to inhibit thrombin-induced [Ca]i elevation, its active analogues have a similar potency. Several phenolphthalein analogues also inhibited thrombin-induced intracellular Ca mobilization, which indicates action on inositol 1,4,5-trisphosphate receptors. We identified structural features among active and inactive phenolphthalein analogues that are responsible for the activity. Opening of the 5-membered lactone ring of phenolphthalein resulted in a total loss of activity. If the diphenyl rings possessed primary amine, dimethyl amine, or a cyano group, there was no activity. Modifications to the diphenyl groups that were tolerated include phosphate, sulfate, iodine, bromine, methyl, nitrite, and methoxy. Inhibition of thrombin-induced [Ca]i increase by phenolphthalein was not mediated by an increase in cyclic adenosine monophosphate because the inhibitor of cyclic adenosine monophosphate-dependent protein kinase A, 4-cyano-3-methylisoquinoline, did not affect the inhibitory action of phenolphthalein. The inhibitory effect of phenolphthalein was not mediated by an increase in NO/cyclic guanosine monophosphate (cGMP) because the inhibitors of NO-sensitive soluble guanylyl cyclase, methylene blue, and ODQ did not affect the inhibition. Phytohemagglutinin and thapsigargin-induced SOCE in Jurkat cells was also inhibited by phenolphthalein and 2-APB to the same extent as seen in platelets. Therefore, phenolphthalein and its derivatives

  4. CaSeO4-0.625H2O - Water Channel Occupation in a bassanite Related Structure

    Energy Technology Data Exchange (ETDEWEB)

    S Fritz; H Schmidt; I Paschke; O Magdysyuk; R Dinnebier; D Freyer; W Voigt

    2011-12-31

    Calcium selenate subhydrate, CaSeO{sub 4} {center_dot} 0.625H{sub 2}O, was prepared by hydrothermal conversion of CaSeO{sub 4} {center_dot} 2H{sub 2}O at 463 K. From the single crystals obtained in the shape of hexagonal needles, 50-300 {micro}m in length, the crystal structure could be solved in a trigonal unit cell with space group P3{sub 2}21. The cell was confirmed and refined by high-resolution synchrotron powder diffraction. The subhydrate was characterized by thermal analysis and Raman spectroscopy.

  5. Starburst Channels

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1 Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies. In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out. Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  6. Population structure and maturity stages of Fritillaria borealis (Appendicularia, Tunicata: seasonal cycle in Ushuaia Bay (Beagle Channel

    Directory of Open Access Journals (Sweden)

    María Laura Presta

    2015-09-01

    Full Text Available AbstractFritillaria borealis is a cosmopolitan species, very frequent in sub-antarctic and antarctic waters. The objective of this paper was to analyze its size structure and maturity stages at two sites in Ushuaia Bay: a coastal site exposed to anthropogenic pressure (E1 and a reference site (E2 located in the external zone of the bay. Zooplankton was collected during the 2012 seasonal cycle. The sampling method involved the use of a 67 µm-mesh net. Appendicularians were classified in four maturity stages: I undifferentiated gonads, II testis and ovary differentiated, III expanded testis, IV discharged testis, expanded ovary. Our results showed that the highest densities of F. borealisoccurred in spring and summer at both sites; coinciding with high values of chlorophyll-a. The percentage of juveniles (I and II exhibited a spatial and temporal pattern similar to that observed for chlorophyll-a values. During spring-summer, juveniles and mature specimens (III and IV showed a greater gonadal development than those individuals found in autumn-winter. In conclusion, the mismatching in the population structure and the pattern of densities of F. borealis between coastal and external zones would suggest the existence of two sub-populations susceptible to the influence of the anthropogenic impact in the bay.

  7. Structure of Arabidopsis Dehydroquinate Dhydratase-Shikimate Dehydrogeanse and Implications for Metabolic Channeling in the Shikimate Pathway

    International Nuclear Information System (INIS)

    Singh, S.; Christendat, D.

    2006-01-01

    The bifunctional enzyme dehydroquinate dehydratase-shikimate dehydrogenase (DHQ-SDH) catalyzes the dehydration of dehydroquinate to dehydroshikimate and the reduction of dehydroshikimate to shikimate in the shikimate pathway. We report the first crystal structure of Arabidopsis DHQ-SDH with shikimate bound at the SDH site and tartrate at the DHQ site. The interactions observed in the DHQ-tartrate complex reveal a conserved mode for substrate binding between the plant and microbial DHQ dehydratase family of enzymes. The SDH-shikimate complex provides the first direct evidence of the role of active site residues in the catalytic mechanism. Site-directed mutagenesis and mechanistic analysis revealed that Asp 423 and Lys 385 are key catalytic groups and Ser 336 is a key binding group. The arrangement of the two functional domains reveals that the control of metabolic flux through the shikimate pathway is achieved by increasing the effective concentration of dehydroshikimate through the proximity of the two sites

  8. Design, synthesis and anti-HIV evaluation of novel diarylnicotinamide derivatives (DANAs) targeting the entrance channel of the NNRTI binding pocket through structure-guided molecular hybridization.

    Science.gov (United States)

    Liu, Zhaoqiang; Chen, Wenmin; Zhan, Peng; De Clercq, Erik; Pannecouque, Christophe; Liu, Xinyong

    2014-11-24

    Through a structure-based molecular hybridization approach, a novel series of diarylnicotinamide derivatives (DANAs) targeting the entrance channel of HIV-1 NNRTIs binding pocket (NNIBP) were rationally designed, synthesized and evaluated for their anti-HIV activities in MT-4 cells together with the inhibition against the reverse transcriptase (RT) in an enzymatic assay. Encouragingly, most of the new DANAs were found to be active against wild-type HIV-1 with an EC50 in the range of 0.027-4.54 μM. Among them, compound 6b11 (EC50 = 0.027 μM, SI > 12518) and 6b5 (EC50 = 0.029 μM, SI = 2471) were identified as the most potent inhibitors, which were more potent than the reference drugs nevirapine (EC50 = 0.31 μM) and delavirdine (EC50 = 0.66 μM). Some DANAs were also active at micromolar concentrations against the K103N + Y181C resistant mutant. Compound 6b11 exhibited the highest enzymatic inhibition activity (IC50 = 20 nM), which is equal to that of efavirenz (EC50 = 20 nM) and 31 times higher than that of nevirapine (EC50 = 0.62 μM). Preliminary structure-activity relationships (SARs) and molecular modeling of these new DANAs have been discussed. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  9. Plasma membrane calcium channels in cancer: Alterations and consequences for cell proliferation and migration.

    Science.gov (United States)

    Déliot, Nadine; Constantin, Bruno

    2015-10-01

    The study of calcium channels in molecular mechanisms of cancer transformation is still a novel area of research. Several studies, mostly conducted on cancer cell lines, however support the idea that a diversity of plasma membrane channels participates in the remodeling of Ca2+ homeostasis, which regulates various cancer hallmarks such as uncontrolled multiplication and increase in migration and invasion abilities. However few is still understood concerning the intracellular signaling cascades mobilized by calcium influx participating to cancer cell behavior. This review intends to gather some of these pathways dependent on plasma membrane calcium channels and described in prostate, breast and lung cancer cell lines. In these cancer cell types, the calcium channels involved in calcium signaling pathways promoting cancer behaviors are mostly non-voltage activated calcium channels and belong to the TRP superfamily (TRPC, TPRPV and TRPM families) and the Orai family. TRP and Orai channels are part of many signaling cascades involving the activation of transmembrane receptors by extracellular ligand from the tumor environment. TRPV can sense changes in the physical and chemical environment of cancer cells and TRPM7 are stretch activated and sensitive to cholesterol. Changes in activation and or expression of plasma-membrane calcium channels affect calcium-dependent signaling processes relevant to tumorigenesis. The studies cited in this review suggest that an increase in plasma membrane calcium channel expression and/or activity sustain an elevated calcium entry (constitutive or under the control of extracellular signals) promoting higher cell proliferation and migration in most cases. A variety of non-voltage-operated calcium channels display change expression and/or activity in a same cancer type and cooperate to the same process relevant to cancer cell behavior, or can be involved in a different sequence of events during the tumorigenesis. This article is part of a

  10. Involvement of the TRPV1 channel in the modulation of spontaneous locomotor activity, physical performance and physical exercise-induced physiological responses

    Directory of Open Access Journals (Sweden)

    A.S.R. Hudson

    2016-01-01

    Full Text Available Physical exercise triggers coordinated physiological responses to meet the augmented metabolic demand of contracting muscles. To provide adequate responses, the brain must receive sensory information about the physiological status of peripheral tissues and organs, such as changes in osmolality, temperature and pH. Most of the receptors involved in these afferent pathways express ion channels, including transient receptor potential (TRP channels, which are usually activated by more than one type of stimulus and are therefore considered polymodal receptors. Among these TRP channels, the TRPV1 channel (transient receptor potential vanilloid type 1 or capsaicin receptor has well-documented functions in the modulation of pain sensation and thermoregulatory responses. However, the TRPV1 channel is also expressed in non-neural tissues, suggesting that this channel may perform a broad range of functions. In this review, we first present a brief overview of the available tools for studying the physiological roles of the TRPV1 channel. Then, we present the relationship between the TRPV1 channel and spontaneous locomotor activity, physical performance, and modulation of several physiological responses, including water and electrolyte balance, muscle hypertrophy, and metabolic, cardiovascular, gastrointestinal, and inflammatory responses. Altogether, the data presented herein indicate that the TPRV1 channel modulates many physiological functions other than nociception and thermoregulation. In addition, these data open new possibilities for investigating the role of this channel in the acute effects induced by a single bout of physical exercise and in the chronic effects induced by physical training.

  11. TRPM5 is a voltage-modulated and Ca(2+)-activated monovalent selective cation channel.

    Science.gov (United States)

    Hofmann, Thomas; Chubanov, Vladimir; Gudermann, Thomas; Montell, Craig

    2003-07-01

    The TRPM subfamily of mammalian TRP channels displays unusually diverse activation mechanisms and selectivities. One member of this subfamily, TRPM5, functions in taste receptor cells and has been reported to be activated through G protein-coupled receptors linked to phospholipase C. However, the specific mechanisms regulating TRPM5 have not been described. Here, we demonstrate that TRPM5 is a monovalent-specific cation channel with a 23 pS unitary conductance. TRPM5 does not display constitutive activity. Rather, it is activated by stimulation of a receptor pathway coupled to phospholipase C and by IP(3)-mediated Ca(2+) release. Gating of TRPM5 was dependent on a rise in Ca(2+) because it was fully activated by Ca(2+). Unlike any previously described mammalian TRP channel, TRPM5 displayed voltage modulation and rapid activation and deactivation kinetics upon receptor stimulation. The most closely related protein, the Ca(2+)-activated monovalent-selective cation channel TRPM4b, also showed voltage modulation, although with slower relaxation kinetics than TRPM5. Taken together, the data demonstrate that TRPM5 and TRPM4b represent the first examples of voltage-modulated, Ca(2+)-activated, monovalent cation channels (VCAMs). The voltage modulation and rapid kinetics provide TRPM5 with an excellent set of properties for participating in signaling in taste receptors and other excitable cells.

  12. BK channel modulators: a comprehensive overview

    DEFF Research Database (Denmark)

    Nardi, Antonio; Olesen, Søren-Peter

    2008-01-01

    The large Ca(2+)-activated K(+) channel (BK channel) reflects per excellence the dilemma of the molecular target driven drug discovery process. Significant experimental evidence suggests that the BK channels play a pivotal and specific role in many pathophysiological conditions supporting...... the notion that the channel represents an innovative and promising drug target. However, after more than ten years of intense research effort both in academia and industry, scientists have yet to witness the approval of a single BK channel modulator for clinical use. On the contrary, three BK openers...... and blockers 4) Marketed and/or investigational drugs with BK-modulating side properties and structural analogues 5) Naturally-occurring BK channel openers and structural analogues 6) Synthetic BK channel openers. This review is intended to provide readers with current opinion on the BK channel as a drug...

  13. Investigation of KIF6 Trp719Arg in a case-control study of myocardial infarction: a Costa Rican population.

    Directory of Open Access Journals (Sweden)

    Lance A Bare

    2010-09-01

    Full Text Available The 719Arg allele of KIF6 (rs20455 was associated with coronary events in Caucasian participants of five prospective studies. We investigated whether this KIF6 variant was associated with non-fatal myocardial infarction (MI in a case-control study of an admixed population from the Central Valley of Costa Rica. Genotypes of the KIF6 variant were determined for 4,134 men and women. Cases (1,987 had survived a first MI; controls (2,147 had no history of MI and were matched to cases by age, sex, and area of residence. We tested the association between the KIF6 719Arg allele and non-fatal MI by conditional logistic regression and adjusted for admixture of founder populations.Compared with the reference Trp/Trp homozygotes, KIF6 719Arg carriers were not at significantly higher risk for non-fatal MI in this study after adjustment for traditional risk factors or admixture (OR= 1.12; 95%CI, 0.98-1.28. Heterozygotes of the KIF6 Trp719Arg variant were at increased risk of non-fatal MI: the adjusted odds ratio was 1.16 (95% confidence interval, 1.01-1.34, but this association would not be significant after a multiple testing correction.We found that carriers of the KIF6 719Arg allele were not at increased risk of non-fatal MI in a case-control study of Costa Ricans living in the Central Valley of Costa Rica.

  14. Trp64Arg polymorphism of the ADRB3 gene associated with maximal fat oxidation and LDL-C levels in non-obese adolescents.

    Science.gov (United States)

    Jesus, Íncare Correa de; Alle, Lupe Furtado; Munhoz, Eva Cantalejo; Silva, Larissa Rosa da; Lopes, Wendell Arthur; Tureck, Luciane Viater; Purim, Katia Sheylla Malta; Titski, Ana Claudia Kapp; Leite, Neiva

    2017-09-21

    To analyze the association between the Trp64Arg polymorphism of the ADRB3 gene, maximal fat oxidation rates and the lipid profile levels in non-obese adolescents. 72 schoolchildren, of both genders, aged between 11 and 17 years, participated in the study. The anthropometric and body composition variables, in addition to total cholesterol, HDL-c, LDL-c, triglycerides, insulin, and basal glycemia, were evaluated. The sample was divided into two groups according to the presence or absence of the polymorphism: non-carriers of the Arg64 allele, i.e., homozygous (Trp64Trp: n=54), and carriers of the Arg64 allele (Trp64Arg+Arg64Arg: n=18), in which the frequency of the Arg64 allele was 15.2%. The maximal oxygen uptake and peak of oxygen uptake during exercise were obtained through the symptom-limited, submaximal treadmill test. Maximal fat oxidation was determined according to the ventilatory ratio proposed in Lusk's table. Adolescents carrying the less frequent allele (Trp64Arg and Arg64Arg) had higher LDL-c levels (p=0.031) and lower maximal fat oxidation rates (p=0.038) when compared with non-carriers (Trp64Trp). Although the physiological processes related to lipolysis and lipid metabolism are complex, the presence of the Arg 64 allele was associated with lower rates of FATMAX during aerobic exercise, as well as with higher levels of LDL-c in adolescents. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  15. Variations in grain-scale sediment structure and entrainment force in a gravel-bed channel as a function of fine sediment content and morphological location

    Science.gov (United States)

    Voepel, Hal; Ahmed, Sharif; Hodge, Rebecca; Leyland, Julian; Sear, David

    2017-04-01

    One of the major causes of uncertainty in estimates of bedload transport rates in gravel-bed rivers is a lack of understanding of grain-scale sediment structure, and the impact that this structure has on the force required to entrain sediment. There are at least two factors that standard entrainment models do not consider. The first is the way in which the spatial arrangement and orientation of grains and the resultant forces varies throughout a channel and over time, ways that have yet to be fully quantified. The second is that sediment entrainment is a 3D process, yet calculations of entrainment thresholds for sediment grains are typically based on 2D diagrams where we calculate static moments of force vectors about a pivot angle, represented as a single point rather than as a more realistic axis of rotation. Our research addresses these limitations by quantifying variations in 3D sediment structure and entrainment force requirements across two key parameters: morphological location within a riffle-pool sequence (reflecting variation in hydraulic conditions), and the fine sediment content of the gravel-bed (sand and clay). We report results from a series of flume experiments in which we water-worked a gravel-bed with a riffle-pool morphology containing varying amounts of fine sediment. After each experimental run intact samples of the bed at different locations were extracted and the internal structure of the bed was measured using non-destructive, micro-focus X-ray computed tomography (CT) imaging. The CT images were processed to measure the properties of individual grains, including volume, center of mass, dimension, and contact points. From these data we were able to quantify the sediment structure and entrainment force requirements through measurement of 3D metrics including grain pivot angles, grain exposure and protrusion. Comparison of the metrics across different morphological locations and fine sediment content demonstrates how these factors affect the

  16. Three-dimensional structure of the Rhodobacter sphaeroides RC-LH1-PufX complex: dimerization and quinone channels promoted by PufX.

    Science.gov (United States)

    Qian, Pu; Papiz, Miroslav Z; Jackson, Philip J; Brindley, Amanda A; Ng, Irene W; Olsen, John D; Dickman, Mark J; Bullough, Per A; Hunter, C Neil

    2013-10-29

    Reaction center-light harvesting 1 (RC-LH1) complexes are the fundamental units of bacterial photosynthesis, which use solar energy to power the reduction of quinone to quinol prior to the formation of the proton gradient that drives ATP synthesis. The dimeric RC-LH1-PufX complex of Rhodobacter sphaeroides is composed of 64 polypeptides and 128 cofactors, including 56 LH1 bacteriochlorophyll a (BChl a) molecules that surround and donate energy to the two RCs. The 3D structure was determined to 8 Å by X-ray crystallography, and a model was built with constraints provided by electron microscopy (EM), nuclear magnetic resonance (NMR), mass spectrometry (MS), and site-directed mutagenesis. Each half of the dimer complex consists of a RC surrounded by an array of 14 LH1 αβ subunits, with two BChls sandwiched between each αβ pair of transmembrane helices. The N- and C-terminal extrinsic domains of PufX promote dimerization by interacting with the corresponding domains of an LH1 β polypeptide from the other half of the RC-LH1-PufX complex. Close contacts between PufX, an LH1 αβ subunit, and the cytoplasmic domain of the RC-H subunit prevent the LH1 complex from encircling the RC and create a channel connecting the RC QB site to an opening in the LH1 ring, allowing Q/QH₂ exchange with the external quinone pool. We also identified a channel that connects the two halves of the dimer, potentially forming a long-range pathway for quinone migration along rows of RC-LH1-PufX complexes in the membrane. The structure of the RC-LH1-PufX complex explains the crucial role played by PufX in dimer formation, and it shows how quinone traffic traverses the LH1 complex as it shuttles between the RC and the cytochrome bc₁ complex.

  17. Localization of transient receptor potential ion channels in primary and motile cilia of the female murine reproductive organs

    DEFF Research Database (Denmark)

    Teilmann, Stefan C.; Byskov, Anne Grete; Pedersen, Per Amstrup

    2005-01-01

    We have examined the subcellular localization of transient receptor potential (TRP) ion channels and the potential sensory role of cilia in murine female reproductive organs using confocal laser scanning microscopy analysis on ovary and oviduct tissue sections as well as on primary cultures of fo...... differentiation and in development and maturation of ovarian follicles. In the oviduct both TRPV4 and polycystins could be important in relaying physiochemical changes in the oviduct upon ovulation. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc....

  18. A transient receptor potential channel expressed in taste receptor cells.

    Science.gov (United States)

    Pérez, Cristian A; Huang, Liquan; Rong, Minqing; Kozak, J Ashot; Preuss, Axel K; Zhang, Hailin; Max, Marianna; Margolskee, Robert F

    2002-11-01

    We used differential screening of cDNAs from individual taste receptor cells to identify candidate taste transduction elements in mice. Among the differentially expressed clones, one encoded Trpm5, a member of the mammalian family of transient receptor potential (TRP) channels. We found Trpm5 to be expressed in a restricted manner, with particularly high levels in taste tissue. In taste cells, Trpm5 was coexpressed with taste-signaling molecules such as alpha-gustducin, Ggamma13, phospholipase C-beta2 (PLC-beta2) and inositol 1,4,5-trisphosphate receptor type III (IP3R3). Our heterologous expression studies of Trpm5 indicate that it functions as a cationic channel that is gated when internal calcium stores are depleted. Trpm5 may be responsible for capacitative calcium entry in taste receptor cells that respond to bitter and/or sweet compounds.

  19. Morphology, structure, composition and build-up processes of the active channel-mouth lobe complex of the Congo deep-sea fan with inputs from remotely operated underwater vehicle (ROV) multibeam and video surveys

    Science.gov (United States)

    Dennielou, Bernard; Droz, Laurence; Babonneau, Nathalie; Jacq, Céline; Bonnel, Cédric; Picot, Marie; Le Saout, Morgane; Saout, Yohan; Bez, Martine; Savoye, Bruno; Olu, Karine; Rabouille, Christophe

    2017-08-01

    The detailed structure and composition of turbiditic channel-mouth lobes is still largely unknown because they commonly lie at abyssal water depths, are very thin and are therefore beyond the resolution of hull-mound acoustic tools. The morphology, structure and composition of the Congo turbiditic channel-mouth lobe complex (90×40 km; 2525 km2) were investigated with hull-mounted swath bathymetry, air gun seismics, 3.5 kHz sub-bottom profiler, sediment piston cores and also with high-resolution multibeam bathymetry and video acquired with a Remote Operating Vehicle (ROV). The lobe complex lies 760 km off the Congo River mouth in the Angola abyssal plain between 4740 and 5030 m deep. It is active and is fed by turbidity currents that deposit several centimetres of sediment per century. The lobe complex is subdivided into five lobes that have prograded. The lobes are dominantly muddy. Sand represents ca. 13% of the deposits and is restricted to the feeding channel and distributaries. The overall lobe body is composed of thin muddy to silty turbidites. The whole lobe complex is characterized by in situ mass wasting (slumps, debrites). The 1-m-resolution bathymetry shows pervasive slidings and block avalanches on the edges of the feeding channel and the channel mouth indicating that sliding occurs early and continuously in the lobe build-up. Mass wasting is interpreted as a consequence of very-high accumulation rates, over-steepening and erosion along the channels and is therefore an intrinsic process of lobe building. The bifurcation of feeding channels is probably triggered when the gradient in the distributaries at the top of a lobe becomes flat and when turbidity currents find their way on the higher gradient on the lobe side. It may also be triggered by mass wasting on the lobe side. When a new lobe develops, the abandoned lobes continue to collect significant turbiditic deposits from the feeding channel spillover, so that the whole lobe complex remains active. A

  20. [Regulatory role of calcium activated chloride channel in pulmonary vascular structural remodeling in rats with pulmonary arterial hypertension induced by high pulmonary blood flow].

    Science.gov (United States)

    Wang, K; Pang, Y S; Su, D Y; Ye, B B; Qin, S Y; Liu, D L; Han, Y L

    2016-09-01

    To explore the regulatory role of calcium activated chloride channel (CaCC) in vascular structural remodeling in pathogenesis of pulmonary arterial hypertension (PAH) induced by high pulmonary blood flow. An abdominal aorta and inferior vena cava shunting operation was used to induce high pulmonary blood flow and establish a PAH rat model.Seventy-five SD rats were randomly divided into normal, sham, shunt, niflumic acid (NFA) 1(0.2 mg/(kg·d))and NFA 2 (0.4 mg/(kg·d)) groups. There were 15 rats in each group. Pulmonary artery pressure and vascular structural remodeling were measured, arteriole contraction ratio among these groups were compared using vascular tone analysis system, and the electrophysiology of pulmonary artery smooth muscle cell (PASMC) was recorded using patch clamp technology. Differences between multiple groups were compared through variance analysis and that between groups with q test. Compared with normal ((14.4±1.3 ) mmHg, 1 mmHg=0.133 kPa)and sham groups ((13.5±2.3 ) mmHg), mean pulmonary artery pressure in shunt group ((27.4±2.4 ) mmHg) increased significantly (Ppulmonary artery pressure in NFA 1 group ((21.2±2.0) mmHg) and NFA 2 group ((22.3±2.0) mmHg) decreased significantly (PPulmonary vascular structural remodeling including pulmonary artery stenosis presented in shunt group. Compared with normal ((114.3±1.2)%) and sham ((115.5±1.1)%) groups, arteriole contraction ratio to 10(-5) mol/L phenylephrine in shunt group ((132.6±1.4)%) increased significantly (Ppulmonary vascular structural remodeling alleviated in NFA 1 and NFA 2 groups. Arteriole contraction ratio in NFA 1 group ((126.4±1.3)%) and NFA 2 group ((124.6±1.0)%) decreased significantly compared with shunt group (Ppulmonary arterial hypertension induced by high pulmonary blood flow through regulating membrane potential. NFA attenuate pulmonary vascular structural remodeling and pulmonary pressure through decreasing CaCC current density of PASMC membrane.

  1. [Synopsis about the hypothesis of "information channel" of channel-collateral system].

    Science.gov (United States)

    Chang, Xi-Lang

    2008-10-01

    The author of the present paper founded a theorem about the "incompleteness of single channel structure" (nerve, blood vessel, lymphatic, interspace, aperture, etc.) through quantitative and qualitative analysis about the economic information channel in the human body, which eliminates the probability of single channel structure in the information channel of channel (meridian)-collateral system. After comprehensive analysis on the current researches, the author puts forward a neodoxy, i.e., the body "information channel" structure of the channel-collateral system, mainly follows the distribution regularity of systemic statistics, and is not a single specific entity; various layers of the information channel in the main stems of the channel-collaterals are composed of optimized structure tissues. Hence, the structure of this information channel of channel-collateral system is an overall-optimized, sequential and compatible systemic structure. From this neodoxy, the author brings forward a working principle of channel-collaterals, which is supported theoretically by bio-auxology. The longitudinal distribution of the main stems of meridian-collaterals is considered to result from that in the process of the animal evolution, in the animals moving forward, the microscopic complicated movement of intracorporeal information and energy molecules is related to the forward macroscopic and non-uniform movement of organism in trans-measure. Its impulse and kinetic momentum forms a main vector in the longitudinal direction of the body (the direction of the main stem of channel-collaterals). In order to adapt to and utilize natural regularities, the main stems of the channel-collaterals gradually differentiate and evolve in the living organism, forming a whole system. The "hypothesis of biological origin of channel-collateral system" and "that of information channel of the channel-collaterals in the body" constitute a relatively complete theoretical system framework.

  2. The Pyrexia transient receptor potential channel mediates circadian clock synchronization to low temperature cycles in Drosophila melanogaster.

    Science.gov (United States)

    Wolfgang, Werner; Simoni, Alekos; Gentile, Carla; Stanewsky, Ralf

    2013-10-07

    Circadian clocks are endogenous approximately 24 h oscillators that temporally regulate many physiological and behavioural processes. In order to be beneficial for the organism, these clocks must be synchronized with the environmental cycles on a daily basis. Both light : dark and the concomitant daily temperature cycles (TCs) function as Zeitgeber ('time giver') and efficiently entrain circadian clocks. The temperature receptors mediating this synchronization have not been identified. Transient receptor potential (TRP) channels function as thermo-receptors in animals, and here we show that the Pyrexia (Pyx) TRP channel mediates temperature synchronization in Drosophila melanogaster. Pyx is expressed in peripheral sensory organs (chordotonal organs), which previously have been implicated in temperature synchronization. Flies deficient for Pyx function fail to synchronize their behaviour to TCs in the lower range (16-20°C), and this deficit can be partially rescued by introducing a wild-type copy of the pyx gene. Synchronization to higher TCs is not affected, demonstrating a specific role for Pyx at lower temperatures. In addition, pyx mutants speed up their clock after being exposed to TCs. Our results identify the first TRP channel involved in temperature synchronization of circadian clocks.

  3. Structure and properties of an Mg-0.3% ca magnesium alloy after multiaxial deformation and equal-channel angular pressing

    Science.gov (United States)

    Dobatkin, S. V.; Rokhlin, L. L.; Salishchev, G. A.; Kopylov, V. I.; Serebryany, V. N.; Stepanov, N. D.; Tarytina, I. E.; Kuroshev, I. S.; Martynenko, N. S.

    2014-11-01

    Multiaxial deformation (MAD) of an Mg-0.3% Ca alloy is performed when temperature decreases within the ranges 425-375 and 400-325°C. A decrease in the temperature at the end of MAD causes a decrease in the grain size from 7-8 to 0.5-2 μm and the spread of a sharp prismatic texture, which determine a high strength (σu = 194 MPa) and plasticity (δ = 39%). After MAD in the range 425-375°C, the Mg-0.3% Ca alloy is subjected to equal-channel angular pressing (ECAP) at temperatures of 275 and 325°C. ECAP causes a decrease in the grain size from 7-8 μm to 2 and 5 μm, respectively. The texture also changes from prismatic to tilted basal texture. This results in an increase in the strength to 170-160 MPa at plasticity δ = 25-30%. It is shown that MAD can be used as both final and preliminary processing before ECAP to form an ultrafine-grained structure in the Mg-0.3% Ca alloy.

  4. Structure, texture, and mechanical properties of an MA2-1hp magnesium alloy after two-stage equal-channel angular pressing and intermediate annealing

    Science.gov (United States)

    Serebryany, V. N.; Perezhogin, V. Yu.; Raab, G. I.; Kopylov, V. I.; Tabachkova, N. Yu.; Sirotinkin, V. P.; Dobatkin, S. V.

    2015-01-01

    The effect of two-stage equal-channel angular pressing (ECAP) on the microstructure, the texture, and the mechanical properties of an MA2-1hp magnesium alloy is analyzed. ECAP leads to the formation of a submicrocrystalline structure with an average grain size of 640 nm, which includes Mg17Al12 phase particles with an average grain size of 240 nm and a volume fracture of 5.5%. A scattered tilted basal texture forms after ECAP, and its experimental pole figures are used for calculating orientation distribution functions and determining the volume fractions of the main orientations and the Schmid factors for different deformation systems. An increased activation of basal slip is found after both the first and the second stages of ECAP. As a result of two-stage ECAP, the strength properties of the alloy that correspond to the minimum acceptable values achieved by direct compression are obtained. Ductility is 44 and 18% after the first stage of ECAP plus subsequent annealing and after the second stage, respectively, which is almost four and two times higher than the initial value. The resulting strength mechanical properties of the alloy after the first and the second ECAP stages are analyzed using the Hall-Petch relation.

  5. Appreciation of acai core of a pulp producer from Ananindeua/PA: proposal of reverse channel structure oriented by NPSW and reverse logistics

    Directory of Open Access Journals (Sweden)

    Ana Victoria da Costa Almeida

    2017-09-01

    Full Text Available The intensification of production and growth of consumption leads to generation of large amounts of waste, which is subsequently disposed of inappropriately, further polluting the environment. Within this context, the National Policy of Solid Waste (NPSW, through Reverse Logistics (RL, aims to maximize the use of resources by the sustainable production and rehabilitation of waste in production cycles. Acai, a valued-consumption commodity in domestic and international markets, is an example of a product whose potential has been underused. This article aims to enact these concepts on a producer from Para by the recycling of lump and consequent rationalization of the use of the product. A reverse channel structure was proposed, involving the phases of collection, screening, processing and disposal based on Fleishmann et al.’s model (2000, and other similar chain ractices, NPSW guidelines and additional influential factors on its construction based on Leite (1999. The results demonstrated the facilitators points and barriers faced by the producers.

  6. Can the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) be used to accurately report clinic total reproductive potential (TRP)?

    Science.gov (United States)

    Stern, Judy E; Hickman, Timothy N; Kinzer, Donna; Penzias, Alan S; Ball, G David; Gibbons, William E

    2012-04-01

    To assess whether total reproductive potential (TRP), the chance of a live birth from each fresh cycle (fresh cycle plus frozen transfers), could be calculated from the national Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) database and whether information not available in SART CORS resulted in significant changes to the TRP calculation. Retrospective study using SART CORS and clinic data. Three assisted reproductive technology clinics. Women undergoing ART. None. Two- and three-year TRPs for 2005 and 2006 were calculated according to patient age at cycle start by linking fresh to frozen cycles up to first live birth. Clinic records were used to adjust for (remove) frozen cycles that used more than one fresh cycle as a source of embryos and for any embryos donated to other patients or research or shipped to another facility before a live birth. TRP was higher than fresh per-cycle rates for most ages at all clinics, although accuracy was compromised when there were fewer than 20 cycles per category. Two- and 3-year TRPs differed in only 2 of 24 calculations. Adjusted TRPs differed less than three percentage points from unadjusted TRPs when volume was sufficient. Clinic TRP can be calculated from SART CORS. Data suggest that calculations of clinic TRP from the national dataset would be meaningful. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  7. The structures of the human calcium channel {alpha}{sub 1} subunit (CACNL1A2) and {beta} subunit (CACNLB3) genes

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yuichiro; Masuda, Kazuhiro; Li, Qing [Kyoto Univ. Faculty of Medicine (Japan)] [and others

    1995-05-20

    Calcium influx in pancreatic {beta}-cells is regulated mainly by L-type voltage-dependent calcium channels (VDCCs) and triggers insulin secretion. The {alpha}{sub 1} subunit (CACN4) and the {beta} subunit ({beta}{sub 3}) of VDCCs, both of which are expressed in pancreatic islets, are major components for the VDCC activity, and so they may play a critical role in the regulation of insulin secretion. The authors have determined the structures of the human CACN4 (CACNL1A2) and the human {beta}{sub 3} (CACNLB3) genes. The CACNL1A2 gene spans more than 155 kb and has 49 exons. Most of the positions interrupted by introns are well conserved between the CACNL1A2 gene and the previously reported L-type VDCC {alpha}{sub 1} subunit, CACNL1A1, gene. On the other hand, the CACNLB3 gene distributes in {approximately} 8 kb and comprises 13 exons, most of which are located together within {approximately} 5 kb. Comparisons of the genomic sequences of CACNL1A2 with the previously reported cDNA sequences indicate that there are a number of polymorphisms in the human CACNL1A2 gene. In addition, the PCR-SSCP procedure of exon 1 of CACNL1A2 revealed a change from 7 to 8 ATG trinucleotide repeats in a patient with noninsulin-dependent diabetes mellitus (NIDDM), resulting in an addition of methionine at the amino-terminus of CACN4. The determination of the structures of the human CACNL1A2 and CACNLB3 genes should facilitate study of the role of these genes in the development of NIDDM and also other genetic diseases such as long QT syndrome. 39 refs., 3 figs., 3 tabs.

  8. TRPM5 is a transient Ca2+-activated cation channel responding to rapid changes in [Ca2+]i.

    Science.gov (United States)

    Prawitt, Dirk; Monteilh-Zoller, Mahealani K; Brixel, Lili; Spangenberg, Christian; Zabel, Bernhard; Fleig, Andrea; Penner, Reinhold

    2003-12-09

    Transient receptor potential (TRP) proteins are a diverse family of proteins with structural features typical of ion channels. TRPM5, a member of the TRPM subfamily, plays an important role in taste receptors, although its activation mechanism remains controversial and its function in signal transduction is unknown. Here we characterize the functional properties of heterologously expressed human TRPM5 in HEK-293 cells. TRPM5 displays characteristics of a calcium-activated, nonselective cation channel with a unitary conductance of 25 pS. TRPM5 is a monovalent-specific, nonselective cation channel that carries Na+, K+, and Cs+ ions equally well, but not Ca2+ ions. It is directly activated by [Ca2+]i at concentrations of 0.3-1 microM, whereas higher concentrations are inhibitory, resulting in a bell-shaped dose-response curve. It activates and deactivates rapidly even during sustained elevations in [Ca2+]i, thereby inducing a transient membrane depolarization. TRPM5 does not simply mirror levels of [Ca2+]i, but instead responds to the rate of change in [Ca2+]i in that it requires rapid changes in [Ca2+]i to generate significant whole-cell currents, whereas slow elevations in [Ca2+]i to equivalent levels are ineffective. Moreover, we demonstrate that TRPM5 is not limited to taste signal transduction, because we detect the presence of TRPM5 in a variety of tissues and we identify endogenous TRPM5-like currents in a pancreatic beta cell line. TRPM5 can be activated physiologically by inositol 1,4,5-trisphosphate-producing receptor agonists, and it may therefore couple intracellular Ca2+ release to electrical activity and subsequent cellular responses.

  9. Structural analysis and Miocene-to-Present tectonic evolution of a lithospheric-scale, transcurrent lineament: The Sciacca Fault (Sicilian Channel, Central Mediterranean Sea)

    Science.gov (United States)

    Fedorik, Jakub; Toscani, Giovanni; Lodolo, Emanuele; Civile, Dario; Bonini, Lorenzo; Seno, Silvio

    2018-01-01

    Seismo-stratigraphic and structural analysis of a large number of multichannel seismic reflection profiles acquired in the northern part of the Sicilian Channel allowed a 3-D reconstruction of a regional NS-trending transfer zone which displays a transcurrent tectonic regime, and that is of broad relevance for its seismotectonic and geodynamic implications. It is constituted of two major transcurrent faults delimiting a 30-km-wide, mostly undeformed basin. The western fault (Capo Granitola) does not show clear evidence of present-day tectonic activity, and toward the south it is connected with the volcanic area of the Graham Bank. The eastern fault (Sciacca) is structurally more complex, showing active deformation at the sea-floor, particularly evident along the Nerita Bank. The Sciacca Fault is constituted of a master and splay faults compatible with a right-lateral kinematics. Sciacca Fault is superimposed on an inherited weakness zone (a Mesozoic carbonate ramp), which borders to the east a 2.5-km-thick Plio-Quaternary basin, and that was reactivated during the Pliocene. A set of scaled claybox analogue models was carried out in order to better understand the tectonic processes that led to the structural setting displayed by seismic data. Tectonic structures and uplift/subsidence patterns generated by the models are compatible with the 3-D model obtained from seismic reflection profiles. The best fit between the tectonic setting deriving from the interpretation of seismic profiles and the analogue models was obtained considering a right-lateral movement for the Sciacca Fault. Nevertheless, the stress field in the study area derived from GPS measurements does not support the present-day modelled right-lateral kinematics along the Sciacca Fault. Moreover, seismic events along this fault show focal mechanisms with a left-lateral component. We ascribe the slip change along the Sciacca Fault, from a right-lateral transcurrent regime to the present-day left

  10. Experimental investigation on steady granular flows interacting with an obstacle down an inclined channel: study of the dead zone upstream from the obstacle. Application to interaction between dense snow avalanches and defence structures

    Directory of Open Access Journals (Sweden)

    T. Faug

    2002-01-01

    Full Text Available An experimental investigation with dry granular flows passing over an obstacle down a rough inclined channel has been performed. The aim is to improve our understanding of the interaction between dense snow avalanches and defence structures. Specific attention was directed to the study of the zone of influence upstream from the obstacle, linked to the formation of a dead zone. The dead zone length L was systematically measured as a function of the obstacle height H and the channel inclination θ, for several discharges. In a whole range of channel inclinations, all the data are shown to collapse into a single curve when properly scaled. The scaling is based on the introduction of a theoretical deposit length (depending on H, θ and the internal friction angle of the material, φ and a Froude number of the flow depending on the obstacle height.

  11. The non-selective monovalent cationic channels TRPM4 and TRPM5.

    Science.gov (United States)

    Guinamard, Romain; Sallé, Laurent; Simard, Christophe

    2011-01-01

    Transient Receptor Potential (TRP) proteins are non-selective cationic channels with a consistent Ca(2+)-permeability, except for TRPM4 and TRPM5 that are not permeable to this ion. However, Ca(2+) is a major regulator of their activity since both channels are activated by a rise in internal Ca(2+). Thus TRPM4 and TRPM5 are responsible for most of the Ca(2+)-activated non-selective cationic currents (NSC(Ca)) recorded in a large variety of tissues. Their activation induces cell-membrane depolarization that modifies the driving force for ions as well as activity of voltage gated channels and thereby strongly impacts cell physiology. In the last few years, the ubiquitously expressed TRPM4 channel has been implicated in insulin secretion, the immune response, constriction of cerebral arteries, the activity of inspiratory neurons and cardiac dysfunction. Conversely, TRPM5 whose expression is more restricted, has until now been mainly implicated in taste transduction.

  12. Learning the MMSE Channel Estimator

    OpenAIRE

    Neumann, David; Wiese, Thomas; Utschick, Wolfgang

    2017-01-01

    We present a method for estimating conditionally Gaussian random vectors with random covariance matrices, which uses techniques from the field of machine learning. Such models are typical in communication systems, where the covariance matrix of the channel vector depends on random parameters, e.g., angles of propagation paths. If the covariance matrices exhibit certain Toeplitz and shift-invariance structures, the complexity of the MMSE channel estimator can be reduced to O(M log M) floating ...

  13. Antimutagenic effect of Ge-132 on. gamma. -ray-induced mutations in Escherichia coli B/r WP2 trp/sup -/

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, H.; Kada, T. (National Inst. of Genetics, Mishima, Shizuoka (Japan))

    1982-12-01

    The effect of carboxyethylgermanium sesquioxide (Ge-132) over a concentration range of 0-30..mu..g/ml on ..gamma..-irradiated cells of Escherichia coli B/r WP2 trp (dose range 0-10 kR) has been examined. The mutation frequency (Trp/sup -/ ..-->.. Trp/sup +/) in absence of Ge-132 was approximately 1.1 x 10/sup -6/, whereas it became about 5.4 x 10/sup -8/ with soft agar supplementing 30 ..mu..g/ml of the metal compound. When similar experiments were made with unirradiated bacteria, the Ge-132 had little effect on the survival as well as on the mutability, indicating that Ge-132 itself is not a mutagen.

  14. Functional architecture of the CFTR chloride channel.

    Science.gov (United States)

    Linsdell, Paul

    2014-02-01

    Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ATP-binding cassette (ABC) family of membrane transport proteins. CFTR is unique among ABC proteins in that it functions not as an active transporter but as an ATP-gated Cl(-) channel. As an ion channel, the function of the CFTR transmembrane channel pore that mediates Cl(-) movement has been studied in great detail. On the other hand, only low resolution structural data is available on the transmembrane parts of the protein. The structure of the channel pore has, however, been modeled on the known structure of active transporter ABC proteins. Currently, significant barriers exist to building a unified view of CFTR pore structure and function. Reconciling functional data on the channel with indirect structural data based on other proteins with very different transport functions and substrates has proven problematic. This review summarizes current structural and functional models of the CFTR Cl(-) channel pore, including a comprehensive review of previous electrophysiological investigations of channel structure and function. In addition, functional data on the three-dimensional arrangement of pore-lining helices, as well as contemporary hypotheses concerning conformational changes in the pore that occur during channel opening and closing, are discussed. Important similarities and differences between different models of the pore highlight current gaps in our knowledge of CFTR structure and function. In order to fill these gaps, structural and functional models of the membrane-spanning pore need to become better integrated.

  15. Role of thermo TRPA1 and TRPV1 channels in heat, cold, and mechanical nociception of rats.

    Science.gov (United States)

    Nozadze, Ivliane; Tsiklauri, Nana; Gurtskaia, Gulnazi; Tsagareli, Merab G

    2016-02-01

    A sensitive response of the nervous system to changes in temperature is of predominant importance for homeotherms to maintain a stable body temperature. A number of temperature-sensitive transient receptor potential (TRP) ion channels have been studied as nociceptors that respond to extreme temperatures and harmful chemicals. Recent findings in the field of pain have established a family of six thermo-TRP channels (TRPA1, TRPM8, TRPV1, TRPV2, TRPV3, and TRPV4) that exhibit sensitivity to increases or decreases in temperature, as well as to chemical substances eliciting the respective hot or cold sensations. In this study, we used behavioral methods to investigate whether mustard oil (allyl isothiocyanate) and capsaicin affect the sensitivity to heat, innocuous and noxious cold, and mechanical stimuli in male rats. The results obtained indicate that TRPA1 and TRPV1 channels are clearly involved in pain reactions, and the TRPA1 agonist allyl isothiocyanate enhances the heat pain sensitivity, possibly by indirectly modulating TRPV1 channels coexpressed in nociceptors with TRPA1. Overall, our data support the role of thermosensitive TRPA1 and TRPV1 channels in pain modulation and show that these two thermoreceptor channels are in a synergistic and/or conditional relationship with noxious heat and cold cutaneous stimulation.

  16. Calcium-permeable ion channels in the kidney

    Science.gov (United States)

    Zhou, Yiming

    2016-01-01

    Calcium ions (Ca2+) are crucial for a variety of cellular functions. The extracellular and intracellular Ca2+ concentrations are thus tightly regulated to maintain Ca2+ homeostasis. The kidney, one of the major organs of the excretory system, regulates Ca2+ homeostasis by filtration and reabsorption. Approximately 60% of the Ca2+ in plasma is filtered, and 99% of that is reabsorbed by the kidney tubules. Ca2+ is also a critical signaling molecule in kidney development, in all kidney cellular functions, and in the emergence of kidney diseases. Recently, studies using genetic and molecular biological approaches have identified several Ca2+-permeable ion channel families as important regulators of Ca2+ homeostasis in kidney. These ion channel families include transient receptor potential channels (TRP), voltage-gated calcium channels, and others. In this review, we provide a brief and systematic summary of the expression, function, and pathological contribution for each of these Ca2+-permeable ion channels. Moreover, we discuss their potential as future therapeutic targets. PMID:27029425

  17. Trp-999 of beta-galactosidase (Escherichia coli) is a key residue for binding, catalysis, and synthesis of allolactose, the natural lac operon inducer.

    Science.gov (United States)

    Huber, Reuben E; Hakda, Shamina; Cheng, Calvino; Cupples, Claire G; Edwards, Robert A

    2003-02-18

    Trp-999 is a key residue for the action of beta-galactosidases (Escherichia coli). Several site specific substitutions (Phe, Gly, Tyr, Leu) for Trp-999 were made. Each substitution caused greatly decreased affinities for substrates and inhibitors that bind in the "shallow" mode, while the affinities of inhibitors that bind in the "deep" mode were not decreased nearly as much. This shows that Trp-999 is important for binding in the shallow mode. The residue is also very important for binding glucose to galactosyl-beta-galactosidase (as a transgalactosidic acceptor). Substitution greatly diminished the affinity for glucose. Substitutions also changed the activation thermodynamics and, subsequently, the rates of the catalytic reactions. The enthalpies of activation of the glycolytic bond cleavage step (galactosylation, k(2)) became less favorable while the entropies of activation of that step became more favorable as a result of the substitutions. Differing magnitudes of these enthalpic and entropic effects with ONPG as compared to PNPG caused the k(2) values for ONPG to decrease but to increase for PNPG. The enthalpies of activation for the common hydrolytic step (degalactosylation, k(3)) increased while the entropies of activation for this step did not change much. As a result, k(3) became small and rate determining for each substituted enzyme. The substitutions caused the rate constant (k(4)) of the transgalactosidic acceptor reactions with glucose (for the formation of allolactose) to become much larger and of the same order of magnitude as the normally large rate constants for transgalactosidic acceptor reactions with small alcohols. This is probably because glucose can approach with less restriction in the absence of Trp-999. However, since glucose binds very poorly to the galactosyl-beta-galactosidases with substitutions for Trp-999, the proportion of lactose molecules converted to allolactose is small. Thus, Trp-999 is also important for ensuring that an