WorldWideScience

Sample records for strongly bound myosin

  1. Bound states in a strong magnetic field

    International Nuclear Information System (INIS)

    Machado, C. S.; Navarra, F. S.; Noronha, J.; Oliveira, E. G.; Ferreira Filho, L. G.

    2013-01-01

    We expect a strong magnetic field to be produced in the perpendicular direction to the reaction plane, in a noncentral heavy-ion collision . The strength of the magnetic field is estimated to be eB∼m 2 π ∼ 0.02 GeV 2 at the RHIC and eB∼ 15m 2 π ∼ 0.3 GeV 2 at the LHC. We investigate the effects of the magnetic field on B 0 and D 0 mesons, focusing on the changes of the energy levels and of the mass of the bound states.

  2. Dependence of myosin-ATPase on structure bound creatine kinase in cardiac myfibrils from rainbow trout and freshwater turtle

    DEFF Research Database (Denmark)

    Haagensen, L.; Jensen, D.H.; Gesser, Hans

    2008-01-01

    The influence of myofibrillar creatine kinase on the myosin-ATPase activity was examined in cardiac ventricular myofibrils isolated from rainbow trout (Oncorhynchus mykiss) and freshwater turtle (Trachemys scripta). The ATPase rate was assessed by recording the rephosphorylation of ADP by the pyr......The influence of myofibrillar creatine kinase on the myosin-ATPase activity was examined in cardiac ventricular myofibrils isolated from rainbow trout (Oncorhynchus mykiss) and freshwater turtle (Trachemys scripta). The ATPase rate was assessed by recording the rephosphorylation of ADP...... activity twice or more for both trout and turtle. As examined for trout myofibrils, the ATPase activity was reduced about four times by inhibiting the activity of myofibril-bound creatine kinase with iodoacetamide and this reduction was only partially counteracted, when the creatine kinase activity...

  3. Bound states in strongly correlated magnetic and electronic systems

    International Nuclear Information System (INIS)

    Trebst, S.

    2002-02-01

    A novel strong coupling expansion method to calculate two-particle spectra of quantum lattice models is developed. The technique can be used to study bosonic and fermionic models and in principle it can be applied to systems in any dimension. A number of strongly correlated magnetic and electronic systems are examined including the two-leg spin-half Heisenberg ladder, the dimerized Heisenberg chain with a frustrating next-nearest neighbor interaction, coupled Heisenberg ladders, and the one-dimensional Kondo lattice model. In the various models distinct bound states are found below the two-particle continuum. Quantitative calculations of the dispersion, coherence length and binding energy of these bound states are used to describe spectroscopic experiments on (Ca,La) 14 Cu 24 O 41 and NaV 2 O 5 . (orig.)

  4. Influence of strong perturbations on wall-bounded flows

    Science.gov (United States)

    Buxton, O. R. H.; Ewenz Rocher, M.; Rodríguez-López, E.

    2018-01-01

    Single-point hot-wire measurements are made downstream of a series of spanwise repeating obstacles that are used to generate an artificially thick turbulent boundary layer. The measurements are made in the near field, in which the turbulent boundary layer is beginning to develop from the wall-bounded wakes of the obstacles. The recent paper of Rodríguez-López et al. [E. Rodríguez-López et al., Phys. Rev. Fluids 1, 074401 (2016), 10.1103/PhysRevFluids.1.074401] broadly categorized the mechanisms by which canonical turbulent boundary layers eventually develop from wall-bounded wakes into two distinct mechanisms, the wall-driven and wake-driven mechanisms. In the present work we attempt to identify the geometric parameters of tripping arrays that trigger these two mechanisms by examining the spectra of the streamwise velocity fluctuations and the intermittent outer region of the flow. Using a definition reliant upon the magnitude of the velocity fluctuations, an intermittency function is devised that can discriminate between turbulent and nonturbulent flow. These results are presented along with the spectra in order to try to ascertain which aspects of a trip's geometry are more likely to favor the wall-driven or wake-driven mechanism. The geometrical aspects of the trips tested are the aspect ratio, the total blockage, and the blockage at the wall. The results indicate that the presence, or not, of perforations is the most significant factor in affecting the flow downstream. The bleed of fluid through the perforations reenergizes the mean recirculation and leads to a narrower intermittent region with a more regular turbulent-nonturbulent interface. The near-wall turbulent motions are found to recover quickly downstream of all of the trips with a wall blockage of 50%, but a clear influence of the outer fluctuations, generated by the tip vortices of the trips, is observed in the near-wall region for the high total blockage trips. The trip with 100% wall blockage is

  5. In vitro actin motility velocity varies linearly with the number of myosin impellers.

    Science.gov (United States)

    Wang, Y; Burghardt, T P

    2017-03-15

    Cardiac myosin is the motor powering the heart. It moves actin with 3 step-size varieties generated by torque from the myosin heavy chain lever-arm rotation under the influence of myosin essential light chain whose N-terminal extension binds actin. Proposed mechanisms adapting myosin mechanochemical characteristics on the fly sometimes involve modulation of step-size selection probability via motor strain sensitivity. Strain following the power stroke, hypothetically imposed by the finite actin detachment rate 1/t on , is shown to have no effect on unloaded velocity when multiple myosins are simultaneously strongly actin bound in an in vitro motility assay. Actin filaments slide ∼2 native step-sizes while more than 1 myosin strongly binds actin probably ruling out an actin detachment limited model for imposing strain. It suggests that single myosin estimates for t on are too large, not applicable to the ensemble situation, or both. Parallel motility data quantitation involving instantaneous particle velocities (frame velocity) and actin filament track averaged velocities (track velocity) give an estimate of the random walk step-size, δ. Comparing δ for slow and fast motility components suggests the higher speed component has cardiac myosin upshifting to longer steps. Variable step-size characteristics imply cardiac myosin maintains a velocity dynamic range not involving strain. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. The Bekenstein bound in strongly coupled O(N) scalar field theory

    International Nuclear Information System (INIS)

    Magalhaes, T. Santos; Svaiter, N.F.; Menezes, G.

    2009-09-01

    We discuss the O(N) self-interacting scalar field theory, in the strong-coupling regime and also in the limit of large N. Considering that the system is in thermal equilibrium with a reservoir at temperature β -1 , we assume the presence of macroscopic boundaries conning the field in a hypercube of side L. Using the strong-coupling perturbative expansion, we generalize previous results, i.e., we obtain the renormalized mean energy E and entropy S for the system in rst order of the strong-coupling perturbative expansion, presenting an analytical proof that the specific entropy also satisfies in some situations a quantum bound. When considering the low temperature behavior of the specific entropy, the sign of the renormalized zero-point energy can invalidate this quantum bound. If the renormalized zero point-energy is a positive quantity, at intermediate temperatures and in the low temperature limit, there is a quantum bound. (author)

  7. The QCD mass gap and quark deconfinement scales as mass bounds in strong gravity

    Energy Technology Data Exchange (ETDEWEB)

    Burikham, Piyabut [Chulalongkorn University, High Energy Physics Theory Group, Department of Physics, Faculty of Science, Bangkok (Thailand); Harko, Tiberiu [Babes-Bolyai University, Department of Physics, Cluj-Napoca (Romania); University College London, Department of Mathematics, London (United Kingdom); Lake, Matthew J. [Sun Yat-Sen University, School of Physics, Guangzhou (China); Nanyang Technological University, School of Physical and Mathematical Sciences, Singapore (Singapore); Naresuan University, The Institute for Fundamental Study, ' ' The Tah Poe Academia Institute' ' , Phitsanulok (Thailand); Thailand Center of Excellence in Physics, Ministry of Education, Bangkok (Thailand)

    2017-11-15

    Though not a part of mainstream physics, Salam's theory of strong gravity remains a viable effective model for the description of strong interactions in the gauge singlet sector of QCD, capable of producing particle confinement and asymptotic freedom, but not of reproducing interactions involving SU(3) color charge. It may therefore be used to explore the stability and confinement of gauge singlet hadrons, though not to describe scattering processes that require color interactions. It is a two-tensor theory of both strong interactions and gravity, in which the strong tensor field is governed by equations formally identical to the Einstein equations, apart from the coupling parameter, which is of order 1 GeV{sup -1}. We revisit the strong gravity theory and investigate the strong gravity field equations in the presence of a mixing term which induces an effective strong cosmological constant, Λ{sub f}. This introduces a strong de Sitter radius for strongly interacting fermions, producing a confining bubble, which allows us to identify Λ{sub f} with the 'bag constant' of the MIT bag model, B ≅ 2 x 10{sup 14} g cm{sup -3}. Assuming a static, spherically symmetric geometry, we derive the strong gravity TOV equation, which describes the equilibrium properties of compact hadronic objects. From this, we determine the generalized Buchdahl inequalities for a strong gravity 'particle', giving rise to upper and lower bounds on the mass/radius ratio of stable, compact, strongly interacting objects. We show, explicitly, that the existence of the lower mass bound is induced by the presence of Λ{sub f}, producing a mass gap, and that the upper bound corresponds to a deconfinement phase transition. The physical implications of our results for holographic duality in the context of the AdS/QCD and dS/QCD correspondences are also discussed. (orig.)

  8. The QCD mass gap and quark deconfinement scales as mass bounds in strong gravity

    International Nuclear Information System (INIS)

    Burikham, Piyabut; Harko, Tiberiu; Lake, Matthew J.

    2017-01-01

    Though not a part of mainstream physics, Salam's theory of strong gravity remains a viable effective model for the description of strong interactions in the gauge singlet sector of QCD, capable of producing particle confinement and asymptotic freedom, but not of reproducing interactions involving SU(3) color charge. It may therefore be used to explore the stability and confinement of gauge singlet hadrons, though not to describe scattering processes that require color interactions. It is a two-tensor theory of both strong interactions and gravity, in which the strong tensor field is governed by equations formally identical to the Einstein equations, apart from the coupling parameter, which is of order 1 GeV -1 . We revisit the strong gravity theory and investigate the strong gravity field equations in the presence of a mixing term which induces an effective strong cosmological constant, Λ f . This introduces a strong de Sitter radius for strongly interacting fermions, producing a confining bubble, which allows us to identify Λ f with the 'bag constant' of the MIT bag model, B ≅ 2 x 10 14 g cm -3 . Assuming a static, spherically symmetric geometry, we derive the strong gravity TOV equation, which describes the equilibrium properties of compact hadronic objects. From this, we determine the generalized Buchdahl inequalities for a strong gravity 'particle', giving rise to upper and lower bounds on the mass/radius ratio of stable, compact, strongly interacting objects. We show, explicitly, that the existence of the lower mass bound is induced by the presence of Λ f , producing a mass gap, and that the upper bound corresponds to a deconfinement phase transition. The physical implications of our results for holographic duality in the context of the AdS/QCD and dS/QCD correspondences are also discussed. (orig.)

  9. Strong Convergence Bound of the Pareto Index Estimator under Right Censoring

    Directory of Open Access Journals (Sweden)

    Peng Zuoxiang

    2010-01-01

    Full Text Available Let be a sequence of positive independent and identically distributed random variables with common Pareto-type distribution function as , where represents a slowly varying function at infinity. In this note we study the strong convergence bound of a kind of right censored Pareto index estimator under second-order regularly varying conditions.

  10. Strong Convergence Bound of the Pareto Index Estimator under Right Censoring

    Directory of Open Access Journals (Sweden)

    Bao Tao

    2010-01-01

    Full Text Available Let {Xn,n≥1} be a sequence of positive independent and identically distributed random variables with common Pareto-type distribution function F(x=1−x−1/γlF(x as γ>0, where lF(x represents a slowly varying function at infinity. In this note we study the strong convergence bound of a kind of right censored Pareto index estimator under second-order regularly varying conditions.

  11. Bound-state β decay of a neutron in a strong magnetic field

    International Nuclear Information System (INIS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2005-01-01

    The β decay of a neutron into a bound (pe - ) state and an antineutrino in the presence of a strong uniform magnetic field (B > or approx. 10 13 G) is considered. The β decay process is treated within the framework of the standard model of weak interactions. A Bethe-Salpeter formalism is employed for description of the bound (pe - ) system in a strong magnetic field. For the field strengths 10 13 18 G the estimate for the ratio of the bound-state decay rate w b and the usual (continuum-state) decay rate w c is derived. It is found that in such strong magnetic fields w b /w c ∼0.1-0.4. This is in contrast to the field-free case, where w b /w c ≅4.2x10 -6 [J. N. Bahcall, Phys. Rev. 124, 495 (1961); L. L. Nemenov, Sov. J. Nucl. Phys. 15, 582 (1972); X. Song, J. Phys. G: Nucl. Phys. 13, 1023 (1987)]. The dependence of the ratio w b /w c on the magnetic field strength B exhibits a logarithmiclike behavior. The obtained results can be important for applications in astrophysics and cosmology

  12. A k-Bounded Symbolic Execution for Checking Strong Heap Properties of Open Systems

    DEFF Research Database (Denmark)

    Lee, Jooyong; Deng, Xianghua; Bogor, Robby

    2006-01-01

    This paper presents Kiasan, a bounded technique to reason about open systems based on a path sensitive, relatively sound and complete symbolic execution instead of the usual compositional reasoning through weakest precondition calculation that summarizes all execution paths. Kiasan is able to check...... strong heap properties, and it is fully automatic and flexible in terms of its cost and the guarantees it provides. It allows a user-adjustable mixed compositional/non-compositional reasoning and naturally produces error traces as fault evidence. We implemented Kiasan using the Bogor model checking...

  13. High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED.

    Science.gov (United States)

    Ullmann, Johannes; Andelkovic, Zoran; Brandau, Carsten; Dax, Andreas; Geithner, Wolfgang; Geppert, Christopher; Gorges, Christian; Hammen, Michael; Hannen, Volker; Kaufmann, Simon; König, Kristian; Litvinov, Yuri A; Lochmann, Matthias; Maaß, Bernhard; Meisner, Johann; Murböck, Tobias; Sánchez, Rodolfo; Schmidt, Matthias; Schmidt, Stefan; Steck, Markus; Stöhlker, Thomas; Thompson, Richard C; Trageser, Christian; Vollbrecht, Jonas; Weinheimer, Christian; Nörtershäuser, Wilfried

    2017-05-16

    Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209 Bi 82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron-nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209 Bi 82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction.

  14. Violation of the Holographic Viscosity Bound in a Strongly Coupled Anisotropic Plasma

    Science.gov (United States)

    Rebhan, Anton; Steineder, Dominik

    2012-01-01

    We study the conductivity and shear viscosity tensors of a strongly coupled N=4 super-Yang-Mills plasma which is kept anisotropic by a θ parameter that depends linearly on one of the spatial dimensions. Its holographic dual is given by an anisotropic axion-dilaton-gravity background and has recently been proposed by Mateos and Trancanelli as a model for the preequilibrium stage of quark-gluon plasma in heavy-ion collisions. By applying the membrane paradigm which we also check by numerical evaluation of Kubo formula and lowest lying quasinormal modes, we find that the shear viscosity purely transverse to the direction of anisotropy saturates the holographic viscosity bound, whereas longitudinal shear viscosities are smaller, providing the first such example not involving higher-derivative theories of gravity and, more importantly, with fully known gauge-gravity correspondence.

  15. Strongly bound excitons in monolayer PtS2 and PtSe2

    KAUST Repository

    Sajjad, M.

    2018-01-22

    Based on first-principles calculations, the structural, electronic, and optical properties of monolayers PtS2 and PtSe2 are investigated. The bond stiffnesses and elastic moduli are determined by means of the spring constants and strain-energy relations, respectively. Dynamic stability is confirmed by calculating the phonon spectra, which shows excellent agreement with experimental reports for the frequencies of the Raman-active modes. The Heyd-Scuseria-Ernzerhof functional results in electronic bandgaps of 2.66 eV for monolayer PtS2 and 1.74 eV for monolayer PtSe2. G0W0 calculations combined with the Bethe-Salpeter equation are used to predict the optical spectra and exciton binding energies (0.78 eV for monolayer PtS2 and 0.60 eV for monolayer PtSe2). It turns out that the excitons are strongly bound and therefore very stable against external perturbations.

  16. Strong solutions for the Navier-Stokes equations on bounded and unbounded domains with a moving boundary

    Directory of Open Access Journals (Sweden)

    Juergen Saal

    2007-02-01

    Full Text Available It is proved under mild regularity assumptions on the data that the Navier-Stokes equations in bounded and unbounded noncylindrical regions admit a unique local-in-time strong solution. The result is based on maximal regularity estimates for the in spatial regions with a moving boundary obtained in [16] and the contraction mapping principle.

  17. Azidoblebbistatin, a photoreactive myosin inhibitor

    Science.gov (United States)

    Képiró, Miklós; Várkuti, Boglárka H.; Bodor, Andrea; Hegyi, György; Drahos, László; Kovács, Mihály; Málnási-Csizmadia, András

    2012-01-01

    Photoreactive compounds are important tools in life sciences that allow precisely timed covalent crosslinking of ligands and targets. Using a unique technique we have synthesized azidoblebbistatin, which is a derivative of blebbistatin, the most widely used myosin inhibitor. Without UV irradiation azidoblebbistatin exhibits identical inhibitory properties to those of blebbistatin. Using UV irradiation, azidoblebbistatin can be covalently crosslinked to myosin, which greatly enhances its in vitro and in vivo effectiveness. Photo-crosslinking also eliminates limitations associated with the relatively low myosin affinity and water solubility of blebbistatin. The wavelength used for photo-crosslinking is not toxic for cells and tissues, which confers a great advantage in in vivo tests. Because the crosslink results in an irreversible association of the inhibitor to myosin and the irradiation eliminates the residual activity of unbound inhibitor molecules, azidoblebbistatin has a great potential to become a highly effective tool in both structural studies of actomyosin contractility and the investigation of cellular and physiological functions of myosin II. We used azidoblebbistatin to identify previously unknown low-affinity targets of the inhibitor (EC50 ≥ 50 μM) in Dictyostelium discoideum, while the strongest interactant was found to be myosin II (EC50 = 5 μM). Our results demonstrate that azidoblebbistatin, and potentially other azidated drugs, can become highly useful tools for the identification of strong- and weak-binding cellular targets and the determination of the apparent binding affinities in in vivo conditions. PMID:22647605

  18. Biochemical kinetic characterization of the Acanthamoeba myosin-I ATPase.

    Science.gov (United States)

    Ostap, E M; Pollard, T D

    1996-03-01

    Acanthamoeba myosin-IA and myosin-IB are single-headed molecular motors that may play an important role in membrane-based motility. To better define the types of motility that myosin-IA and myosin IB can support, we determined the rate constants for key steps on the myosin-I ATPase pathway using fluorescence stopped-flow, cold-chase, and rapid-quench techniques. We determined the rate constants for ATP binding, ATP hydrolysis, actomyosin-I dissociation, phosphate release, and ADP release. We also determined equilibrium constants for myosin-I binding to actin filaments, ADP binding to actomyosin-I, and ATP hydrolysis. These rate constants define an ATPase mechanism in which (a) ATP rapidly dissociates actomyosin-I, (b) the predominant steady-state intermediates are in a rapid equilibrium between actin-bound and free states, (c) phosphate release is rate limiting and regulated by heavy-chain phosphorylation, and (d) ADP release is fast. Thus, during steady-state ATP hydrolysis, myosin-I is weakly bound to the actin filament like skeletal muscle myosin-II and unlike the microtubule-based motor kinesin. Therefore, for myosin-I to support processive motility or cortical contraction, multiple myosin-I molecules must be specifically localized to a small region on a membrane or in the actin-rich cell cortex. This conclusion has important implications for the regulation of myosin-I via localization through the unique myosin-I tails. This is the first complete transient kinetic characterization of a member of the myosin superfamily, other than myosin-II, providing the opportunity to obtain insights about the evolution of all myosin isoforms.

  19. Strong Coupling and Bounds on the Spin-2 Mass in Massive Gravity

    Science.gov (United States)

    Burrage, Clare; Kaloper, Nemanja; Padilla, Antonio

    2013-07-01

    The de Rham-Gabadadze-Tolley theory of a single massive spin-2 field has a cutoff much below its Planck scale because the extra modes from the massive spin-2 multiplet involve higher derivative self-interactions, controlled by a scale convoluted from its mass. Generically, these correct the propagator by environmental effects. The resulting effective cutoff depends on the environmental parameters and the spin-2 “graviton” mass. Requiring the theory to be perturbative down to O(1)mm, we derive bounds on the mass, corresponding to ≳O(1)meV for the generic case, assuming the coupling to be given by the standard Newton’s constant, and somewhat weaker bounds in cases with fine-tuning. Thus, the theory of a single massive spin-2 can really only be viewed as a theory describing the full nonlinear propagation of a massive spin-2 field on a fixed background and not as an approximation to general relativity.

  20. Strongly regular family of boundary-fitted tetrahedral meshes of bounded C^2 domains

    Czech Academy of Sciences Publication Activity Database

    Hošek, Radim

    2016-01-01

    Roč. 61, č. 3 (2016), s. 233-251 ISSN 0862-7940 EU Projects: European Commission(XE) 320078 - MATHEF Institutional support: RVO:67985840 Keywords : boundary fitted mesh * strongly regular family * Sommerville tetrahedron Subject RIV: BA - General Mathematics Impact factor: 0.618, year: 2016 http://hdl.handle.net/10338.dmlcz/145699

  1. Direct Observation of Phosphate Inhibiting the Force-Generating Capacity of a Miniensemble of Myosin Molecules

    Science.gov (United States)

    Debold, Edward P.; Walcott, Sam; Woodward, Mike; Turner, Matthew A.

    2013-01-01

    Elevated levels of phosphate (Pi) reduce isometric force, providing support for the notion that the release of Pi from myosin is closely associated with the generation of muscular force. Pi is thought to rebind to actomyosin in an ADP-bound state and reverse the force-generating steps, including the rotation of the lever arm (i.e., the powerstroke). Despite extensive study, this mechanism remains controversial, in part because it fails to explain the effects of Pi on isometric ATPase and unloaded shortening velocity. To gain new insight into this process, we determined the effect of Pi on the force-generating capacity of a small ensemble of myosin (∼12 myosin heads) using a three-bead laser trap assay. In the absence of Pi, myosin pulled the actin filament out of the laser trap an average distance of 54 ± 4 nm, translating into an average peak force of 1.2 pN. By contrast, in the presence of 30 mM Pi, myosin generated only enough force to displace the actin filament by 13 ± 1 nm, generating just 0.2 pN of force. The elevated Pi also caused a >65% reduction in binding-event lifetime, suggesting that Pi induces premature detachment from a strongly bound state. Definitive evidence of a Pi-induced powerstroke reversal was not observed, therefore we determined if a branched kinetic model in which Pi induces detachment from a strongly bound, postpowerstroke state could explain these observations. The model was able to accurately reproduce not only the data presented here, but also the effects of Pi on both isometric ATPase in muscle fibers and actin filament velocity in a motility assay. The ability of the model to capture the findings presented here as well as previous findings suggests that Pi-induced inhibition of force may proceed along a kinetic pathway different from that of force generation. PMID:24268149

  2. Acceleration of the sliding movement of actin filaments with the use of a non-motile mutant myosin in in vitro motility assays driven by skeletal muscle heavy meromyosin.

    Directory of Open Access Journals (Sweden)

    Kohei Iwase

    Full Text Available We examined the movement of an actin filament sliding on a mixture of normal and genetically modified myosin molecules that were attached to a glass surface. For this purpose, we used a Dictyostelium G680V mutant myosin II whose release rates of Pi and ADP were highly suppressed relative to normal myosin, leading to a significantly extended life-time of the strongly bound state with actin and virtually no motility. When the mixing ratio of G680V mutant myosin II to skeletal muscle HMM (heavy myosin was 0.01%, the actin filaments moved intermittently. When they moved, their sliding velocities were about two-fold faster than the velocity of skeletal HMM alone. Furthermore, sliding movements were also faster when the actin filaments were allowed to slide on skeletal muscle HMM-coated glass surfaces in the motility buffer solution containing G680V HMM. In this case no intermittent movement was observed. When the actin filaments used were copolymerized with a fusion protein consisting of Dictyostelium actin and Dictyostelium G680V myosin II motor domain, similar faster sliding movements were observed on skeletal muscle HMM-coated surfaces. The filament sliding velocities were about two-fold greater than the velocities of normal actin filaments. We found that the velocity of actin filaments sliding on skeletal muscle myosin molecules increased in the presence of a non-motile G680V mutant myosin motor.

  3. A Drosophila model of dominant inclusion body myopathy type 3 shows diminished myosin kinetics that reduce muscle power and yield myofibrillar defects.

    Science.gov (United States)

    Suggs, Jennifer A; Melkani, Girish C; Glasheen, Bernadette M; Detor, Mia M; Melkani, Anju; Marsan, Nathan P; Swank, Douglas M; Bernstein, Sanford I

    2017-06-01

    Individuals with inclusion body myopathy type 3 (IBM3) display congenital joint contractures with early-onset muscle weakness that becomes more severe in adulthood. The disease arises from an autosomal dominant point mutation causing an E706K substitution in myosin heavy chain type IIa. We have previously expressed the corresponding myosin mutation (E701K) in homozygous Drosophila indirect flight muscles and recapitulated the myofibrillar degeneration and inclusion bodies observed in the human disease. We have also found that purified E701K myosin has dramatically reduced actin-sliding velocity and ATPase levels. Since IBM3 is a dominant condition, we now examine the disease state in heterozygote Drosophila in order to gain a mechanistic understanding of E701K pathogenicity. Myosin ATPase activities in heterozygotes suggest that approximately equimolar levels of myosin accumulate from each allele. In vitro actin sliding velocity rates for myosin isolated from the heterozygotes were lower than the control, but higher than for the pure mutant isoform. Although sarcomeric ultrastructure was nearly wild type in young adults, mechanical analysis of skinned indirect flight muscle fibers revealed a 59% decrease in maximum oscillatory power generation and an approximately 20% reduction in the frequency at which maximum power was produced. Rate constant analyses suggest a decrease in the rate of myosin attachment to actin, with myosin spending decreased time in the strongly bound state. These mechanical alterations result in a one-third decrease in wing beat frequency and marginal flight ability. With aging, muscle ultrastructure and function progressively declined. Aged myofibrils showed Z-line streaming, consistent with the human heterozygote phenotype. Based upon the mechanical studies, we hypothesize that the mutation decreases the probability of the power stroke occurring and/or alters the degree of movement of the myosin lever arm, resulting in decreased in vitro

  4. A Drosophila model of dominant inclusion body myopathy type 3 shows diminished myosin kinetics that reduce muscle power and yield myofibrillar defects

    Directory of Open Access Journals (Sweden)

    Jennifer A. Suggs

    2017-06-01

    Full Text Available Individuals with inclusion body myopathy type 3 (IBM3 display congenital joint contractures with early-onset muscle weakness that becomes more severe in adulthood. The disease arises from an autosomal dominant point mutation causing an E706K substitution in myosin heavy chain type IIa. We have previously expressed the corresponding myosin mutation (E701K in homozygous Drosophila indirect flight muscles and recapitulated the myofibrillar degeneration and inclusion bodies observed in the human disease. We have also found that purified E701K myosin has dramatically reduced actin-sliding velocity and ATPase levels. Since IBM3 is a dominant condition, we now examine the disease state in heterozygote Drosophila in order to gain a mechanistic understanding of E701K pathogenicity. Myosin ATPase activities in heterozygotes suggest that approximately equimolar levels of myosin accumulate from each allele. In vitro actin sliding velocity rates for myosin isolated from the heterozygotes were lower than the control, but higher than for the pure mutant isoform. Although sarcomeric ultrastructure was nearly wild type in young adults, mechanical analysis of skinned indirect flight muscle fibers revealed a 59% decrease in maximum oscillatory power generation and an approximately 20% reduction in the frequency at which maximum power was produced. Rate constant analyses suggest a decrease in the rate of myosin attachment to actin, with myosin spending decreased time in the strongly bound state. These mechanical alterations result in a one-third decrease in wing beat frequency and marginal flight ability. With aging, muscle ultrastructure and function progressively declined. Aged myofibrils showed Z-line streaming, consistent with the human heterozygote phenotype. Based upon the mechanical studies, we hypothesize that the mutation decreases the probability of the power stroke occurring and/or alters the degree of movement of the myosin lever arm, resulting in

  5. Structural Characterization of the Binding of Myosin·ADP·Pi to Actin in Permeabilized Rabbit Psoas Muscle

    Science.gov (United States)

    Xu, Sengen; Gu, Jin; Belknap, Betty; White, Howard; Yu, Leepo C.

    2006-01-01

    When myosin is attached to actin in a muscle cell, various structures in the filaments are formed. The two strongly bound states (A·M·ADP and A·M) and the weakly bound A·M·ATP states are reasonably well understood. The orientation of the strongly bound myosin heads is uniform (“stereospecific” attachment), and the attached heads exhibit little spatial fluctuation. In the prehydrolysis weakly bound A·M·ATP state, the orientations of the attached myosin heads assume a wide range of azimuthal and axial angles, indicating considerable flexibility in the myosin head. The structure of the other weakly bound state, A·M·ADP·Pi, however, is poorly understood. This state is thought to be the critical pre-power-stroke state, poised to make the transition to the strongly binding, force-generating states, and hence it is of particular interest for understanding the mechanism of contraction. However, because of the low affinity between myosin and actin in the A·M·ADP·Pi state, the structure of this state has eluded determination both in isolated form and in muscle cells. With the knowledge recently gained in the structures of the weakly binding M·ATP, M·ADP·Pi states and the weakly attached A·M·ATP state in muscle fibers, it is now feasible to delineate the in vivo structure of the attached state of A·M·ADP·Pi. The series of experiments presented in this article were carried out under relaxing conditions at 25°C, where ∼95% of the myosin heads in the skinned rabbit psoas muscle contain the hydrolysis products. The affinity for actin is enhanced by adding polyethylene glycol (PEG) or by lowering the ionic strength in the bathing solution. Solution kinetics and binding constants were determined in the presence and in the absence of PEG. When the binding between actin and myosin was increased, both the myosin layer lines and the actin layer lines increased in intensity, but the intensity profiles did not change. The configuration (mode) of attachment in

  6. Structural characterization of the binding of Myosin*ADP*Pi to actin in permeabilized rabbit psoas muscle.

    Science.gov (United States)

    Xu, Sengen; Gu, Jin; Belknap, Betty; White, Howard; Yu, Leepo C

    2006-11-01

    When myosin is attached to actin in a muscle cell, various structures in the filaments are formed. The two strongly bound states (A*M*ADP and A*M) and the weakly bound A*M*ATP states are reasonably well understood. The orientation of the strongly bound myosin heads is uniform ("stereospecific" attachment), and the attached heads exhibit little spatial fluctuation. In the prehydrolysis weakly bound A*M*ATP state, the orientations of the attached myosin heads assume a wide range of azimuthal and axial angles, indicating considerable flexibility in the myosin head. The structure of the other weakly bound state, A*M*ADP*P(i), however, is poorly understood. This state is thought to be the critical pre-power-stroke state, poised to make the transition to the strongly binding, force-generating states, and hence it is of particular interest for understanding the mechanism of contraction. However, because of the low affinity between myosin and actin in the A*M*ADP*P(i) state, the structure of this state has eluded determination both in isolated form and in muscle cells. With the knowledge recently gained in the structures of the weakly binding M*ATP, M*ADP*P(i) states and the weakly attached A*M*ATP state in muscle fibers, it is now feasible to delineate the in vivo structure of the attached state of A*M*ADP*P(i). The series of experiments presented in this article were carried out under relaxing conditions at 25 degrees C, where approximately 95% of the myosin heads in the skinned rabbit psoas muscle contain the hydrolysis products. The affinity for actin is enhanced by adding polyethylene glycol (PEG) or by lowering the ionic strength in the bathing solution. Solution kinetics and binding constants were determined in the presence and in the absence of PEG. When the binding between actin and myosin was increased, both the myosin layer lines and the actin layer lines increased in intensity, but the intensity profiles did not change. The configuration (mode) of attachment in

  7. Structural Characterization of the Binding of Myosin*ADP*Pi to Actin in Permeabilized Rabbit Psoas Muscle

    Energy Technology Data Exchange (ETDEWEB)

    Xu,S.; Gu, J.; Belknap, B.; White, H.; Yu, L.

    2006-01-01

    When myosin is attached to actin in a muscle cell, various structures in the filaments are formed. The two strongly bound states (A{center_dot}M{center_dot}ADP and A{center_dot}M) and the weakly bound A{center_dot}M{center_dot}ATP states are reasonably well understood. The orientation of the strongly bound myosin heads is uniform ('stereospecific' attachment), and the attached heads exhibit little spatial fluctuation. In the prehydrolysis weakly bound A{center_dot}M{center_dot}ATP state, the orientations of the attached myosin heads assume a wide range of azimuthal and axial angles, indicating considerable flexibility in the myosin head. The structure of the other weakly bound state, A{center_dot}M{center_dot}ADP{center_dot}P{sub i}, however, is poorly understood. This state is thought to be the critical pre-power-stroke state, poised to make the transition to the strongly binding, force-generating states, and hence it is of particular interest for understanding the mechanism of contraction. However, because of the low affinity between myosin and actin in the A{center_dot}M{center_dot}ADP{center_dot}P{sub i} state, the structure of this state has eluded determination both in isolated form and in muscle cells. With the knowledge recently gained in the structures of the weakly binding M{center_dot}ATP, M{center_dot}ADP{center_dot}P{sub i} states and the weakly attached A{center_dot}M{center_dot}ATP state in muscle fibers, it is now feasible to delineate the in vivo structure of the attached state of A{center_dot}M{center_dot}ADP{center_dot}P{sub i}. The series of experiments presented in this article were carried out under relaxing conditions at 25{sup o}C, where {approx}95% of the myosin heads in the skinned rabbit psoas muscle contain the hydrolysis products. The affinity for actin is enhanced by adding polyethylene glycol (PEG) or by lowering the ionic strength in the bathing solution. Solution kinetics and binding constants were determined in the

  8. Cargo recognition and cargo-mediated regulation of unconventional myosins.

    Science.gov (United States)

    Lu, Qing; Li, Jianchao; Zhang, Mingjie

    2014-10-21

    in determining the motor properties. Dab2, an adaptor protein linking endocytic vesicles with actin-filament-bound myosin-VI, can induce the motor to form a transport competent dimer. Such a cargo-mediated dimerization mechanism has also been observed in other myosins including myosin-V and myosin-VIIa. The tail domains of myosins are very diverse both in their lengths and protein domain compositions and thus enable motors to engage a broad range of different cellular cargoes. Remarkably, the cargo binding tail of one myosin alone often can bind to multiple distinct target proteins. A series of atomic structures of myosin-V/cargo complexes solved recently reveals that the globular cargo binding tail of the motor contains a number of nonoverlapping target recognition sites for binding to its cargoes including melanophilin, vesicle adaptors RILPL2, and vesicle-bound GTPase Rab11. The structures of the MyTH4-FERM tandems from myosin-VIIa and myosin-X in complex with their respective targets reveal that MyTH4 and FERM domains extensively interact with each other forming structural and functional supramodules in both motors and demonstrate that the structurally similar MyTH4-FERM tandems of the two motors display totally different target binding modes. These structural studies have also shed light on why numerous mutations found in these myosins can cause devastating human diseases such as deafness and blindness, intellectual disabilities, immune disorders, and diabetes.

  9. Thermal unfolding of Acanthamoeba myosin II and skeletal muscle myosin.

    Science.gov (United States)

    Zolkiewski, M; Redowicz, M J; Korn, E D; Ginsburg, A

    1996-04-16

    Studies on the thermal unfolding of monomeric Acanthamoeba myosin II and other myosins, in particular skeletal muscle myosin, using differential scanning calorimetry (DSC) are reviewed. The unfolding transitions for intact myosin or its head fragment are irreversible, whereas those of the rod part and its fragments are completely reversible. Acanthamoeba myosin II unfolds with a high degree of cooperativity from ca. 40-45 degrees C at pH 7.5 in 0.6 M KCl, producing a single, sharp endotherm in DSC. In contrast, thermal transitions of rabbit skeletal muscle myosin occur over a broader temperature range (ca. 40-60 degrees C) under the same conditions. The DSC studies on the unfolding of the myosin rod and its fragments allow identification of cooperative domains, each of which unfolds according to a two-state mechanism. Also, DSC data show the effect of the nucleotide-induced conformational changes in the myosin head on the protein stability.

  10. Application of bounding spectra to seismic design of piping based on the performance of above ground piping in power plants subjected to strong motion earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, J.D. [Stevenson and Associates, Cleveland, OH (United States)

    1995-02-01

    This report extends the potential application of Bounding Spectra evaluation procedures, developed as part of the A-46 Unresolved Safety Issue applicable to seismic verification of in-situ electrical and mechanical equipment, to in-situ safety related piping in nuclear power plants. The report presents a summary of earthquake experience data which define the behavior of typical U.S. power plant piping subject to strong motion earthquakes. The report defines those piping system caveats which would assure the seismic adequacy of the piping systems which meet those caveats and whose seismic demand are within the bounding spectra input. Based on the observed behavior of piping in strong motion earthquakes, the report describes the capabilities of the piping system to carry seismic loads as a function of the type of connection (i.e. threaded versus welded). This report also discusses in some detail the basic causes and mechanisms for earthquake damages and failures to power plant piping systems.

  11. Application of bounding spectra to seismic design of piping based on the performance of above ground piping in power plants subjected to strong motion earthquakes

    International Nuclear Information System (INIS)

    Stevenson, J.D.

    1995-02-01

    This report extends the potential application of Bounding Spectra evaluation procedures, developed as part of the A-46 Unresolved Safety Issue applicable to seismic verification of in-situ electrical and mechanical equipment, to in-situ safety related piping in nuclear power plants. The report presents a summary of earthquake experience data which define the behavior of typical U.S. power plant piping subject to strong motion earthquakes. The report defines those piping system caveats which would assure the seismic adequacy of the piping systems which meet those caveats and whose seismic demand are within the bounding spectra input. Based on the observed behavior of piping in strong motion earthquakes, the report describes the capabilities of the piping system to carry seismic loads as a function of the type of connection (i.e. threaded versus welded). This report also discusses in some detail the basic causes and mechanisms for earthquake damages and failures to power plant piping systems

  12. Theory of atoms in strong, pulsed electromagnetic fields: 2, A free electron and a harmonically bound electron

    International Nuclear Information System (INIS)

    Multiple scale methods are used to treat several ingredients of the theory of atoms in strong electromagnetic fields. First, a focused electromagnetic field is expanded. Second, a classical electron is described giving the ponderomotive potential. Third, the quantum electron is treated in the WKB approximation. Fourth, the one dimensional quantum harmonic oscillator is solved; and last the one dimensional square well, showing the low intensity limit of the theory

  13. Differential localization of Acanthamoeba myosin I isoforms

    Science.gov (United States)

    1992-01-01

    Acanthamoeba myosins IA and IB were localized by immunofluorescence and immunoelectron microscopy in vegetative and phagocytosing cells and the total cell contents of myosins IA, IB, and IC were quantified by immunoprecipitation. The quantitative distributions of the three myosin I isoforms were then calculated from these data and the previously determined localization of myosin IC. Myosin IA occurs almost exclusively in the cytoplasm, where it accounts for approximately 50% of the total myosin I, in the cortex beneath phagocytic cups and in association with small cytoplasmic vesicles. Myosin IB is the predominant isoform associated with the plasma membrane, large vacuole membranes and phagocytic membranes and accounts for almost half of the total myosin I in the cytoplasm. Myosin IC accounts for a significant fraction of the total myosin I associated with the plasma membrane and large vacuole membranes and is the only myosin I isoform associated with the contractile vacuole membrane. These data suggest that myosin IA may function in cytoplasmic vesicle transport and myosin I-mediated cortical contraction, myosin IB in pseudopod extension and phagocytosis, and myosin IC in contractile vacuole function. In addition, endogenous and exogenously added myosins IA and IB appeared to be associated with the cytoplasmic surface of different subpopulations of purified plasma membranes implying that the different myosin I isoforms are targeted to specific membrane domains through a mechanism that involves more than the affinity of the myosins for anionic phospholipids. PMID:1447297

  14. Myosin repertoire expansion coincides with eukaryotic diversification in the Mesoproterozoic era.

    Science.gov (United States)

    Kollmar, Martin; Mühlhausen, Stefanie

    2017-09-04

    The last eukaryotic common ancestor already had an amazingly complex cell possessing genomic and cellular features such as spliceosomal introns, mitochondria, cilia-dependent motility, and a cytoskeleton together with several intracellular transport systems. In contrast to the microtubule-based dyneins and kinesins, the actin-filament associated myosins are considerably divergent in extant eukaryotes and a unifying picture of their evolution has not yet emerged. Here, we manually assembled and annotated 7852 myosins from 929 eukaryotes providing an unprecedented dense sequence and taxonomic sampling. For classification we complemented phylogenetic analyses with gene structure comparisons resulting in 79 distinct myosin classes. The intron pattern analysis and the taxonomic distribution of the classes suggest two myosins in the last eukaryotic common ancestor, a class-1 prototype and another myosin, which is most likely the ancestor of all other myosin classes. The sparse distribution of class-2 and class-4 myosins outside their major lineages contradicts their presence in the last eukaryotic common ancestor but instead strongly suggests early eukaryote-eukaryote horizontal gene transfer. By correlating the evolution of myosin diversity with the history of Earth we found that myosin innovation occurred in independent major "burst" events in the major eukaryotic lineages. Most myosin inventions happened in the Mesoproterozoic era. In the late Neoproterozoic era, a process of extensive independent myosin loss began simultaneously with further eukaryotic diversification. Since the Cambrian explosion, myosin repertoire expansion is driven by lineage- and species-specific gene and genome duplications leading to subfunctionalization and fine-tuning of myosin functions.

  15. NUCLEAR MYOSIN II REGULATES THE ASSEMBLY OF PREINITIATION COMPLEX FOR ICAM-1 GENE TRANSCRIPTION

    Science.gov (United States)

    Li, Qingjie; Sarna, Sushil K.

    2009-01-01

    Background and Aims Actin-myosin II motor converts chemical energy into force/motion in muscle and non-muscle cells. The phosphorylation of regulatory light chain (MLC20) is critical to the cytoplasmic functions of these motors. We do not know whether myosin II and actins in the nucleus function as motors to generate relative motion, such as that between RNA polymerase II holoenzyme and DNA, for assembly of the preinitiation complex. Methods The experiments were performed on primary cultures of human colonic circular smooth muscle cells (HCCSMCs) and rat colonic circular muscle strips. Results We show that myosin II and α- and β-actins are present in the nuclei of colonic smooth muscle cells. The nuclear myosin II is tethered to recognition sequence AGCTCC (−39/−34) in the ICAM-1 core promoter region. The actins are known to complex with RNA polymerase II and they are tethered to the nucleoskeleton. The dephosphorylation of MLC20 increases the transcription of ICAM-1, whereas its phosphorylation decreases it. Colonic inflammation suppresses nuclear MLCK, which increases the unphosphorylated form of nuclear MLC20, resulting in enhanced transcription of ICAM-1. Conclusions 1) Myosin II is a core transcription factor; 2) the phosphorylation/dephosphorylation of nuclear MLC20 results in the sliding of myosin and actin molecules past each other producing relative motion between the DNA bound to the myosin II and RNA polymerase II holoenzyme bound to actins and nucleoskeleton. PMID:19328794

  16. The nuclear magnetic moment of 208Bi and its relevance for a test of bound-state strong-field QED

    Science.gov (United States)

    Schmidt, S.; Billowes, J.; Bissell, M. L.; Blaum, K.; Garcia Ruiz, R. F.; Heylen, H.; Malbrunot-Ettenauer, S.; Neyens, G.; Nörtershäuser, W.; Plunien, G.; Sailer, S.; Shabaev, V. M.; Skripnikov, L. V.; Tupitsyn, I. I.; Volotka, A. V.; Yang, X. F.

    2018-04-01

    The hyperfine structure splitting in the 6p3 3/2 4S → 6p2 7 s 1/2 4P transition at 307 nm in atomic 208Bi was measured with collinear laser spectroscopy at ISOLDE, CERN. The hyperfine A and B factors of both states were determined with an order of magnitude improved accuracy. Based on these measurements, theoretical input for the hyperfine structure anomaly, and results from hyperfine measurements on hydrogen-like and lithium-like 209Bi80+,82+, the nuclear magnetic moment of 208Bi has been determined to μ (208Bi) = + 4.570 (10)μN. Using this value, the transition energy of the ground-state hyperfine splitting in hydrogen-like and lithium-like 208Bi80+,82+ and their specific difference of -67.491(5)(148) meV are predicted. This provides a means for an experimental confirmation of the cancellation of nuclear structure effects in the specific difference in order to exclude such contributions as the cause of the hyperfine puzzle, the recently reported 7-σ discrepancy between experiment and bound-state strong-field QED calculations of the specific difference in the hyperfine structure splitting of 209Bi80+,82+.

  17. An investigation of problematic solids in oil sands processing : separation and characterization of organic matter strongly bound to oil sands solids

    Energy Technology Data Exchange (ETDEWEB)

    McCracken, T.; Woods, J.R.; Kung, J.; Fu, D.; Kingston, D.; Kotlyar, L.S. [National Research Council of Canada, Ottawa, ON (Canada). Inst. for Chemical Process and Environmental Technology; Sparks, B.D. [V. Bede Technical Associates, Ottawa, ON (Canada)

    2009-07-01

    Some of the solid fractions in Athabasca oilsands are associated with strongly bound organic matter that is insoluble in toluene, a solvent commonly used to extract bitumen. The presence of toluene insoluble organic matter (TIOM) increases oil wettability of solids which may adversely affect the release of bitumen from the oilsands. Some of the solid material from the coking operation may be carried over to downstream operations where it can cause fouling. This study used supercritical fluid extraction with methanol to remove TIOM from oilsands after extraction of bitumen by toluene. The methanol extract (ME) is soluble in toluene and was analyzed. Results were compared with corresponding bitumen fractions prepared using a modified HPLC SARA separation technique. Number average molecular weights for the ME were similar to those for resins separated from bitumen. The study also showed that the number of alkyl substituents on aromatic ring systems and the lengths of paraffinic straight chains for resins and ME samples were similar, with only minor differences in terms of H/C atomic ratios and aromaticities. The ME was more polar than the resin and asphaltene fractions, which may explain the selective adsorption of this fraction. tabs., figs.

  18. Actin and myosin contribute to mammalian mitochondrial DNA maintenance

    Science.gov (United States)

    Reyes, A.; He, J.; Mao, C. C.; Bailey, L. J.; Di Re, M.; Sembongi, H.; Kazak, L.; Dzionek, K.; Holmes, J. B.; Cluett, T. J.; Harbour, M. E.; Fearnley, I. M.; Crouch, R. J.; Conti, M. A.; Adelstein, R. S.; Walker, J. E.; Holt, I. J.

    2011-01-01

    Mitochondrial DNA maintenance and segregation are dependent on the actin cytoskeleton in budding yeast. We found two cytoskeletal proteins among six proteins tightly associated with rat liver mitochondrial DNA: non-muscle myosin heavy chain IIA and β-actin. In human cells, transient gene silencing of MYH9 (encoding non-muscle myosin heavy chain IIA), or the closely related MYH10 gene (encoding non-muscle myosin heavy chain IIB), altered the topology and increased the copy number of mitochondrial DNA; and the latter effect was enhanced when both genes were targeted simultaneously. In contrast, genetic ablation of non-muscle myosin IIB was associated with a 60% decrease in mitochondrial DNA copy number in mouse embryonic fibroblasts, compared to control cells. Gene silencing of β-actin also affected mitochondrial DNA copy number and organization. Protease-protection experiments and iodixanol gradient analysis suggest some β-actin and non-muscle myosin heavy chain IIA reside within human mitochondria and confirm that they are associated with mitochondrial DNA. Collectively, these results strongly implicate the actomyosin cytoskeleton in mammalian mitochondrial DNA maintenance. PMID:21398640

  19. Heavy chain of Acanthamoeba myosine IB is a fusion of myosin-like and non-myosin-like sequences

    Energy Technology Data Exchange (ETDEWEB)

    Jung, G.; Korn, E.D.; Hammer, J.A. III

    1987-10-01

    Acanthamoeba castellanii myosins IA and IB demonstrate the catalytic properties of a myosin and can support analogues of contractile and motile activity in vitro, but their single, low molecular weight heavy chains, roughly globular shapes, and inabilities to self-assemble into filaments make them structurally atypical myosins. The authors present the complete amino acid sequence of the 128-kDa myosin IB heavy chain, which they deduced from the nucleotide sequence of the gene and which reveals that the polypeptide is a fusion of myosin-like and non-myosin-like sequences. Specifically, the amino-terminal approx. 76 kDa of amino acid sequence is highly similar to the globular head sequences of conventional myosins. By contrast, the remaining approx. 51 kDa of sequence shows no similarity to any portion of conventional myosin sequences, contains regions that are rich in glycine, proline, and alanine residues, and lacks the distinctive sequence characteristics of an ..cap alpha..-helical, coiled-coil structure. They conclude, therefore, that the protein is composed of a myosin globular head fused not to the typical coiled-coil rod-like myosin tail structure but rather to an unusual carboxyl-terminal domain. These results support the conclusion that filamentous myosin is not required for force generation and provide a further perspective on the structural requirements for myosin function. Finally, they find a striking conservation of intron/exon structure between this gene and a vertebrate muscle myosin gene. They discuss this observation in relation to the evolutionary origin of the myosin IB gene and the antiquity of myosin gene intron/exon structure.

  20. Heavy chain of Acanthamoeba myosine IB is a fusion of myosin-like and non-myosin-like sequences

    International Nuclear Information System (INIS)

    Jung, G.; Korn, E.D.; Hammer, J.A. III

    1987-01-01

    Acanthamoeba castellanii myosins IA and IB demonstrate the catalytic properties of a myosin and can support analogues of contractile and motile activity in vitro, but their single, low molecular weight heavy chains, roughly globular shapes, and inabilities to self-assemble into filaments make them structurally atypical myosins. The authors present the complete amino acid sequence of the 128-kDa myosin IB heavy chain, which they deduced from the nucleotide sequence of the gene and which reveals that the polypeptide is a fusion of myosin-like and non-myosin-like sequences. Specifically, the amino-terminal ∼ 76 kDa of amino acid sequence is highly similar to the globular head sequences of conventional myosins. By contrast, the remaining ∼ 51 kDa of sequence shows no similarity to any portion of conventional myosin sequences, contains regions that are rich in glycine, proline, and alanine residues, and lacks the distinctive sequence characteristics of an α-helical, coiled-coil structure. They conclude, therefore, that the protein is composed of a myosin globular head fused not to the typical coiled-coil rod-like myosin tail structure but rather to an unusual carboxyl-terminal domain. These results support the conclusion that filamentous myosin is not required for force generation and provide a further perspective on the structural requirements for myosin function. Finally, they find a striking conservation of intron/exon structure between this gene and a vertebrate muscle myosin gene. They discuss this observation in relation to the evolutionary origin of the myosin IB gene and the antiquity of myosin gene intron/exon structure

  1. Three-dimensional stochastic model of actin–myosin binding in the sarcomere lattice

    Energy Technology Data Exchange (ETDEWEB)

    Mijailovich, Srboljub M.; Kayser-Herold, Oliver; Stojanovic, Boban; Nedic, Djordje; Irving, Thomas C.; Geeves, MA (Harvard); (IIT); (U. Kent); (Kragujevac)

    2016-11-18

    The effect of molecule tethering in three-dimensional (3-D) space on bimolecular binding kinetics is rarely addressed and only occasionally incorporated into models of cell motility. The simplest system that can quantitatively determine this effect is the 3-D sarcomere lattice of the striated muscle, where tethered myosin in thick filaments can only bind to a relatively small number of available sites on the actin filament, positioned within a limited range of thermal movement of the myosin head. Here we implement spatially explicit actomyosin interactions into the multiscale Monte Carlo platform MUSICO, specifically defining how geometrical constraints on tethered myosins can modulate state transition rates in the actomyosin cycle. The simulations provide the distribution of myosin bound to sites on actin, ensure conservation of the number of interacting myosins and actin monomers, and most importantly, the departure in behavior of tethered myosin molecules from unconstrained myosin interactions with actin. In addition, MUSICO determines the number of cross-bridges in each actomyosin cycle state, the force and number of attached cross-bridges per myosin filament, the range of cross-bridge forces and accounts for energy consumption. At the macroscopic scale, MUSICO simulations show large differences in predicted force-velocity curves and in the response during early force recovery phase after a step change in length comparing to the two simplest mass action kinetic models. The origin of these differences is rooted in the different fluxes of myosin binding and corresponding instantaneous cross-bridge distributions and quantitatively reflects a major flaw of the mathematical description in all mass action kinetic models. Consequently, this new approach shows that accurate recapitulation of experimental data requires significantly different binding rates, number of actomyosin states, and cross-bridge elasticity than typically used in mass action kinetic models to

  2. Direct photoaffinity labeling by nucleotides of the apparent catalytic site on the heavy chains of smooth muscle and Acanthamoeba myosins

    Energy Technology Data Exchange (ETDEWEB)

    Maruta, H.; Korn, E.D.

    1981-01-10

    The heavy chains of Acanthamoeba myosins, IA, IB and II, turkey gizzard myosin, and rabbit skeletal muscle myosin subfragment-1 were specifically labeled by radioactive ATP, ADP, and UTP, each of which is a substrate or product of myosin ATPase activity, when irradiated with uv light at 0/sup 0/C. With UTP, as much as 0.45 mol/mol of Acanthamoeba myosin IA heavy chain and 1 mol/mol of turkey gizzard myosin heavy chain was incorporated. Evidence that the ligands were associated with the catalytic site included the observations that reaction occurred only with nucleotides that are substrates or products of the ATPase activity; that the reaction was blocked by pyrophosphate which is an inhibitor of the ATPase activity; that ATP was bound as ADP; and that label was probably restricted to a single peptide following limited subtilisin proteolysis of labeled Acanthamoeba myosin IA heavy chain and extensive cleavage with CNBr and trypsin of labeled turkey gizzard myosin heavy chain.

  3. Direct photoaffinity labeling by nucleotides of the apparent catalytic site on the heavy chains of smooth muscle and Acanthamoeba myosins

    International Nuclear Information System (INIS)

    Maruta, H.; Korn, E.D.

    1981-01-01

    The heavy chains of Acanthamoeba myosins, IA, IB and II, turkey gizzard myosin, and rabbit skeletal muscle myosin subfragment-1 were specifically labeled by radioactive ATP, ADP, and UTP, each of which is a substrate or product of myosin ATPase activity, when irradiated with uv light at 0 0 C. With UTP, as much as 0.45 mol/mol of Acanthamoeba myosin IA heavy chain and 1 mol/mol of turkey gizzard myosin heavy chain was incorporated. Evidence that the ligands were associated with the catalytic site included the observations that reaction occurred only with nucleotides that are substrates or products of the ATPase activity; that the reaction was blocked by pyrophosphate which is an inhibitor of the ATPase activity; that ATP was bound as ADP; and that label was probably restricted to a single peptide following limited subtilisin proteolysis of labeled Acanthamoeba myosin IA heavy chain and extensive cleavage with CNBr and trypsin of labeled turkey gizzard myosin heavy chain

  4. Myosin lever arm directs collective motion on cellular actin network.

    Science.gov (United States)

    Hariadi, Rizal F; Cale, Mario; Sivaramakrishnan, Sivaraj

    2014-03-18

    The molecular motor myosin teams up to drive muscle contraction, membrane traffic, and cell division in biological cells. Myosin function in cells emerges from the interaction of multiple motors tethered to a scaffold, with surrounding actin filaments organized into 3D networks. Despite the importance of myosin function, the influence of intermotor interactions on collective motion remains poorly understood. In this study, we used precisely engineered myosin assemblies to examine emergence in collective myosin movement. We report that tethering multiple myosin VI motors, but not myosin V motors, modifies their movement trajectories on keratocyte actin networks. Single myosin V and VI dimers display similar skewed trajectories, albeit in opposite directions, when traversing the keratocyte actin network. In contrast, tethering myosin VI motors, but not myosin V motors, progressively straightens the trajectories with increasing myosin number. Trajectory shape of multimotor scaffolds positively correlates with the stiffness of the myosin lever arm. Swapping the flexible myosin VI lever arm for the relatively rigid myosin V lever increases trajectory skewness, and vice versa. A simplified model of coupled motor movement demonstrates that the differences in flexural rigidity of the two myosin lever arms is sufficient to account for the differences in observed behavior of groups of myosin V and VI motors. In accordance with this model trajectory, shapes for scaffolds containing both myosin V and VI are dominated by the myosin with a stiffer lever arm. Our findings suggest that structural features unique to each myosin type may confer selective advantages in cellular functions.

  5. Evaluation of Acanthamoeba Myosin-IC as a Potential Therapeutic Target

    Science.gov (United States)

    Lorenzo-Morales, Jacob; López-Arencibia, Atteneri; Reyes-Batlle, María; Piñero, José E.; Valladares, Basilio; Maciver, Sutherland K.

    2014-01-01

    Members of the genus Acanthamoeba are facultative pathogens of humans, causing a sight-threatening keratitis and a fatal encephalitis. We have targeted myosin-IC by using small interfering RNA (siRNA) silencing as a therapeutic approach, since it is known that the function of this protein is vital for the amoeba. In this work, specific siRNAs against the Acanthamoeba myosin-IC gene were developed. Treated and control amoebae were cultured in growth and encystment media to evaluate the induced effects after myosin-IC gene knockdown, as we have anticipated that cyst formation may be impaired. The effects of myosin-IC gene silencing were inhibition of cyst formation, inhibition of completion of cytokinesis, inhibition of osmoregulation under osmotic stress conditions, and death of the amoebae. The finding that myosin-IC silencing caused incompletion of cytokinesis is in agreement with earlier suggestions that the protein plays a role in cell locomotion, which is necessary to pull daughter cells apart after mitosis in a process known as “traction-mediated cytokinesis”. We conclude that myosin-IC is a very promising potential drug target for the development of much-needed antiamoebal drugs and that it should be further exploited for Acanthamoeba therapy. PMID:24468784

  6. Myosin-driven transport network in plants.

    Science.gov (United States)

    Kurth, Elizabeth G; Peremyslov, Valera V; Turner, Hannah L; Makarova, Kira S; Iranzo, Jaime; Mekhedov, Sergei L; Koonin, Eugene V; Dolja, Valerian V

    2017-02-21

    We investigate the myosin XI-driven transport network in Arabidopsis using protein-protein interaction, subcellular localization, gene knockout, and bioinformatics analyses. The two major groups of nodes in this network are myosins XI and their membrane-anchored receptors (MyoB) that, together, drive endomembrane trafficking and cytoplasmic streaming in the plant cells. The network shows high node connectivity and is dominated by generalists, with a smaller fraction of more specialized myosins and receptors. We show that interaction with myosins and association with motile vesicles are common properties of the MyoB family receptors. We identify previously uncharacterized myosin-binding proteins, putative myosin adaptors that belong to two unrelated families, with four members each (MadA and MadB). Surprisingly, MadA1 localizes to the nucleus and is rapidly transported to the cytoplasm, suggesting the existence of myosin XI-driven nucleocytoplasmic trafficking. In contrast, MadA2 and MadA3, as well as MadB1, partition between the cytosolic pools of motile endomembrane vesicles that colocalize with myosin XI-K and diffuse material that does not. Gene knockout analysis shows that MadB1-4 contribute to polarized root hair growth, phenocopying myosins, whereas MadA1-4 are redundant for this process. Phylogenetic analysis reveals congruent evolutionary histories of the myosin XI, MyoB, MadA, and MadB families. All these gene families emerged in green algae and show concurrent expansions via serial duplication in flowering plants. Thus, the myosin XI transport network increased in complexity and robustness concomitantly with the land colonization by flowering plants and, by inference, could have been a major contributor to this process.

  7. Control of the initiation and termination of kinesin-1-driven transport by myosin-Ic and nonmuscle tropomyosin.

    Science.gov (United States)

    McIntosh, Betsy B; Holzbaur, Erika L F; Ostap, E Michael

    2015-02-16

    Intracellular transport is largely driven by processive microtubule- and actin-based molecular motors. Nonprocessive motors have also been localized to trafficking cargos, but their roles are not well understood. Myosin-Ic (Myo1c), a nonprocessive actin motor, functions in a variety of exocytic events, although the underlying mechanisms are not yet clear. To investigate the interplay between myosin-I and the canonical long-distance transport motor kinesin-1, we attached both motor types to lipid membrane-coated bead cargo, using an attachment strategy that allows motors to actively reorganize within the membrane in response to the local cytoskeletal environment. We compared the motility of kinesin-1-driven cargos in the absence and presence of Myo1c at engineered actin/microtubule intersections. We found that Myo1c significantly increases the frequency of kinesin-1-driven microtubule-based runs that begin at actin/microtubule intersections. Myo1c also regulates the termination of processive runs. Beads with both motors bound have a significantly higher probability of pausing at actin/microtubule intersections, remaining tethered for an average of 20 s, with some pauses lasting longer than 200 s. The actin-binding protein nonmuscle tropomyosin (Tm) provides spatially specific regulation of interactions between myosin motors and actin filaments in vivo; in the crossed-filament in vitro assay, we found that Tm2-actin abolishes Myo1c-specific effects on both run initiation and run termination. Together, these observations suggest Myo1c is important for the selective initiation and termination of kinesin-1-driven runs along microtubules at specific actin filament populations within the cell. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Conformational changes of myosin by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju-Woon; Yook, Hong-Sun; Lee, Kyong-Haeng; Kim, Jae-Hun; Kim, Woo-Jung; Byun, Myung-Woo E-mail: mwbyun@nanum.kaeri.re.kr

    2000-05-01

    Conformational and decompositional changes of bovine skeletal muscle myosin caused by gamma irradiation were studied for understanding the effects of irradiation treatment on myofibrillar proteins. Myosin solution and beef cuts were irradiated 0, 1, 3, 5 and 10 kGy. Competitive indirect enzyme linked immunosorbent assay (Ci-ELISA) showed that subunits of myosin were structurally modified with different patterns. Binding abilities of anti-myosin whole molecule and anti heavy meromyosin S-1 IgG, which were produced from rabbits, with irradiated myosin decreased in the same tendency depending upon the dose. Anti-light meromyosin IgG appeared to have the highest binding ability at 3 kGy. Irradiated beef cuts ({>=}5 kGy) could be identified by Ci-ELISA. Myosin solution became increasingly turbid with increasing dose. Hydrophobicity of myosin solution also increased by irradiation. Electrophoretic patterns showed that the myosin heavy chain disappeared and new bands were generated at higher molecular weight ranges. (author)

  9. Nuclear Actin and Myosins in Adenovirus Infection

    Science.gov (United States)

    Fuchsova, Beata; Serebryannyy, Leonid A.; de Lanerolle, Primal

    2015-01-01

    Adenovirus serotypes have been shown to cause drastic changes in nuclear organization, including the transcription machinery, during infection. This ability of adenovirus to subvert transcription in the host cell facilitates viral replication. Because nuclear actin and nuclear myosin I, myosin V and myosin VI have been implicated as direct regulators of transcription and important factors in the replication of other viruses, we sought to determine how nuclear actin and myosins are involved in adenovirus infection. We first confirmed reorganization of the host’s transcription machinery to viral replication centers. We found that nuclear actin also reorganizes to sites of transcription through the intermediate but not the advanced late phase of viral infection. Furthermore, nuclear myosin I localized with nuclear actin and sites of transcription in viral replication centers. Intriguingly, nuclear myosins V and VI, which also reorganized to viral replication centers, exhibited different localization patterns, suggesting specialized roles for these nuclear myosins. Finally, we assessed the role of actin in adenovirus infection and found both cytoplasmic and nuclear actin likely play roles in adenovirus infection and replication. Together our data suggest the involvement of actin and multiple myosins in the nuclear replication and late viral gene expression of adenovirus. PMID:26226218

  10. Effect of nucleotides on the orientation and mobility of myosin subfragment-1 in ghost muscle fiber.

    Science.gov (United States)

    Pronina, O E; Wrzosek, A; Dabrowska, R; Borovikov, Yu S

    2005-10-01

    Using polarization fluorimetry, the orientation and mobility of 1,5-IAEDANS specifically bound to Cys707 of myosin subfragment-1 (S1) were studied in ghost muscle tropomyosin-containing fibers in the absence and in the presence of MgADP, MgAMP-PNP, MgATPgammaS, or MgATP. Modeling of various intermediate states was accompanied by discrete changes in actomyosin orientation and mobility of fluorescent dye dipoles. This suggests multistep changes in the structural state of the myosin head during the ATPase cycle. Maximal differences in the probe orientation by 4 degrees and its mobility by 30% were found between actomyosin states in the presence of MgADP and MgATP. It is suggested that interaction of S1 with F-actin induces nucleotide-dependent rotation of the whole motor domain of the myosin head or only the dye-binding site and also change in the head mobility.

  11. Uniqueness of bounded observables

    Energy Technology Data Exchange (ETDEWEB)

    Navara, M. [Czech Technical Univ., Praha (Czech Republic). Dept. of Math.

    1995-09-01

    By an application of a new construction technique we construct a {sigma}-orthomodular lattice with a strongly order-determining set of states and two bounded observables whose expectations are equal at each state. This answers negatively the uniqueness problem for bounded observables, formulated by S. Gudder. (orig.).

  12. P-cadherin counteracts myosin II-B function: implications in melanoma progression

    Directory of Open Access Journals (Sweden)

    De Wever Olivier

    2010-09-01

    Full Text Available Abstract Background Malignant transformation of melanocytes is frequently attended by a switch in cadherin expression profile as shown for E- and N-cadherin. For P-cadherin, downregulation in metastasizing melanoma has been demonstrated, and over-expression of P-cadherin in melanoma cell lines has been shown to inhibit invasion. The strong invasive and metastatic nature of cutaneous melanoma implies a deregulated interplay between intercellular adhesion and migration-related molecules Results In this study we performed a microarray analysis to compare the mRNA expression profile of an invasive BLM melanoma cell line (BLM LIE and the non-invasive P-cadherin over-expression variant (BLM P-cad. Results indicate that nonmuscle myosin II-B is downregulated in BLM P-cad. Moreover, myosin II-B plays a major role in melanoma migration and invasiveness by retracting the tail during the migratory cycle, as shown by the localization of myosin II-B stress fibers relative to Golgi and the higher levels of phosphorylated myosin light chain. Analysis of P-cadherin and myosin II-B in nodular melanoma sections and in a panel of melanoma cell lines further confirmed that there is an inverse relationship between both molecules. Conclusions Therefore, we conclude that P-cadherin counteracts the expression and function of myosin II-B, resulting in the suppression of the invasive and migratory behaviour of BLM melanoma cells

  13. Electron tomography of cryofixed, isometrically contracting insect flight muscle reveals novel actin-myosin interactions.

    Science.gov (United States)

    Wu, Shenping; Liu, Jun; Reedy, Mary C; Tregear, Richard T; Winkler, Hanspeter; Franzini-Armstrong, Clara; Sasaki, Hiroyuki; Lucaveche, Carmen; Goldman, Yale E; Reedy, Michael K; Taylor, Kenneth A

    2010-09-09

    Isometric muscle contraction, where force is generated without muscle shortening, is a molecular traffic jam in which the number of actin-attached motors is maximized and all states of motor action are trapped with consequently high heterogeneity. This heterogeneity is a major limitation to deciphering myosin conformational changes in situ. We used multivariate data analysis to group repeat segments in electron tomograms of isometrically contracting insect flight muscle, mechanically monitored, rapidly frozen, freeze substituted, and thin sectioned. Improved resolution reveals the helical arrangement of F-actin subunits in the thin filament enabling an atomic model to be built into the thin filament density independent of the myosin. Actin-myosin attachments can now be assigned as weak or strong by their motor domain orientation relative to actin. Myosin attachments were quantified everywhere along the thin filament including troponin. Strong binding myosin attachments are found on only four F-actin subunits, the "target zone", situated exactly midway between successive troponin complexes. They show an axial lever arm range of 77°/12.9 nm. The lever arm azimuthal range of strong binding attachments has a highly skewed, 127° range compared with X-ray crystallographic structures. Two types of weak actin attachments are described. One type, found exclusively in the target zone, appears to represent pre-working-stroke intermediates. The other, which contacts tropomyosin rather than actin, is positioned M-ward of the target zone, i.e. the position toward which thin filaments slide during shortening. We present a model for the weak to strong transition in the myosin ATPase cycle that incorporates azimuthal movements of the motor domain on actin. Stress/strain in the S2 domain may explain azimuthal lever arm changes in the strong binding attachments. The results support previous conclusions that the weak attachments preceding force generation are very different from

  14. Electron tomography of cryofixed, isometrically contracting insect flight muscle reveals novel actin-myosin interactions.

    Directory of Open Access Journals (Sweden)

    Shenping Wu

    2010-09-01

    Full Text Available Isometric muscle contraction, where force is generated without muscle shortening, is a molecular traffic jam in which the number of actin-attached motors is maximized and all states of motor action are trapped with consequently high heterogeneity. This heterogeneity is a major limitation to deciphering myosin conformational changes in situ.We used multivariate data analysis to group repeat segments in electron tomograms of isometrically contracting insect flight muscle, mechanically monitored, rapidly frozen, freeze substituted, and thin sectioned. Improved resolution reveals the helical arrangement of F-actin subunits in the thin filament enabling an atomic model to be built into the thin filament density independent of the myosin. Actin-myosin attachments can now be assigned as weak or strong by their motor domain orientation relative to actin. Myosin attachments were quantified everywhere along the thin filament including troponin. Strong binding myosin attachments are found on only four F-actin subunits, the "target zone", situated exactly midway between successive troponin complexes. They show an axial lever arm range of 77°/12.9 nm. The lever arm azimuthal range of strong binding attachments has a highly skewed, 127° range compared with X-ray crystallographic structures. Two types of weak actin attachments are described. One type, found exclusively in the target zone, appears to represent pre-working-stroke intermediates. The other, which contacts tropomyosin rather than actin, is positioned M-ward of the target zone, i.e. the position toward which thin filaments slide during shortening.We present a model for the weak to strong transition in the myosin ATPase cycle that incorporates azimuthal movements of the motor domain on actin. Stress/strain in the S2 domain may explain azimuthal lever arm changes in the strong binding attachments. The results support previous conclusions that the weak attachments preceding force generation are very

  15. Electron Tomography of Cryofixed, Isometrically Contracting Insect Flight Muscle Reveals Novel Actin-Myosin Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Shenping; Liu, Jun; Reedy, Mary C.; Tregear, Richard T.; Winkler, Hanspeter; Franzini-Armstrong, Clara; Sasaki, Hiroyuki; Lucaveche, Carmen; Goldman, Yale E.; Reedy, Michael K.; Taylor, Kenneth A. (UPENN); (Duke); (MRCLMB); (FSU); (Jikei-Med)

    2010-10-22

    Isometric muscle contraction, where force is generated without muscle shortening, is a molecular traffic jam in which the number of actin-attached motors is maximized and all states of motor action are trapped with consequently high heterogeneity. This heterogeneity is a major limitation to deciphering myosin conformational changes in situ. We used multivariate data analysis to group repeat segments in electron tomograms of isometrically contracting insect flight muscle, mechanically monitored, rapidly frozen, freeze substituted, and thin sectioned. Improved resolution reveals the helical arrangement of F-actin subunits in the thin filament enabling an atomic model to be built into the thin filament density independent of the myosin. Actin-myosin attachments can now be assigned as weak or strong by their motor domain orientation relative to actin. Myosin attachments were quantified everywhere along the thin filament including troponin. Strong binding myosin attachments are found on only four F-actin subunits, the 'target zone', situated exactly midway between successive troponin complexes. They show an axial lever arm range of 77{sup o}/12.9 nm. The lever arm azimuthal range of strong binding attachments has a highly skewed, 127{sup o} range compared with X-ray crystallographic structures. Two types of weak actin attachments are described. One type, found exclusively in the target zone, appears to represent pre-working-stroke intermediates. The other, which contacts tropomyosin rather than actin, is positioned M-ward of the target zone, i.e. the position toward which thin filaments slide during shortening. We present a model for the weak to strong transition in the myosin ATPase cycle that incorporates azimuthal movements of the motor domain on actin. Stress/strain in the S2 domain may explain azimuthal lever arm changes in the strong binding attachments. The results support previous conclusions that the weak attachments preceding force generation are

  16. Crystal structure of the complex of carboxypeptidase A with a strongly bound phosphonate in a new crystalline form: comparison with structures of other complexes.

    Science.gov (United States)

    Kim, H; Lipscomb, W N

    1990-06-12

    O-[[(1R)-[[N-(Phenylmethoxycarbonyl)-L-alanyl]amino]ethyl] hydroxyphosphinyl]-L-3-phenyllacetate [ZAAP(O)F], an analogue of (benzyloxycarbonyl)-Ala-Ala-Phe or (benzyloxycarbonyl)-Ala-Ala-phenyllactate, binds to carboxypeptidase A with great affinity (Ki = 3 pM). Similar phosphonates have been shown to be transition-state analogues of the CPA-catalyzed hydrolysis [Hanson, J. E., Kaplan, A. P., & Bartlett, P. A. (1989) Biochemistry 28, 6294-6305]. In the present study, the structure of the complex of this phosphonate with carboxypeptidase A has been determined by X-ray crystallography to a resolution of 2.0 A. The complex crystallizes in the space group P2(1)2(1)2(1) with cell dimensions a = 61.9 A, b = 67.2 A, and c = 76.2 A. The structure of the complex was solved by molecular replacement. Refinement of the structure against 20,776 unique reflections between 10.0 and 2.0 A yields a crystallographic residual of 0.193, including 140 water molecules. The two phosphinyl oxygens of the inhibitor bind to the active-site zinc at 2.2 A on the electrophilic (Arg-127) side and 3.1 A on the nucleophilic (Glu-270) side. Various features of the binding mode of this phosphonate inhibitor are consistent with the hypothesis that carboxypeptidase A catalyzed hydrolysis proceeds through a general-base mechanism in which the carbonyl carbon of the substrate is attacked by Zn-hydroxyl (or Zn-water). An unexpected feature of the bound inhibitor, the cis carbamoyl ester bond at the benzyloxycarbonyl linkage to alanine, allows the benzyloxycarbonyl phenyl ring of the inhibitor to interact favorably with Tyr-198. This complex structure is compared with previous structures of carboxypeptidase A, including the complexes with the potato inhibitor, a hydrated keto methylene substrate analogue, and a phosphonamidate inhibitor. Comparisons are also made with the complexes of thermolysin with some phosphonamidate inhibitors.

  17. Kinetic mechanism of myosinV-S1 using a new fluorescent ATP analogue.

    Science.gov (United States)

    Forgacs, Eva; Cartwright, Suzanne; Kovács, Mihály; Sakamoto, Takeshi; Sellers, James R; Corrie, John E T; Webb, Martin R; White, Howard D

    2006-10-31

    We have used a new fluorescent ATP analogue, 3'-(7-diethylaminocoumarin-3-carbonylamino)-3'-deoxyadenosine-5'-triphosphate (deac-aminoATP), to study the ATP hydrolysis mechanism of the single headed myosinV-S1. Our study demonstrates that deac-aminoATP is an excellent substrate for these studies. Although the deac-amino nucleotides have a low quantum yield in free solution, there is a very large increase in fluorescence emission ( approximately 20-fold) upon binding to the myosinV active site. The fluorescence emission intensity is independent of the hydrolysis state of the nucleotide bound to myosinV-S1. The very good signal-to-noise ratio that is obtained with deac-amino nucleotides makes them excellent substrates for studying expressed proteins that can only be isolated in small quantities. The combination of the fast rate of binding and the favorable signal-to-noise ratio also allows deac-nucleotides to be used in chase experiments to determine the kinetics of ADP and Pi dissociation from actomyosin-ADP-Pi. Although phosphate dissociation from actomyosinV-ADP-Pi does not itself produce a fluorescence signal, it produces a lag in the signal for deac-aminoADP dissociation. The lag provides direct evidence that the principal pathway of product dissociation from actomyosinV-ADP-Pi is an ordered mechanism in which phosphate precedes ADP. Although the mechanism of hydrolysis of deac-aminoATP by (acto)myosinV-S1 is qualitatively similar to the ATP hydrolysis mechanism, there are significant differences in some of the rate constants. Deac-aminoATP binds 3-fold faster to myosinV-S1, and the rate of deac-aminoADP dissociation from actomyosinV-S1 is 20-fold slower. Deac-aminoATP supports motility by myosinV-HMM on actin at a rate consistent with the slower rate of deac-aminoADP dissociation.

  18. Myosin-V opposes microtubule-based cargo transport and drives directional motility on cortical actin.

    Science.gov (United States)

    Kapitein, Lukas C; van Bergeijk, Petra; Lipka, Joanna; Keijzer, Nanda; Wulf, Phebe S; Katrukha, Eugene A; Akhmanova, Anna; Hoogenraad, Casper C

    2013-05-06

    Intracellular transport is driven by motor proteins that either use microtubules or actin filaments as their tracks, but the interplay between these transport pathways is poorly understood. Whereas many microtubule-based motors are known to drive long-range transport, several actin-based motors have been proposed to function predominantly in cargo tethering. How these opposing activities are integrated on cargoes that contain both types of motors is unknown. Here we use inducible intracellular transport assays to show that acute recruitment of myosin-V to kinesin-propelled cargo reduces their motility near the cell periphery and enhances their localization at the actin-rich cell cortex. Myosin-V arrests rapid microtubule-based transport without the need for regulated auto- or other inhibition of kinesin motors. In addition, myosin-V, despite being an ineffective long-range transporter, can drive slow, medium-range (1-5 μm), point-to-point transport in cortical cell regions. Altogether, these data support a model in which myosin-V establishes local cortical delivery of kinesin-bound cargos through a combination of tethering and active transport. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Alternative S2 Hinge Regions of the Myosin Rod Affect Myofibrillar Structure and Myosin Kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Mark S.; Dambacher, Corey M.; Knowles, Aileen F.; Braddock, Joan M.; Farman, Gerrie P.; Irving, Thomas C.; Swank, Douglas M.; Bernstein, Sanford I.; Maughan, David W.; (RPI); (IIT); (SDSU); (Vermont)

    2009-07-01

    The subfragment 2/light meromyosin 'hinge' region has been proposed to significantly contribute to muscle contraction force and/or speed. Transgenic replacement of the endogenous fast muscle isovariant hinge A (exon 15a) in Drosophila melanogaster indirect flight muscle with the slow muscle hinge B (exon 15b) allows examination of the structural and functional changes when only this region of the myosin molecule is different. Hinge B was previously shown to increase myosin rod length, increase A-band and sarcomere length, and decrease flight performance compared to hinge A. We applied additional measures to these transgenic lines to further evaluate the consequences of modifying this hinge region. Structurally, the longer A-band and sarcomere lengths found in the hinge B myofibrils appear to be due to the longitudinal addition of myosin heads. Functionally, hinge B, although a significant distance from the myosin catalytic domain, alters myosin kinetics in a manner consistent with this region increasing myosin rod length. These structural and functional changes combine to decrease whole fly wing-beat frequency and flight performance. Our results indicate that this hinge region plays an important role in determining myosin kinetics and in regulating thick and thin filament lengths as well as sarcomere length.

  20. Shaking the myosin family tree: biochemical kinetics defines four types of myosin motor.

    Science.gov (United States)

    Bloemink, Marieke J; Geeves, Michael A

    2011-12-01

    Although all myosin motors follow the same basic cross-bridge cycle, they display a large variety in the rates of transition between different states in the cycle, allowing each myosin to be finely tuned for a specific task. Traditionally, myosins have been classified by sequence analysis into a large number of sub-families (∼35). Here we use a different method to classify the myosin family members which is based on biochemical and mechanical properties. The key properties that define the type of mechanical activity of the motor are duty ratio (defined as the fraction of the time myosin remains attached to actin during each cycle), thermodynamic coupling of actin and nucleotide binding to myosin and the degree of strain-sensitivity of the ADP release step. Based on these properties we propose to classify myosins into four different groups: (I) fast movers, (II) slow/efficient force holders, (III) strain sensors and (IV) gates. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Bounding the $\

    CERN Document Server

    Gutiérrez-Rodríguez, A

    2003-01-01

    A bound on the nu /sup tau / magnetic moment is calculated through the reaction e/sup +/e/sup -/ to nu nu gamma at the Z/sub 1/-pole, and in the framework of a left-right symmetric model at LEP energies. We find that the bound is almost independent of the mixing angle phi of the model in the allowed experimental range for this parameter. (31 refs).

  2. Smooth muscle myosin light chain kinase efficiently phosphorylates serine 15 of cardiac myosin regulatory light chain

    Energy Technology Data Exchange (ETDEWEB)

    Josephson, Matthew P.; Sikkink, Laura A. [Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905 (United States); Penheiter, Alan R. [Molecular Medicine Program, Mayo Clinic, Rochester, MN 55905 (United States); Burghardt, Thomas P., E-mail: burghardt@mayo.edu [Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905 (United States); Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905 (United States); Ajtai, Katalin [Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905 (United States)

    2011-12-16

    Highlights: Black-Right-Pointing-Pointer Cardiac myosin regulatory light chain (MYL2) is phosphorylated at S15. Black-Right-Pointing-Pointer Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase. Black-Right-Pointing-Pointer It is a widely believed that MYL2 is a poor substrate for smMLCK. Black-Right-Pointing-Pointer In fact, smMLCK efficiently and rapidly phosphorylates S15 in MYL2. Black-Right-Pointing-Pointer Phosphorylation kinetics measured by novel fluorescence method without radioactivity. -- Abstract: Specific phosphorylation of the human ventricular cardiac myosin regulatory light chain (MYL2) modifies the protein at S15. This modification affects MYL2 secondary structure and modulates the Ca{sup 2+} sensitivity of contraction in cardiac tissue. Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase prevalent in uterus and present in other contracting tissues including cardiac muscle. The recombinant 130 kDa (short) smMLCK phosphorylated S15 in MYL2 in vitro. Specific modification of S15 was verified using the direct detection of the phospho group on S15 with mass spectrometry. SmMLCK also specifically phosphorylated myosin regulatory light chain S15 in porcine ventricular myosin and chicken gizzard smooth muscle myosin (S20 in smooth muscle) but failed to phosphorylate the myosin regulatory light chain in rabbit skeletal myosin. Phosphorylation kinetics, measured using a novel fluorescence method eliminating the use of radioactive isotopes, indicates similar Michaelis-Menten V{sub max} and K{sub M} for regulatory light chain S15 phosphorylation rates in MYL2, porcine ventricular myosin, and chicken gizzard myosin. These data demonstrate that smMLCK is a specific and efficient kinase for the in vitro phosphorylation of MYL2, cardiac, and smooth muscle myosin. Whether smMLCK plays a role in cardiac muscle regulation or response to a disease causing stimulus is unclear but it should be considered a potentially significant

  3. Cell and molecular biology of the fastest myosins.

    Science.gov (United States)

    Higashi-Fujime, Sugie; Nakamura, Akio

    2009-01-01

    Chara myosin is a class XI plant myosin in green algae Chara corallina and responsible for fast cytoplasmic streaming. The Chara myosin exhibits the fastest sliding movement of F-actin at 60 mum/s as observed so far, 10-fold of the shortening speed of muscle. It has some distinct properties differing from those of muscle myosin. Although knowledge about Chara myosin is very limited at present, we have tried to elucidate functional bases of its characteristics by comparing with those of other myosins. In particular, we have built the putative atomic model of Chara myosin by using the homology-based modeling system and databases. Based on the putative structure of Chara myosin obtained, we have analyzed the relationship between structure and function of Chara myosin to understand its distinct properties from various aspects by referring to the accumulated knowledge on mechanochemical and structural properties of other classes of myosin, particularly animal and fungal myosin V. We will also discuss the functional significance of Chara myosin in a living cell.

  4. Preparation of human cardiac anti-myosin: a review

    International Nuclear Information System (INIS)

    Okada, H.; Souza, I.T.T.

    1990-01-01

    The present communication is a review of the physicochemical characterization and immunological properties of myosin isolated from the cardiac muscle, the production of monoclonal antibody anti-myosin, the radiolabeling of this antibody and its applications as radiopharmaceuticals to imaging myocardial infarcts. The classical example of radioimmunologic diagnosis of non malignant tissues is the detection of myocardial infarction by radiolabeled antibodies to myosin. (author)

  5. Functions of myosin motors tailored for parasitism

    DEFF Research Database (Denmark)

    Mueller, Christina; Graindorge, Arnault; Soldati-Favre, Dominique

    2017-01-01

    Myosin motors are one of the largest protein families in eukaryotes that exhibit divergent cellular functions. Their roles in protozoans, a diverse group of anciently diverged, single celled organisms with many prominent members known to be parasitic and to cause diseases in human and livestock......, are largely unknown. In the recent years many different approaches, among them whole genome sequencing, phylogenetic analyses and functional studies have increased our understanding on the distribution, protein architecture and function of unconventional myosin motors in protozoan parasites. In Apicomplexa...

  6. Auxotonic to isometric contraction transitioning in a beating heart causes myosin step-size to down shift.

    Directory of Open Access Journals (Sweden)

    Thomas P Burghardt

    Full Text Available Myosin motors in cardiac ventriculum convert ATP free energy to the work of moving blood volume under pressure. The actin bound motor cyclically rotates its lever-arm/light-chain complex linking motor generated torque to the myosin filament backbone and translating actin against resisting force. Previous research showed that the unloaded in vitro motor is described with high precision by single molecule mechanical characteristics including unitary step-sizes of approximately 3, 5, and 8 nm and their relative step-frequencies of approximately 13, 50, and 37%. The 3 and 8 nm unitary step-sizes are dependent on myosin essential light chain (ELC N-terminus actin binding. Step-size and step-frequency quantitation specifies in vitro motor function including duty-ratio, power, and strain sensitivity metrics. In vivo, motors integrated into the muscle sarcomere form the more complex and hierarchically functioning muscle machine. The goal of the research reported here is to measure single myosin step-size and step-frequency in vivo to assess how tissue integration impacts motor function. A photoactivatable GFP tags the ventriculum myosin lever-arm/light-chain complex in the beating heart of a live zebrafish embryo. Detected single GFP emission reports time-resolved myosin lever-arm orientation interpreted as step-size and step-frequency providing single myosin mechanical characteristics over the active cycle. Following step-frequency of cardiac ventriculum myosin transitioning from low to high force in relaxed to auxotonic to isometric contraction phases indicates that the imposition of resisting force during contraction causes the motor to down-shift to the 3 nm step-size accounting for >80% of all the steps in the near-isometric phase. At peak force, the ATP initiated actomyosin dissociation is the predominant strain inhibited transition in the native myosin contraction cycle. The proposed model for motor down-shifting and strain sensing involves ELC N

  7. Kinetics of folding of the myosin rod.

    Science.gov (United States)

    Bechet, J J; Nozais, M

    1997-02-15

    The kinetics of the unfolding and refolding of the myosin rod have been studied by fluorescence and circular dichroism techniques, at different concentrations of protein and guanidine hydrochloride. The unfolding of the myosin rod was fast and at least biphasic in 2-3 M denaturant, with an initial immediate phase followed by a slower low-amplitude first-order phase. The refolding of the rod in 0.4-2 M guanidine hydrochloride was also at least biphasic; an initial immediate phase preceded a slow second-order phase. At the final denaturant concentration of 0.8 M, the amplitude of the burst phase was weakly dependent on the protein concentration and the rate constant of the refolding slow phase was optimal. These data are incorporated into a folding mechanism with at least three states. The high rates of the first steps of unfolding and refolding may be relevant for the functioning of the native myosin molecule by allowing a transient separation of the two strands of the myosin tail.

  8. Preparation and Characterization of Myosin Proteins.

    Science.gov (United States)

    Caldwell, Elizabeth; Eftink, Maurice R.

    1985-01-01

    Students complete five experimental projects at the end of a senior-level biochemistry course which involves the isolation and characterization of myosin and its water-soluble subfragments. Procedures used and results obtained are provided for such projects as viscosity and ATPase measurements and gel electrophoresis experiments. (JN)

  9. Myosin II dynamics are regulated by tension in intercalating cells.

    Science.gov (United States)

    Fernandez-Gonzalez, Rodrigo; Simoes, Sérgio de Matos; Röper, Jens-Christian; Eaton, Suzanne; Zallen, Jennifer A

    2009-11-01

    Axis elongation in Drosophila occurs through polarized cell rearrangements driven by actomyosin contractility. Myosin II promotes neighbor exchange through the contraction of single cell boundaries, while the contraction of myosin II structures spanning multiple pairs of cells leads to rosette formation. Here we show that multicellular actomyosin cables form at a higher frequency than expected by chance, indicating that cable assembly is an active process. Multicellular cables are sites of increased mechanical tension as measured by laser ablation. Fluorescence recovery after photobleaching experiments show that myosin II is stabilized at the cortex in regions of increased tension. Myosin II is recruited in response to an ectopic force and relieving tension leads to a rapid loss of myosin, indicating that tension is necessary and sufficient for cortical myosin localization. These results demonstrate that myosin II dynamics are regulated by tension in a positive feedback loop that leads to multicellular actomyosin cable formation and efficient tissue elongation.

  10. Distinct functional interactions between actin isoforms and nonsarcomeric myosins.

    Directory of Open Access Journals (Sweden)

    Mirco Müller

    Full Text Available Despite their near sequence identity, actin isoforms cannot completely replace each other in vivo and show marked differences in their tissue-specific and subcellular localization. Little is known about isoform-specific differences in their interactions with myosin motors and other actin-binding proteins. Mammalian cytoplasmic β- and γ-actin interact with nonsarcomeric conventional myosins such as the members of the nonmuscle myosin-2 family and myosin-7A. These interactions support a wide range of cellular processes including cytokinesis, maintenance of cell polarity, cell adhesion, migration, and mechano-electrical transduction. To elucidate differences in the ability of isoactins to bind and stimulate the enzymatic activity of individual myosin isoforms, we characterized the interactions of human skeletal muscle α-actin, cytoplasmic β-actin, and cytoplasmic γ-actin with human myosin-7A and nonmuscle myosins-2A, -2B and -2C1. In the case of nonmuscle myosins-2A and -2B, the interaction with either cytoplasmic actin isoform results in 4-fold greater stimulation of myosin ATPase activity than was observed in the presence of α-skeletal muscle actin. Nonmuscle myosin-2C1 is most potently activated by β-actin and myosin-7A by γ-actin. Our results indicate that β- and γ-actin isoforms contribute to the modulation of nonmuscle myosin-2 and myosin-7A activity and thereby to the spatial and temporal regulation of cytoskeletal dynamics. FRET-based analyses show efficient copolymerization abilities for the actin isoforms in vitro. Experiments with hybrid actin filaments show that the extent of actomyosin coupling efficiency can be regulated by the isoform composition of actin filaments.

  11. Increased expression of Myosin binding protein H in the skeletal muscle of amyotrophic lateral sclerosis patients

    KAUST Repository

    Conti, Antonio

    2014-01-01

    Amyotrophic lateral sclerosis (ALS) is a severe and fatal neurodegenerative disease of still unknown pathogenesis. Recent findings suggest that the skeletal muscle may play an active pathogenetic role. To investigate ALS\\'s pathogenesis and to seek diagnostic markers, we analyzed skeletal muscle biopsies with the differential expression proteomic approach. We studied skeletal muscle biopsies from healthy controls (CN), sporadic ALS (sALS), motor neuropathies (MN) and myopathies (M). Pre-eminently among several differentially expressed proteins, Myosin binding protein H (MyBP-H) expression in ALS samples was anomalously high. MyBP-H is a component of the thick filaments of the skeletal muscle and has strong affinity for myosin, but its function is still unclear. High MyBP-H expression level was associated with abnormal expression of Rho kinase 2 (ROCK2), LIM domain kinase 1 (LIMK1) and cofilin2, that might affect the actin-myosin interaction. We propose that MyBP-H expression level serves, as a putative biomarker in the skeletal muscle, to discriminate ALS from motor neuropathies, and that it signals the onset of dysregulation in actin-myosin interaction; this in turn might contribute to the pathogenesis of ALS. © 2013 Elsevier B.V.

  12. p21-activated kinase has substrate specificity similar to Acanthamoeba myosin I heavy chain kinase and activates Acanthamoeba myosin I.

    Science.gov (United States)

    Brzeska, H; Knaus, U G; Wang, Z Y; Bokoch, G M; Korn, E D

    1997-02-18

    Acanthamoeba class I myosins are unconventional, single-headed myosins that express actin-activated Mg2+-ATPase and in vitro motility activities only when a single serine or threonine in the heavy chain is phosphorylated by myosin I heavy chain kinase (MIHCK). Some other, but not most, class I myosins have the same consensus phosphorylation site sequence, and the two known class VI myosins have a phosphorylatable residue in the homologous position, where most myosins have an aspartate or glutamate residue. Recently, we found that the catalytic domain of Acanthamoeba MIHCK has extensive sequence similarity to the p21-activated kinase (PAK)/STE20 family of kinases from mammals and yeast, which are activated by small GTP-binding proteins. The physiological substrates of the PAK/STE20 kinases are not well characterized. In this paper we show that PAK1 has similar substrate specificity as MIHCK when assayed against synthetic substrates and that PAK1 phosphorylates the heavy chain (1 mol of P(i) per mol) and activates Acanthamoeba myosin I as MIHCK does. These results, together with the known involvement of Acanthamoeba myosin I, yeast myosin I, STE20, PAK, and small GTP-binding proteins in membrane- and cytoskeleton-associated morphogenetic transformations and activities, suggest that myosins may be physiological substrates for the PAK/STE20 family and thus mediators of these events.

  13. Stabilization of the ADP/Metaphosphate Intermediate during ATP Hydrolysis in Pre-power Stroke Myosin

    Science.gov (United States)

    Kiani, Farooq Ahmad; Fischer, Stefan

    2013-01-01

    It has been proposed recently that ATP hydrolysis in ATPase enzymes proceeds via an initial intermediate in which the dissociated γ-phosphate of ATP is bound in the protein as a metaphosphate (PγO3−). A combined quantum/classical analysis of this dissociated nucleotide state inside myosin provides a quantitative understanding of how the enzyme stabilizes this unusual metaphosphate. Indeed, in vacuum, the energy of the ADP3−·PγO3−·Mg2+ complex is much higher than that of the undissociated ATP4−. The protein brings it to a surprisingly low value. Energy decomposition reveals how much each interaction in the protein stabilizes the metaphosphate state; backbone peptides of the P-loop contribute 50% of the stabilization energy, and the side chain of Lys-185+ contributes 25%. This can be explained by the fact that these groups make strong favorable interactions with the α- and β-phosphates, thus favoring the charge distribution of the metaphosphate state over that of the ATP state. Further stabilization (16%) is achieved by a hydrogen bond between the backbone C=O of Ser-237 (on loop Switch-1) and a water molecule perfectly positioned to attack the PγO3− in the subsequent hydrolysis step. The planar and singly negative PγO3− is a much better target for the subsequent nucleophilic attack by a negatively charged OH− than the tetrahedral and doubly negative PγO42− group of ATP. Therefore, we argue that the present mechanism of metaphosphate stabilization is common to the large family of nucleotide-hydrolyzing enzymes. Methodologically, this work presents a computational approach that allows us to obtain a truly quantitative conception of enzymatic strategy. PMID:24165121

  14. Mathematical modeling of Myosin induced bistability of Lamellipodial fragments.

    Science.gov (United States)

    Hirsch, S; Manhart, A; Schmeiser, C

    2017-01-01

    For various cell types and for lamellipodial fragments on flat surfaces, externally induced and spontaneous transitions between symmetric nonmoving states and polarized migration have been observed. This behavior is indicative of bistability of the cytoskeleton dynamics. In this work, the Filament Based Lamellipodium Model (FBLM), a two-dimensional, anisotropic, two-phase continuum model for the dynamics of the actin filament network in lamellipodia, is extended by a new description of actin-myosin interaction. For appropriately chosen parameter values, the resulting model has bistable dynamics with stable states showing the qualitative features observed in experiments. This is demonstrated by numerical simulations and by an analysis of a strongly simplified version of the FBLM with rigid filaments and planar lamellipodia at the cell front and rear.

  15. Myosin-V motility: these levers were made for walking.

    Science.gov (United States)

    Tyska, Matthew J; Mooseker, Mark S

    2003-09-01

    Myosin-Va, a processive actin-based motor thought to be involved in organelle transport, now stands ready to join myosin-II (from muscle) as one of the most highly characterized members of the myosin superfamily. Recent reports from the laboratories of Goldman and colleagues and Selvin and colleagues have provided unprecedented, high-resolution views of the structural changes that take place while this motor moves along its track. Taken together, the new results indicate that myosin-Va tilts its light chain binding domains to 'walk' along actin in a hand-over-hand fashion.

  16. Orientation of spin-labeled light chain 2 of myosin heads in muscle fibers.

    Science.gov (United States)

    Arata, T

    1990-07-20

    Electron paramagnetic resonance (e.p.r.) spectroscopy has been used to monitor the orientation of spin labels attached rigidly to a reactive SH residue on the light chain 2 (LC2) of myosin heads in muscle fibers. e.p.r. spectra from spin-labeled myosin subfragment-1 (S1), allowed to diffuse into unlabeled rigor (ATP-free) fibers, were roughly approximated by a narrow angular distribution of spin labels centered at 66 degrees relative to the fiber axis, indicating a uniform orientation of S1 bound to actin. On the other hand, spectra from spin-labeled heavy meromyosin (HMM) were roughly approximated by two narrow angular distributions centered at 42 degrees and 66 degrees, suggesting that the LC2 domains of the two HMM heads have different orientations. In contrast to S1 or HMM, the spectra from rigor fibers, in which LC2 of endogenous myosin heads was labeled, showed a random orientation which may be due to distortion imposed by the structure of the filament lattice and the mismatch of the helical periodicities of the thick and thin filaments. However, spectra from the fibers in the presence of ATP analog 5'-adenylyl imidodiphosphate (AMPPNP) were approximated by two narrow angular distributions similar to those obtained with HMM. Thus, AMPPNP may cause the LC2 domain to be less flexible and/or the S2 portion to be more flexible, so as to release the distortion of the LC2 domain and make it return to its natural position. At high ionic strength, AMPPNP disoriented the spin labels as ATP did under relaxing conditions, suggesting that the myosin head is detached from and/or weakly (flexibly) attached to a thin filament.

  17. Native bare zone assemblage nucleates myosin filament assembly.

    Science.gov (United States)

    Niederman, R; Peters, L K

    1982-11-15

    Native myosin filaments from rabbit psoas muscle are always 1.5 micrometer long. The regulated assembly of these filaments is generally considered to occur by an initial antiparallel and subsequent parallel aggregation of identical myosin subunits. In this schema myosin filament length is controlled by either a self-assembly or a Vernier process. We present evidence which refines these ideas. Namely, that the intact myosin bare zone assemblage nucleates myosin filament assembly. This suggestion is based on the following experimental evidence. (1) A native bare zone assemblage about 0.3 micrometer long can be formed by dialysis of native myosin filaments to either a pH 8 or a 0.2 M-KCl solution. (2) Upon dialysis back to 0.1 M-KCl, bare zone assemblages and distal myosin molecules recombine to form 1.5 micrometer long bipolar filaments. (3) The bare zone assemblage can be separated from the distal myosin molecules by column chromatography in 0.2 M-KCl. Upon dialysis of the fractionated subsets back to 0.1 M-KCl, the bare zone assemblage retains its length of about 0.3 micrometer. However, the distal molecules reassemble to form filaments about 5 micrometers long. (4) Filaments are formed from mixes of the isolated subsets. The lengths of these filaments vary with the amount of distal myosin present. (5) When native filaments, isolated bare zone assemblages or distal myosin molecules are moved sequentially to 0.6 M-KCl and then to 0.1 M-KCl, the final filament lengths are all about 5 micrometers. The capacity of the bare zone assemblage to nucleate filament assembly may be due to the bare zone myosin molecules, the associated M band components or both.

  18. Robust mechanobiological behavior emerges in heterogeneous myosin systems

    Science.gov (United States)

    Egan, Paul F.; Moore, Jeffrey R.; Ehrlicher, Allen J.; Weitz, David A.; Schunn, Christian; Cagan, Jonathan; LeDuc, Philip

    2017-09-01

    Biological complexity presents challenges for understanding natural phenomenon and engineering new technologies, particularly in systems with molecular heterogeneity. Such complexity is present in myosin motor protein systems, and computational modeling is essential for determining how collective myosin interactions produce emergent system behavior. We develop a computational approach for altering myosin isoform parameters and their collective organization, and support predictions with in vitro experiments of motility assays with α-actinins as molecular force sensors. The computational approach models variations in single myosin molecular structure, system organization, and force stimuli to predict system behavior for filament velocity, energy consumption, and robustness. Robustness is the range of forces where a filament is expected to have continuous velocity and depends on used myosin system energy. Myosin systems are shown to have highly nonlinear behavior across force conditions that may be exploited at a systems level by combining slow and fast myosin isoforms heterogeneously. Results suggest some heterogeneous systems have lower energy use near stall conditions and greater energy consumption when unloaded, therefore promoting robustness. These heterogeneous system capabilities are unique in comparison with homogenous systems and potentially advantageous for high performance bionanotechnologies. Findings open doors at the intersections of mechanics and biology, particularly for understanding and treating myosin-related diseases and developing approaches for motor molecule-based technologies.

  19. Tension regulates myosin dynamics during Drosophila embryonic wound repair.

    Science.gov (United States)

    Kobb, Anna B; Zulueta-Coarasa, Teresa; Fernandez-Gonzalez, Rodrigo

    2017-02-15

    Embryos repair epithelial wounds rapidly in a process driven by collective cell movements. Upon wounding, actin and the molecular motor non-muscle myosin II are redistributed in the cells adjacent to the wound, forming a supracellular purse string around the lesion. Purse string contraction coordinates cell movements and drives rapid wound closure. By using fluorescence recovery after photobleaching in Drosophila embryos, we found that myosin turns over as the purse string contracts. Myosin turnover at the purse string was slower than in other actomyosin networks that had a lower level of contractility. Mathematical modelling suggested that myosin assembly and disassembly rates were both reduced by tension at the wound edge. We used laser ablation to show that tension at the purse string increased as wound closure progressed, and that the increase in tension was associated with reduced myosin turnover. Reducing purse string tension by laser-mediated severing resulted in increased turnover and loss of myosin. Finally, myosin motor activity was necessary for its stabilization around the wound and for rapid wound closure. Our results indicate that mechanical forces regulate myosin dynamics during embryonic wound repair. © 2017. Published by The Company of Biologists Ltd.

  20. Effects of proteolysis on the adenosinetriphosphatase activities of thymus myosin

    International Nuclear Information System (INIS)

    Vu, N.D.; Wagner, P.D.

    1987-01-01

    Limited proteolysis was used to identify regions on the heavy chains of calf thymus myosin which may be involved in ATP and actin binding. Assignments of the various proteolytic fragments to different parts of the myosin heavy chain were based on solubility, gel filtration, electron microscopy, and binding of 32 P-labeled regulatory light chains. Chymotrypsin rapidly cleaved within the head of thymus myosin to give a 70,000-dalton N-terminal fragment and a 140,000-dalton C-terminal fragment. These two fragments did not dissociate under nondenaturing conditions. Cleavage within the myosin tail to give heavy meromyosin occurred more slowly. Cleavage at the site 70,000 daltons from the N-terminus of the heavy chain caused about a 30-fold decrease in the actin concentration required to achieve half-maximal stimulation of the magnesium-adenosinetriphosphatase (Mg-ATPase) activity of unphosphorylated thymus myosin. The actin-activated ATPase activity of this digested myosin was only slightly affected by light chain phosphorylation. Actin inhibited the cleavage at this site by chymotrypsin. In the presence of ATP, chymotrypsin rapidly cleaved the thymus myosin heavy chain at an additional site about 4000 daltons from the N-terminus. Cleavage at this site caused a 2-fold increase in the ethylenediaminetetraacetic acid-ATPase activity and 3-fold decreases in the Ca 2+ - and Mg-ATPase activities of thymus myosin. Thus, cleavage at the N-terminus of thymus myosin was affected by ATP, and this cleavage altered ATPase activity. Papain cleaved the thymus myosin heavy chain about 94,000 daltons from the N-terminus to give subfragment 1. Although this subfragment 1 contained intact light chains, its actin-activated ATPase activity was not affected by light chain phosphorylation

  1. A Toxoplasma gondii Class XIV Myosin, Expressed in Sf9 Cells with a Parasite Co-chaperone, Requires Two Light Chains for Fast Motility*

    Science.gov (United States)

    Bookwalter, Carol S.; Kelsen, Anne; Leung, Jacqueline M.; Ward, Gary E.; Trybus, Kathleen M.

    2014-01-01

    Many diverse myosin classes can be expressed using the baculovirus/Sf9 insect cell expression system, whereas others have been recalcitrant. We hypothesized that most myosins utilize Sf9 cell chaperones, but others require an organism-specific co-chaperone. TgMyoA, a class XIVa myosin from the parasite Toxoplasma gondii, is required for the parasite to efficiently move and invade host cells. The T. gondii genome contains one UCS family myosin co-chaperone (TgUNC). TgMyoA expressed in Sf9 cells was soluble and functional only if the heavy and light chain(s) were co-expressed with TgUNC. The tetratricopeptide repeat domain of TgUNC was not essential to obtain functional myosin, implying that there are other mechanisms to recruit Hsp90. Purified TgMyoA heavy chain complexed with its regulatory light chain (TgMLC1) moved actin in a motility assay at a speed of ∼1.5 μm/s. When a putative essential light chain (TgELC1) was also bound, TgMyoA moved actin at more than twice that speed (∼3.4 μm/s). This result implies that two light chains bind to and stabilize the lever arm, the domain that amplifies small motions at the active site into the larger motions that propel actin at fast speeds. Our results show that the TgMyoA domain structure is more similar to other myosins than previously appreciated and provide a molecular explanation for how it moves actin at fast speeds. The ability to express milligram quantities of a class XIV myosin in a heterologous system paves the way for detailed structure-function analysis of TgMyoA and identification of small molecule inhibitors. PMID:25231988

  2. Novel control of cardiac myofilament response to calcium by S-glutahionylation at specific sites of myosin binding protein C

    Directory of Open Access Journals (Sweden)

    Bindiya G Patel

    2013-11-01

    Full Text Available Our previous studies demonstrated a relation between glutathionylation of cardiac myosin binding protein C and diastolic dysfunction in a hypertensive mouse model stressed by treatment with salt, deoxycorticosterone acetate, and unilateral nephrectomy. Although these results strongly indicated an important role for S-glutathionylation of myosin binding protein C as a modifier of myofilament function, indirect effects of other post-translational modifications may have occurred. Moreover, we did not determine the sites of thiol modification by glutathionylation. To address these issues, we developed an in vitro method to mimic the in situ S-glutathionylation of myofilament proteins and determined direct functional effects and sites of oxidative modification employing Western blotting and mass spectrometry. We induced glutathionylation in vitro by treatment of isolated myofibrils and detergent extracted fiber bundles (skinned fibers with oxidized glutathione (GSSG. Immuno-blotting results revealed increased glutathionylation with GSSG treatment of a protein band around 140 kDa. Using tandem mass spectrometry, we identified the 140 kDa band as cardiac myosin binding protein C and determined the sites of glutathionylation to be at cysteines 655, 479, and 627. Determination of the relation between Ca2+-activation of myofibrillar acto-myosin ATPase rate demonstrated an increased Ca2+-sensitivity induced by the S-glutathionylation. Force generating skinned fiber bundles also showed an increase in Ca-sensitivity when treated with oxidized glutathione, which was reversed with the reducing agent, dithiothreitol. Our data demonstrate that a specific and direct effect of S-glutathionylation of myosin binding protein C is a significant increase in myofilament Ca2+-sensitivity. Our data also provide new insights into the functional significance of oxidative modification of myosin binding protein C and the potential role of domains not previously considered to

  3. Three mammalian tropomyosin isoforms have different regulatory effects on nonmuscle myosin-2B and filamentous β-actin in vitro

    Science.gov (United States)

    Pathan-Chhatbar, Salma; Taft, Manuel H.; Reindl, Theresia; Hundt, Nikolas; Latham, Sharissa L.; Manstein, Dietmar J.

    2018-01-01

    The metazoan actin cytoskeleton supports a wide range of contractile and transport processes. Recent studies have shown how the dynamic association with specific tropomyosin isoforms generates actin filament populations with distinct functional properties. However, critical details of the associated molecular interactions remain unclear. Here, we report the properties of actomyosin–tropomyosin complexes containing filamentous β-actin, nonmuscle myosin-2B (NM-2B) constructs, and either tropomyosin isoform Tpm1.8cy (b.–.b.d), Tpm1.12br (b.–.b.c), or Tpm3.1cy (b.–.a.d). Our results show the extent to which the association of filamentous β-actin with these different tropomyosin cofilaments affects the actin-mediated activation of NM-2B and the release of the ATP hydrolysis products ADP and phosphate from the active site. Phosphate release gates a transition from weak to strong F-actin–binding states. The release of ADP has the opposite effect. These changes in dominant rate-limiting steps have a direct effect on the duty ratio, the fraction of time that NM-2B spends in strongly F-actin–bound states during ATP turnover. The duty ratio is increased ∼3-fold in the presence of Tpm1.12 and 5-fold for both Tpm1.8 and Tpm3.1. The presence of Tpm1.12 extends the time required per ATP hydrolysis cycle 3.7-fold, whereas it is shortened by 27 and 63% in the presence of Tpm1.8 and Tpm3.1, respectively. The resulting Tpm isoform–specific changes in the frequency, duration, and efficiency of actomyosin interactions establish a molecular basis for the ability of these complexes to support cellular processes with widely divergent demands in regard to force production, capacity to move processively, and speed of movement. PMID:29191834

  4. Self-organization of myosin II in reconstituted actomyosin bundles.

    Science.gov (United States)

    Stachowiak, Matthew R; McCall, Patrick M; Thoresen, Todd; Balcioglu, Hayri E; Kasiewicz, Lisa; Gardel, Margaret L; O'Shaughnessy, Ben

    2012-09-19

    Cells assemble a variety of bundled actomyosin structures in the cytoskeleton for activities such as cell-shape regulation, force production, and cytokinesis. Although these linear structures exhibit varied architecture, two common organizational themes are a punctate distribution of myosin II and distinct patterns of actin polarity. The mechanisms that cells use to assemble and maintain these organizational features are poorly understood. To study these, we reconstituted actomyosin bundles in vitro that contained only actin filaments and myosin II. Upon addition of ATP, the bundles contracted and the uniformly distributed myosin spontaneously reorganized into discrete clusters. We developed a mathematical model in which the motion of myosin II filaments is governed by the polarities of the actin filaments with which they interact. The model showed that the assembly of myosins into clusters is driven by their tendency to migrate to locations with zero net actin filament polarity. With no fitting parameters, the predicted distribution of myosin cluster separations was in close agreement with our experiments, including a -3/2 power law decay for intermediate length scales. Thus, without an organizing template or accessory proteins, a minimal bundle of actin and myosin has the inherent capacity to self-organize into a heterogeneous banded structure. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  5. Conductivity bound from dirty black holes

    Energy Technology Data Exchange (ETDEWEB)

    Bitaghsir Fadafan, Kazem, E-mail: bitaghsir@shahroodut.ac.ir

    2016-11-10

    We propose a lower bound of the dc electrical conductivity in strongly disordered, strongly interacting quantum field theories using holography. We study linear response of black holes with broken translational symmetry in Einstein–Maxwell-dilaton theories of gravity. Using the generalized Stokes equations at the horizon, we derive the lower bound of the electrical conductivity for the dual two dimensional disordered field theory.

  6. Phosphate and ADP Differently Inhibit Coordinated Smooth Muscle Myosin Groups

    Science.gov (United States)

    Hilbert, Lennart; Balassy, Zsombor; Zitouni, Nedjma B.; Mackey, Michael C.; Lauzon, Anne-Marie

    2015-01-01

    Actin filaments propelled in vitro by groups of skeletal muscle myosin motors exhibit distinct phases of active sliding or arrest, whose occurrence depends on actin length (L) within a range of up to 1.0 μm. Smooth muscle myosin filaments are exponentially distributed with ≈150 nm average length in vivo—suggesting relevance of the L-dependence of myosin group kinetics. Here, we found L-dependent actin arrest and sliding in in vitro motility assays of smooth muscle myosin. We perturbed individual myosin kinetics with varying, physiological concentrations of phosphate (Pi, release associated with main power stroke) and adenosine diphosphate (ADP, release associated with minor mechanical step). Adenosine triphosphate was kept constant at physiological concentration. Increasing [Pi] lowered the fraction of time for which actin was actively sliding, reflected in reduced average sliding velocity (ν) and motile fraction (fmot, fraction of time that filaments are moving); increasing [ADP] increased the fraction of time actively sliding and reduced the velocity while sliding, reflected in reduced ν and increased fmot. We introduced specific Pi and ADP effects on individual myosin kinetics into our recently developed mathematical model of actin propulsion by myosin groups. Simulations matched our experimental observations and described the inhibition of myosin group kinetics. At low [Pi] and [ADP], actin arrest and sliding were reflected by two distinct chemical states of the myosin group. Upon [Pi] increase, the probability of the active state decreased; upon [ADP] increase, the probability of the active state increased, but the active state became increasingly similar to the arrested state. PMID:25650929

  7. Structural insight into the UNC-45–myosin complex

    DEFF Research Database (Denmark)

    Fratev, Filip; Jonsdottir, Svava Osk; Pajeva, Ilza

    2013-01-01

    The UNC-45 chaperone protein interacts with and affects the folding, stability, and the ATPase activity of myosins. It plays a critical role in the cardiomyopathy development and in the breast cancer tumor growth. Here we propose the first structural model of the UNC-45–myosin complex using various...... is mainly stabilized by electrostatic interactions. Remarkably, the contact surface area is similar to that of the myosinactin complex. A significant interspecies difference in the myosin binding epitope is observed. Our results reveal the structural basis of MYH7 exons 15–16 hypertrophic cardiomyopathy...

  8. Single-molecule studies of unconventional motor protein myosin VI

    Science.gov (United States)

    Kim, HyeongJun

    Myosin VI is one of the myosin superfamily members that are actin-based molecular motors. It has received special attention due to its distinct features as compared to other myosins, such as its opposite directionality and a much larger step size than expected given the length of its "leg". This dissertation presents the author.s graduate work of several single-molecule studies on myosin VI. Special attention was paid to some of myosin VI.s tail domains that consist of proximal tail (PT), medial tail (MT), distal tail (DT) domains and cargo-binding domain (CBD). The functional form of myosin VI in cells is still under debate. Although full length myosin VI proteins in cytosolic extracts of cells were monomers from earlier studies, there are several reasons why it is now believed that myosin VI could exist as a dimer. If this is true and dimerization occurs, the next logical question would be which parts of myosin VI are dimerization regions? One model claimed that the CBD is the sole dimerization region. A competing model claimed that there must be another region that could be involved in dimerization, based on their observation that a construct without the CBD could still dimerize. Our single-molecule experiment with progressively truncated myosin VI constructs showed that the MT domain is a dimerization region, supporting the latter model. Additional single-molecule experiments and molecular dynamics (MD) simulation done with our collaborators suggest that electrostatic salt bridges formed between positive and negative amino acid residues are mainly responsible for the MT domain dimerization. After resolving this, we are left with another important question which is how myosin VI can take such a large step. Recent crystal structure showed that one of the tail domains preceding the MT domain, called the PT domain, is a three-helix bundle. The most easily conceivable way might be an unfolding of the three-helix bundle upon dimerization, allowing the protein to

  9. Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber

    International Nuclear Information System (INIS)

    Minoda, Hiroki; Okabe, Tatsuhiro; Inayoshi, Yuhri; Miyakawa, Takuya; Miyauchi, Yumiko; Tanokura, Masaru; Katayama, Eisaku; Wakabayashi, Takeyuki; Akimoto, Tsuyoshi; Sugi, Haruo

    2011-01-01

    Research highlights: → We succeeded in recording structural changes of hydrated myosin cross-bridges. → We succeeded in position-marking the cross-bridges with site-directed antibodies. → We recorded cross-bridge movement at different regions in individual cross-bridge. → The movement was smallest at the cross-bridge-subfragment two boundary. → The results provide evidence for the cross-bridge lever arm mechanism. -- Abstract: Muscle contraction results from an attachment-detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release of hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made.

  10. Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber

    Energy Technology Data Exchange (ETDEWEB)

    Minoda, Hiroki [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganeishi, Tokyo184-8588 (Japan); CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan); Okabe, Tatsuhiro; Inayoshi, Yuhri [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganeishi, Tokyo184-8588 (Japan); Miyakawa, Takuya; Miyauchi, Yumiko; Tanokura, Masaru [Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan); Katayama, Eisaku [Graduate School of Medicine, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Wakabayashi, Takeyuki [Department of Biosciences, School of Science and Engineering, Teikyo University, Utsunomiya, Tochigiken 320-8551 (Japan); Akimoto, Tsuyoshi [Department of Physiology, School of Medicine, Teikyo University, Itabashi-ku, Tokyo 173-8605 (Japan); Sugi, Haruo, E-mail: sugi@kyf.biglobe.ne.jp [Department of Physiology, School of Medicine, Teikyo University, Itabashi-ku, Tokyo 173-8605 (Japan)

    2011-02-25

    Research highlights: {yields} We succeeded in recording structural changes of hydrated myosin cross-bridges. {yields} We succeeded in position-marking the cross-bridges with site-directed antibodies. {yields} We recorded cross-bridge movement at different regions in individual cross-bridge. {yields} The movement was smallest at the cross-bridge-subfragment two boundary. {yields} The results provide evidence for the cross-bridge lever arm mechanism. -- Abstract: Muscle contraction results from an attachment-detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release of hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made.

  11. Identification of Acan125 as a myosin-I-binding protein present with myosin-I on cellular organelles of Acanthamoeba.

    Science.gov (United States)

    Xu, P; Zot, A S; Zot, H G

    1995-10-27

    We have discovered the first protein to bind to a non-filamentous myosin, aside from actin. This protein, Acan125, is a 125-kDa protein from Acanthamoeba that associates with the SH3 domain of Acanthamoeba myosin-IC and not the SH3 domain of human fodrin. Antibodies raised against Acan125 recognize a single protein of 125 kDa from a whole cell lysate of Acanthamoeba; antibodies to myosin-I (M1.7 and M1.8) do not recognize Acan125 on the same blot. Double labeling of Acanthamoeba show Acan125 and myosin-I to be present on the same intracellular organelle, most likely amoebastomes. Immunoprecipitation with either anti-myosin-I or anti-Acan125 antibodies coprecipitates both Acan125 and myosin-I from a lysate of Acanthamoeba, demonstrating that Acan125 interacts with native myosin-I.

  12. Anti-myosin humoral immune response following cardiac injury.

    Science.gov (United States)

    de Scheerder, I K; de Buyzere, M L; Delanghe, J R; Clement, D L; Wieme, R J

    1989-01-01

    A sensitive and highly specific ELISA assay was developed to determine the anti-myosin humoral immune response (AMA) in various heart diseases: acute viral myocarditis, infective endocarditis, acute myocardial infarction, and valve and coronary bypass surgery. The mean study entry AMA titer of each patient group was already significantly increased compared with age matched controls. During further follow-up (90 d) all the groups except for endocarditis showed a significant increase of AMA titer compared with their entry titer. Anti-myosin antibody titer were higher after cardiac surgery than after myocardial infarction or inflammatory heart disease. These results suggest that anti-myosin immune response is not limited to infectious processes in which the pathogen induces antibodies which cross-react with heart constituents but is merely caused by direct cardiac injury. Myosin as a major compound of heart cellular proteins turned out to be a good candidate to trigger immune response after cardiac injury.

  13. Arginylation of Myosin Heavy Chain Regulates Skeletal Muscle Strength

    Directory of Open Access Journals (Sweden)

    Anabelle S. Cornachione

    2014-07-01

    Full Text Available Protein arginylation is a posttranslational modification with an emerging global role in the regulation of actin cytoskeleton. To test the role of arginylation in the skeletal muscle, we generated a mouse model with Ate1 deletion driven by the skeletal muscle-specific creatine kinase (Ckmm promoter. Ckmm-Ate1 mice were viable and outwardly normal; however, their skeletal muscle strength was significantly reduced in comparison to controls. Mass spectrometry of isolated skeletal myofibrils showed a limited set of proteins, including myosin heavy chain, arginylated on specific sites. Atomic force microscopy measurements of contractile strength in individual myofibrils and isolated myosin filaments from these mice showed a significant reduction of contractile forces, which, in the case of myosin filaments, could be fully rescued by rearginylation with purified Ate1. Our results demonstrate that arginylation regulates force production in muscle and exerts a direct effect on muscle strength through arginylation of myosin.

  14. Gene duplication and conversion events shaped three homologous, differentially expressed myosin regulatory light chain (MLC2) genes.

    NARCIS (Netherlands)

    Gerrits, L.; Overheul, G.J.; Derks, R.C.; Wieringa, B.; Hendriks, W.J.A.J.; Wansink, D.G.

    2012-01-01

    Myosin II is a hexameric protein complex consisting of two myosin heavy chains, two myosin essential light chains and two myosin regulatory light chains. Multiple subunit isoforms exist, allowing great diversity in myosin II composition which likely impacts on its contractile properties. Little is

  15. Unitarity bound for gluon shadowing

    International Nuclear Information System (INIS)

    Kopeliovich, B. Z.; Levin, E.; Potashnikova, I. K.; Schmidt, Ivan

    2009-01-01

    Although at small Bjorken x gluons originated from different nucleons in a nucleus overlap in the longitudinal direction, most of them are still well separated in the transverse plane and therefore cannot fuse. For this reason the gluon density in nuclei cannot drop at small x below a certain bottom bound, which we evaluated in a model independent manner assuming the maximal strength of gluon fusion. We also calculated gluon shadowing in the saturated regime using the Balitsky-Kovchegov equation and found the nuclear ratio to be well above the unitarity bound. The recently updated analysis of parton distributions in nuclei, including BNL Relativistic Heavy Ion Collider (RHIC) data on high-p T hadron production at forward rapidities, led to strong gluon shadowing. Such strong shadowing and therefore the interpretation of the nuclear modification of the p T spectra in dA collisions at RHIC seem to be inconsistent with this unitarity bound.

  16. A Role for Myosin Va in Human Cytomegalovirus Nuclear Egress.

    Science.gov (United States)

    Wilkie, Adrian R; Sharma, Mayuri; Pesola, Jean M; Ericsson, Maria; Fernandez, Rosio; Coen, Donald M

    2018-03-15

    Herpesviruses replicate and package their genomes into capsids in replication compartments within the nuclear interior. Capsids then move to the inner nuclear membrane for envelopment and release into the cytoplasm in a process called nuclear egress. We previously found that nuclear F-actin is induced upon infection with the betaherpesvirus human cytomegalovirus (HCMV) and is important for nuclear egress and capsid localization away from replication compartment-like inclusions toward the nuclear rim. Despite these and related findings, it has not been shown that any specific motor protein is involved in herpesvirus nuclear egress. In this study, we have investigated whether the host motor protein, myosin Va, could be fulfilling this role. Using immunofluorescence microscopy and coimmunoprecipitation, we observed associations between a nuclear population of myosin Va and the viral major capsid protein, with both concentrating at the periphery of replication compartments. Immunoelectron microscopy showed that nearly 40% of assembled nuclear capsids associate with myosin Va. We also found that myosin Va and major capsid protein colocalize with nuclear F-actin. Importantly, antagonism of myosin Va with RNA interference or a dominant negative mutant revealed that myosin Va is important for the efficient production of infectious virus, capsid accumulation in the cytoplasm, and capsid localization away from replication compartment-like inclusions toward the nuclear rim. Our results lead us to suggest a working model whereby human cytomegalovirus capsids associate with myosin Va for movement from replication compartments to the nuclear periphery during nuclear egress. IMPORTANCE Little is known regarding how newly assembled and packaged herpesvirus capsids move from the nuclear interior to the periphery during nuclear egress. While it has been proposed that an actomyosin-based mechanism facilitates intranuclear movement of alphaherpesvirus capsids, a functional role for

  17. Long-range coupling between ATP-binding and lever-arm regions in myosin via dielectric allostery

    Science.gov (United States)

    Sato, Takato; Ohnuki, Jun; Takano, Mitsunori

    2017-12-01

    A protein molecule is a dielectric substance, so the binding of a ligand is expected to induce dielectric response in the protein molecule, considering that ligands are charged or polar in general. We previously reported that binding of adenosine triphosphate (ATP) to molecular motor myosin actually induces such a dielectric response in myosin due to the net negative charge of ATP. By this dielectric response, referred to as "dielectric allostery," spatially separated two regions in myosin, the ATP-binding region and the actin-binding region, are allosterically coupled. In this study, from the statistically stringent analyses of the extensive molecular dynamics simulation data obtained in the ATP-free and the ATP-bound states, we show that there exists the dielectric allostery that transmits the signal of ATP binding toward the distant lever-arm region. The ATP-binding-induced electrostatic potential change observed on the surface of the main domain induced a movement of the converter subdomain from which the lever arm extends. The dielectric response was found to be caused by an underlying large-scale concerted rearrangement of the electrostatic bond network, in which highly conserved charged/polar residues are involved. Our study suggests the importance of the dielectric property for molecular machines in exerting their function.

  18. Oxidation of myosin by haem proteins generates myosin radicals and protein cross-links

    DEFF Research Database (Denmark)

    Lametsch, Marianne Lund; Luxford, Catherine; Skibsted, Leif Horsfelt

    2008-01-01

    as a result of the reaction with activated haem proteins (horseradish peroxidase/H2O2) and met-myoglobin/H2O2) has been investigated by EPR spectroscopy and amino-acid consumption, product formation has been characterized by HPLC, and changes in protein integrity have been determined by SDS/PAGE. Multiple...... of thiyl and tyrosyl radicals is consistent with the observed consumption of cysteine and tyrosine residues, the detection of di-tyrosine by HPLC and the detection of both reducible (disulfide bond) and non-reducible cross-links between myosin molecules by SDS/PAGE. The time course of radical formation...

  19. Perceptron Mistake Bounds

    OpenAIRE

    Mohri, Mehryar; Rostamizadeh, Afshin

    2013-01-01

    We present a brief survey of existing mistake bounds and introduce novel bounds for the Perceptron or the kernel Perceptron algorithm. Our novel bounds generalize beyond standard margin-loss type bounds, allow for any convex and Lipschitz loss function, and admit a very simple proof.

  20. Circuit lower bounds in bounded arithmetics

    Czech Academy of Sciences Publication Activity Database

    Pich, Ján

    2015-01-01

    Roč. 166, č. 1 (2015), s. 29-45 ISSN 0168-0072 R&D Projects: GA AV ČR IAA100190902 Keywords : bounded arithmetic * circuit lower bounds Subject RIV: BA - General Mathematics Impact factor: 0.582, year: 2015 http://www.sciencedirect.com/science/article/pii/S0168007214000888

  1. Calcium-regulated import of myosin IC into the nucleus.

    Science.gov (United States)

    Maly, Ivan V; Hofmann, Wilma A

    2016-06-01

    Myosin IC is a molecular motor involved in intracellular transport, cell motility, and transcription. Its mechanical properties are regulated by calcium via calmodulin binding, and its functions in the nucleus depend on import from the cytoplasm. The import has recently been shown to be mediated by the nuclear localization signal located within the calmodulin-binding domain. In the present paper, it is demonstrated that mutations in the calmodulin-binding sequence shift the intracellular distribution of myosin IC to the nucleus. The redistribution is displayed by isoform B, described originally as the "nuclear myosin," but is particularly pronounced with isoform C, the normally cytoplasmic isoform. Furthermore, experimental elevation of the intracellular calcium concentration induces a rapid import of myosin into the nucleus. The import is blocked by the importin β inhibitor importazole. These findings are consistent with a mechanism whereby calmodulin binding prevents recognition of the nuclear localization sequence by importin β, and the steric inhibition of import is released by cell signaling leading to the intracellular calcium elevation. The results establish a mechanistic connection between the calcium regulation of the motor function of myosin IC in the cytoplasm and the induction of its import into the nucleus. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  2. Excessive Myosin Activity in Mbs Mutants Causes Photoreceptor Movement Out of the Drosophila Eye Disc Epithelium

    OpenAIRE

    Lee, Arnold; Treisman, Jessica E.

    2004-01-01

    Neuronal cells must extend a motile growth cone while maintaining the cell body in its original position. In migrating cells, myosin contraction provides the driving force that pulls the rear of the cell toward the leading edge. We have characterized the function of myosin light chain phosphatase, which down-regulates myosin activity, in Drosophila photoreceptor neurons. Mutations in the gene encoding the myosin binding subunit of this enzyme cause photoreceptors to drop out of the eye disc e...

  3. Unfolding/refolding studies of the myosin rod.

    Science.gov (United States)

    Nozais, M; Bechet, J J

    1993-12-15

    The effect of guanidine hydrochloride on the gel-filtration chromatography, viscosity, far ultraviolet circular dichroism and fluorescence emission intensity of the myosin rod was studied under equilibrium conditions. The normalized transition curves for each of these methods were comparable with a midpoint at a guanidine hydrochloride concentration of 1.75-2 M. The curves were not, however, superposable, suggesting that the loss of helix content and the dissociation of the two chains of the myosin rod were not tightly linked. Furthermore, they were unexpectedly independent of the protein concentration over 0.05-20 microM. These phenomena are interpreted taking into account the large size of the molecule. A step-wise process is proposed as a model for the unfolding of the myosin rod.

  4. Catalytic strategy used by the myosin motor to hydrolyze ATP.

    Science.gov (United States)

    Kiani, Farooq Ahmad; Fischer, Stefan

    2014-07-22

    Myosin is a molecular motor responsible for biological motions such as muscle contraction and intracellular cargo transport, for which it hydrolyzes adenosine 5'-triphosphate (ATP). Early steps of the mechanism by which myosin catalyzes ATP hydrolysis have been investigated, but still missing are the structure of the final ADP·inorganic phosphate (Pi) product and the complete pathway leading to it. Here, a comprehensive description of the catalytic strategy of myosin is formulated, based on combined quantum-classical molecular mechanics calculations. A full exploration of catalytic pathways was performed and a final product structure was found that is consistent with all experiments. Molecular movies of the relevant pathways show the different reorganizations of the H-bond network that lead to the final product, whose γ-phosphate is not in the previously reported HPγO4(2-) state, but in the H2PγO4(-) state. The simulations reveal that the catalytic strategy of myosin employs a three-pronged tactic: (i) Stabilization of the γ-phosphate of ATP in a dissociated metaphosphate (PγO3(-)) state. (ii) Polarization of the attacking water molecule, to abstract a proton from that water. (iii) Formation of multiple proton wires in the active site, for efficient transfer of the abstracted proton to various product precursors. The specific role played in this strategy by each of the three loops enclosing ATP is identified unambiguously. It explains how the precise timing of the ATPase activation during the force generating cycle is achieved in myosin. The catalytic strategy described here for myosin is likely to be very similar in most nucleotide hydrolyzing enzymes.

  5. Myosin heavy chain expression in rabbit masseter muscle during postnatal development

    NARCIS (Netherlands)

    Bredman, J. J.; Weijs, W. A.; Korfage, H. A.; Brugman, P.; Moorman, A. F.

    1992-01-01

    The expression of isoforms of myosin heavy chain (MHC) during postnatal development was studied in the masseter muscle of the rabbit. Evidence is presented that in addition to adult fast and slow myosin, the rabbit masseter contains neonatal and 'cardiac' alpha-MHC. During postnatal growth myosin

  6. Complexity Bounds for Quantum Computation

    Science.gov (United States)

    2007-06-22

    iently thanin lassi al omputation, onstru tion of small ir uits whi h an arry out phase estimation, show-ing that the quantum ontent of strong...on lower bounds for omputing parity or fanout using onstant or log depth quantum ir uits, quantum simulations of lassi al ir uit elements and...lasses, su h as thresh-old and mod fun tions, and the general relationships between quantum omplexity lasses and orre-sponding lassi al lasses

  7. A matrix lower bound

    Energy Technology Data Exchange (ETDEWEB)

    Grcar, Joseph F.

    2002-02-04

    A matrix lower bound is defined that generalizes ideas apparently due to S. Banach and J. von Neumann. The matrix lower bound has a natural interpretation in functional analysis, and it satisfies many of the properties that von Neumann stated for it in a restricted case. Applications for the matrix lower bound are demonstrated in several areas. In linear algebra, the matrix lower bound of a full rank matrix equals the distance to the set of rank-deficient matrices. In numerical analysis, the ratio of the matrix norm to the matrix lower bound is a condition number for all consistent systems of linear equations. In optimization theory, the matrix lower bound suggests an identity for a class of min-max problems. In real analysis, a recursive construction that depends on the matrix lower bound shows that the level sets of continuously differential functions lie asymptotically near those of their tangents.

  8. Mouse nuclear myosin I knock-out shows interchangeability and redundancy of myosin isoforms in the cell nucleus

    Czech Academy of Sciences Publication Activity Database

    Venit, Tomáš; Dzijak, Rastislav; Kalendová, Alžběta; Kahle, Michal; Rohožková, Jana; Schmidt, V.; Rülicke, T.; Rathkolb, B.; Hans, W.; Bohla, A.; Eickelberg, O.; Stoeger, T.; Wolf, E.; Yildirim, A.Ö.; Gailus-Durner, V.; Fuchs, H.; de Angelis, M.H.; Hozák, Pavel

    2013-01-01

    Roč. 8, č. 4 (2013), e61406 E-ISSN 1932-6203 R&D Projects: GA ČR GAP305/11/2232; GA TA ČR TE01020022; GA MŠk LH12143; GA ČR(CZ) GD204/09/H084 Institutional research plan: CEZ:AV0Z50520514 Institutional support: RVO:68378050 Keywords : nuclear myosin * myosin isoforms * cell nucleus Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.534, year: 2013

  9. Temperature-induced structural changes in the myosin thick filament of skinned rabbit psoas muscle.

    Science.gov (United States)

    Malinchik, S; Xu, S; Yu, L C

    1997-11-01

    and disordered cross-bridge populations in muscle (Poulsen, F. R., and J. Lowy. 1983. Small angle scattering from myosin heads in relaxed and rigor frog skeletal muscle. Nature (Lond.). 303:146-152.). However, our results added new insights into the disordered population. Present modeling together with data analysis (Xu, S., S. Malinchik, Th. Kraft, B. Brenner, and L. C. Yu. 1997. X-ray diffraction studies of cross-bridges weakly bound to actin in relaxed skinned fibers of rabbit psoas muscle. Biophys. J. 73:000-000) indicate that in a relaxed muscle, cross-bridges are distributed in three populations: those that are ordered on the thick filament helix and those that are disordered; and within the disordered population, some cross-bridges are detached and some are weakly attached to actin. One critical conclusion of the present study is that the apparent order disorder transition as a function of temperature is not due to an increase/decrease in thermal motion (temperature factor) for the entire population, but a redistribution of cross-bridges among the three populations. Changing the temperature leads to a change in the fraction of cross-bridges located on the helix, while changing the ionic strength at a given temperature affects the disordered population leading to a change in the relative fraction of cross-bridges detached from and weakly attached to actin. Since the redistribution is reversible, we suggest that there is an equilibrium among the three populations of cross-bridges.

  10. Design considerations in coiled-coil fusion constructs for the structural determination of a problematic region of the human cardiac myosin rod

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, Michael P.; Ajay, Gautam; Gellings, Jaclyn A.; Rayment, Ivan (UW)

    2017-12-01

    X-ray structural determination of segments of the myosin rod has proved difficult because of the strong salt-dependent aggregation properties and repeating pattern of charges on the surface of the coiled-coil that lead to the formation of paracrystals. This problem has been resolved in part through the use of globular assembly domains that improve protein folding and prevent aggregation. The primary consideration now in designing coiled-coil fusion constructs for myosin is deciding where to truncate the coiled-coil and which amino acid residues to include from the folding domain. This is especially important for myosin that contains numerous regions of low predicted coiled-coil propensity. Here we describe the strategy adopted to determine the structure of the region that extends from Arg1677 – Leu1797 that included two areas that do not show a strong sequence signature of a conventional left-handed coiled coil or canonical heptad repeat. This demonstrates again that, with careful choice of fusion constructs, overlapping structures exhibit very similar conformations for the myosin rod fragments in the canonical regions. However, conformational variability is seen around Leu1706 which is a hot spot for cardiomyopathy mutations suggesting that this might be important for function.

  11. Design considerations in coiled-coil fusion constructs for the structural determination of a problematic region of the human cardiac myosin rod.

    Science.gov (United States)

    Andreas, Michael P; Ajay, Gautam; Gellings, Jaclyn A; Rayment, Ivan

    2017-12-01

    X-ray structural determination of segments of the myosin rod has proved difficult because of the strong salt-dependent aggregation properties and repeating pattern of charges on the surface of the coiled-coil that lead to the formation of paracrystals. This problem has been resolved in part through the use of globular assembly domains that improve protein folding and prevent aggregation. The primary consideration now in designing coiled-coil fusion constructs for myosin is deciding where to truncate the coiled-coil and which amino acid residues to include from the folding domain. This is especially important for myosin that contains numerous regions of low predicted coiled-coil propensity. Here we describe the strategy adopted to determine the structure of the region that extends from Arg1677 - Leu1797 that included two areas that do not show a strong sequence signature of a conventional left-handed coiled coil or canonical heptad repeat. This demonstrates again that, with careful choice of fusion constructs, overlapping structures exhibit very similar conformations for the myosin rod fragments in the canonical regions. However, conformational variability is seen around Leu1706 which is a hot spot for cardiomyopathy mutations suggesting that this might be important for function. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Transportation of Nanoscale Cargoes by Myosin Propelled Actin Filaments

    NARCIS (Netherlands)

    Persson, Malin; Gullberg, Maria; Tolf, Conny; Lindberg, A. Michael; Mansson, Alf; Kocer, Armagan

    2013-01-01

    Myosin II propelled actin filaments move ten times faster than kinesin driven microtubules and are thus attractive candidates as cargo-transporting shuttles in motor driven lab-on-a-chip devices. In addition, actomyosin-based transportation of nanoparticles is useful in various fundamental studies.

  13. Space exploration by dendritic cells requires maintenance of myosin II activity by IP3 receptor 1.

    Science.gov (United States)

    Solanes, Paola; Heuzé, Mélina L; Maurin, Mathieu; Bretou, Marine; Lautenschlaeger, Franziska; Maiuri, Paolo; Terriac, Emmanuel; Thoulouze, Maria-Isabel; Launay, Pierre; Piel, Matthieu; Vargas, Pablo; Lennon-Duménil, Ana-Maria

    2015-03-12

    Dendritic cells (DCs) patrol the interstitial space of peripheral tissues. The mechanisms that regulate their migration in such constrained environment remain unknown. We here investigated the role of calcium in immature DCs migrating in confinement. We found that they displayed calcium oscillations that were independent of extracellular calcium and more frequently observed in DCs undergoing strong speed fluctuations. In these cells, calcium spikes were associated with fast motility phases. IP₃ receptors (IP₃Rs) channels, which allow calcium release from the endoplasmic reticulum, were identified as required for immature DCs to migrate at fast speed. The IP₃R1 isoform was further shown to specifically regulate the locomotion persistence of immature DCs, that is, their capacity to maintain directional migration. This function of IP₃R1 results from its ability to control the phosphorylation levels of myosin II regulatory light chain (MLC) and the back/front polarization of the motor protein. We propose that by upholding myosin II activity, constitutive calcium release from the ER through IP₃R1 maintains DC polarity during migration in confinement, facilitating the exploration of their environment. © 2015 Institut Curie/Inserm. Published under the terms of the CC BY NC ND 4.0 license.

  14. The myosin chaperone UNC45B is involved in lens development and autosomal dominant juvenile cataract

    DEFF Research Database (Denmark)

    Hansen, Lars; Comyn, Sophie; Mang, Yuan

    2014-01-01

    in this region, in ACACA and UNC45B. As alterations of the UNC45B protein have been shown to affect eye development in model organisms, effort was focused on the heterozygous UNC45B missense mutation. UNC45B encodes a myosin-specific chaperone that, together with the general heat shock protein HSP90, is involved...... in myosin assembly. The mutation changes p.Arg805 to Trp in the UCS domain, an amino acid that is highly conserved from yeast to human. UNC45B is strongly expressed in the heart and skeletal muscle tissue, but here we show expression in human embryo eye and zebrafish lens. The zebrafish mutant steif......, carrying an unc45b nonsense mutation, has smaller eyes than wild-type embryos and shows accumulation of nuclei in the lens. Injection of RNA encoding the human wild-type UNC45B protein into the steif homozygous embryo reduced the nuclei accumulation and injection of human mutant UNC45B cDNA in wild...

  15. Physical Uncertainty Bounds (PUB)

    Energy Technology Data Exchange (ETDEWEB)

    Vaughan, Diane Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Preston, Dean L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-19

    This paper introduces and motivates the need for a new methodology for determining upper bounds on the uncertainties in simulations of engineered systems due to limited fidelity in the composite continuum-level physics models needed to simulate the systems. We show that traditional uncertainty quantification methods provide, at best, a lower bound on this uncertainty. We propose to obtain bounds on the simulation uncertainties by first determining bounds on the physical quantities or processes relevant to system performance. By bounding these physics processes, as opposed to carrying out statistical analyses of the parameter sets of specific physics models or simply switching out the available physics models, one can obtain upper bounds on the uncertainties in simulated quantities of interest.

  16. Photon virtual bound state

    International Nuclear Information System (INIS)

    Inoue, J.; Ohtaka, K.

    2004-01-01

    We study virtual bound states in photonics, which are a vectorial extension of electron virtual bound states. The condition for these states is derived. It is found that the Mie resonant state which satisfies the condition that the size parameter is less than the angular momentum should be interpreted as a photon virtual bound state. In order to confirm the validity of the concept, we compare the photonic density of states, the width of which represents the lifetime of the photon virtual bound states, with numerical results

  17. Effective bounds on strong unicity in L1-approximation

    DEFF Research Database (Denmark)

    Kohlenbach, Ulrich; Oliva, Paulo B.

    In this paper we present another case study in the general project of Proof Mining which means the logical analysis of prima facie non-effective proofs with the aim of extracting new computationally relevant data. We use techniques based on monotone functional interpretation (developed in [17]) t...

  18. Coulomb plus strong interaction bound states - momentum space numerical solutions

    International Nuclear Information System (INIS)

    Heddle, D.P.; Tabakin, F.

    1985-01-01

    The levels and widths of hadronic atoms are calculated in momentum space using an inverse algorithm for the eigenvalue problem. The Coulomb singularity is handled by the Lande substraction method. Relativistic, nonlocal, complex hadron-nucleus interactions are incorporated as well as vacuum polarization and finite size effects. Coordinate space wavefunctions are obtained by employing a Fourier Bessel transformation. (orig.)

  19. Diffusion of myosin light chain kinase on actin: A mechanism to enhance myosin phosphorylation rates in smooth muscle.

    Science.gov (United States)

    Hong, Feng; Brizendine, Richard K; Carter, Michael S; Alcala, Diego B; Brown, Avery E; Chattin, Amy M; Haldeman, Brian D; Walsh, Michael P; Facemyer, Kevin C; Baker, Josh E; Cremo, Christine R

    2015-10-01

    Smooth muscle myosin (SMM) light chain kinase (MLCK) phosphorylates SMM, thereby activating the ATPase activity required for muscle contraction. The abundance of active MLCK, which is tightly associated with the contractile apparatus, is low relative to that of SMM. SMM phosphorylation is rapid despite the low ratio of MLCK to SMM, raising the question of how one MLCK rapidly phosphorylates many SMM molecules. We used total internal reflection fluorescence microscopy to monitor single molecules of streptavidin-coated quantum dot-labeled MLCK interacting with purified actin, actin bundles, and stress fibers of smooth muscle cells. Surprisingly, MLCK and the N-terminal 75 residues of MLCK (N75) moved on actin bundles and stress fibers of smooth muscle cell cytoskeletons by a random one-dimensional (1-D) diffusion mechanism. Although diffusion of proteins along microtubules and oligonucleotides has been observed previously, this is the first characterization to our knowledge of a protein diffusing in a sustained manner along actin. By measuring the frequency of motion, we found that MLCK motion is permitted only if acto-myosin and MLCK-myosin interactions are weak. From these data, diffusion coefficients, and other kinetic and geometric considerations relating to the contractile apparatus, we suggest that 1-D diffusion of MLCK along actin (a) ensures that diffusion is not rate limiting for phosphorylation, (b) allows MLCK to locate to areas in which myosin is not yet phosphorylated, and (c) allows MLCK to avoid getting "stuck" on myosins that have already been phosphorylated. Diffusion of MLCK along actin filaments may be an important mechanism for enhancing the rate of SMM phosphorylation in smooth muscle. © 2015 Hong et al.

  20. Harmonic Force Spectroscopy Reveals a Force-Velocity Curve from a Single Human Beta Cardiac Myosin Motor

    DEFF Research Database (Denmark)

    Sung, Jongmin; Nag, Suman; Vestergaard, Christian L.

    2014-01-01

    in thin filaments in the sarcomere, cycling between a strongly bound state (force producing state) and a weakly bound state (relaxed state). Huxley and Simmons have previously proposed that the transition from the strong to the weak interaction can be modulated by an external load, i.e., the transition...

  1. The DMM Bound

    DEFF Research Database (Denmark)

    Emiris, Ioannis Z.; Mourrain, Bernard; Tsigaridas, Elias

    2010-01-01

    In this paper we derive aggregate separation bounds, named after Davenport-Mahler-Mignotte (DMM), on the isolated roots of polynomial systems, specifically on the minimum distance between any two such roots. The bounds exploit the structure of the system and the height of the sparse (or toric) re...

  2. Bounded Gaussian process regression

    DEFF Research Database (Denmark)

    Jensen, Bjørn Sand; Nielsen, Jens Brehm; Larsen, Jan

    2013-01-01

    We extend the Gaussian process (GP) framework for bounded regression by introducing two bounded likelihood functions that model the noise on the dependent variable explicitly. This is fundamentally different from the implicit noise assumption in the previously suggested warped GP framework. We...

  3. Quantum Bounded Symmetric Domains

    OpenAIRE

    Vaksman, L. L.

    2008-01-01

    This is Leonid Vaksman's monograph "Quantum bounded symmetric domains" (in Russian), preceded with an English translation of the table of contents and (a part) of the introduction. Quantum bounded symmetric domains are interesting from several points of view. In particular, they provide interesting examples for noncommutative complex analysis (i.e., the theory of subalgebras of C^*-algebars) initiated by W. Arveson.

  4. Distribution and evolution of stable single α-helices (SAH domains in myosin motor proteins.

    Directory of Open Access Journals (Sweden)

    Dominic Simm

    Full Text Available Stable single-alpha helices (SAHs are versatile structural elements in many prokaryotic and eukaryotic proteins acting as semi-flexible linkers and constant force springs. This way SAH-domains function as part of the lever of many different myosins. Canonical myosin levers consist of one or several IQ-motifs to which light chains such as calmodulin bind. SAH-domains provide flexibility in length and stiffness to the myosin levers, and may be particularly suited for myosins working in crowded cellular environments. Although the function of the SAH-domains in human class-6 and class-10 myosins has well been characterised, the distribution of the SAH-domain in all myosin subfamilies and across the eukaryotic tree of life remained elusive. Here, we analysed the largest available myosin sequence dataset consisting of 7919 manually annotated myosin sequences from 938 species representing all major eukaryotic branches using the SAH-prediction algorithm of Waggawagga, a recently developed tool for the identification of SAH-domains. With this approach we identified SAH-domains in more than one third of the supposed 79 myosin subfamilies. Depending on the myosin class, the presence of SAH-domains can range from a few to almost all class members indicating complex patterns of independent and taxon-specific SAH-domain gain and loss.

  5. Bounding species distribution models

    Directory of Open Access Journals (Sweden)

    Thomas J. STOHLGREN, Catherine S. JARNEVICH, Wayne E. ESAIAS,Jeffrey T. MORISETTE

    2011-10-01

    Full Text Available Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for “clamping” model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART and maximum entropy (Maxent models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5: 642–647, 2011].

  6. Bounding Species Distribution Models

    Science.gov (United States)

    Stohlgren, Thomas J.; Jarnevich, Cahterine S.; Morisette, Jeffrey T.; Esaias, Wayne E.

    2011-01-01

    Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5): 642-647, 2011].

  7. Myosin-1A Targets to Microvilli Using Multiple Membrane Binding Motifs in the Tail Homology 1 (TH1) Domain*

    Science.gov (United States)

    Mazerik, Jessica N.; Tyska, Matthew J.

    2012-01-01

    One of the most abundant components of the enterocyte brush border is the actin-based monomeric motor, myosin-1a (Myo1a). Within brush border microvilli, Myo1a carries out a number of critical functions at the interface between membrane and actin cytoskeleton. Proper physiological function of Myo1a depends on its ability to bind to microvillar membrane, an interaction mediated by a C-terminal tail homology 1 (TH1) domain. However, little is known about the mechanistic details of the Myo1a-TH1/membrane interaction. Structure-function analysis of Myo1a-TH1 targeting in epithelial cells revealed that an N-terminal motif conserved among class I myosins and a C-terminal motif unique to Myo1a-TH1 are both required for steady state microvillar enrichment. Purified Myo1a bound to liposomes composed of phosphatidylserine and phosphoinositol 4,5-bisphosphate, with moderate affinity in a charge-dependent manner. Additionally, peptides of the N- and C-terminal regions required for targeting were able to compete with Myo1a for binding to highly charged liposomes in vitro. Single molecule total internal reflection fluorescence microscopy showed that these motifs are also necessary for slowing the membrane detachment rate in cells. Finally, Myo1a-TH1 co-localized with both lactadherin-C2 (a phosphatidylserine-binding protein) and PLCδ1-PH (a phosphoinositol 4,5-bisphosphate-binding protein) in microvilli, but only lactaderin-C2 expression reduced brush border targeting of Myo1a-TH1. Together, our results suggest that Myo1a targeting to microvilli is driven by membrane binding potential that is distributed throughout TH1 rather than localized to a single motif. These data highlight the diversity of mechanisms that enable different class I myosins to target membranes in distinct biological contexts. PMID:22367206

  8. Increased myocardial short-range forces in a rodent model of diabetes reflect elevated content of β myosin heavy chain.

    Science.gov (United States)

    Chung, Charles S; Mitov, Mihail I; Callahan, Leigh Ann; Campbell, Kenneth S

    2014-06-15

    Diastolic dysfunction is a clinically significant problem for patients with diabetes and often reflects increased ventricular stiffness. Attached cross-bridges contribute to myocardial stiffness and produce short-range forces, but it is not yet known whether these forces are altered in diabetes. In this study, we tested the hypothesis that cross-bridge-based short-range forces are increased in the streptozotocin (STZ) induced rat model of type 1 diabetes. Chemically permeabilized myocardial preparations were obtained from 12week old rats that had been injected with STZ or vehicle 4weeks earlier, and activated in solutions with pCa (=-log10[Ca(2+)]) values ranging from 9.0 to 4.5. The short-range forces elicited by controlled length changes were ∼67% greater in the samples from the diabetic rats than in the control preparations. This change was mostly due to an increased elastic limit (the length change at the peak short-range force) as opposed to increased passive muscle stiffness. The STZ-induced increase in short-ranges forces is thus unlikely to reflect changes to titin and/or collagen filaments. Gel electrophoresis showed that STZ increased the relative expression of β myosin heavy chain. This molecular mechanism can explain the increased short-ranges forces observed in the diabetic tissue if β myosin molecules remain bound between the filaments for longer durations than α molecules during imposed movements. These results suggest that interventions that decrease myosin attachment times may be useful treatments for diastolic dysfunction associated with diabetes. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Stress generation by myosin minifilaments in actin bundles.

    Science.gov (United States)

    Dasanayake, Nilushi L; Carlsson, Anders E

    2013-06-01

    Forces and stresses generated by the action of myosin minifilaments are analyzed in idealized computer-generated actin bundles, and compared to results for isotropic actin networks. The bundles are generated as random collections of actin filaments in two dimensions with constrained orientations, crosslinked and attached to two fixed walls. Myosin minifilaments are placed on actin filament pairs and allowed to move and deform the network so that it exerts forces on the walls. The vast majority of simulation runs end with contractile minifilament stress, because minifilaments rotate into energetically stable contractile configurations. This process is aided by the bending and stretching of actin filaments, which accomodate minifilament rotation. Stresses for bundles are greater than those for isotropic networks, and antiparallel filaments generate more tension than parallel filaments. The forces transmitted by the actin network to the walls of the simulation cell often exceed the tension in the minifilament itself.

  10. Stabilization of the ADP/metaphosphate intermediate during ATP hydrolysis in pre-power stroke myosin: quantitative anatomy of an enzyme.

    Science.gov (United States)

    Kiani, Farooq Ahmad; Fischer, Stefan

    2013-12-06

    It has been proposed recently that ATP hydrolysis in ATPase enzymes proceeds via an initial intermediate in which the dissociated γ-phosphate of ATP is bound in the protein as a metaphosphate (PγO3(-)). A combined quantum/classical analysis of this dissociated nucleotide state inside myosin provides a quantitative understanding of how the enzyme stabilizes this unusual metaphosphate. Indeed, in vacuum, the energy of the ADP(3-) · PγO3(-) · Mg(2+) complex is much higher than that of the undissociated ATP(4-). The protein brings it to a surprisingly low value. Energy decomposition reveals how much each interaction in the protein stabilizes the metaphosphate state; backbone peptides of the P-loop contribute 50% of the stabilization energy, and the side chain of Lys-185(+) contributes 25%. This can be explained by the fact that these groups make strong favorable interactions with the α- and β-phosphates, thus favoring the charge distribution of the metaphosphate state over that of the ATP state. Further stabilization (16%) is achieved by a hydrogen bond between the backbone C=O of Ser-237 (on loop Switch-1) and a water molecule perfectly positioned to attack the PγO3(-) in the subsequent hydrolysis step. The planar and singly negative PγO3(-) is a much better target for the subsequent nucleophilic attack by a negatively charged OH(-) than the tetrahedral and doubly negative PγO4(2-) group of ATP. Therefore, we argue that the present mechanism of metaphosphate stabilization is common to the large family of nucleotide-hydrolyzing enzymes. Methodologically, this work presents a computational approach that allows us to obtain a truly quantitative conception of enzymatic strategy.

  11. AN INTEGRATIVE WAY OF TEACHING MOLECULAR CELL BIOLOGY AND PROTEIN CHEMISTRY USING ACTIN IMMOBILIZATION ON CHITIN FOR PURIFYING MYOSIN II.

    Directory of Open Access Journals (Sweden)

    M.G. Souza

    2007-05-01

    Full Text Available Our intent is to present our experience on teaching Molecular Cell Biology andProtein Chemistry at UNIRIO through an innovative approach that includes myosin IIextraction and purification. We took advantage of the properties of muscle contractionand propose a simple method for purifying myosin II by affinity chromatography. Thisoriginal method is based on the preparation of an affinity column containing actinmolecules covalently bound to chitin particles. We propose a three-week syllabus thatincludes lectures and bench experimental work. The syllabus favors the activelearning of protein extraction and purification, as well as, of scientific concepts suchas muscle contraction, cytoskeleton structure and its importance for the living cell. Italso promotes the learning of the biotechnological applications of chitin and theapplications of protein immobilization in different industrial fields. Furthermore, theactivities also target the development of laboratorial technical abilities, thedevelopment of problem solving skills and the ability to write up a scientific reportfollowing the model of a scientific article. It is very important to mention that thissyllabus can be used even in places where a facility such as ultra-centrifugation islacking.

  12. Myosin Vs organize actin cables in fission yeast.

    Science.gov (United States)

    Lo Presti, Libera; Chang, Fred; Martin, Sophie G

    2012-12-01

    Myosin V motors are believed to contribute to cell polarization by carrying cargoes along actin tracks. In Schizosaccharomyces pombe, Myosin Vs transport secretory vesicles along actin cables, which are dynamic actin bundles assembled by the formin For3 at cell poles. How these flexible structures are able to extend longitudinally in the cell through the dense cytoplasm is unknown. Here we show that in myosin V (myo52 myo51) null cells, actin cables are curled, bundled, and fail to extend into the cell interior. They also exhibit reduced retrograde flow, suggesting that formin-mediated actin assembly is impaired. Myo52 may contribute to actin cable organization by delivering actin regulators to cell poles, as myoV defects are partially suppressed by diverting cargoes toward cell tips onto microtubules with a kinesin 7-Myo52 tail chimera. In addition, Myo52 motor activity may pull on cables to provide the tension necessary for their extension and efficient assembly, as artificially tethering actin cables to the nuclear envelope via a Myo52 motor domain restores actin cable extension and retrograde flow in myoV mutants. Together these in vivo data reveal elements of a self-organizing system in which the motors shape their own tracks by transporting cargoes and exerting physical pulling forces.

  13. The role of actin and myosin during spermatogenesis.

    Science.gov (United States)

    Sun, Xiao; Kovacs, Tamas; Hu, Yan-Jun; Yang, Wan-Xi

    2011-08-01

    Spermatogenesis is a transitionary process in which the diploid spermatogonia transform into haploid mature spermatozoa. Actin and myosin have been implicated in various aspects during spermatogenesis. Actin is present in the form of monomer, oligomer and polymer within cells, the latter is called microfilament. There are five actin-containing structures during spermatogenesis, i.e., ectoplasmic specialization, acroplaxome, manchette in mammals, actin cones in Drosophila and acroframosome in Caridean shrimp. They are involved in the shaping and differentiating of spermatids. Along with spermatogenesis, the actin cytoskeletons show active remodeling in this process. Some actin binding or actin regulated proteins have been demonstrated to regulate dynamic changes of the actin-containing structures. Myosin, actin-dependent molecular motor, plays an important role during spermatogenesis, such as involving in acrosome biogenesis, vesicle transport, gene transcription and nuclear shaping. The actin cytoskeleton and actin binding/regulated proteins cooperate to facilitate spermatogenesis. In this review, we summarize the existing knowledge about the cytoskeletal structures consisting of actin, actin binding/regulated proteins and myosin during spermatogenesis.

  14. Tropomyosin isoforms bias actin track selection by vertebrate myosin Va

    Science.gov (United States)

    Sckolnick, Maria; Krementsova, Elena B.; Warshaw, David M.; Trybus, Kathleen M.

    2016-01-01

    Tropomyosin (Tpm) isoforms decorate actin with distinct spatial and temporal localization patterns in cells and thus may function to sort actomyosin processes by modifying the actin track affinity for specific myosin isoforms. We examined the effect of three Tpm isoforms on the ability of myosin Va (myoVa) to engage with actin in vitro in the absence or presence of the cargo adapter melanophilin (Mlph), which links myoVa to Rab27a-melanosomes for in vivo transport. We show that both the myosin motor domain and the cargo adapter Mlph, which has an actin-binding domain that acts as a tether, are sensitive to the Tpm isoform. Actin–Tpm3.1 and actin–Tpm1.8 were equal or better tracks compared to bare actin for myoVa-HMM based on event frequency, run length, and speed. The full-length myoVa-Mlph complex showed high-frequency engagement with actin-Tpm3.1 but not with actin-Tpm1.8. Actin–Tpm4.2 excluded both myoVa-HMM and full-length myoVa-Mlph from productive interactions. Of importance, Tpm3.1 is enriched in the dendritic protrusions and cortical actin of melanocytes, where myoVa-Mlph engages in melanosome transport. These results support the hypothesis that Tpm isoforms constitute an “actin–Tpm code” that allows for spatial and temporal sorting of actomyosin function in the cell. PMID:27535431

  15. A Collapsin Response Mediator Protein 2 Isoform Controls Myosin II-Mediated Cell Migration and Matrix Assembly by Trapping ROCK II

    Science.gov (United States)

    Morgan-Fisher, Marie; Wait, Robin; Couchman, John R.; Wewer, Ulla M.

    2012-01-01

    Collapsin response mediator protein 2 (CRMP-2) is known as a regulator of neuronal polarity and differentiation through microtubule assembly and trafficking. Here, we show that CRMP-2 is ubiquitously expressed and a splice variant (CRMP-2L), which is expressed mainly in epithelial cells among nonneuronal cells, regulates myosin II-mediated cellular functions, including cell migration. While the CRMP-2 short form (CRMP-2S) is recognized as a substrate of the Rho-GTP downstream kinase ROCK in neuronal cells, a CRMP-2 complex containing 2L not only bound the catalytic domain of ROCK II through two binding domains but also trapped and inhibited the kinase. CRMP-2L protein levels profoundly affected haptotactic migration and the actin-myosin cytoskeleton of carcinoma cells as well as nontransformed epithelial cell migration in a ROCK activity-dependent manner. Moreover, the ectopic expression of CRMP-2L but not -2S inhibited fibronectin matrix assembly in fibroblasts. Underlying these responses, CRMP-2L regulated the kinase activity of ROCK II but not ROCK I, independent of GTP-RhoA levels. This study provides a new insight into CRMP-2 as a controller of myosin II-mediated cellular functions through the inhibition of ROCK II in nonneuronal cells. PMID:22431514

  16. Prothrombotic skeletal muscle myosin directly enhances prothrombin activation by binding factors Xa and Va

    Science.gov (United States)

    Deguchi, Hiroshi; Sinha, Ranjeet K.; Marchese, Patrizia; Ruggeri, Zaverio M.; Zilberman-Rudenko, Jevgenia; McCarty, Owen J. T.; Cohen, Mitchell J.

    2016-01-01

    To test the hypothesis that skeletal muscle myosins can directly influence blood coagulation and thrombosis, ex vivo studies of the effects of myosin on thrombogenesis in fresh human blood were conducted. Addition of myosin to blood augmented the thrombotic responses of human blood flowing over collagen-coated surfaces (300 s−1 shear rate). Perfusion of human blood over myosin-coated surfaces also caused fibrin and platelet deposition, evidencing myosin’s thrombogenicity. Myosin markedly enhanced thrombin generation in both platelet-rich plasma and platelet-poor plasma, indicating that myosin promoted thrombin generation in plasma primarily independent of platelets. In purified reaction mixtures composed only of factor Xa, factor Va, prothrombin, and calcium ions, myosin greatly enhanced prothrombinase activity. The Gla domain of factor Xa was not required for myosin’s prothrombinase enhancement. When binding of purified clotting factors to immobilized myosin was monitored using biolayer interferometry, factors Xa and Va each showed favorable binding interactions. Factor Va reduced by 100-fold the apparent Kd of myosin for factor Xa (Kd ∼0.48 nM), primarily by reducing koff, indicating formation of a stable ternary complex of myosin:Xa:Va. In studies to assess possible clinical relevance for this discovery, we found that antimyosin antibodies inhibited thrombin generation in acute trauma patient plasmas more than in control plasmas (P = .0004), implying myosin might contribute to acute trauma coagulopathy. We posit that myosin enhancement of thrombin generation could contribute either to promote hemostasis or to augment thrombosis risk with consequent implications for myosin’s possible contributions to pathophysiology in the setting of acute injuries. PMID:27421960

  17. Myosin individualized: single nucleotide polymorphisms in energy transduction

    Directory of Open Access Journals (Sweden)

    Wieben Eric D

    2010-03-01

    Full Text Available Abstract Background Myosin performs ATP free energy transduction into mechanical work in the motor domain of the myosin heavy chain (MHC. Energy transduction is the definitive systemic feature of the myosin motor performed by coordinating in a time ordered sequence: ATP hydrolysis at the active site, actin affinity modulation at the actin binding site, and the lever-arm rotation of the power stroke. These functions are carried out by several conserved sub-domains within the motor domain. Single nucleotide polymorphisms (SNPs affect the MHC sequence of many isoforms expressed in striated muscle, smooth muscle, and non-muscle tissue. The purpose of this work is to provide a rationale for using SNPs as a functional genomics tool to investigate structurefunction relationships in myosin. In particular, to discover SNP distribution over the conserved sub-domains and surmise what it implies about sub-domain stability and criticality in the energy transduction mechanism. Results An automated routine identifying human nonsynonymous SNP amino acid missense substitutions for any MHC gene mined the NCBI SNP data base. The routine tested 22 MHC genes coding muscle and non-muscle isoforms and identified 89 missense mutation positions in the motor domain with 10 already implicated in heart disease and another 8 lacking sequence homology with a skeletal MHC isoform for which a crystallographic model is available. The remaining 71 SNP substitutions were found to be distributed over MHC with 22 falling outside identified functional sub-domains and 49 in or very near to myosin sub-domains assigned specific crucial functions in energy transduction. The latter includes the active site, the actin binding site, the rigid lever-arm, and regions facilitating their communication. Most MHC isoforms contained SNPs somewhere in the motor domain. Conclusions Several functional-crucial sub-domains are infiltrated by a large number of SNP substitution sites suggesting these

  18. Evolutionary traces decode molecular mechanism behind fast pace of myosin XI

    Directory of Open Access Journals (Sweden)

    Syamaladevi Divya P

    2011-09-01

    Full Text Available Abstract Background Cytoplasmic class XI myosins are the fastest processive motors known. This class functions in high-velocity cytoplasmic streaming in various plant cells from algae to angiosperms. The velocities at which they process are ten times faster than its closest class V homologues. Results To provide sequence determinants and structural rationale for the molecular mechanism of this fast pace myosin, we have compared the sequences from myosin class V and XI through Evolutionary Trace (ET analysis. The current study identifies class-specific residues of myosin XI spread over the actin binding site, ATP binding site and light chain binding neck region. Sequences for ET analysis were accumulated from six plant genomes, using literature based text search and sequence searches, followed by triple validation viz. CDD search, string-based searches and phylogenetic clustering. We have identified nine myosin XI genes in sorghum and seven in grape by sequence searches. Both the plants possess one gene product each belonging to myosin type VIII as well. During this process, we have re-defined the gene boundaries for three sorghum myosin XI genes using fgenesh program. Conclusion Molecular modelling and subsequent analysis of putative interactions involving these class-specific residues suggest a structural basis for the molecular mechanism behind high velocity of plant myosin XI. We propose a model of a more flexible switch I region that contributes to faster ADP release leading to high velocity movement of the algal myosin XI.

  19. The motility of Chara corallina myosin was inhibited reversibly by 2,3-butanedione monoxime (BDM).

    Science.gov (United States)

    Funaki, Keisuke; Nagata, Ayumi; Akimoto, Youka; Shimada, Kiyo; Ito, Kohji; Yamamoto, Keiichi

    2004-09-01

    We studied the effects of 2,3-butanedione monoxime (BDM) on the cytoplasmic streaming of Chara corallina and on the motility of myosin prepared from the same plant to examine whether this reagent really affects the plant class XI myosin. It was found that BDM inhibited both cytoplasmic streaming and the motility of myosin at a very similar concentration range (10-100 mM). BDM introduced directly into tonoplast-free cells also inhibited cytoplasmic streaming. These results suggested that effect of BDM on cytoplasmic streaming was exerted through myosin and not through ion channels at least in Chara corallina, though a very high concentration of BDM was required.

  20. The amino acid sequence of the light chain of Acanthamoeba myosin IC.

    Science.gov (United States)

    Wang, Z Y; Sakai, J; Matsudaira, P T; Baines, I C; Sellers, J R; Hammer, J A; Korn, E D

    1997-06-01

    The amino acid sequence of the light chain of Acanthamoeba myosin IC deduced from the cDNA sequence comprises 149 amino acids with a calculated molecular weight of 16,739. All but the 3 N-terminal residues were also determined by amino acid sequencing of the purified protein, which also showed the N-terminus to be blocked. Phylogenetic analysis shows Acanthamoeba myosin IC light chain to be more similar to the calmodulin subfamily of EF-hand calcium-modulated proteins than to the myosin II essential light chain or regulatory light chain subfamilies. In pairwise comparisons, the myosin IC light chain sequence is most similar to sequences of calmodulins (approximately 50% identical) and a squid calcium-binding protein (approximately 43% identical); the sequence is approximately 37% identical to the calcium-binding essential light chain of Physarum myosin II and approximately 30% identical to the essential light chain of Acanthamoeba myosin II, and the essential light chain and regulatory light chain of Dictyostelium myosin II. The sequence predicts four helix-loop-helix domains with possible calcium-binding sites in domains I and III, suggesting that calcium may affect the activity of this unconventional myosin. This is the first report of the sequence of an unconventional myosin light chain other than calmodulin.

  1. Extracellular matrix-dependent myosin dynamics during G1-S phase cell cycle progression in hepatocytes

    International Nuclear Information System (INIS)

    Bhadriraju, Kiran; Hansen, Linda K.

    2004-01-01

    Cell spreading and proliferation are tightly coupled in anchorage-dependent cells. While adhesion-dependent proliferation signals require an intact actin cytoskeleton, and some of these signals such as ERK activation have been characterized, the role of myosin in spreading and cell cycle progression under different extracellular matrix (ECM) conditions is not known. Studies presented here examine changes in myosin activity in freshly isolated hepatocytes under ECM conditions that promote either proliferation (high fibronectin density) or growth arrest (low fibronectin density). Three different measures were obtained and related to both spreading and cell cycle progression: myosin protein levels and association with cytoskeleton, myosin light chain phosphorylation, and its ATPase activity. During the first 48 h in culture, corresponding with transit through G1 phase, there was a six-fold increase in both myosin protein levels and myosin association with actin cytoskeleton. There was also a steady increase in myosin light chain phosphorylation and ATPase activity with spreading, which did not occur in non-spread, growth-arrested cells on low density of fibronectin. Myosin-inhibiting drugs blocked ERK activation, cyclin D1 expression, and S phase entry. Overexpression of the cell cycle protein cyclin D1 overcame both ECM-dependent and actomyosin-dependent inhibition of DNA synthesis, suggesting that cyclin D1 is a key event downstream of myosin-dependent cell cycle regulation

  2. Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments

    Science.gov (United States)

    Hariadi, R. F.; Sommese, R. F.; Adhikari, A. S.; Taylor, R. E.; Sutton, S.; Spudich, J. A.; Sivaramakrishnan, S.

    2015-08-01

    The sarcomere of muscle is composed of tens of thousands of myosin motors that self-assemble into thick filaments and interact with surrounding actin-based thin filaments in a dense, near-crystalline hexagonal lattice. Together, these actin-myosin interactions enable large-scale movement and force generation, two primary attributes of muscle. Research on isolated fibres has provided considerable insight into the collective properties of muscle, but how actin-myosin interactions are coordinated in an ensemble remains poorly understood. Here, we show that artificial myosin filaments, engineered using a DNA nanotube scaffold, provide precise control over motor number, type and spacing. Using both dimeric myosin V- and myosin VI-labelled nanotubes, we find that neither myosin density nor spacing has a significant effect on the gliding speed of actin filaments. This observation supports a simple model of myosin ensembles as energy reservoirs that buffer individual stochastic events to bring about smooth, continuous motion. Furthermore, gliding speed increases with cross-bridge compliance, but is limited by Brownian effects. As a first step to reconstituting muscle motility, we demonstrate human β-cardiac myosin-driven gliding of actin filaments on DNA nanotubes.

  3. Myosin helical pitch angle as a quantitative imaging biomarker for characterization of cardiac programming in fetal growth restriction measured by polarization second harmonic microscopy

    Science.gov (United States)

    Amat-Roldan, I.; Psilodimitrakopoulos, S.,; Eixarch, E.,; Torre, I.; Wotjas, B.; Crispi, F.; Figueras, F.; Artigas, D.,; Loza-Alvarez, P.; Gratacos, E.,

    2009-07-01

    Fetal growth restriction (FGR) has recently shown a strong association with cardiac programming which predisposes to cardiovascular mortality in adulthood. Polarization Second Harmonic Microscopy can quantify molecular architecture changes with high sensitivity in cardiac myofibrils. In this work, we use myosin helical pitch angle as an example to quantify such alterations related to this high risk population. Importantly, this shows a potential use of the technique as an early diagnostic tool and an alternative method to understand pathophysiological processes.

  4. The Charm and Beauty of Strong Interactions

    Science.gov (United States)

    El-Bennich, Bruno

    2018-01-01

    We briefly review common features and overlapping issues in hadron and flavor physics focussing on continuum QCD approaches to heavy bound states, their mass spectrum and weak decay constants in different strong interaction models.

  5. Quantification and localization of phosphorylated myosin I isoforms in Acanthamoeba castellanii.

    Science.gov (United States)

    Baines, I C; Corigliano-Murphy, A; Korn, E D

    1995-08-01

    The actin-activated Mg(2+)-ATPase activities of the three myosin I isoforms in Acanthamoeba castellanii are significantly expressed only after phosphorylation of a single site in the myosin I heavy chain. Synthetic phosphorylated and unphosphorylated peptides corresponding to the phosphorylation site sequences, which differ for the three myosin I isoforms, were used to raise isoform-specific antibodies that recognized only the phosphorylated myosin I or the total myosin I isoform (phosphorylated and unphosphorylated), respectively. With these antisera, the amounts of total and phosphorylated isoform were quantified, the phosphomyosin I isoforms localized, and the compartmental distribution of the phosphomyosin isoforms determined. Myosin IA, which was almost entirely in the actin-rich cortex, was 70-100% phosphorylated and particularly enriched under phagocytic cups. Myosins IB and IC were predominantly associated with plasma membranes and large vacuole membranes, where they were only 10-20% phosphorylated, whereas cytoplasmic myosins IB and IC, like cytoplasmic myosin IA, were mostly phosphorylated (60-100%). Moreover, phosphomyosin IB was concentrated in actively motile regions of the plasma membrane. More than 20-fold more phosphomyosin IC and 10-fold more F-actin were associated with the membranes of contracting contractile vacuoles (CV) than of filling CVs. As the total amount of CV-associated myosin IC remained constant, it must be phosphorylated at the start of CV contraction. These data extend previous proposals for the specific functions of myosin I isozymes in Acanthamoeba (Baines, I.C., H. Brzeska, and E.D. Korn. 1992. J. Cell Biol. 119: 1193-1203): phosphomyosin IA in phagocytosis, phosphomyosin IB in phagocytosis and pinocytosis, and phosphomyosin IC in contraction of the CV.

  6. Identification of myosin XI receptors in Arabidopsis defines a distinct class of transport vesicles.

    Science.gov (United States)

    Peremyslov, Valera V; Morgun, Eva A; Kurth, Elizabeth G; Makarova, Kira S; Koonin, Eugene V; Dolja, Valerian V

    2013-08-01

    To characterize the mechanism through which myosin XI-K attaches to its principal endomembrane cargo, a yeast two-hybrid library of Arabidopsis thaliana cDNAs was screened using the myosin cargo binding domain as bait. This screen identified two previously uncharacterized transmembrane proteins (hereinafter myosin binding proteins or MyoB1/2) that share a myosin binding, conserved domain of unknown function 593 (DUF593). Additional screens revealed that MyoB1/2 also bind myosin XI-1, whereas myosin XI-I interacts with the distantly related MyoB7. The in vivo interactions of MyoB1/2 with myosin XI-K were confirmed by immunoprecipitation and colocalization analyses. In epidermal cells, the yellow fluorescent protein-tagged MyoB1/2 localize to vesicles that traffic in a myosin XI-dependent manner. Similar to myosin XI-K, MyoB1/2 accumulate in the tip-growing domain of elongating root hairs. Gene knockout analysis demonstrated that functional cooperation between myosin XI-K and MyoB proteins is required for proper plant development. Unexpectedly, the MyoB1-containing vesicles did not correspond to brefeldin A-sensitive Golgi and post-Golgi or prevacuolar compartments and did not colocalize with known exocytic or endosomal compartments. Phylogenomic analysis suggests that DUF593 emerged in primitive land plants and founded a multigene family that is conserved in all flowering plants. Collectively, these findings indicate that MyoB are membrane-anchored myosin receptors that define a distinct, plant-specific transport vesicle compartment.

  7. Myosin Va is developmentally regulated and expressed in the human cerebellum from birth to old age

    Directory of Open Access Journals (Sweden)

    C.C.R. Souza

    2013-02-01

    Full Text Available Myosin Va functions as a processive, actin-based motor molecule highly enriched in the nervous system, which transports and/or tethers organelles, vesicles, and mRNA and protein translation machinery. Mutation of myosin Va leads to Griscelli disease that is associated with severe neurological deficits and a short life span. Despite playing a critical role in development, the expression of myosin Va in the central nervous system throughout the human life span has not been reported. To address this issue, the cerebellar expression of myosin Va from newborns to elderly humans was studied by immunohistochemistry using an affinity-purified anti-myosin Va antibody. Myosin Va was expressed at all ages from the 10th postnatal day to the 98th year of life, in molecular, Purkinje and granular cerebellar layers. Cerebellar myosin Va expression did not differ essentially in localization or intensity from childhood to old age, except during the postnatal developmental period. Structures resembling granules and climbing fibers in Purkinje cells were deeply stained. In dentate neurons, long processes were deeply stained by anti-myosin Va, as were punctate nuclear structures. During the first postnatal year, myosin Va was differentially expressed in the external granular layer (EGL. In the EGL, proliferating prospective granule cells were not stained by anti-myosin Va antibody. In contrast, premigratory granule cells in the EGL stained moderately. Granule cells exhibiting a migratory profile in the molecular layer were also moderately stained. In conclusion, neuronal myosin Va is developmentally regulated, and appears to be required for cerebellar function from early postnatal life to senescence.

  8. Validation of EMP bounds

    Energy Technology Data Exchange (ETDEWEB)

    Warne, L.K.; Merewether, K.O.; Chen, K.C.; Jorgenson, R.E.; Morris, M.E.; Solberg, J.E.; Lewis, J.G. [Sandia National Labs., Albuquerque, NM (United States); Derr, W. [Derr Enterprises, Albuquerque, NM (United States)

    1996-07-01

    Test data on canonical weapon-like fixtures are used to validate previously developed analytical bounding results. The test fixtures were constructed to simulate (but be slightly worse than) weapon ports of entry but have known geometries (and electrical points of contact). The exterior of the test fixtures exhibited exterior resonant enhancement of the incident fields at the ports of entry with magnitudes equal to those of weapon geometries. The interior consisted of loaded transmission lines adjusted to maximize received energy or voltage but incorporating practical weapon geometrical constraints. New analytical results are also presented for bounding the energies associated with multiple bolt joints and for bounding the exterior resonant enhancement of the exciting fields.

  9. Massive Galileon positivity bounds

    Science.gov (United States)

    de Rham, Claudia; Melville, Scott; Tolley, Andrew J.; Zhou, Shuang-Yong

    2017-09-01

    The EFT coefficients in any gapped, scalar, Lorentz invariant field theory must satisfy positivity requirements if there is to exist a local, analytic Wilsonian UV completion. We apply these bounds to the tree level scattering amplitudes for a massive Galileon. The addition of a mass term, which does not spoil the non-renormalization theorem of the Galileon and preserves the Galileon symmetry at loop level, is necessary to satisfy the lowest order positivity bound. We further show that a careful choice of successively higher derivative corrections are necessary to satisfy the higher order positivity bounds. There is then no obstruction to a local UV completion from considerations of tree level 2-to-2 scattering alone. To demonstrate this we give an explicit example of such a UV completion.

  10. Properties of Water Bound in Hydrogels

    Directory of Open Access Journals (Sweden)

    Vladimir M. Gun’ko

    2017-10-01

    Full Text Available In this review, the importance of water in hydrogel (HG properties and structure is analyzed. A variety of methods such as 1H NMR (nuclear magnetic resonance, DSC (differential scanning calorimetry, XRD (X-ray powder diffraction, dielectric relaxation spectroscopy, thermally stimulated depolarization current, quasi-elastic neutron scattering, rheometry, diffusion, adsorption, infrared spectroscopy are used to study water in HG. The state of HG water is rather non-uniform. According to thermodynamic features of water in HG, some of it is non-freezing and strongly bound, another fraction is freezing and weakly bound, and the third fraction is non-bound, free water freezing at 0 °C. According to structural features of water in HG, it can be divided into two fractions with strongly associated and weakly associated waters. The properties of the water in HG depend also on the amounts and types of solutes, pH, salinity, structural features of HG functionalities.

  11. Immunohistochemical localization of smooth muscle myosin in human spleen, lymph node, and other lymphoid tissues. Unique staining patterns in splenic white pulp and sinuses, lymphoid follicles, and certain vasculature, with ultrastructural correlations.

    Science.gov (United States)

    Pinkus, G. S.; Warhol, M. J.; O'Connor, E. M.; Etheridge, C. L.; Fujiwara, K.

    1986-01-01

    The anatomic distribution of smooth muscle myosin, a contractile protein, was determined in a variety of lymphoid tissues (spleen, lymph nodes, tonsils) with the use of highly specific rabbit antibodies to human uterine smooth muscle myosin and an indirect immunoperoxidase technique. In the spleen, in addition to the anticipated immunoreactivity in the walls of arteries, veins, splenic capsule, and trabeculas, other staining patterns were observed. Smooth muscle myosin-containing cells which comprised the adventitia of the trabecular arteries appeared continuous with myosin-containing reticular cells of the white pulp. The latter cells assumed a circumferential pattern within the periarteriolar lymphoid sheaths, then blended delicately with the red pulp at the marginal zone. Ultrastructurally, immunogold techniques demonstrated that smooth muscle myosin in these cells was localized to cytoplasmic filaments. Within the red pulp, a different and distinct staining pattern was observed for the splenic sinuses. Short, regular, orderly, and repetitive bands of immunoreactivity, aligned parallel to the long axis of the sinus, extended between contiguous ring fibers. By immunoelectron microscopy these structures corresponded to distinct bundles of filaments in the endothelial lining cells of the splenic sinuses. Factor VIII associated antigen was also identified in the splenic lining cells in cryostat and paraffin sections, and ultrastructurally. Within the red pulp of the spleen, the sheaths of sheathed capillaries also revealed strong immunoreactivity for smooth muscle myosin. Other sites of immunohistochemical localization of smooth muscle myosin included dendritic reticulum cells present in reactive follicles and in nodular non-Hodgkin's lymphomas. Certain vascular structures, specifically sinus lining cells and Schweigger-Seidel capillary sheaths of the spleen and postcapillary venules of lymph nodes and tonsils, coexpressed smooth muscle myosin and Factor VIII

  12. Myosin VIII regulates protonemal patterning and developmental timing in the moss Physcomitrella patens.

    Science.gov (United States)

    Wu, Shu-Zon; Ritchie, Julie A; Pan, Ai-Hong; Quatrano, Ralph S; Bezanilla, Magdalena

    2011-09-01

    Plants have two classes of myosins. While recent work has focused on class XI myosins showing that myosin XI is responsible for organelle motility and cytoplasmic streaming, much less is known about the role of myosin VIII in plant growth and development. We have used a combination of RNAi and insertional knockouts to probe myosin VIII function in the moss Physcomitrella patens. We isolated Δmyo8ABCDE plants demonstrating that myosin VIII is not required for plant viability. However, myosin VIII mutants are smaller than wild-type plants in part due to a defect in cell size. Additionally, Δmyo8ABCDE plants produce more side branches and form gametophores much earlier than wild-type plants. In the absence of nutrient media, Δmyo8ABCDE plants exhibit significant protonemal patterning defects, including highly curved protonemal filaments, morphologically defective side branches, as well as an increase in the number of branches. Exogenous auxin partially rescues protonemal defects in Δmyo8ABCDE plants grown in the absence of nutrients. This result, together with defects in protonemal branching, smaller caulonemal cells, and accelerated development in the Δmyo8ABCDE plants, suggests that myosin VIII is involved in hormone homeostasis in P. patens.

  13. Kinetic signatures of myosin-5B, the motor involved in microvillus inclusion disease.

    Science.gov (United States)

    Heissler, Sarah M; Chinthalapudi, Krishna; Sellers, James R

    2017-11-03

    Myosin-5B is a ubiquitous molecular motor that transports cargo vesicles of the endomembrane system in intracellular recycling pathways. Myosin-5B malfunction causes the congenital enteropathy microvillus inclusion disease, underlining its importance in cellular homeostasis. Here we describe the interaction of myosin-5B with F-actin, nucleotides, and the pyrazolopyrimidine compound myoVin-1. We show that single-headed myosin-5B is an intermediate duty ratio motor with a kinetic ATPase cycle that is rate-limited by the release of phosphate. The presence of a second head generates strain and gating in the myosin-5B dimer that alters the kinetic signature by reducing the actin-activated ADP release rate to become rate-limiting. This kinetic transition into a high-duty ratio motor is a prerequisite for the proposed transport function of myosin-5B in cellular recycling pathways. Moreover, we show that the small molecule compound myoVin-1 inhibits the enzymatic and functional activity of myosin-5B in vitro Partial inhibition of the actin-activated steady-state ATPase activity and sliding velocity suggests that caution should be used when probing the effect of myoVin-1 on myosin-5-dependent transport processes in cells.

  14. Reduction in beta-myosin heavy chains in stunned myocardium as assessed by nondenaturing gel electrophoresis.

    Science.gov (United States)

    Garcia, S C; Pomblum, V J; Gams, E; Rupp, H; Schipke, J D

    2007-09-01

    Myosin plays a key role in the structure and function of cardiac muscle. Three myosin isoenzymes (V(1), V(2), and V(3)) with different ATPase activities have been identified in mammalian ventricles based on their heavy chain constituents. The relative amount of myosin isoenzymes changes under physiological and pathological conditions. Until now, myosin isoenzymes have frequently been determined using either tube gel (nondenaturing) polyacrylamide gel electrophoresis (PAGE), or gradient or uniform sodium dodecyl sulfate (denaturing) PAGE. Both methods have disadvantages, e.g., a long running time. We developed, therefore, a uniform, nondenaturing PAGE with slab minigel format for analyzing the myosin isoenzymes in normoxic and stunned rabbit hearts. In normoxic hearts of adult rabbits, V(3) predominated over V(1) (46 vs 41%). In turn, in the stunned hearts, V(1) predominated over V(3) (70 vs 30%), and the heterodimeric V(2) was not anymore detectable. This alteration appears to result from a selective loss of myosin heavy chain (MHC)-beta. In parallel, the biochemical markers troponin I and creatine kinase were increased in the stunned hearts. We suggest that alterations of myosin isoenzymes in stunned myocardium can be monitored with native PAGE. The present analysis of myosin isoenzyme appears thus as a new tool for evaluating defects in MHC dimer formation in postischemic hearts.

  15. Nuclear myosin is ubiquitously expressed and evolutionary conserved in vertebrates

    Czech Academy of Sciences Publication Activity Database

    Kahle, Michal; Přidalová, Jarmila; Špaček, M.; Dzijak, Rastislav; Hozák, Pavel

    2007-01-01

    Roč. 127, č. 2 (2007), s. 139-184 ISSN 0948-6143 R&D Projects: GA ČR GA204/04/0108; GA AV ČR IAA5039202; GA MŠk LC545; GA ČR GD204/05/H023 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z50520514 Keywords : Nuclear myosin I * Transcription * Chromatin Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.893, year: 2007

  16. Bounded variation and around

    CERN Document Server

    Appell, Jürgen; Merentes Díaz, Nelson José

    2013-01-01

    This monographis a self-contained exposition of the definition and properties of functionsof bounded variation and their various generalizations; the analytical properties of nonlinear composition operators in spaces of such functions; applications to Fourier analysis, nonlinear integral equations, and boundary value problems. The book is written for non-specialists. Every chapter closes with a list of exercises and open problems.

  17. Born Level Bound States

    Science.gov (United States)

    Hoyer, Paul

    2017-05-01

    Bound state poles in the S-matrix of perturbative QED are generated by the divergence of the expansion in α . The perturbative corrections are necessarily singular when expanding around free, {O}( α ^0 ) in and out states that have no overlap with finite-sized atomic wave functions. Nevertheless, measurables such as binding energies do have well-behaved expansions in powers of α (and log α ). It is desirable to formulate the concept of "lowest order" for gauge theory bound states such that higher order corrections vanish in the α → 0 limit. This may allow to determine a lowest order term for QCD hadrons which incorporates essential features such as confinement and chiral symmetry breaking, and thus can serve as the starting point of a useful perturbative expansion. I discuss a "Born" (no loop, lowest order in \\hbar ) approximation. Born level states are bound by gauge fields which satisfy the classical field equations. Gauss' law determines a distinct field A^0({\\varvec{x}}) for each instantaneous position of the charges. A Poincaré covariant boundary condition for the gluon field leads to a confining potential for q\\bar{q} and qqq states. In frames where the bound state is in motion the classical gauge field is obtained by a Lorentz boost of the rest frame field.

  18. Bounded Brownian Motion

    Directory of Open Access Journals (Sweden)

    Peter Carr

    2017-11-01

    Full Text Available Diffusions are widely used in finance due to their tractability. Driftless diffusions are needed to describe ratios of asset prices under a martingale measure. We provide a simple example of a tractable driftless diffusion which also has a bounded state space.

  19. Modeling Hand-Over-Hand and Inchworm Steps in Myosin VI

    Science.gov (United States)

    Jack, Amanda; Lowe, Ian; Tehver, Riina

    Myosin VI is a molecular motor protein that moves along actin filaments to transport cargo within a cell. There is much experimental evidence that the myosin VI dimer moves ``hand-over-hand'' along actin; however, recent experiments suggest that the protein can also move via an ``inchworm'' mechanism. We created a mechanochemical kinetic model to predict myosin VI's behavior under different ATP, ADP, and force conditions, taking these alternative mechanisms into account. Our model's calculations agree well with experimental results and can also be used to predict myosin VI's behavior outside experimentally tested regimes, such as under forward force. We also predict an optimized motor function for the protein around physiological (-2 pN) load and anchoring under -3 pN load. By using our model to predict myosin VI's response to environmental change, we can gain insight into the behavior of a protein that can be difficult to observe experimentally.

  20. Competition between Coiled-Coil Structures and the Impact on Myosin-10 Bundle Selection.

    Science.gov (United States)

    Vavra, Kevin C; Xia, Youlin; Rock, Ronald S

    2016-06-07

    Coiled-coil fusions are a useful approach to enforce dimerization in protein engineering. However, the final structures of coiled-coil fusion proteins have received relatively little attention. Here, we determine the structural outcome of adjacent parallel and antiparallel coiled coils. The targets are coiled coils that stabilize myosin-10 in single-molecule biophysical studies. We reveal the solution structure of a short, antiparallel, myosin-10 coiled-coil fused to the parallel GCN4-p1 coiled coil. Surprisingly, this structure is a continuous, antiparallel coiled coil where GCN4-p1 pairs with myosin-10 rather than itself. We also show that longer myosin-10 segments in these parallel/antiparallel fusions are dynamic and do not fold cooperatively. Our data resolve conflicting results on myosin-10 selection of actin filament bundles, demonstrating the importance of understanding coiled-coil orientation and stability. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Life without double-headed non-muscle myosin II motor proteins

    Directory of Open Access Journals (Sweden)

    Venkaiah eBetapudi

    2014-07-01

    Full Text Available Non-muscle myosin II motor proteins (myosin IIA, myosin IIB, and myosin IIC belong to a class of molecular motor proteins that are known to transduce cellular free-energy into biological work more efficiently than man-made combustion engines. Nature has given a single myosin II motor protein for lower eukaryotes and multiple for mammals but none for plants in order to provide impetus for their life. These specialized nanomachines drive cellular activities necessary for embryogenesis, organogenesis, and immunity. However, these multifunctional myosin II motor proteins are believed to go awry due to unknown reasons and contribute for the onset and progression of many autosomal-dominant disorders, cataract, deafness, infertility, cancer, kidney, neuronal, and inflammatory diseases. Many pathogens like HIV, Dengue, hepatitis C, and Lymphoma viruses as well as Salmonella and Mycobacteria are now known to take hostage of these dedicated myosin II motor proteins for their efficient pathogenesis. Even after four decades since their discovery, we still have a limited knowledge of how these motor proteins drive cell migration and cytokinesis. We need to enrich our current knowledge on these fundamental cellular processes and develop novel therapeutic strategies to fix mutated myosin II motor proteins in pathological conditions. This is the time to think how to relieve the hijacked myosins from pathogens in order to provide a renewed impetus for patients’ life. Understanding how to steer these molecular motors in proliferating and differentiating stem cells will improve stem cell based-therapeutics development. Given the plethora of cellular activities non-muscle myosin motor proteins are involved in, their importance is apparent for human life.

  2. Morphological, histochemical, and myosin isoform analysis of the diaphragm of adult horses, Equus caballus.

    Science.gov (United States)

    Cobb, M A; Schutt, W A; Hermanson, J W

    1994-03-01

    The horse provides an interesting model for study of the structure and function of the mammalian diaphragm. Multiple regions of diaphragm from seven adult horses were prepared for histochemistry, immunocytochemistry, myosin heavy chain electrophoresis, and native myosin electrophoresis. Two additional adults were dissected to demonstrate myofiber and central tendon morphology and stained for acetylcholinesterase to demonstrate motor endplates. All regions of the adult diaphragm were histochemically characterized by a preponderance of type I fibers with some type IIa fibers. Type IIb fibers were absent in all adult specimens. Myosin heavy chain electrophoresis supported the histochemical study: two isoform bands were present on SDS gels that comigrated at the same rate as rat type I and IIa myosin heavy chain isoforms. No isoform was determined to comigrate with rat type IIb heavy chain isoforms. Native myosin isoform analysis revealed two isoforms that comigrated with rat FM-4 and FM-3 (FM = fast myosin) and two isoforms that comigrated with rat SM-1 and SM-2 (SM = slow myosin) isoforms. In some samples, a third slow native myosin isoform was observed that comigrated at the same rate as the SM-3 of the equine biceps brachii muscle. This doublet (or "triplet") of slow isoforms is unique to some horse muscles compared with other adult animals studied. It is not known if these multiple slow native myosin isoforms confer some functional advantage to the equine muscles. The adult equine diaphragm also differs in its morphology by having a large central tendon compared to that in other mammals, and is predominantly slow in fiber type and myosin isoform composition.

  3. Life without double-headed non-muscle myosin II motor proteins

    Science.gov (United States)

    Betapudi, Venkaiah

    2014-07-01

    Non-muscle myosin II motor proteins (myosin IIA, myosin IIB, and myosin IIC) belong to a class of molecular motor proteins that are known to transduce cellular free-energy into biological work more efficiently than man-made combustion engines. Nature has given a single myosin II motor protein for lower eukaryotes and multiple for mammals but none for plants in order to provide impetus for their life. These specialized nanomachines drive cellular activities necessary for embryogenesis, organogenesis, and immunity. However, these multifunctional myosin II motor proteins are believed to go awry due to unknown reasons and contribute for the onset and progression of many autosomal-dominant disorders, cataract, deafness, infertility, cancer, kidney, neuronal, and inflammatory diseases. Many pathogens like HIV, Dengue, hepatitis C, and Lymphoma viruses as well as Salmonella and Mycobacteria are now known to take hostage of these dedicated myosin II motor proteins for their efficient pathogenesis. Even after four decades since their discovery, we still have a limited knowledge of how these motor proteins drive cell migration and cytokinesis. We need to enrich our current knowledge on these fundamental cellular processes and develop novel therapeutic strategies to fix mutated myosin II motor proteins in pathological conditions. This is the time to think how to relieve the hijacked myosins from pathogens in order to provide a renewed impetus for patients’ life. Understanding how to steer these molecular motors in proliferating and differentiating stem cells will improve stem cell based-therapeutics development. Given the plethora of cellular activities non-muscle myosin motor proteins are involved in, their importance is apparent for human life.

  4. Dwell time distributions of the molecular motor myosin V.

    Directory of Open Access Journals (Sweden)

    Veronika Bierbaum

    Full Text Available The dwell times between two successive steps of the two-headed molecular motor myosin V are governed by non-exponential distributions. These distributions have been determined experimentally for various control parameters such as nucleotide concentrations and external load force. First, we use a simplified network representation to determine the dwell time distributions of myosin V, with the associated dynamics described by a Markov process on networks with absorbing boundaries. Our approach provides a direct relation between the motor's chemical kinetics and its stepping properties. In the absence of an external load, the theoretical distributions quantitatively agree with experimental findings for various nucleotide concentrations. Second, using a more complex branched network, which includes ADP release from the leading head, we are able to elucidate the motor's gating effect. This effect is caused by an asymmetry in the chemical properties of the leading and the trailing head of the motor molecule. In the case of an external load acting on the motor, the corresponding dwell time distributions reveal details about the motor's backsteps.

  5. Discoidin Domain Receptor 1 Mediates Myosin-Dependent Collagen Contraction

    Directory of Open Access Journals (Sweden)

    Nuno M. Coelho

    2017-02-01

    Full Text Available Discoidin domain receptor 1 (DDR1 is a tyrosine kinase collagen adhesion receptor that mediates cell migration through association with non-muscle myosin IIA (NMIIA. Because DDR1 is implicated in cancer fibrosis, we hypothesized that DDR1 interacts with NMIIA to enable collagen compaction by traction forces. Mechanical splinting of rat dermal wounds increased DDR1 expression and collagen alignment. In periodontal ligament of DDR1 knockout mice, collagen mechanical reorganization was reduced >30%. Similarly, cultured cells with DDR1 knockdown or expressing kinase-deficient DDR1d showed 50% reduction of aligned collagen. Tractional remodeling of collagen was dependent on DDR1 clustering, activation, and interaction of the DDR1 C-terminal kinase domain with NMIIA filaments. Collagen remodeling by traction forces, DDR1 tyrosine phosphorylation, and myosin light chain phosphorylation were increased on stiff versus soft substrates. Thus, DDR1 clustering, activation, and interaction with NMIIA filaments enhance the collagen tractional remodeling that is important for collagen compaction in fibrosis.

  6. Learning within bounds and dream sleep

    Science.gov (United States)

    Geszti, T.; Pazmandi, F.

    1987-12-01

    In a bounded-synapses version of Hopfield's model (1984) for neural networks the quasienergy of a given memory, which is approximately equal to the depth of the corresponding energy well is calculated exactly by treating the change of a synaptic strength on learning as a random walk within bounds. Attractors corresponding to stored memories are found to be considerably flattened before serious retrieval errors arise. This allows dream sleep to be interpreted as random recall and relearning of fresh strong memories, in order to stack them on top of weak incidental memory imprints of a day.

  7. Bounded Tamper Resilience

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Faust, Sebastian; Mukherjee, Pratyay

    2013-01-01

    -free information) which can be used to refresh the secret key. We believe that bounded tampering is a meaningful and interesting alternative to avoid known impossibility results and can provide important insights into the security of existing standard cryptographic schemes.......Related key attacks (RKAs) are powerful cryptanalytic attacks where an adversary can change the secret key and observe the effect of such changes at the output. The state of the art in RKA security protects against an a-priori unbounded number of certain algebraic induced key relations, e.......g., affine functions or polynomials of bounded degree. In this work, we show that it is possible to go beyond the algebraic barrier and achieve security against arbitrary key relations, by restricting the number of tampering queries the adversary is allowed to ask for. The latter restriction is necessary...

  8. Bound Exciton Complexes

    Science.gov (United States)

    Meyer, B. K.

    In the preceding chapter, we concentrated on the properties of free excitons. These free excitons may move through the sample and hit a trap, a nonradiative or a radiative recombination center. At low temperatures, the latter case gives rise to either deep center luminescence, mentioned in Sect. 7.1 and discussed in detail in Chap. 9, or to the luminescence of bound exciton complexes (BE or BEC). The chapter continues with the most prominent of these BECs, namely A-excitons bound to neutral donors. The next aspects are the more weakly BEs at ionized donors. The Sect. 7.4 treats the binding or localization energies of BEC from a theoretical point of view, while Sect. 7.5 is dedicated to excited states of BECs, which contain either holes from deeper valence bands or an envelope function with higher quantum numbers. The last section is devoted to donor-acceptor pair transitions. There is no section devoted specifically to excitons bound to neutral acceptors, because this topic is still partly controversially discussed. Instead, information on these A0X complexes is scattered over the whole chapter, however, with some special emphasis seen in Sects. 7.1, 7.4, and 7.5.

  9. Pharmacological activation of myosin II paralogs to correct cell mechanics defects.

    Science.gov (United States)

    Surcel, Alexandra; Ng, Win Pin; West-Foyle, Hoku; Zhu, Qingfeng; Ren, Yixin; Avery, Lindsay B; Krenc, Agata K; Meyers, David J; Rock, Ronald S; Anders, Robert A; Freel Meyers, Caren L; Robinson, Douglas N

    2015-02-03

    Current approaches to cancer treatment focus on targeting signal transduction pathways. Here, we develop an alternative system for targeting cell mechanics for the discovery of novel therapeutics. We designed a live-cell, high-throughput chemical screen to identify mechanical modulators. We characterized 4-hydroxyacetophenone (4-HAP), which enhances the cortical localization of the mechanoenzyme myosin II, independent of myosin heavy-chain phosphorylation, thus increasing cellular cortical tension. To shift cell mechanics, 4-HAP requires myosin II, including its full power stroke, specifically activating human myosin IIB (MYH10) and human myosin IIC (MYH14), but not human myosin IIA (MYH9). We further demonstrated that invasive pancreatic cancer cells are more deformable than normal pancreatic ductal epithelial cells, a mechanical profile that was partially corrected with 4-HAP, which also decreased the invasion and migration of these cancer cells. Overall, 4-HAP modifies nonmuscle myosin II-based cell mechanics across phylogeny and disease states and provides proof of concept that cell mechanics offer a rich drug target space, allowing for possible corrective modulation of tumor cell behavior.

  10. Mutations in the SH1 helix alter the thermal properties of myosin II.

    Science.gov (United States)

    Shibata, Kotomi; Koyama, Tsubasa; Inde, Shohei; Iwai, Sosuke; Chaen, Shigeru

    2017-01-01

    The myosin II SH1 helix is a joint that links the converter subdomain to the rest of the myosin motor domain and possibly plays a key role in the arrangement of the converter/lever arm. Several point mutations within the SH1 helix in human myosin IIs have been shown to cause diseases. To reveal whether these SH1 helix mutations affect not only motile activities but also thermal properties of myosin II, here we introduced the E683K or R686C point mutation into the SH1 helix in Dictyostelium myosin II. Thermal inactivation as well as thermal aggregation rates of these mutant proteins demonstrated that these mutations decreased the thermal stability of myosin II. Temperature dependence of sliding velocities of actin filaments showed that these mutations also reduced the activation energy of a rate-limiting process involved in actin movement. Given that these mutations are likely to alter coupling between the subdomains, and thus their thermal fluctuations, we propose that the SH1 helix is a key structural element that determines the flexibility and thermal properties of the myosin motor. These characteristics of the SH1 helix may contribute to the pathogenesis of the human diseases caused by mutations within this structural element.

  11. Myosin-Va and Dynamic Actin Oppose Microtubules to Drive Long-Range Organelle Transport

    Science.gov (United States)

    Evans, Richard D.; Robinson, Christopher; Briggs, Deborah A.; Tooth, David J.; Ramalho, Jose S.; Cantero, Marta; Montoliu, Lluis; Patel, Shyamal; Sviderskaya, Elena V.; Hume, Alistair N.

    2014-01-01

    Summary In animal cells, microtubule and actin tracks and their associated motors (dynein, kinesin, and myosin) are thought to regulate long- and short-range transport, respectively [1–8]. Consistent with this, microtubules extend from the perinuclear centrosome to the plasma membrane and allow bidirectional cargo transport over long distances (>1 μm). In contrast, actin often comprises a complex network of short randomly oriented filaments, suggesting that myosin motors move cargo short distances. These observations underpin the “highways and local roads” model for transport along microtubule and actin tracks [2]. The “cooperative capture” model exemplifies this view and suggests that melanosome distribution in melanocyte dendrites is maintained by long-range transport on microtubules followed by actin/myosin-Va-dependent tethering [5, 9]. In this study, we used cell normalization technology to quantitatively examine the contribution of microtubules and actin/myosin-Va to organelle distribution in melanocytes. Surprisingly, our results indicate that microtubules are essential for centripetal, but not centrifugal, transport. Instead, we find that microtubules retard a centrifugal transport process that is dependent on myosin-Va and a population of dynamic F-actin. Functional analysis of mutant proteins indicates that myosin-Va works as a transporter dispersing melanosomes along actin tracks whose +/barbed ends are oriented toward the plasma membrane. Overall, our data highlight the role of myosin-Va and actin in transport, and not tethering, and suggest a new model in which organelle distribution is determined by the balance between microtubule-dependent centripetal and myosin-Va/actin-dependent centrifugal transport. These observations appear to be consistent with evidence coming from other systems showing that actin/myosin networks can drive long-distance organelle transport and positioning [10, 11]. PMID:25065759

  12. Yukawa Bound States and Their LHC Phenomenology

    Directory of Open Access Journals (Sweden)

    Enkhbat Tsedenbaljir

    2013-01-01

    Full Text Available We present the current status on the possible bound states of extra generation quarks. These include phenomenology and search strategy at the LHC. If chiral fourth-generation quarks do exist their strong Yukawa couplings, implied by current experimental lower bound on their masses, may lead to formation of bound states. Due to nearly degenerate 4G masses suggested by Precision Electroweak Test one can employ “heavy isospin” symmetry to classify possible spectrum. Among these states, the color-octet isosinglet vector ω 8 is the easiest to be produced at the LHC. The discovery potential and corresponding decay channels are covered in this paper. With possible light Higgs at ~125 GeV two-Higgs doublet version is briefly discussed.

  13. Blog life: Entropy Bound

    Science.gov (United States)

    Steinberg, Peter

    2008-06-01

    Who is the blog written by? Peter Steinberg is a nuclear physicist at the Brookhaven National Laboratory in New York, US. He is acting project manager of the PHOBOS experiment, which used Brookhaven's Relativistic Heavy Ion Collider (RHIC) to search for unusual events produced during collisions between gold nuclei. He is also involved with the PHENIX experiment, which seeks to discover a new state of matter known as the quark-gluon plasma. In addition to his own blog Entropy Bound, Steinberg is currently blogging on a website that was set up last year to publicize the involvement of US scientists with the Large Hadron Collider (LHC) at CERN.

  14. Regularity of Bound States

    DEFF Research Database (Denmark)

    Faupin, Jeremy; Møller, Jacob Schach; Skibsted, Erik

    2011-01-01

    We study regularity of bound states pertaining to embedded eigenvalues of a self-adjoint operator H, with respect to an auxiliary operator A that is conjugate to H in the sense of Mourre. We work within the framework of singular Mourre theory which enables us to deal with confined massless Pauli–......–Fierz models, our primary example, and many-body AC-Stark Hamiltonians. In the simpler context of regular Mourre theory, our results boil down to an improvement of results obtained recently in [8, 9]....

  15. Sarcomere lattice geometry influences cooperative myosin binding in muscle.

    Directory of Open Access Journals (Sweden)

    Bertrand C W Tanner

    2007-07-01

    Full Text Available In muscle, force emerges from myosin binding with actin (forming a cross-bridge. This actomyosin binding depends upon myofilament geometry, kinetics of thin-filament Ca(2+ activation, and kinetics of cross-bridge cycling. Binding occurs within a compliant network of protein filaments where there is mechanical coupling between myosins along the thick-filament backbone and between actin monomers along the thin filament. Such mechanical coupling precludes using ordinary differential equation models when examining the effects of lattice geometry, kinetics, or compliance on force production. This study uses two stochastically driven, spatially explicit models to predict levels of cross-bridge binding, force, thin-filament Ca(2+ activation, and ATP utilization. One model incorporates the 2-to-1 ratio of thin to thick filaments of vertebrate striated muscle (multi-filament model, while the other comprises only one thick and one thin filament (two-filament model. Simulations comparing these models show that the multi-filament predictions of force, fractional cross-bridge binding, and cross-bridge turnover are more consistent with published experimental values. Furthermore, the values predicted by the multi-filament model are greater than those values predicted by the two-filament model. These increases are larger than the relative increase of potential inter-filament interactions in the multi-filament model versus the two-filament model. This amplification of coordinated cross-bridge binding and cycling indicates a mechanism of cooperativity that depends on sarcomere lattice geometry, specifically the ratio and arrangement of myofilaments.

  16. Atom collisions in a strong electromagnetic field

    International Nuclear Information System (INIS)

    Smirnov, V.S.; Chaplik, A.V.

    1976-01-01

    It is shown that the long-range part of interatomic interaction is considerably altered in a strong electromagnetic field. Instead of the van der Waals law the potential asymptote can best be described by a dipole-dipole R -3 law. Impact broadening and the line shift in a strong nonresonant field are calculated. The possibility of bound states of two atoms being formed in a strong light field is discussed

  17. Myosin-V Induces Cargo Immobilization and Clustering at the Axon Initial Segment

    Directory of Open Access Journals (Sweden)

    Anne F. J. Janssen

    2017-08-01

    Full Text Available The selective transport of different cargoes into axons and dendrites underlies the polarized organization of the neuron. Although it has become clear that the combined activity of different motors determines the destination and selectivity of transport, little is known about the mechanistic details of motor cooperation. For example, the exact role of myosin-V in opposing microtubule-based axon entries has remained unclear. Here we use two orthogonal chemically-induced heterodimerization systems to independently recruit different motors to cargoes. We find that recruiting myosin-V to kinesin-propelled cargoes at approximately equal numbers is sufficient to stall motility. Kinesin-driven cargoes entering the axon were arrested in the axon initial segment (AIS upon myosin-V recruitment and accumulated in distinct actin-rich hotspots. Importantly, unlike proposed previously, myosin-V did not return these cargoes to the cell body, suggesting that additional mechanism are required to establish cargo retrieval from the AIS.

  18. The class V myosin motor, myosin 5c, localizes to mature secretory vesicles and facilitates exocytosis in lacrimal acini.

    Science.gov (United States)

    Marchelletta, Ronald R; Jacobs, Damon T; Schechter, Joel E; Cheney, Richard E; Hamm-Alvarez, Sarah F

    2008-07-01

    We investigated the role of the actin-based myosin motor, myosin 5c (Myo5c) in vesicle transport in exocrine secretion. Lacrimal gland acinar cells (LGAC) are the major source for the regulated secretion of proteins from the lacrimal gland into the tear film. Confocal fluorescence and immunogold electron microscopy revealed that Myo5c was associated with secretory vesicles in primary rabbit LGAC. Upon stimulation of secretion with the muscarinic agonist, carbachol, Myo5c was also detected in association with actin-coated fusion intermediates. Adenovirus-mediated expression of green fluorescent protein (GFP) fused to the tail domain of Myo5c (Ad-GFP-Myo5c-tail) showed that this protein was localized to secretory vesicles. Furthermore, its expression induced a significant (P < or = 0.05) decrease in carbachol-stimulated release of two secretory vesicle content markers, secretory component and syncollin-GFP. Adenovirus-mediated expression of GFP appended to the full-length Myo5c (Ad-GFP-Myo5c-full) was used in parallel with adenovirus-mediated expression of GFP-Myo5c-tail in LGAC to compare various parameters of secretory vesicles labeled with either GFP-labeled protein in resting and stimulated LGAC. These studies revealed that the carbachol-stimulated increase in secretory vesicle diameter associated with compound fusion of secretory vesicles that was also exhibited by vesicles labeled with GFP-Myo5c-full was impaired in vesicles labeled with GFP-Myo5c-tail. A significant decrease in GFP labeling of actin-coated fusion intermediates was also seen in carbachol-stimulated LGAC transduced with GFP-Myo5c-tail relative to LGAC transduced with GFP-Myo5c-full. These results suggest that Myo5c participates in apical exocytosis of secretory vesicles.

  19. Interaction of Myosin Phosphatase Target Subunit (MYPT1) with Myosin Phosphatase-RhoA Interacting Protein (MRIP): A Role of Glutamic Acids in the Interaction.

    Science.gov (United States)

    Lee, Eunhee; Stafford, Walter F

    2015-01-01

    Scaffold proteins bind to and functionally link protein members of signaling pathways. Interaction of the scaffold proteins, myosin phosphatase target subunit (MYPT1) and myosin phosphatase-RhoA interacting protein (MRIP), causes co-localization of myosin phosphatase and RhoA to actomyosin. To examine biophysical properties of interaction of MYPT1 with MRIP, we employed analytical ultracentrifugation and surface plasmon resonance. In regard to MRIP, its residues 724-837 are sufficient for the MYPT1/MRIP interaction. Moreover, MRIP binds to MYPT1 as either a monomer or a dimer. With respect to MYPT1, its leucine repeat region, LR (residues 991-1030) is sufficient to account for the MYPT1/MRIP interaction. Furthermore, point mutations that replace glutamic acids 998-1000 within LR reduced the binding affinity toward MRIP. This suggests that the glutamic acids of MYPT1 play an important role in the interaction.

  20. Recent advances in bound state quantum electrodynamics

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Lepage, G.P.

    1977-06-01

    Recent developments are reviewed in four areas of computational quantum electrodynamics: a new relativistic two-body formalism equal in rigor to the Bethe-Salpeter formalism but with strong calculational advantages is discussed; recent work on the computation of the decay rate of bound systems (positronium in particular) is presented; limits on possible composite structure of leptons are discussed; a new multidimensional integration program ('VEGAS') suitable for higher order calculations is presented

  1. Human myosin VIIa is a very slow processive motor protein on various cellular actin structures.

    Science.gov (United States)

    Sato, Osamu; Komatsu, Satoshi; Sakai, Tsuyoshi; Tsukasaki, Yoshikazu; Tanaka, Ryosuke; Mizutani, Takeomi; Watanabe, Tomonobu M; Ikebe, Reiko; Ikebe, Mitsuo

    2017-06-30

    Human myosin VIIa (MYO7A) is an actin-linked motor protein associated with human Usher syndrome (USH) type 1B, which causes human congenital hearing and visual loss. Although it has been thought that the role of human myosin VIIa is critical for USH1 protein tethering with actin and transportation along actin bundles in inner-ear hair cells, myosin VIIa's motor function remains unclear. Here, we studied the motor function of the tail-truncated human myosin VIIa dimer (HM7AΔTail/LZ) at the single-molecule level. We found that the HM7AΔTail/LZ moves processively on single actin filaments with a step size of 35 nm. Dwell-time distribution analysis indicated an average waiting time of 3.4 s, yielding ∼0.3 s -1 for the mechanical turnover rate; hence, the velocity of HM7AΔTail/LZ was extremely slow, at 11 nm·s -1 We also examined HM7AΔTail/LZ movement on various actin structures in demembranated cells. HM7AΔTail/LZ showed unidirectional movement on actin structures at cell edges, such as lamellipodia and filopodia. However, HM7AΔTail/LZ frequently missed steps on actin tracks and exhibited bidirectional movement at stress fibers, which was not observed with tail-truncated myosin Va. These results suggest that the movement of the human myosin VIIa motor protein is more efficient on lamellipodial and filopodial actin tracks than on stress fibers, which are composed of actin filaments with different polarity, and that the actin structures influence the characteristics of cargo transportation by human myosin VIIa. In conclusion, myosin VIIa movement appears to be suitable for translocating USH1 proteins on stereocilia actin bundles in inner-ear hair cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. High-speed broadband monitoring of cell viscoelasticity in real time shows myosin-dependent oscillations.

    Science.gov (United States)

    Yan, Bo; Ren, Juan; Zheng, Xi; Liu, Yue; Zou, Qingze

    2017-12-01

    Study of the dynamic evolutions of cell viscoelasticity is important as during cell activities such as cell metastasis and invasion, the rheological behaviors of the cells also change dynamically, reflecting the biophysical and biochemical connections between the outer cortex and the intracellular structures. Although the time variations of the static modulus of cells have been investigated, few studies have been reported on the dynamic variations of the frequency-dependent viscoelasticity of cells. Measuring and monitoring such dynamic evolutions of cells at nanoscale can be challenging as the measurement needs to meet two objectives inherently contradictory to each other-the measurement must be broadband (to cover a large frequency spectrum) but also rapid (to capture the time-elapsed changes). In this study, we exploited a recently developed control-based nanomechanical protocol of atomic force microscope to monitor in real time the dynamic evolutions of the viscoelasticity of live human prostate cancer cells (PC-3 cells) and study its dependence on myosin activities. We found that the viscoelasticity of PC-3 cells, followed the power law, and oscillated at a period of about 200 s. Both the amplitude and the frequency of the oscillation strongly depended on the intracellular calcium and blebbistatin-sensitive motor proteins.

  3. Insight into the mechanism of fast movement of myosin from Chara corallina.

    Science.gov (United States)

    Sumiyoshi, Hiroki; Ooguchi, Masami; Ooi, Atsushi; Okagaki, Tsuyoshi; Higashi-Fujime, Sugie

    2007-02-01

    Chara myosin, two-headed plant myosin belonging to class XI, slides F-actin at maximally 60 microm s(-1). To elucidate the mechanism of this fast sliding, we extensively investigated its mechanochemical properties. The maximum actin activated ATPase activity, Vmax, was 21.3 s(-1) head(-1) in a solution, but when myosin was immobilized on the surface, its activity was 57.6 s(-1) head(-1) at 2 mg ml(-1) of F-actin. The sliding velocity and the actin activated ATPase activity were greatly inhibited by ADP, suggesting that ADP dissociation was the rate limiting step. With the extensive assay of motility by varying the surface density, the duty ratio of Chara myosin was found to be 0.49-0.44 from velocity measurements and 0.34 from the landing rate analysis. At the surface density of 10 molecules microm(-2), Chara myosin exhibited pivot movement under physiological conditions. Based on the results obtained, we will discuss the sliding mechanism of Chara myosin according to the working stroke model in terms of its physiological aspects. aspects. (c) 2006 Wiley-Liss, Inc.

  4. Function of myosin during entry and egress of equid herpesvirus type 1 in primary murine neurons.

    Science.gov (United States)

    Cymerys, J; Słońska, A; Skwarska, J; Bańbura, M W

    Equid herpesvirus type 1 (EHV-1) is a major pathogen of horses with a worldwide distribution, which can cause various clinical signs ranging from mild respiratory disease to neurological disorders. To initiate an effective infection, EHV-1 evolved a broad spectrum of mechanisms exploiting the host cell, including its actin filaments. An actin-myosin-driven transport has been described to precede cellular entry of different viruses. Therefore, in the present study we investigated the role of actin motor protein - myosin, during replication of two EHV-1 strains: Jan-E (wild-type EHV-1 strain isolated from aborted equine fetus) and Rac-H (attenuated strain highly adapted in cell cultures in vitro) in primary murine neurons. In order to investigate this, we used two inhibitors: blebbistatin (BLB; non-muscle myosin II inhibitor) and 2,3-butanedione monoxime (BDM; inhibitor of myosin ATPase). Our results demonstrated that limitation of Jan-E EHV-1 replication occurred in cells treated with myosin inhibitor, which confirmed the important role of actin motor proteins during the entry and egress of EHV-1 virions. Application of blebbistatin did not affect Rac-H EHV-1 replication, while BDM caused reduction of replication in murine neurons. Based on these results it can be assumed that EHV-1 virion movement was myosin-dependent.

  5. Smooth muscle actin and myosin expression in cultured airway smooth muscle cells.

    Science.gov (United States)

    Wong, J Z; Woodcock-Mitchell, J; Mitchell, J; Rippetoe, P; White, S; Absher, M; Baldor, L; Evans, J; McHugh, K M; Low, R B

    1998-05-01

    In this study, the expression of smooth muscle actin and myosin was examined in cultures of rat tracheal smooth muscle cells. Protein and mRNA analyses demonstrated that these cells express alpha- and gamma-smooth muscle actin and smooth muscle myosin and nonmuscle myosin-B heavy chains. The expression of the smooth muscle specific actin and myosin isoforms was regulated in the same direction when growth conditions were changed. Thus, at confluency in 1 or 10% serum-containing medium as well as for low-density cells (50-60% confluent) deprived of serum, the expression of the smooth muscle forms of actin and myosin was relatively high. Conversely, in rapidly proliferating cultures at low density in 10% serum, smooth muscle contractile protein expression was low. The expression of nonmuscle myosin-B mRNA and protein was more stable and was upregulated only to a small degree in growing cells. Our results provide new insight into the molecular basis of differentiation and contractile function in airway smooth muscle cells.

  6. High-pressure effects on the molecular aggregation and physicochemical properties of myosin in relation to heat gelation.

    Science.gov (United States)

    Xue, Siwen; Yang, Huijuan; Wang, Huhu; Tendu, Alexander Atuya; Bai, Yun; Xu, Xinglian; Ma, Hanjun; Zhou, Guanghong

    2017-09-01

    Myosin was extracted from the M. psoas muscle of rabbits, and dissolved in 0.6M KCl buffer (pH6.5). Effects of high-pressure (HP, 100 to 300MPa, 9min, 25°C) treatment on myosin solubility, molecular traits (molecular weight and morphology), flow behavior and strength of heat-induced myosin gels were studied and compared with the untreated controls. Myosin subjected to 200MPa HP treatment had lower solubility than samples treated at other pressures (Pstrength enhancement was inferred. It is postulated that significant morphological changes in myosin accounted for changes in its functional properties, by the influence of HP treatment on protein-protein and/or protein-water interactions. There is a relationship between molecular morphology and the coalescing behavior of myosin, since significant changes of both attributes were observed at pressures ≥200MPa. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Myosin Va participates in acrosomal formation and nuclear morphogenesis during spermatogenesis of Chinese mitten crab Eriocheir sinensis.

    Directory of Open Access Journals (Sweden)

    Xiao Sun

    Full Text Available BACKGROUND: The Chinese mitten crab Eriocheir sinensis belongs to the Class Crustacea, Decapoda, Brachyura. The spermatozoon of this species is of aflagellated type, it has a spherical acrosome surrounded by the cup-shaped nucleus, which are unique to brachyurans. For the past several decades, studies on the spermatogenesis of the mitten crab mainly focus on the morphology. Compared with the extensive study of molecular mechanism of spermatogenesis in mammals, relatively less information is available in crustacean species. Myosin Va, a member of Class V myosin, has been implicated in acrosome biogenesis and vesicle transport during spermatogenesis in mammals. In the present study we demonstrate the expression and cellular localization of myosin Va during spermatogenesis in E. sinensis. METHODOLOGY/PRINCIPAL FINDINGS: Western blot demonstrated that myosin Va is expressed during spermatogenesis. Immunocytochemical and ultrastructural analyses showed that myosin Va mainly localizes in the cytoplasm in spermatocytes. At the early stage of spermiogenesis, myosin Va binds to the endoplasmic reticulum vesicle (EV and proacrosomal granule (PG. Subsequently, myosin Va localizes within the proacrosomal vesicle (PV formed by PG and EV fusion and locates in the membrane complex (MC at the mid spermatid stage. At the late spermatid stage, myosin Va is associated with the shaping nucleus and mitochondria. In mature spermatozoon, myosin Va predominates in acrosomal tubule (AT and nucleus. CONCLUSIONS/SIGNIFICANCE: Our study demonstrates that myosin Va may be involved in acrosome biogenesis and nuclear morphogenesis during spermatogenesis in E. sinensis. Considering the distribution and molecular characteristics of myosin Va, we also propose a hypothesis of AT formation in this species. It is the first time to uncover the role of myosin Va in crustacean spermatogenesis.

  8. Genome-wide identification, splicing, and expression analysis of the myosin gene family in maize (Zea mays).

    Science.gov (United States)

    Wang, Guifeng; Zhong, Mingyu; Wang, Jiajia; Zhang, Jushan; Tang, Yuanping; Wang, Gang; Song, Rentao

    2014-03-01

    The actin-based myosin system is essential for the organization and dynamics of the endomembrane system and transport network in plant cells. Plants harbour two unique myosin groups, class VIII and class XI, and the latter is structurally and functionally analogous to the animal and fungal class V myosin. Little is known about myosins in grass, even though grass includes several agronomically important cereal crops. Here, we identified 14 myosin genes from the genome of maize (Zea mays). The relatively larger sizes of maize myosin genes are due to their much longer introns, which are abundant in transposable elements. Phylogenetic analysis indicated that maize myosin genes could be classified into class VIII and class XI, with three and 11 members, respectively. Apart from subgroup XI-F, the remaining subgroups were duplicated at least in one analysed lineage, and the duplication events occurred more extensively in Arabidopsis than in maize. Only two pairs of maize myosins were generated from segmental duplication. Expression analysis revealed that most maize myosin genes were expressed universally, whereas a few members (XI-1, -6, and -11) showed an anther-specific pattern, and many underwent extensive alternative splicing. We also found a short transcript at the O1 locus, which conceptually encoded a headless myosin that most likely functions at the transcriptional level rather than via a dominant-negative mechanism at the translational level. Together, these data provide significant insights into the evolutionary and functional characterization of maize myosin genes that could transfer to the identification and application of homologous myosins of other grasses.

  9. Bounding approaches to system identification

    CERN Document Server

    Norton, John; Piet-Lahanier, Hélène; Walter, Éric

    1996-01-01

    In response to the growing interest in bounding error approaches, the editors of this volume offer the first collection of papers to describe advances in techniques and applications of bounding of the parameters, or state variables, of uncertain dynamical systems. Contributors explore the application of the bounding approach as an alternative to the probabilistic analysis of such systems, relating its importance to robust control-system design.

  10. Exploration of flexible phenylpropylurea scaffold as novel cardiac myosin activators for the treatment of systolic heart failure.

    Science.gov (United States)

    Manickam, Manoj; Jalani, Hitesh B; Pillaiyar, Thanigaimalai; Sharma, Niti; Boggu, Pulla Reddy; Venkateswararao, Eeda; Lee, You-Jung; Jeon, Eun-Seok; Jung, Sang-Hun

    2017-07-07

    A series of flexible urea derivatives have been synthesized and demonstrated as selective cardiac myosin ATPase activator. Among them 1-phenethyl-3-(3-phenylpropyl)urea (1, cardiac myosin ATPase activation at 10 μM = 51.1%; FS = 18.90; EF = 12.15) and 1-benzyl-3-(3-phenylpropyl)urea (9, cardiac myosin ATPase activation = 53.3%; FS = 30.04; EF = 18.27) showed significant activity in vitro and in vivo. The change of phenyl ring with tetrahydropyran-4-yl moiety viz., 1-(3-phenylpropyl)-3-((tetrahydro-2H-pyran-4-yl)methyl)urea (14, cardiac myosin ATPase activation = 81.4%; FS = 20.50; EF = 13.10), and morpholine moiety viz., 1-(2-morpholinoethyl)-3-(3-phenylpropyl)urea (21, cardiac myosin ATPase activation = 44.0%; FS = 24.79; EF = 15.65), proved to be efficient to activate the cardiac myosin. The potent compounds 1, 9, 14 and 21 were found to be selective for cardiac myosin over skeletal and smooth myosins. Thus, these urea derivatives are potent scaffold to develop as a newer cardiac myosin activator for the treatment of systolic heart failure. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  11. Controllable molecular motors engineered from myosin and RNA

    Science.gov (United States)

    Omabegho, Tosan; Gurel, Pinar S.; Cheng, Clarence Y.; Kim, Laura Y.; Ruijgrok, Paul V.; Das, Rhiju; Alushin, Gregory M.; Bryant, Zev

    2018-01-01

    Engineering biomolecular motors can provide direct tests of structure-function relationships and customized components for controlling molecular transport in artificial systems1 or in living cells2. Previously, synthetic nucleic acid motors3-5 and modified natural protein motors6-10 have been developed in separate complementary strategies to achieve tunable and controllable motor function. Integrating protein and nucleic-acid components to form engineered nucleoprotein motors may enable additional sophisticated functionalities. However, this potential has only begun to be explored in pioneering work harnessing DNA scaffolds to dictate the spacing, number and composition of tethered protein motors11-15. Here, we describe myosin motors that incorporate RNA lever arms, forming hybrid assemblies in which conformational changes in the protein motor domain are amplified and redirected by nucleic acid structures. The RNA lever arm geometry determines the speed and direction of motor transport and can be dynamically controlled using programmed transitions in the lever arm structure7,9. We have characterized the hybrid motors using in vitro motility assays, single-molecule tracking, cryo-electron microscopy and structural probing16. Our designs include nucleoprotein motors that reversibly change direction in response to oligonucleotides that drive strand-displacement17 reactions. In multimeric assemblies, the controllable motors walk processively along actin filaments at speeds of 10-20 nm s-1. Finally, to illustrate the potential for multiplexed addressable control, we demonstrate sequence-specific responses of RNA variants to oligonucleotide signals.

  12. Myosin isoenzyme distribution in overloaded human atrial tissue.

    Science.gov (United States)

    Buttrick, P M; Malhotra, A; Brodman, R; McDermott, L; Lam, L

    1986-09-01

    Using nondenaturing polyacrylamide gel electrophoresis, we have identified two distinct myosin isoenzymes in human atrial tissue that correspond to the V1 and V3 isomyosins found in rat ventricular tissue. Normal left and right atrial appendages have approximately 50% V3. When the left atrium was exposed to hemodynamic overload secondary to mitral stenosis, the percent V3 increased to 77 +/- 10% (n = 10); exposure to hemodynamic overload secondary to mitral regurgitation caused an increase to 70 +/- 14% (n = 6). Changes in the isoenzyme pattern were seen in the right atria of patients with mitral stenosis and markedly elevated pulmonary arterial pressures compared with control subjects and patients with mitral stenosis without severe pulmonary hypertension. Several clinical variables were examined to determine which factors might influence isoenzyme expression. Age, sex, the presence of atrial fibrillation, and pulmonary capillary wedge pressure did not predict the isoenzyme pattern. However, patients with mitral valvular disease and only slightly enlarged left atria tended to have a higher percent V3 than those with massively enlarged atria. These data confirm that human atrial tissue, like rat ventricular tissue, can alter its isomyosin composition in response to a hemodynamic load. The data further suggest that the isoenzyme shift is an early adaptation to the imposed load.

  13. Strong Coupling Corrections in Quantum Thermodynamics

    Science.gov (United States)

    Perarnau-Llobet, M.; Wilming, H.; Riera, A.; Gallego, R.; Eisert, J.

    2018-03-01

    Quantum systems strongly coupled to many-body systems equilibrate to the reduced state of a global thermal state, deviating from the local thermal state of the system as it occurs in the weak-coupling limit. Taking this insight as a starting point, we study the thermodynamics of systems strongly coupled to thermal baths. First, we provide strong-coupling corrections to the second law applicable to general systems in three of its different readings: As a statement of maximal extractable work, on heat dissipation, and bound to the Carnot efficiency. These corrections become relevant for small quantum systems and vanish in first order in the interaction strength. We then move to the question of power of heat engines, obtaining a bound on the power enhancement due to strong coupling. Our results are exemplified on the paradigmatic non-Markovian quantum Brownian motion.

  14. Low upper bounds of ideals

    OpenAIRE

    Kucera, Antonin; Slaman, Theodore A.

    2007-01-01

    We show that there is a low T-upper bound for the class of K-trivial sets, namely those which are weak from the point of view of algorithmic randomness. This result is a special case of a more general characterization of ideals in Δ02 T-degrees for which there is a low T-upper bound.

  15. Bounds for Asian basket options

    Science.gov (United States)

    Deelstra, Griselda; Diallo, Ibrahima; Vanmaele, Michèle

    2008-09-01

    In this paper we propose pricing bounds for European-style discrete arithmetic Asian basket options in a Black and Scholes framework. We start from methods used for basket options and Asian options. First, we use the general approach for deriving upper and lower bounds for stop-loss premia of sums of non-independent random variables as in Kaas et al. [Upper and lower bounds for sums of random variables, Insurance Math. Econom. 27 (2000) 151-168] or Dhaene et al. [The concept of comonotonicity in actuarial science and finance: theory, Insurance Math. Econom. 31(1) (2002) 3-33]. We generalize the methods in Deelstra et al. [Pricing of arithmetic basket options by conditioning, Insurance Math. Econom. 34 (2004) 55-57] and Vanmaele et al. [Bounds for the price of discrete sampled arithmetic Asian options, J. Comput. Appl. Math. 185(1) (2006) 51-90]. Afterwards we show how to derive an analytical closed-form expression for a lower bound in the non-comonotonic case. Finally, we derive upper bounds for Asian basket options by applying techniques as in Thompson [Fast narrow bounds on the value of Asian options, Working Paper, University of Cambridge, 1999] and Lord [Partially exact and bounded approximations for arithmetic Asian options, J. Comput. Finance 10 (2) (2006) 1-52]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity.

  16. Tight bounds for break minimization

    NARCIS (Netherlands)

    Brouwer, Andries E.; Post, Gerhard F.; Woeginger, Gerhard

    We consider round-robin sports tournaments with n teams and n − 1 rounds. We construct an infinite family of opponent schedules for which every home-away assignment induces at least 1/4 n(n−2) breaks. This construction establishes a matching lower bound for a corresponding upper bound from the

  17. An upper bound on Q-star masses

    International Nuclear Information System (INIS)

    Hochron, D.R.; Selipsky, S.B.

    1992-06-01

    Q-stars (the gravitational generalization of Q-balls, strongly bound bulk matter that an appear in field theories of strongly interacting hadrons) are the only known impact objects consistent with the known bulk structure of nuclei and chiral symmetry that evade the Rhoades-Ruffini upper bound of 3.2M circle-dot . Generic bounds are quite weak: M Q-star circle-dot . If, however, we assume that the 1.558 ms pulsar is a Q-star, equilibrium. A stability criteria of rotating fluids place a much stronger upper bound of M c ≤ 5.3M circle-dot on such models under certain special assumptions. This has important implications for heavy compact objects such as Cygnus X-1

  18. Bounded Entrepreneurial Vitality

    DEFF Research Database (Denmark)

    Langevang, Thilde; Gough, Katherine V.; Yankson, Paul W.K.

    2015-01-01

    entrepreneurship and, on the other hand, female business activities characterized by vulnerability and relatively low achievement. The article shows how regulatory, normative, and cultural–cognitive institutional forces, which have been transformed over time by local and global processes and their interaction......-and-place–specific institutional contexts influence women's entrepreneurship. Drawing on primary data collected in Ghana, where exceptionally more women engage in entrepreneurial activities than men, we examine the scale and characteristics of female entrepreneurial activity, exploring the factors that account for this strong...

  19. Market Access through Bound Tariffs

    DEFF Research Database (Denmark)

    Sala, Davide; Schröder, Philipp J.H.; Yalcin, Erdal

    on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and long......WTO negotiations deal predominantly with bound - besides applied - tariff rates. But, how can reductions in tariffs ceilings, i.e. tariff rates that no exporter may ever actually be confronted with, generate market access? The answer to this question relates to the effects of tariff bindings...

  20. Metabolism of organically bound tritium

    International Nuclear Information System (INIS)

    Travis, C.C.

    1984-01-01

    The classic methodology for estimating dose to man from environmental tritium ignores the fact that organically bound tritium in foodstuffs may be directly assimilated in the bound compartment of tissues without previous oxidation. We propose a four-compartment model consisting of a free body water compartment, two organic compartments, and a small, rapidly metabolizing compartment. The utility of this model lies in the ability to input organically bound tritium in foodstuffs directly into the organic compartments of the model. We found that organically bound tritium in foodstuffs can increase cumulative total body dose by a factor of 1.7 to 4.5 times the free body water dose alone, depending on the bound-to-loose ratio of tritium in the diet. Model predictions are compared with empirical measurements of tritium in human urine and tissue samples, and appear to be in close agreement. 10 references, 4 figures, 3 tables

  1. Strain Mediated Adaptation Is Key for Myosin Mechanochemistry: Discovering General Rules for Motor Activity.

    Directory of Open Access Journals (Sweden)

    Biman Jana

    2016-08-01

    Full Text Available A structure-based model of myosin motor is built in the same spirit of our early work for kinesin-1 and Ncd towards physical understanding of its mechanochemical cycle. We find a structural adaptation of the motor head domain in post-powerstroke state that signals faster ADP release from it compared to the same from the motor head in the pre-powerstroke state. For dimeric myosin, an additional forward strain on the trailing head, originating from the postponed powerstroke state of the leading head in the waiting state of myosin, further increases the rate of ADP release. This coordination between the two heads is the essence of the processivity of the cycle. Our model provides a structural description of the powerstroke step of the cycle as an allosteric transition of the converter domain in response to the Pi release. Additionally, the variation in structural elements peripheral to catalytic motor domain is the deciding factor behind diverse directionalities of myosin motors (myosin V & VI. Finally, we observe that there are general rules for functional molecular motors across the different families. Allosteric structural adaptation of the catalytic motor head in different nucleotide states is crucial for mechanochemistry. Strain-mediated coordination between motor heads is essential for processivity and the variation of peripheral structural elements is essential for their diverse functionalities.

  2. An embryonic myosin converter domain influences Drosophila indirect flight muscle stretch activation, power generation and flight.

    Science.gov (United States)

    Wang, Qian; Newhard, Christopher S; Ramanath, Seemanti; Sheppard, Debra; Swank, Douglas M

    2014-01-15

    Stretch activation (SA) is critical to the flight ability of insects powered by asynchronous, indirect flight muscles (IFMs). An essential muscle protein component for SA and power generation is myosin. Which structural domains of myosin are significant for setting SA properties and power generation levels is poorly understood. We made use of the transgenic techniques and unique single muscle myosin heavy chain gene of Drosophila to test the influence of the myosin converter domain on IFM SA and power generation. Replacing the endogenous converter with an embryonic version decreased SA tension and the rate of SA tension generation. The alterations in SA properties and myosin kinetics from the converter exchange caused power generation to drop to 10% of control fiber power when the optimal conditions for control fibers - 1% muscle length (ML) amplitude and 150 Hz oscillation frequency - were applied to fibers expressing the embryonic converter (IFI-EC). Optimizing conditions for IFI-EC fiber power production, by doubling ML amplitude and decreasing oscillation frequency by 60%, improved power output to 60% of optimized control fiber power. IFI-EC flies altered their aerodynamic flight characteristics to better match optimal fiber power generation conditions as wing beat frequency decreased and wing stroke amplitude increased. This enabled flight in spite of the drastic changes to fiber mechanical performance.

  3. Native myosin from adult rabbit skeletal muscle: isoenzymes and states of aggregation.

    Science.gov (United States)

    Morel, J E; D'hahan, N; Taouil, K; Francin, M; Aguilar, A; Dalbiez, J P; Merah, Z; Grussaute, H; Hilbert, B; Ollagnon, F; Selva, G; Piot, F

    1998-04-21

    The globular heads of skeletal muscle myosin have been shown to exist as isoenzymes S1 (A1) and S1 (A2), and there are also isoforms of the heavy chains. Using capillary electrophoresis, we found two dominant isoenzymes of the whole native myosin molecule, in agreement with what has previously been found by various techniques for native and nondenatured myosin from adult rabbits. Findings about possible states of aggregation of myosin and its heads are contradictory. By analytical ultracentrifugation, we confirmed the existence of a tail-tail dimer. By laser light scattering, we found a head-head dimer in the presence of MgATP. Capillary electrophoresis coupled with analytical ultracentrifugation and laser light scattering led us to refine these results. We found tail-tail dimers in a conventional buffer. We found tail-tail and head-head dimers in the presence of 0.5 mM MgATP and pure head-head dimers in the presence of 6 mM MgATP. All the dimers were homodimers. Naming the dominant isoenzymes of myosin a and b, we observed tail-tail dimers with isoenzyme a (TaTa) and with isoenzyme b (TbTb) and also head-head dimers with isoenzyme a (HaHa) and with isoenzyme b (HbHb).

  4. Response of slow and fast muscle to hypothyroidism: maximal shortening velocity and myosin isoforms

    Science.gov (United States)

    Caiozzo, V. J.; Herrick, R. E.; Baldwin, K. M.

    1992-01-01

    This study examined both the shortening velocity and myosin isoform distribution of slow- (soleus) and fast-twitch (plantaris) skeletal muscles under hypothyroid conditions. Adult female Sprague-Dawley rats were randomly assigned to one of two groups: control (n = 7) or hypothyroid (n = 7). In both muscles, the relative contents of native slow myosin (SM) and type I myosin heavy chain (MHC) increased in response to the hypothyroid treatment. The effects were such that the hypothyroid soleus muscle expressed only the native SM and type I MHC isoforms while repressing native intermediate myosin and type IIA MHC. In the plantaris, the relative content of native SM and type I MHC isoforms increased from 5 to 13% and from 4 to 10% of the total myosin pool, respectively. Maximal shortening velocity of the soleus and plantaris as measured by the slack test decreased by 32 and 19%, respectively, in response to hypothyroidism. In contrast, maximal shortening velocity as estimated by force-velocity data decreased only in the soleus (-19%). No significant change was observed for the plantaris.

  5. Myosin VI deafness mutation prevents the initiation of processive runs on actin.

    Science.gov (United States)

    Pylypenko, Olena; Song, Lin; Shima, Ai; Yang, Zhaohui; Houdusse, Anne M; Sweeney, H Lee

    2015-03-17

    Mutations in the reverse-direction myosin, myosin VI, are associated with deafness in humans and mice. A myosin VI deafness mutation, D179Y, which is in the transducer of the motor, uncoupled the release of the ATP hydrolysis product, inorganic phosphate (Pi), from dependency on actin binding and destroyed the ability of single dimeric molecules to move processively on actin filaments. We observed that processive movement is rescued if ATP is added to the mutant dimer following binding of both heads to actin in the absence of ATP, demonstrating that the mutation selectively destroys the initiation of processive runs at physiological ATP levels. A drug (omecamtiv) that accelerates the actin-activated activity of cardiac myosin was able to rescue processivity of the D179Y mutant dimers at physiological ATP concentrations by slowing the actin-independent release of Pi. Thus, it may be possible to create myosin VI-specific drugs that rescue the function of deafness-causing mutations.

  6. [Myosin B ATPase activity of the intestinal smooth muscle in intestinal obstruction].

    Science.gov (United States)

    Takamatsu, H

    1983-06-01

    Intestinal smooth myosin B was prepared from muscle layers around the lesion in dogs with experimental colonic stenosis and in patients with congenital intestinal obstruction. Mg2+-ATPase activity of the myosin B was compared between the proximal dilated segment and distal segment to obstruction. Experimental colonic stenosis: In early period after surgery, proximal colons showed higher activity of myosin B ATPase than distal colons, decreasing to less than distal colon as time passed. Congenital intestinal obstruction: In three cases, whose atresia might have occurred at earlier period of gestation, proximal bowels showed less activity of myosin B ATPase than distal bowels. However, in two cases, whose atresia might have occurred at later period of gestation, and two cases with intestinal stenosis, proximal bowels indicated higher activity of myosin B ATPase than distal bowels. These data suggested that the contractibility of the proximal intestine was depending on the duration of obstruction, and it was depressed in the former patients and was accelerated in the latter patients. These results suggested that the extensive resection of dilated proximal bowel in the congenital atresia is not always necessary to obtain good postoperative intestinal dynamics at the operation of the atresial lesions which may be induced at later period of gestation. They also suggested that surgery for intestinal obstruction should be performed before the depression of intestinal contractibility to get good bowel function.

  7. Infinite Horizon Discrete Time Control Problems for Bounded Processes

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available We establish Pontryagin Maximum Principles in the strong form for infinite horizon optimal control problems for bounded processes, for systems governed by difference equations. Results due to Ioffe and Tihomirov are among the tools used to prove our theorems. We write necessary conditions with weakened hypotheses of concavity and without invertibility, and we provide new results on the adjoint variable. We show links between bounded problems and nonbounded ones. We also give sufficient conditions of optimality.

  8. Caldesmon inhibits the actin-myosin interaction by changing its spatial orientation and mobility during the ATPase activity cycle.

    Science.gov (United States)

    Kulikova, Natalia; Pronina, Olga E; Dabrowska, Renata; Borovikov, Yurii S

    2007-06-01

    Orientation and mobility of acrylodan fluorescent probe specifically bound to caldesmon Cys580 incorporated into muscle ghost fibers decorated with myosin S1 and containing tropomyosin was studied in the presence or absence of MgADP, MgAMP-PNP, MgATPgammaS or MgATP. Modeling of various intermediate states of actomyosin has shown discrete changes in orientation and mobility of the dye dipoles which is the evidence for multistep changes in the structural changes of caldesmon during the ATPase hydrolysis cycle. It is suggested that S1 interaction with actin results in nucleotide-dependent displacement of the C-terminal part of caldesmon molecule and changes in its mobility. Thus inhibition of the actomyosin ATPase activity may be due to changes in caldesmon position on the thin filament and its interaction with actin. Our new findings described in the present paper as well as those published recently elsewhere might conciliate the two existing models of molecular mechanism of inhibition of the actomyosin ATPase by caldesmon.

  9. Bounds on charge and heat diffusivities in momentum dissipating holography

    Energy Technology Data Exchange (ETDEWEB)

    Amoretti, Andrea [Dipartimento di Fisica, Università di Genova,via Dodecaneso 33, I-16146, Genova (Italy); INFN - Sezione di Genova,via Dodecaneso 33, I-16146, Genova (Italy); Lorentz Institute for Theoretical Physics,Niels Bohrweg 2, Leiden NL-2333 CA (Netherlands); Braggio, Alessandro [INFN - Sezione di Genova,via Dodecaneso 33, I-16146, Genova (Italy); CNR-SPIN,Via Dodecaneso 33, 16146, Genova (Italy); Magnoli, Nicodemo [Dipartimento di Fisica, Università di Genova,via Dodecaneso 33, I-16146, Genova (Italy); INFN - Sezione di Genova,via Dodecaneso 33, I-16146, Genova (Italy); Musso, Daniele [Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, I-34151 Trieste (Italy)

    2015-07-20

    Inspired by a recently conjectured universal bound for thermo-electric diffusion constants in quantum critical, strongly coupled systems and relying on holographic analytical computations, we investigate the possibility of formulating Planckian bounds in different holographic models featuring momentum dissipation. For a certain family of solutions to a simple massive gravity dilaton model at zero charge density we find linear in temperature resistivity and entropy density alongside a constant electric susceptibility. In addition we explicitly find that the sum of the thermo-electric diffusion constants is bounded.

  10. A bioinformatic and computational study of myosin phosphatase subunit diversity.

    Science.gov (United States)

    Dippold, Rachael P; Fisher, Steven A

    2014-08-01

    Variability in myosin phosphatase (MP) subunits may provide specificity in signaling pathways that regulate muscle tone. We utilized public databases and computational algorithms to investigate the phylogenetic diversity of MP regulatory (PPP1R12A-C) and inhibitory (PPP1R14A-D) subunits. The comparison of exonic coding sequences and expression data confirmed or refuted the existence of isoforms and their tissue-specific expression in different model organisms. The comparison of intronic and exonic sequences identified potential expressional regulatory elements. As examples, smooth muscle MP regulatory subunit (PPP1R12A) is highly conserved through evolution. Its alternative exon E24 is present in fish through mammals with two invariant features: 1) a reading frame shift generating a premature termination codon and 2) a hexanucleotide sequence adjacent to the 3' splice site hypothesized to be a novel suppressor of exon splicing. A characteristic of the striated muscle MP regulatory subunit (PPP1R12B) locus is numerous and phylogenetically variable transcriptional start sites. In fish this locus only codes for the small (M21) subunit, suggesting the primordial function of this gene. Inhibitory subunits show little intragenic variability; their diversity is thought to have arisen by expansion and tissue-specific expression of different gene family members. We demonstrate differences in the regulatory landscape between smooth muscle enriched (PPP1R14A) and more ubiquitously expressed (PPP1R14B) family members and identify deeply conserved intronic sequence and predicted transcriptional cis-regulatory elements. This bioinformatic and computational study has uncovered a number of attributes of MP subunits that supports selection of ideal model organisms and testing of hypotheses regarding their physiological significance and regulated expression. Copyright © 2014 the American Physiological Society.

  11. Multidimensional structure-function relationships in human β-cardiac myosin from population-scale genetic variation

    NARCIS (Netherlands)

    Homburger, J.R. (Julian R.); Green, E.M. (Eric M.); Caleshu, C. (Colleen); Sunitha, M.S. (Margaret S.); Taylor, R.E. (Rebecca E.); Ruppel, K.M. (Kathleen M.); Metpally, R.P.R. (Raghu Prasad Rao); S.D. Colan (Steven); M. Michels (Michelle); Day, S.M. (Sharlene M.); I. Olivotto (Iacopo); Bustamante, C.D. (Carlos D.); Dewey, F.E. (Frederick E.); Ho, C.Y. (Carolyn Y.); Spudich, J.A. (James A.); Ashley, E.A. (Euan A.)

    2016-01-01

    textabstractMyosin motors are the fundamental force-generating elements of muscle contraction. Variation in the human β-cardiac myosin heavy chain gene (MYH7) can lead to hypertrophic cardiomyopathy (HCM), a heritable disease characterized by cardiac hypertrophy, heart failure, and sudden cardiac

  12. The local expression of adult chicken heart myosins during development. I. The three days embryonic chicken heart

    NARCIS (Netherlands)

    Sanders, E.; Moorman, A. F.; Los, J. A.

    1984-01-01

    Immunofluorescence studies were performed on serial sections of three days embryonic chicken hearts using antibodies specific for adult atrial and ventricular myosin heavy chains respectively. The anti-ventricular myosin serum reacted with the entire myocardium showing a decreasing intensity going

  13. Combining Alphas via Bounded Regression

    Directory of Open Access Journals (Sweden)

    Zura Kakushadze

    2015-11-01

    Full Text Available We give an explicit algorithm and source code for combining alpha streams via bounded regression. In practical applications, typically, there is insufficient history to compute a sample covariance matrix (SCM for a large number of alphas. To compute alpha allocation weights, one then resorts to (weighted regression over SCM principal components. Regression often produces alpha weights with insufficient diversification and/or skewed distribution against, e.g., turnover. This can be rectified by imposing bounds on alpha weights within the regression procedure. Bounded regression can also be applied to stock and other asset portfolio construction. We discuss illustrative examples.

  14. Spontaneous detachment of the leading head contributes to myosin VI backward steps.

    Directory of Open Access Journals (Sweden)

    Keigo Ikezaki

    Full Text Available Myosin VI is an ATP driven molecular motor that normally takes forward and processive steps on actin filaments, but also on occasion stochastic backward steps. While a number of models have attempted to explain the backwards steps, none offer an acceptable mechanism for their existence. We therefore performed single molecule imaging of myosin VI and calculated the stepping rates of forward and backward steps at the single molecule level. The forward stepping rate was proportional to the ATP concentration, whereas the backward stepping rate was independent. Using these data, we proposed that spontaneous detachment of the leading head is uncoupled from ATP binding and is responsible for the backward steps of myosin VI.

  15. Myosin-Powered Membrane Compartment Drives Cytoplasmic Streaming, Cell Expansion and Plant Development.

    Science.gov (United States)

    Peremyslov, Valera V; Cole, Rex A; Fowler, John E; Dolja, Valerian V

    2015-01-01

    Using genetic approaches, particle image velocimetry and an inert tracer of cytoplasmic streaming, we have made a mechanistic connection between the motor proteins (myosins XI), cargo transported by these motors (distinct endomembrane compartment defined by membrane-anchored MyoB receptors) and the process of cytoplasmic streaming in plant cells. It is shown that the MyoB compartment in Nicotiana benthamiana is highly dynamic moving with the mean velocity of ~3 μm/sec. In contrast, Golgi, mitochondria, peroxisomes, carrier vesicles and a cytosol flow tracer share distinct velocity profile with mean velocities of 0.6-1.5 μm/sec. Dominant negative inhibition of the myosins XI or MyoB receptors using overexpression of the N. benthamiana myosin cargo-binding domain or MyoB myosin-binding domain, respectively, resulted in velocity reduction for not only the MyoB compartment, but also each of the tested organelles, vesicles and cytoplasmic streaming. Furthermore, the extents of this reduction were similar for each of these compartments suggesting that MyoB compartment plays primary role in cytosol dynamics. Using gene knockout analysis in Arabidopsis thaliana, it is demonstrated that inactivation of MyoB1-4 results in reduced velocity of mitochondria implying slower cytoplasmic streaming. It is also shown that myosins XI and MyoB receptors genetically interact to contribute to cell expansion, plant growth, morphogenesis and proper onset of flowering. These results support a model according to which myosin-dependent, MyoB receptor-mediated transport of a specialized membrane compartment that is conserved in all land plants drives cytoplasmic streaming that carries organelles and vesicles and facilitates cell growth and plant development.

  16. BMP-2 Overexpression Augments Vascular Smooth Muscle Cell Motility by Upregulating Myosin Va via Erk Signaling

    Directory of Open Access Journals (Sweden)

    Ming Zhang

    2014-01-01

    Full Text Available Background. The disruption of physiologic vascular smooth muscle cell (VSMC migration initiates atherosclerosis development. The biochemical mechanisms leading to dysfunctional VSMC motility remain unknown. Recently, cytokine BMP-2 has been implicated in various vascular physiologic and pathologic processes. However, whether BMP-2 has any effect upon VSMC motility, or by what manner, has never been investigated. Methods. VSMCs were adenovirally transfected to genetically overexpress BMP-2. VSMC motility was detected by modified Boyden chamber assay, confocal time-lapse video assay, and a colony wounding assay. Gene chip array and RT-PCR were employed to identify genes potentially regulated by BMP-2. Western blot and real-time PCR detected the expression of myosin Va and the phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2. Immunofluorescence analysis revealed myosin Va expression locale. Intracellular Ca2+ oscillations were recorded. Results. VSMC migration was augmented in VSMCs overexpressing BMP-2 in a dose-dependent manner. siRNA-mediated knockdown of myosin Va inhibited VSMC motility. Both myosin Va mRNA and protein expression significantly increased after BMP-2 administration and were inhibited by Erk1/2 inhibitor U0126. BMP-2 induced Ca2+ oscillations, generated largely by a “cytosolic oscillator”. Conclusion. BMP-2 significantly increased VSMCs migration and myosin Va expression, via the Erk signaling pathway and intracellular Ca2+ oscillations. We provide additional insight into the pathophysiology of atherosclerosis, and inhibition of BMP-2-induced myosin Va expression may represent a potential therapeutic strategy.

  17. Myosin-Powered Membrane Compartment Drives Cytoplasmic Streaming, Cell Expansion and Plant Development.

    Directory of Open Access Journals (Sweden)

    Valera V Peremyslov

    Full Text Available Using genetic approaches, particle image velocimetry and an inert tracer of cytoplasmic streaming, we have made a mechanistic connection between the motor proteins (myosins XI, cargo transported by these motors (distinct endomembrane compartment defined by membrane-anchored MyoB receptors and the process of cytoplasmic streaming in plant cells. It is shown that the MyoB compartment in Nicotiana benthamiana is highly dynamic moving with the mean velocity of ~3 μm/sec. In contrast, Golgi, mitochondria, peroxisomes, carrier vesicles and a cytosol flow tracer share distinct velocity profile with mean velocities of 0.6-1.5 μm/sec. Dominant negative inhibition of the myosins XI or MyoB receptors using overexpression of the N. benthamiana myosin cargo-binding domain or MyoB myosin-binding domain, respectively, resulted in velocity reduction for not only the MyoB compartment, but also each of the tested organelles, vesicles and cytoplasmic streaming. Furthermore, the extents of this reduction were similar for each of these compartments suggesting that MyoB compartment plays primary role in cytosol dynamics. Using gene knockout analysis in Arabidopsis thaliana, it is demonstrated that inactivation of MyoB1-4 results in reduced velocity of mitochondria implying slower cytoplasmic streaming. It is also shown that myosins XI and MyoB receptors genetically interact to contribute to cell expansion, plant growth, morphogenesis and proper onset of flowering. These results support a model according to which myosin-dependent, MyoB receptor-mediated transport of a specialized membrane compartment that is conserved in all land plants drives cytoplasmic streaming that carries organelles and vesicles and facilitates cell growth and plant development.

  18. Preparation of monoclonal antibodies against cardiac myosin and some radiolabelling studies

    International Nuclear Information System (INIS)

    Bapat, K.; Venkatesh, M.; Pillai, M.R.A.; Sarma, H.D.; Sainis, K.B.

    1998-01-01

    Monoclonal antibodies were raised against myosin, a specific indicator of myocardial infarction and labelled with 125 I and 99m Tc. Human cardiac myosin was isolated from normal human heart and was used for raising the monoclonal antibodies by the hybridoma technique. Antibody producing clones were identified by ELISA and cloning was done by the limiting dilution technique. Of the 13 clones obtained, 4 were deemed suitable for further studies. The antibodies were grown in ascites, purified, isotyped and their cross reactions with other forms of myosin were estimated. All the clones showed negligible cross reaction with rabbit myosin, but reacted to different extents with bovine skeletal myosin. The most avid antibody Mab-4G4 was chosen for further labelling studies. Mab-4G4 was labelled with 125 I using different oxidising agents such as iodogen, chloramine-T and lactoperoxidase. Purified radioiodinated antibody with radiochemical purity >95% could be obtained by gel filtration. Immunoreactivity was retained as tested by binding to myosin immobilised on a solid support. Mab-4G4 was also labelled with 99m Tc using stannous tartrate as the reducing agent. Radiolabelling yield was ∼60%, the purity was >95% and the immunoreactivity was retained. Both the labelled preparations were tested for bio-distribution in normal and infarcted rats. The activity accumulation in the infarcted region was ∼ 1.5 and 3.5 times as that in normal heart muscle for 125 I and 99m Tc labelled Mab-4G4 respectively. The major problem with the iodinated antibody was the in vivo deiodination resulting in very high percentage of activity in the thyroid. Although the fraction of the total activity associated with the infarcted heart is not very impressive, the fact that the activities with the infarcted and normal hearths are significantly different is heartening. With further optimisation of labelling and use of F(ab)'2 fragments, better delineation of the infarct sites is aspired. (author)

  19. Radiation-induced myosin IIA expression stimulates collagen type I matrix reorganization.

    Science.gov (United States)

    Blockhuys, Stéphanie; Van Rompaye, Bart; De Rycke, Riet; Lambein, Kathleen; Claes, Kathleen; Bracke, Marc; De Wagter, Carlos; De Wever, Olivier

    2013-07-01

    Extracellular matrix (ECM) reorganization critically contributes to breast cancer (BC) progression and radiotherapy response. We investigated the molecular background and functional consequences of collagen type I (col-I) reorganization by irradiated breast cancer cells (BCC). Radiation-induced (RI) col-I reorganization was evaluated for MCF-7/6, MCF-7/AZ, T47D and SK-BR-3 BCC. Phase-contrast microscopy and a stressed matrix contraction assay were used for visualization and quantification of col-I reorganization. Cell-matrix interactions were assessed by the inhibition of β1 integrin (neutralizing antibody 'P5D2') or focal adhesion kinase (FAK; GSK22560098 small molecule kinase inhibitor). The role of the actomyosin cytoskeleton was explored by western blotting analysis of myosin II expression and activity; and by gene silencing of myosin IIA and pharmacological inhibition of the actomyosin system (blebbistatin, cytochalasin D). BCC death was evaluated by propidium iodide staining. We observed a radiation dose-dependent increase of col-I reorganization by BCC. β1 Integrin/FAK-mediated cell-matrix interactions are essential for RI col-I reorganization. Irradiated BCC are characterized by increased myosin IIA expression and myosin IIA-dependent col-I reorganization. Moreover, RI col-I reorganization by BCC is associated with decreased BCC death, as suggested by pharmacological targeting of the β1 integrin/FAK/myosin IIA pathway. Our data indicate the role of myosin IIA in col-I reorganization by irradiated BCC and reciprocal BCC death. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. A strongly coupled quark-gluon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Shuryak, Edward [Department of Physics and Astronomy, University at Stony Brook, NY 11794 (United States)

    2004-08-01

    Successful description of robust collective flow phenomena at RHIC by ideal hydrodynamics, recent observations of bound c-barc,q-barq states on the lattice, and other theoretical developments indicate that QGP produced at RHIC, and probably in a wider temperature region T{sub c} < T < 4T{sub c}, is not a weakly coupled quasiparticle gas as believed previously. We discuss how strong the interaction is and why it seems to generate hundreds of binary channels with bound states, surviving well inside the QGP phase. We in particular discuss their effect on pressure and viscosity. We conclude by reviewing the similar phenomena for other 'strongly coupled systems', such as (i) strongly coupled supersymmetric theories studied via Maldacena duality; (ii) trapped ultra-cold atoms with very large scattering length, tuned to Feschbach resonances.

  1. A theory of the strong interactions

    International Nuclear Information System (INIS)

    Gross, D.J.

    1979-01-01

    The most promising candidate for a fundamental microscopic theory of the strong interactions is a gauge theory of colored quarks-Quantum Chromodynamics (QCD). There are many excellent reasons for believing in this theory. It embodies the broken symmetries, SU(3) and chiral SU(3)xSU(3), of the strong interactions and reflects the success of (albeit crude) quark models in explaining the spectrum of the observed hadrons. The hidden quantum number of color, necessary to account for the quantum numbers of the low lying hadrons, plays a fundamental role in this theory as the SU(3) color gauge vector 'gluons' are the mediators of the strong interactions. The absence of physical quark states can be 'explained' by the hypothesis of color confinement i.e. that hadrons are permanently bound in color singlet bound states. Finally this theory is unique in being asymptotically free, thus accounting for the almost free field theory behvior of quarks observed at short distances. (Auth.)

  2. On functions of bounded semivariation

    Czech Academy of Sciences Publication Activity Database

    Monteiro, Giselle Antunes

    2015-01-01

    Roč. 40, č. 2 (2015), s. 233-276 ISSN 0147-1937 Institutional support: RVO:67985840 Keywords : semivariation * functions of bounded variation * regulated functions Subject RIV: BA - General Mathematics http://projecteuclid.org/euclid. rae /1491271216

  3. Computational Lower Bounds Using Diagonalization

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 7. Computational Lower Bounds Using Diagonalization - Languages, Turing Machines and Complexity Classes. M V Panduranga Rao. General Article Volume 14 Issue 7 July 2009 pp 682-690 ...

  4. The Rho kinases I and II regulate different aspects of myosin II activity

    DEFF Research Database (Denmark)

    Yoneda, Atsuko; Multhaupt, Hinke A B; Couchman, John R

    2005-01-01

    The homologous mammalian rho kinases (ROCK I and II) are assumed to be functionally redundant, based largely on kinase construct overexpression. As downstream effectors of Rho GTPases, their major substrates are myosin light chain and myosin phosphatase. Both kinases are implicated in microfilament...... bundle assembly and smooth muscle contractility. Here, analysis of fibroblast adhesion to fibronectin revealed that although ROCK II was more abundant, its activity was always lower than ROCK I. Specific reduction of ROCK I by siRNA resulted in loss of stress fibers and focal adhesions, despite...

  5. Mass spectrometry analyses of rat 2b myosin heavy chain isoform

    Czech Academy of Sciences Publication Activity Database

    Žurmanová, Jitka; Maláčová, Daniela; Půta, F.; Novák, Petr; Říčný, Jan; Soukup, Tomáš

    2007-01-01

    Roč. 56, č. 5 (2007), s. 659-662 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA304/05/0327; GA ČR(CZ) GA305/06/1115; GA MŠk(CZ) LC554 Grant - others:MYORES(XE) LSHG-CT-2004-511978 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z50200510 Source of funding: R - rámcový projekt EK Keywords : rat muscle myosin * myosin heavy chain 2b isoform * mass spectrometry Subject RIV: ED - Physiology Impact factor: 1.505, year: 2007

  6. The bound fraction of young star clusters

    Science.gov (United States)

    Brinkmann, Nina; Banerjee, Sambaran; Motwani, Bhawna; Kroupa, Pavel

    2017-04-01

    Context. The residual gas within newly formed star clusters is expelled through stellar feedback on timescales ≲ 1 Myr. The subsequent expansion of the cluster results in an unbinding of a fraction of stars, before the remaining cluster members can re-virialize and form a surviving cluster. Aims: We investigate the bound fraction after gas expulsion as a function of initial cluster mass in stars Mecl and gauge the influence of primordial mass segregation, stellar evolution and the tidal field at solar distance. We also assess the impact of the star-formation efficiency ɛSFE and gas expulsion velocity vg. Methods: We perform N-body simulations using Sverre Aarseth's NBODY7 code, starting with compact clusters in their embedded phase and approximate the gas expulsion by means of an exponentially depleting external gravitational field. We follow the process of re-virialization through detailed monitoring of different Lagrange radii over several Myr, examining initial half-mass radii of 0.1 pc, 0.3 pc and 0.5 pc and Mecl usually ranging from 5 × 103M⊙ to 5 × 104M⊙. Results: The strong impact of the relation between the gas expulsion timescale and the crossing time means that clusters with the same initial core density can have very different bound fractions. The adopted ɛSFE = 0.33 in the cluster volume results in a distinct sensitivity to vg over a wide mass range, while a variation of ɛSFE can make the cluster robust to the rapidly decreasing external potential. We confirm that primordial mass segregation leads to a smaller bound fraction, its influence possibly decreasing with mass. Stellar evolution has a higher impact on lower mass clusters, but heating through dynamical friction could expand the cluster to a similar extent. The examined clusters expand well within their tidal radii and would survive gas expulsion even in a strong tidal field.

  7. Myosin VI regulates gene pairing and transcriptional pause release in T cells.

    Science.gov (United States)

    Zorca, Cornelia E; Kim, Lark Kyun; Kim, Yoon Jung; Krause, Matthew R; Zenklusen, Daniel; Spilianakis, Charalampos G; Flavell, Richard A

    2015-03-31

    Naive CD4 T cells differentiate into several effector lineages, which generate a stronger and more rapid response to previously encountered immunological challenges. Although effector function is a key feature of adaptive immunity, the molecular basis of this process is poorly understood. Here, we investigated the spatiotemporal regulation of cytokine gene expression in resting and restimulated effector T helper 1 (Th1) cells. We found that the Lymphotoxin (LT)/TNF alleles, which encode TNF-α, were closely juxtaposed shortly after T-cell receptor (TCR) engagement, when transcription factors are limiting. Allelic pairing required a nuclear myosin, myosin VI, which is rapidly recruited to the LT/TNF locus upon restimulation. Furthermore, transcription was paused at the TNF locus and other related genes in resting Th1 cells and released in a myosin VI-dependent manner following activation. We propose that homologous pairing and myosin VI-mediated transcriptional pause release account for the rapid and efficient expression of genes induced by an external stimulus.

  8. Brush border myosin Ia inactivation in gastric but not endometrial tumors

    NARCIS (Netherlands)

    Mazzolini, Rocco; Rodrigues, Paulo; Bazzocco, Sarah; Dopeso, Higinio; Ferreira, Ana M.; Mateo-Lozano, Silvia; Andretta, Elena; Woerner, Stefan M.; Alazzouzi, Hafid; Landolfi, Stefania; Hernandez-Losa, Javier; Macaya, Irati; Suzuki, Hiromu; Ramon y Cajal, Santiago; Mooseker, Mark S.; Mariadason, John M.; Gebert, Johannes; Hofstra, Robert M. W.; Reventos, Jaume; Yamamoto, Hiroyuki; Schwartz, Simo; Arango, Diego

    2013-01-01

    Brush border Myosin Ia (MYO1A) has been shown to be frequently mutated in colorectal tumors with microsatellite instability (MSI) and to have tumor suppressor activity in intestinal tumors. Here, we investigated the frequency of frameshift mutations in the A8 microsatellite in exon 28 of MYO1A in

  9. Nucleotides increase the internal flexibility of filaments of dephosphorylated Acanthamoeba myosin II.

    Science.gov (United States)

    Redowicz, M J; Korn, E D; Rau, D C

    1996-05-24

    The actin-activated Mg(2+)-ATPase activity of Acanthamoeba myosin II minifilaments is dependent both on Mg2+ concentration and on the state of phosphorylation of three serine sites at the C-terminal end of the heavy chains. Previous electric birefringence experiments on minifilaments showed a large dependence of signal amplitude on the phosphorylation state and Mg2+ concentration, consistent with large changes in filament flexibility. These observations suggested that minifilament stiffness was important for function. We now report that the binding of nucleotides to dephosphorylated minifilaments at Mg2+ concentrations needed for optimal activity increases the flexibility by about 10-fold, as inferred from the birefringence signal amplitude increase. An increase in flexibility with nucleotide binding is not observed for dephosphorylated minifilaments at lower Mg2+ concentrations or for phosphorylated minifilaments at any Mg2+ concentrations examined. The relaxation times for minifilament rotations that are sensitive to the conformation myosin heads are also observed to depend on phosphorylation, Mg2+ concentration, and nucleotide binding. These latter experiments indicate that the actin-activated Mg2+ concentration, and nucleotide binding. These latter experiments indicate that the actin-activated Mg(2+)-ATPase activity of Acanthamoeba myosin II correlates with both changes in myosin head conformation and the ability of minifilaments to cycle between stiff and flexible conformations coupled to nucleotide binding and release.

  10. Expression of porcine myosin heavy chain 1 gene in Berkshire loins ...

    African Journals Online (AJOL)

    Expression of porcine myosin heavy chain 1 gene in Berkshire loins with a high pH24 value. Jin Hun Kang, Woo Young Bang, Eun Jung Kwon, Yong Hwa Lee, Da Hye Park, Eun Seok Cho, Min Ji Kim, Jong-Soon Choi, Hwa Chun Park, Beom Young Park, Chul Wook Kim ...

  11. The local expression of adult chicken heart myosins during development. II. Ventricular conducting tissue

    NARCIS (Netherlands)

    Sanders, E.; de Groot, I. J.; Geerts, W. J.; de Jong, F.; van Horssen, A. A.; Los, J. A.; Moorman, A. F.

    1986-01-01

    The development of the ventricular conducting tissue of the embryonic chicken heart has been studied using a previous finding that morphologically recognizable atrial conducting tissue coexpresses the atrial and the ventricular myosin isoforms. It is found that, by these criteria, at 9 days part of

  12. Localization and specificity of the phospholipid and actin binding sites on the tail of Acanthamoeba myosin IC

    Science.gov (United States)

    1992-01-01

    We used bacterially expressed beta-galactosidase fusion proteins to localize the phospholipid binding domain of Acanthamoeba myosin IC to the region between amino acids 701 and 888 in the NH2-terminal half of the tail. Using a novel immobilized ligand lipid binding assay, we determined that myosin I can bind to several different acidic phospholipids, and that binding requires a minimum of 5 mol% acidic phospholipid in a neutral lipid background. The presence of di- and triglycerides and sterols in the lipid bilayer do not contribute to the affinity of myosin I for membranes. We confirm that the ATP-insensitive actin binding site is contained in the COOH-terminal 30 kD of the tail as previously shown for Acanthamoeba myosin IA. We conclude that the association of the myosin IC tail with acidic phospholipid head groups supplies much of the energy for binding myosin I to biological membranes, but probably not specificity for targeting myosin I isoforms to different cellular locations. PMID:1607386

  13. Simulation bounds for system availability

    International Nuclear Information System (INIS)

    Tietjen, G.L.; Waller, R.A.

    1976-01-01

    System availability is a dominant factor in the practicality of nuclear power electrical generating plants. A proposed model for obtaining either lower bounds or interval estimates on availability uses observed data on ''n'' failure-to-repair cycles of the system to estimate the parameters in the time-to-failure and time-to-repair models. These estimates are then used in simulating failure/repair cycles of the system. The availability estimate is obtained for each of 5000 samples of ''n'' failure/repair cycles to form a distribution of estimates. Specific percentile points of those simulated distributions are selected as lower simulation bounds or simulation interval bounds for the system availability. The method is illustrated with operational data from two nuclear plants for which an exponential time-to-failure and a lognormal time-to-repair are assumed

  14. Testing strong interaction theories

    International Nuclear Information System (INIS)

    Ellis, J.

    1979-01-01

    The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)

  15. Comparative single-molecule and ensemble myosin enzymology: sulfoindocyanine ATP and ADP derivatives.

    Science.gov (United States)

    Oiwa, K; Eccleston, J F; Anson, M; Kikumoto, M; Davis, C T; Reid, G P; Ferenczi, M A; Corrie, J E; Yamada, A; Nakayama, H; Trentham, D R

    2000-06-01

    Single-molecule and macroscopic reactions of fluorescent nucleotides with myosin have been compared. The single-molecule studies serve as paradigms for enzyme-catalyzed reactions and ligand-receptor interactions analyzed as individual stochastic processes. Fluorescent nucleotides, called Cy3-EDA-ATP and Cy5-EDA-ATP, were derived by coupling the dyes Cy3.29.OH and Cy5.29.OH (compounds XI and XIV, respectively, in, Bioconjug. Chem. 4:105-111)) with 2'(3')-O-[N-(2-aminoethyl)carbamoyl]ATP (EDA-ATP). The ATP(ADP) analogs were separated into their respective 2'- and 3'-O-isomers, the interconversion rate of which was 30[OH(-)] s(-1) (0.016 h(-1) at pH 7.1) at 22 degrees C. Macroscopic studies showed that 2'(3')-O-substituted nucleotides had properties similar to those of ATP and ADP in their interactions with myosin, actomyosin, and muscle fibers, although the ATP analogs did not relax muscle as well as ATP did. Significant differences in the fluorescence intensity of Cy3-nucleotide 2'- and 3'-O-isomers in free solution and when they interacted with myosin were evident. Single-molecule studies using total internal reflection fluorescence microscopy showed that reciprocal mean lifetimes of the nucleotide analogs interacting with myosin filaments were one- to severalfold greater than predicted from macroscopic data. Kinetic and equilibrium data of nucleotide-(acto)myosin interactions derived from single-molecule microscopy now have a biochemical and physiological framework. This is important for single-molecule mechanical studies of motor proteins.

  16. Bounds for nonlocality distillation protocols

    International Nuclear Information System (INIS)

    Forster, Manuel

    2011-01-01

    Nonlocality can be quantified by the violation of a Bell inequality. Since this violation may be amplified by local operations, an alternative measure has been proposed--distillable nonlocality. The alternative measure is difficult to calculate exactly due to the double exponential growth of the parameter space. In this paper, we give a way to bound the distillable nonlocality of a resource by the solutions to a related optimization problem. Our upper bounds are exponentially easier to compute than the exact value and are shown to be meaningful in general and tight in some cases.

  17. Space-bounded communication complexity

    DEFF Research Database (Denmark)

    Brody, Joshua Eric; Chen, Shiteng; Papakonstantinou, Periklis A.

    2013-01-01

    In the past thirty years, Communication Complexity has emerged as a foundational tool to proving lower bounds in many areas of computer science. Its power comes from its generality, but this generality comes at a price---no superlinear communication lower bound is possible, since a player may...... communicate his entire input. However, what if the players are limited in their ability to recall parts of their interaction? We introduce memory models for 2-party communication complexity. Our general model is as follows: two computationally unrestricted players, Alice and Bob, each have s(n) bits of memory...

  18. Bound entanglement and local realism

    International Nuclear Information System (INIS)

    Kaszlikowski, Dagomir; Zukowski, Marek; Gnacinski, Piotr

    2002-01-01

    We show using a numerical approach, which gives necessary and sufficient conditions for the existence of local realism, that the bound entangled state presented in Bennett et al. [Phys. Rev. Lett. 82, 5385 (1999)] admits a local and realistic description. We also find the lowest possible amount of some appropriate entangled state that must be ad-mixed to the bound entangled state so that the resulting density operator has no local and realistic description and as such can be useful in quantum communication and quantum computation

  19. Market access through bound tariffs

    DEFF Research Database (Denmark)

    Sala, Davide; Yalcin, Erdal; Schröder, Philipp

    2010-01-01

    WTO negotiations deal predominantly with bound - besides applied - tariff rates. But, how can reductions in tariffs ceilings, i.e. tariff rates that no exporter may ever actually be confronted with, generate market access? The answer to this question relates to the effects of tariff bindings...... on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...

  20. Analysis of pressure variation of fluid in bounded circular reservoirs ...

    African Journals Online (AJOL)

    The result obtained at the wellbore was compared with the results obtained by Van Everdigen and Hurst. It was shown that there was a strong positive correlation between the results. Keywords: Bounded circular reservoir, constant terminal rate, dimensionless variables, diffusivity equation, and Crank-Nicholson scheme.

  1. Relativistic shifts of bound negative-muon precession frequencies

    International Nuclear Information System (INIS)

    Brewer, J.H.; Froese, A. M.; Fryer, B.A.; Ghandi, K.

    2005-01-01

    High-field negative-muon spin precession experiments have been performed using a backward-muon beam with substantial transverse spin polarization, facilitating high-precision measurements of the magnetogyric ratio of negative muons bound to nuclei in the ground states of muonic atoms. These results may provide a testing ground for quantum electrodynamics in very strong electromagnetic fields

  2. P2-16: Dual-Bound Model and the Role of Time Bound in Perceptual Decision Making

    Directory of Open Access Journals (Sweden)

    Daeseob Lim

    2012-10-01

    Full Text Available The diffusion model (DM encapsulates the dynamics of perceptual decision within a ‘diffusion field’ that is defined by a basis with sensory-evidence (SE and time vectors. At the core of the DM, it assumes that a decision is not made until an evidence particle drifts in the diffusion field and eventually hits one of the two pre-fixed bounds defined in the SE axis. This assumption dictates when and which choice is made by referring to when and which bound will be hit by the evidence particle. What if urgency pressures the decision system to make a choice even when the evidence particle has yet hit the SE bound? Previous modeling attempts at coping with time pressure, despite differences in detail, all manipulated the coordinate of SE bounds. Here, we offer a novel solution by adopting another bound on the time axis. This ‘dual-bound’ model (DBM posits that decisions can also be made when the evidence particle hits a time bound, which is determined on a trial-by-trial basis by a ‘perceived time interval’ – how long the system can stay in the ‘diffusion’ field. The classic single-bound model (SBM exhibited systematic errors in predicting both the reaction time distributions and the time-varying bias in choice. Those errors were not corrected by previously proposed variants of the SBM until the time bound was introduced. The validity of the DBM was further supported by the strong across-individual correlation between observed precision of interval timing and the predicted trial-by-trial variability of the time bound.

  3. Entropy Bounds and Field Equations

    Directory of Open Access Journals (Sweden)

    Alessandro Pesci

    2015-08-01

    Full Text Available For general metric theories of gravity, we compare the approach that describes/derives the field equations of gravity as a thermodynamic identity with the one which looks at them from entropy bounds. The comparison is made through the consideration of the matter entropy flux across (Rindler horizons, studied by making use of the notion of a limiting thermodynamic scale l* of matter, previously introduced in the context of entropy bounds. In doing this: (i a bound for the entropy of any lump of matter with a given energy-momentum tensor Tab is considered, in terms of a quantity, which is independent of the theory of gravity that we use; this quantity is the variation of the Clausius entropy of a suitable horizon when the element of matter crosses it; (ii by making use of the equations of motion of the theory, the same quantity is then expressed as the variation of Wald’s entropy of that horizon (and this leads to a generalized form of the generalized covariant entropy bound, applicable to general diffeomorphism-invariant theories of gravity; and (iii a notion of l* for horizons, as well as an expression for it, is given.

  4. Bounded Densities and Their Derivatives

    DEFF Research Database (Denmark)

    Kozine, Igor; Krymsky, V.

    2009-01-01

    This paper describes how one can compute interval-valued statistical measures given limited information about the underlying distribution. The particular focus is on a bounded derivative of a probability density function and its combination with other available statistical evidence for computing ...

  5. Semiclassical bounds in magnetic bottles

    Czech Academy of Sciences Publication Activity Database

    Barseghyan, Diana; Exner, Pavel; Kovařík, H.; Weidl, T.

    2016-01-01

    Roč. 28, č. 1 (2016), s. 1650002 ISSN 0129-055X R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : magnetic Laplacian * discrete spectrum * eigenvalue bounds Subject RIV: BE - Theoretical Physics Impact factor: 1.426, year: 2016

  6. Positivity bounds for Sivers functions

    International Nuclear Information System (INIS)

    Kang Zhongbo; Soffer, Jacques

    2011-01-01

    We generalize a positivity constraint derived initially for parity-conserving processes to the parity-violating ones, and use it to derive non-trivial bounds on several Sivers functions, entering in the theoretical description of single spin asymmetry for various processes.

  7. Moderate deviations for bounded subsequences

    Directory of Open Access Journals (Sweden)

    George Stoica

    2006-01-01

    Full Text Available We study Davis' series of moderate deviations probabilities for Lp-bounded sequences of random variables (p>2. A certain subseries therein is convergent for the same range of parameters as in the case of martingale difference or i.i.d. sequences.

  8. Pieter Paul Rubens, "Prometheus Bound."

    Science.gov (United States)

    Shoemaker, Marla K.

    1986-01-01

    Provides a full-color reproduction of Pieter Paul Rubens' painting, "Prometheus Bound," and a lesson plan for using it with students in grades 10 through 12. The goal of the lesson is to introduce students to the techniques of design and execution used by Rubens. (JDH)

  9. Upward Bound: In the Beginning.

    Science.gov (United States)

    Groutt, John; Hill, Calvin

    2001-01-01

    Describes the early history of the Upward Bound program, including the role of President Johnson's vision, the Task Force on Poverty, the Office of Economic Opportunity, and Community Action Programs; influences on the development of the program; establishment of the program's administrative structure; pilot programs; and early problems leading to…

  10. A Functional Calculus for Quotient Bounded Operators

    Directory of Open Access Journals (Sweden)

    Sorin Mirel Stoian

    2006-12-01

    Full Text Available If (X, P is a sequentially locally convex space, then a quotient bounded operator T beloging to QP is regular (in the sense of Waelbroeck if and only if it is a bounded element (in the sense of Allan of algebra QP. The classic functional calculus for bounded operators on Banach space is generalized for bounded elements of algebra QP.

  11. Functional regions in the essential light chain of smooth muscle myosin as revealed by the mutagenesis approach.

    Science.gov (United States)

    Quevillon-Chéruel, S; Janmot, C; Nozais, M; Lompré, A M; Béchet, J J

    2000-10-01

    The endogenous essential light chain (LC17) of myosin from intestine smooth muscle was replaced with mutated essential light chains prepared using recombinant techniques. Complete exchange was observed with histidine-tagged derivatives of LC17a, LC17b and E122A-LC17a (LC17a and LC17b are the usual constituants of smooth muscle myosin), with small changes in the ATPase activity of reconstituted myosins. Much less exchange was observed with the light-chain derivative lacking the last 12 amino acid residues, demonstrating the importance of this segment, which may act as one arm of a pair of pincers to bind the myosin heavy chain.

  12. Engineering Circular Gliding of Actin Filaments Along Myosin-Patterned DNA Nanotube Rings To Study Long-Term Actin-Myosin Behaviors.

    Science.gov (United States)

    Hariadi, Rizal F; Appukutty, Abhinav J; Sivaramakrishnan, Sivaraj

    2016-09-27

    Nature has evolved molecular motors that are critical in cellular processes occurring over broad time scales, ranging from seconds to years. Despite the importance of the long-term behavior of molecular machines, topics such as enzymatic lifetime are underexplored due to the lack of a suitable approach for monitoring motor activity over long time periods. Here, we developed an "O"-shaped Myosin Empowered Gliding Assay (OMEGA) that utilizes engineered micron-scale DNA nanotube rings with precise arrangements of myosin VI to trap gliding actin filaments. This circular gliding assay platform allows the same individual actin filament to glide over the same myosin ensemble (50-1000 motors per ring) multiple times. First, we systematically characterized the formation of DNA nanotubes rings with 4, 6, 8, and 10 helix circumferences. Individual actin filaments glide along the nanotube rings with high processivity for up to 12.8 revolutions or 11 min in run time. We then show actin gliding speed is robust to variation in motor number and independent of ring curvature within our sample space (ring diameter of 0.5-4 μm). As a model application of OMEGA, we then analyze motor-based mechanical influence on "stop-and-go" gliding behavior of actin filaments, revealing that the stop-to-go transition probability is dependent on motor flexibility. Our circular gliding assay may provide a closed-loop platform for monitoring long-term behavior of broad classes of molecular motors and enable characterization of motor robustness and long time scale nanomechanical processes.

  13. Generalized bounds for convex multistage stochastic programs

    CERN Document Server

    Künzi, H; Fandel, G; Trockel, W; Basile, A; Drexl, A; Dawid, H; Inderfurth, K; Kürsten, W; Schittko, U

    2005-01-01

    This work was completed during my tenure as a scientific assistant and d- toral student at the Institute for Operations Research at the University of St. Gallen. During that time, I was involved in several industry projects in the field of power management, on the occasion of which I was repeatedly c- fronted with complex decision problems under uncertainty. Although usually hard to solve, I quickly learned to appreciate the benefit of stochastic progr- ming models and developed a strong interest in their theoretical properties. Motivated both by practical questions and theoretical concerns, I became p- ticularly interested in the art of finding tight bounds on the optimal value of a given model. The present work attempts to make a contribution to this important branch of stochastic optimization theory. In particular, it aims at extending some classical bounding methods to broader problem classes of practical relevance. This book was accepted as a doctoral thesis by the University of St. Gallen in June 2004.1...

  14. Myosins 1 and 6, myosin light chain kinase, actin and microtubules cooperate during antibody-mediated internalisation and trafficking of membrane-expressed viral antigens in feline infectious peritonitis virus infected monocytes.

    Science.gov (United States)

    Dewerchin, Hannah L; Desmarets, Lowiese M; Noppe, Ytse; Nauwynck, Hans J

    2014-02-12

    Monocytes infected with feline infectious peritonitis virus, a coronavirus, express viral proteins in their plasma membranes. Upon binding of antibodies, these proteins are quickly internalised through a new clathrin- and caveolae-independent internalisation pathway. By doing so, the infected monocytes can escape antibody-dependent cell lysis. In the present study, we investigated which kinases and cytoskeletal proteins are of importance during internalisation and subsequent intracellular transport. The experiments showed that myosin light chain kinase (MLCK) and myosin 1 are crucial for the initiation of the internalisation. With co-localisation stainings, it was found that MLCK and myosin 1 co-localise with antigens even before internalisation started. Myosin 6 co-localised with the internalising complexes during passage through the cortical actin, were it might play a role in moving or disintegrating actin filaments, to overcome the actin barrier. One minute after internalisation started, vesicles had passed the cortical actin, co-localised with microtubules and association with myosin 6 was lost. The vesicles were further transported over the microtubules and accumulated at the microtubule organising centre after 10 to 30 min. Intracellular trafficking over microtubules was mediated by MLCK, myosin 1 and a small actin tail. Since inhibiting MLCK with ML-7 was so efficient in blocking the internalisation pathway, this target can be used for the development of a new treatment for FIPV.

  15. Cardiac myosin binding protein C phosphorylation affects cross-bridge cycle's elementary steps in a site-specific manner.

    Directory of Open Access Journals (Sweden)

    Li Wang

    Full Text Available Based on our recent finding that cardiac myosin binding protein C (cMyBP-C phosphorylation affects muscle contractility in a site-specific manner, we further studied the force per cross-bridge and the kinetic constants of the elementary steps in the six-state cross-bridge model in cMyBP-C mutated transgenic mice for better understanding of the influence of cMyBP-C phosphorylation on contractile functions. Papillary muscle fibres were dissected from cMyBP-C mutated mice of ADA (Ala273-Asp282-Ala302, DAD (Asp273-Ala282-Asp302, SAS (Ser273-Ala282-Ser302, and t/t (cMyBP-C null genotypes, and the results were compared to transgenic mice expressing wide-type (WT cMyBP-C. Sinusoidal analyses were performed with serial concentrations of ATP, phosphate (Pi, and ADP. Both t/t and DAD mutants significantly reduced active tension, force per cross-bridge, apparent rate constant (2πc, and the rate constant of cross-bridge detachment. In contrast to the weakened ATP binding and enhanced Pi and ADP release steps in t/t mice, DAD mice showed a decreased ADP release without affecting the ATP binding and the Pi release. ADA showed decreased ADP release, and slightly increased ATP binding and cross-bridge detachment steps, whereas SAS diminished the ATP binding step and accelerated the ADP release step. t/t has the broadest effects with changes in most elementary steps of the cross-bridge cycle, DAD mimics t/t to a large extent, and ADA and SAS predominantly affect the nucleotide binding steps. We conclude that the reduced tension production in DAD and t/t is the result of reduced force per cross-bridge, instead of the less number of strongly attached cross-bridges. We further conclude that cMyBP-C is an allosteric activator of myosin to increase cross-bridge force, and its phosphorylation status modulates the force, which is regulated by variety of protein kinases.

  16. Surface-bound states in nanodiamonds

    Science.gov (United States)

    Han, Peng; Antonov, Denis; Wrachtrup, Jörg; Bester, Gabriel

    2017-05-01

    We show via ab initio calculations and an electrostatic model that the notoriously low, but positive, electron affinity of bulk diamond becomes negative for hydrogen passivated nanodiamonds and argue that this peculiar situation (type-II offset with a vacuum level at nearly midgap) and the three further conditions: (i) a surface dipole with positive charge on the outside layer, (ii) a spherical symmetry, and (iii) a dielectric mismatch at the surface, results in the emergence of a peculiar type of surface state localized just outside the nanodiamond. These states are referred to as "surface-bound states" and have consequently a strong environmental sensitivity. These type of states should exist in any nanostructure with negative electron affinity. We further quantify the band offsets of different type of nanostructures as well as the exciton binding energy and contrast the results with results for "conventional" silicon quantum dots.

  17. bHLH transcription factor MyoD affects myosin heavy chain expression pattern in a muscle-specific fashion.

    Science.gov (United States)

    Seward, D J; Haney, J C; Rudnicki, M A; Swoap, S J

    2001-02-01

    A strong correlative pattern between MyoD gene expression and myosin heavy chain IIB (MHC IIB) gene expression exists. To test whether this correlative relationship is causative, MHC gene expression in muscles from MyoD(-/-) mice was analyzed. The MHC IIB gene was not detectable in the MyoD(-/-) diaphragm, whereas the MHC IIB protein made up 10.0 +/- 1.7% of the MHC protein pool in the wild-type (WT) mouse diaphragm. Furthermore, the MHC IIA protein was not detectable in the MyoD(-/-) biceps brachii, and the MHC IIB protein was overexpressed in the masseter. To examine whether MyoD is required for the upregulation of the MHC IIB gene within slow muscle after disuse, MyoD(-/-) and WT hindlimb musculature was unweighted. MyoD(-/-) exhibited a diminished response in the upregulation of the MHC IIB mRNA within the soleus muscle as a result of the hindlimb unweighting. Collectively, these data suggest that MyoD plays a role in the MHC profile in a muscle-specific fashion.

  18. Thermodynamic Bounds on Precision in Ballistic Multiterminal Transport

    Science.gov (United States)

    Brandner, Kay; Hanazato, Taro; Saito, Keiji

    2018-03-01

    For classical ballistic transport in a multiterminal geometry, we derive a universal trade-off relation between total dissipation and the precision, at which particles are extracted from individual reservoirs. Remarkably, this bound becomes significantly weaker in the presence of a magnetic field breaking time-reversal symmetry. By working out an explicit model for chiral transport enforced by a strong magnetic field, we show that our bounds are tight. Beyond the classical regime, we find that, in quantum systems far from equilibrium, the correlated exchange of particles makes it possible to exponentially reduce the thermodynamic cost of precision.

  19. Computer simulation of bounded plasmas

    International Nuclear Information System (INIS)

    Lawson, W.S.

    1987-01-01

    The problems of simulating a one-dimensional bounded plasma system using particles in a gridded space are systematically explored and solutions to them are given. Such problems include the injection of particles at the boundaries, the solution of Poisson's equation, and the inclusion of an external circuit between the confining boundaries. A recently discovered artificial cooling effect is explained as being a side-effect of quiet injection, and its potential for causing serious but subtle errors in bounded simulation is noted. The methods described in the first part of the thesis are then applied to the simulation of an extension of the Pierce diode problem, specifically a Pierce diode modified by an external circuit between the electrodes. The results of these simulations agree to high accuracy with theory when a theory exists, and also show some interesting chaotic behavior in certain parameter regimes. The chaotic behavior is described in detail

  20. Bounded Rationality in Transposition Processes

    DEFF Research Database (Denmark)

    Vollaard, Hans; Martinsen, Dorte Sindbjerg

    2014-01-01

    Studies explaining the timeliness and correctness of the transposition of EU directives into national legislation have provided rather inconclusive findings. They do not offer a clear-cut prediction concerning the transposition of the patients’ rights directive, which is one of the first that con......Studies explaining the timeliness and correctness of the transposition of EU directives into national legislation have provided rather inconclusive findings. They do not offer a clear-cut prediction concerning the transposition of the patients’ rights directive, which is one of the first...... that concerns the organisation and financing of national healthcare systems. This article applies the perspective of bounded rationality to explain (irregularities in) the timely and correct transposition of EU directives. The cognitive and organisational constraints long posited by the bounded rationality...

  1. 78 FR 18326 - Agency Information Collection Activities; Comment Request; Upward Bound and Upward Bound Math...

    Science.gov (United States)

    2013-03-26

    ...; Comment Request; Upward Bound and Upward Bound Math Science Annual Performance Report AGENCY: The Office... considered public records. Title of Collection: Upward Bound and Upward Bound Math Science Annual Performance...) and Upward Bound Math and Science (UBMS) Programs. The Department is requesting a new APR because of...

  2. The pepsin digestibility of thermal gel products made from white croaker (Pennahia argentata) muscle in associating with myosin polymerization levels.

    Science.gov (United States)

    Ueki, Nobuhiko; Wan, Jianrong; Watabe, Shugo

    2014-12-01

    Thermal gels were made from white croaker (Pennahia argentata) surimi at various polymerization levels of myosin heavy chains induced by suwari treatment at 38 °C for various time periods and subsequently heated at 85 °C for 20 min. Myosin heavy chain polymerization levels were also achieved in the presence of microbial transglutaminase (MTG) added at various concentrations in the surimi. The breaking strength and breaking strain rate were markedly increased during suwari treatment up to 60 min in accordance with the increased levels of myosin heavy chain polymerization. MTG enhanced myosin heavy chain polymerization during suwari treatment for 15 and 30 min, resulting in the increase of breaking strength. The solubilization in 8 M urea and pepsin digestibility of these gels as well as angiotensin I-converting enzyme (ACE) inhibitory activity of their pepsin digests were decreased with the increased levels of myosin heavy chain polymerization. These results suggest that myosin heavy chain polymerization affects not only rheological properties of thermal gels but also their functional properties for human health. © 2014 Institute of Food Technologists®

  3. Phosphorylated peptides occur in a non-helical portion of the tail of a catch muscle myosin

    International Nuclear Information System (INIS)

    Castellani, L.; Elliott, B.W. Jr.; Cohen, C.

    1987-01-01

    Myosin from a molluscan catch muscle (the Anterior Byssus Retractor (ABRM) of Mytilus edulis) is unusual in being phosphorylated in the rod by an endogenous heavy-chain kinase. This phosphorylation enhances myosin solubility at low ionic strength and induces molecular folding of the myosin tail. Papain and chymotryptic cleavage of this myosin, phosphorylated with [γ- 32 P]ATP, indicates that the phosphorylated residues are associated with the carboxy-terminal end of the light meromyosin. Ion-exchange and reverse-phase HPLC of radiolabeled chymotryptic peptides allow the isolation of two different peptides with high specific activity. One of these peptides is rich in lysine and arginine residues, a finding consistent with the observation that basic residues often determine the substrate specificity of protein kinases. The second peptide contains proline residues. Taken together, these results suggest that, as in the case of Acanthamoeba myosin, phosphorylation occurs in a nonhelical portion of the rod that may also control solubility. Identification of the residues that are phosphorylated and their location in the rod may reveal how the phosphorylation-dependent changes observed in the myosin in vitro are related to changes in intermolecular interactions in the thick filaments in vivo

  4. Cell-scale dynamic recycling and cortical flow of the actin–myosin cytoskeleton for rapid cell migration

    Directory of Open Access Journals (Sweden)

    Shigehiko Yumura

    2012-11-01

    Actin and myosin II play major roles in cell migration. Whereas pseudopod extension by actin polymerization has been intensively researched, less attention has been paid to how the rest of the actin cytoskeleton such as the actin cortex contributes to cell migration. In this study, cortical actin and myosin II filaments were simultaneously observed in migrating Dictyostelium cells under total internal reflection fluorescence microscopy. The cortical actin and myosin II filaments remained stationary with respect to the substratum as the cells advanced. However, fluorescence recovery after photobleaching experiments and direct observation of filaments showed that they rapidly turned over. When the cells were detached from the substratum, the actin and myosin filaments displayed a vigorous retrograde flow. Thus, when the cells migrate on the substratum, the cortical cytoskeleton firmly holds the substratum to generate the motive force instead. The present studies also demonstrate how myosin II localizes to the rear region of the migrating cells. The observed dynamic turnover of actin and myosin II filaments contributes to the recycling of their subunits across the whole cell and enables rapid reorganization of the cytoskeleton.

  5. Myosin VI as a transporter and an anchor: A model for kinetics of the motor under load

    Science.gov (United States)

    Chuan, Peiying; Spudich, James; Dunn, Alexander

    2010-03-01

    Myosin VI is an actin-based motor that is thought to function both as a transporter and an anchor in vivo. In an earlier study (Altman et al, Cell 2004), inhibition of myosin VI stepping kinetics by load applied using an optical trap was observed at saturating ATP and low ADP concentrations (ADP binding increases exponentially with load was proposed. This model predicts that myosin VI functions primarily as an anchor at loads greater than ˜0.5 pN under physiological nucleotide conditions, which is potentially inconsistent with its roles in vivo. Here we present myosin VI stepping data taken at a variety of applied loads and ADP concentrations, and show that the Altman model only holds at low ADP concentrations. At higher, physiologically relevant ADP concentrations under load we observe dwell times that are an order of magnitude smaller than predicted by the Altman model. We present a modified model in which applied load alters the equilibrium between two myosin VI states with different nucleotide affinities. This new kinetic scheme accurately describes myosin VI behavior at various nucleotide conditions under a large range of loads, and explains how the motor is able to carry out its roles in vivo, both as a force-generating transporter and as an anchor.

  6. THERMAL STABILITY OF SYNTHETIC PEPTIDES MIMICKING THE SEQUENCE OF THE REGION CONTAINING THE SKIP RESIDUES IN SQUID MYOSIN ROD

    Directory of Open Access Journals (Sweden)

    Yoshihiro Ochiai

    2017-08-01

    Full Text Available Myosin is the major protein in skeletal muscles including those of fish and shellfish. The characteristics of this protein are closely related to the biological function and the quality and physical properties of musclefood. In the myosin rod (the coiled-coil region of myosin, several amino acid residues, known as skip residues, seem to destabilize the ordered structure (heptad repeat. These residues might be responsible for reducing thermal stability. Attempts were thus made to examine the role of these residues in the rod of squid myosin, based on the thermodynamic properties of synthetic peptides which have been designed to mimic the partial sequence of myosin heavy chain from the squid Todarodes pacificus mantle muscle. Five peptides, namely, with the sequence of Trp1343 -Ala1372  having the skip residue Glu1357 at the center (Peptide WT, without the skip residue (Peptide Δ, with the replacements of the skip residue (Glu by Ile, Gln and Pro (Peptides E/I, E/Q, and E/P, respectively to modify the helix forming propensity, were synthesized. The results obtained showed that the stability of the peptides as measured by circular dichroism spectrometry was in the order of Peptide Δ > Peptide WT > Peptide E/Q > Peptide E/P > Peptide E/I. It is suggested that the presence of the skip residues dexterously tunes the stability or flexibility of the coiled-coil structure, thus possibly regulating thick filament formation and further gel formation ability of myosin.

  7. Myosin VI Must Dimerize and Deploy Its Unusual Lever Arm in Order to Perform Its Cellular Roles

    Directory of Open Access Journals (Sweden)

    Monalisa Mukherjea

    2014-09-01

    Full Text Available It is unclear whether the reverse-direction myosin (myosin VI functions as a monomer or dimer in cells and how it generates large movements on actin. We deleted a stable, single-α-helix (SAH domain that has been proposed to function as part of a lever arm to amplify movements without impact on in vitro movement or in vivo functions. A myosin VI construct that used this SAH domain as part of its lever arm was able to take large steps in vitro but did not rescue in vivo functions. It was necessary for myosin VI to internally dimerize, triggering unfolding of a three-helix bundle and calmodulin binding in order to step normally in vitro and rescue endocytosis and Golgi morphology in myosin VI-null fibroblasts. A model for myosin VI emerges in which cargo binding triggers dimerization and unfolds the three-helix bundle to create a lever arm essential for in vivo functions.

  8. Calix[4]arene C-99 inhibits myosin ATPase activity and changes the organization of contractile filaments of myometrium

    Directory of Open Access Journals (Sweden)

    R. D. Labyntseva,

    2015-12-01

    Full Text Available Calix[4]arenes are cup-like macrocyclic (polyphenolic compounds, they are regarded as promising molecular “platforms” for the design of new physiologically active compounds. We have earlier found that сalix[4]arenе C-99 inhibits the ATPase activity of actomyosin and myosin subfragment-1 of pig uterus іn vitro. The aim of this study was to investigate the interaction of calix[4]arene C-99 with myosin from rat uterine myocytes. It was found that the ATPase activity of myosin prepared from pre-incubated with 100 mM of calix[4]arene C-99 myocytes was almost 50% lower than in control. Additionally, we have revealed the effect of calix[4]arene C-99 on the subcellular distribution of actin and myosin in uterus myocytes by the method of confocal microscopy. This effect can be caused by reorganization of the structure of the contractile smooth muscle cell proteins due to their interaction with calix[4]arene. The obtained results demonstrate the ability of calix[4]arene C-99 to penetrate into the uterus muscle cells and affect not only the myosin ATPase activity, but also the structure of the actin and myosin filaments in the myometrial cells. Demonstrated ability of calix[4]arene C-99 can be used for development of new pharmacological agents for efficient normalization of myometrial contractile hyperfunction.

  9. Phosphorylated peptides occur in a non-helical portion of the tail of a catch muscle myosin

    Energy Technology Data Exchange (ETDEWEB)

    Castellani, L.; Elliott, B.W. Jr.; Cohen, C.

    1987-05-01

    Myosin from a molluscan catch muscle (the Anterior Byssus Retractor (ABRM) of Mytilus edulis) is unusual in being phosphorylated in the rod by an endogenous heavy-chain kinase. This phosphorylation enhances myosin solubility at low ionic strength and induces molecular folding of the myosin tail. Papain and chymotryptic cleavage of this myosin, phosphorylated with (..gamma..-/sup 32/P)ATP, indicates that the phosphorylated residues are associated with the carboxy-terminal end of the light meromyosin. Ion-exchange and reverse-phase HPLC of radiolabeled chymotryptic peptides allow the isolation of two different peptides with high specific activity. One of these peptides is rich in lysine and arginine residues, a finding consistent with the observation that basic residues often determine the substrate specificity of protein kinases. The second peptide contains proline residues. Taken together, these results suggest that, as in the case of Acanthamoeba myosin, phosphorylation occurs in a nonhelical portion of the rod that may also control solubility. Identification of the residues that are phosphorylated and their location in the rod may reveal how the phosphorylation-dependent changes observed in the myosin in vitro are related to changes in intermolecular interactions in the thick filaments in vivo.

  10. Myosin Light Chain Kinase: A Potential Target for Treatment of Inflammatory Diseases

    Directory of Open Access Journals (Sweden)

    Yongjian Xiong

    2017-05-01

    Full Text Available Myosin light chain kinase (MLCK induces contraction of the perijunctional apical actomyosin ring in response to phosphorylation of the myosin light chain. Abnormal expression of MLCK has been observed in respiratory diseases, pancreatitis, cardiovascular diseases, cancer, and inflammatory bowel disease. The signaling pathways involved in MLCK activation and triggering of endothelial barrier dysfunction are discussed in this review. The pharmacological effects of regulating MLCK expression by inhibitors such as ML-9, ML-7, microbial products, naturally occurring products, and microRNAs are also discussed. The influence of MLCK in inflammatory diseases starts with endothelial barrier dysfunction. The effectiveness of anti-MLCK treatment may depend on alleviation of that primary pathological mechanism. This review summarizes evidence for the potential benefits of anti-MLCK agents in the treatment of inflammatory disease and the importance of avoiding treatment-related side effects, as MLCK is widely expressed in many different tissues.

  11. A semidefinite programming based branch-and-bound framework for the quadratic assignment problem

    NARCIS (Netherlands)

    Truetsch, U.

    2014-01-01

    The practical approach to calculate an exact solution for a quadratic assignment problem (QAP) via a branch-and-bound framework depends strongly on a "smart" choice of different strategies within the framework, for example the branching strategy, heuristics for the upper bound or relaxations for the

  12. Sarcomeric Myosin Expression in the Tongue Body of Humans, Macaques and Rats

    OpenAIRE

    Rahnert, Jill A.; Sokoloff, Alan J.; Burkholder, Thomas J.

    2009-01-01

    Expression of developmental and unconventional myosin heavy chain (MHC) isoforms in some adult head and neck muscles is thought to reflect specific contractile demands of muscle fibers active during kinematically complex movements. Mammalian tongue muscles are active during oromotor behaviors that encompass a wide range of tongue movement speeds and tongue shape changes (e.g. respiration, oral transport, swallowing, rejection), but the extent to which tongue muscles express developmental and ...

  13. Covalent immobilization of myosin for in-vitro motility of actin

    Indian Academy of Sciences (India)

    The resulting volume of the flow cell was 50. µl (figure 1). 2.5 In-vitro motility assay. For in-vitro assay the flow cell was inclined at an angle of 30◦. Then 100 µl of 40. µg/ml myosin was infused from one side of the flow cell and kept for 2 h incubation on ice. After incubation 100 µl of AB/BSA [(25 mM imidazole hydrochloride,.

  14. Human Masseter Muscle Fibers From the Elderly Express Less Neonatal Myosin Than Those of Young Adults

    Czech Academy of Sciences Publication Activity Database

    Cvetko, E.; Karen, Petr; Janáček, Jiří; Kubínová, Lucie; Plasencia, A.L.; Eržen, I.

    2012-01-01

    Roč. 295, č. 8 (2012), s. 1364-1372 ISSN 1932-8486 R&D Projects: GA MŠk(CZ) LC06063; GA MŠk(CZ) MEB090910 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : aging * confocal microscopy * myosin heavy chain * immunohistochemistry * muscle fiber types Subject RIV: FH - Neurology Impact factor: 1.343, year: 2012

  15. Lead reduces tension development and the myosin ATPase activity of the rat right ventricular myocardium

    Directory of Open Access Journals (Sweden)

    D.V. Vassallo

    2008-09-01

    Full Text Available Lead (Pb2+ poisoning causes hypertension, but little is known regarding its acute effects on cardiac contractility. To evaluate these effects, force was measured in right ventricular strips that were contracting isometrically in 45 male Wistar rats (250-300 g before and after the addition of increasing concentrations of lead acetate (3, 7, 10, 30, 70, 100, and 300 µM to the bath. Changes in rate of stimulation (0.1-1.5 Hz, relative potentiation after pauses of 15, 30, and 60 s, effect of Ca2+ concentration (0.62, 1.25, and 2.5 mM, and the effect of isoproterenol (20 ng/mL were determined before and after the addition of 100 µM Pb2+. Effects on contractile proteins were evaluated after caffeine treatment using tetanic stimulation (10 Hz and measuring the activity of the myosin ATPase. Pb2+ produced concentration-dependent force reduction, significant at concentrations greater than 30 µM. The force developed in response to increasing rates of stimulation became smaller at 0.5 and 0.8 Hz. Relative potentiation increased after 100 µM Pb2+ treatment. Extracellular Ca2+ increment and isoproterenol administration increased force development but after 100 µM Pb2+ treatment the force was significantly reduced suggesting an effect of the metal on the sarcolemmal Ca2+ influx. Concentration of 100 µM Pb2+ also reduced the peak and plateau force of tetanic contractions and reduced the activity of the myosin ATPase. Results showed that acute Pb2+ administration, although not affecting the sarcoplasmic reticulum activity, produces a concentration-dependent negative inotropic effect and reduces myosin ATPase activity. Results suggest that acute lead administration reduced myocardial contractility by reducing sarcolemmal calcium influx and the myosin ATPase activity. These results also suggest that lead exposure is hazardous and has toxicological consequences affecting cardiac muscle.

  16. Regulation of nonmuscle myosin II during 3-methylcholanthrene induced dedifferentiation of C2C12 myotubes

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Sumit K.; Saha, Shekhar; Das, Provas; Das, Mahua R.; Jana, Siddhartha S., E-mail: bcssj@iacs.res.in

    2014-08-01

    3-Methylcholanthrene (3MC) induces tumor formation at the site of injection in the hind leg of mice within 110 days. Recent reports reveal that the transformation of normal muscle cells to atypical cells is one of the causes for tumor formation, however the molecular mechanism behind this process is not well understood. Here, we show in an in vitro study that 3MC induces fragmentation of multinucleate myotubes into viable mononucleates. These mononucleates form colonies when they are seeded into soft agar, indicative of cellular transformation. Immunoblot analysis reveals that phosphorylation of myosin regulatory light chain (RLC{sub 20}) is 5.6±0.5 fold reduced in 3MC treated myotubes in comparison to vehicle treated myotubes during the fragmentation of myotubes. In contrast, levels of myogenic factors such as MyoD, Myogenin and cell cycle regulators such as Cyclin D, Cyclin E1 remain unchanged as assessed by real-time PCR array and reverse transcriptase PCR analysis, respectively. Interestingly, addition of the myosin light chain kinase inhibitor, ML-7, enhances the fragmentation, whereas phosphatase inhibitor perturbs the 3MC induced fragmentation of myotubes. These results suggest that decrease in RLC{sub 20} phosphorylation may be associated with the fragmentation step of dedifferentiation. - Highlights: • 3-Methylcholanthrene induces fragmentation of C2C12-myotubes. • Dedifferentiation can be divided into two steps – fragmentation and proliferation. • Fragmentation is associated with rearrangement of nonmuscle myosin II. • Genes associated with differentiation and proliferation are not altered during fragmentation. • Phosphorylation of myosin regulatory light chain is reduced during fragmentation.

  17. Regulation of nonmuscle myosin II during 3-methylcholanthrene induced dedifferentiation of C2C12 myotubes

    International Nuclear Information System (INIS)

    Dey, Sumit K.; Saha, Shekhar; Das, Provas; Das, Mahua R.; Jana, Siddhartha S.

    2014-01-01

    3-Methylcholanthrene (3MC) induces tumor formation at the site of injection in the hind leg of mice within 110 days. Recent reports reveal that the transformation of normal muscle cells to atypical cells is one of the causes for tumor formation, however the molecular mechanism behind this process is not well understood. Here, we show in an in vitro study that 3MC induces fragmentation of multinucleate myotubes into viable mononucleates. These mononucleates form colonies when they are seeded into soft agar, indicative of cellular transformation. Immunoblot analysis reveals that phosphorylation of myosin regulatory light chain (RLC 20 ) is 5.6±0.5 fold reduced in 3MC treated myotubes in comparison to vehicle treated myotubes during the fragmentation of myotubes. In contrast, levels of myogenic factors such as MyoD, Myogenin and cell cycle regulators such as Cyclin D, Cyclin E1 remain unchanged as assessed by real-time PCR array and reverse transcriptase PCR analysis, respectively. Interestingly, addition of the myosin light chain kinase inhibitor, ML-7, enhances the fragmentation, whereas phosphatase inhibitor perturbs the 3MC induced fragmentation of myotubes. These results suggest that decrease in RLC 20 phosphorylation may be associated with the fragmentation step of dedifferentiation. - Highlights: • 3-Methylcholanthrene induces fragmentation of C2C12-myotubes. • Dedifferentiation can be divided into two steps – fragmentation and proliferation. • Fragmentation is associated with rearrangement of nonmuscle myosin II. • Genes associated with differentiation and proliferation are not altered during fragmentation. • Phosphorylation of myosin regulatory light chain is reduced during fragmentation

  18. A Kinase Anchoring Protein 9 Is a Novel Myosin VI Binding Partner That Links Myosin VI with the PKA Pathway in Myogenic Cells

    Directory of Open Access Journals (Sweden)

    Justyna Karolczak

    2015-01-01

    Full Text Available Myosin VI (MVI is a unique motor protein moving towards the minus end of actin filaments unlike other known myosins. Its important role has recently been postulated for striated muscle and myogenic cells. Since MVI functions through interactions of C-terminal globular tail (GT domain with tissue specific partners, we performed a search for MVI partners in myoblasts and myotubes using affinity chromatography with GST-tagged MVI-GT domain as a bait. A kinase anchoring protein 9 (AKAP9, a regulator of PKA activity, was identified by means of mass spectrometry as a possible MVI interacting partner both in undifferentiated and differentiating myoblasts and in myotubes. Coimmunoprecipitation and proximity ligation assay confirmed that both proteins could interact. MVI and AKAP9 colocalized at Rab5 containing early endosomes. Similarly to MVI, the amount of AKAP9 decreased during myoblast differentiation. However, in MVI-depleted cells, both cAMP and PKA levels were increased and a change in the MVI motor-dependent AKAP9 distribution was observed. Moreover, we found that PKA phosphorylated MVI-GT domain, thus implying functional relevance of MVI-AKAP9 interaction. We postulate that this novel interaction linking MVI with the PKA pathway could be important for targeting AKAP9-PKA complex within cells and/or providing PKA to phosphorylate MVI tail domain.

  19. Smooth muscle myosin inhibition: a novel therapeutic approach for pulmonary hypertension.

    Directory of Open Access Journals (Sweden)

    David Ho

    Full Text Available Pulmonary hypertension remains a major clinical problem despite current therapies. In this study, we examine for the first time a novel pharmacological target, smooth muscle myosin, and determine if the smooth muscle myosin inhibitor, CK-2019165 (CK-165 ameliorates pulmonary hypertension.Six domestic female pigs were surgically instrumented to measure pulmonary blood flow and systemic and pulmonary vascular dynamics. Pulmonary hypertension was induced by hypoxia, or infusion of the thromboxane analog (U-46619, 0.1 µg/kg/min, i.v.. In rats, chronic pulmonary hypertension was induced by monocrotaline.CK-165 (4 mg/kg, i.v. reduced pulmonary vascular resistance by 22±3 and 28±6% from baseline in hypoxia and thromboxane pig models, respectively (p<0.01 and 0.01, while mean arterial pressure also fell and heart rate rose slightly. When CK-165 was delivered via inhalation in the hypoxia model, pulmonary vascular resistance fell by 17±6% (p<0.05 while mean arterial pressure and heart rate were unchanged. In the monocrotaline model of chronic pulmonary hypertension, inhaled CK-165 resulted in a similar (18.0±3.8% reduction in right ventricular systolic pressure as compared with sildenafil (20.3±4.5%.Inhibition of smooth muscle myosin may be a novel therapeutic target for treatment of pulmonary hypertension.

  20. Lack of replication for the myosin-18B association with mathematical ability in independent cohorts

    Science.gov (United States)

    Pettigrew, K A; Fajutrao Valles, S F; Moll, K; Northstone, K; Ring, S; Pennell, C; Wang, C; Leavett, R; Hayiou-Thomas, M E; Thompson, P; Simpson, N H; Fisher, S E; Whitehouse, A J O; Snowling, M J; Newbury, D F; Paracchini, S

    2015-01-01

    Twin studies indicate that dyscalculia (or mathematical disability) is caused partly by a genetic component, which is yet to be understood at the molecular level. Recently, a coding variant (rs133885) in the myosin-18B gene was shown to be associated with mathematical abilities with a specific effect among children with dyslexia. This association represents one of the most significant genetic associations reported to date for mathematical abilities and the only one reaching genome-wide statistical significance. We conducted a replication study in different cohorts to assess the effect of rs133885 maths-related measures. The study was conducted primarily using the Avon Longitudinal Study of Parents and Children (ALSPAC), (N = 3819). We tested additional cohorts including the York Cohort, the Specific Language Impairment Consortium (SLIC) cohort and the Raine Cohort, and stratified them for a definition of dyslexia whenever possible. We did not observe any associations between rs133885 in myosin-18B and mathematical abilities among individuals with dyslexia or in the general population. Our results suggest that the myosin-18B variant is unlikely to be a main factor contributing to mathematical abilities. PMID:25778778

  1. Tilting and Wobble of Myosin V by High-Speed Single-Molecule Polarized Fluorescence Microscopy

    Science.gov (United States)

    Beausang, John F.; Shroder, Deborah Y.; Nelson, Philip C.; Goldman, Yale E.

    2013-01-01

    Myosin V is biomolecular motor with two actin-binding domains (heads) that take multiple steps along actin by a hand-over-hand mechanism. We used high-speed polarized total internal reflection fluorescence (polTIRF) microscopy to study the structural dynamics of single myosin V molecules that had been labeled with bifunctional rhodamine linked to one of the calmodulins along the lever arm. With the use of time-correlated single-photon counting technology, the temporal resolution of the polTIRF microscope was improved ∼50-fold relative to earlier studies, and a maximum-likelihood, multitrace change-point algorithm was used to objectively determine the times when structural changes occurred. Short-lived substeps that displayed an abrupt increase in rotational mobility were detected during stepping, likely corresponding to random thermal fluctuations of the stepping head while it searched for its next actin-binding site. Thus, myosin V harnesses its fluctuating environment to extend its reach. Additional, less frequent angle changes, probably not directly associated with steps, were detected in both leading and trailing heads. The high-speed polTIRF method and change-point analysis may be applicable to single-molecule studies of other biological systems. PMID:23528086

  2. Characteristics of myosin profile in human vastus lateralis muscle in relation to training background.

    Science.gov (United States)

    Zawadowska, B; Majerczak, J; Semik, D; Karasinski, J; Kolodziejski, L; Kilarski, W M; Duda, K; Zoladz, J A

    2004-01-01

    Twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg) of different training background were investigated and classified into three groups according to their physical activity and sport discipline: untrained students (group A), national and sub-national level endurance athletes (group B, 7.8+/-2.9 years of specialised training) and sprint-power athletes (group C, 12.8+/-8.7 years of specialised training). Muscle biopsies of vastus lateralis were analysed histochemically for mATPase and SDH activities, immunohistochemically for fast and slow myosin, and electrophoretically followed by Western immunoblotting for myosin heavy chain (MyHC) composition. Significant differences (Pski-jumping, volleyball, soccer and modern dance. Furthermore, the relative amount of the fastest MyHCIIX isoform in vastus lateralis muscle was significantly lower in the athletes from group C than in students (group A). We conclude that the myosin profile in the athletes belonging to group C was unfavourable for their sport disciplines. This could be the reason why those athletes did not reach international level despite of several years of training.

  3. A 35-Å movement of smooth muscle myosin on ADP release

    Science.gov (United States)

    Whittaker, Michael; Wilson-Kubalek, Elizabeth M.; Smith, Joseph E.; Faust, Lynn; Milligan, Ronald A.; Sweeney, H. Lee

    1995-12-01

    MYOSIN II crossbridges interact with F-actin producing power-strokes of around 100 Å (refs 1, 2), during which the products of ATP hydrolysis are released3-5. This has been postulated to involve an articulation of the myosin head (S1) on actin, or substantial conformational changes in S1 itself6-8. Small movements of the regulatory light chain have been detected (see, for example, refs 9, 10), but most data suggest that the bulk of S1 does not move on actin during crossbridge cycling8,11. Here we present three-dimensional maps of S1-decorated F-actin in the presence and absence of MgADP. The myosin motor domain is similar in both states but there are major orientational differences in the light-chain-binding domain. This domain acts as a rigid level arm12,13 pivoting about the end of the motor domain and swinging ~23°, resulting in a ~35-Å step. Small, nucleotide-mediated conformational changes in the motor domain14-16may thus be converted by the light-chain domain into large movement steps.

  4. Synthesis of biotinylated xestoquinone that retains inhibitory activity against Ca2+ ATPase of skeletal muscle myosin.

    Science.gov (United States)

    Nakamura, Mitsuhiro; Kakuda, Takahiko; Oba, Yuichi; Ojika, Makoto; Nakamura, Hideshi

    2003-07-17

    Xestoquinone isolated from a marine sponge binds to skeletal muscle myosin and inhibits its Ca(2+) ATPase activity. In this study, we first examined xestoquinone and its analogues to assess the relationships between structure and myosin Ca(2+) ATPase inhibitory activity. On the basis of the resultant data, we then designed a biotinylated xestoquinone analogue. Xestoquinone and its analogues were derived from extracts of the marine sponge Xestospongia sapra. Four xestoquinone analogues with a quinone structure significantly inhibited Ca(2+) ATPase activity. In contrast, four xestoquinone analogues in which the quinone structure was converted to a quinol dimethyl ether did not inhibit Ca(2+) ATPase activity. This suggests that the quinone moiety is essential for inhibitory activity. Then, we synthesized a biotinylated xestoquinone in which a biotin tag was introduced to a site far from the quinone moiety, and this molecule exhibited stronger inhibitory activity than that of xestoquinone. This biotinylated xestoquinone could be useful as a probe in studies of the xestoquinone-myosin binding mode.

  5. Molecular cloning, purification and characterisation of myosin of human lymphatic filarial parasite Brugia malayi.

    Science.gov (United States)

    Verma, S K; Bansal, I; Vedi, S; Saxena, J K; Katoch, V M; Bhattacharya, S M

    2008-02-01

    Global efforts have been made towards development of vaccine for prevention of lymphatic filariasis. However, lack of thorough knowledge about developmental biology and pathogenesis of filarial parasite restricts us from developing an effective vaccine. A limited number of immunodominant antigens of human lymphatic filariid Brugia malayi have been characterised; however, none of these recombinant antigens so far induced significant degree of protective immunity to challenge infection. In the present study, we identified a approximately 2.0 Kb cDNA clone by immunoscreening of cDNA library of adult female Brugia malayi. The nucleotide sequence of the identified clone showed 94.3% homology with C-terminal part of myosin heavy chain gene of Brugia malayi. This cDNA insert was sub-cloned into pET28b vector and expressed in BL21(DE3). The recombinant protein was purified to near homogeneity by immobilised metal affinity chromatography (IMAC) with yield of approximately 25 mg/l. The purified protein was recognised in western blot with anti-His tag antibody as also with the antibodies present in the sera of human W. bancrofti patients of all categories and infected/immunized rodent serum demonstrating its functional role. Recombinant myosin induced marked cellular immune response as observed by lymphoproliferation assay. The present findings demonstrate the usefulness of B. malayi recombinant myosin as vaccine candidate against human lymphatic filariasis.

  6. Differential activity of Drosophila Hox genes induces myosin expression and can maintain compartment boundaries.

    Directory of Open Access Journals (Sweden)

    Jesús R Curt

    Full Text Available Compartments are units of cell lineage that subdivide territories with different developmental potential. In Drosophila, the wing and haltere discs are subdivided into anterior and posterior (A/P compartments, which require the activity of Hedgehog, and into dorsal and ventral (D/V compartments, needing Notch signaling. There is enrichment in actomyosin proteins at the compartment boundaries, suggesting a role for these proteins in their maintenance. Compartments also develop in the mouse hindbrain rhombomeres, which are characterized by the expression of different Hox genes, a group of genes specifying different structures along their main axis of bilaterians. We show here that the Drosophila Hox gene Ultrabithorax can maintain the A/P and D/V compartment boundaries when Hedgehog or Notch signaling is compromised, and that the interaction of cells with and without Ultrabithorax expression induces high levels of non-muscle myosin II. In the absence of Ultrabithorax there is occasional mixing of cells from different segments. We also show a similar role in cell segregation for the Abdominal-B Hox gene. Our results suggest that the juxtaposition of cells with different Hox gene expression leads to their sorting out, probably through the accumulation of non-muscle myosin II at the boundary of the different cell territories. The increase in myosin expression seems to be a general mechanism used by Hox genes or signaling pathways to maintain the segregation of different groups of cells.

  7. Antidepressants and protein kinases: inhibition of Ca2+-regulated myosin phosphorylation by fluoxetine and iprindole.

    Science.gov (United States)

    Silver, P J; Sigg, E B; Moyer, J A

    1986-02-11

    The effects of several antidepressant and antipsychotic agents on Ca2+-calmodulin-regulated myosin light chain phosphorylation were evaluated. At a concentration of 100 microM, the antidepressant agents buproprion, mianserin and maprotiline were ineffective; zimelidine, desipramine and imipramine produced 40-50% inhibition; and iprindole and fluoxetine produced 75-90% inhibition. The efficacies of iprindole and fluoxetine were similar to the phenothiazine antipsychotics chlorpromazine and trifluoperazine. Clozapine, an atypical antipsychotic and the butyrophenone haloperidol were relatively ineffective as myosin light chain phosphorylation inhibitors. IC50 values of the most effective agents were: trifluoperazine 16 microM, fluoxetine 28 microM, chlorpromazine and iprindole 56 microM. As with trifluoperazine, inhibition of myosin phosphorylation by iprindole was completely attenuated in the presence of exogenous calmodulin. However, a significant component (30%) of the inhibitory effect of fluoxetine was not reversible with calmodulin. These results show that some antidepressant agents, most notably iprindole and fluoxetine, are capable of antagonizing a calmodulin-regulated protein kinase through calmodulin inhibition; and in the case of fluoxetine, through an additional calmodulin-independent mechanism.

  8. Dietary genistein enhances phosphorylation of regulatory myosin light chain in the myocardium of ovariectomized mice.

    Science.gov (United States)

    Schwab, Karima; Stein, Robert; Scheler, Christian; Theuring, Franz

    2012-07-01

    There is evidence that isoflavones, such as genistein, can directly or indirectly improve lipid profile and lower blood pressure and hence exert cardiovascular protection. It is further believed, that genistein attenuates vascular contraction and thus vascular tone and blood pressure through altering the phosphorylation of the regulatory myosin light chain (MLC) probably via the myosin light chain kinase (MLCK) or the RhoA pathway. However, the direct role of genistein in the myocardium is poorly reviewed. In this study, we investigated the impact of genistein on the cardiac proteome in ovariectomized female mice using a 2DE-MS approach. Dietary genistein intake considerably changed the abundance of several cytoskeletal and contractile proteins and enhanced the phosphorylation of MLC. The MLC phosphorylation was mediated through increased abundance of MLCK and inhibition of myosin light chain phosphatase latest known to be inversely regulated by RhoA. Contrary to others, in our model genistein did neither inhibit the cardiac MLCK, nor the cardiac RhoA pathway in vivo. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Myogenin, MyoD, and myosin expression after pharmacologically and surgically induced hypertrophy

    Science.gov (United States)

    Mozdziak, P. E.; Greaser, M. L.; Schultz, E.

    1998-01-01

    The relationship between myogenin or MyoD expression and hypertrophy of the rat soleus produced either by clenbuterol and 3,3', 5-triiodo-L-thyronine (CT) treatment or by surgical overload was examined. Mature female rats were subjected to surgical overload of the right soleus with the left soleus serving as a control. Another group received the same surgical treatment but were administered CT. Soleus muscles were harvested 4 wk after surgical overload and weighed. Myosin heavy chain isoforms were separated by using polyacrylamide gel electrophoresis while myogenin and MyoD expression were evaluated by Northern analysis. CT and functional overload increased soleus muscle weight. CT treatment induced the appearance of the fast type IIX myosin heavy chain isoform, depressed myogenin expression, and induced MyoD expression. However, functional overload did not alter myogenin or MyoD expression in CT-treated or non-CT-treated rats. Thus pharmacologically and surgically induced hypertrophy have differing effects on myogenin and MyoD expression, because their levels were associated with changes in myosin heavy chain composition (especially type IIX) rather than changes in muscle mass.

  10. PREFACE: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Saxena, Siddharth S.; Littlewood, P. B.

    2012-07-01

    make use of 'small' electrons packed to the highest possible density. These are by definition 'strongly correlated'. For example: good photovoltaics must be efficient optical absorbers, which means that photons will generate tightly bound electron-hole pairs (excitons) that must then be ionised at a heterointerface and transported to contacts; efficient solid state refrigeration depends on substantial entropy changes in a unit cell, with large local electrical or magnetic moments; efficient lighting is in a real sense the inverse of photovoltaics; the limit of an efficient battery is a supercapacitor employing mixed valent ions; fuel cells and solar to fuel conversion require us to understand electrochemistry on the scale of a single atom; and we already know that the only prospect for effective high temperature superconductivity involves strongly correlated materials. Even novel IT technologies are now seen to have value not just for novel function but also for efficiency. While strongly correlated electron systems continue to excite researchers and the public alike due to the fundamental science issues involved, it seems increasingly likely that support for the science will be leveraged by its impact on energy and sustainability. Strongly correlated electron systems contents Strongly correlated electron systemsSiddharth S Saxena and P B Littlewood Magnetism, f-electron localization and superconductivity in 122-type heavy-fermion metalsF Steglich, J Arndt, O Stockert, S Friedemann, M Brando, C Klingner, C Krellner, C Geibel, S Wirth, S Kirchner and Q Si High energy pseudogap and its evolution with doping in Fe-based superconductors as revealed by optical spectroscopyN L Wang, W Z Hu, Z G Chen, R H Yuan, G Li, G F Chen and T Xiang Structural investigations on YbRh2Si2: from the atomic to the macroscopic length scaleS Wirth, S Ernst, R Cardoso-Gil, H Borrmann, S Seiro, C Krellner, C Geibel, S Kirchner, U Burkhardt, Y Grin and F Steglich Confinement of chiral magnetic

  11. Properties of a Bound Polaron under a Perpendicular Magnetic Field

    International Nuclear Information System (INIS)

    Liu Jia; Chen Ziyu; Xiao Jinglin; Huo Shufen

    2007-01-01

    We investigate the influence of a perpendicular magnetic field on a bound polaron near the interface of a polar-polar semiconductor with Rashba effect. The external magnetic field strongly changes the ground state binding energy of the polaron and the Rashba spin-orbit (SO) interaction originating from the inversion asymmetry in the heterostructure splits the ground state binding energy of the bound polaron. In this paper, we have shown how the ground state binding energy will be with the change of the external magnetic field, the location of a single impurity, the wave vector of the electron and the electron areal density, taking into account the SO coupling. Due to the presence of the phonons, whose energy gives negative contribution to the polaron's, the spin-splitting states of the bound polaron are more stable, and we find that in the condition of week magnetic field, the Zeeaman effect can be neglected.

  12. Soft-bound synaptic plasticity increases storage capacity.

    Directory of Open Access Journals (Sweden)

    Mark C W van Rossum

    Full Text Available Accurate models of synaptic plasticity are essential to understand the adaptive properties of the nervous system and for realistic models of learning and memory. Experiments have shown that synaptic plasticity depends not only on pre- and post-synaptic activity patterns, but also on the strength of the connection itself. Namely, weaker synapses are more easily strengthened than already strong ones. This so called soft-bound plasticity automatically constrains the synaptic strengths. It is known that this has important consequences for the dynamics of plasticity and the synaptic weight distribution, but its impact on information storage is unknown. In this modeling study we introduce an information theoretic framework to analyse memory storage in an online learning setting. We show that soft-bound plasticity increases a variety of performance criteria by about 18% over hard-bound plasticity, and likely maximizes the storage capacity of synapses.

  13. Strongly Correlated Topological Insulators

    Science.gov (United States)

    2016-02-03

    Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or

  14. Strong Cosmic Censorship

    Science.gov (United States)

    Isenberg, James

    2017-01-01

    The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his `Strong Cosmic Censorship Conjecture`) that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that ``AVTD behavior'' (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying model versions of Strong Cosmic Censorship in that family. I discuss some of the history of Strong Cosmic Censorship, and then discuss what is known about AVTD behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss recent results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. I also comment on some of the recent work on ``Weak Null Singularities'', and how this relates to Strong Cosmic Censorship.

  15. The algebras of bounded and essentially bounded Lebesgue measurable functions

    Directory of Open Access Journals (Sweden)

    Mortini Raymond

    2017-04-01

    Full Text Available Let X be a set in ℝn with positive Lebesgue measure. It is well known that the spectrum of the algebra L∞(X of (equivalence classes of essentially bounded, complex-valued, measurable functions on X is an extremely disconnected compact Hausdorff space.We show, by elementary methods, that the spectrum M of the algebra ℒb(X, ℂ of all bounded measurable functions on X is not extremely disconnected, though totally disconnected. Let ∆ = { δx : x ∈ X} be the set of point evaluations and let g be the Gelfand topology on M. Then (∆, g is homeomorphic to (X, Τdis,where Tdis is the discrete topology. Moreover, ∆ is a dense subset of the spectrum M of ℒb(X, ℂ. Finally, the hull h(I, (which is homeomorphic to M(L∞(X, of the ideal of all functions in ℒb(X, ℂ vanishing almost everywhere on X is a nowhere dense and extremely disconnected subset of the Corona M \\ ∆ of ℒb(X, ℂ.

  16. Voronoi Diagrams Without Bounding Boxes

    Science.gov (United States)

    Sang, E. T. K.

    2015-10-01

    We present a technique for presenting geographic data in Voronoi diagrams without having to specify a bounding box. The method restricts Voronoi cells to points within a user-defined distance of the data points. The mathematical foundation of the approach is presented as well. The cell clipping method is particularly useful for presenting geographic data that is spread in an irregular way over a map, as for example the Dutch dialect data displayed in Figure 2. The automatic generation of reasonable cell boundaries also makes redundant a frequently used solution to this problem that requires data owners to specify region boundaries, as in Goebl (2010) and Nerbonne et al (2011).

  17. Sensitivity analysis using probability bounding

    International Nuclear Information System (INIS)

    Ferson, Scott; Troy Tucker, W.

    2006-01-01

    Probability bounds analysis (PBA) provides analysts a convenient means to characterize the neighborhood of possible results that would be obtained from plausible alternative inputs in probabilistic calculations. We show the relationship between PBA and the methods of interval analysis and probabilistic uncertainty analysis from which it is jointly derived, and indicate how the method can be used to assess the quality of probabilistic models such as those developed in Monte Carlo simulations for risk analyses. We also illustrate how a sensitivity analysis can be conducted within a PBA by pinching inputs to precise distributions or real values

  18. Determining Normal-Distribution Tolerance Bounds Graphically

    Science.gov (United States)

    Mezzacappa, M. A.

    1983-01-01

    Graphical method requires calculations and table lookup. Distribution established from only three points: mean upper and lower confidence bounds and lower confidence bound of standard deviation. Method requires only few calculations with simple equations. Graphical procedure establishes best-fit line for measured data and bounds for selected confidence level and any distribution percentile.

  19. Strong Arcwise Connectedness

    OpenAIRE

    Espinoza, Benjamin; Gartside, Paul; Kovan-Bakan, Merve; Mamatelashvili, Ana

    2012-01-01

    A space is `n-strong arc connected' (n-sac) if for any n points in the space there is an arc in the space visiting them in order. A space is omega-strong arc connected (omega-sac) if it is n-sac for all n. We study these properties in finite graphs, regular continua, and rational continua. There are no 4-sac graphs, but there are 3-sac graphs and graphs which are 2-sac but not 3-sac. For every n there is an n-sac regular continuum, but no regular continuum is omega-sac. There is an omega-sac ...

  20. Abortion: Strong's counterexamples fail

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2009-01-01

    This paper shows that the counterexamples proposed by Strong in 2008 in the Journal of Medical Ethics to Marquis's argument against abortion fail. Strong's basic idea is that there are cases--for example, terminally ill patients--where killing an adult human being is prima facie seriously morally......'s scenarios have some valuable future or admitted that killing them is not seriously morally wrong. Finally, if "valuable future" is interpreted as referring to objective standards, one ends up with implausible and unpalatable moral claims....

  1. Observational Bounds on Cosmic Doomsday

    Energy Technology Data Exchange (ETDEWEB)

    Shmakova, Marina

    2003-07-11

    Recently it was found, in a broad class of models, that the dark energy density may change its sign during the evolution of the universe. This may lead to a global collapse of the universe within the time t{sub c} {approx} 10{sup 10}-10{sup 11} years. Our goal is to find what bounds on the future lifetime of the universe can be placed by the next generation of cosmological observations. As an example, we investigate the simplest model of dark energy with a linear potential V({phi}) = V{sub 0}(1 + {alpha}{phi}). This model can describe the present stage of acceleration of the universe if {alpha} is small enough. However, eventually the field {phi} rolls down, V({phi}) becomes negative, and the universe collapses. The existing observational data indicate that the universe described by this model will collapse not earlier than t{sub c} {approx_equal} 10 billion years from the present moment. We show that the data from SNAP and Planck satellites may extend the bound on the ''doomsday'' time to tc 40 billion years at the 95% confidence level.

  2. Quantum bounds on Bell inequalities

    Science.gov (United States)

    Pál, Károly F.; Vértesi, Tamás

    2009-02-01

    We have determined the maximum quantum violation of 241 tight bipartite Bell inequalities with up to five two-outcome measurement settings per party by constructing the appropriate measurement operators in up to six-dimensional complex and eight-dimensional real-component Hilbert spaces using numerical optimization. Out of these inequalities 129 have been introduced here. In 43 cases higher-dimensional component spaces gave larger violation than qubits, and in three occasions the maximum was achieved with six-dimensional spaces. We have also calculated upper bounds on these Bell inequalities using a method proposed recently. For all but 20 inequalities the best solution found matched the upper bound. Surprisingly, the simplest inequality of the set examined, with only three measurement settings per party, was not among them, despite the high dimensionality of the Hilbert space considered. We also computed detection threshold efficiencies for the maximally entangled qubit pair. These could be lowered in several instances if degenerate measurements were also allowed.

  3. Physics of Strongly Coupled Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kraeft, Wolf-Dietrich [Universitat Rostock (Germany)

    2007-07-15

    Strongly coupled plasmas (or non-ideal plasmas) are multi-component charged many-particle systems, in which the mean value of the potential energy of the system is of the same order as or even higher than the mean value of the kinetic energy. The constituents are electrons, ions, atoms and molecules. Dusty (or complex) plasmas contain still mesoscopic (multiply charged) particles. In such systems, the effects of strong coupling (non-ideality) lead to considerable deviations of physical properties from the corresponding properties of ideal plasmas, i.e., of plasmas in which the mean kinetic energy is essentially larger than the mean potential energy. For instance, bound state energies become density dependent and vanish at higher densities (Mott effect) due to the interaction of the pair with the surrounding particles. Non-ideal plasmas are of interest both for general scientific reasons (including, for example, astrophysical questions), and for technical applications such as inertially confined fusion. In spite of great efforts both experimentally and theoretically, satisfactory information on the physical properties of strongly coupled plasmas is not at hand for any temperature and density. For example, the theoretical description of non-ideal plasmas is possible only at low densities/high temperatures and at extremely high densities (high degeneracy). For intermediate degeneracy, however, numerical experiments have to fill the gap. Experiments are difficult in the region of 'warm dense matter'. The monograph tries to present the state of the art concerning both theoretical and experimental attempts. It mainly includes results of the work performed in famous Russian laboratories in recent decades. After outlining basic concepts (chapter 1), the generation of plasmas is considered (chapter 2, chapter 3). Questions of partial (chapter 4) and full ionization (chapter 5) are discussed including Mott transition and Wigner crystallization. Electrical and

  4. A strong comeback

    International Nuclear Information System (INIS)

    Marier, D.

    1992-01-01

    This article presents the results of a financial rankings survey which show a strong economic activity in the independent energy industry. The topics of the article include advisor turnover, overseas banks, and the increase in public offerings. The article identifies the top project finance investors for new projects and restructurings and rankings for lenders

  5. Holography, Dimensional Reduction and the Bekenstein Bound

    Science.gov (United States)

    Bak, Dongsu; Yee, Ho-Ung

    2004-04-01

    We consider dimensional reduction of the lightlike holography of the covariant entropy bound from D+1 dimensional geometry of M × S1 to the D dimensional geometry M. With a warping factor, the local Bekenstein bound in D+1 dimensions leads to a more refined form of the bound from the D dimensional view point. With this new local Bekenstein bound, it is quite possible to saturate the lightlike holography even with nonvanishing expansion rate. With a Kaluza-Klein gauge field, the dimensional reduction implies a stronger bound where the energy momentum tensor contribution is replaced by the energy momentum tensor with the electromagnetic contribution subtracted.

  6. Interaction of c-Cbl with myosin IIA regulates Bleb associated macropinocytosis of Kaposi's sarcoma-associated herpesvirus.

    Science.gov (United States)

    Valiya Veettil, Mohanan; Sadagopan, Sathish; Kerur, Nagaraj; Chakraborty, Sayan; Chandran, Bala

    2010-12-23

    KSHV is etiologically associated with Kaposi's sarcoma (KS), an angioproliferative endothelial cell malignancy. Macropinocytosis is the predominant mode of in vitro entry of KSHV into its natural target cells, human dermal microvascular endothelial (HMVEC-d) cells. Although macropinocytosis is known to be a major route of entry for many viruses, the molecule(s) involved in the recruitment and integration of signaling early during macropinosome formation is less well studied. Here we demonstrate that tyrosine phosphorylation of the adaptor protein c-Cbl is required for KSHV induced membrane blebbing and macropinocytosis. KSHV induced the tyrosine phosphorylation of c-Cbl as early as 1 min post-infection and was recruited to the sites of bleb formation. Infection also led to an increase in the interaction of c-Cbl with PI3-K p85 in a time dependent manner. c-Cbl shRNA decreased the formation of KSHV induced membrane blebs and macropinocytosis as well as virus entry. Immunoprecipitation of c-Cbl followed by mass spectrometry identified the interaction of c-Cbl with a novel molecular partner, non-muscle myosin heavy chain IIA (myosin IIA), in bleb associated macropinocytosis. Phosphorylated c-Cbl colocalized with phospho-myosin light chain II in the interior of blebs of infected cells and this interaction was abolished by c-Cbl shRNA. Studies with the myosin II inhibitor blebbistatin demonstrated that myosin IIA is a biologically significant component of the c-Cbl signaling pathway and c-Cbl plays a new role in the recruitment of myosin IIA to the blebs during KSHV infection. Myosin II associates with actin in KSHV induced blebs and the absence of actin and myosin ubiquitination in c-Cbl ShRNA cells suggested that c-Cbl is also responsible for the ubiquitination of these proteins in the infected cells. This is the first study demonstrating the role of c-Cbl in viral entry as well as macropinocytosis, and provides the evidence that a signaling complex containing c

  7. Interaction of c-Cbl with myosin IIA regulates Bleb associated macropinocytosis of Kaposi's sarcoma-associated herpesvirus.

    Directory of Open Access Journals (Sweden)

    Mohanan Valiya Veettil

    2010-12-01

    Full Text Available KSHV is etiologically associated with Kaposi's sarcoma (KS, an angioproliferative endothelial cell malignancy. Macropinocytosis is the predominant mode of in vitro entry of KSHV into its natural target cells, human dermal microvascular endothelial (HMVEC-d cells. Although macropinocytosis is known to be a major route of entry for many viruses, the molecule(s involved in the recruitment and integration of signaling early during macropinosome formation is less well studied. Here we demonstrate that tyrosine phosphorylation of the adaptor protein c-Cbl is required for KSHV induced membrane blebbing and macropinocytosis. KSHV induced the tyrosine phosphorylation of c-Cbl as early as 1 min post-infection and was recruited to the sites of bleb formation. Infection also led to an increase in the interaction of c-Cbl with PI3-K p85 in a time dependent manner. c-Cbl shRNA decreased the formation of KSHV induced membrane blebs and macropinocytosis as well as virus entry. Immunoprecipitation of c-Cbl followed by mass spectrometry identified the interaction of c-Cbl with a novel molecular partner, non-muscle myosin heavy chain IIA (myosin IIA, in bleb associated macropinocytosis. Phosphorylated c-Cbl colocalized with phospho-myosin light chain II in the interior of blebs of infected cells and this interaction was abolished by c-Cbl shRNA. Studies with the myosin II inhibitor blebbistatin demonstrated that myosin IIA is a biologically significant component of the c-Cbl signaling pathway and c-Cbl plays a new role in the recruitment of myosin IIA to the blebs during KSHV infection. Myosin II associates with actin in KSHV induced blebs and the absence of actin and myosin ubiquitination in c-Cbl ShRNA cells suggested that c-Cbl is also responsible for the ubiquitination of these proteins in the infected cells. This is the first study demonstrating the role of c-Cbl in viral entry as well as macropinocytosis, and provides the evidence that a signaling complex

  8. Capacity Bounds for Parallel Optical Wireless Channels

    KAUST Repository

    Chaaban, Anas

    2016-01-01

    A system consisting of parallel optical wireless channels with a total average intensity constraint is studied. Capacity upper and lower bounds for this system are derived. Under perfect channel-state information at the transmitter (CSIT), the bounds have to be optimized with respect to the power allocation over the parallel channels. The optimization of the lower bound is non-convex, however, the KKT conditions can be used to find a list of possible solutions one of which is optimal. The optimal solution can then be found by an exhaustive search algorithm, which is computationally expensive. To overcome this, we propose low-complexity power allocation algorithms which are nearly optimal. The optimized capacity lower bound nearly coincides with the capacity at high SNR. Without CSIT, our capacity bounds lead to upper and lower bounds on the outage probability. The outage probability bounds meet at high SNR. The system with average and peak intensity constraints is also discussed.

  9. Alternative exon-encoding regions of Locusta migratoria muscle myosin modulate the pH dependence of ATPase activity.

    Science.gov (United States)

    Li, J; Lu, Z; He, J; Chen, Q; Wang, X; Kang, L; Li, X-D

    2016-12-01

    Whereas the vertebrate muscle myosin heavy chains (MHCs) are encoded by a family of Mhc genes, most insects examined to date contain a single Mhc gene and produce all of the different MHC isoforms by alternative RNA splicing. Here, we found that the migratory locust, Locusta migratoria, has one Mhc gene, which contains 41 exons, including five alternative exclusive exons and one differently included penultimate exon, and potentially encodes 360 MHC isoforms. From the adult L. migratoria, we identified 14 MHC isoforms (including two identical isoforms): four from flight muscle (the thorax dorsal longitudinal muscle), three from jump muscle (the hind leg extensor tibiae muscle) and seven from the abdominal intersegmental muscle. We purified myosins from flight muscle and jump muscle and characterized their motor activities. At neutral pH, the flight and the jump muscle myosins displayed similar levels of in vitro actin-gliding activity, whereas the former had a slightly higher actin-activated ATPase activity than the latter. Interestingly, the pH dependences of the actin-activated ATPase activity of these two myosins are different. Because the dominant MHC isoforms in these two muscles are identical except for the two alternative exon-encoding regions, we propose that these two alternative regions modulate the pH dependence of L. migratoria muscle myosin. © 2016 The Royal Entomological Society.

  10. On order bounded subsets of locally solid Riesz spaces | Hong ...

    African Journals Online (AJOL)

    In a topological Riesz space there are two types of bounded subsets: order bounded subsets and topologically bounded subsets. It is natural to ask (1) whether an order bounded subset is topologically bounded and (2) whether a topologically bounded subset is order bounded. A classical result gives a partial answer to (1) ...

  11. VORONOI DIAGRAMS WITHOUT BOUNDING BOXES

    Directory of Open Access Journals (Sweden)

    E. T. K. Sang

    2015-10-01

    Full Text Available We present a technique for presenting geographic data in Voronoi diagrams without having to specify a bounding box. The method restricts Voronoi cells to points within a user-defined distance of the data points. The mathematical foundation of the approach is presented as well. The cell clipping method is particularly useful for presenting geographic data that is spread in an irregular way over a map, as for example the Dutch dialect data displayed in Figure 2. The automatic generation of reasonable cell boundaries also makes redundant a frequently used solution to this problem that requires data owners to specify region boundaries, as in Goebl (2010 and Nerbonne et al (2011.

  12. Cosmological bounds on neutrino statistics

    Science.gov (United States)

    de Salas, P. F.; Gariazzo, S.; Laveder, M.; Pastor, S.; Pisanti, O.; Truong, N.

    2018-03-01

    We consider the phenomenological implications of the violation of the Pauli exclusion principle for neutrinos, focusing on cosmological observables such as the spectrum of Cosmic Microwave Background anisotropies, Baryon Acoustic Oscillations and the primordial abundances of light elements. Neutrinos that behave (at least partly) as bosonic particles have a modified equilibrium distribution function that implies a different influence on the evolution of the Universe that, in the case of massive neutrinos, can not be simply parametrized by a change in the effective number of neutrinos. Our results show that, despite the precision of the available cosmological data, only very weak bounds can be obtained on neutrino statistics, disfavouring a more bosonic behaviour at less than 2σ.

  13. Fundamental Bounds on MIMO Antennas

    Science.gov (United States)

    Ehrenborg, Casimir; Gustafsson, Mats

    2018-01-01

    Antenna current optimization is often used to analyze the optimal performance of antennas. Antenna performance can be quantified in e.g., minimum Q-factor and efficiency. The performance of MIMO antennas is more involved and, in general, a single parameter is not sufficient to quantify it. Here, the capacity of an idealized channel is used as the main performance quantity. An optimization problem in the current distribution for optimal capacity, measured in spectral efficiency, given a fixed Q-factor and efficiency is formulated as a semi-definite optimization problem. A model order reduction based on characteristic and energy modes is employed to improve the computational efficiency. The performance bound is illustrated by solving the optimization problem numerically for rectangular plates and spherical shells.

  14. Spectral computations for bounded operators

    CERN Document Server

    Ahues, Mario; Limaye, Balmohan

    2001-01-01

    Exact eigenvalues, eigenvectors, and principal vectors of operators with infinite dimensional ranges can rarely be found. Therefore, one must approximate such operators by finite rank operators, then solve the original eigenvalue problem approximately. Serving as both an outstanding text for graduate students and as a source of current results for research scientists, Spectral Computations for Bounded Operators addresses the issue of solving eigenvalue problems for operators on infinite dimensional spaces. From a review of classical spectral theory through concrete approximation techniques to finite dimensional situations that can be implemented on a computer, this volume illustrates the marriage of pure and applied mathematics. It contains a variety of recent developments, including a new type of approximation that encompasses a variety of approximation methods but is simple to verify in practice. It also suggests a new stopping criterion for the QR Method and outlines advances in both the iterative refineme...

  15. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  16. Plasmons in strong superconductors

    International Nuclear Information System (INIS)

    Baldo, M.; Ducoin, C.

    2011-01-01

    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  17. Experimental Observation of Strongly Bound Dimers of Sulfuric Acid: Application to Nucleation in the Atmosphere

    DEFF Research Database (Denmark)

    Petaja, Tuukka; Sipila, Mikko; Paasonen, Pauli

    2011-01-01

    Sulfuric acid is a key compound in atmospheric nucleation. Here we report on the observation of a close-to-collision-limited sulfuric acid dimer formation in atmospherically relevant laboratory conditions in the absence of measurable quantities of ammonia or organics. The observed dimer formation...... compound(s) with (a) concentration(s) high enough to prevent the dimer evaporation. Such a stabilizing compound should be abundant enough in any natural environment and would therefore not limit the formation of sulfuric acid dimers in the atmosphere....

  18. Clinical assessment of serum myosin light chain I in patients with dilated cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Tsuda, Takashi; Izumi, Tohru; Shibata, Akira (Niigata Univ. (Japan). School of Medicine)

    1992-08-01

    Serum cardiac myosin light chain I (LCI) levels were quantitated using a radioimmunoassay kit in patients suspected of dilated cardiomyopathy (DCM). In this study, 55 patients were evaluated between 1986 and 1991. They were composed of 40 males and 15 females, and their age was 27-75 years (51[+-]11 years). The patients with renal dysfunction were excluded due to their serum creatinine levels (>2.0 mg/dl). After cardiac catheterization, endomyocardial biopsy and echocardiography, 44 patients were diagnosed as DCM, 2 as ischemic heart disease, 2 as chronic myocarditis, 1 as restrictive cardiomyopathy, 1 as dilated hypertrophic cardiomyopathy, 1 as cardiac amyloidosis, 2 as myopathy, 1 as polymyositis and 1 as hypothyroidism. Only two patients with DCM had elevated LCI. Besides, two patients with myopathy or hypothyroidism had elevated LCI. In the follow-up, one patient died suddenly 6 months later and another showed normal value of LCI four years later. LCI elevation in DCM was not related to either the severity of heart failure or cardiac function and it showed no finding of [sup 201]Tl myocardial defect or elevated CPK. The mechanism for elevated LCI in myopathy is related to a crossreaction with myosin light chain in the skeletal muscle. In hypothyroidism, it may be related to decreased clearance of normal LCI concentration or increased myosin light chain from damaged skeletal muscle. In conclusion, it is evident that the measurement of LCI is not helpful in clinical assessment of patients with DCM, but may be useful in detection of secondary cardiomyopathy. (author).

  19. Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation.

    Science.gov (United States)

    Bunda, Jordan; Gittings, William; Vandenboom, Rene

    2018-01-30

    Phosphorylation of the myosin regulatory light chain (RLC) by skeletal myosin light chain kinase (skMLCK) potentiates rodent fast twitch muscle but is an ATP-requiring process. Our objective was to investigate the effect of skMLCK-catalyzed RLC phosphorylation on the energetic cost of contraction and the contractile economy (ratio of mechanical output to metabolic input) of mouse fast twitch muscle in vitro (25°C). To this end, extensor digitorum longus (EDL) muscles from wild-type (WT) and from skMLCK-devoid (skMLCK -/- ) mice were subjected to repetitive low-frequency stimulation (10 Hz for 15 s) to produce staircase potentiation of isometric twitch force, after which muscles were quick frozen for determination of high-energy phosphate consumption (HEPC). During stimulation, WT muscles displayed significant potentiation of isometric twitch force while skMLCK -/- muscles did not (i.e. 23% versus 5% change, respectively). Consistent with this, RLC phosphorylation was increased ∼3.5-fold from the unstimulated control value in WT but not in skMLCK -/- muscles. Despite these differences, the HEPC of WT muscles was not greater than that of skMLCK -/- muscles. As a result of the increased contractile output relative to HEPC, the calculated contractile economy of WT muscles was greater than that of skMLCK -/- muscles. Thus, our results suggest that skMLCK-catalyzed phosphorylation of the myosin RLC increases the contractile economy of WT mouse EDL muscle compared with skMLCK -/- muscles without RLC phosphorylation. © 2018. Published by The Company of Biologists Ltd.

  20. Formation of contractile networks and fibers in the medial cell cortex through myosin-II turnover, contraction, and stress-stabilization.

    Science.gov (United States)

    Nie, Wei; Wei, Ming-Tzo; Ou-Yang, H Daniel; Jedlicka, Sabrina S; Vavylonis, Dimitrios

    2015-01-01

    The morphology of adhered cells depends crucially on the formation of a contractile meshwork of parallel and cross-linked fibers along the contacting surface. The motor activity and minifilament assembly of non-muscle myosin-II is an important component of cortical cytoskeletal remodeling during mechanosensing. We used experiments and computational modeling to study cortical myosin-II dynamics in adhered cells. Confocal microscopy was used to image the medial cell cortex of HeLa cells stably expressing myosin regulatory light chain tagged with GFP (MRLC-GFP). The distribution of MRLC-GFP fibers and focal adhesions was classified into three types of network morphologies. Time-lapse movies show: myosin foci appearance and disappearance; aligning and contraction; stabilization upon alignment. Addition of blebbistatin, which perturbs myosin motor activity, leads to a reorganization of the cortical networks and to a reduction of contractile motions. We quantified the kinetics of contraction, disassembly and reassembly of myosin networks using spatio-temporal image correlation spectroscopy (STICS). Coarse-grained numerical simulations include bipolar minifilaments that contract and align through specified interactions as basic elements. After assuming that minifilament turnover decreases with increasing contractile stress, the simulations reproduce stress-dependent fiber formation in between focal adhesions above a threshold myosin concentration. The STICS correlation function in simulations matches the function measured in experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness. © 2015 Wiley Periodicals, Inc.

  1. Metastasis-associated protein Mts1 (S100A4) inhibits CK2-mediated phosphorylation and self-assembly of the heavy chain of nonmuscle myosin

    DEFF Research Database (Denmark)

    Kriajevska, M; Bronstein, I B; Scott, D J

    2000-01-01

    of Mts1. The short C-terminal fragment of the myosin heavy chain was totally soluble in the presence of an equimolar amount of Mts1 at low ionic conditions (50 mM NaCl). Depolymerization was found to be calcium-dependent and could be blocked by EGTA. Our data suggest that Mts1 can increase myosin...... a regulatory role in the myosin assembly. In the presence of calcium, Mts1 binds at the C-terminal end of the myosin heavy chain close to the site of phosphorylation by protein kinase CK2 (Ser1944). In the present study, we have shown that interaction of Mts1 with the human platelet myosin or C......-terminal fragment of the myosin heavy chain inhibits phosphorylation of the myosin heavy chain by protein kinase CK2 in vitro. Mts1 might also bind directly the beta subunit of protein kinase CK2, thereby modifying the enzyme activity. Our results indicate that myosin oligomers were disassembled in the presence...

  2. Effects of BTS (N-benzyl-p-toluene sulphonamide), an inhibitor for myosin-actin interaction, on myofibrillogenesis in skeletal muscle cells in culture.

    Science.gov (United States)

    Kagawa, Maiko; Sato, Naruki; Obinata, Takashi

    2006-11-01

    Actin filaments align around myosin filaments in the correct polarity and in a hexagonal arrangement to form cross-striated structures. It has been postulated that this myosin-actin interaction is important in the initial phase of myofibrillogenesis. It was previously demonstrated that an inhibitor of actin-myosin interaction, BDM (2,3-butanedione monoxime), suppresses myofibril formation in muscle cells in culture. However, further study showed that BDM also exerts several additional effects on living cells. In this study, we further examined the role of actin-myosin interaction in myofibril assembly in primary cultures of chick embryonic skeletal muscle by applying a more specific inhibitor, BTS (N-benzyl-p-toluene sulphonamide), of myosin ATPase and actin-myosin interaction. The assembly of sarcomeric structures from myofibrillar proteins was examined by immunocytochemical methods with the application of BTS to myotubes just after fusion. Addition of BTS (10-50 microM) significantly suppressed the organization of actin and myosin into cross-striated structures. BTS also interfered in the organization of alpha-actinin, C-protein (or MyBP-C), and connectin (or titin) into ordered striated structures, though the sensitivity was less. Moreover, when myotubes cultured in the presence of BTS were transferred to a control medium, sarcomeric structures were formed in 2-3 days, indicating that the inhibitory effect of BTS on myotubes is reversible. These results show that actin-myosin interaction plays a critical role in the process of myofibrillogenesis.

  3. At the Start of the Sarcomere: A Previously Unrecognized Role for Myosin Chaperones and Associated Proteins during Early Myofibrillogenesis

    Directory of Open Access Journals (Sweden)

    J. Layne Myhre

    2012-01-01

    Full Text Available The development of striated muscle in vertebrates requires the assembly of contractile myofibrils, consisting of highly ordered bundles of protein filaments. Myofibril formation occurs by the stepwise addition of complex proteins, a process that is mediated by a variety of molecular chaperones and quality control factors. Most notably, myosin of the thick filament requires specialized chaperone activity during late myofibrillogenesis, including that of Hsp90 and its cofactor, Unc45b. Unc45b has been proposed to act exclusively as an adaptor molecule, stabilizing interactions between Hsp90 and myosin; however, recent discoveries in zebrafish and C. elegans suggest the possibility of an earlier role for Unc45b during myofibrillogenesis. This role may involve functional control of nonmuscle myosins during the earliest stages of myogenesis, when premyofibril scaffolds are first formed from dynamic cytoskeletal actin. This paper will outline several lines of evidence that converge to build a model for Unc45b activity during early myofibrillogenesis.

  4. Stabilization of the Central Part of Tropomyosin Molecule Alters the Ca2+-sensitivity of Actin-Myosin Interaction.

    Science.gov (United States)

    Shchepkin, D V; Matyushenko, A M; Kopylova, G V; Artemova, N V; Bershitsky, S Y; Tsaturyan, A K; Levitsky, D I

    2013-07-01

    We show that the mutations D137L and G126R, which stabilize the central part of the tropomyosin (Tm) molecule, increase both the maximal sliding velocity of the regulated actin filaments in the in vitro motility assay at high Са(2+) concentrations and the Са(2+)-sensitivity of the actin-myosin interaction underlying this sliding. Based on an analysis of the recently published data on the structure of the actin-Tm-myosin complex, we suppose that the physiological effects of these mutations in Tm can be accounted for by their influence on the interactions between the central part of Tm and certain sites of the myosin head.

  5. Harmonic Force Spectroscopy measures load-dependent kinetics of individual human β-cardiac myosin molecules

    DEFF Research Database (Denmark)

    Sung, Jongmin; Nag, Suman; Mortensen, Kim

    2015-01-01

    Molecular motors are responsible for numerous cellular processes from cargo transport to heart contraction. Their interactions with other cellular components are often transient and exhibit kinetics that depend on load. Here, we measure such interactions using ‘harmonic force spectroscopy....... The protocol accumulates statistics fast enough to deliver single-molecule results from single-molecule experiments. We demonstrate the method’s performance by measuring the force-dependent kinetics of individual human b-cardiac myosin molecules interacting with an actin filament at physiological ATP...

  6. Sarcomeric myosin heavy chain is coded by a highly conserved multigene family.

    OpenAIRE

    Nguyen, H T; Gubits, R M; Wydro, R M; Nadal-Ginard, B

    1982-01-01

    pMHC25, a recombinant plasmid containing myosin heavy chain (MHC) cDNA sequences from differentiated myotubes of the L6E9 rat cell line, has been shown to hybridize to all sarcomeric MHC mRNAs so far tested but not to nonsarcomeric MHC mRNAs. In addition, pMHC25 hybridizes to multiple restriction endonuclease-digested fragments of rat genomic DNA corresponding to different MHC genomic sequences. Thus, the MHC gene represented by pMHC25 is a member of a sarcomeric MHC multigene family that has...

  7. Characteristics of myosin profile in human vastus lateralis muscle in relation to training background.

    Directory of Open Access Journals (Sweden)

    J A Zoladz

    2004-10-01

    Full Text Available Twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg of different training background were investigated and classified into three groups according to their physical activity and sport discipline: untrained students (group A, national and sub-national level endurance athletes (group B, 7.8+/-2.9 years of specialised training and sprint-power athletes (group C, 12.8+/-8.7 years of specialised training. Muscle biopsies of vastus lateralis were analysed histochemically for mATPase and SDH activities, immunohistochemically for fast and slow myosin, and electrophoretically followed by Western immunoblotting for myosin heavy chain (MyHC composition. Significant differences (P<0.05 regarding composition of muscle fibre types and myosin heavy chains were found only between groups A (41.7+/-1.6% of MyHCI, 40.8+/-4.0% of MyHCIIA and 17.5+/-4.0% of MyHCIIX and B (64.3+/-0.8% of MyHCI, 34.0+/-1.4% of MyHCIIA and 1.7+/-1.4% of MyHCIIX and groups A and C (59.6+/-1.6% of MyHCI, 37.2+/-1.3% of MyHCIIA and 3.2+/-1.3% of MyHCIIX. Unexpectedly, endurance athletes (group B such as long-distance runners, cyclists and cross country skiers, did not differ from the athletes representing short term, high power output sports (group C such as ice hockey, karate, ski-jumping, volleyball, soccer and modern dance. Furthermore, the relative amount of the fastest MyHCIIX isoform in vastus lateralis muscle was significantly lower in the athletes from group C than in students (group A. We conclude that the myosin profile in the athletes belonging to group C was unfavourable for their sport disciplines. This could be the reason why those athletes did not reach international level despite of several years of training.

  8. Comparative single-molecule and ensemble myosin enzymology: sulfoindocyanine ATP and ADP derivatives.

    OpenAIRE

    Oiwa, K; Eccleston, J F; Anson, M; Kikumoto, M; Davis, C T; Reid, G P; Ferenczi, M A; Corrie, J E; Yamada, A; Nakayama, H; Trentham, D R

    2000-01-01

    Single-molecule and macroscopic reactions of fluorescent nucleotides with myosin have been compared. The single-molecule studies serve as paradigms for enzyme-catalyzed reactions and ligand-receptor interactions analyzed as individual stochastic processes. Fluorescent nucleotides, called Cy3-EDA-ATP and Cy5-EDA-ATP, were derived by coupling the dyes Cy3.29.OH and Cy5.29.OH (compounds XI and XIV, respectively, in, Bioconjug. Chem. 4:105-111)) with 2'(3')-O-[N-(2-aminoethyl)carbamoyl]ATP (EDA-A...

  9. Fiber size and myosin phenotypes of selected rhesus lower limb muscles after a 14-day spaceflight

    Science.gov (United States)

    Roy, R. R.; Zhong, H.; Bodine, S. C.; Pierotti, D. J.; Talmadge, R. J.; Barkhoudarian, G.; Kim, J.; Fanton, J. W.; Kozlovskaya, I. B.; Edgerton, V. R.

    2000-01-01

    Muscle biopsies were taken from the rhesus (Macaca mulatta) soleus (Sol, a slow ankle extensor), medial gastrocnemius (MG, a fast ankle extensor), tibialis anterior (TA, a fast ankle flexor), and vastus lateralis (VL, a fast knee extensor) muscles in vivarium controls (n=5) before and after either a 14-day spaceflight (Bion 11, n=2) or a 14-day ground-based flight simulation (n=3). Myosin heavy chain (MHC) composition (gel electrophoresis), fiber type distribution (immunohistochemistry), and fiber size were determined. Although there were no significant changes, each muscle showed trends towards adaptation.

  10. Protocol for high-resolution electrophoresis separation of myosin heavy chain isoforms in bovine skeletal muscle.

    Science.gov (United States)

    Picard, Brigitte; Barboiron, Christiane; Chadeyron, David; Jurie, Catherine

    2011-07-01

    In this short communication we describe a specific protocol for SDS-PAGE separation of adult bovine myosin heavy-chain (MyHC) isoforms. The conditions defined in this protocol allow a good separation with a good reproducibility of the four MyHC isoforms (MyHC I, IIa, IIx, IIb) identified in adult skeletal muscle of this species. This procedure uses mini-gel electrophoresis system and does not involve preparation of gradient separating gels. In addition, this protocol can also be applied to the electrophoretic separation of ovine and camel MyHC isoforms. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The IQ motif drives the nuclear translocation of nuclear myosin I

    Czech Academy of Sciences Publication Activity Database

    Dzijak, Rastislav; Yildirim, Sukriye; Kahle, Michal; Hozák, Pavel

    2008-01-01

    Roč. 275, č. 1 (2008), s. 67-67 E-ISSN 1742-4658. [FEBS Congress /33rd/, IUBMB conference /11th/. 28.06.2008-03.07.2008, Athens] R&D Projects: GA MŠk LC545; GA ČR(CZ) GA204/07/1592 Grant - others:GAČR(CZ) GD204/05/H023 Program:GD Institutional research plan: CEZ:AV0Z50520514 Keywords : nuclear myosin * nuclear transport Subject RIV: EB - Genetics ; Molecular Biology

  12. Genes influenced by the non-muscle isoform of Myosin light chain kinase impact human cancer prognosis.

    Directory of Open Access Journals (Sweden)

    Tong Zhou

    Full Text Available The multifunctional non-muscle isoform of myosin light chain kinase (nmMLCK is critical to the rapid dynamic coordination of the cytoskeleton involved in cancer cell proliferation and migration. We identified 45 nmMLCK-influenced genes by bioinformatic filtering of genome-wide expression in wild type and nmMLCK knockout (KO mice exposed to preclinical models of murine acute inflammatory lung injury, pathologies that are well established to include nmMLCK as an essential participant. To determine whether these nmMLCK-influenced genes were relevant to human cancers, the 45 mouse genes were matched to 38 distinct human orthologs (M38 signature (GeneCards definition and underwent Kaplan-Meier survival analysis in training and validation cohorts. These studies revealed that in training cohorts, the M38 signature successfully identified cancer patients with poor overall survival in breast cancer (P<0.001, colon cancer (P<0.001, glioma (P<0.001, and lung cancer (P<0.001. In validation cohorts, the M38 signature demonstrated significantly reduced overall survival for high-score patients of breast cancer (P = 0.002, colon cancer (P = 0.035, glioma (P = 0.023, and lung cancer (P = 0.023. The association between M38 risk score and overall survival was confirmed by univariate Cox proportional hazard analysis of overall survival in the both training and validation cohorts. This study, providing a novel prognostic cancer gene signature derived from a murine model of nmMLCK-associated lung inflammation, strongly supports nmMLCK-involved pathways in tumor growth and progression in human cancers and nmMLCK as an attractive candidate molecular target in both inflammatory and neoplastic processes.

  13. Strong-coupling approximations

    International Nuclear Information System (INIS)

    Abbott, R.B.

    1984-03-01

    Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures

  14. Strong interaction and QFD

    International Nuclear Information System (INIS)

    Ebata, T.

    1981-01-01

    With an assumed weak multiplet structure for bosonic hadrons, which is consistent with the ΔI = 1/2 rule, it is shown that the strong interaction effective hamiltonian is compatible with the weak SU(2) x U(1) gauge transformation. Especially the rho-meson transforms as a triplet under SU(2)sub(w), and this is the origin of the rho-photon analogy. It is also shown that the existence of the non-vanishing Cabibbo angle is a necessary condition for the absence of the exotic hadrons. (orig.)

  15. Head-neck domain of Arabidopsis myosin XI, MYA2, fused with GFP produces F-actin patterns that coincide with fast organelle streaming in different plant cells

    Directory of Open Access Journals (Sweden)

    Holweg Carola L

    2008-07-01

    Full Text Available Abstract Background The cytoskeletal mechanisms that underlie organelle transport in plants are intimately linked to acto-myosin function. This function is mediated by the attachment of myosin heads to F-actin and the binding of cargo to the tails. Acto-myosin also powers vigorous cytoplasmic streaming in plant cells. Class XI myosins exhibit strikingly fast velocities and may have extraordinary roles in cellular motility. Studies of the structural basis of organelle transport have focused on the cargo-binding tails of myosin XI, revealing a close relationship with the transport of peroxisomes, mitochondria, and Golgi-vesicles. Links between myosin heads and F-actin-based motility have been less investigated. To address this function, we performed localization studies using the head-neck domain of AtMYA2, a myosin XI from Arabidopsis. Results We expressed the GFP-fused head-neck domain of MYA2 in epidermal cells of various plant species and found that it associated with F-actin. By comparison to other markers such as fimbrin and talin, we revealed that the myosin-labeled F-actin was of a lower quality and absent from the fine microfilament arrays at the cell cortex. However, it colocalized with cytoplasmic (transvacuolar F-actin in areas coinciding with the tracks of fast organelles. This observation correlates well with the proposed function of myosin XI in organelle trafficking. The fact that organelle streaming was reduced in cells expressing the GFP-MYA2-head6IQ indicated that the functionless motor protein inhibits endogenous myosins. Furthermore, co-expression of the GFP-MYA2-head6IQ with other F-actin markers disrupted its attachment to F-actin. In nuclei, the GFP-myosin associated with short bundles of F-actin. Conclusion The localization of the head of MYA2 in living plant cells, as investigated here for the first time, suggests a close linkage between this myosin XI and cytoplasmic microfilaments that support the rapid streaming of

  16. Botulinum Toxin Type A Inhibits α-Smooth Muscle Actin and Myosin II Expression in Fibroblasts Derived From Scar Contracture.

    Science.gov (United States)

    Chen, Minliang; Yan, Tongtong; Ma, Kui; Lai, Linying; Liu, Chang; Liang, Liming; Fu, Xiaobing

    2016-09-01

    Scar contracture (SC) is one of the most common complications resulting from major burn injuries. Numerous treatments are currently available but they do not always yield excellent therapeutic results. Recent reports suggest that botulinum toxin type A (BTXA) is effective at reducing SC clinically, but the molecular mechanism for this action is unknown. α-Smooth muscle actin (α-SMA) and myosin II are the main components of stress fibers, which are the contractile structures of fibroblasts. The effects of BTXA on α-SMA and myosin II in SC are still unknown. This study aimed to explore the effect of BTXA on α-SMA and myosin II expression in fibroblasts derived from SC and to elucidate its actual mechanism further. Fibroblasts were isolated from tissue specimens of SC. Fibroblasts were cultured in Dulbecco modified Eagle medium with different concentrations of BTXA and their proliferation was analyzed through the tetrazolium-based colorimetric method at 1, 4, and 7 days. Proteins of α-SMA and myosin II were checked using Western blot in fibroblasts treated with different concentrations of BTXA at 1, 4, and 7 days. Fibroblasts without BTXA treatment had a higher proliferation than that in other groups, which indicated that the proliferation of fibroblasts was significantly inhibited by BTXA (P < 0.05). Proteins of α-SMA and myosin II between fibroblasts with BTXA and fibroblasts without BTXA are statistically significant (P < 0.05). These results suggest that BTXA effectively inhibited the growth of fibroblasts derived from SC and reduced the expression of α-SMA and myosin II, which provided theoretical support for the application of BTXA to control SC.

  17. Myosin Va Plays a Role in Nitrergic Smooth Muscle Relaxation in Gastric Fundus and Corpora Cavernosa of Penis

    Science.gov (United States)

    Carew, Josephine A.; Goyal, Raj K.; Sullivan, Maryrose P.

    2014-01-01

    The intracellular motor protein myosin Va is involved in nitrergic neurotransmission possibly by trafficking of neuronal nitric oxide synthase (nNOS) within the nerve terminals. In this study, we examined the role of myosin Va in the stomach and penis, proto-typical smooth muscle organs in which nitric oxide (NO) mediated relaxation is critical for function. We used confocal microscopy and co-immunoprecipitation of tissue from the gastric fundus (GF) and penile corpus cavernosum (CCP) to localize myosin Va with nNOS and demonstrate their molecular interaction. We utilized in vitro mechanical studies to test whether smooth muscle relaxations during nitrergic neuromuscular neurotransmission is altered in DBA (dilute, brown, non-agouti) mice which lack functional myosin Va. Myosin Va was localized in nNOS-positive nerve terminals and was co-immunoprecipitated with nNOS in both GF and CCP. In comparison to C57BL/6J wild type (WT) mice, electrical field stimulation (EFS) of precontracted smooth muscles of GF and CCP from DBA animals showed significant impairment of nitrergic relaxation. An NO donor, Sodium nitroprusside (SNP), caused comparable levels of relaxation in smooth muscles of WT and DBA mice. These normal postjunctional responses to SNP in DBA tissues suggest that impairment of smooth muscle relaxation resulted from inhibition of NO synthesis in prejunctional nerve terminals. Our results suggest that normal physiological processes of relaxation of gastric and cavernosal smooth muscles that facilitate food accommodation and penile erection, respectively, may be disrupted under conditions of myosin Va deficiency, resulting in complications like gastroparesis and erectile dysfunction. PMID:24516539

  18. Bound anionic states of adenine

    Energy Technology Data Exchange (ETDEWEB)

    Haranczyk, Maciej; Gutowski, Maciej S; Li, Xiang; Bowen, Kit H

    2007-03-20

    Anionic states of nucleic acid bases are involved in DNA damage by low-energy electrons and in charge transfer through DNA. Previous gas phase studies of free, unsolvated nucleic acid base parent anions probed only dipole-bound states, which are not present in condensed phase environments, but did not observe valence anionic states, which for purine bases, are thought to be adiabatically unbound. Contrary to this expectation, we have demonstrated that some thus far ignored tautomers of adenine, which result from enamine-imine transformations, support valence anionic states with electron vertical detachment energies as large as 2.2 eV, and at least one of these anionic tautomers is adiabatically bound. Moreover, we predict that the new anionic tautomers should also dominate in solutions and should be characterized by larger values of electron vertical detachment energy than the canonical valence anion. All of the new-found anionic tautomers might be formed in the course of dissociative electron attachment followed by a hydrogen atom attachment to a carbon atom, and they might affect the structure and properties of DNA and RNA exposed to low-energy electrons. The discovery of these valence anionic states of adenine was facilitated by the development of: (i) a new experimental method for preparing parent anions of nucleic acid bases for photoelectron experiments, and (ii) a new combinatorial/ quantum chemical approach for identification of the most stable tautomers of organic molecules. The computational portion of this work was supported by the: (i) Polish State Committee for Scientific Research (KBN) Grants: DS/8000-4-0140-7 (M.G.) and N204 127 31/2963 (M.H.), (ii) European Social Funds (EFS) ZPORR/2.22/II/2.6/ARP/U/2/05 (M.H.), and (iii) US DOE Office of Biological and Environmental Research, Low Dose Radiation Research Program (M.G.). M.H. holds the Foundation for Polish Science (FNP) award for young scientists. The calculations were performed at the Academic

  19. Instanton bound states in ABJM theory

    Energy Technology Data Exchange (ETDEWEB)

    Hatsuda, Yasuyuki [DESY Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst. and Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics

    2013-06-15

    The partition function of the ABJM theory receives non-perturbative corrections due to instanton effects. We study these non-perturbative corrections, including bound states of worldsheet instantons and membrane instantons, in the Fermi-gas approach. We require that the total non-perturbative correction should be always finite for arbitrary Chern-Simons level. This finiteness is realized quite non-trivially because each bound state contribution naively diverges at some levels. The poles of each contribution should be canceled out in total. We use this pole cancellation mechanism to find unknown bound state corrections from known ones. We conjecture a general expression of the bound state contribution. Summing up all the bound state contributions, we find that the effect of bound states is simply incorporated into the worldsheet instanton correction by a redefinition of the chemical potential in the Fermi-gas system. Analytic expressions of the 3- and 4-membrane instanton corrections are also proposed.

  20. Physics with loosely bound nuclei

    Indian Academy of Sciences (India)

    Abstract. The essential aspect of contemporary physics is to understand properties of nucleonic matter that constitutes the world around us. Over the years research in nuclear physics has provided strong guidance in understanding the basic principles of nuclear interactions. But, the scenario of nuclear physics changed ...

  1. Physics with loosely bound nuclei

    Indian Academy of Sciences (India)

    The essential aspect of contemporary physics is to understand properties of nucleonic matter that constitutes the world around us. Over the years research in nuclear physics has provided strong guidance in understanding the basic principles of nuclear interactions. But, the scenario of nuclear physics changed drastically as ...

  2. Strong Coupling Holography

    CERN Document Server

    Dvali, Gia

    2009-01-01

    We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...

  3. Photochemistry of triarylmethane dyes bound to proteins

    Science.gov (United States)

    Indig, Guilherme L.

    1996-04-01

    Triarylmethanes represent a class of cationic dyes whose potential as photosensitizers for use in photodynamic therapy of neoplastic diseases has never been comprehensively evaluated. Here, the laser-induced photodecomposition of three triarylmethane dyes, crystal violet, ethyl violet, and malachite green, non-covalently bound to bovine serum albumin (a model biological target) was investigated. Upon laser excitation at 532 nm, the bleaching of the corresponding dye-protein molecular complexes follows spectroscopic patterns that suggest the formation of reduced forms of the dyes as major reaction photoproducts. That implies that an electron or hydrogen atom transfer from the protein to the dye's moiety within the guest-host complex is the first step of the photobleaching process. Since the availability of dissolved molecular oxygen was not identified as a limiting factor for the phototransformations to occur, these dyes can be seen as potential phototherapeutic agents for use in hypoxic areas of tumors. These triarylmethane dyes strongly absorb at relatively long wavelengths (absorption maximum around 600 nm; (epsilon) max approximately equals 105 M-1 cm-1), and only minor changes in their absorption characteristics are observed upon binding to the protein. However the binding event leads to a remarkable increase in their fluorescence quantum yield and photoreactivity.

  4. Surfactant-bound monolithic columns for CEC.

    Science.gov (United States)

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Shamsi, Shahab A

    2009-11-01

    A novel anionic surfactant bound monolithic stationary phase based on 11-acrylaminoundecanoic acid is designed for CEC. The monolith possessing bonded undecanoyl groups (hydrophobic sites) and carboxyl groups (weak cationic ion-exchange sites) were evaluated as a mixed-mode stationary phase in CEC for the separation of neutral and polar solutes. Using a multivariate D-optimal design the composition of the polymerization mixture was modeled and optimized with five alkylbenzenes and seven alkyl phenyl ketones as test solutes. The D-optimal design indicates a strong dependence of electrochromatographic parameters on the concentration of 11-acrylaminoundecanoic acid monomer and porogen (water) in the polymerization mixture. A difference of 6, 8 and 13% RSD between the predicted and the experimental values in terms of efficiency, resolution and retention time, respectively, indeed confirmed that the proposed approach is practical. The physical (i.e. morphology, porosity and permeability) and chromatographic properties of the monolithic columns were thoroughly investigated. With the optimized monolithic column, high efficiency separation of N-methylcarbamates pesticides and positional isomers was successfully achieved. It appears that this type of mixed-mode monolith (containing both chargeable and hydrophobic sites) may have a great potential as a new generation of CEC stationary phase.

  5. Rhodium catalysts bound to functionalized mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Bitterwolf, Thomas E.; Newell, J D.; Carver, Colin T.; Addleman, Raymond S.; Linehan, John C.; Fryxell, Glen E.

    2004-07-20

    Phosphine and amine functionalized mesoporous silica materials were metallated with Rh(CO)2(i-Pr2NH)Cl or Rh2(CO)4Cl2, respectively, to yield catalysts containing the Rh(PPh2R)2(CO)Cl or Rh(CO)2(NH2R)Cl, where R is a propyl chain bonded to the silica surface, reactive centers. In order to ascertain the effect of pore size on rates of hydroformylation catalysis both 35 and 45 ? pore size materials were used. Using the hydroformylation of octene as a reference reaction, the phosphine based, 45 ? catalysts were 1.5-1.3 times faster than the amine based, 45 ? materials were 2.6-2.1 times faster than the 35 ? catalysts, and the 45 ? materials. The orientation of the catalyst relative to the functionalized surface, and the steric environment around the catalyst active site appear to be significant in determining rate of reaction. The ability of the surface bound phosphine catalysts to affect hydroformylation was strongly influenced by the steric constraints of the substrate. Terminal alkenes were readily hydroformylated and norbornene was slowly hydroformylated, but pinene, trans-cyclododecene, cyclohexene and cholesterol were nonreactive to the catalytic center.

  6. Bounding the Higgs boson width through interferometry.

    Science.gov (United States)

    Dixon, Lance J; Li, Ye

    2013-09-13

    We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum.

  7. Unfolding transitions in myosin give rise to the double-hyperbolic force-velocity relation in muscle

    DEFF Research Database (Denmark)

    Nielsen, Bjørn Gilbert

    2003-01-01

    This work presents an extension to a recent model of muscle contraction that was based on entropic elasticity (Nielsen 2002 J. Theor Biol. 219 99-119). By using entropic elasticity as the origin of muscle force, various possibilities emerge that can account for the presence of the double-hyperbol...... in the entropic spring array from being mainly composed of non-unfolded myosin springs that have a short (i.e. normal) contour length to consisting of a mixture of myosin springs with short and long (unfolded) contour lengths....

  8. Stabilization of the Central Part of Tropomyosin Molecule Alters the Ca2+-sensitivity of Actin-Myosin Interaction

    OpenAIRE

    Shchepkin, D.V.; Matyushenko, A. M.; Kopylova, G. V.; Artemova, N. V.; Bershitsky, S. Y.; Tsaturyan, A. K.; Levitsky, D. I.

    2013-01-01

    We show that the mutations D137L and G126R, which stabilize the central part of the tropomyosin (Tm) molecule, increase both the maximal sliding velocity of the regulated actin filaments in the in vitro motility assay at high Са 2+ concentrations and the Са 2+-sensitivity of the actin-myosin interaction underlying this sliding. Based on an analysis of the recently published data on the structure of the actin–Tm–myosin complex, we suppose that the physiological effects of these mutations in Tm...

  9. Bounded elements in Locally C*-algebras

    International Nuclear Information System (INIS)

    El Harti, Rachid

    2001-09-01

    In order to get more useful information about Locally C*-algebras, we introduce in this paper the notion of bounded elements. First, we study the connection between bounded elements and spectrally bounded elements. Some structural results of Locally C*-algebras are established in Theorems 1 , 2 and 3. As an immediate consequence of Theorem 3, we give a characterization of the connected component of the identity in the group of unitary elements for a Locally C*-algebra. (author)

  10. Boundedly UC spaces: characterisations and preservation | Jain ...

    African Journals Online (AJOL)

    A metric space (X, d) is called a boundedly UC space if every closed and bounded subset of X is a UC space. A metric space (X, d) is called a UC space if each real-valued continuous function on (X, d) is uniformly continuous. In this paper, we study twenty-two equivalent conditions for a metric space to be a boundedly UC ...

  11. Strong interaction studies with kaonic atoms

    Directory of Open Access Journals (Sweden)

    Marton J.

    2016-01-01

    Full Text Available The strong interaction of antikaons (K− with nucleons and nuclei in the low-energy regime represents an active research field connected intrinsically with few-body physics. There are important open questions like the question of antikaon nuclear bound states - the prototype system being K−pp. A unique and rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions in low-lying states of light kaonic atoms like kaonic hydrogen isotopes. In the SIDDHARTA experiment at the electron-positron collider DAΦNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound K−p atom leading to a hadronic shift ϵ1s and a hadronic broadening Γ1s of the 1s state. The SIDDHARTA result triggered new theoretical work which achieved major progress in the understanding of the low-energy strong interaction with strangeness. Antikaon-nucleon scattering lengths have been calculated constrained by the SIDDHARTA data on kaonic hydrogen. For the extraction of the isospin-dependent scattering lengths a measurement of the hadronic shift and width of kaonic deuterium is necessary. Therefore, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2. Many improvements in the experimental setup will allow to measure kaonic deuterium which is challenging due to the anticipated low X-ray yield. Especially important are the data on the X-ray yields of kaonic deuterium extracted from a exploratory experiment within SIDDHARTA.

  12. Bounded cohomology of discrete groups

    CERN Document Server

    Frigerio, Roberto

    2017-01-01

    The author manages a near perfect equilibrium between necessary technicalities (always well motivated) and geometric intuition, leading the readers from the first simple definition to the most striking applications of the theory in 13 very pleasant chapters. This book can serve as an ideal textbook for a graduate topics course on the subject and become the much-needed standard reference on Gromov's beautiful theory. -Michelle Bucher The theory of bounded cohomology, introduced by Gromov in the late 1980s, has had powerful applications in geometric group theory and the geometry and topology of manifolds, and has been the topic of active research continuing to this day. This monograph provides a unified, self-contained introduction to the theory and its applications, making it accessible to a student who has completed a first course in algebraic topology and manifold theory. The book can be used as a source for research projects for master's students, as a thorough introduction to the field for graduate student...

  13. Strong density of a class of simple operators

    International Nuclear Information System (INIS)

    Somasundaram, S.; Mohammad, N.

    1991-08-01

    An algebra of simple operators has been shown to be strongly dense in the algebra of all bounded linear operators on function spaces of a compact (not necessarily abelian) group. Further, it is proved that the same result is also true for L 2 (G) if G is a locally compact (not necessarily compact) abelian group. (author). 6 refs

  14. Some Improved Nonperturbative Bounds for Fermionic Expansions

    Energy Technology Data Exchange (ETDEWEB)

    Lohmann, Martin, E-mail: marlohmann@gmail.com [Universita di Roma Tre, Dipartimento di Matematica (Italy)

    2016-06-15

    We reconsider the Gram-Hadamard bound as it is used in constructive quantum field theory and many body physics to prove convergence of Fermionic perturbative expansions. Our approach uses a recursion for the amplitudes of the expansion, discovered in a model problem by Djokic (2013). It explains the standard way to bound the expansion from a new point of view, and for some of the amplitudes provides new bounds, which avoid the use of Fourier transform, and are therefore superior to the standard bounds for models like the cold interacting Fermi gas.

  15. Vulnerable Derivatives and Good Deal Bounds

    DEFF Research Database (Denmark)

    Murgoci, Agatha

    2013-01-01

    a new restriction in the arbitrage free model by setting upper bounds on the Sharpe ratios (SRs) of the assets. The potential prices that are eliminated represent unreasonably good deals. The constraint on the SR translates into a constraint on the stochastic discount factor. Thus, tight pricing bounds......We price vulnerable derivatives – i.e. derivatives where the counterparty may default. These are basically the derivatives traded on the over-the-counter (OTC) markets. Default is modelled in a structural framework. The technique employed for pricing is good deal bounds (GDBs). The method imposes...... in a consistent way. Finally, we numerically analyse the behaviour of the good deal pricing bounds....

  16. Modifications of the Bekenstein Bound from Dimensional Reduction of Covariant Entropy Bound

    Science.gov (United States)

    Yee, Ho-Ung

    2005-12-01

    We consider dimensional reduction of the covariant entropy bound from D + 1 dimensional geometry of M × S1 to the D dimensional geometry M. With a warping factor, the local Bekenstein bound in D + 1 dimensions leads to a more refined form of the local Bekenstein bound from the D dimensional view point. With this new local Bekenstein bound, it is possible to saturate the lightlike holography bound even with nonvanishing expansion rate. With a Kaluza-Klein gauge field, the dimensional reduction implies a stronger bound where the energy momentum tensor contribution is replaced by the energy momentum tensor with the electromagnetic contribution subtracted.

  17. LIGO: The strong belief

    CERN Multimedia

    Antonella Del Rosso

    2016-01-01

    Twenty years of designing, building and testing a number of innovative technologies, with the strong belief that the endeavour would lead to a historic breakthrough. The Bulletin publishes an abstract of the Courier’s interview with Barry Barish, one of the founding fathers of LIGO.   The plots show the signals of gravitational waves detected by the twin LIGO observatories at Livingston, Louisiana, and Hanford, Washington. (Image: Caltech/MIT/LIGO Lab) On 11 February, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations published a historic paper in which they showed a gravitational signal emitted by the merger of two black holes. These results come after 20 years of hard work by a large collaboration of scientists operating the two LIGO observatories in the US. Barry Barish, Linde Professor of Physics, Emeritus at the California Institute of Technology and former Director of the Global Design Effort for the Internat...

  18. Myosin-independent cytokinesis inGiardiautilizes flagella to coordinate force generation and direct membrane trafficking.

    Science.gov (United States)

    Hardin, William R; Li, Renyu; Xu, Jason; Shelton, Andrew M; Alas, Germain C M; Minin, Vladimir N; Paredez, Alexander R

    2017-07-18

    Devoid of all known canonical actin-binding proteins, the prevalent parasite Giardia lamblia uses an alternative mechanism for cytokinesis. Unique aspects of this mechanism can potentially be leveraged for therapeutic development. Here, live-cell imaging methods were developed for Giardia to establish division kinetics and the core division machinery. Surprisingly, Giardia cytokinesis occurred with a median time that is ∼60 times faster than mammalian cells. In contrast to cells that use a contractile ring, actin was not concentrated in the furrow and was not directly required for furrow progression. Live-cell imaging and morpholino depletion of axonemal Paralyzed Flagella 16 indicated that flagella-based forces initiated daughter cell separation and provided a source for membrane tension. Inhibition of membrane partitioning blocked furrow progression, indicating a requirement for membrane trafficking to support furrow advancement. Rab11 was found to load onto the intracytoplasmic axonemes late in mitosis and to accumulate near the ends of nascent axonemes. These developing axonemes were positioned to coordinate trafficking into the furrow and mark the center of the cell in lieu of a midbody/phragmoplast. We show that flagella motility, Rab11, and actin coordination are necessary for proper abscission. Organisms representing three of the five eukaryotic supergroups lack myosin II of the actomyosin contractile ring. These results support an emerging view that flagella play a central role in cell division among protists that lack myosin II and additionally implicate the broad use of membrane tension as a mechanism to drive abscission.

  19. Inactivation, subunit dissociation, aggregation, and unfolding of myosin subfragment 1 during guanidine denaturation.

    Science.gov (United States)

    Nozais, M; Béchet, J J; Houadjeto, M

    1992-02-04

    The effect of guanidine hydrochloride on ATPase activity, gel filtration, turbidity, exposure of thiol groups, far-UV circular dichroism, and the fluorescence emission intensity of myosin subfragment 1 (S-1) was studied under equilibrium conditions. It was found that the denaturation process involves several intermediate states. The enzymatic activity of S-1 is at first lost at very low concentrations of GdnHCl (lower than 0.5 M). At a slightly higher GdnHCl concentration (about 0.5 M), the light chains dissociate and this dissociation is closely followed by the formation of aggregates between the naked heavy chains of S-1 molecules in the guanidine hydrochloride range of concentrations 0.5-1 M. At GdnHCl concentrations above 1 M, aggregates gradually disappear and S-1 loses its secondary and tertiary structures. These phenomena are partly reversible, and ATPase activity is only partially recovered under highly limited conditions. These results are discussed in relation to the nature of myosin subunit assembly. The head fragment of 20 kDa is thus suggested to be implicated in the binding of light chain to heavy chain and in the self-association of free heavy chains.

  20. Recombinant motor domain constructs of Chara corallina myosin display fast motility and high ATPase activity.

    Science.gov (United States)

    Ito, Kohji; Kashiyama, Taku; Shimada, Kiyo; Yamaguchi, Akira; Awata, Jun ya; Hachikubo, You; Manstein, Dietmar J; Yamamoto, Keiichi

    2003-12-26

    The mechanism and structural features that are responsible for the fast motility of Chara corallina myosin (CCM) have not been elucidated, so far. The low yields of native CCM that can be purified to homogeneity were the major reason for this. Here, we describe the expression of recombinant CCM motor domains, which support the fast movement of actin filaments in an in vitro motility assay. A CCM motor domain without light chain binding site moved actin filaments at a velocity of 8.8 microm/s at 30 degrees C and a CCM motor domain with an artificial lever arm consisting of two alpha-actinin repeats moved actin filaments at 16.2 microm/s. Both constructs displayed high actin-activated ATPase activities ( approximately 500 Pi/s/head), which is indicative of a very fast hydrolysis step. Our results provide an excellent system to dissect the specific structural and functional features that distinguish the myosin responsible for fast cytoplasmic streaming.

  1. The role of myosin II in glioma invasion: A mathematical model.

    Directory of Open Access Journals (Sweden)

    Wanho Lee

    Full Text Available Gliomas are malignant tumors that are commonly observed in primary brain cancer. Glioma cells migrate through a dense network of normal cells in microenvironment and spread long distances within brain. In this paper we present a two-dimensional multiscale model in which a glioma cell is surrounded by normal cells and its migration is controlled by cell-mechanical components in the microenvironment via the regulation of myosin II in response to chemoattractants. Our simulation results show that the myosin II plays a key role in the deformation of the cell nucleus as the glioma cell passes through the narrow intercellular space smaller than its nuclear diameter. We also demonstrate that the coordination of biochemical and mechanical components within the cell enables a glioma cell to take the mode of amoeboid migration. This study sheds lights on the understanding of glioma infiltration through the narrow intercellular spaces and may provide a potential approach for the development of anti-invasion strategies via the injection of chemoattractants for localization.

  2. Lampreys have a single gene cluster for the fast skeletal myosin heavy chain gene family.

    Directory of Open Access Journals (Sweden)

    Daisuke Ikeda

    Full Text Available Muscle tissues contain the most classic sarcomeric myosin, called myosin II, which consists of 2 heavy chains (MYHs and 4 light chains. In the case of humans (tetrapod, a total of 6 fast skeletal-type MYH genes (MYHs are clustered on a single chromosome. In contrast, torafugu (teleost contains at least 13 fast skeletal MYHs, which are distributed in 5 genomic regions; the MYHs are clustered in 3 of these regions. In the present study, the evolutionary relationship among fast skeletal MYHs is elucidated by comparing the MYHs of teleosts and tetrapods with those of cyclostome lampreys, one of two groups of extant jawless vertebrates (agnathans. We found that lampreys contain at least 3 fast skeletal MYHs, which are clustered in a head-to-tail manner in a single genomic region. Although there was apparent synteny in the corresponding MYH cluster regions between lampreys and tetrapods, phylogenetic analysis indicated that lamprey and tetrapod MYHs have independently duplicated and diversified. Subsequent transgenic approaches showed that the 5'-flanking sequences of Japanese lamprey fast skeletal MYHs function as a regulatory sequence to drive specific reporter gene expression in the fast skeletal muscle of zebrafish embryos. Although zebrafish MYH promoters showed apparent activity to direct reporter gene expression in myogenic cells derived from mice, promoters from Japanese lamprey MYHs had no activity. These results suggest that the muscle-specific regulatory mechanisms are partially conserved between teleosts and tetrapods but not between cyclostomes and tetrapods, despite the conserved synteny.

  3. Nonmuscle Myosin II Regulates the Morphogenesis of Metanephric Mesenchyme-Derived Immature Nephrons.

    Science.gov (United States)

    Recuenco, Mariam C; Ohmori, Tomoko; Tanigawa, Shunsuke; Taguchi, Atsuhiro; Fujimura, Sayoko; Conti, Mary Anne; Wei, Qize; Kiyonari, Hiroshi; Abe, Takaya; Adelstein, Robert S; Nishinakamura, Ryuichi

    2015-05-01

    The kidney develops from reciprocal interactions between the metanephric mesenchyme and ureteric bud. The mesenchyme transforms into epithelia and forms complicated nephron structures, whereas the ureteric bud extends its pre-existing epithelial ducts. Although the roles are well established for extracellular stimuli, such as Wnt and Notch, it is unclear how the intracellular cytoskeleton regulates these morphogenetic processes. Myh9 and Myh10 encode nonmuscle myosin II heavy chains, and Myh9 mutations in humans are implicated in congenital kidney diseases and focal segmental glomerulosclerosis in adults. Here, we analyzed the roles of Myh9 and Myh10 in the developing kidney. Ureteric bud-specific depletion of Myh9 resulted in no apparent phenotypes, whereas mesenchyme-specific Myh9 deletion caused proximal tubule dilations and renal failure. Mesenchyme-specific Myh9/Myh10 mutant mice died shortly after birth and showed a severe defect in nephron formation. The nascent mutant nephrons failed to form a continuous lumen, which likely resulted from impaired apical constriction of the elongating tubules. In addition, nephron progenitors lacking Myh9/Myh10 or the possible interactor Kif26b were less condensed at midgestation and reduced at birth. Taken together, nonmuscle myosin II regulates the morphogenesis of immature nephrons derived from the metanephric mesenchyme and the maintenance of nephron progenitors. Our data also suggest that Myh9 deletion in mice results in failure to maintain renal tubules but not in glomerulosclerosis. Copyright © 2015 by the American Society of Nephrology.

  4. Coupling of two non-processive myosin 5c dimers enables processive stepping along actin filaments.

    Science.gov (United States)

    Gunther, Laura K; Furuta, Ken'ya; Bao, Jianjun; Urbanowski, Monica K; Kojima, Hiroaki; White, Howard D; Sakamoto, Takeshi

    2014-05-09

    Myosin 5c (Myo5c) is a low duty ratio, non-processive motor unable to move continuously along actin filaments though it is believed to participate in secretory vesicle trafficking in vertebrate cells. Here, we measured the ATPase kinetics of Myo5c dimers and tested the possibility that the coupling of two Myo5c molecules enables processive movement. Steady-state ATPase activity and ADP dissociation kinetics demonstrated that a dimer of Myo5c-HMM (double-headed heavy meromyosin 5c) has a 6-fold lower Km for actin filaments than Myo5c-S1 (single-headed myosin 5c subfragment-1), indicating that the two heads of Myo5c-HMM increase F-actin-binding affinity. Nanometer-precision tracking analyses showed that two Myo5c-HMM dimers linked with each other via a DNA scaffold and moved processively along actin filaments. Moreover, the distance between the Myo5c molecules on the DNA scaffold is an important factor for the processive movement. Individual Myo5c molecules in two-dimer complexes move stochastically in 30-36 nm steps. These results demonstrate that two dimers of Myo5c molecules on a DNA scaffold increased the probability of rebinding to F-actin and enabled processive steps along actin filaments, which could be used for collective cargo transport in cells.

  5. Myosin head orientation: a structural determinant for the Frank-Starling relationship

    Energy Technology Data Exchange (ETDEWEB)

    Farman, Gerrie P.; Gore, David; Allen, Edward; Schoenfelt, Kelly; Irving, Thomas C.; de Tombe, Pieter P. (IIT); (UIC)

    2011-09-06

    The cellular mechanism underlying the Frank-Starling law of the heart is myofilament length-dependent activation. The mechanism(s) whereby sarcomeres detect changes in length and translate this into increased sensitivity to activating calcium has been elusive. Small-angle X-ray diffraction studies have revealed that the intact myofilament lattice undergoes numerous structural changes upon an increase in sarcomere length (SL): lattice spacing and the I{sub 1,1}/I{sub 1,0} intensity ratio decreases, whereas the M3 meridional reflection intensity (I{sub M3}) increases, concomitant with increases in diastolic and systolic force. Using a short ({approx}10 ms) X-ray exposure just before electrical stimulation, we were able to obtain detailed structural information regarding the effects of external osmotic compression (with mannitol) and obtain SL on thin intact electrically stimulated isolated rat right ventricular trabeculae. We show that over the same incremental increases in SL, the relative changes in systolic force track more closely to the relative changes in myosin head orientation (as reported by IM3) than to the relative changes in lattice spacing. We conclude that myosin head orientation before activation determines myocardial sarcomere activation levels and that this may be the dominant mechanism for length-dependent activation.

  6. Muscle Lim Protein and myosin binding protein C form a complex regulating muscle differentiation.

    Science.gov (United States)

    Arvanitis, Demetrios A; Vafiadaki, Elizabeth; Papalouka, Vasiliki; Sanoudou, Despina

    2017-12-01

    Muscle Lim Protein (MLP) is a protein with multiple functional roles in striated muscle physiology and pathophysiology. Herein, we demonstrate that MLP directly binds to slow, fast, and cardiac myosin-binding protein C (MyBP-C) during myogenesis, as shown by yeast two-hybrid and a range of protein-protein interaction assays. The minimal interacting domains involve MLP inter-LIM and MyBP-C [C4]. The interaction is sensitive to cytosolic Ca 2+ concentrations changes and to MyBP-C phosphorylation by PKA or CaMKII. Confocal microscopy of differentiating myoblasts showed MLP and MyBP-C colocalization during myoblast differentiation. Suppression of the complex formation with recombinant MyBP-C [C4] peptide overexpression, inhibited myoblast differentiation by 65%. Suppression of both MLP and MyBP-C expression in myoblasts by siRNA revealed negative synergistic effects on differentiation. The MLP/MyBP-C complex modulates the actin activated myosin II ATPase activity in vitro, which could interfere with sarcomerogenesis and myofilaments assembly during differentiation. Our data demonstrate a critical role of the MLP/MyBP-C complex during early myoblast differentiation. Its absence in muscles with mutations or aberrant expression of MLP or MyBP-C could be directly implicated in the development of cardiac and skeletal myopathies. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Improved rigorous upper bounds for transport due to passive advection described by simple models of bounded systems

    International Nuclear Information System (INIS)

    Kim, Chang-Bae; Krommes, J.A.

    1988-08-01

    The work of Krommes and Smith on rigorous upper bounds for the turbulent transport of a passively advected scalar [/ital Ann. Phys./ 177:246 (1987)] is extended in two directions: (1) For their ''reference model,'' improved upper bounds are obtained by utilizing more sophisticated two-time constraints which include the effects of cross-correlations up to fourth order. Numerical solutions of the model stochastic differential equation are also obtained; they show that the new bounds compare quite favorably with the exact results, even at large Reynolds and Kubo numbers. (2) The theory is extended to take account of a finite spatial autocorrelation length L/sub c/. As a reasonably generic example, the problem of particle transport due to statistically specified stochastic magnetic fields in a collisionless turbulent plasma is revisited. A bound is obtained which reduces for small L/sub c/ to the quasilinear limit and for large L/sub c/ to the strong turbulence limit, and which provides a reasonable and rigorous interpolation for intermediate values of L/sub c/. 18 refs., 6 figs

  8. Head-head interactions of resting myosin crossbridges in intact frog skeletal muscles, revealed by synchrotron x-ray fiber diffraction.

    Directory of Open Access Journals (Sweden)

    Kanji Oshima

    Full Text Available The intensities of the myosin-based layer lines in the x-ray diffraction patterns from live resting frog skeletal muscles with full thick-thin filament overlap from which partial lattice sampling effects had been removed were analyzed to elucidate the configurations of myosin crossbridges around the thick filament backbone to nanometer resolution. The repeat of myosin binding protein C (C-protein molecules on the thick filaments was determined to be 45.33 nm, slightly longer than that of myosin crossbridges. With the inclusion of structural information for C-proteins and a pre-powerstroke head shape, modeling in terms of a mixed population of regular and perturbed regions of myosin crown repeats along the filament revealed that the myosin filament had azimuthal perturbations of crossbridges in addition to axial perturbations in the perturbed region, producing pseudo-six-fold rotational symmetry in the structure projected down the filament axis. Myosin crossbridges had a different organization about the filament axis in each of the regular and perturbed regions. In the regular region that lacks C-proteins, there were inter-molecular interactions between the myosin heads in axially adjacent crown levels. In the perturbed region that contains C-proteins, in addition to inter-molecular interactions between the myosin heads in the closest adjacent crown levels, there were also intra-molecular interactions between the paired heads on the same crown level. Common features of the interactions in both regions were interactions between a portion of the 50-kDa-domain and part of the converter domain of the myosin heads, similar to those found in the phosphorylation-regulated invertebrate myosin. These interactions are primarily electrostatic and the converter domain is responsible for the head-head interactions. Thus multiple head-head interactions of myosin crossbridges also characterize the switched-off state and have an important role in the regulation

  9. John Strong (1941 - 2006)

    CERN Multimedia

    Wickens, F

    Our friend and colleague John Strong was cruelly taken from us by a brain tumour on Monday 31st July, a few days before his 65th birthday John started his career working with a group from Westfield College, under the leadership of Ted Bellamy. He obtained his PhD and spent the early part of his career on experiments at Rutherford Appleton Laboratory (RAL), but after the early 1970s his research was focussed on experiments in CERN. Over the years he made a number of notable contributions to experiments in CERN: The Omega spectrometer adopted a system John had originally developed for experiments at RAL using vidicon cameras to record the sparks in the spark chambers; He contributed to the success of NA1 and NA7, where he became heavily involved in the electronic trigger systems; He was responsible for the second level trigger system for the ALEPH detector and spent five years leading a team that designed and built the system, which ran for twelve years with only minor interventions. Following ALEPH he tur...

  10. Stirring Strongly Coupled Plasma

    CERN Document Server

    Fadafan, Kazem Bitaghsir; Rajagopal, Krishna; Wiedemann, Urs Achim

    2009-01-01

    We determine the energy it takes to move a test quark along a circle of radius L with angular frequency w through the strongly coupled plasma of N=4 supersymmetric Yang-Mills (SYM) theory. We find that for most values of L and w the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=Lw or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime to the radiation-dominated regime. In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and that due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implicati...

  11. Strong-interaction nonuniversality

    International Nuclear Information System (INIS)

    Volkas, R.R.; Foot, R.; He, X.; Joshi, G.C.

    1989-01-01

    The universal QCD color theory is extended to an SU(3) 1 direct product SU(3) 2 direct product SU(3) 3 gauge theory, where quarks of the ith generation transform as triplets under SU(3)/sub i/ and singlets under the other two factors. The usual color group is then identified with the diagonal subgroup, which remains exact after symmetry breaking. The gauge bosons associated with the 16 broken generators then form two massive octets under ordinary color. The interactions between quarks and these heavy gluonlike particles are explicitly nonuniversal and thus an exploration of their physical implications allows us to shed light on the fundamental issue of strong-interaction universality. Nonuniversality and weak flavor mixing are shown to generate heavy-gluon-induced flavor-changing neutral currents. The phenomenology of these processes is studied, as they provide the major experimental constraint on the extended theory. Three symmetry-breaking scenarios are presented. The first has color breaking occurring at the weak scale, while the second and third divorce the two scales. The third model has the interesting feature of radiatively induced off-diagonal Kobayashi-Maskawa matrix elements

  12. Pair condensation and bound states in fermionic systems

    International Nuclear Information System (INIS)

    Sedrakian, Armen; Clark, John W.

    2006-01-01

    We study the finite temperature-density phase diagram of an attractive fermionic system that supports two-body (dimer) and three-body (trimer) bound states in free space. Using interactions characteristic for nuclear systems, we obtain the critical temperature T c2 for the superfluid phase transition and the limiting temperature T c3 for the extinction of trimers. The phase diagram features a Cooper-pair condensate in the high-density, low-temperature domain which, with decreasing density, crosses over to a Bose condensate of strongly bound dimers. The high-temperature, low-density domain is populated by trimers whose binding energy decreases toward the density-temperature domain occupied by the superfluid and vanishes at a critical temperature T c3 >T c2

  13. Isoperimetric upper bounds for the first eigenvalue

    Indian Academy of Sciences (India)

    [5] Buser P and Karcher H, Gromov's almost flat manifolds, Société mathématique de. France (1981). [6] Grosjean J F, Upper bounds for the first eigenvalue of the Laplacian on compact submanifolds, Pacific. J. Math. 206 (2002) 93–112. [7] Heintze Ernst, Extinsic upper bounds for λ1, Math. Ann. 280 (1988) 389–402.

  14. No-arbitrage bounds for financial scenarios

    DEFF Research Database (Denmark)

    Geyer, Alois; Hanke, Michael; Weissensteiner, Alex

    2014-01-01

    We derive no-arbitrage bounds for expected excess returns to generate scenarios used in financial applications. The bounds allow to distinguish three regions: one where arbitrage opportunities will never exist, a second where arbitrage may be present, and a third, where arbitrage opportunities...

  15. On the range of completely bounded maps

    Directory of Open Access Journals (Sweden)

    Richard I. Loebl

    1978-01-01

    Full Text Available It is shown that if every bounded linear map from a C*-algebra α to a von Neumann algebra β is completely bounded, then either α is finite-dimensional or β⫅⊗Mn, where is a commutative von Neumann algebra and Mn is the algebra of n×n complex matrices.

  16. Bound constrained quadratic programming via piecewise

    DEFF Research Database (Denmark)

    Madsen, Kaj; Nielsen, Hans Bruun; Pinar, M. C.

    1999-01-01

    We consider the strictly convex quadratic programming problem with bounded variables. A dual problem is derived using Lagrange duality. The dual problem is the minimization of an unconstrained, piecewise quadratic function. It involves a lower bound of lambda/sub 1/ , the smallest eigenvalue...

  17. Stacked spheres and lower bound theorem

    Indian Academy of Sciences (India)

    BASUDEB DATTA

    2011-11-20

    Nov 20, 2011 ... Preliminaries. Lower bound theorem. On going work. Definitions. An n-simplex is a convex hull of n + 1 affinely independent points. (called vertices) in some Euclidean space R. N . Stacked spheres and lower bound theorem. Basudeb Datta. Indian Institute of Science. 2 / 27 ...

  18. Exponential Lower Bounds For Policy Iteration

    OpenAIRE

    Fearnley, John

    2010-01-01

    We study policy iteration for infinite-horizon Markov decision processes. It has recently been shown policy iteration style algorithms have exponential lower bounds in a two player game setting. We extend these lower bounds to Markov decision processes with the total reward and average-reward optimality criteria.

  19. Upper Bounds on Numerical Approximation Errors

    DEFF Research Database (Denmark)

    Raahauge, Peter

    2004-01-01

    This paper suggests a method for determining rigorous upper bounds on approximationerrors of numerical solutions to infinite horizon dynamic programming models.Bounds are provided for approximations of the value function and the policyfunction as well as the derivatives of the value function...

  20. Bounds in the location-allocation problem

    DEFF Research Database (Denmark)

    Juel, Henrik

    1981-01-01

    Develops a family of stronger lower bounds on the objective function value of the location-allocation problem. Solution methods proposed to solve problems in location-allocation; Efforts to develop a more efficient bound solution procedure; Determination of the locations of the sources....

  1. New bounds for multi-dimensional packing

    NARCIS (Netherlands)

    S. Seiden; R. van Stee (Rob)

    2001-01-01

    textabstractNew upper and lower bounds are presented for a multi-dimensional generalization of bin packing called box packing. Several variants of this problem, including bounded space box packing, square packing, variable sized box packing and resource augmented box packing are also studied. The

  2. Impedance, zero energy wavefunction, and bound states

    CERN Document Server

    Martin, A

    1977-01-01

    The authors show that for the three-dimensional Schrodinger equation without spherical symmetry the existence of a bound state is related to the impossibility of solving a certain equation; it is further shown that some general conditions for the absence of bound states are readily obtained from this property. (13 refs).

  3. New bounds on isotropic Lorentz violation

    International Nuclear Information System (INIS)

    Carone, Christopher D.; Sher, Marc; Vanderhaeghen, Marc

    2006-01-01

    Violations of Lorentz invariance that appear via operators of dimension four or less are completely parametrized in the Standard Model Extension (SME). In the pure photonic sector of the SME, there are 19 dimensionless, Lorentz-violating parameters. Eighteen of these have experimental upper bounds ranging between 10 -11 and 10 -32 ; the remaining parameter, k-tilde tr , is isotropic and has a much weaker bound of order 10 -4 . In this Brief Report, we point out that k-tilde tr gives a significant contribution to the anomalous magnetic moment of the electron and find a new upper bound of order 10 -8 . With reasonable assumptions, we further show that this bound may be improved to 10 -14 by considering the renormalization of other Lorentz-violating parameters that are more tightly constrained. Using similar renormalization arguments, we also estimate bounds on Lorentz-violating parameters in the pure gluonic sector of QCD

  4. Bound-free Spectra for Diatomic Molecules

    Science.gov (United States)

    Schwenke, David W.

    2012-01-01

    It is now recognized that prediction of radiative heating of entering space craft requires explicit treatment of the radiation field from the infrared (IR) to the vacuum ultra violet (VUV). While at low temperatures and longer wavelengths, molecular radiation is well described by bound-bound transitions, in the short wavelength, high temperature regime, bound-free transitions can play an important role. In this work we describe first principles calculations we have carried out for bound-bound and bound-free transitions in N2, O2, C2, CO, CN, NO, and N2+. Compared to bound ]bound transitions, bound-free transitions have several particularities that make them different to deal with. These include more complicated line shapes and a dependence of emission intensity on both bound state diatomic and atomic concentrations. These will be discussed in detail below. The general procedure we used was the same for all species. The first step is to generate potential energy curves, transition moments, and coupling matrix elements by carrying out ab initio electronic structure calculations. These calculations are expensive, and thus approximations need to be made in order to make the calculations tractable. The only practical method we have to carry out these calculations is the internally contracted multi-reference configuration interaction (icMRCI) method as implemented in the program suite Molpro. This is a widely used method for these kinds of calculations, and is capable of generating very accurate results. With this method, we must first of choose which electrons to correlate, the one-electron basis to use, and then how to generate the molecular orbitals.

  5. A high-performance liquid chromatography assay for quantification of cardiac myosin heavy chain isoform protein expression.

    Science.gov (United States)

    Lemon, Douglas D; Papst, Philip J; Joly, Kristin; Plato, Craig F; McKinsey, Timothy A

    2011-01-01

    Stress signaling in the myocardium results in enhanced expression of fetal β-myosin heavy chain (β-MyHC) and reduced expression of adult α-myosin heavy chain (α-MyHC), with the net outcome of diminished myofibrillar ATPase activity and impaired contractility. Pharmacological approaches aimed at preventing this myosin isoform "switch" could provide therapeutic benefit to patients with heart failure. Myosin isoform protein expression is typically quantified using gel electrophoresis methods, which are time-consuming and prone to variability. Here we describe a facile, reversed-phase high-performance liquid chromatography (HPLC) method for rapidly determining the relative amounts of full-length α- and β-MyHC in rat hearts. The assay was validated using cardiac tissues from rats in which a key transcriptional regulator of MyHC expression, the thyroid hormone receptor, was pharmacologically manipulated. This novel assay should facilitate drug discovery efforts focused on the MyHC axis. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Drosophila UNC-45 prevents heat-induced aggregation of skeletal muscle myosin and facilitates refolding of citrate synthase

    Energy Technology Data Exchange (ETDEWEB)

    Melkani, Girish C.; Lee, Chi F.; Cammarato, Anthony [Department of Biology and the Molecular Biology Institute, San Diego State University, San Diego, CA 92182-4614 (United States); Bernstein, Sanford I., E-mail: sbernst@sciences.sdsu.edu [Department of Biology and the Molecular Biology Institute, San Diego State University, San Diego, CA 92182-4614 (United States)

    2010-05-28

    UNC-45 belongs to the UCS (UNC-45, CRO1, She4p) domain protein family, whose members interact with various classes of myosin. Here we provide structural and biochemical evidence that Escherichia coli-expressed Drosophila UNC-45 (DUNC-45) maintains the integrity of several substrates during heat-induced stress in vitro. DUNC-45 displays chaperone function in suppressing aggregation of the muscle myosin heavy meromyosin fragment, the myosin S-1 motor domain, {alpha}-lactalbumin and citrate synthase. Biochemical evidence is supported by electron microscopy, which reveals the first structural evidence that DUNC-45 prevents inter- or intra-molecular aggregates of skeletal muscle heavy meromyosin caused by elevated temperatures. We also demonstrate for the first time that UNC-45 is able to refold a denatured substrate, urea-unfolded citrate synthase. Overall, this in vitro study provides insight into the fate of muscle myosin under stress conditions and suggests that UNC-45 protects and maintains the contractile machinery during in vivo stress.

  7. Myosin content of single muscle fibers following short-term disuse and active recovery in young and old healthy men

    DEFF Research Database (Denmark)

    Hvid, Lars G; Brocca, Lorenza; Ørtenblad, Niels

    2017-01-01

    Short-term disuse and subsequent recovery affect whole muscle and single myofiber contractile function in young and old. While the loss and recovery of single myofiber specific force (SF) following disuse and rehabilitation has been shown to correlate with alterations in myosin concentrations...

  8. The tail domain of theAspergillus fumigatusclass V myosin MyoE orchestrates septal localization and hyphal growth.

    Science.gov (United States)

    Renshaw, Hilary; Vargas-Muñiz, José M; Juvvadi, Praveen R; Richards, Amber D; Waitt, Greg; Soderblom, Erik J; Moseley, M Arthur; Steinbach, William J

    2018-02-07

    Myosins are critical motor proteins that contribute to the secretory pathway, polarized growth, and cytokinesis. The globular tail domains of class V myosins have been shown to be important for cargo binding and actin cable organization. Additionally, phosphorylation plays a role in class V myosin cargo choice. Our previous studies on the class V myosin MyoE in the fungal pathogen Aspergillus fumigatus confirmed its requirement for normal morphology and virulence. However, the domains and molecular mechanisms governing the functions of MyoE remain unknown. Here, by analyzing tail mutants, we demonstrate that the tail is required for radial growth, conidiation, septation frequency and MyoE's location at the septum. Furthermore, MyoE is phosphorylated at multiple residues in vivo ; however, alanine substitution mutants revealed that no single phosphorylated residue was critical. Importantly, in the absence of the phosphatase calcineurin, an additional residue was phosphorylated in its tail domain. Mutation of this tail residue led to mislocalization of MyoE from the septa. This work reveals the importance of the MyoE tail domain and its phosphorylation/dephosphorylation in the growth and morphology of A. fumigatus . © 2018. Published by The Company of Biologists Ltd.

  9. Maintenance of muscle myosin levels in adult C. elegans requires both the double bromodomain protein BET-1 and sumoylation

    Directory of Open Access Journals (Sweden)

    Kate Fisher

    2013-10-01

    Attenuation of RAS-mediated signalling is a conserved process essential to control cell proliferation, differentiation, and apoptosis. Cooperative interactions between histone modifications such as acetylation, methylation and sumoylation are crucial for proper attenuation in C. elegans, implying that the proteins recognising these histone modifications could also play an important role in attenuation of RAS-mediated signalling. We sought to systematically identify these proteins and found BET-1. BET-1 is a conserved double bromodomain protein that recognises acetyl-lysines on histone tails and maintains the stable fate of various lineages. Unexpectedly, adults lacking both BET-1 and SUMO-1 are depleted of muscle myosin, an essential component of myofibrils. We also show that this muscle myosin depletion does not occur in all animals at a specific time, but rather that the penetrance of the phenotype increases with age. To gain mechanistic insights into this process, we sought to delay the occurrence of the muscle myosin depletion phenotype and found that it requires caspase activity and MEK-dependent signalling. We also performed transcription profiling on these mutants and found an up-regulation of the FGF receptor, egl-15, a tyrosine kinase receptor acting upstream of MEK. Consistent with a MEK requirement, we could delay the muscle phenotype by systemic or hypodermal knock down of egl-15. Thus, this work uncovered a caspase- and MEK-dependent mechanism that acts specifically on ageing adults to maintain the appropriate net level of muscle myosin.

  10. Myosin Vb mediated plasma membrane homeostasis regulates peridermal cell size and maintains tissue homeostasis in the zebrafish epidermis.

    Science.gov (United States)

    Sonal; Sidhaye, Jaydeep; Phatak, Mandar; Banerjee, Shamik; Mulay, Aditya; Deshpande, Ojas; Bhide, Sourabh; Jacob, Tressa; Gehring, Ines; Nuesslein-Volhard, Christiane; Sonawane, Mahendra

    2014-09-01

    The epidermis is a stratified epithelium, which forms a barrier to maintain the internal milieu in metazoans. Being the outermost tissue, growth of the epidermis has to be strictly coordinated with the growth of the embryo. The key parameters that determine tissue growth are cell number and cell size. So far, it has remained unclear how the size of epidermal cells is maintained and whether it contributes towards epidermal homeostasis. We have used genetic analysis in combination with cellular imaging to show that zebrafish goosepimples/myosin Vb regulates plasma membrane homeostasis and is involved in maintenance of cell size in the periderm, the outermost epidermal layer. The decrease in peridermal cell size in Myosin Vb deficient embryos is compensated by an increase in cell number whereas decrease in cell number results in the expansion of peridermal cells, which requires myosin Vb (myoVb) function. Inhibition of cell proliferation as well as cell size expansion results in increased lethality in larval stages suggesting that this two-way compensatory mechanism is essential for growing larvae. Our analyses unravel the importance of Myosin Vb dependent cell size regulation in epidermal homeostasis and demonstrate that the epidermis has the ability to maintain a dynamic balance between cell size and cell number.

  11. Universal Bounds for the Holevo Quantity, Coherent Information, and the Jensen-Shannon Divergence

    Science.gov (United States)

    Roga, Wojciech; Fannes, Mark; Życzkowski, Karol

    2010-07-01

    The mutual information between the sender of a classical message encoded in quantum carriers and a receiver is fundamentally limited by the Holevo quantity. Using strong subadditivity of entropy, we prove that the Holevo quantity is not larger than an exchange entropy. This implies an upper bound for coherent information. Moreover, restricting our attention to classical information, we bound the transmission distance between probability distributions by their entropic distance, which is a concave function of their Hellinger distance.

  12. Hierarchical order in wall-bounded shear turbulence

    International Nuclear Information System (INIS)

    Carbone, F.; Aubry, N.

    1996-01-01

    Since turbulence at realistic Reynolds numbers, such as those occurring in the atmosphere or in the ocean, involve a high number of modes that cannot be resolved computationally in the foreseeable future, there is a strong motivation for finding techniques which drastically decrease the number of such required modes, particularly under inhomogeneous conditions. The significance of this work is to show that wall-bounded shear turbulence, in its strongly inhomogeneous direction (normal to the wall), can be decomposed into one (or a few) space endash time mother mode(s), with each mother generating a whole family of modes by stretching symmetry. In other words, the generated modes are similar, dilated copies of their mother. In addition, we show that the nature of all previous modes strongly depends on the symmetry itself. These findings constitute the first scaling theory of inhomogeneous turbulence. copyright 1996 American Institute of Physics

  13. Optical nonlinearity and bistability in the bound exciton energy range of CdS

    International Nuclear Information System (INIS)

    Hoenig, T.; Gutowski, J.

    1988-01-01

    Under high excitation conditions thick CdS samples show pronounced broad-band nonlinear transmission in the bound exciton region and up to a wavelength of about 515 nm at cryo-temperatures. This behavior is only explainable in a model based on impurity neutralization and bound exciton creation. The suitability of these nonlinearities to yield optical bistability will be shown. Bistable operation is investigated in dependence of crystal thickness, impurity concentration, excitation density, wavelength, and temperature. A strong correlation to acceptor-bound exciton generation is obtained, and the explanation of this bistable operation fits well with that of the above mentioned transmission behavior. (author)

  14. Two-state thermal unfolding of a long dimeric coiled-coil: the Acanthamoeba myosin II rod.

    Science.gov (United States)

    Zolkiewski, M; Redowicz, M J; Korn, E D; Hammer, J A; Ginsburg, A

    1997-06-24

    Acanthamoeba myosin II rod is a long alpha-helical coiled-coil with a flexible hinge containing a helix-breaking proline. The thermal stability of the complete rod domain of myosin II (residues 849-1509), a mutant in which the hinge proline was replaced by alanine (P398A), and a mutant with the whole hinge region deleted (delta(384-408)) was studied in 0.6 and 2.2 M KCl, pH 7.5. In analytical ultracentrifugation studies, the purified myosin II rods sedimented as monodisperse dimers with sedimentation coefficients s(20,w) = 3.8 S (wild-type, Mr = 149,000) and 3.6 S (P398A and delta(384-408)). Circular dichroism (CD) and differential scanning calorimetry (DSC) showed that the thermal unfolding of the myosin II rod is reversible and highly cooperative. The unfolding of the rod is coupled to a dissociation of the chains, as shown by HPLC gel filtration at high temperatures and by the concentration dependence of the transition temperature. The CD and DSC data are consistent with a two-state mechanism (Tm approximately 40 degrees C, deltaH approximately 400 kcal/mol) in which the dimeric rod unfolds with concomitant formation of two unfolded monomers. We found no evidence for independent unfolding of the two rod domains that are separated by the hinge region. The only difference observed in the unfolding of the mutant rods from that of the wild type was a approximately 2 degrees C increase in the thermal stability of the hinge-deletion mutant. Thus, the mechanism of unfolding the Acanthamoeba myosin II rod is different from those of skeletal muscle myosin rod and tropomyosin, for which non-two-state thermal transitions have been observed. The cooperative unfolding of the entire coiled-coil rod of Acanthamoeba myosin II may underlie the previously reported regulatory coupling between its N-terminal head and C-terminal tail.

  15. Characterization of the minimum domain required for targeting budding yeast myosin II to the site of cell division

    Directory of Open Access Journals (Sweden)

    Tolliday Nicola J

    2006-06-01

    Full Text Available Abstract Background All eukaryotes with the exception of plants use an actomyosin ring to generate a constriction force at the site of cell division (cleavage furrow during mitosis and meiosis. The structure and filament forming abilities located in the C-terminal or tail region of one of the main components, myosin II, are important for localising the molecule to the contractile ring (CR during cytokinesis. However, it remains poorly understood how myosin II is recruited to the site of cell division and how this recruitment relates to myosin filament assembly. Significant conservation between species of the components involved in cytokinesis, including those of the CR, allows the use of easily genetically manipulated organisms, such as budding yeast (Saccharomyces cerevisiae, in the study of cytokinesis. Budding yeast has a single myosin II protein, named Myo1. Unlike most other class II myosins, the tail of Myo1 has an irregular coiled coil. In this report we use molecular genetics, biochemistry and live cell imaging to characterize the minimum localisation domain (MLD of budding yeast Myo1. Results We show that the MLD is a small region in the centre of the tail of Myo1 and that it is both necessary and sufficient for localisation of Myo1 to the yeast bud neck, the pre-determined site of cell division. Hydrodynamic measurements of the MLD, purified from bacteria or yeast, show that it is likely to exist as a trimer. We also examine the importance of a small region of low coiled coil forming probability within the MLD, which we call the hinge region. Removal of the hinge region prevents contraction of the CR. Using fluorescence recovery after photobleaching (FRAP, we show that GFP-tagged MLD is slightly more dynamic than the GFP-tagged full length molecule but less dynamic than the GFP-tagged Myo1 construct lacking the hinge region. Conclusion Our results define the intrinsic determinant for the localization of budding yeast myosin II and show

  16. Zinc-induced cardiomyocyte relaxation in a rat model of hyperglycemia is independent of myosin isoform

    Directory of Open Access Journals (Sweden)

    Yi Ting

    2012-11-01

    Full Text Available Abstract It has been reported previously that diabetic cardiomyopathy can be inhibited or reverted with chronic zinc supplementation. In the current study, we hypothesized that total cardiac calcium and zinc content is altered in early onset diabetes mellitus characterized in part as hyperglycemia (HG and that exposure of zinc ion (Zn2+ to isolated cardiomyocytes would enhance contraction-relaxation function in HG more so than in nonHG controls. To better control for differential cardiac myosin isoform expression as occurs in rodents after β-islet cell necrosis, hypothyroidism was induced in 16 rats resulting in 100% β-myosin heavy chain expression in the heart. β-Islet cell necrosis was induced in half of the rats by streptozocin administration. After 6 wks of HG, both HG and nonHG controls rats demonstrated similar myofilament performance measured as thin filament calcium sensitivity, native thin filament velocity in the myosin motility assay and contractile velocity and power. Extracellular Zn2+ reduced cardiomyocyte contractile function in both groups, but enhanced relaxation function significantly in the HG group compared to controls. Most notably, a reduction in diastolic sarcomere length with increasing pacing frequencies, i.e., incomplete relaxation, was more pronounced in the HG compared to controls, but was normalized with extracellular Zn2+ application. This is a novel finding implicating that the detrimental effect of HG on cardiomyocyte Ca2+ regulation can be amelioration by Zn2+. Among the many post-translational modifications examined, only phosphorylation of ryanodine receptor (RyR at S-2808 was significantly higher in HG compared to nonHG. We did not find in our hypothyroid rats any differentiating effects of HG on myofibrillar protein phosphorylation, lysine acetylation, O-linked N-acetylglucosamine and advanced glycated end-products, which are often implicated as complicating factors in cardiac performance due to HG. Our

  17. Parathyroid hormone promotes the disassembly of cytoskeletal actin and myosin in cultured osteoblastic cells: Mediation by cyclic AMP

    International Nuclear Information System (INIS)

    Egan, J.J.; Gronowicz, G.; Rodan, G.A.

    1991-01-01

    Parathyroid hormone (PTH) alters the shape of osteoblastic cells both in vivo and in vitro. In this study, we examined the effect of PTH on cytoskeletal actin and myosin, estimated by polyacrylamide gel electrophoresis of Triton X-100 (1%) nonextractable proteins. After 2-5 minutes, PTH caused a rapid and transient decrease of 50-60% in polymerized actin and myosin associated with the Triton X-100 nonextractable cytoskeleton. Polymerized actin returned to control levels by 30 min. The PTH effect was dose-dependent with an IC50 of about 1 nM, and was partially inhibited by the (3-34) PTH antagonist. PTH caused a rapid transient rise in cyclic AMP (cAMP) in these cells that peaked at 4 min, while the nadir in cytoskeletal actin and myosin was recorded around 5 min. The intracellular calcium chelator Quin-2/AM (10 microM) also decreased cytoskeletal actin and myosin, to the same extent as did PTH (100 nM). To distinguish between cAMP elevation and Ca++ reduction as mediators of PTH action, we measured the phosphorylation of the 20 kD (PI 4.9) myosin light chain in cells preincubated with [32P]-orthophosphate. The phosphorylation of this protein decreased within 2-3 min after PTH addition and returned to control levels after 5 min. The calcium ionophore A-23187 did not antagonize this PTH effect. Visualization of microfilaments with rhodamine-conjugated phalloidin showed that PTH altered the cytoskeleton by decreasing the number of stress fibers. These changes in the cytoskeleton paralleled changes in the shape of the cells from a spread configuration to a stellate form with retracting processes. The above findings indicate that the alteration in osteoblast shape produced by PTH involve relatively rapid and transient changes in cytoskeletal organization that appear to be mediated by cAMP

  18. Process interpretation of current entropic bounds

    Science.gov (United States)

    Nardini, Cesare; Touchette, Hugo

    2018-01-01

    We show for Markov diffusion processes that the quadratic entropic bound, recently derived for the rate functions of nonequilibrium currents, can be seen as being produced by an effective process that creates current fluctuations in a sub-optimal way by modifying only the non-reversible part of the drift or force of the process considered while keeping its reversible part constant. This provides a clear interpretation of the bound in terms of a physical process, which explains, among other things, its relation to the fluctuation relation, linear response, and reversible limits. The existence of more general quadratic bounds, and related uncertainty relations, for physical quantities other than currents is also discussed.

  19. Lower bound for the nuclear kinetic energy

    Energy Technology Data Exchange (ETDEWEB)

    Dehesa, J.S. (Granada Univ. (Spain). Dept. de Fisica Nuclear); Galvez, F.J. (Granada Univ. (Spain). Dept. de Fisica Teorica)

    1985-06-27

    We argue that the kinetic energy of a many-fermion system is bounded from below by Kqsup(-2/3)A sup(5/3) / , with K = 0.565 where q is the number of spin states available to each particle and sup(1/2) is the root mean square radius of the single-particle density. A simple lower bound for the nuclear kinetic energy is found. Numerical values of the bound for several nuclei are shown, and a comparison with some self-consistent calculations and some pseudo-empirical values is made.

  20. Remarks on Bousso's covariant entropy bound

    CERN Document Server

    Mayo, A E

    2002-01-01

    Bousso's covariant entropy bound is put to the test in the context of a non-singular cosmological solution of general relativity found by Bekenstein. Although the model complies with every assumption made in Bousso's original conjecture, the entropy bound is violated due to the occurrence of negative energy density associated with the interaction of some the matter components in the model. We demonstrate how this property allows for the test model to 'elude' a proof of Bousso's conjecture which was given recently by Flanagan, Marolf and Wald. This corroborates the view that the covariant entropy bound should be applied only to stable systems for which every matter component carries positive energy density.

  1. Quasi-bound states in continuum

    International Nuclear Information System (INIS)

    Nakamura, Hiroaki; Hatano, Naomichi; Garmon, Sterling; Petrosky, Tomio

    2007-08-01

    We report the prediction of quasi-bound states (resonant states with very long lifetimes) that occur in the eigenvalue continuum of propagating states for a wide region of parameter space. These quasi-bound states are generated in a quantum wire with two channels and an adatom, when the energy bands of the two channels overlap. A would-be bound state that lays just below the upper energy band is slightly destabilized by the lower energy band and thereby becomes a resonant state with a very long lifetime (a second QBIC lays above the lower energy band). (author)

  2. Anisotropy of Crumbs and aPKC drives myosin cable assembly during tube formation.

    Science.gov (United States)

    Röper, Katja

    2012-11-13

    The formation of tubular structures from epithelial sheets is a key process of organ formation in all animals, but the cytoskeletal rearrangements that cause the cell shape changes that drive tubulogenesis are not well understood. Using live imaging and super-resolution microscopy to analyze the tubulogenesis of the Drosophila salivary glands, I find that an anisotropic plasma membrane distribution of the protein Crumbs, mediated by its large extracellular domain, determines the subcellular localization of a supracellular actomyosin cable in the cells at the placode border, with myosin II accumulating at edges where Crumbs is lowest. Laser ablation shows that the cable is under increased tension, implying an active involvement in the invagination process. Crumbs anisotropy leads to anisotropic distribution of aPKC, which in turn can negatively regulate Rok, thus preventing the formation of a cable where Crumbs and aPKC are localized. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. [Peptide inhibitors of myosin light chain kinase. Development of peptidase resistant analogues].

    Science.gov (United States)

    Sekridova, A V; Sidorova, M V; Az'muko, A A; Molokoedov, A S; Bushuev, V N; Marchenko, A V; Shcherbakova, O V; Shirinskiĭ, V P; Bespalova, Zh D

    2010-01-01

    Myosin light chain kinase (MLCK) is the key regulator of various forms of cell motility including endothelial and epithelial permeability in particular. One of the potential MLCK inhibitors to be used in humans is a membrane permeable peptide H-RKKYKYRRK-NH2 (L-PIK). In present work we used solid phase peptide synthesis and Fmoc-technology to produce five modifications of L-PIK. Based on (1)H NMR analysis revealed that these peptides demonstrated improved resistance to degradation in blood plasma. One of de novo synthesized peptides, L-[MeArg(1)]PIK inhibited MLCK activity in vitro with the same efficiency as L-PIK whereas other modified peptides showed reduced inhibitory activity. D-amino acid analog of PIK was the least active inhibitor. Thus, we have demonstrated the possibility to produce an effective MLCK peptide inhibitor with increased resistance to biodegradation that is suitable for further pharmacological development.

  4. Dynamic light scattering study of the effect of Mg2+ and ATP on synthetic myosin filaments

    Science.gov (United States)

    Fujime, Satoru; Takayama, Sei-ichi

    1995-01-01

    The dynamic light scattering (DLS) method provides us with information about the apparent diffusion coefficient, Dapp, as well as the static scattering intensity, Is. For long but thin rods with length L and diameter d (i.e., KL >> 1 but Kd different from that of Is. By means of DLS were studied synthetic myosin filaments of vertebrate skeletal muscle in solution at pH 8.3. It appeared that Mg2+ ions induced lengthening and thickening of the filaments whereas ATP (and ADP) induced shortening (depolymerization) of the filaments. When ATP was added to the filament preparation in the presence of Mg2+ ions, thinning of the filaments (or splitting into subfilaments) occurred prior to shortening (depolymerization).

  5. Acute quadriplegic myopathy with loss of thick (myosin) filaments following heart transplantation.

    Science.gov (United States)

    Perea, M; Picón, M; Miró, O; Orús, J; Roig, E; Grau, J M

    2001-10-01

    Acute quadriplegic myopathy with loss of thick (myosin) filaments (AQM-LTF) is an acute toxic myopathy observed in critically ill patients and is characterized by proximal or diffuse weakness of extremities and difficulty in weaning from mechanical ventilation. In recent years, this myopathy has been described in transplanted patients, although only 5 cases have been reported following heart transplantation. We present 3 new cases and review the previous literature. We conclude that the clinical picture and outcome of AQM-LTF in heart-transplanted patients do not differ from those observed in other critically ill patients (transplanted and non-transplanted). Therefore, because AQM-LTF is often clinically suspected muscle biopsy should be quickly performed to confirm the diagnosis so that physical therapy may begin as soon as possible.

  6. Enhanced protein electrophoresis technique for separating human skeletal muscle myosin heavy chain isoforms

    Science.gov (United States)

    Bamman, M. M.; Clarke, M. S.; Talmadge, R. J.; Feeback, D. L.

    1999-01-01

    Talmadge and Roy (J. Appl. Physiol. 1993, 75, 2337-2340) previously established a sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE) protocol for separating all four rat skeletal muscle myosin heavy chain (MHC) isoforms (MHC I, IIa, IIx, IIb); however, when applied to human muscle, the type II MHC isoforms (Ila, IIx) are not clearly distinguished. In this brief paper we describe a modification of the SDS-PAGE protocol which yields distinct and consistent separation of all three adult human MHC isoforms (MHC I, IIa, IIx) in a minigel system. MHC specificity of each band was confirmed by Western blot using three monoclonal IgG antibodies (mAbs) immunoreactive against MHCI (mAb MHCs, Novacastra Laboratories), MHCI+IIa (mAb BF-35), and MHCIIa+IIx (mAb SC-71). Results provide a valuable SDS-PAGE minigel technique for separating MHC isoforms in human muscle without the difficult task of casting gradient gels.

  7. Dimerization specificity of adult and neonatal chicken skeletal muscle myosin heavy chain rods.

    Science.gov (United States)

    Singh, Sheetal; Bandman, Everett

    2006-04-18

    The dimerization specificity of the recombinantly expressed and purified rod domain of adult and neonatal chicken myosin heavy chain was analyzed using metal chelation chromatography. Our results indicate that full-length adult and neonatal rods preferentially formed homodimers when renatured from an equimolar mixture of the two isoforms denatured in guanidine hydrochloride. The contribution made toward the dimerization specificity by subdomains of the rod has been addressed by making a chimeric protein consisting of the subfragment 2 (S2) region of the adult isoform and the light meromyosin region of the neonatal isoform. The proportion of heterodimers formed in exchange experiments between the chimera and the neonatal and adult rods rose with increase in the sequence homology between the two exchanging proteins. This suggests that multiple regions of the rod domain of chicken MyHC including S2 can contribute toward dimerization specificity.

  8. Strongly Coupled Chameleons and the Neutronic Quantum Bouncer

    International Nuclear Information System (INIS)

    Brax, Philippe; Pignol, Guillaume

    2011-01-01

    We consider the potential detection of chameleons using bouncing ultracold neutrons. We show that the presence of a chameleon field over a planar plate would alter the energy levels of ultracold neutrons in the terrestrial gravitational field. When chameleons are strongly coupled to nuclear matter, β > or approx. 10 8 , we find that the shift in energy levels would be detectable with the forthcoming GRANIT experiment, where a sensitivity of the order of 1% of a peV is expected. We also find that an extremely large coupling β > or approx. 10 11 would lead to new bound states at a distance of order 2 μm, which is already ruled out by previous Grenoble experiments. The resulting bound, β 11 , is already 3 orders of magnitude better than the upper bound, β 14 , from precision tests of atomic spectra.

  9. Comparable stocks, boundedly rational stock markets and IPO entry rates.

    Directory of Open Access Journals (Sweden)

    Jay Chok

    Full Text Available In this study, we examine how initial public offerings (IPO entry rates are affected when stock markets are boundedly rational and IPO firms infer information from their counterparts in the market. We hypothesize a curvilinear relationship between the number of comparable stocks and initial public offerings (IPO entry rates into the NASDAQ Stock Exchange. Furthermore, we argue that trading volume and changes in stock returns partially mediates the relationship between the number of comparable stocks and IPO entry rates. The statistical evidence provides strong support for the hypotheses.

  10. Comparable stocks, boundedly rational stock markets and IPO entry rates.

    Science.gov (United States)

    Chok, Jay; Qian, Jifeng

    2013-01-01

    In this study, we examine how initial public offerings (IPO) entry rates are affected when stock markets are boundedly rational and IPO firms infer information from their counterparts in the market. We hypothesize a curvilinear relationship between the number of comparable stocks and initial public offerings (IPO) entry rates into the NASDAQ Stock Exchange. Furthermore, we argue that trading volume and changes in stock returns partially mediates the relationship between the number of comparable stocks and IPO entry rates. The statistical evidence provides strong support for the hypotheses.

  11. Electron Capture Dissociation of Weakly Bound Polypeptide Polycationic Complexes

    DEFF Research Database (Denmark)

    Haselmann, Kim F; Jørgensen, Thomas J D; Budnik, Bogdan A

    2002-01-01

    as well as specific complexes of modified glycopeptide antibiotics with their target peptide. The weak nature of bonding is substantiated by blackbody infrared dissociation, low-energy collisional excitation and force-field simulations. The results are consistent with a non-ergodic ECD cleavage mechanism.......We have previously reported that, in electron capture dissociation (ECD), rupture of strong intramolecular bonds in weakly bound supramolecular aggregates can proceed without dissociation of weak intermolecular bonds. This is now illustrated on a series of non-specific peptide-peptide dimers...

  12. Noninvasive Assessment of Skeletal Muscle Myosin Heavy Chain Expression in Trained and Untrained Men.

    Science.gov (United States)

    Fry, Andrew C; Housh, Terry J; Cramer, Joel B; Weir, Joseph P; Beck, Travis W; Schilling, Brian K; Miller, Jonathan D; Nicoll, Justin X

    2017-09-01

    Fry, AC, Housh, TJ, Cramer, JB, Weir, JP, Beck, TW, Schilling, BK, Miller, JD, and Nicoll, JX. Noninvasive assessment of skeletal muscle myosin heavy chain expression in trained and untrained men. J Strength Cond Res 31(9): 2355-2362, 2017-Numerous conditions and types of physical activity (e.g., exercise, aging, and muscle-related diseases) can influence muscle fiber types and the proteins expressed. To date, muscle fibers can only be characterized by actually obtaining a tissue sample using the invasive muscle biopsy procedure. Mechanomyography (MMG) is the assessment of the vibration properties of contracting skeletal muscle and has been proposed as a possible noninvasive method for muscle fiber analysis. Therefore, the purpose of this project was to examine the feasibility of using MMG and muscle performance measures to noninvasively assess muscle fiber characteristics. Fifteen men (5 endurance-trained, 5 weight-trained, and 5 sedentary) provided muscle samples from their vastus lateralis muscle. These samples were analyzed for relative myosin heavy chain (MHC) protein expression, which is highly correlated with % muscle fiber type areas. Additionally, each subject performed several muscle performance tests, and MMG of the quadriceps was assessed during a knee extension exercise. Multiple regression was used to develop prediction equations for determining relative muscle content of MHC types I, IIa, and IIx. A combination of MMG and knee extension performance variables estimated types I, IIa, and IIx MHCs with approximately 80% accuracy. Although preliminary, these data suggest that muscle performance tests in addition to MMG assessments during a simple muscle performance task (knee extension) can be used to estimate muscle fiber type composition in a healthy male population. Such methods could ultimately be used to noninvasively monitor muscle health and fitness.

  13. Myosin isoform fiber type and fiber size in the tail of the Virginia opossum (Didelphis virginiana).

    Science.gov (United States)

    Hazimihalis, P J; Gorvet, M A; Butcher, M T

    2013-01-01

    Muscle fiber type is a well studied property in limb muscles, however, much less is understood about myosin heavy chain (MHC) isoform expression in caudal muscles of mammalian tails. Didelphid marsupials are an interesting lineage in this context as all species have prehensile tails, but show a range of tail-function depending on either their arboreal or terrestrial locomotor habits. Differences in prehensility suggest that MHC isoform fiber types may also be different, in that terrestrial opossums may have a large distribution of oxidative fibers for object carrying tasks instead of faster, glycolytic fiber types expected in mammals with long tails. To test this hypothesis, MHC isoform fiber type and their regional distribution (proximal/transitional/distal) were determined in the tail of the Virginia opossum (Didelphis virginiana). Fiber types were determined by a combination of myosin-ATPase histochemistry, immunohistochemistry, and SDS-PAGE. Results indicate a predominance of the fast MHC-2A and -2X isoforms in each region of the tail. The presence of two fast isoforms, in addition to the slow MHC-1 isoform, was confirmed by SDS-PAGE analysis. The overall MHC isoform fiber type distribution for the tail was: 25% MHC-1, 71% MHC-2A/X hybrid, and 4% MHC-1/2A hybrid. Oxidative MHC-2A/X isoform fibers were found to be relatively large in cross-section compared to slow, oxidative MHC-1 and MHC-1/2A hybrid fibers. A large percentage of fast MHC-2A/X hybrids fibers may be suggestive of an evolutionary transition in MHC isoform distribution (fast-to-slow fiber type) in the tail musculature of an opossum with primarily a terrestrial locomotor habit and adaptive tail-function. Copyright © 2012 Wiley Periodicals, Inc.

  14. Myosin Va becomes a low duty ratio motor in the inhibited form.

    Science.gov (United States)

    Sato, Osamu; Li, Xiang-Dong; Ikebe, Mitsuo

    2007-05-04

    Vertebrate myosin Va is a typical processive motor with high duty ratio. Recent studies have revealed that the actin-activated ATPase activity of the full-length myosin Va (M5aFull) is inhibited at a low [Ca(2+)], which is due to the formation of a folded conformation of M5aFull. To clarify the underlying inhibitory mechanism, we analyzed the actin-activated ATP hydrolysis mechanism of the M5aFull at the inhibited and the activated states, respectively. Marked differences were found in the hydrolysis, P(i) release, and ADP release steps between the activated and the inhibited states. The kinetic constants of these steps of the activated state were similar to those of the unregulated S1 construct, in which the rate-limiting step was the ADP release step. On the other hand, the P(i) release rate from acto-M5aFull was decreased in EGTA by >1,000-fold, which makes this step the rate-limiting step for the actin-activated ATP hydrolysis cycle of M5aFull. The ADP off rate from acto-M5aFull was decreased by approximately 10-fold, and the equilibrium between the prehydrolysis state and the post hydrolysis state was shifted toward the former state in the inhibited state of M5aFull. Because of these changes, M5aFull spends a majority of the ATP hydrolysis cycling time in the weak actin binding state. The present results indicate that M5aFull molecules at a low [Ca(2+)] is inhibited as a cargo transporter not only due to the decrease in the cross-bridge cycling rate but also due to the decrease in the duty ratio thus being dissociated from actin.

  15. The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage

    Directory of Open Access Journals (Sweden)

    Pradeep K. Luther

    2014-12-01

    Full Text Available Myosin filaments in vertebrate striated muscle have a long roughly cylindrical backbone with cross-bridge projections on the surfaces of both halves except for a short central bare zone. In the middle of this central region the filaments are cross-linked by the M-band which holds them in a well-defined hexagonal lattice in the muscle A-band. During muscular contraction the M-band-defined rotation of the myosin filaments around their long axes influences the interactions that the cross-bridges can make with the neighbouring actin filaments. We can visualise this filament rotation by electron microscopy of thin cross-sections in the bare-region immediately adjacent to the M-band where the filament profiles are distinctly triangular. In the muscles of teleost fishes, the thick filament triangular profiles have a single orientation giving what we call the simple lattice. In other vertebrates, for example all the tetrapods, the thick filaments have one of two orientations where the triangles point in opposite directions (they are rotated by 60° or 180° according to set rules. Such a distribution cannot be developed in an ordered fashion across a large 2D lattice, but there are small domains of superlattice such that the next-nearest neighbouring thick filaments often have the same orientation. We believe that this difference in the lattice forms can lead to different contractile behaviours. Here we provide a historical review, and when appropriate cite recent work related to the emergence of the simple and superlattice forms by examining the muscles of several species ranging back to primitive vertebrates and we discuss the functional differences that the two lattice forms may have.

  16. Myosin VIIA mutation screening in 189 Usher syndrome type 1 patients

    Energy Technology Data Exchange (ETDEWEB)

    Weston, M.D.; Kelley, P.M.; Overbeck, L.D. [Univ. of Nebraska Medical Center, Omaha, NE (United States)] [and others

    1996-11-01

    Usher syndrome type 1b (USH1B) is an autosomal recessive disorder characterized by congenital profound hearing loss, vestibular abnormalities, and retinitis pigmentosa. The disorder has recently been shown to be caused by mutations in the myosin VIIa gene (MYO7A) located on 11q14. In the current study, a panel of 189 genetically independent Usher I cases were screened for the presence of mutations in the N-terminal coding portion of the motor domain of MYO7A by heteroduplex analysis of 14 exons. Twenty-three mutations were found segregating with the disease in 20 families. Of the 23 mutations, 13 were unique, and 2 of the 13 unique mutations (Arg212His and Arg212Cys) accounted for the greatest percentage of observed mutant alleles (8/23, 31%). Six of the 13 mutations caused premature stop codons, 6 caused changes in the amino acid sequence of the myosin VIIa protein, and 1 resulted in a splicing defect. Three patients were homozygotes or compound heterozygotes for mutant alleles; these three cases were Tyr333Stop/Tyr333Stop, Arg212His-Arg302His/Arg212His-Arg302His, and IVS13nt-8c{r_arrow}g/ G1u450Gln. All the other USH1B mutations observed were simple heterozygotes, and it is presumed that the mutation on the other allele is present in the unscreened regions of the gene. None of the mutations reported here were observed in 96 unrelated control samples, although several polymorphisms were detected. These results add three patients to a single case reported previously where mutations have been found in both alleles and raises the total number of unique mutations in MYO7A to 16. 22 refs., 4 figs., 3 tabs.

  17. Interaction between cardiac myosin-binding protein C and formin Fhod3.

    Science.gov (United States)

    Matsuyama, Sho; Kage, Yohko; Fujimoto, Noriko; Ushijima, Tomoki; Tsuruda, Toshihiro; Kitamura, Kazuo; Shiose, Akira; Asada, Yujiro; Sumimoto, Hideki; Takeya, Ryu

    2018-04-23

    Mutations in cardiac myosin-binding protein C (cMyBP-C) are a major cause of familial hypertrophic cardiomyopathy. Although cMyBP-C has been considered to regulate the cardiac function via cross-bridge arrangement at the C-zone of the myosin-containing A-band, the mechanism by which cMyBP-C functions remains unclear. We identified formin Fhod3, an actin organizer essential for the formation and maintenance of cardiac sarcomeres, as a cMyBP-C-binding protein. The cardiac-specific N-terminal Ig-like domain of cMyBP-C directly interacts with the cardiac-specific N-terminal region of Fhod3. The interaction seems to direct the localization of Fhod3 to the C-zone, since a noncardiac Fhod3 variant lacking the cMyBP-C-binding region failed to localize to the C-zone. Conversely, the cardiac variant of Fhod3 failed to localize to the C-zone in the cMyBP-C-null mice, which display a phenotype of hypertrophic cardiomyopathy. The cardiomyopathic phenotype of cMyBP-C-null mice was further exacerbated by Fhod3 overexpression with a defect of sarcomere integrity, whereas that was partially ameliorated by a reduction in the Fhod3 protein levels, suggesting that Fhod3 has a deleterious effect on cardiac function under cMyBP-C-null conditions where Fhod3 is aberrantly mislocalized. Together, these findings suggest the possibility that Fhod3 contributes to the pathogenesis of cMyBP-C-related cardiomyopathy and that Fhod3 is critically involved in cMyBP-C-mediated regulation of cardiac function via direct interaction.

  18. Investigation of flexibility in Myosin V using a new 3D mechanical model

    Science.gov (United States)

    Haghshenas-Jaryani, Mahdi

    2012-02-01

    This paper presents the development of a three dimensional rigid multibody model for the simulation and analysis of motor protein locomotion. The interesting aspect of this model is that it retains the mass properties, in contrast to the commonly used models which omit mass properties at the nano scale. The disproportionate size of the small mass of Myosin V relative to the large viscous friction forces requires a small integration step size that leads to a long simulation run time; however, the proposed model can be numerically integrated in a reasonable amount of time. This paper discusses modeling flexibility in the protein as an extension of the original rigid body model. Empirical studies have shown that Myosin V's neck domain can be considered as three pairs of tandem elements called IQ motifs which can bending at junctures between them. Therefore, each neck is modeled by three rigid bodies connected by ball-and-socket joints together, rather than single rigid body has been used in the previous works. Euler parameters are used to model the orientation of bodies in order to eliminate singularities in the description of orientation. In order to accomplish this, the equations of motion are reduced to minimal form using changing holonomic and non-holonomic constraints applied to the model which represent the normalization of the Euler parameters as well as contact and impact non-penetration conditions. The differences between the dynamic behavior of the new mechanical model, with flexible neck domains, and the original rigid body model are compared using simulation results.

  19. Protective Effects of Clenbuterol against Dexamethasone-Induced Masseter Muscle Atrophy and Myosin Heavy Chain Transition.

    Science.gov (United States)

    Umeki, Daisuke; Ohnuki, Yoshiki; Mototani, Yasumasa; Shiozawa, Kouichi; Suita, Kenji; Fujita, Takayuki; Nakamura, Yoshiki; Saeki, Yasutake; Okumura, Satoshi

    2015-01-01

    Glucocorticoid has a direct catabolic effect on skeletal muscle, leading to muscle atrophy, but no effective pharmacotherapy is available. We reported that clenbuterol (CB) induced masseter muscle hypertrophy and slow-to-fast myosin heavy chain (MHC) isoform transition through direct muscle β2-adrenergic receptor stimulation. Thus, we hypothesized that CB would antagonize glucocorticoid (dexamethasone; DEX)-induced muscle atrophy and fast-to-slow MHC isoform transition. We examined the effect of CB on DEX-induced masseter muscle atrophy by measuring masseter muscle weight, fiber diameter, cross-sectional area, and myosin heavy chain (MHC) composition. To elucidate the mechanisms involved, we used immunoblotting to study the effects of CB on muscle hypertrophic signaling (insulin growth factor 1 (IGF1) expression, Akt/mammalian target of rapamycin (mTOR) pathway, and calcineurin pathway) and atrophic signaling (Akt/Forkhead box-O (FOXO) pathway and myostatin expression) in masseter muscle of rats treated with DEX and/or CB. Masseter muscle weight in the DEX-treated group was significantly lower than that in the Control group, as expected, but co-treatment with CB suppressed the DEX-induced masseter muscle atrophy, concomitantly with inhibition of fast-to-slow MHC isoforms transition. Activation of the Akt/mTOR pathway in masseter muscle of the DEX-treated group was significantly inhibited compared to that of the Control group, and CB suppressed this inhibition. DEX also suppressed expression of IGF1 (positive regulator of muscle growth), and CB attenuated this inhibition. Myostatin protein expression was unchanged. CB had no effect on activation of the Akt/FOXO pathway. These results indicate that CB antagonizes DEX-induced muscle atrophy and fast-to-slow MHC isoform transition via modulation of Akt/mTOR activity and IGF1 expression. CB might be a useful pharmacological agent for treatment of glucocorticoid-induced muscle atrophy.

  20. Protective Effects of Clenbuterol against Dexamethasone-Induced Masseter Muscle Atrophy and Myosin Heavy Chain Transition.

    Directory of Open Access Journals (Sweden)

    Daisuke Umeki

    Full Text Available Glucocorticoid has a direct catabolic effect on skeletal muscle, leading to muscle atrophy, but no effective pharmacotherapy is available. We reported that clenbuterol (CB induced masseter muscle hypertrophy and slow-to-fast myosin heavy chain (MHC isoform transition through direct muscle β2-adrenergic receptor stimulation. Thus, we hypothesized that CB would antagonize glucocorticoid (dexamethasone; DEX-induced muscle atrophy and fast-to-slow MHC isoform transition.We examined the effect of CB on DEX-induced masseter muscle atrophy by measuring masseter muscle weight, fiber diameter, cross-sectional area, and myosin heavy chain (MHC composition. To elucidate the mechanisms involved, we used immunoblotting to study the effects of CB on muscle hypertrophic signaling (insulin growth factor 1 (IGF1 expression, Akt/mammalian target of rapamycin (mTOR pathway, and calcineurin pathway and atrophic signaling (Akt/Forkhead box-O (FOXO pathway and myostatin expression in masseter muscle of rats treated with DEX and/or CB.Masseter muscle weight in the DEX-treated group was significantly lower than that in the Control group, as expected, but co-treatment with CB suppressed the DEX-induced masseter muscle atrophy, concomitantly with inhibition of fast-to-slow MHC isoforms transition. Activation of the Akt/mTOR pathway in masseter muscle of the DEX-treated group was significantly inhibited compared to that of the Control group, and CB suppressed this inhibition. DEX also suppressed expression of IGF1 (positive regulator of muscle growth, and CB attenuated this inhibition. Myostatin protein expression was unchanged. CB had no effect on activation of the Akt/FOXO pathway. These results indicate that CB antagonizes DEX-induced muscle atrophy and fast-to-slow MHC isoform transition via modulation of Akt/mTOR activity and IGF1 expression. CB might be a useful pharmacological agent for treatment of glucocorticoid-induced muscle atrophy.

  1. Strongly-MDS convolutional codes

    NARCIS (Netherlands)

    Gluesing-Luerssen, H; Rosenthal, J; Smarandache, R

    Maximum-distance separable (MDS) convolutional codes have the property that their free distance is maximal among all codes of the same rate and the same degree. In this paper, a class of MDS convolutional codes is introduced whose column distances reach the generalized Singleton bound at the

  2. Tight Bounds for Distributed Functional Monitoring

    DEFF Research Database (Denmark)

    Woodruff, David P.; Zhang, Qin

    2011-01-01

    $, our bound resolves their main open question. Our lower bounds are based on new direct sum theorems for approximate majority, and yield significant improvements to problems in the data stream model, improving the bound for estimating $F_p, p > 2,$ in $t$ passes from $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{2/p......} t))$ to $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{4/p} t))$, giving the first bound for estimating $F_0$ in $t$ passes of $\\Omega(1/(\\eps^2 t))$ bits of space that does not use the gap-hamming problem, and showing a distribution for the gap-hamming problem with high external information cost or super-polynomial......We resolve several fundamental questions in the area of distributed functional monitoring, initiated by Cormode, Muthukrishnan, and Yi (SODA, 2008). In this model there are $k$ sites each tracking their input and communicating with a central coordinator that continuously maintain an approximate...

  3. X-ray diffraction studies of cross-bridges weakly bound to actin in relaxed skinned fibers of rabbit psoas muscle.

    Science.gov (United States)

    Xu, S; Malinchik, S; Gilroy, D; Kraft, T; Brenner, B; Yu, L C

    1997-11-01

    X-ray diffraction patterns were obtained from skinned rabbit psoas muscle under relaxing and rigor conditions over a wide range of ionic strengths (50-170 mM) and temperatures (1 degree C-30 degrees C). For the first time, an intensification of the first actin-based layer line is observed in the relaxed muscle. The intensification, which increases with decreasing ionic strength at various temperatures, including 30 degrees C, parallels the formation of weakly attached cross-bridges in the relaxed muscle. However, the overall intensities of the actin-based layer lines are low. Furthermore, the level of diffuse scattering, presumably a measure of disorder among the cross-bridges, is little affected by changing ionic strength at a given temperature. The results suggest that the intensification of the first actin layer line is most likely due to the cross-bridges weakly bound to actin, and that the orientations of the weakly attached cross-bridges are hardly distinguishable from the detached cross-bridges. This suggests that the orientations of the weakly attached cross-bridges are not precisely defined with respect to the actin helix, i.e., nonstereospecific. Intensities of the myosin-based layer lines are only marginally affected by changing ionic strength, but markedly by temperature. The results could be explained if in a relaxed muscle the cross-bridges are distributed between a helically ordered and a disordered population with respect to myosin filament structure. Within the disordered population, some are weakly attached to actin and others are detached. The fraction of cross-bridges in the helically ordered assembly is primarily a function of temperature, while the distribution between the weakly attached and the detached within the disordered population is mainly affected by ionic strength. Some other notable features in the diffraction patterns include a approximately 1% decrease in the pitch of the myosin helix as the temperature is raised from 4 degrees C

  4. Numerical Bounds on the Price of Anarchy

    Directory of Open Access Journals (Sweden)

    Louis de Grange

    2017-01-01

    Full Text Available Theoretical upper bounds for price of anarchy have been calculated in previous studies. We present an empirical analysis for the price of anarchy for congested transportation networks; different network sizes and demand levels are considered for each network. We obtain a maximum price of anarchy for the cases studied, which is notably lower than the theoretical bounds reported in the literature. This result should be carefully considered in the design and implementation of road pricing mechanisms for cities.

  5. Learning Intelligent Dialogs for Bounding Box Annotation

    OpenAIRE

    Konyushkova, Ksenia; Uijlings, Jasper; Lampert, Christoph; Ferrari, Vittorio

    2017-01-01

    We introduce Intelligent Annotation Dialogs for bounding box annotation. We train an agent to automatically choose a sequence of actions for a human annotator to produce a bounding box in a minimal amount of time. Specifically, we consider two actions: box verification [37], where the annotator verifies a box generated by an object detector, and manual box drawing. We explore two kinds of agents, one based on predicting the probability that a box will be positively verified, and the other bas...

  6. New Spectral Features from Bound Dark Matter

    DEFF Research Database (Denmark)

    Catena, Riccardo; Kouvaris, Chris

    2016-01-01

    We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments...... with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section....

  7. Error Bounds: Necessary and Sufficient Conditions

    Czech Academy of Sciences Publication Activity Database

    Outrata, Jiří; Kruger, A.Y.; Fabian, Marián; Henrion, R.

    2010-01-01

    Roč. 18, č. 2 (2010), s. 121-149 ISSN 1877-0533 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506; CEZ:AV0Z10190503 Keywords : Error bounds * Calmness * Subdifferential * Slope Subject RIV: BA - General Mathematics Impact factor: 0.333, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/outrata-error bounds necessary and sufficient conditions.pdf

  8. Generalized surface tension bounds in vacuum decay

    Science.gov (United States)

    Masoumi, Ali; Paban, Sonia; Weinberg, Erick J.

    2018-02-01

    Coleman and De Luccia (CDL) showed that gravitational effects can prevent the decay by bubble nucleation of a Minkowski or AdS false vacuum. In their thin-wall approximation this happens whenever the surface tension in the bubble wall exceeds an upper bound proportional to the difference of the square roots of the true and false vacuum energy densities. Recently it was shown that there is another type of thin-wall regime that differs from that of CDL in that the radius of curvature grows substantially as one moves through the wall. Not only does the CDL derivation of the bound fail in this case, but also its very formulation becomes ambiguous because the surface tension is not well defined. We propose a definition of the surface tension and show that it obeys a bound similar in form to that of the CDL case. We then show that both thin-wall bounds are special cases of a more general bound that is satisfied for all bounce solutions with Minkowski or AdS false vacua. We discuss the limit where the parameters of the theory attain critical values and the bound is saturated. The bounce solution then disappears and a static planar domain wall solution appears in its stead. The scalar field potential then is of the form expected in supergravity, but this is only guaranteed along the trajectory in field space traced out by the bounce.

  9. On Pure and (approximate) Strong Equilibria of Facility Location Games

    DEFF Research Database (Denmark)

    Hansen, Thomas Dueholm; Telelis, Orestis A.

    2008-01-01

    We study social cost losses in Facility Location games, where n selfish agents install facilities over a network and connect to them, so as to forward their local demand (expressed by a non-negative weight per agent). Agents using the same facility share fairly its installation cost, but every ag......-approximate (e = 2.718...) strong equilibria and an upper bound of O(ln W) on SPoA (W is the sum of agents’ weights), which becomes tight Θ(ln n) for unweighted agents. Center for Algorithmic Game Theory, funded by the Carlsberg Foundation, Denmark.......We study social cost losses in Facility Location games, where n selfish agents install facilities over a network and connect to them, so as to forward their local demand (expressed by a non-negative weight per agent). Agents using the same facility share fairly its installation cost, but every...... networks we prove upper and lower bounds on PoS, while an O(ln n) upper bound implied by previous work is tight for non-metric networks. We also prove a constant upper bound for the SPoA of metric networks when strong equilibria exist. For the weighted game on general networks we prove existence of e...

  10. Radioimmunoassay of myosin heavy beta chains in human serum for the evaluation of the size of myocardial infarction: correlation with myocardial Tl-201 SPECT and cardiac angioscintigraphy

    International Nuclear Information System (INIS)

    Facello, A.; Gries, P.; Demangeat, C.; Brunot, B.; Roul, G.; Demangeat, J.L.; Moulichon, M.; Bareiss, P.; Sacrez, A.; Constantinesco, A.

    1990-01-01

    To determine the relationship between serum levels of myosin heavy beta chains assessed by an IRMA technique and other radionuclide and enzymatic parameters in the evaluation of the size of myocardial infarction, we studied 22 patients with acute myocardial infarction. Blood samples taken daily between 1st to 13th day of evolution allow the determination of peak and integral of myosine release that showed a good correlation (p [fr

  11. Error bounds from extra precise iterative refinement

    Energy Technology Data Exchange (ETDEWEB)

    Demmel, James; Hida, Yozo; Kahan, William; Li, Xiaoye S.; Mukherjee, Soni; Riedy, E. Jason

    2005-02-07

    We present the design and testing of an algorithm for iterative refinement of the solution of linear equations, where the residual is computed with extra precision. This algorithm was originally proposed in the 1960s [6, 22] as a means to compute very accurate solutions to all but the most ill-conditioned linear systems of equations. However two obstacles have until now prevented its adoption in standard subroutine libraries like LAPACK: (1) There was no standard way to access the higher precision arithmetic needed to compute residuals, and (2) it was unclear how to compute a reliable error bound for the computed solution. The completion of the new BLAS Technical Forum Standard [5] has recently removed the first obstacle. To overcome the second obstacle, we show how a single application of iterative refinement can be used to compute an error bound in any norm at small cost, and use this to compute both an error bound in the usual infinity norm, and a componentwise relative error bound. We report extensive test results on over 6.2 million matrices of dimension 5, 10, 100, and 1000. As long as a normwise (resp. componentwise) condition number computed by the algorithm is less than 1/max{l_brace}10,{radical}n{r_brace} {var_epsilon}{sub w}, the computed normwise (resp. componentwise) error bound is at most 2 max{l_brace}10,{radical}n{r_brace} {center_dot} {var_epsilon}{sub w}, and indeed bounds the true error. Here, n is the matrix dimension and w is single precision roundoff error. For worse conditioned problems, we get similarly small correct error bounds in over 89.4% of cases.

  12. Upper bounds on superpartner masses from upper bounds on the Higgs boson mass.

    Science.gov (United States)

    Cabrera, M E; Casas, J A; Delgado, A

    2012-01-13

    The LHC is putting bounds on the Higgs boson mass. In this Letter we use those bounds to constrain the minimal supersymmetric standard model (MSSM) parameter space using the fact that, in supersymmetry, the Higgs mass is a function of the masses of sparticles, and therefore an upper bound on the Higgs mass translates into an upper bound for the masses for superpartners. We show that, although current bounds do not constrain the MSSM parameter space from above, once the Higgs mass bound improves big regions of this parameter space will be excluded, putting upper bounds on supersymmetry (SUSY) masses. On the other hand, for the case of split-SUSY we show that, for moderate or large tanβ, the present bounds on the Higgs mass imply that the common mass for scalars cannot be greater than 10(11)  GeV. We show how these bounds will evolve as LHC continues to improve the limits on the Higgs mass.

  13. Direct photoaffinity labeling of gizzard myosin with [3H]uridine diphosphate places Glu185 of the heavy chain at the active site

    International Nuclear Information System (INIS)

    Garabedian, T.E.; Yount, R.G.

    1990-01-01

    The active site of chicken gizzard myosin was labeled by direct photoaffinity labeling with [ 3 H]UDP. [ 3 H] UDP was stably trapped at the active site by addition of vanadate (Vi) and Co 2+ . The extraordinary stability of the myosin.Co2+.[3H]UDP.Vi complex (t1/2 greater than 5 days at 0 degrees C) allowed it to be purified free of extraneous [ 3 H]UDP before irradiation began. Upon UV irradiation, greater than 60% of the trapped [ 3 H]UDP was photoincorporated into the active site. Only the 200-kDa heavy chain was labeled, confirming earlier results using [ 3 H]UTP. Extensive tryptic digestion of photolabeled myosin subfragment 1 followed by high performance liquid chromatography separations and removal of nucleotide phosphates by treatment with alkaline phosphatase allowed two labeled peptides to be isolated. Sequencing of the labeled peptides and radioactive counting showed that Glu185 was the residue labeled. Since UDP is a zero-length cross-linker, Glu185 is located at the purine-binding pocket of the active site of smooth myosin and adjacent to the glycine-rich loop which binds the polyphosphate portion of ATP. This Glu residue is conserved in smooth and nonmuscle myosins and is the same residue identified previously by [ 3 H]UTP photolabeling in Acanthamoeba myosin II

  14. Direct photoaffinity labeling of gizzard myosin with ( sup 3 H)uridine diphosphate places Glu185 of the heavy chain at the active site

    Energy Technology Data Exchange (ETDEWEB)

    Garabedian, T.E.; Yount, R.G. (Washington State Univ., Pullman (USA))

    1990-12-25

    The active site of chicken gizzard myosin was labeled by direct photoaffinity labeling with ({sup 3}H)UDP. ({sup 3}H) UDP was stably trapped at the active site by addition of vanadate (Vi) and Co{sup 2+}. The extraordinary stability of the myosin.Co2+.(3H)UDP.Vi complex (t1/2 greater than 5 days at 0{degrees}C) allowed it to be purified free of extraneous ({sup 3}H)UDP before irradiation began. Upon UV irradiation, greater than 60% of the trapped ({sup 3}H)UDP was photoincorporated into the active site. Only the 200-kDa heavy chain was labeled, confirming earlier results using ({sup 3}H)UTP. Extensive tryptic digestion of photolabeled myosin subfragment 1 followed by high performance liquid chromatography separations and removal of nucleotide phosphates by treatment with alkaline phosphatase allowed two labeled peptides to be isolated. Sequencing of the labeled peptides and radioactive counting showed that Glu185 was the residue labeled. Since UDP is a zero-length cross-linker, Glu185 is located at the purine-binding pocket of the active site of smooth myosin and adjacent to the glycine-rich loop which binds the polyphosphate portion of ATP. This Glu residue is conserved in smooth and nonmuscle myosins and is the same residue identified previously by ({sup 3}H)UTP photolabeling in Acanthamoeba myosin II.

  15. Tunable hybridization of Majorana bound states at the quantum spin Hall edge

    Science.gov (United States)

    Keidel, Felix; Burset, Pablo; Trauzettel, Björn

    2018-02-01

    Confinement at the helical edge of a topological insulator is possible in the presence of proximity-induced magnetic (F) or superconducting (S) order. The interplay of both phenomena leads to the formation of localized Majorana bound states (MBS) or likewise (under certain resonance conditions) the formation of ordinary Andreev bound states (ABS). We investigate the properties of bound states in junctions composed of alternating regions of F or S barriers. Interestingly, the direction of magnetization in F regions and the relative superconducting phase between S regions can be exploited to hybridize MBS or ABS at will. We show that the local properties of MBS translate into a particular nonlocal superconducting pairing amplitude. Remarkably, the symmetry of the pairing amplitude contains information about the nature of the bound state that it stems from. Hence this symmetry can in principle be used to distinguish MBS from ABS, owing to the strong connection between local density of states and nonlocal pairing in our setup.

  16. Bounds on poloidal kinetic energy in plane layer convection

    Science.gov (United States)

    Tilgner, A.

    2017-12-01

    A numerical method is presented that conveniently computes upper bounds on heat transport and poloidal energy in plane layer convection for infinite and finite Prandtl numbers. The bounds obtained for the heat transport coincide with earlier results. These bounds imply upper bounds for the poloidal energy, which follow directly from the definitions of dissipation and energy. The same constraints used for computing upper bounds on the heat transport lead to improved bounds for the poloidal energy.

  17. Continuum strong QCD: Confinement and dynamical chiral symmetry breaking

    International Nuclear Information System (INIS)

    Continuum strong QCD is the application of models and continuum quantum field theory to the study of phenomena in hadronic physics, which includes; e.g., the spectrum of QCD bound states and their interactions. Herein the author provides a Dyson-Schwinger equation perspective, focusing on qualitative aspects of confinement and dynamical chiral symmetry breaking in cold, sparse QCD, and also elucidating consequences of the axial-vector Ward-Takahashi identity and features of the heavy-quark limit

  18. Determining the impact of oxidation on the motility of single muscle-fibres expressing different myosin isoforms

    DEFF Research Database (Denmark)

    Spanos, Dimitrios; Li, M.; Baron, Caroline P.

    2013-01-01

    (motility speed) and force-generation capacity of specific MyHC isoforms. In the experimental procedure, single muscle fibres were split in different segments and each segment was exposed to a different concentration of hydrogen peroxide. Speed and force measurements were recorded and compared, to assess...... the effect of myosin oxidation on motility and force. The MyHC isoform expression in the single muscle fibre was subsequently determined on silver-stained gel SDS-PAGE. Preliminary results indicate a decrease of directionality and speed of the in-vitro motility as a result of an oxidative environment......, and the successful use of the assay in determining fibre-specific responses to oxidation. Subsequent analyses will focus on the location of protein modifications on the myosin molecule and on how these modifications induce changes in speed and force....

  19. Influence of long-term arotinolol treatment on myocardial mechanics and ventricular myosin isoenzymes in spontaneously hypertensive rats.

    Science.gov (United States)

    Takeda, N; Ohkubo, T; Iwai, T; Tanamura, A; Nagano, M

    1990-01-01

    Alterations in myocardial mechanics and left ventricular myosin isoenzymes by long-term treatment of hypertension with arotinolol were examined in spontaneously hypertensive rats. Approximately 20 mg/kg/day arotinolol was administered to 22-week-old male spontaneously hypertensive rats for 8-10 weeks. There was no significant difference in systolic blood pressure between arotinolol-treated and untreated rats. However, ventricular weight tended to decrease in the arotinolol-treated group, although not significantly. There were no significant differences in isometric developed tension and dT/dtmax of isolated left ventricular papillary muscles between the arotinolol-treated and untreated groups. The left ventricular myosin isoenzyme pattern, on the other hand, obtained by pyrophosphate gel electrophoresis, showed a significant shift toward VM-1 as a result of long-term arotinolol treatment.

  20. Comparison of new ELISA method with established SDS-PAGE method for determination of muscle myosin heavy chain isoforms

    Czech Academy of Sciences Publication Activity Database

    Říčný, Jan; Soukup, Tomáš

    2011-01-01

    Roč. 60, č. 6 (2011), s. 899-904 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA304/08/0256 Grant - others:EC(XE) LSH-CT-2004-511978 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscle fiber types * myosin heavy chains * SDS - PAGE * immunoreactions * thyroid hormones * ELISA Subject RIV: EA - Cell Biology Impact factor: 1.555, year: 2011

  1. Shared gene structures and clusters of mutually exclusive spliced exons within the metazoan muscle myosin heavy chain genes.

    Directory of Open Access Journals (Sweden)

    Martin Kollmar

    Full Text Available Multicellular animals possess two to three different types of muscle tissues. Striated muscles have considerable ultrastructural similarity and contain a core set of proteins including the muscle myosin heavy chain (Mhc protein. The ATPase activity of this myosin motor protein largely dictates muscle performance at the molecular level. Two different solutions to adjusting myosin properties to different muscle subtypes have been identified so far: Vertebrates and nematodes contain many independent differentially expressed Mhc genes while arthropods have single Mhc genes with clusters of mutually exclusive spliced exons (MXEs. The availability of hundreds of metazoan genomes now allowed us to study whether the ancient bilateria already contained MXEs, how MXE complexity subsequently evolved, and whether additional scenarios to control contractile properties in different muscles could be proposed, By reconstructing the Mhc genes from 116 metazoans we showed that all intron positions within the motor domain coding regions are conserved in all bilateria analysed. The last common ancestor of the bilateria already contained a cluster of MXEs coding for part of the loop-2 actin-binding sequence. Subsequently the protostomes and later the arthropods gained many further clusters while MXEs got completely lost independently in several branches (vertebrates and nematodes and species (for example the annelid Helobdella robusta and the salmon louse Lepeophtheirus salmonis. Several bilateria have been found to encode multiple Mhc genes that might all or in part contain clusters of MXEs. Notable examples are a cluster of six tandemly arrayed Mhc genes, of which two contain MXEs, in the owl limpet Lottia gigantea and four Mhc genes with three encoding MXEs in the predatory mite Metaseiulus occidentalis. Our analysis showed that similar solutions to provide different myosin isoforms (multiple genes or clusters of MXEs or both have independently been developed

  2. Enhancement of Force Generated by Individual Myosin Heads in Skinned Rabbit Psoas Muscle Fibers at Low Ionic Strength

    OpenAIRE

    Sugi, Haruo; Abe, Takahiro; Kobayashi, Takakazu; Chaen, Shigeru; Ohnuki, Yoshiki; Saeki, Yasutake; Sugiura, Seiryo

    2013-01-01

    Although evidence has been presented that, at low ionic strength, myosin heads in relaxed skeletal muscle fibers form linkages with actin filaments, the effect of low ionic strength on contraction characteristics of Ca(2+)-activated muscle fibers has not yet been studied in detail. To give information about the mechanism of muscle contraction, we have examined the effect of low ionic strength on the mechanical properties and the contraction characteristics of skinned rabbit psoas muscle fiber...

  3. Angiotensin II Facilitates Matrix Metalloproteinase-9-Mediated Myosin Light Chain Kinase Degradation in Pressure Overload-Induced Cardiac Hypertrophy

    Directory of Open Access Journals (Sweden)

    Shun Wang

    2017-12-01

    Full Text Available Background/Aims: Angiotensin II (Ang II has been shown to promote cardiac remodeling during the process of hypertrophy. Myosin light chain kinase (MLCK, a specific kinase for the phosphorylation of myosin light chain 2 (MLC2, plays an important role in regulating cardiac muscle contraction and hypertrophy. However, whether Ang II could facilitate cardiac hypertrophy by altering the expression of MLCK remains unclear. This study aimed to investigate this effect and the underlying mechanisms. Methods: Cardiac hypertrophy was induced via pressure overload in rats, which were then evaluated via histological and biochemical measurements and echocardiography. Angiotensin-converting enzyme inhibitor (ACEI was used to inhibit Ang II. Neonatal rat cardiomyocytes were stimulated with Ang II to induce hypertrophy and were treated with a matrix metalloproteinase 9 (MMP9 inhibitor. Myocyte hypertrophy was evaluated using immunofluorescence and qRT-PCR. Degradation of recombinant human MLCK by recombinant human MMP9 was tested using a cleavage assay. The expression levels of MLCK, MLC2, phospho-myosin light chain 2 (p-MLC2, myosin phosphatase 2 (MYPT2, and calmodulin (CaM were measured using western blotting. Results: ACEI improved cardiac function and remodeling and increased the levels of MLCK and p-MLC2 as well as reduced the expression of MMP9 in pressure overload-induced cardiac hypertrophy. Moreover, the MMP9 inhibitor alleviated myocyte hypertrophy and upregulated the levels of MLCK and p-MLC2 in Ang II-induced cardiomyocyte hypertrophy. Recombinant human MLCK was concentration- and time-dependently degraded by recombinant human MMP9 in vitro, and this process was prevented by the MMP9 inhibitor. Conclusion: Our results suggest that Ang II is involved in the degradation of MLCK in pressure overload-induced cardiac hypertrophy and that this process was mediated by MMP9.

  4. Independent specialisation of myosin II paralogues in muscle vs. non-muscle functions during early animal evolution: a ctenophore perspective.

    Science.gov (United States)

    Dayraud, Cyrielle; Alié, Alexandre; Jager, Muriel; Chang, Patrick; Le Guyader, Hervé; Manuel, Michaël; Quéinnec, Eric

    2012-07-02

    Myosin II (or Myosin Heavy Chain II, MHCII) is a family of molecular motors involved in the contractile activity of animal muscle cells but also in various other cellular processes in non-muscle cells. Previous phylogenetic analyses of bilaterian MHCII genes identified two main clades associated respectively with smooth/non-muscle cells (MHCIIa) and striated muscle cells (MHCIIb). Muscle cells are generally thought to have originated only once in ancient animal history, and decisive insights about their early evolution are expected to come from expression studies of Myosin II genes in the two non-bilaterian phyla that possess muscles, the Cnidaria and Ctenophora. We have uncovered three MHCII paralogues in the ctenophore species Pleurobrachia pileus. Phylogenetic analyses indicate that the MHCIIa / MHCIIb duplication is more ancient than the divergence between extant metazoan lineages. The ctenophore MHCIIa gene (PpiMHCIIa) has an expression pattern akin to that of "stem cell markers" (Piwi, Vasa…) and is expressed in proliferating cells. We identified two MHCIIb genes that originated from a ctenophore-specific duplication. PpiMHCIIb1 represents the exclusively muscular form of myosin II in ctenophore, while PpiMHCIIb2 is expressed in non-muscle cells of various types. In parallel, our phalloidin staining and TEM observations highlight the structural complexity of ctenophore musculature and emphasize the experimental interest of the ctenophore tentacle root, in which myogenesis is spatially ordered and strikingly similar to striated muscle formation in vertebrates. MHCIIa expression in putative stem cells/proliferating cells probably represents an ancestral trait, while specific involvement of some MHCIIa genes in smooth muscle fibres is a uniquely derived feature of the vertebrates. That one ctenophore MHCIIb paralogue (PpiMHCIIb2) has retained MHCIIa-like expression features furthermore suggests that muscular expression of the other paralogue, PpiMHCIIb1, was

  5. Independent specialisation of myosin II paralogues in muscle vs. non-muscle functions during early animal evolution: a ctenophore perspective

    Science.gov (United States)

    2012-01-01

    Background Myosin II (or Myosin Heavy Chain II, MHCII) is a family of molecular motors involved in the contractile activity of animal muscle cells but also in various other cellular processes in non-muscle cells. Previous phylogenetic analyses of bilaterian MHCII genes identified two main clades associated respectively with smooth/non-muscle cells (MHCIIa) and striated muscle cells (MHCIIb). Muscle cells are generally thought to have originated only once in ancient animal history, and decisive insights about their early evolution are expected to come from expression studies of Myosin II genes in the two non-bilaterian phyla that possess muscles, the Cnidaria and Ctenophora. Results We have uncovered three MHCII paralogues in the ctenophore species Pleurobrachia pileus. Phylogenetic analyses indicate that the MHCIIa / MHCIIb duplication is more ancient than the divergence between extant metazoan lineages. The ctenophore MHCIIa gene (PpiMHCIIa) has an expression pattern akin to that of "stem cell markers" (Piwi, Vasa…) and is expressed in proliferating cells. We identified two MHCIIb genes that originated from a ctenophore-specific duplication. PpiMHCIIb1 represents the exclusively muscular form of myosin II in ctenophore, while PpiMHCIIb2 is expressed in non-muscle cells of various types. In parallel, our phalloidin staining and TEM observations highlight the structural complexity of ctenophore musculature and emphasize the experimental interest of the ctenophore tentacle root, in which myogenesis is spatially ordered and strikingly similar to striated muscle formation in vertebrates. Conclusion MHCIIa expression in putative stem cells/proliferating cells probably represents an ancestral trait, while specific involvement of some MHCIIa genes in smooth muscle fibres is a uniquely derived feature of the vertebrates. That one ctenophore MHCIIb paralogue (PpiMHCIIb2) has retained MHCIIa-like expression features furthermore suggests that muscular expression of the

  6. Independent specialisation of myosin II paralogues in muscle vs. non-muscle functions during early animal evolution: a ctenophore perspective

    Directory of Open Access Journals (Sweden)

    Dayraud Cyrielle

    2012-07-01

    Full Text Available Abstract Background Myosin II (or Myosin Heavy Chain II, MHCII is a family of molecular motors involved in the contractile activity of animal muscle cells but also in various other cellular processes in non-muscle cells. Previous phylogenetic analyses of bilaterian MHCII genes identified two main clades associated respectively with smooth/non-muscle cells (MHCIIa and striated muscle cells (MHCIIb. Muscle cells are generally thought to have originated only once in ancient animal history, and decisive insights about their early evolution are expected to come from expression studies of Myosin II genes in the two non-bilaterian phyla that possess muscles, the Cnidaria and Ctenophora. Results We have uncovered three MHCII paralogues in the ctenophore species Pleurobrachia pileus. Phylogenetic analyses indicate that the MHCIIa / MHCIIb duplication is more ancient than the divergence between extant metazoan lineages. The ctenophore MHCIIa gene (PpiMHCIIa has an expression pattern akin to that of "stem cell markers" (Piwi, Vasa… and is expressed in proliferating cells. We identified two MHCIIb genes that originated from a ctenophore-specific duplication. PpiMHCIIb1 represents the exclusively muscular form of myosin II in ctenophore, while PpiMHCIIb2 is expressed in non-muscle cells of various types. In parallel, our phalloidin staining and TEM observations highlight the structural complexity of ctenophore musculature and emphasize the experimental interest of the ctenophore tentacle root, in which myogenesis is spatially ordered and strikingly similar to striated muscle formation in vertebrates. Conclusion MHCIIa expression in putative stem cells/proliferating cells probably represents an ancestral trait, while specific involvement of some MHCIIa genes in smooth muscle fibres is a uniquely derived feature of the vertebrates. That one ctenophore MHCIIb paralogue (PpiMHCIIb2 has retained MHCIIa-like expression features furthermore suggests that muscular

  7. Contractile properties, fiber types, and myosin isoforms in fast and slow muscles of hyperactive Japanese waltzing mice

    Czech Academy of Sciences Publication Activity Database

    Asmussen, G.; Schmalbruch, I.; Soukup, Tomáš; Pette, D.

    2003-01-01

    Roč. 184, č. 2 (2003), s. 758-766 ISSN 0014-4886 R&D Projects: GA ČR GA304/00/1653 Grant - others:Deutsche Forschungsgemeinschaft(DE) -; Sonderforschungsbereich(DE) 156; Schwerpunkt Muskelforschung(DE) As 74/1-2 Institutional research plan: CEZ:AV0Z5011922 Keywords : Japanese waltzing mouse * muscle contraction * myosin isoforms Subject RIV: ED - Physiology Impact factor: 3.676, year: 2003

  8. Better Bounds on Online Unit Clustering

    Science.gov (United States)

    Ehmsen, Martin R.; Larsen, Kim S.

    Unit Clustering is the problem of dividing a set of points from a metric space into a minimal number of subsets such that the points in each subset are enclosable by a unit ball. We continue work initiated by Chan and Zarrabi-Zadeh on determining the competitive ratio of the online version of this problem. For the one-dimensional case, we develop a deterministic algorithm, improving the best known upper bound of 7/4 by Epstein and van Stee to 5/3. This narrows the gap to the best known lower bound of 8/5 to only 1/15. Our algorithm automatically leads to improvements in all higher dimensions as well. Finally, we strengthen the deterministic lower bound in two dimensions and higher from 2 to 13/6.

  9. Experimental bounds on sterile neutrino mixing angles

    CERN Document Server

    Ruchayskiy, Oleg

    2012-01-01

    We derive bounds on the mixing between the left-chiral ("active") and the right-chiral ("sterile") neutrinos, provided from the combination of neutrino oscillation data and direct experimental searches for sterile neutrinos. We demonstrate that the mixing of sterile neutrinos with any flavour can be significantly suppressed, provided that the angle theta_13 is non-zero. This means that the lower bounds on sterile neutrino lifetime, coming from the negative results of direct experimental searches can be relaxed (by as much as the order of magnitude at some masses). We also demonstrate that the results of the negative searches of sterile neutrinos with PS191 and CHARM experiments are not applicable directly to the see-saw models. The reinterpretation of these results provides up to the order of magnitude stronger bounds on sterile neutrino lifetime than previously discussed in the literature. We discuss the implications of our results for the Neutrino Minimal Standard Model (the NuMSM).

  10. Bounded Gaps between Products of Special Primes

    Directory of Open Access Journals (Sweden)

    Ping Ngai Chung

    2014-03-01

    Full Text Available In their breakthrough paper in 2006, Goldston, Graham, Pintz and Yıldırım proved several results about bounded gaps between products of two distinct primes. Frank Thorne expanded on this result, proving bounded gaps in the set of square-free numbers with r prime factors for any r ≥ 2, all of which are in a given set of primes. His results yield applications to the divisibility of class numbers and the triviality of ranks of elliptic curves. In this paper, we relax the condition on the number of prime factors and prove an analogous result using a modified approach. We then revisit Thorne’s applications and give a better bound in each case.

  11. Myosin light chain kinase knockout improves gut barrier function and confers a survival advantage in polymicrobial sepsis.

    Science.gov (United States)

    Lorentz, C Adam; Liang, Zhe; Meng, Mei; Chen, Ching-Wen; Yoseph, Benyam P; Breed, Elise R; Mittal, Rohit; Klingensmith, Nathan J; Farris, Alton B; Burd, Eileen M; Koval, Michael; Ford, Mandy L; Coopersmith, Craig M

    2017-06-07

    Sepsis-induced intestinal hyperpermeability is mediated by disruption of the epithelial tight junction, which is closely associated with the peri-junctional actin-myosin ring. Myosin light chain kinase (MLCK) phosphorylates the myosin regulatory light chain, resulting in increased permeability. The purpose of this study was to determine whether genetic deletion of MLCK would alter gut barrier function and survival from sepsis. MLCK -/- and wild type (WT) mice were subjected to cecal ligation and puncture and assayed for both survival and mechanistic studies. Survival was significantly increased in MLCK -/- mice (95% vs. 24%, p<0.0001). Intestinal permeability increased in septic WT mice compared to unmanipulated mice. In contrast, permeability in septic MLCK -/- mice was similar to that seen in unmanipulated animals. Improved gut barrier function in MLCK -/- mice was associated with increases in the tight junction mediators ZO-1 and claudin 15 without alterations in claudin 1, 2, 3, 4, 5, 7, 8, 13, occludin or JAM-A. Other components of intestinal integrity (apoptosis, proliferation and villus length) were unaffected by MLCK deletion as were local peritoneal inflammation and distant lung injury. Systemic IL-10 was decreased greater than 10-fold in MLCK -/- mice; however, survival was similar between septic MLCK -/- mice given exogenous IL-10 or vehicle. These data demonstrate that deletion of MLCK improves survival following sepsis, associated with normalization of intestinal permeability and selected tight junction proteins.

  12. Age- and Activity-Related Differences in the Abundance of Myosin Essential and Regulatory Light Chains in Human Muscle

    Directory of Open Access Journals (Sweden)

    James N. Cobley

    2016-04-01

    Full Text Available Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry are labor-intensive and ill-suited to multixplex analysis, i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM. We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageing per se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping.

  13. Myosin Light Chain Kinase (MLCK Gene Influences Exercise Induced Muscle Damage during a Competitive Marathon.

    Directory of Open Access Journals (Sweden)

    Juan Del Coso

    Full Text Available Myosin light chain kinase (MLCK phosphorylates the regulatory light chain (RLC of myosin producing increases in force development during skeletal muscle contraction. It has been suggested that MLCK gene polymorphisms might alter RLC phosphorylation thereby decreasing the ability to produce force and to resist strain during voluntary muscle contractions. Thus, the genetic variations in the MLCK gene might predispose some individuals to higher values of muscle damage during exercise, especially during endurance competitions. The aim of this investigation was to determine the influence of MLCK genetic variants on exercise-induced muscle damage produced during a marathon. Sixty-seven experienced runners competed in a marathon race. The MLCK genotype (C37885A of these marathoners was determined. Before and after the race, a sample of venous blood was obtained to assess changes in serum myoglobin concentrations and leg muscle power changes were measured during a countermovement jump. Self-reported leg muscle pain and fatigue were determined by questionnaires. A total of 59 marathoners (88.1% were CC homozygotes and 8 marathoners (11.9% were CA heterozygotes. The two groups of participants completed the race with a similar time (228 ± 33 vs 234 ± 39 min; P = 0.30 and similar self-reported values for fatigue (15 ± 2 vs 16 ± 2 A.U.; P = 0.21 and lower-limb muscle pain (6.2 ± 1.7 vs 6.6 ± 1.8 cm; P = 0.29. However, CC marathoners presented higher serum myoglobin concentrations (739 ± 792 vs 348 ± 144 μg·mL-1; P = 0.03 and greater pre-to-post- race leg muscle power reduction (-32.7 ± 15.7 vs -21.2 ± 21.6%; P = 0.05 than CA marathoners. CA heterozygotes for MLCK C37885A might present higher exercise-induced muscle damage after a marathon competition than CC counterparts.

  14. Career Development and Personal Functioning Differences between Work-Bound and Non-Work Bound Students

    Science.gov (United States)

    Creed, Peter A.; Patton, Wendy; Hood, Michelle

    2010-01-01

    We surveyed 506 Australian high school students on career development (exploration, planning, job-knowledge, decision-making, indecision), personal functioning (well-being, self-esteem, life satisfaction, school satisfaction) and control variables (parent education, school achievement), and tested differences among work-bound, college-bound and…

  15. Explicit strong stability preserving multistep Runge–Kutta methods

    KAUST Repository

    Bresten, Christopher

    2015-10-15

    High-order spatial discretizations of hyperbolic PDEs are often designed to have strong stability properties, such as monotonicity. We study explicit multistep Runge-Kutta strong stability preserving (SSP) time integration methods for use with such discretizations. We prove an upper bound on the SSP coefficient of explicit multistep Runge-Kutta methods of order two and above. Numerical optimization is used to find optimized explicit methods of up to five steps, eight stages, and tenth order. These methods are tested on the linear advection and nonlinear Buckley-Leverett equations, and the results for the observed total variation diminishing and/or positivity preserving time-step are presented.

  16. Quantum theory of strong-field frustrated tunneling

    Science.gov (United States)

    Popruzhenko, S. V.

    2018-01-01

    We show how the strong-field approximation, widely used for description of multiphoton and tunneling ionization, can be extended to analyse the excitation of bound states in intense low-frequency laser pulses. The proposed theory is based on the formalism of quantum trajectories and fills the gap between the numerical solution of the time-dependent Schrödinger equation and classical simulations. In particular, it allows identifying non-adiabatic and interference effects in strong-field excitation of Rydberg states.

  17. O{sup -} bound small polarons in oxide materials

    Energy Technology Data Exchange (ETDEWEB)

    Schirmer, O F [Department of Physics, University of Osnabrueck, D-49076 Osnabrueck (Germany)

    2006-11-01

    Holes bound to acceptor defects in oxide crystals are often localized by lattice distortion at just one of the equivalent oxygen ligands of the defect. Such holes thus form small polarons in symmetric clusters of a few oxygen ions. An overview on mainly the optical manifestations of those clusters is given. The article is essentially divided into two parts: the first one covers the basic features of the phenomena and their explanations, exemplified by several paradigmatic defects; in the second part numerous oxide materials are presented which exhibit bound small polaron optical properties. The first part starts with summaries on the production of bound hole polarons and the identification of their structure. It is demonstrated why they show strong, wide absorption bands, usually visible, based on polaron stabilization energies of typically 1 eV. The basic absorption process is detailed with a fictitious two-well system. Clusters with four, six and twelve equivalent ions are realized in various oxide compounds. In these cases several degenerate optically excited polaron states occur, leading to characteristic final state resonance splittings. The peak energies of the absorption bands as well as the sign of the transfer energy depend on the topology of the clusters. A special section is devoted to the distinction between interpolaron and intrapolaron optical transitions. The latter are usually comparatively weak. The oxide compounds exhibiting bound hole small polaron absorptions include the alkaline earth oxides (e.g. MgO), BeO and ZnO, the perovskites BaTiO{sub 3} and KTaO{sub 3}, quartz, the sillenites (e.g. Bi{sub 12}TiO{sub 20}), Al{sub 2}O{sub 3}, LiNbO{sub 3}, topaz and various other materials. There are indications that the magnetic crystals NiO, doped with Li, and LaMnO{sub 3}, doped with Sr, also show optical features caused by bound hole polarons. Beyond being elementary paradigms for the properties of small polarons in general, the defect species treated

  18. Causality, joint measurement and Tsirelson's bound

    International Nuclear Information System (INIS)

    Choudhary, Sujit K.; Kar, Guruprasad; Kunkri, Samir; Rahaman, Ramij

    2007-01-01

    Tsirelson showed that 2√(2) is the maximum value that CHSH expression can take for quantum correlations [B.S. Tsirelson, Lett. Math. Phys. 4 (1980) 93]. This bound simply follows from the algebra of observables. Recently by exploiting the physical structure of quantum mechanics like unitarity and linearity, Buhrman and Massar [H. Buhrman, S. Massar, Phys. Rev. A 72 (2005) 052103] have established that violation of Tsirelson's bound in quantum mechanics will imply signalling. We prove the same with the help of realistic joint measurement in quantum mechanics and a Bell's inequality which has been derived under the assumption of existence of joint measurement and no signalling condition

  19. G-frames with bounded linear operators

    OpenAIRE

    Xiao, Xiang-chun; Zhu, Yu-can; Shu, Zhi-biao; Ding, Ming-ling

    2015-01-01

    In this paper, we introduce the more general g-frame which is called a $K$-g-frame by combining a g-frame with a bounded linear operator $K$ in a Hilbert space. We give several equivalent characterizations for $K$-g-frames and discuss the stability of perturbation for $K$-g-frames. We also investigate the relationship between a $K$-g-frame and the range of the bounded linear operator $K$. In the end, we give two sufficient conditions for the remainder of a $K$-g-frame after an erasure to stil...

  20. Quantum Kolmogorov complexity and bounded quantum memory

    Science.gov (United States)

    Miyadera, Takayuki

    2011-04-01

    The effect of bounded quantum memory in a primitive information protocol has been examined using the quantum Kolmogorov complexity as a measure of information. We employed a toy two-party protocol in which Bob, by using a bounded quantum memory and an unbounded classical memory, estimates a message that was encoded in qubits by Alice in one of the bases X or Z. Our theorem gave a nontrivial effect of the memory boundedness. In addition, a generalization of the uncertainty principle in the presence of quantum memory has been obtained.

  1. Quantum Kolmogorov complexity and bounded quantum memory

    International Nuclear Information System (INIS)

    Miyadera, Takayuki

    2011-01-01

    The effect of bounded quantum memory in a primitive information protocol has been examined using the quantum Kolmogorov complexity as a measure of information. We employed a toy two-party protocol in which Bob, by using a bounded quantum memory and an unbounded classical memory, estimates a message that was encoded in qubits by Alice in one of the bases X or Z. Our theorem gave a nontrivial effect of the memory boundedness. In addition, a generalization of the uncertainty principle in the presence of quantum memory has been obtained.

  2. Quantum Kolmogorov Complexity and Bounded Quantum Memory

    OpenAIRE

    Miyadera, Takayuki

    2011-01-01

    In this study, the effect of bounded quantum memory in a primitive information protocol has been examined using the quantum Kolmogorov complexity as a measure of information. We employed a toy two-party protocol in which Bob by using a bounded quantum memory and an unbounded classical memory estimates a message that was encoded in qubits by Alice in one of the bases X or Z. Our theorem gave a nontrivial effect of the memory boundedness. In addition, a generalization of the uncertainty princip...

  3. Violation of Energy Bounds in Designer Gravity

    CERN Document Server

    Hertog, T

    2007-01-01

    We continue our study of the stability of designer gravity theories, where one considers anti-de Sitter gravity coupled to certain tachyonic scalars with boundary conditions defined by a smooth function W. It has recently been argued there is a lower bound on the conserved energy in terms of the global minimum of W, if the scalar potential arises from a superpotential P and the scalar reaches an extremum of P at infinity. We show, however, there are superpotentials for which these bounds do not hold.

  4. Bound states in curved quantum waveguides

    International Nuclear Information System (INIS)

    Exner, P.; Seba, P.

    1987-01-01

    We study free quantum particle living on a curved planar strip Ω of a fixed width d with Dirichlet boundary conditions. It can serve as a model for electrons in thin films on a cylindrical-type substrate, or in a curved quantum wire. Assuming that the boundary of Ω is infinitely smooth and its curvature decays fast enough at infinity, we prove that a bound state with energy below the first transversal mode exists for all sufficiently small d. A lower bound on the critical width is obtained using the Birman-Schwinger technique. (orig.)

  5. Finding Maximal Pairs with Bounded Gap

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Lyngsø, Rune B.; Pedersen, Christian N. S.

    1999-01-01

    . In this paper we present methods for finding all maximal pairs under various constraints on the gap. In a string of length n we can find all maximal pairs with gap in an upper and lower bounded interval in time O(n log n+z) where z is the number of reported pairs. If the upper bound is removed the time reduces...... to O(n+z). Since a tandem repeat is a pair where the gap is zero, our methods can be seen as a generalization of finding tandem repeats. The running time of our methods equals the running time of well known methods for finding tandem repeats....

  6. Quantum electrodynamics of strong fields

    International Nuclear Information System (INIS)

    Greiner, W.

    1983-01-01

    Quantum Electrodynamics of Strong Fields provides a broad survey of the theoretical and experimental work accomplished, presenting papers by a group of international researchers who have made significant contributions to this developing area. Exploring the quantum theory of strong fields, the volume focuses on the phase transition to a charged vacuum in strong electric fields. The contributors also discuss such related topics as QED at short distances, precision tests of QED, nonperturbative QCD and confinement, pion condensation, and strong gravitational fields In addition, the volume features a historical paper on the roots of quantum field theory in the history of quantum physics by noted researcher Friedrich Hund

  7. Robustness of Majorana bound states in the short-junction limit

    NARCIS (Netherlands)

    Sticlet, D.C.; Nijholt, B.; Akhmerov, A.R.

    2017-01-01

    We study the effects of strong coupling between a superconductor and a semiconductor nanowire on the creation of the Majorana bound states, when the quasiparticle dwell time in the normal part of the nanowire is much shorter than the inverse superconducting gap. This "short-junction" limit is

  8. Vascular O-GlcNAcylation augments reactivity to constrictor stimuli by prolonging phosphorylated levels of the myosin light chain

    Energy Technology Data Exchange (ETDEWEB)

    Lima, V.V. [Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso, Barra do Garças, MT (Brazil); Lobato, N.S.; Filgueira, F.P. [Curso de Medicina, Setor de Fisiologia Humana, Universidade Federal de Goiás, Jataí, GO (Brazil); Webb, R.C. [Department of Physiology, Georgia Regents University, Augusta, GA (United States); Tostes, R.C. [Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Giachini, F.R. [Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso, Barra do Garças, MT (Brazil)

    2014-08-15

    O-GlcNAcylation is a modification that alters the function of numerous proteins. We hypothesized that augmented O-GlcNAcylation levels enhance myosin light chain kinase (MLCK) and reduce myosin light chain phosphatase (MLCP) activity, leading to increased vascular contractile responsiveness. The vascular responses were measured by isometric force displacement. Thoracic aorta and vascular smooth muscle cells (VSMCs) from rats were incubated with vehicle or with PugNAc, which increases O-GlcNAcylation. In addition, we determined whether proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation. PugNAc enhanced phenylephrine (PE) responses in rat aortas (maximal effect, 14.2±2 vs 7.9±1 mN for vehicle, n=7). Treatment with an MLCP inhibitor (calyculin A) augmented vascular responses to PE (13.4±2 mN) and abolished the differences in PE-response between the groups. The effect of PugNAc was not observed when vessels were preincubated with ML-9, an MLCK inhibitor (7.3±2 vs 7.5±2 mN for vehicle, n=5). Furthermore, our data showed that differences in the PE-induced contractile response between the groups were abolished by the activator of AMP-activated protein kinase (AICAR; 6.1±2 vs 7.4±2 mN for vehicle, n=5). PugNAc increased phosphorylation of myosin phosphatase target subunit 1 (MYPT-1) and protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17), which are involved in RhoA/Rho-kinase-mediated inhibition of myosin phosphatase activity. PugNAc incubation produced a time-dependent increase in vascular phosphorylation of myosin light chain and decreased phosphorylation levels of AMP-activated protein kinase, which decreased the affinity of MLCK for Ca{sup 2+}/calmodulin. Our data suggest that proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation, favoring vascular contraction.

  9. Enhancement of force generated by individual myosin heads in skinned rabbit psoas muscle fibers at low ionic strength.

    Science.gov (United States)

    Sugi, Haruo; Abe, Takahiro; Kobayashi, Takakazu; Chaen, Shigeru; Ohnuki, Yoshiki; Saeki, Yasutake; Sugiura, Seiryo

    2013-01-01

    Although evidence has been presented that, at low ionic strength, myosin heads in relaxed skeletal muscle fibers form linkages with actin filaments, the effect of low ionic strength on contraction characteristics of Ca(2+)-activated muscle fibers has not yet been studied in detail. To give information about the mechanism of muscle contraction, we have examined the effect of low ionic strength on the mechanical properties and the contraction characteristics of skinned rabbit psoas muscle fibers in both relaxed and maximally Ca(2+)-activated states. By progressively decreasing KCl concentration from 125 mM to 0 mM (corresponding to a decrease in ionic strength μ from 170 mM to 50 mM), relaxed fibers showed changes in mechanical response to sinusoidal length changes and ramp stretches, which are consistent with the idea of actin-myosin linkage formation at low ionic strength. In maximally Ca(2+)-activated fibers, on the other hand, the maximum isometric force increased about twofold by reducing KCl concentration from 125 to 0 mM. Unexpectedly, determination of the force-velocity curves indicated that, the maximum unloaded shortening velocity Vmax, remained unchanged at low ionic strength. This finding indicates that the actin-myosin linkages, which has been detected in relaxed fibers at low ionic strength, are broken quickly on Ca(2+) activation, so that the linkages in relaxed fibers no longer provide any internal resistance against fiber shortening. The force-velocity curves, obtained at various levels of steady Ca(2+)-activated isometric force, were found to be identical if they are normalized with respect to the maximum isometric force. The MgATPase activity of muscle fibers during isometric force generation was found not to change appreciably at low ionic strength despite the two-fold increase in Ca(2+)-activated isometric force. These results can be explained in terms of enhancement of force generated by individual myosin heads, but not by any changes in

  10. Enhancement of force generated by individual myosin heads in skinned rabbit psoas muscle fibers at low ionic strength.

    Directory of Open Access Journals (Sweden)

    Haruo Sugi

    Full Text Available Although evidence has been presented that, at low ionic strength, myosin heads in relaxed skeletal muscle fibers form linkages with actin filaments, the effect of low ionic strength on contraction characteristics of Ca(2+-activated muscle fibers has not yet been studied in detail. To give information about the mechanism of muscle contraction, we have examined the effect of low ionic strength on the mechanical properties and the contraction characteristics of skinned rabbit psoas muscle fibers in both relaxed and maximally Ca(2+-activated states. By progressively decreasing KCl concentration from 125 mM to 0 mM (corresponding to a decrease in ionic strength μ from 170 mM to 50 mM, relaxed fibers showed changes in mechanical response to sinusoidal length changes and ramp stretches, which are consistent with the idea of actin-myosin linkage formation at low ionic strength. In maximally Ca(2+-activated fibers, on the other hand, the maximum isometric force increased about twofold by reducing KCl concentration from 125 to 0 mM. Unexpectedly, determination of the force-velocity curves indicated that, the maximum unloaded shortening velocity Vmax, remained unchanged at low ionic strength. This finding indicates that the actin-myosin linkages, which has been detected in relaxed fibers at low ionic strength, are broken quickly on Ca(2+ activation, so that the linkages in relaxed fibers no longer provide any internal resistance against fiber shortening. The force-velocity curves, obtained at various levels of steady Ca(2+-activated isometric force, were found to be identical if they are normalized with respect to the maximum isometric force. The MgATPase activity of muscle fibers during isometric force generation was found not to change appreciably at low ionic strength despite the two-fold increase in Ca(2+-activated isometric force. These results can be explained in terms of enhancement of force generated by individual myosin heads, but not by any

  11. Vascular O-GlcNAcylation augments reactivity to constrictor stimuli by prolonging phosphorylated levels of the myosin light chain

    International Nuclear Information System (INIS)

    Lima, V.V.; Lobato, N.S.; Filgueira, F.P.; Webb, R.C.; Tostes, R.C.; Giachini, F.R.

    2014-01-01

    O-GlcNAcylation is a modification that alters the function of numerous proteins. We hypothesized that augmented O-GlcNAcylation levels enhance myosin light chain kinase (MLCK) and reduce myosin light chain phosphatase (MLCP) activity, leading to increased vascular contractile responsiveness. The vascular responses were measured by isometric force displacement. Thoracic aorta and vascular smooth muscle cells (VSMCs) from rats were incubated with vehicle or with PugNAc, which increases O-GlcNAcylation. In addition, we determined whether proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation. PugNAc enhanced phenylephrine (PE) responses in rat aortas (maximal effect, 14.2±2 vs 7.9±1 mN for vehicle, n=7). Treatment with an MLCP inhibitor (calyculin A) augmented vascular responses to PE (13.4±2 mN) and abolished the differences in PE-response between the groups. The effect of PugNAc was not observed when vessels were preincubated with ML-9, an MLCK inhibitor (7.3±2 vs 7.5±2 mN for vehicle, n=5). Furthermore, our data showed that differences in the PE-induced contractile response between the groups were abolished by the activator of AMP-activated protein kinase (AICAR; 6.1±2 vs 7.4±2 mN for vehicle, n=5). PugNAc increased phosphorylation of myosin phosphatase target subunit 1 (MYPT-1) and protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17), which are involved in RhoA/Rho-kinase-mediated inhibition of myosin phosphatase activity. PugNAc incubation produced a time-dependent increase in vascular phosphorylation of myosin light chain and decreased phosphorylation levels of AMP-activated protein kinase, which decreased the affinity of MLCK for Ca 2+ /calmodulin. Our data suggest that proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation, favoring vascular contraction

  12. The effect of the substitution of D{sub 2}O for H{sub 2}O on the degradation of myosin {beta} in solution by heat and by {sup 60}Co {gamma} radiation (1962); Effet de la substitution de D{sub 2}O a H{sub 2}O sur l'alteration de la Myosine B en solution par la chaleur et par les rayons {gamma} du {sup 60}CO (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Pinset-Harstrom, I.; Fritsch, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    (1) Alterations of myosin B produced by heat or irradiation are shown to be qualitatively identical as demonstrated by analytical centrifugation. (2) A considerable isotope effect was demonstrated using 75 per cent D{sub 2}O in the solvent. The sensitivity of myosin B to heat and irradiation is discussed in the light of this isotope effect. (3) Polymers appearing upon heat treatment of myosin B seem to be of a very different nature than the polymers occurring alter a similar treatment upon myosin A. Polymers obtained from myosin B can be depolymerized by ATP and they appear in a much narrower temperature range than myosin A polymers. This fact indicates a considerable difference in the activation enthalpies in the two reactions. (authors) [French] (1) Cette etude montre que les alterations de la myosine B provoquees par la chaleur et par l'irradiation aux rayons {gamma} sont - telles qu'elles apparaissent a l'ultracentrifugation analytique - qualitativement semblables. (2) Nous avons observe un effet isotopique considerable de la presence de 75 pour cent de D{sub 2}O dans le solvant sur la sensibilite de la myosine B envers ces deux agents, et nous avons presente une tentative d'explication de ce fait. (3) Les polymeres qui apparaissent apres un traitement par la chaleur de la myosine semblent etre d'une nature tres differente des polymeres que l'on voit apparaitre apres un traitement identique de la myosine A. Ceux obtenus a partir de le myosine B sont depolymerisables par l'intermediaire de l'ATP et apparaissent dans une zone de temperature beaucoup plus etroite que celles de la myosine A. Ce dernier fait indique une difference considerable de l'enthalpie d'activation des deux reactions. (auteurs)

  13. Molecular mechanisms of non-transferrin-bound and transferring-bound iron uptake in primary hippocampal neurons.

    Science.gov (United States)

    Ji, Changyi; Kosman, Daniel J

    2015-06-01

    The molecular mechanisms of iron trafficking in neurons have not been elucidated. In this study, we characterized the expression and localization of ferrous iron transporters Zip8, Zip14 and divalent metal transporter 1 (DMT1), and ferrireductases Steap2 and stromal cell-derived receptor 2 in primary rat hippocampal neurons. Steap2 and Zip8 partially co-localize, indicating these two proteins may function in Fe(3+) reduction prior to Fe(2+) permeation. Zip8, DMT1, and Steap2 co-localize with the transferrin receptor/transferrin complex, suggesting they may be involved in transferrin receptor/transferrin-mediated iron assimilation. In brain interstitial fluid, transferring-bound iron (TBI) and non-transferrin-bound iron (NTBI) exist as potential iron sources. Primary hippocampal neurons exhibit significant iron uptake from TBI (Transferrin-(59) Fe(3+)) and NTBI, whether presented as (59) Fe(2+) -citrate or (59) Fe(3+) -citrate; reductase-independent (59) Fe(2+) uptake was the most efficient uptake pathway of the three. Kinetic analysis of Zn(2+) inhibition of Fe(2+) uptake indicated that DMT1 plays only a minor role in the uptake of NTBI. In contrast, localization and knockdown data indicate that Zip8 makes a major contribution. Data suggest also that cell accumulation of (59) Fe from TBI relies at least in part on an endocytosis-independent pathway. These data suggest that Zip8 and Steap2 play a major role in iron accumulation from NTBI and TBI by hippocampal neurons. Analysis of the expression and localization of known iron uptake transporters demonstrated that Zip8 makes a major contribution to iron accumulation in primary cultures of rat embryonic hippocampal neurons. These cells exhibit uptake pathways for ferrous and ferric iron (non-transferrin-bound iron, NTBI in figure) and for transferrin-bound iron; the ferrireductases Steap2 and SDR2 support the uptake of ferric iron substrates. Zip8 and Steap2 are strongly expressed in the plasma membrane of both soma

  14. Hypoxia favors myosin heavy chain beta gene expression in an Hif-1alpha-dependent manner.

    Science.gov (United States)

    Binó, Lucia; Procházková, Jiřina; Radaszkiewicz, Katarzyna Anna; Kučera, Jan; Kudová, Jana; Pacherník, Jiří; Kubala, Lukáš

    2017-10-13

    The potentiation of the naturally limited regenerative capacity of the heart is dependent on an understanding of the mechanisms that are activated in response to pathological conditions such as hypoxia. Under these conditions, the expression of genes suggested to support cardiomyocyte survival and heart adaptation is triggered. Particularly important are changes in the expression of myosin heavy chain (MHC) isoforms. We propose here that alterations in the expression profiles of MHC genes are induced in response to hypoxia and are primarily mediated by hypoxia inducible factor (HIF). In in vitro models of mouse embryonic stem cell-derived cardiomyocytes, we showed that hypoxia (1% O 2 ) or the pharmacological stabilization of HIFs significantly increased MHCbeta ( Myh7 ) gene expression. The key role of HIF-1alpha is supported by the absence of these effects in HIF-1alpha-deficient cells, even in the presence of HIF-2alpha. Interestingly, ChIP analysis did not confirm the direct interaction of HIF-1alpha with putative HIF response elements predicted in the MHCalpha and beta encoding DNA region. Further analyses showed the significant effect of the mTOR signaling inhibitor rapamycin in inducing Myh7 expression and a hypoxia-triggered reduction in the levels of antisense RNA transcripts associated with the Myh7 gene locus. Overall, the recognized and important role of HIF in the regulation of heart regenerative processes could be highly significant for the development of novel therapeutic interventions in heart failure.

  15. Aspergillus myosin-V supports polarized growth in the absence of microtubule-based transport.

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    Full Text Available In the filamentous fungus Aspergillus nidulans, both microtubules and actin filaments are important for polarized growth at the hyphal tip. Less clear is how different microtubule-based and actin-based motors work together to support this growth. Here we examined the role of myosin-V (MYOV in hyphal growth. MYOV-depleted cells form elongated hyphae, but the rate of hyphal elongation is significantly reduced. In addition, although wild type cells without microtubules still undergo polarized growth, microtubule disassembly abolishes polarized growth in MYOV-depleted cells. Thus, MYOV is essential for polarized growth in the absence of microtubules. Moreover, while a triple kinesin null mutant lacking kinesin-1 (KINA and two kinesin-3s (UNCA and UNCB undergoes hyphal elongation and forms a colony, depleting MYOV in this triple mutant results in lethality due to a severe defect in polarized growth. These results argue that MYOV, through its ability to transport secretory cargo, can support a significant amount of polarized hyphal tip growth in the absence of any microtubule-based transport. Finally, our genetic analyses also indicate that KINA (kinesin-1 rather than UNCA (kinesin-3 is the major kinesin motor that supports polarized growth in the absence of MYOV.

  16. Oxidation-induced unfolding facilitates Myosin cross-linking in myofibrillar protein by microbial transglutaminase.

    Science.gov (United States)

    Li, Chunqiang; Xiong, Youling L; Chen, Jie

    2012-08-15

    Myofibrillar protein from pork Longissimus muscle was oxidatively stressed for 2 and 24 h at 4 °C with mixed 10 μM FeCl(3)/100 μM ascorbic acid/1, 5, or 10 mM H(2)O(2) (which produces hydroxyl radicals) and then treated with microbial transglutaminase (MTG) (E:S = 1:20) for 2 h at 4 °C. Oxidation induced significant protein structural changes (P activity, elevated Ca-ATPase activity, increased carbonyl and disulfide contents, and reduced conformational stability, all in a H(2)O(2) dose-dependent manner. The structural alterations, notably with mild oxidation, led to stronger MTG catalysis. More substantial amine reductions (19.8-27.6%) at 1 mM H(2)O(2) occurred as compared to 11.6% in nonoxidized samples (P < 0.05) after MTG treatment. This coincided with more pronounced losses of myosin in oxidized samples (up to 33.2%) as compared to 21.1% in nonoxidized (P < 0.05), which was attributed to glutamine-lysine cross-linking as suggested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

  17. Myosin heavy chain expression and muscle adaptation to chronic oral breathing in rat.

    Science.gov (United States)

    Gelhaye, M; Martrette, J M; Legrand-Frossi, C; Trabalon, M

    2006-12-01

    The purpose of this study was to establish if early chronic oral breathing could induce an ultra-structural adaptation of the diaphragm and orofacial muscles related to oral or nasal breathing. Therefore, we performed a bilateral nasal obstruction at day 8 on rat pups and the myosin heavy chain (MHC) composition of the muscles was analyzed at day 21. Nasal obstruction and the related switch to chronic oral breathing were associated with impaired growth, atrophy of olfactory bulbs, hypertrophy of adrenal glands and reduced muscle growth for all muscles studied except the diaphragm. Furthermore, we detected a smaller decrease of MHC 2b compared to MHC 2a and 2x in levator nasolabialis, a muscle involved with nasal breathing. In masseter superficialis and anterior digastric involved with oral breathing, we observed a smaller decrease of MHC 2a compared to MHC 2b or 2x, respectively. No difference was detected in the diaphragm MHC expression of oral breathing animals. Since the relative expression of fatigue resistant MHC fiber types increased in muscles involved with oral breathing, orofacial muscles seem to present a profile in MHC adapted to the transition from nasal to oral breathing, facilitating respiration.

  18. Effect of Fetal Hypothyroidism on Cardiac Myosin Heavy Chain Expression in Male Rats.

    Science.gov (United States)

    Yousefzadeh, Nasibeh; Jeddi, Sajad; Alipour, Mohammad Reza

    2016-08-01

    Thyroid hormone deficiency during fetal life could affect the cardiac function in later life. The mechanism underlying this action in fetal hypothyroidism (FH) in rats has not been elucidated thus far. The aim of this study is to evaluation the effect of FH on cardiac function in male rats and to determine the contribution of α-myosin heavy chain (MHC) and β-MHC isoforms. Six pregnant female rats were randomly divided into two groups: The hypothyroid group received water containing 6-propyl-2-thiouracil during gestation and the controls consumed tap water. The offspring of the rats were tested in adulthood. Hearts from the FH and control rats were isolated and perfused with langendroff setup for measuring hemodynamic parameters; also, the heart mRNA expressions of α- MHC and β-MHC were measured by qPCR. Baseline LVDP (74.0 ± 3.1 vs. 92.5 ± 3.2 mmHg, p rats than controls. Also, these results showed the same significance in ±dp/dt. In the FH rats, β-MHC expression was higher (201%) and α- MHC expression was lower (47%) than control. Thyroid hormone deficiency during fetal life could attenuate normal cardiac functions in adult rats, an effect at least in part due to the increased expression of β-MHC to α- MHC ratio in the heart.

  19. Myosin heavy chain composition of tiger (Panthera tigris) and cheetah (Acinonyx jubatus) hindlimb muscles.

    Science.gov (United States)

    Hyatt, Jon-Philippe K; Roy, Roland R; Rugg, Stuart; Talmadge, Robert J

    2010-01-01

    Felids have a wide range of locomotor activity patterns and maximal running speeds, including the very fast cheetah (Acinonyx jubatas), the roaming tiger (Panthera tigris), and the relatively sedentary domestic cat (Felis catus). As previous studies have suggested a relationship between the amount and type of activity and the myosin heavy chain (MHC) isoform composition of a muscle, we assessed the MHC isoform composition of selected hindlimb muscles from these three felid species with differing activity regimens. Using gel electrophoresis, western blotting, histochemistry, and immunohistochemistry with MHC isoform-specific antibodies, we compared the MHC composition in the tibialis anterior, medial gastrocnemius (MG), plantaris (Plt), and soleus muscles of the tiger, cheetah, and domestic cat. The soleus muscle was absent in the cheetah. At least one slow (type I) and three fast (types IIa, IIx, and IIb) MHC isoforms were present in the muscles of each felid. The tiger had a high combined percentage of the characteristically slower isoforms (MHCs I and IIa) in the MG (62%) and the Plt (86%), whereas these percentages were relatively low in the MG (44%) and Plt (55%) of the cheetah. In general, the MHC isoform characteristics of the hindlimb muscles matched the daily activity patterns of these felids: the tiger has daily demands for covering long distances, whereas the cheetah has requirements for speed and power. (c) 2009 Wiley-Liss, Inc.

  20. Direct Microtubule-Binding by Myosin-10 Orients Centrosomes toward Retraction Fibers and Subcortical Actin Clouds.

    Science.gov (United States)

    Kwon, Mijung; Bagonis, Maria; Danuser, Gaudenz; Pellman, David

    2015-08-10

    Positioning of centrosomes is vital for cell division and development. In metazoan cells, spindle positioning is controlled by a dynamic pool of subcortical actin that organizes in response to the position of retraction fibers. These actin "clouds" are proposed to generate pulling forces on centrosomes and mediate spindle orientation. However, the motors that pull astral microtubules toward these actin structures are not known. Here, we report that the unconventional myosin, Myo10, couples actin-dependent forces from retraction fibers and subcortical actin clouds to centrosomes. Myo10-mediated centrosome positioning requires its direct microtubule binding. Computational image analysis of large microtubule populations reveals a direct effect of Myo10 on microtubule dynamics and microtubule-cortex interactions. Myo10's role in centrosome positioning is distinct from, but overlaps with, that of dynein. Thus, Myo10 plays a key role in integrating the actin and microtubule cytoskeletons to position centrosomes and mitotic spindles. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Effect of Porcine Akirin2 on Skeletal Myosin Heavy Chain Isoform Expression

    Directory of Open Access Journals (Sweden)

    Xiaoling Chen

    2015-02-01

    Full Text Available Akirin2 plays an important role in skeletal myogenesis. In this study, we found that porcine Akirin2 (pAkirin2 mRNA level was significantly higher in fast extensor digitorum longus (EDL and longissimus lumborum (LL muscles than in slow soleus (SOL muscle of pigs. Overexpression of pAkirin2 increased the number of myosin heavy chain (MHC-positive cells, indicating that pAkirin2 promoted myoblast differentiation. We also found that overexpression of pAkirin2 increased the mRNA expressions of MHCI and MHCIIa and decreased the mRNA expression of MHCIIb. Myocyte enhancer factor 2 (MEF2 and nuclear factor of activated T cells (NFAT are the major downstream effectors of calcineurin. Here we also observed that the mRNA expressions of MEF2C and NFATc1 were notably elevated by pAkirin2 overexpression. Together, our data indicate that the role of pAkirin2 in modulating MHCI and MHCIIa expressions may be achieved through calcineurin/NFATc1 signaling pathway.

  2. Myosin Binding Protein-C Slow: An Intricate Subfamily of Proteins

    Directory of Open Access Journals (Sweden)

    Maegen A. Ackermann

    2010-01-01

    Full Text Available Myosin binding protein C (MyBP-C consists of a family of thick filament associated proteins. Three isoforms of MyBP-C exist in striated muscles: cardiac, slow skeletal, and fast skeletal. To date, most studies have focused on the cardiac form, due to its direct involvement in the development of hypertrophic cardiomyopathy. Here we focus on the slow skeletal form, discuss past and current literature, and present evidence to support that: (i MyBP-C slow comprises a subfamily of four proteins, resulting from complex alternative shuffling of the single MyBP-C slow gene, (ii the four MyBP-C slow isoforms are expressed in variable amounts in different skeletal muscles, (iii at least one MyBP-C slow isoform is preferentially found at the periphery of M-bands and (iv the MyBP-C slow subfamily may play important roles in the assembly and stabilization of sarcomeric M- and A-bands and regulate the contractile properties of the actomyosin filaments.

  3. Myosin-1C uses a novel phosphoinositide-dependent pathway for nuclear localization.

    Science.gov (United States)

    Nevzorov, Ilja; Sidorenko, Ekaterina; Wang, Weihuan; Zhao, Hongxia; Vartiainen, Maria K

    2018-02-01

    Accurate control of macromolecule transport between nucleus and cytoplasm underlines several essential biological processes, including gene expression. According to the canonical model, nuclear import of soluble proteins is based on nuclear localization signals and transport factors. We challenge this view by showing that nuclear localization of the actin-dependent motor protein Myosin-1C (Myo1C) resembles the diffusion-retention mechanism utilized by inner nuclear membrane proteins. We show that Myo1C constantly shuttles in and out of the nucleus and that its nuclear localization does not require soluble factors, but is dependent on phosphoinositide binding. Nuclear import of Myo1C is preceded by its interaction with the endoplasmic reticulum, and phosphoinositide binding is specifically required for nuclear import, but not nuclear retention, of Myo1C. Our results therefore demonstrate, for the first time, that membrane association and binding to nuclear partners is sufficient to drive nuclear localization of also soluble proteins, opening new perspectives to evolution of cellular protein sorting mechanisms. © 2018 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

  4. Non-muscle myosin II in disease: mechanisms and therapeutic opportunities

    Directory of Open Access Journals (Sweden)

    Karen A. Newell-Litwa

    2015-12-01

    Full Text Available The actin motor protein non-muscle myosin II (NMII acts as a master regulator of cell morphology, with a role in several essential cellular processes, including cell migration and post-synaptic dendritic spine plasticity in neurons. NMII also generates forces that alter biochemical signaling, by driving changes in interactions between actin-associated proteins that can ultimately regulate gene transcription. In addition to its roles in normal cellular physiology, NMII has recently emerged as a critical regulator of diverse, genetically complex diseases, including neuronal disorders, cancers and vascular disease. In the context of these disorders, NMII regulatory pathways can be directly mutated or indirectly altered by disease-causing mutations. NMII regulatory pathway genes are also increasingly found in disease-associated copy-number variants, particularly in neuronal disorders such as autism and schizophrenia. Furthermore, manipulation of NMII-mediated contractility regulates stem cell pluripotency and differentiation, thus highlighting the key role of NMII-based pharmaceuticals in the clinical success of stem cell therapies. In this Review, we discuss the emerging role of NMII activity and its regulation by kinases and microRNAs in the pathogenesis and prognosis of a diverse range of diseases, including neuronal disorders, cancer and vascular disease. We also address promising clinical applications and limitations of NMII-based inhibitors in the treatment of these diseases and the development of stem-cell-based therapies.

  5. Distribution of Myosin Attachment Times Predicted from Viscoelastic Mechanics of Striated Muscle

    Directory of Open Access Journals (Sweden)

    Bradley M. Palmer

    2011-01-01

    Full Text Available We demonstrate that viscoelastic mechanics of striated muscle, measured as elastic and viscous moduli, emerge directly from the myosin crossbridge attachment time, tatt, also called time-on. The distribution of tatt was modeled using a gamma distribution with shape parameter, p, and scale parameter, β. At 5 mM MgATP, β was similar between mouse α-MyHC (16.0±3.7 ms and β-MyHC (17.9±2.0 ms, and p was higher (P<0.05 for β-MyHC (5.6±0.4 no units compared to α-MyHC (3.2±0.9. At 1 mM MgATP, p approached a value of 10 in both isoforms, but β rose only in the β-MyHC (34.8±5.8 ms. The estimated mean tatt (i.e., pβ product was longer in the β-MyHC compared to α-MyHC, and became prolonged in both isoforms as MgATP was reduced as expected. The application of our viscoelastic model to these isoforms and varying MgATP conditions suggest that tatt is better modeled as a gamma distribution due to its representing multiple temporal events occurring within tatt compared to a single exponential distribution which assumes only one temporal event within tatt.

  6. Comparative statistical mechanics of myosin molecular motors in rat heart, diaphragm and tracheal smooth muscle.

    Science.gov (United States)

    Lecarpentier, Yves; Claes, Victor; Lecarpentier, Edouard; Blanc, François-Xavier; Joseph, Thierry; Geraets, Bart; Krokidis, Xénophon; Hébert, Jean-Louis

    2011-10-01

    Statistical mechanics establishes a link between microscopic properties of matter and its bulk properties. A. Huxley's equations (1957) [1] provide the necessary phenomenological formalism to use statistical mechanics. We compared statistical mechanics in rat diaphragm in tetanus (tet; n=10) and twitch (tw; n=12) modes, in heart in twitch mode (n=20), and in tracheal smooth muscle in tetanus mode (TSM; n=10). This powerful tool makes it possible to determine: (i) statistical entropy (S) which is related to the dispersal of energy and represents a measure of the degree of disorder in muscular system; (ii) thermodynamic force A/T (chemical affinity A and temperature T); (iii) thermodynamic flow (υ); (iv) entropy production rate (A/T×υ), which quantifies irreversible chemical processes generated by myosin crossbridge (CB) molecular motors. All muscles studied operated near equilibrium, i.e., Atype. All studied muscles differed in terms of statistical entropy, chemical affinity, and entropy production rate. Stimulation mode (tet and tw) modulated CB kinetics and statistical mechanics. All muscle types operated near equilibrium and in a stationary linear regime. Copyright © 2011 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  7. Scattering theory methods for bound state problems

    International Nuclear Information System (INIS)

    Raphael, R.B.; Tobocman, W.

    1978-01-01

    For the analysis of the properties of a bound state system one may use in place of the Schroedinger equation the Lippmann-Schwinger (LS) equation for the wave function or the LS equation for the reactance operator. Use of the LS equation for the reactance operator constrains the solution to have correct asymptotic behaviour, so this approach would appear to be desirable when the bound state wave function is to be used to calculate particle transfer form factors. The Schroedinger equation based N-level analysis of the s-wave bound states of a square well is compared to the ones based on the LS equation. It is found that the LS equation methods work better than the Schroedinger equation method. The method that uses the LS equation for the wave function gives the best results for the wave functions while the method that uses the LS equation for the reactance operator gives the best results for the binding energies. The accuracy of the reactance operator based method is remarkably insensitive to changes in the oscillator constant used for the harmonic oscillator function basis set. It is also remarkably insensitive to the number of nodes in the bound state wave function. (Auth.)

  8. Computational Lower Bounds Using Diagonalization-II

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 4. Computational Lower Bounds Using Diagonalization - II. M V Panduranga Rao. General Article Volume 15 Issue 4 April 2010 pp 337-346 ... Keywords. Diagonalization; time–hierarchy theorem; relativization; Baker–Gill–Solovay theorem.

  9. Bounds on Gromov hyperbolicity constant in graphs

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 122; Issue 1. Bounds on Gromov Hyperbolicity Constant in Graphs. José M Rodríguez José M Sigarreta. Volume 122 ... Spain; Facultad de Matemáticas, Universidad Autónoma de Guerrero, Carlos E. Adame No. 54 Col. Garita, 39650 Acalpulco Gro., Mexico ...

  10. Bogomol'nyi bounds for cosmic strings

    International Nuclear Information System (INIS)

    Comtet, A.; Gibbons, G.W.; Cambridge Univ.

    1987-09-01

    We establish Bogomol'nyi inequalities for the deficit angle of some cylindrically symmetric asymptotically local flat (CALF) spacetimes containing cosmic strings. These results prove the stability against arbitrary cylindrical deformations of those configurations which saturate the bound. Such configurations satisfy first order equations which can, in some cases, be solved exactly

  11. Bounded Rationality of Generalized Abstract Fuzzy Economies

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-01-01

    Full Text Available By using a nonlinear scalarization technique, the bounded rationality model M for generalized abstract fuzzy economies in finite continuous spaces is established. Furthermore, by using the model M, some new theorems for structural stability and robustness to (λ,ϵ-equilibria of generalized abstract fuzzy economies are proved.

  12. Theoretical Bounds of Direct Binary Search Halftoning.

    Science.gov (United States)

    Liao, Jan-Ray

    2015-11-01

    Direct binary search (DBS) produces the images of the best quality among half-toning algorithms. The reason is that it minimizes the total squared perceived error instead of using heuristic approaches. The search for the optimal solution involves two operations: (1) toggle and (2) swap. Both operations try to find the binary states for each pixel to minimize the total squared perceived error. This error energy minimization leads to a conjecture that the absolute value of the filtered error after DBS converges is bounded by half of the peak value of the autocorrelation filter. However, a proof of the bound's existence has not yet been found. In this paper, we present a proof that shows the bound existed as conjectured under the condition that at least one swap occurs after toggle converges. The theoretical analysis also indicates that a swap with a pixel further away from the center of the autocorrelation filter results in a tighter bound. Therefore, we propose a new DBS algorithm which considers toggle and swap separately, and the swap operations are considered in the order from the edge to the center of the filter. Experimental results show that the new algorithm is more efficient than the previous algorithm and can produce half-toned images of the same quality as the previous algorithm.

  13. Monotonicity and bounds on Bessel functions

    Directory of Open Access Journals (Sweden)

    Larry Landau

    2000-07-01

    Full Text Available survey my recent results on monotonicity with respect to order of general Bessel functions, which follow from a new identity and lead to best possible uniform bounds. Application may be made to the "spreading of the wave packet" for a free quantum particle on a lattice and to estimates for perturbative expansions.

  14. Threshold Circuit Lower Bounds on Cryptographic Functions

    NARCIS (Netherlands)

    E. Kiltz (Eike); H.U. Simon

    2005-01-01

    textabstractIn this work, we are interested in non-trivial upper bounds on the spectral norm of binary matrices $M$ from {-1, 1} $^{N × N}$. It is known that the distributed Boolean function represented by $M$ is hard to compute in various restricted models of computation if the spectral norm is

  15. Strong WW Interaction at LHC

    Energy Technology Data Exchange (ETDEWEB)

    Pelaez, Jose R

    1998-12-14

    We present a brief pedagogical introduction to the Effective Electroweak Chiral Lagrangians, which provide a model independent description of the WW interactions in the strong regime. When it is complemented with some unitarization or a dispersive approach, this formalism allows the study of the general strong scenario expected at the LHC, including resonances.

  16. The quality of zero bounds for complex polynomials.

    Science.gov (United States)

    Dehmer, Matthias; Tsoy, Yury Robertovich

    2012-01-01

    In this paper, we evaluate the quality of zero bounds on the moduli of univariate complex polynomials. We select classical and recently developed bounds and evaluate their quality by using several sets of complex polynomials. As the quality of priori bounds has not been investigated thoroughly, our results can be useful to find optimal bounds to locate the zeros of complex polynomials.

  17. Elucidating the mechanism of wound contraction: rapid versus sustained myosin ATPase activity in attached-delayed-released compared with free-floating fibroblast-populated collagen lattices.

    Science.gov (United States)

    Paul Ehrlich, H; Sun, Bonnie; Kainth, Koijan S; Kromah, Fatuma

    2006-01-01

    Wound contraction closes open wounds by the generation of contractile forces within granulation tissue. We investigated the mechanism of wound contraction using the in vitro fibroblast-populated collagen lattice (FPCL) contraction model. The contraction of the free-floating (FF)-FPCL is through rapid myosin ATPase activity, while the contraction of the attached-delayed-released (ADR)-FPCL is through sustained myosin ATPase activity. All FPCLs were cast identically and the contraction of FF-FPCLs was recorded daily for 4 days and the contraction of ADR-FPCLs was recorded 1 hour after release on day 4. At day, 4 cell numbers were determined and cells undergoing apoptosis were identified and counted. Differences in sustained and rapid myosin ATPase activity were shown by added inosine triphosphate-induced cell contraction in permeabilized fibroblast monolayer preparations. At 2 days, the FF-FPCLs were mostly contracted, while an ADR-FPCL completed contraction 1 hour after release at day 4. Contracted myofibroblasts, identified by alpha-smooth muscle actin-stained stress fibers, were identified in contracted ADR-FPCL, whereas elongated fibroblasts were identified in contracted FF-FPCLs. Vanadate inhibited both inosine triphosphate-induced cell contraction and ADR-FPCL contraction, but neither inhibited ATP-induced cell contraction or FF-FPCL contraction. Genistein inhibited FF-FPCL contraction, but not ADR-FPCL contraction. Advancing tyrosine phosphorylation in fibroblasts promotes rapid myosin ATPase activity, while advancing tyrosine dephosphorylation in myofibroblasts promotes sustained myosin ATPase. The ADR-FPCL had a reduced cell count and a greater proportion of cells had entered apoptosis compared with FF-FPCL. These experiments show that FF-FPCL contraction is through elongated fibroblasts and rapid myosin ATPase, requiring tyrosine phosphorylation. In contrast, the mechanism for ADR-FPCL contraction is through cell contraction by sustained myosin ATPase

  18. Strong-back safety latch

    International Nuclear Information System (INIS)

    DeSantis, G.N.

    1995-01-01

    The calculation decides the integrity of the safety latch that will hold the strong-back to the pump during lifting. The safety latch will be welded to the strong-back and will latch to a 1.5-in. dia cantilever rod welded to the pump baseplate. The static and dynamic analysis shows that the safety latch will hold the strong-back to the pump if the friction clamps fail and the pump become free from the strong-back. Thus, the safety latch will meet the requirements of the Lifting and Rigging Manual for under the hook lifting for static loading; it can withstand shock loads from the strong-back falling 0.25 inch

  19. Strong-back safety latch

    Energy Technology Data Exchange (ETDEWEB)

    DeSantis, G.N.

    1995-03-06

    The calculation decides the integrity of the safety latch that will hold the strong-back to the pump during lifting. The safety latch will be welded to the strong-back and will latch to a 1.5-in. dia cantilever rod welded to the pump baseplate. The static and dynamic analysis shows that the safety latch will hold the strong-back to the pump if the friction clamps fail and the pump become free from the strong-back. Thus, the safety latch will meet the requirements of the Lifting and Rigging Manual for under the hook lifting for static loading; it can withstand shock loads from the strong-back falling 0.25 inch.

  20. Bounds on fluid permeability for viscous flow through porous media

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1985-01-01

    General properties of variational bounds on Darcy's constant for slow viscous flow through porous media are studied. The bounds are also evaluated numerically for the penetrable sphere model. The bound of Doi depending on two-point correlations and the analytical bound of Weissberg and Prager give comparable results in the low density limit but the analytical bound is superior for higher densities. Prager's bound depending on three-point correlation functions is worse than the analytical bound at low densities but better (although comparable to it) at high densities. A procedure for methodically improving Prager's three point bound is presented. By introducing a Gaussian trial function, the three-point bound is improved by an order of magnitude for moderate values of porosity. The new bounds are comparable in magnitude to the Kozeny--Carman empirical relation for porous materials