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Sample records for boundaries regulates formation

  1. Line tension at lipid phase boundaries regulates formation of membrane vesicles in living cells

    DEFF Research Database (Denmark)

    Vind-Kezunovic, Dina; Helix Nielsen, Claus; Wojewodzka, Urszula;

    2008-01-01

    Ternary lipid compositions in model membranes segregate into large-scale liquid-ordered (L-o) and liquid-disordered (L-d) phases. Here, we show mu m-sized lipid domain separation leading to vesicle formation in unperturbed human HaCaT keratinocytes. Budding vesicles in the apical portion...... of the plasma membrane were predominantly labelled with L-d markers 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate, 1,1'-dilinoleyl-3.3.3',3'-tetramethylindocarbocyanine perchlorate, 1,1'-didodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate and weakly stained by L-o marker fluorescein......-labeled cholera toxin B subunit which labels ganglioside GM(1) enriched plasma membrane rafts. Cholesterol depletion with methyl-beta-cyclodextrin enhanced DiI vesiculation, GM(1)/DiI domain separation and was accompanied by a detachment of the subcortical cytoskeleton from the plasma membrane. Based...

  2. Line tension at lipid phase boundaries regulates formation of membrane vesicles in living cells

    DEFF Research Database (Denmark)

    Vind-Kezunovic, D.; Nielsen, C.H.; Wojewodzka, U.;

    2008-01-01

    Ternary lipid compositions in model membranes segregate into large-scale liquid-ordered (L(o)) and liquid-disordered (L(d)) phases. Here, we show mum-sized lipid domain separation leading to vesicle formation in unperturbed human HaCaT keratinocytes. Budding vesicles in the apical portion...... of the plasma membrane were predominantly labelled with L(d) markers 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate, 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate, 1,1'-didodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate and weakly stained by L(o) marker...... fluorescein-labeled cholera toxin B subunit which labels ganglioside GM(1) enriched plasma membrane rafts. Cholesterol depletion with methyl-beta-cyclodextrin enhanced DiI vesiculation, GM(1)/DiI domain separation and was accompanied by a detachment of the subcortical cytoskeleton from the plasma membrane...

  3. ON A PARABOLIC FREE BOUNDARY EQUATION MODELING PRICE FORMATION

    KAUST Repository

    MARKOWICH, P. A.

    2009-10-01

    We discuss existence and uniqueness of solutions for a one-dimensional parabolic evolution equation with a free boundary. This problem was introduced by Lasry and Lions as description of the dynamical formation of the price of a trading good. Short time existence and uniqueness is established by a contraction argument. Then we discuss the issue of global-in-time-extension of the local solution which is closely related to the regularity of the free boundary. We also present numerical results. © 2009 World Scientific Publishing Company.

  4. New Theories on Boundary Layer Transition and Turbulence Formation

    Directory of Open Access Journals (Sweden)

    Chaoqun Liu

    2012-01-01

    Full Text Available This paper is a short review of our recent DNS work on physics of late boundary layer transition and turbulence. Based on our DNS observation, we propose a new theory on boundary layer transition, which has five steps, that is, receptivity, linear instability, large vortex structure formation, small length scale generation, loss of symmetry and randomization to turbulence. For turbulence generation and sustenance, the classical theory, described with Richardson's energy cascade and Kolmogorov length scale, is not observed by our DNS. We proposed a new theory on turbulence generation that all small length scales are generated by “shear layer instability” through multiple level ejections and sweeps and consequent multiple level positive and negative spikes, but not by “vortex breakdown.” We believe “shear layer instability” is the “mother of turbulence.” The energy transferring from large vortices to small vortices is carried out by multiple level sweeps, but does not follow Kolmogorov's theory that large vortices pass energy to small ones through vortex stretch and breakdown. The loss of symmetry starts from the second level ring cycle in the middle of the flow field and spreads to the bottom of the boundary layer and then the whole flow field.

  5. Dwarf galaxy formation with H2-regulated star formation

    CERN Document Server

    Kuhlen, M; Madau, P; Smith, B; Wise, J

    2011-01-01

    We describe cosmological galaxy formation simulations with the adaptive mesh refinement code Enzo that incorporate a star formation prescription regulated by the local abundance of molecular hydrogen. We show that this H2-regulated prescription leads to a suppression of star formation in low mass halos (M_h 4, alleviating some of the dwarf galaxy problems faced by theoretical galaxy formation models. H2 regulation modifies the efficiency of star formation of cold gas directly, rather than indirectly reducing the cold gas content with "supernova feedback". We determine the local H2 abundance in our most refined grid cells (76 proper parsec in size at z=4) by applying the model of Krumholz, McKee, & Tumlinson, which is based on idealized 1D radiative transfer calculations of H2 formation-dissociation balance in ~100 pc atomic--molecular complexes. Our H2-regulated simulations are able to reproduce the empirical (albeit lower z) Kennicutt-Schmidt relation, including the low Sigma_gas cutoff due to the transi...

  6. HOW GALACTIC ENVIRONMENT REGULATES STAR FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Meidt, Sharon E. [Max-Planck-Institut für Astronomie/Königstuhl 17 D-69117 Heidelberg (Germany)

    2016-02-10

    In a new simple model I reconcile two contradictory views on the factors that determine the rate at which molecular clouds form stars—internal structure versus external, environmental influences—providing a unified picture for the regulation of star formation in galaxies. In the presence of external pressure, the pressure gradient set up within a self-gravitating turbulent (isothermal) cloud leads to a non-uniform density distribution. Thus the local environment of a cloud influences its internal structure. In the simple equilibrium model, the fraction of gas at high density in the cloud interior is determined simply by the cloud surface density, which is itself inherited from the pressure in the immediate surroundings. This idea is tested using measurements of the properties of local clouds, which are found to show remarkable agreement with the simple equilibrium model. The model also naturally predicts the star formation relation observed on cloud scales and at the same time provides a mapping between this relation and the closer-to-linear molecular star formation relation measured on larger scales in galaxies. The key is that pressure regulates not only the molecular content of the ISM but also the cloud surface density. I provide a straightforward prescription for the pressure regulation of star formation that can be directly implemented in numerical models. Predictions for the dense gas fraction and star formation efficiency measured on large-scales within galaxies are also presented, establishing the basis for a new picture of star formation regulated by galactic environment.

  7. Slow solar wind boundaries and implication for its formation

    Science.gov (United States)

    Ko, Yuan-Kuen; Roberts, Aaron; Lepri, Susan; Kocher, Manan

    2015-04-01

    Solar wind and the associated magnetic field permeate the heliosphere. Their temporal and spatial variations contribute significantly in the large range of variations in related geomagnetic effects as well as in the properties of solar energetic particles. Among the least understood is the slow solar wind for how it is formed at the Sun and what causes the large variations in its physical properties. This work investigates the variations in the slow solar wind streams measured in-situ at 1 AU and the correlations among the protons, heavy ions, suprathermal electrons, and magnetic field properties. Besides well-established correlations among the proton speed, proton temperature and ion charge states, we also found certain distinct characteristics in the correlation and temporal relationship between the ion charge states, proton velocity fluctuations and, in many cases, suprathermal electron halos. The implications from our findings in the slow wind formation and whether the slow wind has a distinct boundary with the fast wind will be discussed.

  8. On a price formation free boundary model by Lasry & Lions: The Neumann problem

    CERN Document Server

    Caffarelli, Luis A; Wolfram, Marie-Therese

    2011-01-01

    We discuss local and global existence and uniqueness for the price formation free boundary model with homogeneous Neumann boundary conditions introduced by Lasry & Lions in 2007. The results are based on a transformation of the problem to the heat equation with nonstandard boundary conditions. The free boundary becomes the zero level set of the solution of the heat equation. The transformation allows us to construct an explicit solution and discuss the behavior of the free boundary. Global existence can be verified under certain conditions on the free boundary and examples of non-existence are given.

  9. Formation of the wave compressional boundary in the earth's foreshock

    Science.gov (United States)

    Skadron, George; Holdaway, Robert D.; Lee, Martin A.

    1988-01-01

    Using an evolutionary model and allowing for nonuniform proton injection and wave growth rates, the compressional wave boundaries corresponding to IMF inclinations to the solar wind of theta(BV) equal to 45 and 25 deg were located. The compressional boundaries deduced from this model were found to support the results of Greenstadt and Baum (1986) who have concluded that the observed compressional boundaries are incompatible with wave growth at a fixed growth rate, due to the interaction of a uniform beam with the solar wind. The results indicate, however, that the compressional boundaries are quite compatible with nonuniform beams and growth rates which result from the coupled evolution of the energetic protons and the waves with which they interact. It was found that, in the solar wind frame, the dominant wave-particle interaction in the outer foreshock is the damping of inward propagating (toward the shock) left-polarized waves, producing a magnetically quiet region immediately downstream of the foreshock boundary.

  10. Maori intellectual property rights and the formation of ethnic boundaries

    OpenAIRE

    Meijl, A.H.M. van

    2009-01-01

    This article questions and contextualizes the emergence of a discourse of intellectual property rights in Māori society. It is argued that Māori claims regarding intellectual property function primarily to demarcate ethnic boundaries between Māori and non-Māori. Māori consider the reinforcement of ethnic boundaries necessary since they experience their society and distinctive way of life as endangered both by the foreign consumption or misappropriation of aspects of their authentic cultural f...

  11. A distinct magnetic property of the inner penumbral boundary. Formation of a stable umbra-penumbra boundary in a sunspot

    Science.gov (United States)

    Jurčák, J.; Bello González, N.; Schlichenmaier, R.; Rezaei, R.

    2015-08-01

    Context. A sunspot emanates from a growing pore or protospot. In order to trigger the formation of a penumbra, large inclinations at the outskirts of the protospot are necessary. The penumbra develops and establishes by colonising both umbral areas and granulation. Evidence for a unique stable boundary value for the vertical component of the magnetic field strength, Bstablever, was found along the umbra-penumbra boundary of developed sunspots. Aims: We study the changing value of Bver as the penumbra forms and as it reaches a stable state. We compare this with the corresponding value in fully developed penumbrae. Methods: We use broadband G-band images and spectropolarimetric GFPI/VTT data to study the evolution of and the vertical component of the magnetic field on a forming umbra-penumbra boundary. For comparison with stable sunspots, we also analyse the two maps observed by Hinode/SP on the same spot after the penumbra formed. Results: The vertical component of the magnetic field, Bver, at the umbra-penumbra boundary increases during penumbra formation owing to the incursion of the penumbra into umbral areas. After 2.5 h, the penumbra reaches a stable state as shown by the GFPI data. At this stable stage, the simultaneous Hinode/SP observations show a Bver value comparable to that of umbra-penumbra boundaries of fully fledged sunspots. Conclusions: We confirm that the umbra-penumbra boundary, traditionally defined by an intensity threshold, is also characterised by a distinct canonical magnetic property, namely by Bverstable. During the penumbra formation process, the inner penumbra extends into regions where the umbra previously prevailed. Hence, in areas where Bverboundary settles at Bverstable, which hints toward the role of Bverstable as inhibitor of the penumbral mode of magneto-convection.

  12. LATERAL ORGAN BOUNDARIES DOMAIN transcription factors direct callus formation in Arabidopsis regeneration

    Institute of Scientific and Technical Information of China (English)

    Mingzhu Fan; Chongyi Xu; Ke Xu; Yuxin Hu

    2012-01-01

    The remarkable regeneration capability of plant tissues or organs under culture conditions has underlain an extensive practice for decades.The initial step in plant in vitro regeneration often involves the induction of a pluripotent cell mass termed callus,which is driven by the phytohormone auxin and occurs via a root development pathway.However,the key molecules governing callus formation remain unknown.Here we demonstrate that Arabidopsis LATERAL ORGAN BOUNDARIES DOMAIN (LBD)/ASYMMETRIC LEAVES2-LIKE (ASL) transcription factors are involved in the control of callus formation program.The four LBD genes downstream of AUXIN RESPONSE FACTORs (ARFs),LBD16,LBD17,LBD18 and LBD29,are rapidly and dramatically induced by callus-inducing medium (CIM) in multiple organs.Ectopic expression of each of the four LBD genes in Arabidopsis is sufficient to trigger spontaneous callus formation without exogenous phytohormones,whereas suppression of LBD function inhibits the callus formation induced by CIM.Moreover,the callus triggered by LBD resembles that induced by CIM by characteristics of ectopically activated root meristem genes and efficient regeneration capacity.These findings define LBD transcription factors as key regulators in the callus induction process,thereby establishing a molecular link between auxin signaling and the plant regeneration program.

  13. Maori intellectual property rights and the formation of ethnic boundaries

    NARCIS (Netherlands)

    Meijl, A.H.M. van

    2009-01-01

    This article questions and contextualizes the emergence of a discourse of intellectual property rights in Māori society. It is argued that Māori claims regarding intellectual property function primarily to demarcate ethnic boundaries between Māori and non-Māori. Māori consider the reinforcement of e

  14. Mechanical regulation of vascular network formation in engineered matrices.

    Science.gov (United States)

    Lesman, Ayelet; Rosenfeld, Dekel; Landau, Shira; Levenberg, Shulamit

    2016-01-15

    Generation of vessel networks within engineered tissues is critical for integration and perfusion of the implanted tissue in vivo. The effect of mechanical cues in guiding and stabilizing the vessels has begun to attract marked interest. This review surveys the impact of mechanical cues on formation of vascular networks in 2D and 3D gel matrices. We give less emphasis to regulation of endothelial monolayers and single endothelial cells. Several vascularization models have consistently found that the stress generated in the gel, and encountered by embedded cells, control various aspects of vascular network formation, including sprouting, branching, alignment, and vessel maturation. This internal stress is generated by cell contractile forces, and is balanced by gel stiffness and boundary constrains imposed on the gel. Actin and myosin II are key molecular players in controlling initiation of vessel sprouting and branching morphogenesis. Additionally, the impact of external mechanical cues on tissue vascularization, and studies supporting the notion that mechanical forces regulate vascularization in the live animal are reviewed.

  15. Boundary conditions for the formation of the Moon

    NARCIS (Netherlands)

    Reuver, Maarten; de Meijer, R. J.; ten Kate, I. L.; van Westrenen, W.

    2016-01-01

    Recent measurements of the chemical and isotopic composition of lunar samples indicate that the Moon's bulk composition shows great similarities with the composition of the silicate Earth. Moon formation models that attempt to explain these similarities make a wide variety of assumptions about the p

  16. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    Directory of Open Access Journals (Sweden)

    J. Lauros

    2010-08-01

    Full Text Available We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical profile of particle number distribution does not correspond to observations. Instead organic induced nucleation leads to good agreement confirming the relevance of the aerosol formation mechanism including organic compounds emitted by biosphere.

    Simulation of aerosol concentration inside the atmospheric boundary layer during nucleation days shows highly dynamical picture, where particle formation is coupled with chemistry and turbulent transport. We have demonstrated suitability of our turbulent mixing scheme in reproducing most important characteristics of particle dynamics inside the atmospheric boundary layer. Deposition and particle flux simulations show that deposition affects noticeably only the smallest particles at the lowest part of the atmospheric boundary layer.

  17. Regulating mechanical tension at compartment boundaries in Drosophila.

    Science.gov (United States)

    Michel, Marcus; Dahmann, Christian

    2016-10-01

    During animal development, cells with similar function and fate often stay together and sort out from cells with different fates. In Drosophila wing imaginal discs, cells of anterior and posterior fates are separated by a straight compartment boundary. Separation of anterior and posterior cells requires the homeodomain-containing protein Engrailed, which is expressed in posterior cells. Engrailed induces the expression of the short-range signaling molecule Hedgehog in posterior cells and confines Hedgehog signal transduction to anterior cells. Transduction of the Hedgehog signal in anterior cells is required for the separation of anterior and posterior cells. Previous work showed that this separation of cells involves a local increase in mechanical tension at cell junctions along the compartment boundary. However, how mechanical tension was locally increased along the compartment boundary remained unknown. A recent paper now shows that the difference in Hedgehog signal transduction between anterior and posterior cells is necessary and sufficient to increase mechanical tension. The local increase in mechanical tension biases junctional rearrangements during cell intercalations to maintain the straight shape of the compartment boundary. These data highlight how developmental signals can generate patterns of mechanical tension important for tissue organization.

  18. Lbx2 regulates formation of myofibrils

    Directory of Open Access Journals (Sweden)

    Westerfield Monte

    2009-02-01

    Full Text Available Abstract Background Skeletal muscle differentiation requires assembly of contractile proteins into organized myofibrils. The Drosophila ladybird homeobox gene (lad functions in founder cells of the segmental border muscle to promote myoblast fusion and muscle shaping. Tetrapods have two homologous genes (Lbx. Lbx1 functions in migration and/or proliferation of hypaxial myoblasts, whereas the function of Lbx2 is poorly understood. Results To elucidate the role of Lbx in vertebrate myogenesis, we examined Lbx function in zebrafish. Zebrafish lbx2 transcripts appear in newly formed paraxial mesoderm and become restricted to adaxial cells, precursors of slow muscle. Slow muscles lose lbx2 expression as they differentiate, while a subset of differentiating fast muscle cells transiently expresses lbx2. Fin and hyoid muscle express lbx2 later. In contrast, lbx1b expression first appears lateral to the somites at late segmentation stages and is later restricted to fin muscle. Morpholino knockdown of Lbx1b and Lbx2 suppresses hypaxial muscle development. Moreover, knockdown of Lbx2 results in malformation of muscle fibers and reduced fusion of fast precursors, although no obvious effects on induction or specification are observed. Expression of myofilament genes, including actin and myosin, requires the engrailed repressor domain of Lbx2. Conclusion Our results elucidate a new function of Lbx2 as a regulator of myofibril formation.

  19. On a price formation free boundary model by Lasry and Lions

    KAUST Repository

    Caffarelli, Luis A.

    2011-06-01

    We discuss global existence and asymptotic behaviour of a price formation free boundary model introduced by Lasry and Lions in 2007. Our results are based on a construction which transforms the problem into the heat equation with specially prepared initial datum. The key point is that the free boundary present in the original problem becomes the zero level set of this solution. Using the properties of the heat operator we can show global existence, regularity and asymptotic results of the free boundary. 2011 Académie des sciences.

  20. Surface transition on ice induced by the formation of a grain boundary.

    Directory of Open Access Journals (Sweden)

    Christian Pedersen

    Full Text Available Interfaces between individual ice crystals, usually referred to as grain boundaries, play an important part in many processes in nature. Grain boundary properties are, for example, governing the sintering processes in snow and ice which transform a snowpack into a glacier. In the case of snow sintering, it has been assumed that there are no variations in surface roughness and surface melting, when considering the ice-air interface of an individual crystal. In contrast to that assumption, the present work suggests that there is an increased probability of molecular surface disorder in the vicinity of a grain boundary. The conclusion is based on the first detailed visualization of the formation of an ice grain boundary. The visualization is enabled by studying ice crystals growing into contact, at temperatures between -20°C and -15°C and pressures of 1-2 Torr, using Environmental Scanning Electron Microscopy. It is observed that the formation of a grain boundary induces a surface transition on the facets in contact. The transition does not propagate across facet edges. The surface transition is interpreted as the spreading of crystal dislocations away from the grain boundary. The observation constitutes a qualitatively new finding, and can potentially increase the understanding of specific processes in nature where ice grain boundaries are involved.

  1. Nanocomposites with thermosetting matrix: structure formation at the interphase boundary

    Directory of Open Access Journals (Sweden)

    KOROLEV Evgenij Valerjevich

    2014-06-01

    Full Text Available Composites with thermosetting matrix are often characterized by elevated values of operational properties – flexural and compressive strength, resistance to aggressive environments, etc. At the same time the cost of most thermosets (particularly – epoxy resins is quite high. Because of this the area of application of polymer composites in construction is limited. One of such application is the creation of multifunctional coatings. The high cost of resin dictates the need to improve the operational properties to ensure economic efficiency. So far, the known way to improve the operational properties is to produce nanoscale interfacial layer between fine filler and matrix in block. This way proved to be effective, but mechanism of the improvement is still uncertain. There areat least two different theories – so-called «adhesion theory» and «theory of deformable layer». The investigation is complicated by the variety of oligomers, hardeners (crosslinking agents and precursors of nanomodifiers. It is becoming more common lately to use adducts of aliphatic amines and epoxy oligomers as hardeners. As precursors of nanomodifiers the organosilicon compounds with siloxane bond in the main chain can be successfully used. In this paper we present results of investigation of a model system comprised of oligomer, crosslinking agent and precursor. The analysis of structure is carried out by means of Raman spectroscopy and atomic force microscopy. It is shown that at gelation point modifier has no significant effect on the chemical composition of the curing products; nevertheless, the admixture of modifier reduces the regularity of the emerging three-dimensional spatial net of thermoset. After completion of curing process the irregular spatial grid is still present. This indicates that in composites admixture of organosilicon precursors may lead to the formation of transition layer with reduced modulus of elasticity. Such layer, in turn, causes stress

  2. Topology of magnetic flux ropes and formation of fossil flux transfer events and boundary layer plasmas

    Science.gov (United States)

    Lee, L. C.; Ma, Z. W.; Fu, Z. F.; Otto, A.

    1993-01-01

    A mechanism for the formation of fossil flux transfer events and the low-level boundary layer within the framework of multiple X-line reconnection is proposed. Attention is given to conditions for which the bulk of magnetic flux in a flux rope of finite extent has a simple magnetic topology, where the four possible connections of magnetic field lines are: IMF to MSP, MSP to IMF, IMF to IMF, and MSP to MSP. For a sufficient relative shift of the X lines, magnetic flux may enter a flux rope from the magnetosphere and exit into the magnetosphere. This process leads to the formation of magnetic flux ropes which contain a considerable amount of magnetosheath plasma on closed magnetospheric field lines. This process is discussed as a possible explanation for the formation of fossil flux transfer events in the magnetosphere and the formation of the low-latitude boundary layer.

  3. Traveling waves and dynamical formation of autonomous pacemakers in a bistable medium with periodic boundary conditions

    Science.gov (United States)

    Shepelev, Igor A.; Vadivasova, Tatiana E.; Postnov, Dmitry E.

    2015-03-01

    The problem of spatiotemporal pattern formation in the wall of arterial vesselsmay be reduced to 1D or 2D models of nonlinear active medium. We address this problem using the discrete array of non-oscillating (bistable) active units. We show how the specific choice of initial conditions in a 1D model with periodic boundary conditions triggers the self-sustained behaviour. We reveal the core of observed effects being the dynamical formation of localized (few-element size) autonomous pacemakers.

  4. Inside-Out Planet Formation. III. Planet-disk interaction at the dead zone inner boundary

    OpenAIRE

    Hu, Xiao; Zhu, Zhaohuan; Tan, Jonathan C.; Chatterjee, Sourav

    2015-01-01

    The Kepler mission has discovered more than 4000 exoplanet candidates. Many are in systems with tightly packed inner planets. Inside-Out Planet Formation (IOPF) has been proposed to explain these systems. It involves sequential in situ planet formation at the local pressure maximum of a retreating dead zone inner boundary (DZIB). Pebbles accumulate at this pressure trap, which builds up a ring, and then a planet. The planet is expected to grow until it opens a gap, which helps to both truncat...

  5. Hormonal Regulation of Tuber Formation in Potato

    NARCIS (Netherlands)

    Aksenova, N.P.; Sergeeva, L.; Kolachevskaya, O.O.; Romanov, G.A.

    2013-01-01

    Tubers of potato (Solanum tuberosum L.) plants serve as organs for vegetative propagation and stock of matter and energy for the next generation. Tuber formation is a complex process involving several successive stages: stolon formation and growth, induction of tuberization, tuber initiation and fur

  6. Transcription rate and transcript length drive formation of chromosomal interaction domain boundaries.

    Science.gov (United States)

    Le, Tung Bk; Laub, Michael T

    2016-07-15

    Chromosomes in all organisms are highly organized and divided into multiple chromosomal interaction domains, or topological domains. Regions of active, high transcription help establish and maintain domain boundaries, but precisely how this occurs remains unclear. Here, using fluorescence microscopy and chromosome conformation capture in conjunction with deep sequencing (Hi-C), we show that in Caulobacter crescentus, both transcription rate and transcript length, independent of concurrent translation, drive the formation of domain boundaries. We find that long, highly expressed genes do not form topological boundaries simply through the inhibition of supercoil diffusion. Instead, our results support a model in which long, active regions of transcription drive local decompaction of the chromosome, with these more open regions of the chromosome forming spatial gaps in vivo that diminish contacts between DNA in neighboring domains. These insights into the molecular forces responsible for domain formation in Caulobacter likely generalize to other bacteria and possibly eukaryotes. PMID:27288403

  7. New-particle formation events in a continental boundary layer: first results from the SATURN experiment

    Directory of Open Access Journals (Sweden)

    F. Stratmann

    2003-01-01

    Full Text Available During the SATURN experiment, which took place from 27 May to 14 June 2002, new particle formation in the continental boundary layer was investigated. Simultaneous ground-based and tethered-balloon-borne measurements were performed, including meteorological parameters, particle number concentrations and size distributions, gaseous precursor concentrations and SODAR and LIDAR observations. Newly formed particles were observed inside the residual layer, before the break-up process of the nocturnal inversion, and inside the mixing layer throughout the break-up of the nocturnal inversion and during the evolution of the planetary boundary layer.

  8. Epigenetic Regulation of Memory Formation and Maintenance

    Science.gov (United States)

    Zovkic, Iva B.; Guzman-Karlsson, Mikael C.; Sweatt, J. David

    2013-01-01

    Understanding the cellular and molecular mechanisms underlying the formation and maintenance of memories is a central goal of the neuroscience community. It is well regarded that an organism's ability to lastingly adapt its behavior in response to a transient environmental stimulus relies on the central nervous system's capability for structural…

  9. The Role of Boundary Spanners in the Formation of Customer Attractiveness

    DEFF Research Database (Denmark)

    Hald, Kim Sundtoft

    2012-01-01

    This paper examines the question of how to understand the formation of suppliers perceived customer attractiveness. It argues that existing conceptualization of buyer–supplier relationships are too simplistic to understand the full complexity involved in the formation of such perceptions, and mod......This paper examines the question of how to understand the formation of suppliers perceived customer attractiveness. It argues that existing conceptualization of buyer–supplier relationships are too simplistic to understand the full complexity involved in the formation of such perceptions...... of action” is deployed. The analysis demonstrates how suppliers' formation of perceptions related to customer attractiveness can be understood as constituted through a set of discrete historical means/ends alignments and misalignments between boundary spanning roles in the involved organizations....

  10. Boundaries determine the formation energies of lattice defects in two-dimensional buckled materials

    Science.gov (United States)

    Jain, Sandeep K.; Juričić, Vladimir; Barkema, Gerard T.

    2016-07-01

    Lattice defects are inevitably present in two-dimensional materials, with direct implications on their physical and chemical properties. We show that the formation energy of a lattice defect in buckled two-dimensional crystals is not uniquely defined as it takes different values for different boundary conditions even in the thermodynamic limit, as opposed to their perfectly planar counterparts. Also, the approach to the thermodynamic limit follows a different scaling: inversely proportional to the logarithm of the system size for buckled materials, rather than the usual power-law approach. In graphene samples of ˜1000 atoms, different boundary conditions can cause differences exceeding 10 eV. Besides presenting numerical evidence in simulations, we show that the universal features in this behavior can be understood with simple bead-spring models. Fundamentally, our findings imply that it is necessary to specify the boundary conditions for the energy of the lattice defects in the buckled two-dimensional crystals to be uniquely defined, and this may explain the lack of agreement in the reported values of formation energies in graphene. We argue that boundary conditions may also have an impact on other physical observables such as the melting temperature.

  11. Formation and Regulation of Mitochondrial Membranes

    Directory of Open Access Journals (Sweden)

    Laila Cigana Schenkel

    2014-01-01

    Full Text Available Mitochondrial membrane phospholipids are essential for the mitochondrial architecture, the activity of respiratory proteins, and the transport of proteins into the mitochondria. The accumulation of phospholipids within mitochondria depends on a coordinate synthesis, degradation, and trafficking of phospholipids between the endoplasmic reticulum (ER and mitochondria as well as intramitochondrial lipid trafficking. Several studies highlight the contribution of dietary fatty acids to the remodeling of phospholipids and mitochondrial membrane homeostasis. Understanding the role of phospholipids in the mitochondrial membrane and their metabolism will shed light on the molecular mechanisms involved in the regulation of mitochondrial function and in the mitochondrial-related diseases.

  12. Zigzag Inversion Domain Boundaries in Indium Zinc Oxide-Based Nanowires: Structure and Formation

    OpenAIRE

    Goldstein, Anna P.

    2014-01-01

    Existing models for the crystal structure of indium zinc oxide (IZO) and indium iron zinc oxide (IFZO) conflict with electron microscopy data. We propose a model based on imaging and spectroscopy of IZO and IFZO nanowires and verify it using density functional theory. The model features a {12?1} ?zigzag? layer, which is an inversion domain boundary containing 5-coordinate indium and/or iron atoms. Higher values are observed for greater proportion of iron. We suggest a mechanism of formation i...

  13. Thermodynamic analysis of carbon formation boundary and reforming performance for steam reforming of dimethyl ether

    Science.gov (United States)

    Faungnawakij, Kajornsak; Kikuchi, Ryuji; Eguchi, Koichi

    Thermodynamic analysis of dimethyl ether steam reforming (DME SR) was investigated for carbon formation boundary, DME conversion, and hydrogen yield for fuel cell application. The equilibrium calculation employing Gibbs free minimization was performed to figure out the required steam-to-carbon ratio (S/C = 0-5) and reforming temperature (25-1000 °C) where coke formation was thermodynamically unfavorable. S/C, reforming temperature and product species strongly contributed to the coke formation and product composition. When chemical species DME, methanol, CO 2, CO, H 2, H 2O and coke were considered, complete conversion of DME and hydrogen yield above 78% without coke formation were achieved at the normal operating temperatures of molten carbonate fuel cell (600 °C) and solid oxide fuel cell (900 °C), when S/C was at or above 2.5. When CH 4 was favorable, production of coke and that of hydrogen were significantly suppressed.

  14. Synapse formation is regulated by the signaling adaptor GIT1

    OpenAIRE

    Zhang, Huaye; Webb, Donna J.; Asmussen, Hannelore; Horwitz, Alan F.

    2003-01-01

    Dendritic spines in the central nervous system undergo rapid actin-based shape changes, making actin regulators potential modulators of spine morphology and synapse formation. Although several potential regulators and effectors for actin organization have been identified, the mechanisms by which these molecules assemble and localize are not understood. Here we show that the G protein–coupled receptor kinase–interacting protein (GIT)1 serves such a function by targeting actin regulators and lo...

  15. Formation of self-regulation culture of physical education faculty

    Directory of Open Access Journals (Sweden)

    Kudin S.F.

    2016-02-01

    Full Text Available Purpose: to experimentally substantiate effectiveness of pedagogic conditions of self-regulation culture formation of future physical culture teachers. Material: in the research 110 3rd year students of physical education faculty participated. The students were questioned. The level of students’ anxiety was assessed. Results: Implementation of the author’s course in educational process facilitated formation of students’ self-regulation skills and abilities; raises confidence and self estimation; influences positively on functional state. It was found that students acquire ability to consciously observe their own verbal constructs of negative thinking and create positive alternatives. Conclusions: preparing of future physical culture teachers stipulates his (her ability to effectively fulfill professional functioning in the aspect of health preservation. The necessary conditions of self-regulation culture formation are formation of students’ holistic value-meaningful attitude to individual health and health of surrounding people.

  16. The molecular clock mediates leptin-regulated bone formation.

    Science.gov (United States)

    Fu, Loning; Patel, Millan S; Bradley, Allan; Wagner, Erwin F; Karsenty, Gerard

    2005-09-01

    The hormone leptin is a regulator of bone remodeling, a homeostatic function maintaining bone mass constant. Mice lacking molecular-clock components (Per and Cry), or lacking Per genes in osteoblasts, display high bone mass, suggesting that bone remodeling may also be subject to circadian regulation. Moreover, Per-deficient mice experience a paradoxical increase in bone mass following leptin intracerebroventricular infusion. Thus, clock genes may mediate the leptin-dependent sympathetic regulation of bone formation. We show that expression of clock genes in osteoblasts is regulated by the sympathetic nervous system and leptin. Clock genes mediate the antiproliferative function of sympathetic signaling by inhibiting G1 cyclin expression. Partially antagonizing this inhibitory loop, leptin also upregulates AP-1 gene expression, which promotes cyclin D1 expression, osteoblast proliferation, and bone formation. Thus, leptin determines the extent of bone formation by modulating, via sympathetic signaling, osteoblast proliferation through two antagonistic pathways, one of which involves the molecular clock.

  17. Molecular cloud regulated star formation in galaxies

    CERN Document Server

    Booth, C M; Okamoto, T

    2007-01-01

    We describe a numerical implementation of star formation in disk galaxies, in which the conversion of cooling gas to stars in the multiphase interstellar medium is governed by the rate at which molecular clouds are formed and destroyed. In the model, clouds form from thermally unstable ambient gas and get destroyed by feedback from massive stars and thermal conduction. Feedback in the ambient phase cycles gas into a hot galactic fountain or wind. We model the ambient gas hydrodynamically using smoothed particle hydrodynamics (SPH). However, we cannot resolve the Jeans mass in the cold and dense molecular gas and, therefore, represent the cloud phase with ballistic particles that coagulate when colliding. We show that this naturally produces a multiphase medium with cold clouds, a warm disk, hot supernova bubbles and a hot, tenuous halo. Our implementation of this model is based on the Gadget N-Body code. We illustrate the model by evolving an isolated Milky Way-like galaxy and study the properties of a disk f...

  18. A Comparison of the Regulation of Health Professional Boundaries across OECD Countries

    Directory of Open Access Journals (Sweden)

    Ivy Lynn Bourgeault

    2013-06-01

    Full Text Available Increased attention has been paid recently to the issue of the regulation of professional boundaries. In this paper, we undertake an international comparison of the regulation of health professional boundaries across the OECD countries of Canada, the U.S., the U.K. and Australia. Our case studies focus on the inter-professional boundary negotiation between medicine and nursing and the intra-professional boundary negotiation between domestic and internationally trained physicians. Our analysis draws upon the complementary interdisciplinary theoretical perspectives of institutional economics and the concept of professional closure from the sociology of professions. In applying these lenses to the two case studies in these four country contexts, we reveal that there has been a shift in the context of professional regulation towards a more coordinated national approach to licensure. There has also been a broad scale move towards breaking down at least the regulatory barriers to inter-professional collaboration between physicians and nurses which has included the expansion of the scope of nursing practice to take up traditionally exclusive domains of medicine. The seemingly protectionist professional regulatory policies vis-a-vis international medical graduates also seem to be breaking down primarily through government measures. Overall, there has been an increased permeability of professional boundaries both inter-professionally and intra-professionally, and market-oriented systems seem to be in a better position to overcome medical dominance than state-led ones, even though they do not change the main rules of regulation at the macro-level.

  19. The Formation of Boundary Clinopyroxenes and Associated Glass Veins in Type B1 CAIs

    Energy Technology Data Exchange (ETDEWEB)

    Paque, J M; Beckett, J R; Ishii, H A; Toppani, A; Burnett, D S; Teslich, N; Dai, Z R; Bradley, J P

    2008-05-18

    We used focused ion beam thin section preparation and scanning transmission electron microscopy (FIB/STEM) to examine the interfacial region between spinel and host melilite for three spinel grains, two from the mantle and one from the core of an Allende type B1 inclusion, and a second pair of spinel grains from a type B1 inclusion from the Leoville carbonaceous chondrite. The compositions of boundary clinopyroxenes decorating spinel surfaces are generally consistent with those of coarser clinopyroxenes from the same region of the inclusion, suggesting little movement of spinels between mantle and core regions after the formation of boundary clinopyroxenes. The host melilite displays no anomalous compositions near the interface, and anorthite or other late-stage minerals are not observed, suggesting that crystallization of residual liquid was not responsible for the formation of boundary clinopyroxenes. Allende spinels display either direct spinel-melilite contact or an intervening boundary clinopyroxene between the two phases. In the core, boundary clinopyroxene is mantled by a thin (1-2 {micro}m thick) layer of normally zoned (X{sub Ak} increasing away from the melilite-clinopyroxene contact) melilite with X{sub Ak} matching that of the host melilite at the melilite-melilite contact. In the mantle, X{sub Ak} near boundary spinels is constant. Spinels in a Leoville type B1 inclusion are more complex with boundary clinopyroxene, as observed in Allende, but also variable amounts of glass ({approx}1 {micro}m width), secondary calcite, perovskite, and an unknown Mg-, Al-, OH-rich and Ca-, Si-poor crystalline phase that may be a layered double hydrate. Glass compositions are consistent to first order with a precursor consisting mostly of Mg-carpholite or sudoite with some aluminous diopside. One possible scenario of formation for the glass veins is that open system alteration of melilite produced a porous, hydrated aggregate of Mg-carpholite or sudoite + aluminous

  20. Black hole formation in AdS and thermalization on the boundary

    International Nuclear Information System (INIS)

    We investigate black hole formation by a spherically collapsing thin shell of matter in AdS space. This process has been suggested to have a holographic interpretation as thermalization of the CFT on the boundary of the AdS space. The AdS/CFT duality relates the shell in the bulk to an off-equilibrium state of the boundary theory which evolves towards a thermal equilibrium when the shell collapses to a black hole. We use 2-point functions to obtain information about the spectrum of excitations in the off-equilibrium state, and discuss how it characterizes the approach towards thermal equilibrium. The full holographic interpretation of the gravitational collapse would require a kinetic theory of the CFT at strong coupling. We speculate that the kinetic equations should be interpreted as a holographic dual of the equation of motion of the collapsing shell. (author)

  1. Influence of Polyalkylmethacrylate VIIs on Boundary Film Formation,Friction,Wear and Efficiency of Lubricants

    Institute of Scientific and Technical Information of China (English)

    Michael Müller; Hugh Spikes; Alex Tsay

    2006-01-01

    Polyalkylmethacrylates (PAMAs) are well-known as viscosity index improvers and dispersant boosters. This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces, to produce thick, viscous boundary films.These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction of friction. A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry. A range of dispersant and non-dispersant polymethacrylates has been synthesized. The influence of different functionalities, molecular weights and architectures on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting. From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties.Through their ability to form boundary films PAMAs can significantly contribute to reduce wear in engine, gear and hydraulic lubrication. As a consequence of their viscometric and tribological performance PAMAs can furthermore improve fuel and energy efficiency in different, namely engine and hydraulic applications.Extensive work is currently conducted in the lubricant industry to develop engine oils with lower sulfur, phosphorus and metal content (low SAPS) and to optimize their frictional properties through the use of friction modifiers or synthetic base stocks. We have investigated the contribution of PAMA viscosity index improvers and boosters to improve fuel economy and to reduce wear levels. This paper reports our efforts to develop a new range of PAMAs that have been optimized in terms of composition, architecture, molecular weight and functionality and which can be used in low viscosity, low SAPS formulations to help meet the stringent requirements of modern engine oils.

  2. On the Formation Mechanisms of Artificially Generated High Reynolds Number Turbulent Boundary Layers

    Science.gov (United States)

    Rodríguez-López, Eduardo; Bruce, Paul J. K.; Buxton, Oliver R. H.

    2016-08-01

    We investigate the evolution of an artificially thick turbulent boundary layer generated by two families of small obstacles (divided into uniform and non-uniform wall normal distributions of blockage). One- and two-point velocity measurements using constant temperature anemometry show that the canonical behaviour of a boundary layer is recovered after an adaptation region downstream of the trips presenting 150~% higher momentum thickness (or equivalently, Reynolds number) than the natural case for the same downstream distance (x≈ 3 m). The effect of the degree of immersion of the trips for h/δ ≳ 1 is shown to play a secondary role. The one-point diagnostic quantities used to assess the degree of recovery of the canonical properties are the friction coefficient (representative of the inner motions), the shape factor and wake parameter (representative of the wake regions); they provide a severe test to be applied to artificially generated boundary layers. Simultaneous two-point velocity measurements of both spanwise and wall-normal correlations and the modulation of inner velocity by the outer structures show that there are two different formation mechanisms for the boundary layer. The trips with high aspect ratio and uniform distributed blockage leave the inner motions of the boundary layer relatively undisturbed, which subsequently drive the mixing of the obstacles' wake with the wall-bounded flow (wall-driven). In contrast, the low aspect-ratio trips with non-uniform blockage destroy the inner structures, which are then re-formed further downstream under the influence of the wake of the trips (wake-driven).

  3. Characterizing the formation and regeneration of hairpin vortices in a laminar boundary layer

    Science.gov (United States)

    Sabatino, Daniel R.; Maharjan, Rijan

    2015-12-01

    A free surface water channel is used to study hairpin vortex formation created by fluid injection through a narrow slot into a laminar boundary layer. Particle image velocimetry flow-field measurements of injections into quiescent cross-flow conditions confirm that elongated ring vortices are produced with a nondimensionalized circulation strength that is approximately linear with formation time. Unlike circular ring vortices, a limiting strength is not observed at a nondimensional formation time of 4 due to the proximity of the counter-rotating vortex pair. Identical injections are made into a laminar boundary layer at different free-stream velocities and streamwise slot positions (485 ≤ Reδ∗ ≤ 584) with average injection velocity ratios between 0.08 and 0.16. Visualizations indicate that the shear layer between the low x-momentum injected fluid and the boundary layer creates a Kelvin-Helmholtz instability that forms the hairpin vortex head which then monotonically decreases in circulation strength with downstream distance. A similar process can form, or regenerate, a secondary hairpin vortex upstream of the primary vortex with a circulation strength of the head that is comparable to the strength of the primary head at the time of regeneration. However, the legs of the primary vortex continue to strengthen up to regeneration. The peak circulation in the legs is not directly correlated to the strength of the original elongated ring vortex. However, when the circulation is scaled with the injection momentum ratio it is linearly related to scaled injection time. It is proposed that the injection momentum ratio and nondimensionalized injection time based on the wall normal penetration time can be used to identify threshold conditions which produce a secondary vortex. It is suggested that this criterion may be used to identify the minimum strength of flow structures that would be capable of regeneration and thus transition initiation.

  4. Prostaglandins temporally regulate cytoplasmic actin bundle formation during Drosophila oogenesis

    OpenAIRE

    Spracklen, Andrew J.; Kelpsch, Daniel J.; Chen, Xiang; Spracklen, Cassandra N.; Tootle, Tina L.

    2014-01-01

    Prostaglandins (PGs)—lipid signals produced downstream of cyclooxygenase (COX) enzymes—regulate actin dynamics in cell culture and platelets, but their roles during development are largely unknown. Here we define a new role for Pxt, the Drosophila COX-like enzyme, in regulating the actin cytoskeleton—temporal restriction of actin remodeling during oogenesis. PGs are required for actin filament bundle formation during stage 10B (S10B). In addition, loss of Pxt results in extensive early actin ...

  5. Misorientation effect of grain boundary on the formation of discontinuous precipitation in second and third generation single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Yu Zhengrong

    2014-01-01

    Full Text Available [001] tilt artificial grain boundaries of Ni-based single crystal superalloys CMSX-4 and DD10 have been prepared by self-diffusion bonding. The microstructural stability of 0 ∼ 30∘ artificial grain boundaries have been investigated after heat treatment at 1100 ∘C for 0 ∼ 300 h. TCP phases and cellular colony developed on boundaries are related to misorientation angle of the bonded boundaries of DD10 and DD10 alloys as well as the bonded boundaries of CMSX-4 and DD10 alloys. The heterogeneous nucleation of TCP phase, enveloped by γ′ film, occurred along 15∘ and 20∘ boundaries. Discontinuous Precipitation (DP reaction occurred along high misorientation angle (20∘∼ 30∘ boundaries. However, no TCP phase formation existed along grain boundaries with different misorientation angles in CMSX-4/CMSX-4 bonded alloys as well as for a 0∘ boundary in DD10/DD10 and CMSX-4/DD10 bonded alloys. The current study clearly suggests that grain boundary precipitation and its morphology were influenced by the misorientation angle of grain boundary and the content of refractory elements in alloy.

  6. Leptin regulates bone formation via the sympathetic nervous system

    Science.gov (United States)

    Takeda, Shu; Elefteriou, Florent; Levasseur, Regis; Liu, Xiuyun; Zhao, Liping; Parker, Keith L.; Armstrong, Dawna; Ducy, Patricia; Karsenty, Gerard

    2002-01-01

    We previously showed that leptin inhibits bone formation by an undefined mechanism. Here, we show that hypothalamic leptin-dependent antiosteogenic and anorexigenic networks differ, and that the peripheral mediators of leptin antiosteogenic function appear to be neuronal. Neuropeptides mediating leptin anorexigenic function do not affect bone formation. Leptin deficiency results in low sympathetic tone, and genetic or pharmacological ablation of adrenergic signaling leads to a leptin-resistant high bone mass. beta-adrenergic receptors on osteoblasts regulate their proliferation, and a beta-adrenergic agonist decreases bone mass in leptin-deficient and wild-type mice while a beta-adrenergic antagonist increases bone mass in wild-type and ovariectomized mice. None of these manipulations affects body weight. This study demonstrates a leptin-dependent neuronal regulation of bone formation with potential therapeutic implications for osteoporosis.

  7. Inside-Out Planet Formation. III. Planet-disk interaction at the dead zone inner boundary

    CERN Document Server

    Hu, Xiao; Tan, Jonathan C; Chatterjee, Sourav

    2015-01-01

    The Kepler mission has discovered more than 4000 exoplanet candidates. Many are in systems with tightly packed inner planets. Inside-Out Planet Formation (IOPF) has been proposed to explain these systems. It involves sequential in situ planet formation at the local pressure maximum of a retreating dead zone inner boundary (DZIB). Pebbles accumulate at this pressure trap, which builds up a ring, and then a planet. The planet is expected to grow until it opens a gap, which helps to both truncate pebble accretion and induce DZIB retreat that sets the location of formation of the next planet. This simple scenario may be modified if the planet migrates significantly from its formation location. Thus planet-disk interactions play a crucial role in the IOPF scenario. We present numerical simulations that first assess migration of planets of various masses that are forming at the DZIB of an active accretion disk, where the effective viscosity rapidly increases in the radially inward direction. We find that the disk's...

  8. DELLA proteins regulate arbuscule formation in arbuscular mycorrhizal symbiosis.

    Science.gov (United States)

    Floss, Daniela S; Levy, Julien G; Lévesque-Tremblay, Véronique; Pumplin, Nathan; Harrison, Maria J

    2013-12-17

    Most flowering plants are able to form endosymbioses with arbuscular mycorrhizal fungi. In this mutualistic association, the fungus colonizes the root cortex and establishes elaborately branched hyphae, called arbuscules, within the cortical cells. Arbuscule development requires the cellular reorganization of both symbionts, and the resulting symbiotic interface functions in nutrient exchange. A plant symbiosis signaling pathway controls the development of the symbiosis. Several components of the pathway have been identified, but transcriptional regulators that control downstream pathways for arbuscule formation are still unknown. Here we show that DELLA proteins, which are repressors of gibberellic acid (GA) signaling and function at the nexus of several signaling pathways, are required for arbuscule formation. Arbuscule formation is severely impaired in a Medicago truncatula Mtdella1/Mtdella2 double mutant; GA treatment of wild-type roots phenocopies the della double mutant, and a dominant DELLA protein (della1-Δ18) enables arbuscule formation in the presence of GA. Ectopic expression of della1-Δ18 suggests that DELLA activity in the vascular tissue and endodermis is sufficient to enable arbuscule formation in the inner cortical cells. In addition, expression of della1-Δ18 restores arbuscule formation in the symbiosis signaling pathway mutant cyclops/ipd3, indicating an intersection between DELLA and symbiosis signaling for arbuscule formation. GA signaling also influences arbuscule formation in monocots, and a Green Revolution wheat variety carrying dominant DELLA alleles shows enhanced colonization but a limited growth response to arbuscular mycorrhizal symbiosis.

  9. Instantons near a tachyonic top in anti de Sitter and the no-boundary regulator

    CERN Document Server

    Lee, Bum-Hoon; Ro, Daeho; Yeom, Dong-han

    2014-01-01

    We investigate instantons near the tachyonic top in the anti de Sitter (AdS) background. If the mass around the hill-top is above the Breitenlohner-Freedman (BF) bound, then the top is classically stable. When the BF bound is satisfied, it is already known that there can exist instantons with a non-zero probability, though fine-tunings of the potential are required. On the other hand, we may consider the possibility to obtain instantons with a non-zero probability for more natural shape of potentials. We found that the no-boundary regulator is useful to assign a non-zero probability for general instantons near the tachyonic top within a consistent framework. To use the no-boundary regulator, we need to introduce the complexification of fields. One interesting feature is that, for these AdS instantons, the classicality may not be satisfied after the Wick rotation and hence after the nucleation. This magnifies a novel difference between dS and AdS; a semi-classical boundary observer in AdS may notice the disper...

  10. Chromatin boundary elements organize genomic architecture and developmental gene regulation in Drosophila Hox clusters

    Science.gov (United States)

    Ma, Zhibo; Li, Mo; Roy, Sharmila; Liu, Kevin J; Romine, Matthew L; Lane, Derrick C; Patel, Sapna K; Cai, Haini N

    2016-01-01

    The three-dimensional (3D) organization of the eukaryotic genome is critical for its proper function. Evidence suggests that extensive chromatin loops form the building blocks of the genomic architecture, separating genes and gene clusters into distinct functional domains. These loops are anchored in part by a special type of DNA elements called chromatin boundary elements (CBEs). CBEs were originally found to insulate neighboring genes by blocking influences of transcriptional enhancers or the spread of silent chromatin. However, recent results show that chromatin loops can also play a positive role in gene regulation by looping out intervening DNA and “delivering” remote enhancers to gene promoters. In addition, studies from human and model organisms indicate that the configuration of chromatin loops, many of which are tethered by CBEs, is dynamically regulated during cell differentiation. In particular, a recent work by Li et al has shown that the SF1 boundary, located in the Drosophila Hox cluster, regulates local genes by tethering different subsets of chromatin loops: One subset enclose a neighboring gene ftz, limiting its access by the surrounding Scr enhancers and restrict the spread of repressive histones during early embryogenesis; and the other loops subdivide the Scr regulatory region into independent domains of enhancer accessibility. The enhancer-blocking activity of these CBE elements varies greatly in strength and tissue distribution. Further, tandem pairing of SF1 and SF2 facilitate the bypass of distal enhancers in transgenic flies, providing a mechanism for endogenous enhancers to circumvent genomic interruptions resulting from chromosomal rearrangement. This study demonstrates how a network of chromatin boundaries, centrally organized by SF1, can remodel the 3D genome to facilitate gene regulation during development.

  11. Chromatin boundary elements organize genomic architecture and developmental gene regulation in Drosophila Hox clusters.

    Science.gov (United States)

    Ma, Zhibo; Li, Mo; Roy, Sharmila; Liu, Kevin J; Romine, Matthew L; Lane, Derrick C; Patel, Sapna K; Cai, Haini N

    2016-08-26

    The three-dimensional (3D) organization of the eukaryotic genome is critical for its proper function. Evidence suggests that extensive chromatin loops form the building blocks of the genomic architecture, separating genes and gene clusters into distinct functional domains. These loops are anchored in part by a special type of DNA elements called chromatin boundary elements (CBEs). CBEs were originally found to insulate neighboring genes by blocking influences of transcriptional enhancers or the spread of silent chromatin. However, recent results show that chromatin loops can also play a positive role in gene regulation by looping out intervening DNA and "delivering" remote enhancers to gene promoters. In addition, studies from human and model organisms indicate that the configuration of chromatin loops, many of which are tethered by CBEs, is dynamically regulated during cell differentiation. In particular, a recent work by Li et al has shown that the SF1 boundary, located in the Drosophila Hox cluster, regulates local genes by tethering different subsets of chromatin loops: One subset enclose a neighboring gene ftz, limiting its access by the surrounding Scr enhancers and restrict the spread of repressive histones during early embryogenesis; and the other loops subdivide the Scr regulatory region into independent domains of enhancer accessibility. The enhancer-blocking activity of these CBE elements varies greatly in strength and tissue distribution. Further, tandem pairing of SF1 and SF2 facilitate the bypass of distal enhancers in transgenic flies, providing a mechanism for endogenous enhancers to circumvent genomic interruptions resulting from chromosomal rearrangement. This study demonstrates how a network of chromatin boundaries, centrally organized by SF1, can remodel the 3D genome to facilitate gene regulation during development. PMID:27621770

  12. Formation of magnetic filaments at the boundaries of the magnetospheres of solar system planets

    International Nuclear Information System (INIS)

    The theory of localized spontaneous reconnection at the boundaries of the magnetospheres of solar-system planets with strong intrinsic magnetic field is given in the paper. Such forms of reconnection (flux transfer events - FTE) resulting in formation of magnetic filaments are observed by sattelites near the magnetosphgeres of Mercury, Earth and Jupiter. The physical factors controlling the temporal and spatial scales of this phenomenon in dependence on the distance from the Sun (the parameters of the solar wind) and the planetary magnetic dipole moment are discussed. the theoretical estimates of characteristic diameters of magnetic filaments λE ∼ 5000 km, λM ∼ 500 km, λJ ∼ 13000 km for the Earth, Mercury and Jupiter agree satisfactorily with the experimental data. In conclusion, the typical FTE parameters for Saturn and some other astrophysical objects are evaluated

  13. Stochastic Structural Stability Theory applied to roll/streak formation in boundary layer shear flow

    CERN Document Server

    Farrell, Brian F

    2010-01-01

    Stochastic Structural Stability Theory (SSST) provides an autonomous, deterministic, nonlinear dynamical system for evolving the statistical mean state of a turbulent system. In this work SSST is applied to the problem of understanding the formation of the roll/streak structures that arise from free-stream turbulence (FST) and are associated with bypass transition in boundary layers. Roll structures in the cross-stream/spanwise plane and associated streamwise streaks are shown to arise as a linear instability of interaction between the FST and the mean flow. In this interaction incoherent Reynolds stresses arising from FST are organized by perturbation streamwise streaks to coherently force perturbation rolls giving rise to an amplification of the streamwise streak perturbation and through this feedback to an instability of the combined roll/streak/turbulence complex. The dominant turbulent perturbation structures involved in supporting the roll/streak/turbulence complex instability are non-normal optimal per...

  14. Vesicle Size Regulates Nanotube Formation in the Cell

    OpenAIRE

    Qian Peter Su; Wanqing Du; Qinghua Ji; Boxin Xue; Dong Jiang; Yueyao Zhu; Jizhong Lou; Li Yu; Yujie Sun

    2016-01-01

    Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro st...

  15. Formation and Regulation of Adaptive Response in Nematode Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Y.-L. Zhao

    2012-01-01

    Full Text Available All organisms respond to environmental stresses (e.g., heavy metal, heat, UV irradiation, hyperoxia, food limitation, etc. with coordinated adjustments in order to deal with the consequences and/or injuries caused by the severe stress. The nematode Caenorhabditis elegans often exerts adaptive responses if preconditioned with low concentrations of agents or stressor. In C. elegans, three types of adaptive responses can be formed: hormesis, cross-adaptation, and dietary restriction. Several factors influence the formation of adaptive responses in nematodes, and some mechanisms can explain their response formation. In particular, antioxidation system, heat-shock proteins, metallothioneins, glutathione, signaling transduction, and metabolic signals may play important roles in regulating the formation of adaptive responses. In this paper, we summarize the published evidence demonstrating that several types of adaptive responses have converged in C. elegans and discussed some possible alternative theories explaining the adaptive response control.

  16. The boundary layer characteristics in the heavy fog formation process over Beijing and its adjacent areas

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Guangzhi; BIAN; Lingeng; WANG; Jizhi; YANG; Yuanqi

    2005-01-01

    By utilizing the Atmospheric Boundary Layer (ABL) observational data made available from the project "973" under the auspices of the Ministry of Science and Technology of the People's Republic of China - entitled the Beijing City Air Pollution Observation Field Experiment (BECAPEX), including the measurements by a wind profiler, captive airships, tower-based boundary layer wind and temperature gradient observational instruments (ultrasonic anemometers and electronic thermometers), air composition samplers, conventional upper-air, surface and Automatic Weather Stations (AWS) observations, this paper herewith analyzes, in a comprehensive manner, the occurrence of a heavy fog event over Beijing in February 2001, including its formation, development, persistence, dynamic and thermodynamic features as well as evolving stratification structures within the boundary layer at different stages. The results suggested: (i) as a typical case of urban heavy fog, before the fog onset over Beijing, a temperature inversion existed in the lower atmosphere, the smokes and the pollutants like SO2 and NO2 had been accumulated at a lower level. Proceeding the fog event, with the increase of SO2 and NO2 concentrations, condensability increased sharply. On the contrary, during the fog process, with increasing condensability, SO2 and NO2 concentrations decreased. This indicated that, acting as condensation nucleus, these accumulated pollutants were playing a key role in catalyzing the fog condensation. (ii) By analyzing mean gradient-, pulsation- and turbulence-distribution patterns derived from the wind measurements taken by the aforementioned tower-based instruments, they all indicated that about 10 hours before the fog onset, a signal foretelling potential strong disturbances in the lower boundary layer was detected, and a significant rise of both mean and disturbance kinetic energies was observed, revealing that the low-level wind shear was strengthened before the fog onset

  17. Notch1-Dll4 signalling and mechanical force regulate leader cell formation during collective cell migration.

    Science.gov (United States)

    Riahi, Reza; Sun, Jian; Wang, Shue; Long, Min; Zhang, Donna D; Wong, Pak Kin

    2015-03-13

    At the onset of collective cell migration, a subset of cells within an initially homogenous population acquires a distinct 'leader' phenotype with characteristic morphology and motility. However, the factors driving the leader cell formation as well as the mechanisms regulating leader cell density during the migration process remain to be determined. Here we use single-cell gene expression analysis and computational modelling to show that the leader cell identity is dynamically regulated by Dll4 signalling through both Notch1 and cellular stress in a migrating epithelium. Time-lapse microscopy reveals that Dll4 is induced in leader cells after the creation of the cell-free region and leader cells are regulated via Notch1-Dll4 lateral inhibition. Furthermore, mechanical stress inhibits Dll4 expression and leader cell formation in the monolayer. Collectively, our findings suggest that a reduction of mechanical force near the boundary promotes Notch1-Dll4 signalling to dynamically regulate the density of leader cells during collective cell migration.

  18. Regulation of biofilm formation in Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Simm, Roger; Ahmad, Irfan; Rhen, Mikael; Le Guyon, Soazig; Römling, Ute

    2014-01-01

    In animals, plants and the environment, Salmonella enterica serovar Typhimurium forms the red dry and rough (rdar) biofilm characterized by extracellular matrix components curli and cellulose. With complex expression control by at least ten transcription factors, the bistably expressed orphan response regulator CsgD directs rdar morphotype development. CsgD expression is an integral part of the Hfq regulon and the complex cyclic diguanosine monophosphate signaling network partially controlled by the global RNA-binding protein CsrA. Cell wall turnover and the periplasmic redox status regulate csgD expression on a post-transcriptional level by unknown mechanisms. Furthermore, phosphorylation of CsgD is a potential inactivation and degradation signal in biofilm dissolution. Including complex incoherent feed-forward loops, regulation of biofilm formation versus motility and virulence is of recognized complexity.

  19. Boundary layer new particle formation over East Antarctic sea ice – possible Hg-driven nucleation?

    Directory of Open Access Journals (Sweden)

    R. S. Humphries

    2015-12-01

    Full Text Available Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on the only day to exhibit extended periods of global irradiance in excess of 600 W m−2. Within the single air mass influencing the measurements, number concentrations of particles larger than 3 nm (CN3 reached almost 7700 cm−3 within a few hours of clouds clearing, and grew at rates of 5.6 nm h−1. Formation rates of 3 nm particles were in the range of those measured at other Antarctic locations at 0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into the nucleation chemistry found that there were insufficient precursor concentrations for known halogen or organic chemistry to explain the nucleation event. Modelling studies utilising known sulfuric acid nucleation schemes could not simultaneously reproduce both particle formation or growth rates. Surprising correlations with total gaseous mercury (TGM were found that, together with other data, suggest a mercury-driven photochemical nucleation mechanism may be responsible for aerosol nucleation. Given the very low vapour pressures of the mercury species involved, this nucleation chemistry is likely only possible where pre-existing aerosol concentrations are low and both TGM concentrations and solar radiation levels are relatively high (∼ 1.5 ng m−3 and ≥ 600 W m−2, respectively, such as those observed in the Antarctic sea ice boundary layer in this study or in the global free troposphere, particularly in the Northern Hemisphere.

  20. Quorum-sensing regulates biofilm formation in Vibrio scophthalmi

    Directory of Open Access Journals (Sweden)

    García-Aljaro Cristina

    2012-12-01

    Full Text Available Abstract Background In a previous study, we demonstrated that Vibrio scophthalmi, the most abundant Vibrio species among the marine aerobic or facultatively anaerobic bacteria inhabiting the intestinal tract of healthy cultured turbot (Scophthalmus maximus, contains at least two quorum-sensing circuits involving two types of signal molecules (a 3-hydroxy-dodecanoyl-homoserine lactone and the universal autoinducer 2 encoded by luxS. The purpose of this study was to investigate the functions regulated by these quorum sensing circuits in this vibrio by constructing mutants for the genes involved in these circuits. Results The presence of a homologue to the Vibrio harveyi luxR gene encoding a main transcriptional regulator, whose expression is modulated by quorum–sensing signal molecules in other vibrios, was detected and sequenced. The V. scophthalmi LuxR protein displayed a maximum amino acid identity of 82% with SmcR, the LuxR homologue found in Vibrio vulnificus. luxR and luxS null mutants were constructed and their phenotype analysed. Both mutants displayed reduced biofilm formation in vitro as well as differences in membrane protein expression by mass-spectrometry analysis. Additionally, a recombinant strain of V. scophthalmi carrying the lactonase AiiA from Bacillus cereus, which causes hydrolysis of acyl homoserine lactones, was included in the study. Conclusions V. scophthalmi shares two quorum sensing circuits, including the main transcriptional regulator luxR, with some pathogenic vibrios such as V. harveyi and V. anguillarum. However, contrary to these pathogenic vibrios no virulence factors (such as protease production were found to be quorum sensing regulated in this bacterium. Noteworthy, biofilm formation was altered in luxS and luxR mutants. In these mutants a different expression profile of membrane proteins were observed with respect to the wild type strain suggesting that quorum sensing could play a role in the regulation of

  1. Vesicle Size Regulates Nanotube Formation in the Cell

    Science.gov (United States)

    Su, Qian Peter; Du, Wanqing; Ji, Qinghua; Xue, Boxin; Jiang, Dong; Zhu, Yueyao; Lou, Jizhong; Yu, Li; Sun, Yujie

    2016-01-01

    Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro studies also lack physiological relevance. Here, we use lysosomes and autolysosomes, whose sizes range between 100 nm and 1 μm, as model systems to study the size effects on nanotube formation both in vivo and in vitro. Single molecule observations indicate that driven by kinesin motors, small vesicles (100–200 nm) are mainly transported along the tracks while a remarkable portion of large vesicles (500–1000 nm) form nanotubes. This size effect is further confirmed by in vitro reconstitution assays on liposomes and purified lysosomes and autolysosomes. We also apply Atomic Force Microscopy (AFM) to measure the initiation force for nanotube formation. These results suggest that the size-dependence may be one of the mechanisms for cells to regulate cellular processes involving membrane-deformation, such as the timing of tubulation-mediated vesicle recycling. PMID:27052881

  2. Vesicle Size Regulates Nanotube Formation in the Cell.

    Science.gov (United States)

    Su, Qian Peter; Du, Wanqing; Ji, Qinghua; Xue, Boxin; Jiang, Dong; Zhu, Yueyao; Lou, Jizhong; Yu, Li; Sun, Yujie

    2016-04-07

    Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro studies also lack physiological relevance. Here, we use lysosomes and autolysosomes, whose sizes range between 100 nm and 1 μm, as model systems to study the size effects on nanotube formation both in vivo and in vitro. Single molecule observations indicate that driven by kinesin motors, small vesicles (100-200 nm) are mainly transported along the tracks while a remarkable portion of large vesicles (500-1000 nm) form nanotubes. This size effect is further confirmed by in vitro reconstitution assays on liposomes and purified lysosomes and autolysosomes. We also apply Atomic Force Microscopy (AFM) to measure the initiation force for nanotube formation. These results suggest that the size-dependence may be one of the mechanisms for cells to regulate cellular processes involving membrane-deformation, such as the timing of tubulation-mediated vesicle recycling.

  3. Prostaglandins temporally regulate cytoplasmic actin bundle formation during Drosophila oogenesis.

    Science.gov (United States)

    Spracklen, Andrew J; Kelpsch, Daniel J; Chen, Xiang; Spracklen, Cassandra N; Tootle, Tina L

    2014-02-01

    Prostaglandins (PGs)--lipid signals produced downstream of cyclooxygenase (COX) enzymes--regulate actin dynamics in cell culture and platelets, but their roles during development are largely unknown. Here we define a new role for Pxt, the Drosophila COX-like enzyme, in regulating the actin cytoskeleton--temporal restriction of actin remodeling during oogenesis. PGs are required for actin filament bundle formation during stage 10B (S10B). In addition, loss of Pxt results in extensive early actin remodeling, including actin filaments and aggregates, within the posterior nurse cells of S9 follicles; wild-type follicles exhibit similar structures at a low frequency. Hu li tai shao (Hts-RC) and Villin (Quail), an actin bundler, localize to all early actin structures, whereas Enabled (Ena), an actin elongation factor, preferentially localizes to those in pxt mutants. Reduced Ena levels strongly suppress early actin remodeling in pxt mutants. Furthermore, loss of Pxt results in reduced Ena localization to the sites of bundle formation during S10B. Together these data lead to a model in which PGs temporally regulate actin remodeling during Drosophila oogenesis by controlling Ena localization/activity, such that in S9, PG signaling inhibits, whereas at S10B, it promotes Ena-dependent actin remodeling.

  4. Norms as The Formation of Boundary and Place in Madurase Dwellings of Madura-Indonesia

    Directory of Open Access Journals (Sweden)

    Lintu Tulistyantoro

    2016-06-01

    Full Text Available This paper discusses the result of exploring the understanding of Madurese people live in the island of Madura, a part of East Java, Indonesia on the concept of place and boundary. The discussion was considered about spaces and practices that have been created, adopted, or invoked by the Madurese for their specific purposes. To understand the concept of place, must deal with the meaning of boundary. Boundary in Architecture means the distinguisher between an area with the other area. Boundary not only can separate place, but it can also communicate two different places. The form of boundary has many types; it can be visible or non-visible and physical or non-physical. An expression of boundary in shaping the place can actually be determined by the cultural factor. One example of boundary by the cultural factor is norm in culture. The norms relating with dignity have boundary and place that are so powerful and clear. Boundary by the norms has a strong impact to the place shaping. Therefore, norms have become one element to shape a place. The norms can be non-physical but it has a very powerful boundary of place. The consequences of the norms are the boundary of the Madurese dwelling has a hierarchy, which is a very clear and strong boundary.

  5. Signaling by bone morphogenetic proteins directs formation of an ectodermal signaling center that regulates craniofacial development.

    Science.gov (United States)

    Foppiano, Silvia; Hu, Diane; Marcucio, Ralph S

    2007-12-01

    We previously described a signaling center, the Frontonasal Ectodermal Zone (FEZ) that regulates growth and patterning of the frontonasal process (FNP). The FEZ is comprised of FNP ectoderm flanking a boundary between Sonic hedgehog (Shh) and Fibroblast growth factor 8 (Fgf8) expression domains. Our objective was to examine BMP signaling during formation of the FEZ. We blocked BMP signaling throughout the FNP prior to FEZ formation by infecting chick embryos at stage 10 (HH10) with a replication-competent avian retrovirus encoding the BMP antagonist Noggin. We assessed gene expression patterns in the FNP 72 h after infection (approximately HH22) and observed that Shh expression was reduced or absent. In the mesenchyme, we observed that Bmp2 transcripts were absent while the Bmp4 expression domain was expanded proximally. In addition to the molecular changes, infected embryos also exhibited facial malformations at 72 and 96 h after infection suggesting that the FEZ did not form. Our data indicate that reduced cell proliferation, but not apoptosis, in the mesenchyme contributed to the phenotype that we observed. Additionally, adding exogenous SHH into the mesenchyme of RCAS-Noggin-infected embryos did not restore Bmp2 and Bmp4 to a normal pattern of expression. These data indicate that BMP signaling mediates interactions between tissues in the FNP that regulate FEZ formation; and that the correct pattern of Bmp2 and Bmp4, but not Bmp7, expression in the FNP mesenchyme requires signaling by the BMP pathway.

  6. Homeostatic regulation of meiotic DSB formation by ATM/ATR

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J., E-mail: m.neale@sussex.ac.uk

    2014-11-15

    Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.

  7. Soil-plant-atmosphere conditions regulating convective cloud formation above southeastern US pine plantations.

    Science.gov (United States)

    Manoli, Gabriele; Domec, Jean-Christophe; Novick, Kimberly; Oishi, Andrew Christopher; Noormets, Asko; Marani, Marco; Katul, Gabriel

    2016-06-01

    Loblolly pine trees (Pinus taeda L.) occupy more than 20% of the forested area in the southern United States, represent more than 50% of the standing pine volume in this region, and remove from the atmosphere about 500 g C m-2 per year through net ecosystem exchange. Hence, their significance as a major regional carbon sink can hardly be disputed. What is disputed is whether the proliferation of young plantations replacing old forest in the southern United States will alter key aspects of the hydrologic cycle, including convective rainfall, which is the focus of the present work. Ecosystem fluxes of sensible (Hs) and latent heat (LE) and large-scale, slowly evolving free atmospheric temperature and water vapor content are known to be first-order controls on the formation of convective clouds in the atmospheric boundary layer. These controlling processes are here described by a zero-order analytical model aimed at assessing how plantations of different ages may regulate the persistence and transition of the atmospheric system between cloudy and cloudless conditions. Using the analytical model together with field observations, the roles of ecosystem Hs and LE on convective cloud formation are explored relative to the entrainment of heat and moisture from the free atmosphere. Our results demonstrate that cloudy-cloudless regimes at the land surface are regulated by a nonlinear relation between the Bowen ratio Bo=Hs/LE and root-zone soil water content, suggesting that young/mature pines ecosystems have the ability to recirculate available water (through rainfall predisposition mechanisms). Such nonlinearity was not detected in a much older pine stand, suggesting a higher tolerance to drought but a limited control on boundary layer dynamics. These results enable the generation of hypotheses about the impacts on convective cloud formation driven by afforestation/deforestation and groundwater depletion projected to increase following increased human population in the

  8. Vinculin-dependent Cadherin mechanosensing regulates efficient epithelial barrier formation

    Directory of Open Access Journals (Sweden)

    Floor Twiss

    2012-09-01

    Proper regulation of the formation and stabilization of epithelial cell–cell adhesion is crucial in embryonic morphogenesis and tissue repair processes. Defects in this process lead to organ malformation and defective epithelial barrier function. A combination of chemical and mechanical cues is used by cells to drive this process. We have investigated the role of the actomyosin cytoskeleton and its connection to cell–cell junction complexes in the formation of an epithelial barrier in MDCK cells. We find that the E-cadherin complex is sufficient to mediate a functional link between cell–cell contacts and the actomyosin cytoskeleton. This link involves the actin binding capacity of α-catenin and the recruitment of the mechanosensitive protein Vinculin to tensile, punctate cell–cell junctions that connect to radial F-actin bundles, which we name Focal Adherens Junctions (FAJ. When cell–cell adhesions mature, these FAJs disappear and linear junctions are formed that do not contain Vinculin. The rapid phase of barrier establishment (as measured by Trans Epithelial Electrical Resistance (TER correlates with the presence of FAJs. Moreover, the rate of barrier establishment is delayed when actomyosin contraction is blocked or when Vinculin recruitment to the Cadherin complex is prevented. Enhanced presence of Vinculin increases the rate of barrier formation. We conclude that E-cadherin-based FAJs connect forming cell–cell adhesions to the contractile actomyosin cytoskeleton. These specialized junctions are sites of Cadherin mechanosensing, which, through the recruitment of Vinculin, is a driving force in epithelial barrier formation.

  9. Laminin 5 regulates polycystic kidney cell proliferation and cyst formation.

    Science.gov (United States)

    Joly, Dominique; Berissi, Sophie; Bertrand, Amélie; Strehl, Laetitia; Patey, Natacha; Knebelmann, Bertrand

    2006-09-29

    Renal cyst formation is the hallmark of autosomal dominant polycystic kidney disease (ADPKD). ADPKD cyst-lining cells have an increased proliferation rate and are surrounded by an abnormal extracellular matrix (ECM). We have previously shown that Laminin 5 (Ln-5, a alpha(3)beta(3)gamma(2) trimer) is aberrantly expressed in the pericystic ECM of ADPKD kidneys. We report that ADPKD cells in primary cultures produce and secrete Ln-5 that is incorporated to the pericystic ECM in an in vitro model of cystogenesis. In monolayers, purified Ln-5 induces ERK activation and proliferation of ADPKD cells, whereas upon epidermal growth factor stimulation blocking endogenously produced Ln-5 with anti-gamma(2) chain antibody reduces the sustained ERK activation and inhibits proliferation. In three-dimensional gel culture, addition of purified Ln-5 stimulates cell proliferation and cyst formation, whereas blocking endogenous Ln-5 strongly inhibits cyst formation. Ligation of alpha(6)beta(4) integrin, a major Ln-5 receptor aberrantly expressed by ADPKD cells, induces beta(4) integrin phosphorylation, ERK activation, cell proliferation, and cyst formation. These findings indicate that Ln-5 is an important regulator of ADPKD cell proliferation and cystogenesis and suggest that Ln-5 gamma(2) chain and Ln-5-alpha(6)beta(4) integrin interaction both contribute to these phenotypic changes. PMID:16870608

  10. Circadian rhythms and memory formation: regulation by chromatin remodeling.

    Science.gov (United States)

    Sahar, Saurabh; Sassone-Corsi, Paolo

    2012-01-01

    Epigenetic changes, such as DNA methylation or histone modification, can remodel the chromatin and regulate gene expression. Remodeling of chromatin provides an efficient mechanism of transducing signals, such as light or nutrient availability, to regulate gene expression. CLOCK:BMAL1 mediated activation of clock-controlled genes (CCGs) is coupled to circadian changes in histone modification at their promoters. Several chromatin modifiers, such as the deacetylases SIRT1 and HDAC3 or methyltransferase MLL1, have been shown to be recruited to the promoters of the CCGs in a circadian manner. Interestingly, the central element of the core clock machinery, the transcription factor CLOCK, also possesses histone acetyltransferase activity. Rhythmic expression of the CCGs is abolished in the absence of these chromatin modifiers. Recent research has demonstrated that chromatin remodeling is at the cross-roads of circadian rhythms and regulation of metabolism and aging. It would be of interest to identify if similar pathways exist in the epigenetic regulation of memory formation. PMID:22470318

  11. Circadian Rhythms and Memory Formation: Regulation by Chromatin Remodeling

    Directory of Open Access Journals (Sweden)

    Saurabh eSahar

    2012-03-01

    Full Text Available Epigenetic changes, such as DNA methylation or histone modification, can remodel the chromatin and regulate gene expression. Remodeling of chromatin provides an efficient mechanism of transducing signals, such as light or nutrient availability, to regulate gene expression. CLOCK:BMAL1 mediated activation of clock-controlled genes (CCGs is coupled to circadian changes in histone modification at their promoters. Several chromatin modifiers, such as the deacetylases SIRT1 and HDAC3 or methyltransferase MLL1, have been shown to be recruited to the promoters of the CCGs in a circadian manner. Interestingly, the central element of the core clock machinery, the transcription factor CLOCK, also possesses histone acetyltransferase activity. Rhythmic expression of the CCGs is abolished in the absence of these chromatin modifiers. Recent research has demonstrated that chromatin remodeling is at the cross-roads of circadian rhythms and regulation of metabolism and aging. It would be of interest to identify if similar pathways exist in the epigenetic regulation of memory formation.

  12. How stellar feedback simultaneously regulates star formation and drives outflows

    CERN Document Server

    Hayward, Christopher C

    2015-01-01

    We present an analytic model for how momentum deposition from stellar feedback simultaneously regulates star formation and drives outflows in a turbulent interstellar medium (ISM). Because the ISM is turbulent, a given patch of ISM exhibits sub-patches with a range of surface densities. The high-density patches are 'pushed' by feedback, thereby driving turbulence and self-regulating local star formation. Sufficiently low-density patches, however, are accelerated to above the escape velocity before the region can self-adjust and are thus vented as outflows. In the turbulent-pressure-supported regime, when the gas fraction is $\\gtrsim 0.3$, the ratio of the turbulent velocity dispersion to the circular velocity is sufficiently high that at any given time, of order half of the ISM has surface density less than the critical value and thus can be blown out on a dynamical time. The resulting outflows have a mass-loading factor ($\\eta \\equiv M_{\\rm out}/M_{\\star}$) that is inversely proportional to the gas fraction ...

  13. Regulation of Memory Formation by the Transcription Factor XBP1.

    Science.gov (United States)

    Martínez, Gabriela; Vidal, René L; Mardones, Pablo; Serrano, Felipe G; Ardiles, Alvaro O; Wirth, Craig; Valdés, Pamela; Thielen, Peter; Schneider, Bernard L; Kerr, Bredford; Valdés, Jose L; Palacios, Adrian G; Inestrosa, Nibaldo C; Glimcher, Laurie H; Hetz, Claudio

    2016-02-16

    Contextual memory formation relies on the induction of new genes in the hippocampus. A polymorphism in the promoter of the transcription factor XBP1 was identified as a risk factor for Alzheimer's disease and bipolar disorders. XBP1 is a major regulator of the unfolded protein response (UPR), mediating adaptation to endoplasmic reticulum (ER) stress. Using a phenotypic screen, we uncovered an unexpected function of XBP1 in cognition and behavior. Mice lacking XBP1 in the nervous system showed specific impairment of contextual memory formation and long-term potentiation (LTP), whereas neuronal XBP1s overexpression improved performance in memory tasks. Gene expression analysis revealed that XBP1 regulates a group of memory-related genes, highlighting brain-derived neurotrophic factor (BDNF), a key component in memory consolidation. Overexpression of BDNF in the hippocampus reversed the XBP1-deficient phenotype. Our study revealed an unanticipated function of XBP1 in cognitive processes that is apparently unrelated to its role in ER stress.

  14. Regulation of Memory Formation by the Transcription Factor XBP1

    Directory of Open Access Journals (Sweden)

    Gabriela Martínez

    2016-02-01

    Full Text Available Contextual memory formation relies on the induction of new genes in the hippocampus. A polymorphism in the promoter of the transcription factor XBP1 was identified as a risk factor for Alzheimer’s disease and bipolar disorders. XBP1 is a major regulator of the unfolded protein response (UPR, mediating adaptation to endoplasmic reticulum (ER stress. Using a phenotypic screen, we uncovered an unexpected function of XBP1 in cognition and behavior. Mice lacking XBP1 in the nervous system showed specific impairment of contextual memory formation and long-term potentiation (LTP, whereas neuronal XBP1s overexpression improved performance in memory tasks. Gene expression analysis revealed that XBP1 regulates a group of memory-related genes, highlighting brain-derived neurotrophic factor (BDNF, a key component in memory consolidation. Overexpression of BDNF in the hippocampus reversed the XBP1-deficient phenotype. Our study revealed an unanticipated function of XBP1 in cognitive processes that is apparently unrelated to its role in ER stress.

  15. Engineering transcriptional regulation to control Pdu microcompartment formation.

    Directory of Open Access Journals (Sweden)

    Edward Y Kim

    Full Text Available Bacterial microcompartments (MCPs show great promise for the organization of engineered metabolic pathways within the bacterial cytoplasm. This subcellular organelle is composed of a protein shell of 100-200 nm diameter that natively encapsulates multi-enzyme pathways. The high energy cost of synthesizing the thousands of protein subunits required for each MCP demands precise regulation of MCP formation for both native and engineered systems. Here, we study the regulation of the propanediol utilization (Pdu MCP, for which growth on 1,2-propanediol induces expression of the Pdu operon for the catabolism of 1,2-propanediol. We construct a fluorescence-based transcriptional reporter to investigate the activation of the Ppdu promoter, which drives the transcription of 21 pdu genes. Guided by this reporter, we find that MCPs can be expressed in strains grown in rich media, provided that glucose is not present. We also characterize the response of the Ppdu promoter to a transcriptional activator of the pdu operon, PocR, and find PocR to be a necessary component of Pdu MCP formation. Furthermore, we find that MCPs form normally upon the heterologous expression of PocR even in the absence of the natural inducer 1,2-propanediol and in the presence of glucose, and that Pdu MCPs formed in response to heterologous PocR expression can metabolize 1,2-propanediol in vivo. We anticipate that this technique of overexpressing a key transcription factor may be used to study and engineer the formation, size, and/or number of MCPs for the Pdu and related MCP systems.

  16. Cyclic expression of lhx2 regulates hair formation.

    Directory of Open Access Journals (Sweden)

    Gunilla Törnqvist

    2010-04-01

    Full Text Available Hair is important for thermoregulation, physical protection, sensory activity, seasonal camouflage, and social interactions. Hair is generated in hair follicles (HFs and, following morphogenesis, HFs undergo cyclic phases of active growth (anagen, regression (catagen, and inactivity (telogen throughout life. The transcriptional regulation of this process is not well understood. We show that the transcription factor Lhx2 is expressed in cells of the outer root sheath and a subpopulation of matrix cells during both morphogenesis and anagen. As the HFs enter telogen, expression becomes undetectable and reappears prior to initiation of anagen in the secondary hair germ. In contrast to previously published results, we find that Lhx2 is primarily expressed by precursor cells outside of the bulge region where the HF stem cells are located. This developmental, stage- and cell-specific expression suggests that Lhx2 regulates the generation and regeneration of hair. In support of this hypothesis, we show that Lhx2 is required for anagen progression and HF morphogenesis. Moreover, transgenic expression of Lhx2 in postnatal HFs is sufficient to induce anagen. Thus, our results reveal an alternative interpretation of Lhx2 function in HFs compared to previously published results, since Lhx2 is periodically expressed, primarily in precursor cells distinct from those in the bulge region, and is an essential positive regulator of hair formation.

  17. An instability of feedback regulated star formation in galactic nuclei

    CERN Document Server

    Torrey, Paul; Faucher-Giguère, Claude-André; Vogelsberger, Mark; Quataert, Eliot; Kereš, Dušan; Murray, Norman

    2016-01-01

    We examine the stability of feedback-regulated star formation (SF) in galactic nuclei and contrast it to SF in extended discs. In galactic nuclei the dynamical time becomes shorter than the time over which feedback from young stars evolves. We argue analytically that the balance between stellar feedback and gravity is unstable in this regime. We study this using numerical simulations with pc-scale resolution and explicit stellar feedback taken from stellar evolution models. The nuclear gas mass, young stellar mass, and SFR within the central ~100 pc (the short-timescale regime) never reach steady-state, but instead go through dramatic, oscillatory cycles. Stars form until a critical surface density of young stars is present (such that feedback overwhelms gravity), at which point they begin to expel gas from the nucleus. Since the dynamical times are shorter than the stellar evolution times, the stars do not die as the gas is expelled, but continue to push, triggering a runaway quenching of star formation in t...

  18. Self-Gravitating Relativistic Fluids: The Formation of a Free Phase Boundary in the Phase Transition from Hard to Soft

    Science.gov (United States)

    Christodoulou, Demetrios; Lisibach, André

    2016-06-01

    In the 1990s Christodoulou introduced an idealized fluid model intended to capture some of the features of the gravitational collapse of a massive star to form a neutron star or a black hole. This was the two-phase model introduced in `Self-gravitating relativistic fluids: a two phase model' (Demeterios, Arch Ration Mech Anal 130:343-400, 1995). The present work deals with the formation of a free phase boundary in the phase transition from hard to soft in this model. In this case the phase boundary has corners at the null points; the points which separate the timelike and spacelike components of the interface between the two phases. We prove the existence and uniqueness of a free phase boundary. Also the local form of the shock near the null point is established.

  19. Formation of the thermal-driven boundary jet in an f-plane mesoscale basin

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The paper adopts an f-plane quasi-geostrophic inertial model without linearization to investigate the perturbation temperature, boundary jet and upwelling (downwelling) in an idealized rectangular basin, under the consideration of west side friction layer and heat conservation. There is net heat input on the upper surface and equal quality heat dissipation on the west boundary, and without heat exchange on other boundaries, then the heat is conservation in the whole basin. Results show that there is thermal front due to denseness of the perturbation temperature in the west side boundary, the perturbation pressure and flow field are reversal on the upper layer and bottom layer. On the bottom layer, the west coastal current is northward, and the maximum perturbation pressure center is on the west, however, on the upper layer, the east coastal current is southward, and the maximum perturbation pressure center is on the east. There is strong vertical flow in narrow western boundary layer, and also in the central zone. The effect of different upper thermal forcings is also studied, and it can be concluded that there is always temperature denseness and boundary jet near the west boundary, and the appearance of flow field reversal, but the distribution of vertical flow is rather different.

  20. vox homeobox gene: a novel regulator of midbrain-hindbrain boundary development in medaka fish?

    Science.gov (United States)

    Fabian, Peter; Pantzartzi, Chrysoula N; Kozmikova, Iryna; Kozmik, Zbynek

    2016-03-01

    The midbrain-hindbrain boundary (MHB) is one of the key organizing centers of the vertebrate central nervous system (CNS). Its patterning is governed by a well-described gene regulatory network (GRN) involving several transcription factors, namely, pax, gbx, en, and otx, together with signaling molecules of the Wnt and Fgf families. Here, we describe the onset of these markers in Oryzias latipes (medaka) early brain development in comparison to previously known zebrafish expression patterns. Moreover, we show for the first time that vox, a member of the vent gene family, is expressed in the developing neural tube similarly to CNS markers. Overexpression of vox leads to profound changes in the gene expression patterns of individual components of MHB-specific GRN, most notably of fgf8, a crucial organizer molecule of MHB. Our data suggest that genes from the vent family, in addition to their crucial role in body axis formation, may play a role in regionalization of vertebrate CNS. PMID:26965282

  1. Fractal pattern formation in thermal grooving at grain boundaries in Ag films on Si(111) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Roy, A. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Sundaravel, B. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Batabyal, R. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Dev, B.N., E-mail: msbnd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2012-05-31

    Growth of Ag films on Br- and H-passivated Si(111) surfaces and the annealing behaviour have been investigated by Rutherford backscattering spectrometry, scanning electron microscopy and photoemission electron microscopy techniques. Upon annealing the phenomenon of thermal grooving was observed in the Ag films. Depending on the annealing temperature, at an intermediate annealing time Ag depletion (evaporation) from the grain boundaries produces fractal patterns of Ag-depleted regions. Continued annealing eventually produces a percolated network of Ag-depleted regions (thermal grooves) along the grain boundaries and isolated Ag grains appear as the depth of the grooves reaches the substrate. For the fractal structures produced by thermal grooving, the fractal dimension has been estimated to be 1.60 {+-} 0.04. Observation of a fractal pattern in thermal grooving was not hitherto reported. A thorough analysis of the experimental results has been carried out in the context of current theories. These theories are inadequate to describe the experimental results. - Highlights: Black-Right-Pointing-Pointer Thermal grooving in Ag films grown on Si(111) surfaces has been investigated. Black-Right-Pointing-Pointer At appropriate temperatures short annealing shows partly depleted grain boundaries. Black-Right-Pointing-Pointer Depleted grain boundaries reveal a fractal pattern with a fractal dimension of 1.60. Black-Right-Pointing-Pointer Long annealing produces percolated Ag-depleted regions with isolated Ag grains. Black-Right-Pointing-Pointer A thorough analysis shows that current theories are unable to explain the results.

  2. Analysis of axon tract formation in the zebrafish brain: the role of territories of gene expression and their boundaries.

    Science.gov (United States)

    Wilson, S W; Brennan, C; Macdonald, R; Brand, M; Holder, N

    1997-11-01

    Mutant analysis in the zebrafish is revealing the genes that are expressed in the early neuroepithelium and that regulate factors responsible for the guidance of commissural axons. We review work on the developing zebrafish brain illustrating the way in which territories of regulatory gene expression influence the formation and positioning of axon pathways. PMID:9321679

  3. Estimation of the ozone formation rate in the atmospheric boundary layer over a background region of Western Siberia

    Science.gov (United States)

    Antokhin, P. N.; Antokhina, O. Y.; Belan, B. D.

    2015-11-01

    The ozone formation rate in the atmospheric boundary layer (ABL) and the ozone inflow from the free atmosphere have been studied experimentally. The obtained estimates are based on the data of airborne sounding carried out over a background region of Western Siberia. As a result, it is obtained that the rate of ozone inflow from the upper atmospheric layers is only 20% of the rate of photochemical formation of ozone inside ABL. The vertical profiles of ozone flows in ABL have been additionally calculated based on the k-theory with the approach proposed by Troen and Mahrt. It has been shown in the calculations that the maximum of the ozone concentration in ABL is formed due to photochemical reactions from precursor gases.

  4. 20 CFR 633.103 - Format for these regulations.

    Science.gov (United States)

    2010-04-01

    ... set forth in 20 CFR part 633 and part 636. These parts contain all the regulations under the Act applicable to migrant and other seasonally employed farmworker programs. (b) Should the regulations at this... 633.103 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR MIGRANT...

  5. Evolution of Prolate Molecular Clouds at Hii Boundaries: II. Formation of BRCs of asymmetrical morphology

    CERN Document Server

    Kinnear, T M; White, G J; Sugitani, K; Goodwin, S

    2015-01-01

    A systematic investigation on the evolution of a prolate cloud at an Hii boundary is conducted using Smoothed Particle Hydrodynamics (SPH) in order to understand the mechanism for a variety of irregular morphological structures found at the boundaries of various Hii regions. The prolate molecular clouds in this investigation are set with their semi-major axes at inclinations between 0 and 90 degrees to a plane parallel ionizing radiation flux. A set of 4 parameters, the number density n, the ratio of major to minor axis gamma, the inclination angle phi and the incident flux F_EUV, are used to define the initial state of the simulated clouds. The dependence of the evolution of a prolate cloud under Radiation Driven Implosion (RDI) on each of the four parameters is investigated. It is found that: i) in addition to the well studied standard type A, B or C Bright Rimmed Clouds (BRCs), many other types such as asymmetrical BRCs, filamentary structures and irregular horse-head structures could also be developed at ...

  6. Integrated biostratigraphy and stage boundaries of the Abderaz Formation, east of the Kopeh-Dagh sedimentary basin, NE Iran

    Science.gov (United States)

    Vahidinia, Mohammad; Youssef, Mohamed; Shafiee Ardestani, Meysam; Sadeghi, Abbas; Dochev, Docho

    2014-02-01

    The foraminiferal content of the well-known, foraminifera-rich Abderaz Formation of the Kopeh-Dagh basin in northeastern Iran was analyzed to determine biostratigraphy, age dating, chronostratigraphy and evolutionary trends. The Abderaz Formation was sampled at the following four sections: the Qarehso section, the Abderaz village section, the Muzduran section and the Shorab section. The Qarehso section is approximately 540 m thick and consists of 77 planktonic foraminifera species belonging to 18 genera in 5 biozones, 10 echinoid species belonging to 4 genera and 8 inoceramid species belonging to 5 genera. Based on this fossil content, the Qarehso section was dated to the lowermost Turonian to the upper Santonian. Based on the first occurrence datums of Cremnoceramus walterdorfensis walterdorfensis and Cremnoceramus deformis deformis and on the FODs of Micraster cortestudinarium and Dicarinella concavata, the Turonian-Conician boundary was detected in this section. In addition, based on the FODs of Echinocorys gr. scutata forma vulgaris, Echinocorys gr. scutata forma vulgaris-planodama and Di. Asymetrica, the base of the Santonian stage was also detected in the Qarehso section. The Abderaz village section is 556.5 m thick and contains 17 genera and 68 species of planktonic foraminifera that have been identified in 9 biozones and 7 genera and 15 species of invertebrates. The lowermost Turonian to the lowermost Campanian ages have been established in the Abderaz Formation. In the Abderaz village section, 3 boundaries were identified. Based on the FODs of Cremnoceramus walterdorfensis walterdorfensis, C. deformis deformis and C. crassus crassus and on the FODs of Contusotruncana fornicata and C. pateliformis, the base of the Coniacian stage was identified. Based on the FODs of Di. asymetrica and Macroglobigerinelloides alvarezi, the Coniacian-Santonian boundary was identified. Additionally, based on the extinction of the Marginotruncanid group and on the LOD of

  7. Additional Boundary Condition for List-Method Directed Forgetting: The Effect of Presentation Format

    Science.gov (United States)

    Hupbach, Almut; Sahakyan, Lili

    2014-01-01

    The attempt to forget some recently encoded information renders this information difficult to recall in a subsequent memory test. "Forget" instructions are only effective when followed by learning of new material. In the present study, we asked whether the new material needs to match the format of the to-be-forgotten information for…

  8. The impact of boundary conditions on CO2 capacity estimation in aquifers

    OpenAIRE

    Smith, D.J.; Bentham, M.; Holloway, S.; Noy, D.J.; Chadwick, R.A.

    2010-01-01

    The boundary conditions of an aquifer determine the extent to which fluids (including formation water and CO2) and pressure can be transferred into adjacent geological formations, either laterally or vertically. Aquifer boundaries can be faults, lithological boundaries, formation pinch-outs, salt walls, or outcrop. In many cases compliance with regulations preventing CO2 storage influencing areas outside artificial boundaries defined by non-geological criteria (international bound...

  9. Marine boundary layer cloud regimes and POC formation in an LES coupled to a bulk aerosol scheme

    Directory of Open Access Journals (Sweden)

    A. H. Berner

    2013-07-01

    Full Text Available A large-eddy simulation (LES coupled to a new bulk aerosol scheme is used to study long-lived regimes of aerosol-boundary layer cloud-precipitation interaction and the development of pockets of open cells (POCs in subtropical stratocumulus cloud layers. The aerosol scheme prognoses mass and number concentration of a single log-normal accumulation mode with surface and entrainment sources, evolving subject to processing of activated aerosol and scavenging of dry aerosol by cloud and rain. The LES with the aerosol scheme is applied to a range of steadily-forced simulations idealized from a well-observed POC case. The long-term system evolution is explored with extended two-dimensional simulations of up to 20 days, mostly with diurnally-averaged insolation. One three-dimensional two-day simulation confirms the initial development of the corresponding two-dimensional case. With weak mean subsidence, an initially aerosol-rich mixed layer deepens, the capping stratocumulus cloud slowly thickens and increasingly depletes aerosol via precipitation accretion, then the boundary layer transitions within a few hours into an open-cell regime with scattered precipitating cumuli, in which entrainment is much weaker. The inversion slowly collapses for several days until the cumulus clouds are too shallow to efficiently precipitate. Inversion cloud then reforms and radiatively drives renewed entrainment, allowing the boundary layer to deepen and become more aerosol-rich, until the stratocumulus layer thickens enough to undergo another cycle of open-cell formation. If mean subsidence is stronger, the stratocumulus never thickens enough to initiate drizzle and settles into a steady state. With lower initial aerosol concentrations, this system quickly transitions into open cells, collapses, and redevelops into a different steady state with a shallow, optically thin cloud layer. In these steady states, interstitial scavenging by cloud droplets is the main sink of

  10. Cooperative action of the paralogous maize lateral organ boundaries (LOB) domain proteins RTCS and RTCL in shoot-borne root formation.

    Science.gov (United States)

    Xu, Changzheng; Tai, Huanhuan; Saleem, Muhammad; Ludwig, Yvonne; Majer, Christine; Berendzen, Kenneth W; Nagel, Kerstin A; Wojciechowski, Tobias; Meeley, Robert B; Taramino, Graziana; Hochholdinger, Frank

    2015-09-01

    The paralogous maize (Zea mays) LBD (Lateral Organ Boundaries Domain) genes rtcs (rootless concerning crown and seminal roots) and rtcl (rtcs-like) emerged from an ancient whole-genome duplication. RTCS is a key regulator of crown root initiation. The diversity of expression, molecular interaction and phenotype of rtcs and rtcl were investigated. The rtcs and rtcl genes display highly correlated spatio-temporal expression patterns in roots, despite the significantly higher expression of rtcs. Both RTCS and RTCL proteins bind to LBD downstream promoters and act as transcription factors. In line with its auxin inducibility and binding to auxin response elements of rtcs and rtcl promoters, ARF34 (AUXIN RESPONSE FACTOR 34) acts as transcriptional activator. Yeast two-hybrid screening combined with bimolecular fluorescence complementation (BiFC) experiments revealed conserved and unique interaction partners of RTCS and RTCL. The rtcl mutation leads to defective shoot-borne root elongation early in development. Cooperative action of RTCS and RTCL during shoot-borne root formation was demonstrated by rtcs-dependent repression of rtcl transcription in coleoptilar nodes. Although RTCS is instrumental in shoot-borne root initiation, RTCL controls shoot-borne root elongation early in development. Their conserved role in auxin signaling, but diverse function in shoot-borne root formation, is underscored by their conserved and unique interaction partners. PMID:25902765

  11. [Research advances on regulation of Pseudomonas aeruginosa biofilm formation and its therapeutic strategies].

    Science.gov (United States)

    Wang, Wen-min; Xu, Zhi-hao

    2010-01-01

    Pseudomonas aeruginosa is an important pathogenic bacterium of nosocomial infections. The microbe easily produce biofilm which brings us much difficulties in clinical treatment. The formation processes of biofilm, including the stages of early bacteria planting, mushroom-like structure forming and extracellular matrix producing, are regulated by a series of molecules and genes. And quorum sensing system of the microbe is responsible for regulation of the whole process of biofilm formation. According to the process of biofilm formation and the mimitat associated regulation mechanism, several anti-biofilm therapeutic strategies have been applied in clinical medicine, and some novel drugs and methods are developed. PMID:20175245

  12. Feedback Regulated Star Formation: From Star Clusters to Galaxies

    CERN Document Server

    Dib, Sami

    2011-01-01

    This paper summarises results from semi-analytical modelling of star formation in protocluster clumps of different metallicities. In this model, gravitationally bound cores form uniformly in the clump following a prescribed core formation efficiency per unit time. After a contraction timescale which is equal to a few times their free-fall times, the cores collapse into stars and populate the IMF. Feedback from the newly formed OB stars is taken into account in the form of stellar winds. When the ratio of the effective wind energy of the winds to the gravitational energy of the system reaches unity, gas is removed from the clump and core and star formation are quenched. The power of the radiation driven winds has a strong dependence on metallicity and increases with increasing metallicity. Thus, winds from stars in the high metallicity models lead to a rapid evacuation of the gas from the protocluster clump and to a reduced star formation efficiency, SFE_{exp}, as compared to their low metallicity counterparts...

  13. Pattern formation in a gene network model with boundary shape dependence

    Science.gov (United States)

    Diambra, Luis; da Fontoura Costa, Luciano

    2006-03-01

    A fundamental task in developmental biology is to identify the mechanisms which drive morphogenesis. Traditionally pattern formation have been modeled mainly using Turing-type mechanisms, where complex patterns arise by symmetry breaking. However, there is a growing experimental evidence that the influence of signals derived from surrounding tissues can contribute to the patterning processes. In this paper, we show that the interplay between the shape of surrounding tissues and a hierarchically organized gene regulatory network can be able to induce stable complex patterns. The rise of these patterns depends strongly on the shape of the surrounding tissues.

  14. HDAC2 Negatively Regulates Memory Formation and Synaptic Plasticity

    OpenAIRE

    Guan, Ji-Song; Giacometti, Emanuela; Dannenberg, Jan-Hermen; Joseph, Nadine; Gao, Jun; DePinho, Ronald A.; Jaenisch, Rudolf; Tsai, Li-Huei; Haggarty, Stephen John; Nieland, Thomas; Ying ZHOU; Wang, Xinyu; Mazitschek, Ralph; Bradner, James Elliott

    2012-01-01

    Chromatin modifications, especially histone-tail acetylation, have been implicated in memory formation. Increased histone-tail acetylation induced by inhibitors of histone deacetylases (HDACis) facilitates learning and memory in wild-type mice as well as in mouse models of neurodegeneration. Harnessing the therapeutic potential of HDACis requires knowledge of the specific HDAC family member(s) linked to cognitive enhancement. Here we show that neuron-specific overexpression of HDAC2, but not ...

  15. High-gain adaptive regulator for a string equation with uncertain harmonic disturbance under boundary output feedback control

    Institute of Scientific and Technical Information of China (English)

    Baozhu GUO; Wei GUO

    2003-01-01

    This paper considers the boundary stabilization and parameter estimation of a one-dimensional wave equation in the case when one end is fixed and control and harmonic disturbance with uncertain amplitude are input at another end. A high-gain adaptive regulator is designed in terms of measured collocated end velocity. The existence and uniqueness of the classical solution of the closed-loop system is proven. It is shown that the state of the system approaches the standstill as time goes to infitv and meanwhile, the estimated parameter converges to the unknown parameter.

  16. Structural constraints regulating triple helix formation by A-tracts.

    Science.gov (United States)

    Sen, A; Gräslund, A

    2000-12-15

    The study concerns the propensity of triple helix formation by different DNA oligonucleotides containing long A-tracts with and without flanking GxC base pairs in order to probe the role of length of the A-tract and the flanking sequences. From nuclear magnetic resonance (NMR) studies of imino proton spectra and circular dichroism (CD) spectroscopy of samples composed of potential triplex forming strand sequences in correct stoichiometries, we have concluded that 8-mer A-tracts flanked by GxC base pairs exert significant steric hindrance to triple helix formation. When as much as 50 mM Mg2+ was added, no triple helix formation was observed in these samples. In contrast, open-ended 8-mer A-tracts formed triplex with the corresponding two T8 strands under relatively mild ionic conditions (100 mM Na+). Moreover, the shorter the length of the A-tract, the less is the hindrance to form a triple helix. PMID:11152277

  17. Environmental regulation of cloud and star formation in galactic bars

    CERN Document Server

    Renaud, F; Emsellem, E; Agertz, O; Athanassoula, E; Combes, F; Elmegreen, B; Kraljic, K; Motte, F; Teyssier, R

    2015-01-01

    The strong time-dependence of the dynamics of galactic bars yields a complex and rapidly evolving distribution of dense gas and star forming regions. Although bars mainly host regions void of any star formation activity, their extremities can gather the physical conditions for the formation of molecular complexes and mini-starbursts. Using a sub-parsec resolution hydrodynamical simulation of a Milky Way-like galaxy, we probe these conditions to explore how and where bar (hydro-)dynamics favours the formation or destruction of molecular clouds and stars. The interplay between the kpc-scale dynamics (gas flows, shear) and the parsec-scale (turbulence) is key to this problem. We find a strong dichotomy between the leading and trailing sides of the bar, in term of cloud fragmentation and in the age distribution of the young stars. After orbiting along the bar edge, these young structures slow down at the extremities of the bar, where orbital crowding increases the probability of cloud-cloud collision. We find tha...

  18. Experimental study of boundary layers formation by thin film colorimetric interferometry

    Institute of Scientific and Technical Information of China (English)

    MartinHartl; IvanKrupka; MiroslavLiska

    2001-01-01

    Thin film colorimetric interferometry was applied to the preliminary study of boundarylayers formation for a several liquids of known molecular structure that have been previously stud-ied by the force balance method. This technique intended for the study of very thin lubrication filmsdown to a few nanometers in a point contact between a steel ball and a transparent disk combinespowerful film thickness mapping capabilities with high accuracy. Central and minimum film thick-ness as well as film shape in the dependence on rolling speed was studied for hexadecane, oc-tamethylcyclotetrasiloxane (OMCTS) and n-tetradecane. Results are compared with data obtainedfrom surface force apparatus measurements. OMCTS and n-tetradecane were found to formboundary films that result in a considerable enhancement in film thickness at slow speeds.

  19. From dynamic expression patterns to boundary formation in the presomitic mesoderm.

    Directory of Open Access Journals (Sweden)

    Hendrik B Tiedemann

    Full Text Available The segmentation of the vertebrate body is laid down during early embryogenesis. The formation of signaling gradients, the periodic expression of genes of the Notch-, Fgf- and Wnt-pathways and their interplay in the unsegmented presomitic mesoderm (PSM precedes the rhythmic budding of nascent somites at its anterior end, which later develops into epithelialized structures, the somites. Although many in silico models describing partial aspects of somitogenesis already exist, simulations of a complete causal chain from gene expression in the growth zone via the interaction of multiple cells to segmentation are rare. Here, we present an enhanced gene regulatory network (GRN for mice in a simulation program that models the growing PSM by many virtual cells and integrates WNT3A and FGF8 gradient formation, periodic gene expression and Delta/Notch signaling. Assuming Hes7 as core of the somitogenesis clock and LFNG as modulator, we postulate a negative feedback of HES7 on Dll1 leading to an oscillating Dll1 expression as seen in vivo. Furthermore, we are able to simulate the experimentally observed wave of activated NOTCH (NICD as a result of the interactions in the GRN. We esteem our model as robust for a wide range of parameter values with the Hes7 mRNA and protein decays exerting a strong influence on the core oscillator. Moreover, our model predicts interference between Hes1 and HES7 oscillators when their intrinsic frequencies differ. In conclusion, we have built a comprehensive model of somitogenesis with HES7 as core oscillator that is able to reproduce many experimentally observed data in mice.

  20. Interchange Reconnection and Slow Solar Wind Formation at the boundaries of open field regions in the Solar Corona

    Science.gov (United States)

    Rappazzo, A. F.; Matthaeus, W. H.; Ruffolo, D. J.; Servidio, S.; Velli, M.

    2014-12-01

    Interchange reconnection, i.e., magnetic reconnection at the interface between open and closed corona, is thought to contribute to the formation of the slowsolar wind, since it can inject the hotter and denserplasma from closed regions into the heliosphere,and account for the different slow wind composition (thatis similar to the plasma of closed regions) respectto the fast wind. The interchange process has mostly been investigatedfor magnetic field lines with opposite polarity and null points, either for the case of counterdirected loops (e.g., Fisk et al. 1999, Fisk and Schwadron 2001), or in correspondence of null points at the apex of streamers or pseudo-streamers (e.g., Wang et al. 1998,Edmondson et al. 2010, Del Zanna et al. 2011).Magnetic reconnection can certainly occur in these configurations,but they occupy a very small volume of the corona. On the other hand component magnetic reconnection at the boundarybetween coronal holes and streamers or pseudo-streamers hasreceived less attention, even though it can occur aroundthe entire extension of such boundaries. Magnetic reconnection is at the basis of Parker'snanoflare scenario for the heating of coronal loops.Modeling such regions in cartesian geometry with a strongguide field, it has been shown numerically that photosphericmotions induce a magnetic fieldcomponent orthogonal to the strong axial field characterizedby the presence of many current sheets, where the field lines are locally oppositely directed, and can reconnect (Einaudi et al. 1996; Dmitruk and Gomez 1997).The reconnection of the orthogonal component of the magneticfield leads to a change of connectivity of the field linesof the total magnetic field that connect one photospheric boundaryto the other. We have shown that a similar interchange mechanismcan operate in and around the boundaries between open and closedregions inducing a continual stochastic rearrangement of connectivityeverywhere along the open-closed boundary (Rappazzo et al. 2012

  1. Western boundary currents regulated by interaction between ocean eddies and the atmosphere

    Science.gov (United States)

    Ma, Xiaohui; Jing, Zhao; Chang, Ping; Liu, Xue; Montuoro, Raffaele; Small, R. Justin; Bryan, Frank O.; Greatbatch, Richard J.; Brandt, Peter; Wu, Dexing; Lin, Xiaopei; Wu, Lixin

    2016-07-01

    Current climate models systematically underestimate the strength of oceanic fronts associated with strong western boundary currents, such as the Kuroshio and Gulf Stream Extensions, and have difficulty simulating their positions at the mid-latitude ocean’s western boundaries. Even with an enhanced grid resolution to resolve ocean mesoscale eddies—energetic circulations with horizontal scales of about a hundred kilometres that strongly interact with the fronts and currents—the bias problem can still persist; to improve climate models we need a better understanding of the dynamics governing these oceanic frontal regimes. Yet prevailing theories about the western boundary fronts are based on ocean internal dynamics without taking into consideration the intense air–sea feedbacks in these oceanic frontal regions. Here, by focusing on the Kuroshio Extension Jet east of Japan as the direct continuation of the Kuroshio, we show that feedback between ocean mesoscale eddies and the atmosphere (OME-A) is fundamental to the dynamics and control of these energetic currents. Suppressing OME-A feedback in eddy-resolving coupled climate model simulations results in a 20–40 per cent weakening in the Kuroshio Extension Jet. This is because OME-A feedback dominates eddy potential energy destruction, which dissipates more than 70 per cent of the eddy potential energy extracted from the Kuroshio Extension Jet. The absence of OME-A feedback inevitably leads to a reduction in eddy potential energy production in order to balance the energy budget, which results in a weakened mean current. The finding has important implications for improving climate models’ representation of major oceanic fronts, which are essential components in the simulation and prediction of extratropical storms and other extreme events, as well as in the projection of the effect on these events of climate change.

  2. Feedback-regulated Super Massive Black Hole Seed Formation

    CERN Document Server

    Dijkstra, Mark; Mesinger, Andrei

    2014-01-01

    The nature of the seeds of high-redshift supermassive black holes (SMBHs) is a key question in cosmology. Direct collapse black holes (DCBH) that form in pristine, atomic-line cooling halos, illuminated by a Lyman-Werner (LW) UV flux exceeding a critical threshold J_crit, represent an attractive possibility. We investigate when and where these conditions are met during cosmic evolution. For the LW intensity, J_LW, we account for departures from the background value in close proximity to star forming galaxies. For the pristine halo fraction, we account for both (i) supernova driven outflows, and (ii) the inherent pollution from progenitor halos. We estimate the abundance of DCBH formation sites, n_DCBH(z), and find that it increases with cosmic time from n_DCBH(z=20) ~ 1e-12 -1e-7 cMpc^-3 to n_DCBH(z=10) ~ 1e-10 - 1e-5 cMpc^-3. Our analysis shows the possible importance of galactic winds, which can suppress the predicted n_DCBH by several orders of magnitude, and cause DCBH formation to preferentially occur ar...

  3. Feedback-regulated supermassive black hole seed formation

    Science.gov (United States)

    Dijkstra, Mark; Ferrara, Andrea; Mesinger, Andrei

    2014-08-01

    The nature of the seeds of high-redshift supermassive black holes (SMBHs) is a key question in cosmology. Direct collapse black holes (DCBHs) that form in pristine, atomic-line cooling haloes, illuminated by a Lyman-Werner (LW) UV flux exceeding a critical threshold Jcrit represent an attractive possibility. We investigate when and where these conditions are met during cosmic evolution. For the LW intensity, JLW, we account for departures from the background value in close proximity to star-forming galaxies. For the pristine halo fraction, we account for both (i) supernova-driven outflows and (ii) the inherent pollution from progenitor haloes. We estimate the abundance of DCBH formation sites, nDCBH(z), and find that it increases with cosmic time from nDCBH(z = 20) ˜ 10-12-10-7 cMpc-3 to nDCBH(z = 10) ˜ 10-10-10-5 cMpc-3. Our analysis shows the possible importance of galactic winds, which can suppress the predicted nDCBH by several orders of magnitude, and cause DCBH formation to preferentially occur around the UV-brightest (MUV ˜ -21 ± 1) star-forming galaxies. Our analysis further highlights the dependence of these predictions on (i) the escape fraction of LW photons, (ii) Jcrit, and (iii) the galactic outflow prescription.

  4. Environment and self-regulation in galaxy formation

    CERN Document Server

    Thomas, Daniel; Schawinski, Kevin; Sarzi, Marc; Silk, Joseph

    2009-01-01

    The environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology-density relationship. In this paper we study the effect of environment on the evolution of early-type galaxies by analysing the stellar population properties of 3,360 galaxies morphologically selected by visual inspection from the SDSS in the redshift range 0.05formation through their emissio...

  5. Cholesterol Regulates Syntaxin 6 Trafficking at trans-Golgi Network Endosomal Boundaries

    Directory of Open Access Journals (Sweden)

    Meritxell Reverter

    2014-05-01

    Full Text Available Inhibition of cholesterol export from late endosomes causes cellular cholesterol imbalance, including cholesterol depletion in the trans-Golgi network (TGN. Here, using Chinese hamster ovary (CHO Niemann-Pick type C1 (NPC1 mutant cell lines and human NPC1 mutant fibroblasts, we show that altered cholesterol levels at the TGN/endosome boundaries trigger Syntaxin 6 (Stx6 accumulation into VAMP3, transferrin, and Rab11-positive recycling endosomes (REs. This increases Stx6/VAMP3 interaction and interferes with the recycling of αVβ3 and α5β1 integrins and cell migration, possibly in a Stx6-dependent manner. In NPC1 mutant cells, restoration of cholesterol levels in the TGN, but not inhibition of VAMP3, restores the steady-state localization of Stx6 in the TGN. Furthermore, elevation of RE cholesterol is associated with increased amounts of Stx6 in RE. Hence, the fine-tuning of cholesterol levels at the TGN-RE boundaries together with a subset of cholesterol-sensitive SNARE proteins may play a regulatory role in cell migration and invasion.

  6. Relationship between Protein Accumulation Regulation and Yield Formation in Soybean

    Institute of Scientific and Technical Information of China (English)

    CHEN Lihua; LI Jie; LIU Lijun; ZU Wei

    2006-01-01

    Three different genotypes soybeans were adopted in this experiment under three fertilizer levels.The object of this study was to investigate protein accumulation regulation of soybean cultivars under the condition of different nutrient levels, and their effects on soybean yield and quality, and to provide theoretical evidence for breed, cultivation and agricultural production, also man-powered controllable locations. The concentration of N in the leaves declined after seedling stage, then increased again at stage of early flowering, and started to decrease up to leaf senescence, declined rapidly from seed-filling season to stage of yellow ripeness. The concentration of N in the stems and pod walls declined with growth stage. High seed protein genotypes exhibited higher N assimilating and partitioning during whole growth stages. Pod walls were media of N partitioning. Protein was accumulated mainly during the later period of reproductive growth stage up to harvest, so plant growth after stage of yellow ripeness could not be neglected.

  7. SarA is a negative regulator of Staphylococcus epidermidis biofilm formation

    DEFF Research Database (Denmark)

    Martin, Christer; Heinze, C.; Busch, M.;

    2012-01-01

    Biofilm formation is essential for Staphylococcus epidermidis pathogenicity in implant-associated infections. Nonetheless, large proportions of invasive S. epidermidis isolates fail to show accumulative biofilm growth in vitro. We here tested the hypothesis that this apparent paradox is related...... to the existence of superimposed regulatory systems suppressing a multi-cellular biofilm life style in vitro. Transposon mutagenesis of clinical significant but biofilm-negative S. epidermidis 1585 was used to isolate a biofilm positive mutant carrying a Tn917 insertion in sarA,chief regulator of staphylococcal...... regulator of Embp- and eDNA dependent biofilm formation. Given the importance of SarA as a positive regulator of polysaccharide mediated cell aggregation, the regulator enables S. epidermidis to switch between mechanisms of biofilm formation, ensuring S. epidermidis adaptation to hostile environments....

  8. Magnetically self-regulated formation of early protoplanetary discs

    CERN Document Server

    Hennebelle, Patrick; Chabrier, Gilles; Marchand, Pierre

    2016-01-01

    The formation of protoplanetary discs during the collapse of molecular dense cores is significantly influenced by angular momentum transport, notably by the magnetic torque. In turn, the evolution of the magnetic field is determined by dynamical processes and non-ideal MHD effects such as ambipolar diffusion. Considering simple relations between various timescales characteristic of the magnetized collapse, we derive an expression for the early disc radius, $ r \\simeq 18 \\, {\\rm AU} \\, \\left({\\eta_{\\rm AD} / 0.1 \\, {\\rm s}} \\right)^{2/9} \\left({B_z / 0.1\\, {\\rm G}} \\right) ^{-4/9} \\left({M / 0.1 \\msol} \\right) ^{1/3},$ where $M$ is the total disc plus protostar mass, $\\eta_\\mathrm{AD}$ is the ambipolar diffusion coefficient and $B_z$ is the magnetic field in the inner part of the core. This is about significantly smaller than the discs that would form if angular momentum was conserved. The analytical predictions are confronted against a large sample of 3D, non-ideal MHD collapse calculations covering variation...

  9. Collaborative jurisdiction in the regulation of electric utilities: A new look at jurisdictional boundaries

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-12-31

    This conference is one of several activities initiated by FERC, DOE and NARUC to improve the dialogue between Federal and State regulators and policymakers. I am pleased to be here to participate in this conference and to address, with you, electricity issues of truly national significance. I would like to commend Ashley Brown and the NARUC Electricity Committee for its foresight in devising a conference on these issues at this critical juncture in the regulation of the electric utility industry. I also would like to commend Chairman Allday and the FERC for their efforts to improve communication between Federal and State electricity regulators; both through FERC`s Public Conference on Electricity Issues that was held last June, and through the FERC/NARUC workshops that are scheduled to follow this conference. These collaborative efforts are important and necessary steps in addressing successfully the many issues facing the electric utility industry those who regulate it, and those who depend upon it - in other words, about everyone.

  10. Magnetically Self-regulated Formation of Early Protoplanetary Disks

    Science.gov (United States)

    Hennebelle, Patrick; Commerçon, Benoît; Chabrier, Gilles; Marchand, Pierre

    2016-10-01

    The formation of protoplanetary disks during the collapse of molecular dense cores is significantly influenced by angular momentum transport, notably by the magnetic torque. In turn, the evolution of the magnetic field is determined by dynamical processes and non-ideal MHD effects such as ambipolar diffusion. Considering simple relations between various timescales characteristic of the magnetized collapse, we derive an expression for the early disk radius, r≃ 18 {au} {({η }{AD}/0.1{{s}})}2/9{({B}z/0.1{{G}})}-4/9{(M/0.1{M}ȯ )}1/3, where M is the total disk plus protostar mass, {η }{AD} is the ambipolar diffusion coefficient, and B z is the magnetic field in the inner part of the core. This is significantly smaller than the disks that would form if angular momentum was conserved. The analytical predictions are confronted against a large sample of 3D, non-ideal MHD collapse calculations covering variations of a factor 100 in core mass, a factor 10 in the level of turbulence, a factor 5 in rotation, and magnetic mass-to-flux over critical mass-to-flux ratios 2 and 5. The disk radius estimates are found to agree with the numerical simulations within less than a factor 2. A striking prediction of our analysis is the weak dependence of circumstellar disk radii upon the various relevant quantities, suggesting weak variations among class-0 disk sizes. In some cases, we note the onset of large spiral arms beyond this radius.

  11. Crystallographic Fabrics, Grain Boundary Microstructure and Shape Preferred Orientation of Deformed Banded Iron Formations and their Significance for Deformation Interpretation

    Science.gov (United States)

    Ávila, Carlos Fernando; Graça, Leonardo; Lagoeiro, Leonardo; Ferreira, Filippe

    2016-04-01

    The characterization of grain boundaries and shapes along with crystallographic preferred orientations (CPOs) are a key aspect of investigations of rock microstructures for their correlation with deformation mechanisms. Rapid developments have occurred in the studying rock microstructures due to recent improvements in analytical techniques such as Electron Backscatter Diffraction (EBSD). EBSD technique allows quick automated microtextural characteritzation. The deformed banded iron formations (BIFs) occurring in the Quadrilátero Ferrífero (QF) province in Brazil have been studied extensively with EBSD. All studies have focused mainly in CPOs. The general agreement is that dislocation creep was the dominant process of deformation, for the strong c-axis fabric of hematite crystals. This idea is substantiated by viscoplastic self-consistent models for deformation of hematite. However there are limitations to analyzing natural CPOs alone, or those generated by deformation models. The strong c-axis fabric could be taken as equally powerful an evidence for other known deformation mechanisms. Some grain boundary types in BIFs of the QF are irregular and comprise equant grains in granoblastic texture (Figure 1a). CPOs for this kind are strong and consistent with a predominance of dislocation creep. Others are very regular and long parallel to basal planes of hematites forming large elongated crystals (lepidoblastic texture, Figure 1b). Such crystals are called specularite, and their formation has been previously attributed to dislocation creep. This is erroneous because of the high strains which would be required. Their shape must be due to anisotropic grain growth. Other types lie between the above end-textures. Both types of grain shape microstructures have the same core deformation mechanism. Describing their genetic differences is crucial, since specularite owe its shape to anisotropic grain growth. It is not possible yet to confirm that dislocation creep was the

  12. Position of the Triassic-Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA

    Science.gov (United States)

    Lucas, S.G.; Tanner, L.H.; Donohoo-Hurley, L.; Geissman, J.W.; Kozur, H.W.; Heckert, A.B.; Weems, R.E.

    2011-01-01

    Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah-Arizona, U.S.A., represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic-Jurassic boundary. We present a synthesis of new biostratigraphic and magnetostratigraphic data collected from across the Moenave Formation outcrop belt, which extends from the St. George area in southwestern Utah to the Tuba City area in northern Arizona. These data include palynomorphs, conchostracans and vertebrate fossils (including footprints) and a composite polarity record based on four overlapping magnetostratigraphic sections. Placement of the Triassic-Jurassic boundary in strata of the Moenave Formation has long been imprecise and debatable, but these new data (especially the conchostracans) allow us to place the Triassic-Jurassic boundary relatively precisely in the middle part of the Whitmore Point Member of the Moenave Formation, stratigraphically well above the highest occurrence of crurotarsan body fossils or footprints. Correlation to marine sections based on this placement indicates that major terrestrial vertebrate extinctions preceded marine extinctions across the Triassic-Jurassic boundary and therefore were likely unrelated to the Central Atlantic Magmatic Province (CAMP) volcanism. ?? 2011 Elsevier B.V.

  13. The effect of M23C6 carbides on the formation of grain boundary serrations in a wrought Ni-based superalloy

    International Nuclear Information System (INIS)

    Highlights: ► The characteristics of GBS are dependent on the solution treatment conditions. ► The morphology of M23C6 carbides have a direct influence on the formation of GBS. ► The difference of diffusivity at interfaces cause M23C6 carbides and serrations. - Abstract: The effect of M23C6 carbides on the formation of grain boundary serrations (GBSs) has been systematically investigated in a solid solution strengthened Haynes 230 alloy. It is found that GBS occur in this alloy during the slow cooling process and are accompanied by the precipitation of intergranular planar M23C6 carbides. The amplitude and proportion of GBS increase with the rise of the solution temperature and time. If the specimens are cooled directly without any solution treatments, the grain boundaries remain planar and granular M23C6 carbides precipitate at them. The sequential evolutions of GBS and M23C6 carbides are investigated by scanning electron microscopy (SEM) examination. High-resolution transmission electron microscope (HRTEM) investigations reveal the coherent interfacial plane of M23C6 carbides formed at grain boundaries to be (111¯). These facts indicate that the nucleation and oriented growth of M23C6 carbides at grain boundaries play an important role in the formation of GBS. Based on the interfacial energy calculations and the tensions balance relation, a semi-quantitative model about the GBS formation is proposed.

  14. Formation of Highly Misoriented Fragments at Hot Band Grain Boundaries During Cold Rolling of Interstitial-Free Steel

    Science.gov (United States)

    Afrin, Nasima; Quadir, Md. Zakaria; Ferry, Michael

    2015-07-01

    The deformation heterogeneities that form in the vicinity of prior hot band grain boundaries in a 75 pct cold-rolled interstitial-free steel have been investigated by 3D electron backscatter diffraction. Grain boundary-affected regions occupy a large fraction of the overall material volume. The coexistence of several features, such as steep orientation gradients up to 5 deg/ μm, high-angle boundary networks, and thin, elongated grain boundary fragments, has confirmed the highly complex nature of these regions. Most notably, these thin boundary fragments were found to be significantly misoriented from any of the deformed grains immediately adjacent to the boundary. Overall, grain boundary regions adopt the so-called `deformation banding' mode of deformations on both the micro ( e.g., steep gradients)- and nano ( e.g., thin fragments)-length scales. Grain boundary structures comprise the essential features to act as preferred sites for recrystallization. The discovery of numerous thin grain boundary fragments in the deformation microstructure provides a plausible explanation for the origin of recrystallized grains with orientations other than those found within the adjoining deformed grains in the vicinity of grain boundaries; this phenomenon has been commonly observed in texture data for many years but remained unexplained.

  15. Transmembrane Agrin Regulates Dendritic Filopodia and Synapse Formation in Mature Hippocampal Neuron Cultures

    OpenAIRE

    McCroskery, Seumas; Bailey, Allison; Lin, Lin; Daniels, Mathew P.

    2009-01-01

    The transmembrane isoform of agrin (Tm-agrin) is the predominant form expressed in the brain but its putative roles in brain development are not well understood. Recent reports have implicated Tm-agrin in the formation and stabilization of filopodia on neurites of immature central and peripheral neurons in culture. In maturing central neurons, dendritic filopodia are believed to facilitate synapse formation. In the present study we have investigated the role of Tm-agrin in regulation of dendr...

  16. GEOTAIL observation of tilted X-line formation during flux transfer events (FTEs in the dayside magnetospheric boundary layers

    Directory of Open Access Journals (Sweden)

    M. Nowada

    2004-09-01

    Full Text Available The magnetic field and plasma structures during two successive crossings of the subsolar magnetospheric boundary layers (i.e. MagnetoPause Current Layer (MPCL and Low-Latitude Boundary Layer (LLBL under the southward-dawnward IMF are examined on the basis of the data obtained by the GEOTAIL spacecraft. A significant and interesting feature is found, that is, Flux Transfer Events (FTEs occur in association with the formation of the tilted X-line. During the first inbound MPCL/LLBL crossing, the ion velocity enhancement (in particular, the Vl component negatively increases can be observed in association with simultaneous typical bipolar signature (positive followed by negative in the Bn component. In addition, a clear D-shaped ion distribution whose origin is the magnetosheath can also be found in the dawnward direction. A few minutes later, the satellite experiences outbound MPCL crossing. The negative enhancement of the Vm component can be found as well as the positive enhancement of the Vl component. Simultaneously, a typical bipolar signature with the polarity (negative followed by positive opposite that observed in the first encounter can also be observed. The ions from the magnetosheath flow predominantly in the duskward direction, although the D-shaped ion distribution cannot be observed. These results indicate that the satellite initially observes one part of a reconnected flux tube formed by FTEs whose magnetospheric side is anchored to the Southern Hemisphere. The ions confined in this partial flux tube are flowing in the south-dawnward direction. Then, the satellite observes the other part of the reconnected flux tube whose magnetospheric side is anchored to the Northern Hemisphere. The ions confined in this flux tube flow dominantly in the north-duskward direction. Furthermore, it can be considered that the second MPCL crossing is a direct cut through the diffusion

  17. Techniques for jar formation of valve-regulated lead-acid batteries

    Science.gov (United States)

    Weighall, M. J.

    The market for valve-regulated lead-acid (VRLA) batteries is growing steadily and will be given a further boost as the market for 36-V batteries for the 42-V PowerNet develops over the next few years. The manufacture of VRLA batteries poses, however, a number of complex technical problems that are not experienced in the manufacture of conventional flooded batteries. For the large-scale manufacture of automotive batteries or other small VRLA batteries of 100 Ah or less, jar formation rather than plate formation and dry charge would seem to be a logical and economically sound decision. For this to be successful, however, a number of key issues need to be reviewed, starting with a detailed consideration of battery design. This paper reviews issues associated with the jar formation of VRLA batteries. Guidance is given concerning filling techniques (gravity or vacuum fill), the formation process, charging techniques, and formation algorithms. Battery design and separator optimisation is discussed. The properties of the separator, e.g. wicking rate, fibre composition, surface area and compression, may have a critical impact on acid filling and jar formation, and may partially determine the filling and formation conditions to be used. The control of temperature during formation is particularly important. Formation algorithms and temperature data are presented. Attention is drawn to the possible loss of plate-group compression during the formation process, and how this may be avoided.

  18. HOXC9 regulates formation of parachordal lymphangioplasts and the thoracic duct in zebrafish via stabilin 2.

    Directory of Open Access Journals (Sweden)

    Sandra J Stoll

    Full Text Available HOXC9 belongs to the family of homeobox transcription factors, which are regulators of body patterning and development. HOXC9 acts as a negative regulator on blood endothelial cells but its function on lymphatic vessel development has not been studied. The hyaluronan receptor homologs stabilin 1 and stabilin 2 are expressed in endothelial cells but their role in vascular development is poorly understood. This study was aimed at investigating the function of HOXC9, stabilin 2 and stabilin 1 in lymphatic vessel development in zebrafish and in endothelial cells. Morpholino-based expression silencing of HOXC9 repressed parachordal lymphangioblast assembly and thoracic duct formation in zebrafish. HOXC9 positively regulated stabilin 2 expression in zebrafish and in HUVECs and expression silencing of stabilin 2 phenocopied the HOXC9 morphant vascular phenotype. This effect could be compensated by HOXC9 mRNA injection in stabilin 2 morphant zebrafish embryos. Stabilin 1 also regulated parachordal lymphangioblast and thoracic duct formation in zebrafish but acts independently of HOXC9. On a cellular level stabilin 1 and stabilin 2 regulated endothelial cell migration and in-gel sprouting angiogenesis in endothelial cells. HOXC9 was identified as novel transcriptional regulator of parachordal lymphangioblast assembly and thoracic duct formation in zebrafish that acts via stabilin 2. Stabilin 1, which acts independently of HOXC9, has a similar function in zebrafish and both receptors control important cellular processes in endothelial cells.

  19. Constraints on the upper boundary age of the Tiaojishan Formation volcanic rocks in West Liaoning-North Hebei by LA-ICP-MS dating

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong; WANG MingXin; LIU XiaoMing

    2008-01-01

    In West Liaoning-North Hebei, the Tiaojishan Formation volcanic rocks are developed and many iso-topic ages with a very wide age range were obtained in them as well. These different ages have direct influence on confirming and interpreting the related geological issues in West Liaoning-North Hebei and have restricted the study of geological problems related. In the field, the Tiaojishan Formation and the overlying Tuchengzi Formation are in parallel unconformable contact. By systematical sampling and dating of LA-ICP-MS in the Tiaojishan Formation (especially in the upper part) in Luanping, Chengde basins of Northern Hebei Province and in Lingyuan, Jinlingsi-Yangshan basins of Western Liaoning Province, combined with the dating data obtained by previous researchers, results indicatethat the upper boundary age of the Tiaojishan Formation is from 156 to 153 Ma, and the lower boundary age of the Tiaojishan Formation is about 165 Ma, the Tiaojishan Formation was formed from the late of middle Jurassic to late Jurassic Epoch.

  20. Regulation of type 1 fimbriae synthesis and biofilm formation by the transcriptional regulator LrhA of Escherichia coli.

    Science.gov (United States)

    Blumer, Caroline; Kleefeld, Alexandra; Lehnen, Daniela; Heintz, Margit; Dobrindt, Ulrich; Nagy, Gábor; Michaelis, Kai; Emödy, Levente; Polen, Tino; Rachel, Reinhard; Wendisch, Volker F; Unden, Gottfried

    2005-10-01

    Type 1 fimbriae of Escherichia coli facilitate attachment to the host mucosa and promote biofilm formation on abiotic surfaces. The transcriptional regulator LrhA, which is known as a repressor of flagellar, motility and chemotaxis genes, regulates biofilm formation and expression of type 1 fimbriae. Whole-genome expression profiling revealed that inactivation of lrhA results in an increased expression of structural components of type 1 fimbriae. In vitro, LrhA bound to the promoter regions of the two fim recombinases (FimB and FimE) that catalyse the inversion of the fimA promoter, and to the invertible element itself. Translational lacZ fusions with these genes and quantification of fimE transcript levels by real-time PCR showed that LrhA influences type 1 fimbrial phase variation, primarily via activation of FimE, which is required for the ON-to-OFF transition of the fim switch. Enhanced type 1 fimbrial expression as a result of lrhA disruption was confirmed by mannose-sensitive agglutination of yeast cells. Biofilm formation was stimulated by lrhA inactivation and completely suppressed upon LrhA overproduction. The effects of LrhA on biofilm formation were exerted via the changed levels of surface molecules, most probably both flagella and type 1 fimbriae. Together, the data show a role for LrhA as a repressor of type 1 fimbrial expression, and thus as a regulator of the initial stages of biofilm development and, presumably, bacterial adherence to epithelial host cells also. PMID:16207912

  1. Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX

    Directory of Open Access Journals (Sweden)

    S. S. Brown

    2013-05-01

    Full Text Available Organic compounds are a large component of aerosol mass, but organic aerosol (OA sources remain poorly characterized. Recent model studies have suggested nighttime oxidation of biogenic hydrocarbons as a potentially large OA source, but analysis of field measurements to test these predictions is sparse. We present nighttime vertical profiles of nitrogen oxides, ozone, VOCs and aerosol composition measured during low approaches of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large emissions of both biogenic hydrocarbons and nitrogen oxides. The latter serves as a source of the nitrate radical, NO3, a key nighttime oxidant. Biogenic VOCs (BVOC and urban pollutants were concentrated within the nocturnal boundary layer (NBL, which varied in depth from 100–400 m. Despite concentrated NOx at low altitude, ozone was never titrated to zero, resulting in rapid NO3 radical production rates of 0.2–2.7ppbv h-1 within the NBL. Monoterpenes and isoprene were frequently present within the NBL and underwent rapid oxidation (up to 1ppbv h−1, mainly by NO3 and to a lesser extent O3. Concurrent enhancement in organic and nitrate aerosol on several profiles was consistent with primary emissions and with secondary production from nighttime BVOC oxidation, with the latter equivalent to or slightly larger than the former. Ratios of organic aerosol to CO within the NBL ranged from 14 to 38 μg m−3 OA/ppmv CO. A box model simulation incorporating monoterpene emissions, oxidant formation rates and monoterpene SOA yields suggested overnight OA production of 0.5 to 9 μg m−3.

  2. THE CONTRADICTIONS OF THE FORMATION OF FUNCTIONAL AND TARGET REGULATION OF THE STOCK MARKET OF UKRAINE

    OpenAIRE

    A. Kalach

    2013-01-01

    The characteristics of formation of the inversion type of the stock market and its contradictions were investigated, the necessity of transition to a functional-target regulation of the stock market was proved the ways of optimization of the institutional system by integrating the functions of regulatory authorities were proposed.

  3. Formative Feedback to Transfer Self-Regulation of Task-Oriented Reading Strategies

    Science.gov (United States)

    Llorens, A. C.; Vidal-Abarca, E.; Cerdán, R.

    2016-01-01

    The study includes two experiments to analyse the effects of automatic formative feedback designed to promote the transfer of self-regulation of strategic decisions in task-oriented reading (e.g. answering questions from an available text). Secondary-school students read and answered multiple-choice comprehension questions from two texts having…

  4. Essential roles and regulation of the Legionella pneumophila collagen-like adhesin during biofilm formation.

    Science.gov (United States)

    Mallegol, Julia; Duncan, Carla; Prashar, Akriti; So, Jannice; Low, Donald E; Terebeznik, Mauricio; Guyard, Cyril

    2012-01-01

    Legionellosis is mostly caused by Legionella pneumophila (Lp) and is defined by a severe respiratory illness with a case fatality rate ranging from 5 to 80%. In a previous study, we showed that a glycosaminoglycan (GAG)-binding adhesin of Lp, named Lcl, is produced during legionellosis and is unique to the L. pneumophila species. Importantly, a mutant depleted in Lcl (Δlpg2644) is impaired in adhesion to GAGs and epithelial cells and in biofilm formation. Here, we examine the molecular function(s) of Lcl and the transcriptional regulation of its encoding gene during different stages of the biofilm development. We show that the collagen repeats and the C-terminal domains of Lcl are crucial for the production of biofilm. We present evidence that Lcl is involved in the early step of surface attachment but also in intercellular interactions. Furthermore, we address the relationship between Lcl gene regulation during biofilm formation and quorum sensing (QS). In a static biofilm assay, we show that Lcl is differentially regulated during growth phases and biofilm formation. Moreover, we show that the transcriptional regulation of lpg2644, mediated by a prototype of QS signaling homoserine lactone (3OC12-HSL), may play a role during the biofilm development. Thus, transcriptional down-regulation of lpg2644 may facilitate the dispersion of Lp to reinitiate biofilm colonization on a distal surface. PMID:23029523

  5. Essential roles and regulation of the Legionella pneumophila collagen-like adhesin during biofilm formation.

    Directory of Open Access Journals (Sweden)

    Julia Mallegol

    Full Text Available Legionellosis is mostly caused by Legionella pneumophila (Lp and is defined by a severe respiratory illness with a case fatality rate ranging from 5 to 80%. In a previous study, we showed that a glycosaminoglycan (GAG-binding adhesin of Lp, named Lcl, is produced during legionellosis and is unique to the L. pneumophila species. Importantly, a mutant depleted in Lcl (Δlpg2644 is impaired in adhesion to GAGs and epithelial cells and in biofilm formation. Here, we examine the molecular function(s of Lcl and the transcriptional regulation of its encoding gene during different stages of the biofilm development. We show that the collagen repeats and the C-terminal domains of Lcl are crucial for the production of biofilm. We present evidence that Lcl is involved in the early step of surface attachment but also in intercellular interactions. Furthermore, we address the relationship between Lcl gene regulation during biofilm formation and quorum sensing (QS. In a static biofilm assay, we show that Lcl is differentially regulated during growth phases and biofilm formation. Moreover, we show that the transcriptional regulation of lpg2644, mediated by a prototype of QS signaling homoserine lactone (3OC12-HSL, may play a role during the biofilm development. Thus, transcriptional down-regulation of lpg2644 may facilitate the dispersion of Lp to reinitiate biofilm colonization on a distal surface.

  6. Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets

    KAUST Repository

    SCHLEGEL, FABRICE

    2011-04-08

    Using high-resolution 3-D vortex simulations, this study seeks a mechanistic understanding of vorticity dynamics in transverse jets at a finite Reynolds number. A full no-slip boundary condition, rigorously formulated in terms of vorticity generation along the channel wall, captures unsteady interactions between the wall boundary layer and the jet - in particular, the separation of the wall boundary layer and its transport into the interior. For comparison, we also implement a reduced boundary condition that suppresses the separation of the wall boundary layer away from the jet nozzle. By contrasting results obtained with these two boundary conditions, we characterize near-field vortical structures formed as the wall boundary layer separates on the backside of the jet. Using various Eulerian and Lagrangian diagnostics, it is demonstrated that several near-wall vortical structures are formed as the wall boundary layer separates. The counter-rotating vortex pair, manifested by the presence of vortices aligned with the jet trajectory, is initiated closer to the jet exit. Moreover tornado-like wall-normal vortices originate from the separation of spanwise vorticity in the wall boundary layer at the side of the jet and from the entrainment of streamwise wall vortices in the recirculation zone on the lee side. These tornado-like vortices are absent in the case where separation is suppressed. Tornado-like vortices merge with counter-rotating vorticity originating in the jet shear layer, significantly increasing wall-normal circulation and causing deeper jet penetration into the crossflow stream. © 2011 Cambridge University Press.

  7. Original Mineralogy and Recognition of Upper Boundary of the Sarvak Formation Based on Geochemistry and Isotope Studies

    DEFF Research Database (Denmark)

    Asgari, M; Tahmasebi Poor, A; Barari, Amin

    2014-01-01

    Carbonate sequence of upper cretaceous (Cenomanian) of Sarvak Formation is a part of Bangestan Group with the thickness of 760m in Ahvaz oil field (well no. 63). This formation is overlain by the Kazhdumi Formation and is uncomfortably underlain by the Ilam Formation. In this study major and mino...

  8. Proteins with GGDEF and EAL domains regulate Pseudomonas putida biofilm formation and dispersal

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Tolker-Nielsen, Tim

    2006-01-01

    Microbial biofilm formation often causes problems in medical and industrial settings, and knowledge about the factors that are involved in biofilm development and dispersion is useful for creating strategies to control the processes. In this report, we present evidence that proteins with GGDEF...... and EAL domains are involved in the regulation of biofilm formation and biofilm dispersion in Pseudomonas putida. Overexpression in P. putida of the Escherichia coli YedQ protein, which contains a GGDEF domain, resulted in increased biofilm formation. Overexpression in P. putida of the E. coli Yhj......H protein, which contains an EAL domain, strongly inhibited biofilm formation. Induction of YhjH expression in P. putida cells situated in established biofilms led to rapid dispersion of the biofilms. These results support the emerging theme that GGDEF-domain and EAL-domain proteins are involved...

  9. Sprouty2 regulates endochondral bone formation by modulation of RTK and BMP signaling.

    Science.gov (United States)

    Joo, Adriane; Long, Roger; Cheng, Zhiqiang; Alexander, Courtney; Chang, Wenhan; Klein, Ophir D

    2016-07-01

    Skeletal development is regulated by the coordinated activity of signaling molecules that are both produced locally by cartilage and bone cells and also circulate systemically. During embryonic development and postnatal bone remodeling, receptor tyrosine kinase (RTK) superfamily members play critical roles in the proliferation, survival, and differentiation of chondrocytes, osteoblasts, osteoclasts, and other bone cells. Recently, several molecules that regulate RTK signaling have been identified, including the four members of the Sprouty (Spry) family (Spry1-4). We report that Spry2 plays an important role in regulation of endochondral bone formation. Mice in which the Spry2 gene has been deleted have defective chondrogenesis and endochondral bone formation, with a postnatal decrease in skeletal size and trabecular bone mass. In these constitutive Spry2 mutants, both chondrocytes and osteoblasts undergo increased cell proliferation and impaired terminal differentiation. Tissue-specific Spry2 deletion by either osteoblast- (Col1-Cre) or chondrocyte- (Col2-Cre) specific drivers led to decreased relative bone mass, demonstrating the critical role of Spry2 in both cell types. Molecular analyses of signaling pathways in Spry2(-/-) mice revealed an unexpected upregulation of BMP signaling and decrease in RTK signaling. These results identify Spry2 as a critical regulator of endochondral bone formation that modulates signaling in both osteoblast and chondrocyte lineages. PMID:27130872

  10. Role of SFP1 in the Regulation of Candida albicans Biofilm Formation.

    Directory of Open Access Journals (Sweden)

    Hsueh-Fen Chen

    Full Text Available Candida albicans is a major human fungal pathogen. One of the important features of C. albicans pathogenicity is the ability to form biofilms on mucosal surfaces and indwelling medical devices. Biofilm formation involves complex processes in C. albicans, including cell adhesion, filamentous growth, extracellular matrix secretion and cell dispersion. In this work, we characterized the role of the transcription factor Sfp1, particularly with respect to its function in the regulation of biofilm formation. The deletion of the SFP1 gene enhanced cell adhesion and biofilm formation in comparison to the wild-type strain. Interestingly, the sfp1-deleted mutant also exhibited an increase in the expression of the ALS1, ALS3 and HWP1 genes, which encode adhesin proteins. In addition, Sfp1 was demonstrated to function downstream of the Rhb1-TOR signaling pathway. Bcr1 and Efg1 are transcription factors that are critical for controlling biofilm formation, and Efg1 is also required for hyphal growth. Deleting either the BCR1 or EFG1 gene in the sfp1-null background led to reduced adhesin gene expression. As a result, the bcr1/sfp1 or efg1/sfp1 double deletion mutants exhibited dramatically reduced biofilm formation. The results indicated that Sfp1 negatively regulates the ALS1, ALS3 and HWP1 adhesin genes and that the repression of these genes is mediated by the inhibition of Bcr1 and Efg1.

  11. Aggresome formation is regulated by RanBPM through an interaction with HDAC6

    Directory of Open Access Journals (Sweden)

    Louisa M. Salemi

    2014-05-01

    Full Text Available In conditions of proteasomal impairment, the build-up of damaged or misfolded proteins activates a cellular response leading to the recruitment of damaged proteins into perinuclear aggregates called aggresomes. Aggresome formation involves the retrograde transport of cargo proteins along the microtubule network and is dependent on the histone deacetylase HDAC6. Here we show that ionizing radiation (IR promotes Ran-Binding Protein M (RanBPM relocalization into discrete perinuclear foci where it co-localizes with aggresome components ubiquitin, dynein and HDAC6, suggesting that the RanBPM perinuclear clusters correspond to aggresomes. RanBPM was also recruited to aggresomes following treatment with the proteasome inhibitor MG132 and the DNA-damaging agent etoposide. Strikingly, aggresome formation by HDAC6 was markedly impaired in RanBPM shRNA cells, but was restored by re-expression of RanBPM. RanBPM was found to interact with HDAC6 and to inhibit its deacetylase activity. This interaction was abrogated by a RanBPM deletion of its LisH/CTLH domain, which also prevented aggresome formation, suggesting that RanBPM promotes aggresome formation through an association with HDAC6. Our results suggest that RanBPM regulates HDAC6 activity and is a central regulator of aggresome formation.

  12. The human language-associated gene SRPX2 regulates synapse formation and vocalization in mice.

    Science.gov (United States)

    Sia, G M; Clem, R L; Huganir, R L

    2013-11-22

    Synapse formation in the developing brain depends on the coordinated activity of synaptogenic proteins, some of which have been implicated in a number of neurodevelopmental disorders. Here, we show that the sushi repeat-containing protein X-linked 2 (SRPX2) gene encodes a protein that promotes synaptogenesis in the cerebral cortex. In humans, SRPX2 is an epilepsy- and language-associated gene that is a target of the foxhead box protein P2 (FoxP2) transcription factor. We also show that FoxP2 modulates synapse formation through regulating SRPX2 levels and that SRPX2 reduction impairs development of ultrasonic vocalization in mice. Our results suggest FoxP2 modulates the development of neural circuits through regulating synaptogenesis and that SRPX2 is a synaptogenic factor that plays a role in the pathogenesis of language disorders. PMID:24179158

  13. Mosaic and Regulation Phenomena during the Early Formation of the Chick Blastoderm

    Directory of Open Access Journals (Sweden)

    Marc Callebaut

    2010-01-01

    Full Text Available After culturing symmetrically hemisectioned unincubated chicken blastoderms, asymmetric hemiembryos developed (indicating mosaic development. In the present study, we observed that after prolonged culture, the further asymmetric development (way with no possible return becomes profoundly disturbed, more particularly the Rauber's sickle-dependent phenomena: gastrulation and the formation of the coelomo-cardiovascular complex with absence of heart and pericard development. By contrast, the neural plate develops symmetrically. Asymmetrical ablation of Rauber's sickle and the neighboring upper layer results in the development of an apparently normal symmetrical embryo. Indeed, at the unoperated side, a normal half coelomo-cardiovascular system develops with a unilateral or bilateral heart tube and pericard formation (indicating regulation. Both regulation and mosaicism indicate that during normal early development, the interaction between the left and right sides of the caudal area centralis of the blastoderm is indispensable, depending on the spatial relationship between the elementary tissues (upper layer, Rauber's sickle, endophyll.

  14. Radiative effects of tropospheric aerosols on the evolution of the atmospheric boundary layer and its feedback on the haze formation

    Science.gov (United States)

    Wei, Chao; Su, Hang; Cheng, Yafang

    2016-04-01

    Planetary boundary layer (PBL) plays a key role in air pollution dispersion and influences day-to-day air quality. Some studies suggest that high aerosol loadings during severe haze events may modify PBL dynamics by radiative effects and hence enhance the development of haze. This study mainly investigates the radiative effects of tropospheric aerosols on the evolution of the atmospheric boundary layer by conducting simulations with Weather Research and Forecasting single-column model (WRF-SCM). We find that high aerosol loading in PBL depressed boundary layer height (PBLH). But the magnitude of the changes of PBLH after adding aerosol loadings in our simulations are small and can't explain extreme high aerosol concentrations observed. We also investigate the impacts of the initial temperature and moisture profiles on the evolution of PBL. Our studies show that the impact of the vertical profile of moisture is comparable with aerosol effects.

  15. ZAP-70 kinase regulates HIV cell-to-cell spread and virological synapse formation

    OpenAIRE

    Sol-Foulon, Nathalie; Sourisseau, Marion; Porrot, Françoise; Thoulouze, Maria-Isabel; Trouillet, Céline; Nobile, Cinzia; Blanchet, Fabien; Di Bartolo, Vincenzo; Noraz, Nelly; Taylor, Naomi; Alcover, Andres; Hivroz, Claire; Schwartz, Olivier

    2007-01-01

    HIV efficiently spreads in lymphocytes, likely through virological synapses (VSs). These cell–cell junctions share some characteristics with immunological synapses, but cellular proteins required for their constitution remain poorly characterized. We have examined here the role of ZAP-70, a key kinase regulating T-cell activation and immunological synapse formation, in HIV replication. In lymphocytes deficient for ZAP-70, or expressing a kinase-dead mutant of the protein, HIV replication was ...

  16. Feedback Regulated Star Formation: Implications for the Kennicutt-Schmidt Law

    CERN Document Server

    Dib, Sami

    2011-01-01

    We derive a metallicity dependent relation between the surface density of the star formation rate (Sigma_{SFR}) and the gas surface density (Sigma_{g}) in a feedback regulated model of star formation in galactic disks. In this model, star formation occurs in gravitationally bound protocluster clumps embedded in larger giant molecular clouds with the protocluster clump mass function following a power law function with a slope of -2 Metallicity dependent feedback is generated by the winds of OB stars (M > 5 Msol) that form in the clumps. The quenching of star formation in clumps of decreasing metallicity occurs at later epochs due to weaker wind luminosities, thus resulting in higher final star formation efficiencies (SFE_{exp}). By combining SFE_{exp} with the timescales on which gas expulsion occurs, we derive the metallicity dependent star formation rate per unit time in this model as a function of Sigma_{g}. This is combined with the molecular gas fraction in order to derive the global dependence of Sigma_{...

  17. Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation

    Directory of Open Access Journals (Sweden)

    Kouki eYoshida

    2013-10-01

    Full Text Available Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs can regulate secondary wall formation in rice (Oryza sativa and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S has very low transcriptional activation ability, but the longer protein (OsSWN2L and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.

  18. Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation.

    Science.gov (United States)

    Yoshida, Kouki; Sakamoto, Shingo; Kawai, Tetsushi; Kobayashi, Yoshinori; Sato, Kazuhito; Ichinose, Yasunori; Yaoi, Katsuro; Akiyoshi-Endo, Miho; Sato, Hiroko; Takamizo, Tadashi; Ohme-Takagi, Masaru; Mitsuda, Nobutaka

    2013-01-01

    Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs) can regulate secondary wall formation in rice (Oryza sativa) and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S) has very low transcriptional activation ability, but the longer protein (OsSWN2L) and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions) due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications. PMID:24098302

  19. New insights on molecular regulation of biofilm formation in plant-associated bacteria

    Institute of Scientific and Technical Information of China (English)

    Luisa F. Castiblanco; George W. Sundin

    2016-01-01

    Biofilms are complex bacterial assemblages with a defined three-dimensional architecture, attached to solid surfaces, and surrounded by a self-produced matrix generally composed of exopolysaccharides, proteins, lipids and extrac-ellular DNA. Biofilm formation has evolved as an adaptive strategy of bacteria to cope with harsh environmental conditions as well as to establish antagonistic or beneficial interactions with their host. Plant-associated bacteria attach and form biofilms on different tissues including leaves, stems, vasculature, seeds and roots. In this review, we examine the formation of biofilms from the plant-associated bacterial perspective and detail the recently-described mechanisms of genetic regulation used by these organisms to orchestrate biofilm formation on plant surfaces. In addition, we describe plant host signals that bacterial pathogens recognize to activate the transition from a planktonic lifestyle to multi-cellular behavior.

  20. Afadin regulates puncta adherentia junction formation and presynaptic differentiation in hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Daisaku Toyoshima

    Full Text Available The formation and remodeling of mossy fiber-CA3 pyramidal cell synapses in the stratum lucidum of the hippocampus are implicated in the cellular basis of learning and memory. Afadin and its binding cell adhesion molecules, nectin-1 and nectin-3, together with N-cadherin, are concentrated at puncta adherentia junctions (PAJs in these synapses. Here, we investigated the roles of afadin in PAJ formation and presynaptic differentiation in mossy fiber-CA3 pyramidal cell synapses. At these synapses in the mice in which the afadin gene was conditionally inactivated before synaptogenesis by using nestin-Cre mice, the immunofluorescence signals for the PAJ components, nectin-1, nectin-3 and N-cadherin, disappeared almost completely, while those for the presynaptic components, VGLUT1 and bassoon, were markedly decreased. In addition, these signals were significantly decreased in cultured afadin-deficient hippocampal neurons. Furthermore, the interevent interval of miniature excitatory postsynaptic currents was prolonged in the cultured afadin-deficient hippocampal neurons compared with control neurons, indicating that presynaptic functions were suppressed or a number of synapse was reduced in the afadin-deficient neurons. Analyses of presynaptic vesicle recycling and paired recordings revealed that the cultured afadin-deficient neurons showed impaired presynaptic functions. These results indicate that afadin regulates both PAJ formation and presynaptic differentiation in most mossy fiber-CA3 pyramidal cell synapses, while in a considerable population of these neurons, afadin regulates only PAJ formation but not presynaptic differentiation.

  1. Afadin Regulates Puncta Adherentia Junction Formation and Presynaptic Differentiation in Hippocampal Neurons

    Science.gov (United States)

    Toyoshima, Daisaku; Mandai, Kenji; Maruo, Tomohiko; Supriyanto, Irwan; Togashi, Hideru; Inoue, Takahito; Mori, Masahiro; Takai, Yoshimi

    2014-01-01

    The formation and remodeling of mossy fiber-CA3 pyramidal cell synapses in the stratum lucidum of the hippocampus are implicated in the cellular basis of learning and memory. Afadin and its binding cell adhesion molecules, nectin-1 and nectin-3, together with N-cadherin, are concentrated at puncta adherentia junctions (PAJs) in these synapses. Here, we investigated the roles of afadin in PAJ formation and presynaptic differentiation in mossy fiber-CA3 pyramidal cell synapses. At these synapses in the mice in which the afadin gene was conditionally inactivated before synaptogenesis by using nestin-Cre mice, the immunofluorescence signals for the PAJ components, nectin-1, nectin-3 and N-cadherin, disappeared almost completely, while those for the presynaptic components, VGLUT1 and bassoon, were markedly decreased. In addition, these signals were significantly decreased in cultured afadin-deficient hippocampal neurons. Furthermore, the interevent interval of miniature excitatory postsynaptic currents was prolonged in the cultured afadin-deficient hippocampal neurons compared with control neurons, indicating that presynaptic functions were suppressed or a number of synapse was reduced in the afadin-deficient neurons. Analyses of presynaptic vesicle recycling and paired recordings revealed that the cultured afadin-deficient neurons showed impaired presynaptic functions. These results indicate that afadin regulates both PAJ formation and presynaptic differentiation in most mossy fiber-CA3 pyramidal cell synapses, while in a considerable population of these neurons, afadin regulates only PAJ formation but not presynaptic differentiation. PMID:24587018

  2. Focus on Formative Feedbackcommunication and self-regulated learning – a study in compulsory schools

    DEFF Research Database (Denmark)

    Kirkegaard, Preben Olund

    2016-01-01

    This study addresses the conceptual challenge of providing students in compulsory schools with good quality formative feedback to enhance self-regulated learning in social interactions. Resent educational research indicates that social communicative interactions in the classroom, with a focus...... qualitative data from video recorded teaching sessions and student group interviews. Methodologically we are inspired by the ethnographical classroom research method. The empirical basis for studying these aspects is data from two compulsory schools in Denmark. This study is a work in progress. Our findings...... suggest that students can develop self-regulation skill by focusing on three key aspects: 1) Maintain focus on meta-reflection, 2) maintain focus on the construction of meaning and 3) rubrics can support self-regulated learning in group work....

  3. Lipid nanotube formation using space-regulated electric field above interdigitated electrodes.

    Science.gov (United States)

    Bi, Hongmei; Fu, Dingguo; Wang, Lei; Han, Xiaojun

    2014-04-22

    Lipid nanotubes have great potential in biology and nanotechnology. Here we demonstrate a method to form lipid nanotubes using space-regulated AC electric fields above coplanar interdigitated electrodes. The AC electric field distribution can be regulated by solution height above the electrodes. The ratio of field component in x axis (Ex) to field component in z axis (Ez) increases dramatically at solution height below 50 μm; therefore, at lower solution height, the force from Ex predominantly drives lipids to form lipid nanotubes along with the electric field direction. The forces exerted on the lipid nanotube during its formation were analyzed in detail, and an equation was obtained to describe the relationship among nanotube length and field frequency, amplitude, and time. We believe that the presented approach opens a way to design and prepare nanoscale materials with unique structural and functional properties using space-regulated electric fields.

  4. The CUP-SHAPED COTYLEDON3 gene is required for boundary and shoot meristem formation in Arabidopsis

    DEFF Research Database (Denmark)

    Vroemen, Casper W; Mordhorst, Andreas P; Albrecht, Cathy;

    2003-01-01

    revealing an even higher degree of redundancy in this class of genes than was thought previously. The CUC3 expression pattern, the cuc3 phenotypes, and CUC3 expression in a series of shoot meristem mutants and transgenes suggest a primary role for CUC3 in the establishment of boundaries that contain cells...

  5. Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; /KIPAC, Menlo Park /Stanford U., Phys.Dept.; Li, Zhi-Yun; /Virginia U., Astron. Dept.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys.Dept.; Nakamura, Fumitaka; /Niigata U.

    2010-02-15

    We investigate massive star formation in turbulent, magnetized, parsec-scale clumps of molecular clouds including protostellar outflow feedback using three dimensional numerical simulations of effective resolution 2048{sup 3}. The calculations are carried out using a block structured adaptive mesh refinement code that solves the ideal MHD equations including self-gravity and implements accreting sink particles. We find that, in the absence of regulation by magnetic fields and outflow feedback, massive stars form readily in a turbulent, moderately condensed clump of {approx} 1,600 M{sub {circle_dot}} (containing {approx} 10{sup 2} initial Jeans masses), along with a cluster of hundreds of lower mass stars. The massive stars are fed at high rates by (1) transient dense filaments produced by large-scale turbulent compression at early times, and (2) by the clump-wide global collapse resulting from turbulence decay at late times. In both cases, the bulk of the massive star's mass is supplied from outside a 0.1 pc-sized 'core' that surrounds the star. In our simulation, the massive star is clump-fed rather than core-fed. The need for large-scale feeding makes the massive star formation prone to regulation by outflow feedback, which directly opposes the feeding processes. The outflows reduce the mass accretion rates onto the massive stars by breaking up the dense filaments that feed the massive star formation at early times, and by collectively slowing down the global collapse that fuel the massive star formation at late times. The latter is aided by a moderate magnetic field of strength in the observed range (corresponding to a dimensionless clump mass-to-flux ratio {lambda} {approx} a few); the field allows the outflow momenta to be deposited more efficiently inside the clump. We conclude that the massive star formation in our simulated turbulent, magnetized, parsec-scale clump is outflow-regulated and clump-fed (ORCF for short). An important implication

  6. Major contribution of neutral clusters to new particle formation at the interface between the boundary layer and the free troposphere

    OpenAIRE

    Rose, C; Sellegri, K.; Asmi, E.; Hervo, M.; Freney, E.; Colomb, A.; Junninen, H.; J. Duplissy; Sipilä, M.; Kontkanen, J.; Lehtipalo, K.; M. Kulmala

    2015-01-01

    The formation of new aerosol particles in the atmosphere is a key process influencing the aerosol number concentration as well as the climate, in particular at high altitude, where the newly formed particles directly influence cloud formation. However, free tropospheric new particle formation (NPF) is poorly documented due to logistic limitations and complex atmospheric dynamics around high-altitude stations that make the observation of this day-time process challenging. Rec...

  7. A novel genetic mechanism regulates dorsolateral hinge-point formation during zebrafish cranial neurulation.

    Science.gov (United States)

    Nyholm, Molly K; Abdelilah-Seyfried, Salim; Grinblat, Yevgenya

    2009-06-15

    During neurulation, vertebrate embryos form a neural tube (NT), the rudiment of the central nervous system. In mammals and birds, a key step in cranial NT morphogenesis is dorsolateral hinge-point (DLHP) bending, which requires an apical actomyosin network. The mechanism of DLHP formation is poorly understood, although several essential genes have been identified, among them Zic2, which encodes a zinc-finger transcription factor. We found that DLHP formation in the zebrafish midbrain also requires actomyosin and Zic function. Given this conservation, we used the zebrafish to study how genes encoding Zic proteins regulate DLHP formation. We demonstrate that the ventral zic2a expression border predicts DLHP position. Using morpholino (MO) knockdown, we show zic2a and zic5 are required for apical F-actin and active myosin II localization and junction integrity. Furthermore, myosin II activity can function upstream of junction integrity during DLHP formation, and canonical Wnt signaling, an activator of zic gene transcription, is necessary for apical active myosin II localization, junction integrity and DLHP formation. We conclude that zic genes act downstream of Wnt signaling to control cytoskeletal organization, and possibly adhesion, during neurulation. This study identifies zic2a and zic5 as crucial players in the genetic network linking patterned gene expression to morphogenetic changes during neurulation, and strengthens the utility of the zebrafish midbrain as a NT morphogenesis model.

  8. Dynamics of ordering in highly degenerate models with anisotropic grain-boundary potential: Effects of temperature and vortex formation

    Science.gov (United States)

    Jeppesen, Claus; Flyvbjerg, Henrik; Mouritsen, Ole G.

    1989-11-01

    Monte Carlo computer-simulation techniques are used to elucidate the equilibrium phase behavior as well as the late-stage ordering dynamics of some two-dimensional models with ground-state ordering of a high degeneracy Q. The models are Q-state Potts models with anisotropic grain-boundary potential on triangular lattices-essentially clock models, except that the potential is not a cosine, but a sine function of the angle between neighboring grain orientations. For not too small Q, these models display two thermally driven phase transitions, one which takes the system from a low-temperature Potts-ordered phase to an intermediate phase which lacks conventional long-range order, and another transition which takes the system to the high-temperature disordered phase. The linear nature of the sine potential used makes it a marginal case in the sense that it favors neither hard domain boundaries, like the standard Potts models do, nor a wetting of the boundaries, as the standard clock models do. Thermal fluctuations nevertheless cause wetting to occur for not too small temperatures. Specifically, we have studied models with Q=12 and 48. The models are quenched from infinity to zero as well as finite temperatures within the two low-temperature phases. The order parameter is a nonconserved quantity during these quenches. The nonequilibrium ordering process subsequent to the quench is studied as a function of time by calculating the interfacial energy, ΔE, associated with the entire grain-boundary network. The time evolution of this quantity is shown to obey the growth law, ΔE(t)~t-n, over an extended time range at late times. It is found that the zero-temperature dynamics is characterized by a special exponent value which for the Q=48 model is n~=0.25 in accordance with earlier work. However, for quenches to finite temperatures in the Potts-ordered phase there is a distinct crossover to the classical Lifshitz-Allen-Cahn exponent value, n=(1/2, for both values of Q. This

  9. Mechanism of regulation of the formate-hydrogenlyase pathway by oxygen, nitrate, and pH: definition of the formate regulon.

    Science.gov (United States)

    Rossmann, R; Sawers, G; Böck, A

    1991-11-01

    The products of a minimum of 15 genes are required for the synthesis of an active formate-hydrogenlyase (FHL) system in Escherichia coli. All are co-ordinately regulated in response to variations in the oxygen and nitrate concentration and the pH of the culture medium. Formate is obligately required for transcriptional activation of these genes. Analysis of the transcription of one of these genes, hycB linked to the lacZ reporter gene, revealed that oxygen and nitrate repression of transcription could be relieved completely, or partially in the case of nitrate, either by the addition of formate to the medium or by increasing the copy number of the gene encoding the transcriptional activator (fhlA) of this regulon. These studies uncovered a further level of regulation in which the transcription of hycB was reduced in cells grown on glucose. This effect was most clearly seen in aerobically grown cells when formate was added externally. Addition of cAMP overcame this glucose repression, which could be shown to be mediated by the cAMP receptor protein. These results would be consistent with the transport of formate being regulated by catabolite repression. Moreover, the repression of transcription through high pH also could be partially overcome by addition of increasing concentrations of formate to the medium, again being consistent with regulation at the level of formate import and export. Taken together, all these observations indicate that it is the intracellular level of formate that determines the transcription of the genes of the formate regulon by FhlA. This represents a novel positive feedback mechanism in which the activator of a regulon induces its own synthesis in response to increases in the concentration of the catabolic substrate, and this in turn is governed by the relative affinities of FhlA and the three formate dehydrogenase isoenzymes for formate. PMID:1779767

  10. Dynamic O-GlcNAc modification regulates CREB-mediated gene expression and memory formation.

    Science.gov (United States)

    Rexach, Jessica E; Clark, Peter M; Mason, Daniel E; Neve, Rachael L; Peters, Eric C; Hsieh-Wilson, Linda C

    2012-01-22

    The transcription factor cyclic AMP-response element binding protein (CREB) is a key regulator of many neuronal processes, including brain development, circadian rhythm and long-term memory. Studies of CREB have focused on its phosphorylation, although the diversity of CREB functions in the brain suggests additional forms of regulation. Here we expand on a chemoenzymatic strategy for quantifying glycosylation stoichiometries to characterize the functional roles of CREB glycosylation in neurons. We show that CREB is dynamically modified with an O-linked β-N-acetyl-D-glucosamine sugar in response to neuronal activity and that glycosylation represses CREB-dependent transcription by impairing its association with CREB-regulated transcription coactivator (CRTC; also known as transducer of regulated CREB activity). Blocking glycosylation of CREB alters cellular function and behavioral plasticity, enhancing both axonal and dendritic growth and long-term memory consolidation. Our findings demonstrate a new role for O-glycosylation in memory formation and provide a mechanistic understanding of how glycosylation contributes to critical neuronal functions. Moreover, we identify a previously unknown mechanism for the regulation of activity-dependent gene expression, neural development and memory.

  11. TGF-b/BMP signaling and other molecular events:regulation of osteoblastogenesis and bone formation

    Institute of Scientific and Technical Information of China (English)

    Md Shaifur Rahman; Naznin Akhtar; Hossen Mohammad Jamil; Rajat Suvra Banik; Sikder M Asaduzzaman

    2015-01-01

    Transforming growth factor-beta (TGF-b)/bone morphogenetic protein (BMP) plays a fundamental role in the regulation of bone organogenesis through the activation of receptor serine/threonine kinases. Perturbations of TGF-b/BMP activity are almost invariably linked to a wide variety of clinical outcomes, i.e., skeletal, extra skeletal anomalies, autoimmune, cancer, and cardiovascular diseases. Phosphorylation of TGF-b (I/II) or BMP receptors activates intracellular downstream Smads, the transducer of TGF-b/BMP signals. This signaling is modulated by various factors and pathways, including transcription factor Runx2. The signaling network in skeletal development and bone formation is overwhelmingly complex and highly time and space specific. Additive, positive, negative, or synergistic effects are observed when TGF-b/BMP interacts with the pathways of MAPK, Wnt, Hedgehog (Hh), Notch, Akt/mTOR, and miRNA to regulate the effects of BMP-induced signaling in bone dynamics. Accumulating evidence indicates that Runx2 is the key integrator, whereas Hh is a possible modulator, miRNAs are regulators, and b-catenin is a mediator/regulator within the extensive intracellular network. This review focuses on the activation of BMP signaling and interaction with other regulatory components and pathways highlighting the molecular mechanisms regarding TGF-b/BMP function and regulation that could allow understanding the complexity of bone tissue dynamics.

  12. Dynamics of ordering in highly degenerate models with anisotropic grain-boundary potential: Effects of temperature and vortex formation

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Flyvbjerg, Henrik; Mouritsen, Ole G.

    1989-01-01

    universality class, and that all models with nonconserved order parameter, independent of ordering degeneracy and softness and origin of domain boundaries, obey the classical growth law at finite temperatures. In quenches to the Potts-ordered phase vortices and antivortices occur and annihilate mutually...... without pinning the ordering process. The ordering dynamics for quenches into the intermediate phase is also found to be described by an effectively algebraic growth law....

  13. Formation of Graphene Grain Boundaries on Cu(100) Surface and a Route Towards Their Elimination in Chemical Vapor Deposition Growth

    OpenAIRE

    Qinghong Yuan; Guangyao Song; Deyan Sun; Feng Ding

    2014-01-01

    Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface — Cu(100) surface, is explored by density functional theory (DFT) calculatio...

  14. Reggies/flotillins regulate E-cadherin-mediated cell contact formation by affecting EGFR trafficking.

    Science.gov (United States)

    Solis, Gonzalo P; Schrock, Yvonne; Hülsbusch, Nikola; Wiechers, Marianne; Plattner, Helmut; Stuermer, Claudia A O

    2012-05-01

    The reggie/flotillin proteins are implicated in membrane trafficking and, together with the cellular prion protein (PrP), in the recruitment of E-cadherin to cell contact sites. Here, we demonstrate that reggies, as well as PrP down-regulation, in epithelial A431 cells cause overlapping processes and abnormal formation of adherens junctions (AJs). This defect in cell adhesion results from reggie effects on Src tyrosine kinases and epidermal growth factor receptor (EGFR): loss of reggies reduces Src activation and EGFR phosphorylation at residues targeted by Src and c-cbl and leads to increased surface exposure of EGFR by blocking its internalization. The prolonged EGFR signaling at the plasma membrane enhances cell motility and macropinocytosis, by which junction-associated E-cadherin is internalized and recycled back to AJs. Accordingly, blockage of EGFR signaling or macropinocytosis in reggie-deficient cells restores normal AJ formation. Thus, by promoting EGFR internalization, reggies restrict the EGFR signaling involved in E-cadherin macropinocytosis and recycling and regulate AJ formation and dynamics and thereby cell adhesion.

  15. A Genome-Wide Association Study for Regulators of Micronucleus Formation in Mice.

    Science.gov (United States)

    McIntyre, Rebecca E; Nicod, Jérôme; Robles-Espinoza, Carla Daniela; Maciejowski, John; Cai, Na; Hill, Jennifer; Verstraten, Ruth; Iyer, Vivek; Rust, Alistair G; Balmus, Gabriel; Mott, Richard; Flint, Jonathan; Adams, David J

    2016-01-01

    In mammals the regulation of genomic instability plays a key role in tumor suppression and also controls genome plasticity, which is important for recombination during the processes of immunity and meiosis. Most studies to identify regulators of genomic instability have been performed in cells in culture or in systems that report on gross rearrangements of the genome, yet subtle differences in the level of genomic instability can contribute to whole organism phenotypes such as tumor predisposition. Here we performed a genome-wide association study in a population of 1379 outbred Crl:CFW(SW)-US_P08 mice to dissect the genetic landscape of micronucleus formation, a biomarker of chromosomal breaks, whole chromosome loss, and extranuclear DNA. Variation in micronucleus levels is a complex trait with a genome-wide heritability of 53.1%. We identify seven loci influencing micronucleus formation (false discovery rate locus. Intriguingly at several loci we find evidence for sexual dimorphism in micronucleus formation, with a locus on chromosome 11 being specific to males. PMID:27233670

  16. Shp2 in forebrain neurons regulates synaptic plasticity, locomotion, and memory formation in mice.

    Science.gov (United States)

    Kusakari, Shinya; Saitow, Fumihito; Ago, Yukio; Shibasaki, Koji; Sato-Hashimoto, Miho; Matsuzaki, Yasunori; Kotani, Takenori; Murata, Yoji; Hirai, Hirokazu; Matsuda, Toshio; Suzuki, Hidenori; Matozaki, Takashi; Ohnishi, Hiroshi

    2015-05-01

    Shp2 (Src homology 2 domain-containing protein tyrosine phosphatase 2) regulates neural cell differentiation. It is also expressed in postmitotic neurons, however, and mutations of Shp2 are associated with clinical syndromes characterized by mental retardation. Here we show that conditional-knockout (cKO) mice lacking Shp2 specifically in postmitotic forebrain neurons manifest abnormal behavior, including hyperactivity. Novelty-induced expression of immediate-early genes and activation of extracellular-signal-regulated kinase (Erk) were attenuated in the cerebral cortex and hippocampus of Shp2 cKO mice, suggestive of reduced neuronal activity. In contrast, ablation of Shp2 enhanced high-K(+)-induced Erk activation in both cultured cortical neurons and synaptosomes, whereas it inhibited that induced by brain-derived growth factor in cultured neurons. Posttetanic potentiation and paired-pulse facilitation were attenuated and enhanced, respectively, in hippocampal slices from Shp2 cKO mice. The mutant mice also manifested transient impairment of memory formation in the Morris water maze. Our data suggest that Shp2 contributes to regulation of Erk activation and synaptic plasticity in postmitotic forebrain neurons and thereby controls locomotor activity and memory formation.

  17. MST12 regulates infectious growth but not appressorium formation in the rice blast fungus Magnaporthe grisea.

    Science.gov (United States)

    Park, Gyungsoon; Xue, Chaoyang; Zheng, Li; Lam, Stephen; Xu, Jin-Rong

    2002-03-01

    In the rice blast fungus Magnaporthe grisea, a mitogen-activated protein kinase gene, PMK1, is known to regulate appressorium formation and infectious hyphae growth. Since PMK1 is homologous to the FUS3 and KSS1 genes that regulate the transcription factor STE12 in yeast, we functionally characterized the STE12 homologue in M. grisea (MST12). A polymerase chain reaction-based approach was used to isolate the MST12 gene that is homologous to yeast STE12. Four mst12 deletion mutants were isolated by gene replacement. No obvious defect in vegetative growth, conidiation, or conidia germination was observed in mst12 mutants. However, mst12 mutants were nonpathogenic on rice and barley leaves. In contrast to pmk1 mutants that did not form appressoria, mst12 mutants produced typical dome-shaped and melanized appressoria. However, the appressoria formed by mst12 mutants failed to penetrate onion epidermal cells. When inoculated through wound sites, mst12 mutants failed to cause spreading lesions and appeared to be defective in infectious growth. These data indicate that MST12 may function downstream of PMK1 to regulate genes involved in infectious hyphae growth. A transcription factor or factors other than MST12 must exist in M. grisea and function downstream from PMK1 for appressorium formation. PMID:11952120

  18. Palynology of the Lost Branch Formation of Kansas - New insights on the major floral transition at the Middle-Upper Pennsylvanian boundary

    Science.gov (United States)

    Peppers, R.A.

    1997-01-01

    Palynological assemblages from two outcrops of the upper part of the Memorial Formation, the Lost Branch Formation, and the overlying Hepler unit in Kansas were examined to discover which stratigraphic interval marks the change from the lycopod-dominated coal swamp floras of Middle Pennsylvanian (Westphalian D) age to the fern-dominated coal swamp floras of Late Pennsylvanian (Stephanian) age. The Lost Branch Formation underlies the Pleasanton Group, whose base is recognized as the Middle-Upper Pennsylvanian boundary in the Midcontinent. The outcrops include the youngest Middle Pennsylvanian coal (Dawson), just below the Lost Branch Formation, and the oldest Upper Pennsylvanian coal ('Hepler') within the Pleasanton Group. Lycospora dominates the spore assemblage in the Middle Pennsylvanian (Desmoinesian) Dawson coal in the Memorial Shale and is abundant in shale between the coal and just below the Glenpool limestone bed at the top of the Lost Branch Formation. It is rare between the limestone and the Upper Pennsylvanian (Missourian) 'Hepler' coal. Granasporites medius and Thymospora pseudothiessenii disappear below the limestone. The 'Hepler' coal is dominated by fern and seed fern spores Cyclogranisporites and Apiculatasporites, and the sphenopsid spore Calamospora is third in abundance. Florinites, Potonieisporites and other gymnospermic monosaccate pollen are abundant between the two coals. Bisaccate conifer-like pollen, such as Protohaploxipinus, are most common between the Dawson coal and Glenpool limestone, but Wilsonites, which is thought to have been produced by seed ferns, is very abundant from the Glenpool limestone to the 'Hepler' coal. On the basis of macroinvertebrate evidence, the Glenpool limestone is Middle Pennsylvanian in age, but the palynological evidence indicates that the floral change took place slightly before deposition of the limestone. Thus, the major change in climate that occurred near the Middle-Upper Pennsylvanian boundary apparently

  19. Artificial induction of Sox21 regulates sensory cell formation in the embryonic chicken inner ear.

    Directory of Open Access Journals (Sweden)

    Stephen D Freeman

    Full Text Available During embryonic development, hair cells and support cells in the sensory epithelia of the inner ear derive from progenitors that express Sox2, a member of the SoxB1 family of transcription factors. Sox2 is essential for sensory specification, but high levels of Sox2 expression appear to inhibit hair cell differentiation, suggesting that factors regulating Sox2 activity could be critical for both processes. Antagonistic interactions between SoxB1 and SoxB2 factors are known to regulate cell differentiation in neural tissue, which led us to investigate the potential roles of the SoxB2 member Sox21 during chicken inner ear development. Sox21 is normally expressed by sensory progenitors within vestibular and auditory regions of the early embryonic chicken inner ear. At later stages, Sox21 is differentially expressed in the vestibular and auditory organs. Sox21 is restricted to the support cell layer of the auditory epithelium, while it is enriched in the hair cell layer of the vestibular organs. To test Sox21 function, we used two temporally distinct gain-of-function approaches. Sustained over-expression of Sox21 from early developmental stages prevented prosensory specification, and abolished the formation of both hair cells and support cells. However, later induction of Sox21 expression at the time of hair cell formation in organotypic cultures of vestibular epithelia inhibited endogenous Sox2 expression and Notch activity, and biased progenitor cells towards a hair cell fate. Interestingly, Sox21 did not promote hair cell differentiation in the immature auditory epithelium, which fits with the expression of endogenous Sox21 within mature support cells in this tissue. These results suggest that interactions among endogenous SoxB family transcription factors may regulate sensory cell formation in the inner ear, but in a context-dependent manner.

  20. Inhibition of proliferation by PERK regulates mammary acinar morphogenesis and tumor formation.

    Directory of Open Access Journals (Sweden)

    Sharon J Sequeira

    Full Text Available Endoplasmic reticulum (ER stress signaling can be mediated by the ER kinase PERK, which phosphorylates its substrate eIF2alpha. This in turn, results in translational repression and the activation of downstream programs that can limit cell growth through cell cycle arrest and/or apoptosis. These responses can also be initiated by perturbations in cell adhesion. Thus, we hypothesized that adhesion-dependent regulation of PERK signaling might determine cell fate. We tested this hypothesis in a model of mammary acini development, a morphogenetic process regulated in part by adhesion signaling. Here we report a novel role for PERK in limiting MCF10A mammary epithelial cell proliferation during acinar morphogenesis in 3D Matrigel culture as well as in preventing mammary tumor formation in vivo. We show that loss of adhesion to a suitable substratum induces PERK-dependent phosphorylation of eIF2alpha and selective upregulation of ATF4 and GADD153. Further, inhibition of endogenous PERK signaling during acinar morphogenesis, using two dominant-negative PERK mutants (PERK-DeltaC or PERK-K618A, does not affect apoptosis but results instead in hyper-proliferative and enlarged lumen-filled acini, devoid of proper architecture. This phenotype correlated with an adhesion-dependent increase in translation initiation, Ki67 staining and upregulation of Laminin-5, ErbB1 and ErbB2 expression. More importantly, the MCF10A cells expressing PERKDeltaC, but not a vector control, were tumorigenic in vivo upon orthotopic implantation in denuded mouse mammary fat pads. Our results reveal that the PERK pathway is responsive to adhesion-regulated signals and that it is essential for proper acinar morphogenesis and in preventing mammary tumor formation. The possibility that deficiencies in PERK signaling could lead to hyperproliferation of the mammary epithelium and increase the likelihood of tumor formation, is of significance to the understanding of breast cancer.

  1. Postgraduate education and research in Brazil: regulation and reconfiguration processes of academic work formation and production

    Directory of Open Access Journals (Sweden)

    João Ferreira de Oliveira

    2015-07-01

    Full Text Available This text analyses some of the processes of formation and production regulation and reconfiguration of the scholarly work in Brazil. Initially we examine the context and meaning of knowledge production in times of flexible accumulation, as well as the current landscape of Postgraduate education in the country. We seek to understand how public policies in the area, particularly the actions of evaluation and promotion, and the new modus operandi of the Postgraduate study and research organization have been reconfiguring the work production of teaching and students within the programs, especially in education. Above all, we seek to highlight the role of promotion and evaluation agencies, increasingly committed to a vision of expansion that drives the production of knowledge associated with demands of economic-productivity, rather than a consistent formative project that would result in a significant advancement in the production and dissemination of knowledge in the different areas.

  2. Self-regulation of charged defect compensation and formation energy pinning in semiconductors

    Science.gov (United States)

    Yang, Ji-Hui; Yin, Wan-Jian; Park, Ji-Sang; Wei, Su-Huai

    2015-11-01

    Current theoretical analyses of defect properties without solving the detailed balance equations often estimate Fermi-level pinning position by omitting free carriers and assume defect concentrations can be always tuned by atomic chemical potentials. This could be misleading in some circumstance. Here we clarify that: (1) Because the Fermi-level pinning is determined not only by defect states but also by free carriers from band-edge states, band-edge states should be treated explicitly in the same footing as the defect states in practice; (2) defect formation energy, thus defect density, could be pinned and independent on atomic chemical potentials due to the entanglement of atomic chemical potentials and Fermi energy, in contrast to the usual expectation that defect formation energy can always be tuned by varying the atomic chemical potentials; and (3) the charged defect compensation behavior, i.e., most of donors are compensated by acceptors or vice versa, is self-regulated when defect formation energies are pinned. The last two phenomena are more dominant in wide-gap semiconductors or when the defect formation energies are small. Using NaCl and CH3NH3PbI3 as examples, we illustrate these unexpected behaviors. Our analysis thus provides new insights that enrich the understanding of the defect physics in semiconductors and insulators.

  3. NRP1 Regulates CDC42 Activation to Promote Filopodia Formation in Endothelial Tip Cells

    Directory of Open Access Journals (Sweden)

    Alessandro Fantin

    2015-06-01

    Full Text Available Sprouting blood vessels are led by filopodia-studded endothelial tip cells that respond to angiogenic signals. Mosaic lineage tracing previously revealed that NRP1 is essential for tip cell function, although its mechanistic role in tip cells remains poorly defined. Here, we show that NRP1 is dispensable for genetic tip cell identity. Instead, we find that NRP1 is essential to form the filopodial bursts that distinguish tip cells morphologically from neighboring stalk cells, because it enables the extracellular matrix (ECM-induced activation of CDC42, a key regulator of filopodia formation. Accordingly, NRP1 knockdown and pharmacological CDC42 inhibition similarly impaired filopodia formation in vitro and in developing zebrafish in vivo. During mouse retinal angiogenesis, CDC42 inhibition impaired tip cell and vascular network formation, causing defects that resembled those due to loss of ECM-induced, but not VEGF-induced, NRP1 signaling. We conclude that NRP1 enables ECM-induced filopodia formation for tip cell function during sprouting angiogenesis.

  4. Self-regulation of charged defect compensation and formation energy pinning in semiconductors.

    Science.gov (United States)

    Yang, Ji-Hui; Yin, Wan-Jian; Park, Ji-Sang; Wei, Su-Huai

    2015-01-01

    Current theoretical analyses of defect properties without solving the detailed balance equations often estimate Fermi-level pinning position by omitting free carriers and assume defect concentrations can be always tuned by atomic chemical potentials. This could be misleading in some circumstance. Here we clarify that: (1) Because the Fermi-level pinning is determined not only by defect states but also by free carriers from band-edge states, band-edge states should be treated explicitly in the same footing as the defect states in practice; (2) defect formation energy, thus defect density, could be pinned and independent on atomic chemical potentials due to the entanglement of atomic chemical potentials and Fermi energy, in contrast to the usual expectation that defect formation energy can always be tuned by varying the atomic chemical potentials; and (3) the charged defect compensation behavior, i.e., most of donors are compensated by acceptors or vice versa, is self-regulated when defect formation energies are pinned. The last two phenomena are more dominant in wide-gap semiconductors or when the defect formation energies are small. Using NaCl and CH3NH3PbI3 as examples, we illustrate these unexpected behaviors. Our analysis thus provides new insights that enrich the understanding of the defect physics in semiconductors and insulators. PMID:26584670

  5. Targeting P38 Pathway Regulates Bony Formation via MSC Recruitment during Mandibular Distraction Osteogenesis in Rats

    Science.gov (United States)

    Yang, Zi-hui; Wu, Bao-lei; Ye, Chen; Jia, Sen; Yang, Xin-jie; Hou, Rui; Lei, De-lin; Wang, Lei

    2016-01-01

    Distraction osteogenesis (DO) is a widely used self-tissue engineering. However, complications and discomfort due to the long treatment period are still the bottleneck of DO. Novel strategies to accelerate bone formation in DO are still needed. P38 is capable of regulating the osteogenic differentiation of both mesenchymal stem cells (MSCs) and osteoblasts, which are crucial to bone regeneration. However, it is not clear whether targeting p38 could regulate bony formation in DO. The purpose of the current work was to investigate the effects of local application of either p38 agonist anisomycin or p38 inhibitor SB203580 in a rat model of DO. 30 adult rats were randomly divided into 3 groups: (A) rats injected with DMSO served as the control group; (B) rats injected with p38 agonist anisomycin; (C) rats injected with p38 inhibitor SB203580. All the rats were subjected to mandibular distraction and the injection was performed daily during this period. The distracted mandibles were harvested on days 15 and 30 after surgery and subjected to the following analysis. Micro-computed tomography and histological evaluation results showed that local application of p38 agonist anisomycin increased new bone formation in DO, whereas p38 inhibitor SB203580 decreased it. Immunohistochemical analysis suggested that anisomycin promoted MSC recruitment in the distraction gap. In conclusion, this study demonstrated that local application of p38 agonist anisomycin can increase new bone formation during DO. This study may lead to a novel cell-based strategy for the improvement of bone regeneration. PMID:27766028

  6. Diverse protein regulations on PHA formation in Ralstonia eutropha on short chain organic acids

    Directory of Open Access Journals (Sweden)

    Sung-Eun Lee, Qing X. Li, Jian Yu

    2009-01-01

    Full Text Available Organic acids are considered as potential substrates for biosynthesis of polyhydroxyalkaonates. The acids may also be the metabolic inhibitors at moderate concentration levels. In this study, Ralstonia eutropha was used to elucidate the protein regulations when the bacterial cells pre-cultivated on glucose were exposed to three representative short chain organic acids, acetic, propionic and levulinic acids. The research compared and examined the proteins that might participate in PHA metabolism, primary metabolism, and cell's defense systems. A number of proteins were found to be induced in R. eutropha by using 1D-PAGE and nano-liquid chromatography tandem MS/MS. With the proteins being up-regulated, a dramatic change occurred in the induction of PHA metabolism, including fatty acid biosynthesis for acetate, β-oxidation for propionate and both for levulinic acid. Acetate kinase was induced in response to the presence of acetate or levulinic acid. The organic acids induced several proteins involved in amino acid biosynthesis, purine and pyrimidine biosynthesis, and cofactor biosynthesis in R. eutropha, but the regulations had a great variation. R. eutropha might employ different regulation mechanisms to maintain cell growth and PHA formation when the cells are exposed to the organic acids as sole source of carbon and energy.

  7. Dynamics of ordering in highly degenerate models with anisotropic grain-boundary potential: Effects of temperature and vortex formation

    OpenAIRE

    Jeppesen, Claus; Flyvbjerg, Henrik; Ole G. Mouritsen

    1989-01-01

    Monte Carlo computer-simulation techniques are used to elucidate the equilibrium phase behavior as well as the late-stage ordering dynamics of some two-dimensional models with ground-state ordering of a high degeneracy, Q. The models are Q-state Potts models with anisotropic grain-boundary potential on triangular lattices—essentially clock models, except that the potential is not a cosine, but a sine function of the angle between neighboring grain orientations. For not too small Q, these mode...

  8. Regulation of star formation in giant galaxies by precipitation, feedback and conduction.

    Science.gov (United States)

    Voit, G M; Donahue, M; Bryan, G L; McDonald, M

    2015-03-12

    The Universe's largest galaxies reside at the centres of galaxy clusters and are embedded in hot gas that, if left undisturbed, would cool quickly and create many more new stars than are actually observed. Cooling can be regulated by feedback from accretion of cooling gas onto the central black hole, but requires an accretion rate finely tuned to the thermodynamic state of the hot gas. Theoretical models in which cold clouds precipitate out of the hot gas via thermal instability and accrete onto the black hole exhibit the necessary tuning. Recent observational evidence shows that the abundance of cold gas in the centres of clusters increases rapidly near the predicted threshold for instability. Here we report observations showing that this precipitation threshold extends over a large range in cluster radius, cluster mass and cosmic time. We incorporate the precipitation threshold into a framework of theoretical models for the thermodynamic state of hot gas in galaxy clusters. According to that framework, precipitation regulates star formation in some giant galaxies, while thermal conduction prevents star formation in others if it can compensate for radiative cooling and shut off precipitation. PMID:25739501

  9. Magnetically Regulated Star Formation in Three Dimensions: The Case of the Taurus Molecular Cloud Complex

    Science.gov (United States)

    Nakamura, Fumitaka; Li, Zhi-Yun

    2008-11-01

    We carry out three-dimensional MHD simulations of star formation in turbulent, magnetized clouds, including ambipolar diffusion and feedback from protostellar outflows. The calculations focus on relatively diffuse clouds threaded by a strong magnetic field capable of resisting severe tangling by turbulent motions and retarding global gravitational contraction in the cross field direction. They are motivated by observations of the Taurus molecular cloud complex (and, to a lesser extent, Pipe Nebula), which shows an ordered large-scale magnetic field, as well as elongated condensations that are generally perpendicular to the large-scale field. We find that stars form in earnest in such clouds when enough material has settled gravitationally along the field lines that the mass-to-flux ratios of the condensations approach the critical value. Only a small fraction (of order 1% or less) of the nearly magnetically critical, condensed material is turned into stars per local free-fall time, however. The slow star formation takes place in condensations that are moderately supersonic; it is regulated primarily by magnetic fields, rather than turbulence. The quiescent condensations are surrounded by diffuse halos that are much more turbulent, as observed in the Taurus complex. Strong support for magnetic regulation of star formation in this complex comes from the extremely slow conversion of the already condensed, relatively quiescent C18O gas into stars, at a rate 2 orders of magnitude below the maximum, free-fall value. We analyze the properties of dense cores, including their mass spectrum, which resembles the stellar initial mass function.

  10. Prostaglandin E2 regulates melanocyte dendrite formation through activation of PKCζ

    International Nuclear Information System (INIS)

    Prostaglandins are lipid signaling intermediates released by keratinocytes in response to ultraviolet irradiation (UVR) in the skin. The main prostaglandin released following UVR is PGE2, a ligand for 4 related G-protein-coupled receptors (EP1, EP2, EP3 and EP4). Our previous work established that PGE2 stimulates melanocyte dendrite formation through activation of the EP1 and EP3 receptors. The purpose of the present report is to define the signaling intermediates involved in EP1- and EP3-dependent dendrite formation in human melanocytes. We recently showed that activation of the atypical PKCζ isoform stimulates melanocyte dendricity in response to treatment with lysophosphatidylcholine. We therefore examined the potential contribution of PKCζ activation on EP1- and EP3-dependent dendrite formation in melanocytes. Stimulation of the EP1 and EP3 receptors by selective agonists activated PKCζ, and inhibition of PKCζ activation abrogated EP1- and EP3-receptor-mediated melanocyte dendricity. Because of the importance of Rho-GTP binding proteins in the regulation of melanocyte dendricity, we also examined the effect of EP1 and EP3 receptor activation on Rac and Rho activity. Neither Rac nor Rho was activated upon treatment with EP1,3-receptor agonists. We show that melanocytes express only the EP3A1 isoform, but not the EP3B receptor isoform, previously associated with Rho activation, consistent with a lack of Rho stimulation by EP3 agonists. Our data suggest that PKCζ activation plays a predominant role in regulation of PGE2-dependent melanocyte dendricity

  11. Formation of Graphene Grain Boundaries on Cu(100) Surface and a Route Towards Their Elimination in Chemical Vapor Deposition Growth

    Science.gov (United States)

    Yuan, Qinghong; Song, Guangyao; Sun, Deyan; Ding, Feng

    2014-10-01

    Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface -- Cu(100) surface, is explored by density functional theory (DFT) calculations. Our calculation demonstrates that a zigzag edged hexagonal graphene domain on a Cu(100) surface has two equivalent energetically preferred orientations, which are 30 degree away from each other. Therefore, the fusion of graphene domains on Cu(100) surface during CVD growth will inevitably lead to densely distributed GBs in the synthesized graphene. Aiming to solve this problem, a simple route, that applies external strain to break the symmetry of the Cu(100) surface, was proposed and proved efficient.

  12. Formation of graphene grain boundaries on Cu(100) surface and a route towards their elimination in chemical vapor deposition growth.

    Science.gov (United States)

    Yuan, Qinghong; Song, Guangyao; Sun, Deyan; Ding, Feng

    2014-01-01

    Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface - Cu(100) surface, is explored by density functional theory (DFT) calculations. Our calculation demonstrates that a zigzag edged hexagonal graphene domain on a Cu(100) surface has two equivalent energetically preferred orientations, which are 30 degree away from each other. Therefore, the fusion of graphene domains on Cu(100) surface during CVD growth will inevitably lead to densely distributed GBs in the synthesized graphene. Aiming to solve this problem, a simple route, that applies external strain to break the symmetry of the Cu(100) surface, was proposed and proved efficient. PMID:25286970

  13. AMP-activated protein kinase (AMPK) activation regulates in vitro bone formation and bone mass.

    Science.gov (United States)

    Shah, M; Kola, B; Bataveljic, A; Arnett, T R; Viollet, B; Saxon, L; Korbonits, M; Chenu, C

    2010-08-01

    Adenosine 5'-monophosphate-activated protein kinase (AMPK), a regulator of energy homeostasis, has a central role in mediating the appetite-modulating and metabolic effects of many hormones and antidiabetic drugs metformin and glitazones. The objective of this study was to determine if AMPK can be activated in osteoblasts by known AMPK modulators and if AMPK activity is involved in osteoblast function in vitro and regulation of bone mass in vivo. ROS 17/2.8 rat osteoblast-like cells were cultured in the presence of AMPK activators (AICAR and metformin), AMPK inhibitor (compound C), the gastric peptide hormone ghrelin and the beta-adrenergic blocker propranolol. AMPK activity was measured in cell lysates by a functional kinase assay and AMPK protein phosphorylation was studied by Western Blotting using an antibody recognizing AMPK Thr-172 residue. We demonstrated that treatment of ROS 17/2.8 cells with AICAR and metformin stimulates Thr-172 phosphorylation of AMPK and dose-dependently increases its activity. In contrast, treatment of ROS 17/2.8 cells with compound C inhibited AMPK phosphorylation. Ghrelin and propranolol dose-dependently increased AMPK phosphorylation and activity. Cell proliferation and alkaline phosphatase activity were not affected by metformin treatment while AICAR significantly inhibited ROS 17/2.8 cell proliferation and alkaline phosphatase activity at high concentrations. To study the effect of AMPK activation on bone formation in vitro, primary osteoblasts obtained from rat calvaria were cultured for 14-17days in the presence of AICAR, metformin and compound C. Formation of 'trabecular-shaped' bone nodules was evaluated following alizarin red staining. We demonstrated that both AICAR and metformin dose-dependently increase trabecular bone nodule formation, while compound C inhibits bone formation. When primary osteoblasts were co-treated with AICAR and compound C, compound C suppressed the stimulatory effect of AICAR on bone nodule formation

  14. The geological significance of the boundary between the Fort Sill and Signal Mountain Formations in the lower Arbuckle Group (Cambrian)

    Energy Technology Data Exchange (ETDEWEB)

    Hosey, R.; Donovan, R.N. (Texas Christian Univ., Ft Worth, TX (United States). Geology Dept.)

    1993-02-01

    During the upper Cambrian, a transgression inundated the Southern Oklahoma aulacogen enveloping a landscape that consisted of hills of Cambrian-aged rhyolite up to 350 m in height. Initial deposits on this topography--the Reagan Formation--consist of siliciclastics that were deposited as alluvium and succeeding tidally-influenced marine sandstones and shales. The siliciclastics grains are made up of local rhyolite, quartz and authigenic glauconite. The overlying Honeycreek Formation is defined by the addition of carbonated detritus in the form of tidally-influenced pelmatozoan grainstones. The passage from the Honeycreek to the overlying Fort Sill Formation of the Arbuckle Group is marked by the incoming of beds of lime mudstone and the gradual disappearance of grainstones and siliciclastics. The contact between the Fort Sill and the overlying thinly-bedded dark grey bioclastic limestones of the Signal Mountain Formation is one of the most distinctive horizons in the Arbuckle Group. The contact evidently marks a substantial change in depositional environment. In detail the contact is sharp and shows evidence of minor erosion, although no karsting has been detected. The authors suggest that the contact surface records a regression, perhaps associated with dolomitization and followed by some erosion. A regression is also indicated by the local occurrence of a laminated tidal flat unit with traces of evaporites that outcrops in the far west of the Slick Hills immediately below the formation contact. They suggest that the Signal Mountains as a transgressive unit, incorporating siliciclastics transported into the area during the regression. It has been suggested that the unconformity reflects localized tectonism associated with the evolution of the Southern Oklahoma aulacogen. On the other hand the surface may correlate with a craton--wide Sauxian' hiatus.

  15. Transcriptional, post-transcriptional and post-translational regulations of gene expression during leaf polarity formation

    Institute of Scientific and Technical Information of China (English)

    Lin Xu; Li Yang; Hai Huang

    2007-01-01

    Leaf morphogenesis requires the establishment of adaxial-abaxial polarity after primordium initiation from the shoot apical meristem (SAM). Several families of transcription factors are known to play critical roles in promoting adaxial or abaxial leaf fate. Recently, post-transcriptional gene silencing pathways have been shown to regulate the establishment of leaf polarity, providing novel and exciting insights into leaf development. For example, microRNAs (miR165/166)and a trans-acting siRNA (TAS3-derived tasiR-ARF) have been shown to repress the expression of several key transcription factor genes. In addition, yet another level of regulation, post-translational regulation, has been revealed recently by studies on the role of the 26S proteasome in leaf polarity. Although our understanding regarding the molecular mechanisms underlying establishment of adaxial-abaxial polarity has greatly improved, there is still much that remains elusive.This review aims to discuss recent progress, as well as the remaining questions, regarding the molecular mechanisms underlying leaf polarity formation.

  16. Effects of local pH on the formation and regulation of cristae morphologies

    Science.gov (United States)

    Song, Dong Hoon; Park, Jonghyun; Philbert, Martin A.; Sastry, Ann Marie; Lu, Wei

    2014-08-01

    Cristae, folded subcompartments of the inner mitochondrial membrane (IMM), have complex and dynamic morphologies. Since cristae are the major site of adenosine triphosphate synthesis, morphological changes of cristae have been studied in relation to functional states of mitochondria. In this sense, investigating the functional and structural significance of cristae may be critical for understanding progressive mitochondrial dysfunction. However, the detailed mechanisms of the formation and regulation of these cristae structures have not been fully elucidated. Among the hypotheses concerning the regulation of cristae morphologies, we exclusively investigate the effects of the local pH gradient on the cristae morphologies by using a numerical model. An area-difference induced curvature of the membrane is modeled as a function of local pH. This curvature is then applied to the finite element model of a closed lipid bilayer in order to find the energetically favorable membrane configuration. From this study, we substantiate the hypothesis that a tubular crista structure can be formed and regulated by the local pH gradient. Through the simulations with various initial conditions, we further demonstrate that the diameter of a crista is mainly determined by the local pH gradient, and the energetically favorable direction of crista growth is perpendicular to the longitudinal axis of a mitochondrion. Finally, the simulation results at the mitochondrial scale suggest that the cristae membrane may have a lower local pH value and/or a higher cardiolipin composition than the other parts of the IMM.

  17. Becoming popular: Interpersonal emotion regulation predicts relationship formation in real life social networks

    Directory of Open Access Journals (Sweden)

    Karen eNiven

    2015-09-01

    Full Text Available Building relationships is crucial for satisfaction and success, especially when entering new social contexts. In the present paper, we investigate whether attempting to improve others’ feelings helps people to make connections in new networks. In Study 1, a social network study following new networks of people for a twelve-week period indicated that use of interpersonal emotion regulation (IER strategies predicted growth in popularity, as indicated by other network members’ reports of spending time with the person, in work and non-work interactions. In Study 2, linguistic analysis of the tweets from over 8000 Twitter users from formation of their accounts revealed that use of IER predicted greater popularity in terms of the number of followers gained. However, not all types of IER had positive effects. Behavioral IER strategies (which use behavior to reassure or comfort in order to regulate affect were associated with greater popularity, while cognitive strategies (which change a person’s thoughts about his or her situation or feelings in order to regulate affect were negatively associated with popularity. Our findings have implications for our understanding of how new relationships are formed, highlighting the important the role played by intentional emotion regulatory processes.

  18. THE FORMATION OF ENTS ADAPTIVE REACTIONS DEPENDING ON THE TYPE OF PSYCHO-VEGETATIVE REGULATION

    Directory of Open Access Journals (Sweden)

    E. M. Kazin

    2014-01-01

    Full Text Available The purpose of the students (12 to 15 years old examination was to identify the integrative criteria of assessing the nature of the functional relationships between the parameters of the psychosocial and physiological adaptation of students, depending on age, individual-typological peculiarities of vegetative regulation, personal potential at different stages of school education.The study of the characteristics of vegetative regulation of the cardiovascular system was made with a help of an automatic cardiac-rhythm programs. The research of psychophysiological parameters was fulfiled using an automatic complex. The measurement of the speed of simple visual-motor reaction (PSMR, reaction to a moving object (WFD, the level of functional mobility of nervous processes (WFP and health brain (DDM were made before. Features psychosocial adaptation was analyzed using 8-color Luscher test.All examinee were divided into three groups on the basis of the statistical characteristics of the cardiac rhythm by the tone source autonomic tone: “vagotonia” (with a predominance of parasympathetic sistems, “somatotonic” (with domination of the sympatholytic effects, “atonic” (balanced type of vegetative nervous system.Based on the analysis of psychodynamic, neurodynamic and vegetative functions showed that students with initial vagotonies tone are characterized by high levels of situational and personal anxiety, low psychosocial adaptation, decreased activity of neurodynamic functions and psychodynamic processes in the learning dynamics, whereas the individuals with dominance of sympatotonics type regulation have high level of neurodynamic processes, psychosocial adaptation, against the background of significant stress mechanisms of vegetative regulation.Students with initial vegetative tone demonstrate a sufficient level of psychosocial adaptation, activity psychodynamic and neuromotor processes, accompanied by the preservation of the functionality of

  19. Isotopic constraints on the role of hypohalous acids in sulfate aerosol formation in the remote marine boundary layer

    Science.gov (United States)

    Chen, Qianjie; Geng, Lei; Schmidt, Johan A.; Xie, Zhouqing; Kang, Hui; Dachs, Jordi; Cole-Dai, Jihong; Schauer, Andrew J.; Camp, Madeline G.; Alexander, Becky

    2016-09-01

    Sulfate is an important component of global atmospheric aerosol, and has partially compensated for greenhouse gas-induced warming during the industrial period. The magnitude of direct and indirect radiative forcing of aerosols since preindustrial times is a large uncertainty in climate models, which has been attributed largely to uncertainties in the preindustrial environment. Here, we report observations of the oxygen isotopic composition (Δ17O) of sulfate aerosol collected in the remote marine boundary layer (MBL) in spring and summer in order to evaluate sulfate production mechanisms in pristine-like environments. Model-aided analysis of the observations suggests that 33-50 % of sulfate in the MBL is formed via oxidation by hypohalous acids (HOX = HOBr + HOCl), a production mechanism typically excluded in large-scale models due to uncertainties in the reaction rates, which are due mainly to uncertainties in reactive halogen concentrations. Based on the estimated fraction of sulfate formed via HOX oxidation, we further estimate that daily-averaged HOX mixing ratios on the order of 0.01-0.1 parts per trillion (ppt = pmol/mol) in the remote MBL during spring and summer are sufficient to explain the observations.

  20. Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe Roscoff coastal study

    Directory of Open Access Journals (Sweden)

    G. McFiggans

    2010-03-01

    Full Text Available This paper presents a summary of the measurements made during the heavily-instrumented Reactive Halogens in the Marine Boundary Layer (RHaMBLe coastal study in Roscoff on the North West coast of France throughout September 2006. It was clearly demonstrated that iodine-mediated coastal particle formation occurs, driven by daytime low tide emission of molecular iodine, I2, by macroalgal species fully or partially exposed by the receding waterline. Ultrafine particle concentrations strongly correlate with the rapidly recycled reactive iodine species, IO, produced at high concentrations following photolysis of I2. The heterogeneous macroalgal I2 sources lead to variable relative concentrations of iodine species observed by path-integrated and in situ measurement techniques.

    Apparent particle emission fluxes were associated with an enhanced apparent depositional flux of ozone, consistent with both a direct O3 deposition to macroalgae and involvement of O3 in iodine photochemistry and subsequent particle formation below the measurement height. The magnitude of the particle formation events was observed to be greatest at the lowest tides with the highest concentrations of ultrafine particles growing to the largest sizes, probably by the condensation of anthropogenically-formed condensable material. At such sizes the particles should be able to act as cloud condensation nuclei at reasonable atmospheric supersaturations.

  1. Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe Roscoff coastal study

    Directory of Open Access Journals (Sweden)

    G. McFiggans

    2009-12-01

    Full Text Available This paper presents a summary of the measurements that were made during the heavily-instrumented Reactive Halogens in the Marine Boundary Layer (RHaMBLe coastal study in Roscoff on the North West coast of France. It was clearly demonstrated that iodine-mediated coastal particle formation occurs, driven by daytime low tide emission of molecular iodine, I2, by macroalgal species fully or partially exposed by the receding waterline. Ultrafine particle concentrations strongly correlate with the rapidly recycled reactive iodine species, IO, produced at high concentrations following photolysis of I2. The heterogeneous macroalgal I2 sources lead to variable relative concentrations of iodine species observed by path-integrated and in situ measurement techniques.

    Apparent particle emission fluxes were associated with an enhanced apparent depositional flux of ozone, consistent with both a direct O3 deposition to macroalgae and involvement of O3 in iodine photochemistry and subsequent particle formation below the measurement height. The magnitude of the particle formation events was observed to be greatest at the lowest tides with higher concentrations of ultrafine particles growing to much larger sizes, probably by the condensation of anthropogenically-formed condensable material. At such sizes the particles should be able to act as cloud condensation nuclei at reasonable atmospheric supersaturations.

  2. Ras-Mek-Erk signaling regulates Nf1 heterozygous neointima formation.

    Science.gov (United States)

    Stansfield, Brian K; Bessler, Waylan K; Mali, Raghuveer; Mund, Julie A; Downing, Brandon D; Kapur, Reuben; Ingram, David A

    2014-01-01

    Neurofibromatosis type 1 (NF1) results from mutations in the NF1 tumor-suppressor gene, which encodes neurofibromin, a negative regulator of diverse Ras signaling cascades. Arterial stenosis is a nonneoplastic manifestation of NF1 that predisposes some patients to debilitating morbidity and sudden death. Recent murine studies demonstrate that Nf1 heterozygosity (Nf1(+/-)) in monocytes/macrophages significantly enhances intimal proliferation after arterial injury. However, the downstream Ras effector pathway responsible for this phenotype is unknown. Based on in vitro assays demonstrating enhanced extracellular signal-related kinase (Erk) signaling in Nf1(+/-) macrophages and vascular smooth muscle cells and in vivo evidence of Erk amplification without alteration of phosphatidylinositol 3-kinase signaling in Nf1(+/-) neointimas, we tested the hypothesis that Ras-Erk signaling regulates intimal proliferation in a murine model of NF1 arterial stenosis. By using a well-established in vivo model of inflammatory cell migration and standard cell culture, neurofibromin-deficient macrophages demonstrate enhanced sensitivity to growth factor stimulation in vivo and in vitro, which is significantly diminished in the presence of PD0325901, a specific inhibitor of Ras-Erk signaling in phase 2 clinical trials for cancer. After carotid artery injury, Nf1(+/-) mice demonstrated increased intimal proliferation compared with wild-type mice. Daily administration of PD0325901 significantly reduced Nf1(+/-) neointima formation to levels of wild-type mice. These studies identify the Ras-Erk pathway in neurofibromin-deficient macrophages as the aberrant pathway responsible for enhanced neointima formation. PMID:24211110

  3. Response regulator heterodimer formation controls a key stage in Streptomyces development.

    Directory of Open Access Journals (Sweden)

    Mahmoud M Al-Bassam

    2014-08-01

    Full Text Available The orphan, atypical response regulators BldM and WhiI each play critical roles in Streptomyces differentiation. BldM is required for the formation of aerial hyphae, and WhiI is required for the differentiation of these reproductive structures into mature spores. To gain insight into BldM function, we defined the genome-wide BldM regulon using ChIP-Seq and transcriptional profiling. BldM target genes clustered into two groups based on their whi gene dependency. Expression of Group I genes depended on bldM but was independent of all the whi genes, and biochemical experiments showed that Group I promoters were controlled by a BldM homodimer. In contrast, Group II genes were expressed later than Group I genes and their expression depended not only on bldM but also on whiI and whiG (encoding the sigma factor that activates whiI. Additional ChIP-Seq analysis showed that BldM Group II genes were also direct targets of WhiI and that in vivo binding of WhiI to these promoters depended on BldM and vice versa. We go on to demonstrate that BldM and WhiI form a functional heterodimer that controls Group II promoters, serving to integrate signals from two distinct developmental pathways. The BldM-WhiI system thus exemplifies the potential of response regulator heterodimer formation as a mechanism to expand the signaling capabilities of bacterial cells.

  4. Transcriptional profiling reveals regulated genes in the hippocampus during memory formation

    Science.gov (United States)

    Donahue, Christine P.; Jensen, Roderick V.; Ochiishi, Tomoyo; Eisenstein, Ingrid; Zhao, Mingrui; Shors, Tracey; Kosik, Kenneth S.

    2002-01-01

    Transcriptional profiling (TP) offers a powerful approach to identify genes activated during memory formation and, by inference, the molecular pathways involved. Trace eyeblink conditioning is well suited for the study of regional gene expression because it requires the hippocampus, whereas the highly parallel task, delay conditioning, does not. First, we determined when gene expression was most regulated during trace conditioning. Rats were exposed to 200 trials per day of paired and unpaired stimuli each day for 4 days. Changes in gene expression were most apparent 24 h after exposure to 200 trials. Therefore, we profiled gene expression in the hippocampus 24 h after 200 trials of trace eyeblink conditioning, on multiple arrays using additional animals. Of 1,186 genes on the filter array, seven genes met the statistical criteria and were also validated by real-time polymerase chain reaction. These genes were growth hormone (GH), c-kit receptor tyrosine kinase (c-kit), glutamate receptor, metabotropic 5 (mGluR5), nerve growth factor-beta (NGF-beta), Jun oncogene (c-Jun), transmembrane receptor Unc5H1 (UNC5H1), and transmembrane receptor Unc5H2 (UNC5H2). All these genes, except for GH, were downregulated in response to trace conditioning. GH was upregulated; therefore, we also validated the downregulation of the GH inhibitor, somatostatin (SST), even though it just failed to meet criteria on the arrays. By during situ hybridization, GH was expressed throughout the cell layers of the hippocampus in response to trace conditioning. None of the genes regulated in trace eyeblink conditioning were similarly affected by delay conditioning, a task that does not require the hippocampus. These findings demonstrate that transcriptional profiling can exhibit a repertoire of genes sensitive to the formation of hippocampal-dependent associative memories.

  5. Tissue growth controlled by geometric boundary conditions: a simple model recapitulating aspects of callus formation and bone healing.

    Science.gov (United States)

    Fischer, F Dieter; Zickler, Gerald A; Dunlop, John W C; Fratzl, Peter

    2015-06-01

    The shape of tissues arises from a subtle interplay between biochemical driving forces, leading to cell growth, division and extracellular matrix formation, and the physical constraints of the surrounding environment, giving rise to mechanical signals for the cells. Despite the inherent complexity of such systems, much can still be learnt by treating tissues that constantly remodel as simple fluids. In this approach, remodelling relaxes all internal stresses except for the pressure which is counterbalanced by the surface stress. Our model is used to investigate how wettable substrates influence the stability of tissue nodules. It turns out for a growing tissue nodule in free space, the model predicts only two states: either the tissue shrinks and disappears, or it keeps growing indefinitely. However, as soon as the tissue wets a substrate, stable equilibrium configurations become possible. Furthermore, by investigating more complex substrate geometries, such as tissue growing at the end of a hollow cylinder, we see features reminiscent of healing processes in long bones, such as the existence of a critical gap size above which healing does not occur. Despite its simplicity, the model may be useful in describing various aspects related to tissue growth, including biofilm formation and cancer metastases. PMID:26018964

  6. An investigation of the formation and propagation of horseshoe vortices in a strut-boundary layer interaction, and their effect on inlet distortion

    Science.gov (United States)

    Conway, Matthew J.

    The formation and propagation of a horseshoe vortex system forming as a result of strut-boundary layer interaction is studied to determine its effect on stagnation pressure distortion in an axisymmetric supersonic inlet geometry. The effects of strut leading edge radius, pressure gradients, and curvature of the inlet walls on the vortex system are studied parametrically by performing a CFD simulation of strut-boundary layer interaction in a simplified duct geometry with flow conditions representative of the subsonic diffuser of a supersonic inlet. Leading edge fairings are studied to determine what parameters are most important for the control of the horseshoe vortex system and the reduction of stagnation pressure distortion at the fan. A fairing is designed for struts an axisymmetric, supersonic, mixed-compression inlet which reduces circumferential distortion intensity by 48% at cruise condition with 3 degrees angle of attack. Solutions are obtained to the steady state Reynolds averaged Navier-Stokes equations using WIND, a finite-difference solver developed by NASA Glenn and the USAF Arnold Engineering Development Center. The Spalart-Allmaras one equation turbulence model is used to model eddy viscosity.

  7. Location, formation and biosynthetic regulation of cellulases in the gliding bacteria Cytophaga hutchinsonii

    Directory of Open Access Journals (Sweden)

    Elijah Johnson

    2006-01-01

    Full Text Available An analysis of the recently published genome sequence of Cytophagahutchinsonii revealed an unusual collection of genes for an organism that can attackcrystalline cellulose. Consequently, questions were being raised by cellulase scientists, as towhat mechanism this organism uses to degrade its insoluble substrates. Cellulose, being ahighly polymeric compound and insoluble in water, cannot enter the cell walls ofmicroorganisms. Cellulose-degrading enzymes have therefore to be located on the surface ofthe cell wall or released extracellularly. The location of most cellulase enzymes has beenstudied. However, basic information on C. hutchinsonii cellulases is almost non-existent. Inthe present study, the location, formation and biosynthetic regulation of cellulases in C.hutchinsonii were demonstrated on different substrates. Various fractions isolated from C.hutchinsonii after cell rupture were assayed for carboxymethyl-cellulase activity (CMC.The cellulases were found to be predominantly cell-free during active growth on solka-flok,although 30% of activity was recorded on cell-bound enzymes. Relatively little CM-cellulase was formed when cells were grown on glucose and cellobiose. Apparently glucoseor labile substrates such as cellobiose seem to repress the formation of CM-cellulase. Thesefindings should provide some insight into possible hydrolysis mechanisms by C.hutchinsonii.

  8. A TNF-regulated recombinatorial macrophage immune receptor implicated in granuloma formation in tuberculosis.

    Directory of Open Access Journals (Sweden)

    Alexander W Beham

    2011-11-01

    Full Text Available Macrophages play a central role in host defense against mycobacterial infection and anti- TNF therapy is associated with granuloma disorganization and reactivation of tuberculosis in humans. Here, we provide evidence for the presence of a T cell receptor (TCR αβ based recombinatorial immune receptor in subpopulations of human and mouse monocytes and macrophages. In vitro, we find that the macrophage-TCRαβ induces the release of CCL2 and modulates phagocytosis. TNF blockade suppresses macrophage-TCRαβ expression. Infection of macrophages from healthy individuals with mycobacteria triggers formation of clusters that express restricted TCR Vβ repertoires. In vivo, TCRαβ bearing macrophages abundantly accumulate at the inner host-pathogen contact zone of caseous granulomas from patients with lung tuberculosis. In chimeric mouse models, deletion of the variable macrophage-TCRαβ or TNF is associated with structurally compromised granulomas of pulmonary tuberculosis even in the presence of intact T cells. These results uncover a TNF-regulated recombinatorial immune receptor in monocytes/macrophages and demonstrate its implication in granuloma formation in tuberculosis.

  9. Inhibition of quorum sensing regulated biofilm formation in Serratia marcescens causing nosocomial infections.

    Science.gov (United States)

    Bakkiyaraj, Dhamodharan; Sivasankar, Chandran; Pandian, Shunmugiah Karutha

    2012-05-01

    Serratia marcescens is an opportunistic pathogen causing severe urinary tract infections in hospitalized individuals. Infections of S. marcescens are of great concern because of its increasing resistance towards conventional antibiotics. Quorum sensing (QS)-a cell to cell communication-system of S. marcescens acts as a global regulator of almost all the virulence factors and majorly its biofilm formation. Since, the QS system of S. marcescens directly accords to its pathogenesis, targeting QS system will provide an improved strategy to combat drug resistant pathogens. In the present study, QS system of S. marcescens has been used as target and its inhibition has been studied upon exposure to bioactives from coral associated bacteria (CAB). This study also emphasises the potential of CAB in producing bioactive agents with anti-QS and antibiofilm properties. Two CAB isolates CAB 23 and 41 have shown to inhibit biofilm formation and the production of QS dependent virulence factors like prodigiosin, protease, lipase and swarming motility. The study, on the whole explicates the potential of QS system as a target to treat drug resistant bacterial infections. PMID:22487181

  10. A keratin scaffold regulates epidermal barrier formation, mitochondrial lipid composition, and activity

    Science.gov (United States)

    Kumar, Vinod; Bouameur, Jamal-Eddine; Bär, Janina; Rice, Robert H.; Hornig-Do, Hue-Tran; Roop, Dennis R.; Schwarz, Nicole; Brodesser, Susanne; Thiering, Sören; Leube, Rudolf E.; Wiesner, Rudolf J.; Vijayaraj, Preethi; Brazel, Christina B.; Heller, Sandra; Binder, Hans; Löffler-Wirth, Henry; Seibel, Peter

    2015-01-01

    Keratin intermediate filaments (KIFs) protect the epidermis against mechanical force, support strong adhesion, help barrier formation, and regulate growth. The mechanisms by which type I and II keratins contribute to these functions remain incompletely understood. Here, we report that mice lacking all type I or type II keratins display severe barrier defects and fragile skin, leading to perinatal mortality with full penetrance. Comparative proteomics of cornified envelopes (CEs) from prenatal KtyI−/− and KtyII−/−K8 mice demonstrates that absence of KIF causes dysregulation of many CE constituents, including downregulation of desmoglein 1. Despite persistence of loricrin expression and upregulation of many Nrf2 targets, including CE components Sprr2d and Sprr2h, extensive barrier defects persist, identifying keratins as essential CE scaffolds. Furthermore, we show that KIFs control mitochondrial lipid composition and activity in a cell-intrinsic manner. Therefore, our study explains the complexity of keratinopathies accompanied by barrier disorders by linking keratin scaffolds to mitochondria, adhesion, and CE formation. PMID:26644517

  11. DNA Methylation Dynamics Regulate the Formation of a Regenerative Wound Epithelium during Axolotl Limb Regeneration.

    Science.gov (United States)

    Aguilar, Cristian; Gardiner, David M

    2015-01-01

    The formation of a blastema during regeneration of an axolotl limb involves important changes in the behavior and function of cells at the site of injury. One of the earliest events is the formation of the wound epithelium and subsequently the apical epidermal cap, which involves in vivo dedifferentiation that is controlled by signaling from the nerve. We have investigated the role of epigenetic modifications to the genome as a possible mechanism for regulating changes in gene expression patterns of keratinocytes of the wound and blastema epithelium that are involved in regeneration. We report a modulation of the expression DNMT3a, a de novo DNA methyltransferase, within the first 72 hours post injury that is dependent on nerve signaling. Treatment of skin wounds on the upper forelimb with decitabine, a DNA methyltransferase inhibitor, induced changes in gene expression and cellular behavior associated with a regenerative response. Furthermore, decitabine-treated wounds were able to participate in regeneration while untreated wounds inhibited a regenerative response. Elucidation of the specific epigenetic modifications that mediate cellular dedifferentiation likely will lead to insights for initiating a regenerative response in organisms that lack this ability.

  12. Feedback Regulated Turbulence, Magnetic Fields, and Star Formation Rates in Galactic Disks

    CERN Document Server

    Kim, Chang-Goo

    2015-01-01

    We use three-dimensional magnetohydrodynamic (MHD) simulations to investigate the quasi-equilibrium states of galactic disks regulated by star formation feedback. We incorporate effects from massive-star feedback via time-varying heating rates and supernova (SN) explosions. We find that the disks in our simulations rapidly approach a quasi-steady state that satisfies vertical dynamical equilibrium. The star formation rate (SFR) surface density self-adjusts to provide the total momentum flux (pressure) in the vertical direction that matches the weight of the gas. We quantify feedback efficiency by measuring feedback yields, \\eta_c\\equiv P_c/\\Sigma_SFR (in suitable units), for each pressure component. The turbulent and thermal feedback yields are the same for HD and MHD simulations, \\eta_th~1 and \\eta_ turb~4, consistent with the theoretical expectations. In MHD simulations, turbulent magnetic fields are rapidly generated by turbulence, and saturate at a level corresponding to \\eta_mag,t~1. The presence of magn...

  13. DNA Methylation Dynamics Regulate the Formation of a Regenerative Wound Epithelium during Axolotl Limb Regeneration.

    Directory of Open Access Journals (Sweden)

    Cristian Aguilar

    Full Text Available The formation of a blastema during regeneration of an axolotl limb involves important changes in the behavior and function of cells at the site of injury. One of the earliest events is the formation of the wound epithelium and subsequently the apical epidermal cap, which involves in vivo dedifferentiation that is controlled by signaling from the nerve. We have investigated the role of epigenetic modifications to the genome as a possible mechanism for regulating changes in gene expression patterns of keratinocytes of the wound and blastema epithelium that are involved in regeneration. We report a modulation of the expression DNMT3a, a de novo DNA methyltransferase, within the first 72 hours post injury that is dependent on nerve signaling. Treatment of skin wounds on the upper forelimb with decitabine, a DNA methyltransferase inhibitor, induced changes in gene expression and cellular behavior associated with a regenerative response. Furthermore, decitabine-treated wounds were able to participate in regeneration while untreated wounds inhibited a regenerative response. Elucidation of the specific epigenetic modifications that mediate cellular dedifferentiation likely will lead to insights for initiating a regenerative response in organisms that lack this ability.

  14. Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine mediated particle formation in the marine boundary layer

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2012-09-01

    Full Text Available Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. These ultra-fine particles may then grow through the condensation of other materials to sizes where they may serve as cloud condensation nuclei. There has been some debate over the chemical identity of the initially nucleated particles. In laboratory simulations, hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5·H2O. In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH. On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass. Water retention in amorphous material at low RH is important for understanding the hygroscopic growth of aerosol particles and uptake of other condensable material. Subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only 6%, which is remarkably small for a highly soluble material. We suggest that the

  15. [Regulation of neurogenesis: factors affecting of new neurons formation in adult mammals brain].

    Science.gov (United States)

    Respondek, Michalina; Buszman, Ewa

    2015-12-31

    Neurogenesis is a complex and multi-step process of generating completely functional neurons. This process in adult brain is based on pluripotentional neuronal stem cells (NSC), which are able to proliferation and differentiation into mature neurons or glial cells. NSC are located in subgranular zone inside hippocampus and in subventricular zone. The new neurons formation depends on many endo- and exogenous factors which modulate each step of neurogenesis. This article describes the most important regulators of adult neurogenesis, mainly: neurotrophins, growth factors, hormones, neurotransmitters and microenvironment of NSC. Some drugs, especially antipsychotics, antidepressants and normothymics may affect the neurogenic properties of adult brain. Moreover pathological processes such as neuroinflammation, stroke or epilepsy are able to induce proliferation of NSC. The proneurogenic effects of psychotropic drugs and pathological processes are associated with their ability to increase some hormones and neurotrophins level, as well as with rising the expression of antiapoptotic Bcl-2 protein and metalloproteinase MMP-2. Additionaly, some drugs, for example haloperidol, are able to block prolactin and dopaminergic neuroblasts receptors. Down-regulation of adult neurogenesis is associated with alcohol abuse and high stress level. Negative effect of many drugs, such as cytostatics, COX-2 inhibitors and opioides was also observed. The proneurogenic effect of described factors suggest their broad therapeutic potential and gives a new perspective on an effective and modern treatment of many neuropsychiatric disorders. This effect can also help to clarify the pathogenesis of disorders associated with proliferation and degeneration of adult brain cells.

  16. Regulation of ice stream flow through subglacial formation of gas hydrates

    Science.gov (United States)

    Winsborrow, Monica; Andreassen, Karin; Hubbard, Alun; Plaza-Faverola, Andreia; Gudlaugsson, Eythor; Patton, Henry

    2016-05-01

    Variations in the flow of ice streams and outlet glaciers are a primary control on ice sheet stability, yet comprehensive understanding of the key processes operating at the ice-bed interface remains elusive. Basal resistance is critical, especially sticky spots--localized zones of high basal traction--for maintaining force balance in an otherwise well-lubricated/high-slip subglacial environment. Here we consider the influence of subglacial gas-hydrate formation on ice stream dynamics, and its potential to initiate and maintain sticky spots. Geophysical data document the geologic footprint of a major palaeo-ice-stream that drained the Barents Sea-Fennoscandian ice sheet approximately 20,000 years ago. Our results reveal a ~250 km2 sticky spot that coincided with subsurface shallow gas accumulations, seafloor fluid expulsion and a fault complex associated with deep hydrocarbon reservoirs. We propose that gas migrating from these reservoirs formed hydrates under high-pressure, low-temperature subglacial conditions. The gas hydrate desiccated, stiffened and thereby strengthened the subglacial sediments, promoting high traction--a sticky spot--that regulated ice stream flow. Deep hydrocarbon reservoirs are common beneath past and contemporary glaciated areas, implying that gas-hydrate regulation of subglacial dynamics could be a widespread phenomenon.

  17. [Regulation of neurogenesis: factors affecting of new neurons formation in adult mammals brain].

    Science.gov (United States)

    Respondek, Michalina; Buszman, Ewa

    2015-01-01

    Neurogenesis is a complex and multi-step process of generating completely functional neurons. This process in adult brain is based on pluripotentional neuronal stem cells (NSC), which are able to proliferation and differentiation into mature neurons or glial cells. NSC are located in subgranular zone inside hippocampus and in subventricular zone. The new neurons formation depends on many endo- and exogenous factors which modulate each step of neurogenesis. This article describes the most important regulators of adult neurogenesis, mainly: neurotrophins, growth factors, hormones, neurotransmitters and microenvironment of NSC. Some drugs, especially antipsychotics, antidepressants and normothymics may affect the neurogenic properties of adult brain. Moreover pathological processes such as neuroinflammation, stroke or epilepsy are able to induce proliferation of NSC. The proneurogenic effects of psychotropic drugs and pathological processes are associated with their ability to increase some hormones and neurotrophins level, as well as with rising the expression of antiapoptotic Bcl-2 protein and metalloproteinase MMP-2. Additionaly, some drugs, for example haloperidol, are able to block prolactin and dopaminergic neuroblasts receptors. Down-regulation of adult neurogenesis is associated with alcohol abuse and high stress level. Negative effect of many drugs, such as cytostatics, COX-2 inhibitors and opioides was also observed. The proneurogenic effect of described factors suggest their broad therapeutic potential and gives a new perspective on an effective and modern treatment of many neuropsychiatric disorders. This effect can also help to clarify the pathogenesis of disorders associated with proliferation and degeneration of adult brain cells. PMID:27259217

  18. Flat leaf formation realized by cell-division control and mutual recessive gene regulation.

    Science.gov (United States)

    Hayakawa, Yoshinori; Tachikawa, Masashi; Mochizuki, Atsushi

    2016-09-01

    Most of the land plants generally have dorsoventrally flat leaves, maximizing the surface area of both upper (adaxial) side and lower (abaxial) side. The former is specialized for light capturing for photosynthesis and the latter is specialized for gas exchange. From findings of molecular genetics, it has been considered that the coupled dynamics between tissue morphogenesis and gene regulation for cell identity is responsible for making flat leaves. The hypothesis claims that a flat leaf is generated under two assumptions, (i) two mutually recessive groups of genes specify adaxial and abaxial sides of a leaf, (ii) cell divisions are induced at the limited region in the leaf margin where both of two groups are expressed. We examined the plausibility and possibility of this hypothesis from the dynamical point of view. We studied a mathematical model where two processes are coupled, tissue morphogenesis induced by cell division and deformation, and dynamics of gene regulations. From the analysis of the model we found that the classically believed hypothesis is not sufficient to generate flat leaves with high probability. We examined several different modifications and revision of the model. Then we found that a simple additional rule of polarized cell division facilitates flat leaf formation. The result of our analysis gives prediction of possible mechanism, which can be easily verified in experiments. PMID:27287339

  19. PPAR-γ activation by Tityus serrulatus venom regulates lipid body formation and lipid mediator production.

    Science.gov (United States)

    Zoccal, Karina Furlani; Paula-Silva, Francisco Wanderley Garcia; Bitencourt, Claudia da Silva; Sorgi, Carlos Artério; Bordon, Karla de Castro Figueiredo; Arantes, Eliane Candiani; Faccioli, Lúcia Helena

    2015-01-01

    Tityus serrulatus venom (TsV) consists of numerous peptides with different physiological and pharmacological activities. Studies have shown that scorpion venom increases pro-inflammatory cytokine production, contributing to immunological imbalance, multiple organ dysfunction, and patient death. We have previously demonstrated that TsV is a venom-associated molecular pattern (VAMP) recognized by TLRs inducing intense inflammatory reaction through the production of pro-inflammatory cytokines and arachidonic acid-derived lipid mediators prostaglandin (PG)E2 and leukotriene (LT)B4. Lipid bodies (LBs) are potential sites for eicosanoid production by inflammatory cells. Moreover, recent studies have shown that the peroxisome proliferator-activated receptor gamma (PPAR-γ) is implicated in LB formation and acts as an important modulator of lipid metabolism during inflammation. In this study, we used murine macrophages to evaluate whether the LB formation induced by TsV after TLR recognition correlates with lipid mediator generation by macrophages and if it occurs through PPAR-γ activation. We demonstrate that TsV acts through TLR2 and TLR4 stimulation and PPAR-γ activation to induce LB formation and generation of PGE2 and LTB4. Our data also show that PPAR-γ negatively regulates the pro-inflammatory NF-κB transcription factor. Based on these results, we suggest that during envenomation, LBs constitute functional organelles for lipid mediator production through signaling pathways that depend on cell surface and nuclear receptors. These findings point to the inflammatory mechanisms that might also be triggered during human envenomation by TsV. PMID:25450800

  20. Pyk2 regulates megakaryocyte-induced increases in osteoblast number and bone formation.

    Science.gov (United States)

    Cheng, Ying-Hua; Hooker, R Adam; Nguyen, Khanh; Gerard-O'Riley, Rita; Waning, David L; Chitteti, Brahmananda R; Meijome, Tomas E; Chua, Hui Lin; Plett, Artur P; Orschell, Christie M; Srour, Edward F; Mayo, Lindsey D; Pavalko, Fredrick M; Bruzzaniti, Angela; Kacena, Melissa A

    2013-06-01

    Preclinical and clinical evidence from megakaryocyte (MK)-related diseases suggests that MKs play a significant role in maintaining bone homeostasis. Findings from our laboratories reveal that MKs significantly increase osteoblast (OB) number through direct MK-OB contact and the activation of integrins. We, therefore, examined the role of Pyk2, a tyrosine kinase known to be regulated downstream of integrins, in the MK-mediated enhancement of OBs. When OBs were co-cultured with MKs, total Pyk2 levels in OBs were significantly enhanced primarily because of increased Pyk2 gene transcription. Additionally, p53 and Mdm2 were both decreased in OBs upon MK stimulation, which would be permissive of cell cycle entry. We then demonstrated that OB number was markedly reduced when Pyk2-/- OBs, as opposed to wild-type (WT) OBs, were co-cultured with MKs. We also determined that MKs inhibit OB differentiation in the presence and absence of Pyk2 expression. Finally, given that MK-replete spleen cells from GATA-1-deficient mice can robustly stimulate OB proliferation and bone formation in WT mice, we adoptively transferred spleen cells from these mice into Pyk2-/- recipient mice. Importantly, GATA-1-deficient spleen cells failed to stimulate an increase in bone formation in Pyk2-/- mice, suggesting in vivo the important role of Pyk2 in the MK-induced increase in bone volume. Further understanding of the signaling pathways involved in the MK-mediated enhancement of OB number and bone formation will facilitate the development of novel anabolic therapies to treat bone loss diseases. PMID:23362087

  1. Wdr18 is required for Kupffer's vesicle formation and regulation of body asymmetry in zebrafish.

    Directory of Open Access Journals (Sweden)

    Wei Gao

    Full Text Available Correct specification of the left-right (L-R axis is important for organ morphogenesis. Conserved mechanisms involving cilia rotation inside node-like structures and asymmetric Nodal signaling in the lateral plate mesoderm (LPM, which are important symmetry-breaking events, have been intensively studied. In zebrafish, the clustering and migration of dorsal forerunner cells (DFCs is critical for the formation of the Kuppfer's vesicle (KV. However, molecular events underlying DFC clustering and migration are less understood. The WD-repeat proteins function in a variety of biological processes, including cytoskeleton assembly, intracellular trafficking, mRNA splicing, transcriptional regulation and cell migration. However, little is known about the function of WD-repeat proteins in L-R asymmetry determination. Here, we report the identification and functional analyses of zebrafish wdr18, a novel gene that encodes a WD-repeat protein that is highly conserved among vertebrate species. wdr18 was identified from a Tol2 transposon-mediated enhancer trap screen. Follow-up analysis of wdr18 mRNA expression showed that it was detected in DFCs or the KV progenitor cells and later in the KV at early somitogenesis stages. Morpholino knockdown of wdr18 resulted in laterality defects in the visceral organs, which were preceded by the mis-expression of Nodal-related genes, including spaw and pitx2. Examination of morphants at earlier stages revealed that the KV had fewer and shorter cilia which are immotile and a smaller cavity. We further investigated the organization of DFCs in wdr18 morphant embryos using ntl and sox17 as specific markers and found that the clustering and migration of DFC was altered, leading to a disorganized KV. Finally, through a combination of wdr18 and itgb1b morpholino injections, we provided evidence that wdr18 and itgb1b genetically interact in the laterality determination process. Thus, we reveal a new and essential role for WD

  2. A novel two-component response regulator links rpf with biofilm formation and virulence of Xanthomonas axonopodis pv. citri.

    Directory of Open Access Journals (Sweden)

    Tzu-Pi Huang

    Full Text Available Citrus bacterial canker caused by Xanthomonas axonopodis pv. citri is a serious disease that impacts citrus production worldwide, and X. axonopodis pv. citri is listed as a quarantine pest in certain countries. Biofilm formation is important for the successful development of a pathogenic relationship between various bacteria and their host(s. To understand the mechanisms of biofilm formation by X. axonopodis pv. citri strain XW19, the strain was subjected to transposon mutagenesis. One mutant with a mutation in a two-component response regulator gene that was deficient in biofilm formation on a polystyrene microplate was selected for further study. The protein was designated as BfdR for biofilm formation defective regulator. BfdR from strain XW19 shares 100% amino acid sequence identity with XAC1284 of X. axonopodis pv. citri strain 306 and 30-100% identity with two-component response regulators in various pathogens and environmental microorganisms. The bfdR mutant strain exhibited significantly decreased biofilm formation on the leaf surfaces of Mexican lime compared with the wild type strain. The bfdR mutant was also compromised in its ability to cause canker lesions. The wild-type phenotype was restored by providing pbfdR in trans in the bfdR mutant. Our data indicated that BfdR did not regulate the production of virulence-related extracellular enzymes including amylase, lipase, protease, and lecithinase or the expression of hrpG, rfbC, and katE; however, BfdR controlled the expression of rpfF in XVM2 medium, which mimics cytoplasmic fluids in planta. In conclusion, biofilm formation on leaf surfaces of citrus is important for canker development in X. axonopodis pv. citri XW19. The process is controlled by the two-component response regulator BfdR via regulation of rpfF, which is required for the biosynthesis of a diffusible signal factor.

  3. The Strip-Hippo Pathway Regulates Synaptic Terminal Formation by Modulating Actin Organization at the Drosophila Neuromuscular Synapses

    Directory of Open Access Journals (Sweden)

    Chisako Sakuma

    2016-08-01

    Full Text Available Synapse formation requires the precise coordination of axon elongation, cytoskeletal stability, and diverse modes of cell signaling. The underlying mechanisms of this interplay, however, remain unclear. Here, we demonstrate that Strip, a component of the striatin-interacting phosphatase and kinase (STRIPAK complex that regulates these processes, is required to ensure the proper development of synaptic boutons at the Drosophila neuromuscular junction. In doing so, Strip negatively regulates the activity of the Hippo (Hpo pathway, an evolutionarily conserved regulator of organ size whose role in synapse formation is currently unappreciated. Strip functions genetically with Enabled, an actin assembly/elongation factor and the presumptive downstream target of Hpo signaling, to modulate local actin organization at synaptic termini. This regulation occurs independently of the transcriptional co-activator Yorkie, the canonical downstream target of the Hpo pathway. Our study identifies a previously unanticipated role of the Strip-Hippo pathway in synaptic development, linking cell signaling to actin organization.

  4. The anatomy of a star-forming galaxy: Pressure-driven regulation of star formation in simulated galaxies

    CERN Document Server

    Benincasa, S M; Couchman, H M P; Keller, B W

    2016-01-01

    We explore the regulation of star formation in star-forming galaxies through a suite of high-resolution isolated galaxy simulations. We use the SPH code GASOLINE, including photoelectric heating and metal cooling, which produces a multi-phase interstellar medium. We show that representative star formation and feedback sub-grid models naturally lead to a weak, sub-linear dependence between the amount of star formation and changes to star formation parameters. We incorporate these sub-grid models into an equilibrium pressure-driven regulation framework. We show that the sub-linear scaling arises as a consequence of the non-linear relationship between scale height and the effective pressure generated by stellar feedback. Thus, simulated star-formation regulation is sensitive to how well vertical structure in the ISM is resolved. Full galaxy disks experience density waves which drive locally time-dependent star formation. We develop a simple time-dependent, pressure-driven model that reproduces the response extre...

  5. The anatomy of a star-forming galaxy: pressure-driven regulation of star formation in simulated galaxies

    Science.gov (United States)

    Benincasa, S. M.; Wadsley, J.; Couchman, H. M. P.; Keller, B. W.

    2016-11-01

    We explore the regulation of star formation in star-forming galaxies through a suite of high-resolution isolated galaxy simulations. We use the smoothed particle hydrodynamics code GASOLINE, including photoelectric heating and metal cooling, which produces a multi-phase interstellar medium (ISM). We show that representative star formation and feedback sub-grid models naturally lead to a weak, sub-linear dependence between the amount of star formation and changes to star formation parameters. We incorporate these sub-grid models into an equilibrium pressure-driven regulation framework. We show that the sub-linear scaling arises as a consequence of the non-linear relationship between scaleheight and the effective pressure generated by stellar feedback. Thus, simulated star formation regulation is sensitive to how well vertical structure in the ISM is resolved. Full galaxy discs experience density waves which drive locally time-dependent star formation. We develop a simple time-dependent, pressure-driven model that reproduces the response extremely well.

  6. Staphylococcus aureus sarA regulates inflammation and colonization during central nervous system biofilm formation.

    Directory of Open Access Journals (Sweden)

    Jessica N Snowden

    Full Text Available Infection is a frequent and serious complication following the treatment of hydrocephalus with CSF shunts, with limited therapeutic options because of biofilm formation along the catheter surface. Here we evaluated the possibility that the sarA regulatory locus engenders S. aureus more resistant to immune recognition in the central nervous system (CNS based on its reported ability to regulate biofilm formation. We utilized our established model of CNS catheter-associated infection, similar to CSF shunt infections seen in humans, to compare the kinetics of bacterial titers, cytokine production and inflammatory cell influx elicited by wild type S. aureus versus an isogenic sarA mutant. The sarA mutant was more rapidly cleared from infected catheters compared to its isogenic wild type strain. Consistent with this finding, several pro-inflammatory cytokines and chemokines, including IL-17, CXCL1, and IL-1β were significantly increased in the brain following infection with the sarA mutant versus wild type S. aureus, in agreement with the fact that the sarA mutant displayed impaired biofilm growth and favored a planktonic state. Neutrophil influx into the infected hemisphere was also increased in the animals infected with the sarA mutant compared to wild type bacteria. These changes were not attributable to extracellular protease activity, which is increased in the context of SarA mutation, since similar responses were observed between sarA and a sarA/protease mutant. Overall, these results demonstrate that sarA plays an important role in attenuating the inflammatory response during staphylococcal biofilm infection in the CNS via a mechanism that remains to be determined.

  7. Role of Ordering Energy in Formation of Grain Structure and Special Boundaries Spectrum in OrderedAlloys with L12 Superstructure

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special boundaries in coincidence sites of ordered alloys. It was determined that the more energy of special boundaries in ordered alloys, the more energy of complex stacking fault. There is a correlation between the distribution of special boundaries as a function its relative energy and ordering energy: the more ordering energy, the more degree of washed away of distribution. The correlation between average relative energy of special boundaries and ordering energy was detected: the more ordering energy, the more average energy of special boundaries. The reverse dependence between ordering energy and average number of special boundaries in grains limited by boundaries of general type was discovered.

  8. Hh and Wnt signaling regulate formation of olig2+ neurons in the zebrafish cerebellum.

    Science.gov (United States)

    McFarland, Karen A; Topczewska, Jolanta M; Weidinger, Gilbert; Dorsky, Richard I; Appel, Bruce

    2008-06-01

    The cerebellum, which forms from anterior hindbrain, coordinates motor movements and balance. Sensory input from the periphery is relayed and modulated by cerebellar interneurons, which are organized in layers. The mechanisms that specify the different neurons of the cerebellum and direct its layered organization remain poorly understood. Drawing from investigations of spinal cord, we hypothesized that the embryonic cerebellum is patterned on the dorsoventral axis by opposing morphogens. We tested this using zebrafish. Here we show that expression of olig2, which encodes a bHLH transcription factor, marks a distinct subset of neurons with similarities to eurydendroid neurons, the principal efferent neurons of the teleost cerebellum. In combination with other markers, olig2 reveals a dorsoventral organization of cerebellar neurons in embryos. Disruption of Hedgehog signaling, which patterns the ventral neural tube, produced a two-fold increase in the number of olig2(+) neurons. By contrast, olig2(+) neurons did not develop in embryos deficient for Wnt signaling, which patterns dorsal neural tube, nor did they develop in embryos deficient for both Hedgehog and Wnt signaling. Our data indicate that Hedgehog and Wnt work in opposition across the dorsoventral axis of the cerebellum to regulate formation of olig2(+) neurons. Specifically, we propose that Hedgehog limits the range of Wnt signaling, which is necessary for olig2(+) neuron development.

  9. DICER Regulates the Formation and Maintenance of Cell-Cell Junctions in the Mouse Seminiferous Epithelium.

    Science.gov (United States)

    Korhonen, Hanna Maria; Yadav, Ram Prakash; Da Ros, Matteo; Chalmel, Frédéric; Zimmermann, Céline; Toppari, Jorma; Nef, Serge; Kotaja, Noora

    2015-12-01

    The endonuclease DICER that processes micro-RNAs and small interfering RNAs is essential for normal spermatogenesis and male fertility. We previously showed that the deletion of Dicer1 gene in postnatal spermatogonia in mice using Ngn3 promoter-driven Cre expression caused severe defects in the morphogenesis of haploid spermatid to mature spermatozoon, including problems in cell polarization and nuclear elongation. In this study, we further analyzed the same mouse model and revealed that absence of functional DICER in differentiating male germ cells induces disorganization of the cell-cell junctions in the seminiferous epithelium. We detected discontinuous and irregular apical ectoplasmic specializations between elongating spermatids and Sertoli cells. The defective anchoring of spermatids to Sertoli cells caused a premature release of spermatids into the lumen. Our findings may help also explain the abnormal elongation process of remaining spermatids because these junctions and the correct positioning of germ cells in the epithelium are critically important for the progression of spermiogenesis. Interestingly, cell adhesion-related genes were generally upregulated in Dicer1 knockout germ cells. Claudin 5 ( Cldn5 ) was among the most upregulated genes and we show that the polarized localization of CLAUDIN5 in the apical ectoplasmic specializations was lost in Dicer1 knockout spermatids. Our results suggest that DICER-dependent pathways control the formation and organization of cell-cell junctions in the seminiferous epithelium via the regulation of cell adhesion-related genes. PMID:26510868

  10. Clumpy high-z galaxies as a testbed for feedback-regulated galaxy formation

    CERN Document Server

    Mayer, Lucio; Lupi, Alessandro; Keller, Ben; Wadsley, James; Madau, Piero

    2016-01-01

    We study the dependence of fragmentation in massive gas-rich galaxy disks at $z > 1$ on feedback model and hydrodynamical method, employing the GASOLINE2 SPH code and the lagrangian mesh-less code GIZMO in finite mass mode. We compare non-cosmological galaxy disk runs with standard blastwave supernovae (SN)feedback, which introduces delayed cooling in order to drive winds, and runs with the new superbubble SN feedback, which produces winds naturally by modelling the detailed physics of SN-driven bubbles and leads to efficient self-regulation of star formation. We find that, with blastwave feedback, massive star forming clumps form in comparable number and with very similar masses in GASOLINE2 and GIZMO. The typical masses are in the range $10^7-10^8 M_{\\odot}$, lower than in most previous works, while giant clumps with masses above $10^9 M_{\\odot}$ are exceedingly rare. With superbubble feedback, instead, massive bound star forming clumps do not form because galaxies never undergo a phase of violent disk inst...

  11. Dynamin regulates metaphase furrow formation and plasma membrane compartmentalization in the syncytial Drosophila embryo

    Directory of Open Access Journals (Sweden)

    Richa Rikhy

    2015-02-01

    Full Text Available The successive nuclear division cycles in the syncytial Drosophila embryo are accompanied by ingression and regression of plasma membrane furrows, which surround individual nuclei at the embryo periphery, playing a central role in embryo compartmentalization prior to cellularization. Here, we demonstrate that cell cycle changes in dynamin localization and activity at the plasma membrane (PM regulate metaphase furrow formation and PM organization in the syncytial embryo. Dynamin was localized on short PM furrows during interphase, mediating endocytosis of PM components. Dynamin redistributed off ingressed PM furrows in metaphase, correlating with stabilized PM components and the associated actin regulatory machinery on long furrows. Acute inhibition of dynamin in the temperature sensitive shibire mutant embryo resulted in morphogenetic consequences in the syncytial division cycle. These included inhibition of metaphase furrow ingression, randomization of proteins normally polarized to intercap PM and disruption of the diffusion barrier separating PM domains above nuclei. Based on these findings, we propose that cell cycle changes in dynamin orchestrate recruitment of actin regulatory machinery for PM furrow dynamics during the early mitotic cycles in the Drosophila embryo.

  12. The SILCC project: III. Regulation of star formation and outflows by stellar winds and supernovae

    CERN Document Server

    Gatto, A; Naab, T; Girichidis, P; Wünsch, R; Glover, S C O; Klessen, R S; Clark, P C; Peters, T; Derigs, D; Baczynski, C; Puls, J

    2016-01-01

    We study the impact of stellar winds and supernovae on the multi-phase interstellar medium using three-dimensional hydrodynamical simulations carried out with FLASH. The selected galactic disc region has a size of (500 pc)$^2$ x $\\pm$ 5 kpc and a gas surface density of 10 M$_{\\odot}$/pc$^2$. The simulations include an external stellar potential and gas self-gravity, radiative cooling and diffuse heating, sink particles representing star clusters, stellar winds from these clusters which combine the winds from indi- vidual massive stars by following their evolution tracks, and subsequent supernova explosions. Dust and gas (self-)shielding is followed to compute the chemical state of the gas with a chemical network. We find that stellar winds can regulate star (cluster) formation. Since the winds suppress the accretion of fresh gas soon after the cluster has formed, they lead to clusters which have lower average masses (10$^2$ - 10$^{4.3}$ M$_{\\odot}$) and form on shorter timescales (10$^{-3}$ - 10 Myr). In part...

  13. The Enterococcus faecium enterococcal biofilm regulator, EbrB, regulates the esp operon and is implicated in biofilm formation and intestinal colonization.

    Directory of Open Access Journals (Sweden)

    Janetta Top

    Full Text Available Nowadays, Enterococcus faecium is one of the leading nosocomial pathogens worldwide. Strains causing clinical infections or hospital outbreaks are enriched in the enterococcal surface protein (Esp encoding ICEEfm1 mobile genetic element. Previous studies showed that Esp is involved in biofilm formation, endocarditis and urinary tract infections. In this study, we characterized the role of the putative AraC type of regulator (locus tag EfmE1162_2351, which we renamed ebrB and which is, based on the currently available whole genome sequences, always located upstream of the esp gene, and studied its role in Esp surface exposure during growth. A markerless deletion mutant of ebrB resulted in reduced esp expression and complete abolishment of Esp surface exposure, while Esp cell-surface exposure was restored when this mutant was complemented with an intact copy of ebrB. This demonstrates a role for EbrB in esp expression. However, during growth, ebrB expression levels did not change over time, while an increase in esp expression at both RNA and protein level was observed during mid-log and late-log phase. These results indicate the existence of a secondary regulation system for esp, which might be an unknown quorum sensing system as the enhanced esp expression seems to be cell density dependent. Furthermore, we determined that esp is part of an operon of at least 3 genes putatively involved in biofilm formation. A semi-static biofilm model revealed reduced biofilm formation for the EbrB deficient mutant, while dynamics of biofilm formation using a flow cell system revealed delayed biofilm formation in the ebrB mutant. In a mouse intestinal colonization model the ebrB mutant was less able to colonize the gut compared to wild-type strain, especially in the small intestine. These data indicate that EbrB positively regulates the esp operon and is implicated in biofilm formation and intestinal colonization.

  14. The mediator complex subunit Med10 regulates heart valve formation in zebrafish by controlling Tbx2b-mediated Has2 expression and cardiac jelly formation.

    Science.gov (United States)

    Just, Steffen; Hirth, Sofia; Berger, Ina M; Fishman, Mark C; Rottbauer, Wolfgang

    2016-09-01

    In search for novel key regulators of cardiac valve formation, we isolated the zebrafish cardiac valve mutant ping pong (png). We find that an insertional promoter mutation within the zebrafish mediator complex subunit 10 (med10) gene is leading to impaired heart valve formation. Expression of the T-box transcription factor 2b (Tbx2b), known to be essential in cardiac valve development, is severely reduced in png mutant hearts. We demonstrate here that transient reconstitution of Tbx2b expression rescues AV canal development in png mutant zebrafish. By contrast, overexpression of Forkhead box N4 (Foxn4), a known upstream regulator of Tbx2b, is not capable to reconstitute tbx2b expression and heart valve formation in Med10-deficient png mutant hearts. Interestingly, hyaluronan synthase 2 (has2), a known downstream target of Tbx2 and producer of hyaluronan (HA) - a major ECM component of the cardiac jelly and critical for proper heart valve development - is completely absent in ping pong mutant hearts. We propose here a rather unique role of Med10 in orchestrating cardiac valve formation by mediating Foxn4 dependent tbx2b transcription, expression of Has2 and subsequently proper development of the cardiac jelly. PMID:27343557

  15. Influence of zinc dialkyldithiophosphate tribofilm formation on the tribological performance of self-mated diamond-like carbon contacts under boundary lubrication

    International Nuclear Information System (INIS)

    Diamond-like carbon (DLC) coatings offer excellent mechanical and tribological properties that make them suitable protective coatings for various industrial applications. In recent years, several engine and power train components in passenger cars, which work under boundary lubricated conditions, have been coated with DLC coatings. Since conventional lubricants and lubricant additives are formulated for metal surfaces, there are still controversial questions concerning chemical reactivity between DLC surfaces and common lubricant additives owing to the chemical inertness of DLC coatings. In this work, we present the influence of zinc dialkyldithiophosphate (ZnDTP) anti-wear additives on the tribological performance of various self-mated DLC coatings under boundary lubrication conditions. The effects of hydrogen, doping elements, and surface morphology on the reactivity of DLC coatings to form a ZnDTP-derived tribofilm were investigated by atomic force microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The results confirmed that ZnDTP-derived pad-like or patchy tribofilm forms on the surfaces depending on the DLC coating. It is seen that hydrogen content and doping elements increase pad-like tribofilm formation. Doped DLC coatings are found to give better wear resistance than non-doped DLC coatings. Furthermore, the addition of ZnDTP additives to the base oil significantly improves the wear resistance of hydrogenated DLC, silicon-doped hydrogenated DLC, and chromium-doped hydrogenated DLC. Hydrogen-free tetrahedral amorphous DLC coatings provide the lowest friction coefficient both in PAO (poly-alpha-olefin) and PAO + ZnDTP oils. - Highlights: • Zinc dialkyldithiophosphate (DTP) tribofilm formation on various DLC surfaces was evidenced. • Pad-like tribofilm was found on a-C:H, a-C, Si-DLC and Cr-DLC. • Pad-like tribofilm on DLC surfaces greatly increased the wear resistance. • Hydrogenated and doped DLC coatings are

  16. Influence of zinc dialkyldithiophosphate tribofilm formation on the tribological performance of self-mated diamond-like carbon contacts under boundary lubrication

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah Tasdemir, H., E-mail: habdullah46@gmail.com [Department of Mechanical Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Tokoroyama, Takayuki; Kousaka, Hiroyuki; Umehara, Noritsugu [Department of Mechanical Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Mabuchi, Yutaka [Nissan Motor Co. (Japan)

    2014-07-01

    Diamond-like carbon (DLC) coatings offer excellent mechanical and tribological properties that make them suitable protective coatings for various industrial applications. In recent years, several engine and power train components in passenger cars, which work under boundary lubricated conditions, have been coated with DLC coatings. Since conventional lubricants and lubricant additives are formulated for metal surfaces, there are still controversial questions concerning chemical reactivity between DLC surfaces and common lubricant additives owing to the chemical inertness of DLC coatings. In this work, we present the influence of zinc dialkyldithiophosphate (ZnDTP) anti-wear additives on the tribological performance of various self-mated DLC coatings under boundary lubrication conditions. The effects of hydrogen, doping elements, and surface morphology on the reactivity of DLC coatings to form a ZnDTP-derived tribofilm were investigated by atomic force microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The results confirmed that ZnDTP-derived pad-like or patchy tribofilm forms on the surfaces depending on the DLC coating. It is seen that hydrogen content and doping elements increase pad-like tribofilm formation. Doped DLC coatings are found to give better wear resistance than non-doped DLC coatings. Furthermore, the addition of ZnDTP additives to the base oil significantly improves the wear resistance of hydrogenated DLC, silicon-doped hydrogenated DLC, and chromium-doped hydrogenated DLC. Hydrogen-free tetrahedral amorphous DLC coatings provide the lowest friction coefficient both in PAO (poly-alpha-olefin) and PAO + ZnDTP oils. - Highlights: • Zinc dialkyldithiophosphate (DTP) tribofilm formation on various DLC surfaces was evidenced. • Pad-like tribofilm was found on a-C:H, a-C, Si-DLC and Cr-DLC. • Pad-like tribofilm on DLC surfaces greatly increased the wear resistance. • Hydrogenated and doped DLC coatings are

  17. PtdIns(3,4,5)P3 is a regulator of myosin-X localization and filopodia formation

    DEFF Research Database (Denmark)

    Plantard, Laure; Arjonen, Antti; Lock, John G;

    2010-01-01

    Phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P3] is a key regulator of cell signaling that acts by recruiting proteins to the cell membrane, such as at the leading edge during cell migration. Here, we show that PtdIns (3,4,5)P3 plays a central role in filopodia formation via the bindi...

  18. Differential Regulation of c-di-GMP Metabolic Enzymes by Environmental Signals Modulates Biofilm Formation in Yersinia pestis.

    Science.gov (United States)

    Ren, Gai-Xian; Fan, Sai; Guo, Xiao-Peng; Chen, Shiyun; Sun, Yi-Cheng

    2016-01-01

    Cyclic diguanylate (c-di-GMP) is essential for Yersinia pestis biofilm formation, which is important for flea-borne blockage-dependent plague transmission. Two diguanylate cyclases (DGCs), HmsT and HmsD and one phosphodiesterase (PDE), HmsP are responsible for the synthesis and degradation of c-di-GMP in Y. pestis. Here, we systematically analyzed the effect of various environmental signals on regulation of the biofilm phenotype, the c-di-GMP levels, and expression of HmsT, HmsD, and HmsP in Y. pestis. Biofilm formation was higher in the presence of non-lethal high concentration of CaCl2, MgCl2, CuSO4, sucrose, sodium dodecyl sulfate, or dithiothreitol, and was lower in the presence of FeCl2 or NaCl. In addition, we found that HmsD plays a major role in biofilm formation in acidic or redox environments. These environmental signals differentially regulated expression of HmsT, HmsP and HmsD, resulting in changes in the intracellular levels of c-di-GMP in Y. pestis. Our results suggest that bacteria can sense various environmental signals, and differentially regulate activity of DGCs and PDEs to coordinately regulate and adapt metabolism of c-di-GMP and biofilm formation to changing environments.

  19. Differential regulation of c-di-GMP metabolic enzymes by environmental signals modulates biofilm formation in Yersinia pestis

    Directory of Open Access Journals (Sweden)

    Gai-Xian eRen

    2016-06-01

    Full Text Available Cyclic diguanylate (c-di-GMP is essential for Yersinia pestis biofilm formation, which is important for flea-borne blockage-dependent plague transmission. Two diguanylate cyclases (DGCs, HmsT and HmsD and one phosphodiesterase (PDE, HmsP are responsible for the synthesis and degradation of c-di-GMP in Y. pestis. Here, we systematically analyzed the effect of various environmental signals on regulation of the biofilm phenotype, the c-di-GMP levels, and expression of HmsT, HmsD and HmsP in Y. pestis. Biofilm formation was higher in the presence of nonlethal high concentration of CaCl2, MgCl2, CuSO4, sucrose, sodium dodecyl sulfonate, or dithiothreitol, and was lower in the presence of FeCl2 or NaCl. In addition, we found that HmsD plays a major role in biofilm formation in acidic or redox environments. These environmental signals differentially regulated expression of HmsT, HmsP and HmsD, resulting in changes in the intracellular levels of c-di-GMP in Y. pestis. Our results suggest that bacteria can sense various environmental signals, and differentially regulates their DGCs and PDEs to coordinately regulate and adapt metabolism of c-di-GMP and biofilm formation to changing environments.

  20. NMDA Receptor- and ERK-Dependent Histone Methylation Changes in the Lateral Amygdala Bidirectionally Regulate Fear Memory Formation

    Science.gov (United States)

    Gupta-Agarwal, Swati; Jarome, Timothy J.; Fernandez, Jordan; Lubin, Farah D.

    2014-01-01

    It is well established that fear memory formation requires de novo gene transcription in the amygdala. We provide evidence that epigenetic mechanisms in the form of histone lysine methylation in the lateral amygdala (LA) are regulated by NMDA receptor (NMDAR) signaling and involved in gene transcription changes necessary for fear memory…

  1. The Ubiquitin-Specific Protease 14 (USP14) Is a Critical Regulator of Long-Term Memory Formation

    Science.gov (United States)

    Jarome, Timothy J.; Kwapis, Janine L.; Hallengren, Jada J.; Wilson, Scott M.; Helmstetter, Fred J.

    2014-01-01

    Numerous studies have suggested a role for ubiquitin-proteasome-mediated protein degradation in learning-dependent synaptic plasticity; however, very little is known about how protein degradation is regulated at the level of the proteasome during memory formation. The ubiquitin-specific protease 14 (USP14) is a proteasomal deubiquitinating enzyme…

  2. Nuclear translocation of phosphorylated STAT3 regulates VEGF-A-induced lymphatic endothelial cell migration and tube formation

    Energy Technology Data Exchange (ETDEWEB)

    Okazaki, Hideki; Tokumaru, Sho; Hanakawa, Yasushi; Shiraishi, Ken; Shirakata, Yuji; Dai, Xiuju; Yang, Lijun; Tohyama, Mikiko; Hashimoto, Koji [Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295 (Japan); Sayama, Koji, E-mail: sayama@m.ehime-u.ac.jp [Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295 (Japan)

    2011-09-02

    Highlights: {yields} VEGF-A enhanced lymphatic endothelial cell migration and increased tube formation. {yields} VEGF-A treated lymphatic endothelial cell showed activation of STAT3. {yields} Dominant-negative STAT3 inhibited VEGF-A-induced lymphatic endothelial cell migration and tube formation. -- Abstract: Vascular endothelial growth factor (VEGF) is an endothelial cell-specific growth factor that regulates endothelial functions, and signal transducers and activators of transcription (STATs) are known to be important during VEGF receptor signaling. The aim of this study was to determine whether STAT3 regulates VEGF-induced lymphatic endothelial cell (LEC) migration and tube formation. VEGF-A (33 ng/ml) enhanced LEC migration by 2-fold and increased tube length by 25% compared with the control, as analyzed using a Boyden chamber and Matrigel assay, respectively. Western blot analysis and immunostaining revealed that VEGF-A induced the nuclear translocation of phosphorylated STAT3 in LECs, and this translocation was blocked by the transfection of LECs with an adenovirus vector expressing a dominant-negative mutant of STAT3 (Ax-STAT3F). Transfection with Ax-STAT3F also almost completely inhibited VEGF-A-induced LEC migration and tube formation. These results indicate that STAT3 is essential for VEGF-A-induced LEC migration and tube formation and that STAT3 regulates LEC functions.

  3. WEREWOLF, a regulator of root hair pattern formation, controls flowering time through the regulation of FT mRNA stability.

    Science.gov (United States)

    Seo, Eunjoo; Yu, Jihyeon; Ryu, Kook Hui; Lee, Myeong Min; Lee, Ilha

    2011-08-01

    A key floral activator, FT, integrates stimuli from long-day, vernalization, and autonomous pathways and triggers flowering by directly regulating floral meristem identity genes in Arabidopsis (Arabidopsis thaliana). Since a small amount of FT transcript is sufficient for flowering, the FT level is strictly regulated by diverse genes. In this study, we show that WEREWOLF (WER), a MYB transcription factor regulating root hair pattern, is another regulator of FT. The mutant wer flowers late in long days but normal in short days and shows a weak sensitivity to vernalization, which indicates that WER controls flowering time through the photoperiod pathway. The expression and double mutant analyses showed that WER modulates FT transcript level independent of CONSTANS and FLOWERING LOCUS C. The histological analysis of WER shows that it is expressed in the epidermis of leaves, where FT is not expressed. Consistently, WER regulates not the transcription but the stability of FT mRNA. Our results reveal a novel regulatory mechanism of FT that is non cell autonomous.

  4. Direct and indirect regulation of spinal cord Ia afferent terminal formation by the γ-Protocadherins

    Directory of Open Access Journals (Sweden)

    Tuhina ePrasad

    2011-12-01

    Full Text Available The Pcdh-γ gene cluster encodes 22 protocadherin adhesion molecules that interact as homophilic multimers and critically regulate synaptogenesis and apoptosis of interneurons in the developing spinal cord. Unlike interneurons, the two primary components of the monosynaptic stretch reflex circuit, dorsal root ganglion sensory neurons and ventral motor neurons, do not undergo excessive apoptosis in Pcdh-γdel/del null mutants, which die shortly after birth. However, as we show here, mutants exhibit severely disorganized Ia proprioceptive afferent terminals in the ventral horn. In contrast to the fine net-like pattern observed in wild-type mice, central Ia terminals in Pcdh-γ mutants are expanded, clumped, and fill the space between individual motor neurons; quantitative analysis shows a ~2.5 fold increase in the area of terminals. Concomitant with this, there is a 70% loss of the collaterals that Ia afferents extend to ventral interneurons, many of which undergo apoptosis in the mutants. The Ia afferent phenotype is ameliorated, though not entirely rescued, when apoptosis is blocked in Pcdh-γ null mice by introduction of a Bax null allele. This indicates that loss of ventral interneurons, which act as intermediate Ia afferent targets, contributes to the disorganization of terminals on motor pools. Restricted mutation of the Pcdh-γ cluster using conditional mutants and multiple Cre transgenic lines (Wnt1-Cre for sensory neurons; Pax2-Cre for ventral interneurons; Hb9-Cre for motor neurons also revealed a direct requirement for the γ-Pcdhs in Ia neurons and ventral interneurons, but not in motor neurons themselves. Together, these genetic manipulations indicate that the γ-Pcdhs are required for the formation of the Ia afferent circuit in two ways: First, they control the survival of ventral interneurons that act as intermediate Ia targets; and second, they provide a homophilic molecular cue between Ia afferents and target ventral interneurons.

  5. 一种编队控制的动态调整与规划方法%A Dynamic Regulation and Scheduling Scheme for Formation Control

    Institute of Scientific and Technical Information of China (English)

    陈余庆; 庄严; 王伟

    2007-01-01

    This article is concerned with cooperative control problems in formation of mobile robots under the nonholonomic constraints that certain geometrical constraints are imposed on multiple mobile robots throughout their travel. For this purpose, a new method of motion control for formation is presented, which is based on the dynamic regulation and scheduling scheme. It is attractive for its adaptability to the formation structure and desired trajectory. The quality of formation keeping can be evaluated by the instantaneous errors of formation offset and spacing distance. Some kinematics laws are developed to regulate and maintain the formation shape. Simulation results and data analysis show the validity of the proposed approach for a group of robots.

  6. Receptor-Type Guanylyl Cyclase at 76C (Gyc76C) Regulates De Novo Lumen Formation during Drosophila Tracheal Development

    Science.gov (United States)

    Patel, Unisha

    2016-01-01

    Lumen formation and maintenance are important for the development and function of essential organs such as the lung, kidney and vasculature. In the Drosophila embryonic trachea, lumena form de novo to connect the different tracheal branches into an interconnected network of tubes. Here, we identify a novel role for the receptor type guanylyl cyclase at 76C (Gyc76C) in de novo lumen formation in the Drosophila trachea. We show that in embryos mutant for gyc76C or its downsteam effector protein kinase G (PKG) 1, tracheal lumena are disconnected. Dorsal trunk (DT) cells of gyc76C mutant embryos migrate to contact each other and complete the initial steps of lumen formation, such as the accumulation of E-cadherin (E-cad) and formation of an actin track at the site of lumen formation. However, the actin track and E-cad contact site of gyc76C mutant embryos did not mature to become a new lumen and DT lumena did not fuse. We also observed failure of the luminal protein Vermiform to be secreted into the site of new lumen formation in gyc76C mutant trachea. These DT lumen formation defects were accompanied by altered localization of the Arf-like 3 GTPase (Arl3), a known regulator of vesicle-vesicle and vesicle-membrane fusion. In addition to the DT lumen defect, lumena of gyc76C mutant terminal cells were shorter compared to wild-type cells. These studies show that Gyc76C and downstream PKG-dependent signaling regulate de novo lumen formation in the tracheal DT and terminal cells, most likely by affecting Arl3-mediated luminal secretion. PMID:27642749

  7. Genetic interaction of two abscisic acid signaling regulators, HY5 and FIERY1, in mediating lateral root formation

    KAUST Repository

    Chen, Hao

    2011-01-01

    Root architecture is continuously shaped in a manner that helps plants to better adapt to the environment. Gene regulation at the transcriptional or post-transcriptional levels largely controls this environmental response. Recently, RNA silencing has emerged as an important player in gene regulation and is involved in many aspects of plant development, including lateral root formation. In a recent study, we found that FIERY1, a bifunctional abiotic stress and abscisic acid (ABA) signaling regulator and an endogenous RNA silencing suppressor, mediates auxin response during lateral root formation in Arabidopsis. We proposed that FRY1 regulates lateral root development through its activity on adenosine 3,5-bisphosphate (PAP), a strong inhibitor of exoribonucleases (XRNs). Interestingly, some of the phenotypes of fry1, such as enhanced response to light in repressing hypocotyl elongation and hypersensitivity to ABA in lateral root growth, are opposite to those of another light- and ABA-signaling mutant, hy5. Here we analyzed the hy5 fry1 double mutant for root and hypocotyl growth. We found that the hy5 mutation can suppress the enhanced light sensitivity in fry1 hypocotyl elongation and restore the lateral root formation. The genetic interaction between HY5 and FRY1 indicates that HY5 and FRY1 may act in overlapping pathways that mediate light signaling and lateral root development. © 2011 Landes Bioscience.

  8. Grainyhead-like factor Get1/Grhl3 regulates formation of the epidermal leading edge during eyelid closure.

    Science.gov (United States)

    Yu, Zhengquan; Bhandari, Ambica; Mannik, Jaana; Pham, Thu; Xu, Xiaoman; Andersen, Bogi

    2008-07-01

    Grainyhead transcription factors play an evolutionarily conserved role in regulating epidermal terminal differentiation. One such factor, the mammalian Grainyhead-like epithelial transactivator (Get1/Grhl3), is important for epidermal barrier formation. In addition to a role in barrier formation, Grainyhead genes play roles in closure of several structures such as the mouse neural tube and Drosophila wounds. Consistent with these observations, we found that Get1 knockout mice have an eye-open at birth phenotype. The failure of eyelid closure appears to be due to critical functions of Get1 in promoting F-actin polymerization, filopodia formation, and the cell shape changes that are required for migration of the keratinocytes at the leading edge during eyelid closure. The expression of TGFalpha, a known regulator of leading edge formation, is decreased in the eyelid tip of Get1(-/-) mice. Levels of phospho-EGFR and phospho-ERK are also decreased at the leading edge tip. Furthermore, in an organ culture model, TGFalpha can increase levels of phospho-EGFR and promote cell shape changes as well as leading edge formation in Get1(-/-) eyelids, indicating that in eyelid closure Get1 acts upstream of TGFalpha in the EGFR/ERK pathway.

  9. Regulation of ATP-dependent P-(Ser)-HPr formation in Streptococcus mutans and Streptococcus salivarius.

    Science.gov (United States)

    Thevenot, T; Brochu, D; Vadeboncoeur, C; Hamilton, I R

    1995-01-01

    Sugar transport via the phosphoenolpyruvate (PEP) phosphotransferase system involves PEP-dependent phosphorylation of the general phosphotransferase system protein, HPr, at histidine 15. However, gram-positive bacteria can also carry out ATP-dependent phosphorylation of HPr at serine 46 by means of (Ser)HPr kinase. In this study, we demonstrate that (Ser)HPr kinase in crude preparations of Streptococcus mutans Ingbritt and Streptococcus salivarius ATCC 25975 is membrane associated, with pH optima of 7.0 and 7.5, respectively. The latter organism possessed 7- to 27-fold-higher activity than S. mutans NCTC 10449, GS-5, and Ingbritt strains. The enzyme in S. salivarius was activated by fructose-1,6-bisphosphate (FBP) twofold with 0.05 mM ATP, but this intermediate was slightly inhibitory with 1.0 mM ATP at FBP concentrations up to 10 mM. Similar inhibition was observed with the enzyme from S. mutans Ingbritt. A variety of other glycolytic intermediates had no effect on kinase activity under these conditions. The activity and regulation of (Ser)HPr kinase were assessed in vivo by monitoring P-(Ser)-HPr formation in steady-state cells of S. mutans Ingbritt grown in continuous culture with limiting glucose (10 and 50 mM) and with excess glucose (100 and 200 mM). All four forms of HPr [free HPr, P approximately (His)-HPr, P-(Ser)-HPr, and P approximately (His)-P-(Ser)-HPr] could be detected in the cells; however, significant differences in the intracellular levels of the forms were apparent during growth at different glucose concentrations. The total HPr pool increased with increasing concentrations of glucose in the medium, with significant increases in the P-(Ser)-HPr and P approximately HHis)-P-(Ser)-HPr concentrations. For example, while total PEP-dependent phosphorylation [P approximately(His)-HPr plus P approximately (His)-P-(Ser)-HPr] varied only from 21.5 to 52.5 microgram mg of cell protein (-1) in cells grown at the four glucose concentrations, the total ATP

  10. Comprehensive transcriptome analysis unravels the existence of crucial genes regulating primary metabolism during adventitious root formation in Petunia hybrida.

    Directory of Open Access Journals (Sweden)

    Amirhossein Ahkami

    Full Text Available To identify specific genes determining the initiation and formation of adventitious roots (AR, a microarray-based transcriptome analysis in the stem base of the cuttings of Petunia hybrida (line W115 was conducted. A microarray carrying 24,816 unique, non-redundant annotated sequences was hybridized to probes derived from different stages of AR formation. After exclusion of wound-responsive and root-regulated genes, 1,354 of them were identified which were significantly and specifically induced during various phases of AR formation. Based on a recent physiological model distinguishing three metabolic phases in AR formation, the present paper focuses on the response of genes related to particular metabolic pathways. Key genes involved in primary carbohydrate metabolism such as those mediating apoplastic sucrose unloading were induced at the early sink establishment phase of AR formation. Transcriptome changes also pointed to a possible role of trehalose metabolism and SnRK1 (sucrose non-fermenting 1- related protein kinase in sugar sensing during this early step of AR formation. Symplastic sucrose unloading and nucleotide biosynthesis were the major processes induced during the later recovery and maintenance phases. Moreover, transcripts involved in peroxisomal beta-oxidation were up-regulated during different phases of AR formation. In addition to metabolic pathways, the analysis revealed the activation of cell division at the two later phases and in particular the induction of G1-specific genes in the maintenance phase. Furthermore, results point towards a specific demand for certain mineral nutrients starting in the recovery phase.

  11. Spatial Regulation of Gene Expression in Neurons During Synapse Formation and Synaptic Plasticity

    OpenAIRE

    Kim, Sangmok

    2013-01-01

    mRNA localization and regulated translation allow individual neurons to locally regulate the proteome of each of their many subcellular compartments. To investigate the spatial regulation of gene expression during synaptic plasticity, we used a translational reporter system to demonstrate synapse- and stimulus-specific translation during long-term facilitation of Aplysia sensory-motor synapse. These studies revealed a role for a retrograde signal from the postsynaptic motor neuron in regulati...

  12. Negative carbon isotopic excursion on the Lower/Middle Cambrian boundary of Kaili Formation, Taijiang County,Guizhou Province, China: Implications for mass extinction and stratigraphic division and correlation

    Institute of Scientific and Technical Information of China (English)

    杨瑞东; 朱立军; 王世杰

    2003-01-01

    The stratigraphic division and correlation of the Lower/Middle Cambrian boundary is a global problem that has not yet been perfectly solved up to now. That is because there existed two global biogeographic regions during the period from Early Cambrian to Middle Cambrian. Although much work has been done from the angle of paleontology and great achievements have been acquired in this aspect, no biological assemblage has yet been established for global stratigraphic correlations due to the coexistence of the two global biogeographic regions -- the Atlantic biogeographic region and the Indian-Pacific biogeographic region during the Early-Middle Cambrian. So, to develop and establish other approaches to the stratigraphic division and correlation of the Lower/Middle Cambrian on a global scale is a possible way to solve the puzzling problem. This work systematically studied acritarch fossils from the Early-Middle Cambrian Kaili Formation at Taijiang County, Guizhou Province. The Lower/Middle Cambrian boundary was divided in terms of acritarch fossil assemblage. The divided boundary is generally consistent with what was divided by trilobite and can be correlated with the Lower/Middle Cambrian boundaries divided by acritarch assemblage in Siberia and Europe. On this basis, the Lower/Middle Cambrian boundary is divided in terms of an obvious carbon isotopic excursion on a global scale during the transitional period from Early Cambrian to Middle Cambrian boundaries in Siberia and North America. The method for the stratigraphic division and correlation of the Lower/Middle Cambrian boundary in terms of carbon isotopic oscillations is helpful to solving the global problem on the division and correlation of the Lower/Middle Cambrian boundary. It is also evidenced that the extinction of a lot of trilobites at the end of Early Cambrian is closely related with this event of carbon isotopic excursion.

  13. Retinyl Ester Formation by Lecithin:Retinol Acyltransferase Is a Key Regulator of Retinoid Homeostasis in Mouse Embryogenesis* s

    OpenAIRE

    Kim, Youn-Kyung; Wassef, Lesley; Hamberger, Leora; Piantedosi, Roseann; Palczewski, Krzysztof; Blaner, William S.; Quadro, Loredana

    2007-01-01

    The developing mammalian embryo is entirely dependent on the maternal circulation for its supply of retinoids (vitamin A and its metabolites). The mechanisms through which mammalian developing tissues maintain adequate retinoid levels in the face of suboptimal or excessive maternal dietary vitamin A intake have not been established. We investigated the role of retinyl ester formation catalyzed by lecithin:retinol acyltransferase (LRAT) in regulating retinoid homeostasis during embryogenesis. ...

  14. A Genome-wide RNAi Screen for Microtubule Bundle Formation and Lysosome Motility Regulation in Drosophila S2 Cells

    OpenAIRE

    Amber L. Jolly; Chi-Hao Luan; Brendon E. Dusel; Sara F. Dunne; Michael Winding; Vishrut J. Dixit; Chloe Robins; Jennifer L. Saluk; David J. Logan; Anne E. Carpenter; Manu Sharma; Deborah Dean; Andrew R. Cohen; Vladimir I. Gelfand

    2016-01-01

    Long-distance intracellular transport of organelles, mRNA, and proteins (“cargo”) occurs along the microtubule cytoskeleton by the action of kinesin and dynein motor proteins, but the vast network of factors involved in regulating intracellular cargo transport are still unknown. We capitalize on the Drosophila melanogaster S2 model cell system to monitor lysosome transport along microtubule bundles, which require enzymatically active kinesin-1 motor protein for their formation. We use an auto...

  15. A genome-wide RNAi screen for microtubule bundle formation and lysosome motility regulation in Drosophila S2 cells

    OpenAIRE

    Jolly, Amber L.; Luan, Chi-Hao; Dusel, Brendon E.; Dunne, Sara Fernandez; Winding, Michael; Dixit, Vishrut J.; Robins, Chloe; Saluk, Jennifer L.; Logan, David J.; Carpenter, Anne E.; Sharma, Manu; Dean, Deborah; Cohen, Andrew R.; Gelfand, Vladimir I.

    2016-01-01

    Long-distance intracellular transport of organelles, mRNA, and proteins (“cargo”) occurs along the microtubule cytoskeleton by the action of kinesin and dynein motor proteins; the vast network of factors involved in regulating intracellular cargo transport are still unknown. We capitalize on the Drosophila melanogaster S2 model cell system to monitor lysosome transport along microtubule bundles, which require enzymatically active kinesin-1 motor protein for their formation. We use an automate...

  16. The Sensor Kinase GacS Negatively Regulates Flagellar Formation and Motility in a Biocontrol Bacterium, Pseudomonas chlororaphis O6

    Directory of Open Access Journals (Sweden)

    Ji Soo Kim

    2014-06-01

    Full Text Available The GacS/GacA two component system regulates various traits related to the biocontrol potential of plant-associated pseudomonads. The role of the sensor kinase, GacS, differs between strains in regulation of motility. In this study, we determined how a gacS mutation changed cell morphology and motility in Pseudomonas chlororaphis O6. The gacS mutant cells were elongated in stationary-phase compared to the wild type and the complemented gacS mutant, but cells did not differ in length in logarithmic phase. The gacS mutant had a two-fold increase in the number of flagella compared with the wild type strain; flagella number was restored to that of the wild type in the complemented gacS mutant. The more highly flagellated gacS mutant cells had greater swimming motilities than that of the wild type strain. Enhanced flagella formation in the gacS mutant correlated with increased expression of three genes, fleQ, fliQ and flhF, involved in flagellar formation. Expression of these genes in the complemented gacS mutant was similar to that of the wild type. These findings show that this root-colonizing pseudomonad adjusts flagella formation and cell morphology in stationary-phase using GacS as a major regulator.

  17. Phosphorylation of K[superscript +] Channels at Single Residues Regulates Memory Formation

    Science.gov (United States)

    Vernon, Jeffrey; Irvine, Elaine E.; Peters, Marco; Jeyabalan, Jeshmi; Giese, K. Peter

    2016-01-01

    Phosphorylation is a ubiquitous post-translational modification of proteins, and a known physiological regulator of K[superscript +] channel function. Phosphorylation of K[superscript +] channels by kinases has long been presumed to regulate neuronal processing and behavior. Although circumstantial evidence has accumulated from behavioral studies…

  18. GAS REGULATION OF GALAXIES: THE EVOLUTION OF THE COSMIC SPECIFIC STAR FORMATION RATE, THE METALLICITY-MASS-STAR-FORMATION RATE RELATION, AND THE STELLAR CONTENT OF HALOS

    Energy Technology Data Exchange (ETDEWEB)

    Lilly, Simon J.; Carollo, C. Marcella; Pipino, Antonio; Peng Yingjie [Institute for Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Renzini, Alvio [Department of Physics and Astronomy Galileo Galilei, Universita degli Studi di Padova, via Marzolo 8, I-35131 Padova (Italy)

    2013-08-01

    A very simple physical model of galaxies is one in which the formation of stars is instantaneously regulated by the mass of gas in a reservoir with mass loss scaling with the star-formation rate (SFR). This model links together three different aspects of the evolving galaxy population: (1) the cosmic time evolution of the specific star-formation rate (sSFR) relative to the growth of halos, (2) the gas-phase metallicities across the galaxy population and over cosmic time, and (3) the ratio of the stellar to dark matter mass of halos. The gas regulator is defined by the gas consumption timescale ({epsilon}{sup -1}) and the mass loading {lambda} of the wind outflow {lambda}{center_dot}SFR. The simplest regulator, in which {epsilon} and {lambda} are constant, sets the sSFR equal to exactly the specific accretion rate of the galaxy; more realistic situations lead to an sSFR that is perturbed from this precise relation. Because the gas consumption timescale is shorter than the timescale on which the system evolves, the metallicity Z is set primarily by the instantaneous operation of the regulator system rather than by the past history of the system. The metallicity of the gas reservoir depends on {epsilon}, {lambda}, and sSFR, and the regulator system therefore naturally produces a Z(m{sub star}, SFR) relation if {epsilon} and {lambda} depend on the stellar mass m{sub star}. Furthermore, this relation will be the same at all epochs unless the parameters {epsilon} and {lambda} themselves change with time. A so-called fundamental metallicity relation is naturally produced by these conditions. The overall mass-metallicity relation Z(m{sub star}) directly provides the fraction f{sub star}(m{sub star}) of incoming baryons that are being transformed into stars. The observed Z(m{sub star}) relation of Sloan Digital Sky Survey (SDSS) galaxies implies a strong dependence of stellar mass on halo mass that reconciles the different faint-end slopes of the stellar and halo mass

  19. Low-mass galaxy assembly in simulations: regulation of early star formation by radiation from massive stars

    CERN Document Server

    Trujillo-Gomez, Sebastian; Colin, Pedro; Ceverino, Daniel; Arraki, Kenza; Primack, Joel

    2013-01-01

    Despite recent success in forming realistic disc galaxies at redshift zero, simulations still form the bulk of their stars prematurely. We investigate the process of stellar mass assembly in low-mass simulated galaxies, a dwarf and a typical spiral, focusing on the effects of radiation from young stellar clusters. We employ a novel model of star formation in which stars form deterministically with a small efficiency per free-fall time, as observed in molecular clouds. Stellar feedback includes radiation pressure from massive stars and energy from supernova explosions and stellar winds. In galaxies with masses up to those of typical spirals, radiation efficiently suppresses star formation by dispersing and heating high density gas, mostly in the central regions, preventing the formation of a massive bulge. Once the galaxies reach this radiation-regulated growth regime, their global properties are robust to the specific choice of model parameters. Only when radiative feedback is included, do galaxies exhibit co...

  20. In site bioimaging of hydrogen sulfide uncovers its pivotal role in regulating nitric oxide-induced lateral root formation.

    Directory of Open Access Journals (Sweden)

    Yan-Jun Li

    Full Text Available Hydrogen sulfide (H2S is an important gasotransmitter in mammals. Despite physiological changes induced by exogenous H2S donor NaHS to plants, whether and how H2S works as a true cellular signal in plants need to be examined. A self-developed specific fluorescent probe (WSP-1 was applied to track endogenous H2S in tomato (Solanum lycopersicum roots in site. Bioimaging combined with pharmacological and biochemical approaches were used to investigate the cross-talk among H2S, nitric oxide (NO, and Ca(2+ in regulating lateral root formation. Endogenous H2S accumulation was clearly associated with primordium initiation and lateral root emergence. NO donor SNP stimulated the generation of endogenous H2S and the expression of the gene coding for the enzyme responsible for endogenous H2S synthesis. Scavenging H2S or inhibiting H2S synthesis partially blocked SNP-induced lateral root formation and the expression of lateral root-related genes. The stimulatory effect of SNP on Ca(2+ accumulation and CaM1 (calmodulin 1 expression could be abolished by inhibiting H2S synthesis. Ca(2+ chelator or Ca(2+ channel blocker attenuated NaHS-induced lateral root formation. Our study confirmed the role of H2S as a cellular signal in plants being a mediator between NO and Ca(2+ in regulating lateral root formation.

  1. Implementation of training programs in self-regulated learning strategies in Moodle format: results of a experience in higher education.

    Science.gov (United States)

    Núñez, José Carlos; Cerezo, Rebeca; Bernardo, Ana; Rosário, Pedro; Valle, Antonio; Fernández, Estrella; Suárez, Natalia

    2011-04-01

    This paper tests the efficacy of an intervention program in virtual format intended to train studying and self-regulation strategies in university students. The aim of this intervention is to promote a series of strategies which allow students to manage their learning processes in a more proficient and autonomous way. The program has been developed in Moodle format and hosted by the Virtual Campus of the University of Oviedo. The present study had a semi-experimental design, included an experimental group (n=167) and a control one (n=206), and used pretest and posttest measures (self-regulated learning strategies' declarative knowledge, self-regulated learning macro-strategy planning-execution-assessment, self-regulated learning strategies on text, surface and deep learning approaches, and academic achievement). Data suggest that the students enrolled in the training program, comparing with students in the control group, showed a significant improvement in their declarative knowledge, general and on text use of learning strategies, increased their deep approach to learning, decreased their use of a surface approach and, in what concerns to academic achievement, statistically significant differences have been found in favour of the experimental group. PMID:21504681

  2. Implementation of training programs in self-regulated learning strategies in Moodle format: results of a experience in higher education.

    Science.gov (United States)

    Núñez, José Carlos; Cerezo, Rebeca; Bernardo, Ana; Rosário, Pedro; Valle, Antonio; Fernández, Estrella; Suárez, Natalia

    2011-04-01

    This paper tests the efficacy of an intervention program in virtual format intended to train studying and self-regulation strategies in university students. The aim of this intervention is to promote a series of strategies which allow students to manage their learning processes in a more proficient and autonomous way. The program has been developed in Moodle format and hosted by the Virtual Campus of the University of Oviedo. The present study had a semi-experimental design, included an experimental group (n=167) and a control one (n=206), and used pretest and posttest measures (self-regulated learning strategies' declarative knowledge, self-regulated learning macro-strategy planning-execution-assessment, self-regulated learning strategies on text, surface and deep learning approaches, and academic achievement). Data suggest that the students enrolled in the training program, comparing with students in the control group, showed a significant improvement in their declarative knowledge, general and on text use of learning strategies, increased their deep approach to learning, decreased their use of a surface approach and, in what concerns to academic achievement, statistically significant differences have been found in favour of the experimental group.

  3. TCPs, WUSs, and WINDs: Families of transcription factors that regulate shoot meristem formation, stem cell maintenance, and somatic cell differentiation

    Directory of Open Access Journals (Sweden)

    Miho eIkeda

    2014-09-01

    Full Text Available In contrast to somatic mammalian cells, which cannot alter their fate, plant cells can dedifferentiate to form totipotent callus cells and regenerate a whole plant, following treatment with specific phytohormones. However, the regulatory mechanisms and key factors that control differentiation-dedifferentiation and cell totipotency have not been completely clarified in plants. Recently, several plant transcription factors that regulate meristem formation and dedifferentiation have been identified and include members of the TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP, WUSCHEL (WUS, and WOUND INDUCED DEDIFFERENTIATION (WIND1 families. WUS and WIND positively control plant cell totipotency, while TCP negatively controls it. Interestingly, TCP is a transcriptional activator that acts as a negative regulator of shoot meristem formation, and WUS is a transcriptional repressor that positively maintains totipotency of the stem cells of the shoot meristem. We describe here the functions of TCP, WUS and WIND transcription factors in the regulation of differentiation-dedifferentiation by positive and negative transcriptional regulators.

  4. Shoot bending promotes flower bud formation by miRNA-mediated regulation in apple (Malus domestica Borkh.).

    Science.gov (United States)

    Xing, Libo; Zhang, Dong; Zhao, Caiping; Li, Youmei; Ma, Juanjuan; An, Na; Han, Mingyu

    2016-02-01

    Flower induction in apple (Malus domestica Borkh.) trees plays an important life cycle role, but young trees produce fewer and inferior quality flower buds. Therefore, shoot bending has become an important cultural practice, significantly promoting the capacity to develop more flower buds during the growing seasons. Additionally, microRNAs (miRNAs) play essential roles in plant growth, flower induction and stress responses. In this study, we identified miRNAs potentially involved in the regulation of bud growth, and flower induction and development, as well as in the response to shoot bending. Of the 195 miRNAs identified, 137 were novel miRNAs. The miRNA expression profiles revealed that the expression levels of 68 and 27 known miRNAs were down-regulated and up-regulated, respectively, in response to shoot bending, and that the 31 differentially expressed novel miRNAs between them formed five major clusters. Additionally, a complex regulatory network associated with auxin, cytokinin, abscisic acid (ABA) and gibberellic acid (GA) plays important roles in cell division, bud growth and flower induction, in which related miRNAs and targets mediated regulation. Among them, miR396, 160, 393, and their targets associated with AUX, miR159, 319, 164, and their targets associated with ABA and GA, and flowering-related miRNAs and genes, regulate bud growth and flower bud formation in response to shoot bending. Meanwhile, the flowering genes had significantly higher expression levels during shoot bending, suggesting that they are involved in this regulatory process. This study provides a framework for the future analysis of miRNAs associated with multiple hormones and their roles in the regulation of bud growth, and flower induction and formation in response to shoot bending in apple trees.

  5. GALAXY FORMATION WITH SELF-CONSISTENTLY MODELED STARS AND MASSIVE BLACK HOLES. I. FEEDBACK-REGULATED STAR FORMATION AND BLACK HOLE GROWTH

    International Nuclear Information System (INIS)

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 1011 Msun galactic halo and its 105 Msun embedded MBH at redshift 3 in a cosmological ΛCDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 106 K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

  6. Galaxy Formation with Self-Consistently Modeled Stars and Massive Black Holes. I: Feedback-Regulated Star Formation and Black Hole Growth

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-hoon; Wise, John H.; /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Princeton U., Astrophys. Sci. Dept.; Alvarez, Marcelo A.; /Canadian Inst. Theor. Astrophys.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2011-11-04

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 10{sup 11} M {circle_dot} galactic halo and its 10{sup 5} {circle_dot} M embedded MBH at redshift 3 in a cosmological CDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 10{sup 6} K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

  7. A putative ABC transporter is involved in negative regulation of biofilm formation by Listeria monocytogenes

    DEFF Research Database (Denmark)

    Zhu, Xinna; Long, Fei; Chen, Yonghui;

    2008-01-01

    Listeria monocytogenes may persist for long periods in food processing environments. In some instances, this may be due to aggregation or biofilm formation. To investigate the mechanism controlling biofilm formation in the food-borne pathogen L. monocytogenes, we characterized LM-49, a mutant...... with enhanced ability of biofilm-formation generated via transposon Tn917 mutagenesis of L. monocytogenes 4b G. In this mutant, a Tn917 insertion has disrupted the coding region of the gene encoding a putative ATP binding cassette (ABC) transporter permease identical to Lmof2365_1771 (a putative ABC...... the same amount of biofilm biomass as the wild-type strain. Furthermore, transcription of the downstream lm.G_1770 was not influenced by the upstream Tn917 insertion, and the presence of Tn917 has no effect on biofilm formation. These results suggest that lm.G_1771 was solely responsible for the negative...

  8. A novel genetic mechanism regulates dorsolateral hinge-point formation during zebrafish cranial neurulation

    OpenAIRE

    Nyholm, Molly K.; Abdelilah-Seyfried, Salim; Grinblat, Yevgenya

    2009-01-01

    During neurulation, vertebrate embryos form a neural tube (NT), the rudiment of the central nervous system. In mammals and birds, a key step in cranial NT morphogenesis is dorsolateral hinge-point (DLHP) bending, which requires an apical actomyosin network. The mechanism of DLHP formation is poorly understood, although several essential genes have been identified, among them Zic2, which encodes a zinc-finger transcription factor. We found that DLHP formation in the zeb...

  9. Nephron proximal tubule patterning and corpuscles of Stannius formation are regulated by the sim1a transcription factor and retinoic acid in zebrafish.

    Science.gov (United States)

    Cheng, Christina N; Wingert, Rebecca A

    2015-03-01

    The mechanisms that establish nephron segments are poorly understood. The zebrafish embryonic kidney, or pronephros, is a simplified yet conserved genetic model to study this renal development process because its nephrons contain segments akin to other vertebrates, including the proximal convoluted and straight tubules (PCT, PST). The zebrafish pronephros is also associated with the corpuscles of Stannius (CS), endocrine glands that regulate calcium and phosphate homeostasis, but whose ontogeny from renal progenitors is largely mysterious. Initial patterning of zebrafish renal progenitors in the intermediate mesoderm (IM) involves the formation of rostral and caudal domains, the former being reliant on retinoic acid (RA) signaling, and the latter being repressed by elevated RA levels. Here, using expression profiling to gain new insights into nephrogenesis, we discovered that the gene single minded family bHLH transcription factor 1a (sim1a) is dynamically expressed in the renal progenitors-first marking the caudal domain, then becoming restricted to the proximal segments, and finally exhibiting specific CS expression. In loss of function studies, sim1a knockdown expanded the PCT and abrogated both the PST and CS populations. Conversely, overexpression of sim1a modestly expanded the PST and CS, while it reduced the PCT. These results show that sim1a activity is necessary and partially sufficient to induce PST and CS fates, and suggest that sim1a may inhibit PCT fate and/or negotiate the PCT/PST boundary. Interestingly, the sim1a expression domain in renal progenitors is responsive to altered levels of RA, suggesting that RA regulates sim1a, directly or indirectly, during nephrogenesis. sim1a deficient embryos treated with exogenous RA formed nephrons that were predominantly composed of PCT segments, but lacked the enlarged PST observed in RA treated wild-types, indicating that RA is not sufficient to rescue the PST in the absence of sim1a expression. Alternately

  10. THE FORMATION OF ENTS ADAPTIVE REACTIONS DEPENDING ON THE TYPE OF PSYCHO-VEGETATIVE REGULATION

    OpenAIRE

    E. M. Kazin

    2014-01-01

    The purpose of the students (12 to 15 years old) examination was to identify the integrative criteria of assessing the nature of the functional relationships between the parameters of the psychosocial and physiological adaptation of students, depending on age, individual-typological peculiarities of vegetative regulation, personal potential at different stages of school education.The study of the characteristics of vegetative regulation of the cardiovascular system was made with a help of an ...

  11. IL-33 inhibits RANKL-induced osteoclast formation through the regulation of Blimp-1 and IRF-8 expression

    Energy Technology Data Exchange (ETDEWEB)

    Kiyomiya, Hiroyasu [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Division of Oral and Maxillofacial Surgery, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Ariyoshi, Wataru; Okinaga, Toshinori [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Kaneuji, Takeshi [Division of Oral Medicine, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Mitsugi, Sho [Division of Oral and Maxillofacial Surgery, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Sakurai, Takuma [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Division of Oral and Maxillofacial Surgery, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Habu, Manabu [Division of Oral and Maxillofacial Surgery, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Yoshioka, Izumi [Division of Oral Medicine, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); Tominaga, Kazuhiro [Division of Oral and Maxillofacial Surgery, Department of Science of Physical Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580 (Japan); and others

    2015-05-01

    Interleukin (IL)-33 is a recently discovered proinflammatory cytokine that belongs to the IL-1 family. Several studies have reported that IL-33 inhibits osteoclast differentiation. However, the mechanism of IL-33 regulation of osteoclastogenesis remains unclear. In the present study, we examined the effect of IL-33 on osteoclast formation in vitro. IL-33 suppressed osteoclast formation in both mouse bone marrow cells and monocyte/macrophage cell line RAW264.7 cells induced by receptor activator of NF-κB ligand (RANKL) and/or macrophage stimulating factor (M-CSF). IL-33 also inhibited the expression of RANKL-induced nuclear factor of activated T-cell cytoplasmic 1 (NFATc1), thereby decreasing the expression of osteoclastogenesis-related marker genes, including Cathepsin K, Osteoclast stimulatory transmembrane protein (Oc-stamp) and Tartrate-resistant acid phosphatase (Trap). Blockage of IL-33-ST2 binding suppressed the IL-33-mediated inhibition of NFATc1. RANKL-induced B-lymphocyte-induced maturation protein-1 (Blimp-1) expression was also suppressed by IL-33, which was followed by the stimulation of anti-osteoclastic genes such as interferon regulatory factor-8 (IRF-8). These results suggest that IL-33-ST2 interactions down-regulate both RANKL-induced NFATc1 activation and osteoclast differentiation via the regulation of Blimp-1 and IRF-8 expression. - Highlights: • IL-33 inhibits RANKL-induced osteoclast formation. • IL-33 has inhibitory effect on the RANKL-induced NFATc1 expression. • IL-33-induced NFATc1 suppression depends on the regulation of Blimp-1 and IRF-8.

  12. Endothelial-Specific EphA4 Negatively Regulates Native Pial Collateral Formation and Re-Perfusion following Hindlimb Ischemia

    Science.gov (United States)

    Okyere, Benjamin; Giridhar, Kaavya; Hazy, Amanda; Chen, Miao; Keimig, David; Bielitz, Robert C.; Xie, Hehuang; He, Jia-Qiang; Huckle, William R.; Theus, Michelle H.

    2016-01-01

    Leptomeningeal anastomoses play a critical role in regulating vascular re-perfusion following obstruction, however, the mechanisms regulating their development remains under investingation. Our current findings indicate that EphA4 receptor is a novel negative regulator of collaterogenesis. We demonstrate that EphA4 is highly expressed on pial arteriole collaterals at post-natal day (P) 1 and 7, then significantly reduced by P21. Endothelial cell (EC)-specific loss of EphA4, EphA4f/f/Tie2::Cre (KO), resulted in an increase in the density but not diameter of pial collaterals compared to WT mice. ECs isolated from KO mice displayed a 3-fold increase in proliferation, enhanced migration, tube formation and elevated levels of phospho(p)-Akt compared to WT ECs. Attenuating p-Akt, using LY294002, reduced the proliferative and migration effects in the KO ECs. RNAseq analysis also revealed altered expression patterns for genes that regulate cell proliferation, vascular development, extracellular matrix and immune-mediate responses, namely MCP-1, MMP2 and angiopoietin-1. Lastly, we show that induction of hindlimb ischemia resulted in accelerated re-perfusion, collateral remodeling and reduced tissue necrosis in the absence of EC-specific EphA4 compared to WT mice. These findings demonstrate a novel role for EphA4 in the early development of the pial collateral network and suggests a role in regulating vascular remodeling after obstruction. PMID:27467069

  13. The transcriptional regulator c2h2 accelerates mushroom formation in Agaricus bisporus.

    Science.gov (United States)

    Pelkmans, Jordi F; Vos, Aurin M; Scholtmeijer, Karin; Hendrix, Ed; Baars, Johan J P; Gehrmann, Thies; Reinders, Marcel J T; Lugones, Luis G; Wösten, Han A B

    2016-08-01

    The Cys2His2 zinc finger protein gene c2h2 of Schizophyllum commune is involved in mushroom formation. Its inactivation results in a strain that is arrested at the stage of aggregate formation. In this study, the c2h2 orthologue of Agaricus bisporus was over-expressed in this white button mushroom forming basidiomycete using Agrobacterium-mediated transformation. Morphology, cap expansion rate, and total number and biomass of mushrooms were not affected by over-expression of c2h2. However, yield per day of the c2h2 over-expression strains peaked 1 day earlier. These data and expression analysis indicate that C2H2 impacts timing of mushroom formation at an early stage of development, making its encoding gene a target for breeding of commercial mushroom strains. PMID:27207144

  14. 'Rod and ring' formation from IMP dehydrogenase is regulated through the one-carbon metabolic pathway.

    Science.gov (United States)

    Calise, S John; Purich, Daniel L; Nguyen, Thuy; Saleem, Dania A; Krueger, Claire; Yin, Joyce D; Chan, Edward K L

    2016-08-01

    'Rods and rings' (RRs) are conserved, non-membrane-bound intracellular polymeric structures composed, in part, of inosine monophosphate dehydrogenase (IMPDH), a key enzyme leading to GMP and GTP biosynthesis. RR formation is induced by IMPDH inhibitors as well as glutamine deprivation. They also form upon treatment of cells with glutamine synthetase inhibitors. We now report that depriving cells of serine and glycine promotes RR formation, and we have traced these effects to dihydrofolate reductase (DHFR) and serine hydroxymethyltransferase-2 (SHMT2), pivotal enzymes in one-carbon metabolism and nucleotide biosynthesis. RR assembly is likewise induced upon DHFR inhibition by methotrexate or aminopterin as well as siRNA-mediated knockdown of DHFR or SHMT2. Because RR assembly occurs when guanine nucleotide biosynthesis is inhibited, and because RRs rapidly disassemble after the addition of guanine nucleotide precursors, RR formation might be an adaptive homeostatic mechanism, allowing IMPDH to sense changes in the one-carbon folate pathway. PMID:27343244

  15. Clathrin-Mediated Auxin Efflux and Maxima Regulate Hypocotyl Hook Formation and Light-Stimulated Hook Opening in Arabidopsis.

    Science.gov (United States)

    Yu, Qinqin; Zhang, Ying; Wang, Juan; Yan, Xu; Wang, Chao; Xu, Jian; Pan, Jianwei

    2016-01-01

    The establishment of auxin maxima by PIN-FORMED 3 (PIN3)- and AUXIN RESISTANT 1/LIKE AUX1 (LAX) 3 (AUX1/LAX3)-mediated auxin transport is essential for hook formation in Arabidopsis hypocotyls. Until now, however, the underlying regulatory mechanism has remained poorly understood. Here, we show that loss of function of clathrin light chain CLC2 and CLC3 genes enhanced auxin maxima and thereby hook curvature, alleviated the inhibitory effect of auxin overproduction on auxin maxima and hook curvature, and delayed blue light-stimulated auxin maxima reduction and hook opening. Moreover, pharmacological experiments revealed that auxin maxima formation and hook curvature in clc2 clc3 were sensitive to auxin efflux inhibitors 1-naphthylphthalamic acid and 2,3,5-triiodobenzoic acid but not to the auxin influx inhibitor 1-naphthoxyacetic acid. Live-cell imaging analysis further uncovered that loss of CLC2 and CLC3 function impaired PIN3 endocytosis and promoted its lateralization in the cortical cells but did not affect AUX1 localization. Taken together, these results suggest that clathrin regulates auxin maxima and thereby hook formation through modulating PIN3 localization and auxin efflux, providing a novel mechanism that integrates developmental signals and environmental cues to regulate plant skotomorphogenesis and photomorphogenesis.

  16. SWAP-70 controls formation of the splenic marginal zone through regulating T1B-cell differentiation.

    Science.gov (United States)

    Chopin, Michaël; Quemeneur, Laurence; Ripich, Tatsiana; Jessberger, Rolf

    2010-12-01

    T1 and T2 transitional B cells are precursors for marginal zone B cells (MZB), which surround splenic follicles. MZB are essential for marginal zone formation, are central to the innate immune response, and contribute to adaptive immunity. Differentiation, migration, and homing of MZB and their precursors remain to be fully understood. We show that SWAP-70, a RhoGTPase-interacting and F-actin-binding protein with functions in cell polarization, migration, and adhesion regulates MZB development and marginal zone formation. The percentage of MZB in spleen of Swap70(-/-) mice was reduced to about one-third of that found in WT mice. Swap70(-/-) T1 cells accumulated in integrin ligand(high) regions of the splenic red pulp and failed to efficiently develop into T2 cells. Adoptive transfer and mixed BM chimera experiments demonstrated this to be a B-cell intrinsic phenotype. T-cell-independent antibody production was not impaired, however, and thus suggests that this process does not require correct homing of MZB precursors. B-cell adhesion through α(L)β(2) and α(4)β(1) integrins was hyper-activated in vitro and on tissue sections, and S1P-stimulated chemokinesis of MZB was reduced in the absence of SWAP-70. Thus, SWAP-70 acts as a regulator of the adhesion process, particularly important for differentiation control of B-cell precursors and their contribution to splenic tissue formation.

  17. Involvement of cyclin K posttranscriptional regulation in the formation of Artemia diapause cysts.

    Directory of Open Access Journals (Sweden)

    Yang Zhao

    Full Text Available BACKGROUND: Artemia eggs tend to develop ovoviviparously to yield nauplius larvae in good rearing conditions; while under adverse situations, they tend to develop oviparously and encysted diapause embryos are formed instead. However, the intrinsic mechanisms regulating this process are not well understood. PRINCIPAL FINDING: This study has characterized the function of cyclin K, a regulatory subunit of the positive transcription elongation factor b (P-TEFb in the two different developmental pathways of Artemia. In the diapause-destined embryo, Western blots showed that the cyclin K protein was down-regulated as the embryo entered dormancy and reverted to relatively high levels of expression once development resumed, consistent with the fluctuations in phosphorylation of position 2 serines (Ser2 in the C-terminal domain (CTD of the largest subunit (Rpb1 of RNA polymerase II (RNAP II. Interestingly, the cyclin K transcript levels remained constant during this process. In vitro translation data indicated that the template activity of cyclin K mRNA stored in the postdiapause cyst was repressed. In addition, in vivo knockdown of cyclin K in developing embryos by RNA interference eliminated phosphorylation of the CTD Ser2 of RNAP II and induced apoptosis by inhibiting the extracellular signal-regulated kinase (ERK survival signaling pathway. CONCLUSIONS/SIGNIFICANCE: Taken together, these findings reveal a role for cyclin K in regulating RNAP II activity during diapause embryo development, which involves the post-transcriptional regulation of cyclin K. In addition, a further role was identified for cyclin K in regulating the control of cell survival during embryogenesis through ERK signaling pathways.

  18. AMP-activated protein kinase (AMPK) activation regulates in vitro bone formation and bone mass

    OpenAIRE

    Shah, M; Kola, B; Bataveljic, A.; Arnett, T. R.; Viollet, B.; Saxon, L.; Korbonits, M.; C. Chenu

    2010-01-01

    Adenosine 5′-monophosphate-activated protein kinase (AMPK), a regulator of energy homeostasis, has a central role in mediating the appetite-modulating and metabolic effects of many hormones and antidiabetic drugs metformin and glitazones. The objective of this study was to determine if AMPK can be activated in osteoblasts by known AMPK modulators and if AMPK activity is involved in osteoblast function in vitro and regulation of bone mass in vivo. ROS 17/2.8 rat osteoblast-like cells were cult...

  19. Regulation of Amidase Formation in Mutants from Pseudomonas aeruginosa PAO Lacking Glutamine Synthetase Activity

    NARCIS (Netherlands)

    Janssen, Dick B.; Herst, Patricia M.; Joosten, Han M.L.J.; Drift, Chris van der

    1982-01-01

    The formation of amidase was studied in mutants from Pseudomonas aeruginosa PAO lacking glutamine synthetase activity. It appeared that catabolite repression of amidase synthesis by succinate was partially relieved when cellular growth was limited by glutamine. Under these conditions, a correlation

  20. The self regulating star formation of gas rich dwarf galaxies in quiescent phase

    CERN Document Server

    Kobayashi, M A R; Kobayashi, Masakazu A.R.; Kamaya, Hideyuki

    2004-01-01

    The expected episodic or intermittent star formation histories (SFHs) of gas rich dwarf irregular galaxies (dIrrs) are the longstanding puzzles to understand their whole evolutional history. Solving this puzzle, we should grasp what physical mechanism causes the quiescent phase of star formation under the very gas rich condition after the first starburst phase. We consider that this quiescent phase is kept by lack of H2, which can be important coolant to generate the next generation of stars in the low-metal environment like dIrrs. Furthermore, in dIrrs, H2 formation through gas-phase reactions may dominate the one on dust-grain surfaces because their interstellar medium (ISM) are very plentiful and the typical dust-to-gas ratio of dIrrs (D_dIrrs = 1.31 x 10^-2 D_MW, where D_MW is its value for the local ISM) is on the same order with a critical value D_cr ~ 10^-2 D_MW. We show that the lack of H2 is mainly led by H- destruction when gas-phase H2 formation dominates since H- is important intermediary of gas-p...

  1. Transcriptomic analysis reveals ethylene as stimulator and auxin as regulator of adventitious root formation in petunia cuttings

    Directory of Open Access Journals (Sweden)

    Uwe eDruege

    2014-09-01

    Full Text Available Adventitious root (AR formation in the stem base of cuttings is the basis for propagation of many plant species and petunia is used as model to study this developmental process. Following AR formation from 2 to 192 hours after excision (hpe of cuttings, transcriptome analysis by microarray revealed a change of the character of the rooting zone from stem base to root identity. The greatest shift in the number of differentially expressed genes was observed between 24 and 72 hpe, when the categories storage, mineral nutrient acquisition, anti-oxidative and secondary metabolism, and biotic stimuli showed a notable high number of induced genes. Analyses of phytohormone-related genes disclosed multifaceted changes of the auxin transport system, auxin conjugation and the auxin signal perception machinery indicating a reduction in auxin sensitivity and phase-specific responses of particular auxin-regulated genes. Genes involved in ethylene biosynthesis and action showed a more uniform pattern as a high number of respective genes were generally induced during the whole process of AR formation. The important role of ethylene for stimulating AR formation was demonstrated by the application of inhibitors of ethylene biosynthesis and perception as well as of the precursor aminocyclopropane-1-carboxylic acid, all changing the number and length of AR. A model is proposed showing the putative role of polar auxin transport and resulting auxin accumulation in initiation of subsequent changes in auxin homeostasis and signal perception with a particular role of Aux/IAA expression. These changes might in turn guide the entrance into the different phases of AR formation. Ethylene biosynthesis, which is stimulated by wounding and does probably also respond to other stresses and auxin, acts as important stimulator of AR formation probably via the expression of ethylene responsive transcription factor genes, whereas the timing of different phases seems to be controlled

  2. The redox-sensing regulator Rex modulates central carbon metabolism, stress tolerance response and biofilm formation by Streptococcus mutans.

    Directory of Open Access Journals (Sweden)

    Jacob P Bitoun

    Full Text Available The Rex repressor has been implicated in regulation of central carbon and energy metabolism in gram-positive bacteria. We have previously shown that Streptococcus mutans, the primary causative agent of dental caries, alters its transcriptome upon Rex-deficiency and renders S. mutans to have increased susceptibility to oxidative stress, aberrations in glucan production, and poor biofilm formation. In this study, we showed that rex in S. mutans is co-transcribed as an operon with downstream guaA, encoding a putative glutamine amidotransferase. Electrophoretic mobility shift assays showed that recombinant Rex bound promoters of target genes avidly and specifically, including those down-regulated in response to Rex-deficiency, and that the ability of recombinant Rex to bind to selected promoters was modulated by NADH and NAD(+. Results suggest that Rex in S. mutans can function as an activator in response to intracellular NADH/NAD(+ level, although the exact binding site for activator Rex remains unclear. Consistent with a role in oxidative stress tolerance, hydrogen peroxide challenge assays showed that the Rex-deficient mutant, TW239, and the Rex/GuaA double mutant, JB314, were more susceptible to hydrogen peroxide killing than the wildtype, UA159. Relative to UA159, JB314 displayed major defects in biofilm formation, with a decrease of more than 50-fold in biomass after 48-hours. Collectively, these results further suggest that Rex in S. mutans regulates fermentation pathways, oxidative stress tolerance, and biofilm formation in response to intracellular NADH/NAD(+ level. Current effort is being directed to further investigation of the role of GuaA in S. mutans cellular physiology.

  3. Plant stanols induce intestinal tumor formation by up-regulating Wnt and EGFR signaling in Apc Min mice.

    Science.gov (United States)

    Marttinen, Maija; Päivärinta, Essi; Storvik, Markus; Huikko, Laura; Luoma-Halkola, Heli; Piironen, Vieno; Pajari, Anne-Maria; Mutanen, Marja

    2013-01-01

    The rate of APC mutations in the intestine increases in middle-age. At the same period of life, plant sterol and stanol enriched functional foods are introduced to diet to lower blood cholesterol. This study examined the effect of plant stanol enriched diet on intestinal adenoma formation in the Apc(Min) mouse. Apc(Min) mice were fed 0.8% plant stanol diet or control diet for nine weeks. Cholesterol, plant sterols and plant stanols were analyzed from the caecum content and the intestinal mucosa. Levels of β-catenin, cyclin D1, epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase 1/2 (ERK1/2) were measured from the intestinal mucosa by Western blotting. Gene expression was determined from the intestinal mucosa using Affymetrix and the data were analyzed for enriched categories and pathways. Plant stanols induced adenoma formation in the small intestine, however, the adenoma size was not affected. We saw increased levels of nuclear β-catenin, phosphorylated β-catenin (Ser675 and Ser552), nuclear cyclin D1, total and phosphorylated EGFR and phosphorylated ERK1/2 in the intestinal mucosa after plant stanol feeding. The Affymetrix data demonstrate that several enzymes of cholesterol synthesis pathway were up-regulated, although the cholesterol level in the intestinal mucosa was not altered. We show that plant stanols induce adenoma formation by activating Wnt and EGFR signaling. EGFR signaling seems to have promoted β-catenin phosphorylation and its translocation into the nucleus, where the expression of cyclin D1 was increased. Up-regulated cholesterol synthesis may partly explain the increased EGFR signaling in the plant stanol-fed mice.

  4. Flower-bud formation in explants of photoperiodic and day-neutral Nicotiana biotypes and its bearing on the regulation of flower formation

    Energy Technology Data Exchange (ETDEWEB)

    Rajeevan, M.S.; Lang, A. (Michigan State Univ., East Lansing (United States))

    1993-05-15

    The capacity to form flower buds in thin-layer explants was studied in Nicotiana of several species, cultivars, and lines of differing in their response to photoperiod. This capacity was found in all biotypes examined and could extend into sepals and corolla. It varied depending on genotype, source tissue and its developmental state, and composition of the culture medium, particularly the levels of glucose, auxin, and cytokinin. It was greatest in the two day-neutral plants examined, Samsun tobacco and Nicotiana rustica, where it extended from the inflorescence region down the vegetative stem, in a basipetally decreasing gradient; it was least in the two qualitative photoperiodic plants studied, the long-day plant Nicotiana silvestris and the short-day plant Maryland Mammoth tobacco, the quantitative long-day plant Nicotiana alata and the quantitative short-day plant Nicotiana otophora line 38-G-81, where it was limited to the pedicels (and, in some cases, the sepals). Regardless of the photoperiodic response of the source plants, the response was the same in explants cultured under long and short days. The capacity to form flow buds in explants is present in all Nicotiana biotypes studied supports the idea that it is regulated by the same mechanism(s), regardless of the plant's photoperiodic character. However, flower formation in the explants is not identical with de novo flower formation in a hitherto vegetative plant: it is rather the expression of a floral state already established in the plant, although it can vary widely in extent and spatial distribution. Culture conditions that permit flower-bud formation in an explant are conditions that maintain the floral state and encourage its expression; conditions under which no flower buds are formed reduce this state and/or prevent its expression. 14 refs., 5 figs., 3 tabs.

  5. MADS-Box Transcription Factor VdMcm1 Regulates Conidiation, Microsclerotia Formation, Pathogenicity, and Secondary Metabolism of Verticillium dahliae

    Science.gov (United States)

    Xiong, Dianguang; Wang, Yonglin; Tian, Longyan; Tian, Chengming

    2016-01-01

    Verticillium dahliae, a notorious phytopathogenic fungus, causes vascular wilt diseases in many plant species resulting in devastating yield losses worldwide. Due to its ability to colonize plant xylem and form microsclerotia, V. dahliae is highly persistent and difficult to control. In this study, we show that the MADS-box transcription factor VdMcm1 is a key regulator of conidiation, microsclerotia formation, virulence, and secondary metabolism of V. dahliae. In addition, our findings suggest that VdMcm1 is involved in cell wall integrity. Finally, comparative RNA-Seq analysis reveals 823 significantly downregulated genes in the VdMcm1 deletion mutant, with diverse biological functions in transcriptional regulation, plant infection, cell adhesion, secondary metabolism, transmembrane transport activity, and cell secretion. When taken together, these data suggest that VdMcm1 performs pleiotropic functions in V. dahliae. PMID:27536281

  6. MADS-Box Transcription Factor VdMcm1 Regulates Conidiation, Microsclerotia Formation, Pathogenicity, and Secondary Metabolism of Verticillium dahliae.

    Science.gov (United States)

    Xiong, Dianguang; Wang, Yonglin; Tian, Longyan; Tian, Chengming

    2016-01-01

    Verticillium dahliae, a notorious phytopathogenic fungus, causes vascular wilt diseases in many plant species resulting in devastating yield losses worldwide. Due to its ability to colonize plant xylem and form microsclerotia, V. dahliae is highly persistent and difficult to control. In this study, we show that the MADS-box transcription factor VdMcm1 is a key regulator of conidiation, microsclerotia formation, virulence, and secondary metabolism of V. dahliae. In addition, our findings suggest that VdMcm1 is involved in cell wall integrity. Finally, comparative RNA-Seq analysis reveals 823 significantly downregulated genes in the VdMcm1 deletion mutant, with diverse biological functions in transcriptional regulation, plant infection, cell adhesion, secondary metabolism, transmembrane transport activity, and cell secretion. When taken together, these data suggest that VdMcm1 performs pleiotropic functions in V. dahliae. PMID:27536281

  7. The jaw of the worm: GTPase-activating protein EAT-17 regulates grinder formation in Caenorhabditis elegans.

    Science.gov (United States)

    Straud, Sarah; Lee, Inhwan; Song, Bomi; Avery, Leon; You, Young-Jai

    2013-09-01

    Constitutive transport of cellular materials is essential for cell survival. Although multiple small GTPase Rab proteins are required for the process, few regulators of Rabs are known. Here we report that EAT-17, a novel GTPase-activating protein (GAP), regulates RAB-6.2 function in grinder formation in Caenorhabditis elegans. We identified EAT-17 as a novel RabGAP that interacts with RAB-6.2, a protein that presumably regulates vesicle trafficking between Golgi, the endoplasmic reticulum, and plasma membrane to form a functional grinder. EAT-17 has a canonical GAP domain that is critical for its function. RNA interference against 25 confirmed and/or predicted RABs in C. elegans shows that RNAi against rab-6.2 produces a phenotype identical to eat-17. A directed yeast two-hybrid screen using EAT-17 as bait and each of the 25 RAB proteins as prey identifies RAB-6.2 as the interacting partner of EAT-17, confirming that RAB-6.2 is a specific substrate of EAT-17. Additionally, deletion mutants of rab-6.2 show grinder defects identical to those of eat-17 loss-of-function mutants, and both RAB-6.2 and EAT-17 are expressed in the terminal bulb of the pharynx where the grinder is located. Collectively, these results suggest that EAT-17 is a specific GTPase-activating protein for RAB-6.2. Based on the conserved function of Rab6 in vesicular transport, we propose that EAT-17 regulates the turnover rate of RAB-6.2 activity in cargo trafficking for grinder formation.

  8. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    in the period of post-acquisition when their organization is being integrated into the acquiring MNC. The paper contributes to the literature on boundary spanning in three ways: First, by illustrating that boundary spanning is performed by numerous organizational actors in a variety of positions in MNCs......, inclusively by locals in subsidiaries. Second, by showing that boundary spanning is ‘situated’ in the sense that its result depends on the kind of knowledge to be transmitted and the attitude of the receivers. A third contribution is methodological. The study illustrates that combining bottom-up grounded...

  9. Phosphate Interacts With PTHrP to Regulate Endochondral Bone Formation

    OpenAIRE

    Liu, Eva S.; Zalutskaya, Alena; Chae, Byongsoo Timothy; Zhu, Eric D.; Gori, Francesca; Demay, Marie B.

    2014-01-01

    Phosphate and parathyroid hormone related peptide (PTHrP) are required for normal growth plate maturation. Hypophosphatemia impairs hypertrophic chondrocyte apoptosis leading to rachitic expansion of the growth plate; however, the effect of phosphate restriction on chondrocyte differentiation during endochondral bone formation has not been examined. Investigations were, therefore, undertaken to address whether phosphate restriction alters the maturation of embryonic d15.5 murine metatarsal el...

  10. Dust-regulated galaxy formation and evolution:A new chemodynamical model with live dust particles

    CERN Document Server

    Bekki, Kenji

    2015-01-01

    Interstellar dust plays decisive roles in the conversion of neutral to molecular hydrogen (H_2), the thermodynamical evolution of interstellar medium (ISM), and the modification of spectral energy distributions (SEDs) of galaxies. These important roles of dust have not been self-consistently included in previous numerical simulations of galaxy formation and evolution. We have therefore developed a new model by which one can investigate whether and how galaxy formation and evolution can be influenced by dust-related physical processes such as photo-electric heating, H_2 formation on dust, and stellar radiation pressure on dust in detail. A novel point of the model is that different dust species in a galaxy are represented by `live dust' particles (i.e., not test particles). Therefore, dust particles in a galaxy not only interact gravitationally with all four components of the galaxy (i.e., dark matter, stars, gas, and dust) but also are grown and destroyed through physical processes of ISM. First we describe a...

  11. The formation, function and regulation of amyloids: insights from structural biology.

    Science.gov (United States)

    Landreh, M; Sawaya, M R; Hipp, M S; Eisenberg, D S; Wüthrich, K; Hartl, F U

    2016-08-01

    Amyloid diseases are characterized by the accumulation of insoluble, β-strand-rich aggregates. The underlying structural conversions are closely associated with cellular toxicity, but can also drive the formation of functional protein assemblies. In recent years, studies in the field of structural studies have revealed astonishing insights into the origins, mechanisms and implications of amyloid formation. Notably, high-resolution crystal structures of peptides in amyloid-like fibrils and prefibrillar oligomers have become available despite their challenging chemical nature. Nuclear magnetic resonance spectroscopy has revealed that dynamic local polymorphisms in the benign form of the prion protein affect the transformation into amyloid fibrils and the transmissibility of prion diseases. Studies of the structures and interactions of chaperone proteins help us to understand how the cellular proteostasis network is able to recognize different stages of aberrant protein folding and prevent aggregation. In this review, we will focus on recent developments that connect the different aspects of amyloid biology and discuss how understanding the process of amyloid formation and the associated defence mechanisms can reveal targets for pharmacological intervention that may become the first steps towards clinically viable treatment strategies. PMID:27237473

  12. Operon Formation is Driven by Co-Regulation and Not by Horizontal Gene Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Price, Morgan N.; Huang, Katherine H.; Arkin, Adam P.; Alm, Eric J.

    2005-04-12

    Although operons are often subject to horizontal gene transfer (HGT), non-HGT genes are particularly likely to be in operons. To resolve this apparent discrepancy and to determine whether HGT is involved in operon formation, we examined the evolutionary history of the genes and operons in Escherichia coli K12. We show that genes that have homologs in distantly related bacteria but not in close relatives of E. coli (indicating HGTi) form new operons at about the same rates as native genes. Furthermore, genes in new operons are no more likely than other genes to have phylogenetic trees that are inconsistent with the species tree. In contrast, essential genes and ubiquitous genes without paralogs (genes believed to undergo HGT rarely) often form new operons. We conclude that HGT is not associated with operon formation, but instead promotes the prevalence of pre-existing operons. To explain operon formation, we propose that new operons reduce the amount of regulatory information required to specify optimal expression patterns. Consistent with this hypothesis, operons have greater amounts of conserved regulatory sequences than do individually transcribed genes.

  13. Tsukushi modulates Xnr2, FGF and BMP signaling: regulation of Xenopus germ layer formation.

    Directory of Open Access Journals (Sweden)

    Samantha A Morris

    Full Text Available BACKGROUND: Cell-cell communication is essential in tissue patterning. In early amphibian development, mesoderm is formed in the blastula-stage embryo through inductive interactions in which vegetal cells act on overlying equatorial cells. Members of the TGF-beta family such as activin B, Vg1, derrière and Xenopus nodal-related proteins (Xnrs are candidate mesoderm inducing factors, with further activity to induce endoderm of the vegetal region. TGF-beta-like ligands, including BMP, are also responsible for patterning of germ layers. In addition, FGF signaling is essential for mesoderm formation whereas FGF signal inhibition has been implicated in endoderm induction. Clearly, several signaling pathways are coordinated to produce an appropriate developmental output; although intracellular crosstalk is known to integrate multiple pathways, relatively little is known about extracellular coordination. METHODOLOGY/PRINCIPAL FINDINGS: Here, we show that Xenopus Tsukushi (X-TSK, a member of the secreted small leucine rich repeat proteoglycan (SLRP family, is expressed in ectoderm, endoderm, and the organizer during early development. We have previously reported that X-TSK binds to and inhibits BMP signaling in cooperation with chordin. We now demonstrate two novel interactions: X-TSK binds to and inhibits signaling by FGF8b, in addition to binding to and enhancement of Xnr2 signaling. This signal integration by X-TSK at the extracellular level has an important role in germ layer formation and patterning. Vegetally localized X-TSK potentiates endoderm formation through coordination of BMP, FGF and Xnr2 signaling. In contrast, X-TSK inhibition of FGF-MAPK signaling blocks ventrolateral mesoderm formation, while BMP inhibition enhances organizer formation. These actions of X-TSK are reliant upon its expression in endoderm and dorsal mesoderm, with relative exclusion from ventrolateral mesoderm, in a pattern shaped by FGF signals. CONCLUSIONS

  14. Blowing off steam: Tuffisite formation as a regulator for lava dome eruptions

    Science.gov (United States)

    Kendrick, Jackie; Lavallée, Yan; Varley, Nick; Wadsworth, Fabian; Lamb, Oliver; Vasseur, Jérémie

    2016-04-01

    Tuffisites are veins of variably sintered, pyroclastic particles that form in conduits and lava domes as a result of localized fragmentation events during gas-and-ash explosions. Those observed in-situ on the active 2012 lava dome of Volcán de Colima range from voids with intra-clasts showing little movement and interpreted to be failure-nuclei, to sub-parallel lenses of sintered granular aggregate interpreted as fragmentation horizons, through to infilled fractures with evidence of viscous remobilization. All tuffisites show evidence of sintering. Further examination of the complex fracture-and-channel patterns reveals viscous backfill by surrounding magma, suggesting that lava fragmentation was followed by stress relaxation and continued viscous deformation as the tuffisites formed. The natural tuffisites are more permeable than the host andesite, and have a wide range of porosity and permeability compared to a narrower window for the host rock, and gauging from their significant distribution across the dome, we posit that the tuffisite veins may act as important outgassing pathways. To investigate tuffisite formation we crushed and sieved andesite from the lava dome and sintered it at magmatic temperatures for different times. We then assessed the healing and sealing ability by measuring porosity and permeability, showing that sintering reduces both over time. During sintering the porosity-permeability reduction occurs due to the formation of viscous necks between adjacent grains, a process described by the neck-formation model of Frenkel (1945). This process leads the granular starting material to a porosity-permeability regime anticipated for effusive lavas, and which describes the natural host lava as well as the most impervious of natural tuffisites. This suggests that tuffisite formation at Volcán de Colima constructed a permeable network that enabled gas to bleed passively from the magma. We postulate that this progressively reduced the lava dome

  15. Ras-Mek-Erk Signaling Regulates Nf1 Heterozygous Neointima Formation

    OpenAIRE

    Stansfield, Brian K.; Bessler, Waylan K.; Mali, Raghuveer; Mund, Julie A.; Downing, Brandon D.; Kapur, Reuben; Ingram, David A.

    2014-01-01

    Neurofibromatosis type 1 (NF1) results from mutations in the NF1 tumor-suppressor gene, which encodes neurofibromin, a negative regulator of diverse Ras signaling cascades. Arterial stenosis is a nonneoplastic manifestation of NF1 that predisposes some patients to debilitating morbidity and sudden death. Recent murine studies demonstrate that Nf1 heterozygosity (Nf1+/−) in monocytes/macrophages significantly enhances intimal proliferation after arterial injury. However, the downstream Ras eff...

  16. Pyk2 Regulates Megakaryocyte-Induced Increases in Osteoblast Number and Bone Formation

    OpenAIRE

    Cheng, Ying-Hua; Hooker, R. Adam; NGUYEN, Khanh; Gerard-O’Riley, Rita; Waning, David L.; Chitteti, Brahmananda R; Meijome, Tomas E.; Chua, Hui Lin; Plett, Artur P.; Orschell, Christie M.; Srour, Edward F.; Mayo, Lindsey D.; Pavalko, Fredrick M; Bruzzaniti, Angela; Kacena, Melissa A.

    2013-01-01

    Pre-clinical and clinical evidence from megakaryocyte (MK) related diseases suggest that MKs play a significant role in maintaining bone homeostasis. Findings from our laboratories reveal that MKs significantly increase osteoblast (OB) number through direct MK-OB contact and the activation of integrins. We therefore examined the role of Pyk2, a tyrosine kinase known to be regulated downstream of integrins, in the MK-mediated enhancement of OBs. When OBs were co-cultured with MKs, total Pyk2 l...

  17. Evolution-development congruence in pattern formation dynamics: Bifurcations in gene expression and regulation of networks structures.

    Science.gov (United States)

    Kohsokabe, Takahiro; Kaneko, Kunihiko

    2016-01-01

    Search for possible relationships between phylogeny and ontogeny is important in evolutionary-developmental biology. Here we uncover such relationships by numerical evolution and unveil their origin in terms of dynamical systems theory. By representing developmental dynamics of spatially located cells with gene expression dynamics with cell-to-cell interaction under external morphogen gradient, gene regulation networks are evolved under mutation and selection with the fitness to approach a prescribed spatial pattern of expressed genes. For most numerical evolution experiments, evolution of pattern over generations and development of pattern by an evolved network exhibit remarkable congruence. Both in the evolution and development pattern changes consist of several epochs where stripes are formed in a short time, while for other temporal regimes, pattern hardly changes. In evolution, these quasi-stationary regimes are generations needed to hit relevant mutations, while in development, they are due to some gene expression that varies slowly and controls the pattern change. The morphogenesis is regulated by combinations of feedback or feedforward regulations, where the upstream feedforward network reads the external morphogen gradient, and generates a pattern used as a boundary condition for the later patterns. The ordering from up to downstream is common in evolution and development, while the successive epochal changes in development and evolution are represented as common bifurcations in dynamical-systems theory, which lead to the evolution-development congruence. Mechanism of exceptional violation of the congruence is also unveiled. Our results provide a new look on developmental stages, punctuated equilibrium, developmental bottlenecks, and evolutionary acquisition of novelty in morphogenesis.

  18. Evolution-development congruence in pattern formation dynamics: Bifurcations in gene expression and regulation of networks structures.

    Science.gov (United States)

    Kohsokabe, Takahiro; Kaneko, Kunihiko

    2016-01-01

    Search for possible relationships between phylogeny and ontogeny is important in evolutionary-developmental biology. Here we uncover such relationships by numerical evolution and unveil their origin in terms of dynamical systems theory. By representing developmental dynamics of spatially located cells with gene expression dynamics with cell-to-cell interaction under external morphogen gradient, gene regulation networks are evolved under mutation and selection with the fitness to approach a prescribed spatial pattern of expressed genes. For most numerical evolution experiments, evolution of pattern over generations and development of pattern by an evolved network exhibit remarkable congruence. Both in the evolution and development pattern changes consist of several epochs where stripes are formed in a short time, while for other temporal regimes, pattern hardly changes. In evolution, these quasi-stationary regimes are generations needed to hit relevant mutations, while in development, they are due to some gene expression that varies slowly and controls the pattern change. The morphogenesis is regulated by combinations of feedback or feedforward regulations, where the upstream feedforward network reads the external morphogen gradient, and generates a pattern used as a boundary condition for the later patterns. The ordering from up to downstream is common in evolution and development, while the successive epochal changes in development and evolution are represented as common bifurcations in dynamical-systems theory, which lead to the evolution-development congruence. Mechanism of exceptional violation of the congruence is also unveiled. Our results provide a new look on developmental stages, punctuated equilibrium, developmental bottlenecks, and evolutionary acquisition of novelty in morphogenesis. PMID:26678220

  19. Evolution‐development congruence in pattern formation dynamics: Bifurcations in gene expression and regulation of networks structures

    Science.gov (United States)

    Kohsokabe, Takahiro

    2016-01-01

    ABSTRACT Search for possible relationships between phylogeny and ontogeny is important in evolutionary‐developmental biology. Here we uncover such relationships by numerical evolution and unveil their origin in terms of dynamical systems theory. By representing developmental dynamics of spatially located cells with gene expression dynamics with cell‐to‐cell interaction under external morphogen gradient, gene regulation networks are evolved under mutation and selection with the fitness to approach a prescribed spatial pattern of expressed genes. For most numerical evolution experiments, evolution of pattern over generations and development of pattern by an evolved network exhibit remarkable congruence. Both in the evolution and development pattern changes consist of several epochs where stripes are formed in a short time, while for other temporal regimes, pattern hardly changes. In evolution, these quasi‐stationary regimes are generations needed to hit relevant mutations, while in development, they are due to some gene expression that varies slowly and controls the pattern change. The morphogenesis is regulated by combinations of feedback or feedforward regulations, where the upstream feedforward network reads the external morphogen gradient, and generates a pattern used as a boundary condition for the later patterns. The ordering from up to downstream is common in evolution and development, while the successive epochal changes in development and evolution are represented as common bifurcations in dynamical‐systems theory, which lead to the evolution‐development congruence. Mechanism of exceptional violation of the congruence is also unveiled. Our results provide a new look on developmental stages, punctuated equilibrium, developmental bottlenecks, and evolutionary acquisition of novelty in morphogenesis. J. Exp. Zool. (Mol. Dev. Evol.) 326B:61–84, 2016. © 2015 The Authors. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution

  20. Solution NMR structure of CsgE: Structural insights into a chaperone and regulator protein important for functional amyloid formation.

    Science.gov (United States)

    Shu, Qin; Krezel, Andrzej M; Cusumano, Zachary T; Pinkner, Jerome S; Klein, Roger; Hultgren, Scott J; Frieden, Carl

    2016-06-28

    Curli, consisting primarily of major structural subunit CsgA, are functional amyloids produced on the surface of Escherichia coli, as well as many other enteric bacteria, and are involved in cell colonization and biofilm formation. CsgE is a periplasmic accessory protein that plays a crucial role in curli biogenesis. CsgE binds to both CsgA and the nonameric pore protein CsgG. The CsgG-CsgE complex is the curli secretion channel and is essential for the formation of the curli fibril in vivo. To better understand the role of CsgE in curli formation, we have determined the solution NMR structure of a double mutant of CsgE (W48A/F79A) that appears to be similar to the wild-type (WT) protein in overall structure and function but does not form mixed oligomers at NMR concentrations similar to the WT. The well-converged structure of this mutant has a core scaffold composed of a layer of two α-helices and a layer of three-stranded antiparallel β-sheet with flexible N and C termini. The structure of CsgE fits well into the cryoelectron microscopy density map of the CsgG-CsgE complex. We highlight a striking feature of the electrostatic potential surface in CsgE structure and present an assembly model of the CsgG-CsgE complex. We suggest a structural mechanism of the interaction between CsgE and CsgA. Understanding curli formation can provide the information necessary to develop treatments and therapeutic agents for biofilm-related infections and may benefit the prevention and treatment of amyloid diseases. CsgE could establish a paradigm for the regulation of amyloidogenesis because of its unique role in curli formation. PMID:27298344

  1. Evidence of stratabound liquefaction in the formation of fractured topographic margins, cone chains and pit catenas along the Martian Dichotomy Boundary and in Isidis Planitia, Mars.

    Science.gov (United States)

    Gallagher, C.; Balme, M. R.

    2012-04-01

    On the low-lying plains along much of the Martian Dichotomy Boundary (MDB) and in the Isidis impact basin, cones and curving chains of cones, referred to as thumbprint terrain (TPT), are common. In the same settings, pit chains (catenas) occur in orthogonal to curving and conchoidal fracture sets between mesa-like crustal blocks, generally at or near topographic margins. Many of the fractures consist of linked pits rather than simple propagated cracks. These assemblages are often associated with the more disaggregated populations of blocks comprising chaos terrain. We show that the local planimetric arrangement of the cone chains, fractures and pit catenas is strikingly similar in both shape and scale, including lateral separation, length, longitudinal slope and radius of curvature. The summits of cones tend to be closely accordant along individual cone chains. Neighbouring cone chains tend to be mutually accordant on low gradient basin surfaces but generally stepped en echelon closer to the fractured basin margins. Similarly, the crustal blocks (including very isolated block sets) are often mutually stepped, and fractures between these en echelon blocks tend to be very close to horizontal. Hence, many cone chains, fractures and pit catenas in fractures share the property of being arranged along strike. They diverge morphologically by the cone chains being positive forms separated by narrow gulfs but the pit catenas being negative forms separated by planar blocks. All of these characteristics point to the possibility that the arcuate cone chains and the arcuate pit catenas have a common origin. In particular, we hypothesise that the cone chains characteristic of TPT along the MDB and in Isidis are filled, indurated and then exhumed pit catenas revealed by the stripping-away of intervening blocks [cf. 1]. Many other surfaces on Mars are pervaded by pits and pit catenas, with evidence of former water flow through the catenas suggesting that ground-ice thaw played a

  2. Sialic Acid on the Glycosylphosphatidylinositol Anchor Regulates PrP-mediated Cell Signaling and Prion Formation.

    Science.gov (United States)

    Bate, Clive; Nolan, William; Williams, Alun

    2016-01-01

    The prion diseases occur following the conversion of the cellular prion protein (PrP(C)) into disease-related isoforms (PrP(Sc)). In this study, the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrP(C) in prion formation was examined using a cell painting technique. PrP(Sc) formation in two prion-infected neuronal cell lines (ScGT1 and ScN2a cells) and in scrapie-infected primary cortical neurons was increased following the introduction of PrP(C). In contrast, PrP(C) containing a GPI anchor from which the sialic acid had been removed (desialylated PrP(C)) was not converted to PrP(Sc). Furthermore, the presence of desialylated PrP(C) inhibited the production of PrP(Sc) within prion-infected cortical neurons and ScGT1 and ScN2a cells. The membrane rafts surrounding desialylated PrP(C) contained greater amounts of sialylated gangliosides and cholesterol than membrane rafts surrounding PrP(C). Desialylated PrP(C) was less sensitive to cholesterol depletion than PrP(C) and was not released from cells by treatment with glimepiride. The presence of desialylated PrP(C) in neurons caused the dissociation of cytoplasmic phospholipase A2 from PrP-containing membrane rafts and reduced the activation of cytoplasmic phospholipase A2. These findings show that the sialic acid moiety of the GPI attached to PrP(C) modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrP(Sc) formation. These results suggest that pharmacological modification of GPI glycosylation might constitute a novel therapeutic approach to prion diseases.

  3. Illegal formation (creation, reorganization of a juridical person: issues of qualification and legal regulation of liability

    Directory of Open Access Journals (Sweden)

    Natalya Aleksandrovna Egorova

    2015-06-01

    Full Text Available Objective to analyze the disposition of part 1 of Article 173.1 of the Russian Criminal Code and comments to this Article to identify their shortcomings to consider problems of practical application of Article 173.1 and to formulate proposals on legislation improvement aimed at increasing the efficiency of counteraction to illegal formation of a juridical person. Methods a combination of general scientific induction deduction analysis and synthesis and specific scientific formallegal comparative legal sociological content analysis methods. Results the paper proposes an analysis of Article 173.1 of the Criminal Code and the current state of law enforcement practice on criminal cases concerning the illegal formation creation reorganization of a juridical person. Basing on empirical material the authors show the problems in classification of these crimes. The authors conclude that the unsatisfactory results of the struggle against quotshortlivedquot companies result mainly from the imperfection of the existing criminal law and prove the need for decriminalization of these crimes simultaneously establishing administrative liability for such acts and excepting Article 173.1 from the Criminal Code or changing its content. Scientific novelty basing on the existing legal norms modern scientific literature on the topic and materials on applying Article 173.1 of the Russian Criminal Code the article studies the signs of illegal formation creation reorganization of a juridical person which cause the greatest difficulties in the crime qualification and sets out the author39s proposals on legislation improvement in particular an exemplary article of the Administrative Code of the Russian Federation on formation creation reorganization of quotshortlivedrdquo companies. Practical value the judgments and conclusions contained in the article can be used in lawmaking activities for the development of draft laws on introducing changes and amendments to the

  4. Essential Roles and Regulation of the Legionella pneumophila Collagen-Like Adhesin during Biofilm Formation

    OpenAIRE

    Julia Mallegol; Carla Duncan; Akriti Prashar; Jannice So; Low, Donald E.; Mauricio Terebeznik; Cyril Guyard

    2012-01-01

    Legionellosis is mostly caused by Legionella pneumophila (Lp) and is defined by a severe respiratory illness with a case fatality rate ranging from 5 to 80%. In a previous study, we showed that a glycosaminoglycan (GAG)-binding adhesin of Lp, named Lcl, is produced during legionellosis and is unique to the L. pneumophila species. Importantly, a mutant depleted in Lcl (Δlpg2644) is impaired in adhesion to GAGs and epithelial cells and in biofilm formation. Here, we examine the molecular functi...

  5. Differential RNA-seq of Vibrio cholerae identifies the VqmR small RNA as a regulator of biofilm formation.

    Science.gov (United States)

    Papenfort, Kai; Förstner, Konrad U; Cong, Jian-Ping; Sharma, Cynthia M; Bassler, Bonnie L

    2015-02-17

    Quorum sensing (QS) is a process of cell-to-cell communication that enables bacteria to transition between individual and collective lifestyles. QS controls virulence and biofilm formation in Vibrio cholerae, the causative agent of cholera disease. Differential RNA sequencing (RNA-seq) of wild-type V. cholerae and a locked low-cell-density QS-mutant strain identified 7,240 transcriptional start sites with ∼ 47% initiated in the antisense direction. A total of 107 of the transcripts do not appear to encode proteins, suggesting they specify regulatory RNAs. We focused on one such transcript that we name VqmR. vqmR is located upstream of the vqmA gene encoding a DNA-binding transcription factor. Mutagenesis and microarray analyses demonstrate that VqmA activates vqmR transcription, that vqmR encodes a regulatory RNA, and VqmR directly controls at least eight mRNA targets including the rtx (repeats in toxin) toxin genes and the vpsT transcriptional regulator of biofilm production. We show that VqmR inhibits biofilm formation through repression of vpsT. Together, these data provide to our knowledege the first global annotation of the transcriptional start sites in V. cholerae and highlight the importance of posttranscriptional regulation for collective behaviors in this human pathogen.

  6. The C-flame Quenching by Convective Boundary Mixing in Super-AGB Stars and the Formation of Hybrid C/O/Ne White Dwarfs and SN Progenitors

    CERN Document Server

    Denissenkov, Pavel A; Truran, James W; Paxton, Bill

    2013-01-01

    After off-center C ignition in the cores of super-AGB stars the C flame propagates all the way down to the center, trailing behind it the C-shell convective zone, and thus building a degenerate ONe core. This standard picture is obtained in stellar evolution simulations if the bottom C-shell convection boundary is assumed to be a discontinuity associated with a strict interpretation of the Schwarzschild condition for convective instability. However, this boundary is prone to additional mixing processes, such as thermohaline convection and convective boundary mixing. Using hydrodynamic simulations we show that, contrary to previous results, thermohaline mixing is too inefficient to interfere with the C-flame propagation. However, even a small amount of convective boundary mixing removes the physical conditions required for the C-flame propagation all the way to the center. This result holds even if we allow for some turbulent heat transport in the CBM region. As a result, super AGB stars build in their interio...

  7. STAT3 Regulates ABCA3 Expression and Influences Lamellar Body Formation in Alveolar Type II Cells

    OpenAIRE

    Matsuzaki, Yohei; Besnard, Valérie; Clark, Jean C.; Xu, Yan; Wert, Susan E.; Ikegami, Machiko; Whitsett, Jeffrey A.

    2007-01-01

    ATP-Binding Cassette A3 (ABCA3) is a lamellar body associated lipid transport protein required for normal synthesis and storage of pulmonary surfactant in type II cells in the alveoli. In this study, we demonstrate that STAT3, activated by IL-6, regulates ABCA3 expression in vivo and in vitro. ABCA3 mRNA and immunostaining were decreased in adult mouse lungs in which STAT3 was deleted from the respiratory epithelium (Stat3Δ/Δ mice). Consistent with the role of STAT3, intratracheal IL-6 induce...

  8. Caldecrin:A pancreas-derived hypocalcemic factor,regulates osteoclast formation and function

    Institute of Scientific and Technical Information of China (English)

    Mineko; Tomomura; Akito; Tomomura

    2015-01-01

    Caldecrin was originally isolated from the pancreas as afactor that reduced serum calcium levels. This secreted serine protease has chymotrypsin-like activity and is also known as chymotrypsin C; it belongs to the elastase family. Although intravenous administration of caldecrin decreases the serum calcium concentration even when its protease activity is blocked,this effect does require cleavage of caldecrin’s pro-peptide by trypsin,converting it to the mature enzyme. Ectopic intramuscular expression of caldecrin prevented bone resorption in ovariectomized mice. Caldecrin inhibited parathyroid hormone-stimulated calcium release from fetal mouse long bone organ cultures. Furthermore,caldecrin suppressed the formation of osteoclasts from bone marrow cells by inhibiting the receptor activator of nuclear factor-k B ligand(RANKL)-stimulated phospholipase Cγ-calcium oscillation-calcineurinnuclear factor of activated T-cells,cytoplasmic 1 pathway. Caldecrin also suppressed the bone resorption activity of mature osteoclasts by preventing RANKL-stimulated Src activation,calcium entry,and actin ring formation. In vivo and in vitro studies have indicated that caldecrin is a unique multifunctional protease with anti-osteoclastogenic activities that are distinct from its protease activity. Caldecrin might be a potential therapeutic target for the treatment of osteolytic diseases such as osteoporosis and osteoarthritis. This mini-review describes caldecrin’s historical background and its mechanisms of action.

  9. Estrogen Receptor α Regulates β-Cell Formation During Pancreas Development and Following Injury.

    Science.gov (United States)

    Yuchi, Yixing; Cai, Ying; Legein, Bart; De Groef, Sofie; Leuckx, Gunter; Coppens, Violette; Van Overmeire, Eva; Staels, Willem; De Leu, Nico; Martens, Geert; Van Ginderachter, Jo A; Heimberg, Harry; Van de Casteele, Mark

    2015-09-01

    Identifying pathways for β-cell generation is essential for cell therapy in diabetes. We investigated the potential of 17β-estradiol (E2) and estrogen receptor (ER) signaling for stimulating β-cell generation during embryonic development and in the severely injured adult pancreas. E2 concentration, ER activity, and number of ERα transcripts were enhanced in the pancreas injured by partial duct ligation (PDL) along with nuclear localization of ERα in β-cells. PDL-induced proliferation of β-cells depended on aromatase activity. The activation of Neurogenin3 (Ngn3) gene expression and β-cell growth in PDL pancreas were impaired when ERα was turned off chemically or genetically (ERα(-/-)), whereas in situ delivery of E2 promoted β-cell formation. In the embryonic pancreas, β-cell replication, number of Ngn3(+) progenitor cells, and expression of key transcription factors of the endocrine lineage were decreased by ERα inactivation. The current study reveals that E2 and ERα signaling can drive β-cell replication and formation in mouse pancreas.

  10. Par3/Bazooka and phosphoinositides regulate actin protrusion formation during Drosophila dorsal closure and wound healing.

    Science.gov (United States)

    Pickering, Karen; Alves-Silva, Juliana; Goberdhan, Deborah; Millard, Tom H

    2013-02-01

    Effective wound closure mechanisms are essential for maintenance of epithelial structure and function. The repair of wounded epithelia is primarily driven by the cells bordering the wound, which become motile after wounding, forming dynamic actin protrusions along the wound edge. The molecular mechanisms that trigger wound edge cells to become motile following tissue damage are not well understood. Using wound healing and dorsal closure in Drosophila, we identify a direct molecular link between changes in cell-cell adhesion at epithelial edges and induction of actin protrusion formation. We find that the scaffolding protein Par3/Bazooka and the lipid phosphatase Pten are specifically lost from cell-cell junctions at epithelial edges. This results in a localized accumulation of phosphatidylinositol 3,4,5-trisphosphate (PIP3), which promotes the formation of actin protrusions along the epithelial edge. Depleting PIP3 results in defective epithelial closure during both dorsal closure and wound healing. These data reveal a novel mechanism that directly couples loss of epithelial integrity to activation of epithelial closure.

  11. ApoE receptor 2 regulates synapse and dendritic spine formation.

    Directory of Open Access Journals (Sweden)

    Sonya B Dumanis

    Full Text Available BACKGROUND: Apolipoprotein E receptor 2 (ApoEr2 is a postsynaptic protein involved in long-term potentiation (LTP, learning, and memory through unknown mechanisms. We examined the biological effects of ApoEr2 on synapse and dendritic spine formation-processes critical for learning and memory. METHODOLOGY/PRINCIPAL FINDINGS: In a heterologous co-culture synapse assay, overexpression of ApoEr2 in COS7 cells significantly increased colocalization with synaptophysin in primary hippocampal neurons, suggesting that ApoEr2 promotes interaction with presynaptic structures. In primary neuronal cultures, overexpression of ApoEr2 increased dendritic spine density. Consistent with our in vitro findings, ApoEr2 knockout mice had decreased dendritic spine density in cortical layers II/III at 1 month of age. We also tested whether the interaction between ApoEr2 and its cytoplasmic adaptor proteins, specifically X11α and PSD-95, affected synapse and dendritic spine formation. X11α decreased cell surface levels of ApoEr2 along with synapse and dendritic spine density. In contrast, PSD-95 increased cell surface levels of ApoEr2 as well as synapse and dendritic spine density. CONCLUSIONS/SIGNIFICANCE: These results suggest that ApoEr2 plays important roles in structure and function of CNS synapses and dendritic spines, and that these roles are modulated by cytoplasmic adaptor proteins X11α and PSD-95.

  12. Matrix Metalloproteinases: Inflammatory Regulators of Cell Behaviors in Vascular Formation and Remodeling

    Directory of Open Access Journals (Sweden)

    Qishan Chen

    2013-01-01

    Full Text Available Abnormal angiogenesis and vascular remodeling contribute to pathogenesis of a number of disorders such as tumor, arthritis, atherosclerosis, restenosis, hypertension, and neurodegeneration. During angiogenesis and vascular remodeling, behaviors of stem/progenitor cells, endothelial cells (ECs, and vascular smooth muscle cells (VSMCs and its interaction with extracellular matrix (ECM play a critical role in the processes. Matrix metalloproteinases (MMPs, well-known inflammatory mediators are a family of zinc-dependent proteolytic enzymes that degrade various components of ECM and non-ECM molecules mediating tissue remodeling in both physiological and pathological processes. MMPs including MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, and MT1-MMP, are stimulated and activated by various stimuli in vascular tissues. Once activated, MMPs degrade ECM proteins or other related signal molecules to promote recruitment of stem/progenitor cells and facilitate migration and invasion of ECs and VSMCs. Moreover, vascular cell proliferation and apoptosis can also be regulated by MMPs via proteolytically cleaving and modulating bioactive molecules and relevant signaling pathways. Regarding the importance of vascular cells in abnormal angiogenesis and vascular remodeling, regulation of vascular cell behaviors through modulating expression and activation of MMPs shows therapeutic potential.

  13. LIGHT REGULATION OF GROWTH AND MELANIN FORMATION IN Inonotus оbliquus (Pers. Pilat

    Directory of Open Access Journals (Sweden)

    N. L. Poyedinok

    2013-04-01

    Full Text Available The study aims to investigate possibilities of using different sources of low-intensity light for the regulation of mycelium growth and melanin synthesis by medicinal mushroom Inonotus obliquus (Pers. Pilat. Studies of the light’s influence on the linear growth, biomass accumulation and melanin synthesis I. obliquus were performed using experimental installations that provide both lasing (coherent light with specified parameters, as well as sources of incoherent light. It has been demonstrated that the greatest stimulating effect took place during the irradiation of mycelium with blue light. It has been found that further realization of photobiological effect is largely dependent on the method of cultivation. Irradiation with laser light within all studied wavelength ranges was more conducive to growth, biomass and melanin accumulation in the mushroom mycelium than incoherent light irradiation within the same wavelength range. Light treatment made it possible to significantly reduce the duration of fermentation. The results of studies allow considering lowintensity light in the visible part of the spectrum as a perspective growth and biosynthetic activity regulator of I. obliquus in the biotechnology of its cultivation.

  14. Dimer formation and transcription activation in the sporulation response regulator Spo0A.

    Science.gov (United States)

    Lewis, Richard J; Scott, David J; Brannigan, James A; Ladds, Joanne C; Cervin, Marguerite A; Spiegelman, George B; Hoggett, James G; Barák, Imrich; Wilkinson, Anthony J

    2002-02-15

    The response regulator Spo0A is the master control element in the initiation of sporulation in Bacillus subtilis. Like many other multi-domain response regulators, the latent activity of the effector, C-terminal domain is stimulated by phosphorylation on a conserved aspartic acid residue in the regulatory, N-terminal domain. If a threshold concentration of phosphorylated Spo0A is achieved, the transcription of genes required for sporulation is activated, whereas the genes encoding stationary phase sentinels are repressed, and sporulation proceeds. Despite detailed genetic, biochemical and structural characterisation, it is not understood how the phosphorylation signal in the receiver domain is transduced into DNA binding and transcription activation in the distal effector domain. An obstacle to our understanding of Spo0A function is the uncertainty concerning changes in quaternary structure that accompany phosphorylation. Here we have revisited this question and shown unequivocally that Spo0A forms dimers upon phosphorylation and that the subunit interactions in the dimer are mediated principally by the receiver domain. Purified dimers of two mutants of Spo0A, in which the phosphorylatable aspartic acid residue has been substituted, activate transcription from the spoIIG promoter in vitro, whereas monomers do not. This suggests that dimers represent the activated form of Spo0A. PMID:11851334

  15. Neural cell 3D microtissue formation is marked by cytokines' up-regulation.

    Directory of Open Access Journals (Sweden)

    Yinzhi Lai

    Full Text Available Cells cultured in three dimensional (3D scaffolds as opposed to traditional two-dimensional (2D substrates have been considered more physiologically relevant based on their superior ability to emulate the in vivo environment. Combined with stem cell technology, 3D cell cultures can provide a promising alternative for use in cell-based assays or biosensors in non-clinical drug discovery studies. To advance 3D culture technology, a case has been made for identifying and validating three-dimensionality biomarkers. With this goal in mind, we conducted a transcriptomic expression comparison among neural progenitor cells cultured on 2D substrates, 3D porous polystyrene scaffolds, and as 3D neurospheres (in vivo surrogate. Up-regulation of cytokines as a group in 3D and neurospheres was observed. A group of 13 cytokines were commonly up-regulated in cells cultured in polystyrene scaffolds and neurospheres, suggesting potential for any or a combination from this list to serve as three-dimensionality biomarkers. These results are supportive of further cytokine identification and validation studies with cells from non-neural tissue.

  16. Platelet-Derived CCL5 Regulates CXC Chemokine Formation and Neutrophil Recruitment in Acute Experimental Colitis.

    Science.gov (United States)

    Yu, Changhui; Zhang, Songen; Wang, Yongzhi; Zhang, Su; Luo, Lingtao; Thorlacius, Henrik

    2016-02-01

    Accumulating data suggest that platelets not only regulate thrombosis and haemostasis but also inflammatory processes. Platelets contain numerous potent pro-inflammatory compounds, including the chemokines CCL5 and CXCL4, although their role in acute colitis remains elusive. The aim of this study is to examine the role of platelets and platelet-derived chemokines in acute colitis. Acute colitis is induced in female Balb/c mice by administration of 5% dextran sodium sulfate (DSS) for 5 days. Animals receive a platelet-depleting, anti-CCL5, anti-CXCL4, or a control antibody prior to DSS challenge. Colonic tissue is collected for quantification of myeloperoxidase (MPO) activity, CXCL5, CXCL2, interleukin-6 (IL-6), and CCL5 levels as well as morphological analyses. Platelet depletion reduce tissue damage and clinical disease activity index in DSS-exposed animals. Platelet depletion not only reduces levels of CXCL2 and CXCL5 but also levels of CCL5 in the inflamed colon. Immunoneutralization of CCL5 but not CXCL4 reduces tissue damage, CXC chemokine expression, and neutrophil recruitment in DSS-treated animals. These findings show that platelets play a key role in acute colitis by regulating CXC chemokine generation, neutrophil infiltration, and tissue damage in the colon. Moreover, our results suggest that platelet-derived CCL5 is an important link between platelet activation and neutrophil recruitment in acute colitis.

  17. Mind Bomb-2 Regulates Hippocampus-dependent Memory Formation and Synaptic Plasticity.

    Science.gov (United States)

    Kim, Somi; Kim, TaeHyun; Lee, Hye-Ryeon; Kong, Young-Yun; Kaang, Bong-Kiun

    2015-11-01

    Notch signaling is a key regulator of neuronal fate during embryonic development, but its function in the adult brain is still largely unknown. Mind bomb-2 (Mib2) is an essential positive regulator of the Notch pathway, which acts in the Notch signal-sending cells. Therefore, genetic deletion of Mib2 in the mouse brain might help understand Notch signaling-mediated cell-cell interactions between neurons and their physiological function. Here we show that deletion of Mib2 in the mouse brain results in impaired hippocampal spatial memory and contextual fear memory. Accordingly, we found impaired hippocampal synaptic plasticity in Mib2 knock-out (KO) mice; however, basal synaptic transmission did not change at the Schaffer collateral-CA1 synapses. Using western blot analysis, we found that the level of cleaved Notch1 was lower in Mib2 KO mice than in wild type (WT) littermates after mild foot shock. Taken together, these data suggest that Mib2 plays a critical role in synaptic plasticity and spatial memory through the Notch signaling pathway.

  18. WIP regulates persistence of cell migration and ruffle formation in both mesenchymal and amoeboid modes of motility.

    Directory of Open Access Journals (Sweden)

    Inmaculada Banon-Rodriguez

    Full Text Available The spatial distribution of signals downstream from receptor tyrosine kinases (RTKs or G-protein coupled receptors (GPCR regulates fundamental cellular processes that control cell migration and growth. Both pathways rely significantly on actin cytoskeleton reorganization mediated by nucleation-promoting factors such as the WASP-(Wiskott-Aldrich Syndrome Protein family. WIP (WASP Interacting Protein is essential for the formation of a class of polarised actin microdomain, namely dorsal ruffles, downstream of the RTK for PDGF (platelet-derived growth factor but the underlying mechanism is poorly understood. Using lentivirally-reconstituted WIP-deficient murine fibroblasts we define the requirement for WIP interaction with N-WASP (neural WASP and Nck for efficient dorsal ruffle formation and of WIP-Nck binding for fibroblast chemotaxis towards PDGF-AA. The formation of both circular dorsal ruffles in PDGF-AA-stimulated primary fibroblasts and lamellipodia in CXCL13-treated B lymphocytes are also compromised by WIP-deficiency. We provide data to show that a WIP-Nck signalling complex interacts with RTK to promote polarised actin remodelling in fibroblasts and provide the first evidence for WIP involvement in the control of migratory persistence in both mesenchymal (fibroblast and amoeboid (B lymphocytes motility.

  19. Class I PI-3-Kinase Signaling Is Critical for Bone Formation Through Regulation of SMAD1 Activity in Osteoblasts.

    Science.gov (United States)

    Gámez, Beatriz; Rodríguez-Carballo, Edgardo; Graupera, Mariona; Rosa, José Luis; Ventura, Francesc

    2016-08-01

    Bone formation and homeostasis is carried out by osteoblasts, whose differentiation and activity are regulated by osteogenic signaling networks. A central mediator of these inputs is the lipid kinase phosphatidylinositol 3-kinase (PI3K). However, at present, there are no data on the specific role of distinct class IA PI3K isoforms in bone biology. Here, we performed osteoblast-specific deletion in mice to show that both p110α and p110β isoforms are required for survival and differentiation and function of osteoblasts and thereby control bone formation and postnatal homeostasis. Impaired osteogenesis arises from increased GSK3 activity and a depletion of SMAD1 protein levels in PI3K-deficient osteoblasts. Accordingly, pharmacological inhibition of GSK3 activity or ectopic expression of SMAD1 or SMAD5 normalizes bone morphogenetic protein (BMP) transduction and osteoblast differentiation. Together, these results identify the PI3K-GSK3-SMAD1 axis as a central node integrating multiple signaling networks that govern bone formation and homeostasis. © 2016 American Society for Bone and Mineral Research. PMID:26896753

  20. Pathways Regulating Spheroid Formation of Human Follicular Thyroid Cancer Cells under Simulated Microgravity Conditions: A Genetic Approach

    Directory of Open Access Journals (Sweden)

    Stefan Riwaldt

    2016-04-01

    Full Text Available Microgravity induces three-dimensional (3D growth in numerous cell types. Despite substantial efforts to clarify the underlying mechanisms for spheroid formation, the precise molecular pathways are still not known. The principal aim of this paper is to compare static 1g-control cells with spheroid forming (MCS and spheroid non-forming (AD thyroid cancer cells cultured in the same flask under simulated microgravity conditions. We investigated the morphology and gene expression patterns in human follicular thyroid cancer cells (UCLA RO82-W-1 cell line after a 24 h-exposure on the Random Positioning Machine (RPM and focused on 3D growth signaling processes. After 24 h, spheroid formation was observed in RPM-cultures together with alterations in the F-actin cytoskeleton. qPCR indicated more changes in gene expression in MCS than in AD cells. Of the 24 genes analyzed VEGFA, VEGFD, MSN, and MMP3 were upregulated in MCS compared to 1g-controls, whereas ACTB, ACTA2, KRT8, TUBB, EZR, RDX, PRKCA, CAV1, MMP9, PAI1, CTGF, MCP1 were downregulated. A pathway analysis revealed that the upregulated genes code for proteins, which promote 3D growth (angiogenesis and prevent excessive accumulation of extracellular proteins, while genes coding for structural proteins are downregulated. Pathways regulating the strength/rigidity of cytoskeletal proteins, the amount of extracellular proteins, and 3D growth may be involved in MCS formation.

  1. Negative Regulation of Leptin-induced Reactive Oxygen Species (ROS) Formation by Cannabinoid CB1 Receptor Activation in Hypothalamic Neurons.

    Science.gov (United States)

    Palomba, Letizia; Silvestri, Cristoforo; Imperatore, Roberta; Morello, Giovanna; Piscitelli, Fabiana; Martella, Andrea; Cristino, Luigia; Di Marzo, Vincenzo

    2015-05-29

    The adipocyte-derived, anorectic hormone leptin was recently shown to owe part of its regulatory effects on appetite-regulating hypothalamic neuropeptides to the elevation of reactive oxygen species (ROS) levels in arcuate nucleus (ARC) neurons. Leptin is also known to exert a negative regulation on hypothalamic endocannabinoid levels and hence on cannabinoid CB1 receptor activity. Here we investigated the possibility of a negative regulation by CB1 receptors of leptin-mediated ROS formation in the ARC. Through pharmacological and molecular biology experiments we report data showing that leptin-induced ROS accumulation is 1) blunted by arachidonyl-2'-chloroethylamide (ACEA) in a CB1-dependent manner in both the mouse hypothalamic cell line mHypoE-N41 and ARC neuron primary cultures, 2) likewise blocked by a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, troglitazone, in a manner inhibited by T0070907, a PPAR-γ antagonist that also inhibited the ACEA effect on leptin, 3) blunted under conditions of increased endocannabinoid tone due to either pharmacological or genetic inhibition of endocannabinoid degradation in mHypoE-N41 and primary ARC neuronal cultures from MAGL(-/-) mice, respectively, and 4) associated with reduction of both PPAR-γ and catalase activity, which are reversed by both ACEA and troglitazone. We conclude that CB1 activation reverses leptin-induced ROS formation and hence possibly some of the ROS-mediated effects of the hormone by preventing PPAR-γ inhibition by leptin, with subsequent increase of catalase activity. This mechanism might underlie in part CB1 orexigenic actions under physiopathological conditions accompanied by elevated hypothalamic endocannabinoid levels.

  2. The SOS Response Master Regulator LexA Is Associated with Sporulation, Motility and Biofilm Formation in Clostridium difficile.

    Science.gov (United States)

    Walter, Beata M; Cartman, Stephen T; Minton, Nigel P; Butala, Matej; Rupnik, Maja

    2015-01-01

    The LexA regulated SOS network is a bacterial response to DNA damage of metabolic or environmental origin. In Clostridium difficile, a nosocomial pathogen causing a range of intestinal diseases, the in-silico deduced LexA network included the core SOS genes involved in the DNA repair and genes involved in various other biological functions that vary among different ribotypes. Here we describe the construction and characterization of a lexA ClosTron mutant in C. difficile R20291 strain. The mutation of lexA caused inhibition of cell division resulting in a filamentous phenotype. The lexA mutant also showed decreased sporulation, a reduction in swimming motility, greater sensitivity to metronidazole, and increased biofilm formation. Changes in the regulation of toxin A, but not toxin B, were observed in the lexA mutant in the presence of sub-inhibitory concentrations of levofloxacin. C. difficile LexA is, therefore, not only a regulator of DNA damage but also controls many biological functions associated with virulence.

  3. Magnetically Regulated Star Formation in 3D: The Case of Taurus Molecular Cloud Complex

    CERN Document Server

    Nakamura, Fumitaka

    2008-01-01

    We carry out three-dimensional MHD simulations of star formation in turbulent, magnetized clouds, including ambipolar diffusion and feedback from protostellar outflows. The calculations focus on relatively diffuse clouds threaded by a strong magnetic field capable of resisting severe tangling by turbulent motions and retarding global gravitational contraction in the cross-field direction. They are motivated by observations of the Taurus molecular cloud complex (and, to a lesser extent, Pipe Nebula), which shows an ordered large-scale magnetic field, as well as elongated condensations that are generally perpendicular to the large-scale field. We find that stars form in earnest in such clouds when enough material has settled gravitationally along the field lines that the mass-to-flux ratios of the condensations approach the critical value. Only a small fraction (of order 1% or less) of the nearly magnetically-critical, condensed material is turned into stars per local free-fall time, however. The slow star form...

  4. Differential regulation of macropinocytosis in macrophages by cytokines: implications for foam cell formation and atherosclerosis.

    Science.gov (United States)

    Michael, Daryn R; Ashlin, Tim G; Davies, Charlotte S; Gallagher, Hayley; Stoneman, Thomas W; Buckley, Melanie L; Ramji, Dipak P

    2013-10-01

    A key event during the formation of lipid-rich foam cells during the progression of atherosclerosis is the uptake of modified low-density lipoproteins (LDL) by macrophages in response to atherogenic mediators in the arterial intima. In addition to scavenger receptor-dependent uptake of LDL, macropinocytosis is known to facilitate the uptake of LDL through the constitutive and passive internalization of large quantities of extracellular solute. In this study we confirm the ability of macropinocytosis to facilitate the uptake of modified LDL by human macrophages and show its modulation by TGF-β, IFN-γ, IL-17A and IL-33. Furthermore we show that the TGF-β-mediated inhibition of macropinocytosis is a Smad-2/-3-independent process.

  5. Ewing sarcoma EWS protein regulates midzone formation by recruiting Aurora B kinase to the midzone.

    Science.gov (United States)

    Park, Hyewon; Turkalo, Timothy K; Nelson, Kayla; Folmsbee, Stephen Sai; Robb, Caroline; Roper, Brittany; Azuma, Mizuki

    2014-01-01

    Ewing sarcoma is a malignant bone cancer that primarily occurs in children and adolescents. Eighty-five percent of Ewing sarcoma is characterized by the presence of the aberrant chimeric EWS/FLI1 fusion gene. Previously, we demonstrated that an interaction between EWS/FLI1 and wild-type EWS led to the inhibition of EWS activity and mitotic dysfunction. Although defective mitosis is considered to be a critical step in cancer initiation, it is unknown how interference with EWS contributes to Ewing sarcoma formation. Here, we demonstrate that EWS/FLI1- and EWS-knockdown cells display a high incidence of defects in the midzone, a midline structure located between segregating chromatids during anaphase. Defects in the midzone can lead to the failure of cytokinesis and can result in the induction of aneuploidy. The similarity among the phenotypes of EWS/FLI1- and EWS siRNA-transfected HeLa cells points to the inhibition of EWS as the key mechanism for the induction of midzone defects. Supporting this observation, the ectopic expression of EWS rescues the high incidence of midzone defects observed in Ewing sarcoma A673 cells. We discovered that EWS interacts with Aurora B kinase, and that EWS is also required for recruiting Aurora B to the midzone. A domain analysis revealed that the R565 in the RGG3 domain of EWS is essential for both Aurora B interaction and the recruitment of Aurora B to the midzone. Here, we propose that the impairment of EWS-dependent midzone formation via the recruitment of Aurora B is a potential mechanism of Ewing sarcoma development.

  6. POLRMT regulates the switch between replication primer formation and gene expression of mammalian mtDNA.

    Science.gov (United States)

    Kühl, Inge; Miranda, Maria; Posse, Viktor; Milenkovic, Dusanka; Mourier, Arnaud; Siira, Stefan J; Bonekamp, Nina A; Neumann, Ulla; Filipovska, Aleksandra; Polosa, Paola Loguercio; Gustafsson, Claes M; Larsson, Nils-Göran

    2016-08-01

    Mitochondria are vital in providing cellular energy via their oxidative phosphorylation system, which requires the coordinated expression of genes encoded by both the nuclear and mitochondrial genomes (mtDNA). Transcription of the circular mammalian mtDNA depends on a single mitochondrial RNA polymerase (POLRMT). Although the transcription initiation process is well understood, it is debated whether POLRMT also serves as the primase for the initiation of mtDNA replication. In the nucleus, the RNA polymerases needed for gene expression have no such role. Conditional knockout of Polrmt in the heart results in severe mitochondrial dysfunction causing dilated cardiomyopathy in young mice. We further studied the molecular consequences of different expression levels of POLRMT and found that POLRMT is essential for primer synthesis to initiate mtDNA replication in vivo. Furthermore, transcription initiation for primer formation has priority over gene expression. Surprisingly, mitochondrial transcription factor A (TFAM) exists in an mtDNA-free pool in the Polrmt knockout mice. TFAM levels remain unchanged despite strong mtDNA depletion, and TFAM is thus protected from degradation of the AAA(+) Lon protease in the absence of POLRMT. Last, we report that mitochondrial transcription elongation factor may compensate for a partial depletion of POLRMT in heterozygous Polrmt knockout mice, indicating a direct regulatory role of this factor in transcription. In conclusion, we present in vivo evidence that POLRMT has a key regulatory role in the replication of mammalian mtDNA and is part of a transcriptional mechanism that provides a switch between primer formation for mtDNA replication and mitochondrial gene expression. PMID:27532055

  7. In vitro approach to the mechanics of lipid membrane area regulation: vesicle absorption and tube formation

    Science.gov (United States)

    Staykova, Margarita; Holmes, Douglas; Read, Clarke; Stone, Howard A.

    2011-03-01

    We have designed an experimental approach that allows us to study the response of supported lipid bilayers to cycles of biaxial expansion and compression. We observed that the bilayer effectively adjusts its area during dilatational or compressive strains in order to reduce its tension. For example, if there is a sufficient lipid reservoir in the form of attached vesicles, then a lipid bilayer may accommodate strains tens of times larger than the critical strain for rupture by expanding its area. Additionally, upon compression the bilayer reduces its area by expelling lipid tubes out of its plane. These observations offer new insights into how cells regulate their surface area in response to various mechanical stimuli, i.e. during physiological volume changes, locomotion, cyclic expansion and compression of the uro- and the alveolar- epithelium, etc.

  8. Networks of fibers and factors: regulation of capsule formation in Cryptococcus neoformans.

    Science.gov (United States)

    Ding, Hao; Mayer, François L; Sánchez-León, Eddy; de S Araújo, Glauber R; Frases, Susana; Kronstad, James W

    2016-01-01

    The ability of the pathogenic fungus Cryptococcus neoformans to cause life-threatening meningoencephalitis in immunocompromised individuals is due in large part to elaboration of a capsule consisting of polysaccharide fibers. The size of the cell-associated capsule is remarkably responsive to a variety of environmental and host conditions, but the mechanistic details of the regulation, synthesis, trafficking, and attachment of the polysaccharides are poorly understood. Recent studies reveal a complex network of transcription factors that influence capsule elaboration in response to several different signals of relevance to disease (e.g., iron deprivation). The emerging complexity of the network is consistent with the diversity of conditions that influence the capsule and illustrates the responsiveness of the fungus to both the environment and mammalian hosts. PMID:27516877

  9. The Impact of Immune System in Regulating Bone Metastasis Formation by Osteotropic Tumors

    Directory of Open Access Journals (Sweden)

    Lucia D’Amico

    2015-01-01

    Full Text Available Bone metastases are frequent and debilitating consequence for many tumors, such as breast, lung, prostate, and kidney cancer. Many studies report the importance of the immune system in the pathogenesis of bone metastasis. Indeed, bone and immune system are strictly linked to each other because bone regulates the hematopoietic stem cells from which all cells of the immune system derive, and many immunoregulatory cytokines influence the fate of bone cells. Furthermore, both cytokines and factors produced by immune and bone cells promote the growth of tumor cells in bone, contributing to supporting the vicious cycle of bone metastasis. This review summarizes the current knowledge on the interactions among bone, immune, and tumor cells aiming to provide an overview of the osteoimmunology field in bone metastasis from solid tumors.

  10. Palynology of the Lost Branch Formation of Kansas - new insights on the major floral transition at the Middle-Upper Pennsylvanian boundary

    Energy Technology Data Exchange (ETDEWEB)

    Peppers, R.A. [Illinois State Geological Survey, Champaign, IL (United States)

    1997-12-01

    Palynological assemblages from two outcrops of the upper part of the Memorial Formation, the Lost Branch Formation and the overlying Hepler unit in Kansas, were examined to discover which stratigraphic interval marks the change from the lycopod-dominated coal swamp floras of Middle Pennylsvanian (Westphalian D) age to the fern-dominated coal swamp floras of Late Pennsylvanian (Stephanian) age.

  11. Emerging boundaries

    DEFF Research Database (Denmark)

    Løvschal, Mette

    2014-01-01

    and formalization. These principles are then used to argue the case for socioconceptual emergence and causality between the lines. This causality appears only in a long-term perspective and implies that, although the development of these boundaries was chronologically displaced across northwestern......This article proposes a processual ontology for the emergence of man-made, linear boundaries across northwestern Europe, particularly in the first millennium BC. Over a significant period of time, these boundaries became new ways of organizing the landscape and settlements—a phenomenon that has...... Europe, elements of this phenomenon emerged along equivalent trajectories. At the same time, variation in the regional incorporation of these linear phenomena points toward situation-specific applications and independent development....

  12. Role of slow relaxation processes in the formation of the Kapitza jump on the boundary between a superconductor and a dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Zelikman, M.A.; Spivak, B.Z.

    1979-02-01

    The effect of slow relaxation of excitons in a superconductor on the thermal Kapitza resistance between a superconductor and a dielectric is considered. It is shown that the presence of a hierarchy of relaxation length in the superconductor leads to the existence near the boundary of a region that is in strong disequilibrium. The observed Kapitza jump depends on the size of the energy gap. The results of the theory agree in order of magnitude with experiment.

  13. Growth plate regulation and osteochondroma formation: insights from tracing proteoglycans in zebrafish models and human cartilage.

    Science.gov (United States)

    de Andrea, Carlos E; Prins, Frans A; Wiweger, Malgorzata I; Hogendoorn, Pancras C W

    2011-06-01

    Proteoglycans are secreted into the extracellular matrix of virtually all cell types and function in several cellular processes. They consist of a core protein onto which glycosaminoglycans (e.g., heparan or chondroitin sulphates), are attached. Proteoglycans are important modulators of gradient formation and signal transduction. Impaired biosynthesis of heparan sulphate glycosaminoglycans causes osteochondroma, the most common bone tumour to occur during adolescence. Cytochemical staining with positively charged dyes (e.g., polyethyleneimine-PEI) allows, visualisation of proteoglycans and provides a detailed description of how proteoglycans are distributed throughout the cartilage matrix. PEI staining was studied by electron and reflection contrast microscopy in human growth plates, osteochondromas and five different proteoglycan-deficient zebrafish mutants displaying one of the following skeletal phenotypes: dackel (dak/ext2), lacking heparan sulphate and identified as a model for human multiple osteochondromas; hi307 (β3gat3), deficient for most glycosaminoglycans; pinscher (pic/slc35b2), presenting with defective sulphation of glycosaminoglycans; hi954 (uxs1), lacking most glycosaminoglycans; and knypek (kny/gpc4), missing the protein core of the glypican-4 proteoglycan. The panel of genetically well-characterized proteoglycan-deficient zebrafish mutants serves as a convincing and comprehensive study model to investigate proteoglycan distribution and the relation of this distribution to the model mutation status. They also provide insight into the distributions and gradients that can be expected in the human homologue. Human growth plate, wild-type zebrafish and fish mutants with mild proteoglycan defects (hi307 and kny) displayed proteoglycans distributed in a gradient throughout the matrix. Although the mutants pic and hi954, which had severely impaired proteoglycan biosynthesis, showed no PEI staining, dak mutants demonstrated reduced PEI staining and no

  14. The exopolysaccharide gene cluster Bcam1330-Bcam1341 is involved in Burkholderia cenocepacia biofilm formation, and its expression is regulated by c-di-GMP and Bcam1349

    DEFF Research Database (Denmark)

    Fazli, Mustafa; McCarthy, Yvonne; Givskov, Michael;

    2013-01-01

    In Burkholderia cenocepacia, the second messenger cyclic diguanosine monophosphate (c-di-GMP) has previously been shown to positively regulate biofilm formation and the expression of cellulose and type-I fimbriae genes through binding to the transcriptional regulator Bcam1349. Here, we provide...... evidence that cellulose and type-I fimbriae are not involved in B. cenocepacia biofilm formation in flow chambers, and we identify a novel Bcam1349/c-di-GMP-regulated exopolysaccharide gene cluster which is essential for B. cenocepacia biofilm formation. Overproduction of Bcam1349 in trans promotes wrinkly...... matrix exopolysaccharide and to be essential for flow-chamber biofilm formation. We demonstrate that Bcam1349 binds to the promoter region of genes in the Bcam1330-Bcam1341 cluster and that this binding is enhanced by the presence of c-di-GMP. Furthermore, we demonstrate that overproduction of both c-di-GMP...

  15. Changing Boundaries

    DEFF Research Database (Denmark)

    Brodkin, Evelyn; Larsen, Flemming

    2013-01-01

    In recent decades, workfare-style policies have become part of the institutional architecture of welfare and labor market arrangements around the world. In this article, we offer a comparative, historical view of workfare´s advance. Our analysis recognizes the complexity and diversity of what we...... project that is altering the boundary between the democratic welfare state and the market economy. We see workfare policies as boundary-changing with potentially profound implications both for individuals disadvantaged by market arrangements and for societies seeking to grapple with the increasing...

  16. Galaxy Zoo and ALFALFA: Atomic Gas and the Regulation of Star Formation in Barred Disc Galaxies

    CERN Document Server

    Masters, Karen L; Haynes, Martha P; Keel, William C; Lintott, Chris; Simmons, Brooke; Skibba, Ramin; Bamford, Steven; Giovanelli, Riccardo; Schawinski, Kevin

    2012-01-01

    We study the observed correlation between atomic gas content and the likelihood of hosting a large scale bar in a sample of 2090 disc galaxies. Such a test has never been done before on this scale. We use data on morphologies from the Galaxy Zoo project and information on the galaxies' HI content from the ALFALFA blind HI survey. Our main result is that the bar fraction is significantly lower among gas rich disc galaxies than gas poor ones. This is not explained by known trends for more massive (stellar) and redder disc galaxies to host more bars and have lower gas fractions: we still see at fixed stellar mass a residual correlation between gas content and bar fraction. We discuss three possible causal explanations: (1) bars in disc galaxies cause atomic gas to be used up more quickly, (2) increasing the atomic gas content in a disc galaxy inhibits bar formation, and (3) bar fraction and gas content are both driven by correlation with environmental effects (e.g. tidal triggering of bars, combined with strangu...

  17. How the First Stars Regulated Star Formation: Enrichment by Nearby Supernovae

    CERN Document Server

    Chen, Ke-Jung; Wollenberg, Katharina M J; Glover, Simon C O; Klessen, Ralf S

    2016-01-01

    Metals from Population III (Pop III) supernovae led to the formation of less massive Pop II stars in the early universe, altering the course of evolution of primeval galaxies and cosmological reionization. There are a variety of scenarios in which heavy elements from the first supernovae were taken up into second-generation stars, but cosmological simulations only model them on the largest scales. We present small-scale, high-resolution simulations of the chemical enrichment of a primordial halo by a nearby supernova after partial evaporation by the progenitor star. We find that ejecta from the explosion crash into and mix violently with ablative flows driven off the halo by the star, creating dense, enriched clumps capable of collapsing into Pop II stars. Metals may mix less efficiently with the partially exposed core of the halo, and it can form either Pop III or Pop II stars. Both Pop II and III stars may thus form after the collision if the ejecta do not strip all the gas from the halo. The partial evapor...

  18. CREB Regulates Experience-Dependent Spine Formation and Enlargement in Mouse Barrel Cortex

    Directory of Open Access Journals (Sweden)

    Annabella Pignataro

    2015-01-01

    Full Text Available Experience modifies synaptic connectivity through processes that involve dendritic spine rearrangements in neuronal circuits. Although cAMP response element binding protein (CREB has a key function in spines changes, its role in activity-dependent rearrangements in brain regions of rodents interacting with the surrounding environment has received little attention so far. Here we studied the effects of vibrissae trimming, a widely used model of sensory deprivation-induced cortical plasticity, on processes associated with dendritic spine rearrangements in the barrel cortex of a transgenic mouse model of CREB downregulation (mCREB mice. We found that sensory deprivation through prolonged whisker trimming leads to an increased number of thin spines in the layer V of related barrel cortex (Contra in wild type but not mCREB mice. In the barrel field controlling spared whiskers (Ipsi, the same trimming protocol results in a CREB-dependent enlargement of dendritic spines. Last, we demonstrated that CREB regulates structural rearrangements of synapses that associate with dynamic changes of dendritic spines. Our findings suggest that CREB plays a key role in dendritic spine dynamics and synaptic circuits rearrangements that account for new brain connectivity in response to changes in the environment.

  19. Physicochemical properties of nanoparticles regulate translocation across pulmonary surfactant monolayer and formation of lipoprotein corona.

    Science.gov (United States)

    Hu, Guoqing; Jiao, Bao; Shi, Xinghua; Valle, Russell P; Fan, Qihui; Zuo, Yi Y

    2013-12-23

    Interaction with the pulmonary surfactant film, being the first line of host defense, represents the initial bio-nano interaction in the lungs. Such interaction determines the fate of the inhaled nanoparticles and their potential therapeutic or toxicological effect. Despite considerable progress in optimizing physicochemical properties of nanoparticles for improved delivery and targeting, the mechanisms by which inhaled nanoparticles interact with the pulmonary surfactant film are still largely unknown. Here, using combined in vitro and in silico methods, we show how hydrophobicity and surface charge of nanoparticles differentially regulate the translocation and interaction with the pulmonary surfactant film. While hydrophilic nanoparticles generally translocate quickly across the pulmonary surfactant film, a significant portion of hydrophobic nanoparticles are trapped by the surfactant film and encapsulated in lipid protrusions upon film compression. Our results support a novel model of pulmonary surfactant lipoprotein corona associated with inhaled nanoparticles of different physicochemical properties. Our data suggest that the study of pulmonary nanotoxicology and nanoparticle-based pulmonary drug delivery should consider this lipoprotein corona.

  20. Gravity-dependent regulation of red light induced moss protonemata branching and gametophore bud formation

    Science.gov (United States)

    Ripetskyj, R. T.; Kit, N. A.

    Isolated leafy shoots of the moss Pottia intermedia positioned horizontally on the agar surface in vertically oriented petri dishes regenerate unbranching negatively gravitropic protonemata on upper side of the regenerant. Gravity determines the site of regeneration not the process itself. White light of low intensity unsufficient to induce positive phototropism of dark-grown protonemata can, however, provoke their branching and gametophore bud formation (Ripetskyj et al., 1998; 1999). The presented experiments have been carried out with red light in Biological Research in Canisters/Light Emitting Diode (BRIC/LED) hardware developed at Kennedy Space Center, USA. Seven-day-old dark-grown negatively gravitropic secondary P. intermedia protonemata were positioned differently with respect to gravity vector and to the source of red light of low, 1 or 2 μ mol\\cdot m-2\\cdot s-1, intensities. The light induced intensive branching of the protonemata and gametophore bud formation initiation site of both processes as well as the direction of growth of branches and buds being depent on the position of protonemata with respect to gravity and light vectors. Vertically positioned, i.e. ungravistimulated, dark grown protonemata illuminated from one side with red light of 2 μ mol\\cdot m-2\\cdot s-1 intensity produced 96,9 ± 2,2% of side branches and buds growing directly towards the light source from the lit protonema side. Horizontally disposed protonemata irradiated from below with red light of the same intensity regenerate 31,7 ± 3,9% of branches and buds on the upper, i.e. shaded protonemata side, the upward growth of which should undoubtedly be determined by gravity. In vertically disposed protonemata illuminated with red light of 1 μ mol\\cdot m-2\\cdot s-1 intensity from aside 31,9 ± 5,5% of side branches and buds arised on shaded protonema side and grew away from the light. Illumination of the protonemata in horizontal position from below increased the number of

  1. Constitutive formation of an RXFP1-signalosome: a novel paradigm in GPCR function and regulation.

    Science.gov (United States)

    Halls, Michelle L

    2012-03-01

    The classical second messenger cAMP is important in diverse physiological processes, where its spatial and temporal compartmentalization allows precise control over multiple cellular events. Within this context, G-protein-coupled receptors (GPCRs) govern specialized pools of cAMP, which are functionally specific for the unique cellular effects attributed to a particular system. The relaxin receptor, RXFP1, is a GPCR that exerts pleiotropic physiological effects including a potent anti-fibrotic response, increased cancer metastases, and has efficacy as a vasodilator in heart failure. On a cellular level, relaxin stimulation of RXFP1 results in the activation of multiple G-protein pathways affecting cAMP accumulation. Specificity and diversity in the cAMP signal generated by RXFP1 is controlled by differential G-protein coupling dependent upon the background of cellular expression, and cAMP compartmentalization. Further complexity in cAMP signalling results from the constitutive assembly of an RXFP1-signalosome, which specifically responds to low concentrations of relaxin, and activates a distinct cAMP pathway. The RXFP1-signalosome is a higher-order protein complex that facilitates receptor sensitivity to attomolar concentration of peptide, exhibits constitutive activity and dual coupling to G-proteins and β-arrestins and reveals a concentration-biased agonism mediated by relaxin. The specific and directed formation of GPCR-centered signalosomes allows an even greater spatial and temporal control of cAMP, thus rationalizing the considerable physiological scope of this ubiquitous second messenger. PMID:21557732

  2. Increased abscess formation and defective chemokine regulation in CREB transgenic mice.

    Directory of Open Access Journals (Sweden)

    Andy Y Wen

    Full Text Available Cyclic AMP-response element-binding protein (CREB is a transcription factor implicated in growth factor-dependent cell proliferation and survival, glucose homeostasis, spermatogenesis, circadian rhythms, and synaptic plasticity associated with memory. To study the phenotype of CREB overexpression in vivo, we generated CREB transgenic (TG mice in which a myeloid specific hMRP8 promoter drives CREB expression. CREB TG mice developed spontaneous skin abscesses more frequently than wild type (WT mice. To understand the role of CREB in myeloid function and innate immunity, chemokine expression in bone marrow derived macrophages (BMDMs from CREB TG mice were compared with BMDMs from WT mice. Our results demonstrated decreased Keratinocyte-derived cytokine (KC in CREB TG BMDMs but not TNFα protein production in response to lipid A (LPA. In addition, mRNA expression of KC and IL-1β (Interleukin-1β was decreased in CREB TG BMDMs; however, there was no difference in the mRNA expression of TNFα, MCP-1, IL-6 and IL-12p40. The mRNA expression of IL-1RA and IL-10 was decreased in response to LPA. Nuclear factor kappa B (NFκB expression and a subset of its target genes were upregulated in CREB TG mouse BMDMs. Although neutrophil migration was the same in both CREB TG and WT mice, Nicotinamide adenine dinucleotide phosphate (NADPH oxidase activity was significantly increased in neutrophils from CREB TG mice. Taken together, CREB overexpression in myeloid cells results in increased abscess formation in vivo and aberrant cytokine and chemokine response, and neutrophil function in vitro.

  3. Solvent Role in the Formation of Electric Double Layers with Surface Charge Regulation: A Bystander or a Key Participant?

    Science.gov (United States)

    Fleharty, Mark E.; van Swol, Frank; Petsev, Dimiter N.

    2016-01-01

    The charge formation at interfaces involving electrolyte solutions is due to the chemical equilibrium between the surface reactive groups and the potential determining ions in the solution (i.e., charge regulation). In this Letter we report our findings that this equilibrium is strongly coupled to the precise molecular structure of the solution near the charged interface. The neutral solvent molecules dominate this structure due to their overwhelmingly large number. Treating the solvent as a structureless continuum leads to a fundamentally inadequate physical picture of charged interfaces. We show that a proper account of the solvent effect leads to an unexpected and complex system behavior that is affected by the molecular and ionic excluded volumes and van der Waals interactions.

  4. Negotiating boundaries

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke

    2010-01-01

    To move treatment successfully from the hospital to that of technology assisted self-care at home, it is vital in the design of such technologies to understand the setting in which the health IT should be used. Based on qualitative studies we find that people engage in elaborate boundary work...

  5. Blurring Boundaries

    DEFF Research Database (Denmark)

    Neergaard, Ulla; Nielsen, Ruth

    2010-01-01

    ; and 3) Services of general interest. In the Blurring Boundaries project, three aspects of the European Social Model have been particularly highlighted: the constitutionalisation of the European Social Model, its multi-level legal character, and the clash between market access justice at EU level...... and distributive justice at national level....

  6. Regulation of biofilm formation and cellular buoyancy through modulating intracellular cyclic di-GMP levels in engineered cyanobacteria.

    Science.gov (United States)

    Agostoni, Marco; Waters, Christopher M; Montgomery, Beronda L

    2016-02-01

    The second messenger cyclic dimeric (3'→5') GMP (cyclic di-GMP or c-di-GMP) has been implicated in the transition between motile and sessile lifestyles in bacteria. In this study, we demonstrate that biofilm formation, cellular aggregation or flocculation, and cellular buoyancy are under the control of c-di-GMP in Synechocystis sp. PCC 6803 (Synechocystis) and Fremyella diplosiphon. Synechocystis is a unicellular cyanobacterium and displays lower levels of c-di-GMP; F. diplosiphon is filamentous and displays higher intracellular c-di-GMP levels. We transformed Synechocystis and F. diplosiphon with a plasmid for constitutive expression of genes encoding diguanylate cylase (DGC) and phosphodiesterase (PDE) proteins from Vibrio cholerae or Escherichia coli, respectively. These engineered strains allowed us to modulate intracellular c-di-GMP levels. Biofilm formation and cellular deposition were induced in the DGC-expressing Synechocystis strain which exhibited high intracellular levels of c-di-GMP; whereas strains expressing PDE in Synechocystis and F. diplosiphon to drive low intracellular levels of c-di-GMP exhibited enhanced cellular buoyancy. In addition, the PDE-expressing F. diplosiphon strain showed elevated chlorophyll levels. These results imply roles for coordinating c-di-GMP homeostasis in regulating native cyanobacterial phenotypes. Engineering exogenous DGC or PDE proteins to regulate intracellular c-di-GMP levels represents an effective tool for uncovering cryptic phenotypes or modulating phenotypes in cyanobacteria for practical applications in biotechnology applicable in photobioreactors and in green biotechnologies, such as energy-efficient harvesting of cellular biomass or the treatment of metal-containing wastewaters.

  7. The effects of formative assessment on student self-regulation, motivational beliefs, and achievement in elementary science

    Science.gov (United States)

    King, Melissa Digennaro

    Goals 2000 set forth a bold vision for U.S. students: they would be "first in the world in science and mathematics" by the year 2000. Performance indicators such as the TIMSS-R (1999) and NAEP (2000) reports suggest that U.S. students have not yet reached that goal. This study intended to learn how specific assessment strategies might contribute to improved student performance in science. This quasi-experimental study investigated the effects of formative assessment with reflection on students' motivational beliefs, self-regulatory skills, and achievement in elementary science. The study aimed to find out whether and how classroom applications of formative assessment during science instruction might influence fifth-grade students' attitudes and self-perceptions about science learning, self-regulatory learning behaviors, and achievement. To explore the effects of the assessment intervention, the study utilized a mixed methods approach involving quantitative and qualitative investigations of treatment and control groups during a four-week intervention period. Quantitative measures included student self-report surveys administered pre- and post-treatment and an end-of-unit science test. Qualitative measures included classroom observations, student interviews (post-treatment), and a teacher interview (post-treatment). Findings indicated that the fifth-grade students in this study had positive attitudes toward science and high levels of self-efficacy for science. Results suggested that these elementary students employed a wide variety of cognitive and metacognitive strategies to support science learning. Findings revealed that these fifth graders believed formative assessment with reflection was beneficial for science learning outcomes. Research results did not show that the formative assessment intervention contributed to significant differences between treatment and control groups. However, the data revealed different levels of academic achievement and self-regulation

  8. Kir2.1 regulates rat smooth muscle cell proliferation, migration, and post-injury carotid neointimal formation.

    Science.gov (United States)

    Qiao, Yong; Tang, Chengchun; Wang, Qingjie; Wang, Dong; Yan, Gaoliang; Zhu, Boqian

    2016-09-01

    Phenotype switching of vascular smooth muscle cells (VSMC) from the contractile type to the synthetic type is a hallmark of vascular disorders such as atherosclerosis and restenosis after angioplasty. Inward rectifier K(+) channel 2.1 (Kir2.1) has been identified in VSMC. However, whether it plays a functional role in regulating cellular transformation remains obscure. In this study, we evaluated the role of Kir2.1 on VSMC proliferation, migration, phenotype switching, and post-injury carotid neointimal formation. Kir2.1 knockdown significantly suppressed platelet-derived growth factor BB-stimulated rat vascular smooth muscle cells (rat-VSMC) proliferation and migration. Deficiency in Kir2.1 contributed to the restoration of smooth muscle α-actin, smooth muscle 22α, and calponin and to a reduction in osteopontin expression in rat-VSMC. Moreover, the in vivo study showed that rat-VSMC switched to proliferative phenotypes and that knockdown of Kir2.1 significantly inhibited neointimal formation after rat carotid injury. Kir2.1 may be a potential therapeutic target in the treatment of cardiovascular diseases, such as atherosclerosis and restenosis following percutaneous coronary intervention. PMID:27387235

  9. Vertical Equilibrium, Energetics, and Star Formation Rates in Magnetized Galactic Disks Regulated by Momentum Feedback from Supernovae

    CERN Document Server

    Kim, Chang-Goo

    2015-01-01

    Recent hydrodynamic (HD) simulations have shown that galactic disks evolve to reach well-defined statistical equilibrium states. The star formation rate (SFR) self-regulates until energy injection by star formation feedback balances dissipation and cooling in the interstellar medium (ISM), and provides vertical pressure support to balance gravity. In this paper, we extend our previous models to allow for a range of initial magnetic field strengths and configurations, utilizing three-dimensional, magnetohydrodynamic (MHD) simulations. We show that a quasi-steady equilibrium state is established as rapidly for MHD as for HD models unless the initial magnetic field is very strong or very weak, which requires more time to reach saturation. Remarkably, models with initial magnetic energy varying by two orders of magnitude approach the same asymptotic state. In the fully saturated state of the fiducial model, the integrated energy proportions E_kin:E_th:E_mag,t:E_mag,o are 0.35:0.39:0.15:0.11, while the proportions...

  10. FAM83H and casein kinase I regulate the organization of the keratin cytoskeleton and formation of desmosomes

    Science.gov (United States)

    Kuga, Takahisa; Sasaki, Mitsuho; Mikami, Toshinari; Miake, Yasuo; Adachi, Jun; Shimizu, Maiko; Saito, Youhei; Koura, Minako; Takeda, Yasunori; Matsuda, Junichiro; Tomonaga, Takeshi; Nakayama, Yuji

    2016-01-01

    FAM83H is essential for the formation of dental enamel because a mutation in the FAM83H gene causes amelogenesis imperfecta (AI). We previously reported that the overexpression of FAM83H often occurs and disorganizes the keratin cytoskeleton in colorectal cancer cells. We herein show that FAM83H regulates the organization of the keratin cytoskeleton and maintains the formation of desmosomes in ameloblastoma cells. FAM83H is expressed and localized on keratin filaments in human ameloblastoma cell lines and in mouse ameloblasts and epidermal germinative cells in vivo. FAM83H shows preferential localization to keratin filaments around the nucleus that often extend to cell-cell junctions. Alterations in the function of FAM83H by its overexpression, knockdown, or an AI-causing truncated mutant prevent the proper organization of the keratin cytoskeleton in ameloblastoma cells. Furthermore, the AI-causing mutant prevents desmosomal proteins from being localized to cell-cell junctions. The effects of the AI-causing mutant depend on its binding to and possible inhibition of casein kinase I (CK-1). The suppression of CK-1 by its inhibitor, D4476, disorganizes the keratin cytoskeleton. Our results suggest that AI caused by the FAM83H mutation is mediated by the disorganization of the keratin cytoskeleton and subsequent disruption of desmosomes in ameloblasts. PMID:27222304

  11. MEG3 long noncoding RNA regulates the TGF-β pathway genes through formation of RNA-DNA triplex structures.

    Science.gov (United States)

    Mondal, Tanmoy; Subhash, Santhilal; Vaid, Roshan; Enroth, Stefan; Uday, Sireesha; Reinius, Björn; Mitra, Sanhita; Mohammed, Arif; James, Alva Rani; Hoberg, Emily; Moustakas, Aristidis; Gyllensten, Ulf; Jones, Steven J M; Gustafsson, Claes M; Sims, Andrew H; Westerlund, Fredrik; Gorab, Eduardo; Kanduri, Chandrasekhar

    2015-01-01

    Long noncoding RNAs (lncRNAs) regulate gene expression by association with chromatin, but how they target chromatin remains poorly understood. We have used chromatin RNA immunoprecipitation-coupled high-throughput sequencing to identify 276 lncRNAs enriched in repressive chromatin from breast cancer cells. Using one of the chromatin-interacting lncRNAs, MEG3, we explore the mechanisms by which lncRNAs target chromatin. Here we show that MEG3 and EZH2 share common target genes, including the TGF-β pathway genes. Genome-wide mapping of MEG3 binding sites reveals that MEG3 modulates the activity of TGF-β genes by binding to distal regulatory elements. MEG3 binding sites have GA-rich sequences, which guide MEG3 to the chromatin through RNA-DNA triplex formation. We have found that RNA-DNA triplex structures are widespread and are present over the MEG3 binding sites associated with the TGF-β pathway genes. Our findings suggest that RNA-DNA triplex formation could be a general characteristic of target gene recognition by the chromatin-interacting lncRNAs. PMID:26205790

  12. The bifunctional abiotic stress signalling regulator and endogenous RNA silencing suppressor FIERY1 is required for lateral root formation

    KAUST Repository

    Chen, Hao

    2010-09-28

    The Arabidopsis FIERY1 (FRY1) locus was originally identified as a negative regulator of stress-responsive gene expression and later shown to be required for suppression of RNA silencing. In this study we discovered that the FRY1 locus also regulates lateral root formation. Compared with the wild type, fry1 mutant seedlings generated significantly fewer lateral roots under normal growth conditions and also exhibited a dramatically reduced sensitivity to auxin in inducing lateral root initiation. Using transgenic plants that overexpress a yeast homolog of FRY1 that possesses only the 3\\', 5\\'-bisphosphate nucleotidase activity but not the inositol 1-phosphatase activity, we demonstrated that the lateral root phenotypes in fry1 result from loss of the nucleotidase activity. Furthermore, a T-DNA insertion mutant of another RNA silencing suppressor, XRN4 (but not XRN2 or XRN3), which is an exoribonuclease that is inhibited by the substrate of the FRY1 3\\', 5\\'-bisphosphate nucleotidase, exhibits similar lateral root defects. Although fry1 and xrn4 exhibited reduced sensitivity to ethylene, our experiments demonstrated that restoration of ethylene sensitivity in the fry1 mutant is not sufficient to rescue the lateral root phenotypes of fry1. Our results indicate that RNA silencing modulated by FRY1 and XRN4 plays an important role in shaping root architecture. © 2010 Blackwell Publishing Ltd.

  13. Effect of growth regulator Kelpak SL on the formation of aboveground biomass of Festulolium braunii (K. Richt. A. Camus

    Directory of Open Access Journals (Sweden)

    Jacek Sosnowski

    2013-07-01

    Full Text Available A study on the cultivation of Festulolium braunii cv. 'Felopa' was carried out using polyurethane rings with a diameter of 36 cm and a height of 40 cm, which were sunk into the ground to a depth of 30 cm and filled with soil material. In this experiment, Kelpak SL was used as a bioregulator. It consists of natural plant hormones such as auxins (11 mg in dm3 and cytokinins (0.03 mg in dm3. The experimental factors were as follows: A1-control; A2 – 20% solution of the growth regulator; A3 – 40% solution; and A4 – 60% solution. The preparation was applied to all three regrowths in the form of spray, at a rate of 3 cm3 ring-1, at the stem elongation stage. The full period of this experiment was in the years 2010–2011. During this time, detailed investigations were carried out on aboveground biomass yield (g DM ring-1, number of shoots (pcs ring-1, leaf blade length (cm, width of the leaf blade base (mm, leaf greenness index (SPAD. The study showed a significant effect of the growth regulator on the formation of Festulolium braunii biomass. However, its highest effectiveness was observed when the 60% solution was applied.

  14. S1P-Yap1 signaling regulates endoderm formation required for cardiac precursor cell migration in zebrafish.

    Science.gov (United States)

    Fukui, Hajime; Terai, Kenta; Nakajima, Hiroyuki; Chiba, Ayano; Fukuhara, Shigetomo; Mochizuki, Naoki

    2014-10-13

    To form the primary heart tube in zebrafish, bilateral cardiac precursor cells (CPCs) migrate toward the midline beneath the endoderm. Mutants lacking endoderm and fish with defective sphingosine 1-phosphate (S1P) signaling exhibit cardia bifida. Endoderm defects lead to the lack of foothold for the CPCs, whereas the cause of cardia bifida in S1P signaling mutants remains unclear. Here we show that S1P signaling regulates CPC migration through Yes-associated protein 1 (Yap1)-dependent endoderm survival. Cardia bifida seen in spns2 (S1P transporter) morphants and s1pr2 (S1P receptor-2) morphants could be rescued by endodermal expression of nuclear localized form of yap1. yap1 morphants had decreased expression of the Yap1/Tead target connective tissue growth factor a (Ctgfa) and consequently increased endodermal cell apoptosis. Consistently, ctgfa morphants showed defects of the endodermal sheet and cardia bifida. Collectively, we show that S1pr2/Yap1-regulated ctgfa expression is essential for the proper endoderm formation required for CPC migration.

  15. Transcription Factors Efg1 and Bcr1 Regulate Biofilm Formation and Virulence during Candida albicans-Associated Denture Stomatitis.

    Science.gov (United States)

    Yano, Junko; Yu, Alika; Fidel, Paul L; Noverr, Mairi C

    2016-01-01

    Denture stomatitis (DS) is characterized by inflammation of the oral mucosa in direct contact with dentures and affects a significant number of otherwise healthy denture wearers. The disease is caused by Candida albicans, which readily colonizes and form biofilms on denture materials. While evidence for biofilms on abiotic and biotic surfaces initiating Candida infections is accumulating, a role for biofilms in DS remains unclear. Using an established model of DS in immunocompetent animals, the purpose of this study was to determine the role of biofilm formation in mucosal damage during pathogenesis using C. albicans or mutants defective in morphogenesis (efg1-/-) or biofilm formation (bcr1-/-). For in vivo analyses, rats fitted with custom dentures, consisting of fixed and removable parts, were inoculated with wild-type C. albicans, mutants or reconstituted strains and monitored weekly for fungal burden (denture and palate), body weight and tissue damage (LDH) for up to 8 weeks. C. albicans wild-type and reconstituted mutants formed biofilms on dentures and palatal tissues under in vitro, ex vivo and in vivo conditions as indicated by microscopy demonstrating robust biofilm architecture and extracellular matrix (ECM). In contrast, both efg1-/- and bcr1-/- mutants exhibited poor biofilm growth with little to no ECM. In addition, quantification of fungal burden showed reduced colonization throughout the infection period on dentures and palates of rats inoculated with efg1-/-, but not bcr1-/-, compared to controls. Finally, rats inoculated with efg1-/- and bcr1-/- mutants had minimal palatal tissue damage/weight loss while those inoculated with wild-type or reconstituted mutants showed evidence of tissue damage and exhibited stunted weight gain. These data suggest that biofilm formation is associated with tissue damage during DS and that Efg1 and Bcr1, both central regulators of virulence in C. albicans, have pivotal roles in pathogenesis of DS.

  16. The Self-Made Puzzle: Integrating Self-Assembly and Pattern Formation Under Non-Random Genetic Regulation

    Science.gov (United States)

    Doursat, René

    On the one hand, research in self-assembling systems, whether natural or artificial, has traditionally focused on pre-existing components endowed with fixed shapes. Biological development, by contrast, dynamically creates new cells that acquire selective adhesion properties through differentiation induced by their neighborhood. On the other hand, pattern formation phenomena are generally construed as orderly states of activity on top of a continuous 2-D or 3-D substrate. Yet, again, the spontaneous patterning of an organism into domains of gene expression arises within a multicellular medium in perpetual expansion and reshaping. Finally, both phenomena are often thought in terms of stochastic events, whether mixed components that randomly collide in self-assembly, or spots and stripes that occur unpredictably from instabilities in pattern formation. Here too, these notions need significant revision if they are to be extended and applied to embryogenesis. Cells are not randomly mixed but pre-positioned where cell division occurs. Genetic identity domains are not randomly distributed but highly regulated in number and position. In this work, I present a computational model of program-mable and reproducible artificial morphogenesis that integrates self-assembly and pattern formation under the control of a nonrandom gene regulatory network. The specialized properties of cells (division, adhesion, migration) are determined by the gene expression domains to which they belong, while at the same time these domains further expand and segment into subdomains due to the self-assembly of specialized cells. Through this model, I also promote a new discipline, embryomorphic engineering to solve the paradox of "meta-designing" decentralized, autonomous systems.

  17. Transcription Factors Efg1 and Bcr1 Regulate Biofilm Formation and Virulence during Candida albicans-Associated Denture Stomatitis.

    Directory of Open Access Journals (Sweden)

    Junko Yano

    Full Text Available Denture stomatitis (DS is characterized by inflammation of the oral mucosa in direct contact with dentures and affects a significant number of otherwise healthy denture wearers. The disease is caused by Candida albicans, which readily colonizes and form biofilms on denture materials. While evidence for biofilms on abiotic and biotic surfaces initiating Candida infections is accumulating, a role for biofilms in DS remains unclear. Using an established model of DS in immunocompetent animals, the purpose of this study was to determine the role of biofilm formation in mucosal damage during pathogenesis using C. albicans or mutants defective in morphogenesis (efg1-/- or biofilm formation (bcr1-/-. For in vivo analyses, rats fitted with custom dentures, consisting of fixed and removable parts, were inoculated with wild-type C. albicans, mutants or reconstituted strains and monitored weekly for fungal burden (denture and palate, body weight and tissue damage (LDH for up to 8 weeks. C. albicans wild-type and reconstituted mutants formed biofilms on dentures and palatal tissues under in vitro, ex vivo and in vivo conditions as indicated by microscopy demonstrating robust biofilm architecture and extracellular matrix (ECM. In contrast, both efg1-/- and bcr1-/- mutants exhibited poor biofilm growth with little to no ECM. In addition, quantification of fungal burden showed reduced colonization throughout the infection period on dentures and palates of rats inoculated with efg1-/-, but not bcr1-/-, compared to controls. Finally, rats inoculated with efg1-/- and bcr1-/- mutants had minimal palatal tissue damage/weight loss while those inoculated with wild-type or reconstituted mutants showed evidence of tissue damage and exhibited stunted weight gain. These data suggest that biofilm formation is associated with tissue damage during DS and that Efg1 and Bcr1, both central regulators of virulence in C. albicans, have pivotal roles in pathogenesis of DS.

  18. SEUSS Integrates Gibberellin Signaling with Transcriptional Inputs from the SHR-SCR-SCL3 Module to Regulate Middle Cortex Formation in the Arabidopsis Root.

    Science.gov (United States)

    Gong, Xue; Flores-Vergara, Miguel A; Hong, Jing Han; Chu, Huangwei; Lim, Jun; Franks, Robert G; Liu, Zhongchi; Xu, Jian

    2016-03-01

    A decade of studies on middle cortex (MC) formation in the root endodermis of Arabidopsis (Arabidopsis thaliana) have revealed a complex regulatory network that is orchestrated by several GRAS family transcription factors, including SHORT-ROOT (SHR), SCARECROW (SCR), and SCARECROW-LIKE3 (SCL3). However, how their functions are regulated remains obscure. Here we show that mutations in the SEUSS (SEU) gene led to a higher frequency of MC formation. seu mutants had strongly reduced expression of SHR, SCR, and SCL3, suggesting that SEU positively regulates these genes. Our results further indicate that SEU physically associates with upstream regulatory sequences of SHR, SCR, and SCL3; and that SEU has distinct genetic interactions with these genes in the control of MC formation, with SCL3 being epistatic to SEU. Similar to SCL3, SEU was repressed by the phytohormone GA and induced by the GA biosynthesis inhibitor paclobutrazol, suggesting that SEU acts downstream of GA signaling to regulate MC formation. Consistently, we found that SEU mediates the regulation of SCL3 by GA signaling. Together, our study identifies SEU as a new critical player that integrates GA signaling with transcriptional inputs from the SHR-SCR-SCL3 module to regulate MC formation in the Arabidopsis root.

  19. Heme oxygenase-1 regulates the major route involved in formation of immune hepatic fibrosis in rats

    Institute of Scientific and Technical Information of China (English)

    DUAN Zhi-jun; YANG Dong; WANG Fei; SUN Ying-jie; SUN Xiao-yu; ZHENG Miao-lei

    2010-01-01

    Background Heme oxygenase (HO) plays roles in some liver diseases, but what it does in immune liver fibrosis is rarely reported. We investigated the regulation mechanisms of HO-1 in rat immune liver fibrosis to find routes for intervention.Methods Male Sprague-Dawley rats were randomly divided into control group (N, n=12), fibrosis group (F, n=20),cobalt protoporphyrin (CoPP) inducing group (Co, n=20) and zinc protoporphyrin (ZnPP) inhibiting group (Zn, n=20). In groups F, Co and Zn, immune liver fibrosis was established with human serum albumin. At the attacked stage, CoPP (5mg/kg) and ZnPP (5 mg/kg) were intraperitoneally injected in groups Co and Zn, respectively. After establishment of rat models, the numbers of rats reduced to 11, 15, 17 and 12 in groups N, F, Co and Zn respectively, because of death during the process. HO-1 in liver was detected by Westem blotting and immunohistochemistry. The indexes of fibrosis were assessed by radioimmunoassay. Concentrations of serum transforming growth factor-β1 (TGF-β1), and tissue inhibitor of metalloproteinses (TIMP-1) were detected using enzyme-linked immunosorbent assay. Hepatic stellate cell (HSC) and proliferation degree of fibrosis were assessed by pathological examination. Data analysis was performed by SPSS 10.0software.Results The expression of HO-1 in group F was significantly higher than that in group N, but lower than that in group Co (P <0.05); while that in group Zn was lower than in group F (P <0.05), but still higher than that in group N (P <0.01).Compared with group N, liver functional and liver fibrosis indicators were increased in group F (P <0.01), while comparing to group F, they were decreased in group Co (P <0.05) and increased in group Zn (P <0.05). CoPP reduced the extent of hepatocellular injury and hepatic fibrosis in comparison with group F (P <0.01), being the opposite effect of ZnPP (P<0.01). HSC was observed using indirect method and the result showed that the number of

  20. Cyclophilin E functions as a negative regulator to influenza virus replication by impairing the formation of the viral ribonucleoprotein complex.

    Directory of Open Access Journals (Sweden)

    Zengfu Wang

    Full Text Available BACKGROUND: The nucleoprotein (NP of influenza A virus is a multifunctional protein that plays a critical role in the replication and transcription of the viral genome. Therefore, examining host factors that interact with NP may shed light on the mechanism of host restriction barriers and the tissue tropism of influenza A virus. Here, Cyclophilin E (CypE, a member of the peptidyl-propyl cis-trans isomerase (PPIase family, was found to bind to NP and inhibit viral replication and transcription. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, CypE was found to interact with NP but not with the other components of the viral ribonucleoprotein complex (VRNP: PB1, PB2, and PA. Mutagenesis data revealed that the CypE domain comprised of residues 137-186 is responsible for its binding to NP. Functional analysis results indicated that CypE is a negative regulator in the influenza virus life cycle. Furthermore, knock-down of CypE resulted in increased levels of three types of viral RNA, suggesting that CypE negatively affects viral replication and transcription. Moreover, up-regulation of CypE inhibited the activity of influenza viral polymerase. We determined that the molecular mechanism by which CypE negatively regulates influenza virus replication and transcription is by interfering with NP self-association and the NP-PB1 and NP-PB2 interactions. CONCLUSIONS/SIGNIFICANCE: CypE is a host restriction factor that inhibits the functions of NP, as well as viral replication and transcription, by impairing the formation of the vRNP. The data presented here will help us to better understand the molecular mechanisms of host restriction barriers, host adaptation, and tissue tropism of influenza A virus.

  1. Beta- lactam antibiotics stimulate biofilm formation in non-typeable haemophilus influenzae by up-regulating carbohydrate metabolism.

    Directory of Open Access Journals (Sweden)

    Siva Wu

    Full Text Available Non-typeable Haemophilus influenzae (NTHi is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10 µg/mL of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended.

  2. Promyelocytic Leukemia Protein (PML) Regulates Endothelial Cell Network Formation and Migration in Response to Tumor Necrosis Factor α (TNFα) and Interferon α (IFNα)*

    Science.gov (United States)

    Cheng, Xiwen; Liu, Yu; Chu, Hao; Kao, Hung-Ying

    2012-01-01

    Promyelocytic leukemia protein (PML) is a tumor suppressor that is highly expressed in vascular endothelium and inflamed tissues, yet its role in inflammation-associated cytokine-regulated angiogenesis and underlying mechanism remains largely unclear. We show that tumor necrosis factor α (TNFα) and interferon α (IFNα) stimulate PML expression while suppressing EC network formation and migration, two key events during angiogenesis. By a knockdown approach, we demonstrate that PML is indispensable for TNFα- and IFNα-mediated inhibition of EC network formation. We further demonstrate that signal transducer and activator of transcription 1 (STAT1) binds PML promoter and that is an important regulator of PML expression. Knockdown of STAT1 reduces endogenous PML and blocks TNFα- and IFNα-induced PML accumulation and relieves TNFα- and IFNα-mediated inhibition of EC network formation. Our data also indicate that PML regulates EC migration, in part, by modulating expression of downstream genes, such as negatively regulating integrin β1 (ITGB1). In addition, knockdown of STAT1 or PML alleviates TNFα- and IFNα-mediated inhibition of ITGB1 expression. Antibody blockade demonstrates that ITGB1 is functionally important for PML- and STAT1-regulated EC migration. Taken together, our data provide novel mechanistic insights that PML functions as a negative regulator in EC network formation and migration. PMID:22589541

  3. Boundary issues

    Science.gov (United States)

    Townsend, Alan R.; Porder, Stephen

    2011-03-01

    What is our point of no return? Caesar proclaimed 'the die is cast' while crossing the Rubicon, but rarely does modern society find so visible a threshold in our continued degradation of ecosystems and the services they provide. Humans have always used their surroundings to make a living— sometimes successfully, sometimes not (Diamond 2005)—and we intuitively know that there are boundaries to our exploitation. But defining these boundaries has been a challenge since Malthus first prophesied that nature would limit the human population (Malthus 1798). In 2009, Rockström and colleagues tried to quantify what the 6.8 billion (and counting) of us could continue to get away with, and what we couldn't (Rockström et al 2009). In selecting ten 'planetary boundaries', the authors contend that a sustainable human enterprise requires treating a number of environmental thresholds as points of no return. They suggest we breach these Rubicons at our own peril, and that we've already crossed three: biodiversity loss, atmospheric CO2, and disruption of the global nitrogen (N) cycle. As they clearly hoped, the very act of setting targets has provoked scientific inquiry about their accuracy, and about the value of hard targets in the first place (Schlesinger 2009). Such debate is a good thing. Despite recent emphasis on the science of human-ecosystem interactions, understanding of our planetary boundaries is still in its infancy, and controversy can speed scientific progress (Engelhardt and Caplan 1987). A few weeks ago in this journal, Carpenter and Bennett (2011) took aim at one of the more controversial boundaries in the Rockström analysis: that for human alteration of the global phosphorus (P) cycle. Rockström's group chose riverine P export as the key indicator, suggesting that humans should not exceed a value that could trigger widespread marine anoxic events—and asserting that we have not yet crossed this threshold. There are defensible reasons for a marine

  4. Albedo Boundary

    Science.gov (United States)

    2003-01-01

    MGS MOC Release No. MOC2-510, 11 October 2003The sharp, nearly straight line that runs diagonally across the center of this April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an albedo boundary. Albedois a term that refers to reflectance of sunlight. A surface with a low albedo is one that appears dark because it reflects less light than a high albedo (bright) surface. On Mars, albedo boundaries occur between two materials of differing texture, particle size, or composition, or some combination of these three factors. The boundary shown here is remarkable because it is so sharp and straight. This is caused by wind. Most likely, the entire surface was once covered with the lower-albedo (darker) material that is now seen in the upper half of the image. At some later time, wind stripped away this darker material from the surfaces in the lower half of the image. The difference in albedo here might be related to composition, and possibly particle size. This picture is located near the southwest rim of Schiaparelli Basin at 5.5oS, 345.9oW. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.

  5. sarA negatively regulates Staphylococcus epidermidis biofilm formation by modulating expression of 1 MDa extracellular matrix binding protein and autolysis‐dependent release of eDNA

    DEFF Research Database (Denmark)

    Christner, Martin; Heinze, Constanze; Busch, Michael;

    2012-01-01

    Biofilm formation is essential for Staphylococcus epidermidis pathogenicity in implant‐associated infections. Nonetheless, large proportions of invasive Staphylococcus epidermidis isolates fail to form a biofilm in vitro. We here tested the hypothesis that this apparent paradox is related...... to the existence of superimposed regulatory systems suppressing a multicellular biofilm life style in vitro. Transposon mutagenesis of clinical significant but biofilm‐negative S. epidermidis 1585 was used to isolate a biofilm positive mutant carrying a Tn917 insertion in sarA, chief regulator of staphylococcal......DNA‐dependent biofilm formation. Given the importance of SarA as a positive regulator of polysaccharide mediated cell aggregation, the regulator enables S. epidermidis to switch between mechanisms of biofilm formation, ensuring S. epidermidis adaptation to hostile environments....

  6. Deposition and alteration of carbonaceous series within a Neotethyan rift at the western boundary of the Arabian plate: The late Permian Um Irna Formation, NW Jordan, a petroleum system

    Energy Technology Data Exchange (ETDEWEB)

    Dill, H.G.; Kus, J. [Federal Institute for Geosciences and Natural Resources, P.O. Box 51 01 53 D-30631 Hannover (Germany); Bechtel, A.; Gratzer, R. [Department of Applied Geosciences and Geophysics, University of Leoben, Peter Tunner Strasse 5, A-8700 Leoben (Austria); Abu Hamad, A.M.B. [Geology Department, University of Jordan, Amman 11942 (Jordan)

    2010-01-07

    During the late Permian (Kungurian to Kazanian) a Neotethyan rift basin evolved at the western boundary of the Arabian Plate, in what is called today the Dead Sea Valley of western Jordan. The break-up of Pangaea was accompanied by low-sinuosity sandy braided- to meandering-fluvial drainage systems which were fed by the uplift of the Arabian Shield and by poorly aerated swamps and ponds that concentrated plant debris of the Cathaysian floral province in the Um Irna Formation. These proximal wet fan sediments are overlain by a dry fan characterized by extensive reddish floodplain deposits, anastomosing channel systems and paleosols. The wet fan is underlain by Cambrian sandstones. These units serve as the top and bottom seals of the OM-bearing system of the Um Irna Formation. The sedimentary rocks of the OM-bearing Um Irna Formation underwent supergene, diagenetic and epigenetic hydrothermal alteration under an elevated geothermal gradient. The temperature increased from the time of deposition of the wet to the time of deposition of the dry fan and caused remobilization of manganese already pre-concentrated in the Cambrian footwall rocks of the rift basin. The anomalous heat regime may be accounted for as a predecessor stage of the Dead Sea Rift which is still active today. Oil seeps are found along faults and fractures near this deep-seated lineamentary fault zone. The deposition and alteration of the organic matter in this late Permian rift are of great consequence for oil generation in the region. Organic petrographic investigations revealed that organic-rich terrestrial carbonaceous and coal rich sediments of mainly of type III kerogen are dominant in the Um Irna Formation. In addition, aquatic liptinite rich sedimentary input (fresh water lake and/or lacustrine swamp) of type I kerogen is also noted. Coal derived organic matter occurs in the form of coaly particles with ranks from subbituminous A to high volatile bituminous C. Higher plant-derived macerals as

  7. The Mitogen-Activated Protein Kinase Kinase VdPbs2 of Verticillium dahliae Regulates Microsclerotia Formation, Stress Response, and Plant Infection

    Science.gov (United States)

    Tian, Longyan; Wang, Yonglin; Yu, Jun; Xiong, Dianguang; Zhao, Hengjun; Tian, Chengming

    2016-01-01

    Verticillium dahliae, a ubiquitous phytopathogenic fungus, forms resting structures, known as microsclerotia that play crucial roles in Verticillium wilt diseases. VdHog1, a mitogen-activated protein kinase (MAPK), controls microsclerotia formation, virulence, and stress response in V. dahliae. In this study, we present detailed evidence that the conserved upstream component of VdHog1, VdPbs2, is a key regulator of microsclerotia formation, oxidative stress and fungicide response and plant virulence in V. dahliae. We identified VdPbs2, homologous to the yeast MAPK kinase Pbs2. Similar to the VdHog1 deletion mutant, VdPbs2 deletion strains exhibited delayed melanin synthesis and reduced formation of microsclerotia. When exposed to stresses, VdPbs2 mutants were more sensitive than the wild type to osmotic agents and peroxide, but more resistant to inhibitors of cell wall synthesis and some fungicides. Finally, VdPbs2 deletion mutants exhibited reduced virulence on smoke tree and tobacco seedlings. When taken together, we implicate that VdPbs2 and VdHog1 function in a cascade that regulates microsclerotia formation and virulence, but not all VdHog1 dependent functions are VdPbs2 regulated. This study thus provides novel insights into the signal transduction mechanisms that regulate microsclerotia formation and pathogenesis in this fungus. PMID:27729908

  8. Phosphatidylcholine formation by LPCAT1 is regulated by Ca2+ and the redox status of the cell

    Directory of Open Access Journals (Sweden)

    Soupene Eric

    2012-06-01

    Full Text Available Abstract Background Unsaturated fatty acids are susceptible to oxidation and damaged chains are removed from glycerophospholipids by phospholipase A2. De-acylated lipids are then re-acylated by lysophospholipid acyltransferase enzymes such as LPCAT1 which catalyses the formation of phosphatidylcholine (PC from lysoPC and long-chain acyl-CoA. Results Activity of LPCAT1 is inhibited by Ca2+, and a Ca2+-binding motif of the EF-hand type, EFh-1, was identified in the carboxyl-terminal domain of the protein. The residues Asp-392 and Glu-403 define the loop of the hairpin structure formed by EFh-1. Substitution of D392 and E403 to alanine rendered an enzyme insensitive to Ca2+, which established that Ca2+ binding to that region negatively regulates the activity of the acyltransferase amino-terminal domain. Residue Cys-211 of the conserved motif III is not essential for catalysis and not sufficient for sensitivity to treatment by sulfhydryl-modifier agents. Among the several active cysteine-substitution mutants of LPCAT1 generated, we identified one to be resistant to treatment by sulfhydryl-alkylating and sulfhydryl-oxidizer agents. Conclusion Mutant forms of LPCAT1 that are not inhibited by Ca2+ and sulfhydryl-alkylating and –oxidizing agents will provide a better understanding of the physiological function of a mechanism that places the formation of PC, and the disposal of the bioactive species lysoPC, under the control of the redox status and Ca2+ concentration of the cell.

  9. Late activation of the 9-oxylipin pathway during arbuscular mycorrhiza formation in tomato and its regulation by jasmonate signalling

    Science.gov (United States)

    León-Morcillo, Rafael Jorge; Ángel, José; Martín-Rodríguez; Vierheilig, Horst; Ocampo, Juan Antonio; García-Garrido, José Manuel

    2012-01-01

    The establishment of an arbuscular mycorrhizal (AM) symbiotic interaction is a successful strategy for the promotion of substantial plant growth, development, and fitness. Numerous studies have supported the hypothesis that plant hormones play an important role in the establishment of functional AM symbiosis. Particular attention has been devoted to jasmonic acid (JA) and its derivates, which are believed to play a major role in AM symbiosis. Jasmonates belong to a diverse class of lipid metabolites known as oxylipins that include other biologically active molecules. Recent transcriptional analyses revealed up-regulation of the oxylipin pathway during AM symbiosis in mycorrhizal tomato roots and indicate a key regulatory role for oxylipins during AM symbiosis in tomato, particularly those derived from the action of 9-lipoxygenases (9-LOXs). Continuing with the tomato as a model, the spatial and temporal expression pattern of genes involved in the 9-LOX pathway during the different stages of AM formation in tomato was analysed. The effects of JA signalling pathway changes on AM fungal colonization were assessed and correlated with the modifications in the transcriptional profiles of 9-LOX genes. The up-regulation of the 9-LOX oxylipin pathway in mycorrhizal wild-type roots seems to depend on a particular degree of AM fungal colonization and is restricted to the colonized part of the roots, suggesting that these genes could play a role in controlling fungal spread in roots. In addition, the results suggest that this strategy of the plant to control AM fungi development within the roots is at least partly dependent on JA pathway activation. PMID:22442425

  10. 川东北三叠系雷口坡组与须家河组界线微球粒的发现%The discovery of the micropellets from the Triassic Leikoupo Formation-Xujiahe Formation boundary in northeastern Sichuan

    Institute of Scientific and Technical Information of China (English)

    刘雁婷; 傅恒; 陈骥; 孙先长; 达丽亚; 刘欣; 孙利川; 岳文成

    2012-01-01

    The micropellets are recognized for the first time from the Triassic Leikoupo Formation-Xujiahe Formation boundary in northeastern Sichuan. These micropellets occur as single solid rounded pellets with the diameters from 3 to 4 μm, and compositionally they display the siliceous pellets in which the corrosion structures and textures are visible. It is probable that the meteorite-impact events once took place around the Triassic Leikoupo Formation-Xujiahe Formation boundary in northeastern Sichuan. The discovery of the micropellets in the study area may inspire some new approaches to fathom the terrestrial-marine transition and biotic succession during the Triassic in the Sichuan Basin.%在川东北地区三叠系雷口坡组与须家河组地层界线处首次发现微球粒.这些微球粒呈单球体,形状为实心圆球状,直径3~4μm.微球粒成分为硅质球,可见溶蚀结构,推测研究区在中、晚三叠世之交可能发生过陨击事件,为研究四川盆地三叠纪海陆演变、生物更替提供了一种新的研究思路.

  11. boundary dissipation

    Directory of Open Access Journals (Sweden)

    Mehmet Camurdan

    1998-01-01

    are coupled by appropriate trace operators. This overall model differs from those previously studied in the literature in that the elastic chamber floor is here more realistically modeled by a hyperbolic Kirchoff equation, rather than by a parabolic Euler-Bernoulli equation with Kelvin-Voight structural damping, as in past literature. Thus, the hyperbolic/parabolic coupled system of past literature is replaced here by a hyperbolic/hyperbolic coupled model. The main result of this paper is a uniform stabilization of the coupled PDE system by a (physically appealing boundary dissipation.

  12. CaMKII, but not protein kinase A, regulates Rpt6 phosphorylation and proteasome activity during the formation of long-term memories

    Directory of Open Access Journals (Sweden)

    Timothy J Jarome

    2013-08-01

    Full Text Available CaMKII and Protein Kinase A (PKA are thought to be critical for synaptic plasticity and memory formation through their regulation of protein synthesis. Consistent with this, numerous studies have reported that CaMKII, PKA and protein synthesis are critical for long-term memory formation. Recently, we found that protein degradation through the ubiquitin-proteasome system is also critical for long-term memory formation in the amygdala. However, the mechanism by which ubiquitin-proteasome activity is regulated during memory formation and how protein degradation interacts with known intracellular signaling pathways important for learning remain unknown. Recently, evidence has emerged suggesting that both CaMKII and PKA are capable of regulating proteasome activity in vitro through the phosphorylation of proteasome regulatory subunit Rpt6 at Serine-120, though whether they regulate Rpt6 phosphorylation and proteasome function in vivo remains unknown. In the present study we demonstrate for the first time that fear conditioning transiently modifies a proteasome regulatory subunit and proteasome catalytic activity in the mammalian brain in a CaMKII-dependent manner. We found increases in the phosphorylation of proteasome ATPase subunit Rpt6 at Serine-120 and an enhancement in proteasome activity in the amygdala following fear conditioning. Pharmacological manipulation of CaMKII, but not PKA, in vivo significantly reduced both the learning-induced increase in Rpt6 Serine-120 phosphorylation and the increase in proteasome activity without directly affecting protein polyubiquitination levels. These results indicate a novel role for CaMKII in memory formation through its regulation of protein degradation and suggest that CaMKII regulates Rpt6 phosphorylation and proteasome function both in vitro and in vivo.

  13. Single-droplet evaporation kinetics and particle formation in an acoustic levitator. Part 1: evaporation of water microdroplets assessed using boundary-layer and acoustic levitation theories.

    Science.gov (United States)

    Schiffter, Heiko; Lee, Geoffrey

    2007-09-01

    The suitability of a single droplet drying acoustic levitator as a model for the spray drying of aqueous, pharmaceutically-relevant solutes used to produce protein-loaded particles has been examined. The acoustic levitator was initially evaluated by measuring the drying rates of droplets of pure water in dependence of drying-air temperature and flow rate. The measured drying rates were higher than those predicted by boundary layer theory because of the effects of primary acoustic streaming. Sherwood numbers of 2.6, 3.6, and 4.4 at drying-air temperatures of 25 degrees C, 40 degrees C, and 60 degrees C were determined, respectively. Acoustic levitation theory could predict the measured drying rates and Sherwood numbers only when a forced-convection drying-air stream was used to neuralize the retarding effect of secondary acoustic streaming on evaporation rate. At still higher drying-air flow rates, the Ranz-Marshall correlation accurately predicts Sherwood number, provided a stable droplet position in the standing acoustic wave is maintained. The measured Sherwood numbers and droplet Reynolds numbers show that experiments performed in the levitator in still air are taking place effectively under conditions of substantial forced convection. The similitude of these values to those occurring in spray dryers is fortuitous for the suitability of the acoustic levitator as a droplet evaporation model for spray drying. PMID:17582811

  14. Definitive Endoderm Formation from Plucked Human Hair-Derived Induced Pluripotent Stem Cells and SK Channel Regulation

    Directory of Open Access Journals (Sweden)

    Anett Illing

    2013-01-01

    Full Text Available Pluripotent stem cells present an extraordinary powerful tool to investigate embryonic development in humans. Essentially, they provide a unique platform for dissecting the distinct mechanisms underlying pluripotency and subsequent lineage commitment. Modest information currently exists about the expression and the role of ion channels during human embryogenesis, organ development, and cell fate determination. Of note, small and intermediate conductance, calcium-activated potassium channels have been reported to modify stem cell behaviour and differentiation. These channels are broadly expressed throughout human tissues and are involved in various cellular processes, such as the after-hyperpolarization in excitable cells, and also in differentiation processes. To this end, human induced pluripotent stem cells (hiPSCs generated from plucked human hair keratinocytes have been exploited in vitro to recapitulate endoderm formation and, concomitantly, used to map the expression of the SK channel (SKCa subtypes over time. Thus, we report the successful generation of definitive endoderm from hiPSCs of ectodermal origin using a highly reproducible and robust differentiation system. Furthermore, we provide the first evidence that SKCas subtypes are dynamically regulated in the transition from a pluripotent stem cell to a more lineage restricted, endodermal progeny.

  15. Investigation of lead dendrite growth in the formation of valve-regulated lead-acid batteries for electric bicycle applications

    Science.gov (United States)

    Zeng, Yanzhen; Hu, Jingcheng; Ye, Wenmei; Zhao, Wenchao; Zhou, Gang; Guo, Yonglang

    2015-07-01

    The battery temperature, H2SO4 distribution, Pb2+ ion concentration and composition of the plates during the plate soaking of the 12 V 12 Ah valve-regulated lead-acid (VRLA) battery are studied. A simulated cell composed by two pure Pb plates and the absorptive glass mat (AGM) separator is used to investigate the growth of the lead dendrite in the separator, which is verified by analyzing the faulty batteries after the formation and the failure batteries after the usage. It is found that the H2SO4 is exhausted very quickly after filling and the separator near the plates can become neutral during soaking. Low acidity, high temperature and small PbSO4 particle size will increase the Pb2+ ion concentration. Higher Pb2+ ion concentration makes more PbSO4 tend to deposit on the coarse glass fibers, develop along them and even enwrap the entire fiber. And the fine PbSO4 crystals are continually transformed into large PbSO4 crystals via dissolution-deposition. In the subsequent charge, these PbSO4 crystals will be reduced to the club-shaped lead dendrites and may lead to short circuit of the battery.

  16. Enhanced expression of glucose-regulated protein 78 correlates with malondialdehyde levels during the formation of liver cirrhosis in rats

    Science.gov (United States)

    ZHANG, YUN; ZHANG, HUIYING; ZHAO, ZHONGFU; LV, MINLI; JIA, JIANTAO; ZHANG, LILI; TIAN, XIAOXIA; CHEN, YUNXIA; LI, BAOHONG; LIU, MINGSHE; HAN, DEWU; JI, CHENG

    2015-01-01

    The aim of the present study was to explore the role of glucose-regulated protein 78 (GRP78) in the development of liver cirrhosis promoted by intestinal endotoxemia in rats. Fifty-one male Wistar rats were randomly divided into the liver cirrhosis 4-week, 6-week and 8-week groups and the normal control group at each time point. Liver cirrhosis was induced by employing multiple pathogenic factors in the rats. Blood and liver tissues were collected. The levels of alanine aminotransferase (ALT), homocysteine, endotoxin and tumor necrosis factor-α (TNF-α) in the plasma, and TNF-α, malondialdehyde (MDA) and procollagen type III peptide (PIIIP) in the liver tissues were determined. The mRNA and protein expression levels of GRP78 in the liver were detected using reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. Morphological changes were observed through hematoxylin and eosin and van Gieson staining of the liver. Liver cirrhosis caused marked histopathological changes to the livers of the rats. Following significant increases in the levels of ALT, homocysteine, endotoxin and TNF-α in the plasma, and TNF-α, MDA and PIIIP in the liver tissues of all experimental groups with the progression of liver cirrhosis, the mRNA and protein expression levels of GRP78 also gradually increased. In addition, correlation analysis indicated that the enhanced expression of GRP78 correlated with the MDA levels of the rats during the formation of liver cirrhosis. PMID:26668603

  17. SNW1 is a critical regulator of spatial BMP activity, neural plate border formation, and neural crest specification in vertebrate embryos.

    Directory of Open Access Journals (Sweden)

    Mary Y Wu

    Full Text Available Bone morphogenetic protein (BMP gradients provide positional information to direct cell fate specification, such as patterning of the vertebrate ectoderm into neural, neural crest, and epidermal tissues, with precise borders segregating these domains. However, little is known about how BMP activity is regulated spatially and temporally during vertebrate development to contribute to embryonic patterning, and more specifically to neural crest formation. Through a large-scale in vivo functional screen in Xenopus for neural crest fate, we identified an essential regulator of BMP activity, SNW1. SNW1 is a nuclear protein known to regulate gene expression. Using antisense morpholinos to deplete SNW1 protein in both Xenopus and zebrafish embryos, we demonstrate that dorsally expressed SNW1 is required for neural crest specification, and this is independent of mesoderm formation and gastrulation morphogenetic movements. By exploiting a combination of immunostaining for phosphorylated Smad1 in Xenopus embryos and a BMP-dependent reporter transgenic zebrafish line, we show that SNW1 regulates a specific domain of BMP activity in the dorsal ectoderm at the neural plate border at post-gastrula stages. We use double in situ hybridizations and immunofluorescence to show how this domain of BMP activity is spatially positioned relative to the neural crest domain and that of SNW1 expression. Further in vivo and in vitro assays using cell culture and tissue explants allow us to conclude that SNW1 acts upstream of the BMP receptors. Finally, we show that the requirement of SNW1 for neural crest specification is through its ability to regulate BMP activity, as we demonstrate that targeted overexpression of BMP to the neural plate border is sufficient to restore neural crest formation in Xenopus SNW1 morphants. We conclude that through its ability to regulate a specific domain of BMP activity in the vertebrate embryo, SNW1 is a critical regulator of neural plate

  18. The contribution of sulphuric acid to atmospheric particle formation and growth: a comparison between boundary layers in Northern and Central Europe

    Directory of Open Access Journals (Sweden)

    V. Fiedler

    2005-01-01

    Full Text Available Atmospheric gaseous sulphuric acid was measured and its influence on particle formation and growth was investigated building on aerosol data. The measurements were part of the EU-project QUEST and took place at two different measurement sites in Northern and Central Europe (Hyytiälä, Finland, March-April 2003 and Heidelberg, Germany, March-April 2004. From a comprehensive data set including sulphuric acid, particle number size distributions and meteorological data, particle growth rates, particle formation rates and source rates of condensable vapors were inferred. Growth rates were determined in two different ways, from particle size distributions as well as from a so-called timeshift analysis. Moreover, correlations between sulphuric acid and particle number concentration between 3 and 6 nm were examined and the influence of air masses of different origin was investigated. Measured maximum concentrations of sulphuric acid were in the range from 1x106 to 16x106cm-3. The gaseous sulphuric acid lifetime with respect to condensation on aerosol particles ranged from 2 to 33min in Hyytiälä and from 0.5 to 8 min in Heidelberg. Most calculated values (growth rates, formation rates, vapor source rates were considerably higher in Central Europe (Heidelberg, due to the more polluted air and higher preexistent aerosol concentrations. Close correlations between H2SO4 and nucleation mode particles (size range: 3-6 nm were found on most days at both sites. The percentage contribution of sulphuric acid to particle growth was below 10% at both places and to initial growth below 20%. An air mass analysis indicated that at Heidelberg new particles were formed predominantly in air advected from southwesterly directions.

  19. Bacillus cereus ATCC 14579 RpoN (Sigma 54) is a Pleiotropic Regulator of Growth, Carbohydrate, Metabolism, Motility, Biofilm Formation and Toxin Production

    NARCIS (Netherlands)

    Hayrapetyan, H.; Tempelaars, M.H.; Nierop Groot, M.N.; Abee, T.

    2015-01-01

    Sigma 54 is a transcriptional regulator predicted to play a role in physical interaction of bacteria with their environment, including virulence and biofilm formation. In order to study the role of Sigma 54 in Bacillus cereus, a comparative transcriptome and phenotypic study was performed using B. c

  20. Hints of the early Jehol Biota: important dinosaur footprint assemblages from the Jurassic-Cretaceous boundary Tuchengzi Formation in Beijing, China.

    Science.gov (United States)

    Xing, Lida; Zhang, Jianping; Lockley, Martin G; McCrea, Richard T; Klein, Hendrik; Alcalá, Luis; Buckley, Lisa G; Burns, Michael E; Kümmell, Susanna B; He, Qing

    2015-01-01

    New reports of dinosaur tracksites in the Tuchengzi Formation in the newly established Yanqing Global Geopark, Beijing, China, support previous inferences that the track assemblages from this formation are saurischian-dominated. More specifically, the assemblages appear theropod-dominated, with the majority of well-preserved tracks conforming to the Grallator type (sensus lato), thus representing relatively small trackmakers. Such ichnofaunas supplement the skeletal record from this unit that lacks theropods thus far, proving a larger diversity of dinosaur faunas in that region. Sauropods are represented by medium to large sized and narrow and wide-gauge groups, respectively. The latter correspond with earlier discoveries of titanosauriform skeletons in the same unit. Previous records of ornithischian tracks cannot be positively confirmed. Purported occurrences are re-evaluated here, the trackways and imprints, except of a single possible specimen, re-assigned to theropods. Palecologically the Tuchengzi ichnofauna is characteristic of semi-arid fluvio-lacustrine inland basins with Upper Jurassic-Lower Cretaceous deposits in northern China that all show assemblages with abundant theropod and sauropod tracks and minor components of ornithopod, pterosaur and bird tracks.

  1. Hints of the early Jehol Biota: important dinosaur footprint assemblages from the Jurassic-Cretaceous boundary Tuchengzi Formation in Beijing, China.

    Directory of Open Access Journals (Sweden)

    Lida Xing

    Full Text Available New reports of dinosaur tracksites in the Tuchengzi Formation in the newly established Yanqing Global Geopark, Beijing, China, support previous inferences that the track assemblages from this formation are saurischian-dominated. More specifically, the assemblages appear theropod-dominated, with the majority of well-preserved tracks conforming to the Grallator type (sensus lato, thus representing relatively small trackmakers. Such ichnofaunas supplement the skeletal record from this unit that lacks theropods thus far, proving a larger diversity of dinosaur faunas in that region. Sauropods are represented by medium to large sized and narrow and wide-gauge groups, respectively. The latter correspond with earlier discoveries of titanosauriform skeletons in the same unit. Previous records of ornithischian tracks cannot be positively confirmed. Purported occurrences are re-evaluated here, the trackways and imprints, except of a single possible specimen, re-assigned to theropods. Palecologically the Tuchengzi ichnofauna is characteristic of semi-arid fluvio-lacustrine inland basins with Upper Jurassic-Lower Cretaceous deposits in northern China that all show assemblages with abundant theropod and sauropod tracks and minor components of ornithopod, pterosaur and bird tracks.

  2. Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine oxide particles in the coastal marine boundary layer

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2012-03-01

    Full Text Available Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. There has been some debate over the chemical identity of these particles. Hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5 · H2O. In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH. On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass, but subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only ~6 %, which is remarkably small for a highly soluble material. We suggest that the small growth factor of aqueous iodic acid solution droplets is consistent with the small aerosol growth factors observed in field experiments.

  3. The Role of the Regulated Sector in the UK Anti-Money Laundering Framework: Pushing the Boundaries of the Private Police

    Directory of Open Access Journals (Sweden)

    Mo Egan

    2010-06-01

    Full Text Available This article argues that the conceptualisation of private police in current academic literature requires expansion to accommodate the role of the regulated sector in the Anti- Money Laundering (AML framework. Firstly, it evaluates the literature on ‘private police’ and argues that its current parameters are too narrow to accommodate the ‘policing’ role of the regulated sector. Secondly, it lays out the legislative framework that has developed to deal with the problem of money laundering. Thirdly, it contextualises the role of the regulated sector, examining the domestic inter-agency policing relationships within the suspicious activity regime as operationalised in Scotland. Finally, it takes a closer look at how the courts have interpreted the ‘failure to report offence’ under s330 of the Proceeds of Crime Act (POCA 2002 and its consequential effect on the engagement of the regulated sector with the SARs regime.

  4. Regulation of Stem Cell Proliferation and Cell Fate Specification by Wingless/Wnt Signaling Gradients Enriched at Adult Intestinal Compartment Boundaries.

    OpenAIRE

    Ai Tian; Hassina Benchabane; Zhenghan Wang; Yashi Ahmed

    2016-01-01

    Intestinal stem cell (ISC) self-renewal and proliferation are directed by Wnt/β-catenin signaling in mammals, whereas aberrant Wnt pathway activation in ISCs triggers the development of human colorectal carcinoma. Herein, we have utilized the Drosophila midgut, a powerful model for ISC regulation, to elucidate the mechanisms by which Wingless (Wg)/Wnt regulates intestinal homeostasis and development. We provide evidence that the Wg signaling pathway, activation of which peaks at each of the m...

  5. Type III methyltransferase M.NgoAX from Neisseria gonorrhoeae FA1090 regulates biofilm formation and human cell invasion

    Directory of Open Access Journals (Sweden)

    Agnieszka eKwiatek

    2015-12-01

    , but more easily penetrate inside the host cells. All these data suggest that the NgoAX methyltransferase, may be implicated in N. gonorrhoeae pathogenicity, involving regulation of biofilm formation, adhesion to host cells and epithelial cell invasion.

  6. Sex-Dependent Up-Regulation of Two Splicing Factors, Psf and Srp20, during Hippocampal Memory Formation

    Science.gov (United States)

    Antunes-Martins, Ana; Mizuno, Keiko; Irvine, Elaine E.; Lepicard, Eve M.; Giese, K. Peter

    2007-01-01

    Gene transcription is required for long-term memory (LTM) formation. LTM formation is impaired in a male-specific manner in mice lacking either of the two Ca[superscript 2+] / calmodulin-dependent kinase kinase ("Camkk") genes. Since altered transcription was suggested to cause these impairments in LTM formation, we used microarrays to screen for…

  7. Boundary layer regulation in the southeast Atlantic cloud microphysics during the biomass burning season as seen by the A-train satellite constellation

    Science.gov (United States)

    Painemal, David; Kato, Seiji; Minnis, Patrick

    2014-10-01

    Solar radiation absorption by biomass burning aerosols has a strong warming effect over the southeast Atlantic. Interactions between the overlying smoke aerosols and low-level cloud microphysics and the subsequent albedo perturbation are, however, generally ignored in biomass burning radiative assessments. In this study, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are combined with Aqua satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Microwave Scanning Radiometer-EOS (AMSR-E), and Clouds and the Earth's Radiant Energy System (CERES) to assess the effect of variations in the boundary layer height and the separation distance between the cloud and aerosol layers on the cloud microphysics. The merged data analyzed at a daily temporal resolution suggest that overlying smoke aerosols modify cloud properties by decreasing cloud droplet size despite an increase in the cloud liquid water as boundary layer deepens, north of 5°S. These changes are controlled by the proximity of the aerosol layer to the cloud top rather than increases in the column aerosol load. The correlations are unlikely driven by meteorological factors, as three predictors of cloud variability, lower tropospheric stability, surface winds, and mixing ratio suggest that cloud effective radius, cloud top height, and liquid water path should correlate positively. Because cloud effective radius anticorrelates with cloud liquid water over the region with large microphysical changes—north of 5°S—the overall radiative consequence at the top of the atmosphere is a strong albedo susceptibility, equivalent to a 3% albedo increase due to a 10% decrease in cloud effective radius. This albedo enhancement partially offsets the aerosol solar absorption. Our analysis emphasizes the importance of accounting for the indirect effect of smoke aerosols in the cloud microphysics when estimating the radiative impact of the biomass burning at the

  8. Genome-wide mutagenesis of Xanthomonas axonopodis pv. citri reveals novel genetic determinants and regulation mechanisms of biofilm formation.

    Directory of Open Access Journals (Sweden)

    Jinyun Li

    Full Text Available Xanthomonas axonopodis pv. citri (Xac causes citrus canker disease, a major threat to citrus production worldwide. Accumulating evidence suggests that the formation of biofilms on citrus leaves plays an important role in the epiphytic survival of this pathogen prior to the development of canker disease. However, the process of Xac biofilm formation is poorly understood. Here, we report a genome-scale study of Xac biofilm formation in which we identified 92 genes, including 33 novel genes involved in biofilm formation and 7 previously characterized genes, colR, fhaB, fliC, galU, gumD, wxacO, and rbfC, known to be important for Xac biofilm formation. In addition, 52 other genes with defined or putative functions in biofilm formation were identified, even though they had not previously reported been to be associated with biofilm formation. The 92 genes were isolated from 292 biofilm-defective mutants following a screen of a transposon insertion library containing 22,000 Xac strain 306 mutants. Further analyses indicated that 16 of the novel genes are involved in the production of extracellular polysaccharide (EPS and/or lipopolysaccharide (LPS, 7 genes are involved in signaling and regulatory pathways, and 5 genes have unknown roles in biofilm formation. Furthermore, two novel genes, XAC0482, encoding a haloacid dehalogenase-like phosphatase, and XAC0494 (designated as rbfS, encoding a two-component sensor protein, were confirmed to be biofilm-related genes through complementation assays. Our data demonstrate that the formation of mature biofilm requires EPS, LPS, both flagellum-dependent and flagellum-independent cell motility, secreted proteins and extracellular DNA. Additionally, multiple signaling pathways are involved in Xac biofilm formation. This work is the first report on a genome-wide scale of the genetic processes of biofilm formation in plant pathogenic bacteria. The report provides significant new information about the genetic

  9. Up-regulation of Ras/Raf/ERK1/2 signaling in the spinal cord impairs neural cell migration, neurogenesis, synapse formation, and dendritic spine development

    Institute of Scientific and Technical Information of China (English)

    CAO Fu-jiang; ZHANG Xu; LIU Tao; LI Xia-wen; Mazar Malik; FENG Shi-qing

    2013-01-01

    Background The Ras/Raf/ERK1/2 signaling pathway controls many cellular responses such as cell proliferation,migration,differentiation,and death.In the nervous system,emerging evidence also points to a death-promoting role for ERK1/2 in both in vitro and in vivo models of neuronal death.To further investigate how Ras/Raf/ERK1/2 up-regulation may lead to the development of spinal cord injury,we developed a cellular model of Raf/ERK up-regulation by overexpressing c-Raf in cultured spinal cord neurons (SCNs) and dorsal root ganglions (DRGs).Methods DRGs and SCNs were prepared from C57BL/6J mouse pups.DRGs or SCNs were infected with Ad-Raf-1 or Ad-Null adenovirus alone.Cell adhesion assay and cell migration assay were investigated,Dil labeling was employed to examine the effect of the up-regulation of Ras/Raf/ERK1/2 signaling on the dendritic formation of spinal neurons.We used the TO-PRO-3 staining to examine the apoptotic effect of c-Raf on DRGs or SCNs.The effect on the synapse formation of neurons was measured by using immunofluorescence.Results We found that Raf/ERK up-regulation stimulates the migration of both SCNs and DRGs,and impairs the formation of excitatory synapses in SCNs.In addition,we found that Raf/ERK up-regulation inhibits the development of mature dendritic spines in SCNs.Investigating the possible mechanisms through which Raf/ERK up-regulation affects the excitatory synapse formation and dendritic spine development,we discovered that Raf/ERK up-regulation suppresses the development and maturation of SCNs.Conclusion The up-regulation of the Raf/ERK signaling pathway may contribute to the pathogenesis of spinal cord injury through both its impairment of the SCN development and causing neural circuit imbalances.

  10. SIMULATIVE INVESTIGATION OF GRAIN BOUNDARIES IN NiAl ALLOY

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Using embedded atom potentials and molecular static relaxation method or Monte Carlo relaxation method, the grain boundary atomic structures of a series of [100], [110] and [111] symmetric tilt grain boundaries in NiAl with different geometrical indexes and compositions were studied. The grain boundary energies, grain boundary cohesive energies and point defects formation energies at the grain boundary were calculated. The results show that the grain boundaries of NiAl alloy have a periodic unit structure. Grain boundary energies of Al rich grain boundary is very high, but the cohesive energies are lower than those of others. The interaction of point defects and grain boundaries shows that grain boundaries incline to absorb point defects to decrease their orders and to relax the distortions caused by point defects. The boundary atomic structures relaxed by Monte Carlo method show that the disorder of them, grain boundary energies and cohesive energies increase with increasing temperature.

  11. Live imaging of Drosophila gonad formation reveals roles for Six4 in regulating germline and somatic cell migration

    Directory of Open Access Journals (Sweden)

    Jarman Andrew P

    2007-05-01

    Full Text Available Abstract Background Movement of cells, either as amoeboid individuals or in organised groups, is a key feature of organ formation. Both modes of migration occur during Drosophila embryonic gonad development, which therefore provides a paradigm for understanding the contribution of these processes to organ morphogenesis. Gonads of Drosophila are formed from three distinct cell types: primordial germ cells (PGCs, somatic gonadal precursors (SGPs, and in males, male-specific somatic gonadal precursors (msSGPs. These originate in distinct locations and migrate to associate in two intermingled clusters which then compact to form the spherical primitive gonads. PGC movements are well studied, but much less is known of the migratory events and other interactions undergone by their somatic partners. These appear to move in organised groups like, for example, lateral line cells in zebra fish or Drosophila ovarian border cells. Results We have used time-lapse fluorescence imaging to characterise gonadal cell behaviour in wild type and mutant embryos. We show that the homeodomain transcription factor Six4 is required for the migration of the PGCs and the msSGPs towards the SGPs. We have identified a likely cause of this in the case of PGCs as we have found that Six4 is required for expression of Hmgcr which codes for HMGCoA reductase and is necessary for attraction of PGCs by SGPs. Six4 affects msSGP migration by a different pathway as these move normally in Hmgcr mutant embryos. Additionally, embryos lacking fully functional Six4 show a novel phenotype in which the SGPs, which originate in distinct clusters, fail to coalesce to form unified gonads. Conclusion Our work establishes the Drosophila gonad as a model system for the analysis of coordinated cell migrations and morphogenesis using live imaging and demonstrates that Six4 is a key regulator of somatic cell function during gonadogenesis. Our data suggest that the initial association of SGP clusters

  12. Galaxy Formation with Self-consistently Modeled Stars and Massive Black Holes. I: Feedback-regulated Star Formation and Black Hole Growth

    CERN Document Server

    Kim, Ji-hoon; Abel, Tom

    2011-01-01

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto a MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full 3D adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2e11 Msun galactic halo and its 1e5 Msun embedded MBH at redshift 3 in a cosmological LCDM simulation. The MBH feedback heats the surrounding ISM up to 1e6 K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. T...

  13. Technology for Boundaries

    DEFF Research Database (Denmark)

    Bødker, Susanne; Kristensen, Jannie Friis; Nielsen, Christina;

    2003-01-01

    This paper presents a study of an organisation, which is undergoing a process transforming organisational and technological boundaries. In particular, we shall look at three kinds of boundaries: the work to maintain and change the boundary between the organisation and its customers; boundaries.......After analysing the history and the current boundary work, the paper will propose new technological support for boundary work. In particular the paper will suggest means of supporting boundaries when these are productive and for changing boundaries when this seems more appropriate. In total, flexible technologies...... seem a core issue when dealing with technology for boundaries....

  14. Lamellar eutectic growth with anisotropic interphase boundaries

    OpenAIRE

    Akamatsu, Silvère; Bottin-Rousseau, Sabine; Faivre, G.; Ghosh, S.; Plapp, M.

    2015-01-01

    We present a numerical study of the effect of a free-energy anisotropy of the solid- solid interphase boundaries on the formation of tilted lamellar microstructures during directional solidification of nonfaceted binary eutectic alloys. We used two different methods - phase-field (PF) and dynamic boundary-integral (BI) - to simulate the growth of periodic eutectic patterns in two dimensions. For a given Wulff plot of the interphase boundary, which characterizes a eutectic grain with a given r...

  15. The two-component signal transduction system ArlRS regulates Staphylococcus epidermidis biofilm formation in an ica-dependent manner.

    Directory of Open Access Journals (Sweden)

    Yang Wu

    Full Text Available Due to its ability to form biofilms on medical devices, Staphylococcus epidermidis has emerged as a major pathogen of nosocomial infections. In this study, we investigated the role of the two-component signal transduction system ArlRS in regulating S. epidermidis biofilm formation. An ArlRS-deficient mutant, WW06, was constructed using S. epidermidis strain 1457 as a parental strain. Although the growth curve of WW06 was similar to that of SE1457, the mutant strain was unable to form biofilms in vitro. In a rabbit subcutaneous infection model, sterile disks made of polymeric materials were implanted subcutaneously followed with inoculation of WW06 or SE1457. The viable bacteria cells of WW06 recovered from biofilms on the embedded disks were much lower than that of SE1457. Complementation of arlRS genes expression from plasmid in WW06 restored biofilm-forming phenotype both in vivo and in vitro. WW06 maintained the ability to undergo initial attachment. Transcription levels of several genes involved in biofilm formation, including icaADBC, sigB, and sarA, were decreased in WW06, compared to SE1457; and icaR expression was increased in WW06, detected by real-time reverse-transcription PCR. The biofilm-forming phenotype was restored by overexpressing icaADBC in WW06 but not by overexpressing sigB, indicating that ArlRS regulates biofilm formation through the regulation of icaADBC. Gel shift assay showed that ArlR can bind to the promoter region of the ica operon. In conclusion, ArlRS regulates S. epidermidis biofilm formation in an ica-dependent manner, distinct from its role in S. aureus.

  16. [Nitrogen oxide is involved in the regulation of the Fe-S cluster assembly in proteins and the formation of biofilms by Escherichia coli cells].

    Science.gov (United States)

    Vasil'eva, S V; Streltsova, D A; Starostina, I A; Sanina, N A

    2013-01-01

    The functions of nitrogen oxide (NO) in the regulation of the reversible processes of Fe-S cluster assembly in proteins and the formation of Escherichia coli biofilms have been investigated. S-nitrosoglutathione (GSNO) and crystalline nitrosyl complexes of iron with sulfur-containing aliphatic ligands cisaconite (CisA) and penaconite have been used as NO donors for the first time. Wild-type E. coli cells of the strain MC4100, mutants deltaiscA and deltasufA, and the double paralog mutant deltaiscA/sufA with deletions in the alternative pathways of Fe2+ supply for cluster assembly (all derived from the above-named strain) were used in this study. Plankton growth of bacterial cultures, the mass of mature biofilms, and the expression of the SoxRS[2Fe-2S] regulon have been investigated and shown to depend on strain genotype, the process of Fe-S cluster assembly in iron-sulfur proteins, NO donor structure, and the presence of Fe2+ chelator ferene in the incubation medium. The antibiotic ciprofloxacine (CF) was used as an inhibitor of E. coli biofilm formation in the positive control. NO donors regulating Fe-S cluster assembly in E. coli have been shown to control plankton growth of the cultures and the process of mature biofilm formation; toxic doses of NO caused a dramatic (3- to 4-fold) stimulation of cell entry into biofilms as a response to nitrosative stress; NO donors CisA and GSNO in physiological concentrations suppressed the formation of mature biofilms, and the activity of these compounds was comparable to that of CE Regulation of both Fe-S cluster assembly in iron-sulfur proteins and biofilm formation by NO is indicative of the connection between these processes in E. coli.

  17. Chromoproteinoids and their ability to form boundary

    International Nuclear Information System (INIS)

    Model systems for boundary structures and cellular systems, particularly when they are a result of natural simulation experiments, are always valuable for the study of the ''Origins of Life''. Lyophilization of chromoproteinoids - peptide like molecules containing prosthetic groups - leads to the formation of boundary structures

  18. Formation and dimerization of the phosphodiesterase active site of the Pseudomonas aeruginosa MorA, a bi-functional c-di-GMP regulator.

    Science.gov (United States)

    Phippen, Curtis William; Mikolajek, Halina; Schlaefli, Henry George; Keevil, Charles William; Webb, Jeremy Stephen; Tews, Ivo

    2014-12-20

    Diguanylate cyclases (DGC) and phosphodiesterases (PDE), respectively synthesise and hydrolyse the secondary messenger cyclic dimeric GMP (c-di-GMP), and both activities are often found in a single protein. Intracellular c-di-GMP levels in turn regulate bacterial motility, virulence and biofilm formation. We report the first structure of a tandem DGC-PDE fragment, in which the catalytic domains are shown to be active. Two phosphodiesterase states are distinguished by active site formation. The structures, in the presence or absence of c-di-GMP, suggest that dimerisation and binding pocket formation are linked, with dimerisation being required for catalytic activity. An understanding of PDE activation is important, as biofilm dispersal via c-di-GMP hydrolysis has therapeutic effects on chronic infections.

  19. Lrp4 regulates initiation of ureteric budding and is crucial for kidney formation--a mouse model for Cenani-Lenz syndrome.

    Directory of Open Access Journals (Sweden)

    Courtney M Karner

    Full Text Available BACKGROUND: Development of the kidney is initiated when the ureteric bud (UB branches from the Wolffian duct and invades the overlying metanephric mesenchyme (MM triggering the mesenchymal/epithelial interactions that are the basis of organ formation. Multiple signaling pathways must be integrated to ensure proper timing and location of the ureteric bud formation. METHODS AND PRINCIPAL FINDINGS: We have used gene targeting to create an Lrp4 null mouse line. The mutation results in early embryonic lethality with a subpenetrant phenotype of kidney agenesis. Ureteric budding is delayed with a failure to stimulate the metanephric mesenchyme in a timely manner, resulting in failure of cellular differentiation and resulting absence of kidney formation in the mouse as well as comparable malformations in humans with Cenani-Lenz syndrome. CONCLUSION: Lrp4 is a multi-functional receptor implicated in the regulation of several molecular pathways, including Wnt and Bmp signaling. Lrp4(-/- mice show a delay in ureteric bud formation that results in unilateral or bilateral kidney agenesis. These data indicate that Lrp4 is a critical regulator of UB branching and lack of Lrp4 results in congenital kidney malformations in humans and mice.

  20. Atlantic NAD 83 Continental Shelf Boundary (CSB)

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Continental Shelf Boundary (CSB) lines in ESRI shapefile format for the BOEM Atlantic Region. The CSB defines the seaward limit of federally...

  1. Continental Shelf Boundary - Alaska NAD83

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Continental Shelf Boundaries (CSB) lines in ESRI shapefile format for the BOEM Alaska Region. The CSB defines the seaward limit of federally...

  2. Nonneuronal cells regulate synapse formation in the vestibular sensory epithelium via erbB-dependent BDNF expression

    OpenAIRE

    Gómez-Casati, Maria E; MURTIE, JOSHUA C.; Rio, Carlos; Stankovic, Konstantina; Liberman, M. Charles; Corfas, Gabriel

    2010-01-01

    Recent studies indicate that molecules released by glia can induce synapse formation. However, what induces glia to produce such signals, their identity, and their in vivo relevance remain poorly understood. Here we demonstrate that supporting cells of the vestibular organ—cells that have many characteristics of glia—promote synapse formation only when induced by neuron-derived signals. Furthermore, we identify BDNF as the synaptogenic signal produced by these nonneuronal cells. Mice in which...

  3. Outer Continental Shelf Submerged Lands Act Boundary - Atlantic Region NAD83

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains the Submerged Lands Act (SLA) boundary line (also known as State Seaward Boundary (SSB), or Fed State Boundary) in ESRI shapefile formats for...

  4. Outer Continental Shelf Submerged Lands Act Boundary - Alaska Region NAD83

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains the Submerged Lands Act (SLA) boundary (also known as State Seaward Boundary (SSB), or Fed State Boundary) in ESRI shapefile format for the...

  5. Outer Continental Shelf Submerged Lands Act Boundary - Gulf of Mexico Region NAD27

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains the Submerged Lands Act (SLA) boundary line (also known as State Seaward Boundary (SSB), or Fed State Boundary)in ESRI shapefile formats for...

  6. THE FORMATION OF THE STRATEGY OF STATE REGULATION OF THE ESTABLISHMENT AND OPERATION OF INDUSTRIAL AND LOGISTICS SYSTEMS

    OpenAIRE

    Dykan, V.

    2014-01-01

    It is proved that the starting point in the development strategy of state regulation should be scientifically justified and described in detail the concept. It is only on the basis considering factors external and internal environment it is possible to determine the main objective of the strategy and to develop an effective strategy of state regulation. Given the theoretical foundations of industrial and logistics integration of industrial enterprises and their importance in ensuring the comp...

  7. A universal, turbulence-regulated star formation law: from Milky Way clouds to high-redshift disk and starburst galaxies

    CERN Document Server

    Salim, Diane M; Kewley, Lisa J

    2015-01-01

    Whilst the star formation rate (SFR) of molecular clouds and galaxies is key in understanding galaxy evolution, the physical processes which determine the SFR remain unclear. This uncertainty about the underlying physics has resulted in various different star formation laws, all having substantial intrinsic scatter. Extending upon previous works that define the column density of star formation (Sigma_SFR) by the gas column density (Sigma_gas), we develop a new universal star formation (SF) law based on the multi-freefall prescription of gas. This new SF law relies predominantly on the probability density function (PDF) and on the sonic Mach number of the turbulence in the star-forming clouds. By doing so we derive a relation where the star formation rate (SFR) correlates with the molecular gas mass per multi-freefall time, whereas previous models had used the average, single-freefall time. We define a new quantity called maximum (multi-freefall) gas consumption rate (MGCR) and show that the actual SFR is only...

  8. Neocarzinostatin-induced Rad51 nuclear focus formation is cell cycle regulated and aberrant in AT cells

    International Nuclear Information System (INIS)

    DNA double-stranded breaks are the most detrimental form of DNA damage and, if not repaired properly, may lead to an accumulation of chromosomal aberrations and eventually tumorigenesis. Proteins of the Rad51/Rad52 epitasis group are crucial for the recombinational repair of DNA double-stranded breaks, whereas the Rad50/NBS1/Mre11 nuclease complex is involved in both the recombinational and the end-joining repair of DNA double-stranded breaks. Herein, we demonstrate that the chemotherapeutic enediyne antibiotic neocarzinostatin induced Rad51, but not NBS1, nuclear focus formation in a cell- cycle-dependent manner. Furthermore, neocarzinostatin-induced Rad51 foci formation revealed a slower kinetic change in AT cells, but not in wild-type or NBS cells. In summary, our results suggest that neocarzinostatin induces Rad51 focus formation through an ATM- and cell-cycle-dependent, but NBS1-independent, pathway

  9. Putative zeatin O-glucosyltransferase OscZOG1 regulates root and shoot development and formation of agronomic traits in rice

    Institute of Scientific and Technical Information of China (English)

    Fang-Qing Guo

    2016-01-01

    As a ubiquitous reaction, glucosylation controls the bioactivity of cytokinins in plant growth and development. Here we show that genetic manipulation of zeatin-O-glucosylation regulates the formation of important agronomic traits in rice by manipulating the expression of OscZOG1 gene, encoding a putative zeatin O-glucosyltransferase. We found that OscZOG1 was preferentially expressed in shoot and root meristematic tissues and nascent organs. The growth of lateral roots was stimulated in the overexpression lines, but inhibited in RNA interference lines. In shoots, knockdown of OscZOG1 expression by RNA interference significantly im-proved tillering, panicle branching, grain number per panicle and seed size, which are important agronomic traits for grain yield. In contrast, constitutive expression of OscZOG1 leads to negative effects on the formation of the grain-yielding traits with a marked increase in the accumulation levels of cis-zeatin O-glucoside (cZOG) in the transgenic rice plants. In this study, our findings demonstrate the feasibility of improving the critical yield-determinant agronomic traits, including tiller number, panicle branches, total grain number per panicle and grain weight by downregulating the expression level of OscZOG1. Our results suggest that modulating the levels of cytokinin glucosylation can function as a fine-tuning switch in regulating the formation of agronomic traits in rice.

  10. Identification of flgZ as a flagellar gene encoding a PilZ domain protein that regulates swimming motility and biofilm formation in Pseudomonas.

    Directory of Open Access Journals (Sweden)

    Francisco Martínez-Granero

    Full Text Available Diguanylate cyclase and phosphodiesterase enzymatic activities control c-di-GMP levels modulating planktonic versus sessile lifestyle behavior in bacteria. The PilZ domain is described as a sensor of c-di-GMP intracellular levels and the proteins containing a PilZ domain represent the best studied class of c-di-GMP receptors forming part of the c-di-GMP signaling cascade. In P. fluorescens F113 we have found two diguanylate cyclases (WspR, SadC and one phosphodiesterase (BifA implicated in regulation of swimming motility and biofilm formation. Here we identify a flgZ gene located in a flagellar operon encoding a protein that contains a PilZ domain. Moreover, we show that FlgZ subcellular localization depends on the c-di-GMP intracellular levels. The overexpression analysis of flgZ in P. fluorescens F113 and P. putida KT2440 backgrounds reveal a participation of FlgZ in Pseudomonas swimming motility regulation. Besides, the epistasis of flgZ over wspR and bifA clearly shows that c-di-GMP intracellular levels produced by the enzymatic activity of the diguanylate cyclase WspR and the phosphodiesterase BifA regulates biofilm formation through FlgZ.

  11. Identification of flgZ as a flagellar gene encoding a PilZ domain protein that regulates swimming motility and biofilm formation in Pseudomonas.

    Science.gov (United States)

    Martínez-Granero, Francisco; Navazo, Ana; Barahona, Emma; Redondo-Nieto, Miguel; González de Heredia, Elena; Baena, Irene; Martín-Martín, Irene; Rivilla, Rafael; Martín, Marta

    2014-01-01

    Diguanylate cyclase and phosphodiesterase enzymatic activities control c-di-GMP levels modulating planktonic versus sessile lifestyle behavior in bacteria. The PilZ domain is described as a sensor of c-di-GMP intracellular levels and the proteins containing a PilZ domain represent the best studied class of c-di-GMP receptors forming part of the c-di-GMP signaling cascade. In P. fluorescens F113 we have found two diguanylate cyclases (WspR, SadC) and one phosphodiesterase (BifA) implicated in regulation of swimming motility and biofilm formation. Here we identify a flgZ gene located in a flagellar operon encoding a protein that contains a PilZ domain. Moreover, we show that FlgZ subcellular localization depends on the c-di-GMP intracellular levels. The overexpression analysis of flgZ in P. fluorescens F113 and P. putida KT2440 backgrounds reveal a participation of FlgZ in Pseudomonas swimming motility regulation. Besides, the epistasis of flgZ over wspR and bifA clearly shows that c-di-GMP intracellular levels produced by the enzymatic activity of the diguanylate cyclase WspR and the phosphodiesterase BifA regulates biofilm formation through FlgZ.

  12. Identification of a chemical inhibitor for nuclear speckle formation: Implications for the function of nuclear speckles in regulation of alternative pre-mRNA splicing

    International Nuclear Information System (INIS)

    Highlights: • We identified tubercidin as a compound inducing aberrant formation of the speckles. • Tubercidin causes delocalization of poly (A)+RNAs from nuclear speckles. • Tubercidin induces dispersion of splicing factors from nuclear speckles. • Tubercidin affects alternative pre-mRNA splicing. • Nuclear speckles play a role in regulation of alternative pre-mRNA splicing. - Abstract: Nuclear speckles are subnuclear structures enriched with RNA processing factors and poly (A)+ RNAs comprising mRNAs and poly (A)+ non-coding RNAs (ncRNAs). Nuclear speckles are thought to be involved in post-transcriptional regulation of gene expression, such as pre-mRNA splicing. By screening 3585 culture extracts of actinomycetes with in situ hybridization using an oligo dT probe, we identified tubercidin, an analogue of adenosine, as an inhibitor of speckle formation, which induces the delocalization of poly (A)+ RNA and dispersion of splicing factor SRSF1/SF2 from nuclear speckles in HeLa cells. Treatment with tubercidin also decreased steady-state MALAT1 long ncRNA, thought to be involved in the retention of SRSF1/SF2 in nuclear speckles. In addition, we found that tubercidin treatment promoted exon skipping in the alternative splicing of Clk1 pre-mRNA. These results suggest that nuclear speckles play a role in modulating the concentration of splicing factors in the nucleoplasm to regulate alternative pre-mRNA splicing

  13. Identification of a chemical inhibitor for nuclear speckle formation: Implications for the function of nuclear speckles in regulation of alternative pre-mRNA splicing

    Energy Technology Data Exchange (ETDEWEB)

    Kurogi, Yutaro; Matsuo, Yota; Mihara, Yuki; Yagi, Hiroaki; Shigaki-Miyamoto, Kaya; Toyota, Syukichi; Azuma, Yuko [Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555 (Japan); Igarashi, Masayuki [Laboratory of Disease Biology, Institute of Microbial Chemistry, Shinagawa-ku, Tokyo 141-0021 (Japan); Tani, Tokio, E-mail: ttani@sci.kumamoto-u.ac.jp [Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555 (Japan)

    2014-03-28

    Highlights: • We identified tubercidin as a compound inducing aberrant formation of the speckles. • Tubercidin causes delocalization of poly (A){sup +}RNAs from nuclear speckles. • Tubercidin induces dispersion of splicing factors from nuclear speckles. • Tubercidin affects alternative pre-mRNA splicing. • Nuclear speckles play a role in regulation of alternative pre-mRNA splicing. - Abstract: Nuclear speckles are subnuclear structures enriched with RNA processing factors and poly (A){sup +} RNAs comprising mRNAs and poly (A){sup +} non-coding RNAs (ncRNAs). Nuclear speckles are thought to be involved in post-transcriptional regulation of gene expression, such as pre-mRNA splicing. By screening 3585 culture extracts of actinomycetes with in situ hybridization using an oligo dT probe, we identified tubercidin, an analogue of adenosine, as an inhibitor of speckle formation, which induces the delocalization of poly (A){sup +} RNA and dispersion of splicing factor SRSF1/SF2 from nuclear speckles in HeLa cells. Treatment with tubercidin also decreased steady-state MALAT1 long ncRNA, thought to be involved in the retention of SRSF1/SF2 in nuclear speckles. In addition, we found that tubercidin treatment promoted exon skipping in the alternative splicing of Clk1 pre-mRNA. These results suggest that nuclear speckles play a role in modulating the concentration of splicing factors in the nucleoplasm to regulate alternative pre-mRNA splicing.

  14. Adenosine contributes to blood flow regulation in the exercising human leg by increasing prostaglandin and nitric oxide formation

    DEFF Research Database (Denmark)

    Mortensen, Stefan; Nyberg, Michael; Thaning, Pia;

    2009-01-01

    Adenosine can induce vasodilation in skeletal muscle, but to what extent adenosine exerts its effect via formation of other vasodilators and whether there is redundancy between adenosine and other vasodilators remain unclear. We tested the hypothesis that adenosine, prostaglandins, and NO act in...

  15. Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. I. Star Formation Rate and Efficiency

    Science.gov (United States)

    Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

    2016-10-01

    Radiation feedback from stellar clusters is expected to play a key role in setting the rate and efficiency of star formation in giant molecular clouds. To investigate how radiation forces influence realistic turbulent systems, we have conducted a series of numerical simulations employing the Hyperion radiation hydrodynamics solver, considering the regime that is optically thick to ultraviolet and optically thin to infrared radiation. Our model clouds cover initial surface densities between Σ cl,0∼ 10--300 M⊙ pc-2, with varying initial turbulence. We follow them through turbulent, self-gravitating collapse, star cluster formation, and cloud dispersal by stellar radiation. All our models display a log-normal distribution of gas surface density Σ for an initial virial parameter αvir,0=2, the log-normal standard deviation is σln Σ =1-1.5 and the star formation rate coefficient ɛff,ρ=0.3-0.5, both of which are sensitive to turbulence but not radiation feedback. The net star formation efficiency (SFE) ɛfinal increases with Σcl,0 and decreases with α vir,0. We interpret these results via a simple conceptual framework, whereby steady star formation increases the radiation force, such that local gas patches at successively higher Σ become unbound. Based on this formalism (with fixed σln Σ), we provide an analytic upper bound on ɛfinal, which is in good agreement with our numerical results. The final SFE depends on the distribution of Eddington ratios in the cloud and is strongly increased by the turbulent compression of gas.

  16. The K/T-boundary carbonate breccia succession at the Cantarell Field, Campeche Bay area: a representative example of the influence of the Chicxulub meteorite-impact event on the formation of extraordinary petroleum reservoirs

    Science.gov (United States)

    Murillo-Muñeton, G.; Grajales-Nishimura, J. M.; Velasquillo-Martínez, L. G.; García-Hernández, J.

    2013-05-01

    Over the last decade, intense petroleum exploration and exploitation activities have been conducted in the Campeche Bay area. Detailed stratigraphic studies in this region based on seismic, well logs, and core data have allowed the documentation of numerous deep-water carbonate breccia deposits throughout the Cretaceous stratigraphic column. However, the uppermost carbonate breccia succession is very distinctive in terms of its sedimentological properties compared to the underlying and older calcareous breccia layers. The unique characteristics of this deposit include: its unusual thickness, stratigraphic position, distribution, and content of impact-metamorphic constituents. At the Cantarell field, this carbonate breccia sedimentary package is a representative example of how the Chuxulub meteorite-impact event influenced the formation of a remarkable carbonate reservoir. This deposit was the most important oil-producing stratigraphic horizon for long time in that field. Nevertheless, this reservoir is still important not only in that field but also in other fields in offshore Campeche. The K/T boundary carbonate breccia succession is a typical fining-upward deposit made up, from base to top, of three units. The 50 to 300-m thick, basal Unit 1 consists of a coarse-grained carbonate breccia. Unit 2 is a 10 to 20 m-thick, fine-grained carbonate breccia. The 25 to 30 m-thick, uppermost Unit 3 is a greenish interval of friable sand, silt and clay-sized constituents with abundant ejecta material. In some wells, a 10 to 20 m-thick, non-oil producing fine-grained calcareous breccia occurs interbedded within Unit 3. The K/T boundary carbonate sedimentary package is underlain and overlain by deep-water shaly calcareous facies of Upper Maastrichtian and Lower Paleocene age, respectively. Studies of cronostratigraphic-equivalent outcrop analogs of this K/T boundary carbonate reservoir carried out by the authors in the Sierra de Chiapas (El Guayal, Tabasco and Bochil, Chiapas

  17. The small GTPase Rab5 homologue Ypt5 regulates cell morphology, sexual development, ion-stress response and vacuolar formation in fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Tsukamoto, Yuta; Katayama, Chisako [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho Nada, Kobe 657-8501 (Japan); Shinohara, Miki; Shinohara, Akira [Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Maekawa, Shohei [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho Nada, Kobe 657-8501 (Japan); Miyamoto, Masaaki, E-mail: miya@kobe-u.ac.jp [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho Nada, Kobe 657-8501 (Japan); Center for Supports to Research and Education Activities, Kobe University, 1-1 Rokkodai-cho Nada, Kobe 657-8501 (Japan)

    2013-11-29

    Highlights: •Multiple functions of Rab5 GTPase in fission yeast were found. •Roles of Rab5 in fission yeast were discussed. •Relation between Rab5 and actin cytoskeleton were discussed. -- Abstract: Inner-membrane transport is critical to cell function. Rab family GTPases play an important role in vesicle transport. In mammalian cells, Rab5 is reported to be involved in the regulation of endosome formation, phagocytosis and chromosome alignment. Here, we examined the role of the fission yeast Rab5 homologue Ypt5 using a point mutant allele. Mutant cells displayed abnormal cell morphology, mating, sporulation, endocytosis, vacuole fusion and responses to ion stress. Our data strongly suggest that fission yeast Rab5 is involved in the regulation of various types of cellular functions.

  18. MicroRNA-17-mediated down-regulation of apoptotic protease activating factor 1 attenuates apoptosome formation and subsequent apoptosis of cardiomyocytes.

    Science.gov (United States)

    Song, Seungjun; Seo, Hyang-Hee; Lee, Se-Yeon; Lee, Chang Yeon; Lee, Jiyun; Yoo, Kyung-Jong; Yoon, Cheesoon; Choi, Eunhyun; Hwang, Ki-Chul; Lee, Seahyoung

    2015-09-18

    Heart diseases such as myocardial infarction (MI) can damage individual cardiomyocytes, leading to the activation of cell death programs. The most scrutinized type of cell death in the heart is apoptosis, and one of the key events during the propagation of apoptotic signaling is the formation of apoptosomes, which relay apoptotic signals by activating caspase-9. As one of the major components of apoptosomes, apoptotic protease activating factor 1 (Apaf-1) facilitates the formation of apoptosomes containing cytochrome c (Cyto-c) and deoxyadenosine triphosphate (dATP). Thus, it may be possible to suppress the activation of the apoptotic program by down-regulating the expression of Apaf-1 using miRNAs. To validate this hypothesis, we selected a number of candidate miRNAs that were expected to target Apaf-1 based on miRNA target prediction databases. Among these candidate miRNAs, we empirically identified miR-17 as a novel Apaf-1-targeting miRNA. The delivery of exogenous miR-17 suppressed Apaf-1 expression and consequently attenuated formation of the apoptosome complex containing caspase-9, as demonstrated by co-immunoprecipitation and immunocytochemistry. Furthermore, miR-17 suppressed the cleavage of procaspase-9 and the subsequent activation of caspase-3, which is downstream of activated caspase-9. Cell viability tests also indicated that miR-17 pretreatment significantly prevented the norepinephrine-induced apoptosis of cardiomyocytes, suggesting that down-regulation of apoptosome formation may be an effective strategy to prevent cellular apoptosis. These results demonstrate the potential of miR-17 as an effective anti-apoptotic agent. PMID:26265044

  19. Self-Regulated Fueling of Galaxy Centers: Evidence for Star-Formation Feedback in IC342's Nucleus

    CERN Document Server

    Schinnerer, E; Meier, D S; Calzetti, D

    2008-01-01

    Using new, high-resolution interferometric observations of the CO and HCN molecules, we directly compare the molecular and ionized components of the interstellar medium in the center of the nearby spiral galaxy IC342, on spatial scales of ~ 10pc. The morphology of the tracers suggests that the molecular gas flow caused by a large-scale stellar bar has been strongly affected by the mechanical feedback from recent star formation activity within the central 100pc in the nucleus of the galaxy. Possibly, stellar winds and/or supernova shocks originating in the nuclear star cluster have compressed, and likely pushed outward, the infalling molecular gas, thus significantly reducing the gas supply to the central 10pc. Although our analysis currently lacks kinematic confirmation due to the face-on orientation of IC342, the described scenario is supported by the generally observed repetitive nature of star formation in the nuclear star clusters of late-type spiral galaxies.

  20. Genistein, isoflavonoids in soybeans, prevents the formation of excess radiation-induced centrosomes via p21 up-regulation

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Mikio; Kato, Akihiro [Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Yoshida-konoe, Sakyo, Kyoto 606-8501 (Japan); Habu, Toshiyuki [Department of Radiation System Biology, Radiation Biology Center, Kyoto University, Kyoto 606-8501 (Japan); Komatsu, Kenshi, E-mail: komatsu@house.rbc.kyoto-u.ac.jp [Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Yoshida-konoe, Sakyo, Kyoto 606-8501 (Japan)

    2011-11-01

    The centrosome is a cytoplasmic organelle which duplicates once during each cell cycle, and the presence of excess centrosomes promote chromosome instability through chromosome missegregation following cytokinesis. Ionizing radiation (IR) can induce extra centrosomes by permitting the continuation of CDK2/Cyclin-A/E-mediated centrosome duplication when cells are arrested in the cell cycle after irradiation. The work described here shows that, in addition to IR, extra centrosomes were induced in human U2OS and mouse NIH3T3 cells after treatment with agents which include DNA adduct-forming chemicals: benzopyrene (BP), 4-nitroquinoline 1-oxide (4NQO), a DNA cross linker: cis-diamminedichloro-platinum (cisplatin), topoisomerase inhibitors: camptothecin, etoposide, genistein, and ultra-violet light (UV). These agents were divided into two categories with respect to the regulation of p21, which is an inhibitor of CDK2/Cyclin-A/E: specifically, p21 was up-regulated by an IR exposure and treatment with topoisomerase inhibitors. However, UV, BP, 4NQO and cisplatin down-regulated p21 below basal levels. When cells were irradiated with IR in combination with all of these agents, except genistein, enhanced induction of extra centrosomes was observed, regardless of the nature of p21 expression. Genistein significantly suppressed the frequency of IR-induced extra centrosomes in a dose-dependent manner, and 20 {mu}g/ml of genistein reduced this frequency to 66%. Consistent with this, genistein substantially up-regulated p21 expression over the induction caused by IR alone, while other agents down-regulated or marginally affected this. This suggests the inhibitory effect of genistein on the induction of extra centrosomes occurs through the inactivation of CDK2/Cyclin-A/E via p21 up-regulation. This hypothesis is supported by the observation that p21 knockdown with siRNA reduced the activity of CDK2/Cyclin-A/E and restored the enhanced effect of a combined treatment with genistein

  1. The Drosophila cell adhesion molecule Klingon is required for long-term memory formation and is regulated by Notch

    OpenAIRE

    Matsuno, Motomi; Horiuchi, Junjiro; Tully, Tim; Saitoe, Minoru

    2008-01-01

    The ruslan (rus) mutant was previously identified in a behavioral screen for mutants defective in long-lasting memory, which consists of two consolidated memory types, anesthesia-resistant memory, and protein synthesis-dependent long-term memory (LTM). We demonstrate here that rus is a new allele of klingon (klg), which encodes a homophilic cell adhesion molecule. Klg is acutely required for LTM but not anesthesia-resistant memory formation, and Klg expression increases upon LTM induction. LT...

  2. Cyclin-Dependent Kinase 5 Regulates Dendritic Spine Formation and Maintenance of Cortical Neuron in the Mouse Brain.

    Science.gov (United States)

    Mita, Naoki; He, Xiaojuan; Sasamoto, Kodai; Mishiba, Tomohide; Ohshima, Toshio

    2016-03-01

    Cyclin-dependent kinase 5 (Cdk5) activity is dependent on its association with 1 of 2 neuron-specific activators, p35 or p39. Cdk5 and its activators play an important role in brain development as well as higher functions like synaptic plasticity, learning, and memory. Reduction in p35 was reported in postmortem schizophrenia brain, in which reduced dendritic spine density was observed. Previous in vitro experiments have shown that Cdk5 is involved in dendritic spine formation, although in vivo evidence is limited. We examined dendritic spine formation in inducible-p35 conditional knockout (p35 cKO); p39 KO mice. When we deleted the p35 gene either during early postnatal days or at adult stage, we observed reduced spine densities of layer V neurons in the cerebral cortex and CA1 pyramidal neurons in the hippocampus. We further generated CA1-specific p35 conditional knockout (CA1-p35 cKO) mice and also CA1-p35 cKO; p39 KO mice in which have specific deletion of p35 in the CA1 region of hippocampus. We found a greater reduction in spine densities in CA1 pyramidal neurons in CA1-p35 cKO; p39 KO mice than in CA1-p35 cKO mice. These results indicate that dendritic spine formation and neuronal maintenance are dependent on Cdk5 activity.

  3. The regulation of star formation in cool-core clusters: imprints on the stellar populations of brightest cluster galaxies

    CERN Document Server

    Loubser, S I; Hoekstra, H; Mahdavi, A; Donahue, M; Bildfell, C; Voit, G M

    2015-01-01

    A fraction of brightest cluster galaxies (BCGs) shows bright emission in the UV and the blue part of the optical spectrum, which has been interpreted as evidence of recent star formation. Most of these results are based on the analysis of broadband photometric data. Here, we study the optical spectra of a sample of 19 BCGs hosted by X-ray luminous galaxy clusters at 0.15 < z < 0.3, a subset from the Canadian Cluster Comparison Project (CCCP) sample. We identify plausible star formation histories of the galaxies by fitting Simple Stellar Populations (SSPs) as well as composite populations, consisting of a young stellar component superimposed on an intermediate/old stellar component, to accurately constrain their star formation histories. We detect prominent young (~200 Myr) stellar populations in 4 of the 19 galaxies. Of the four, the BCG in Abell 1835 shows remarkable A-type stellar features indicating a relatively large population of young stars, which is extremely unusual even amongst star forming BCG...

  4. Numerical Simulations of Turbulent, Molecular Clouds Regulated by Radiation Feedback Forces I: Star Formation Rate and Efficiency

    CERN Document Server

    Raskutti, Sudhir; Skinner, M Aaron

    2016-01-01

    Radiation feedback from stellar clusters is expected to play a key role in setting the rate and efficiency of star formation in giant molecular clouds (GMCs). To investigate how radiation forces influence realistic turbulent systems, we have conducted a series of numerical simulations employing the {\\it Hyperion} radiation hydrodynamics solver, considering the regime that is optically thick to ultraviolet (UV) and optically thin to infrared (IR) radiation. Our model clouds cover initial surface densities between $\\Sigma_{\\rm cl,0} \\sim 10-300~M_{\\odot}~{\\rm pc^{-2}}$, with varying initial turbulence. We follow them through turbulent, self-gravitating collapse, formation of star clusters, and cloud dispersal by stellar radiation. All our models display a lognormal distribution of gas surface density $\\Sigma$; for an initial virial parameter $\\alpha_{\\rm vir,0} = 2$, the lognormal standard deviation is $\\sigma_{\\rm ln \\Sigma} = 1-1.5$ and the star formation rate coefficient $\\varepsilon_{\\rm ff,\\bar\\rho} = 0.3-...

  5. A role for the retinoblastoma protein as a regulator of mouse osteoblast cell adhesion: implications for osteogenesis and osteosarcoma formation.

    Directory of Open Access Journals (Sweden)

    Bernadette Sosa-García

    Full Text Available The retinoblastoma protein (pRb is a cell cycle regulator inactivated in most human cancers. Loss of pRb function results from mutations in the gene coding for pRb or for any of its upstream regulators. Although pRb is predominantly known as a cell cycle repressor, our data point to additional pRb functions in cell adhesion. Our data show that pRb regulates the expression of a wide repertoire of cell adhesion genes and regulates the assembly of the adherens junctions required for cell adhesion. We conducted our studies in osteoblasts, which depend on both pRb and on cell-to-cell contacts for their differentiation and function. We generated knockout mice in which the RB gene was excised specifically in osteoblasts using the cre-lox P system and found that osteoblasts from pRb knockout mice did not assemble adherens junction at their membranes. pRb depletion in wild type osteoblasts using RNAi also disrupted adherens junctions. Microarrays comparing pRb-expressing and pRb-deficient osteoblasts showed that pRb controls the expression of a number of cell adhesion genes, including cadherins. Furthermore, pRb knockout mice showed bone abnormalities consistent with osteoblast adhesion defects. We also found that pRb controls the function of merlin, a well-known regulator of adherens junction assembly, by repressing Rac1 and its effector Pak1. Using qRT-PCR, immunoblots, co-immunoprecipitation assays, and immunofluorescent labeling, we observed that pRb loss resulted in Rac1 and Pak1 overexpression concomitant with merlin inactivation by Pak1, merlin detachment from the membrane, and adherens junction loss. Our data support a pRb function in cell adhesion while elucidating the mechanism for this function. Our work suggests that in some tumor types pRb inactivation results in both a loss of cell cycle control that promotes initial tumor growth as well as in a loss of cell-to-cell contacts, which contributes to later stages of metastasis.

  6. YfbA, a Yersinia pestis Regulator Required for Colonization and Biofilm Formation in the Gut of Cat Fleas

    OpenAIRE

    Tam, Christina; Demke, Owen; Hermanas, Timothy; Mitchell,Anthony; Hendrickx, Antoni P. A.; Schneewind, Olaf

    2014-01-01

    For transmission to new hosts, Yersinia pestis, the causative agent of plague, replicates as biofilm in the foregut of fleas that feed on plague-infected animals or humans. Y. pestis biofilm formation has been studied in the rat flea; however, little is known about the cat flea, a species that may bridge zoonotic and anthroponotic plague cycles. Here, we show that Y. pestis infects and replicates as a biofilm in the foregut of cat fleas in a manner requiring hmsFR, two determinants for extrac...

  7. The master regulator for biofilm formation in Bacillus subtilis governs the expression of an operon encoding secreted proteins required for the assembly of complex multicellular communities.

    Energy Technology Data Exchange (ETDEWEB)

    Branda, Steven S. (Harvard Medical School, Cambridge, MA); Losick, Richard (Harvard University, Cambridge, MA); Kolter, Roberto (Harvard Medical School, Cambridge, MA); Kearns, Daniel B. (Harvard University, Cambridge, MA); Chu, Frances (Harvard University, Cambridge, MA)

    2005-08-01

    Wild strains of Bacillus subtilis are capable of forming architecturally complex communities of cells known as biofilms. Critical to biofilm formation is the eps operon, which is believed to be responsible for the biosynthesis of an exopolysaccharide that binds chains of cells together in bundles. We report that transcription of eps is under the negative regulation of SinR, a repressor that was found to bind to multiple sites in the regulatory region of the operon. Mutations in sinR bypassed the requirement in biofilm formation of two genes of unknown function, ylbF and ymcA, and sinI, which is known to encode an antagonist of SinR. We propose that these genes are members of a pathway that is responsible for counteracting SinR-mediated repression. We further propose that SinR is a master regulator that governs the transition between a planktonic state in which the bacteria swim as single cells in liquid or swarm in small groups over surfaces, and a sessile state in which the bacteria adhere to each other to form bundled chains and assemble into multicellular communities.

  8. Bacillus cereus ATCC 14579 RpoN (Sigma 54) Is a Pleiotropic Regulator of Growth, Carbohydrate Metabolism, Motility, Biofilm Formation and Toxin Production.

    Science.gov (United States)

    Hayrapetyan, Hasmik; Tempelaars, Marcel; Nierop Groot, Masja; Abee, Tjakko

    2015-01-01

    Sigma 54 is a transcriptional regulator predicted to play a role in physical interaction of bacteria with their environment, including virulence and biofilm formation. In order to study the role of Sigma 54 in Bacillus cereus, a comparative transcriptome and phenotypic study was performed using B. cereus ATCC 14579 WT, a markerless rpoN deletion mutant, and its complemented strain. The mutant was impaired in many different cellular functions including low temperature and anaerobic growth, carbohydrate metabolism, sporulation and toxin production. Additionally, the mutant showed lack of motility and biofilm formation at air-liquid interphase, and this correlated with absence of flagella, as flagella staining showed only WT and complemented strain to be highly flagellated. Comparative transcriptome analysis of cells harvested at selected time points during growth in aerated and static conditions in BHI revealed large differences in gene expression associated with loss of phenotypes, including significant down regulation of genes in the mutant encoding enzymes involved in degradation of branched chain amino acids, carbohydrate transport and metabolism, flagella synthesis and virulence factors. Our study provides evidence for a pleiotropic role of Sigma 54 in B. cereus supporting its adaptive response and survival in a range of conditions and environments.

  9. Bacillus cereus ATCC 14579 RpoN (Sigma 54 Is a Pleiotropic Regulator of Growth, Carbohydrate Metabolism, Motility, Biofilm Formation and Toxin Production.

    Directory of Open Access Journals (Sweden)

    Hasmik Hayrapetyan

    Full Text Available Sigma 54 is a transcriptional regulator predicted to play a role in physical interaction of bacteria with their environment, including virulence and biofilm formation. In order to study the role of Sigma 54 in Bacillus cereus, a comparative transcriptome and phenotypic study was performed using B. cereus ATCC 14579 WT, a markerless rpoN deletion mutant, and its complemented strain. The mutant was impaired in many different cellular functions including low temperature and anaerobic growth, carbohydrate metabolism, sporulation and toxin production. Additionally, the mutant showed lack of motility and biofilm formation at air-liquid interphase, and this correlated with absence of flagella, as flagella staining showed only WT and complemented strain to be highly flagellated. Comparative transcriptome analysis of cells harvested at selected time points during growth in aerated and static conditions in BHI revealed large differences in gene expression associated with loss of phenotypes, including significant down regulation of genes in the mutant encoding enzymes involved in degradation of branched chain amino acids, carbohydrate transport and metabolism, flagella synthesis and virulence factors. Our study provides evidence for a pleiotropic role of Sigma 54 in B. cereus supporting its adaptive response and survival in a range of conditions and environments.

  10. Effects of Arg-Gly-Asp-modified elastin-like polypeptide on pseudoislet formation via up-regulation of cell adhesion molecules and extracellular matrix proteins.

    Science.gov (United States)

    Lee, Kyeong-Min; Jung, Gwon-Soo; Park, Jin-Kyu; Choi, Seong-Kyoon; Jeon, Won Bae

    2013-03-01

    Extracellular matrix (ECM) plays an important role in controlling the β-cell morphology, survival and insulin secretary functions. An RGD-modified elastin-like polypeptide (RGD-ELP), TGPG[VGRGD(VGVPG)(6)](20)WPC, has been reported previously as a bioactive matrix. In this study, to investigate whether RGD-ELP affects β-cell growth characteristics and insulin secretion, β-TC6 cells were cultured on the RGD-ELP coatings prepared via thermally induced phase transition. On RGD-ELP, β-TC6 cells clustered into an islet-like architecture with high cell viability. Throughout 7days' culture, the proliferation rate of the cells within a pseudoislet was similar to that of monolayer culture. Under high glucose (25mM), β-TC6 pseudoislets showed up-regulated insulin gene expression and exhibited glucose-stimulated insulin secretion. Importantly, the mRNA and protein abundances of cell adhesion molecules (CAM) E-cadherin and connexin-36 were much higher in pseudoislets than in monolayer cells. The siRNA-mediated inhibition of E-cadherin or connexin-36 expression severely limited pseudoislet formation. In addition, the mRNA levels of collagen types I and IV, fibronectin and laminin were significantly elevated in pseudoislets. The results suggest that RGD-ELP promotes pseudoislet formation via up-regulation of the CAM and ECM components. The functional roles of RGD-ELP are discussed in respect of its molecular composition.

  11. Ubiquitination of HTLV-I Tax in response to DNA damage regulates nuclear complex formation and nuclear export

    Directory of Open Access Journals (Sweden)

    Marriott Susan J

    2007-12-01

    Full Text Available Abstract Background The HTLV-I oncoprotein, Tax, is a pleiotropic protein whose activity is partially regulated by its ability to interact with, and perturb the functions of, numerous cellular proteins. Tax is predominantly a nuclear protein that localizes to nuclear foci known as Tax Speckled Structures (TSS. We recently reported that the localization of Tax and its interactions with cellular proteins are altered in response to various forms of genotoxic and cellular stress. The level of cytoplasmic Tax increases in response to stress and this relocalization depends upon the interaction of Tax with CRM1. Cellular pathways and signals that regulate the subcellular localization of Tax remain to be determined. However, post-translational modifications including sumoylation and ubiquitination are known to influence the subcellular localization of Tax and its interactions with cellular proteins. The sumoylated form of Tax exists predominantly in the nucleus while ubiquitinated Tax exists predominantly in the cytoplasm. Therefore, we hypothesized that post-translational modifications of Tax that occur in response to DNA damage regulate the localization of Tax and its interactions with cellular proteins. Results We found a significant increase in mono-ubiquitination of Tax in response to UV irradiation. Mutation of specific lysine residues (K280 and K284 within Tax inhibited DNA damage-induced ubiquitination. In contrast to wild-type Tax, which undergoes transient nucleocytoplasmic shuttling in response to DNA damage, the K280 and K284 mutants were retained in nuclear foci following UV irradiation and remained co-localized with the cellular TSS protein, sc35. Conclusion This study demonstrates that the localization of Tax, and its interactions with cellular proteins, are dynamic following DNA damage and depend on the post-translational modification status of Tax. Specifically, DNA damage induces the ubiquitination of Tax at K280 and K284

  12. Coenzyme Q(10)--its role as a prooxidant in the formation of superoxide anion/hydrogen peroxide and the regulation of the metabolome.

    Science.gov (United States)

    Linnane, Anthony W; Kios, Michael; Vitetta, Luis

    2007-06-01

    Coenzyme Q10 plays a central role in cellular bioenergy generation and its regulation. Closed membrane systems generate a proton motive force to create transient localized bio-capacitors; the captured energy is used for the synthesis of mitochondrial ATP but also for many other processes, such as metabolite translocations, nerve conduction and a host of other bioenergy requiring processes. Coenzyme Q10 plays a key role in many of these sub-cellular membrane energy generating systems. Integral to this phenomenon is the prooxidant role of coenzyme Q10 in generating the major superoxide anion/hydrogen peroxide second messenger system. This messenger system, largely but not exclusively, arises from coenzyme Q10 semiquinone function; it contributes to the regulation of sub-cellular redox potential levels; transcription/gene expression control; is essential for modulated protein turnover and activation; mediates hormone and growth factor extracellular signaling. The regulated prooxidant formation of the superoxide anion/H2O2 second messenger system is essential for the normal physiological function of the metabolome. The normally functioning metabolome is the expression of a finely tuned dynamic equilibrium comprised of thousands of anabolic and catabolic reactions and all cellular signaling systems must be finely regulated. There is still much to be learnt about the up/down regulation of the H2O2 messenger system. The concept that superoxide anion/H2O2 cause random macromolecular damage is rebutted. The administration of antioxidants to quench the inferred toxicity of these compounds as a therapy for age associated diseases is unsupported by extant mammalian clinical trials and should be subject to serious re-evaluation. The role of ascorbic acid as a beneficial hydrogen peroxide prodrug is discussed.

  13. Enhanced expression of glucose-regulated protein 78 correlates with malondialdehyde levels during the formation of liver cirrhosis in rats

    OpenAIRE

    Zhang, Yun; Zhang, Huiying; Zhao, Zhongfu; Lv, Minli; Jia, Jiantao; Zhang, Lili; Tian, Xiaoxia; Chen, Yunxia; Li, Baohong; LIU, MINGSHE; Han, Dewu; Ji, Cheng

    2015-01-01

    The aim of the present study was to explore the role of glucose-regulated protein 78 (GRP78) in the development of liver cirrhosis promoted by intestinal endotoxemia in rats. Fifty-one male Wistar rats were randomly divided into the liver cirrhosis 4-week, 6-week and 8-week groups and the normal control group at each time point. Liver cirrhosis was induced by employing multiple pathogenic factors in the rats. Blood and liver tissues were collected. The levels of alanine aminotransferase (ALT)...

  14. NOA1 Functions in a Temperature-Dependent Manner to Regulate Chlorophyll Biosynthesis and Rubisco Formation in Rice

    OpenAIRE

    Yang, Qiaosong; He, Han; Li, Heying; Tian, Hua; Zhang, Jianjun; Zhai, Liguang; Chen, Jiandong; Wu, Hong; Yi, Ganjun; He, Zheng-Hui; Peng, Xinxiang

    2011-01-01

    NITRIC OXIDE-ASSOCIATED1 (NOA1) encodes a circularly permuted GTPase (cGTPase) known to be essential for ribosome assembly in plants. While the reduced chlorophyll and Rubisco phenotypes were formerly noticed in both NOA1-supressed rice and Arabidopsis, a detailed insight is still necessary. In this study, by using RNAi transgenic rice, we further demonstrate that NOA1 functions in a temperature-dependent manner to regulate chlorophyll and Rubisco levels. When plants were grown at 30°C, the c...

  15. MEG3 long noncoding RNA regulates the TGF-β pathway genes through formation of RNA-DNA triplex structures

    OpenAIRE

    Mondal, Tanmoy; Subhash, Santhilal; Vaid, Roshan; Enroth, Stefan; Uday, Sireesha; Reinius, Björn; Mitra, Sanhita; Mohammed, Arif; James, Alva Rani; Hoberg, Emily; Moustakas, Aristidis; Gyllensten, Ulf; Steven J M Jones; Gustafsson, Claes M.; Sims, Andrew H.

    2015-01-01

    Long noncoding RNAs (lncRNAs) regulate gene expression by association with chromatin, but how they target chromatin remains poorly understood. We have used chromatin RNA immunoprecipitation-coupled high-throughput sequencing to identify 276 lncRNAs enriched in repressive chromatin from breast cancer cells. Using one of the chromatin-interacting lncRNAs, MEG3, we explore the mechanisms by which lncRNAs target chromatin. Here we show that MEG3 and EZH2 share common target genes, including the T...

  16. Regulation of phytohormones on root primordium initiation and adventitious root formation in the etiolated shoots of Paeonia suffruticosa 'Yinfen Jinlin'

    Institute of Scientific and Technical Information of China (English)

    Zeng Duan-xiang; Yin Wei-lun; Zhao Xiao-qing; Wang Hua-fang

    2006-01-01

    Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mechnisms of the adventitious rooting and the regulation of rooting processes are the principles and techniques of plant propagation and improvement. Microstmctures and fluctuations of phytohormones in the adventitious rooting were studied with the etiolated softwood shoots of Paeonia suffruticosa 'Yinfen Jinlin'. There are no pre-primordia in the shoots of the cultivar. Adventitious roots are produced in five stages: shoot selection, primordium initiation, primordium growth, conducting tissue differentiation and root protrusion. Primordia initiated in the cortex. The contents of the endogenous hormones, IAA, ABA and GA, were 5.842, 0.873 and 1.043to GA, CTK and ABA clearly increased at the stage of primordium initiation, while they showed low levels at the stages of primordium growth. The ratios were restored at the shoot levels at the stage of root protrusion. IBA provoked primordia initiation in the cortex, the vascular cambium, the pith and even in the callus induced on the base of shoots. IAA levels in the treated shoots increased gradually to its highest level (three times of control) at the stage of conducting tissue differentiation. The ratios of IAA to GA, CTK and ABA clearly decreased at the stage of primordium initiation. The ratio of IAA to ABA is regulated at 10:1.

  17. The four-herb Chinese medicine ANBP enhances wound healing and inhibits scar formation via bidirectional regulation of transformation growth factor pathway.

    Science.gov (United States)

    Hou, Qian; He, Wen-Jun; Hao, Hao-Jie; Han, Qing-Wang; Chen, Li; Dong, Liang; Liu, Jie-Jie; Li, Xiang; Zhang, Ya-Jing; Ma, Ying-Zhi; Han, Wei-Dong; Fu, Xiao-Bing

    2014-01-01

    The four-herb Chinese medicine ANBP is a pulverized mixture of four herbs including Agrimonia Eupatoria (A), Nelumbo Nucifera Gaertn (N), Boswellia Carteri (B) and Pollen Typhae Angustifoliae (P). The combination of the four herbs was first described in Chinese canonical medicine about 2000 years ago for treatment of various trauma disorders, such as hemostasis, antiinflammatory, analgesia, and wound healing, etc. However, the precise mechanisms of ANBP are still unclear. In our study, using rabbit ear hypertrophic scar models of full-thickness skin defect, we showed that local ANBP treatment not only significantly enhanced wound healing by relieving inflammation, increasing formation of granulation tissue and accelerating re-epithelialization, but also reduced scar formation by decreasing collagen production, protuberant height and volume of scars, and increasing collagen maturity. We demonstrated that these effects of ANBP are associated with transforming growth factor (TGF)-β1-mediated signalling pathways through Smad-dependent pathways. ANBP treatment significantly increased expression of TGF-β1 and Smad2/3 mRNA at the early stage of wound healing, and led to markedly decrease expression of TGF-β1 and Smad2/3 compared with the control group after 14 days post-wounding. Taken together, our results defined a bidirectional regulation role of ANBP for TGF-β1/Smad pathway in promoting wound healing and alleviating scar formation, which may be an effective therapy for human wounds at the earliest stage.

  18. The four-herb Chinese medicine ANBP enhances wound healing and inhibits scar formation via bidirectional regulation of transformation growth factor pathway.

    Directory of Open Access Journals (Sweden)

    Qian Hou

    Full Text Available The four-herb Chinese medicine ANBP is a pulverized mixture of four herbs including Agrimonia Eupatoria (A, Nelumbo Nucifera Gaertn (N, Boswellia Carteri (B and Pollen Typhae Angustifoliae (P. The combination of the four herbs was first described in Chinese canonical medicine about 2000 years ago for treatment of various trauma disorders, such as hemostasis, antiinflammatory, analgesia, and wound healing, etc. However, the precise mechanisms of ANBP are still unclear. In our study, using rabbit ear hypertrophic scar models of full-thickness skin defect, we showed that local ANBP treatment not only significantly enhanced wound healing by relieving inflammation, increasing formation of granulation tissue and accelerating re-epithelialization, but also reduced scar formation by decreasing collagen production, protuberant height and volume of scars, and increasing collagen maturity. We demonstrated that these effects of ANBP are associated with transforming growth factor (TGF-β1-mediated signalling pathways through Smad-dependent pathways. ANBP treatment significantly increased expression of TGF-β1 and Smad2/3 mRNA at the early stage of wound healing, and led to markedly decrease expression of TGF-β1 and Smad2/3 compared with the control group after 14 days post-wounding. Taken together, our results defined a bidirectional regulation role of ANBP for TGF-β1/Smad pathway in promoting wound healing and alleviating scar formation, which may be an effective therapy for human wounds at the earliest stage.

  19. Proper Actin Ring Formation and Septum Constriction Requires Coordinated Regulation of SIN and MOR Pathways through the Germinal Centre Kinase MST-1

    Science.gov (United States)

    Heilig, Yvonne; Dettmann, Anne; Mouriño-Pérez, Rosa R.; Schmitt, Kerstin; Valerius, Oliver; Seiler, Stephan

    2014-01-01

    Nuclear DBF2p-related (NDR) kinases constitute a functionally conserved protein family of eukaryotic regulators that control cell division and polarity. In fungi, they function as effector kinases of the morphogenesis (MOR) and septation initiation (SIN) networks and are activated by pathway-specific germinal centre (GC) kinases. We characterized a third GC kinase, MST-1, that connects both kinase cascades. Genetic and biochemical interactions with SIN components and life cell imaging identify MST-1 as SIN-associated kinase that functions in parallel with the GC kinase SID-1 to activate the SIN-effector kinase DBF-2. SID-1 and MST-1 are both regulated by the upstream SIN kinase CDC-7, yet in an opposite manner. Aberrant cortical actomyosin rings are formed in Δmst-1, which resulted in mis-positioned septa and irregular spirals, indicating that MST-1-dependent regulation of the SIN is required for proper formation and constriction of the septal actomyosin ring. However, MST-1 also interacts with several components of the MOR network and modulates MOR activity at multiple levels. MST-1 functions as promiscuous enzyme and also activates the MOR effector kinase COT-1 through hydrophobic motif phosphorylation. In addition, MST-1 physically interacts with the MOR kinase POD-6, and dimerization of both proteins inactivates the GC kinase hetero-complex. These data specify an antagonistic relationship between the SIN and MOR during septum formation in the filamentous ascomycete model Neurospora crassa that is, at least in part, coordinated through the GC kinase MST-1. The similarity of the SIN and MOR pathways to the animal Hippo and Ndr pathways, respectively, suggests that intensive cross-communication between distinct NDR kinase modules may also be relevant for the homologous NDR kinases of higher eukaryotes. PMID:24762679

  20. Allegheny County Municipal Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the municipal boundaries in Allegheny County. Data was created to portray the boundaries of the 130 Municipalities in Allegheny County the...

  1. County Political Boundaries (National)

    Data.gov (United States)

    Department of Transportation — County boundaries with political limit - boundaries extending into the ocean (NTAD 2015). The TIGER/Line shapefiles and related database files (.dbf) are an extract...

  2. HUD GIS Boundary Files

    Data.gov (United States)

    Department of Housing and Urban Development — The HUD GIS Boundary Files are intended to supplement boundary files available from the U.S. Census Bureau. The files are for community planners interested in...

  3. State Agency Administrative Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This database comprises 28 State agency boundaries and point of contact. The Kansas Geological Survey collected legal descriptions of the boundaries for various...

  4. The histone H3K9 methylation and RNAi pathways regulate normalnucleolar and repeated DNA organization by inhibiting formation ofextrachromosomal DNAs

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Jamy C.; Karpen, Gary H.

    2006-06-15

    In order to identify regulators of nuclear organization, Drosophila mutants in the Su(var)3-9 histone H3K9 methyltransferase, RNAi pathway components, and other regulators of heterochromatin-mediated gene silencing were examined for altered nucleoli and positioning of repeated DNAs. Animals lacking components of the H3K9 methylation and RNAi pathways contained disorganized nucleoli, ribosomal DNA (rDNA) and satellite DNAs. The levels of H3K9 dimethylation (H3K9me2) in chromatin associated with repeated DNAs decreased dramatically in Su(var)3-9 and dcr-2 (dicer-2) mutant tissues compared to wild type. We also observed a substantial increase in extrachromosomal repeated DNAs in mutant tissues. The disorganized nucleolus phenotype depends on the presence of Ligase 4 (Lig4), and ecc DNA formation is not induced by removal of cohesin. We conclude that H3K9 methylation of rDNA and satellites, maintained by Su(var)3-9, HP1, and the RNAi pathway, is necessary for the structural stability of repeated DNAs, which is mediated through suppression of non-homologous end joining (NHEJ). These results suggest a mechanism for how local chromatin structure can regulate genome stability, and the organization of chromosomal elements and nuclear organelles.

  5. miR-155 acts as an anti-inflammatory factor in atherosclerosis-associated foam cell formation by repressing calcium-regulated heat stable protein 1.

    Science.gov (United States)

    Li, Xiaoyi; Kong, Deyong; Chen, Heming; Liu, Shuiyi; Hu, Hui; Wu, Tangwei; Wang, Jing; Chen, Weiqun; Ning, Yong; Li, Yong; Lu, Zhongxin

    2016-01-01

    Atherosclerosis (AS) is chronic inflammation in response to lipid accumulation. MicroRNA-155 (miR-155) is being increasingly studied to evaluate its potential as diagnostic biomarkers and therapeutic targets in many diseases. However, delineating the role of miR-155 in AS remains difficult. Here, we detected constitutive expression of several microRNAs (miRNAs) possibly associated with cardiovascular disease in foam cells and clinical specimens from patients with AS. Among them, we found that the level of miR-155 in foam cells was the most significantly elevated in a dose- and time-dependent manner. In addition, the expression of miR-155 was elevated in the plasma and plaque of patients with AS. We also reported for the first time that miR-155 targets calcium-regulated heat stable protein 1 (CARHSP1), which regulates the stability of tumor necrosis factor alpha (TNF-α) mRNA. Furthermore, we investigated the mechanism by which the miR-155 level is elevated. miR-155 upregulation is due to transcriptional regulation by nuclear factor (NF)-κB, which is activated by the inflammatory factor TNF-α. In summary, increased miR-155 relieves chronic inflammation by a negative feedback loop and plays a protective role during atherosclerosis-associated foam cell formation by signaling through the miR-155-CARHSP1-TNF-α pathway. PMID:26899994

  6. Regulation of Pattern Formation and Gene Amplification During Drosophila Oogenesis by the miR-318 microRNA

    DEFF Research Database (Denmark)

    Ge, Wanzhong; Deng, Qiannan; Guo, Ting;

    2015-01-01

    Pattern formation during epithelial development requires the coordination of multiple signaling pathways. Here, we investigate the functions of an ovary-enriched miRNA, miR-318, in epithelial development during Drosophila oogenesis. miR-318 maternal loss-of-function mutants were female sterile...... and laid eggs with abnormal morphology. Removal of miR-318 disrupted the dorsal-anterior follicle cell patterning, resulting in abnormal dorsal appendages. miR-318 mutant females also produced thin and fragile eggshells, due to impaired chorion gene amplification. We provide evidence that the ecdysone...... signaling pathway activates expression of miR-318 and that miR-318 cooperates with Tramtrack69 (Ttk69) to control the switch from endocycling to chorion gene amplification during differentiation of the follicular epithelium. The multiple functions of miR-318 in oogenesis illustrate the importance of mi...

  7. GlgS, described previously as a glycogen synthesis control protein, negatively regulates motility and biofilm formation in Escherichia coli.

    Science.gov (United States)

    Rahimpour, Mehdi; Montero, Manuel; Almagro, Goizeder; Viale, Alejandro M; Sevilla, Ángel; Cánovas, Manuel; Muñoz, Francisco J; Baroja-Fernández, Edurne; Bahaji, Abdellatif; Eydallin, Gustavo; Dose, Hitomi; Takeuchi, Rikiya; Mori, Hirotada; Pozueta-Romero, Javier

    2013-06-15

    Escherichia coli glycogen metabolism involves the regulation of glgBXCAP operon expression and allosteric control of the GlgC [ADPG (ADP-glucose) pyrophosphorylase]-mediated catalysis of ATP and G1P (glucose-1-phosphate) to ADPG linked to glycogen biosynthesis. E. coli glycogen metabolism is also affected by glgS. Though the precise function of the protein it encodes is unknown, its deficiency causes both reduced glycogen content and enhanced levels of the GlgC-negative allosteric regulator AMP. The transcriptomic analyses carried out in the present study revealed that, compared with their isogenic BW25113 wild-type strain, glgS-null (ΔglgS) mutants have increased expression of the operons involved in the synthesis of type 1 fimbriae adhesins, flagella and nucleotides. In agreement, ΔglgS cells were hyperflagellated and hyperfimbriated, and displayed elevated swarming motility; these phenotypes all reverted to the wild-type by ectopic glgS expression. Also, ΔglgS cells accumulated high colanic acid content and displayed increased ability to form biofilms on polystyrene surfaces. F-driven conjugation based on large-scale interaction studies of glgS with all the non-essential genes of E. coli showed that deletion of purine biosynthesis genes complement the glycogen-deficient, high motility and high biofilm content phenotypes of ΔglgS cells. Overall the results of the present study indicate that glycogen deficiency in ΔglgS cells can be ascribed to high flagellar propulsion and high exopolysaccharide and purine nucleotides biosynthetic activities competing with GlgC for the same ATP and G1P pools. Supporting this proposal, glycogen-less ΔglgC cells displayed an elevated swarming motility, and accumulated high levels of colanic acid and biofilm. Furthermore, glgC overexpression reverted the glycogen-deficient, high swarming motility, high colanic acid and high biofilm content phenotypes of ΔglgS cells to the wild-type. As on the basis of the present study Glg

  8. Bordetella pertussis fim3 gene regulation by BvgA: phosphorylation controls the formation of inactive vs. active transcription complexes.

    Science.gov (United States)

    Boulanger, Alice; Moon, Kyung; Decker, Kimberly B; Chen, Qing; Knipling, Leslie; Stibitz, Scott; Hinton, Deborah M

    2015-02-10

    Two-component systems [sensor kinase/response regulator (RR)] are major tools used by microorganisms to adapt to environmental conditions. RR phosphorylation is typically required for gene activation, but few studies have addressed how and if phosphorylation affects specific steps during transcription initiation. We characterized transcription complexes made with RNA polymerase and the Bordetella pertussis RR, BvgA, in its nonphosphorylated or phosphorylated (BvgA∼P) state at P(fim3), the promoter for the virulence gene fim3 (fimbrial subunit), using gel retardation, potassium permanganate and DNase I footprinting, cleavage reactions with protein conjugated with iron bromoacetamidobenzyl-EDTA, and in vitro transcription. Previous work has shown that the level of nonphosphorylated BvgA remains high in vivo under conditions in which BvgA is phosphorylated. Our results here indicate that surprisingly both BvgA and BvgA∼P form open and initiating complexes with RNA polymerase at P(fim3). However, phosphorylation of BvgA is needed to generate the correct conformation that can transition to competent elongation. Footprints obtained with the complexes made with nonphosphorylated BvgA are atypical; while the initiating complex with BvgA synthesizes short RNA, it does not generate full-length transcripts. Extended incubation of the BvgA/RNA polymerase initiated complex in the presence of heparin generates a stable, but defective species that depends on the initial transcribed sequence of fim3. We suggest that the presence of nonphosphorylated BvgA down-regulates P(fim3) activity when phosphorylated BvgA is present and may allow the bacterium to quickly adapt to the loss of inducing conditions by rapidly eliminating P(fim3) activation once the signal for BvgA phosphorylation is removed.

  9. Watershed Boundaries - Watershed Boundary Database for Montana

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This data set is a complete digital hydrologic unit boundary layer of the Subbasins (8-digit), Watersheds (10-digit), and Subwatersheds (12-digit) for Montana. This...

  10. Campylobacter jejuni CsrA complements an Escherichia coli csrA mutation for the regulation of biofilm formation, motility and cellular morphology but not glycogen accumulation

    Directory of Open Access Journals (Sweden)

    Fields Joshua A

    2012-10-01

    Full Text Available Abstract Background Although Campylobacter jejuni is consistently ranked as one of the leading causes of bacterial diarrhea worldwide, the mechanisms by which C. jejuni causes disease and how they are regulated have yet to be clearly defined. The global regulator, CsrA, has been well characterized in several bacterial genera and is known to regulate a number of independent pathways via a post transcriptional mechanism, but remains relatively uncharacterized in the genus Campylobacter. Previously, we reported data illustrating the requirement for CsrA in several virulence related phenotypes of C. jejuni strain 81–176, indicating that the Csr pathway is important for Campylobacter pathogenesis. Results We compared the Escherichia coli and C. jejuni orthologs of CsrA and characterized the ability of the C. jejuni CsrA protein to functionally complement an E. coli csrA mutant. Phylogenetic comparison of E. coli CsrA to orthologs from several pathogenic bacteria demonstrated variability in C. jejuni CsrA relative to the known RNA binding domains of E. coli CsrA and in several amino acids reported to be involved in E. coli CsrA-mediated gene regulation. When expressed in an E. coli csrA mutant, C. jejuni CsrA succeeded in recovering defects in motility, biofilm formation, and cellular morphology; however, it failed to return excess glycogen accumulation to wild type levels. Conclusions These findings suggest that C. jejuni CsrA is capable of efficiently binding some E. coli CsrA binding sites, but not others, and provide insight into the biochemistry of C. jejuni CsrA.

  11. The Rim101p/PacC pathway and alkaline pH regulate pattern formation in yeast colonies.

    Science.gov (United States)

    Piccirillo, Sarah; White, Melissa G; Murphy, Jeffrey C; Law, Douglas J; Honigberg, Saul M

    2010-03-01

    Multicellular organisms utilize cell-to-cell signals to build patterns of cell types within embryos, but the ability of fungi to form organized communities has been largely unexplored. Here we report that colonies of the yeast Saccharomyces cerevisiae formed sharply divided layers of sporulating and nonsporulating cells. Sporulation initiated in the colony's interior, and this region expanded upward as the colony matured. Two key activators of sporulation, IME1 and IME2, were initially transcribed in overlapping regions of the colony, and this overlap corresponded to the initial sporulation region. The development of colony sporulation patterns depended on cell-to-cell signals, as demonstrated by chimeric colonies, which contain a mixture of two strains. One such signal is alkaline pH, mediated through the Rim101p/PacC pathway. Meiotic-arrest mutants that increased alkali production stimulated expression of an early meiotic gene in neighboring cells, whereas a mutant that decreased alkali production (cit1Delta) decreased this expression. Addition of alkali to colonies accelerated the expansion of the interior region of sporulation, whereas inactivation of the Rim101p pathway inhibited this expansion. Thus, the Rim101 pathway mediates colony patterning by responding to cell-to-cell pH signals. Cell-to-cell signals coupled with nutrient gradients may allow efficient spore formation and spore dispersal in natural environments. PMID:20038633

  12. Formation of post-confluence structure in human parotid gland acinar cells on PLGA through regulation of E-cadherin.

    Science.gov (United States)

    Chan, Yen-Hui; Huang, Tsung-Wei; Chou, Ya-Shuan; Hsu, Sheng-Hao; Su, Wei-Fang; Lou, Pei-Jen; Young, Tai-Horng

    2012-01-01

    As a potential solution for patients to retrieve their lost salivary gland functions, tissue engineering of an auto-secretory device is profoundly needed. Under serum-free environment, primary human parotid gland acinar (PGAC) cells can be obtained. After reaching confluence, PGAC cells spontaneously form three-dimension (3D) cell aggregations, termed post-confluence structure (PCS), and change their behaviors. Poly (lactic-co-glycolic acid) (PLGA) has been widely used in the field of biomedical applications because of its biodegradable properties for desired functions. Nonetheless, the role of PLGA in facilitating PGAC cells to form PCS has seldom been explored to recover epithelial characteristics. In this study, PGAC cells were found to have a greater tendency to form PCS on PLGA than on tissue culture polystyrene (TCPS). By tracing cell migration paths and modulating E-cadherin activity with specific inhibitor or antibody, we demonstrated that the static force of homophilic interaction on surfaces of individual cells, but not the dynamics of cell migration, played a more important role in PCS formation. Thus, PLGA was successfully confirmed to support PGAC cells to form more PCS through the effects on enhancing E-cadherin expression, which is associated with FAK/ILK/Snail expression in PGAC cells. This result indicates that selective appropriate biomaterials may be potentially useful in generating 3D PCS on two-dimension (2D) substrate without fabricating a complex 3D scaffold.

  13. Formation and Regulation Mechanism of Adaptive Response in Nematode Caenorhabditis elegans%秀丽线虫适应响应的形成与调控机理

    Institute of Scientific and Technical Information of China (English)

    范孟雪; 王大勇

    2011-01-01

    Besides environmental exposure evaluation, model animal of Caenorhabditis elegans has also been used in the studies of formation and regulation mechanism of adaptive response in environmental toxicology. In this review, three types of adaptive response existed in C. Elegans were introduced, which are hormesis, cross-adaptation, and dietary restriction. Six known factors influencing the formation of adaptive response were analyzed. The possible mechanisms explaining adaptive response formation were discussed. Especially, the important roles of anti-oxidation system, heatshock, metallothioneins, and ghitathione in regulating the formation of adaptive response were summarized. On these bases, the questions need to be further solved, the contributions of adaptive response studies in C. Elegans to toxicology, and the suggestions for further studies on adaptive response in C. Elegans were discussed.%除了环境暴露评价,在环境毒理学研究中模式动物秀丽线虫也已经被应用于适应响应形成及其调控机理研究.在综述中,系统介绍了秀丽线虫中存在的几种形式毒物诱发的适应响应,即同一因素适应响应、交叉适应响应与特殊形式的适应响应;讨论了目前已经揭示出的6种影响适应响应形成因素;分析了适应响应形成可能机制,即抗氧化应激体系、热激蛋白、金属硫蛋白与谷胱苷肽在适应响应形成中具有的各种重要功能.在此基础上,分析了秀丽线虫适应响应研究中存在的问题,讨论了该方面工作对于毒理学研究的重要意义,并对未来的研究工作进行了展望.

  14. Kaiso is a key regulator of spleen germinal center formation by repressing Bcl6 expression in splenocytes

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Dong-In; Yoon, Jae-Hyeon; Kim, Min-Kyeong; An, Haemin; Kim, Min-Young; Hur, Man-Wook, E-mail: mwhur2@yuhs.ac

    2013-12-13

    Highlights: •Knockout of Kaiso results in concordant high expression of Bcl6 and c-Myc in spleen. •Kaiso binds the Bcl6 promoter and represses Bcl6 transcription by recruiting NCoR. •Upregulated Bcl6 increases splenocyte proliferation and causes large diffused GC. •Cell cycle-inhibition genes such as Cdkn1b and Cdkn1a are repressed by Bcl6. -- Abstract: Kaiso was previously described as a methylated DNA-binding protein and a transcription repressor interacting with the corepressor protein complex NCoR. In the current study, we show that generation-3 Kaiso knockout mice show a phenotype of splenomegaly and large diffused germinal centers (GC). In the spleens of Kaiso knockout mice, Bcl6 (a transcriptional repressor that plays a critical role in GC development in spleen) and c-Myc were highly expressed, while the cell cycle arrest genes p27 (CDKN1B), p21 (CDKN1A) and Gadd45a were downregulated. Chromatin immunoprecipitation (ChIP) and transcription assays suggested that Kaiso represses Bcl6 expression, and in Kaiso knockout mice, derepressed Bcl6 increased cell proliferation by suppressing p27 (CDKN1B), p21 (CDKN1A) and Gadd45a, while upregulating the oncogene c-Myc. Further evidence for Kaiso regulation of splenomegaly was provided by B lymphocyte Ramos cells, in which ectopic KAISO repressed BCL6 and c-MYC expression, while concomitantly increasing the expression of the cell cycle arrestors p21, p27 and Gadd45a. In summary, derepressed Bcl6 expression may be responsible for increases in GC cell proliferation and splenomegaly of Kaiso knockout mice.

  15. BMP-2 regulates the formation of oral sulcus in mouse tongue by altering the balance between TIMP-1 and MMP-13.

    Science.gov (United States)

    Fukui, Tadayoshi; Suga, Takeo; Iida, Ryo-Hei; Morito, Mitsuhiko; Luan, Xianghong; Diekwisch, Thomas G H; Nakamura, Yoshiki; Yamane, Akira

    2010-08-01

    The aim of this study is to investigate whether BMP-2 regulates the oral sulcus formation of mouse embryonic tongue by modifying the expression of TIMP and MMP. The BMP-2 siRNA induced a 180% increase in the depth of oral sulcus cavity (P sulcus into the mesenchymal tissues consisting of tongue floor, whereas the recombinant BMP-2 suppressed the process in the organ culture system of mouse embryonic tongue. The BMP-2 siRNA induced a 60% decrease in the expression of TIMP-1 mRNA (P sulcus in the BMP-2 siRNA treated mandibles. The recombinant BMP-2 induced a 220% increases in the expression of TIMP-1 mRNA and the area of the immunostaining for TIMP-1 around the oral sulcus was larger in the mandibles treated with the recombinant BMP-2 than the vehicle. The BMP-2 siRNA induced a 60% increase in the expression of MMP-13 protein and a marked increase in the staining intensity for MMP-13 was observed in the epithelial region of the BMP-2 siRNA treated mandibles. The recombinant BMP-2 induced a 70% decrease in the expression of MMP-13 mRNA and the decrease was mainly observed in the tissues around oral sulcus. The expressions of BMP-2, TIMP-1, and MMP-13 were verified in the tissues around in vivo developing oral sulcus at E11, 12, and 13 by immunohistochemistry. These results suggest that BMP-2 regulates the formation of oral sulcus by altering the balance between TIMP-1 and MMP-13.

  16. Evidence for myoblast-extrinsic regulation of slow myosin heavy chain expression during muscle fiber formation in embryonic development.

    Science.gov (United States)

    Cho, M; Webster, S G; Blau, H M

    1993-05-01

    Vertebrate muscles are composed of an array of diverse fast and slow fiber types with different contractile properties. Differences among fibers in fast and slow MyHC expression could be due to extrinsic factors that act on the differentiated myofibers. Alternatively, the mononucleate myoblasts that fuse to form multinucleated muscle fibers could differ intrinsically due to lineage. To distinguish between these possibilities, we determined whether the changes in proportion of slow fibers were attributable to inherent differences in myoblasts. The proportion of fibers expressing slow myosin heavy chain (MyHC) was found to change markedly with time during embryonic and fetal human limb development. During the first trimester, a maximum of 75% of fibers expressed slow MyHC. Thereafter, new fibers formed which did not express this MyHC, so that the proportion of fibers expressing slow MyHC dropped to approximately 3% of the total by midgestation. Several weeks later, a subset of the new fibers began to express slow MyHC and from week 30 of gestation through adulthood, approximately 50% of fibers were slow. However, each myoblast clone (n = 2,119) derived from muscle tissues at six stages of human development (weeks 7, 9, 16, and 22 of gestation, 2 mo after birth and adult) expressed slow MyHC upon differentiation. We conclude from these results that the control of slow MyHC expression in vivo during muscle fiber formation in embryonic development is largely extrinsic to the myoblast. By contrast, human myoblast clones from the same samples differed in their expression of embryonic and neonatal MyHCs, in agreement with studies in other species, and this difference was shown to be stably heritable. Even after 25 population doublings in tissue culture, embryonic stage myoblasts did not give rise to myoblasts capable of expressing MyHCs typical of neonatal stages, indicating that stage-specific differences are not under the control of a division dependent mechanism, or

  17. MrkH, a novel c-di-GMP-dependent transcriptional activator, controls Klebsiella pneumoniae biofilm formation by regulating type 3 fimbriae expression.

    Directory of Open Access Journals (Sweden)

    Jonathan J Wilksch

    2011-08-01

    Full Text Available Klebsiella pneumoniae causes significant morbidity and mortality worldwide, particularly amongst hospitalized individuals. The principle mechanism for pathogenesis in hospital environments involves the formation of biofilms, primarily on implanted medical devices. In this study, we constructed a transposon mutant library in a clinical isolate, K. pneumoniae AJ218, to identify the genes and pathways implicated in biofilm formation. Three mutants severely defective in biofilm formation contained insertions within the mrkABCDF genes encoding the main structural subunit and assembly machinery for type 3 fimbriae. Two other mutants carried insertions within the yfiN and mrkJ genes, which encode GGDEF domain- and EAL domain-containing c-di-GMP turnover enzymes, respectively. The remaining two isolates contained insertions that inactivated the mrkH and mrkI genes, which encode for novel proteins with a c-di-GMP-binding PilZ domain and a LuxR-type transcriptional regulator, respectively. Biochemical and functional assays indicated that the effects of these factors on biofilm formation accompany concomitant changes in type 3 fimbriae expression. We mapped the transcriptional start site of mrkA, demonstrated that MrkH directly activates transcription of the mrkA promoter and showed that MrkH binds strongly to the mrkA regulatory region only in the presence of c-di-GMP. Furthermore, a point mutation in the putative c-di-GMP-binding domain of MrkH completely abolished its function as a transcriptional activator. In vivo analysis of the yfiN and mrkJ genes strongly indicated their c-di-GMP-specific function as diguanylate cyclase and phosphodiesterase, respectively. In addition, in vitro assays showed that purified MrkJ protein has strong c-di-GMP phosphodiesterase activity. These results demonstrate for the first time that c-di-GMP can function as an effector to stimulate the activity of a transcriptional activator, and explain how type 3 fimbriae

  18. A novel function of RING finger protein 10 in transcriptional regulation of the myelin-associated glycoprotein gene and myelin formation in Schwann cells.

    Directory of Open Access Journals (Sweden)

    Shinya Hoshikawa

    Full Text Available Myelin-associated glycoprotein (MAG has been detected in Schwann cells prior to the onset of myelination, suggesting its functions in the initiation of myelination. However, transcriptional regulatory mechanisms of MAG remain to be elucidated. Here, we analyzed the promoter of the MAG gene by using luciferase reporter systems in the primary rat Schwann cells. We identified a novel cis-acting element located 160 bp upstream from the MAG transcription initiation site. Using the identified cis-element as a bait, we performed yeast one-hybrid screening and isolated a cDNA encoding a RNF10 as a putative trans-acting protein. When overexpressed in Schwann cells, RNF10 enhanced the activity of the MAG promoter. When RNF10 expression in Schwann cells was knocked down by siRNA, endogenous MAG mRNA and protein expression decreased. Furthermore, we evaluated myelin synthesis using Schwann cell-DRG neuron cocultures. When Schwann cells were infected with retrovirus expressing RNF10 siRNA, myelin formation was inhibited. These data suggest that RNF10 regulates MAG expression and is required for myelin formation.

  19. GGPPS-mediated Rab27A geranylgeranylation regulates β cell dysfunction during type 2 diabetes development by affecting insulin granule docked pool formation.

    Science.gov (United States)

    Jiang, Shan; Shen, Di; Jia, Wen-Jun; Han, Xiao; Shen, Ning; Tao, Weiwei; Gao, Xiang; Xue, Bin; Li, Chao-Jun

    2016-01-01

    Loss of first-phase insulin secretion associated with β cell dysfunction is an independent predictor of type 2 diabetes mellitus (T2DM) onset. Here we found that a critical enzyme involved in protein prenylation, geranylgeranyl pyrophosphate synthase (GGPPS), is required to maintain first-phase insulin secretion. GGPPS shows a biphasic expression pattern in islets of db/db mice during the progression of T2DM: GGPPS is increased during the insulin compensatory period, followed by a decrease during β cell dysfunction. Ggpps deletion in β cells results in typical T2DM β cell dysfunction, with blunted glucose-stimulated insulin secretion and consequent insulin secretion insufficiency. However, the number and size of islets and insulin biosynthesis are unaltered. Transmission electron microscopy shows a reduced number of insulin granules adjacent to the cellular membrane, suggesting a defect in docked granule pool formation, while the reserve pool is unaffected. Ggpps ablation depletes GGPP and impairs Rab27A geranylgeranylation, which is responsible for the docked pool deficiency in Ggpps-null mice. Moreover, GGPPS re-expression or GGPP administration restore glucose-stimulated insulin secretion in Ggpps-null islets. These results suggest that GGPPS-controlled protein geranylgeranylation, which regulates formation of the insulin granule docked pool, is critical for β cell function and insulin release during the development of T2DM.

  20. Hibiscus sabdariffa leaf polyphenolic extract inhibits LDL oxidation and foam cell formation involving up-regulation of LXRα/ABCA1 pathway.

    Science.gov (United States)

    Chen, Jing-Hsien; Wang, Chau-Jong; Wang, Chi-Ping; Sheu, Jenn-Yuan; Lin, Chia-Liang; Lin, Hui-Hsuan

    2013-11-01

    The oxidative modification of low-density lipoprotein (LDL) is involved in the pathogenesis of atherosclerotic lesions through the formation of macrophage-derived foam cells. In the present study, we aimed to investigate the anti-atherosclerotic effect of Hibiscus sabdariffa leaf polyphenolic extract (HLP), which is rich in flavonoid. The inhibitory effect of HLP on oxidation and lipid peroxidation of LDL was defined in vitro. HLP showed potential in reducing foam cell formation and intracellular lipid accumulation in oxidised-LDL (ox-LDL)-induced macrophage J774A.1 cells under non-cytotoxic concentrations. Molecular data showed these influences of HLP might be mediated via liver-X receptor α (LXRα)/ATP-binding cassette transporter A1 (ABCA1) pathway, as demonstrated by the transfection of LXRα siRNA. Our data implied that HLP up-regulated the LXRα/ABCA1 pathway, which in turn led to stimulation of cholesterol removal from macrophages and delay atherosclerosis. These results suggested that HLP potentially could be developed as an anti-atherosclerotic agent. PMID:23768373

  1. Non-toxic plant metabolites regulate Staphylococcus viability and biofilm formation: a natural therapeutic strategy useful in the treatment and prevention of skin infections.

    Science.gov (United States)

    Morán, A; Gutiérrez, S; Martínez-Blanco, H; Ferrero, M A; Monteagudo-Mera, A; Rodríguez-Aparicio, L B

    2014-01-01

    In the present study, the efficacy of generally recognised as safe (GRAS) antimicrobial plant metabolites in regulating the growth of Staphylococcus aureus and S. epidermidis was investigated. Thymol, carvacrol and eugenol showed the strongest antibacterial action against these microorganisms, at a subinhibitory concentration (SIC) of ≤ 50 μg ml(-1). Genistein, hydroquinone and resveratrol showed antimicrobial effects but with a wide concentration range (SIC = 50-1,000 μg ml(-1)), while catechin, gallic acid, protocatechuic acid, p-hydroxybenzoic acid and cranberry extract were the most biologically compatible molecules (SIC ≥ 1000 μg ml(-1)). Genistein, protocatechuic acid, cranberry extract, p-hydroxybenzoic acid and resveratrol also showed anti-biofilm activity against S. aureus, but not against S. epidermidis in which, surprisingly, these metabolites stimulated biofilm formation (between 35% and 1,200%). Binary combinations of cranberry extract and resveratrol with genistein, protocatechuic or p-hydroxibenzoic acid enhanced the stimulatory effect on S. epidermidis biofilm formation and maintained or even increased S. aureus anti-biofilm activity. PMID:25397362

  2. Functional Interactions between 17β-Estradiol and Progesterone Regulate Autophagy during Acini Formation by Bovine Mammary Epithelial Cells in 3D Cultures

    Directory of Open Access Journals (Sweden)

    Katarzyna Zielniok

    2014-01-01

    Full Text Available Mammary gland epithelium forms a network of ducts and alveolar units under control of ovarian hormones: 17-beta-estradiol (E2 and progesterone (P4. Mammary epithelial cells (MECs cultured on reconstituted basement membrane (rBM form three-dimensional (3D acini composed of polarized monolayers surrounding a lumen. Using the 3D culture of BME-UV1 bovine MECs we previously demonstrated that autophagy was induced in the centrally located cells of developing spheroids, and sex steroids increased this process. In the present study we showed that E2 and P4 enhanced the expression of ATG3, ATG5, and BECN1 genes during acini formation, and this effect was accelerated in the presence of both hormones together. The stimulatory action of E2 and P4 was also reflected by increased levels of Atg5, Atg3, and LC3-II proteins. Additionally, the activity of kinases involved in autophagy regulation, Akt, ERK, AMPK, and mTOR, was examined. E2 + P4 slightly increased the level of phosphorylated AMPK but diminished phosphorylated Akt and mTOR on day 9 of 3D culture. Thus, the synergistic actions of E2 and P4 accelerate the development of bovine mammary acini, which may be connected with stimulation of ATGs expression, as well as regulation of signaling pathways (PI3K/Akt/mTOR; AMPK/mTOR involved in autophagy induction.

  3. MASSUGU2 encodes Aux/IAA19, an auxin-regulated protein that functions together with the transcriptional activator NPH4/ARF7 to regulate differential growth responses of hypocotyl and formation of lateral roots in Arabidopsis thaliana.

    Science.gov (United States)

    Tatematsu, Kiyoshi; Kumagai, Satoshi; Muto, Hideki; Sato, Atsuko; Watahiki, Masaaki K; Harper, Reneé M; Liscum, Emmanuel; Yamamoto, Kotaro T

    2004-02-01

    We have isolated a dominant, auxin-insensitive mutant of Arabidopsis thaliana, massugu2 (msg2), that displays neither hypocotyl gravitropism nor phototropism, fails to maintain an apical hook as an etiolated seedling, and is defective in lateral root formation. Yet other aspects of growth and development of msg2 plants are almost normal. These characteristics of msg2 are similar to those of another auxin-insensitive mutant, non-phototropic hypocotyl4 (nph4), which is a loss-of-function mutant of AUXIN RESPONSE FACTOR7 (ARF7) (Harper et al., 2000). Map-based cloning of the MSG2 locus reveals that all four mutant alleles result in amino acid substitutions in the conserved domain II of an Auxin/Indole-3-Acetic Acid protein, IAA19. Interestingly, auxin inducibility of MSG2/IAA19 gene expression is reduced by 65% in nph4/arf7. Moreover, MSG2/IAA19 protein binds to the C-terminal domain of NPH4/ARF7 in a Saccharomyces cerevisiae (yeast) two-hybrid assay and to the whole latter protein in vitro by pull-down assay. These results suggest that MSG2/IAA19 and NPH4/ARF7 may constitute a negative feedback loop to regulate differential growth responses of hypocotyls and lateral root formation.

  4. Silencing BMI1 eliminates tumor formation of pediatric glioma CD133+ cells not by affecting known targets but by down-regulating a novel set of core genes.

    Science.gov (United States)

    Baxter, Patricia A; Lin, Qi; Mao, Hua; Kogiso, Mari; Zhao, Xiumei; Liu, Zhigang; Huang, Yulun; Voicu, Horatiu; Gurusiddappa, Sivashankarappa; Su, Jack M; Adesina, Adekunle M; Perlaky, Laszlo; Dauser, Robert C; Leung, Hon-chiu Eastwood; Muraszko, Karin M; Heth, Jason A; Fan, Xing; Lau, Ching C; Man, Tsz-Kwong; Chintagumpala, Murali; Li, Xiao-Nan

    2014-01-01

    Clinical outcome of children with malignant glioma remains dismal. Here, we examined the role of over-expressed BMI1, a regulator of stem cell self-renewal, in sustaining tumor formation in pediatric glioma stem cells. Our investigation revealed BMI1 over-expression in 29 of 54 (53.7%) pediatric gliomas, 8 of 8 (100%) patient derived orthotopic xenograft (PDOX) mouse models, and in both CD133+ and CD133- glioma cells. We demonstrated that lentiviral-shRNA mediated silencing of suppressed cell proliferation in vitro in cells derived from 3 independent PDOX models and eliminated tumor-forming capacity of CD133+ and CD133- cells derived from 2 PDOX models in mouse brains. Gene expression profiling showed that most of the molecular targets of BMI1 ablation in CD133+ cells were different from that in CD133- cells. Importantly, we found that silencing BMI1 in CD133+ cells derived from 3 PDOX models did not affect most of the known genes previously associated with the activated BMI1, but modulated a novel set of core genes, including RPS6KA2, ALDH3A2, FMFB, DTL, API5, EIF4G2, KIF5c, LOC650152, C20ORF121, LOC203547, LOC653308, and LOC642489, to mediate the elimination of tumor formation. In summary, we identified the over-expressed BMI1 as a promising therapeutic target for glioma stem cells, and suggest that the signaling pathways associated with activated BMI1 in promoting tumor growth may be different from those induced by silencing BMI1 in blocking tumor formation. These findings highlighted the importance of careful re-analysis of the affected genes following the inhibition of abnormally activated oncogenic pathways to identify determinants that can potentially predict therapeutic efficacy.

  5. SLE boundary visits

    CERN Document Server

    Jokela, Niko; Kytölä, Kalle

    2013-01-01

    We study the probabilities with which chordal Schramm-Loewner Evolutions (SLE) visit small neighborhoods of boundary points. We find explicit formulas for general chordal SLE boundary visiting probability amplitudes, also known as SLE boundary zig-zags or order refined SLE multi-point Green's functions on the boundary. Remarkably, an exact answer can be found to this important SLE question for an arbitrarily large number of marked points. The main technique employed is a spin chain - Coulomb gas correspondence between tensor product representations of a quantum group and functions given by Dotsenko-Fateev type integrals. We show how to express these integral formulas in terms of regularized real integrals, and we discuss their numerical evaluation. The results are universal in the sense that apart from an overall multiplicative constant the same formula gives the amplitude for many different formulations of the SLE boundary visit problem. The formula also applies to renormalized boundary visit probabilities f...

  6. Optimal boundaries for decisions

    Directory of Open Access Journals (Sweden)

    Carfi', David

    2008-01-01

    Full Text Available In this paper we state and prove some new results on the optimal boundaries. These boundaries (called Pareto boundaries too are of increasing importance in the applications to Decision Theory. First of all the Pareto boundaries are the first and most important generalization of the concept of optimum; on the other hand, if f is a real functional defined on a non empty set X and K is a part of X, the determination of the optimal boundaries of the part K with respect to some preorder of X for which f is strictly increasing permits to reduce the optimization problem (f, K, inf (or (f, K, sup to the problem (f, minP(K, inf (resp. (f, maxP(K, sup, where by minP(K we denoted the minimal boundary of K (that in general is greatly smoller than K.

  7. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2012-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation. Draw...

  8. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2011-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation. Draw...

  9. Investigations of the boundary conditions of acicular ferrite formation in fast-quenched welded materials. Final report; Untersuchungen der Randbedingungen fuer die Bildung von 'acicular ferrite' in Schweissguetern bei schneller Abkuehlung. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Dilthey, U.; Biesenbach, M.

    2000-06-19

    The authors investigated the boundary conditions in which a fine-grained ferritic needle structure with sufficient low-temperature toughness is obtained in conditions of extreme heating and cooling. Alloy compositions and welding boundary conditions were investigated for laser welding, electron beam welding in a vacuum and electron beam welding at atmospheric pressure. [German] Im Rahmen dieser Arbeit soll untersucht werden, welche Randbedingungen erfuellt sein muessen, damit sich unter extremen Aufheiz- und Abkuehlbedingungen, wie sie bei den Strahlschweissverfahren vorliegen, ein feinkoerniges nadelferritisches Gefuege mit ausreichend hoher Tieftemperaturzaehigkeit bildet. Diesbezueglich ist fuer die Strahlschweissverfahren Laserstrahlschweissen, Elektronenstrahlschweissen im Vakuum und Elektronenstrahlschweissen unter Atmosphaerendruck zu ermitteln, welche Legierungszusammensetzungen diese Voraussetzungen erfuellen und wie sie unter realen Schweissbedingungen verwirklicht werden koennen. (orig.)

  10. The homolog of the five SH3-domain protein (HOFI/SH3PXD2B regulates lamellipodia formation and cell spreading.

    Directory of Open Access Journals (Sweden)

    Árpád Lányi

    Full Text Available Motility of normal and transformed cells within and across tissues requires specialized subcellular structures, e.g. membrane ruffles, lamellipodia and podosomes, which are generated by dynamic rearrangements of the actin cytoskeleton. Because the formation of these sub-cellular structures is complex and relatively poorly understood, we evaluated the role of the adapter protein SH3PXD2B [HOFI, fad49, Tks4], which plays a role in the development of the eye, skeleton and adipose tissue. Surprisingly, we find that SH3PXD2B is requisite for the development of EGF-induced membrane ruffles and lamellipodia, as well as for efficient cellular attachment and spreading of HeLa cells. Furthermore, SH3PXD2B is present in a complex with the non-receptor protein tyrosine kinase Src, phosphorylated by Src, which is consistent with SH3PXD2B accumulating in Src-induced podosomes. Furthermore, SH3PXD2B closely follows the subcellular relocalization of cortactin to Src-induced podosomes, EGF-induced membrane ruffles and lamellipodia. Because SH3PXD2B also forms a complex with the C-terminal region of cortactin, we propose that SH3PXD2B is a scaffold protein that plays a key role in regulating the actin cytoskeleton via Src and cortactin.

  11. Effect of Plant Growth Regulators on a Shoot and Root Formation from the Leaf and Flower Culture of a Standard-type Chrysanthemum 'Jinba'

    International Nuclear Information System (INIS)

    In this study we investigated the conditions of a higher frequency for regenerated plants from different explants of a standard-type chrysanthemum 'Jinba'. In vitro culture was initiated on an MS medium containing 3% sucrose, 0.8% agar, and 5 μM benzyl adenine (BA) with naphthalene acetic acid (NAA) by using surface-sterilized leaf and flower tissues from greenhouse-grown plants. Direct shoot regeneration from the leaf and flower explants was obtained 21 to 28 days after the initial culture. Among the seven combinations of the growth regulators used for the culture, the most efficient condition for the shoot and root formation from the leaf tissue was obtained when the MS basic medium was supplemented with 0.5 mg L-¹ BA and 1.0 mg L-¹ NAA, and 0.1 mg L-¹ BA and 0.5 mg L-¹ NAA, while the culture using floret tissues was most efficient on the medium supplemented with 0.5 mg L-¹ BA and 0.5 mg L-¹ NAA, and 0.1 mg L-¹ BA and 1.0 mg L-¹ NAA. These results will provide valuable information to help set up an efficient system for a tissue culture of chrysanthemum cv. Jinba to improve one or some of its negative traits in combination with a radiation mutagenesis approach

  12. Intercellular Adhesion-Dependent Cell Survival and ROCK-Regulated Actomyosin-Driven Forces Mediate Self-Formation of a Retinal Organoid

    Directory of Open Access Journals (Sweden)

    Albert Lowe

    2016-05-01

    Full Text Available In this study we dissected retinal organoid morphogenesis in human embryonic stem cell (hESC-derived cultures and established a convenient method for isolating large quantities of retinal organoids for modeling human retinal development and disease. Epithelialized cysts were generated via floating culture of clumps of Matrigel/hESCs. Upon spontaneous attachment and spreading of the cysts, patterned retinal monolayers with tight junctions formed. Dispase-mediated detachment of the monolayers and subsequent floating culture led to self-formation of retinal organoids comprising patterned neuroretina, ciliary margin, and retinal pigment epithelium. Intercellular adhesion-dependent cell survival and ROCK-regulated actomyosin-driven forces are required for the self-organization. Our data supports a hypothesis that newly specified neuroretina progenitors form characteristic structures in equilibrium through minimization of cell surface tension. In long-term culture, the retinal organoids autonomously generated stratified retinal tissues, including photoreceptors with ultrastructure of outer segments. Our system requires minimal manual manipulation, has been validated in two lines of human pluripotent stem cells, and provides insight into optic cup invagination in vivo.

  13. Systems biology of lignin biosynthesis in Populus trichocarpa: heteromeric 4-coumaric acid:coenzyme A ligase protein complex formation, regulation, and numerical modeling.

    Science.gov (United States)

    Chen, Hsi-Chuan; Song, Jina; Wang, Jack P; Lin, Ying-Chung; Ducoste, Joel; Shuford, Christopher M; Liu, Jie; Li, Quanzi; Shi, Rui; Nepomuceno, Angelito; Isik, Fikret; Muddiman, David C; Williams, Cranos; Sederoff, Ronald R; Chiang, Vincent L

    2014-03-01

    As a step toward predictive modeling of flux through the pathway of monolignol biosynthesis in stem differentiating xylem of Populus trichocarpa, we discovered that the two 4-coumaric acid:CoA ligase (4CL) isoforms, 4CL3 and 4CL5, interact in vivo and in vitro to form a heterotetrameric protein complex. This conclusion is based on laser microdissection, coimmunoprecipitation, chemical cross-linking, bimolecular fluorescence complementation, and mass spectrometry. The tetramer is composed of three subunits of 4CL3 and one of 4CL5. 4CL5 appears to have a regulatory role. This protein-protein interaction affects the direction and rate of metabolic flux for monolignol biosynthesis in P. trichocarpa. A mathematical model was developed for the behavior of 4CL3 and 4CL5 individually and in mixtures that form the enzyme complex. The model incorporates effects of mixtures of multiple hydroxycinnamic acid substrates, competitive inhibition, uncompetitive inhibition, and self-inhibition, along with characteristic of the substrates, the enzyme isoforms, and the tetrameric complex. Kinetic analysis of different ratios of the enzyme isoforms shows both inhibition and activation components, which are explained by the mathematical model and provide insight into the regulation of metabolic flux for monolignol biosynthesis by protein complex formation.

  14. Apoptotic wing degeneration and formation of an altruism-regulating glandular appendage (gemma) in the ponerine ant Diacamma sp. from Japan (Hymenoptera, Formicidae, Ponerinae).

    Science.gov (United States)

    Gotoh, A; Sameshima, S; Tsuji, K; Matsumoto, T; Miura, T

    2005-02-01

    We here show an example of morphological novelties, which have evolved from insect wings into the specific structures controlling social behaviour in an ant species. Most ant colonies consist of winged queen(s) and wingless workers. In the queenless ponerine ant Diacamma sp. from Japan, however, all female workers have a pair of small thoracic appendages, called "gemmae", which are homologous to the forewings and acts as an organ regulating altruism expression. Most workers, whose gemmae are clipped off by other colony members, become nonreproductive helpers, while only a single individual with complete gemmae becomes functionally reproductive. We examined histologically the development of gemmae, and compared it with that of functional wings in males. Female larvae had well-developed wing discs for both fore- and hindwings. At pupation, however, the wing discs started to evaginate and later degenerate. The hindwing discs completely degenerated, while the degeneration of forewing discs was incomplete, leading to the formation of gemmae. The degeneration process involved apoptotic cell death as confirmed by TUNEL assay. In addition, glandular cells differentiated from the epithelial cells of the forewing buds after completion of pupation. The mechanism of developmental transition from wing to gemma can be regarded as an evolutionary gain of new function, which can be seen in insect appendages and vertebrate limbs. PMID:15647944

  15. THEORY AND METHOD FOR WETLAND BOUNDARY DELINEATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the analysis of the subjectivity of wetland boundary criteria and their causes at present, this paper suggested that, under the condition that the mechanism of wetland formation process has not been understood,"black box" method of System Theory can be used to delineate wetland boundaries scientifically. After analyzing the difference of system construction among aquatic habitats, wetlands and uplands, the lower limit of rooted plants was chosen as the lower boundary criterion of wetlands. Because soil diagnostic horizon is the result of the long-term interaction among all environments, and it is less responsive than vegetation to short-term change, soil diagnostic horizon was chosen as the indicator to delineate wetland upper boundary, which lies at the thinning-out point of soil diagnostic horizon. Case study indicated that it was feasible using the lower limit of rooted plants and the thinning-out point of soil diagnostic horizon as criteria to delineate the lower and upper boundaries of wetland. In the study area, the thinning-out line of albic horizon was coincident with the 55.74m contour line, the maximum horizonerror was less than lm, and the maximum vertical error less than 0.04m. The problem on wetland definition always arises on the boundaries. Having delineated wetland boundaries, wetlands can be defined as follows: wetlands are the transitional zones between uplands and deepwater habitats, they are a kind of azonal complex that are inundated or saturated by surface or ground water, with the lower boundary lying at the lower limit of rooted plants, and the upper boundary at the thinning-out line of upland soil diagnostic horizon.

  16. Flow stress anisotropy caused by geometrically necessary boundaries

    DEFF Research Database (Denmark)

    Hansen, N.; Juul Jensen, D.

    1992-01-01

    The microstructural anisotropy of deformed metal is related to the formation of geometrically necessary boundaries such as dense dislocation walls and microbands. These boundaries have a macroscopic orientation with respect to the sample axes and they can resist slip due to a high concentration of...

  17. HUC 8 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  18. FWS Approved Acquisition Boundaries

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This data layer depicts the external boundaries of lands and waters that are approved for acquisition by the U.S. Fish and Wildlife Service (USFWS) in North...

  19. Allegheny County Parcel Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains parcel boundaries attributed with county block and lot number. If viewing this description on the Western Pennsylvania Regional Data Center’s...

  20. Allegheny County Boundary

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains the Allegheny County boundary. If viewing this description on the Western Pennsylvania Regional Data Center’s open data portal...

  1. Tax Unit Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — The Statewide GIS Tax Unit boundary file was created through a collaborative partnership between the State of Kansas Department of Revenue Property Valuation...

  2. Haleakala National Park Boundary

    Data.gov (United States)

    National Park Service, Department of the Interior — The park boundary of Haleakala National Park was digitized from USGS quadrangle maps. Haleakala National Park was established in September 1960. Recent NPS land...

  3. BoundaryOther_SUNIONS

    Data.gov (United States)

    Vermont Center for Geographic Information — BoundaryOther_SUNIONS was intended to provide outlines of all Vermont school supervisory unions for use in displaying demographic data pertinent to each union, and...

  4. Allegheny County Parcel Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains parcel boundaries attributed with county block and lot number. Use the Property Information Extractor for more control downloading a filtered...

  5. State Park Statutory Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Legislative statutory boundaries for sixty six state parks, six state recreation areas, and eight state waysides. These data are derived principally from DNR's...

  6. NM School District Boundaries

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The dataset represents the boundaries of all public school districts in the state of New Mexico. The source for the data layer is the New Mexico Public Education...

  7. National Forest Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This theme shows the USFS national forest boundaries in the state. This data was acquired from the GIS coordinators at both the Chippewa National Forest and the...

  8. Minnesota County Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography...

  9. Watershed Boundary Areas

    Data.gov (United States)

    Department of Homeland Security — This map layer contains hydrologic unit boundaries and codes for the United States, Puerto Rico, and the U.S. Virgin Islands. It was revised for inclusion in the...

  10. Minnesota County Boundaries - lines

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography...

  11. Shoot Branching and Leaf Dissection in Tomato Are Regulated by Homologous Gene Modules[W

    Science.gov (United States)

    Busch, Bernhard L.; Schmitz, Gregor; Rossmann, Susanne; Piron, Florence; Ding, Jia; Bendahmane, Abdelhafid; Theres, Klaus

    2011-01-01

    Aerial plant architecture is predominantly determined by shoot branching and leaf morphology, which are governed by apparently unrelated developmental processes, axillary meristem formation, and leaf dissection. Here, we show that in tomato (Solanum lycopersicum), these processes share essential functions in boundary establishment. Potato leaf (C), a key regulator of leaf dissection, was identified to be the closest paralog of the shoot branching regulator Blind (Bl). Comparative genomics revealed that these two R2R3 MYB genes are orthologs of the Arabidopsis thaliana branching regulator REGULATOR OF AXILLARY MERISTEMS1 (RAX1). Expression studies and complementation analyses indicate that these genes have undergone sub- or neofunctionalization due to promoter differentiation. C acts in a pathway independent of other identified leaf dissection regulators. Furthermore, the known leaf complexity regulator Goblet (Gob) is crucial for axillary meristem initiation and acts in parallel to C and Bl. Finally, RNA in situ hybridization revealed that the branching regulator Lateral suppressor (Ls) is also expressed in leaves. All four boundary genes, C, Bl, Gob, and Ls, may act by suppressing growth, as indicated by gain-of-function plants. Thus, leaf architecture and shoot architecture rely on a conserved mechanism of boundary formation preceding the initiation of leaflets and axillary meristems. PMID:22039213

  12. Planetary boundaries: guiding human development on a changing planet

    NARCIS (Netherlands)

    Steffen, W.; Richardson, K.; Rockström, J.; Cornell, S.E.; Fetzer, I.; Bennett, E.; Biggs, R.; Vries, de W.

    2015-01-01

    The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth System. Here, we revise and update the planetary boundaries framework, with a focus on the underpinning biophysical science, based on t

  13. Shifting Institutional Boundaries through Cross-Border Higher Education

    Science.gov (United States)

    Amaral, Alberto; Tavares, Orlanda; Cardoso, Sónia; Sin, Cristina

    2016-01-01

    Cross-border higher education (CBHE) has been changing the organizational boundaries of higher education institutions (HEIs). This study aims to analyze the shifting boundaries of Portuguese HEIs through the lens of the identity concept in organization theories, considering three contexts with different levels of regulation: African…

  14. An integrated molecular landscape implicates the regulation of dendritic spine formation through insulin-related signalling in obsessive–compulsive disorder

    Science.gov (United States)

    van de Vondervoort, Ilse; Poelmans, Geert; Aschrafi, Armaz; Pauls, David L.; Buitelaar, Jan K.; Glennon, Jeffrey C.; Franke, Barbara

    2016-01-01

    Background Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder with onset in childhood and is characterized by obsessions (recurrent, intrusive, persistent thoughts, impulses and/or ideas that often cause anxiety or distress) and compulsions (ritualized and stereotypic behaviours or mental acts that are often performed to relieve anxiety or distress associated with obsessions). Although OCD is a heritable disorder, its complex molecular etiology is poorly understood. Methods We combined enrichment analyses and an elaborate literature review of the top-ranked genes emerging from the 2 published genome-wide association studies of OCD and candidate genes implicated through other evidence in order to identify biological processes that, when dysregulated, increase the risk for OCD. Results The resulting molecular protein landscape was enriched for proteins involved in regulating postsynaptic dendritic spine formation — and hence synaptic plasticity — through insulin-dependent molecular signalling cascades. Limitations This study is a first attempt to integrate molecuar information from different sources in order to identify biological mechanisms underlying OCD etiology. Our findings are constrained by the limited information from hypothesis-free studies and the incompleteness and existing limitations of the OCD literature and the gene function annotations of gene enrichment tools. As this study was solely based on in silico analyses, experimental validation of the provided hypotheses is warranted. Conclusion Our work suggests a key role for insulin and insulin-related signalling in OCD etiology and — if confirmed by independent studies — could eventually pave the way for the development of novel OCD treatments. PMID:26854754

  15. The first magnetostratigraphic data on the stratotype of the Lopata Formation, Northeastern Yenisei Ridge: Problems of its age and paleogeography of the Siberian Platform at the Proterozoic-Phanerozoic boundary

    Science.gov (United States)

    Shatsillo, A. V.; Kuznetsov, N. B.; Pavlov, V. E.; Fedonkin, M. A.; Priyatkina, N. S.; Serov, S. G.; Rudko, S. V.

    2015-12-01

    New paleomagnetic and magnetostratigraphic data are presented for the stratotype of the Upper Riphean Lopata Formation (Teya River, Yenisei Ridge). The paleomagnetic pole calculated is significantly distinct from the Phanerozoic and Riphean poles of the Siberian Platform and is similar to the Late Vendian-Early Cambrian poles of the Madagascar Group. The stratigraphic range studied is characterized by an anomalously high frequency of geomagnetic inversions (15 zones of magnetic polarity), which is comparable with the inversion frequency of the Late Vendian sections of Baltica. These data, along with previous paleontological findings, indicate an age of the Lopata Formation of 555-540 Ma.

  16. Boundary breaking for interdisciplinary learning

    Directory of Open Access Journals (Sweden)

    Adi Kidron

    2015-10-01

    Full Text Available The purpose of this work is to contribute to the body of knowledge on processesby which students develop interdisciplinary understanding of contents, as well as to suggest technology-enhanced means for supporting them in these processes in the context of higher education. In doing so, we suggest a rethinking of three traditional practices that tend to characterise typical higher education instruction: (1 compartmentalisation of disciplines; (2 traditional pedagogy; and (3 traditional hierarchies based on levels of expertise. Our high-level conjecture was that meaningful dialogue with peers and experts supports both the deepening of ideas in one knowledge domain and the formation of connections between ideas from several domains, both of which are required for the development of interdisciplinary understanding. We developed the Boundary Breaking for Interdisciplinary Learning (BBIL model, which harnesses technology to break boundaries between disciplines, learners and organisational levels of hierarchy. Findings indicate that 36 undergraduate students who participated in an interdisciplinary online course that implemented the BBIL model have significantly improved their interdisciplinary understanding of the course contents. This study illustrates how innovative use of available, free and low-cost technology can produce a ‘positive disruption’ in higher education instruction.

  17. Outer Magnetospheric Boundaries Cluster Results

    CERN Document Server

    Paschmann, Goetz; Schwartz, S J

    2006-01-01

    When the stream of plasma emitted from the Sun (the solar wind) encounters Earth's magnetic field, it slows down and flows around it, leaving behind a cavity, the magnetosphere. The magnetopause is the surface that separates the solar wind on the outside from the Earth's magnetic field on the inside. Because the solar wind moves at supersonic speed, a bow shock must form ahead of the magnetopause that acts to slow the solar wind to subsonic speeds. Magnetopause, bow shock and their environs are rich in exciting processes in collisionless plasmas, such as shock formation, magnetic reconnection, particle acceleration and wave-particle interactions. They are interesting in their own right, as part of Earth's environment, but also because they are prototypes of similar structures and phenomena that are ubiquitous in the universe, having the unique advantage that they are accessible to in situ measurements. The boundaries of the magnetosphere have been the target of direct in-situ measurements since the beginning ...

  18. Computation of Boundary Layers

    Directory of Open Access Journals (Sweden)

    József Dénes

    2004-11-01

    Full Text Available This paper is the first part of a series of studies where we examine several methods for the solution of the boundary layer equation of the fluid mechanics. The first of these is the analytical or rather quasi analytical method due to Blasius. This method reduces a system of partial differential equations to a system of ordinary differential equations and these in turn are solved by numerical methods since no exact solution of the Blasius type equations is known. We determind all the Blasius equation neccessary for up to 11-th order approximation. Our further aim to study the finite difference numerical solutions of the boundary layer equation and some of the methods applying weighted residual principles and by comparing these with the ”exact” solutions arrived at by Blasius method develop a quick reliable method for solving the boundary layer equation.

  19. Free-boundary equilibria

    International Nuclear Information System (INIS)

    A self-contained MHD description of the Helias class stellarators is obtained by determining appropriate external currents (coils) producing the Helias vacuum field and by the subsequent computing of the free-boundary equilibrium. Coil configurations are calculated with the NESCOIL code, the free-boundary equilibrium is studied via the NEMEC code, which combines the 3D fixed-boundary VMEC code and the NESTOR code for determining the vacuum field surrounding the plasma. Results for the 5081 Helias configuration, being considered for the W VII-X device are shown. The 5081 is a five-period device with aspect ratio 10 and a rotational transform between 0.8 and 1.0. It is MHD stable up to a beta value of 0.05

  20. Adaptive Sentence Boundary Disambiguation

    CERN Document Server

    Palmer, D D; Palmer, David D.; Hearst, Marti A.

    1994-01-01

    Labeling of sentence boundaries is a necessary prerequisite for many natural language processing tasks, including part-of-speech tagging and sentence alignment. End-of-sentence punctuation marks are ambiguous; to disambiguate them most systems use brittle, special-purpose regular expression grammars and exception rules. As an alternative, we have developed an efficient, trainable algorithm that uses a lexicon with part-of-speech probabilities and a feed-forward neural network. After training for less than one minute, the method correctly labels over 98.5\\% of sentence boundaries in a corpus of over 27,000 sentence-boundary marks. We show the method to be efficient and easily adaptable to different text genres, including single-case texts.

  1. Spectrum of local boundary operators from boundary form factor bootstrap

    OpenAIRE

    Szots, M.; Takacs, G.

    2007-01-01

    Using the recently introduced boundary form factor bootstrap equations, we map the complete space of their solutions for the boundary version of the scaling Lee-Yang model and sinh-Gordon theory. We show that the complete space of solutions, graded by the ultraviolet behaviour of the form factors can be brought into correspondence with the spectrum of local boundary operators expected from boundary conformal field theory, which is a major evidence for the correctness of the boundary form fact...

  2. Spectrum of local boundary operators from boundary form factor bootstrap

    CERN Document Server

    Szots, M

    2007-01-01

    Using the recently introduced boundary form factor bootstrap equations, we map the complete space of their solutions for the boundary version of the scaling Lee-Yang model and sinh-Gordon theory. We show that the complete space of solutions, graded by the ultraviolet behaviour of the form factors can be brought into correspondence with the spectrum of local boundary operators expected from boundary conformal field theory, which is a major evidence for the correctness of the boundary form factor bootstrap framework.

  3. Boundary Logarithmic Conformal Field Theory

    CERN Document Server

    Kogan, I I; Kogan, Ian I.; Wheater, John F.

    2000-01-01

    We discuss the effect of boundaries in boundary logarithmic conformal field theory and show, with reference to both $c=-2$ and $c=0$ models, how they produce new features even in bulk correlation functions which are not present in the corresponding models without boundaries. We show how Cardy's relation between boundary states and bulk quantities is modified.

  4. Formation of chromosomal domains in interphase by loop extrusion

    Science.gov (United States)

    Fudenberg, Geoffrey

    While genomes are often considered as one-dimensional sequences, interphase chromosomes are organized in three dimensions with an essential role for regulating gene expression. Recent studies have shown that Topologically Associating Domains (TADs) are fundamental structural and functional building blocks of human interphase chromosomes. Despite observations that architectural proteins, including CTCF, demarcate and maintain the borders of TADs, the mechanisms underlying TAD formation remain unknown. Here we propose that loop extrusion underlies the formation TADs. In this process, cis-acting loop-extruding factors, likely cohesins, form progressively larger loops, but stall at TAD boundaries due to interactions with boundary proteins, including CTCF. This process dynamically forms loops of various sizes within but not between TADs. Using polymer simulations, we find that loop extrusion can produce TADs as determined by our analyses of the highest-resolution experimental data. Moreover, we find that loop extrusion can explain many diverse experimental observations, including: the preferential orientation of CTCF motifs and enrichments of architectural proteins at TAD boundaries; TAD boundary deletion experiments; and experiments with knockdown or depletion of CTCF, cohesin, and cohesin-loading factors. Together, the emerging picture from our work is that TADs are formed by rapidly associating, growing, and dissociating loops, presenting a clear framework for understanding interphase chromosomal organization.

  5. Boundaries of the universe

    CERN Document Server

    Glasby, John S

    2013-01-01

    The boundaries of space exploration are being pushed back constantly, but the realm of the partially understood and the totally unknown is as great as ever. Among other things this book deals with astronomical instruments and their application, recent discoveries in the solar system, stellar evolution, the exploding starts, the galaxies, quasars, pulsars, the possibilities of extraterrestrial life and relativity.

  6. Challenging the Boundaries

    DEFF Research Database (Denmark)

    Nørgaard, Nina

    2004-01-01

    To many people, challenging the boundaries between the traditional disciplines in foreign language studies means doing cultural studies. The aim of this article is to pull in a different direction by suggesting how the interface between linguistics and literature may be another fertile field to e...

  7. Campylobacter jejuni CsrA complements an Escherichia coli csrA mutation for the regulation of biofilm formation, motility and cellular morphology but not glycogen accumulation

    OpenAIRE

    Fields Joshua A; Thompson Stuart A

    2012-01-01

    Abstract Background Although Campylobacter jejuni is consistently ranked as one of the leading causes of bacterial diarrhea worldwide, the mechanisms by which C. jejuni causes disease and how they are regulated have yet to be clearly defined. The global regulator, CsrA, has been well characterized in several bacterial genera and is known to regulate a number of independent pathways via a post transcriptional mechanism, but remains relatively uncharacterized in the genus Campylobacter. Previou...

  8. Boundary Layer Cloudiness Parameterizations Using ARM Observations

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Albrecht

    2004-09-15

    This study used DOE ARM data and facilities to: (1) study macroscopic properties of continental stratus clouds at SGP and the factors controlling these properties, (2) develop a scientific basis for understanding the processes responsible for the formation of boundary layer clouds using ARM observations in conjunction with simple parametric models and LES, and (3) evaluate cumulus cloud characteristics retrieved from the MMCR operating at TWP-Nauru. In addition we have used high resolution 94 GHz observations of boundary layer clouds and precipitation to: (1) develop techniques for using high temporal resolution Doppler velocities to study large-eddy circulations and turbulence in boundary layer clouds and estimate the limitations of using current and past MMCR data for boundary layer cloud studies, (2) evaluate the capability and limitations of the current MMCR data for estimating reflectivity, vertical velocities, and spectral under low- signal-to-noise conditions associated with weak no n-precipitating clouds, (3) develop possible sampling modes for the new MMCR processors to allow for adequate sampling of boundary layer clouds, and (4) retrieve updraft and downdraft structures under precipitating conditions.

  9. On the Ekman instability at the core-mantle boundary

    Science.gov (United States)

    Chkhetiani, O. G.; Shalimov, S. L.

    2016-05-01

    It is shown that the instability of turbulent flows with Ekman velocity profiles in the vicinity of the core-mantle boundary leads to the formation of horizontally oriented circulating roll structures. The geophysical implications of the presence of such structures in the liquid core are explored, namely, the formation of the hot zones with enhanced conductivity and their influence on geomagnetic reversals.

  10. Light inhibits gravity-regulated peg formation and asymmetric mRNA accumulation of auxin-inducible CsIAA1 in the cortex of the transition zone in cucumber seedlings

    Science.gov (United States)

    Fujii, Nobuharu; Saito, Yuko; Miyazawa, Yutaka; Takahashi, Hideyuki

    When cucumber seedlings are grown horizontally, a specialized protuberance, termed the peg, develops on the lower side of the transition zone between the hypocotyl and the root. Gravimorphogenesis regulates the lateral positioning of the peg in the transition zone and it has been suggested that auxin plays an important role in peg formation in cucumber seedlings. Here, we found that light inhibited auxin-regulated peg formation. In the transition zone of horizontally positioned cucumber seedlings grown in the dark, we detected an asymmetric accumulation of mRNA from the auxin-inducible gene CsIAA1 in the epidermis and cortex. However, in seedlings grown under illumination, this asymmetry was greatly reduced. In dark- and light-grown seedlings, application of 10 -3 M indole-3-acetic acid induced peg formation on both the lower and upper sides of the transition zone. These results suggest that light inhibits peg formation via modification of auxin distribution and/or levels in the transition zone of cucumber seedlings.

  11. Probing grain boundary sink strength at the nanoscale: Energetics and length scales of vacancy and interstitial absorption by grain boundaries in α-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Tschopp, Mark A.; Solanki, K. N.; Gao, Fei; Sun, Xin; Khaleel, Mohammad A.; Horstemeyer, Mark

    2012-02-10

    The energetics and length scales associated with the interaction between point defects (vacancies and self-interstitial atoms) and grain boundaries in bcc Fe was explored. Molecular statics simulations were used to generate a grain boundary structure database that contained {approx}170 grain boundaries with varying tilt and twist character. Then, vacancy and self-interstitial atom formation energies were calculated at all potential grain boundary sites within 15 {angstrom} of the boundary. The present results provide detailed information about the interaction energies of vacancies and self-interstitial atoms with symmetric tilt grain boundaries in iron and the length scales involved with absorption of these point defects by grain boundaries. Both low- and high-angle grain boundaries were effective sinks for point defects, with a few low-{Sigma} grain boundaries (e.g., the {Sigma}3{l_brace}112{r_brace} twin boundary) that have properties different from the rest. The formation energies depend on both the local atomic structure and the distance from the boundary center. Additionally, the effect of grain boundary energy, disorientation angle, and {Sigma} designation on the boundary sink strength was explored; the strongest correlation occurred between the grain boundary energy and the mean point defect formation energies. Based on point defect binding energies, interstitials have {approx}80% more grain boundary sites per area and {approx}300% greater site strength than vacancies. Last, the absorption length scale of point defects by grain boundaries is over a full lattice unit larger for interstitials than for vacancies (mean of 6-7 {angstrom} versus 10-11 {angstrom} for vacancies and interstitials, respectively).

  12. Probing grain boundary sink strength at the nanoscale: Energetics and length scales of vacancy and interstitial absorption by grain boundaries in α-Fe

    Science.gov (United States)

    Tschopp, M. A.; Solanki, K. N.; Gao, F.; Sun, X.; Khaleel, M. A.; Horstemeyer, M. F.

    2012-02-01

    The energetics and length scales associated with the interaction between point defects (vacancies and self-interstitial atoms) and grain boundaries in bcc Fe was explored. Molecular statics simulations were used to generate a grain boundary structure database that contained ≈170 grain boundaries with varying tilt and twist character. Then, vacancy and self-interstitial atom formation energies were calculated at all potential grain boundary sites within 15 Å of the boundary. The present results provide detailed information about the interaction energies of vacancies and self-interstitial atoms with symmetric tilt grain boundaries in iron and the length scales involved with absorption of these point defects by grain boundaries. Both low- and high-angle grain boundaries were effective sinks for point defects, with a few low-Σ grain boundaries (e.g., the Σ3{112} twin boundary) that have properties different from the rest. The formation energies depend on both the local atomic structure and the distance from the boundary center. Additionally, the effect of grain boundary energy, disorientation angle, and Σ designation on the boundary sink strength was explored; the strongest correlation occurred between the grain boundary energy and the mean point defect formation energies. Based on point defect binding energies, interstitials have ≈80% more grain boundary sites per area and ≈300% greater site strength than vacancies. Last, the absorption length scale of point defects by grain boundaries is over a full lattice unit larger for interstitials than for vacancies (mean of 6-7 Å versus 10-11 Å for vacancies and interstitials, respectively).

  13. Boundary conditions of methamphetamine craving.

    Science.gov (United States)

    Lopez, Richard B; Onyemekwu, Chukwudi; Hart, Carl L; Ochsner, Kevin N; Kober, Hedy

    2015-12-01

    Methamphetamine use has increased significantly and become a global health concern. Craving is known to predict methamphetamine use and relapse following abstinence. Some have suggested that cravings are automatic, generalized, and uncontrollable, but experimental work addressing these claims is lacking. In 2 exploratory studies, we tested the boundary conditions of methamphetamine craving by asking: (a) is craving specific to users' preferred route of administration?, and (b) can craving be regulated by cognitive strategies? Two groups of methamphetamine users were recruited. In Study 1, participants were grouped by their preferred route of administration (intranasal vs. smoking), and rated their craving in response to photographs and movies depicting methamphetamine use (via the intranasal vs. smoking route). In Study 2, methamphetamine smokers implemented cognitive regulation strategies while viewing photographs depicting methamphetamine smoking. Strategies involved either focusing on the positive aspects of smoking methamphetamine or the negative consequences of doing so-the latter strategy based on treatment protocols for addiction. In Study 1, we found a significant interaction between group and route of administration, such that participants who preferred to smoke methamphetamine reported significantly stronger craving for smoking stimuli, whereas those who preferred the intranasal route reported stronger craving for intranasal stimuli. In Study 2, participants reported significantly lower craving when focusing on the negative consequences associated with methamphetamine use. Taken together, these findings suggest that strength of craving for methamphetamine is moderated by users' route of administration and can be reduced by cognitive strategies. This has important theoretical, methodological, and clinical implications.

  14. 15 CFR Appendix A to Subpart L of... - Flower Garden Banks National Marine Sanctuary Boundary Coordinates

    Science.gov (United States)

    2010-01-01

    ... Sanctuary Boundary Coordinates A Appendix A to Subpart L of Part 922 Commerce and Foreign Trade Regulations... 922—Flower Garden Banks National Marine Sanctuary Boundary Coordinates This appendix contains a second set of boundary coordinates using the geographic positions of the North American Datum of 1983 (NAD...

  15. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  16. Quantum gravitational effects on boundary

    CERN Document Server

    Park, I Y

    2016-01-01

    Quantum gravitational effects may hold the key to some of the outstanding problems in theoretical physics. In this work we analyze the perturbative quantum effects on the boundary of a gravitational system and Dirichlet boundary condtion imposed at the classical level. Our analysis reveals that for a black hole solution there exists a clash between the quantum effects and Dirichlet boundary condition: the solution of the one-particle-irreducible (1PI) action no longer obeys the Dirichlet boundary condition. The analysis also suggests that the violation of the Dirichlet boundary condition should be tied with a certain mechanism of information storage on the boundary.

  17. Collaboration in Healthcare Through Boundary Work and Boundary Objects

    DEFF Research Database (Denmark)

    Meier, Ninna

    2015-01-01

    . In highly specialized, knowledge-intensive organizations such as healthcare organizations, organizational, professional, and disciplinary boundaries mark the formal structure and division of work. Collaboration and coordination across these boundaries are essential to minimizing gaps in patient care...

  18. Shared care and boundaries:

    DEFF Research Database (Denmark)

    Winthereik, Brit Ross

    2008-01-01

    of responsibilities entailed in shared care projects. Rather than seeking to connect all actors in an unbounded space, shared care might instead suggest a space for patients and professionals to experiment with new roles and responsibilities. Practical implications – When designing coordination tools for health care......Purpose – The paper seeks to examine how an online maternity record involving pregnant women worked as a means to create shared maternity care. Design/methodology/approach – Ethnographic techniques have been used. The paper adopts a theoretical/methodological framework based on science...... and technology studies. Findings – The paper shows how a version of “the responsible patient” emerges from the project which is different from the version envisioned by the project organisation. The emerging one is concerned with the boundary between primary and secondary sector care, and not with the boundary...

  19. Reactor pressure boundary materials

    International Nuclear Information System (INIS)

    With a long-term operation of nuclear power plants, the component materials are degraded under severe reactor conditions such as neutron irradiation, high temperature, high pressure and corrosive environment. It is necessary to establish the reliable and practical technologies for improving and developing the component materials and for evaluating the mechanical properties. Especially, it is very important to investigate the technologies for reactor pressure boundary materials such as reactor vessel and pipings in accordance with their critical roles. Therefore, this study was focused on developing and advancing the microstructural/micro-mechanical evaluation technologies, and on evaluating the neutron irradiation characteristics and radiation effects analysis technology of the reactor pressure boundary materials, and also on establishing a basis of nuclear material property database

  20. Boundary transfer matrices and boundary quantum KZ equations

    Energy Technology Data Exchange (ETDEWEB)

    Vlaar, Bart, E-mail: Bart.Vlaar@nottingham.ac.uk [School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2015-07-15

    A simple relation between inhomogeneous transfer matrices and boundary quantum Knizhnik-Zamolodchikov (KZ) equations is exhibited for quantum integrable systems with reflecting boundary conditions, analogous to an observation by Gaudin for periodic systems. Thus, the boundary quantum KZ equations receive a new motivation. We also derive the commutativity of Sklyanin’s boundary transfer matrices by merely imposing appropriate reflection equations, in particular without using the conditions of crossing symmetry and unitarity of the R-matrix.