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Sample records for polymerization-based bacterial motility

  1. Curved tails in polymerization-based bacterial motility

    NASA Astrophysics Data System (ADS)

    Rutenberg, Andrew D.; Grant, Martin

    2001-08-01

    The curved actin ``comet-tail'' of the bacterium Listeria monocytogenes is a visually striking signature of actin polymerization-based motility. Similar actin tails are associated with Shigella flexneri, spotted-fever Rickettsiae, the Vaccinia virus, and vesicles and microspheres in related in vitro systems. We show that the torque required to produce the curvature in the tail can arise from randomly placed actin filaments pushing the bacterium or particle. We find that the curvature magnitude determines the number of actively pushing filaments, independent of viscosity and of the molecular details of force generation. The variation of the curvature with time can be used to infer the dynamics of actin filaments at the bacterial surface.

  2. Bacterial motility and chemotaxis in shear

    NASA Astrophysics Data System (ADS)

    Rusconi, Roberto; Guasto, Jeffrey S.; Son, Kwangmin; Stocker, Roman

    2011-11-01

    Bacteria often exhibit directed motility (``taxis'') in response to gradients of dissolved resources, like nutrients or oxygen. While we have a detailed understanding of chemotaxis in quiescent environments, it has been largely overlooked how this behavior is affected by fluid flow, despite the ubiquity of flow in bacterial habitats. Here we present experiments on aerotaxis (attraction to dissolved oxygen) of Bacillus subtilis in controlled shear flows. Using novel microfluidic devices we expose bacterial suspensions to steady oxygen gradients, with independent control over shear rates. From single-cell trajectories and the spatial distribution of bacteria, we show that the cell rotation induced by shear reduces the aerotactic performance, demonstrating that hydrodynamic conditions affect bacterial fitness.

  3. A Comprehensive Genetic Characterization of Bacterial Motility

    PubMed Central

    Girgis, Hany S; Liu, Yirchung; Ryu, William S; Tavazoie, Saeed

    2007-01-01

    We have developed a powerful experimental framework that combines competitive selection and microarray-based genetic footprinting to comprehensively reveal the genetic basis of bacterial behaviors. Application of this method to Escherichia coli motility identifies 95% of the known flagellar and chemotaxis genes, and reveals three dozen novel loci that, to varying degrees and through diverse mechanisms, affect motility. To probe the network context in which these genes function, we developed a method that uncovers genome-wide epistatic interactions through comprehensive analyses of double-mutant phenotypes. This allows us to place the novel genes within the context of signaling and regulatory networks, including the Rcs phosphorelay pathway and the cyclic di-GMP second-messenger system. This unifying framework enables sensitive and comprehensive genetic characterization of complex behaviors across the microbial biosphere. PMID:17941710

  4. Bacterial signaling and motility: Sure bets

    SciTech Connect

    Zhulin, Igor B

    2008-01-01

    The IX International Conference on Bacterial Locomotion and Signal Transduction (BLAST IX) was held from 14 to 19 January 2007 in Laughlin, NV, a town in the Mojave Desert on the Nevada-Arizona border near old Route 66 and along the banks of the Colorado River. This area is a home to rattlesnakes, sagebrush, abandoned gold mines, and compulsive gamblers. What better venue could scientists possibly dream of for a professional meeting? So there they were, about 190 scientists gathered in the Aquarius Casino Resort, the largest hotel and casino in Laughlin, discussing the latest advances in the field. Aside from a brief excursion to an abandoned gold mine and a dinner cruise on the Colorado River, the scientists focused on nothing but their data and hypotheses, in spirited arguments and rebuttals, and outlined their visions and future plans in a friendly and open environment. The BLAST IX program was dense, with nearly 50 talks and over 90 posters. For that reason, this meeting report will not attempt to be comprehensive; instead it will first provide general background information on the central topics of the meeting and then highlight only a few talks that were of special interest to us and hopefully to the wider scientific community. We will also attempt to articulate some of the future directions or perspectives to the best of our abilities. The best known and understood bacterial motility mechanism is swimming powered by flagella. The rotation of bacterial flagella drives this form of bacterial movement in an aqueous environment. A bacterial flagellum consists of a helical filament attached to the cell body through a complex structure known as the hook-basal body, which drives flagellar rotation. The essential components of the basal body are the MotA-MotB motor-stator proteins bound to the cytoplasmic membrane. These stator proteins interact with proteins that comprise the supramembrane and cytoplasmic rings, which are components of the motor imbedded in the

  5. Bacterial Motility Reveals Unknown Molecular Organization.

    PubMed

    Duchesne, Ismaël; Rainville, Simon; Galstian, Tigran

    2015-11-17

    The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6±1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds.

  6. Bacterial Motility Reveals Unknown Molecular Organization

    PubMed Central

    Duchesne, Ismaël; Rainville, Simon; Galstian, Tigran

    2015-01-01

    The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6 ± 1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds. PMID:26588572

  7. Flagellated bacterial motility in polymer solutions

    PubMed Central

    Martinez, Vincent A.; Schwarz-Linek, Jana; Reufer, Mathias; Wilson, Laurence G.; Morozov, Alexander N.; Poon, Wilson C. K.

    2014-01-01

    It is widely believed that the swimming speed, v, of many flagellated bacteria is a nonmonotonic function of the concentration, c, of high-molecular-weight linear polymers in aqueous solution, showing peaked v(c) curves. Pores in the polymer solution were suggested as the explanation. Quantifying this picture led to a theory that predicted peaked v(c) curves. Using high-throughput methods for characterizing motility, we measured v and the angular frequency of cell body rotation, Ω, of motile Escherichia coli as a function of polymer concentration in polyvinylpyrrolidone (PVP) and Ficoll solutions of different molecular weights. We find that nonmonotonic v(c) curves are typically due to low-molecular-weight impurities. After purification by dialysis, the measured v(c) and Ω(c) relations for all but the highest-molecular-weight PVP can be described in detail by Newtonian hydrodynamics. There is clear evidence for non-Newtonian effects in the highest-molecular-weight PVP solution. Calculations suggest that this is due to the fast-rotating flagella seeing a lower viscosity than the cell body, so that flagella can be seen as nano-rheometers for probing the non-Newtonian behavior of high polymer solutions on a molecular scale. PMID:25468981

  8. Flagellated bacterial motility in polymer solutions.

    PubMed

    Martinez, Vincent A; Schwarz-Linek, Jana; Reufer, Mathias; Wilson, Laurence G; Morozov, Alexander N; Poon, Wilson C K

    2014-12-16

    It is widely believed that the swimming speed, v, of many flagellated bacteria is a nonmonotonic function of the concentration, c, of high-molecular-weight linear polymers in aqueous solution, showing peaked v(c) curves. Pores in the polymer solution were suggested as the explanation. Quantifying this picture led to a theory that predicted peaked v(c) curves. Using high-throughput methods for characterizing motility, we measured v and the angular frequency of cell body rotation, Ω, of motile Escherichia coli as a function of polymer concentration in polyvinylpyrrolidone (PVP) and Ficoll solutions of different molecular weights. We find that nonmonotonic v(c) curves are typically due to low-molecular-weight impurities. After purification by dialysis, the measured v(c) and Ω(c) relations for all but the highest-molecular-weight PVP can be described in detail by Newtonian hydrodynamics. There is clear evidence for non-Newtonian effects in the highest-molecular-weight PVP solution. Calculations suggest that this is due to the fast-rotating flagella seeing a lower viscosity than the cell body, so that flagella can be seen as nano-rheometers for probing the non-Newtonian behavior of high polymer solutions on a molecular scale.

  9. Polymer confinement and bacterial gliding motility

    NASA Astrophysics Data System (ADS)

    Jeon, J.; Dobrynin, A. V.

    2005-07-01

    Cyanobacteria and myxobacteria use slime secretion for gliding motility over surfaces. The slime is produced by the nozzle-like pores located on the bacteria surface. To understand the mechanism of gliding motion and its relation to slime polymerization, we have performed molecular dynamics simulations of a molecular nozzle with growing inside polymer chains. These simulations show that the compression of polymer chains inside the nozzle is a driving force for propulsion. There is a linear relationship between the average nozzle velocity and the chain polymerization rate with a proportionality coefficient dependent on the geometric characteristics of the nozzle such as its length and friction coefficient. This minimal model of the molecular engine was used to explain the gliding motion of bacteria over surfaces.

  10. Study of bacterial motility using optical tweezers

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Suddhashil

    Bacteria are arguably the simplest of known microorganisms, forming a fundamental part of the world we live in. Many functions they perform are found in scaled-up versions in higher organisms. Among many advanced functions, bacteria possess the ability to move in search for nutrients and favorable growth conditions. Measurement of the dynamical variables associated with bacterial swimming has proven to be difficult due to the lack of an accurate and convenient tool. In the past optical traps have been used for the manipulation of microscopic objects and measurement of minute forces. Herein, I have devised techniques for use of optical traps for direct measurement of the dynamics of bacterial swimming and chemotaxis, shedding light on the propulsion apparatus and sensory systems. A detailed analysis is performed to explore the effects of non-local hydrodynamic interactions on the swimming of single cells. Due to the lack of reliable measurement techniques, experimentalists often use theoretical models to estimate bacterial dynamics, the validity of which are tested. I emphasize the shortcomings of the very popular Resistive Force Theory (RFT) and indicate how the more rigorous Slender Body Theory (SBT) is able to overcome the limitations. In addition the chemotaxis of the marine bacterial strain Vibrio alginolyticus is studied with the revelation of a previously unknown chemotactic mechanism. Direct observations showed that these cells are able to bend their flagella to impart direction changes, which is paramount for an effective search strategy. This interesting find opens several intriguing questions pertaining to chemotaxis.

  11. Polymer confinement and bacterial gliding motility

    NASA Astrophysics Data System (ADS)

    Jeon, Junhwan; Dobrynin, Andrey

    2006-03-01

    Cyanobacteria and myxobacteria use slime secretion for gliding motility over surfaces. In cyanobacteria the slime is extruded from the nozzle-like pores of 14-16 nm outer diameter and approximately 7nm inner diameter located near the septa that separate the cells of a filament. The pores are inclined at an angle of 30-40 degrees relative to the cell axes, and are oppositely directed on both sides of the septum. Such pore orientation provides directionality for the slime secretion as well as cell motion. To understand the mechanism of gliding motion and its relation to slime polymerization, we have performed molecular dynamics simulations of a molecular nozzle with growing inside polymer chains. These simulations show that the compression of polymer chains inside the nozzle is a driving force for its propulsion. There is a linear relationship between the average nozzle velocity and the chain polymerization rate with a proportionality coefficient dependent on the geometric characteristics of the nozzle such as its length and friction coefficient. This minimal model of the molecular engine was used to explain the gliding motion of cyanobacteria and myxobacteria over surfaces.

  12. Effect of Bacterial Motility on Contaminant Mixing in Porous Media

    NASA Astrophysics Data System (ADS)

    Singh, R.; Olson, M. S.; Bioremediation At Drexel

    2010-12-01

    Groundwater flow is typically characterized by laminar flow and therefore contaminant mixing limited conditions prevail in subsurface environments. The presence of porous media introduces tortuosity to groundwater flow paths, thereby enhancing contaminant mixing. In addition, bacterial motility is reported to induce movement in their surrounding liquid, which may enhance contaminant mixing. Enhancement of chemical diffusion coefficients in bulk fluid due to bacterial random motility and chemotaxis has been already reported in literature. The aim of this study is to investigate the effect of bacterial motility on contaminant mixing in the presence of porous media. A microfluidic device was designed and fabricated using standard photolithography and soft-lithography techniques to simulate a contaminant plume in subsurface porous media due to leakage of an underground storage tank. A non-reactive conservative tracer, Dextran solution labeled with FITC (fluorescein isothiocyanate), was used as surrogate for the contaminant and the motile bacterial strain Escherichia coli HCB33 (wild type) was used for the experiments to enhance contaminant mixing. Images were obtained at various cross-sections along the device and fluorescence intensity profile distributions were analyzed to determine the transverse dispersion of the contaminant. Enhancement in contaminant mixing was assessed by comparing the contaminant transverse dispersion coefficients (Dyi) in porous media in presence of motile bacteria, immobilized bacteria, and with no bacteria. In order to quantify the contaminant dispersion coefficients under the various test conditions, experimental data obtained were fitted to concentration profiles predicted by the contaminant advection-dispersion equation for the given experimental conditions (Figure 1). The transverse dispersion coefficient values obtained in the presence of motile bacteria (Dymb)and with no bacteria (Dynb) were 2.49 x 10-4 cm2/s and 1.39 x 10-4 cm2/s

  13. Preparation, imaging, and quantification of bacterial surface motility assays.

    PubMed

    Morales-Soto, Nydia; Anyan, Morgen E; Mattingly, Anne E; Madukoma, Chinedu S; Harvey, Cameron W; Alber, Mark; Déziel, Eric; Kearns, Daniel B; Shrout, Joshua D

    2015-04-07

    Bacterial surface motility, such as swarming, is commonly examined in the laboratory using plate assays that necessitate specific concentrations of agar and sometimes inclusion of specific nutrients in the growth medium. The preparation of such explicit media and surface growth conditions serves to provide the favorable conditions that allow not just bacterial growth but coordinated motility of bacteria over these surfaces within thin liquid films. Reproducibility of swarm plate and other surface motility plate assays can be a major challenge. Especially for more "temperate swarmers" that exhibit motility only within agar ranges of 0.4%-0.8% (wt/vol), minor changes in protocol or laboratory environment can greatly influence swarm assay results. "Wettability", or water content at the liquid-solid-air interface of these plate assays, is often a key variable to be controlled. An additional challenge in assessing swarming is how to quantify observed differences between any two (or more) experiments. Here we detail a versatile two-phase protocol to prepare and image swarm assays. We include guidelines to circumvent the challenges commonly associated with swarm assay media preparation and quantification of data from these assays. We specifically demonstrate our method using bacteria that express fluorescent or bioluminescent genetic reporters like green fluorescent protein (GFP), luciferase (lux operon), or cellular stains to enable time-lapse optical imaging. We further demonstrate the ability of our method to track competing swarming species in the same experiment.

  14. Immobilization of motile bacterial cells via dip-pen nanolithography

    NASA Astrophysics Data System (ADS)

    Nyamjav, Dorjderem; Rozhok, Sergey; Holz, Richard C.

    2010-06-01

    A strategy to bind bacterial cells to surfaces in a directed fashion via dip-pen nanolithography (DPN) is presented. Cellular attachment to pre-designed DPN generated microarrays was found to be dependent on the shape and size of the surface feature. While this observation is likely due in part to a dense, well formed mercaptohexadecanoic acid (MHA) monolayer generated via DPN, it may also simply be due to the physical shape of the surface structure. Motile Pseudomonas aeruginosa bacterial cells were observed to bind to DPN generated mercaptohexadecanoic acid/poly-L-lysine (MHA/PLL) line patterns, 'blocks' made up of eight lines with 100 nm spacings, with ~ 80% occupancy. Cellular binding to these 'block' surface structures occurs via an electrostatic interaction between negatively charged groups on the bacterial cell surface and positively charged poly-L-lysine (PLL) assemblies. These data indicate that these DPN generated 'block' surface structures provide a promising footprint for the attachment of motile bacterial cells that may find utility in cell based biosensors or single cell studies.

  15. Bacterial motility near crude oil and water interface

    NASA Astrophysics Data System (ADS)

    Rodríguez, Jomayra E. Sánchez; Molaei, Mehdi; Sheng, Jian

    2013-11-01

    Study of biodegradation of crude oil by microbes requires profound understanding of their movement near oil-water interface as well as in/out of phase movement. Bacterial motilities are known to be modified by the presence of an interface through hydrodynamic interactions in addition to the chemotactic behavior towards the oil phase. Using digital holographic microscopy and phase contrast microscopy, we study locomotion of Pseudomonas sp (P62), a well-known hydrocarbon degrader under various chemo- and mechano-environmental conditions. Baseline experiments have been performed at different nutrient levels and Ion levels to identify effects of chemical environment on cell motility. Utilizing novel microfluidics and surface functionalization, we have established a stable vertical oil-water interface between top and bottom surfaces of the microfluidics, which allow clear optical access to observe bacterial movement near the interface. Three-dimensional trajectories of bacteria, obtained by analyzing recorded by digital holography microscopy, enable us to characterize bacterial swimming and orientation near interfaces. Chemotaxis velocity and swimming induced dispersion are measured directly as well as cell concentration distributions with respect to the distance to the interface. NIH, NSF, GoMRI.

  16. Gains of Bacterial Flagellar Motility in a Fungal World

    PubMed Central

    Pion, Martin; Bshary, Redouan; Bindschedler, Saskia; Filippidou, Sevasti; Wick, Lukas Y.; Job, Daniel

    2013-01-01

    The maintenance of energetically costly flagella by bacteria in non-water-saturated media, such as soil, still presents an evolutionary conundrum. Potential explanations have focused on rare flooding events allowing dispersal. Such scenarios, however, overlook bacterial dispersal along mycelia as a possible transport mechanism in soils. The hypothesis tested in this study is that dispersal along fungal hyphae may lead to an increase in the fitness of flagellated bacteria and thus offer an alternative explanation for the maintenance of flagella even in unsaturated soils. Dispersal along fungal hyphae was shown for a diverse array of motile bacteria. To measure the fitness effect of dispersal, additional experiments were conducted in a model system mimicking limited dispersal, using Pseudomonas putida KT2440 and its nonflagellated (ΔfliM) isogenic mutant in the absence or presence of Morchella crassipes mycelia. In the absence of the fungus, flagellar motility was beneficial solely under conditions of water saturation allowing dispersal, while under conditions limiting dispersal, the nonflagellated mutant exhibited a higher level of fitness than the wild-type strain. In contrast, in the presence of a mycelial network under conditions limiting dispersal, the flagellated strain was able to disperse using the mycelial network and had a higher level of fitness than the mutant. On the basis of these results, we propose that the benefit of mycelium-associated dispersal helps explain the persistence of flagellar motility in non-water-saturated environments. PMID:23995942

  17. Gains of bacterial flagellar motility in a fungal world.

    PubMed

    Pion, Martin; Bshary, Redouan; Bindschedler, Saskia; Filippidou, Sevasti; Wick, Lukas Y; Job, Daniel; Junier, Pilar

    2013-11-01

    The maintenance of energetically costly flagella by bacteria in non-water-saturated media, such as soil, still presents an evolutionary conundrum. Potential explanations have focused on rare flooding events allowing dispersal. Such scenarios, however, overlook bacterial dispersal along mycelia as a possible transport mechanism in soils. The hypothesis tested in this study is that dispersal along fungal hyphae may lead to an increase in the fitness of flagellated bacteria and thus offer an alternative explanation for the maintenance of flagella even in unsaturated soils. Dispersal along fungal hyphae was shown for a diverse array of motile bacteria. To measure the fitness effect of dispersal, additional experiments were conducted in a model system mimicking limited dispersal, using Pseudomonas putida KT2440 and its nonflagellated (ΔfliM) isogenic mutant in the absence or presence of Morchella crassipes mycelia. In the absence of the fungus, flagellar motility was beneficial solely under conditions of water saturation allowing dispersal, while under conditions limiting dispersal, the nonflagellated mutant exhibited a higher level of fitness than the wild-type strain. In contrast, in the presence of a mycelial network under conditions limiting dispersal, the flagellated strain was able to disperse using the mycelial network and had a higher level of fitness than the mutant. On the basis of these results, we propose that the benefit of mycelium-associated dispersal helps explain the persistence of flagellar motility in non-water-saturated environments.

  18. A Mach-Zender Holographic Microscope for Quantifying Bacterial Motility

    NASA Astrophysics Data System (ADS)

    Niraula, B.; Nadeau, J. L.; Serabyn, E.; Wallace, J. K.; Liewer, K.; Kuhn, J.; Graff, E.; Lindensmith, C.

    2014-12-01

    New microscopic techniques have revolutionized cell biology over the past two decades. However, there are still biological processes whose details elude us, especially those involving motility: e.g. feeding behavior of microorganisms in the ocean, or migration of cancer cells to form metastases. Imaging prokaryotes, which range in size from several hundred nm to a few microns, is especially challenging. An emerging technique to address these issues is Digital Holographic Microscopy (DHM). DHM is an imaging technique that uses the interference of light to record and reproduce three-dimensional magnified images of objects. This approach has several advantages over ordinary brightfield microscopy for fieldwork: a larger depth of field, hands-off operation, robustness regarding environmental conditions, and large sampling volumes with quantitative 3D records of motility behavior. Despite these promising features, real-time DHM was thought to be impractical for technological and computational reasons until recently, and there has so far been very limited application of DHM to biology. Most existing instruments are limited in performance by their particular (e.g. in-line, lens-less, phase-shifting) approach to holography. These limitations can be mitigated with an off-axis dual-path configuration. Here we describe the design and implementation of a design for a Mach-Zehnder-type holographic microscope with diffraction-limited lateral resolution, with intended applications in environmental microbiology. We have achieved sub-micron resolution and three-dimensional tracking of prokaryotic and eukaryotic test strains designed to represent different modes and speeds of microbial motility. Prokaryotes are Escherichia coli, Vibrio alginolyticus, and Bacillus subtilis. Each shows a characteristic motility pattern, as we illustrate in holographic videos in sample chambers 0.6 mm in depth. The ability to establish gradients of attractants with bacterial taxis towards the

  19. Exopolysaccharide microchannels direct bacterial motility and organize multicellular behavior

    PubMed Central

    Berleman, James E; Zemla, Marcin; Remis, Jonathan P; Liu, Hong; Davis, Annie E; Worth, Alexandra N; West, Zachary; Zhang, Angela; Park, Hanwool; Bosneaga, Elena; van Leer, Brandon; Tsai, Wenting; Zusman, David R; Auer, Manfred

    2016-01-01

    The myxobacteria are a family of soil bacteria that form biofilms of complex architecture, aligned multilayered swarms or fruiting body structures that are simple or branched aggregates containing myxospores. Here, we examined the structural role of matrix exopolysaccharide (EPS) in the organization of these surface-dwelling bacterial cells. Using time-lapse light and fluorescence microscopy, as well as transmission electron microscopy and focused ion beam/scanning electron microscopy (FIB/SEM) electron microscopy, we found that Myxococcus xanthus cell organization in biofilms is dependent on the formation of EPS microchannels. Cells are highly organized within the three-dimensional structure of EPS microchannels that are required for cell alignment and advancement on surfaces. Mutants lacking EPS showed a lack of cell orientation and poor colony migration. Purified, cell-free EPS retains a channel-like structure, and can complement EPS− mutant motility defects. In addition, EPS provides the cooperative structure for fruiting body formation in both the simple mounds of M. xanthus and the complex, tree-like structures of Chondromyces crocatus. We furthermore investigated the possibility that EPS impacts community structure as a shared resource facilitating cooperative migration among closely related isolates of M. xanthus. PMID:27152937

  20. Exopolysaccharide microchannels direct bacterial motility and organize multicellular behavior.

    PubMed

    Berleman, James E; Zemla, Marcin; Remis, Jonathan P; Liu, Hong; Davis, Annie E; Worth, Alexandra N; West, Zachary; Zhang, Angela; Park, Hanwool; Bosneaga, Elena; van Leer, Brandon; Tsai, Wenting; Zusman, David R; Auer, Manfred

    2016-11-01

    The myxobacteria are a family of soil bacteria that form biofilms of complex architecture, aligned multilayered swarms or fruiting body structures that are simple or branched aggregates containing myxospores. Here, we examined the structural role of matrix exopolysaccharide (EPS) in the organization of these surface-dwelling bacterial cells. Using time-lapse light and fluorescence microscopy, as well as transmission electron microscopy and focused ion beam/scanning electron microscopy (FIB/SEM) electron microscopy, we found that Myxococcus xanthus cell organization in biofilms is dependent on the formation of EPS microchannels. Cells are highly organized within the three-dimensional structure of EPS microchannels that are required for cell alignment and advancement on surfaces. Mutants lacking EPS showed a lack of cell orientation and poor colony migration. Purified, cell-free EPS retains a channel-like structure, and can complement EPS(-) mutant motility defects. In addition, EPS provides the cooperative structure for fruiting body formation in both the simple mounds of M. xanthus and the complex, tree-like structures of Chondromyces crocatus. We furthermore investigated the possibility that EPS impacts community structure as a shared resource facilitating cooperative migration among closely related isolates of M. xanthus.

  1. Bacterial haptotaxis: Effect of auto-attraction and bacterial motility on microcolony formation

    NASA Astrophysics Data System (ADS)

    Beckerman, Bernard; Zhao, Kun; Wong, Gerard C. L.; Luijten, Erik

    Recent work has demonstrated that surface-adhered Pseudomonas aeruginosa tend to self-organize into microcolonies using a positive-feedback mechanism mediated by the exopolysaccharide Psl, which the bacteria secrete as they traverse the surface. We elucidate this colony-nucleation process and explore how it is influenced by the deposition rate of Psl and by bacterial motility. A detailed analysis of the data presented in our earlier study, in combination with additional simulations, provides further insight into the exploratory strategy of P. aeruginosa. Specifically, the isogenic bacterial population is found to exhibit polyphenic motility. As a result, the bacterial population splits into two distinct subpopulations when depositing Psl, those that become trapped in their self-deposited Psl and those that move sufficiently quickly to escape their Psl beds and explore the surface. We perform computer simulations in which we adjust the relative prevalence of these subpopulations by varying the Psl deposition rate and find that there is a trade-off between surface exploration, microcolony diversity and microcolony fortification.

  2. Inhibition of bacterial motility and spreading via release of cranberry derived materials from silicone substrates.

    PubMed

    Chan, Michelle; Hidalgo, Gabriela; Asadishad, Bahareh; Almeida, Sergio; Muja, Naser; Mohammadi, Maziar Shah; Nazhat, Showan N; Tufenkji, Nathalie

    2013-10-01

    The motility of bacteria plays a key role in their colonization of surfaces during infection. Derivatives of cranberry fruit have been shown to interfere with bacterial motility. Herein, we report on the incorporation of cranberry derived materials (CDMs) into silicone substrates with the aim of impairing bacterial pathogen motility and spreading on the substrate surface. The release of CDMs from the silicone substrates when soaking in an aqueous medium was quantified for a period of 24h. Next, we showed that CDMs released from two silicone substrates remain bioactive as they downregulate the expression of the flagellin gene of two key uropathogens - Escherichia coli CFT073 and Proteus mirabilis HI4320. Furthermore, we demonstrate that CDM-modified silicone inhibits the swarming motility of P. mirabilis, an aggressive swarmer. The bioactive, CDM-modified substrates can find broad applications in the medical device and food industries where the impairment of bacterial colonization of surfaces is of paramount importance.

  3. Cell motility and antibiotic tolerance of bacterial swarms

    NASA Astrophysics Data System (ADS)

    Zuo, Wenlong

    Many bacteria species can move across moist surfaces in a coordinated manner known as swarming. It is reported that swarm cells show higher tolerance to a wide variety of antibiotics than planktonic cells. We used the model bacterium E. coli to study how motility affects the antibiotic tolerance of swarm cells. Our results provide new insights for the control of pathogenic invasion via regulating cell motility. Mailing address: Room 306 Science Centre North Block, The Chinese University of Hong Kong, Shatin, N.T. Hong Kong SAR. Phone: +852-3943-6354. Fax: +852-2603-5204. E-mail: zwlong@live.com.

  4. Using experimental evolution to explore natural patterns between bacterial motility and resistance to bacteriophages.

    PubMed

    Koskella, Britt; Taylor, Tiffany B; Bates, Jennifer; Buckling, Angus

    2011-11-01

    Resistance of bacteria to phages may be gained by alteration of surface proteins to which phages bind, a mechanism that is likely to be costly as these molecules typically have critical functions such as movement or nutrient uptake. To address this potential trade-off, we combine a systematic study of natural bacteria and phage populations with an experimental evolution approach. We compare motility, growth rate and susceptibility to local phages for 80 bacteria isolated from horse chestnut leaves and, contrary to expectation, find no negative association between resistance to phages and bacterial motility or growth rate. However, because correlational patterns (and their absence) are open to numerous interpretations, we test for any causal association between resistance to phages and bacterial motility using experimental evolution of a subset of bacteria in both the presence and absence of naturally associated phages. Again, we find no clear link between the acquisition of resistance and bacterial motility, suggesting that for these natural bacterial populations, phage-mediated selection is unlikely to shape bacterial motility, a key fitness trait for many bacteria in the phyllosphere. The agreement between the observed natural pattern and the experimental evolution results presented here demonstrates the power of this combined approach for testing evolutionary trade-offs.

  5. Bacterial Shape and ActA Distribution Affect Initiation of Listeria monocytogenes Actin-Based Motility

    PubMed Central

    Rafelski, Susanne M.; Theriot, Julie A.

    2005-01-01

    We have examined the process by which the intracellular bacterial pathogen Listeria monocytogenes initiates actin-based motility and determined the contribution of the variable surface distribution of the ActA protein to initiation and steady-state movement. To directly correlate ActA distributions to actin dynamics and motility of live bacteria, ActA was fused to a monomeric red fluorescent protein (mRFP1). Actin comet tail formation and steady-state bacterial movement rates both depended on ActA distribution, which in turn was tightly coupled to the bacterial cell cycle. Motility initiation was found to be a highly complex, multistep process for bacteria, in contrast to the simple symmetry breaking previously observed for ActA-coated spherical beads. F-actin initially accumulated along the sides of the bacterium and then slowly migrated to the bacterial pole expressing the highest density of ActA as a tail formed. Early movement was highly unstable with extreme changes in speed and frequent stops. Over time, saltatory motility and sensitivity to the immediate environment decreased as bacterial movement became robust at a constant steady-state speed. PMID:15980176

  6. The role of motility and chemotaxis in the bacterial colonization of protected surfaces

    PubMed Central

    Tamar, Einat; Koler, Moriah; Vaknin, Ady

    2016-01-01

    Internal epithelial surfaces in humans are both oxygenated and physically protected by a few hundred microns thick hydrogel mucosal layer, conditions that might support bacterial aerotaxis. However, the potential role of aerotaxis in crossing such a thin hydrogel layer is not clear. Here, we used a new setup to study the potential role of motility and chemotaxis in the bacterial colonization of surfaces covered by a thin hydrogel layer and subjected to a vertical oxygen gradient. Using the bacterium Escherichia coli, we show that both non-motile and motile-but-non-chemotactic bacteria could barely reach the surface. However, an acquired mutation in the non-chemotactic bacteria that altered their inherent swimming behavior led to a critical enhancement of surface colonization. Most chemotactic strains accumulated within the bulk of the hydrogel layer, except for the MG1655 strain, which showed a unique tendency to accumulate directly at the oxygenated surface and thus exhibited distinctly enhanced colonization. Even after a long period of bacterial growth, non-motile bacteria could not colonize the hydrogel. Thus, switching motility, which can be spontaneously acquired or altered in vivo, is critical for the colonization of such protected surfaces, whereas aerotaxis capacity clearly expedites surface colonization, and can lead to diverse colonization patterns. PMID:26792493

  7. Asynchrony in the growth and motility responses to environmental changes by individual bacterial cells

    SciTech Connect

    Umehara, Senkei; Hattori, Akihiro; Inoue, Ippei; Yasuda, Kenji . E-mail: yasuda.bmi@tmd.ac.jp

    2007-05-04

    Knowing how individual cells respond to environmental changes helps one understand phenotypic diversity in a bacterial cell population, so we simultaneously monitored the growth and motility of isolated motile Escherichia coli cells over several generations by using a method called on-chip single-cell cultivation. Starved cells quickly stopped growing but remained motile for several hours before gradually becoming immotile. When nutrients were restored the cells soon resumed their growth and proliferation but remained immotile for up to six generations. A flagella visualization assay suggested that deflagellation underlies the observed loss of motility. This set of results demonstrates that single-cell transgenerational study under well-characterized environmental conditions can provide information that will help us understand distinct functions within individual cells.

  8. Bacterial spread from cell to cell: beyond actin-based motility.

    PubMed

    Kuehl, Carole J; Dragoi, Ana-Maria; Talman, Arthur; Agaisse, Hervé

    2015-09-01

    Several intracellular pathogens display the ability to propagate within host tissues by displaying actin-based motility in the cytosol of infected cells. As motile bacteria reach cell-cell contacts they form plasma membrane protrusions that project into adjacent cells and resolve into vacuoles from which the pathogen escapes, thereby achieving spread from cell to cell. Seminal studies have defined the bacterial and cellular factors that support actin-based motility. By contrast, the mechanisms supporting the formation of protrusions and their resolution into vacuoles have remained elusive. Here, we review recent advances in the field showing that Listeria monocytogenes and Shigella flexneri have evolved pathogen-specific mechanisms of bacterial spread from cell to cell.

  9. Impact of dissolved organic matter on bacterial tactic motility, attachment, and transport.

    PubMed

    Jimenez-Sanchez, Celia; Wick, Lukas Y; Cantos, Manuel; Ortega-Calvo, José-Julio

    2015-04-07

    Bacterial dispersal is a key driver of the ecology of microbial contaminant degradation in soils. This work investigated the role of dissolved organic matter (DOM) in the motility, attachment, and transport of the soil bacterium Pseudomonas putida G7 in saturated porous media. The study is based on the hypothesis that DOM quality is critical to triggering tactic motility and, consequently, affects bacterial transport and dispersal. Sunflower root exudates, humic acids (HA), and the synthetic oleophilic fertilizer S-200 were used as representatives of fresh, weathered, and artificially processed DOM with high nitrogen and phosphorus contents, respectively. We studied DOM levels of 16-130 mg L(-1), which are representative of DOM concentrations typically found in agricultural soil pore water. In contrast to its responses to HA and S-200, strain G7 exhibited a tactic behavior toward root exudates, as quantified by chemotaxis assays and single-cell motility observations. All DOM types promoted bacterial transport through sand at high concentrations (∼ 130 mg L(-1)). At low DOM concentrations (∼ 16 mg L(-1)), the enhancement occurred only in the presence of sunflower root exudates, and this enhancement did not occur with G7 bacteria devoid of flagella. Our results suggest that tactic DOM effectors strongly influence bacterial transport and the interception probability of motile bacteria by collector surfaces.

  10. Enhancement of flagellated bacterial motility in polymer solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Wenyu; Sha, Sha; Pelcovits, Robert; Tang, Jay

    2015-11-01

    Measurements of the swimming speed of many species of flagellated bacteria in polymer solutions have shown that with the addition of high molecular weight polymers, the speed initially increases as a function of the kinematic viscosity. It peaks at around 1.5-2 cP with typically 10-30% higher values than in cell media without added polymers (~ 1 cP). Past the peak, the average speed gradually decreases as the solution becomes more viscous. Swimming motility persists until solution viscosity reaches 5-10 cP. Models have been proposed to account for this behavior, and the magnitude of the peak becomes a crucial test of theoretical predictions. The status of the field is complicated in light of a recent report (Martinez et al., PNAS, 2014), stressing that low-molecular weight impurities account for the peaked speed-viscosity curves in some cases. We measured the swimming speed of a uni-flagellated bacterium, caulobacter crescentus, in solutions of a number of polymers of several different sizes. Our findings confirm the peaked speed-viscosity curve, only as the molecular weight of the flexible polymers used surpassed ~ 50,000 da. The threshold molecular weight required to augment swimming speed varies somewhat with the polymer species, but it generally corresponds to radius of gyration over tens of nanometers. This general feature is consistent with the model of Powers et al. (Physics of Fluid, 2009), predicting that nonlinear viscoelasticity of the fluid enhances swimming motility. Work Supported by the NSF Fluid Physics Program (Award number CBET 1438033).

  11. Bacterial flagellar motility on hydrated rough surfaces controlled by aqueous film thickness and connectedness

    PubMed Central

    Tecon, Robin; Or, Dani

    2016-01-01

    Recent studies have shown that rates of bacterial dispersion in soils are controlled by hydration conditions that define size and connectivity of the retained aqueous phase. Despite the ecological implications of such constraints, microscale observations of this phenomenon remain scarce. Here, we quantified aqueous film characteristics and bacterial flagellated motility in response to systematic variations in microhydrological conditions on porous ceramic surfaces that mimic unsaturated soils. We directly measured aqueous film thickness and documented its microscale heterogeneity. Flagellar motility was controlled by surface hydration conditions, as cell velocity decreased and dispersion practically ceased at water potentials exceeding –2 kPa (resulting in thinner and disconnected liquid films). The fragmentation of aquatic habitats was delineated indirectly through bacterial dispersal distances within connected aqueous clusters. We documented bacterial dispersal radii ranging from 100 to 10 μm as the water potential varied from 0 to –7 kPa, respectively. The observed decrease of flagellated velocity and dispersal ranges at lower matric potentials were in good agreement with mechanistic model predictions. Hydration-restricted habitats thus play significant role in bacterial motility and dispersal, which has potentially important impact on soil microbial ecology and diversity. PMID:26757676

  12. Effect of cell physicochemical characteristics and motility on bacterial transport in groundwater

    NASA Astrophysics Data System (ADS)

    Becker, Matthew W.; Collins, Samantha A.; Metge, David W.; Harvey, Ronald W.; Shapiro, Allen M.

    2004-04-01

    The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates.

  13. Effect of cell physicochemical characteristics and motility on bacterial transport in groundwater.

    PubMed

    Becker, Matthew W; Collins, Samantha A; Metge, David W; Harvey, Ronald W; Shapiro, Allen M

    2004-04-01

    The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates.

  14. Effect of cell physicochemical characteristics and motility on bacterial transport in groundwater

    USGS Publications Warehouse

    Becker, M.W.; Collins, S.A.; Metge, D.W.; Harvey, R.W.; Shapiro, A.M.

    2004-01-01

    The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates. ?? 2003 Elsevier B.V. All rights reserved.

  15. Bacterial tracking of motile algae assisted by algal cell's vorticity field.

    PubMed

    Locsei, J T; Pedley, T J

    2009-07-01

    Previously published experimental work by other authors has shown that certain motile marine bacteria are able to track free-swimming algae by executing a zigzag path and steering toward the algae at each turn. Here, we propose that the apparent steering behaviour could be a hydrodynamic effect, whereby an algal cell's vorticity and strain-rate fields rotate a pursuing bacterial cell in the appropriate direction. Using simplified models for the bacterial and algal cells, we numerically compute the trajectory of a bacterial cell and demonstrate the plausibility of this hypothesis.

  16. Dynamic laser speckle to detect motile bacterial response of Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Sendra, H.; Murialdo, S.; Passoni, L.

    2007-11-01

    This proposal deals with the technique for detection of motile response of Pseudomonas aeruginosa using dynamic laser speckle or biospeckle as an alternative method. The study of bacterial displacement plays an essential role in biocatalysts processes and biodegradation. Hence, some biodegrading enzymes are benign catalytic that could be used for the production of industrially useful compounds as well as in wastewater treatments. This work presents an experimental set up and a computational process using frame sequences of dynamic laser speckle as a novel application. The objective was the detection of different levels of motility in bacteria. The encouraging results were achieved through a direct and non invasive observation method of the phenomenon.

  17. Effect of Porous Media Particle Size on Bacterial Motility and Chemotaxis

    NASA Astrophysics Data System (ADS)

    Olson, M. S.; Smith, J. A.; Ford, R. M.; Fernandez, E. J.

    2003-12-01

    Many soil-inhabiting bacteria that degrade chemical contaminants are both motile and chemotactic. Chemotaxis refers to the ability of bacteria to sense pollutant concentration gradients in water and preferentially swim toward regions of high pollutant concentration, and is thought to be important in guiding subsurface microbial populations toward chemical contaminants. Bacterial motion consists of a series of smooth-swimming runs interrupted by changes in direction. In the presence of a chemical gradient, bacteria bias their frequency of changing direction and demonstrate longer run lengths in the direction of increasing attractant concentration. One concern when studying bacterial chemotaxis in porous media is that in small pores, the porous media may interrupt the extended run lengths of bacteria swimming in the direction of a positive chemical gradient. The purpose of this study is to examine how a decrease in particle size affects the motility and chemotactic response of bacteria traveling through porous media. We employ an innovative technique for noninvasive visualization of changes in bacterial density distributions in a packed column as a function of time. Paramagnetic magnetite particles are attached to the surface of Pseudomonas putida F1 cells using an antibody. Bacterial distributions within a column of glass-coated polystyrene beads are imaged using magnetic resonance imaging (MRI), with a spatial resolution of 300 μ m. Experiments are conducted with both 250-300 μ m beads and 90-150 μ m beads. Bacteria labeled with magnetite are introduced into a specially designed chromatography column packed with glass-coated polystyrene beads. Bacterial migration is monitored over time using MRI, with and without the presence of a chemical gradient of trichloroethylene (TCE). Comparisons of the motility and chemotactic transport coefficients for Pseudomonas putida F1 cells traveling through different-sized samples of porous media in the presence of TCE will be

  18. The Salmonella enterica serovar Typhimurium QseB Response Regulator Negatively Regulates Bacterial Motility and Swine Colonization in the Absence of the QseC Sensor Kinase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Typhimurium (S. Typhimurium) responds to the catecholamine, norepinephrine by increasing bacterial growth and enhancing motility. In this study, iron with or without the siderophore, ferrioxamine E also enhanced bacterial motility. Iron-enhanced motility was growth-rate ...

  19. Measurement of Bacterial Motility and Chemotaxis in Porous Media using MRI

    NASA Astrophysics Data System (ADS)

    Olson, M. S.; Smith, J. A.; Ford, R. M.; Fernandez, E. J.

    2002-05-01

    In this study, we analyze the effects of random motility and chemotaxis on bacterial transport through porous media. Chemotaxis refers to the ability of bacteria to sense pollutant concentration gradients in water and preferentially swim toward regions of high pollutant concentration. Chemotaxis has been documented to occur in bulk aqueous systems, but it has not been previously verified in water-saturated porous media. We employ an innovative technique for noninvasive visualization of changes in bacterial density distributions in a packed column as a function of time. Paramagnetic magnetite particles are attached to the surface of Pseudomonas putida F1 cells using an antibody. Bacterial distributions within a column of glass-coated polystyrene beads are imaged using magnetic resonance imaging (MRI), with a spatial resolution of 300 mm. Bacteria labeled with magnetite are introduced into one half of a specially designed chromatography column packed with glass-coated polystyrene beads. Impinging flow is used to create an initial step change in bacterial concentration and bacterial migration is monitored over time using MRI. The movement of P. putida F1 through the porous medium is described by an effective random motility coefficient of 1.0x10-7 cm2/sec, as determined by analyzing the temporal concentration profiles. Similar experiments measuring the diffusion of MnCl2 rather than labeled bacteria indicate that the effective tortuosity of the packed column is 7.09 +/- 0.28. This technique is further applied to study the migration of P. putida F1 in the presence of the chemical attractant trichloroethylene (TCE). Simulations indicate a 12% increase in bacterial concentration in the region of favorable TCE gradient. Results and analyses of chemotaxis experiments will be presented and discussed.

  20. Bacterial Motility As a Biosignature: Tests at Icy Moon Analogue Sites

    NASA Astrophysics Data System (ADS)

    Nadeau, J. L.; Lindensmith, C.; Deming, J. W.; Stocker, R.; Graff, E.; Serabyn, E.; Wallace, J. K.; Liewer, K.; Kuhn, J.

    2014-12-01

    Extraterrestrial life in our Solar System, if present, is almost certain to be microbial. Methods and technologies for unambiguous detection of living or extinct microorganisms are needed for life-detection missions to the Jovian and Saturnian moons, where liquid water is known to exist. Our research focuses specifically on microbial meaningful motion as a biosignature—"waving crowds" at the micron scale. Digital Holographic Microscopy (DHM) is an excellent tool for unambiguous identification of bacterial and protozoal swimming, even in the presence of turbidity, drift, and currents. The design of a holographic instrument with bacteria scale resolution was described in the previous talk. In this presentation, we will illustrate the design challenges for construction of a field instrument for extreme environments and space, and present plans for scientific investigations at analogue sites for the coming season. The challenges of creating a field instrument involve performance trade-offs, the ability to operate at extreme temperatures, and handling large volumes of data. A fully autonomous instrument without external cables or power is also desirable, and this is something that previous holographic instruments have not achieved. The primary issues for space exploration are identification of a laser and drive electronics that are qualified for the expected radiation environments of the moons around gas giant planets. Tests in Earth analogue environments will establish performance parameters as well as answer scientific questions that traditional microscopic techniques cannot. Specifically, we will visit a Greenland field site to determine whether or not microorganisms are motile within the brine-filled interior network of sea ice, and if they can be autonomously tracked using the instrument. Motility within the liquid phase of a frozen matrix has been hypothesized to explain how bacteria contribute to the biogeochemical signatures detected in ice, but observational

  1. Specific maltose derivatives modulate the swarming motility of nonswarming mutant and inhibit bacterial adhesion and biofilm formation by Pseudomonas aeruginosa.

    PubMed

    Shetye, Gauri S; Singh, Nischal; Jia, Changqing; Nguyen, Chan D K; Wang, Guirong; Luk, Yan-Yeung

    2014-07-07

    We have demonstrated that specific synthetic maltose derivatives activate the swarming motility of a Pseudomonas aeruginosa nonswarming mutant (rhlA) at low concentration, but inhibit it at high concentration. Although these molecules are not microbicidal, active maltose derivatives with bulky hydrocarbon groups inhibited bacterial adhesion, and exhibited biofilm inhibition and dispersion (IC50 ~20 μM and DC50 ~30 μM, respectively). Because the swarming motility of the rhlA mutant is abolished by the lack natural rhamnolipids, the swarming activation suggests that maltose derivatives are analogues of rhamnolipids. Together, these results suggest a new approach of controlling multiple bacterial activities (bacterial adhesion, biofilm formation, and swarming motility) by a set of disaccharide-based molecules.

  2. High-throughput design of microfluidics based on directed bacterial motility.

    PubMed

    Kaehr, Bryan; Shear, Jason B

    2009-09-21

    Use of motile cells as sensors and actuators in microfabricated devices requires precise design of interfaces between living and non-living components, a process that has relied on slow revision of device architectures as prototypes are sequentially evaluated and re-designed. In this report, we describe a microdesign and fabrication approach capable of iteratively refining three-dimensional bacterial interfaces in periods as short as 10 minutes, and demonstrate its use to drive fluid transport by harnessing flagellar motion. In this approach, multiphoton excitation is used to promote protein photocrosslinking in a direct-write procedure mediated by static and dynamic masking, with the resultant microstructures serving to capture motile bacteria from the surrounding fluidic environment. Reproducible steering and patterning of flagellated E. coli cells drive microfluidic currents capable of guiding micro-objects on predictable trajectories with velocities reaching 150 microm s(-1) and achieving bulk flow through microchannels. We show that bacteria can be dynamically immobilized at specified positions, an approach that frees such devices from limitations imposed by the functional lifetime of cells. These results provide a foundation for the development of sophisticated microfluidic devices powered by cells.

  3. Crystal structure analysis reveals Pseudomonas PilY1 as an essential calcium-dependent regulator of bacterial surface motility

    SciTech Connect

    Orans, Jillian; Johnson, Michael D.L.; Coggan, Kimberly A.; Sperlazza, Justin R.; Heiniger, Ryan W.; Wolfgang, Matthew C.; Redinbo, Matthew R.

    2010-09-21

    Several bacterial pathogens require the 'twitching' motility produced by filamentous type IV pili (T4P) to establish and maintain human infections. Two cytoplasmic ATPases function as an oscillatory motor that powers twitching motility via cycles of pilus extension and retraction. The regulation of this motor, however, has remained a mystery. We present the 2.1 {angstrom} resolution crystal structure of the Pseudomonas aeruginosa pilus-biogenesis factor PilY1, and identify a single site on this protein required for bacterial translocation. The structure reveals a modified {beta}-propeller fold and a distinct EF-hand-like calcium-binding site conserved in pathogens with retractile T4P. We show that preventing calcium binding by PilY1 using either an exogenous calcium chelator or mutation of a single residue disrupts Pseudomonas twitching motility by eliminating surface pili. In contrast, placing a lysine in this site to mimic the charge of a bound calcium interferes with motility in the opposite manner - by producing an abundance of nonfunctional surface pili. Our data indicate that calcium binding and release by the unique loop identified in the PilY1 crystal structure controls the opposing forces of pilus extension and retraction. Thus, PilY1 is an essential, calcium-dependent regulator of bacterial twitching motility.

  4. Crystal structure analysis reveals Pseudomonas PilY1 as an essential calcium-dependent regulator of bacterial surface motility

    PubMed Central

    Orans, Jillian; Johnson, Michael D. L.; Coggan, Kimberly A.; Sperlazza, Justin R.; Heiniger, Ryan W.; Wolfgang, Matthew C.; Redinbo, Matthew R.

    2010-01-01

    Several bacterial pathogens require the “twitching” motility produced by filamentous type IV pili (T4P) to establish and maintain human infections. Two cytoplasmic ATPases function as an oscillatory motor that powers twitching motility via cycles of pilus extension and retraction. The regulation of this motor, however, has remained a mystery. We present the 2.1 Å resolution crystal structure of the Pseudomonas aeruginosa pilus-biogenesis factor PilY1, and identify a single site on this protein required for bacterial translocation. The structure reveals a modified β-propeller fold and a distinct EF-hand-like calcium-binding site conserved in pathogens with retractile T4P. We show that preventing calcium binding by PilY1 using either an exogenous calcium chelator or mutation of a single residue disrupts Pseudomonas twitching motility by eliminating surface pili. In contrast, placing a lysine in this site to mimic the charge of a bound calcium interferes with motility in the opposite manner—by producing an abundance of nonfunctional surface pili. Our data indicate that calcium binding and release by the unique loop identified in the PilY1 crystal structure controls the opposing forces of pilus extension and retraction. Thus, PilY1 is an essential, calcium-dependent regulator of bacterial twitching motility. PMID:20080557

  5. Effects of zinc oxide nanoparticles on Kupffer cell phagosomal motility, bacterial clearance, and liver function

    PubMed Central

    Watson, Christa Y; Molina, Ramon M; Louzada, Andressa; Murdaugh, Kimberly M; Donaghey, Thomas C; Brain, Joseph D

    2015-01-01

    Background Zinc oxide engineered nanoparticles (ZnO ENPs) have potential as nanomedicines due to their inherent properties. Studies have described their pulmonary impact, but less is known about the consequences of ZnO ENP interactions with the liver. This study was designed to describe the effects of ZnO ENPs on the liver and Kupffer cells after intravenous (IV) administration. Materials and methods First, pharmacokinetic studies were conducted to determine the tissue distribution of neutron-activated 65ZnO ENPs post-IV injection in Wistar Han rats. Then, a noninvasive in vivo method to assess Kupffer cell phagosomal motility was employed using ferromagnetic iron particles and magnetometry. We also examined whether prior IV injection of ZnO ENPs altered Kupffer cell bactericidal activity on circulating Pseudomonas aeruginosa. Serum and liver tissues were collected to assess liver-injury biomarkers and histological changes, respectively. Results We found that the liver was the major site of initial uptake of 65ZnO ENPs. There was a time-dependent decrease in tissue levels of 65Zn in all organs examined, refecting particle dissolution. In vivo magnetometry showed a time-dependent and transient reduction in Kupffer cell phagosomal motility. Animals challenged with P. aeruginosa 24 hours post-ZnO ENP injection showed an initial (30 minutes) delay in vascular bacterial clearance. However, by 4 hours, IV-injected bacteria were cleared from the blood, liver, spleen, lungs, and kidneys. Seven days post-ZnO ENP injection, creatine phosphokinase and aspartate aminotransferase levels in serum were significantly increased. Histological evidence of hepatocyte damage and marginated neutrophils were observed in the liver. Conclusion Administration of ZnO ENPs transiently inhibited Kupffer cell phagosomal motility and later induced hepatocyte injury, but did not alter bacterial clearance from the blood or killing in the liver, spleen, lungs, or kidneys. Our data show that

  6. In vivo imaging and genetic analysis link bacterial motility and symbiosis in the zebrafish gut

    PubMed Central

    Rawls, John F.; Mahowald, Michael A.; Goodman, Andrew L.; Trent, Chad M.; Gordon, Jeffrey I.

    2007-01-01

    Complex microbial communities reside within the intestines of humans and other vertebrates. Remarkably little is known about how these microbial consortia are established in various locations within the gut, how members of these consortia behave within their dynamic ecosystems, or what microbial factors mediate mutually beneficial host–microbial interactions. Using a gnotobiotic zebrafish–Pseudomonas aeruginosa model, we show that the transparency of this vertebrate species, coupled with methods for raising these animals under germ-free conditions can be used to monitor microbial movement and localization within the intestine in vivo and in real time. Germ-free zebrafish colonized with isogenic P. aeruginosa strains containing deletions of genes related to motility and pathogenesis revealed that loss of flagellar function results in attenuation of evolutionarily conserved host innate immune responses but not conserved nutrient responses. These results demonstrate the utility of gnotobiotic zebrafish in defining the behavior and localization of bacteria within the living vertebrate gut, identifying bacterial genes that affect these processes, and assessing the impact of these genes on host–microbial interactions. PMID:17456593

  7. The contribution of cell-cell signaling and motility to bacterial biofilm formation

    PubMed Central

    Shrout, Joshua D.; Tolker-Nielsen, Tim; Givskov, Michael; Parsek, Matthew R.

    2011-01-01

    Many bacteria grow attached to a surface as biofilms. Several factors dictate biofilm formation, including responses by the colonizing bacteria to their environment. Here we review how bacteria use cell-cell signaling (also called quorum sensing) and motility during biofilm formation. Specifically, we describe quorum sensing and surface motility exhibited by the bacterium Pseudomonas aeruginosa, a ubiquitous environmental organism that acts as an opportunistic human pathogen in immunocompromised individuals. P. aeruginosa uses acyl-homoserine lactone signals during quorum sensing to synchronize gene expression important to the production of polysaccharides, rhamnolipid, and other virulence factors. Surface motility affects the assembly and architecture of biofilms, and some aspects of motility are also influenced by quorum sensing. While some genes and their function are specific to P. aeruginosa, many aspects of biofilm development can be used as a model system to understand how bacteria differentially colonize surfaces. PMID:22053126

  8. Bidirectional Bacterial Gliding Motility Powered by the Collective Transport of Cell Surface Proteins

    NASA Astrophysics Data System (ADS)

    Wada, Hirofumi; Nakane, Daisuke; Chen, Hsuan-Yi

    2013-12-01

    The gliding motility of Flavobacterium johnsoniae is driven by moving surface adhesive proteins. Recently, these motility components were observed to travel along a closed loop on the cell surface. The mechanism by which such moving surface adhesins give rise to cell motion remains unknown. On the basis of the unique motility properties of F. johnsoniae, we present a generic model for bidirectional motion of rigidly coupled adhesins, which are propelled in opposite directions. Using analytical and numerical methods, we demonstrate that, for a sufficiently large adhesin speed, bidirectional motion arises from spontaneous symmetry breaking. The model also predicts that, close to the bifurcation point, a weak asymmetry in the binding dynamics is sufficient to facilitate directed motility, indicating that the direction of motion could be sensitively regulated internally in response to inhomogeneity of the environment.

  9. Motility, chemotaxis and aerotaxis contribute to competitiveness during bacterial pellicle biofilm development

    PubMed Central

    Gallegos-Monterrosa, Ramses; Price-Whelan, Alexa; Kolter, Roberto; Dietrich, Lars E. P.; Kovács, Ákos T.

    2016-01-01

    Biofilm formation is a complex process involving various signaling pathways and changes in gene expression. Many of the sensory mechanisms and regulatory cascades involved have been defined for biofilms formed by diverse organisms attached to solid surfaces. By comparison, our knowledge of the basic mechanisms underlying the formation of biofilms at air-liquid interfaces, i.e. pellicles, is much less complete. In particular, the roles of flagella have been studied in multiple solid-surface biofilm models, but remain largely undefined for pellicles. In this work, we characterize the contributions of flagellum-based motility, chemotaxis and oxygen sensing to pellicle formation in the Gram-positive Bacillus subtilis. We confirm that flagellum-based motility is involved in, but is not absolutely essential for, B. subtilis pellicle formation. Further, we show that flagellum-based motility, chemotaxis, and oxygen sensing are important for successful competition during B. subtilis pellicle formation. We report that flagellum-based motility similarly contributes to pellicle formation and fitness in competition assays in the Gram-negative Pseudomonas aeruginosa. Time-lapse imaging of static liquid cultures demonstrates that in both B. subtilis and P. aeruginosa, a turbulent flow forms in the tube and a zone of clearing appears below the air-liquid interface just before the formation of the pellicle, but only in strains that have flagella. PMID:26122431

  10. Bacterial twitching motility is coordinated by a two-dimensional tug-of-war with directional memory

    NASA Astrophysics Data System (ADS)

    Marathe, Rahul; Meel, Claudia; Schmidt, Nora C.; Dewenter, Lena; Kurre, Rainer; Greune, Lilo; Alexander Schmidt, M.; Müller, Melanie J. I.; Lipowsky, Reinhard; Maier, Berenike; Klumpp, Stefan

    2014-05-01

    Type IV pili are ubiquitous bacterial motors that power surface motility. In peritrichously piliated species, it is unclear how multiple pili are coordinated to generate movement with directional persistence. Here we use a combined theoretical and experimental approach to test the hypothesis that multiple pili of Neisseria gonorrhoeae are coordinated through a tug-of-war. Based on force-dependent unbinding rates and pilus retraction speeds measured at the level of single pili, we build a tug-of-war model. Whereas the one-dimensional model robustly predicts persistent movement, the two-dimensional model requires a mechanism of directional memory provided by re-elongation of fully retracted pili and pilus bundling. Experimentally, we confirm memory in the form of bursts of pilus retractions. Bursts are seen even with bundling suppressed, indicating re-elongation from stable core complexes as the key mechanism of directional memory. Directional memory increases the surface range explored by motile bacteria and likely facilitates surface colonization.

  11. A bacterial extracellular DNA inhibits settling of motile progeny cells within a biofilm

    PubMed Central

    Berne, Cécile; Kysela, David T.; Brun, Yves V.

    2010-01-01

    In natural systems, bacteria form complex, surface-attached communities known as biofilms. This lifestyle presents numerous advantages compared to unattached or planktonic life, such as exchange of nutrients, protection from environmental stresses and increased tolerance to biocides. Despite such benefits, dispersal also plays an important role in escaping deteriorating environments and in successfully colonizing favorable, unoccupied habitat patches. The α-proteobacterium Caulobacter crescentus produces a motile swarmer cell and a sessile stalked cell at each cell division. We show here that C. crescentus extracellular DNA (eDNA) inhibits the ability of its motile cell type to settle in a biofilm. eDNA binds to the polar holdfast, an adhesive structure required for permanent surface attachment and biofilm formation, thereby inhibiting cell attachment. Since stalked cells associate tightly with the biofilm through their holdfast, we hypothesize that this novel mechanism acts on swarmer cells born in a biofilm, where eDNA can accumulate to a sufficient concentration to inhibit their ability to settle. By targeting a specific cell type in a biofilm, this mechanism modulates biofilm development and promotes dispersal without causing a potentially undesirable dissolution of the existing biofilm. PMID:20598083

  12. In the search of anisotropic biocompatible liquid environments for bacterial motility studies

    NASA Astrophysics Data System (ADS)

    Duchesne, Ismael; Galstian, Tigran V.; Rainville, Simon

    2014-10-01

    Several experimental approaches are explored to introduce the E. coli bacteria in a liquid anisotropic host. Fonctionalization of the bacterial surface is experimented with 2 different molecules. The 5CB is first used as host and it is shown that, while the bacteria survive at short term in such an environment, they aggregate into colonies. Water solution of the cromolyn sodium salt is also explored with success and the time stability of corresponding sandwich-like structures is characterized.

  13. Testing an agent-based model of bacterial cell motility: How nutrient concentration affects speed distribution

    NASA Astrophysics Data System (ADS)

    Garcia, V.; Birbaumer, M.; Schweitzer, F.

    2011-08-01

    We revisit a recently proposed agent-based model of active biological motion and compare its predictions with own experimental findings for the speed distribution of bacterial cells, Salmonella typhimurium. Agents move according to a stochastic dynamics and use energy stored in an internal depot for metabolism and active motion. We discuss different assumptions of how the conversion from internal to kinetic energy d( v) may depend on the actual speed, to conclude that d 2 v ξ with either ξ = 2 or 1 < ξ < 2 are promising hypotheses. To test these, we compare the model's prediction with the speed distribution of bacteria which were obtained in media of different nutrient concentration and at different times. We find that both hypotheses are in line with the experimental observations, with ξ between 1.67 and 2.0. Regarding the influence of a higher nutrient concentration, we conclude that the take-up of energy by bacterial cells is indeed increased. But this energy is not used to increase the speed, with 40 μm/s as the most probable value of the speed distribution, but is rather spend on metabolism and growth.

  14. The Bacterial Cytoskeleton Modulates Motility, Type 3 Secretion, and Colonization in Salmonella

    PubMed Central

    Bulmer, David M.; Kharraz, Lubna; Grant, Andrew J.; Dean, Paul; Morgan, Fiona J. E.; Karavolos, Michail H.; Doble, Anne C.; McGhie, Emma J.; Koronakis, Vassilis; Daniel, Richard A.; Mastroeni, Pietro; Anjam Khan, C. M.

    2012-01-01

    Although there have been great advances in our understanding of the bacterial cytoskeleton, major gaps remain in our knowledge of its importance to virulence. In this study we have explored the contribution of the bacterial cytoskeleton to the ability of Salmonella to express and assemble virulence factors and cause disease. The bacterial actin-like protein MreB polymerises into helical filaments and interacts with other cytoskeletal elements including MreC to control cell-shape. As mreB appears to be an essential gene, we have constructed a viable ΔmreC depletion mutant in Salmonella. Using a broad range of independent biochemical, fluorescence and phenotypic screens we provide evidence that the Salmonella pathogenicity island-1 type three secretion system (SPI1-T3SS) and flagella systems are down-regulated in the absence of MreC. In contrast the SPI-2 T3SS appears to remain functional. The phenotypes have been further validated using a chemical genetic approach to disrupt the functionality of MreB. Although the fitness of ΔmreC is reduced in vivo, we observed that this defect does not completely abrogate the ability of Salmonella to cause disease systemically. By forcing on expression of flagella and SPI-1 T3SS in trans with the master regulators FlhDC and HilA, it is clear that the cytoskeleton is dispensable for the assembly of these structures but essential for their expression. As two-component systems are involved in sensing and adapting to environmental and cell surface signals, we have constructed and screened a panel of such mutants and identified the sensor kinase RcsC as a key phenotypic regulator in ΔmreC. Further genetic analysis revealed the importance of the Rcs two-component system in modulating the expression of these virulence factors. Collectively, these results suggest that expression of virulence genes might be directly coordinated with cytoskeletal integrity, and this regulation is mediated by the two-component system sensor kinase Rcs

  15. Allelic variation in two distinct Pseudomonas syringae flagellin epitopes modulates the strength of plant immune responses but not bacterial motility

    PubMed Central

    Clarke, Christopher R.; Chinchilla, Delphine; Hind, Sarah R.; Taguchi, Fumiko; Miki, Ryuji; Ichinose, Yuki; Martin, Gregory B.; Leman, Scotland; Felix, Georg; Vinatzer, Boris A.

    2013-01-01

    Summary The bacterial flagellin (FliC) epitopes flg22 and flgII-28 are microbe-associated molecular patterns (MAMPs). While flg22 is recognized by many plant species via the pattern recognition receptor FLS2, neither the flgII-28 receptor nor the extent of flgII-28 recognition by different plant families is known.Here we tested the significance of flgII-28 as a MAMP and the importance of allelic diversity in flg22 and flgII-28 in plant–pathogen interactions using purified peptides and a Pseudomonas syringae ΔfliC mutant complemented with different fliC alleles.Plant genotype and allelic diversity in flg22 and flgII-28 were found to significantly affect the plant immune response but not bacterial motility. Recognition of flgII-28 is restricted to a number of Solanaceous species. While the flgII-28 peptide does not trigger any immune response in Arabidopsis, mutations in both flg22 and flgII-28 have FLS2-dependent effects on virulence. However, expression of a tomato allele of FLS2 does not confer to Nicotiana benthamiana the ability to detect flgII-28 and tomato plants silenced for FLS2 are not altered in flgII-28 recognition.Therefore, MAMP diversification is an effective pathogen virulence strategy and flgII-28 appears to be perceived by a yet unidentified receptor in the Solanaceae although it has an FLS2-dependent virulence effect in Arabidopsis. PMID:23865782

  16. Fur Represses Adhesion to, Invasion of, and Intracellular Bacterial Community Formation within Bladder Epithelial Cells and Motility in Uropathogenic Escherichia coli.

    PubMed

    Kurabayashi, Kumiko; Agata, Tomohiro; Asano, Hirofumi; Tomita, Haruyoshi; Hirakawa, Hidetada

    2016-11-01

    Uropathogenic Escherichia coli (UPEC) is a major pathogen that causes urinary tract infections (UTIs). This bacterium adheres to and invades the host cells in the bladder, where it forms biofilm-like polymicrobial structures termed intracellular bacterial communities (IBCs) that protect UPEC from antimicrobial agents and the host immune systems. Using genetic screening, we found that deletion of the fur gene, which encodes an iron-binding transcriptional repressor for iron uptake systems, elevated the expression of type I fimbriae and motility when UPEC was grown under iron-rich conditions, and it led to an increased number of UPEC cells adhering to and internalized in bladder epithelial cells. Consequently, the IBC colonies that the fur mutant formed in host cells were denser and larger than those formed by the wild-type parent strain. Fur is inactivated under iron-restricted conditions. When iron was depleted from the bacterial cultures, wild-type UPEC adhesion, invasion, and motility increased, similar to the case with the fur mutant. The purified Fur protein bound to regions upstream of fimA and flhD, which encode type I fimbriae and an activator of flagellar expression that contributes to motility, respectively. These results suggest that Fur is a repressor of fimA and flhD and that its repression is abolished under iron-depleted conditions. Based on our in vitro experiments, we conclude that UPEC adhesion, invasion, IBC formation, and motility are suppressed by Fur under iron-rich conditions but derepressed under iron-restricted conditions, such as in patients with UTIs.

  17. Immunity Provided by an Outer Membrane Vesicle Cholera Vaccine Is Due to O-Antigen-Specific Antibodies Inhibiting Bacterial Motility.

    PubMed

    Wang, Zhu; Lazinski, David W; Camilli, Andrew

    2017-01-01

    An outer membrane vesicle (OMV)-based cholera vaccine is highly efficacious in preventing intestinal colonization in the suckling mouse model. Immunity from OMVs comes from immunoglobulin (Ig), particularly IgG, in the milk of mucosally immunized dams. Anti-OMV IgG renders Vibrio cholerae organisms immotile, thus they pass through the small intestine without colonizing. However, the importance of motility inhibition for protection and the mechanism by which motility is inhibited remain unclear. By using both in vitro and in vivo experiments, we found that IgG inhibits motility by specifically binding to the O-antigen of V. cholerae We demonstrate that the bivalent structure of IgG, although not required for binding to the O-antigen, is required for motility inhibition. Finally, we show using competition assays in suckling mice that inhibition of motility appears to be responsible for most, if not all, of the protection engendered by OMV vaccination, thus providing insight into the mechanism of immune protection.

  18. Interaction of pathogenic bacteria with rabbit appendix M cells: bacterial motility is a key feature in vivo.

    PubMed

    Marchetti, Marta; Sirard, Jean Claude; Sansonetti, Philippe; Pringault, Eric; Kernéis, Sophie

    2004-05-01

    Rabbit appendix consists mainly of lymphoid follicles (LF) covered by M cells, the specialized antigen-sampling cells of the mucosal immune system, and surrounded by glandular epithelium. Until now, these M cells have been characterized morphologically and histologically by using cellular markers. Here, the adhesion and transport of pathogenic bacteria were investigated to assess the function of M cells of the appendix. We used the enteroinvasive motile Salmonella typhimurium and the rabbit enteropathogenic non-motile Escherichia coli RDEC-1, which are known to target specifically rabbit M cells of Peyer's patches (PPs). We found that S. typhimurium efficiently attached and was transported through appendix M cells in vivo. In contrast to S. typhimurium, RDEC-1 targeted M cells only ex vivo, when bacteria were allowed to have direct contact with the surface of the follicle. The difference in interaction of the two bacteria with appendix M cells led us to investigate whether this could be correlated with the lack of motility of RDEC-1. We used an aflagellate mutant of S. typhimurium and found that it had the same infection phenotype as RDEC-1. Gene complementation restored the efficiency of infection to that of S. typhimurium wild-type strain. In conclusion, we show that M cells of the appendix display features of the canonical M cells of PP, since they efficiently sample luminal pathogenic bacteria. However, due to the morphology of the appendix, motile bacteria appear to be more potent in their interactions with appendix M cells.

  19. Siderophore-Mediated Iron Acquisition Influences Motility and Is Required for Full Virulence of the Xylem-Dwelling Bacterial Phytopathogen Pantoea stewartii subsp. stewartii

    PubMed Central

    Burbank, Lindsey; Mohammadi, Mojtaba

    2014-01-01

    Iron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form. Pantoea stewartii subsp. stewartii, the causal agent of Stewart's wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by the iucABCD-iutA operon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations in iucA and iutA resulted in a decrease in surface-based motility that P. stewartii utilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility for P. stewartii. Furthermore, bacterial movement in planta is also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen. PMID:25326304

  20. Siderophore-mediated iron acquisition influences motility and is required for full virulence of the xylem-dwelling bacterial phytopathogen Pantoea stewartii subsp. stewartii.

    PubMed

    Burbank, Lindsey; Mohammadi, Mojtaba; Roper, M Caroline

    2015-01-01

    Iron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form. Pantoea stewartii subsp. stewartii, the causal agent of Stewart's wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by the iucABCD-iutA operon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations in iucA and iutA resulted in a decrease in surface-based motility that P. stewartii utilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility for P. stewartii. Furthermore, bacterial movement in planta is also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen.

  1. Small-Molecule Inhibitors of the Pseudaminic Acid Biosynthetic Pathway: Targeting Motility as a Key Bacterial Virulence Factor

    PubMed Central

    Ménard, Robert; Schoenhofen, Ian C.; Tao, Limei; Aubry, Annie; Bouchard, Patrice; Reid, Christopher W.; Lachance, Paule; Twine, Susan M.; Fulton, Kelly M.; Cui, Qizhi; Hogues, Hervé; Purisima, Enrico O.

    2014-01-01

    Helicobacter pylori is motile by means of polar flagella, and this motility has been shown to play a critical role in pathogenicity. The major structural flagellin proteins have been shown to be glycosylated with the nonulosonate sugar, pseudaminic acid (Pse). This glycan is unique to microorganisms, and the process of flagellin glycosylation is required for H. pylori flagellar assembly and consequent motility. As such, the Pse biosynthetic pathway offers considerable potential as an antivirulence drug target, especially since motility is required for H. pylori colonization and persistence in the host. This report describes screening the five Pse biosynthetic enzymes for small-molecule inhibitors using both high-throughput screening (HTS) and in silico (virtual screening [VS]) approaches. Using a 100,000-compound library, 1,773 hits that exhibited a 40% threshold inhibition at a 10 μM concentration were identified by HTS. In addition, VS efforts using a 1.6-million compound library directed at two pathway enzymes identified 80 hits, 4 of which exhibited reasonable inhibition at a 10 μM concentration in vitro. Further secondary screening which identified 320 unique molecular structures or validated hits was performed. Following kinetic studies and structure-activity relationship (SAR) analysis of selected inhibitors from our refined list of 320 compounds, we demonstrated that three inhibitors with 50% inhibitory concentrations (IC50s) of approximately 14 μM, which belonged to a distinct chemical cluster, were able to penetrate the Gram-negative cell membrane and prevent formation of flagella. PMID:25267679

  2. A structure activity-relationship study of the bacterial signal molecule HHQ reveals swarming motility inhibition in Bacillus atrophaeus.

    PubMed

    Reen, F Jerry; Shanahan, Rachel; Cano, Rafael; O'Gara, Fergal; McGlacken, Gerard P

    2015-05-21

    The sharp rise in antimicrobial resistance has been matched by a decline in the identification and clinical introduction of new classes of drugs to target microbial infections. Thus new approaches are being sought to counter the pending threat of a post-antibiotic era. In that context, the use of non-growth limiting small molecules, that target virulence behaviour in pathogens, has emerged as a solution with real clinical potential. We have previously shown that two signal molecules (HHQ and PQS) from the nosocomial pathogen Pseudomonas aeruginosa have modulatory activity towards other microorganisms. This current study involves the synthesis and evaluation of analogues of HHQ towards swarming and biofilm virulence behaviour in Bacillus atrophaeus, a soil bacterium and co-inhibitor with P. aeruginosa. Compounds with altered C6-C8 positions on the anthranilate-derived ring of HHQ, display a surprising degree of biological specificity, with certain candidates displaying complete motility inhibition. In contrast, anti-biofilm activity of the parent molecule was completely lost upon alteration at any position indicating a remarkable degree of specificity and delineation of phenotype.

  3. Self-organization of bacterial communities against environmental pH variation: Controlled chemotactic motility arranges cell population structures in biofilms

    PubMed Central

    Nakayama, Madoka; Shoji, Wataru

    2017-01-01

    As with many living organisms, bacteria often live on the surface of solids, such as foods, organisms, buildings and soil. Compared with dispersive behavior in liquid, bacteria on surface environment exhibit significantly restricted mobility. They have access to only limited resources and cannot be liberated from the changing environment. Accordingly, appropriate collective strategies are necessarily required for long-term growth and survival. However, in spite of our deepening knowledge of the structure and characteristics of individual cells, strategic self-organizing dynamics of their community is poorly understood and therefore not yet predictable. Here, we report a morphological change in Bacillus subtilis biofilms due to environmental pH variations, and present a mathematical model for the macroscopic spatio-temporal dynamics. We show that an environmental pH shift transforms colony morphology on hard agar media from notched ‘volcano-like’ to round and front-elevated ‘crater-like’. We discover that a pH-dependent dose-response relationship between nutritional resource level and quantitative bacterial motility at the population level plays a central role in the mechanism of the spatio-temporal cell population structure design in biofilms. PMID:28253348

  4. The new flagella-associated collagen-like proteins ClpB and ClpC of Bacillus amyloliquefaciens FZB42 are involved in bacterial motility.

    PubMed

    Zhao, Xia; Wang, Ruoyu; Shang, Qianhan; Hao, Haiting; Li, Yuyao; Zhang, Yubao; Guo, Zhihong; Wang, Yun; Xie, Zhongkui

    2016-03-01

    Collagen-like proteins (CLPs) share the distinctive Gly-X-Thr repeating amino acid sequence of animal collagens, and contain N- and C-terminal domain making a collagen-like structure in Bacillus amyloliquefaciens FZB42, a plant growth-promoting rhizobacterium. Our previous study demonstrated that CLPs play important roles in biofilm construction and adherence to the surfaces on plant roots. However, bacterial localization of the CLPs remains unclear. Here, disrupted strains on all four clp genes (clpA, clpB, clpC and clpD) shown fewer filament than wild-type bacteria in extracellular matrix under scanning electron microscope (SEM). Transmission electron microscopy (TEM) was used to observe the differences on filament which associated on the cell surface, then the CLPs mutation strains showed less flagella than the wild type. Immunogold labeling determined the location that ClpB and ClpC localized on the flagella surface. In addition, western blotting analysis of crude flagella extracts suggested that the ClpB and ClpC are associated to flagella as well. The mutation strains also reduced motility of swimming on the surface of soft agar medium and changed the architectural of microcolony biofilm edge. The study suggests that collagen-like protein ClpB and ClpC, as novel proteins, associated with flagella in B. amyloliquefaciens.

  5. Self-organization of bacterial communities against environmental pH variation: Controlled chemotactic motility arranges cell population structures in biofilms.

    PubMed

    Tasaki, Sohei; Nakayama, Madoka; Shoji, Wataru

    2017-01-01

    As with many living organisms, bacteria often live on the surface of solids, such as foods, organisms, buildings and soil. Compared with dispersive behavior in liquid, bacteria on surface environment exhibit significantly restricted mobility. They have access to only limited resources and cannot be liberated from the changing environment. Accordingly, appropriate collective strategies are necessarily required for long-term growth and survival. However, in spite of our deepening knowledge of the structure and characteristics of individual cells, strategic self-organizing dynamics of their community is poorly understood and therefore not yet predictable. Here, we report a morphological change in Bacillus subtilis biofilms due to environmental pH variations, and present a mathematical model for the macroscopic spatio-temporal dynamics. We show that an environmental pH shift transforms colony morphology on hard agar media from notched 'volcano-like' to round and front-elevated 'crater-like'. We discover that a pH-dependent dose-response relationship between nutritional resource level and quantitative bacterial motility at the population level plays a central role in the mechanism of the spatio-temporal cell population structure design in biofilms.

  6. The galU gene of Xanthomonas campestris pv. campestris is involved in bacterial attachment, cell motility, polysaccharide synthesis, virulence, and tolerance to various stresses.

    PubMed

    Liao, Chao-Tsai; Du, Shin-Chiao; Lo, Hsueh-Hsia; Hsiao, Yi-Min

    2014-10-01

    Uridine triphosphate (UTP)-glucose-1-phosphate uridylyltransferase (GalU; EC 2.7.7.9) is an enzyme that catalyzes the formation of uridine diphosphate (UDP)-glucose from UTP and glucose-1-phosphate. GalU is involved in virulence in a number of animal-pathogenic bacteria since its product, UDP-glucose, is indispensable for the biosynthesis of virulence factors such as lipopolysaccharide and exopolysaccharide. However, its function in Xanthomonas campestris pv. campestris, the phytopathogen that causes black rot in cruciferous plants, is unclear. Here, we characterized a galU mutant of X. campestris pv. campestris and showed that the X. campestris pv. campestris galU mutant resulted in a reduction in virulence on the host cabbage. We also demonstrated that galU is involved in bacterial attachment, cell motility, and polysaccharide synthesis. Furthermore, the galU mutant showed increased sensitivity to various stress conditions including copper sulfate, hydrogen peroxide, and sodium dodecyl sulfate. In addition, mutation of galU impairs the expression of the flagellin gene fliC as well as the attachment-related genes xadA, fhaC, and yapH. In conclusion, our results indicate involvement of galU in the virulence factor production and pathogenicity in X. campestris pv. campestris, and a role for galU in stress tolerance of this crucifer pathogen.

  7. PilY1 Promotes Legionella pneumophila Infection of Human Lung Tissue Explants and Contributes to Bacterial Adhesion, Host Cell Invasion, and Twitching Motility

    PubMed Central

    Hoppe, Julia; Ünal, Can M.; Thiem, Stefanie; Grimpe, Louisa; Goldmann, Torsten; Gaßler, Nikolaus; Richter, Matthias; Shevchuk, Olga; Steinert, Michael

    2017-01-01

    Legionnaires' disease is an acute fibrinopurulent pneumonia. During infection Legionella pneumophila adheres to the alveolar lining and replicates intracellularly within recruited macrophages. Here we provide a sequence and domain composition analysis of the L. pneumophila PilY1 protein, which has a high homology to PilY1 of Pseudomonas aeruginosa. PilY1 proteins of both pathogens contain a von Willebrand factor A (vWFa) and a C-terminal PilY domain. Using cellular fractionation, we assigned the L. pneumophila PilY1 as an outer membrane protein that is only expressed during the transmissive stationary growth phase. PilY1 contributes to infection of human lung tissue explants (HLTEs). A detailed analysis using THP-1 macrophages and A549 lung epithelial cells revealed that this contribution is due to multiple effects depending on host cell type. Deletion of PilY1 resulted in a lower replication rate in THP-1 macrophages but not in A549 cells. Further on, adhesion to THP-1 macrophages and A549 epithelial cells was decreased. Additionally, the invasion into non-phagocytic A549 epithelial cells was drastically reduced when PilY1 was absent. Complementation variants of a PilY1-negative mutant revealed that the C-terminal PilY domain is essential for restoring the wild type phenotype in adhesion, while the putatively mechanosensitive vWFa domain facilitates invasion into non-phagocytic cells. Since PilY1 also promotes twitching motility of L. pneumophila, we discuss the putative contribution of this newly described virulence factor for bacterial dissemination within infected lung tissue. PMID:28326293

  8. Learn About GI Motility

    MedlinePlus

    ... Disorders of the Large Intestine Disorders of the Pelvic Floor Motility Testing Personal Stories Contact About GI Motility ... Disorders of the Large Intestine Disorders of the Pelvic Floor Motility Testing Personal Stories Contact About GI Motility ...

  9. About GI Motility

    MedlinePlus

    ... Disorders of the Large Intestine Disorders of the Pelvic Floor Motility Testing Personal Stories Contact About GI Motility ... Disorders of the Large Intestine Disorders of the Pelvic Floor Motility Testing Personal Stories Contact About GI Motility ...

  10. Sodium houttuyfonate, a potential phytoanticipin derivative of antibacterial agent, inhibits bacterial attachment and pyocyanine secretion of Pseudomonas aeruginosa by attenuating flagella-mediated swimming motility.

    PubMed

    Shao, Jing; Cheng, Huijuan; Wang, Changzhong; Wu, Daqiang; Zhu, Xiaoli; Zhu, Lingling; Sun, Zhenxin

    2013-12-01

    Pseudomonas aeruginosa is a well-known clinical pathogen for its recalcitrant infection caused by biofilm formation which are initiated by flagella-mediated attachment. Sodium houttuyfonate (SH) is a natural phytoanticipin derivative of houttuynin and has anti-pathogenic effect on P. aeruginosa biofilm formation. In this paper, when using 1/2 × MIC SH, the diameter of P. aeruginosa swimming motility was sharply shortened to 36 % in 24 h incubation, and the fold changes of fliC required for swimming motility was 0.36 in 24 h cultivation, the adherence inhibition accounted for about 46 %, and the pyocyanin production decreased to 47 % after 1-day treatment and 56 % after 3-day treatment with obvious visual changes from dark green to light green, compared with the negative control. With the help of mass spectra and scanning electronic microscope, 1/2 × MIC SH was further testified to be enough to eradicate flagella and inhibit pyocyanin secretion of P. aeruginosa. The results do not only re-affirm the close interplay of attachment and virulence (i.e. swimming motility and pyocyanin), but also unravel the potential mechanism of SH on anti-biofilm of P. aeruginosa.

  11. Strigolactones in the Rhizobium-legume symbiosis: Stimulatory effect on bacterial surface motility and down-regulation of their levels in nodulated plants.

    PubMed

    Peláez-Vico, María A; Bernabéu-Roda, Lydia; Kohlen, Wouter; Soto, María J; López-Ráez, Juan A

    2016-04-01

    Strigolactones (SLs) are multifunctional molecules acting as modulators of plant responses under nutrient deficient conditions. One of the roles of SLs is to promote beneficial association with arbuscular mycorrhizal (AM) fungi belowground under such stress conditions, mainly phosphorus shortage. Recently, a role of SLs in the Rhizobium-legume symbiosis has been also described. While SLs' function in AM symbiosis is well established, their role in the Rhizobium-legume interaction is still emerging. Recently, SLs have been suggested to stimulate surface motility of rhizobia, opening the possibility that they could also act as molecular cues. The possible effect of SLs in the motility in the alfalfa symbiont Sinorhizobium meliloti was investigated, showing that the synthetic SL analogue GR24 stimulates swarming motility in S. meliloti in a dose-dependent manner. On the other hand, it is known that SL production is regulated by nutrient deficient conditions and by AM symbiosis. Using the model alfalfa-S. meliloti, the impact of phosphorus and nitrogen deficiency, as well as of nodulation on SL production was also assessed. The results showed that phosphorus starvation promoted SL biosynthesis, which was abolished by nitrogen deficiency. In addition, a negative effect of nodulation on SL levels was detected, suggesting a conserved mechanism of SL regulation upon symbiosis establishment.

  12. Microgravity, bacteria, and the influence of motility

    NASA Astrophysics Data System (ADS)

    Benoit, Michael R.; Klaus, David M.

    Space microbiology studies date back to the 1960s, with most investigations reporting that increased bacterial populations occur in flight compared to ground controls. Several exceptions to these findings, however, have created controversy and complicated explanations of how, or whether, microgravity affects microorganisms. Upon closer examination of the literature, we identified a trend relating cell motility to experimental outcome. Related studies conducted in microgravity analog devices, such as the clinostat or rotating wall vessel bioreactor, further corroborate this trend. We review the literature regarding bacterial growth experiments conducted in space (and using microgravity analogs) and analyze the influence of bacterial motility.

  13. Polymeric-based particulate systems for delivery of therapeutic proteins.

    PubMed

    Akash, Muhammad Sajid Hamid; Rehman, Kanwal; Chen, Shuqing

    2016-01-01

    Polymeric-based particulate systems have been intensively developed to increase the short biological half-life and prevent enzymatic degradation of therapeutic proteins. These techniques demonstrate the useful characteristics for the delivery of therapeutic proteins and peptides to the targeted site of application and prevent the interaction of encapsulated drug with the normal cells. In this article, we have described the in depth of different pharmaceutical-based techniques that are currently being practiced for efficient delivery of therapeutic proteins and peptides. A comprehensive English literature was searched using different electronic search databases including PubMed, Science Direct, Web of Science, google scholar and library search. Different search terms and advanced search were made by combining all the search fields in abstract, keywords and/or titles. Findings of various studies that have been discussed in this article clearly indicate that polymeric-based techniques can significantly increase the therapeutic potentials of incorporated proteins with no known toxic effects. These techniques have shown to maintain the stability and retain biological activity of protein therapeutics. Hence it can be suggested that pharmaceutical-based techniques are promising drug carriers for efficient delivery of therapeutic proteins.

  14. Modulation of Membrane Influx and Efflux in Escherichia coli Sequence Type 131 Has an Impact on Bacterial Motility, Biofilm Formation, and Virulence in a Caenorhabditis elegans Model

    PubMed Central

    Pantel, Alix; Dunyach-Remy, Catherine; Ngba Essebe, Christelle; Mesureur, Jennifer; Sotto, Albert; Nicolas-Chanoine, Marie-Hélène

    2016-01-01

    Energy-dependent efflux overexpression and altered outer membrane permeability (influx) can promote multidrug resistance (MDR). The present study clarifies the regulatory pathways that control membrane permeability in the pandemic clone Escherichia coli sequence type 131 (ST131) and evaluates the impact of efflux and influx modulations on biofilm formation, motility, and virulence in the Caenorhabditis elegans model. Mutants of two uropathogenic E. coli (UPEC) strains, MECB5 (ST131; H30-Rx) and CFT073 (ST73), as well as a fecal strain, S250 (ST131; H22), were in vitro selected using continuous subculture in subinhibitory concentrations of ertapenem (ETP), chloramphenicol (CMP), and cefoxitin (FOX). Mutations in genes known to control permeability were shown for the two UPEC strains: MECB5-FOX (deletion of 127 bp in marR; deletion of 1 bp and insertion of an IS1 element in acrR) and CFT073-CMP (a 1-bp deletion causing a premature stop in marR). We also demonstrated that efflux phenotypes in the mutants selected with CMP and FOX were related to the AcrAB-TolC pump, but also to other efflux systems. Alteration of membrane permeability, caused by underexpression of the two major porins, OmpF and OmpC, was shown in MECB5-ETP and mutants selected with FOX. Lastly, our findings suggest that efflux pump-overproducing isolates (CMP mutants) pose a serious threat in terms of virulence (significant reduction in worm median survival) and host colonization. Lack of porins (ETP and FOX mutants) led to a high level of antibiotic resistance in an H30-Rx subclone. Nevertheless, this adaptation created a physiological disadvantage (decreased motility and ability to form biofilm) associated with a low potential for virulence. PMID:26926643

  15. Spirochete motility and morpholgy

    NASA Astrophysics Data System (ADS)

    Charon, Nyles

    2004-03-01

    Spirochetes have a unique structure, and as a result their motility is different from that of other bacteria. These organisms can swim in a highly viscous, gel-like medium, such as that found in connective tissue, that inhibits the motility of most other bacteria. In spirochetes, the organelles for motility, the periplasmic flagella, reside inside the cell within the periplasmic space. A given periplasmic flagellum is attached only at one end of the cell, and depending on the species, may or may not overlap in the center of the cell. The number of periplasmic flagella varies from species to species. These structures have been shown to be directly involved in motility and function by rotating within the periplasmic space (1). The present talk focuses on the spirochete that causes Lyme disease, Borrelia burgdorferi. In many bacterial species, cell shape is usually dictated by the peptidoyglycan layer of the cell wall. In the first part of the talk, results will be presented that the morphology of B. burgdorferi is the result of a complex interaction between the cell cylinder and the internal periplasmic flagella resulting in a cell with a flat-wave morphology. Backward moving, propagating waves enable these bacteria to swim and translate in a given direction. Using targeted mutagenesis, we inactivated the gene encoding the major periplasmic flagellar filament protein FlaB. The resulting flaB mutants not only were non-motile, but were rod-shaped (2). Western blot analysis indicated that flaB was no longer synthesized, and electron microscopy revealed that the mutants were completely deficient in periplasmic flagella. Our results indicate that the periplasmic flagella of B. burgdorferi have a skeletal function. These organelles dynamically interact with the rod-shaped cell cylinder to enable the cell to swim, and to confer in part its flat-wave morphology The latter part of the talk concerns the basis for asymmetrical rotation of the periplasmic flagella of B

  16. High motility reduces grazing mortality of planktonic bacteria.

    PubMed

    Matz, Carsten; Jürgens, Klaus

    2005-02-01

    We tested the impact of bacterial swimming speed on the survival of planktonic bacteria in the presence of protozoan grazers. Grazing experiments with three common bacterivorous nanoflagellates revealed low clearance rates for highly motile bacteria. High-resolution video microscopy demonstrated that the number of predator-prey contacts increased with bacterial swimming speed, but ingestion rates dropped at speeds of >25 microm s(-1) as a result of handling problems with highly motile cells. Comparative studies of a moderately motile strain (<25 microm s(-1)) and a highly motile strain (>45 microm s(-1)) further revealed changes in the bacterial swimming speed distribution due to speed-selective flagellate grazing. Better long-term survival of the highly motile strain was indicated by fourfold-higher bacterial numbers in the presence of grazing compared to the moderately motile strain. Putative constraints of maintaining high swimming speeds were tested at high growth rates and under starvation with the following results: (i) for two out of three strains increased growth rate resulted in larger and slower bacterial cells, and (ii) starved cells became smaller but maintained their swimming speeds. Combined data sets for bacterial swimming speed and cell size revealed highest grazing losses for moderately motile bacteria with a cell size between 0.2 and 0.4 microm(3). Grazing mortality was lowest for cells of >0.5 microm(3) and small, highly motile bacteria. Survival efficiencies of >95% for the ultramicrobacterial isolate CP-1 (< or =0.1 microm(3), >50 microm s(-1)) illustrated the combined protective action of small cell size and high motility. Our findings suggest that motility has an important adaptive function in the survival of planktonic bacteria during protozoan grazing.

  17. Response of a Motile/Non-Motile Escherichia coli Front to Hydrodynamic excitations

    NASA Astrophysics Data System (ADS)

    Baabour, Magali; Douarche, Carine; Salin, Dominique

    2014-11-01

    In a recent study (Douarche et al. PRL 102, 198101 (2009)), it has been shown that the motility of Escherichia coli (E. coli) is highly correlated to the oxygen level in a minimal medium: bacteria swim as long as they are provided with oxygen but reversibly transit to a non-motile state when they lack of it. Hence, when oxygen diffuses into an anaerobic sample of non-motile bacteria, a propagating front delineates a region of motile bacteria where oxygen is present from a region of non-motile ones where the oxygen is still not present. To study the response of this front to hydrodynamics excitation, we use the same fluorescent E. coli bacterial solution in rectangular cross section glass cells open to air (oxygen) at one inlet. After bacteria have consumed the oxygen of the solution, the presence of the oxygen only at the open edge of the sample leads to the formation of an analogous stationary front between motile and non-motile bacteria. We follow the response of this front to hydrodynamics flows such as an oscillating Poiseuille flow or natural convection. We analyze both the macroscopic behavior (shape and width) of the front as well as the microscopic displacements of individual bacteria. The dispersive behavior of this bacterial front is compared to the one of equivalent. Collaboration between Laboratories FAST and LPS, Univ Paris Sud and CNRS.

  18. Methods for fabricating microarrays of motile bacteria.

    PubMed

    Rozhok, Sergey; Shen, Clifton K-F; Littler, Pey-Lih H; Fan, Zhifang; Liu, Chang; Mirkin, Chad A; Holz, Richard C

    2005-04-01

    Motile bacterial cell microarrays were fabricated by attaching Escherichia coli K-12 cells onto predesigned 16-mercaptohexadecanoic acid patterned microarrays, which were covalently functionalized with E. coli antibodies or poly-L-lysine. By utilizing 11-mercaptoundecyl-penta(ethylene glycol) or 11-mercapto-1-undecanol as passivating molecules, nonspecific binding of E. coli was significantly reduced. Microcontact printing and dip-pen nanolithography were used to prepare microarrays for bacterial adhesion, which was studied by optical fluorescence and atomic force microscopy. These data indicate that single motile E. coli can be attached to predesigned line or dot features and binding can occur via the cell body or the flagella of bacteria. Adherent bacteria are viable (remain alive and motile after adhesion to patterned surface features) for more than four hours. Individual motile bacterial cells can be placed onto predesigned surface features that are at least 1.3 microm in diameter or larger. The importance of controlling the adhesion of single bacterial cell to a surface is discussed with regard to biomotor design.

  19. Statistical physical models of cellular motility

    NASA Astrophysics Data System (ADS)

    Banigan, Edward J.

    Cellular motility is required for a wide range of biological behaviors and functions, and the topic poses a number of interesting physical questions. In this work, we construct and analyze models of various aspects of cellular motility using tools and ideas from statistical physics. We begin with a Brownian dynamics model for actin-polymerization-driven motility, which is responsible for cell crawling and "rocketing" motility of pathogens. Within this model, we explore the robustness of self-diffusiophoresis, which is a general mechanism of motility. Using this mechanism, an object such as a cell catalyzes a reaction that generates a steady-state concentration gradient that propels the object in a particular direction. We then apply these ideas to a model for depolymerization-driven motility during bacterial chromosome segregation. We find that depolymerization and protein-protein binding interactions alone are sufficient to robustly pull a chromosome, even against large loads. Next, we investigate how forces and kinetics interact during eukaryotic mitosis with a many-microtubule model. Microtubules exert forces on chromosomes, but since individual microtubules grow and shrink in a force-dependent way, these forces lead to bistable collective microtubule dynamics, which provides a mechanism for chromosome oscillations and microtubule-based tension sensing. Finally, we explore kinematic aspects of cell motility in the context of the immune system. We develop quantitative methods for analyzing cell migration statistics collected during imaging experiments. We find that during chronic infection in the brain, T cells run and pause stochastically, following the statistics of a generalized Levy walk. These statistics may contribute to immune function by mimicking an evolutionarily conserved efficient search strategy. Additionally, we find that naive T cells migrating in lymph nodes also obey non-Gaussian statistics. Altogether, our work demonstrates how physical

  20. Characterization of swarming motility in Citrobacter freundii.

    PubMed

    Cong, Yanguang; Wang, Jing; Chen, Zhijin; Xiong, Kun; Xu, Qiwang; Hu, Fuquan

    2011-04-01

    Bacterial swarming motility is a flagella-dependent translocation on the surface environment. It has received extensive attention as a population behavior involving numerous genes. Here, we report that Citrobacter freundii, an opportunistic pathogen, exhibits swarming movement on a solid medium surface with appropriate agar concentration. The swarming behavior of C. freundii was described in detail. Insertional mutagenesis with transposon Mini-Tn5 was carried out to discover genetic determinants related to the swarming of C. freundii. A number of swarming genes were identified, among which flhD, motA, motB, wzx, rfaL, rfaJ, rfbX, rfaG, rcsD, rcsC, gshB, fabF, dam, pgi, and rssB have been characterized previously in other species. In mutants related to lipopolysaccharide synthesis and RcsCDB signal system, a propensity to form poorly motile bacterial aggregates on the agar surface was observed. The aggregates hampered bacterial surface migration. In several mutants, the insertion sites were identified to be in the ORF of yqhC, yeeZ, CKO_03941, glgC, and ttrA, which have never been shown to be involved in swarming. Our results revealed several novel characteristics of swarming motility in C. freundii which are worthy of further study.

  1. Evolutionary aspects of collective motility in pathogenic bacteria

    NASA Astrophysics Data System (ADS)

    Deforet, Maxime; Xavier, Joao

    Pseudomonas aeruginosa is a pathogenic bacteria that can use its single polar flagellum to swim through liquids. It can move collectively over semisolid surfaces, a behavior called swarming. It can also settle and form surface-attached communities called biofilms that protect them from antibiotics. The transition from single motility (swimming) to collective motility (swarming) is biologically relevant as it enables exploring environments that a single bacterium cannot explore on its own. It is also clinically relevant since swarming and biofilm formation are thought to be antagonistic. We investigate the mechanisms of bacterial collective motility using a multidisciplinary approach that combines mathematical modeling, quantitative experiments, and microbial genetics. We aim to identify how these mechanisms may evolve under the selective pressure of population expansion, and consequently reinforce or hinder collective motility. In particular, we clarify the role of growth rate and motility in invasive populations.

  2. Bacterial rheotaxis.

    PubMed

    Marcos; Fu, Henry C; Powers, Thomas R; Stocker, Roman

    2012-03-27

    The motility of organisms is often directed in response to environmental stimuli. Rheotaxis is the directed movement resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates, and spermatozoa. Using carefully controlled microfluidic flows, we show that rheotaxis also occurs in bacteria. Excellent quantitative agreement between experiments with Bacillus subtilis and a mathematical model reveals that bacterial rheotaxis is a purely physical phenomenon, in contrast to fish rheotaxis but in the same way as sperm rheotaxis. This previously unrecognized bacterial taxis results from a subtle interplay between velocity gradients and the helical shape of flagella, which together generate a torque that alters a bacterium's swimming direction. Because this torque is independent of the presence of a nearby surface, bacterial rheotaxis is not limited to the immediate neighborhood of liquid-solid interfaces, but also takes place in the bulk fluid. We predict that rheotaxis occurs in a wide range of bacterial habitats, from the natural environment to the human body, and can interfere with chemotaxis, suggesting that the fitness benefit conferred by bacterial motility may be sharply reduced in some hydrodynamic conditions.

  3. Sperm Motility in Flow

    NASA Astrophysics Data System (ADS)

    Guasto, Jeffrey; Juarez, Gabriel; Stocker, Roman

    2012-11-01

    A wide variety of plants and animals reproduce sexually by releasing motile sperm that seek out a conspecific egg, for example in the reproductive tract for mammals or in the water column for externally fertilizing organisms. Sperm are aided in their quest by chemical cues, but must also contend with hydrodynamic forces, resulting from laminar flows in reproductive tracts or turbulence in aquatic habitats. To understand how velocity gradients affect motility, we subjected swimming sperm to a range of highly-controlled straining flows using a cross-flow microfluidic device. The motion of the cell body and flagellum were captured through high-speed video microscopy. The effects of flow on swimming are twofold. For moderate velocity gradients, flow simply advects and reorients cells, quenching their ability to cross streamlines. For high velocity gradients, fluid stresses hinder the internal bending of the flagellum, directly inhibiting motility. The transition between the two regimes is governed by the Sperm number, which compares the external viscous stresses with the internal elastic stresses. Ultimately, unraveling the role of flow in sperm motility will lead to a better understanding of population dynamics among aquatic organisms and infertility problems in humans.

  4. Soft micromachines with programmable motility and morphology.

    PubMed

    Huang, Hen-Wei; Sakar, Mahmut Selman; Petruska, Andrew J; Pané, Salvador; Nelson, Bradley J

    2016-07-22

    Nature provides a wide range of inspiration for building mobile micromachines that can navigate through confined heterogenous environments and perform minimally invasive environmental and biomedical operations. For example, microstructures fabricated in the form of bacterial or eukaryotic flagella can act as artificial microswimmers. Due to limitations in their design and material properties, these simple micromachines lack multifunctionality, effective addressability and manoeuvrability in complex environments. Here we develop an origami-inspired rapid prototyping process for building self-folding, magnetically powered micromachines with complex body plans, reconfigurable shape and controllable motility. Selective reprogramming of the mechanical design and magnetic anisotropy of body parts dynamically modulates the swimming characteristics of the micromachines. We find that tail and body morphologies together determine swimming efficiency and, unlike for rigid swimmers, the choice of magnetic field can subtly change the motility of soft microswimmers.

  5. Soft micromachines with programmable motility and morphology

    NASA Astrophysics Data System (ADS)

    Huang, Hen-Wei; Sakar, Mahmut Selman; Petruska, Andrew J.; Pané, Salvador; Nelson, Bradley J.

    2016-07-01

    Nature provides a wide range of inspiration for building mobile micromachines that can navigate through confined heterogenous environments and perform minimally invasive environmental and biomedical operations. For example, microstructures fabricated in the form of bacterial or eukaryotic flagella can act as artificial microswimmers. Due to limitations in their design and material properties, these simple micromachines lack multifunctionality, effective addressability and manoeuvrability in complex environments. Here we develop an origami-inspired rapid prototyping process for building self-folding, magnetically powered micromachines with complex body plans, reconfigurable shape and controllable motility. Selective reprogramming of the mechanical design and magnetic anisotropy of body parts dynamically modulates the swimming characteristics of the micromachines. We find that tail and body morphologies together determine swimming efficiency and, unlike for rigid swimmers, the choice of magnetic field can subtly change the motility of soft microswimmers.

  6. Bacterial Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Lauga, Eric

    2016-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells, yet they represent the bulk of the world's biomass and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micrometer scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically complex environments. Using hydrodynamics as an organizing framework, I review the biomechanics of bacterial motility and look ahead to future challenges.

  7. Motility of Mollicutes

    NASA Astrophysics Data System (ADS)

    Wolgemuth, Charles; Igoshin, Oleg; Oster, George

    2003-03-01

    Recent experiments show that the conformation of filament proteins play a role in the motility and morphology of many different types of bacteria. Conformational changes in the protein subunits may produce forces to drive propulsion and cell division. Here we present a molecular mechanism by which these forces can drive cell motion. Coupling of a biochemical cycle, such as ATP hydrolysis, to the dynamics of elastic filaments enable elastic filaments to propagate deformations that generate propulsive forces. We demonstrate this possibility for two classes of wall-less bacteria called mollicutes: the swimming of helical shaped Spiroplasma, and the gliding motility of Mycoplasma. Similar mechanisms may explain the locomotion of other prokaryotes, including the swimming of Synechococcus and the gliding of some myxobacteria.

  8. Modeling collective cell motility

    NASA Astrophysics Data System (ADS)

    Rappel, Wouter-Jan

    Eukaryotic cells often move in groups, a critical aspect of many biological and medical processes including wound healing, morphogenesis and cancer metastasis. Modeling can provide useful insights into the fundamental mechanisms of collective cell motility. Constructing models that incorporate the physical properties of the cells, however, is challenging. Here, I discuss our efforts to build a comprehensive cell motility model that includes cell membrane properties, cell-substrate interactions, cell polarity, and cell-cell interaction. The model will be applied to a variety of systems, including motion on micropatterned substrates and the migration of border cells in Drosophila. This work was supported by NIH Grant No. P01 GM078586 and NSF Grant No. 1068869.

  9. NCAM regulates cell motility.

    PubMed

    Prag, Søren; Lepekhin, Eugene A; Kolkova, Kateryna; Hartmann-Petersen, Rasmus; Kawa, Anna; Walmod, Peter S; Belman, Vadym; Gallagher, Helen C; Berezin, Vladimir; Bock, Elisabeth; Pedersen, Nina

    2002-01-15

    Cell migration is required during development of the nervous system. The regulatory mechanisms for this process, however, are poorly elucidated. We show here that expression of or exposure to the neural cell adhesion molecule (NCAM) strongly affected the motile behaviour of glioma cells independently of homophilic NCAM interactions. Expression of the transmembrane 140 kDa isoform of NCAM (NCAM-140) caused a significant reduction in cellular motility, probably through interference with factors regulating cellular attachment, as NCAM-140-expressing cells exhibited a decreased attachment to a fibronectin substratum compared with NCAM-negative cells. Ectopic expression of the cytoplasmic part of NCAM-140 also inhibited cell motility, presumably via the non-receptor tyrosine kinase p59(fyn) with which NCAM-140 interacts. Furthermore, we showed that the extracellular part of NCAM acted as a paracrine inhibitor of NCAM-negative cell locomotion through a heterophilic interaction with a cell-surface receptor. As we showed that the two N-terminal immunoglobulin modules of NCAM, which are known to bind to heparin, were responsible for this inhibition, we presume that this receptor is a heparan sulfate proteoglycan. A model for the inhibitory effect of NCAM is proposed, which involves competition between NCAM and extracellular components for the binding to membrane-associated heparan sulfate proteoglycan.

  10. Motility of Mycoplasma pneumoniae.

    PubMed Central

    Radestock, U; Bredt, W

    1977-01-01

    Cell of Mycoplasma pneumoniae FH gliding on a glass surface in liquid medium were examined by microscopic observation and quantitatively by microcinematography (30 frames per min). Comparisons were made only within the individual experiments. The cells moved in an irregular pattern with numerous narrow bends and circles. They never changed their leading end. The average speed (without pauses) was relatively constant between o.2 and 0.5 mum/s. The maximum speed was about 1.5 to 2.0 mum/s. The movements were interrupted by resting periods of different lengths and frequency. Temperature, viscosity, pH, and the presence of yeast extract in the medium influenced the motility significantly; changes in glucose, calcium ions, and serum content were less effective. The movements were affected by iodoacetate, p-mercuribenzoate, and mitomycin C at inhibitory or subinhibitory concentrations. Sodium fluoride, sodium cyanide, dinitrophenol, chloramphenicol, puromycin, cholchicin, and cytochalasin B at minimal inhibitory concentrations did not affect motility. The movements were effectively inhibited by anti-M. pneumoniae antiserum. Studies with absorbed antiserum suggested that the surface components involved in motility are heat labile. The gliding of M. pneumoniae cells required an intact energy metabolism and the proteins involved seemed to have a low turnover. Images PMID:14925

  11. Motility and peristaltic flow in maintaining microbiome populations

    NASA Astrophysics Data System (ADS)

    Mirbagheri, Seyed Amir; Fu, Henry C.

    2016-11-01

    Bacteria are an important component of the microbiome in the digestive tract, and must be able to maintain their population despite the fact that the contents of the intestines are constantly flowing towards evacuation. Many bacteria accomplish this by colonizing the surfaces of the intestines where flows diminish, but some species live in the lumen. We attempt to address whether swimming motility of these species plays an important role in maintaining bacterial population in the face of peristaltic pumping out of the intestine. Using a two-dimensional model of peristaltic flows induced by small-amplitude traveling waves we examine the Lagrangian trajectories of passive bacteria as well as motile bacteria, which are treated as Brownian particles undergoing enhanced diffusion due to the bacteria's run-and-tumble motility. We examine how the densities of growing populations of bacteria depend on the combination of motility and peristaltic flow.

  12. Correlating single cell motility with population growth dynamics for flagellated bacteria.

    PubMed

    Arora, Sucheta; Bhat, Vidya; Mittal, Aditya

    2007-08-15

    Many bacteria used for biotechnological applications are naturally motile. Their "bio-nanopropeller" driven movement allows searching for better environments in a process called chemotaxis. Since bacteria are extremely small in size compared to the bulk fluid volumes in bioreactors, single cell motility is not considered to influence bioreactor operations. However, with increasing interest in localized fluid flow inside reactors, it is important to ask whether individual motility characteristics of bacteria are important in bioreactor operations. The first step in this direction is to try to correlate single cell measurements with population data of motile bacteria in a bioreactor. Thus, we observed the motility behavior of individual bacterial cells, using video microscopy with 33 ms time resolution, as a function of population growth dynamics of batch cultures in shake flasks. While observing the motility behavior of the most intensively studied bacteria, Escherichia coli, we find that overall bacterial motility decreases with progression of the growth curve. Remarkably, this is due to a decrease in a specific motility behavior called "running". Our results not only have direct implications on biofilm formations, but also provide a new direction in bioprocess design research highlighting the role of individual bacterial cell motility as an important parameter.

  13. Actin-based motility propelled by molecular motors

    NASA Astrophysics Data System (ADS)

    Upadyayula, Sai Pramod; Rangarajan, Murali

    2012-09-01

    Actin-based motility of Listeria monocytogenes propelled by filament end-tracking molecular motors has been simulated. Such systems may act as potential nanoscale actuators and shuttles useful in sorting and sensing biomolecules. Filaments are modeled as three-dimensional elastic springs distributed on one end of the capsule and persistently attached to the motile bacterial surface through an end-tracking motor complex. Filament distribution is random, and monomer concentration decreases linearly as a function of position on the bacterial surface. Filament growth rate increases with monomer concentration but decreases with the extent of compression. The growing filaments exert push-pull forces on the bacterial surface. In addition to forces, torques arise due to two factors—distribution of motors on the bacterial surface, and coupling of torsion upon growth due to the right-handed helicity of F-actin—causing the motile object to undergo simultaneous translation and rotation. The trajectory of the bacterium is simulated by performing a force and torque balance on the bacterium. All simulations use a fixed value of torsion. Simulations show strong alignment of the filaments and the long axis of the bacterium along the direction of motion. In the absence of torsion, the bacterial surface essentially moves along the direction of the long axis. When a small amount of the torsion is applied to the bacterial surface, the bacterium is seen to move in right-handed helical trajectories, consistent with experimental observations.

  14. Flagella-independent surface motility in Salmonella enterica serovar Typhimurium

    PubMed Central

    Park, Sun-Yang; Pontes, Mauricio H.; Groisman, Eduardo A.

    2015-01-01

    Flagella are multiprotein complexes necessary for swimming and swarming motility. In Salmonella enterica serovar Typhimurium, flagella-mediated motility is repressed by the PhoP/PhoQ regulatory system. We now report that Salmonella can move on 0.3% agarose media in a flagella-independent manner when experiencing the PhoP/PhoQ-inducing signal low Mg2+. This motility requires the PhoP-activated mgtA, mgtC, and pagM genes, which specify a Mg2+ transporter, an inhibitor of Salmonella’s own F1Fo ATPase, and a small protein of unknown function, respectively. The MgtA and MgtC proteins are necessary for pagM expression because pagM mRNA levels were lower in mgtA and mgtC mutants than in wild-type Salmonella, and also because pagM expression from a heterologous promoter rescued motility in mgtA and mgtC mutants. PagM promotes group motility by a surface protein(s), as a pagM-expressing strain conferred motility upon a pagM null mutant, and proteinase K treatment eliminated motility. The pagM gene is rarely found outside subspecies I of S. enterica and often present in nonfunctional allelic forms in organisms lacking the identified motility. Deletion of the pagM gene reduced bacterial replication on 0.3% agarose low Mg2+ media but not in low Mg2+ liquid media. Our findings define a form of motility that allows Salmonella to scavenge nutrients and to escape toxic compounds in low Mg2+ semisolid environments. PMID:25624475

  15. Cellular mechanics and motility

    NASA Astrophysics Data System (ADS)

    Hénon, Sylvie; Sykes, Cécile

    2015-10-01

    The term motility defines the movement of a living organism. One widely known example is the motility of sperm cells, or the one of flagellar bacteria. The propulsive element of such organisms is a cilium(or flagellum) that beats. Although cells in our tissues do not have a flagellum in general, they are still able to move, as we will discover in this chapter. In fact, in both cases of movement, with or without a flagellum, cell motility is due to a dynamic re-arrangement of polymers inside the cell. Let us first have a closer look at the propulsion mechanism in the case of a flagellum or a cilium, which is the best known, but also the simplest, and which will help us to define the hydrodynamic general conditions of cell movement. A flagellum is sustained by cellular polymers arranged in semi-flexible bundles and flagellar beating generates cell displacement. These polymers or filaments are part of the cellular skeleton, or "cytoskeleton", which is, in this case, external to the cellular main body of the organism. In fact, bacteria move in a hydrodynamic regime in which viscosity dominates over inertia. The system is thus in a hydrodynamic regime of low Reynolds number (Box 5.1), which is nearly exclusively the case in all cell movements. Bacteria and their propulsion mode by flagella beating are our unicellular ancestors 3.5 billion years ago. Since then, we have evolved to form pluricellular organisms. However, to keep the ability of displacement, to heal our wounds for example, our cells lost their flagellum, since it was not optimal in a dense cell environment: cells are too close to each other to leave enough space for the flagella to accomplish propulsion. The cytoskeleton thus developed inside the cell body to ensure cell shape changes and movement, and also mechanical strength within a tissue. The cytoskeleton of our cells, like the polymers or filaments that sustain the flagellum, is also composed of semi-flexible filaments arranged in bundles, and also in

  16. Symmetry-Breaking Motility

    NASA Astrophysics Data System (ADS)

    Lee, Allen; Lee, Ha Youn; Kardar, Mehran

    2005-09-01

    Locomotion of bacteria by actin polymerization and in vitro motion of spherical beads coated with a protein catalyzing polymerization are examples of active motility. Starting from a simple model of forces locally normal to the surface of a bead, we construct a phenomenological equation for its motion. The singularities at a continuous transition between moving and stationary beads are shown to be related to the symmetries of its shape. Universal features of the phase behavior are calculated analytically and confirmed by simulations. Fluctuations in velocity are shown to be generically non-Maxwellian and correlated to the shape of the bead.

  17. Swimming Motility Reduces Deposition to Silica Surfaces

    SciTech Connect

    Lu, Nanxi; Massoudieh, Arash; Liang, Xiaomeng; Hu, Dehong; Kamai, Tamir; Ginn, Timothy R.; Zilles, Julie L.; Nguyen, Thanh H.

    2015-01-01

    The role of swimming motility on bacterial transport and fate in porous media was evaluated. We present microscopic evidence showing that strong swimming motility reduces attachment of Azotobacter vinelandii cells to silica surfaces. Applying global and cluster statistical analyses to microscopic videos taken under non-flow conditions, wild type, flagellated A. vinelandii strain DJ showed strong swimming ability with an average speed of 13.1 μm/s, DJ77 showed impaired swimming averaged at 8.7 μm/s, and both the non-flagellated JZ52 and chemically treated DJ cells were non-motile. Quantitative analyses of trajectories observed at different distances above the collector of a radial stagnation point flow cell (RSPF) revealed that both swimming and non-swimming cells moved with the flow when at a distance of at least 20 μm from the collector surface. Near the surface, DJ cells showed both horizontal and vertical movement diverging them from reaching surfaces, while chemically treated DJ cells moved with the flow to reach surfaces, suggesting that strong swimming reduced attachment. In agreement with the RSPF results, the deposition rates obtained for two-dimensional multiple-collector micromodels were also lowest for DJ, while DJ77 and JZ52 showed similar values. Strong swimming specifically reduced deposition on the upstream surfaces of the micromodel collectors.

  18. Mechanics of motility initiation and motility arrest in crawling cells

    NASA Astrophysics Data System (ADS)

    Recho, Pierre; Putelat, Thibaut; Truskinovsky, Lev

    2015-11-01

    Motility initiation in crawling cells requires transformation of a symmetric state into a polarized state. In contrast, motility arrest is associated with re-symmetrization of the internal configuration of a cell. Experiments on keratocytes suggest that polarization is triggered by the increased contractility of motor proteins but the conditions of re-symmetrization remain unknown. In this paper we show that if adhesion with the extra-cellular substrate is sufficiently low, the progressive intensification of motor-induced contraction may be responsible for both transitions: from static (symmetric) to motile (polarized) at a lower contractility threshold and from motile (polarized) back to static (symmetric) at a higher contractility threshold. Our model of lamellipodial cell motility is based on a 1D projection of the complex intra-cellular dynamics on the direction of locomotion. In the interest of analytical transparency we also neglect active protrusion and view adhesion as passive. Despite the unavoidable oversimplifications associated with these assumptions, the model reproduces quantitatively the motility initiation pattern in fish keratocytes and reveals a crucial role played in cell motility by the nonlocal feedback between the mechanics and the transport of active agents. A prediction of the model that a crawling cell can stop and re-symmetrize when contractility increases sufficiently far beyond the motility initiation threshold still awaits experimental verification.

  19. Visual, base-specific detection of nucleic acid hybridization using polymerization-based amplification.

    PubMed

    Hansen, Ryan R; Johnson, Leah M; Bowman, Christopher N

    2009-03-15

    Polymerization-based signal amplification offers sensitive visualization of biotinylated biomolecules functionalized to glass microarrays in a manner suitable for point-of-care use. Here we report using this method for visual detection of multiplexed nucleic acid hybridizations from complex media and develop an application toward point mutation detection and single nucleotide polymorphism (SNP) typing. Primer extension reactions were employed to label selectively and universally all complementary surface DNA hybrids with photoinitiators, permitting simultaneous and dynamic photopolymerization from positive sites to 0.5-nM target concentrations. Dramatic improvements in signal ratios between complementary and mismatched hybrids enabled visual discrimination of single base differences in KRAS codon-12 biomarkers.

  20. Non-contact fiber-optical trapping of motile bacteria: dynamics observation and energy estimation

    NASA Astrophysics Data System (ADS)

    Xin, Hongbao; Liu, Qingyuan; Li, Baojun

    2014-10-01

    The dynamics and energy conversion of bacteria are strongly associated with bacterial activities, such as survival, spreading of bacterial diseases and their pathogenesis. Although different discoveries have been reported on trapped bacteria (i.e. immobilized bacteria), the investigation on the dynamics and energy conversion of motile bacteria in the process of trapping is highly desirable. Here, we report a non-contact optical trapping of motile bacteria using a modified tapered optical fiber. Using Escherichia coli as an example, both single and multiple motile bacteria have been trapped and manipulated in a non-contact manner. Bacterial dynamics has been observed and bacterial energy has been estimated in the trapping process. This non-contact optical trapping provides a new opportunity for better understanding the bacterial dynamics and energy conversion at the single cell level.

  1. Rimonabant, Gastrointestinal Motility and Obesity

    PubMed Central

    Sun, Yan; Chen, Jiande

    2012-01-01

    Background: Obesity and overweight affect more than half of the US population and are associated with a number of diseases. Rimonabant, a cannabinoid receptor 1 blocker in the endocannabinoid (EC) system, was indicated in Europe for the treatment of obesity and overweight patients with associated risk factors but withdrawn on Jan, 2009 because of side effects. Many studies have reported the effects of rimonabant on gastrointestinal (GI) motility and food intake. The aims of this review are: to review the relationship of EC system with GI motility and food intake;to review the studies of rimonabant on GI motility, food intake and obesity;and to report the tolerance and side effects of rimonabant. Methods: the literature (Pubmed database) was searched using keywords: rimonabant, obesity and GI motility. Results: GI motility is related with appetite, food intake and nutrients absorption. The EC system inhibits GI motility, reduces emesis and increases food intake; Rimonabant accelerates gastric emptying and intestinal transition but decreases energy metabolism and food intake. There is rapid onset of tolerance to the prokinetic effect of rimonabant. The main side effects of rimonabant are depression and GI symptoms. Conclusions: Rimonabant has significant effects on energy metabolism and food intake, probably mediated via its effects on GI motility. PMID:23449551

  2. Cyclic GMP and Cilia Motility

    PubMed Central

    Wyatt, Todd A.

    2015-01-01

    Motile cilia of the lungs respond to environmental challenges by increasing their ciliary beat frequency in order to enhance mucociliary clearance as a fundamental tenant of innate defense. One important second messenger in transducing the regulable nature of motile cilia is cyclic guanosine 3′,5′-monophosphate (cGMP). In this review, the history of cGMP action is presented and a survey of the existing data addressing cGMP action in ciliary motility is presented. Nitric oxide (NO)-mediated regulation of cGMP in ciliated cells is presented in the context of alcohol-induced cilia function and dysfunction. PMID:26264028

  3. Gliding motility and Por secretion system genes are widespread among members of the phylum bacteroidetes.

    PubMed

    McBride, Mark J; Zhu, Yongtao

    2013-01-01

    The phylum Bacteroidetes is large and diverse, with rapid gliding motility and the ability to digest macromolecules associated with many genera and species. Recently, a novel protein secretion system, the Por secretion system (PorSS), was identified in two members of the phylum, the gliding bacterium Flavobacterium johnsoniae and the nonmotile oral pathogen Porphyromonas gingivalis. The components of the PorSS are not similar in sequence to those of other well-studied bacterial secretion systems. The F. johnsoniae PorSS genes are a subset of the gliding motility genes, suggesting a role for the secretion system in motility. The F. johnsoniae PorSS is needed for assembly of the gliding motility apparatus and for secretion of a chitinase, and the P. gingivalis PorSS is involved in secretion of gingipain protease virulence factors. Comparative analysis of 37 genomes of members of the phylum Bacteroidetes revealed the widespread occurrence of gliding motility genes and PorSS genes. Genes associated with other bacterial protein secretion systems were less common. The results suggest that gliding motility is more common than previously reported. Microscopic observations confirmed that organisms previously described as nonmotile, including Croceibacter atlanticus, "Gramella forsetii," Paludibacter propionicigenes, Riemerella anatipestifer, and Robiginitalea biformata, exhibit gliding motility. Three genes (gldA, gldF, and gldG) that encode an apparent ATP-binding cassette transporter required for F. johnsoniae gliding were absent from two related gliding bacteria, suggesting that the transporter may not be central to gliding motility.

  4. Biomimetic systems for studying actin-based motility.

    PubMed

    Upadhyaya, Arpita; van Oudenaarden, Alexander

    2003-09-16

    Actin polymerization provides a major driving force for eukaryotic cell motility. Successive intercalation of monomeric actin subunits between the plasma membrane and the filamentous actin network results in protrusions of the membrane enabling the cell to move or to change shape. One of the challenges in understanding eukaryotic cell motility is to dissect the elementary biochemical and biophysical steps that link actin polymerization to mechanical force generation. Recently, significant progress was made using biomimetic, in vitro systems that are inspired by the actin-based motility of bacterial pathogens such as Listeria monocytogenes. Polystyrene microspheres and synthetic phospholipid vesicles coated with proteins that initiate actin polymerization display motile behavior similar to Listeria, mimicking the leading edge of lamellipodia and filopodia. A major advantage of these biomimetic systems is that both biochemical and physical parameters can be controlled precisely. These systems provide a test bed for validating theoretical models on force generation and polarity establishment resulting from actin polymerization. In this review, we discuss recent experimental progress using biomimetic systems propelled by actin polymerization and discuss these results in the light of recent theoretical models on actin-based motility.

  5. Elenoside increases intestinal motility

    PubMed Central

    Navarro, E; Alonso, SJ; Navarro, R; Trujillo, J; Jorge, E

    2006-01-01

    AIM: To study the effects of elenoside, an arylnaph-thalene lignan from Justicia hyssopifolia, on gastro-intestinal motility in vivo and in vitro in rats. METHODS: Routine in vivo experimental assessments were catharsis index, water percentage of boluses, intestinal transit, and codeine antagonism. The groups included were vehicle control (propylene glycol-ethanol-plant oil-tween 80), elenoside (i.p. 25 and 50 mg/kg), cisapride (i.p. 10 mg/kg), and codeine phosphate (intragastric route, 50 mg/kg). In vitro approaches used isolated rat intestinal tissues (duodenum, jejunum, and ileum). The effects of elenoside at concentrations of 3.2 x 10-4, 6.4 x 10-4 and 1.2 x 10-3 mol/L, and cisapride at 10-6 mol/L were investigated. RESULTS: Elenoside in vivo produced an increase in the catharsis index and water percentage of boluses and in the percentage of distance traveled by a suspension of activated charcoal. Codeine phosphate antagonized the effect of 25 mg/kg of elenoside. In vitro, elenoside in duodenum, jejunum and ileum produced an initial decrease in the contraction force followed by an increase. Elenoside resulted in decreased intestinal frequency in duodenum, jejunum, and ileum. The in vitro and in vivo effects of elenoside were similar to those produced by cisapride. CONCLUSION: Elenoside is a lignan with an action similar to that of purgative and prokinetics drugs. Elenoside, could be an alternative to cisapride in treatment of gastrointestinal diseases as well as a preventive therapy for the undesirable gastrointestinal effects produced by opioids used for mild to moderate pain. PMID:17131476

  6. Effects of some tricyclic psychopharmacons and structurally related compounds on motility of Proteus vulgaris.

    PubMed

    Molnár, J; Ren, J; Kristiansen, J E; Nakamura, M J

    1992-11-01

    A simple test for the evaluation of drugs interfering with bacterial motility was established with Proteus vulgaris. With this model, promethazine, 7-hydroxy-chlorpromazine, imipramine, 7,8-dioxochlorpromazine and acridine orange were shown to exert significant motility and swarming inhibitory action on Proteus vulgaris strains at subinhibitory concentrations. Quinidine enhanced the antimotility effect of promethazine. The antimotility effect of promethazine was synergized by proton pump inhibitors omeprazole and abscissic acid, but antagonized by extracellular potassium and sodium ions.

  7. Actin-based motility of Listeria: Right-handed helical trajectories

    NASA Astrophysics Data System (ADS)

    Rangarajan, Murali

    2012-06-01

    Bacteria such as Listeria monocytogenes recruit cellular machinery to move in and between cells. Understanding the mechanism of motility, including force and torque generation and the resultant displacements, holds keys to numerous applications in medicine and biosensing. In this work, a simple back-of-the-envelope calculation is presented to illustrate that a biomechanical model of actin-based motility of a rigid surface through persistently attached filaments propelled by affinity-modulated molecular motors can produce a right-handed helical trajectory consistent with experimental observations. The implications of the mechanism to bacterial motility are discussed.

  8. Esophageal motility disorders: medical therapy.

    PubMed

    Lacy, Brian E; Weiser, Kirsten

    2008-01-01

    Symptoms of chest pain and dysphagia are common in the adult population. Most patients initially undergo an evaluation to exclude anatomic causes (ie, esophagitis, stricture) and cardiovascular disease as the etiology of these symptoms. Patients with persistent symptoms may then be referred for specialized testing of the esophagus, including esophageal manometry. Disorders of esophageal motility, which include achalasia, diffuse esophageal spasm, nutcracker esophagus, hypertensive lower esophageal sphincter, and ineffective motility are often identified in these patients. Unfortunately, the etiology of these disorders has not been well characterized and the treatment has not been standardized. This review will briefly discuss the impact, etiology, and diagnosis of esophageal motility disorders, and then focus on the medical management of these disorders using evidence from well-designed, prospective studies, where available.

  9. Flagella and bacterial pathogenicity.

    PubMed

    Duan, Qiangde; Zhou, Mingxu; Zhu, Liqian; Zhu, Guoqiang

    2013-01-01

    As locomotive organelles, flagella allow bacteria to move toward favorable environments. A flagellum consists of three parts: the basal structure (rotary motor), the hook (universal joint), and the filament (helical propeller). For ages, flagella have been generally regarded as important virulence factors, mainly because of their motility property. However, flagella are getting recognized to play multiple roles with more functions besides motility and chemotaxis. Recent evidence has pinpointed that the bacterial flagella participate in many additional processes including adhesion, biofilm formation, virulence factor secretion, and modulation of the immune system of eukaryotic cells. This mini-review summarizes data from recent studies that elucidated how flagella, as a virulence factor, contribute to bacterial pathogenicity.

  10. Shear alters motility of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Molaei, Mehdi; Jalali, Maryam; Sheng, Jian

    2013-11-01

    Understanding of locomotion of microorganisms in shear flows drew a wide range of interests in microbial related topics such as biological process including pathogenic infection and biophysical interactions like biofilm formation on engineering surfaces. We employed microfluidics and digital holography microscopy to study motility of E. coli in shear flows. We controlled the shear flow in three different shear rates: 0.28 s-1, 2.8 s-1, and 28 s-1 in a straight channel with the depth of 200 μm. Magnified holograms, recorded at 15 fps with a CCD camera over more than 20 minutes, are analyzed to obtain 3D swimming trajectories and subsequently used to extract shear responses of E.coli. Thousands of 3-D bacterial trajectories are tracked. The change of bacteria swimming characteristics including swimming velocity, reorientation, and dispersion coefficient are computed directly for individual trajectory and ensemble averaged over thousands of realizations. The results show that shear suppresses the bacterial dispersions in bulk but promote dispersions near the surface contrary to those in quiescent flow condition. Ongoing analyses are focusing to quantify effect of shear rates on tumbling frequency and reorientation of cell body, and its implication in locating the hydrodynamic mechanisms for shear enhanced angular scattering. NIH, NSF, GoMRI.

  11. Coupled effects of chemotaxis and growth on traveling bacterial waves.

    PubMed

    Yan, Zhifeng; Bouwer, Edward J; Hilpert, Markus

    2014-08-01

    Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves.

  12. The swarming motility of Pseudomonas aeruginosa is blocked by cranberry proanthocyanidins and other tannin-containing materials.

    PubMed

    O'May, Che; Tufenkji, Nathalie

    2011-05-01

    Bacterial motility plays a key role in the colonization of surfaces by bacteria and the subsequent formation of resistant communities of bacteria called biofilms. Derivatives of cranberry fruit, predominantly condensed tannins called proanthocyanidins (PACs) have been reported to interfere with bacterial adhesion, but the effects of PACs and other tannins on bacterial motilities remain largely unknown. In this study, we investigated whether cranberry PAC (CPAC) and the hydrolyzable tannin in pomegranate (PG; punicalagin) affected the levels of motilities exhibited by the bacterium Pseudomonas aeruginosa. This bacterium utilizes flagellum-mediated swimming motility to approach a surface, attaches, and then further spreads via the surface-associated motilities designated swarming and twitching, mediated by multiple flagella and type IV pili, respectively. Under the conditions tested, both CPAC and PG completely blocked swarming motility but did not block swimming or twitching motilities. Other cranberry-containing materials and extracts of green tea (also rich in tannins) were also able to block or impair swarming motility. Moreover, swarming bacteria were repelled by filter paper discs impregnated with many tannin-containing materials. Growth experiments demonstrated that the majority of these compounds did not impair bacterial growth. When CPAC- or PG-containing medium was supplemented with surfactant (rhamnolipid), swarming motility was partially restored, suggesting that the effective tannins are in part acting by a rhamnolipid-related mechanism. Further support for this theory was provided by demonstrating that the agar surrounding tannin-induced nonswarming bacteria was considerably less hydrophilic than the agar area surrounding swarming bacteria. This is the first study to show that natural compounds containing tannins are able to block P. aeruginosa swarming motility and that swarming bacteria are repelled by such compounds.

  13. The effects of temperature and motility on the advective transport of a deep subsurface bacteria through saturated sediment

    SciTech Connect

    McCaulou, Douglas Ray

    1993-01-01

    Replicate column experiments were done to quantify the effects of temperature and bacterial motility on advective transport through repacked, but otherwise unaltered, natural aquifer sediment. The bacteria used in this study, A0500, was a flagellated, spore-forming rod isolated from the deep subsurface at DOE`s Savannah River Laboratory. Motility was controlled by turning on flagellar metabolism at 18°C but off at 40°α), estimated using a steady-state filtration model. The observed greater microsphere removal at the higher temperature agreed with the physical-chemical model, but bacteria removal at 18{degrees}C was only half that at 4°C. The sticking efficiency for non-motile A0500 (4°C) was over three times that of the motile A0500 (18°C), 0.073 versus 0.022 respectively. Analysis of complete breakthrough curves using a non-steady, kinetically limited, transport model to estimate the time scales of attachment and detachment suggested that motile A 0500 bacteria traveled twice as far as non-motile A 0500 bacteria before becoming attached. Once attached, non-motile colloids detached on the time scale of 9 to 17 days. The time scale for detachment of motile A0500 bacteria was shorter, 4 to 5 days. Results indicate that bacterial attachment was reversible and detachment was enhanced by bacterial motifity. The kinetic energy of bacterial motility changed the attachment-detachment kinetics in favor of the detached state. The chemical factors responsible for the enhanced transport are not known. However, motility may have caused weakly held bacteria to detach from the secondary minimum, and possibly from the primary minimum, as described by DLVO theory.

  14. Motility of Escherichia coli in a quasi-two-dimensional porous medium

    NASA Astrophysics Data System (ADS)

    Sosa-Hernández, Juan Eduardo; Santillán, Moisés; Santana-Solano, Jesús

    2017-03-01

    Bacterial migration through confined spaces is critical for several phenomena, such as biofilm formation, bacterial transport in soils, and bacterial therapy against cancer. In the present work, E. coli (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-two-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98-μ m -diameter spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing several trajectory parameters (instantaneous velocity, turn angle, mean squared displacement, etc.), and contrasting with the results of a random-walk model developed ad hoc, we were able to quantify the effects that different obstacle concentrations have upon bacterial motility.

  15. Gliding motility in bacteria: insights from studies of Myxococcus xanthus.

    PubMed

    Spormann, A M

    1999-09-01

    motor in M. xanthus controls cell movement in groups (S-motility system). It is dependent on functional type IV pili and is operative only when cells are in close proximity to each other. Type IV pili are known to be involved in another mode of bacterial surface translocation, called twitching motility. S-motility may well represent a variation of twitching motility in M. xanthus. However, twitching differs from gliding since it involves cell movements that are jerky and abrupt and that lack the organization and smoothness observed in gliding. Components of this motor are encoded by genes of the S-system, which appear to be homologs of genes involved in the biosynthesis, assembly, and function of type IV pili in Pseudomonas aeruginosa and Neisseria gonorrhoeae. How type IV pili generate force in S-motility is currently unknown, but it is to be expected that ongoing physiological, genetic, and biochemical studies in M. xanthus, in conjunction with studies on twitching in P. aeruginosa and N. gonorrhoeae, will provide important insights into this microbial motor. The two motility systems of M. xanthus are affected to different degrees by the MglA protein, which shows similarity to a small GTPase. Bacterial chemotaxis-like sensory transduction systems control gliding motility in M. xanthus. The frz genes appear to regulate gliding movement of individual cells and movement by the S-motility system, suggesting that the two motors found in this bacterium can be regulated to result in coordinated multicellular movements. In contrast, the dif genes affect only S-system-dependent swarming.

  16. Gliding Motility in Bacteria: Insights from Studies of Myxococcus xanthus

    PubMed Central

    Spormann, Alfred M.

    1999-01-01

    motor in M. xanthus controls cell movement in groups (S-motility system). It is dependent on functional type IV pili and is operative only when cells are in close proximity to each other. Type IV pili are known to be involved in another mode of bacterial surface translocation, called twitching motility. S-motility may well represent a variation of twitching motility in M. xanthus. However, twitching differs from gliding since it involves cell movements that are jerky and abrupt and that lack the organization and smoothness observed in gliding. Components of this motor are encoded by genes of the S-system, which appear to be homologs of genes involved in the biosynthesis, assembly, and function of type IV pili in Pseudomonas aeruginosa and Neisseria gonorrhoeae. How type IV pili generate force in S-motility is currently unknown, but it is to be expected that ongoing physiological, genetic, and biochemical studies in M. xanthus, in conjunction with studies on twitching in P. aeruginosa and N. gonorrhoeae, will provide important insights into this microbial motor. The two motility systems of M. xanthus are affected to different degrees by the MglA protein, which shows similarity to a small GTPase. Bacterial chemotaxis-like sensory transduction systems control gliding motility in M. xanthus. The frz genes appear to regulate gliding movement of individual cells and movement by the S-motility system, suggesting that the two motors found in this bacterium can be regulated to result in coordinated multicellular movements. In contrast, the dif genes affect only S-system-dependent swarming. PMID:10477310

  17. Motility of Electric Cable Bacteria

    PubMed Central

    Damgaard, Lars Riis; Holm, Simon Agner; Schramm, Andreas; Nielsen, Lars Peter

    2016-01-01

    ABSTRACT Cable bacteria are filamentous bacteria that electrically couple sulfide oxidation and oxygen reduction at centimeter distances, and observations in sediment environments have suggested that they are motile. By time-lapse microscopy, we found that cable bacteria used gliding motility on surfaces with a highly variable speed of 0.5 ± 0.3 μm s−1 (mean ± standard deviation) and time between reversals of 155 ± 108 s. They frequently moved forward in loops, and formation of twisted loops revealed helical rotation of the filaments. Cable bacteria responded to chemical gradients in their environment, and around the oxic-anoxic interface, they curled and piled up, with straight parts connecting back to the source of sulfide. Thus, it appears that motility serves the cable bacteria in establishing and keeping optimal connections between their distant electron donor and acceptors in a dynamic sediment environment. IMPORTANCE This study reports on the motility of cable bacteria, capable of transmitting electrons over centimeter distances. It gives us a new insight into their behavior in sediments and explains previously puzzling findings. Cable bacteria greatly influence their environment, and this article adds significantly to the body of knowledge about this organism. PMID:27084019

  18. Earthquake-like dynamics in Myxococcus xanthus social motility.

    PubMed

    Gibiansky, Maxsim L; Hu, Wei; Dahmen, Karin A; Shi, Wenyuan; Wong, Gerard C L

    2013-02-05

    Myxococcus xanthus is a bacterium capable of complex social organization. Its characteristic social ("S")-motility mechanism is mediated by type IV pili (TFP), linear actuator appendages that propel the bacterium along a surface. TFP are known to bind to secreted exopolysaccharides (EPS), but it is unclear how M. xanthus manages to use the TFP-EPS technology common to many bacteria to achieve its unique coordinated multicellular movements. We examine M. xanthus S-motility, using high-resolution particle-tracking algorithms, and observe aperiodic stick-slip movements. We show that they are not due to chemotaxis, but are instead consistent with a constant TFP-generated force interacting with EPS, which functions both as a glue and as a lubricant. These movements are quantitatively homologous to the dynamics of earthquakes and other crackling noise systems. These systems exhibit critical behavior, which is characterized by a statistical hierarchy of discrete "avalanche" motions described by a power law distribution. The measured critical exponents from M. xanthus are consistent with mean field theoretical models and with other crackling noise systems, and the measured Lyapunov exponent suggests the existence of highly branched EPS. Such molecular architectures, which are common for efficient lubricants but rare in bacterial EPS, may be necessary for S-motility: We show that the TFP of leading "locomotive" cells initiate the collective motion of follower cells, indicating that lubricating EPS may alleviate the force generation requirements on the lead cell and thus make S-motility possible.

  19. Bacterial surface adaptation

    NASA Astrophysics Data System (ADS)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  20. Identification of Novel Factors Involved in Modulating Motility of Salmonella enterica Serotype Typhimurium

    PubMed Central

    Bogomolnaya, Lydia M.; Aldrich, Lindsay; Ragoza, Yuri; Talamantes, Marissa; Andrews, Katharine D.; McClelland, Michael; Andrews-Polymenis, Helene L.

    2014-01-01

    Salmonella enterica serotype Typhimurium can move through liquid using swimming motility, and across a surface by swarming motility. We generated a library of targeted deletion mutants in Salmonella Typhimurium strain ATCC14028, primarily in genes specific to Salmonella, that we have previously described. In the work presented here, we screened each individual mutant from this library for the ability to move away from the site of inoculation on swimming and swarming motility agar. Mutants in genes previously described as important for motility, such as flgF, motA, cheY are do not move away from the site of inoculation on plates in our screens, validating our approach. Mutants in 130 genes, not previously known to be involved in motility, had altered movement of at least one type, 9 mutants were severely impaired for both types of motility, while 33 mutants appeared defective on swimming motility plates but not swarming motility plates, and 49 mutants had reduced ability to move on swarming agar but not swimming agar. Finally, 39 mutants were determined to be hypermotile in at least one of the types of motility tested. Both mutants that appeared non-motile and hypermotile on plates were assayed for expression levels of FliC and FljB on the bacterial surface and many of them had altered levels of these proteins. The phenotypes we report are the first phenotypes ever assigned to 74 of these open reading frames, as they are annotated as ‘hypothetical genes’ in the Typhimurium genome. PMID:25369209

  1. Axoneme Structure from Motile Cilia.

    PubMed

    Ishikawa, Takashi

    2017-01-03

    The axoneme is the main extracellular part of cilia and flagella in eukaryotes. It consists of a microtubule cytoskeleton, which normally comprises nine doublets. In motile cilia, dynein ATPase motor proteins generate sliding motions between adjacent microtubules, which are integrated into a well-orchestrated beating or rotational motion. In primary cilia, there are a number of sensory proteins functioning on membranes surrounding the axoneme. In both cases, as the study of proteomics has elucidated, hundreds of proteins exist in this compartmentalized biomolecular system. In this article, we review the recent progress of structural studies of the axoneme and its components using electron microscopy and X-ray crystallography, mainly focusing on motile cilia. Structural biology presents snapshots (but not live imaging) of dynamic structural change and gives insights into the force generation mechanism of dynein, ciliary bending mechanism, ciliogenesis, and evolution of the axoneme.

  2. Self-organized cell motility

    NASA Astrophysics Data System (ADS)

    Du, Xinxin; Doubrovinski, Konstantin

    2011-03-01

    Cell migration plays a key role in a wide range of biological phenomena, such as morphogenesis, chemotaxis, and wound healing. Cell locomotion relies on the cytoskeleton, a meshwork of filamentous proteins, intrinsically out of thermodynamic equilibrium and cross-linked by molecular motors, proteins that turn chemical energy into mechanical work. In the course of locomotion, cells remain polarized, i.e. they retain a single direction of motion in the absence of external cues. Traditionally, polarization has been attributed to intracellular signaling. However, recent experiments show that polarization may be a consequence of self-organized cytoskeletal dynamics. Our aim is to elucidate the mechanisms by which persistent unidirectional locomotion may arise through simple mechanical interactions of the cytoskeletal proteins. To this end, we develop a simple physical description of cytoskeletal dynamics. We find that the proposed description accounts for a range of phenomena associated with cell motility, including spontaneous polarization, persistent unidirectional motion, and the co-existence of motile and non-motile states.

  3. Screening of a Haloferax volcanii Transposon Library Reveals Novel Motility and Adhesion Mutants.

    PubMed

    Legerme, Georgio; Yang, Evan; Esquivel, Rianne N; Kiljunen, Saija; Savilahti, Harri; Pohlschroder, Mechthild

    2016-11-26

    Archaea, like bacteria, use type IV pili to facilitate surface adhesion. Moreover, archaeal flagella-structures required for motility-share a common ancestry with type IV pili. While the characterization of archaeal homologs of bacterial type IV pilus biosynthesis components has revealed important aspects of flagellum and pilus biosynthesis and the mechanisms regulating motility and adhesion in archaea, many questions remain. Therefore, we screened a Haloferax volcanii transposon insertion library for motility mutants using motility plates and adhesion mutants, using an adapted air-liquid interface assay. Here, we identify 20 genes, previously unknown to affect motility or adhesion. These genes include potential novel regulatory genes that will help to unravel the mechanisms underpinning these processes. Both screens also identified distinct insertions within the genomic region lying between two chemotaxis genes, suggesting that chemotaxis not only plays a role in archaeal motility, but also in adhesion. Studying these genes, as well as hypothetical genes hvo_2512 and hvo_2876-also critical for both motility and adhesion-will likely elucidate how these two systems interact. Furthermore, this study underscores the usefulness of the transposon library to screen other archaeal cellular processes for specific phenotypic defects.

  4. Spirochetal motility and chemotaxis in the natural enzootic cycle and development of Lyme disease.

    PubMed

    Motaleb, Md A; Liu, Jun; Wooten, R Mark

    2015-12-01

    Two-thirds of all bacterial genomes sequenced to-date possess an organelle for locomotion, referred to as flagella, periplasmic flagella or type IV pili. These genomes may also contain a chemotaxis-signaling system which governs flagellar rotation, thus leading a coordinated function for motility. Motility and chemotaxis are often crucial for infection or disease process caused by pathogenic bacteria. Although motility-associated genes are well-characterized in some organisms, the highly orchestrated synthesis, regulation, and assembly of periplasmic flagella in spirochetes are just being delineated. Recent advances were fostered by development of unique genetic manipulations in spirochetes coupled with cutting-edge imaging techniques. These contemporary advances in understanding the role of spirochetal motility and chemotaxis in host persistence and disease development are highlighted in this review.

  5. Spirochetal motility and chemotaxis in the natural enzootic cycle and development of Lyme disease

    PubMed Central

    MOTALEB, MD A.; LIU, JUN; WOOTEN, R. MARK

    2015-01-01

    Two-thirds of all bacterial genomes sequenced to-date possess an organelle for locomotion, referred to as flagella, periplasmic flagella or type IV pili. These genomes may also contain a chemotaxis-signaling system which governs flagellar rotation, thus leading a coordinated function for motility. Motility and chemotaxis are often crucial for infection or disease process caused by pathogenic bacteria. Although motility-associated genes are well-characterized in some organisms, the highly-orchestrated synthesis, regulation, and assembly of periplasmic flagella in spirochetes are just being delineated. Recent advances were fostered by development of unique genetic manipulations in spirochetes coupled with cutting-edge imaging techniques. These contemporary advances in understanding the role of spirochetal motility and chemotaxis in host persistence and disease development are highlighted in this review. PMID:26519910

  6. Cross-regulation of Pseudomonas motility systems: the intimate relationship between flagella, pili and virulence.

    PubMed

    Kazmierczak, Barbara I; Schniederberend, Maren; Jain, Ruchi

    2015-12-01

    Pseudomonas aeruginosa navigates using two distinct forms of motility, swimming and twitching. A polar flagellum and Type 4 pili power these movements, respectively, allowing P. aeruginosa to attach to and colonize surfaces. Single cell imaging and particle tracking algorithms have revealed a wide range of bacterial surface behaviors which are regulated by second messengers cyclic-di-GMP and cAMP; the production of these signals is, in turn, responsive to the engagement of motility organelles with a surface. Innate immune defense systems, long known to recognize structural components of flagella, appear to respond to motility itself. The association of motility with both upregulation of virulence and induction of host defense mechanisms underlies the complex contributions of flagella and pili to P. aeruginosa pathogenesis.

  7. Fundoplication improves disordered esophageal motility.

    PubMed

    Heider, T Ryan; Behrns, Kevin E; Koruda, Mark J; Shaheen, Nicholas J; Lucktong, Tananchai A; Bradshaw, Barbara; Farrell, Timothy M

    2003-02-01

    Patients with gastroesophageal reflux disease (GERD) and disordered esophageal motility are at risk for postoperative dysphagia, and are often treated with partial (270-degree) fundoplication as a strategy to minimize postoperative swallowing difficulties. Complete (360-degree) fundoplication, however, may provide more effective and durable reflux protection over time. Recently we reported that postfundoplication dysphagia is uncommon, regardless of preoperative manometric status and type of fundoplication. To determine whether esophageal function improves after fundoplication, we measured postoperative motility in patients in whom disordered esophageal motility had been documented before fundoplication. Forty-eight of 262 patients who underwent laparoscopic fundoplication between 1995 and 2000 satisfied preoperative manometric criteria for disordered esophageal motility (distal esophageal peristaltic amplitude < or =30 mm Hg and/or peristaltic frequency < or =80%). Of these, 19 had preoperative manometric assessment at our facility and consented to repeat study. Fifteen (79%) of these patients had a complete fundoplication and four (21%) had a partial fundoplication. Each patient underwent repeat four-channel esophageal manometry 29.5 +/- 18.4 months (mean +/- SD) after fundoplication. Distal esophageal peristaltic amplitude and peristaltic frequency were compared to preoperative data by paired t test. After fundoplication, mean peristaltic amplitude in the distal esophagus increased by 47% (56.8 +/- 30.9 mm Hg to 83.5 +/- 36.5 mm Hg; P < 0.001) and peristaltic frequency improved by 33% (66.4 +/- 28.7% to 87.6 +/- 16.3%; P < 0.01). Normal esophageal motor function was present in 14 patients (74%) after fundoplication, whereas in five patients the esophageal motor function remained abnormal (2 improved, 1 worsened, and 2 remained unchanged). Three patients with preoperative peristaltic frequencies of 0%, 10%, and 20% improved to 84%, 88%, and 50%, respectively

  8. Motility and Adhesiveness in Human Neutrophils

    PubMed Central

    Smith, C. Wayne; Hollers, James C.; Patrick, Richard A.; Hassett, Clare

    1979-01-01

    Human peripheral blood neutrophils (PMN) obtained from healthy adults were examined in vitro with techniques adapted to assess the effects of chemotactic factors (CF) on cellular configuration and adhesiveness. The results were compared with those that use certain conventional techniques for assessing chemotaxis and chemokinesis. Exposure of PMN to N-formyl-l-methionyl-l-phenylalanine (f-Met-Phe), zymosan-activated serum, bacterial chemotactic factor, or a low molecular weight chemotactic factor from activated serum (C5a) in the absence of a gradient resulted in a change in cellular shape from a spherical to a polarized configuration in a high percentage of cells. This occurred rapidly in suspension, under conditions designed to exclude a role for cell adhesiveness, and was reversible upon removal of the CF. Restimulation of cells with the CF resulted in reappearance of the polarized configuration to the same extent as on initial stimulation with one exception: f-Met-Phe pretreated cells failed to respond to f-Met-Phe, though they responded fully to the other CF. Each CF caused a significant increase in PMN attachment to protein-coated glass. This enhanced adhesiveness was not reversible upon removal of the CF when the cells were treated under conditions shown to produce chemotactic deactivation. Cells treated under these conditions also exhibited significantly reduced motility on glass and in micropore filters in the absence of a gradient of CF. Bacterial chemotactic factor, even at high concentrations, failed to produce deactivation and did not cause a sustained enhancement of adhesiveness. Images PMID:372238

  9. PilZ Domain Protein FlgZ Mediates Cyclic Di-GMP-Dependent Swarming Motility Control in Pseudomonas aeruginosa

    PubMed Central

    Baker, Amy E.; Diepold, Andreas; Kuchma, Sherry L.; Scott, Jessie E.; Ha, Dae Gon; Orazi, Giulia

    2016-01-01

    ABSTRACT The second messenger cyclic diguanylate (c-di-GMP) is an important regulator of motility in many bacterial species. In Pseudomonas aeruginosa, elevated levels of c-di-GMP promote biofilm formation and repress flagellum-driven swarming motility. The rotation of P. aeruginosa's polar flagellum is controlled by two distinct stator complexes, MotAB, which cannot support swarming motility, and MotCD, which promotes swarming motility. Here we show that when c-di-GMP levels are elevated, swarming motility is repressed by the PilZ domain-containing protein FlgZ and by Pel polysaccharide production. We demonstrate that FlgZ interacts specifically with the motility-promoting stator protein MotC in a c-di-GMP-dependent manner and that a functional green fluorescent protein (GFP)-FlgZ fusion protein shows significantly reduced polar localization in a strain lacking the MotCD stator. Our results establish FlgZ as a c-di-GMP receptor affecting swarming motility by P. aeruginosa and support a model wherein c-di-GMP-bound FlgZ impedes motility via its interaction with the MotCD stator. IMPORTANCE The regulation of surface-associated motility plays an important role in bacterial surface colonization and biofilm formation. c-di-GMP signaling is a widespread means of controlling bacterial motility, and yet the mechanism whereby this signal controls surface-associated motility in P. aeruginosa remains poorly understood. Here we identify a PilZ domain-containing c-di-GMP effector protein that contributes to c-di-GMP-mediated repression of swarming motility by P. aeruginosa. We provide evidence that this effector, FlgZ, impacts swarming motility via its interactions with flagellar stator protein MotC. Thus, we propose a new mechanism for c-di-GMP-mediated regulation of motility for a bacterium with two flagellar stator sets, increasing our understanding of surface-associated behaviors, a key prerequisite to identifying ways to control the formation of biofilm communities. PMID

  10. Coordination of swarming motility, biosurfactant synthesis, and biofilm matrix exopolysaccharide production in Pseudomonas aeruginosa.

    PubMed

    Wang, Shiwei; Yu, Shan; Zhang, Zhenyin; Wei, Qing; Yan, Lu; Ai, Guomin; Liu, Hongsheng; Ma, Luyan Z

    2014-11-01

    Biofilm formation is a complex process in which many factors are involved. Bacterial swarming motility and exopolysaccharides both contribute to biofilm formation, yet it is unclear how bacteria coordinate swarming motility and exopolysaccharide production. Psl and Pel are two key biofilm matrix exopolysaccharides in Pseudomonas aeruginosa. This opportunistic pathogen has three types of motility, swimming, twitching, and swarming. In this study, we found that elevated Psl and/or Pel production reduced the swarming motility of P. aeruginosa but had little effect on swimming and twitching. The reduction was due to decreased rhamnolipid production with no relation to the transcription of rhlAB, two key genes involved in the biosynthesis of rhamnolipids. Rhamnolipid-negative rhlR and rhlAB mutants synthesized more Psl, whereas exopolysaccharide-deficient strains exhibited a hyperswarming phenotype. These results suggest that competition for common sugar precursors catalyzed by AlgC could be a tactic for P. aeruginosa to balance the synthesis of exopolysaccharides and rhamnolipids and to control bacterial motility and biofilm formation inversely because the biosynthesis of rhamnolipids, Psl, and Pel requires AlgC to provide the sugar precursors and an additional algC gene enhances the biosynthesis of Psl and rhamnolipids. In addition, our data indicate that the increase in RhlI/RhlR expression attenuated Psl production. This implied that the quorum-sensing signals could regulate exopolysaccharide biosynthesis indirectly in bacterial communities. In summary, this study represents a mechanism that bacteria utilize to coordinate swarming motility, biosurfactant synthesis, and biofilm matrix exopolysaccharide production, which is critical for biofilm formation and bacterial survival in the environment.

  11. Mechanism of Actin-Based Motility

    NASA Astrophysics Data System (ADS)

    Pantaloni, Dominique; Le Clainche, Christophe; Carlier, Marie-France

    2001-05-01

    Spatially controlled polymerization of actin is at the origin of cell motility and is responsible for the formation of cellular protrusions like lamellipodia. The pathogens Listeria monocytogenes and Shigella flexneri, which undergo actin-based propulsion, are acknowledged models of the leading edge of lamellipodia. Actin-based motility of the bacteria or of functionalized microspheres can be reconstituted in vitro from only five pure proteins. Movement results from the regulated site-directed treadmilling of actin filaments, consistent with observations of actin dynamics in living motile cells and with the biochemical properties of the components of the synthetic motility medium.

  12. Crawling motility through the analysis of model locomotors: two case studies.

    PubMed

    DeSimone, A; Tatone, A

    2012-09-01

    We study model locomotors on a substrate, which derive their propulsive capabilities from the tangential (viscous or frictional) resistance offered by the substrate. Our aim is to develop new tools and insight for future studies of cellular motility by crawling and of collective bacterial motion. The purely viscous case (worm) is relevant for cellular motility by crawling of individual cells. We re-examine some recent results on snail locomotion in order to assess the role of finely regulated adhesion mechanisms in crawling motility. Our main conclusion is that such regulation, although well documented in several biological systems, is not indispensable to accomplish locomotion driven by internal deformations, provided that the crawler may execute sufficiently large body deformations. Thus, there is no snail theorem. Namely, the crawling analog of the scallop theorem of low Reynolds number hydrodynamics does not hold for snail-like crawlers. The frictional case is obtained by assuming that the viscous coefficient governing tangential resistance forces, which act parallel and in the direction opposite to the velocity of the point to which they are applied, depends on the normal force acting at that point. We combine these surface interactions with inertial effects in order to investigate the mechanisms governing the motility of a bristle-robot. This model locomotor is easily manufactured and has been proposed as an effective tool to replicate and study collective bacterial motility.

  13. Earthquake-like dynamics in Myxococcus xanthus social motility

    PubMed Central

    Gibiansky, Maxsim L.; Hu, Wei; Dahmen, Karin A.; Shi, Wenyuan; Wong, Gerard C. L.

    2013-01-01

    Myxococcus xanthus is a bacterium capable of complex social organization. Its characteristic social (“S”)-motility mechanism is mediated by type IV pili (TFP), linear actuator appendages that propel the bacterium along a surface. TFP are known to bind to secreted exopolysaccharides (EPS), but it is unclear how M. xanthus manages to use the TFP-EPS technology common to many bacteria to achieve its unique coordinated multicellular movements. We examine M. xanthus S-motility, using high-resolution particle-tracking algorithms, and observe aperiodic stick–slip movements. We show that they are not due to chemotaxis, but are instead consistent with a constant TFP-generated force interacting with EPS, which functions both as a glue and as a lubricant. These movements are quantitatively homologous to the dynamics of earthquakes and other crackling noise systems. These systems exhibit critical behavior, which is characterized by a statistical hierarchy of discrete “avalanche” motions described by a power law distribution. The measured critical exponents from M. xanthus are consistent with mean field theoretical models and with other crackling noise systems, and the measured Lyapunov exponent suggests the existence of highly branched EPS. Such molecular architectures, which are common for efficient lubricants but rare in bacterial EPS, may be necessary for S-motility: We show that the TFP of leading “locomotive” cells initiate the collective motion of follower cells, indicating that lubricating EPS may alleviate the force generation requirements on the lead cell and thus make S-motility possible. PMID:23341622

  14. Screening of a Haloferax volcanii Transposon Library Reveals Novel Motility and Adhesion Mutants

    PubMed Central

    Legerme, Georgio; Yang, Evan; Esquivel, Rianne N.; Kiljunen, Saija; Savilahti, Harri; Pohlschroder, Mechthild

    2016-01-01

    Archaea, like bacteria, use type IV pili to facilitate surface adhesion. Moreover, archaeal flagella—structures required for motility—share a common ancestry with type IV pili. While the characterization of archaeal homologs of bacterial type IV pilus biosynthesis components has revealed important aspects of flagellum and pilus biosynthesis and the mechanisms regulating motility and adhesion in archaea, many questions remain. Therefore, we screened a Haloferax volcanii transposon insertion library for motility mutants using motility plates and adhesion mutants, using an adapted air–liquid interface assay. Here, we identify 20 genes, previously unknown to affect motility or adhesion. These genes include potential novel regulatory genes that will help to unravel the mechanisms underpinning these processes. Both screens also identified distinct insertions within the genomic region lying between two chemotaxis genes, suggesting that chemotaxis not only plays a role in archaeal motility, but also in adhesion. Studying these genes, as well as hypothetical genes hvo_2512 and hvo_2876—also critical for both motility and adhesion—will likely elucidate how these two systems interact. Furthermore, this study underscores the usefulness of the transposon library to screen other archaeal cellular processes for specific phenotypic defects. PMID:27898036

  15. 21 CFR 876.1725 - Gastrointestinal motility monitoring system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gastrointestinal motility monitoring system. 876... Gastrointestinal motility monitoring system. (a) Identification. A gastrointestinal motility monitoring system is a... esophageal motility monitor and tube, the gastrointestinal motility (electrical) system, and...

  16. 21 CFR 876.1725 - Gastrointestinal motility monitoring system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gastrointestinal motility monitoring system. 876... Gastrointestinal motility monitoring system. (a) Identification. A gastrointestinal motility monitoring system is a... esophageal motility monitor and tube, the gastrointestinal motility (electrical) system, and...

  17. 21 CFR 876.1725 - Gastrointestinal motility monitoring system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gastrointestinal motility monitoring system. 876... Gastrointestinal motility monitoring system. (a) Identification. A gastrointestinal motility monitoring system is a... esophageal motility monitor and tube, the gastrointestinal motility (electrical) system, and...

  18. 21 CFR 876.1725 - Gastrointestinal motility monitoring system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gastrointestinal motility monitoring system. 876... Gastrointestinal motility monitoring system. (a) Identification. A gastrointestinal motility monitoring system is a... esophageal motility monitor and tube, the gastrointestinal motility (electrical) system, and...

  19. 21 CFR 876.1725 - Gastrointestinal motility monitoring system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gastrointestinal motility monitoring system. 876... Gastrointestinal motility monitoring system. (a) Identification. A gastrointestinal motility monitoring system is a... esophageal motility monitor and tube, the gastrointestinal motility (electrical) system, and...

  20. Regulatory mimicry in Listeria monocytogenes actin-based motility

    PubMed Central

    Chong, Ryan; Swiss, Rachel; Briones, Gabriel; Stone, Kathryn L.; Gulcicek, Erol E.; Agaisse, Hervé

    2009-01-01

    Summary The actin-based motility of the intracellular pathogen Listeria monocytogenes relies on ActA, a bacterial factor mimicking the activity of host cell nucleation-promoting factors of the WASP/WAVE family. The activity of WASP and WAVE is tightly regulated in cells. However, it is not known whether the activity of ActA is regulated upon L. monocytogenes infection. Here, we used an RNAi-based genetic approach in combination with computer-assisted image analysis to investigate the role of host factors in L. monocytogenes spread from cell to cell. We showed that the host cell serine/threonine kinase CK2 is required for efficient actin tail formation. We demonstrated that, similar to WASP and WAVE, the affinity of ActA for the ARP2/3 complex is regulated by CK2-mediated phosphorylation. We also demonstrated the importance of this regulatory mechanism in a mouse model of infection. Our work suggests that ActA is a bacterial virulence factor that not only displays a structural mimic of the VCA domain of WASP/WAVE family members, but also co-opted CK2 as the host cell factor regulating its activity, a form of mimicry that we refer to as regulatory mimicry. We present comparative evidence supporting the notion that unrelated pathogens displaying actin-based motility may have evolved a similar strategy. PMID:19748468

  1. Active gel model of amoeboid cell motility

    NASA Astrophysics Data System (ADS)

    Callan-Jones, A. C.; Voituriez, R.

    2013-02-01

    We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-substrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.

  2. Sperm motility under conditions of weightlessness.

    PubMed

    Engelmann, U; Krassnigg, F; Schill, W B

    1992-01-01

    The aim of this study was to determine the differences in motility of frozen and thawed bull spermatozoa under conditions of weightlessness compared with ground conditions. The tests were performed within a series of scientific and technologic experiments under microgravity using sounding rockets in the Technologische Experimente unter Schwerelosigkeit (TEXUS) program launched in Kiruna, North Sweden. Using a computerized sperm motility analyzer, significant differences were found in sperm motility under microgravity compared with sperm under gravitational conditions on earth. Computer analysis showed alterations in straight line and curvilinear velocity, as well as in linearity values. The amount of progressively motile spermatozoa, including all spermatozoa with a velocity > 20 microns/second, increased significantly from 24% +/- 9.5% in the reference test to 49% +/- 7.6% in the microgravity test. In conclusion, there is strong evidence that gravity influences sperm motility.

  3. Swimming motility, a virulence trait of Ralstonia solanacearum, is regulated by FlhDC and the plant host environment.

    PubMed

    Tans-Kersten, Julie; Brown, Darby; Allen, Caitilyn

    2004-06-01

    Swimming motility allows the bacterial wilt pathogen Ralstonia solanacearum to efficiently invade and colonize host plants. However, the bacteria are essentially nonmotile once inside plant xylem vessels. To determine how and when motility genes are expressed, we cloned and mutated flhDC, which encodes a major regulator of flagellar biosynthesis and bacterial motility. An flhDC mutant was nonmotile and less virulent than its wild-type parent on both tomato and Arabidopsis; on Arabidopsis, the flhDC mutant also was less virulent than a nonmotile fliC flagellin mutant. Genes in the R. solanacearum motility regulon had strikingly different expression patterns in culture and in the plant. In culture, as expected, flhDC expression depended on PehSR, a regulator of early virulence factors; and, in turn, FlhDC was required for fliC (flagellin) expression. However, when bacteria grew in tomato plants, flhDC was expressed in both wild-type and pehR mutant backgrounds, although PehSR is necessary for motility both in culture and in planta. Both flhDC and pehSR were significantly induced in planta relative to expression levels in culture. Unexpectedly, the fliC gene was expressed in planta at cell densities where motile bacteria were not observed, as well as in a nonmotile flhDC mutant. Thus, expression of flhDC and flagellin itself are uncoupled from bacterial motility in the host environment, indicating that additional signals and regulatory circuits repress motility during plant pathogenesis.

  4. Targeting motility properties of bacteria in the development of probiotic cultures against Campylobacter jejuni in broiler chickens.

    PubMed

    Aguiar, Vivian F; Donoghue, Ann M; Arsi, Komala; Reyes-Herrera, Ixchel; Metcalf, Joel H; de los Santos, Fausto S; Blore, Pamela J; Donoghue, Dan J

    2013-05-01

    Campylobacter is the leading cause of gastroenteritis worldwide. Campylobacter is commonly present in the intestinal tract of poultry, and one strategy to reduce enteric colonization is the use of probiotic cultures. This strategy has successfully reduced enteric colonization of Salmonella, but has had limited success against Campylobacter. In an effort to improve the efficacy of probiotic cultures, we developed a novel in vitro screening technique for selecting bacterial isolates with enhanced motility. It is proposed that motility-selected bacteria have the marked ability to reach the same gastrointestinal niche in poultry and competitively reduce C. jejuni. Bacterial isolates were collected from ceca of healthy chickens, and motile isolates were identified and tested for anti-Campylobacter activity. Isolates with these properties were selected for increased motility by passing each isolate 10 times and at each passage selecting bacteria that migrated the farthest during each passage. Three bacterial isolates with the greatest motility (all Bacillus subtilis) were used alone or in combination in two chicken trials. At day of hatch, chicks were administered these isolates alone or in combination (n=10/treatment, two trials), and chicks were orally challenged with a mixture of four different wild-type strains of C. jejuni (∼10(5) CFU/mL) on day 7. Isolate 1 reduced C. jejuni colonization in both of the trials (p<0.05). A follow-up study was conducted to compare isolate 1 subjected to enhanced motility selection with its nonselected form. A reduction (p<0.05) in Campylobacter colonization was observed in all three trials in the chickens dosed using isolate with enhanced motility compared to the control and unselected isolate. These findings support the theory that the motility enhancement of potential probiotic bacteria may provide a strategy for reduction of C. jejuni in preharvest chickens.

  5. Regulation of flagellar motility during biofilm formation

    PubMed Central

    Guttenplan, Sarah B.; Kearns, Daniel B.

    2013-01-01

    Many bacteria swim in liquid or swarm over solid surfaces by synthesizing rotary flagella. The same bacteria that are motile also commonly form non-motile multicellular aggregates held together by an extracellular matrix called biofilms. Biofilms are an important part of the lifestyle of pathogenic bacteria and it is assumed that there is a motility-to-biofilm transition wherein the inhibition of motility promotes biofilm formation. The transition is largely inferred from regulatory mutants that reveal the opposite regulation of the two phenotypes. Here we review the regulation of motility during biofilm formation in Bacillus, Pseudomonas, Vibrio, and Escherichia, and we conclude that the motility-to-biofilm transition, if necessary, likely involves two steps. In the short term, flagella are functionally regulated to either inhibit rotation or modulate the basal flagellar reversal frequency. Over the long term, flagellar gene transcription is inhibited and in the absence of de novo synthesis, flagella are likely diluted to extinction through growth. Both short term and long term control is likely important to the motility-to-biofilm transition to stabilize aggregates and optimize resource investment. We emphasize the newly discovered classes of flagellar functional regulators and speculate that others await discovery in the context of biofilm formation. PMID:23480406

  6. Modulation of mammalian sperm motility by quercetin.

    PubMed

    Nass-Arden, L; Breitbart, H

    1990-04-01

    The flavonoid quercetin inhibits collective motility of ejaculated ram spermatozoa in the first 2 hr of incubation; during the next 3-4 hr motility is stimulated. To explain this interesting effect, we followed the influence of quercetin on sperm glycolysis, extracellular pH, ATP content, mitochondrial respiration, and lipid peroxidation. The collective motility of untreated cells is decreased to about 40% of the original motility during two hours of incubation. During this time, the rate of glycolysis is constant, respiration rate is increasing, there is no change in ATP content, the rate of lipid peroxidation is very slow, and the extracellular pH became very acidic (pH 5.5). It is concluded that motility is decreased due to this acidification. This acidification is prevented to some extent by quercetin, which indirectly inhibits glycolysis. Quercetin inhibits motility due to the inhibition of the plasma membrane calcium pump, as we showed previously (Breitbart et al., J Biol Chem 260:11548-11553, 1985). The motility of untreated cells is arrested after 3.5 hr of incubation, whereas quercetin-treated cells show high motility, which continues for additional 2-3 hr. After 3.5 hr, the control cells show no glycolytic activity, ATP content and respiration rates are decreased, and rate of lipid peroxidation is highly increased. At this time, quercetin-treated cells show no glycolytic activity, only a small decrease in ATP content and respiratory rate, and a very low rate of lipid peroxidation. Based on these data it is concluded that sperm motility after 3.5 hr of incubation is dependent mainly on mitochondrial respiration.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Bacterial ratchet motors

    PubMed Central

    Di Leonardo, R.; Angelani, L.; Dell’Arciprete, D.; Ruocco, G.; Iebba, V.; Schippa, S.; Conte, M. P.; Mecarini, F.; De Angelis, F.; Di Fabrizio, E.

    2010-01-01

    Self-propelling bacteria are a nanotechnology dream. These unicellular organisms are not just capable of living and reproducing, but they can swim very efficiently, sense the environment, and look for food, all packaged in a body measuring a few microns. Before such perfect machines can be artificially assembled, researchers are beginning to explore new ways to harness bacteria as propelling units for microdevices. Proposed strategies require the careful task of aligning and binding bacterial cells on synthetic surfaces in order to have them work cooperatively. Here we show that asymmetric environments can produce a spontaneous and unidirectional rotation of nanofabricated objects immersed in an active bacterial bath. The propulsion mechanism is provided by the self-assembly of motile Escherichia coli cells along the rotor boundaries. Our results highlight the technological implications of active matter’s ability to overcome the restrictions imposed by the second law of thermodynamics on equilibrium passive fluids. PMID:20457936

  8. Regulation of Eukaryotic Flagellar Motility

    NASA Astrophysics Data System (ADS)

    Mitchell, David R.

    2005-03-01

    The central apparatus is essential for normal eukaryotic flagellar bend propagation as evidenced by the paralysis associated with mutations that prevent central pair (CP) assembly. Interactions between doublet-associated radial spokes and CP projections are thought to modulate spoke-regulated protein kinases and phosphatases on outer doublets, and these enzymes in turn modulate dynein activity. To better understand CP control mechanisms, we determined the three-dimensional structure of the Chlamydomonas reinhardtii CP complex and analyzed CP orientation during formation and propagation of flagellar bending waves. We show that a single CP microtubule, C1, is near the outermost doublet in curved regions of the flagellum, and this orientation is maintained by twists between successive principal and reverse bends. The Chlamydomonas CP is inherently twisted; twists are not induced by bend formation, and do not depend on forces or signals transmitted through spoke-central pair interactions. We hypothesize that CP orientation passively responds to bend formation, and that bend propagation drives rotation of the CP and maintains a constant CP orientation in bends, which in turn permits signal transduction between specific CP projections and specific doublet-associated dyneins through radial spokes. The central pair kinesin, Klp1, although essential for normal motility, is therefore not the motor that drives CP rotation. The CP also acts as a scaffold for enzymes that maintain normal intraflagellar ATP concentration.

  9. Deterministic patterns in cell motility

    NASA Astrophysics Data System (ADS)

    Lavi, Ido; Piel, Matthieu; Lennon-Duménil, Ana-Maria; Voituriez, Raphaël; Gov, Nir S.

    2016-12-01

    Cell migration paths are generally described as random walks, associated with both intrinsic and extrinsic noise. However, complex cell locomotion is not merely related to such fluctuations, but is often determined by the underlying machinery. Cell motility is driven mechanically by actin and myosin, two molecular components that generate contractile forces. Other cell functions make use of the same components and, therefore, will compete with the migratory apparatus. Here, we propose a physical model of such a competitive system, namely dendritic cells whose antigen capture function and migratory ability are coupled by myosin II. The model predicts that this coupling gives rise to a dynamic instability, whereby cells switch from persistent migration to unidirectional self-oscillation, through a Hopf bifurcation. Cells can then switch to periodic polarity reversals through a homoclinic bifurcation. These predicted dynamic regimes are characterized by robust features that we identify through in vitro trajectories of dendritic cells over long timescales and distances. We expect that competition for limited resources in other migrating cell types can lead to similar deterministic migration modes.

  10. Bacterial population autowave patterns: spontaneous symmetry bursting

    NASA Astrophysics Data System (ADS)

    Medvinsky, A. B.; Tsyganov, M. A.; Karpov, V. A.; Kresteva, I. B.; Shakhbazian, V. Yu.; Ivanitsky, G. R.

    1994-12-01

    Bacteria are known to form autowave patterns (population waves) like those formed by propagating nerve impulses, phase transitions, concentration waves in the Belousov-Zhabotinsky reaction, etc. The formation of bacterial waves is due to the ability of bacteria to drift (through chemotaxis) into the regions with higher attractant concentration. As a result, in contrast to other types of autowaves, bacterial population waves have not only a diffusion component of a bacterial flow but a chemotaxis flow as well. We present the experimental results of the study of spontaneous symmetry loss of bacterial autowave patterns. We show that this phenomenon can be simulated with a simple cellular automata model, and symmetry bursting depends on the parameters characterizing chemotactic sensitivity and motility of the cells forming the population wave. In the experiments in vivo we show that the distortion of a bacterial wave shape can be initiated by bacterial density fluctuations in the parent population that the bacterial waves flake off from.

  11. Mammalian Sperm Motility: Observation and Theory

    NASA Astrophysics Data System (ADS)

    Gaffney, E. A.; Gadêlha, H.; Smith, D. J.; Blake, J. R.; Kirkman-Brown, J. C.

    2011-01-01

    Mammalian spermatozoa motility is a subject of growing importance because of rising human infertility and the possibility of improving animal breeding. We highlight opportunities for fluid and continuum dynamics to provide novel insights concerning the mechanics of these specialized cells, especially during their remarkable journey to the egg. The biological structure of the motile sperm appendage, the flagellum, is described and placed in the context of the mechanics underlying the migration of mammalian sperm through the numerous environments of the female reproductive tract. This process demands certain specific changes to flagellar movement and motility for which further mechanical insight would be valuable, although this requires improved modeling capabilities, particularly to increase our understanding of sperm progression in vivo. We summarize current theoretical studies, highlighting the synergistic combination of imaging and theory in exploring sperm motility, and discuss the challenges for future observational and theoretical studies in understanding the underlying mechanics.

  12. Hydrodynamic effects on microcapillary motility and chemotaxis assays of Methylosinus trichosporium OB3b.

    PubMed Central

    Shonnard, D R; Taylor, R T; Tompson, A; Knapp, R B

    1992-01-01

    A study of the random motility and chemotaxis of Methylosinus trichosporium OB3b was conducted by using Palleroni-chamber microcapillary assay procedures. Under the growth conditions employed, this methanotroph was observed qualitatively with a microscope to be either slightly motile or essentially nonmotile. However, the cells did not not respond in the microcapillary assays in the manner expected for nonmotile Brownian particles. As a consequence, several hydrodynamic effects on these Palleroni microcapillary assays were uncovered. In the random-motility microcapillary assay, nondiffusive cell accumulations occurred that were strongly dependent upon cell concentration. An apparent minimal random-motility coefficient (mu) for this bacterial cell of 1.0 x 10(-7) cm2/s was estimated from microcapillary assays. A simple alternative spectrophotometric assay, based upon gravitational settling, was developed and shown to be an improvement over the Palleroni microcapillary motility assay for M. trichosporium OB3b in that it yielded a more-accurate threefold-lower random-motility coefficient. In addition, it provided a calculation of the gravitational-settling velocity. In the chemotaxis microcapillary assay, the apparent chemotactic responses were strongest for the highest test-chemical concentrations in the microcapillaries, were correlated with microcapillary fluid density, and were strongly dependent upon the microcapillary volume. A simple method to establish the maximal concentration of a chemical that can be tested and to quantify any contributions of abiotic convection is described. Investigators should be aware of the potential problems due to density-driven convection when using these commonly employed microcapillary assays for studying cells which have low motilities. PMID:1444383

  13. Select Acetophenones Modulate Flagellar Motility in Chlamydomonas

    PubMed Central

    Evans, Shakila K.; Pearce, Austin A.; Ibezim, Prudence K.; Primm, Todd P.; Gaillard, Anne R.

    2009-01-01

    Acetophenones were screened for activity against positive phototaxis of Chlamydomonas cells, a process that requires coordinated flagellar motility. The structure-activity relationships of a series of acetophenones are reported, including acetophenones that affect flagellar motility and cell viability. Notably, 4-methoxyacetophenone, 3,4-dimethoxyacetophenone, and 4-hydroxyacetophenone induced negative phototaxis in Chlamydomonas, suggesting interference with activity of flagellar proteins and control of flagellar dominance. PMID:20659114

  14. Temperature and pyoverdine-mediated iron acquisition control surface motility of Pseudomonas putida.

    PubMed

    Matilla, Miguel A; Ramos, Juan L; Duque, Estrella; de Dios Alché, Juan; Espinosa-Urgel, Manuel; Ramos-González, María Isabel

    2007-07-01

    Pseudomonas putida KT2440 is unable to swarm at its common temperature of growth in the laboratory (30 degrees C) but exhibits surface motility similar to swarming patterns in other Pseudomonas between 18 degrees C and 28 degrees C. These motile cells show differentiation, consisting on elongation and the presence of surface appendages. Analysis of a collection of mutants to define the molecular determinants of this type of surface movement in KT2440 shows that while type IV pili and lipopolysaccharide O-antigen are requisites flagella are not. Although surface motility of flagellar mutants was macroscopically undistinguishable from that of the wild type, microscopy analysis revealed that these mutants move using a distinct mechanism to that of the wild-type strain. Mutants either in the siderophore pyoverdine (ppsD) or in the FpvA siderophore receptor were also unable to spread on surfaces. Motility in the ppsD strain was totally restored with pyoverdine and partially with the wild-type ppsD allele. Phenotype of the fpvA strain was not complemented by this siderophore. We discuss that iron influences surface motility and that it can be an environmental cue for swarming-like movement in P. putida. This study constitutes the first report assigning an important role to pyoverdine iron acquisition in en masse bacterial surface movement.

  15. Toward the reconstitution of synthetic cell motility

    PubMed Central

    Siton-Mendelson, Orit; Bernheim-Groswasser, Anne

    2016-01-01

    ABSTRACT Cellular motility is a fundamental process essential for embryonic development, wound healing, immune responses, and tissues development. Cells are mostly moving by crawling on external, or inside, substrates which can differ in their surface composition, geometry, and dimensionality. Cells can adopt different migration phenotypes, e.g., bleb-based and protrusion-based, depending on myosin contractility, surface adhesion, and cell confinement. In the few past decades, research on cell motility has focused on uncovering the major molecular players and their order of events. Despite major progresses, our ability to infer on the collective behavior from the molecular properties remains a major challenge, especially because cell migration integrates numerous chemical and mechanical processes that are coupled via feedbacks that span over large range of time and length scales. For this reason, reconstituted model systems were developed. These systems allow for full control of the molecular constituents and various system parameters, thereby providing insight into their individual roles and functions. In this review we describe the various reconstituted model systems that were developed in the past decades. Because of the multiple steps involved in cell motility and the complexity of the overall process, most of the model systems focus on very specific aspects of the individual steps of cell motility. Here we describe the main advancement in cell motility reconstitution and discuss the main challenges toward the realization of a synthetic motile cell. PMID:27019160

  16. Tumor invasion as dysregulated cell motility.

    PubMed

    Kassis, J; Lauffenburger, D A; Turner, T; Wells, A

    2001-04-01

    Investigations across a range of disciplines over the past decade have brought the study of cell motility and its role in invasion to an exciting threshold. The biophysical forces proximally involved in generating cell locomotion, as well as the underlying signaling and genomic regulatory processes, are gradually becoming elucidated. We now appreciate the intricacies of the many cellular and extracellular events that modulate cell migration. This has enabled the demonstration of a causal role of cell motility in tumor progression, with various points of 'dysregulation' of motility being responsible for promoting invasion. In this paper, we describe key fundamental principles governing cell motility and branch out to describe the essence of the data that describe these principles. It has become evident that many proposed models may indeed be converging into a tightly-woven tapestry of coordinated events which employ various growth factors and their receptors, adhesion receptors (integrins), downstream molecules, cytoskeletal components, and altered genomic regulation to accomplish cell motility. Tumor invasion occurs in response to dysregulation of many of these modulatory points; specific examples include increased signaling from the EGF receptor and through PLC gamma, altered localization and expression of integrins, changes in actin modifying proteins and increased transcription from specific promoter sites. This diversity of alterations all leading to tumor invasion point to the difficulty of correcting causal events leading to tumor invasion and rather suggest that the underlying common processes required for motility be targeted for therapeutic intervention.

  17. Flagellar motility in eukaryotic human parasites.

    PubMed

    Krüger, Timothy; Engstler, Markus

    2015-10-01

    A huge variety of protists rely on one or more motile flagella to either move themselves or move fluids and substances around them. Many of these flagellates have evolved a symbiotic or parasitic lifestyle. Several of the parasites have adapted to human hosts, and include agents of prevalent and serious diseases. These unicellular parasites have become specialised in colonising a wide range of biological niches within humans. They usually have diverse transmission cycles, and frequently manifest a variety of distinct morphological stages. The motility of the single or multiple flagella plays important but understudied roles in parasite transmission, host invasion, dispersal, survival, proliferation and pathology. In this review we provide an overview of the important human pathogens that possess a motile flagellum for at least part of their life cycle. We highlight recently published studies that aim to elucidate motility mechanisms, and their relevance for human disease. We then bring the physics of swimming at the microscale into context, emphasising the importance of interdisciplinary approaches for a full understanding of flagellate motility - especially in light of the parasites' microenvironments and population dynamics. Finally, we summarise some important technological aspects, describing challenges for the field and possibilities for motility analyses in the future.

  18. Decoding the Chemical Language of Motile Bacteria by Using High-Throughput Microfluidic Assays.

    PubMed

    Crooks, John A; Stilwell, Matthew D; Oliver, Piercen M; Zhong, Zhou; Weibel, Douglas B

    2015-10-12

    Motile bacteria navigate chemical environments by using chemoreceptors. The output of these protein sensors is linked to motility machinery and enables bacteria to follow chemical gradients. Understanding the chemical specificity of different families of chemoreceptors is essential for predicting and controlling bacterial behavior in ecological niches, including symbiotic and pathogenic interactions with plants and mammals. The identification of chemical(s) recognized by specific families of receptors is limited by the low throughput and complexity of chemotaxis assays. To address this challenge, we developed a microfluidic-based chemotaxis assay that is quantitative, simple, and enables high-throughput measurements of bacterial response to different chemicals. Using the model bacterium Escherichia coli, we demonstrated a strategy for identifying molecules that activate chemoreceptors from a diverse compound library and for determining how global behavioral strategies are tuned to chemical environments.

  19. The Gas Vacuole - an Early Organelle of Prokaryote Motility

    NASA Astrophysics Data System (ADS)

    Staley, James T.

    1980-06-01

    Several lines of evidence suggest that the gas vesicle may have been an early organelle of prokaryote motility. First, it is found in bacteria that are thought to be representatives of primitive groups. Second, it is a simple structure, and the structure alone imparts the function of motility. Thirdly, it is widely distributed amongst prokaryotes, having been found in the purple and green sulfur photosynthetic bacteria, cyanobacteria, methanogenic bacteria, obligate and facultative anaerobic heterotrophic bacteria, as well as aerobic heterotrophic bacteria that divide by budding and binary transverse fission. Recent evidence suggests that in some bacteria the genes for gas vesicle synthesis occur on plasmids. Thus, the wide distribution of this characteristic could be due to recent evolution and rapid dispersal, though early evolution is not precluded. Though the gas vesicle structure itself appears to be highly conserved among the various groups of bacteria, it seems doubtful that the regulatory mechanism to control its synthesis could be the same for the diverse gas vacuolate bacterial groups.

  20. LBP based detection of intestinal motility in WCE images

    NASA Astrophysics Data System (ADS)

    Gallo, Giovanni; Granata, Eliana

    2011-03-01

    In this research study, a system to support medical analysis of intestinal contractions by processing WCE images is presented. Small intestine contractions are among the motility patterns which reveal many gastrointestinal disorders, such as functional dyspepsia, paralytic ileus, irritable bowel syndrome, bacterial overgrowth. The images have been obtained using the Wireless Capsule Endoscopy (WCE) technique, a patented, video colorimaging disposable capsule. Manual annotation of contractions is an elaborating task, since the recording device of the capsule stores about 50,000 images and contractions might represent only the 1% of the whole video. In this paper we propose the use of Local Binary Pattern (LBP) combined with the powerful textons statistics to find the frames of the video related to contractions. We achieve a sensitivity of about 80% and a specificity of about 99%. The achieved high detection accuracy of the proposed system has provided thus an indication that such intelligent schemes could be used as a supplementary diagnostic tool in endoscopy.

  1. Fourier analysis of cell motility: correlation of motility with metastatic potential.

    PubMed Central

    Partin, A W; Schoeniger, J S; Mohler, J L; Coffey, D S

    1989-01-01

    We report the development of a computerized, mathematical system for quantitating the various types of cell motility. This Fourier analysis method simultaneously quantifies for individual cells (i) temporal changes in cell shape represented by cell ruffling, undulation, and pseudopodal extension, (ii) cell translation, and (iii) average cell size and shape. This spatial-temporal Fourier analysis was tested on a series of well-characterized animal tumor cell lines of rat prostatic cancer to study in a quantitative manner the correlation of cell motility with increasing in vivo metastatic potential. Fourier motility coefficients measuring pseudopodal extension correlated best with metastatic potential in the cell lines studied. This study demonstrated that Fourier analysis provides quantitative measurement of cell motility that may be applied to the study of biological processes. This analysis should aid in the study of the motility of individual cells in various areas of cellular and tumor biology. Images PMID:2919174

  2. Motility modes of the parasite Trypanosoma brucei

    NASA Astrophysics Data System (ADS)

    Temel, Fatma Zeynep; Qu, Zijie; McAllaster, Michael; de Graffenried, Christopher; Breuer, Kenneth

    2015-11-01

    The parasitic single-celled protozoan Trypanosoma brucei causes African Sleeping Sickness, which is a fatal disease in humans and animals that threatens more than 60 million people in 36 African countries. Cell motility plays a critical role in the developmental phases and dissemination of the parasite. Unlike many other motile cells such as bacteria Escherichia coli or Caulobacter crescentus, the flagellum of T. brucei is attached along the length of its awl-like body, producing a unique mode of motility that is not fully understood or characterized. Here, we report on the motility of T. brucei, which swims using its single flagellum employing both rotating and undulating propulsion modes. We tracked cells in real-time in three dimensions using fluorescent microscopy. Data obtained from experiments using both short-term tracking within the field of view and long-term tracking using a tracking microscope were analyzed. Motility modes and swimming speed were analyzed as functions of cell size, rotation rate and undulation pattern. Research supported by NSF.

  3. Study of human sperm motility post cryopreservation

    PubMed Central

    Oberoi, Bhavni; Kumar, Sushil; Talwar, Pankaj

    2014-01-01

    Background Cryopreservation of spermatozoa is a widely used technique to preserve the fertility of males. It can also benefit the armed forces personnel who are to be sent for long recruitments, while leaving their families behind. This study, apart from studying the effects of freezing and thawing, reveals the effect of the post thaw interval on the motility of the human spermatozoa and thus widens the insemination window period. Methods A detailed semen analysis was carried out as per the WHO guidelines for 25 samples. The samples were then washed, analysed and frozen in liquid nitrogen. The semen samples were subsequently thawed and similarly analysed after 20 min and 40 min of thawing. This was then followed by statistical analysis of the comparative motilities. Results Motility of sperms is found to decrease after cryopreservation. However, the study revealed that after thawing a significant increase in the motility of the sperms was noted with the progression of time (p < 0.05). Conclusion By simulating conditions similar to the in vivo conditions for the post thaw semen samples, we can safely wait, confirm the parameters like motility and count, and then inseminate the samples instead of blindly inseminating them immediately after thawing. PMID:25382909

  4. Morphological and biochemical characteristics of bacterial isolates degrading crude oil

    SciTech Connect

    Janiyani, K.L.; Wate, S.R.; Joshi, S.R. )

    1993-01-01

    A mixed bacterial culture developed by soil enrichment procedure using crude oil as a substrate was screened for individual bacterial species. Studies on morphological and biochemical characterization of eleven dominant bacterial isolates revealed that most of the cultures were gram-negative motile rods, and were catalase and oxidase positive. It was observed that four bacterial isolates were efficient in degrading pure hydrocarbons, model petroleum and crude oil. Identification of dominant bacterial cultures confirmed the isolates as Pseudomonas stutzeri, Pseudomonas aeruginoss, Bacillus cereus and Pseudomonas fluorescens. 28 refs., 8 tabs.

  5. Light regulation of swarming motility in Pseudomonas syringae integrates signaling pathways mediated by a bacteriophytochrome and a LOV protein.

    PubMed

    Wu, Liang; McGrane, Regina S; Beattie, Gwyn A

    2013-06-11

    The biological and regulatory roles of photosensory proteins are poorly understood for nonphotosynthetic bacteria. The foliar bacterial pathogen Pseudomonas syringae has three photosensory protein-encoding genes that are predicted to encode the blue-light-sensing LOV (light, oxygen, or voltage) histidine kinase (LOV-HK) and two red/far-red-light-sensing bacteriophytochromes, BphP1 and BphP2. We provide evidence that LOV-HK and BphP1 form an integrated network that regulates swarming motility in response to multiple light wavelengths. The swarming motility of P. syringae B728a deletion mutants indicated that LOV-HK positively regulates swarming motility in response to blue light and BphP1 negatively regulates swarming motility in response to red and far-red light. BphP2 does not detectably regulate swarming motility. The histidine kinase activity of each LOV-HK and BphP1 is required for this regulation based on the loss of complementation upon mutation of residues key to their kinase activity. Surprisingly, mutants lacking both lov and bphP1 were similar in motility to a bphP1 single mutant in blue light, indicating that the loss of bphP1 is epistatic to the loss of lov and also that BphP1 unexpectedly responds to blue light. Moreover, whereas expression of bphP1 did not alter motility under blue light in a bphP1 mutant, it reduced motility in a mutant lacking lov and bphP1, demonstrating that LOV-HK positively regulates motility by suppressing negative regulation by BphP1. These results are the first to show cross talk between the LOV protein and phytochrome signaling pathways in bacteria, and the similarity of this regulatory network to that of photoreceptors in plants suggests a possible common ancestry. IMPORTANCE Photosensory proteins enable organisms to perceive and respond to light. The biological and ecological roles of these proteins in nonphotosynthetic bacteria are largely unknown. This study discovered that a blue-light-sensing LOV (light, oxygen, or

  6. The Differential Effects of Anesthetics on Bacterial Behaviors

    PubMed Central

    Chamberlain, Matthew; Koutsogiannaki, Sophia; Schaefers, Matthew; Babazada, Hasan; Liu, Renyu; Yuki, Koichi

    2017-01-01

    Volatile anesthetics have been in clinical use for a long period of time and are considered to be promiscuous by presumably interacting with several ion channels in the central nervous system to produce anesthesia. Because ion channels and their existing evolutionary analogues, ion transporters, are very important in various organisms, it is possible that volatile anesthetics may affect some bacteria. In this study, we hypothesized that volatile anesthetics could affect bacterial behaviors. We evaluated the impact of anesthetics on bacterial growth, motility (swimming and gliding) and biofilm formation of four common bacterial pathogens in vitro. We found that commonly used volatile anesthetics isoflurane and sevoflurane affected bacterial motility and biofilm formation without any effect on growth of the common bacterial pathogens studied here. Using available Escherichia coli gene deletion mutants of ion transporters and in silico molecular docking, we suggested that these altered behaviors might be at least partly via the interaction of volatile anesthetics with ion transporters. PMID:28099463

  7. Semiautomated Motility Assay For Determining Toxicity

    NASA Technical Reports Server (NTRS)

    Noever, David A.; Cronise, Raymond

    1996-01-01

    Improved method of assessing toxicities of various substances based on observation of effects of those substances on motilities of manageably small number of cells of protozoan species Tetrahema pyriformis. Provides repeatable, standardized tests with minimal handling by technicians and with minimal exposure of technicians to chemicals. Rapid and economical alternative to Draize test.

  8. Esophageal motility disorders after gastric banding.

    PubMed

    O'Rourke, R W; Deveney, C W; McConnell, D B; Wolfe, B M; Jobe, B A

    2007-01-01

    The long-term effects of gastric banding on esophageal function are not well described. This report describes a 28-year-old woman who developed signs and symptoms of abnormal esophageal motility and lower esophageal sphincter hypotension after gastric banding for morbid obesity. The current literature addressing the effects of gastric banding on esophageal function in light of this case report is discussed.

  9. Esophageal motility abnormalities in gastroesophageal reflux disease.

    PubMed

    Martinucci, Irene; de Bortoli, Nicola; Giacchino, Maria; Bodini, Giorgia; Marabotto, Elisa; Marchi, Santino; Savarino, Vincenzo; Savarino, Edoardo

    2014-05-06

    Esophageal motility abnormalities are among the main factors implicated in the pathogenesis of gastroesophageal reflux disease. The recent introduction in clinical and research practice of novel esophageal testing has markedly improved our understanding of the mechanisms contributing to the development of gastroesophageal reflux disease, allowing a better management of patients with this disorder. In this context, the present article intends to provide an overview of the current literature about esophageal motility dysfunctions in patients with gastroesophageal reflux disease. Esophageal manometry, by recording intraluminal pressure, represents the gold standard to diagnose esophageal motility abnormalities. In particular, using novel techniques, such as high resolution manometry with or without concurrent intraluminal impedance monitoring, transient lower esophageal sphincter (LES) relaxations, hypotensive LES, ineffective esophageal peristalsis and bolus transit abnormalities have been better defined and strongly implicated in gastroesophageal reflux disease development. Overall, recent findings suggest that esophageal motility abnormalities are increasingly prevalent with increasing severity of reflux disease, from non-erosive reflux disease to erosive reflux disease and Barrett's esophagus. Characterizing esophageal dysmotility among different subgroups of patients with reflux disease may represent a fundamental approach to properly diagnose these patients and, thus, to set up the best therapeutic management. Currently, surgery represents the only reliable way to restore the esophagogastric junction integrity and to reduce transient LES relaxations that are considered to be the predominant mechanism by which gastric contents can enter the esophagus. On that ground, more in depth future studies assessing the pathogenetic role of dysmotility in patients with reflux disease are warranted.

  10. [Increased spontaneous uterine motility with serotonin].

    PubMed

    Lechner, W; Sölder, E; Sölder, B; Kölle, D; Huter, O

    1992-01-01

    The influence of serotonine, a vasoactive neurotransmitter, on the spontaneous motility of uterine strips was investigated. A highly significant (p less than 0.001) increase of uterine activity was observed when serotonine 10(-6) M was added to the perfusing medium.

  11. Buoyant plumes from solute gradients generated by non-motile Escherichia coli

    NASA Astrophysics Data System (ADS)

    Benoit, M. R.; Brown, R. B.; Todd, P.; Nelson, E. S.; Klaus, D. M.

    2008-12-01

    The effect of hydrodynamic mixing in bacterial populations due to bacterial chemotaxis is a well-described phenomenon known as bioconvection. Here we report the observation of buoyant plumes that result in hydrodynamic mixing, but in contrast to bioconvection the plumes form in the absence of bacterial motility. We propose that the buoyant flow originates from solute gradients created by bacterial metabolism, similar to solute-induced buoyant flow around growing protein crystals. In our experiments, metabolically-active non-motile Escherichia coli were layered along the bottom of flat-bottomed containers. The E. coli consumed glucose in the medium creating a lighter fluid beneath a heavier fluid. The situation is an example of Rayleigh-Taylor instability, in which a lighter fluid pushes on a heavier one. We developed a numerical model to study the effect of E. coli nutrient consumption and by-product excretion on extracellular solute gradients. The model solutions showed reduced-density fluid along the bottom of the fluid domain leading to buoyant plumes, which were qualitatively similar to the experimental plumes. We also used scaling analyses to study the dependence of plume formation on container size and cell size, and to investigate the effect of reduced gravity, such as the microgravity conditions encountered during spaceflight.

  12. Buoyant plumes from solute gradients generated by non-motile Escherichia coli.

    PubMed

    Benoit, M R; Brown, R B; Todd, P; Nelson, E S; Klaus, D M

    2008-12-10

    The effect of hydrodynamic mixing in bacterial populations due to bacterial chemotaxis is a well-described phenomenon known as bioconvection. Here we report the observation of buoyant plumes that result in hydrodynamic mixing, but in contrast to bioconvection the plumes form in the absence of bacterial motility. We propose that the buoyant flow originates from solute gradients created by bacterial metabolism, similar to solute-induced buoyant flow around growing protein crystals. In our experiments, metabolically-active non-motile Escherichia coli were layered along the bottom of flat-bottomed containers. The E. coli consumed glucose in the medium creating a lighter fluid beneath a heavier fluid. The situation is an example of Rayleigh-Taylor instability, in which a lighter fluid pushes on a heavier one. We developed a numerical model to study the effect of E. coli nutrient consumption and by-product excretion on extracellular solute gradients. The model solutions showed reduced-density fluid along the bottom of the fluid domain leading to buoyant plumes, which were qualitatively similar to the experimental plumes. We also used scaling analyses to study the dependence of plume formation on container size and cell size, and to investigate the effect of reduced gravity, such as the microgravity conditions encountered during spaceflight.

  13. An animated model of reticulorumen motility.

    PubMed

    Gookin, Jody L; Foster, Derek M; Harvey, Alice M; McWhorter, Dan

    2009-01-01

    Understanding reticulorumen motility is important to the assessment of ruminant health and optimal production, and in the recognition, diagnosis, and treatment of disease. Accordingly, the teaching of reticulorumen motility is a staple of all veterinary curricula. This teaching has historically been based on written descriptions, line drawings, or pressure tracings obtained during contraction sequences. We developed an animated model of reticulorumen motility and hypothesized that veterinary students would prefer use of the model over traditional instructional methods. First-year veterinary students were randomly allocated to one of two online learning exercises: with the animated model (Group A) or with text and line drawings (Group B) depicting reticulorumen motility. Learning was assessed with a multiple-choice quiz and feedback on the learning alternatives was obtained by survey. Seventy-four students participated in the study, including 38/42 in Group A and 36/36 in Group B. Sixty-four out of 72 students (89%) responded that they would prefer use of the animated model if only one of the two learning methods was available. A majority of students agreed or strongly agreed that the animated model was easy to understand and improved their knowledge and appreciation of the importance of reticulorumen motility, and would recommend the model to other veterinary students. Interestingly, students in Group B achieved higher scores on examination than students in Group A. This could be speculatively attributed to the inclusion of an itemized list of contraction sequences in the text provided to Group B and failure of Group A students to read the text associated with the animations.

  14. Bacterial Sialidase

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

  15. Host Gut Motility Promotes Competitive Exclusion within a Model Intestinal Microbiota

    PubMed Central

    Baker, Ryan P; Schlomann, Brandon H; Ganz, Julia; Eisen, Judith S; Guillemin, Karen; Parthasarathy, Raghuveer

    2016-01-01

    The gut microbiota is a complex consortium of microorganisms with the ability to influence important aspects of host health and development. Harnessing this “microbial organ” for biomedical applications requires clarifying the degree to which host and bacterial factors act alone or in combination to govern the stability of specific lineages. To address this issue, we combined bacteriological manipulation and light sheet fluorescence microscopy to monitor the dynamics of a defined two-species microbiota within a vertebrate gut. We observed that the interplay between each population and the gut environment produces distinct spatiotemporal patterns. As a consequence, one species dominates while the other experiences sudden drops in abundance that are well fit by a stochastic mathematical model. Modeling revealed that direct bacterial competition could only partially explain the observed phenomena, suggesting that a host factor is also important in shaping the community. We hypothesized the host determinant to be gut motility, and tested this mechanism by measuring colonization in hosts with enteric nervous system dysfunction due to a mutation in the ret locus, which in humans is associated with the intestinal motility disorder known as Hirschsprung disease. In mutant hosts we found reduced gut motility and, confirming our hypothesis, robust coexistence of both bacterial species. This study provides evidence that host-mediated spatial structuring and stochastic perturbation of communities can drive bacterial population dynamics within the gut, and it reveals a new facet of the intestinal host–microbe interface by demonstrating the capacity of the enteric nervous system to influence the microbiota. Ultimately, these findings suggest that therapeutic strategies targeting the intestinal ecosystem should consider the dynamic physical nature of the gut environment. PMID:27458727

  16. [THE EFFECT OF waaL LIGASE GENES DELETION ON MOTILITY AND STRESS ADAPTATION REACTIONS OF YERSINIA ENTEROCOLITICA 6471/76].

    PubMed

    Shevchenko, J I; Shilina, J V; Pozur, V K; Skurnik, M

    2015-01-01

    The aim of current study was to estimate the influence of waaL(OS) and waaL(PS) genes deletion on lipopolysaccharide (LPS) synthesis, bacterial motility and stress resistance of bacteria Yersinia enterocolitica 6471/76. Single and double waaL mutants were created by replacing the wild-type alleles in bacterial chromosome for mutant ones. The phenotypes of mutants were visualized by DOC-PAGE gels stained with silver and immunoblot with specific to O-polysaccharide and outer core monoclonal antibodies. Bacterial motility was evaluated by the diameter of the migration zone. Wild type bacteria and mutants were analyzed by bacterial growth curves in a hypertonic medium. Participation of WaaL ligases in resistance to osmotic pressure was found only in case of both ligese genes deletion. Also the YeO3_os_ps mutants showed motility decreasing, which recovered after adding a functionally active gene. Thus, deletion of both waaL ligase genes lead to a drastic reduction in bacterial motility and increase their sensitivity to hypertonic medium that can indirectly characterize biological role of WaaL ligases.

  17. Esophageal motility disorders in HIV patients.

    PubMed

    Zalar, Alberto E; Olmos, Martín A; Piskorz, Eduardo L; Magnanini, Fernando L

    2003-05-01

    Opportunistic esophageal infections (Candida, cytomegalovirus, herpes simplex virus) and idiophatic esophageal ulcerations are commonly found in HIV patients. However, motility disorders of the esophagus have seldom been investigated in this population. The aim of this prospective study was to determine the presence of motility disorders in HIV patients with esophageal symptoms (with or without associated lesions detected by endoscopy) and in HIV patients without esophageal symptoms and normal esophagoscopy. Eigthteen consecutive HIV patients (10 male, 8 female, ages 20-44 years, mean age 33.5; 8 HIV positive and 10 AIDS) were studied prospectively. Nine patients complained of esophageal symptoms, e.g, dysphagia/odynophagia (group 1) and 9 had symptoms not related to esophageal disease, such as diarrhea, abdominal pain, or gastrointestinal bleeding (group 2). All patients underwent upper endoscopy; mucosal biopsies were taken when macroscopic esophageal lesions were identified or when the patients were symptomatic even if the esophageal mucosa was normal. Esophageal manometry was performed in the 18 patients, using a 4-channel water-perfused system according to a standardized technique. Sixteen of the 18 patients (88.8%) had baseline manometric abnormalities. In group 1, 8/9 patients had esophageal motility disorders: nutcrackeresophagus in 1, hypertensive lower esophageal sphincter (LES) with incomplete relaxation in 2, nonspecific esophageal motility disorders (NEMD) in 3, diffuse esophageal spasm in 1, esophageal hypocontraction with low LES pressure in 1. Six of these 9 patients had lesions detected by endoscopy: CMV ulcers in 2, idiopathic ulcers in 1, candidiasis in 1, idiopathic ulcer + candidiasis in 1, nonspecific esophagitis in 1; and 3/9 had normal endoscopy and normal esophageal biopsies. In group 2, 8/9 patients had abnormal motility: hypertensive LES with incomplete relaxation in 1, nutcracker esophagus in 2, esophageal hypocontraction in 3, and NEMD

  18. Campylobacter jejuni PflB is required for motility and colonisation of the chicken gastrointestinal tract.

    PubMed

    Kanji, Alpa; Jones, Michael A; Maskell, Duncan J; Grant, Andrew J

    2015-12-01

    Campylobacter jejuni is the leading cause of foodborne bacterial gastroenteritis worldwide. Although the mechanisms by which C. jejuni causes disease are not completely understood, the presence of functional flagella appears to be required for colonisation of the gastrointestinal tract of humans and animals. Therefore much attention has been given to understanding the synthesis and role of flagella in C. jejuni. In this study we report insights into the function of PflB that is essential for Campylobacter motility. We have explored the function of this gene by constructing deletion mutants in C. jejuni strains NCTC11168 and M1, in the genes cj0390 and CJM1_0368, respectively. The mutants were non-motile yet assembled flagella that appeared structurally identical to the wild type. Furthermore the protein is required for C. jejuni colonisation of caeca in a two-week old chicken colonisation model.

  19. Micro-motors: A motile bacteria based system for liposome cargo transport

    PubMed Central

    Dogra, Navneet; Izadi, Hadi; Vanderlick, T. Kyle

    2016-01-01

    Biological micro-motors (microorganisms) have potential applications in energy utilization and nanotechnology. However, harnessing the power generated by such motors to execute desired work is extremely difficult. Here, we employ the power of motile bacteria to transport small, large, and giant unilamellar vesicles (SUVs, LUVs, and GUVs). Furthermore, we demonstrate bacteria–bilayer interactions by probing glycolipids inside the model membrane scaffold. Fluorescence Resonance Energy Transfer (FRET) spectroscopic and microscopic methods were utilized for understanding these interactions. We found that motile bacteria could successfully propel SUVs and LUVs with a velocity of 28 μm s−1 and 13 μm s−1, respectively. GUVs, however, displayed Brownian motion and could not be propelled by attached bacteria. Bacterial velocity decreased with the larger loaded cargo, which agrees with our calculations of loaded bacteria swimming at low Reynolds number. PMID:27377152

  20. Pea Broth Enhances the Biocontrol Efficacy of Lysobacter capsici AZ78 by Triggering Cell Motility Associated with Biogenesis of Type IV Pilus

    PubMed Central

    Tomada, Selena; Puopolo, Gerardo; Perazzolli, Michele; Musetti, Rita; Loi, Nazia; Pertot, Ilaria

    2016-01-01

    Bacterial cells can display different types of motility, due to the presence of external appendages such as flagella and type IV pili. To date, little information on the mechanisms involved in the motility of the Lysobacter species has been available. Recently, L. capsici AZ78, a biocontrol agent of phytopathogenic oomycetes, showed the ability to move on jellified pea broth. Pea broth medium improved also the biocontrol activity of L. capsici AZ78 against Plasmopara viticola under greenhouse conditions. Noteworthy, the quantity of pea residues remaining on grapevine leaves fostered cell motility in L. capsici AZ78. Based on these results, this unusual motility related to the composition of the growth medium was investigated in bacterial strains belonging to several Lysobacter species. The six L. capsici strains tested developed dendrite-like colonies when grown on jellified pea broth, while the development of dendrite-like colonies was not recorded in the media commonly used in motility assays. To determine the presence of genes responsible for biogenesis of the flagellum and type IV pili, the genome of L. capsici AZ78 was mined. Genes encoding structural components and regulatory factors of type IV pili were upregulated in L. capsici AZ78 cells grown on the above-mentioned medium, as compared with the other tested media. These results provide new insight into the motility mechanism of L. capsici members and the role of type IV pili and pea compounds on the epiphytic fitness and biocontrol features of L. capsici AZ78. PMID:27507963

  1. Electrical Signaling in Motile and Primary Cilia

    PubMed Central

    Kleene, Steven J.; Van Houten, Judith L.

    2014-01-01

    Cilia are highly conserved for their structure and also for their sensory functions. They serve as antennae for extracellular information. Whether the cilia are motile or not, they respond to environmental mechanical and chemical stimuli and send signals to the cell body. The information from extracellular stimuli is commonly converted to electrical signals through the repertoire of ion-conducting channels in the ciliary membrane, which results in changes in concentrations of ions, especially calcium ions, in the cilia. These changes, in turn, affect motility and the ability of the signaling pathways in the cilia and cell body to carry on the signal transduction. We review here the activities of ion channels in cilia in animals from protists to vertebrates. PMID:25892740

  2. Hydrodynamic Contributions to Amoeboid Cell Motility

    NASA Astrophysics Data System (ADS)

    Lewis, Owen; Guy, Robert

    2012-11-01

    Understanding the methods by which cells move is a fundamental problem in modern biology. Recent evidence has shown that the fluid dynamics of cytoplasm can play a vital role in cellular motility. The slime mold Physarum polycephalum provides an excellent model organism for the study of amoeboid motion. In this research, we use a simply analytic model in conjuction with computational experiments to investigate intracellular fluid flow in a simple model of Physarum. Of particlar interest are stresses generated by cytoplasmic flow which may be used to aid in cellular motility. In our numerical model, the Immersed Boundary Method is used to account for such stresses. We investigate the relationship between contraction waves, flow waves, adhesion, and locomotive forces in an attempt to characterize conditions necessary to generate directed motion.

  3. Hydrodynamic Contributions to Amoeboid Cell Motility

    NASA Astrophysics Data System (ADS)

    Lewis, Owen; Guy, Robert

    2011-11-01

    Understanding the methods by which cells move is a fundamental problem in modern biology. Recent evidence has shown that the fluid dynamics of cytoplasm can play a vital role in cellular motility. The slime mold Physarum polycephalum provides an excellent model organism for the study of amoeboid motion. In this research, we use both analytic and computational models to investigate intracellular fluid flow in a simple model of Physarum. In both models, of we are specifically interested in stresses generated by cytoplasmic flow which act in the direction of cellular motility. In our numerical model, the Immersed Boundary Method is used to account for such stresses. We investigate the relationship between contraction waves, low waves and locomotive forces, and attempt characterize conditions necessary to generate directed motion.

  4. Uterine motility in patients with bicornuate uterus.

    PubMed

    Oliva, G C; Fratoni, A; Genova, M; Romanini, C

    1992-01-01

    This study analyzes uterine motility in 12 women with a bicornuate uterus using the results of the recordings of endo-uterine pressure, obtained with two balloon-closed catheters. Seven patients had symmetric uterine cavities, while the rest (5 patient) had very dissimilar ones. The registration of the uterine motility was carried out during various phases of the cycle and after the administration of two drugs (oxitocin and methylergobasine), with the following results: the bicornuate uterus has a spontaneous activity similar to that of a normal uterus. A similar contractile response was observed in the uteri with two anatomically symmetric horns, whereas a dissimilar response was typical of the uteri with marked anatomic differences between the two horns.

  5. Symbiosis and the origin of eukaryotic motility

    NASA Technical Reports Server (NTRS)

    Margulis, L.; Hinkle, G.

    1991-01-01

    Ongoing work to test the hypothesis of the origin of eukaryotic cell organelles by microbial symbioses is discussed. Because of the widespread acceptance of the serial endosymbiotic theory (SET) of the origin of plastids and mitochondria, the idea of the symbiotic origin of the centrioles and axonemes for spirochete bacteria motility symbiosis was tested. Intracellular microtubular systems are purported to derive from symbiotic associations between ancestral eukaryotic cells and motile bacteria. Four lines of approach to this problem are being pursued: (1) cloning the gene of a tubulin-like protein discovered in Spirocheata bajacaliforniesis; (2) seeking axoneme proteins in spirochets by antibody cross-reaction; (3) attempting to cultivate larger, free-living spirochetes; and (4) studying in detail spirochetes (e.g., Cristispira) symbiotic with marine animals. Other aspects of the investigation are presented.

  6. Endocytic reawakening of motility in jammed epithelia.

    PubMed

    Malinverno, Chiara; Corallino, Salvatore; Giavazzi, Fabio; Bergert, Martin; Li, Qingsen; Leoni, Marco; Disanza, Andrea; Frittoli, Emanuela; Oldani, Amanda; Martini, Emanuele; Lendenmann, Tobias; Deflorian, Gianluca; Beznoussenko, Galina V; Poulikakos, Dimos; Ong, Kok Haur; Uroz, Marina; Trepat, Xavier; Parazzoli, Dario; Maiuri, Paolo; Yu, Weimiao; Ferrari, Aldo; Cerbino, Roberto; Scita, Giorgio

    2017-01-30

    Dynamics of epithelial monolayers has recently been interpreted in terms of a jamming or rigidity transition. How cells control such phase transitions is, however, unknown. Here we show that RAB5A, a key endocytic protein, is sufficient to induce large-scale, coordinated motility over tens of cells, and ballistic motion in otherwise kinetically arrested monolayers. This is linked to increased traction forces and to the extension of cell protrusions, which align with local velocity. Molecularly, impairing endocytosis, macropinocytosis or increasing fluid efflux abrogates RAB5A-induced collective motility. A simple model based on mechanical junctional tension and an active cell reorientation mechanism for the velocity of self-propelled cells identifies regimes of monolayer dynamics that explain endocytic reawakening of locomotion in terms of a combination of large-scale directed migration and local unjamming. These changes in multicellular dynamics enable collectives to migrate under physical constraints and may be exploited by tumours for interstitial dissemination.

  7. Involvement of the Type IX Secretion System in Capnocytophaga ochracea Gliding Motility and Biofilm Formation

    PubMed Central

    Kita, Daichi; Shibata, Satoshi; Kikuchi, Yuichiro; Kokubu, Eitoyo; Nakayama, Koji; Saito, Atsushi

    2016-01-01

    Capnocytophaga ochracea is a Gram-negative, rod-shaped bacterium that demonstrates gliding motility when cultured on solid agar surfaces. C. ochracea possesses the ability to form biofilms; however, factors involved in biofilm formation by this bacterium are unclear. A type IX secretion system (T9SS) in Flavobacterium johnsoniae was shown to be involved in the transport of proteins (e.g., several adhesins) to the cell surface. Genes orthologous to those encoding T9SS proteins in F. johnsoniae have been identified in the genome of C. ochracea; therefore, the T9SS may be involved in biofilm formation by C. ochracea. Here we constructed three ortholog-deficient C. ochracea mutants lacking sprB (which encodes a gliding motility adhesin) or gldK or sprT (which encode T9SS proteins in F. johnsoniae). Gliding motility was lost in each mutant, suggesting that, in C. ochracea, the proteins encoded by sprB, gldK, and sprT are necessary for gliding motility, and SprB is transported to the cell surface by the T9SS. For the ΔgldK, ΔsprT, and ΔsprB strains, the amounts of crystal violet-associated biofilm, relative to wild-type values, were 49%, 34%, and 65%, respectively, at 48 h. Confocal laser scanning and scanning electron microscopy revealed that the biofilms formed by wild-type C. ochracea were denser and bacterial cells were closer together than in those formed by the mutant strains. Together, these results indicate that proteins exported by the T9SS are key elements of the gliding motility and biofilm formation of C. ochracea. PMID:26729712

  8. Cell motility: Combining experiments with modeling

    NASA Astrophysics Data System (ADS)

    Rappel, Wouter-Jan

    2013-03-01

    Cell migration and motility is a pervasive process in many biology systems. It involves intra-cellular signal transduction pathways that eventually lead to membrane extension and contraction. Here we describe our efforts to combine quantitative experiments with theoretical and computational modeling to gain fundamental insights into eukaryotic cell motion. In particular, we will focus on the amoeboid motion of Dictyostelium discoideum cells. This work is supported by the National Institutes of Health (P01 GM078586)

  9. Motility-indole-lysine-sulfide medium.

    PubMed

    Ederer, G M; Lund, M E; Blazevic, D J; Reller, L B; Mirrett, S

    1975-09-01

    A medium designed for the detection of motility, indole, lysine decarboxylase and deaminase reactions, and H2S production was devised and evaluated. Results, using 157 strains of enteric pathogens, were in agreement with reference methods. When 300 isolates from fecal cultures were screened using this medium, Shigella was easily differentiated from Escherichia and more of the Proteus species, especially P. morganii, could be eliminated from further study.

  10. Mouse infection and pathogenesis by Trypanosoma brucei motility mutants.

    PubMed

    Kisalu, Neville K; Langousis, Gerasimos; Bentolila, Laurent A; Ralston, Katherine S; Hill, Kent L

    2014-06-01

    The flagellum of Trypanosoma brucei is an essential and multifunctional organelle that drives parasite motility and is receiving increased attention as a potential drug target. In the mammalian host, parasite motility is suspected to contribute to infection and disease pathogenesis. However, it has not been possible to test this hypothesis owing to lack of motility mutants that are viable in the bloodstream life cycle stage that infects the mammalian host. We recently identified a bloodstream-form motility mutant in 427-derived T. brucei in which point mutations in the LC1 dynein subunit disrupt propulsive motility but do not affect viability. These mutants have an actively beating flagellum, but cannot translocate. Here we demonstrate that the LC1 point mutant fails to show enhanced cell motility upon increasing viscosity of the surrounding medium, which is a hallmark of wild type T. brucei, thus indicating that motility of the mutant is fundamentally altered compared with wild type cells. We next used the LC1 point mutant to assess the influence of trypanosome motility on infection in mice. Wesurprisingly found that disrupting parasite motility has no discernible effect on T. brucei bloodstream infection. Infection time-course, maximum parasitaemia, number of waves of parasitaemia, clinical features and disease outcome are indistinguishable between motility mutant and control parasites. Our studies provide an important step toward understanding the contribution of parasite motility to infection and a foundation for future investigations of T. brucei interaction with the mammalian host.

  11. Hyaluronan stimulates pancreatic cancer cell motility

    PubMed Central

    Cheng, Xiao-Bo; Kohi, Shiro; Koga, Atsuhiro; Hirata, Keiji; Sato, Norihiro

    2016-01-01

    Hyaluronan (HA) accumulates in pancreatic ductal adenocarcinoma (PDAC), but functional significance of HA in the aggressive phenotype remains unknown. We used different models to investigate the effect of HA on PDAC cell motility by wound healing and transwell migration assay. Changes in cell motility were examined in 8 PDAC cell lines in response to inhibition of HA production by treatment with 4-methylumbelliferone (4-MU) and to promotion by treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or by co-culture with tumor-derived stromal fibroblasts. We also investigated changes in cell motility by adding exogenous HA. Additionally, mRNA expressions of hyaluronan synthases and hyaluronidases were examined using real time RT-PCR. Inhibition of HA by 4-MU significantly decreased the migration, whereas promotion of HA by TPA or co-culture with tumor-derived fibroblasts significantly increased the migration of PDAC cells. The changes in HA production by these treatments tended to be associated with changes in HAS3 mRNA expression. Furthermore, addition of exogenous HA, especially low-molecular-weight HA, significantly increased the migration of PDAC cells. These findings suggest that HA stimulates PDAC cell migration and thus represents an ideal therapeutic target to prevent invasion and metastasis. PMID:26684359

  12. Effect of total laryngectomy on esophageal motility

    SciTech Connect

    Hanks, J.B.; Fisher, S.R.; Meyers, W.C.; Christian, K.C.; Postlethwait, R.W.; Jones, R.S.

    1981-01-01

    Total laryngectomy for cancer can result in dysphagia and altered esophageal motility. Manometric changes in the upper esophageal sphincter (UES), and in proximal and distal esophageal function have been reported. However, most studies have failed to take into account radiation therapy and appropriate controls. We selected ten male patients (54.3 +/- 1.9 yr) for longitudinal manometric evaluation prior to laryngectomy then at two weeks and again six months later. No patient received preoperative radiation therapy, had a previous history of esophageal surgery, or developed a postoperative wound infection or fistula. Seven of ten patients had positive nodes and received 6,000-6,600 rads postoperative radiation therapy. Preoperatively 4 of 10 patients complained of dysphagia which did not significantly change following surgery and radiation. Two of three patients who did not complain of dysphagia preoperatively and received radiation postoperatively developed dysphagia. No patient without dysphagia preoperatively who received no radiation therapy developed symptoms. Our studies show that laryngectomy causes alterations in the UES resting and peak pressures but not in the proximal or distal esophagus, or the lower esophageal sphincter. These data also imply radiation therapy may be associated with progressive alterations in motility and symptomatology. Further study regarding the effects of radiation on esophageal motility and function are urged.

  13. Motility of active fluid drops on surfaces

    NASA Astrophysics Data System (ADS)

    Khoromskaia, Diana; Alexander, Gareth P.

    2015-12-01

    Drops of active liquid crystal have recently shown the ability to self-propel, which was associated with topological defects in the orientation of active filaments [Sanchez et al., Nature 491, 431 (2013), 10.1038/nature11591]. Here, we study the onset and different aspects of motility of a three-dimensional drop of active fluid on a planar surface. We analyze theoretically how motility is affected by orientation profiles with defects of various types and locations, by the shape of the drop, and by surface friction at the substrate. In the scope of a thin drop approximation, we derive exact expressions for the flow in the drop that is generated by a given orientation profile. The flow has a natural decomposition into terms that depend entirely on the geometrical properties of the orientation profile, i.e., its bend and splay, and a term coupling the orientation to the shape of the drop. We find that asymmetric splay or bend generates a directed bulk flow and enables the drop to move, with maximal speeds achieved when the splay or bend is induced by a topological defect in the interior of the drop. In motile drops the direction and speed of self-propulsion is controlled by friction at the substrate.

  14. Gastrointestinal motility testing--a personal perspective.

    PubMed

    Quigley, E M

    1995-01-01

    The role of motility tests in the evaluation of some common disorders in which motility has been assumed to play a role is reviewed. Three separate areas, non-cardiac chest pain, constipation and the irritable bowel syndrome are discussed. In each area, considerable difficulty in the clinical definition of these disorders persists and presents a major obstacle to the evaluation of diagnostic tests. With regard to non-cardiac chest pain, it is apparent that gastro-oesophageal reflux and sensory/perception abnormalities, rather than dysmotility, are the predominant factors, and investigations should take account of this. While studies of colonic and small intestinal motility have demonstrated various abnormal patterns in patients described as suffering from the irritable bowel syndrome, the specificity of any of these motor 'abnormalities' remains uncertain, and manometry cannot be recommended as a diagnostic tool in this context. Considerable advances have been made in our understanding of gut motor physiology and in our ability to accurately record motor function in man, the basic pathophysiology of many 'functional' gut syndromes remains unclear, and the role of dysmotility, in particular, poorly defined.

  15. FleQ Coordinates Flagellum-Dependent and -Independent Motilities in Pseudomonas syringae pv. tomato DC3000

    PubMed Central

    Nogales, Joaquina; Vargas, Paola; Farias, Gabriela A.; Olmedilla, Adela; Sanjuán, Juan

    2015-01-01

    Motility plays an essential role in bacterial fitness and colonization in the plant environment, since it favors nutrient acquisition and avoidance of toxic substances, successful competition with other microorganisms, the ability to locate the preferred hosts, access to optimal sites within them, and dispersal in the environment during the course of transmission. In this work, we have observed that the mutation of the flagellar master regulatory gene, fleQ, alters bacterial surface motility and biosurfactant production, uncovering a new type of motility for Pseudomonas syringae pv. tomato DC3000 on semisolid surfaces. We present evidence that P. syringae pv. tomato DC3000 moves over semisolid surfaces by using at least two different types of motility, namely, swarming, which depends on the presence of flagella and syringafactin, a biosurfactant produced by this strain, and a flagellum-independent surface spreading or sliding, which also requires syringafactin. We also show that FleQ activates flagellum synthesis and negatively regulates syringafactin production in P. syringae pv. tomato DC3000. Finally, it was surprising to observe that mutants lacking flagella or syringafactin were as virulent as the wild type, and only the simultaneous loss of both flagella and syringafactin impairs the ability of P. syringae pv. tomato DC3000 to colonize tomato host plants and cause disease. PMID:26296726

  16. A Submersible, Off-Axis Holographic Microscope for Detection of Microbial Motility and Morphology in Aqueous and Icy Environments.

    PubMed

    Lindensmith, Christian A; Rider, Stephanie; Bedrossian, Manuel; Wallace, J Kent; Serabyn, Eugene; Showalter, G Max; Deming, Jody W; Nadeau, Jay L

    2016-01-01

    Sea ice is an analog environment for several of astrobiology's near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM) that is capable of resolving individual bacterial cells, and demonstrated its utility for immediately imaging samples taken directly from sea ice at several locations near Nuuk, Greenland. In all samples, the appearance and motility of eukaryotes were conclusive signs of life. The appearance of prokaryotic cells alone was not sufficient to confirm life, but when prokaryotic motility occurred, it was rapid and conclusive. Warming the samples to above-freezing temperatures or supplementing with serine increased the number of motile cells and the speed of motility; supplementing with serine also stimulated chemotaxis. These results show that DHM is a useful technique for detection of active organisms in extreme environments, and that motility may be used as a biosignature in the liquid brines that persist in ice. These findings have important implications for the design of missions to icy environments and suggest ways in which DHM imaging may be integrated with chemical life-detection suites in order to create more conclusive life detection packages.

  17. A Submersible, Off-Axis Holographic Microscope for Detection of Microbial Motility and Morphology in Aqueous and Icy Environments

    PubMed Central

    Lindensmith, Christian A.; Rider, Stephanie; Bedrossian, Manuel; Wallace, J. Kent; Serabyn, Eugene; Showalter, G. Max; Deming, Jody W.; Nadeau, Jay L.

    2016-01-01

    Sea ice is an analog environment for several of astrobiology’s near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM) that is capable of resolving individual bacterial cells, and demonstrated its utility for immediately imaging samples taken directly from sea ice at several locations near Nuuk, Greenland. In all samples, the appearance and motility of eukaryotes were conclusive signs of life. The appearance of prokaryotic cells alone was not sufficient to confirm life, but when prokaryotic motility occurred, it was rapid and conclusive. Warming the samples to above-freezing temperatures or supplementing with serine increased the number of motile cells and the speed of motility; supplementing with serine also stimulated chemotaxis. These results show that DHM is a useful technique for detection of active organisms in extreme environments, and that motility may be used as a biosignature in the liquid brines that persist in ice. These findings have important implications for the design of missions to icy environments and suggest ways in which DHM imaging may be integrated with chemical life-detection suites in order to create more conclusive life detection packages. PMID:26812683

  18. Physics of protein motility and motor proteins

    NASA Astrophysics Data System (ADS)

    Kolomeisky, Anatoly B.

    2013-09-01

    Motor proteins are enzymatic molecules that transform chemical energy into mechanical motion and work. They are critically important for supporting various cellular activities and functions. In the last 15 years significant progress in understanding the functioning of motor proteins has been achieved due to revolutionary breakthroughs in single-molecule experimental techniques and strong advances in theoretical modelling. However, microscopic mechanisms of protein motility are still not well explained, and the collective efforts of many scientists are needed in order to solve these complex problems. In this special section the reader will find the latest advances on the difficult road to mapping motor proteins dynamics in various systems. Recent experimental developments have allowed researchers to monitor and to influence the activity of single motor proteins with a high spatial and temporal resolution. It has stimulated significant theoretical efforts to understand the non-equilibrium nature of protein motility phenomena. The latest results from all these advances are presented and discussed in this special section. We would like to thank the scientists from all over the world who have reported their latest research results for this special section. We are also grateful to the staff and editors of Journal of Physics: Condensed Matter for their invaluable help in handling all the administrative and refereeing activities. The field of motor proteins and protein motility is fast moving, and we hope that this collection of articles will be a useful source of information in this highly interdisciplinary area. Physics of protein motility and motor proteins contents Physics of protein motility and motor proteinsAnatoly B Kolomeisky Identification of unique interactions between the flexible linker and the RecA-like domains of DEAD-box helicase Mss116 Yuan Zhang, Mirkó Palla, Andrew Sun and Jung-Chi Liao The load dependence of the physical properties of a molecular motor

  19. Analysis of bacterial chemotactic response using dynamic laser speckle

    NASA Astrophysics Data System (ADS)

    Murialdo, Silvia E.; Sendra, Gonzalo H.; Passoni, Lucía I.; Arizaga, Ricardo; Gonzalez, J. Froilán; Rabal, Héctor; Trivi, Marcelo

    2009-11-01

    Chemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle (or biospeckle) to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis.

  20. The Wireless Motility Capsule: a One-Stop Shop for the Evaluation of GI Motility Disorders.

    PubMed

    Saad, Richard J

    2016-03-01

    The wireless motility and pH capsule (WMC) provides an office-based test to simultaneously assess both regional and whole gut transit. Ingestion of this non-digestible capsule capable of measuring temperature, pH, and the pressure of its immediate surroundings allows for the measurement of gastric, small bowel, and colonic transit times in an ambulatory setting. Approved by the US Food and Drug Administration for the evaluation of suspected conditions of delayed gastric emptying and the evaluation of colonic transit in chronic idiopathic constipation, WMC should be considered in suspected gastrointestinal motility disorders as it provides a single study capable of simultaneously assessing for regional, multiregional, or generalized motility disorders. Specific indications for testing with the WMC should include the evaluation of suspect cases of gastroparesis, small bowel dysmotility, and slow transit constipation, as well as symptom syndromes suggestive of a multiregional or generalized gastrointestinal transit delay.

  1. Bacterial Chemotaxis: The Early Years of Molecular Studies

    PubMed Central

    Hazelbauer, Gerald L.

    2014-01-01

    This review focuses on the early years of molecular studies of bacterial chemotaxis and motility, beginning in the 1960s with Julius Adler's pioneering work. It describes key observations that established the field and made bacterial chemotaxis a paradigm for the molecular understanding of biological signaling. Consideration of those early years includes aspects of science seldom described in journals: the accidental findings, personal interactions, and scientific culture that often drive scientific progress. PMID:22994495

  2. First identification of proteins involved in motility of Mycoplasma gallisepticum.

    PubMed

    Indikova, Ivana; Vronka, Martin; Szostak, Michael P

    2014-10-17

    Mycoplasma gallisepticum, the most pathogenic mycoplasma in poultry, is able to glide over solid surfaces. Although this gliding motility was first observed in 1968, no specific protein has yet been shown to be involved in gliding. We examined M. gallisepticum strains and clonal variants for motility and found that the cytadherence proteins GapA and CrmA were required for gliding. Loss of GapA or CrmA resulted in the loss of motility and hemadsorption and led to drastic changes in the characteristic flask-shape of the cells. To identify further genes involved in motility, a transposon mutant library of M. gallisepticum was generated and screened for motility-deficient mutants, using a screening assay based on colony morphology. Motility-deficient mutants had transposon insertions in gapA and the neighbouring downstream gene crmA. In addition, insertions were seen in gene mgc2, immediately upstream of gapA, in two motility-deficient mutants. In contrast to the GapA/CrmA mutants, the mgc2 motility mutants still possessed the ability to hemadsorb. Complementation of these mutants with a mgc2-hexahistidine fusion gene restored the motile phenotype. This is the first report assigning specific M. gallisepticum proteins to involvement in gliding motility.

  3. Formation and dissolution of bacterial colonies.

    PubMed

    Weber, Christoph A; Lin, Yen Ting; Biais, Nicolas; Zaburdaev, Vasily

    2015-09-01

    Many organisms form colonies for a transient period of time to withstand environmental pressure. Bacterial biofilms are a prototypical example of such behavior. Despite significant interest across disciplines, physical mechanisms governing the formation and dissolution of bacterial colonies are still poorly understood. Starting from a kinetic description of motile and interacting cells we derive a hydrodynamic equation for their density on a surface, where most of the kinetic coefficients are estimated from experimental data for N. gonorrhoeae bacteria. We use it to describe the formation of multiple colonies with sizes consistent with experimental observations. Finally, we show how the changes in the cell-to-cell interactions lead to the dissolution of the bacterial colonies. The successful application of kinetic theory to a complex far from equilibrium system such as formation and dissolution of living bacterial colonies potentially paves the way for the physical quantification of the initial stages of biofilm formation.

  4. Formation and dissolution of bacterial colonies

    NASA Astrophysics Data System (ADS)

    Weber, Christoph A.; Lin, Yen Ting; Biais, Nicolas; Zaburdaev, Vasily

    2015-09-01

    Many organisms form colonies for a transient period of time to withstand environmental pressure. Bacterial biofilms are a prototypical example of such behavior. Despite significant interest across disciplines, physical mechanisms governing the formation and dissolution of bacterial colonies are still poorly understood. Starting from a kinetic description of motile and interacting cells we derive a hydrodynamic equation for their density on a surface, where most of the kinetic coefficients are estimated from experimental data for N. gonorrhoeae bacteria. We use it to describe the formation of multiple colonies with sizes consistent with experimental observations. Finally, we show how the changes in the cell-to-cell interactions lead to the dissolution of the bacterial colonies. The successful application of kinetic theory to a complex far from equilibrium system such as formation and dissolution of living bacterial colonies potentially paves the way for the physical quantification of the initial stages of biofilm formation.

  5. Novel ultrastructures of Treponema primitia and their implications for motility

    PubMed Central

    Murphy, Gavin E.; Matson, Eric G.; Leadbetter, Jared R.; Berg, Howard C.; Jensen, Grant J.

    2011-01-01

    Summary Members of the bacterial phylum Spirochaetes are generally helical cells propelled by periplasmic flagella. The spirochete Treponema primitia is interesting because of its mutualistic role in the termite gut, where it is believed to cooperate with protozoa that break down cellulose and produce H2 as a by-product. Here we report the ultrastructure of T. primitia as obtained by electron cryotomography of intact, frozen-hydrated cells. Several previously unrecognized external structures were revealed, including bowl-like objects decorating the outer membrane, arcades of hook-shaped proteins winding along the exterior and tufts of fibrils extending from the cell tips. Inside the periplasm, cone-like structures were found at each pole. Instead of the single peptidoglycan layer typical of other Gram-negative bacteria, two distinct periplasmic layers were observed. These layers formed a central open space that contained two flagella situated adjacent to each other. In some areas, the inner membrane formed flattened invaginations that protruded into the cytoplasm. High-speed light microscopic images of swimming T. primitia cells showed that cell bodies remained rigid and moved in a helical rather than planar motion. Together, these findings support the ‘rolling cylinder’ model for T. primitia motility that posits rotation of the protoplasmic cylinder within the outer sheath. PMID:18248579

  6. Influence of Helical Cell Shape on Motility of Helicobacter Pylori

    NASA Astrophysics Data System (ADS)

    Hardcastle, Joseph; Martinez, Laura; Salama, Nina; Bansil, Rama; Boston University Collaboration; University of Washington Collaboration

    2014-03-01

    Bacteria's body shape plays an important role in motility by effecting chemotaxis, swimming mechanisms, and swimming speed. A prime example of this is the bacteria Helicobacter Pylori;whose helical shape has long been believed to provide an advantage in penetrating the viscous mucus layer protecting the stomach lining, its niche environment. To explore this we have performed bacteria tracking experiments of both wild-type bacteria along with mutants, which have a straight rod shape. A wide distribution of speeds was found. This distribution reflects both a result of temporal variation in speed and different shape morphologies in the bacterial population. Our results show that body shape plays less role in a simple fluid. However, in a more viscous solution the helical shape results in increased swimming speeds. In addition, we use experimentally obtained cell shape measurements to model the hydrodynamic influence of cell shape on swimming speed using resistive force theory. The results agree with the experiment, especially when we fold in the temporal distribution. Interestingly, our results suggest distinct wild-type subpopulations with varying number of half helices can lead to different swimming speeds. NSF PHY

  7. Microbial Small Talk: Volatiles in Fungal–Bacterial Interactions

    PubMed Central

    Schmidt, Ruth; Etalo, Desalegn W.; de Jager, Victor; Gerards, Saskia; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2016-01-01

    There is increasing evidence that volatile organic compounds (VOCs) play an important role in the interactions between fungi and bacteria, two major groups of soil inhabiting microorganisms. Yet, most of the research has been focused on effects of bacterial volatiles on suppression of plant pathogenic fungi whereas little is known about the responses of bacteria to fungal volatiles. In the current study we performed a metabolomics analysis of volatiles emitted by several fungal and oomycetal soil strains under different nutrient conditions and growth stages. The metabolomics analysis of the tested fungal and oomycetal strains revealed different volatile profiles dependent on the age of the strains and nutrient conditions. Furthermore, we screened the phenotypic responses of soil bacterial strains to volatiles emitted by fungi. Two bacteria, Collimonas pratensis Ter291 and Serratia plymuthica PRI-2C, showed significant changes in their motility, in particular to volatiles emitted by Fusarium culmorum. This fungus produced a unique volatile blend, including several terpenes. Four of these terpenes were selected for further tests to investigate if they influence bacterial motility. Indeed, these terpenes induced or reduced swimming and swarming motility of S. plymuthica PRI-2C and swarming motility of C. pratensis Ter291, partly in a concentration-dependent manner. Overall the results of this work revealed that bacteria are able to sense and respond to fungal volatiles giving further evidence to the suggested importance of volatiles as signaling molecules in fungal–bacterial interactions. PMID:26779150

  8. Cell motility and local viscoelasticity of fibroblasts.

    PubMed

    Park, S; Koch, D; Cardenas, R; Käs, J; Shih, C K

    2005-12-01

    Viscoelastic changes of the lamellipodial actin cytoskeleton are a fundamental element of cell motility. Thus, the correlation between the local viscoelastic properties of the lamellipodium (including the transitional region to the cell body) and the speed of lamellipodial extension is studied for normal and malignantly transformed fibroblasts. Using our atomic force microscopy-based microrheology technique, we found different mechanical properties between the lamellipodia of malignantly transformed fibroblasts (H-ras transformed and SV-T2 fibroblasts) and normal fibroblasts (BALB 3T3 fibroblasts). The average elastic constants, K, in the leading edge of SV-T2 fibroblasts (0.48 +/- 0.51 kPa) and of H-ras transformed fibroblasts (0.42 +/- 0.35 kPa) are significantly lower than that of BALB 3T3 fibroblasts (1.01 +/- 0.40 kPa). The analysis of time-lapse phase contrast images shows that the decrease in the elastic constant, K, for malignantly transformed fibroblasts is correlated with the enhanced motility of the lamellipodium. The measured mean speeds are 6.1 +/- 4.5 microm/h for BALB 3T3 fibroblasts, 13.1 +/- 5.2 microm/h for SV-T2 fibroblasts, and 26.2 +/- 11.5 microm/h for H-ras fibroblasts. Furthermore, the elastic constant, K, increases toward the cell body in many instances which coincide with an increase in actin filament density toward the cell body. The correlation between the enhanced motility and the decrease in viscoelastic moduli supports the Elastic Brownian Ratchet model for driving lamellipodia extension.

  9. Dynamic Clustering in Suspension of Motile Bacteria

    NASA Astrophysics Data System (ADS)

    Zhang, Hepeng; Chen, Xiao; Yang, Xiang; Yang, Mingcheng

    2015-03-01

    Bacteria suspension exhibits a wide range of collective phenomena arising from interactions between individual cells. Here we investigate dynamic clusters of motile bacteria near an air-liquid interface. Cell in a cluster orient its flagella perpendicular to the interface and generate attractive radial fluid flow that leads to cluster formation. Rotating cell also creates tangential forces on neighbors that sets clusters into counter-clockwise rotation. We construct a numerical model of self-propelled particles that interact via pair-wise forces extracted from hydrodynamic calculations; such a model reproduces many properties of observed cluster dynamics.

  10. Gastrointestinal motility in space motion sickness

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Linder, Barry J.; Moore, Thomas P.; Pool, Sam L.

    1987-01-01

    Gastrointestinal symptoms in space motion sickness (SMS) are significantly different from those in ordinary motion sickness (MS). Recording and tabulation of sounds was the only technique that could be used as a measure of motility during spaceflight operations. There were 17 subjects, six unaffected by SMS, who made ambulatory recordings preflight and inflight. With one exception, all those affected had sharply reduced sounds, while those unaffected had increases or moderate reductions. The mechanism of vomiting in SMS appears to be secondary to this ileus, in contrast to vomiting in ordinary MS, where the emesis center is thought to be directly triggered by the vestibular system.

  11. The unique paradigm of spirochete motility and chemotaxis.

    PubMed

    Charon, Nyles W; Cockburn, Andrew; Li, Chunhao; Liu, Jun; Miller, Kelly A; Miller, Michael R; Motaleb, Md A; Wolgemuth, Charles W

    2012-01-01

    Spirochete motility is enigmatic: It differs from the motility of most other bacteria in that the entire bacterium is involved in translocation in the absence of external appendages. Using the Lyme disease spirochete Borrelia burgdorferi (Bb) as a model system, we explore the current research on spirochete motility and chemotaxis. Bb has periplasmic flagella (PFs) subterminally attached to each end of the protoplasmic cell cylinder, and surrounding the cell is an outer membrane. These internal helix-shaped PFs allow the spirochete to swim by generating backward-moving waves by rotation. Exciting advances using cryoelectron tomography are presented with respect to in situ analysis of cell, PF, and motor structure. In addition, advances in the dynamics of motility, chemotaxis, gene regulation, and the role of motility and chemotaxis in the life cycle of Bb are summarized. The results indicate that the motility paradigms of flagellated bacteria do not apply to these unique bacteria.

  12. Swimming and swarming motility properties of peanut-nodulating rhizobia.

    PubMed

    Vicario, Julio C; Dardanelli, Marta S; Giordano, Walter

    2015-01-01

    Motility allows populations of bacteria to rapidly reach and colonize new microniches or microhabitats. The motility of rhizobia (symbiotic nitrogen-fixing bacteria that nodulate legume roots) is an important factor determining their competitive success. We evaluated the effects of temperature, incubation time, and seed exudates on swimming and swarming motility of five strains of Bradyrhizobium sp. (peanut-nodulating rhizobia). Swimming motility was increased by exudate exposure for all strains except native Pc34. In contrast, swarming motility was increased by exudate exposure for native 15A but unchanged for the other four strains. All five strains displayed the ability to differentiate into swarm cells. Morphological examination by scanning electron microscopy showed that the length of the swarm cells was variable, but generally greater than that of vegetative cells. Our findings suggest the importance of differential motility properties of peanut-nodulating rhizobial strains during agricultural inoculation and early steps of symbiotic interaction with the host.

  13. Transposon mutagenesis of Campylobacter jejuni identifies a bipartite energy taxis system required for motility.

    PubMed

    Hendrixson, D R; Akerley, B J; DiRita, V J

    2001-04-01

    Campylobacter jejuni constitutes the leading cause of bacterial gastroenteritis in the United States and a major cause of diarrhoea worldwide. Little is known about virulence mechanisms in this organism because of the scarcity of suitable genetic tools. We have developed an efficient system of in vitro transposon mutagenesis using a mariner-based transposon and purified mariner transposase. Through in vitro transposition of C. jejuni chromosomal DNA followed by natural transformation of the transposed DNA, large random transposon mutant libraries consisting of approximately 16 000 individual mutants were generated. The first genetic screen of C. jejuni using a transposon-generated mutant library identified 28 mutants defective for flagellar motility, one of the few known virulence determinants of this pathogen. We developed a second genetic system, which allows for the construction of defined chromosomal deletions in C. jejuni, and demonstrated the requirement of sigma28 and sigma54 for motility. In addition, we show that sigma28 is involved in the transcription of flaA and that sigma54 is required for transcription of three other flagellar genes, flaB and flgDE. We also identified two previously uncharacterized genes required for motility encoding proteins that we call CetA and CetB, which mediate energy taxis responses. Through our analysis of the Cet proteins, we propose a unique mechanism for sensing energy levels and mediating energy taxis in C. jejuni.

  14. A novel multigene cloning method for the production of a motile ATPase.

    PubMed

    Jang, Min Su; Song, Woo Chul; Shin, Seung Won; Park, Kyung Soo; Kim, Jinseok; Kim, Dong-Ik; Kim, Byung Woo; Um, Soong Ho

    2015-08-10

    With the advent of nanotechnology, new functional modules (e.g., nanomotors, nanoprobes) have become essential in several medical fields. Generally, mechanical modulators systems are the principal components of most cutting-edge technologies in modern biomedical applications. However, the in vivo use of motile probes has raised many concerns due to their low sensitivity and non-biocompatibility. As an alternative, biological enzymatic engines have received increased attention. In particular, ATPases, which belong to a class of motile enzymes that catalyze chemical metabolic reactions, have emerged as a promising motor due to their improved biocompatibility and performance. However, ATPases usually suffer from lower functional activity and are difficult to express recombinantly in bacteria relative to their conventional and synthetic competitors. Here, we report a novel functional modified ATPase with both a simple purification protocol and enhanced motile activity. For this mutant ATPase, a new bacterial subcloning method was established. The ATPase-encoding sequence was redesigned so that the mutant ATPase could be easily produced in an Escherichia coli system. The modified thermophilic F1-ATPase (mTF1-ATPase) demonstrated 17.8unit/mg ATPase activity. We propose that derivatives of our ATPase may enable the development of novel in vitro and in vivo synthetic medical diagnostics, as well as therapeutics.

  15. Complex regulatory network encompassing the Csr, c-di-GMP and motility systems of Salmonella Typhimurium.

    PubMed

    Jonas, Kristina; Edwards, Adrianne N; Ahmad, Irfan; Romeo, Tony; Römling, Ute; Melefors, Ojar

    2010-02-01

    Bacterial survival depends on the ability to switch between sessile and motile lifestyles in response to changing environmental conditions. In many species, this switch is governed by (3'-5')-cyclic-diguanosine monophosphate (c-di-GMP), a signalling molecule, which is metabolized by proteins containing GGDEF and/or EAL domains. Salmonella Typhimurium contains 20 such proteins. Here, we show that the RNA-binding protein CsrA regulates the expression of eight genes encoding GGDEF, GGDEF-EAL and EAL domain proteins. CsrA bound directly to the mRNA leaders of five of these genes, suggesting that it may regulate these genes post-transcriptionally. The c-di-GMP-specific phosphodiesterase STM3611, which reciprocally controls flagella function and production of biofilm matrix components, was regulated by CsrA binding to the mRNA, but was also indirectly regulated by CsrA through the FlhDC/FliA flagella cascade and STM1344. STM1344 is an unconventional (c-di-GMP-inactive) EAL domain protein, recently identified as a negative regulator of flagella gene expression. Here, we demonstrate that CsrA directly downregulates expression of STM1344, which in turn regulates STM3611 through fliA and thus reciprocally controls motility and biofilm factors. Altogether, our data reveal that the concerted and complex regulation of several genes encoding GGDEF/EAL domain proteins allows CsrA to control the motility-sessility switch in S. Typhimurium at multiple levels.

  16. Subinhibitory Concentrations of Allicin Decrease Uropathogenic Escherichia coli (UPEC) Biofilm Formation, Adhesion Ability, and Swimming Motility.

    PubMed

    Yang, Xiaolong; Sha, Kaihui; Xu, Guangya; Tian, Hanwen; Wang, Xiaoying; Chen, Shanze; Wang, Yi; Li, Jingyu; Chen, Junli; Huang, Ning

    2016-06-29

    Uropathogenic Escherichia coli (UPEC) biofilm formation enables the organism to avoid the host immune system, resist antibiotics, and provide a reservoir for persistent infection. Once the biofilm is established, eradication of the infection becomes difficult. Therefore, strategies against UPEC biofilm are urgently required. In this study, we investigated the effect of allicin, isolated from garlic essential oil, on UPEC CFT073 and J96 biofilm formation and dispersal, along with its effect on UPEC adhesion ability and swimming motility. Sub-inhibitory concentrations (sub-MICs) of allicin decreased UPEC biofilm formation and affected its architecture. Allicin was also capable of dispersing biofilm. Furthermore, allicin decreased the bacterial adhesion ability and swimming motility, which are important for biofilm formation. Real-time quantitative polymerase chain reaction (RT-qPCR) revealed that allicin decreased the expression of UPEC type 1 fimbriae adhesin gene fimH. Docking studies suggested that allicin was located within the binding pocket of heptyl α-d-mannopyrannoside in FimH and formed hydrogen bonds with Phe1 and Asn135. In addition, allicin decreased the expression of the two-component regulatory systems (TCSs) cognate response regulator gene uvrY and increased the expression of the RNA binding global regulatory protein gene csrA of UPEC CFT073, which is associated with UPEC biofilm. The findings suggest that sub-MICs of allicin are capable of affecting UPEC biofilm formation and dispersal, and decreasing UPEC adhesion ability and swimming motility.

  17. Subinhibitory Concentrations of Allicin Decrease Uropathogenic Escherichia coli (UPEC) Biofilm Formation, Adhesion Ability, and Swimming Motility

    PubMed Central

    Yang, Xiaolong; Sha, Kaihui; Xu, Guangya; Tian, Hanwen; Wang, Xiaoying; Chen, Shanze; Wang, Yi; Li, Jingyu; Chen, Junli; Huang, Ning

    2016-01-01

    Uropathogenic Escherichia coli (UPEC) biofilm formation enables the organism to avoid the host immune system, resist antibiotics, and provide a reservoir for persistent infection. Once the biofilm is established, eradication of the infection becomes difficult. Therefore, strategies against UPEC biofilm are urgently required. In this study, we investigated the effect of allicin, isolated from garlic essential oil, on UPEC CFT073 and J96 biofilm formation and dispersal, along with its effect on UPEC adhesion ability and swimming motility. Sub-inhibitory concentrations (sub-MICs) of allicin decreased UPEC biofilm formation and affected its architecture. Allicin was also capable of dispersing biofilm. Furthermore, allicin decreased the bacterial adhesion ability and swimming motility, which are important for biofilm formation. Real-time quantitative polymerase chain reaction (RT-qPCR) revealed that allicin decreased the expression of UPEC type 1 fimbriae adhesin gene fimH. Docking studies suggested that allicin was located within the binding pocket of heptyl α-d-mannopyrannoside in FimH and formed hydrogen bonds with Phe1 and Asn135. In addition, allicin decreased the expression of the two-component regulatory systems (TCSs) cognate response regulator gene uvrY and increased the expression of the RNA binding global regulatory protein gene csrA of UPEC CFT073, which is associated with UPEC biofilm. The findings suggest that sub-MICs of allicin are capable of affecting UPEC biofilm formation and dispersal, and decreasing UPEC adhesion ability and swimming motility. PMID:27367677

  18. Ineffective esophageal motility is a primary motility disorder in gastroesophageal reflux disease.

    PubMed

    Ho, Shih-Chi; Chang, Chi-Sen; Wu, Chun-Ying; Chen, Gran-Hum

    2002-03-01

    The relationship between esophageal motor abnormalities and GERD has been widely studied. The purpose of this study was to identify the prevalence of ineffective esophageal motility (IEM) in patients with GERD. In addition, we also evaluated esophageal acid exposure, acid clearance, and endoscopic esophagitis in GERD patients with IEM. Of 89 patients enrolled in this study, 47 (52.8%) were found to have nonspecific esophageal motility disorder (NEMD). Forty-four of the 47 (93.6%) patients with NEMD met the diagnostic criteria for IEM. The overall incidence of IEM in GERD patients was 49.4%. Patients with IEM had significant increases in upright and recumbent mean fraction of time pH < 4 (6.70% and 4.38%) and mean recumbent esophageal acid clearance (12.45 min/reflux) when compared to those with other motility findings. Seventeen of the 44 (39%) IEM patients did not have endoscopic esophagitis. On the other hand, 26 of the 39 (67%) patients with normal manometry had endoscopic esophagitis. We concluded that not only is the prevalence of IEM high in GERD, but also that IEM patients have more recumbent gastroesophageal reflux and delayed acid clearance. Combined with endoscopic findings, we propose that IEM can be viewed as a specific entity of primary esophageal motility disorder in patients with GERD.

  19. Chemokinetic motility responses of the cyanobacterium oscillatoria terebriformis

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Castenholz, Richard W.

    1989-01-01

    Oscillatoria terebriformis, a gliding, filamentous, thermophilic cyanobacterium, exhibited an inhibition of gliding motility upon exposure to fructose. The observed response was transient, and the duration of nonmotility was directly proportional to the concentration of fructose. Upon resumption of motility, the rate of motility was also inversely proportional to the concentration of fructose. Sulfide caused a similar response. The effect of sulfide was specific and not due to either anoxia or negative redox potential. Exposure to glucose, acetate, lactate, or mat interstitial water did not elicit any motility response.

  20. Enhanced motility of a Proteus mirabilis strain expressing hybrid FlaAB flagella.

    PubMed

    Manos, Jim; Artimovich, Elena; Belas, Robert

    2004-05-01

    Proteus mirabilis has two tandemly arranged flagellin-encoding genes, flaA and flaB. flaA is transcribed from a sigma(28) promoter, while flaB is silent. flaA and flaB can undergo reversible rearrangement to produce a set of hybrid genes referred to as flaAB. Flagellins composed of FlaAB protein have a different amino acid sequence and are antigenically distinct from flagellin composed of FlaA, implicating flagellin gene conversion as a putative virulence mechanism for P. mirabilis. The change in amino acid sequence is also hypothesized to alter the filament helix and, hence, affect the motility of FlaAB-expressing strains. To test this hypothesis, the motility of wild-type P. mirabilis was compared with that of a strain, DF1003, locked into the FlaAB(+) hybrid phase, under conditions of altered ionic strength, pH and viscosity. Cell motion tracking analysis showed that DF1003 has wild-type swimming velocity at physiological conditions, but moves significantly faster and travels further compared to the wild-type at NaCl concentrations greater than 170 mM. DF1003 is also significantly faster than the wild-type at pH 5.2, 5.8 and 8.2, and at 5 and 10 % polyvinylpyrrolidone. Measurements of amplitude and wavelength for isolated flagella subjected to pH 5.8 or 425 mM NaCl showed a loss of helical structure in FlaA flagella compared to FlaAB filaments, a feature that could significantly affect motility under these conditions. These results support a hypothesis that FlaAB flagellin imparts a motile advantage to P. mirabilis in conditions that otherwise may impede bacterial movement. In a broader context, flagellar antigenic variation, commonly thought to serve as means to avoid host defences, may also enhance motility in other bacterial species, thus aiding in the adaptation and survival of the cells.

  1. Bacterial Tracheitis

    MedlinePlus

    ... as a complication of croup (see Croup ) or endotracheal intubation (insertion of a plastic breathing tube through the ... irregularities that distinguish bacterial tracheitis from croup. Treatment Endotracheal intubation Antibiotics With treatment, most children recover completely. Very ...

  2. Rational pharmacotherapy of gastrointestinal motility disorders.

    PubMed

    Demol, P; Ruoff, H J; Weihrauch, T R

    1989-04-01

    Nervous control of gastrointestinal motility is extremely complex, is regulated by the enteric system, the "brain of the gut", and modulated by extrinsic nerves. This system with its multiplicity of transmitters and receptors does not always allow a clear interpretation of experimental data, especially with compounds lacking specificity. In this review the complex situation is described particularly in relation to receptor populations (cholinergic, adrenergic, dopamine, histamine, 5-hydroxytryptamine, opioid, gamma-aminobutyric acid (GABA), prostanoid and dihydropyridine receptors), therapeutic aspects of drugs and their usefulness in children. Newer principles with known drugs and promising new compounds with a more appropriate kinetic or fewer side-effects, deriving from distinct pharmacological groups, as candidates for the treatment of gastrointestinal disorders are considered e.g. anticholinergics (prifinium or actilonium bromide), adrenergic alpha 2-agonists (clonidine, lidamidine) for diarrhoea in diabetic neuropathy, adrenergic beta-blockers for shortening postoperative ileus (propranolol), dopamine receptor antagonists (metoclopramide, domperidone, alizapride) and another prokinetic substance (cisapride) which may be useful for a number of applications as gastro-oesophageal reflux, gastro-paresis, intestinal pseudo-obstruction, cystic fibrosis and constipation, morphine derivatives (e.g. loperamide) for intractable diarrhoea and calcium antagonists (e.g. nifedipine) for achalasia. Increasing experience in digestive tract pharmacology and reliable clinical studies will furthermore be the basis for a more specific and better tolerated therapy of gastrointestinal motility disorders in adults and children.

  3. Intrinsic Photosensitivity Enhances Motility of T Lymphocytes

    PubMed Central

    Phan, Thieu X.; Jaruga, Barbara; Pingle, Sandeep C.; Bandyopadhyay, Bidhan C.; Ahern, Gerard P.

    2016-01-01

    Sunlight has important biological effects in human skin. Ultraviolet (UV) light striking the epidermis catalyzes the synthesis of Vitamin D and triggers melanin production. Although a causative element in skin cancers, sunlight is also associated with positive health outcomes including reduced incidences of autoimmune diseases and cancers. The mechanisms, however, by which light affects immune function remain unclear. Here we describe direct photon sensing in human and mouse T lymphocytes, a cell-type highly abundant in skin. Blue light irradiation at low doses (<300 mJ cm−2) triggers synthesis of hydrogen peroxide (H2O2) in T cells revealed by the genetically encoded reporter HyPerRed. In turn, H2O2 activates a Src kinase/phospholipase C-γ1 (PLC-γ1) signaling pathway and Ca2+ mobilization. Pharmacologic inhibition or genetic disruption of Lck kinase, PLC-γ1 or the T cell receptor complex inhibits light-evoked Ca2+ transients. Notably, both light and H2O2 enhance T-cell motility in a Lck-dependent manner. Thus, T lymphocytes possess intrinsic photosensitivity and this property may enhance their motility in skin. PMID:27995987

  4. Major regulatory mechanisms involved in sperm motility.

    PubMed

    Pereira, Rute; Sá, Rosália; Barros, Alberto; Sousa, Mário

    2017-01-01

    The genetic bases and molecular mechanisms involved in the assembly and function of the flagellum components as well as in the regulation of the flagellar movement are not fully understood, especially in humans. There are several causes for sperm immotility, of which some can be avoided and corrected, whereas other are related to genetic defects and deserve full investigation to give a diagnosis to patients. This review was performed after an extensive literature search on the online databases PubMed, ScienceDirect, and Web of Science. Here, we review the involvement of regulatory pathways responsible for sperm motility, indicating possible causes for sperm immotility. These included the calcium pathway, the cAMP-dependent protein kinase pathway, the importance of kinases and phosphatases, the function of reactive oxygen species, and how the regulation of cell volume and osmolarity are also fundamental components. We then discuss main gene defects associated with specific morphological abnormalities. Finally, we slightly discuss some preventive and treatments approaches to avoid development of conditions that are associated with unspecified sperm immotility. We believe that in the near future, with the development of more powerful techniques, the genetic causes of sperm immotility and the regulatory mechanisms of sperm motility will be better understand, thus enabling to perform a full diagnosis and uncover new therapies.

  5. Major regulatory mechanisms involved in sperm motility

    PubMed Central

    Pereira, Rute; Sá, Rosália; Barros, Alberto; Sousa, Mário

    2017-01-01

    The genetic bases and molecular mechanisms involved in the assembly and function of the flagellum components as well as in the regulation of the flagellar movement are not fully understood, especially in humans. There are several causes for sperm immotility, of which some can be avoided and corrected, whereas other are related to genetic defects and deserve full investigation to give a diagnosis to patients. This review was performed after an extensive literature search on the online databases PubMed, ScienceDirect, and Web of Science. Here, we review the involvement of regulatory pathways responsible for sperm motility, indicating possible causes for sperm immotility. These included the calcium pathway, the cAMP-dependent protein kinase pathway, the importance of kinases and phosphatases, the function of reactive oxygen species, and how the regulation of cell volume and osmolarity are also fundamental components. We then discuss main gene defects associated with specific morphological abnormalities. Finally, we slightly discuss some preventive and treatments approaches to avoid development of conditions that are associated with unspecified sperm immotility. We believe that in the near future, with the development of more powerful techniques, the genetic causes of sperm immotility and the regulatory mechanisms of sperm motility will be better understand, thus enabling to perform a full diagnosis and uncover new therapies. PMID:26680031

  6. Swimming Motility in a Longitudinal Collection of Clinical Isolates of Burkholderia cepacia Complex Bacteria from People with Cystic Fibrosis

    PubMed Central

    Zlosnik, James E. A.; Mori, Paul Y.; To, Derek; Leung, James; Hird, Trevor J.; Speert, David P.

    2014-01-01

    Chronic bacterial lung infections in cystic fibrosis (CF) are the leading cause of morbidity and mortality. While a range of bacteria are known to be capable of establishing residence in the CF lung, only a small number have a clearly established link to deteriorating clinical status. The two bacteria with the clearest roles in CF lung disease are Pseudomonas aeruginosa and bacteria belonging to the Burkholderia cepacia complex (BCC). A number of common adaptations by P. aeruginosa strains to chronic lung infection in CF have been well described. Typically, initial isolates of P. aeruginosa are nonmucoid and display a range of putative virulence determinants. Upon establishment of chronic infection, subsequent isolates ultimately show a reduction in putative virulence determinants, including swimming motility, along with an acquisition of the mucoid phenotype and increased levels of antimicrobial resistance. Infections by BCC are marked by an unpredictable, but typically worse, clinical outcome. However, in contrast to P. aeruginosa infections in CF, studies describing adaptive changes in BCC bacterial phenotype during chronic lung infections are far more limited. To further enhance our understanding of chronic lung infections by BCC bacteria in CF, we assessed the swimming motility phenotype in 551 isolates of BCC bacteria from cystic fibrosis (CF) lung infections between 1981 and 2007. These data suggest that swimming motility is not typically lost by BCC during chronic infection, unlike as seen in P. aeruginosa infections. Furthermore, while we observed a statistically significant link between mucoidy and motility, we did not detect any link between motility phenotype and clinical outcome. These studies highlight the need for further work to understand the adaptive changes of BCC bacteria during chronic infection in the CF lung. PMID:25203161

  7. Elucidation of the Photorhabdus temperata Genome and Generation of a Transposon Mutant Library To Identify Motility Mutants Altered in Pathogenesis

    PubMed Central

    Hurst, Sheldon; Rowedder, Holli; Michaels, Brandye; Bullock, Hannah; Jackobeck, Ryan; Abebe-Akele, Feseha; Durakovic, Umjia; Gately, Jon; Janicki, Erik

    2015-01-01

    ABSTRACT The entomopathogenic nematode Heterorhabditis bacteriophora forms a specific mutualistic association with its bacterial partner Photorhabdus temperata. The microbial symbiont is required for nematode growth and development, and symbiont recognition is strain specific. The aim of this study was to sequence the genome of P. temperata and identify genes that plays a role in the pathogenesis of the Photorhabdus-Heterorhabditis symbiosis. A draft genome sequence of P. temperata strain NC19 was generated. The 5.2-Mb genome was organized into 17 scaffolds and contained 4,808 coding sequences (CDS). A genetic approach was also pursued to identify mutants with altered motility. A bank of 10,000 P. temperata transposon mutants was generated and screened for altered motility patterns. Five classes of motility mutants were identified: (i) nonmotile mutants, (ii) mutants with defective or aberrant swimming motility, (iii) mutant swimmers that do not require NaCl or KCl, (iv) hyperswimmer mutants that swim at an accelerated rate, and (v) hyperswarmer mutants that are able to swarm on the surface of 1.25% agar. The transposon insertion sites for these mutants were identified and used to investigate other physiological properties, including insect pathogenesis. The motility-defective mutant P13-7 had an insertion in the RNase II gene and showed reduced virulence and production of extracellular factors. Genetic complementation of this mutant restored wild-type activity. These results demonstrate a role for RNA turnover in insect pathogenesis and other physiological functions. IMPORTANCE The relationship between Photorhabdus and entomopathogenic nematode Heterorhabditis represents a well-known mutualistic system that has potential as a biological control agent. The elucidation of the genome of the bacterial partner and role that RNase II plays in its life cycle has provided a greater understanding of Photorhabdus as both an insect pathogen and a nematode symbiont. PMID

  8. Effects of physical factors on the swarming motility of text itPseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Si, Tieyan; Ma, Zidong; Tang, Wai Shing; Yang, Alexander; Tang, Jay

    Many species of bacteria can spread over a semi-solid surface via a particular form of collective motion known as surface swarming. Using Pseudomonas aeruginosa as a model organism, we investigate physical factors that either facilitate or restrict the swarming motility. The semi-solid surface is typically formed by 0.5-1% agar containing essential nutrients for the bacterial growth and proliferation. Most bacterial species, including P. aeruginosa, synthesize bio-surfactants to aid in swarming. We found addition of exogenous surfactants such as triton into the agar matrix enhances the swarming. In contrast, increasing agar percentage, infusing osmolites, and adding viscous agents all decrease swarming. We propose that the swarming speed is restricted by the rate of water supply from within the agar gel and by the line tension at the swarm front involving three materials in contact: the air, the bacteria propelled liquid film, and the agar substrate.

  9. Mechanics of swimming of multi-body bacterial swarmers using non-labeled cell tracking algorithm

    NASA Astrophysics Data System (ADS)

    Phuyal, Kiran; Kim, Min Jun

    2013-01-01

    To better understand the survival strategy of bacterial swarmers and the mechanical advantages offered by the linear chain (head-tail) attachment of the multiple bacterial bodies in an individual swarmer cell at low Reynolds number, a non-labeled cell tracking algorithm was used to quantify the mechanics of multi-body flagellated bacteria, Serratia marcescens, swimming in a motility buffer that originally exhibited the swarming motility. Swarming is a type of bacterial motility that is characterized by the collective coordinated motion of differentiated swarmer cells on a two-dimensional surface such as agar. In this study, the bacterial swarmers with multiple cell bodies (2, 3, and 4) were extracted from the swarm plate, and then tracked individually after resuspending in the motility medium. Their motion was investigated and compared with individual undifferentiated swimming bacterial cells. The swarmers when released into the motility buffer swam actively without tumbles. Their speeds, orientations, and the diffusive properties were studied by tracking the individual cell trajectories over a short distance in two-dimensional field when the cells are swimming at a constant depth in a bulk aqueous environment. At short time scales, the ballistic trajectory was dominant for both multi-body swarmers and undifferentiated cells.

  10. Balancing Thymocyte Adhesion and Motility: A Functional Linkage Between β1 Lntegrins and The Motility Receptor RHAMM

    PubMed Central

    Gares, Sheryl L.

    2000-01-01

    Thymocyte differentiation involves several processes that occur in different anatomic sites within the thymus. Therefore, thymocytes must have the ability to respond to signals received from stromal cells and adopt either adhesive or motile behavior. We will discuss our data indicating human thymocytes use α4β1 integrin, α5β1 integrin and RHAMM to mediate these activities. Immature multinegative (MN; CD3–4–8–19-) thymocytes use α4β1 and α5β1 integrins to mediate weak and strong adhesion. This subset also uses α4β1 integrin to mediate motility. As thymocytes differentiate, they begin to express and use RHAMM to mediate motility in conjunction with α4β1 and α5β1 integrins. Motile thymocytes use β1 integrins to maintain weakly adhesive contacts with substrate to provide traction for locomoting cells, thus weak adhesion is a requirement of motile behavior. Hyaluronan (HA) is also required by thymocytes to mediate motility. HA binding to cell surface RHAMM redistributes intracellular RHAMM to the cell surface where it functions to mediate motility. We propose that the decision to maintain adhesive or motile behavior is based on the balance between low and high avidity binding conformations of β1 integrins on thymocytes and that RHAMM:HA interactions decrease high avidity binding conformations of integrins pushing the balance toward motile behavior. PMID:11097213

  11. PqsR-dependent and PqsR-independent regulation of motility and biofilm formation by PQS in Pseudomonas aeruginosa PAO1.

    PubMed

    Guo, Qiao; Kong, Weina; Jin, Sheng; Chen, Lin; Xu, Yangyang; Duan, Kangmin

    2014-07-01

    Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors including swarming motility and biofilm formation. Swarming motility plays an important role in the bacterium's spread to new environments, attachment to surfaces, and biofilm formation. Bacterial biofilm is associated with many persistent infections and increased resistance to antibiotics. In this study, we tested the effect of a 2-alkyl-4(1H)-quinolone (AHQ) signal, the Pseudomonas quinolone signal (PQS) on P. aeruginosa swarming and biofilm formation. Our results show that PQS repressed the swarming motility of P. aeruginosa PAO1. Such repression was independent of its cognate receptor PqsR and was not related to changes in the flagellae, type IV pili or the production of the surface-wetting agent rhamnolipid surfactant. While PQS did not affect twitching motility in PAO1, a pqsR deletion abolished twitching motility, indicating that pqsR is required for twitching motility. Our results also indicate that the enhancement of biofilm formation by PQS is at least partially dependent on the GacAS-Rsm regulatory pathway but does not involve the las or rhl QS systems.

  12. Multiple roles of Pseudomonas aeruginosa TBCF10839 PilY1 in motility, transport and infection

    PubMed Central

    Bohn, Yu-Sing Tammy; Brandes, Gudrun; Rakhimova, Elza; Horatzek, Sonja; Salunkhe, Prabhakar; Munder, Antje; van Barneveld, Andrea; Jordan, Doris; Bredenbruch, Florian; Häußler, Susanne; Riedel, Kathrin; Eberl, Leo; Jensen, Peter Østrup; Bjarnsholt, Thomas; Moser, Claus; Hoiby, Niels; Tümmler, Burkhard; Wiehlmann, Lutz

    2008-01-01

    Polymorphonuclear neutrophils are the most important mammalian host defence cells against infections with Pseudomonas aeruginosa. Screening of a signature tagged mutagenesis library of the non-piliated P. aeruginosa strain TBCF10839 uncovered that transposon inactivation of its pilY1 gene rendered the bacterium more resistant against killing by neutrophils than the wild type and any other of the more than 3000 tested mutants. Inactivation of pilY1 led to the loss of twitching motility in twitching-proficient wild-type PA14 and PAO1 strains, predisposed to autolysis and impaired the secretion of quinolones and pyocyanin, but on the other hand promoted growth in stationary phase and bacterial survival in murine airway infection models. The PilY1 population consisted of a major full-length and a minor shorter PilY1* isoform. PilY1* was detectable in small extracellular quinolone-positive aggregates, but not in the pilus. P. aeruginosa PilY1 is not an adhesin on the pilus tip, but assists in pilus biogenesis, twitching motility, secretion of secondary metabolites and in the control of cell density in the bacterial population. PMID:19054330

  13. Light regulates motility, attachment and virulence in the plant pathogen Pseudomonas syringae pv tomato DC3000.

    PubMed

    Río-Álvarez, Isabel; Rodríguez-Herva, José Juan; Martínez, Pedro Manuel; González-Melendi, Pablo; García-Casado, Gloria; Rodríguez-Palenzuela, Pablo; López-Solanilla, Emilia

    2014-07-01

    Pseudomonas syringae pv tomato DC3000 (Pto) is the causal agent of the bacterial speck of tomato, which leads to significant economic losses in this crop. Pto inhabits the tomato phyllosphere, where the pathogen is highly exposed to light, among other environmental factors. Light represents a stressful condition and acts as a source of information associated with different plant defence levels. Here, we analysed the presence of both blue and red light photoreceptors in a group of Pseudomonas. In addition, we studied the effect of white, blue and red light on Pto features related to epiphytic fitness. While white and blue light inhibit motility, bacterial attachment to plant leaves is promoted. Moreover, these phenotypes are altered in a blue-light receptor mutant. These light-controlled changes during the epiphytic stage cause a reduction in virulence, highlighting the relevance of motility during the entry process to the plant apoplast. This study demonstrated the key role of light perception in the Pto phenotype switching and its effect on virulence.

  14. Pentavalent single-domain antibodies reduce Campylobacter jejuni motility and colonization in chickens.

    PubMed

    Riazi, Ali; Strong, Philippa C R; Coleman, Russell; Chen, Wangxue; Hirama, Tomoko; van Faassen, Henk; Henry, Matthew; Logan, Susan M; Szymanski, Christine M; Mackenzie, Roger; Ghahroudi, Mehdi Arbabi

    2013-01-01

    Campylobacter jejuni is the leading cause of bacterial foodborne illness in the world, with symptoms ranging from acute diarrhea to severe neurological disorders. Contaminated poultry meat is a major source of C. jejuni infection, and therefore, strategies to reduce this organism in poultry, are expected to reduce the incidence of Campylobacter-associated diseases. We have investigated whether oral administration of C. jejuni-specific single-domain antibodies would reduce bacterial colonization levels in chickens. Llama single-domain antibodies specific for C. jejuni were isolated from a phage display library generated from the heavy chain IgG variable domain repertoire of a llama immunized with C. jejuni flagella. Two flagella-specific single-domain antibodies were pentamerized to yield high avidity antibodies capable of multivalent binding to the target antigen. When administered orally to C. jejuni-infected two-day old chicks, the pentabodies significantly reduced C. jejuni colonization in the ceca. In vitro, the motility of the bacteria was also reduced in the presence of the flagella-specific pentabodies, suggesting the mechanism of action is through either direct interference with flagellar motility or antibody-mediated aggregation. Fluorescent microscopy and Western blot analyses revealed specific binding of the anti-flagella pentabodies to the C. jejuni flagellin.

  15. Pentavalent Single-Domain Antibodies Reduce Campylobacter jejuni Motility and Colonization in Chickens

    PubMed Central

    Riazi, Ali; Strong, Philippa C. R.; Coleman, Russell; Chen, Wangxue; Hirama, Tomoko; van Faassen, Henk; Henry, Matthew; Logan, Susan M.; Szymanski, Christine M.; MacKenzie, Roger; Ghahroudi, Mehdi Arbabi

    2013-01-01

    Campylobacter jejuni is the leading cause of bacterial foodborne illness in the world, with symptoms ranging from acute diarrhea to severe neurological disorders. Contaminated poultry meat is a major source of C. jejuni infection, and therefore, strategies to reduce this organism in poultry, are expected to reduce the incidence of Campylobacter-associated diseases. We have investigated whether oral administration of C. jejuni-specific single-domain antibodies would reduce bacterial colonization levels in chickens. Llama single-domain antibodies specific for C. jejuni were isolated from a phage display library generated from the heavy chain IgG variable domain repertoire of a llama immunized with C. jejuni flagella. Two flagella-specific single-domain antibodies were pentamerized to yield high avidity antibodies capable of multivalent binding to the target antigen. When administered orally to C. jejuni-infected two-day old chicks, the pentabodies significantly reduced C. jejuni colonization in the ceca. In vitro, the motility of the bacteria was also reduced in the presence of the flagella-specific pentabodies, suggesting the mechanism of action is through either direct interference with flagellar motility or antibody-mediated aggregation. Fluorescent microscopy and Western blot analyses revealed specific binding of the anti-flagella pentabodies to the C. jejuni flagellin. PMID:24391847

  16. The Aeromonas caviae AHA0618 gene modulates cell length and influences swimming and swarming motility.

    PubMed

    Lowry, Rebecca C; Parker, Jennifer L; Kumbhar, Ramhari; Mesnage, Stephane; Shaw, Jonathan G; Stafford, Graham P

    2014-12-17

    Aeromonas caviae is motile via a polar flagellum in liquid culture, with a lateral flagella system used for swarming on solid surfaces. The polar flagellum also has a role in cellular adherence and biofilm formation. The two subunits of the polar flagellum, FlaA and FlaB, are posttranslationally modified by O-linked glycosylation with pseudaminic acid on 6-8 serine and threonine residues within the central region of these proteins. This modification is essential for the formation of the flagellum. Aeromonas caviae possesses the simplest set of genes required for bacterial glycosylation currently known, with the putative glycosyltransferase, Maf1, being described recently. Here, we investigated the role of the AHA0618 gene, which shares homology (37% at the amino acid level) with the central region of a putative deglycosylation enzyme (HP0518) from the human pathogen Helicobacter pylori, which also glycosylates its flagellin and is proposed to be part of a flagellin deglycosylation pathway. Phenotypic analysis of an AHA0618 A. caviae mutant revealed increased swimming and swarming motility compared to the wild-type strain but without any detectable effects on the glycosylation status of the polar flagellins when analyzed by western blot analysis or mass spectroscopy. Bioinformatic analysis of the protein AHA0618, demonstrated homology to a family of l,d-transpeptidases involved in cell wall biology and peptidoglycan cross-linking (YkuD-like). Scanning electron microscopy (SEM) and fluorescence microscopy analysis of the wild-type and AHA0618-mutant A. caviae strains revealed the mutant to be subtly but significantly shorter than wild-type cells; a phenomenon that could be recovered when either AHA0618 or H. pylori HP0518 were introduced. We can therefore conclude that AHA0618 does not affect A. caviae behavior by altering polar flagellin glycosylation levels but is likely to have a role in peptidoglycan processing at the bacterial cell wall, consequently altering

  17. Motility and chemotaxis mediate the preferential colonization of gastric injury sites by Helicobacter pylori.

    PubMed

    Aihara, Eitaro; Closson, Chet; Matthis, Andrea L; Schumacher, Michael A; Engevik, Amy C; Zavros, Yana; Ottemann, Karen M; Montrose, Marshall H

    2014-07-01

    Helicobacter pylori (H. pylori) is a pathogen contributing to peptic inflammation, ulceration, and cancer. A crucial step in the pathogenic sequence is when the bacterium first interacts with gastric tissue, an event that is poorly understood in vivo. We have shown that the luminal space adjacent to gastric epithelial damage is a microenvironment, and we hypothesized that this microenvironment might enhance H. pylori colonization. Inoculation with 106 H. pylori (wild-type Sydney Strain 1, SS1) significantly delayed healing of acetic-acid induced ulcers at Day 1, 7 and 30 post-inoculation, and wild-type SS1 preferentially colonized the ulcerated area compared to uninjured gastric tissue in the same animal at all time points. Gastric resident Lactobacillus spp. did not preferentially colonize ulcerated tissue. To determine whether bacterial motility and chemotaxis are important to ulcer healing and colonization, we analyzed isogenic H. pylori mutants defective in motility (ΔmotB) or chemotaxis (ΔcheY). ΔmotB (10(6)) failed to colonize ulcerated or healthy stomach tissue. ΔcheY (10(6)) colonized both tissues, but without preferential colonization of ulcerated tissue. However, ΔcheY did modestly delay ulcer healing, suggesting that chemotaxis is not required for this process. We used two-photon microscopy to induce microscopic epithelial lesions in vivo, and evaluated accumulation of fluorescently labeled H. pylori at gastric damage sites in the time frame of minutes instead of days. By 5 min after inducing damage, H. pylori SS1 preferentially accumulated at the site of damage and inhibited gastric epithelial restitution. H. pylori ΔcheY modestly accumulated at the gastric surface and inhibited restitution, but did not preferentially accumulate at the injury site. H. pylori ΔmotB neither accumulated at the surface nor inhibited restitution. We conclude that bacterial chemosensing and motility rapidly promote H. pylori colonization of injury sites, and thereby

  18. Bacterial Transport Experiments in Fractured Crystalline Bedrock

    USGS Publications Warehouse

    Becker, M.W.; Metge, D.W.; Collins, S.A.; Shapiro, A.M.; Harvey, R.W.

    2003-01-01

    The efficiency of contaminant biodegradation in ground water depends, in part, on the transport properties of the degrading bacteria. Few data exist concerning the transport of bacteria in saturated bedrock, particularly at the field scale. Bacteria and microsphere tracer experiments were conducted in a fractured crystalline bedrock under forced-gradient conditions over a distance of 36 m. Bacteria isolated from the local ground water were chosen on the basis of physicochemical and physiological differences (shape, cell-wall type, motility), and were differentially stained so that their transport behavior could be compared. No two bacterial strains transported in an identical manner, and microspheres produced distinctly different breakthrough curves than bacteria. Although there was insufficient control in this field experiment to completely separate the effects of bacteria shape, reaction to Gram staining, cell size, and motility on transport efficiency, it was observed that (1) the nonmotile, mutant strain exhibited better fractional recovery than the motile parent strain; (2) Gram-negative rod-shaped bacteria exhibited higher fractional recovery relative to the Gram-positive rod-shaped strain of similar size; and (3) coccoidal (spherical-shaped) bacteria transported better than all but one strain of the rod-shaped bacteria. The field experiment must be interpreted in the context of the specific bacterial strains and ground water environment in which they were conducted, but experimental results suggest that minor differences in the physical properties of bacteria can lead to major differences in transport behavior at the field scale.

  19. Quantum-dot-based cell motility assay.

    PubMed

    Gu, Weiwei; Pellegrino, Teresa; Parak, Wolfgang J; Boudreau, Rosanne; Le Gros, Mark A; Gerion, Daniele; Alivisatos, A Paul; Larabell, Carolyn A

    2005-06-28

    Because of their favorable physical and photochemical properties, colloidal CdSe/ZnS-semiconductor nanocrystals (commonly known as quantum dots) have enormous potential for use in biological imaging. In this report, we present an assay that uses quantum dots as markers to quantify cell motility. Cells that are seeded onto a homogeneous layer of quantum dots engulf and absorb the nanocrystals and, as a consequence, leave behind a fluorescence-free trail. By subsequently determining the ratio of cell area to fluorescence-free track area, we show that it is possible to differentiate between invasive and noninvasive cancer cells. Because this assay uses simple fluorescence detection, requires no significant data processing, and can be used in live-cell studies, it has the potential to be a powerful new tool for discriminating between invasive and noninvasive cancer cell lines or for studying cell signaling events involved in migration.

  20. Spontaneous Motility of Actin Lamellar Fragments

    NASA Astrophysics Data System (ADS)

    Blanch-Mercader, C.; Casademunt, J.

    2013-02-01

    We show that actin lamellar fragments driven solely by polymerization forces at the bounding membrane are generically motile when the circular symmetry is spontaneously broken, with no need of molecular motors or global polarization. We base our study on a nonlinear analysis of a recently introduced minimal model [Callan-Jones et al., Phys. Rev. Lett. 100, 258106 (2008)PRLTAO0031-900710.1103/PhysRevLett.100.258106]. We prove the nonlinear instability of the center of mass and find an exact and simple relation between shape and center-of-mass velocity. A complex subcritical bifurcation scenario into traveling solutions is unfolded, where finite velocities appear through a nonadiabatic mechanism. Examples of traveling solutions and their stability are studied numerically.

  1. Mechanics model for actin-based motility

    NASA Astrophysics Data System (ADS)

    Lin, Yuan

    2009-02-01

    We present here a mechanics model for the force generation by actin polymerization. The possible adhesions between the actin filaments and the load surface, as well as the nucleation and capping of filament tips, are included in this model on top of the well-known elastic Brownian ratchet formulation. A closed form solution is provided from which the force-velocity relationship, summarizing the mechanics of polymerization, can be drawn. Model predictions on the velocity of moving beads driven by actin polymerization are consistent with experiment observations. This model also seems capable of explaining the enhanced actin-based motility of Listeria monocytogenes and beads by the presence of Vasodilator-stimulated phosphoprotein, as observed in recent experiments.

  2. Mechanics model for actin-based motility.

    PubMed

    Lin, Yuan

    2009-02-01

    We present here a mechanics model for the force generation by actin polymerization. The possible adhesions between the actin filaments and the load surface, as well as the nucleation and capping of filament tips, are included in this model on top of the well-known elastic Brownian ratchet formulation. A closed form solution is provided from which the force-velocity relationship, summarizing the mechanics of polymerization, can be drawn. Model predictions on the velocity of moving beads driven by actin polymerization are consistent with experiment observations. This model also seems capable of explaining the enhanced actin-based motility of Listeria monocytogenes and beads by the presence of Vasodilator-stimulated phosphoprotein, as observed in recent experiments.

  3. Method and system for enhancing microbial motility

    SciTech Connect

    Hazen, T.C.; Lopez-De-Victoria, G.

    1992-12-31

    A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant.

  4. Method and system for enhancing microbial motility

    SciTech Connect

    Hazen, T.C.; Lopez-De-Victoria, G.

    1990-01-05

    A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant. 5 figs.

  5. Motility recovery during the process of regeneration in freshwater planarians.

    PubMed

    Kato, Chihiro; Mihashi, Koshin; Ishida, Sachiko

    2004-04-02

    Planarians are phylogenetically considered to be the most primitive animals to have acquired a central nervous system and a bilateral symmetry. However, very little is known about the relationship between planarian brain integration and motility. A behavioural and histological study was therefore undertaken in an aspect of planarian motility recovery during its process of regeneration. Quantitative analysis showed that the tail-regenerates recovered their motility gradually as the new heads reformed, while the non-head reforming tail fragments showed no signs of recovery. The head fragments recovered their motility soon after cutting. The cephalic margin was not a function of the motility. The brain regenerated back to its original form in approximately two weeks, the same amount of time it took for the decapitated tails to recover their motility to initial levels. This study provides quantitative evidence that the planarian motility recovered in relation to the head formation during its process of regeneration. Our results reinforce the view that the brain plays a functional part in activating planarian motility.

  6. Quantification of motility of carabid beetles in farmland.

    PubMed

    Allema, A B; van der Werf, W; Groot, J C J; Hemerik, L; Gort, G; Rossing, W A H; van Lenteren, J C

    2015-04-01

    Quantification of the movement of insects at field and landscape levels helps us to understand their ecology and ecological functions. We conducted a meta-analysis on movement of carabid beetles (Coleoptera: Carabidae), to identify key factors affecting movement and population redistribution. We characterize the rate of redistribution using motility μ (L2 T-1), which is a measure for diffusion of a population in space and time that is consistent with ecological diffusion theory and which can be used for upscaling short-term data to longer time frames. Formulas are provided to calculate motility from literature data on movement distances. A field experiment was conducted to measure the redistribution of mass-released carabid, Pterostichus melanarius in a crop field, and derive motility by fitting a Fokker-Planck diffusion model using inverse modelling. Bias in estimates of motility from literature data is elucidated using the data from the field experiment as a case study. The meta-analysis showed that motility is 5.6 times as high in farmland as in woody habitat. Species associated with forested habitats had greater motility than species associated with open field habitats, both in arable land and woody habitat. The meta-analysis did not identify consistent differences in motility at the species level, or between clusters of larger and smaller beetles. The results presented here provide a basis for calculating time-varying distribution patterns of carabids in farmland and woody habitat. The formulas for calculating motility can be used for other taxa.

  7. Laser radiation and motility patterns of human sperm

    SciTech Connect

    Lenzi, A.; Claroni, F.; Gandini, L.; Lombardo, F.; Barbieri, C.; Lino, A.; Dondero, F. )

    1989-01-01

    Human sperm were exposed in vitro to laser radiation. An increase in progressive sperm motility was associated with a faster rate of sperm ATP consumption. Computer-assisted analysis of sperm motility confirmed the positive effect of laser irradiation on velocity and linearity of sperm.

  8. Detection and Genomic Characterization of Motility in Lactobacillus curvatus: Confirmation of Motility in a Species outside the Lactobacillus salivarius Clade

    PubMed Central

    Cousin, Fabien J.; Lynch, Shónagh M.; Harris, Hugh M. B.; McCann, Angela; Lynch, Denise B.; Neville, B. Anne; Irisawa, Tomohiro; Okada, Sanae; Endo, Akihito

    2014-01-01

    Lactobacillus is the largest genus within the lactic acid bacteria (LAB), with almost 180 species currently identified. Motility has been reported for at least 13 Lactobacillus species, all belonging to the Lactobacillus salivarius clade. Motility in lactobacilli is poorly characterized. It probably confers competitive advantages, such as superior nutrient acquisition and niche colonization, but it could also play an important role in innate immune system activation through flagellin–Toll-like receptor 5 (TLR5) interaction. We now report strong evidence of motility in a species outside the L. salivarius clade, Lactobacillus curvatus (strain NRIC 0822). The motility of L. curvatus NRIC 0822 was revealed by phase-contrast microscopy and soft-agar motility assays. Strain NRIC 0822 was motile at temperatures between 15°C and 37°C, with a range of different carbohydrates, and under varying atmospheric conditions. We sequenced the L. curvatus NRIC 0822 genome, which revealed that the motility genes are organized in a single operon and that the products are very similar (>98.5% amino acid similarity over >11,000 amino acids) to those encoded by the motility operon of Lactobacillus acidipiscis KCTC 13900 (shown for the first time to be motile also). Moreover, the presence of a large number of mobile genetic elements within and flanking the motility operon of L. curvatus suggests recent horizontal transfer between members of two distinct Lactobacillus clades: L. acidipiscis in the L. salivarius clade and L. curvatus in the L. sakei clade. This study provides novel phenotypic, genetic, and phylogenetic insights into flagellum-mediated motility in lactobacilli. PMID:25501479

  9. Detection and genomic characterization of motility in Lactobacillus curvatus: confirmation of motility in a species outside the Lactobacillus salivarius clade.

    PubMed

    Cousin, Fabien J; Lynch, Shónagh M; Harris, Hugh M B; McCann, Angela; Lynch, Denise B; Neville, B Anne; Irisawa, Tomohiro; Okada, Sanae; Endo, Akihito; O'Toole, Paul W

    2015-02-01

    Lactobacillus is the largest genus within the lactic acid bacteria (LAB), with almost 180 species currently identified. Motility has been reported for at least 13 Lactobacillus species, all belonging to the Lactobacillus salivarius clade. Motility in lactobacilli is poorly characterized. It probably confers competitive advantages, such as superior nutrient acquisition and niche colonization, but it could also play an important role in innate immune system activation through flagellin–Toll-like receptor 5 (TLR5) interaction. We now report strong evidence of motility in a species outside the L. salivarius clade, Lactobacillus curvatus (strain NRIC0822). The motility of L. curvatus NRIC 0822 was revealed by phase-contrast microscopy and soft-agar motility assays. Strain NRIC 0822 was motile at temperatures between 15 °C and 37 °C, with a range of different carbohydrates, and under varying atmospheric conditions. We sequenced the L. curvatus NRIC 0822 genome, which revealed that the motility genes are organized in a single operon and that the products are very similar (>98.5% amino acid similarity over >11,000 amino acids) to those encoded by the motility operon of Lactobacillus acidipiscis KCTC 13900 (shown for the first time to be motile also). Moreover, the presence of a large number of mobile genetic elements within and flanking the motility operon of L. curvatus suggests recent horizontal transfer between members of two distinct Lactobacillus clades: L. acidipiscis in the L. salivarius clade and L. curvatus inthe L. sakei clade. This study provides novel phenotypic, genetic, and phylogenetic insights into flagellum-mediated motility in lactobacilli.

  10. Kinematic analysis of Toxoplasma gondii motility.

    PubMed

    Frixione, E; Mondragón, R; Meza, I

    1996-01-01

    Toxoplasma gondii tachyzoites execute a complex and little understood combination of rapid movements to reach and penetrate human or other animals cells. In the present study, computer-assisted simulation was used to quantitatively analyze the motility of these parasites in three-dimensional space with spatial and temporal resolutions in the micrometer and subsecond ranges. A digital model based on electron-micrographs of a serially sectioned tachyzoite was animated according to a videomicrographed sequence of a characteristic repetitive movement. Keyframe animation defined over 150 frames by a total of 36 kinematic parameters for specific motions, of both the whole model and particular domains, resulted in a real-time life-like simulation of the videorecorded tachyzoite movement. The kinematic values indicate that a full revolution of the model is composed of three half-turns accomplished in nearly 5 s with two phases: a relatively slow 180 degrees tilting with regard to the substratum plane, followed by fast (over 200 degrees/s) spinning almost simultaneous with pivoting around the posterior end, each clockwise and for about 180 degrees. Maximal flexing of the body, as well as bowing and retraction of its anterior end, occur at midway during the tilting phase. An estimated 70 degrees. clockwise torsion of the body seems to precede the spinning-pivoting phase. The results suggest the operation of two basic forces in the motility of T. gondii tachyzoites: (1) a clockwise torque that causes torsion, spinning, and pivoting; and (2) a longitudinal pull that contracts, bends and tilts the parasite. We discuss the possibility that both of these forces might result from the action of an actin-myosin system enveloping the twisted framework of microtubules characteristic of these organisms.

  11. Thyroxin Is Useful to Improve Sperm Motility

    PubMed Central

    Mendeluk, Gabriela Ruth; Rosales, Mónica

    2016-01-01

    Background The aim of this study was to evaluate the non-genomic action of thyroxin on sperm kinetic and its probable use to improve sperm recovery after applying an en- richment method like “swim-up” in comparison with the available one, pentoxifylline. Materials and Methods This is an experimental study. A total of 50 patients were re- cruited, followed by infertility consultation. Conventional sperm assays were performed according to World Health Organization criteria-2010 (WHO-2010). A Computer Aided Semen Analysis System was employed to assess kinetic parameters and concentrations. Number of the motile sperm recovered after preparation technique was calculated. Results Addition of T4 (0.002 µg/ml) to semen samples increased hypermotility at 20 minutes (control: 14.18 ± 5.1% vs. 17.66 ± 8.88%, P<0.03, data expressed as mean ± SD) and remained unchanged after 40 minutes. Significant differences were found in the motile sperm recovered after swim-up (control: 8.93×106 ± 9.52× 06vs. 17.20×106 ± 21.16×106, P<0.03), achieving all of the tested samples a desirable threshold value for artificial insemination outcome, while adding pentoxifylline increased the number of recovered sperm after swim-up in 60% of the studied cases. No synergism between two treatments could be determined. Conclusion We propose a new physiological tool to artificially improve insemination. The discussion opens windows to investigate unknown pathways involved in sperm ca- pacitation and gives innovative arguments to better understand infertility mechanisms. PMID:27441054

  12. Gliding Motility Revisited: How Do the Myxobacteria Move without Flagella?

    PubMed Central

    Mauriello, Emilia M. F.; Mignot, Tâm; Yang, Zhaomin; Zusman, David R.

    2010-01-01

    Summary: In bacteria, motility is important for a wide variety of biological functions such as virulence, fruiting body formation, and biofilm formation. While most bacteria move by using specialized appendages, usually external or periplasmic flagella, some bacteria use other mechanisms for their movements that are less well characterized. These mechanisms do not always exhibit obvious motility structures. Myxococcus xanthus is a motile bacterium that does not produce flagella but glides slowly over solid surfaces. How M. xanthus moves has remained a puzzle that has challenged microbiologists for over 50 years. Fortunately, recent advances in the analysis of motility mutants, bioinformatics, and protein localization have revealed likely mechanisms for the two M. xanthus motility systems. These results are summarized in this review. PMID:20508248

  13. Analysis of energy sources for Mycoplasma penetrans gliding motility.

    PubMed

    Jurkovic, Dominika A; Hughes, Michael R; Balish, Mitchell F

    2013-01-01

    Mycoplasma penetrans, a potential human pathogen found mainly in HIV-infected individuals, uses a tip structure for both adherence and gliding motility. To improve our understanding of the molecular mechanism of M. penetrans gliding motility, we used chemical inhibitors of energy sources associated with motility of other organisms to determine which of these is used by M. penetrans and also tested whether gliding speed responded to temperature and pH. Mycoplasma penetrans gliding motility was not eliminated in the presence of a proton motive force inhibitor, a sodium motive force inhibitor, or an agent that depletes cellular ATP. At near-neutral pH, gliding speed increased as temperature increased. The absence of a clear chemical energy source for gliding motility and a positive correlation between speed and temperature suggest that energy derived from heat provides the major source of power for the gliding motor of M. penetrans.

  14. Motile axonal mitochondria contribute to the variability of presynaptic strength.

    PubMed

    Sun, Tao; Qiao, Haifa; Pan, Ping-Yue; Chen, Yanmin; Sheng, Zu-Hang

    2013-08-15

    One of the most notable characteristics of synaptic transmission is the wide variation in synaptic strength in response to identical stimulation. In hippocampal neurons, approximately one-third of axonal mitochondria are highly motile, and some dynamically pass through presynaptic boutons. This raises a fundamental question: can motile mitochondria contribute to the pulse-to-pulse variability of presynaptic strength? Recently, we identified syntaphilin as an axonal mitochondrial-docking protein. Using hippocampal neurons and slices of syntaphilin knockout mice, we demonstrate that the motility of axonal mitochondria correlates with presynaptic variability. Enhancing mitochondrial motility increases the pulse-to-pulse variability, whereas immobilizing mitochondria reduces the variability. By dual-color live imaging at single-bouton levels, we further show that motile mitochondria passing through boutons dynamically influence synaptic vesicle release, mainly by altering ATP homeostasis in axons. Thus, our study provides insight into the fundamental properties of the CNS to ensure the plasticity and reliability of synaptic transmission.

  15. Computational approaches to substrate-based cell motility

    NASA Astrophysics Data System (ADS)

    Ziebert, Falko; Aranson, Igor S.

    2016-07-01

    Substrate-based crawling motility of eukaryotic cells is essential for many biological functions, both in developing and mature organisms. Motility dysfunctions are involved in several life-threatening pathologies such as cancer and metastasis. Motile cells are also a natural realisation of active, self-propelled 'particles', a popular research topic in nonequilibrium physics. Finally, from the materials perspective, assemblies of motile cells and evolving tissues constitute a class of adaptive self-healing materials that respond to the topography, elasticity and surface chemistry of the environment and react to external stimuli. Although a comprehensive understanding of substrate-based cell motility remains elusive, progress has been achieved recently in its modelling on the whole-cell level. Here we survey the most recent advances in computational approaches to cell movement and demonstrate how these models improve our understanding of complex self-organised systems such as living cells.

  16. A mechanism for cell motility by active polar gels

    PubMed Central

    Marth, W.; Praetorius, S.; Voigt, A.

    2015-01-01

    We analyse a generic motility model, with the motility mechanism arising by contractile stress due to the interaction of myosin and actin. A hydrodynamic active polar gel theory is used to model the cytoplasm of a cell and is combined with a Helfrich-type model to account for membrane properties. The overall model allows consideration of the motility without the necessity for local adhesion. Besides a detailed numerical approach together with convergence studies for the highly nonlinear free boundary problem, we also compare the induced flow field of the motile cell with that of classical squirmer models and identify the motile cell as a puller or pusher, depending on the strength of the myosin–actin interactions. PMID:25926698

  17. Esophageal motility in nonacid reflux compared with acid reflux.

    PubMed

    Wang, Victor S; Feldman, Natan; Maurer, Rie; Burakoff, Robert

    2009-09-01

    Esophageal motility has been well studied in gastroesophageal reflux disease (GERD) and acid reflux, but not in nonacid reflux. Consecutive patients who had both 24-h multichannel intraluminal impedance-pH (MII-pH) and esophageal motility tests for suspected GERD were studied. Patients were grouped into nonacid refluxers, acid refluxers, and nonrefluxers based on positive symptom correlation and objective findings of acid reflux. Of 96 patients enrolled, 21 patients (22%) were nonacid refluxers, 44 patients (46%) were acid refluxers, and 31 patients (32%) had no objective evidence of reflux. Normal motility was recorded in 86% of nonacid refluxers, 71% of acid refluxers, and 60% of nonrefluxers. Ineffective esophageal motility was seen in 24% of acid refluxers, and 5% of nonacid refluxers (P = 0.11). Symptomatic nonacid reflux events comprised 22% of patients studied for GERD symptoms by MII-pH. Esophageal motility in nonacid reflux is normal 86% of the time.

  18. Light regulation of type IV pilus-dependent motility by chemosensor-like elements in Synechocystis PCC6803

    PubMed Central

    Bhaya, Devaki; Takahashi, Akiko; Grossman, Arthur R.

    2001-01-01

    To optimize photosynthesis, cyanobacteria move toward or away from a light source by a process known as phototaxis. Phototactic movement of the cyanobacterium Synechocystis PCC6803 is a surface-dependent phenomenon that requires type IV pili, cellular appendages implicated in twitching and social motility in a range of bacteria. To elucidate regulation of cyanobacterial motility, we generated transposon-tagged mutants with aberrant phototaxis; mutants were either nonmotile or exhibited an “inverted motility response” (negative phototaxis) relative to wild-type cells. Several mutants contained transposons in genes similar to those involved in bacterial chemotaxis. Synechocystis PCC6803 has three loci with chemotaxis-like genes, of which two, Tax1 and Tax3, are involved in phototaxis. Transposons interrupting the Tax1 locus yielded mutants that exhibited an inverted motility response, suggesting that this locus is involved in controlling positive phototaxis. However, a strain null for taxAY1 was nonmotile and hyperpiliated. Interestingly, whereas the C-terminal region of the TaxD1 polypeptide is similar to the signaling domain of enteric methyl-accepting chemoreceptor proteins, the N terminus has two domains resembling chromophore-binding domains of phytochrome, a photoreceptor in plants. Hence, TaxD1 may play a role in perceiving the light stimulus. Mutants in the Tax3 locus are nonmotile and do not make type IV pili. These findings establish links between chemotaxis-like regulatory elements and type IV pilus-mediated phototaxis. PMID:11404477

  19. Motile and non-motile cilia in human pathology: from function to phenotypes.

    PubMed

    Mitchison, Hannah M; Valente, Enza Maria

    2017-01-01

    Ciliopathies are inherited human disorders caused by both motile and non-motile cilia dysfunction that form an important and rapidly expanding disease category. Ciliopathies are complex conditions to diagnose, being multisystem disorders characterized by extensive genetic heterogeneity and clinical variability with high levels of lethality. There is marked phenotypic overlap among distinct ciliopathy syndromes that presents a major challenge for their recognition, diagnosis, and clinical management, in addition to posing an on-going task to develop the most appropriate family counselling. The impact of next-generation sequencing and high-throughput technologies in the last decade has significantly improved our understanding of the biological basis of ciliopathy disorders, enhancing our ability to determine the possible reasons for the extensive overlap in their symptoms and genetic aetiologies. Here, we review the diverse functions of cilia in human health and disease and discuss a growing shift away from the classical clinical definitions of ciliopathy syndromes to a more functional categorization. This approach arises from our improved understanding of this unique organelle, revealed through new genetic and cell biological insights into the discrete functioning of subcompartments of the cilium (basal body, transition zone, intraflagellar transport, motility). Mutations affecting these distinct ciliary protein modules can confer different genetic diseases and new clinical classifications are possible to define, according to the nature and extent of organ involvement. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  20. Regulators of gut motility revealed by a gnotobiotic model of diet-microbiome interactions related to travel.

    PubMed

    Dey, Neelendu; Wagner, Vitas E; Blanton, Laura V; Cheng, Jiye; Fontana, Luigi; Haque, Rashidul; Ahmed, Tahmeed; Gordon, Jeffrey I

    2015-09-24

    To understand how different diets, the consumers' gut microbiota, and the enteric nervous system (ENS) interact to regulate gut motility, we developed a gnotobiotic mouse model that mimics short-term dietary changes that happen when humans are traveling to places with different culinary traditions. Studying animals transplanted with the microbiota from humans representing diverse culinary traditions and fed a sequence of diets representing those of all donors, we found that correlations between bacterial species abundances and transit times are diet dependent. However, the levels of unconjugated bile acids-generated by bacterial bile salt hydrolases (BSH)-correlated with faster transit, including during consumption of a Bangladeshi diet. Mice harboring a consortium of sequenced cultured bacterial strains from the Bangladeshi donor's microbiota and fed a Bangladeshi diet revealed that the commonly used cholekinetic spice, turmeric, affects gut motility through a mechanism that reflects bacterial BSH activity and Ret signaling in the ENS. These results demonstrate how a single food ingredient interacts with a functional microbiota trait to regulate host physiology.

  1. Emergence of macroscopic directed motion in populations of motile colloids

    NASA Astrophysics Data System (ADS)

    Bricard, Antoine; Caussin, Jean-Baptiste; Desreumaux, Nicolas; Dauchot, Olivier; Bartolo, Denis

    2013-11-01

    From the formation of animal flocks to the emergence of coordinated motion in bacterial swarms, populations of motile organisms at all scales display coherent collective motion. This consistent behaviour strongly contrasts with the difference in communication abilities between the individuals. On the basis of this universal feature, it has been proposed that alignment rules at the individual level could solely account for the emergence of unidirectional motion at the group level. This hypothesis has been supported by agent-based simulations. However, more complex collective behaviours have been systematically found in experiments, including the formation of vortices, fluctuating swarms, clustering and swirling. All these (living and man-made) model systems (bacteria, biofilaments and molecular motors, shaken grains and reactive colloids) predominantly rely on actual collisions to generate collective motion. As a result, the potential local alignment rules are entangled with more complex, and often unknown, interactions. The large-scale behaviour of the populations therefore strongly depends on these uncontrolled microscopic couplings, which are extremely challenging to measure and describe theoretically. Here we report that dilute populations of millions of colloidal rolling particles self-organize to achieve coherent motion in a unique direction, with very few density and velocity fluctuations. Quantitatively identifying the microscopic interactions between the rollers allows a theoretical description of this polar-liquid state. Comparison of the theory with experiment suggests that hydrodynamic interactions promote the emergence of collective motion either in the form of a single macroscopic `flock', at low densities, or in that of a homogenous polar phase, at higher densities. Furthermore, hydrodynamics protects the polar-liquid state from the giant density fluctuations that were hitherto considered the hallmark of populations of self-propelled particles. Our

  2. Electrophysiological principles of motility disturbances in the small and large intestines--review of the literature and personal experience.

    PubMed

    Holschneider, A M

    1989-01-01

    Motility disturbances of the small and large intestines are based on changes in the smooth-muscle potential, whereby the number of amplitudes and configuration of slow waves and of spike potentials as well as pattern, speed of propagation, and duration of the MMC are of crucial importance. Whereas the electromechanical principles of intestinal motility are sufficiently known, changes in the electromechanical activity in clinically manifest motility disturbances have as yet not been given due regard. Only recently, electromechanical measurements in the upper gastrointestinal tract and colon were performed in several gastrointestinal diseases of internal medicine. In the small intestine, changes in slow waves, spike potentials, and the MMC could be disclosed which are typical for hyperthyrosis, hypothyrosis, irritable bowel syndrome, bacterial diarrhea, primary and secondary intestinal pseudo-obstruction, short-bowel syndrome, postoperative bowel atonia, mechanical bowel obstruction, vagotomy, and diabetic enteropathy with disturbed gastric emptying. Regarding the colon, a disturbance in the electromechanical characteristics was found in irritable bowel syndrome, bacterial overgrowth in the small bowel, chronic constipation, and idiopathic intestinal pseudo-obstruction, which is probably identical with the clinical picture of adynamic ileus. Based on a thorough examination of the literature and on own results from electromechanical measurements in children, electromechanical disturbances have been narrowly defined.

  3. Bacterial motion in narrow capillaries

    PubMed Central

    Ping, Liyan; Wasnik, Vaibhav; Emberly, Eldon

    2014-01-01

    Motile bacteria often have to pass through small tortuous pores in soil or tissue of higher organisms. However, their motion in this prevalent type of niche is not fully understood. Here, we modeled it with narrow glass capillaries and identified a critical radius (Rc) for bacterial motion. Near the surface of capillaries narrower than that, the swimming trajectories are helices. In larger capillaries, they swim in distorted circles. Under non-slip condition, the peritrichous Escherichia coli swam in left-handed helices with an Rc of ∼10 μm near glass surface. However, slipping could occur in the fast monotrichous Pseudomonas fluorescens, when a speed threshold was exceeded, and thus both left-handed and right-handed helices were executed in glass capillaries. In the natural non-cylindrical pores, the near-surface trajectories would be spirals and twisted loops. Engaging in such motions reduces the bacterial migration rate. With a given pore size, the run length and the tumbling angle of the bacterium determine the probability and duration of their near-surface motion. Shear flow and chemotaxis potentially enhance it. Based on this observation, the puzzling previous observations on bacterial migration in porous environments can be interpreted. PMID:25764548

  4. Ineffective esophageal motility (IEM): the primary finding in patients with nonspecific esophageal motility disorder.

    PubMed

    Leite, L P; Johnston, B T; Barrett, J; Castell, J A; Castell, D O

    1997-09-01

    Nonspecific esophageal motility disorder (NEMD) is a vague category used to include patients with poorly defined esophageal contraction abnormalities. The criteria include "ineffective" contraction waves, ie, peristaltic waves that are either of low amplitude or are not transmitted. The aim of this study was to identify the prevalence of ineffective esophageal motility (IEM) found during manometry testing and to evaluate esophageal acid exposure and esophageal acid clearance (EAC) in patients with IEM compared to those with other motility findings. We analyzed esophageal manometric tracings from 600 consecutive patients undergoing manometry in our laboratory following a specific protocol from April 1992 through October 1994 to identify the frequency of ineffective contractions and the percentages of other motility abnormalities present in patients meeting criteria for NEMD. Comparison of acid exposure and EAC was made with 150 patients who also had both esophageal manometry and pH-metry over the same time period. Sixty-one of 600 patients (10%) met the diagnostic criteria for NEMD. Sixty of 61 (98%) of these patients had IEM, defined by at least 30% ineffective contractions out of 10 wet swallows. Thirty-five of these patients also underwent ambulatory esophageal pH monitoring. Patients with IEM demonstrated significant increases in both recumbent median percentage of time of pH <4 (4.5%) and median distal EAC (4.2 min/episode) compared to those with normal motility (0.2%, 1 min/episode), diffuse esophageal spasm (0%, 0.6 min/episode), hypertensive LES (0%, 1.8 min/episode), and nutcracker esophagus (0.4% 1.6 min/episode). Recumbent acid exposure in IEM did not differ significantly from that in patients with systemic scleroderma (SSc) for either variable (5.4%, 4.2 min/episode). We propose that IEM is a more appropriate term and should replace NEMD, giving it a more specific manometric identity. IEM patients demonstrate a distinctive recumbent reflux pattern

  5. Type IV pilin is glycosylated in Pseudomonas syringae pv. tabaci 6605 and is required for surface motility and virulence.

    PubMed

    Nguyen, Linh Chi; Taguchi, Fumiko; Tran, Quang Minh; Naito, Kana; Yamamoto, Masanobu; Ohnishi-Kameyama, Mayumi; Ono, Hiroshi; Yoshida, Mitsuru; Chiku, Kazuhiro; Ishii, Tadashi; Inagaki, Yoshishige; Toyoda, Kazuhiro; Shiraishi, Tomonori; Ichinose, Yuki

    2012-09-01

    Type IV pilin (PilA) is a major constituent of pilus and is required for bacterial biofilm formation, surface motility and virulence. It is known that mature PilA is produced by cleavage of the short leader sequence of the pilin precursor, followed by methylation of N-terminal phenylalanine. The molecular mass of the PilA mature protein from the tobacco bacterial pathogen Pseudomonas syringae pv. tabaci 6605 (Pta 6605) has been predicted to be 12 329 Da from its deduced amino acid sequence. Previously, we have detected PilA as an approximately 13-kDa protein by immunoblot analysis with anti-PilA-specific antibody. In addition, we found the putative oligosaccharide-transferase gene tfpO downstream of pilA. These findings suggest that PilA in Pta 6605 is glycosylated. The defective mutant of tfpO (ΔtfpO) shows reductions in pilin molecular mass, surface motility and virulence towards host tobacco plants. Thus, pilin glycan plays important roles in bacterial motility and virulence. The genetic region around pilA was compared among P. syringae pathovars. The tfpO gene exists in some strains of pathovars tabaci, syringae, lachrymans, mori, actinidiae, maculicola and P. savastanoi pv. savastanoi. However, some strains of pathovars tabaci, syringae, glycinea, tomato, aesculi and oryzae do not possess tfpO, and the existence of tfpO is independent of the classification of pathovars/strains in P. syringae. Interestingly, the PilA amino acid sequences in tfpO-possessing strains show higher homology with each other than with tfpO-nonpossessing strains. These results suggest that tfpO and pilA might co-evolve in certain specific bacterial strains.

  6. Emergence and development of gut motility in the chicken embryo

    PubMed Central

    Chevalier, N. R.; Fleury, V.; Dufour, S.

    2017-01-01

    The gastrointestinal tract transports the food bolus by peristalsis. Gut motility starts at an early age in the developing embryo, well before it is required for nutrition of the organism. We present a comprehensive kinematic study of the emergence and physiological development of gut motility in all regions of the lower digestive tract of the chicken embryo from embryonic days E5 through E9. We characterized motility emergence time, propagation patterns, speed, frequency and amplitude of peristalsis waves. We found that the emergence of an uninterrupted circular ring of smooth muscle correlated with the appearance of propagative contractile waves, at E6 in the hindgut and midgut, and at E9 in the caecal appendix. We show that peristalsis at these stages is critically dependent on calcium and is not mediated by neurons as gut motility is insensitive to tetrodotoxin and takes place in the hindgut in the absence of neurons. We further demonstrate that motility also matures in ex-vivo organ culture. We compare our results to existing literature on zebrafish, mouse and human motility development, and discuss their chronological relationship with other major developmental events occurring in the chicken embryonic gut at these stages. Our work sets a baseline for further investigations of motility development in this important animal model. PMID:28222167

  7. Quorum sensing positively regulates flagellar motility in pathogenic Vibrio harveyi.

    PubMed

    Yang, Qian; Defoirdt, Tom

    2015-04-01

    Vibrios belonging to the Harveyi clade are among the major pathogens of aquatic organisms. Quorum sensing (QS) is essential for virulence of V. harveyi towards different hosts. However, most virulence factors reported to be controlled by QS to date are negatively regulated by QS, therefore suggesting that their impact on virulence is limited. In this study, we report that QS positively regulates flagellar motility. We found that autoinducer synthase mutants showed significantly lower swimming motility than the wild type, and the swimming motility could be restored by adding synthetic signal molecules. Further, motility of a luxO mutant with inactive QS (LuxO D47E) was significantly lower than that of the wild type and of a luxO mutant with constitutively maximal QS activity (LuxO D47A). Furthermore, we found that the expression of flagellar genes (both early, middle and late genes) was significantly lower in the luxO mutant with inactive QS when compared with wild type and the luxO mutant with maximal QS activity. Motility assays and gene expression also revealed the involvement of the quorum-sensing master regulator LuxR in the QS regulation of motility. Finally, the motility inhibitor phenamil significantly decreased the virulence of V. harveyi towards gnotobiotic brine shrimp larvae.

  8. Ion channels and calcium signaling in motile cilia

    PubMed Central

    Doerner, Julia F; Delling, Markus; Clapham, David E

    2015-01-01

    The beating of motile cilia generates fluid flow over epithelia in brain ventricles, airways, and Fallopian tubes. Here, we patch clamp single motile cilia of mammalian ependymal cells and examine their potential function as a calcium signaling compartment. Resting motile cilia calcium concentration ([Ca2+] ~170 nM) is only slightly elevated over cytoplasmic [Ca2+] (~100 nM) at steady state. Ca2+ changes that arise in the cytoplasm rapidly equilibrate in motile cilia. We measured CaV1 voltage-gated calcium channels in ependymal cells, but these channels are not specifically enriched in motile cilia. Membrane depolarization increases ciliary [Ca2+], but only marginally alters cilia beating and cilia-driven fluid velocity within short (~1 min) time frames. We conclude that beating of ependymal motile cilia is not tightly regulated by voltage-gated calcium channels, unlike that of well-studied motile cilia and flagella in protists, such as Paramecia and Chlamydomonas. DOI: http://dx.doi.org/10.7554/eLife.11066.001 PMID:26650848

  9. Emergence and development of gut motility in the chicken embryo.

    PubMed

    Chevalier, N R; Fleury, V; Dufour, S; Proux-Gillardeaux, V; Asnacios, A

    2017-01-01

    The gastrointestinal tract transports the food bolus by peristalsis. Gut motility starts at an early age in the developing embryo, well before it is required for nutrition of the organism. We present a comprehensive kinematic study of the emergence and physiological development of gut motility in all regions of the lower digestive tract of the chicken embryo from embryonic days E5 through E9. We characterized motility emergence time, propagation patterns, speed, frequency and amplitude of peristalsis waves. We found that the emergence of an uninterrupted circular ring of smooth muscle correlated with the appearance of propagative contractile waves, at E6 in the hindgut and midgut, and at E9 in the caecal appendix. We show that peristalsis at these stages is critically dependent on calcium and is not mediated by neurons as gut motility is insensitive to tetrodotoxin and takes place in the hindgut in the absence of neurons. We further demonstrate that motility also matures in ex-vivo organ culture. We compare our results to existing literature on zebrafish, mouse and human motility development, and discuss their chronological relationship with other major developmental events occurring in the chicken embryonic gut at these stages. Our work sets a baseline for further investigations of motility development in this important animal model.

  10. Involvement of gut microbiota in association between GLP-1/GLP-1 receptor expression and gastrointestinal motility.

    PubMed

    Yang, Mo; Fukui, Hirokazu; Eda, Hirotsugu; Xu, Xin; Kitayama, Yoshitaka; Hara, Ken; Kodani, Mio; Tomita, Toshihiko; Oshima, Tadayuki; Watari, Jiro; Miwa, Hiroto

    2017-04-01

    The microbiota in the gut is known to play a pivotal role in host physiology by interacting with the immune and neuroendocrine systems in gastrointestinal (GI) tissues. Glucagon-like peptide 1 (GLP-1), a gut hormone, is involved in metabolism as well as GI motility. We examined how gut microbiota affects the link between GLP-1/GLP-1 receptor (GLP-1R) expression and motility of the GI tract. Germ-free (GF) mice (6 wk old) were orally administered a fecal bacterial suspension prepared from specific pathogen-free (SPF) mice, and then after fecal transplantation (FT) GI tissues were obtained from the GF mice at various time points. The expression of GLP-1 and its receptor was examined by immunohistochemistry, and gastrointestinal transit time (GITT) was measured by administration of carmine red solution. GLP-1 was expressed in endocrine cells in the colonic mucosa, and GLP-1R was expressed in myenteric neural cells throughout the GI wall. GLP-1R-positive cells throughout the GI wall were significantly fewer in GF mice with FT than in GF mice without gut microbiota reconstitution. GITT was significantly shorter in GF mice with FT than in control GF mice without FT and correlated with the number of GLP-1R-positive cells throughout the GI wall. GITT was significantly longer in GF control mice than in SPF mice. When those mice were treated with GLP-1 agonist extendin4, GITT was significantly longer in the GF mice. The gut microbiota may accelerate or at least modify GI motility while suppressing GLP-1R expression in myenteric neural cells throughout the GI tract.NEW & NOTEWORTHY The gut microbiota has been intensively studied, because it plays a pivotal role in various aspects of host physiology. On the other hand, glucagon-like peptide 1 (GLP-1) plays important roles in metabolism as well as gastrointestinal motility. In the present study, we have suggested that the gut microbiota accelerates gastrointestinal motility while suppressing the expression of GLP-1 receptor in

  11. The alginate regulator AlgR and an associated sensor FimS are required for twitching motility in Pseudomonas aeruginosa.

    PubMed Central

    Whitchurch, C B; Alm, R A; Mattick, J S

    1996-01-01

    Mucoid strains of Pseudomonas aeruginosa isolated from the lungs of cystic fibrosis patients produce large amounts of the exopolysaccharide alginate. AlgR has long been considered a key regulator of alginate production, but its cognate sensor has not been identified. Here we show that AlgR is required for twitching motility, which is a form of bacterial surface translocation mediated by type 4 fimbriae. Adjacent to algR we have identified a sensor gene (fimS), which is also required for twitching motility. However, FimS does not appear to be required for alginate production in mucoid strains. FimS and AlgR are representative of a new subclass of two-component transmitter-receiver regulatory systems. The alternative sigma factor AlgU also affects both alginate production and twitching motility. Therefore, these two virulence determinants appear to be closely associated and coordinately regulated. Images Fig. 1 Fig. 2 Fig. 3 PMID:8790418

  12. Role of quorum sensing in bacterial infections.

    PubMed

    Castillo-Juárez, Israel; Maeda, Toshinari; Mandujano-Tinoco, Edna Ayerim; Tomás, María; Pérez-Eretza, Berenice; García-Contreras, Silvia Julieta; Wood, Thomas K; García-Contreras, Rodolfo

    2015-07-16

    Quorum sensing (QS) is cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached. Several lines of evidence indicate that QS enhances virulence of bacterial pathogens in animal models as well as in human infections; however, its relative importance for bacterial pathogenesis is still incomplete. In this review, we discuss the present evidence from in vitro and in vivo experiments in animal models, as well as from clinical studies, that link QS systems with human infections. We focus on two major QS bacterial models, the opportunistic Gram negative bacteria Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus, which are also two of the main agents responsible of nosocomial and wound infections. In addition, QS communication systems in other bacterial, eukaryotic pathogens, and even immune and cancer cells are also reviewed, and finally, the new approaches proposed to combat bacterial infections by the attenuation of their QS communication systems and virulence are also discussed.

  13. Role of quorum sensing in bacterial infections

    PubMed Central

    Castillo-Juárez, Israel; Maeda, Toshinari; Mandujano-Tinoco, Edna Ayerim; Tomás, María; Pérez-Eretza, Berenice; García-Contreras, Silvia Julieta; Wood, Thomas K; García-Contreras, Rodolfo

    2015-01-01

    Quorum sensing (QS) is cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached. Several lines of evidence indicate that QS enhances virulence of bacterial pathogens in animal models as well as in human infections; however, its relative importance for bacterial pathogenesis is still incomplete. In this review, we discuss the present evidence from in vitro and in vivo experiments in animal models, as well as from clinical studies, that link QS systems with human infections. We focus on two major QS bacterial models, the opportunistic Gram negative bacteria Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus, which are also two of the main agents responsible of nosocomial and wound infections. In addition, QS communication systems in other bacterial, eukaryotic pathogens, and even immune and cancer cells are also reviewed, and finally, the new approaches proposed to combat bacterial infections by the attenuation of their QS communication systems and virulence are also discussed. PMID:26244150

  14. Utility of the wireless motility capsule and lactulose breath testing in the evaluation of patients with Parkinson's disease who present with functional gastrointestinal symptoms

    PubMed Central

    Su, Andrew; Gandhy, Rita; Barlow, Carrolee; Triadafilopoulos, George

    2017-01-01

    Background The aetiology and origin of gastrointestinal symptoms in Parkinson's disease (PD) remains poorly understood. Gastroparesis, small bowel transit delay and bacterial overgrowth may, individually or collectively, play a role. Aims In patients with PD and functional gastrointestinal symptoms, we aimed to determine the utility of the wireless motility capsule and lactulose breath tests in further defining their symptoms' aetiology. Methods In this retrospective cohort study, consecutive patients with PD and functional gastrointestinal symptoms underwent clinical assessment, as well as wireless motility capsule and lactulose breath testing using standard protocols. Results We studied 65 patients with PD and various gastrointestinal symptoms. 35% exhibited gastroparesis by the wireless motility capsule study, 20% small bowel transit delay, while 8% had combined transit abnormalities, suggestive of overlapping gastric and small bowel dysmotility. Small bowel bacterial overgrowth was seen in 34% of cases. Symptoms of abdominal pain, regurgitation, bloating, nausea, vomiting, belching and weight loss could not distinguish between patients with or without gastroparesis, although bloating was significantly more prominent (p<0.001) overall and specifically more so in patients with slow small bowel transit (p<0.01). There was no relationship between delayed small bowel transit time and bacterial overgrowth (p=0.5); PD scores and duration were not correlated with either the transit findings or small bowel bacterial overgrowth. Conclusions Functional gastrointestinal symptoms in patients with PD may reflect gastroparesis, small bowel transit delay or both, suggesting motor and/or autonomic dysfunction, and may be associated with small bowel bacterial overgrowth. The wireless motility capsule and lactulose breath testing are non-invasive and useful in the assessment of these patients. PMID:28321329

  15. Swimming with protists: perception, motility and flagellum assembly.

    PubMed

    Ginger, Michael L; Portman, Neil; McKean, Paul G

    2008-11-01

    In unicellular and multicellular eukaryotes, fast cell motility and rapid movement of material over cell surfaces are often mediated by ciliary or flagellar beating. The conserved defining structure in most motile cilia and flagella is the '9+2' microtubule axoneme. Our general understanding of flagellum assembly and the regulation of flagellar motility has been led by results from seminal studies of flagellate protozoa and algae. Here we review recent work relating to various aspects of protist physiology and cell biology. In particular, we discuss energy metabolism in eukaryotic flagella, modifications to the canonical assembly pathway and flagellum function in parasite virulence.

  16. Motility, Force Generation, and Energy Consumption of Unicellular Parasites.

    PubMed

    Hochstetter, Axel; Pfohl, Thomas

    2016-07-01

    Motility is a key factor for pathogenicity of unicellular parasites, enabling them to infiltrate and evade host cells, and perform several of their life-cycle events. State-of-the-art methods of motility analysis rely on a combination of optical tweezers with high-resolution microscopy and microfluidics. With this technology, propulsion forces, energies, and power generation can be determined so as to shed light on the motion mechanisms, chemotactic behavior, and specific survival strategies of unicellular parasites. With these new tools in hand, we can elucidate the mechanisms of motility and force generation of unicellular parasites, and identify ways to manipulate and eventually inhibit them.

  17. Effects of trifluoromethyl ketones on the motility of Proteus vulgaris.

    PubMed

    Wolfart, Krisztina; Molnar, Annamaria; Kawase, Masami; Motohashi, Noboru; Molnar, Joseph

    2004-09-01

    In the present study, we showed the inhibition of motility by trifluoromethyl ketone (TF) derivatives (1-8) in Proteus vulgaris (P. vulgaris) cultures. Among them, 1-(2-benzoxazoyl)-3,3,3-trifluoro-2-propanone (1) showed a much stronger inhibitory effect on the motility of P. vulgaris than other TF compounds at 10% MIC. Our results suggest the possibility of an inhibitory action of TF compounds on the proton motive forces by affecting the action of biological motor and proton efflux in the membranes, resulting in a reduction of the ratio of running and the increased number of tumbling and non-motile cells.

  18. The Chicago classification of motility disorders: an update.

    PubMed

    Roman, Sabine; Gyawali, C Prakash; Xiao, Yinglian; Pandolfino, John E; Kahrilas, Peter J

    2014-10-01

    The Chicago Classification defines esophageal motility disorders in high resolution manometry. This is based on individual scoring of 10 swallows performed in supine position. Disorders of esophago-gastric junction (EGJ) outflow obstruction are defined by a median integrated relaxation pressure above the limit of normal and divided into 3 achalasia subtypes and EGJ outflow obstruction. Major motility disorders (aperistalsis, distal esophageal spasm, and hypercontractile esophagus) are patterns not encountered in controls in the context of normal EGJ relaxation. Finally with the latest version of the Chicago Classification, only two minor motor disorders are considered: ineffective esophageal motility and fragmented peristalsis.

  19. Colloidal motility and patterning by physical chemotaxis

    NASA Astrophysics Data System (ADS)

    Palacci, Jeremie; Abecassis, Benjamin; Cottin-Bizonne, Cecile; Ybert, Christophe; Bocquet, Lyderic

    2009-11-01

    We developped a microfluidic setup to show the motility of colloids or biomolecules under a controlled salt gradient thanks to the diffusiophoresis phenomenon [1,2]. We can therefore mimic chemotaxis on simple physical basis with thrilling analogies with the biological chemotaxis of E. Coli bacteria: salt dependance of the velocity [3] and log-sensing behavior [4]. In addition with a temporally tunable gradient we show we can generate an effective osmotic potential to trap colloids or DNA. These experimental observations are supported by numerical simulations and an asymptotic ratchet model. Finally, we use these traps to generate various patterns and because concentration gradients are ubiquitous in nature, we question for the role of such a mecanism in morphogenesis [5] or positioning perspectives in cells [6]. [4pt] [1] B. Abecassis, C. Cottin-Bizonne, C. Ybert, A. Ajdari, and L. Bocquet, Nat. Mat., 7(10):785--789, 2008. [2] Anderson, Ann. Rev. Fluid Mech, 21, 1989. [3] Y. L. Qi and J. Adler, PNAS, 86(21):8358--8362, 1989. [4] Y. V. Kalinin, L. L. Jiang, Y. H. Tu, and M. M. Wu, Biophys. J., 96(6):2439--2448, 2009. [4] J. B. Moseley, A. Mayeux, A. Paoletti, and P. Nurse, Nat., 459(7248):857--U8, 2009. [6] L. Wolpert, Dev., 107:3--12, 1989

  20. Activated Membrane Patches Guide Chemotactic Cell Motility

    PubMed Central

    Hecht, Inbal; Skoge, Monica L.; Charest, Pascale G.; Ben-Jacob, Eshel; Firtel, Richard A.; Loomis, William F.; Levine, Herbert; Rappel, Wouter-Jan

    2011-01-01

    Many eukaryotic cells are able to crawl on surfaces and guide their motility based on environmental cues. These cues are interpreted by signaling systems which couple to cell mechanics; indeed membrane protrusions in crawling cells are often accompanied by activated membrane patches, which are localized areas of increased concentration of one or more signaling components. To determine how these patches are related to cell motion, we examine the spatial localization of RasGTP in chemotaxing Dictyostelium discoideum cells under conditions where the vertical extent of the cell was restricted. Quantitative analyses of the data reveal a high degree of spatial correlation between patches of activated Ras and membrane protrusions. Based on these findings, we formulate a model for amoeboid cell motion that consists of two coupled modules. The first module utilizes a recently developed two-component reaction diffusion model that generates transient and localized areas of elevated concentration of one of the components along the membrane. The activated patches determine the location of membrane protrusions (and overall cell motion) that are computed in the second module, which also takes into account the cortical tension and the availability of protrusion resources. We show that our model is able to produce realistic amoeboid-like motion and that our numerical results are consistent with experimentally observed pseudopod dynamics. Specifically, we show that the commonly observed splitting of pseudopods can result directly from the dynamics of the signaling patches. PMID:21738453

  1. Structures of the Toxoplasma gliding motility adhesin

    PubMed Central

    Song, Gaojie; Springer, Timothy A.

    2014-01-01

    Micronemal protein 2 (MIC2) is the key adhesin that supports gliding motility and host cell invasion by Toxoplasma gondii. With a von Willebrand factor A (VWA) domain and six thrombospondin repeat domains (TSR1–6) in its ectodomain, MIC2 connects to the parasite actomyosin system through its cytoplasmic tail. MIC2-associated protein (M2AP) binds noncovalently to the MIC2 ectodomain. MIC2 and M2AP are stored in micronemes as proforms. We find that the MIC2–M2AP ectodomain complex is a highly elongated 1:1 monomer with M2AP bound to the TSR6 domain. Crystal structures of N-terminal fragments containing the VWA and TSR1 domains for proMIC2 and MIC2 reveal a closed conformation of the VWA domain and how it associates with the TSR1 domain. A long, proline-rich, disulfide-bonded pigtail loop in TSR1 overlaps the VWA domain. Mannose α-C-linked to Trp-276 in TSR1 has an unusual 1C4 chair conformation. The MIC2 VWA domain includes a mobile α5-helix and a 22-residue disordered region containing two disulfide bonds in place of an α6-helix. A hydrophobic residue in the prodomain binds to a pocket adjacent to the α7-helix that pistons in opening of the VWA domain to a putative high-affinity state. PMID:24639528

  2. Eye Motility Alterations in Retinitis Pigmentosa.

    PubMed

    Migliorini, Raffaele; Comberiati, Anna Maria; Galeoto, Giovanni; Fratipietro, Manuela; Arrico, Loredana

    2015-01-01

    Purpose. We evaluated a sample of individuals with retinitis pigmentosa (RP) with the aim of assessing the presence or absence of ocular motility (OM) disorders. Materials and Methods. We included 23 out of the 25 individuals from the sample (9 females and 14 males) with an average visual acuity of 6/10. Results. The cover test about the vertical deviation in near distance showed an r/l in 3.45% and an l/r in 6.9%. The assessment of OM showed that 39.1% of the sample had a severe hyperfunction of the IO of the right eye and a severe hyperfunction (34.5%) of the SO of the left eye; 21.8% had a moderate hypofunction of right SO with a moderate percentage of hypofunction of 17.5% for the SO of the left eye; 30.5%, however, showed a serious hypofunction of the SR of both eyes; 21.7% of the sample showed a hyperfunction in both eyes of the IR. Conclusion. This alteration, however, is not attributable to either a high refractive defect (medium-low myopia: -1 diopter ±3 SD) or to a severely impaired binocular vision (visual acuity, motor fusion, and stereopsis are normal or within a range of values commonly accepted). Therefore, the disorders of OM lead to a genetic origin.

  3. Tachykinins and in vivo gut motility.

    PubMed

    Sarna, S K

    1999-08-01

    The gut smooth muscle in the intact conscious state exhibits three distinct types of contractions: rhythmic phasic contractions, tone, and ultrapropulsive contractions. The motility functions of these contractions differ markedly. The phasic contractions mix and propel the ingested food in an orderly fashion so that the nutrients can be absorbed. The ultrapropulsive contractions are of two types, giant migrating contractions (GMCs) and retrograde giant contractions (RGCs). GMCs produce mass movements in the caudal direction and RGCs in the oral direction. GMCs are associated with the symptoms of diarrhea, abdominal cramping, tenesmus, and urgency of defecation. The RGCs regurgitate the contents of the upper small intestine into the stomach in preparation of their expulsion by the somatomotor response. Tachykinins and their receptors are strategically located on the enteric neurons and smooth muscle cells to regulate the above contractions. Recent findings show that NK-1 receptors located on colonic circular smooth muscle cells may mediate colonic GMCs, whereas NK-3 receptors located on presynaptic neurons may mediate the small intestinal GMCs. The molecular and cellular mechanisms of stimulation of RGCs are not known. NK-1 receptor antagonists have shown potential therapeutic effects on vomiting induced by a variety of stimuli in experimental animals.

  4. Utility of wireless motility capsule and lactulose breath testing in the evaluation of patients with chronic functional bloating

    PubMed Central

    Triadafilopoulos, George

    2016-01-01

    Background The precise aetiology of chronic bloating remains poorly understood and underlying gastroparesis, small bowel bacterial overgrowth and colonic inertia may, individually or collectively, play a role. Aims In this retrospective cohort analysis of symptomatic patients with chronic persistent bloating, we determined the clinical utility of wireless motility capsule and lactulose breath test in further defining the underlying aetiology for functional bloating. Methods Consecutive patients with chronic bloating underwent clinical assessment, wireless motility capsule testing and lactulose breath testing using standard protocols. Results 52 patients qualified for inclusion in this analysis, fulfilling Rome III criteria for functional bloating. Most patients (54%) had an abnormal wireless motility capsule study; of those, 11.5% had evidence of gastroparesis, 7.7% had small bowel transit delay, 15.8% had colonic inertia, 3.8% had delayed gastric and small bowel transit, 5.6% had combined gastric and colonic transit delay, 3.8% had delayed small bowel and colonic transit, and 5.6% had delayed gastric, small bowel and colon transit times. Using clinical questionnaires the median scores for bloating, constipation and eructation were not significantly different. Neither constipation nor eructation was specific to gastroparesis or colonic inertia but bloating was numerically more prevalent and severe in patients with delayed small bowel transit. 40% of patients had positive lactulose breath test but had no distinguishing clinical characteristics. Conclusions Chronic functional bloating may reflect underlying gastroparesis, small intestinal bacterial overgrowth or colonic inertia. Wireless motility capsule and lactulose breath test are useful in the assessment of patients with bloating and should be considered during evaluation. PMID:27648298

  5. Vibrio fischeri flagellin A is essential for normal motility and for symbiotic competence during initial squid light organ colonization.

    PubMed

    Millikan, Deborah S; Ruby, Edward G

    2004-07-01

    The motile bacterium Vibrio fischeri is the specific bacterial symbiont of the Hawaiian squid Euprymna scolopes. Because motility is essential for initiating colonization, we have begun to identify stage-specific motility requirements by creating flagellar mutants that have symbiotic defects. V. fischeri has six flagellin genes that are uniquely arranged in two chromosomal loci, flaABCDE and flaF. With the exception of the flaA product, the predicted gene products are more similar to each other than to flagellins of other Vibrio species. Immunoblot analysis indicated that only five of the six predicted proteins were present in purified flagella, suggesting that one protein, FlaF, is unique with respect to either its regulation or its function. We created mutations in two genes, flaA and flaC. Compared to a flaC mutant, which has wild-type flagellation, a strain having a mutation in the flaA gene has fewer flagella per cell and exhibits a 60% decrease in its rate of migration in soft agar. During induction of light organ symbiosis, colonization by the flaA mutant is impaired, and this mutant is severely outcompeted when it is presented to the animal as a mixed inoculum with the wild-type strain. Furthermore, flaA mutant cells are preferentially expelled from the animal, suggesting either that FlaA plays a role in adhesion or that normal motility is an advantage for retention within the host. Taken together, these results show that the flagellum of V. fischeri is a complex structure consisting of multiple flagellin subunits, including FlaA, which is essential both for normal flagellation and for motility, as well as for effective symbiotic colonization.

  6. A 20-year perspective--from Journal of Gastrointestinal Motility to Neurogastroenterology and Motility.

    PubMed

    Wingate, D L

    2008-05-01

    This review traces the origins of this journal as the consequence of a revolution in academic publishing that started in Oxford 50 years ago. It also traces the expansion of the field of gastrointestinal motility by the development of new methodology that prompted both the creation of learned societies and a role for a journal devoted to this field. The problems that arose because the new journal was an 'orphan journal' lacking a parent society are recounted, as are the events that eventually led to its adoption. Finally, the introduction of the term 'neurogastroenterology' into scientific and clinical parlance is explained.

  7. Optical approaches to the study of foraminiferan motility.

    PubMed

    Travis, J L; Bowser, S S

    1988-01-01

    Microtubules are the major cytoskeletal component of foraminiferan reticulopodia. Video-enhanced differential interference contrast light microscopy has demonstrated that the microtubules serve as the intracellular tracks along which rapid bidirectional organelle transport and cell surface motility occurs. Microtubules appear to move, both axially and laterally within the pseudopodial cytoplasm, and these microtubule translocations appear to drive the various reticulopodial movements. F-actin is localized to discrete filament plaques form at sites of pseudopod-substrate adhesion. Correlative immunofluorescence and electron microscopy reveals a structural interaction between microtubules and the actin-containing filament plaques. Our recent data on reticulopodial motility are discussed in an historical context, and a model for foram motility, based on motile microtubules, is presented.

  8. A novel putrescine importer required for type 1 pili-driven surface motility induced by extracellular putrescine in Escherichia coli K-12.

    PubMed

    Kurihara, Shin; Suzuki, Hideyuki; Oshida, Mayu; Benno, Yoshimi

    2011-03-25

    Recently, many studies have reported that polyamines play a role in bacterial cell-to-cell signaling processes. The present study describes a novel putrescine importer required for induction of type 1 pili-driven surface motility. The surface motility of the Escherichia coli ΔspeAB ΔspeC ΔpotABCD strain, which cannot produce putrescine and cannot import spermidine from the medium, was induced by extracellular putrescine. Introduction of the gene deletions for known polyamine importers (ΔpotE, ΔpotFGHI, and ΔpuuP) or a putative polyamine importer (ΔydcSTUV) into the ΔspeAB ΔspeC ΔpotABCD strain did not affect putrescine-induced surface motility. The deletion of yeeF, an annotated putative putrescine importer, in the ΔspeAB ΔspeC ΔpotABCD ΔydcSTUV strain abolished surface motility in putrescine-supplemented medium. Complementation of yeeF by a plasmid vector restored surface motility. The surface motility observed in the present study was abolished by the deletion of fimA, suggesting that the surface motility is type 1 pili-driven. A transport assay using the yeeF(+) or ΔyeeF strains revealed that YeeF is a novel putrescine importer. The K(m) of YeeF (155 μM) is 40 to 300 times higher than that of other importers reported previously. On the other hand, the V(max) of YeeF (9.3 nmol/min/mg) is comparable to that of PotABCD, PotFGHI, and PuuP. The low affinity of YeeF for putrescine may allow E. coli to sense the cell density depending on the concentration of extracellular putrescine.

  9. Influence of lysogeny of Tectiviruses GIL01 and GIL16 on Bacillus thuringiensis growth, biofilm formation, and swarming motility.

    PubMed

    Gillis, Annika; Mahillon, Jacques

    2014-12-01

    Bacillus thuringiensis is an entomopathogenic bacterium that has been used as an efficient biopesticide worldwide. Despite the fact that this bacterium is usually described as an insect pathogen, its life cycle in the environment is still largely unknown. B. thuringiensis belongs to the Bacillus cereus group of bacteria, which has been associated with many mobile genetic elements, such as species-specific temperate or virulent bacteriophages (phages). Temperate (lysogenic) phages are able to establish a long-term relationship with their host, providing, in some cases, novel ecological traits to the bacterial lysogens. Therefore, this work focuses on evaluating the potential influence of temperate tectiviruses GIL01 and GIL16 on the development of different life traits of B. thuringiensis. For this purpose, a B. thuringiensis serovar israelensis plasmid-cured (nonlysogenic) strain was used to establish bacterial lysogens for phages GIL01 and GIL16, and, subsequently, the following life traits were compared among the strains: kinetics of growth, metabolic profiles, antibiotics susceptibility, biofilm formation, swarming motility, and sporulation. The results revealed that GIL01 and GIL16 lysogeny has a significant influence on the bacterial growth, sporulation rate, biofilm formation, and swarming motility of B. thuringiensis. No changes in metabolic profiles or antibiotic susceptibilities were detected. These findings provide evidence that tectiviruses have a putative role in the B. thuringiensis life cycle as adapters of life traits with ecological advantages.

  10. Influence of Lysogeny of Tectiviruses GIL01 and GIL16 on Bacillus thuringiensis Growth, Biofilm Formation, and Swarming Motility

    PubMed Central

    Gillis, Annika

    2014-01-01

    Bacillus thuringiensis is an entomopathogenic bacterium that has been used as an efficient biopesticide worldwide. Despite the fact that this bacterium is usually described as an insect pathogen, its life cycle in the environment is still largely unknown. B. thuringiensis belongs to the Bacillus cereus group of bacteria, which has been associated with many mobile genetic elements, such as species-specific temperate or virulent bacteriophages (phages). Temperate (lysogenic) phages are able to establish a long-term relationship with their host, providing, in some cases, novel ecological traits to the bacterial lysogens. Therefore, this work focuses on evaluating the potential influence of temperate tectiviruses GIL01 and GIL16 on the development of different life traits of B. thuringiensis. For this purpose, a B. thuringiensis serovar israelensis plasmid-cured (nonlysogenic) strain was used to establish bacterial lysogens for phages GIL01 and GIL16, and, subsequently, the following life traits were compared among the strains: kinetics of growth, metabolic profiles, antibiotics susceptibility, biofilm formation, swarming motility, and sporulation. The results revealed that GIL01 and GIL16 lysogeny has a significant influence on the bacterial growth, sporulation rate, biofilm formation, and swarming motility of B. thuringiensis. No changes in metabolic profiles or antibiotic susceptibilities were detected. These findings provide evidence that tectiviruses have a putative role in the B. thuringiensis life cycle as adapters of life traits with ecological advantages. PMID:25261525

  11. Tubulin protofilaments and kinesin-dependent motility

    PubMed Central

    1992-01-01

    . This indicates that even if these microtubules differ in surface lattice, this does not affect the motility. PMID:1500429

  12. Evaluation of regional and whole gut motility using the wireless motility capsule: relevance in clinical practice

    PubMed Central

    Tran, Khoa; Brun, Rita

    2012-01-01

    The wireless motility capsule (WMC) is an ambulatory noninvasive and nonradioactive diagnostic sensor that continuously samples intraluminal pH, temperature, and pressure as it moves through the gastrointestinal (GI) tract. This review summarizes the data obtained in clinical trials with the WMC and discusses its role in clinical practice. The United States Food and Drug Administration has approved the SmartPill GI monitoring system for the evaluation of gastric emptying time in patients with suspected gastroparesis, the evaluation of colonic transit time in patients with suspected chronic constipation, and for the characterization of pressure profiles from the antrum and duodenum. Clinical studies have shown that WMC-measured GI transit times can distinguish patients with motility abnormalities similarly to conventional testing. However, the WMC offers the advantage of providing a full GI-tract profile, enabling the detection of multiregional GI transit abnormalities in patients with suspected upper or lower GI dysmotility. The WMC also characterizes pressure profiles of the GI tract and impaired pressure profile limits are reported for the antrum and duodenum. In comparison with manometry, interpretations of pressure measurements obtained by the WMC are limited by an inability to detect a peristaltic pressure wave front, and further investigation is required to develop clinical applications. Clinical studies with the WMC indicated that it should be considered for the evaluation of regional and whole gut transit time in patients with suspected upper or lower dysmotility, particularly if there are concerns about multiregional dysmotility. PMID:22778790

  13. Effect of surface chemistry on in vitro actomyosin motility

    NASA Astrophysics Data System (ADS)

    Hanson, Kristi L.; Solana, Gerardin; Nicolau, Dan V.

    2005-02-01

    A variety of surface coatings were evaluated for their ability to promote in vitro actomyosin motility. Rabbit skeletal muscle heavy meromyosin (HMM) was adsorbed to uncoated glass and to surfaces coated with nitrocellulose, poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), poly(tert-butyl methacrylate (PtBMA), polystyrene (PS) and hexamethyldisilazane (HMDS), and the myosin driven movement of fluorescently labeled actin filaments was recorded using epifluorescence microscopy. HMDS and uncoated glass did not support actomyosin motility, while mean velocities on other surfaces ranged from 1.7 μm sec-1 (PtBMA) to 3.5 μm sec-1 (NC). Nitrocellulose supported the highest proportion of motile filaments (75%), while 47 - 61% of filaments were motile on other surfaces. Within the methacrylate polymers, average filament velocities increased with decreasing hydrophobicity of the surface. Distributions of instantaneous acceleration values and angle deviations suggested more erratic and stuttered movement on the methacrylates and polystyrene than on NC, in line with qualitative visual observations. Despite the higher velocities and high proportion of motile filaments on NC, this surface resulted in a high proportion of small filaments and high rates of filament breakage during motility. Similar effects were observed on PS and PtBMA, while PBMA and PMMA supported longer filaments with less observed breakage.

  14. Entropy-driven motility of Sinorhizobium meliloti on a semi-solid surface.

    PubMed

    Dilanji, Gabriel E; Teplitski, Max; Hagen, Stephen J

    2014-06-07

    Sinorhizobium meliloti growing on soft agar can exhibit an unusual surface spreading behaviour that differs from other bacterial surface motilities. Bacteria in the colony secrete an exopolysaccharide-rich mucoid fluid that expands outward on the surface, carrying within it a suspension of actively dividing cells. The moving slime disperses the cells in complex and dynamic patterns indicative of simultaneous bacterial growth, swimming and aggregation. We find that while flagellar swimming is required to maintain the cells in suspension, the spreading and the associated pattern formation are primarily driven by the secreted exopolysaccharide EPS II, which creates two entropy-increasing effects: an osmotic flow of water from the agar to the mucoid fluid and a crowding or depletion attraction between the cells. Activation of these physical/chemical phenomena may be a useful function for the high molecular weight EPS II, a galactoglucan whose biosynthesis is tightly regulated by the ExpR/SinI/SinR quorum-sensing system: unlike bacterial colonies that spread via bacterium-generated, physical propulsive forces, S. meliloti under quorum conditions may use EPS II to activate purely entropic forces within its environment, so that it can disperse by passively 'surfing' on those forces.

  15. Entropy-driven motility of Sinorhizobium meliloti on a semi-solid surface

    PubMed Central

    Dilanji, Gabriel E.; Teplitski, Max; Hagen, Stephen J.

    2014-01-01

    Sinorhizobium meliloti growing on soft agar can exhibit an unusual surface spreading behaviour that differs from other bacterial surface motilities. Bacteria in the colony secrete an exopolysaccharide-rich mucoid fluid that expands outward on the surface, carrying within it a suspension of actively dividing cells. The moving slime disperses the cells in complex and dynamic patterns indicative of simultaneous bacterial growth, swimming and aggregation. We find that while flagellar swimming is required to maintain the cells in suspension, the spreading and the associated pattern formation are primarily driven by the secreted exopolysaccharide EPS II, which creates two entropy-increasing effects: an osmotic flow of water from the agar to the mucoid fluid and a crowding or depletion attraction between the cells. Activation of these physical/chemical phenomena may be a useful function for the high molecular weight EPS II, a galactoglucan whose biosynthesis is tightly regulated by the ExpR/SinI/SinR quorum-sensing system: unlike bacterial colonies that spread via bacterium-generated, physical propulsive forces, S. meliloti under quorum conditions may use EPS II to activate purely entropic forces within its environment, so that it can disperse by passively ‘surfing’ on those forces. PMID:24741008

  16. Effect of tannic and gallic acids alone or in combination with carbenicillin or tetracycline on Chromobacterium violaceum CV026 growth, motility, and biofilm formation.

    PubMed

    Dusane, Devendra H; O'May, Che; Tufenkji, Nathalie

    2015-07-01

    Chromobacterium violaceum is an opportunistic pathogen that causes infections that are difficult to treat. The goal of this research was to evaluate the effect of selected tannins (tannic acid (TA) and gallic acid (GA)) on bacterial growth, motility, antibiotic (carbenicillin, tetracycline) susceptibility, and biofilm formation. Both tannins, particularly TA, impaired bacterial growth levels and swimming motilities at sub-minimum inhibitory concentrations (sub-MICs). In combination with tannins, antibiotics showed increased MICs, suggesting that tannins interfered with antibacterial activity. Sub-MICs of tetracycline or TA alone enhanced biofilm formation of C. violaceum; however, in combination, these compounds inhibited biofilm formation. In contrast, carbenicillin at sub-MICs was effective in inhibiting C. violaceum biofilm formation; however, in combination with lower concentrations of TA or GA, biofilms were enhanced. These results provide insights into the effects of tannins on C. violaceum growth and their varying interaction with antibiotics used to target C. violaceum infections.

  17. Chemotaxis of bacteria in glass capillary arrays. Escherichia coli, motility, microchannel plate, and light scattering.

    PubMed

    Berg, H C; Turner, L

    1990-10-01

    Random and directed motility of bacterial populations were assayed by monitoring the flux of bacteria through a microchannel plate (a porous glass plate comprising a fused array of capillary tubes) separating two identical stirred chambers. Cells, washed free of growth medium by a new filtration method, were added to one chamber at a low density. Their number in the other chamber was determined from the amount of light scattered from a beam of a laser diode and recorded on a strip chart. Diffusion coefficients were computed from fluxes observed in the absence of chemical gradients, and chemotaxis drift velocities were computed from fluxes observed in their presence. Cells migrated through tubes of diam 10 microns more rapidly than through tubes of diam 50 microns, suggesting that the straight segments of their tracks were aligned with the axes of the smaller tubes. Mutants that are motile but nonchemotactic could be selected because they move through the microchannel plate in the face of an adverse gradient. Weak chemotactic responses were assessed from ratios of fluxes observed in paired experiments in which the sign of the gradient of attractant was reversed. Studies were made of wild-type Escherichia coli and mutants that are nonmotile, tumblely, smooth-swimming, aspartate-blind, or defective in methylation and demethylation. Chemotaxis drift velocities for the latter mutants (cheRcheB) were quite small.

  18. Motility modulation by the small non-coding RNA SroC in Salmonella Typhimurium.

    PubMed

    Fuentes, Danitza N; Calderón, Paulina F; Acuña, Lillian G; Rodas, Paula I; Paredes-Sabja, Daniel; Fuentes, Juan A; Gil, Fernando; Calderón, Iván L

    2015-09-01

    Bacterial regulatory networks of gene expression include the interaction of diverse types of molecules such as the small non-coding RNAs (sRNAs) and their cognate messenger RNAs (mRNAs). In this study, we demonstrated that the Salmonella Typhimurium sRNA SroC is significantly expressed between the late-exponential and stationary phase of growth in an rpoS-dependent manner. The expression of flagellar genes predicted as targets of this sRNA was quantitatively analyzed in both a ΔsroC mutant and a SroC-overexpressing (pSroC) strain. Deletion of sroC increased flagellar gene expression (i.e. flhBAE and fliE). Conversely, overexpression of SroC reduced flhBAE and fliE expression. These observations correlated with phenotypic evaluation of motility, where sroC deletion slightly increased motility, which in turn, was drastically reduced upon overexpression of SroC. The effects of deletion and overexpression of sroC in biofilm formation were also examined, where the ΔsroC and pSroC strains exhibited a reduced and increased ability to form biofilm, respectively. Furthermore, electron microscopy revealed that the wild-type strain overexpressing SroC had a non-flagellated phenotype. Taken together, our results showed that S. Typhimurium sRNA SroC modulates the flagellar synthesis by down-regulating the expression of flhBAE and fliE genes.

  19. FlgN Is Required for Flagellum-Based Motility by Bacillus subtilis

    PubMed Central

    Cairns, Lynne S.; Marlow, Victoria L.; Kiley, Taryn B.; Birchall, Christopher; Ostrowski, Adam; Aldridge, Phillip D.

    2014-01-01

    The assembly of the bacterial flagellum is exquisitely controlled. Flagellar biosynthesis is underpinned by a specialized type III secretion system that allows export of proteins from the cytoplasm to the nascent structure. Bacillus subtilis regulates flagellar assembly using both conserved and species-specific mechanisms. Here, we show that YvyG is essential for flagellar filament assembly. We define YvyG as an orthologue of the Salmonella enterica serovar Typhimurium type III secretion system chaperone, FlgN, which is required for the export of the hook-filament junction proteins, FlgK and FlgL. Deletion of flgN (yvyG) results in a nonmotile phenotype that is attributable to a decrease in hag translation and a complete lack of filament polymerization. Analyses indicate that a flgK-flgL double mutant strain phenocopies deletion of flgN and that overexpression of flgK-flgL cannot complement the motility defect of a ΔflgN strain. Furthermore, in contrast to previous work suggesting that phosphorylation of FlgN alters its subcellular localization, we show that mutation of the identified tyrosine and arginine FlgN phosphorylation sites has no effect on motility. These data emphasize that flagellar biosynthesis is differentially regulated in B. subtilis from classically studied Gram-negative flagellar systems and questions the biological relevance of some posttranslational modifications identified by global proteomic approaches. PMID:24706744

  20. Evaporation-driven convection observed in a suspension of non-motile bacteria

    NASA Astrophysics Data System (ADS)

    Dunstan, Jocelyn; Lee, Kyoung Jin; Park, Simon; Goldstein, Raymond E.

    2015-03-01

    We report a novel form of convection in a suspension of non-motile bioluminescent bacteria. The patterns appear like those of conventional bioconvection driven by oxygentaxis, yet the bacteria are observed to have limited if any motility. While the phenomenon also resembles chemo-convection, in which a chemical reaction (or metabolic activity) alters the local buoyancy balance at the air-water interface, the convention actually derives from evaporation of the salty bacterial growth medium. We corroborate this through control experiments using polystyrene beads in pure and salty water, and establish that there is a threshold of salt concentration needed to observe plumes. The dynamics of the plumes is rich, with striking coalescence events and a complex internal structure. A mathematical model is formulated for the process and studied analytically and numerically, reproducing most of the observed experimental features. Evaporation-driven convection on the millimeter scale has not been studied extensively and its effect may have been underestimated in a variety of contexts. It may naturally occur in marine settings.

  1. Cathepsin E Deficiency Ameliorates Graft-versus-Host Disease and Modifies Dendritic Cell Motility

    PubMed Central

    Mengwasser, Jörg; Babes, Liane; Cordes, Steffen; Mertlitz, Sarah; Riesner, Katarina; Shi, Yu; McGearey, Aleixandria; Kalupa, Martina; Reinheckel, Thomas; Penack, Olaf

    2017-01-01

    Microbial products influence immunity after allogeneic hematopoietic stem cell transplantation (allo-SCT). In this context, the role of cathepsin E (Ctse), an aspartate protease known to cleave bacterial peptides for antigen presentation in dendritic cells (DCs), has not been studied. During experimental acute graft-versus-host disease (GVHD), we found infiltration by Ctse-positive immune cells leading to higher Ctse RNA- and protein levels in target organs. In Ctse-deficient allo-SCT recipients, we found ameliorated GVHD, improved survival, and lower numbers of tissue-infiltrating DCs. Donor T cell proliferation was not different in Ctse-deficient vs. wild-type allo-SCT recipients in MHC-matched and MHC-mismatched models. Furthermore, Ctse-deficient DCs had an intact ability to induce allogeneic T cell proliferation, suggesting that its role in antigen presentation may not be the main mechanism how Ctse impacts GVHD. We found that Ctse deficiency significantly decreases DC motility in vivo, reduces adhesion to extracellular matrix (ECM), and diminishes invasion through ECM. We conclude that Ctse has a previously unrecognized role in regulating DC motility that possibly contributes to reduced DC counts and ameliorated inflammation in GVHD target organs of Ctse-deficient allo-SCT recipients. However, our data do not provide definite proof that the observed effect of Ctse−/− deficiency is exclusively mediated by DCs. A contribution of Ctse−/−-mediated functions in other recipient cell types, e.g., macrophages, cannot be excluded. PMID:28298913

  2. Vibrio cholerae use pili and flagella synergistically to effect motility switching and conditional surface attachment

    NASA Astrophysics Data System (ADS)

    Utada, Andrew S.; Bennett, Rachel R.; Fong, Jiunn C. N.; Gibiansky, Maxsim L.; Yildiz, Fitnat H.; Golestanian, Ramin; Wong, Gerard C. L.

    2014-09-01

    We show that Vibrio cholerae, the causative agent of cholera, use their flagella and mannose-sensitive hemagglutinin (MSHA) type IV pili synergistically to switch between two complementary motility states that together facilitate surface selection and attachment. Flagellar rotation counter-rotates the cell body, causing MSHA pili to have periodic mechanical contact with the surface for surface-skimming cells. Using tracking algorithms at 5 ms resolution we observe two motility behaviours: ‘roaming', characterized by meandering trajectories, and ‘orbiting’, characterized by repetitive high-curvature orbits. We develop a hydrodynamic model showing that these phenotypes result from a nonlinear relationship between trajectory shape and frictional forces between pili and the surface: strong pili-surface interactions generate orbiting motion, increasing the local bacterial loiter time. Time-lapse imaging reveals how only orbiting mode cells can attach irreversibly and form microcolonies. These observations suggest that MSHA pili are crucial for surface selection, irreversible attachment, and ultimately microcolony formation.

  3. Influence of the molybdenum cofactor biosynthesis on anaerobic respiration, biofilm formation and motility in Burkholderia thailandensis.

    PubMed

    Andreae, Clio A; Titball, Richard W; Butler, Clive S

    2014-01-01

    Burkholderia thailandensis is closely related to Burkholderia pseudomallei, a bacterial pathogen and the causative agent of melioidosis. B. pseudomallei can survive and persist within a hypoxic environment for up to one year and has been shown to grow anaerobically in the presence of nitrate. Currently, little is known about the role of anaerobic respiration in pathogenesis of melioidosis. Using B. thailandensis as a model, a library of 1344 transposon mutants was created to identify genes required for anaerobic nitrate respiration. One transposon mutant (CA01) was identified with an insertion in BTH_I1704 (moeA), a gene required for the molybdopterin biosynthetic pathway. This pathway is involved in the synthesis of a molybdopterin cofactor required for a variety of molybdoenzymes, including nitrate reductase. Disruption of molybdopterin biosynthesis prevented growth under anaerobic conditions, when using nitrate as the sole terminal electron acceptor. Defects in anaerobic respiration, nitrate reduction, motility and biofilm formation were observed for CA01. Mutant complementation with pDA-17:BTH_I1704 was able to restore anaerobic growth on nitrate, nitrate reductase activity and biofilm formation, but did not restore motility. This study highlights the potential importance of molybdoenzyme-dependent anaerobic respiration in the survival and virulence of B. thailandensis.

  4. SUSCEPTIBILITY AND PROTECTIVE MECHANISMS OF MOTILE AND NON MOTILE CELLS OF HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE) TO PHOTOOXIDATIVE STRESS(1).

    PubMed

    Han, Danxiang; Wang, Junfeng; Sommerfeld, Milton; Hu, Qiang

    2012-06-01

    The life cycle of the unicellular green alga Haematococcus pluvialis consists of motile and nonmotile stages under typical growing conditions. In this study, we observed that motile cells were more susceptible than nonmotile cells to high light, resulting in a decrease in population density and photo-bleaching. Using two Haematococcus strains, CCAP 34/12 (a motile cell dominated strain) and SAG 34/1b (a nonmotile cell dominated strain), as model systems we investigated the cause of cell death and the protective mechanisms of the cells that survived high light. The death of motile cells under high light was attributed to the generation of excess reactive oxygen species (ROS), which caused severe damage to the photosynthetic components and the membrane system. Motile cells were able to dissipate excess light energy by nonphotochemical quenching and to relax ROS production by a partially up-regulated scavenging enzyme system. However, these strategies were not sufficient to protect the motile cells from high light stress. In contrast, nonmotile cells were able to cope with and survive under high light by (i) relaxing the over-reduced photosynthetic electron transport chain (PETC), thereby effectively utilizing PETC-generated NADPH to produce storage starch, neutral lipid, and astaxanthin, and thus preventing formation of excess ROS; (ii) down-regulating the linear electron transport by decreasing the level of cytochrome f; and (iii) consuming excess electrons produced by PSII via a significantly enhanced plastid terminal oxidase pathway.

  5. Transport, motility, biofilm forming potential and survival of Bacillus subtilis exposed to cold temperature and freeze-thaw.

    PubMed

    Asadishad, Bahareh; Olsson, Adam L J; Dusane, Devendra H; Ghoshal, Subhasis; Tufenkji, Nathalie

    2014-07-01

    In cold climate regions, microorganisms in upper layers of soil are subject to low temperatures and repeated freeze-thaw (FT) conditions during the winter. We studied the effects of cold temperature and FT cycles on the viability and survival strategies (namely motility and biofilm formation) of the common soil bacterium and model pathogen Bacillus subtilis. We also examined the effect of FT on the transport behavior of B. subtilis at two solution ionic strengths (IS: 10 and 100 mM) in quartz sand packed columns. Finally, to study the mechanical properties of the bacteria-surface bond, a quartz crystal microbalance with dissipation monitoring (QCM-D) was used to monitor changes in bond stiffness when B. subtilis attached to a quartz substrate (model sand surface) under different environmental conditions. We observed that increasing the number of FT cycles decreased bacterial viability and that B. subtilis survived for longer time periods in higher IS solution. FT treatment decreased bacterial swimming motility and the transcription of flagellin encoding genes. Although FT exposure had no significant effect on the bacterial growth rate, it substantially decreased B. subtilis biofilm formation and correspondingly decreased the transcription of matrix production genes in higher IS solution. As demonstrated with QCM-D, the bond stiffness between B. subtilis and the quartz surface decreased after FT. Moreover, column transport studies showed higher bacterial retention onto sand grains after exposure to FT. This investigation demonstrates how temperature variations around the freezing point in upper layers of soil can influence key bacterial properties and behavior, including survival and subsequent transport.

  6. Repression of flagella motility in enterohemorrhagic Escherichia coli O157:H7 by mucin components.

    PubMed

    Kim, Jong Chul; Yoon, Jang W; Kim, Cheorl-Ho; Park, Mi-Sun; Cho, Seung-Hak

    2012-07-13

    Whole genome-scale transcriptome analysis of enterohemorrhagic Escherichia coli (EHEC) O157:H7 EDL933 was performed to investigate the influence of mucin components on the EHEC gene expression. Here we report that the 732 candidate genes were differentially expressed by the presence of 0.5% porcine stomach mucin, including the 8 flagella-related genes. Quantitative real-time PCR analyses revealed that the transcription expression of the flg genes (encoding the structural components for flagella basal body) was down-regulated by the mucin components. Indeed, bacterial swarming motility was drastically reduced when grown on 0.3% trypton agar plates containing the mucin. These results imply that gastrointestinal (GI) mucin is a possible environmental signal which negatively regulates the flagellation of EHEC O157:H7 in the GI tract.

  7. A semi-stochastic cell-based model for in vitro infected 'wound' healing through motility reduction: a simulation study.

    PubMed

    Vermolen, F J; Gefen, A

    2013-02-07

    We consider the migration and viability of individual cells in bacterial-infected cell colonies. Cell movement is assumed to take place as a result of sensing the strain energy density as a mechanical stimulus. The model is based on tracking the motion and viability of each individual cell in a cell colony, and the formalism was published in an earlier paper. The present innovations are an application to a simulation of a 'wound healing assay' in which bacteria infect the wound through impairing the motility of cells and an extension with effects from inertia. Though based on simple principles, the model is based on experiments on living fibroblasts on a flat substrate.

  8. New insights into the function of a versatile class of membrane molecular motors from studies of Myxococcus xanthus surface (gliding) motility.

    PubMed

    Mignot, Tâm; Nöllmann, Marcelo

    2017-03-02

    Cell motility is a central function of living cells, as it empowers colonization of new environmental niches, cooperation, and development of multicellular organisms. This process is achieved by complex yet precise energy-consuming machineries in both eukaryotes and bacteria. Bacteria move on surfaces using extracellular appendages such as flagella and pili but also by a less-understood process called gliding motility. During this process, rod-shaped bacteria move smoothly along their long axis without any visible morphological changes besides occasional bending. For this reason, the molecular mechanism of gliding motility and its origin have long remained a complete mystery. An important breakthrough in the understanding of gliding motility came from single cell and genetic studies in the delta-proteobacterium Myxococcus xanthus. These early studies revealed, for the first time, the existence of bacterial Focal Adhesion complexes (FA). FAs are formed at the bacterial pole and rapidly move towards the opposite cell pole. Their attachment to the underlying surface is linked to cell propulsion, in a process similar to the rearward translocation of actomyosin complexes in Apicomplexans. The protein machinery that forms at FAs was shown to contain up to seventeen proteins predicted to localize in all layers of the bacterial cell envelope, the cytosolic face, the inner membrane (IM), the periplasmic space and the outer membrane (OM). Among these proteins, a proton-gated channel at the inner membrane was identified as the molecular motor. Thus, thrust generation requires the transduction of traction forces generated at the inner membrane through the cell envelope beyond the rigid barrier of the bacterial peptidoglycan.

  9. New insights into the function of a versatile class of membrane molecular motors from studies of Myxococcus xanthus surface (gliding) motility

    PubMed Central

    Mignot, Tâm; Nöllmann, Marcelo

    2017-01-01

    Cell motility is a central function of living cells, as it empowers colonization of new environmental niches, cooperation, and development of multicellular organisms. This process is achieved by complex yet precise energy-consuming machineries in both eukaryotes and bacteria. Bacteria move on surfaces using extracellular appendages such as flagella and pili but also by a less-understood process called gliding motility. During this process, rod-shaped bacteria move smoothly along their long axis without any visible morphological changes besides occasional bending. For this reason, the molecular mechanism of gliding motility and its origin have long remained a complete mystery. An important breakthrough in the understanding of gliding motility came from single cell and genetic studies in the delta-proteobacterium Myxococcus xanthus. These early studies revealed, for the first time, the existence of bacterial Focal Adhesion complexes (FA). FAs are formed at the bacterial pole and rapidly move towards the opposite cell pole. Their attachment to the underlying surface is linked to cell propulsion, in a process similar to the rearward translocation of actomyosin complexes in Apicomplexans. The protein machinery that forms at FAs was shown to contain up to seventeen proteins predicted to localize in all layers of the bacterial cell envelope, the cytosolic face, the inner membrane (IM), the periplasmic space and the outer membrane (OM). Among these proteins, a proton-gated channel at the inner membrane was identified as the molecular motor. Thus, thrust generation requires the transduction of traction forces generated at the inner membrane through the cell envelope beyond the rigid barrier of the bacterial peptidoglycan. PMID:28357395

  10. Optimization of a validated stability-indicating RP-LC method for the determination of fulvestrant from polymeric based nanoparticle systems, drugs and biological samples.

    PubMed

    Gumustas, Mehmet; Sengel-Turk, Ceyda Tuba; Hascicek, Canan; Ozkan, Sibel A

    2014-10-01

    Fulvestrant is used for the treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression following anti-estrogen therapy. Several reversed-phase columns with variable silica materials, diameters, lengths, etc., were tested for the optimization study. A good chromatographic separation was achieved using a Waters X-Terra RP(18) column (250 × 4.6 mm i.d. × 5 µm) and a mobile phase, consisting of a mixture of acetonitrile-water (65:35; v/v) containing phosphoric acid (0.1%). The separation was carried out 40 °C with detection at 215 nm.The calibration curves were linear over the concentration range between 1.0-300 and 1.0-200 µg/mL for standard solutions and biological media, respectively. The proposed method is accurate and reproducible. Forced degradation studies were also realized. This fully validated method allows the direct determination of fulvestrant in dosage form and biological samples. The average recovery of the added fulvestrant amount in the samples was between 98.22 and 104.03%. The proposed method was also applied for the determination of fulvestrant from the polymeric-based nanoparticle systems. No interference from using polymers and other excipients was observed in in vitro drug release studies. Therefore an incorporation efficiency of fulvestrant-loaded nanoparticle could be determined accurately and specifically.

  11. Computational and Modeling Strategies for Cell Motility

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Yang, Xiaofeng; Adalsteinsson, David; Elston, Timothy C.; Jacobson, Ken; Kapustina, Maryna; Forest, M. Gregory

    A predictive simulation of the dynamics of a living cell remains a fundamental modeling and computational challenge. The challenge does not even make sense unless one specifies the level of detail and the phenomena of interest, whether the focus is on near-equilibrium or strongly nonequilibrium behavior, and on localized, subcellular, or global cell behavior. Therefore, choices have to be made clear at the outset, ranging from distinguishing between prokaryotic and eukaryotic cells, specificity within each of these types, whether the cell is "normal," whether one wants to model mitosis, blebs, migration, division, deformation due to confined flow as with red blood cells, and the level of microscopic detail for any of these processes. The review article by Hoffman and Crocker [48] is both an excellent overview of cell mechanics and an inspiration for our approach. One might be interested, for example, in duplicating the intricate experimental details reported in [43]: "actin polymerization periodically builds a mechanical link, the lamellipodium, connecting myosin motors with the initiation of adhesion sites, suggesting that the major functions driving motility are coordinated by a biomechanical process," or to duplicate experimental evidence of traveling waves in cells recovering from actin depolymerization [42, 35]. Modeling studies of lamellipodial structure, protrusion, and retraction behavior range from early mechanistic models [84] to more recent deterministic [112, 97] and stochastic [51] approaches with significant biochemical and structural detail. Recent microscopic-macroscopic models and algorithms for cell blebbing have been developed by Young and Mitran [116], which update cytoskeletal microstructure via statistical sampling techniques together with fluid variables. Alternatively, whole cell compartment models (without spatial details) of oscillations in spreading cells have been proposed [35, 92, 109] which show positive and negative feedback

  12. Self-Starting Micromotors in a Bacterial Bath

    NASA Astrophysics Data System (ADS)

    Angelani, Luca; di Leonardo, Roberto; Ruocco, Giancarlo

    2009-01-01

    Micromotors pushed by biological entities, such as motile bacteria, constitute a fascinating way to convert chemical energy into mechanical work at the micrometer scale. Here we show, by using numerical simulations, that a properly designed asymmetric object can be spontaneously set into the desired motion when immersed in a chaotic bacterial bath. Our findings open the way to conceive new hybrid microdevices exploiting the mechanical power production of bacterial organisms. Moreover, the system provides an example of how, in contrast with equilibrium thermal baths, the irreversible chaotic motion of active particles can be rectified by asymmetric environments.

  13. Scale-Invariant Correlations in Dynamic Bacterial Clusters

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Dong, Xu; Be'er, Avraham; Swinney, Harry L.; Zhang, H. P.

    2012-04-01

    In Bacillus subtilis colonies, motile bacteria move collectively, spontaneously forming dynamic clusters. These bacterial clusters share similarities with other systems exhibiting polarized collective motion, such as bird flocks or fish schools. Here we study experimentally how velocity and orientation fluctuations within clusters are spatially correlated. For a range of cell density and cluster size, the correlation length is shown to be 30% of the spatial size of clusters, and the correlation functions collapse onto a master curve after rescaling the separation with correlation length. Our results demonstrate that correlations of velocity and orientation fluctuations are scale invariant in dynamic bacterial clusters.

  14. Calcium-Enhanced Twitching Motility in Xylella fastidiosa Is Linked to a Single PilY1 Homolog

    PubMed Central

    Cruz, Luisa F.; Parker, Jennifer K.; Cobine, Paul A.

    2014-01-01

    The plant-pathogenic bacterium Xylella fastidiosa is restricted to the xylem vessel environment, where mineral nutrients are transported through the plant host; therefore, changes in the concentrations of these elements likely impact the growth and virulence of this bacterium. Twitching motility, dependent on type IV pili (TFP), is required for movement against the transpiration stream that results in basipetal colonization. We previously demonstrated that calcium (Ca) increases the motility of X. fastidiosa, although the mechanism was unknown. PilY1 is a TFP structural protein recently shown to bind Ca and to regulate twitching and adhesion in bacterial pathogens of humans. Sequence analysis identified three pilY1 homologs in X. fastidiosa (PD0023, PD0502, and PD1611), one of which (PD1611) contains a Ca-binding motif. Separate deletions of PD0023 and PD1611 resulted in mutants that still showed twitching motility and were not impaired in attachment or biofilm formation. However, the response of increased twitching at higher Ca concentrations was lost in the pilY1-1611 mutant. Ca does not modulate the expression of any of the X. fastidiosa PilY1 homologs, although it increases the expression of the retraction ATPase pilT during active movement. The evidence presented here suggests functional differences between the PilY1 homologs, which may provide X. fastidiosa with an adaptive advantage in environments with high Ca concentrations, such as xylem sap. PMID:25217013

  15. Calcium-Enhanced Twitching Motility in Xylella fastidiosa Is Linked to a Single PilY1 Homolog.

    PubMed

    Cruz, Luisa F; Parker, Jennifer K; Cobine, Paul A; De La Fuente, Leonardo

    2014-12-01

    The plant-pathogenic bacterium Xylella fastidiosa is restricted to the xylem vessel environment, where mineral nutrients are transported through the plant host; therefore, changes in the concentrations of these elements likely impact the growth and virulence of this bacterium. Twitching motility, dependent on type IV pili (TFP), is required for movement against the transpiration stream that results in basipetal colonization. We previously demonstrated that calcium (Ca) increases the motility of X. fastidiosa, although the mechanism was unknown. PilY1 is a TFP structural protein recently shown to bind Ca and to regulate twitching and adhesion in bacterial pathogens of humans. Sequence analysis identified three pilY1 homologs in X. fastidiosa (PD0023, PD0502, and PD1611), one of which (PD1611) contains a Ca-binding motif. Separate deletions of PD0023 and PD1611 resulted in mutants that still showed twitching motility and were not impaired in attachment or biofilm formation. However, the response of increased twitching at higher Ca concentrations was lost in the pilY1-1611 mutant. Ca does not modulate the expression of any of the X. fastidiosa PilY1 homologs, although it increases the expression of the retraction ATPase pilT during active movement. The evidence presented here suggests functional differences between the PilY1 homologs, which may provide X. fastidiosa with an adaptive advantage in environments with high Ca concentrations, such as xylem sap.

  16. Dynamic complex formation between HD-GYP, GGDEF and PilZ domain proteins regulates motility in Xanthomonas campestris.

    PubMed

    Ryan, Robert P; McCarthy, Yvonne; Kiely, Patrick A; O'Connor, Rosemary; Farah, Chuck S; Armitage, Judith P; Dow, J Maxwell

    2012-11-01

    RpfG is a member of a class of wide spread bacterial two-component regulators with an HD-GYP cyclic di-GMP phosphodiesterase domain. In the plant pathogen Xanthomonas campestris, RpfG together with the sensor kinase RpfC regulates multiple factors as a response to the cell-to-cell Diffusible Signalling Factor (DSF). A dynamic physical interaction of RpfG with two diguanylate cyclase (GGDEF) domain proteins controls motility. Here we show that, contrary to expectation, regulation of motility by the GGDEF domain proteins does not depend upon their cyclic di-GMP synthetic activity. Furthermore we show that the complex of RpfG and GGDEF domain proteins recruits a specific PilZ domain 'adaptor' protein, and this complex then interacts with the pilus motor proteins PilU and PiIT. The results support a model in which DSF signalling influences motility through the highly regulated dynamic interaction of proteins that affect pilus action. A specific motif that we identify to be required for HD-GYP domain interaction is conserved in a number of GGDEF domain proteins, suggesting that regulation via interdomain interactions is of broad relevance.

  17. Geometry-Driven Polarity in Motile Amoeboid Cells.

    PubMed

    Nagel, Oliver; Guven, Can; Theves, Matthias; Driscoll, Meghan; Losert, Wolfgang; Beta, Carsten

    2014-01-01

    Motile eukaryotic cells, such as leukocytes, cancer cells, and amoeba, typically move inside the narrow interstitial spacings of tissue or soil. While most of our knowledge of actin-driven eukaryotic motility was obtained from cells that move on planar open surfaces, recent work has demonstrated that confinement can lead to strongly altered motile behavior. Here, we report experimental evidence that motile amoeboid cells undergo a spontaneous symmetry breaking in confined interstitial spaces. Inside narrow channels, the cells switch to a highly persistent, unidirectional mode of motion, moving at a constant speed along the channel. They remain in contact with the two opposing channel side walls and alternate protrusions of their leading edge near each wall. Their actin cytoskeleton exhibits a characteristic arrangement that is dominated by dense, stationary actin foci at the side walls, in conjunction with less dense dynamic regions at the leading edge. Our experimental findings can be explained based on an excitable network model that accounts for the confinement-induced symmetry breaking and correctly recovers the spatio-temporal pattern of protrusions at the leading edge. Since motile cells typically live in the narrow interstitial spacings of tissue or soil, we expect that the geometry-driven polarity we report here plays an important role for movement of cells in their natural environment.

  18. Neuropeptide Y inhibits interleukin-1 beta-induced microglia motility.

    PubMed

    Ferreira, Raquel; Santos, Tiago; Cortes, Luísa; Cochaud, Stéphanie; Agasse, Fabienne; Silva, Ana Paula; Xapelli, Sara; Malva, João O

    2012-01-01

    Increasing evidences suggest that neuropeptide Y (NPY) may act as a key modulator of the cross-talk between the brain and the immune system in health and disease. In the present study, we dissected the possible inhibitory role of NPY upon inflammation-associated microglial cell motility. NPY, through activation of Y(1) receptors, was found to inhibit lipopolysaccharide (LPS)-induced microglia (N9 cell line) motility. Moreover, stimulation of microglia with LPS was inhibited by IL-1 receptor antagonist (IL-1ra), suggesting the involvement of endogenous interleukin-1 beta (IL-1β) in this process. Direct stimulation with IL-1β promoted downstream p38 mitogen-activated protein kinase mobilization and increased microglia motility. Moreover, consistently, p38 mitogen-activated protein kinase inhibition decreased the extent of actin filament reorganization occurring during plasma membrane ruffling and p38 phosphorylation was inhibited by NPY, involving Y(1) receptors. Significantly, the key inhibitory role of NPY on LPS-induced motility of CD11b-positive cells was further confirmed in mouse brain cortex explants. In summary, we revealed a novel functional role for NPY in the regulation of microglial function that may have important implications in the modulation of CNS injuries/diseases where microglia migration/motility might play a role.

  19. PACRG, a protein linked to ciliary motility, mediates cellular signaling.

    PubMed

    Loucks, Catrina M; Bialas, Nathan J; Dekkers, Martijn P J; Walker, Denise S; Grundy, Laura J; Li, Chunmei; Inglis, P Nick; Kida, Katarzyna; Schafer, William R; Blacque, Oliver E; Jansen, Gert; Leroux, Michel R

    2016-07-01

    Cilia are microtubule-based organelles that project from nearly all mammalian cell types. Motile cilia generate fluid flow, whereas nonmotile (primary) cilia are required for sensory physiology and modulate various signal transduction pathways. Here we investigate the nonmotile ciliary signaling roles of parkin coregulated gene (PACRG), a protein linked to ciliary motility. PACRG is associated with the protofilament ribbon, a structure believed to dictate the regular arrangement of motility-associated ciliary components. Roles for protofilament ribbon-associated proteins in nonmotile cilia and cellular signaling have not been investigated. We show that PACRG localizes to a small subset of nonmotile cilia in Caenorhabditis elegans, suggesting an evolutionary adaptation for mediating specific sensory/signaling functions. We find that it influences a learning behavior known as gustatory plasticity, in which it is functionally coupled to heterotrimeric G-protein signaling. We also demonstrate that PACRG promotes longevity in C. elegans by acting upstream of the lifespan-promoting FOXO transcription factor DAF-16 and likely upstream of insulin/IGF signaling. Our findings establish previously unrecognized sensory/signaling functions for PACRG and point to a role for this protein in promoting longevity. Furthermore, our work suggests additional ciliary motility-signaling connections, since EFHC1 (EF-hand containing 1), a potential PACRG interaction partner similarly associated with the protofilament ribbon and ciliary motility, also positively regulates lifespan.

  20. PACRG, a protein linked to ciliary motility, mediates cellular signaling

    PubMed Central

    Loucks, Catrina M.; Bialas, Nathan J.; Dekkers, Martijn P. J.; Walker, Denise S.; Grundy, Laura J.; Li, Chunmei; Inglis, P. Nick; Kida, Katarzyna; Schafer, William R.; Blacque, Oliver E.; Jansen, Gert; Leroux, Michel R.

    2016-01-01

    Cilia are microtubule-based organelles that project from nearly all mammalian cell types. Motile cilia generate fluid flow, whereas nonmotile (primary) cilia are required for sensory physiology and modulate various signal transduction pathways. Here we investigate the nonmotile ciliary signaling roles of parkin coregulated gene (PACRG), a protein linked to ciliary motility. PACRG is associated with the protofilament ribbon, a structure believed to dictate the regular arrangement of motility-associated ciliary components. Roles for protofilament ribbon–associated proteins in nonmotile cilia and cellular signaling have not been investigated. We show that PACRG localizes to a small subset of nonmotile cilia in Caenorhabditis elegans, suggesting an evolutionary adaptation for mediating specific sensory/signaling functions. We find that it influences a learning behavior known as gustatory plasticity, in which it is functionally coupled to heterotrimeric G-protein signaling. We also demonstrate that PACRG promotes longevity in C. elegans by acting upstream of the lifespan-promoting FOXO transcription factor DAF-16 and likely upstream of insulin/IGF signaling. Our findings establish previously unrecognized sensory/signaling functions for PACRG and point to a role for this protein in promoting longevity. Furthermore, our work suggests additional ciliary motility-signaling connections, since EFHC1 (EF-hand containing 1), a potential PACRG interaction partner similarly associated with the protofilament ribbon and ciliary motility, also positively regulates lifespan. PMID:27193298

  1. Sodium affects the sperm motility in the European eel.

    PubMed

    Vílchez, M Carmen; Morini, Marina; Peñaranda, David S; Gallego, Víctor; Asturiano, Juan F; Pérez, Luz

    2016-08-01

    The role of seminal plasma sodium and activation media sodium on sperm motility was examined by selectively removing the element from these two media, in European eel sperm. Sperm size (sperm head area) was also measured using an ASMA (Automated Sperm Morphometry Analyses) system, in the different conditions. Intracellular sodium [Na(+)]i was quantitatively analyzed by first time in the spermatozoa from a marine fish species. Measurement of [Na(+)]i was done before and after motility activation, by Flow Cytometry, using CoroNa Green AM as a dye. Sperm motility activation induced an increase in [Na(+)]i, from 96.72mM in quiescent stage to 152.21mM post-activation in seawater. A significant decrease in sperm head area was observed post-activation in seawater. There was a notable reduction in sperm motility when sodium was removed from the seminal plasma, but not when it was removed from the activation media. Sodium removal was also linked to a significant reduction in sperm head area in comparison to the controls. Our results indicate that the presence of the ion Na(+) in the seminal plasma (or in the extender medium) is necessary for the preservation of sperm motility in European eel, probably because it plays a role in maintaining an appropriate sperm cell volume in the quiescent stage of the spermatozoa.

  2. Bidirectional motility of the fission yeast kinesin-5, Cut7

    SciTech Connect

    Edamatsu, Masaki

    2014-03-28

    Highlights: • Motile properties of Cut7 (fission yeast kinesin-5) were studied for the first time. • Half-length Cut7 moved toward plus-end direction of microtubule. • Full-length Cut7 moved toward minus-end direction of microtubule. • N- and C-terminal microtubule binding sites did not switch the motile direction. - Abstract: Kinesin-5 is a homotetrameric motor with its motor domain at the N-terminus. Kinesin-5 crosslinks microtubules and functions in separating spindle poles during mitosis. In this study, the motile properties of Cut7, fission yeast kinesin-5, were examined for the first time. In in vitro motility assays, full-length Cut7 moved toward minus-end of microtubules, but the N-terminal half of Cut7 moved toward the opposite direction. Furthermore, additional truncated constructs lacking the N-terminal or C-terminal regions, but still contained the motor domain, did not switch the motile direction. These indicated that Cut7 was a bidirectional motor, and microtubule binding regions at the N-terminus and C-terminus were not involved in its directionality.

  3. 3D timelapse analysis of muscle satellite cell motility.

    PubMed

    Siegel, Ashley L; Atchison, Kevin; Fisher, Kevin E; Davis, George E; Cornelison, D D W

    2009-10-01

    Skeletal muscle repair and regeneration requires the activity of satellite cells, a population of myogenic stem cells scattered throughout the tissue and activated to proliferate and differentiate in response to myotrauma or disease. While it seems likely that satellite cells would need to navigate local muscle tissue to reach damaged areas, relatively little data on such motility exist, and most studies have been with immortalized cell lines. We find that primary satellite cells are significantly more motile than myoblast cell lines, and that adhesion to laminin promotes primary cell motility more than fourfold over other substrates. Using timelapse videomicroscopy to assess satellite cell motility on single living myofibers, we have identified a requirement for the laminin-binding integrin alpha 7 beta 1 in satellite cell motility, as well as a role for hepatocyte growth factor in promoting directional persistence. The extensive migratory behavior of satellite cells resident on muscle fibers suggests caution when determining, based on fixed specimens, whether adjacent cells are daughters from the same mother cell. We also observed more persistent long-term contact between individual satellite cells than has been previously supposed, potential cell-cell attractive and repulsive interactions, and migration between host myofibers. Based on such activity, we assayed for expression of "pathfinding" cues, and found that satellite cells express multiple guidance ligands and receptors. Together, these data suggest that satellite cell migration in vivo may be more extensive than currently thought, and could be regulated by combinations of signals, including adhesive haptotaxis, soluble factors, and guidance cues.

  4. MglC, a Paralog of Myxococcus xanthus GTPase-Activating Protein MglB, Plays a Divergent Role in Motility Regulation

    PubMed Central

    McLoon, Anna L.; Wuichet, Kristin; Häsler, Michael; Keilberg, Daniela; Szadkowski, Dobromir

    2015-01-01

    predation of other bacterial species and formation of multicellular, spore-filled fruiting bodies. One feature of the large M. xanthus genome is that it contains many gene duplications. Here, we compare the products of one example of gene duplication and divergence, in which a paralog of the cognate MglA GTPase-activating protein MglB has acquired a different and opposing role in the regulation of cellular polarity and motility, processes critical to the bacterium's social behaviors. PMID:26574508

  5. Motility of Helicobacter pylori Is Coordinately Regulated by the Transcriptional Activator FlgR, an NtrC Homolog

    PubMed Central

    Spohn, Gunther; Scarlato, Vincenzo

    1999-01-01

    ς54 is the subunit of bacterial RNA polymerase that transcribes from promoters with enhancer elements bound by enhancer-binding proteins. By computer searches of Helicobacter pylori genomic sequences, chromosomal gene disruption, and RNA analyses, we have identified ς54-recognized promoters that regulate transcription of flagellar basal body and hook genes, as well as the enhancer-binding protein FlgR (flagellum regulator), a transactivating protein of the NtrC family. We demonstrate that FlgR is required for bacterial motility and transcription of five promoters for seven basal body and hook genes. In addition, FlgR acts as a repressor of transcription of the ς28-regulated flaA flagellin gene promoter, while changes in DNA topology repress transcription of the ς54-regulated flaB flagellin gene promoter. Our data indicate that regulation of flagellar gene expression in H. pylori shows similarities with that in enterobacteriaceae and Caulobacter. PMID:9882675

  6. Bacteria rolling: motilities of rosette colonies in Caulobacter crescentus

    NASA Astrophysics Data System (ADS)

    Zeng, Yu; Liu, Bin

    2016-11-01

    The aquatic bacterium Caulobacter crescentus has two life cycle stages with distinct motilities: freely swimming swarmer cells and immotile stalked cells. Here, we show a new type of movement performed by freely suspended rosettes, spontaneous aggregates of stalked cells aligned radially relative to each other. Reproductive rosette members generate predivisional daughter cells with flagella, inducing rotations of the rosette as a whole. Such rotations exhibit dynamic angular velocities and lead to intermittent linear movements along liquid-solid interfaces, resembling rolling movements. We reconstructed the translational and rotational dynamics of the rosette movements from high-speed filming and long-term tracking. A mechanical model was developed to explain the hydrodynamic mechanism underlying such motilities. Our study illustrated a nontrivial mechanism for clustered bacteria to achieve motilities and sheds light on the adaptive significance of the collective behaviors of microorganisms in complex fluid environments.

  7. Highly sensitive kinesin-microtubule motility assays using SLIM

    NASA Astrophysics Data System (ADS)

    Kandel, Mikhail; Teng, Kai Wen; Selvin, Paul R.; Popescu, Gabriel

    2016-03-01

    We provide an experimental demonstration of Spatial Light Interference Microscopy (SLIM) as a tool for measuring the motion of 25 nm tubulin structures without the use of florescence labels. Compared to intensity imaging methods such as phase contrast or DIC, our imaging technique relies on the ratios of images associated with optically introduced phase shifts, thus implicitly removing background illumination. To demonstrate our new found capabilities, we characterize kinesin-based motility continuously over periods of time where fluorescence would typically photobleach. We exploit this new method to compare the motility of microtubules at low ATP concentrations, with and without the tagging proteins formerly required to perform these studies. Our preliminary results show that the tags have a non-negligible effect on the microtubule motility, slowing the process down by more than 10%.

  8. Symbolic dynamics of jejunal motility in the irritable bowel

    NASA Astrophysics Data System (ADS)

    Wackerbauer, Renate; Schmidt, Thomas

    1999-09-01

    Different studies of the irritable bowel syndrome (IBS) by conventional analysis of jejunal motility report conflicting results. Therefore, our aim is to quantify the jejunal contraction activity by symbolic dynamics in order to discriminate between IBS and control subjects. Contraction amplitudes during fasting motility (phase II) are analyzed for 30 IBS and 30 healthy subjects. On the basis of a particular scale-independent discretization of the contraction amplitudes with respect to the median, IBS patients are characterized by increased block entropy as well as increased mean contraction amplitude. In a further more elementary level of analysis these differences can be reduced to specific contraction patterns within the time series, namely the fact that successive large contraction amplitudes are less ordered in IBS than in controls. These significant differences in jejunal motility may point to an altered control of the gut in IBS, although further studies on a representative number of patients have to be done for a validation of these findings.

  9. Autocrine motility factor modulates EGF-mediated invasion signaling

    PubMed Central

    Kho, Dhong Hyo; Zhang, Tianpeng; Balan, Vitaly; Yi, Wang; Ha, Seung-Wook; Xie, Youming; Raz, Avraham

    2014-01-01

    Autocrine motility factor (AMF) enhances invasion by breast cancer cells, but how its secretion and effector signaling are controlled in the tumor microenvironment is not fully understood. In this study, we investigated these issues with a chimeric AMF that is secreted at high levels through a canonical ER/Golgi pathway. Using this tool, we found that AMF enhances tumor cell motility by activating AKT/ERK, altering actin organization and stimulating β-catenin/TCF and AP-1 transcription. EGF enhanced secretion of AMF through its casein kinase 2-mediated phosphorylation. RNAi-mediated attenuation of AMF expression inhibited EGF-induced invasion by suppressing ERK signaling. Conversely, exogenous AMF overcame the inhibitory effect of EGFR inhibitor gefitinib on invasive motility by activating HER2 signaling. Taken together, our findings show how AMF modulates EGF-induced invasion while affecting acquired resistance to cytotoxic drugs in the tumor microenvironment. PMID:24576828

  10. TUTORIAL: An introduction to cell motility for the physical scientist

    NASA Astrophysics Data System (ADS)

    Fletcher, Daniel A.; Theriot, Julie A.

    2004-03-01

    Directed, purposeful movement is one of the qualities that we most closely associate with living organisms, and essentially all known forms of life on this planet exhibit some type of self-generated movement or motility. Even organisms that remain sessile most of the time, like flowering plants and trees, are quite busy at the cellular level, with large organelles, including chloroplasts, constantly racing around within cellular boundaries. Directed biological movement requires that the cell be able to convert its abundant stores of chemical energy into mechanical energy. Understanding how this mechanochemical energy transduction takes place and understanding how small biological forces generated at the molecular level are marshaled and organized for large-scale cellular or organismal movements are the focus of the field of cell motility. This tutorial, aimed at readers with a background in physical sciences, surveys the state of current knowledge and recent advances in modeling cell motility.

  11. Primary esophageal motility disorders (concise review for clinicians).

    PubMed

    Simić, A; Raznatović, Z; Skrobić, O; Pesko, P

    2006-01-01

    Primary esophageal motility disorders comprise various abnormal manometric patterns which usually present with dysphagia or chest pain. Some, such as achalasia, are diseases with a well defined pathology, characteristic manometric features, and good response to treatments directed towards the palliation of symptoms. Other disorders, such as diffuse esophageal spasm and nutcracker esophagus, have no well defined pathology and could represent a range of motility abnormalities associated with subtle neuropathic changes, gastresophageal reflux and anxiety states. On the other hand, hypocontracting esophagus is generally caused by weak musculature commonly associated with gastresophageal reflux disease. Although manometric patterns have been defined for these disorders, the relation with symptoms is poorly defined and in some cases the response to medical or surgical therapy unpredictable. The aim of this paper is to present a wide spectrum of the primary esophageal motility disorders, as well as to give a concise review for the clinicians encountering these specific diseases.

  12. Bacterial vaginosis.

    PubMed Central

    Spiegel, C A

    1991-01-01

    Bacterial vaginosis (BV) is the most common of the vaginitides affecting women of reproductive age. It appears to be due to an alteration in the vaginal ecology by which Lactobacillus spp., the predominant organisms in the healthy vagina, are replaced by a mixed flora including Prevotella bivia, Prevotella disiens, Porphyromonas spp., Mobiluncus spp., and Peptostreptococcus spp. All of these organisms except Mobiluncus spp. are also members of the endogenous vaginal flora. While evidence from treatment trials does not support the notion that BV is sexually transmitted, recent studies have shown an increased risk associated with multiple sexual partners. It has also been suggested that the pathogenesis of BV may be similar to that of urinary tract infections, with the rectum serving as a reservoir for some BV-associated flora. The organisms associated with BV have also been recognized as agents of female upper genital tract infection, including pelvic inflammatory disease, and the syndrome BV has been associated with adverse outcome of pregnancy, including premature rupture of membranes, chorioamnionitis, and fetal loss; postpartum endometritis; cuff cellulitis; and urinary tract infections. The mechanisms by which the BV-associated flora causes the signs of BV are not well understood, but a role for H2O2-producing Lactobacillus spp. in protecting against colonization by catalase-negative anaerobic bacteria has been recognized. These and other aspects of BV are reviewed. PMID:1747864

  13. Unidirecetional motility of excherichia coli in restrictive capillaries

    SciTech Connect

    Liu, Z.; Papadopoulos, K.D.

    1995-10-01

    In a 6-{mu}m capillary filled with buffer and in the absence of any chemotactic stimuli, Escherichia coli K-12 cells swim persistently in only one direction. This behavior of E. coli can be simply explained by means of the length and relative rigidity of their flagella. Single-cell motility parameters-swimming speed, turn angle, and run length time-were measured. Compared with the motility parameters measured in bulk phase, turn angle was influenced because of the effect of the geometrical restriction. 30 refs., 6 figs.

  14. Polymorphonuclear leucocyte motility in men with ankylosing spondylitis.

    PubMed Central

    Pease, C T; Fennell, M; Brewerton, D A

    1989-01-01

    The polymorphonuclear leucocyte (PMN) response to a chemotactic or chemokinetic stimulus is enhanced in men with ankylosing spondylitis (AS). This effect does not parallel the severity of disease activity or the size of the acute phase response, and it is independent of non-steroidal anti-inflammatory drug treatment. Polymorph function is normal in HLA-B27 positive brothers of probands with AS and in other HLA-B27 positive individuals in the absence of disease. Polymorph motility is also normal in patients with psoriasis vulgaris or Crohn's disease, indicating that enhanced PMN motility is not a non-specific consequence of all inflammatory disorders. PMID:2784306

  15. Enhanced motility of a microswimmer in rigid and elastic confinement.

    PubMed

    Ledesma-Aguilar, Rodrigo; Yeomans, Julia M

    2013-09-27

    We analyze the effect of confining rigid and elastic boundaries on the motility of a model dipolar microswimmer. Flexible boundaries are deformed by the velocity field of the swimmer in such a way that the motility of both extensile and contractile swimmers is enhanced. The magnitude of the increase in swimming velocity is controlled by the ratio of the swimmer-advection and elastic time scales, and the dipole moment of the swimmer. We explain our results by considering swimming between inclined rigid boundaries.

  16. Enhanced Motility of a Microswimmer in Rigid and Elastic Confinement

    NASA Astrophysics Data System (ADS)

    Ledesma-Aguilar, Rodrigo; Yeomans, Julia M.

    2013-09-01

    We analyze the effect of confining rigid and elastic boundaries on the motility of a model dipolar microswimmer. Flexible boundaries are deformed by the velocity field of the swimmer in such a way that the motility of both extensile and contractile swimmers is enhanced. The magnitude of the increase in swimming velocity is controlled by the ratio of the swimmer-advection and elastic time scales, and the dipole moment of the swimmer. We explain our results by considering swimming between inclined rigid boundaries.

  17. Small bowel bacterial overgrowth

    MedlinePlus

    Overgrowth - intestinal bacteria; Bacterial overgrowth - intestine; Small intestinal bacterial overgrowth; SIBO ... intestine does not have a high number of bacteria. Excess bacteria in the small intestine may use ...

  18. BolA Is a Transcriptional Switch That Turns Off Motility and Turns On Biofilm Development

    PubMed Central

    Dressaire, Clémentine; Moreira, Ricardo Neves; Barahona, Susana; Alves de Matos, António Pedro

    2015-01-01

    ABSTRACT Bacteria are extremely versatile organisms that rapidly adapt to changing environments. When bacterial cells switch from planktonic growth to biofilm, flagellum formation is turned off and the production of fimbriae and extracellular polysaccharides is switched on. BolA is present in most Gram-negative bacteria, and homologues can be found from proteobacteria to eukaryotes. Here, we show that BolA is a new bacterial transcription factor that modulates the switch from a planktonic to a sessile lifestyle. It negatively modulates flagellar biosynthesis and swimming capacity in Escherichia coli. Furthermore, BolA overexpression favors biofilm formation, involving the production of fimbria-like adhesins and curli. Our results also demonstrate that BolA is a protein with high affinity to DNA and is able to regulate many genes on a genome-wide scale. Moreover, we show that the most significant targets of this protein involve a complex network of genes encoding proteins related to biofilm development. Herein, we propose that BolA is a motile/adhesive transcriptional switch, specifically involved in the transition between the planktonic and the attachment stage of biofilm formation. PMID:25691594

  19. Swimming Motility Mediates the Formation of Neutrophil Extracellular Traps Induced by Flagellated Pseudomonas aeruginosa

    PubMed Central

    Sil, Payel; Chassaing, Benoit; Yoo, Dae-goon; Gewirtz, Andrew T.; Goldberg, Joanna B.; McCarter, Linda L.; Rada, Balázs

    2016-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections often characterized by robust neutrophilic infiltration. Neutrophils provide the first line of defense against P. aeruginosa. Aside from their defense conferred by phagocytic activity, neutrophils also release neutrophil extracellular traps (NETs) to immobilize bacteria. Although NET formation is an important antimicrobial process, the details of its mechanism are largely unknown. The identity of the main components of P. aeruginosa responsible for triggering NET formation is unclear. In this study, our focus was to identify the main bacterial factors mediating NET formation and to gain insight into the underlying mechanism. We found that P. aeruginosa in its exponential growth phase promoted strong NET formation in human neutrophils while its NET-inducing ability dramatically decreased at later stages of bacterial growth. We identified the flagellum as the primary component of P. aeruginosa responsible for inducing NET extrusion as flagellum-deficient bacteria remained seriously impaired in triggering NET formation. Purified P. aeruginosa flagellin, the monomeric component of the flagellum, does not stimulate NET formation in human neutrophils. P. aeruginosa-induced NET formation is independent of the flagellum-sensing receptors TLR5 and NLRC4 in both human and mouse neutrophils. Interestingly, we found that flagellar motility, not flagellum binding to neutrophils per se, mediates NET release induced by flagellated bacteria. Immotile, flagellar motor-deficient bacterial strains producing paralyzed flagella did not induce NET formation. Forced contact between immotile P. aeruginosa and neutrophils restored their NET-inducing ability. Both the motAB and motCD genetic loci encoding flagellar motor genes contribute to maximal NET release; however the motCD genes play a more important role. Phagocytosis of P. aeruginosa and superoxide production by neutrophils were also largely dependent upon

  20. Kruger strict morphology and post-thaw progressive motility in cryopreserved human spermatozoa.

    PubMed

    Lee, C-Y; Lee, C-T; Wu, C-H; Hsu, C-S; Hsu, M-I

    2012-05-01

    The purpose of this prospective study was to evaluate Kruger strict morphology and conventional semen analysis in predicting cryosurvival and the progressive motility recovery rate of frozen spermatozoa. Our study included 56 semen samples with >10 million spermatozoa per ejaculate. The main outcome measures were conventional semen analysis, strict morphology analysis by the Kruger method, cryosurvival rate and post-thaw sperm motility. A significant reduction in sperm motility after cryopreservation was demonstrated. The freeze-thawing process caused a 66% reduction in rapid progressive motile spermatozoa, a 45% reduction in slow progressive motile spermatozoa and a 2% reduction in nonprogressive motile spermatozoa. The cryosurvival and progressive motility recovery rates were not correlated with parameters of conventional semen analysis, such as sperm concentration, motility, WHO morphology and total motile count, but the progressive motility recovery rate was significantly correlated with the percentage of spermatozoa exhibiting Kruger normal morphology (P = 0.028). The recovery rate of rapidly progressive motility was profoundly decreased compared with slow progressive motility following the frozen-thaw procedure of semen. Kruger strict morphology assessment was a better predictor of the progressive motility recovery rate following the freezing-thaw procedure than parameters of conventional semen analysis.

  1. The Pseudomonas aeruginosa diguanylate cyclase GcbA, a homolog of P. fluorescens GcbA, promotes initial attachment to surfaces, but not biofilm formation, via regulation of motility.

    PubMed

    Petrova, Olga E; Cherny, Kathryn E; Sauer, Karin

    2014-08-01

    Cyclic di-GMP is a conserved signaling molecule regulating the transitions between motile and sessile modes of growth in a variety of bacterial species. Recent evidence suggests that Pseudomonas species harbor separate intracellular pools of c-di-GMP to control different phenotypic outputs associated with motility, attachment, and biofilm formation, with multiple diguanylate cyclases (DGCs) playing distinct roles in these processes, yet little is known about the potential conservation of functional DGCs across Pseudomonas species. In the present study, we demonstrate that the P. aeruginosa homolog of the P. fluorescens DGC GcbA involved in promoting biofilm formation via regulation of swimming motility likewise synthesizes c-di-GMP to regulate surface attachment via modulation of motility, however, without affecting subsequent biofilm formation. P. aeruginosa GcbA was found to regulate flagellum-driven motility by suppressing flagellar reversal rates in a manner independent of viscosity, surface hardness, and polysaccharide production. P. fluorescens GcbA was found to be functional in P. aeruginosa and was capable of restoring phenotypes associated with inactivation of gcbA in P. aeruginosa to wild-type levels. Motility and attachment of a gcbA mutant strain could be restored to wild-type levels via overexpression of the small regulatory RNA RsmZ. Furthermore, epistasis analysis revealed that while both contribute to the regulation of initial surface attachment and flagellum-driven motility, GcbA and the phosphodiesterase DipA act within different signaling networks to regulate these processes. Our findings expand the complexity of c-di-GMP signaling in the regulation of the motile-sessile switch by providing yet another potential link to the Gac/Rsm network and suggesting that distinct c-di-GMP-modulating signaling pathways can regulate a single phenotypic output.

  2. SIRT1 inhibits the mouse intestinal motility and epithelial proliferation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    SIRT1 inhibits the mouse intestinal motility and epithelial proliferation. Sirtuin 1 (SIRT1), a NAD+-dependent histone deacetylase, is involved in a wide array of cellular processes, including glucose homeostasis, energy metabolism, proliferation and apoptosis, and immune response. However, it is un...

  3. Coherent motility measurements of biological objects in a large volume

    NASA Astrophysics Data System (ADS)

    Ebersberger, J.; Weigelt, G.; Li, Yajun

    1986-05-01

    We have performed space-time intensity cross-correlation measurements of boiling image plane speckle interferograms to investigate the motility of a large number of small biological objects. Experiments were carried out with Artemia Salina species at various water temperatures. The advantage of this method is the fact that many objects in a large volume can be measured simultaneously.

  4. Ribose Accelerates Gut Motility and Suppresses Mouse Body Weight Gaining

    PubMed Central

    Liu, Yan; Li, Tong-Ruei R; Xu, Cong; Xu, Tian

    2016-01-01

    The increasing prevalence of obesity is closely related to excessive energy consumption. Clinical intervention of energy intake is an attractive strategy to fight obesity. However, the current FDA-approved weight-loss drugs all have significant side effects. Here we show that ribose upregulates gut motility and suppresses mice body weight gain. Ribokinase, which is encoded by Rbks gene, is the first enzyme for ribose metabolism in vivo. Rbks mutation resulted in ribose accumulation in the small intestine, which accelerated gut movement. Ribose oral treatment in wild type mice also enhanced bowel motility and rendered mice resistance to high fat diets. The suppressed weight gain was resulted from enhanced ingested food excretion. In addition, the effective dose of ribose didn't cause any known side effects (i.e. diarrhea and hypoglycemia). Overall, our results show that ribose can regulate gut motility and energy homeostasis in mice, and suggest that administration of ribose and its analogs could regulate gastrointestinal motility, providing a novel therapeutic approach for gastrointestinal dysfunction and weight control. PMID:27194947

  5. Is sperm motility maturation affected by static magnetic fields?

    PubMed Central

    Tablado, L; Pérez-Sánchez, F; Soler, C

    1996-01-01

    Kinematic parameters were evaluated in mouse epididymal extracts to monitor maturation of sperm movement in animals exposed to static magnetic fields using the Sperm-Class Analyzer computerized image analysis system. For this purpose, animals were exposed to a field of 0.7 T generated by a permanent magnet over 10 or 35 days for either 1 or 24 hr/day. The values of the motion endpoints were similar in animals used as controls and in those exposed to the nonionizing radiation, whatever the period of exposure or daily dosage. Changes in motility were observed in all groups: the percentage of total motile and progressive motile spermatozoa increased during passage through the epididymis, with major changes between the caput and corpus epididymides, and the pattern of swimming changed clearly towards more rapid and straighter trajectories. The processes of initiation of sperm motility and maturation of displacement patterns were not then affected by magnetic treatment. Moreover, it appears that sperm production is unaffected because no changes were observed in testicular or epididymal weights after exposure to static magnetic fields. Images Figure 1. Figure 2. Figure 3. PMID:8959411

  6. Motility enhancement of bacteria actuated microstructures using selective bacteria adhesion.

    PubMed

    Park, Sung Jun; Bae, Hyeoni; Kim, Joonhwuy; Lim, Byungjik; Park, Jongoh; Park, Sukho

    2010-07-07

    Microrobots developed by the technological advances are useful for application in various fields. Nevertheless, they have limitations with respect to their actuator and motility. Our experiments aim to determine whether a bioactuator using the flagellated bacteria Serratia marcescens would enhance the motility of microrobots. In this study, we investigate that the flagellated bacteria Serratia marcescens could be utilized as actuators for SU-8 microstructures by bovine serum albumin-selective patterning. Firstly, we analyze the adherence of the bacteria to the SU-8 micro cube by selective patterning using 5% BSA. The results show that number of attached-bacteria in the uncoated side of the selectively- coated micro cube with BSA increased by 200% compared with that in all sides of the non treated micro cube. Secondly, the selectively BSA coated micro cube had 210% higher motility than the uncoated micro cube. The results revealed that the bacteria patterned to a specific site using 5% BSA significantly increase the motility of the bacteria actuated microstructure.

  7. HES6 enhances the motility of alveolar rhabdomyosarcoma cells

    SciTech Connect

    Wickramasinghe, Caroline M; Domaschenz, Renae; Amagase, Yoko; Williamson, Daniel; Missiaglia, Edoardo; Shipley, Janet; Murai, Kasumi; Jones, Philip H

    2013-01-01

    Absract: HES6, a member of the hairy-enhancer-of-split family of transcription factors, plays multiple roles in myogenesis. It is a direct target of the myogenic transcription factor MyoD and has been shown to regulate the formation of the myotome in development, myoblast cell cycle exit and the organization of the actin cytoskeleton during terminal differentiation. Here we investigate the expression and function of HES6 in rhabdomyosarcoma, a soft tissue tumor which expresses myogenic genes but fails to differentiate into muscle. We show that HES6 is expressed at high levels in the subset of alveolar rhabdomyosarcomas expressing PAX/FOXO1 fusion genes (ARMSp). Knockdown of HES6 mRNA in the ARMSp cell line RH30 reduces proliferation and cell motility. This phenotype is rescued by expression of mouse Hes6 which is insensitive to HES6 siRNA. Furthermore, expression microarray analysis indicates that the HES6 knockdown is associated with a decrease in the levels of Transgelin, (TAGLN), a regulator of the actin cytoskeleton. Knockdown of TAGLN decreases cell motility, whilst TAGLN overexpression rescues the motility defect resulting from HES6 knockdown. These findings indicate HES6 contributes to the pathogenesis of ARMSp by enhancing both proliferation and cell motility.

  8. Effects of Ergot Alkaloids on Bovine Sperm Motility In Vitro

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ergot alkaloids are synthesized by endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire). Our objective was to determine direct effects of ergot alkaloids (ergotamine, dihydroergotamine and ergonovine) on the motility of bovine spermatozoa in vit...

  9. Linear scleroderma associated with ptosis and motility disorders.

    PubMed Central

    Suttorp-Schulten, M S; Koornneef, L

    1990-01-01

    A case is reported in which an 11-year-old girl developed progressive ptosis and a subsequent motility disorder of the right eye. The diagnosis linear scleroderma en coup de sabre was established. Atrophy of the upper levator palpebral and superior rectus muscle could be shown on CT scan. Images PMID:2223709

  10. Social motility in African trypanosomes: fact or model?

    PubMed

    Bastin, Philippe; Rotureau, Brice

    2015-02-01

    African trypanosomes grown on agarose plates exhibit behaviours akin to social motility. This phenomenon has not been observed in vivo so far but recently turned out to be instrumental in the definition of two specific stages of the parasite cycle and as a tool to probe for trypanosome sensing functions.

  11. Separation of motile bacteria using drift velocity in a microchannel.

    PubMed

    Ishikawa, Takuji; Shioiri, Tatsuya; Numayama-Tsuruta, Keiko; Ueno, Hironori; Imai, Yohsuke; Yamaguchi, Takami

    2014-03-07

    Separation of certain bacteria from liquids is important in the food, water quality management, bioengineering, and pharmaceutical industries. In this study, we developed a microfluidic device for the hydrodynamic separation of motile bacteria (Escherichia coli) using drift velocity. We first investigated drift tendencies of bacteria and found that cells tended to move in a spanwise direction with similar velocities regardless of the flow rate. When the drift distance was small compared to the wetted perimeter of the cross section, the cells were not separated efficiently. We then investigated the drift phenomenon in more detail using a numerical simulation. Interestingly, the drift phenomenon was observed even without a wall boundary, indicating that drift was caused mainly by the interaction of moving cells with the background shear flow. Finally, we developed a microfluidic device to separate motile bacteria from tracer particles or less motile cells. By decreasing the channel height, the device could successfully separate motile bacteria from other particles or cells with a separation efficiency of about 40%. Connecting microchannels in a series was also found to be effective, which achieved the separation efficiency of about 60%. The knowledge obtained in this study will facilitate the development of other microfluidics devices for use with bacteria.

  12. Diffusion of Bacterial Cells in Porous Media

    PubMed Central

    Licata, Nicholas A.; Mohari, Bitan; Fuqua, Clay; Setayeshgar, Sima

    2016-01-01

    The chemotaxis signal transduction network regulates the biased random walk of many bacteria in favorable directions and away from harmful ones through modulating the frequency of directional reorientations. In mutants of diverse bacteria lacking the chemotaxis response, migration in classic motility agar, which constitutes a fluid-filled porous medium, is compromised; straight-swimming cells unable to tumble become trapped within the agar matrix. Spontaneous mutations that restore spreading have been previously observed in the enteric bacterium Escherichia coli, and recent work in other bacterial species has isolated and quantified different classes of nonchemotacting mutants exhibiting the same spreading phenotype. We present a theoretical description of bacterial diffusion in a porous medium—the natural habitat for many cell types—which elucidates how diverse modifications of the motility apparatus resulting in a nonzero tumbling frequency allows for unjamming of otherwise straight-swimming cells at internal boundaries and leads to net migration. A unique result of our analysis is increasing diffusive spread with increasing tumbling frequency in the small pore limit, consistent with earlier experimental observations but not captured by previous models. Our theoretical results, combined with a simple model of bacterial diffusion and growth in agar, are compared with our experimental measurements of swim ring expansion as a function of time, demonstrating good quantitative agreement. Our results suggest that the details of the cellular tumbling process may be adapted to enable bacteria to propagate efficiently through complex environments. For engineered, self-propelled microswimmers that navigate via alternating straight runs and changes in direction, these results suggest an optimal reorientation strategy for efficient migration in a porous environment with a given microarchitecture. PMID:26745427

  13. Borrelia burgdorferi CheY2 Is Dispensable for Chemotaxis or Motility but Crucial for the Infectious Life Cycle of the Spirochete.

    PubMed

    Xu, Hui; Sultan, Syed; Yerke, Aaron; Moon, Ki Hwan; Wooten, R Mark; Motaleb, M A

    2017-01-01

    The requirements for bacterial chemotaxis and motility range from dispensable to crucial for host colonization. Even though more than 50% of all sequenced prokaryotic genomes possess at least one chemotaxis signaling system, many of those genomes contain multiple copies of a chemotaxis gene. However, the functions of most of those additional genes are unknown. Most motile bacteria possess at least one CheY response regulator that is typically dedicated to the control of motility and which is usually essential for virulence. Borrelia burgdorferi appears to be notably different, in that it has three cheY genes, and our current studies on cheY2 suggests that it has varied effects on different aspects of the natural infection cycle. Mutants deficient in this protein exhibit normal motility and chemotaxis in vitro but show reduced virulence in mice. Specifically, the cheY2 mutants were severely attenuated in murine infection and dissemination to distant tissues after needle inoculation. Moreover, while ΔcheY2 spirochetes are able to survive normally in the Ixodes ticks, mice fed upon by the ΔcheY2-infected ticks did not develop a persistent infection in the murine host. Our data suggest that CheY2, despite resembling a typical response regulator, functions distinctively from most other chemotaxis CheY proteins. We propose that CheY2 serves as a regulator for a B. burgdorferi virulence determinant that is required for productive infection within vertebrate, but not tick, hosts.

  14. Role of overexpressed CFA/I fimbriae in bacterial swimming

    NASA Astrophysics Data System (ADS)

    Cao, Ling; Suo, Zhiyong; Lim, Timothy; Jun, SangMu; Deliorman, Muhammedin; Riccardi, Carol; Kellerman, Laura; Avci, Recep; Yang, Xinghong

    2012-06-01

    Enterotoxigenic Escherichia coli CFA/I is a protective antigen and has been overexpressed in bacterial vectors, such as Salmonella Typhimurium H683, to generate vaccines. Effects that overexpressed CFA/I may engender on the bacterial host remain largely unexplored. To investigate, we constructed a high CFA/I expression strain, H683-pC2, and compared it to a low CFA/I expression strain, H683-pC, and to a non-CFA/I expression strain, H683-pY. The results showed that H683-pC2 was less able to migrate into semisolid agar (0.35%) than either H683-pC or H683-pY. Bacteria that migrated showed motility halo sizes of H683-pC2 < H683-pC < H683-pY. In the liquid culture media, H683-pC2 cells precipitated to the bottom of the tube, while those of H683-pY did not. In situ imaging revealed that H683-pC2 bacilli tended to auto-agglutinate within the semisolid agar, while H683-pY bacilli did not. When the cfaBE fimbrial fiber encoding genes were deleted from pC2, the new plasmid, pC2(-), significantly recovered bacterial swimming capability. Our study highlights the negative impact of overexpressed CFA/I fimbriae on bacterial swimming motility.

  15. Quorum sensing in Yersinia enterocolitica controls swimming and swarming motility.

    PubMed

    Atkinson, Steve; Chang, Chien-Yi; Sockett, R Elizabeth; Cámara, Miguel; Williams, Paul

    2006-02-01

    The Yersinia enterocolitica LuxI homologue YenI directs the synthesis of N-3-(oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) and N-hexanoylhomoserine lactone (C6-HSL). In a Y. enterocolitica yenI mutant, swimming motility is temporally delayed while swarming motility is abolished. Since both swimming and swarming are flagellum dependent, we purified the flagellin protein from the parent and yenI mutant. Electrophoresis revealed that in contrast to the parent strain, the yenI mutant grown for 17 h at 26 degrees C lacked the 45-kDa flagellin protein FleB. Reverse transcription-PCR indicated that while mutation of yenI had no effect on yenR, flhDC (the motility master regulator) or fliA (the flagellar sigma factor) expression, fleB (the flagellin structural gene) was down-regulated. Since 3-oxo-C6-HSL and C6-HSL did not restore swimming or swarming in the yenI mutant, we reexamined the N-acylhomoserine lactone (AHL) profile of Y. enterocolitica. Using AHL biosensors and mass spectrometry, we identified three additional AHLs synthesized via YenI: N-(3-oxodecanoyl)homoserine lactone, N-(3-oxododecanoyl)homoserine lactone (3-oxo-C12-HSL), and N-(3-oxotetradecanoyl)homoserine lactone. However, none of the long-chain AHLs either alone or in combination with the short-chain AHLs restored swarming or swimming in the yenI mutant. By investigating the transport of radiolabeled 3-oxo-C12-HSL and by introducing an AHL biosensor into the yenI mutant we demonstrate that the inability of exogenous AHLs to restore motility to the yenI mutant is not related to a lack of AHL uptake. However, both AHL synthesis and motility were restored by complementation of the yenI mutant with a plasmid-borne copy of yenI.

  16. Roles of ion transport in control of cell motility.

    PubMed

    Stock, Christian; Ludwig, Florian T; Hanley, Peter J; Schwab, Albrecht

    2013-01-01

    Cell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life-threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage-sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca(2+) and H(+) concentrations. Voltage-sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca(2+) concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H(+) concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion-transport mechanisms contribute to the various modes of cell motility.

  17. Exopolysaccharide biosynthesis genes required for social motility in Myxococcus xanthus.

    PubMed

    Lu, Ann; Cho, Kyunyung; Black, Wesley P; Duan, Xue-Yan; Lux, Renate; Yang, Zhaomin; Kaplan, Heidi B; Zusman, David R; Shi, Wenyuan

    2005-01-01

    Social (S)-motility in Myxococcus xanthus is a flagellum-independent gliding motility system that allows bacteria to move in groups on solid surfaces. S-motility has been shown to require type IV pili (TFP), exopolysaccharide (EPS; a component of fibrils) and lipopolysaccharide (LPS). Previously, information concerning EPS biogenesis in M. xanthus was lacking. In this study, we screened 5000 randomly mutagenized colonies for defects in S-motility and EPS and identified two genetic regions essential for EPS biogenesis: the EPS synthesis (eps) region and the EPS-associated (eas) region. Mutants with insertions in the eps and eas regions were defective in S-motility and fruiting body formation. These mutants failed to bind the dye calcofluor white, indicating that they lacked EPS; however, they retained normal TFP and LPS. Analysis of the eps locus showed several open reading frames (ORFs) that encode homologues to glycosyltransferases, glucanases and EPS transporters as well as regulatory proteins; the eas locus contains two ORFs: one exhibits homology to hypothetical proteins with a conserved domain of unknown function and the other displays no apparent homology to other proteins in the database. Further genetic mutagenesis analysis indicates that the whole eps region is involved in the biosynthesis of fibrils and fibril EPS. The operon at the proximal end of the eps region was analysed by generating in-frame deletion mutations. These mutants showed varying degrees of defects in the bacterium's ability to produce EPS or perform EPS-related functions, confirming the involvement of these genes in M. xanthus EPS biogenesis.

  18. Gelsolin, a protein that caps the barbed ends and severs actin filaments, enhances the actin-based motility of Listeria monocytogenes in host cells.

    PubMed

    Laine, R O; Phaneuf, K L; Cunningham, C C; Kwiatkowski, D; Azuma, T; Southwick, F S

    1998-08-01

    The actin-based motility of Listeria monocytogenes requires the addition of actin monomers to the barbed or plus ends of actin filaments. Immunofluorescence micrographs have demonstrated that gelsolin, a protein that both caps barbed ends and severs actin filaments, is concentrated directly behind motile bacteria at the junction between the actin filament rocket tail and the bacterium. In contrast, CapG, a protein that strictly caps actin filaments, fails to localize near intracellular Listeria. To explore the effect of increasing concentrations of gelsolin on bacterial motility, NIH 3T3 fibroblasts stably transfected with gelsolin cDNA were infected with Listeria. The C5 cell line containing 2.25 times control levels of gelsolin supported significantly higher velocities of bacterial movement than did control fibroblasts (mean +/- standard error of the mean, 0.09 +/- 0.003 micro(m)/s [n = 176] versus 0.05 +/- 0.003 micro(m)/s [n = 65]). The rate of disassembly of the Listeria-induced actin filament rocket tail was found to be independent of gelsolin content. Therefore, if increases in gelsolin content result in increases in Listeria-induced rocket tail assembly rates, a positive correlation between gelsolin content and tail length would be expected. BODIPY-phalloidin staining of four different stably transfected NIH 3T3 fibroblast cell lines confirmed this expectation (r = 0.92). Rocket tails were significantly longer in cells with a high gelsolin content. Microinjection of gelsolin 1/2 (consisting of the amino-terminal half of native gelsolin) also increased bacterial velocity by more than 2.2 times. Microinjection of CapG had no effect on bacterial movement. Cultured skin fibroblasts derived from gelsolin-null mice were capable of supporting intracellular Listeria motility at velocities comparable to those supported by wild-type skin fibroblasts. These experiments demonstrated that the surface of Listeria contains a polymerization zone that can block the barbed

  19. Effect of the surface composition of motile Escherichia coli and motile Salmonella species on the direction of galvanotaxis.

    PubMed Central

    Shi, W; Stocker, B A; Adler, J

    1996-01-01

    We have reported that motile Escherichia coli K-12 placed in an electric field swims toward the anode but that motile Salmonella typhimurium strains swim toward the cathode, a phenomenon called galvanotaxis (J. Adler and W. Shi, Cold Spring Harbor Symp. Quant. Biol. 53:23-25, 1988). In the present study, we isolated mutants with an altered direction of galvanotaxis. By further analyses of these mutants and by examination of E. coli and Salmonella strains with altered cell surface structure, we have now established a correlation between the direction of galvanotaxis and the surface structure of the cell: motile rough bacteria (that is, those without O polysaccharide; for example, E. coli K-12 and S. typhimurium mutants of classes galE and rfa) swam toward the anode, whereas motile smooth bacteria (that is, those with O polysaccharide; for example, wild-type S. typhimurium LT2) swam toward the cathode. However, smooth bacteria with acidic polysaccharide capsules (K1 in E. coli and Vi in Salmonella typhi) swam toward the anode. Measurements of passive electrophoretic mobility of strains representative of each set were made. We propose that the different directions of galvanotaxis of rough (or capsulate) bacteria and of smooth bacteria are explicable if the negative electrophoretic mobility of flagellar filaments is less than that of rough bodies but greater than that of smooth bodies. PMID:8576046

  20. Norepinephrine and dopamine increase motility, biofilm formation, and virulence of Vibrio harveyi

    PubMed Central

    Yang, Qian; Anh, Nguyen D. Q.; Bossier, Peter; Defoirdt, Tom

    2014-01-01

    Vibrio harveyi is one of the major pathogens of aquatic organisms, affecting both vertebrates and invertebrates, and causes important losses in the aquaculture industry. In order to develop novel methods to control disease caused by this pathogen, we need to obtain a better understanding of pathogenicity mechanisms. Sensing of catecholamines increases both growth and production of virulence-related factors in pathogens of terrestrial animals and humans. However, at this moment, knowledge on the impact of catecholamines on the virulence of pathogens of aquatic organisms is lacking. In the present study, we report that in V. harveyi, norepinephrine (NE) and dopamine (Dopa) increased growth in serum-supplemented medium, siderophore production, swimming motility, and expression of genes involved in flagellar motility, biofilm formation, and exopolysaccharide production. Consistent with this, pretreatment of V. harveyi with catecholamines prior to inoculation into the rearing water resulted in significantly decreased survival of gnotobiotic brine shrimp larvae, when compared to larvae challenged with untreated V. harveyi. Further, NE-induced effects could be neutralized by α-adrenergic antagonists or by the bacterial catecholamine receptor antagonist LED209, but not by β-adrenergic or dopaminergic antagonists. Dopa-induced effects could be neutralized by dopaminergic antagonists or LED209, but not by adrenergic antagonists. Together, our results indicate that catecholamine sensing increases the success of transmission of V. harveyi and that interfering with catecholamine sensing might be an interesting strategy to control vibriosis in aquaculture. We hypothesize that upon tissue and/or hemocyte damage during infection, pathogens come into contact with elevated catecholamine levels, and that this stimulates the expression of virulence factors that are required to colonize a new host. PMID:25414697

  1. EFFECT OF CRYOPRESERVATION AND THEOPHYLLINE ON MOTILITY CHARACTERISTICS OF LAKE STURGEON (ACIPENSER FULVESCENS) SPERMATOZOA

    EPA Science Inventory

    Computer-assisted motility analysis (CASA) was used to evaluate the effect of cryopreservation and theophylline treatment on sperm motility of lake sturgeon (Acipenser fulvescens).Motility was recorded at 0 and 5 min postactivation.The effect of cryopreservation on sperm acrosin-...

  2. OBJECTIVE ANALYSIS OF SPERM MOTILITY IN THE LAKE STURGEON, ACIPENSER FULVESCENS: ACTIVATION AND INHIBITION CONDITIONS

    EPA Science Inventory

    An objective analysis of the duration of motility of sperm from the lake sturgeon, Acipenser fulvescens, has been performed using computer-assisted sperm motion analysis at 200 frames/s. Motility was measured in both 1993 and 1994. The percentage of activated motile sperm and the...

  3. Multiple Pilus Motors Cooperate for Persistent Bacterial Movement in Two Dimensions

    NASA Astrophysics Data System (ADS)

    Holz, Claudia; Opitz, Dirk; Greune, Lilo; Kurre, Rainer; Koomey, Michael; Schmidt, M. Alexander; Maier, Berenike

    2010-04-01

    In various bacterial species surface motility is mediated by cycles of type IV pilus motor elongation, adhesion, and retraction, but it is unclear whether bacterial movement follows a random walk. Here we show that the correlation time of persistent movement in Neisseria gonorrhoeae increases with the number of pili. The unbinding force of individual pili from the surface F=10pN was considerably lower than the stalling force F>100pN, suggesting that density, force, and adhesive properties of the pilus motor enable a tug-of-war mechanism for bacterial movement.

  4. Small bowel bacterial overgrowth: a negative factor in gut adaptation in pediatric SBS.

    PubMed

    Cole, Conrad R; Ziegler, Thomas R

    2007-12-01

    Small bowel bacterial overgrowth (SBBO) is common in infants and children with short bowel syndrome (SBS). Its occurrence is due to alterations in anatomy, motility, and secretion, which promote the abnormal growth of bacteria. SBBO is associated with significant clinical problems, including prolonged dependence on parenteral nutrition, liver injury, and malabsorption. A major clinical challenge is in making the correct diagnosis of bacterial overgrowth. Management of this disorder is still poorly understood and should be evaluated adequately. This review addresses the current understanding of bacteria in the intestines and issues related to bacterial overgrowth in pediatric SBS.

  5. Gadolinium, a mechano-sensitive channel blocker, inhibits osmosis-initiated motility of sea- and freshwater fish sperm, but does not affect human or ascidian sperm motility.

    PubMed

    Krasznai, Zoltán; Morisawa, Masaaki; Krasznai, Zoárd Tibor; Morisawa, Sachiko; Inaba, Kazuo; Bazsáné, Zsuzsa Kassai; Rubovszky, Bálint; Bodnár, Béla; Borsos, Antal; Márián, Teréz

    2003-08-01

    Exposure to hypo-osmotic or hyperosmotic environment triggers the initiation of fish sperm motility. In this article, we report that calcium and potassium channel blockers do not influence motility of puffer fish sperm but calmodulin antagonists reversibly decrease it, suggesting that calmodulin-Ca(2+) interactions are prerequisite for the initiation of sperm motility in this species. Gadolinium (a stretch activated ion channel blocker) decreased the motility of puffer fish sperm from 92 +/- 3% to 6 +/- 3% and that of carp sperm from 91 +/- 7% to 3.5 +/- 4.3% in a dose-dependent manner (10-40 micro M). The effect of gadolinium was reversible, suggesting that stretch activated ion channels participate in the initiation of sperm motility of the two species. Gadolinium inhibits changes in the isoelectric point of certain proteins of puffer fish sperm, which occur when sperm motility is initiated in a hypertonic solution. Anisotropy measurements showed that hypo-osmotic treatment, which initiates carp sperm motility, increased membrane fluidity. When hypo-osmotic treatment was given in the presence of gadolinium, the sperm membrane remained as rigid as in quiescent cells, while motility was blocked. By contrast, gadolinium did not influence the motility parameters of Ciona or human sperm. Based on these lines of evidence, we suggest that conformational changes of mechanosensitive membrane proteins are involved in osmolality-dependent but not osmolality-independent sperm.

  6. The effect of flagellar motor-rotor complexes on twitching motility in P. aeruginosa

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Utada, Andrew; Gibiansky, Maxsim; Xian, Wujing; Wong, Gerard

    2013-03-01

    P. aeruginosa is an opportunistic bacterium responsible for a broad range of biofilm infections. In order for biofilms to form, P. aeruginosa uses different types of surface motility. In the current understanding, flagella are used for swarming motility and type IV pili are used for twitching motility. The flagellum also plays important roles in initial surface attachment and in shaping the architectures of mature biofilms. Here we examine how flagella and pili interact during surface motility, by using cell tracking techniques. We show that the pili driven twitching motility of P. aeruginosa can be affected by the motor-rotor complexes of the flagellar system.

  7. Comprehensive overexpression analysis of cyclic-di-GMP signalling proteins in the phytopathogen Pectobacterium atrosepticum reveals diverse effects on motility and virulence phenotypes.

    PubMed

    Tan, H; West, J A; Ramsay, J P; Monson, R E; Griffin, J L; Toth, I K; Salmond, G P C

    2014-07-01

    Bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous bacterial signalling molecule produced by diguanylate cyclases of the GGDEF-domain family. Elevated c-di-GMP levels or increased GGDEF protein expression is frequently associated with the onset of sessility and biofilm formation in numerous bacterial species. Conversely, phosphodiesterase-dependent diminution of c-di-GMP levels by EAL- and HD-GYP-domain proteins is often accompanied by increased motility and virulence. In this study, we individually overexpressed 23 predicted GGDEF, EAL or HD-GYP-domain proteins encoded by the phytopathogen Pectobacterium atrosepticum strain SCRI1043. MS-based detection of c-di-GMP and 5'-phosphoguanylyl-(3'-5')-guanosine in these strains revealed that overexpression of most genes promoted modest 1-10-fold changes in cellular levels of c-di-GMP, with the exception of the GGDEF-domain proteins ECA0659 and ECA3374, which induced 1290- and 7660-fold increases, respectively. Overexpression of most EAL domain proteins increased motility, while overexpression of most GGDEF domain proteins reduced motility and increased poly-β-1,6-N-acetyl-glucosamine-dependent flocculation. In contrast to domain-based predictions, overexpression of the EAL protein ECA3549 or the HD-GYP protein ECA3548 increased c-di-GMP concentrations and reduced motility. Most overexpression constructs altered the levels of secreted cellulases, pectinases and proteases, confirming c-di-GMP regulation of virulence in Pe. atrosepticum. However, there was no apparent correlation between virulence-factor induction and the domain class expressed or cellular c-di-GMP levels, suggesting that regulation was in response to specific effectors within the network, rather than total c-di-GMP concentration. Finally, we demonstrated that the cellular localization patterns vary considerably for GGDEF/EAL/HD-GYP proteins, indicating it is a likely factor restricting specific interactions within the c

  8. Microbial Morphology and Motility as Biosignatures for Outer Planet Missions

    PubMed Central

    Lindensmith, Chris; Deming, Jody W.; Fernandez, Vicente I.; Stocker, Roman

    2016-01-01

    Abstract Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies. Key Words: In situ measurement—Biosignatures—Microbiology—Europa—Ice. Astrobiology 16, 755–774. PMID:27552160

  9. A Structural Basis for How Motile Cilia Beat.

    PubMed

    Satir, Peter; Heuser, Thomas; Sale, Winfield S

    2014-12-01

    The motile cilium is a mechanical wonder, a cellular nanomachine that produces a high-speed beat based on a cycle of bends that move along an axoneme made of 9+2 microtubules. The molecular motors, dyneins, power the ciliary beat. The dyneins are compacted into inner and outer dynein arms, whose activity is highly regulated to produce microtubule sliding and axonemal bending. The switch point hypothesis was developed long ago to account for how sliding in the presence of axonemal radial spoke-central pair interactions causes the ciliary beat. Since then, a new genetic, biochemical, and structural complexity has been discovered, in part, with Chlamydomonas mutants, with high-speed, high-resolution analysis of movement and with cryoelectron tomography. We stand poised on the brink of new discoveries relating to the molecular control of motility that extend and refine our understanding of the basic events underlying the switching of arm activity and of bend formation and propagation.

  10. A Structural Basis for How Motile Cilia Beat

    PubMed Central

    Satir, Peter; Heuser, Thomas; Sale, Winfield S.

    2014-01-01

    The motile cilium is a mechanical wonder, a cellular nanomachine that produces a high-speed beat based on a cycle of bends that move along an axoneme made of 9+2 microtubules. The molecular motors, dyneins, power the ciliary beat. The dyneins are compacted into inner and outer dynein arms, whose activity is highly regulated to produce microtubule sliding and axonemal bending. The switch point hypothesis was developed long ago to account for how sliding in the presence of axonemal radial spoke–central pair interactions causes the ciliary beat. Since then, a new genetic, biochemical, and structural complexity has been discovered, in part, with Chlamydomonas mutants, with high-speed, high-resolution analysis of movement and with cryoelectron tomography. We stand poised on the brink of new discoveries relating to the molecular control of motility that extend and refine our understanding of the basic events underlying the switching of arm activity and of bend formation and propagation. PMID:26955066

  11. Microbial Morphology and Motility as Biosignatures for Outer Planet Missions

    NASA Astrophysics Data System (ADS)

    Nadeau, Jay; Lindensmith, Chris; Deming, Jody W.; Fernandez, Vicente I.; Stocker, Roman

    2016-10-01

    Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies.

  12. Where to Go: Breaking the Symmetry in Cell Motility

    PubMed Central

    2016-01-01

    Cell migration in the “correct” direction is pivotal for many biological processes. Although most work is devoted to its molecular mechanisms, the cell’s preference for one direction over others, thus overcoming intrinsic random motility, epitomizes a profound principle that underlies all complex systems: the choice of one axis, in structure or motion, from a uniform or symmetric set of options. Explaining directional motility by an external chemo-attractant gradient does not solve but only shifts the problem of causation: whence the gradient? A new study in PLOS Biology shows cell migration in a self-generated gradient, offering an opportunity to take a broader look at the old dualism of extrinsic instruction versus intrinsic symmetry-breaking in cell biology. PMID:27196433

  13. A Random Motility Assay Based on Image Correlation Spectroscopy

    PubMed Central

    Prummer, Michael; Kling, Dorothee; Trefzer, Vanessa; Enderle, Thilo; Zoffmann, Sannah; Prunotto, Marco

    2013-01-01

    We demonstrate the random motility (RAMOT) assay based on image correlation spectroscopy for the automated, label-free, high-throughput characterization of random cell migration. The approach is complementary to traditional migration assays, which determine only the collective net motility in a particular direction. The RAMOT assay is less demanding on image quality compared to single-cell tracking, does not require cell identification or trajectory reconstruction, and performs well on live-cell, time-lapse, phase contrast video microscopy of hundreds of cells in parallel. Effective diffusion coefficients derived from the RAMOT analysis are in quantitative agreement with Monte Carlo simulations and allowed for the detection of pharmacological effects on macrophage-like cells migrating on a planar collagen matrix. These results expand the application range of image correlation spectroscopy to multicellular systems and demonstrate a novel, to our knowledge, migration assay with little preparative effort. PMID:23746508

  14. Voltage- and calcium-dependent motility of saccular hair bundles

    NASA Astrophysics Data System (ADS)

    Quiñones, Patricia M.; Meenderink, Sebastiaan W. F.; Bozovic, Dolores

    2015-12-01

    Active bundle motility, which is hypothesized to supply feedback for mechanical amplification of signals, is thought to enhance sensitivity and sharpen tuning in vestibular and auditory organs. To study active hair bundle motility, we combined high-speed camera recordings of bullfrog sacculi, which were mounted in a two-compartment chamber, and voltage-clamp of the hair cell membrane potential. Using this paradigm, we measured three types of bundle motions: 1) spontaneous oscillations which can be analyzed to measure the physiological operating range of the transduction channel; 2) a sustained quasi-static movement of the bundle that depends on membrane potential; and 3) a fast, transient and asymmetric movement that resets the bundle position and depends on changes in the membrane potential. These data support a role for both calcium and voltage in the transduction-channel function.

  15. Biochemistry of actomyosin-dependent cell motility (a review).

    PubMed Central

    Korn, E D

    1978-01-01

    Actins and myosins similar to the major proteins of muscle are the major molecular components of intricate mechanochemical systems that perform numerous vital motility and structural functions in all eukaryotic cells. In this article, after a brief summary of the morphological distribution and ultrastructure of actin, myosin, and interrelated proteins of nonmuscle cells, our present knowledge of their biochemistry is critically appraised from the perspective that understanding complex cellular processes depends ultimately on the identification, purification, and biochemical characterization of the proteins involved. Although few conclusions are reached, possible molecular mechanisms for cellular regulation of actin polymerization, filament association, actomyosin ATPase activity, and mechanochemical coupling are discussed and a number of potentially fruitful directions for further research are suggested. These include comparative biochemical investigations and the study of the interaction of heterologous proteins, but particular emphasis is given to the need for quantitative studies at the molecular level of motility proteins purified from a single cellular source. PMID:147464

  16. Physical models of collective cell motility: from cell to tissue

    NASA Astrophysics Data System (ADS)

    Camley, B. A.; Rappel, W.-J.

    2017-03-01

    In this article, we review physics-based models of collective cell motility. We discuss a range of techniques at different scales, ranging from models that represent cells as simple self-propelled particles to phase field models that can represent a cell’s shape and dynamics in great detail. We also extensively review the ways in which cells within a tissue choose their direction, the statistics of cell motion, and some simple examples of how cell–cell signaling can interact with collective cell motility. This review also covers in more detail selected recent works on collective cell motion of small numbers of cells on micropatterns, in wound healing, and the chemotaxis of clusters of cells.

  17. Persistence-driven durotaxis: Generic, directed motility in rigidity gradients

    PubMed Central

    Novikova, Elizaveta A.; Raab, Matthew; Discher, Dennis E.; Storm, Cornelis

    2017-01-01

    Cells move differently on substrates with different elasticities. In particular, the persistence time of their motion is higher on stiffer substrates. We show that this behavior will result in a net transport of cells directed up a soft-to-stiff gradient. Using simple random walk models with controlled persistence and stochastic simulations, we characterize this propensity to move in terms of the durotactic index measured in experiments. A one-dimensional model captures the essential features of this motion and highlights the competition between diffusive spreading and linear, wavelike propagation. Since the directed motion is rooted in a non-directional change in the behavior of individual cells, the motility is a kinesis rather than a taxis. Persistence-driven durokinesis is generic and may be of use in the design of instructive environments for cells and other motile, mechanosensitive objects. PMID:28256894

  18. Motility precedes egress of malaria parasites from oocysts

    PubMed Central

    Klug, Dennis; Frischknecht, Friedrich

    2017-01-01

    Malaria is transmitted when an infected Anopheles mosquito deposits Plasmodium sporozoites in the skin during a bite. Sporozoites are formed within oocysts at the mosquito midgut wall and are released into the hemolymph, from where they invade the salivary glands and are subsequently transmitted to the vertebrate host. We found that a thrombospondin-repeat containing sporozoite-specific protein named thrombospondin-releated protein 1 (TRP1) is important for oocyst egress and salivary gland invasion, and hence for the transmission of malaria. We imaged the release of sporozoites from oocysts in situ, which was preceded by active motility. Parasites lacking TRP1 failed to migrate within oocysts and did not egress, suggesting that TRP1 is a vital component of the events that precede intra-oocyst motility and subsequently sporozoite egress and salivary gland invasion. DOI: http://dx.doi.org/10.7554/eLife.19157.001 PMID:28115054

  19. Microbial Morphology and Motility as Biosignatures for Outer Planet Missions.

    PubMed

    Nadeau, Jay; Lindensmith, Chris; Deming, Jody W; Fernandez, Vicente I; Stocker, Roman

    2016-10-01

    Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies. Key Words: In situ measurement-Biosignatures-Microbiology-Europa-Ice. Astrobiology 16, 755-774.

  20. Motility contrast imaging of live porcine cumulus-oocyte complexes

    NASA Astrophysics Data System (ADS)

    An, Ran; Turek, John; Machaty, Zoltan; Nolte, David

    2013-02-01

    Freshly-harvested porcine oocytes are invested with cumulus granulosa cells in cumulus-oocyte complexes (COCs). The cumulus cell layer is usually too thick to image the living oocyte under a conventional microscope. Therefore, it is difficult to assess the oocyte viability. The low success rate of implantation is the main problem for in vitro fertilization. In this paper, we demonstrate our dynamic imaging technique called motility contrast imaging (MCI) that provides a non-invasive way to monitor the COCs before and after maturation. MCI shows a change of intracellular activity during oocyte maturation, and a measures dynamic contrast between the cumulus granulosa shell and the oocytes. MCI also shows difference in the spectral response between oocytes that were graded into quality classes. MCI is based on shortcoherence digital holography. It uses intracellular motility as the endogenous imaging contrast of living tissue. MCI presents a new approach for cumulus-oocyte complex assessment.

  1. High Temperature and Bacteriophages Can Indirectly Select for Bacterial Pathogenicity in Environmental Reservoirs

    PubMed Central

    Friman, Ville-Petri; Hiltunen, Teppo; Jalasvuori, Matti; Lindstedt, Carita; Laanto, Elina; Örmälä, Anni-Maria; Laakso, Jouni; Mappes, Johanna; Bamford, Jaana K. H.

    2011-01-01

    The coincidental evolution hypothesis predicts that traits connected to bacterial pathogenicity could be indirectly selected outside the host as a correlated response to abiotic environmental conditions or different biotic species interactions. To investigate this, an opportunistic bacterial pathogen, Serratia marcescens, was cultured in the absence and presence of the lytic bacteriophage PPV (Podoviridae) at 25°C and 37°C for four weeks (N = 5). At the end, we measured changes in bacterial phage-resistance and potential virulence traits, and determined the pathogenicity of all bacterial selection lines in the Parasemia plantaginis insect model in vivo. Selection at 37°C increased bacterial motility and pathogenicity but only in the absence of phages. Exposure to phages increased the phage-resistance of bacteria, and this was costly in terms of decreased maximum population size in the absence of phages. However, this small-magnitude growth cost was not greater with bacteria that had evolved in high temperature regime, and no trade-off was found between phage-resistance and growth rate. As a result, phages constrained the evolution of a temperature-mediated increase in bacterial pathogenicity presumably by preferably infecting the highly motile and virulent bacteria. In more general perspective, our results suggest that the traits connected to bacterial pathogenicity could be indirectly selected as a correlated response by abiotic and biotic factors in environmental reservoirs. PMID:21423610

  2. Presence of calcium-binding motifs in PilY1 homologs correlates with Ca-mediated twitching motility and evolutionary history across diverse bacteria.

    PubMed

    Parker, Jennifer K; Cruz, Luisa F; Evans, Michael R; De La Fuente, Leonardo

    2015-02-01

    Twitching motility, involving type IV pili, is essential for host colonization and virulence of many pathogenic bacteria. Studies of PilY1, a tip-associated type IV pili protein, indicate that PilY1 functions as a switch between pilus extension and retraction, resulting in twitching motility. Recent work detected a calcium-binding motif in PilY1 of some animal bacterial pathogens and demonstrated that binding of calcium to PilY1 with this motif regulates twitching. Though studies of PilY1 in non-animal pathogens are limited, our group demonstrated that twitching motility in the plant pathogen Xylella fastidiosa, which contains three PilY1 homologs, is increased by calcium supplementation. A study was conducted to investigate the phylogenetic relationship between multiple PilY1 homologs, the presence of calcium-binding motifs therein, and calcium-mediated twitching motility across diverse bacteria. Strains analyzed contained one to three PilY1 homologs, but phylogenetic analyses indicated that PilY1 homologs containing the calcium-binding motif Dx[DN]xDGxxD are phylogenetically divergent from other PilY1 homologs. Plant-associated bacteria included in these analyses were then examined for a calcium-mediated twitching response. Results indicate that bacteria must have at least one PilY1 homolog containing the Dx[DN]xDGxxD motif to display a calcium-mediated increase in twitching motility, which likely reflects an adaption to environmental calcium concentrations.

  3. Spontaneous redistribution of surface immunoglobulin in the motile B lymphocyte

    PubMed Central

    1976-01-01

    This paper reports that B cells undergoing translatory motion spontaneously segregate their surface Ig to one portion of their plasma membrane. The spontaneous redistribution of surface Ig was found to be: (a) selective, concanavalin A-dependent on translatory motion and energy metabolism. Abundant B cells undergoing motility were found after cultures in lipopolysaccharide or trypsin, or after brief exposure to cholinergic drugs. PMID:1087328

  4. The Semen pH Affects Sperm Motility and Capacitation.

    PubMed

    Zhou, Ji; Chen, Li; Li, Jie; Li, Hongjun; Hong, Zhiwei; Xie, Min; Chen, Shengrong; Yao, Bing

    2015-01-01

    As the chemical environment of semen can have a profound effect on sperm quality, we examined the effect of pH on the motility, viability and capacitation of human sperm. The sperm in this study was collected from healthy males to avoid interference from other factors. The spermatozoa cultured in sperm nutrition solution at pH 5.2, 6.2, 7.2 and 8.2 were analyzed for sperm total motility, progressive motility (PR), hypo-osmotic swelling (HOS) rate, and sperm penetration. Our results showed that these parameters were similar in pH 7.2 and 8.2 sperm nutrition solutions, but decreased in pH 5.2 and 6.2 solutions. The HOS rate exhibited positive correlation with the sperm total motility and PR. In addition, the sperm Na(+)/K(+)-ATPase activity at different pHs was measured, and the enzyme activity was significantly lower in pH 5.2 and 6.2 media, comparing with that in pH 8.2 and pH 7.2 solutions. Using flow cytometry (FCM) and laser confocal scanning microscopy (LCSM) analysis, the intracellular Ca2(+ )concentrations of sperm cultured in sperm capacitation solution at pH 5.2, 6.2, 7.2 and 8.2 were determined. Compared with that at pH 7.2, the mean fluorescence intensity of sperm in pH 5.2 and 6.2 media decreased significantly, while that of pH 8.2 group showed no difference. Our results suggested that the declined Na(+)/K(+)-ATPase activity at acidic pHs result in decreased sperm movement and capacitation, which could be one of the mechanisms of male infertility.

  5. Effect of pre-freezing conditions on the progressive motility recovery rate of human frozen spermatozoa.

    PubMed

    Zhang, X; Zhou, Y; Xia, W; Wu, H; Yao, K; Liu, H; Xiong, C

    2012-10-01

    We evaluated the effects of sperm concentration, progressive motility, sperm morphology, duration of abstinence and collection season on the progressive motility recovery rate of human frozen spermatozoa to identify characteristics that predict the progressive motility recovery rate of human frozen spermatozoa and improve the protocol for sperm collecting in sperm banks. A total of 14 190 semen samples donated at Zhejiang human sperm bank of China between September 2006 and June 2011 were collected from 1624 donors. Semen was evaluated according to WHO standard procedures for sperm concentration. Progressive motility, sperm morphology, ejaculate collection season and abstinence time were recorded. After freezing and thawing, the progressive motility was assessed. Results showed that sperm concentration, progressive motility and normal morphology were significantly associated with the progressive motility recovery rate of human frozen spermatozoa. In addition, the abstinence time and collection season also significantly affected progressive motility recovery rate. Our results indicated that sperm concentration, progressive motility and normal morphology could be valuable in predicting the progressive motility recovery rate of human frozen spermatozoa. As such, progressive motility recovery may be improved by donating semen when abstinent for 3-5 days and during seasons other than summer.

  6. Actin-Based Motility of Intracellular Microbial Pathogens

    PubMed Central

    Goldberg, Marcia B.

    2001-01-01

    A diverse group of intracellular microorganisms, including Listeria monocytogenes, Shigella spp., Rickettsia spp., and vaccinia virus, utilize actin-based motility to move within and spread between mammalian host cells. These organisms have in common a pathogenic life cycle that involves a stage within the cytoplasm of mammalian host cells. Within the cytoplasm of host cells, these organisms activate components of the cellular actin assembly machinery to induce the formation of actin tails on the microbial surface. The assembly of these actin tails provides force that propels the organisms through the cell cytoplasm to the cell periphery or into adjacent cells. Each of these organisms utilizes preexisting mammalian pathways of actin rearrangement to induce its own actin-based motility. Particularly remarkable is that while all of these microbes use the same or overlapping pathways, each intercepts the pathway at a different step. In addition, the microbial molecules involved are each distinctly different from the others. Taken together, these observations suggest that each of these microbes separately and convergently evolved a mechanism to utilize the cellular actin assembly machinery. The current understanding of the molecular mechanisms of microbial actin-based motility is the subject of this review. PMID:11729265

  7. EFFECTS OF METHYLNALTREXONE ON GUINEA PIG GASTROINTESTINAL MOTILITY

    PubMed Central

    Anselmi, Laura; Huynh, Jennifer; Vegezzi, Gaia; Sternini, Catia

    2013-01-01

    The purpose of the present study was to compare the effects of methylnaltrexone (MNTX), a peripherally acting μ opioid receptor (μOR) antagonist, on gastrointestinal (GI) motility in naïve vs. opiate-chronically treated guinea pigs in vitro and in vivo. We have used the electrically stimulated muscle twitch contractions of longitudinal muscle-myenteric plexus (LMMP) preparations and total GI transit as measure of GI motility. In LMMP preparations of naïve guinea pigs, MNTX (1–30 μM) induced a significant, dose-response reduction of morphine-induced inhibition of electrically stimulated muscle twitch contractions, with an IC50 of 9.4 10−8M. By contrast, MNTX abolished the inhibitory effect of acute morphine at any concentration tested (1–30 μM) in the guinea pigs chronically treated with opiates. In vivo, MNTX (10–50 mg s.c.) did not affect GI transit in naïve guinea pigs when administered acutely or for 5 consecutive days, but reversed the GI transit delay induced by chronic morphine treatment. These findings show that MNTX is effective in reversing opiate-induced inhibition of GI motility acting at peripheral μORs, but does not exert a pharmacologic effect on GI transit in the absence of opiate stimulation. PMID:23361094

  8. Memo mediates ErbB2-driven cell motility.

    PubMed

    Marone, Romina; Hess, Daniel; Dankort, David; Muller, William J; Hynes, Nancy E; Badache, Ali

    2004-06-01

    Clinical studies have revealed that cancer patients whose tumours have increased ErbB2 expression tend to have more aggressive, metastatic disease, which is associated with parameters predicting a poor outcome. The molecular basis underlying ErbB2-dependent cell motility and metastases formation, however, still remains poorly understood. In this study, we show that activation of a set of signalling molecules, including MAPK, phosphatidylinositol-3-OH kinase (PI(3)K) and Src, is required for Neu/ErbB2-dependent lamellipodia formation and for motility of breast carcinoma cells. Stimulation of these molecules, however, failed to induce efficient cell migration in the absence of Neu/ErbB2 phosphorylation at Tyr 1201 or Tyr 1227. We describe a novel molecule, Memo (mediator of ErbB2-driven cell motility), that interacts with a phospho-Tyr 1227-containing peptide, most probably through the Shc adaptor protein. After Neu/ErbB2 activation, Memo-defective cells form actin fibres and grow lamellipodia, but fail to extend microtubules towards the cell cortex. Our data suggest that Memo controls cell migration by relaying extracellular chemotactic signals to the microtubule cytoskeleton.

  9. Exopolysaccharides promote Myxococcus xanthus social motility by inhibiting cellular reversals.

    PubMed

    Zhou, Tianyi; Nan, Beiyan

    2017-02-01

    The biofilm-forming bacterium Myxococcus xanthus moves on surfaces as structured swarms utilizing type IV pili-dependent social (S) motility. In contrast to isolated cells that reverse their moving direction frequently, individual cells within swarms rarely reverse. The regulatory mechanisms that inhibit cellular reversal and promote the formation of swarms are not well understood. Here we show that exopolysaccharides (EPS), the major extracellular components of M. xanthus swarms, inhibit cellular reversal in a concentration-dependent manner. Thus, individual wild-type cells reverse less frequently in swarms due to high local EPS concentrations. In contrast, cells defective in EPS production hyper-reverse their moving direction and show severe defects in S-motility. Surprisingly, S-motility and wild-type reversal frequency are restored in double mutants that are defective in both EPS production and the Frz chemosensory system, indicating that EPS regulates cellular reversal in parallel to the Frz pathway. Here we clarify that besides functioning as the structural scaffold in biofilms, EPS is a self-produced signal that coordinates the group motion of the social bacterium M. xanthus.

  10. Current concepts of mechanical and neural factors in ocular motility

    PubMed Central

    Demer, Joseph L.

    2007-01-01

    Purpose of review The oculomotor periphery was classically regarded as a simple mechanism executing complex behaviors specified explicitly by neural commands. A competing view has emerged that many important aspects of ocular motility are properties of the extraocular muscles and their associated connective tissue pulleys. This review considers current concepts regarding aspects of ocular motility that are mechanically determined versus those that are specified explicitly as innervation. Recent findings While it was established several years ago that the rectus extraocular muscles have connective tissue pulleys, recent functional imaging and histology has suggested that the rectus pulley array constitutes an inner mechanism, analogous to a gimbal, that is rotated torsionally around the orbital axis by an outer mechanism driven by the oblique extraocular muscles. This arrangement may account mechanically for several commutative aspects of ocular motor control, including Listing’s Law, yet permits implementation of non-commutative motility. Recent human behavioral studies, as well as neurophysiology in monkeys, are consistent with implementation of Listing’s Law in the oculomotor periphery, rather than centrally. Summary Varied evidence now strongly supports the conclusion that Listing’s Law and other important ocular kinematics are mechanically determined. This finding implies more limited possibilities for neural adaptation to some ocular motor pathologies, but indicates possibilities for surgical treatments. PMID:16415671

  11. Drosophila Sperm Motility in the Reproductive Tract1

    PubMed Central

    Yang, Yong; Lu, Xiangyi

    2011-01-01

    Motile cilia and flagella exhibit many waveforms as outputs of dynein activation sequences on the highly conserved axoneme. Motility change of sperm in the reproductive tract is difficult to study and remains an important area of investigation. Sperm typically execute a sinusoidal waveform. Increased viscosity in the medium induces somewhat unusual arc-line and helical waveforms in some sperm. However, whether the latter two waveforms occur in vivo is not known. Using green fluorescence protein imaging, we show that Drosophila sperm in the uterus move in circular foci via arc-line waves, predominantly in a tail-leading orientation. From the uterus, a small fraction of the sperm enters the seminal receptacle (SR) in parallel formations. After sperm storage and coincident with fertilization of the egg, the sperm exit the SR via head-leading helical waves. Consistent with the observed bidirectional movements, the sperm show the ability to propagate both base-to-tip and tip-to-base flagellar waves. Numerous studies have shown that sperm motility is regulated by intraflagellar calcium concentrations; in particular, the Pkd2 calcium channel has been shown to affect sperm storage. Our analyses here suggest that Pkd2 is required for the sperm to adopt the correct waveform and movement orientation during SR entry. A working model for the sperm's SR entry movement is proposed. PMID:21293028

  12. Networked Chemoreceptors Benefit Bacterial Chemotaxis Performance

    PubMed Central

    Frank, Vered; Piñas, Germán E.; Cohen, Harel; Parkinson, John S.

    2016-01-01

    ABSTRACT Motile bacteria use large receptor arrays to detect and follow chemical gradients in their environment. Extended receptor arrays, composed of networked signaling complexes, promote cooperative stimulus control of their associated signaling kinases. Here, we used structural lesions at the communication interface between core complexes to create an Escherichia coli strain with functional but dispersed signaling complexes. This strain allowed us to directly study how networking of signaling complexes affects chemotactic signaling and gradient-tracking performance. We demonstrate that networking of receptor complexes provides bacterial cells with about 10-fold-heightened detection sensitivity to attractants while maintaining a wide dynamic range over which receptor adaptational modifications can tune response sensitivity. These advantages proved especially critical for chemotaxis toward an attractant source under conditions in which bacteria are unable to alter the attractant gradient. PMID:27999161

  13. Bacterial energy taxis: a global strategy?

    PubMed

    Schweinitzer, Tobias; Josenhans, Christine

    2010-07-01

    A functional energy metabolism is one of the most important requirements for survival of all kinds of organisms including bacteria. Therefore, many bacteria actively seek conditions of optimal metabolic activity, a behaviour which can be termed "energy taxis". Motility, combined with the sensory perception of the internal energetic conditions, is prerequisite for tactic responses to different energy levels and metabolic yields. Diverse mechanisms of energy sensing and tactic response have evolved among various bacteria. Many of the known energy taxis sensors group among the methyl-accepting chemotaxis protein (MCP)-like sensors. This review summarizes recent advances in the field of energy taxis and explores the current concept that energy taxis is an important part of the bacterial behavioural repertoire in order to navigate towards more favourable metabolic niches and to survive in a specific habitat.

  14. Diffusion of Ellipsoids in Bacterial Suspensions

    NASA Astrophysics Data System (ADS)

    Peng, Yi; Lai, Lipeng; Tai, Yi-Shu; Zhang, Kechun; Xu, Xinliang; Cheng, Xiang

    2016-02-01

    Active fluids such as swarming bacteria and motile colloids exhibit exotic properties different from conventional equilibrium materials. As a peculiar example, a spherical tracer immersed inside active fluids shows an enhanced translational diffusion, orders of magnitude stronger than its intrinsic Brownian motion. Here, rather than spherical tracers, we investigate the diffusion of isolated ellipsoids in a quasi-two-dimensional bacterial bath. Our study shows a nonlinear enhancement of both translational and rotational diffusions of ellipsoids. More importantly, we uncover an anomalous coupling between particles' translation and rotation that is strictly prohibited in Brownian diffusion. The coupling reveals a counterintuitive anisotropic particle diffusion, where an ellipsoid diffuses fastest along its minor axis in its body frame. Combining experiments with theoretical modeling, we show that such an anomalous diffusive behavior arises from the generic straining flow of swimming bacteria. Our work illustrates an unexpected feature of active fluids and deepens our understanding of transport processes in microbiological systems.

  15. Aerotactic Cell Density Variations in Bacterial Turbulence

    NASA Astrophysics Data System (ADS)

    Fernandez, Vicente; Smriga, Steven; Menolascina, Filippo; Rusconi, Roberto; Stocker, Roman

    2015-11-01

    Concentrated suspensions of motile bacteria such as Bacillus subtilis exhibit group dynamics much larger than the scale of an individual bacterium, visual similar to high Reynolds number turbulence. These suspensions represent a microscale realization of active matter. Individually, B. subtilis are also aerotactic, and will accumulate near oxygen sources. Using a microfluidic device for generating oxygen gradients, we investigate the relationship between individuals' attraction to oxygen and the collective motion resultant from hydrodynamic interactions. We focus on changes in density revealed by a fluorescently labeled sub-population of B. subtilis in the dense suspension. This approach allows us to examine changes in density during the onset of collective motion as well as fully developed bacterial turbulence.

  16. Sperm motility-initiating substance in newt egg-jelly induces differential initiation of sperm motility based on sperm intracellular calcium levels.

    PubMed

    Watanabe, Akihiko; Takayama-Watanabe, Eriko; Vines, Carol A; Cherr, Gary N

    2011-01-01

    Sperm motility-initiating substance (SMIS), a novel motility inducer from newt egg-jelly, is activated by the release from associated jelly substances at the beginning of internal fertilization and affects female-stored sperm. We examined motility initiation kinetics of newt sperm in response to SMIS by monitoring the changes of sperm intracellular calcium ([Ca²(+)](i)). In quiescent non-motile sperm loaded with the Ca²(+) indicator Fluo-4, intracellular free Ca²(+) was observed around mitochondria using confocal scanning laser microscopy. A slight increase in [Ca²(+)](i) occurred simultaneously and transiently at motility initiation in sperm treated with either heated jelly extract (hJE) containing activated SMIS, or a low osmotic solution, which naturally initiates motility in externally-fertilizing amphibians and can initiate motility in urodele sperm. When the increase of [Ca²(+)](i) at motility-initiation was monitored using spectrofluorometry, large increases in [Ca²(+)](i) occurred immediately in the low osmotic solution and within 1.5 min in the hJE. In the intact jelly extract (no heating), small increases of [Ca²(+)](i) irregularly occurred from around 1 min and for about 4 min, during which motility was differentially initiated among sperm. These results indicate that the SMIS induces differential initiation of sperm motility depending on the activational states of the SMIS and its overall activity. The motility initiation in the jelly extract was delayed in sperm whose intracellular Ca²(+) had been chelated with BAPTA-AM. The relative levels of [Ca²(+)](i) were variable with a mean of 414 ± 256 nmol/L among resting sperm, suggesting that the level of [Ca²(+)](i) in the resting sperm modulates the responsiveness to the SMIS.

  17. Bacterial Transport and Fate and Its Effect on Horizontal Gene Transfer in Soil

    NASA Astrophysics Data System (ADS)

    Lv, N.; Massoudieh, A.; Nguyen, T. H.; Kamai, T.; Zilles, J. L.; Ginn, T. R.; Liang, X.

    2013-12-01

    Biogeochemical cycling in ecosystems relies heavily on soil bacterial communities. Bacterial communities adapt to natural or anthropogenic disruptions through mutation and horizontal gene transfer. Horizontal gene transfer alters bacterial communities rapidly by transferring DNA across species. A systematic understanding of bacterial transport and fate and its effects on horizontal gene transfer is critical for predicting and harnessing bacterial adaption and evolution in soil. In this work, a multi-scale approach was applied to study the effects of both flagella and motility on transport and fate of the soil bacterium Azotobacter vinelandii in porous media. Both micromodel and column experiments showed decreasing deposition over time, suggesting that both flagellated and non-flagellated cells were blocked from deposition by previously deposited cells. In later stages, ripening effects were also observed, and they appeared earlier for the non-flagellated strain. Based on the overall clean collector removal efficiencies determined from micromodel and column experiments, the non-motile and non-flagellated strain DJNM deposited the most, while the motile, wild-type strain DJ showed the least deposition. The overall clean collector removal efficiencies was due to decreased deposition of motile cells on the front sides of the collectors (relative to the flow direction). The horizontal gene transfer of extracellular DNA, known as natural transformation, was evaluated with both dissolved and adsorbed extracellular DNA and with motile and non-motile but flagellated strains (DJ and DJ77, respectively). The distinct transport mechanisms of these strains resulted in different natural transformation rates and relationships to the concentration of cells and dissolved extracellular DNA. A modified mass action type relationship with power relationships was established to model the differences in natural transformation between DJ and DJ77. A cell-DNA pairing hypothesis was

  18. Characterization of Pro-Inflammatory Flagellin Proteins Produced by Lactobacillus ruminis and Related Motile Lactobacilli

    PubMed Central

    Neville, B. Anne; Forde, Brian M.; Claesson, Marcus J.; Darby, Trevor; Coghlan, Avril; Nally, Kenneth; Ross, R. Paul; O’Toole, Paul W.

    2012-01-01

    Lactobacillus ruminis is one of at least twelve motile but poorly characterized species found in the genus Lactobacillus. Of these, only L. ruminis has been isolated from mammals, and this species may be considered as an autochthonous member of the gastrointestinal microbiota of humans, pigs and cows. Nine L. ruminis strains were investigated here to elucidate the biochemistry and genetics of Lactobacillus motility. Six strains isolated from humans were non-motile while three bovine isolates were motile. A complete set of flagellum biogenesis genes was annotated in the sequenced genomes of two strains, ATCC25644 (human isolate) and ATCC27782 (bovine isolate), but only the latter strain produced flagella. Comparison of the L. ruminis and L. mali DSM20444T motility loci showed that their genetic content and gene-order were broadly similar, although the L. mali motility locus was interrupted by an 11.8 Kb region encoding rhamnose utilization genes that is absent from the L. ruminis motility locus. Phylogenetic analysis of 39 motile bacteria indicated that Lactobacillus motility genes were most closely related to those of motile carnobacteria and enterococci. Transcriptome analysis revealed that motility genes were transcribed at a significantly higher level in motile L. ruminis ATCC27782 than in non-motile ATCC25644. Flagellin proteins were isolated from L. ruminis ATCC27782 and from three other Lactobacillus species, while recombinant flagellin of aflagellate L. ruminis ATCC25644 was expressed and purified from E. coli. These native and recombinant Lactobacillus flagellins, and also flagellate L. ruminis cells, triggered interleukin-8 production in cultured human intestinal epithelial cells in a manner suppressed by short interfering RNA directed against Toll-Like Receptor 5. This study provides genetic, transcriptomic, phylogenetic and immunological insights into the trait of flagellum-mediated motility in the lactobacilli. PMID:22808200

  19. Resource level affects relative performance of the two motility systems of Myxococcus xanthus.

    PubMed

    Hillesland, Kristina L; Velicer, Gregory J

    2005-05-01

    The adventurous (A) and social (S) motility systems of the microbial predator Myxococcus xanthus show differential swarming performance on distinct surface types. Under standard laboratory conditions, A-motility performs well on hard agar but poorly on soft agar, whereas the inverse pattern is shown by S-motility. These properties may allow M. xanthus to swarm effectively across a greater diversity of natural surfaces than would be possible with one motility system alone. Nonetheless, the range of ecological conditions under which dual motility enhances effective swarming across distinct surfaces and how ecological parameters affect the complementarity of A-motility and S-motility remain unclear. Here we have examined the role of nutrient concentration in determining swarming patterns driven by dual motility on distinct agar surfaces, as well as the relative contributions of A-motility and S-motility to these patterns. Swarm expansion rates of dually motile (A+S+), solely A-motile (A+S-), and solely S-motile (A-S+) strains were compared on hard and soft agar across a wide range of casitone concentrations. At low casitone concentrations (0-0.1%), swarming on soft agar driven by S-motility is very poor, and is significantly slower than swarming on hard agar driven by A-motility. This reverses at high casitone concentration (1-3.2%) such that swarming on soft agar is much faster than swarming on hard agar. This pattern greatly constrained the ability of M. xanthus to encounter patches of prey bacteria on a soft agar surface when nutrient levels between the patches were low. The swarming patterns of a strain that is unable to produce extracellular fibrils indicate that these appendages are responsible for the elevated swarming of S-motility at high resource levels. Together, these data suggest that large contributions by S-motility to predatory swarming in natural soils may be limited to soft, wet, high-nutrient conditions that may be uncommon. Several likely benefits

  20. Sperm motility of externally fertilizing fish and amphibians.

    PubMed

    Browne, R K; Kaurova, S A; Uteshev, V K; Shishova, N V; McGinnity, D; Figiel, C R; Mansour, N; Agney, D; Wu, M; Gakhova, E N; Dzyuba, B; Cosson, J

    2015-01-01

    We review the phylogeny, sperm competition, morphology, physiology, and fertilization environments of the sperm of externally fertilizing fish and amphibians. Increased sperm competition in both fish and anurans generally increases sperm numbers, sperm length, and energy reserves. The difference between the internal osmolarity and iconicity of sperm cells and those of the aquatic medium control the activation, longevity, and velocity of sperm motility. Hypo-osmolarity of the aquatic medium activates the motility of freshwater fish and amphibian sperm and hyperosmolarity activates the motility of marine fish sperm. The average longevity of the motility of marine fish sperm (~550 seconds) was significantly (P < 0.05) greater than that of freshwater fish sperm (~150 seconds), with the longevities of both marine and freshwater fish being significantly (P < 0.05) lower than that of anuran sperm (~4100 seconds). The average velocity of anuran sperm (25 μm/s) was significantly (P < 0.05) lower than that of marine fish (140 μm/s) or freshwater fish (135 μm/s) sperm. The longevity of the sperm of giant salamanders (Cryptobranchoidea) of approximately 600 seconds was greater than that of freshwater fish sperm but much lower than anuran sperm. Our research and information from the literature showed that higher osmolarities promote greater longevity in anuran sperm, and some freshwater fish sperm, and that anuran and cryptobranchid sperm maintained membrane integrity long after the cessation of motility, demonstrating a preferential sharing of energy reserves toward the maintenance of membrane integrity. The maintenance of the membrane integrity of anuran sperm in fresh water for up to 6 hours showed an extremely high osmotic tolerance relative to fish sperm. The very high longevity and osmotic tolerance of anuran sperm and high longevity of cryptobranchid sperm, relative to those of freshwater fish, may reflect the complex fertilization history of amphibian sperm in

  1. Temporal and spatial fate of GFP-expressing motile and nonmotile Aeromonas hydrophila in the house fly digestive tract.

    PubMed

    McGaughey, Joseph; Nayduch, Dana

    2009-01-01

    To gain insight into the transmissibility of bacteria by house flies, the temporal and spatial fate of green fluorescent protein (GFP)-expressing motile and nonmotile strains of Aeromonas hydrophila was examined within the alimentary canal. Liquid food consumed by house flies is first stored in the crop and then is regurgitated and/or passed into the midgut. Once within the midgut, food is contained inside a double-layered peritrophic matrix (PM), with the inner layer enveloping digested material and forming fecal pellets for excretion. Between 1 and 12 h after ingestion, and irrespective of motility, live GFP+ A. hydrophila adhered to the luminal surfaces of the crop and inner PM of bacteria-fed flies. However, some nonadherent, motile bacteria moved freely within the PM lumen in the anteromedial midgut, whereas fecal pellets (lysed bacteria) continued passing posteriorly. At 12-24 h, adhered bacteria of both strains were lysed in the distal midgut, compressed into fecal pellets, and excreted. Viable bacteria in the crop visually exceeded numbers within these fecal pellets. Culture recovery at the same time points showed a 1,000-fold increase of viable bacteria at 2 h, presumably in the crop, with a temporal decline thereafter. Further, viable bacteria were recovered from vomit specks and orally contaminated substrates up to 2 h after feeding but never from feces. These results suggest that A. hydrophila is a transient resident of the house fly alimentary canal and is only orally transmissible for a short time after ingestion. Thus, regurgitation may be more significant than fecal transmission in the spread of some house fly transmitted bacterial diseases.

  2. Proteomic analysis of Campylobacter jejuni 11168 biofilms reveals a role for the motility complex in biofilm formation.

    PubMed

    Kalmokoff, Martin; Lanthier, Patricia; Tremblay, Tammy-Lynn; Foss, Mary; Lau, Peter C; Sanders, Greg; Austin, John; Kelly, John; Szymanski, Christine M

    2006-06-01

    Campylobacter jejuni remains the leading cause of bacterial gastroenteritis in developed countries, and yet little is known concerning the mechanisms by which this fastidious organism survives within its environment. We have demonstrated that C. jejuni 11168 can form biofilms on a variety of surfaces. Proteomic analyses of planktonic and biofilm-grown cells demonstrated differences in protein expression profiles between the two growth modes. Proteins involved in the motility complex, including the flagellins (FlaA, FlaB), the filament cap (FliD), the basal body (FlgG, FlgG2), and the chemotactic protein (CheA), all exhibited higher levels of expression in biofilms than found in stationary-phase planktonic cells. Additional proteins with enhanced expression included those involved in the general (GroEL, GroES) and oxidative (Tpx, Ahp) stress responses, two known adhesins (Peb1, FlaC), and proteins involved in biosynthesis, energy generation, and catabolic functions. An aflagellate flhA mutant not only lost the ability to attach to a solid matrix and form a biofilm but could no longer form a pellicle at the air-liquid interface of a liquid culture. Insertional inactivation of genes that affect the flagellar filament (fliA, flaA, flaB, flaG) or the expression of the cell adhesin (flaC) also resulted in a delay in pellicle formation. These findings demonstrate that the flagellar motility complex plays a crucial role in the initial attachment of C. jejuni 11168 to solid surfaces during biofilm formation as well as in the cell-to-cell interactions required for pellicle formation. Continued expression of the motility complex in mature biofilms is unusual and suggests a role for the flagellar apparatus in the biofilm phenotype.

  3. Role of Proteins of the Ena/VASP Family in Actin-based Motility of Listeria monocytogenes

    PubMed Central

    Laurent, Valérie; Loisel, Thomas P.; Harbeck, Birgit; Wehman, Ann; Gröbe, Lothar; Jockusch, Brigitte M.; Wehland, Jürgen; Gertler, Frank B.; Carlier, Marie-France

    1999-01-01

    Intracellular propulsion of Listeria monocytogenes is the best understood form of motility dependent on actin polymerization. We have used in vitro motility assays of Listeria in platelet and brain extracts to elucidate the function of the focal adhesion proteins of the Ena (Drosophila Enabled)/VASP (vasodilator-stimulated phosphoprotein) family in actin-based motility. Immunodepletion of VASP from platelet extracts and of Evl (Ena/VASP-like protein) from brain extracts of Mena knockout (−/−) mice combined with add-back of recombinant (bacterial or eukaryotic) VASP and Evl show that VASP, Mena, and Evl play interchangeable roles and are required to transform actin polymerization into active movement and propulsive force. The EVH1 (Ena/VASP homology 1) domain of VASP is in slow association–dissociation equilibrium high-affinity binding to the zyxin-homologous, proline-rich region of ActA. VASP also interacts with F-actin via its COOH-terminal EVH2 domain. Hence VASP/ Ena/Evl link the bacterium to the actin tail, which is required for movement. The affinity of VASP for F-actin is controlled by phosphorylation of serine 157 by cAMP-dependent protein kinase. Phospho-VASP binds with high affinity (0.5 × 108 M−1); dephospho-VASP binds 40-fold less tightly. We propose a molecular ratchet model for insertional polymerization of actin, within which frequent attachment–detachment of VASP to F-actin allows its sliding along the growing filament. PMID:10087267

  4. Pseudomonas aeruginosa serA Gene Is Required for Bacterial Translocation through Caco-2 Cell Monolayers.

    PubMed

    Yasuda, Masashi; Nagata, Syouya; Yamane, Satoshi; Kunikata, Chinami; Kida, Yutaka; Kuwano, Koichi; Suezawa, Chigusa; Okuda, Jun

    2017-01-01

    To specify critical factors responsible for Pseudomonas aeruginosa penetration through the Caco-2 cell epithelial barrier, we analyzed transposon insertion mutants that demonstrated a dramatic reduction in penetration activity relative to P. aeruginosa PAO1 strain. From these strains, mutations could be grouped into five classes, specifically flagellin-associated genes, pili-associated genes, heat-shock protein genes, genes related to the glycolytic pathway, and biosynthesis-related genes. Of these mutants, we here focused on the serA mutant, as the association between this gene and penetration activity is yet unknown. Inactivation of the serA gene caused significant repression of bacterial penetration through Caco-2 cell monolayers with decreased swimming and swarming motilities, bacterial adherence, and fly mortality rate, as well as repression of ExoS secretion; however, twitching motility was not affected. Furthermore, L-serine, which is known to inhibit the D-3-phosphoglycerate dehydrogenase activity of the SerA protein, caused significant reductions in penetration through Caco-2 cell monolayers, swarming and swimming motilities, bacterial adherence to Caco-2 cells, and virulence in flies in the wild-type P. aeruginosa PAO1 strain. Together, these results suggest that serA is associated with bacterial motility and adherence, which are mediated by flagella that play a key role in the penetration of P. aeruginosa through Caco-2 cell monolayers. Oral administration of L-serine to compromised hosts might have the potential to interfere with bacterial translocation and prevent septicemia caused by P. aeruginosa through inhibition of serA function.

  5. Pseudomonas aeruginosa serA Gene Is Required for Bacterial Translocation through Caco-2 Cell Monolayers

    PubMed Central

    Yasuda, Masashi; Nagata, Syouya; Yamane, Satoshi; Kunikata, Chinami; Kida, Yutaka; Kuwano, Koichi; Suezawa, Chigusa; Okuda, Jun

    2017-01-01

    To specify critical factors responsible for Pseudomonas aeruginosa penetration through the Caco-2 cell epithelial barrier, we analyzed transposon insertion mutants that demonstrated a dramatic reduction in penetration activity relative to P. aeruginosa PAO1 strain. From these strains, mutations could be grouped into five classes, specifically flagellin-associated genes, pili-associated genes, heat-shock protein genes, genes related to the glycolytic pathway, and biosynthesis-related genes. Of these mutants, we here focused on the serA mutant, as the association between this gene and penetration activity is yet unknown. Inactivation of the serA gene caused significant repression of bacterial penetration through Caco-2 cell monolayers with decreased swimming and swarming motilities, bacterial adherence, and fly mortality rate, as well as repression of ExoS secretion; however, twitching motility was not affected. Furthermore, L-serine, which is known to inhibit the D-3-phosphoglycerate dehydrogenase activity of the SerA protein, caused significant reductions in penetration through Caco-2 cell monolayers, swarming and swimming motilities, bacterial adherence to Caco-2 cells, and virulence in flies in the wild-type P. aeruginosa PAO1 strain. Together, these results suggest that serA is associated with bacterial motility and adherence, which are mediated by flagella that play a key role in the penetration of P. aeruginosa through Caco-2 cell monolayers. Oral administration of L-serine to compromised hosts might have the potential to interfere with bacterial translocation and prevent septicemia caused by P. aeruginosa through inhibition of serA function. PMID:28046014

  6. Two Residues Predominantly Dictate Functional Difference in Motility between Shewanella oneidensis Flagellins FlaA and FlaB*

    PubMed Central

    Sun, Linlin; Dong, Yangyang; Shi, Miaomiao; Jin, Miao; Zhou, Qing; Luo, Zhao-Qing; Gao, Haichun

    2014-01-01

    Nearly half of flagellated microorganisms possess a multiple-flagellin system. Although a functional filament can be formed from one of multiple flagellins alone in many bacteria, it is more common that one flagellin is the major constituent and others contribute. Underlying mechanisms proposed for such scenarios cover flagellin regulation of various levels, including transcription, translation, post-translational modification, secretion, and filament assembly. In Shewanella oneidensis, the flagellar filament is composed of FlaA and FlaB flagellins; the latter is the major one in terms of motility. In this study, we showed that regulation of all levels except for filament assembly is indistinguishable between these two flagellins. Further analyses revealed that two amino acid residues predominantly dictated functional difference with respect to motility. Given that Shewanella prefer a solid surface-associated life style, of which filaments consisting of either FlaA or FlaB are equally supportive, we envision that roles of flagella in surface adhesion and formation of bacterial communities are particularly important for their survival and proliferation in these specific niches. PMID:24733391

  7. [On the significance of Solcoseryl on fertility. 1. The effect of Solcoseryl on sperm motility in vitro].

    PubMed

    Mattheus, A; Heise, H; Hofmann, R

    1980-01-01

    The effect of different Solcoseryl (Solco, Basel, Switzerland) concentrations on the motility of human sperm were tested on 37 ejaculates taken from two subject groups. Altogether 111 motility studies were performed using the eosine vitality test. In view of the considerable variations associated with motility tests, Solcoseryl appeared to have no effect on sperm motility in the majority of cases in group 1. The observed improvement in motility (20%) was countered by still greater motility losses (27%). The results, obtained by studies on selected asthenospermia (group 2) are different, however: the 26% increase in motility was opposed to a motility loss of only 17%. A Solcoseryl concentration of 50% was found to have the best effects on motility. A general rise in sperm motility by means of Solcoseryl cannot be considered, although tests would appear advisable in isolated instances. Solcoseryl may be a valuable protective resuspension agent for insemination purposes.

  8. Effects of environment factors on initiation of sperm motility in sea cucumber Apostichopus japonicus (Selenka)

    NASA Astrophysics Data System (ADS)

    Yu, Li; Shao, Mingyu; Bao, Zhenmin; Hu, Jingjie; Zhang, Zhifeng

    2011-06-01

    Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 mOsm kg-1. The sperm started to be motile as a result of increased osmolality, indicating an osmolality-dependent initiation of sperm motility in sea cucumber. After a brief incubation in hypotonic NaCl and glucose solutions with osmolalities of 200 and 400 mOsm kg-1, sperm lost partial motile ability. Sperm became immobilized when pH was 6.0 in NaCl, glucose and mannitol solutions, suggesting that an H+ release is involved in sperm activation. The decreased pH had no effect on the percentage of motile sperm in ASW, whereas it delayed the time period to reach the maximum motility (motilitymax). Extracellular Ca2+ in electrolyte solutions was not essential for motility stimulation but shortened the time of reaching motilitymax. When Ca2+ was mixed in nonelectrolyte solutions the sperm motility was completely suppressed. The K+ channel blocker, quinine, suppressed the sperm motility in electrolyte solution, showing a possible involvement of K+ transport in the process. High K+ concentration did not affect the sperm motility in NaCl solution, but decreased it in ASW and almost entirely suppressed it in nonelectrolyte solutions. The different effects of pH and K+ in ASW and NaCl solution indicate that external ions may also regulate sperm motility.

  9. The role of calcium and Ca2+-ATPase in maintaining motility in ram spermatozoa.

    PubMed

    Breitbart, H; Rubinstein, S; Nass-Arden, L

    1985-09-25

    Extracellular calcium at millimolar concentrations inhibits collective motility of ejaculated ram spermatozoa. In untreated cells, or when motility was made dependent upon glycolytic activity, there is very small inhibition, but when motility was made dependent upon mitochondrial respiration there is very high inhibition in motility by increasing extracellular Ca2+ concentration. Quercetin, which inhibits (Ca2+ + Mg2+)-ATPase activity in isolated plasma membranes, also inhibits motility mainly in cells that have been made dependent upon glycolytic activity, but there is also inhibition in untreated cells. When motility was made dependent upon mitochondrial activity, there is no inhibition but rather some stimulation in motility by quercetin. The inhibitory effect of quercetin is enhanced by increasing Ca2+ concentration in the medium. Quercetin also inhibits uptake of calcium into the cells, in a mechanism by which a calcium channel is involved. This inhibition is high only when the glycolysis is inhibited in the cells. The rate of glycolysis is decreased by quercetin or ouabain, but their effects on motility are quite different. Based on these data, it appears that the plasma membrane (Ca2+ + Mg2+)-ATPase or the Ca2+ pump have a functional role in the regulation of spermatozoa motility. This motility regulation is functioning through mechanisms which include glycolytic activity and maintenance of intracellular calcium concentrations.

  10. Single-gene tuning of Caulobacter cell cycle period and noise, swarming motility, and surface adhesion

    PubMed Central

    Lin, Yihan; Crosson, Sean; Scherer, Norbert F

    2010-01-01

    Sensor histidine kinases underlie the regulation of a range of physiological processes in bacterial cells, from chemotaxis to cell division. In the gram-negative bacterium Caulobacter crescentus, the membrane-bound histidine kinase, DivJ, is a polar-localized regulator of cell cycle progression and development. We show that DivJ localizes to the cell pole through a dynamic diffusion and capture mechanism rather than by active localization. Analysis of single C. crescentus cells in microfluidic culture demonstrates that controlled expression of divJ permits facile tuning of both the mean and noise of the cell division period. Simulations of the cell cycle that use a simplified protein interaction network capture previously measured oscillatory protein profiles, and recapitulate the experimental observation that deletion of divJ increases the cell cycle period and noise. We further demonstrate that surface adhesion and swarming motility of C. crescentus in semi-solid media can also be tuned by divJ expression. We propose a model in which pleiotropic control of polar cell development by the DivJ–DivK–PleC signaling pathway underlies divJ-dependent tuning of cell swarming and adhesion behaviors. PMID:21179017

  11. Flow visualization study on the near-surface motility of a flagellar propeller

    NASA Astrophysics Data System (ADS)

    Yim, Dongwook; Cho, Jaehyeong; Jin, Songwan; Yoo, Jung Yul

    2012-11-01

    Understanding of the near-surface motility of microorganisms is important in many bioengineering applications including the initial formation of biofilms and energy-efficient propulsion system which is the most important part of microrobots. In particular, a new type of propeller that is optimized for low Reynolds numbers is required to propel a small object in a medium where the flow is dominated by viscous force rather than inertial force. A propeller in the shape of a bacterial flagellum seems an appropriate choice for this purpose. Thus, in this study, we carried out a flow visualization study on the velocity field near the solid surface, induced by a spring-like propeller inspired by the E. coli flagellum, by using a macroscopic model and applying stereoscopic particle image velocimetry. Silicone oil, which has a kinematic viscosity 100,000 times that of water, was used as the working fluid to generate the low Reynolds number condition for the macroscopic model. Thrust, torque, and velocity were measured as functions of pitch and rotational speed, and the efficiency of the propeller was calculated from the measured results. The supports of the Basic Science Research Program (2009-0071117) and also by the Priority Research Centers Program (2011-0029613) through the NRF funded by the MEST, Republic of Korea are gratefully acknowledged.

  12. Interplay between inflammation, immune system and neuronal pathways: effect on gastrointestinal motility.

    PubMed

    De Winter, Benedicte-Y; De Man, Joris-G

    2010-11-28

    Sepsis is a systemic inflammatory response representing the leading cause of death in critically ill patients, mostly due to multiple organ failure. The gastrointestinal tract plays a pivotal role in the pathogenesis of sepsis-induced multiple organ failure through intestinal barrier dysfunction, bacterial translocation and ileus. In this review we address the role of the gastrointestinal tract, the mediators, cell types and transduction pathways involved, based on experimental data obtained from models of inflammation-induced ileus and (preliminary) clinical data. The complex interplay within the gastrointestinal wall between mast cells, residential macrophages and glial cells on the one hand, and neurons and smooth muscle cells on the other hand, involves intracellular signaling pathways, Toll-like receptors and a plethora of neuroactive substances such as nitric oxide, prostaglandins, cytokines, chemokines, growth factors, tryptases and hormones. Multidirectional signaling between the different components in the gastrointestinal wall, the spinal cord and central nervous system impacts inflammation and its consequences. We propose that novel therapeutic strategies should target inflammation on the one hand and gastrointestinal motility, gastrointestinal sensitivity and even pain signaling on the other hand, for instance by impeding afferent neuronal signaling, by activation of the vagal anti-inflammatory pathway or by the use of pharmacological agents such as ghrelin and ghrelin agonists or drugs interfering with the endocannabinoid system.

  13. Repression of common bull sperm flora and in vitro impairment of sperm motility with Pseudomonas aeruginosa introduced by contaminated lubricant.

    PubMed

    Smole, I; Thomann, A; Frey, J; Perreten, V

    2010-08-01

    Semen collected from clinically healthy bulls at an artificial insemination centre was examined for bacterial diversity. While bacteria that are normally present in the common flora of bovine semen were absent, such as Mycoplasma sp., Proteus sp. and Corynebacterium sp., all semen samples contained an unusually high number of Pseudomonas aeruginosa strains. Analysis via pulsed field gel electrophoresis demonstrated that one particular P. aeruginosa strain, present in a sealed bottle of lubricant, was widespread in bull semen. This strain was shown to secrete substances that inhibited both the growth of bacteria constituting the normal bull sperm flora and the motility of spermatozoa in vitro. This study demonstrated that commercially available lubricants might contain bacteria that can spread amongst breeding bulls and affect the quality of semen. Bacteriological controls and species' identification are necessary at several production levels, including lubricants and extenders, to ensure high semen quality and avoid the spread of pathogens.

  14. Thiosulfate as a metabolic product: the bacterial fermentation of taurine.

    PubMed

    Denger, K; Laue, H; Cook, A M

    1997-10-01

    Thiosulfate (S2O32-) is a natural product that is widely utilized in natural ecosystems as an electron sink or as an electron donor. However, the major biological source(s) of this thiosulfate is unknown. We present the first report that taurine (2-aminoethanesulfonate), the major mammalian solute, is subject to fermentation. This bacterial fermentation was found to be catalyzed by a new isolate, strain GKNTAU, a strictly anaerobic, gram-positive, motile rod that formed subterminal spores. Thiosulfate was a quantitative fermentation product. The other fermentation products were ammonia and acetate, and all could be formed by cell-free extracts.

  15. Effects of Lizhong Tang on gastrointestinal motility in mice

    PubMed Central

    Lee, Min Cheol; Ha, Wooram; Park, Jinhyeong; Kim, Junghoon; Jung, Yunjin; Kim, Byung Joo

    2016-01-01

    AIM To investigate the effects of Lizhong Tang, a traditional Chinese medicine formula, on gastrointestinal motility in mice. METHODS The in vivo effects of Lizhong Tang on GI motility were investigated by measuring the intestinal transit rates (ITRs) and gastric emptying (GE) values in normal mice and in mice with experimentally induced GI motility dysfunction (GMD). RESULTS In normal ICR mice, the ITR and GE values were significantly and dose-dependently increased by Lizhong Tang (ITR values: 54.4% ± 1.9% vs 65.2% ± 1.8%, P < 0.01 with 0.1 g/kg Lizhong Tang and 54.4% ± 1.9% vs 83.8% ± 1.9%, P < 0.01 with 1 g/kg Lizhong Tang; GE values: 60.7% ± 1.9% vs 66.8% ± 2.1%, P < 0.05 with 0.1 g/kg Lizhong Tang and 60.7% ± 1.9% vs 72.5% ± 1.7%, P < 0.01 with 1 g/kg Lizhong Tang). The ITRs of the GMD mice were significantly reduced compared with those of the normal mice, which were significantly and dose-dependently reversed by Lizhong Tang. Additionally, in loperamide- and cisplatin-induced models of GE delay, Lizhong Tang administration reversed the GE deficits. CONCLUSION These results suggest that Lizhong Tang may be a novel candidate for development as a prokinetic treatment for the GI tract. PMID:27678361

  16. The enigma of eugregarine epicytic folds: where gliding motility originates?

    PubMed Central

    2013-01-01

    Background In the past decades, many studies focused on the cell motility of apicomplexan invasive stages as they represent a potential target for chemotherapeutic intervention. Gregarines (Conoidasida, Gregarinasina) are a heterogeneous group that parasitize invertebrates and urochordates, and are thought to be an early branching lineage of Apicomplexa. As characteristic of apicomplexan zoites, gregarines are covered by a complicated pellicle, consisting of the plasma membrane and the closely apposed inner membrane complex, which is associated with a number of cytoskeletal elements. The cell cortex of eugregarines, the epicyte, is more complicated than that of other apicomplexans, as it forms various superficial structures. Results The epicyte of the eugregarines, Gregarina cuneata, G. polymorpha and G. steini, analysed in the present study is organised in longitudinal folds covering the entire cell. In mature trophozoites and gamonts, each epicytic fold exhibits similar ectoplasmic structures and is built up from the plasma membrane, inner membrane complex, 12-nm filaments, rippled dense structures and basal lamina. In addition, rib-like myonemes and an ectoplasmic network are frequently observed. Under experimental conditions, eugregarines showed varied speeds and paths of simple linear gliding. In all three species, actin and myosin were associated with the pellicle, and this actomyosin complex appeared to be restricted to the lateral parts of the epicytic folds. Treatment of living gamonts with jasplakinolide and cytochalasin D confirmed that actin actively participates in gregarine gliding. Contributions to gliding of specific subcellular components are discussed. Conclusions Cell motility in gregarines and other apicomplexans share features in common, i.e. a three-layered pellicle, an actomyosin complex, and the polymerisation of actin during gliding. Although the general architecture and supramolecular organisation of the pellicle is not correlated with

  17. Extending the molecular clutch beyond actin-based cell motility

    NASA Astrophysics Data System (ADS)

    Havrylenko, Svitlana; Mezanges, Xavier; Batchelder, Ellen; Plastino, Julie

    2014-10-01

    Many cell movements occur via polymerization of the actin cytoskeleton beneath the plasma membrane at the front of the cell, forming a protrusion called a lamellipodium, while myosin contraction squeezes forward the back of the cell. In what is known as the ‘molecular clutch’ description of cell motility, forward movement results from the engagement of the acto-myosin motor with cell-matrix adhesions, thus transmitting force to the substrate and producing movement. However during cell translocation, clutch engagement is not perfect, and as a result, the cytoskeleton slips with respect to the substrate, undergoing backward (retrograde) flow in the direction of the cell body. Retrograde flow is therefore inversely proportional to cell speed and depends on adhesion and acto-myosin dynamics. Here we asked whether the molecular clutch was a general mechanism by measuring motility and retrograde flow for the Caenorhabditis elegans sperm cell in different adhesive conditions. These cells move by adhering to the substrate and emitting a dynamic lamellipodium, but the sperm cell does not contain an acto-myosin cytoskeleton. Instead the lamellipodium is formed by the assembly of major sperm protein, which has no biochemical or structural similarity to actin. We find that these cells display the same molecular clutch characteristics as acto-myosin containing cells. We further show that retrograde flow is produced both by cytoskeletal assembly and contractility in these cells. Overall this study shows that the molecular clutch hypothesis of how polymerization is transduced into motility via adhesions is a general description of cell movement regardless of the composition of the cytoskeleton.

  18. Multiple-exposure photographic analysis of a motile spirochete.

    PubMed Central

    Goldstein, S F; Charon, N W

    1990-01-01

    The Leptospiraceae are thin spirochetes with a unique mode of motility. These spiral-shaped bacteria have internal periplasmic flagella that propel the cells in low-viscosity and gel-like high-viscosity media. A model of Leptospiraceae motility has been previously proposed that states that the subterminally attached periplasmic flagella rotate between the outer sheath and the helical protoplasmic cylinder. The shape of the cell ends and the direction of gyration of these ends are determined by the direction of rotation of the internal periplasmic flagella. Rotation of the periplasmic flagella in one direction causes that end to be spiral-shaped, and rotation in the other direction causes that end to be hook-shaped. One prediction of the model is that these right-handed spirochetes roll clockwise when swimming away from an observer. For maximum swimming efficiency, the model predicts that the sense of the spiral-shaped end is left-handed and gyrates counterclockwise. The present study presents direct evidence that the cell rolls clockwise (protoplasmic cylinder helix diameter = 0.24 micron; pitch = 0.69 micron), the ends gyrate counterclockwise, and the spiral-shaped end is left-handed (helix diameter = 0.6 micron; pitch = 2.7 microns)--as predicted by the model. The hook-shaped end appears approximately planar. The approach used was to illuminate stroboscopically cells slowed by Ficoll and analyze the resultant multiple-exposure photographs focused above and below the axis of the cell. The methodology used should be helpful in analyzing the motility of the larger and more complex spirochetes. Images PMID:2367518

  19. Extending the molecular clutch beyond actin-based cell motility

    PubMed Central

    Havrylenko, Svitlana; Mezanges, Xavier; Batchelder, Ellen; Plastino, Julie

    2014-01-01

    Many cell movements occur via polymerization of the actin cytoskeleton beneath the plasma membrane at the front of the cell, forming a protrusion called a lamellipodium, while myosin contraction squeezes forward the back of the cell. In what is known as the “molecular clutch” description of cell motility, forward movement results from the engagement of the acto-myosin motor with cell-matrix adhesions, thus transmitting force to the substrate and producing movement. However during cell translocation, clutch engagement is not perfect, and as a result, the cytoskeleton slips with respect to the substrate, undergoing backward (retrograde) flow in the direction of the cell body. Retrograde flow is therefore inversely proportional to cell speed and depends on adhesion and acto-myosin dynamics. Here we asked whether the molecular clutch was a general mechanism by measuring motility and retrograde flow for the Caenorhabditis elegans sperm cell in different adhesive conditions. These cells move by adhering to the substrate and emitting a dynamic lamellipodium, but the sperm cell does not contain an acto-myosin cytoskeleton. Instead the lamellipodium is formed by the assembly of Major Sperm Protein (MSP), which has no biochemical or structural similarity to actin. We find that these cells display the same molecular clutch characteristics as acto-myosin containing cells. We further show that retrograde flow is produced both by cytoskeletal assembly and contractility in these cells. Overall this study shows that the molecular clutch hypothesis of how polymerization is transduced into motility via adhesions is a general description of cell movement regardless of the composition of the cytoskeleton. PMID:25383039

  20. Evaluation of antral motility in humans using manometry and scintigraphy.

    PubMed Central

    Jones, K; Edelbroek, M; Horowitz, M; Sun, W M; Dent, J; Roelofs, J; Muecke, T; Akkermans, L

    1995-01-01

    Recent studies suggest that scintigraphy can be used to evaluate non-invasively antral motility in humans, although scintigraphic techniques have not yet been compared with more conventional measurements of intraluminal pressures by manometry. Simultaneous scintigraphic and manometric measurements of antral motility were performed in nine healthy volunteers. After intubation with a sleeve/sidehole catheter which incorporated five pressure sideholes located at 1.5 cm intervals spanning the antrum, each subject ingested 100 g minced beef labelled with 100 MBq 99mTc-chicken liver and 150 ml water. Between 40-43, 60-63, 80-83, and 100-103 minutes after meal ingestion, radioisotopic data were acquired in two second frames. Time-activity curves showing antral 'contractions' resulting from wall motion were derived by drawing small regions of interest over the antrum to coincide with the position of the antral manometric sideholes. Scintigraphic contraction rates approximated 3/minute, whereas antral pressure waves that occluded the lumen were less frequent (p < 0.01 for all), particularly in the proximal antrum. The amplitude of wall motion, evaluated scintigraphically, and the amplitude of pressure waves were both inversely related to the distance from the pylorus (r > -0.32, p < 0.05) and antral volume r > -0.29 (p < 0.05). There were significant relationships between the amplitude of contractions assessed scintigraphically and the number of lumen-occlusive antral pressure waves in the distal antrum (r -0.48, p < 0.05) but not in the more proximal antral regions. It is concluded that scintigraphy can detect antral wall motion with greater sensitivity than manometry, particularly in the proximal antrum. As manometry gives information on the amplitude as well as the temporal and spatial organisation of those contractions which result in lumen occlusion, the combination of scintigraphic and manometric techniques in the evaluation of antral motility shows considerable

  1. Altered motility causes the early gastrointestinal toxicity of irradiation

    SciTech Connect

    Erickson, B.A.; Moulder, J.E.; Otterson, M.F.; Sarna, S.K. )

    1994-03-01

    This article reviews studies of large and small intestinal contractile activity following radiation exposure. Studies of motility utilize strain gauge transducers surgically implanted on the seromuscular layer of the small intestine. All studies were performed in mixed breed dogs to record the occurrence of normal contractions, giant migrating contractions (GMCs) and retrograde giant contractions (RGCs) before, during and after irradiation (22.5 Gy in 9 fractions at 3 fractions/week). Giant migrating contractions and retrograde giant contractions are infrequent in the healthy state. However, in diseased states, GMCs are associated with abdominal cramps and diarrhea, and RGCs precede vomiting. In fasted animals, fractionated abdominal irradiation dramatically increased the frequency of GMCs, with the incidence peaking after the second dose. The increased frequency of GMCS occurred as early as a few hours after the first radiation fraction, and returned to normal within days of cessation of radiation. RGCs were also significantly increased after abdominal irradiation. The frequency of RGCs was greatest on the first and sixth dose of radiation. Clinically, the dogs developed nausea, vomiting and diarrhea as early as the first day of irradiation. In dogs studied in the fed state, decreased amplitude, duration, and frequency of postprandial contractions occurred. These changes may slow intestinal transit during irradiation. Radiation also produced a striking increase in the frequency of colonic GMCs; these changes in colonic motor activity were associated with diarrhea as early as the second irradiation. Changes in GI motility during fractionated irradiation precede the appearance of histopathological lesions in the GI tract. Thus, the symptoms of nausea, vomiting, and diarrhea experienced during radiotherapy (particularly those within the first week) are directly related to changes in bowel motility. 41 refs., 7 figs., 1 tab.

  2. Viscumins functionally modulate cell motility-associated gene expression.

    PubMed

    Schötterl, Sonja; Hübner, Miriam; Armento, Angela; Veninga, Vivien; Wirsik, Naita Maren; Bernatz, Simon; Lentzen, Hans; Mittelbronn, Michel; Naumann, Ulrike

    2017-02-01

    In Europe extracts from Viscum album L., the European white-berry mistletoe, are widely used as a complementary cancer therapy. Viscumins (mistletoe lectins, ML) have been scrutinized as important active components of mistletoe and exhibit a variety of anticancer effects such as stimulation of the immune system, induction of cytotoxicity, reduction of tumor cell motility as well as changes in the expression of genes associated with cancer development and progression. By microarray expression analysis, quantitative RT-PCR and RT-PCR based validation of microarray data we demonstrate for the Viscum album extract Iscador Qu and for the lectins Aviscumine and ML-1 that in glioma cells these drugs differentially modulate the expression of genes involved in the regulation of cell migration and invasion, including processes modulating cell architecture and cell adhesion. A variety of differentially expressed genes in ML treated cells are associated with the transforming growth factor (TGF)-β signaling pathway or are targets of TGF-β. ML treatment downregulated the expression of TGF-β itself, of the TGF-β receptor II (TGFBR2), of the TGF-β intracellular signal transducer protein SMAD2, and of matrix-metalloproteinases (MMP) MMP-2 and MMP-14. Even if the changes in gene expression differ between Aviscumine, Iscador Qu and ML-1, the overall regulation of motility associated gene expression by all drugs showed functional effects since tumor cell motility was reduced in a ML-dependent manner. Therefore, ML containing compounds might provide clinical benefit as adjuvant therapeutics in the treatment of patients with invasively growing tumors such as glioblastomas.

  3. Gastrointestinal Motility, Part 2: Small-Bowel and Colon Transit.

    PubMed

    Maurer, Alan H

    2016-03-01

    Because of the difficulty often encountered in deciding whether a patient's symptoms originate in the upper or lower gastrointestinal tract, gastrointestinal transit scintigraphy is a uniquely suited noninvasive, quantitative, and physiologic method of determining whether there is a motility disorder affecting the stomach, small bowel, or colon. Small-bowel and colon transit studies can be performed alone or together with gastric emptying studies after oral administration of an appropriately radiolabeled meal. It is hoped that newly published standards for performing these studies and the anticipated arrival of new Current Procedural Terminology codes in the United States for small-bowel and colon transit studies will increase their availability and use.

  4. Gastrointestinal Motility, Part 2: Small-Bowel and Colon Transit.

    PubMed

    Maurer, Alan H

    2015-09-01

    Because of the difficulty often encountered in deciding whether a patient's symptoms originate in the upper or lower gastrointestinal tract, gastrointestinal transit scintigraphy is a uniquely suited noninvasive, quantitative, and physiologic method of determining whether there is a motility disorder affecting the stomach, small bowel, or colon. Small-bowel and colon transit studies can be performed alone or together with gastric emptying studies after oral administration of an appropriately radiolabeled meal. It is hoped that newly published standards for performing these studies and the anticipated arrival of new Current Procedural Terminology codes in the United States for small-bowel and colon transit studies will increase their availability and use.

  5. Cancer cell motility: lessons from migration in confined spaces

    PubMed Central

    Paul, Colin D.; Mistriotis, Panagiotis; Konstantopoulos, Konstantinos

    2017-01-01

    Time-lapse, deep-tissue imaging made possible by advances in intravital microscopy has demonstrated the importance of tumour cell migration through confining tracks in vivo. These tracks may either be endogenous features of tissues or be created by tumour or tumour-associated cells. Importantly, migration mechanisms through confining microenvironments are not predicted by 2D migration assays. Engineered in vitro models have been used to delineate the mechanisms of cell motility through confining spaces encountered in vivo. Understanding cancer cell locomotion through physiologically relevant confining tracks could be useful in developing therapeutic strategies to combat metastasis. PMID:27909339

  6. Cancer cell motility: lessons from migration in confined spaces.

    PubMed

    Paul, Colin D; Mistriotis, Panagiotis; Konstantopoulos, Konstantinos

    2017-02-01

    Time-lapse, deep-tissue imaging made possible by advances in intravital microscopy has demonstrated the importance of tumour cell migration through confining tracks in vivo. These tracks may either be endogenous features of tissues or be created by tumour or tumour-associated cells. Importantly, migration mechanisms through confining microenvironments are not predicted by 2D migration assays. Engineered in vitro models have been used to delineate the mechanisms of cell motility through confining spaces encountered in vivo. Understanding cancer cell locomotion through physiologically relevant confining tracks could be useful in developing therapeutic strategies to combat metastasis.

  7. The gastrointestinal pharmacology of cannabinoids: focus on motility.

    PubMed

    Abalo, Raquel; Vera, Gema; López-Pérez, Ana Esther; Martínez-Villaluenga, María; Martín-Fontelles, María Isabel

    2012-01-01

    The marijuana plant Cannabis sp. and its derivatives and analogues, known as cannabinoids (CBs), induce many effects throughout the whole body. Herein we briefly review the gastrointestinal (GI) pharmacology of CBs, with special focus on motor function. Some drugs are available to treat nausea and emesis, and evidences in humans and animal models suggest that other GI motility alterations (gastro-oesophageal reflux, inflammatory bowel conditions or paralytic ileus) might benefit from modifications of the CB tone throughout the gut. However, central and peripheral (including GI) side effects may occur upon acute and chronic CB administration. Hopefully, the ongoing worldwide intense research on CBs will soon provide new, safer CB-based medicines.

  8. Traveling waves in actin dynamics and cell motility

    PubMed Central

    Allard, Jun; Mogilner, Alex

    2012-01-01

    Much of current understanding of cell motility arose from studying steady treadmilling of actin arrays. Recently, there have been a growing number of observations of a more complex, non-steady, actin behavior, including self-organized waves. It is becoming clear that these waves result from activation and inhibition feedbacks in actin dynamics acting on different scales, but the exact molecular nature of these feedbacks and respective roles of biomechanics and biochemistry are still unclear. Here, we review recent advances achieved in experimental and theoretical studies of actin waves and discuss mechanisms and physiological significance of wavy protrusions. PMID:22985541

  9. [Treatment of postoperative impairment of gastrointestinal motility, cholangitis and pancreatitis].

    PubMed

    Schulze, T; Heidecke, C-D

    2015-06-01

    Although the mortality associated with major hepatopancreaticobiliary surgery has continuously decreased during the last decades, the morbidity of these procedures remains high. Functional disturbances of normal gastrointestinal motility as well as inflammation and infections of surgically treated organs are frequent complications resulting in considerably prolonged lengths of stay in hospital and increased healthcare costs. This review article highlights the therapeutic approaches and recent developments in the treatment of delayed gastric emptying, prolonged postoperative ileus, postoperative cholangitis and pancreatitis after hepatopancreaticobiliary surgery. Current practice is discussed on the basis of recent results in basic and clinical research, review articles, meta-analyses and guidelines.

  10. Reversible expression of motility and flagella in Clostridium chauvoei and their relationship to virulence.

    PubMed

    Tamura, Y; Kijima-Tanaka, M; Aoki, A; Ogikubo, Y; Takahashi, T

    1995-03-01

    Clostridium chauvoei strain Okinawa produced spontaneous non-motile variants at an unusually high rate (approx. 10(-4) per generation) under normal conditions without mutagen. Revertants of non-motile variants were detected at a rate of approximately 10(-3). Biochemically, every variant corresponded well with the parental strain. By transmission electron microscopy, three of nine non-motile variants of strain Okinawa were found to be flagellate, while the other six were found to be aflagellate. These phenotypes were confirmed by Western blot analysis using monoclonal antibodies directed against the flagella of C. chauvoei. Moreover, the parental flagellate strain and non-motile flagellate variants were significantly more virulent in mice than non-motile, aflagellate variants. Our results demonstrated that phase variation in motility and flagellation occurs in C. chauvoei, and that the flagella are associated with the full expression of virulence.

  11. Cryopreservation of human spermatozoa. III. The effect of cryoprotectants on motility.

    PubMed

    Critser, J K; Huse-Benda, A R; Aaker, D V; Arneson, B W; Ball, G D

    1988-08-01

    A series of experiments was conducted to examine potential toxic effects of cryoprotectants on motility of human spermatozoa. The data indicated that exposure of spermatozoa to cryoprotectant medium for as little as 15 minutes at room temperature caused a reduction in motility. This reduction in motility was caused by glycerol. Lowering glycerol concentrations from 7.5% to 5.0% improved sperm motility at 24 hours post-thaw. Sperm motility was not affected by either slow or abrupt cooling rates above -5 degrees C. Motility was greater in cryopreserved sperm at 24 hours post-thaw when glycerol was added at -5 degrees C rather than at room temperature. These data suggest that avoiding glycerol toxicity either by reducing the concentration used or by adding glycerol at a lower temperature, or both, may improve human sperm cryosurvival rates.

  12. A Role for the EAL-Like Protein STM1344 in Regulation of CsgD Expression and Motility in Salmonella enterica Serovar Typhimurium▿

    PubMed Central

    Simm, Roger; Remminghorst, Uwe; Ahmad, Irfan; Zakikhany, Katherina; Römling, Ute

    2009-01-01

    The bacterial second messenger cyclic di-GMP (c-di-GMP) regulates the transition between sessility and motility. In Salmonella enterica serovar Typhimurium, the expression of CsgD, the regulator of multicellular rdar morphotype behavior, is a major target of c-di-GMP signaling. CsgD expression is positively regulated by at least two diguanylate cyclases, GGDEF domain proteins, and negatively regulated by at least four phosphodiesterases, EAL domain proteins. Here, we show that in contrast to EAL domain proteins acting as phosphodiesterases, the EAL-like protein STM1344 regulated CsgD expression positively and motility negatively. STM1344, however, did not have a role in c-di-GMP turnover and also did not bind the nucleotide. STM1344 acted upstream of the phosphodiesterases STM1703 and STM3611, previously identified to participate in CsgD downregulation, where it repressed their expression. Consequently, although STM1344 has not retained a direct role in c-di-GMP metabolism, it still participates in the regulation of c-di-GMP turnover and has a role in the transition between sessility and motility. PMID:19376870

  13. Lipopolysaccharide-induced α-catenin downregulation enhances the motility of human colorectal cancer cells in an NF-κB signaling-dependent manner

    PubMed Central

    Cheng, Guoping; Yang, Shifeng; Zhang, Gu; Xu, Yanxia; Liu, Xiaoling; Sun, Wenyong; Zhu, Liang

    2016-01-01

    α-Catenin is an important molecule involved in the maintenance of cell–cell adhesion and a prognostic marker in cancer since its expression is essential for preventing cancer metastasis. However, the mechanism that leads to the downregulation of α-catenin in cancer progression remains unclear. The present study revealed that lipopolysaccharide (LPS)-induced NF-κB signaling activation suppressed α-catenin expression and motility in SW620 colorectal cancer (CRC) cells, using real-time polymerase chain reaction, Western blotting, and transwell migration assays. LPS treatment reduced both the mRNA and protein expression of α-catenin and thereby enhanced cell motility. Conversely, incubating cells with an NF-κB inhibitor disrupted these effects. Furthermore, the ectopic expression of p65 alone mimicked the effects of LPS stimulation. In CRC tissues, the presence of enteric bacterial LPS-related neutrophil-enriched foci was correlated with α-catenin downregulation. Collectively, these findings suggest that LPS-induced NF-κB signaling is related to α-catenin suppression and enhanced cell motility in CRC. Therefore, NF-κB is a novel potential therapeutic target for CRC metastasis. PMID:28008274

  14. A phage protein that inhibits the bacterial ATPase required for type IV pilus assembly.

    PubMed

    Chung, In-Young; Jang, Hye-Jeong; Bae, Hee-Won; Cho, You-Hee

    2014-08-05

    Type IV pili (TFPs) are required for bacterial twitching motility and for phage infection in the opportunistic human pathogen Pseudomonas aeruginosa. Here we describe a phage-encoded protein, D3112 protein gp05 (hereafter referred to as Tip, representing twitching inhibitory protein), whose expression is necessary and sufficient to mediate the inhibition of twitching motility. Tip interacts with and blocks the activity of bacterial-encoded PilB, the TFP assembly/extension ATPase, at an internal 40-aa region unique to PilB. Tip expression results in the loss of surface piliation. Based on these observations and the fact that many P. aeruginosa phages require TFPs for infection, Tip-mediated twitching inhibition may represent a generalized strategy for superinfection exclusion. Moreover, because TFPs are required for full virulence, PilB may be an attractive target for the development of novel antiinfectives.

  15. Leukocyte Motility Models Assessed through Simulation and Multi-objective Optimization-Based Model Selection

    PubMed Central

    Bailey, Jacqueline; Timmis, Jon; Chtanova, Tatyana

    2016-01-01

    The advent of two-photon microscopy now reveals unprecedented, detailed spatio-temporal data on cellular motility and interactions in vivo. Understanding cellular motility patterns is key to gaining insight into the development and possible manipulation of the immune response. Computational simulation has become an established technique for understanding immune processes and evaluating hypotheses in the context of experimental data, and there is clear scope to integrate microscopy-informed motility dynamics. However, determining which motility model best reflects in vivo motility is non-trivial: 3D motility is an intricate process requiring several metrics to characterize. This complicates model selection and parameterization, which must be performed against several metrics simultaneously. Here we evaluate Brownian motion, Lévy walk and several correlated random walks (CRWs) against the motility dynamics of neutrophils and lymph node T cells under inflammatory conditions by simultaneously considering cellular translational and turn speeds, and meandering indices. Heterogeneous cells exhibiting a continuum of inherent translational speeds and directionalities comprise both datasets, a feature significantly improving capture of in vivo motility when simulated as a CRW. Furthermore, translational and turn speeds are inversely correlated, and the corresponding CRW simulation again improves capture of our in vivo data, albeit to a lesser extent. In contrast, Brownian motion poorly reflects our data. Lévy walk is competitive in capturing some aspects of neutrophil motility, but T cell directional persistence only, therein highlighting the importance of evaluating models against several motility metrics simultaneously. This we achieve through novel application of multi-objective optimization, wherein each model is independently implemented and then parameterized to identify optimal trade-offs in performance against each metric. The resultant Pareto fronts of optimal

  16. Leukocyte Motility Models Assessed through Simulation and Multi-objective Optimization-Based Model Selection.

    PubMed

    Read, Mark N; Bailey, Jacqueline; Timmis, Jon; Chtanova, Tatyana

    2016-09-01

    The advent of two-photon microscopy now reveals unprecedented, detailed spatio-temporal data on cellular motility and interactions in vivo. Understanding cellular motility patterns is key to gaining insight into the development and possible manipulation of the immune response. Computational simulation has become an established technique for understanding immune processes and evaluating hypotheses in the context of experimental data, and there is clear scope to integrate microscopy-informed motility dynamics. However, determining which motility model best reflects in vivo motility is non-trivial: 3D motility is an intricate process requiring several metrics to characterize. This complicates model selection and parameterization, which must be performed against several metrics simultaneously. Here we evaluate Brownian motion, Lévy walk and several correlated random walks (CRWs) against the motility dynamics of neutrophils and lymph node T cells under inflammatory conditions by simultaneously considering cellular translational and turn speeds, and meandering indices. Heterogeneous cells exhibiting a continuum of inherent translational speeds and directionalities comprise both datasets, a feature significantly improving capture of in vivo motility when simulated as a CRW. Furthermore, translational and turn speeds are inversely correlated, and the corresponding CRW simulation again improves capture of our in vivo data, albeit to a lesser extent. In contrast, Brownian motion poorly reflects our data. Lévy walk is competitive in capturing some aspects of neutrophil motility, but T cell directional persistence only, therein highlighting the importance of evaluating models against several motility metrics simultaneously. This we achieve through novel application of multi-objective optimization, wherein each model is independently implemented and then parameterized to identify optimal trade-offs in performance against each metric. The resultant Pareto fronts of optimal

  17. Sperm motility initiation by egg jelly of the anuran, Discoglossus pictus may be mediated by sperm motility-initiating substance of the internally-fertilizing newt, Cynops pyrrhogaster.

    PubMed

    Takayama-Watanabe, Eriko; Campanella, Chiara; Kubo, Hideo; Watanabe, Akihiko

    2012-11-01

    The egg jelly of Discoglossus pictus contains sperm motility-activating activity, the molecular basis of which has not been studied. Discoglossus pictus sperm initiated motility immediately after immersion in egg-jelly extract, as well as after immersion in hyposmotic solution, which initiates sperm motility in the external fertilization of anuran amphibians. Sequential treatment of the D. pictus sperm with these two solutions revealed the predominant effect of hyposmolality in initiation of motility. The motility initiation induced by jelly extract was suppressed by a monoclonal antibody (mAb) that is specific for the 34 kDa sperm motility-initiating substance (SMIS) in the egg jelly of the newt, Cynops pyrrhogaster. Immunoblotting using the anti-SMIS mAb revealed several antigenic proteins that included major ones with sizes of 18- and 34-kDa in D. pictus jelly extract. Scanning electron microscopic observation revealed that granules of jelly matrix, in which SMIS localizes and which have a critical role in the internal fertilization of C. pyrrhogaster, were not observed near the surface of the D. pictus egg jelly. These results suggest that sperm motility-activating activity in egg jelly of D. pictus may be mediated by SMIS homologous proteins that act through a mechanism that is partially different from that of C. pyrrhogaster.

  18. Bacterial swimmers that infiltrate and take over the biofilm matrix.

    PubMed

    Houry, Ali; Gohar, Michel; Deschamps, Julien; Tischenko, Ekaterina; Aymerich, Stéphane; Gruss, Alexandra; Briandet, Romain

    2012-08-07

    Bacteria grow in either planktonic form or as biofilms, which are attached to either inert or biological surfaces. Both growth forms are highly relevant states in nature and of paramount scientific focus. However, interchanges between bacteria in these two states have been little explored. We discovered that a subpopulation of planktonic bacilli is propelled by flagella to tunnel deep within a biofilm structure. Swimmers create transient pores that increase macromolecular transfer within the biofilm. Irrigation of the biofilm by swimmer bacteria may improve biofilm bacterial fitness by increasing nutrient flow in the matrix. However, we show that the opposite may also occur (i.e., swimmers can exacerbate killing of biofilm bacteria by facilitating penetration of toxic substances from the environment). We combined these observations with the fact that numerous bacteria produce antimicrobial substances in nature. We hypothesized and proved that motile bacilli expressing a bactericide can also kill a heterologous biofilm population, Staphylococcus aureus in this case, and then occupy the newly created space. These findings identify microbial motility as a determinant of the biofilm landscape and add motility to the complement of traits contributing to rapid alterations in biofilm populations.

  19. Two-Dimensional Motility of a Macrophage Cell Line on Microcontact-Printed Fibronectin

    PubMed Central

    Hind, Laurel E.; MacKay, Joanna L.; Cox, Dianne; Hammer, Daniel A.

    2014-01-01

    The ability of macrophages to migrate to sites of infection and inflammation is critical for their role in the innate immune response. Macrophage cell lines have made it possible to study the roles of individual proteins responsible for migration using molecular biology, but it has not been possible to reliably elicit the motility of macrophage cell lines in two-dimensions. In the past, measurements of the motility of macrophage cell lines have been largely limited to transwell assays which provide limited quantitative information on motility and limited ability to visualize cell morphology. We used microcontact printing to create polydimethylsiloxane (PDMS) surfaces functionalized with fibronectin that otherwise support little macrophage adhesion. We used these surfaces to measure macrophage migration in two-dimensions and found that these cells migrate efficiently in a uniform field of colony-stimulating factor-1, CSF-1. Knockdown of Cdc42 led to a non-statistically significant reduction in motility, whereas chemical inhibition of PI3K activity led to a complete loss of motility. Inhibition of the RhoA kinase, ROCK, did not abolish the motility of these cells but caused a quantitative change in motility, reducing motility significantly on high concentrations of fibronectin but not on low concentrations. This study illustrates the importance of studying cell motility on well controlled materials to better understand the exact roles of specific proteins on macrophage migration. PMID:25186818

  20. Relationship between Porcine Sperm Motility and Sperm Enzymatic Activity using Paper-based Devices.

    PubMed

    Matsuura, Koji; Huang, Han-Wei; Chen, Ming-Cheng; Chen, Yu; Cheng, Chao-Min

    2017-04-07

    Mammalian sperm motility has traditionally been analyzed to determine fertility using computer-assisted semen analysis (CASA) systems. To develop low-cost and robust male fertility diagnostics, we created a paper-based MTT assay and used it to estimate motile sperm concentration. When porcine sperm motility was inhibited using sperm enzyme inhibitors for sperm enzymes related to mitochondrial activity and glycolysis, we simultaneously recorded sperm motility and enzymatic reactivity using a portable motility analysis system (iSperm) and a paper-based MTT assay, respectively. When using our paper-based MTT-assay, we calculated the area mean value signal intensity (AMV) to evaluate enzymatic reactivity. Both sperm motility and AMV decreased following treatment with iodoacetamide (IODO) and 3-bromopyruvic acid (3BP), both of which are inhibitors of glycolytic enzymes including glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We found a correlation between recorded motility using iSperm and AMV from our paper-based assay (P < 0.05), suggesting that a sperm-related enzymatic reaction is involved in sperm motility. Under this protocol, MTT reduction was coupled with catalysis of GAPDH and was promoted by electron transfer from NADH. Based on this inhibitor study, sperm motility can be estimated using our paper-based MTT-assay.

  1. Relationship between Porcine Sperm Motility and Sperm Enzymatic Activity using Paper-based Devices

    PubMed Central

    Matsuura, Koji; Huang, Han-Wei; Chen, Ming-Cheng; Chen, Yu; Cheng, Chao-Min

    2017-01-01

    Mammalian sperm motility has traditionally been analyzed to determine fertility using computer-assisted semen analysis (CASA) systems. To develop low-cost and robust male fertility diagnostics, we created a paper-based MTT assay and used it to estimate motile sperm concentration. When porcine sperm motility was inhibited using sperm enzyme inhibitors for sperm enzymes related to mitochondrial activity and glycolysis, we simultaneously recorded sperm motility and enzymatic reactivity using a portable motility analysis system (iSperm) and a paper-based MTT assay, respectively. When using our paper-based MTT-assay, we calculated the area mean value signal intensity (AMV) to evaluate enzymatic reactivity. Both sperm motility and AMV decreased following treatment with iodoacetamide (IODO) and 3-bromopyruvic acid (3BP), both of which are inhibitors of glycolytic enzymes including glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We found a correlation between recorded motility using iSperm and AMV from our paper-based assay (P < 0.05), suggesting that a sperm-related enzymatic reaction is involved in sperm motility. Under this protocol, MTT reduction was coupled with catalysis of GAPDH and was promoted by electron transfer from NADH. Based on this inhibitor study, sperm motility can be estimated using our paper-based MTT-assay. PMID:28387379

  2. Evolutionarily Ancient Association of the FoxJ1 Transcription Factor with the Motile Ciliogenic Program

    PubMed Central

    Ho, Hao Kee; Babu, Deepak; Eitel, Michael; Narasimhan, Vijayashankaranarayanan; Tiku, Varnesh; Westbrook, Jody; Schierwater, Bernd; Roy, Sudipto

    2012-01-01

    It is generally believed that the last eukaryotic common ancestor (LECA) was a unicellular organism with motile cilia. In the vertebrates, the winged-helix transcription factor FoxJ1 functions as the master regulator of motile cilia biogenesis. Despite the antiquity of cilia, their highly conserved structure, and their mechanism of motility, the evolution of the transcriptional program controlling ciliogenesis has remained incompletely understood. In particular, it is presently not known how the generation of motile cilia is programmed outside of the vertebrates, and whether and to what extent the FoxJ1-dependent regulation is conserved. We have performed a survey of numerous eukaryotic genomes and discovered that genes homologous to foxJ1 are restricted only to organisms belonging to the unikont lineage. Using a mis-expression assay, we then obtained evidence of a conserved ability of FoxJ1 proteins from a number of diverse phyletic groups to activate the expression of a host of motile ciliary genes in zebrafish embryos. Conversely, we found that inactivation of a foxJ1 gene in Schmidtea mediterranea, a platyhelminth (flatworm) that utilizes motile cilia for locomotion, led to a profound disruption in the differentiation of motile cilia. Together, all of these findings provide the first evolutionary perspective into the transcriptional control of motile ciliogenesis and allow us to propose a conserved FoxJ1-regulated mechanism for motile cilia biogenesis back to the origin of the metazoans. PMID:23144623

  3. Multicellularity and the Functional Interdependence of Motility and Molecular Transport

    NASA Astrophysics Data System (ADS)

    Solari, C.; Ganguly, S.; Kessler, J. O.; Michod, R.; Goldstein, R. E.

    2006-03-01

    Benefits, costs and requirements accompany the transition from motile totipotent unicellular organisms to multicellular organisms having cells specialized into reproductive (germ) and vegetative (sterile soma) functions such as motility. In flagellated colonial organisms such as the volvocalean green algae, organized beating by the somatic cells' flagella yields propulsion important in phototaxis and chemotaxis. It has not been generally appreciated that for the larger colonies, flagellar stirring of boundary layers and remote transport are fundamental for maintaining a sufficient rate of metabolite turnover, one not attainable by diffusive transport alone. We describe experiments that quantify the role of advective dynamics in enhancing productivity in germ-soma differentiated colonies. First, experiments with suspended deflagellated colonies of Volvox carteri show that forced advection improves productivity. Second, Particle Imaging Velocimetry of fluid motion around colonies reveals flow fields with very large characteristic velocities U extending to length scales comparable to the colony radius R. For a typical metabolite diffusion constant D, the Peclet number Pe=2UR/D 1, indicative of the dominance of advection over diffusion, with striking augmentation at the cell division stage.

  4. Motility proteins and the origin of the nucleus.

    PubMed

    Dolan, Michael F; Melnitsky, Hannah; Margulis, Lynn; Kolnicki, Robin

    2002-11-01

    Hypotheses on the origin of eukaryotic cells must account for the origin of the microtubular cytoskeletal structures (including the mitotic spindle, undulipodium/cilium (so-called flagellum) and other structures underlain by the 9(2)+2 microtubular axoneme) in addition to the membrane-bounded nucleus. Whereas bacteria with membrane-bounded nucleoids have been described, no precedent for mitotic, cytoskeletal, or axonemal microtubular structures are known in prokaryotes. Molecular phylogenetic analyses indicate that the cells of the earliest-branching lineages of eukaryotes contain the karyomastigont cytoskeletal system. These protist cells divide via an extranuclear spindle and a persistent nuclear membrane. We suggest that this association between the centriole/kinetosome axoneme (undulipodium) and the nucleus existed from the earliest stage of eukaryotic cell evolution. We interpret the karyomastigont to be a legacy of the symbiosis between thermoacidophilic archaebacteria and motile eubacteria from which the first eukaryote evolved. Mutually inconsistent hypotheses for the origin of the nucleus are reviewed and sequenced proteins of cell motility are discussed because of their potential value in resolving this problem. A correlation of fossil evidence with modern cell and microbiological studies leads us to the karyomastigont theory of the origin of the nucleus.

  5. Studies on the ovarian motility of small laboratory rodents.

    PubMed

    Gimeno, M F; Gimeno, A L

    1975-01-01

    Guinea pig ovaries were isolated and immersed in Krebs-Ringer bicarbonate solution, gassed with carbogen and added with glucose as the substrate. The experiments were carried out at 37 degrees C and the preparations were subjected to a basal tension of 500 mg. The spontaneous motility (contractile tension and frequency) of guinea pig ovaries obtained in late proestrus was significantly greater than that of the estrus or early proestrus. The influence of oxytocin on ovarian motility was significantly more marked in late proestrus than in estrus or early proestrus. Both the spontaneous and induced mortility of guinea pig ovaries are augmented in the immediate prevoulatory moment. In isolated rat ovaries, the isometric contractile tension and the frequency of contractions increased as the estral cycle progressed. During late proestrus, left ovaries had a contractile activity of greater intensity and frequency than the right ones, whereas during early proestrus the magnitudes were comparable. Oxytocin elicited greater responses in left than right ovaries of the late proestrus, the effect becoming similar in estrus and early proestrus. Rat ovaries obtained immediately before ovulation are specifically sensitized to the influence of oxytocin and not to other smooth muscle stimulants.

  6. We do, therefore we think: time, motility, and consciousness.

    PubMed

    Goodrich, Barbara Gwenn

    2010-01-01

    This article is a philosopher's expanded review of two recent books on neurophysiology: Rodolfo Llinás's I of the Vortex and György Buszáki's Rhythms of the Brain. Researchers such as these are converging on a view of consciousness as originating in motility and as inherently temporal due to the brainwave oscillations that underlay it. Most current discussions of consciousness include implicit philosophical presuppositions inherited from the canon of Plato, Aristotle, Descartes, and Kant, e.g. that consciousness is self-reflective, passive, and timeless. Because of this, Llinás's and Buszáki's insights may not be fully appreciated. Western philosophy, however, also includes what might be described as a counter-tradition--and one that is more compatible with empirical biological science than the usual canon. Heraclitus, Spinoza, Schopenhauer, Nietzsche, and especially the 20th century French philosopher and psychologist, Merleau-Ponty, all anticipated aspects of Llinás's and Buszáki's approaches. Their alternative conceptual vocabularies are useful for strengthening Llinás's and Buszáki's approaches, sketching out a notion of consciousness emerging from motility, and generating new hypotheses for neurophysiological research.

  7. Modelling cell motility and chemotaxis with evolving surface finite elements.

    PubMed

    Elliott, Charles M; Stinner, Björn; Venkataraman, Chandrasekhar

    2012-11-07

    We present a mathematical and a computational framework for the modelling of cell motility. The cell membrane is represented by an evolving surface, with the movement of the cell determined by the interaction of various forces that act normal to the surface. We consider external forces such as those that may arise owing to inhomogeneities in the medium and a pressure that constrains the enclosed volume, as well as internal forces that arise from the reaction of the cells' surface to stretching and bending. We also consider a protrusive force associated with a reaction-diffusion system (RDS) posed on the cell membrane, with cell polarization modelled by this surface RDS. The computational method is based on an evolving surface finite-element method. The general method can account for the large deformations that arise in cell motility and allows the simulation of cell migration in three dimensions. We illustrate applications of the proposed modelling framework and numerical method by reporting on numerical simulations of a model for eukaryotic chemotaxis and a model for the persistent movement of keratocytes in two and three space dimensions. Movies of the simulated cells can be obtained from http://homepages.warwick.ac.uk/∼maskae/CV_Warwick/Chemotaxis.html.

  8. A Major Determinant for Gliding Motility in Mycoplasma genitalium

    PubMed Central

    Martinelli, Luca; Lalli, Daniela; García-Morales, Luis; Ratera, Mercè; Querol, Enrique; Piñol, Jaume; Fita, Ignacio; Calisto, Bárbara M.

    2015-01-01

    Several mycoplasmas, such as the emergent human pathogen Mycoplasma genitalium, developed a complex polar structure, known as the terminal organelle (TO), responsible for a new type of cellular motility, which is involved in a variety of cell functions: cell division, adherence to host cells, and virulence. The TO cytoskeleton is organized as a multisubunit dynamic motor, including three main ultrastructures: the terminal button, the electrodense core, and the wheel complex. Here, we describe the interaction between MG200 and MG491, two of the main components of the TO wheel complex that connects the TO with the cell body and the cell membrane. The interaction between MG200 and MG491 has a KD in the 80 nm range, as determined by surface plasmon resonance. The interface between the two partners was confined to the “enriched in aromatic and glycine residues” (EAGR) box of MG200, previously described as a protein-protein interaction domain, and to a 25-residue-long peptide from the C-terminal region of MG491 by surface plasmon resonance and NMR spectroscopy studies. An atomic description of the MG200 EAGR box binding surface was also provided by solution NMR. An M. genitalium mutant lacking the MG491 segment corresponding to the peptide reveals specific alterations in cell motility and cell morphology indicating that the MG200-MG491 interaction plays a key role in the stability and functioning of the TO. PMID:25471372

  9. Motility-Driven Glass and Jamming Transitions in Biological Tissues

    NASA Astrophysics Data System (ADS)

    Bi, Dapeng; Yang, Xingbo; Marchetti, M. Cristina; Manning, M. Lisa

    2016-04-01

    Cell motion inside dense tissues governs many biological processes, including embryonic development and cancer metastasis, and recent experiments suggest that these tissues exhibit collective glassy behavior. To make quantitative predictions about glass transitions in tissues, we study a self-propelled Voronoi model that simultaneously captures polarized cell motility and multibody cell-cell interactions in a confluent tissue, where there are no gaps between cells. We demonstrate that the model exhibits a jamming transition from a solidlike state to a fluidlike state that is controlled by three parameters: the single-cell motile speed, the persistence time of single-cell tracks, and a target shape index that characterizes the competition between cell-cell adhesion and cortical tension. In contrast to traditional particulate glasses, we are able to identify an experimentally accessible structural order parameter that specifies the entire jamming surface as a function of model parameters. We demonstrate that a continuum soft glassy rheology model precisely captures this transition in the limit of small persistence times and explain how it fails in the limit of large persistence times. These results provide a framework for understanding the collective solid-to-liquid transitions that have been observed in embryonic development and cancer progression, which may be associated with epithelial-to-mesenchymal transition in these tissues.

  10. Lattice-free models of directed cell motility

    NASA Astrophysics Data System (ADS)

    Irons, Carolyn; Plank, Michael J.; Simpson, Matthew J.

    2016-01-01

    Directed cell migration often occurs when individual cells move in response to an external chemical stimulus. Cells can respond by moving in either the direction of increasing (chemoattraction) or decreasing (chemorepulsion) concentration. Many previous models of directed cell migration use a lattice-based framework where agents undergo a lattice-based random walk and the direction of nearest-neighbour motility events is biased in a preferred direction. Such lattice-based models can lead to unrealistic configurations of agents, since the agents always move on an artificial lattice structure which is never observed experimentally. We present a lattice-free model of directed cell migration that incorporates two key features. First, agents move on a continuous domain, with the possibility that there is some preferred direction of motion. Second, to be consistent with experimental observations, we enforce a crowding mechanism so that motility events that would lead to agent overlap are not permitted. We compare simulation data from the new lattice-free model with a more traditional lattice-based model. To provide additional insight into the lattice-free model, we construct an approximate conservation statement which corresponds to a nonlinear advection-diffusion equation in the continuum limit. The solution of this mean-field model compares well with averaged data from the individual-based model.

  11. Automated real-time measurement of chemotactic cell motility.

    PubMed

    Hadjout, N; Laevsky, G; Knecht, D A; Lynes, M A

    2001-11-01

    We have developed a novel method, (ECIS/taxis), for monitoring cell movement in response to chemotactic and chemokinetic factors. In this system, cells migrate in an under-agarose environment, and their positions are monitored using the electric cell-substrate impedance sensor technology to measure the impedance change at a target electrode, that is lithographed onto the substrate, as the cells arrive at the target. In the studies reported here, Dictyostelium discoideum was used as a prototypical, motile eukaryotic cell. Using the ECIS/taxis system, the arrival of cells at the target electrode was proportional to the dose offolate used to stimulate the cells and could be assessed by changes in resistance at the electrode. ECIS/taxis was readily able to distinguish between wild-type cells and a mutant that is deficient in its chemotactic response. Finally, we have shown that an agent that interferes with chemotactic motility leads to the delayed arrival of cells at the target electrode. The multi-well assay configuration allows for simultaneous automated screening of many samples for chemotactic or anti-chemotactic activity. This assay system is compatible with measurements of mammalian cell movement and should be valuable in the assessment of both agonists and antagonists of cell movement.

  12. Regulation of gastrointestinal motility--insights from smooth muscle biology.

    PubMed

    Sanders, Kenton M; Koh, Sang Don; Ro, Seungil; Ward, Sean M

    2012-11-01

    Gastrointestinal motility results from coordinated contractions of the tunica muscularis, the muscular layers of the alimentary canal. Throughout most of the gastrointestinal tract, smooth muscles are organized into two layers of circularly or longitudinally oriented muscle bundles. Smooth muscle cells form electrical and mechanical junctions between cells that facilitate coordination of contractions. Excitation-contraction coupling occurs by Ca(2+) entry via ion channels in the plasma membrane, leading to a rise in intracellular Ca(2+). Ca(2+) binding to calmodulin activates myosin light chain kinase; subsequent phosphorylation of myosin initiates cross-bridge cycling. Myosin phosphatase dephosphorylates myosin to relax muscles, and a process known as Ca(2+) sensitization regulates the activity of the phosphatase. Gastrointestinal smooth muscles are 'autonomous' and generate spontaneous electrical activity (slow waves) that does not depend upon input from nerves. Intrinsic pacemaker activity comes from interstitial cells of Cajal, which are electrically coupled to smooth muscle cells. Patterns of contractile activity in gastrointestinal muscles are determined by inputs from enteric motor neurons that innervate smooth muscle cells and interstitial cells. Here we provide an overview of the cells and mechanisms that generate smooth muscle contractile behaviour and gastrointestinal motility.

  13. Trajectories of Listeria-type motility in two dimensions

    NASA Astrophysics Data System (ADS)

    Wen, Fu-Lai; Leung, Kwan-tai; Chen, Hsuan-Yi

    2012-12-01

    Force generated by actin polymerization is essential in cell motility and the locomotion of organelles or bacteria such as Listeria monocytogenes. Both in vivo and in vitro experiments on actin-based motility have observed geometrical trajectories including straight lines, circles, S-shaped curves, and translating figure eights. This paper reports a phenomenological model of an actin-propelled disk in two dimensions that generates geometrical trajectories. Our model shows that when the evolutions of actin density and force per filament on the disk are strongly coupled to the disk self-rotation, it is possible for a straight trajectory to lose its stability. When the instability is due to a pitchfork bifurcation, the resulting trajectory is a circle; a straight trajectory can also lose stability through a Hopf bifurcation, and the resulting trajectory is an S-shaped curve. We also show that a half-coated disk, which mimics the distribution of functionalized proteins in Listeria, also undergoes similar symmetry-breaking bifurcations when the straight trajectory loses stability. For both a fully coated disk and a half-coated disk, when the trajectory is an S-shaped curve, the angular frequency of the disk self-rotation is different from that of the disk trajectory. However, for circular trajectories, these angular frequencies are different for a fully coated disk but the same for a half-coated disk.

  14. Symmetry breaking in actin gels - Implications for cellular motility

    NASA Astrophysics Data System (ADS)

    John, Karin; Peyla, Philippe; Misbah, Chaouqi

    2007-03-01

    The physical origin of cell motility is not fully understood. Recently minimal model systems have shown, that polymerizing actin itself can produce a motile force, without the help of motor proteins. Pathogens like Shigella or Listeria use actin to propel themselves forward in their host cell. The same process can be mimicked with polystyrene beads covered with the activating protein ActA, which reside in a solution containing actin monomers. ActA induces the growth of an actin gel at the bead surface. Initially the gel grows symmetrically around the bead until a critical size is reached. Subsequently one observes a symmetry breaking and the gel starts to grow asymmetrically around the bead developing a tail of actin at one side. This symmetry breaking is accompanied by a directed movement of the bead, with the actin tail trailing behind the bead. Force generation relies on the combination of two properties: growth and elasticity of the actin gel. We study this phenomenon theoretically within the framework of a linear elasticity theory and linear flux-force relationships for the evolution of an elastic gel around a hard sphere. Conditions for a parity symmetry breaking are identified analytically and illustrated numerically with the help of a phasefield model.

  15. Modulation of Chlamydomonas reinhardtii flagellar motility by redox poise

    PubMed Central

    Wakabayashi, Ken-ichi; King, Stephen M.

    2006-01-01

    Redox-based regulatory systems are essential for many cellular activities. Chlamydomonas reinhardtii exhibits alterations in motile behavior in response to different light conditions (photokinesis). We hypothesized that photokinesis is signaled by variations in cytoplasmic redox poise resulting from changes in chloroplast activity. We found that this effect requires photosystem I, which generates reduced NADPH. We also observed that photokinetic changes in beat frequency and duration of the photophobic response could be obtained by altering oxidative/reductive stress. Analysis of reactivated cell models revealed that this redox poise effect is mediated through the outer dynein arms (ODAs). Although the global redox state of the thioredoxin-related ODA light chains LC3 and LC5 and the redox-sensitive Ca2+-binding subunit of the docking complex DC3 did not change upon light/dark transitions, we did observe significant alterations in their interactions with other flagellar components via mixed disulfides. These data indicate that redox poise directly affects ODAs and suggest that it may act in the control of flagellar motility. PMID:16754958

  16. Realizing the Physics of Motile Cilia Synchronization with Driven Colloids

    NASA Astrophysics Data System (ADS)

    Bruot, Nicolas; Cicuta, Pietro

    2016-03-01

    Cilia and flagella in biological systems often show large scale cooperative behaviors such as the synchronization of their beats in "metachronal waves." These are beautiful examples of emergent dynamics in biology, and are essential for life, allowing diverse processes from the motility of eukaryotic microorganisms, to nutrient transport and clearance of pathogens from mammalian airways. How these collective states arise is not fully understood, but it is clear that individual cilia interact mechanically, and that a strong and long-ranged component of the coupling is mediated by the viscous fluid. We review here the work by ourselves and others aimed at understanding the behavior of hydrodynamically coupled systems, and particularly a set of results that have been obtained both experimentally and theoretically by studying actively driven colloidal systems. In these controlled scenarios, it is possible to selectively test aspects of living motile cilia, such as the geometrical arrangement, the effects of the driving profile and the distance to no-slip boundaries. We outline and give examples of how it is possible to link model systems to observations on living systems, which can be made on microorganisms, on cell cultures or on tissue sections. This area of research has clear clinical application in the long term, as severe pathologies are associated with compromised cilia function in humans.

  17. Learning and memory: an emergent property of cell motility.

    PubMed

    Baudry, Michel; Bi, Xiaoning

    2013-09-01

    In this review, we develop the argument that the molecular/cellular mechanisms underlying learning and memory are an adaptation of the mechanisms used by all cells to regulate cell motility. Neuronal plasticity and more specifically synaptic plasticity are widely recognized as the processes by which information is stored in neuronal networks engaged during the acquisition of information. Evidence accumulated over the last 25 years regarding the molecular events underlying synaptic plasticity at excitatory synapses has shown the remarkable convergence between those events and those taking place in cells undergoing migration in response to extracellular signals. We further develop the thesis that the calcium-dependent protease, calpain, which we postulated over 25 years ago to play a critical role in learning and memory, plays a central role in the regulation of both cell motility and synaptic plasticity. The findings discussed in this review illustrate the general principle that fundamental cell biological processes are used for a wide range of functions at the level of organisms.

  18. Orbital implants insertion to improve ocular prostheses motility.

    PubMed

    Goiato, Marcelo Coelho; Haddad, Marcela Filié; dos Santos, Daniela Micheline; Pesqueira, Aldiéris Alves; Ribeiro, Paula do Prado; Moreno, Amália

    2010-05-01

    The objectives of this study were, through a literature review, to point the differences between orbital implants and their advantages and disadvantages, to evaluate prosthesis motility after orbital implants are inserted, and to point the implant wrapping current risks. Sixty-seven articles were reviewed. Enucleation implants can be autoplastics or alloplastics and porous (including natural and synthetic hydroxyapatite [HA]) or nonporous (silicone). Hydroxyapatite is the most related in the literature, but it has disadvantages, too, that is, all orbital implants must be wrapped. Exposure of the porous orbital implant can be repaired using different materials, which include homologous tissue, as well as autogenous graft, xenograft, and synthetic material mesh. The most used materials are HA and porous polyethylene orbital implant. The HA implant is expensive and possibly subject corals to damage, different from porous polyethylene orbital implants. Porous implants show the best prosthesis motility and a minimum rate of implants extrusion. Implant wraps can facilitate smoother entry of the implant into the orbit and allow reattachment of extraocular muscles. They also serve as a barrier between the overlying soft tissue and the rough surface of the implant, protecting implants from exposure or erosion.

  19. [Primary esophageal motility disorders; especially about esophageal achalasia].

    PubMed

    Miyazaki, Tatsuya; Sohda, Makoto; Sakai, Makoto; Tanaka, Naritaka; Suzuki, Shigemasa; Yokobori, Takehiko; Inose, Takanori; Nakajima, Masanobu; Fukuchi, Minoru; Kato, Hiroyuki; Kusano, Motoyasu; Kuwano, Hiroyuki

    2011-07-01

    Esophageal motility disorders are classified primary and secondary, and primary esophageal motility disorders are classified esophageal achalasia and other diseases by manometry. An esophageal emptying disorder associated with insufficient relaxation of the lower esophageal sphincter (LES) and elimination of peristaltic waves on the esophageal body is the major abnormality of achalasia. Esophagogram, endoscopy, and manometry are used for diagnosis. As pharmacological therapy, administration of a calcium channel blocker or nitrate is useful. The pharmacological therapy is not recommended as long-term basic therapy but as a temporary treatment. At 1st, the balloon dilation method is chosen in treatment of achalasia Surgical treatment is indicated in the following cases: (1) Patients uneffected by balloon dilation, (2) Flask type with grade II to III dilation, and sigmoid type, (3) the gradual progression to the pathophysiological stage, (4) young patients, (5) complicated with esophageal cancer. Laparoscopic Heller-Dor procedure is the most popular surgical procedure, recently. It is somewhat difficult to perform surgical treatment for this functional disease. We should select the most suitable individualized treatment with efficient comprehension of the pathophysiological situation.

  20. In vitro motility from recombinant dynein heavy chain.

    PubMed Central

    Mazumdar, M; Mikami, A; Gee, M A; Vallee, R B

    1996-01-01

    The dyneins are a class of motor protein involved in ciliary and flagellar motility, organelle transport, and chromosome segregation. Because of their large size and subunit complexity, relatively little is known about their mechanisms of force production and regulation. We report here on the expression and analysis of the entire rat cytoplasmic dynein heavy chain (Mr 532,000). Full-length cDNAs were constructed from a series of partial clones and tagged at the C terminus with either a FLAG-epitope tag or a His6-tag. The recombinant polypeptides were expressed either in insect cells by baculovirus infection or in COS-7 cells by transient transfection. The recombinant protein was mostly soluble and showed good microtubule binding. It exhibited a broad sedimentation profile, indicative of the formation of dimers as well as higher order multimers. Good microtubule gliding motility activity was observed in assays of heavy chain expressed in either insect or COS-7 cells. Average microtubule gliding velocities of 1.2-1.8 microm/sec were observed, comparable with the rates determined for calf brain cytoplasmic dynein. These results represent the first indication that recombinant heavy chain alone is capable of force production, and should lead to rapid progress in defining the dynein motor domain. Images Fig. 1 Fig. 2 Fig. 3 PMID:8692854

  1. Thermodynamics of the motility-induced phase separation

    NASA Astrophysics Data System (ADS)

    Solon, Alexandre; Stenhammar, Joachim; Cates, Michael; Tailleur, Julien

    Self-propelled particles are known to accumulate in regions of space where their velocity is lowered. In addition, if their velocity diminishes when the local density increases (for example due to crowding effects), a positive feedback loop leads to the now well-established motility-induced phase separation (MIPS) between a dense immotile phase and a dilute motile phase. Understanding the phase equilibrium of MIPS is still a matter of debate. Although, depending on the models used to study the transition, a chemical potential or a pressure can be defined, these quantities do not play their usual thermodynamic role. In particular, the usual common tangent or equal-area constructions fail in these systems. Indeed, we will show that describing the phase equilibrium of MIPS necessitates generalized thermodynamics that include non-equilibrium contributions. This approach allows us to predict correctly the phase diagram of MIPS and to gain insight into the thermodynamics of active systems. It also sheds light on the (in)equivalence of statistical ensembles for these systems, paving the way for more efficient computational studies.

  2. Bacterial Adaptation during Chronic Respiratory Infections

    PubMed Central

    Cullen, Louise; McClean, Siobhán

    2015-01-01

    Chronic lung infections are associated with increased morbidity and mortality for individuals with underlying respiratory conditions such as cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). The process of chronic colonisation allows pathogens to adapt over time to cope with changing selection pressures, co-infecting species and antimicrobial therapies. These adaptations can occur due to environmental pressures in the lung such as inflammatory responses, hypoxia, nutrient deficiency, osmolarity, low pH and antibiotic therapies. Phenotypic adaptations in bacterial pathogens from acute to chronic infection include, but are not limited to, antibiotic resistance, exopolysaccharide production (mucoidy), loss in motility, formation of small colony variants, increased mutation rate, quorum sensing and altered production of virulence factors associated with chronic infection. The evolution of Pseudomonas aeruginosa during chronic lung infection has been widely studied. More recently, the adaptations that other chronically colonising respiratory pathogens, including Staphylococcus aureus, Burkholderia cepacia complex and Haemophilus influenzae undergo during chronic infection have also been investigated. This review aims to examine the adaptations utilised by different bacterial pathogens to aid in their evolution from acute to chronic pathogens of the immunocompromised lung including CF and COPD. PMID:25738646

  3. Bacterial Trapping in Porous Media Flows

    NASA Astrophysics Data System (ADS)

    Dehkharghani, Amin; Waisbord, Nicolas; Dunkel, Jörn; Guasto, Jeffrey

    2016-11-01

    Swimming bacteria inhabit heterogeneous, microstructured environments that are often characterized by complex, ambient flows. Understanding the physical mechanisms underlying cell transport in these systems is key to controlling important processes such as bioremediation in porous soils and infections in human tissues. We study the transport of swimming bacteria (Bacillus subtilis) in quasi-two-dimensional porous microfluidic channels with a range of periodic microstructures and flow strengths. Measured cell trajectories and the local cell number density reveal the formation of filamentous cell concentration patterns within the porous structures. The local cell densification is maximized at shear rates in the range 1-10 s-1, but widely varies with pore geometry and flow topology. Experimental observations are complemented by Langevin simulations to demonstrate that the filamentous patterns result from a coupling of bacterial motility to the complex flow fields via Jeffery orbits, which effectively 'trap' the bacteria on streamlines. The resulting microscopic heterogeneity observed here suppresses bacterial transport and likely has implications for both mixing and cell nutrient uptake in porous media flows. NSF CBET-1511340.

  4. The Selective Value of Bacterial Shape

    PubMed Central

    Young, Kevin D.

    2006-01-01

    Why do bacteria have shape? Is morphology valuable or just a trivial secondary characteristic? Why should bacteria have one shape instead of another? Three broad considerations suggest that bacterial shapes are not accidental but are biologically important: cells adopt uniform morphologies from among a wide variety of possibilities, some cells modify their shape as conditions demand, and morphology can be tracked through evolutionary lineages. All of these imply that shape is a selectable feature that aids survival. The aim of this review is to spell out the physical, environmental, and biological forces that favor different bacterial morphologies and which, therefore, contribute to natural selection. Specifically, cell shape is driven by eight general considerations: nutrient access, cell division and segregation, attachment to surfaces, passive dispersal, active motility, polar differentiation, the need to escape predators, and the advantages of cellular differentiation. Bacteria respond to these forces by performing a type of calculus, integrating over a number of environmental and behavioral factors to produce a size and shape that are optimal for the circumstances in which they live. Just as we are beginning to answer how bacteria create their shapes, it seems reasonable and essential that we expand our efforts to understand why they do so. PMID:16959965

  5. Osmotic Pressure in a Bacterial Swarm

    PubMed Central

    Ping, Liyan; Wu, Yilin; Hosu, Basarab G.; Tang, Jay X.; Berg, Howard C.

    2014-01-01

    Using Escherichia coli as a model organism, we studied how water is recruited by a bacterial swarm. A previous analysis of trajectories of small air bubbles revealed a stream of fluid flowing in a clockwise direction ahead of the swarm. A companion study suggested that water moves out of the agar into the swarm in a narrow region centered ∼30 μm from the leading edge of the swarm and then back into the agar (at a smaller rate) in a region centered ∼120 μm back from the leading edge. Presumably, these flows are driven by changes in osmolarity. Here, we utilized green/red fluorescent liposomes as reporters of osmolarity to verify this hypothesis. The stream of fluid that flows in front of the swarm contains osmolytes. Two distinct regions are observed inside the swarm near its leading edge: an outer high-osmolarity band (∼30 mOsm higher than the agar baseline) and an inner low-osmolarity band (isotonic or slightly hypotonic to the agar baseline). This profile supports the fluid-flow model derived from the drift of air bubbles and provides new (to our knowledge) insights into water maintenance in bacterial swarms. High osmotic pressure at the leading edge of the swarm extracts water from the underlying agar and promotes motility. The osmolyte is of high molecular weight and probably is lipopolysaccharide. PMID:25140422

  6. Demonstrating Bacterial Flagella.

    ERIC Educational Resources Information Center

    Porter, John R.; And Others

    1992-01-01

    Describes an effective laboratory method for demonstrating bacterial flagella that utilizes the Proteus mirabilis organism and a special harvesting technique. Includes safety considerations for the laboratory exercise. (MDH)

  7. Novel single-tube agar-based test system for motility enhancement and immunocapture of Escherichia coli O157:H7 by H7 flagellar antigen-specific antibodies.

    PubMed

    Murinda, Shelton E; Nguyen, Lien T; Ivey, Susan J; Almeida, Raul A; Oliver, Stephen P

    2002-12-01

    This paper describes a novel single-tube agar-based technique for motility enhancement and immunoimmobilization of Escherichia coli O157:H7. Motility indole ornithine medium and agar (0.4%, wt/vol) media containing either nutrient broth, tryptone broth, or tryptic soy broth (TSBA) were evaluated for their abilities to enhance bacterial motility. Twenty-six E. coli strains, including 19 O157:H7 strains, 1 O157:H(-) strain, and 6 generic E. coli strains, were evaluated. Test bacteria were stab inoculated in the center of the agar column, and tubes were incubated at 37 degrees C for 18 to 96 h. Nineteen to 24 of the 26 test strains (73.1 to 92.3%) were motile in the different media. TSBA medium performed best and was employed in subsequent studies of motility enhancement and H7 flagellar immunocapture. H7 flagellar antiserum (30 and 60 micro l) mixed with TSBA was placed as a band (1 ml) in the middle of an agar column separating the top (3-ml) and bottom (3-ml) agar layers. The top agar layer was inoculated with the test bacterial strains. The tubes were incubated at 37 degrees C for 12 to 18 h and for 18 to 96 h. The specificity and sensitivity of the H7 flagellar immunocapture tests were 75 and 100%, respectively. The procedure described is simple and sensitive and could be adapted easily for routine use in laboratories that do not have sophisticated equipment and resources for confirming the presence of H7 flagellar antigens. Accurate and rapid identification of H7 flagellar antigen is critical for the complete characterization of E. coli O157:H7, owing to the immense clinical, public health, and economic significance of this food-borne pathogen.

  8. Multiscale modeling of bacterial colonies: how pili mediate the dynamics of single cells and cellular aggregates

    NASA Astrophysics Data System (ADS)

    Pönisch, Wolfram; Weber, Christoph A.; Juckeland, Guido; Biais, Nicolas; Zaburdaev, Vasily

    2017-01-01

    Neisseria gonorrhoeae is the causative agent of one of the most common sexually transmitted diseases, gonorrhea. Over the past two decades there has been an alarming increase of reported gonorrhea cases where the bacteria were resistant to the most commonly used antibiotics thus prompting for alternative antimicrobial treatment strategies. The crucial step in this and many other bacterial infections is the formation of microcolonies, agglomerates consisting of up to several thousands of cells. The attachment and motility of cells on solid substrates as well as the cell-cell interactions are primarily mediated by type IV pili, long polymeric filaments protruding from the surface of cells. While the crucial role of pili in the assembly of microcolonies has been well recognized, the exact mechanisms of how they govern the formation and dynamics of microcolonies are still poorly understood. Here, we present a computational model of individual cells with explicit pili dynamics, force generation and pili-pili interactions. We employ the model to study a wide range of biological processes, such as the motility of individual cells on a surface, the heterogeneous cell motility within the large cell aggregates, and the merging dynamics and the self-assembly of microcolonies. The results of numerical simulations highlight the central role of pili generated forces in the formation of bacterial colonies and are in agreement with the available experimental observations. The model can quantify the behavior of multicellular bacterial colonies on biologically relevant temporal and spatial scales and can be easily adjusted to include the geometry and pili characteristics of various bacterial species. Ultimately, the combination of the microbiological experimental approach with the in silico model of bacterial colonies might provide new qualitative and quantitative insights on the development of bacterial infections and thus pave the way to new antimicrobial treatments.

  9. Effects of seasons on some semen parameters and bacterial contamination of Awassi ram semen.

    PubMed

    Azawi, O I; Ismaeel, M A

    2012-06-01

    The objectives of the present study were to determine the effects of season on some semen parameters and bacterial contamination of Awassi ram semen. Semen samples from six mature Awassi rams were used in this study. Semen collection was performed with artificial vagina every week, from September 2009 to October 2010. Volume, sperm concentration, mass motility, individual motility, percentage live sperm and sperm abnormalities were evaluated. Moreover, determination of viable bacterial count of the rams was also recorded weekly. Higher (p < 0.05) semen volume in the hot summer and spring months was observed of August (1.55 ± 0.08 ml) and March (1.27 ± 0.15 ml). Sperm concentration was highest (p < 0.05) in the breeding season (late summer to early autumn) of September (4.21 ± 0.86 × 10(9) sperm/ml). Sperm individual motility and percent of live sperm observed in August (summer) and May (end of spring) when the environmental temperature started to increase were recorded highest values and differed significantly (p < 0.05) from December and January (winter). The highest value of the mean sperm acrosomal defects (13.33 ± 0.63%) was recorded in December. The highest value of the mean viable bacterial count (138.3 ± 21.6) was recorded in July (summer). A significant decrease (p < 0.01) in the mean viable bacterial count was observed from the middle of winter towards the end of spring. The lowest bacterial count was noted in January (60.5 ± 2.98). It could be concluded from the results of the present study that there is an effect of season on ram semen quality, and summer high temperature in northern Iraq has no effect on Awassi ram semen. There is a significant effect of season on bacterial count on Awassi ram semen.

  10. Mutation of a Salmonella serogroup-C1-specific gene abrogates O7-antigen biosynthesis and triggers NaCl-dependent motility deficiency.

    PubMed

    Zhou, Xiujuan; Liu, Bin; Shi, Chunlei; Shi, Xianming

    2014-01-01

    Several molecular detection marker genes specific for a number of individual Salmonella serogroups have been recently identified in our lab by comparative genomics for the genotyping of diverse serogroups. To further understand the correlation between serotype and genotype, the function of a Salmonella serogroup-C1-specific gene (SC_2092) was analyzed in this study. It was indicated from the topological prediction using the deduced amino acid sequence of SC_2092 that this putative protein was highly similar to the confirmed Wzx flippases. Furthermore, SDS-PAGE revealed that lipopolysaccharide (LPS) biosynthesis, specifically O-antigen synthesis, was incomplete in an SC_2092 in-frame deletion mutant, and no agglutination reaction with the O7 antibody was exhibited in this mutant. Therefore, it was revealed that this Salmonella serogroup-C1-specific gene SC_2092 encoded a putative flippase, which was required for O7-polysaccharide biosynthesis, and was designated here as wzxC1. Subsequently, the effects of the deletion of wzxC1 on bacterial motility and sodium chloride (NaCl) tolerance were evaluated. The wzxC1 mutant lacked swarming motility on solid surfaces and was impaired in swimming motility in soft agar. Moreover, microscopic examination and RT-qPCR exhibited that an increased auto-aggregation and a strong defect in flagella expression, respectively, were responsible for the reduced motility in this mutant. In addition, the wzxC1 mutant was more sensitive than the wild-type strain to NaCl, and auto-aggregation of mutant cells was observed immediately up on the addition of 1% NaCl to the medium. Interestingly, the motility deficiency of the mutant strain, as well as the cell agglomeration and the decrease in flagellar expression, were relieved in a NaCl-free medium. This is the first study to experimentally demonstrate a connection between a Salmonella serogroup specific gene identified by comparative genomics with the synthesis of a specific O

  11. The measurement of bacterial translation by photon correlation spectroscopy.

    PubMed Central

    Stock, G B; Jenkins, T C

    1978-01-01

    Photon correlation spectroscopy is shown to be a practical technique for the accurate determination of translational speeds of bacteria. Though other attempts have been made to use light scattering as a probe of various aspects of bacterial motility, no other comprehensive studies to establish firmly the basic capabilities and limitations of the technique have been published. The intrinsic accuracy of the assay of translational speeds by photon correlation spectroscopy is investigated by analysis of synthetic autocorrelation data; consistently accurate estimates of the mean and second moment of the speed distribution can be calculated. Extensive analyses of experimental preparations of Salmonella typhimurium examine the possible sources of experimental difficulty with the assay. Cinematography confirms the bacterial speed estimates obtained by photon correlation techniques. PMID:346073

  12. Recent progresses on AI-2 bacterial quorum sensing inhibitors.

    PubMed

    Zhu, Peng; Li, Minyong

    2012-01-01

    Quorum sensing (QS) is a communication procedure that predominates gene expression in response to cell density and fluctuations in the neighboring environment as a result of discerning molecules termed autoinducers (AIs). It has been embroiled that QS can govern bacterial behaviors such as the secretion of virulence factors, biofilm formation, bioluminescence production, conjugation, sporulation and swarming motility. Autoinducer 2 (AI-2), a QS signaling molecule brought up to be involved in interspecies communication, exists in both gram-negative and -positive bacteria. Therefore, novel approaches to interrupt AI-2 quorum sensing are being recognized as next generation antimicrobials. In the present review article, we summarized recent progresses on AI-2 bacterial quorum sensing inhibitors and discussed their potential as the antibacterial agents.

  13. Genome sequence of Xanthomonas fuscans subsp. fuscans strain 4834-R reveals that flagellar motility is not a general feature of xanthomonads

    PubMed Central

    2013-01-01

    Background Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences. Results Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations. Conclusions This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness. PMID:24195767

  14. FlhF, a signal recognition particle-like GTPase, is involved in the regulation of flagellar arrangement, motility behaviour and protein secretion in Bacillus cereus.

    PubMed

    Salvetti, Sara; Ghelardi, Emilia; Celandroni, Francesco; Ceragioli, Mara; Giannessi, Francesco; Senesi, Sonia

    2007-08-01

    Flagellar arrangement is a highly conserved feature within bacterial species. However, only a few genes regulating cell flagellation have been described in polar flagellate bacteria. This report demonstrates that the arrangement of flagella in the peritrichous flagellate Bacillus cereus is controlled by flhF. Disruption of flhF in B. cereus led to a reduction in the number of flagella from 10-12 to 1-3 filaments per cell in the insertion mutant MP06. Moreover, compared to the parental strain, MP06 exhibited: (i) shorter smooth swimming phases, causing reduced swimming motility but not affecting chemotaxis; (ii) complete inhibition of swarming motility, as differentiated swarm cells were never detected; (iii) an increased amount of extracellular proteins; and (iv) differential export of virulence determinants, such as haemolysin BL (HBL), phosphatidylcholine-preferring phospholipase C (PC-PLC) and non-haemolytic enterotoxin (NHE). Introduction of a plasmid harbouring flhF (pDGflhF) into MP06 completely restored the wild-type phenotype in the trans-complemented strain MP07. B. cereus flhF was found to constitute a monocistronic transcriptional unit and its overexpression did not produce abnormal features in the wild-type background. Characterization of a B. cereus mutant (MP05) carrying a partial flhF deletion indicated that the last C-terminal domain of FlhF is involved in protein export while not required for flagellar arrangement and motility behaviour. Taken together, these data suggest that B. cereus FlhF is a promising candidate for connecting diverse cellular functions, such as flagellar arrangement, motility behaviour, pattern of protein secretion and virulence phenotype.

  15. Analysis of the Borrelia burgdorferi Cyclic-di-GMP-Binding Protein PlzA Reveals a Role in Motility and Virulence ▿

    PubMed Central

    Pitzer, Joshua E.; Sultan, Syed Z.; Hayakawa, Yoshihiro; Hobbs, Gerry; Miller, Michael R.; Motaleb, Md A.

    2011-01-01

    The cyclic-dimeric-GMP (c-di-GMP)-binding protein PilZ has been implicated in bacterial motility and pathogenesis. Although BB0733 (PlzA), the only PilZ domain-containing protein in Borrelia burgdorferi, was reported to bind c-di-GMP, neither its role in motility or virulence nor it's affinity for c-di-GMP has been reported. We determined that PlzA specifically binds c-di-GMP with high affinity (dissociation constant [Kd], 1.25 μM), consistent with Kd values reported for c-di-GMP-binding proteins from other bacteria. Inactivation of the monocistronically transcribed plzA resulted in an opaque/solid colony morphology, whereas the wild-type colonies were translucent. While the swimming pattern of mutant cells appeared normal, on swarm plates, mutant cells exhibited a significantly reduced swarm diameter, demonstrating a role of plzA in motility. Furthermore, the plzA mutant cells were significantly less infectious in experimental mice (as determined by 50% infectious dose [ID50]) relative to wild-type spirochetes. The mutant also had survival rates in fed ticks lower than those of the wild type. Consequently, plzA mutant cells failed to complete the mouse-tick-mouse infection cycle, indicating plzA is essential for the enzootic life cycle of B. burgdorferi. All of these defects were corrected when the mutant was complemented in cis. We propose that failure of plzA mutant cells to infect mice was due to altered motility; however, the possibility that an unidentified factor(s) contributed to interruption of the B. burgdorferi enzootic life cycle cannot yet be excluded. PMID:21357718

  16. Regulation of bacterial cell polarity by small GTPases.

    PubMed

    Keilberg, Daniela; Søgaard-Andersen, Lotte

    2014-04-01

    Bacteria are polarized with many proteins localizing dynamically to specific subcellular sites. Two GTPase families have important functions in the regulation of bacterial cell polarity, FlhF homologues and small GTPases of the Ras superfamily. The latter consist of only a G domain and are widespread in bacteria. The rod-shaped Myxococcus xanthus cells have two motility systems, one for gliding and one that depends on type IV pili. The function of both systems hinges on proteins that localize asymmetrically to the cell poles. During cellular reversals, these asymmetrically localized proteins are released from their respective poles and then bind to the opposite pole, resulting in an inversion of cell polarity. Here, we review genetic, cell biological, and biochemical analyses that identified two modules containing small Ras-like GTPases that regulate the dynamic polarity of motility proteins. The GTPase SofG interacts directly with the bactofilin cytoskeletal protein BacP to ensure polar localization of type IV pili proteins. In the second module, the small GTPase MglA, its cognate GTPase activating protein (GAP) MglB, and the response regulator RomR localize asymmetrically to the poles and sort dynamically localized motility proteins to the poles. During reversals, MglA, MglB, and RomR switch poles, in that way inducing the relocation of dynamically localized motility proteins. Structural analyses have demonstrated that MglB has a Roadblock/LC7 fold, the central β2 strand in MglA undergoes an unusual screw-type movement upon GTP binding, MglA contains an intrinsic Arg finger required for GTP hydrolysis, and MglA and MglB form an unusual G protein/GAP complex with a 1:2 stoichiometry.

  17. In Silico Reconstitution of Actin-Based Symmetry Breaking and Motility

    PubMed Central

    Dayel, Mark J.; Akin, Orkun; Landeryou, Mark; Risca, Viviana; Mogilner, Alex; Mullins, R. Dyche

    2009-01-01

    Eukaryotic cells assemble viscoelastic networks of crosslinked actin filaments to control their shape, mechanical properties, and motility. One important class of actin network is nucleated by the Arp2/3 complex and drives both membrane protrusion at the leading edge of motile cells and intracellular motility of pathogens such as Listeria monocytogenes. These networks can be reconstituted in vitro from purified components to drive the motility of spherical micron-sized beads. An Elastic Gel model has been successful in explaining how these networks break symmetry, but how they produce directed motile force has been less clear. We have combined numerical simulations with in vitro experiments to reconstitute the behavior of these motile actin networks in silico using an Accumulative Particle-Spring (APS) model that builds on the Elastic Gel model, and demonstrates simple intuitive mechanisms for both symmetry breaking and sustained motility. The APS model explains observed transitions between smooth and pulsatile motion as well as subtle variations in network architecture caused by differences in geometry and conditions. Our findings also explain sideways symmetry breaking and motility of elongated beads, and show that elastic recoil, though important for symmetry breaking and pulsatile motion, is not necessary for smooth directional motility. The APS model demonstrates how a small number of viscoelastic network parameters and construction rules suffice to recapture the complex behavior of motile actin networks. The fact that the model not only mirrors our in vitro observations, but also makes novel predictions that we confirm by experiment, suggests that the model captures much of the essence of actin-based motility in this system. PMID:19771152

  18. A systematic analysis of the role of GGDEF-EAL domain proteins in virulence and motility in Xanthomonas oryzae pv. oryzicola

    PubMed Central

    Wei, Chao; Jiang, Wendi; Zhao, Mengran; Ling, Junjie; Zeng, Xin; Deng, Jun; Jin, Dongli; Dow, John Maxwell; Sun, Wenxian

    2016-01-01

    The second messenger c-di-GMP is implicated in regulation of various aspects of the lifestyles and virulence of Gram-negative bacteria. Cyclic di-GMP is formed by diguanylate cyclases with a GGDEF domain and degraded by phosphodiesterases with either an EAL or HD-GYP domain. Proteins with tandem GGDEF-EAL domains occur in many bacteria, where they may be involved in c-di-GMP turnover or act as enzymatically-inactive c-di-GMP effectors. Here, we report a systematic study of the regulatory action of the eleven GGDEF-EAL proteins in Xanthomonas oryzae pv. oryzicola, an important rice pathogen causing bacterial leaf streak. Mutational analysis revealed that XOC_2335 and XOC_2393 positively regulate bacterial swimming motility, while XOC_2102, XOC_2393 and XOC_4190 negatively control sliding motility. The ΔXOC_2335/XOC_2393 mutant that had a higher intracellular c-di-GMP level than the wild type and the ΔXOC_4190 mutant exhibited reduced virulence to rice after pressure inoculation. In vitro purified XOC_4190 and XOC_2102 have little or no diguanylate cyclase or phosphodiesterase activity, which is consistent with unaltered c-di-GMP concentration in ΔXOC_4190. Nevertheless, both proteins can bind to c-di-GMP with high affinity, indicating a potential role as c-di-GMP effectors. Overall our findings advance understanding of c-di-GMP signaling and its links to virulence in an important rice pathogen. PMID:27053282

  19. Functional and proteomic analyses reveal that wxcB is involved in virulence, motility, detergent tolerance, and biofilm formation in Xanthomonas campestris pv. vesicatoria.

    PubMed

    Park, Hye-Jee; Jung, Ho Won; Han, Sang-Wook

    2014-09-26

    The bacterial envelope possesses diverse functions, including protection against environmental stress and virulence factors for host infection. Here, we report the function of wxcB in Xanthomonas campestris pv. vesicatoria (Xcv), a causal agent of bacterial leaf spot disease in tomato and pepper. To characterize roles of wxcB, we generated a knockout mutant (XcvΔwxcB) and found that the virulence of the mutant was weaker than that of the wild type in tomato plants. To predict the mechanism affected by wxcB, we compared protein expressions between the wild type and the mutant. Expression of 152 proteins showed a greater than 2-fold difference. Proteins involved in motility and cell wall/membrane were the most abundant. Through phenotypic assays, we further demonstrated that the mutant displayed reduced motility and tolerance to treatment, but it showed increased biofilm formation. Interestingly, the LPS profile was unchanged. These results lead to new insights into the functions of wxcB that is associated with cell wall/membrane functions, which contributes to pathogen virulence.

  20. Rac regulates vascular endothelial growth factor stimulated motility.

    PubMed

    Soga, N; Connolly, J O; Chellaiah, M; Kawamura, J; Hruska, K A

    2001-01-01

    During angiogenesis endothelial cells migrate towards a chemotactic stimulus. Understanding the mechanism of endothelial cell migration is critical to the therapeutic manipulation of angiogenesis and ultimately cancer prevention. Vascular endothelial growth factor (VEGF) is a potent chemotactic stimulus of endothelial cells during angiogenesis. The endothelial cell signal transduction pathway of VEGF represents a potential target for cancer therapy, but the mechanisms of post-receptor signal transduction including the roles of rho family GTPases in regulating the cytoskeletal effects of VEGF in endothelial cells are not understood. Here we analyze the mechanisms of cell migration in the mouse brain endothelial cell line (bEND3). Stable transfectants containing a tetracycline repressible expression vector were used to induce expression of Rac mutants. Endothelial cell haptotaxis was stimulated by constitutively active V12Rac on collagen and vitronectin coated supports, and chemotaxis was further stimulated by VEGF. Osteopontin coated supports were the most stimulatory to bEND3 haptotaxis, but VEGF was not effective in further increasing migration on osteopontin coated supports. Haptotaxis on support coated with collagen, vitronectin, and to a lesser degree osteopontin was inhibited by N17 Rac. N17 Rac expression blocked stimulation of endothelial cell chemotaxis by VEGF. As part of the chemotactic stimulation, VEGF caused a loss of actin organization at areas of cell-cell contact and increased stress fiber expression in endothelial cells which were directed towards pores in the transwell membrane. N17 Rac prevented the stimulation of cell-cell contact disruption and the stress fiber stimulation by VEGF. These data demonstrate two pathways of regulating endothelial cell motility, one in which Rac is activated by matrix/integrin stimulation and is a crucial modulator of endothelial cell haptotaxis. The other pathway, in the presence of osteopontin, is Rac independent

  1. Vimentin in Bacterial Infections

    PubMed Central

    Mak, Tim N.; Brüggemann, Holger

    2016-01-01

    Despite well-studied bacterial strategies to target actin to subvert the host cell cytoskeleton, thus promoting bacterial survival, replication, and dissemination, relatively little is known about the bacterial interaction with other components of the host cell cytoskeleton, including intermediate filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge about the role of IFs in bacterial infections, focusing on the type III IF protein vimentin. Recent studies have revealed the involvement of vimentin in host cell defenses, acting as ligand for several pattern recognition receptors of the innate immune system. Two main aspects of bacteria-vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial virulence factors that target vimentin to subvert its function in order to change the host cell fate in the course of a bacterial infection. PMID:27096872

  2. Investigation of bacterial chemotaxis in flow-based microfluidic devices.

    PubMed

    Englert, Derek L; Manson, Michael D; Jayaraman, Arul

    2010-05-01

    The plug-in-pond and capillary assays are convenient methods for measuring attractant and repellent bacterial chemotaxis. However, these assays do not provide quantitative information on the extent of migration and are not well-suited for investigating repellent taxis. Here, we describe a protocol for a flow-based microfluidic system (microFlow) to quantitatively investigate chemotaxis in response to concentration gradients of attractants and repellents. The microFlow device uses diffusive mixing to generate concentration gradients that are stable throughout the chemotaxis chamber and for the duration of the experiment. The gradients may be of any desired absolute concentration and gradient strength. GFP-expressing bacteria immediately encounter a stable concentration gradient when they enter the chemotaxis chamber, and the migration in response to the gradient is monitored by microscopy. The effects of different parameters that influence the extent of migration in the microFlow device-preparation of the motile bacterial population preparation, strength of the concentration gradient and duration of exposure to the gradient-are discussed in the context of repellent taxis of chemotactically wild-type Escherichia coli cells in a gradient of NiSO(4). Fabrication of the microfluidic device takes 1 d while preparing motile cells and carrying out the chemotaxis experiment takes 4-6 h to complete.

  3. Analysis of bacterial migration. 2: Studies with multiple attractant gradients

    SciTech Connect

    Strauss, I.; Frymier, P.D.; Hahn, C.M.; Ford, R.M. . Dept. of Chemical Engineering)

    1995-02-01

    Many motile bacteria exhibit chemotaxis, the ability to bias their random motion toward or away from increasing concentrations of chemical substances which benefit or inhibit their survival, respectively. Since bacteria encounter numerous chemical concentration gradients simultaneously in natural surroundings, it is necessary to know quantitatively how a bacterial population responds in the presence of more than one chemical stimulus to develop predictive mathematical models describing bacterial migration in natural systems. This work evaluates three hypothetical models describing the integration of chemical signals from multiple stimuli: high sensitivity, maximum signal, and simple additivity. An expression for the tumbling probability for individual stimuli is modified according to the proposed models and incorporated into the cell balance equation for a 1-D attractant gradient. Random motility and chemotactic sensitivity coefficients, required input parameters for the model, are measured for single stimulus responses. Theoretical predictions with the three signal integration models are compared to the net chemotactic response of Escherichia coli to co- and antidirectional gradients of D-fucose and [alpha]-methylaspartate in the stopped-flow diffusion chamber assay. Results eliminate the high-sensitivity model and favor the simple additivity over the maximum signal. None of the simple models, however, accurately predict the observed behavior, suggesting a more complex model with more steps in the signal processing mechanism is required to predict responses to multiple stimuli.

  4. Disruption of TgPHIL1 alters specific parameters of Toxoplasma gondii motility measured in a quantitative, three-dimensional live motility assay.

    PubMed

    Leung, Jacqueline M; Rould, Mark A; Konradt, Christoph; Hunter, Christopher A; Ward, Gary E

    2014-01-01

    T. gondii uses substrate-dependent gliding motility to invade cells of its hosts, egress from these cells at the end of its lytic cycle and disseminate through the host organism during infection. The ability of the parasite to move is therefore critical for its virulence. T. gondii engages in three distinct types of gliding motility on coated two-dimensional surfaces: twirling, circular gliding and helical gliding. We show here that motility in a three-dimensional Matrigel-based environment is strikingly different, in that all parasites move in irregular corkscrew-like trajectories. Methods developed for quantitative analysis of motility parameters along the smoothed trajectories demonstrate a complex but periodic pattern of motility with mean and maximum velocities of 0.58 ± 0.07 µm/s and 2.01 ± 0.17 µm/s, respectively. To test how a change in the parasite's crescent shape might affect trajectory parameters, we compared the motility of Δphil1 parasites, which are shorter and wider than wild type, to the corresponding parental and complemented lines. Although comparable percentages of parasites were moving for all three lines, the Δphil1 mutant exhibited significantly decreased trajectory lengths and mean and maximum velocities compared to the parental parasite line. These effects were either partially or fully restored upon complementation of the Δphil1 mutant. These results show that alterations in morphology may have a significant impact on T. gondii motility in an extracellular matrix-like environment, provide a possible explanation for the decreased fitness of Δphil1 parasites in vivo, and demonstrate the utility of the quantitative three-dimensional assay for studying parasite motility.

  5. Comparison of the intrinsic disorder propensities of the RuBisCO activase enzyme from the motile and non-motile oceanic green microalgae.

    PubMed

    Sena, Lucia; Uversky, Vladimir N

    2016-01-01

    Green oceanic microalgae are efficient converters of solar energy into the biomass via the photosynthesis process, with the first step of carbon fixation in the photosynthesis being controlled by the enzyme ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO), which is a large proteinaceous machine composed of large (L, 52 kDa) and small (S, 12 kDa) subunits arranged as a L8S8 hexadecamer that catalyzes the formation of 2 phosphoglyceric acid molecules from one ribulose 1,5-bisphosphate (RuBP) molecule and one of carbon dioxide (CO2) and that is considered as the most abundant protein on Earth. The catalytic efficiency of this protein is controlled by the RuBisCO activase (RCA) that interacts with RuBisCO and promotes the CO2 entrance to the active site of RuBisCO by removing RuBP. One of the peculiar features of RCA is the presence of functional disordered tails that might play a role in RCA-RuBisCO interaction. Based on their ability to move, microalgae are grouped into 2 major class, motile and non-motile. Motile microalgae have an obvious advantage over their non-motile counterparts because of their ability to actively migrate within the water column to find the most optimal environmental conditions. We hypothesizes that the RCA could be functionally different in the non-motile and motile microalgae. To check this hypothesis, we conducted a comparative computational analysis of the RCAs from the representatives of the non-motile (Ostreococcus tauri) and motile (Tetraselmis sp. GSL018) green oceanic microalgae.

  6. Septins and Bacterial Infection

    PubMed Central

    Torraca, Vincenzo; Mostowy, Serge

    2016-01-01

    Septins, a unique cytoskeletal component associated with cellular membranes, are increasingly recognized as having important roles in host defense against bacterial infection. A role for septins during invasion of Listeria monocytogenes into host cells was first proposed in 2002. Since then, work has shown that septins assemble in response to a wide variety of invasive bacterial pathogens, and septin assemblies can have different roles during the bacterial infection process. Here we review the interplay between septins and bacterial pathogens, highlighting septins as a structural determinant of host defense. We also discuss how investigation of septin assembly in response to bacterial infection can yield insight into basic cellular processes including phagocytosis, autophagy, and mitochondrial dynamics. PMID:27891501

  7. An adenosine kinase exists in Xanthomonas campestris pathovar campestris and is involved in extracellular polysaccharide production, cell motility, and virulence.

    PubMed

    Lu, Guang-Tao; Tang, Yong-Qin; Li, Cai-Yue; Li, Rui-Fang; An, Shi-Qi; Feng, Jia-Xun; He, Yong-Qiang; Jiang, Bo-Le; Tang, Dong-Jie; Tang, Ji-Liang

    2009-06-01

    Adenosine kinase (ADK) is a purine salvage enzyme and a typical housekeeping enzyme in eukaryotes which catalyzes the phosphorylation of adenosine to form AMP. Since prokaryotes synthesize purines de novo and no endogenous ADK activity is detectable in Escherichia coli, ADK has long been considered to be rare in bacteria. To date, only two prokaryotes, both of which are gram-positive bacteria, have been reported to contain ADK. Here we report that the gram-negative bacterium Xanthomonas campestris pathovar campestris, the causal agent of black rot of crucifers, possesses a gene (designated adk(Xcc)) encoding an ADK (named ADK(Xcc)), and we demonstrate genetically that the ADK(Xcc) is involved in extracellular polysaccharide (EPS) production, cell motility, and pathogenicity of X. campestris pv. campestris. adk(Xcc) was overexpressed as a His(6)-tagged protein in E. coli, and the purified His(6)-tagged protein exhibited ADK activity. Mutation of adk(Xcc) did not affect bacterial growth in rich and minimal media but led to an accumulation of intracellular adenosine and diminutions of intracellular ADK activity and ATP level, as well as EPS. The adk(Xcc) mutant displayed significant reductions in bacterial growth and virulence in the host plant.

  8. Effects of prophylactic incisional gastropexy on markers of gastric motility in dogs as determined by use of a novel wireless motility device.

    PubMed

    Gazzola, Krista M; Nelson, Laura L; Fritz, Michele C; Clancy, Michelle R; Hauptman, Joe G

    2017-01-01

    OBJECTIVE To evaluate effects of laparoscopic-assisted incisional gastropexy (LAIG) on gastric motility in dogs by use of a wireless motility device (WMD). ANIMALS 10 healthy client-owned large or giant-breed dogs. PROCEDURES 10 dogs owned by clients interested in prophylactic LAIG were enrolled. To determine effects of LAIG on gastrointestinal motility in dogs during the nonfed state, each dog was evaluated by use of a noninvasive WMD before and > 4 weeks after LAIG. All dogs underwent LAIG, with or without concurrent elective gonadectomy. Data obtained before and after LAIG were analyzed by use of proprietary software to determine the gastric emptying time, small bowel transit time, large bowel transit time, whole bowel transit time, and motility index. RESULTS No changes in variables were detected between measurements obtained before and after prophylactic LAIG. CONCLUSIONS AND CLINICAL RELEVANCE In this study, prophylactic LAIG did not have an effect on gastrointestinal motility. The WMD was tolerated well by all dogs and appeared to be a safe and effective method for evaluating gastrointestinal motility in this population of dogs.

  9. Simultaneous optical measurements of cell motility and growth.

    PubMed

    Sridharan, Shamira; Mir, Mustafa; Popescu, Gabriel

    2011-10-01

    It has recently been shown that spatial light interference microscopy (SLIM) developed in our laboratory can be used to quantify the dry mass growth of single cells with femtogram sensitivity [M. Mir et al., Proc. Nat. Acad. Sci. 108, 32 (2011)]. Here we show that it is possible to measure the motility of single cells in conjunction with the dry mass measurements. Specifically the effect of poly-L-lysine substrate on the dry mass growth of Drosophila S2 cells is studied. By measuring the mean square displacement of single cells and clusters it is shown that cells that adhere better to the surface are unable to grow. Using such a technique it is possible to measure both growth and morphogenesis, two of the cornerstones of developmental biology.

  10. Peroral Endoscopic Myotomy for Treating Achalasia and Esophageal Motility Disorders.

    PubMed

    Youn, Young Hoon; Minami, Hitomi; Chiu, Philip Wai Yan; Park, Hyojin

    2016-01-31

    Peroral endoscopic myotomy (POEM) is the application of esophageal myotomy to the concept of natural orifice transluminal surgery (NOTES) by utilizing a submucosal tunneling method. Since the first case of POEM was performed for treating achalasia in Japan in 2008, this procedure is being more widely used by many skillful endosopists all over the world. Currently, POEM is a spotlighted, emerging treatment option for achalasia, and the indications for POEM are expanding to include long-standing, sigmoid shaped esophagus in achalasia, even previously failed endoscopic treatment or surgical myotomy, and other spastic esophageal motility disorders. Accumulating data about POEM demonstrate excellent short-term outcomes with minimal risk of major adverse events, and some existing long-term data show the efficacy of POEM to be long lasting. In this review article, we review the technical details and clinical outcomes of POEM, and discuss some considerations of POEM in special situations.

  11. Synchronization of Spontaneous Active Motility of Hair Cell Bundles

    PubMed Central

    Zhang, Tracy-Ying; Ji, Seung; Bozovic, Dolores

    2015-01-01

    Hair cells of the inner ear exhibit an active process, believed to be crucial for achieving the sensitivity of auditory and vestibular detection. One of the manifestations of the active process is the occurrence of spontaneous hair bundle oscillations in vitro. Hair bundles are coupled by overlying membranes in vivo; hence, explaining the potential role of innate bundle motility in the generation of otoacoustic emissions requires an understanding of the effects of coupling on the active bundle dynamics. We used microbeads to connect small groups of hair cell bundles, using in vitro preparations that maintain their innate oscillations. Our experiments demonstrate robust synchronization of spontaneous oscillations, with either 1:1 or multi-mode phase-locking. The frequency of synchronized oscillation was found to be near the mean of the innate frequencies of individual bundles. Coupling also led to an improved regularity of entrained oscillations, demonstrated by an increase in the quality factor. PMID:26540409

  12. Hydrogel Walkers with Electro-Driven Motility for Cargo Transport

    PubMed Central

    Yang, Chao; Wang, Wei; Yao, Chen; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2015-01-01

    In this study, soft hydrogel walkers with electro-driven motility for cargo transport have been developed via a facile mould-assisted strategy. The hydrogel walkers consisting of polyanionic poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylamide) exhibit an arc looper-like shape with two “legs” for walking. The hydrogel walkers can reversibly bend and stretch via repeated “on/off” electro-triggers in electrolyte solution. Based on such bending/stretching behaviors, the hydrogel walkers can move their two “legs” to achieve one-directional walking motion on a rough surface via repeated “on/off” electro-triggering cycles. Moreover, the hydrogel walkers loaded with very heavy cargo also exhibit excellent walking motion for cargo transport. Such hydrogel systems create new opportunities for developing electro-controlled soft systems with simple design/fabrication strategies in the soft robotic field for remote manipulation and transportation. PMID:26314786

  13. Rock `N' Rho in Outer Hair Cell Motility

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Kalinec, G.; Kalinec, F.; Billadeau, D. D.; Urrutia, R.

    2003-02-01

    RhoA, Cdc42 and Rac1, small GTPases of the Rho family, are crucial regulators of the actin cytoskeleton and mediate different types of cell motility. They also help to maintain cellular homeostasis, actively regulating the structure and mechanical properties of the cells. We investigated the expression in the guinea-pig cochlea of the serine/threonine kinase ROCK, a well-known effector of RhoA, and measured electromotile amplitude in outer hair cells (OHCs) internally perfused with C3 and Y-27632, pharmacological inhibitors of RhoA and ROCK respectively, and dominant-negative mutants of Rac1 and Cdc42. We found that a RhoA/ROCK-mediated signaling pathway is important for mechanical homeostasis of cochlear OHCs, and identified ROCK as a potential target to selectively modulate outer hair cell electromotility.

  14. Mathematics of cell motility: have we got its number?

    PubMed Central

    2010-01-01

    Mathematical and computational modeling is rapidly becoming an essential research technique complementing traditional experimental biological methods. However, lack of standard modeling methods, difficulties of translating biological phenomena into mathematical language, and differences in biological and mathematical mentalities continue to hinder the scientific progress. Here we focus on one area—cell motility—characterized by an unusually high modeling activity, largely due to a vast amount of quantitative, biophysical data, ‘modular’ character of motility, and pioneering vision of the area’s experimental leaders. In this review, after brief introduction to biology of cell movements, we discuss quantitative models of actin dynamics, protrusion, adhesion, contraction, and cell shape and movement that made an impact on the process of biological discovery. We also comment on modeling approaches and open questions. PMID:18461331

  15. Kinetics of motility-induced phase separation and swim pressure

    NASA Astrophysics Data System (ADS)

    Patch, Adam; Yllanes, David; Marchetti, M. Cristina

    2017-01-01

    Active Brownian particles (ABPs) represent a minimal model of active matter consisting of self-propelled spheres with purely repulsive interactions and rotational noise. Here we examine the pressure of ABPs in two dimensions in both closed boxes and systems with periodic boundary conditions and show that its nonmonotonic behavior with density is a general property of ABPs and is not the result of finite-size effects. We correlate the time evolution of the mean pressure towards its steady-state value with the kinetics of motility-induced phase separation. For parameter values corresponding to phase-separated steady states, we identify two dynamical regimes. The pressure grows monotonically in time during the initial regime of rapid cluster formation, overshooting its steady-state value and then quickly relaxing to it, and remains constant during the subsequent slower period of cluster coalescence and coarsening. The overshoot is a distinctive feature of active systems.

  16. Crosstalk between Muscularis Macrophages and Enteric Neurons Regulates Gastrointestinal Motility

    PubMed Central

    Muller, Paul Andrew; Koscsó, Balázs; Rajani, Gaurav Manohar; Stevanovic, Korey; Berres, Marie-Luise; Hashimoto, Daigo; Mortha, Arthur; Leboeuf, Marylene; Li, Xiu-Min; Mucida, Daniel; Stanley, E. Richard; Dahan, Stephanie; Margolis, Kara Gross; Gershon, Michael David; Merad, Miriam; Bogunovic, Milena

    2014-01-01

    SUMMARY Intestinal peristalsis is a dynamic physiologic process influenced by dietary and microbial changes. It is tightly regulated by complex cellular interactions; however, our understanding of these controls is incomplete. A distinct population of macrophages is distributed in the intestinal muscularis externa. We demonstrate that in the steady state muscularis macrophages regulate peristaltic activity of the colon. They change the pattern of smooth muscle contractions by secreting bone morphogenetic protein 2 (BMP2), which activates BMP receptor (BMPR) expressed by enteric neurons. Enteric neurons, in turn, secrete colony stimulatory factor 1 (CSF1), a growth factor required for macrophage development. Finally, stimuli from microbial commensals regulate BMP2 expression by macrophages and CSF1 expression by enteric neurons. Our findings identify a plastic, microbiota-driven, crosstalk between muscularis macrophages and enteric neurons, which controls gastrointestinal motility. PMID:25036630

  17. Langevin Dynamics Deciphers the Motility Pattern of Swimming Parasites

    NASA Astrophysics Data System (ADS)

    Zaburdaev, Vasily; Uppaluri, Sravanti; Pfohl, Thomas; Engstler, Markus; Friedrich, Rudolf; Stark, Holger

    2011-05-01

    The parasite African trypanosome swims in the bloodstream of mammals and causes the highly dangerous human sleeping sickness. Cell motility is essential for the parasite’s survival within the mammalian host. We present an analysis of the random-walk pattern of a swimming trypanosome. From experimental time-autocorrelation functions for the direction of motion we identify two relaxation times that differ by an order of magnitude. They originate from the rapid deformations of the cell body and a slower rotational diffusion of the average swimming direction. Velocity fluctuations are athermal and increase for faster cells whose trajectories are also straighter. We demonstrate that such a complex dynamics is captured by two decoupled Langevin equations that decipher the complex trajectory pattern by referring it to the microscopic details of cell behavior.

  18. Peroral Endoscopic Myotomy for Treating Achalasia and Esophageal Motility Disorders

    PubMed Central

    Youn, Young Hoon; Minami, Hitomi; Chiu, Philip Wai Yan; Park, Hyojin

    2016-01-01

    Peroral endoscopic myotomy (POEM) is the application of esophageal myotomy to the concept of natural orifice transluminal surgery (NOTES) by utilizing a submucosal tunneling method. Since the first case of POEM was performed for treating achalasia in Japan in 2008, this procedure is being more widely used by many skillful endosopists all over the world. Currently, POEM is a spotlighted, emerging treatment option for achalasia, and the indications for POEM are expanding to include long-standing, sigmoid shaped esophagus in achalasia, even previously failed endoscopic treatment or surgical myotomy, and other spastic esophageal motility disorders. Accumulating data about POEM demonstrate excellent short-term outcomes with minimal risk of major adverse events, and some existing long-term data show the efficacy of POEM to be long lasting. In this review article, we review the technical details and clinical outcomes of POEM, and discuss some considerations of POEM in special situations. PMID:26717928

  19. Curved trajectories of actin-based motility in two dimensions

    NASA Astrophysics Data System (ADS)

    Wen, Fu-Lai; Leung, Kwan-tai; Chen, Hsuan-Yi

    2012-05-01

    Recent experiments have reported fascinating geometrical trajectories for actin-based motility of bacteria Listeria monocytogenes and functionalized beads. To understand the physical mechanism for these trajectories, we constructed a phenomenological model to study the motion of an actin-propelled disk in two dimensions. In our model, the force and actin density on the surface of the disk are influenced by the translation and rotation of the disk, which in turn is induced by the asymmetric distributions of those densities. We show that this feedback can destabilize a straight trajectory, leading to circular, S-shape and other geometrical trajectories observed in the experiments through bifurcations in the distributions of the force and actin density. The relation between our model and the models for self-propelled deformable particles is emphasized and discussed.

  20. Membrane tension feedback on shape and motility of eukaryotic cells

    NASA Astrophysics Data System (ADS)

    Winkler, Benjamin; Aranson, Igor S.; Ziebert, Falko

    2016-04-01

    In the framework of a phase field model of a single cell crawling on a substrate, we investigate how the properties of the cell membrane affect the shape and motility of the cell. Since the membrane influences the cell dynamics on multiple levels and provides a nontrivial feedback, we consider the following fundamental interactions: (i) the reduction of the actin polymerization rate by membrane tension; (ii) area conservation of the cell's two-dimensional cross-section vs. conservation of the circumference (i.e. membrane inextensibility); and (iii) the contribution from the membrane's bending energy to the shape and integrity of the cell. As in experiments, we investigate two pertinent observables - the cell's velocity and its aspect ratio. We find that the most important effect is the feedback of membrane tension on the actin polymerization. Bending rigidity has only minor effects, visible mostly in dynamic reshaping events, as exemplified by collisions of the cell with an obstacle.