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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. Adhesion controls bacterial actin polymerization-based movement.

    PubMed

    Soo, Frederick S; Theriot, Julie A

    2005-11-01

    As part of its infectious life cycle, the bacterial pathogen Listeria monocytogenes propels itself through the host-cell cytoplasm by triggering the polymerization of host-cell actin near the bacterial surface, harnessing the activity of several cytoskeletal proteins used during actin-based cell crawling. To distinguish among several classes of biophysical models of actin-based bacterial movement, we used a high-throughput tracking technique to record the movement of many individual bacteria during temperature shifts. The speed of each bacterium varied strongly with temperature, closely following the Arrhenius rate law. Among bacteria, the prefactor A of the Arrhenius dependence unexpectedly varied exponentially with apparent activation energy, E(a), over a wide range (8-21 kcal/mol), reminiscent of the "rate compensation effect" of classical catalytic reactions. Average E(a) were increased for mutant bacteria deficient in binding Ena/VASP proteins and bacteria moving in diluted extract. These two effects were additive. The observed temperature and rate compensation effects are consistent with a class of simple kinetic models in which the bacterium advances through the thermally driven, cooperative breakage of groups of adhesive bonds on its surface. The estimated number of coupled adhesive bonds N on the bacterial surface varies between 10 and 40 bonds. In contrast to other models, this model correctly predicts an experimentally observed negative correlation between bacterial speed and actin gel density. The idea that speed depends on adhesion, rather than polymerization, suggests several alternative mechanisms by which known cytoskeletal regulatory proteins could control cellular movement. PMID:16251274

  3. [Mechanism of bacterial gliding motility].

    PubMed

    Nakane, Daisuke

    2015-01-01

    Bacteria have various way to move over solid surfaces, such as glass, agar, and host cell. These movements involve surface appendages including flagella, type IV pili and other "mysterious" nano-machineries. Gliding motility was a term used various surface movements by several mechanisms that have not been well understood in past few decades. However, development of visualization techniques allowed us to make much progress on their dynamics of machineries. It also provided us better understanding how bacteria move over surfaces and why bacteria move in natural environments. In this review, I will introduce recent studies on the gliding motility of Flavobacteium and Mycoplasma based on the detail observation of single cell and its motility machinery with micro-nano scales. PMID:26632217

  4. Novel mechanisms power bacterial gliding motility.

    PubMed

    Nan, Beiyan; Zusman, David R

    2016-07-01

    For many bacteria, motility is essential for survival, growth, virulence, biofilm formation and intra/interspecies interactions. Since natural environments differ, bacteria have evolved remarkable motility systems to adapt, including swimming in aqueous media, and swarming, twitching and gliding on solid and semi-solid surfaces. Although tremendous advances have been achieved in understanding swimming and swarming motilities powered by flagella, and twitching motility powered by Type IV pili, little is known about gliding motility. Bacterial gliders are a heterogeneous group containing diverse bacteria that utilize surface motilities that do not depend on traditional flagella or pili, but are powered by mechanisms that are less well understood. Recently, advances in our understanding of the molecular machineries for several gliding bacteria revealed the roles of modified ion channels, secretion systems and unique machinery for surface movements. These novel mechanisms provide rich source materials for studying the function and evolution of complex microbial nanomachines. In this review, we summarize recent findings made on the gliding mechanisms of the myxobacteria, flavobacteria and mycoplasmas. PMID:27028358

  5. 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

  6. Hydrodynamics of helical-shaped bacterial motility

    NASA Astrophysics Data System (ADS)

    Wada, Hirofumi; Netz, Roland R.

    2009-08-01

    To reveal the underlying hydrodynamic mechanism for the directed propulsion of the bacterium Spiroplasma, we formulate a coarse-grained elastic polymer model with domains of alternating helicities along the contour. Using hydrodynamic simulations and analytic arguments, we show that the propagation of helical domain walls leads to the directed propulsion of the cell body opposite to the domain-wall traveling direction. Several key features of Spiroplasma motility are reproduced by our model. We in particular show that the helical pitch angle observed for Spiroplasma meliferum, ψ=35° , is optimized for maximal swimming speed and energy-conversion efficiency. Our analytic theory based on the slender-body hydrodynamic approximation agrees very well with our numerical data demonstrating how the chirality switch propagating along the helical cell body is converted to a translational thrust for the cell body itself. We in detail consider thermal effects on the propulsion efficiency in the form of orientational fluctuations and conformational fluctuations of the helix shape. The body length dependence of the cell motility is studied numerically and compared to our approximate analytic theory. For fixed pitch angle ψ=35° , the swimming speed is maximized at a ratio of cell-body length to domain length of about 2-3, which are typical values for real cells. We also propose simple analytic arguments for an enhancement of the swimming velocity with increasing solution viscosity by taking into account the effects of transient confinement of a helical cell body in a polymeric meshwork. Comparison with a generalized theory for the swimming speed of flagellated bacteria in polymeric meshworks shows that the presence of a finite-sized bacterial head gives rise to a maximal swimming speed at a finite solution viscosity, whereas in the absence of a head the swimming speed monotonically increases with increasing viscosity.

  7. Attachment of motile bacterial cells to prealigned holed microarrays.

    PubMed

    Rozhok, Sergey; Fan, Zhifang; Nyamjav, Dorjderem; Liu, Chang; Mirkin, Chad A; Holz, Richard C

    2006-12-19

    Construction of biomotors is an exciting area of scientific research that holds great promise for the development of new technologies with broad potential applications in areas such as the energy industry and medicine. Herein, we demonstrate the fabrication of prealigned microarrays of motile Escherichia coli bacterial cells on SiOx substrates. To prepare these arrays, holed surfaces with a gold layer on the bottom of the holes were utilized. The attachment of bacteria to the holes was achieved via nonspecific interactions using poly-l-lysine hydrobromide (PLL). Our data suggest that a single motile bacterial cell can be selectively attached to an individual hole on a surface and bacterial cell binding can be controlled by altering the pH, with the greatest occupancy occurring at pH 7.8. Cells attached to hole arrays remained motile for at least 4 h. These data indicate that holed surface structures provide a promising footprint for the attachment of motile bacterial cells to form high-density site-specific functional bacterial microarrays. PMID:17154612

  8. 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. PMID:26588572

  9. Microscopic Analysis of Bacterial Motility at High Pressure

    PubMed Central

    Nishiyama, Masayoshi; Sowa, Yoshiyuki

    2012-01-01

    The bacterial flagellar motor is a molecular machine that converts an ion flux to the rotation of a helical flagellar filament. Counterclockwise rotation of the filaments allows them to join in a bundle and propel the cell forward. Loss of motility can be caused by environmental factors such as temperature, pH, and solvation. Hydrostatic pressure is also a physical inhibitor of bacterial motility, but the detailed mechanism of this inhibition is still unknown. Here, we developed a high-pressure microscope that enables us to acquire high-resolution microscopic images, regardless of applied pressures. We also characterized the pressure dependence of the motility of swimming Escherichia coli cells and the rotation of single flagellar motors. The fraction and speed of swimming cells decreased with increased pressure. At 80 MPa, all cells stopped swimming and simply diffused in solution. After the release of pressure, most cells immediately recovered their initial motility. Direct observation of the motility of single flagellar motors revealed that at 80 MPa, the motors generate torque that should be sufficient to join rotating filaments in a bundle. The discrepancy in the behavior of free swimming cells and individual motors could be due to the applied pressure inhibiting the formation of rotating filament bundles that can propel the cell body in an aqueous environment. PMID:22768943

  10. Microscopic analysis of bacterial motility at high pressure.

    PubMed

    Nishiyama, Masayoshi; Sowa, Yoshiyuki

    2012-04-18

    The bacterial flagellar motor is a molecular machine that converts an ion flux to the rotation of a helical flagellar filament. Counterclockwise rotation of the filaments allows them to join in a bundle and propel the cell forward. Loss of motility can be caused by environmental factors such as temperature, pH, and solvation. Hydrostatic pressure is also a physical inhibitor of bacterial motility, but the detailed mechanism of this inhibition is still unknown. Here, we developed a high-pressure microscope that enables us to acquire high-resolution microscopic images, regardless of applied pressures. We also characterized the pressure dependence of the motility of swimming Escherichia coli cells and the rotation of single flagellar motors. The fraction and speed of swimming cells decreased with increased pressure. At 80 MPa, all cells stopped swimming and simply diffused in solution. After the release of pressure, most cells immediately recovered their initial motility. Direct observation of the motility of single flagellar motors revealed that at 80 MPa, the motors generate torque that should be sufficient to join rotating filaments in a bundle. The discrepancy in the behavior of free swimming cells and individual motors could be due to the applied pressure inhibiting the formation of rotating filament bundles that can propel the cell body in an aqueous environment. PMID:22768943

  11. Microfabricated ratchet structures for concentrating and patterning motile bacterial cells

    NASA Astrophysics Data System (ADS)

    Yub Kim, Sang; Lee, Eun Se; Lee, Ho Jae; Lee, Se Yeon; Kuk Lee, Sung; Kim, Taesung

    2010-09-01

    We present a novel microfabricated concentrator for Escherichia coli that can be a stand-alone and self-contained microfluidic device because it utilizes the motility of cells. First of all, we characterize the motility of E. coli cells and various ratcheting structures that can guide cells to move in a desired direction in straight and circular channels. Then, we combine these ratcheting microstructures with the intrinsic tendency of cells to swim on the right side in microchannels to enhance the concentration rates up to 180 fold until the concentrators are fully filled with cells. Furthermore, we demonstrate that cells can be positioned and concentrated with a constant spacing distance on a surface, allowing spatial patterning of motile cells. These results can be applied to biosorption or biosensor devices that are powered by motile cells because they can be highly concentrated without any external mechanical and electrical energy sources. Hence, we believe that the concentrator design holds considerable potential to be applied for concentrating and patterning other motile microbes and providing a versatile structure for motility study of bacterial cells.

  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. Persistent enhancement of bacterial motility increases tumor penetration.

    PubMed

    Thornlow, Dana N; Brackett, Emily L; Gigas, Jonathan M; Van Dessel, Nele; Forbes, Neil S

    2015-11-01

    Motile bacteria can overcome the transport limitations that hinder many cancer therapies. Active bacteria can penetrate through tissue to deliver treatment to resistant tumor regions. Bacterial therapy has had limited success, however, because this motility is heterogeneous, and within a population many individuals are non-motile. In human trials, heterogeneity led to poor dispersion and incomplete tumor colonization. To address these problems, a swarm-plate selection method was developed to increase swimming velocity. Video microscopy was used to measure the velocity distribution of selected bacteria and a microfluidic tumor-on-a-chip device was used to measure penetration through tumor cell masses. Selection on swarm plates increased average velocity fourfold, from 4.9 to 18.7 μm/s (P < 0.05) and decreased the number of non-motile individuals from 51% to 3% (P < 0.05). The selected phenotype was both robust and stable. Repeating the selection process consistently increased velocity and eliminated non-motile individuals. When selected strains were cryopreserved and subcultured for 30.1 doublings, the high-motility phenotype was preserved. In the microfluidic device, selected Salmonella penetrated deeper into cell masses than unselected controls. By 10 h after inoculation, control bacteria accumulated in the front 30% of cell masses, closest to the flow channel. In contrast, selected Salmonella accumulated in the back 30% of cell masses, farthest from the channel. Selection increased the average penetration distance from 150 to 400 μm (P < 0.05). This technique provides a simple and rapid method to generate high-motility Salmonella that has increased penetration and potential for greater tumor dispersion and clinical efficacy. PMID:25976712

  14. 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

    2015-01-01

    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. PMID:25938934

  15. Preparation, Imaging, and Quantification of Bacterial Surface Motility Assays

    PubMed Central

    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.

    2015-01-01

    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. PMID:25938934

  16. 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

  17. 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.

  18. Motor-driven intracellular transport powers bacterial gliding motility.

    PubMed

    Sun, Mingzhai; Wartel, Morgane; Cascales, Eric; Shaevitz, Joshua W; Mignot, Tâm

    2011-05-01

    Protein-directed intracellular transport has not been observed in bacteria despite the existence of dynamic protein localization and a complex cytoskeleton. However, protein trafficking has clear potential uses for important cellular processes such as growth, development, chromosome segregation, and motility. Conflicting models have been proposed to explain Myxococcus xanthus motility on solid surfaces, some favoring secretion engines at the rear of cells and others evoking an unknown class of molecular motors distributed along the cell body. Through a combination of fluorescence imaging, force microscopy, and genetic manipulation, we show that membrane-bound cytoplasmic complexes consisting of motor and regulatory proteins are directionally transported down the axis of a cell at constant velocity. This intracellular motion is transmitted to the exterior of the cell and converted to traction forces on the substrate. Thus, this study demonstrates the existence of a conserved class of processive intracellular motors in bacteria and shows how these motors have been adapted to produce cell motility. PMID:21482768

  19. 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.

  20. Liquid enteral diets induce bacterial translocation by increasing cecal flora without changing intestinal motility.

    PubMed

    Haskel, Y; Udassin, R; Freund, H R; Zhang, J M; Hanani, M

    2001-01-01

    The aim of this study was to determine the contribution of intestinal motility and cecal bacterial overgrowth to liquid diet-induced bacterial translocation (BT). Three different commercially available liquid diets were offered to mice for 1 week. BT to the mesenteric lymph nodes (MLN), spleen, and liver were examined as well as cecal bacterial counts and populations, small bowel length and weight, and histopathologic changes in the ileal and jejunal mucosa. In addition, the effect of the various diets on intestinal motility was measured by the transit index of a charcoal mixture introduced into the stomach. The incidence of BT to the mesenteric lymph nodes was significantly and similarly increased (p < .05) in mice fed Vivonex (30%), Ensure (30%), and Osmolite (33%) compared with chow-fed controls (0%). Compared with chow-fed controls, all three liquid diets were associated with the development of cecal bacterial overgrowth (p < .01). There were no significant changes in the transit index for the three liquid diet groups compared with the chow-fed controls. BT to the MLN was induced by all three liquid diets tested, casting some doubts as to their role in preventing BT in clinical use. BT was associated with a statistically significant increase in cecal bacterial count but was not associated with gut motility changes in this model. In fact, no significant changes in intestinal motility were noted in all groups tested. PMID:11284471

  1. 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.

  2. 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

    2015-04-01

    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. PMID:25734420

  3. 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).

  4. Bacterial motility patterns reveal importance of exploitation over exploration in marine microhabitats. Part I: theory.

    PubMed

    Xie, Li; Wu, Xiao-Lun

    2014-10-01

    Bacteria use different motility patterns to navigate and explore natural habitats. However, how these motility patterns are selected, and what their benefits may be, are not understood. In this article, we analyze the effect of motility patterns on a cell's ability to migrate in a chemical gradient and to localize at the top of the gradient, the two most important characteristics of bacterial chemotaxis. We will focus on two motility patterns, run-tumble and run-reverse-flick, that are observed and characterized in enteric bacterium Escherichia coli and marine bacterium Vibrio alginolyticus, respectively. To make an objective comparison, master equations are developed on the basis of microscopic motions of the bacteria. An unexpected yet significant result is that by adopting the run-reverse-flick motility pattern, a bacterium can reduce its diffusivity without compromising its drift in the chemical gradient. This finding is biologically important as it suggests that the motility pattern can improve a microorganism's ability to sequester nutrients in a competitive environment. PMID:25296325

  5. Bacterial Motility Patterns Reveal Importance of Exploitation over Exploration in Marine Microhabitats. Part I: Theory

    PubMed Central

    Xie, Li; Wu, Xiao-Lun

    2014-01-01

    Bacteria use different motility patterns to navigate and explore natural habitats. However, how these motility patterns are selected, and what their benefits may be, are not understood. In this article, we analyze the effect of motility patterns on a cell’s ability to migrate in a chemical gradient and to localize at the top of the gradient, the two most important characteristics of bacterial chemotaxis. We will focus on two motility patterns, run-tumble and run-reverse-flick, that are observed and characterized in enteric bacterium Escherichia coli and marine bacterium Vibrio alginolyticus, respectively. To make an objective comparison, master equations are developed on the basis of microscopic motions of the bacteria. An unexpected yet significant result is that by adopting the run-reverse-flick motility pattern, a bacterium can reduce its diffusivity without compromising its drift in the chemical gradient. This finding is biologically important as it suggests that the motility pattern can improve a microorganism’s ability to sequester nutrients in a competitive environment. PMID:25296325

  6. 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.

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

    PubMed

    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

  8. 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

  9. 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.

  10. Motility protein interactions in the bacterial flagellar motor.

    PubMed Central

    Garza, A G; Harris-Haller, L W; Stoebner, R A; Manson, M D

    1995-01-01

    Five proteins (MotA, MotB, FliG, FliM, and FliN) have been implicated in energizing flagellar rotation in Escherichia coli and Salmonella typhimurium. One model for flagellar function envisions that MotA and MotB comprise the stator of a rotary motor and that FliG, FliM, and FliN are part of the rotor. MotA probably functions as a transmembrane proton channel, and MotB has been proposed to anchor MotA to the peptidoglycan of the cell wall. To study interactions between the Mot proteins themselves and between them and other components of the flagellar motor, we attempted to isolate extragenic suppressors of 13 dominant or partially dominant motB missense mutations. Four of these yielded suppressors, which exhibited widely varying efficiencies of suppression. The pattern of suppression was partially alleles-specific, but no suppressor seriously impaired motility in a motB+ strain. Of 20 suppressors from the original selection, 15 were characterized by DNA sequencing. Fourteen of these cause single amino acid changes in MotA. Thirteen alter residues in, or directly adjacent to, the putative periplasmic loops of MotA, and the remaining one alters a residue in the middle of the fourth predicted transmembrane helix of MotA. We conclude that the MotA and MotB proteins form a complex and that their interaction directly involves or is strongly influenced by the periplasmic loops of MotA. The 15th suppressor from the original selection and 2 motB suppressors identified during a subsequent search cause single amino acid substitutions in FliG. This finding suggests that the postulated Mot-protein complex may be in close proximity to FliG at the stator-rotor interface of the flagellar motor. Images Fig. 1 Fig. 2 PMID:7892209

  11. 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

  12. The flagellum in bacterial pathogens: For motility and a whole lot more.

    PubMed

    Chaban, Bonnie; Hughes, H Velocity; Beeby, Morgan

    2015-10-01

    The bacterial flagellum is an amazingly complex molecular machine with a diversity of roles in pathogenesis including reaching the optimal host site, colonization or invasion, maintenance at the infection site, and post-infection dispersal. Multi-megadalton flagellar motors self-assemble across the cell wall to form a reversible rotary motor that spins a helical propeller - the flagellum itself - to drive the motility of diverse bacterial pathogens. The flagellar motor responds to the chemoreceptor system to redirect swimming toward beneficial environments, thus enabling flagellated pathogens to seek out their site of infection. At their target site, additional roles of surface swimming and mechanosensing are mediated by flagella to trigger pathogenesis. Yet while these motility-related functions have long been recognized as virulence factors in bacteria, many bacteria have capitalized upon flagellar structure and function by adapting it to roles in other stages of the infection process. Once at their target site, the flagellum can assist adherence to surfaces, differentiation into biofilms, secretion of effector molecules, further penetration through tissue structures, or in activating phagocytosis to gain entry into eukaryotic cells. Next, upon onset of infection, flagellar expression must be adapted to deal with the host's immune system defenses, either by reduced or altered expression or by flagellar structural modification. Finally, after a successful growth phase on or inside a host, dispersal to new infection sites is often flagellar motility-mediated. Examining examples of all these processes from different bacterial pathogens, it quickly becomes clear that the flagellum is involved in bacterial pathogenesis for motility and a whole lot more. PMID:26541483

  13. 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 ...

  14. 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

  15. Prodigiosin inhibits motility and activates bacterial cell death revealing molecular biomarkers of programmed cell death.

    PubMed

    Darshan, N; Manonmani, H K

    2016-12-01

    The antimicrobial activity of prodigiosin from Serratia nematodiphila darsh1, a bacterial pigment was tested against few food borne bacterial pathogens Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The mode of action of prodigiosin was studied. Prodigiosin induced bactericidal activity indicating a stereotypical set of biochemical and morphological feature of Programmed cell death (PCD). PCD involves DNA fragmentation, generation of ROS, and expression of a protein with caspase-like substrate specificity in bacterial cells. Prodigiosin was observed to be internalized into bacterial cells and was localized predominantly in the membrane and the nuclear fraction, thus, facilitating intracellular trafficking and then binding of prodigiosin to the bacterial DNA. Corresponding to an increasing concentration of prodigiosin, the level of certain proteases were observed to increase in bacteria studied, thus initiating the onset of PCD. Prodigiosin at a sub-inhibitory concentration inhibits motility of pathogens. Our observations indicated that prodigiosin could be a promising antibacterial agent and could be used in the prevention of bacterial infections. PMID:27460563

  16. 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.

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

    PubMed

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

    2010-01-19

    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 A 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. PMID:20080557

  18. 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

  19. The role of bacterial motility in the survival and spread of Pseudomonas fluorescens in soil and in the attachment and colonisation of wheat roots.

    PubMed

    Turnbull, G A.; Morgan, J A.W.; Whipps, J M.; Saunders, J R.

    2001-06-01

    Motile and non-motile strains of Pseudomonas fluorescens SBW25 were constructed using different combinations of the lacZY, xylE and aph marker genes which allowed their detection and differentiation in soil, root and seed samples. The survival of motile and non-motile strains was investigated in both non-competitive and competitive assays in water and non-sterile soil. Although there was no difference between strains in water, the motile strain survived in significantly greater numbers than the non-motile strain after 21 days in soil. There was no significant difference between competitive assays, where motile and non-motile cells were co-inoculated into soil, and non-competitive assays where strains were inoculated separately. Bacterial survival decreased as matric potential increased from -224 to -17 kPa but matric potential had no significant effect on motile compared to non-motile strains. Vertical spread of both motile and non-motile strains was detected 6.4 mm from the inoculum zone after 14 days in the absence of percolating water. There was no significant difference, for either strain, in distance moved from the inoculum zone after 14, 26 or 40 days. The motile strain had a significant advantage in attachment to sterile wheat roots in both non-competitive and competitive studies. When the spatial colonisation of wheat root systems was assessed in non-sterile soil, there was no significant difference between the motile and non-motile strain from either seed or soil inoculum. However, when the whole root system was assessed as one sample unit, differences could be detected. Bacterial motility could contribute to survival in soil and the initial phase of colonisation, where attachment and movement onto the root surface are important. PMID:11377770

  20. The mysterious nature of bacterial surface (gliding) motility: A focal adhesion-based mechanism in Myxococcus xanthus.

    PubMed

    Islam, Salim T; Mignot, Tâm

    2015-10-01

    Motility of bacterial cells promotes a range of important physiological phenomena such as nutrient detection, harm avoidance, biofilm formation, and pathogenesis. While much research has been devoted to the mechanism of bacterial swimming in liquid via rotation of flagellar filaments, the mechanisms of bacterial translocation across solid surfaces are poorly understood, particularly when cells lack external appendages such as rotary flagella and/or retractile type IV pili. Under such limitations, diverse bacteria at the single-cell level are still able to "glide" across solid surfaces, exhibiting smooth translocation of the cell along its long axis. Though multiple gliding mechanisms have evolved in different bacterial classes, most remain poorly characterized. One exception is the gliding motility mechanism used by the Gram-negative social predatory bacterium Myxococcus xanthus. The available body of research suggests that M. xanthus gliding motility is mediated by trafficked multi-protein (Glt) cell envelope complexes, powered by proton-driven flagellar stator homologues (Agl). Through coupling to the substratum via polysaccharide slime, Agl-Glt assemblies can become fixed relative to the substratum, forming a focal adhesion site. Continued directional transport of slime-associated substratum-fixed Agl-Glt complexes would result in smooth forward movement of the cell. In this review, we have provided a comprehensive synthesis of the latest mechanistic and structural data for focal adhesion-mediated gliding motility in M. xanthus, with emphasis on the role of each Agl and Glt protein. Finally, we have also highlighted the possible connection between the motility complex and a new type of spore coat assembly system, suggesting that gliding and cell envelope synthetic complexes are evolutionarily linked. PMID:26520023

  1. Upregulation of STM3175 Decreases Bacterial Motility and Swine Colonization in a qseC (preB) Mutant of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inactivation of the QseC (PreB) sensor kinase decreases bacterial motility and pathogen colonization of the swine gastrointestinal tract for Salmonella enterica serovar Typhimurium (S. Typhimurium). In contrast, both the qseB [encoding the QseB (PreA) response regulator] and qseBC mutants had motil...

  2. Rapid, High-Throughput Tracking of Bacterial Motility in 3D via Phase-Contrast Holographic Video Microscopy

    PubMed Central

    Cheong, Fook Chiong; Wong, Chui Ching; Gao, YunFeng; Nai, Mui Hoon; Cui, Yidan; Park, Sungsu; Kenney, Linda J.; Lim, Chwee Teck

    2015-01-01

    Tracking fast-swimming bacteria in three dimensions can be extremely challenging with current optical techniques and a microscopic approach that can rapidly acquire volumetric information is required. Here, we introduce phase-contrast holographic video microscopy as a solution for the simultaneous tracking of multiple fast moving cells in three dimensions. This technique uses interference patterns formed between the scattered and the incident field to infer the three-dimensional (3D) position and size of bacteria. Using this optical approach, motility dynamics of multiple bacteria in three dimensions, such as speed and turn angles, can be obtained within minutes. We demonstrated the feasibility of this method by effectively tracking multiple bacteria species, including Escherichia coli, Agrobacterium tumefaciens, and Pseudomonas aeruginosa. In addition, we combined our fast 3D imaging technique with a microfluidic device to present an example of a drug/chemical assay to study effects on bacterial motility. PMID:25762336

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

    PubMed

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

    2014-01-01

    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. PMID:24806757

  4. 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.

  5. Small Intestinal Bacterial Overgrowth in Irritable Bowel Syndrome: Association with Colon Motility, Bowel Symptoms, and Psychological Distress

    PubMed Central

    Grover, Madhusudan; Kanazawa, Motoyori; Palsson, Olafur S.; Chitkara, Denesh K.; Gangarosa, Lisa M.; Drossman, Douglas A.; Whitehead, William E.

    2013-01-01

    Background Small intestinal bacterial overgrowth (SIBO) has been implicated in the pathogenesis of irritable bowel syndrome (IBS), although with significant controversy. Aims To determine the prevalence of SIBO in IBS and its association with colonic motility, bowel symptoms and psychological distress. Methods Sucrose hydrogen and methane breath tests were performed in 158 IBS and 34 healthy controls (HC). Thresholds for pain and urgency were tested by barostat in the descending colon. The motility index (MI) was calculated as the average area under the curve for all phasic contractions. Questionnaires assessed psychological distress, IBS symptom severity (IBSSS), IBS Quality of Life (IBS-QOL) and self reported bowel symptoms. Results 52/158 (32.9%) IBS patients had abnormal breath tests compared with 6/34 (17.9%) HC (χ2=0.079). SIBO (SIBO+) and Non-SIBO (SIBO−) did not differ in the prevalence of IBS-subtypes, IBS-SS, IBS-QOL and psychological distress variables. IBS had a greater post-distension increase in MI than HC, but there was no difference between SIBO+ and SIBO−. Predominant methane producers had higher urge thresholds (28.4 vs. 18.3, p<0.05) and higher baseline MI (461 vs. 301.45, p<0.05) than SIBO− IBS, and they reported more “hard or lumpy stools” when compared to predominant hydrogen producers (p<0.05) and SIBO− IBS (p< 0.05). Conclusions SIBO is unlikely to contribute significantly in the pathogenesis of IBS. Methane production is associated with constipation. PMID:18482250

  6. Bacterial Motility Measured by a Miniature Chamber for High-Pressure Microscopy

    PubMed Central

    Nishiyama, Masayoshi; Kojima, Seiji

    2012-01-01

    Hydrostatic pressure is one of the physical stimuli that characterize the environment of living matter. Many microorganisms thrive under high pressure and may even physically or geochemically require this extreme environmental condition. In contrast, application of pressure is detrimental to most life on Earth; especially to living organisms under ambient pressure conditions. To study the mechanism of how living things adapt to high-pressure conditions, it is necessary to monitor directly the organism of interest under various pressure conditions. Here, we report a miniature chamber for high-pressure microscopy. The chamber was equipped with a built-in separator, in which water pressure was properly transduced to that of the sample solution. The apparatus developed could apply pressure up to 150 MPa, and enabled us to acquire bright-field and epifluorescence images at various pressures and temperatures. We demonstrated that the application of pressure acted directly and reversibly on the swimming motility of Escherichia coli cells. The present technique should be applicable to a wide range of dynamic biological processes that depend on applied pressures. PMID:22942763

  7. Bacterial motility measured by a miniature chamber for high-pressure microscopy.

    PubMed

    Nishiyama, Masayoshi; Kojima, Seiji

    2012-01-01

    Hydrostatic pressure is one of the physical stimuli that characterize the environment of living matter. Many microorganisms thrive under high pressure and may even physically or geochemically require this extreme environmental condition. In contrast, application of pressure is detrimental to most life on Earth; especially to living organisms under ambient pressure conditions. To study the mechanism of how living things adapt to high-pressure conditions, it is necessary to monitor directly the organism of interest under various pressure conditions. Here, we report a miniature chamber for high-pressure microscopy. The chamber was equipped with a built-in separator, in which water pressure was properly transduced to that of the sample solution. The apparatus developed could apply pressure up to 150 MPa, and enabled us to acquire bright-field and epifluorescence images at various pressures and temperatures. We demonstrated that the application of pressure acted directly and reversibly on the swimming motility of Escherichia coli cells. The present technique should be applicable to a wide range of dynamic biological processes that depend on applied pressures. PMID:22942763

  8. 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.

  9. 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

  10. A Cronobacter turicensis O1 Antigen-Specific Monoclonal Antibody Inhibits Bacterial Motility and Entry into Epithelial Cells

    PubMed Central

    Lehner, Angelika; Dietrich, Richard; Kleinsteuber, Ina; Canals, Rocío; Zurfluh, Katrin; Weiner, Kerstin; Märtlbauer, Erwin

    2014-01-01

    Cronobacter turicensis is an opportunistic foodborne pathogen that can cause a rare but sometimes lethal infection in neonates. Little is known about the virulence mechanisms and intracellular lifestyle of this pathogen. In this study, we developed an IgG monoclonal antibody (MAb; MAb 2G4) that specifically recognizes the O1 antigen of C. turicensis cells. The antilipopolysaccharide antibody bound predominantly monovalently to the O antigen and reduced bacterial growth without causing cell agglutination. Furthermore, binding of the antibody to the O1 antigen of C. turicensis cells caused a significant reduction of the membrane potential which is required to energize flagellar rotation, accompanied by a decreased flagellum-based motility. These results indicate that binding of IgG to the O antigen of C. turicensis causes a direct antimicrobial effect. In addition, this feature of the antibody enabled new insight into the pathogenicity of C. turicensis. In a tissue culture infection model, pretreatment of C. turicensis with MAb 2G4 showed no difference in adhesion to human epithelial cells, whereas invasion of bacteria into Caco-2 cells was significantly inhibited. PMID:25534937

  11. Dynamics of a tightly coupled mechanism for flagellar rotation. Bacterial motility, chemiosmotic coupling, protonmotive force.

    PubMed

    Meister, M; Caplan, S R; Berg, H C

    1989-05-01

    The bacterial flagellar motor is a molecular engine that couples the flow of protons across the cytoplasmic membrane to rotation of the flagellar filament. We analyze the steady-state behavior of an explicit mechanical model in which a fixed number of protons carries the filament through one revolution. Predictions of this model are compared with experimentally determined relationships between protonmotive force, proton flux, torque, and speed. All such tightly coupled mechanisms produce the same torque when the motor is stalled but vary greatly in their behavior at high speed. The speed at zero load predicted by our model is limited by the rates of association and dissociation of protons at binding sites on the rotor and by the mobility of force generators containing transmembrane channels that interact with these sites. Our analysis suggests that more could be learned about the motor if it were driven by an externally applied torque backwards (at negative speed) or forwards at speeds greater than the zero-load speed. PMID:2720081

  12. BswR controls bacterial motility and biofilm formation in Pseudomonas aeruginosa through modulation of the small RNA rsmZ

    PubMed Central

    Wang, Chao; Ye, Fuzhou; Kumar, Veerendra; Gao, Yong-Gui; Zhang, Lian-Hui

    2014-01-01

    Pseudomonas aeruginosa relies on cell motility and ability to form biofilms to establish infections; however, the mechanism of regulation remains obscure. Here we report that BswR, a xenobiotic response element-type transcriptional regulator, plays a critical role in regulation of bacterial motility and biofilm formation in P. aeruginosa. Transcriptomic and biochemical analyses showed that BswR counteracts the repressor activity of MvaT, controls the transcription of small RNA rsmZ and regulates the biogenesis of bacterial flagella. The crystal structure of BswR was determined at 2.3 Å resolution; the monomer comprises a DNA-binding domain with a helix-turn-helix motif in the N terminus and two helices (α6 and α7) with a V-shaped arrangement in the C-terminus. In addition to the contacts between the parallel helices α5 of two monomers, the two helical extensions (α6 and α7) intertwine together to form a homodimer, which is the biological function unit. Based on the result of DNase I protection assay together with structural analysis of BswR homodimer, we proposed a BswR–DNA model, which suggests a molecular mechanism with which BswR could interact with DNA. Taken together, our results unveiled a novel regulatory mechanism, in which BswR controls the motility and biofilm formation of P. aeruginosa by modulating the transcription of small RNA rsmZ. PMID:24497189

  13. 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. PMID:25326304

  14. 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

  15. 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

  16. Effects of minimal exposures to atmospheric pressure plasma on the activity of Salmonella Typhimurium: Deactivation of bacterial motility and suppression of host-cell invasion.

    PubMed

    Park, Jin-Sung; Kim, Kijung; Han, Je-Hyun; Gweon, Bomi; Ko, Ung Hyun; Yoo, Suk Jae; Choe, Wonho; Shin, Jennifer H

    2016-09-01

    Atmospheric pressure plasma (APP) has been shown effective in sterilization by reducing the number of viable microbes during surface cleaning, food processing, or human tissue treatment. For safe conduct, the majority of previous research focused on complete abolition of microbes, which may require severe treatments. Our aim is to investigate the minimal treatment conditions necessary for effective inactivation of bacteria in such a manner that the APP treated bacteria would not be able to harm the host cells. For this, we ought to identify the objective criteria to make the bacteria dysfunctional. We choose the motile properties and the host-cell invasion capability as two measures to quantify the pathogenic state of bacteria. In this paper, we investigated how the APP treatment in a minimal dosage affects the activity of Salmonella Typhimurium. At 100 W and 15 kHz for 20 s, the APP treatment effectively suppressed active "run and tumble" type motility and induced formation of abnormally long structures. With 20 s exposure, the bacterial cells failed to cause pyroptosis in the host cells with >90% survival after 12 h of co-incubation. Our results suggest novel measures to evaluate the functional pathogenic state for identifying safe APP treatment conditions. PMID:27345896

  17. 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. PMID:26856450

  18. Biodegradation in a partially saturated sand matrix: compounding effects of water content, bacterial spatial distribution, and motility.

    PubMed

    Dechesne, Arnaud; Owsianiak, Mikołaj; Bazire, Alexis; Grundmann, Geneviève L; Binning, Philip J; Smets, Barth F

    2010-04-01

    Bacterial pesticide degraders are generally heterogeneously distributed in soils, leaving soil volumes devoid of degradation potential. This is expected to have an impact on degradation rates because the degradation of pollutant molecules in such zones will be contingent either on degraders colonizing these zones or on pollutant mass transfer to neighboring zones containing degraders. In a model system, we quantified the role exerted by water on mineralization rate in the context of a heterogeneously distributed degradation potential. Alginate beads colonized by Pseudomonas putida KT2440 were inserted at prescribed locations in sand microcosms so that the initial spatial distribution of the mineralization potential was controlled. The mineralization rate was strongly affected by the matric potential (decreasing rate with decreasing matric potential) and by the initial distribution of the degraders (more aggregated distributions being associated with lower rates). The mineralization was diffusion-limited, as confirmed with a mathematical model. In wet conditions, extensive cell dispersal was observed for the flagellated wild type and, albeit to a lesser extent, for a nonflagellated mutant, partially relieving the diffusion limitation. Dry conditions, however, sustained low mineralization rates through the combined effects of low pollutant diffusivity and limited degrader dispersal. PMID:20192168

  19. The QseB Response Regulator is Required for Decreased Bacterial Motility and Swine Colonization in a QseC Mutant of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inactivation of the QseC (PreB) sensor kinase decreases the motility of a qseC mutant compared to wild-type Salmonella enterica serovar Typhimurium (S. Typhimurium). In addition, the competitive fitness of the qseC mutant for colonization of the swine gastrointestinal tract is decreased compared to...

  20. 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

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

    2016-05-01

    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

  1. 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

  2. Attempts at validating a recombinant Flavobacterium psychrophilum gliding motility protein N as a vaccine candidate in rainbow trout, Oncorhynchus mykiss (Walbaum) against bacterial cold-water disease.

    PubMed

    Plant, Karen P; LaPatra, Scott E; Call, Douglas R; Cain, Kenneth D

    2014-09-01

    The Flavobacterium psychrophilum gliding motility N (GldN) protein was investigated to determine its ability to elicit antibody responses and provide protective immunity in rainbow trout Oncorhynchus mykiss (Walbaum). GldN was PCR-amplified, cloned into pET102/D-TOPO, and expressed in Escherichia coli. Bacteria expressing recombinant GldN (rGldN) were formalin-inactivated and injected intraperitoneally (i.p.) into rainbow trout with Freund's complete adjuvant (FCA) in four separate studies that used two different immunization protocols followed by challenge evaluations. Fish injected with E. coli only in FCA served as the control. Antibody responses to F. psychrophilum whole-cell lysates measured by ELISA were low in all four studies. Protection against F. psychrophilum challenge was observed in the first study, but not in the three following studies. The discrepancies in results obtained in the later studies are unclear but may relate to formalin treatment of the antigen preparations. Overall, it appeared that rGldN delivered i.p. as a crude formalin-killed preparation is not a consistent vaccine candidate, and more work is required. Additionally, this study illustrates the importance of conducting multiple in vivo evaluations on potential vaccine(s) before any conclusions are drawn. PMID:25053267

  3. Motility in the epsilon-proteobacteria.

    PubMed

    Beeby, Morgan

    2015-12-01

    The epsilon-proteobacteria are a widespread group of flagellated bacteria frequently associated with either animal digestive tracts or hydrothermal vents, with well-studied examples in the human pathogens of Helicobacter and Campylobacter genera. Flagellated motility is important to both pathogens and hydrothermal vent members, and a number of curious differences between the epsilon-proteobacterial and enteric bacterial motility paradigms make them worthy of further study. The epsilon-proteobacteria have evolved to swim at high speed and through viscous media that immobilize enterics, a phenotype that may be accounted for by the molecular architecture of the unusually large epsilon-proteobacterial flagellar motor. This review summarizes what is known about epsilon-proteobacterial motility and focuses on a number of recent discoveries that rationalize the differences with enteric flagellar motility. PMID:26590774

  4. 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.

  5. Actin motility: formin a SCAry tail.

    PubMed

    Alberts, Art; Way, Michael

    2011-01-11

    A new biochemical analysis has revealed that the Rickettsia bacterial protein Sca2--recently shown to be essential for virulence and actin-dependent motility--assembles actin filaments using a mechanism that functionally resembles the processive elongation tactics used by formins. PMID:21215933

  6. Uncovering the Mystery of Gliding Motility in the Myxobacteria

    PubMed Central

    Nan, Beiyan; Zusman, David R.

    2012-01-01

    Bacterial gliding motility is the smooth movement of cells on solid surfaces unaided by flagella or pili. Many diverse groups of bacteria exhibit gliding, but the mechanism of gliding motility has remained a mystery since it was first observed more than a century ago. Recent studies on the motility of Myxococcus xanthus, a soil myxobacterium, suggest a likely mechanism for gliding in this organism. About forty M. xanthus genes were shown to be involved in gliding motility, and some of their protein products were labeled and localized within cells. These studies suggest that gliding motility in M. xanthus involves large multiprotein structural complexes, regulatory proteins, and cytoskeletal filaments. In this review, we summarize recent experiments that provide the basis for this emerging view of M. xanthus motility. We also discuss alternative models for gliding. PMID:21910630

  7. Serotonin and colonic motility.

    PubMed

    Kendig, D M; Grider, J R

    2015-07-01

    The role of serotonin (5-hydroxytryptamine [5-HT]) in gastrointestinal motility has been studied for over 50 years. Most of the 5-HT in the body resides in the gut wall, where it is located in subsets of mucosal cells (enterochromaffin cells) and neurons (descending interneurons). Many studies suggest that 5-HT is important to normal and dysfunctional gut motility and drugs affecting 5-HT receptors, especially 5-HT3 and 5-HT4 receptors, have been used clinically to treat motility disorders; however, cardiovascular side effects have limited the use of these drugs. Recently studies have questioned the importance and necessity of 5-HT in general and mucosal 5-HT in particular for colonic motility. Recent evidence suggests the importance of 5-HT3 and 5-HT4 receptors for initiation and generation of one of the key colonic motility patterns, the colonic migrating motor complex (CMMC), in rat. The findings suggest that 5-HT3 and 5-HT4 receptors are differentially involved in two different types of rat CMMCs: the long distance contraction (LDC) and the rhythmic propulsive motor complex (RPMC). The understanding of the role of serotonin in colonic motility has been influenced by the specific motility pattern(s) studied, the stimulus used to initiate the motility (spontaneous vs induced), and the route of administration of drugs. All of these considerations contribute to the understanding and the controversy that continues to surround the role of serotonin in the gut. PMID:26095115

  8. Direct Upstream Motility in Escherichia coli

    PubMed Central

    Kaya, Tolga; Koser, Hur

    2012-01-01

    We provide an experimental demonstration of positive rheotaxis (rapid and continuous upstream motility) in wild-type Escherichia coli freely swimming over a surface. This hydrodynamic phenomenon is dominant below a critical shear rate and robust against Brownian motion and cell tumbling. We deduce that individual bacteria entering a flow system can rapidly migrate upstream (>20 μm/s) much faster than a gradually advancing biofilm. Given a bacterial population with a distribution of sizes and swim speeds, local shear rate near the surface determines the dominant hydrodynamic mode for motility, i.e., circular or random trajectories for low shear rates, positive rheotaxis for moderate flow, and sideways swimming at higher shear rates. Faster swimmers can move upstream more rapidly and at higher shear rates, as expected. Interestingly, we also find on average that both swim speed and upstream motility are independent of cell aspect ratio. PMID:22500751

  9. 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

  10. Pediatric intestinal motility disorders.

    PubMed

    Gfroerer, Stefan; Rolle, Udo

    2015-09-01

    Pediatric intestinal motility disorders affect many children and thus not only impose a significant impact on pediatric health care in general but also on the quality of life of the affected patient. Furthermore, some of these conditions might also have implications for adulthood. Pediatric intestinal motility disorders frequently present as chronic constipation in toddler age children. Most of these conditions are functional, meaning that constipation does not have an organic etiology, but in 5% of the cases, an underlying, clearly organic disorder can be identified. Patients with organic causes for intestinal motility disorders usually present in early infancy or even right after birth. The most striking clinical feature of children with severe intestinal motility disorders is the delayed passage of meconium in the newborn period. This sign is highly indicative of the presence of Hirschsprung disease (HD), which is the most frequent congenital disorder of intestinal motility. HD is a rare but important congenital disease and the most significant entity of pediatric intestinal motility disorders. The etiology and pathogenesis of HD have been extensively studied over the last several decades. A defect in neural crest derived cell migration has been proven as an underlying cause of HD, leading to an aganglionic distal end of the gut. Numerous basic science and clinical research related studies have been conducted to better diagnose and treat HD. Resection of the aganglionic bowel remains the gold standard for treatment of HD. Most recent studies show, at least experimentally, the possibility of a stem cell based therapy for HD. This editorial also includes rare causes of pediatric intestinal motility disorders such as hypoganglionosis, dysganglionosis, chronic intestinal pseudo-obstruction and ganglioneuromatosis in multiple endocrine metaplasia. Underlying organic pathologies are rare in pediatric intestinal motility disorders but must be recognized as early as

  11. Pediatric intestinal motility disorders

    PubMed Central

    Gfroerer, Stefan; Rolle, Udo

    2015-01-01

    Pediatric intestinal motility disorders affect many children and thus not only impose a significant impact on pediatric health care in general but also on the quality of life of the affected patient. Furthermore, some of these conditions might also have implications for adulthood. Pediatric intestinal motility disorders frequently present as chronic constipation in toddler age children. Most of these conditions are functional, meaning that constipation does not have an organic etiology, but in 5% of the cases, an underlying, clearly organic disorder can be identified. Patients with organic causes for intestinal motility disorders usually present in early infancy or even right after birth. The most striking clinical feature of children with severe intestinal motility disorders is the delayed passage of meconium in the newborn period. This sign is highly indicative of the presence of Hirschsprung disease (HD), which is the most frequent congenital disorder of intestinal motility. HD is a rare but important congenital disease and the most significant entity of pediatric intestinal motility disorders. The etiology and pathogenesis of HD have been extensively studied over the last several decades. A defect in neural crest derived cell migration has been proven as an underlying cause of HD, leading to an aganglionic distal end of the gut. Numerous basic science and clinical research related studies have been conducted to better diagnose and treat HD. Resection of the aganglionic bowel remains the gold standard for treatment of HD. Most recent studies show, at least experimentally, the possibility of a stem cell based therapy for HD. This editorial also includes rare causes of pediatric intestinal motility disorders such as hypoganglionosis, dysganglionosis, chronic intestinal pseudo-obstruction and ganglioneuromatosis in multiple endocrine metaplasia. Underlying organic pathologies are rare in pediatric intestinal motility disorders but must be recognized as early as

  12. 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.

  13. Dynamic self-assembly of motile bacteria in liquid crystals

    PubMed Central

    Mushenheim, Peter C.; Trivedi, Rishi R.; Tuson, Hannah H.

    2014-01-01

    This paper reports an investigation of dynamical behaviors of motile rod-shaped bacteria within anisotropic viscoelastic environments defined by lyotropic liquid crystals (LCs). In contrast to passive microparticles (including non-motile bacteria) that associate irreversibly in LCs via elasticity-mediated forces, we report that motile Proteus mirabilis bacteria form dynamic and reversible multi-cellular assemblies when dispersed in a lyotropic LC. By measuring the velocity of the bacteria through the LC (8.8 +/− 0.2 μm/s) and by characterizing the ordering of the LC about the rod-shaped bacteria (tangential anchoring), we conclude that the reversibility of the inter-bacterial interaction emerges from the interplay of forces generated by the flagella of the bacteria and the elasticity of the LC, both of which are comparable in magnitude (tens of pN) for motile Proteus mirabilis cells. We also measured the dissociation process, which occurs in a direction determined by the LC, to bias the size distribution of multi-cellular bacterial complexes in a population of motile Proteus mirabilis relative to a population of non-motile cells. Overall, these observations and others reported in this paper provide insight into the fundamental dynamical behaviors of bacteria in complex anisotropic environments and suggest that motile bacteria in LCs are an exciting model system for exploration of principles for the design of active materials. PMID:24652584

  14. Cell motility on nanotopography

    NASA Astrophysics Data System (ADS)

    Kimura, Masahiro; Tsai, Irene; Green, Angelo; Jacobson, Bruce; Russell, Thomas

    2003-03-01

    Cell motility is strongly influenced by the structure of the substratum. Understanding cells motility on a surface has significant applications both in vivo and in vitro applications, such as biological sensors and hip replacement. A gradient surface is used to study the effect of the lateral nanotopography on cell motility. A gradient surface is generated by block copolymer and homopolymer blends, where the concentration of the components varies uniformly across the surface. The two homopolymers phase separate on the micron scale and this length scale gradually decrease to the nanoscopic, i.e. microphase separation of the diblock, as the copolymer concentration increases. Quantitative analysis of the speed of cell migration is correlated to the lateral length scale of the surface.

  15. [Obesity and gastrointestinal motility].

    PubMed

    Lee, Joon Seong

    2006-08-01

    Gastrointestinal (GI) motility has a crucial role in the food consumption, digestion and absorption, and also controls the appetite and satiety. In obese patients, various alterations of GI motility have been investigated. The prevalence of GERD and esophageal motor disorders in obese patients are higher than those of general population. Gastric emptying of solid food is generally accelerated and fasting gastric volume especially in distal stomach is larger in obese patients without change in accommodation. Contractile activity of small intestine in fasting period is more prominent, but orocecal transit is delayed. Autonomic dysfunction is frequently demonstrated in obese patients. These findings correspond with increased appetite and delayed satiety in obese patients, but causes or results have not been confirmed. Therapeutic interventions of these altered GI motility have been developed using botulinum toxin, gastric electrical stimulation in obese patients. Novel agents targeted for GI hormone modulation (such as ghrelin and leptin) need to be developed in the near future. PMID:16929152

  16. 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.

  17. Soft micromachines with programmable motility and morphology.

    PubMed

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

    2016-01-01

    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. PMID:27447088

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. An ocular motility conundrum.

    PubMed

    McElnea, Elizabeth Margaret; Stephenson, Kirk; Lanigan, Bernie; Flitcroft, Ian

    2014-01-01

    Two siblings, an 11-year-old boy and a 7-year-old girl presented with bilateral symmetrical ptosis and limited eye movements. Having already been reviewed on a number of occasions by a variety of specialists in multiple hospital settings a diagnosis of their ocular motility disorder had remained elusive. We describe their cases, outline the differential diagnosis and review the investigations performed which were influential in finally making a diagnosis. PMID:25349186

  3. 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

  4. 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.

  5. 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

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

    PubMed

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

    2015-02-10

    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 Mg(2+). This motility requires the PhoP-activated mgtA, mgtC, and pagM genes, which specify a Mg(2+) 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 Mg(2+) media but not in low Mg(2+) liquid media. Our findings define a form of motility that allows Salmonella to scavenge nutrients and to escape toxic compounds in low Mg(2+) semisolid environments. PMID:25624475

  7. 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.

  8. 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

  9. Motility of the jejunum after proctocolectomy and ileal pouch anastomosis.

    PubMed Central

    Chaussade, S; Merite, F; Hautefeuille, M; Valleur, P; Hautefeuille, P; Couturier, D

    1989-01-01

    Proctocolectomy with ileal pouch anastomosis could modify motility of the small intestine through two mechanisms: obstruction or bacterial overgrowth. Motility of the jejunum was measured in 11 patients with ileoanal anastomosis six (n = 6), or 12 (n = 5) months after closure of the loop ileostomy. Manometric recording from the jejunum were made during fasting (four hours) and after a liquid meal (one hour). These findings were compared with those of six healthy volunteers. Motor events were classified as follows: migrating motor complex (MMC), propagated contractions, or discrete clustered contractions. All patients were investigated for bacterial overgrowth (D-glucose breath test). Only two patients had bacterial overgrowth. The frequency of MMC remained unchanged after ileo-anal anastomosis (2.83 (0.37)/four hours) compared with normal volunteers (2.81 (0.29)/four hours). During fasting, four patients had numerous propagated contractions in the jejunum. This condition was associated in two with bacterial overgrowth and in two with intubation of the reservoir. Discrete clustered contractions were found in the seven patients studied postprandially (7.6 (2.5)/h), but not in volunteers. These seven patients emptied their pouch spontaneously and bacterial overgrowth was found in only one. As this motility pattern was previously described in partial small intestinal obstruction, it is postulated that discrete clustered contractions could be the consequence of a functional obstruction as a result of anastomosis of the small intestine to the high pressure zone of the anal sphincters. Images Fig. 1 Fig. 2 PMID:2707637

  10. 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.

  11. Swimming Motility Reduces Deposition to Silica Surfaces.

    PubMed

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

    2015-09-01

    The transport and fate of bacteria in porous media is influenced by physicochemical and biological properties. This study investigated the effect of swimming motility on the attachment of cells to silica surfaces through comprehensive analysis of cell deposition in model porous media. Distinct motilities were quantified for different strains using global and cluster-based statistical analyses of microscopic images taken under no-flow condition. The wild-type, flagellated strain DJ showed strong swimming as a result of the actively swimming subpopulation whose average speed was 25.6 μm/s; the impaired swimming of strain DJ77 was attributed to the lower average speed of 17.4 μm/s in its actively swimming subpopulation; and both the nonflagellated JZ52 and chemically treated DJ cells were nonmotile. The approach and deposition of these bacterial cells were analyzed in porous media setups, including single-collector radial stagnation point flow cells (RSPF) and two-dimensional multiple-collector micromodels under well-defined hydrodynamic conditions. In RSPF experiments, both swimming and nonmotile cells moved with the flow when at a distance ≥20 μm above the collector surface. Closer to the surface, DJ cells showed both horizontal and vertical movement, limiting their contact with the surface, while chemically treated DJ cells moved with the flow to reach the surface. These results explain how wild-type swimming reduces attachment. In agreement, the deposition in micromodels was also lowest for DJ compared with those for DJ77 and JZ52. Wild-type swimming specifically reduced deposition on the upstream surfaces of the micromodel collectors. Conducted under environmentally relevant hydrodynamic conditions, the results suggest that swimming motility is an important characteristic for bacterial deposition and transport in the environment. PMID:26436254

  12. Gene expression in Pseudomonas aeruginosa swarming motility

    PubMed Central

    2010-01-01

    Background The bacterium Pseudomonas aeruginosa is capable of three types of motilities: swimming, twitching and swarming. The latter is characterized by a fast and coordinated group movement over a semi-solid surface resulting from intercellular interactions and morphological differentiation. A striking feature of swarming motility is the complex fractal-like patterns displayed by migrating bacteria while they move away from their inoculation point. This type of group behaviour is still poorly understood and its characterization provides important information on bacterial structured communities such as biofilms. Using GeneChip® Affymetrix microarrays, we obtained the transcriptomic profiles of both bacterial populations located at the tip of migrating tendrils and swarm center of swarming colonies and compared these profiles to that of a bacterial control population grown on the same media but solidified to not allow swarming motility. Results Microarray raw data were corrected for background noise with the RMA algorithm and quantile normalized. Differentially expressed genes between the three conditions were selected using a threshold of 1.5 log2-fold, which gave a total of 378 selected genes (6.3% of the predicted open reading frames of strain PA14). Major shifts in gene expression patterns are observed in each growth conditions, highlighting the presence of distinct bacterial subpopulations within a swarming colony (tendril tips vs. swarm center). Unexpectedly, microarrays expression data reveal that a minority of genes are up-regulated in tendril tip populations. Among them, we found energy metabolism, ribosomal protein and transport of small molecules related genes. On the other hand, many well-known virulence factors genes were globally repressed in tendril tip cells. Swarm center cells are distinct and appear to be under oxidative and copper stress responses. Conclusions Results reported in this study show that, as opposed to swarm center cells, tendril

  13. 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

  14. Gastrointestinal Motility Disorders in Children

    PubMed Central

    Ambartsumyan, Lusine

    2014-01-01

    The most common and challenging gastrointestinal motility disorders in children include gastroesophageal reflux disease (GERD), esophageal achalasia, gastroparesis, chronic intestinal pseudo-obstruction, and constipation. GERD is the most common gastrointestinal motility disorder affecting children and is diagnosed clinically and treated primarily with acid secretion blockade. Esophageal achalasia, a less common disorder in the pediatric patient population, is characterized by dysphagia and treated with pneumatic balloon dilation and/or esophagomyotomy. Gastroparesis and chronic intestinal pseudo-obstruction are poorly characterized in children and are associated with significant morbidity. Constipation is among the most common complaints in children and is associated with significant morbidity as well as poor quality of life. Data on epidemiology and outcomes, clinical trials, and evaluation of new diagnostic techniques are needed to better diagnose and treat gastrointestinal motility disorders in children. We present a review of the conditions and challenges related to these common gastrointestinal motility disorders in children. PMID:24799835

  15. Motility mutants of Dictyostelium discoideum

    PubMed Central

    1982-01-01

    We describe six motility mutants of Dictyostelium discoideum in this report. They were identified among a group of temperature-sensitive growth (Tsg) mutants that had been previously isolated using an enrichment for phagocytosis-defective cells. The Tsg mutants were screened for their ability to produce tracks on gold-coated cover slips, and several strains were found that were temperature-sensitive for migration in this assay. Analysis of spontaneous Tsg+ revertants of 10 migration-defective strains identified six strains that co-reverted the Tsg and track formation phenotypes. Characterization of these six strains indicated that they were defective at restrictive temperature in track formation, phagocytosis of bacteria, and pseudopodial and filopodial activity, while retaining normal rates of oxygen consumption and viability. Because they had lost this group of motile capabilities, these strains were designated motility mutants. The Tsg+ revertants of these mutants, which coordinately recovered all of the motile activities, were found at frequencies consistent with single genetic events. Analysis of the motility mutants and their revertants suggests a relationship between the motility mutations in some of these strains and genes affecting axenic growth. PMID:7118999

  16. Actin-based phagosome motility.

    PubMed

    Zhang, Fangliang; Southwick, Frederick S; Purich, Daniel L

    2002-10-01

    Despite abundant evidence of actin's involvement at the particle internalization stage of phagocytosis, little is known about whether phagosomes undergo the same type of actin-based motility as observed with endocytic vesicles or such intracellular pathogens as Listeria and Shigella. By employing video microscopy to follow the fate of latex bead-containing phagosomes within the cytoplasm of bone marrow macrophages, we have made the novel observation of actin-based phagosome motility. Immunofluorescence microscopy confirmed that phagosomes containing IgG-opsonized, bovine serum albumin (or BSA) -coated or uncoated latex beads all formed actin-rich rocket tails that persisted only during a brief, 1-2 min period of actin-based motility. Average speeds of actin-based phagosome motility were 0.13 +/- 0.06 microm/s for IgG-coated beads, 0.14 +/- 0.04 microm/s for BSA-coated beads, and 0.11+/- 0.03 microm/s for uncoated beads. Moreover, the speeds and motile-phase duration of each type of phagosome were comparable to the behavior of pinosomes [Merrifield et al., 1999: Nat. Cell Biol. 1:72-74.]. Determination of optimal conditions for observing and analyzing actin-based phagosome motility should facilitate future investigations of phagocytosis and phagosome maturation. PMID:12211106

  17. Motility is Critical for Effective Distribution and Accumulation of Bacteria in Tumor Tissue

    PubMed Central

    Toley, Bhushan J.; Forbes, Neil S.

    2016-01-01

    Motile bacteria can overcome the penetration limitations of cancer chemotherapeutics because they can actively migrate into solid tumors. Although several genera of bacteria have been shown to accumulate preferentially in tumors, the spatiotemporal dynamics of bacterial tumor colonization and their dependence on bacterial motility is not clear. For effective tumor regression, bacteria must penetrate and distribute uniformly throughout tumors. To measure these dynamics, we used an in vitro model of continuously perfused tumor tissue to mimic the delivery and systemic clearance of Salmonella typhimurium strains SL1344 and VNP20009, and Escherichia coli strains K12 and DH5α. Tissues were treated for 1 hour with 105 or 107 CFU/ml suspensions of each strain and the location and extent of bacterial accumulation was observed for 30 hours. Salmonella had 14.5 times greater average swimming speeds than E.coli and colonized tissues at 100 times lower doses than E.coli. Bacterial motility strongly correlated (R2 = 99.3%) with the extent of tissue accumulation. When inoculated at 105 CFU/ml, motile Salmonella formed colonies denser than 1010 CFU/(g-tissue) and less motile E.coli showed no detectable colonization. Based on spatio-temporal profiles and a mathematical model of motility and growth, bacterial dispersion was found to be necessary for deep penetration into tissue. Bacterial colonization caused apoptosis in tumors and apoptosis levels correlated (R2 = 98.6%) with colonization density. These results show that motility is critical for effective distribution of bacteria in tumors and is essential for designing cancer therapies that can overcome the barrier of limited tumor penetration. PMID:22193245

  18. 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

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Yan, Z.; Hilpert, M.; Bouwer, E. J.

    2014-12-01

    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.

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

    SciTech Connect

    McCaulou, D.R.

    1993-10-01

    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{degrees}C but off at 40{degrees}C. Microspheres were used to independently quantify the effects of temperature on the sticking efficiency ({alpha}), 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{degrees}C. The sticking efficiency for non-motile A0500 (4{degrees}C) was over three times that of the motile A0500 (18{degrees}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.

  3. 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

  4. Colonic motility in ulcerative colitis

    PubMed Central

    Antonelli, Elisabetta; Villanacci, Vincenzo; Baldoni, Monia; Dore, Maria Pina

    2014-01-01

    Background Inflammatory conditions affecting the gut may cause motility disturbances, and ulcerative colitis – one of the main disorders among the inflammatory bowel diseases – may display abnormal colonic motility. Aim To review the abnormalities of the large bowel in ulcerative colitis, by considering the motility, laboratory (in vitro) and pathological studies dealing with this topic. Methods A comprehensive online search of Medline and the Science Citation Index was carried out. Results Patients with ulcerative colitis frequently display colonic motor abnormalities, including lack of contractility, an increase of propulsive contractile waves, an excessive production of nitric oxide, vasoactive intestinal polypeptide nerves, interleukin 1 beta, neurotensin, tachykinins levels and the weaker action of substance P, likely related to a neuromuscular dysfunction due to the inflammatory process. Conclusions A better understanding of the pathophysiological grounds of altered colonic motility in ulcerative colitis may lead to a more in-depth knowledge of the accompanying symptoms and to better and more targeted therapeutic approaches. PMID:25452840

  5. A polymerization-based method to construct a plasmid containing clustered DNA damage and a mismatch.

    PubMed

    Takahashi, Momoko; Akamatsu, Ken; Shikazono, Naoya

    2016-10-01

    Exposure of biological materials to ionizing radiation often induces clustered DNA damage. The mutagenicity of clustered DNA damage can be analyzed with plasmids carrying a clustered DNA damage site, in which the strand bias of a replicating plasmid (i.e., the degree to which each of the two strands of the plasmid are used as the template for replication of the plasmid) can help to clarify how clustered DNA damage enhances the mutagenic potential of comprising lesions. Placement of a mismatch near a clustered DNA damage site can help to determine the strand bias, but present plasmid-based methods do not allow insertion of a mismatch at a given site in the plasmid. Here, we describe a polymerization-based method for constructing a plasmid containing clustered DNA lesions and a mismatch. The presence of a DNA lesion and a mismatch in the plasmid was verified by enzymatic treatment and by determining the relative abundance of the progeny plasmids derived from each of the two strands of the plasmid. PMID:27449134

  6. 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.

  7. 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

  8. Flagellar motility is necessary for Aeromonas hydrophila adhesion.

    PubMed

    Qin, Yingxue; Lin, Guifang; Chen, Wenbo; Xu, Xiaojin; Yan, Qingpi

    2016-09-01

    Adhesion to host surface or cells is the initial step in bacterial pathogenesis, and the adhesion mechanisms of the fish pathogenic bacteria Aeromonas hydrophila were investigated in this study. First, a mutagenesis library of A. hydrophila that contained 332 random insertion mutants was constructed via mini-Tn10 Km mutagenesis. Four mutants displayed the most attenuated adhesion. Sequence analysis revealed that the mini-Tn10 insertion sites in the four mutant strains were flgC(GenBank accession numbers KX261880), cytb4(GenBank accession numbers JN133621), rbsR(GenBank accession numbers KX261881) and flgE(GenBank accession numbers JQ974982). To further study the roles of flgC and flgE in the adhesion of A. hydrophila, some biological characteristics of the wild-type strain B11, the mutants M121 and M240, and the complemented strains C121 and C240 were investigated. The results showed that the mutation in flgC or flgE led to the flagellar motility of A. hydrophila significant reduction or abolishment. flgC was not necessary for flagellar biosynthesis but was necessary for the full motility of A. hydrophila, flgE was involved in both flagellar biosynthesis and motility. The flagellar motility is necessary for A. hydrophila to adhere to the host mucus, which suggests flagellar motility plays crucial roles in the early infection process of this bacterium. PMID:27432325

  9. Numerical Simulation of the Twitching Motility of Bacterium Crawling on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Morikawa, Ryota; Tamakoshi, Masatada; Miyakawa, Takeshi; Takasu, Masako

    A dynamics model of bacterial twitching motility is devised. A bacterial body is bound on a plane surface and driven by multiple type IV pili (TFP) which are appendages of the bacterium. The drag force following Stokes' law also applies to the bacterial body in the viscous fluid. By using the individual model, the numerical simulations are performed and the velocities and the rotational velocity of the bacterial body are investigated. From the results of the simulations, a rapid motion with rotationcalled slingshot, which was found in P. aeruginosa, is reproduced. There is a possibility that the slingshot motion may be carried out widely in many species of bacteria having TFP.

  10. Coupling actin flow, adhesion, and morphology in a computational cell motility model

    NASA Astrophysics Data System (ADS)

    Levine, Herbert

    2014-03-01

    Eukaryotic cells crawl by means of the coordinated spatiotemporal dynamics of an active polymer gel, consisting of actin, myosin and regulators thereof. Motility is necessarily coupled to shape, as the force generating mechanisms such as polymerization-based protrusions interact with the elasticity of the cell membrane and thereby determine the cell morphology. We have introduced a ``phase-field'' model of crawling cells, utilizing a mathematical approach originally developed for morphology problems arising in the field of liquid-solid phase transitions. Our model can be used to explain the pattern of traction forces applied to the substrate as well as some recent observations concerning oscillatory instabilities of cells moving on one-dimensional fiber tracks.

  11. The Shape of Motile Cells

    PubMed Central

    Mogilner, Alex; Keren, Kinneret

    2010-01-01

    Motile cells — fan-like keratocytes, hand-shaped nerve growth cones, polygonal fibroblasts, to name but a few — come in different shapes and sizes. We discuss the origins of this diversity as well as what shape tells us about the physics and biochemistry underlying cell movement. We start with geometric rules describing cell-edge kinetics that govern cell shape, followed by a discussion of the underlying biophysics; we consider actin treadmilling, actin–myosin contraction, cell-membrane deformations, adhesion, and the complex interactions between these modules, as well as their regulation by microtubules and Rho GTPases. Focusing on several different cell types, including keratocytes and fibroblasts, we discuss how dynamic cell morphology emerges from the interplay between the different motility modules and the environment. PMID:19906578

  12. Gliding Motility and Por Secretion System Genes Are Widespread among Members of the Phylum Bacteroidetes

    PubMed Central

    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. PMID:23123910

  13. Coordination of Swarming Motility, Biosurfactant Synthesis, and Biofilm Matrix Exopolysaccharide Production in Pseudomonas aeruginosa

    PubMed Central

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

    2014-01-01

    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. PMID:25172852

  14. Using laser tweezers to measure twitching motility in Neisseria.

    PubMed

    Maier, Berenike

    2005-06-01

    Dynamic properties of type IV pili are essential for their function in bacterial infection, twitching motility and gene transfer. Laser tweezers are versatile tools to study the molecular mechanism underlying pilus dynamics at the single molecule level. Recently, these optical tweezers have been used to monitor pilus elongation and retraction in vivo at a resolution of several nanometers. The force generated by type IV pili exceeds 100 pN making pili the strongest linear motors characterized to date. The study of pilus dynamics at the single molecule level sheds light on kinetics, force generation, switching and mechanics of the Neisseria gonorrhoeae pilus motor. PMID:15939360

  15. Reduced Protein Synthesis Fidelity Inhibits Flagellar Biosynthesis and Motility

    PubMed Central

    Fan, Yongqiang; Evans, Christopher R.; Ling, Jiqiang

    2016-01-01

    Accurate translation of the genetic information from DNA to protein is maintained by multiple quality control steps from bacteria to mammals. Genetic and environmental alterations have been shown to compromise translational quality control and reduce fidelity during protein synthesis. The physiological impact of increased translational errors is not fully understood. While generally considered harmful, translational errors have recently been shown to benefit cells under certain stress conditions. In this work, we describe a novel regulatory pathway in which reduced translational fidelity downregulates expression of flagellar genes and suppresses bacterial motility. Electron microscopy imaging shows that the error-prone Escherichia coli strain lacks mature flagella. Further genetic analyses reveal that translational errors upregulate expression of a small RNA DsrA through enhancing its transcription, and deleting DsrA from the error-prone strain restores motility. DsrA regulates expression of H-NS and RpoS, both of which regulate flagellar genes. We demonstrate that an increased level of DsrA in the error-prone strain suppresses motility through the H-NS pathway. Our work suggests that bacteria are capable of switching on and off the flagellar system by altering translational fidelity, which may serve as a previously unknown mechanism to improve fitness in response to environmental cues. PMID:27468805

  16. Elastic mismatch enhances cell motility

    NASA Astrophysics Data System (ADS)

    Bresler, Yony; Palmieri, Benoit; Grant, Martin

    In recent years, the study of physics phenomena in cancer has drawn considerable attention. In cancer metastasis, a soft cancer cell leaves the tumor, and must pass through the endothelium before reaching the bloodstream. Using a phase-field model we have shown that the elasticity mismatch between cells alone is sufficient to enhance the motility of thesofter cancer cell by means of bursty migration, in agreement with experiment. We will present further characterization of these behaviour, as well as new possible applications for this model.

  17. Effects of Motility and Adsorption Rate Coefficient on Transport of Bacteria through Saturated Porous Media

    PubMed Central

    Camper, Anne K.; Hayes, Jason T.; Sturman, Paul J.; Jones, Warren L.; Cunningham, Alfred B.

    1993-01-01

    Three strains of Pseudomonas fluorescens with different motility rates and adsorption rate coefficients were injected into porous-medium reactors packed with l-mm-diameter glass spheres. Cell breakthrough, time to peak concentration, tailing, and cell recovery were measured at three interstitial pore velocities (higher than, lower than, and much lower than the maximal bacterial motility rate). All experiments were done with distilled water to reduce the effects of growth and chemotaxis. Contrary to expectations, motility did not result in either early breakthrough or early time to peak concentration at flow velocities below the motility rate. Bacterial size exclusion effects were shown to affect breakthrough curve shape at the very low flow velocity, but no such effect was seen at the higher flow velocity. The tendency of bacteria to adsorb to porous-medium surfaces, as measured by adsorption rate coefficients, profoundly influenced transport characteristics. Cell recoveries were shown to be correlated with the ratio of advective to adsorptive transport in the reactors. Adsorption rate coefficients were found to be better predictors of microbial transport phenomena than individual characteristics, such as size, motility, or porous-medium hydrodynamics. PMID:16349075

  18. 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.

  19. Cyclic Diguanylate Inversely Regulates Motility and Aggregation in Clostridium difficile

    PubMed Central

    Purcell, Erin B.; McKee, Robert W.; McBride, Shonna M.; Waters, Christopher M.

    2012-01-01

    Clostridium difficile-associated disease is increasing in incidence and is costly to treat. Our understanding of how this organism senses its entry into the host and adapts for growth in the large bowel is limited. The small-molecule second messenger cyclic diguanylate (c-di-GMP) has been extensively studied in Gram-negative bacteria and has been shown to modulate motility, biofilm formation, and other processes in response to environmental signals, yet little is known about the functions of this signaling molecule in Gram-positive bacteria or in C. difficile specifically. In the current study, we investigated the function of the second messenger c-di-GMP in C. difficile. To determine the role of c-di-GMP in C. difficile, we ectopically expressed genes encoding a diguanylate cyclase enzyme, which synthesizes c-di-GMP, or a phosphodiesterase enzyme, which degrades c-di-GMP. This strategy allowed us to artificially elevate or deplete intracellular c-di-GMP, respectively, and determine that c-di-GMP represses motility in C. difficile, consistent with previous studies in Gram-negative bacteria, in which c-di-GMP has a negative effect on myriad modes of bacterial motility. Elevated c-di-GMP levels also induced clumping of C. difficile cells, which may signify that C. difficile is capable of forming biofilms in the host. In addition, we directly quantified, for the first time, c-di-GMP production in a Gram-positive bacterium. This work demonstrates the effect of c-di-GMP on the motility of a Gram-positive bacterium and on aggregation of C. difficile, which may be relevant to the function of this signaling molecule during infection. PMID:22522894

  20. 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

  1. Effect of cellular filamentation on adventurous and social gliding motility of Myxococcus xanthus

    PubMed Central

    Sun, Hong; Yang, Zhaomin; Shi, Wenyuan

    1999-01-01

    Filamentous bacterial cells often provide biological information that is not readily evident in normal-size cells. In this study, the effect of cellular filamentation on gliding motility of Myxococcus xanthus, a Gram-negative social bacterium, was investigated. Elongation of the cell body had different effects on adventurous and social motility of M. xanthus. The rate of A-motility was insensitive to cell-body elongation whereas the rate of S-motility was reduced dramatically as the cell body got longer, indicating that these two motility systems work in different ways. The study also showed that filamentous wild-type cells glide smoothly with relatively straight, long cell bodies. However, filamentous cells of certain social motility mutants showed zigzag, tangled cell bodies on a solid surface, apparently a result of a lack of coordination between different fragments within the filaments. Further genetic and biochemical analyses indicated that the uncoordinated movements of these mutant filaments were correlated with the absence of cell surface fibril materials, indicating a possible new function for fibrils. PMID:10611358

  2. Particle-based simulations of self-motile suspensions

    NASA Astrophysics Data System (ADS)

    Hinz, Denis F.; Panchenko, Alexander; Kim, Tae-Yeon; Fried, Eliot

    2015-11-01

    A simple model for simulating flows of active suspensions is investigated. The approach is based on dissipative particle dynamics. While the model is potentially applicable to a wide range of self-propelled particle systems, the specific class of self-motile bacterial suspensions is considered as a modeling scenario. To mimic the rod-like geometry of a bacterium, two dissipative particle dynamics particles are connected by a stiff harmonic spring to form an aggregate dissipative particle dynamics molecule. Bacterial motility is modeled through a constant self-propulsion force applied along the axis of each such aggregate molecule. The model accounts for hydrodynamic interactions between self-propelled agents through the pairwise dissipative interactions conventional to dissipative particle dynamics. Numerical simulations are performed using a customized version of the open-source software package LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) software package. Detailed studies of the influence of agent concentration, pairwise dissipative interactions, and Stokes friction on the statistics of the system are provided. The simulations are used to explore the influence of hydrodynamic interactions in active suspensions. For high agent concentrations in combination with dominating pairwise dissipative forces, strongly correlated motion patterns and a fluid-like spectral distributions of kinetic energy are found. In contrast, systems dominated by Stokes friction exhibit weaker spatial correlations of the velocity field. These results indicate that hydrodynamic interactions may play an important role in the formation of spatially extended structures in active suspensions.

  3. Xanthomonas citri subsp. citri type IV Pilus is required for twitching motility, biofilm development, and adherence.

    PubMed

    Dunger, German; Guzzo, Cristiane R; Andrade, Maxuel O; Jones, Jeffrey B; Farah, Chuck S

    2014-10-01

    Bacterial type IV pili (T4P) are long, flexible surface filaments that consist of helical polymers of mostly pilin subunits. Cycles of polymerization, attachment, and depolymerization mediate several pilus-dependent bacterial behaviors, including twitching motility, surface adhesion, pathogenicity, natural transformation, escape from immune system defense mechanisms, and biofilm formation. The Xanthomonas citri subsp. citri strain 306 genome codes for a large set of genes involved in T4P biogenesis and regulation and includes several pilin homologs. We show that X. citri subsp. citri can exhibit twitching motility in a manner similar to that observed in other bacteria such as Pseudomonas aeruginosa and Xylella fastidiosa and that this motility is abolished in Xanthomonas citri subsp. citri knockout strains in the genes coding for the major pilin subunit PilAXAC3241, the ATPases PilBXAC3239 and PilTXAC2924, and the T4P biogenesis regulators PilZXAC1133 and FimXXAC2398. Microscopy analyses were performed to compare patterns of bacterial migration in the wild-type and knockout strains and we observed that the formation of mushroom-like structures in X. citri subsp. citri biofilm requires a functional T4P. Finally, infection of X. citri subsp. citri cells by the bacteriophage (ΦXacm4-11 is T4P dependent. The results of this study improve our understanding of how T4P influence Xanthomonas motility, biofilm formation, and susceptibility to phage infection. PMID:25180689

  4. Link between hypothyroidism and small intestinal bacterial overgrowth.

    PubMed

    Patil, Anant D

    2014-05-01

    Altered gastrointestinal (GI) motility is seen in many pathological conditions. Reduced motility is one of the risk factors for development of a small intestinal bacterial overgrowth (SIBO). Hypothyroidism is associated with altered GI motility. The aim of this article was to study the link between hypothyroidism, altered GI motility and development of SIBO. Published literature was reviewed to study the association of altered GI motility, SIBO and hypothyroidism. Altered GI motility leads to SIBO. SIBO is common in patients with hypothyroidism. Patients with chronic GI symptoms in hypothyroidism should be evaluated for the possibility of SIBO. Both antibiotics and probiotics have been studied and found to be effective in management of SIBO. PMID:24944923

  5. Link between hypothyroidism and small intestinal bacterial overgrowth

    PubMed Central

    Patil, Anant D.

    2014-01-01

    Altered gastrointestinal (GI) motility is seen in many pathological conditions. Reduced motility is one of the risk factors for development of a small intestinal bacterial overgrowth (SIBO). Hypothyroidism is associated with altered GI motility. The aim of this article was to study the link between hypothyroidism, altered GI motility and development of SIBO. Published literature was reviewed to study the association of altered GI motility, SIBO and hypothyroidism. Altered GI motility leads to SIBO. SIBO is common in patients with hypothyroidism. Patients with chronic GI symptoms in hypothyroidism should be evaluated for the possibility of SIBO. Both antibiotics and probiotics have been studied and found to be effective in management of SIBO. PMID:24944923

  6. Physics of Bacterial Morphogenesis

    PubMed Central

    Sun, Sean X.; Jiang, Hongyuan

    2011-01-01

    Summary: Bacterial cells utilize three-dimensional (3D) protein assemblies to perform important cellular functions such as growth, division, chemoreception, and motility. These assemblies are composed of mechanoproteins that can mechanically deform and exert force. Sometimes, small-nucleotide hydrolysis is coupled to mechanical deformations. In this review, we describe the general principle for an understanding of the coupling of mechanics with chemistry in mechanochemical systems. We apply this principle to understand bacterial cell shape and morphogenesis and how mechanical forces can influence peptidoglycan cell wall growth. We review a model that can potentially reconcile the growth dynamics of the cell wall with the role of cytoskeletal proteins such as MreB and crescentin. We also review the application of mechanochemical principles to understand the assembly and constriction of the FtsZ ring. A number of potential mechanisms are proposed, and important questions are discussed. PMID:22126993

  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. Protonmotive force and motility of Bacillus subtilis.

    PubMed Central

    Shioi, J I; Imae, Y; Oosawa, F

    1978-01-01

    Motility of Bacillus subtilis was inhibited within a few minutes by a combination of valinomycin and a high concentration of potassium ions in the medium at neutral pH. Motility was restored by lowering the concentration of valinomycin or potassium ions. The valinomycin concentration necessary for motility inhibition was determined at various concentrations of potassium ions and various pH's. At pH 7.5, valinomycin of any concentration did not inhibit the motility, when the potassium ion concentration was lower than 9 mM. In the presence of 230 mM potassium ion, the motility inhibition by valinomycin was not detected at pH lower than 6.1. These results are easily explained by the idea that the motility of B. subtilis is supported by the electrochemical potential difference of the proton across the membrane, or the protonmotive force. The electrochemical potential difference necessary for motility was estimated to be about -90 mV. PMID:25261

  9. 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

  10. Motility and chemotaxis in tissue penetration of oral epithelial cell layers by Treponema denticola.

    PubMed

    Lux, R; Miller, J N; Park, N H; Shi, W

    2001-10-01

    The ability to penetrate tissue is an important virulence factor for pathogenic spirochetes. Previous studies have recognized the role of motility in allowing pathogenic spirochetes to invade tissues and migrate to sites favorable for bacterial proliferation. However, the nature of the movements, whether they are random or controlled by chemotaxis systems, has yet to be established. In this study, we addressed the role of motility and chemotaxis in tissue penetration by the periodontal disease-associated oral spirochete Treponema denticola using an oral epithelial cell line-based experimental approach. Wild-type T. denticola ATCC 35405 was found to penetrate the tissue layers effectively, whereas a nonmotile mutant was unable to overcome the tissue barrier. Interestingly, the chemotaxis mutants also showed impaired tissue penetration. A cheA mutant that is motile but lacks the central kinase of the chemotaxis pathway showed only about 2 to 3% of the wild-type penetration rate. The two known chemoreceptors of T. denticola, DmcA and DmcB, also appear to be involved in the invasion process. The dmc mutants were actively motile but exhibited reduced tissue penetration of about 30 and 10% of the wild-type behavior, respectively. These data suggest that not only motility but also chemotaxis is involved in the tissue penetration by T. denticola. PMID:11553571

  11. Motility and Chemotaxis in Tissue Penetration of Oral Epithelial Cell Layers by Treponema denticola

    PubMed Central

    Lux, Renate; Miller, James N.; Park, No-Hee; Shi, Wenyuan

    2001-01-01

    The ability to penetrate tissue is an important virulence factor for pathogenic spirochetes. Previous studies have recognized the role of motility in allowing pathogenic spirochetes to invade tissues and migrate to sites favorable for bacterial proliferation. However, the nature of the movements, whether they are random or controlled by chemotaxis systems, has yet to be established. In this study, we addressed the role of motility and chemotaxis in tissue penetration by the periodontal disease-associated oral spirochete Treponema denticola using an oral epithelial cell line-based experimental approach. Wild-type T. denticola ATCC 35405 was found to penetrate the tissue layers effectively, whereas a nonmotile mutant was unable to overcome the tissue barrier. Interestingly, the chemotaxis mutants also showed impaired tissue penetration. A cheA mutant that is motile but lacks the central kinase of the chemotaxis pathway showed only about 2 to 3% of the wild-type penetration rate. The two known chemoreceptors of T. denticola, DmcA and DmcB, also appear to be involved in the invasion process. The dmc mutants were actively motile but exhibited reduced tissue penetration of about 30 and 10% of the wild-type behavior, respectively. These data suggest that not only motility but also chemotaxis is involved in the tissue penetration by T. denticola. PMID:11553571

  12. Diffusive transport without detailed balance in motile bacteria: does microbiology need statistical physics?

    NASA Astrophysics Data System (ADS)

    Cates, M. E.

    2012-04-01

    Microbiology is the science of microbes, particularly bacteria. Many bacteria are motile: they are capable of self-propulsion. Among these, a significant class execute so-called run-and-tumble motion: they follow a fairly straight path for a certain distance, then abruptly change direction before repeating the process. This dynamics has something in common with Brownian motion (it is diffusive at large scales), and also something in contrast. Specifically, motility parameters such as the run speed and tumble rate depend on the local environment and hence can vary in space. When they do so, even if a steady state is reached, this is not generally invariant under time reversal: the principle of detailed balance, which restores the microscopic time-reversal symmetry of systems in thermal equilibrium, is mesoscopically absent in motile bacteria. This lack of detailed balance (allowed by the flux of chemical energy that drives motility) creates pitfalls for the unwary modeller. Here I review some statistical-mechanical models for bacterial motility, presenting them as a paradigm for exploring diffusion without detailed balance. I also discuss the extent to which statistical physics is useful in understanding real or potential microbiological experiments.

  13. Human follicular fluid adverses hamster spermatozoa motility.

    PubMed

    Wetzels, A; Goverde, H J; Bastiaans, L A; Rolland, R

    1989-01-01

    To determine the optimal conditions for in vitro spermatozoa vitality, human and hamster spermatozoa were incubated at 37 degrees C in T6 medium supplemented with different biologic fluids (10% v/v). The fluids tested were human serum (HUS), hamster serum (HAS), and human follicular fluid (HUF). After incubation the spermatozoa were investigated for their qualitative and quantitative motility. Human spermatozoa maintained a good vitality in all fluids tested (approximately 25% motility after 18-h incubation). The hamster spermatozoa had after an incubation of 4 h a motility of 28.4% in HUS, 14.2% in HAS, and 2.2% in HUF. The quality of the motility was also extremely low in HUF, whereas it was adequate in HUS and in HAS. The presence of species-specific substances in mammalian follicular fluid is discussed. PMID:2589906

  14. 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.

  15. [Effect of drugs on granulocyte motility].

    PubMed

    Schmidt, D; Morenz, J

    1985-01-01

    The in-vitro influence of drugs on the chemokinesis and chemotaxis of neutrophils was investigated in order to prevent additional drug-induced motility impairment of cells in cases of already existing host defense disorders and for an eventual specific treatment of motility defects. Granulocyte motility is unimpaired by penicillin, ampicillin, carbenicillin, streptomycin, nystatin, and cyclophosphamide. The chemokinesis and chemotaxis of neutrophils are inhibited by erythromycin, oxytetracycline, doxycycline, chloramphenicol, hydrocortisone, g-strophanthin, digoxin, and digitoxin and in higher concentrations also by sulfonamides, gentamycin, prednisolone, methylprednisolone, dexamethasone, and phenylbutazone. Chemotaxis is selectively or rather more inhibited than chemokinesis by amphotericin B, griseofulvin, vinblastine++, trifluoperazine, and promethazine. Granulocyte motility is, however, stimulated by ascorbic acid, potassium thiocyanate, levamisole, lithium, and metofenazate. PMID:3161313

  16. Implications of altered gastrointestinal motility in obesity.

    PubMed

    Gallagher, T K; Geoghegan, J G; Baird, A W; Winter, D C

    2007-10-01

    The onset of obesity occurs as a result of an imbalance between nutrient consumption/absorption and energy expenditure. Gastrointestinal (GI) motility plays a critical role in the rate of consumption of foods, digestion, and absorption of nutrients. Various segments of the GI tract coordinate in a complex yet precise way, to control the process of food consumption, digestion, and absorption of nutrients. GI motility not only regulates the rates at which nutrients are processed and absorbed in the gut, but also, via mechanical and neurohormonal methods, participates in the control of appetite and satiety. Altered GI motility has frequently been observed in obese patients, the significance of which is incompletely understood. However, these alterations can be considered as potential contributing factors in the development and maintenance of obesity and changed eating behavior. Therapies aimed at regulating or counteracting the observed changes in GI motility are being actively explored and applied clinically in the management of obese patients. PMID:18098402

  17. ATPases, ion exchangers and human sperm motility.

    PubMed

    Peralta-Arias, Rubén D; Vívenes, Carmen Y; Camejo, María I; Piñero, Sandy; Proverbio, Teresa; Martínez, Elizabeth; Marín, Reinaldo; Proverbio, Fulgencio

    2015-05-01

    Human sperm has several mechanisms to control its ionic milieu, such as the Na,K-ATPase (NKA), the Ca-ATPase of the plasma membrane (PMCA), the Na(+)/Ca(2) (+)-exchanger (NCX) and the Na(+)/H(+)-exchanger (NHE). On the other hand, the dynein-ATPase is the intracellular motor for sperm motility. In this work, we evaluated NKA, PMCA, NHE, NCX and dynein-ATPase activities in human sperm and investigated their correlation with sperm motility. Sperm motility was measured by Computer Assisted Semen Analysis. It was found that the NKA activity is inhibited by ouabain with two Ki (7.9 × 10(-9) and 9.8 × 10(-5) M), which is consistent with the presence of two isoforms of α subunit of the NKA in the sperm plasma membranes (α1 and α4), being α4 more sensitive to ouabain. The decrease in NKA activity is associated with a reduction in sperm motility. In addition, sperm motility was evaluated in the presence of known inhibitors of NHE, PMCA and NCX, such as amiloride, eosin, and KB-R7943, respectively, as well as in the presence of nigericin after incubation with ouabain. Amiloride, eosin and KB-R7943 significantly reduced sperm motility. Nigericin reversed the effect of ouabain and amiloride on sperm motility. Dynein-ATPase activity was inhibited by acidic pH and micromolar concentrations of Ca(2) (+). We explain our results in terms of inhibition of the dynein-ATPase in the presence of higher cytosolic H(+) and Ca(2) (+), and therefore inhibition of sperm motility. PMID:25820902

  18. How the Motility Pattern of Bacteria Affects Their Dispersal and Chemotaxis

    PubMed Central

    Taktikos, Johannes; Stark, Holger; Zaburdaev, Vasily

    2013-01-01

    Most bacteria at certain stages of their life cycle are able to move actively; they can swim in a liquid or crawl on various surfaces. A typical path of the moving cell often resembles the trajectory of a random walk. However, bacteria are capable of modifying their apparently random motion in response to changing environmental conditions. As a result, bacteria can migrate towards the source of nutrients or away from harmful chemicals. Surprisingly, many bacterial species that were studied have several distinct motility patterns, which can be theoretically modeled by a unifying random walk approach. We use this approach to quantify the process of cell dispersal in a homogeneous environment and show how the bacterial drift velocity towards the source of attracting chemicals is affected by the motility pattern of the bacteria. Our results open up the possibility of accessing additional information about the intrinsic response of the cells using macroscopic observations of bacteria moving in inhomogeneous environments. PMID:24391710

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

    PubMed Central

    Crooks, John A.; Stilwell, Matthew D.; Oliver, Piercen M.; Zhong, Zhou

    2015-01-01

    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. PMID:26285783

  20. Ghrelin family of peptides and gut motility.

    PubMed

    Asakawa, Akihiro; Ataka, Koji; Fujino, Kazunori; Chen, Chih-Yen; Kato, Ikuo; Fujimiya, Mineko; Inui, Akio

    2011-04-01

    Acyl ghrelin, des-acyl ghrelin, and obestatin are three peptides isolated from the gastrointestinal tract and encoded by the same preproghrelin gene. Three ghrelin gene products participate in modulating appetite, adipogenesis, glucose metabolism, cell proliferation, immune, sleep, memory, anxiety, cognition, and stress. We have investigated the effects of ghrelin family of peptides on fed and fasted motor activities in the stomach and duodenum of freely moving conscious rats by manometric method. Intracerebroventricular (ICV) and intravenous (IV) administration of acyl ghrelin induced fasted motor activity in the duodenum in fed rats. ICV and IV administration of des-acyl ghrelin disrupted fasted motor activity in the antrum. Changes in gastric motility induced by IV administration of des-acyl ghrelin were antagonized by ICV administration of a corticotropin-releasing factor (CRF) 2 receptor antagonist. IV administration of obestatin decreased the percentage motor index in the antrum and prolonged the time taken to return to fasted motility in the duodenum in fed rats. ICV administration of CRF 1 and 2 receptor antagonists prevented the effects of obestatin on gastroduodenal motility. Ghrelin gene products regulate feeding-associated gastroduodenal motility. Stomach may regulate various functions including gastrointestinal motility via acyl ghrelin, des-acyl ghrelin and obestatin as an endocrine organ. Increasing knowledge of the effects of ghrelin family of peptides on gastrointestinal motility could lead to innovative new therapies for functional gastrointestinal disorders. PMID:21443714

  1. 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.

  2. 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.

  3. Light Regulation of Swarming Motility in Pseudomonas syringae Integrates Signaling Pathways Mediated by a Bacteriophytochrome and a LOV Protein

    PubMed Central

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

    2013-01-01

    ABSTRACT 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. PMID:23760465

  4. Cellular Motility--Experiments on Contractile and Motile Mechanisms in the Slime Mould, Physarum Polycephalum

    ERIC Educational Resources Information Center

    Holmes, R. P.; Stewart, P. R.

    1977-01-01

    Actin and myosin have now been demonstrated to be important constituents of many eukaryotic cells. Their role is primarily that of a contractile system underlying all aspects of cellular motility. Described here is a simple experimental system to demonstrate quantitatively aspects of motility and its regulation in a slime mold. (Author/MA)

  5. Coordinated Cyclic-Di-GMP Repression of Salmonella Motility through YcgR and Cellulose

    PubMed Central

    Zorraquino, Violeta; García, Begoña; Latasa, Cristina; Echeverz, Maite; Toledo-Arana, Alejandro; Valle, Jaione

    2013-01-01

    Cyclic di-GMP (c-di-GMP) is a secondary messenger that controls a variety of cellular processes, including the switch between a biofilm and a planktonic bacterial lifestyle. This nucleotide binds to cellular effectors in order to exert its regulatory functions. In Salmonella, two proteins, BcsA and YcgR, both of them containing a c-di-GMP binding PilZ domain, are the only known c-di-GMP receptors. BcsA, upon c-di-GMP binding, synthesizes cellulose, the main exopolysaccharide of the biofilm matrix. YcgR is dedicated to c-di-GMP-dependent inhibition of motility through its interaction with flagellar motor proteins. However, previous evidences indicate that in the absence of YcgR, there is still an additional element that mediates motility impairment under high c-di-GMP levels. Here we have uncovered that cellulose per se is the factor that further promotes inhibition of bacterial motility once high c-di-GMP contents drive the activation of a sessile lifestyle. Inactivation of different genes of the bcsABZC operon, mutation of the conserved residues in the RxxxR motif of the BcsA PilZ domain, or degradation of the cellulose produced by BcsA rescued the motility defect of ΔycgR strains in which high c-di-GMP levels were reached through the overexpression of diguanylate cyclases. High c-di-GMP levels provoked cellulose accumulation around cells that impeded flagellar rotation, probably by means of steric hindrance, without affecting flagellum gene expression, exportation, or assembly. Our results highlight the relevance of cellulose in Salmonella lifestyle switching as an architectural element that is both essential for biofilm development and required, in collaboration with YcgR, for complete motility inhibition. PMID:23161026

  6. 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.

  7. 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

  8. Trimebutine as a modulator of gastrointestinal motility.

    PubMed

    Lee, Hyun-Tai; Kim, Byung Joo

    2011-06-01

    Trimebutine has been used for treatment of both hypermotility and hypomotility disorders of the gastrointestinal (GI) tract, such as irritable bowel syndrome. In this issue, Tan et al. (2011) examined the concentration-dependent dual effects of trimebutine on colonic motility in guinea pig. The authors suggested that trimebutine attenuated colonic motility mainly through the inhibition of L-type Ca(2+) channels at higher concentrations, whereas, at lower concentrations, it depolarized membrane potentials by reducing BK(ca) currents, resulting in the enhancement of the muscle contractions. Trimebutine might be a plausible modulator of GI motility, which gives an insight in developing new prokinetic agents. Further studies to elucidate the effects of trimebutine on the interstitial cells of Cajal, the pacemaker in GI muscles would promote the therapeutic benefits as a GI modulator. PMID:21725804

  9. Mechanism of shape determination in motile cells

    PubMed Central

    Keren, Kinneret; Pincus, Zachary; Allen, Greg M.; Barnhart, Erin L.; Marriott, Gerard; Mogilner, Alex; Theriot, Julie A.

    2010-01-01

    The shape of motile cells is determined by many dynamic processes spanning several orders of magnitude in space and time, from local polymerization of actin monomers at subsecond timescales to global, cell-scale geometry that may persist for hours. Understanding the mechanism of shape determination in cells has proved to be extremely challenging due to the numerous components involved and the complexity of their interactions. Here we harness the natural phenotypic variability in a large population of motile epithelial keratocytes from fish (Hypsophrys nicaraguensis) to reveal mechanisms of shape determination. We find that the cells inhabit a low-dimensional, highly correlated spectrum of possible functional states. We further show that a model of actin network treadmilling in an inextensible membrane bag can quantitatively recapitulate this spectrum and predict both cell shape and speed. Our model provides a simple biochemical and biophysical basis for the observed morphology and behaviour of motile cells. PMID:18497816

  10. Development of a Novel Method for Analyzing Pseudomonas aeruginosa Twitching Motility and Its Application to Define the AmrZ Regulon.

    PubMed

    Xu, Binjie; Wozniak, Daniel J

    2015-01-01

    Twitching motility is an important migration mechanism for the Gram-negative bacterium Pseudomonas aeruginosa. In the commonly used subsurface twitching assay, the sub-population of P. aeruginosa with active twitching motility is difficult to harvest for high-throughput studies. Here we describe the development of a novel method that allows efficient isolation of bacterial sub-populations conducting highly active twitching motility. The transcription factor AmrZ regulates multiple P. aeruginosa virulence factors including twitching motility, yet the mechanism of this activation remains unclear. We therefore set out to understand this mechanism by defining the AmrZ regulon using DNA microarrays in combination with the newly developed twitching motility method. We discovered 112 genes in the AmrZ regulon and many encode virulence factors. One gene of interest and the subsequent focus was lecB, which encodes a fucose-binding lectin. DNA binding assays revealed that AmrZ activates lecB transcription by directly binding to its promoter. The lecB gene was previously shown to be required for twitching motility in P. aeruginosa strain PAK; however, our lecB deletion had no effect on twitching motility in strain PAO1. Collectively, in this study a novel condition was developed for quantitative studies of twitching motility, under which the AmrZ regulon was defined. PMID:26309248

  11. Development of a Novel Method for Analyzing Pseudomonas aeruginosa Twitching Motility and Its Application to Define the AmrZ Regulon

    PubMed Central

    Xu, Binjie; Wozniak, Daniel J.

    2015-01-01

    Twitching motility is an important migration mechanism for the Gram-negative bacterium Pseudomonas aeruginosa. In the commonly used subsurface twitching assay, the sub-population of P. aeruginosa with active twitching motility is difficult to harvest for high-throughput studies. Here we describe the development of a novel method that allows efficient isolation of bacterial sub-populations conducting highly active twitching motility. The transcription factor AmrZ regulates multiple P. aeruginosa virulence factors including twitching motility, yet the mechanism of this activation remains unclear. We therefore set out to understand this mechanism by defining the AmrZ regulon using DNA microarrays in combination with the newly developed twitching motility method. We discovered 112 genes in the AmrZ regulon and many encode virulence factors. One gene of interest and the subsequent focus was lecB, which encodes a fucose-binding lectin. DNA binding assays revealed that AmrZ activates lecB transcription by directly binding to its promoter. The lecB gene was previously shown to be required for twitching motility in P. aeruginosa strain PAK; however, our lecB deletion had no effect on twitching motility in strain PAO1. Collectively, in this study a novel condition was developed for quantitative studies of twitching motility, under which the AmrZ regulon was defined. PMID:26309248

  12. Incidence of motile Aeromonas spp. in foods.

    PubMed

    Pin, C; Marín, M L; García, M L; Tormo, J; Selgas, M D; Casas, C

    1994-09-01

    A total of 80 food samples were purchased from local retail consumer shops and examined for the presence of motile Aeromonas spp. Of the food categories tested, poultry had the highest incidence, with 100% positive. This was followed by lamb samples, with 60% positive. Raw milk and cheese samples had very low incidence (20%). No motile Aeromonas spp. were found in pre-prepared salads. Shellfish, fish, pork and beef samples had incidences of 40%. Most of the strains isolated were Aeromonas hydrophila, and for most of the food categories, no Aeromonas caviae isolates were obtained. PMID:7873101

  13. Determining the Relative Contribution and Hierarchy of hha and qseBC in the Regulation of Flagellar Motility of Escherichia coli O157:H7

    PubMed Central

    Sharma, Vijay K.; Casey, Thomas A.

    2014-01-01

    In recent studies, we demonstrated that a deletion of hha caused increased secretion of locus of enterocyte encoded adherence proteins and reduced motility of enterohemorrhagic Escherichia coli (EHEC) O157:H7. In addition to the importance of hha in positive regulation of motility, a two-component quorum sensing pathway encoded by the qseBC genes has been shown to activate bacterial motility in response to mammalian stress hormones epinephrine and norepinephrine as well as bacterially produced autoinducer-3. In this study, we compared regulatory contribution and hierarchy of hha, a member of the Hha/YmoA family of nucleoid-associated proteins, to that of qseBC in the expression of EHEC O157:H7 motility. Since norepinephrine affects motility of EHEC O157:H7 through a qseBC-encoded two-component quorum sensing signaling, we also determined whether the hha-mediated regulation of motility is affected by norepinephrine and whether this effect is qseBC dependent. We used single (Δhha or ΔqseC) and double (Δhha ΔqseC) deletion mutants to show that hha exerts a greater positive regulatory effect in comparison to qseBC on the expression of motility by EHEC O157:H7. We also show that Hha is hierarchically superior in transcriptional regulation of motility than QseBC because transcription of qseC was significantly reduced in the hha deletion mutant compared to that in the parental and the hha-complemented mutant strains. These results suggest that hha regulates motility of EHEC O157:H7 directly as well as indirectly by controlling the transcription of qseBC. PMID:24465756

  14. 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

    2014-05-01

    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. PMID:24868489

  15. 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.

  16. Targeting tumor cell motility to prevent metastasis

    PubMed Central

    Palmer, Trenis D.; Ashby, William J.; Lewis, John D.; Zijlstra, Andries

    2011-01-01

    Mortality and morbidity in patients with solid tumors invariably results from the disruption of normal biological function caused by disseminating tumor cells. Tumor cell migration is under intense investigation as the underlying cause of cancer metastasis. The need for tumor cell motility in the progression of metastasis has been established experimentally and is supported empirically by basic and clinical research implicating a large collection of migration-related genes. However, there are few clinical interventions designed to specifically target the motility of tumor cells and adjuvant therapy to specifically prevent cancer cell dissemination is severely limited. In an attempt to define motility targets suitable for treating metastasis, we have parsed the molecular determinants of tumor cell motility into five underlying principles including cell autonomous ability, soluble communication, cell-cell adhesion, cell-matrix adhesion, and integrating these determinants of migration on molecular scaffolds. The current challenge is to implement meaningful and sustainable inhibition of metastasis by developing clinically viable disruption of molecular targets that control these fundamental capabilities. PMID:21664937

  17. 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. PMID:20054084

  18. Maintenance of motility bias during cyanobacterial phototaxis.

    PubMed

    Chau, Rosanna Man Wah; Ursell, Tristan; Wang, Shuo; Huang, Kerwyn Casey; Bhaya, Devaki

    2015-04-01

    Signal transduction in bacteria is complex, ranging across scales from molecular signal detectors and effectors to cellular and community responses to stimuli. The unicellular, photosynthetic cyanobacterium Synechocystis sp. PCC6803 transduces a light stimulus into directional movement known as phototaxis. This response occurs via a biased random walk toward or away from a directional light source, which is sensed by intracellular photoreceptors and mediated by Type IV pili. It is unknown how quickly cells can respond to changes in the presence or directionality of light, or how photoreceptors affect single-cell motility behavior. In this study, we use time-lapse microscopy coupled with quantitative single-cell tracking to investigate the timescale of the cellular response to various light conditions and to characterize the contribution of the photoreceptor TaxD1 (PixJ1) to phototaxis. We first demonstrate that a community of cells exhibits both spatial and population heterogeneity in its phototactic response. We then show that individual cells respond within minutes to changes in light conditions, and that movement directionality is conferred only by the current light directionality, rather than by a long-term memory of previous conditions. Our measurements indicate that motility bias likely results from the polarization of pilus activity, yielding variable levels of movement in different directions. Experiments with a photoreceptor (taxD1) mutant suggest a supplementary role of TaxD1 in enhancing movement directionality, in addition to its previously identified role in promoting positive phototaxis. Motivated by the behavior of the taxD1 mutant, we demonstrate using a reaction-diffusion model that diffusion anisotropy is sufficient to produce the observed changes in the pattern of collective motility. Taken together, our results establish that single-cell tracking can be used to determine the factors that affect motility bias, which can then be coupled with

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

    PubMed

    Wiles, Travis J; Jemielita, Matthew; Baker, Ryan P; Schlomann, Brandon H; Logan, Savannah L; Ganz, Julia; Melancon, Ellie; Eisen, Judith S; Guillemin, Karen; Parthasarathy, Raghuveer

    2016-07-01

    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

  20. 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

  1. Colony Expansion of Socially Motile Myxococcus xanthus Cells Is Driven by Growth, Motility, and Exopolysaccharide Production

    PubMed Central

    Patra, Pintu; Kissoon, Kimberley; Cornejo, Isabel; Kaplan, Heidi B.; Igoshin, Oleg A.

    2016-01-01

    Myxococcus xanthus, a model organism for studies of multicellular behavior in bacteria, moves exclusively on solid surfaces using two distinct but coordinated motility mechanisms. One of these, social (S) motility is powered by the extension and retraction of type IV pili and requires the presence of exopolysaccharides (EPS) produced by neighboring cells. As a result, S motility requires close cell-to-cell proximity and isolated cells do not translocate. Previous studies measuring S motility by observing the colony expansion of cells deposited on agar have shown that the expansion rate increases with initial cell density, but the biophysical mechanisms involved remain largely unknown. To understand the dynamics of S motility-driven colony expansion, we developed a reaction-diffusion model describing the effects of cell density, EPS deposition and nutrient exposure on the expansion rate. Our results show that at steady state the population expands as a traveling wave with a speed determined by the interplay of cell motility and growth, a well-known characteristic of Fisher’s equation. The model explains the density-dependence of the colony expansion by demonstrating the presence of a lag phase–a transient period of very slow expansion with a duration dependent on the initial cell density. We propose that at a low initial density, more time is required for the cells to accumulate enough EPS to activate S-motility resulting in a longer lag period. Furthermore, our model makes the novel prediction that following the lag phase the population expands at a constant rate independent of the cell density. These predictions were confirmed by S motility experiments capturing long-term expansion dynamics. PMID:27362260

  2. Development of Fluorescent Polymerization-based Signal Amplification for Sensitive and Non-enzymatic Biodetection in Antibody Microarrays

    PubMed Central

    Avens, Heather J.; Bowman, Christopher N.

    2009-01-01

    Antibody microarrays are a critical tool for proteomics, requiring broad, highly sensitive detection of numerous low abundance biomarkers. Fluorescent polymerization-based amplification (FPBA) is presented as a novel, non-enzymatic signal amplification method that takes advantage of the chain-reaction nature of radical polymerization to achieve a highly amplified fluorescent response. A streptavidin-eosin conjugate localizes eosin photoinitiators for polymerization on the chip where biotinylated target protein is bound. The chip is contacted with acrylamide as a monomer, N-methyldiethanolamine as a coinitiator and yellow/green fluorescent nanoparticles (NPs) which, upon initiation, combine to form a macroscopically visible and highly fluorescent film. The rapid polymerization kinetics and the presence of cross-linker favor entrapment of the fluorescent NPs in the polymer, enabling highly sensitive fluorescent biodetection. This method is demonstrated as being appropriate for antibody microarrays and is compared to detection approaches which utilize streptavidin-FITC (SA-FITC) and streptavidin-labeled yellow/green NPs (SA-NPs). It is found that FPBA is able to detect 0.16 (+/− 0.01) biotin-antibody/µm2 (or 40 zeptomole surface-bound target molecules), while SA-FITC has a limit of detection of 31 (+/− 1) biotin-antibody/µm2 and SA-NPs fail to achieve any significant signal under the conditions evaluated here. Further, FPBA in conjunction with fluorescent stereomicroscopy yields equal or better sensitivity compared to fluorescent detection of SA-eosin using a much more costly microarray scanner. By facilitating highly sensitive detection, FPBA is expected to enable detection of low abundance antigens and also make possible a transition towards less expensive fluorescence detection instrumentation. PMID:19508906

  3. Development of fluorescent polymerization-based signal amplification for sensitive and non-enzymatic biodetection in antibody microarrays.

    PubMed

    Avens, Heather J; Bowman, Christopher N

    2010-01-01

    Antibody microarrays are a critical tool for proteomics, requiring broad, highly sensitive detection of numerous low abundance biomarkers. Fluorescent polymerization-based amplification (FPBA) is presented as a novel, non-enzymatic signal amplification method that takes advantage of the chain-reaction nature of radical polymerization to achieve a highly amplified fluorescent response. A streptavidin-eosin conjugate localizes eosin photoinitiators for polymerization on the chip where biotinylated target protein is bound. The chip is contacted with acrylamide as a monomer, N-methyldiethanolamine as a coinitiator and yellow/green fluorescent nanoparticles (NPs) which, upon initiation, combine to form a macroscopically visible and highly fluorescent film. The rapid polymerization kinetics and the presence of cross-linker favor entrapment of the fluorescent NPs in the polymer, enabling highly sensitive fluorescent biodetection. This method is demonstrated as being appropriate for antibody microarrays and is compared to detection approaches which utilize streptavidin-fluorescein isothiocyanate (SA-FITC) and streptavidin-labeled yellow/green NPs (SA-NPs). It is found that FPBA is able to detect 0.16 + or - 0.01 biotin-antibody microm(-2) (or 40 zmol surface-bound target molecules), while SA-FITC has a limit of detection of 31 + or - 1 biotin-antibody microm(-2) and SA-NPs fail to achieve any significant signal under the conditions evaluated here. Further, FPBA in conjunction with fluorescent stereomicroscopy yields equal or better sensitivity compared to fluorescent detection of SA-eosin using a much more costly microarray scanner. By facilitating highly sensitive detection, FPBA is expected to enable detection of low abundance antigens and also make possible a transition towards less expensive fluorescence detection instrumentation. PMID:19508906

  4. 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.

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

    PubMed

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

    2014-01-01

    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. PMID:25234699

  6. 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

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

    PubMed

    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

  8. 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

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

    PubMed

    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

  10. Campylobacter jejuni pdxA Affects Flagellum-Mediated Motility to Alter Host Colonization

    PubMed Central

    Asakura, Hiroshi; Hashii, Noritaka; Uema, Masashi; Kawasaki, Nana; Sugita-Konishi, Yoshiko; Igimi, Shizunobu; Yamamoto, Shigeki

    2013-01-01

    Vitamin B6 (pyridoxal-5'-phosphate, PLP) is linked to a variety of biological functions in prokaryotes. Here, we report that the pdxA (putative 4-hydroxy-L-threonine phosphate dehydrogenase) gene plays a pivotal role in the PLP-dependent regulation of flagellar motility, thereby altering host colonization in a leading foodborne pathogen, Campylobacter jejuni. A C. jejuni pdxA mutant failed to produce PLP and exhibited a coincident loss of flagellar motility. Mass spectrometric analyses showed a 3-fold reduction in the main flagellar glycan pseudaminic acid (Pse) associated with the disruption of pdxA. The pdxA mutant also exhibited reduced growth rates compared with the WT strain. Comparative metabolomic analyses revealed differences in respiratory/energy metabolism between WT C. jejuni and the pdxA mutant, providing a possible explanation for the differential growth fitness between the two strains. Consistent with the lack of flagellar motility, the pdxA mutant showed impaired motility-mediated responses (bacterial adhesion, ERK1/2 activation, and IL-8 production) in INT407 cells and reduced colonization of chickens compared with the WT strain. Overall, this study demonstrated that the pdxA gene affects the PLP-mediated flagellar motility function, mainly through alteration of Pse modification, and the disruption of this gene also alters the respiratory/energy metabolisms to potentially affect host colonization. Our data therefore present novel implications regarding the utility of PLP and its dependent enzymes as potent target(s) for the control of this pathogen in the poultry host. PMID:23936426

  11. 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

  12. MOTILITY, AGGRESSION, AND THE BODILY I: AN INTERPRETATION OF WINNICOTT.

    PubMed

    Elkins, Jeremy

    2015-10-01

    Among the central ideas associated with the name of Winnicott, scant mention is made of motility. This is largely attributable to Winnicott himself, who never thematized motility and never wrote a paper specifically devoted to the topic. This paper suggests both that the idea of motility is nonetheless of central significance in Winnicott's thought, and that motility is of central importance in the development and constitution of the bodily I. In elaborating both these suggestions, the paper gives particular attention to the connections between motility, continuity, aggression, and creativity in Winnicott's work. PMID:26443951

  13. 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

  14. 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.

  15. Congo red uptake by motile Aeromonas species.

    PubMed

    Statner, B; George, W L

    1987-05-01

    Virulence of several species of enteropathogenic bacteria has been correlated with the ability of isolates to take up the dye Congo red. To determine whether Congo red uptake might be a useful marker for virulence of motile Aeromonas species, we examined 50 strains of diverse clinical origin on a medium containing 50 micrograms of Congo red per ml. All of the strains took up the dye to various degrees. For most strains, uptake was greatest at 37 degrees C and least at 22 degrees C. Production of acetyl methyl carbinol (Voges-Proskauer test) or lysine decarboxylase has been reported by some investigators to be a virulence marker for Aeromonas species. Congo red uptake did not correlate with either acetyl methyl carbinol or lysine decarboxylase production in our study. These data suggest that Congo red uptake may not be a useful marker for virulence of motile Aeromonas species. PMID:3584422

  16. 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.

  17. 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.

  18. FleQ coordinates flagellum-dependent and -independent motilities in Pseudomonas syringae pv. tomato DC3000.

    PubMed

    Nogales, Joaquina; Vargas, Paola; Farias, Gabriela A; Olmedilla, Adela; Sanjuán, Juan; Gallegos, María-Trinidad

    2015-11-01

    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

  19. 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

  20. New aspects in the biology of Photobacterium damselae subsp. piscicida: pili, motility and adherence to solid surfaces.

    PubMed

    Remuzgo-Martínez, Sara; Lázaro-Díez, María; Padilla, Daniel; Vega, Belinda; El Aamri, Fátima; Icardo, José Manuel; Acosta, Félix; Ramos-Vivas, José

    2014-11-01

    We describe for the first time the presence of pilus-like structures on the surface of Photobacterium damselae subsp. piscicida (Phdp). The hint to this discovery was the ability of one strain to hemagglutinate human erythrocytes. Further analysis of several Phdp strains ultrastructure by electron microscopy revealed the presence of long, thin fibers, similar to pili of other Gram-negative bacteria. These appendages were also observed and photographed by scanning, transmission electron microscopy and immunofluorescence. Although this fish pathogen has been described as non-motile, all strains tested exhibit twitching motility, a flagella-independent type IV-dependent form of bacterial translocation over surfaces. As far as we are aware, the movement of Phdp bacteria on semi-solid or solid surfaces has not been described previously. Moreover, we speculate that Phdp twitching motility may be involved in biofilm formation. Microscopic examination of Phdp biofilms by microscopy revealed that Phdp biofilm architecture display extensive cellular chaining and also bacterial mortality during biofilm formation in vitro. Based on our results, standardized analyses of Phdp surface appendages, biofilms, motility and their impact on Phdp survival, ecology and pathobiology are now feasible. PMID:25263496

  1. Esophageal motility abnormalities in gastroesophageal reflux disease

    PubMed Central

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

    2014-01-01

    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. PMID:24868489

  2. [Gastrointestinal motility and possibilities of influencing it].

    PubMed

    Duris, I; Payer, J; Huorka, M; Randus, V; Ondrejka, P

    1994-06-01

    The authors discuss factors which influence the motility of the smooth muscles in the pancreatobiliary region. They investigated some clinical and laboratory parameters after administration of the selective antagonist of calcium influx-Pineverium bromide-Dicetel. The drug influenced significantly in a positive way nausea, flatulence, pain and chronically elevated amylases. The authors mention a cycle of possible neurohumoral changes with which specific calcium channel antagonists could interfere. PMID:8073641

  3. 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. PMID:26812683

  4. 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

  5. Bacteria motility at oil-water interfaces

    NASA Astrophysics Data System (ADS)

    Juarez, Gabriel; Smirga, Steven; Fernandez, Vicente; Stocker, Roman

    2012-11-01

    The swimming dynamics of bacteria are strongly influenced by interfaces: Motile bacteria often accumulate at rigid boundaries, such as liquid-solid interfaces, and at soft boundaries, such as liquid-air or liquid-liquid interfaces. Attachment of bacteria to these interfaces is crucial for the formation of biofilms (liquid-solid), pellicles (liquid-air), and oil-degrading communities (liquid-liquid). We investigated the motility of the oil-degrading bacteria Marinobacter aquaeolei in the presence of oil droplets. We created individual oil droplets using dedicated microfluidic devices and captured the swimming behavior of individual bacteria near the interface and their attachment dynamics to the droplets with high-speed and epifluorescent microscopy. We find that Marinobacter aquaeolei has a high affinity towards interfaces and their swimming dynamics at soft interfaces differ from both those in the bulk and at rigid boundaries. Characterizing the interaction and attachment of motile bacteria to liquid-liquid interfaces will promote a fundamental understanding to oil-microbe interactions in aquatic environments and potentially lead to improved oil bioremediation strategies.

  6. Drosophila sperm motility in the reproductive tract.

    PubMed

    Yang, Yong; Lu, Xiangyi

    2011-05-01

    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

  7. 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.

  8. 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.

  9. 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

  10. Bacterial Proteasomes

    PubMed Central

    Jastrab, Jordan B.; Darwin, K. Heran

    2015-01-01

    Interest in bacterial proteasomes was sparked by the discovery that proteasomal degradation is required for the pathogenesis of Mycobacterium tuberculosis, one of the world's deadliest pathogens. Although bacterial proteasomes are structurally similar to their eukaryotic and archaeal homologs, there are key differences in their mechanisms of assembly, activation, and substrate targeting for degradation. In this article, we compare and contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss recent advances in our understanding of how bacterial proteasomes function to influence microbial physiology. PMID:26488274

  11. 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

  12. 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

  13. 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.

  14. 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. PMID:26465495

  15. 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

  16. 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. PMID:26908282

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

    PubMed

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

    2014-01-01

    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. PMID:25323771

  18. 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

  19. Plant Natural Products Targeting Bacterial Virulence Factors.

    PubMed

    Silva, Laura Nunes; Zimmer, Karine Rigon; Macedo, Alexandre José; Trentin, Danielle Silva

    2016-08-24

    Decreased antimicrobial efficiency has become a global public health issue. The paucity of new antibacterial drugs is evident, and the arsenal against infectious diseases needs to be improved urgently. The selection of plants as a source of prototype compounds is appropriate, since plant species naturally produce a wide range of secondary metabolites that act as a chemical line of defense against microorganisms in the environment. Although traditional approaches to combat microbial infections remain effective, targeting microbial virulence rather than survival seems to be an exciting strategy, since the modulation of virulence factors might lead to a milder evolutionary pressure for the development of resistance. Additionally, anti-infective chemotherapies may be successfully achieved by combining antivirulence and conventional antimicrobials, extending the lifespan of these drugs. This review presents an updated discussion of natural compounds isolated from plants with chemically characterized structures and activity against the major bacterial virulence factors: quorum sensing, bacterial biofilms, bacterial motility, bacterial toxins, bacterial pigments, bacterial enzymes, and bacterial surfactants. Moreover, a critical analysis of the most promising virulence factors is presented, highlighting their potential as targets to attenuate bacterial virulence. The ongoing progress in the field of antivirulence therapy may therefore help to translate this promising concept into real intervention strategies in clinical areas. PMID:27437994

  20. Motile responses in outer hair cells.

    PubMed

    Zenner, H P

    1986-01-01

    Motile responses of cochlear hair cells open new perspectives for the understanding of cochlear hearing mechanisms and hearing disorders located in hair cells. Direct visualization of hair cell motility was achieved by a method for the study of living isolated mammalian outer hair cells (OHCs) which has overcome some of the complexities in dealing with the heterogeneous organ of Corti. Electrophysiological giga-seal whole-cell recordings of single OHC prepared by this approach had revealed negative cell potentials ranging from -32 mV to -70 mV (Gitter et al. (1986) Oto-Rhino-Laryngol. in press). Elucidation of HC motility has come from two lines of experiments. One follows from the observation that exposure of the lateral and basal membrane parts of living OHCs to increasing bath K+ concentrations resulted in a sustained reversible depolarization of the cell. Here, we report that by depolarization of the cell membrane in the presence of 25-125 mM K+/Cl- a sustained contraction of OHC was induced. This was followed by relaxation in the presence of artificial perilymph containing 5.4 mM K+/Cl-. By alternating these procedures OHCs were made to undergo as many as five cycles of contraction and relaxation. External Ca2+ was not required for the initial contraction but was essential for relaxation. Following repeated contraction/relaxation cycles the cytoplasm of individual OHCs exhibited a filamentous network, correlating with a new infracuticular anti-actin binding capacity. The second series of experiments originates in the observation that permeabilized OHCs contracted in the presence of ATP. No response was seen in the presence of control nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3733547

  1. 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. PMID:11298288

  2. 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. PMID:25956244

  3. 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

    2016-01-01

    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

  4. 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

  5. The unique paradigm of spirochete motility and chemotaxis

    PubMed Central

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

    2013-01-01

    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 helically shaped PFs allow the spirochete to swim by generating backward-moving waves by rotation. Exciting advances using cryoelectron microscopy 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. PMID:22994496

  6. Filling an Emulsion Drop with Motile Bacteria

    NASA Astrophysics Data System (ADS)

    Vladescu, I. D.; Marsden, E. J.; Schwarz-Linek, J.; Martinez, V. A.; Arlt, J.; Morozov, A. N.; Marenduzzo, D.; Cates, M. E.; Poon, W. C. K.

    2014-12-01

    We have measured the spatial distribution of motile Escherichia coli inside spherical water droplets emulsified in oil. At low cell concentrations, the cell density peaks at the water-oil interface; at increasing concentration, the bulk of each droplet fills up uniformly while the surface peak remains. Simulations and theory show that the bulk density results from a "traffic" of cells leaving the surface layer, increasingly due to cell-cell scattering as the surface coverage rises above ˜10 %. Our findings show similarities with the physics of a rarefied gas in a spherical cavity with attractive walls.

  7. 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.

  8. Regulation of axonemal motility in demembranated equine sperm.

    PubMed

    Loux, Shavahn C; Macías-Garcia, Beatríz; González-Fernández, Lauro; Canesin, Heloisa DeSiqueira; Varner, Dickson D; Hinrichs, Katrin

    2014-12-01

    Equine in vitro fertilization is not yet successful because equine sperm do not effectively capacitate in vitro. Results of previous studies suggest that this may be due to failure of induction of hyperactivated motility in equine sperm under standard capacitating conditions. To evaluate factors directly affecting axonemal motility in equine sperm, we developed a demembranated sperm model and analyzed motility parameters in this model under different conditions using computer-assisted sperm analysis. Treatment of ejaculated equine sperm with 0.02% Triton X-100 for 30 sec maximized both permeabilization and total motility after reactivation. The presence of ATP was required for motility of demembranated sperm after reactivation, but cAMP was not. The calculated intracellular pH of intact equine sperm was 7.14 ± 0.07. Demembranated sperm showed maximal total motility at pH 7. Neither increasing pH nor increasing calcium levels, nor any interaction of the two, induced hyperactivated motility in demembranated equine sperm. Motility of demembranated sperm was maintained at free calcium concentrations as low as 27 pM, and calcium arrested sperm motility at much lower concentrations than those reported in other species. Calcium arrest of sperm motility was not accompanied by flagellar curvature, suggesting a failure of calcium to induce the tonic bend seen in other species and thought to support hyperactivated motility. This indicated an absence, or difference in calcium sensitivity, of the related asymmetric doublet-sliding proteins. These studies show a difference in response to calcium of the equine sperm axoneme to that reported in other species that may be related to the failure of equine sperm to penetrate oocytes in vitro under standard capacitating conditions. Further work is needed to determine the factors that stimulate hyperactivated motility at the axonemal level in equine sperm. PMID:25339104

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities.

    PubMed

    Singh, Nischal; Shetye, Gauri S; Zheng, Hewen; Sun, Jiayue; Luk, Yan-Yeung

    2016-01-01

    Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration-dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities. PMID:26511780

  14. Regulation of macrophage motility by Irgm1

    PubMed Central

    Henry, Stanley C.; Traver, Maria; Daniell, Xiaojou; Indaram, Maanasa; Oliver, Tim; Taylor, Gregory A.

    2010-01-01

    IRG are a family of IFN-regulated proteins that are critical for resistance to infection. Mouse IRG proteins are divided into GMS and GKS subfamilies, based on a sequence within the G1 GTP-binding motif. The GMS proteins have a particularly profound impact on immunity, as typified by Irgm1, of which absence leads to a complete loss of resistance to a variety of intracellular bacteria and protozoa. The underlying molecular and cellular mechanisms are not clear. Here, we use time-lapse microscopy and cell-tracking analysis to demonstrate that Irgm1 is required for motility of IFN-γ-activated macrophages. The absence of Irgm1 led to decreased actin remodeling at the leading edge of migrating macrophages, as well as decreased Rac activation. Although Irgm1 did not localize to the leading edge of migrating macrophages, it was found to regulate the localization of a GKS IRG protein, Irgb6, which in turn, concentrated on the plasma membrane in the advancing lamellipodia, in close apposition to molecular components that regulate membrane remodeling, including Rac, paxillin, and actin. Thus, Irgm1 likely controls macrophage motility by regulating the positioning of specific GKS IRG proteins to the plasma membrane, which in turn, modulate cytoskeletal remodeling and membrane dynamics. PMID:19920210

  15. Gastrointestinal motility and functional gastrointestinal diseases.

    PubMed

    Kusano, Motoyasu; Hosaka, Hiroko; Kawada, Akiyo; Kuribayashi, Shiko; Shimoyama, Yasuyuki; Zai, Hiroaki; Kawamura, Osamu; Yamada, Masanobu

    2014-01-01

    Digestive tract motility patterns are closely related to the pathophysiology of functional gastrointestinal diseases (FGID), and these patterns differ markedly between the interdigestive period and the postprandial period. The characteristic motility pattern in the interdigestive period is so-called interdigestive migrating contraction (IMC). IMCs have a housekeeping role in the intestinal tract, and could also be related to FGID. IMCs arising from the stomach are called gastrointestinal IMCs (GI-IMC), while IMCs arising from the duodenum without associated gastric contractions are called intestinal IMCs (I-IMC). It is thought that I-IMCs are abnormal in FGID. Transport of food residue to the duodenum via gastric emptying is one of the most important postprandial functions of the stomach. In patients with functional dyspepsia (FD), abnormal gastric emptying is a possible mechanism of gastric dysfunction. Accordingly, delayed gastric emptying has attracted attention, with prokinetic agents and herbal medicines often being administered in Japan to accelerate gastric emptying in patients who have anorexia associated with dyspepsia. Recently, we found that addition of monosodium L-glutamate (MSG) to a high-calorie liquid diet rich in casein promoted gastric emptying in healthy men. Therefore, another potential method of improving delayed gastric emptying could be activation of chemosensors that stimulate the autonomic nervous system of the gastrointestinal tract, suggesting a role for MSG in the management of delayed gastric emptying in patients with FD. PMID:23886379

  16. Mechanics and polarity in cell motility

    NASA Astrophysics Data System (ADS)

    Ambrosi, D.; Zanzottera, A.

    2016-09-01

    The motility of a fish keratocyte on a flat substrate exhibits two distinct regimes: the non-migrating and the migrating one. In both configurations the shape is fixed in time and, when the cell is moving, the velocity is constant in magnitude and direction. Transition from a stable configuration to the other one can be produced by a mechanical or chemotactic perturbation. In order to point out the mechanical nature of such a bistable behaviour, we focus on the actin dynamics inside the cell using a minimal mathematical model. While the protein diffusion, recruitment and segregation govern the polarization process, we show that the free actin mass balance, driven by diffusion, and the polymerized actin retrograde flow, regulated by the active stress, are sufficient ingredients to account for the motile bistability. The length and velocity of the cell are predicted on the basis of the parameters of the substrate and of the cell itself. The key physical ingredient of the theory is the exchange among actin phases at the edges of the cell, that plays a central role both in kinematics and in dynamics.

  17. Small intestine motility development in newborn mammals.

    PubMed

    Woliński, Jarosław; Słupecka-Ziemilska, Monika; Boryczka, Maria; Grzesiak, Paulina; Kwiatkowski, Jakub; Kotarba, Grzegorz

    2016-01-01

    Since the beginning of the 20th century, researchers have been working to improve the understanding of gastrointestinal motility. The first major discovery was the observation of a migrating myoelectric complex that turned out to be a universal occurrence among vertebrates. Further inquires resulted in a detailed description of its development during different stages of ontogeny. Some time before that, a cornerstone had been laid for a breakthrough that would come years later. That cornerstone came in the form of interstitial cells of Cajal whose true role could not be discerned until the discovery of a CD117 receptor - their main marker. With the ability to precisely mark interstitial cells of Cajal, a wave of subsequent new experiments and observations connected them to the occurrence of slow waves and allowed an understanding of the mechanism responsible for their generation. Some of these findings suggested that Cajal cells might have a role in the development of several motility disorders thus opening an avenue of research that requires the usage of both traditional and advanced diagnostic methods. PMID:27416626

  18. The mechanics of motility in dissociated cytoplasm.

    PubMed Central

    Dembo, M

    1986-01-01

    We stimulate the dynamical behavior of dissociated cytoplasm using the Reactive Flow Model (Dembo, M., and F. Harlow, 1986, Biophys. J., 50:109-121). We find that for the most part the predicted dynamical behavior of the cytoplasm is governed by three nondimensional numbers. Several other nondimensional parameters, the initial conditions, and boundary conditions are found to have lesser effects. Of the three major nondimensional parameters, one (D#) controls the percentage of ectoplasm, the second (C#) controls the sharpness of the endoplasm-ectoplasm boundary, and the third (R#) controls the topological complexity of the endoplasm-ectoplasm distribution. If R# is very small, then the cytoplasm contracts into a single uniform mass, and there is no bulk streaming. If R# is very large, then the cytoplasmic mass breaks up into a number of clumps scattered throughout the available volume. Between these clumps the solution undergoes turbulent or chaotic patterns of streaming. Intermediate values of R# can be found such that the mass of cytoplasm remains connected and yet undergoes coherent modes of motility similar to flares (Taylor, D.L., J.S. Condeelis, P.L. Moore, and R.D. Allen, 1973, J. Cell Biol., 59:378-394) and rosettes (Kuroda, K., 1979, Cell Motility: Molecules and Organization, 347-362). Images FIGURE 1 FIGURE 1B FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 PMID:3801576

  19. Bacterial Keratitis

    MedlinePlus

    ... very quickly, and if left untreated, can cause blindness. The bacteria usually responsible for this type of ... to intense ultraviolet radiation exposure, e.g. snow blindness or welder's arc eye). Next Bacterial Keratitis Symptoms ...

  20. Using Liquid Crystals to Reveal How Mechanical Anisotropy Changes Interfacial Behaviors of Motile Bacteria

    PubMed Central

    Mushenheim, Peter C.; Trivedi, Rishi R.; Weibel, Douglas B.; Abbott, Nicholas L.

    2014-01-01

    Bacteria often inhabit and exhibit distinct dynamical behaviors at interfaces, but the physical mechanisms by which interfaces cue bacteria are still poorly understood. In this work, we use interfaces formed between coexisting isotropic and liquid crystal (LC) phases to provide insight into how mechanical anisotropy and defects in LC ordering influence fundamental bacterial behaviors. Specifically, we measure the anisotropic elasticity of the LC to change fundamental behaviors of motile, rod-shaped Proteus mirabilis cells (3 μm in length) adsorbed to the LC interface, including the orientation, speed, and direction of motion of the cells (the cells follow the director of the LC at the interface), transient multicellular self-association, and dynamical escape from the interface. In this latter context, we measure motile bacteria to escape from the interfaces preferentially into the isotropic phase, consistent with the predicted effects of an elastic penalty associated with strain of the LC about the bacteria when escape occurs into the nematic phase. We also observe boojums (surface topological defects) present at the interfaces of droplets of nematic LC (tactoids) to play a central role in mediating the escape of motile bacteria from the LC interface. Whereas the bacteria escape the interface of nematic droplets via a mechanism that involved nematic director-guided motion through one of the two boojums, for isotropic droplets in a continuous nematic phase, the elasticity of the LC generally prevented single bacteria from escaping. Instead, assemblies of bacteria piled up at boojums and escape occurred through a cooperative, multicellular phenomenon. Overall, our studies show that the dynamical behaviors of motile bacteria at anisotropic LC interfaces can be understood within a conceptual framework that reflects the interplay of LC elasticity, surface-induced order, and topological defects. PMID:24988359

  1. Effect of Motility on Surface Colonization and Reproductive Success of Pseudomonas fluorescens in Dual-Dilution Continuous Culture and Batch Culture Systems

    PubMed Central

    Korber, Darren R.; Lawrence, John R.; Caldwell, Douglas E.

    1994-01-01

    The colonization of glass surfaces by motile and nonmotile strains of Pseudomonas fluorescens was evaluated by using dual-dilution continuous culture (DDCC), competitive and noncompetitive attachment assays, and continuous-flow slide culture. Both strains possessed identical growth rates whether in the attached or planktonic state. Results of attachment assays using radiolabeled bacteria indicated that both strains obeyed first-order (monolayer) adsorption kinetics in pure culture. However, the motile strain attached about four times more rapidly and achieved higher final cell densities on surfaces than did the nonmotile strain (2.03 × 108 versus 5.57 × 107 cells vial-1) whether evaluated alone or in cocultures containing motile and nonmotile P. fluorescens. These kinetics were attributed to the increased transport of motile cells from the bulk aqueous phase to the hydrodynamic boundary layer where bacterial attachment, growth, and recolonization could occur. First-order attachment kinetics were also observed for both strains by using continuous-flow slide culture assays analyzed by image analysis. The DDCC system contained both aqueous and particulate phases which could be diluted independently. DDCC results indicated that when cocultures containing motile and nonmotile P. fluorescens colonized solid particles, the motile strain replaced the nonmotile strain in the system over time. Increasing the aqueous-phase rates of dilution decreased the time required for extinction of the nonmotile strain while concurrently decreasing the overall carrying capacity of the DDCC system for both strains. These results confirmed that bacterial motility conveyed a selective advantage during surface colonization even in aqueous-phase systems not dominated by laminar flow. PMID:16349247

  2. Bacterial aggregation and biofilm formation in a vortical flow

    PubMed Central

    Yazdi, Shahrzad; Ardekani, Arezoo M.

    2012-01-01

    Bacterial aggregation and patchiness play an important role in a variety of ecological processes such as competition, adaptation, epidemics, and succession. Here, we demonstrate that hydrodynamics of their environment can lead to their aggregation. This is specially important since microbial habitats are rarely at rest (e.g., ocean, blood stream, flow in porous media, and flow through membrane filtration processes). In order to study the dynamics of bacterial collection in a vortical flow, we utilize a microfluidic system to mimic some of the important microbial conditions at ecologically relevant spatiotemporal scales. We experimentally demonstrate the formation of “ring”-shaped bacterial collection patterns and subsequently the formation of biofilm streamers in a microfluidic system. Acoustic streaming of a microbubble is used to generate a vortical flow in a microchannel. Due to bacteria's finite-size, the microorganisms are directed to closed streamlines and trapped in the vortical flow. The collection of bacteria in the vortices occurs in a matter of seconds, and unexpectedly, triggers the formation of biofilm streamers within minutes. Swimming bacteria have a competitive advantage to respond to their environmental conditions. In order to investigate the role of bacterial motility on the rate of collection, two strains of Escherichia coli bacteria with different motilities are used. We show that the bacterial collection in a vortical flow is strongly pronounced for high motile bacteria. PMID:24339847

  3. 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

  4. 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. PMID:24391847

  5. Virulent Burkholderia species mimic host actin polymerases to drive actin-based motility

    PubMed Central

    Benanti, Erin L.; Nguyen, Catherine M.; Welch, Matthew D.

    2015-01-01

    Summary Burkholderia pseudomallei and B. mallei are bacterial pathogens that cause melioidosis and glanders, while their close relative B. thailandensis is nonpathogenic. All use the trimeric autotransporter BimA to facilitate actin-based motility, host cell fusion and dissemination. Here, we show that BimA orthologs mimic different host actin-polymerizing proteins. B. thailandensis BimA activates the host Arp2/3 complex. In contrast, B. pseudomallei and B. mallei BimA mimic host Ena/VASP actin polymerases in their ability to nucleate, elongate and bundle filaments by associating with barbed ends, as well as in their use of WH2 motifs and oligomerization for activity. Mechanistic differences among BimA orthologs resulted in distinct actin filament organization and motility parameters, which affected the efficiency of cell fusion during infection. Our results identify bacterial Ena/VASP mimics and reveal that pathogens imitate the full spectrum of host actin-polymerizing pathways, suggesting that mimicry of different polymerization mechanisms influences key parameters of infection. PMID:25860613

  6. 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

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

    PubMed Central

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

    2015-01-01

    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

  8. 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

  9. Motility and Chemotaxis Mediate the Preferential Colonization of Gastric Injury Sites by Helicobacter pylori

    PubMed Central

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

    2014-01-01

    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 (106) failed to colonize ulcerated or healthy stomach tissue. ΔcheY (106) 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 biases

  10. 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.

  11. 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. PMID:25673121

  12. 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.

  13. A novel flagellar sheath protein, FcpA, determines filament coiling, translational motility and virulence for the Leptospira spirochete.

    PubMed

    Wunder, Elsio A; Figueira, Cláudio P; Benaroudj, Nadia; Hu, Bo; Tong, Brian A; Trajtenberg, Felipe; Liu, Jun; Reis, Mitermayer G; Charon, Nyles W; Buschiazzo, Alejandro; Picardeau, Mathieu; Ko, Albert I

    2016-08-01

    Leptospira are unique among bacteria based on their helical cell morphology with hook-shaped ends and the presence of periplasmic flagella (PF) with pronounced spontaneous supercoiling. The factors that provoke such supercoiling, as well as the role that PF coiling plays in generating the characteristic hook-end cell morphology and motility, have not been elucidated. We have now identified an abundant protein from the pathogen L. interrogans, exposed on the PF surface, and named it Flagellar-coiling protein A (FcpA). The gene encoding FcpA is highly conserved among Leptospira and was not found in other bacteria. fcpA(-) mutants, obtained from clinical isolates or by allelic exchange, had relatively straight, smaller-diameter PF, and were not able to produce translational motility. These mutants lost their ability to cause disease in the standard hamster model of leptospirosis. Complementation of fcpA restored the wild-type morphology, motility and virulence phenotypes. In summary, we identified a novel Leptospira 36-kDa protein, the main component of the spirochete's PF sheath, and a key determinant of the flagella's coiled structure. FcpA is essential for bacterial translational motility and to enable the spirochete to penetrate the host, traverse tissue barriers, disseminate to cause systemic infection and reach target organs. PMID:27113476

  14. 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. PMID:26406373

  15. 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.

  16. 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.

  17. Metabolism and motility in prebiotic structures

    PubMed Central

    Hanczyc, Martin M.

    2011-01-01

    Easily accessible, primitive chemical structures produced by self-assembly of hydrophobic substances into oil droplets may result in self-moving agents able to sense their environment and move to avoid equilibrium. These structures would constitute very primitive examples of life on the Earth, even more primitive than simple bilayer vesicle structures. A few examples of simple chemical systems are presented that self-organize to produce oil droplets capable of movement, environment remodelling and primitive chemotaxis. These chemical agents are powered by an internal chemical reaction based on the hydrolysis of an oleic anhydride precursor or on the hydrolysis of hydrogen cyanide (HCN) polymer, a plausible prebiotic chemistry. Results are presented on both the behaviour of such droplets and the surface-active properties of HCN polymer products. Such motile agents would be capable of finding resources while escaping equilibrium and sustaining themselves through an internal metabolism, thus providing a working chemical model for a possible origin of life. PMID:21930579

  18. 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

  19. Motile Cilia of Human Airway Epithelia Are Chemosensory

    PubMed Central

    Shah, Alok S; Ben-Shahar, Yehuda; Moninger, Thomas O; Kline, Joel N; Welsh, Michael J

    2010-01-01

    Cilia are microscopic projections that extend from eukaryotic cells. There are two general types of cilia; primary cilia serve as sensory organelles, whereas motile cilia exert mechanical force. The motile cilia emerging from human airway epithelial cells propel harmful inhaled material out of the lung. We found that these cells express sensory bitter taste receptors, which localized on motile cilia. Bitter compounds increased the intracellular Ca2+ concentration and stimulated ciliary beat frequency. Thus, airway epithelia contain a cell-autonomous system in which motile cilia both sense noxious substances entering airways and initiate a defensive mechanical mechanism to eliminate the offending compound. Hence, like primary cilia, classical motile cilia also contain sensors to detect the external environment. PMID:19628819

  20. 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

  1. Acanthamoeba feature a unique backpacking strategy to trap and feed on Listeria monocytogenes and other motile bacteria.

    PubMed

    Doyscher, Dominik; Fieseler, Lars; Dons, Lone; Loessner, Martin J; Schuppler, Markus

    2013-02-01

    Despite its prominent role as an intracellular human pathogen, Listeria monocytogenes normally features a saprophytic lifestyle, and shares many environmental habitats with predatory protozoa. Earlier studies claimed that Acanthamoeba may act as environmental reservoirs for L. monocytogenes, whereas others failed to confirm this hypothesis. Our findings support the latter and provide clear evidence that L. monocytogenes is unable to persist in Acanthamoeba castellanii and A. polyphaga. Instead, external Listeria cells are rapidly immobilized on the surface of Acanthamoeba trophozoites, forming large aggregates of densely packed bacteria that we termed backpacks. While the assembly of backpacks is dependent on bacterial motility, flagellation alone is not sufficient. Electron micrographs showed that the aggregates are held together by filaments of likely amoebal origin. Time-lapse microscopy revealed that shortly after the bacteria are collected, the amoeba can change direction of movement, phagocytose the backpack and continue to repeat the process. The phenomenon was also observed with avirulent L. monocytogenes mutants, non-pathogenic Listeria, and other motile bacteria, indicating that formation of backpacks is not specific for L. monocytogenes, and independent of bacterial pathogenicity or virulence. Hence, backpacking appears to represent a unique and highly effective strategy of Acanthamoeba to trap and feed on motile bacteria. PMID:22925311

  2. 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

  3. Bacterial Immunity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A variety of bacterial agents reside in and around the environment that can cause illness and death in a poultry flock. Many cause disseminated disease while others exert more local effects such as the respiratory or gastrointestinal tract. The host, for our current purposes the laying hen, has de...

  4. 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

  5. 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. PMID:24528485

  6. Small intestinal bacterial overgrowth syndrome

    PubMed Central

    Bures, Jan; Cyrany, Jiri; Kohoutova, Darina; Förstl, Miroslav; Rejchrt, Stanislav; Kvetina, Jaroslav; Vorisek, Viktor; Kopacova, Marcela

    2010-01-01

    Human intestinal microbiota create a complex polymicrobial ecology. This is characterised by its high population density, wide diversity and complexity of interaction. Any dysbalance of this complex intestinal microbiome, both qualitative and quantitative, might have serious health consequence for a macro-organism, including small intestinal bacterial overgrowth syndrome (SIBO). SIBO is defined as an increase in the number and/or alteration in the type of bacteria in the upper gastrointestinal tract. There are several endogenous defence mechanisms for preventing bacterial overgrowth: gastric acid secretion, intestinal motility, intact ileo-caecal valve, immunoglobulins within intestinal secretion and bacteriostatic properties of pancreatic and biliary secretion. Aetiology of SIBO is usually complex, associated with disorders of protective antibacterial mechanisms (e.g. achlorhydria, pancreatic exocrine insufficiency, immunodeficiency syndromes), anatomical abnormalities (e.g. small intestinal obstruction, diverticula, fistulae, surgical blind loop, previous ileo-caecal resections) and/or motility disorders (e.g. scleroderma, autonomic neuropathy in diabetes mellitus, post-radiation enteropathy, small intestinal pseudo-obstruction). In some patients more than one factor may be involved. Symptoms related to SIBO are bloating, diarrhoea, malabsorption, weight loss and malnutrition. The gold standard for diagnosing SIBO is still microbial investigation of jejunal aspirates. Non-invasive hydrogen and methane breath tests are most commonly used for the diagnosis of SIBO using glucose or lactulose. Therapy for SIBO must be complex, addressing all causes, symptoms and complications, and fully individualised. It should include treatment of the underlying disease, nutritional support and cyclical gastro-intestinal selective antibiotics. Prognosis is usually serious, determined mostly by the underlying disease that led to SIBO. PMID:20572300

  7. 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

  8. 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. PMID:26244150

  9. 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. PMID:27157805

  10. Pattern-formation mechanisms in motility mutants of Myxococcus xanthus

    PubMed Central

    Starruß, Jörn; Peruani, Fernando; Jakovljevic, Vladimir; Søgaard-Andersen, Lotte; Deutsch, Andreas; Bär, Markus

    2012-01-01

    Formation of spatial patterns of cells is a recurring theme in biology and often depends on regulated cell motility. Motility of the rod-shaped cells of the bacterium Myxococcus xanthus depends on two motility machineries, type IV pili (giving rise to S-motility) and the gliding motility apparatus (giving rise to A-motility). Cell motility is regulated by occasional reversals. Moving M. xanthus cells can organize into spreading colonies or spore-filled fruiting bodies, depending on their nutritional status. To ultimately understand these two pattern-formation processes and the contributions by the two motility machineries, as well as the cell reversal machinery, we analyse spatial self-organization in three M. xanthus strains: (i) a mutant that moves unidirectionally without reversing by the A-motility system only, (ii) a unidirectional mutant that is also equipped with the S-motility system, and (iii) the wild-type that, in addition to the two motility systems, occasionally reverses its direction of movement. The mutant moving by means of the A-engine illustrates that collective motion in the form of large moving clusters can arise in gliding bacteria owing to steric interactions of the rod-shaped cells, without the need of invoking any biochemical signal regulation. The two-engine strain mutant reveals that the same phenomenon emerges when both motility systems are present, and as long as cells exhibit unidirectional motion only. From the study of these two strains, we conclude that unidirectional cell motion induces the formation of large moving clusters at low and intermediate densities, while it results in vortex formation at very high densities. These findings are consistent with what is known from self-propelled rod models, which strongly suggests that the combined effect of self-propulsion and volume exclusion interactions is the pattern-formation mechanism leading to the observed phenomena. On the other hand, we learn that when cells occasionally reverse