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Sample records for peritrichously flagellated chemotactic

  1. Adaptation and optimal chemotactic strategy for {ital E. coli}

    SciTech Connect

    Strong, S.P.; Bialek, William; Koberle, R. Freedman, B.

    1998-04-01

    Extending the classic works of Berg and Purcell on the biophysics of bacterial chemotaxis, we find the optimal chemotactic strategy for the peritrichous bacterium {ital E. coli} in the high and low signal to noise ratio limits. The optimal strategy depends on properties of the environment and properties of the individual bacterium, and is therefore highly adaptive. We review experiments relevant to testing both the form of the proposed strategy and its adaptability, and propose extensions of them which could test the limits of the adaptability in this simplest sensory processing system. {copyright} {ital 1998} {ital The American Physical Society}

  2. Epistylis smalli (Ciliophora: Peritrichia) a new peritrich from Guaiba Lake, Southern Brazil.

    PubMed

    Utz, Laura R P; Dos Santos, Mariana Silva; De Araujo, Gabriella Oliveira

    2015-01-01

    Epistylis smalli n. sp., a freshwater colonial peritrich, was collected in Guaíba Lake, Southern Brazil. Its morphology was investigated using in vivo observations and protargol stained specimens. E. smalli possess an elongate zooid that measures in vivo, on average, 173 μm in length and 50 μm in width. A C-shaped macronucleus that surrounds the infundibulum and a single contractile vacuole could be easily observed in the living cell. The oral infraciliature observed in silver-stained specimens was typical of peritrich ciliates, with three infundibular polykinetids bearing three rows of kinetosomes. A detailed description of the live and stained zooids is given. PMID:26624684

  3. Revealing the Diversity and Quantity of Peritrich Ciliates in Environmental Samples Using Specific Primer-based PCR and Quantitative PCR

    PubMed Central

    Liu, Xihan; Gong, Jun

    2012-01-01

    Peritrichs are a diverse, ecologically important ciliate group usually with a complex life cycle. To date, the community of the peritrichs has been investigated by using morphology-based methods such as living observation and silver staining. Here we show a molecular approach for characterizing the diversity and quantity of free-living peritrichs in environmental samples. We newly designed four peritrich-specific primers targeting 18S rRNA genes that allow clone library construction, screening and analysis. A quantitative real-time PCR (qPCR) assay was developed to quantify peritrichs in environmental samples by using rDNA copy number as an indicator. DNA extracted from four water samples of contrasting environmental gradients was analysed. The results showed that the peritrich community was differentiated among these samples, and that the diversity decreased with the increase of water salinity. The qPCR results are consistent with the library sequence analysis in terms of quantity variations from sample to sample. The development of peritrich-specific primers, for the first time, for conventional PCR and qPCR assays, provides useful molecular tools for revealing the diversity and quantity of peritrich ciliates in environmental samples. Also, our study illustrates the potential of these molecular tools to ecological studies of other ciliate groups in diverse environments. PMID:23100023

  4. Feeding and swimming of flagellates

    NASA Astrophysics Data System (ADS)

    Doelger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas; Bohr, Tomas; Andersen, Anders

    2015-11-01

    Hydrodynamics plays a dominant role for small planktonic flagellates and shapes their survival strategies. The high diversity of beat patterns and arrangements of appendages indicates different strategies balancing the trade-offs between the general goals, i.e., energy-efficient swimming, feeding, and predator avoidance. One type of flagellated algae that we observe, are haptophytes, which possess two flagella for flow creation and one so-called haptonema, a long, rigid structure fixed on the cell body, which is used for prey capture. We present videos and flow fields obtained using velocimetry methods around freely swimming haptophytes and other flagellates, which we compare to analytical results obtained from point force models. The observed and modelled flows are used to analyse how different morphologies and beat patterns relate to different feeding or swimming strategies, such as the capture mechanism in haptophytes. The Centre for Ocean Life is a VKR center of excellence supported by the Villum foundation.

  5. Gravitaxis and graviperception in flagellates

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.; Lebert, M.; Richter, P.; Ntefidou, M.

    2003-05-01

    There is strong evidence that gravitactic orientation in flagellates and ciliates is mediated by an active physiological gravireceptor rather than by passive alignment of the cells in the water column. In flagellates the threshold for graviorientation was found to be at 0.12 × g on a slow rotating centrifuge during the IML-2 mission on the Shuttle Columbia and a subsequent parabolic rocket flight (TEXUS). During the IML-2 mission no adaptation to microgravity was observed over the duration of the space flight, while gravitaxis was lost in a terrestrial closed environmental system over the period of almost two years. Sedimenting statoliths are not likely to be involved in graviperception because of the small size of the cells and their rotation around the longitudinal axis during forward locomotion. Instead the whole cytoplasmic content of the cell, being heavier than the surrounding aqueous medium (1.05 g/ml), exerts a pressure on the lower membrane. This force activates stretch-sensitive calcium specific ion channels which can be inhibited by the addition of gadolinium which therefore abolishes gravitaxis. The channels seem to mainly allow calcium ions to pass since gravitaxis is blocked by the addition of the calcium ionophore A23187 and by vanadate which blocks the Ca-ATPase in the cytoplasmic membrane. Recently, a gene for a mechanosensitive channel, originally sequenced for Saccharomyces, was identified in Euglena by PCR. The increase in intracellular free calcium during reorientation can be visualized by the fluorophore Calcium Crimson using laser excitation and image intensification. This result was confirmed during recent parabolic flights. The gated calcium changes the membrane potential across the membrane which may be the trigger for the reorientation of the flagellum. cAMP plays a role as a secondary messenger. Photosynthetic flagellates are suitable candidates for life support systems since they absorb CO 2 and produce oxygen. Preliminary experiments

  6. Graviperception and gravitaxis in flagellates

    NASA Astrophysics Data System (ADS)

    Häder, D.; Ntefidou, M.

    Many photosynthetic and heterotrophic flagellates perceive and respond to the gravitational vector of the Earth. Some previous hypotheses have suggested that the orientation is brought about by a passive physical mechanism such as buoyancy or hydrodynamic alignment. However, recent results have confirmed that e.g. the photosynthetic Euglena utilizes an active physiological sensor and an internal sensory transduction chain. This unicellular organism senses gravity by the sedimentation of its cellular content, which is heavier than the surrounding medium, onto the lower membrane. This force is believed to activate mechano-sensitive ion channels located at the front end under the trailing flagellum. The channels allow a gated influx of calcium which alters the internal electrical potential and may activate calmodulin. Further elements in the transduction chain are cyclic AMP and related enzymes. Recent flight experiments during parabolic aircraft maneuvers and on sounding rockets have confirmed previous terrestrial results and have provided detailed insight into the biochemical sensory transduction chain.

  7. Chemotactic behavior of Campylobacter jejuni.

    PubMed Central

    Hugdahl, M B; Beery, J T; Doyle, M P

    1988-01-01

    The chemotactic behavior of Campylobacter jejuni was determined in the presence of different amino acids, carbohydrates, organic acids, and preparations and constituents of mucin and bile. L-Fucose was the only carbohydrate and L-aspartate, L-cysteine, L-glutamate, and L-serine were the only amino acids producing a chemotactic (positive) response. Several salts of organic acids, including pyruvate, succinate, fumarate, citrate, malate, and alpha-ketoglutarate, were also chemoattractants, as were bile (beef, chicken, and oxgall) and mucin (bovine gallbladder and hog gastric). Most constituents of bile tested individually were chemorepellents, but the mucin component was chemoattractant. The chemotactic behavior of C. jejuni toward L-fucose, a constituent of both bile and mucin, may be an important factor in the affinity of the organism for the gallbladder and intestinal tract. Images PMID:3372020

  8. Graviperception and gravitaxis in flagellates

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.; Richter, P.; Ntefidou, M.; Lebert, M.

    Unicellular flagellates perceive and react to the gravitational vector of the Earth. Previous hypotheses have suggested that the orientation is brought about by a passive physical mechanism such as buoyancy or hydrodynamic alignment. Recent results of experiments on parabolic rocket flights have revealed that in the photosynthetic Euglena only 10 % of the orientation can be explained by passive orientation while the remainder relies on an active physiological sensor and an internal sensory transduction chain. The cellular contents is heavier than the surrounding medium and consequently presses onto the lower membrane where it activates mechano-sensitive ion channels located at the front end under the trailing flagellum. These channels allow a gated influx of calcium (visualized by confocal microscopy) which depolarizes the internal electrical potential and eventually causes a course correction by the flagellar beating. Further elements in the transduction chain are cyclic AMP and related enzymes. Recent experiments during parabolic aircraft flights and on sounding rockets have confirmed this hypothesis and provided detailed insight into the biochemical sensory transduction chain. Currently the molecular mechanisms of graviperception are being studied.

  9. A Non-Poissonian Flagellar Motor Switch Increases Bacterial Chemotactic Potential.

    PubMed

    Yang, Yang; He, Jing; Altindal, Tuba; Xie, Li; Wu, Xiao-Lun

    2015-09-01

    We investigate bacterial chemotactic strategies using run-tumble and run-reverse-flick motility patterns. The former is typically observed in enteric bacteria such as Escherichia coli and Salmonella and the latter was recently observed in the marine bacteria Vibrio alginolyticus and is possibly exhibited by other polar flagellated species. It is shown that although the three-step motility pattern helps the bacterium to localize near hot spots, an exploitative behavior, its exploratory potential in short times can be significantly enhanced by employing a non-Poissonian regulation scheme for its flagellar motor switches. PMID:26331263

  10. Cinemicrographic analysis of the movement of flagellated bacteria. II. The ratio of the propulsive velocity to the frequency of the wave propagation along flagellar tail.

    PubMed

    Shimada, K; Ikkai, T; Yoshida, T; Asakura, S

    1976-03-01

    We took cinemicrographs of the movement of the flagellar tail of the peritrichously flagellated bacterium, Salmonella, swimming in a medium containing methylcellulose under a dark-ground microscope. By analysing the film, the velocity of translation u, the frequency of the propagation of helical waves along the tail fF and the frequency of the induced rotation of bacterial body fB of individual organism were measured and the experimental values of the ratios u/fF, u/fB and fF/fB were obtained. On the other hand, the theoretical values of these ratios were calculated by inserting the geometrical parameters describing the shapes and the sizes of the body and the tail of individual organism into the equations previously derived for the hydrodynamic model of the propulsion of flagellated bacteria (Holwill and Burge, 1963; Chwang and Wu, 1971). For four bacterial specimens presently analysed, the experimental values of u/fF ranged from 0.5 to 0.9, whereas the theoretical values were about 0.3. As reported by the preceding paper, such a tendency for the experimental values to exceed the theoretical ones by two or three times was also seen in u/fB and, consequently, the experimental and the theoretical values of fF/fB showed good agreement. From the results of these quantitative analyses of the movements of flagellated bacteria, it was concluded that the validity of the hydrodynamic model was further supported experimentally. PMID:932565

  11. Chemotactic signal integration in bacteria.

    PubMed Central

    Khan, S; Spudich, J L; McCray, J A; Trentham, D R

    1995-01-01

    Chemotactic signaling in Escherichia coli involves transmission of both negative and positive signals. In order to examine mechanisms of signal processing, behavioral responses to dual inputs have been measured by using photoactivable "caged" compounds, computer video analysis, and chemoreceptor deletion mutants. Signaling from Tar and Tsr, two receptors that sense amino acids and pH, was studied. In a Tar deletion mutant the photoactivated release of protons, a Tsr repellent, and of serine, a Tsr attractant, in separate experiments at pH 7.0 resulted in tumbling (negative) or smooth-swimming (positive) responses in ca. 50 and 140 ms, respectively. Simultaneous photorelease of protons and serine resulted in a single tumbling or smooth-swimming response, depending on the relative amounts of the two effectors. In contrast, in wild-type E. coli, proton release at pH 7.0 resulted in a biphasic response that was attributed to Tsr-mediated tumbling followed by Tar-mediated smooth-swimming. In wild-type E. coli at more alkaline pH values the Tar-mediated signal was stronger than the Tsr signal, resulting in a strong smooth-swimming response preceded by a diminished tumbling response. These observations imply that (i) a single receptor time-averages the binding of different chemotactic ligands generating a single response; (ii) ligand binding to different receptors can result in a nonintegrated response with the tumbling response preceding the smooth-swimming response; (iii) however, chemotactic signals of different intensities derived from different receptors can also result in an apparently integrated response; and (iv) the different chemotactic responses to protons at neutral and alkaline pH may contribute to E. coli migration toward neutrality. Images Fig. 6 PMID:7568212

  12. Glucose induces delocalization of a flagellar biosynthesis protein from the flagellated pole.

    PubMed

    Park, Soyoung; Park, Young-Ha; Lee, Chang-Ro; Kim, Yeon-Ran; Seok, Yeong-Jae

    2016-09-01

    To survive in a continuously changing environment, bacteria sense concentration gradients of attractants or repellents, and purposefully migrate until a more favourable habitat is encountered. While glucose is known as the most effective attractant, the flagellar biosynthesis and hence chemotactic motility has been known to be repressed by glucose in some bacteria. To date, the only known regulatory mechanism of the repression of flagellar synthesis by glucose is via downregulation of the cAMP level, as shown in a few members of the family Enterobacteriaceae. Here we show that, in Vibrio vulnificus, the glucose-mediated inhibition of flagellar motility operates by a completely different mechanism. In the presence of glucose, EIIA(Glc) is dephosphorylated and inhibits the polar localization of FapA (flagellar assembly protein A) by sequestering it from the flagellated pole. A loss or delocalization of FapA results in a complete failure of the flagellar biosynthesis and motility. However, when glucose is depleted, EIIA(Glc) is phosphorylated and releases FapA such that free FapA can be localized back to the pole and trigger flagellation. Together, these data provide new insight into a bacterial strategy to reach and stay in the glucose-rich area. PMID:27218601

  13. Chemotactic predator-prey dynamics.

    PubMed

    Sengupta, Ankush; Kruppa, Tobias; Löwen, Hartmut

    2011-03-01

    A discrete chemotactic predator-prey model is proposed in which the prey secrets a diffusing chemical which is sensed by the predator and vice versa. Two dynamical states corresponding to catching and escaping are identified and it is shown that steady hunting is unstable. For the escape process, the predator-prey distance is diffusive for short times but exhibits a transient subdiffusive behavior which scales as a power law t¹/³ with time t and ultimately crosses over to diffusion again. This allows us to classify the motility and dynamics of various predatory microbes and phagocytes. In particular, there is a distinct region in the parameter space where they prove to be infallible predators. PMID:21517532

  14. Relationship between the flagellates and the ciliates.

    PubMed Central

    Lee, R E; Kugrens, P

    1992-01-01

    The flagellates and the ciliates have long been considered to be closely related because of their unicellular nature and the similarity in the structures of the axoneme of the flagella and cilia in both groups. Most protozoologists believe that the ciliates arose from a flagellate. The flagellates that are most similar in structure to the ciliates are the dinoflagellates and two genera of uncertain taxonomic position, Colponema and Katablepharis. Structurally, dinoflagellates have a number of similarities with ciliates. These include the similarity of the cortical alveoli in the ciliates to the thecal vesicles in the dinoflagellates, the possession of tubular cristae, the similarity of the parasomal sac of the ciliates to the pusule of the dinoflagellates, the possession of similar trichocysts and mucocysts, and some similarity in the feeding apparatus. Colponema spp. are probably related to the dinoflagellates and have many of the same similarities with the ciliates. Katablepharis spp. are very similar in structure to the swarmer (embryo) of the suctorian ciliates. Indeed, reduction in the number of cilia to two in the suctorian swarmer and elimination of the macronucleus would result in a cell that is very similar to the Katablepharis cell. The feeding apparatus of Katablepharis spp. and the rest of the ciliates consists of two concentric microtubular arrays associated with vesicles. Information available from nucleotide sequencing of rRNA places the dinoflagellates in an ancestral position to the ciliates. The rRNA of Colponema and Katablepharis spp. has not yet been investigated. The use of stop codons in mRNA is discussed in relation to phylogeny. Images PMID:1480107

  15. Small but Manifold - Hidden Diversity in "Spumella-like Flagellates".

    PubMed

    Grossmann, Lars; Bock, Christina; Schweikert, Michael; Boenigk, Jens

    2016-07-01

    Colourless, nonscaled chrysophytes comprise morphologically similar or even indistinguishable flagellates which are important bacterivors in water and soil crucial for ecosystem functioning. However, phylogenetic analyses indicate a multiple origin of such colourless, nonscaled flagellate lineages. These flagellates are often referred to as "Spumella-like flagellates" in ecological and biogeographic studies. Although this denomination reflects an assumed polyphyly, it obscures the phylogenetic and taxonomic diversity of this important flagellate group and, thus, hinders progress in lineage- and taxon-specific ecological surveys. The smallest representatives of colourless chrysophytes have been addressed in very few taxonomic studies although they are among the dominant flagellates in field communities. To overcome the blurred picture and set the field for further investigation in biogeography and ecology of the organisms in question, we studied a set of strains of specifically small, colourless, nonscaled chrysomonad flagellates by means of electron microscopy and molecular analyses. They were isolated by a filtration-acclimatisation approach focusing on flagellates of around 5 μm. We present the phylogenetic position of eight different lineages on both the ordinal and the generic level. Accordingly, we describe the new genera Apoikiospumella, Chromulinospumella, Segregatospumella, Cornospumella and Acrispumella Boenigk et Grossmann n. g. and different species within them. PMID:26662881

  16. Morphological and Molecular Characterization of Some Peritrichs (Ciliophora: Peritrichida) from Tank Bromeliads, Including Two New Genera: Orborhabdostyla and Vorticellides.

    PubMed

    Foissner, Wilhelm; Blake, Natalie; Wolf, Klaus; Breiner, Hans-Werner; Stoeck, Thorsten

    2010-01-22

    Using standard methods, we studied the morphology and 18S rDNA sequence of some peritrich ciliates from tank bromeliads of Costa Rica, Jamaica, and Ecuador. The new genus Orborhabdostyla differs from Rhabdostyla by the discoidal macronucleus. Two species from the literature and a new species from Ecuadoran tank bromeliads are combined with the new genus: O. previpes (Claparède and Lachmann, 1857) nov. comb., O. kahli (Nenninger, 1948) nov. comb., and O. bromelicola nov. spec. Orborhabdostyla bromelicola is a slender species with stalk-like narrowed posterior half and operculariid/epistylidid oral apparatus. An epistylidid relationship is also suggested by the gene sequence. Vorticella gracilis, described by Dujardin (1841) from French freshwater, belongs to the V. convallaria complex but differs by the yellowish colour and the number of silverlines. The classification as a distinct species is supported by the 18S rDNA, which differs nearly 10% from that of V. convallaria s. str. Based on the new data, especially the very stable yellowish colour, we neotypify V. gracilis with the Austrian population studied by Foissner (1979). Vorticella gracilis forms a strongly supported phyloclade together with V. campanula, V. fusca and V. convallaria, while Vorticellides astyliformis and Vorticella microstoma branch in a separate, fully-supported clade that includes Astylozoon and Opisthonecta. The new genus Vorticellides comprises five small (usually < 60 μm), barrel-shaped species with two epistomial membranes: V. aquadulcis (Stokes, 1887) nov. comb., V. astyliformis (Foissner, 1981) nov. comb., V. platysoma (Stokes, 1887) nov. comb., V. infusionum (Dujardin, 1841) nov. comb., and V. (Spinivorticellides) echini (King, 1931) nov. comb. Two of these species are redescribed in the present study: V. astyliformis and V. aquadulcis, which is neotypified with a Costa Rican population. Pseudovorticella bromelicola nov. spec. differs from the congeners by the location of the two

  17. Morphological and Molecular Characterization of Some Peritrichs (Ciliophora: Peritrichida) from Tank Bromeliads, Including Two New Genera: Orborhabdostyla and Vorticellides

    PubMed Central

    FOISSNER, Wilhelm; BLAKE, Natalie; WOLF, Klaus; BREINER, Hans-Werner; STOECK, Thorsten

    2010-01-01

    Summary Using standard methods, we studied the morphology and 18S rDNA sequence of some peritrich ciliates from tank bromeliads of Costa Rica, Jamaica, and Ecuador. The new genus Orborhabdostyla differs from Rhabdostyla by the discoidal macronucleus. Two species from the literature and a new species from Ecuadoran tank bromeliads are combined with the new genus: O. previpes (Claparède and Lachmann, 1857) nov. comb., O. kahli (Nenninger, 1948) nov. comb., and O. bromelicola nov. spec. Orborhabdostyla bromelicola is a slender species with stalk-like narrowed posterior half and operculariid/epistylidid oral apparatus. An epistylidid relationship is also suggested by the gene sequence. Vorticella gracilis, described by Dujardin (1841) from French freshwater, belongs to the V. convallaria complex but differs by the yellowish colour and the number of silverlines. The classification as a distinct species is supported by the 18S rDNA, which differs nearly 10% from that of V. convallaria s. str. Based on the new data, especially the very stable yellowish colour, we neotypify V. gracilis with the Austrian population studied by Foissner (1979). Vorticella gracilis forms a strongly supported phyloclade together with V. campanula, V. fusca and V. convallaria, while Vorticellides astyliformis and Vorticella microstoma branch in a separate, fully-supported clade that includes Astylozoon and Opisthonecta. The new genus Vorticellides comprises five small (usually < 60 μm), barrel-shaped species with two epistomial membranes: V. aquadulcis (Stokes, 1887) nov. comb., V. astyliformis (Foissner, 1981) nov. comb., V. platysoma (Stokes, 1887) nov. comb., V. infusionum (Dujardin, 1841) nov. comb., and V. (Spinivorticellides) echini (King, 1931) nov. comb. Two of these species are redescribed in the present study: V. astyliformis and V. aquadulcis, which is neotypified with a Costa Rican population. Pseudovorticella bromelicola nov. spec. differs from the congeners by the location of the

  18. Hydrodynamic theory of swimming of flagellated microorganisms.

    PubMed

    de la Torre, J G; Bloomfield, V A

    1977-10-01

    A theory of the type commonly used in polymer hydrodynamics is developed to calculate swimming properties of flagellated microorganisms. The overall shape of the particle is modeled as an array of spherical beads which act, at the same time, as frictional elements. The fluid velocity field is obtained as a function of the forces acting at each bead through Oseen-type, hydrodynamic interaction tensors. From the force and torque equilibrium conditions, such quantities as swimming velocity, angular velocity, and efficiency can be calculated. Application is made to a spherical body propelled by a helical flagellum. A recent theory by Lighthill, and earlier formulations based on tangential and normal frictional coefficients of a curved cylinder, CT and CN, are analyzed along with our theory. Although all the theories predict similar qualitative characteristics, such as optimal efficiency and the effect of fluid viscosity, they lead to rather different numerical values. In agreement with Lighthill, we found the formalisms based on CN and CT coefficients to be somewhat inaccurate, and head-flagellum interactions are shown to play an important role. PMID:901902

  19. Euglenoid flagellates: a multifaceted biotechnology platform.

    PubMed

    Krajčovič, Juraj; Matej Vesteg; Schwartzbach, Steven D

    2015-05-20

    Euglenoid flagellates are mainly fresh water protists growing in highly diverse environments making them well-suited for a multiplicity of biotechnology applications. Phototrophic euglenids possesses complex chloroplasts of green algal origin bounded by three membranes. Euglena nuclear and plastid genome organization, gene structure and gene expression are distinctly different from other organisms. Our observations on the model organism Euglena gracilis indicate that transcription of both the plastid and nuclear genome is insensitive to environmental changes and that gene expression is regulated mainly at the post-transcriptional level. Euglena plastids have been proposed as a site for the production of proteins and value added metabolites of biotechnological interest. Euglena has been shown to be a suitable protist species to be used for production of several compounds that are used in the production of cosmeceuticals and nutraceuticals, such as α-tocopherol, wax esters, polyunsaturated fatty acids, biotin and tyrosine. The storage polysaccharide, paramylon, has immunostimulatory properties and has shown a promise for biomaterials production. Euglena biomass can be used as a nutritional supplement in aquaculture and in animal feed. Diverse applications of Euglena in environmental biotechnology include ecotoxicological risk assessment, heavy metal bioremediation, bioremediation of industrial wastewater and contaminated water. PMID:25527385

  20. Nicotine is Chemotactic for Neutrophils and Enhances Neutrophil Responsiveness to Chemotactic Peptides

    NASA Astrophysics Data System (ADS)

    Totti, Noel; McCusker, Kevin T.; Campbell, Edward J.; Griffin, Gail L.; Senior, Robert M.

    1984-01-01

    Neutrophils contribute to chronic bronchitis and pulmonary emphysema associated with cigarette smoking. Nicotine was found to be chemotactic for human neutrophils but not monocytes, with a peak activity at ~ 31 micromolar. In lower concentrations (comparable to those in smokers' plasma), nicotine enhanced the response of neutrophils to two chemotactic peptides. In contrast to most other chemoattractants for neutrophils, however, nicotine did not affect degranulation or superoxide production. Nicotine thus may promote inflammation and consequent lung injury in smokers.

  1. Gravitational sensory transduction chain in flagellates

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.; Richter, P.; Ntefidou, M.; Lebert, M.

    Earlier hypotheses have assumed that gravitactic orientation in flagellates, such as the photosynthetic unicell Euglena gracilis, is brought about by passive alignment of the cells in the water column by being tail heavy. A recent experiment on a sounding rocket (TEXUS 40) comparing immobilized cells with mobile cells demonstrated that the passive buoy effect can account for approximately 20% of the orientation of the cells in a gravity field. The cells show either positive or negative gravitaxis depending on other external or internal factors. Shortly after inoculation, the tendency of young cells to swim downward in the water column can be readily reverted by adding micromolar concentrations of some heavy metal ions including copper, cadmium or lead. The negative gravitaxis of older cells is converted into a positive one by stress factors such as increasing salinity or exposure to excessive visible or UV radiation. The mechanism for this switch seems to involve reactive oxygen species since the gravitactic sign change was suppressed when oxygen was removed by flushing the cell suspension with nitrogen. Also, the addition of radical scavengers (Trolox, ascorbic acid or potassium cyanide) abolished or reduced the gravitactic sign change. Addition of hydrogen peroxide induced a gravitactic sign change in the absence of external stress factors. The primary reception for the gravity vector seems to involve mechanosensitive ion channels which specifically gate calcium ions inward. We have identified several gene sequences for putative mechanosensory channels in Euglena and have applied RNAi to identify which of these channels are involved in graviperception. The influx of Ca 2+ activates calmodulin (CaM) which has been shown to be involved in the sensory transduction chain of graviorientation. It is known that an adenylyl cyclase is bound to the flagellar membrane in Euglena which is activated by CaM. This enzyme produces cAMP which has also been shown to be the key

  2. Spatiotemporal chemotactic model for ant foraging

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Subramanian; Laurent, Thomas; Kumar, Manish; Bertozzi, Andrea L.

    2014-12-01

    In this paper, we present a generic theoretical chemotactic model that accounts for certain emergent behaviors observed in ant foraging. The model does not have many of the constraints and limitations of existing models for ants colony dynamics and takes into account the distinctly different behaviors exhibited in nature by ant foragers in search of food and food ferrying ants. Numerical simulations based on the model show trail formation in foraging ant colonies to be an emergent phenomenon and, in particular, replicate behavior observed in experiments involving the species P. megacephala. The results have broader implications for the study of randomness in chemotactic models. Potential applications include the developments of novel algorithms for stochastic search in engineered complex systems such as robotic swarms.

  3. Jeans type analysis of chemotactic collapse

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri; Sire, Clément

    2008-07-01

    We perform a linear dynamical stability analysis of a general hydrodynamic model of chemotactic aggregation [P.H. Chavanis, C. Sire, Physica A 384 (2007) 199]. Specifically, we study the stability of an infinite and homogeneous distribution of cells against “chemotactic collapse”. We discuss the analogy between the chemotactic collapse of biological populations and the gravitational collapse (Jeans instability) of self-gravitating systems. Our hydrodynamic model involves a pressure force which can take into account several effects like anomalous diffusion or the fact that the organisms cannot interpenetrate. We also take into account the degradation of the chemical which leads to a shielding of the interaction like for a Yukawa potential. Finally, our hydrodynamic model involves a friction force which quantifies the importance of inertial effects. In the strong friction limit, we obtain a generalized Keller-Segel model similar to the generalized Smoluchowski-Poisson system describing self-gravitating Langevin particles. For small frictions, we obtain a hydrodynamic model of chemotaxis similar to the Euler-Poisson system describing a self-gravitating barotropic gas. We show that an infinite and homogeneous distribution of cells is unstable against chemotactic collapse when the “velocity of sound” in the medium is smaller than a critical value. We study in detail the linear development of the instability and determine the range of unstable wavelengths, the growth rate of unstable modes and the damping rate, or the pulsation frequency, of the stable modes as a function of the friction parameter and shielding length. For specific equations of state, we express the stability criterion in terms of cell density.

  4. The influence of chemotactic factors on neutrophil adhesiveness.

    PubMed

    O'Flaherty, J T; Kreutzer, D L; Ward, P A

    1978-03-01

    The ability of several chemotactic factors to alter polymorphonuclear neutrophil (PMN) adhesiveness to nylon fibers was studied. Partly purified bacterial chemotactic factor, the isolated chemotactic fragment of human C5, and the chemotactic synthetic tripeptide, formyl-methionyl-leucyl-phenylalanine, transiently enhanced the nylon fiber adhesiveness of rabbit peritoneal PMSs. The capacity of these chemotactic factors to augment PMN adherence closely paralleled their ability to aggregate PMNs in suspension and to induce neutropenia when infused into rabbits. However, at least a portion of the adhreence-augmenting capacity of these agents was independent of their ability to induce PMN aggregation. Thus, chemotactic factors appear to transiently enhance PMN adhesiveness to a variety of surfaces. This hyper-adhesiveness may underlie the augmented nylon fiber adherence, aggregation, and neutropenia induced by these factors. PMID:680949

  5. A chemotactic inhibitor in synovial fluid.

    PubMed Central

    Matzner, Y; Partridge, R E; Babior, B M

    1983-01-01

    Synovial fluid was found to contain an inhibitor of neutrophil chemotaxis. The activity of this inhibitor was masked in native synovial fluid, but could be detected in fluid in which complement had been deactivated by mild heating. The inhibitor was most effective against the chemotactic activity of zymosan-activated serum (C5ades arg). It had little effect when N-formyl-methionyl-leucyl-phenylalanine served as chemoattractant. Inhibition was not the result of a direct effect on the neutrophils, since incubation of cells with synovial fluid did not alter their chemotactic response. The inhibitory activity was destroyed by boiling the synovial fluid or treating it with trypsin, suggesting that it is a protein (or proteins); it was not affected by hyaluronidase treatment. Gel filtration revealed that the inhibitor was present in native as well as decomplemented synovial fluid, and that its molecular weight was in the vicinity of 25,000. It is proposed that this inhibitory activity plays a role in the regulation of the inflammatory response in joints. PMID:6840801

  6. Investigating Chemotactic Potential Within Crustal Fluid Communities

    NASA Astrophysics Data System (ADS)

    Carr, S. A.; Jungbluth, S.; Lin, H. T.; Rappe, M. S.; Orcutt, B.

    2014-12-01

    The oceanic crust constitutes, possibly, the largest but most inaccessible habitat on Earth. Exchange of fluid between the permeable crustal environment and overlying sediments and bottom seawater transports electron donors and acceptors, which create redox gradients exploitable by microbial life. While the presence of microbial communities within the oceanic crust is strongly suggested, the structure of these communities, and survival mechanisms used within the hydrothermally-active basement aquifer remain unclear. Recently, crustal fluids from two subsurface borehole observatories (IODP CORKs U1362A and U1362B), located on the eastern flank of Juan de Fuca Ridge, were collected for both single cell genomic and metagenomic analyses. Both techniques revealed an abundance of motility and chemotactic genes. Single-cell amplified genomes (SAGs) classified as Marine Benthic Group E had relatively more motility and taxis genes than any other publically available archaeal SAG. Furthermore, metagenomes from these sites had 3.5 times as many motility and taxis genes than those from sedimentary environments. Many of the detected chemotactic genes (such as tsr and aer) are known to monitor electron flow through the electron transport system, thereby serving as "energy receptors," which direct organisms to the most fitting redox zone. Considering fluid advection occurring within the oceanic crust, the observation of chemotaxis suggests an adaptive lifestyle for crustal microbes.

  7. Chemotactic decision making in swimming microorganisms

    NASA Astrophysics Data System (ADS)

    Salek, M. Mehdi; Guasto, Jeffrey S.; Stocker, Roman

    2014-11-01

    Swimming cells are often guided by chemical gradients (``chemotaxis'') to search for nutrients, hosts, and mates, and to avoid predators and noxious substances. It remains unclear, however, how variable the chemotactic abilities of cells are among cells of one species, and whether there are better ``decision makers'' within a population. Inspired by studies in macro-organism ecology, we fabricated a microfluidic ``T-maze'' in which marine bacteria are subjected to a chemical attractant gradient at each of a series of consecutive T-junctions. We used video microscopy to capture the motion of thousands of bacteria as they migrate up or down the gradient at each subsequent junction. This approach provides detailed statistics at both the single-cell and population levels, while simultaneously sorting the cells by chemotactic ability. Using a range of bacteria, we demonstrate how the microfluidic T-maze allows us to sort the better decision-making cells in the population, opening the door for improved efficiency of a range of microbial processes in nature and industry.

  8. Swimming, swarming, twitching, and chemotactic responses of Cupriavidus metallidurans CH34 and Pseudomonas putida mt2 in the presence of cadmium.

    PubMed

    Shamim, Saba; Rehman, Abdul; Qazi, Mahmood Hussain

    2014-04-01

    To use of microorganisms for bioremediation purposes, the study of their motility behavior toward metals is essential. In the present study, Cupriavidus metallidurans CH34 and Pseudomonas putida mt2 were used as cadmium (Cd)-resistant and -sensitive bacteria, respectively, to evaluate the effects of Cd on their motility behaviors. Potassium morpholinopropane sulfonate (MOPS) buffer was used to observe the motility behavior of both isolates. Movement of mt2 was less in MOPS buffer compared with CH34, likely reflecting the mono-flagellated nature of mt2 and the peritrichous nature of CH34. The swimming, swarming, twitching, and chemotaxis behaviors of mt2 were greater in the presence of glucose than that of Cd. mt2 exhibited negative motility behaviors when exposed to Cd, but the opposite effect was seen in CH34. Cd was found to be a chemorepellent for mt2 but a chemoattractant for CH34, suggesting that CH34 is a potential candidate for metal (Cd) bioremediation. PMID:24306627

  9. Chemotactic selection of pollutant degrading soil bacteria

    DOEpatents

    Hazen, T.C.

    1991-03-04

    A method is described for identifying soil microbial strains which may be bacterial degraders of pollutants. This method includes: Placing a concentration of a pollutant in a substantially closed container; placing the container in a sample of soil for a period of time ranging from one minute to several hours; retrieving the container and collecting its contents; microscopically determining the identity of the bacteria present. Different concentrations of the pollutant can be used to determine which bacteria respond to each concentration. The method can be used for characterizing a polluted site or for looking for naturally occurring biological degraders of the pollutant. Then bacteria identified as degraders of the pollutant and as chemotactically attracted to the pollutant are used to innoculate contaminated soil. To enhance the effect of the bacteria on the pollutant, nutrients are cyclicly provided to the bacteria then withheld to alternately build up the size of the bacterial colony or community and then allow it to degrade the pollutant.

  10. Chemotactic Motility of Sperm in Shear

    NASA Astrophysics Data System (ADS)

    Guasto, Jeffrey S.; Riffell, Jeffrey A.; Zimmer, Richard K.; Stocker, Roman

    2011-11-01

    Chemical gradients are utilized by plants and animals in sexual reproduction to guide swimming sperm cells toward the egg. This process (``chemotaxis''), which can greatly increase the success of fertilization, is subject to interference by fluid flow, both in the bodily conduits of internal fertilizers (e.g. mammals) and in the aquatic environment of external fertilizers (e.g. benthic invertebrates). We studied the biomechanics of chemotaxing sea urchin spermatozoa using microfluidic devices, which allow for the precise and independent control of attractant gradients and fluid shear. We captured swimming trajectories and flagellar beat patterns using high-speed video-microscopy, to detect chemotactic responses and measure the effect of fluid forces on swimming. This work will ultimately help us to understand how swimming sperm cells actively navigate natural chemoattractant gradients for successful fertilization.

  11. Collective Dynamics of Dividing Chemotactic Cells

    NASA Astrophysics Data System (ADS)

    Gelimson, Anatolij; Golestanian, Ramin

    2015-01-01

    The large scale behavior of a population of cells that grow and interact through the concentration field of the chemicals they secrete is studied using dynamical renormalization group methods. The combination of the effective long-range chemotactic interaction and lack of number conservation leads to a rich variety of phase behavior in the system, which includes a sharp transition from a phase that has moderate (or controlled) growth and regulated chemical interactions to a phase with strong (or uncontrolled) growth and no chemical interactions. The transition point has nontrivial critical exponents. Our results might help shed light on the interplay between chemical signaling and growth in tissues and colonies, and in particular on the challenging problem of cancer metastasis.

  12. Chemotactic selection of pollutant degrading soil bacteria

    DOEpatents

    Hazen, Terry C.

    1994-01-01

    A method for identifying soil microbial strains which may be bacterial degraders of pollutants comprising the steps of placing a concentration of a pollutant in a substantially closed container, placing the container in a sample of soil for a period of time ranging from one minute to several hours, retrieving the container, collecting the contents of the container, and microscopically determining the identity of the bacteria present. Different concentrations of the pollutant can be used to determine which bacteria respond to each concentration. The method can be used for characterizing a polluted site or for looking for naturally occurring biological degraders of the pollutant. Then bacteria identified as degraders of the pollutant and as chemotactically attracted to the pollutant are used to inoculate contaminated soil. To enhance the effect of the bacteria on the pollutant, nutrients are cyclicly provided to the bacteria then withheld to alternately build up the size of the bacterial colony or community and then allow it to degrade the pollutant.

  13. Secretion of monocyte chemotactic activity by alveolar macrophages.

    PubMed Central

    Denholm, E. M.; Wolber, F. M.; Phan, S. H.

    1989-01-01

    The purpose of this study was to determine if alveolar macrophages (AMs) are a source of monocyte chemoattractants and the role bleomycin interaction with AMs may play in the recruitment of monocytes to the lung in a rodent model of bleomycin-induced pulmonary fibrosis. AMs isolated from rats with bleomycin-induced fibrosis secreted significantly greater amounts of monocyte chemoattractants than those isolated from normal rats. When AMs from normal rats were stimulated with bleomycin in vitro, monocyte chemotactic activity was secreted into the medium. Chemotactic activity secretion by AM stimulated with 0.01 to 0.1 micrograms/ml bleomycin was significantly higher than that of cells incubated in medium alone. This activity was truly chemotactic for monocytes, but caused only minimal migration of normal AMs. Bleomycin itself at concentrations of 1 pg/ml to 10 micrograms/ml had no monocyte chemoattractant activity. Characterization of the chemotactic activity in conditioned media (CM) from bleomycin-stimulated AM demonstrated that the major portion of the activity bound to gelatin, was heterogeneous, with estimated molecular weights of 20 to 60 kd, and was inactivated by specific antifibronectin antibody. These findings suggest that fibronectin fragments are primarily responsible for the monocyte chemotactic activity secreted by AMs. Through increased secretion of such chemotactic substances, AMs could play a key role in the recruitment of peripheral blood monocytes into the lung in inflammatory lung disease and fibrosis. PMID:2476935

  14. Aerobic kinetoplastid flagellate Phytomonas does not require heme for viability

    PubMed Central

    Kořený, Luděk; Sobotka, Roman; Kovářová, Julie; Gnipová, Anna; Flegontov, Pavel; Horváth, Anton; Oborník, Miroslav; Ayala, Francisco J.; Lukeš, Julius

    2012-01-01

    Heme is an iron-coordinated porphyrin that is universally essential as a protein cofactor for fundamental cellular processes, such as electron transport in the respiratory chain, oxidative stress response, or redox reactions in various metabolic pathways. Parasitic kinetoplastid flagellates represent a rare example of organisms that depend on oxidative metabolism but are heme auxotrophs. Here, we show that heme is fully dispensable for the survival of Phytomonas serpens, a plant parasite. Seeking to understand the metabolism of this heme-free eukaryote, we searched for heme-containing proteins in its de novo sequenced genome and examined several cellular processes for which heme has so far been considered indispensable. We found that P. serpens lacks most of the known hemoproteins and does not require heme for electron transport in the respiratory chain, protection against oxidative stress, or desaturation of fatty acids. Although heme is still required for the synthesis of ergosterol, its precursor, lanosterol, is instead incorporated into the membranes of P. serpens grown in the absence of heme. In conclusion, P. serpens is a flagellate with unique metabolic adaptations that allow it to bypass all requirements for heme. PMID:22355128

  15. Aerobic kinetoplastid flagellate Phytomonas does not require heme for viability.

    PubMed

    Kořený, Luděk; Sobotka, Roman; Kovářová, Julie; Gnipová, Anna; Flegontov, Pavel; Horváth, Anton; Oborník, Miroslav; Ayala, Francisco J; Lukeš, Julius

    2012-03-01

    Heme is an iron-coordinated porphyrin that is universally essential as a protein cofactor for fundamental cellular processes, such as electron transport in the respiratory chain, oxidative stress response, or redox reactions in various metabolic pathways. Parasitic kinetoplastid flagellates represent a rare example of organisms that depend on oxidative metabolism but are heme auxotrophs. Here, we show that heme is fully dispensable for the survival of Phytomonas serpens, a plant parasite. Seeking to understand the metabolism of this heme-free eukaryote, we searched for heme-containing proteins in its de novo sequenced genome and examined several cellular processes for which heme has so far been considered indispensable. We found that P. serpens lacks most of the known hemoproteins and does not require heme for electron transport in the respiratory chain, protection against oxidative stress, or desaturation of fatty acids. Although heme is still required for the synthesis of ergosterol, its precursor, lanosterol, is instead incorporated into the membranes of P. serpens grown in the absence of heme. In conclusion, P. serpens is a flagellate with unique metabolic adaptations that allow it to bypass all requirements for heme. PMID:22355128

  16. Electrochemical monitoring systems of demembranated flagellate algal motility for ATP sensing.

    PubMed

    Shitanda, Isao; Tanaka, Koji; Hoshi, Yoshinao; Itagaki, Masayuki

    2014-02-21

    The ATP-induced behavior of the unicellular flagellate alga Chlamydomonas reinhardtii was recorded as changes in the redox currents for a coexisting redox marker. The ATP concentration was estimated using the presented compact electrochemical system, which is based on monitoring of the motility of the flagellates. PMID:24336166

  17. Flagellation of Pseudomonas aeruginosa in newly divided cells

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Lee, Calvin; Anda, Jaime; Wong, Gerard

    2015-03-01

    For monotrichous bacteria, Pseudomonas aeruginosa, after cell division, one daughter cell inherits the old flagellum from its mother cell, and the other grows a new flagellum during or after cell division. It had been shown that the new flagellum grows at the distal pole of the dividing cell when the two daughter cells haven't completely separated. However, for those daughter cells who grow new flagella after division, it still remains unknown at which pole the new flagellum will grow. Here, by combining our newly developed bacteria family tree tracking techniques with genetic manipulation method, we showed that for the daughter cell who did not inherit the old flagellum, a new flagellum has about 90% chances to grow at the newly formed pole. We proposed a model for flagellation of P. aeruginosa.

  18. 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).

  19. Chemotactic cytokines and inflammation. Biological properties of the lymphocyte and monocyte chemotactic factors ELCF, MCAF and IL-8.

    PubMed

    Zachariae, C O

    1993-01-01

    This thesis discusses the phenotypic characteristics of different inflammatory dermatological diseases and sets this into context with the specific chemotactic ability of different cytokines. It further discusses the biological properties of different chemotactic cytokines and their relevance in certain inflammatory diseases. The term chemotaxis was introduced in 1884 by Pfeffer, who described it as directional migration of leukocytes along a gradient. Regular studies of chemotaxis were, however, not possible until 1962 when Boyden developed the chemotaxis chamber technique. This test has since then been improved, and it is now possible to define and characterize chemoattractants and examine the special chemotactic behavior of leukocytes. We investigated T lymphocyte responses towards different chemoattractants using a modified Boyden chamber technique and found that approximately 50% of normal individuals have cells which respond whereas T-cells from the remaining persons did not respond. We therefore chose human T lymphocytic cell lines as target cells for chemotaxis screening to avoid inter-individual variations among donors. T lymphocytic infiltrates dominated by CD4+, CD45R0+ memory T cells are characteristic for many dermatological inflammatory diseases. We have therefore performed experiments to evaluate whether an earlier described epidermal lymphocyte chemotactic factor (ELCF) from skin overlying a tuberculin skin reaction in addition with other cytokines specifically attracts different subsets of lymphocytes. ELCF which probably reflects a mixture of different epidermal T lymphocyte chemotactic factors rather than a single factor was shown to specifically attract CD4+, CD45R0+ T lymphocytes in contrast to fMLP, IL-8, C5a and LTB4, which induced equal chemotaxis for both CD4+ and CD8+ T lymphocytes. A newly described inhibitory cytokine IL-10 selectively attracted the CD8+ subpopulation of T lymphocytes, and it is suggested that IL-10 could be an important

  20. Expression and Characterization of Recombinant Campylobacter jejuni Chemotactic Proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Expression and Characterization of Recombinant Campylobacter jejuni Chemotactic Proteins Hung-Yueh Yeh*, Kelli L. Hiett, John E. Line, Brian B. Oakley and Bruce S. Seal, Poultry Microbiological Safety Research Unit, Richard B. Russell Agricultural Research Center, Agricultural Research Service, Uni...

  1. Chemotactic factors of Flavobacterium columnare to skin mucus of healthy channel catfish (Ictalurus punctatus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To gain insight into chemotactic factors involved in chemotaxis, we exposed a virulent strain of Flavobacterium columnare to various treatments followed by analysis of its chemotactic activity. Chemotactic activity of F. columnare was significantly (p < 0.05) inhibited when cells were pretreated by ...

  2. Chemotactic factors of Flavobacterium columnare to skin mucus of healthy channel catfish (Ictalurus punctatus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To gain insight into chemotactic factors involved in chemotaxis, we exposed a virulent strain of Flavobacterium columnare to various treatments followed by analysis of its chemotactic activity. The chemotactic activity of F. columnare was significantly (p < 0.05) inhibited when cells were pretreated...

  3. Monocyte chemotactic protein-1 (MCP-1), -2, and -3 are chemotactic for human T lymphocytes.

    PubMed Central

    Taub, D D; Proost, P; Murphy, W J; Anver, M; Longo, D L; van Damme, J; Oppenheim, J J

    1995-01-01

    Monocyte chemotactic protein (MCP)-1, -2, and -3 all have been shown to induce monocyte/macrophage migration in vitro and MCP-1, also known as MCAF, chemoattracts basophils and mast cells. We report here that natural MCP-1 as well as synthetic preparations of MCP-2 and MCP-3 stimulate significant in vitro chemotaxis of human peripheral blood T lymphocytes. This MCP-induced migration was dose-dependent and directional, but not chemokinetic. Phenotypic analysis of the T cell population responsive to MCP-1, MCP-2, and MCP-3 demonstrates that both CD4+ and CD8+ T cells migrated in response to these chemokines. Similar results were observed using human CD4+ and CD8+ T cell clones. Neutralizing antisera to MCAF or MCP-2 abrogated T cell migration in response to MCP-1 and MCP-2, respectively, but not to RANTES. Subcutaneous administration of purified MCP-1 into the hind flanks of SCID mice engrafted with human peripheral blood lymphocytes (PBL) induced significant human CD3+ T cell infiltration into the site of injection at 4 h. These results demonstrate that MCP-1, MCP-2, and MCP-3 are inflammatory mediators that specifically stimulate the directional migration of T cells as well as monocytes and may play an important role in immune cell recruitment into sites of antigenic challenge. Images PMID:7883984

  4. [Eye witnesses and the flagellants in the year 1349].

    PubMed

    Jansen-Sieben, R

    1999-01-01

    Deeply affected and often desperately afraid, many contemporaries recorded their observations and emotions. These reports--no matter how obviously subjective they sometimes were--provide valuable information about what happened during the plague pandemic of 1348-1350. Thus many of our fellow countrymen left behind a direct testimony: Bartholomew of Bruges, a canon in Andenne; Gilles li Muisis, the abbot of Saint Martin in Tournai; Ludovicus Sanctus of Beringen; Simon de Couvin, a canon in Liège; Jan van Boendale, an alderman's clerk in Antwerp; John of Burgundy (also known as John of Mandeville), professor of medicine in Liège; but also texts in Middle Dutch that were not known up to now, and therefore not published, such as the important thesis by Arent Schryver, licentiate in medicine (see next article); an account in verse in the Brabant Chronicle, as well as contemporary testimonies in a different language that have been translated into our language, such as that by John of Eschinden, Johannes de Rupescissa or Guy de Chauliac (who had had the plague himself). They describe the precautions, the causes (God, a comet, an eclipse of the sun, the polluted water, the planets, the air), the symptoms, the social groups most likely to be affected (the youth, the lower classes, the clergy), the high mortality, the problems of hygiene,the social and administrative chaos, the general panic, the flight of countless people. One of the most virulent reactions led to the emergence of the flagellant sect. They originated from Hungary and advanced in an unstoppable advance with a growing number of followers as far as our country, singing, praying, dancing and flaying themselves until they drew blood. We only recently discovered what they sang in Dutch: very recently, a unique roll of parchment was discovered that they carried in their processions, and that contains the text of their songs and a flagellant sermon. The existence of this valuable document and its contents are

  5. Effect of flagellates on free-living bacterial abundance in an organically contaminated aquifer

    USGS Publications Warehouse

    Kinner, N.E.; Harvey, R.W.; Kazmierkiewicz-Tabaka, M.

    1997-01-01

    Little is known about the role of protists in the saturated subsurface. Porous media microcosms containing bacteria and protists, were used to determine whether flagellates from an organically contaminated aquifer could substantively affect the number of free- living bacteria (FLB). When flagellates were present, the 3-40% maximum breakthrough of fluorescent y labelled FLB injected into the microcosms was much lower than the 60-130% observed for killed controls Grazing and clearance rates (3-27 FLB flag-1 h-1 and 12-23 nI flag-1 h-1, respectively) calculated from the data were in the range reported for flagellates in other aqueous environments. The data provide evidence that flagellate bacterivory is an important control on groundwater FLB populations.

  6. Bleomycin-induced Flagellate Erythema: A Rare and Unique Drug Rash

    PubMed Central

    Changal, KH; Raina, H; Changal, QH; Raina, M

    2014-01-01

    ABSTRACT Bleomycin-induced flagellate erythema is a rare rash associated with the use of the drug. The rash has a characteristic and intermingled lacy appearance as if it has been whipped. Lack of detoxifying enzymes for bleomycin in the skin makes it a vulnerable site for the adverse effects of bleomycin, along with the lungs. We report the case of young girl with germ cell tumour who developed bleomycin-induced flagellate erythema. PMID:25867573

  7. Zooplankton Feeding on the Nuisance Flagellate Gonyostomum semen

    PubMed Central

    Johansson, Karin S. L.; Vrede, Tobias; Lebret, Karen; Johnson, Richard K.

    2013-01-01

    The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation. In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and lakes that rarely experience blooms, we found that Eudiaptomus gracilis and Holopedium gibberum fed on G. semen at high rates, whereas Daphnia cristata and Ceriodaphnia spp. did not. Grazing rates of E. gracilis were similar between bloom-lakes and lakes with low biomass of G. semen, indicating that the ability to feed on G. semen was not a result of local adaptation. The high grazing rates of two of the taxa in our experiment imply that some of the nutrients and energy taken up by G. semen can be transferred directly to higher trophic levels, although the predominance of small cladocerans during blooms may limit the importance of G. semen as a food resource. Based on grazing rates and previous observations on abundances of E. gracilis and H. gibberum, we conclude that there is a potential for grazer control of G. semen and discuss why blooms of G. semen still occur. PMID:23667489

  8. Acute colitis produced by chemotactic peptides in rats and mice.

    PubMed Central

    Chester, J. F.; Ross, J. S.; Malt, R. A.; Weitzman, S. A.

    1985-01-01

    Colonic inflammation was produced in rats and mice by peptides chemotactic for polymorphonuclear leukocytes. Instillation of formylmethionyl-leucyl-phenylalanine (FMLP) and formylnorleucyl-leucyl-phenylalanine (FNLP) into isolated segments of rat colon caused marked mucosal edema and polymorphonuclear leukocyte infiltration within 2 hours. Higher concentrations of FNLP caused ulceration and necrosis as well. Formylmethionine (FMet), a compound with less chemotactic activity, caused much less inflammation. In mice, rectal instillation of FNLP caused dose-dependent acute mucosal inflammation which persisted for longer than 12 hours. Twice-weekly rectal instillation of FNLP provided a model of colitis based on neutrophil chemotaxis. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:4061566

  9. Interactions and Collective Behaviour of Chemotactic Active Colloids

    NASA Astrophysics Data System (ADS)

    Saha, Suropriya; Hablani, Surbhi; Golestanian, Ramin; Ramaswamy, Sriram

    2015-03-01

    Artificial realizations of motility point in the direction of a new paradigm in engineering, through the design of emergent behavior by manipulating properties at the scale of the individual components. Catalytic colloidal swimmers are a particularly promising example of such systems. Here we present a comprehensive theoretical description of gradient-sensing of an individual swimmer, leading controllably to chemotactic or anti-chemotactic behavior. We use it to study the scattering of such a swimmer off a reactant source and construct a framework for studying their two body interactions and finally their collective behavior. We find that both the positional and the orientational degrees of freedom of the active colloids can exhibit condensation, signalling formation of clusters and asters. We present prescriptions for how to tune the surface properties of the colloids during fabrication to achieve each type of behavior. We further study the athermal fluctuations of a pointed tracer particle in a bath of such swimmers.

  10. Collective behavior of chemotactic colloids: clusters, asters and oscillations

    NASA Astrophysics Data System (ADS)

    Saha, Suropriya; Golestanian, Ramin; Ramaswamy, Sriram

    2014-03-01

    Catalytic colloidal swimmers are a particularly promising example of systems that emulate properties of living matter, such as motility, gradient-sensing, signaling and replication. Here we present a comprehensive theoretical description of dynamics of an individual patterned catalytic colloid, leading controllably to chemotactic or anti-chemotactic behavior. We find that both the positional and the orientational degrees of freedom of the active colloids can exhibit condensation, signaling formation of clusters and asters. The kinetics of catalysis introduces a natural control parameter for the range of the interaction mediated by the diffusing chemical species. For various regimes in parameter space in the long-ranged limit our system displays precise analogs to gravitational collapse, plasma oscillations and electrostatic screening. We present prescriptions for how to tune the surface properties of the colloids during fabrication to achieve each type of behavior.

  11. Controlling interneuron activity in Caenorhabditis elegans to evoke chemotactic behaviour.

    PubMed

    Kocabas, Askin; Shen, Ching-Han; Guo, Zengcai V; Ramanathan, Sharad

    2012-10-11

    Animals locate and track chemoattractive gradients in the environment to find food. With its small nervous system, Caenorhabditis elegans is a good model system in which to understand how the dynamics of neural activity control this search behaviour. Extensive work on the nematode has identified the neurons that are necessary for the different locomotory behaviours underlying chemotaxis through the use of laser ablation, activity recording in immobilized animals and the study of mutants. However, we do not know the neural activity patterns in C. elegans that are sufficient to control its complex chemotactic behaviour. To understand how the activity in its interneurons coordinate different motor programs to lead the animal to food, here we used optogenetics and new optical tools to manipulate neural activity directly in freely moving animals to evoke chemotactic behaviour. By deducing the classes of activity patterns triggered during chemotaxis and exciting individual neurons with these patterns, we identified interneurons that control the essential locomotory programs for this behaviour. Notably, we discovered that controlling the dynamics of activity in just one interneuron pair (AIY) was sufficient to force the animal to locate, turn towards and track virtual light gradients. Two distinct activity patterns triggered in AIY as the animal moved through the gradient controlled reversals and gradual turns to drive chemotactic behaviour. Because AIY neurons are post-synaptic to most chemosensory and thermosensory neurons, it is probable that these activity patterns in AIY have an important role in controlling and coordinating different taxis behaviours of the animal. PMID:23000898

  12. Singly Flagellated Pseudomonas aeruginosa Chemotaxes Efficiently by Unbiased Motor Regulation

    PubMed Central

    Cai, Qiuxian; Li, Zhaojun; Ouyang, Qi

    2016-01-01

    ABSTRACT Pseudomonas aeruginosa is an opportunistic human pathogen that has long been known to chemotax. More recently, it has been established that chemotaxis is an important factor in the ability of P. aeruginosa to make biofilms. Genes that allow P. aeruginosa to chemotax are homologous with genes in the paradigmatic model organism for chemotaxis, Escherichia coli. However, P. aeruginosa is singly flagellated and E. coli has multiple flagella. Therefore, the regulation of counterclockwise/clockwise flagellar motor bias that allows E. coli to efficiently chemotax by runs and tumbles would lead to inefficient chemotaxis by P. aeruginosa, as half of a randomly oriented population would respond to a chemoattractant gradient in the wrong sense. How P. aeruginosa regulates flagellar rotation to achieve chemotaxis is not known. Here, we analyze the swimming trajectories of single cells in microfluidic channels and the rotations of cells tethered by their flagella to the surface of a variable-environment flow cell. We show that P. aeruginosa chemotaxes by symmetrically increasing the durations of both counterclockwise and clockwise flagellar rotations when swimming up the chemoattractant gradient and symmetrically decreasing rotation durations when swimming down the chemoattractant gradient. Unlike the case for E. coli, the counterclockwise/clockwise bias stays constant for P. aeruginosa. We describe P. aeruginosa’s chemotaxis using an analytical model for symmetric motor regulation. We use this model to do simulations that show that, given P. aeruginosa’s physiological constraints on motility, its distinct, symmetric regulation of motor switching optimizes chemotaxis. PMID:27048795

  13. Lypd8 promotes the segregation of flagellated microbiota and colonic epithelia.

    PubMed

    Okumura, Ryu; Kurakawa, Takashi; Nakano, Takashi; Kayama, Hisako; Kinoshita, Makoto; Motooka, Daisuke; Gotoh, Kazuyoshi; Kimura, Taishi; Kamiyama, Naganori; Kusu, Takashi; Ueda, Yoshiyasu; Wu, Hong; Iijima, Hideki; Barman, Soumik; Osawa, Hideki; Matsuno, Hiroshi; Nishimura, Junichi; Ohba, Yusuke; Nakamura, Shota; Iida, Tetsuya; Yamamoto, Masahiro; Umemoto, Eiji; Sano, Koichi; Takeda, Kiyoshi

    2016-04-01

    Colonic epithelial cells are covered by thick inner and outer mucus layers. The inner mucus layer is free of commensal microbiota, which contributes to the maintenance of gut homeostasis. In the small intestine, molecules critical for prevention of bacterial invasion into epithelia such as Paneth-cell-derived anti-microbial peptides and regenerating islet-derived 3 (RegIII) family proteins have been identified. Although there are mucus layers providing physical barriers against the large number of microbiota present in the large intestine, the mechanisms that separate bacteria and colonic epithelia are not fully elucidated. Here we show that Ly6/PLAUR domain containing 8 (Lypd8) protein prevents flagellated microbiota invading the colonic epithelia in mice. Lypd8, selectively expressed in epithelial cells at the uppermost layer of the large intestinal gland, was secreted into the lumen and bound flagellated bacteria including Proteus mirabilis. In the absence of Lypd8, bacteria were present in the inner mucus layer and many flagellated bacteria invaded epithelia. Lypd8(-/-) mice were highly sensitive to intestinal inflammation induced by dextran sulfate sodium (DSS). Antibiotic elimination of Gram-negative flagellated bacteria restored the bacterial-free state of the inner mucus layer and ameliorated DSS-induced intestinal inflammation in Lypd8(-/-) mice. Lypd8 bound to flagella and suppressed motility of flagellated bacteria. Thus, Lypd8 mediates segregation of intestinal bacteria and epithelial cells in the colon to preserve intestinal homeostasis. PMID:27027293

  14. Negative consequences of glacial turbidity for the survival of freshwater planktonic heterotrophic flagellates.

    PubMed

    Sommaruga, Ruben; Kandolf, Georg

    2014-01-01

    Heterotrophic (phagotrophic) flagellates are key components of planktonic food webs in freshwater and marine ecosystems because they are the main consumers of bacteria. Although they are ubiquitous in aquatic ecosystems, they were numerically undetectable in turbid glacier-fed lakes. Here we show that glacial particles had negative effects on the survival and growth of heterotrophic flagellates. The effect of glacial particles was concentration-dependent and was caused by their interference with bacterial uptake rather than by physical damage. These results are the first to reveal why establishment of heterotrophic flagellates populations is hindered in very turbid glacial lakes. Because glaciers are vanishing around the world, recently formed turbid meltwater lakes represent an excellent opportunity to understand the environmental conditions that probably shaped the establishment of lake communities at the end of the last glaciation. PMID:24531332

  15. Collective cell motility promotes chemotactic prowess and resistance to chemorepulsion.

    PubMed

    Malet-Engra, Gema; Yu, Weimiao; Oldani, Amanda; Rey-Barroso, Javier; Gov, Nir S; Scita, Giorgio; Dupré, Loïc

    2015-01-19

    Collective cell migration is a widespread biological phenomenon, whereby groups of highly coordinated, adherent cells move in a polarized fashion. This migration mode is a hallmark of tissue morphogenesis during development and repair and of solid tumor dissemination. In addition to circulating as solitary cells, lymphoid malignancies can assemble into tissues as multicellular aggregates. Whether malignant lymphocytes are capable of coordinating their motility in the context of chemokine gradients is, however, unknown. Here, we show that, upon exposure to CCL19 or CXCL12 gradients, malignant B and T lymphocytes assemble into clusters that migrate directionally and display a wider chemotactic sensitivity than individual cells. Physical modeling recapitulates cluster motility statistics and shows that intracluster cell cohesion results in noise reduction and enhanced directionality. Quantitative image analysis reveals that cluster migration runs are periodically interrupted by transitory rotation and random phases that favor leader cell turnover. Additionally, internalization of CCR7 in leader cells is accompanied by protrusion retraction, loss of polarity, and the ensuing replacement by new leader cells. These mechanisms ensure sustained forward migration and resistance to chemorepulsion, a behavior of individual cells exposed to steep CCL19 gradients that depends on CCR7 endocytosis. Thus, coordinated cluster dynamics confer distinct chemotactic properties, highlighting unexpected features of lymphoid cell migration. PMID:25578904

  16. Global solution for a chemotactic haptotactic model of cancer invasion

    NASA Astrophysics Data System (ADS)

    Tao, Youshan; Wang, Mingjun

    2008-10-01

    This paper deals with a mathematical model of cancer invasion of tissue recently proposed by Chaplain and Lolas. The model consists of a reaction-diffusion-taxis partial differential equation (PDE) describing the evolution of tumour cell density, a reaction-diffusion PDE governing the evolution of the proteolytic enzyme concentration and an ordinary differential equation modelling the proteolysis of the extracellular matrix (ECM). In addition to random motion, the tumour cells are directed not only by haptotaxis (cellular locomotion directed in response to a concentration gradient of adhesive molecules along the ECM) but also by chemotaxis (cellular locomotion directed in response to a concentration gradient of the diffusible proteolytic enzyme). In one space dimension, the global existence and uniqueness of a classical solution to this combined chemotactic-haptotactic model is proved for any chemotactic coefficient χ > 0. In two and three space dimensions, the global existence is proved for small χ/μ (where μ is the logistic growth rate of the tumour cells). The fundamental point of proof is to raise the regularity of a solution from L1 to Lp (p > 1). Furthermore, the existence of blow-up solutions to a sub-model in two space dimensions for large χ shows, to some extent, that the condition that χ/μ is small is necessary for the global existence of a solution to the full model.

  17. Diversity of chemotactic heterotrophic bacteria associated with arctic cyanobacteria.

    PubMed

    Prasad, Sathish; Pratibha, Mambatta Shankaranarayanan; Manasa, Poorna; Buddhi, Sailaja; Begum, Zareena; Shivaji, Sisinthy

    2013-01-01

    The abundance and diversity of chemotactic heterotrophic bacteria associated with Arctic cyanobacteria was determined. The viable numbers ranged between 10(4) and 10(6) cell g(-1) cyanobacterial biomass. A total of 112 morphotypes, representing 22 phylotypes based on their 16S rRNA sequence similarity were isolated from the samples. All the phylotypes were Gram-negative with affiliation to the proteobacterial and bacteroidetes divisions. Among the 22 phylotypes, 14 were chemotactic to glucose. Majority of the phylotypes were psychrotolerant showing growth up to 30 °C. Representatives of Alphaproteobacteria, the genus Flavobacterium and the gammaproteobacterial Alcanivorax sp, were psychrophilic with growth at or below 18 °C. A significant percentage of phylotypes were pigmented (~68 %), rich in unsaturated membrane fatty acids and tolerated pH values and NaCl concentrations between 5.0-8.0 and 0.15-1.0 M, respectively. The percentages of phylotypes producing extracellular cold-active enzymes at 4 °C were amylase (18.18 %), lipase and urease (45.45 %), caseinase (59.09 %) and gelatinase (31.8 %). PMID:23053490

  18. EGFRs mediate chemotactic migration in the developing telencephalon.

    PubMed

    Caric, D; Raphael, H; Viti, J; Feathers, A; Wancio, D; Lillien, L

    2001-11-01

    Epidermal growth factor receptors (EGFRs) have been implicated in the control of migration in the telencephalon, but the mechanism underlying their contribution is unclear. We show that expression of a threshold level of EGFRs confers chemotactic competence in stem cells, neurons and astrocytes in cortical explants. This level of receptor expression is normally achieved by a subpopulation of cells during mid-embryonic development. Cells that express high levels of EGFR are located in migration pathways, including the tangential pathway to the olfactory bulb via the rostral migratory stream (RMS), the lateral cortical stream (LCS) leading to ventrolateral cortex and the radial pathway from proliferative zones to cortical plate. The targets of these pathways express the ligands HB-EGF and/or TGFalpha. To test the idea that EGFRs mediate chemotactic migration these pathways, we increased the size of the population of cells expressing threshold levels of EGFRs in vivo by viral transduction. Our results suggest that EGFRs mediate migration radially to the cortical plate and ventrolaterally in the LCS, but not tangentially in the RMS. Within the bulb, however, EGFRs also mediate radial migration. Our findings suggest that developmental changes in EGFR expression, together with changes in ligand expression regulate the migration of specific populations of cells in the telencephalon by a chemoattractive mechanism. PMID:11684657

  19. Bias in the Gradient Sensing Response of Chemotactic Cells

    PubMed Central

    Skupsky, Ron; McCann, Colin; Nossal, Ralph; Losert, Wolfgang

    2009-01-01

    We apply linear-stability theory and perform perturbation studies to better characterize, and to generate new experimental predictions from, a model of chemotactic gradient sensing in eukaryotic cells. The model uses reaction-diffusion equations to describe 3′ phosphoinositide signaling and its regulation at the plasma membrane. It demonstrates a range of possible gradient-sensing mechanisms and captures such characteristic behaviors as strong polarization in response to static gradients, adaptation to differing mean levels of stimulus, and plasticity in response to changing gradients. An analysis of the stability of polarized steady-state solutions indicates that the model is most sensitive to off-axis perturbations. This biased sensitivity is reflected in responses to localized external stimuli as well, and leads to a clear experimental prediction, namely, that a cell which is polarized in a background gradient will be most sensitive to transient point-source stimuli lying within a range of angles that are oblique with respect to the polarization axis. Stimuli at angles below this range will elicit responses whose directions overshoot the stimulus angle, while responses to stimuli applied at larger angles will undershoot the stimulus angle. We argue that such a bias is likely to be a general feature of gradient sensing in highly motile cells, particularly if they are optimized to respond to small gradients. Finally, an angular bias in gradient sensing might lead to preferred turn angles and zigzag movements of cells moving up chemotactic gradients, as has been noted under certain experimental conditions. PMID:17462672

  20. Clusters, asters, and collective oscillations in chemotactic colloids.

    PubMed

    Saha, Suropriya; Golestanian, Ramin; Ramaswamy, Sriram

    2014-06-01

    The creation of synthetic systems that emulate the defining properties of living matter, such as motility, gradient-sensing, signaling, and replication, is a grand challenge of biomimetics. Such imitations of life crucially contain active components that transform chemical energy into directed motion. These artificial realizations of motility point in the direction of a new paradigm in engineering, through the design of emergent behavior by manipulating properties at the scale of the individual components. Catalytic colloidal swimmers are a particularly promising example of such systems. Here we present a comprehensive theoretical description of gradient-sensing of an individual swimmer, leading controllably to chemotactic or anti-chemotactic behavior, and use it to construct a framework for studying their collective behavior. We find that both the positional and the orientational degrees of freedom of the active colloids can exhibit condensation, signaling formation of clusters and asters. The kinetics of catalysis introduces a natural control parameter for the range of the interaction mediated by the diffusing chemical species. For various regimes in parameter space in the long-ranged limit our system displays precise analogs to gravitational collapse, plasma oscillations, and electrostatic screening. We present prescriptions for how to tune the surface properties of the colloids during fabrication to achieve each type of behavior. PMID:25019785

  1. Clusters, asters, and collective oscillations in chemotactic colloids

    NASA Astrophysics Data System (ADS)

    Saha, Suropriya; Golestanian, Ramin; Ramaswamy, Sriram

    2014-06-01

    The creation of synthetic systems that emulate the defining properties of living matter, such as motility, gradient-sensing, signaling, and replication, is a grand challenge of biomimetics. Such imitations of life crucially contain active components that transform chemical energy into directed motion. These artificial realizations of motility point in the direction of a new paradigm in engineering, through the design of emergent behavior by manipulating properties at the scale of the individual components. Catalytic colloidal swimmers are a particularly promising example of such systems. Here we present a comprehensive theoretical description of gradient-sensing of an individual swimmer, leading controllably to chemotactic or anti-chemotactic behavior, and use it to construct a framework for studying their collective behavior. We find that both the positional and the orientational degrees of freedom of the active colloids can exhibit condensation, signaling formation of clusters and asters. The kinetics of catalysis introduces a natural control parameter for the range of the interaction mediated by the diffusing chemical species. For various regimes in parameter space in the long-ranged limit our system displays precise analogs to gravitational collapse, plasma oscillations, and electrostatic screening. We present prescriptions for how to tune the surface properties of the colloids during fabrication to achieve each type of behavior.

  2. Bleomycin-Induced Flagellate Erythema in a Patient Diagnosed with Ovarian Yolk Sac Tumor

    PubMed Central

    Boussios, Stergios; Moschetta, Michele; McLachlan, Jennifer; Banerjee, Susana

    2015-01-01

    Flagellate linear hyperpigmentation can rarely be caused by the chemotherapy agent, bleomycin. Herein, we describe the case of a 20-year-old woman treated with bleomycin for an ovarian yolk sac tumor and review the prominent features of this form of dermatitis. PMID:26798532

  3. Bleomycin-Induced Flagellate Erythema in a Patient Diagnosed with Ovarian Yolk Sac Tumor.

    PubMed

    Boussios, Stergios; Moschetta, Michele; McLachlan, Jennifer; Banerjee, Susana

    2015-01-01

    Flagellate linear hyperpigmentation can rarely be caused by the chemotherapy agent, bleomycin. Herein, we describe the case of a 20-year-old woman treated with bleomycin for an ovarian yolk sac tumor and review the prominent features of this form of dermatitis. PMID:26798532

  4. Grazing on Microcystis aeruginosa and degradation of microcystins by the heterotrophic flagellate Diphylleia rotans.

    PubMed

    Mohamed, Zakaria A; Al-Shehri, Abdultahman M

    2013-10-01

    Cyanobacterial toxins can cause damage in aquatic ecosystems worldwide, as well as the poisoning of livestock, plants and humans when ingested in large amounts. Although many studies investigated grazing of harmful cyanobacteria by metazoan plankton, grazing of cyanobacteria by hetertophic flagellates is largely unexplored. This laboratory study investigated grazing of toxic Microcystis aeruginosa by the heterotrophic flagellate Diphylleia rotans isolated from a Saudi hypertrophic lake. D. rotans was able to feed on M. aeruginosa with estimated ingestion (10.2 to 16.5 prey flagellate (-1)d(-1)) and specific growth rates (0.71 to 0.99d(-1)) differed with the increase in the initial density of the flagellate. Grazing increased microcystin production within Microcystis cells during first two days of incubation, and afterwards induced the release of these toxins into the medium. The concentrations of releasing microcystin were strongly reduced in grazing-treated cultures compared to controls, indicating the degradation of microcystins by D. rotans growing under axenic conditions. Taken these results, D. rotans can play an important role in the reduction of Microcystis biomass and microcystin toxins, and thus could be used as a safe bioagent for the biocontrol of harmful algal blooms in aquatic environments. PMID:23856124

  5. Contrasting bacterial strategies to coexist with a flagellate predator in an experimental microbial assemblage.

    PubMed

    Pernthaler, J; Posch, T; Simek, K; Vrba, J; Amann, R; Psenner, R

    1997-02-01

    We studied predator-induced changes within a slowly growing mixed microbial assemblage that was sustained by algal exudates in a continuous cultivation system. In situ hybridization with fluorescent monolabeled oligonucleotide probes was used for a tentative community analysis. This method also allowed us to quantify the proportions of predators with ingested bacteria of different taxonomic groups. In addition, we determined grazing rates on bacteria with fluorescently labelled prey. Bacteria belonging to the alpha and beta subdivisions of the phylum Proteobacteria ((alpha)- and (beta)-Proteobacteria, respectively) showed very different responses to the addition of a bacterivorous flagellate, Bodo saltans. Within one day, filamentous protist-inedible bacteria developed; these belonged to the (beta)-Proteobacteria and constituted between 8.7 and 34% of bacteria from this subgroup. Total abundance of (beta)-Proteobacteria decreased from 3.05 x 10(sup6) to 0.23 x 10(sup6) cells ml(sup-1), and estimated cell division rates were low. Other morphologically inconspicuous protist-edible bacteria belonging to the (alpha)-Proteobacteria were found to respond to predation by an increase in growth rate. Although these bacteria were heavily grazed upon, as on average >85% of flagellate cells had ingested (alpha)-Proteobacteria, they numerically dominated after the addition of B. saltans (mean, 1.35 x 10(sup6) cells ml(sup-1)). It was thus mainly those fast-dividing strains of (alpha)-Proteobacteria that supported the growth of the flagellate population. We conclude that bacteria in mixed assemblages can adopt at least two distinct strategies as a reaction to intense flagellate predation: to outgrow predation pressure or to develop inedible, inactive filaments. Since these strategies occurred within 24 h after the addition of the flagellate, we hypothesize that chemical stimuli released by the predator may have triggered bacterial responses. PMID:16535516

  6. Chemotactic-based adaptive self-organization during colonial development

    NASA Astrophysics Data System (ADS)

    Cohen, Inon; Czirók, Andras; Ben-Jacob, Eshel

    1996-02-01

    Bacterial colonies have developed sophisticated modes of cooperative behavior which enable them to respond to adverse growth conditions. It has been shown that such behavior can be manifested in the development of complex colonial patterns. Certain bacterial species exhibit formation of branching patterns during colony development. Here we present a generic model to describe such patterning of swimming (tumbling) bacteria on agar surfaces. The model incorporates: (1) food diffusion, (2) reproduction and sporulation of the cells, (3) movement of the bacterial cells within a self-produced wetting fluid and (4) chemotactic signaling. As a plausible explanation for transitions between different branching morphologies, we propose an interplay between chemotaxis towards food, self-produced short range chemoattractant and long range chemorepellent.

  7. Controlling neural activity in Caenorhabditis elegans to evoke chemotactic behavior

    NASA Astrophysics Data System (ADS)

    Kocabas, Askin; Shen, Ching-Han; Guo, Zengcai V.; Ramanathan, Sharad

    2013-03-01

    Animals locate and track chemoattractive gradients in the environment to find food. With its simple nervous system, Caenorhabditis elegans is a good model system in which to understand how the dynamics of neural activity control this search behavior. To understand how the activity in its interneurons coordinate different motor programs to lead the animal to food, here we used optogenetics and new optical tools to manipulate neural activity directly in freely moving animals to evoke chemotactic behavior. By deducing the classes of activity patterns triggered during chemotaxis and exciting individual neurons with these patterns, we identified interneurons that control the essential locomotory programs for this behavior. Notably, we discovered that controlling the dynamics of activity in just one interneuron pair was sufficient to force the animal to locate, turn towards and track virtual light gradients.

  8. Morphology of two new marine peritrich ciliates from Yellow Sea, Pseudovorticella dingi nov. spec. and P. wangi nov. spec., with supplementary descriptions of P. plicata, P. banatica and P. anomala (Ciliophora, Peritrichia).

    PubMed

    Sun, Ping; Ma, Honggang; Shin, Mann Kyoon; Al-Rasheid, Khaled A S

    2013-08-01

    Two new marine peritrich ciliates, Pseudovorticella dingi nov. spec. and Pseudovorticella wangi nov. spec. were collected from coastal waters of Qingdao, China. Their living morphology, infraciliature and silverline system were studied using light microscopy and silver staining methods. Pseudovorticella dingi is characterized mainly by the apically located contractile vacuole and the presence of pellicular granules. There are 28-36 and 13-18 transverse silverlines above and below the trochal band, respectively. Infundibular polykinety 3 is composed of three rows, with row 1 conspicuously shorter than the other two. P. wangi is distinguished mainly by having two ventrally located contractile vacuoles. There are 17-20 and 9-11 transverse silverlines above and below the trochal band, respectively. Abstomal end of row 1 of infundibular polykinety 3 diverges from the other two and ends alongside row 3 of infundibular polykinety 2. Pseudovorticella plicata, P. banatica, and P. anomala have been described in Sun et al. (2009); we supplement morphometric data and photographs from life and after silver staining of these three species in the present study. PMID:23290863

  9. Flagellated bacteria trace out a parabolic arc under low shear condition

    NASA Astrophysics Data System (ADS)

    Ahn, Yongtae; Hashmi, Sara; Walker, Sharon; Hill, Jane

    2010-03-01

    The measurement and prediction of bacterial transport of bacteria in aquatic systems is of fundamental importance to a variety of fields such as groundwater bioremediation ascending urinary tract infection. The motility of pathogenic bacteria is, however, often missing when considering pathogen translocation prediction. Previously, we reported that flagellated E. coli can translate upstream under low shear flow conditions (Hill et al., 2007). The upstream swimming of flagellated microorganisms depends on hydrodynamic interaction between cell body and surrounding fluid flow. In this study, we use a breathable microfluidic device to image swimming E. coli and P. aeruginosa at a glass surface under low shear flow condition. We find the dominant experimental variables that lead to upstream swimming are: fluid shear, bacterium velocity, and bacterium length. We will present data showing that the sum of forces and torques acting on a bacterium lead to them tracing out a parabolic arc as they turn into the flow to swim upstream.

  10. Discocelis saleuta gen. nov. et sp. nov. (Protista incertae sedis): - A new heterotrophic marine flagellate.

    PubMed

    Vørs, N

    1988-10-01

    The colourless flagellate Discocelis saleuta, a new genus from marine sediments, has been studied by light microscopy and single-cell sectioning for electron microscopy. The cell is discshaped and possesses an anterior velum and two anteriorly inserted unequal flagella. The cell body periphery and the velum are supported by ribbons of microtubules. Three flagellar roots, each of which comprises relatively few microtubules, arise from the flagellar basal bodies. Two of these roots run posteriorly under the ventral cell membrane, whereas the third root mainly runs along the posterior edge of the velum. The cell is further characterized by a microbody-like paranuclear organelle, and by a row of extrusomes bordering the cell periphery. Mitochondria have short tubular cristae. This minute flagellate adheres tightly to sand grains. The ultrastructure is unlike that of any well circumscribed higher order taxon, and the new genus is consequently placed incertae sedis in the kingdom Protista. PMID:23195317

  11. The soil flagellate Heteromita globosa accelerates bacterial degradation of alkylbenzenes through grazing and acetate excretion in batch culture.

    PubMed

    Mattison, R G; Taki, H; Harayama, S

    2005-01-01

    The impact of grazing by soil flagellates Heteromita globosa on aerobic biodegradation of benzene by Pseudomonas strain PS+ was examined in batch culture. Growth of H. globosa on these bacteria obeyed Monod kinetics (mu(max), 0.17 +/- 0.03 h(-1); K(s), 1.1 +/- 0.2 x 10(7) bacteria mL(-1)) and was optimal at a bacteria/ flagellate ratio of 2000. Carbon mass balance showed that 5.2% of total [ring-U-(14)C]benzene fed to bacteria was subsequently incorporated into flagellate biomass. Growth-inhibiting concentrations (IC50) of alkylbenzenes (benzene, toluene, ethylbenzene) were inversely related with their octanol/ water partitioning coefficients, and benzene was least toxic for bacteria and flagellates with IC50 values of 4392 (+/- 167) microM and 2770 (+/- 653) microM, respectively. The first-order rate constant for benzene degradation (k1, 0.48 +/- 0.12 day(-1)) was unaffected by the presence or absence of flagellates in cultures. However, the rate of benzene degradation by individual bacteria averaged three times higher in the presence of flagellates (0.73 +/- 0.13 fmol cell(-1) h(-1)) than in their absence (0.26 +/- 0.03 fmol cell(-1) h(-1)). Benzene degradation also coincided with higher levels of dissolved oxygen and a higher rate of nitrate reduction in the presence of flagellates (p < 0.02). Grazing by flagellates may have increased the availability of dissolved oxygen to a smaller surviving population of bacteria engaged in the aerobic reactions initiating benzene degradation. In addition, flagellates may also have increased the rate of nitrate reduction through the excretion of acetate as an additional electron donor for these bacteria. Indeed, acetate was shown to progressively accumulate in cultures where flagellates grazed on heat-killed bacteria. This study provided evidence that grazing flagellates stimulate bacterial degradation of alkylbenzenes and provide a link for carbon cycling to consumers at higher trophic levels. This may have important

  12. Unlocking the secrets of multi-flagellated propulsion: drawing insights from Tritrichomonas foetus.

    PubMed

    Lenaghan, Scott C; Nwandu-Vincent, Stefan; Reese, Benjamin E; Zhang, Mingjun

    2014-04-01

    In this work, a high-speed imaging platform and a resistive force theory (RFT) based model were applied to investigate multi-flagellated propulsion, using Tritrichomonas foetus as an example. We discovered that T. foetus has distinct flagellar beating motions for linear swimming and turning, similar to the 'run and tumble' strategies observed in bacteria and Chlamydomonas. Quantitative analysis of the motion of each flagellum was achieved by determining the average flagella beat motion for both linear swimming and turning, and using the velocity of the flagella as inputs into the RFT model. The experimental approach was used to calculate the curvature along the length of the flagella throughout each stroke. It was found that the curvatures of the anterior flagella do not decrease monotonically along their lengths, confirming the ciliary waveform of these flagella. Further, the stiffness of the flagella was experimentally measured using nanoindentation, allowing for calculation of the flexural rigidity of T. foetus's flagella, 1.55×10(-21) N m(2). Finally, using the RFT model, it was discovered that the propulsive force of T. foetus was similar to that of sperm and Chlamydomonas, indicating that multi-flagellated propulsion does not necessarily contribute to greater thrust generation, and may have evolved for greater manoeuvrability or sensing. The results from this study have demonstrated the highly coordinated nature of multi-flagellated propulsion and have provided significant insights into the biology of T. foetus. PMID:24478286

  13. Unlocking the secrets of multi-flagellated propulsion: drawing insights from Tritrichomonas foetus

    PubMed Central

    Lenaghan, Scott C.; Nwandu-Vincent, Stefan; Reese, Benjamin E.; Zhang, Mingjun

    2014-01-01

    In this work, a high-speed imaging platform and a resistive force theory (RFT) based model were applied to investigate multi-flagellated propulsion, using Tritrichomonas foetus as an example. We discovered that T. foetus has distinct flagellar beating motions for linear swimming and turning, similar to the ‘run and tumble’ strategies observed in bacteria and Chlamydomonas. Quantitative analysis of the motion of each flagellum was achieved by determining the average flagella beat motion for both linear swimming and turning, and using the velocity of the flagella as inputs into the RFT model. The experimental approach was used to calculate the curvature along the length of the flagella throughout each stroke. It was found that the curvatures of the anterior flagella do not decrease monotonically along their lengths, confirming the ciliary waveform of these flagella. Further, the stiffness of the flagella was experimentally measured using nanoindentation, allowing for calculation of the flexural rigidity of T. foetus's flagella, 1.55×10−21 N m2. Finally, using the RFT model, it was discovered that the propulsive force of T. foetus was similar to that of sperm and Chlamydomonas, indicating that multi-flagellated propulsion does not necessarily contribute to greater thrust generation, and may have evolved for greater manoeuvrability or sensing. The results from this study have demonstrated the highly coordinated nature of multi-flagellated propulsion and have provided significant insights into the biology of T. foetus. PMID:24478286

  14. Comparison of the chemotactic responsiveness of two fibrosarcoma subpopulations of differing malignancy.

    PubMed Central

    Orr, F. W.; Varani, J.; Delikatny, J.; Jain, N.; Ward, P. A.

    1981-01-01

    There are several points of similarity between the processes of cancer metastasis and inflammation. In both, cells circulate in the vasculature, arrest, and cross vessel walls, thereby entering the extravascular tissues. In vitro, leukocytes and some, but not all, tumor cells exhibit chemotaxis. Since the chemotactic response of leukocytes effect their transvascular migration, we propose that chemotactic responsiveness contributes to the ability of circulating tumor cells to localize in extravascular tissues. This study was done to seek a relationship between chemotactic responsiveness of tumor cells and their behavior in vivo. Two subpopulations of cells were isolated from a methylcholanthrene-induced fibrosarcoma. The two cell lines were compared with regard to their biologic behavior in vivo and their chemotactic responsiveness in vitro. In vivo one subpopulation was highly malignant. An injection of 2.0 x 10(5) cells into the footpad of syngeneic mice led to the development of primary tumors in 87% of the animals and lung metastases in 61% of the animals with primary tumors. This line demonstrated chemotaxis to a factor that behaved similarly in gel filtration and showed immunologic reactivity similar to that of a previously described tumor cell chemotactic factor derived from the fifth component of complement. In contrast, an injection of the same number of cells from the second subpopulation of fibrosarcoma cells led to the development of primary tumors in only 12% of syngeneic mice, and lung metastases did not occur. Neither this subpopulation nor normal embryonic fibroblasts demonstrated chemotactic responsiveness. We postulate that the ability of tumor cells to respond to specific chemotactic stimuli may be one of the many unique properties which distinguish malignant from benign tumor cells. This is the first report documenting the chemotactic responsiveness of non-ascites tumors and fibrosarcomas. PMID:7468766

  15. Angiogenic, mitogenic, and chemotactic activity in human follicular fluid (HFF)

    SciTech Connect

    Bryant, S.M.; Frederick, J.L.; Gale, J.A.; Campeau, J.D.; diZerega, G.S.

    1986-03-01

    The capacity of human follicular fluid to induce neovascularization was investigated. Three parameters were employed to assess the extent of angiogenic activity: (1) new vessel formation on the chick chorioallantoic membrane (CAM); (2) mitogenesis and (3) chemotaxis of bovine aortic endothelial cells. HFF resuspended in hydron induced new blood vessel formation on the CAM, as manifested by a spoke-wheel pattern of vessels radiating from the locus of application after two to six days. Endothelial cells cultured with a 1:10 dilution of HFF for two days demonstrated an enhanced incorporation of /sup 3/H-thymidine into acid-precipitable material when compared to control cells. The ratio of counts-per-minute for HFF stimulated cells versus control cells was 3.02 +/- 0.53 (anti S.E.M., n = 5). Endothelial cells also exhibited a directional migration towards HFF through a polycarbonate membrane with 8..mu..m pores. The ratio of the number of cells migrating completely through the filter towards a 1:10 dilution of HFF compared to those migrating towards medium alone was 5.61 +/- 0.61 (anti +/- S.E.M., n = 3). Human serum at an equivalent protein concentration as HFF demonstrated no activity in the CAM, mitogenic, and chemotaxis assays. These results demonstrate specific angiogenic, mitogenic and chemotactic activity in human follicular fluid.

  16. Speed-dependent chemotactic precision in marine bacteria.

    PubMed

    Son, Kwangmin; Menolascina, Filippo; Stocker, Roman

    2016-08-01

    Chemotaxis underpins important ecological processes in marine bacteria, from the association with primary producers to the colonization of particles and hosts. Marine bacteria often swim with a single flagellum at high speeds, alternating "runs" with either 180° reversals or ∼90° "flicks," the latter resulting from a buckling instability of the flagellum. These adaptations diverge from Escherichia coli's classic run-and-tumble motility, yet how they relate to the strong and rapid chemotaxis characteristic of marine bacteria has remained unknown. We investigated the relationship between swimming speed, run-reverse-flick motility, and high-performance chemotaxis by tracking thousands of Vibrio alginolyticus cells in microfluidic gradients. At odds with current chemotaxis models, we found that chemotactic precision-the strength of accumulation of cells at the peak of a gradient-is swimming-speed dependent in V. alginolyticus Faster cells accumulate twofold more tightly by chemotaxis compared with slower cells, attaining an advantage in the exploitation of a resource additional to that of faster gradient climbing. Trajectory analysis and an agent-based mathematical model revealed that this unexpected advantage originates from a speed dependence of reorientation frequency and flicking, which were higher for faster cells, and was compounded by chemokinesis, an increase in speed with resource concentration. The absence of any one of these adaptations led to a 65-70% reduction in the population-level resource exposure. These findings indicate that, contrary to what occurs in E. coli, swimming speed can be a fundamental determinant of the gradient-seeking capabilities of marine bacteria, and suggest a new model of bacterial chemotaxis. PMID:27439872

  17. Bacteroidales ectosymbionts of gut flagellates shape the nitrogen-fixing community in dry-wood termites.

    PubMed

    Desai, Mahesh S; Brune, Andreas

    2012-07-01

    Although it is well documented that the lack of nitrogen in the diet of wood-feeding termites is compensated by the nitrogen-fixing capacity of their gut microbiota, the bacteria responsible for this activity are largely unknown. Here, we analyzed the diversity and expression of nitrogenase genes (homologs of nifH) in four species of dry-wood termites (Kalotermitidae), which thrive on a particularly nitrogen-poor resource. Although each species harbored a highly diverse suite of termite-specific homologs in their microliter-sized hindgut, only a core set related to nifH genes of Treponema and Azoarcus spp., 'Azobacteroides pseudotrichonymphae', the first member of the Bacteroidales identified as a diazotroph, and termite-gut-specific anfH genes of hitherto unknown origin were preferentially expressed. Transcription patterns corroborated that the populations of active diazotrophs differ fundamentally between termite genera. Capillary-picked suspensions of the flagellates Devescovina arta and Snyderella tabogae revealed that their bacterial ectosymbionts each possess two paralogs of nifH, which apparently have been acquired consecutively during evolution of Bacteroidales, but only one of them (anfH) is actively expressed. Transcription patterns correlated neither with the molybdenum content of the diet nor with intestinal hydrogen concentrations, measured with microsensors. We propose that the nitrogen-fixing community in different dry-wood termites is shaped by the symbionts of their specific flagellate populations. Our findings suggest that the diazotrophic nature of 'Armantifilum devescovinae' has an important role in the nitrogen metabolism of dry-wood termites and is the driving force of co-evolution with its flagellate host. PMID:22189498

  18. Bacteroidales ectosymbionts of gut flagellates shape the nitrogen-fixing community in dry-wood termites

    PubMed Central

    Desai, Mahesh S; Brune, Andreas

    2012-01-01

    Although it is well documented that the lack of nitrogen in the diet of wood-feeding termites is compensated by the nitrogen-fixing capacity of their gut microbiota, the bacteria responsible for this activity are largely unknown. Here, we analyzed the diversity and expression of nitrogenase genes (homologs of nifH) in four species of dry-wood termites (Kalotermitidae), which thrive on a particularly nitrogen-poor resource. Although each species harbored a highly diverse suite of termite-specific homologs in their microliter-sized hindgut, only a core set related to nifH genes of Treponema and Azoarcus spp., ‘Azobacteroides pseudotrichonymphae', the first member of the Bacteroidales identified as a diazotroph, and termite-gut-specific anfH genes of hitherto unknown origin were preferentially expressed. Transcription patterns corroborated that the populations of active diazotrophs differ fundamentally between termite genera. Capillary-picked suspensions of the flagellates Devescovina arta and Snyderella tabogae revealed that their bacterial ectosymbionts each possess two paralogs of nifH, which apparently have been acquired consecutively during evolution of Bacteroidales, but only one of them (anfH) is actively expressed. Transcription patterns correlated neither with the molybdenum content of the diet nor with intestinal hydrogen concentrations, measured with microsensors. We propose that the nitrogen-fixing community in different dry-wood termites is shaped by the symbionts of their specific flagellate populations. Our findings suggest that the diazotrophic nature of ‘Armantifilum devescovinae' has an important role in the nitrogen metabolism of dry-wood termites and is the driving force of co-evolution with its flagellate host. PMID:22189498

  19. Position-dependent chemotactic response of slowly migrating cells in sigmoidal concentration profiles

    NASA Astrophysics Data System (ADS)

    Renner, A.; Jaeger, M. S.; Lankenau, A.; Duschl, C.

    2013-09-01

    Characterizing the chemotactic motility of slowly migrating cells as a function of time is still challenging. In this paper, we use a microfluidic device for investigating the chemotactic activity of HFF-1 fibroblasts in a sigmoidal concentration profile of epidermal growth factor (EGF). Sigmoidal concentration profiles are very common in biological systems but, in contrast to linear gradients, are much less studied in microfluidic systems. We monitored cell migration for up to 10 hours and found that chemotaxis is strongest where the absolute EGF concentration is below 25 pM ( K D of EGF is 1 nM). Calculating the fraction of receptor occupancy ( FRO) at the front and rear of the cells showed that the chemotactic activity of HFF-1 cells scaled with the difference in FRO between both ends of the cell normalized by the average FRO av of the cell. Interestingly, the mean chemotactic index of the cells was found to be a function of the gradient at the starting position and did not change when cells were entering into other regions of the highly non-linear concentration profile. Our studies demonstrate the usefulness of stable sigmoidal concentration profiles produced in microfluidic channels for a detailed analysis of the chemotactic response of slowly migrating cells.

  20. Enhanced Retention of Chemotactic Bacteria in a Pore Network with Residual NAPL Contamination.

    PubMed

    Wang, Xiaopu; Lanning, Larry M; Ford, Roseanne M

    2016-01-01

    Nonaqueous-phase liquid (NAPL) contaminants are difficult to eliminate from natural aquifers due, in part, to the heterogeneous structure of the soil. Chemotaxis enhances the mixing of bacteria with contaminant sources in low-permeability regions, which may not be readily accessible by advection and dispersion alone. A microfluidic device was designed to mimic heterogeneous features of a contaminated groundwater aquifer. NAPL droplets (toluene) were trapped within a fine pore network, and bacteria were injected through a highly conductive adjacent macrochannel. Chemotactic bacteria (Pseudomonas putida F1) exhibited greater accumulation near the pore network at 0.5 m/day than both the nonchemotactic control and the chemotactic bacteria at a higher groundwater velocity of 5 m/day. Chemotactic bacteria accumulated in the vicinity of NAPL droplets, and the accumulation was 15% greater than a nonchemotactic mutant. Indirect evidence showed that chemotactic bacteria were retained within the contaminated low-permeability region longer than nonchemotactic bacteria at 0.25 m/day. This retention was diminished at 5 m/day. Numerical solutions of the bacterial-transport equations were consistent with the experimental results. Because toluene is degraded by P. putida F1, the accumulation of chemotactic bacteria around NAPL sources is expected to increase contaminant consumption and improve the efficiency of bioremediation. PMID:26633578

  1. The stability of a homogeneous suspension of chemotactic bacteria

    NASA Astrophysics Data System (ADS)

    Subramanian, G.; Koch, Donald L.; Fitzgibbon, Sean R.

    2011-04-01

    The linear stability of a homogeneous dilute suspension of chemotactic bacteria in a constant chemoattractant gradient is analyzed. The bacteria execute a run-and-tumble motion, typified by the species E. coli, wherein periods of smooth swimming (runs) are interrupted by abrupt uncorrelated changes in swimming direction (tumbles). Bacteria tumble less frequently when swimming toward regions of higher chemoattractant concentration, leading to a mean bacterial orientation and velocity in the base state. The stability of an unbounded suspension, both with and without a chemoattractant, is controlled by coupled long wavelength perturbations of the fluid velocity and bacterial orientation fields. In the former case, the most unstable perturbations have their wave vector oriented along the chemoattractant gradient. Chemotaxis reduces the critical bacteria concentration, for the onset of collective swimming, compared with that predicted by Subramanian and Koch ["Critical bacterial concentration for the onset of collective swimming," J. Fluid Mech. 632, 359 (2009)] in the absence of a chemoattractant. A part of this decrease may be attributed to the increase in the mean tumbling time in the presence of a chemoattractant gradient. A second destabilizing influence comes from the ability of the shearing motion, associated with a velocity perturbation in which the velocity and chemical gradients are aligned, to sweep prealigned bacteria into the local extensional quadrant thereby creating a stronger destabilizing active stress than in an initially isotropic suspension. The chemoattractant gradient also fundamentally alters the unstable spectrum for any finite wavenumber. In suspensions of bacteria that do not tumble, Saintillan and Shelley ["Instabilities and pattern formation in active particle suspensions: Kinetic theory and continuum simulations," Phys. Rev. Lett. 100, 178103 (2008); "Instabilities, pattern formation and mixing in active suspensions," Phys. Fluids 20

  2. Ethidium bromide: a fast fluorescent staining procedure for the detection of symbiotic partnership of flagellates and prokaryotes.

    PubMed

    Fröhlich, J; König, H

    1999-03-01

    The hindgut of 'lower' termites harbors a dense population of flagellates and bacteria. The flagellates possess ecto- and endosymbiotic prokaryotes. Most of them are hardly visible in the phase contrast microscope. Staining with the DNA-intercalating agent ethidium bromide visualizes the nuclei of the flagellates as well as the ecto- and endosymbiotic bacteria as red objects. Furthermore, it is possible to distinguish between endosymbiotic methanogens and other bacteria. Following UV excitation, the blue-green autofluorescence of the methanogenic bacteria eclipses the red fluorescence light of the intercalated ethidium bromide. The dye facilitates the observation of symbiotic bacteria and helps identify the number, shape, localization, and dividing status of the nuclei. Thus, it is a powerful tool for the examination of microorganisms in complex habitats, which are rich in strongly autofluorescent material, like wood. PMID:10192044

  3. Chemotactic and diffusive migration on a nonuniformly growing domain: numerical algorithm development and applications

    NASA Astrophysics Data System (ADS)

    Simpson, Matthew J.; Landman, Kerry A.; Newgreen, Donald F.

    2006-08-01

    A numerical algorithm to simulate chemotactic and/or diffusive migration on a one-dimensional growing domain is developed. The domain growth can be spatially nonuniform and the growth-derived advection term must be discretised. The hyperbolic terms in the conservation equations associated with chemotactic migration and domain growth are accurately discretised using an explicit central scheme. Generality of the algorithm is maintained using an operator split technique to simulate diffusive migration implicitly. The resulting algorithm is applicable for any combination of diffusive and/or chemotactic migration on a growing domain with a general growth-induced velocity field. The accuracy of the algorithm is demonstrated by testing the results against some simple analytical solutions and in an inter-code comparison. The new algorithm demonstrates that the form of nonuniform growth plays a critical role in determining whether a population of migratory cells is able to overcome the domain growth and fully colonise the domain.

  4. Chemotactic Preferences and Strain Variation in the Response of Phytophthora sojae Zoospores to Host Isoflavones

    PubMed Central

    Tyler, B. M.; Wu, M.; Wang, J.; Cheung, W.; Morris, P. F.

    1996-01-01

    The zoospores of Phytophthora sojae are chemotactically attracted to the isoflavones genistein and daidzein that are released by soybean roots. In this study we have examined the response of P. sojae zoospores to a wide range of compounds having some structural similarity to genistein and daidzein, including isoflavones, flavones, chalcones, stilbenes, benzoins, benzoates, benzophenones, acetophenones, and coumarins. Of 59 compounds examined, 43 elicited some response. A comparison of the chemotactic responses elicited by the various compounds revealed a primary role for the phenolic 4(prm1)- and 7-hydroxyl groups on the isoflavone structure. A few compounds acted as repellents, notably methylated flavones with a hydrophobic B ring. The chemotactic response to many of the analogs was markedly different among different strains of P. sojae. PMID:16535375

  5. Novel neutrophil chemotactic factor derived from human peripheral blood mononuclear leucocytes.

    PubMed Central

    Kownatzki, E; Kapp, A; Uhrich, S

    1986-01-01

    Human mononuclear leucocytes isolated from the peripheral blood by centrifugation on Ficoll-Hypaque cushions and adherent on plastic petri dishes, produced a chemotactic factor that attracted human neutrophilic granulocytes to the same extent as did optimal concentrations of the complement split product C5a and the leukotriene B4. The active component eluted from a Sephadex G-50 gel filtration column as a single peak with an apparent molecular weight of 10,000. The chemotactic activity was resistant to reductive cleavage of disulfide bonds and heating at 100 degrees C for 30 min but was lost when reduction and heating were combined. Digestion with a proteolytic enzyme eliminated the attractive potential. The data suggest that this is a novel chemotactic peptide. It is conceivable that it has been seen previously and was mistaken for a lymphokine or interleukin 1. PMID:3731527

  6. Identification of human complement factor H as a chemotactic protein for monocytes.

    PubMed Central

    Nabil, K; Rihn, B; Jaurand, M C; Vignaud, J M; Ripoche, J; Martinet, Y; Martinet, N

    1997-01-01

    We used chromatographic separation to purify to homogeneity a monomeric monocyte chemotactic protein of 150 kDa contained in mesothelioma pleural effusions. It was identified by N-terminal amino acid sequencing and immunoblotting as complement factor H, an inhibitor of the alternative complement pathway. Specific antibodies against factor H inhibited the monocyte chemotactic activity of the purified protein, which was most active at 10 nM. Factor H is a restrictive factor of alternative complement pathway activation. The new chemotactic function assigned to factor H in recruiting monocytes to the mesothelioma site might contribute to malignant cell phagocytosis via the iC3b/complement receptor type 3 pathway. These functions link the humoral and cellular immune systems. PMID:9291108

  7. Toxicity assessment of a common laundry detergent using the freshwater flagellate Euglena gracilis.

    PubMed

    Azizullah, Azizullah; Richter, Peter; Häder, Donat-Peter

    2011-09-01

    Synthetic detergents are among the commonly used chemicals in everyday life. Detergents, reaching aquatic environments through domestic and municipal wastewater, can cause many different effects in aquatic organisms. The present study was aimed at the toxicity evaluation of a commonly used laundry detergent, Ariel, using the freshwater flagellate Euglena gracilis as a biotest organism. Different parameters of the flagellate like motility, swimming velocity, cell shape, gravitactic orientation, photosynthesis and concentration of light harvesting pigments were used as end points for the toxicity assessment. No Observed Effect Concentration (NOEC) and EC(50) values were calculated for the end point parameters at four different incubation times, i.e. 0, 6, 24 and 72 h. After 72 h incubation, swimming velocity of the cells was found to be the most sensitive parameter giving NOEC and EC(50) values of 10.8 and 34 mg L(-1), respectively. After 72 h exposure to the detergent, chlorophyll a and total carotenoids were significantly decreased in cultures treated with Ariel at concentrations of 50 mg L(-1) and above while chlorophyll b significantly decreased at concentrations above 750 mg L(-1). The maximum inhibitory effect on the quantum yield of photosystem II was observed after 24 h exposure and thereafter a recovery trend was observed. Motility, gravitaxis and cell shape were strongly impaired immediately upon exposure to the detergent, but with increasing exposure time these parameters showed acclimatization to the stress and thus the NOEC values obtained after 72 h were higher than those immediately after exposure. PMID:21601907

  8. Differential freshwater flagellate community response to bacterial food quality with a focus on Limnohabitans bacteria

    PubMed Central

    Šimek, Karel; Kasalický, Vojtěch; Jezbera, Jan; Horňák, Karel; Nedoma, Jiří; Hahn, Martin W; Bass, David; Jost, Steffen; Boenigk, Jens

    2013-01-01

    Different bacterial strains can have different value as food for heterotrophic nanoflagellates (HNF), thus modulating HNF growth and community composition. We examined the influence of prey food quality using four Limnohabitans strains, one Polynucleobacter strain and one freshwater actinobacterial strain on growth (growth rate, length of lag phase and growth efficiency) and community composition of a natural HNF community from a freshwater reservoir. Pyrosequencing of eukaryotic small subunit rRNA amplicons was used to assess time-course changes in HNF community composition. All four Limnohabitans strains and the Polynucleobacter strain yielded significant HNF community growth while the actinobacterial strain did not although it was detected in HNF food vacuoles. Notably, even within the Limnohabitans strains we found significant prey-related differences in HNF growth parameters, which could not be related only to size of the bacterial prey. Sequence data characterizing the HNF communities showed also that different bacterial prey items induced highly significant differences in community composition of flagellates. Generally, Stramenopiles dominated the communities and phylotypes closely related to Pedospumella (Chrysophyceae) were most abundant bacterivorous flagellates rapidly reacting to addition of the bacterial prey of high food quality. PMID:23552621

  9. Genetic evidence for a mitochondriate ancestry in the 'amitochondriate' flagellate Trimastix pyriformis.

    PubMed

    Hampl, Vladimir; Silberman, Jeffrey D; Stechmann, Alexandra; Diaz-Triviño, Sara; Johnson, Patricia J; Roger, Andrew J

    2008-01-01

    Most modern eukaryotes diverged from a common ancestor that contained the alpha-proteobacterial endosymbiont that gave rise to mitochondria. The 'amitochondriate' anaerobic protist parasites that have been studied to date, such as Giardia and Trichomonas harbor mitochondrion-related organelles, such as mitosomes or hydrogenosomes. Yet there is one remaining group of mitochondrion-lacking flagellates known as the Preaxostyla that could represent a primitive 'pre-mitochondrial' lineage of eukaryotes. To test this hypothesis, we conducted an expressed sequence tag (EST) survey on the preaxostylid flagellate Trimastix pyriformis, a poorly-studied free-living anaerobe. Among the ESTs we detected 19 proteins that, in other eukaryotes, typically function in mitochondria, hydrogenosomes or mitosomes, 12 of which are found exclusively within these organelles. Interestingly, one of the proteins, aconitase, functions in the tricarboxylic acid cycle typical of aerobic mitochondria, whereas others, such as pyruvate:ferredoxin oxidoreductase and [FeFe] hydrogenase, are characteristic of anaerobic hydrogenosomes. Since Trimastix retains genetic evidence of a mitochondriate ancestry, we can now say definitively that all known living eukaryote lineages descend from a common ancestor that had mitochondria. PMID:18167542

  10. Combined effects of the herbicide terbuthylazine and temperature on different flagellates from the Northern Adriatic Sea.

    PubMed

    Fiori, Emanuela; Mazzotti, Matilde; Guerrini, Franca; Pistocchi, Rossella

    2013-03-15

    The triazinic herbicide terbuthylazine (TBA) is becoming an emergent contaminant in Italian rivers and in coastal and groundwater. A preliminary analysis of the sensitivity of marine flagellates to TBA was performed by monitoring the photosynthetic efficiency of nine species (belonging to the Dinophyceae or Raphidophyceae class) isolated from the Adriatic Sea. Different sensitivity levels for each flagellate were observed and the most sensitive microalgae, based on PSII inhibition, were: Gonyaulax spinifera>Fibrocapsa japonica>Lingulodinium polyedrum while the most resistant were two species belonging to the Prorocentrum genus. Then the response of two microalgae to drivers, such as temperature and terbuthylazine, applied in combination was also investigated. Two potentially toxic flagellates, Prorocentrum minimum and G. spinifera, were exposed, under different temperature conditions (15, 20 and 25°C), to TBA concentrations that did not completely affect PSII. For both flagellates, effects of TBA on algal growth, measured through cell density and carbon analysis, as well as on the photosynthetic activity are reported. All parameters analyzed showed a negative effect of TBA from the exponential phase. TBA effect on algal growth was significantly enhanced at the optimal temperature conditions (20 and 25°C), while no difference between control and herbicide treatments were detected for G. spinifera grown at 15°C, which represented a stress condition for this species. The maximum inhibition of photosynthetic efficiency was found at 20°C for both organisms. Both flagellates increased cell carbon and nitrogen content in herbicide treatments compared to the control, except G. spinifera grown at 15°C. Chlorophyll-a production was increased only in G. spinifera exposed to 5 μg L(-1) of TBA and the effect was enhanced with the increase of temperature. Herbicide-induced variations in cellular components determined changes in cellular carbon:nitrogen (C:N) and

  11. Bleomycin-induced flagellate erythema in a patient with Hodgkin's lymphoma - A case report and review of literature.

    PubMed

    Vennepureddy, A; Siddique, M N; Odaimi, M; Terjanian, T

    2016-06-01

    Bleomycin is a glycopeptide used as a chemotherapeutic agent for lymphomas, germ cell tumors, and pleurodesis of malignant pleural effusions. The pulmonary toxicity of bleomycin is well known while the cutaneous side effects are uncommon and varies from generalized hyperpigmentation, sclerodermoid changes, erythema multiformae, and gangrene to flagellate dermatosis. Here we report a characteristic but rare side effect of flagellate erythema, which developed secondary to bleomycin in a 27-year old woman with Hodgkin's lymphoma after two cycles of treatment with adriamycin, bleomycin, vinblastine, dacarbazine regimen. The rash subsided after discontinuation of bleomycin and treatment with steroids. PMID:25855241

  12. Attachment of human C5a des Arg to its cochemotaxin is required for maximum expression of chemotactic activity.

    PubMed Central

    Perez, H D; Chenoweth, D E; Goldstein, I M

    1986-01-01

    The chemotactic activity of human C5a des Arg is enhanced significantly by an anionic polypeptide (cochemotaxin) in normal human serum and plasma. We have found that the cochemotaxin attaches to the oligosaccharide chain of native C5a des Arg to form a complex with potent chemotactic activity for human polymorphonuclear leukocytes. Although capable of enhancing the chemotactic activity of native C5a des Arg, the cochemotaxin had no effect on the chemotactic activity of either deglycosylated C5a des Arg, native C5a, or N-formyl-methionyl-leucyl-phenylalanine. Of the known components of the oligosaccharide chain, only sialic acid prevented enhancement by the cochemotaxin of the chemotactic activity exhibited by native C5a des Arg. Sialic acid also prevented the formation of C5a des Arg-cochemotaxin complexes, detected by acid polyacrylamide gel electrophoresis, molecular sieve chromatography on polyacrylamide gels, and sucrose density gradient ultracentrifugation. Images PMID:3782473

  13. The Bacterivorous Soil Flagellate Heteromita globosa Reduces Bacterial Clogging under Denitrifying Conditions in Sand-Filled Aquifer Columns

    PubMed Central

    Mattison, Richard G.; Taki, Hironori; Harayama, Shigeaki

    2002-01-01

    An exopolymer (slime)-producing soil bacterium Pseudomonas sp. (strain PS+) rapidly clogged sand-filled columns supplied with air-saturated artificial groundwater containing glucose (500 mg liter−1) as a sole carbon source and nitrate (300 mg liter−1) as an alternative electron acceptor. After 80 days of operation under denitrifying conditions, the effective porosity and saturated hydraulic conductivity (permeability) of sand in these columns had fallen by 2.5- and 26-fold, respectively. Bacterial biofilms appeared to induce clogging by occluding pore spaces with secreted exopolymer, although there may also have been a contribution from biogas generated during denitrification. The bacterivorous soil flagellate Heteromita globosa minimized reductions in effective porosity (1.6-fold) and permeability (13-fold), presumably due to grazing control of biofilms. Grazing may have limited growth of bacterial biomass and hence the rate of exopolymer and biogas secretion into pore spaces. Evidence for reduction in biogas production is suggested by increased nitrite efflux from columns containing flagellates, without a concomitant increase in nitrate consumption. There was no evidence that flagellates could improve flow conditions if added once clogging had occurred (60 days). Presumably, bacterial biofilms and their secretions were well established at that time. Nevertheless, this study provides evidence that bacterivorous flagellates may play a positive role in maintaining permeability in aquifers undergoing remediation treatments. PMID:12200311

  14. Phylogenetic Position and Molecular Chronology of a Colonial Green Flagellate, Stephanosphaera pluvialis (Volvocales, Chlorophyceae), among Unicellular Algae.

    PubMed

    Munakata, Hidehito; Nakada, Takashi; Nakahigashi, Kenji; Nozaki, Hisayoshi; Tomita, Masaru

    2016-05-01

    The genus Balticola comprises a group of unicellular green flagellate algae and is composed of four species formerly classified in the genus Haematococcus. Balticola is closely related to a colonial green flagellate, Stephanosphaera pluvialis. Although the phylogeny among these genera was previously investigated based on two nuclear gene sequences, the phylogenetic sister of S. pluvialis has yet to be determined. In the present study, the species diversity of Balticola and Stephanosphaera was investigated using 18S rRNA gene sequences, and phylogenetic analyses of combined nuclear and chloroplast gene sequences were performed to understand the evolutionary origin of coloniality in Stephanosphaera. The divergence times of four colonial volvocalean flagellates from their respective unicellular sisters were also estimated. Six Balticola genotypes and a single Stephanosphaera genotype were recognized, and one Balticola genotype was resolved as the sister of S. pluvialis, showing that Balticola is a nonmonophyletic genus. The divergence time of Stephanosphaera from its nearest Balticola relative was estimated to be 4-63 million years ago, and these genera represent the most recently diverged pair of unicellular and colonial flagellates among the Volvocales. PMID:26595722

  15. Enhanced Retention of Chemotactic Bacteria in a Pore Network with Residual NAPL Contamination

    NASA Astrophysics Data System (ADS)

    Ford, R.; Wang, X.

    2013-12-01

    Nonaqueous phase liquid (NAPL) contaminants are difficult to eliminate from natural aquifers due, in part, to the heterogeneous structure of the soil matrix. Residual NAPL ganglia remain trapped in regions where the hydraulic conductivity is relatively low. Bioremediation processes depend on adequate mixing of microbial populations and the groundwater contaminants that they degrade. The ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, known as chemotaxis, can enhance the mixing of bacteria with contaminant sources that may not be readily accessible by advection and dispersion alone. The impact of chemotaxis on bacterial abundance within a low conductivity NAPL-contaminated region of a well-characterized porous matrix was investigated. A microfluidic device was designed to mimic heterogeneous features of a contaminated groundwater system. NAPL ganglia (toluene) were trapped within a fine pore network, and bacteria were injected into the system through a highly conductive adjacent channel. Chemotactic bacteria (P. putida F1) migrated preferentially towards and accumulated in the vicinity of NAPL contaminant sources. The accumulation of chemotactic bacteria was 15% greater in comparison to a nonchemotactic mutant (P. putida F1 CheA). Bacteria in the microfluidic device were subjected to different flow velocities from 0.25 to 5 m/d encompassing the range of typical groundwater flow rates. Chemotactic bacteria exhibited greater accumulation near the intersection between the macrochannel and the porous network at a flow velocity of 0.5 m/d than both the nonchemotactic mutant control and the chemotactic bacteria at a higher flow velocity of 5 m/d. Breakthrough curves observed at the outlet provided indirect evidence that chemotactic bacteria were retained within the contaminated low permeable region for a longer time than the nonchemotactic bacteria at a flow velocity of 0.25 m/d. This retention was

  16. Invasive Bombus terrestris (Hymenoptera: Apidae) parasitized by a flagellate (Euglenozoa: Kinetoplastea) and a neogregarine (Apicomplexa: Neogregarinorida).

    PubMed

    Plischuk, Santiago; Lange, Carlos E

    2009-11-01

    The flagellate Crithidia bombi and the neogregarine Apicystis bombi have been found in individuals of Bombus terrestris, a Palaearctic species of bumble bee commercially reared and shipped worldwide for pollination services. B. terrestris has recently entered into the northwestern Patagonia region of Argentina from Chile, where it was introduced in 1998. Prevalence was 21.6% for C. bombi and 3.6% for A. bombi (n=111). The pathogens were not detected in 441 bumble bees belonging to five of the eight known Argentine native species (Bombus atratus, Bombus morio, Bombus bellicosus, Bombus opifex, Bombus tucumanus) collected elsewhere in the country. Although the absence of natural occurrence of C. bombi and A. bombi in Argentine native bumble bees cannot be ascertained at present due to the limited surveys performed, it is important to report their detection in invasive B. terrestris. The invasion event is relatively recent and the accompanying pathogens are not species specific within the genus Bombus. PMID:19682459

  17. Induction of neutrophil chemotactic factor production by staurosporine in rat peritoneal neutrophils

    PubMed Central

    Edamatsu, Takeo; Xiao, Yi-Qun; Tanabe, Jun-ichi; Mue, Suetsugu; Ohuchi, Kazuo

    1997-01-01

    Incubation of rat peritoneal neutrophils in medium containing various concentrations of staurosporine (6.4–64 nM) increased the neutrophil chemotactic activity in the conditioned medium in a time- and concentration-dependent manner. Separation of the neutrophil chemotactic activity in the conditioned medium by isoelectric focusing revealed that staurosporine (64 nM) stimulated the production of basic (pH>8) neutrophil chemotactic factors, while TPA (12-O-tetradecanoylphorbol 13-acetate, 49 nM) stimulated the production of both basic (pH>8) and acidic (pH 5) neutrophil chemotactic factors. Determination by immunoassay of cytokine-induced neutrophil chemoattractant (CINC)-1, -2α, -2β and -3 in the conditioned medium at 4 h revealed that staurosporine (64 nM) and TPA (49 nM) strongly stimulated the production of CINC-3 (staurosporine, 133.0±3.8; TPA, 26.7±1.0; control, 0.32±0.01 ng ml−1, means±s.e.mean from four samples) compared to CINC-1 (staurosporine, 55.0±1.2; TPA, 12.2±0.3; control, 0.56±0.01 ng ml−1), and CINC-2α (staurosporine, 1.09±0.03; TPA, 0.90±0.02; control, <0.10 ng ml−1). CINC-2β was below the detectable amount (<0.078 ng ml−1). The level of CINC-3 mRNA in the peritoneal neutrophils was determined by reverse transcription-polymerase chain reaction. Staurosporine (64 nM) and TPA (49 nM) enhanced the level of CINC-3 mRNA time-dependently, but had no effect on GAPDH mRNA levels. Production of staurosporine-induced neutrophil chemotactic factor was inhibited by the protein kinase C inhibitors, H-7 (IC50, 12.3 μM), calphostin C (IC50, 0.77 μM) and Ro 31-8425 (24.3% inhibition at 10 μM), and by the tyrosine kinase inhibitor, genistein (IC50, 68.5 μM). Production of TPA-induced neutrophil chemotactic factor was also inhibited by both inhibitors. Both the staurosporine- and the TPA-induced increase in CINC-3 mRNA levels were suppressed by H-7 and genistein. PMID:9283699

  18. Dynamic chemotactic response of fibroblasts to local stimulation using EGF-immobilized microbeads.

    PubMed

    Aratsu, Fumihiro; Harada, Ichiro; Yoshimura, Soichiro; Cho, Chong-Su; Akaike, Toshihiro; Tagawa, Yoh-ichi

    2014-03-01

    Directional cellular migrations as a chemotactic response to spatially inhomogeneous growth factor stimulation play an important role in establishing physiological mechanisms and pathological events in cells. We developed epidermal growth factor (EGF)-immobilized microbeads by photoreaction and evaluated its local stimulatory effects on the dynamic chemotactic motility of fibroblasts. The local stimulation resulted in global activation of ERK 1/2 and directionality of cellular migration. The cellular migration by stimulation using 3-μm diameter EGF-immobilized microbeads persisted for a longer time, were involved a wider field and their number were further increased with stimulation. This effective technique allows cellular migration and biochemical analyses that will help elucidate the mechanisms involved in signal transduction by spatially inhomogeneous stimulation of the growth factor. PMID:24373421

  19. Fucose-binding Lotus tetragonolobus lectin binds to human polymorphonuclear leukocytes and induces a chemotactic response.

    PubMed

    VanEpps, D E; Tung, K S

    1977-09-01

    Fucose-binding L. tetragonolobus lectin to the surface of human polymorphonuclear leukocytes (PMN) and induces a chemotactic response. Both surface binding and chemotaxis are inhibited by free fucose but not by fructose, mannose, or galactose. The lectin-binding sites on PMN are unrelated to the A, B, or O blood group antigen. Utilization of this lectin should be a useful tool in isolating PMN membrane components and in analyzing the mechanism of neutrophil chemotaxis. PMID:330752

  20. Automated Chemotactic Sorting and Single-cell Cultivation of Microbes using Droplet Microfluidics

    PubMed Central

    Dong, Libing; Chen, Dong-Wei; Liu, Shuang-Jiang; Du, Wenbin

    2016-01-01

    We report a microfluidic device for automated sorting and cultivation of chemotactic microbes from pure cultures or mixtures. The device consists of two parts: in the first part, a concentration gradient of the chemoeffector was built across the channel for inducing chemotaxis of motile cells; in the second part, chemotactic cells from the sample were separated, and mixed with culture media to form nanoliter droplets for encapsulation, cultivation, enumeration, and recovery of single cells. Chemotactic responses were assessed by imaging and statistical analysis of droplets based on Poisson distribution. An automated procedure was developed for rapid enumeration of droplets with cell growth, following with scale-up cultivation on agar plates. The performance of the device was evaluated by the chemotaxis assays of Escherichia coli (E. coli) RP437 and E. coli RP1616. Moreover, enrichment and isolation of non-labelled Comamonas testosteroni CNB-1 from its 1:10 mixture with E. coli RP437 was demonstrated. The enrichment factor reached 36.7 for CNB-1, based on its distinctive chemotaxis toward 4-hydroxybenzoic acid. We believe that this device can be widely used in chemotaxis studies without necessarily relying on fluorescent labelling, and isolation of functional microbial species from various environments. PMID:27074762

  1. Alveolar macrophage-derived chemotactic factor: kinetics of in vitro production and partial characterization.

    PubMed Central

    Merrill, W W; Naegel, G P; Matthay, R A; Reynolds, H Y

    1980-01-01

    Alveolar macrophages are the initial phagocytic cells that encounter foreign material and particulates deposited in the terminal airways. We have examined a mechanism by which these cells, after phagocytic challenge, may control or amplify the inflammatory response in lung parenchyma. Normal human alveolar macrophages (AM) were studied from eight subjects. With in vitro culture, AM produced and released two substances into culture media which have potent chemoattractant activity for blood polymorphonuclear granulocytes (PMN) and negligible activity for mononuclear cells. Release of these factors is maximally stimulated by aggregated human immunoglobulin (Ig)G or zymosan particles; however, simple adhesion of the macrophages to plastic surfaces is also sufficient to stimulate release of these chemotactic substances. The larger substance (10,000 daltons) is immunologically distinct from C5a and interacts with a different PMN membrane receptor than that known to exist for formyl-methionyl-leucyl-phenylalanine. Its chemotactic activity is sensitive to the enzymatic effect of trypsin. Although producing a single elution peak on gelfiltration chromatography, electrofocusing in polyacrylamide gels yielded five peaks of radioactivity. Chemotactic activity was localized to a fraction with a pI = 5.0. The smaller molecular weight substance has been less well characterized. Thus, the human AM can produce at least two factors which attract PMN and this capability may augment the local inflammatory response in the lung. PMID:7356678

  2. Automated Chemotactic Sorting and Single-cell Cultivation of Microbes using Droplet Microfluidics

    NASA Astrophysics Data System (ADS)

    Dong, Libing; Chen, Dong-Wei; Liu, Shuang-Jiang; Du, Wenbin

    2016-04-01

    We report a microfluidic device for automated sorting and cultivation of chemotactic microbes from pure cultures or mixtures. The device consists of two parts: in the first part, a concentration gradient of the chemoeffector was built across the channel for inducing chemotaxis of motile cells; in the second part, chemotactic cells from the sample were separated, and mixed with culture media to form nanoliter droplets for encapsulation, cultivation, enumeration, and recovery of single cells. Chemotactic responses were assessed by imaging and statistical analysis of droplets based on Poisson distribution. An automated procedure was developed for rapid enumeration of droplets with cell growth, following with scale-up cultivation on agar plates. The performance of the device was evaluated by the chemotaxis assays of Escherichia coli (E. coli) RP437 and E. coli RP1616. Moreover, enrichment and isolation of non-labelled Comamonas testosteroni CNB-1 from its 1:10 mixture with E. coli RP437 was demonstrated. The enrichment factor reached 36.7 for CNB-1, based on its distinctive chemotaxis toward 4-hydroxybenzoic acid. We believe that this device can be widely used in chemotaxis studies without necessarily relying on fluorescent labelling, and isolation of functional microbial species from various environments.

  3. Composition of heterotrophic flagellates in coastal waters of different trophic status.

    PubMed

    Cheung, Man Kit; Nong, Wenyan; Kwan, Hoi Shan; Wong, Chong Kim

    2013-09-01

    Heterotrophic flagellates (HFs) are important members of the aquatic microbial food web. However, information on their spatial patterns in relation to eutrophication is limited. Here, we examined the composition and spatial distributions of HFs (<3 μm) in subtropical coastal waters of different trophic status by re-analyzing two previously published small subunit rDNA pyrosequence datasets using information from the newly launched Protist Ribosomal Reference database (PR(2)). Whereas the contributions of different major clades composing the Marine Stramenopiles (MASTs), picobiliphytes and Chrysophyceae were found relatively comparable between the stations, contrasting compositions of the Marine Alveolates (MALV) groups I and II were observed. The high and relatively stable contribution of MAST-1, -3 and -7 among the MASTs in both stations suggest their importance as bacterial grazers in coastal waters, irrespective of trophic status. By contrast, the dominance of clades 3, 5 and 14 of MALV II in the eutrophic station implies their importance in regulating the dinoflagellate population at the site. Our study provides insights into the ecological importance of different HF groups in eutrophic coastal ecosystems. PMID:23636495

  4. Transient Superdiffusion and Long-Range Correlations in the Motility Patterns of Trypanosomatid Flagellate Protozoa

    PubMed Central

    Alves, Luiz G. A.; Scariot, Débora B.; Guimarães, Renato R.; Nakamura, Celso V.; Mendes, Renio S.; Ribeiro, Haroldo V.

    2016-01-01

    We report on a diffusive analysis of the motion of flagellate protozoa species. These parasites are the etiological agents of neglected tropical diseases: leishmaniasis caused by Leishmania amazonensis and Leishmania braziliensis, African sleeping sickness caused by Trypanosoma brucei, and Chagas disease caused by Trypanosoma cruzi. By tracking the positions of these parasites and evaluating the variance related to the radial positions, we find that their motions are characterized by a short-time transient superdiffusive behavior. Also, the probability distributions of the radial positions are self-similar and can be approximated by a stretched Gaussian distribution. We further investigate the probability distributions of the radial velocities of individual trajectories. Among several candidates, we find that the generalized gamma distribution shows a good agreement with these distributions. The velocity time series have long-range correlations, displaying a strong persistent behavior (Hurst exponents close to one). The prevalence of “universal” patterns across all analyzed species indicates that similar mechanisms may be ruling the motion of these parasites, despite their differences in morphological traits. In addition, further analysis of these patterns could become a useful tool for investigating the activity of new candidate drugs against these and others neglected tropical diseases. PMID:27007779

  5. Experimental infection of chickens by a flagellated motile strain of Salmonella enterica serovar Gallinarum biovar Gallinarum.

    PubMed

    Lopes, P D; Freitas Neto, O C; Batista, D F A; Denadai, J; Alarcon, M F F; Almeida, A M; Vasconcelos, R O; Setta, A; Barrow, P A; Berchieri, A

    2016-08-01

    Salmonella enterica subsp. enterica serovar Gallinarum biovar Gallinarum (SG) causes fowl typhoid (FT), a septicaemic disease which can result in high mortality in poultry flocks. The absence of flagella in SG is thought to favour systemic invasion, since bacterial recognition via Toll-like receptor (TLR)-5 does not take place during the early stages of FT. In the present study, chicks susceptible to FT were inoculated with a wild type SG (SG) or its flagellated motile derivative (SG Fla(+)). In experiment 1, mortality and clinical signs were assessed, whereas in experiment 2, gross pathology, histopathology, systemic invasion and immune responses were evaluated. SG Fla(+) infection resulted in later development of clinical signs, lower mortality, lower bacterial numbers in the liver and spleen, and less severe pathological changes compared to SG. The CD8(+) T lymphocyte population was higher in the livers of chicks infected with SG at 4 days post-inoculation (dpi). Chicks infected with SG had increased expression of interleukin (IL)-6 mRNA in the caecal tonsil at 1 dpi and increased expression of IL-18 mRNA in the spleen at 4 dpi. In contrast, the CD4(+) T lymphocyte population was higher at 6 dpi in the livers of birds infected with SG Fla(+). Therefore, flagella appeared to modulate the chicken immune response towards a CD4(+) T profile, resulting in more efficient bacterial clearance from systemic sites and milder infection. PMID:27387725

  6. Lineage-specific activities of a multipotent mitochondrion of trypanosomatid flagellates.

    PubMed

    Škodová-Sveráková, Ingrid; Verner, Zdeněk; Skalický, Tomáš; Votýpka, Jan; Horváth, Anton; Lukeš, Julius

    2015-04-01

    Trypanosomatids are a very diverse group composed of monoxenous and dixenous parasites belonging to the excavate class Kinetoplastea. Here we studied the respiration of five monoxenous species (Blechomonas ayalai, Herpetomonas muscarum, H. samuelpessoai, Leptomonas pyrrhocoris and Sergeia podlipaevi) introduced into culture, each representing a novel yet globally distributed and/or species-rich clade, and compare them with well-studied flagellates Trypanosoma brucei, Phytomonas serpens, Crithidia fasciculata and Leishmania tarentolae. Differences in structure and activities of respiratory chain complexes, respiration and other biochemical parameters recorded under laboratory conditions reveal their substantial diversity, likely a reflection of different host environments. Phylogenetic relationships of the analysed trypanosomatids do not correlate with their biochemical parameters, with the differences within clades by far exceeding those among clades. As the S. podlipaevi canonical respiratory chain complexes have very low activities, we believe that its mitochondrion is utilised for purposes other than oxidative phosphorylation. Hence, the single reticulated mitochondrion of diverse trypanosomatids seems to retain multipotency, with the capacity to activate its individual components based on the host environment. PMID:25557487

  7. Developmental stages of Trypanosoma cruzi-like flagellates in Cavernicola pilosa.

    PubMed

    Marinkelle, C J

    1982-11-01

    The developmental stages of Trypanosoma cruzi ssp., found in the intestinal tract of Cavernicola pilosa, are described and measurements given for nine life stages. The frequencies of the various stages in foregut, midgut and hindgut of the triatomines are provided; parasites were rare in the foregut and metatrypomastigotes were seen only in the mid- and hindguts. All adult bugs examined harboured intestinal infections of T. cruzi-like flagellates, large clumps of amastigotes were frequently observed in the midgut. The faeces of C. pilosa, containing metacyclic trypomastigotes, did not produce patent parasitaemia when inoculated into mice. Inoculated mice were not protected against subsequent challenge infections with the highly virulent Tulahuen stock of T. c. cruzi. The blood of bats also failed to produce parasitaemia when inoculated into mice, nor were the mice protected against subsequent challenges with T. c. cruzi. Although the developmental stages described were very similar to those of T. c. cruzi it is presumed that they were stages of T. c. marinkellei because of their failure to infect mice and Rhodnius prolixus, and their failure to protect inoculated mice against challenge with T. c. cruzi. PMID:6820697

  8. Transient Superdiffusion and Long-Range Correlations in the Motility Patterns of Trypanosomatid Flagellate Protozoa.

    PubMed

    Alves, Luiz G A; Scariot, Débora B; Guimarães, Renato R; Nakamura, Celso V; Mendes, Renio S; Ribeiro, Haroldo V

    2016-01-01

    We report on a diffusive analysis of the motion of flagellate protozoa species. These parasites are the etiological agents of neglected tropical diseases: leishmaniasis caused by Leishmania amazonensis and Leishmania braziliensis, African sleeping sickness caused by Trypanosoma brucei, and Chagas disease caused by Trypanosoma cruzi. By tracking the positions of these parasites and evaluating the variance related to the radial positions, we find that their motions are characterized by a short-time transient superdiffusive behavior. Also, the probability distributions of the radial positions are self-similar and can be approximated by a stretched Gaussian distribution. We further investigate the probability distributions of the radial velocities of individual trajectories. Among several candidates, we find that the generalized gamma distribution shows a good agreement with these distributions. The velocity time series have long-range correlations, displaying a strong persistent behavior (Hurst exponents close to one). The prevalence of "universal" patterns across all analyzed species indicates that similar mechanisms may be ruling the motion of these parasites, despite their differences in morphological traits. In addition, further analysis of these patterns could become a useful tool for investigating the activity of new candidate drugs against these and others neglected tropical diseases. PMID:27007779

  9. Polarotaxis, gravitaxis and vertical phototaxis in the green flagellate, Euglena gracilis.

    PubMed

    Hader, D P

    1987-03-01

    A fully automatic computer-controlled video analysis system has been used to study the movement of the green unicellular flagellate, Euglena gracilis in a horizontal or vertical cuvette. In darkness, in the absence of gaseous gradients, most cells swim straight upwards. While in a horizontal cuvette the transition between positive and negative phototaxis is found at about 1.5 W m-2, an excess of 30 W m-2 is required to reverse the upward swimming (due to the combined stimulus of negative gravitaxis and positive phototaxis) in a vertical cuvette. By studying the swimming direction in horizontal and vertical cuvettes in polarized light irradiated from above or from the side, respectively, the dichroic orientation of the photoreceptor molecules can be determined in three dimensions with respect to the axes of the cell; In a horizontal cuvette, in a linearly polarized beam from above, the cells orient predominantly at an angle of about 30 degrees clockwise off the electric dipole transition moment as seen from above. The behavior in a vertical cuvette with polarized light entering from above indicates that the photoreceptor pigments are dichroically oriented 60 degrees counterclockwise from the flagellar plane (seen from the front end of the cell). Experiments with horizontal polarized light indicate that the photoreceptor transition moment deviates 25 degrees clockwise off the long axis of the cell. PMID:11536573

  10. A molecular phylogeny of the flagellated fungi (Chytridiomycota) and description of a new phylum (Blastocladiomycota).

    PubMed

    James, Timothy Y; Letcher, Peter M; Longcore, Joyce E; Mozley-Standridge, Sharon E; Porter, David; Powell, Martha J; Griffith, Gareth W; Vilgalys, Rytas

    2006-01-01

    Chytridiomycota (chytrids) is the only phylum of true Fungi that reproduces with motile spores (zoospores). Chytrids currently are classified into five orders based on habitat, zoospore characters and life cycles. In this paper we estimate the phylogeny of the chytrids with DNA sequences from the ribosomal RNA operon (18S+5.8S+28S subunits). To our surprise the morphologically reduced parasites Olpidium and Rozella comprise two entirely new, and separate, lineages on the fungal tree. Olpidium brassicae groups among the Zygomycota, and Rozella spp. are the earliest branch to diverge in the fungal kingdom. The phylogeny also suggests that Chytridiomycota is not monophyletic and there are four major lineages of chytrids: Rozella spp., Olpidium brassicae, the Blastocladiales and a "core chytrid clade" containing the remaining orders and families and the majority of flagellated fungi. Within the core chytrid group 11 subclades can be identified, each of which correlates well with zoospore ultrastructure or morphology. We provide a synopsis of each clade and its morphological circumscription. The Blastocladiales appears to be the sister taxon of most nonflagellated fungi. Based on molecular phylogenetic and ultrastructural characters this order is elevated to a phylum, the Blastocladiomycota. PMID:17486963

  11. Molecular Analysis of the Graviperception Signal Transduction in the Flagellate Euglena

    NASA Astrophysics Data System (ADS)

    Häder, Donat; Daiker, Viktor; Richter, Peter; Lebert, Michael

    The unicellular flagellate Euglena gracilis perceives and reacts to the gravitational vector of the Earth. Recent results of experiments on parabolic rocket flights have revealed that the orientation can be explained by passive orientation only to a small extend while the remainder relies on an active physiological sensor and an internal sensory transduction chain. Our current working hypothesis is based on the fact that the cellular contents is heavier than the surrounding medium and consequently exerts pressure onto the lower membrane where it activates mechano-sensitive ion channels located at the front end under the trailing flagellum. We recently succeeded in identifying these channels as gene products of the TRP family. RNAi of the corresponding gene abolished graviperception. These channels allow a gated influx of calcium which depolarizes the internal electrical potential and eventually causes a course correction by the flagellar beating. The inwardly gated calcium binds to a specific calmodulin which is likewise an intrinsic element of the signal transduction chain. RNAi of the related mRNA also stopped graviperception. This calmodulin is thought to activate an adenylyl cyclase which generates cyclic AMP which in turn modulates the beating pattern of the flagellum.

  12. Photosynthetic flagellates as model systems for accessing the impact of space conditions on plants

    NASA Astrophysics Data System (ADS)

    Lebert, Michael; Richter, Peter; Häder, Donat

    Plants are an integral part of the exploration attempts for the planned missions to Mars and Moon. Photosynthetic, motile flagellates like Euglena gracilis can serve as model systems for the better understanding of the impact of microgravity and cosmic radiation on plants. Recent parabolic flights indicate that photosynthesis is impaired by microgravity. While oxygen production decreased during the short-term microgravity phases, other photosynthetic parameters remained constant or increased (photosynthetic yield and Ft as indicated by Pulse Amplitude Modulated Fluorescence measurements (PAM)). Ground-based long-term measurements in static bioreactors indicate a strong circadian rhythm of the related PAM-accessible parameters including oxygen production. Besides the problem of scientific analysis of these findings, practical implications with respect to life support systems or controlled environmental systems (CES) are significant. In two FOTON missions a CES system (AQUACELLS and its successor OMEGAHAB) was flown. The detailed analysis is still ongoing. In the paper oxygen production rates are compared to reference experiments on ground. In addition, the results of an upcoming parabolic flight campaign centred around fast PAM kinetics for a closer understanding of the impaired photosynthetic parameters will be presented.

  13. Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

    NASA Astrophysics Data System (ADS)

    Monier, A.; Terrado, R.; Thaler, M.; Comeau, A.; Medrinal, E.; Lovejoy, C.

    2013-06-01

    The ubiquity of heterotrophic flagellates (HFL) in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8-20 μm cell diameter), mostly phagotrophic protists in the upper pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum layer, where light and nutrients are both available. This physically well-characterized system provided an opportunity to explore the community diversity of HFL from different water masses within the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada), targeting the surface, the subsurface chlorophyll maximum layer (SCM) and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1) to examine the possibility of niche differentiation within the stratified water column. Our results strongly suggested that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate-driven changes to the physical structure of the Arctic Ocean.

  14. Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

    NASA Astrophysics Data System (ADS)

    Monier, A.; Terrado, R.; Thaler, M.; Comeau, A. M.; Medrinal, E.; Lovejoy, C.

    2013-02-01

    The ubiquity of heterotrophic flagellates (HFL) in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8-20 μm cell diameter), mostly phagotrophic protists in the pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum (SCM) layer. This physically well-characterized system provided an opportunity to explore the community diversity of HFL across a wide region, and down the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada), targeting the surface, the SCM and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1) to examine the possibility of niche differentiation within the stratified water column. Our results strongly implied that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate driven changes to the physical structure of the Arctic Ocean.

  15. Chemotactic Motility of Pseudomonas fluorescens F113 under Aerobic and Denitrification Conditions

    PubMed Central

    Redondo-Nieto, Miguel; Rivilla, Rafael; Martín, Marta

    2015-01-01

    The sequence of the genome of Pseudomonas fluorescens F113 has shown the presence of multiple traits relevant for rhizosphere colonization and plant growth promotion. Among these traits are denitrification and chemotactic motility. Besides aerobic growth, F113 is able to grow anaerobically using nitrate and nitrite as final electron acceptors. F113 is able to perform swimming motility under aerobic conditions and under anaerobic conditions when nitrate is used as the electron acceptor. However, nitrite can not support swimming motility. Regulation of swimming motility is similar under aerobic and anaerobic conditions, since mutants that are hypermotile under aerobic conditions, such as gacS, sadB, kinB, algU and wspR, are also hypermotile under anaerobic conditions. However, chemotactic behavior is different under aerobic and denitrification conditions. Unlike most pseudomonads, the F113 genome encode three complete chemotaxis systems, Che1, Che2 and Che3. Mutations in each of the cheA genes of the three Che systems has shown that the three systems are functional and independent. Mutation of the cheA1 gene completely abolished swimming motility both under aerobic and denitrification conditions. Mutation of the cheA2 gene, showed only a decrease in swimming motility under both conditions, indicating that this system is not essential for chemotactic motility but is necessary for optimal motility. Mutation of the cheA3 gene abolished motility under denitrification conditions but only produced a decrease in motility under aerobic conditions. The three Che systems proved to be implicated in competitive rhizosphere colonization, being the cheA1 mutant the most affected. PMID:26161531

  16. The suppressive effects of gx-50 on Aβ-induced chemotactic migration of microglia.

    PubMed

    Guo, Yubing; Shi, Shi; Tang, Maoping; Liang, Dongli; Xu, Wangjie; Wang, Lianyun; Wang, Zhaoxia; Qiao, Zhongdong

    2014-04-01

    Microglia, the main immune cells of the central nervous system (CNS), play a vital role in the development of AD. Once microglia are activated, they migrate to neuritic plaques and persistently release pro-inflammatory mediators that lead to neuroinflammation and neuronal degeneration, accelerating the progression of AD. In this study, we analyzed whether an AD candidate drug, N-[2-(3,4-dimethoxyphenyl)ethyl]-3-phenyl-acrylamide (gx-50), a compound extracted from Sichuan pepper (Zanthoxylum bungeanum), exhibited suppressive effects on the chemotactic migration of microglia induced by Aβ. At first, the effects of gx-50 on the migration of primary cultured microglia to Aβ were detected by transwell assay, and the secretion of chemokine CCL5 was measured by ELISA assay. Then, the release of TGF-β1 was detected by ELISA and quantitative real-time PCR, and the activation of the TGF-β1-Smad2 pathway was analyzed by Western blotting. The LDH assay revealed that cell viability was not affected by gx-50 at concentrations from 0.01 to 100 μM; thus, combined with our previous studies, 1 μM was chosen as the treatment concentration. The cell transwell measurement demonstrated that gx-50 suppressed the chemotactic migration of microglia by nearly 50% and inhibited the increase in CCL5 triggered by Aβ. Moreover, the analysis of the TGF-β1-Smad2 pathway revealed that gx-50 can antagonize Aβ-induced down-regulation of TGF-β1 at both the mRNA and protein levels and stimulate the signal pathway activation. Simultaneously, gx-50 pretreatment also significantly enhanced the phosphorylation of glycogen synthase kinase-3β (GSK-3β), which correlated closely with the migration of microglia. In conclusion, in the presence of Aβ, gx-50 pretreatment inhibited the excessive chemotactic migration of microglia. PMID:24508536

  17. A chemotactic signaling surface on CheY defined by suppressors of flagellar switch mutations.

    PubMed Central

    Roman, S J; Meyers, M; Volz, K; Matsumura, P

    1992-01-01

    CheY is the response regulator protein that interacts with the flagellar switch apparatus to modulate flagellar rotation during chemotactic signaling. CheY can be phosphorylated and dephosphorylated in vitro, and evidence indicates that CheY-P is the activated form that induces clockwise flagellar rotation, resulting in a tumble in the cell's swimming pattern. The flagellar switch apparatus is a complex macromolecular structure composed of at least three gene products, FliG, FliM, and FliN. Genetic analysis of Escherichia coli has identified fliG and fliM as genes in which mutations occur that allele specifically suppress cheY mutations, indicating interactions among these gene products. We have generated a class of cheY mutations selected for dominant suppression of fliG mutations. Interestingly, these cheY mutations dominantly suppressed both fliG and fliM mutations; this is consistent with the idea that the CheY protein interacts with both switch gene products during signaling. Biochemical characterization of wild-type and suppressor CheY proteins did not reveal altered phosphorylation properties or evidence for phosphorylation-dependent CheY multimerization. These data indicate that suppressor CheY proteins are specifically altered in the ability to transduce chemotactic signals to the switch at some point subsequent to phosphorylation. Physical mapping of suppressor amino acid substitutions on the crystal structure of CheY revealed a high degree of spatial clustering, suggesting that this region of CheY is a signaling surface that transduces chemotactic signals to the switch. Images PMID:1400175

  18. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity.

    PubMed

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F David; Iii, Roger Smith; Watanabe, Coran M H

    2015-10-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

  19. Cyclocreatine inhibits the production of neutrophil chemotactic factors from isolated hearts.

    PubMed Central

    Elgebaly, S. A.; Allam, M. E.; Rossomando, E. F.; Cordis, G. A.; Forouhar, F.; Farghaly, A.; Kreutzer, D. L.

    1990-01-01

    This study was designed to determine the effect of cyclocreatine on the release of neutrophil chemotactic factors (NCF) from isolated rabbit hearts. We tested the hypothesis that if ischemia is important for the formation of NCF from the myocardium, then blocking (or delaying) ischemic changes with cyclocreatine should inhibit the release of NCF. Two models were used, including (1) perfusion of rabbit hearts (Langendorff apparatus) with oxygenated (95% oxygen) Krebs-Henseleit buffer (K-H buffer) containing 5% cyclocreatine for 120 minutes, and (2) incubating hearts with phosphate-buffered saline (PBS) containing 5% cyclocreatine for 120 minutes. For both models, rabbits were injected intravenously with 10 ml of 5% cyclocreatine solution 30 minutes before the animals were killed and the hearts removed. Control rabbits were injected with 5% creatine solution or saline for 30 minutes before perfusing hearts with K-H buffer or incubating with PBS. Chemotactic activity was assayed in the perfusates and supernatants using modified Boyden chambers and rabbit peritoneal neutrophils as indicator cells. The chemoattractant f-Met-Leu-Phe (f-MLP) was the positive control for a 100% response rate. Isolated hearts perfused with cyclocreatine showed significantly lower chemotactic activity (ie, 1.24 +/- 1% f-MLP; P less than 0.0001) compared to hearts perfused with K-H buffer (129 +/- 18%) or creatine (227 +/- 42%) (mean +/- standard error). Similar results were obtained using incubated hearts. Next the effect of cyclocreatine on neutrophils in the Boyden chamber was determined and it was found that it did not alter neutrophil migration, which excludes a direct inhibitory effect on the cells. Furthermore supernatant from cyclocreatine-treated hearts did not inhibit neutrophil chemotaxis to C5a, indicating absence of a chemotaxis inhibitor in this preparation. Results of these studies suggest that the observed low activity recovered in perfusate and supernatant of cyclocreatine

  20. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity

    PubMed Central

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F. David; Smith, Roger; Watanabe, Coran M. H.

    2015-01-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

  1. Epithelial neutrophil activating peptide-78: a novel chemotactic cytokine for neutrophils in arthritis.

    PubMed Central

    Koch, A E; Kunkel, S L; Harlow, L A; Mazarakis, D D; Haines, G K; Burdick, M D; Pope, R M; Walz, A; Strieter, R M

    1994-01-01

    We and others have shown that cells obtained from inflamed joints of rheumatoid arthritis (RA) patients produce interleukin-8, a potent chemotactic cytokine for neutrophils (PMNs). However, IL-8 accounted for only 40% of the chemotactic activity for PMNs found in these synovial fluids. Currently, we have examined the production of the novel PMN chemotactic cytokine, epithelial neutrophil activating peptide-78 (ENA-78), using peripheral blood, synovial fluid, and synovial tissue from 70 arthritic patients. RA ENA-78 levels were greater in RA synovial fluid (239 +/- 63 ng/ml) compared with synovial fluid from other forms of arthritis (130 +/- 118 ng/ml) or osteoarthritis (2.6 +/- 1.8 ng/ml) (P < 0.05). RA peripheral blood ENA-78 levels (70 +/- 26 ng/ml) were greater than normal peripheral blood levels (0.12 +/- 0.04 ng/ml) (P < 0.05). Anti-ENA-78 antibodies neutralized 42 +/- 9% (mean +/- SE) of the chemotactic activity for PMNs found in RA synovial fluids. Isolated RA synovial tissue fibroblasts in vitro constitutively produced significant levels of ENA-78, and this production was further augmented when stimulated with tumor necrosis factor-alpha (TNF-alpha). In addition RA and osteoarthritis synovial tissue fibroblasts as well as RA synovial tissue macrophages were found to constitutively produce ENA-78. RA synovial fluid mononuclear cells spontaneously produced ENA-78, which was augmented in the presence of lipopolysaccharide. Immunohistochemical localization of ENA-78 from the synovial tissue of patients with arthritis or normal subjects showed that the predominant cellular source of this chemokine was synovial lining cells, followed by macrophages, endothelial cells, and fibroblasts. Synovial tissue macrophages and fibroblasts were more ENA-78 immunopositive in RA than in normal synovial tissue (P < 0.05). These results, which are the first demonstration of ENA-78 in a human disease state, suggest that ENA-78 may play an important role in the recruitment of PMNs

  2. Toll-like receptor 5 is not essential for the promotion of secretory immunoglobulin A antibody responses to flagellated bacteria.

    PubMed

    Hashizume-Takizawa, Tomomi; Yamamoto, Masafumi

    2015-12-01

    Toll-like receptor 5 recognizes bacterial flagellin, plays a critical role in innate immunity, and contributes to flagellin-specific humoral immunity. Further, TLR5-expressing dendritic cells play an important role in IgA synthesis in the intestine; however, the contribution of TLR5 to antigen (Ag)-specific mucosal immunity remains unclear. Thus, whether TLR5 is essential for the induction of intestinal secretory (S)IgA antibody (Ab) responses against flagellin and bacterial Ags attached to the bacterial surface in response to an oral flagellated bacterium, Salmonella, was explored in this study. Our results indicate that when TLR5 knockout (TLR5(-/-)) mice are orally immunized with recombinant Salmonella expressing fragment C of tetanus toxin (rSalmonella-Tox C), tetanus toxoid (TT)- and flagellin (FliC)-specific systemic IgG and intestinal SIgA Abs are elicited. The numbers of TT-specific IgG Ab-forming cells (AFCs) in the spleen and IgA AFCs in the lamina propria (LP) of TLR5(-/-) mice were comparable to those in wild-type mice. rSalmonella-Tox C was equally disseminated in TLR5(-/-) mice, TLR5(-/-) mice lacking Peyer's patches (PPs), and wild-type mice. In contrast, TLR5(-/-) PP-null mice failed to induce TT- and FliC-specific SIgA Abs in the intestine and showed significantly reduced numbers of TT-specific IgA AFCs in the LP. These results suggest that TLR5 is dispensable for the induction of flagellin and surface Ag-specific systemic and mucosal immunity against oral flagellated bacteria. Rather, pathogen recognition, which occurs in PPs, is a prerequisite for the induction of mucosal immunity against flagellated bacteria. PMID:26564803

  3. Diversity of cultured photosynthetic flagellates in the northeast Pacific and Arctic Oceans in summer

    NASA Astrophysics Data System (ADS)

    Balzano, S.; Gourvil, P.; Siano, R.; Chanoine, M.; Marie, D.; Lessard, S.; Sarno, D.; Vaulot, D.

    2012-11-01

    During the MALINA cruise (summer 2009), an extensive effort was undertaken to isolate phytoplankton strains from the northeast (NE) Pacific Ocean, the Bering Strait, the Chukchi Sea, and the Beaufort Sea. In order to characterise the main photosynthetic microorganisms occurring in the Arctic during the summer season, strains were isolated by flow cytometry sorting (FCS) and single cell pipetting before or after phytoplankton enrichment of seawater samples. Strains were isolated both onboard and back in the laboratory and cultured at 4 °C under light/dark conditions. Overall, we isolated and characterised by light microscopy and 18 S rRNA gene sequencing 104 strains of photosynthetic flagellates which grouped into 21 genotypes (defined by 99.5% 18 S rRNA gene sequence similarity), mainly affiliated to Chlorophyta and Heterokontophyta. The taxon most frequently isolated was an Arctic ecotype of the green algal genus Micromonas (Arctic Micromonas), which was nearly the only phytoplankter recovered within the picoplankton (< 2 μm) size range. Strains of Arctic Micromonas as well as other strains from the same class (Mamiellophyceae) were identified in further detail by sequencing the internal transcribed spacer (ITS) region of the rRNA operon. The MALINA Micromonas strains share identical 18 S rRNA and ITS sequences suggesting high genetic homogeneity within Arctic Micromonas. Three other Mamiellophyceae strains likely belong to a new genus. Other green algae from the genera Nephroselmis, Chlamydomonas, and Pyramimonas were also isolated, whereas Heterokontophyta included some unidentified Pelagophyceae, Dictyochophyceae (Pedinellales), and Chrysophyceae (Dinobryon faculiferum). Moreover, we isolated some Cryptophyceae (Rhodomonas sp.) as well as a few Prymnesiophyceae and dinoflagellates. We identified the dinoflagellate Woloszynskia cincta by scanning electron microscopy (SEM) and 28 S rRNA gene sequencing. Our morphological analyses show that this species possess

  4. Diversity of cultured photosynthetic flagellates in the North East Pacific and Arctic Oceans in summer

    NASA Astrophysics Data System (ADS)

    Balzano, S.; Gourvil, P.; Siano, R.; Chanoine, M.; Marie, D.; Lessard, S.; Sarno, D.; Vaulot, D.

    2012-06-01

    During the MALINA cruise (summer 2009) an extensive effort was undertaken to isolate phytoplankton strains from the North East (NE) Pacific Ocean, the Bering Strait, and the Beaufort Sea. Strains were isolated by flow cytometry sorting (FCS) and pipetting before or after phytoplankton enrichment of seawater samples. Strains were isolated both onboard and back in the laboratory and cultured at 4 °C under light/dark conditions. Overall, we isolated and characterised by light microscopy and 18S rRNA gene sequencing 104 strains of photosynthetic flagellates which grouped into 21 genotypes (defined by 99.5% 18S rRNA gene sequence similarity) mainly affiliated to Chlorophyta and Heterokontophyta. The taxon most frequently isolated was an Arctic ecotype of the green algal genus Micromonas (Arctic Micromonas) which was almost the only phytoplankter recovered within picoplankton (≤ 2 μm) size range. Strains of Arctic Micromonas as well as three unidentified strains related to the same genus were identified in further details by sequencing the Internal Transcribed Spacer (ITS) region of the rRNA operon. The MALINA Micromonas strains share identical 18S rRNA and ITS sequences suggesting high genetic homogeneity within Arctic Micromonas. The unidentified strains form a genotype likely belonging to a new genus within the family Mamiellaceae to which Micromonas belongs. Other green algae genotypes from the genera Nephroselmis, Chlamydomonas, Pyramimonas were also isolated whereas Heterokontophyta included Pelagophyceae, Dictyochophyceae and Chrysophyceae. Dictyochophyceae included Pedinellales which could not be identified to the genus level whereas Chrysophyceae comprised Dinobryon faculiferum. Moreover, we isolated Rhodomonas sp. as well as a few Haptophyta and dinoflagellates. We identified the dinoflagellate Woloszynskia cincta by Scanning Electron Microscopy (SEM) and 28S rRNA gene sequencing. Our morphological analyses show that this species possess the diagnostic

  5. Video processing analysis for the determination and evaluation of the chemotactic response in bacterial populations.

    PubMed

    Nisenbaum, Melina; Maldonado, Emilio; Martínez Arca, Jorge; González, Jorge F; Passoni, Lucía I; Murialdo, Silvia E

    2016-08-01

    The aim of the present work was to design a methodology based on video processing to obtain indicators of bacterial population motility that allow the quantitative and qualitative analysis and comparison of the chemotactic phenomenon with different attractants in the agarose-in plug bridge method. Video image sequences were processed applying Shannon's entropy to the intensity time series of each pixel, which conducted to a final pseudo colored image resembling a map of the dynamic bacterial clusters. Processed images could discriminate perfectly between positive and negative attractant responses at different periods of time from the beginning of the assay. An index of spatial and temporal motility was proposed to quantify the bacterial response. With this index, this video processing method allowed obtaining quantitative information of the dynamic changes in space and time from a traditional qualitative assay. We conclude that this computational technique, applied to the traditional agarose-in plug assay, has demonstrated good sensitivity for identifying chemotactic regions with a broad range of motility. PMID:27291715

  6. Chemotactic behavior of deep subsurface bacteria toward carbohydrates, amino acids and a chlorinated alkene

    SciTech Connect

    Lopez de Victoria, G. . Dept. of Biology)

    1989-02-01

    The chemotactic behavior of deep terrestrial subsurface bacteria toward amino acids, carbohydrates and trichloroethylene was assayed using a modification of the capillary method and bacterial enumeration by acridine orange direct counts. Eleven isolates of bacteria isolated from six different geological formations were investigated. A bimodal response rather than an absolute positive or negative response was observed in most assays. Most of the isolates were positively chemotactic to low concentrations of substrates and were repelled by high concentrations of the same substrate. However, this was not the case for trichloroethylene (TCE) which was mostly an attractant and elicited the highest responses in all the isolates when compared with amino acids and carbohydrates. The movement rates of these isolates in aseptic subsurface sediments in the absence and presence of TCE were also determined using a laboratory model. All of the isolates showed distinct response range, peak, and threshold concentrations when exposed to the same substrates suggesting that they are possibly different species as has been inferred from DNA homology studies. 101 refs., 4 figs., 57 tabs.

  7. Modeling of chemotactic steering of bacteria-based microrobot using a population-scale approach.

    PubMed

    Cho, Sunghoon; Choi, Young Jin; Zheng, Shaohui; Han, Jiwon; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2015-09-01

    The bacteria-based microrobot (Bacteriobot) is one of the most effective vehicles for drug delivery systems. The bacteriobot consists of a microbead containing therapeutic drugs and bacteria as a sensor and an actuator that can target and guide the bacteriobot to its destination. Many researchers are developing bacteria-based microrobots and establishing the model. In spite of these efforts, a motility model for bacteriobots steered by chemotaxis remains elusive. Because bacterial movement is random and should be described using a stochastic model, bacterial response to the chemo-attractant is difficult to anticipate. In this research, we used a population-scale approach to overcome the main obstacle to the stochastic motion of single bacterium. Also known as Keller-Segel's equation in chemotaxis research, the population-scale approach is not new. It is a well-designed model derived from transport theory and adaptable to any chemotaxis experiment. In addition, we have considered the self-propelled Brownian motion of the bacteriobot in order to represent its stochastic properties. From this perspective, we have proposed a new numerical modelling method combining chemotaxis and Brownian motion to create a bacteriobot model steered by chemotaxis. To obtain modeling parameters, we executed motility analyses of microbeads and bacteriobots without chemotactic steering as well as chemotactic steering analysis of the bacteriobots. The resulting proposed model shows sound agreement with experimental data with a confidence level <0.01. PMID:26487902

  8. Protection against lethal bacterial infection in mice by monocyte-chemotactic and -activating factor.

    PubMed Central

    Nakano, Y; Kasahara, T; Mukaida, N; Ko, Y C; Nakano, M; Matsushima, K

    1994-01-01

    Chemotactic factors regulate the recruitment of neutrophils, lymphocytes, or monocytes-macrophages to infectious and inflammatory sites. The purpose of this study was to determine whether monocyte-chemotactic and -activating factor (MCAF [MCP-1], a JE gene product) also influences the host defense mechanism against microbial infection. We evaluated the effect of recombinant human MCAF on the survival rate of mice systemically infected with Pseudomonas aeruginosa or Salmonella typhimurium. The administration of 2.5 micrograms of MCAF 6 h before infection completely protected the mice from lethal infection. Mice with cyclophosphamide-induced leukopenia exhibiting increased susceptibility to P. aeruginosa were also endowed with resistance by the same dose of MCAF. Administration of MCAF at -6 h was critical, since MCAF given either earlier or later than -6 h failed to rescue mice from lethal infection. The in vivo effect on the survival of mice paralleled the reduced recovery of viable P. aeruginosa or S. typhimurium from the peritoneal cavity, i.e., the number of recovered bacteria from the MCAF (2.5 micrograms per mouse)-treated mice was reduced to less than 2% of control mice for P. aeruginosa and 4% of control mice for S. typhimurium at 24 h. Since MCAF exhibited chemotaxis on murine macrophages as well as enhanced phagocytosis and killing of bacteria in vitro, the activation of macrophages, followed by the recruitment into the peritoneal cavity, is responsible for eliminating bacteria and thus enhancing the survival rate. PMID:8300198

  9. Distinct CCR7 glycosylation pattern shapes receptor signaling and endocytosis to modulate chemotactic responses.

    PubMed

    Hauser, Mark A; Kindinger, Ilona; Laufer, Julia M; Späte, Anne-Katrin; Bucher, Delia; Vanes, Sarah L; Krueger, Wolfgang A; Wittmann, Valentin; Legler, Daniel F

    2016-06-01

    The homeostatic chemokines CCL19 and CCL21 and their common cognate chemokine receptor CCR7 orchestrate immune cell trafficking by eliciting distinct signaling pathways. Here, we demonstrate that human CCR7 is N-glycosylated on 2 specific residues in the N terminus and the third extracellular loop. Conceptually, CCR7 glycosylation adds steric hindrance to the receptor N terminus and extracellular loop 3, acting as a "swinging door" to regulate receptor sensitivity and cell migration. We found that freshly isolated human B cells, as well as expanded T cells, but not naïve T cells, express highly sialylated CCR7. Moreover, we identified that human dendritic cells imprint T cell migration toward CCR7 ligands by secreting enzymes that deglycosylate CCR7, thereby boosting CCR7 signaling on T cells, permitting enhanced T cell locomotion, while simultaneously decreasing receptor endocytosis. In addition, dendritic cells proteolytically convert immobilized CCL21 to a soluble form that is more potent in triggering chemotactic movement and does not desensitize the receptor. Furthermore, we demonstrate that soluble CCL21 functionally resembles neither the CCL19 nor the CCL21 phenotype but acts as a chemokine with unique features. Thus, we advance the concept of dendritic cell-dependent generation of micromilieus and lymph node conditioning by demonstrating a novel layer of CCR7 regulation through CCR7 sialylation. In summary, we demonstrate that leukocyte subsets express distinct patterns of CCR7 sialylation that contribute to receptor signaling and fine-tuning chemotactic responses. PMID:26819318

  10. A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

    PubMed Central

    Sanders, Lisa; Andermann, Tessa M.

    2013-01-01

    Directed motility, or chemotaxis, is required for Helicobacter pylori to establish infection in the stomach, although the full repertoire of this bacterium’s chemotactic responses is not yet known. Here we report that H. pylori responds to zinc as an attractant and nickel as a repellent. To reach this conclusion, we employed both a temporal chemotaxis assay based on bacterial reversals and a supplemented soft agar spatial assay. We refined the temporal assay using a previously described chemorepellent, acid, and found that H. pylori requires rich media with serum to maintain optimal swimming motility. Surprisingly, we found that some strains respond to acid as an attractant, and that the TlpC chemoreceptor correlated with whether acid was sensed as an attractant or repellent. Using this same assay, we detected weak repellent responses to nickel and copper, and a varied response to zinc. We thus developed an alternative spatial chemotactic assay called the supplemented soft agar assay, which utilizes soft agar medium supplemented with the test compound. With Escherichia coli, the attractant serine slowed overall bacterial migration, while the repellent nickel increased the speed of overall migration. In H. pylori we detected slowed migration with doubled tryptone media, as well as zinc, consistent with an attractant response. In contrast, nickel increased migration, consistent with repulsion. PMID:23139399

  11. Syndecan-4 regulates the bFGF-induced chemotactic migration of endothelial cells.

    PubMed

    Li, Ran; Wu, Han; Xie, Jun; Li, Guannan; Gu, Rong; Kang, Lina; Wang, Lian; Xu, Biao

    2016-10-01

    Chemotactic migration of endothelial cells (ECs) guided by extracellular attractants is essential for blood vessel formation. Synd4 is a ubiquitous heparin sulfate proteoglycan receptor on the cell surface that has been identified to promote angiogenesis during tissue repair. Here, the role synd4 played in chemotactic migration of ECs was investigated in vitro and in vivo. Human umbilical vein endothelial cells (HUVECs) were transfected with Lenti-synd4-RNAi or Lenti-null. Cell migration was observed in a 2D-chemotaxis slide with a stable gradient of basic fibroblast growth factor (bFGF) for 18 h using time-lapse microscopy. Synd4 knockdown HUVECs showed reduced mobility compared with the control. In animal studies, Matrigel premixed with bFGF was used to induce the migration of ECs. The cells migrated less distance from the skin in the Matrigel plugs of synd4 null mice compared with the control mice. Then recombinant adenoviruses containing the synd4 gene (Ad-synd4) or null (Ad-null) were constructed to enhance the synd4 expression of migratory cells in Matrigel plugs of wild-type mice. Migratory cells with synd4 overexpression did not invade further in the Matrigel plugs of wild-type mice, but showed a high ability to proliferate. PMID:27541034

  12. Sensitivity of the rate of nutrient uptake by chemotactic bacteria to physical and biological parameters in a turbulent environment.

    PubMed

    Watteaux, Romain; Stocker, Roman; Taylor, John R

    2015-12-21

    In this study, we use direct numerical simulations (DNS) to investigate the response of chemotactic bacteria to an isolated patch of chemoattractant in a turbulent environment. Previous work has shown that by stirring nutrients that are chemoattractants into a network of thin, elongated filaments, turbulence directly influences the rate at which chemotactic bacteria consume nutrients. However, the quantitative outcome of this process is influenced by a host of physical and biological factors, and many of these remain unexplored. Here, we analyse the sensitivity of nutrient uptake by chemotactic bacteria on a wide range of physical and biological parameters using a series of controlled DNS. Starting with uniformly distributed populations of motile and non-motile bacteria in a fully developed homogeneous, isotropic turbulent flow, we inject a patch of dissolved nutrients. We then assess the chemotactic advantage, defined as the difference between the nutrients consumed by motile and non-motile bacteria over the lifetime of the patch. We find that the chemotaxis can enhance the total uptake rate by a factor of 1.6 and allows the population of chemotactic bacteria to absorb nutrients 2.2 times faster than non-motile bacteria Results show that chemotactic bacteria are subject to a trade-off between swimming to leave regions devoid of nutrients and, once a nutrient gradient is detected, staying in regions of large nutrient concentration. These findings could help explain how the physical characteristics of turbulent marine ecosystems influence the optimal biological traits of bacteria through the competition for limited resources. PMID:26392215

  13. Transcriptional regulation of coordinate changes in flagellar mRNAs during differentiation of Naegleria gruberi amoebae into flagellates

    SciTech Connect

    Lee, J.H.; Walsh, C.J.

    1988-06-01

    The nuclear run-on technique was used to measure the rate of transcription of flagellar genes during the differentiation of Naegleria gruberi amebae into flagellates. Synthesis of mRNAs for the axonemal proteins ..cap alpha..- and BETA-tubulin and flagellar calmodulin, as well as a coordinately regulated poly(A)/sup +/ RNA that codes for an unidentified protein, showed transient increases averaging 22-fold. The rate of synthesis of two poly(A)/sup +/ RNAs common to ameobae and flagellates was low until the transcription of the flagellar genes began to decline, at which time synthesis of the RNAs found in ameobae increased 3- to 10-fold. The observed changes in the rate of transcription can account quantitatively for the 20-fold increase in flagellar mRNA concentration during the differentiation. The data for the flagellar calmodulin gene demonstrate transcriptional regulation for a nontubulin axonemal protein. The data also demonstrate at least two programs of transcriptional regulation during the differentiation and raise the intriguing possibility that some significant fraction of the nearly 200 different proteins of the flagellar axoneme is transcriptionally regulated during the 1 h it takes N. gruberi amebae to form visible flagella.

  14. The candidate phylum 'Termite Group 1' of bacteria: phylogenetic diversity, distribution, and endosymbiont members of various gut flagellated protists.

    PubMed

    Ohkuma, Moriya; Sato, Tomoyuki; Noda, Satoko; Ui, Sadaharu; Kudo, Toshiaki; Hongoh, Yuichi

    2007-06-01

    The candidate phylum 'Termite Group 1' (TG1) of bacteria, which is abundant in termite guts but has no culturable representative, was investigated with respect to the in situ localization, distribution, and diversity. Based on the 16S rRNA gene sequence analyses and FISH in termite guts, a number of lineages of TG1 members were identified as endosymbionts of a variety of gut flagellated protists from the orders Trichonymphida, Cristamonadida, and Oxymonadida that are mostly unique to termites. However, the survey in various environments using specific PCR primers revealed that TG1 members were also present in termites, a cockroach, and the bovine rumen that typically lack these protist orders. Most of the TG1 members from gut flagellates, termites, cockroaches, and the rumen formed a monophyletic subcluster that showed a shallow branching pattern in the phylogenetic tree, suggesting their recent diversification. Although endosymbionts of the same protist genera tended to be closely related, the endosymbiont lineages were often independent of the higher level classifications of their host protist and were dispersed in the phylogenetic tree. It appears that their cospeciation is not the sole rule for the diversification of TG1 members of endosymbionts. PMID:17391329

  15. TAXONOMIC STUDY OF TWO NEW GENERA OF FUSIFORM GREEN FLAGELLATES, TABRIS GEN. NOV. AND HAMAKKO GEN. NOV. (VOLVOCALES, CHLOROPHYCEAE)(1).

    PubMed

    Nakada, Takashi; Nozaki, Hisayoshi

    2009-04-01

    On the basis of LM, we isolated strains of two species of fusiform green flagellates that could be assigned to former Chlorogonium (Cg.) Ehrenb. One species, "Cg."heimii Bourr., lacked a pyrenoid in its vegetative cells and required organic compounds for growth. The other was similar to Cg. elongatum (P. A. Dang.) Francé and "Cg."acus Nayal, but with slightly smaller vegetative cells. Their molecular phylogeny was also studied based on combined 18S rRNA, RUBISCO LSU (rbcL), and P700 chl a-apoprotein A2 (psaB) gene sequences. Both species were separated from Chlorogonium emend., Gungnir Nakada and Rusalka Nakada, which were formerly assigned to Chlorogonium. They were accordingly assigned to new genera, Tabris Nakada gen. nov. and Hamakko (Hk.) Nakada gen. nov. as T. heimii (Bourr.) Nakada comb. nov. and Hk. caudatus Nakada sp. nov., respectively. Tabris is differentiated from other genera of fusiform green flagellates by its vegetative cells, which only have two apical contractile vacuoles and lack a pyrenoid in the chloroplast. Hamakko, on the other hand, is distinguishable by the fact that its pyrenoids in vegetative cells are penetrated by flattened thylakoid lamellae. PMID:27033826

  16. The pathogenic amoeboflagellate Naegleria fowleri: environmental isolations, competitors, ecologic interactions, and the flagellate-empty habitat hypothesis.

    PubMed

    Griffin, J L

    1983-05-01

    From several surveys of environmental sites, the virulent human pathogen, Naegleria fowleri, was isolated from a pond in Georgia, a sewage treatment plant in Missouri, and from the Potomac and Anacostia rivers near and in Washington, D.C. Widely scattered, sparse populations seemed only a potential threat to human health at the time of sampling. The data support an estimate that the sites sampled contain 10,000 typical, low temperature, bactivorous amoebae for each heat tolerant amoeba able to grow at 45 degrees C. Heat tolerant competitors were much more common than N. fowleri. Naegleria lovaniensis, which is heat tolerant but nonpathogenic, was isolated from and downstream from an open air thermal pollution temperature gradient. Hot piles of composting sewage sludge yielded no amoeboflagellates, many heat tolerant (45-49 degrees C) amoebae, and one thermophilic (52 degrees C) Acanthamoeba. Features of the methods used include two-stage incubation to increase isolation of sparse organisms and distinction of N. fowleri from almost all other amoebae on agar plates. The flagellate-empty habitat hypothesis postulates a general model in which human intervention and/or natural events remove usual competitors and the ability to transform to a motile flagellate confers an advantage in recolonizing. PMID:6631781

  17. Flagellated Algae Protein Evolution Suggests the Prevalence of Lineage-Specific Rules Governing Evolutionary Rates of Eukaryotic Proteins

    PubMed Central

    Chang, Ting-Yan; Liao, Ben-Yang

    2013-01-01

    Understanding the general rules governing the rate of protein evolution is fundamental to evolutionary biology. However, attempts to address this issue in yeasts and mammals have revealed considerable differences in the relative importance of determinants for protein evolutionary rates. This phenomenon was previously explained by the fact that yeasts and mammals are different in many cellular and genomic properties. Flagellated algae species have several cellular and genomic characteristics that are intermediate between yeasts and mammals. Using partial correlation analyses on the evolution of 6,921 orthologous proteins from Chlamydomonas reinhardtii and Volvox carteri, we examined factors influencing evolutionary rates of proteins in flagellated algae. Previous studies have shown that mRNA abundance and gene compactness are strong determinants for protein evolutionary rates in yeasts and mammals, respectively. We show that both factors also influence algae protein evolution with mRNA abundance having a larger impact than gene compactness on the rates of algae protein evolution. More importantly, among all the factors examined, coding sequence (CDS) length has the strongest (positive) correlation with protein evolutionary rates. This correlation between CDS length and the rates of protein evolution is not due to alignment-related issues or domain density. These results suggest no simple and universal rules governing protein evolutionary rates across different eukaryotic lineages. Instead, gene properties influence the rate of protein evolution in a lineage-specific manner. PMID:23563973

  18. Development and application of a most-probable-number-pcr assay to quantify flagellate populations in soil samples.

    PubMed

    Fredslund, L; Ekelund, F; Jacobsen, C S; Johnsen, K

    2001-04-01

    This paper reports on the first successful molecular detection and quantification of soil protozoa. Quantification of heterotrophic flagellates and naked amoebae in soil has traditionally relied on dilution culturing techniques, followed by most-probable-number (MPN) calculations. Such methods are biased by differences in the culturability of soil protozoa and are unable to quantify specific taxonomic groups, and the results are highly dependent on the choice of media and the skills of the microscopists. Successful detection of protozoa in soil by DNA techniques requires (i) the development and validation of DNA extraction and quantification protocols and (ii) the collection of sufficient sequence data to find specific protozoan 18S ribosomal DNA sequences. This paper describes the development of an MPN-PCR assay for detection of the common soil flagellate Heteromita globosa, using primers targeting a 700-bp sequence of the small-subunit rRNA gene. The method was tested by use of gnotobiotic laboratory microcosms with sterile tar-contaminated soil inoculated with the bacterium Pseudomonas putida OUS82 UCB55 as prey. There was satisfactory overall agreement between H. globosa population estimates obtained by the PCR assay and a conventional MPN assay in the three soils tested. PMID:11282613

  19. Flagellated algae protein evolution suggests the prevalence of lineage-specific rules governing evolutionary rates of eukaryotic proteins.

    PubMed

    Chang, Ting-Yan; Liao, Ben-Yang

    2013-01-01

    Understanding the general rules governing the rate of protein evolution is fundamental to evolutionary biology. However, attempts to address this issue in yeasts and mammals have revealed considerable differences in the relative importance of determinants for protein evolutionary rates. This phenomenon was previously explained by the fact that yeasts and mammals are different in many cellular and genomic properties. Flagellated algae species have several cellular and genomic characteristics that are intermediate between yeasts and mammals. Using partial correlation analyses on the evolution of 6,921 orthologous proteins from Chlamydomonas reinhardtii and Volvox carteri, we examined factors influencing evolutionary rates of proteins in flagellated algae. Previous studies have shown that mRNA abundance and gene compactness are strong determinants for protein evolutionary rates in yeasts and mammals, respectively. We show that both factors also influence algae protein evolution with mRNA abundance having a larger impact than gene compactness on the rates of algae protein evolution. More importantly, among all the factors examined, coding sequence (CDS) length has the strongest (positive) correlation with protein evolutionary rates. This correlation between CDS length and the rates of protein evolution is not due to alignment-related issues or domain density. These results suggest no simple and universal rules governing protein evolutionary rates across different eukaryotic lineages. Instead, gene properties influence the rate of protein evolution in a lineage-specific manner. PMID:23563973

  20. Monocyte chemotactic protein-1 deficiency reduces spontaneous metastasis of Lewis lung carcinoma in mice fed a high-fat diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Obesity is a risk factor for cancer. Adipose tissue produces pro-inflammatory adipokines that contribute obesity-related malignant progression. This study investigated the effects of monocyte chemotactic protein-1 (MCP-1) deficiency on pulmonary metastasis of Lewis lung carcinoma (LLC) in male C57...

  1. Actinobacillus actinomycetemcomitans serotype b-specific polysaccharide antigen stimulates production of chemotactic factors and inflammatory cytokines by human monocytes.

    PubMed Central

    Yamaguchi, N; Yamashita, Y; Ikeda, D; Koga, T

    1996-01-01

    Serotype b-specific polysaccharide antigen (SPA) was extracted from whole cells of Actinobacillus actinomycetemcomitans Y4 by autoclaving and purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300. SPA induced the release of monocyte and leukocyte chemotactic factors by human monocytes. Polymyxin B had almost no effect on the release of monocyte chemotactic factor, but a monoclonal antibody against SPA markedly inhibited it. Human monocytes stimulated with SPA exhibited the increased mRNA expression of monocyte chemoattractant protein 1 (MCP-1) and a neutrophil chemotactic factor, interleukin-8 (IL-8). On the other hand, SPA induced the release of IL-1, IL-6, and tumor necrosis factor (TNF) and enhanced the expression of IL-1alpha, IL-1beta, IL-6, and TNF alpha (TNF-alpha) mRNAs. Human monocytes expressed MCP-1 and IL-8 mRNAs when stimulated by human recombinant IL-1alpha, I1-1beta, IL-6, and TNF-alpha, suggesting that these inflammatory cytokines induced by SPA might participate in the production of chemotactic factors in human monocytes. PMID:8698480

  2. Study of the Chemotactic Response of Multicellular Spheroids in a Microfluidic Device

    PubMed Central

    Ayuso, Jose M.; Basheer, Haneen A.; Monge, Rosa; Sánchez-Álvarez, Pablo; Doblaré, Manuel; Shnyder, Steven D.; Vinader, Victoria; Afarinkia, Kamyar

    2015-01-01

    We report the first application of a microfluidic device to observe chemotactic migration in multicellular spheroids. A microfluidic device was designed comprising a central microchamber and two lateral channels through which reagents can be introduced. Multicellular spheroids were embedded in collagen and introduced to the microchamber. A gradient of fetal bovine serum (FBS) was established across the central chamber by addition of growth media containing serum into one of the lateral channels. We observe that spheroids of oral squamous carcinoma cells OSC–19 invade collectively in the direction of the gradient of FBS. This invasion is more directional and aggressive than that observed for individual cells in the same experimental setup. In contrast to spheroids of OSC–19, U87-MG multicellular spheroids migrate as individual cells. A study of the exposure of spheroids to the chemoattractant shows that the rate of diffusion into the spheroid is slow and thus, the chemoattractant wave engulfs the spheroid before diffusing through it. PMID:26444904

  3. Study of the Chemotactic Response of Multicellular Spheroids in a Microfluidic Device.

    PubMed

    Ayuso, Jose M; Basheer, Haneen A; Monge, Rosa; Sánchez-Álvarez, Pablo; Doblaré, Manuel; Shnyder, Steven D; Vinader, Victoria; Afarinkia, Kamyar; Fernández, Luis J; Ochoa, Ignacio

    2015-01-01

    We report the first application of a microfluidic device to observe chemotactic migration in multicellular spheroids. A microfluidic device was designed comprising a central microchamber and two lateral channels through which reagents can be introduced. Multicellular spheroids were embedded in collagen and introduced to the microchamber. A gradient of fetal bovine serum (FBS) was established across the central chamber by addition of growth media containing serum into one of the lateral channels. We observe that spheroids of oral squamous carcinoma cells OSC-19 invade collectively in the direction of the gradient of FBS. This invasion is more directional and aggressive than that observed for individual cells in the same experimental setup. In contrast to spheroids of OSC-19, U87-MG multicellular spheroids migrate as individual cells. A study of the exposure of spheroids to the chemoattractant shows that the rate of diffusion into the spheroid is slow and thus, the chemoattractant wave engulfs the spheroid before diffusing through it. PMID:26444904

  4. Characterization of neutrophil and monocyte specific chemotactic factors derived from the cornea in response to hydrogen peroxide injury.

    PubMed Central

    Elgebaly, S. A.; Herkert, N.; O'Rourke, J.; Kreutzer, D. L.

    1987-01-01

    To unravel the contributions of corneal tissue in endocular inflammation, we examined the capability of corneal endothelial cells (CECs) to release leukocyte chemotactic factors (LCFs) following injury induced by the leukocyte product hydrogen peroxide. Hydrogen peroxide (H2O2) was chemically generated by the interactions of glucose and glucose oxidase prepared in serum-free minimal essential medium (MEM). For these studies, endothelial surfaces of isolated bovine corneas were incubated with glucose (1 mg/ml) and glucose oxidase (20 U/ml) for 4, 6, and 10 hours at 37 C/in a 5% CO2 atmosphere. Supernatants were then removed and assayed for bovine neutrophil or mononuclear cell chemotactic activity. C5 fragment was our positive control for 100% chemotactic response. Corneas were also fixed in buffered formalin for histopathologic evaluation. Results of these studies indicated that 1) 6-hour interactions of the glucose (G)/glucose oxidase (GO) mixture with endothelial surfaces resulted in both endothelial cell injury (cytoplasmic vacuolization and convoluted nuclei) and production of chemotactic factors (via checkerboard analysis) specific for both neutrophils (58% maximum chemotactic response [MCR]) and mononuclear cells (75% MCR); 2) control corneas treated with either G or GO for 4 and 6 hours produced low levels of LCFs (5-15% MCR); 3) preliminary molecular weight characterization of cornea-derived LCFs obtained from corneas incubated with G/GO for 6 hours revealed the detection of chemotactic activity specific for mononuclear cells in two major fractions, one near the void volume (greater than 130,000 daltons) and one near the elution volume (less than or equal to 10,000-15,000 daltons). Chemotactic activity specific for neutrophils was detected only in one major fraction near the elution volume (less than or equal to 10,000-15,000 daltons); and 4) the production of these LCFs by isolated corneas was significantly inhibited, in a dose-response fashion, when the

  5. Transverse Chemotactic Migration of Bacteria from High to Low Permeability Regions in a Dual Permeability Porous Microfluidic Device

    NASA Astrophysics Data System (ADS)

    Singh, R.; Olson, M. S.

    2011-12-01

    Low permeability regions sandwiched between high permeability regions such as clay lenses are difficult to treat using conventional treatment methods. Trace concentrations of contaminants such as non-aqueous phase liquids (NAPLs) remain trapped in these regions and over the time diffuse out into surrounding water thereby acting as a long term source of groundwater contamination. Bacterial chemotaxis (directed migration toward a contaminant source), may be helpful in enhancing bioremediation of such contaminated sites. This study is focused on simulating a two-dimensional dual-permeability groundwater contamination scenario using microfluidic devices and evaluating transverse chemotactic migration of bacteria from high to low permeability regions. A novel bi-layer polydimethylsiloxane (PDMS) microfluidic device was fabricated using photolithography and soft lithography techniques to simulate contamination of a dual- permeability region due to leakage from an underground storage tank into a low permeability region. This device consists of a porous channel through which a bacterial suspension (Escherchia Coli HCB33) is flown and another channel for injecting contaminant/chemo-attractant (DL-aspertic acid) into the porous channel. The pore arrangement in the porous channel contains a 2-D low permeability region surrounded by high permeability regions on both sides. Experiments were performed under chemotactic and non-chemotactic (replacing attractant with buffer solution in the non porous channel) conditions. Images were captured in transverse pore throats at cross-sections 4.9, 9.8, and 19.6 mm downstream from the attractant injection point and bacteria were enumerated in the middle of each pore throat. Bacterial chemotaxis was quantified in terms of the change in relative bacterial counts in each pore throat at cross-sections 9.8 and 19.6 mm with respect to counts at the cross-section at 4.9 mm. Under non-chemotactic conditions, relative bacterial count was observed

  6. ABCA2 transporter deficiency reduces incidence of TRAMP prostate tumor metastasis and cellular chemotactic migration

    PubMed Central

    Mack, Jody T.; Helke, Kristi L.; Normand, Gabrielle; Green, CoDanielle; Townsend, Danyelle M.; Tew, Kenneth D.

    2010-01-01

    In order to study the effects of ATP-binding cassette transporter 2 (ABCA2) deficiency on the progression of prostate cancer, congenic Abca2 knockout (KO) mice were crossed to the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. ABCA2 expression was elevated in wild-type/TRAMP (WT/Tg) dorsal prostate, a region comprising the most aggressive tumors in this model, compared to non-transgenic WT mice. Primary prostate tumor progression was similar in KO/Tg and WT/Tg mice with respect to pathological score, prostate tumor growth, as calculated using MRI volumetry, and proliferative index, as determined by PCNA immunostaining. Vimentin, a marker of the epithelial-mesenchymal transition, was expressed at similar levels in prostate, but elevated in histologically normal seminal vesicles (SV) in KO/Tg mice (P < 0.02), concomitant with an increased SV volume (P < 0.01). These changes in the SV did not exacerbate the metastatic phenotype of this disease model; rather, KO/Tg mice aged 20-25 weeks had no detectable metastases while 38% of WT/Tg developed metastases to lung and/or lymph nodes. The absence of a metastatic phenotype in KO/Tg mice was reprised in stable ABCA2 knockdown (KD) cells where chemotactic, but not random, migration was impaired (P = 0.0004). Expression levels of sphingolipid biosynthetic enzymes were examined due to the established link of the transporter with sphingolipid homeostasis. Galactosylceramide synthase (GalCerS) mRNA levels were over 8-fold higher in KD cells (P = 0.001), while lactosylceramide synthase (LacCerS) and CTP:choline cytidylyltransferase (CCT) were significantly reduced (P < 0.0001 and 0.03, respectively). Overall, we demonstrate that ABCA2 deficiency inhibits prostate tumor metastasis in vivo and decreases chemotactic potential of cells, conceivably due to altered sphingolipid metabolism. PMID:21041019

  7. Altered chemotactic response to CXCL12 in patients carrying GATA2 mutations.

    PubMed

    Maciejewski-Duval, Anna; Meuris, Floriane; Bignon, Alexandre; Aknin, Marie-Laure; Balabanian, Karl; Faivre, Laurence; Pasquet, Marlène; Barlogis, Vincent; Fieschi, Claire; Bellanné-Chantelot, Christine; Donadieu, Jean; Schlecht-Louf, Géraldine; Marin-Esteban, Viviana; Bachelerie, Françoise

    2016-06-01

    GATA2 deficiency-formerly described as MonoMAC syndrome; dendritic cells, monocytes, B cells, and natural killer cell deficiency; familial myelodysplastic syndrome/acute myeloid leukemia; or Emberger syndrome-encompasses a range of hematologic and nonhematologic anomalies, mainly characterized by monocytopenia, B lymphopenia, natural killer cell cytopenia, neutropenia, immunodeficiency, and a high risk of developing acute myeloid leukemia. Herein, we present 7 patients with GATA2 deficiency recruited into the French Severe Chronic Neutropenia Registry, which enrolls patients with all kinds of congenital neutropenia. We performed extended immunophenotyping of their whole blood lymphocyte populations, together with the analysis of their chemotactic responses. Lymphopenia was recorded for B and CD4(+) T cells in 6 patients. Although only 3 patients displayed natural killer cell cytopenia, the CD56(bright) natural killer subpopulation was nearly absent in all 7 patients. Natural killer cells from 6 patients showed decreased CXCL12/CXCR4-dependent chemotaxis, whereas other lymphocytes, and most significantly B lymphocytes, displayed enhanced CXCL12-induced chemotaxis compared with healthy volunteers. Surface expression of CXCR4 was significantly diminished in the patients' natural killer cells, although the total expression of the receptor was found to be equivalent to that of natural killer cells from healthy individual controls. Together, these data reveal that GATA2 deficiency is associated with impaired membrane expression and chemotactic dysfunctions of CXCR4. These dysfunctions may contribute to the physiopathology of this deficiency by affecting the normal distribution of lymphocytes and thus potentially affecting the susceptibility of patients to associated infections. PMID:26710799

  8. Complete Genome Sequence of Endomicrobium proavitum, a Free-Living Relative of the Intracellular Symbionts of Termite Gut Flagellates (Phylum Elusimicrobia)

    PubMed Central

    Zheng, Hao

    2015-01-01

    We sequenced the complete genome of Endomicrobium proavitum strain Rsa215, the first isolate of the class Endomicrobia (phylum Elusimicrobia). It is the closest free-living relative of the endosymbionts of termite gut flagellates and thereby provides an excellent model for studying the evolutionary processes during the establishment of an intracellular symbiosis. PMID:26184928

  9. The soil flagellate Proleptomonas faecicola: cell organisation and phylogeny suggest that the only described free-living trypanosomatid is not a kinetoplastid but has cercomonad affinities.

    PubMed

    Vickerman, Keith; Le Ray, Dominique; Hoef-Emden, Kerstin; De Jonckheere, Johan

    2002-03-01

    The only putative free-living trypanosomatid is Proleptomonas faecicola described first by Woodcock in 1916 as a coprophilic flagellate with striking Leptomonas-like flagellar movement but lacking a kinetoplast. P faecicola was later identified by Sandon in 1927 as a widespread non-phagotrophic inhabitant of soils. No division stages were seen by either observer. An organism conforming to Woodcock's light microscope description has been isolated from tapwater and cultivated axenically in various serum-containing media. Division has been shown to occur in an aflagellate stage enclosed in a thin cyst wall. Electron microscopy of the flagellate stage reveals that, in addition to the long locomotory flagellum, a second non-motile flagellum is present attached to the body along its entire length. The flagellate's ultrastructure lacks all the major features of the Trypanosomatidae. The several mitochondria of Proleptomonas have tubular cristae and lie between intracytoplasmic microtubules originating as a loose cone associated with the flagellar basal bodies. This cytoskeleton is much reduced in the division cyst. A comparable Proleptomonas-like flagellate with similar division cysts has been observed in soil samples from farmland. Phylogenetic analysis based on SSU rRNA gene sequences suggests that the cultured organism identified here as Proleptomonas is unrelated to the Kinetoplastida and has affinities with the Phylum Cercozoa Cavalier-Smith, even though in morphology, life cycle and mode of feeding it bears little resemblance to any member of that diverse grouping. PMID:12022280

  10. Interventional procedure based on nanorobots propelled and steered by flagellated magnetotactic bacteria for direct targeting of tumors in the human body.

    PubMed

    Martel, Sylvain; Felfoul, Ouajdi; Mohammadi, Mahmood; Mathieu, Jean-Baptiste

    2008-01-01

    Flagellated bacteria used as bio-actuators may prove to be efficient propulsion mechanisms for future hybrid medical nanorobots when operating in the microvasculature. Here, we briefly describe a medical interventional procedure where flagellated bacteria and more specifically MC-1 Magnetotactic Bacteria (MTB) can be used to propel and steer micro-devices and nanorobots under computer control to reach remote locations in the human body. In particular, we show through experimental results the potential of using MTB-tagged robots to deliver therapeutic agents to tumors even the ones located in deep regions of the human body. We also show that such bacterial nanorobots can be tracked inside the human body for enhanced targeting under computer guidance using MRI as imaging modality. MTB can not only be guided and controlled directly towards a specific target, but we also show experimentally that these flagellated bacterial nanorobots can be propelled and steered in vivo deeply through the interstitial region of a tumor. The targeting efficacy is increased when combined with larger ferromagnetic micro-carriers being propelled by magnetic gradients generated by a MRI platform to carry and release nanorobots propelled by a single flagellated bacterium near the arteriocapillar entry. Based on the experimental data obtained and the experience gathered during several experiments conducted in vivo with this new approach, a general medical interventional procedure is briefly described here in a biomedical engineering context. PMID:19163210

  11. Flagellated Magnetotactic Bacteria as Controlled MRI-trackable Propulsion and Steering Systems for Medical Nanorobots Operating in the Human Microvasculature

    PubMed Central

    Martel, Sylvain; Mohammadi, Mahmood; Felfoul, Ouajdi; Lu, Zhao; Pouponneau, Pierre

    2009-01-01

    Although nanorobots may play critical roles for many applications in the human body such as targeting tumoral lesions for therapeutic purposes, miniaturization of the power source with an effective onboard controllable propulsion and steering system have prevented the implementation of such mobile robots. Here, we show that the flagellated nanomotors combined with the nanometer-sized magnetosomes of a single Magnetotactic Bacterium (MTB) can be used as an effective integrated propulsion and steering system for devices such as nanorobots designed for targeting locations only accessible through the smallest capillaries in humans while being visible for tracking and monitoring purposes using modern medical imaging modalities such as Magnetic Resonance Imaging (MRI). Through directional and magnetic field intensities, the displacement speeds, directions, and behaviors of swarms of these bacterial actuators can be controlled from an external computer. PMID:19890435

  12. Use of monoclonal antibodies to distinguish pathogenic Naegleria fowleri (cysts, trophozoites, or flagellate forms) from other Naegleria species.

    PubMed Central

    Sparagano, O; Drouet, E; Brebant, R; Manet, E; Denoyel, G A; Pernin, P

    1993-01-01

    Monoclonal antibodies (MAbs) reactive to the pathogenic amoeba Naegleria fowleri were analyzed by enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay, Western blotting (immunoblotting), and radioimmunoprecipitation assay (RIPA). Two MAbs (3A4 and 5D12) showed reactivity by ELISA with all N. fowleri strains tested and no reactivity with the five other Naegleria species, N. lovaniensis, N. gruberi, N. australiensis, N. jadini, and N. andersoni. These MAbs reacted with the three morphological forms of N. fowleri (trophozoites, cysts, and flagellates). The reactivity on Western blots was suppressed by treatment with metaperiodate, suggesting a carbohydrate epitope. Differences in reactivity patterns between trophozoites and cysts observed with radioimmunoprecipitation assay might reflect differences in biological properties. The formalin stability of the epitope may be useful in detecting N. fowleri in fixed biopsies and in investigating the pathological process. Images PMID:8253977

  13. A mesocosm study of the changes in marine flagellate and ciliate communities in a crude oil bioremediation trial.

    PubMed

    Gertler, Christoph; Näther, Daniela J; Gerdts, Gunnar; Malpass, Mark C; Golyshin, Peter N

    2010-07-01

    Protozoan grazers play an important role in controlling the density of crude-oil degrading marine communities as has been evidenced in a number of microcosm experiments. However, small bioreactors contain a low initial titre of protozoa and the growth of hydrocarbon-depleting bacteria is accompanied by the fast depletion of mineral nutrients and oxygen, which makes microcosms rather unsuitable for simulating the sequence of events after the oil spill in natural seawater environment. In the present study, the population dynamics of marine protozoan community have been analysed in a 500 l mesocosm experiment involving bioaugmented oil booms that contained oil sorbents and slow-release fertilisers. A significant increase in numbers of marine flagellates and ciliates on biofilms of oil-degrading microbes was microscopically observed as early as 8 days after the start of the experiment, when protozoa exhibited a population density peak making up to 3,000 cells ml(-1). Further, the protozoan density varied throughout the experiment, but never dropped below 80 cells ml(-1). An 18S rRNA gene-based fingerprinting analysis revealed several changes within the eukaryotic community over the whole course of the experiment. Initial growth of flagellates and small ciliates was followed by a predominance of larger protozoa. According to microscopic observations and SSU rRNA molecular analyses, most predominant were the ciliates belonging to Euplotidae and Scuticociliatia. This is the first study to characterise the eukaryotic communities specifically in a large-scale oil bioremediation trial using both microscopy-based and several molecular techniques. PMID:20393846

  14. Growth-related gene product {alpha}: A chemotactic cytokine for neutrophils in rheumatoid arthritis

    SciTech Connect

    Koch, A.E.; Pope, R.M. |; Shah, M.R.; Hosaka, S.

    1995-10-01

    Leukocyte recruitment is critical in the inflammation seen in rheumatoid arthritis (RA). To determine whether the chemokine growth-related gene product {alpha} (gro{alpha}) plays a role in this process, we examined synovial tissue (ST), synovial fluid (SF), and plasma samples from 102 patients with arthritis. RA SF contained more antigenic gro{alpha} (mean 5.3 {+-} 1.9 ng/ml) than did SFs from either osteoarthritis (OA) or other forms of arthritis (mean 0.1 ng/ml) (p < 0.05). RA plasma contained more gro{alpha} (mean 4.3 {+-} 1.8 ng/ml) than normal plasma (mean 0.1 ng/ml) (p < 0.05). RA ST fibroblasts (1.2 x 10{sup 5}/cells/ml RPMI 1640/24 h) produced antigenic gro{alpha} (mean 0.2 {+-} 0.1 ng/ml), and this production was increased significantly upon incubation with TNF-{alpha} (mean 1.3 {+-} 0.3 ng/ml) or IL-1{beta} (mean 2.3 {+-} 0.6 ng/ml) (p < 0.05). Cells from RA SF also produced gro{alpha}: neutrophils (PMNs) (10{sup 7} cells/ml/24 h) produced 3.7 {+-} 0.7 ng/ml. RA SF mononuclear cells produced gro{alpha}, particularly upon incubation with LPS or PHA. Immunoreactive ST gro{alpha} was found in greater numbers of RA compared with either OA or normal lining cells, as well as in RA compared with OA subsynovial macrophages (p < 0.05). IL-8 accounted for a mean of 36% of the RA SF chemotactic activity for PMNs, while epithelial neutrophil-activating peptide-78 accounted for 34%, and gro{alpha} for 28%, of this activity. Combined neutralization of all three chemokines in RA SFs resulted in a mean decrease of 50% of the chemotactic activity for PMNs present in the RA SFs. These results indicate that gro{alpha} plays an important role in the ingress of PMNs into the RA joint. 54 refs., 6 figs., 1 tab.

  15. Accumulation of natural killer cells in ischemic brain tissues and the chemotactic effect of IP-10

    PubMed Central

    2014-01-01

    Background Stroke is accompanied by a distinguished inflammatory reaction that is initiated by the infiltration of immunocytes, expression of cytokines, and other inflammatory mediators. As natural killer cells (NK cells) are a type of cytotoxic lymphocyte critical to the innate immune system, we investigated the mechanism of NK cells-induced brain injuries after cerebral ischemia and the chemotactic effect of IP-10 simultaneously. Methods NK cells infiltration, interferon-gamma (IFN-γ) and IP-10 expression were detected by immunohistochemistry, immunofluorescence, PCR and flow cytometry in human and C57/BL6 wild type mouse ischemic brain tissues. The ischemia area was detected via 2,3,5-triphenyltetrazolium chloride staining. CXCR3 mean fluorescence intensity of isolated NK cells was measured by flow cytometry. The neuronal injury made by NK cells was examined via apoptosis experiment. The chemotactic of IP-10 was detected by migration and permeability assays. Results In human ischemic brain tissue, infiltrations of NK cells were observed and reached a peak at 2 to 5 days. In a permanent middle cerebral artery occlusion (pMCAO) model, infiltration of NK cells into the ischemic infarct region reached their highest levels 12 hours after ischemia. IFN-γ-positive NK cells and levels of the chemokine IP-10 were also detected within the ischemic region, from 6 hours up to 4 days after pMCAO was performed, and IFN-γ levels decreased after NK cells depletion in vivo. Co-culture experiments of neural cells with NK cells also showed that neural necrosis was induced via IFN-γ. In parallel experiments with IP-10, the presence of CXCR3 indicates that NK cells were affected by IP-10 via CXCR3, and the effect was dose-dependent. After IP-10 depletion in vivo, NK cells decreased. In migration assays and permeability experiments, disintegration of the blood–brain barrier (BBB) was observed following the addition of NK cells. Moreover, in the presence of IP-10 this injury

  16. Decreased numbers of chemotactic factor receptors in chronic neutropenia with defective chemotaxis: spontaneous recovery from the neutrophil abnormalities during early childhood

    SciTech Connect

    Yasui, K.; Yamazaki, M.; Miyagawa, Y.; Komiyama, A.; Akabane, T.

    1987-05-01

    Childhood chronic neutropenia with decreased numbers of chemotactic factor receptors as well as defective chemotaxis was first demonstrated in an 8-month-old girl. Chemotactic factor receptors on neutrophils were assayed using tritiated N-formyl-methionyl-leucyl-phenylalanine (/sup 3/H-FMLP). The patient's neutrophils had decreased numbers of the receptors: numbers of the receptors were 20,000 (less than 3 SD) as compared with those of control cells of 52,000 +/- 6000 (mean +/- SD) (n = 10). The neutropenia disappeared spontaneously by 28 months of age parallel with the improvement of chemotaxis and increase in numbers of chemotactic factor receptors. These results demonstrate a transient decrease of neutrophil chemotactic factor receptors as one of the pathophysiological bases of a transient defect of neutrophil chemotaxis in this disorder.

  17. Modification of β-Defensin-2 by Dicarbonyls Methylglyoxal and Glyoxal Inhibits Antibacterial and Chemotactic Function In Vitro

    PubMed Central

    Kiselar, Janna G.; Wang, Xiaowei; Dubyak, George R.; El Sanadi, Caroline; Ghosh, Santosh K.; Lundberg, Kathleen; Williams, Wesley M.

    2015-01-01

    Background Beta-defensins (hBDs) provide antimicrobial and chemotactic defense against bacterial, viral and fungal infections. Human β-defensin-2 (hBD-2) acts against gram-negative bacteria and chemoattracts immature dendritic cells, thus regulating innate and adaptive immunity. Immunosuppression due to hyperglycemia underlies chronic infection in Type 2 diabetes. Hyperglycemia also elevates production of dicarbonyls methylgloxal (MGO) and glyoxal (GO). Methods The effect of dicarbonyl on defensin peptide structure was tested by exposing recombinant hBD-2 (rhBD-2) to MGO or GO with subsequent analysis by MALDI-TOF MS and LC/MS/MS. Antimicrobial function of untreated rhBD-2 vs. rhBD-2 exposed to dicarbonyl against strains of both gram-negative and gram-positive bacteria in culture was determined by radial diffusion assay. The effect of dicarbonyl on rhBD-2 chemotactic function was determined by chemotaxis assay in CEM-SS cells. Results MGO or GO in vitro irreversibly adducts to the rhBD-2 peptide, and significantly reduces antimicrobial and chemotactic functions. Adducts derive from two arginine residues, Arg22 and Arg23 near the C-terminus, and the N-terminal glycine (Gly1). We show by radial diffusion testing on gram-negative E. coli and P. aeruginosa, and gram-positive S. aureus, and a chemotaxis assay for CEM-SS cells, that antimicrobial activity and chemotactic function of rhBD-2 are significantly reduced by MGO. Conclusions Dicarbonyl modification of cationic antimicrobial peptides represents a potential link between hyperglycemia and the clinical manifestation of increased susceptibility to infection, protracted wound healing, and chronic inflammation in undiagnosed and uncontrolled Type 2 diabetes. PMID:26244639

  18. A Worldwide Competition to Compare the Speed and Chemotactic Accuracy of Neutrophil-Like Cells

    PubMed Central

    Wong, Elisabeth; Hamza, Bashar; Bae, Albert; Martel, Joseph; Kataria, Rama; Keizer-Gunnink, Ineke; Kortholt, Arjan; Van Haastert, Peter J. M.; Charras, Guillaume; Janetopoulos, Christopher; Irimia, Daniel

    2016-01-01

    Chemotaxis is the ability to migrate towards the source of chemical gradients. It underlies the ability of neutrophils and other immune cells to hone in on their targets and defend against invading pathogens. Given the importance of neutrophil migration to health and disease, it is crucial to understand the basic mechanisms controlling chemotaxis so that strategies can be developed to modulate cell migration in clinical settings. Because of the complexity of human genetics, Dictyostelium and HL60 cells have long served as models system for studying chemotaxis. Since many of our current insights into chemotaxis have been gained from these two model systems, we decided to compare them side by side in a set of winner-take-all races, the Dicty World Races. These worldwide competitions challenge researchers to genetically engineer and pharmacologically enhance the model systems to compete in microfluidic racecourses. These races bring together technological innovations in genetic engineering and precision measurement of cell motility. Fourteen teams participated in the inaugural Dicty World Race 2014 and contributed cell lines, which they tuned for enhanced speed and chemotactic accuracy. The race enabled large-scale analyses of chemotaxis in complex environments and revealed an intriguing balance of speed and accuracy of the model cell lines. The successes of the first race validated the concept of using fun-spirited competition to gain insights into the complex mechanisms controlling chemotaxis, while the challenges of the first race will guide further technological development and planning of future events. PMID:27332963

  19. Increased expression of monocyte chemotactic protein-1 during active hepatic fibrogenesis: correlation with monocyte infiltration.

    PubMed Central

    Marra, F.; DeFranco, R.; Grappone, C.; Milani, S.; Pastacaldi, S.; Pinzani, M.; Romanelli, R. G.; Laffi, G.; Gentilini, P.

    1998-01-01

    Monocyte chemotactic protein (MCP)-1 is a chemoattractant and activator for circulating monocytes and T lymphocytes. We investigated MCP-1 protein and gene expression during chronic liver disease at different stages, using immunohistochemistry and in situ hybridization, respectively. In normal liver, a modest expression of MCP-1 was confined to few peri-sinusoidal cells and to bile duct epithelial cells. During chronic hepatitis, MCP-1 immunostaining and gene expression were evident in the inflammatory infiltrate of the portal tract. In tissue from patients with active cirrhosis, MCP-1 expression was clearly up-regulated and was present in the portal tract, in the epithelial cells of regenerating bile ducts, and in the active septa surrounding regenerating nodules. A combination of in situ hybridization for MCP-1 and immunohistochemistry showed that activated stellate cells and monocyte/macrophages contribute to MCP-1 expression in vivo together with bile duct epithelial cells. Comparison of serial sections of liver biopsies from patients with various degrees of necro-inflammatory activity showed that infiltration of the portal tracts with monocytes/macrophages is directly correlated with the expression of MCP-1. These data expand previous in vitro studies showing that secretion of MCP-1 may contribute to the formation and maintenance of the inflammatory infiltrate observed during chronic liver disease. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:9466568

  20. Ca2+ spikes in the flagellum control chemotactic behavior of sperm

    PubMed Central

    Böhmer, Martin; Van, Qui; Weyand, Ingo; Hagen, Volker; Beyermann, Michael; Matsumoto, Midori; Hoshi, Motonori; Hildebrand, Eilo; Kaupp, Ulrich Benjamin

    2005-01-01

    The events that occur during chemotaxis of sperm are only partly known. As an essential step toward determining the underlying mechanism, we have recorded Ca2+ dynamics in swimming sperm of marine invertebrates. Stimulation of the sea urchin Arbacia punctulata by the chemoattractant or by intracellular cGMP evokes Ca2+ spikes in the flagellum. A Ca2+ spike elicits a turn in the trajectory followed by a period of straight swimming (‘turn-and-run'). The train of Ca2+ spikes gives rise to repetitive loop-like movements. When sperm swim in a concentration gradient of the attractant, the Ca2+ spikes and the stimulus function are synchronized, suggesting that precise timing of Ca2+ spikes controls navigation. We identified the peptide asterosap as a chemotactic factor of the starfish Asterias amurensis. The Ca2+ spikes and swimming behavior of sperm from starfish and sea urchin are similar, implying that the signaling pathway of chemotaxis has been conserved for almost 500 million years. PMID:16001082

  1. Ca2+ spikes in the flagellum control chemotactic behavior of sperm.

    PubMed

    Böhmer, Martin; Van, Qui; Weyand, Ingo; Hagen, Volker; Beyermann, Michael; Matsumoto, Midori; Hoshi, Motonori; Hildebrand, Eilo; Kaupp, Ulrich Benjamin

    2005-08-01

    The events that occur during chemotaxis of sperm are only partly known. As an essential step toward determining the underlying mechanism, we have recorded Ca2+ dynamics in swimming sperm of marine invertebrates. Stimulation of the sea urchin Arbacia punctulata by the chemoattractant or by intracellular cGMP evokes Ca2+ spikes in the flagellum. A Ca2+ spike elicits a turn in the trajectory followed by a period of straight swimming ('turn-and-run'). The train of Ca2+ spikes gives rise to repetitive loop-like movements. When sperm swim in a concentration gradient of the attractant, the Ca2+ spikes and the stimulus function are synchronized, suggesting that precise timing of Ca2+ spikes controls navigation. We identified the peptide asterosap as a chemotactic factor of the starfish Asterias amurensis. The Ca2+ spikes and swimming behavior of sperm from starfish and sea urchin are similar, implying that the signaling pathway of chemotaxis has been conserved for almost 500 million years. PMID:16001082

  2. Relation of Chemotactic Response to the Amount of Receptor: Evidence for Different Efficiencies of Signal Transduction

    PubMed Central

    Koman, Ahmet; Harayama, Shigeaki; Hazelbauer, Gerald L.

    1979-01-01

    We determined the content of galactose-glucose-, maltose-, and ribose-binding proteins in cells of Escherichia coli K-12 grown in a variety of media and also measured the respective transport and chemotactic activities that depend on those binding proteins. Correlation of the level of induction of a particular binding protein with the extent of tactic activity mediated by that protein indicates that the magnitude of the tactic response to a particular stimulating compound is a direct function of the number of receptors per cell. In contrast, comparison of the magnitudes of response to substances recognized by independent receptors indicates that some stimulus-receptor complexes are more effective in eliciting tactic responses than are others. Thus, the magnitude of response to any particular stimulating compound is a function both of the number of receptors per cell and of the effectiveness of the stimulus-receptor complex. Considerations of available information about the tactic response to maltose suggest that the effectiveness of a stimulus-receptor complex is related to the transducer with which the receptor interacts. The tar product appears to be a relatively effective transducer of the signals it accepts from receptors for aspartate, α-methylaspartate, and maltose, whereas the trg product appears to be a relatively ineffective transducer of signals it accepts from receptors for galactose and ribose. Images PMID:378935

  3. Enhancement of Chemotactic Cell Aggregation by Haptotactic Cell-To-Cell Interaction.

    PubMed

    Kwon, Tae-Goo; Yang, Taeseok Daniel; Lee, Kyoung J

    2016-01-01

    The crawling of biological cell is a complex phenomenon involving various biochemical and mechanical processes. Some of these processes are intrinsic to individual cells, while others pertain to cell-to-cell interactions and to their responses to extrinsically imposed cues. Here, we report an interesting aggregation dynamics of mathematical model cells, when they perform chemotaxis in response to an externally imposed global chemical gradient while they influence each other through a haptotaxis-mediated social interaction, which confers intriguing trail patterns. In the absence of the cell-to-cell interaction, the equilibrium population density profile fits well to that of a simple Keller-Segal population dynamic model, in which a chemotactic current density [Formula: see text] competes with a normal diffusive current density [Formula: see text], where p and ρ refer to the concentration of chemoattractant and population density, respectively. We find that the cell-to-cell interaction confers a far more compact aggregation resulting in a much higher peak equilibrium cell density. The mathematical model system is applicable to many biological systems such as swarming microglia and neutrophils or accumulating ants towards a localized food source. PMID:27128310

  4. The actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations

    NASA Astrophysics Data System (ADS)

    Westendorf, Christian; Negrete, Jose, Jr.; Bae, Albert; Sandmann, Rabea; Bodenschatz, Eberhard; Beta, Carsten

    2013-03-01

    We report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. The averaged F-actin response of many cells to a short-time pulse of cAMP is reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. We systematically exposed a large number of cells to periodic pulse trains. The results indicate a resonance peak at periodic inputs of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the actin regulatory network. To quantitatively test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and Aip1. These served as markers of the F-actin disassembly process and thus allow us to estimate the delay time. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed experimentally. Financial support by the Max-Planck Society and the DFG (SFB 937).

  5. A Worldwide Competition to Compare the Speed and Chemotactic Accuracy of Neutrophil-Like Cells.

    PubMed

    Skoge, Monica; Wong, Elisabeth; Hamza, Bashar; Bae, Albert; Martel, Joseph; Kataria, Rama; Keizer-Gunnink, Ineke; Kortholt, Arjan; Van Haastert, Peter J M; Charras, Guillaume; Janetopoulos, Christopher; Irimia, Daniel

    2016-01-01

    Chemotaxis is the ability to migrate towards the source of chemical gradients. It underlies the ability of neutrophils and other immune cells to hone in on their targets and defend against invading pathogens. Given the importance of neutrophil migration to health and disease, it is crucial to understand the basic mechanisms controlling chemotaxis so that strategies can be developed to modulate cell migration in clinical settings. Because of the complexity of human genetics, Dictyostelium and HL60 cells have long served as models system for studying chemotaxis. Since many of our current insights into chemotaxis have been gained from these two model systems, we decided to compare them side by side in a set of winner-take-all races, the Dicty World Races. These worldwide competitions challenge researchers to genetically engineer and pharmacologically enhance the model systems to compete in microfluidic racecourses. These races bring together technological innovations in genetic engineering and precision measurement of cell motility. Fourteen teams participated in the inaugural Dicty World Race 2014 and contributed cell lines, which they tuned for enhanced speed and chemotactic accuracy. The race enabled large-scale analyses of chemotaxis in complex environments and revealed an intriguing balance of speed and accuracy of the model cell lines. The successes of the first race validated the concept of using fun-spirited competition to gain insights into the complex mechanisms controlling chemotaxis, while the challenges of the first race will guide further technological development and planning of future events. PMID:27332963

  6. Enhancement of Chemotactic Cell Aggregation by Haptotactic Cell-To-Cell Interaction

    PubMed Central

    Kwon, Tae-goo; Yang, Taeseok Daniel; Lee, Kyoung J.

    2016-01-01

    The crawling of biological cell is a complex phenomenon involving various biochemical and mechanical processes. Some of these processes are intrinsic to individual cells, while others pertain to cell-to-cell interactions and to their responses to extrinsically imposed cues. Here, we report an interesting aggregation dynamics of mathematical model cells, when they perform chemotaxis in response to an externally imposed global chemical gradient while they influence each other through a haptotaxis-mediated social interaction, which confers intriguing trail patterns. In the absence of the cell-to-cell interaction, the equilibrium population density profile fits well to that of a simple Keller-Segal population dynamic model, in which a chemotactic current density J→chemo∼∇p competes with a normal diffusive current density J→diff∼∇ρ, where p and ρ refer to the concentration of chemoattractant and population density, respectively. We find that the cell-to-cell interaction confers a far more compact aggregation resulting in a much higher peak equilibrium cell density. The mathematical model system is applicable to many biological systems such as swarming microglia and neutrophils or accumulating ants towards a localized food source. PMID:27128310

  7. Marangoni-driven chemotaxis, chemotactic collapse, and the Keller-Segel equation

    NASA Astrophysics Data System (ADS)

    Shelley, Michael; Masoud, Hassan

    2013-11-01

    Almost by definition, chemotaxis involves the biased motion of motile particles along gradients of a chemical concentration field. Perhaps the most famous model for collective chemotaxis in mathematical biology is the Keller-Segel model, conceived to describe collective aggregation of slime mold colonies in response to an intrinsically produced, and diffusing, chemo-attractant. Heavily studied, particularly in 2D where the system is ``super-critical'', it has been proved that the KS model can develop finite-time singularities - so-called chemotactic collapse - of delta-function type. Here, we study the collective dynamics of immotile particles bound to a 2D interface above a 3D fluid. These particles are chemically active and produce a diffusing field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. Remarkably, we show that this system involving 3D diffusion and fluid dynamics, exactly yields the 2D Keller-Segel model for the surface-flow of active particles. We discuss the consequences of collapse on the 3D fluid dynamics, and generalizations of the fluid-dynamical model.

  8. Neutrophil chemotactic factor release and neutrophil alveolitis in asbestos-exposed individuals

    SciTech Connect

    Hayes, A.A.; Rose, A.H.; Musk, A.W.; Robinson, B.W.

    1988-09-01

    Alveolar neutrophil accumulation occurs in asbestosis. To evaluate a possible role for release of neutrophil chemotactic factor (NCF) in the pathogenesis of asbestosis, spontaneous NCF release from alveolar macrophages obtained by bronchoalveolar lavage (BAL) in eight individuals with asbestosis, 13 asbestos-exposed individuals without asbestosis, and five control subjects has been studied. Alveolar macrophages were incubated in medium (four hours; 37 degrees C), and neutrophil responses to the supernatants were assayed in a microchemotaxis chamber. Alveolar macrophages from subjects with asbestosis released more NCF (97 +/- 19 neutrophils per high-power field (N/HPF)) than controls (3 +/- 1 N/HPF; p less than 0.01). Alveolar macrophages from individuals with asbestos exposure and increased BAL neutrophil proportions (n = 7) released more NCF (93 +/- 24 N/HPF) than individuals with asbestos exposure and normal BAL neutrophil proportions (n = 6; 11 +/- 6 N/HPF; p less than 0.02). The results show that spontaneous NCF release occurs in asbestosis and that NCF release is associated with neutrophil alveolitis in asbestos-exposed individuals without asbestosis, suggesting a pathogenic role for NCF in mediating this neutrophil alveolitis. The results of the study also suggest that the presence of crackles is a better predictor of the presence of neutrophil alveolitis than is an abnormal chest x-ray film.

  9. Leukocyte chemotactic factor 2 amyloidosis (ALECT2) is a common form of renal amyloidosis among Egyptians.

    PubMed

    Larsen, Christopher P; Ismail, Wesam; Kurtin, Paul J; Vrana, Julie A; Dasari, Surendra; Nasr, Samih H

    2016-04-01

    Large case series of renal amyloidosis subtypes have recently been published in the United States and Europe showing AL amyloidosis to be the predominant subtype in this part of the world. However, the most common subtypes of renal amyloidosis throughout the rest of the world are unknown. We present here the first large case series detailing the subtypes of renal amyloidosis among Egyptians. In this population, AA amyloidosis was the most common type of amyloidosis on renal biopsy at 48%. The newly described leukocyte chemotactic factor 2 amyloidosis (ALECT2) was the second most common type and represented nearly one-third of renal amyloid cases at 31%. AL accounted for only 20% of cases. The pathologic findings in ALECT2 cases were similar to those previously described in other case series. Thus ALECT2, which was initially thought to affect mainly Hispanics in the United States, appears to represent an important and likely underrecognized etiology of chronic kidney disease among Egyptians and probably in other ethnic groups around the world. PMID:26867784

  10. Emerging morphologies in round bacterial colonies: comparing volumetric versus chemotactic expansion.

    PubMed

    Giverso, Chiara; Verani, Marco; Ciarletta, Pasquale

    2016-06-01

    Biological experiments performed on living bacterial colonies have demonstrated the microbial capability to develop finger-like shapes and highly irregular contours, even starting from an homogeneous inoculum. In this work, we study from the continuum mechanics viewpoint the emergence of such branched morphologies in an initially circular colony expanding on the top of a Petri dish coated with agar. The bacterial colony expansion, based on either a source term, representing volumetric mitotic processes, or a nonconvective mass flux, describing chemotactic expansion, is modeled at the continuum scale. We demonstrate that the front of the colony is always linearly unstable, having similar dispersion curves to the ones characterizing branching instabilities. We also perform finite element simulations, which not only prove the emergence of branching, but also highlight dramatic differences between the two mechanisms of colony expansion in the nonlinear regime. Furthermore, the proposed combination of analytical and numerical analysis allowed studying the influence of different model parameters on the selection of specific patterns. A very good agreement has been found between the resulting simulations and the typical structures observed in biological assays. Finally, this work provides a new interpretation of the emergence of branched patterns in living aggregates, depicted as the results of a complex interplay among chemical, mechanical and size effects. PMID:26296713

  11. Influence of corticosteroids on chemotactic response and collagen metabolism of human skin fibroblasts.

    PubMed

    Hein, R; Mauch, C; Hatamochi, A; Krieg, T

    1988-07-15

    Following chronic administration of corticosteroids in vivo, a number of complications occur, which mainly involve the metabolism of connective tissue cells. Therefore, several attempts have been made to develop corticosteroids, which show less pronounced side effects. Fibroblasts were kept in monolayer cultures and were exposed to corticosteroids demonstrating similar anti-inflammatory activity (prednicarbate, desoximetasone). Chemotaxis of fibroblasts was studied over 4 hr, protein and collagen synthesis were estimated using proteinchemical methods and also by dot blot hybridization. Corticosteroids used in a high dosage (10 microM) affected all biosynthetic capacities of the investigated fibroblasts. Protein synthesis and production of collagen types I and III were reduced and a similar decrease of mRNA levels for collagen type I could be found indicating an influence on the pretranslational control. In the same concentrations desoximetasone was much more active than prednicarbate. Fibroblast migration was dosage dependently inhibited from 10(-9) M to 10(-5) M for desoximetasone, while incubation with prednicarbate did not cause a reduction of the chemotactic response at concentrations lower than 10(-7) M. These data suggest that modifications of corticosteroids might result in a dissociation of some of their biological activities and can specifically influence their effects on biosynthetic capacities of fibroblasts. PMID:3395353

  12. Characterization of the chemotactic and mitogenic response of SMCs to PDGF-BB and FGF-2 in fibrin hydrogels

    PubMed Central

    Ucuzian, Areck A.; Brewster, Luke P.; East, Andrea T.; Pang, Yongang; Gassman, Andrew A.; Greisler, Howard P.

    2010-01-01

    The delivery of growth factors to cellularize biocompatible scaffolds like fibrin is a commonly used strategy in tissue engineering. We characterized SMC proliferation and chemotaxis in response to PDGF-BB and FGF-2, alone and in combination, in 2-D culture and in 3-D fibrin hydrogels. While both growth factors induced an equipotent mitogenic response in 2-D culture, only FGF-2 was significantly mitogenic for SMCs in 3-D culture. Only PDGF-BB was significantly chemotactic in a modified Boyden chamber assay. In a 3-D assay of matrix invasion, both growth factors induced an invasive response into the fibrin hydrogel in both proliferating and non-proliferating, mitomycin C (MMC) treated cells. The invasive response was less attenuated by the inhibition of proliferation in PDGF-BB stimulated cells compared with FGF-2 stimulated cells. We conclude that SMCs cultured in fibrin hydrogels have a more robust chemotactic response to PDGF-BB compared with FGF-2, and that the response to FGF-2 is more dependent on cell proliferation. Delivery of both growth factors together potentiates the chemotactic, but not mitogenic response to either growth factor alone. PMID:20730936

  13. Plant-Adapted Escherichia coli Show Increased Lettuce Colonizing Ability, Resistance to Oxidative Stress and Chemotactic Response

    PubMed Central

    Dublan, Maria de los Angeles; Ortiz-Marquez, Juan Cesar Federico; Lett, Lina; Curatti, Leonardo

    2014-01-01

    Background Escherichia coli is a widespread gut commensal and often a versatile pathogen of public health concern. E. coli are also frequently found in different environments and/or alternative secondary hosts, such as plant tissues. The lifestyle of E. coli in plants is poorly understood and has potential implications for food safety. Methods/Principal Findings This work shows that a human commensal strain of E. coli K12 readily colonizes lettuce seedlings and produces large microcolony-like cell aggregates in leaves, especially in young leaves, in proximity to the vascular tissue. Our observations strongly suggest that those cell aggregates arise from multiplication of single bacterial cells that reach those spots. We showed that E. coli isolated from colonized leaves progressively colonize lettuce seedlings to higher titers, suggesting a fast adaptation process. E. coli cells isolated from leaves presented a dramatic rise in tolerance to oxidative stress and became more chemotactic responsive towards lettuce leaf extracts. Mutant strains impaired in their chemotactic response were less efficient lettuce colonizers than the chemotactic isogenic strain. However, acclimation to oxidative stress and/or minimal medium alone failed to prime E. coli cells for enhanced lettuce colonization efficiency. Conclusion/Significance These findings help to understand the physiological adaptation during the alternative lifestyle of E. coli in/on plant tissues. PMID:25313845

  14. Effect of vasoactive peptides in Tetrahymena: chemotactic activities of adrenomedullin, proadrenomedullin N-terminal 20 peptide (PAMP) and calcitonin gene-related peptide (CGRP).

    PubMed

    Kőhidai, László; Tóth, Katalin; Samotik, Paul; Ranganathan, Kiran; Láng, Orsolya; Tóth, Miklós; Ruskoaho, Heikki

    2016-01-01

    Adrenomedullin (AMD), proadrenomedullin N-terminal 20 peptide (PAMP) and calcitonin gene-related peptide (CGRP) were studied for chemotaxis, chemotactic selection and G-actin/F-actin transition in Tetrahymena. The aim of the experiments was to study the effects of two different peptides encoded by the same gene compared to a peptide related to one of the two, but encoded by a different gene, at a low level of phylogeny. The positive, chemotactic effect of ADM and the strong negative, chemorepellent effect of PAMP suggest that in Tetrahymena, the two peptides elicit their chemotactic effects via different signalling mechanisms. The complexity of swimming behaviour modulated by the three peptides underlines that chemotaxis, chemokinesis and some characteristics of migratory behaviour (velocity, tortuosity) are working as a sub-population level complex functional unit. Chemotactic responsiveness to ADM and CGRP is short-term, in contrast to PAMP, which as a chemorepellent ligand, has the ability to select sub-populations with negative chemotactic responsiveness. The different effects of ADM and PAMP on the polymerization of actin networks show that the microtubular structure of cilia is more essential to chemotactic response than are transitions of the actin network. The results draw attention to the characteristic effects of vasoactive peptides at this low level of phylogeny. PMID:26481478

  15. The amoeba-to-flagellate transformation test is not reliable for the diagnosis of the genus Naegleria. Description of three new Naegleria spp.

    PubMed

    De Jonckheere, J F; Brown, S; Dobson, P J; Robinson, B S; Pernin, P

    2001-07-01

    Trophozoites of several isolates from one location in Australia have failed consistently to transform into flagellates, although they display all other characteristics of the genus Naegleria. When changing the standard transformation test, flagellates were produced. In phylogenetic trees derived from partial small subunit ribosomal DNA (SSUrDNA) sequences, one of these strains branches close to a cluster comprising N. clarki, N. australiensis, N. italica and N. jadini. It is proposed that these Australian isolates represent a new species, named N. fultoni (strain NG885). Failing to form flagellates since their isolation, even when different transformation procedures are used, are two Naegleria strains from Chile and Indonesia. In SSUrDNA-based phylogenetic trees the Chilean strain clusters with N. pussardi and the Indonesian strain clusters with N. galeacystis, but the degree of sequence difference from these described species (3.5% and 2.2%, respectively) is sufficient to propose that both of the strains represent new species, named N. chilensis (strain NG946) and N. indonesiensis (strain NG945), respectively. The close relationships between each of the new species and the Naegleria species with which they cluster in SSUrDNA-based trees were confirmed by ribosomal internal transcribed spacer region (ITS) sequence comparisons. In France, several non-flagellating N. fowleri strains were isolated from one location. ITS rDNA sequence comparisons indicated that they correspond to a 'type' of N. fowleri found in both Europe and the USA. A redefinition of the genus Naegleria is proposed as a consequence of these and previous findings. PMID:11545434

  16. On Keelungia pulex nov. gen. et nov. sp., a heterotrophic euglenoid flagellate that lacks pellicular plates (Euglenophyceae, Euglenida).

    PubMed

    Chan, Ya-Fan; Moestrup, Øjvind; Chang, Jeng

    2013-01-01

    Keelungia pulex nov. gen. et nov. sp. is described from coastal waters of NE Taiwan. The new species is heterotrophic and feeds on bacteria. Cells are oblong-ovoid, biflagellate and glide along the sides of the flask. Each cell is approximately 8-11μm long, and one of the smallest euglenoid flagellates presently known. Keelungia lacks pellicular plates and in this respect resembles diplonemids and Symbiontida, which are thought to be among the basal groups of Euglenozoa. SEM showed the presence of 10 evenly spaced longitudinal striae in the cell surface, but the striae are difficult to see in the light microscope. TEM showed each stria to comprise a double set of very low longitudinal ridges separated by a shallow furrow, and supported by ca 5 microtubules beneath the plasmalemma, unlike the situation in diplonemids and Symbiontida. The cell surface was further subtended by an extensive system of rough cisternae of endoplasmic reticulum. Keelungia pulex is phylogenetically related to species of Ploeotia and to Lentomonas applanata, but differs in details of the feeding apparatus and in the absence of pellicular plates. Sequencing of SSU rDNA indicates that Ploeotia, Keelungia and Entosiphon form a clade near the base of the euglenoid phylogenetic tree. PMID:22698812

  17. Combined stress effect of pH and temperature narrows the niche width of flagellates in acid mining lakes

    PubMed Central

    Moser, Michael; Weisse, Thomas

    2011-01-01

    Strains of the green alga Chlamydomonas acidophila and two chrysomonads, Ochromonas spp., isolated from each of two similar acid mining lakes (AMLs) with extremely low pH (∼2.6) were investigated to consider a possible synergistic stress effect of low pH and unfavourable temperature. We measured flagellate growth rates over a combination of four pH (2.5, 3.5, 5.0 and 7.0) and three temperatures (10, 17.5 and 25°C) in the laboratory. Our hypothesis was that, under highly acidic conditions (pH <3), an obligate acidophil species (C. acidophila) would be less sensitive to the combined stress of pH and temperature than acidotolerant species (Ochromonas spp.). We expected that the difference of the fundamental vs. realized pH niche would be greater in the latter. Another chrysomonad, Poterioochromonas malhamensis strain DS, served as a reference for a closely related neutrophil species. Surprisingly, C. acidophila did not survive temperatures >27°C. The lowest temperature tested reduced growth rates of all three chrysomonad strains significantly. Since all chrysomonads were tolerant to high temperature, growth rate of one Ochromonas spp. strain was measured exemplarily at 35°C. Only at this high temperature was the realized pH niche significantly narrowed. We also recorded significant intraspecific differences within the C. acidophila strains from the two AML, illustrating that the niche width of a species is broader than that of individual clones. PMID:21655470

  18. Biogeography of Heterotrophic Flagellate Populations Indicates the Presence of Generalist and Specialist Taxa in the Arctic Ocean

    PubMed Central

    Thaler, Mary

    2015-01-01

    Heterotrophic marine flagellates (HF) are ubiquitous in the world's oceans and represented in nearly all branches of the domain Eukaryota. However, the factors determining distributions of major taxonomic groups are poorly known. The Arctic Ocean is a good model environment for examining the distribution of functionally similar but phylogenetically diverse HF because the physical oceanography and annual ice cycles result in distinct environments that could select for microbial communities or favor specific taxa. We reanalyzed new and previously published high-throughput sequencing data from multiple studies in the Arctic Ocean to identify broad patterns in the distribution of individual taxa. HF accounted for fewer than 2% to over one-half of the reads from the water column and for up to 60% of reads from ice, which was dominated by Cryothecomonas. In the water column, many HF phylotypes belonging to Telonemia and Picozoa, uncultured marine stramenopiles (MAST), and choanoflagellates were geographically widely distributed. However, for two groups in particular, Telonemia and Cryothecomonas, some species level taxa showed more restricted distributions. For example, several phylotypes of Telonemia favored open waters with lower nutrients such as the Canada Basin and offshore of the Mackenzie Shelf. In summary, we found that while some Arctic HF were successful over a range of conditions, others could be specialists that occur under particular conditions. We conclude that tracking species level diversity in HF not only is feasible but also provides a potential tool for understanding the responses of marine microbial ecosystems to rapidly changing ice regimes. PMID:25595764

  19. A rapid phenol toxicity test based on photosynthesis and movement of the freshwater flagellate, Euglena agilis Carter.

    PubMed

    Kottuparambil, Sreejith; Kim, Youn-Jung; Choi, Hoon; Kim, Mi-Sung; Park, Areum; Park, Jihae; Shin, Woongghi; Han, Taejun

    2014-10-01

    Phenol, a monosubstituted aromatic hydrocarbon with various commercial uses, is a major organic constituent in industrial wastewaters. The ecotoxic action of phenol for aquatic environment is well known. In this study, rapid phenol toxicity tests (1h) were developed based on chlorophyll a (Chl a) fluorescence and the movement parameters of the freshwater flagellate, Euglena agilis Carter. Phenol significantly reduced the maximum quantum yield (Fv/Fm) of photosystem II (PS II) and the maximum photosynthetic electron transport rate (rETRmax) with median effective concentration (EC50) values of 8.94 and 4.67 mM, respectively. Phenol reduced the motility and triggered change in the swimming velocity of the test organism. Among the parameters tested, velocity was the most sensitive biomarker with an EC50 of 3.17 mM. The EC50 values for Fv/Fm, motility, and velocity appear to overlap the permitted levels of phenol. In conclusion, the photosynthesis and movement of E. agilis can be fast and sensitive risk assessment parameters for the evaluation of phenol toxicity in municipal and industrial effluents. PMID:24953851

  20. Melanoma Cells Break Down LPA to Establish Local Gradients That Drive Chemotactic Dispersal

    PubMed Central

    Muinonen-Martin, Andrew J.; Susanto, Olivia; Zhang, Qifeng; Smethurst, Elizabeth; Faller, William J.; Veltman, Douwe M.; Kalna, Gabriela; Lindsay, Colin; Bennett, Dorothy C.; Sansom, Owen J.; Herd, Robert; Jones, Robert; Machesky, Laura M.; Wakelam, Michael J. O.; Knecht, David A.; Insall, Robert H.

    2014-01-01

    The high mortality of melanoma is caused by rapid spread of cancer cells, which occurs unusually early in tumour evolution. Unlike most solid tumours, thickness rather than cytological markers or differentiation is the best guide to metastatic potential. Multiple stimuli that drive melanoma cell migration have been described, but it is not clear which are responsible for invasion, nor if chemotactic gradients exist in real tumours. In a chamber-based assay for melanoma dispersal, we find that cells migrate efficiently away from one another, even in initially homogeneous medium. This dispersal is driven by positive chemotaxis rather than chemorepulsion or contact inhibition. The principal chemoattractant, unexpectedly active across all tumour stages, is the lipid agonist lysophosphatidic acid (LPA) acting through the LPA receptor LPAR1. LPA induces chemotaxis of remarkable accuracy, and is both necessary and sufficient for chemotaxis and invasion in 2-D and 3-D assays. Growth factors, often described as tumour attractants, cause negligible chemotaxis themselves, but potentiate chemotaxis to LPA. Cells rapidly break down LPA present at substantial levels in culture medium and normal skin to generate outward-facing gradients. We measure LPA gradients across the margins of melanomas in vivo, confirming the physiological importance of our results. We conclude that LPA chemotaxis provides a strong drive for melanoma cells to invade outwards. Cells create their own gradients by acting as a sink, breaking down locally present LPA, and thus forming a gradient that is low in the tumour and high in the surrounding areas. The key step is not acquisition of sensitivity to the chemoattractant, but rather the tumour growing to break down enough LPA to form a gradient. Thus the stimulus that drives cell dispersal is not the presence of LPA itself, but the self-generated, outward-directed gradient. PMID:25313567

  1. Localized expression of mRNA for phagocyte-specific chemotactic cytokines in human periodontal infections.

    PubMed Central

    Tonetti, M S; Imboden, M A; Gerber, L; Lang, N P; Laissue, J; Mueller, C

    1994-01-01

    In bacterial infections, mononuclear and polymorphonuclear phagocytes are key components of host defenses. Recent investigations have indicated that chemokines are able to recruit and activate phagocytes. In particular, interleukin-8 (IL-8) attracts polymorphonuclear leukocytes (PMNs), while monocyte chemoattractant protein-1 (MCP-1) is selective for cells of the monocyte/macrophage lineage. In this investigation, we analyzed the in situ expression of IL-8 and MCP-1 mRNAs in human periodontal infections. Specific mRNA was detected by in situ hybridization using 35S-labeled riboprobes in frozen tissue sections. Phagocytes (PMNs and macrophages) were specifically detected as elastase-positive or CD68+ cells by a three-stage immunoperoxidase technique. Results indicated that expression of phagocyte-specific cytokines was confined to selected tissue locations and, in general, paralleled phagocyte infiltration. In particular, IL-8 expression was maximal in the junctional epithelium adjacent to the infecting microorganisms; PMN infiltration was more prominent in the same area. MCP-1 was expressed in the chronic inflammatory infiltrate and along the basal layer of the oral epithelium. Cells of the monocyte/macrophage lineage were demonstrated to be present in the same areas. The observed expression pattern may be the most economic way to establish a cell-type-selective chemotactic gradient within the tissue that is able to effectively direct polymorphonuclear phagocyte migration toward the infecting microorganisms and modulate mononuclear phagocyte infiltration in the surrounding tissues. This process may optimize host defenses and contribute to containing leukocyte infiltration to the infected and inflamed area, thus limiting tissue damage. Images PMID:8063420

  2. Modulation of signalling in neutrophils activated by a chemotactic peptide: calcium regulates diacyl glycerol metabolism

    SciTech Connect

    Korchak, H.M.; Vosshall, L.B.; Lundquist, K.F.

    1987-05-01

    Neutrophils activated by ligands such as the chemotactic peptide f-Met-Leu-Phe (FMLP) generate superoxide anion (O/sub 2//sup -/) and release specific and azurophil granule contents. The signalling for this response is thought to involve both elevated cytosolic Ca and protein kinase C activity. Receptor-occupation triggers a phospholipase C to cleave phosphatidyl inositol 4,5 bisphosphate (PIP/sub 2/) yielding inositol 1,4,5 trisphosphate, (IP/sub 3/), a trigger for intracellular Ca release, and diacyl glycerol (DG), which together with Ca activates protein kinase C. The DG can be metabolized to phosphatidic acid (PA). FMLP triggered a rapid increase in cytosolic Ca (fura-2). Loading cells with MAPTAM, and intracellular Ca buffer, suppressed this Ca transient in FMLP activated cells and inhibited O/sub 2//sup -/ generation to 12.5% of control, beta-glucuronidase release to 40.3% of control and lysozyme release to 55.1% of control. FMLP triggered a prompt decrease in PIP/sub 2/ in cells pre-labelled with /sup 32/P or /sup 3/H-inositol and an increase in PA and release of /sup 3/H-IP/sub 3/. A rapid increase in /sup 14/C-DG levels was also observed in /sup 14/C-glycerol pre-loaded cells activated by FMLP. Suppression of the Ca transient by buffering with MAPTAM inhibited elevation of /sup 14/C-DG. Breakdown of PIP/sub 2/ was not inhibited and elevation of /sup 32/P-PA was enhanced in MAPTAM loaded cells. Conversely, 200nM ionomycin which elevated cytosolic Ca to an equivalent level to 10/sup -7/M FMLP, triggered a rise in /sup 14/C-DG but not in PA.

  3. Proteolytic cleavage of the urokinase receptor substitutes for the agonist-induced chemotactic effect.

    PubMed Central

    Resnati, M; Guttinger, M; Valcamonica, S; Sidenius, N; Blasi, F; Fazioli, F

    1996-01-01

    Physiological concentrations of urokinase plasminogen activator (uPA) stimulated a chemotactic response in human monocytic THP-1 through binding to the urokinase receptor (uPAR). The effect did not require the protease moiety of uPA, as stimulation was achieved also with the N-terminal fragment (ATF), while the 33 kDa low molecular weight uPA was ineffective. Co-immunoprecipitation experiments showed association of uPAR with intracellular kinase(s), as demonstrated by in vitro kinase assays. Use of specific antibodies identified p56/p59hck as a kinase associated with uPAR in THP-1 cell extracts. Upon addition of ATF, p56/p59hck activity was stimulated within 2 min and returned to normal after 30 min. Since uPAR lacks an intracellular domain capable of interacting with intracellular kinase, activation of p56/p59hck must require a transmembrane adaptor. Evidence for this was strongly supported by the finding that a soluble form of uPAR (suPAR) was capable of inducing chemotaxis not only in THP-1 cells but also in cells lacking endogenous uPAR (IC50, 5 pM). However, activity of suPAR require chymotrypsin cleavage between the N-terminal domain D1 and D2 + D3. Chymotrypsin-cleaved suPAR also induced activation of p56/p59hck in THP-1 cells, with a time course comparable with ATF. Our data show that uPA-induced signal transduction takes place via uPAR, involves activation of intracellular tyrosine kinase(s) and requires an as yet undefined adaptor capable of connecting the extracellular ligand binding uPAR to intracellular transducer(s). Images PMID:8612581

  4. Chemotactic and mitogenic stimuli of neuronal apoptosis in patients with medically intractable temporal lobe epilepsy

    PubMed Central

    Fiala, Milan; Avagyan, Hripsime; Merino, Jose Joaquin; Bernas, Michael; Valdivia, Juan; Espinosa-Jeffrey, Araceli; Witte, Marlys; Weinand, Martin

    2012-01-01

    To identify the upstream signals of neuronal apoptosis in patients with medically intractable temporal lobe epilepsy (TLE), we evaluated by immunohistochemistry and confocal microscopy brain tissues of 13 TLE patients and 5 control patients regarding expression of chemokines and cell-cycle proteins. The chemokine RANTES (CCR5) and other CC-chemokines and apoptotic markers (caspase-3, -8, -9) were expressed in lateral temporal cortical and hippocampal neurons of TLE patients, but not in neurons of control cases. The chemokine RANTES is usually found in cytoplasmic and extracellular locations. However, in TLE neurons, RANTES was displayed in an unusual location, the neuronal nuclei. In addition, the cell-cycle regulatory transcription factor E2F1 was found in an abnormal location in neuronal cytoplasm. The pro-inflammatory enzyme cyclooxygenase-2 and cytokine interleukin-1β were expressed both in neurons of patients suffering from temporal lobe epilepsy and from cerebral trauma. The vessels showed fibrin leakage, perivascular macrophages and expression of IL-6 on endothelial cells. In conclusion, the cytoplasmic effects of E2F1 and nuclear effects of RANTES might have novel roles in neuronal apoptosis of TLE neurons and indicate a need to develop new medical and/or surgical neuroprotective strategies against apoptotic signaling by these molecules. Both RANTES and E2F1 signaling are upstream from caspase activation, thus the antagonists of RANTES and/or E2F1 blockade might be neuroprotective for patients with medically intractable temporal lobe epilepsy. The results have implications for the development of new medical and surgical therapies based on inhibition of chemotactic and mitogenic stimuli of neuronal apoptosis in patients with medically intractable temporal lobe epilepsy. PMID:22444245

  5. Functional characterization of ferret CCL20 and CCR6 and identification of chemotactic inhibitors.

    PubMed

    Qin, Shulin; Klamar, Cynthia R; Fallert Junecko, Beth A; Craigo, Jodi; Fuller, Deborah H; Reinhart, Todd A

    2013-03-01

    CCL20 is currently the only known chemokine ligand for the receptor CCR6, and is a mucosal chemokine involved in normal and pathological immune responses. Although nucleotide sequence data are available for ccl20 and ccr6 sequences from multiple species, the ferret ccl20 and ccr6 sequences have not been determined. To increase our understanding of immune function in ferret models of infection and vaccination, we have used RT-PCR to obtain the ferret ccl20 and ccr6 cDNA sequences and functionally characterize the encoded proteins. The open reading frames of both genes were highly conserved across species and mostly closely related to canine sequences. For functional analyses, single cell clones expressing ferret CCR6 were generated, a ferret CCL20/mouse IgG(2a) fusion protein (fCCL20-mIgG(2a)) was produced, and fCCL20 was chemically synthesized. Cell clones expressing ferret CCR6 responded chemotactically to fCCL20-mIgG2a fusion protein and synthetic ferret CCL20. Chemotaxis inhibition studies identified the polyphenol epigallocatechin-3-gallate and the murine γ-herpesvirus 68 M3 protein as inhibitors of fCCL20. Surface plasmon resonance studies revealed that EGCG bound directly to fCCL20. These results provide molecular characterization of previously unreported ferret immune gene sequences and for the first time identify a broad-spectrum small molecule inhibitor of CCL20 and reveal CCL20 as a target for the herpesviral M3 protein. PMID:23360828

  6. Characterization of a receptor for human monocyte-derived neutrophil chemotactic factor/interleukin-8

    SciTech Connect

    Grob, P.M.; David, E.; Warren, T.C.; DeLeon, R.P.; Farina, P.R.; Homon, C.A. )

    1990-05-15

    Monocyte-derived neutrophil chemotactic factor/interleukin-8 (MDNCF/IL-8) is an 8,000-dalton protein produced by monocytes which exhibits activity as a chemoattractant for neutrophils with maximal activity achieved at a concentration of 50 ng/ml. This polypeptide has been iodinated by chloramine-T methodology (350 Ci/mM), and specific receptors for MDNCF/IL-8 have been detected on human neutrophils, U937 cells, THP-1 cells, and dimethyl sulfoxide-differentiated HL-60 cells. The binding of MDNCF/IL-8 to human neutrophils is not inhibited by interleukin-1 alpha, tumor necrosis factor-alpha, insulin, or epidermal growth factor. In addition, chemoattractants such as C5a, fMet-Leu-Phe, leukotriene B4, and platelet-activating factor fail to inhibit binding, suggesting that MDNCF/IL-8 utilizes a unique receptor. The receptor for MDNCF/IL-8 is apparently glycosylated since ligand binding is inhibited by the presence of wheat germ agglutinin, a lectin with a binding specificity for N-acetylglucosamine and neuraminic acid. Steady state binding experiments indicate Kd values of 4 and 0.5 nM and receptor numbers of 75,000 and 7,400 for human neutrophils and differentiated HL-60 cells, respectively. 125I-MDNCF/IL-8 bound to human neutrophils is rapidly internalized and subsequently released from cells as trichloroacetic acid-soluble radioactivity. Affinity labeling experiments suggest that the human neutrophil MDNCF/IL-8 receptor exhibits a mass of approximately 58,000 daltons.

  7. Coccidioides Endospores and Spherules Draw Strong Chemotactic, Adhesive, and Phagocytic Responses by Individual Human Neutrophils

    PubMed Central

    Lee, Cheng-Yuk; Thompson III, George R.; Hastey, Christine J.; Hodge, Gregory C.; Lunetta, Jennine M.; Pappagianis, Demosthenes; Heinrich, Volkmar

    2015-01-01

    Coccidioides spp. are dimorphic pathogenic fungi whose parasitic forms cause coccidioidomycosis (Valley fever) in mammalian hosts. We use an innovative interdisciplinary approach to analyze one-on-one encounters between human neutrophils and two forms of Coccidioides posadasii. To examine the mechanisms by which the innate immune system coordinates different stages of the host response to fungal pathogens, we dissect the immune-cell response into chemotaxis, adhesion, and phagocytosis. Our single-cell technique reveals a surprisingly strong response by initially quiescent neutrophils to close encounters with C. posadasii, both from a distance (by complement-mediated chemotaxis) as well as upon contact (by serum-dependent adhesion and phagocytosis). This response closely resembles neutrophil interactions with Candida albicans and zymosan particles, and is significantly stronger than the neutrophil responses to Cryptococcus neoformans, Aspergillus fumigatus, and Rhizopus oryzae under identical conditions. The vigorous in vitro neutrophil response suggests that C. posadasii evades in vivo recognition by neutrophils through suppression of long-range mobilization and recruitment of the immune cells. This observation elucidates an important paradigm of the recognition of microbes, i.e., that intact immunotaxis comprises an intricate spatiotemporal hierarchy of distinct chemotactic processes. Moreover, in contrast to earlier reports, human neutrophils exhibit vigorous chemotaxis toward, and frustrated phagocytosis of, the large spherules of C. posadasii under physiological-like conditions. Finally, neutrophils from healthy donors and patients with chronic coccidioidomycosis display subtle differences in their responses to antibody-coated beads, even though the patient cells appear to interact normally with C. posadasii endospores. PMID:26070210

  8. Enterohepatic circulation of bacterial chemotactic peptide in rats with experimental colitis

    SciTech Connect

    Hobson, C.H.; Butt, T.J.; Ferry, D.M.; Hunter, J.; Chadwick, V.S.; Broom, M.F.

    1988-04-01

    The association of hepatobiliary disorders with colonic inflammation is well recognized. Although the pathophysiology is obscure, increased permeation of toxic bacterial products across the inflamed gut to the portal circulation might be one mechanism. Potentially toxic metabolites include N-formylated chemotactic peptides that are produced by several species of intestinal bacteria and can be detected in colonic fluid in vivo. To investigate the metabolic fate of one of these low molecular weight proinflammatory peptides, N-formyl L-methionine L-leucine /sup 125/I-L-tyrosine was introduced into colon loops of healthy rats (n = 10) and rats with experimental colitis (n = 15) induced by rectal instillation of 15% (vol/vol) acetic acid. Gut, liver, and blood radioactivity were monitored by external gamma-counting and radioactivity in bile was measured by biliary catheter drainage into a well counter. Bile was processed by high-performance liquid chromatography to determine the amount of intact, bioactive peptide excreted over 3 h. After colonic instillation of 1 nmol of peptide, the mean (+/- SEM) biliary excretion of intact peptide was 6.4 +/- 2.0 pmol in normal rats and 49.0 +/- 20 pmol in rats with colitis (p less than 0.01). An enterohepatic circulation of synthetic N-formyl L-methionine L-leucine L-tyrosine has been demonstrated in the rat. Experimental colitis was associated with an eightfold increase in biliary excretion of this proinflammatory bacterial peptide. Proinflammatory bacterial peptides synthesized by colonic bacteria could be important in the pathophysiology of colon inflammation and its frequently associated hepatobiliary complications.

  9. Identification and partial characterization of an exercise-induced neutrophil chemotactic factor in bronchial asthma.

    PubMed Central

    Lee, T H; Nagy, L; Nagakura, T; Walport, M J; Kay, A B

    1982-01-01

    A heat-stable neutrophil chemotactic factor (NCF) has been identified in the serum of 13 atopic asthmatic subjects after treadmill exercise. Peak activity was detected at 10 min and returned to prechallenge values by 1 h. No NCF activity was detected in the sera of three nonasthmatic atopic or four normal nonatopic individuals performing the same task. NCF produced by exercise (NCFEX) had a similar time-course of release to NCF provoked by specific antigen (NCFAG). The appearance of circulating NCFEX and NCFAG closely paralleled the fall in peak expiratory flow rate/forced expiratory volume in 1 s (PEFR/FEV1). Histamine challenge in atopic asthmatics at concentrations giving a comparable change in PEFR/FEV1 to that evoked by exercise or inhaled antigen was not associated with the appearance of circulating NCF. In seven subjects NCFEX release was inhibited by prior administration of disodium cromoglycate. NCFEX and NCFAG eluted as single peaks of activity when applied separately to columns of Sephadex G-200, and both were an estimated 750,000 daltons. NCFEX and NCFAG also eluted as single peaks of activity, at between 0.15 and 0.30 M NaCl, following anion exchange chromatography on DEAE-Sephacel (pH 7.8). The isoelectric points of NCFEX and NCFAG were virtually identical (between pH 6.0 and 6.5) as determined by chromatofocusing on Polybuffer Exchanger 94. The activities of NCFEX and NCFAG were substantially reduced, in both a time- and dose-dependent fashion, after incubation with trypsin and chymotrypsin. Partially purified NCFEX and NCFAG promoted both stimulated random migration (chemokinesis) as well as directional migration (chemotaxis). These experiments indicate that NCFEX and NCFAG might be identical substances and raise the possibility that mediators by hypersensitivity are released during exercise-induced asthma in atopic subjects. PMID:7076852

  10. Sonic hedgehog is a chemotactic neural crest cell guide that is perturbed by ethanol exposure.

    PubMed

    Tolosa, Ezequiel J; Fernández-Zapico, Martín E; Battiato, Natalia L; Rovasio, Roberto A

    2016-01-01

    Our aim was to understand the involvement of Sonic hedgehog (Shh) morphogen in the oriented distribution of neural crest cells (NCCs) toward the optic vesicle and to look for potential disorders of this guiding mechanism after ethanol exposure. In vitro directional analysis showed the chemotactic response of NCCs up Shh gradients and to notochord co-cultures (Shh source) or to their conditioned medium, a response inhibited by anti-Shh antibody, receptor inhibitor cyclopamine and anti-Smo morpholino (MO). Expression of the Ptch-Smo receptor complex on in vitro NCCs was also shown. In whole embryos, the expression of Shh mRNA and protein was seen in the ocular region, and of Ptch, Smo and Gli/Sufu system on cephalic NCCs. Anti-Smo MO or Ptch-mutated plasmid (Ptch1(Δloop2)) impaired cephalic NCC migration/distribution, with fewer cells invading the optic region and with higher cell density at the homolateral mesencephalic level. Beads embedded with cyclopamine (Smo-blocking) or Shh (ectopic signal) supported the role of Shh as an in vivo guide molecule for cephalic NCCs. Ethanol exposure perturbed in vitro and in vivo NCC migration. Early stage embryos treated with ethanol, in a model reproducing Fetal Alcohol Syndrome, showed later disruptions of craniofacial development associated with abnormal in situ expression of Shh morphogen. The results show the Shh/Ptch/Smo-dependent migration of NCCs toward the optic vesicle, with the support of specific inactivation with genetic and pharmacological tools. They also help to understand mechanisms of accurate distribution of embryonic cells and of their perturbation by a commonly consumed teratogen, and demonstrate, in addition to its other known developmental functions, a new biological activity of cellular guidance for Shh. PMID:26979762

  11. Chemotactic signal transduction and phosphate metabolism as adaptive strategies during citrus canker induction by Xanthomonas citri.

    PubMed

    Moreira, Leandro Marcio; Facincani, Agda Paula; Ferreira, Cristiano Barbalho; Ferreira, Rafael Marine; Ferro, Maria Inês Tiraboshi; Gozzo, Fabio Cesar; de Oliveira, Julio Cezar Franco; Ferro, Jesus Aparecido; Soares, Márcia Regina

    2015-03-01

    The genome of Xanthomonas citri subsp. Citri strain 306 pathotype A (Xac) was completely sequenced more than 10 years; to date, few studies involving functional genomics Xac and its host compatible have been developed, specially related to adaptive events that allow the survival of Xac within the plant. Proteomic analysis of Xac showed that the processes of chemotactic signal transduction and phosphate metabolism are key adaptive strategies during the interaction of a pathogenic bacterium with its plant host. The results also indicate the importance of a group of proteins that may not be directly related to the classical virulence factors, but that are likely fundamental to the success of the initial stages of the infection, such as methyl-accepting chemotaxis protein (Mcp) and phosphate specific transport (Pst). Furthermore, the analysis of the mutant of the gene pstB which codifies to an ABC phosphate transporter subunit revealed a complete absence of citrus canker symptoms when inoculated in compatible hosts. We also conducted an in silico analysis which established the possible network of genes regulated by two-component systems PhoPQ and PhoBR (related to phosphate metabolism), and possible transcriptional factor binding site (TFBS) motifs of regulatory proteins PhoB and PhoP, detaching high degree of conservation of PhoB TFBS in 84 genes of Xac genome. This is the first time that chemotaxis signal transduction and phosphate metabolism were therefore indicated to be fundamental to the process of colonization of plant tissue during the induction of disease associated with Xanthomonas genus bacteria. PMID:25403594

  12. [Determination of the neutrophil chemotactic factor in bronchoalveolar lavage fluid in patients with diffuse panbronchiolitis].

    PubMed

    Oda, H; Kadota, J; Sakito, O; Mukae, H; Morikawa, N; Shukuwa, C; Senju, R; Sawa, H; Kusano, S; Morikawa, T

    1992-04-01

    It is well known that erythromycin (EM) therapy is effective on chronic lower respiratory tract disease, including diffuse panbronchiolitis (DPB). In this study we investigated the relationship between clinical findings and neutrophil chemotactic activity (NCA) in bronchoalveolar lavage fluid (BALF) in patients with DPB receiving orally EM therapy. The NCA in post-EM therapy BALF was significantly reduced (p less than 0.001) compared with that in BALF before EM therapy (30.17 +/- 7.84% vs 53.05 +/- 10.65%). On the respiratory function before and after EM therapy, DPB patients (20 cases) showed significant improvement of %VC, FEV1.0, RV/TLC (p less than 0.001, each) and V25 (p less than 0.05). And on the post-EM therapy blood gas, PaO2 and AaDO2 level were confirmed to be significantly improved (p less than 0.001). In addition, we examined the correlation between the improvement ratio of clinical finding and the reduction of NCA in BALF after EM therapy in 10 patients with DPB. We found the significant correlation between the improvement ratio of PaO2 and the reduction NCA in BALF of those patients (p less than 0.05). There were no significant relationships between the improvement ratio in other parameters as stated above and the reduction of NCA in BALF. These findings indicate that EM restrains the NCA in BALF of patients with DPB and impairs the accumulation of neutrophils in respiratory tract, ultimately contributes to the improvement of clinical symptoms such as sputum and clinical findings such as PaO2 in patients with DPB. PMID:1624836

  13. Chemotactic response of marine micro-organisms to micro-scale nutrient layers.

    PubMed

    Seymour, Justin R; Marcos; Stocker, Roman

    2007-01-01

    The degree to which planktonic microbes can exploit microscale resource patches will have considerable implications for oceanic trophodynamics and biogeochemical flux. However, to take advantage of nutrient patches in the ocean, swimming microbes must overcome the influences of physical forces including molecular diffusion and turbulent shear, which will limit the availability of patches and the ability of bacteria to locate them. Until recently, methodological limitations have precluded direct examinations of microbial behaviour within patchy habitats and realistic small-scale flow conditions. Hence, much of our current knowledge regarding microbial behaviour in the ocean has been procured from theoretical predictions. To obtain new information on microbial foraging behaviour in the ocean we have applied soft lithographic fabrication techniques to develop 2 microfluidic devices, which we have used to create (i) microscale nutrient patches with dimensions and diffusive characteristics relevant to oceanic processes and (ii) microscale vortices, with shear rates corresponding to those expected in the ocean. These microfluidic devices have permitted a first direct examination of microbial swimming and chemotactic behaviour within a heterogeneous and dynamic seascape. The combined use of epifluorescence and phase contrast microscopy allow direct examinations of the physical dimensions and diffusive characteristics of nutrient patches, while observing the population-level aggregative response, in addition to the swimming behaviour of individual microbes. These experiments have revealed that some species of phytoplankton, heterotrophic bacteria and phagotrophic protists are adept at locating and exploiting diffusing microscale resource patches within very short time frames. We have also shown that up to moderate shear rates, marine bacteria are able to fight the flow and swim through their environment at their own accord. However, beyond a threshold high shear level

  14. Single Amino Acid Substitutions in the Chemotactic Sequence of Urokinase Receptor Modulate Cell Migration and Invasion

    PubMed Central

    Franco, Paola; Pavone, Vincenzo; Mugione, Pietro; Di Carluccio, Gioconda; Masucci, Maria Teresa; Arra, Claudio; Pirozzi, Giuseppe; Stoppelli, Maria Patrizia; Carriero, Maria Vincenza

    2012-01-01

    The receptor for urokinase-type plasminogen activator (uPAR) plays an important role in controlling cell migration. uPAR binds urokinase and vitronectin extracellular ligands, and signals in complex with transmembrane receptors such as Formyl-peptide Receptors (FPR)s and integrins. Previous work from this laboratory has shown that synthetic peptides, corresponding to the uPAR88–92 chemotactic sequence, when carrying the S90P or S90E substitutions, up- or down-regulate cell migration, respectively. To gain mechanistic insights into these opposite cell responses, the functional consequences of S90P and S90E mutations in full-length uPAR were evaluated. First, (HEK)-293 embryonic kidney cells expressing uPARS90P exhibit enhanced FPR activation, increased random and directional cell migration, long-lasting Akt phosphorylation, and increased adhesion to vitronectin, as well as uPAR/vitronectin receptor association. In contrast, the S90E substitution prevents agonist-triggered FPR activation and internalization, decreases binding and adhesion to vitronectin, and inhibits uPAR/vitronectin receptor association. Also, 293/uPARS90P cells appear quite elongated and their cytoskeleton well organized, whereas 293/uPARS90E cells assume a large flattened morphology, with random orientation of actin filaments. Interestingly, when HT1080 cells co-express wild type uPAR with uPAR S90E, the latter behaves as a dominant-negative, impairing uPAR-mediated signaling and reducing cell wound repair as well as lung metastasis in nude mice. In contrast, signaling, wound repair and in vivo lung metastasis of HT1080 cells bearing wild type uPAR are enhanced when they co-express uPARS90P. In conclusion, our findings indicate that Ser90 is a critical residue for uPAR signaling and that the S90P and S90E exert opposite effects on uPAR activities. These findings may be accommodated in a molecular model, in which uPARS90E and uPARS90P are forced into inactive and active forms, respectively

  15. Chemotactic responses of Escherichia coli to small jumps of photoreleased L-aspartate.

    PubMed

    Jasuja, R; Keyoung, J; Reid, G P; Trentham, D R; Khan, S

    1999-03-01

    Computer-assisted motion analysis coupled to flash photolysis of caged chemoeffectors provides a means for time-resolved analysis of bacterial chemotaxis. Escherichia coli taxis toward the amino acid attractant L-aspartate is mediated by the Tar receptor. The physiology of this response, as well as Tar structure and biochemistry, has been studied extensively. The beta-2, 6-dinitrobenzyl ester of L-aspartic acid and the 1-(2-nitrophenyl)ethyl ether of 8-hydroxypyrene-1,3,6-tris-sulfonic acid were synthesized. These compounds liberated L-aspartate and the fluorophore 8-hydroxypyrene 1,3,6-tris-sulfonic acid (pyranine) upon irradiation with near-UV light. Photorelease of the fluorophore was used to define the amplitude and temporal stability of the aspartate jumps employed in chemotaxis experiments. The dependence of chemotactic adaptation times on aspartate concentration, determined in mixing experiments, was best fit by two Tar aspartate-binding sites. Signal processing (excitation) times, amplitudes, and adaptive recovery of responses elicited by aspartate jumps producing less than 20% change in receptor occupancy were characterized in photorelease assays. Aspartate concentration jumps in the nanomolar range elicited measurable responses. The response threshold and sensitivity of swimming bacteria matched those of bacteria tethered to glass by a single flagellum. Stimuli of similar magnitude, delivered either by rapid mixing or photorelease, evoked responses of similar strength, as assessed by recovery time measurements. These times remained proportional to change in receptor occupancy close to threshold, irrespective of prior occupancy. Motor excitation responses decayed exponentially with time. Rates of excitation responses near threshold ranged from 2 to 7 s-1. These values are consistent with control of excitation signaling by decay of phosphorylated pools of the response regulator protein, CheY. Excitation response rates increased slightly with stimulus size

  16. Monocyte chemotactic protein-1 provokes mast cell aggregation and [3H]5HT release.

    PubMed Central

    Conti, P; Boucher, W; Letourneau, R; Feliciani, C; Reale, M; Barbacane, R C; Vlagopoulos, P; Bruneau, G; Thibault, J; Theoharides, T C

    1995-01-01

    Monocyte chemotactic protein-1 (MCP-1) and MCP-3, the most active and representative compounds of the CC chemokine family, are proinflammatory cytokines that attract and activate specific types of leucocytes. We have used highly purified isolated rat peritoneal mast cells (RPMC) cultured for different lengths of time with and without MCP-1 (200, 100, 50 and 25 nM). Our data clearly show that MCP-1 (200 nM) causes a marked release of [3H]serotonin ([3H]5HT and histamine, which reach a peak at 40 min of incubation (56.6 +/- 5.3 and 34.7 +/- 6 above the control, respectively). In dose-response experiments, MCP-1 (200, 100, 50, 25, 12.5, 6.25 and 3.12 nM) provoked a dose-dependent release of [3H]5HT and histamine from RPMC, which was maximum at 200 nM. After preparation of the histidine decarboxylase (HDC) probe, a Northern blot analysis was determined for HDC mRNA. After 4 hr, steady-state levels of HDC mRNA were induced in a dose-dependent manner by MCP-1 (200-25 nM), compared to the controls. However, MCP-1 failed to prime RPMC in [3H]5HT and histamine release when C48/80 (0.05 micrograms/ml) or anti-IgE was used. In contrast, murine interleukin-3 (IL-3) in combination with MCP-1 (200 and 100 nM) provoked a greater release of histamine and [3H]5HT than the compounds alone. Moreover, RPMC treated with MCP-1 (200 nM) showed, under light microscopy (20x), greater clump formation, a phenomenon absent in the controls (untreated cells). The electron microscope studies revealed that treatment with MCP-1 (200 nM) promoted binding of RPMC and clearly demonstrated a communication between the cytoplasms of adjacent mast cells. Our report describes additional biological activities for MCP-1, suggesting for the first time that this human monocyte chemoattractant plays a fundamental role in histamine and serotonin release and cell aggregation in rat peritoneal mast cells. Images Figure 4 Figure 5 PMID:8550082

  17. Prey-Specific Growth Responses of Freshwater Flagellate Communities Induced by Morphologically Distinct Bacteria from the Genus Limnohabitans.

    PubMed

    Grujčić, Vesna; Kasalický, Vojtěch; Šimek, Karel

    2015-08-01

    Because their large growth potential is counterbalanced with grazing by heterotrophic nanoflagellates (HNF), bacteria of the genus Limnohabitans, which are common in many freshwater habitats, represent a valuable model for examining bacterial carbon flow to the grazer food chain. We conducted experiments with natural HNF communities taken from two distinct habitats, the meso-eutrophic Římov Reservoir and the oligo-mesotrophic Lake Cep (South Bohemia). HNF communities from each habitat at distinct seasonal phases, a late April algal bloom and a late May clear water phase, were each fed 3 Limnohabitans strains of differing cell sizes. Water samples were prefiltered (5 μm) to release natural HNF communities from zooplankton control and then amended with the Limnohabitans strains L. planktonicus II-D5 (medium sized, rod shaped), Limnohabitans sp. strain T6-5 (thin, long, curved rod), and Limnohabitans sp. strain 2KL-3 (large solenoid). Using temporal sampling and prey treatment, we determined HNF growth parameters such as doubling time, growth efficiency, and length of lag phase prior starting to exponential growth. All three Limnohabitans strains supported HNF growth but in significant prey-, site-, and season-dependent fashions. For instance, addition of the moderately large T6-5 strain yielded very rapid HNF growth with a short lag phase. In contrast, the curved morphology and larger cell size of strain 2KL-3 made this prey somewhat protected against grazing by smaller HNF, resulting in slower HNF growth and longer lag phases. These trends were particularly pronounced during the late May clear-water phase, which was dominated by smaller HNF cells. This may indicate a longer "adaptation time" for the flagellate communities toward the large prey size offered. PMID:25979896

  18. Prey-Specific Growth Responses of Freshwater Flagellate Communities Induced by Morphologically Distinct Bacteria from the Genus Limnohabitans

    PubMed Central

    Grujčić, Vesna; Kasalický, Vojtěch

    2015-01-01

    Because their large growth potential is counterbalanced with grazing by heterotrophic nanoflagellates (HNF), bacteria of the genus Limnohabitans, which are common in many freshwater habitats, represent a valuable model for examining bacterial carbon flow to the grazer food chain. We conducted experiments with natural HNF communities taken from two distinct habitats, the meso-eutrophic Římov Reservoir and the oligo-mesotrophic Lake Cep (South Bohemia). HNF communities from each habitat at distinct seasonal phases, a late April algal bloom and a late May clear water phase, were each fed 3 Limnohabitans strains of differing cell sizes. Water samples were prefiltered (5 μm) to release natural HNF communities from zooplankton control and then amended with the Limnohabitans strains L. planktonicus II-D5 (medium sized, rod shaped), Limnohabitans sp. strain T6-5 (thin, long, curved rod), and Limnohabitans sp. strain 2KL-3 (large solenoid). Using temporal sampling and prey treatment, we determined HNF growth parameters such as doubling time, growth efficiency, and length of lag phase prior starting to exponential growth. All three Limnohabitans strains supported HNF growth but in significant prey-, site-, and season-dependent fashions. For instance, addition of the moderately large T6-5 strain yielded very rapid HNF growth with a short lag phase. In contrast, the curved morphology and larger cell size of strain 2KL-3 made this prey somewhat protected against grazing by smaller HNF, resulting in slower HNF growth and longer lag phases. These trends were particularly pronounced during the late May clear-water phase, which was dominated by smaller HNF cells. This may indicate a longer “adaptation time” for the flagellate communities toward the large prey size offered. PMID:25979896

  19. The monocyte chemotactic protein a (MCP-1) and interleukin 8 (IL-8) in Hodgkin's disease and in solid tumours.

    PubMed Central

    Luciani, M G; Stoppacciaro, A; Peri, G; Mantovani, A; Ruco, L P

    1998-01-01

    AIMS: Monocyte chemotactic protein 1 (MCP-1) and interleukin 8 (IL-8) are small, inducible proteins with chemotactic activity for specific subsets of leucocytes. The possibility that MCP-1 and IL-8 are produced in tissues involved by Hodgkin's disease, thus contributing to the inflammatory-type background of the lesion, was investigated. METHODS: The presence of RNA transcripts for MCP-1 and IL-8 was investigated in biopsy samples of 24 cases of Hodgkin's disease, 17 non-Hodgkin's malignant lymphomas, 30 solid tumours, and 30 histologically normal tissues by means of reverse transcription-polymerase chain reaction (RT-PCR)/Southern blot analysis. RESULTS: MCP-1 expression was detected in 23 of 24 cases of Hodgkin's disease, in seven of 17 cases of B cell non-Hodgkin's lymphoma, and in seven of 14 cases of reactive lymphoid hyperplasia. IL-8 was present in six of 14 cases of Hodgkin's disease, and was seen only rarely in B cell non-Hodgkin's lymphoma and in reactive lymphoid tissues. MCP-1 and IL-8 RNA transcripts were detected in 13 of 25 carcinomas originating from the lung, breast, thyroid, and ovary. CONCLUSIONS: These findings are consistent with the possibility that MCP-1 and IL-8 are two additional cytokines involved in the pathogenesis of Hodgkin's disease. PMID:10193522

  20. Chemotactic response of plant-growth-promoting bacteria towards roots of vesicular-arbuscular mycorrhizal tomato plants.

    PubMed

    Gupta Sood, Sushma

    2003-08-01

    The chemotactic responses of the plant-growth-promoting rhizobacteria Azotobacter chroococcum and Pseudomonas fluorescens to roots of vesicular-arbuscular mycorrhizal (Glomus fasciculatum) tomato plants were determined. A significantly (P=0.05) greater number of bacterial cells of wild strains were attracted towards vesicular-arbuscular mycorrhizal tomato roots compared to non-vesicular-arbuscular mycorrhizal tomato roots. Substances exuded by roots served as chemoattractants for these bacteria. P. fluorescens was strongly attracted towards citric and malic acids, which were predominant constituents in root exudates of tomato plants. A. chroococcum showed a stronger response towards sugars than amino acids, but the response was weakest towards organic acids. The effects of temperature, pH, and soil water matric potential on bacterial chemotaxis towards roots were also investigated. In general, significantly (P=0.05) greater chemotactic responses of bacteria were observed at higher water matric potentials (0, -1, and -5 kPa), slightly acidic to neutral pH (6, 6.5 and 7), and at 20-30 degrees C (depending on the bacterium) than in other environmental conditions. It is suggested that chemotaxis of P. fluorescens and A. chroococcum towards roots and their exudates is one of the several steps in the interaction process between bacteria and vesicular-arbuscular mycorrhizal roots. PMID:19719591

  1. Stimulus-specific deactivation of chemotactic factor-induced cyclic AMP response and superoxide generation by human neutrophils.

    PubMed Central

    Simchowitz, L; Atkinson, J P; Spilberg, I

    1980-01-01

    The responses of isolated human peripheral neutrophils to either simultaneous or sequential additions of two chemotactic factors were studied. Simultaneous additions of formyl-methionyl-leucyl-phenylalanine (10-100 nM) and the fifth component of complement, C5a (1-10 microliters/ml), evoked partially additive responses of membrane depolarization as measured by the fluorescent dye 3,3'-dipropyl-thiocarbocyanine, a transient elevation of intracellular cyclic AMP (cAMP), and superoxide (O2-) generation as assessed by ferricytochrome c reduction. Preincubation of the cells with either formyl-methionyl-leucyl-phenylalanine or C5a alone caused dose-dependent inhibition of the depolarization, the cAMP increase, and O2- release induced by a subsequent exposure to an optimal dose of the same stimulus, i.e., deactivation occurred. In contrast, when cells were treated with one chemotactic factor and then exposed to the other stimulus, the cells exhibited a normal response of peak depolarization, the rise in cAMP, and O2-0 production i.e., cross-deactivation failed to occur. The results imply that deactivation of these phenomena is stimulus specific. Further, these observations are consistent with the hypothesis that cross-deactivation of chemotaxis is mediated by one or more processes that are irrelevant to O2- generation, and that occur distal to the depolarization and cAMP steps in the sequence of neutrophil activation: possibly microtubule polymerization and orientation. PMID:6252250

  2. In vitro inhibitory effects of Moringa oleifera leaf extract and its major components on chemiluminescence and chemotactic activity of phagocytes.

    PubMed

    Vongsak, Boonyadist; Gritsanapan, Wandee; Wongkrajang, Yuvadee; Jantan, Ibrahim

    2013-11-01

    The ethanol extract of Moringa oleifera Lam. leaves and its major constituents, crypto-chlorogenic acid, quercetin 3-O-glucoside and kaempferol 3-O-glucoside, were investigated on the respiratory burst of human whole blood and isolated human polymorphonuclear leukocytes (PMNs) using a luminol-based chemiluminescence assay. The chemotactic migration of PMNs was also investigated using the Boyden chamber technique. The ethanol extract demonstrated inhibitory activities on the oxidative burst and the chemotactic migration of PMNs. Quercetin 3-O-glucoside, crypto-chlorogenic acid, and kaempferol 3-O-glucoside, isolated from the extract, expressed relatively strong inhibitory activity on the oxidative burst of PMNs with IC50 values of 4.1, 6.7 and 7.0 microM, respectively, comparable with that of aspirin. They also demonstrated strong inhibition of chemotatic migration of PMNs with IC50 values of 9.5, 15.9 and 18.2 microM, respectively. The results suggest that M. oleifera leaves could modulate the immune response of human phagocytes, linking to its ethnopharmacological use as an anti-inflammatory agent. The immunomodulating activity of the plant was mainly due to its major components. PMID:24427941

  3. [Aortic expression of monocyte chemotactic protein-1 (MCP-1) gene in rabbits with experimental atherosclerosis].

    PubMed

    Sekalska, Beata

    2003-01-01

    The theory of Ross describes atherosclerosis as a process induced by inflammatory reactions involving cytokines, cell adhesion molecules, and chemokines. The latter have been identified as the principal mediator of cell recruitment into the vascular wall when accumulating monocytes become a source of foam cells. The most potent monocyte attractant among known chemokines is the monocyte chemotactic protein-1 (MCP-1). This protein is synthesized in vivo by cells of the vascular wall and its expression is largely controlled by NF-kB nuclear transcription factor. The importance of inflammation for the induction and progression of atherosclerosis suggests that anti-inflammatory drugs could be a useful modality in this condition. The present work was undertaken to: 1) adapt the RT-PCR technique to measurements of MCP-1 gene expression in rabbit aorta, 2) assess MCP-1 gene expression in rabbit aorta during atherosclerosis induced with a cholesterol-rich diet, 3) evaluate the effect of ibuprofen on MCP-1 gene expression in rabbit aorta during atherosclerosis induced with a cholesterol-rich diet. The study was done in 72 rabbits assigned to eight even groups on the basis of body weight and starting cholesterol and triglyceride concentrations in serum. All rabbits were fed a standard chow. In some groups, the diet was supplemented with cholesterol and/or ibuprofen. Two months later rabbits in four groups, i.e. control (K2), control with ibuprofen (IK2), cholesterol-rich (M2) and cholesterol-rich with ibuprofen (IM2) were weighed and blood was sampled for measurements of cholesterol and triglyceride concentrations in serum. The liver, heart, kidneys and adrenals were collected at autopsy and weighed. Additionally, a fragment of the ascending aorta was obtained for RT-PCR. The extent of atherosclerosis in aorta was determined using planimetry. Another month later this procedure was repeated for the remaining groups K3, IK3, M3 and IM3. RT-PCR was applied to measure MCP-1 gene

  4. Sex and flagellation.

    PubMed

    Hurst, L; Grafen, A

    1990-12-01

    The centriole is one of the cell's more enigmatic structures. It lives a Jekyll and Hyde existence, changing from the basal body, which seeds the production of cilia and flagellae, into the centriole, in which guise it is of uncertain function. Recent work has indicated the possibility of DNA tightly packed into the structure's core. This finding sheds light on theories of the evolutionary origins of the centriole and of its possible involvement in the evolution of sex. Recent experimental work has been testing this latter possibility. PMID:21232406

  5. Chemotactic signaling by the P1 phosphorylation domain liberated from the CheA histidine kinase of Escherichia coli.

    PubMed Central

    Garzón, A; Parkinson, J S

    1996-01-01

    CheA is a histidine kinase central to the signal transduction pathway for chemotaxis in Escherichia coli. CheA autophosphorylates at His-48, with ATP as the phosphodonor, and then donates its phosphoryl groups to two aspartate autokinases, CheY and CheB. Phospho-CheY controls the flagellar motors, whereas phospho-CheB participates in sensory adaptation. Polypeptides encompassing the N-terminal P1 domain of CheA can be transphosphorylated in vitro by the CheA catalytic domain and yet have no deleterious effect on chemotactic ability when expressed at high levels in wild-type cells. To find out why, we examined the effects of a purified P1 fragment, CheA[1-149], on CheA-related signaling activities in vitro and devised in vivo assays for those same activities. Although readily phosphorylated by CheA[260-537], the CheA catalytic domain, CheA[1-149], was a poor substrate for transphosphorylation by full-length CheA molecules, implying that the resident P1 domain monopolizes the CheA catalytic center. CheA-H48Q, a nonphosphorylatable mutant, failed to transphosphorylate CheA[1-149], suggesting that phosphorylation of the P1 domain in cis may alleviate the exclusion effect. In agreement with these findings, a 40-fold excess of CheA[1-149] fragments did not impair the CheA autophosphorylation reaction. CheA[1-149] did acquire phosphoryl groups via reversible phosphotransfer reactions with CheB and CheY molecules. An H48Q mutant of CheA[1-149] could not participate in these reactions, indicating that His-48 is probably the substrate site. The low level of efficiency of these phosphotransfer reactions and the inability of CheA[1-149] to interfere with CheA autophosphorylation most likely account for the failure of liberated P1 domains to jam chemotactic signaling in wild-type cells. However, an excess of CheA[1-149] fragments was able to support chemotactic signaling by P1-deficient cheA mutants, demonstrating that CheA[1-149] fragments have both transphosphorylation and

  6. Monocyte chemotactic protein-1 secretion and expression after Toxoplasma gondii infection in vitro depend on the stage of the parasite.

    PubMed

    Brenier-Pinchart, Marie-Pierre; Vigan, Inés; Jouvin-Marche, Evelyne; Marche, Patrice Noél; Pelet, Elisabeth; Gross, Uwe; Ambroise-Thomas, Pierre; Pelloux, Hervé

    2002-08-27

    Infection of human fibroblasts with tachyzoites of RH and Prugniaud strains, two different strains of Toxoplasma gondii, significantly increased monocyte chemotactic protein (MCP)-1 secretion contrary to what happened with bradyzoites of the cystogenetic strain. Quantification of MCP-1 mRNA by RT-PCR showed that this phenomenon is regulated at the transcriptional level. Thus, the stage of parasite can be deciding in MCP-1 induction since only tachyzoites induced MCP-1 expression and secretion. MCP-1 induced by tachyzoites could be involved in cell recruitment, as shown by the quantification of MCP1 ARNm by real-time PCR (LightCycler, Roche Diagnostics), in the pathogenesis of T. gondii infection. PMID:12204371

  7. Multiscale dynamics of biological cells with chemotactic interactions: From a discrete stochastic model to a continuous description

    NASA Astrophysics Data System (ADS)

    Alber, Mark; Chen, Nan; Glimm, Tilmann; Lushnikov, Pavel M.

    2006-05-01

    The cellular Potts model (CPM) has been used for simulating various biological phenomena such as differential adhesion, fruiting body formation of the slime mold Dictyostelium discoideum, angiogenesis, cancer invasion, chondrogenesis in embryonic vertebrate limbs, and many others. We derive a continuous limit of a discrete one-dimensional CPM with the chemotactic interactions between cells in the form of a Fokker-Planck equation for the evolution of the cell probability density function. This equation is then reduced to the classical macroscopic Keller-Segel model. In particular, all coefficients of the Keller-Segel model are obtained from parameters of the CPM. Theoretical results are verified numerically by comparing Monte Carlo simulations for the CPM with numerics for the Keller-Segel model.

  8. Chemotactic Activity of Cyclophilin A in the Skin Mucus of Yellow Catfish (Pelteobagrus fulvidraco) and Its Active Site for Chemotaxis.

    PubMed

    Dawar, Farman Ullah; Tu, Jiagang; Xiong, Yang; Lan, Jiangfeng; Dong, Xing Xing; Liu, Xiaoling; Khattak, Muhammad Nasir Khan; Mei, Jie; Lin, Li

    2016-01-01

    Fish skin mucus is a dynamic barrier for invading pathogens with a variety of anti-microbial enzymes, including cyclophilin A (CypA), a multi-functional protein with peptidyl-prolyl cis/trans isomerase (PPIase) activity. Beside various other immunological functions, CypA induces leucocytes migration in vitro in teleost. In the current study, we have discovered several novel immune-relevant proteins in yellow catfish skin mucus by mass spectrometry (MS). The CypA present among them was further detected by Western blot. Moreover, the CypA present in the skin mucus displayed strong chemotactic activity for yellow catfish leucocytes. Interestingly, asparagine (like arginine in mammals) at position 69 was the critical site in yellow catfish CypA involved in leucocyte attraction. These novel efforts do not only highlight the enzymatic texture of skin mucus, but signify CypA to be targeted for anti-inflammatory therapeutics. PMID:27589721

  9. Prevalence and organ distribution of leukocyte chemotactic factor 2 amyloidosis (ALECT2) among decedents in New Mexico

    PubMed Central

    Larsen, Christopher P.; Beggs, Marjorie L.; Wilson, Jon D.; Lathrop, Sarah L.

    2016-01-01

    Abstract Leukocyte chemotactic factor 2 (LECT2) amyloidosis is one of the most recently described types of amyloidosis. Since its description, it has been found to be one the most common types of amyloidosis in large series of amyloid cases involving the kidney and liver in the United States, where it primarily affects patients of Hispanic ethnicity. We sought to investigate the prevalence of this disease among Hispanic adult decedents who had an autopsy performed at the New Mexico Office of the Medical Investigator and determine the organ distribution of amyloid deposition. LECT2 amyloid deposits were identified within the kidney in 3.1% of Hispanic decedents. It was consistently deposited in the liver, spleen, adrenals, and lungs but did not involve the myocardium or brain. LECT2 amyloidosis is likely not rare among Hispanics in the Southwest United States and could represent an important but under-recognized etiology of chronic kidney disease in this population. PMID:26912093

  10. Biafine applied on human epidermal wounds is chemotactic for macrophages and increases the IL-1/IL-6 ratio.

    PubMed

    Coulomb, B; Friteau, L; Dubertret, L

    1997-01-01

    Using a model of pure epidermal wounds in normal human volunteers, we have studied the effects of Biafine emulsion firstly on inflammatory cell migration, vascular permeability and cytokine release during the first 24 h, and secondly on epidermal wound healing by measuring transepidermal water loss from day 1 to day 7. Under these conditions, Biafine does not improve epidermal healing, in contrast to what is observed with bleeding dermoepidermal wounds. Our results suggest that the effects of Biafine are essentially at the dermis level. The analysis of epidermal wound exudates leads to the same conclusion. As a matter of fact, we demonstrated that Biafine is chemotactic for macrophages and increases the IL-1/IL-6 ratio, chiefly by reducing the secretion of IL-6. This study permits to progressively clarify the mode of action of Biafine, that seems to be located at the level of granulation tissue formation and not at the epidermal level. PMID:9449167

  11. Prevalence and organ distribution of leukocyte chemotactic factor 2 amyloidosis (ALECT2) among decedents in New Mexico.

    PubMed

    Larsen, Christopher P; Beggs, Marjorie L; Wilson, Jon D; Lathrop, Sarah L

    2016-06-01

    Leukocyte chemotactic factor 2 (LECT2) amyloidosis is one of the most recently described types of amyloidosis. Since its description, it has been found to be one the most common types of amyloidosis in large series of amyloid cases involving the kidney and liver in the United States, where it primarily affects patients of Hispanic ethnicity. We sought to investigate the prevalence of this disease among Hispanic adult decedents who had an autopsy performed at the New Mexico Office of the Medical Investigator and determine the organ distribution of amyloid deposition. LECT2 amyloid deposits were identified within the kidney in 3.1% of Hispanic decedents. It was consistently deposited in the liver, spleen, adrenals, and lungs but did not involve the myocardium or brain. LECT2 amyloidosis is likely not rare among Hispanics in the Southwest United States and could represent an important but under-recognized etiology of chronic kidney disease in this population. PMID:26912093

  12. Migration of Chemotactic Bacteria Transverse to Flow in Response to a Benzoate Source Plume Created in a Saturated Sand-Packed Microcosm

    NASA Astrophysics Data System (ADS)

    Ford, R.; Boser, B.

    2012-12-01

    Bioremediation processes depend on contact between microbial populations and the groundwater contaminants that they biodegrade. Chemotaxis, the ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, can enhance the transport of bacteria toward contaminant sources that may not be readily accessible by advection and dispersion alone. A two-dimensional rectangular-shaped microcosm packed with quartz sand was used to quantify the effect of chemotaxis on the migration of bacteria within a saturated model aquifer system. Artificial groundwater was pumped through the microcosm at a rate of approximately 1 m/day. A plume of sodium benzoate was created by continuous injection into an upper port of the microcosm to generate a chemical gradient in the vertical direction transverse to flow. Chemotactic bacteria, Pseudomonas putida F1, or the nonchemotactic mutant, P. putida F1 CheA, were injected with a conservative tracer in a port several centimeters below the benzoate position. As the injectates traversed the one-meter length of the microcosm, samples were collected from a dozen effluent ports to determine vertical concentration distributions for the bacteria, benzoate and tracer. A moment analysis was implemented to estimate the center of mass, variance, and skewness of the concentration profiles. The transverse dispersion coefficient and the transverse dispersivity for chemotactic and nonchemotactic bacteria were also evaluated. Experiments performed with a continuous injection of bacteria showed that the center of mass for chemotactic bacteria was closer to the benzoate source on average than the nonchemotactic control (relative to the conservative tracer). These results demonstrated that chemotaxis can increase bacterial transport toward contaminants, potentially enhancing the effectiveness of in situ bioremediation. Experiments with 2 cm and 3 cm spacing between bacteria and benzoate injection locations were

  13. Agent-based model of human alveoli predicts chemotactic signaling by epithelial cells during early Aspergillus fumigatus infection.

    PubMed

    Pollmächer, Johannes; Figge, Marc Thilo

    2014-01-01

    Aspergillus fumigatus is one of the most important human fungal pathogens, causing life-threatening diseases. Since humans inhale hundreds to thousands of fungal conidia every day, the lower respiratory tract is the primary site of infection. Current interaction networks of the innate immune response attribute fungal recognition and detection to alveolar macrophages, which are thought to be the first cells to get in contact with the fungus. At present, these networks are derived from in vitro or in situ assays, as the peculiar physiology of the human lung makes in vivo experiments, including imaging on the cell-level, hard to realize. We implemented a spatio-temporal agent-based model of a human alveolus in order to perform in silico experiments of a virtual infection scenario, for an alveolus infected with A. fumigatus under physiological conditions. The virtual analog captures the three-dimensional alveolar morphology consisting of the two major alveolar epithelial cell types and the pores of Kohn as well as the dynamic process of respiration. To the best of our knowledge this is the first agent-based model of a dynamic human alveolus in the presence of respiration. A key readout of our simulations is the first-passage-time of alveolar macrophages, which is the period of time that elapses until the first physical macrophage-conidium contact is established. We tested for random and chemotactic migration modes of alveolar macrophages and varied their corresponding parameter sets. The resulting first-passage-time distributions imply that randomly migrating macrophages fail to find the conidium before the start of germination, whereas guidance by chemotactic signals derived from the alveolar epithelial cell associated with the fungus enables a secure and successful discovery of the pathogen in time. PMID:25360787

  14. Chemotactic action of prostaglandin E2 on mouse mast cells acting via the PGE2 receptor 3

    PubMed Central

    Weller, Charlotte L.; Collington, Sarah J.; Hartnell, Adele; Conroy, Dolores M.; Kaise, Toshihiko; Barker, Jane E.; Wilson, Mark S.; Taylor, Graham W.; Jose, Peter J.; Williams, Timothy J.

    2007-01-01

    Mast cells are long-lived cells that are principally recognized for their effector function in helminth infections and allergic reactions. These cells are derived from pluripotential hematopoietic stem cells in the bone marrow that give rise to committed mast cell progenitors in the blood and are recruited to tissues, where they mature. Little is known about the chemotactic signals responsible for recruitment of progenitors and localization of mature mast cells. A mouse model was set up to identify possible mast cell progenitor chemoattractants produced during repeated allergen challenge in vivo. After the final challenge, the nasal mucosa was removed to produce conditioned medium, which was tested in chemotaxis assays against 2-wk murine bone marrow-derived c-kit+ mast cells (BMMC). A single peak of chemotactic activity was seen on reverse-phase HPLC with a retention time and electrospray mass spectrum consistent with prostaglandin E2 (PGE2). This lipid was found to be a highly potent chemoattractant for immature (2-wk) and also mature (10-wk) BMMC in vitro. Fluorescently labeled 2-wk c-kit+ BMMC, when injected intravenously, accumulated in response to intradermally injected PGE2. Analysis using TaqMan showed mRNA expression of the PGE2 receptors 3 (EP3) and 4 (EP4) on 2- and 10-wk BMMC. Chemotaxis induced by PGE2 was mimicked by EP3 agonists, blocked by an EP3 receptor antagonist, and partially inhibited by a MAPKK inhibitor. These results show an unexpected function for PGE2 in the chemotaxis of mast cells. PMID:17606905

  15. Effect of "co-ligand" on the biodistribution of 99mTc-labeled hydrazino nicotinic acid derivatized chemotactic peptides.

    PubMed

    Babich, J W; Fischman, A J

    1995-01-01

    Hydrazinonicotinamide (HYNIC) derivatized chemotactic peptides radiolabeled with 99mTc- (via 99mTc-glucoheptonate) have been demonstrated to be useful for infection imaging [J. Nucl. Med. 34, 1964-1974 (1993)]. Since HYNIC can occupy only two sites of the technetium co-ordination sphere, the labeled product most probably contains additional ligands. Thus we hypothesized that glucoheptonate serves this role by acting as a "'co-ligand'". Due to the low molecular weight of the chemotactic peptides, the "co-ligand" used for technetium labeling could have profound effects on biodistribution. To evaluate this possibility, we measured the biodistribution of 99mTc-labeled For-MLFK-HYNIC radiolabeled using four different "co-ligand"s: glucarate, glucoheptonate, mannitol and glucamine, providing a small series of hydroxyl-backbone ligands which differ in the number and type of ionizable functional groups present. Each preparation was injected into groups of 6 rats (approximately 10 microCi/rat) and biodistribution was determined at 5, 30, 60 and 120 min. Although small differences in biodistribution were detected in most tissues, the most prominent differences (P < 0.01) were observed in lung (glucoheptonate, glucarate > mannitol > glucamine), liver (glucarate, glucoheptonate, mannitol > glucamine), kidney (mannitol > glucarate, glucoheptonate, glucamine), spleen (glucarate > glucoheptonate, mannitol > glucamine) and GI-tract (glucarate, glucamine > gluco-heptonate > mannitol). These results provide support for the "co-ligand" hypothesis and indicate that the nature of the "co-ligand" can have profound effects on biodistribution. Although radiolabeling using glucamine as the "co-ligand" results in the lowest concentrations of radioactivity in most organs, the extremely low concentration of mannitol-labeled peptide in the GI-tract suggests that this may be the "co-ligand" of choice for most applications. PMID:7735166

  16. Cofactor Regulation of C5a Chemotactic Activity in Physiological Fluids. Requirement for the Vitamin D Binding Protein, Thrombospondin-1 and its Receptors

    PubMed Central

    Trujillo, Glenda; Zhang, Jianhua; Habiel, David M.; Ge, Lingyin; Ramadass, Mahalakshmi; Ghebrehiwet, Berhane; Kew, Richard R.

    2011-01-01

    Factors in physiological fluids that regulate the chemotactic activity of complement activation peptides C5a and C5a des Arg are not well understood. The vitamin D binding protein (DBP) has been shown to significantly enhance chemotaxis to C5a/C5a des Arg. More recently, platelet-derived thrombospondin-1 (TSP-1) has been shown to facilitate the augmentation of C5a-induced chemotaxis by DBP. The objective of this study was to better characterize these chemotactic cofactors and investigate the role that cell surface TSP-1 receptors CD36 and CD47 may play in this process. The chemotactic activity in C-activated normal serum, citrated plasma, DBP-depleted serum or C5 depleted serum was determined for both normal human neutrophils and U937 cell line transfected with the C5a receptor (U937-C5aR). In addition, levels of C5a des Arg, DBP and TSP-1 in these fluids were measured by RIA or ELISA. Results show that there is a clear hierarchy with C5a being the essential primary signal (DBP or TSP-1 will not function in the absence of C5a), DBP the necessary cofactor and TSP-1 a dependent tertiary factor, since it cannot function to enhance chemotaxis to C5a without DBP. Measurement of the C5a-induced intracellular calcium flux confirmed the same hierarchy observed with chemotaxis. Moreover, analysis of bronchoalveolar lavage fluid (BALF) from patients with the adult respiratory distress syndrome (ARDS) demonstrated that C5a-dependent chemotactic activity is significantly decreased after anti-DBP treatment. Finally, results show that TSP-1 utilizes cell surface receptors CD36 and CD47 to augment chemotaxis, but DBP does not bind to TSP-1, CD36 or CD47. The results clearly demonstrate that C5a/C5a des Arg needs both DBP and TSP-1 for maximal chemotactic activity and suggest that the regulation of C5a chemotactic activity in physiological fluids is more complex than previously thought. PMID:22014686

  17. Extra-chromosomal DNA maintenance in Bacillus subtilis, dependence on flagellation factor FliF and moonlighting mediator EdmS.

    PubMed

    Hakumai, Yuichi; Shimomoto, Kouko; Ashiuchi, Makoto

    2015-05-15

    Extra-chromosomal DNA maintenance (EDM) as an important process in the propagation and genetic engineering of microbes. Bacillus subtilis EdmS (formerly PgsE), a protein comprising 55 amino acids, is a mediator of the EDM process. In this study, the effect of mutation of global regulators on B. subtilis EDM was examined. Mutation of the swrA gene abolished EdmS-mediated EDM. It is known that swrA predominantly regulates expression of the fla/che operon in B. subtilis. We therefore performed EDM analysis using fla/che-deletion mutants and identified an EDM-mediated EDM cooperator in the flgB-fliL region. Further genetic investigation identified the flagellation factor FliF is a crucial EDM cooperator. To our knowledge, this is the first observation of the moonlighting function of FliF in DNA maintenance. PMID:25843804

  18. Elevated monocyte chemotactic proteins 1, 2, and 3 in pulmonary alveolar proteinosis are associated with chemokine receptor suppression.

    PubMed

    Bonfield, Tracey L; John, Nejimol; Malur, Anagha; Barna, Barbara P; Culver, Daniel A; Kavuru, Mani S; Thomassen, Mary Jane

    2005-01-01

    Pulmonary alveolar proteinosis (PAP) is a rare autoimmune lung disease characterized by abnormal surfactant accumulation within alveolar macrophages, and circulating auto-antibodies against granulocyte-macrophage colony stimulating factor (GM-CSF) resulting in functional GM-CSF deficiency. Monocyte/macrophage chemotactic protein-1 (MCP-1) is elevated in PAP, suggesting association with the pathophysiology. Because PAP has been associated with inflammatory pulmonary changes, we hypothesized that other MCP family chemokines would be present and that Chemokine Chemotaxis Receptor 2 (CCR2) would be elevated on PAP mononuclear cells. Here we show for the first time that MCP-2 and MCP-3, like MCP-1, are highly elevated in PAP. We also confirm that PAP alveolar macrophages and not epithelial cells produce MCP-1, and that MCP-1 from PAP lung has functional chemoattractant activity. Surprisingly, CCR2 expression is diminished in PAP lymphocytes and alveolar macrophages compared to controls. Further, MCP-1 from PAP lung suppresses CCR2 expression in vitro, suggesting that in PAP, MCP-1 participates in an autocrine regulatory network in vivo. PMID:15596412

  19. Ultrasensitive electrochemical immunosensor based on orderly oriented conductive wires for the detection of human monocyte chemotactic protein-1 in serum.

    PubMed

    Li, Yuliang; He, Junlin; Xia, Chunyong; Gao, Liuliu; Yu, Chao

    2015-08-15

    For the first time, a simple, ultrasensitive and label-free electrochemical monocyte chemotactic protein-1 (MCP-1) immunosensor based on orderly oriented conductive wires has been developed. A conductive wire, which is similar to an electron-conducting tunnel, was designed with Au nanoparticles (AuNPs) joined to Au@Pt core-shell microspheres via a cysteamine (CA) crosslinker. To enhance the sensitivity of the immunosensor, Au nanoparticles were electrodeposited onto the gold electrode, and CA was self-assembled via strong Au-S covalent bonds, providing an appropriate surface and promoting electron transfer. Next, Au@Pt core-shell microspheres with large surface area were grafted onto the modified electrode to immobilize more MCP-1 antibodies. MCP-1 is an initiating factor and biomarker of atherosclerotic diseases. Under optimal experimental conditions, differential pulse voltammetry (DPV) current changes were used to detect MCP-1 with a broad linear range of 0.09-360 pg mL(-1) and a low detection limit of 0.03 pg mL(-1) (S/N=3). The proposed immunosensor exhibited good selectivity, reproducibility and reusability. When applied to spiked serum samples, the data for the developed immunosensor were in agreement with an enzyme linked immunosorbent assay, suggesting that the electrochemical immunosensor would be suitable for practical detection. PMID:25845330

  20. Plasma Levels of Monocyte Chemotactic Protein-1 Are Associated with Clinical Features and Angiogenesis in Patients with Multiple Myeloma

    PubMed Central

    Valković, Toni; Babarović, Emina; Lučin, Ksenija; Štifter, Sanja; Aralica, Merica; Seili-Bekafigo, Irena; Duletić-Načinović, Antica; Jonjić, Nives

    2016-01-01

    The aim of this pilot study was to determine the plasma levels of monocyte chemotactic protein-1 (MCP-1) and possible associations with angiogenesis and the main clinical features of untreated patients with multiple myeloma (MM). ELISA was used to determine plasma MCP-1 levels in 45 newly diagnosed MM patients and 24 healthy controls. The blood vessels were highlighted by immunohistochemical staining, and computer-assisted image analysis was used for more objective and accurate determination of two parameters of angiogenesis: microvessel density (MVD) and total vascular area (TVA). The plasma levels of MCP-1 were compared to these parameters and the presence of anemia, renal dysfunction, and bone lesions. A significant positive correlation was found between plasma MCP-1 concentrations and TVA (p = 0.02). The MCP-1 levels were significantly higher in MM patients with evident bone lesions (p = 0.01), renal dysfunction (p = 0.02), or anemia (p = 0.04). Therefore, our preliminary results found a positive association between plasma MCP-1 levels, angiogenesis (expressed as TVA), and clinical features in patients with MM. However, additional prospective studies with a respectable number of patients should be performed to authenticate these results and establish MCP-1 as a possible target of active treatment. PMID:26925413

  1. Stromal-derived factor-1α/CXCL12-CXCR4 chemotactic pathway promotes perineural invasion in pancreatic cancer

    PubMed Central

    Xu, Qinhong; Wang, Zheng; Chen, Xin; Duan, Wanxing; Lei, Jianjun; Zong, Liang; Li, Xuqi; Sheng, Liang; Ma, Jiguang; Han, Liang; Li, Wei; Zhang, Lun; Guo, Kun; Ma, Zhenhua; Wu, Zheng; Wu, Erxi; Ma, Qingyong

    2015-01-01

    Perineural invasion (PNI) is considered as an alternative route for the metastatic spread of pancreatic cancer cells; however, the molecular changes leading to PNI are still poorly understood. In this study, we show that the CXCL12/CXCR4 axis plays a pivotal role in the neurotropism of pancreatic cancer cells to local peripheral nerves. Immunohistochemical staining results revealed that CXCR4 elevation correlated with PNI in 78 pancreatic cancer samples. Both in vitro and in vivo PNI models were applied to investigate the function of the CXCL12/CXCR4 signaling in PNI progression and pathogenesis. The results showed that the activation of the CXCL12/CXCR4 axis significantly increased pancreatic cancer cells invasion and promoted the outgrowth of the dorsal root ganglia. CXCL12 derived from the peripheral nerves stimulated the invasion and chemotactic migration of CXCR4-positive cancer cells in a paracrine manner, eventually leading to PNI. In vivo analyses revealed that the abrogation of the activated signaling inhibited tumor growth and invasion of the sciatic nerve toward the spinal cord. These data indicate that the CXCL12/CXCR4 axis may be a novel therapeutic target to prevent the perineural dissemination of pancreatic cancer. PMID:25605248

  2. Characterization of the formyl peptide chemotactic receptor appearing at the phagocytic cell surface after exposure to phorbol myristate acetate

    SciTech Connect

    Gardner, J.P.; Melnick, D.A.; Malech, H.L.

    1986-02-15

    The biochemistry and subcellular source of new formyl peptide chemotactic receptor appearing at the human neutrophil and differentiated HL-60 (d-HL-60) cell surface after stimulation with phorbol myristate acetate (PMA) were examined. Formyl peptide receptor was analyzed by affinity labeling with formyl-norleu-leu-phe-norleu- (/sup 125/I)iodotyr-lys and ethylene glycol bis(succinimidyl succinate) followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and densitometric analysis of autoradiographs. PMA, a specific granule secretagogue, increases affinity labeling of formyl peptide receptors on the neutrophil surface by 100%, and on d-HL-60, which lack specific granule markers, by 20%. Papain treatment markedly reduces surface labeling of formyl peptide receptor in both neutrophils and d-HL-60, and results in the appearance of a lower m.w. membrane-bound receptor fragment. PMA stimulation of papain-treated cells increases uncleaved surface receptor on neutrophils by 400%, and on D-HL-60 by only 45%. This newly appearing receptor is the same apparent m.w. (55,000 to 75,000 for neutrophils; 62,000 to 80,000 for d-HL-60) and yields the same papain cleavage product as receptor on the surface of unstimulated cells. These observations suggest that specific granule membranes contain large amounts of formyl peptide receptor, which is biochemically identical to that found on the cell surface and can be mobilized to the cell surface with appropriate stimulation.

  3. The short form of the CheA protein restores kinase activity and chemotactic ability to kinase-deficient mutants.

    PubMed Central

    Wolfe, A J; Stewart, R C

    1993-01-01

    Escherichia coli expresses two forms of the chemotaxis-associated CheA protein, CheAL and CheAS, as the result of translational initiation at two distinct, in-frame initiation sites in the gene cheA. The long form, CheAL, plays a crucial role in the chemotactic signal transduction mechanism by phosphorylating two other chemotaxis proteins: CheY and CheB. CheAL must first autophosphorylate at amino acid His-48 before transferring its phosphono group to these other signal transduction proteins. The short form, CheAS, lacks the N-terminal 97 amino acids of CheAL and, therefore, does not possess the site of autophosphorylation. Here we demonstrate that although it lacks the ability to autophosphorylate, CheAS can mediate phosphorylation of kinase-deficient variants of CheAL each of which retains a functional autophosphorylation site. This transphosphorylation enables these kinase-deficient CheAL variants to phosphorylate CheY. Because it mediates this activity, CheAS can restore to kinase-deficient E. coli cells the ability to tumble and, thus, to perform chemotaxis in swarm plate assays. Images PMID:8434013

  4. Inhibition of chemiluminescence and chemotactic activity of phagocytes in vitro by the extracts of selected medicinal plants.

    PubMed

    Jantan, Ibrahim; Harun, Nurul Hikmah; Septama, Abdi Wira; Murad, Shahnaz; Mesaik, M A

    2011-04-01

    The methanol extracts of 20 selected medicinal plants were investigated for their effects on the respiratory burst of human whole blood, isolated human polymorphonuclear leukocytes (PMNs) and isolated mice macrophages using a luminol/lucigenin-based chemiluminescence assay. We also tested the effect of the extracts on chemotactic migration of PMNs using the Boyden chamber technique. The extracts of Curcuma domestica L., Phyllanthus amarus Schum & Thonn and C. xanthorrhiza Roxb. were the samples producing the strongest oxidative burst of PMNs with luminol-based chemiluminescence, with IC(50) values ranging from 0.5 to 0.7 μg/ml. For macrophage cells, the extracts which showed strong suppressive activity for luminol-based chemiluminescence were C. xanthorrhiza and Garcinia mangostana L. Among the extracts studied, C. mangga Valton & Vazsjip, Piper nigrum L. and Labisia pumila var. alata showed strong inhibitory activity on lucigenin-amplified oxidative burst of PMNs, with IC(50) values ranging from 0.9 to 1.5 μg/ml. The extracts of Zingiber officinale Rosc., Alpinia galangal (L.) Willd and Averrhoa bilimbi Linn showed strong inhibition on the chemotaxic migration of cells, with IC(50) values comparable to that of ibuprofen (1.5 μg/ml). The results suggest that some of these plants were able to modulate the innate immune response of phagocytes at different steps, emphasizing their potential as a source of new immunomodulatory agents. PMID:21184195

  5. Human neuroblastoma cells express alpha and beta platelet-derived growth factor receptors coupling with neurotrophic and chemotactic signaling.

    PubMed Central

    Matsui, T; Sano, K; Tsukamoto, T; Ito, M; Takaishi, T; Nakata, H; Nakamura, H; Chihara, K

    1993-01-01

    Both platelet-derived growth factor (PDGF) A- and B-chains are expressed in mammalian neurons, but their precise roles still remain to be clarified. In the present studies, we examined the expression of two PDGF receptor genes in human tumor cell lines derived from neural crest. The expression of alpha and/or beta PDGF receptors was detected in a wide variety of neural crest-derived human tumor cell lines such as neuroblastoma, primitive neuroectodermal tumor, and Ewing's sarcoma by RNA blot analysis, and confirmed by immunoblot analysis. We have also demonstrated that PDGF receptors on the human neuroblastoma cell lines were biologically functional. Accordingly, chemotactic and mitogenic activities were induced by either PDGF-AA or PDGF-BB in serum-free medium. PDGF isoforms as well as nerve growth factor induced morphological changes showing neuronal cell maturation. Moreover, PDGF coordinately increased the levels of the transcript of the midsize neurofilament gene. The neuroblastoma cell lines also expressed the transcripts of PDGF A- and B-chains. These findings suggest that PDGF isoforms are involved not only in the promotion of the neuroblastoma cell growth, but also in neuronal cell migration, growth, and differentiation in human brain development. Images PMID:8376577

  6. A novel trypanoplasm-like flagellate Jarrellia atramenti n. g., n. sp. (Kinetoplastida: Bodonidae) and ciliates from the blowhole of a stranded pygmy sperm whale Kogia breviceps (Physeteridae): morphology, life cycle and potential pathogenicity.

    PubMed

    Poynton, S L; Whitaker, B R; Heinrich, A B

    2001-04-10

    The successful 6 mo rehabilitation of a stranded juvenile pygmy sperm whale Kogia breviceps afforded the opportunity to study the poorly known protozoan fauna of the upper respiratory tract of cetaceans. Mucus samples were collected by holding either a petri dish or glass slides over the blowhole for 3 to 5 exhalations; preparations were examined as wet mounts, and then stained with Wrights-Giemsa or Gram stain. Blood smears were stained with Wrights-Giemsa. Unidentified spindle-shaped and unidentified broad ciliates, reported from the blowhole of the pygmy sperm whale for the first time, were seen only initially, while yeast-like organisms and bacteria were seen intermittently. Epithelial cells and white blood cells were often present in the blowhole mucus, but red blood cells were never seen. A novel trypanoplasm-like bodonid kinetoplastid biflagellate (Order Kinetoplastida) was commonly encountered in the blowhole mucus, but never in the blood. Both mature flagellates and those undergoing longitudinal binary fission were present. The elongate flagellate had a long whiplash anterior flagellum; the recurrent flagellum was attached along at least two-thirds of the body length, forming a prominent undulating membrane, and the trailing portion was short. The kinetoplast was irregularly fragmented. The flagellates were either free-swimming, or attached to host material via the free portion of the posterior flagellum. The prominent undulating membrane was characteristic of Trypanoplasma, while the fragmented kinetoplast was characteristic of some species of Cryptobia. For the novel bodonid kinetoplastid, with its unique combination of morphological features (prominent undulating membrane and fragmented kinetoplast), we propose the creation of a new genus Jarrellia. We believe this to be the first published description of a flagellate from a marine mammal, and among the first reports of a trypanoplasm-like flagellate from a warm-blooded host. We expect that a diversity

  7. Monocyte chemotactic protein-1 expression as a prognosic biomarker in patients with solid tumor: a meta analysis

    PubMed Central

    Wang, Hong; Zhang, Qiongwen; Kong, Hongyu; Zeng, Yunhui; Hao, Meiqin; Yu, Ting; Peng, Jing; Xu, Zhao; Chen, Jingquan; Shi, Huashan

    2014-01-01

    Purpose: A great deal of studies have been performed on the prognostic value of monocyte chemotactic protein-1 (MCP-1) in solid tumors in recent years. However, no consistent outcomes are reported. Therefore, the prognostic value of MCP-1 still remains controversial in patients with solid tumors. Here we aimed to evaluate the prognostic value of MCP-1 expression for patients with solid tumors. Methods: Comprehensive literature was selected from PUBMED and EMBASE and clinical studies which reported analysis of survival data about MCP-1 in solid tumors were included. Stata 11.0 was used for performing a meta-analysis on evaluating the relation between MCP-1 and clinical staging, overall survival (OS) and disease free survival (DFS). Results: Eleven studies with a total of 1324 patients with solid tumors were included into our meta-analysis. The result showed that high concentration of MCP-1 was related to a worse OS (HR = 1.95, 95% CI 1.32-2.88). The subgroup analysis on different location of tumors showed that high concentration of MCP-1 meant bad prognosis in patients with digestive cancer (HR = 2.66, 95% CI 1.44-4.91) and urogenital cancer (HR = 2.23, 95% CI 1.61-3.10), even head and neck cancer (HR = 1.99, 95% CI 0.95-4.18) other than respiratory cancer (HR = 1.10, 95% CI 0.39-3.11). Another subgroup analysed on different sites of cancer and indicated a poor prognosis on adenocarcinoma (HR = 2.10, 95% CI 1.63-2.69). Conclusions: Our findings suggest that MCP-1 can be regarded as a poor prognostic maker for solid tumors and may represent important new therapeutic targets. PMID:25120764

  8. Lattice-Boltzmann modeling of contaminant degradation by chemotactic bacteria: exploring the formation and movement of bacterial bands

    NASA Astrophysics Data System (ADS)

    Long, W.; Hilpert, M.

    2008-12-01

    We developed a three-dimensional Lattice-Boltzmann (LB) model to simulate the biodegradation of a dissolved substrate, toward which bacteria exhibit chemotaxis. The model was verified by comparing simulations to capillary assay experiments performed elsewhere. In these assays, a capillary containing an aqueous solution, with initially uniformly distributed dissolved naphthalene, was dipped into a reservoir containing Pseudomonas putida, a microorganism that exhibits chemotaxis to naphthalene. These experiments were also performed with additional glass beads present in the capillary and reservoir. The simulations show that a fraction of the bacteria separates from the reservoir to form a band that moves with constant speed into the capillary while metabolizing the naphthalene. We also used the LB model to explore band formation in a porous medium under groundwater flow conditions. If a bacterial slug is injected, two bacterial bands form; one moves upstream and the other moves downstream. The magnitudes of the two band velocities, as measured relative to the pore-water velocity, are identical. Bacteria injected in excess are advected downstream in a fluid parcel containing no substrate. Our simulations suggest that the bioremediation of a contaminant plume in groundwater can potentially be enhanced by the injection of chemotactic bacteria. We also derived a correlation that predicts the number of bacteria in a band that separates from a semi-infinite bacterial slug in a domain containing substrate that is initially uniformly distributed. This correlation allows estimation of the optimal number of bacteria that needs to be added to a substrate-filled domain, such that the number of bacteria in the band is maximum while simultaneously avoiding the injection of excess bacteria that do not make it into the band.

  9. Lattice-Boltzmann modeling of contaminant degradation by chemotactic bacteria: Exploring the formation and movement of bacterial bands

    NASA Astrophysics Data System (ADS)

    Long, Wei; Hilpert, Markus

    2008-09-01

    We developed a three-dimensional Lattice-Boltzmann (LB) model to simulate the biodegradation of a dissolved substrate, toward which bacteria exhibit chemotaxis. The model was verified by comparing simulations to capillary assay experiments performed elsewhere. In these assays, a capillary containing an aqueous solution, with initially uniformly distributed dissolved naphthalene, was dipped into a reservoir containing Pseudomonas putida, a microorganism that exhibits chemotaxis to naphthalene. These experiments were also performed with additional glass beads present in the capillary and reservoir. The simulations show that a fraction of the bacteria separates from the reservoir to form a band that moves with constant speed into the capillary while metabolizing the naphthalene. We also used the LB model to explore band formation in a porous medium under groundwater flow conditions. If a bacterial slug is injected, two bacterial bands form; one moves upstream and the other moves downstream. The magnitudes of the two band velocities, as measured relative to the pore water velocity, are identical. Bacteria injected in excess are advected downstream in a fluid parcel containing no substrate. Our simulations suggest that the bioremediation of a contaminant plume in groundwater can potentially be enhanced by the injection of chemotactic bacteria. We also derived a correlation that predicts the number of bacteria in a band that separates from a semi-infinite bacterial slug in a domain containing substrate that is initially uniformly distributed. This correlation allows estimation of the optimal number of bacteria that needs to be added to a substrate-filled domain, such that the number of bacteria in the band is maximum while simultaneously avoiding the injection of excess bacteria that do not make it into the band.

  10. Monocyte chemotactic protein-1 deficiency reduces spontaneous metastasis of Lewis lung carcinoma in mice fed a high-fat diet.

    PubMed

    Yan, Lin; Sundaram, Sneha

    2016-04-26

    Adipose-produced pro-inflammatory cytokines contribute to obesity and cancer. This 2x2 experiment was designed to investigate effects of monocyte chemotactic protein-1 (MCP-1) deficiency on pulmonary metastasis of Lewis lung carcinoma (LLC) in MCP-1 deficient and wild-type mice fed a modified AIN93G diet containing 16% and 45% of energy from corn oil, respectively. The high-fat diet significantly increased the number and size (cross-sectional area and volume) of lung metastases compared to the AIN93G control diet. Deficiency in MCP-1 reduced lung metastases by 37% in high-fat diet-fed mice; it reduced metastatic cross-sectional area by 46% and volume by 69% compared to wild-type mice. Adipose and plasma concentrations of MCP-1 were significantly higher in high-fat diet-fed wild-type mice than in their AIN93G-fed counterparts; they were not detectable in MCP-1 deficient mice regardless of diet. Plasma concentrations of plasminogen activator inhibitor-1, tumor necrosis factor-α, vascular endothelial growth factor and tissue inhibitor of metalloproteinase-1 were significantly higher in MCP-1 deficient mice compared to wild-type mice. We conclude that adipose-produced MCP-1 contributes to high-fat diet-enhanced metastasis. While MCP-1 deficiency reduces metastasis, the elevation of pro-inflammatory cytokines and angiogenic factors in the absence of MCP-1 may support the metastatic development and growth of LLC in MCP-1 deficient mice. PMID:27028862

  11. Dose-Response Analysis of Chemotactic Signaling Response in Salmonella typhimurium LT2 upon Exposure to Cysteine / Cystine Redox Pair

    PubMed Central

    2016-01-01

    The chemotaxis system enables motile bacteria to search for an optimum level of environmental factors. Salmonella typhimurium senses the amino acid cysteine as an attractant and its oxidized dimeric form, cystine, as a repellent. We investigated the dose-response dependence of changes in chemotactic signaling activity upon exposure to cysteine and cystine of S. typhimurium LT2 using in vivo fluorescence resonance energy transfer (FRET) measurements. The dose-response curve of the attractant response to cysteine had a sigmoidal shape, typical for receptor-ligand interactions. However, in a knockout strain of the chemoreceptor genes tsr and tar, we detected a repellent response to cysteine solutions, scaling linearly with the logarithm of the cysteine concentration. Interestingly, the magnitude of the repellent response to cystine also showed linear dependence to the logarithm of the cystine concentration. This linear dependence was observed over more than four orders of magnitude, where detection started at nanomolar concentrations. Notably, low concentrations of another oxidized compound, benzoquinone, triggered similar responses. In contrast to S. typhimurium 14028, where no response to cystine was observed in a knockout strain of chemoreceptor genes mcpB and mcpC, here we showed that McpB / McpC-independent responses to cystine existed in the strain S. typhimurium LT2 even at nanomolar concentrations. Additionally, knocking out mcpB and mcpC did not affect the linear dose-response dependence, whereas enhanced responses were only observed to solutions that where not pH neutral (>100 μM cystine) in the case of McpC overexpression. We discuss that the linear dependence of the response on the logarithm of cystine concentrations could be a result of a McpB / C-independent redox-sensing pathway that exists in S. typhimurium LT2. We supported this hypothesis with experiments with defined cysteine / cystine mixed solutions, where a transition from repellent to

  12. Characteristics of attachment and growth of Thiobacillus caldus on sulphide minerals: a chemotactic response to sulphur minerals?

    PubMed

    Edwards, K J; Bond, P L; Banfield, J F

    2000-06-01

    To further our understanding of the ecological role of sulphur-oxidizing microorganisms in the generation of acid mine drainage (AMD), growth and attachment of the chemoautotrophic sulphur-oxidizing bacterium, Thiobacillus caldus, on the sulphide minerals pyrite, marcasite and arsenopyrite was studied. Growth curves were estimated based on total cells detected in the system (in suspension and attached to mineral surfaces). In general, higher cell numbers were detected on surfaces than in suspension. Fluorescent in situ hybridizations to cells on surfaces at mid-log growth confirmed that cells on surfaces were metabolically active. Total cell (both surface and solution phase) generation times on pyrite and marcasite (both FeS2) were calculated to be approximately equals 7 and 6 h respectively. When grown on pyrite (not marcasite), the number of T. caldus cells in the solution phase decreased, while the total number of cells (both surface and solution) increased. Additionally, marcasite supported about three times more total cells (approximately equals 3 x 10(9)) than pyrite (approximately equals 8 x 10(8)). This may be attributed to the dissolution rate of marcasite, which is twice that of pyrite. Epifluorescent and scanning electron microscopy (SEM) were used to analyse the cell orientation on surfaces. Results of Fourier transform analysis of fluorescent images confirmed that attachment to all three sulphides occurred in an oriented manner. Results from high-resolution SEM imaging showed that cell orientation coincides with dissolution pit edges and secondary sulphur minerals that develop during dissolution. Preferential colonization of surfaces relative to solution and oriented cell attachment on these sulphide surfaces suggest that T. caldus may chemotactically select the optimal site for chemoautotrophic growth on sulphur (i.e. the mineral surface). PMID:11200434

  13. Coprophilic amoebae and flagellates, including Guttulinopsis, Rosculus and Helkesimastix, characterise a divergent and diverse rhizarian radiation and contribute to a large diversity of faecal-associated protists.

    PubMed

    Bass, David; Silberman, Jeffrey D; Brown, Matthew W; Pearce, Rebecca A; Tice, Alexander K; Jousset, Alexandre; Geisen, Stefan; Hartikainen, Hanna

    2016-05-01

    A wide diversity of organisms utilize faecal habitats as a rich nutrient source or a mechanism to traverse through animal hosts. We sequenced the 18S rRNA genes of the coprophilic, fruiting body-forming amoeba Guttulinopsis vulgaris and its non-fruiting relatives Rosculus 'ithacus' CCAP 1571/3, R. terrestris n. sp. and R. elongata n. sp. and demonstrate that they are related to the coprophilic flagellate Helkesimastix in a strongly supported, but highly divergent 18S sister clade. PCR primers specific to both clades were used to generate 18S amplicons from a range of environmental and faecal DNA samples. Phylogenetic analysis of the cloned sequences demonstrated a high diversity of uncharacterised sequence types within this clade, likely representing previously described members of the genera Guttulinopsis, Rosculus and Helkesimastix, as well as so-far unobserved organisms. Further, an Illumina MiSeq sequenced set of 18S V4-region amplicons generated from faecal DNAs using universal eukaryote primers showed that core-cercozoan assemblages in faecal samples are as diverse as those found in more conventionally examined habitats. These results reveal many novel lineages, some of which appear to occur preferentially in faecal material, in particular cercomonads and glissomonads. More broadly, we show that faecal habitats are likely untapped reservoirs of microbial eukaryotic diversity. PMID:26914587

  14. Ultrastructure and 18S rDNA sequence analysis of Wobblia lunata gen. et sp. nov., a new heterotrophic flagellate (Stramenopiles, Incertae sedis).

    PubMed

    Moriya, M; Nakayama, T; Inouye, I

    2000-05-01

    A new heterotrophic flagellate Wobblia lunata gen. et sp. nov. is described. This organism usually attaches to the substratum showing a wobbling motion, and sometimes glides on the substratum or swims freely in the medium. W. lunata has various features characteristic of the stramenopiles. These include a hairy flagellum with tripartite tubular hairs, a mitochondrion with tubular cristae, arrangement of flagellar apparatus components and a double helix in the flagellar transition zone. W. lunata shares a double helix with heterotrophic stramenopiles, including Developayella elegans, oomycetes, hyphochytrids, opalinids and proteromonads, and could be placed in the phylum Bigyra Cavalier-Smith. However, from 18S rDNA tree analysis, these organisms form two distantly-related clades in the stramenopiles, and Wobblia appears at the base of the stramenopiles. Evaluation of morphological features and comparison of 18S rDNA sequences indicate that W. lunata is a member of the stramenopiles, but it is distinct from any other stramenopiles so far described. Its phylogenetic position within the stramenopiles is uncertain and therefore W. lunata is described as a stramenopile incertae sedis. PMID:10896132

  15. 'Candidatus Adiutrix intracellularis', an endosymbiont of termite gut flagellates, is the first representative of a deep-branching clade of Deltaproteobacteria and a putative homoacetogen.

    PubMed

    Ikeda-Ohtsubo, Wakako; Strassert, Jürgen F H; Köhler, Tim; Mikaelyan, Aram; Gregor, Ivan; McHardy, Alice C; Tringe, Susannah Green; Hugenholtz, Phil; Radek, Renate; Brune, Andreas

    2016-09-01

    Termite gut flagellates are typically colonized by specific bacterial symbionts. Here we describe the phylogeny, ultrastructure and subcellular location of 'Candidatus Adiutrix intracellularis', an intracellular symbiont of Trichonympha collaris in the termite Zootermopsis nevadensis. It represents a novel, deep-branching clade of uncultured Deltaproteobacteria widely distributed in intestinal tracts of termites and cockroaches. Fluorescence in situ hybridization and transmission electron microscopy localized the endosymbiont near hydrogenosomes in the posterior part and near the ectosymbiont 'Candidatus Desulfovibrio trichonymphae' in the anterior part of the host cell. The draft genome of 'Ca. Adiutrix intracellularis' obtained from a metagenomic library revealed the presence of a complete gene set encoding the Wood-Ljungdahl pathway, including two homologs of fdhF encoding hydrogenase-linked formate dehydrogenases (FDHH ) and all other components of the recently described hydrogen-dependent carbon dioxide reductase (HDCR) complex, which substantiates previous claims that the symbiont is capable of reductive acetogenesis from CO2 and H2 . The close phylogenetic relationship between the HDCR components and their homologs in homoacetogenic Firmicutes and Spirochaetes suggests that the deltaproteobacterium acquired the capacity for homoacetogenesis via lateral gene transfer. The presence of genes for nitrogen fixation and the biosynthesis of amino acids and cofactors indicate the nutritional nature of the symbiosis. PMID:26914459

  16. Effect of a short-term diet and exercise intervention on oxidative stress, inflammation, MMP-9, and monocyte chemotactic activity in men with metabolic syndrome factors.

    PubMed

    Roberts, Christian K; Won, Dean; Pruthi, Sandeep; Kurtovic, Silvia; Sindhu, Ram K; Vaziri, Nosratola D; Barnard, R James

    2006-05-01

    The present study was designed to examine the effects of lifestyle modification on key contributing factors to atherogenesis, including oxidative stress, inflammation, chemotaxis, and cell adhesion. Obese men (n = 31), 15 of whom had metabolic syndrome, were placed on a high-fiber, low-fat diet in a 3-wk residential program where food was provided ad libitum and daily aerobic exercise was performed. In each subject, pre- and postintervention fasting blood was drawn for circulating levels of serum lipids, glucose and insulin (for estimation of insulin sensitivity), oxidative stress-generating enzyme myeloperoxidase and marker 8-isoprostaglandin F2alpha, the inflammatory protein C-reactive protein, soluble ICAM-1 as an indicator of endothelial activation, sP-selectin as a marker of platelet activation, the chemokine macrophage inflammatory protein-1alpha, and total matrix metalloproteinase-9. Using subject sera and human aortic endothelial cell culture systems, we measured VCAM-1 cell surface abundance and monocyte chemotactic protein-1, nitric oxide, superoxide, and hydrogen peroxide production in vitro by fluorometric detection. Also determined in vitro was serum-induced, monocyte adhesion and monocyte chemotactic activity. After 3 wk, significant reductions (P < 0.05) in body mass index, all serum lipids and lipid ratios, fasting glucose, insulin, homeostasis model assessment for insulin resistance, myeloperoxidase, 8-isoprostaglandin F2alpha, C-reactive protein, soluble ICAM-1, soluble P-selectin, macrophage inflammatory protein-1alpha, and matrix metalloproteinase-9 were noted. In vitro, serum-stimulated cellular VCAM-1 expression, monocyte chemotactic protein-1 production, and fluorometric detection of superoxide and hydrogen peroxide production decreased, whereas a concomitant increase in NO production was noted (all P < 0.01). Additionally, both monocyte adhesion (P < 0.05) and MCA (P < 0.01) decreased. Nine of 15 were no longer positive for metabolic

  17. Elevated ex vivo monocyte chemotactic protein-1 (CCL2) in pulmonary as compared with extra-pulmonary tuberculosis

    PubMed Central

    Hasan, Zahra; Zaidi, Irfan; Jamil, Bushra; Khan, M Aslam; Kanji, Akbar; Hussain, Rabia

    2005-01-01

    Background Tuberculosis causes 3 million deaths annually. The most common site of tuberculosis is pulmonary however; extra-pulmonary forms of the disease also remain prevalent. Restriction of Mycobacterium tuberculosis depends on effective recruitment and subsequent activation of T lymphocytes, mononuclear and polymorphonuclear cells to the site of infection. Tumor necrosis factor (TNF)-α is essential for granuloma formation and is a potent activator of monocyte chemotactic protein (MCP-1, CCL2). CCL2 is essential for recruitment of monocytes and T cells and has been shown to play a role in protection against tuberculosis. Interleukin -8 (CXCL8) is a potent activator of neutrophils. Increased levels of CCL2, CXCL8 and TNFα are reported in tuberculosis but their significance in different forms of tuberculosis is as yet unclear. We have used an ex vivo assay to investigate differences in immune parameters in patients with either pulmonary or extra-pulmonary tuberculosis. Methods Serum levels of CCL2, CXCL8 and TNFα were measured in patients with pulmonary tuberculosis (N = 12), extra-pulmonary tuberculosis (N = 8) and BCG-vaccinated healthy volunteers (N = 12). Whole blood cells were stimulated with non-pathogenic Mycobacterium bovis bacille-Calmette Guerin (BCG) vaccine strain or bacterial lipopolysaccharide (LPS) and cyto/chemokines were monitored in supernatants. Results Circulating serum levels of CXCL8 and TNFα were raised in all tuberculosis patients, while CCL2 levels were not. There was no difference in spontaneous cytokine secretion from whole blood cells between patients and controls. M. bovis BCG-induced ex vivo CCL2 secretion was significantly greater in pulmonary as compared with both extra-pulmonary tuberculosis patients and endemic controls. In response to LPS stimulation, patients with pulmonary tuberculosis showed increased CCL2 and TNFα responses as compared with the extra-pulmonary group. BCG-, and LPS-induced CXCL8 secretion was comparable

  18. Critical chemotactic collapse

    NASA Astrophysics Data System (ADS)

    Lushnikov, Pavel M.

    2010-04-01

    A Keller-Segel model describes macroscopic dynamics of bacterial colonies and biological cells as well as dynamics of a gas of self-gravitating Brownian particles. Bacteria secret chemical which attracts other bacteria so that they move towards chemical gradient creating nonlocal attraction between bacteria. If bacterial (or Brownian particle) density exceeds a critical value then the density collapses (blows up) in a finite time which corresponds to bacterial aggregation or gravitational collapse. Collapse in the Keller-Segel model has striking qualitative similarities with a nonlinear Schrödinger equation including critical collapse in two dimensions and supercritical collapse in three dimensions. A self-similar solution near blow up point is studied in the critical two-dimensional case and it has a form of a rescaled steady state solution which contains a critical number of bacteria. Time dependence of scaling of that solution has square root scaling law with logarithmic modification.

  19. Establishment of Azotobacter on plant roots: chemotactic response, development and analysis of root exudates of cotton (Gossypium hirsutum L.) and wheat (Triticum aestivum L.).

    PubMed

    Kumar, Rakesh; Bhatia, Ranjana; Kukreja, K; Behl, Rishi Kumar; Dudeja, Surjit Singh; Narula, Neeru

    2007-10-01

    Biofertilizers contribute in N(2) fixation, P solubilization, phytohormone production and thus enhance plant growth. Beneficial plant-microbe interactions and the stability and effectiveness of biofertilizer depend upon the establishment of bacterial strains in the rhizosphere of the plant. This interaction depends upon many factors, one of them being plant exudates. Root exudates are composed of small organic molecules like carbonic acids, amino acids or sugars etc., which are released into the soil and bacteria can be attracted towards these exudates due to chemotaxis. The chemotactic behaviour of Azotobacter strains was studied using cotton (Desi HD 123 and American H 1098) and wheat (WH 711) seedlings and the root exudates of these two plants were chemically characterized. Analysis of the root exudates revealed the presence of sugars and simple polysaccharides (glucose), amino acids (glutamate, lysine) and organic acids (citric acid, succinic acid, maleic acid, malonic acid). Differences between cotton cultivars in root exudates were observed which influenced chemotactic response in Azotobacter. These results indicate colonization with rhizobacteria which implies that optimal symbionts, on the sides of both plant cultivar and bioinoculant bacteria can lead to better plant growth under cultivation conditions. PMID:17910096

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  1. Tracking Chemotactic Migration of a Genetically Engineered Bacterium in the Presence of Constructed Nutrient Gradients Within a Sandy Aquifer in Cape Cod, Massachusetts

    NASA Astrophysics Data System (ADS)

    Harvey, R. W.; Ford, R. M.; Metge, D. W.; Wang, M.; Toepfer, A. A.; McGowan, S. B.

    2008-05-01

    Due to our increasing dependence upon groundwater resources, there is a growing need to remediate shallow aquifers contaminated with chlorinated solvents. Often, trichloroethene (TCE) travels into zones of low permeability thereby making removal difficult by traditional pump-and-treat technologies. In addition, degradation of TCE by native microbial communities can result in buildup of highly toxic intermediates such as vinyl chloride. Bioaugmentation, involving addition of specialized bacterial consortia to an aquifer, can facilitate more complete degradation into harmless byproducts. Also, it is believed that chemotaxis, the ability of bacteria to swim towards higher concentrations of a chemical perceived as beneficial to survival, may expedite movement of introduced bacteria to where they are needed. However, there is no quantitative information about chemotaxis at the field scale and the evidence for bacterial chemotaxis during bioaugmentation has been largely anecdotal. In this study, the chemotactic migration of the bacterium, Pseudomonas stutzeri in a TCE-contaminated, sand- and-gravel aquifer in Cape Cod, Massachusetts was measured. P. stutzeri is known to denitrify as well as degrade a variety of aromatic and chlorinated solvents and is often advocated as a candidate for bioaugmentation. This bacterium was genetically engineered to be resistant to ampicillin and produce blue- fluorescing protein (BFP) in order to facilitate maintaining the bacteria in pure culture and later to track them in the environment. The study involved a natural-gradient injection and recovery test in which vertical gradients of an electron donor (acetate) and acceptor (nitrate) were created within the sandy aquifer sediments above an amendment of the genetically engineered P. stutzeri. The bacteria, nitrate, and acetate were allowed to be advected with the natural flow of groundwater past close-interval, multi-level samplers that were installed downgradient from the points of

  2. Delivery of platelet-derived growth factor as a chemotactic factor for mesenchymal stem cells by bone-mimetic electrospun scaffolds.

    PubMed

    Phipps, Matthew C; Xu, Yuanyuan; Bellis, Susan L

    2012-01-01

    The recruitment of mesenchymal stem cells (MSCs) is a vital step in the bone healing process, and hence the functionalization of osteogenic biomaterials with chemotactic factors constitutes an important effort in the tissue engineering field. Previously we determined that bone-mimetic electrospun scaffolds composed of polycaprolactone, collagen I and nanohydroxyapatite (PCL/col/HA) supported greater MSC adhesion, proliferation and activation of integrin-related signaling cascades than scaffolds composed of PCL or collagen I alone. In the current study we investigated the capacity of bone-mimetic scaffolds to serve as carriers for delivery of an MSC chemotactic factor. In initial studies, we compared MSC chemotaxis toward a variety of molecules including PDGF-AB, PDGF-BB, BMP2, and a mixture of the chemokines SDF-1α, CXCL16, MIP-1α, MIP-1β, and RANTES. Transwell migration assays indicated that, of these factors, PDGF-BB was the most effective in stimulating MSC migration. We next evaluated the capacity of PCL/col/HA scaffolds, compared with PCL scaffolds, to adsorb and release PDGF-BB. We found that significantly more PDGF- BB was adsorbed to, and subsequently released from, PCL/col/HA scaffolds, with sustained release extending over an 8-week interval. The PDGF-BB released was chemotactically active in transwell migration assays, indicating that bioactivity was not diminished by adsorption to the biomaterial. Complementing these studies, we developed a new type of migration assay in which the PDGF-BB-coated bone-mimetic substrates were placed 1.5 cm away from the cell migration front. These experiments confirmed the ability of PDGF-BB-coated PCL/col/HA scaffolds to induce significant MSC chemotaxis under more stringent conditions than standard types of migration assays. Our collective results substantiate the efficacy of PDGF-BB in stimulating MSC recruitment, and further show that the incorporation of native bone molecules, collagen I and nanoHA, into

  3. Monocyte chemotactic protein-1 (MCP-1) mRNA is down-regulated in human dermal fibroblasts by dexamethasone: differential regulation by TGF-beta.

    PubMed

    Slavin, J; Unemori, E; Hunt, T K; Amento, E

    1995-01-01

    Macrophages are a source of cytokines driving repair. Wound macrophages are derived from circulating monocytes. Monocyte chemotactic protein-1 (MCP-1) is a potent specific monocyte chemoattractant. Treatment of serum stimulated dermal fibroblasts with dexamethasone led to a dose dependent down-regulation of MCP-1 mRNA levels. Such an anti-inflammatory effect may partially explain the negative influence of glucocorticoid treatment on wound repair. Topical or parenteral of fibroblasts cultured in serum free media with TGF-beta increased MCP-1 mRNA levels. TGF-beta treatment of fibroblasts cultured in serum also partially overcame the dexamethasone mediated decrease in MCP-1 mRNA levels. In glucocorticoid treated animals TGF-beta may stimulate repair by an indirect pro-inflammatory action following transcriptional up-regulation of MCP-1. PMID:8679249

  4. Immunity against selected piscine flagellates.

    PubMed

    Woo, Patrick T K; Ardelli, Bernadette F

    2014-04-01

    This discussion is on immune response to Amyloodinium ocellatum, Cryptobia salmositica, Trypanoplasma borreli and Trypanosoma carassii. Piscidin and histone-like proteins enhance innate resistance to Amyloodinium. Fish that are naturally resistant to Cryptobia and Trypanoplasma can be bred. Cryptobia resistance in charr is controlled by a dominant Mendelian locus and protection is via the Alternative Pathway of Complement Activation. Studies on Cryptobia-tolerant charr may lead to production of transgenic Cryptobia-tolerant salmon. Innate response to T. borreli is associated with NO in macrophages. Transferrin regulates resistance and carp have been bred for transferrin genotypes. Recovered fish are protected from homologous challenge, and complement fixing antibodies are crucial in protection. Studies on antigens in T. carassii may lead to a vaccine. There are two vaccines against cryptobiosis; a single dose of the attenuated vaccine protects salmonids. On challenge fish inoculated with the metalloprotease-DNA vaccine do not have the disease and they recover faster. PMID:23872230

  5. MiR-221 and miR-26b Regulate Chemotactic Migration of MSCs Toward HGF Through Activation of Akt and FAK.

    PubMed

    Zhu, Aisi; Kang, Naixin; He, Lihong; Li, Xianyang; Xu, Xiaojing; Zhang, Huanxiang

    2016-06-01

    The chemotactic migration of mesenchymal stem cells (MSCs) is fundamental for their use in cell-based therapies, but little is known about the molecular mechanisms that regulate their directed migration. MicroRNAs (miRNAs) participate in the regulation of a large variety of cellular processes. However, their roles in regulating the responses of MSCs to hepatocyte growth factor (HGF) remain elusive. Here, we found that microRNA-221 (miR-221) and microRNA-26b (miR-26b) were upregulated in MSCs subjected to HGF. Overexpression of miR-221 or miR-26b enhanced MSC migration through activation of PI3K/Akt signaling. Phosphatase and tensin homolog deleted on chromosome ten (PTEN) was identified as a potential target of miR-221 and miR-26b; overexpression of miR-221 or miR-26b decreased PTEN expression at both mRNA and protein levels. Overexpression of miR-221 or miR-26b in MSCs increased the phosphorylation of focal adhesion kinase (FAK), a downstream effector of PTEN, which regulates cell migration through assembly and distribution of focal adhesions (FAs), and more dot-like FAs were localized at the periphery of these cells. Altering miR-221 or miR-26b expression influenced the directed migration of MSCs toward HGF. Inhibition of miR-221 or miR-26b suppressed the phosphorylation of Akt and FAK and upregulated PTEN expression, which was partly restored by HGF treatment. Collectively, these results demonstrate that miR-221 and miR-26b participate in regulating the chemotactic response of MSCs toward HGF. J. Cell. Biochem. 117: 1370-1383, 2016. © 2015 Wiley Periodicals, Inc. PMID:26538296

  6. A dichotomy in cortical actin and chemotactic actin activity between human memory and naive T cells contributes to their differential susceptibility to HIV-1 infection.

    PubMed

    Wang, Weifeng; Guo, Jia; Yu, Dongyang; Vorster, Paul J; Chen, WanJun; Wu, Yuntao

    2012-10-12

    Human memory and naive CD4 T cells can mainly be identified by the reciprocal expression of the CD45RO or CD45RA isoforms. In HIV-1 infection, blood CD45RO memory CD4 T cells are preferentially infected and serve as a major viral reservoir. The molecular mechanism dictating this differential susceptibility to HIV-1 remains largely obscure. Here, we report that the different susceptibility of memory and naive T cells to HIV is not determined by restriction factors such as Apobec3G or BST2. However, we observed a phenotypic distinction between human CD45RO and CD45RA resting CD4 T cells in their cortical actin density and actin dynamics. CD45RO CD4 T cells possess a higher cortical actin density and can be distinguished as CD45RO(+)Actin(high). In contrast, CD45RA T cells are phenotypically CD45RA(+)Actin(low). In addition, the cortical actin in CD45RO memory CD4 T cells is more dynamic and can respond to low dosages of chemotactic induction by SDF-1, whereas that of naive cells cannot, despite a similar level of the chemokine receptor CXCR4 present on both cells. We further demonstrate that this difference in the cortical actin contributes to their differential susceptibility to HIV-1; resting memory but not naive T cells are highly responsive to HIV-mediated actin dynamics that promote higher levels of viral entry and early DNA synthesis in resting memory CD4 T cells. Furthermore, transient induction of actin dynamics in resting naive T cells rescues HIV latent infection following CD3/CD28 stimulation. These results suggest a key role of chemotactic actin activity in facilitating HIV-1 latent infection of these T cell subsets. PMID:22879601

  7. Natural Killer (NK)/melanoma cell interaction induces NK-mediated release of chemotactic High Mobility Group Box-1 (HMGB1) capable of amplifying NK cell recruitment

    PubMed Central

    Parodi, Monica; Pedrazzi, Marco; Cantoni, Claudia; Averna, Monica; Patrone, Mauro; Cavaletto, Maria; Spertino, Stefano; Pende, Daniela; Balsamo, Mirna; Pietra, Gabriella; Sivori, Simona; Carlomagno, Simona; Mingari, Maria Cristina; Moretta, Lorenzo; Sparatore, Bianca; Vitale, Massimo

    2015-01-01

    In this study we characterize a new mechanism by which Natural Killer (NK) cells may amplify their recruitment to tumors. We show that NK cells, upon interaction with melanoma cells, can release a chemotactic form of High Mobility Group Box-1 (HMGB1) protein capable of attracting additional activated NK cells. We first demonstrate that the engagement of different activating NK cell receptors, including those mainly involved in tumor cell recognition can induce the active release of HMGB1. Then we show that during NK-mediated tumor cell killing two HMGB1 forms are released, each displaying a specific electrophoretic mobility possibly corresponding to a different redox status. By the comparison of normal and perforin-defective NK cells (which are unable to kill target cells) we demonstrate that, in NK/melanoma cell co-cultures, NK cells specifically release an HMGB1 form that acts as chemoattractant, while dying tumor cells passively release a non-chemotactic HMGB1. Finally, we show that Receptor for Advanced Glycation End products is expressed by NK cells and mediates HMGB1-induced NK cell chemotaxis. Proteomic analysis of NK cells exposed to recombinant HMGB1 revealed that this molecule, besides inducing immediate chemotaxis, also promotes changes in the expression of proteins involved in the regulation of the cytoskeletal network. Importantly, these modifications could be associated with an increased motility of NK cells. Thus, our findings allow the definition of a previously unidentified mechanism used by NK cells to amplify their response to tumors, and provide additional clues for the emerging role of HMGB1 in immunomodulation and tumor immunity. PMID:26587323

  8. A paracrine role for chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2) in mediating chemotactic activation of CRTH2+ CD4+ T helper type 2 lymphocytes.

    PubMed

    Vinall, Shân L; Townsend, Elizabeth R; Pettipher, Roy

    2007-08-01

    Activation of human CRTH2(+) CD4(+) T helper type 2 (Th2) cells with anti-CD3/anti-CD28 led to time-dependent production of prostaglandin D(2) (PGD(2)) which peaked at 8 hr. The production of PGD(2) was completely inhibited by cotreatment with the cyclo-oxygenase inhibitor diclofenac (10 microm) but was not affected by cotreatment with ramatroban, a dual antagonist of both the thromboxane-like prostanoid (TP) receptor and the chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). Supernatants from activated CRTH2(+) CD4(+) Th2 cells caused a concentration-dependent increase in the migration of naive CRTH2(+) CD4(+) Th2 cells compared to supernatants from unstimulated CRTH2(+) CD4(+) Th2 cells. The level of chemotactic activity peaked at 8 hr after activation, corresponding to the peak levels of PGD(2), but production of chemotactic activity was only partially inhibited by the cyclo-oxygenase inhibitor diclofenac. In contrast, ramatroban completely inhibited the chemotactic responses of naive Th2 cells to supernatants from activated CRTH2(+) CD4(+) Th2 cells collected up to 8 hr after activation, although supernatants collected 24 hr after activation were less sensitive to inhibition by ramatroban. The selective TP antagonist SQ29548 did not inhibit migration of Th2 cells, implicating CRTH2 in this response. These data suggest that CRTH2 plays an important paracrine role in mediating chemotactic activation of Th2 cells. Interestingly, although PGD(2) is produced from Th2 cells and contributes to this paracrine activation, it appears that additional CRTH2 agonist factors are also produced by activated Th2 cells and the production of these factors occurs independently of the cyclo-oxygenase pathway of the arachidonic acid metabolism. PMID:17437532

  9. Osteopontin, a chemotactic protein with cytokine-like properties, is up-regulated in muscle injury caused by Bothrops lanceolatus (fer-de-lance) snake venom.

    PubMed

    Barbosa-Souza, Valéria; Contin, Daniel Kiss; Filho, Waldemar Bonventi; de Araújo, Albetiza Lôbo; Irazusta, Silvia Pierre; da Cruz-Höfling, Maria Alice

    2011-10-01

    Osteopontin (OPN) is a chemotactic, adhesive protein whose receptors include some integrins and matrix proteins known to have role in inflammatory and repair processes. We examined the time course of OPN expression at acute and chronic stages after intramuscular injection of Bothrops lanceolatus venom in rats. Additionally, we examined the expression of CD68 (a marker for phagocytic macrophages) and the myogenic factors, myoD and myogenin. There was a biphasic upregulation of OPN (6-48 h and 3-14 days post-venom), i.e., during acute inflammation and myogenic cell proliferation and differentiation phases. OPN was detected in CD68 + macrophages, fibroblasts, normal and damaged myofibers, myoblasts and myotubes. Myogenin was expressed in the cytoplasm (atypical pattern) and nucleus of myoblasts and myotubes from 18 h to 7 days, after which it was expressed only in nuclei. Macrophage numbers, OPN and myogenin expression were still elevated at 7, 14 and 7 days. At 3 days, when OPN achieved the peak, some clusters of myoblasts were within regions of intense collagen deposition. Fibrosis may represent limitation for repairing processes and may explain the small diameter of regenerated fibers at 21 days post-venom. The expression of OPN in the course of venom-induced damage and regeneration suggests stages-specific mediation role along the whole process. PMID:21839764

  10. Urantide improves atherosclerosis by controlling C-reactive protein, monocyte chemotactic protein-1 and transforming growth factor-β expression in rats

    PubMed Central

    ZHAO, JUAN; XIE, LI-DE; SONG, CHENG-JUN; MAO, XIAO-XIA; YU, HAI-RONG; YU, QUAN-XIN; REN, LI-QUN; SHI, YAN; XIE, YA-QIN; LI, YING; LIU, SHA-SHA; YANG, XIAO-HONG

    2014-01-01

    The aim of the present study was to investigate the effects of urantide on the expression status of C-reactive protein (CRP) and the inflammatory cytokines monocyte chemotactic protein (MCP)-1 and transforming growth factor (TGF)-β in the aortas of rats with atherosclerosis (AS), and to identify its underlying mechanisms. The effects of urantide in a rat model of AS and in cultured rat vascular smooth muscle cells (VSMCs) were analyzed via hematoxylin and eosin staining, immunohistochemical staining and ELISA. The results in vivo demonstrated that urantide downregulated the expression of inflammatory mediators CRP and MCP-1 and upregulated the expression of TGF-β. The results in vitro indicated that urantide inhibited the proliferation of VSMCs. In addition, urantide reduced the expression of CRP and downregulated the secretion of TGF-β in the culture supernatant. In conclusion, urantide ameliorated the arterial inflammatory damage that was observed in the AS rat model at the cell and tissue levels by controlling the expression of CRP and the inflammatory cytokines MCP-1 and TGF-β. Therefore, urantide may be a potential agent for the complementary treatment of AS. PMID:24926360

  11. Chemotactic and enzyme-releasing activity of amphipathic proteins for neutrophils. A possible role for protease in chemotaxis on substratum-bound protein gradients.

    PubMed Central

    Wilkinson, P C; Bradley, G R

    1981-01-01

    The purified amphipathic proteins, alpha s 1-casein, beta-casein, and alkali-denatured serum albumin were studied for chemotactic and enzyme-releasing effects on human neutrophil leucocytes. Evidence for chemotaxis both in fluid-phase gradients and on solid-phase gradients was obtained using visual assays. In fluid-phase gradients, neutrophils showed good orientation to gradient sources of these proteins at concentrations of 10(-4) to 10(-5) M. Solid-phase gradients of casein and of denatured albumin were prepared on glass coverslips, and the locomotion of neutrophils attached to these coverslips was filmed by time-lapse cinematography. Displacement of neutrophils towards the highest concentration of substratum-bound protein was observed, suggesting that neutrophils can show true chemotaxis on a solid-phase gradient. All three proteins induced enzyme release from neutrophils in the absence of cytochalasin B. Lysozyme release was equivalent to that released by stimulation with formyl methionyl peptide in the presence of cytochalasin B, but the proteins stimulated a smaller release of beta-glucuronidase than the peptide. The proteins stimulated release of neutrophil proteases which were able to digest both casein and denatured albumin extracellularly. It is suggested that this proteolytic activity may assist locomotion of neutrophils, especially on solid-phase protein gradients, by cleaving membrane-attached protein, thus both freeing cell-surface receptors and allowing the cell to detach itself from the substratum and continue movement. Images Figure 1 PMID:7016748

  12. Macrophage-derived neutrophil chemotactic factor is involved in the neutrophil recruitment inhibitory activity present in the supernatants of LPS-stimulated macrophages

    PubMed Central

    Tavares-Murta, B. M.; Cunha, F. Q.; Dias-Baruffi, M.; Roque-Barreira, M. C.

    1996-01-01

    In a previous study, we demonstrated the presence of a neutrophil recruitment inhibitory factor (NRIF) in the supernatants of LPS-stimulated macrophages. Recently, the purification of a 54 kDa protein, identified as the macrophage-derived neutrophil chemotactic factor (MNCF) was reported. Since NRIF and MNCF are obtained under the same conditions, and, since the intravenous administration of TNF-α and IL-8 inhibits neutrophil migration, we have investigated whether MNCF could be responsible for this inhibitory activity. After affinity chromatography of the macrophage supernatants on a D-galactose column, the inhibitory activity was recovered in both the unbound (D-gal−) and bound (D-gal+) fractions, with MNCF being found in the D-gal+ fraction. Further gel filtration of the latter on Superdex 75 yielded a single peak containing both activities. In a cytotoxicity assay, most of the TNF found in the crude supernatants was recovered in the D-gal− fraction. Furthermore, the incubation of the D-gal− fraction with anti-TNF-α plus anti-IL-8 antisera partially prevents its inhibitory effect on neutrophil migration, but had no effect on the D-gal+ activity. Overall, these results suggest that the D-gal− inhibitory effect is partially mediated by TNF-α and IL-8, and that MNCF accounts for the inhibition of neutrophil migration in vivo by the D-gal+ fraction. PMID:18475709

  13. Evidence for Widespread Epithelial Damage and Coincident Production of Monocyte Chemotactic Protein 1 in a Murine Model of Intestinal Ricin Intoxication▿

    PubMed Central

    Yoder, J. Marina; Aslam, Rabia U.; Mantis, Nicholas J.

    2007-01-01

    The development of small-animal models is necessary to understand host responses and immunity to emerging infectious diseases and potential bioterrorism agents. In this report we have characterized a murine model of intestinal ricin intoxication. Ricin administered intragastrically (i.g.) to BALB/c mice at doses ranging from 1 to 10 mg/kg of body weight induced dose-dependent morphological changes in the proximal small intestine (i.e., duodenum), including widespread villus atrophy and epithelial damage. Coincident with epithelial damage was a localized increase in monocyte chemotactic protein 1, a chemokine known to be associated with inflammation of the intestinal mucosa. Immunity to intestinal ricin intoxication was achieved by immunizing mice i.g. with ricin toxoid and correlated with elevated levels of antitoxin mucosal immunoglobulin A (IgA) and serum IgG antibodies. We expect that this model will serve as a valuable tool in identifying the inflammatory pathways and protective immune responses that are elicited in the intestinal mucosa following ricin exposure and will prove useful in the evaluation of antitoxin vaccines and therapeutics. PMID:17283086

  14. Role of Urinary Levels of Endothelin-1, Monocyte Chemotactic Peptide-1, and N-Acetyl Glucosaminidase in Predicting the Severity of Obstruction in Hydronephrotic Neonates

    PubMed Central

    Rafiei, Alireza; Mousavi, Seyed Abdollah; Alaee, Abdulrasool; Yeganeh, Yalda

    2014-01-01

    Purpose Antenatal hydronephrosis (AH) is found in 0.5%-1% of neonates. The aim of the study was to assess the urinary concentrations of 3 biomarkers, endothelin-1 (ET-1), monocyte chemotactic peptide-1 (MCP-1), and N-acetyl-glucosaminidase (NAG) in severely hydronephrotic neonates. Materials and Methods Neonates with a history of prenatal hydronephrosis were enrolled in the prospective study in 2 groups. Group 1 included neonates with severe forms of obstruction requiring surgical intervention and group 2 included neonates with milder forms of obstruction without any functional impairment. Fresh voided urinary levels of ET-1, MCP-1, and NAG were measured and their ratios to urinary Cr were calculated. Results Fourty-two neonates were enrolled into the 2 groups: group 1, 24 patients (21 male, 3 female); group 2, 18 neonates (16 male, 2 female). There were no statistically significant differences between urinary ET-1, NAG, MCP-1 values, and ET-1/Cr and NAG/Cr ratios in groups 1 and 2. The urinary MCP-1/Cr ratio was significantly higher in group 1 than in group 2. For comparison of groups 1 and 2, the cut-off values were measured as 0.5709 ng/mg (sensitivity, 75%; specificity, 67%; positive predictive value [PPV], 71%; negative predictive value [NPV], 71%), 0.927 ng/mg (sensitivity, 77%; specificity, 72%; PPV, 77%; NPV, 72%), and 1.1913 IU/mg (sensitivity, 62%; specificity, 67%; PPV, 68%; NPV, 60%) for ET-1/Cr, MCP-1/Cr, and NAG/Cr ratios, respectively. Conclusions The urinary MCP-1/Cr ratio is significantly elevated in neonates with severe obstruction requiring surgical intervention. Based upon these results, urinary MCP-1/Cr may be useful in identification of severe obstructive hydronephrosis in neonates. PMID:25324951

  15. Expression, oxidative refolding, and characterization of six-histidine-tagged recombinant human LECT2, a 16-kDa chemotactic protein with three disulfide bonds.

    PubMed

    Ito, Mie; Nagata, Koji; Kato, Yusuke; Oda, Yoshifumi; Yamagoe, Satoshi; Suzuki, Kazuo; Tanokura, Masaru

    2003-02-01

    Human LECT2 is a 16-kDa chemotactic protein that consists of 133 amino acids and three intramolecular disulfide bonds. Here, we present the oxidative refolding of (His)(6)-LECT2, an N-terminally (His)(6)-tagged recombinant protein of human LECT2. (His)(6)-LECT2 was overproduced in Escherichia coli in the form of insoluble aggregates, solubilized with 8 M urea in the presence of 10 mM DTT, and purified and refolded on Ni-NTA agarose by lowering the urea concentration before the elution. This process, however, gave a mixture of oligomers of (His)(6)-LECT2 as well as the monomer, whose composition was as low as 36%. The oligomers formed as a result of incorrect intermolecular disulfide bonds. After the refolding on Ni-NTA agarose (step 1), the disulfide bonds were shuffled using a glutathione redox buffer (step 2) and the remaining thiols were completely oxidized (step 3) to improve the yield of correctly folded, monomeric (His)(6)-LECT2. The monomer composition was significantly improved to 81% by the three-step refolding method and the monomer thus obtained was shown to have the same conformation as the authentic LECT2 produced in CHO cells by CD and NMR spectroscopies. The yield of (His)(6)-LECT2 was 1.0 mg/L E. coli culture and was 16 times as high as that in our previous report, in which (His)(6)-LECT2 was purified from the soluble fractions of E. coli cell lysates. PMID:12597887

  16. Monocyte Chemotactic Protein-1, Fractalkine, and Receptor for Advanced Glycation End Products in Different Pathological Types of Lupus Nephritis and Their Value in Different Treatment Prognoses

    PubMed Central

    Lan, Lan; Han, Fei; Lang, Xiabing; Chen, Jianghua

    2016-01-01

    Background Early diagnosis is important for the outcome of lupus nephritis (LN). However, the pathological type of lupus nephritis closely related to the clinical manifestations; therefore, the treatment of lupus nephritis depends on the different pathological types. Objective To assess the level of monocyte chemotactic protein (MCP-1), fractalkine (Fkn), and receptor for advanced glycation end product (RAGE) in different pathological types of lupus nephritis and to explore the value of these biomarkers for predicting the prognosis of lupus nephritis. Methods Patients included in this study were assessed using renal biopsy. Class III and class IV were defined as the proliferative group, class V as non-proliferative group, and class V+III and class V+IV as the mixed group. During the follow-up, 40 of 178 enrolled patients had a poor response to the standard immunosuppressant therapy. The level of markers in the different response groups was tested. Results The levels of urine and serum MCP-1, urine and serum fractalkine, and serum RAGE were higher in the proliferative group, and lower in the non-proliferative group, and this difference was significant. The levels of urine and serum MCP-1 and serum RAGE were lower in the poor response group, and these differences were also significant. The relationship between urine MCP-1 and urine and serum fractalkine with the systemic lupus erythematosus disease activity index was evaluated. Conclusion The concentration of cytokines MCP-1, fractalkine, and RAGE may be correlated with different pathology type of lupus nephtitis. Urine and serum MCP-1 and serum RAGE may help in predicting the prognosis prior to standard immunosuppressant therapy. PMID:27458981

  17. The G2019S LRRK2 mutation increases myeloid cell chemotactic responses and enhances LRRK2 binding to actin-regulatory proteins

    PubMed Central

    Moehle, Mark S.; Daher, João Paulo Lima; Hull, Travis D.; Boddu, Ravindra; Abdelmotilib, Hisham A.; Mobley, James; Kannarkat, George T.; Tansey, Malú G.; West, Andrew B.

    2015-01-01

    The Leucine rich repeat kinase 2 (LRRK2) gene is genetically and biochemically linked to several diseases that involve innate immunity. LRRK2 protein is highly expressed in phagocytic cells of the innate immune system, most notably in myeloid cells capable of mounting potent pro-inflammatory responses. Knockdown of LRRK2 protein in these cells reduces pro-inflammatory responses. However, the effect of LRRK2 pathogenic mutations that cause Parkinson's disease on myeloid cell function is not clear but could provide insight into LRRK2-linked disease. Here, we find that rats expressing G2019S LRRK2 have exaggerated pro-inflammatory responses and subsequent neurodegeneration after lipopolysaccharide injections in the substantia nigra, with a marked increase in the recruitment of CD68 myeloid cells to the site of injection. While G2019S LRRK2 expression did not affect immunological homeostasis, myeloid cells expressing G2019S LRRK2 show enhanced chemotaxis both in vitro in two-chamber assays and in vivo in response to thioglycollate injections in the peritoneum. The G2019S mutation enhanced the association between LRRK2 and actin-regulatory proteins that control chemotaxis. The interaction between G2019S LRRK2 and actin-regulatory proteins can be blocked by LRRK2 kinase inhibitors, although we did not find evidence that LRRK2 phosphorylated these interacting proteins. These results suggest that the primary mechanism of G2019S LRRK2 with respect to myeloid cell function in disease may be related to exaggerated chemotactic responses. PMID:25926623

  18. Urinary kidney injury molecule-1 and monocyte chemotactic protein-1 are noninvasive biomarkers of cisplatin-induced nephrotoxicity in lung cancer patients

    PubMed Central

    Shinke, Haruka; Masuda, Satohiro; Togashi, Yousuke; Ikemi, Yasuaki; Ozawa, Aiko; Sato, Tomoko; Kim, Young Hak; Mishima, Michiaki; Ichimura, Takaharu; Bonventre, Joseph V.; Matsubara, Kazuo

    2015-01-01

    Purpose Acute kidney injury (AKI) is a common and serious adverse effect of cisplatin-based chemotherapy. However, traditional markers of kidney function, such as serum creatinine, are suboptimal, because they are not sensitive measures of proximal tubular injury. We aimed to determine whether the new urinary biomarkers such as kidney injury molecule-1 (KIM-1), monocyte chemotactic protein-1 (MCP-1), and neutrophil gelatinase-associated lipocalin (NGAL) could detect cisplatin-induced AKI in lung cancer patients in comparison with the conventional urinary proteins such as N-acetyl-β-D-glucosaminidase (NAG) and β2-microglobulin. Methods We measured KIM-1, MCP-1, NGAL, NAG and β2-microglobulin concentrations in urine samples from 11 lung cancer patients, which were collected the day before cisplatin administration and on days 3, 7, and 14. Subsequently, we evaluated these biomarkers by comparing their concentrations in 30 AKI positive (+) and 12 AKI negative (−) samples and performing receiver operating characteristic (ROC) curve analyses. Results The urinary levels normalized with urine creatinine of KIM-1 and MCP-1, but not NGAL, NAG and β2-microglobulin in AKI (+) samples were significantly higher than those in AKI (−) samples. In addition, ROC curve analyses revealed that KIM-1 and MCP-1, but not NGAL, could detect AKI with high accuracy (area under the curve [AUC] = 0.858, 0.850, and 0.608, respectively). The combination of KIM-1 and MCP-1 outperformed either biomarker alone (AUC = 0.871). Conclusions Urinary KIM-1 and MCP-1, either alone or in combination, may represent biomarkers of cisplatin-induced AKI in lung cancer patients. PMID:26407820

  19. MONOCYTE CHEMOTACTIC PROTEIN AND RESPONSE TO PEGYLATED INTERFERON-ALPHA-2A TREATMENT IN PATIENTS WITH CHRONIC HEPATITIS C (CHC) GENOTYPE 4.

    PubMed

    Mohamed, Amal A; Sayed, Ola; Ali, Omnia E; Sayed, Ghadir A; Moustfa, Zainab; Elagawy, Waleed Ahmed

    2016-04-01

    The prevalence of hepatitis C virus (HCV) infection varies across the world, with the highest number of infections reported in Egypt. Monocyte chemotactic protein-1 (MCP-1) is a potent chemokine, and its hepatic expression is up-regulated during chronic HCV infection. Fifty naive patients with chronic hepatitis C in National Hepatology & Tropical Medicine Research Institute and 20 healthy volunteers as controls were enrolled in a prospective study designed with strict inclusion criteria to nullify the effect of confounding variables and further minimize selection bias. Fifty naive patients were treated with PEG-IFN-a2b, at a dose of 1801 g/kg subcutaneously every week plus ribavirin at a dose of 1000- 1200 mg/day, according to the patient's body weight, for 48 weeks. Quantification of HCV-RNA by real-time PCR and MCP-1 by ELISA were performed for every patient and controls. There was a sta- tistically significant difference between patients and control group as regards the quantity of MCP-1 (P < 0.05) (Mann-Whitney test) (P = 0.004). There was a significant difference between responders and nonresponses regarding MCP-1 (P < 0.05), responders showed a higher percentage of cases with initial MCP-1 < 306 (P < 0.05). We conclude the importance of the detection of MCP-1 expression at the start of therapy as a factor for assessing the likelihood of HCV genotype 4 patients to achieving a sustained virological response to treatment with IFN-a2 in combination with ribavirin. PMID:27363047

  20. Beneficial effects of the naturally occurring flavonoid silibinin on the prostate cancer microenvironment: role of monocyte chemotactic protein-1 and immune cell recruitment.

    PubMed

    Ting, Harold; Deep, Gagan; Kumar, Sushil; Jain, Anil K; Agarwal, Chapla; Agarwal, Rajesh

    2016-06-01

    Tumor microenvironment plays an essential role in prostate carcinogenesis and offers novel opportunities to prevent and treat prostate cancer (PCA). Here, we investigated the ability of cancer-associated fibroblasts (CAFs) to promote PCA progression, and silibinin efficacy to target this response. We collected conditioned media from CAFs treated with vehicle or silibinin, and labeled as control conditioned media (CCM) or silibinin-treatment conditioned media (SBCM), respectively. Next, we characterized the effect of CCM and SBCM treatment in several PCA cell lines (RWPE-1, WPE-1 NA-22, WPE-1 NB-14 and PC3). Result showed that compared with SBCM, CCM significantly reduces E-cadherin expression and increases invasiveness and clonogenicity in PCA cells. Further molecular studies identified monocyte chemotactic protein-1 (MCP-1) as the key component of CCM that promotes PCA invasiveness, whereas silibinin treatment strongly reduced MCP-1 expression in CAFs by inhibiting the DNA-binding activity of MCP-1 transcriptional regulators-nuclear factor-kappaB and AP-1. In vivo, silibinin feeding (200mg/kg body weight) strongly reduced TRAMPC1 allografts growth (by 68%) in syngeneic C57Bl/6 mice. TRAMPC1 tumor analysis showed that silibinin reduced MCP-1 and CAFs' biomarkers (fibroblast activation protein, α-smooth muscle actin, transforming growth factor beta 2, vimentin etc.) and significantly modulated the recruitment of immune cells in the tumor microenvironment. Similar inhibitory effects of silibinin on MCP-1 and immune cells recruitment were also observed in TRAMP PCA tissues with reported silibinin efficacy. Overall, our data suggest that silibinin can target CAF-mediated invasiveness in PCA by inhibiting MCP-1 secretion. This, in turn, was associated with a reduction in immune cell recruitment in vivo along with a marked reduction in tumor growth. PMID:27207648

  1. Inhibitory effects of resveratrol on foam cell formation are mediated through monocyte chemotactic protein-1 and lipid metabolism-related proteins.

    PubMed

    Dong, Wenpeng; Wang, Xianyue; Bi, Shenghui; Pan, Zhiguo; Liu, Shenxi; Yu, Hao; Lu, Hua; Lin, Xi; Wang, Xiaowu; Ma, Tao; Zhang, Weida

    2014-05-01

    Resveratrol has been shown to exert anti-atherosclerotic effects. 5' AMP-activated protein kinase (AMPK) and monocyte chemotactic protein-1 (MCP-1) play key roles in foam cell formation, which is considered as the initiation of atherosclerosis. Thus, in this study, we investigated whether resveratrol inhibits foam cell formation by regulating lipid accumulation and inflammation. For this purpose, THP-1 cells were treated with 100 nM phorbol 12-myristate 13-acetate (PMA) to induce their differentiation into macrophages. The macrophages were then pre-treated with 2.5 µM resveratrol and subsequently with serum-free (SF) medium alone or SF medium containing lipopolysaccharide (LPS; 100 ng/ml) and oxidized low-density lipoprotein (ox-LDL; 50 µg/ml) for 24 h to detect foam cell formation. To detect the expression of lipid accumulation-related proteins, the macrophages were treated with resveratrol. For the detection MCP-1 expression, the macrophages were treated with LPS and resveratrol, or with resveratrol alone. We incubated the THP-1-derived macrophages in resveratrol (2.5 µM) for 6 h in the presence or absence of 30 µM compound C for 4 h to detect the influence of compound C on the effects of resveratrol. The foam cells were examined using Red O staining. Gene expression levels were determined by qRT-PCR, western blot analysis and ELISA; lipid analysis was carried out by high-performance liquid chromatography (HPLC). The results revealed that resveratrol effectively suppressed foam cell formation induced by LPS. Resveratrol also suppressed lipid accumulation and downregulated the mRNA expression of peroxisome proliferator-activated receptor (PPAR)γ and PPARα, but had no effect on the expression of PPARβ/δ. Resveratrol also upregulated the expression of AMPK and Silent information regulator T1 (SIRT1). However, the effects of resveratrol on SIRT1, PPARγ and PPARα expression and lipid accumulation were reversed when the cells were pre-treated with compound C

  2. Comparison of acute toxicity of process chemicals used in the oil refinery industry, tested with the diatom Chaetoceros gracilis, the flagellate Isochrysis galbana, and the zebra fish, Brachydanio rerio

    SciTech Connect

    Roseth, S.; Edvardsson, T.; Botten, T.M.; Fuglestad, J.; Fonnum, F.; Stenersen, J.

    1996-07-01

    Chemicals under the trade names Nalco 537-DA, Nalco 625, Nalco 7607, Nalco 5165, Ivamin, and technical monoethanolamine are used extensively in the oil refinery industry. Aquatic toxicity tests were conducted using zebra fish fry (Brachydanio rerio) and the unicellular algae Isochrysis galbana (a flagellate) and Chaetoceros gracilis (a diatom). Inhibition of cell division, chlorophyll content, and {sup 14}CO{sub 2} uptake in the algae were sensitive end points. The effective concentrations (EC50s) of growth inhibition were 0.1 mg/L (Ivamin; I. galbana), 0.8 mg/L (Nalco 7607; I. galbana), 6 mg/L (Nalco 625; I. galbana), 10 mg/L (Nalco 5165; C. gracilis), and 15 mg/L (Nalco 537-DA; C. gracilis). The lethal concentrations (LC50s) (96 h) toward zebra fish fry was 1 mg/L for Nalco 7607, 6.5 mg/L for Nalco 537-DA, 7.1 mg/L for Nalco 625, and 20 mg/L for Ivamin 803. Monoethanolamine had an LC50 higher than 5,000 mg/L. Nalco 5165 was not tested on fish fry. The heartbeat frequency of fish embryos was reduced by 2.5 mg/L Nalco 537-DA, but this was an insensitive end point for the other chemicals.

  3. Maze Solving by Chemotactic Droplets

    SciTech Connect

    Lagzi, Istvan; Soh, Siowling; Wesson, Paul J.; Browne, Kevin P.; Grzybowski, Bartosz A.

    2010-01-11

    Droplets emitting surface-active chemicals exhibit chemotaxis toward low-pH regions. Such droplets are self-propelled and navigate through a complex maze to seek a source of acid placed at one of the maze’s exits. In doing so, the droplets find the shortest path through the maze. Chemotaxis and maze solving are due to an interplay between acid/base chemistry and surface tension effects.

  4. Activation of superoxide formation and lysozyme release in human neutrophils by the synthetic lipopeptide Pam3Cys-Ser-(Lys)4. Involvement of guanine-nucleotide-binding proteins and synergism with chemotactic peptides.

    PubMed Central

    Seifert, R; Schultz, G; Richter-Freund, M; Metzger, J; Wiesmüller, K H; Jung, G; Bessler, W G; Hauschildt, S

    1990-01-01

    Upon exposure to the bacterial chemotactic peptide fMet-Leu-Phe, human neutrophils release lysozyme and generate superoxide anions (O2.-). The synthetic lipoamino acid N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteine (Pam3Cys), which is derived from the N-terminus of bacterial lipoprotein, when attached to Ser-(Lys)4 [giving Pam3Cys-Ser-(Lys)4], activated O2.- formation and lysozyme release in human neutrophils with an effectiveness amounting to about 15% of that of fMet-Leu-Phe. Palmitic acid, muramyl dipeptide, lipopolysaccharide and the lipopeptides Pam3Cys-Ala-Gly, Pam3Cys-Ser-Gly, Pam3Cys-Ser, Pam3Cys-OMe and Pam3Cys-OH did not activate O2.- formation. Pertussis toxin, which ADP-ribosylates guanine-nucleotide-binding proteins (G-proteins) and functionally uncouples formyl peptide receptors from G-proteins, prevented activation of O2.- formation by fMet-Leu-Phe and inhibited Pam3Cys-Ser-(Lys)4-induced O2.- formation by 85%. Lipopeptide-induced exocytosis was pertussis-toxin-insensitive. O2.- formation induced by Pam3Cys-Ser-(Lys)4 and fMet-Leu-Phe was enhanced by cytochalasin B, by a phorbol ester and by a diacylglycerol kinase inhibitor. Addition of activators of adenylate cyclase and removal of extracellular Ca2+ inhibited O2.- formation by fMet-Leu-Phe and Pam3Cys-Ser-(Lys)4 to different extents. Pam3Cys-Ser-(Lys)4 synergistically enhanced fMet-Leu-Phe-induced O2.- formation and primed neutrophils to respond to the chemotactic peptide at non-stimulatory concentrations. Our data suggest the following. (1) Pam3Cys-Ser-(Lys)4 activates neutrophils through G-proteins, involving pertussis-toxin-sensitive and -insensitive processes. (2) The signal transduction pathways activated by fMet-Leu-Phe and Pam3Cys-Ser-(Lys)4 are similar but not identical. (3) In inflammatory processes, bacterial lipoproteins and chemotactic peptides may interact synergistically to activate O2.- formation, leading to enhanced bactericidal activity. PMID:2160237

  5. ORF3 of Hepatitis E Virus Inhibits the Expression of Proinflammatory Cytokines and Chemotactic Factors in LPS-Stimulated Human PMA-THP1 Cells by Inhibiting NF-κB Pathway.

    PubMed

    Lei, Qingsong; Li, Lin; Cai, Jia; Huang, Wenxiang; Qin, Bo; Zhang, Shujun

    2016-03-01

    Hepatitis E virus (HEV) is one of the primary causative agents of acute hepatitis. It is noteworthy that HEV can develop chronic infection and even lead to liver cirrhosis; however, the mechanism has not been revealed. In this study, the ELISA assay was used to detect protein levels, and we found that HEV open reading frame 3 (ORF3) protein inhibited the expression of proinflammatory cytokines (tumor necrosis factor-alpha [TNF-α], interleukin [IL]-1β, IL-6, IL-8, IL-12p40, and IL-18) and chemotactic factors (nitric oxide [NO], interferon-inducible protein-10 (IP-10), macrophage inflammatory protein (MIP)-1α, monocyte chemoattractant protein-1 (MCP-1), granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF)] in lipopolysaccharide (LPS)-stimulated human PMA-THP1 cells. Further study showed that mRNA and protein levels of pattern recognition receptors (PRRs), such as Toll-like receptor 4 (TLR4), TNF receptor-associated factor 6 (TRAF6), and nucleotide-binding oligomerization domain containing 2 (NOD2), decreased after infection of pLL3.7-ORF3 (pORF3); moreover, the inhibition produced corresponding upregulation of IκBα and downregulation of phosphorylated IκB kinase IKKɛ (p-IKKɛ) and phosphorylated nuclear factor (NF)-κB (p-NF-κB), but little variation was found in the concentration of IKKɛ and NF-κB. Taken together, our results demonstrated that HEV ORF3 attenuated LPS-induced cytokine production and chemotactic factors, predominantly by inhibiting various PRRs-mediated NF-κB signaling pathways. The anti-inflammatory properties might be of great importance to clarify the role and mechanism of macrophages in chronic HEV infection and cirrhosis. PMID:26771290

  6. Rhodopsin-Mediated Photoreception in Cryptophyte Flagellates

    PubMed Central

    Sineshchekov, Oleg A.; Govorunova, Elena G.; Jung, Kwang-Hwan; Zauner, Stefan; Maier, Uwe-G.; Spudich, John L.

    2005-01-01

    We show that phototaxis in cryptophytes is likely mediated by a two-rhodopsin-based photosensory mechanism similar to that recently demonstrated in the green alga Chlamydomonas reinhardtii, and for the first time, to our knowledge, report spectroscopic and charge movement properties of cryptophyte algal rhodopsins. The marine cryptophyte Guillardia theta exhibits positive phototaxis with maximum sensitivity at 450 nm and a secondary band above 500 nm. Variability of the relative sensitivities at these wavelengths and light-dependent inhibition of phototaxis in both bands by hydroxylamine suggest the involvement of two rhodopsin photoreceptors. In the related freshwater cryptophyte Cryptomonas sp. two photoreceptor currents similar to those mediated by the two sensory rhodopsins in green algae were recorded. Two cDNA sequences from G. theta and one from Cryptomonas encoding proteins homologous to type 1 opsins were identified. The photochemical reaction cycle of one Escherichia-coli-expressed rhodopsin from G. theta (GtR1) involves K-, M-, and O-like intermediates with relatively slow (∼80 ms) turnover time. GtR1 shows lack of light-driven proton pumping activity in E. coli cells, although carboxylated residues are at the positions of the Schiff base proton acceptor and donor as in proton pumping rhodopsins. The absorption spectrum, corresponding to the long-wavelength band of phototaxis sensitivity, makes this pigment a candidate for one of the G. theta sensory rhodopsins. A second rhodopsin from G. theta (GtR2) and the one from Cryptomonas have noncarboxylated residues at the donor position as in known sensory rhodopsins. PMID:16150961

  7. How bacteria maintain location and number of flagella?

    PubMed

    Schuhmacher, Jan S; Thormann, Kai M; Bange, Gert

    2015-11-01

    Bacteria differ in number and location of their flagella that appear in regular patterns at the cell surface (flagellation pattern). Despite the plethora of bacterial species, only a handful of these patterns exist. The correct flagellation pattern is a prerequisite for motility, but also relates to biofilm formation and the pathogenicity of disease-causing flagellated bacteria. However, the mechanisms that maintain location and number of flagella are far from being understood. Here, we review our knowledge on mechanisms that enable bacteria to maintain their appropriate flagellation pattern. While some peritrichous flagellation patterns might occur by rather simple stochastic processes, other bacterial species appear to rely on landmark systems to define the designated flagellar position. Such landmarks are the Tip system of Caulobacter crescentus or the signal recognition particle (SRP)-GTPase FlhF and the MinD/ParA-type ATPase FlhG (synonyms: FleN, YlxH and MinD2). The latter two proteins constitute a regulatory circuit essential for diverse flagellation patterns in many Gram-positive and negative species. The interactome of FlhF/G (e.g. C-ring proteins FliM, FliN, FliY or the transcriptional regulator FleQ/FlrA) seems evolutionary adapted to meet the specific needs for a respective pattern. This variability highlights the importance of the correct flagellation pattern for motile species. PMID:26195616

  8. Taxonomy of Aerobic Marine Eubacteria

    PubMed Central

    Baumann, Linda; Baumann, Paul; Mandel, M.; Allen, Richard D.

    1972-01-01

    Two hundred and eighteen strains of nonfermentative marine bacteria were submitted to an extensive morphological, physiological, and nutritional characterization. All the strains were gram-negative, straight or curved rods which were motile by means of polar or peritrichous flagella. A wide variety of organic substrates served as sole sources of carbon and energy. The strains differed extensively in their nutritional versatility, being able to utilize from 11 to 85 carbon compounds. Some strains had an extracellular amylase, gelatinase, lipase, or chitinase and were able to utilize n-hexadecane and to denitrify. None of the strains had a yellow, cell-associated pigment or a constitutive arginine dihydrolase system, nor were they able to hydrolyze cellulose or agar. The results of the physiological and nutritional characterization were submitted to a numerical analysis which clustered the strains into 22 groups on the basis of phenotypic similarities. The majority of these groups were separable by a large number of unrelated phenotypic traits. Analysis of the moles per cent guanine plus cytosine (GC) content in the deoxyribonucleic acid of representative strains indicated that the peritrichously flagellated groups had a GC content of 53.7 to 67.8 moles%; polarly flagellated strains had a GC content of 30.5 to 64.7 moles%. The peritrichously flagellated groups were assigned to the genus Alcaligenes. The polarly flagellated groups, which had a GC content of 43.2 to 48.0 moles%, were placed into a newly created genus, Alteromonas; groups which had a GC content of 57.8 to 64.7 moles% were placed into the genus Pseudomonas; and the remaining groups were left unassigned. Twelve groups were given the following designations: Alteromonas communis, A. vaga, A. macleodii, A. marinopraesens, Pseudomonas doudoroffi, P. marina, P. nautica, Alcaligenes pacificus, A. cupidus, A. venustus, and A. aestus. The problems of assigning species of aerobic marine bacteria to genera are

  9. Taxonomy of aerobic marine eubacteria.

    PubMed

    Baumann, L; Baumann, P; Mandel, M; Allen, R D

    1972-04-01

    Two hundred and eighteen strains of nonfermentative marine bacteria were submitted to an extensive morphological, physiological, and nutritional characterization. All the strains were gram-negative, straight or curved rods which were motile by means of polar or peritrichous flagella. A wide variety of organic substrates served as sole sources of carbon and energy. The strains differed extensively in their nutritional versatility, being able to utilize from 11 to 85 carbon compounds. Some strains had an extracellular amylase, gelatinase, lipase, or chitinase and were able to utilize n-hexadecane and to denitrify. None of the strains had a yellow, cell-associated pigment or a constitutive arginine dihydrolase system, nor were they able to hydrolyze cellulose or agar. The results of the physiological and nutritional characterization were submitted to a numerical analysis which clustered the strains into 22 groups on the basis of phenotypic similarities. The majority of these groups were separable by a large number of unrelated phenotypic traits. Analysis of the moles per cent guanine plus cytosine (GC) content in the deoxyribonucleic acid of representative strains indicated that the peritrichously flagellated groups had a GC content of 53.7 to 67.8 moles%; polarly flagellated strains had a GC content of 30.5 to 64.7 moles%. The peritrichously flagellated groups were assigned to the genus Alcaligenes. The polarly flagellated groups, which had a GC content of 43.2 to 48.0 moles%, were placed into a newly created genus, Alteromonas; groups which had a GC content of 57.8 to 64.7 moles% were placed into the genus Pseudomonas; and the remaining groups were left unassigned. Twelve groups were given the following designations: Alteromonas communis, A. vaga, A. macleodii, A. marinopraesens, Pseudomonas doudoroffi, P. marina, P. nautica, Alcaligenes pacificus, A. cupidus, A. venustus, and A. aestus. The problems of assigning species of aerobic marine bacteria to genera are

  10. Rapid intracellular calcium changes in U937 monocyte cell line: transient increases in response to platelet-activating factor and chemotactic peptide but not interferon-gamma or lipopolysaccharide.

    PubMed

    Maudsley, D J; Morris, A G

    1987-06-01

    The dye fura-2, a potentially more sensitive successor to quin2 for measuring intracellular free calcium ion concentrations [(Ca2+]i), has been applied here to investigate the possible involvement of early changes in [Ca2+]i in the stimulation of the human monocyte-macrophage-like cell line U937. The calcium ionophores A23187 and ionomycin, known pharmacological stimuli for macrophages, were found to cause sharp rises in [Ca2+]i as expected. Responses analogous to those reported for a murine macrophage cell (J774) were obtained on stimulation of U937 cells with ATP which caused rapid, but transient, increases in [Ca2+]i (from resting levels of about 70 nM to peaks of about 200 mM). In addition to ATP, several agents known to activate macrophages were used as stimuli. In particular, platelet-activating factor (PAF; 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) was found to cause rapid, but transient, increases in [Ca2+]i (from resting levels of about 70 nM to peaks of about 400 nM) even at concentrations as low as 10(-10) M. This contrasts with responses to ATP that were markedly reduced at 10(-6) M compared with 10(-5) M or above, suggesting that PAF is a highly potent stimulus for intracellular calcium mobilization in macrophages. Similar responses were obtained with chemotactic peptide (N-formyl-methionyl-leucyl-phenylalanine). On the other hand, two agents known to be potent activators of macrophages, interferon gamma and lipopolysaccharide, had no rapid effect on [Ca2+]i. This may reflect differences in the kinetics of signal-response coupling or alternatively a different mechanism of action by-passing the need for rapid elevation of [Ca2+]i. PMID:3110054

  11. Profiling Signaling Polarity in Chemotactic Cells

    SciTech Connect

    Wang, Yingchun; Ding, Shi-Jian; Wang, Wei; Jacobs, Jon M.; Qian, Weijun; Moore, Ronald J.; Yang, Feng; Camp, David G.; Smith, Richard D.; Klemke, Richard L.

    2007-05-15

    While directional movement requires morphological polarization characterized by formation of a leading pseudopodium at the front and a trailing rear at the back, little is known about how protein networks are spatially integrated to regulate this process. Here, we utilize a unique pseudopodial purification system and quantitative proteomics and phosphoproteomics to map the spatial relationship of 3509 proteins and 228 distinct sites of phosphorylation in polarized cells. Networks of signaling proteins, metabolic pathways, actin regulatory proteins, and kinase-substrate cascades were found to partition to different poles of the cell including components of the Ras/ERK pathway. Also, several novel proteins were found to be differentially phosphorylated at the front or rear of polarized cells and to localize to distinct subcellular structures. Our findings provide insight into the spatial organization of signaling networks that control cell movement and provide a comprehensive profile of proteins and their sites of phosphorylation that control cell polarization.

  12. Chemotactic Signaling by Single-Chain Chemoreceptors

    PubMed Central

    Mowery, Patricia; Ames, Peter; Reiser, Rebecca H.; Parkinson, John S.

    2015-01-01

    Bacterial chemoreceptors of the methyl-accepting chemotaxis protein (MCP) family operate in commingled clusters that enable cells to detect and track environmental chemical gradients with high sensitivity and precision. MCP homodimers of different detection specificities form mixed trimers of dimers that facilitate inter-receptor communication in core signaling complexes, which in turn assemble into a large signaling network. The two subunits of each homodimeric receptor molecule occupy different locations in the core complexes. One subunit participates in trimer-stabilizing interactions at the trimer axis, the other lies on the periphery of the trimer, where it can interact with two cytoplasmic proteins: CheA, a signaling autokinase, and CheW, which couples CheA activity to receptor control. As a possible tool for independently manipulating receptor subunits in these two structural environments, we constructed and characterized fused genes for the E. coli serine chemoreceptor Tsr that encoded single-chain receptor molecules in which the C-terminus of the first Tsr subunit was covalently connected to the N-terminus of the second with a polypeptide linker. We showed with soft agar assays and with a FRET-based in vivo CheA kinase assay that single-chain Tsr~Tsr molecules could promote serine sensing and chemotaxis responses. The length of the connection between the joined subunits was critical. Linkers nine residues or shorter locked the receptor in a kinase-on state, most likely by distorting the native structure of the receptor HAMP domain. Linkers 22 or more residues in length permitted near-normal Tsr function. Few single-chain molecules were found as monomer-sized proteolytic fragments in cells, indicating that covalently joined receptor subunits were responsible for mediating the signaling responses we observed. However, cysteine-directed crosslinking, spoiling by dominant-negative Tsr subunits, and rearrangement of ligand-binding site lesions revealed subunit swapping interactions that will need to be taken into account in experimental applications of single-chain chemoreceptors. PMID:26709829

  13. Regulation of chemotactic networks by 'atypical' receptors.

    PubMed

    Comerford, Iain; Litchfield, Wendel; Harata-Lee, Yuka; Nibbs, Robert J B; McColl, Shaun R

    2007-03-01

    Directed cell migration is a fundamental component of numerous biological systems and is critical to the pathology of many diseases. Although the importance of secreted chemoattractant factors in providing navigational cues to migrating cells bearing specific chemoattractant receptors is now well-established, how the function of these factors is regulated is not so well understood and may be of key importance to the design of new therapeutics for numerous human diseases. While regulation of migration clearly takes place on a number of different levels, it is becoming clear that so-called 'atypical' receptors play a role in scavenging, or altering the localisation of, chemoattractant molecules such as chemokines and complement components. These receptors do this through binding and/or internalising their chemoattractant ligands without activating signal transduction cascades leading to cell migration. The atypical chemokine receptor family currently comprises the receptors D6, DARC and CCX-CKR. In this review, we discuss the evidence from in vitro and in vivo studies that these receptors play a role in regulating cell migration, and speculate that other orphan receptors may also belong to this family. Furthermore, with the advent of gene therapy on the horizon, the therapeutic potential of these receptors in human disease is also considered. PMID:17295321

  14. Suppression of Chemotactic Explosion by Mixing

    NASA Astrophysics Data System (ADS)

    Kiselev, Alexander; Xu, Xiaoqian

    2016-06-01

    Chemotaxis plays a crucial role in a variety of processes in biology and ecology. In many instances, processes involving chemical attraction take place in fluids. One of the most studied PDE models of chemotaxis is given by the Keller-Segel equation, which describes a population density of bacteria or mold which is attracted chemically to substance they secrete. Solutions of the Keller-Segel equation can exhibit dramatic collapsing behavior, where density concentrates positive mass in a measure zero region. A natural question is whether the presence of fluid flow can affect singularity formation by mixing the bacteria thus making concentration harder to achieve. In this paper, we consider the parabolic-elliptic Keller-Segel equation in two and three dimensions with an additional advection term modeling ambient fluid flow. We prove that for any initial data, there exist incompressible fluid flows such that the solution to the equation stays globally regular. On the other hand, it is well known that when the fluid flow is absent, there exists initial data leading to finite time blow up. Thus the presence of fluid flow can prevent the singularity formation. We discuss two classes of flows that have the explosion arresting property. Both classes are known as very efficient mixers. The first class are the relaxation enhancing (RE) flows of (Ann Math:643-674, 2008). These flows are stationary. The second class of flows are the Yao-Zlatos near-optimal mixing flows (Mixing and un-mixing by incompressible flows. arXiv:1407.4163, 2014), which are time dependent. The proof is based on the nonlinear version of the relaxation enhancement construction of (Ann Math:643-674, 2008), and on some variations of the global regularity estimate for the Keller-Segel model.

  15. Description of a bacterium associated with redmouth disease of rainbow trout (Salmo gairdneri)

    USGS Publications Warehouse

    1966-01-01

    A description was given of a gram-negative, peritrichously flagellated, fermentative bacterium that was isolated on numerous occasions from kidney tissues of rainbow trout (Salmo gairdneri) afflicted with redmouth disease. Although the bacteria apparently were members of the family Enterobacteriaceae, it was impossible to determine their taxonomic position within the family with certainty. Hence it was recommended that their taxonomic position remain sub judice for the present. As a temporary designation RM bacterium was used. Redmouth disease was transmitted from infected to normal fish through the medium of water.

  16. Computational and experimental study of chemotaxis of an ensemble of bacteria attached to a microbead.

    PubMed

    Traoré, Mahama A; Sahari, Ali; Behkam, Bahareh

    2011-12-01

    Micro-objects propelled by whole cell actuators, such as flagellated bacteria, are being increasingly studied and considered for a wide variety of applications. In this work we present theoretical and experimental investigations of chemotactic motility of a 10 μm diameter microbead propelled by an ensemble of attached flagellated bacteria. The stochastic model presented here encompasses the behavior of each individual bacterium attached to the microbead in a spatiotemporally varying chemoattractant field. The computational model shows that in a chemotactic environment, the ensemble of bacteria, although constrained, propel the bead in a chemotactic manner with a 67% enhancement in displacement to distance ratio (defined as directionality) compared to nonchemotactic propulsion. The simulation results are validated experimentally. Close agreement between theory and experiments demonstrates the possibility of using the presented model as a predictive tool for other similar biohybrid systems. PMID:22304117

  17. In vitro culture of the flagellate protozoan Hexamita salmonis

    USGS Publications Warehouse

    Uzmann, J.R.; Hayduk, S.H.

    1963-01-01

    Trophozoites of Hexamita salmonis, asserted pathogen of juvenile salmonid fishes, were isolated from two species of Pacific salmon hosts and cultured repeatedly in an organic medium saturated with nitrogen. Primary isolates and serial subcultures usually exhibited five- to tenfold population increases per passage.

  18. Waltzing Volvox/: Orbiting Bound States of Flagellated Multicellular Algae

    NASA Astrophysics Data System (ADS)

    Drescher, K.; Leptos, K.; Pedley, T. J.; Goldstein, R. E.; Ishikawa, T.

    2008-11-01

    The spherical colonial alga Volvox swims by means of flagella on thousands of surface somatic cells. This geometry and its large size makes it a model organism for the fluid dynamics of multicellularity. Remarkably, when two nearby colonies swim close to a solid surface, they are attracted together and can form a stable bound state in which they continuously waltz around each other. A surface-mediated hydrodynamic attraction between colonies combined with the rotational motion of bottom-heavy Volvox are shown to explain the stability and dynamics of the bound state. This phenomenon is suggested to underlie observed clustering of colonies at surfaces.

  19. Flagellates as model system for gravity detection of single cells

    NASA Astrophysics Data System (ADS)

    Lebert, Michael; Richter, Peter; Daiker, Viktor; Schuster, Martin; Tebart, Jenny; Strauch, Sebastian M.; Donat-Peter, H.

    Euglena gracilis is a unicellular, photosynthetic organism which uses light and gravity as en-vironmental hints to reach and stay in horizons of the water column which are optimal for growth and reproduction. The orientation in respect to light (so called positive and nega-tive phototaxis, i.e. movement toward or away of a light source) was well known and fairly good understood. In contrast, knowledge about the movement away from the centre of gravity (negative gravitaxis) was rather scarce. Over a century it was unclear whether orientation in respect to the gravity vector is based on a physical or a physiological mechanism. Recent results clearly favour the latter. Knock-down mutants (RNAi) were characterized which define certain key components of the gravitactic signal transduction chain. These key components include a TRP-like channel, a gravitaxis-specific calmodulin and a protein kinase A. The molecular characterization of these components is currently performed and will be presented. Euglena is not only a model system for the close understanding of gravity detection in single cells, but can also be used as photosynthetic component, i.e. oxygen source and carbon dioxide as well as nitrogenic components sink in Closed Environmental Systems (CES). Due CES are systems of choice in times of scarce flight opportunities. They allow a massive sample sharing and combine possibilities to do microgravity research for biologists but also for engineers, physicists and material scientists. Recent attempts include Aquacells and Omegahab. In the near future miniaturized systems (Chinese ShenZhou) as well as advanced CES will be flown or tested, respectively. Current attempts and plans will be presented.

  20. The Cc Chemokine Thymus-Derived Chemotactic Agent 4 (Tca-4, Secondary Lymphoid Tissue Chemokine, 6ckine, Exodus-2) Triggers Lymphocyte Function–Associated Antigen 1–Mediated Arrest of Rolling T Lymphocytes in Peripheral Lymph Node High Endothelial Venules

    PubMed Central

    Stein, Jens V.; Rot, Antal; Luo, Yi; Narasimhaswamy, Manjunath; Nakano, Hideki; Gunn, Michael D.; Matsuzawa, Akio; Quackenbush, Elizabeth J.; Dorf, Martin E.; von Andrian, Ulrich H.

    2000-01-01

    T cell homing to peripheral lymph nodes (PLNs) is defined by a multistep sequence of interactions between lymphocytes and endothelial cells in high endothelial venules (HEVs). After initial tethering and rolling via L-selectin, firm adhesion of T cells requires rapid upregulation of lymphocyte function–associated antigen 1 (LFA-1) adhesiveness by a previously unknown pathway that activates a Gαi-linked receptor. Here, we used intravital microscopy of murine PLNs to study the role of thymus-derived chemotactic agent (TCA)-4 (secondary lymphoid tissue chemokine, 6Ckine, Exodus-2) in homing of adoptively transferred T cells from T-GFP mice, a transgenic strain that expresses green fluorescent protein (GFP) selectively in naive T lymphocytes (TGFP cells). TCA-4 was constitutively presented on the luminal surface of HEVs, where it was required for LFA-1 activation on rolling TGFP cells. Desensitization of the TCA-4 receptor, CC chemokine receptor 7 (CCR7), blocked TGFP cell adherence in wild-type HEVs, whereas desensitization to stromal cell–derived factor (SDF)-1α (the ligand for CXC chemokine receptor 4 [CXCR4]) did not affect TGFP cell behavior. TCA-4 protein was not detected on the luminal surface of PLN HEVs in plt/plt mice, which have a congenital defect in T cell homing to PLNs. Accordingly, TGFP cells rolled but did not arrest in plt/plt HEVs. When TCA-4 was injected intracutaneously into plt/plt mice, the chemokine entered afferent lymph vessels and accumulated in draining PLNs. 2 h after intracutaneous injection, luminal presentation of TCA-4 was detectable in a subset of HEVs, and LFA-1–mediated TGFP cell adhesion was restored in these vessels. We conclude that TCA-4 is both required and sufficient for LFA-1 activation on rolling T cells in PLN HEVs. This study also highlights a hitherto undocumented role for chemokines contained in afferent lymph, which may modulate leukocyte recruitment in draining PLNs. PMID:10620605

  1. In vivo and in vitro chemotactic methylation in Bacillus subtilis.

    PubMed Central

    Ullah, A H; Ordal, G W

    1981-01-01

    Two doublets of Bacillus subtilis membrane proteins with molecular weights of 69,000 and 71,000 and of 30,000 and 30,800, were labeled by C3H3 transfer in the absence of protein synthesis. In addition, there was intense methylation of several low-molecular-weight substances. Both doublets were missing in a chemotaxis mutant. The equivalent proteins in Escherichia coli and Salmonella typhimurium are believed to be the methyl-accepting chemotaxis proteins. The higher-molecular-weight doublet bands were increased in degree of methylation upon addition of attractant to the bacteria. A methyltransferase from B. subtilis that methylates the wild-type membrane significantly better than the mutant membrane, using S-adenosylmethionine, has been partly purified. The methylated product was alkali labile and is probably a gamma-glutamyl methyl ester, as in E. coli and S. typhimurium. Ca2+ ion inhibited the methyltransferase, with a Ki of about 80 nM. Analysis of the in vitro methylation product showed labeling of the 69,000-dalton methyl-accepting chemotaxis protein and a low-molecular-weight protein, using wild-type membrane. Labeling of the low-molecular-weight protein but not of the 69,000 dalton protein was observed when the mutant membrane was used. The chemotaxis mutant tumbled much longer than the wild type when diluted away from attractant. Images PMID:6780537

  2. The macrophage chemotactic activity of Edwardsiella tarda extracellular products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemoattractant capabilities of Edwardsiella tarda extracellular products (ECP) were investigated from two isolates, the virulent FL6-60 parent and less virulent RET-04 mutant. Chemotaxis and chemokinesis were assayed in vitro using blind well chambers with peritoneal macrophages obtained from ...

  3. Chemotactic response of Flavobacterium columnare to channel catfish mucus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research has demonstrated that genomovar II Flavobacterium columnare isolates are more pathogenic for channel catfish (Ictalurus punctatus) and have a higher capacity for adhesion than genomovar I isolates. To begin to define the basis for this, the objectives of the present study were to determine...

  4. Characterization and phylogenetic identification of a species of spherical multicellular magnetotactic prokaryotes that produces both magnetite and greigite crystals.

    PubMed

    Zhang, Rui; Chen, Yi-Ran; Du, Hai-Jian; Zhang, Wen-Yan; Pan, Hong-Miao; Xiao, Tian; Wu, Long-Fei

    2014-09-01

    Magnetotactic bacteria (MTB) are a group of Gram-negative bacteria synthesizing magnetic crystals that allow them aligning along magnetic field lines. They have diverse morphologies including cocci, rods, vibrio, spirilla, and multicellular magnetotactic prokaryotes (MMPs). MMPs are composed of 10-57 cells with peritrichous flagella on their outer surfaces and swim as an entire unit. Here, we describe a species of spherical MMPs isolated from intertidal sediments of Lake Yuehu (Yellow Sea, China). They were mainly found in the subsurface layer of gray-black sediments. Microscopy revealed that these spherical MMPs were 5.6 ± 0.9 μm in diameter and composed of approximately 16-32 ovoid cells with a helical arrangement and peritrichous flagellation. High-resolution transmission electron microscopy showed that the MMPs contained both bullet-shaped magnetite and irregular greigite magnetosomes that were arranged in chains or clusters. These MMPs displayed typical escape motility and negative phototaxis. The 16S rRNA genes of micromanipulation-purified spherical MMPs were cloned and sequenced. Phylogenetic analysis revealed that the MMP species was affiliated with Deltaproteobacteria and displayed >2.8% sequence divergence with respect to previously reported MMPs. This is the first phylogenetic identification of a spherical MMP that produces both magnetite and greigite magnetosomes. PMID:25086260

  5. Comparison of thirty-seven strains of Vd-3 bacteria with Agrobacterium radiobacter: morphological and physiological observations.

    PubMed Central

    Riley, P S; Weaver, R E

    1977-01-01

    Thirty-seven cultures of Vd-3 bacteria, isolated from clinical specimens, were characterized morphologically and physiologically. The cultures produced positive reactions when tested for oxidase, urease, nitrate reduction, phenylalanine deaminase, oxidative metabolism of carbohydrate substrates, and 3-ketolactose production. These peritrichously flagellated microorganisms were isolated primarily from the respiratory tract. When compared to authentic strains of Agrobacterium, they appeared to be most similar to A. radiobacter. Gas-liquid chromatography of trimethylsilyl derivatives of whole-cell hydrolysates of some of the Vd-3 strains and A. radiobacter yielded nearly identical elution patterns. The Vd-3 cultures were identified as probable strains of A. radiobacter. A method is presented for differentiating cultures of A. radiobacter from other similar bacteria encountered in clinical specimens. Although these bacteria rarely occur in clinical specimens, the clinical microbiologist should be familiar withe their outstanding characteristics. Images PMID:845244

  6. High-Level Genetic Diversity but No Population Structure Inferred from Nuclear and Mitochondrial Markers of the Peritrichous Ciliate Carchesium polypinum in the Grand River Basin (North America)▿ †

    PubMed Central

    Gentekaki, E.; Lynn, D. H.

    2009-01-01

    Studies that assess intraspecific genetic variation in ciliates are few and quite recent. Consequently, knowledge of the subject and understanding of the processes that underlie it are limited. We sought to assess the degree of intraspecific genetic variation in Carchesium polypinum (Ciliophora: Peritrichia), a cosmopolitan, freshwater ciliate. We isolated colonies of C. polypinum from locations in the Grand River basin in Southwestern Ontario, Canada. We then used the nuclear markers—ITS1, ITS2, and the hypervariable regions of the large subunit rRNA—and an 819-bp fragment of the mitochondrial cytochrome c oxidase I gene (cox-1) to investigate the intraspecific genetic variation of C. polypinum and the degree of resolution of the above-mentioned markers at the population level. We also sought to determine whether the organism demonstrated any population structure that mapped onto the geography of the region. Our study shows that there is a high degree of genetic diversity at the isolate level, revealed by the mitochondrial markers but not the nuclear markers. Furthermore, our results indicate that C. polypinum is likely not a single morphospecies as previously thought. PMID:19304815

  7. Artificial flagellates: Analysis of advancing motions of biflagellate micro-objects

    NASA Astrophysics Data System (ADS)

    Mori, Nobuhito; Kuribayashi, Kaori; Takeuchi, Shoji

    2010-02-01

    This paper describes an analysis of advancing motions of micro-objects with two flagella separated from a unicellular alga, Chlamydomonas reinhardtii. We harnessed their flagella as actuators of the micro-objects. The isolated flagella can be attached to microbeads and propel them. We found that the biflagellate beads tend to advance, while the uniflagellate microbeads only rotate. Our model for the motion of the biflagellate beads led to conditions for generating an advancing motion. This approach is important since it provides general guidelines for designing micro-objects driven by flagellalike actuators.

  8. The Immune Response of Hemocytes of the Insect Oncopeltus fasciatus against the Flagellate Phytomonas serpens

    PubMed Central

    Alves e Silva, Thiago L.; Vasconcellos, Luiz R. C.

    2013-01-01

    The genus Phytomonas includes parasites that are etiological agents of important plant diseases, especially in Central and South America. These parasites are transmitted to plants via the bite of an infected phytophagous hemipteran. Despite the economic impact of these parasites, many basic questions regarding the genus Phytomonas remain unanswered, such as the mechanism by which the parasites cope with the immune response of the insect vector. In this report, using a model of systemic infection, we describe the function of Oncopeltus fasciatus hemocytes in the immune response towards the tomato parasite Phytomonas serpens. Hemocytes respond to infection by trapping parasites in nodular structures and phagocytizing the parasites. In electron microscopy of hemocytes, parasites were located inside vacuoles, which appear fused with lysosomes. The parasites reached the O. fasciatus salivary glands at least six hours post-infection. After 72 hours post-infection, many parasites were attached to the salivary gland outer surface. Thus, the cellular responses did not kill all the parasites. PMID:24015207

  9. The immune response of hemocytes of the insect Oncopeltus fasciatus against the flagellate Phytomonas serpens.

    PubMed

    Alves e Silva, Thiago L; Vasconcellos, Luiz R C; Lopes, Angela H; Souto-Padrón, Thaïs

    2013-01-01

    The genus Phytomonas includes parasites that are etiological agents of important plant diseases, especially in Central and South America. These parasites are transmitted to plants via the bite of an infected phytophagous hemipteran. Despite the economic impact of these parasites, many basic questions regarding the genus Phytomonas remain unanswered, such as the mechanism by which the parasites cope with the immune response of the insect vector. In this report, using a model of systemic infection, we describe the function of Oncopeltus fasciatus hemocytes in the immune response towards the tomato parasite Phytomonas serpens. Hemocytes respond to infection by trapping parasites in nodular structures and phagocytizing the parasites. In electron microscopy of hemocytes, parasites were located inside vacuoles, which appear fused with lysosomes. The parasites reached the O. fasciatus salivary glands at least six hours post-infection. After 72 hours post-infection, many parasites were attached to the salivary gland outer surface. Thus, the cellular responses did not kill all the parasites. PMID:24015207

  10. Swimming patterns of a polarly flagellated bacterium in environments of increasing complexity

    NASA Astrophysics Data System (ADS)

    Raatz, M.; Hintsche, M.; Bahrs, M.; Theves, M.; Beta, C.

    2015-07-01

    The natural habitat of many bacterial swimmers is dominated by interfaces and narrow interstitial spacings where they frequently interact with the fluid boundaries in their vicinity. To quantify these interactions, we investigated the swimming behavior of the soil bacterium Pseudomonas putida in a variety of confined environments. Using microfluidic techniques, we fabricated structured microchannels with different configurations of cylindrical obstacles. In these environments, we analyzed the swimming trajectories for different obstacle densities and arrangements. Although the overall swimming pattern remained similar to movement in the bulk fluid, we observed a change in the turning angle distribution that could be attributed to collisions with the cylindrical obstacles. Furthermore, a comparison of the mean run length of the bacteria to the mean free path of a billiard particle in the same geometry indicated that, inside a densely packed environment, the trajectories of the bacterial swimmers are efficiently guided along the open spacings.

  11. Preliminary identification schemes for some unicellular ciliated and flagellated parasites of warmwater fishes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are few keys for the identification of small unicellular parasites of warmwater fishes and few experts who can confidently identify these parasites to species. Molecular identification tools for these parasites are largely unavailable. For fishery biologists and even fish health diagnosticia...

  12. A hybrid actuated microrobot using an electromagnetic field and flagellated bacteria for tumor-targeting therapy.

    PubMed

    Li, Donghai; Choi, Hyunchul; Cho, Sunghoon; Jeong, Semi; Jin, Zhen; Lee, Cheong; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2015-08-01

    In this paper, we propose a new concept for a hybrid actuated microrobot for tumor-targeting therapy. For drug delivery in tumor therapy, various electromagnetic actuated microrobot systems have been studied. In addition, bacteria-based microrobot (so-called bacteriobot), which use tumor targeting and the therapeutic function of the bacteria, has also been proposed for solid tumor therapy. Compared with bacteriobot, electromagnetic actuated microrobot has larger driving force and locomotive controllability due to their position recognition and magnetic field control. However, because electromagnetic actuated microrobot does not have self-tumor targeting, they need to be controlled by an external magnetic field. In contrast, the bacteriobot uses tumor targeting and the bacteria's own motility, and can exhibit self-targeting performance at solid tumors. However, because the propulsion forces of the bacteria are too small, it is very difficult for bacteriobot to track a tumor in a vessel with a large bloodstream. Therefore, we propose a hybrid actuated microrobot combined with electromagnetic actuation in large blood vessels with a macro range and bacterial actuation in small vessels with a micro range. In addition, the proposed microrobot consists of biodegradable and biocompatible microbeads in which the drugs and magnetic particles can be encapsulated; the bacteria can be attached to the surface of the microbeads and propel the microrobot. We carried out macro-manipulation of the hybrid actuated microrobot along a desired path through electromagnetic field control and the micro-manipulation of the hybrid actuated microrobot toward a chemical attractant through the chemotaxis of the bacteria. For the validation of the hybrid actuation of the microrobot, we fabricated a hydrogel microfluidic channel that can generate a chemical gradient. Finally, we evaluated the motility performance of the hybrid actuated microrobot in the hydrogel microfluidic channel. We expect that the hybrid actuated microrobot will be utilized for tumor targeting and therapy in future. PMID:25944679

  13. Microwave irradiation for shortening the processing time of samples of flagellated bacteria for scanning electron microscopy.

    PubMed

    Hernández-Chavarría, Francisco

    2004-01-01

    Microwave irradiation (MWI) has been applied to the development of rapid methods to process biological samples for scanning electron microscopy (SEM). In this paper we propose two simple and quick techniques for processing bacteria (Proteus mirabilis and Vibrio mimicus) for SEM using MWI. In the simplest methodology, the bacteria were placed on a cover-glass, air-dried, and submitted to conductivity stain. The reagent used for the conductivity stain was the mordant of a light microscopy staining method (10 ml of 5% carbolic acid solution, 2 g of tannic acid, and 10 ml of saturated aluminum sulfate 12-H2O). In the second method the samples were double fixed (glutaraldehyde and then osmium), submitted to conductivity stain, dehydrated through a series of ethanol solutions of increasing concentration, treated with hexamethyldisilazine (HMDS), and dried at 35 degrees C for 5 minutes. In both methods the steps from fixation to treatment with HMDS were done under MWI for 2 minutes in an ice-water bath, in order to dissipate the heat generated by the MWI. Although both techniques preserve bacterial morphology adequately, the latter, technique showed the best preservation, including the appearance of flagella, and that process was completed in less than 2 hours at temperatures of MWI between 4 to 5 degrees C. PMID:17061527

  14. Hydrodynamic analysis of flagellated bacteria swimming near one and between two no-slip plane boundaries

    NASA Astrophysics Data System (ADS)

    Shum, Henry; Gaffney, Eamonn A.

    2015-03-01

    The motility of swimming bacteria near solid surfaces has implications in a wide range of scenarios, including water treatment facilities, microfluidics, and biomedical implants. Using the boundary element method to numerically solve the equations of low Reynolds number fluid flow, we investigate the dynamics of a model swimmer propelled by rotating a single helical flagellum. Building on previous simulation results for swimmers near a single plane boundary, we introduce a second, parallel boundary and show that the bacterial trajectories change as the two plates are brought closer together. Analysis of this dynamical system shows that the configuration in the center of the channel and parallel to the walls is an unstable equilibrium state for large plate separations, but it becomes the only stable position for swimmers when the plate separation is reduced to three to four times the cell width. Our model also predicts that transient trajectories, i.e., those not at steady states, can exhibit curvature in the opposite sense to that expected from the well-known explanation for circular bacterial paths near a single wall.

  15. Observations on the ovulating process of the red flagellated shrimp Acetes chinensis

    NASA Astrophysics Data System (ADS)

    Chen, Qiu

    1986-12-01

    Acetes chinensis always ovulate in the dark at night. Two to five hours before ovulation, the mature oocytes change from white to orange. In the meantime, meiosis of the oocytes occurs, and reaches the metaphase just prior to ovulation. If ovarian colour change starts in the dark at night but ovulation does not start by break of dawn, ovulation will be inhibited and meiosis of the cells will be blocked.

  16. Exploring the environmental diversity of kinetoplastid flagellates in the high-throughput DNA sequencing era

    PubMed Central

    d’Avila-Levy, Claudia Masini; Boucinha, Carolina; Kostygov, Alexei; Santos, Helena Lúcia Carneiro; Morelli, Karina Alessandra; Grybchuk-Ieremenko, Anastasiia; Duval, Linda; Votýpka, Jan; Yurchenko, Vyacheslav; Grellier, Philippe; Lukeš, Julius

    2015-01-01

    The class Kinetoplastea encompasses both free-living and parasitic species from a wide range of hosts. Several representatives of this group are responsible for severe human diseases and for economic losses in agriculture and livestock. While this group encompasses over 30 genera, most of the available information has been derived from the vertebrate pathogenic genera Leishmaniaand Trypanosoma. Recent studies of the previously neglected groups of Kinetoplastea indicated that the actual diversity is much higher than previously thought. This article discusses the known segment of kinetoplastid diversity and how gene-directed Sanger sequencing and next-generation sequencing methods can help to deepen our knowledge of these interesting protists. PMID:26602872

  17. Phylogenomics demonstrates that breviate flagellates are related to opisthokonts and apusomonads

    PubMed Central

    Brown, Matthew W.; Sharpe, Susan C.; Silberman, Jeffrey D.; Heiss, Aaron A.; Lang, B. Franz; Simpson, Alastair G. B.; Roger, Andrew J.

    2013-01-01

    Most eukaryotic lineages belong to one of a few major groups. However, several protistan lineages have not yet been robustly placed in any of these groups. Both the breviates and apusomonads are two such lineages that appear to be related to the Amoebozoa and Opisthokonta (i.e. the ‘unikonts’ or Amorphea); however, their precise phylogenetic positions remain unclear. Here, we describe a novel microaerophilic breviate, Pygsuia biforma gen. nov. sp. nov., isolated from a hypoxic estuarine sediment. Ultrastructurally, this species resembles the breviate genera Breviata and Subulatomonas but has two cell morphologies, adherent and swimming. Phylogenetic analyses of the small sub-unit rRNA gene show that Pygsuia is the sister to the other breviates. We constructed a 159-protein supermatrix, including orthologues identified in RNA-seq data from Pygsuia. Phylogenomic analyses of this dataset show that breviates, apusomonads and Opisthokonta form a strongly supported major eukaryotic grouping we name the Obazoa. Although some phylogenetic methods disagree, the balance of evidence suggests that the breviate lineage forms the deepest branch within Obazoa. We also found transcripts encoding a nearly complete integrin adhesome from Pygsuia, indicating that this protein complex involved in metazoan multicellularity may have evolved earlier in eukaryote evolution than previously thought. PMID:23986111

  18. Contribution of cell body to the thrust production of flagellate bacteria

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Powers, Thomas R.; Breuer, Kenneth S.

    2013-11-01

    We trace individual motile microorganisms using a digital 3D tracking microscope in which the microscope stage follows the motion of the target. Using this technology, we not only trace a single cell over extended duration but also obtain the cell kinematics with high spatial and temporal resolution. We apply this tracking microscope to a study of Caulobacter crescentus, a bacterium that moves up to 100 microns (or 50 body lengths) per second and reverses its direction of motion by switching the rotation direction of its single helical flagellum. We show that when the cell reverses the rotation direction of the right-handed flagellum, e.g., switching from CW (a pusher) to CCW (a puller), its cell-kinematics is not completely reversible. In case of a puller, the cell almost spins along its long axis. However, in case of a pusher, besides spinning, the cell body precesses along its swimming direction, following a helical trajectory. These two types of cell-kinematics contribute to different cell motilities: the pusher rotates slower for the same swimming speed. We present a resistive force theory to account for this behavior, and by computing the torque on the cell body, we show that the finite precession angle of the bacterial pusher is optimized for swimming with fixed torque.

  19. Hydrodynamic analysis of flagellated bacteria swimming in corners of rectangular channels

    NASA Astrophysics Data System (ADS)

    Shum, Henry; Gaffney, Eamonn A.

    2015-12-01

    The influence of nearby solid surfaces on the motility of bacteria is of fundamental importance as these interactions govern the ability of the microorganisms to explore their environment and form sessile colonies. Reducing biofouling in medical implants and controlling the transport of bacterial cells in a microfluidic device are two applications that could benefit from a detailed understanding of swimming in microchannels. In this study, we investigate the self-propelled motion of a model bacterium, driven by rotating a single helical flagellum, in such an environment. In particular, we focus on the corner region of a large channel modeled as two perpendicular sections of no-slip planes joined with a rounded corner. We numerically solve the equations of Stokes flow using the boundary element method to obtain the swimming velocities at different positions and orientations relative to the channel corner. From these velocities, we construct many trajectories to ascertain the general behavior of the swimmers. Considering only hydrodynamic interactions between the bacterium and the channel walls, we show that some swimmers can become trapped near the corner while moving, on average, along the axis of the channel. This result suggests that such bacteria may be found at much higher densities in corners than in other parts of the channel. Another implication is that these corner accumulating bacteria may travel quickly through channels since they are guided directly along the corner and do not turn back or swim transversely across the channel.

  20. A small portion of plastid transcripts is polyadenylated in the flagellate Euglena gracilis.

    PubMed

    Záhonová, Kristína; Hadariová, Lucia; Vacula, Rostislav; Yurchenko, Vyacheslav; Eliáš, Marek; Krajčovič, Juraj; Vesteg, Matej

    2014-03-01

    Euglena gracilis possesses secondary plastids of green algal origin. In this study, E. gracilis expressed sequence tags (ESTs) derived from polyA-selected mRNA were searched and several ESTs corresponding to plastid genes were found. PCR experiments failed to detect SL sequence at the 5'-end of any of these transcripts, suggesting plastid origin of these polyadenylated molecules. Quantitative PCR experiments confirmed that polyadenylation of transcripts occurs in the Euglena plastids. Such transcripts have been previously observed in primary plastids of plants and algae as low-abundance intermediates of transcript degradation. Our results suggest that a similar mechanism exists in secondary plastids. PMID:24492004

  1. Does it make sense to target one tumor cell chemotactic factor or its receptor when several chemotactic axes are involved in metastasis of the same cancer?

    PubMed

    Ratajczak, Mariusz Z; Suszynska, Malwina; Kucia, Magda

    2016-12-01

    The major problem with cancer progression and anti-cancer therapy is the inherent ability of cancer cells to migrate and establish distant metastases. This ability to metastasize correlates with the presence in a growing tumor of cells with a more malignant phenotype, which express certain cancer stem cell markers. The propensity of malignant cells to migrate and their resistance to radio-chemotherapy somewhat mimics the properties of normal developmentally early stem cells that migrate during organogenesis in the developing embryo. In the past, several factors, including cell migration-promoting cytokines, chemokines, growth factors, bioactive lipids, extracellular nucleotides, and even H(+) ions, were found to influence the metastasis of cancer cells. This plethora of pro-migratory factors demonstrates the existence of significant redundancy in the chemoattractants for cancer cells. In spite of this obvious fact, significant research effort has been dedicated to demonstrating the crucial involvement of particular pro-metastatic factor-receptor axes and the development of new drugs targeting one receptor or one chemoattractant. Based on our own experience working with a model of metastatic rhabdomyosarcoma as well as the work of others, in this review we conclude that targeting a single receptor-ligand pro-metastatic axis will not effectively prevent metastasis and that we should seek other more effective therapeutic options. PMID:27510263

  2. Characterization and Reactivity of Broiler Chicken Sera to Selected Recombinant Campylobacter jejuni Chemotactic Proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Campylobacter jejuni, a Gram-negative rod bacterium, is the leading causative agent of human acute bacterial gastroenteritis worldwide. Consumption and handling of raw or undercooked poultry are regarded as a major source for human infection. Because bacterial chemotaxis guides microorganisms to c...

  3. Myosin-II sets the optimal response time scale of chemotactic amoeba

    NASA Astrophysics Data System (ADS)

    Hsu, Hsin-Fang; Westendorf, Christian; Tarantola, Marco; Bodenschatz, Eberhard; Beta, Carsten

    2014-03-01

    The response dynamics of the actin cytoskeleton to external chemical stimuli plays a fundamental role in numerous cellular functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin-II. Here we investigate the role of myosin-II in the response of the actin system to external stimuli. We used a microfluidic device in combination with a photoactivatable chemoattractant to apply stimuli to individual cells with high temporal resolution. We directly compare the actin dynamics in Dictyostelium discodelium wild type (WT) cells to a knockout mutant that is deficient in myosin-II (MNL). Similar to the WT a small population of MNL cells showed self-sustained oscillations even in absence of external stimuli. The actin response of MNL cells to a short pulse of chemoattractant resembles WT during the first 15 sec but is significantly delayed afterward. The amplitude of the dominant peak in the power spectrum from the response time series of MNL cells to periodic stimuli with varying period showed a clear resonance peak at a forcing period of 36 sec, which is significantly delayed as compared to the resonance at 20 sec found for the WT. This shift indicates an important role of myosin-II in setting the response time scale of motile amoeba. Institute of Physics und Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany.

  4. Self-Guided Supramolecular Cargo-Loaded Nanomotors with Chemotactic Behavior towards Cells.

    PubMed

    Peng, Fei; Tu, Yingfeng; van Hest, Jan C M; Wilson, Daniela A

    2015-09-28

    Delivery vehicles that are able to actively seek and precisely locate targeted tissues using concentration gradients of signaling molecules have hardly been explored. The directed movement toward specific cell types of cargo-loaded polymeric nanomotors along a hydrogen peroxide concentration gradient (chemotaxis) is reported. Through self-assembly, bowl-shaped poly(ethylene glycol)-b-polystyrene nanomotors, or stomatocytes, were formed with platinum nanoparticles entrapped in the cavity while a model drug was encapsulated in the inner compartment. Directional movement of the stomatocytes in the presence of a fuel gradient (chemotaxis) was first demonstrated in both static and dynamic systems using glass channels and a microfluidic flow. The highly efficient response of these motors was subsequently shown by their directional and autonomous movement towards hydrogen peroxide secreting neutrophil cells. PMID:26277327

  5. Inducing chemotactic and haptotactic cues in microfluidic devices for three-dimensional in vitro assays

    PubMed Central

    Moreno-Arotzena, O.; Mendoza, G.; Cóndor, M.; Rüberg, T.

    2014-01-01

    Microfluidic devices allow for the production of physiologically relevant cellular microenvironments by including biomimetic hydrogels and generating controlled chemical gradients. During transport, the biomolecules interact in distinct ways with the fibrillar networks: as purely diffusive factors in the soluble fluid or bound to the matrix proteins. These two main mechanisms may regulate distinct cell responses in order to guide their directional migration: caused by the substrate-bound chemoattractant gradient (haptotaxis) or by the gradient established within the soluble fluid (chemotaxis). In this work 3D diffusion experiments, in combination with ELISA assays, are performed using microfluidic platforms in order to quantify the distribution of PDGF-BB and TGF-β1 across collagen and fibrin gels. Furthermore, to gain a deeper understanding of the fundamental processes, the experiments are reproduced by computer simulations based on a reaction-diffusion transport model. This model yields an accurate prediction of the experimental results, confirming that diffusion and binding phenomena are established within the microdevice. PMID:25587374

  6. Decreased polymorphonuclear leucocyte chemotactic response to leukotriene B4 in cystic fibrosis.

    PubMed Central

    Lawrence, R H; Sorrelli, T C

    1992-01-01

    Evidence that leukotriene B4 (LTB4) is a significant inflammatory mediator in chronic pseudomonal respiratory disease was sought in adolescents and young adults with cystic fibrosis. Specific chemotaxis of peripheral blood polymorphonuclear leucocytes (PMN) was used as an indirect measure of remote in vivo exposure to LTB4. PMN from 17 patients showed a significant decrease in chemotaxis to 10(-7)-10(-9) M LTB4, but normal responses to 10(-8) M n-formyl-methionyl-leucyl-phenylalanine and 4 mg/ml casein, when compared with 17 healthy age- and sex-matched controls. This result is consistent with chronic production of LTB4, and specific deactivation of circulating PMN receptors for LTB4 in patients with cystic fibrosis. Pharmacologic inhibition of LTB4 production in vivo may help elucidate its role in the pathogenesis of lung damage in cystic fibrosis. PMID:1322257

  7. Butyrate regulates the expression of inflammatory and chemotactic cytokines in human acute leukemic cells during apoptosis.

    PubMed

    Pulliam, Stephanie R; Pellom, Samuel T; Shanker, Anil; Adunyah, Samuel E

    2016-08-01

    Butyrate is a histone deacetylase inhibitor implicated in many studies as a potential therapy for various forms of cancer. High concentrations of butyrate (>1.5mM) have been shown to activate apoptosis in several cancer cell lines including prostate, breast, and leukemia. Butyrate is also known to influence multiple signaling pathways that are mediators of cytokine production. The purpose of this study was to evaluate the impact of high concentrations of butyrate on the cancer microenvironment vis-à-vis apoptosis, cellular migration, and capacity to modulate cytokine expression in cancer cells. The results indicate that high concentrations of butyrate induced a 2-fold activation of caspase-3 and reduced cell viability by 60% in U937 leukemia cells. Within 24h, butyrate significantly decreased the levels of chemokines CCL2 and CCL5 in HL-60 and U937 cells, and decreased CCL5 in THP-1 leukemia cells. Differential effects were observed in treatments with valproic acid for CCL2 and CCL5 indicating butyrate-specificity. Many of the biological effects examined in this study are linked to activation of the AKT and MAPK signaling pathways; therefore, we investigated whether butyrate alters the levels of phosphorylated forms of these signaling proteins and how it correlated with the expression of chemokines. The results show that butyrate may partially regulate CCL5 production via p38 MAPK. The decrease in p-ERK1/2 and p-AKT levels correlated with the decrease in CCL2 production. These data suggest that while promoting apoptosis, butyrate has the potential to influence the cancer microenvironment by inducing differential expression of cytokines. PMID:27253488

  8. Significantly Better Than Expected Sensitivity in Chemotactic Response by a Model Unicellular Eukaryote

    NASA Astrophysics Data System (ADS)

    Franck, Carl; Segota, Igor

    2014-03-01

    Recently we demonstrated (Segota et al., J.R. Soc. Interface v. 10, 20130606 (2013)) that the conventional wisdom of what determines the signal to noise ratio in chemotaxis for the unicellular eukaryote, Dictyostelium discoideum is apparently fundamentally flawed. In our poster we will review the evidence and point to appropriate next steps in both experiment and theory.

  9. The development of concentration gradients in a suspension of chemotactic bacteria

    NASA Technical Reports Server (NTRS)

    Hillesdon, A. J.; Pedley, T. J.; Kessler, J. O.

    1995-01-01

    When a suspension of bacterial cells of the species Bacillus subtilis is placed in a chamber with its upper surface open to the atmosphere complex bioconvection patterns are observed. These arise because the cells: (1) are denser than water; and (2) usually swim upwards, so that the density of an initially uniform suspension becomes greater at the top than the bottom. When the vertical density gradient becomes large enough, an overturning instability occurs which ultimately evolves into the observed patterns. The reason that the cells swim upwards is that they are aerotactic, i.e., they swim up gradients of oxygen, and they consume oxygen. These properties are incorporated in conservation equations for the cell (N) and oxygen (C) concentrations, and these are solved in the pre-instability phase of development when N and C depend only on the vertical coordinate and time. Numerical results are obtained for both shallow- and deep-layer chambers, which are intrinsically different and require different mathematical and numerical treatments. It is found that, for both shallow and deep chambers, a thin boundary layer, densely packed with cells, forms near the surface. Beneath this layer the suspension becomes severely depleted of cells. Furthermore, in the deep chamber cases, a discontinuity in the cell concentration arises between this cell-depleted region and a cell-rich region further below, where no significant oxygen concentration gradients develop before the oxygen is fully consumed. The results obtained from the model are in good qualitative agreement with the experimental observations.

  10. Integration of the Second Messenger c-di-GMP into the Chemotactic Signaling Pathway

    PubMed Central

    Russell, Matthew H.; Bible, Amber N.; Fang, Xin; Gooding, Jessica R.; Campagna, Shawn R.; Gomelsky, Mark; Alexandre, Gladys

    2013-01-01

    ABSTRACT Elevated intracellular levels of the bacterial second messenger c-di-GMP are known to suppress motility and promote sessility. Bacterial chemotaxis guides motile cells in gradients of attractants and repellents over broad concentration ranges, thus allowing bacteria to quickly adapt to changes in their surroundings. Here, we describe a chemotaxis receptor that enhances, as opposed to suppresses, motility in response to temporary increases in intracellular c-di-GMP. Azospirillum brasilense’s preferred metabolism is adapted to microaerophily, and these motile cells quickly navigate to zones of low oxygen concentration by aerotaxis. We observed that changes in oxygen concentration result in rapid changes in intracellular c-di-GMP levels. The aerotaxis and chemotaxis receptor, Tlp1, binds c-di-GMP via its C-terminal PilZ domain and promotes persistent motility by increasing swimming velocity and decreasing swimming reversal frequency, which helps A. brasilense reach low-oxygen zones. If c-di-GMP levels remain high for extended periods, A. brasilense forms nonmotile clumps or biofilms on abiotic surfaces. These results suggest that association of increased c-di-GMP levels with sessility is correct on a long-term scale, while in the short-term c-di-GMP may actually promote, as opposed to suppress, motility. Our data suggest that sensing c-di-GMP by Tlp1 functions similar to methylation-based adaptation. Numerous chemotaxis receptors contain C-terminal PilZ domains or other sensory domains, suggesting that intracellular c-di-GMP as well as additional stimuli can be used to modulate adaptation of bacterial chemotaxis receptors. PMID:23512960

  11. Adrenergic regulation of monocyte chemotactic protein 1 leads to enhanced macrophage recruitment and ovarian carcinoma growth

    PubMed Central

    Armaiz-Pena, Guillermo N.; Gonzalez-Villasana, Vianey; Nagaraja, Archana S.; Rodriguez-Aguayo, Cristian; Sadaoui, Nouara C.; Stone, Rebecca L.; Matsuo, Koji; Dalton, Heather J.; Previs, Rebecca A.; Jennings, Nicholas B.; Dorniak, Piotr; Hansen, Jean M.; Arevalo, Jesusa M.G.; Cole, Steve W.; Lutgendorf, Susan K.; Sood, Anil K.; Lopez-Berestein, Gabriel

    2015-01-01

    Increased adrenergic signaling facilitates tumor progression, but the underlying mechanisms remain poorly understood. We examined factors responsible for stress-mediated effects on monocyte/macrophage recruitment into the tumor microenvironment, and the resultant effects on tumor growth. In vitro, MCP1 was significantly increased after catecholamine exposure, which was mediated by cAMP and PKA. Tumor samples from mice subjected to daily restraint stress had elevated MCP1 gene and protein levels, increased CD14+ cells, and increased infiltration of CD68+ cells. hMCP1 siRNA-DOPC nanoparticles significantly abrogated daily restraint stress-induced tumor growth and inhibited infiltration of CD68+ and F4/80+ cells. In ovarian cancer patients, elevated peripheral blood monocytes and tumoral macrophages were associated with worse overall survival. Collectively, we demonstrate that increased adrenergic signaling is associated with macrophage infiltration and mediated by tumor cell-derived MCP1 production. PMID:25738355

  12. A hybrid computational model to predict chemotactic guidance of growth cones

    PubMed Central

    Roccasalvo, Iolanda Morana; Micera, Silvestro; Sergi, Pier Nicola

    2015-01-01

    The overall strategy used by growing axons to find their correct paths during the nervous system development is not yet completely understood. Indeed, some emergent and counterintuitive phenomena were recently described during axon pathfinding in presence of chemical gradients. Here, a novel computational model is presented together with its ability to reproduce both regular and counterintuitive axonal behaviours. In this model, the key role of intracellular calcium was phenomenologically modelled through a non standard Gierer-Meinhardt system, as a crucial factor influencing the growth cone behaviour both in regular and complex conditions. This model was able to explicitly reproduce neuritic paths accounting for the complex interplay between extracellular and intracellular environments, through the sensing capability of the growth cone. The reliability of this approach was proven by using quantitative metrics, numerically supporting the similarity between in silico and biological results in regular conditions (control and attraction). Finally, the model was able to qualitatively predict emergent and counterintuitive phenomena resulting from complex boundary conditions. PMID:26086936

  13. Null mutations of the Dictyostelium cyclic nucleotide phosphodiesterase gene block chemotactic cell movement in developing aggregates.

    PubMed

    Sucgang, R; Weijer, C J; Siegert, F; Franke, J; Kessin, R H

    1997-12-01

    Extracellular cAMP is a critical messenger in the multicellular development of the cellular slime mold Dictyostelium discoideum. The levels of cAMP are controlled by a cyclic nucleotide phosphodiesterase (PDE) that is secreted by the cells. The PDE gene (pdsA) is controlled by three promoters that permit expression during vegetative growth, during aggregation, and in prestalk cells of the older structures. Targeted disruption of the gene aborts development, and complementation with a modified pdsA restores development. Two distinct promoters must be used for full complementation, and an inhibitory domain of the PDE must be removed. We took advantage of newly isolated PDE-null cells and the natural chimerism of the organism to ask whether the absence of PDE affected individual cell behavior. PDE-null cells aggregated with isogenic wild-type cells in chimeric mixtures, but could not move in a coordinated manner in mounds. The wild-type cells move inward toward the center of the mound, leaving many of the PDE-null cells at the periphery of the aggregate. During the later stages of development, PDE-null cells in the chimera segregate to regions which correspond to the prestalk region and the rear of the slug. Participation in the prespore/spore population returns with the restoration of a modified pdsA to the null cells. PMID:9405107

  14. Disrupting Microtubules Network Immobilizes Amoeboid Chemotactic Receptor in the Plasma Membrane

    PubMed Central

    de Keijzer, S.; Galloway, J.; Harms, G.S.; Devreotes, P.N.; Iglesias, P.A.

    2011-01-01

    Signaling cascades are initiated in the plasma membrane via activation of one molecule by another. The interaction depends on the mutual availability of the molecules to each other and this is determined by their localization and lateral diffusion in the cell membrane. The cytoskeleton plays a very important role in this process by enhancing or restricting the possibility of the signaling partners to meet in the plasma membrane. In this study we explored the mode of diffusion of the cAMP receptor, cAR1, in the plasma membrane of Dictyostelium discoideum cells and how this is regulated by the cytoskeleton. Single-particle tracking of fluorescently labeled cAR1 using total internal reflection microscopy showed that 70% of the cAR1 molecules were mobile. These receptors showed directed motion and we demonstrate that this is not because of tracking along the actin cytoskeleton. Instead, destabilization of the microtubules abolished cAR1 mobility in the plasma membrane and this was confirmed by fluorescence recovery after photobleaching. As a result of microtubule stabilization, one of the first downstream signaling events, the jump of the PH domain of CRAC, was decreased. These results suggest a role for microtubules in cAR1 dynamics and in the ability of cAR1 molecules to interact with their signaling partners. PMID:21334306

  15. Modeling the self-organized phosphatidylinositol lipid signaling system in chemotactic cells using quantitative image analysis.

    PubMed

    Shibata, Tatsuo; Nishikawa, Masatoshi; Matsuoka, Satomi; Ueda, Masahiro

    2012-11-01

    A key signaling event that is responsible for gradient sensing in eukaryotic cell chemotaxis is a phosphatidylinositol (PtdIns) lipid reaction system. The self-organization activity of this PtdIns lipid system induces an inherent polarity, even in the absence of an external chemoattractant gradient, by producing a localized PtdIns (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)]-enriched domain on the membrane. Experimentally, we found that such a domain could exhibit two types of behavior: (1) it could be persistent and travel on the membrane, or (2) be stochastic and transient. Taking advantage of the simultaneous visualization of PtdIns(3,4,5)P(3) and the enzyme phosphatase and tensin homolog (PTEN), for which PtdIns(3,4,5)P(3) is a substrate, we statistically demonstrated the inter-dependence of their spatiotemporal dynamics. On the basis of this statistical analysis, we developed a theoretical model for the self-organization of PtdIns lipid signaling that can accurately reproduce both persistent and transient domain formation; these types of formations can be explained by the oscillatory and excitability properties of the system, respectively. PMID:22899720

  16. Self-Guided Supramolecular Cargo-Loaded Nanomotors with Chemotactic Behavior towards Cells

    PubMed Central

    Peng, Fei; Tu, Yingfeng; van Hest, Jan C M; Wilson, Daniela A

    2015-01-01

    Delivery vehicles that are able to actively seek and precisely locate targeted tissues using concentration gradients of signaling molecules have hardly been explored. The directed movement toward specific cell types of cargo-loaded polymeric nanomotors along a hydrogen peroxide concentration gradient (chemotaxis) is reported. Through self-assembly, bowl-shaped poly(ethylene glycol)-b-polystyrene nanomotors, or stomatocytes, were formed with platinum nanoparticles entrapped in the cavity while a model drug was encapsulated in the inner compartment. Directional movement of the stomatocytes in the presence of a fuel gradient (chemotaxis) was first demonstrated in both static and dynamic systems using glass channels and a microfluidic flow. The highly efficient response of these motors was subsequently shown by their directional and autonomous movement towards hydrogen peroxide secreting neutrophil cells. PMID:26277327

  17. An Assay to Quantify Chemotactic Properties of Degradation Products from Extracellular Matrix

    PubMed Central

    Sicari, Brian M.; Zhang, Li; Londono, Ricardo; Badylak, Stephen F.

    2015-01-01

    The endogenous chemotaxis of cells toward sites of tissue injury and/or biomaterial implantation is an important component of the host response. Implanted biomaterials capable of recruiting host stem/progenitor cells to a site of interest may obviate challenges associated with cell transplantation. An assay for the identification and quantification of chemotaxis induced by surgically placed biologic scaffolds composed of extracellular matrix is described herein. PMID:24155230

  18. The effect of vacuum pump oil on the chemotactic behavior of soil bacteria

    SciTech Connect

    Dunifon, R.E.; Hazen, T.C.

    1990-01-01

    The use of biodegradation in the cleanup and transformation of waste materials is an economical and environmentally safe practice. Using chemotaxis, or the movement of bacteria toward or away from compounds, in biodegradation is an area that is being studied at the Savannah River Laboratory. This study investigates the inhibition of vacuum pump oil on the chemotaxis of soil bacteria. It was found that vacuum pump oil does have an inhibitory effect on the movement of bacteria. This inhibition will have to be considered when studying the possibility of using chemotaxis to degrade vacuum pump oil, or any other petroleum products. 5 refs., 5 figs.

  19. C/EBP epsilon directs granulocytic versus monocytic lineage determination and confers chemotactic function via Hlx

    PubMed Central

    Halene, Stephanie; Gaines, Peter; Sun, Hong; Zibello, Theresa; Lin, Sharon; Khanna-Gupta, Arati; Williams, Simon C.; Perkins, Archibald; Krause, Diane; Berliner, Nancy

    2010-01-01

    Objective Mutations in the C/EBPε gene have been identified in the cells of patients with neutrophil specific granule deficiency (SGD), a rare congenital disorder marked by recurrent bacterial infections. Their neutrophils, in addition to lacking specific granules required for normal respiratory burst activity, also lack normal phagocytosis and chemotaxis. Although the SGD phenotype has been replicated in C/EBPε−/− (KO) mice, the mechanisms by which C/EBPε mutations act to decrease neutrophil function are not entirely clear. Methods In order to determine the role of C/EBPε in neutrophil differentiation and migration, we generated immortalized progenitor cell lines from C/EBPε KO and wild type (WT) mice and performed expression and flow cytometric analysis and functional studies. Results Expression of lineage specific cell surface antigens on our in vitro differentiated cell lines revealed persistent expression of monocytic markers on KO granulocytes. We verified this in primary murine peripheral blood and bone marrow cells. In addition, KO BM had an increase in immature myeloid precursors at the common myeloid progenitor (CMP) and granulocyte monocyte progenitor (GMP) level suggesting a critical role for C/EBPε not only in granulocyte maturation beyond the promyelocyte stage, but also in the monocyte/granulocyte lineage decision. We found that restoration of Hlx (H2.0-like homeo box 1) expression, which was decreased in C/EBPε KO cells, rescued chemotaxis, but not the other defects of C/EBPε KO neutrophils. Summary We show two new regulatory functions of C/EBPε in myelopoiesis: in the absence of C/EBPε, there is not only incomplete differentiation of granulocytes, but myelopoiesis is disrupted with the appearance of an intermediate cell type with monocyte and granulocyte features, and the neutrophils have abnormal chemotaxis. Restoration of expression of Hlx provides partial recovery of function; it has no effect on neutrophil maturation, but can completely ameliorate the chemotaxis defect in C/EBPe KO cells. PMID:19925846

  20. A hybrid computational model to predict chemotactic guidance of growth cones

    NASA Astrophysics Data System (ADS)

    Roccasalvo, Iolanda Morana; Micera, Silvestro; Sergi, Pier Nicola

    2015-06-01

    The overall strategy used by growing axons to find their correct paths during the nervous system development is not yet completely understood. Indeed, some emergent and counterintuitive phenomena were recently described during axon pathfinding in presence of chemical gradients. Here, a novel computational model is presented together with its ability to reproduce both regular and counterintuitive axonal behaviours. In this model, the key role of intracellular calcium was phenomenologically modelled through a non standard Gierer-Meinhardt system, as a crucial factor influencing the growth cone behaviour both in regular and complex conditions. This model was able to explicitly reproduce neuritic paths accounting for the complex interplay between extracellular and intracellular environments, through the sensing capability of the growth cone. The reliability of this approach was proven by using quantitative metrics, numerically supporting the similarity between in silico and biological results in regular conditions (control and attraction). Finally, the model was able to qualitatively predict emergent and counterintuitive phenomena resulting from complex boundary conditions.

  1. Chemotactic activity of channel catfish, Ictalurus punctatus (Rafinesque), recombinant Cyclophilin A

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyclophilin A (CyPA), a member of the highly conserved immunophilin superfamily, is important to physiological and pathological processes, including immune cell signaling. Recently, several teleost fish CyPA have been cloned and characterized. However, CyPA function in fish immunity has not been f...

  2. Adrenergic regulation of monocyte chemotactic protein 1 leads to enhanced macrophage recruitment and ovarian carcinoma growth.

    PubMed

    Armaiz-Pena, Guillermo N; Gonzalez-Villasana, Vianey; Nagaraja, Archana S; Rodriguez-Aguayo, Cristian; Sadaoui, Nouara C; Stone, Rebecca L; Matsuo, Koji; Dalton, Heather J; Previs, Rebecca A; Jennings, Nicholas B; Dorniak, Piotr; Hansen, Jean M; Arevalo, Jesusa M G; Cole, Steve W; Lutgendorf, Susan K; Sood, Anil K; Lopez-Berestein, Gabriel

    2015-02-28

    Increased adrenergic signaling facilitates tumor progression, but the underlying mechanisms remain poorly understood. We examined factors responsible for stress-mediated effects on monocyte/macrophage recruitment into the tumor microenvironment, and the resultant effects on tumor growth. In vitro, MCP1 was significantly increased after catecholamine exposure, which was mediated by cAMP and PKA. Tumor samples from mice subjected to daily restraint stress had elevated MCP1 gene and protein levels, increased CD14+ cells, and increased infiltration of CD68+ cells. hMCP1 siRNA-DOPC nanoparticles significantly abrogated daily restraint stress-induced tumor growth and inhibited infiltration of CD68+ and F4/80+ cells. In ovarian cancer patients, elevated peripheral blood monocytes and tumoral macrophages were associated with worse overall survival. Collectively, we demonstrate that increased adrenergic signaling is associated with macrophage infiltration and mediated by tumor cell-derived MCP1 production. PMID:25738355

  3. Opposite and Coordinated Rotation of Amphitrichous Flagella Governs Oriented Swimming and Reversals in a Magnetotactic Spirillum

    PubMed Central

    Hérisse, Marion; Espinosa, Leon; Bossa, Alicia; Alberto, François; Wu, Long-Fei

    2015-01-01

    ABSTRACT Current knowledge regarding the mechanism that governs flagellar motor rotation in response to environmental stimuli stems mainly from the study of monotrichous and peritrichous bacteria. Little is known about how two polar flagella, one at each cell pole of the so-called amphitrichous bacterium, are coordinated to steer the swimming. Here we fluorescently labeled the flagella of Magnetospirillum magneticum AMB-1 cells and took advantage of the magnetically controllable swimming of this bacterium to investigate flagellar rotation in moving cells. We identified three motility behaviors (runs, tumbles, and reversals) and two characteristic fluorescence patterns likely corresponding to flagella rotating in opposite directions. Each AMB-1 locomotion mode was systematically associated with particular flagellar patterns at the poles which led us to conclude that, while cell runs are allowed by the asymmetrical rotation of flagellar motors, their symmetrical rotation triggers cell tumbling. Our observations point toward a precise coordination of the two flagellar motors which can be temporarily unsynchronized during tumbling. IMPORTANCE Motility is essential for bacteria to search for optimal niches and survive. Many bacteria use one or several flagella to explore their environment. The mechanism by which bipolarly flagellated cells coordinate flagellar rotation is poorly understood. We took advantage of the genetic amenability and magnetically controlled swimming of the spirillum-shaped magnetotactic bacterium Magnetospirillum magneticum AMB-1 to correlate cell motion with flagellar rotation. We found that asymmetric rotation of the flagella (counterclockwise at the lagging pole and clockwise at the leading pole) enables cell runs whereas symmetric rotation triggers cell tumbling. Taking into consideration similar observations in spirochetes, bacteria possessing bipolar ribbons of periplasmic flagella, we propose a conserved motility paradigm for spirillum

  4. Stochastic and Deterministic Flagellar Dynamics Provide a Mechanism for Eukaryotic Swimming Reorientation

    NASA Astrophysics Data System (ADS)

    Polin, Marco; Tuval, Idan; Drescher, Knut; Goldstein, Raymond

    2009-03-01

    The biflagellated alga Chlamydomonas reinhardtii is a good model organism to study the origin of flagellar synchronization. Here we employ high-speed imaging to study the beating of the two flagella of Chlamydomonas, and show that a single cell can alternate between two distinct dynamical regimes: asynchronous and synchronous. The asynchronous state is characterized by a large interflagellar frequency difference. In the synchronous state, the flagella beat in phase for lengthy periods, interrupted episodically by an extra beat of either flagellum. The statistics of these events are consistent with a model of hydrodynamically coupled noisy oscillators. Previous observations have suggested that the two flagella have well separated intrinsic beat frequencies, and are synchronized by their mutual coupling. Our analysis shows instead that the synchronized state is incompatible with coupling-induced synchronization of flagella with those intrinsic frequencies. This suggests that the beat frequencies themselves are under the control of the cell. Moreover, high-resolution three-dimensional tracking of swimming cells provides strong evidence that these dynamical states are related to non-phototactic reorientation events in the trajectories, yielding a eukaryotic equivalent of the ``run and tumble'' motion of peritrichously flagellated bacteria.

  5. Evaluation of Zosteric Acid for Mitigating Biofilm Formation of Pseudomonas putida Isolated from a Membrane Bioreactor System

    PubMed Central

    Polo, Andrea; Foladori, Paola; Ponti, Benedetta; Bettinetti, Roberta; Gambino, Michela; Villa, Federica; Cappitelli, Francesca

    2014-01-01

    This study provides data to define an efficient biocide-free strategy based on zosteric acid to counteract biofilm formation on the membranes of submerged bioreactor system plants. 16S rRNA gene phylogenetic analysis showed that gammaproteobacteria was the prevalent taxa on fouled membranes of an Italian wastewater plant. Pseudomonas was the prevalent genus among the cultivable membrane-fouler bacteria and Pseudomonas putida was selected as the target microorganism to test the efficacy of the antifoulant. Zosteric acid was not a source of carbon and energy for P. putida cells and, at 200 mg/L, it caused a reduction of bacterial coverage by 80%. Biofilm experiments confirmed the compound caused a significant decrease in biomass (−97%) and thickness (−50%), and it induced a migration activity of the peritrichous flagellated P. putida over the polycarbonate surface not amenable to a biofilm phenotype. The low octanol-water partitioning coefficient and the high water solubility suggested a low bioaccumulation potential and the water compartment as its main environmental recipient and capacitor. Preliminary ecotoxicological tests did not highlight direct toxicity effects toward Daphnia magna. For green algae Pseudokirchneriella subcapitata an effect was observed at concentrations above 100 mg/L with a significant growth of protozoa that may be connected to a concurrent algal growth inhibition. PMID:24879523

  6. Paenibacillus xanthinilyticus sp. nov., isolated from agricultural soil.

    PubMed

    Kim, Dong-uk; Kim, Song-Gun; Lee, Hyosun; Chun, Jongsik; Cho, Jang-Cheon; Ka, Jong-Ok

    2015-09-01

    A bacterial strain designated 11N27(T) was isolated from an agricultural soil sample. Cells of this strain were Gram-reaction-variable, facultatively anaerobic, endospore-forming, white-pigmented, peritrichously flagellated and hydrolysed xanthine. The major fatty acids of strain 11N27(T) were anteiso-C15 : 0, iso-C16 : 0 and C16 : 0. The polar lipid profile contained phosphatidylethanolamine, two unknown phospholipids, two unknown aminolipids, one unknown aminophospholipid and two unknown polar lipids. The G+C content of the genomic DNA of strain 11N27(T) was 50.3 mol%. MK-7 was the predominant respiratory quinone. meso-Diaminopimelic acid was the diagnostic diamino acid in the peptidoglycan. 16S rRNA gene sequence analysis showed that strain 11N27(T) was phylogenetically related to Paenibacillus mendelii C/2(T) (96.2% sequence similarity) and Paenibacillus sepulcri CMM 7311(T) (96.0%). The genotypic and phenotypic data showed that strain 11N27(T) could be distinguished from phylogenetically related species and that this strain represents a novel species of the genus Paenibacillus. The name Paenibacillus xanthinilyticus sp. nov. is proposed with the type strain 11N27(T)( = KACC 17935(T) = NBRC 109108(T)). PMID:26023205

  7. Asaia bogorensis gen. nov., sp. nov., an unusual acetic acid bacterium in the alpha-Proteobacteria.

    PubMed

    Yamada, Y; Katsura, K; Kawasaki, H; Widyastuti, Y; Saono, S; Seki, T; Uchimura, T; Komagata, K

    2000-03-01

    Eight Gram-negative, aerobic, rod-shaped and peritrichously flagellated strains were isolated from flowers of the orchid tree (Bauhinia purpurea) and of plumbago (Plumbago auriculata), and from fermented glutinous rice, all collected in Indonesia. The enrichment culture approach for acetic acid bacteria was employed, involving use of sorbitol medium at pH 3.5. All isolates grew well at pH 3.0 and 30 degrees C. They did not oxidize ethanol to acetic acid except for one strain that oxidized ethanol weakly, and 0.35% acetic acid inhibited their growth completely. However, they oxidized acetate and lactate to carbon dioxide and water. The isolates grew well on mannitol agar and on glutamate agar, and assimilated ammonium sulfate for growth on vitamin-free glucose medium. The isolates produced acid from D-glucose, D-fructose, L-sorbose, dulcitol and glycerol. The quinone system was Q-10. DNA base composition ranged from 59.3 to 61.0 mol% G + C. Studies of DNA relatedness showed that the isolates constitute a single species. Phylogenetic analysis based on their 16S rRNA gene sequences indicated that the isolates are located in the acetic acid bacteria lineage, but distant from the genera Acetobacter, Gluconobacter, Acidomonas and Gluconacetobacter. On the basis of the above characteristics, the name Asaia bogorensis gen. nov., sp. nov. is proposed for these isolates. The type strain is isolate 71T (= NRIC 0311T = JCM 10569T). PMID:10758893

  8. Pigmented nanoflagellates grazing on Synechococcus: seasonal variations and effect of flagellate size in the coastal ecosystem of subtropical Western Pacific.

    PubMed

    Chan, Ya-Fan; Tsai, An-Yi; Chiang, Kuo-Ping; Hsieh, Chih-Hao

    2009-10-01

    We investigated seasonal variation of grazing impact of the pigmented nanoflagellates (PNF) with different sizes upon Synechococcus in the subtropical western Pacific coastal waters using grazing experiments with fluorescently labeled Synechococcus (FLS). For total PNF, conspicuous seasonal variations of ingestion rates on Synechococcus were found, and a functional response was observed. To further investigate the impact of different size groups, we separated the PNF into four categories (<3, 3-5, 5-10, and >10 microm). Our results indicated that the smallest PNF (<3 microm PNF) did not ingest FLS and was considered autotrophic. PNF of 3-5 microm in size made up most of the PNF community; however, their ingestion on Synechococcus was too low (0.1-1.9 Syn PNF(-1) h(-1)) to support their growth, and they had to depend on other prey or photosynthesis to survive. The ingestion rate of the 3-5 microm group exhibited no significant seasonal variation; by contrast, the ingestion rates of 5-10 and >10 microm PNFs showed significant seasonal variation. During the warm season, 3-5 microm PNF were responsible for the grazing of 12% of Synechococcus production, 5-10 microm PNF for 48%, and >10 microm PNF for 2%. Taken together, our results demonstrate that the PNF of 3-10 microm consumed most Synechococcus during the warm season and exhibited a significant functional response to the increase in prey concentration. PMID:19655080

  9. Experimental transmission of the parasitic flagellates Trypanosoma cruzi and Trypanosoma rangeli between triatomine bugs or mice and captive neotropical bats.

    PubMed

    Thomas, Maurice E; Rasweiler Iv, John J; D'Alessandro, Antonio

    2007-08-01

    Trypanosoma cruzi and Trypanosoma rangeli-like trypanosomes have been found in a variety of neotropical bat species. In this study, bats (Artibeus lituratus, Carollia perspicillata, Desmodus rotundus, Glossophaga soricina, Molossus molossus, Phyllostomus hastatus) were maintained under controlled conditions, and experiments were conducted to determine how they might become infected naturally with trypanosomes. All bats were first screened for existing infections by hemoculture and the examination of blood smears, and only apparently uninfected animals were then used in the experiments. Proof was obtained that the triatomine bug Rhodnius prolixus would readily feed upon some of the bats, and two species became infected after being bitten by bugs infected with T. rangeli. Some bats also became infected by ingesting R. prolixus carrying T. cruzi, or following subcutaneous or intragastic inoculation with fecal suspensions of R. prolixus containing T. cruzi. P. hastatus became infected after ingesting mice carrying T. cruzi. All of the bats studied inhabit roosts that may be occupied by triatomine bugs and, with the exception of D. rotundus, all also feed to at least some extent upon insects. These findings provide further evidence of how bats may play significant roles in the epidemiology of T. cruzi and T. rangeli in the New World tropics. PMID:17710299

  10. Changes in bacterial community composition and dynamics and viral mortality rates associated with enhanced flagellate grazing in a mesoeutrophic reservoir.

    PubMed

    Simek, K; Pernthaler, J; Weinbauer, M G; Hornák, K; Dolan, J R; Nedoma, J; Masín, M; Amann, R

    2001-06-01

    Bacterioplankton from a meso-eutrophic dam reservoir was size fractionated to reduce (<0.8-microm treatment) or enhance (<5-microm treatment) protistan grazing and then incubated in situ for 96 h in dialysis bags. Time course samples were taken from the bags and the reservoir to estimate bacterial abundance, mean cell volume, production, protistan grazing, viral abundance, and frequency of visibly infected cells. Shifts in bacterial community composition (BCC) were examined by denaturing gradient gel electrophoresis (DGGE), cloning and sequencing of 16S rDNA genes from the different treatments, and fluorescence in situ hybridization (FISH) with previously employed and newly designed oligonucleotide probes. Changes in bacterioplankton characteristics were clearly linked to changes in mortality rates. In the reservoir, where bacterial production about equaled protist grazing and viral mortality, community characteristics were nearly invariant. In the "grazer-free" (0.8-microm-filtered) treatment, subject only to a relatively low mortality rate (approximately 17% day(-1)) from viral lysis, bacteria increased markedly in concentration. While the mean bacterial cell volume was invariant, DGGE indicated a shift in BCC and FISH revealed an increase in the proportion of one lineage within the beta proteobacteria. In the grazing-enhanced treatment (5-microm filtrate), grazing mortality was approximately 200% and viral lysis resulted in mortality of 30% of daily production. Cell concentrations declined, and grazing-resistant flocs and filaments eventually dominated the biomass, together accounting for >80% of the total bacteria by the end of the experiment. Once again, BCC changed strongly and a significant fraction of the large filaments was detected using a FISH probe targeted to members of the Flectobacillus lineage. Shifts of BCC were also reflected in DGGE patterns and in the increases in the relative importance of both beta proteobacteria and members of the Cytophaga-Flavobacterium cluster, which consistently formed different parts of the bacterial flocs. Viral concentrations and frequencies of infected cells were highly significantly correlated with grazing rates, suggesting that protistan grazing may stimulate viral activity. PMID:11375187

  11. Morphology, ultrastructure, and small subunit rDNA phylogeny of the marine heterotrophic flagellate Goniomonas aff. amphinema.

    PubMed

    Martin-Cereceda, Mercedes; Roberts, Emily C; Wootton, Emma C; Bonaccorso, Elisa; Dyal, Patricia; Guinea, Almudena; Rogers, Dale; Wright, Chris J; Novarino, Gianfranco

    2010-01-01

    Marine goniomonads have a worldwide distribution but ultrastructural information has not been available so far. An isolate of the heterotrophic marine nanoflagellate Goniomonas (G. aff. amphinema) from North Wales (UK) has been studied, providing information on its morphology and cellular structure using video, electron, laser scanning confocal microscopy (LSCM), and atomic force microscopy. Here, we describe a new feature, a granular area, potentially involved in particle capture and feeding. The binding of the lectin wheat germ agglutinin to the granular area of cells with discharged ejectisomes indicates the adhesive nature of this novel feature. The presence of a microtubular intracellular cytopharynx, apparently also used for feeding, has been revealed by LSCM. The small subunit rRNA gene of the isolate has been sequenced (1,788 bp). Phylogenetic results corroborate significant genetic divergence within the marine members of Goniomonas. This work highlights the need for integrated morphological, ultrastructural, and molecular investigation when describing and studying heterotrophic nanoflagellates. PMID:20015186

  12. Photosynthesis and photosynthetic pigments in the flagellate Euglena gracilis - as sensitive endpoints for toxicity evaluation of liquid detergents.

    PubMed

    Azizullah, Azizullah; Richter, Peter; Häder, Donat-Peter

    2014-04-01

    The present study was designed to validate the applicability of photosynthetic performance using a PAM fluorometer and photosynthetic pigments in Euglena gracilis as endpoint parameters in toxicity assessment of liquid detergents using a dish washing liquid detergent during short- (0-72h) and long-term (7days) exposure. In short-term experiments, the detergent affected the photosynthetic efficiency with EC50 values (calculated for Fv/Fm) of 22.07%, 7.27%, 1.4% and 2.34%, after 0, 1, 24 and 72h, respectively. The relative electron transport rate (rETR) and quantum yield measured with increasing irradiances were also inhibited by the detergent. The most severe effect of the detergent on the light-harvesting pigments (μgmL(-1)) was observed after 72h where chlorophyll a and total carotenoids were decreased at concentrations above 0.1% and chlorophyll b was decreased at concentrations above 0.5%. In long-term experiments, the detergent reduced the photosynthetic efficiency of cultures giving an EC50 value of 0.867% for Fv/Fm. rETR and quantum yield with increasing irradiance were shown to be adversely affected at concentrations of 0.1% or above. A decrease in chlorophyll a and total carotenoids (μgmL(-1)) was observed at concentrations of 0.05% detergent or above. Chlorophyll b was shown to be comparatively less affected by detergent stress, and a significant decrease was observed at concentrations of 0.5% or above. However, there was no prominent decrease in per cell (Euglena) concentration of any pigment. It can be concluded that photosynthesis and light-harvesting pigments in E. gracilis were sensitive to detergent stress and can be used as sensitive parameters in toxicity assessment of detergents in aquatic environments. PMID:24658006

  13. Cardiac Stem Cell Secretome Protects Cardiomyocytes from Hypoxic Injury Partly via Monocyte Chemotactic Protein-1-Dependent Mechanism.

    PubMed

    Park, Chi-Yeon; Choi, Seung-Cheol; Kim, Jong-Ho; Choi, Ji-Hyun; Joo, Hyung Joon; Hong, Soon Jun; Lim, Do-Sun

    2016-01-01

    Cardiac stem cells (CSCs) were known to secrete diverse paracrine factors leading to functional improvement and beneficial left ventricular remodeling via activation of the endogenous pro-survival signaling pathway. However, little is known about the paracrine factors secreted by CSCs and their roles in cardiomyocyte survival during hypoxic condition mimicking the post-myocardial infarction environment. We established Sca-1+/CD31- human telomerase reverse transcriptase-immortalized CSCs (Sca-1+/CD31- CSCs(hTERT)), evaluated their stem cell properties, and paracrine potential in cardiomyocyte survival during hypoxia-induced injury. Sca-1+/CD31- CSCs(hTERT) sustained proliferation ability even after long-term culture exceeding 100 population doublings, and represented multi-differentiation potential into cardiomyogenic, endothelial, adipogenic, and osteogenic lineages. Dominant factors secreted from Sca-1+/CD31- CSCs(hTERT) were EGF, TGF-β1, IGF-1, IGF-2, MCP-1, HGF R, and IL-6. Among these, MCP-1 was the most predominant factor in Sca-1+/CD31- CSCs(hTERT) conditioned medium (CM). Sca-1+/CD31- CSCs(hTERT) CM increased survival and reduced apoptosis of HL-1 cardiomyocytes during hypoxic injury. MCP-1 silencing in Sca-1+/CD31- CSCs(hTERT) CM resulted in a significant reduction in cardiomyocyte apoptosis. We demonstrated that Sca-1+/CD31- CSCs(hTERT) exhibited long-term proliferation capacity and multi-differentiation potential. Sca-1+/CD31- CSCs(hTERT) CM protected cardiomyocytes from hypoxic injury partly via MCP-1-dependent mechanism. Thus, they are valuable sources for in vitro and in vivo studies in the cardiovascular field. PMID:27231894

  14. The Endothelin-Integrin Axis Is Involved in Macrophage-induced Breast Cancer Cell Chemotactic Interactions with Endothelial Cells*

    PubMed Central

    Chen, Chia-Chi; Chen, Li-Li; Hsu, Yu-Ting; Liu, Ko-Jiunn; Fan, Chi-Shuan; Huang, Tze-Sing

    2014-01-01

    Elevated macrophage infiltration in tumor tissues is associated with breast cancer metastasis. Cancer cell migration/invasion toward angiogenic microvasculature is a key step in metastatic spread. We therefore studied how macrophages stimulated breast cancer cell interactions with endothelial cells. Macrophages produced cytokines, such as interleukin-8 and tumor necrosis factor-α, to stimulate endothelin (ET) and ET receptor (ETR) expression in breast cancer cells and human umbilical vascular endothelial cells (HUVECs). ET-1 was induced to a greater extent from HUVECs than from breast cancer cells, resulting in a density difference that facilitated cancer cell chemotaxis toward HUVECs. Macrophages also stimulated breast cancer cell adhesion to HUVECs and transendothelial migration, which were repressed by ET-1 antibody or ETR inhibitors. The ET axis induced integrins, such as αV and β1, and their counterligands, such as intercellular adhesion molecule-2 and P-selectin, in breast cancer cells and HUVECs, and antibodies against these integrins efficiently suppressed macrophage-stimulated breast cancer cell interactions with HUVECs. ET-1 induced Ets-like kinase-1 (Elk-1), signal transducer and activator of transcription-3 (STAT-3), and nuclear factor-κB (NF-κB) phosphorylation in breast cancer cells. The use of inhibitors to prevent their phosphorylation or ectopic overexpression of dominant-negative IκBα perturbed ET-1-induced integrin αV and integrin β1 expression. The physical associations of these three transcriptional factors with the gene promoters of the two integrins were furthermore evidenced by a chromatin immunoprecipitation assay. Finally, our mouse orthotopic tumor model revealed an ET axis-mediated lung metastasis of macrophage-stimulated breast cancer cells, suggesting that the ET axis was involved in macrophage-enhanced breast cancer cell endothelial interactions. PMID:24550382

  15. Activation of TAK1 by Chemotactic and Growth Factors, and Its Impact on Human Neutrophil Signaling and Functional Responses.

    PubMed

    Sylvain-Prévost, Stéphanie; Ear, Thornin; Simard, François A; Fortin, Carl F; Dubois, Claire M; Flamand, Nicolas; McDonald, Patrick P

    2015-12-01

    The MAP3 kinase, TAK1, is known to act upstream of IKK and MAPK cascades in several cell types, and is typically activated in response to cytokines (e.g., TNF, IL-1) and TLR ligands. In this article, we report that in human neutrophils, TAK1 can also be activated by different classes of inflammatory stimuli, namely, chemoattractants and growth factors. After stimulation with such agents, TAK1 becomes rapidly and transiently activated. Blocking TAK1 kinase activity with a highly selective inhibitor (5z-7-oxozeaenol) attenuated the inducible phosphorylation of ERK occurring in response to these stimuli but had little or no effect on that of p38 MAPK or PI3K. Inhibition of TAK1 also impaired MEKK3 (but not MEKK1) activation by fMLF. Moreover, both TAK1 and the MEK/ERK module were found to influence inflammatory cytokine expression and release in fMLF- and GM-CSF-activated neutrophils, whereas the PI3K pathway influenced this response independently of TAK1. Besides cytokine production, other responses were found to be under TAK1 control in neutrophils stimulated with chemoattractants and/or GM-CSF, namely, delayed apoptosis and leukotriene biosynthesis. Our data further emphasize the central role of TAK1 in controlling signaling cascades and functional responses in primary neutrophils, making it a promising target for therapeutic intervention in view of the foremost role of neutrophils in several chronic inflammatory conditions. PMID:26491199

  16. Cardiac Stem Cell Secretome Protects Cardiomyocytes from Hypoxic Injury Partly via Monocyte Chemotactic Protein-1-Dependent Mechanism

    PubMed Central

    Park, Chi-Yeon; Choi, Seung-Cheol; Kim, Jong-Ho; Choi, Ji-Hyun; Joo, Hyung Joon; Hong, Soon Jun; Lim, Do-Sun

    2016-01-01

    Cardiac stem cells (CSCs) were known to secrete diverse paracrine factors leading to functional improvement and beneficial left ventricular remodeling via activation of the endogenous pro-survival signaling pathway. However, little is known about the paracrine factors secreted by CSCs and their roles in cardiomyocyte survival during hypoxic condition mimicking the post-myocardial infarction environment. We established Sca-1+/CD31− human telomerase reverse transcriptase-immortalized CSCs (Sca-1+/CD31− CSCshTERT), evaluated their stem cell properties, and paracrine potential in cardiomyocyte survival during hypoxia-induced injury. Sca-1+/CD31− CSCshTERT sustained proliferation ability even after long-term culture exceeding 100 population doublings, and represented multi-differentiation potential into cardiomyogenic, endothelial, adipogenic, and osteogenic lineages. Dominant factors secreted from Sca-1+/CD31− CSCshTERT were EGF, TGF-β1, IGF-1, IGF-2, MCP-1, HGF R, and IL-6. Among these, MCP-1 was the most predominant factor in Sca-1+/CD31− CSCshTERT conditioned medium (CM). Sca-1+/CD31− CSCshTERT CM increased survival and reduced apoptosis of HL-1 cardiomyocytes during hypoxic injury. MCP-1 silencing in Sca-1+/CD31− CSCshTERT CM resulted in a significant reduction in cardiomyocyte apoptosis. We demonstrated that Sca-1+/CD31− CSCshTERT exhibited long-term proliferation capacity and multi-differentiation potential. Sca-1+/CD31− CSCshTERT CM protected cardiomyocytes from hypoxic injury partly via MCP-1-dependent mechanism. Thus, they are valuable sources for in vitro and in vivo studies in the cardiovascular field. PMID:27231894

  17. Expression of high mobility group box 1 in inflamed dental pulp and its chemotactic effect on dental pulp cells

    SciTech Connect

    Zhang, Xufang; Jiang, Hongwei; Gong, Qimei; Fan, Chen; Huang, Yihua; Ling, Junqi

    2014-08-08

    Highlights: • HMGB1 translocated from nucleus to cytoplasm during dental pulp inflammation. • HMGB1and its receptor RAGE were up-regulated in hDPCs under LPS stimulation. • HMGB1 enhanced hDPCs migration and induces cytoskeleton reorganization. • HMGB1 may play a critical role in dental pulp repair during inflamed state. - Abstract: High mobility group box 1 protein (HMGB1) is a chromatin protein which can be released extracellularly, eliciting a pro-inflammatory response and promoting tissue repair process. This study aimed to examine the expression and distribution of HMGB1 and its receptor RAGE in inflamed dental pulp tissues, and to assess its effects on proliferation, migration and cytoskeleton of cultured human dental pulp cells (DPCs). Our data demonstrated that cytoplasmic expression of HMGB1 was observed in inflamed pulp tissues, while HMGB1 expression was confined in the nuclei in healthy dental pulp. The mRNA expression of HMGB1 and RAGE were significantly increased in inflamed pulps. In in vitro cultured DPCs, expression of HMGB1 in both protein and mRNA level was up-regulated after treated with lipopolysaccharide (LPS). Exogenous HMGB1 enhanced DPCs migration in a dose-dependent manner and induced the reorganization of f-actin in DPCs. Our results suggests that HMGB1 are not only involved in the process of dental pulp inflammation, but also play an important role in the recruitment of dental pulp stem cells, promoting pulp repair and regeneration.

  18. Microfluidic study of the chemotactic response of Escherichia coli to amino acids, signaling molecules and secondary metabolites.

    PubMed

    Nagy, Krisztina; Sipos, Orsolya; Valkai, Sándor; Gombai, Éva; Hodula, Orsolya; Kerényi, Ádám; Ormos, Pál; Galajda, Péter

    2015-07-01

    Quorum sensing and chemotaxis both affect bacterial behavior on the population level. Chemotaxis shapes the spatial distribution of cells, while quorum sensing realizes a cell-density dependent gene regulation. An interesting question is if these mechanisms interact on some level: Does quorum sensing, a density dependent process, affect cell density itself via chemotaxis? Since quorum sensing often spans across species, such a feedback mechanism may also exist between multiple species. We constructed a microfluidic platform to study these questions. A flow-free, stable linear chemical gradient is formed in our device within a few minutes that makes it suitable for sensitive testing of chemoeffectors: we showed that the amino acid lysine is a weak chemoattractant for Escherichia coli, while arginine is neutral. We studied the effect of quorum sensing signal molecules of Pseudomonas aeruginosa on E. coli chemotaxis. Our results show that N-(3-oxododecanoyl)-homoserine lactone (oxo-C12-HSL) and N-(butryl)-homoserine lactone (C4-HSL) are attractants. Furthermore, we tested the chemoeffector potential of pyocyanin and pyoverdine, secondary metabolites under a quorum sensing control. Pyocyanin is proved to be a weak attractant while pyoverdine are repellent. We demonstrated the usability of the device in co-culturing experiments, where we showed that various factors released by P. aeruginosa affect the dynamic spatial rearrangement of a neighboring E. coli population, while surface adhesion of the cells is also modulated. PMID:26339306

  19. Development of a culture independent method to characterize the chemotactic response of Flavobacterium columnare to fish mucus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flavobacterium columnare, the causative agent of columnaris disease, is a significant pathogen of many freshwater fish species worldwide and is considered one of the most important pathogens impacting the channel catfish (Ictalurus punctatus Rafinesque) industry in the United States. Recent researc...

  20. CHEMOTACTIC ROLE OF NEUROTROPIN 3 IN THE EMBRYONIC TESTIS THAT FACILITATES MORPHOLOGICAL MALE SEX DETERMINATION. (R827405)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  1. Expression of high mobility group box 1 in inflamed dental pulp and its chemotactic effect on dental pulp cells.

    PubMed

    Zhang, Xufang; Jiang, Hongwei; Gong, Qimei; Fan, Chen; Huang, Yihua; Ling, Junqi

    2014-08-01

    High mobility group box 1 protein (HMGB1) is a chromatin protein which can be released extracellularly, eliciting a pro-inflammatory response and promoting tissue repair process. This study aimed to examine the expression and distribution of HMGB1 and its receptor RAGE in inflamed dental pulp tissues, and to assess its effects on proliferation, migration and cytoskeleton of cultured human dental pulp cells (DPCs). Our data demonstrated that cytoplasmic expression of HMGB1 was observed in inflamed pulp tissues, while HMGB1 expression was confined in the nuclei in healthy dental pulp. The mRNA expression of HMGB1 and RAGE were significantly increased in inflamed pulps. In in vitro cultured DPCs, expression of HMGB1 in both protein and mRNA level was up-regulated after treated with lipopolysaccharide (LPS). Exogenous HMGB1 enhanced DPCs migration in a dose-dependent manner and induced the reorganization of f-actin in DPCs. Our results suggests that HMGB1 are not only involved in the process of dental pulp inflammation, but also play an important role in the recruitment of dental pulp stem cells, promoting pulp repair and regeneration. PMID:25019990

  2. Synthetic Cystic Fibrosis Sputum Medium Regulates Flagellar Biosynthesis through the flhF Gene in Burkholderia cenocepacia

    PubMed Central

    Kumar, Brijesh; Cardona, Silvia T.

    2016-01-01

    Burkholderia cenocepacia belongs to the Burkholderia cepacia complex (Bcc), a group of at least 18 distinct species that establish chronic infections in the lung of people with the genetic disease cystic fibrosis (CF). The sputum of CF patients is rich in amino acids and was previously shown to increase flagellar gene expression in B. cenocepacia. We examined flagellin expression and flagellar morphology of B. cenocepacia grown in synthetic cystic fibrosis sputum medium (SCFM) compared to minimal medium. We found that CF nutritional conditions induce increased motility and flagellin expression. Individual amino acids added at the same concentrations as found in SCFM also increased motility but not flagellin expression, suggesting a chemotactic effect of amino acids. Electron microscopy and flagella staining demonstrated that the increase in flagellin corresponds to a change in the number of flagella per cell. In minimal medium, the ratio of multiple: single: aflagellated cells was 2:3.5:4.5; while under SCFM conditions, the ratio was 7:2:1. We created a deletion mutant, ΔflhF, to study whether this putative GTPase regulates the flagellation pattern of B. cenocepacia K56-2 during growth in CF conditions. The ΔflhF mutant exhibited 80% aflagellated, 14% single and 6% multiple flagellated bacterial subpopulations. Moreover, the ratio of multiple to single flagella in WT and ΔflhF was 3.5 and 0.43, respectively in CF conditions. The observed differences suggest that FlhF positively regulates flagellin expression and the flagellation pattern in B. cenocepacia K56-2 during CF nutritional conditions. PMID:27379216

  3. Bacterial flagellum as a propeller and as a rudder for efficient chemotaxis

    PubMed Central

    Xie, Li; Altindal, Tuba; Chattopadhyay, Suddhashil; Wu, Xiao-Lun

    2011-01-01

    We investigate swimming and chemotactic behaviors of the polarly flagellated marine bacteria Vibrio alginolyticus in an aqueous medium. Our observations show that V. alginolyticus execute a cyclic, three-step (forward, reverse, and flick) swimming pattern that is distinctively different from the run–tumble pattern adopted by Escherichia coli. Specifically, the bacterium backtracks its forward swimming path when the motor reverses. However, upon resuming forward swimming, the flagellum flicks and a new swimming direction is selected at random. In a chemically homogeneous medium (no attractant or repellent), the consecutive forward tf and backward tb swimming times are uncorrelated. Interestingly, although tf and tb are not distributed in a Poissonian fashion, their difference Δt = |tf - tb| is. Near a point source of attractant, on the other hand, tf and tb are found to be strongly correlated, and Δt obeys a bimodal distribution. These observations indicate that V. alginolyticus exploit the time-reversal symmetry of forward and backward swimming by using the time difference to regulate their chemotactic behavior. By adopting the three-step cycle, cells of V. alginolyticus are able to quickly respond to a chemical gradient as well as to localize near a point source of attractant. PMID:21205908

  4. Noise-Induced Increase of Sensitivity in Bacterial Chemotaxis.

    PubMed

    He, Rui; Zhang, Rongjing; Yuan, Junhua

    2016-07-26

    Flagellated bacteria, like Escherichia coli, can swim toward beneficial environments by modulating the rotational direction of their flagellar motors through a chemotaxis signal transduction network. The noise of this network, the random fluctuation of the intracellular concentration of the signal protein CheY-P with time, has been identified in studies of single cell behavioral variability, and found to be important in coordination of multiple motors in a bacterium and in enhancement of bacterial drift velocity in chemical gradients. Here, by comparing the behavioral difference between motors of wild-type E. coli and mutants without signal noise, we measured the magnitude of this noise in wild-type cells, and found that the noise increases the sensitivity of the bacterial chemotaxis network downstream at the level of the flagellar motor. This provided a simple mechanism for the noise-induced enhancement of chemotactic drift, which we confirmed by simulating the E. coli chemotactic motion in various spatial profiles of chemo-attractant concentration. PMID:27463144

  5. The sensory transduction pathways in bacterial chemotaxis

    NASA Technical Reports Server (NTRS)

    Taylor, Barry L.

    1989-01-01

    Bacterial chemotaxis is a useful model for investigating in molecular detail the behavioral response of cells to changes in their environment. Peritrichously flagellated bacteria such as coli and typhimurium swim by rotating helical flagella in a counterclockwise direction. If flagellar rotation is briefly reversed, the bacteria tumble and change the direction of swimming. The bacteria continuously sample the environment and use a temporal sensing mechanism to compare the present and immediate past environments. Bacteria respond to a broad range of stimuli including changes in temperature, oxygen concentration, pH and osmotic strength. Bacteria are attracted to potential sources of nutrition such as sugars and amino acids and are repelled by other chemicals. In the methylation-dependent pathways for sensory transduction and adaptation in E. coli and S. typhimurium, chemoeffectors bind to transducing proteins that span the plasma membrane. The transducing proteins are postulated to control the rate of autophosphorylation of the CheA protein, which in turn phosphorylates the CheY protein. The phospho-CheY protein binds to the switch on the flagellar motor and is the signal for clockwise rotation of the motor. Adaptation to an attractant is achieved by increasing methylation of the transducing protein until the attractant stimulus is cancelled. Responses to oxygen and certain sugars involve methylation-independent pathways in which adaption occurs without methylation of a transducing protein. Taxis toward oxygen is mediated by the electron transport system and changes in the proton motive force. Recent studies have shown that the methylation-independent pathway converges with the methylation-dependent pathway at or before the CheA protein.

  6. Anoxybacillus kamchatkensis sp. nov., a novel thermophilic facultative aerobic bacterium with a broad pH optimum from the Geyser valley, Kamchatka.

    PubMed

    Kevbrin, Vadim V; Zengler, Karsten; Lysenko, Anatolii M; Wiegel, Juergen

    2005-10-01

    A facultative aerobic, moderately thermophilic, spore forming bacterium, strain JW/VK-KG4 was isolated from an enrichment culture obtained from the Geyser valley, a geo-thermally heated environment located in the Kamchatka peninsula (Far East region of Russia). The cells were rod shaped, motile, peritrichous flagellated stained Gram positive and had a Gram positive type cell wall. Aerobically, the strain utilized a range of carbohydrates including glucose, fructose, trehalose, proteinuous substrates, and pectin as well. Anaerobically, only carbohydrates are utilized. When growing on carbohydrates, the strain required yeast extract and vitamin B(12). Anaerobically, glucose was fermented to lactate as main product and acetate, formate, ethanol as minor products. Aerobically, even in well-aerated cultures (agitated at 500 rpm), glucose oxidation was incomplete and lactate and acetate were found in culture supernatants as by-products. Optimal growth of the isolate was observed at pH(25 C) 6.8-8.5 and 60 degrees C. The doubling times on glucose at optimal growth conditions were 34 min (aerobically) and 40 min (anaerobically). The G+C content was 42.3 mol% as determined by T(m) assay. Sequence analysis of the 16S rRNA gene indicated an affiliation of strain JW/VK-KG4 with Anoxybacillus species. Based on its morphology, physiology, phylogenetic relationship and its low DNA-DNA homology with validly published species of Anoxybacillus, it is proposed that strain JW/VK-KG4 represents a new species in the genus Anoxybacillus as A. kamchatkensis sp. nov. The type strain for the novel species is JW/VK-KG4(T) (=DSM 14988, =ATCC BAA-549). The GenBank accession number for the 16S rDNA sequence is AF510985. PMID:16142505

  7. An integrative approach to phylogeny reveals patterns of environmental distribution and novel evolutionary relationships in a major group of ciliates

    PubMed Central

    Sun, Ping; Clamp, John; Xu, Dapeng; Huang, Bangqin; Shin, Mann Kyoon

    2016-01-01

    Peritrichs are a major group of ciliates with worldwide distribution. Yet, its internal phylogeny remains unresolved owing to limited sampling. Additionally, ecological distributions of peritrichs are poorly known. We performed substantially expanded phylogenetic analyses of peritrichs that incorporated SSU rDNA sequences of samples collected from three continents, revealing a number of new relationships between and within major lineages that greatly challenged the classic view of the group. Interrogation of a dataset comprising new environmental sequences from an estuary and the open ocean generated with high throughput sequencing and clone libraries plus putative environmental peritrich sequences at Genbank, produced a comprehensive tree of peritrichs from a variety of habitats and revealed unique ecological distribution patterns of several lineages for the first time. Also, evidence of adaptation to extreme environments in the Astylozoidae clade greatly broadened the phylogenetic range of peritrichs capable of living in extreme environments. Reconstruction of ancestral states revealed that peritrichs may have transitioned repeatedly from freshwater to brackish/marine/hypersaline environments. This work establishes a phylogenetic framework for more mature investigations of peritrichs in the future, and the approach used here provides a model of how to elucidate evolution in the context of ecological niches in any lineage of microbial eukaryotes. PMID:26880590

  8. MRI-based Medical Nanorobotic Platform for the Control of Magnetic Nanoparticles and Flagellated Bacteria for Target Interventions in Human Capillaries

    PubMed Central

    Martel, Sylvain; Felfoul, Ouajdi; Mathieu, Jean-Baptiste; Chanu, Arnaud; Tamaz, Samer; Mohammadi, Mahmood; Mankiewicz, Martin; Tabatabaei, Nasr

    2009-01-01

    Medical nanorobotics exploits nanometer-scale components and phenomena with robotics to provide new medical diagnostic and interventional tools. Here, the architecture and main specifications of a novel medical interventional platform based on nanorobotics and nanomedicine, and suited to target regions inaccessible to catheterization are described. The robotic platform uses magnetic resonance imaging (MRI) for feeding back information to a controller responsible for the real-time control and navigation along pre-planned paths in the blood vessels of untethered magnetic carriers, nanorobots, and/or magnetotactic bacteria (MTB) loaded with sensory or therapeutic agents acting like a wireless robotic arm, manipulator, or other extensions necessary to perform specific remote tasks. Unlike known magnetic targeting methods, the present platform allows us to reach locations deep in the human body while enhancing targeting efficacy using real-time navigational or trajectory control. The paper describes several versions of the platform upgraded through additional software and hardware modules allowing enhanced targeting efficacy and operations in very difficult locations such as tumoral lesions only accessible through complex microvasculature networks. PMID:19890446

  9. The changes in ultrastructure during fertilization of the colourless flagellate Polytoma papillatum with special reference to the configural changes of their mitochondria.

    PubMed

    Gaffal, K P; Schneider, G J

    1978-10-01

    Changes in the morphology of the mitochondrial inventory (= chondriome), the nucleus and the flagellar apparatus during the generative (sexual) life cycle of Polytoma papillatum were examined by means of the serial sectioning technique. At the onset of copulation gametes do not differ obviously from interphase cells of the vegetative (asexual) life cycle, in that, both primarily contain one basket-shaped mitochondrion. The quadriflagellate and binucleate zygote exhibits a chondriome which consists of one large highly reticulated basket at the periphery of the zygote and 33 smaller mitochondrial units. Therefore, the basket clearly results from fusion of the two gamete chondriomes. The smaller mitochondrial fragments are either spherical to ovoid or elongated and poorly branched; they tend to occupy more central regions of the zygote. After karyogamy the mitochondrial basket disintegrates into several fragments of various shapes and sizes. Most of the mitochondrial fragments are located at the periphery. At the onset of karyogamy the nuclei and the flagellar apparatuses do not differ significantly from those of the gametes and vegetative interphase cells. The diploid nucleus, however, is characterized by: 1. many spherical bodies (diameter: ca. 200 to 600 nm) which are found both in the nucleoplasm and in the nucleolus. The major part of these bodies consists of material whose ultrastructure resembles that of the "pars fibrosa" in the nucleolus; 2. three deep invaginations of the nuclear membrane, two of which extend to the nucleolus; 3. an increase of nucleoplasm-filled cavities in the nucleolar "pars granulosa". The four flagella are considerably shortened; the basal bodies bound to the flagella have lost their striated connection and the roots have nearly completely disappeared. The results are compared with those obtained from investigations in Chlamydomonas; their significance in extranuclear genetics and in the systematics of Volvocales is discussed. PMID:568573

  10. Moramonas marocensis gen. nov., sp. nov.: a jakobid flagellate isolated from desert soil with a bacteria-like, but bloated mitochondrial genome

    PubMed Central

    Strassert, Jürgen F. H.; Tikhonenkov, Denis V.; Pombert, Jean-François; Kolisko, Martin; Tai, Vera; Mylnikov, Alexander P.; Keeling, Patrick J.

    2016-01-01

    A new jakobid genus has been isolated from Moroccan desert soil. The cyst-forming protist Moramonas marocensis gen. nov., sp. nov. has two anteriorly inserted flagella of which one points to the posterior cell pole accompanying the ventral feeding groove and is equipped with a dorsal vane—a feature typical for the Jakobida. It further shows a flagellar root system consisting of singlet microtubular root, left root (R1), right root (R2) and typical fibres associated with R1 and R2. The affiliation of M. marocensis to the Jakobida was confirmed by molecular phylogenetic analyses of the SSU rRNA gene, five nuclear genes and 66 mitochondrial protein-coding genes. The mitochondrial genome has the high number of genes typical for jakobids, and bacterial features, such as the four-subunit RNA polymerase and Shine–Dalgarno sequences upstream of the coding regions of several genes. The M. marocensis mitochondrial genome encodes a similar number of genes as other jakobids, but is unique in its very large genome size (greater than 264 kbp), which is three to four times higher than that of any other jakobid species investigated yet. This increase seems to be due to a massive expansion in non-coding DNA, creating a bloated genome like those of plant mitochondria. PMID:26887409

  11. Opposite Regulation of the Copy Number and the Expression of Plastid and Mitochondrial Genes by Light and Acetate in the Green Flagellate Chlorogonium.

    PubMed Central

    Kroymann, J.; Schneider, W.; Zetsche, K.

    1995-01-01

    In the unicellular green alga Chlorogonium elongatum (Chlamydomonadaceae), the formation of both the photosynthetic and the respiratory apparatus is under the control of light and acetate. Autotrophically cultured cells possess a 3-fold higher copy number of the plastid genes rbcL and psbA than cells cultivated in the dark with acetate (heterotrophic cells). Under mixotrophic conditions (light and acetate), both genes are present at an intermediate level. This pattern is repeated at the mRNA level. The amounts of rbcL and psbA mRNAs are approximately 3-fold higher in autotrophic cells than in heterotrophic ones and are intermediate in mixotrophic cells. As expected, the copy number of the nuclear-encoded rbcS gene is constant irrespective of the applied culture conditions. RbcS mRNA, however, is 7-fold more frequent in autotrophic than in heterotrophic cells. Again, mixotrophic cells show an intermediate level. In contrast to genes encoding plastid proteins, the copy number and transcript level of the mitochondrial cob gene are approximately 5-fold higher in heterotrophic cells than in autotrophic ones. As before, mixotrophic cells take an intermediate position. Therefore, light and acetate control the genes involved in the formation of either the photosynthetic or the respiratory apparatus in a coordinated but opposite manner. PMID:12228568

  12. Lower concentrations of chemotactic cytokines and soluble innate factors in the lower female genital tract associated with use of injectable hormonal contraceptive

    PubMed Central

    Ngcapu, Sinaye; Masson, Lindi; Sibeko, Sengeziwe; Werner, Lise; McKinnon, Lyle R.; Mlisana, Koleka; Shey, Muki; Samsunder, Natasha; Karim, Salim Abdool; Karim, Quarraisha Abdool; Passmore, Jo-Ann S.

    2016-01-01

    Progesterone-based injectable hormonal contraceptives (HCs) potentially modulate genital barrier integrity and regulate the innate immune environment in the female genital tract, thereby enhancing risk for STIs or HIV infection. We investigated the effects of injectable HC use on concentrations of inflammatory cytokines and other soluble factors associated with genital epithelial repair and integrity. The concentrations of 42 inflammatory, regulatory, adaptive, growth factors and hematopoetic cytokines, five matrix metalloproteinases (MMPs), and four tissue inhibitors of metalloproteinases (TIMPs) were measured in cervicovaginal lavages (CVLs) from 64 HIV negative women using injectable HCs and 64 control women not using any HCs, in a matched case-control study. There were no differences between groups in the prevalence of bacterial vaginosis (BV; nugent score ≥7), or common sexually transmitted infections (STIs). In multivariate analyses adjusting for condom use, sex work status, marital status, BV and STIs, median concentrations of chemokines (eotaxin, MCP-1, MDC), adaptive cytokines (IL-15), growth factors (PDGF-AA) and a metalloproteinase (TIMP-2) were significantly lower in CVLs from women using injectable HCs than controls. In addition, pro-inflammatory cytokine IL-12p40 and chemokine fractalkine were less likely to have detectable levels in women using injectable HCs compared to those not using HCs. We conclude that injectable HC use was associated with an immunosuppressive female genital tract innate immune profile. While the relationship between injectable HC use and STI or HIV risk is yet to be resolved, our data suggest that injectable HCs effects were similar between STI positive and STI negative participants. PMID:25956139

  13. Urinary chemokine (C-C motif) ligand 2 (monocyte chemotactic protein-1) as a tubular injury marker for early detection of cisplatin-induced nephrotoxicity

    PubMed Central

    Nishihara, Kumiko; Masuda, Satohiro; Shinke, Haruka; Ozawa, Aiko; Ichimura, Takaharu; Yonezawa, Atsushi; Nakagawa, Shunsaku; Inui, Ken-ichi; Bonventre, Joseph V.; Matsubara, Kazuo

    2014-01-01

    Because of the difficulty in detecting segment-specific response in the kidney, we investigated the molecular events underlying acute kidney injury in the proximal tubules of rats with cisplatin (cis-diamminedichloroplatinum II)-induced nephrotoxicity. Microarray analysis revealed that mRNA levels of several cytokines and chemokines, such as interleukin-1beta, chemokine (C-C motif) ligand (CCL) 2, CCL20, chemokine (C-X-C motif) ligand (CXCL) 1, and CXCL10 were significantly increased after cisplatin treatment in both isolated proximal tubules and whole kidney. Interestingly, tubular CCL2 mRNA levels increased soon after cisplatin administration, whereas CCL2 mRNA levels in whole kidney first decreased and then increased. Levels of both CCL2 and kidney injury molecule-1 (KIM-1) in the whole kidney increased after cisplatin administration. Immunofluorescence analysis revealed CCL2 changes in the proximal tubular cells initially and then in the medullary interstitium. Urinary CCL2 excretion significantly increased approximately 3-fold compared with controls the day after cisplatin administration (5 mg/kg), when no changes were observed plasma creatinine and blood urea nitrogen levels. Urinary levels of KIM-1 also increased 3-fold after cisplatin administration. In addition, urinary CCL2 rather than KIM-1 increased in chronic renal failure rats after administration of low-dose cisplatin (2 mg/kg), suggesting that urinary CCL2 was selective for cisplatin-induced nephrotoxicity in renal impairment. These results indicated that the increase in cytokine and chemokine expression in renal epithelial cells might be responsible for kidney deterioration in cisplatin-induced nephrotoxicity, and that urinary CCL2 is associated with tubular injury and serves as a sensitive and noninvasive marker for the early detection of cisplatin-induced tubular injury. PMID:23291264

  14. The Lupane-type Triterpene 30-Oxo-calenduladiol Is a CCR5 Antagonist with Anti-HIV-1 and Anti-chemotactic Activities*

    PubMed Central

    Barroso-González, Jonathan; El Jaber-Vazdekis, Nabil; García-Expósito, Laura; Machado, José-David; Zárate, Rafael; Ravelo, Ángel G.; Estévez-Braun, Ana; Valenzuela-Fernández, Agustín

    2009-01-01

    The existence of drug-resistant human immunodeficiency virus (HIV) viruses in patients receiving antiretroviral treatment urgently requires the characterization and development of new antiretroviral drugs designed to inhibit resistant viruses and to complement the existing antiretroviral strategies against AIDS. We assayed several natural or semi-synthetic lupane-type pentacyclic triterpenes in their ability to inhibit HIV-1 infection in permissive cells. We observed that the 30-oxo-calenduladiol triterpene, compound 1, specifically impaired R5-tropic HIV-1 envelope-mediated viral infection and cell fusion in permissive cells, without affecting X4-tropic virus. This lupane derivative competed for the binding of a specific anti-CCR5 monoclonal antibody or the natural CCL5 chemokine to the CCR5 viral coreceptor with high affinity. 30-Oxo-calenduladiol seems not to interact with the CD4 antigen, the main HIV receptor, or the CXCR4 viral coreceptor. Our results suggest that compound 1 is a specific CCR5 antagonist, because it binds to the CCR5 receptor without triggering cell signaling or receptor internalization, and inhibits RANTES (regulated on activation normal T cell expressed and secreted)-mediated CCR5 internalization, intracellular calcium mobilization, and cell chemotaxis. Furthermore, compound 1 appeared not to interact with β-chemokine receptors CCR1, CCR2b, CCR3, or CCR4. Thereby, the 30-oxo-calenduladiol-associated anti-HIV-1 activity against R5-tropic virus appears to rely on the selective occupancy of the CCR5 receptor to inhibit CCR5-mediated HIV-1 infection. Therefore, it is plausible that the chemical structure of 30-oxo-calenduladiol or other related dihydroxylated lupane-type triterpenes could represent a good model to develop more potent anti-HIV-1 molecules to inhibit viral infection by interfering with early fusion and entry steps in the HIV life cycle. PMID:19386595

  15. Molecular cloning and characterization of chemokine-like factor 1 (CKLF1), a novel human cytokine with unique structure and potential chemotactic activity.

    PubMed Central

    Han, W; Lou, Y; Tang, J; Zhang, Y; Chen, Y; Li, Y; Gu, W; Huang, J; Gui, L; Tang, Y; Li, F; Song, Q; Di, C; Wang, L; Shi, Q; Sun, R; Xia, D; Rui, M; Tang, J; Ma, D

    2001-01-01

    Cytokines are small proteins that have an essential role in the immune and inflammatory responses. The repertoire of cytokines is becoming diverse and expanding. Here we report the identification and characterization of a novel cytokine designated as chemokine-like factor 1 (CKLF1). The full-length cDNA of CKLF1 is 530 bp long and a single open reading frame encoding 99 amino acid residues. CKLF1 bears no significant similarity to any other known cytokine in its amino acid sequence. Expression of CKLF1 can be partly inhibited by interleukin 10 in PHA-stimulated U937 cells. Recombinant CKLF1 is a potent chemoattractant for neutrophils, monocytes and lymphocytes; moreover, it can stimulate the proliferation of murine skeletal muscle cells. These results suggest that CKLF1 might have important roles in inflammation and in the regeneration of skeletal muscle. PMID:11415443

  16. Mannose-Binding Lectin Inhibits the Motility of Pathogenic Salmonella by Affecting the Driving Forces of Motility and the Chemotactic Response

    PubMed Central

    Nakamura, Shuichi; Islam, Md. Shafiqul; Guo, Yijie; Ihara, Kohei; Tomioka, Rintaro; Masuda, Mizuki; Yoneyama, Hiroshi; Isogai, Emiko

    2016-01-01

    Mannose-binding lectin (MBL) is a key pattern recognition molecule in the lectin pathway of the complement system, an important component of innate immunity. MBL functions as an opsonin which enhances the sequential immune process such as phagocytosis. We here report an inhibitory effect of MBL on the motility of pathogenic bacteria, which occurs by affecting the energy source required for motility and the signaling pathway of chemotaxis. When Salmonella cells were treated with a physiological concentration of MBL, their motile fraction and free-swimming speed decreased. Rotation assays of a single flagellum showed that the flagellar rotation rate was significantly reduced by the addition of MBL. Measurements of the intracellular pH and membrane potential revealed that MBL affected a driving force for the Salmonella flagellum, the electrochemical potential difference of protons. We also found that MBL treatment increased the reversal frequency of Salmonella flagellar rotation, which interfered with the relative positive chemotaxis toward an attractive substrate. We thus propose that the motility inhibition effect of MBL may be secondarily involved in the attack against pathogens, potentially facilitating the primary role of MBL in the complement system. PMID:27104738

  17. THE EFFECTS OF COMBINATORIAL EXPOSURE OF PRO-INFLAMMATORY AND ANTI-INFLAMMATORY CYTOKINES ON AIRWAY EPITHELIAL CELL RELEASE OF CHEMOTACTIC MEDIATORS

    EPA Science Inventory

    Asthma is a chronic inflammatory disorder of the airways affecting nearly 15 million individuals nationally. Within the inflamed asthmatic airway there exist complex interactions between many cells and the cytokines they release, in particular mast cells, eosinophils, T-lymphocy...

  18. Short-Term Heat Exposure Inhibits Inflammation by Abrogating Recruitment of and Nuclear Factor-κB Activation in Neutrophils Exposed to Chemotactic Cytokines

    PubMed Central

    Choi, Mira; Salanova, Birgit; Rolle, Susanne; Wellner, Maren; Schneider, Wolfgang; Luft, Friedrich C.; Kettritz, Ralph

    2008-01-01

    Cytokines, such as granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-8 attract neutrophils into inflammatory sites. During emigration from the blood neutrophils interact with extracellular matrix proteins such as fibronectin. Fibronectin provides β2-integrin co-stimulation, allowing GM-CSF and IL-8 to activate nuclear factor (NF)-κB, an effect that does not occur in suspension. We tested the hypothesis that exposure of mice to fever-like temperatures abrogates neutrophil recruitment and NF-κB activation in a mouse model of skin inflammation. Mice that were exposed to 40°C for 1 hour showed strongly reduced GM-CSF- and IL-8-induced neutrophilic skin inflammation. In vitro heat exposure did not interfere with neutrophil adhesion or spreading on fibronectin but strongly inhibited migration toward both cytokines. Using specific inhibitors, we found that PI3-K/Akt was pivotal for neutrophil migration and that heat down-regulated this pathway. Furthermore, neutrophils on fibronectin showed abrogated NF-κB activation in response to GM-CSF and IL-8 after heat. In vivo heat exposure of mice followed by ex vivo stimulation of isolated bone marrow neutrophils confirmed these results. Finally, less NF-κB activation was seen in the inflammatory lesions of mice exposed to fever-like temperatures as demonstrated by in situ hybridization for IκBα mRNA. These new findings suggest that heat may have anti-inflammatory effects in neutrophil-dependent inflammation. PMID:18187571

  19. Zoothamnium duplicatum infestation of cultured horseshoe crabs (Limulus polyphemus).

    PubMed

    Shinn, Andrew P; Mühlhölzl, Alexander P; Coates, Christopher J; Metochis, Christoforos; Freeman, Mark A

    2015-02-01

    An outbreak of the sessile peritrich Zoothamnium duplicatum in a pilot, commercial-scale Limulus polyphemus hatchery resulted in the loss of ∼96% (40,000) second/third instar larvae over a 61day period. peritrich growth was heavy, leading to mechanical obstruction of the gills and physical damage. The peritrichs were controlled without resultant loss of juvenile crabs by administering 10ppm chlorine in freshwater for 1h and the addition of aquarium grade sand; a medium into which the crabs could burrow and facilitate cleaning of the carapace. Peritrich identity was confirmed from a partial SSU rDNA contiguous sequence of 1343bp (99.7% similarity to Z. duplicatum). PMID:25499897

  20. Flagella Structure and Gene Sequences of the Fish Pathogen Edwardsiella ictaluri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edwardsiella icatluri the cause of enteric septicemia in channel catfish (Ictalurus punctatus) are motile by means of peritrichous flagella, a virulence determinant. Molecular composition of this polymeric structure in E. ictaluri remains largely unknown. Methods: Monoclonal antibodies (MAbs) develo...

  1. Synchronization of Eukaryotic Flagella and the Evolution of Multicellularity

    NASA Astrophysics Data System (ADS)

    Goldstein, Raymond

    2009-03-01

    Flagella, among the most highly conserved structures in eukaryotes, are responsible for such tasks as fluid transport, motility and phototaxis, establishment of embryonic left-right asymmetry, and intercellular communication, and are thought to have played a key role in the development of multicellularity. These tasks are usually performed by the coordinated action of groups of flagella (from pairs to thousands), which display various types of spatio-temporal organization. The origin and quantitative characterization of flagellar synchronization has remained an important open problem, involving interplay between intracellular biochemistry and interflagellar mechanical/hydrodynamic coupling. The Volvocine green algae serve as useful model organisms for the study of these phenomena, as they form a lineage spanning from unicellular Chlamydomonas to germ-soma differentiated Volvox, having as many as 50,000 biflagellated surface somatic cells. In this talk I will describe extensive studies [1], using micromanipulation and high-speed imaging, of the flagellar synchronization of two key species - Chlamydomonas reinhardtii and Volvox carteri - over tens of thousands of cycles. With Chlamydomonas we find that the flagellar dynamics moves back and forth between a stochastic synchronized state consistent with a simple model of hydrodynamically coupled noisy oscillators, and a deterministic one driven by a large interflagellar frequency difference. These results reconcile previously contradictory studies, based on short observations, showing only one or the other of these two states, and, more importantly, show that the flagellar beat frequencies themselves are regulated by the cell. Moreover, high-resolution three-dimensional tracking of swimming cells provides strong evidence that these dynamical states are related to reorientation events in the trajectories, yielding a eukaryotic equivalent of the ``run and tumble'' motion of peritrichously flagellated bacteria. The degree

  2. Bacteria are not too small for spatial sensing of chemical gradients: An experimental evidence

    PubMed Central

    Thar, Roland; Kühl, Michael

    2003-01-01

    By analyzing the chemotactic behavior of a recently described marine bacterial species, we provide experimental evidence that bacteria are not too small for sensing chemical gradients spatially. The bipolar flagellated vibrioid bacteria (typical size 2 × 6 μm) exhibit a unique motility pattern as they translate along as well as rotate around their short axis, i.e., the pathways of the cell poles describe a double helix. The natural habitat of the bacteria is characterized by steep oxygen gradients where they accumulate in a band at their preferred oxygen concentration of ≈2 μM. Single cells leaving the band toward the oxic region typically return to the band within 16 s following a U-shaped track. A detailed analysis of the tracks reveals that the cells must be able to sense the oxygen gradient perpendicular to their swimming direction. Thus, they can detect oxygen gradients along a distance of ≈5 μm corresponding to the extension of their long axis. The observed behavior can be explained by the presence of two independent sensor regions at either cell pole that modulate the rotation speed of the polar flagellar bundles, i.e., the flagellar bundle at the cell pole exposed to higher oxygen concentration is rotating faster than the other bundle. A mathematical model based on these assumptions reproduces the observed swimming behavior of the bacteria. PMID:12719518

  3. High efficiency motility of bacteria-driven liposome with raft domain binding method.

    PubMed

    Kojima, Masaru; Zhang, Zhenhai; Nakajima, Masahiro; Fukuda, Toshio

    2012-12-01

    From the viewpoint of energy efficiency and size reduction, many people have proposed the use of microbes as actuators. Some bacteria can swim in an aqueous environment. Therefore, flagellated chemotactic bacteria have been utilized as actuators for the propulsion of micro-objects by randomly attaching several bacteria to their surface. A liposome is a well-known component used for drug delivery that can contain biologically active compounds. In the present study, we used an antibody and biotin-streptavidin binding technique to combine bacteria and liposomes and create bacteria-driven liposomes. Furthermore, a novel raft domain binding technique was developed and used to limit the attachment of bacteria to small areas of the liposome surface. The effect of the number and configuration of the attached bacteria on propulsion speed was then studied experimentally. The motility of the raft domain liposome with bacteria was higher than that of the normal liposome with bacteria. This method could be used to create bacteria-driven liposomes with highly efficient motility and could lead to the development of microrobots as drug delivery systems. PMID:23053448

  4. Restoration of flagellar clockwise rotation in bacterial envelopes by insertion of the chemotaxis protein CheY.

    PubMed Central

    Ravid, S; Matsumura, P; Eisenbach, M

    1986-01-01

    When cells of the bacterium Salmonella typhimurium are incubated with penicillin and lysed in a dilute buffer, flagellated cytoplasm-free envelopes are formed. When the envelopes are tethered to glass by their flagella and then energized, some of them spin. The direction of rotation of wild-type envelopes is exclusively counterclockwise (CCW). We perturbed this system by including in the lysis medium (and hence in the envelopes) the chemotaxis protein CheY. As a result, some of the envelopes rotated exclusively clockwise (CW). The fraction of envelopes that did so increased with the concentration of CheY; at a concentration of 48 microM (pH 8), all functional envelopes spun CW. The fraction also increased with the pH of the lysis medium in the range of 6.6-8.4. The results were the same in the presence or absence of intracellular Ca2+. Reconstituted envelopes failed to respond to chemotactic stimuli. None of them changed the direction of their rotation. However, when the intracellular pH was lowered to 6.6 or below, envelopes that spun CW stopped rotating, while envelopes that spun CCW continued to rotate. This phenomenon was reversible. We conclude that CheY per se, without any additional free cytoplasmic mediators, interacts with a switch at the base of the flagellum to cause CW rotation. PMID:3532103

  5. Quantitative investigation of bacterial chemotaxis at the single-cell level

    NASA Astrophysics Data System (ADS)

    Min, Taejin

    Living cells sense and respond to constantly changing environmental conditions. Depending on the type of stimuli, the cell may response by altering gene expression pattern, secreting molecules, or migrating to a different environment. Directed movement of cells in response to chemical stimuli is called chemotaxis. In bacterial chemotaxis, small extracellular molecules bind receptor proteins embedded in the cell membrane, which then transmit the signal inside the cell through a cascade of protein-protein interactions. This chain of events influences the behavior of motor proteins that drive the rotation of helical filaments called flagella. Individual cells of the gut-dwelling bacteria Escherichia coli (E. coli) have many such flagella, whose collective action results in the swimming behavior of the cell. A recent study found that in absence of chemical stimuli, fluctuations in the protein cascade can cause non-Poissonian switching behavior in the flagellar motor (2). A corollary was that extension of such behavior to the whole-cell swimming level would have implications for E. coli's foraging strategy. However, existence of such behavior at the swimming cell level could not be predicted a priori, since the mapping from single flagellum behavior to the swimming behavior of a multi-flagellated cell is complex and poorly understood (3, 4). Here we characterize the chemotactic behavior of swimming E. coli cells using a novel optical trap-based measurement technique. This technique allows us to trap individual cells and monitor their swimming behavior over long time periods with high temporal resolution. We find that swimming cells exhibit non-Poissonian switching statistics between different swimming states, in a manner similar to the rotational direction-switching behavior seen in individual flagella. Furthermore, we develop a data analysis routine that allows us to characterize higher order swimming features such as reversal of swimming direction and existence of

  6. Whole-Transcriptome Shotgun Sequencing (RNA-seq) Screen Reveals Upregulation of Cellobiose and Motility Operons of Lactobacillus ruminis L5 during Growth on Tetrasaccharides Derived from Barley β-Glucan

    PubMed Central

    Lawley, Blair; Sims, Ian M.

    2013-01-01

    Lactobacillus ruminis is an inhabitant of human bowels and bovine rumens. None of 10 isolates (three from bovine rumen, seven from human feces) of L. ruminis that were tested could utilize barley β-glucan for growth. Seven of the strains of L. ruminis were, however, able to utilize tetrasaccharides (3-O-β-cellotriosyl-d-glucose [LDP4] or 4-O-β-laminaribiosyl-d-cellobiose [CDP4]) present in β-glucan hydrolysates for growth. The tetrasaccharides were generated by the use of lichenase or cellulase, respectively. To learn more about the utilization of tetrasaccharides by L. ruminis, whole-transcriptome shotgun sequencing (RNA-seq) was tested as a transcriptional screen to detect altered gene expression when an autochthonous human strain (L5) was grown in medium containing CDP4. RNA-seq results were confirmed and extended by reverse transcription-quantitative PCR assays of selected genes in two upregulated operons when cells were grown as batch cultures in medium containing either CDP4 or LDP4. The cellobiose utilization operon had increased transcription, particularly in early growth phase, whereas the chemotaxis/motility operon was upregulated in late growth phase. Phenotypic changes were seen in relation to upregulation of chemotaxis/flagellar operons: flagella were rarely seen by electron microscopy on glucose-grown cells but cells cultured in tetrasaccharide medium were commonly flagellated. Chemotactic movement toward tetrasaccharides was demonstrated in capillary cultures. L. ruminis utilized 3-O-β-cellotriosyl-d-glucose released by β-glucan hydrolysis due to bowel commensal Coprococcus sp., indicating that cross feeding of tetrasaccharide between bacteria could occur. Therefore, the RNA-seq screen and subsequent experiments had utility in revealing foraging attributes of gut commensal Lactobacillus ruminis. PMID:23851085

  7. Fertilization of sea urchin eggs and sperm motility are negatively impacted under low hypergravitational forces significant to space flight

    NASA Technical Reports Server (NTRS)

    Tash, J. S.; Kim, S.; Schuber, M.; Seibt, D.; Kinsey, W. H.

    2001-01-01

    Sperm and other flagellates swim faster in microgravity (microG) than in 1 G, raising the question of whether fertilization is altered under conditions of space travel. Such alterations have implications for reproduction of plant and animal food and for long-term space habitation by man. We previously demonstrated that microG accelerates protein phosphorylation during initiation of sperm motility but delays the sperm response to the egg chemotactic factor, speract. Thus sperm are sensitive to changes in gravitational force. New experiments using the NiZeMi centrifugal microscope examined whether low hypergravity (hyperG) causes effects opposite to microG on sperm motility, signal transduction, and fertilization. Sperm % motility and straight-line velocity were significantly inhibited by as little as 1.3 G. The phosphorylation states of FP130, an axonemal phosphoprotein, and FP160, a cAMP-dependent salt-extractable flagellar protein, both coupled to motility activation, showed a more rapid decline in hyperG. Most critically, hyperG caused an approximately 50% reduction in both the rate of sperm-egg binding and fertilization. The similar extent of inhibition of both fertilization parameters in hyperG suggests that the primary effect is on sperm rather than eggs. These results not only support our earlier microG data demonstrating that sperm are sensitive to small changes in gravitational forces but more importantly now show that this sensitivity affects the ability of sperm to fertilize eggs. Thus, more detailed studies on the impact of space flight on development should include studies of sperm function and fertilization.

  8. Whole-transcriptome shotgun sequencing (RNA-seq) screen reveals upregulation of cellobiose and motility operons of Lactobacillus ruminis L5 during growth on tetrasaccharides derived from barley β-glucan.

    PubMed

    Lawley, Blair; Sims, Ian M; Tannock, Gerald W

    2013-09-01

    Lactobacillus ruminis is an inhabitant of human bowels and bovine rumens. None of 10 isolates (three from bovine rumen, seven from human feces) of L. ruminis that were tested could utilize barley β-glucan for growth. Seven of the strains of L. ruminis were, however, able to utilize tetrasaccharides (3-O-β-cellotriosyl-d-glucose [LDP4] or 4-O-β-laminaribiosyl-d-cellobiose [CDP4]) present in β-glucan hydrolysates for growth. The tetrasaccharides were generated by the use of lichenase or cellulase, respectively. To learn more about the utilization of tetrasaccharides by L. ruminis, whole-transcriptome shotgun sequencing (RNA-seq) was tested as a transcriptional screen to detect altered gene expression when an autochthonous human strain (L5) was grown in medium containing CDP4. RNA-seq results were confirmed and extended by reverse transcription-quantitative PCR assays of selected genes in two upregulated operons when cells were grown as batch cultures in medium containing either CDP4 or LDP4. The cellobiose utilization operon had increased transcription, particularly in early growth phase, whereas the chemotaxis/motility operon was upregulated in late growth phase. Phenotypic changes were seen in relation to upregulation of chemotaxis/flagellar operons: flagella were rarely seen by electron microscopy on glucose-grown cells but cells cultured in tetrasaccharide medium were commonly flagellated. Chemotactic movement toward tetrasaccharides was demonstrated in capillary cultures. L. ruminis utilized 3-O-β-cellotriosyl-d-glucose released by β-glucan hydrolysis due to bowel commensal Coprococcus sp., indicating that cross feeding of tetrasaccharide between bacteria could occur. Therefore, the RNA-seq screen and subsequent experiments had utility in revealing foraging attributes of gut commensal Lactobacillus ruminis. PMID:23851085

  9. 5T4 oncofetal antigen is expressed in high risk of relapse childhood pre-B acute lymphoblastic leukemia and is associated with a more invasive and chemotactic phenotype.

    PubMed

    Castro, F V; McGinn, O J; Krishnan, S; Marinov, G; Li, J; Rutkowski, A J; Elkord, E; Burt, D J; Holland, M; Vaghjiani, R; Gallego, A; Saha, V; Stern, P L

    2012-07-01

    Although the overall prognosis in childhood acute lymphoblastic leukemia (ALL) is good, outcome after relapse is poor. Recurrence is frequently characterized by the occurrence of disease at extramedullary sites, such as the central nervous system and testes. Subpopulations of blasts able to migrate to such areas may have a survival advantage and give rise to disease recurrence. Gene expression profiling of 85 diagnostic pre-B-ALL bone marrow samples revealed higher 5T4 oncofetal antigen transcript levels in cytogenetic high-risk subgroups of patients (P<0.001). Flow cytometric analysis determined that bone marrow from relapse patients have a significantly higher percentage of 5T4-positive leukemic blasts than healthy donors (P=0.005). The high-risk Sup-B15 pre-B-ALL line showed heterogeneity in 5T4 expression, and the derived, 5T4(+) (Sup5T4) and 5T4(-) (Sup) subline cells, displayed differential spread to the omentum and ovaries following intraperitoneal inoculation of immunocompromised mice. Consistent with this, Sup5T4 compared with Sup cells show increased invasion in vitro concordant with increased LFA-1 and VLA-4 integrin expression, adhesion to extracellular matrix and secretion of matrix metalloproteases (MMP-2/-9). We also show that 5T4-positive Sup-B15 cells are susceptible to 5T4-specific superantigen antibody-dependent cellular toxicity providing support for targeted immunotherapy in high-risk pre-B-ALL. PMID:22266911

  10. Organization and sequence of four flagellin-encoding genes of Edwardsiella icataluri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edwardsiella ictaluri, the cause of enteric septicemia in channel catfish (Ictalurus punctatus), is motile by means of peritrichous flagella. We determined the complete flagellin gene sequences and their organization in E. ictaluri by sequencing genomic segments selected from a lambda-ZAP phage gen...

  11. Complete genome sequence of channel catfish gastrointestinal sepicemia isolate Edwardsiella tarda C07-087

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edwardsiella tarda is the etiologic agent of acute to chronic edwardsiellosis in fish and other species (1). It is a gram-negative facultative anaerobe that is motile by peritrichous flagella. Edwardsiellosis is an important fish disease that negatively impacts aquaculture industries throughout the...

  12. [Research of chemotaxis response of Botrytis cinerea and Alternaria panax on total ginsenosides].

    PubMed

    Chi, Kun; Xu, Yong-hua; Lei, Feng-jie; Yin, Min-jing; Wang, Zhuang; Zhang, Ai-hua; Zhang, Lian-xue

    2015-10-01

    In this paper, three kinds of chemotactic parameters (concentration, temperature and pH) were determined by plate assay and spore germination method to research the chemotactic response of Botrytis cinerea and Alternaria panax, and their spores on total ginsenosides. The results showed that Botrytis cinerea had strong chemotactic response at the mid-concentration of total ginsenosides (cultivation temperature was 20 degrees C and pH value was 6), and the data of chemotactic migration index (CMI) was 1.293 0, chemotactic growth rate (CGR) was 0.476 0, spore germination rate (SGR) was 53%, and dry weight of mycelial (DWM) was 0.452 6 g x L(-1); however, Alternaria panax had strong chemotactic response at the low-concentration of total ginsenosides (cultivation temperature was 25 degrees C and pH value was 6), and the data of chemotactic migration index (CMI) was 1.235 4, chemotactic growth rate (CGR) was 0.537 0, spore germination rate (SGR) was 67%, and dry weight of mycelial (DWM) was 0.494 8 g x L(-1). The results indicated that the low and middle concentration (2, 20 mg x L(-1)) of total ginsenosides had significant promoting effect on chemotactic response of these two pathogens, and the spore germination, mycelial growth rate, dry weight of mycelial of them were also significantly improved by this chemotactic response, whereas it decreased as the increase of total ginsenosides concentration. PMID:26975095

  13. RECONSTRUCTING THE EARLY EVOLUTION OF FUNGI USING A SIX-GENE PHYLOGENY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to modern-day Chytridiomycete fungi (chytrids). Current classifications for the fungi assume that the chytrids form an early-diverging clade of Fungi, and imply that there was a single loss of the flagel...

  14. Chemotaxis of Aeromonas hydrophila to the surface mucus of fish

    SciTech Connect

    Hazen, T.C.; Esch, G.W.; Dimock, R.V. Jr.; Mansfield, A.

    1982-01-01

    Isolates of Aeromonas hydrophila from various sources show different chemotactic responses to mucus from the surface of freshwater fish. Some isolates were nonchemotactic to fish surface mucus. Isolates of A. hydrophila from fish lesions had a significantly higher chemotactic index than isolates of A. hydrophila from water. Maximum chemotactic responses occurred more often to diluted fish mucus than to undiluted samples. Fish which were experimentally stressed did not produce mucus that was more or less chemotactic than that of unstressed fish. Fish with red-sore lesions produced surface mucus which was not chemotactic to A. hydrophila. Differences between fish, for any isolate, were also not significant. The chemotactic substance(s) in fish mucus has a molecular weight of approximately 100,000 and did not appear to be labile when heated to 56/sup 0/C.

  15. Transport behavior of groundwater protozoa and protozoan-sized microspheres in sandy aquifer sediments

    USGS Publications Warehouse

    Harvey, R.W.; Kinner, N.E.; Bunn, A.; MacDonald, D.; Metge, D.

    1995-01-01

    Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ cell size, 2 to 3 ??m) flagellates, which are relatively abundant in the Cape Cod aquifer, were isolated from core samples, grown in a grass extract medium, labeled with hydroethidine (a vital eukaryotic stain), and coinjected into aquifer sediments along with bromide, a conservative tracer. The 2-??m flagellates appeared to be near the optimal size for transport, judging from flowthrough column experiments involving a polydispersed (0.7 to 6.2 ??m in diameter) suspension of carboxylated microspheres. However, immobilization within the aquifer sediments accounted for a log unit reduction over the first meter of travel compared with a log unit reduction over the first 10 m of travel for indigenous, free-living groundwater bacteria in earlier tests. High rates of flagellate immobilization in the presence of aquifer sediments also was observed in the laboratory. However, immobilization rates for the laboratory-grown flagellates (initially 4 to 5 ??m) injected into the aquifer were not constant and decreased noticeably with increasing time and distance of travel. The decrease in propensity for grain surfaces was accompanied by a decrease in cell size, as the flagellates presumably readapted to aquifer conditions. Retardation and apparent dispersion were generally at least twofold greater than those observed earlier for indigenous groundwater bacteria but were much closer to those observed for highly surface active carboxylated latex microspheres. Field and laboratory results suggest that 2- ??m carboxylated microspheres may be useful as analogs in investigating several abiotic

  16. Transport Behavior of Groundwater Protozoa and Protozoan-Sized Microspheres in Sandy Aquifer Sediments

    PubMed Central

    Harvey, R. W.; Kinner, N. E.; Bunn, A.; MacDonald, D.; Metge, D.

    1995-01-01

    Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ cell size, 2 to 3 (mu)m) flagellates, which are relatively abundant in the Cape Cod aquifer, were isolated from core samples, grown in a grass extract medium, labeled with hydroethidine (a vital eukaryotic stain), and coinjected into aquifer sediments along with bromide, a conservative tracer. The 2-(mu)m flagellates appeared to be near the optimal size for transport, judging from flowthrough column experiments involving a polydispersed (0.7 to 6.2 (mu)m in diameter) suspension of carboxylated microspheres. However, immobilization within the aquifer sediments accounted for a log unit reduction over the first meter of travel compared with a log unit reduction over the first 10 m of travel for indigenous, free-living groundwater bacteria in earlier tests. High rates of flagellate immobilization in the presence of aquifer sediments also was observed in the laboratory. However, immobilization rates for the laboratory-grown flagellates (initially 4 to 5 (mu)m) injected into the aquifer were not constant and decreased noticeably with increasing time and distance of travel. The decrease in propensity for grain surfaces was accompanied by a decrease in cell size, as the flagellates presumably readapted to aquifer conditions. Retardation and apparent dispersion were generally at least twofold greater than those observed earlier for indigenous groundwater bacteria but were much closer to those observed for highly surface active carboxylated latex microspheres. Field and laboratory results suggest that 2-(mu)m carboxylated microspheres may be useful as analogs in investigating several

  17. Evidence for bacterial chemotaxis to cyanobacteria from a radioassay technique. [Lyngbya birgei; Aphanizomenon flos-aquae; Aeromonas hydrophila

    SciTech Connect

    Kangatharalingam, N.; Wang, Lizhu; Priscu, J.C. )

    1991-08-01

    Lyngbya birgei and Aphanizomenon flos-aquae elicited a significant chemotactic attraction of Aeromonas hydrophila compared with controls lacking cyanobacteria. There was a positive exponential relationship between biomass (chlorophyll a) of L. birgei and A. flos-aquae and chemotactic attraction of A. hydrophila. The assay equipment was simple and reliable and could be used to study bacterial chemotaxis in other species in situ.

  18. Spatial control of actin polymerization during neutrophil chemotaxis

    PubMed Central

    Weiner, Orion D.; Servant, Guy; Welch, Matthew D.; Mitchison, Timothy J.; Sedat, John W.; Bourne, Henry R.

    2010-01-01

    Neutrophils respond to chemotactic stimuli by increasing the nucleation and polymerization of actin filaments, but the location and regulation of these processes are not well understood. Here, using a permeabilized-cell assay, we show that chemotactic stimuli cause neutrophils to organize many discrete sites of actin polymerization, the distribution of which is biased by external chemotactic gradients. Furthermore, the Arp2/3 complex, which can nucleate actin polymerization, dynamically redistributes to the region of living neutrophils that receives maximal chemotactic stimulation, and the least-extractable pool of the Arp2/3 complex co-localizes with sites of actin polymerization. Our observations indicate that chemoattractant-stimulated neutrophils may establish discrete foci of actin polymerization that are similar to those generated at the posterior surface of the intracellular bacterium Listeria monocytogenes. We propose that asymmetrical establishment and/or maintenance of sites of actin polymerization produces directional migration of neutrophils in response to chemotactic gradients. PMID:10559877

  19. SYSTEMIC HEXAMITID (PROTOZOA: DIPLOMONADIDA) INFECTION IN SEAWATER PEN-REARED CHINOOK SALMON ONCORHYNCHUS TSSHAWYTSCHA

    EPA Science Inventory

    A systemic infection with a diplomonad flagellate resembling Hexamita salmonis caused high mortality in chinook salmon, Oncorhynchus tshawytscha, reared at a seawater netpen farm in British Columbia, Canada. ffected fish were anemic and had swollen abdomens containing serosanguin...

  20. Freshwater biodiversity of Guam. 1. Introduction, with new records of ciliates and a heliozoan

    PubMed Central

    LOBBAN, CHRISTOPHER S.; SCHEFTER, MARÍA

    2008-01-01

    Inland waters are the most endangered ecosystems in the world because of complex threats and management problems, yet the freshwater microbial eukaryotes and microinvertebrates are generally not well known and from Guam are virtually unknown. Photodocumentation can provide useful information on such organisms. In this paper we document protists from mostly lentic inland waters of Guam and report twelve freshwater ciliates, especially peritrichs, which are the first records of ciliates from Guam or Micronesia. We also report a species of Raphidiophrys (Heliozoa). Undergraduate students can meaningfully contribute to knowledge of regional biodiversity through individual or class projects using photodocumentation. PMID:19079802

  1. Freshwater biodiversity of Guam. 1. Introduction, with new records of ciliates and a heliozoan.

    PubMed

    Lobban, Christopher S; Schefter, María

    2008-01-01

    Inland waters are the most endangered ecosystems in the world because of complex threats and management problems, yet the freshwater microbial eukaryotes and microinvertebrates are generally not well known and from Guam are virtually unknown. Photodocumentation can provide useful information on such organisms. In this paper we document protists from mostly lentic inland waters of Guam and report twelve freshwater ciliates, especially peritrichs, which are the first records of ciliates from Guam or Micronesia. We also report a species of Raphidiophrys (Heliozoa). Undergraduate students can meaningfully contribute to knowledge of regional biodiversity through individual or class projects using photodocumentation. PMID:19079802

  2. Characterization of Phaeocystis globosa (Prymnesiophyceae), the blooming species in the Southern North Sea

    NASA Astrophysics Data System (ADS)

    Rousseau, Véronique; Lantoine, François; Rodriguez, Francisco; LeGall, Florence; Chrétiennot-Dinet, Marie-Josèphe; Lancelot, Christiane

    2013-02-01

    Despite significant research dedicated to the marine genus Phaeocystis, which forms large blooms in the coastal waters of the Southern North Sea, some aspects of the taxonomy and biology of this species still suffer from a sketchy knowledge. It is currently admitted that P. globosa is the species that blooms in the Southern North Sea. This has however, never been confirmed by SSU rDNA sequencing which constitutes nowadays, together with the morphology of the haploid flagellate, a reliable taxonomic criterion to distinguish between Phaeocystis species. Also, although the fine morphology of the haploid scaly flagellate is well known, there is a lack of comparable and harmonized description of the other cell types, i.e. colonial cells and diploid flagellates, previously identified within the Phaeocystis life cycle. In this study, we used SSU rDNA sequencing, light and electron scanning microscopy and flow cytometry to identify and characterize three cell types produced in controlled and reproducible manner from two strains of Phaeocystis isolated from the Belgian coastal zone. Our morphometry and sequencing data confirm unambiguously that P. globosa is the species that blooms in the Southern North Sea, but suggest in addition that both strains are representative of the original P. globosa Scherffel. Our study compares, for the first time since the species description, the fine morphometry and ploidy features of diploid colonial cells, diploid and haploid flagellates originating from same strains, providing therefore unambiguous identification criteria for distinguishing them from each other. The diploid stage, colonial or flagellated cell, is thus characterized by a naked surface, has a size range nearly twice that of the haploid flagellate and do not produce the chitinous filaments specific of the haploid stage. Colonial cells lack flagella and haptonema but possess on their apical side two appendages, which elongate to form the flagella of the diploid flagellate.

  3. Zoospore chemotaxis of mangrove thraustochytrids from Hong Kong.

    PubMed

    Fan, K W; Vrijmoed, L L P; Jones, E B G

    2002-01-01

    Zoospores of mangrove isolates of Schizochytrium mangrovei KF6, KF7, KF12 (three strains), Thraustochytrium striatum KF9 and Ulkenia sp. KF13 were examined for their chemotactic responses to amino acids, carbohydrates, ethanol, and leaf extracts using a capillary root model. Most leaf extracts of mangrove plants and a marsh grass tested were shown to induce moderate chemotactic responses in zoospores of both S. mangrovei KF6 and Ulkenia sp. KF13. Of the remaining amino acids and carbohydrates evaluated, glutamic acid and pectin induced strong attraction in zoospores of S. mangrovei KF6 and Ulkenia sp. KF13, suggesting these are the major components in leaves which may be responsible for the chemotactic response of thraustochytrid zoospores in nature. Zoospores of T. striatum KF9, in general, showed a weak chemotactic response to all the tested compounds and extracts except cellulose, which elicited a moderate response. The ecological significance of the data presented is discussed. PMID:21156530

  4. DECREASED HEART RATE IS ASSOCIATED WITH CARBAMATE-INDUCED ACTIVATION OF PRO-INFLAMMATORY SERUM PROTEINS.

    EPA Science Inventory

    Previously we reported that chlorpyrifos (CHP), an irreversible cholinesterase (ChE) inhibitor, induces hypertension in rats. Concomitant with hypertension, we found an increase in C-reactive protein, macrophage inflammatory protein-2 , monocyte chemotactic protein-5 and interfer...

  5. The effects of nutrient chemotaxis on bacterial aggregation patterns with non-linear degenerate cross diffusion

    NASA Astrophysics Data System (ADS)

    Leyva, J. Francisco; Málaga, Carlos; Plaza, Ramón G.

    2013-11-01

    This paper studies a reaction-diffusion-chemotaxis model for bacterial aggregation patterns on the surface of thin agar plates. It is based on the non-linear degenerate cross diffusion model proposed by Kawasaki et al. (1997) [5] and it includes a suitable nutrient chemotactic term compatible with such type of diffusion, as suggested by Ben-Jacob et al. (2000) [20]. An asymptotic estimation predicts the growth velocity of the colony envelope as a function of both the nutrient concentration and the chemotactic sensitivity. It is shown that the growth velocity is an increasing function of the chemotactic sensitivity. High resolution numerical simulations using Graphic Processing Units (GPUs), which include noise in the diffusion coefficient for the bacteria, are presented. The numerical results verify that the chemotactic term enhances the velocity of propagation of the colony envelope. In addition, the chemotaxis seems to stabilize the formation of branches in the soft-agar, low-nutrient regime.

  6. Antimicrobial peptide scolopendrasin VII, derived from the centipede Scolopendra subspinipes mutilans, stimulates macrophage chemotaxis via formyl peptide receptor 1.

    PubMed

    Park, Yoo Jung; Lee, Ha Young; Jung, Young Su; Park, Joon Seong; Hwang, Jae Sam; Bae, Yoe-Sik

    2015-08-01

    In this study, we report that one of the antimicrobial peptides scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates actin polymerization and the subsequent chemotactic migration of macrophages through the activation of ERK and protein kinase B (Akt) activity. The scolopendrasin VII-induced chemotactic migration of macrophages is inhibited by the formyl peptide receptor 1 (FPR1) antagonist cyclosporine H. We also found that scolopendrasin VII stimulate the chemotactic migration of FPR1-transfected RBL-2H3 cells, but not that of vector-transfected cells; moreover, scolopendrasin VII directly binds to FPR1. Our findings therefore suggest that the antimicrobial peptide scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates macrophages, resulting in chemotactic migration via FPR1 signaling, and the peptide can be useful in the study of FPR1-related biological responses. PMID:26129676

  7. ARSENITE ACTIVATES KB-DEPENDENT IL-8 GENE EXPRESSION IN AIRWAY EPITHELIM IN THE ABSENCE OF NUCLEAR TRANSLOCATION OF NF-KB

    EPA Science Inventory

    Airway epithelial cells respond to certain environmental stresses by mounting a proinflammatory response, which is characterized by enhanced synthesis and release of the neutrophil chemotactic and activating factor interleukin-8 (IL-8). IL-8 expression is regulated at the transcr...

  8. Food selection by bacterivorous protists: insight from the analysis of the food vacuole content by means of fluorescence in situ hybridization.

    PubMed

    Jezbera, Jan; Hornák, Karel; Simek, Karel

    2005-05-01

    A modified fluorescence in situ hybridization (FISH) method was used to analyze bacterial prey composition in protistan food vacuoles in both laboratory and natural populations. Under laboratory conditions, we exposed two bacterial strains (affiliated with beta- and gamma-Proteobacteria -- Aeromonas hydrophila and Pseudomonas fluorescens, respectively) to grazing by three protists: the flagellates Bodo saltans and Goniomonas sp., and the ciliate Cyclidium glaucoma. Both flagellate species preferably ingested A. hydrophila over P. fluorescens, while C. glaucoma showed no clear preferences. Differences were found in the digestion of bacterial prey with B. saltans digesting significantly faster P. fluorescens compared to two other protists. The field study was conducted in a reservoir as part of a larger experiment. We monitored changes in the bacterial prey composition available compared to the bacteria ingested in flagellate food vacuoles. Bacteria detected by probe HGC69a (Actinobacteria) and R-BT065 were negatively selected by flagellates. Bacteria detected by probe CF319a were initially positively selected but along with a temporal shift in bacterial cell size, this trend changed to negative selection during the experiment. Overall, our analysis of protistan food vacuole content indicated marked effects of flagellate prey selectivity on bacterioplankton community composition. PMID:16329920

  9. [Influence of Professor Konstanty Janicki's discoveries on progress in protistology].

    PubMed

    Kazubski, Stanisław L

    2005-01-01

    Professor Konstanty Janicki published 11 protozoological papers. They concern the flagellate parasites of cockroaches and termites, as well as the amebas parasitising cockroaches and chaetognaths. He described the morphology and cytology of 12 species of flagellates, including 4 new species and genera. Three new species parasitising termites belong to the Parabasalia, one--Oxymonas granulosa, without the Golgi apparatus, initiated a new group of protista, the Oxymonadida Grassé, 1952. Konstanty Janicki also examined some important questions dealing with protozoology such as: (1) Karyomastigont. Janicki analysed the connection of the cell nucleus to the mastigont system in flagellates from termites and cockroaches. Also he described the replication of karyomastigonts of some species. This organelle plays an important part in the discussions on evolution of the lower Protista. (2) Parabasal apparatus. Janicki described the parabasal body in flagellates from cockroaches and termites, paying special attention to its peculiarities. This organelle was later named: "Janicki-type parabasal apparatus" and together with pleuromitosis became the main characters of an independent group of protista--Parabasalia. (3) Parasome. Konstanty Janicki also studied the enigmatic body (parasome, Nebenkörper), near the cell nucleus and staining like it, in amebas from the genus Paramoeba. He described this body dividing. After TEM investigation of Janickina (=Paramoeba) pigmentifera, this body is presently recognized as an endosymbiotic flagellate. Summing up, it may be stated that all findings of Professor Konstanty Janicki were the object of further investigations and occupy an important place in protistology. PMID:16913509

  10. Warming and Acidification Effects on Planktonic Heterotrophic Pico- and Nanoflagellates in a Mesocosm Experiment.

    PubMed

    Moustaka-Gouni, Maria; Kormas, Konstantinos A; Scotti, Marco; Vardaka, Elisabeth; Sommer, Ulrich

    2016-08-01

    We studied the response of the heterotrophic flagellate (HF) community to the combined impact of warming and ocean acidification in a mesocosm experiment with a plankton community from the western Baltic Sea. We performed a quantitative analysis of the response at the level of total biomass and size classes and a semi-quantitative one at the level of individual taxa. Total biomass of HF was significantly lower under higher temperatures while there was no significant effect of CO2. The mean biomass of the picoflagellates did not respond to temperature while the three nanoflagellate size classes (class limits 3, 5, 8, 15μm) responded negatively to warming while not responding to CO2. The taxon-level results indicate that heterotrophic flagellates do not form a homogenous trophic guild, as often assumed in pelagic food web studies. Instead, the heterotrophic flagellates formed a "food web within the food web". There was a pronounced succession of flagellates leading from a dominance of bacterivores and colloidal matter feeders before the phytoplankton bloom to omnivorous feeders preying upon phytoplankton and heterotrophic flagellates during and after the bloom. This complex intraguild predation patterns probably dampened the response to experimental treatments. PMID:27472657

  11. [Genetic diversity of eukarytic microplankton in different areas of Lake Taihu].

    PubMed

    Chen, Mei-Jun; Kong, Fan-Xiang; Chen, Fei-Zhou; Xing, Peng

    2008-03-01

    The methods of DGGE and cloning/sequencing were used to study the diversity and community structures of small planktons (0.8 - 20 microm) in different areas of Lake Taihu. DGGE indicated that there were markly various fingerprints in different areas and the diversities were higher in areas with low trophic status than those with relatively high trophic status. There were 23, 24 DGGE bands in East Taihu and Gonghu Bay, respectively (Shannon index were 3.135 and 3.178) and 18 bands in both Meiliang Bay and Wuli Bay (Both shannon index were 2.890). The result of cloning/sequencing indicated that there was a high diversity of small planktons in Lake Taihu and most of them phototrophic flagellate, heterotrophic flagellate, ciliate and fungi. There were various community structures in the three different clone libraries. In Meilang Bay, 28.6% OTUs(operational taxonomic unit)belonged to heterotrophic flagellate, followed by Cryptophyta (22.9%) and Chrysophyta (14.3%). In Central Lake, 25.7% OTUs belonged to Chrysophyta, followed by heterotrophic flagellate (20.0%) and Cryptophyta (14.3 %). In East Taihu, ciliates were the dominant group and only a few heterotrophic flagellates (40.9%) were detected. In addition, fungi were relatively abundant (12.2%) in this area. PMID:18649542

  12. Formyl peptide-induced chemotaxis of human polymorphonuclear leukocytes does not require either marked changes in cytosolic calcium or specific granule discharge. Role of formyl peptide receptor reexpression (or recycling).

    PubMed Central

    Perez, H D; Elfman, F; Marder, S; Lobo, E; Ives, H E

    1989-01-01

    We examined the role of intracellular and extracellular calcium on the ability of human polymorphonuclear leukocytes to migrate chemotactically and reexpress (or recycle) formyl peptide receptors when challenged with the synthetic chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP). Extracellular calcium was not required for either optimal chemotactic responses or receptor reexpression. Depletion and chelation of intracellular calcium resulted in significant diminution in the ability of polymorphonuclear leukocytes to release the specific granule constituents lactoferrin and vitamin B12-binding protein during the process of chemotaxis, but had no effect on the capability of these cells to respond chemotactically. Similarly, chelation of intracellular calcium did not affect the ability of these cells to reexpress a population of formyl peptide receptors. Inhibition of receptor reexpression, by a nonagglutinating derivative of wheat-germ agglutinin, was associated with inhibition of chemotactic responses to FMLP. Thus, it appears that large changes in cytosolic free calcium are not necessary for formyl peptide-induced polymorphonuclear leukocyte chemotaxis. In contrast, continuous reexpression (or recycling) of formyl peptide receptors is required for polymorphonuclear leukocyte chemotactic responses to FMLP, a process that appears to be independent from specific granule fusion with plasma membrane. PMID:2723068

  13. Gravitaxis in unicellular microorganisms.

    PubMed

    Hader, D P

    1999-01-01

    Orientation of organisms with respect to the gravitational field of the Earth has been studied for more than 100 years in a number of unicellular microorganisms including flagellates and ciliates. Several hypotheses have been developed how the weak stimulus is perceived. Intracellular statoliths have been found to be involved in gravitaxis of Loxodes, while no specialized organelles have been detected in other ciliates, e.g. Paramecium. Also in the slime mold Physarum no specialized gravireceptors have been identified yet. In the flagellate Euglena gracilis the whole cell body, which is denser than the surrounding medium, seems to act as a statolith pressing onto the lower membrane where it activates mechanosensitive ion channels. Similar results were obtained for the ciliate Paramecium. In contrast to the flagellate Euglena, several ciliates have been found to show gravikinesis, which is defined as a dependence of the swimming velocity on the direction of movement in the gravity field. PMID:11542630

  14. Gravitaxis in unicellular microorganisms

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.

    1999-01-01

    Orientation of organisms with respect to the gravitational field of the Earth has been studied for more than 100 years in a number of unicellular microorganisms including flagellates and ciliates. Several hypotheses have been developed how the weak stimulus is perceived. Intracellular statoliths have been found to be involved in gravitaxis of Loxodes, while no specialized organelles have been detected in other ciliates, e.g. Paramecium. Also in the slime mold Physarum no specialized gravireceptors have been identified yet. In the flagellate Euglena gracilis the whole cell body, which is denser than the surrounding medium, seems to act as a statolith pressing onto the lower membrane where it activates mechanosensitive ion channels. Similar results were obtained for the ciliate Paramecium. In contrast to the flagellate Euglena, several ciliates have been found to show gravikinesis, which is defined as a dependence of the swimming velocity on the direction of movement in the gravity field.

  15. Biochemical characterization of a trypanosomatid isolated from the plant Amaranthus retroflexus.

    PubMed

    Marín, C; Fernández-Ramos, C; Entrala, E; Quesada, J M; Sánchez-Moreno, M

    2000-01-01

    A protozoan flagelate has recently been isolated from Amaranthus retroflexus. This plant grows near economically important crops in southeastern Spain, which are known to be parasitized by Phytomonas spp. The present study focuses on the characterization of the energy metabolism of this new isolate. These flagellates utilize glucose efficiently as their primary energy source, although they are unable to completely degrade it. They excrete ethanol, acetate, glycine, and succinate in lower amount, as well as ammonium. The presence of glycosomes was indicated by the early enzymes of the glycolytic pathway, one enzyme of the glycerol pathway (glycerol kinase), and malate dehydrogenase. No evidence of a fully functional citric-acid cycle was found. In the absence of catalase activity, these flagellates showed significant superoxide dismutase activity located in the glycosomal and cytosolic fractions. These trypanosomes, despite being morphologically and metabolically similar to other Phytomonas isolated from the same area, showed significant differences, suggesting that they are phylogenetically different species. PMID:10998214

  16. Hexamita and Giardia as a cause of mortality in congenitally thymus-less (nude) mice

    PubMed Central

    Boorman, G. A.; Lina, P. H. C.; Zurcher, C.; Nieuwerkerk, H. T. M.

    1973-01-01

    Two intestinal flagellates, Hexamita muris and Giardia muris, were found in high concentrations in most of the congenitally thymus-less (nude) mice in a conventional colony being maintained at the Radiobiological Institute TNO. Antiflagellate therapy markedly reduced mortality, with >50% of the mice living to 110 days. In mice receiving thymus transplants but no antiflagellate treatment the mortality rate was less than in either control or treated mice. In addition, histopathological examination of mice with thymus transplants revealed fewer intestinal flagellates than in control mice. It is suggested that the wasting syndrome seen in nude and neonatally thymectomized mice may be aggravated by infestation with Hexamita and Giardia. PMID:4778720

  17. Phylogenetic position of Cryothecomonas inferred from nuclear-encoded small subunit ribosomal RNA.

    PubMed

    Kühn, S; Lange, M; Medlin, L K

    2000-12-01

    The systematic position of the genus Cryothecomonas has been determined from an analysis of the nuclear-encoded small subunit ribosomal RNA gene of Cryothecomonas longipes and two strains of Cryothecomonas aestivalis. Our phylogenetic trees inferred from maximum likelihood, distance and maximum parsimony methods robustly show that the genus Cryothecomonas clusters within the phylum Cercozoa, and is related to the sarcomonad flagellate Heteromita globosa. Morphological data supporting the taxonomic placement of Cryothecomonas near the sarcomonad flagellates has been compiled from the literature. The high number of nucleotide substitutions found between two morphologically indistinguishable strains of Cryothecomonas aestivalis suggests the possibility of cryptic species within Cryothecomonas aestivalis. PMID:11212894

  18. Tritrichomonas foetus and not Pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhea.

    PubMed

    Levy, Michael G; Gookin, Jody L; Poore, Matthew; Birkenheuer, Adam J; Dykstra, Michael J; Litaker, R Wayne

    2003-02-01

    Recently, several investigators have reported large-bowel diarrhea in cats associated with intestinal trichomonad parasites. These reports have presumptively identified the flagellates as Pentatrichomonas hominis, a n organism putatively capable of infecting the intestinal tracts of a number of mammalian hosts, including cats, dogs, and man. The purpose of the present study was to determine the identity of this recently recognized flagellate by means of rRNA gene sequence analysis; restriction enzyme digest mapping; and light, transmission, and scanning electron microscopy (SEM). PMID:12659310

  19. Phylogenetic position of the genus Perkinsus (Protista, Apicomplexa) based on small subunit ribosomal RNA.

    PubMed

    Goggin, C L; Barker, S C

    1993-07-01

    Parasites of the genus Perkinsus destroy marine molluscs worldwide. Their phylogenetic position within the kingdom Protista is controversial. Nucleotide sequence data (1792 bp) from the small subunit rRNA gene of Perkinsus sp. from Anadara trapezia (Mollusca: Bivalvia) from Moreton Bay, Queensland, was used to examine the phylogenetic affinities of this enigmatic genus. These data were aligned with nucleotide sequences from 6 apicomplexans, 3 ciliates, 3 flagellates, a dinoflagellate, 3 fungi, maize and human. Phylogenetic trees were constructed after analysis with maximum parsimony and distance matrix methods. Our analyses indicate that Perkinsus is phylogenetically closer to dinoflagellates and to coccidean and piroplasm apicomplexans than to fungi or flagellates. PMID:8366895

  20. Complement-derived leukotactic factors in inflammatory synovial fluids of humans

    PubMed Central

    Ward, Peter A.; Zvaifler, Nathan J.

    1971-01-01

    A large per cent of rheumatoid synovial fluids contain chemotactic activity for rabbit granulocytes (neutrophilic). The chemotactic activity is, in large part, related to the fifth (C5) and sixth (C6) components of human complement; a combination of physical-chemical techniques indicates the activity to be attributable to C567 and C5a, a cleavage product of C5. Many rheumatoid synovial fluids contain a C5-cleaving enzyme which, on the basis of substrate specificity and susceptibility to inhibitors, is very similar to an enzyme extractable from lysosomal granules of human and rabbit granulocytes. Inflammatory nonrheumatoid synovial fluids contain chemotactic activity that is related to cleavage products (C3a) of the third component of human complement (C3). Also found in these fluids is a C3-cleaving enzyme capable of producing C3a. Of the other synovial fluids examined, lupus fluids were remarkable by their total lack of chemotactic activity. These findings record for the first time the presence of complement-derived chemotactic factors in pathological human fluids. Images PMID:5545123

  1. Encystment and excystment of kinetoplastid Azumiobodo hoyamushi, causal agent of soft tunic syndrome in ascidian aquaculture.

    PubMed

    Nawata, Akatsuki; Hirose, Euichi; Kitamura, Shin-Ichi; Kumagai, Akira

    2015-08-20

    Soft tunic syndrome in the edible ascidian Halocynthia roretzi is caused by the kinetoplastid flagellate Azumiobodo hoyamushi, which was found to assume a fusiform cell form with 2 flagella in axenic, pure culture. When the flagellate form was incubated in sterilized artificial seawater (pH 8.4), some of the cells became cyst-like and adhered to the bottom of the culture plate. The cyst-like forms were spherical or cuboidal, and each had 2 flagella encapsulated in its cytoplasm. Encystment was also induced in culture medium alkalified to the pH of seawater (8.4) but not in unmodified (pH 7.2) or acidified media (pH 6.4). More than 95% of the cyst-like cells converted to the flagellate form within 1 d following transfer to seawater containing ascidian tunic extracts from host ascidians. The cyst-like cells were able to survive in seawater with no added nutrients for up to 2 wk at 20°C and for a few months at 5 to 15°C. The survival period in seawater depended on temperature: some cyst-like cells survived 3 mo at 10°C, and ca. 95% of these converted to flagellate forms in seawater containing tunic extracts. Thus, A. hoyamushi is able to persist under adverse conditions in a cyst-like form able to adhere to organic and inorganic substrata for protracted periods of time. PMID:26290510

  2. Construction, expression, purification and antigenicity of recombinant Campylobacter jejuni flagellar proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Campylobacter jejuni, a flagellated, spiral-rod Gram-negative bacterium, is the leading etiologic agent of human acute bacterial gastroenteritis worldwide. The source of this microorganism for human infection has been implicated as consumption and handling of poultry meat where this microorganism i...

  3. Protistan communities in aquifers: a review.

    PubMed

    Novarino, G; Warren, A; Butler, H; Lambourne, G; Boxshall, A; Bateman, J; Kinner, N E; Harvey, R W; Mosse, R A; Teltsch, B

    1997-07-01

    Eukaryotic microorganisms (protists) are a very important component of microbial communities inhabiting groundwater aquifers. This is not unexpected when one considers that many protists feed heterotrophically, by means of either phagotrophy (bacterivory) or osmotrophy. Protistan numbers are usually low (< 10(2) per g dw of aquifer material) in pristine, uncontaminated aquifers but may increase by several orders of magnitude in aquifers subject to organic pollution. Small flagellates (typically 2-3(5) microns in size in situ) are by far the dominant protists in aquifers, although amoebae and occasionally ciliates may also be present in much lower numbers. Although a wealth of new taxonomic information is waiting to be brought to light, interest in the identity of aquifer protists is not exclusively academic. If verified, the following hypotheses may prove to be important towards our understanding of the functioning of microbial communities in aquifers: (1) Differences in swimming behavior between species of flagellates lead to feeding heterogeneity and niche differentiation, implying that bacterivorous flagellates graze on different subsets of the bacterial community, and therefore play different roles in controlling bacterial densities. (2) Bacterivorous flagellates grazing on bacteria capable of degrading organic compounds have an indirect effect on the overall rates of biodegradation. PMID:9299706

  4. Wood degradation in the digestive tract of the Formosan subterranean termite (Isoptera: Rhinotermitidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most wood decomposition in the digestive tract of subterranean termite workers occurs in food vacuoles of flagellate protozoan symbionts in the hindgut. This study uses scanning electron microscopy to analyze the degree of degradation of wood particles in different regions of the termite gut. Gut co...

  5. Secondary metabolite production by Pseudomonas fluorescens strain Pf-5 confers protection against Naegleria americana in the wheat rhizosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteria employ a variety of morphological and metabolic mechanisms to avoid protozoan predation. In Pseudomonas fluorescens strains SS101 and SBW25, cyclic lipopeptide (CLP) production served as a defense mechanism that limited predation by the amoeba-flagellate Naegleria americana, and secondary m...

  6. Flagella-Mediated Differences in Deposition Dynamics for Azotobacter vinelandii in Porous Media

    SciTech Connect

    Lu, Nanxi; Bevard, Tara; Massoudieh, Arash; Zhang, Changyong; Dohnalkova, Alice; Zilles, Julie L.; Nguyen, Thanh H.

    2013-05-21

    A multi-scale approach was designed to investigate deposition of flagellated and non-flagellated strains of Azotobacter vinelandii in porous media. In a radial stagnation point flow cell (RSPF), the deposition rate of the flagellated strain (DJ77) on quartz was higher than that of the non-flagellated (Fla-) strain. In contrast, deposition of the Fla- strain exceeded that of DJ77 in two-dimensional silicon microfluidic models (micromodels) and in columns packed with glass beads. Direct cell counts in micromodel experiments showed decreasing values of clean collector removal efficiencies over time, suggesting that approaching cells were blocked from deposition by cells already attached to the collector surface. Column breakthrough curves for both strains also showed a decrease in deposition rates with time. Modeling results showed that blocking becomes effective for DJ77 strain at lower ionic strengths (1mM and 10mM), while for Fla- strain blocking was similar at all ionic strengths. In later stages of micromodel experiments, a ripening effect was also observed, where cells preferentially attached to already attached cells. Ripening happened earlier with the Fla- strain, which suggested that flagella interfered with ripening. Different mechanisms dominate at different stages of bacteria transport in porous media.

  7. Bleomycin Containing Chemotherapeutic Regimen Induced Acquired Partial Lipodystrophy

    PubMed Central

    Tandon, Vishal R; Gupte, Novy; Mahajan, Vivek; Sharma, Rahul; Langer, Cheena; Khajuria, Vijay; Mahajan, Annil

    2016-01-01

    Bleomycin toxicity predominantly affects the skin and lungs. Cutaneous toxicity classically known to present with bleomycin are flagellate erythema and drug rash. We hereby report an isolated case of (bleomyicn)-induced acquired partial (lipodytrophy) having potential cosmetic implications in a young women prescribed postoperatively following a case of germ cell carcinoma of ovary (endodermal sinus tumor). PMID:26955139

  8. Effects of Selected Rhizosphere Microorganisms and Carbon on Soybean Cyst Nematode Population Density and Reproduction in Different Tillage Regimes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean cyst nematode (SCN) population density can be influenced by tillage practices. Data were collected over two growing seasons on total and active bacteria, total and active fungi, and protozoans (amobae, flagellates, ciliates) in the soybean rhizosphere to determine whether the levels of these...

  9. Simulation and Experiment of Extinction or Adaptation of Biological Species after Temperature Changes

    NASA Astrophysics Data System (ADS)

    Stauffer, D.; Arndt, H.

    Can unicellular organisms survive a drastic temperature change, and adapt to it after many generations? In simulations of the Penna model of biological aging, both extinction and adaptation were found for asexual and sexual reproduction as well as for parasex. These model investigations are the basis for the design of evolution experiments with heterotrophic flagellates.

  10. Visceral leishmaniasis with cutaneous symptoms in a patient treated with infliximab followed by fatal consequences.

    PubMed

    Juzlova, Katerina; Votrubova, Jana; Kacerovska, Denisa; Lukas, Milan; Bortlik, Martin; Rohacova, Hana; Nohynkova, Eva; Vojackova, Nadezda; Fialova, Jorga; Hercogova, Jana

    2014-01-01

    Leishmaniasis is an infectious disease caused by parasitic flagellates of the genus Leishmania. The authors present a case of 44-year-old man with Crohn's disease treated successfully with infliximab. This case report shows rare visceral leishmaniasis with cutaneous symptoms in an immunocompromised patient. Skin manifestations may occur before or after the visceral infection and they are often diverse. PMID:24903470

  11. Resistance to Powdery Scab in Potato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery scab is a serious disease of potato that is among the most damaging emerging potato pathogens throughout the world. Twenty years ago it was rarity in the Columbia Basin but today it is widespread, damaging and a threat to the profitability of the industry. Flagellated zoospores which swim ...

  12. An outbreak of Plesimonus Shigelloides in Zebrafish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plesiomonas shigelloides is a flagellated, gram-negative rod that is an emergent pathogen associated with human gastroenteritis. Recently, we experienced a disease outbreak in zebrafish that were obtained from a commercial source. Fourteen days after being held at 27°C in our flow-through quarantine...

  13. Acetylcholinesterase of the Sand Fly Phlebotomus papatasi (Scopoli): cDNA Sequence, Baculovirus Expression and Biochemical Properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of people and domestic animals around the world are affected by leishmaniasis, a disease caused by various species of flagellated protozoans in the genus Leishmania that are transmitted by several sand fly species. Insecticides are widely used for sand fly population control to try to reduc...

  14. Effectiveness of copper sulfate, potassium permanganate, and peracetic acid to reduce mortality and infestation of Ichthyobodo nector in channel catfish Ictalurus punctatus (Rafinesque 1818)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ichthyobodo necator is a single celled bi-flagellate parasite, and in high density can causes significant mortality in young fish. Copper sulfate (CuSO4), potassium permanganate (KMnO4) and peracetic acid (PAA) were evaluated for effectiveness against ichthyobodosis. Treatments were: untreated con...

  15. Magnetic Propulsion of Microswimmers with DNA-Based Flagellar Bundles

    PubMed Central

    2016-01-01

    We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials. PMID:26821214

  16. Trichodina ctenophorii n. sp., a novel symbiont of ctenophores of the northern coast of the Gulf of Mexico.

    PubMed

    Estes, A M; Reynolds, B S; Moss, A G

    1997-01-01

    Peritrich ciliates of the genus Trichodina are internal or external symbionts of invertebrate and vertebrate hosts. We describe here Trichodina ctenophorii n. sp., a symbiont of Mnemiopsis mccraydii and Beroë ovata (Phylum Ctenophora). The morphology of fixed and living specimens is revealed by silver impregnation, scanning electron microscopy, and differential interference microscopy. Distinguishing features of Trichodina ctenophorii include a denticular morphology composed of falcate, blunt-tipped blades, and long, straight thorns, with five pins per denticle. Trichodina ctenophorii is found only on the comb plates of these ctenophores. To the best of our knowledge, this is the first report of a trichodinid from the Gulf of Mexico and the first associated with ctenophores. PMID:9304811

  17. Complete genome sequence of Conexibacter woesei type strain (ID131577T)

    PubMed Central

    Pukall, Rüdiger; Lapidus, Alla; Glavina Del Rio, Tijana; Copeland, Alex; Tice, Hope; Cheng, Jan-Fang; Lucas, Susan; Chen, Feng; Nolan, Matt; Bruce, David; Goodwin, Lynne; Pitluck, Sam; Mavromatis, Konstantinos; Ivanova, Natalia; Ovchinnikova, Galina; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Land, Miriam; Hauser, Loren; Chang, Yun-Juan; Jeffries, Cynthia D.; Chain, Patrick; Meincke, Linda; Sims, David; Brettin, Thomas; Detter, John C.; Rohde, Manfred; Göker, Markus; Bristow, Jim; Eisen, Jonathan A.; Markowitz, Victor; Kyrpides, Nikos C.; Klenk, Hans-Peter; Hugenholtz, Philip

    2010-01-01

    The genus Conexibacter (Monciardini et al. 2003) represents the type genus of the family Conexibacteraceae (Stackebrandt 2005, emend. Zhi et al. 2009) with Conexibacter woesei as the type species of the genus. C. woesei is a representative of a deep evolutionary line of descent within the class Actinobacteria. Strain ID131577T was originally isolated from temperate forest soil in Gerenzano (Italy). Cells are small, short rods that are motile by peritrichous flagella. They may form aggregates after a longer period of growth and, then as a typical characteristic, an undulate structure is formed by self-aggregation of flagella with entangled bacterial cells. Here we describe the features of the organism, together with the complete sequence and annotation. The 6,359,369 bp long genome of C. woesei contains 5,950 protein-coding and 48 RNA genes and is part of the Genomic Encyclopedia of Bacteria and Archaea project. PMID:21304704

  18. Observed frequency-independent torque in flagellar bacterial motors optimizes space exploration.

    PubMed

    Di Salvo, Mario E; Condat, C A

    2012-12-01

    A surprising feature of many bacterial motors is the apparently conserved form of their torque-frequency relation. Experiments indicate that the torque provided by the bacterial rotary motor is approximately constant over a large range of angular speeds. This is observed in both monotrichous and peritrichous bacteria, independently of whether they are propelled by a proton flux or by a Na(+) ion flux. If the relation between angular speed ω and swimming speed is linear, a ω-independent torque implies that the power spent in active motion is proportional to the instantaneous bacterial speed. Using realistic values of the relevant parameters, we show that a constant torque maximizes the volume of the region explored by a bacterium in a resource-depleted medium. Given that nutrients in the ocean are often concentrated in separate, ephemeral patches, we propose that the observed constancy of the torque may be a trait evolved to maximize bacterial survival in the ocean. PMID:23367976

  19. Magnetic Propulsion of Microswimmers with DNA-Based Flagellar Bundles.

    PubMed

    Maier, Alexander M; Weig, Cornelius; Oswald, Peter; Frey, Erwin; Fischer, Peer; Liedl, Tim

    2016-02-10

    We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials. PMID:26821214

  20. Zipping and entanglement in flagellar bundle of E. coli: Role of motile cell body

    NASA Astrophysics Data System (ADS)

    Adhyapak, Tapan Chandra; Stark, Holger

    2015-11-01

    The course of a peritrichous bacterium, such as E. coli, crucially depends on the level of synchronization and self-organization of several rotating flagella. However, the rotation of each flagellum generates countermovements of the body which in turn affect the flagellar dynamics. Using a detailed numerical model of an E. coli, we demonstrate that flagellar entanglement, besides fluid flow relative to the moving body, dramatically changes the dynamics of flagella from that compared to anchored flagella. In particular, bundle formation occurs through a zipping motion in a remarkably rapid time, affected little by initial flagellar orientation. A simplified analytical model supports our observations. Finally, we illustrate how entanglement, hydrodynamic interactions, and body movement contribute to zipping and bundling.

  1. Mixed populations of marine microalgae in continuous culture: Factors affecting species dominance and biomass productivity.

    PubMed

    Regan, D L; Ivancic, N

    1984-11-01

    Marine microalgae were grown in multispecies continuous cultures. Under carbon dioxide limitation, blue-green algae dominated. Under nitrate and light limitation, species dominance depended on the initial conditions. When the inoculum consisted primarily of blue-green algae with smaller amounts of other species, blue-green algae and pennate diatoms dominated. When the inoculum consisted of equal amounts of all species, green flagellates and pennate diatoms dominated. Green flagellates and blue-green algae were incompatible and never shared dominance. When nutrient limitations were overcome, the productivity of seawater was increased 100-fold before light limitation occurred. The productivity could be further increased by reducing photorespiration in the culture. The dilution rates studied (0.1, 0.2, and 0.4 day(-1)) had no effect on species dominance, nor did the higher dilution rates select for smaller cells. The maximum productivity occurred at a dilution rate of 0.2 day(-1). Temperature had the greatest effect on species dominance, with green flagellates, pennate diatoms, and blue-green algae dominating at 20 degrees C and only blue-green algae dominating at 35 degrees C. The productivity at 35 degrees C was lower than that at 20 degrees C because of the lower solubility of carbon dioxide at higher temperatures. At 10% salinity, green flagellates and pennate diatoms dominated. The productivity at this salinity was 50% that obtained at the salinity of seawater (3.5%). At 25% salinity, only the green flagellate, Dunaliella salina, survived at a productivity of 1% that obtained at the salinity of seawater. PMID:18551649

  2. Multigene eukaryote phylogeny reveals the likely protozoan ancestors of opisthokonts (animals, fungi, choanozoans) and Amoebozoa.

    PubMed

    Cavalier-Smith, Thomas; Chao, Ema E; Snell, Elizabeth A; Berney, Cédric; Fiore-Donno, Anna Maria; Lewis, Rhodri

    2014-12-01

    Animals and fungi independently evolved from the protozoan phylum Choanozoa, these three groups constituting a major branch of the eukaryotic evolutionary tree known as opisthokonts. Opisthokonts and the protozoan phylum Amoebozoa (amoebae plus slime moulds) were previously argued to have evolved independently from the little-studied, largely flagellate, protozoan phylum, Sulcozoa. Sulcozoa are a likely evolutionary link between opisthokonts and the more primitive excavate flagellates that have ventral feeding grooves and the most primitive known mitochondria. To extend earlier sparse evidence for the ancestral (paraphyletic) nature of Sulcozoa, we sequenced transcriptomes from six gliding flagellates (two apusomonads; three planomonads; Mantamonas). Phylogenetic analyses of 173-192 genes and 73-122 eukaryote-wide taxa show Sulcozoa as deeply paraphyletic, confirming that opisthokonts and Amoebozoa independently evolved from sulcozoans by losing their ancestral ventral groove and dorsal pellicle: Apusozoa (apusomonads plus anaerobic breviate amoebae) are robustly sisters to opisthokonts and probably paraphyletic, breviates diverging before apusomonads; Varisulca (planomonads, Mantamonas, and non-gliding flagellate Collodictyon) are sisters to opisthokonts plus Apusozoa and Amoebozoa, and possibly holophyletic; Glissodiscea (planomonads, Mantamonas) may be holophyletic, but Mantamonas sometimes groups with Collodictyon instead. Taxon and gene sampling slightly affects tree topology; for the closest branches in Sulcozoa and opisthokonts, proportionally reducing missing data eliminates conflicts between homogeneous-model maximum-likelihood trees and evolutionarily more realistic site-heterogeneous trees. Sulcozoa, opisthokonts, and Amoebozoa constitute an often-pseudopodial 'podiate' clade, one of only three eukaryotic 'supergroups'. Our trees indicate that evolution of sulcozoan dorsal pellicle, ventral pseudopodia, and ciliary gliding (probably simultaneously

  3. A multigene phylogeny of Olpidium and its implications for early fungal evolution

    PubMed Central

    2011-01-01

    Background From a common ancestor with animals, the earliest fungi inherited flagellated zoospores for dispersal in water. Terrestrial fungi lost all flagellated stages and reproduce instead with nonmotile spores. Olpidium virulentus (= Olpidium brassicae), a unicellular fungus parasitizing vascular plant root cells, seemed anomalous. Although Olpidium produces zoospores, in previous phylogenetic studies it appeared nested among the terrestrial fungi. Its position was based mainly on ribosomal gene sequences and was not strongly supported. Our goal in this study was to use amino acid sequences from four genes to reconstruct the branching order of the early-diverging fungi with particular emphasis on the position of Olpidium. Results We concatenated sequences from the Ef-2, RPB1, RPB2 and actin loci for maximum likelihood and Bayesian analyses. In the resulting trees, Olpidium virulentus, O. bornovanus and non-flagellated terrestrial fungi formed a strongly supported clade. Topology tests rejected monophyly of the Olpidium species with any other clades of flagellated fungi. Placing Olpidium at the base of terrestrial fungi was also rejected. Within the terrestrial fungi, Olpidium formed a monophyletic group with the taxa traditionally classified in the phylum Zygomycota. Within Zygomycota, Mucoromycotina was robustly monophyletic. Although without bootstrap support, Monoblepharidomycetes, a small class of zoosporic fungi, diverged from the basal node in Fungi. The zoosporic phylum Blastocladiomycota appeared as the sister group to the terrestrial fungi plus Olpidium. Conclusions This study provides strong support for Olpidium as the closest living flagellated relative of the terrestrial fungi. Appearing nested among hyphal fungi, Olpidium's unicellular thallus may have been derived from ancestral hyphae. Early in their evolution, terrestrial hyphal fungi may have reproduced with zoospores. PMID:22085768

  4. N-Formylmethionyl Peptide Receptors on Equine Leukocytes Initiate Secretion but not Chemotaxis

    NASA Astrophysics Data System (ADS)

    Snyderman, Ralph; Pike, Marilyn C.

    1980-07-01

    The chemotaxis of leukocytes appears to be initiated by the binding of chemotactic factors to the surface of these cells. N-Formylated peptides induce chemotaxis and lysosomal enzyme secretion of leukocytes; because these peptides are available in a purified radiolabeled form, they have been useful in the characterization of receptors for chemotactic factors. Equine polymorphonuclear leukocytes secrete lysosomal enzymes but do not exhibit chemotaxis in response to the N-formylated peptides, even though they have a high-affinity cell surface receptor for these agents. The specificity of the equine receptor resembles the specificity of the receptor on chemotactically responsive leukocytes from other species. Equine polymorphonuclear leukocytes may thus be an excellent model for the study of the events that lead to a biological response following receptor occupancy.

  5. Functions of granulocytes and monocytes in primary biliary and alcoholic cirrhosis.

    PubMed Central

    Blussé van Oud, A; Janssens, A R; Leijh, P C; van Furth, R

    1985-01-01

    Granulocytes and monocytes from patients with primary biliary cirrhosis (PBC) and alcoholic cirrhosis (AC) were investigated with respect to the major functional activities involved in host defence against micro-organisms. Chemokinesis, chemotaxis, phagocytosis, and intracellular killing of micro-organisms as well as the ability of these cells to consume O2 and convert it to H2O2 were all comparable to those of granulocytes and monocytes of healthy donors. Investigation of sera of PBC and AC patients revealed normal opsonic activity in sera from both sources and normal chemotactic activity in PBC sera. Compared with normal donor serum AC sera were less chemotactic for granulocytes but not for monocytes. This diminished chemotactic activity is probably ascribable to the presence of a specific inhibitor of granulocyte chemotaxis in AC serum. Taken together, these results indicate that a postulated defective functioning of phagocytic cells can not explain the frequent and serious infections observed in patients with chronic liver disorders. PMID:4085152

  6. Elastin fragments drive disease progression in a murine model of emphysema

    PubMed Central

    Houghton, A. McGarry; Quintero, Pablo A.; Perkins, David L.; Kobayashi, Dale K.; Kelley, Diane G.; Marconcini, Luiz A.; Mecham, Robert P.; Senior, Robert M.; Shapiro, Steven D.

    2006-01-01

    Mice lacking macrophage elastase (matrix metalloproteinase-12, or MMP-12) were previously shown to be protected from the development of cigarette smoke–induced emphysema and from the accumulation of lung macrophages normally induced by chronic exposure to cigarette smoke. To determine the basis for macrophage accumulation in experimental emphysema, we now show that bronchoalveolar lavage fluid from WT smoke-exposed animals contained chemotactic activity for monocytes in vitro that was absent in lavage fluid from macrophage elastase–deficient mice. Fractionation of the bronchoalveolar lavage fluid demonstrated the presence of elastin fragments only in the fractions containing chemotactic activity. An mAb against elastin fragments eliminated both the in vitro chemotactic activity and cigarette smoke–induced monocyte recruitment to the lung in vivo. Porcine pancreatic elastase was used to recruit monocytes to the lung and to generate emphysema. Elastin fragment antagonism in this model abrogated both macrophage accumulation and airspace enlargement. PMID:16470245

  7. Soluble Pityrosporum-derived chemoattractant for polymorphonuclear leukocytes of psoriatic patients.

    PubMed

    Bunse, T; Mahrle, G

    1996-01-01

    The chemoattraction of polymorphonuclear leukocytes (PMNs) from psoriatic patients, atopic patients and healthy control persons by Pityrosporum orbicularelovale was investigated using the Boyden chamber method. The chemotactical attraction of PMNs from psoriatic patients by Pityrosporum (stimulation index SI = 58 +/- 50) was significantly increased (p < 0.05) compared to PMNs from atopic patients (SI = 20 +/- 17) and control persons (SI = 26 +/- 24). This effect seems to be specific for Pityrosporum, since the chemotactical response to Staphylococcus epidermidis was not increased in psoriasis. The chemotactical factor produced by Pityrosporum is hydrophilic and is destroyed by acid hydrolysis, indicating its protein nature. The yeast Pityrosporum may thus play a role in the koebnerization of psoriasis. PMID:8721481

  8. The Vi Capsular Polysaccharide Enables Salmonella enterica Serovar Typhi to Evade Microbe-Guided Neutrophil Chemotaxis

    PubMed Central

    Wangdi, Tamding; Lee, Cheng-Yuk; Spees, Alanna M.; Yu, Chenzhou; Kingsbury, Dawn D.; Winter, Sebastian E.; Hastey, Christine J.; Wilson, R. Paul

    2014-01-01

    Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever, a disseminated infection, while the closely related pathogen S. enterica serovar Typhimurium (S. Typhimurium) is associated with a localized gastroenteritis in humans. Here we investigated whether both pathogens differ in the chemotactic response they induce in neutrophils using a single-cell experimental approach. Surprisingly, neutrophils extended chemotactic pseudopodia toward Escherichia coli and S. Typhimurium, but not toward S. Typhi. Bacterial-guided chemotaxis was dependent on the presence of complement component 5a (C5a) and C5a receptor (C5aR). Deletion of S. Typhi capsule biosynthesis genes markedly enhanced the chemotactic response of neutrophils in vitro. Furthermore, deletion of capsule biosynthesis genes heightened the association of S. Typhi with neutrophils in vivo through a C5aR-dependent mechanism. Collectively, these data suggest that expression of the virulence-associated (Vi) capsular polysaccharide of S. Typhi obstructs bacterial-guided neutrophil chemotaxis. PMID:25101794

  9. Streptococcus salivarius strains carry either fibrils or fimbriae on the cell surface.

    PubMed Central

    Handley, P S; Carter, P L; Fielding, J

    1984-01-01

    Strains of Streptococcus salivarius were screened by negative staining for the presence of surface structures. Two structural subgroups were found, carrying either fibrils or fimbriae, projecting from the cell surface. Eight strains carried a very dense peritrichous array of fibrils of two distinct lengths. Long fibrils had an average length of 175 nm, and short fibrils had an average length of 95 nm. Two strains carried only long fibrils, one strain carried only short fibrils, and another strain carried a lateral tuft of very prominent fibrils of two lengths, with a fibrillar fuzz covering the remainder of the cell surface. In all the strains in which they were present, the long fibrils were unaffected by protease or trypsin treatment. In contrast, the short fibrils were completely digested by protease and partially removed by trypsin. Neither long nor short fibrils were affected structurally by mild pepsin digestion or by lipase. The Lancefield extraction procedure removed both long and short fibrils. These twelve fibrillar strains were therefore divisible into four structural subgroups. Extracts of all the fibrillar strains reacted with group K antiserum. The second main structural subgroup consisted of nine strains of S. salivarius, all of which carried morphologically identical, flexible fimbriae arranged peritrichously over the cell surface. The fimbriae were structurally distinct from fibrils and measured 0.5 to 1.0 micron long and 3 to 4 nm wide, with an irregular outline and no obvious substructure. There was no obvious reduction in the number of fimbriae after protease or trypsin treatment. Extracts of the fimbriated strains did not react with the group K antiserum. The two serological and structural subgroups could also be distinguished by colony morphology. Images PMID:6197404

  10. The microbial community of Ophrydium versatile colonies: endosymbionts, residents, and tenants

    NASA Technical Reports Server (NTRS)

    Duval, B.; Margulis, L.

    1995-01-01

    Ophrydium versatile is a sessile peritrichous ciliate (Kingdom Protoctista, class Oligohymenophora, order Peritrichida, suborder Sessilina) that forms green, gelatinous colonies. Chlorophyll a and b impart a green color to Ophrydium masses due to 400-500 Chlorella-like endosymbionts in each peritrich. Ophrydium colonies, collected from two bog wetlands (Hawley and Leverett, Massachusetts) were analyzed for their gel inhabitants. Other protists include ciliates, mastigotes, euglenids, chlorophytes, and heliozoa. Routine constituents include from 50-100,000 Nitzschia per ml of gel and at least four other diatom genera (Navicula, Pinnularia, Gyrosigma, Cymbella) that may participate in synthesis of the gel matrix. Among the prokaryotes are filamentous and coccoid cyanobacteria, large rod-shaped bacteria, at least three types of spirochetes and one unidentified Saprospira-like organism. Endosymbiotic methanogenic bacteria, observed using fluorescence microscopy, were present in unidentified hypotrichous ciliates. Animals found inside the gel include rotifers, nematodes, and occasional copepods. The latter were observed in the water reservoir of larger Ophrydium masses. From 30-46% of incident visible radiation could be attenuated by Ophrydium green jelly masses in laboratory observations. Protargol staining was used to visualize the elongate macronuclei and small micronucleus of O. versatile zooids and symbiotic algal nuclei. Electron microscopic analysis of the wall of the Chlorella-like symbiont suggests that although the Ophrydium zooids from British Columbia harbor Chlorella vulgaris, those from Hawley Bog contain Graesiella sp. The growth habit in the photic zone and loose level of individuation of macroscopic Ophrydium masses are interpretable as extant analogs of certain Ediacaran biota: colonial protists in the Vendian fossil record.

  11. The microbial community of Ophrydium versatile colonies: endosymbionts, residents, and tenants.

    PubMed

    Duval, B; Margulis, L

    1995-01-01

    Ophrydium versatile is a sessile peritrichous ciliate (Kingdom Protoctista, class Oligohymenophora, order Peritrichida, suborder Sessilina) that forms green, gelatinous colonies. Chlorophyll a and b impart a green color to Ophrydium masses due to 400-500 Chlorella-like endosymbionts in each peritrich. Ophrydium colonies, collected from two bog wetlands (Hawley and Leverett, Massachusetts) were analyzed for their gel inhabitants. Other protists include ciliates, mastigotes, euglenids, chlorophytes, and heliozoa. Routine constituents include from 50-100,000 Nitzschia per ml of gel and at least four other diatom genera (Navicula, Pinnularia, Gyrosigma, Cymbella) that may participate in synthesis of the gel matrix. Among the prokaryotes are filamentous and coccoid cyanobacteria, large rod-shaped bacteria, at least three types of spirochetes and one unidentified Saprospira-like organism. Endosymbiotic methanogenic bacteria, observed using fluorescence microscopy, were present in unidentified hypotrichous ciliates. Animals found inside the gel include rotifers, nematodes, and occasional copepods. The latter were observed in the water reservoir of larger Ophrydium masses. From 30-46% of incident visible radiation could be attenuated by Ophrydium green jelly masses in laboratory observations. Protargol staining was used to visualize the elongate macronuclei and small micronucleus of O. versatile zooids and symbiotic algal nuclei. Electron microscopic analysis of the wall of the Chlorella-like symbiont suggests that although the Ophrydium zooids from British Columbia harbor Chlorella vulgaris, those from Hawley Bog contain Graesiella sp. The growth habit in the photic zone and loose level of individuation of macroscopic Ophrydium masses are interpretable as extant analogs of certain Ediacaran biota: colonial protists in the Vendian fossil record. PMID:11539474

  12. Chemotaxis during neural crest migration.

    PubMed

    Shellard, Adam; Mayor, Roberto

    2016-07-01

    Chemotaxis refers to the directional migration of cells towards external, soluble factors along their gradients. It is a process that is used by many different cell types during development for tissue organisation and the formation of embryonic structures, as well as disease like cancer metastasis. The neural crest (NC) is a multipotent, highly migratory cell population that contribute to a range of tissues. It has been hypothesised that NC migration, at least in part, is reliant on chemotactic signals. This review will explore the current evidence for proposed chemoattractants of NC cells, and outline mechanisms for the chemotactic response of the NC to them. PMID:26820523

  13. Modulation of human eosinophil polymorphonuclear leukocyte migration and function.

    PubMed Central

    Goetzl, E. J.

    1976-01-01

    Eosinophil migration toward a concentration gradient of a chemotactic factor is regulated at four levels. Diverse immunologic pathways generate stimuli with eosinophil chemotactic activity, including the complement products C5a and a fragment of C3a and the peptide products of mast cells and basophils activated by IgE-mediated reactions, such as eosinophil chemotactic factor of anaphylaxis (ECF-A) and other oligopeptides. The intrinsic preferential leukocyte activity of the chemotactic stimuli represents the second level of modulation, with ECF-A and other mast cell-derived peptides exhibiting the most selective action on eosinophils. The third level of control of eosinophil chemotaxis is composed of inactivators and inhibitors of chemotactic stimuli and is exemplified by degradation of C5a by anaphylatoxin inactivator or chemotactic factor inactivator and of ECF-A by carboxypeptidase-A or aminopeptidases. The activity of ECF-A is uniquely suppressed by equimolar quantities of its NH2- terminal tripeptide substituent, presumably by eosinophil membrane receptor competition. Factors comprising the fourth level of regulation, which alter eosinophil responsiveness to chemotactic stimuli, include the chemotactic factors themselves, through deactivation; nonchemotactic inhibitors such as the COOH-terminal tripeptide substituent of ECF-A, the neutrophil-immobilizing factor (NIF), the phagocytosis-enhancing factor Thr-Lys-Pro-Arg, and histamine at concentrations greater than 400 ng/ml; and nonchemotactic enhancing principles represented by ascorbate and by histamine at concentrations of 30 ng/ml or less. Local concentrations of eosinophils called to and immobilized at the site of a hypersenitivity reaction may express their regulatory functions by degrading the chemical mediators elaborated including histamine, slow-reacting substance of anaphylaxis (SRS-A), and platelet-activating factor (PAF) by way of their content of histaminase, arylsulfatase B, and phospholipase D

  14. Biological soliton in multicellular movement

    NASA Astrophysics Data System (ADS)

    Kuwayama, Hidekazu; Ishida, Shuji

    2013-07-01

    Solitons have been observed in various physical phenomena. Here, we show that the distinct characteristics of solitons are present in the mass cell movement of non-chemotactic mutants of the cellular slime mould Dictyostelium discoideum. During starvation, D. discoideum forms multicellular structures that differentiate into spore or stalk cells and, eventually, a fruiting body. Non-chemotactic mutant cells do not form multicellular structures; however, they do undergo mass cell movement in the form of a pulsatile soliton-like structure (SLS). We also found that SLS induction is mediated by adhesive cell-cell interactions. These observations provide novel insights into the mechanisms of biological solitons in multicellular movement.

  15. Metal quotas of plankton in the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Twining, Benjamin S.; Baines, Stephen B.; Bozard, James B.; Vogt, Stefan; Walker, Elyse A.; Nelson, David M.

    2011-03-01

    The micronutrient metals Mn, Fe, Co, Ni and Zn are required for phytoplankton growth, and their availability influences ocean productivity and biogeochemistry. Here we report the first direct measurements of these metals in phytoplankton and protozoa from the equatorial Pacific Ocean. Cells representing 4 functional groups (diatoms, autotrophic flagellates, heterotrophic flagellates and autotrophic picoplankton) were collected from the surface mixed layer using trace-metal clean techniques during transects across the equator at 110°W and along the equator between 110°W and 140°W. Metal quotas were determined for individual cells with synchrotron x-ray fluorescence microscopy, and cellular stoichiometries were calculated relative to measured P and S, as well as to C calculated from biovolume. Bulk particulate (>3 μm) metal concentrations were also determined at 3 stations using inductively coupled plasma mass spectrometry for comparison to single-cell stoichiometries. Phosphorus-normalized Mn, Fe, Ni and Zn ratios were significantly higher in diatoms than other cell types, while Co stoichiometries were highest in autotrophic flagellates. The magnitude of these effects ranged from approximately 2-fold for Mn in diatoms and autotrophic flagellates to nearly an order of magnitude for Fe in diatoms and picoplankton. Variations in S-normalized metal stoichiometries were also significant but of lower magnitude (1.4 to 6-fold). Cobalt and Mn quotas were 1.6 and 3-fold higher in autotrophic than heterotrophic flagellates. Autotrophic picoplankton were relatively enriched in Ni but depleted in Zn, matching expectations based on known uses of these metals in prokaryotes and eukaryotes. Significant spatial variability in metal stoichiometries was also observed. At two stations deviations in Fe stoichiometries reflected features in the dissolved Fe distribution. At these same stations, high Ni stoichiometries in autotrophic flagellates were correlated with elevated ammonium

  16. The emergence of a new chlorophytan system, and Dr. Kornmann's contribution thereto

    NASA Astrophysics Data System (ADS)

    van den Hoek, C.; Stam, W. T.; Olsen, J. L.

    1988-09-01

    In traditional chlorophytan systems the organizational level was the primary character for the distinction of main groups (classes and orders). For instance, in Fott (1971), the flagellate level corresponds with the Volvocales, the coccoid level with the Chlorococcales, the filamentous level with the Ulotrichales, the siphonocladous level with the Siphonocladales, and the siphonous level with the Bryopsidales. The new system presented here is an elaboration and emendation of recently proposed taxonomies and their underlying phylogenetic hypotheses, and it is mainly based on ultrastructural features which have become available over the last 15 years. The following criteria are used for the distinction of classes and orders: (1) architecture of the flagellate cell (flagellate cells are considered as the depositories of primitive characters); (2) type of mitosis-cytokinesis; (3) place of meiosis in the life history and, consequently, the sexual life history type; (4) organizational level and thallus architecture; (5) habitat type (marine versus feshwater and terrestrial); (6) chloroplast type. The following classes are presented: Prasinophyceae, Chlamydophyceae, Ulvophyceae (orders Codiolales, Ulvales, Cladophorales, Bryopsidales, Dasycladales), Pleurastrophyceae (?), Chlorophyceae s.s. (orders Cylindrocapsales, Oedogoniales, Chaetophorales), Zygnematophyceae, Trentepohliophyceae, Charophyceae (orders Klebsormidiales, Coleochaetales, Charales). The new system no longer reflects the traditional hypothesis of a stepwise evolutionary progression of organizational levels in which the flagellate level represents the most primitive lineage, the coccoid and sarcinoid levels lineages of intermediate derivation, and the filamentous, siphonocladous and siphonous levels the most derived lineages. Instead, it is now hypothesized that these levels have arisen over and over again in different chlorophytan lineages which are primarily characterized by their type of flagellate cell

  17. COMPARATIVE STUDIES OF HERPETOMONADS AND LEISHMANIAS

    PubMed Central

    Noguchi, Hideyo; Tilden, Evelyn B.

    1926-01-01

    Nine strains of herpetomonads have been isolated in pure culture from eight varieties of insects, and three strains from two species of plants. Four of the cultures were derived from latex-feeding insects (Oncopeltus fasciatus, Oncopeltus sp. ?, Lygæus kalmii) and three from latex plants (Asclepias syriaca, Asclepias nivea), two from mosquitoes (Culex pipiens and Anopheles quadrimaculatus), one from the house fly (Musca domestica), and two from bluebottle flies. In addition impure cultures have been obtained from Oncopeltus cingulifer and from its plant host, Asclepias curassavica. The flagellates cultivated, all of which belong to the genus Herpetomonas, have been identified chiefly by their biological relationships, which will be described in detail in Part II of this report. The seven strains from latex-feeding insects and latex plants represent two distinct species, which have been designated H. oncopelti and H. lygægorum. The two strains from mosquitoes proved to be the same organism and have been called Herpetomonas culicidarum. The culture obtained from Musca domestica contained larger individuals than those of any other strain, and the organism is morphologically distinct from either of the Calliphora strains. None of the fly flagellates cultivated could be identified with the. species H. muscæ domesticæ or H. calliphoræ, and hence they have been given new names, Herpetomonas muscidarum, H. media, and H. parva. Blood agar plates were used for initial cultivation of the strains from insects and the semisolid leptospira medium for isolation of the plant flagellates. A number of the strains were purified by plating on acid blood agar, a procedure which reduces considerably the growth of bacterial contaminants. The Barber technique was utilized for isolation of the flagellates from flies, because of the very large number of bacteria found with them in these insects, and, in one or two instances, for the purification of impure cultures. Once they have been

  18. COMPARATIVE STUDIES OF HERPETOMONADS AND LEISHMANIAS : I. CULTIVATION OF HERPETOMONADS FROM INSECTS AND PLANTS.

    PubMed

    Noguchi, H; Tilden, E B

    1926-08-31

    Nine strains of herpetomonads have been isolated in pure culture from eight varieties of insects, and three strains from two species of plants. Four of the cultures were derived from latex-feeding insects (Oncopeltus fasciatus, Oncopeltus sp. ?, Lygaeus kalmii) and three from latex plants (Asclepias syriaca, Asclepias nivea), two from mosquitoes (Culex pipiens and Anopheles quadrimaculatus), one from the house fly (Musca domestica), and two from bluebottle flies. In addition impure cultures have been obtained from Oncopeltus cingulifer and from its plant host, Asclepias curassavica. The flagellates cultivated, all of which belong to the genus Herpetomonas, have been identified chiefly by their biological relationships, which will be described in detail in Part II of this report. The seven strains from latex-feeding insects and latex plants represent two distinct species, which have been designated H. oncopelti and H. lygaegorum. The two strains from mosquitoes proved to be the same organism and have been called Herpetomonas culicidarum. The culture obtained from Musca domestica contained larger individuals than those of any other strain, and the organism is morphologically distinct from either of the Calliphora strains. None of the fly flagellates cultivated could be identified with the. species H. muscae domesticae or H. calliphorae, and hence they have been given new names, Herpetomonas muscidarum, H. media, and H. parva. Blood agar plates were used for initial cultivation of the strains from insects and the semisolid leptospira medium for isolation of the plant flagellates. A number of the strains were purified by plating on acid blood agar, a procedure which reduces considerably the growth of bacterial contaminants. The Barber technique was utilized for isolation of the flagellates from flies, because of the very large number of bacteria found with them in these insects, and, in one or two instances, for the purification of impure cultures. Once they have been

  19. Denitrification and chemotaxis of Pseudomonas stutzeri KC in porous media.

    PubMed

    Roush, Caroline J; Lastoskie, Christian M; Worden, R Mark

    2006-01-01

    Chemotaxis is an important mechanism by which microorganisms are dispersed in porous media. A vigorous chemotactic response to concentration gradients formed by microbial consumption of chemoattractants can accelerate transport of bacteria to highly contaminated regions of soils and sediments, enhancing the efficiency of in situ bioremediation operations. Although chemotaxis plays a key role in establishment of biodegradation zones in the subsurface, the effects of physical heterogeneity on bacterial motility are poorly understood. To investigate the influence of porous media heterogeneity on microbial chemotaxis, swarm plate migration experiments were conducted using Pseudomonas stutzeri strain KC, a denitrifying bacterium used for in situ biodegradation of carbon tetrachloride in groundwater. Swarm plate measurements indicate that strain KC is strongly chemotactic toward both acetate and nitrate. A three-component mathematical model was developed to describe the migration of strain KC. Estimates of chemotactic sensitivity were obtained in the homogeneous (agar) phase and in a heterogeneous medium of aquifer solids extracted from the Schoolcraft bioremediation field site in western Michigan. Interestingly, the motility of strain KC is significantly larger in the porous medium than in the aqueous phase. We hypothesize that chemotactic response is enhanced within the heterogeneous medium because chemoattractant gradients formed by nitrate consumption are larger in the confined spaces of the porous medium than in unconfined agar solution. PMID:16760079

  20. Expression of EMAP-II in the rat dental follicle and its potential role in tooth eruption

    PubMed Central

    Liu, Dawen; Wise, Gary E.

    2008-01-01

    Endothelial monocyte-activating polypeptide II (EMAP-II) is an inflammatory cytokine with chemotactic activity. Because the dental follicle (DF) recruits mononuclear cells (osteoclast precursors) to promote the osteoclastogenesis needed for tooth eruption, it was the aim of this study to determine if EMAP-II may contribute to this recruitment. Using a DNA microarray, EMAP-II was found to be highly expressed in vivo in the DFs of day 1 to day 11 postnatal rats, with its expression elevated at days 1 and 3. Using a siRNA to knock down EMAP-II expression also resulted in a reduction in expression of CSF-1 and MCP-1 in the DF cells. Addition of EMAP-II protein to the DF cells partially restored the expression of CSF-1 and MCP-1. In chemotaxis assays using either conditioned medium of the DF cells with anti-EMAP-II antibody added or conditioned medium of DF cells with EMAP-II knocked down by siRNA, migration indexes of bone marrow mononuclear cells were significantly reduced. These results suggest that EMAP-II is another chemotactic molecule in the dental follicle involved in recruitment of mononuclear cells, and that EMAP-II may exert its chemotactic function directly by recruiting mononuclear cells and indirectly by enhancing the expression of other chemotactic molecules (CSF-1 and MCP-1). PMID:18705801

  1. Predicted molecular signaling guiding photoreceptor cell migration following transplantation into damaged retina

    PubMed Central

    Unachukwu, Uchenna John; Warren, Alice; Li, Ze; Mishra, Shawn; Zhou, Jing; Sauane, Moira; Lim, Hyungsik; Vazquez, Maribel; Redenti, Stephen

    2016-01-01

    To replace photoreceptors lost to disease or trauma and restore vision, laboratories around the world are investigating photoreceptor replacement strategies using subretinal transplantation of photoreceptor precursor cells (PPCs) and retinal progenitor cells (RPCs). Significant obstacles to advancement of photoreceptor cell-replacement include low migration rates of transplanted cells into host retina and an absence of data describing chemotactic signaling guiding migration of transplanted cells in the damaged retinal microenvironment. To elucidate chemotactic signaling guiding transplanted cell migration, bioinformatics modeling of PPC transplantation into light-damaged retina was performed. The bioinformatics modeling analyzed whole-genome expression data and matched PPC chemotactic cell-surface receptors to cognate ligands expressed in the light-damaged retinal microenvironment. A library of significantly predicted chemotactic ligand-receptor pairs, as well as downstream signaling networks was generated. PPC and RPC migration in microfluidic ligand gradients were analyzed using a highly predicted ligand-receptor pair, SDF-1α – CXCR4, and both PPCs and RPCs exhibited significant chemotaxis. This work present a systems level model and begins to elucidate molecular mechanisms involved in PPC and RPC migration within the damaged retinal microenvironment. PMID:26935401

  2. Stanniocalcin-1 regulates endothelial gene expression and modulates trans-endothelial migration of leukocytes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mammalian counterpart of the fish calcium-regulating hormone stanniocalcin-1 (STC1) inhibits monocyte chemotactic protein-1- and stromal-derived factor-1alpha (SDF-1alpha)-mediated chemotaxis and diminishes chemokinesis in macrophage-like RAW264.7 and U937 cells in a manner that may involve atte...

  3. Predicted molecular signaling guiding photoreceptor cell migration following transplantation into damaged retina

    NASA Astrophysics Data System (ADS)

    Unachukwu, Uchenna John; Warren, Alice; Li, Ze; Mishra, Shawn; Zhou, Jing; Sauane, Moira; Lim, Hyungsik; Vazquez, Maribel; Redenti, Stephen

    2016-03-01

    To replace photoreceptors lost to disease or trauma and restore vision, laboratories around the world are investigating photoreceptor replacement strategies using subretinal transplantation of photoreceptor precursor cells (PPCs) and retinal progenitor cells (RPCs). Significant obstacles to advancement of photoreceptor cell-replacement include low migration rates of transplanted cells into host retina and an absence of data describing chemotactic signaling guiding migration of transplanted cells in the damaged retinal microenvironment. To elucidate chemotactic signaling guiding transplanted cell migration, bioinformatics modeling of PPC transplantation into light-damaged retina was performed. The bioinformatics modeling analyzed whole-genome expression data and matched PPC chemotactic cell-surface receptors to cognate ligands expressed in the light-damaged retinal microenvironment. A library of significantly predicted chemotactic ligand-receptor pairs, as well as downstream signaling networks was generated. PPC and RPC migration in microfluidic ligand gradients were analyzed using a highly predicted ligand-receptor pair, SDF-1α - CXCR4, and both PPCs and RPCs exhibited significant chemotaxis. This work present a systems level model and begins to elucidate molecular mechanisms involved in PPC and RPC migration within the damaged retinal microenvironment.

  4. Characterization of a chemoattractant for endothelium induced by angiogenesis effectors.

    PubMed

    Raju, K S; Alessandri, G; Gullino, P M

    1984-04-01

    The mechanism of neovascularization was further explored by the use of chemically defined angiogenesis effectors. The vascularization of the rabbit cornea was selected as an experimental approach that permits comparison of one cornea treated by the angiogenesis effector with the contralateral cornea of the same subject treated by the same molecule deprived of angiogenic capacity. Under these conditions, we observed that neovascularization was initiated by the appearance of a chemoattractant for the bovine capillary endothelium only in the cornea treated by the angiogenesis effector. The chemoattractant was purified about 150-fold by a single-step procedure, using gelatin:Sepharose affinity chromatography. Chemoattraction resulted from the combined effect of a chemotactic factor(s) and an activating factor(s). The association of the two enhanced 5- to 8-fold the motility of the capillary endothelium in a concentration-dependent manner with optimum at 0.2 mg/ml. The activating factor(s) does not have chemotactic capacity, but without it, chemotaxis is reduced to about one half. The chemotactic complex was present in the cornea regardless of the nature of the angiogenesis effector used as the triggering device. Heat and proteases eliminated chemotaxis and destroyed the chemotactic complex. Thus, neovascularization may be triggered by effectors able to induce in the cornea proteins, normally not present, that influence angiogenesis via mobilization of capillary endothelium. PMID:6200213

  5. Silent and functional changes in the periplasmic maltose-binding protein of Escherichia coli K12. II. Chemotaxis towards maltose.

    PubMed

    Duplay, P; Szmelcman, S

    1987-04-20

    We examined the chemotactic behavior of ten Escherichia coli mutants able to synthesize a modified periplasmic maltose-binding protein (MBP) retaining high affinity for maltose. Eight were able to grow on maltose (Mal+), two were not (Mal-). In the capillary assay six out of eight of the Mal+ strains showed an optimal response at the same concentration of maltose as the wild-type strain; the amplitude of the response was strongly reduced in two Mal+ mutants and partially affected in one. The amplitude of the chemotactic response of the two Mal- strains was at least equal to that of the wild type, so that the chemotactic and transport functions of MBP were dissociated in these two cases. We define two regions of the protein (residues 297 to 303 and 364 to 369), that are important both for the chemotactic response and for transport, and one region (residues 207 to 220) that is essential for transport but dispensable for chemotaxis. Interestingly, some regions that were found to be inessential for transport are also dispensable for chemotaxis. PMID:3309329

  6. Chemotaxis of bio-hybrid multiple bacteria-driven microswimmers

    PubMed Central

    Zhuang, Jiang; Sitti, Metin

    2016-01-01

    In this study, in a bio-hybrid microswimmer system driven by multiple Serratia marcescens bacteria, we quantify the chemotactic drift of a large number of microswimmers towards L-serine and elucidate the associated collective chemotaxis behavior by statistical analysis of over a thousand swimming trajectories of the microswimmers. The results show that the microswimmers have a strong heading preference for moving up the L-serine gradient, while their speed does not change considerably when moving up and down the gradient; therefore, the heading bias constitutes the major factor that produces the chemotactic drift. The heading direction of a microswimmer is found to be significantly more persistent when it moves up the L-serine gradient than when it travels down the gradient; this effect causes the apparent heading preference of the microswimmers and is the crucial reason that enables the seemingly cooperative chemotaxis of multiple bacteria on a microswimmer. In addition, we find that their chemotactic drift velocity increases superquadratically with their mean swimming speed, suggesting that chemotaxis of bio-hybrid microsystems can be enhanced by designing and building faster microswimmers. Such bio-hybrid microswimmers with chemotactic steering capability may find future applications in targeted drug delivery, bioengineering, and lab-on-a-chip devices. PMID:27555465

  7. Towards a continuum theory of movement in interacting cellular systems

    NASA Astrophysics Data System (ADS)

    Newman, Timothy

    2003-10-01

    Interacting cellular systems form the basis of all higher organisms, and are fundamental to the understanding of embryogenesis, organ function, and neoplasms. I will describe a stochastic model of cell interactions which can be applied to these problems, and present some of our recent results on chemotactic response.

  8. 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.

  9. 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.

  10. External and internal constraints on eukaryotic chemotaxis.

    PubMed

    Fuller, Danny; Chen, Wen; Adler, Micha; Groisman, Alex; Levine, Herbert; Rappel, Wouter-Jan; Loomis, William F

    2010-05-25

    Chemotaxis, the chemically guided movement of cells, plays an important role in several biological processes including cancer, wound healing, and embryogenesis. Chemotacting cells are able to sense shallow chemical gradients where the concentration of chemoattractant differs by only a few percent from one side of the cell to the other, over a wide range of local concentrations. Exactly what limits the chemotactic ability of these cells is presently unclear. Here we determine the chemotactic response of Dictyostelium cells to exponential gradients of varying steepness and local concentration of the chemoattractant cAMP. We find that the cells are sensitive to the steepness of the gradient as well as to the local concentration. Using information theory techniques, we derive a formula for the mutual information between the input gradient and the spatial distribution of bound receptors and also compute the mutual information between the input gradient and the motility direction in the experiments. A comparison between these quantities reveals that for shallow gradients, in which the concentration difference between the back and the front of a 10-mum-diameter cell is <5%, and for small local concentrations (<10 nM) the intracellular information loss is insignificant. Thus, external fluctuations due to the finite number of receptors dominate and limit the chemotactic response. For steeper gradients and higher local concentrations, the intracellular information processing is suboptimal and results in a smaller mutual information between the input gradient and the motility direction than would have been predicted from the ligand-receptor binding process. PMID:20457897

  11. Unleashing mesenchymal chemotaxis.

    PubMed

    Aguilar-Cuenca, Rocío; Vicente-Manzanares, Miguel

    2014-12-22

    In this issue of Developmental Cell, Asokan and colleagues (2014) report that the phospholipase Cγ (PLCγ)-diacyl glycerol (DAG) protein kinase Cα (PKCα) signaling axis inhibits actomyosin bundling. This preferentially occurs at the leading edge of chemotactic mesenchymal cells via noncanonical phosphorylation of the regulatory light chain (RLC) of nonmuscle myosin II. PMID:25535912

  12. CONSTITUTIVE AND STIMULATED MCP-1, GROA, B, AND Y EXPRESSION IN HUMAN A AIRWAY EPITHELIUM AND BRONCHOALVEOLAR MACROPHAGES

    EPA Science Inventory

    Constitutive expression of mRNAs for GROa, GROB, GROY, and MCP-1, belonging to the chemokine family of 8-10 kD cytokines with chemotactic properties for granulocytes and monocytes, has been identified in freshly isolated human nasal and bronchial epithelium, and in bronchoalveola...

  13. Localized bacterial infection in a distributed model for tissue inflammation.

    PubMed

    Lauffenburger, D A; Kennedy, C R

    1983-01-01

    Phagocyte motility and chemotaxis are included in a distributed mathematical model for the inflammatory response to bacterial invasion of tissue. Both uniform and non-uniform steady state solutions may occur for the model equations governing bacteria and phagocyte densities in a macroscopic tissue region. The non-uniform states appear to be more dangerous because they allow large bacteria densities concentrated in local foci, and in some cases greater total bacteria and phagocyte populations. Using a linear stability analysis, it is shown that a phagocyte chemotactic response smaller than a critical value can lead to a non-uniform state, while a chemotactic response greater than this critical value stabilizes the uniform state. This result is the opposite of that found for the role of chemotaxis in aggregation of slimemold amoebae because, in the inflammatory response, the chemotactic population serves as an inhibitor rather than an activator. We speculate that these non-uniform steady states could be related to the localized cell aggregation seen in chronic granulomatous inflammation. The formation of non-uniform states is not necessarily a consequence of defective phagocyte chemotaxis, however. Rather, certain values of the kinetic parameters can yield values for the critical chemotactic response which are greater than the normal response. Numerical computations of the transient inflammatory response to bacterial challenge are presented, using parameter values estimated from the experimental literature wherever possible. PMID:6827185

  14. Molecular cloning of porcine chemokine CXC motif ligand 2 (CXCL2) and mapping to the SSC8

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maternal recognition of pregnancy is accompanied by inflammatory responses with leukocytosis and increased levels of cytokines and chemokines. Human trophoblast cells secrete chemokine CXC motif ligand 1 (CXCL1)/Gro-a and other chemotactic proteins, while monocytes co-cultured with trophoblast cells...

  15. Amygdalin blocks the in vitro adhesion and invasion of renal cell carcinoma cells by an integrin-dependent mechanism.

    PubMed

    Juengel, Eva; Afschar, Masud; Makarević, Jasmina; Rutz, Jochen; Tsaur, Igor; Mani, Jens; Nelson, Karen; Haferkamp, Axel; Blaheta, Roman A

    2016-03-01

    Information about the natural compound amygdalin, which is employed as an antitumor agent, is sparse and thus its efficacy remains controversial. In this study, to determine whether amygdalin exerts antitumor effects on renal cell carcinoma (RCC) cells, its impact on RCC metastatic activity was investigated. The RCC cell lines, Caki-1, KTC-26 and A498, were exposed to amygdalin from apricot kernels, and adhesion to human vascular endothelium, immobilized collagen or fibronectin was investigated. The influence of amygdalin on chemotactic and invasive activity was also determined, as was the influence of amygdalin on surface and total cellular α and β integrin expression, which are involved in metastasis. We noted that amygdalin caused significant reductions in chemotactic activity, invasion and adhesion to endothelium, collagen and fibronectin. Using FACScan analysis, we noted that amygdalin also induced reductions, particularly in integrins α5 and α6, in all three cell lines. Functional blocking of α5 resulted in significantly diminished adhesion of KTC-26 and A498 to collagen and also in decreased chemotactic behavior in all three cell lines. Blocking α6 integrin significantly reduced chemotactic activity in all three cell lines. Thus, we suggest that exposing RCC cells to amygdalin inhibits metastatic spread and is associated with downregulation of α5 and α6 integrins. Therefore, we posit that amygdalin exerts antitumor activity in vitro, and this may be linked to integrin regulation. PMID:26781971

  16. Predicted molecular signaling guiding photoreceptor cell migration following transplantation into damaged retina.

    PubMed

    Unachukwu, Uchenna John; Warren, Alice; Li, Ze; Mishra, Shawn; Zhou, Jing; Sauane, Moira; Lim, Hyungsik; Vazquez, Maribel; Redenti, Stephen

    2016-01-01

    To replace photoreceptors lost to disease or trauma and restore vision, laboratories around the world are investigating photoreceptor replacement strategies using subretinal transplantation of photoreceptor precursor cells (PPCs) and retinal progenitor cells (RPCs). Significant obstacles to advancement of photoreceptor cell-replacement include low migration rates of transplanted cells into host retina and an absence of data describing chemotactic signaling guiding migration of transplanted cells in the damaged retinal microenvironment. To elucidate chemotactic signaling guiding transplanted cell migration, bioinformatics modeling of PPC transplantation into light-damaged retina was performed. The bioinformatics modeling analyzed whole-genome expression data and matched PPC chemotactic cell-surface receptors to cognate ligands expressed in the light-damaged retinal microenvironment. A library of significantly predicted chemotactic ligand-receptor pairs, as well as downstream signaling networks was generated. PPC and RPC migration in microfluidic ligand gradients were analyzed using a highly predicted ligand-receptor pair, SDF-1α - CXCR4, and both PPCs and RPCs exhibited significant chemotaxis. This work present a systems level model and begins to elucidate molecular mechanisms involved in PPC and RPC migration within the damaged retinal microenvironment. PMID:26935401

  17. Chemotaxis of Pseudomonas putida toward chlorinated benzoates

    SciTech Connect

    Harwood, C.S.; Parales, R.E.; Dispensa, M. )

    1990-05-01

    The chlorinated aromatic acids 3-chlorobenzoate and 4-chlorobenzoate are chemoattractants for Pseudomonas putida PRS2000. These compounds are detected by a chromosomally encoded chemotactic response to benzoate which is inducible by {beta}-ketoadipate, and intermediate of benzoate catabolism. Plasmid pAC27, encoding enzymes for 3-chlorobenzoate degradation, does not appear to carry genes for chemotaxis toward chlorinated compounds.

  18. Coupled effect of chemotaxis and growth on microbial distributions in organic-amended aquifer sediments: Observations from laboratory and field studies

    USGS Publications Warehouse

    Wang, M.; Ford, R.M.; Harvey, R.W.

    2008-01-01

    The inter-relationship of growth and chemotactic response exhibited by two common soil-inhabiting bacteria was investigated to determine its impact on bacterial migration. Filter-chambers were used to simulate aquifer sediments characterized by vertical gradients of organic contaminants in both artificial groundwater flow systems in the laboratory and within the screened intervals of observation wells in a sandy aquifer. A labile model contaminant (acetate) was added to the top compartments of the three-part chambers, whereas bacteria with a demonstrated propensity to grow on and chemotactically respond to acetate were introduced to the lower compartments, The motility and chemotactic response of Pseudomonas putida F1 resulted in 40 to 110% greater abundances in the upper compartments and concomitant 22 to 70% depletions in the lower compartments relative to the nonchemotactic controls over 2 days. Bacteria were in greatest abundance within the sand plug that separated the upper and lower compartments where sharp acetate gradients induced a strong chemotactic response. This observation was consistent with predictions from a mathematical model. In agreement with the laboratory results, the down-well filter-chamber incubations with Pseudomonas stutzeri in the aquifer indicated that 91% fewer bacteria resided in the lower compartment than the control experiment without acetate at 15 h. The combination of chemotaxis and growth greatly accelerated the migration of bacteria toward and subsequent abundance at the higher acetate concentration. ?? 2008 American Chemical Society.

  19. Chemotaxis of bio-hybrid multiple bacteria-driven microswimmers.

    PubMed

    Zhuang, Jiang; Sitti, Metin

    2016-01-01

    In this study, in a bio-hybrid microswimmer system driven by multiple Serratia marcescens bacteria, we quantify the chemotactic drift of a large number of microswimmers towards L-serine and elucidate the associated collective chemotaxis behavior by statistical analysis of over a thousand swimming trajectories of the microswimmers. The results show that the microswimmers have a strong heading preference for moving up the L-serine gradient, while their speed does not change considerably when moving up and down the gradient; therefore, the heading bias constitutes the major factor that produces the chemotactic drift. The heading direction of a microswimmer is found to be significantly more persistent when it moves up the L-serine gradient than when it travels down the gradient; this effect causes the apparent heading preference of the microswimmers and is the crucial reason that enables the seemingly cooperative chemotaxis of multiple bacteria on a microswimmer. In addition, we find that their chemotactic drift velocity increases superquadratically with their mean swimming speed, suggesting that chemotaxis of bio-hybrid microsystems can be enhanced by designing and building faster microswimmers. Such bio-hybrid microswimmers with chemotactic steering capability may find future applications in targeted drug delivery, bioengineering, and lab-on-a-chip devices. PMID:27555465

  20. Migration of canine neutrophils to chitin and chitosan.

    PubMed

    Usami, Y; Okamoto, Y; Minami, S; Matsuhashi, A; Kumazawa, N H; Tanioka, S; Shigemasa, Y

    1994-12-01

    Suspension of chitin and chitosan particles (mean size of 1 micron) were found to attract canine neutrophils chemotactically as determined by a checkerboard assay through polycarbonate filter with 5 microns pore size in Blind well chamber. Suspension of chitin induced chemokinetic migrations of the neutrophils. These evidences might reflect accumulation of neutrophils to chitin- and chitosan-implanted regions in dogs. PMID:7696425

  1. Biochemical and molecular characterization of the novobiocin and rifampicin resistant Aeromonas hydrophila vaccine strain AL09-71 N+R compared to its virulent parent strain AL90-71

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To understand the fitness cost of novobiocin- and rifampicin- resistance in an attenuated Aeromonas hydrophiila vaccine strain AL09-71 N+R compared to its virulent parent strain AL09-71, colony size, cell size, cell proliferation rate, chemotactic response, and the ability to invade catfish gill cel...

  2. Gonadal Maturation Changes Chemotaxis Behavior and Neural Processing in the Olfactory Circuit of Caenorhabditis elegans.

    PubMed

    Fujiwara, Manabi; Aoyama, Itaru; Hino, Takahiro; Teramoto, Takayuki; Ishihara, Takeshi

    2016-06-20

    Many animal species change their behavior according to their stage of development. However, the mechanisms involved in translating their developmental stage into the modifications of the neuronal circuits that underlie these behavioral changes remain unknown. Here we show that Caenorhabditis elegans changes its olfactory preferences during development. Larvae exhibit a weak chemotactic response to the food-associated odor diacetyl, whereas adults exhibit a strong response. We show that germline loss, caused either by laser ablation of germline precursor cells or mutations, results in a diacetyl-specific chemotactic defect in adult animals. These results suggest that germline cells, which proliferate dramatically during the larval stages, enhance chemotaxis to diacetyl. Removal experiments of specific neurons suggested that AWA olfactory neurons and their downstream interneurons, AIA and AIB, are required for germline-dependent chemotactic enhancement. Calcium imaging in animals lacking germline cells indicates that the neural responses of AWA and AIB to diacetyl stimuli are decreased compared with animals with an intact germline. These changes in neural activities may at least partly explain the behavioral change of animals lacking germline cells. Furthermore, this germline-dependent chemotactic change depends on the transcription factor DAF-16/FOXO. We find that organismal behavior changes throughout development by integrating information about physiological status from internal tissues to modify a simple sensory circuit. PMID:27265391

  3. Proteomic identification of in vivo substrates for matrix metalloproteinases 2 and 9 reveals a mechanism for resolution of inflammation.

    PubMed

    Greenlee, Kendra J; Corry, David B; Engler, David A; Matsunami, Risë K; Tessier, Philippe; Cook, Richard G; Werb, Zena; Kheradmand, Farrah

    2006-11-15

    Clearance of allergic inflammatory cells from the lung through matrix metalloproteinases (MMPs) is necessary to prevent lethal asphyxiation, but mechanistic insight into this essential homeostatic process is lacking. In this study, we have used a proteomics approach to determine how MMPs promote egression of lung inflammatory cells through the airway. MMP2- and MMP9-dependent cleavage of individual Th2 chemokines modulated their chemotactic activity; however, the net effect of complementing bronchoalveolar lavage fluid of allergen-challenged MMP2(-/-)/MMP9(-/-) mice with active MMP2 and MMP9 was to markedly enhance its overall chemotactic activity. In the bronchoalveolar fluid of MMP2(-/-)/MMP9(-/-) allergic mice, we identified several chemotactic molecules that possessed putative MMP2 and MMP9 cleavage sites and were present as higher molecular mass species. In vitro cleavage assays and mass spectroscopy confirmed that three of the identified proteins, Ym1, S100A8, and S100A9, were substrates of MMP2, MMP9, or both. Function-blocking Abs to S100 proteins significantly altered allergic inflammatory cell migration into the alveolar space. Thus, an important effect of MMPs is to differentially modify chemotactic bioactivity through proteolytic processing of proteins present in the airway. These findings provide a molecular mechanism to explain the enhanced clearance of lung inflammatory cells through the airway and reveal a novel approach to target new therapies for asthma. PMID:17082650

  4. Basal polarization of the mucosal compartment in Flavobacterium columnare susceptible and resistant channel catfish Ictalurus punctatus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The freshwater bacterial pathogen, Flavobacterium columnare, infects a variety of ornamental and farmed fish species worldwide through mucosal attachment points on the gill and skin. While previous studies have demonstrated a chemotactic response of F. columnare to fish mucus, little is known about ...

  5. N-3 and n-6 polyunsaturated fatty acids differentially regulate adipose angiotensinogen and other inflammatory adipokines in part via NF-kB dependent mechanisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessive secretion of angiotensinogen (Agt) and other adipokines such as Interleukin-6 (IL-6) and Monocyte chemotactic protein-1 (MCP-1) have been linked to obesity and associated metabolic disorders, with a common feature being inflammation. We have previously shown that n-3 polyunsaturated fatty ...

  6. Single-cell Migration Chip for Chemotaxis-based Microfluidic Selection of Heterogeneous Cell Populations

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Chih; Allen, Steven G.; Ingram, Patrick N.; Buckanovich, Ronald; Merajver, Sofia D.; Yoon, Euisik

    2015-05-01

    Tumor cell migration toward and intravasation into capillaries is an early and key event in cancer metastasis, yet not all cancer cells are imbued with the same capability to do so. This heterogeneity within a tumor is a fundamental property of cancer. Tools to help us understand what molecular characteristics allow a certain subpopulation of cells to spread from the primary tumor are thus critical for overcoming metastasis. Conventional in vitro migration platforms treat populations in aggregate, which leads to a masking of intrinsic differences among cells. Some migration assays reported recently have single-cell resolution, but these platforms do not provide for selective retrieval of the distinct migrating and non-migrating cell populations for further analysis. Thus, to study the intrinsic differences in cells responsible for chemotactic heterogeneity, we developed a single-cell migration platform so that individual cells’ migration behavior can be studied and the heterogeneous population sorted based upon chemotactic phenotype. Furthermore, after migration, the highly chemotactic and non-chemotactic cells were retrieved and proved viable for later molecular analysis of their differences. Moreover, we modified the migration channel to resemble lymphatic capillaries to better understand how certain cancer cells are able to move through geometrically confining spaces.

  7. Detection of sialoglycomolecules in five plant trypanosomatids and in an insect phytophagous isolate.

    PubMed

    Souza dos Santos, André Luis; Sales Alviano, Celuta; de Araújo Soares, Rosangela Maria

    2002-08-27

    The sialoglycoprotein profiles of five plant trypanosomatids (Phytomonas spp.) and of one flagellate (Herpetomonas sp.) isolated from the salivary gland of a phytophagous insect (Phthia picta) were analyzed by Western blotting using three distinct lectins (LFA, SNA and MAA), which recognize specifically sialic acid residues in glycoconjugates. All six flagellates presented at least one polypeptide recognized by the lectins, with the exception of Phytomonas françai, which did not show any reactivity with SNA agglutinin. Phytomonas serpens and P. françai showed the most distinct pattern of sialoglycoproteins. Phytomonas mcgheei, Herpetomonas sp. and the two other Phytomonas spp., isolated from latex, displayed an identical sialomolecule profile. We discuss the possible role of the sialoglycoproteins in the physiology of these trypanosomatids. PMID:12204367

  8. Treatment of industrial effluents by a continuous system: electrocoagulation--activated sludge.

    PubMed

    Moisés, Tejocote-Pérez; Patricia, Balderas-Hernández; Barrera-Díaz, C E; Gabriela, Roa-Morales; Natividad-Rangel, Reyna

    2010-10-01

    A continuous system electrocoagulation--active sludge was designed and built for the treatment of industrial wastewater. The system included an electrochemical reactor with aluminum electrodes, a clarifier and a biological reactor. The electrochemical reactor was tested under different flowrates (50, 100 and 200 mL/min). In the biological reactor, the performance of different cultures of active sludge was assessed: coliform bacterial, ciliate and flagellate protozoa and aquatic fungus. Overall treatment efficiencies of color, turbidity and COD removal were 94%, 92% and 80%, respectively, under optimal conditions of 50 mL/min flowrate and using ciliate and flagellate protozoa. It was concluded that the system was efficient for the treatment of industrial wastewater. PMID:20570506

  9. 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

  10. Life-cycle modification in open oceans accounts for genome variability in a cosmopolitan phytoplankton.

    PubMed

    von Dassow, Peter; John, Uwe; Ogata, Hiroyuki; Probert, Ian; Bendif, El Mahdi; Kegel, Jessica U; Audic, Stéphane; Wincker, Patrick; Da Silva, Corinne; Claverie, Jean-Michel; Doney, Scott; Glover, David M; Flores, Daniella Mella; Herrera, Yeritza; Lescot, Magali; Garet-Delmas, Marie-José; de Vargas, Colomban

    2015-06-01

    Emiliania huxleyi is the most abundant calcifying plankton in modern oceans with substantial intraspecific genome variability and a biphasic life cycle involving sexual alternation between calcified 2N and flagellated 1N cells. We show that high genome content variability in Emiliania relates to erosion of 1N-specific genes and loss of the ability to form flagellated cells. Analysis of 185 E. huxleyi strains isolated from world oceans suggests that loss of flagella occurred independently in lineages inhabiting oligotrophic open oceans over short evolutionary timescales. This environmentally linked physiogenomic change suggests life cycling is not advantageous in very large/diluted populations experiencing low biotic pressure and low ecological variability. Gene loss did not appear to reflect pressure for genome streamlining in oligotrophic oceans as previously observed in picoplankton. Life-cycle modifications might be common in plankton and cause major functional variability to be hidden from traditional taxonomic or molecular markers. PMID:25461969

  11. Life-cycle modification in open oceans accounts for genome variability in a cosmopolitan phytoplankton

    PubMed Central

    von Dassow, Peter; John, Uwe; Ogata, Hiroyuki; Probert, Ian; Bendif, El Mahdi; Kegel, Jessica U; Audic, Stéphane; Wincker, Patrick; Da Silva, Corinne; Claverie, Jean-Michel; Doney, Scott; Glover, David M; Flores, Daniella Mella; Herrera, Yeritza; Lescot, Magali; Garet-Delmas, Marie-José; de Vargas, Colomban

    2015-01-01

    Emiliania huxleyi is the most abundant calcifying plankton in modern oceans with substantial intraspecific genome variability and a biphasic life cycle involving sexual alternation between calcified 2N and flagellated 1N cells. We show that high genome content variability in Emiliania relates to erosion of 1N-specific genes and loss of the ability to form flagellated cells. Analysis of 185 E. huxleyi strains isolated from world oceans suggests that loss of flagella occurred independently in lineages inhabiting oligotrophic open oceans over short evolutionary timescales. This environmentally linked physiogenomic change suggests life cycling is not advantageous in very large/diluted populations experiencing low biotic pressure and low ecological variability. Gene loss did not appear to reflect pressure for genome streamlining in oligotrophic oceans as previously observed in picoplankton. Life-cycle modifications might be common in plankton and cause major functional variability to be hidden from traditional taxonomic or molecular markers. PMID:25461969

  12. Graviperception and gravitaxis in algae

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.; Lebert, M.

    Photosynthetic flagellates are among the most intensely studied unicellular organisms in the field of graviperception and gravitaxis. While the phenomenon of graviorientation has been known for many decades, only recently was the molecular mechanism unveiled. Earlier hypotheses tried to explain the precise orientation by a passive buoy mechanism assuming the tail end to be heavier than the front. In the photosynthetic flagellate Euglena gracilis, the whole cell body is denser than the surrounding medium, pressing onto the lower cell membrane where it seems to activate mechanosensitive ion channels specific for calcium. The calcium entering the cells during reorientation can be visualized by the fluorescence probe, Calcium Crimson. Cyclic AMP is likewise involved in the molecular pathway. Inhibitors of calcium channels and ionophores impair gravitaxis while caffeine, a blocker of the phosphodiesterase, enhances the precision of orientation.

  13. Quantitative analysis of the chemotaxis of a green alga, Chlamydomonas reinhardtii, to bicarbonate using diffusion-based microfluidic device.

    PubMed

    Choi, Hong Il; Kim, Jaoon Young Hwan; Kwak, Ho Seok; Sung, Young Joon; Sim, Sang Jun

    2016-01-01

    There is a growing interest in the photosynthetic carbon fixation by microalgae for the production of valuable products from carbon dioxide (CO2). Microalgae are capable of transporting bicarbonate (HCO3 (-)), the most abundant form of inorganic carbon species in the water, as a source of CO2 for photosynthesis. Despite the importance of HCO3 (-) as the carbon source, little is known about the chemotactic response of microalgae to HCO3 (-). Here, we showed the chemotaxis of a model alga, Chlamydomonas reinhardtii, towards HCO3 (-) using an agarose gel-based microfluidic device with a flow-free and stable chemical gradient during the entire assay period. The device was validated by analyzing the chemotactic responses of C. reinhardtii to the previously known chemoattractants (NH4Cl and CoCl2) and chemotactically neutral molecule (NaCl). We found that C. reinhardtii exhibited the strongest chemotactic response to bicarbonate at the concentration of 26 mM in a microfluidic device. The chemotactic response to bicarbonate showed a circadian rhythm with a peak during the dark period and a valley during the light period. We also observed the changes in the chemotaxis to bicarbonate by an inhibitor of bicarbonate transporters and a mutation in CIA5, a transcriptional regulator of carbon concentrating mechanism, indicating the relationship between chemotaxis to bicarbonate and inorganic carbon metabolism in C. reinhardtii. To the best of our knowledge, this is the first report of the chemotaxis of C. reinhardtii towards HCO3 (-), which contributes to the understanding of the physiological role of the chemotaxis to bicarbonate and its relevance to inorganic carbon utilization. PMID:26958101

  14. Challenges and perspectives of Chagas disease: a review

    PubMed Central

    2013-01-01

    Chagas disease (CD), also known as American trypanosomiasis, is caused by the flagellated protozoan Trypanosoma cruzi, and affects an estimated 8 to 10 million people worldwide. In Latin America, 25 million people live in risk areas, while in 2008 alone, 10,000 CD-related deaths were reported. This review aimed to evaluate the challenges of CD control, future perspectives, and actions performed worldwide to control expansion of the disease and its impact on public health in Latin America. PMID:24354455

  15. Herpetomonas ztiplika n. sp. (Kinetoplastida: Trypanosomatidae): a parasite of the blood-sucking biting midge Culicoides kibunensis Tokunaga, 1937 (Diptera: Ceratopogonidae).

    PubMed

    Podlipaev, Sergei; Votýpka, Jan; Jirků, Milan; Svobodová, Milena; Lukes, Julius

    2004-04-01

    Herein, we describe the first case of a natural infection of biting midges by a kinetoplastid protozoan. Flagellates from a female Culicoides kibunensis captured in a bird's nest were introduced into culture and characterized by light and electron microscopy. However, because the morphological data were inconclusive, the novel endosymbiont-free trypanosomatid was assigned into Herpetomonas primarily on the basis of the 18S and 5S ribosomal RNA (rRNA) gene sequences. PMID:15165057

  16. Isolation of the trichomonad Tetratrichomonas buttreyi (Hibler et al., 1960) Honigberg, 1963 in bovine diarrhoeic faeces.

    PubMed

    Castella, J; Muńoz, E; Ferrer, D; Gutiérrez, J F

    1997-06-01

    A trichomonad was found in the faeces of a heifer with watery diarrhoea. It was classified as Tetratrichomonas buttreyi according to its morphology as revealed by scanning electron microscopy. This flagellate was successfully maintained in a cysteine-peptone-liver medium. It is, to our knowledge, the first report of Tetratrichomonas buttreyi in Spain. This trichomonad appears to be a nonpathogenic commensal which often proliferates in fluid faeces. PMID:9195708

  17. Tolerance of sewage treatment plant microorganisms to mosquitocides.

    PubMed

    Tietze, N S; Olson, M A; Hester, P G; Moore, J J

    1993-12-01

    Beneficial protozoa and rotifers collected from a wastewater treatment plant in Panama City, FL, were tested for tolerance to 11 commonly used mosquito larvicides and adulticides in the laboratory. The acute effects were assessed using selected concentrations of the adulticides fenthion, malathion, naled, permethrin, and resmethrin; and the larvicides Bacillus thuringiensis israelensis, Bacillus sphaericus, diflubenzuron, larviciding oil, methoprene, and temephos for the following microorganism taxa: ameoboids, flagellates, free-swimming ciliates, stalked ciliates, and rotifers. PMID:8126488

  18. Molecular identification of trypanosomatids in wild animals.

    PubMed

    Tenório, M S; Oliveira e Sousa, L; Alves-Martin, M F; Paixão, M S; Rodrigues, M V; Starke-Buzetti, W A; Araújo Junior, J P; Lucheis, S B

    2014-06-16

    Diverse wild animal species can be reservoirs of zoonotic flagellate parasites, which can cause pathologic Chagas disease. The present study aimed to detect the natural occurrence of flagellate parasites through direct microscopic examination of the parasites in blood samples and through PCR of whole blood and blood culture (haemoculture) samples from 38 captive and 65 free-living wild animals in the Centre for Conservation of Wild Fauna (CCWF), an area endemic for leishmaniasis. For this study, PCR was accomplished using primers for the ribosomal region (ITS-1) of the flagellate parasites. The amplified fragments were cloned and sequenced to identify DNA of the Trypanosomatid parasite species, observed in blood cultures from 3.9% (04/103) of the animals. Through these techniques, Trypanosoma cruzi was identified in haemoculture samples of the following three free-living species: common agouti (Dasyprocta aguti), white-eared opossum (Didelphis albiventris), and nine-banded armadillo (Dasypus novemcinctus). Furthermore, Trypanosoma minasense was identified in whole blood samples from 01 (0.9%) captive animal (black howler monkey-Alouatta caraya). These results demonstrated the first report of T. cruzi isolation in wild species from the CCWF using blood culture, which can be applied in addition to molecular tools for epidemiological studies and to identify trypanosomatids in wild animals. PMID:24636787

  19. Response of the protistan community of a rice field soil to different oxygen tensions.

    PubMed

    Takenouchi, Yuriko; Iwasaki, Kazufumi; Murase, Jun

    2016-07-01

    Heterotrophic protists in soil are grazers that control the biomass and community structure of bacteria, thereby enhancing nutrient recycling. Oxygen regulates the microeukaryotic community, but little is known about its response to microoxic conditions. Here we studied the impact of oxygen tension on culturable heterotrophic protists in a rice field soil. The number of protists, dominated by amoeba and flagellates, under oxygen tensions ranging from atmospheric level (21%) to below the Pasteur point (0.08%) were similar (10(4) cells g(-1) dry soil); no protists were detected under anoxic conditions. DGGE fingerprinting of microeukaryotes demonstrated a shift in the community structure depending on the oxygen tension during growth. Both common and specific amoeba and flagellates were identified at different oxygen tensions. Amoeba isolates (Acanthamoeba sp. and Hartmannella sp.) grew to the same extent under the oxygen tensions tested; the Acanthamoeba sp. isolate migrated more slowly under the lowest tension (0.08%). Our results demonstrated that amoeba and flagellates in soil adapt to a wide range of oxygen tensions with a shift in community structure. This suggests an ability to search for food in soil environments such as the oxic-anoxic interface of flooded soil or inside soil aggregates that are inaccessible to ciliates. PMID:27183973

  20. Temporal patterns of protozooplankton abundance in the Clyde and Loch Striven

    NASA Astrophysics Data System (ADS)

    Laybourn-Parry, Johanna; Rogerson, Andrew; Crawford, David W.

    1992-11-01

    The ciliate and flagellate protozooplankton of the Clyde Estuary and Loch Striven were investigated over a 12 month period in 1990. There were distinct differences in the patterns of occurrence and numbers of the Protozoa in the two brackish locations, attributable to different physical and chemical conditions. Phototrophic flagellate numbers were higher in Loch Striven, where overall chlorophyll a concentrations were also higher. In contrast heterotrophic flagellate densities were higher in the Clyde and were abundant throughout the year, while in Loch Striven they showed a distinct seasonal pattern with peak numbers occurring in the summer. Heterotrophic dinoflagellates were periodically very abundant, particularly in Loch Striven and the lower Clyde. The ciliate communities showed marked differences in species composition and higher numbers occurred in the Clyde compared to Loch Striven. Tintinnid ciliates formed a regular component of the community in Loch Striven, but were less common in the Clyde. However, aloricate ciliates, particularly oligotrichs and very small bactivorous ciliates (< 20 μm) dominated the ciliate assemblage. Apart from Laboea very few of the oligotrichs contained plastids, and were therefore not practising mixotrophy. In both systems the microbial plankton is largely dependent on allochthonous carbon. High turbidity, particularly in the Clyde resulted in low concentrations of chlorophyll a and a low incidence of mixotrophy among ciliates.

  1. Adaptation of phytoplankton communities to mesoscale eddies in the Mozambique Channel

    NASA Astrophysics Data System (ADS)

    Barlow, R.; Lamont, T.; Morris, T.; Sessions, H.; van den Berg, M.

    2014-02-01

    An investigation of phytoplankton pigment and absorption characteristics was undertaken during three research cruises in the Mozambique Channel to elucidate community structure and examine the adaptation of populations to mesoscale features at the surface and the deep chlorophyll maximum (DCM). Total chlorophyll a concentration (TChla) at the surface was determined to be greater in cyclonic eddies than in anticyclones, while TChla in divergence and shelf zones were similar to cyclones, with frontal zones being slightly lower. TChla at the DCM was similar for all categories, although there was a tendency for anticyclones to have lower TChla. Prokaryotes were the most significant phytoplankton group at the surface, with small flagellates also being of secondary importance, while flagellates dominated at the DCM. A few shelf stations, and frontal and shelf stations close to the shelf, displayed high TChla and diatom domination, particularly at the DCM. Absorption properties and photopigment indices revealed that prokaryote dominated communities had high chlorophyll-specific absorption coefficients, a large range in the proportion of TChla within the total pigment pool and a high proportion of photoprotective carotenoids. Diatoms had low chlorophyll-specific absorption, a relatively high proportion of TChla, and elevated proportions of photosynthetic carotenoids and chlorophyll c. Flagellate dominated communities had intermediate chlorophyll-specific absorption, a lower proportion of TChla, elevated photosynthetic carotenoids and intermediate chlorophyll c.

  2. Use of genetically marked minicells as a probe in measurement of predation on bacteria in aquatic environments. [Ochromonas sp. ; Escherichia coli

    SciTech Connect

    Wikner, J.; Andersson, A.; Normark, S.; Hagstroem, A.

    1986-07-01

    Minicells produced by Escherichia coli M2141 were used as probes to measure predation on pelagic bacteria in situ. The minicells, labeled with (/sup 35/S)methionine in one specific protein, were shown to disappear in the presence of a microflagellate (Ochromonas sp.), as seen by a decrease in the amount of labeled marker protein with time. Incubation in filtered (pore size, 0.2 ..mu..m) and autoclaved seawater did not affect the amount of labeled marker protein in the minicell. The generation time of flagellates feeding on minicells was determined to be similar to that found for flagellates grown on seawater bacteria or living E. coli NC3. Data indicate that minicells are seen as true food particles by the flagellates. The minicell probe was used in recapture experiments, in which predation in situ on pelagic bacteria was demonstrated. The rate of bacterial production showed a clear covariation with the rate of predation, both in different sea areas and in depth profiles. The obtained results (11 field experiments) showed that the rate of predation, on average, accounts for the consumption of 62% of the bacteria produced.

  3. Use of proteolytic enzymes as an additional tool for trypanosomatid identification.

    PubMed

    Santos, A L S; Abreu, C M; Alviano, C S; Soares, R M A

    2005-01-01

    The expression of proteolytic activities in the Trypanosomatidae family was explored as a potential marker to discriminate between the morphologically indistinguishable flagellates isolated from insects and plants. We have comparatively analysed the proteolytic profiles of 19 monoxenous trypanosomatids (Herpetomonas anglusteri, H. samuelpessoai, H. mariadeanei, H. roitmani, H. muscarum ingenoplastis, H. muscarum muscarum, H. megaseliae, H. dendoderi, Herpetomoas sp., Crithidia oncopelti, C. deanei, C. acanthocephali, C. harmosa, C. fasciculata, C. guilhermei, C. luciliae, Blastocrithidia culicis, Leptomonas samueli and Lept. seymouri) and 4 heteroxenous flagellates (Phytomonas serpens, P. mcgheei, Trypanosoma cruzi and Leishmania amazonensis) by in situ detection of enzyme activities on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE ) containing co-polymerized gelatine as substrate, in association with specific proteinase inhibitors. All 23 trypanosomatids expressed at least 1 acidic proteolytic enzyme. In addition, a characteristic and specific pattern of cell-associated metallo and/or cysteine proteinases was observed, except for the similar profiles detected in 2 Herpetomonas (H. anglusteri and H. samuelpessoai) and 3 Crithidia (C. fasciculata, C. guilhermei and C. luciliae) species. However, these flagellates released distinct secretory proteinase profiles into the extracellular medium. These findings strongly suggest that the association of cellular and secretory proteinase pattern could represent a useful marker to help trypanosomatid identification. PMID:15700759

  4. Viral and grazer regulation of prokaryotic growth efficiency in temperate freshwater pelagic environments.

    PubMed

    Pradeep Ram, A S; Colombet, Jonathan; Perriere, Fanny; Thouvenot, Antoine; Sime-Ngando, Telesphore

    2015-02-01

    In aquatic systems, limited data exists on the impact of mortality forces such as viral lysis and flagellate grazing when seeking to explain factors regulating prokaryotic metabolism. We explored the relative influence of top-down factors (viral lysis and heterotrophic nanoflagellate grazing) on prokaryotic mortality and their subsequent impact on their community metabolism in the euphotic zone of 21 temperate freshwater lakes located in the French Massif Central. Prokaryotic growth efficiency (PGE, index of prokaryotic community metabolism) determined from prokaryotic production and respiration measurements varied from 5 to 74% across the lakes. Viral and potential grazer-induced mortality of prokaryotes had contrasting impact on PGE. Potential flagellate grazing was found to enhance PGE whereas viral lysis had antagonistic impacts on PGE. The average PGE value in the grazing and viral lysis dominated lake water samples was 35.4% (±15.2%) and 17.2% (±8.1%), respectively. Selective viral lysis or flagellate grazing on prokaryotes together with the nature of contrasted substrates released through mortality processes can perhaps explain for the observed variation and differences in PGE among the studied lakes. The influences of such specific top-down processes on PGE can have strong implications on the carbon and nutrient fluxes in freshwater pelagic environments. PMID:25764557

  5. Mechanisms of phytoplankton adaptation to environmental variability in a shelf ecosystem

    NASA Astrophysics Data System (ADS)

    Barlow, R.; Lamont, T.; Britz, K.; Sessions, H.

    2013-11-01

    Phytoplankton absorption, pigments and active fluorescence were investigated at five focus sites in a shelf region during summer and winter to elucidate the adaptation of communities to changing environmental conditions. We determined that the availability of nutrients and changing irradiance were the key drivers of phytoplankton growth and photoacclimation in an ecosystem influenced by a warm western boundary current. Diatoms dominated the communities in the winter, while mixed diatom-flagellate populations generally prevailed in summer. Prokaryotes were dominant in the surface layer at one site where warm water flowed onto the shelf. Diatom and flagellate communities were associated with cooler, lower salinity water and prokaryotes with warm, higher salinity water. Populations appeared not be nutrient stressed and actively drew down silicates and nitrates, with nitrates being rapidly utilized resulting in low ambient nitrate levels in the upper water column. The phytoplankton acclimated to changing irradiance conditions by increasing the quantum yield of photochemistry with decreasing irradiance and adjusting the absorption of light by accessory pigments. Prokaryote dominated communities had high chlorophyll-specific absorption coefficients, and a high proportion of spectral absorption by chlorophyll a and photoprotective carotenoids. Diatoms had low chlorophyll-specific absorption and elevated absorption by photosynthetic carotenoids and chlorophyll c. Although flagellate-dominated communities had intermediate chlorophyll-specific absorption, their proportion of absorption by photosynthetic carotenoids and chlorophyll c was similar to the diatoms.

  6. Element stoichiometry of a mixotrophic protist grown under varying resource conditions.

    PubMed

    Chrzanowski, Thomas H; Lukomski, Natalie C; Grover, James P

    2010-01-01

    The balance of essential elements (e.g. carbon [C], nitrogen [N], and phosphorus [P]) between consumers and their resources influences not only the growth and reproduction of the consumers but also the nutrients they regenerate. Flagellate protists are significant predators of aquatic bacteria and directly influence nutrient flow to higher trophic levels and, through excretion, influence the mineral element composition of dissolved nutrients. Because the element stoichiometry of protists is poorly characterized, we varied the resource composition of the bacterium Pseudomonas fluorescens and used it to grow the mixotrophic bacterivorous flagellate Ochromonas danica. Using a mass balance approach, the element composition of O. danica was found to vary depending upon the nutrient composition of the prey and ranged between 482:36:1 and 80:12:1 (C:N:P molar). Homeostasis plots suggested that flagellate protists weakly regulate their element composition and are likely to regenerate different elements depending upon the nature of the element limiting growth of their prey. PMID:20561118

  7. Direct and Indirect Evidence of Size-Selective Grazing on Pelagic Bacteria by Freshwater Nanoflagellates

    PubMed Central

    Šimek, Karel; Chrzanowski, Thomas H.

    1992-01-01

    Size-selective grazing of three heterotrophic nanoflagellates (with cell sizes of 21, 44, and 66 μm3) isolated from Lake Arlington, Texas was examined by using a natural mixture of fluorescence labelled lake bacteria. Sizes of ingested bacteria in food vacuoles were directly measured. Larger bacterial cells were ingested at a frequency much higher than that at which they occurred in the assemblage, indicating preferential flagellate grazing on the larger size classes within the lake bacterioplankton. Water samples were collected biweekly from June through September, 1989, fractionated by filtration, and incubated for 40 h at in situ temperatures. The average bacterial size was always larger in water which was passed through 1-μm-pore-size filters (1-μm-filtered water) (which was predator free) than in 5-μm-filtered water (which contained flagellates only) or in unfiltered water (in which all bacterivores were present). The increase of bacterial-cell size in 1-μm-filtered water was caused by a shift in the size structure of the bacterioplankton population. Larger cells became more abundant in the absence of flagellate grazing. PMID:16348811

  8. Molecular Characterization of fliD Gene Encoding Flagellar Cap and Its Expression among Clostridium difficile Isolates from Different Serogroups

    PubMed Central

    Tasteyre, Albert; Karjalainen, Tuomo; Avesani, Véronique; Delmée, Michel; Collignon, Anne; Bourlioux, Pierre; Barc, Marie-Claude

    2001-01-01

    The fliD gene encoding the flagellar cap protein (FliD) of Clostridium difficile was studied in 46 isolates belonging to serogroups A, B, C, D, F, G, H, I, K, X, and S3, including 30 flagellated strains and 16 nonflagellated strains. In all but three isolates, amplification by PCR and reverse transcription-PCR demonstrated that the fliD gene is present and transcribed in both flagellated and nonflagellated strains. PCR-restriction fragment length polymorphism (RFLP) analysis of amplified fliD gene products revealed interstrain homogeneity, with one of two major patterns (a and b) found in all but one of the strains, which had pattern c. A polyclonal monospecific antiserum raised to the recombinant FliD protein reacted in immunoblots with crude flagellar preparations from 28 of 30 flagellated strains but did not recognize FliD from nonflagellated strains. The fliD genes from five strains representative of the three different RFLP groups were sequenced, and sequencing revealed 100% identity between the strains with the same pattern and 88% identity among strains with different patterns. Our results show that even though FliD is a structure exposed to the outer environment, the flagellar cap protein is very well conserved, and this high degree of conservation suggests that it has a very specific function in attachment to cell or mucus receptors. PMID:11230454

  9. Changes in lipid composition of copepods and Euphausia superba associated with diet and environmental conditions in the marginal ice zone, Bellingshausen Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Cripps, G. C.; Hill, H. J.

    1998-08-01

    The effect of varying diet and environmental conditions at the Marginal Ice Zone (MIZ) on the fatty acid and hydrocarbon compositions of five species of copepod and krill, Euphausia superba, was investigated. Zooplankton at the MIZ experienced a range of conditions, from a low algal biomass (mainly flagellates) under pack-ice to a spring bloom dominated by diatoms in the open ocean. Principal Component Analysis classified the copepods into three dietary regimes: (i) omnivores or general algal feeders under the pack ice, (ii) dinoflagellate feeders, and (iii) diatom feeders in the open ocean. This classification was supported by the distribution of the diatom marker n-heneicosahexaene ( n-C 21:6) and a general indicator of herbivory, the isoprenoid pristane. The fatty acid and hydrocarbon composition reflected dietary preferences and availability as the season progressed. Of the copepods under the pack-ice, Oithona spp. was omnivorous whereas Calanus propinquus was feeding preferentially on flagellates. Metridia gerlachei fed on flagellates in all conditions, but also included diatoms in its diet during the bloom. Calanoides acutus and Rhincalanus gigas, which passed the winter in diapause, were feeding almost exclusively on diatoms in the open ocean. Euphausia superba, which were also mainly diatom feeders in the open ocean, were feeding on the sea-ice algae (diatoms) and suspended material from the water column (dinoflagellates) under the pack-ice.

  10. Quantitative analysis of periodic chemotaxis in aggregation patterns of Dictyostelium discoideum

    NASA Astrophysics Data System (ADS)

    Steinbock, Oliver; Hashimoto, Hajime; Müller, Stefan C.

    1991-04-01

    Wave patterns in the cellular slime mold Dictyostelium discoideum are investigated quantitatively by determining the chemotactic motion of the amoebae cells towards their aggregation center. The velocity of moving cells is analyzed by a pixel-based correlation program applied to digital microscopic video images of approximately 0.4 × 0.3 mm 2 area. The average velocity component in the direction of the center is clearly periodic with periods of 6-9 min, a maximum velocity of 20 to 30 μm/min and a minimum velocity close to zero. Details concerning the asymmetric shape of the velocity function are observed. The new technique allows the detection of oscillating behaviour in chemotactic motion, even after the macroscopic patterns observed by dark-field techniques have disappeared.

  11. Noise places constraints on eukaryotic gradient sensing and chemotaxis

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Fuller, Danny; Loomis, William; Chen, Wen; Rappel, Wouter-Jan; Levine, Herbert

    2012-02-01

    Chemotaxis is characterized by the directional cell movement following external chemical gradients. It plays a crucial role in a variety of biological processes including neuronal development, wound healing and cancer metastasis. Ultimately, the accuracy of gradient sensing is limited by the fluctuations of signaling components, e.g. the stochastic receptor occupancy on cell surface. We use concepts and techniques from statistical physics, estimation theory, and information theory to quantify the stochastic and nonlinear information processing in eukaryotic chemotaxis. We mainly address the following questions: (1) What are the physical limits of eukaryotic spatial gradient sensing? (2) How to characterize the movements of chemotactic cells? (3) How much gradient information can be reliably gained by a chemotactic cell? By answering those questions, we expect to derive new insights for general biological signal processing systems.

  12. Decreased chemotaxis of human peripheral phagocytes exposed to a strong static magnetic field.

    PubMed

    Sipka, S; Szöllosi, I; Batta, Gy; Szegedi, Gy; Illés, A; Bakó, Gy; Novák, D

    2004-01-01

    The chemotaxis of human peripheral phagocytes, neutrophils and monocytes was examined in a strong static magnetic field (0.317+/-0.012 Tesla). The chemotaxis of the suspension of purified neutrophils and monocytes was tested in the Boyden chamber using C5a as a chemotactic signal. The chambers were placed into a temperature regulated (36.6 degrees C) equipment producing a strong static magnetic field (0.317 Tesla) for 60 minutes. The movement of cells proceeded into a nitrocellulose membrane toward the north-pole of the magnet, i.e. in the direction of the Earth's gravitational pull. The C5a induced chemotaxis of human neutrophils decreased significantly in the strong static magnetic field. Monocytes were not significantly effected. The strong static magnetic field decreased the chemotactic movement of neutrophils and this phenomenon may have implications when humans are exposed to magnetic resonance imaging for extended periods of time. PMID:15334831

  13. E. coli chemotaxis and super-diffusion

    NASA Astrophysics Data System (ADS)

    Dobnikar, Jure; Matthäus, Franziska; Jagodic, Marko

    2010-03-01

    The bacteria E. coli actively propel by switching between clockwise and anti-clockwise rotation of the flagella attached to their cell membranes. This results in two modes of motion: tumbling and swimming. The switching between the two modes is coupled to the ligand sensing through the chemotactic signalling pathway inside the cell. We modelled the signalling pathway and performed numerical simulations of the chemotactic motion of a large number of E. coli bacteria under various external conditions. We have shown that under certain conditions the thermal noise in the level of receptor-bound CheR (an enzyme responsible for methylation of the receptor sites) leads to super-diffusive behaviour (L'evy walk) which is advantageous for the bacterial populations in environments with scarce food. Exerting external pressure we might observe evolution of the wild-type to the super-diffusive populations.

  14. Chemotaxis: Under Agarose Assay.

    PubMed

    Brazill, Derrick

    2016-01-01

    The unicellular eukaryote Dictyostelium discoideum represents a superb model for examining chemotaxis. Under vegetative conditions, the amoebae are chemotactically responsive to pterins, such as folate. Under starved conditions, they lose their sensitivity to pterins, and become chemotactically responsive to cAMP. As an NIH model system, Dictyostelium offers a variety of advantages in studying chemotaxis, including its conservation of mammalian signaling pathways, its ease of growth, and its genetic tractability. In this chapter, we describe the use of the under agarose chemotaxis assay to identify proteins involved in controlling motility and directional sensing in Dictyostelium discoideum. Given the similarities between Dictyostelium and mammalian cells, this allows us to dissect the conserved pathways involved in eukaryotic chemotaxis. PMID:26498795

  15. New development in studies of formyl-peptide receptors: critical roles in host defense.

    PubMed

    Li, Liangzhu; Chen, Keqiang; Xiang, Yi; Yoshimura, Teizo; Su, Shaobo; Zhu, Jianwei; Bian, Xiu-wu; Wang, Ji Ming

    2016-03-01

    Formyl-peptide receptors are a family of 7 transmembrane domain, Gi-protein-coupled receptors that possess multiple functions in many pathophysiologic processes because of their expression in a variety of cell types and their capacity to interact with a variety of structurally diverse, chemotactic ligands. Accumulating evidence demonstrates that formyl-peptide receptors are critical mediators of myeloid cell trafficking in the sequential chemotaxis signal relays in microbial infection, inflammation, and immune responses. Formyl-peptide receptors are also involved in the development and progression of cancer. In addition, one of the formyl-peptide receptor family members, Fpr2, is expressed by normal mouse-colon epithelial cells, mediates cell responses to microbial chemotactic agonists, participates in mucosal development and repair, and protects against inflammation-associated tumorigenesis. These novel discoveries greatly expanded the current understanding of the role of formyl-peptide receptors in host defense and as potential molecular targets for the development of therapeutics. PMID:26701131

  16. [Granulocyte adherence and chemotaxis in children (author's transl)].

    PubMed

    Rister, M; Horatz, M

    1981-01-01

    Granulocyte adherence to endothelial surfaces associated with their chemotactic property enables these cells to leave the peripheral blood and to migrate into the tissue. This study was performed to investigate the effect of bacterial and viral infections as well as various kinds of therapies on these leukocyte functions. The adherence of control granulocytes to nylon fibers was 70%. In contrast to viral infections bacterial infections increased the adherence to 91%. Following the treatment with high dose methotrexate or vincristine the adherence was reduced to 20%. This granulocyte function defect was evident up to 14 days after the high dose methotrexate infusion. An age dependency of granulocyte adherence was not observed. In addition, viral infections as well as cytostatic therapy did not effect granulozyte chemotaxis. But bacterial infections and various defined phagocytic defects impaired the granulocyte chemotactic activity. PMID:7193772

  17. Exosomes Mediate LTB4 Release during Neutrophil Chemotaxis.

    PubMed

    Majumdar, Ritankar; Tavakoli Tameh, Aidin; Parent, Carole A

    2016-01-01

    Leukotriene B4 (LTB4) is secreted by chemotactic neutrophils, forming a secondary gradient that amplifies the reach of primary chemoattractants. This strategy increases the recruitment range for neutrophils and is important during inflammation. Here, we show that LTB4 and its synthesizing enzymes localize to intracellular multivesicular bodies that, upon stimulation, release their content as exosomes. Purified exosomes can activate resting neutrophils and elicit chemotactic activity in a LTB4 receptor-dependent manner. Inhibition of exosome release leads to loss of directional motility with concomitant loss of LTB4 release. Our findings establish that the exosomal pool of LTB4 acts in an autocrine fashion to sensitize neutrophils towards the primary chemoattractant, and in a paracrine fashion to mediate the recruitment of neighboring neutrophils in trans. We envision that this mechanism is used by other signals to foster communication between cells in harsh extracellular environments. PMID:26741884

  18. Folate responsiveness during growth and development of Dictyostelium: separate but related pathways control chemotaxis and gene regulation.

    PubMed

    Blusch, J H; Nellen, W

    1994-01-01

    Folate-controlled gene expression and chemotaxis have been examined in Dictyostelium wild-type and mutant strains. We show that regulation of the discoidin genes is sensitive to folate in growing cells as well as in suspension development. The signal is transferred via the N10-methylfolate-sensitive folate receptor sites, which also appear to confer the chemotactic response. The strain HG5145 has previously been isolated as a mutant that does not display chemotactic movement towards folate. Nevertheless, these cells are fully functional in folate-mediated downregulation of discoidin I expression. The strain ga 93 has been isolated as an overproducer mutant of the cyclic nucleotide phosphodiesterase inhibitor. Simultaneously, these cells fail to downregulate discoidin I in response to folate but are fully functional in folate chemotaxis. Therefore we conclude that the pathways for chemotaxis and for gene regulation diverge downstream of a common receptor type. PMID:8170395

  19. Defective neutrophil chemotaxis in juvenile periodontitis.

    PubMed Central

    Clark, R A; Page, R C; Wilde, G

    1977-01-01

    Neutrophil chemotaxis was evaluated in nine patients with juvenile periodontitis, with normal subjects and patients with the adult form of periodontitis as controls. Defective chemotactic responses were observed in neutrophils from seven of nine juvenile patients, and a reduced level of complement-derived chemotactic activity was demonstrated in serum from four patients. These determinations were normal in all the patients with adult periodontitis. Serum from five of the juvenile patients contained a heat-stable, non-dialyzable factor that markedly inhibited the chemotaxis of normal neutrophils. Thus the characteristic tissue destruction seen in juvenile periodontitis may be, at least in part, a consequence of a failure of host defense mechanisms. PMID:591063

  20. Function and Regulation of Heterotrimeric G Proteins during Chemotaxis

    PubMed Central

    Kamp, Marjon E.; Liu, Youtao; Kortholt, Arjan

    2016-01-01

    Chemotaxis, or directional movement towards an extracellular gradient of chemicals, is necessary for processes as diverse as finding nutrients, the immune response, metastasis and wound healing. Activation of G-protein coupled receptors (GPCRs) is at the very base of the chemotactic signaling pathway. Chemotaxis starts with binding of the chemoattractant to GPCRs at the cell-surface, which finally leads to major changes in the cytoskeleton and directional cell movement towards the chemoattractant. Many chemotaxis pathways that are directly regulated by Gβγ have been identified and studied extensively; however, whether Gα is just a handle that regulates the release of Gβγ or whether Gα has its own set of distinct chemotactic effectors, is only beginning to be understood. In this review, we will discuss the different levels of regulation in GPCR signaling and the downstream pathways that are essential for proper chemotaxis. PMID:26784171