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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. 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.

  3. Structure and seasonal dynamics of the protozoan community (heterotrophic flagellates, ciliates, amoeboid protozoa) in the plankton of a large river (River Danube, Hungary).

    PubMed

    Kiss, Aron Keve; Acs, Eva; Kiss, Keve Tihamér; Török, Júlia Katalin

    2009-05-01

    Seasonal dynamics of all major protozoan groups were investigated in the plankton of the River Danube, upstream of Budapest (Hungary), by bi-weekly sampling over a 1-year long period. Sixty-one heterotrophic flagellate, 14 naked amoeba, 50 testate amoeba, 4 heliozoan and 83 ciliate morphospecies were identified. The estimated abundance ranges of major groups throughout the year were as follows: heterotrophic flagellates, 0.27-7.8 x 10(6)ind.l(-1); naked amoebae, max. 3300ind.l(-1); testaceans, max. 1600ind.l(-1); heliozoans, max. 8500ind.l(-1); ciliates, 132-34,000ind.l(-1). In terms of biovolume, heterotrophic flagellates dominated throughout the year (max. 0.58mm(3)l(-1)), and ciliates only exceeded their biovolume in summer (max. 0.76mm(3)l(-1)). Naked amoeba and heliozoan biovolume was about one, and testacean biovolume 1-3, orders of magnitude lower than that of ciliates. In winter, flagellates, mainly chrysomonads, had the highest biomass, whilst ciliates were dominated by peritrichs. In 2005 from April to July a long spring/summer peak occurred for all protozoan groups. Beside chrysomonads typical flagellates were choanoflagellates, bicosoecids and abundant microflagellates (large chrysomonads and Collodictyon). Most abundant ciliates were oligotrichs, while Phascolodon, Urotricha, Vorticella, haptorids, Suctoria, Climacostomum and Stokesia also contributed significantly to biovolume during rapid succession processes. In October and November a second high protozoan peak occurred, with flagellate dominance, and slightly different taxonomic composition.

  4. The cell biology of peritrichous flagella in Bacillus subtilis.

    PubMed

    Guttenplan, Sarah B; Shaw, Sidney; Kearns, Daniel B

    2013-01-01

    Bacterial flagella are highly conserved molecular machines that have been extensively studied for assembly, function and gene regulation. Less studied is how and why bacteria differ based on the number and arrangement of the flagella they synthesize. Here we explore the cell biology of peritrichous flagella in the model bacterium Bacillus subtilis by fluorescently labelling flagellar basal bodies, hooks and filaments. We find that the average B. subtilis cell assembles approximately 26 flagellar basal bodies and we show that basal body number is controlled by SwrA. Basal bodies are assembled rapidly (< 5 min) but the assembly of flagella capable of supporting motility is rate limited by filament polymerization (> 40 min). We find that basal bodies are not positioned randomly on the cell surface. Rather, basal bodies occupy a grid-like pattern organized symmetrically around the midcell and that flagella are discouraged at the poles. Basal body position is genetically determined by FlhF and FlhG homologues to control spatial patterning differently from what is seen in bacteria with polar flagella. Finally, spatial control of flagella in B. subtilis seems more relevant to the inheritance of flagella and motility of individual cells than the motile behaviour of populations.

  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. Chemotactic separation of enzymes.

    PubMed

    Dey, Krishna Kanti; Das, Sambeeta; Poyton, Matthew F; Sengupta, Samudra; Butler, Peter J; Cremer, Paul S; Sen, Ayusman

    2014-12-23

    We demonstrate a procedure for the separation of enzymes based on their chemotactic response toward an imposed substrate concentration gradient. The separation is observed within a two-inlet, five-outlet microfluidic network, designed to allow mixtures of active (ones that catalyze substrate turnover) and inactive (ones that do not catalyze substrate turnover) enzymes, labeled with different fluorophores, to flow through one of the inlets. Substrate solution prepared in phosphate buffer was introduced through the other inlet of the device at the same flow rate. The steady-state concentration profiles of the enzymes were obtained at specific positions within the outlets of the microchannel using fluorescence microscopy. In the presence of a substrate concentration gradient, active enzyme molecules migrated preferentially toward the substrate channel. The excess migration of the active enzyme molecules was quantified in terms of an enrichment coefficient. Experiments were carried out with different pairs of enzymes. Coupling the physics of laminar flow of liquid and molecular diffusion, multiphysics simulations were carried out to estimate the extent of the chemotactic separation. Our results show that, with appropriate microfluidic arrangement, molecular chemotaxis leads to spontaneous separation of active enzyme molecules from their inactive counterparts of similar charge and size.

  7. Hydrodynamics of freely swimming flagellates

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Flagellates are a diverse group of unicellular organisms forming an important part of the marine ecosystem. The arrangement of flagella around the cell serves as a key trait optimizing and compromising essential functions. With micro-particle image velocimetry we observed time-resolved near-cell flows around freely swimming flagellates, and we developed an analytical model based on the Stokes flow around a solid sphere propelled by a variable number of differently placed, temporally varying point forces, each representing one flagellum. The model allows us to reproduce the observed flow patterns and swimming dynamics, and to extract quantities such as swimming velocities and prey clearance rates as well as flow disturbances revealing the organism to flow-sensing predators. Our results point to optimal flagellar arrangements and beat patterns, and essential trade-offs. For biflagellates with two symmetrically arranged flagella we contrasted two species using undulatory and ciliary beat patterns, respectively, and found breast-stroke type beat patterns with equatorial power strokes to be favorable for fast as well as quiet swimming. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

  8. Flagellate dermatitis after consumption of Shiitake mushrooms

    PubMed Central

    Kreft, Burkhard; Marsch, Wolfgang Ch.

    2014-01-01

    Flagellate dermatitis occurs in patients who have eaten Shiitake mushrooms. We are reporting on a 55-year-old man, who developed whiplash-striped, severely itching efflorescences on the trunk 3 days after eating Lentinula edodes. Flagellate dermatitis is also known as a cutaneous side effect of bleomycin therapy. PMID:25097492

  9. 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.

  10. 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

  11. 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.

  12. Growth of the peritrich epibiont Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) estimated from laboratory experiments.

    PubMed

    Utz, L R P

    2008-05-01

    Peritrich ciliates are commonly found colonizing living substrates. Although this a well known phenomenon, biological aspects of this relationship need to be studied in more detail. Assessment of growth rates in peritrichs has been the subject of very few studies. Only species in the genera Carchesium Ehrenberg, 1830 and Vorticella Linnaeus, 1767 had their growth rates evaluated in the field and in the laboratory. In the present study, growth, colonization (colonies/host), and proliferation (zooids/colony) rates of the peritrich epibiont Zoothamnium intermedium Precht, 1935 attached to the calanoid copepod Acartia tonsa Dana 1848 were evaluated in the laboratory in two food regimes: bacteria only, and algal based diet. Results showed that growth, colonization, and proliferation rates were similar for both diets. Maximum growth rates obtained for Z. intermedium was 0.85 and 0.83 per day, for bacteria and algae respectively. Maximum colonization rates were 0.5 per day for both diets, and the maximum proliferation rates were 0.44 and 0.42 per day for bacteria and algae respectively. These results demonstrate that Z. intermedium is able to grow at the same rate of other peritrichs on bacterial and algal based diets.

  13. Adsorption kinetics of laterally and polarly flagellated Vibrio.

    PubMed Central

    Belas, M R; Colwell, R R

    1982-01-01

    The adsorption of laterally and polarly flagellated bacteria to chitin was measured, and from the data obtained, a modified Langmuir adsorption isotherm was derived. Results indicated that the adsorption of laterally flagellated Vibrio parahaemolyticus follows the Langmuir adsorption isotherm, a type of adsorption referred to as surface saturation kinetics, when conditions are favorable for the production of lateral flagella. When conditions were not favorable for the production of lateral flagella, bacterial adsorption did not follow the Langmuir adsorption isotherm; instead, proportional adsorption kinetics were observed. The adsorption of some polarly flagellated bacteria exhibited surface saturation kinetics. However, the binding index (the product of the number of binding sites and bacterial affinity to the surface) of polarly flagellated bacteria differed significantly from that of laterally flagellated bacteria, suggesting that polarly flagellated bacteria adsorb to chitin by a different mechanism from that used by the laterally flagellated bacteria. From the results of dual-label adsorption competition experiments, in which polarly flagellated V. cholerae competed with increasing concentrations of laterally flagellated V. parahaemolyticus, it was observed that laterally flagellated bacteria inhibited the adsorption of polarly flagellated bacteria. In contrast, polarly flagellated bacteria enhanced the adsorption of V. cholerae. In competition experiments, where V. parahaemolyticus competed against increasing concentrations of other bacteria, polarly flagellated bacteria enhanced V. parahaemolyticus adsorption significantly, whereas laterally flagellated bacteria only slightly enhanced the process. The direct correlation observed between surface saturation kinetics, the production of lateral flagella, and the ability of laterally flagellated bacteria to inhibit the adsorption of polarly flagellated bacteria suggests that lateral flagella represent a

  14. Putative bronchopulmonary flagellated protozoa in immunosuppressed patients.

    PubMed

    Kilimcioglu, Ali Ahmet; Havlucu, Yavuz; Girginkardesler, Nogay; Celik, Pınar; Yereli, Kor; Özbilgin, Ahmet

    2014-01-01

    Flagellated protozoa that cause bronchopulmonary symptoms in humans are commonly neglected. These protozoal forms which were presumed to be "flagellated protozoa" have been previously identified in immunosuppressed patients in a number of studies, but have not been certainly classified so far. Since no human cases of bronchopulmonary flagellated protozoa were reported from Turkey, we aimed to investigate these putative protozoa in immunosuppressed patients who are particularly at risk of infectious diseases. Bronchoalveolar lavage fluid samples of 110 immunosuppressed adult patients who were admitted to the Department of Chest Diseases, Hafsa Sultan Hospital of Celal Bayar University, Manisa, Turkey, were examined in terms of parasites by light microscopy. Flagellated protozoal forms were detected in nine (8.2%) of 110 cases. Metronidazole (500 mg b.i.d. for 30 days) was given to all positive cases and a second bronchoscopy was performed at the end of the treatment, which revealed no parasites. In conclusion, immunosuppressed patients with bronchopulmonary symptoms should attentively be examined with regard to flagellated protozoa which can easily be misidentified as epithelial cells.

  15. Putative Bronchopulmonary Flagellated Protozoa in Immunosuppressed Patients

    PubMed Central

    Kilimcioglu, Ali Ahmet; Havlucu, Yavuz; Çelik, Pınar; Özbilgin, Ahmet

    2014-01-01

    Flagellated protozoa that cause bronchopulmonary symptoms in humans are commonly neglected. These protozoal forms which were presumed to be “flagellated protozoa” have been previously identified in immunosuppressed patients in a number of studies, but have not been certainly classified so far. Since no human cases of bronchopulmonary flagellated protozoa were reported from Turkey, we aimed to investigate these putative protozoa in immunosuppressed patients who are particularly at risk of infectious diseases. Bronchoalveolar lavage fluid samples of 110 immunosuppressed adult patients who were admitted to the Department of Chest Diseases, Hafsa Sultan Hospital of Celal Bayar University, Manisa, Turkey, were examined in terms of parasites by light microscopy. Flagellated protozoal forms were detected in nine (8.2%) of 110 cases. Metronidazole (500 mg b.i.d. for 30 days) was given to all positive cases and a second bronchoscopy was performed at the end of the treatment, which revealed no parasites. In conclusion, immunosuppressed patients with bronchopulmonary symptoms should attentively be examined with regard to flagellated protozoa which can easily be misidentified as epithelial cells. PMID:24804259

  16. Renal flagellate infections in reptiles: 29 cases.

    PubMed

    Juan-Sallés, Caries; Garner, Michael M; Nordhausen, Robert W; Valls, Xavier; Gallego, Miguel; Soto, Sara

    2014-03-01

    Renal infection with flagellated protozoa was retrospectively evaluated in 29 reptiles, including 12 turtles, 7 tortoises, and 6 chameleons; overall, 20 species of reptiles were represented. Most cases presented with nonspecific clinical signs or a combination of several concurrent diseases. Nineteen of 29 reptiles had tubulointerstitial nephritis associated with flagellates, and this lesion was considered contributory to death in 15 cases, although concurrent diseases were frequent. Infection was invasive into the renal interstitium in three reptiles due to tubular rupture and in one chameleon also spread to adjacent tissues, coelomic cavity, and blood vessels due to renal rupture. Cytologic or ultrastructural evaluation of trophozoites in two cases was consistent with diplomonad flagellates. Renal disease was often complicated with soft-tissue mineralization and/or gout. Gastrointestinal and cloacal infection with flagellates and inflammation were frequent in reptiles in which the digestive tract was available for histopathologic examination, and this supports the possibility of infections ascending the urinary tract from the cloaca. Renal disease associated with flagellate protozoa is rare in vertebrates but appears to be relevant in reptiles, particularly chelonians and chameleons.

  17. Chemotactic collapse and mesenchymal morphogenesis

    NASA Astrophysics Data System (ADS)

    Escudero, Carlos

    2005-08-01

    We study the effect of chemotactic signaling among mesenchymal cells. We show that the particular physiology of the mesenchymal cells allows one-dimensional collapse in contrast to the case of bacteria, and that the mesenchymal morphogenesis represents thus a more complex type of pattern formation than those found in bacterial colonies. We compare our theoretical predictions with recent in vitro experiments.

  18. Hydrodynamic effects on the tumbling of flagellated bacteria near a solid surface

    NASA Astrophysics Data System (ADS)

    Molaei, Mehdi; Sheng, Jian

    2011-11-01

    Peritrichously flagellated bacteria use semi-rigid helical flagella to form a bundle during a run to swim forward and to trigger the unbundling during a tumble to change their swimming direction. It is accepted that the hydrodynamic interactions play a significant role in these processes. Recently, using digital holographic microscopy and microfluidics, we discovered that the tumbling events are substantially suppressed near a solid wall. In this paper, we present a two flagellum rigid model to elucidate the hydrodynamic wall interaction mechanism behind the phenomenon. Further implications on cell attachment and detachment during the biofilm formation will be discussed. We apply Slender Body Theory (SBT) to quantify the flow flagellum interaction. The no-slip boundary imposed by the wall is modeled using the image system of the SBT model for the stoke-flow singularity. We show that in the bulk, a repulsive force among flagella initiates the unbundling and consequently tumbling; however, in presence of the wall, the force is strongly mitigated that stabilize the bundle and suppress the tumbling. NIH and NSF.

  19. An analytical model of flagellate hydrodynamics

    NASA Astrophysics Data System (ADS)

    Dölger, Julia; Bohr, Tomas; Andersen, Anders

    2017-04-01

    Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical solution by Oseen for the low Reynolds number flow due to a point force outside a no-slip sphere. The no-slip sphere represents the cell and the point force a single flagellum. By superposition we are able to model a freely swimming flagellate with several flagella. For biflagellates with left–right symmetric flagellar arrangements we determine the swimming velocity, and we show that transversal forces due to the periodic movements of the flagella can promote swimming. For a model flagellate with both a longitudinal and a transversal flagellum we determine radius and pitch of the helical swimming trajectory. We find that the longitudinal flagellum is responsible for the average translational motion whereas the transversal flagellum governs the rotational motion. Finally, we show that the transversal flagellum can lead to strong feeding currents to localized capture sites on the cell surface.

  20. Chemotactic Blebbing in Dictyostelium Cells.

    PubMed

    Zatulovskiy, Evgeny; Kay, Robert R

    2016-01-01

    Many researchers use the social amoeba Dictyostelium discoideum as a model organism to study various aspects of the eukaryotic cell chemotaxis. Traditionally, Dictyostelium chemotaxis is considered to be driven mainly by branched F-actin polymerization. However, recently it has become evident that Dictyostelium, as well as many other eukaryotic cells, can also employ intracellular hydrostatic pressure to generate force for migration. This process results in the projection of hemispherical plasma membrane protrusions, called blebs, that can be controlled by chemotactic signaling.Here we describe two methods to study chemotactic blebbing in Dictyostelium cells and to analyze the intensity of the blebbing response in various strains and under different conditions. The first of these methods-the cyclic-AMP shock assay-allows one to quantify the global blebbing response of cells to a uniform chemoattractant stimulation. The second one-the under-agarose migration assay-induces directional blebbing in cells moving in a gradient of chemoattractant. In this assay, the cells can be switched from a predominantly F-actin-driven mode of motility to a bleb-driven chemotaxis, allowing one to compare the efficiency of both modes and explore the molecular machinery controlling chemotactic blebbing.

  1. A new flagship peritrich (Ciliophora, Peritrichida) from the River Rhine, Germany: Apocarchesium arndti n. sp.

    PubMed

    Norf, Helge; Foissner, Wilhelm

    2010-01-01

    We discovered a free-living peritrich ciliate with outstanding features in the River Rhine. Its morphology and 18S rRNA gene sequence were studied with standard methods. Apocarchesium arndti n. sp. has several peculiarities. (i) There are ordinary zooids, macrozooids, and microzooids, which form a hemispherical rosette on a discoidal base, the stalk dish, locking the approximately 18 microm wide and up to 2 mm long, spirally contracting colony stalk. (ii) The stalk myoneme is connected only to the microzooids. (iii) A rosette contains up to 50 zooids not connected to each other but individually attached to the stalk dish with the scopula. (iv) The ordinary zooids are epistylidid, trumpet-shaped (approximately 6:1 length:width), about 180 x 30 microm in size, and have an ellipsoidal macronucleus subapically between oral cavity and dorsal side. (v) The myoneme system of the zooids, which can contract individually, forms a tube-like structure in the narrow posterior half of the cell. (vi) The silverline pattern belongs to the transverse-striate type. (vii) The oral apparatus is of usual structure, with kinety 1 of peniculus 3 distinctly shortened proximally. (viii) The 18S rRNA places A. arndti n. sp. as a distinct lineage near Vorticella and Carchesium. These data are used to provide an improved diagnosis of the genus Apocarchesium. Features (i)-(iii) and the molecular data indicate that Apocarchesium could be the type genus of a new peritrich family.

  2. A New Flagship Peritrich (Ciliophora, Peritrichida) from the River Rhine, Germany: Apocarchesium arndti n. sp.

    PubMed Central

    NORF, HELGE; FOISSNER, WILHELM

    2011-01-01

    We discovered a free-living peritrich ciliate with outstanding features in the River Rhine. Its morphology and 18S rRNA gene sequence were studied with standard methods. Apocarchesium arndti n. sp. has several peculiarities. (i) There are ordinary zooids, macrozooids, and microzooids, which form a hemispherical rosette on a discoidal base, the stalk dish, locking the ~ 18 μm wide and up to 2 mm long, spirally contracting colony stalk. (ii) The stalk myoneme is connected only to the microzooids. (iii) A rosette contains up to 50 zooids not connected to each other but individually attached to the stalk dish with the scopula. (iv) The ordinary zooids are epistylidid, trumpet-shaped (~ 6:1 length:width), about 180 × 30 μm in size, and have an ellipsoidal macronucleus subapically between oral cavity and dorsal side. (v) The myoneme system of the zooids, which can contract individually, forms a tube-like structure in the narrow posterior half of the cell. (vi) The silverline pattern belongs to the transverse-striate type. (vii) The oral apparatus is of usual structure, with kinety 1 of peniculus 3 distinctly shortened proximally. (viii) The 18S rRNA places A. arndti n. sp. as a distinct lineage near Vorticella and Carchesium. These data are used to provide an improved diagnosis of the genus Apocarchesium. Features (i)–(iii) and the molecular data indicate that Apocarchesium could be the type genus of a new peritrich family. PMID:20337807

  3. 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

  4. 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.

  5. Flagellated bacterial motility in polymer solutions

    PubMed Central

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

    2014-01-01

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

  6. On Flagellar Structure in Certain Flagellates

    PubMed Central

    Gibbons, I. R.; Grimstone, A. V.

    1960-01-01

    This paper describes the structure of the flagella, basal bodies, and some of the associated fibre systems in three genera of complex flagellates, Trichonympha, Pseudotrichonympha, and Holomastigotoides. Three groups of longitudinal fibres occur in a flagellum: two central and nine outer fibres such as have been repeatedly described in other material, and an additional set of nine smaller secondary fibres not previously identified as such. Each central fibre shows a helical substructure; the pair of them are enveloped in a common sheath. Each outer fibre is a doublet with one subfibre bearing projections—called arms—that extend toward the adjacent outer fibre. The basal body is formed by a cylinder of nine triplet outer fibres. Two subfibres of each triplet continue into the flagellum and constitute the doublets. The third subfibre terminates at the transition of basal body to flagellum, possibly giving rise to the nine radial transitional fibres that seem to attach the end of the basal body to the surface of the organism. The central and secondary flagellar fibres are not present in the lumen of the basal body, but other complex structures occur there. The form of these intraluminal structures differs from genus to genus. The flagellar unit is highly asymmetrical. All the flagella examined have possessed the same one of the two possible enantiomorphic forms. At least two systems of fibres are associated with the basal bodies of all three genera. PMID:13827900

  7. 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.

  8. Flagellated bacterial motility in polymer solutions.

    PubMed

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

    2014-12-16

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

  9. 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

  10. Taxonomic characterization of Vorticella fuscaPrecht, 1935 and Vorticella parapulchella n. sp., two marine peritrichs (Ciliophora, Oligohymenophorea) from China.

    PubMed

    Sun, Ping; Song, Weibo; Clamp, John; Al-Rasheid, Khaled A S

    2006-01-01

    Two marine peritrich ciliates, Vorticella fuscaPrecht (1935) and Vorticella parapulchella n. sp. were discovered in the littoral zone of Qingdao, northern China. Their morphology, infraciliature, and silverline system were described using live observation and silver impregnation. The poorly known species V. fusca is redescribed, adding information about the oral infraciliature and pellicular morphology. Vorticella parapulchella n. sp. is superficially similar to Vorticella pulchellaSommer (1951) but is distinguished from it by being markedly smaller and having much more widely spaced pellicular ridges. The infundibular infraciliature of V. parapulchella is extremely unusual in having infundibular polykinety 3 reduced to two rows, one of which has almost disappeared.

  11. Kinetic and hydrodynamic models of chemotactic aggregation

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri; Sire, Clément

    2007-10-01

    We derive general kinetic and hydrodynamic models of chemotactic aggregation that describe certain features of the morphogenesis of biological colonies (like bacteria, amoebae, endothelial cells or social insects). Starting from a stochastic model defined in terms of N coupled Langevin equations, we derive a nonlinear mean-field Fokker-Planck equation governing the evolution of the distribution function of the system in phase space. By taking the successive moments of this kinetic equation and using a local thermodynamic equilibrium condition, we derive a set of hydrodynamic equations involving a damping term. In the limit of small frictions, we obtain a hyperbolic model describing the formation of network patterns (filaments) and in the limit of strong frictions we obtain a parabolic model which is a generalization of the standard Keller-Segel model describing the formation of clusters (clumps). Our approach connects and generalizes several models introduced in the chemotactic literature. We discuss the analogy between bacterial colonies and self-gravitating systems and between the chemotactic collapse and the gravitational collapse (Jeans instability). We also show that the basic equations of chemotaxis are similar to nonlinear mean-field Fokker-Planck equations so that a notion of effective generalized thermodynamics can be developed.

  12. 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.

  13. Chemotactic peptide receptor modulation in polymorphonuclear leukocytes

    PubMed Central

    1980-01-01

    The binding of the chemotactic peptide N- formylnorleucylleucylphenylalanine (FNLLP) to its receptor on rabbit polymorphonuclear leukocytes (PMNs) modulates the number of available peptide receptors. Incubation with FNLLP decreases subsequent binding capacity, a phenomenon that has been termed receptor down regulation. Down regulation of the chemotactic peptide receptor is concentration dependent in both the rate and extent of receptor loss. The dose response parallels that of FNLLP binding to the recptor. The time- course is rapid; even at concentrations of FNLLP as low as 3 x 10(-9) M, the new equilibrium concentration of receptors is reached within 15 min. Down regulation is temperature dependent, but does occur even at 4 degrees C. Concomitant with down regulation, some of the peptide becomes irreversibly cell associated. At 4 degrees C, there is a small accumulation of nondissociable peptide that rapidly reaches a plateau. At higher temperatures, accumulation of nondissociable peptide continues after the rceptor number has reached equilibrium, and the amount accumulated can exceed the initial number of receptors by as much as 300%. The dose response of peptide uptake at 37 degrees C reflects that of binding, suggesting that it is receptor mediated. This uptake may occur via a pinocytosis mechanism. Although PMNs have not been considered to be pinocytic, the addition of FNLLP causes a fourfold stimulation of the rate of pinocytosis as measured by the uptake of [3H]sucrose. PMID:7391138

  14. 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.

  15. Some Mixotrophic Flagellate Species Selectively Graze on Archaea.

    PubMed

    Ballen-Segura, Miguel; Felip, Marisol; Catalan, Jordi

    2017-01-15

    Many phototrophic flagellates ingest prokaryotes. This mixotrophic trait becomes a critical aspect of the microbial loop in planktonic food webs because of the typical high abundance of these flagellates. Our knowledge of their selective feeding upon different groups of prokaryotes, particularly under field conditions, is still quite limited. In this study, we investigated the feeding behavior of three species (Rhodomonas sp., Cryptomonas ovata, and Dinobryon cylindricum) via their food vacuole content in field populations of a high mountain lake. We used the catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) protocol with probes specific for the domain Archaea and three groups of Eubacteria: Betaproteobacteria, Actinobacteria, and Cytophaga-Flavobacteria of Bacteroidetes Our results provide field evidence that contrasting selective feeding exists between coexisting mixotrophic flagellates under the same environmental conditions and that some prokaryotic groups may be preferentially impacted by phagotrophic pressure in aquatic microbial food webs. In our study, Archaea were the preferred prey, chiefly in the case of Rhodomonas sp., which rarely fed on any other prokaryotic group. In general, prey selection did not relate to prey size among the grazed groups. However, Actinobacteria, which were clearly avoided, mostly showed a size of <0.5 μm, markedly smaller than cells from the other groups.

  16. Eosinophil chemotactic factors from cysticercoids of Hymenolepis nana.

    PubMed

    Niwa, A; Asano, K; Ito, A

    1998-09-01

    A comparative study of eosinophil chemotactic factors was carried out using cysticercoids and oncospheres of Hymenolepis nana. Cysticercoids showed twice the chemotactic activity for eosinophils than the oncospheres. Eosinophilia induced by oncospheres and cysticercoids observed in secondary and primary infections, respectively, were discussed from the view point of the immunobiology of this parasite.

  17. 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.

  18. 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.

  19. Classification of the peritrich ciliate Opisthonecta matiensis (Martín-Cereceda et al. 1999) as Telotrochidium matiense nov. comb., based on new observations and SSU rDNA phylogeny.

    PubMed

    Martín-Cereceda, Mercedes; Guinea, Almudena; Bonaccorso, Elisa; Dyal, Patricia; Novarino, Gianfranco; Foissner, Wilhelm

    2007-11-01

    New observations on Opisthonecta matiensis Martín-Cereceda et al. [1999. Description of Opisthonecta matiensis n. sp. (Protozoa, Ciliophora), a new peritrich ciliate from wastewater. J. Eukaryot. Microbiol. 46, 283-289] especially the lack of an epistomial membrane, reveal that the species does not belong to the genus Opisthonecta, but to Telotrochidium, the other genus within the family Opisthonectidae Foissner, 1975. The contractile vacuole and the cytopyge are on the dorsal wall of the vestibulum and the trochal band is limited distally and proximally by rows of narrowly spaced pellicular pores. Thus the species is redefined as Telotrochidium matiense nov. comb. The morphological, cortical and nuclear events occurring during conjugation are illustrated, compared with those in other species, and phylogenetically discussed. Invariably, the microconjugants attach to and penetrate the lateral side of the macroconjugants. Nuclear processes are very similar to those reported from other peritrichs. The small subunit rRNA gene (SSU rDNA) is sequenced and the phylogeny within Opisthonectidae and peritrichs examined. T. matiense is more closely related to Epistylis (63% Maximum Parsimony (MP), 85% Maximum Likelihood (ML)) than to any other genus, while another representative of the family, viz., Opisthonecta henneguyi, is closely related to Vorticella microstoma, Astylozoon enriquesi and clone RT3n18 (100% MP, 100% ML). Morphology and gene sequences suggest that Telotrochidium and Opisthonecta have derived from different lineages of stalked peritrichs: Opisthonecta could have arisen from peritrichs with stalk myonemes, while Telotrochidium probably evolved from peritrichs without stalk myonemes.

  20. Gradient sensing in defined chemotactic fields

    PubMed Central

    Skoge, Monica; Adler, Micha; Groisman, Alex; Levine, Herbert; Loomis, William F.; Rappel, Wouter-Jan

    2011-01-01

    Cells respond to a variety of secreted molecules by modifying their physiology, growth patterns, and behavior. Motile bacteria and eukaryotic cells can sense extracellular chemoattractants and chemorepellents and alter their movement. In this way fibroblasts and leukocytes can find their ways to sites of injury and cancer cells can home in on sites that are releasing growth factors. Social amoebae such as Dictyostelium are chemotactic to cAMP which they secrete several hours after they have initiated development. These eukaryotic cells are known to be able to sense extremely shallow gradients but the processes underlying their exquisite sensitivity are still largely unknown. In this study we determine the responses of developed cells of Dictyostelium discoideum to stable linear gradients of cAMP of varying steepness generated in 2 μm deep gradient chambers of microfluidic devices. The gradients are generated by molecular diffusion between two 50 μm deep flow-through channels, one of which is perfused with a solution of cAMP and the other with buffer, serving as continuously replenished source and sink. These low ceiling gradient chambers constrained the cells in the vertical dimension, facilitating confocal imaging, such that subcellular localization of fluorescently tagged proteins could be followed for up to 30 minutes without noticeable phototoxicity. Chemotactic cells enter these low ceiling chambers by flattening and elongating and then move almost as rapidly as unconstrained cells. By following the localization of activated Ras (RasGTP) using a Ras Binding Domain fused to Green Fluorescent Protein (RBD-GFP), we observed the rapid appearance of membrane associated patches at the tips of pseudopods. These patches remained associated with pseudopods while they continued to extend but were rapidly disassembled when pseudopods stalled and the cell moved past them. Likewise, fluorescence associated with localized RasGTP rapidly disappeared when the gradient was

  1. Cellulose Metabolism by the Termite Flagellate Trichomitopsis termopsidis

    PubMed Central

    Yamin, Michael A.

    1980-01-01

    The end products of cellulose metabolism by the trichomonad flagellate Trichomitopsis termopsidis from the termite Zootermopsis sp. were investigated by growing axenic flagellates on [14C]cellulose. The growth of T. termopsidis resulted in the release of label into the supernatant fraction of the culture fluid, and > 75% was volatile under acid conditions. The label was analyzed for 14CO2 and for [14C]volatile compounds by vacuum distillation under acid and alkaline conditions in disposable micro-distillation vessels. The distillate and undistilled culture supernatant fluid were chromatographed on cellulose thin layers to identify the labeled end product. T. termopsidis produced 14CO2 and [14C]acetate which accounted for 25 to 30% and 55 to 60% of the labeled end products, respectively. The ratio of label in CO2 to acetate suggests that they are produced in equimolar amounts. No neutral volatile compounds were produced. The remaining unidentified end product (10 to 20%) was not volatile nor extractable into ether. Hydrogen was produced by T. termopsidis, and the cells were killed by the drug metronidazole. Enzymatic activities were found which account for these end products: pyruvate:ferredoxin oxidoreductase and hydrogenase. The results indicate that acetate is the end product of T. termopsidis cellulose metabolism and is available to the termite for energy metabolism and biosynthesis. PMID:16345549

  2. 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.

  3. 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.

  4. Numerical simulations of flagellated micro-swimmers and ciliated surfaces

    NASA Astrophysics Data System (ADS)

    Shum, Henry; Tripathi, Anurag; Yeomans, Julia; Balazs, Anna

    2013-03-01

    Cilia are filamentous organelles found in many organisms for achieving locomotion or for driving fluid flows within the body. Cilia-like structures can be constructed and have potential for application in microfluidics, where they may be used to locally control flow and the motion of particles in the fluid. We implement a lattice Boltzmann method to simulate fluid flows produced by externally actuated artificial cilia and explore the influence of such cilia on objects in the surrounding fluid. In particular, we show examples of interactive effects between cilia arrays and self-motile swimmers propelled by a rotating helical flagellum. Artificial swimmers mimicking the motion of flagellated bacteria in this way have been experimentally realized in recent years and our simulations produce testable predictions for the behavior of such swimmers in the presence of cilia.

  5. Long-term cultivation of the flagellate Euglena gracilis.

    PubMed

    Porst, M; Lebert, M; Hader, D P

    1997-01-01

    Euglena gracilis, a unicellular photosynthetic flagellate, serves as a model system in signal transduction research. To further study its complex gravitaxis, experiments under microgravity are desirable. In preparation for long-term experiments on a space station, an autonomous cultivation unit has been developed and the culture conditions and surveillance methods have been established. The running time of more than 600 d under closed conditions with light as the only source of energy confirmed the stability of the Euglena population and gave new insights into its behavior. Physicochemical parameters such as oxygen concentration, temperature and pH as well as physiological parameters including cell density, motility, gravitactic orientation and pigmentation were recorded on a frequent basis. The suitability of the botanical bioreaction to serve as an oxygen supplier for animals in a closed system was demonstrated.

  6. 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).

  7. Automated real-time measurement of chemotactic cell motility.

    PubMed

    Hadjout, N; Laevsky, G; Knecht, D A; Lynes, M A

    2001-11-01

    We have developed a novel method, (ECIS/taxis), for monitoring cell movement in response to chemotactic and chemokinetic factors. In this system, cells migrate in an under-agarose environment, and their positions are monitored using the electric cell-substrate impedance sensor technology to measure the impedance change at a target electrode, that is lithographed onto the substrate, as the cells arrive at the target. In the studies reported here, Dictyostelium discoideum was used as a prototypical, motile eukaryotic cell. Using the ECIS/taxis system, the arrival of cells at the target electrode was proportional to the dose offolate used to stimulate the cells and could be assessed by changes in resistance at the electrode. ECIS/taxis was readily able to distinguish between wild-type cells and a mutant that is deficient in its chemotactic response. Finally, we have shown that an agent that interferes with chemotactic motility leads to the delayed arrival of cells at the target electrode. The multi-well assay configuration allows for simultaneous automated screening of many samples for chemotactic or anti-chemotactic activity. This assay system is compatible with measurements of mammalian cell movement and should be valuable in the assessment of both agonists and antagonists of cell movement.

  8. 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

  9. 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

  10. Signaling Noise Enhances Chemotactic Drift of E. coli

    NASA Astrophysics Data System (ADS)

    Flores, Marlo; Shimizu, Thomas S.; ten Wolde, Pieter Rein; Tostevin, Filipe

    2012-10-01

    Noise in the transduction of chemotactic stimuli to the flagellar motor of E. coli will affect the random run-and-tumble motion of the cell and the ability to perform chemotaxis. Here we use numerical simulations to show that an intermediate level of noise in the slow methylation dynamics enhances drift while not compromising localization near concentration peaks. A minimal model shows how such an optimal noise level arises from the interplay of noise and the dependence of the motor response on the network output. Our results suggest that cells can exploit noise to improve chemotactic performance.

  11. [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

  12. 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.

  13. 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

  14. Dispersion of flagellated swimming microorganisms in planar Poiseuille flow

    NASA Astrophysics Data System (ADS)

    Chilukuri, Sandeep; Collins, Cynthia H.; Underhill, Patrick T.

    2015-03-01

    The presence of an external fluid flow significantly impacts the properties of swimming microorganisms between two surfaces. By performing computer simulations of dilute populations of flagellated swimming microorganisms, we calculate the dispersivity of the microorganisms at different flow rates by tracking each individual organism in the direction of the flow. Our results show how the dispersion of swimming microorganisms is different from passive particles. For low flow rates, the dispersivity is higher than that of non-motile organisms because of their swimming motion. As the flow rate increases, the dispersivity drops, reaching a minimum before increasing at high flow rates. The minimum occurs approximately when the swimming speed of the organism equals the mean velocity of the external flow. A scaling analysis is used to qualitatively capture the dispersion at both low and high flow rates. Closed-form expressions for the dispersivity were derived at low and high flow rates using an analytical theory. This analysis showed that at low flow rates, the alignment of the organisms by the flow is responsible for the reduction of the dispersion in comparison to the dispersion without any external flow. At high flow rates, the distribution and dynamics across the channel produce a dispersivity that is lower than that of passive particles.

  15. 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 ...

  16. 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...

  17. Controlled architectural and chemotactic studies of 3D cell migration.

    PubMed

    Tayalia, Prakriti; Mazur, Eric; Mooney, David J

    2011-04-01

    Chemotaxis plays a critical role in tissue development and wound repair, and is widely studied using ex vivo model systems in applications such as immunotherapy. However, typical chemotactic models employ 2D systems that are less physiologically relevant or use end-point assays, that reveal little about the stepwise dynamics of the migration process. To overcome these limitations, we developed a new model system using microfabrication techniques, sustained drug delivery approaches, and theoretical modeling of chemotactic agent diffusion. This model system allows us to study the effects of 3D architecture and chemotactic agent gradient on immune cell migration in real time. We find that dendritic cell migration is characterized by a strong interplay between matrix architecture and chemotactic gradients, and migration is also influenced dramatically by the cell activation state. Our results indicate that Lipopolysaccharide-activated dendritic cells studied in a traditional transwell system actually exhibit anomalous migration behavior. Such a 3D ex vivo system lends itself for analyzing cell migratory behavior in response to single or multiple competitive cues and could prove useful in vaccine development.

  18. Morphology of four new solitary sessile peritrich ciliates from the Yellow Sea, China, with description of an unidentified species of Paravorticella (Ciliophora, Peritrichia).

    PubMed

    Sun, Ping; Al-Farraj, Saleh A; Warren, Alan; Ma, Honggang

    2017-02-01

    Sessile peritrichs are a large assemblage of ciliates that have a wide distribution in soil, freshwater and marine waters. Here, we document four new and one unidentified species of solitary sessile peritrichs from aquaculture ponds and coastal waters of the northern Yellow Sea, China. Based on their living morphology, infraciliature and silverline system, four of the five forms were identified as new members belonging to one of three genera, Vorticella, Pseudovorticella and Scyphidia, representing two families, Vorticellidae and Scyphidiidae. The other isolate was found to be an unidentified species of the poorly known genus Paravorticella. Vorticella chiangi sp. nov. is characterized by its inverted bell-shaped zooid, short row 3 in infundibular polykinety 3 and marine habitat. Pseudovorticella liangae sp. nov. posseses a thin, broad peristomial lip and a granular pellicle. Pseudovorticella haiboensis sp. nov. is differentiated from its congeners by having an elongated zooid that is covered by a layer of thin pellicular vesicles, and two rows of kineties in infundibular polykinety 3. Scyphidia perezuzae sp. nov. and Paravorticella sp. are stalkless ectoparasites or ectocommensals of aquatic animals. The former has a short, plump body, a narrow peristomial lip and a conspicuous, flattened, disc-shaped scopula for adhesion. Paravorticella sp. has an extremely elongated clavate body, a broad peristomial lip, and a narrow scopula.

  19. Reconsideration of the phylogenetic positions of five peritrich genera, Vorticella, Pseudovorticella, Zoothamnopsis, Zoothamnium, and Epicarchesium (Ciliophora, Peritrichia, Sessilida), based on small subunit rRNA gene sequences.

    PubMed

    Li, Lifang; Song, Weibo; Warren, Alan; Shin, Mann Kyoon; Chen, Zigui; Ji, Daode; Sun, Ping

    2008-01-01

    In order to re-evaluate the systematics of sessilid peritrich ciliates, small subunit (SSU) rRNA gene sequences were determined for 12 species belonging to five genera: Vorticella, Pseudovorticella, Epicarchesium, Zoothamnium, and Zoothamnopsis. Phylogenetic trees were deduced using Bayesian inference, maximum parsimony, and maximum likelihood methods. The phylogenetic analyses suggest that (1) sessilids which have stalks with continuous myonemes that contract in a zig-zag fashion form a separate clade from those which have stalks that contract independently and in a spiral fashion, supporting the separation of the family Zoothamniidae from the family Vorticellidae and (2) Epicarchesium and Pseudovorticella, both of which have reticulate silverline systems, are more closely related to each other than to other vorticellids, suggesting that differences in the silverline system (i.e. transverse vs. reticulate) may be the result of genuine evolutionary divergence among sessilid peritrichs. However, the newly sequenced Zoothamnopsis sinica, which has a reticulate silverline pattern, nests within the unresolved Zoothamnium species that have transverse silverline patterns. Thus, there were at least two evolutions of the reticulate silverline pattern character state from a plesiomorphic transverse state in the peritrichid ciliates. The molecular work demonstrates the genus Zoothamnium to be paraphyletic in relation to morphological studies, and suggests that Astylozoon, Opisthonecta, and Vorticella microstoma possibly share a SSU rRNA secondary structure in the helix E10-1 region.

  20. Surface structures (peritrichous fibrils and tufts of fibrils) found on Streptococcus sanguis strains may be related to their ability to coaggregate with other oral genera.

    PubMed Central

    Handley, P S; Carter, P L; Wyatt, J E; Hesketh, L M

    1985-01-01

    We screened 36 strains of Streptococcus sanguis biotype I and 8 strains of S. sanguis biotype II for the presence of surface structures and for their ability to coaggregate with Actinomyces viscosus, Actinomyces naeslundii, and Fusobacterium nucleatum. Negative staining under an electron microscope revealed detectable surface structures on all S. sanguis strains. The majority of strains (38 of 44) carried peritrichous fibrils, which have an irregular profile and no distinct width. They usually appeared as a fringe with a constant width around the cell. Strains selected for measurement had a fringe with an average length of 72.4 +/- 8.5 nm on biotype I strains and 51.6 +/- 3.3 nm on biotype II strains. Some fibrillar biotype I strains carried an additional, longer (158.7 +/- 33.1 nm) type of fibril projecting through the shorter fibrils. Fibrillar density was characteristic for each strain, ranging from very dense on all cells in a population to very sparse on a few cells in a population. A small group of six strains carried tufts of fibrils in a lateral or polar position on the cell. Either one or two lengths of fibril were present in the tuft depending on the strain. One strain carried both peritrichous fibrils and fimbriae. Fimbriae are flexible structures with a constant width (4.5 to 5.0 nm) all along their length but very variable lengths (less than or equal to 0.7 micron) on each cell. S. sanguis I and II both included strains with peritrichous fibrils and tufts of fibrils, but the mixed morphotype strain was confined to biotype II. Fibrils were present on cells at all stages throughout the growth cycle for the strains tested. Freshly isolated fibrillar strains coaggregated consistently well with A. viscosus and A. naeslundii, although some fibrillar reference strains lacked the ability. In addition, all tufted strains could not coaggregate, but the strains with the mixed morphotype coaggregated well. Coaggregation with F. nucleatum was very strong for the

  1. Analysis of bacterial chemotactic response using dynamic laser speckle

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  2. 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.

  3. 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.

  4. Culturing bias in marine heterotrophic flagellates analyzed through seawater enrichment incubations.

    PubMed

    del Campo, Javier; Balagué, Vanessa; Forn, Irene; Lekunberri, Itziar; Massana, Ramon

    2013-10-01

    The diversity of heterotrophic flagellates is generally based on cultivated strains, on which ultrastructural, physiological, and molecular studies have been performed. However, the relevance of these cultured strains as models of the dominant heterotrophic flagellates in the marine planktonic environment is unclear. In fact, molecular surveys typically recover novel eukaryotic lineages that have refused cultivation so far. This study was designed to directly address the culturing bias in planktonic marine heterotrophic flagellates. Several microcosms were established adding increasing amounts and sources of organic matter to a confined natural microbial community pre-filtered by 3 μm. Growth dynamics were followed by epifluorescence microscopy and showed the expected higher yield of bacteria and heterotrophic flagellates at increased organic matter additions. Moreover, protist diversity analyzed by molecular tools showed a clear substitution in the community, which differed more and more from the initial sample as the organic matter increased. Within this gradient, there was also an increase of sequences related to cultured organisms as well as a decrease in diversity. Culturing bias is partly explained by the use of organic matter in the isolation process, which drives a shift in the community to conditions closer to laboratory cultures. An intensive culturing effort using alternative isolation methods is necessary to allow the access to the missing heterotrophic flagellates that constitute the abundant and active taxa in marine systems.

  5. Conditions for self-consistent aggregation by chemotactic particles

    NASA Astrophysics Data System (ADS)

    Inoue, Masayo; Kaneko, Kunihiko

    2008-04-01

    We have numerically studied chemotactic aggregation of microorganisms by introducing a model consisting of elements with intracellular dynamics, random walks with a state-dependent turnover rate, and secretion of attractant. Three phases with and without aggregation, as well as partial aggregation, were obtained as to the diffusion and degradation rates of the attractant, and conditions for cellular aggregation were analyzed. The size of aggregated clusters was shown to be independent of cell density, as is consistent with experiment.

  6. Polarised clathrin-mediated endocytosis of EGFR during chemotactic invasion.

    PubMed

    Mutch, Laura Jane; Howden, Jake Davey; Jenner, Emma Poppy Louise; Poulter, Natalie Sarah; Rappoport, Joshua Zachary

    2014-06-01

    Directed cell migration is critical for numerous physiological processes including development and wound healing. However chemotaxis is also exploited during cancer progression. Recent reports have suggested links between vesicle trafficking pathways and directed cell migration. Very little is known about the potential roles of endocytosis pathways during metastasis. Therefore we performed a series of studies employing a previously characterised model for chemotactic invasion of cancer cells to assess specific hypotheses potentially linking endocytosis to directed cell migration. Our results demonstrate that clathrin-mediated endocytosis is indispensable for epidermal growth factor (EGF) directed chemotactic invasion of MDA-MB-231 cells. Conversely, caveolar endocytosis is not required in this mode of migration. We further found that chemoattractant receptor (EGFR) trafficking occurs by clathrin-mediated endocytosis and is polarised towards the front of migrating cells. However, we found no role for clathrin-mediated endocytosis in focal adhesion disassembly in this migration model. Thus, this study has characterised the role of endocytosis during chemotactic invasion and has identified functions mechanistically linking clathrin-mediated endocytosis to directed cell motility.

  7. Polarised Clathrin-Mediated Endocytosis of EGFR During Chemotactic Invasion

    PubMed Central

    Mutch, Laura Jane; Howden, Jake Davey; Jenner, Emma Poppy Louise; Poulter, Natalie Sarah; Rappoport, Joshua Zachary

    2014-01-01

    Directed cell migration is critical for numerous physiological processes including development and wound healing. However chemotaxis is also exploited during cancer progression. Recent reports have suggested links between vesicle trafficking pathways and directed cell migration. Very little is known about the potential roles of endocytosis pathways during metastasis. Therefore we performed a series of studies employing a previously characterised model for chemotactic invasion of cancer cells to assess specific hypotheses potentially linking endocytosis to directed cell migration. Our results demonstrate that clathrin-mediated endocytosis is indispensable for epidermal growth factor (EGF) directed chemotactic invasion of MDA-MB-231 cells. Conversely, caveolar endocytosis is not required in this mode of migration. We further found that chemoattractant receptor (EGFR) trafficking occurs by clathrin-mediated endocytosis and is polarised towards the front of migrating cells. However, we found no role for clathrin-mediated endocytosis in focal adhesion disassembly in this migration model. Thus, this study has characterised the role of endocytosis during chemotactic invasion and has identified functions mechanistically linking clathrin-mediated endocytosis to directed cell motility. PMID:24921075

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

    PubMed

    Sommaruga, Ruben; Kandolf, Georg

    2014-02-17

    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.

  9. Stimulation of human neutrophil leukocyte aerobic glucose metabolism by purified chemotactic factors.

    PubMed Central

    Goetzl, E J; Austen, K F

    1974-01-01

    The interaction of human neutrophils adherent to plastic petri dishes with the purified chemotactic factors C5a and kallikrein increased their rate of aerobic glycolysis 25-120% and the activity of their hexose monophosphate shunt (HMPS) 100-600%, reaching a plateau after 2 hr at 37 degrees C. The stimulation of either pathway required a chemotactically active stimulus since neither C5 nor prekallikrein or inactivated kallikrein could enhance metabolic activity. Marked suppression of the neutrophil chemotactic response by preincubation with a chemotactic factor to achieve deactivation, 5 x 10(-7) M diisopropyl fluorophosphate, or the neutrophil immobilizing factor (NIF) did not prevent the stimulation of HMPS activity or glycolysis by chemotactic factors. The metabolic inhibitors iodoacetate and 6-aminonicotinamide at concentrations which blocked enhancement of glycolysis or HMPS activity, respectively, partially suppressed the chemotactic response of neutrophils to the chemotactic factors. The capacity of a chemotactic factor to stimulate glucose metabolism of human neutrophils is associated with a maximal chemotactic response, but this stimulation is not alone sufficient for chemotaxis. Images PMID:11344574

  10. CHANGES IN THE MORPHOLOGY AND POLYSACCHARIDE CONTENT OF MICROCYSTIS AERUGINOSA (CYANOBACTERIA) DURING FLAGELLATE GRAZING(1).

    PubMed

    Yang, Zhou; Kong, Fanxiang; Shi, Xiaoli; Zhang, Min; Xing, Peng; Cao, Huansheng

    2008-06-01

    To investigate the changes in the morphology and polysaccharide content of Microcystis aeruginosa (Kütz.) Kütz. during flagellate grazing, cultures of M. aeruginosa were exposed to grazing Ochromonas sp. for a period of 9 d under controlled laboratory conditions. M. aeruginosa responded actively to flagellate grazing and formed colonies, most of which were made up of several or dozens of cells, suggesting that flagellate grazing may be one of the biotic factors responsible for colony formation in M. aeruginosa. When colonies were formed, the cell surface ultrastructure changed, and the polysaccharide layer on the surface of the cell wall became thicker. This change indicated that synthesis and secretion of extracellular polysaccharide (EPS) of M. aeruginosa cells increased under flagellate grazing pressure. The contents of soluble extracellular polysaccharide (sEPS), bound extracellular polysaccharide (bEPS), and total polysaccharide (TPS) in colonial cells of M. aeruginosa increased significantly compared with those in single cells. This finding suggested that the increased amount of EPS on the cell surface may play a role in keeping M. aeruginosa cells together to form colonies.

  11. 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

  12. 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.

  13. Chemotactic and Phagocytic Activity of Blood Neutrophils in Allergic Asthma.

    PubMed

    Mosca, Tainá; Menezes, Maria C S; Silva, Ademir Veras; Stirbulov, Roberto; Forte, Wilma C N

    2015-01-01

    Allergic asthma is a chronic inflammatory airway disease, and has been considered a T helper-2-biased response. Studies suggest that neutrophils may be associated with exacerbation and asthma severity. We sought to evaluate the chemotactic activity and phagocytic capacity by peripheral blood neutrophils from individuals with controlled and uncontrolled allergic asthma, and compare the results with non-asthmatic controls groups. Blood neutrophils were isolated from 95 patients: 24 with controlled asthma, 24 uncontrolled asthma, 24 healthy subjects and 23 patients with IgE-mediated allergies other than asthma. The neutrophil chemotaxis, stimulated with LPS, autologous serum or homologous serum, was determined using Boyden chambers. The phagocytic capacity was assessed by ingestion of zimosan particles, and digestion phase was analyzed by NBT test. The phagocytic digestion phase and chemotaxis by neutrophils from asthmatic patients was higher than in non-asthmatic controls (p  < 0.05). Autologous serum-induced neutrophil chemotaxis in patients with uncontrolled asthma was greater (p  < 0.05) than in other study groups. The ingestion phase of phagocytosis showed similar values in asthmatics and non-asthmatics. We conclude that the blood neutrophil from controlled and uncontrolled asthmatic patients exhibit activation markers, particularly phagocytic digestion and chemotactic activities.

  14. Modelling Chemotactic Motion of Cells in Biological Tissues

    PubMed Central

    Vasiev, Bakhtier

    2016-01-01

    Developmental processes in biology are underlined by proliferation, differentiation and migration of cells. The latter two are interlinked since cellular differentiation is governed by the dynamics of morphogens which, in turn, is affected by the movement of cells. Mutual effects of morphogenetic and cell movement patterns are enhanced when the movement is due to chemotactic response of cells to the morphogens. In this study we introduce a mathematical model to analyse how this interplay can result in a steady movement of cells in a tissue and associated formation of travelling waves in a concentration field of morphogen. Using the model we have identified four chemotactic scenarios for migration of single cell or homogeneous group of cells in a tissue. Such a migration can take place if moving cells are (1) repelled by a chemical produced by themselves or (2) attracted by a chemical produced by the surrounding cells in a tissue. Furthermore, the group of cells can also move if cells in surrounding tissue are (3) repelled by a chemical produced by moving cells or (4) attracted by a chemical produced by surrounding cells themselves. The proposed mechanisms can underlie migration of cells during embryonic development as well as spread of metastatic cells. PMID:27798687

  15. Impaired neutrophil directional chemotactic accuracy in chronic periodontitis patients

    PubMed Central

    Roberts, Helen M; Ling, Martin R; Insall, Robert; Kalna, Gabriela; Spengler, Julia; Grant, Melissa M; Chapple, Iain LC

    2015-01-01

    Aim To investigate the chemotactic accuracy of peripheral blood neutrophils from patients with chronic periodontitis compared with matched healthy controls, before and after non-surgical periodontal therapy. Material & Methods Neutrophils were isolated from patients and controls (n = 18) by density centrifugation. Using the Insall chamber and video microscopy, neutrophils were analysed for directional chemotaxis towards N-formyl-methionyl-leucyl-phenylalanine [fMLP (10 nM), or CXCL8 (200 ng/ml)]. Circular statistics were utilized for the analysis of cell movement. Results Prior to treatment, neutrophils from patients with chronic periodontitis had significantly reduced speed, velocity and chemotactic accuracy compared to healthy controls for both chemoattractants. Following periodontal treatment, patient neutrophils continued to display reduced speed in response to both chemoattractants. However, velocity and accuracy were normalized for the weak chemoattractant CXCL8 while they remained significantly reduced for fMLP. Conclusions Chronic periodontitis is associated with reduced neutrophil chemotaxis, and this is only partially restored by successful treatment. Dysfunctional neutrophil chemotaxis may predispose patients with periodontitis to their disease by increasing tissue transit times, thus exacerbating neutrophil-mediated collateral host tissue damage. PMID:25360483

  16. Acquired chemotactic inhibitors during infection with guinea pig cytomegalovirus.

    PubMed Central

    Tannous, R; Myers, M G

    1983-01-01

    Factors involved in neutrophil and monocyte migrations were serially studied in strain 2 guinea pigs undergoing initial cytomegalovirus infection and sham-inoculated controls. All studies remained unchanged in uninfected animals. Monocyte migrations and neutrophil spontaneous migration remained unchanged in infected animals. However, transient abnormalities occurred early in infection, comprising a decrease in neutrophil-directed migration towards C5-derived chemotactic fractions (C5-fr) and a decrease in the chemotactic activity of zymosan-activated plasma. Consequently, the presence of neutrophil- and chemotaxin-directed inhibitors in plasma was investigated. Normal neutrophils, C5-fr, Escherichia coli-derived bacterial factor, and the synthetic peptide F-met-leu-phe were first incubated with control or infected plasmas and then assayed for directed migration and lysosomal enzyme release. Results indicated the de novo appearance of both neutrophil- and chemotaxin-directed inhibitory activities in plasma during early infection. The neutrophil-directed inhibition was heat stable (56 degrees C for 120 min) and nonspecific (responses to all chemotaxins were inhibited). The chemotaxin-directed inhibition was heat stable and C5-fr specific. The cytomegalovirus-induced inhibitors may be important in the enhanced susceptibility to concurrent opportunistic infections. PMID:6305847

  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 %).

  18. Precise computations of chemotactic collapse using moving mesh methods

    NASA Astrophysics Data System (ADS)

    Budd, C. J.; Carretero-González, R.; Russell, R. D.

    2005-01-01

    We consider the problem of computing blow-up solutions of chemotaxis systems, or the so-called chemotactic collapse. In two spatial dimensions, such solutions can have approximate self-similar behaviour, which can be very challenging to verify in numerical simulations [cf. Betterton and Brenner, Collapsing bacterial cylinders, Phys. Rev. E 64 (2001) 061904]. We analyse a dynamic (scale-invariant) remeshing method which performs spatial mesh movement based upon equidistribution. Using a suitably chosen monitor function, the numerical solution resolves the fine detail in the asymptotic solution structure, such that the computations are seen to be fully consistent with the asymptotic description of the collapse phenomenon given by Herrero and Velázquez [Singularity patterns in a chemotaxis model, Math. Ann. 306 (1996) 583-623]. We believe that the methods we construct are ideally suited to a large number of problems in mathematical biology for which collapse phenomena are expected.

  19. 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.

  20. The Autophagy Machinery: A New Player in Chemotactic Cell Migration

    PubMed Central

    Coly, Pierre-Michaël; Gandolfo, Pierrick; Castel, Hélène; Morin, Fabrice

    2017-01-01

    Autophagy is a highly conserved self-degradative process that plays a key role in diverse cellular processes such as stress response or differentiation. A growing body of work highlights the direct involvement of autophagy in cell migration and cancer metastasis. Specifically, autophagy has been shown to be involved in modulating cell adhesion dynamics as well as epithelial-to-mesenchymal transition. After providing a general overview of the mechanisms controlling autophagosome biogenesis and cell migration, we discuss how chemotactic G protein-coupled receptors, through the repression of autophagy, may orchestrate membrane trafficking and compartmentation of specific proteins at the cell front in order to support the critical steps of directional migration. PMID:28261054

  1. 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.

  2. Aquacells — Flagellates under long-term microgravity and potential usage for life support systems

    NASA Astrophysics Data System (ADS)

    Häder, Donat-P.; Richter, Peter R.; Strauch, S. M.; Schuster, M.

    2006-09-01

    The motile behavior of the unicellular photosynthetic flagellate Euglena gracilis was studied during a two-week mission on the Russian satellite Foton M2. The precision of gravitactic orientation was high before launch and, as expected, the cells were unoriented during microgravity. While after previous short-term TEXUS flights the precision of orientation was as high as before launch, it took several hours for the organisms to regain their gravitaxis. Also the percentage of motile cells and the swimming velocity of the remaining motile cells were considerably lower than in the ground control. In preparatory experiments the flagellate Euglena was shown to produce considerable amounts of photosynthetically generated oxygen. In a coupling experiment in a prototype for a planned space mission on Foton M3, the photosynthetic producers were shown to supply sufficient amounts of oxygen to a fish compartment with 35 larval cichlids, Oreochromis mossambicus.

  3. Active stress driven convection in a suspension of chemotactic bacteria

    NASA Astrophysics Data System (ADS)

    Kasyap, T. V.; Koch, Donald

    2011-11-01

    We examine the linear stability of a suspension of swimming bacteria producing dipolar hydrodynamic disturbances confined in a channel subjected to a linear chemo-attractant gradient across the channel. At the continuum level swimming bacteria exert an ``active'' stress on the fluid which is a function of the bacterial concentration and orientation fields. In the base-state without any fluid flow, the fluxes from the chemotactic and diffusive motion of the bacteria balance to yield exponential number density and active stress profiles across the channel. We show that such a base-state is unstable to perturbations in the number density parallel to the channel walls if the bacterial concentration exceeds a critical value determined by a Peclet number measuring the strength of chemotaxis relative to diffusion. Active stress gradients resulting from the perturbation in the number density drive convective fluid flow, which transports bacteria into the regions of highest perturbed bacteria concentration reinforcing the original perturbation. We examine the linear stability of a suspension of swimming bacteria producing dipolar hydrodynamic disturbances confined in a channel subjected to a linear chemo-attractant gradient across the channel. At the continuum level swimming bacteria exert an ``active'' stress on the fluid which is a function of the bacterial concentration and orientation fields. In the base-state without any fluid flow, the fluxes from the chemotactic and diffusive motion of the bacteria balance to yield exponential number density and active stress profiles across the channel. We show that such a base-state is unstable to perturbations in the number density parallel to the channel walls if the bacterial concentration exceeds a critical value determined by a Peclet number measuring the strength of chemotaxis relative to diffusion. Active stress gradients resulting from the perturbation in the number density drive convective fluid flow, which transports

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

    PubMed

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

    2014-04-06

    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.

  5. 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

  6. Population Structure of Endomicrobia in Single Host Cells of Termite Gut Flagellates (Trichonympha spp.)

    PubMed Central

    Zheng, Hao; Dietrich, Carsten; Thompson, Claire L.; Meuser, Katja; Brune, Andreas

    2015-01-01

    The gut microbiota of many phylogenetically lower termites is dominated by the cellulolytic flagellates of the genus Trichonympha, which are consistently associated with bacterial symbionts. In the case of Endomicrobia, an unusual lineage of endosymbionts of the Elusimicrobia phylum that is also present in other gut flagellates, previous studies have documented strict host specificity, leading to the cospeciation of “Candidatus Endomicrobium trichonymphae” with their respective flagellate hosts. However, it currently remains unclear whether one Trichonympha species is capable of harboring more than one Endomicrobia phylotype. In the present study, we selected single Trichonympha cells from the guts of Zootermopsis nevadensis and Reticulitermes santonensis and characterized their Endomicrobia populations based on internal transcribed spacer (ITS) region sequences. We found that each host cell harbored a homogeneous population of symbionts that were specific to their respective host species, but phylogenetically distinct between each host lineage, corroborating cospeciation being caused by vertical inheritance. The experimental design of the present study also allowed for the identification of an unexpectedly large amount of tag-switching between samples, which indicated that any high-resolution analysis of microbial community structures using the pyrosequencing technique has to be interpreted with great caution. PMID:25739443

  7. Transmission and ecology of trypanosomatid flagellates of water striders (Hemiptera: Gerridae).

    PubMed

    Tieszen, K L; Molyneux, D H

    1989-01-01

    An investigation of transmission and ecology of the monogenetic trypanosomatids, Blastocrithidia gerridis and Crithidia flexonema, in Gerris is described. Motile free-living flagellates of both species were found in the faeces of Gerris and in the water on which the bugs inhabited. Transmission of both trypanosomatid species occurred from naturally infected wild-caught bugs to flagellate-free laboratory-bred bugs via water. Crithidia flexonema was also transmitted to laboratory-bred bugs after being isolated in culture. Observations of experimentally infected bugs indicate that C. flexonema flagellates are imbibed and pass through the fore- and midgut to the hindgut where they become attached and multiply. There was no evidence to suggest transovarial transmission. In a 3-yr investigation into the prevalence of trypanosomatids in a natural population of adult Gerris odontogaster, it was found that the infection rate varied between 19% and 100%. There was no significant difference in infection rates between females and males. The infection rate peaked for each year in late spring or early summer. The significance of these results is discussed in relation to the ecology and behaviour of Gerris. The results indicate that the infections are maintained in hibernating bugs over winter.

  8. Enhancement of chemotactic response to sodium acetate in the nematode Caenorhabditis elegans.

    PubMed

    Matsuura, Tetsuya; Oda, Takayuki; Hayashi, Genta; Sugisaki, Daisuke; Ichinose, Mitsuyuki

    2010-08-01

    In this study, we investigated the chemotactic response of a wild-type (N2) nematode (Caenorhabditis elegans) to a water-soluble attractant, sodium acetate, after pre-exposure to the chemical. The chemotactic response to 1.0 M sodium acetate of the non-exposed control nematodes was lower than that of the nematodes that were pre-exposed to 1.0 M sodium acetate for 90 min (p < 0.05). The increase in the response to sodium acetate was observed up to 6 hr, but not at 12 hr after exposure. To clarify the mechanism of this enhancement of the chemotactic response, several mutants were used. The chemotactic response of pre-exposed tph-1 and bas-1 mutants, whose main defect was serotonin secretion, was enhanced in comparison with that of the control mutants (p < 0.01). However, cat-1 and cat-2 mutants, which are respectively defective in serotonin and dopamine secretion and dopamine secretion only, showed no enhancement of the chemotactic response to sodium acetate, even when pre-exposed to this chemical. When the cat-1 and cat-2 mutants were pre-exposed to sodium acetate and bred in the presence of 40 mM dopamine, these mutants showed enhanced chemotactic response to sodium acetate (p < 0.05). These results suggest that the enhancement of chemotactic response to sodium acetate after pre-exposure to this chemical is modulated by dopaminergic neurotransmission.

  9. Spasmogenic activity of chemotactic N-formylated oligopeptides: identity of structure--function relationships for chemotactic and spasmogenic activities.

    PubMed

    Marasco, W A; Fantone, J C; Ward, P A

    1982-12-01

    The chemotactic N-formylated oligopeptides are potent spasmogenic agents for guinea pig ileum. Structure-activity studies with various N-formylated peptides suggest the presence of a specific receptor that resembles in specificity the formyl peptide receptor on leukocytes. A competitive antagonist of the formyl peptide receptor on leukocytes also inhibits formyl peptide-induced ileum contraction, whereas the antihistamine diphenhydramine is without effect. The contractile response caused by the synthetic N-formylated peptides differs from those induced by acetylcholine, histamine, and substance P. In particular, a latent period after treatment with the N-formyl peptides is seen before the onset of the response, and a sustained contractile response is not maintained. In addition, tachyphylaxis does occur, but complete recovery of activity is seen after a 20- to 30-min rest period. These observations suggest broad biological roles of prokaryotic signal peptides from bacteria as acute inflammatory mediators.

  10. CXCL17 is a major chemotactic factor for lung macrophages

    PubMed Central

    Burkhardt, Amanda M.; Maravillas-Montero, José L.; Carnevale, Christina D.; Vilches-Cisneros, Natalia; Flores, Juan P.; Hevezi, Peter A.; Zlotnik, Albert

    2014-01-01

    Chemokines are a superfamily of chemotactic cytokines that direct the movement of cells throughout the body under homeostatic and inflammatory conditions. The mucosal chemokine CXCL17 was the last ligand of this superfamily to be characterized. Several recent studies have provided greater insight into the basic biology of this chemokine and have implicated CXCL17 in several human diseases. We sought to better characterize CXCL17's activity in vivo. To this end, we analyzed its chemoattractant properties in vivo and characterized a Cxcl17-/- mouse. This mouse has a significantly reduced number of macrophages in their lungs compared to WT mice. Additionally, we observed a concurrent increase in a new population of macrophage-like cells that are F4/80+CDllcmid. These results indicate that CXCL17 is a novel macrophage chemoattractant that operates in mucosal tissues. Given the importance of macrophages in inflammation, these observations strongly suggest that CXCL17 is a major regulator of mucosal inflammatory responses. PMID:24973458

  11. Optimal Noise Filtering in the Chemotactic Response of Escherichia coli

    PubMed Central

    Andrews, Burton W; Yi, Tau-Mu; Iglesias, Pablo A

    2006-01-01

    Information-carrying signals in the real world are often obscured by noise. A challenge for any system is to filter the signal from the corrupting noise. This task is particularly acute for the signal transduction network that mediates bacterial chemotaxis, because the signals are subtle, the noise arising from stochastic fluctuations is substantial, and the system is effectively acting as a differentiator which amplifies noise. Here, we investigated the filtering properties of this biological system. Through simulation, we first show that the cutoff frequency has a dramatic effect on the chemotactic efficiency of the cell. Then, using a mathematical model to describe the signal, noise, and system, we formulated and solved an optimal filtering problem to determine the cutoff frequency that bests separates the low-frequency signal from the high-frequency noise. There was good agreement between the theory, simulations, and published experimental data. Finally, we propose that an elegant implementation of the optimal filter in combination with a differentiator can be achieved via an integral control system. This paper furnishes a simple quantitative framework for interpreting many of the key notions about bacterial chemotaxis, and, more generally, it highlights the constraints on biological systems imposed by noise. PMID:17112312

  12. Inactivation of chemotactic activity of C5a by the serratial 56-kilodalton protease.

    PubMed Central

    Oda, T; Kojima, Y; Akaike, T; Ijiri, S; Molla, A; Maeda, H

    1990-01-01

    The effects of the 56-kilodalton protease (56K protease) from Serratia marcescens on complement-derived chemotactic activity were examined. Fresh human serum was incubated with zymosan to produce C5a. This activated serum was then incubated with various concentrations of 56K protease, and the chemotactic activity of mouse peritoneal exudate polymorphonuclear leukocytes (PMN) and macrophages was evaluated. A significant dose-dependent decrease of chemotactic activity was observed after protease treatment. Furthermore, treatment of human recombinant C5a with 56K protease at a dose of 1.0 microgram/ml resulted in a complete loss of chemotactic activity. When the living bacteria of the virulent strain, which produced about 10 times more protease than did the less virulent strain, were injected intraperitoneally into mice, the magnitude of infiltration of polymorphonuclear leukocytes into the peritoneal cavity was much lower than that caused by the less virulent strain. Because complement-dependent chemotactic activity is an initial response to bacterial infection, these results suggest indirect pathogenic functions of serratial proteases that suppress chemotactic activity. PMID:1691142

  13. Chemotactic G protein-coupled receptors control cell migration by repressing autophagosome biogenesis.

    PubMed

    Coly, Pierre-Michaël; Perzo, Nicolas; Le Joncour, Vadim; Lecointre, Céline; Schouft, Marie-Thérèse; Desrues, Laurence; Tonon, Marie-Christine; Wurtz, Olivier; Gandolfo, Pierrick; Castel, Hélène; Morin, Fabrice

    2016-12-01

    Chemotactic migration is a fundamental behavior of cells and its regulation is particularly relevant in physiological processes such as organogenesis and angiogenesis, as well as in pathological processes such as tumor metastasis. The majority of chemotactic stimuli activate cell surface receptors that belong to the G protein-coupled receptor (GPCR) superfamily. Although the autophagy machinery has been shown to play a role in cell migration, its mode of regulation by chemotactic GPCRs remains largely unexplored. We found that ligand-induced activation of 2 chemotactic GPCRs, the chemokine receptor CXCR4 and the urotensin 2 receptor UTS2R, triggers a marked reduction in the biogenesis of autophagosomes, in both HEK-293 and U87 glioblastoma cells. Chemotactic GPCRs exert their anti-autophagic effects through the activation of CAPNs, which prevent the formation of pre-autophagosomal vesicles from the plasma membrane. We further demonstrated that CXCR4- or UTS2R-induced inhibition of autophagy favors the formation of adhesion complexes to the extracellular matrix and is required for chemotactic migration. Altogether, our data reveal a new link between GPCR signaling and the autophagy machinery, and may help to envisage therapeutic strategies in pathological processes such as cancer cell invasion.

  14. Character of cellulase activity in the guts of flagellate-free termites with different feeding habits.

    PubMed

    Li, Zhi-Qiang; Liu, Bing-Rong; Zeng, Wen-Hui; Xiao, Wei-Liang; Li, Qiu-Jian; Zhong, Jun-Hong

    2013-01-01

    Cellulose digestion in termites (Isoptera) is highly important for ecological reasons and applications in biofuel conversion. The speciose Termitidae family has lost flagellates in the hindgut and developed diverse feeding habits. To address the response of cellulase activity to the differentiation of feeding habits, a comparative study of the activity and distribution of composite cellulases, endo-β-1,4-glucanase, and β-glucosidase was performed in seven common flagellate-free termites with three feeding habits: the humus-feeding termites Sinocapritermes mushae (Oshima et Maki), Malaysiocapritermes zhangfengensis Zhu, Yang et Huang and Pericapritermes jiangtsekiangensis (Kemner); the fungus-growing termites Macrotermes barneyi Light and Odontotermes formosanus (Shiraki); and the wood-feeding termites Nasutitermes parvonasutus (Shiraki) and Havilanditermes orthonasus (Tsai et Chen). The results showed that in diverse feeding groups, the wood-feeding group had the highest total composite cellulase and endo-β-1,4-glucanase activities, while the fungus-growing group had the highest β-glucosidase activity. In terms of the distribution of cellulase activity in the alimentary canals, the cellulase activities in wood-feeding termites were concentrated in the midgut, but there was no significant difference between all gut segments in humus-feeding termites. As for the fungus-growing termites, the main site of composite cellulase activity was in the midgut. The endo-β-1,4-glucanase activity was restricted to the midgut, but the primary site of β-glucosidase activity was in the foregut and the midgut (Mac. barneyi). The functions of the gut segments apparently differentiated between feeding groups. The results suggest that the differentiation of feeding habits in flagellate-free termites was characterized by the distribution of cellulases in the gut rather than by variations in cellulase activity.

  15. Is there a relation between the distribution of heterotrophic flagellates and the zonation of a marine intertidal flat?

    NASA Astrophysics Data System (ADS)

    Tikhonenkov, D. V.; Burkovsky, I. V.; Mazei, Yu. A.

    2015-09-01

    The species distribution of heterotrophic flagellates has been investigated in accordance with the zonation of the White Sea silty-sandy intertidal flat. In Gryaznaya Bay of the Chernaya River Estuary (Kandalaksha Bay), 64 species and forms of flagellates have been identified. Three species ( Ploeotia tenuis, Salpingoeca tuba, and Thecamonas trahens) are newly recorded for the White Sea. The species diversity, abundance, and biomass of heterotrophic flagellates were the highest in the upper and lower littoral horizons, as compared to the middle littoral and transitional zones. The species composition and community structure of heterotrophic flagellates depend on the local combinations of salinity and Eh rather than on the littoral zone and related sediments and the type and amount of organic material. The heterotrophic flagellate community within the intertidal zone has been subdivided into three groups: 1) species preferring biotopes of higher salinity at lower and upper boundaries of the mid intertidal zone, 2) species tending to silty sediments of the upper intertidal zone with lower salinity and Eh, and 3) species preferring the well-aerated slightly silted sands of the lower intertidal zone.

  16. Inhibition of monocyte chemotactic protein-1 synthesis by statins.

    PubMed

    Romano, M; Diomede, L; Sironi, M; Massimiliano, L; Sottocorno, M; Polentarutti, N; Guglielmotti, A; Albani, D; Bruno, A; Fruscella, P; Salmona, M; Vecchi, A; Pinza, M; Mantovani, A

    2000-07-01

    The beneficial effects of statins on the reduction of cardiovascular events has been partly attributed to their anti-inflammatory properties. In the complex of the different pathogenetic events leading to atherosclerosis, recent data suggest a central role of monocyte chemotactic protein-1 (MCP-1), because mice knock-out for MCP-1 or its receptor CC-chemokine receptor 2 were considerably resistant to plaque formation. In this study we investigated the effect of different statins on in vitro and in vivo production of MCP-1. Lovastatin and simvastatin caused a dose-dependent inhibition of MCP-1 production in peripheral blood mononuclear cells exposed to lipopolysaccharide or inactivated Streptococcus hemoliticus and in human endothelial cells exposed to interleukin-1beta. The addition of mevalonate overrode the inhibitory effect of statins indicating that mevalonate-derived products are important for chemokine production. The in vivo anti-inflammatory effect of statins was investigated using the mouse air-pouch model of local inflammation. Lovastatin and pravastatin were orally administered to mice according to a treatment schedule that significantly inhibited the hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity without affecting total blood cholesterol. At the dose of 10 mg/kg, lovastatin and pravastatin reduced by approximately 50% the lipopolysaccharide-induced leukocytes recruitment and the exudate MCP-1 production. In conclusion, statins, by inhibiting mevalonate-derived products, reduced both in vitro and in vivo the production of chemokines involved in leukocyte migration, and this effect is unrelated to their cholesterol-lowering action.

  17. Speed-dependent chemotactic precision in marine bacteria

    PubMed Central

    Son, Kwangmin; Menolascina, Filippo; Stocker, Roman

    2016-01-01

    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

  18. Novel chemotactic-antigen DNA vaccine against cancer.

    PubMed

    Zhang, Shuren; Zhang, Youhui

    2008-04-01

    Dendritic cells play a pivotal role in immune induction. Dendritic cells perform antigen uptake, processing and presentation to T cells only when they are matured and in the functional state. In the development of a vaccine, it is of utmost importance to consider how to make dendritic cells' functions immunologically adequate. In this paper, we report the development of a series of antitumor DNA vaccines with similar structural framework, in which a gene encoding tumor-associated antigenic peptide is ligated upstream to the gene coding secondary lymphoid-tissue chemokine and downstream to the gene encoding the Fc portion of IgG (named chemotactic-antigen DNA vaccine [CADV]). CCR7(+) T, B, natural killer and dendritic cells can be attracted by secondary lymphoid-tissue chemokine, and Fc facilitates antigen uptake via Fc receptors expressed on dendritic cells. In a series of experiments in mice vaccinated by CADV with such tumor-associated antigenic specificities as HPV-16 E7, PSA-PSM-PAP, HER-2/neu, p53 and hTERT, CADV can attract immune cells to the vaccine inoculation site, remarkably inhibit tumor growth and extend survival time in tumor-bearing mice. The antitumor effect is more efficacious than that in mice treated with SLC-Ag or Ag-Fc hybrid gene. Tumor-associated antigenic-specific cytotoxic T lymphocytes can be induced by in vitro experiment in a human system. When combined with measures blocking the negative immune feedback circuits, the therapeutic effect of the vaccine can be further enhanced. Large-scale production of CADV is possible for clinical application.

  19. 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.

  20. A new flagellated dispersion stage in Paraphysoderma sedebokerense, a pathogen of Haematococcus pluvialis.

    PubMed

    Strittmatter, Martina; Guerra, Tiago; Silva, Joana; Gachon, Claire M M

    The blastocladialean fungus Paraphysoderma sedebokerense Boussiba, Zarka and James is a devastating pathogen of the commercially valuable green microalga Haematococcus pluvialis, a natural source of the carotenoid pigment astaxanthin. First identified in commercial Haematococcus cultivation facilities, P. sedebokerense is hypothesised to have a complex life cycle that switches between a vegetative and a resting phase depending on favourable or unfavourable growth conditions. Rather unusually for blastocladialean fungi, P. sedebokerense was described as lacking flagellated zoospores and only propagating via aplanosporic amoeboid cells. However, during repeated microscopic observation of P. sedebokerense cultivated in optimal conditions, we detected fast-swimming, transiently uniflagellated zoospores which rapidly transform into infectious amoeboid swarmers, the existence of which suggests a closer than previously thought relatedness of P. sedebokerense to its sister genera Physoderma and Urophlyctis. Additionally, we found some morphological and physiological differences between amoeboid swarmers and discuss hypotheses about their significance. These amoeboid and flagellated propagules are key to the dissemination of P. sedebokerense and are probably also the life stages most vulnerable to adverse environmental conditions. They are therefore a prime target for the development of disease management protocols in industrial cultivation facilities, a goal which requires a detailed understanding of their physiology.

  1. 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.

  2. Flagellar regeneration in the scaly green flagellate Tetraselmis striata (Prasinophyceae): regeneration kinetics and effect of inhibitors

    NASA Astrophysics Data System (ADS)

    Reize, I. B.; Melkonian, M.

    1987-06-01

    Flagellar regeneration after experimental amputation was studied in synchronized axenic cultures of the scaly green flagellate Tetraselmis striata (Prasinophyceae). After removal of flagella by mechanical shearing, 95% of the cells regrow all four flagella (incl. the scaly covering) to nearly full length with a linear velocity of 50 nm/min under standard conditions. Flagellar regeneration is independent of photosynthesis (no effect of DCMU; the same regeneration rate in the light or in the dark), but depends on de novo protein synthesis: cycloheximide at a low concentration (0.35 μM) blocks flagellar regeneration reversibly. No pool of flagellar precursors appears to be present throughout the flagellated phase of the cell cycle. A transient pool of flagellar precursors, sufficient to generate 2.5 μm of flagellar length, however, develops during flagellar regeneration. Tunicamycin (2 μg/ml) inhibits flagellar regeneration only after a second flagellar amputation, when flagella reach only one third the length of the control. Flagellar regeneration in T. striata differs considerably from that of Chlamydomonas reinhardtii and represents an excellent model system for the study of synchronous Golgi apparatus (GA) activation, and transport and exocytosis of GA-derived macromolecules (scales).

  3. 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

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

    PubMed

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

    2016-01-05

    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.

  5. Collective chemotactic dynamics in the presence of self-generated fluid flows.

    PubMed

    Lushi, Enkeleida; Goldstein, Raymond E; Shelley, Michael J

    2012-10-01

    In microswimmer suspensions locomotion necessarily generates fluid motion, and it is known that such flows can lead to collective behavior from unbiased swimming. We examine the complementary problem of how chemotaxis is affected by self-generated flows. A kinetic theory coupling run-and-tumble chemotaxis to the flows of collective swimming shows separate branches of chemotactic and hydrodynamic instabilities for isotropic suspensions, the first driving aggregation, the second producing increased orientational order in suspensions of "pushers" and maximal disorder in suspensions of "pullers." Nonlinear simulations show that hydrodynamic interactions can limit and modify chemotactically driven aggregation dynamics. In puller suspensions the dynamics form aggregates that are mutually repelling due to the nontrivial flows. In pusher suspensions chemotactic aggregation can lead to destabilizing flows that fragment the regions of aggregation.

  6. Collective chemotactic dynamics in the presence of self-generated fluid flows

    NASA Astrophysics Data System (ADS)

    Lushi, Enkeleida; Goldstein, Raymond E.; Shelley, Michael J.

    2012-10-01

    In microswimmer suspensions locomotion necessarily generates fluid motion, and it is known that such flows can lead to collective behavior from unbiased swimming. We examine the complementary problem of how chemotaxis is affected by self-generated flows. A kinetic theory coupling run-and-tumble chemotaxis to the flows of collective swimming shows separate branches of chemotactic and hydrodynamic instabilities for isotropic suspensions, the first driving aggregation, the second producing increased orientational order in suspensions of “pushers” and maximal disorder in suspensions of “pullers.” Nonlinear simulations show that hydrodynamic interactions can limit and modify chemotactically driven aggregation dynamics. In puller suspensions the dynamics form aggregates that are mutually repelling due to the nontrivial flows. In pusher suspensions chemotactic aggregation can lead to destabilizing flows that fragment the regions of aggregation.

  7. Bronchial epithelial cells release monocyte chemotactic activity in response to smoke and endotoxin

    SciTech Connect

    Koyama, S.; Rennard, S.I.; Leikauf, G.D.; Robbins, R.A. )

    1991-08-01

    An increase in mononuclear phagocytes occurs within the airways during airway inflammation. Bronchial epithelial cells could release monocyte chemotactic activity and contribute to this increase. To test this hypothesis, bovine bronchial epithelial cells were isolated and maintained in culture. Bronchial epithelial cell culture supernatant fluids were evaluated for monocyte chemotactic activity. Epithelial cell culture supernatant fluids attracted significantly greater numbers of monocytes compared to media alone and the number of monocytes attracted increased in a time dependent manner. Endotoxin and smoke extract induced a dose and time dependent release of monocyte chemotactic activity compared with cells cultured in media (52.5 {plus minus} 2.6 (endotoxin), 30.5 {plus minus} 2.3 (smoke) vs 20.5 {plus minus} 2.2 cells/high power field (HPF) p less than 0.001). The released activity was chemotactic by checkerboard analysis. Stimulation of the epithelial cells by opsonized zymosan, calcium ionophore (A23187), and PMA also resulted in an increase in monocyte chemotactic activity (p less than 0.01). Because the release of activity was blocked by the lipoxygenase inhibitors, nordihydroguaiaretic acid and diethycarbamazine, epithelial cell monolayers were cultured with 3 microCi (3H)arachidonic acid for 24 h and then exposed to A23187, PMA, or both stimuli, for 4, 8, and 24 h. Analysis of the released 3H activity was performed with reverse-phase HPLC and revealed that the major lipoxygenase product was leukotriene B4. These data suggest that monocytes may be recruited into airways in response to chemotactic factors released by bronchial epithelial cells.

  8. 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.

  9. Inheritance and diversification of symbiotic trichonymphid flagellates from a common ancestor of termites and the cockroach Cryptocercus.

    PubMed

    Ohkuma, Moriya; Noda, Satoko; Hongoh, Yuichi; Nalepa, Christine A; Inoue, Tetsushi

    2009-01-22

    Cryptocercus cockroaches and lower termites harbour obligate, diverse and unique symbiotic cellulolytic flagellates in their hindgut that are considered critical in the development of social behaviour in their hosts. However, there has been controversy concerning the origin of these symbiotic flagellates. Here, molecular sequences encoding small subunit rRNA and glyceraldehyde-3-phosphate dehydrogenase were identified in the symbiotic flagellates of the order Trichonymphida (phylum Parabasalia) in the gut of Cryptocercus punctulatus and compared phylogenetically to the corresponding species in termites. In each of the monophyletic lineages that represent family-level groups in Trichonymphida, the symbionts of Cryptocercus were robustly sister to those of termites. Together with the recent evidence for the sister-group relationship of the host insects, this first comprehensive study comparing symbiont molecular phylogeny strongly suggests that a set of symbiotic flagellates representative of extant diversity was already established in an ancestor common to Cryptocercus and termites, was vertically transmitted to their offspring, and subsequently became diversified to distinct levels, depending on both the host and the symbiont lineages.

  10. Colloidal silver nanoparticles/rhamnolipid (SNPRL) composite as novel chemotactic antibacterial agent.

    PubMed

    Bharali, P; Saikia, J P; Paul, S; Konwar, B K

    2013-10-01

    The antibacterial activity of silver nanoparticles and rhamnolipid are well known individually. In the present research, antibacterial and chemotactic activity due to colloidal silver nanoparticles (SNP), rhamnolipid (RL) and silver nanoparticles/rhamnolipid composite (SNPRL) were evaluated using Staphylococcus aureus (MTCC3160), Escherichia coli (MTCC40), Pseudomonas aeruginosa (MTCC8163) and Bacillus subtilis (MTCC441) as test strains. Further, the SNPRL nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The observation clearly indicates that SNPRL shows prominent antibacterial and chemotactic activity in comparison to all of its individual precursor components.

  11. Vertical distribution of the chloromonad flagellate Heterosigma carterae in columns: Implications for bloom development

    USGS Publications Warehouse

    Hershberger, P.K.; Rensel, J.E.; Matter, A.L.; Taub, F.B.

    1998-01-01

    Blooms of the marine flagellate Heterosigma carterae have been associated with catastrophic fish kills at mariculture facilities around the world. The precise cause(s) of the sudden appearance and disappearance of Heterosigma surface blooms has not been completely described or understood. Environmental data from prior studies of blooms indicate the presence of vertical stratification of the water column that is often induced by freshwater runoff. We report the relatively rapid concentration of Heterosigma cells at the surface of tubes shortly after the addition of distilled water to the surface. This phenomenon of cell concentration in surface waters may partially explain the sudden appearance of Heterosigma cells near the surface and subsequent disappearance when vertical stratification is lost due to turbulence or mixing. The results may lead to bloom mitigation techniques for net pen aquaculture.

  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. Platelet factors induce chemotactic migration of murine mammary adenocarcinoma cells with different metastatic capabilities.

    PubMed Central

    Sarach, M. A.; Rovasio, R. A.; Eynard, A. R.

    1993-01-01

    The chemotactic response of neoplastic cells (NC) induced by soluble platelet factors was investigated. NC suspensions isolated from murine mammary gland adenocarcinomas having different metastatic capabilities were incubated in Boyden's chambers and challenged with (1) 'Early Platelet Factors' (EP), obtained from the soluble fraction of recently collagen-activated human platelets, and (2) 'Late Platelet Factors' (LP), isolated after 24 hours incubation of the platelet aggregates. Chemotaxis was expressed as the distance travelled by NC through nitrocellulose filters. NC isolated from M3, the tumour line having the stronger metastatic potential, showed a significant chemotactic response towards LP factors, whereas NC from the M2 line exhibiting the lower metastatic behaviour, showed a chemotactic response towards EP factors. Both tumour cell lines lacked motion capability towards the well known chemoattractant peptide N-f-Met-Leu-Phe-Phe as well as to serum, plasma, collagen type I or culture medium. The different chemotactic response of both tumour lines when they were challenged by concentration gradients of factors released by early or late collagen-activated human platelets, confirm a relationship between platelet activity and metastatic capabilities and suggests that platelet chemoattractants might play a role in the metastatic dissemination of these mammary gland adenocarcinomas. Images Figure 1 PMID:8217786

  14. Characterization and reactivity of broiler chicken sera to selected recombinant Campylobacter jejuni chemotactic proteins.

    PubMed

    Yeh, Hung-Yueh; Hiett, Kelli L; Line, John E; Seal, Bruce S

    2014-05-01

    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 colonization and invasion in the host cells, proteins involved in chemotactic processes can be novel targets for vaccine development. In this communication, we report amplification, cloning and expression of the C. jejuni chemotactic proteins in an Escherichia coli expression system. A total of 15 chemotactic protein genes were successfully expressed. These recombinant proteins were confirmed by nucleotide sequencing, SDS-PAGE analysis and immunoblot analysis of six-His and hemagglutinin tags. Twelve recombinant chemotactic proteins were further tested whether they were antigenic using sera from broiler chickens older than 4 weeks. The immunoblot results show that each chicken serum reacted to a variety of the recombinant proteins, but all sera reacted to the Cjj0473 gene product (annotated as a methyl-accepting chemotaxis protein), suggesting that anti-Campylobacter antibodies may be prevalent in the poultry population. These antibody screening results provide a rationale for further evaluation of the Cjj0473 protein as a potential vaccine for broilers to improve human food safety.

  15. Presence of factors chemotactic for granulocytes in hypereosinophilic syndrome sera: relation with alterations in eosinophil migration.

    PubMed Central

    Gosset, P; Prin, L; Capron, M; Auriault, C; Tonnel, A B; Capron, A

    1986-01-01

    Recent work has underlined a structural and metabolic heterogeneity amongst blood eosinophils in various hypereosinophilic diseases. Little is known about the factors responsible for this variability. We have identified granulocyte chemotactic factors, termed GCFs in the sera of five patients with hypereosinophilic syndrome (HES). Sera from normal controls or from 20 patients with blood hypereosinophilia of various causes, but with little or no hypodense blood eosinophils, did not demonstrate any chemotactic activity. Two distinct GCFs were characterized, either by gel filtration or isoelectric focusing (molecular weights of 600 kD and 240 kD; pIs of approximately 5 and 7). These fractions are sensitive to proteolytic enzymes and to heating to 100 degrees C but not to 56 degrees C. The activity of GCFs has been tested towards neutrophils and eosinophils. The fractions of 240 kD and pI 7 appear more selective for the eosinophil lineage. Checkerboard analysis shows that such fractions are primarily chemotactic. In addition, hypodense eosinophils appear defective in random motility and chemotaxis towards chemotactic agents which are effective on normodense eosinophils. Moreover, preincubation of normodense eosinophils with HES sera rendered these cells unresponsive to very efficient chemotactic agents such as leukotriene B4 (LTB4) (decrease in migration of 91%; P less than 10(-3), formyl methionyl leucyl phenylalanyl (Fmlp) (decrease of 95%; P less than 10(-2)), HES sera (decrease of 91 to 93%). These findings suggest a process of deactivation of blood eosinophils with the possible retention within the circulation of activated hypodense eosinophils in HES. PMID:3780047

  16. Minimally modified low density lipoprotein induces monocyte chemotactic protein 1 in human endothelial cells and smooth muscle cells

    SciTech Connect

    Cushing, S.D.; Berliner, J.A.; Valente, A.J.; Territo, M.C.; Navab, M.; Parhami, F.; Gerrity, R.; Schwartz, C.J.; Fogelman, A.M.

    1990-07-01

    After exposure to low density lipoprotein (LDL) that had been minimally modified by oxidation (MM-LDL), human endothelial cells (EC) and smooth muscle cells (SMC) cultured separately or together produced 2- to 3-fold more monocyte chemotactic activity than did control cells or cells exposed to freshly isolated LDL. This increase in monocyte chemotactic activity was paralleled by increases in mRNA levels for a monocyte chemotactic protein 1 (MCP-1) that is constitutively produced by the human glioma U-105MG cell line. Antibody that had been prepared against cultured baboon smooth muscle cell chemotactic factor (anti-SMCF) did not inhibit monocyte migration induced by the potent bacterial chemotactic factor f-Met-Leu-Phe. However, anti-SMCF completely inhibited the monocyte chemotactic activity found in the media of U-105MG cells, EC, and SMC before and after exposure to MM-LDL. Moreover, monocyte migration into the subendothelial space of a coculture of EC and SMC that had been exposed to MM-LDL was completely inhibited by anti-SMCF. Anti-SMCF specifically immunoprecipitated 10-kDa and 12.5-kDa proteins from EC. Incorporation of (35S)methionine into the immunoprecipitated proteins paralleled the monocyte chemotactic activity found in the medium of MM-LDL stimulated EC and the levels of MCP-1 mRNA found in the EC. We conclude that SMCF is in fact MCP-1 and MCP-1 is induced by MM-LDL.

  17. Complement (C5)-derived chemotactic activity accounts for accumulation of polymorphonuclear leukocytes in cerebrospinal fluid of rabbits with pneumococcal meningitis.

    PubMed Central

    Ernst, J D; Hartiala, K T; Goldstein, I M; Sande, M A

    1984-01-01

    Experiments were performed to identify the chemoattractant for polymorphonuclear leukocytes that appears in the cerebrospinal fluid of rabbits with experimental pneumococcal meningitis. Meningitis was induced in anesthetized New Zealand white rabbits by injecting 10(4) cells of stationary-phase Streptococcus pneumoniae type III intracisternally. Before bacteria were injected, cerebrospinal fluid contained neither polymorphonuclear leukocytes nor chemotactic activity. Significant chemotactic activity for rabbit polymorphonuclear leukocytes was detected 12 h after inoculation with bacteria and was maximal after 18 to 20 h. Chemotactic activity appeared in cerebrospinal fluid while concentrations of pneumococci and total protein were increasing but before there was any accumulation of polymorphonuclear leukocytes. The chemotactic activity in cerebrospinal fluid was heat stable (56 degrees C for 30 min), eluted from Sephadex G-75 with a profile identical to that of the chemotactic activity in zymosan-activated rabbit serum, and was inhibited by treatment with antibodies to native human C5. In addition, preincubation of polymorphonuclear leukocytes with partially purified rabbit C5a selectively inhibited their subsequent chemotactic responses to cerebrospinal fluid. These data indicate that complement (C5)-derived chemotactic activity appears in cerebrospinal fluid during the course of experimental pneumococcal meningitis in rabbits and suggest that this activity accounts for the accumulation of polymorphonuclear leukocytes observed in this infection. PMID:6480117

  18. Ultrastructure and phylogenetic placement within Heterolobosea of the previously unclassified, extremely halophilic heterotrophic flagellate Pleurostomum flabellatum (Ruinen 1938).

    PubMed

    Park, Jong S; Simpson, Alastair G B; Lee, Won J; Cho, Byung C

    2007-07-01

    Although Pleurostomum was described almost a century ago, flagellates assigned to this taxon have been recorded only in very occasional faunistic studies of highly saline habitats, and their phylogenetic position has remained uncertain. We report the cultivation, ultrastructure, and phylogenetic relationships of Pleurostomum flabellatum isolated from a Korean saltern pond of 313 per thousand salinity. This isolate is biflagellated with a cytostomal groove, and is not distinguishable from previous accounts of P. flabellatum from saturated brines in India and Australia. Pleurostomum flabellatum shows ultrastructural features characteristic of many Heterolobosea: (1) a striated rhizoplast, (2) an absence of stacked Golgi bodies, (3) parallel basal bodies and flagella, and (4) a large number of peripheral microtubules supporting a rostrum. 18S rRNA gene phylogenies strongly confirm the affinities of P. flabellatum within Heterolobosea. Furthermore, the 18S rRNA gene of P. flabellatum has the heterolobosean-specific helix 17_1, and a group I intron in the same position as in Acrasis rosea. Within Heterolobosea, the 'amoeboflagellate' genera Naegleria and Willaertia were its closest relatives with high bootstrap support and posterior probability. P. flabellatum was observed only as a flagellate, and never as an amoeba. Since light microscopy and electron microscopy observations indicate that P. flabellatum flagellates are capable both of feeding and division, there might be no amoeba stage. Being morphologically distinct from its closest relatives and phylogenetically distant from other flagellate-only Heterolobosea, P. flabellatum cannot be moved into any previously described heterolobosean genus. Instead, we move Pleurostomum into Heterolobosea, and assign as the type species Pleurostomum salinum Namyslowski 1913, a species that closely resembles P. flabellatum. The optimal temperature for growth of P. flabellatum is 40 degrees C. Interestingly, P. flabellatum grows

  19. Morphology and phylogeny of a new wall-less freshwater volvocalean flagellate, Hapalochloris nozakii gen. et sp. nov. (Volvocales, Chlorophyceae).

    PubMed

    Nakada, Takashi; Tomita, Masaru

    2016-10-21

    New strains of a wall-less unicellular volvocalean flagellate were isolated from a freshwater environment in Japan. Observations of the alga, described here as Hapalochloris nozakii Nakada, gen. et sp. nov., were made using light, fluorescence, and electron microscopy. Each vegetative cell had two flagella, four contractile vacuoles, and a spirally furrowed cup-shaped chloroplast with an axial pyrenoid, and mitochondria located in the furrows. Based on the morphology, H. nozakii was distinguished from other known wall-less volvocalean flagellates. Under electron microscopy, fibrous material, instead of a cell wall and dense cortical microtubules, was observed outside and inside the cell membrane, respectively. Based on the phylogenetic analyses of 18S rRNA gene sequences, H. nozakii was found to be closely related to Asterococcus, Oogamochlamys, Rhysamphichloris, and "Dunaliella" lateralis and was separated from other known wall-less flagellate volvocaleans, indicating independent secondary loss of the cell wall in H. nozakii. In the combined 18S rRNA and chloroplast gene tree, H. nozakii was sister to Lobochlamys.

  20. The chemotactic properties of porcine seminal components toward neutrophils in vitro.

    PubMed

    Rozeboom, K J; Troedsson, M H; Rocha, G R; Crabo, B G

    2001-04-01

    Our objectives were to investigate the mechanisms of postbreeding inflammation in swine by examining the chemotactic properties of polymorphonuclear neutrophilic granulocytes (PMN) and of various populations of spermatozoa and seminal plasma. Epididymal spermatozoa from two boars obtained under sterile conditions, washed ejaculated spermatozoa from two boars, and pooled seminal plasma from eight boars of known fertility were examined for chemotaxis to PMN. The chemotaxis of blood-derived PMN in response to sperm and seminal plasma was evaluated and expressed as a percentage of a positive control (lipopolysaccharide-activated blood plasma). The mean chemotactic effect of washed sperm alone (4.4+/-0.04) and of epididymal sperm alone (3.4+/-0.06) was not different from that of the negative controls (3.1+/-0.05) of McCoy's medium with 10% heat-inactivated fetal calf serum. A marked chemotactic effect was detected when washed ejaculated and epididymal sperm were incubated with blood plasma, compared with blood plasma without spermatozoa (P < 0.001). Washed sperm in blood plasma (86.2+/-5.6) and epididymal sperm in blood plasma (83.9+/-7.7) were different from blood plasma alone (11.2+/-1.5), but no differences were detected between the two populations of sperm. This effect, however, was not completely inhibited by heat inactivation of the blood plasma. The chemotactic response of washed ejaculated and epididymal spermatozoa incubated in lipopolysaccharide-treated, heat-inactivated blood plasma were greater than that of the negative control (P < 0.05). Polymorphonuclear neutrophilic granulocyte migration toward seminal plasma was similar to the negative control (4.0+/-0.04 vs 3.1+/-0.05). It seems that porcine epididymal sperm and ejaculated sperm activate chemotactic components in porcine blood plasma and heat-inactivated blood plasma, suggesting that, at least partially, a heat-stable (noncomplement) blood plasma component may be involved in sperm-induced PMN

  1. Identification of putative miRNAs from the deep-branching unicellular flagellates.

    PubMed

    Huang, Po-Jung; Lin, Wei-Chen; Chen, Shih-Chieh; Lin, Yong-Han; Sun, Chin-Hung; Lyu, Ping-Chiang; Tang, Petrus

    2012-02-01

    MicroRNAs (miRNAs) are a class of extensively studied RNAi-associated small RNAs that play a critical role in eukaryotic gene regulation. However, knowledge on the miRNA and its regulation in unicellular eukaryotes is very limited. In order to obtain a better understanding on the origin of miRNA regulation system, we used deep-sequencing technology to investigate the miRNA expression pattern in four deep-branching unicellular flagellates: Giardia lamblia, Trichomonas vaginalis, Tritrichomonas foetus, and Pentatrichomonas hominis. In addition to the known miRNAs that have been described in G. lamblia and T. vaginalis, we identified 14 ancient animal miRNA families and 13 plant-specific families. Bioinformatics analysis also identified four novel miRNA candidates with reliable precursor structures derived from mature tRNAs. Our results indicated that miRNAs are likely to be a general feature for gene regulation throughout unicellular and multicellular eukaryotes and some of them may derive from unconventional ncRNAs such as snoRNA and tRNA.

  2. 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.

  3. Indications for acceleration-dependent changes of membrane potential in the flagellate Euglena gracilis.

    PubMed

    Richter, P R; Schuster, M; Meyer, I; Lebert, M; Häder, D-P

    2006-12-01

    The effects of the calcium sequester EGTA on gravitactic orientation and membrane potential changes in the unicellular flagellate Euglena gracilis were investigated during a recent parabolic-flight experiment aboard of an Airbus A300. In the course of a flight parabola, an acceleration profile is achieved which yields subsequently about 20 s of hypergravity (1.8 g(n)), about 20 s of microgravity, and another 20 s of hypergravity phases. The movement behavior of the cells was investigated with real-time, computer-based image analysis. Membrane potential changes were detected with a newly developed photometer which measures absorption changes of the membrane potential-sensitive probe oxonol VI. To test whether the data obtained by the oxonol device were reliable, the signal of non-oxonol-labelled cells was recorded. In these samples, no absorption shift was detected. Changes of the oxonol VI signals indicate that the cells depolarize during acceleration (very obvious in the step from microgravity to hypergravity) and slightly hyperpolarize in microgravity, which can possibly be explained with the action of Ca-ATPases. These signals (mainly the depolarization) were significantly suppressed in the presence of EGTA (5 mM). Gravitaxis in parallel was also inhibited after addition of EGTA. Initially, negative gravitaxis was inverted into a positive one. Later, gravitaxis was almost undetectable.

  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. 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.

  6. 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.

  7. Physiological parameters of gravitaxis in the flagellate Euglena gracilis obtained during a parabolic flight campaign.

    PubMed

    Richter, Peter R; Schuster, Martin; Wagner, Helmut; Lebert, Michael; Hader, Donat-P

    2002-02-01

    The unicellular freshwater flagellate Euglena gracilis and its close relative Astasia longa show a pronounced negative gravitaxis. Previous experiments revealed that gravitaxis is most likely mediated by an active physiological mechanism in which changes of the internal calcium concentration and the membrane potential play an important role. In a recent parabolic flight experiment on board an aircraft (ESA 29th parabolic flight campaign), changes of graviorientation, membrane potential and the cytosolic calcium concentration upon changes of the acceleration (between 1 x g(n), 1.8 x g(n), microgravity) were monitored by image analysis and photometric methods using Oxonol VI (membrane potential) and Calcium Crimson (cytosolic calcium concentration). The parabolic flight maneuvers performed by the aircraft resulted in transient phases of 1.8 x g(n) (about 20 s), microgravity (about 22 s) followed by 1.8 x g(n) (about 20 s). A transient increase in the intracellular calcium concentration was detected from lower to higher accelerations (1 x g(n) to 1.8 x g(n) or microgravity to 1.8 x g(n)). Oxonol VI-labeled cells showed a signal, which indicates a depolarization during the transition from 1 x g(n) to 1.8 x g(n), a weak repolarization in microgravity followed by a rapid repolarization in the subsequent 1 x g(n) phase. The results show good coincidence with observations of recent terrestrial and space experiments.

  8. Ultrastructure of Amastigomonas bermudensis ATCC 50234 sp. nov.: A new heterotrophic marine flagellate.

    PubMed

    Molina, F I; Nerad, T A

    1991-11-29

    The ultrastructure of a new marine heterotrophic flagellate is described. The cell is dorso-ventrally flattened and displays a steady gliding forward movement. A longitudinal groove whose lips are appressed to the substrate runs along the ventral aspect of the cell. The two heterodynamic flagella originate from the proximal end of a cytoplasmic sheath that enfolds most of the length of the anterior flagellum. The lips of this sheath are continuous with the margins of the ventral groove. The posterior trailing flagellum is held closely appressed to the cell body on one side of the ventral groove. Three bands of microtubules extend posteriorly into the cell body and are associated with the kinetosomes. The part of the surface membrane extending over the cell's dorsal and lateral aspect is five-layered, giving the semblance of two fused cell membranes. There is a fibrillar layer underneath these membranes. There is also a fibrous network whose arrays are oriented in different directions within the cytoplasm. Mitochondria have tubular cristae. Based on a comparison with previously described species of Amastigomonas, we establish the species, A. bermudensis n.sp. We further conclude that Thecamonas is a junior synonym of Amastigomonas and move the three nominal species to the latter genus.

  9. Chemotactic sensing towards ambient and secreted attractant drives collective behaviour of E. coli.

    PubMed

    Curk, Tine; Marenduzzo, Davide; Dobnikar, Jure

    2013-01-01

    We simulate the dynamics of a suspension of bacterial swimmers, which chemotactically sense gradients in either ambient or self-secreted attractants (e.g. nutrient or aspartate respectively), or in both. Unlike previous mean field models based on a set of continuum partial differential equations, our model resolves single swimmers and therefore incorporates stochasticity and effects due to fluctuations in the bacterial density field. The algorithm we use is simple enough that we can follow the evolution of colonies of up to over a million bacteria for timescales relevant to pattern formation for E. coli growing in semisolid medium such as agar, or in confined geometries. Our results confirm previous mean field results that the patterns observed experimentally can be reproduced with a model incorporating chemoattractant secretion, chemotaxis (towards gradients in the chemoattractant field), and bacterial reproduction. They also suggest that further experiments with bacterial strains chemotactically moving up both nutrient and secreted attractant field may yield yet more dynamical patterns.

  10. Chemotactic movement in sperm of the oogamous brown algae, Saccharina japonica and Fucus distichus.

    PubMed

    Kinoshita, Nana; Nagasato, Chikako; Motomura, Taizo

    2017-01-01

    In oogamous species of brown algae such as Saccharina japonica and Fucus distichus, the sperm possess an unusual long posterior flagellum, which oscillates actively and produces a propulsive force during swimming. In this study, we quantitatively analyzed the effect of chemotactic responses on sperm swimming and flagellar waveforms by high-speed video recordings. We found that the thigmotactic response to the chemo-attractant was not enhanced during chemotactic swimming and that the swimming velocity of sperm did not decrease. As concentration of the chemo-attractant decreased, the sperm performed drastic U-turn movements, which was caused by a rapid and large bend of the posterior flagellum. Unilateral bending of the posterior flagellum when sensing a decrease in the concentration of the chemo-attractant may be a common response in male gametes during fertilization of brown algae both oogamous and isogamous species.

  11. 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

  12. Chemotactic selection with insulin, di-iodotyrosine and histamine alters the phagocytotic responsiveness of Tetrahymena.

    PubMed

    Schiess, N; Csaba, G; Kohidai, L

    2001-04-01

    Chemotactic selection is a method by which populations of cells exposed to ligands can be isolated and subsequently cultivated. We used Tetrahymena pyriformis GL cultures selected by chemotactic selection to insulin (10 nM), histamine (0.1 nM) and di-iodotyrosine (T2, 10 nM) to study the phagocytotic capacity under the induction of selector hormones. Our results show a long-lasting link between chemotactically selected cultures and phagocytotic activity. Cells selected to histamine produced the highest phagocytotic activity upon a second exposure to the selector hormone. T2 selection was also strongly effective, however, the phagocytosis stimulation was not specific to the hormone given later. Insulin selected sub-populations had different phagocytotic responses to the control substance itself, whereas histamine selected sub-populations seem to be heterogeneous in the phagocytotic response to histamine. For insulin, the increased endocytotic or metabolic activity was demonstrated by the lack of non-phagocytotic cells. These experiments call attention to the evolutionary role of selection in the later developing receptor-hormone relationship.

  13. Chemotactic activity of Helicobacter pylori sonicate for human polymorphonuclear leucocytes and monocytes.

    PubMed Central

    Nielsen, H; Andersen, L P

    1992-01-01

    The immunopathology of Helicobacter pylori associated active chronic gastritis, which is characterised by predominance of polymorphonuclear leucocyte infiltration, is largely unknown. To evaluate the role of bacterial components as inflammatory mediators ultracentrifuged sonicated preparations were made of clinical isolates of Helicobacter pylori. The crude sonicates were shown to exhibit chemotactic activity for human polymorphonuclear leucocytes and blood monocytes in a concentration dependent fashion. The potency was comparable with previously described bacterial derived cytotaxins. The cytotaxin(s) was non-dialysable and completely destroyed by proteinase. Heat treatment did not decrease the chemotactic activity, but in sonicate subjected to 100 degrees C for 15 minutes all activity disappeared after dialysis suggesting the breakdown of a larger protein to small fragments that are still biological active. By ammonium sulphate precipitation at increasing concentrations the cytotaxin(s) was selectively found in 10% ammonium sulphate saturation, and by further molecular gel separation the chemotactic activity was found in the molecular size range from 25 to 35 kDa. The demonstration of a polymorphonuclear leucocyte and monocyte cytotaxin from Helicobacter pylori sonicate may help in understanding the mucosal immune response in gastric inflammatory diseases. PMID:1624151

  14. MACROPHAGE MIGRATION INHIBITORY FACTOR REGULATES NEUTROPHIL CHEMOTACTIC RESPONSES IN INFLAMMATORY ARTHRITIS

    PubMed Central

    Santos, Leilani L.; Fan, Huapeng; Hall, Pam; Ngo, Devi; Mackay, Charles R.; Fingerle-Rowson, Gunter; Bucala, Richard; Hickey, Michael J.; Morand, Eric F.

    2010-01-01

    Objectives Macrophage migration inhibitory factor (MIF) facilitates multiple aspects of inflammatory arthritis, the pathogenesis of which is significantly contributed to by neutrophils. The effects of MIF on neutrophil recruitment are unknown. We investigated the contribution of MIF to the regulation of neutrophil chemotactic responses. Methods K/BxN serum transfer arthritis was induced in wild-type (WT), MIF -/-, and MCP1 (CCL2)-deficient mice, and in WT mice treated with anti-KC (CXCL1) mAb. In vivo leukocyte trafficking was examined using intravital microscopy, and in vitro neutrophil function was examined using migration chambers and MAP kinase activation. Results K/BxN serum transfer arthritis was markedly attenuated in MIF-/- mice, with reductions in clinical and histological severity as well as synovial expression of KC and IL-1. Arthritis was also reduced by anti-KC antibody treatment, but not in MCP-1-deficient mice. In vivo neutrophil recruitment responses to KC were reduced in MIF-/- mice. Similarly, MIF-/-neutrophils exhibited reduced in vitro chemotactic responses to KC, despite unaltered chemokine receptor expression. Reduced chemotactic responses in MIF-/- neutrophils were associated with reduced phosphorylation of p38 and ERK MAP kinases. Conclusion These data suggest MIF promotes neutrophil trafficking in inflammatory arthritis via facilitation of chemokine-induced migratory responses and MAP kinase activation. Therapeutic MIF inhibition could limit synovial neutrophil recruitment. PMID:21452319

  15. 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.

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

    PubMed

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

    2016-04-14

    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.

  17. 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.

  18. 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.

  19. Isolation and characterization of flagellates from rodents and canids in Masinga, Machakos District, Kenya.

    PubMed

    Githure, John I.; Anjili, Christopher O.; Ngumbi, Philip M.; Mwanyumba, Panuel M.; Lugalia, Reuben; Koech, Davy K.; Kinoti, George K.

    1995-11-01

    A total of 728 animals comprising of 633 rodents and 95 canids were examined for leishmanial parasites. Flagellates were isolated from 67 out of 111 (60.4%) Acomys subspinosus (spiny mouse), 12 out of 143 (8.4% ) Mastomys natalensis (multimammate rat), 2 out of 50 (4.0%) Lemniscomys striatus (striped mouse), 2 out of 6 (33.3%) Herpestes sanguineus (slender mongoose), 1 of 1 Helogale parvula (dwarf mongoose) and 1 out of 84 Canis familiaris (domestic dog). All isolates were characterized by Isoenzyme analysis using nine enzymes, namely, malate dehydrogenase (MDH), phosphoglucomutase (PGM), glucose phosphate isomerase (GPI), isocitrate dehydrogenase (ICD), nucleoside hydrolase (NH), glucose 6-phosphate dehydrogenase (G6PD), malic enzyme (ME), 6-phosphogluconate dehydrogenase (GPGD) and mannose phosphate isomerase (MPI). Enzyme profiles of these isolates were compared with those of five WHO Leishmania reference strains and five well characterized rodent trypanosomes of the subgenus Herpetosoma. The profiles of the isolates were found to be different from those of the Leishmania and Trypanosoma reference strains but the parasites were morphologically similar to rodent trypanosomes. These results suggest that Leishmania parasites were not among the isolates. The enzymes profiles of the three mongoose isolates were identical but differed from profiles of isolates from rodents and dog. This is the first time in Kenya that a high prevalence of nonpathogenic trypanosomes is reported in rodents and canids. From the epidemiological point of view, these trypanosomes must be differentiated from the pathogenic species of trypanosomes and Leishmania that infect man and other animals. The results of this study suggest that rodents do not seem to play a role as reservoirs of Leishmania parasites in Masinga Location, Kenya.

  20. Identification criteria of the rare multi-flagellate Lophomonas blattarum: comparison of different staining techniques.

    PubMed

    Alam-Eldin, Yosra Hussein; Abdulaziz, Amany Mamdouh

    2015-09-01

    Bronchopulmonary lophomoniasis (BPL) is an emerging disease of potential importance. BPL is presented by non-specific clinical picture and is usually accompanied by immunosuppression. Culture of Lophomonas blattarum is difficult and its molecular diagnosis has not yet been developed. Therefore, microscopic examination of respiratory samples, e.g., bronchoalveolar lavage (BAL) or sputum, is the mainstay of BPL diagnosis. Creola bodies and ciliocytophthoria are two forms of bronchial cells which occur in chest diseases with non-specific clinical picture like that of BPL. Both forms could be misrecognized as multi-flagellates because of their motile cilia in the wet mounts and due to shape variability of L. blattarum in stained smears. The aim of the study is to compare different staining techniques for visualizing L. blattarum to improve the recognition and diagnosis of BPL, to distinguish respiratory epithelial cells from L. blattarum and to decide which stain is recommended in suspected cases of BPL. BAL samples from patients which contain L. blattarum, creola bodies, and ciliocytophthoria were collected then wet mounts were examined. The BAL samples were also stained by Papanicolaou (PAP), Giemsa, hematoxylin and eosin (H & E), trichrome, Gram, and Diff-Quik (DQ) stains. The different staining techniques were compared regarding the stain quality. In wet mounts, the ciliary movement was coordinate and synchronous while the flagellar movement was wavy and leaded to active swimming of L. blattarum. In stained slides, bronchial cells were characterized by the presence of basal nucleus and the terminal bar from which the cilia arise. Trichrome was the best stain in demonstration of cellular details of L. blattarum. H & E, PAP, and Giemsa stains showed good quality of stains. Gram and DQ stains showed only pale hues of L. blattarum. We recommended adding Wheatley's trichrome staining to the differential diagnosis workup of cases of non-specific chest infections

  1. Live-cell super-resolution imaging of intrinsically fast moving flagellates

    NASA Astrophysics Data System (ADS)

    Glogger, M.; Stichler, S.; Subota, I.; Bertlein, S.; Spindler, M.-C.; Teßmar, J.; Groll, J.; Engstler, M.; Fenz, S. F.

    2017-02-01

    Recent developments in super-resolution microscopy make it possible to resolve structures in biological cells at a spatial resolution of a few nm and observe dynamical processes with a temporal resolution of ms to μs. However, the optimal structural resolution requires repeated illumination cycles and is thus limited to chemically fixed cells. For live cell applications substantial improvement over classical Abbe-limited imaging can already be obtained in adherent or slow moving cells. Nonetheless, a large group of cells are fast moving and thus could not yet be addressed with live cell super-resolution microscopy. These include flagellate pathogens like African trypanosomes, the causative agents of sleeping sickness in humans and nagana in livestock. Here, we present an embedding method based on a in situ forming cytocompatible UV-crosslinked hydrogel. The fast cross-linking hydrogel immobilizes trypanosomes efficiently to allow microscopy on the nanoscale. We characterized both the trypanosomes and the hydrogel with respect to their autofluorescence properties and found them suitable for single-molecule fluorescence microscopy (SMFM). As a proof of principle, SMFM was applied to super-resolve a structure inside the living trypanosome. We present an image of a flagellar axoneme component recorded by using the intrinsic blinking behavior of eYFP. , which features invited work from the best early-career researchers working within the scope of J Phys D. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Susanne Fenz was selected by the Editorial Board of J Phys D as an Emerging Talent/Leader.

  2. RANTES and Chemotactic Activity in Synovial Fluids From Patients With Rheumatoid Arthritis and Osteoarthritis

    PubMed Central

    Stanczyk, Joanna; Kowalski, Marek L.; Grzegorczyk, Janina; Szkudlinska, Barbara; Jarzebska, Marzanna; Marciniak, Marek; Synder, Marek

    2005-01-01

    A massive accumulation of inflammatory cells in synovial tissues is a major pathological feature of rheumatoid arthritis (RA). Neutrophiles dominate synovial fluid while rheumatoid synovium is infiltrated with mononuclear cells. Mechanisms regulating influx of particular subpopulations of leukocytes into articular cavity and synovium compartment are not completely defined. An increasing amount of data supports a crucial role of a C-C chemokine RANTES in the RA pathogenesis. Our objective is to evaluate chemotactic activity for neutrophils (NCA), lymphocytes (LCA), and monocytes (MoCA) in SFs obtained from patients with RA and osteoarthritis (OA). We also aimed to characterise the relation between chemotactic activity, RANTES, and percentage distribution of leukocytes in SF. SFs from 11 patients with RA and 6 with OA were included in the study. Modified microchamber Boyden method was employed to assess chemotactic activity. Cytological and biochemical analysis of SF was performed. RANTES was measured with ELISA. Rheumatoid SFs were rich in cells with predominance of neutrophiles while osteoarthritic fluids were lymphocytic. RA SFs were also characterised by increased lactoferrin level. Both NCA and LCA were higher in SF from patients with RA (62 ± 12 and 24 ± 6 cells/HPF, resp) as compared to patients with OA (23 ± 6; P < .05 and 6 ± 2 cells/HPF; P < 0.05). The chemoattractive effect of RA SF was more pronounced on neutrophiles than on lymphocytes. RA SF expressed high RANTES levels (145 ± 36 pg/mL), while OA SF was characterised by only trace amount of this chemokine (2 ± 1 pg/mL). We found positive correlation of RANTES with chemotactic activity for mononuclear cells (LCA+MoCA; R = 0.61; P < .05). Surprisingly, RANTES correlated also positively with neutrophiles number (R = 0.77; P < 0.001). Rheumatoid SF possesses strong chemotactic potency for leukocytes. RANTES is overexpressed in RA SF and is a potential mediator influencing intensity and composition

  3. In Vivo Crevicular Leukocyte Response to a Chemotactic Challenge: Inhibition by Experimental Diabetes

    PubMed Central

    Golub, Lorne M.; Nicoll, Gregg A.; Iacono, Vincent J.; Ramamurthy, Nungavaram S.

    1982-01-01

    Diabetes in rats inhibits the migration of neutrophils into the healing gingival crevice, an effect associated with impaired in vitro neutrophil chemotactic activity. We recently described the in vivo response of human and rat crevicular neutrophils to a chemotactic challenge and used this assay in the present study on streptozotocin-induced diabetic rats. Optimal concentrations of two chemotactic agents, casein (0.2 μl, 2 mg/ml) or N-formylmethionylleucylphenylalanine (0.2 μl, 10−4 M), were placed into the gingival crevices of control and diabetic rats (time zero) after the resting neutrophil count was measured. After a 15-min delay, the neutrophil counts and gingival crevicular fluid flow were assessed every 5 min for another 0.5 h. The control rats (n = 14) showed an increase in neutrophil counts which reached maximum levels 30 min after the N-formylmethionylleucylphenylalanine challenge (“peak” neutrophil response) and decreased dramatically 5 min later. Diabetes of 4 days (n = 4), 14 days (n = 8), and 20 days (n = 5) duration reduced the peak neutrophil response 45, 66, and 71%, respectively. Casein produced the same response as N-formylmethionylleucylphenylalanine in control rats. Uncontrolled diabetes of 20 days duration reduced the peak neutrophil response to casein by 83%; diabetics administered insulin on a daily basis showed a reduction of only 34%. The pattern of change in gingival crevicular fluid flow in response to chemoattractants paralleled the neutrophil response. The chemotactic activity of peritoneal neutrophils was assessed in vitro with the agarose gel technique and was found to be correlated (r = 0.84; P < 0.01) with the in vivo chemotactic response in the same rats. If the same in vivo defect is observed in humans with diabetes (or with other systemic diseases associated with leukocyte dysfunction), this test could be useful diagnostically to rapidly assess neutrophil chemotaxis in lieu of in vitro assays and to identify patients who

  4. A common soil flagellate (Cercomonas sp.) grows slowly when feeding on the bacterium Rhodococcus fascians in isolation, but does not discriminate against it in a mixed culture with Sphingopyxis witflariensis.

    PubMed

    Lekfeldt, Jonas Duus Stevens; Rønn, Regin

    2008-07-01

    Flagellates are very important predators on bacteria in soil. Because of their high growth rates, flagellate populations respond rapidly to changes in bacterial numbers. Previous results indicate that actinobacteria are generally less suitable than proteobacteria as food for flagellates. In this study, we investigated the growth of the flagellate Cercomonas sp. (ATCC 50334) on each of the two bacteria Sphingopyxis witflariensis (Alphaproteobacteria) and Rhodococcus fascians (actinobacteria) separately and in combination. The growth rate of the flagellate was lower and the lag phase was longer when fed with R. fascians than when fed with S. witflariensis. This supports our initial hypothesis that the actinobacterium is less suitable as food than the alphaproteobacterium. However, after longer periods of growth the peak abundance of flagellates was higher on R. fascians, indicating that the food quality of bacterial prey depends on the time perspective of the flagellate-bacterial interaction. There was no evidence that the flagellates selected against the actinobacterium when feeding in mixed cultures of the two bacteria. Experiments where flagellates were fed with washed bacterial cells or with bacteria growing with different substrate concentrations suggested that the low food quality of R. fascians is related both to the intrinsic cell properties and to the extracellular metabolites.

  5. Combined influence of quartz dust, ozone and NO2 on chemotactic mobility, release of chemotactic factors and other cytokines by macrophages in vitro.

    PubMed

    Polzer, G; Lind, I; Mosbach, M; Schmidt, A; Seidel, A

    1994-06-01

    In this study the single as well as combined effects of quartz, ozone and nitrogen dioxide (NO2) on some immunofunctions of bovine alveolar macrophages (BAM) were investigated. After incubation with 10 micrograms/ml of particles the chemotactic response of BAM is increased nonspecifically, whereas after incubation with 100 micrograms/ml of quartz chemotaxis is specifically decreased. In addition, quartz induces tumor necrosis factor alpha (TNF-alpha) and chemokines to be released dependent on the concentration. Ozone by itself is also a very potent inducer of the release of chemokines and TNF-alpha, but in combination with ozone, quartz has not more than an additive effect. NO2 alone suppresses drastically the release of TNF-alpha. The results show that quartz, ozone and NO2 alter some immunofunctions of BAM and that by combining toxic particles such as quartz with these gases, additive but not synergistic effects might be expected.

  6. Flagellate infections of Brazilian sand flies (Diptera: Psychodidae): isolation in vitro and biochemical identification of Endotrypanum and Leishmania.

    PubMed

    Arias, J R; Miles, M A; Naiff, R D; Povoa, M M; de Freitas, R A; Biancardi, C B; Castellon, E G

    1985-11-01

    Flagellate infections were found in 1,063 of 18,895 sand flies collected in the states of Amazonas, Pará, Rondonia and Acre, Brazil. Infection rates were 13.4% (species group Shannoni); 7.5% (subgenus Nyssomyia); 6.7% (subgenus Lutzomyia series Cruciata); 0.5% (genus Psychodopygus) and 3.1% for other sand flies (various subgenera). Leishmania braziliensis guyanensis and L. mexicana amazonensis were isolated, respectively, from the known vectors, Lutzomyia umbratilis and L. flaviscutellata. Single stocks of L. braziliensis-like and L. mexicana-like organisms were isolated, respectively, from L. whitmani and L. yuilli. Thirty-eight flagellate stocks, isolated by direct culture from sand flies were characterized in detail by morphology in culture, behavior in hamsters and mice and by enzyme profiles. Sixteen stocks from Lutzomyia sp. (Shannoni group) were identified as Endotrypanum schaudinni; 8 stocks from Lutzomyia sp. (Shannoni group) were identified as Endotrypanum sp.; 7 stocks from Psychodopygus ayrozai and P. paraensis were identified as Leishmania sp. previously isolated from the armadillo, Dasypus novemcinctus; 2 stocks of Trypanosoma rangeli were isolated from recently fed Lutzomyia sp. (Shannoni group) sand flies; the remaining 5 stocks from L. umbratilis and L. yuilli could not be identified. Observations suggested that Shannoni group sand flies were the natural vectors of Endotrypanum. Leishmania sp. infections in the man-biting flies P. ayrozai and P. paraensis were restricted to the midgut and associated with recent bloodmeals. Unidentified flagellates in L. umbratilis and L. yuilli were distributed throughout the digestive tract with no trace of bloodmeals.

  7. EST analysis of the scaly green flagellate Mesostigma viride (Streptophyta): Implications for the evolution of green plants (Viridiplantae)

    PubMed Central

    Simon, Andreas; Glöckner, Gernot; Felder, Marius; Melkonian, Michael; Becker, Burkhard

    2006-01-01

    Background The Viridiplantae (land plants and green algae) consist of two monophyletic lineages, the Chlorophyta and the Streptophyta. The Streptophyta include all embryophytes and a small but diverse group of freshwater algae traditionally known as the Charophyceae (e.g. Charales, Coleochaete and the Zygnematales). The only flagellate currently included in the Streptophyta is Mesostigma viride Lauterborn. To gain insight into the genome evolution in streptophytes, we have sequenced 10,395 ESTs from Mesostigma representing 3,300 independent contigs and compared the ESTs of Mesostigma with available plant genomes (Arabidopsis, Oryza, Chlamydomonas), with ESTs from the bryophyte Physcomitrella, the genome of the rhodophyte Cyanidioschyzon, the ESTs from the rhodophyte Porphyra, and the genome of the diatom Thalassiosira. Results The number of expressed genes shared by Mesostigma with the embryophytes (90.3 % of the expressed genes showing similarity to known proteins) is higher than with Chlamydomonas (76.1 %). In general, cytosolic metabolic pathways, and proteins involved in vesicular transport, transcription, regulation, DNA-structure and replication, cell cycle control, and RNA-metabolism are more conserved between Mesostigma and the embryophytes than between Mesostigma and Chlamydomonas. However, plastidic and mitochondrial metabolic pathways, cytoskeletal proteins and proteins involved in protein folding are more conserved between Mesostigma and Chlamydomonas than between Mesostigma and the embryophytes. Conclusion Our EST-analysis of Mesostigma supports the notion that this organism should be a suitable unicellular model for the last flagellate common ancestor of the streptophytes. Mesostigma shares more genes with the embryophytes than with the chlorophyte Chlamydomonas reinhardtii, although both organisms are flagellate unicells. Thus, it seems likely that several major physiological changes (e.g. in the regulation of photosynthesis and photorespiration

  8. Chemotactic activity of cotyledons for mononuclear leukocytes related to occurrence of retained placenta in dexamethasone induced parturition in cattle.

    PubMed

    Benedictus, L; Jorritsma, R; Knijn, H M; Vos, P L A M; Koets, A P

    2011-09-15

    Induction of parturition with glucocorticosteroids in cattle is used for research purposes, in diseased or injured pregnant cows, and as a management tool to time parturition. A negative side effect of induction of parturition with glucocorticosteroids is the high incidence of retained placenta that occurs after these calvings. Reaction of the maternal immune system against the 'foreign' foetal membranes contributes to the breakdown of the foetal-maternal attachment. Several studies indicate that failure of this immune assisted detachment increases the occurrence of retained placenta. We hypothesized that retained placenta occurring after induction of parturition with glucocorticosteroids is caused by failure of immune assisted detachment of the foetal membranes. The chemotactic activity of cotyledons for mononuclear leukocytes was used as a parameter to see whether immune assisted detachment of the foetal membranes had occurred. Cotyledons were collected from spontaneously calving non-retained placenta cows and from dexamethasone induced non-retained placenta and retained placenta cows. The study showed that the chemotactic activity of cotyledons for mononuclear leukocytes was lower (P < 0.001) in cotyledons obtained from retained placenta cows in which parturition was induced with dexamethasone compared to the chemotactic activity of cotyledons obtained from spontaneously calving non-retained placenta cows, whereas the chemotactic activity of cotyledons obtained from induced non-retained placenta cows was not lower (P = 0.10) than the chemotactic activity of cotyledons obtained from spontaneously calving non-retained placenta cows. We concluded that induction of parturition with dexamethasone causes a failure of immune assisted detachment of the foetal membranes and the accompanying release of chemotactic factors. As a result, the chemotactic activity of cotyledons for mononuclear leukocytes is lower in induced retained placenta cows than in cotyledons from non

  9. Clinical and pathological observations on natural infections of cryptosporidiosis and flagellate protozoa in leopard geckos (Eublepharis macularius).

    PubMed

    Taylor, M A; Geach, M R; Cooley, W A

    1999-12-11

    A group of adult leopard geckos (Eublepharis macularius) which had been losing weight for several months were found to be infected with Cryptosporidium species. Histological and electron microscopical investigations on the intestines of five of the lizards revealed the presence of large numbers of the developmental stages of Cryptosporidium species attached to the mucosal surface of the lower intestine, and large numbers of flagellate protozoa, suspected to be predominantly Trichomonas species, in the gut lumen. The clinical signs were attributed to the presence of one or both types of parasites.

  10. 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

  11. 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

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

    PubMed Central

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

    2016-01-01

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

  13. Trypanosoma cruzi alkaline 2-DE: Optimization and application to comparative proteome analysis of flagellate life stages

    PubMed Central

    Magalhães, Adriana D; Charneau, Sébastien; Paba, Jaime; Guércio, Rafael AP; Teixeira, Antonio RL; Santana, Jaime M; Sousa, Marcelo V; Ricart, Carlos AO

    2008-01-01

    Background Trypanosoma cruzi, a flagellate protozoan, is the etiological agent of Chagas disease, a chronic illness that causes irreversible damage to heart and digestive tract in humans. Previous 2-DE analyses of T. cruzi proteome have not focused on basic proteins, possibly because of inherent difficulties for optimizing 2-DE in the alkaline pH range. However, T. cruzi wide pH range 2-DE gels have shown few visible spots in the alkaline region, indicating that the parasite either did not have an appreciable amount of alkaline proteins or that these proteins were underrepresented in the 2-DE gels. Results Different IEF conditions using 6–11 pH gradient strips were tested for separation of T. cruzi alkaline proteins. The optimized methodology described here was performed using anodic "paper bridge" sample loading supplemented by increased concentration of DTT and Triton X-100 on Multiphor II (GE Healthcare) equipment and an electrode pad embedded in DTT- containing solution near the cathode in order to avoid depletion of reducing agent during IEF. Landmark proteins were identified by peptide mass fingerprinting allowing the production of an epimastigote 2-DE map. Most identified proteins corresponded to metabolic enzymes, especially those related to amino acid metabolism. The optimized 2-DE protocol was applied in combination with the "two-in-one gel" method to verify the relative expression of the identified proteins between samples from epimastigote and trypomastigote life stages. Conclusion High resolution 2-DE gels of T. cruzi life forms were achieved using the optimized methodology and a partial epimastigote alkaline 2-DE map was built. Among 700 protein spots detected, 422 were alkaline with a pI above 7.0. The "two-in-one gel" method simplified the comparative analysis between T. cruzi life stages since it minimized variations in spot migration and silver-stained spot volumes. The comparative data were in agreement with biological traits of T. cruzi life

  14. Effect of intravascular neutrophil chemotactic factors on blood neutrophil and platelet kinetics

    SciTech Connect

    Issekutz, A.C.; Ripley, M.

    1986-02-01

    Intravenous infusion of an analogue (f-met-leu-phe (FMLP)) of a bacterial-derived polymorphonuclear leukocyte (PMNL) chemotactic factor, or of the complement-derived chemotactic stimulus, zymosan-activated plasma (ZAP, containing C5ades Arg) into rabbits induces acute PMNL margination in the pulmonary vasculature. The pulmonary PMNL sequestration is accompanied by thrombocytopenia. Because of the role platelets and PMNLs play in hemostasis and defense against infection, we studied the fate of these blood elements following sequestration induced by chemotactic factors. By employing 111In-labelled platelets and external radioisotope scanning, platelets were found to sequester in the pulmonary vasculature during FMLP infusion. Simultaneous 51Cr PMNL and 111In-platelet studies showed that following sequestration, PMNLs returned to the circulation and disappeared with a normal half-life (T1/2) whereas the T1/2 of the platelets was markedly shortened (T1/2 of control = 49 +/- 3.0 hr; FMLP or ZAP infused T1/2 = 27 +/- 2.7 hr). Infusion of platelet-activating factor (PAF) induced PMN and platelet sequestration with similar abnormalities in platelet kinetics. Studies with 51Cr- and 14C-serotonin-labelled platelets showed that platelets did not release serotonin during FMLP, ZAP, or low dose PAF-induced sequestration. In contrast to platelet survival, platelet size, platelet aggregation responses, and platelet glycoproteins were not affected by transient sequestration. These results indicate that during PMNL margination induced by relatively pure PMNL stimuli such as FMLP, platelets may reversibly marginate and subsequently be cleared at an accelerated rate. The reason for accelerated platelet clearance is not a result of circulating platelet aggregates or detectable proteolytic modification of membrane glycoproteins.

  15. Identification of a chemoreceptor for tricarboxylic acid cycle intermediates: differential chemotactic response towards receptor ligands.

    PubMed

    Lacal, Jesús; Alfonso, Carlos; Liu, Xianxian; Parales, Rebecca E; Morel, Bertrand; Conejero-Lara, Francisco; Rivas, Germán; Duque, Estrella; Ramos, Juan L; Krell, Tino

    2010-07-23

    We report the identification of McpS as the specific chemoreceptor for 6 tricarboxylic acid (TCA) cycle intermediates and butyrate in Pseudomonas putida. The analysis of the bacterial mutant deficient in mcpS and complementation assays demonstrate that McpS is the only chemoreceptor of TCA cycle intermediates in the strain under study. TCA cycle intermediates are abundantly present in root exudates, and taxis toward these compounds is proposed to facilitate the access to carbon sources. McpS has an unusually large ligand-binding domain (LBD) that is un-annotated in InterPro and is predicted to contain 6 helices. The ligand profile of McpS was determined by isothermal titration calorimetry of purified recombinant LBD (McpS-LBD). McpS recognizes TCA cycle intermediates but does not bind very close structural homologues and derivatives like maleate, aspartate, or tricarballylate. This implies that functional similarity of ligands, such as being part of the same pathway, and not structural similarity is the primary element, which has driven the evolution of receptor specificity. The magnitude of chemotactic responses toward these 7 chemoattractants, as determined by qualitative and quantitative chemotaxis assays, differed largely. Ligands that cause a strong chemotactic response (malate, succinate, and fumarate) were found by differential scanning calorimetry to increase significantly the midpoint of protein unfolding (T(m)) and unfolding enthalpy (DeltaH) of McpS-LBD. Equilibrium sedimentation studies show that malate, the chemoattractant that causes the strongest chemotactic response, stabilizes the dimeric state of McpS-LBD. In this respect clear parallels exist to the Tar receptor and other eukaryotic receptors, which are discussed.

  16. On the role of 25-hydroxycholesterol synthesis by glioblastoma cell lines. Implications for chemotactic monocyte recruitment.

    PubMed

    Eibinger, Gerald; Fauler, Günter; Bernhart, Eva; Frank, Sasa; Hammer, Astrid; Wintersperger, Andrea; Eder, Hans; Heinemann, Akos; Mischel, Paul S; Malle, Ernst; Sattler, Wolfgang

    2013-07-15

    Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor and is invariably fatal to affected patients. Oxysterols belong to a class of bioactive lipids that are implicated in neurological disease and are associated with various types of cancer. Here, we investigated expression and transcriptional regulation of cholesterol 25-hydroxylase (CH25H) in human U87MG and GM133 glioblastoma cell lines. We demonstrate that in both cell lines transcription and translation of CH25H are increased in response to TNFα and IL1β. In parallel, both cell lines upregulate 25-hydroxycholesterol (25-OHC) synthesis and secretion to levels comparable to bone marrow-derived mouse macrophages under inflammatory conditions. To determine whether 25-OHC acts as chemoattractant for tumor-associated macrophages, the human THP-1 monoblastic leukemia cell line was treated with varying amounts of the oxysterol. Experiments revealed that 25-OHC and lipid extracts isolated from GM133-conditioned medium (containing 7-fold higher 25-OHC concentrations than U87MG medium) induce chemotactic migration of THP-1 cells. Of note, 25-OHC also induced the migration of primary human peripheral blood monocytes. In response to exogenously added 25-OHC, THP-1 cells reorganized intermediate filament-associated vimentin to more cortical and polarized structures. Chemotactic migration of monocytes in response to 25-OHC was pertussis toxin-sensitive, indicating the involvement of G protein-coupled receptors. Using RNA interference we demonstrated that G protein-coupled receptor 183 (EBI2) contributes to 25-OHC-mediated chemotactic migration of THP-1 cells. These in vitro data indicate that GBM-derived and secreted 25-OHC may be involved in the recruitment of immune-competent cells to a tumor via EBI2.

  17. 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

  18. In vitro analysis of chemotactic leukocyte migration in 3D environments.

    PubMed

    Sixt, Michael; Lämmermann, Tim

    2011-01-01

    Cell migration on two-dimensional (2D) substrates follows entirely different rules than cell migration in three-dimensional (3D) environments. This is especially relevant for leukocytes that are able to migrate in the absence of adhesion receptors within the confined geometry of artificial 3D extracellular matrix scaffolds and within the interstitial space in vivo. Here, we describe in detail a simple and economical protocol to visualize dendritic cell migration in 3D collagen scaffolds along chemotactic gradients. This method can be adapted to other cell types and may serve as a physiologically relevant paradigm for the directed locomotion of most amoeboid cells.

  19. 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

  20. 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.

  1. The dependence of the swimming efficiency of multi-flagellated bacteria on the geometric arrangement of flagella

    NASA Astrophysics Data System (ADS)

    Watari, Nobuhiko; Larson, Ronald

    2010-11-01

    Multi-flagellated bacteria, such as Escherichia coli, often have flagella attached at random locations to the cell body. To study the effect of the number of flagella and the geometric arrangement of them to the swimming efficiency, we develop a simulation method using a bead-spring model to account for the hydrodynamic and the mechanical interactions between multiple flagella and the cell body. First, a modeled bacterium is constructed using beads, which represent the hydrodynamic drag centers of the geometric elements of the bacterium. This modeled bacterium swims by rotating the flagella with constant torques at the bases of them. We have found that for modeled bacteria with two flagella, the swimming speed varies by 30% depending on the position of the base of the flagellum along the cell body, which affects the tightness of the bundling. We have also found that overly rigid flagella can slow migration by inhibiting flagellar bundling, since bundling requires some adjustment in flagellar shape to compensate for helical phase miss-match produced by irregular flagellar positioning. In general, by changing the geometric arrangement and the number of flagella, our simulation enables us to determine the optimal designing of a flagellated micro-swimmer.

  2. 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.

  3. 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.

  4. 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

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

    PubMed Central

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

    2015-01-01

    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

  6. Association of calprotectin with leukocyte chemotactic and inflammatory mediators following acute aerobic exercise.

    PubMed

    Maharaj, Arun; Slusher, Aaron L; Zourdos, Michael C; Whitehurst, Michael; Fico, Brandon G; Huang, Chun-Jung

    2016-01-01

    The objective of this study was to examine whether acute aerobic exercise-mediated calprotectin in plasma would be associated with monocyte chemotactic protein-1 (MCP-1), myeloperoxidase (MPO), and interleukin-6 (IL-6) in healthy individuals. Eleven healthy participants, aged 18 to 30 years, were recruited to perform a 30-min bout of aerobic exercise at 75% maximal oxygen uptake. Acute aerobic exercise elicited a significant elevation across time in plasma calprotectin, MCP-1, MPO, and IL-6. Body mass index (BMI) was positively correlated with calprotectin area-under-the-curve with "respect to increase" (AUCi) and IL-6 AUCi. Furthermore, calprotectin AUCi was positively correlated with IL-6 AUCi and MPO AUCi, even after controlling for BMI. Although MPO AUCi was positively correlated with IL-6 AUCi, this relationship no longer existed after controlling for BMI. These results suggest that acute aerobic exercise could mediate innate immune response associated with calprotectin and its related leukocyte chemotactic and inflammatory mediators, especially in individuals with elevated BMI.

  7. Multi-phasic bi-directional chemotactic responses of the growth cone

    PubMed Central

    Naoki, Honda; Nishiyama, Makoto; Togashi, Kazunobu; Igarashi, Yasunobu; Hong, Kyonsoo; Ishii, Shin

    2016-01-01

    The nerve growth cone is bi-directionally attracted and repelled by the same cue molecules depending on the situations, while other non-neural chemotactic cells usually show uni-directional attraction or repulsion toward their specific cue molecules. However, how the growth cone differs from other non-neural cells remains unclear. Toward this question, we developed a theory for describing chemotactic response based on a mathematical model of intracellular signaling of activator and inhibitor. Our theory was first able to clarify the conditions of attraction and repulsion, which are determined by balance between activator and inhibitor, and the conditions of uni- and bi-directional responses, which are determined by dose-response profiles of activator and inhibitor to the guidance cue. With biologically realistic sigmoidal dose-responses, our model predicted tri-phasic turning response depending on intracellular Ca2+ level, which was then experimentally confirmed by growth cone turning assays and Ca2+ imaging. Furthermore, we took a reverse-engineering analysis to identify balanced regulation between CaMKII (activator) and PP1 (inhibitor) and then the model performance was validated by reproducing turning assays with inhibitions of CaMKII and PP1. Thus, our study implies that the balance between activator and inhibitor underlies the multi-phasic bi-directional turning response of the growth cone. PMID:27808115

  8. Collective Chemotactic Cell Movement; a Key Mechanism of Development and Morphogenesis

    NASA Astrophysics Data System (ADS)

    Weijer, Cornelis

    2011-03-01

    We investigate the molecular mechanisms by which cells produce and detect chemotactic signals and translate this information in directed movement up or down chemical gradients in the social amoebae Dictyostelium discoideum, and during gastrulation in the chick embryo. Investigation of Dictyostelium mutants with changes in cAMP cell-cell signalling dynamics and chemotaxis, show how cellular heterogeneity in signalling dynamics and polarised activation of the actin-myosin cytoskeleton drive aggregation, cell sorting, slug formation and migration. Chemotactic cell movement also plays a critical role during gastrulation in the chick embryo a model for amniote development. We suggest that epiblast cell movement during the formation of the primitive streak as well as the movement of the mesoderm cells after their ingression through the streak is controlled by a combination of attractive and repulsive guidance cues. We use computer models explore signalling and cell movement interact to give rise to emergent phenomena at the tissue and organism level such as pattern formation and morphogenesis.

  9. 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.

  10. Leukocytes in chemotactic-fragment-induced lung inflammation. Vascular emigration and alveolar surface migration.

    PubMed Central

    Shaw, J. O.

    1980-01-01

    Lung inflammation was induced in rabbits by intratracheal injections of chemotactic fragments obtained from zymosan-activated serum (CF-ZAS), and the route of vascular emigration and alveolar surface interaction of polymorphonuclear leukocytes (PMNs) and monocytes migrating into the lung was characterized by transmission (TEM) and scanning (SEM) electron-microscopic examination. Leukocytes migrated from capillaries and venules into the alveolar wall interstitium by adherence to the vascular endothelium and migration through the endothelial intracellular junction to attain a position between a reapposed endothelial cell junction and the vascular basement membrane. The cells then migrated into the interstitium through a narrow opening in the basement membrane. Leukocyte entrance into the alveolar space from the interstitium appeared to occur through small openings in the epithelial basement membrane at or near the Type I epithelial intercellular junction. Once in the alveolus, PMNs and macrophages demonstrated surface adherence and spreading along with evidence of migration, pseudopod extension, interalveolar pore transit, and retraction fiber formation. This study indicates the leukocyte influx into the alveolus in acute chemotactic-factor-induced inflammation is via a continuum of migrational activity, beginning at the pulmonary capillary endothelial surface and persisting on the alveolar epithelial surface. Images Figure 10 Figure 11 Figure 12 Figure 1 Figure 2 Figure 3 Figure 13 Figure 14 Figure 4 Figure 5 Figure 6 Figure 15 Figure 7 Figure 8 Figure 16 Figure 9 PMID:7435538

  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.

  12. Multi-phasic bi-directional chemotactic responses of the growth cone

    NASA Astrophysics Data System (ADS)

    Naoki, Honda; Nishiyama, Makoto; Togashi, Kazunobu; Igarashi, Yasunobu; Hong, Kyonsoo; Ishii, Shin

    2016-11-01

    The nerve growth cone is bi-directionally attracted and repelled by the same cue molecules depending on the situations, while other non-neural chemotactic cells usually show uni-directional attraction or repulsion toward their specific cue molecules. However, how the growth cone differs from other non-neural cells remains unclear. Toward this question, we developed a theory for describing chemotactic response based on a mathematical model of intracellular signaling of activator and inhibitor. Our theory was first able to clarify the conditions of attraction and repulsion, which are determined by balance between activator and inhibitor, and the conditions of uni- and bi-directional responses, which are determined by dose-response profiles of activator and inhibitor to the guidance cue. With biologically realistic sigmoidal dose-responses, our model predicted tri-phasic turning response depending on intracellular Ca2+ level, which was then experimentally confirmed by growth cone turning assays and Ca2+ imaging. Furthermore, we took a reverse-engineering analysis to identify balanced regulation between CaMKII (activator) and PP1 (inhibitor) and then the model performance was validated by reproducing turning assays with inhibitions of CaMKII and PP1. Thus, our study implies that the balance between activator and inhibitor underlies the multi-phasic bi-directional turning response of the growth cone.

  13. Computational modeling of chemotactic signaling and aggregation of microglia around implantation site during deep brain stimulation

    NASA Astrophysics Data System (ADS)

    Silchenko, A. N.; Tass, P. A.

    2013-10-01

    It is well established that prolonged electrical stimulation of brain tissue causes massive release of ATP in the extracellular space. The released ATP and the products of its hydrolysis, such as ADP and adenosine, become the main elements mediating chemotactic sensitivity and motility of microglial cells via subsequent activation of P2Y2,12 as well as A3A and A2A adenosine receptors. The size of the sheath around the electrode formed by the microglial cells is an important criterion for the optimization of the parameters of electrical current delivered to brain tissue. Here, we study a purinergic signaling pathway underlying the chemotactic motion of microglia towards the implanted electrode during deep brain stimulation. We present a computational model describing formation of a stable aggregate around the implantation site due to the joint chemo-attractive action of ATP and ADP together with a mixed influence of extracellular adenosine. The model was built in accordance with the classical Keller-Segel approach and includes an equation for the cells' density as well as equations describing the hydrolysis of extracellular ATP via successive reaction steps ATP →ADP →AMP →adenosine. The results of our modeling allowed us to reveal the dependence of the width of the encapsulating layer around the electrode on the amount of ATP released due to permanent electrical stimulation. The dependences of the aggregates' size on the parameter governing the nonlinearity of interaction between extracellular adenosine and adenosine receptors are also analyzed.

  14. 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.

  15. Spatial regulation of the cAMP-dependent protein kinase during chemotactic cell migration

    PubMed Central

    Howe, Alan K.; Baldor, Linda C.; Hogan, Brian P.

    2005-01-01

    Historically, the cAMP-dependent protein kinase (PKA) has a paradoxical role in cell motility, having been shown to both facilitate and inhibit actin cytoskeletal dynamics and cell migration. In an effort to understand this dichotomy, we show here that PKA is regulated in subcellular space during cell migration. Immunofluorescence microscopy and biochemical enrichment of pseudopodia showed that type II regulatory subunits of PKA and PKA activity are enriched in protrusive cellular structures formed during chemotaxis. This enrichment correlates with increased phosphorylation of key cytoskeletal substrates for PKA, including the vasodilator-stimulated phosphoprotein (VASP) and the protein tyrosine phosphatase containing a PEST motif. Importantly, inhibition of PKA activity or its ability to interact with A kinase anchoring proteins inhibited the activity of the Rac GTPase within pseudopodia. This effect correlated with both decreased guanine nucleotide exchange factor activity and increased GTPase activating protein activity. Finally, inhibition of PKA anchoring, like inhibition of total PKA activity, inhibited pseudopod formation and chemotactic cell migration. These data demonstrate that spatial regulation of PKA via anchoring is an important facet of normal chemotactic cell movement. PMID:16176981

  16. Spatial regulation of the cAMP-dependent protein kinase during chemotactic cell migration.

    PubMed

    Howe, Alan K; Baldor, Linda C; Hogan, Brian P

    2005-10-04

    Historically, the cAMP-dependent protein kinase (PKA) has a paradoxical role in cell motility, having been shown to both facilitate and inhibit actin cytoskeletal dynamics and cell migration. In an effort to understand this dichotomy, we show here that PKA is regulated in subcellular space during cell migration. Immunofluorescence microscopy and biochemical enrichment of pseudopodia showed that type II regulatory subunits of PKA and PKA activity are enriched in protrusive cellular structures formed during chemotaxis. This enrichment correlates with increased phosphorylation of key cytoskeletal substrates for PKA, including the vasodilator-stimulated phosphoprotein (VASP) and the protein tyrosine phosphatase containing a PEST motif. Importantly, inhibition of PKA activity or its ability to interact with A kinase anchoring proteins inhibited the activity of the Rac GTPase within pseudopodia. This effect correlated with both decreased guanine nucleotide exchange factor activity and increased GTPase activating protein activity. Finally, inhibition of PKA anchoring, like inhibition of total PKA activity, inhibited pseudopod formation and chemotactic cell migration. These data demonstrate that spatial regulation of PKA via anchoring is an important facet of normal chemotactic cell movement.

  17. 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.

  18. 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.

  19. Macrophage inflammatory protein-1 alpha. A novel chemotactic cytokine for macrophages in rheumatoid arthritis.

    PubMed Central

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

    1994-01-01

    We have shown that human macrophages (m phi s) play an important role in the elaboration of chemotactic cytokines in rheumatoid arthritis (RA) (Koch, A. E., S. L. Kunkel, J. C. Burrows, H. L. Evanoff, G. K. Haines, R. M. Pope, and R. M. Strieter. 1991. J. Immunol. 147:2187; Koch, A. E., S. L. Kunkel, L. A. Harlow, B. Johnson, H. L. Evanoff, G. K. Haines, M. D. Burdick, R. M. Pope, and R. M. Strieter. 1992. J. Clin. Invest. 90:772; Koch, A. E., P. J. Polverini, S. L. Kunkel, L. A. Harlow, L. A. DiPietro, V. M. Elner, S. G. Elner, and R. M. Strieter. 1992. Science (Wash. DC). 258:1798). Recently, m phi inflammatory protein-1 (MIP-1 alpha), a cytokine with chemotactic activity for m phi s and neutrophils (PMNs), has been described. We have examined the production of MIP-1 alpha using sera, synovial fluid (SF), and synovial tissue (ST) from 63 arthritic patients. MIP-1 alpha was higher in RA SF (mean, 29 +/- 8 ng/ml [SE]) compared with other forms of arthritis (2.8 +/- 1.7), or osteoarthritis (0.7 +/- 0.4; P < 0.05). RA SF MIP-1 alpha was greater than that found in either RA or normal peripheral blood (PB) (P < 0.05). Anti-MIP-1 alpha neutralized 36 +/- 3% (mean +/- SE) of the chemotactic activity for m phi s, but not PMNs, found in RA SFs. RA SF and PB mononuclear cells produced antigenic MIP-1 alpha. Mononuclear cell MIP-1 alpha production was augmented with phytohemagglutinin or LPS. Isolated RA ST fibroblast production of antigenic MIP-1 alpha was augmented upon incubation of cells with LPS, and to a lesser extent with tumor necrosis factor-alpha. Isolated RA ST m phi s expressed constitutive MIP-1 alpha mRNA and antigenic MIP-1 alpha. Using ST immunohistochemistry, MIP-1 alpha+ cells from RA compared with normal were predominantly m phi s and lining cells (P < 0.05). These results suggest that MIP-1 alpha plays a role in the selective recruitment of m phi s in synovial inflammation associated with RA. Images PMID:8132778

  20. Expression of adhesion molecules and chemotactic cytokines in cultured human mesothelial cells.

    PubMed

    Jonjić, N; Peri, G; Bernasconi, S; Sciacca, F L; Colotta, F; Pelicci, P; Lanfrancone, L; Mantovani, A

    1992-10-01

    The mesothelium is a flat epithelial lining of serous cavities that could gate the traffic of molecules and cells between the circulation and these body compartments. The present study was designed to elucidate the capacity of mesothelial cells to express adhesion molecules and chemoattractant cytokines, two fundamental mechanisms of regulation of leukocyte recruitment. Cultured human mesothelial cells express appreciable levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and these were increased by in vitro exposure to tumor necrosis factor (TNF), interferon gamma (IFN-gamma), or TNF and IFN-gamma. Interleukin 1 (IL-1) was a less consistent stimulus for adhesion molecule expression in vitro. Unlike endothelial cells, used as a reference cell population, resting or stimulated mesothelial cells did not express E-selectin and ICAM-2, as assessed by flow cytometry. Analysis of VCAM-1 mRNA by reverse transcriptase and polymerase chain reaction using appropriate primers revealed that mesothelial cells expressed both the seven- and the six-Ig domain transcripts, with predominance of the longer species. Monocytes bound appreciably to "resting" and, to a greater extent, to stimulated mesothelial cells. Monocytes exposed to IFN-gamma and lipopolysaccharide, used as prototypic activation signals, showed increased capacity to bind mesothelial cells. Anti-CD18 monoclonal antibody significantly inhibited binding of monocytes to mesothelial cells, and this blocking effect was amplified by anti-very late antigen 4. Mesothelial cells were able to express the chemotactic cytokines IL-8 and monocyte chemotactic protein 1 at the mRNA and protein levels. These results indicate that mesothelial cells can express a set of adhesion molecules (ICAM-1 and VCAM-1) overlapping with, but distinct from, that expressed in vascular endothelium (ICAM-1, ICAM-2, VCAM-1, E-selectin), and that these are functionally relevant for interacting with

  1. 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

  2. Promotion of formyl peptide receptor 1-mediated neutrophil chemotactic migration by antimicrobial peptides isolated from the centipede Scolopendra subspinipes mutilans

    PubMed Central

    Park, Yoo Jung; Lee, Sung Kyun; Jung, Young Su; Lee, Mingyu; Lee, Ha Young; Lee, Ha Young; Park, Joon Seong; Koo, JaeHyung; Koo, JaeHyung; Bae, Yoe-Sik

    2016-01-01

    We investigated the effects of two antimicrobial peptides (AMPs) isolated from Scolopendra subspinipes mutilans on neutrophil activity. Stimulation of mouse neutrophils with the two AMPs elicited chemotactic migration of the cells in a pertussis toxin-sensitive manner. The two AMPs also stimulated activation of ERK and Akt, which contribute to chemotactic migration of neutrophils. We found that AMP-stimulated neutrophil chemotaxis was blocked by a formyl peptide receptor (FPR) 1 antagonist (cyclosporin H); moreover the two AMPs stimulated the chemotactic migration of FPR1-expressing RBL-2H3 cells but not of vector-expressing RBL-2H3 cells. We also found that the two AMPs stimulate neutrophil migration in vivo, and that this effect is blocked in FPR1-deficient mice. Taken together, our results suggest that the two AMPs stimulate neutrophils, leading to chemotactic migration through FPR1, and the two AMPs will be useful for the study of FPR1 signaling and neutrophil activation. [BMB Reports 2016; 49(9): 520-525] PMID:27502013

  3. A 'chemotactic dipole' mechanism for large-scale vortex motion during primitive streak formation in the chick embryo.

    PubMed

    Sandersius, S A; Chuai, M; Weijer, C J; Newman, T J

    2011-08-01

    Primitive streak formation in the chick embryo involves significant coordinated cell movement lateral to the streak, in addition to the posterior-anterior movement of cells in the streak proper. Cells lateral to the streak are observed to undergo 'polonaise movements', i.e. two large counter-rotating vortices, reminiscent of eddies in a fluid. In this paper, we propose a mechanism for these movement patterns which relies on chemotactic signals emitted by a dipolar configuration of cells in the posterior region of the epiblast. The 'chemotactic dipole' consists of adjacent regions of cells emitting chemo-attractants and chemo-repellents. We motivate this idea using a mathematical analogy between chemotaxis and electrostatics, and test this idea using large-scale computer simulations. We implement active cell response to both neighboring mechanical interactions and chemotactic gradients using the Subcellular Element Model. Simulations show the emergence of large-scale vortices of cell movement. The length and time scales of vortex formation are in reasonable agreement with experimental data. We also provide quantitative estimates for the robustness of the chemotaxis dipole mechanism, which indicate that the mechanism has an error tolerance of about 10% to variation in chemotactic parameters, assuming that only 1% of the cell population is involved in emitting signals. This tolerance increases for larger populations of cells emitting signals.

  4. Promotion of formyl peptide receptor 1-mediated neutrophil chemotactic migration by antimicrobial peptides isolated from the centipede Scolopendra subspinipes mutilans.

    PubMed

    Park, Yoo Jung; Lee, Sung Kyun; Jung, Young Su; Lee, Mingyu; Lee, Ha Young; Kim, Sang Doo; Park, Joon Seong; Koo, JaeHyung; Hwang, Jae Sam; Bae, Yoe-Sik

    2016-09-01

    We investigated the effects of two antimicrobial peptides (AMPs) isolated from Scolopendra subspinipes mutilans on neutrophil activity. Stimulation of mouse neutrophils with the two AMPs elicited chemotactic migration of the cells in a pertussis toxin-sensitive manner. The two AMPs also stimulated activation of ERK and Akt, which contribute to chemotactic migration of neutrophils. We found that AMP-stimulated neutrophil chemotaxis was blocked by a formyl peptide receptor (FPR) 1 antagonist (cyclosporin H); moreover the two AMPs stimulated the chemotactic migration of FPR1-expressing RBL-2H3 cells but not of vector-expressing RBL-2H3 cells. We also found that the two AMPs stimulate neutrophil migration in vivo, and that this effect is blocked in FPR1-deficient mice. Taken together, our results suggest that the two AMPs stimulate neutrophils, leading to chemotactic migration through FPR1, and the two AMPs will be useful for the study of FPR1 signaling and neutrophil activation. [BMB Reports 2016; 49(9): 520-525].

  5. 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...

  6. 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

  7. A continuum analysis of the chemotactic signal seen by Dictyostelium discoideum.

    PubMed

    Dallon, J C; Othmer, H G

    1998-10-21

    We developed a mathematical model of cell-to-cell-signalling in Dictyostelium discoideum that predicts the cAMP signal seen by individual cells in early aggregation. The model employs two cells on a plane and is designed to predict the space-time characteristics of both the extracellular cAMP signal seen by one cell when a nearby cell relays, and the intracellular cAMP response produced by the stimulus in the receiving cell. The effect of membrane bound phosphodiesterase is studied and it is shown that cells can orient effectively even in its absence. Our results give a detailed picture of how the spatio-temporal characteristics of the extracellular signal can be transduced into a time- and space-dependent intracellular gradient, and they suggest a plausible mechanism for orientation in a natural chemotactic wave.

  8. PTEN functions to 'prioritize' chemotactic cues and prevent 'distraction' in migrating neutrophils.

    PubMed

    Heit, Bryan; Robbins, Stephen M; Downey, Charlene M; Guan, Zhiwen; Colarusso, Pina; Miller, B Joan; Jirik, Frank R; Kubes, Paul

    2008-07-01

    Neutrophils encounter and 'prioritize' many chemoattractants in their pursuit of bacteria. Here we tested the possibility that the phosphatase PTEN is responsible for the prioritization of chemoattractants. Neutrophils induced chemotaxis by two separate pathways, the phosphatidylinositol-3-OH kinase (PI(3)K) phosphatase and tensin homolog (PTEN) pathway, and the p38 mitogen-activated protein kinase pathway, with the p38 pathway dominating over the PI(3)K pathway. Pten(-/-) neutrophils could not prioritize chemoattractants and were 'distracted' by chemokines when moving toward bacterial chemoattractants. In opposing gradients, PTEN became distributed throughout the cell circumference, which inhibited all PI(3)K activity, thus permitting 'preferential' migration toward bacterial products via phospholipase A(2) and p38. Such prioritization was defective in Pten(-/-) neutrophils, which resulted in defective bacterial clearance in vivo. Our data identify a PTEN-dependent mechanism in neutrophils to prioritize, 'triage' and integrate responses to multiple chemotactic cues.

  9. Biodegradation of naphthalene and anthracene by chemo-tactically active rhizobacteria of populus deltoides

    PubMed Central

    Bisht, Sandeep; Pandey, Piyush; Sood, Anchal; Sharma, Shivesh; Bisht, N. S.

    2010-01-01

    Several naphthalene and anthracene degrading bacteria were isolated from rhizosphere of Populus deltoides, which were growing in non-contaminated soil. Among these, four isolates, i.e. Kurthia sp., Micrococcus varians, Deinococcus radiodurans and Bacillus circulans utilized chrysene, benzene, toluene and xylene, in addition to anthracene and naphthalene. Kurthia sp and B. circulans showed positive chemotactic response for naphthalene and anthracene. The mean growth rate constant (K) of isolates were found to increase with successive increase in substrate concentration (0.5 to 1.0 mg/50ml). B. circulans SBA12 and Kurthia SBA4 degraded 87.5% and 86.6% of anthracene while, Kurthia sp. SBA4, B. circulans SBA12, and M. varians SBA8 degraded 85.3 %, 95.8 % and 86.8 % of naphthalene respectively after 6 days of incubation as determined by HPLC analysis. PMID:24031572

  10. 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

  11. Total chemical synthesis and chemotactic activity of human S100A12 (EN-RAGE).

    PubMed

    Miranda, L P; Tao, T; Jones, A; Chernushevich, I; Standing, K G; Geczy, C L; Alewood, P F

    2001-01-12

    Human S100A12 (extracellular newly identified RAGE (receptor for advanced glycosylation end products)-binding protein), a new member of the S100 family of EF-hand calcium-binding proteins, was chemically synthesised using highly optimised 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate/tert-butoxycarbonyl in situ neutralisation solid-phase chemistry. Circular dichroism studies indicated that CaCl(2) decreased the helical content by 27% whereas helicity was marginally increased by ZnCl(2). The propensity of S100A12 to dimerise was examined by electrospray ionisation time-of-flight mass spectrometry which clearly demonstrated the prevalence of the non-covalent homodimer (20890 Da). Importantly, synthetic human S100A12 in the nanomolar range was chemotactic for neutrophils and macrophages in vitro.

  12. Modulating Influence of Chemotactic Factor-Induced Cell Adhesiveness on Granulocyte Function

    PubMed Central

    Fehr, Jorg; Dahinden, Clemens

    1979-01-01

    The importance of adhesion in regulating locomotion and accumulation of polymorphonuclear leukocytes (PMN) has remained vague. We found that the chemotaxis of human PMN resuspended in heat-inactivated plasma was maximal toward 1-10 nM N-formyl-met-leu-phe (f-Met-Leu-Phe), but fell below random motility toward ≥ 100 nM. This impressive decrease of motility was paralleled by increased cell adherence on Petri dishes being minimal at 1 nM and maximal at >10 nM f-Met-Leu-Phe (6±1 and 37±2% [SE] adherent cells, respectively). Checked by phase-contrast microscopy, cells under stimulated adhesion lost the typical bipolar shape of moving PMN and became immobilized and highly flattened. PMN, preexposed to 250 nM f-Met-Leu-Phe and tested after washing, retained increased adhesiveness and showed extremely low random and chemotactic motility. In contrast, preexposure to 1 nM f-Met-Leu-Phe had no effect on chemotaxis. Supporting the concept that immobilizing hyperadhesiveness does not correspond to a general functional hyporesponsiveness of PMN, no depression of the initial ingestion rate was observed in the presence of 250 nM f-Met-Leu-Phe. Moreover, a close correlation was found between the induction of PMN adhesiveness and the stimulation of the hexose monophosphate pathway activity as well as of lysomal enzyme release (r ≥ 0.98). Thus, “chemotactic deactivation” and “high-dose inhibition of chemotaxis” by N-formyl peptides is the consequence of increased cell adhesiveness. This phenomenon provides a mechanism for cell trapping at the inflammatory site. Conversely, if operative in circulating blood, e.g., in septicemia, it may impair PMN emigration to such sites. Images PMID:447862

  13. Chemotactic chemokines are important in the pathogenesis of irritable bowel syndrome.

    PubMed

    Darkoh, Charles; Comer, Latoya; Zewdie, Getie; Harold, Stephen; Snyder, Ned; Dupont, Herbert L

    2014-01-01

    Irritable bowel syndrome (IBS) is one of the most frequently diagnosed disorders, affecting about 20% of the general population in Western countries. This syndrome poses an enormous socio-economic burden, impairs the quality of life substantially, and increases healthcare costs. IBS can be classified as either idiopathic (ID-IBS) with unknown etiology or post-infectious (PI-IBS), which develops after a bout of acute diarrhea or gastroenteritis. Little is known about the immunopathogenesis of these two forms of IBS. We evaluated various biomarkers in clinical samples of ID-IBS and PI-IBS patients with the goal to test the hypothesis that the immunologic presentations of these forms of IBS are similar, despite their apparent different etiologic origins. Sera and stool samples from PI-IBS, ID-IBS, and healthy volunteers were analyzed for relative amounts of 36 different biomarkers using the Proteome Profiler Human Cytokine Array Panel A Kit and quantitative ELISA. Our results demonstrated significantly high levels of chemotactic chemokines monocytes chemotactic protein-1 (CCL2) [p-value  = 0.003], macrophage inflammatory protein-1β (CCL4) [p-value  = 0.010], and CXCL16 (p-value 0.001) in the sera and stools of both ID-IBS and PI-IBS patients. Furthermore, pro-inflammatory cytokines (IFN-γ, IL-1β, and TNF-α) were significantly higher in IBS patients. Anti-inflammatory cytokines (IL-10, IL-4, and IL-13) were variable except IL-10, which was significantly higher in the healthy volunteers than the IBS patients. Remarkably, the amounts and expression pattern of these biomarkers were not significantly different between ID-IBS and PI-IBS. Thus, ID-IBS and PI-IBS present similar immunologic and clinical phenotypes, in spite of their different etiologic origins.

  14. Chemotactic effect of odorants and tastants on the ciliate Tetrahymena pyriformis.

    PubMed

    Láng, Júlia; Rákász, Virág; Magyar, Anna; Pállinger, Éva; Kohidai, László

    2011-12-01

    Naturally occurring aroma compounds are able to elicit physiological and migratory responses such as chemotaxis even at nano to femtomolar concentrations in organisms at different levels of phylogeny. Despite the amazing chemical variety of these substances the apparatus by which they can be detected i.e. the chemosensory receptors and the signaling pathways seem to be rather uniform and evolutionary well-conserved. The intracellular signaling process is supposed to be mediated by either cAMP or inositol 1,4,5-trisphosphate. The present work aimed to investigate the chemotactic behavior of 11 odorants that occur naturally in foods and are also used by the industry as additives, on the eukaryotic ciliate Tetrahymena pyriformis. Intracellular signaling pathways that might be activated by these compounds were also investigated. Activation of the phospholipase C (PLC) was measured by FACS and the stimulation of inositol-1,4,5-trisphosphate 3-kinases (IP3K) was measured using two specific inhibitors, wortmannin and LY294002. The strongest chemoattractant character was observed for isoamyl acetate (10(⁻6) M), propyl isobutyrate (10(⁻8) M), isobutyl propionate (10(⁻6) M). The strongest repellent action was exerted by benzyl acetate (10(⁻8) M), furfuryl thioacetate (10(⁻12) M). Our results suggest that Tetrahymena responds in a very sensitive way to slight changes in the molecular structure. According to our study, tracer amounts of solvents do not contribute significantly to the chemotactic profile of the respective odorants. No significant activation of PLC or PI3K could be observed following stimulation with attractant odorants which implies that some other pathways may be involved, hence further investigation is needed.

  15. Imaging focal sites of bacterial infection in rats with indium-111-labeled chemotactic peptide analogs

    SciTech Connect

    Fischman, A.J.; Pike, M.C.; Kroon, D.; Fucello, A.J.; Rexinger, D.; ten Kate, C.; Wilkinson, R.; Rubin, R.H.; Strauss, H.W. )

    1991-03-01

    Four DTPA-derivatized chemotactic peptide analogs: ForNleLFNleYK-DTPA (P1), ForMLFNH(CH2)6NH-DTPA (P2), ForNleLFK(NH2)-DTPA (P3), and ForNleLFK-DTPA (P4), were synthesized and evaluated for in vitro bioactivity and receptor binding. The peptides were radiolabeled with 111In by transchelation and their biodistribution determined in rats at 5, 30, 60 and 120 min after injection. Localization at sites of infection was determined by scintillation camera imaging in animals with deep-thigh infection due to Escherichia coli. Images were recorded from 5 min to 2 hr after injection. All peptides maintained biologic activity (EC50 for O2-production by human PMN's: 3-150 nM) and the ability to bind to the oligopeptide chemoattractant receptor on human PMN's (EC50 for binding: 7.5-50 nM); biologic activity and receptor binding were highly correlated (r = 0.99). For all the peptides, blood clearance was rapid (half-lives: 21.5, 33.1, 31.6, and 28.7 min for P1, P2, P3, and P4, respectively). Biodistributions of the individual peptides were similar with low levels of accumulation in the heart, lung, liver, spleen, and gastrointestinal tract. In the kidney, P1 had much greater accumulation than other organs. All peptides yielded high quality images of the infection sites within 1 hr of injection. This study demonstrates that 111In-labeled chemotactic peptide analogs were effective agents for the external imaging of focal sites of infection.

  16. Macrophage procoagulant-inducing factor. In vivo properties and chemotactic activity for phagocytic cells.

    PubMed

    Ryan, J; Geczy, C L

    1988-09-15

    Murine macrophage procoagulant-inducing factor (MPIF) is a lymphokine with chemical properties distinct from a number of well-characterized cytokines. MPIF induces procoagulant activity on the surface of macrophages and thus may play a central role in the expression of cell-mediated immunity. Highly enriched MPIF-alpha and -beta, separated by virtue of their basic isoelectric point and affinity for heparin, induced local induration and fibrin deposition and cellular infiltration similar to that observed in delayed type hypersensitivity reactions, when injected intradermally. Margination with of polymorphonuclear leukocytes (PMN) along the endothelium as well as increased PMN infiltration was evident after 4 h. In contrast to other inflammatory mediators (e.g., C5a, IL-1) reactivity was sustained, with greater numbers of mononuclear cells apparent 24 h after skin testing. Changes in the dermis were evident 4 h after MPIF injection with increased numbers of cells near areas where spaces in the collagen bundles had formed. Dermal thickening was evident after 24 h and collagen fiber structure was disrupted. Extravascular fibrinogen/fibrin was most prominent 24 h after testing. LPS, which induces macrophage procoagulant activity in vitro, did not induce the histopathologic changes evident with MPIF. MPIF was chemotactic for PMN and macrophages in vitro. Chemotactic activity was heat-labile and not due to C5a. Migration was dependent on a concentration gradient, as determined by checkerboard analysis, indicating that MPIF promoted chemotaxis rather than chemokinesis. Experiments reported here suggest that MPIF is an important mediator of fibrin deposition and cellular infiltration characteristic of cell-mediated immune response.

  17. Chemotactic response of frozen-thawed bovine spermatozoa towards follicular fluid.

    PubMed

    Gil, P I; Guidobaldi, H A; Teves, M E; Uñates, D R; Sanchez, R; Giojalas, L C

    2008-10-01

    The aim of this study was to verify whether cattle spermatozoa respond by chemotaxis to follicular fluid (FF). The experimental conditions were defined to maintain a frozen-thawed sperm population with great motility and capacitation, and lesser sperm agglutination. Several sperm preparation conditions were studied: sperm separation from the seminal plasma by Sephadex column or migration-sedimentation, incubation under capacitating conditions in the presence or absence of a superficial layer of mineral oil, and different pH of the culture medium. The percentage of motile and agglutinated spermatozoa was determined in plate dishes under inverted phase contrast microscope. The percentage of capacitated spermatozoa was calculated as the difference between the percentages of acrosome reacted spermatozoa with and without lysophosphatidylcholine stimulation. The most ideal experimental conditions to evaluate chemotaxis in frozen-thawed cattle spermatozoa were: to separate the cells from the seminal plasma by migration-sedimentation and to incubate them under oil, in culture medium at pH 7.2, for less than 2h. The chemotaxis assays were conducted with spermatozoa treated as mentioned above which were confronted to several dilutions of FF (1:10(3), 1:10(4), 1:10(5), 1:10(6)) in a chemotaxis chamber by videomicroscopy and computer image analysis. A subpopulation of capacitated spermatozoa ( approximately 10%) that responded chemotactically to a concentration gradient generated by FF (1:10(4) to 1:10(5)) was observed. Since cryopreserved spermatozoa are regularly used to artificially inseminate the cows, the sperm chemotactic response towards FF would be potentially used to diagnose the bull sperm sample or to select the spermatozoa in the most functional state.

  18. Malarial pigment hemozoin impairs chemotactic motility and transendothelial migration of monocytes via 4-hydroxynonenal.

    PubMed

    Skorokhod, Oleksii A; Barrera, Valentina; Heller, Regine; Carta, Franco; Turrini, Franco; Arese, Paolo; Schwarzer, Evelin

    2014-10-01

    Natural hemozoin, nHZ, is avidly phagocytosed in vivo and in vitro by human monocytes. The persistence of the undigested β-hematin core of nHZ in the phagocyte lysosome for long periods of time modifies several cellular immune functions. Here we show that nHZ phagocytosis by human primary monocytes severely impaired their chemotactic motility toward MCP-1, TNF, and FMLP, by approximately 80% each, and their diapedesis across a confluent human umbilical vein endothelial cell layer toward MCP-1 by 45±5%. No inhibition was observed with latex-fed or unfed monocytes. Microscopic inspection revealed polarization defects in nHZ-fed monocytes due to irregular actin polymerization. Phagocytosed nHZ catalyzes the peroxidation of polyunsaturated fatty acids and generation of the highly reactive derivative 4-hydroxynonenal (4-HNE). Similar to nHZ phagocytosis, the exposure of monocytes to in vivo-compatible 4-HNE concentrations inhibited cell motility in both the presence and the absence of chemotactic stimuli, suggesting severe impairment of cytoskeleton dynamics. Consequently, 4-HNE conjugates with the cytoskeleton proteins β-actin and coronin-1A were immunochemically identified in nHZ-fed monocytes and mass spectrometrically localized in domains of protein-protein interactions involved in cytoskeleton reorganization and cell motility. The molecular and functional modifications of actin and coronin by nHZ/4-HNE may also explain impaired phagocytosis, another motility-dependent process previously described in nHZ-fed monocytes. Further studies will show whether impaired monocyte motility may contribute to the immunodepression and the frequent occurrence of secondary infections observed in malaria patients.

  19. 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.

  20. Intestinal Dendritic Cells Are Altered in Number, Maturity and Chemotactic Ability in Fulminant Hepatic Failure

    PubMed Central

    Liu, Mei; Wang, Peng; Zhao, Min; Liu, DY

    2016-01-01

    Fulminant hepatic failure (FHF) is defined as rapid acute liver injury, often complicated with spontaneous bacterial peritonitis (SBP). The precise onset of FHF with SBP is still unknown, but it is thought that SBP closely correlates with a weakened intestinal barrier. Dendritic cells (DCs) play a crucial role in forming the intestinal immune barrier, therefore the number, maturity and chemotactic ability of intestinal DCs were studied in FHF. Mouse intestinal and spleen DCs were isolated by magnetic-activated cell sorting (MACS) and surface markers of DCs, namely CD11c, CD74, CD83 and CD86, were identified using flow cytometry. Immunohistochemistry and Western blotting were performed to detect the distribution and expression of CC-chemokine receptor 7 (CCR7) and CC-chemokine receptor 9 (CCR9), as well as their ligands-CC-chemokine ligand 21 (CCL21) and CC-chemokine ligand 25 (CCL25). Real-time PCR was used to detect CCR7 and CCR9 mRNA, along with their ligands-CCL21 and CCL25 mRNA. Flow cytometry analysis showed that the markers CD74, CD83 and CD86 of CD11c+DCs were lower in the D-galactosamine (D-GalN) group and were significantly decreased in the FHF group, while there were no significant changes in the expression of these markers in the lipopolysaccharide (LPS) group. Immunohistochemistry results showed that staining for CCR7 and CCR9, as well as their ligands CCL21 and CCL25, was significantly weaker in the D-GalN and FHF groups compared with the normal saline (NS) group or the LPS group; the FHF group even showed completely unstained parts. Protein expression of CCR7 and CCR9, as well as their ligands- CCL21 and CCL25, was also lower in the D-GalN group and decreased even more significantly in the FHF group. At the gene level, CCR7 and CCR9, along with CCL21 and CCL25 mRNA expression, was lower in the D-GalN group and significantly decreased in the FHF group compared to the NS and LPS groups, consisting with the protein expression. Our study indicated that

  1. 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.

  2. 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.

  3. RecA Protein Plays a Role in the Chemotactic Response and Chemoreceptor Clustering of Salmonella enterica

    PubMed Central

    Mayola, Albert; Irazoki, Oihane; Martínez, Ignacio A.; Petrov, Dmitri; Menolascina, Filippo; Stocker, Roman; Reyes-Darias, José A.; Krell, Tino; Barbé, Jordi; Campoy, Susana

    2014-01-01

    The RecA protein is the main bacterial recombinase and the activator of the SOS system. In Escherichia coli and Salmonella enterica sv. Typhimurium, RecA is also essential for swarming, a flagellar-driven surface translocation mechanism widespread among bacteria. In this work, the direct interaction between RecA and the CheW coupling protein was confirmed, and the motility and chemotactic phenotype of a S. Typhimurium ΔrecA mutant was characterized through microfluidics, optical trapping, and quantitative capillary assays. The results demonstrate the tight association of RecA with the chemotaxis pathway and also its involvement in polar chemoreceptor cluster formation. RecA is therefore necessary for standard flagellar rotation switching, implying its essential role not only in swarming motility but also in the normal chemotactic response of S. Typhimurium. PMID:25147953

  4. Abnormal neutrophil chemotactic activity in children with congenital insensitivity to pain with anhidrosis (CIPA): the role of nerve growth factor.

    PubMed

    Beigelman, Avraham; Levy, Jacov; Hadad, Nurit; Pinsk, Vered; Haim, Alon; Fruchtman, Yariv; Levy, Rachel

    2009-03-01

    A 1926-ins-T mutation in the TrkA gene encoding the tyrosine kinase receptor for nerve growth factor (NGF) was previously documented in patients with congenital insensitivity to pain with anhidrosis (CIPA). These patients suffer from skin lacerations which often evolve into deep tissue infections. Abnormality in neutrophil functions may explain this high rate of severe infections. In this study we show that chemotaxis was significantly (P<0.001) suppressed in patients' neutrophils, compared to healthy controls. Although NGF alone did not exert a chemotactic effect, its presence enhanced both migration toward fMLP and phosphorylation of MAP kinases (ERK and JNK) in neutrophils from healthy controls, but not in neutrophils from CIPA patients. The significantly impaired chemotactic activity of neutrophils from a CIPA patient, which has been attributed to the molecular defect in the TrkA receptor, may contribute to the high rate of infection.

  5. Preliminary studies on the chemotactic potential of dogfish (Scyliorhinus canicula) leucocytes using the bipolar shape formation assay.

    PubMed

    Hunt, T C; Rowley, A F

    1986-06-01

    The bipolar shape formation assay, previously used to determine the chemotactic potential of various factors for mammalian leucocytes, was tested in the present study with granulocytes of the lesser spotted dogfish, Scyliorhinus canicula. Bipolar shape formation was found to be a temperature dependent process with maximal formation observed at 30 degrees C. Addition of the formyl peptide, N-formyl-methionyl-phenylalanine failed to induce any bipolar forms at all temperatures and concentrations tested.

  6. Developmental changes in chemotactic response and choice of two attractants, sodium acetate and diacetyl, in the nematode Caenorhabditis elegans.

    PubMed

    Matsuura, Tetsuya; Endo, Seiko; Iwamoto, Rie; Takahashi, Hayato; Ichinose, Mitsuyuki

    2007-08-01

    The chemotactic behavior of the nematode Caenorhabditis elegans to chemical attractants, water-soluble sodium acetate and odorant diacetyl, was investigated using nematodes at various developmental stages to examine the effects of postembryonic development on chemotactic response and spontaneous locomotion. The chemotactic responses to attractants increased as development progressed, and the largest responses to either 1.0 M sodium acetate or 0.1% diacetyl were seen at the young adult (YA) or day adult (A1) stage, respectively. Responses to the chemicals declined thereafter in-line with increasing age. The chemotaxis indices for attractants correlated with activity of spontaneous locomotion (p<0.01), suggesting that a change in spontaneous locomotion is one of the factors involved with the change in chemotactic responses during development. We also investigated the effect of aging on attractant choice by the simultaneous presentation of 0.6 M sodium acetate and 0.1% diacetyl. In the presence of both attractants, the fraction of larval animals at the sodium acetate location was greater than that at the diacetyl location (p<0.05). The fractions of YA animals that gathered at either location were almost identical, whereas the fraction of adult animals at the diacetyl location was greater than that at the sodium acetate location (p<0.05). The patterns of attractant choice of the long-lived daf-2 mutants and short lifespan mev-1 mutants showed the same tendency as those of wild type nematodes in the presence of both attractants. These results suggest that a change in the neuronal mechanisms controlling attractant choice and preference occurs during developmental progression.

  7. Gc-globulin (vitamin D-binding protein) enhances the neutrophil chemotactic activity of C5a and C5a des Arg.

    PubMed Central

    Kew, R R; Webster, R O

    1988-01-01

    Several serum proteins have been shown to be important in modulating leukocyte chemotaxis and inflammation. We investigated the possibility that the multifunctional serum protein Gc-globulin (vitamin D-binding protein) may also enhance the neutrophil chemotactic activity of complement-derived peptides. Purified Gc-globulin by itself did not induce chemotaxis of human neutrophils. However, as little as 0.01 nM Gc-globulin greatly enhanced the neutrophil chemotactic activity of C5a and its derivative, C5a des Arg over a wide concentration range. The effect was most pronounced at nonchemotactic doses of C5a (0.01 nM) and C5a des Arg (1 nM). Gc-globulin was unable to augment the neutrophil chemotactic activity of FMLP and leukotriene B4. This enhancing activity was not due to a nonspecific effect of anionic proteins since other purified serum proteins, of similar size and charge as Gc-globulin (alpha 1 acid glycoprotein, alpha 2 HS glycoprotein, alpha 2 histidine-rich glycoprotein), could not increase the chemotactic activity of C5a des Arg. Serum depleted of Gc-globulin by immunoaffinity chromatography totally lacked chemotactic enhancing activity for C5a des Arg. Gc-globulin-depleted serum activated with zymosan also had significantly less chemotactic activity than control- (sham-depleted) activated serum. Finally, radioiodinated C5a or C5a des Arg formed a 1:1 complex with purified Gc-globulin when analyzed by gel filtration chromatography. These results indicate that Gc-globulin is the major chemotactic enhancing factor in serum and may function as an up-regulator of the chemotactic activity of C5-derived peptides. PMID:3392213

  8. The Role of Glycerol and Inorganic Ions in Osmoregulatory Responses of the Euryhaline Flagellate Chlamydomonas pulsatilla Wollenweber 1

    PubMed Central

    Ahmad, Iftikhar; Hellebust, Johan A.

    1986-01-01

    The green euryhaline flagellate Chlamydomonas pulsatilla Wollenweber, isolated from a coastal marine environment, was grown exponentially over the salinity range of 10 to 200% artificial seawater (ASW). The cellular volume and aqueous space of the alga, measured by [14C] mannitol and 3H2O tracer analyses of centrifuged cell pellets, ranged between 2.3 and 3.1 picoliters and between 1.5 and 2.1 picoliters, respectively. The nonaqueous space determined in those analyses (28-35%) was consistent with the cell composition of the alga. The glycerol content of the alga increased almost linearly with increasing salinity; its contribution to intracellular osmolality at 200% ASW was about 57%. The contribution of amino acids and soluble carbohydrates to the cell osmotic balance was small. Intracellular ion concentrations determined by analyzing centrifuged cell pellets of known [14C]mannitol space by atomic absorption spectrophotometry, and by neutron activation analyses of washed cells were similar. At 10% ASW, potassium and magnesium were the major cations, and chloride and phosphate were the major anions. The sodium and chloride content of the alga increased with increasing salinity; at 200% ASW the intracellular concentration of both sodium and chloride was about 400 millimolar. The intracellular osmolality (πint) matched closely the external osmolality (πext) over the entire salinity range except at 10% ASW where πint exceeded πext by 120 to 270 milliosmoles per kilogram H2O. PMID:16665042

  9. Biogeography of heterotrophic flagellate populations indicates the presence of generalist and specialist taxa in the Arctic Ocean.

    PubMed

    Thaler, Mary; Lovejoy, Connie

    2015-03-01

    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.

  10. 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.

  11. [Chemotactic activity of neutrophils from atopic and non-atopic subjects--effect of sodium cromoglycate (DSCG)].

    PubMed

    Szkudlińska, B; Kowalski, M L; Grzegorczyk, J; Pierzchała, A

    1996-01-01

    It has been well documented, that sodium cromoglycate (DSCG) is capable in inhibiting activity of several inflammatory cells putatively involved in allergic and non-allergic asthmatic inflammation. The goal of this study was to compare the effect of DSCG on random locomotion and chemotaxis of neutrophils to several stimuli in atopic and non-atopic subjects. In 10 seasonal asthmatic (SA), and 10 healthy subjects (HS) chemotactic responses of neutrophils were examined using modified Boyden's microchamber (Neuroprobe) technique. Neutrophils isolated from both HS and SA demonstrated similar spontaneous migration and dose dependent chemotactic responses to FMLP (10(-12) - 10(-5M)), PAF (10(-7) - 10(-5M)) and ZAS (2.5% - 50%). DSCG in concentration range 10(-7) - 10(-9M) expressed a dose-dependent inhibition of both random migration and chemotactic responses to all stimuli tested, with maximal inhibition ranging from 58%-89% and 67%-75% for HS and SA, respectively. Our results confirm potent anti-inflammatory activity of DSCG in vitro, and demonstrate, that this activity is similar in atopic asthmatics, and in healthy subjects.

  12. Activation of cellular chemotactic responses to chemokines coupled with oxidation of plasma membrane proteins by lysyl oxidase.

    PubMed

    Lucero, Héctor A; Mäki, Joni M; Kagan, Herbert M

    2011-07-01

    Lysyl oxidase (LOX) is a potent chemokine inducing the migration of varied cell types. Here we demonstrate that inhibition of cellular LOX activity by preincubation of vascular smooth muscle cells (VSMC) with β-aminopropionitrile (BAPN), the irreversible inhibitor of LOX activity, resulted in the marked suppression of the chemotactic response and sensitivity of these cells toward LOX and toward PDGF-BB. Plasma membranes purified from VSMC not previously exposed to BAPN contained a group of oxidized plasma membrane proteins, including the PDGF receptor, PDGFR-β. The oxidation of this receptor and other membrane proteins was largely prevented in cells preincubated with BAPN. Addition of purified LOX to BAPN-free cells, which had been previously exposed to BAPN, restored the profile of oxidized proteins towards that of control cells. The high affinity and capacity for the binding of PDGF-BB by cells was significantly diminished when compared with cells in which oxidation by LOX was prevented by BAPN. The chemotactic responses of LOX knock-out mouse embryonic fibroblasts mirrored those obtained with VSMC treated with BAPN. These novel findings suggest that LOX activity is essential to generate optimal chemotactic sensitivity of cells to chemoattractants by oxidizing specific cell surface proteins, such as PDGFR-β.

  13. Comamonas testosteroni uses a chemoreceptor for tricarboxylic acid cycle intermediates to trigger chemotactic responses towards aromatic compounds.

    PubMed

    Ni, Bin; Huang, Zhou; Fan, Zheng; Jiang, Cheng-Ying; Liu, Shuang-Jiang

    2013-11-01

    Bacterial chemotaxis towards aromatic compounds has been frequently observed; however, knowledge of how bacteria sense aromatic compounds is limited. Comamonas testosteroni CNB-1 is able to grow on a range of aromatic compounds. This study investigated the chemotactic responses of CNB-1 to 10 aromatic compounds. We constructed a chemoreceptor-free, non-chemotactic mutant, CNB-1Δ20, by disruption of all 19 putative methyl-accepting chemotaxis proteins (MCPs) and the atypical chemoreceptor in strain CNB-1. Individual complementation revealed that a putative MCP (tagged MCP2201) was involved in triggering chemotaxis towards all 10 aromatic compounds. The recombinant sensory domain of MCP2201 did not bind to 3- or 4-hydroxybenzoate, protocatechuate, catechol, benzoate, vanillate and gentisate, but bound oxaloacetate, citrate, cis-aconitate, isocitrate, α-ketoglutarate, succinate, fumarate and malate. The mutant CNB-1ΔpmdF that lost the ability to metabolize 4-hydroxybenzoate and protocatechuate also lost its chemotactic response to these compounds, suggesting that taxis towards aromatic compounds is metabolism-dependent. Based on the ligand profile, we proposed that MCP2201 triggers taxis towards aromatic compounds by sensing TCA cycle intermediates. Our hypothesis was further supported by the finding that introduction of the previously characterized pseudomonad chemoreceptor (McpS) for TCA cycle intermediates into CNB-1Δ20 likewise triggered chemotaxis towards aromatic compounds.

  14. Phytosphingosine-1-phosphate stimulates chemotactic migration of L2071 mouse fibroblasts via pertussis toxin-sensitive G-proteins.

    PubMed

    Kim, Mi-Kyoung; Park, Kyoung Sun; Lee, Hyuck; Kim, Young Dae; Yun, Jeanho; Bae, Yoe-Sik

    2007-04-30

    Phytosphingosine-1-phosphate (PhS1P) was found to stimulate an intracellular calcium increase via phospholipase C but not pertussis toxin (PTX)-sensitive G-proteins in L2071 mouse fibroblasts. PhS1P also activated ERK and p38 kinase, and these activations by PhS1P were inhibited by PTX. Moreover, PhS1P stimulated the chemotactic migration of L2071 cells via PTX-sensitive Gi protein(s). In addition, the PhS1P-induced chemotactic migration of L2071 cells was also dramatically inhibited by LY294002 and SB203580 (inhibitors of phosphoinositide 3-kinase and p38 kinase, respectively). L2071 cells are known to express four S1P receptors, i.e., S1P1, S1P2, S1P3, and S1P4, and pretreatment with an S1P1 and S1P3 antagonist (VPC 23019) did not affect on PhS1P-induced chemotaxis. This study demonstrates that PhS1P stimulates at least two different signaling cascades, one is a PTX-insensitive but phospholipase C dependent intracellular calcium increase, and the other is a PTX-sensitive chemotactic migration mediated by phosphoinositide 3-kinase and p38 kinase.

  15. Homing of hemopoietic precursor cells to the embryonic thymus: characterization of an invasive mechanism induced by chemotactic peptides

    PubMed Central

    1986-01-01

    During embryonic development, T cell precursors migrate to the thymus, where immunocompetency is acquired. Our previous studies have shown that avian hemopoietic precursor cells are recruited to the thymus by chemotactic peptides secreted by thymic epithelial cells (Champion, S., B. A. Imhof, P. Savagner, and J. P. Thiery, 1986, Cell, 44:781-790). In this study, we have characterized the homing of these precursor cells to the thymus in vivo by electron and light microscopy. Hemopoietic precursors could be seen to extravasate from blood or lymphatic vessels, migrate in the mesenchyme, traverse the perithymic basement membrane, and finally intercalate into the thymic epithelium. Labeled hemopoietic precursors injected into the blood circulation also followed the same pathway. Migrating hemopoietic precursor cells were found to express the fibronectin receptor complex. In the presence of thymic chemotactic peptides, hemopoietic precursors traverse a human amniotic basement membrane. This invasive process was inhibited by antibodies to laminin or to fibronectin, two major glycoproteins of the amniotic membrane, by monovalent Fab' fragments of antibodies to the fibronectin receptor, and, finally by synthetic peptides that contain the cell-binding sequence Arg-Gly-Asp-Ser of fibronectin. These results indicate that hemopoietic precursors respond to thymic chemotactic peptides by invasive behavior. Direct interactions between basement membrane components and fibronectin receptors appear to be required for this developmentally regulated invasion process. PMID:3793754

  16. The HIV-1 gp41 ectodomain is cleaved by matriptase to produce a chemotactic peptide that acts through FPR2.

    PubMed

    Wood, Matthew P; Cole, Amy L; Eade, Colleen R; Chen, Li-Mei; Chai, Karl X; Cole, Alexander M

    2014-07-01

    Several aspects of HIV-1 virulence and pathogenesis are mediated by the envelope protein gp41. Additionally, peptides derived from the gp41 ectodomain have been shown to induce chemotaxis in monocytes and neutrophils. Whereas this chemotactic activity has been reported, it is not known how these peptides could be produced under biological conditions. The heptad repeat 1 (HR1) region of gp41 is exposed to the extracellular environment and could therefore be susceptible to proteolytic processing into smaller peptides. Matriptase is a serine protease expressed at the surface of most epithelia, including the prostate and mucosal surfaces. Here, we present evidence that matriptase efficiently cleaves the HR1 portion of gp41 into a 22-residue chemotactic peptide MAT-1, the sequence of which is highly conserved across HIV-1 clades. We found that MAT-1 induced migration of primary neutrophils and monocytes, the latter of which act as a cellular reservoir of HIV during early stage infection. We then used formyl peptide receptor 1 (FPR1) and FPR2 inhibitors, along with HEK 293 cells, to demonstrate that MAT-1 can induce chemotaxis specifically using FPR2, a receptor found on the surface of monocytes, macrophages and neutrophils. These findings are the first to identify a proteolytic cleavage product of gp41 with chemotactic activity and highlight a potential role for matriptase in HIV-1 transmission and infection at epithelial surfaces and within tissue reservoirs of HIV-1.

  17. Recombinant gamma interferon causes neutrophil migration mediated by the release of a macrophage neutrophil chemotactic factor.

    PubMed Central

    Ribeiro, R. A.; Cunha, F. Q.; Ferreira, S. H.

    1990-01-01

    A dose-dependent neutrophil migration was observed following the injection of purified (Hu IFN-gamma) or recombinant (rIFN-gamma) human gamma interferon into rat peritoneal cavities. This finding contrasts with their inability to cause chemotaxis in vitro in the Boyden chamber. Neutrophil migration into peritoneal cavities and subcutaneous air pouches induced by both preparations of interferon was abolished by pretreatment of the animals with dexamethasone. IFN-gamma-induced neutrophil migration was enhanced when the macrophage population of the peritoneal cavities was increased by previous injection of thioglycollate and reduced by peritoneal lavage. Macrophage monolayers pretreated either with rIFN-gamma or with lipopolysaccharide from E. coli release into the supernatant a factor that stimulates neutrophil recruitment in animals treated with dexamethasone. Dexamethasone blocked this release but did not affect the neutrophil recruitment induced by this factor. These results suggest that IFN-gamma-induced neutrophil migration in vivo may be mediated by the release from resident macrophages of a neutrophil chemotactic factor and that dexamethasone blockade of neutrophil recruitment by IFN-gamma is due to inhibition of the release of this factor. PMID:2119790

  18. Monocyte chemotactic protein-1 and other inflammatory parameters in Bernese Mountain dogs with disseminated histiocytic sarcoma.

    PubMed

    Nikolic Nielsen, Lise; Kjelgaard-Hansen, Mads; Kristensen, Annemarie T

    2013-11-01

    The interaction between cancer and the immune system, and the production of cytokines by the tumour itself have been associated with altered levels of cytokines in human cancer patients. Bernese Mountain dogs with disseminated histiocytic sarcoma (DHS) show vague and non-specific clinical signs. Although histiocytes can secrete cytokines in response to inflammatory stimuli, serum cytokine concentrations in dogs with DHS have not previously been investigated. The aim of this study was to evaluate the immunological state of untreated Bernese Mountain dogs with DHS by assessing multiple serum cytokines and to correlate these with other inflammatory markers. As a prospective case control study, 17 Bernese Mountain dogs with DHS were included along with 18 healthy controls (12 Bernese Mountain dogs and 6 dogs of various breeds). Blood samples were examined for fibrinogen, C-reactive protein (CRP), white blood cell count, monocyte count and the following cytokines: interleukin (IL)-6, IL-10, IL-12, IL-15, IL-18, tumour necrosis factor and monocyte chemotactic protein (MCP)-1. Significant differences were observed in Bernese Mountain dogs with DHS compared to healthy control dogs for fibrinogen (P=0.002), CRP (P=0.02) and MCP-1 (P=0.004). Other important pro-inflammatory cytokines were not significantly increased in dogs with DHS and none of the measured cytokines were correlated to either WBC, monocyte count, CRP or fibrinogen concentration. The implications of this increased MCP-1 blood levels in Bernese Mountain dogs with DHS warrant further investigations.

  19. Anti-coreceptor therapy drives selective T cell egress by suppressing inflammation-dependent chemotactic cues

    PubMed Central

    Martin, Aaron J.; Clark, Matthew; Gojanovich, Gregory; Manzoor, Fatima; Miller, Keith; Kline, Douglas E.; Morillon, Y. Maurice; Wang, Bo

    2016-01-01

    There continues to be a need for immunotherapies to treat type 1 diabetes in the clinic. We previously reported that nondepleting anti-CD4 and -CD8 Ab treatment effectively reverses diabetes in new-onset NOD mice. A key feature of the induction of remission is the egress of the majority of islet-resident T cells. How this occurs is undefined. Herein, the effects of coreceptor therapy on islet T cell retention were investigated. Bivalent Ab binding to CD4 and CD8 blocked TCR signaling and T cell cytokine production, while indirectly downregulating islet chemokine expression. These processes were required for T cell retention, as ectopic IFN-γ or CXCL10 inhibited Ab-mediated T cell purging. Importantly, treatment of humanized mice with nondepleting anti–human CD4 and CD8 Ab similarly reduced tissue-infiltrating human CD4+ and CD8+ T cells. These findings demonstrate that Ab binding of CD4 and CD8 interrupts a feed-forward circuit by suppressing T cell–produced cytokines needed for expression of chemotactic cues, leading to rapid T cell egress from the islets. Coreceptor therapy therefore offers a robust approach to suppress T cell–mediated pathology by purging T cells in an inflammation-dependent manner. PMID:27777971

  20. 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

  1. NLRP3 inflammasome induces chemotactic immune cell migration to the CNS in experimental autoimmune encephalomyelitis

    PubMed Central

    Inoue, Makoto; Williams, Kristi L.; Gunn, Michael D.; Shinohara, Mari L.

    2012-01-01

    The NLRP3 inflammasome is a multiprotein complex consisting of three kinds of proteins, NLRP3, ASC, and pro-caspase-1, and plays a role in sensing pathogens and danger signals in the innate immune system. The NLRP3 inflammasome is thought to be involved in the development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). However, the mechanism by which the NLRP3 inflammasome induces EAE is not clear. In this study, we found that the NLRP3 inflammasome played a critical role in inducing T-helper cell migration into the CNS. To gain migratory ability, CD4+ T cells need to be primed by NLRP3 inflammasome-sufficient antigen-presenting cells to up-regulate chemotaxis-related proteins, such as osteopontin, CCR2, and CXCR6. In the presence of the NLRP3 inflammasome, dendritic cells and macrophages also induce chemotactic ability and up-regulate chemotaxis-related proteins, such as α4β1 integrin, CCL7, CCL8, and CXCL16. On the other hand, reduced Th17 cell population size in immunized Nlrp3−/− and Asc−/− mice is not a determinative factor for their resistance to EAE. As currently applied in clinical interventions of MS, targeting immune cell migration molecules may be an effective approach in treating MS accompanied by NLRP3 inflammasome activation. PMID:22699511

  2. Differential Localization of Chemotactic Signaling Arrays during the Lifecycle of Vibrio parahaemolyticus

    PubMed Central

    Heering, Jan; Ringgaard, Simon

    2016-01-01

    When encountering new environments or changes to their external milieu, bacteria use elaborate mechanisms to respond accordingly. Here, we describe how Vibrio parahaemolyticus coordinates two such mechanisms – differentiation and chemotaxis. V. parahaemolyticus differentiates between two distinct cell types: short rod-shaped swimmer cells and highly elongated swarmer cells. We show that the intracellular organization of chemotactic signaling arrays changes according to the differentiation state. In swimmer cells chemotaxis arrays are strictly polarly localized, but in swarmer cells arrays form both at the cell poles and at irregular intervals along the entire cell length. Furthermore, the formation of lateral arrays increases with cell length of swarmer cells. Occurrence of lateral signaling arrays is not simply a consequence of the elongated state of swarmer cells, but is instead differentiation state-specific. Moreover, our data suggest that swarmer cells employ two distinct mechanisms for localization of polar and lateral signaling arrays, respectively. Furthermore, cells show a distinct differentiation and localization pattern of chemosensory arrays, depending on their location within swarm colonies, which likely allows for the organism to simultaneously swarm across surfaces while sustaining a pool of swimmers immediately capable of exploring new liquid surroundings. PMID:27853457

  3. Theoretical results for chemotactic response and drift of E. coli in a weak attractant gradient.

    PubMed

    Reneaux, Melissa; Gopalakrishnan, Manoj

    2010-09-07

    The bacterium Escherichia coli (E. coli) moves in its natural environment in a series of straight runs, interrupted by tumbles which cause change of direction. It performs chemotaxis towards chemo-attractants by extending the duration of runs in the direction of the source. When there is a spatial gradient in the attractant concentration, this bias produces a drift velocity directed towards its source, whereas in a uniform concentration, E. coli adapts, almost perfectly in case of methyl aspartate. Recently, microfluidic experiments have measured the drift velocity of E. coli in precisely controlled attractant gradients, but no general theoretical expression for the same exists. With this motivation, we study an analytically soluble model here, based on the Barkai-Leibler model, originally introduced to explain the perfect adaptation. Rigorous mathematical expressions are obtained for the chemotactic response function and the drift velocity in the limit of weak gradients and under the assumption of completely random tumbles. The theoretical predictions compare favorably with experimental results, especially at high concentrations. We further show that the signal transduction network weakens the dependence of the drift on concentration, thus enhancing the range of sensitivity.

  4. 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.

  5. 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.

  6. Neutrophil chemotactic factor (IL-8) gene expression by cytokine-treated retinal pigment epithelial cells.

    PubMed Central

    Elner, V. M.; Strieter, R. M.; Elner, S. G.; Baggiolini, M.; Lindley, I.; Kunkel, S. L.

    1990-01-01

    The neural-derived retinal pigment epithelium (RPE) underlies the sensory retina and is central to both retinal homeostasis and many common retinal diseases. Retinal pigment epithelium cells are actively phagocytic and share several features with macrophages that have recently been shown to produce a neutrophil chemotactic factor (NCF), also known as interleukin-8, after cytokine stimulation. Because RPE cell responses to cytokines are largely unknown, human RPE cell NCF production was monitored after interleukin-1-beta (IL-1 beta), tumor necrosis factor-alpha, or lipopolysaccharide stimulation. RPE NCF mRNA expression and RPE production of biologically active NCF was time and concentration dependent. Maximal NCF mRNA expression occurred at 20 ng/ml for IL-1 beta. Messenger RNA expression in RPE cells and biologically active NCF in RPE cell supernatants were found 1 hour after stimulation and were maintained for 24 hours. These findings demonstrate that cytokine-stimulated RPE cells may evoke or augment neutrophil-mediated inflammation by synthesizing NCF, a cytokine that may be important in ocular disease mechanisms. Images Figure 1 Figure 3 PMID:2183623

  7. A microfluidic imaging chamber for the direct observation of chemotactic transmigration

    PubMed Central

    Breckenridge, Mark T.; Egelhoff, Thomas T.; Baskaran, Harihara

    2010-01-01

    To study the roles of nonmuscle myosin II (NM-II) during invasive cell migration, microfluidic migration chambers have been designed and fabricated using photo- and soft-lithography microfabrication techniques. The chamber consists of two channels separated by a vertical barrier with multiple bays of pores with widths varying from 6 µm to 16 µm, and lengths varying from 25µm to 50µm. The cells are plated in the channel on one side of the barrier while a chemoattractant is flowed through the channel on the other side of the barrier. In these chambers, cells can be observed with transmitted light or fluorescence optics while they chemotax through various sized pores that impose differential mechanical resistance to transmigration. As an initial test of this device, we compared breast-cancer cell chemotactic transmigration through different pore sizes with and without inhibition of NM-II. Two distinct rates were observed as cells attempted to pull their nucleus through the smaller pores, and the faster nuclear transit mode was critically dependent on NM-II motor activity. The ability to monitor cells as they chemotax through pores of different dimensions within a single experimental system provides novel information on how pore size affects cell morphology and migration rate, providing a dramatic improvement of imaging potential relative to other in vitro transmigration systems such as Boyden chambers. PMID:20309736

  8. 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).

  9. Chemotactic systems in the presence of conflicts: A new functional inequality

    NASA Astrophysics Data System (ADS)

    Wolansky, G.

    2016-11-01

    The evolution of a chemotactic system involving a population of cells attracted to self-produced chemicals is described by the Keller-Segel system. In dimension 2, this system demonstrates a balance between the spreading effect of diffusion and the concentration due to self-attraction. As a result, there exists a critical "mass" (i.e. total cell's population) above which the solution of this system collapses in a finite time, while below this critical mass there is global existence in time. In particular, subcritical mass leads under certain additional conditions to the existence of steady states, corresponding to the solution of an elliptic Liouville equation. The existence of this critical mass is related to a functional inequality known as the Moser-Trudinger inequality. An extension of the Keller-Segel model to several cells populations was considered before in the literature. Here we review some of these results and, in particular, consider the case of conflict between two populations, that is, when population one attracts population two, while, at the same time, population two repels population one. This assumption leads to a new functional inequality which generalizes the Moser-Trudinger inequality. As an application of this inequality we derive sufficient conditions for the existence of steady states corresponding to solutions of an elliptic Liouville system.

  10. 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

  11. Directional memory arises from long-lived cytoskeletal asymmetries in polarized chemotactic cells.

    PubMed

    Prentice-Mott, Harrison V; Meroz, Yasmine; Carlson, Andreas; Levine, Michael A; Davidson, Michael W; Irimia, Daniel; Charras, Guillaume T; Mahadevan, L; Shah, Jagesh V

    2016-02-02

    Chemotaxis, the directional migration of cells in a chemical gradient, is robust to fluctuations associated with low chemical concentrations and dynamically changing gradients as well as high saturating chemical concentrations. Although a number of reports have identified cellular behavior consistent with a directional memory that could account for behavior in these complex environments, the quantitative and molecular details of such a memory process remain unknown. Using microfluidics to confine cellular motion to a 1D channel and control chemoattractant exposure, we observed directional memory in chemotactic neutrophil-like cells. We modeled this directional memory as a long-lived intracellular asymmetry that decays slower than observed membrane phospholipid signaling. Measurements of intracellular dynamics revealed that moesin at the cell rear is a long-lived element that when inhibited, results in a reduction of memory. Inhibition of ROCK (Rho-associated protein kinase), downstream of RhoA (Ras homolog gene family, member A), stabilized moesin and directional memory while depolymerization of microtubules (MTs) disoriented moesin deposition and also reduced directional memory. Our study reveals that long-lived polarized cytoskeletal structures, specifically moesin, actomyosin, and MTs, provide a directional memory in neutrophil-like cells even as they respond on short time scales to external chemical cues.

  12. Squid-derived chitin oligosaccharides are a chemotactic signal during colonization by Vibrio fischeri.

    PubMed

    Mandel, Mark J; Schaefer, Amy L; Brennan, Caitlin A; Heath-Heckman, Elizabeth A C; Deloney-Marino, Cindy R; McFall-Ngai, Margaret J; Ruby, Edward G

    2012-07-01

    Chitin, a polymer of N-acetylglucosamine (GlcNAc), is noted as the second most abundant biopolymer in nature. Chitin serves many functions for marine bacteria in the family Vibrionaceae ("vibrios"), in some instances providing a physical attachment site, inducing natural genetic competence, and serving as an attractant for chemotaxis. The marine luminous bacterium Vibrio fischeri is the specific symbiont in the light-emitting organ of the Hawaiian bobtail squid, Euprymna scolopes. The bacterium provides the squid with luminescence that the animal uses in an antipredatory defense, while the squid supports the symbiont's nutritional requirements. V. fischeri cells are harvested from seawater during each host generation, and V. fischeri is the only species that can complete this process in nature. Furthermore, chitin is located in squid hemocytes and plays a nutritional role in the symbiosis. We demonstrate here that chitin oligosaccharides produced by the squid host serve as a chemotactic signal for colonizing bacteria. V. fischeri uses the gradient of host chitin to enter the squid light organ duct and colonize the animal. We provide evidence that chitin serves a novel function in an animal-bacterial mutualism, as an animal-produced bacterium-attracting synomone.

  13. Monocyte Chemotactic Protein-1 Regulates Voltage-Gated K+ Channels and Macrophage Transmigration

    PubMed Central

    Gendelman, Howard E.; Ding, Shengyuan; Gong, Nan; Liu, Jianuo; Ramirez, Servio H.; Persidsky, Yuri; Mosley, R. Lee; Wang, Tong; Volsky, David J.; Xiong, Huangui

    2009-01-01

    Progressive human immunodeficiency virus (HIV)-1 infection and virus-induced neuroinflammatory responses effectuates monocyte-macrophage transmigration across the blood-brain barrier (BBB). A key factor in mediating these events is monocyte chemotactic protein-1 (MCP-1). Upregulated glial-derived MCP-1 in HIV-1 infected brain tissues generates a gradient for monocyte recruitment into the nervous system. We posit that the inter-relationships between MCP-1, voltage gated ion channels, cell shape and volume, and cell mobility underlie monocyte transmigration across the BBB. In this regard, MCP-1 serves both as a chemoattractant and an inducer of monocyte-macrophage ion flux affecting cell shape and mobility. To address this hypothesis, MCP-1 treated bone marrow derived macrophages (BMM) were analyzed for gene and protein expression, electrophysiology, and capacity to migrate across a laboratory constructed BBB. MCP-1 enhanced K+ channel gene (KCNA3) and channel protein expression. Electrophysiological studies revealed that MCP-1 increased outward K+ currents in a dose dependent manner. In vitro studies demonstrated that MCP-1 increased BMM migration across an artificial BBB and the MCP-1-induced BMM migration was blocked by tetraethylammonium, a voltage-gated K+ channel blocker. Together these data demonstrated that MCP-1 affects macrophage migratory movement through regulation of voltage-gated K+ channels and as such, provides a novel therapeutic strategy for neuroAIDS PMID:19034671

  14. Transient receptor potential canonical channels are essential for chemotactic migration of human malignant gliomas.

    PubMed

    Bomben, Valerie C; Turner, Kathryn L; Barclay, Tia-Tabitha C; Sontheimer, Harald

    2011-07-01

    The majority of malignant primary brain tumors are gliomas, derived from glial cells. Grade IV gliomas, Glioblastoma multiforme, are extremely invasive and the clinical prognosis for patients is dismal. Gliomas utilize a number of proteins and pathways to infiltrate the brain parenchyma including ion channels and calcium signaling pathways. In this study, we investigated the localization and functional relevance of transient receptor potential canonical (TRPC) channels in glioma migration. We show that gliomas are attracted in a chemotactic manner to epidermal growth factor (EGF). Stimulation with EGF results in TRPC1 channel localization to the leading edge of migrating D54MG glioma cells. Additionally, TRPC1 channels co-localize with the lipid raft proteins, caveolin-1 and β-cholera toxin, and biochemical assays show TRPC1 in the caveolar raft fraction of the membrane. Chemotaxis toward EGF was lost when TRPC channels were pharmacologically inhibited or by shRNA knockdown of TRPC1 channels, yet without affecting unstimulated cell motility. Moreover, lipid raft integrity was required for gliomas chemotaxis. Disruption of lipid rafts not only impaired chemotaxis but also impaired TRPC currents in whole cell recordings and decreased store-operated calcium entry as revealed by ratiomeric calcium imaging. These data indicated that TRPC1 channel association with lipid rafts is essential for glioma chemotaxis in response to stimuli, such as EGF.

  15. A chemotactic gradient sequestered on endothelial heparan sulfate induces directional intraluminal crawling of neutrophils.

    PubMed

    Massena, Sara; Christoffersson, Gustaf; Hjertström, Elina; Zcharia, Eyal; Vlodavsky, Israel; Ausmees, Nora; Rolny, Charlotte; Li, Jin-Ping; Phillipson, Mia

    2010-09-16

    During infection, chemokines sequestered on endothelium induce recruitment of circulating leukocytes into the tissue where they chemotax along chemokine gradients toward the afflicted site. The aim of this in vivo study was to determine whether a chemokine gradient was formed intravascularly and influenced intraluminal neutrophil crawling and transmigration. A chemokine gradient was induced by placing a macrophage inflammatory protein-2 (MIP-2)-containing (CXCL2) gel on the cremaster muscle of anesthetized wild-type mice or heparanase-overexpressing transgenic mice (hpa-tg) with truncated heparan sulfate (HS) side chains. Neutrophil-endothelial interactions were visualized by intravital microscopy and chemokine gradients detected by confocal microscopy. Localized extravascular chemokine release (MIP-2 gel) induced directed neutrophil crawling along a chemotactic gradient immobilized on the endothelium and accelerated their recruitment into the target tissue compared with homogeneous extravascular chemokine concentration (MIP-2 superfusion). Endothelial chemokine sequestration occurred exclusively in venules and was HS-dependent, and neutrophils in hpa-tg mice exhibited random crawling. Despite similar numbers of adherent neutrophils in hpa-tg and wild-type mice, the altered crawling in hpa-tg mice was translated into decreased number of emigrated neutrophils and ultimately decreased the ability to clear bacterial infections. In conclusion, an intravascular chemokine gradient sequestered by endothelial HS effectively directs crawling leukocytes toward transmigration loci close to the infection site.

  16. 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

  17. Inferring the Chemotactic Strategy of P. putida and E. coli Using Modified Kramers-Moyal Coefficients

    PubMed Central

    Hintsche, Marius; Beta, Carsten; Stark, Holger

    2017-01-01

    Many bacteria perform a run-and-tumble random walk to explore their surrounding and to perform chemotaxis. In this article we present a novel method to infer the relevant parameters of bacterial motion from experimental trajectories including the tumbling events. We introduce a stochastic model for the orientation angle, where a shot-noise process initiates tumbles, and analytically calculate conditional moments, reminiscent of Kramers-Moyal coefficients. Matching them with the moments calculated from experimental trajectories of the bacteria E. coli and Pseudomonas putida, we are able to infer their respective tumble rates, the rotational diffusion constants, and the distributions of tumble angles in good agreement with results from conventional tumble recognizers. We also define a novel tumble recognizer, which explicitly quantifies the error in recognizing tumbles. In the presence of a chemical gradient we condition the moments on the bacterial direction of motion and thereby explore the chemotaxis strategy. For both bacteria we recover and quantify the classical chemotactic strategy, where the tumble rate is smallest along the chemical gradient. In addition, for E. coli we detect some cells, which bias their mean tumble angle towards smaller values. Our findings are supported by a scaling analysis of appropriate ratios of conditional moments, which are directly calculated from experimental data. PMID:28114420

  18. 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.

  19. Investigations into the design principles in the chemotactic behavior of Escherichia coli.

    PubMed

    Kim, Tae-Hwan; Jung, Sung Hoon; Cho, Kwang-Hyun

    2008-01-01

    Inspired by the recent studies on the analysis of biased random walk behavior of Escherichia coli[Passino, K.M., 2002. Biomimicry of bacterial foraging for distributed optimization and control. IEEE Control Syst. Mag. 22 (3), 52-67; Passino, K.M., 2005. Biomimicry for Optimization, Control and Automation. Springer-Verlag, pp. 768-798; Liu, Y., Passino, K.M., 2002. Biomimicry of social foraging bacteria for distributed optimization: models, principles, and emergent behaviors. J. Optim. Theory Appl. 115 (3), 603-628], we have developed a model describing the motile behavior of E. coli by specifying some simple rules on the chemotaxis. Based on this model, we have analyzed the role of some key parameters involved in the chemotactic behavior to unravel the underlying design principles. By investigating the target tracking capability of E. coli in a maze through computer simulations, we found that E. coli clusters can be controlled as target trackers in a complex micro-scale-environment. In addition, we have explored the dynamical characteristics of this target tracking mechanism through perturbation of parameters under noisy environments. It turns out that the E. coli chemotaxis mechanism might be designed such that it is sensitive enough to efficiently track the target and also robust enough to overcome environmental noises.

  20. Caffeine, dibutyryl cyclic-AMP and heparin affect the chemotactic and phagocytotic activities of neutrophils for boar sperm in vitro.

    PubMed

    Li, J-C; Yamaguchi, S; Kondo, Y; Funahashi, H

    2011-04-15

    The objective was to examine the effects of caffeine, dibutyryl cyclic AMP, and heparin on the chemotaxis and/or phagocytosis of PMNs for porcine sperm. The chemotactic activity of PMNs, determined in a blind well chamber, increased (P < 0.05) when fresh serum was added to the medium (control containing BSA, 1109.5 cells/mm(2) vs serum, 1226.3 cells/mm(2)), regardless of the presence of sperm (control, 1121.1 cells/mm(2) vs serum, 1245.8 cells/mm(2)), whereas heat-inactivated serum did not affect activity (without sperm, 1099.4 cells/mm(2) and with sperm, 1132.6 cells/mm(2)). Regardless of live and dead sperm and of the origin of PMNs (boars vs sows), the phagocytotic activity of PMNs, as determined by co-culture of PMNs with sperm for 60 min, increased (P < 0.05) in the presence of fresh serum containing active complement (46.7 and 43.0%, respectively), but stimulation was decreased (P < 0.05) when 1 mM or higher concentrations of caffeine was added to the medium (from 40.7 to 20.8-31.6%). The origin of PMNs (sows vs boars) did not significantly affect phagocytotic activity. The percentage of PMNs that phagocytized polystyrene latex beads decreased when 2 mM caffeine was added to the medium containing porcine serum (from 43.7 to 21.5%). Serum-stimulated chemotactic activity of PMNs (1089.9 cells/mm(2)) was also reduced (P < 0.05) with 2 mM caffeine (942.5 cells/mm(2)). Furthermore, dibutyryl cAMP at ≥ 0.1 mM or heparin at ≥ 100 μg/mL decreased phagocytotic activity, in a concentration-dependent manner (P < 0.05). Supplementation of PMNs with heparin at 100 or 500 μg/mL decreased (P < 0.05) chemotactic activity in the presence of serum (from 1137.1 cells/mm(2) to 1008.8-1026.3 cells/mm(2)). We inferred that opsonization in the presence of active complement stimulated phagocytotic and chemotactic activities of PMNs, whereas supplementation with caffeine and dibutyryl cAMP (which could be associated with the intracellular cAMP level of PMNs) or adding heparin

  1. 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.

  2. A novel biologic activity of thrombin: stimulation of monocyte chemotactic protein production

    PubMed Central

    1994-01-01

    Thrombin is a serine protease that is released at sites of vascular injury and exerts a variety of biologic effects on different cell types. Thrombin is postulated to play a role in the pathogenesis of a number of diseases including atherosclerosis, since it activates vascular smooth muscle and endothelial cells. Thrombin mediates these effects through a specific receptor that is upregulated in vascular cells in atherosclerosis. Atherosclerosis and glomerulosclerosis are characterized by the presence of monocyte-macrophages in the lesions. Monocyte chemotactic protein (MCP-1) is believed to be an important mediator of monocyte recruitment to the tissue and can be induced in a broad variety of cells including mesangial cells. We studied the effect of thrombin on MCP-1 production and gene expression in well- characterized human mesangial cells, vascular pericytes that play a central role in fibrosis of the glomerular microvascular bed. alpha thrombin stimulates MCP-1 production and gene expression in mesangial cells in a dose- and time-dependent manner. Experiments with diisopropylfluorophosphate thrombin and gamma thrombin demonstrate that this thrombin effect requires both receptor binding as well as catalytic activity, features consistent with the known properties of the recently characterized and cloned thrombin receptor. Moreover, a human thrombin receptor activating peptide (TRAP1-7) also stimulates MCP-1 production. Northern blot analysis demonstrated that mesangial cells express an mRNA transcript that hybridizes with labeled human thrombin receptor cDNA. These data describe a novel biologic activity of thrombin and suggest an additional mechanism by which this coagulation factor may participate in the progression of glomerulosclerosis, and by analogy, atherosclerosis. PMID:8163952

  3. 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.

  4. 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

  5. Mytilus galloprovincialis Myticin C: A Chemotactic Molecule with Antiviral Activity and Immunoregulatory Properties

    PubMed Central

    Romero, Alejandro; Dios, Sonia; Martínez-López, Alicia; Figueras, Antonio; Estepa, Amparo; Novoa, Beatriz

    2011-01-01

    Previous research has shown that an antimicrobial peptide (AMP) of the myticin class C (Myt C) is the most abundantly expressed gene in cDNA and suppressive subtractive hybridization (SSH) libraries after immune stimulation of mussel Mytilus galloprovincialis. However, to date, the expression pattern, the antimicrobial activities and the immunomodulatory properties of the Myt C peptide have not been determined. In contrast, it is known that Myt C mRNA presents an unusual and high level of polymorphism of unidentified biological significance. Therefore, to provide a better understanding of the features of this interesting molecule, we have investigated its function using four different cloned and expressed variants of Myt C cDNA and polyclonal anti-Myt C sera. The in vivo results suggest that this AMP, mainly present in hemocytes, could be acting as an immune system modulator molecule because its overexpression was able to alter the expression of mussel immune-related genes (as the antimicrobial peptides Myticin B and Mytilin B, the C1q domain-containing protein MgC1q, and lysozyme). Moreover, the in vitro results indicate that Myt C peptides have antimicrobial and chemotactic properties. Their recombinant expression in a fish cell line conferred protection against two different fish viruses (enveloped and non-enveloped). Cell extracts from Myt C expressing fish cells were also able to attract hemocytes. All together, these results suggest that Myt C should be considered not only as an AMP but also as the first chemokine/cytokine-like molecule identified in bivalves and one of the few examples in all of the invertebrates. PMID:21858010

  6. Cytokines secreted by macrophages isolated from tumor microenvironment of inflammatory breast cancer patients possess chemotactic properties

    PubMed Central

    Mohamed, Mona M.; El-Ghonaimy, Eslam A.; Nouh, Mohamed A.; Schneider, Robert J.; Sloane, Bonnie F.; El-Shinawi, Mohamed

    2014-01-01

    Although there is a growing literature describing the role of macrophages in breast cancer, the role of macrophages in inflammatory breast cancer (IBC) is unclear. The aim of present study was to isolate and characterize tumor associated macrophages of IBC and non-IBC patients and define their role in IBC. Tumor infiltrating monocytes/macrophages (CD14+ and CD68+) were measured by immunohistochem-istry using specific monoclonal antibodies. Blood drained from axillary vein tributaries was collected during breast cancer surgery and the percentage of CD14+ in the total isolated leukocytes was assessed by flow cytometric analysis. CD14+ cells were separated from total leukocytes by immuno-magnetic beads technique and were cultured overnight. Media conditioned by CD14+ were collected and subjected to cytokine profiling using cytokine antibody array. Wound healing and invasion assays were used to test whether cytokines highly secreted by tumor drained macrophages induce motility and invasion of breast cancer cells. We found that macrophages highly infiltrate into carcinoma tissues of IBC patients. In addition blood collected from axillary tributaries of IBC patients is highly enriched with CD14+ cells as compared to blood collected from non-IBC patients. Cytokine profiling of CD14+ cells isolated from IBC patients revealed a significant increase in secretion of tumor necrosis factor-α; monocyte chemoat-tractant protein-1/CC-chemokine ligand 2; interleukin-8 and interleukin-10 as compared to CD14+ cells isolated from non-IBC patients. Tumor necrosis factor-a, interleukin-8 and interleukin-10 significantly increased motility and invasion of IBC cells in vitro. In conclusion, macrophages isolated from the tumor microenvironment of IBC patients secrete chemotactic cytokines that may augment dissemination and metastasis of IBC carcinoma cells. PMID:24291763

  7. Chemotactic Migration of T Cells towards Dendritic Cells Promotes the Detection of Rare Antigens

    PubMed Central

    Vroomans, Renske M. A.; Marée, Athanasius F. M.; de Boer, Rob J.; Beltman, Joost B.

    2012-01-01

    In many immunological processes chemoattraction is thought to play a role in guiding cells to their sites of action. However, based on in vivo two-photon microscopy experiments in the absence of cognate antigen, T cell migration in lymph nodes (LNs) has been roughly described as a random walk. Although it has been shown that dendritic cells (DCs) carrying cognate antigen in some circumstances attract T cells chemotactically, it is currently still unclear whether chemoattraction of T cells towards DCs helps or hampers scanning. Chemoattraction towards DCs could on the one hand help T cells to rapidly find DCs. On the other hand, it could be deleterious if DCs become shielded by a multitude of attracted yet non-specific T cells. Results from a recent simulation study suggested that the deleterious effect dominates. We re-addressed the question whether T cell chemoattraction towards DCs is expected to promote or hamper the detection of rare antigens using the Cellular Potts Model, a formalism that allows for dynamic, flexible cellular shapes and cell migration. Our simulations show that chemoattraction of T cells enhances the DC scanning efficiency, leading to an increased probability that rare antigen-specific T cells find DCs carrying cognate antigen. Desensitization of T cells after contact with a DC further improves the scanning efficiency, yielding an almost threefold enhancement compared to random migration. Moreover, the chemotaxis-driven migration still roughly appears as a random walk, hence fine-tuned analysis of cell tracks will be required to detect chemotaxis within microscopy data. PMID:23166480

  8. Chemotactic migration of T cells towards dendritic cells promotes the detection of rare antigens.

    PubMed

    Vroomans, Renske M A; Marée, Athanasius F M; de Boer, Rob J; Beltman, Joost B

    2012-01-01

    In many immunological processes chemoattraction is thought to play a role in guiding cells to their sites of action. However, based on in vivo two-photon microscopy experiments in the absence of cognate antigen, T cell migration in lymph nodes (LNs) has been roughly described as a random walk. Although it has been shown that dendritic cells (DCs) carrying cognate antigen in some circumstances attract T cells chemotactically, it is currently still unclear whether chemoattraction of T cells towards DCs helps or hampers scanning. Chemoattraction towards DCs could on the one hand help T cells to rapidly find DCs. On the other hand, it could be deleterious if DCs become shielded by a multitude of attracted yet non-specific T cells. Results from a recent simulation study suggested that the deleterious effect dominates. We re-addressed the question whether T cell chemoattraction towards DCs is expected to promote or hamper the detection of rare antigens using the Cellular Potts Model, a formalism that allows for dynamic, flexible cellular shapes and cell migration. Our simulations show that chemoattraction of T cells enhances the DC scanning efficiency, leading to an increased probability that rare antigen-specific T cells find DCs carrying cognate antigen. Desensitization of T cells after contact with a DC further improves the scanning efficiency, yielding an almost threefold enhancement compared to random migration. Moreover, the chemotaxis-driven migration still roughly appears as a random walk, hence fine-tuned analysis of cell tracks will be required to detect chemotaxis within microscopy data.

  9. 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.

  10. Chemotactic properties of Escherichia coli mutants having abnormal Ca2+ content.

    PubMed Central

    Tisa, L S; Adler, J

    1995-01-01

    The calA, calC, and calD mutants of Escherichia coli are known to be sensitive to Ca2+ (R. N. Brey and B. P. Rosen, J. Bacteriol. 139:824-834, 1979). In the absence of any added stimuli for chemotaxis, both the calC and the calD mutants swam with a tumbly bias. Both the calC and the calD mutants were defective in chemotaxis as measured by computer analysis, use of swarm plates, and capillary assays. The calA mutant was only slightly defective in motility and only slightly impaired in chemotaxis. Chemotactically wild-type cells had an intra-cellular free-Ca2+ level of about 105 nM. The intracellular free-Ca2+ levels of the mutants, as determined by use of the fluorescent Ca2+ indicator dye fura-2 or fluo-3, were about 90, about 1,130, and about 410 nM for calA, calC, and calD, respectively. Lowering the intracellular free-Ca2+ levels in wild-type cells and in the tumbly cal mutants by use of Ca2+ chelators promoted running (smooth swimming). Overexpression of CheZ (which causes dephosphorylation of CheY-phosphate) in the wild type and in the tumbly cal mutants decreased the level of tumbliness (which is caused by CheY-phosphate). The calA mutant was 4- to 10-fold more resistant than the wild type to the inhibitory effect of omega-conotoxin on chemotaxis. omega-Conotoxin had no effect on Ca2+ extrusion by wild-type E. coli; that result suggests that omega-conotoxin affects Ca2+ transport at the point of entry instead of exit. PMID:8522517

  11. Mytilus galloprovincialis myticin C: a chemotactic molecule with antiviral activity and immunoregulatory properties.

    PubMed

    Balseiro, Pablo; Falcó, Alberto; Romero, Alejandro; Dios, Sonia; Martínez-López, Alicia; Figueras, Antonio; Estepa, Amparo; Novoa, Beatriz

    2011-01-01

    Previous research has shown that an antimicrobial peptide (AMP) of the myticin class C (Myt C) is the most abundantly expressed gene in cDNA and suppressive subtractive hybridization (SSH) libraries after immune stimulation of mussel Mytilus galloprovincialis. However, to date, the expression pattern, the antimicrobial activities and the immunomodulatory properties of the Myt C peptide have not been determined. In contrast, it is known that Myt C mRNA presents an unusual and high level of polymorphism of unidentified biological significance. Therefore, to provide a better understanding of the features of this interesting molecule, we have investigated its function using four different cloned and expressed variants of Myt C cDNA and polyclonal anti-Myt C sera. The in vivo results suggest that this AMP, mainly present in hemocytes, could be acting as an immune system modulator molecule because its overexpression was able to alter the expression of mussel immune-related genes (as the antimicrobial peptides Myticin B and Mytilin B, the C1q domain-containing protein MgC1q, and lysozyme). Moreover, the in vitro results indicate that Myt C peptides have antimicrobial and chemotactic properties. Their recombinant expression in a fish cell line conferred protection against two different fish viruses (enveloped and non-enveloped). Cell extracts from Myt C expressing fish cells were also able to attract hemocytes. All together, these results suggest that Myt C should be considered not only as an AMP but also as the first chemokine/cytokine-like molecule identified in bivalves and one of the few examples in all of the invertebrates.

  12. Exercise-induced release of histamine and neutrophil chemotactic factor in atopic asthmatics.

    PubMed

    Lee, T H; Brown, M J; Nagy, L; Causon, R; Walport, M J; Kay, A B

    1982-08-01

    Concentrations of plasma histamine and serum neutrophil chemotactic factor (NCF) were measured in seven atopic asthmatics who developed exercise-induced asthma (EIA) after a treadmill task. The results were compared with those obtained after inhalation of specific antigen or methacholine. Plasma histamine concentrations were measured with a novel double-isotope radiometric assay, and NCF was identified by its elution in the void volume fractions of Sephadex G-200 and as a single peak of activity at approximately 0.20 molar NaCl after anion exchange chromatography on diethylaminoethyl-Sephacel (pH 7.8). After exercise or antigen challenge, the time courses of appearance of both mediators were virtually identical and accompanied the increase in airways obstruction. There was a statistically significant correlation between the concentrations of histamine or NCF and the magnitude of airflow obstruction after exercise and antigen challenge. This suggested that there may be a direct association between mediator release and EIA or antigen-induced bronchoconstriction. In contrast, there were no significant elevations in circulating histamine and NCF after inhalation of methacholine, at concentrations giving a fall in FEV1 comparable to that induced by exercise or antigen. The prior administration of cromolyn to three asthmatics inhibited both their EIA and the release of histamine and NCF. When four asthmatics were exercised for periods of 1, 3, and 6 min, the release of NCF and fall in peak expiratory flow rate were directly related to the duration of the exercise. The rise of NCF activity in subjects with EIA was fivefold greater than that observed in asthmatics who did not experience airways obstruction when subjected to the same exercise task. These results provide further evidence that mediators of hypersensitivity are released during EIA.

  13. Synergic production of neutrophil chemotactic activity by colonic epithelial cells and eosinophils.

    PubMed

    Dent, Gordon; Loweth, Sam C; Hasan, Anwar Matar; Leslie, Fiona M

    2014-10-01

    The presence of eosinophils in the lumen and mucosa of the intestine is characteristic of both ulcerative colitis (UC) and Crohn's disease (CD). There is evidence of eosinophil activation in the intestine during acute inflammatory episodes of these diseases; these episodes are also characterized by an influx of neutrophils, which have the potential to cause extensive tissue damage. We undertook a study to determine whether eosinophils in contact with colonic epithelial cells produce factors that may attract neutrophils in response to immunological stimulation. Neutrophil chemotactic activity (NCA) and concentrations of three neutrophil-attracting CXC chemokines - CXCL1 (Groα), CXCL5 (Ena78) and CXCL8 (IL8) - were measured in supernatants of T84 colonic epithelial cells and blood eosinophils or eosinophil-like myeloid leukaemia cells (AML14.3D10), alone or in combination. Cells were stimulated with serum-opsonized zymosan (OZ) particles. NCA (P<0.005) and CXCL5 levels (P<0.05) in the supernatants of OZ-stimulated epithelial/eosinophil co-cultures were significantly higher than in the supernatants of either cell type alone. Release of CXCL1 (P<0.05) and CXCL8 (P<0.01) from OZ-stimulated co-culture supernatants was significantly higher than from OZ-stimulated eosinophils but not higher than from OZ-stimulated epithelial cells. Eosinophils and colonic epithelial cells exhibit synergy in production of neutrophil chemoattractants in response to immunological stimulation. This may represent a mechanism for exaggerated recruitment of neutrophils to the intestine in response to acute infection in conditions that are characterized by the presence of eosinophils in the bowel.

  14. Cytokines secreted by macrophages isolated from tumor microenvironment of inflammatory breast cancer patients possess chemotactic properties.

    PubMed

    Mohamed, Mona M; El-Ghonaimy, Eslam A; Nouh, Mohamed A; Schneider, Robert J; Sloane, Bonnie F; El-Shinawi, Mohamed

    2014-01-01

    Although there is a growing literature describing the role of macrophages in breast cancer, the role of macrophages in inflammatory breast cancer (IBC) is unclear. The aim of present study was to isolate and characterize tumor associated macrophages of IBC and non-IBC patients and define their role in IBC. Tumor infiltrating monocytes/macrophages (CD14+ and CD68+) were measured by immunohistochemistry using specific monoclonal antibodies. Blood drained from axillary vein tributaries was collected during breast cancer surgery and the percentage of CD14+ in the total isolated leukocytes was assessed by flow cytometric analysis. CD14+ cells were separated from total leukocytes by immuno-magnetic beads technique and were cultured overnight. Media conditioned by CD14+ were collected and subjected to cytokine profiling using cytokine antibody array. Wound healing and invasion assays were used to test whether cytokines highly secreted by tumor drained macrophages induce motility and invasion of breast cancer cells. We found that macrophages highly infiltrate into carcinoma tissues of IBC patients. In addition blood collected from axillary tributaries of IBC patients is highly enriched with CD14+ cells as compared to blood collected from non-IBC patients. Cytokine profiling of CD14+ cells isolated from IBC patients revealed a significant increase in secretion of tumor necrosis factor-α; monocyte chemoattractant protein-1/CC-chemokine ligand 2; interleukin-8 and interleukin-10 as compared to CD14+ cells isolated from non-IBC patients. Tumor necrosis factor-α, interleukin-8 and interleukin-10 significantly increased motility and invasion of IBC cells in vitro. In conclusion, macrophages isolated from the tumor microenvironment of IBC patients secrete chemotactic cytokines that may augment dissemination and metastasis of IBC carcinoma cells.

  15. Generic modeling of chemotactic based self-wiring of neural networks.

    PubMed

    Segev, R; Ben-Jacob, E

    2000-03-01

    The proper functioning of the nervous system depends critically on the intricate network of synaptic connections that are generated during the system development. During the network formation, the growth cones migrate through the embryonic environment to their targets using chemical communication. A major obstacle in the elucidation of fundamental principles underlying this self-wiring is the complexity of the system being analyzed. Hence much effort is devoted to in vitro experiments of simpler (two-dimensional) 2D model systems. In these experiments neurons are placed on Poly-L-Lysine (PLL) surfaces, so it is easier to monitor their self-wiring. We developed a model to reproduce the salient features of the 2D systems, inspired by the study of the growth of bacterial colonies and the aggregation of amoebae. We represent the neurons (each composed of cell's soma, neurites and growth cones) by active elements that capture the generic features of the real neurons. The model also incorporates stationary units representing the cells' soma and communicating walkers representing the growth cones. The stationary units send neurites one at a time, and respond to chemical signaling. The walkers migrate in response to chemotaxis substances emitted by the soma and communicate with each other and with the soma by means of chemotactic "feedback". The interplay between the chemo-repulsive and chemo-attractive responses is determined by the dynamics of the walker's internal energy which is controlled by the soma. These features enable the neurons to perform the complex task of self-wiring. We present numerical experiments of the model to demonstrate its ability to form fine structures in simple networks of few neurons. Our results raise two fundamental issues: (1) one needs to develop characterization methods (beyond number of connections per neuron) to distinguish the various possible networks; (2) what are the relations between the network organization and its computational

  16. High Genetic Diversity and Fine-Scale Spatial Structure in the Marine Flagellate Oxyrrhis marina (Dinophyceae) Uncovered by Microsatellite Loci

    PubMed Central

    Lowe, Chris D.; Montagnes, David J. S.; Martin, Laura E.; Watts, Phillip C.

    2010-01-01

    Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites) has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1–6 and 7–23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (He) of 0.00–0.30 and 0.81–0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional FST values indicated weak to moderate population sub-division (0.01–0.12), but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms. PMID:21203414

  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.

  18. Gravitaxis in the flagellate Euglena gracilis--results from NiZeMi, clinostat and sounding rocket flights.

    PubMed

    Häder, D P

    1994-05-01

    Many motile microorganisms including flagellates such as the green Euglena gracilis move up and down within the water column and use a number of external clues for their orientation, the most important of which may be light and gravity. The cells use positive phototaxis and negative gravitaxis to move closer to the surface of the water column which for energetic reasons is vital for their survival. However, most phytoplankton organisms cannot tolerate the bright irradiance of unfiltered solar radiation at the surface which also bleaches the photosynthetic pigments, disables the photosynthetic apparatus and impairs phototaxis, gravitaxis and motility in Euglena. Thus, it is not surprising that at higher irradiances negative phototaxis operates antagonistically to the responses described above to guide the cells into deeper water where they are protected from excessive radiation. Phototaxis and gravitaxis are not independent from one another: in a vertically positioned cuvette negative gravitaxis can be "titrated" by light impinging from above and is compensated at about 30 W m-2. While the photoreceptor for phototaxis has been identified in Euglena gracilis biochemically and spectroscopically, the gravireceptor is not yet known. Young cultures of Euglena gracilis show a positive gravitaxis, the ecological signficance of which is not yet understood while older cultures show negative gravitaxis. One hypothesis concerning the nature of graviperception is based on a passive physical process such as an asymmetric distribution of the mass within the cell. However, the observation that short term UV irradiation decreases the precision of negative gravitaxis rather indicates the involvement of an active physiological gravireceptor. Furthermore, some heavy metal ions have been found to change the direction of movement from positive to negative gravitaxis in young cells.

  19. High genetic diversity and fine-scale spatial structure in the marine flagellate Oxyrrhis marina (Dinophyceae) uncovered by microsatellite loci.

    PubMed

    Lowe, Chris D; Montagnes, David J S; Martin, Laura E; Watts, Phillip C

    2010-12-23

    Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites) has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1-6 and 7-23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (H(e)) of 0.00-0.30 and 0.81-0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional F(ST) values indicated weak to moderate population sub-division (0.01-0.12), but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms.

  20. Enhanced production of the chemotactic cytokines interleukin-8 and monocyte chemoattractant protein-1 in human abdominal aortic aneurysms.

    PubMed Central

    Koch, A. E.; Kunkel, S. L.; Pearce, W. H.; Shah, M. R.; Parikh, D.; Evanoff, H. L.; Haines, G. K.; Burdick, M. D.; Strieter, R. M.

    1993-01-01

    Inflammatory leukocytes play a central role in the pathogenesis of human atherosclerotic disease, from early atherogenesis to the late stages of atherosclerosis, such as aneurysm formation. We have shown previously that human abdominal aortic aneurysms are characterized by the presence of numerous chronic inflammatory cells throughout the vessel wall (Am J Pathol 1990, 137: 1199-1213). The signals that attract lymphocytes and monocytes into the aortic wall in aneurysmal disease remain to be precisely defined. We have studied the production of the chemotactic cytokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) by aortic tissues obtained from 47 subjects. We compared the antigenic production of these cytokines by explants of: 1) human abdominal aneurysmal tissue, 2) occlusive (atherosclerotic) aortas, and 3) normal aortas. IL-8, which is chemotactic for neutrophils, lymphocytes, and endothelial cells was liberated in greater quantities by abdominal aortic aneurysms than by occlusive or normal aortas. Using immunohistochemistry, macrophages, and to a lesser degree endothelial cells, were found to be positive for the expression of antigenic IL-8. Similarly, MCP-1, a potent chemotactic cytokine for monocytes/macrophages, was released by explants from abdominal aortic aneurysms in greater quantities than by explants from occlusive or normal aortas. Using immunohistochemistry, the predominant MCP-1 antigen-positive cells were macrophages and to a lesser extent smooth muscle cells. Our results indicate that human abdominal aortic aneurysms produce IL-8 and MCP-1, both of which may serve to recruit additional inflammatory cells into the abdominal aortic wall, hence perpetuating the inflammatory reaction that may result in the pathology of vessel wall destruction and aortic aneurysm formation. Images Figure 2 Figure 3 Figure 4 Figure 5 PMID:8494046

  1. Elastohydrodynamics of flagellated microorganisms

    NASA Astrophysics Data System (ADS)

    Li, Gaojin; Ardekani, Arezoo

    2016-11-01

    The swimming motion of many microorganisms and cells are achieved by the waving deformation of their cilia and flagella. The typical structure of flagella and cilia contains nine doublets of parallel microtubules in a cylindrical arrangement surrounding one pair of microtubules in the center. The dynein molecular motors internally drive the sliding motion between the neighboring microtubules and cause the bending motion of the flagella and cilia and drive the microorganism swimming motion. In this work, we develop a numerical model for a microorganism swimming by an internally self-driven filament. Our numerical method captures the interaction between the elasticity of the flagellum and the surround fluid. The no-slip boundary conditions are satisfied by an iterative distributed Lagrangian multiplier method. We also investigate the effects of the non-Newtonian fluid rheology on the motion of an elastic flagellum near a wall.

  2. The Nuclear Hormone Receptor Peroxisome Proliferator-Activated Receptor β/δ Potentiates Cell Chemotactism, Polarization, and Migration▿ †

    PubMed Central

    Tan, Nguan Soon; Icre, Guillaume; Montagner, Alexandra; Heggeler, Béatrice Bordier-ten; Wahli, Walter; Michalik, Liliane

    2007-01-01

    After an injury, keratinocytes acquire the plasticity necessary for the reepithelialization of the wound. Here, we identify a novel pathway by which a nuclear hormone receptor, until now better known for its metabolic functions, potentiates cell migration. We show that peroxisome proliferator-activated receptor β/δ (PPARβ/δ) enhances two phosphatidylinositol 3-kinase-dependent pathways, namely, the Akt and the Rho-GTPase pathways. This PPARβ/δ activity amplifies the response of keratinocytes to a chemotactic signal, promotes integrin recycling and remodeling of the actin cytoskeleton, and thereby favors cell migration. Using three-dimensional wound reconstructions, we demonstrate that these defects have a strong impact on in vivo skin healing, since PPARβ/δ−/− mice show an unexpected and rare epithelialization phenotype. Our findings demonstrate that nuclear hormone receptors not only regulate intercellular communication at the organism level but also participate in cell responses to a chemotactic signal. The implications of our findings may be far-reaching, considering that the mechanisms described here are important in many physiological and pathological situations. PMID:17682064

  3. Enzymatic digestion of the milk protein beta-casein releases potent chemotactic peptide(s) for monocytes and macrophages.

    PubMed

    Kitazawa, Haruki; Yonezawa, Kumiko; Tohno, Masanori; Shimosato, Takeshi; Kawai, Yasushi; Saito, Tadao; Wang, Ji Ming

    2007-09-01

    Proteins in the milk release biologically active peptides upon enzymatic digestion. In the present study, we report the identification of novel monocyte/macrophage chemotactic peptides derived from enzymatically digested bovine beta-casein, a casein family member that is a major constituent of milk. Beta-casein fragments generated by actinase E showed potent chemotactic activity for human and mouse monocytes/macrophages, but not neutrophils, T lymphocytes or dendritic cells. The fragment-induced migration of human monocytes was inhibited by pertussis toxin and was not desensitized by a variety of known chemoattractants, suggesting that the digests activate a unique G protein-coupled receptor(s). The digests were further fractionated and purified to yield 3 small peptides. One peptide Q1 designated as "beta-casochemotide-1" with the amino acid sequence of YPVEP (f114-118 of beta-casein) induced high levels of macrophage chemotaxis. It also promoted calcium mobilization in macrophages, another indication of cell activation. Our study suggests that biologically active peptides released by actinase-digested milk beta-casein may promote innate host immune responses by inducing macrophage migration and activation.

  4. The effects of oral consumption of selenium nanoparticles on chemotactic and respiratory burst activities of neutrophils in comparison with sodium selenite in sheep.

    PubMed

    Kojouri, Gholam Ali; Sadeghian, Sirous; Mohebbi, Abdonnaser; Mokhber Dezfouli, Mohammad Reza

    2012-05-01

    The present study was designed to compare the effects of nano-selenium and of sodium selenite on the chemotactic and respiratory burst activities of neutrophils in sheep. Fifteen sheep were randomly divided into three groups. Groups 1 and 2 received selenium nanoparticles (1 mg/kg) or sodium selenite (1 mg/kg) orally, respectively, for ten consecutive days, and the third group was considered as the control. To determine the chemotactic and respiratory burst activities of the neutrophils, the leading front assay and the NBT test were used on heparinized blood samples that were collected at different intervals (days 0, 10th, 20th, and 30th). The results obtained showed that the chemotactic activities in groups 1 and 2 increased significantly on the 10th, 20th, and 30th day, compared to day 0, and on the 20th day in comparison with the 10th day, while in group 2, there was a significant decrease on the 30th day compared to the 20th day. The chemotactic activities in group 1 were significantly higher than in group 2 on the 10th day and in the control group on the 10th, 20th, and 30th day, but the chemotactic activities in group 2 were significantly higher than those in the control group only on the 20th day. On the 30th day into the experiment, the respiratory bursts in groups 1 and 2 were significantly stronger in comparison with those at day 0. Overall, nano-selenium increased the chemotactic and respiratory burst activities more significantly than sodium selenite, which is suggestive of a stronger stimulatory effect of the Se nanoparticles on intracellular activities.

  5. Generation of a complement-derived chemotactic factor for tumor cells in experimentally induced peritoneal exudates and its effect on the local metastasis of circulating tumor cells.

    PubMed Central

    Orr, F. W.; Mokashi, S.; Delikatny, J.

    1982-01-01

    A chemotactic factor for tumor cells was found in inflammatory exudate fluids induced by giving intraperitoneal injections of glycogen to Sprague-Dawley rats. The quantity of chemotactic activity and the period of time during which it could be detected correlated with the inflammatory reaction, measured by the cellular composition of the exudates and their content of protein and lysosomal enzymes. In gel filtration the chemotactic factor behaved mainly as a molecule having a molecular weight of approximately 6000 daltons. Its biologic activity was blocked by antiserums directed against C5 but not by antiserums against C3 or C4. In these two respects, the factor generated in vivo has the same properties as a previously described chemotactic factor that can be generated in vitro by proteolysis of purified C5 or C5a. Chemotactic activity was not detected in the glycogen-induced peritoneal exudates of rats depleted of serum complement by cobra venom factor. Intravenously injected Walker tumor cells arrested and formed metastases in the mesenteries of rats with peritonitis in greater numbers than in normal controls, animals depleted of complement during the experimental period, or animals given intraperitoneal injections of the vasopermeability agent, histamine. The growth of tumor cells in vitro was not promoted by peritoneal exudate fluids, nor was the number of metastases on vivo greater than in negative controls, in animals in which peritonitis was induced 24 hours after the intravenous injection of tumor cells. It is argued that chemotactic mechanisms can contribute to the formation of metastases at sites of tissue injury. PMID:7091299

  6. Cryptic chemotactic activity of fibronectin for human monocytes resides in the 120-kDa fibroblastic cell-binding fragment.

    PubMed

    Clark, R A; Wikner, N E; Doherty, D E; Norris, D A

    1988-08-25

    Monocytes and lymphocytes form a second wave of infiltrating blood leukocytes in areas of tissue injury. The mechanisms for monocyte accumulation at these sites are not completely understood. Recently, however, fragments from extracellular matrix proteins including collagen, elastin, and fibronectin have been shown to induce monocyte chemotaxis. In this report we demonstrate that chemotactic activity for human monocytes is expressed when a 120-kDa fragment containing the RGDS cell-binding peptide is released from intact fibronectin or from larger fibronectin fragments. Monocytes, either from mononuclear cell Ficoll-Hypaque preparations (10-20% monocytes, 89-90% lymphocytes) or from elutriation preparations (95% monocytes, 5% lymphocytes), but not lymphocytes, migrated toward 120-kDa fragment preparations (10(-7) M) in blind-end chambers when the cells were separated from the chemoattractant by a 5-micron pore polycarbonate filter either alone or overlying a 0.45-micron pore nitrocellulose filter. Neutrophils migrated toward zymosan-activated serum but not toward 10(-5)-10(-8) M concentrations of the 120-kDa fragment. Intact fibronectin had no chemotactic activity for human monocytes. Fibronectin was isolated from citrated human plasma by sequential gelatin-Sepharose affinity and DEAE ion-exchange chromatography in the presence of buffers containing 1 mM phenylmethylsulfonyl fluoride to prevent fragmentation. Controlled enzymatic digestion with thermolysin cleaved fibronectin into 30 kDa fibrin, 45 kDa collagen, and 150/160-kDa cell and heparin domains. Upon prolonged digestion, purified 150/160-kDa fragments were cleaved into 120-kDa cell and 30/40-kDa heparin-binding fragments. Even though the intact fibronectin molecule, the 150/160-kDa fragments, and the 120-kDa fragment, have cell binding activity for Chinese hamster ovary fibroblasts, only the 120-kDa fragment expressed chemotactic activity for human monocytes. Thus, the 120-kDa fibroblastic cell

  7. Monocyte chemotactic protein-1 attenuates and high-fat diet exacerbates bone loss in mice with pulmonary metastasis of Lewis lung carcinoma

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bone can be adversely affected by obesity and cancer-associated complications including wasting. The objective of this study was to determine whether a high-fat diet and a deficiency in monocyte chemotactic protein-1 (MCP-1) altered bone structural defects found in male C57BL/6 mice with Lewis lung...

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

    PubMed Central

    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. 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.

  11. Agent-Based Model of Human Alveoli Predicts Chemotactic Signaling by Epithelial Cells during Early Aspergillus fumigatus Infection

    PubMed Central

    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

  12. Role of Interleukin-17A on the Chemotactic Responses to CCL7 in a Murine Allergic Rhinitis Model

    PubMed Central

    Zhang, Yu-Lian; Han, Doo Hee; Kim, Dong-Young; Lee, Chul Hee; Rhee, Chae-Seo

    2017-01-01

    Background The proinflammatory cytokine interleukin (IL)-17A is associated with eosinophil infiltration into the nasal mucosa in a mouse model of ovalbumin-induced allergic rhinitis. Chemotaxis of eosinophils is mediated primarily through C-C chemokine receptor type 3 (CCR3). However, the mechanism underlying the IL-17A-mediated enhancement of eosinophil recruitment via chemoattractants/chemokines remains unknown. Objectives In this study, we assessed the contribution of IL-17A to eosinophil-related inflammation via the CCL7/CCR3 pathway in experimental allergic rhinitis. Methods IL-17A knockout (KO) and wild-type (WT) BALB/c mice were injected intraperitoneally and challenged intranasally with OVA to induce allergic rhinitis. Various parameters of the allergic response were evaluated, and mRNA and protein levels of CCL7 and CCR3 in nasal tissue and serum were compared between the two groups. The chemotactic response to CCL7 with or without IL-17A in bone marrow-derived eosinophils (bmEos) from BALB/c mice was measured. Results In the allergic rhinitis model, IL-17A deficiency significantly decreased nasal symptoms, serum IgE levels, and eosinophil recruitment to the nasal mucosa. CCL7 and CCR3 mRNA and protein levels were decreased in the nasal mucosa of IL-17A KO mice compared with the WT mice. BmEos showed a significantly increased chemotactic response to -low concentration of CCL7 in the presence of IL-17A compared with its absence. Conclusion The suppression of nasal inflammation due of IL-17A deficiency in allergic rhinitis is partly responsible for the regulation of CCL7 secretion and eosinophil infiltration, which may be regulated via the CCL7/CCR3 pathway. PMID:28046055

  13. 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

  14. Crystal and molecular structure of two geometrically restricted chemotactic tripeptides, analogues of formyl-methionine-leucine-phenylalanine.

    PubMed

    Michel, A G; Lajoie, G; Hassani, C A

    1990-12-01

    The crystal structures of HCO-Met-Leu-Phe-OC(CH3)3, (CH25H39N3O5S), fMLP-OtBu, and HCO-Met psi [CSNH]-Leu-Phe-OCH3, (C22H33N3O4S2), fMS LP-OMe, have been determined by single crystal X-ray diffraction, and their conformational properties investigated by molecular mechanics energy calculations. Crystals of fMLP-OtBu are monoclinic, space group P2(1), a = 12.027(4), b = 9.492(3), c = 12.660(4) A, beta = 101.99(3) degrees, Z = 2; those of fMS LP-OMe are orthorhombic, space group P2(1)2(1)2(1), a = 7.130(1), b = 12.097(2), c = 31.060(5) A, Z = 4. The first compounds fMLP-OtBu is the t-butyl ester of the tripeptide fMLP that represents one of the most potent compounds in inducing the lysozyme release from human neutrophils that reflects the chemotactic activity. From the crystal structure, it is shown that the orientation of the phenylalanine side chain is largely affected by the presence of the bulky group. fMSLP-OMe was shown to be inactive after thionation of the methionine residue in the original tripeptide. Nevertheless, the crystal structure does not reveal any influence of the presence of the thionated peptidic bond on the backbone conformation. The X-ray results have been used to generate parameters for empirical energy calculations. Subsequently, a strategy based on random generation of conformations followed by energy-minimization was applied to investigate the conformational space of thiopeptides, in comparison with normal peptides. From molecular free energy calculations, it is shown that the main influence of the introduction of a thioamide bond on the molecular structure is to prevent the existence of C7(eq) conformations involving the thiomethionine residue. Consequently, a larger number of conformers are found to form intramolecular hydrogen bonds involving the formyl group, reducing its availability to interact with the receptor. For the first time, the theoretical prediction of the existence of C7eq conformations for fMLP is made. The resulting

  15. 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

  16. Using optical tweezers to examine the chemotactic force to a single inflammatory cell--eosinophil stimulated by chemoattractants prepared from Toxocara Canis larvae

    NASA Astrophysics Data System (ADS)

    Shih, Po-Chen; Su, Yi-Jr; Chen, Ke-Min; Jen, Lin-Ni; Liu, Cheng-tzu; Hsu, Long

    2005-08-01

    Granulocytes are a group of white blood cells belonging to the innate immune system in human and in murine in which eosinophils play an important role in worm infection-induced inflammation. The migration of these cells is well characterized and has been separated into four steps: rolling, adhesion, transendothelial migration, and chemotaxis, however, the physical characteristics of the chemotactic force to eosinophils from worm component remain largely unknown. Note that optical tweezers are featured in the manipulation of a single cell and the measurement of biological forces. Therefore, we propose to use optical tweezers to examine the chemotactic force to a eosinophil from a T. canis lavae preparation in terms of distance during the migration of eosinophil.

  17. Renal leukocyte chemotactic factor 2 (LECT2) amyloidosis in First Nations people in Northern British Columbia, Canada: a report of 4 cases.

    PubMed

    Hutton, Holly L; DeMarco, Mari L; Magil, Alex B; Taylor, Paul

    2014-11-01

    Leukocyte chemotactic factor 2 (LECT2) amyloidosis is a recently identified type of amyloidosis that may represent an underdiagnosed cause of chronic kidney disease. LECT2 amyloidosis typically is reported as being renal limited and, in the United States, more prevalent in Hispanic patients. We add to the epidemiologic data of this condition by describing 4 First Nations people from Northern British Columbia, Canada, who presented with slowly progressive chronic kidney disease that was found to be due to LECT2 amyloidosis.

  18. A “Trimer of Dimers”—Based Model for the Chemotactic Signal Transduction Network in Bacterial Chemotaxis

    PubMed Central

    Xin, Xiangrong

    2013-01-01

    The network that controls chemotaxis in Escherichia coli is one of the most completely characterized signal transduction systems to date. Receptor clustering accounts for characteristics such as high sensitivity, precise adaptation over a wide dynamic range of ligand concentrations, and robustness to variations in the amounts of intracellular proteins. To gain insights into the structure-function relationship of receptor clusters and understand the mechanism behind the high-performance signaling, we develop and analyze a model for a single trimer of dimers. This new model extends an earlier model (Spiro et al. in Proc. Natl. Acad. Sci. 94:7263–7268, 1997) to incorporate the recent experimental findings that the core structure of receptor clusters is the trimer of receptor dimers. We show that the model can reproduce most of the experimentally-observed behaviors, including excitation, adaptation, high sensitivity, and robustness to parameter variations. In addition, the model makes a number of new predictions as to how the adaptation time varies with the expression level of various proteins involved in signal transduction. Our results provide a more mechanistically-based description of the structure-function relationship for the signaling system, and show the key role of the interaction among dimer members of the trimer in the chemotactic response of cells. PMID:22864951

  19. 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

  20. 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.

  1. Resveratrol inhibits foam cell formation via NADPH oxidase 1-mediated reactive oxygen species and monocyte chemotactic protein-1

    PubMed Central

    Park, Dae-Weon; Baek, Kheewoong; Kim, Jae-Ryong; Lee, Jae-Jin; Ryu, Sang-Ho; Chin, Byung-Rho

    2009-01-01

    Resveratrol is a polyphenolic compound in red wine that has anti-oxidant and cardioprotective effects in animal models. Reactive oxygen species (ROS) and monocyte chemotactic protein-1 (MCP-1) play key roles in foam cell formation and atherosclerosis. We studied LPS-mediated foam cell formation and the effect of resveratrol. Resveratrol pretreatment strongly suppressed LPS-induced foam cell formation. To determine if resveratrol affected the expression of genes that control ROS generation in macrophages, NADPH oxidase 1 (Nox1) was measured. Resveratrol treatment of macrophages inhibited LPS-induced Nox1 expression as well as ROS generation, and also suppressed LPS-induced MCP-1 mRNA and protein expression. We investigated the upstream targets of Nox1 and MCP-1 expression and found that Akt-forkhead transcription factors of the O class (FoxO3a) is an important signaling pathway that regulates both genes. These inhibitory effects of resveratrol on Nox1 expression and MCP-1 production may target to the Akt and FoxO3a signaling pathways. PMID:19293636

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

    PubMed

    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

    2015-03-10

    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.

  3. A new SPH scheme to model transport of chemotactic bacteria in porous media at the continuum scale

    NASA Astrophysics Data System (ADS)

    Avesani, Diego; Bellin, Alberto; Dumbser, Michael; Chiogna, Gabriele

    2015-04-01

    As recently shown chemotaxis, i.e. the movement of microorganisms toward or away from the concentration gradient of a chemical species, could have a fundamental role in the transport of bacteria through saturated porous media. Chemotactic bacteria could enhance bioremediation by directing their own motions to residual contaminants in less conductive zones of aquifers. The aim of the present work is to develop a proper numerical scheme to define and to quantify the magnitude and the role of chemotaxis in the complex groundwater system framework. We present a new class of meshless Lagrangian particle methods based on the Smooth Particle Hydrodinamics (SPH) formulation of Vila & Ben Moussa, combined with a new Weighted Essentially Non-Oscillatory (WENO) reconstruction technique on moving point clouds in multiple space dimensions. The purpose of this new scheme is to fully exploit the advantages of SPH among traditional meshbased and meshfree schemes and to overcome its problems for modeling chemotaxis in porous media. We test the new scheme against analytical reference solutions and we show, under the assumption of complete mixing at the Darcy scale, that chemotaxis may significantly affect the quantification of field-scale bacterial distribution, therefore influencing reactive mixing and degradation of contaminants.

  4. 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.

  5. Bacterial swimming, swarming and chemotactic response to heavy metal presence: which could be the influence on wastewater biotreatment efficiency?

    PubMed

    Barrionuevo, Matías R; Vullo, Diana L

    2012-09-01

    Fixed-bed reactors are usually designed for wastewater biotreatments, where the biofilm establishment and maintenance play the most important roles. Biofilm development strictly relies on different types of bacterial motility: swimming, swarming, and chemotaxis, which can be altered by the microenvironment conditions. The aim of this work is to do an integrated study on the effects of Cu(II), Cd(II), Zn(II) and Cr(VI) on swimming, swarming and chemotaxis of Pseudomonas veronii 2E, Delftia acidovorans AR and Ralstonia taiwanensis M2 to improve biofilm development and maintenance for metal loaded wastewater biotreatment in fixed-bed bioreactors. Swimming, swarming and chemotactic response evaluation experiments were carried out at different metal concentrations. P. veronii 2E motility was not affected by metal presence, being this strain optimal for fixed-bed reactors. D. acidovorans AR swarming was inhibited by Cd and Zn. Although R. taiwanensis M2 showed high resistance to Cu, Cd, Cr and Zn, motility was definitively altered, so further studies on R. taiwanensis M2 resistance mechanisms would be particularly interesting.

  6. Vascular Endothelial Growth Factor (VEGF) Promotes Assembly of the p130Cas Interactome to Drive Endothelial Chemotactic Signaling and Angiogenesis*

    PubMed Central

    Evans, Ian M.; Kennedy, Susan A.; Paliashvili, Ketevan; Santra, Tapesh; Yamaji, Maiko; Lovering, Ruth C.; Britton, Gary; Frankel, Paul; Kolch, Walter; Zachary, Ian C.

    2017-01-01

    p130Cas is a polyvalent adapter protein essential for cardiovascular development, and with a key role in cell movement. In order to identify the pathways by which p130Cas exerts its biological functions in endothelial cells we mapped the p130Cas interactome and its dynamic changes in response to VEGF using high-resolution mass spectrometry and reconstruction of protein interaction (PPI) networks with the aid of multiple PPI databases. VEGF enriched the p130Cas interactome in proteins involved in actin cytoskeletal dynamics and cell movement, including actin-binding proteins, small GTPases and regulators or binders of GTPases. Detailed studies showed that p130Cas association of the GTPase-binding scaffold protein, IQGAP1, plays a key role in VEGF chemotactic signaling, endothelial polarization, VEGF-induced cell migration, and endothelial tube formation. These findings indicate a cardinal role for assembly of the p130Cas interactome in mediating the cell migratory response to VEGF in angiogenesis, and provide a basis for further studies of p130Cas in cell movement. PMID:28007913

  7. Boar seminal plasma or hen's egg yolk decrease the in-vitro chemotactic and phagocytotic activities of neutrophils when co-incubated with boar or bull sperm.

    PubMed

    Li, J-C; Yamaguchi, S; Funahashi, H

    2012-01-01

    The objective was to determine the effects of boar seminal plasma and hen's egg yolk on chemotaxis and phagocytosis of porcine and bovine polymorphonuclear neutrophils (PMNs) in vitro. Chemotactic activity of PMNs was determined following culture for 90 min in a blind well chamber. Phagocytosis was assayed after co-culture of PMNs with sperm for 60 min. In the presence of ≥5% boar seminal plasma, chemotactic activity of PMNs was reduced (P<0.05) in both pigs (from 1126.1 to 934.2-1009.1 cells/mm2) and in cows (from 1067.1 to 768.9-800.0 cells/mm2). Furthermore, ≥5% boar seminal plasma reduced (P<0.05) leukocyte phagocytosis in pigs (26.2-32.1%) and cows (27.2-30.0%) compared to controls (41.7 and 42.1%, respectively). Although 20% hen's egg yolk increased (P<0.05) chemotactic activity of PMNs in pigs (from 790.4 to 1006.1 cells/mm2) and cows (from 789.9 to 953.5 cells/mm2), egg yolk increased (P<0.05) phagocytotic activity of porcine PMNs (from 24.3 to 33.8%), but not the activity of bovine PMNs (15.1 vs 15.8% in controls). Boar seminal plasma and caffeine reduced (P<0.05) the egg yolk-induced increase in chemotaxis in both species (from 988.6 to 795.2 or 813.2 cells/mm2 in pigs and from 953.5 to 779.4 or 833.8 cells/mm2 in cows), and phagocytotic activities of PMN (from 33.8% to 15.2 or 13.3%) only in pigs (but not in cows; 11.2-15.1%). In conclusion, hen's egg yolk increased chemotactic activity of PMNs in both pigs and cows, whereas egg yolk increased only phagocytosis of PMNs in pigs, but not in cows. Even in the presence of egg yolk, boar seminal plasma and caffeine significantly reduced chemotactic activity of PMNs in pigs and cows, and phagocytotic activity of porcine PMNs.

  8. Species diversity and flagellate infections in the sand fly fauna near Porto Grande, State of Amapá, Brazil (Diptera: Psychodidae. Kinetoplastida: Trypanosomatidae).

    PubMed

    Freitas, Rui A; Naiff, Roberto D; Barrett, Toby V

    2002-01-01

    Forty-six species of Lutzomyia and one species of Brumptomyia were identified among 20,008 sand flies collected in central Amapá. L. squamiventris maripaensis, L. infraspinosa, L. umbratilis, and L. ubiquitalis accounted for 66% of the specimens caught in light traps, and L. umbratilis was the commonest of the 16 species found on tree bases. Seven species of Lutzomyia including L. umbratilis were collected in a plantation of Caribbean pine. Sixty out of 511 female sand flies dissected were positive for flagellates. Among the sand flies from which Leishmania was isolated, promastigotes were observed in the salivary glands and foregut of 13 out of 21 females scored as having very heavy infections in the remainder of the gut, reinforcing the idea that salivary gland invasion may be part of the normal life cycle of Leishmania in nature. Salivary gland infections were detected in specimens of L. umbratilis, L. whitmani and L. spathotrichia. Parasites isolated from L. umbratilis, L. whitmani and also from one specimen of L. dendrophyla containing the remains of a bloodmeal, were compatible with Le. guyanensis by morphology and behaviour in hamsters.

  9. 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.

  10. Sputum chemotactic activity in chronic obstructive pulmonary disease: effect of α1–antitrypsin deficiency and the role of leukotriene B4 and interleukin 8

    PubMed Central

    Woolhouse, I; Bayley, D; Stockley, R

    2002-01-01

    Background: Neutrophil recruitment to the airway is thought to be an important component of continuing inflammation and progression of chronic obstructive pulmonary disease (COPD), particularly in the presence of severe α1–antitrypsin (α1–AT) deficiency. However, the chemoattractant nature of secretions from these patients has yet to be clarified. Methods: The chemotactic activity of spontaneous sputum from patients with stable COPD, with (n=11) and without (n=11) α1–AT deficiency (PiZ), was assessed using the under-agarose assay. The contribution of leukotriene B4 (LTB4) and interleukin 8 (IL-8) to the chemotactic activity was examined using an LTB4 receptor antagonist (BIIL 315 ZW) and an IL-8 monoclonal antibody, respectively. Results: Sputum neutrophil chemotactic activity (expressed as % n-formylmethionyl leucylphenylalanine (fMLP) control) was significantly higher in patients with α1–AT deficiency (mean (SE) 63.4 (8.9)% v 36.7 (5.5)%; mean difference 26.7% (95% CI 4.9 to 48.4), p<0.05). The mean (SE) contribution of both LTB4 and IL-8 (expressed as % fMLP control) was also significantly higher in α1–AT deficient patients than in patients with COPD with normal levels of α1–AT (LTB4: 31.9 (6.3)% v 18.0 (3.7)%; mean difference 13.9% (95% CI –1.4 to 29.1), p<0.05; IL-8: 24.1 (5.2)% v 8.1 (1.2)%; mean difference 15.9% (95% CI 4.7 to 27.2), p<0.05). When all the subjects were considered together the mean (SE) contribution of LTB4 (expressed as % total chemotactic activity) was significantly higher than IL-8 (46.8 (3.5)% v 30.8 (4.6)%; mean difference 16.0% (95% CI 2.9 to 29.2), p<0.05). This difference was not significantly influenced by α1–AT phenotype (p=0.606). Conclusions: These results suggest that the bronchial secretions of COPD patients with α1–AT deficiency have increased neutrophil chemotactic activity. This relates to the increased levels of IL-8 and, in particular LTB4, which accounted most of the sputum chemotactic activity in

  11. Abnormal mobility of neonatal polymorphonuclear leukocytes. Relationship to impaired redistribution of surface adhesion sites by chemotactic factor or colchicine.

    PubMed Central

    Anderson, D C; Hughes, B J; Smith, C W

    1981-01-01

    To determine the mechanism(s) of diminished, stimulated, and directed migration of neonatal (N) polymorphonuclear leukocytes (PMN), chemotactic factor (CF) sensory and PMN effector functions were studied in healthy N and adult or maternal controls (C). N PMN demonstrated high affinity binding for N-formyl-methionyl-leucyl-[3H]phenylalanine (fMLP), which was saturable between 40 and 100 nM as observed with C PMN. The kinetics of binding and the characteristics of dissociation of binding by N PMN were equivalent to control PMN. Both "threshold" and "peak" concentrations (1 and 10 nM, respectively) of fMLP effected comparable PMN chemiluminescence among neonates and controls. An equivalent threshold concentration (0.05 nM) of fMLP effected N and C PMN shape change in suspension, and a maximally effective concentration (5 nM) induced comparable bipolar configuration, although uropod formation was only 38 +/- 8% of N PMN, compared with 73 +/- 11% of C PMN (P less than 0.01). Striking abnormalities of N PMN adherence were identified: mean +/- SD base-line (unstimulated) N adherence values (39 +/- 8%) were equal to C (38 +/- 9%), but diminished increments in response to single CF stimuli were noted among N (fMLP: 42 +/- 7% (N), 70 +/- 11% (C); C5a: 41 +/- 6% (N), 68 +/- 6% (C); BCF: 41 +/- 6% (N), 63 +/- 9% (C), P less than 0.01 for each CF). On sequential exposure to increasing concentrations of CF N PMN failed to demonstrate expected decreased adherence values; sequential stimuli with fMLP (0.1 nM, 10 nM) or C5a (8 microgram protein/ml, 32 microgram protein/ml) effected mean +/- 1 SD values of 51 +/- 9% (N), 30 +/- 9% (C), and 34 +/- 10 (N), 48 +/- 14% (C), respectively. As demonstrated with a latex bead-binding technique, N PMN failed to redistribute adhesion sites to the cell's tail under the same experimental conditions; in 21 N samples studied, restricted unipolar binding occurred in 33 +/- 8% (fMLP) or 37 +/- 7% (C5a) of PMN in contrast to C values of 70% (f

  12. Osteopontin Undergoes Polymerization in Vivo and Gains Chemotactic Activity for Neutrophils Mediated by Integrin α9β1*

    PubMed Central

    Nishimichi, Norihisa; Hayashita-Kinoh, Hiromi; Chen, Chun; Matsuda, Haruo; Sheppard, Dean; Yokosaki, Yasuyuki

    2011-01-01

    Osteopontin (OPN) is an integrin-binding inflammatory cytokine that undergoes polymerization catalyzed by transglutaminase 2. We have previously reported that polymeric OPN (polyOPN), but not unpolymerized OPN (OPN*), attracts neutrophils in vitro by presenting an acquired binding site for integrin α9β1. Among many in vitro substrates for transglutaminase 2, only a few have evidence for in vivo polymerization and concomitant function. Although polyOPN has been identified in bone and aorta, the in vivo functional significance of polyOPN is unknown. To determine whether OPN polymerization contributes to neutrophil recruitment in vivo, we injected OPN* into the peritoneal space of mice. Polymeric OPN was detected by immunoblotting in the peritoneal wash of mice injected with OPN*, and both intraperitoneal and plasma OPN* levels were higher in mice injected with a polymerization-incompetent mutant, confirming that OPN* polymerizes in vivo. OPN* injection induced neutrophil accumulation, which was significantly less following injection of a mutant OPN that was incapable of polymerization. The importance of in vivo polymerization was further confirmed with cystamine, a transglutaminase inhibitor, which blocked the polymerization and attenuated OPN*-mediated neutrophil recruitment. The thrombin-cleaved N-terminal fragment of OPN, another ligand for α9β1, was not responsible for neutrophil accumulation because a thrombin cleavage-incompetent mutant recruited similar numbers of neutrophils as wild type OPN*. Neutrophil accumulation in response to both wild type and thrombin cleavage-incompetent OPN* was reduced in mice lacking the integrin α9 subunit in leukocytes, indicating that α9β1 is required for polymerization-induced recruitment. We have illustrated a physiological role of molecular polymerization by demonstrating acquired chemotactic properties for OPN. PMID:21321126

  13. Resveratrol Inhibits Expression and Binding Activity of the Monocyte Chemotactic Protein-1 Receptor, CCR2, on THP-1 Monocytes

    PubMed Central

    Cullen, John P.; Morrow, David; Jin, Ying; von Offenberg Sweeney, Nicholas; Sitzmann, James V.; Cahill, Paul A.; Redmond, Eileen M.

    2007-01-01

    Monocyte chemotactic protein-1 and its receptor, CCR2, play a key role in atherosclerosis. We determined the effect of the polyphenol, resveratrol, on CCR2 and the mechanisms involved. Resveratrol treatment inhibited 125I-MCP-1 binding to THP-1 cells; 31%, 56%, 84% decrease for 10, 50 and 100 µM resveratrol, in the absence of any effect on receptor affinity. The inhibitory effect of resveratrol on 125I-MCP-1 binding to THP-1 cells and on CCR2 protein expression determined by FACS analysis was attenuated by treatment with L-NAME (NOS inhibitor), PD98059 (MAPK inhibitor) and LY294002 (PI3K inhibitor), whereas neither X/XO (reactive oxygen species generator) nor ICI182780 (estrogen receptor antagonist) had any effect. Concomitant with a decrease in CCR2 protein expression, resveratrol inhibited THP-1 CCR2 mRNA levels, in the absence of any effect on its stability; 26% and 45% inhibition at 10 and 50 µM resveratrol, respectively. This effect was not altered by co-treatment with L-NAME, PD98059 or ICI182780, but was potentiated by LY294002 and X/XO. Conclusions: Resveratrol inhibits monocyte CCR2 binding activity in an NO-, MAPK- and PI3K-dependent manner, whereas it inhibits CCR2 mRNA in an NO- and MAPK-independent, PI3K-dependent manner. These inhibitory effects of resveratrol on chemokine receptor binding and expression may contribute, in part, to its cardiovascular protective activity in vivo. PMID:17499741

  14. Cathepsin K cleavage of SDF-1α inhibits its chemotactic activity towards glioblastoma stem-like cells.

    PubMed

    Hira, Vashendriya V V; Verbovšek, Urška; Breznik, Barbara; Srdič, Matic; Novinec, Marko; Kakar, Hala; Wormer, Jill; der Swaan, Britt Van; Lenarčič, Brigita; Juliano, Luiz; Mehta, Shwetal; Van Noorden, Cornelis J F; Lah, Tamara T

    2017-03-01

    Glioblastoma (GBM) is the most aggressive primary brain tumor with poor patient survival that is at least partly caused by malignant and therapy-resistant glioma stem-like cells (GSLCs) that are protected in GSLC niches. Previously, we have shown that the chemo-attractant stromal-derived factor-1α (SDF-1α), its C-X-C receptor type 4 (CXCR4) and the cysteine protease cathepsin K (CatK) are localized in GSLC niches in glioblastoma. Here, we investigated whether SDF-1α is a niche factor that through its interactions with CXCR4 and/or its second receptor CXCR7 on GSLCs facilitates their homing to niches. Furthermore, we aimed to prove that SDF-1α cleavage by CatK inactivates SDF-1α and inhibits the invasion of GSLCs. We performed mass spectrometric analysis of cleavage products of SDF-1α after proteolysis by CatK. We demonstrated that CatK cleaves SDF-1α at 3 sites in the N-terminus, which is the region of SDF-1α that binds to its receptors. Confocal imaging of human GBM tissue sections confirmed co-localization of SDF-1α and CatK in GSLC niches. In accordance, 2D and 3D invasion experiments using CXCR4/CXCR7-expressing GSLCs and GBM cells showed that SDF-1α had chemotactic activity whereas CatK cleavage products of SDF-1α did not. Besides, CXCR4 inhibitor plerixafor inhibited invasion of CXCR4/CXCR7-expressing GSLCs. In conclusion, CatK can cleave and inactivate SDF-1α. This implies that CatK activity facilitates migration of GSLCs out of niches. We propose that activation of CatK may be a promising strategy to prevent homing of GSLCs in niches and thus render these cells sensitive to chemotherapy and radiation.

  15. Differential neutrophil chemotactic response towards IL-8 and bacterial N-formyl peptides in term newborn infants

    PubMed Central

    Stålhammar, Maria E.; Douhan Håkansson, Lena; Jonzon, Anders; Sindelar, Richard

    2017-01-01

    Background A prerequisite for an effective innate immunity is the migrative ability of neutrophils to respond to inflammatory and infectious agents such as the intermediate interleukin (IL)-8 and the end-target formyl-methionyl-leucyl-phenylalanine (fMLP) chemoattractants. The aim was to study the chemotactic capacity of neutrophils from newborn infants and adults in response to IL-8 and the bacterial peptide fMLP. Methods In the under-agarose cell migration assay, isolated leukocytes from healthy adults and from cord blood of healthy term newborn infants were studied with dose responses towards IL-8 and fMLP. The same number of leukocytes (1 × 105 cells), with the same distribution of neutrophils and monocytes, were analyzed in neonates and adults. Chemotaxis was distinguished from randomly migrating neutrophils, and the neutrophil pattern of migration, i.e. the migration distance and the number of migrating neutrophils per distance, was evaluated. Results In comparison to adults, fewer neutrophils from newborn infants migrated towards IL-8 and for a shorter distance (P < .01, respectively). The number of neutrophils migrating to different gradients of fMLP, the distance they migrated, and the correlation between the number and the distance were the same for neonates and adults. Random migration did not differ in any instance. Conclusion Chemotaxis of neutrophils from newborn infants was as co-ordinated as neutrophils from adults in response to fMLP, whereas the response to IL-8 was reduced. The differential response of neutrophils from neonates to intermediate and end-target chemoattractants could indicate a reduced infectious response. PMID:27690722

  16. Instabilities in the Swimming of Bacteria

    NASA Astrophysics Data System (ADS)

    Riley, Emily; Lauga, Eric

    2016-11-01

    Peritrichously flagellated bacteria, such as E. coli and B. subtillis, have flagella randomly distributed over their body. These flagella rotate to generate a pushing force that causes the cell to swim body first. For changes in direction these flagella return to their randomly distributed state where the flagella point in many different directions. The main observed state of swimming peritrichously flagellated bacteria however is one where all their flagella gathered or bundled at one end of the body. In this work we address this problem from the point of view of fluid-structure interactions and show theoretically and numerically how the conformation of flagella depends on the mechanics of the cell.

  17. The alternative sigma factor sigma28 of Legionella pneumophila restores flagellation and motility to an Escherichia coli fliA mutant.

    PubMed Central

    Heuner, K; Hacker, J; Brand, B C

    1997-01-01

    Gene expression in Legionella pneumophila, the etiological agent of Legionnaires' disease, can be controlled by alternative forms of RNA polymerase programmed by distinct sigma factors. To understand the regulation of L. pneumophila flagellin expression, we cloned the sigma factor (FliA) of RNA polymerase responsible for the transcription of the flagellin gene, flaA. FliA is a member of the sigma28 class of alternative sigma factors identified in several bacterial genera. The gene fliA has been isolated from an expression library of L. pneumophila isolate Corby in Escherichia coli K-12. This library was transformed into a fliA mutant of E. coli K-12 containing a plasmid carrying the L. pneumophila-specific flaA promoter fused to the reporter gene luxAB. Screening the obtained transformants for luciferase activity, we isolated the major part of the fliA gene on a 1.64-kb fragment. This fragment was sequenced and used for reverse PCR in order to recover the complete fliA gene. The resulting 1.03-kb fragment was shown to contain the entire fliA gene. L. pneumophila FliA has 55 and 43% amino acid identity with the homologous sequences of Pseudomonas aeruginosa and E. coli. Furthermore, the L. pneumophila fliA gene was able to restore the flagellation and the motility defect of an E. coli fliA mutant. This result suggests that the L. pneumophila sigma28 protein can bind to the E. coli core RNA polymerase to direct transcription initiation from the flaA-specific promoter. PMID:8981975

  18. 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.

  19. Mitochondrial group II introns in the raphidophycean flagellate Chattonella spp. suggest a diatom-to-Chattonella lateral group II intron transfer.

    PubMed

    Kamikawa, Ryoma; Masuda, Isao; Demura, Mikihide; Oyama, Kenichi; Yoshimatsu, Sadaaki; Kawachi, Masanobu; Sako, Yoshihiko

    2009-08-01

    In the cytochrome c oxidase subunit I (cox1) gene of four raphidophycean flagellates Chattonella antiqua, C. marina, C. ovata, and C. minima we found two group II introns described here as Chattonella cox1-i1 and Chattonella cox1-i2 encoding an open reading frame (ORF) comprised of three domains: reverse transcriptase (RT), RNA maturase (Ma) and zinc finger (H-N-H) endonuclease domains. The secondary structures show both Chattonella cox1-i1 and Chattonella cox1-i2 belong to group IIA1, albeit the former possesses a group IIB-like secondary structural character in the epsilon' region of arm I. Our phylogenetic analysis inferred from RT domain sequences of the intronic ORF, comparison of the insertion sites, and the secondary structures of the introns suggests that Chattonella cox1-i1 likely shares an evolutionary origin with the group II introns inserted in cox1 genes of five phylogenetically diverged eukaryotes. In contrast, Chattonella cox1-i2 was suggested to bear a close evolutionary affinity to the group II introns found in diatom cox1 genes. The RT domain-based phylogeny shows a tree topology in which Chattonella cox1-i2 is nested in the diatom sequences suggesting that a diatom-to-Chattonella intron transfer has taken place. Finally, we found no intron in cox1 genes from deeper-branching raphidophyceans. Based on parsimonious discussion, Chattonella cox1-i1 and Chattonella cox1-i2 have invaded into the cox1 gene of an ancestral Chattonella cell after diverging from C. subsalsa.

  20. CD147 and CD98 complex-mediated homotypic aggregation attenuates the CypA-induced chemotactic effect on Jurkat T cells.

    PubMed

    Guo, Na; Zhang, Kui; Lv, Minghua; Miao, Jinlin; Chen, Zhinan; Zhu, Ping

    2015-02-01

    Homotypic cell aggregation plays important roles in physiological and pathological processes, including embryogenesis, immune responses, angiogenesis, tumor cell invasion and metastasis. CD147 has been implicated in most of these phenomena, and it was identified as a T cell activation-associated antigen due to its obvious up-regulation in activated T cells. However, the explicit function and mechanism of CD147 in T cells have not been fully elucidated. In this study, large and compact aggregates were observed in Jurkat T cells after treatment with the specific CD147 monoclonal antibody HAb18 or after the expression of CD147 was silenced by RNA interference, which indicated an inhibitory effect of CD147 in T cell homotypic aggregation. Knocking down CD147 expression resulted in a significant decrease in CD98, along with prominent cell aggregation, similar to that treated by CD98 and CD147 monoclonal antibodies. Furthermore, decreased cell chemotactic activity was observed following CD147- and CD98-mediated cell aggregation, and increased aggregation was correlated with a decrease in the chemotactic ability of the Jurkat T cells, suggesting that CD147- and CD98-mediated homotypic cell aggregation plays a negative role in T cell chemotaxis. Our data also showed that p-ERK, p-ZAP70, p-CD3ζ and p-LCK were significantly decreased in the CD147- and CD98-knocked down Jurkat T cells, which suggested that decreased CD147- and/or CD98-induced homotypic T cell aggregation and aggregation-inhibited chemotaxis might be associated with these signaling pathways. A role for CD147 in cell aggregation and chemotaxis was further indicated in primary CD4(+) T cells. Similarly, low expression of CD147 in primary T cells induced prominent cell aggregation and this aggregation attenuated primary T cell chemotactic ability in response to CypA. Our results have demonstrated the correlation between homotypic cell aggregation and the chemotactic response of T cells to CypA, and these data

  1. 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.

  2. The carboxyl terminus of the chemokine receptor CCR3 contains distinct domains which regulate chemotactic signaling and receptor down-regulation in a ligand-dependent manner.

    PubMed

    Sabroe, Ian; Jorritsma, Annelies; Stubbs, Victoria E L; Xanthou, Georgina; Jopling, Louise A; Ponath, Paul D; Williams, Timothy J; Murphy, Philip M; Pease, James E

    2005-04-01

    The chemokine receptor CCR3 regulates the chemotaxis of leukocytes implicated in allergic disease, such as eosinophils. Incubation of eosinophils with CCL11, CCL13 or CCL5 resulted in a rapid decrease of cell-surface CCR3 which was replicated using CCR3 transfectants. Progressive truncation of the CCR3 C terminus by 15 amino acids produced three constructs, Delta340, Delta325 and Delta310. Delta340 and Delta325 were able to bind CCL11 with affinities similar to wild-type CCR3. Delta340 transfectants exhibited enhanced migration and reduced receptor down-regulation in response to CCL11 and CCL13. Delta325 transfectants displayed chemotactic responses to CCL11 and CCL13 similar to wild-type CCR3, and had impaired down-regulation when stimulated with CCL13 but not CCL11. In contrast, neither the Delta325 nor Delta340 truncation affected chemotaxis or receptor down-regulation induced by CCL5. Delta310 transfectants bound CCL11 poorly and were biologically inactive. Inhibitors of p38 mitogen-activated protein kinase and PI3-kinase antagonized eosinophil shape change responses and chemotaxis of transfectants to CCL11 and CCL13. In contrast, shape change but not chemotaxis was sensitive to inhibition of the extracellular signal-regulated kinase kinase pathway suggesting differential regulation of the two responses. Thus, the CCR3 C terminus contains distinct domains responsible for the regulation of receptor desensitization and for coupling to chemotactic responses.

  3. 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.

  4. BIOCHEMICAL CYTOLOGY OF TRICHOMONAD FLAGELLATES

    PubMed Central

    Müller, Miklós

    1973-01-01

    To determine the localization of several enzymes in Tritrichomonas foetus, the axenic KV-1 strain was grown in Diamond's medium with bovine serum, homogenized in 0.25 M sucrose, and subjected to analytical differential and isopycnic centrifugation. The fractions were assayed for their enzymatic composition and examined electron microscopically. NADH and NADPH dehydrogenases, about 90% of the catalase, and two hydrolases, α-galactosidase and manganese-activated β-galactosidase I are in the nonsedimentable part of the cytoplasm. α-Glycerophosphate and malate dehydrogenases are associated with a large particle, whose equilibrium density in sucrose gradients is 1.24. This particle corresponds to that population of the paracostal and paraxostylar granules which, having a uniform granular matrix surrounded by a single membrane, resemble microbodies from other organisms. The small sedimentable portion of catalase (about 10% of the total activity) is not associated with these granules and equilibrates at density 1.22. The nature of the subcellular entity carrying catalase could not be ascertained. Hydrolases with a pH optimum around 6–6.5 (protease, β-N-acetylglucosaminidase, β-N-acetylgalactosaminidase, and cation-independent β-galactosidase II), as well as a large part of acid phosphatase, are associated with a population of large particles which equilibrate at densities from 1.15 to 1.20. The hydrolases in these granules lose their structure-bound latency easily after freezing and thawing. These particles correspond to another population of the paracostal and paraxostylar granules which have varied shape and inhomogeneous content with frequent myelin figures, indicating a digestive function. The rest of the phosphatase and most of the acid β-glucuronidase activity are in a smaller granule fraction with an equilibrium density around 1.18. The latency of these enzymes is quite resistant to freezing and thawing. This particle population consists of smaller, very often flattened vesicles and granules, many of which are clearly fragments of the prominent Golgi apparatus of the cell. PMID:4144506

  5. 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

  6. Cloning, purification, crystallization and X-ray crystallographic analysis of the periplasmic sensing domain of Pseudomonas fluorescens chemotactic transducer of amino acids type A (CtaA).

    PubMed

    Ud-Din, Abu Iftiaf Md Salah; Roujeinikova, Anna

    2016-09-05

    Chemotaxis towards nutrients plays a crucial role in root colonization by Pseudomonas fluorescens. The P. fluorescens chemotactic transducer of amino acids type A (CtaA) mediates movement towards amino acids present in root exudates. In this study, the periplasmic sensory domain of CtaA has been crystallized by the hanging-drop vapor diffusion method using ammonium sulfate as a precipitating agent. A complete data set was collected to 1.9 Å resolution using cryocooling conditions and synchrotron radiation. The crystals belong to space group I222 or I212121, with unit-cell parameters a = 67.2, b = 76.0, c = 113.3 Å. This is an important step towards elucidation of the structural basis of how CtaA recognizes its signal molecules and transduces the signal across the membrane.

  7. Chemotactic responses of Dictyostelium discoideum amoebae to a cyclic AMP concentration gradient: evidence to support a spatial mechanism for sensing cyclic AMP.

    PubMed

    Tani, T; Naitoh, Y

    1999-01-01

    The motile responses of Dictyostelium discoideum amoebae to a cyclic AMP (cAMP) concentration gradient were examined using a novel assay system. In this system, a cAMP concentration gradient was generated, while the overall cAMP concentration could be either increased or decreased in a chamber containing amoebae. The chemotactic responses of amoebae were examined immediately after they had been subjected to the cAMP concentration gradient. Amoebae moving in random directions in a reference solution ascended a cAMP concentration gradient after they had been exposed to the gradient irrespective of whether there was an increase or a decrease in the overall cAMP concentration. This strongly supports the idea that D. discoideum amoebae can sense a spatial cAMP gradient around them and that this causes their chemoaccumulation behavior. Ascending locomotion became less conspicuous when the amoebae were treated with a homogeneous cAMP solution for approximately 8 min before exposure to a cAMP gradient. This cAMP pretreatment reduced the sensitivity of the amoeba to a cAMP concentration gradient. The cAMP concentration gradient could be reversed in less than 30 s in this assay system, allowing the generation of a cAMP wave by accumulating amoebae to be mimicked. The ascending amoebae continued to move in the same direction for 1-2 min after the gradient had been reversed. This is consistent with the well-known observation that reversal of a cAMP concentration gradient experienced by the amoebae passing through a cAMP wave does not negate their chemotactic movement towards the accumulation center.

  8. 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 Central

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

    2012-01-01

    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+Actinhigh. In contrast, CD45RA T cells are phenotypically CD45RA+Actinlow. 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

  9. Characteristic Time Scales of Transport Processes for Chemotactic Bacteria in Groundwater: Analysis of Pore-scale to Field-scale Experimental Data

    NASA Astrophysics Data System (ADS)

    Ford, R. M.

    2010-12-01

    Many processes contribute to the transport of microorganisms in groundwater environments. One process of interest is chemotaxis, whereby motile bacteria are able to detect and swim toward increasing concentrations of industrial hydrocarbons that they perceive as food sources. By enabling bacteria to migrate to the sources of pollutants that they degrade, chemotaxis has the potential to enhance bioremediation efforts, especially in less permeable zones where contamination may persist. To determine the field conditions under which chemotaxis might be exploited in a bioremediation scheme requires an understanding of the characteristic time scales in the system. We defined a dimensionless chemotaxis number that compares the time over which a bacterial population is exposed to a chemical gradient to the time required for a bacterial population to migrate a significant distance in response to a chemical gradient. The exposure time and the response time are dependent upon the experimental conditions and properties of the bacteria and chemical attractant. Experimental data was analyzed for a range of groundwater flow rates over a wide scope of experimental systems including a single-pore with NAPL source, a microfluidic channel with and without a porous matrix, a laboratory column, a bench-scale microcosm and a field-scale study. Chemical gradients were created transverse to the flow direction. Distributions of chemotactic and nonchemotactic bacteria were compared to determine the extent of migration due to chemotaxis. Under some conditions at higher flow rates, the effect of chemotaxis was diminished to the point of not being detected. The goal of the study was to determine a critical value for the dimensionless chemotaxis number (which is independent of scale) that can be used as a design criterion to ascertain a priori the conditions under which a chemotactic response will impact bacterial transport relative to other processes such as advection and dispersion.

  10. UDP-Induced Phagocytosis and ATP-Stimulated Chemotactic Migration Are Impaired in STIM1−/− Microglia In Vitro and In Vivo

    PubMed Central

    Lim, Hye Min; Woon, Heo; Han, Jung Woo; Baba, Yoshihiro; Kurosaki, Tomohiro; Lee, Min Goo

    2017-01-01

    STIM1 is the only currently known intracellular calcium sensor that functions as the calcium influx regulator controlling immune cell activation. STIM1 function in immune cell calcium signalling has been studied extensively; however, its role in microglia, innate immune cells in brain, has not been fully understood. Here, we report that STIM1−/− murine microglia lost store-operated calcium influx and displayed aberrant immunological functions. Microglial functions regulated by chronic and global [Ca2+]i changes were reduced significantly, including cytokine releases and opsonin-dependent phagocytosis. More dramatically, cellular functions governed by Ca2+ regulation in local microdomains at the cell periphery, such as UDP-induced phagocytosis and ATP-stimulated chemotactic migration, were severely reduced in STIM1−/− microglia. Interestingly, UDP-induced Orai1 mobilization to the peripheral region was greatly attenuated in STIM1−/− microglia. Their chemotactic migration defect was reproduced in vivo in embryonic brain; the aggregated number of STIM1−/− microglia in LPS- (lipopolysaccharide-) injected lesions was much smaller than that in wild-type microglia. Furthermore, the neuron phagoptosis activities of activated microglia were significantly diminished in the STIM1−/− microglia. These in vitro and in vivo results suggest that STIM1-mediated store-operated calcium entry is important for the regulation of global [Ca2+]i changes which differentiates into active immune state of microglia, but it is more crucial for the regulation of local [Ca2+] microdomains which mediates the acute motility of murine microglia. PMID:28293066

  11. The strength of the chemotactic response to a CCR5 binding chemokine is determined by the level of cell surface CCR5 density.

    PubMed

    Desmetz, Caroline; Lin, Yea-Lih; Mettling, Clément; Portalès, Pierre; Rabesandratana, Herisoa; Clot, Jacques; Corbeau, Pierre

    2006-12-01

    We have shown that the intensity of expression of the C-C chemokine receptor CCR5 at the single CD4(+) cell level strongly determines the efficiency of its function as a coreceptor for human immunodeficiency virus type 1. By analogy, we examined if the number of CCR5 molecules at the cell surface might determine its chemotactic response to CCR5 ligands. To test this hypothesis, we measured by flow cytometry the migration of primary human T cells towards the CCR5-binding chemokine CCL5 in vitro. First, we observed a dose-dependent blockage of this migration exerted by an anti-CCR5 monoclonal antibody. Second, we sorted peripheral blood mononuclear cells into five subpopulations expressing various cell surface CCR5 densities, and observed a correlation between the intensity of migration towards CCL5 and the level of CCR5 expression on these subpopulations. Third, we transduced CCR5(+) peripheral blood mononuclear cells with the CCR5 gene, and observed that the CCR5 over-expression induced an over-migration towards CCL5. Finally, we observed in healthy donors a correlation between the chemotactic response of peripheral blood CD8(+) T cell to CCL5 and their level of surface CCR5 expression. T-cell surface CCR5 density, which is constant over time for a given individual, but varies drastically among individuals, might therefore be an important personal determinant of T-cell migration in many biological situations where CCR5-binding chemokines play a role, such as graft rejection, T helper 1-mediated auto-immune diseases, and infectious diseases involving CCR5. Moreover, our data highlight the therapeutic potential of CCR5 antagonists in these situations.

  12. The Major Leukocyte Chemotactic and Activating Factors in the Mouse Gut Lumen are not N-formylpeptide Receptor 1 (Fpr1) Agonists

    PubMed Central

    Ojode, Teresa; Schneider, Erich H.; Tiffany, H. Lee; Yung, Sunny; Gao, Ji-Liang; Murphy, Philip M.

    2013-01-01

    Cultured bacteria release N-formylpeptides, which are potent chemoattractants for phagocytic leukocytes acting at G protein-coupled receptors FPR1 and FPR2. However, the distribution and immunologic activity of these molecules at mucosal surfaces, where large numbers of bacteria are separated from the immune system by epithelium, remain undefined. To investigate this for the gut, we tested leukocyte responses to cell-free gut luminal contents from C57Bl/6 mice fed a chow diet. Small and large intestine contents were able to compete with labeled N-formylpeptide for binding to FPR1, indicating the presence of FPR1 ligands in the gut lumen. Material from both small and large intestine induced robust calcium flux responses by primary FPR1+ leukocytes (mouse bone marrow cells and splenocytes, and human peripheral blood neutrophils and mononuclear cells), as well as chemotactic responses by both mouse bone marrow cells and human peripheral blood neutrophils. However, unlike defined N-formylpeptides, calcium flux responses induced by gut luminal contents were insensitive both to pertussis toxin treatment of leukocytes and to proteinase K digestion of the samples. Moreover, the gut samples were fully active on neutrophils from mice lacking Fpr1, and the kinetics of the calcium flux response differed markedly for neutrophils and PBMCs. The active factor(s) could be dialyzed using a 3.5 kD pore size membrane. Thus, mouse intestinal lumen contains small, potent and highly efficacious leukocyte chemotactic and activating factors that may be distinct for neutrophils and PBMCs and distinct from Fpr1 agonists. PMID:22722599

  13. 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.

  14. Sphingosine-1-phosphate inhibits PDGF-induced chemotaxis of human arterial smooth muscle cells: spatial and temporal modulation of PDGF chemotactic signal transduction

    PubMed Central

    1995-01-01

    Activation of the PDGF receptor on human arterial smooth muscle cells (SMC) induces migration and proliferation via separable signal transduction pathways. Sphingosine-1-phosphate (Sph-1-P) can be formed following PDGF receptor activation and therefore may be implicated in PDGF-receptor signal transduction. Here we show that Sph-1-P does not significantly affect PDGF-induced DNA synthesis, proliferation, or activation of mitogenic signal transduction pathways, such as the mitogen-activated protein (MAP) kinase cascade and PI 3-kinase, in human arterial SMC. On the other hand, Sph-1-P strongly mimics PDGF receptor-induced chemotactic signal transduction favoring actin filament disassembly. Although Sph-1-P mimics PDGF, exogenously added Sph-1-P induces more prolonged and quantitatively greater PIP2 hydrolysis compared to PDGF-BB, a markedly stronger calcium mobilization and a subsequent increase in cyclic AMP levels and activation of cAMP-dependent protein kinase. This excessive and prolonged signaling favors actin filament disassembly by Sph-1-P, and results in inhibition of actin nucleation, actin filament assembly and formation of focal adhesion sites. Sph-1-P-induced interference with the dynamics of PDGF-stimulated actin filament disassembly and assembly results in a marked inhibition of cell spreading, of extension of the leading lamellae toward PDGF, and of chemotaxis toward PDGF. The results suggest that spatial and temporal changes in phosphatidylinositol turnover, calcium mobilization and actin filament disassembly may be critical to PDGF-induced chemotaxis and suggest a possible role for endogenous Sph-1-P in the regulation of PDGF receptor chemotactic signal transduction. PMID:7790372

  15. Nucleus-encoded mRNAs for chloroplast proteins GapA, PetA, and PsbO are trans-spliced in the flagellate Euglena gracilis irrespective of light and plastid function.

    PubMed

    Mateášiková-Kováčová, Bianka; Vesteg, Matej; Drahovská, Hana; Záhonová, Kristína; Vacula, Rostislav; Krajčovič, Juraj

    2012-01-01

    Euglena gracilis is a fresh-water flagellate possessing secondary chloroplasts of green algal origin. In contrast with organisms possessing primary plastids, mRNA levels of nucleus-encoded genes for chloroplast proteins in E. gracilis depend on neither light nor plastid function. However, it remains unknown, if all these mRNAs are trans-spliced and possess spliced leader sequence at the 5'-end and if trans-splicing depends on light or functional plastids. This study revealed that polyadenylated mRNAs encoding the chloroplast proteins glyceraldehyde-3-phosphate dehydrogenase (GapA), cytochrome f (PetA), and subunit O of photosystem II (PsbO) are trans-spliced irrespective of light or plastid function.

  16. 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

  17. Preparation of Engineered Salmonella Typhimurium-Driven Hyaluronic-Acid-Based Microbeads with Both Chemotactic and Biological Targeting Towards Breast Cancer Cells for Enhanced Anticancer Therapy.

    PubMed

    Uthaman, Saji; Zheng, Shaohui; Han, Jiwon; Choi, Young Jin; Cho, Sunghoon; Nguyen, Van Du; Park, Jong-Oh; Park, Seung-Hwan; Min, Jung-Joon; Park, Sukho; Park, In-Kyu

    2016-01-21

    In this study, a new type of targeted bacteriobots is prepared and investigated as a therapeutic strategy against solid tumors. Maleimide-functionalized hyaluronic acid (HA) polymer is synthesized and cross-linked with four-arm-thiolated polyethylene glycol (PEG-SH) to form HA microbeads with diameter of 8 μm through the Michael-type addition. Docetaxel (DTX)-loaded nanoparticles are encapsulated in HA-PEG microbeads and sustained in vitro drug-release pattern of the DTX from the HA-PEG microbeads is observed for up to 96 h. Dual-targeted bacteriobots are prepared using CD 44 receptor-targeted HA microbeads synthesized via microfluidics, followed by the attachment of the flagellar bacterium Salmonella typhimurium, which have been genetically engineered for tumor targeting, onto the surface of the HA microbeads by the specific interaction between streptavidin on the HA beads and biotin on the bacteria. After the attachment of bacteria, the bacteriobots show an average velocity of 0.72 μm s(-1) and high chemotactic migration velocity of 0.43 μm s(-1) towards 4T1 cells lysates. CD 44 receptor-specific cellular uptake is verified through flow cytometry analysis and confocal imaging, demonstrating enhanced intracellular uptake in CD 44 receptor positive tumor cells compared to normal cells. Therefore, the present study suggests that these bacteriobots have dual-tumor-targeting abilities displaying their potential for targeted anticancer therapy.

  18. Novel sulfated glucomannan-barium-alginate microcapsules in islet transplantation: significantly decreased the secretion of monocyte chemotactic protein 1 and improved the activity of islet in rats.

    PubMed

    Chen, X; Zhang, L; Qi, Z; Guo, B; Zhong, L; Shen, B; Yan, Z; Zhang, J

    2009-12-01

    The sulfated glucomannan can be used to filter the heparin-binding properties of cytokines. In this study, novel sulfated glucomannan-barium-alginate (SGA) microcapsules were prepared to encapsulate islets with barium-alginate (ABa) and calcium alginate-poly-l-lysine (APA) microcapsules as controls. SD rat islets were purified as donor cells to Lewis rats that had been treated with streptozotocin. Intraperitoneal transplantation was performed with about 3000 islet equivalent (IEQ) rat. At week three after transplantation, the concentrations of monocyte chemotactic protein-1 (MCP-1), interleukin (IL)-1 beta, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha in intraperitoneal fluid were determined using ELISA. At week 8, the islet cell mass in the abdominal microcapsules was excised to test insulin release. The EB-FDA fluorescence staining method was used to observe the functional activity of the islet cells. Compared with ABa and APA microcapsules, SGA microcapsules showed significantly decreased MCP-1 secretion by beta-cells. Also, the concentrations of cytokines IL-1beta, IFN-gamma, and TNF-alpha were decreased significantly. The activity of the transplanted islets was significantly improved in SGA microcapsules, which shielded against cytokines better than ABa or APA microcapsules and may serve as novel method.

  19. Large induction of the chemotactic cytokine RANTES during cutaneous wound repair: a regulatory role for nitric oxide in keratinocyte-derived RANTES expression.

    PubMed Central

    Frank, S; Kämpfer, H; Wetzler, C; Stallmeyer, B; Pfeilschifter, J

    2000-01-01

    We investigated the role of NO on expressional regulation of the chemotactic cytokine RANTES (regulated upon activation, normal T-cell expressed and secreted) during tissue regeneration using an excisional wound-healing model in mice. Wound repair was characterized by a large and sustained induction of RANTES expression, and inhibition of inducible nitric oxide synthase (iNOS) during repair only slightly decreased RANTES expression levels. Immunohistochemical analysis revealed keratinocytes of the wound margins and the hyperproliferative epithelium to be the main RANTES-expressing cell type within the wound. Therefore we analysed the regulation of RANTES expression in vitro in cultured human keratinocytes of the cell line HaCaT. Here we demonstrate that NO very efficiently suppressed interleukin-1beta- and tumour-necrosis-factor-alpha-induced RANTES expression in keratinocytes. Furthermore, down-regulation of cytokine-induced RANTES mRNA in keratinocytes was dependent on endogenously produced NO, as inhibition of the co-induced iNOS by L-N(G)-monomethyl-L-arginine increased cytokine-triggered RANTES expression in the cells. Moreover, we observed strongest RANTES-immunopositive labelling in epithelial areas which were characterized by a NO-mediated low cellularity. Thus our data implicate NO as a negative regulator of RANTES expression during wound repair in vivo, as decreased numbers of keratinocytes observed in the absence of wound-derived NO might compensate for the high levels of RANTES expression which are associated with normal repair. PMID:10727427

  20. Intravenous immunoglobulin G (IVIG) inhibits IL-1- and TNF-α-dependent, but not chemotactic-factor-stimulated, neutrophil transendothelial migration.

    PubMed

    Issekutz, Andrew C; Rowter, Derek; Macmillan, Heather F

    2011-11-01

    High-dose intravenous immunoglobulin (IVIG) has anti-inflammatory effects via incompletely understood mechanisms. By investigating whether IVIG might modulate neutrophil (PMN) recruitment, we observed that IVIG dose-dependently inhibited (by 30-50%) PMN transendothelial migration (TEM) across human umbilical vein endothelial cells (EC) stimulated with IL-1α, IL-1β, TNF-α or IL-1β+TNF-α. Inhibition required the presence of IVIG with the responding PMNs, was attributable to the F(ab)(2) portion and was unrelated to putative contaminants in IVIG. IVIG did not inhibit IL-1β- or TNF-α-induced increase of PMN adhesion to EC, nor did it affect C5a- or IL-8-induced PMN TEM across unstimulated EC. Effects of IVIG and F(ab)(2) fragments were not associated with PMN activation, assessed by CD62L shedding, CD11b upregulation or PMN shape. Thus, IVIG selectively inhibits PMN TEM across inflammatory-cytokine-stimulated - but not unstimulated - EC, perhaps contributing to therapeutic benefit in chronic inflammation with minimal impact on chemotactic-factor-induced PMN recruitment during acute infection.

  1. Circulating histamine and neutrophil chemotactic activity during allergen-induced asthma: the effect of inhaled antihistamines and anti-allergic compounds.

    PubMed

    Morgan, D J; Moodley, I; Cundell, D R; Sheinman, B D; Smart, W; Davies, R J

    1985-07-01

    Plasma histamine and serum neutrophil chemotactic activity (S-NCA) were measured in ten atopic asthmatic patients on four separate occasions after allergen bronchial provocation testing (BPT). Single doses of inhaled sodium cromoglycate (SCG; 20 mg), clemastine (0.5 mg), ketotifen (0.5 mg) and isotonic saline (0.9% NaCl) placebo were administered 30 min before bronchial provocation testing in random order and double-blind. The airflow obstruction after BPT was monitored by measurement of forced expiratory volume in 1 s (FEV1). Plasma histamine was measured by the double-isotope radioenzymatic assay and S-NCA by a modified Boyden chamber technique. A highly significant decrease in FEV1 after BPT occurred on the placebo pre-treatment visit (P less than 0.001). Prior administration of inhaled SCG, clemastine and ketotifen significantly reduced the decrease in airflow obstruction seen after BPT when compared with placebo treatment (P less than 0.01, P less than 0.02, P less than 0.05 respectively). No significant alteration in plasma histamine was detected during allergen-induced airflow obstruction. Levels of S-NCA were significantly higher 5, 10 and 15 min after BPT when compared with the pre-challenge level (P less than 0.01, P less than 0.01, P less than 0.001 respectively). These levels were not significantly decreased when airflow obstruction was inhibited by the prior inhalation of SCG, clemastine or ketotifen.

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

    PubMed

    Rosier, Bob T; Lazova, Milena D

    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 attractant

  3. Tick saliva inhibits the chemotactic function of MIP-1alpha and selectively impairs chemotaxis of immature dendritic cells by down-regulating cell-surface CCR5.

    PubMed

    Oliveira, Carlo José F; Cavassani, Karen A; Moré, Daniela D; Garlet, Gustavo P; Aliberti, Julio C; Silva, João S; Ferreira, Beatriz R

    2008-05-01

    Ticks are blood-feeding arthropods that secrete immunomodulatory molecules through their saliva to antagonize host inflammatory and immune responses. As dendritic cells (DCs) play a major role in host immune responses, we studied the effects of Rhipicephalus sanguineus tick saliva on DC migration and function. Bone marrow-derived immature DCs pre-exposed to tick saliva showed reduced migration towards macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and regulated upon activation, normal T cell expressed and secreted (RANTES) chemokines in a Boyden microchamber assay. This inhibition was mediated by saliva which significantly reduced the percentage and the average cell-surface expression of CC chemokine receptor CCR5. In contrast, saliva did not alter migration of DCs towards MIP-3beta, not even if the cells were induced for maturation. Next, we evaluated the effect of tick saliva on the activity of chemokines related to DC migration and showed that tick saliva per se inhibits the chemotactic function of MIP-1alpha, while it did not affect RANTES, MIP-1beta and MIP-3beta. These data suggest that saliva possibly reduces immature DC migration, while mature DC chemotaxis remains unaffected. In support of this, we have analyzed the percentage of DCs on mice 48h after intradermal inoculation with saliva and found that the DC turnover in the skin was reduced compared with controls. Finally, to test the biological activity of the saliva-exposed DCs, we transferred DCs pre-cultured with saliva and loaded with the keyhole limpet haemocyanin (KLH) antigen to mice and measured their capacity to induce specific T cell cytokines. Data showed that saliva reduced the synthesis of both T helper (Th)1 and Th2 cytokines, suggesting the induction of a non-polarised T cell response. These findings propose that the inhibition of DCs migratory ability and function may be a relevant mechanism used by ticks to subvert the immune response of the host.

  4. Roles of monocyte chemotactic protein 1 and nuclear factor-κB in immune response to spinal tuberculosis in a New Zealand white rabbit model.

    PubMed

    Guo, X H; Bai, Z; Qiang, B; Bu, F H; Zhao, N

    2017-02-20

    This study aimed to explore the roles of monocyte chemotactic protein 1 (MCP-1) and nuclear factor kappa B (NF-κB) in immune response to spinal tuberculosis in a New Zealand white rabbit model. Forty-eight New Zealand white rabbits were collected and divided into four groups: experimental group (n=30, spinal tuberculosis model was established), the sham group (n=15, sham operation was performed) and the blank group (n=3). The qRT-PCR assay and western blotting were applied to detect the mRNA and protein expressions of MCP-1 and NF-κB in peripheral blood. ELISA was used to measure serum levels of MCP-1, NF-κB, IFN-γ, IL-2, IL-4, and IL-10. Flow cytometry was adopted to assess the distributions of CD4+, CD8+ lymphocytes and CD4+ CD25+ Foxp3 lymphocyte subsets. Compared with the sham and blank groups, the mRNA and protein expressions of MCP-1 and NF-κB in the experimental group were significantly increased. The experimental group had lower serum levels of IL-2 and IFN-γ and higher serum level of IL-10 than the sham and blank groups. In comparison to the sham and blank groups, CD4+ T lymphocyte subsets percentage, CD4+/CD8+ ratio and CD4+ CD25+ Foxp3+ Tregs subsets accounting for CD4+ lymphocyte in the experimental group were lower, while percentage of CD8+ T lymphocyte subsets was higher. Our study provided evidence that higher expression of MCP-1 and NF-κB may be associated with decreased immune function of spinal tuberculosis, which can provide a new treatment direction for spinal tuberculosis.

  5. Expression and modulation of C5a receptor (CD88) on skin dendritic cells. Chemotactic effect of C5a on skin migratory dendritic cells.

    PubMed Central

    Morelli, A; Larregina, A; Chuluyán, I; Kolkowski, E; Fainboim, L

    1996-01-01

    Although it is known that dendritic cells (DC) migrate in response to inflammatory stimuli. There is little information about the expression of receptors for chemotactic factors on DC. The present study has demonstrated by double immunostaining and flow cytometry of Langerhan's cell (LC)-enriched epidermal cell suspensions that a small subpopulation (5-6%) of epidermal resident DC (rLC) expresses receptors for C5a (C5aR). Epidermal rLC positive for C5aR show a round-shape morphology, were located next to the basement membrane and express HLA-DR molecules higher than C5aR negative rLC. These observations suggest that rLC would express C5aR as part of their process of maturation during tissue trafficking. To investigate whether epidermal LC up-regulate C5aR along their differentiation pathway. LC were differentiated in vitro after culture in epidermal cell suspensions supplemented with granulocyte macrophage colony-stimulating factor (GM-CSF). As a result, in vitro differentiated LC increased the expression of C5aR up to 69% of the DC population. In accordance with this observation, interdigitating DC of secondary lymphoid organs (lymph node and tonsil) also expressed (5aR. Migratory CD1a positive DC that spontaneously migrated out of dermal or split-skin organ explants were also positive for C5aR and were used for chemotaxis and chemokinesis assays in response to human recombinant C5a (rC5a). Optimum migration to rC5a was observed at 10(-8)M with a sigmoidal dose response curve. Checkboard analysis demonstrated that locomotion in response to rC5a was chemotaxis and not chemokinesis. Images Figure 3 Figure 6 Figure 7 Figure 10 Figure 11 PMID:8911150

  6. Characterization of synthetic human granulocyte chemotactic protein 2: usage of chemokine receptors CXCR1 and CXCR2 and in vivo inflammatory properties.

    PubMed

    Wuyts, A; Van Osselaer, N; Haelens, A; Samson, I; Herdewijn, P; Ben-Baruch, A; Oppenheim, J J; Proost, P; Van Damme, J

    1997-03-04

    Human granulocyte chemotactic protein 2 (GCP-2) has originally been isolated from cytokine-stimulated osteosarcoma cells as a chemokine coproduced in minute amounts together with interleukin 8. Human GCP-2 (75 residues) was synthesized on a 0.25-mmol scale using Fmoc chemistry. After disulfide bridge formation and purification, monomeric GCP-2 was recovered as a 6-kDa protein; the pure synthetic protein showed a molecular mass of 8076 Da as determined by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The exact amino acid sequence of synthetic GCP-2 was confirmed by Edman degradation. Synthetic GCP-2 was an equally active (minimal effective concentration of 1-3 nM) chemoattractant for neutrophilic granulocytes as was natural 75-residue GCP-2. At concentrations up to 30 nM, synthetic GCP-2 did not stimulate eosinophil, monocyte, or lymphocyte chemotaxis. GCP-2 induced a dose-dependent increase in [Ca2+]i in neutrophils, 1 nM being the minimal effective concentration. The GCP-2-induced [Ca2+]i increase was completely prevented by pertussis toxin. Prestimulation of neutrophils with equimolar concentrations of purified natural IL-8, GROalpha, GROgamma and ENA-78 abolished the [Ca2+]i increase in response to 1 nM GCP-2. Alternatively, the [Ca2+]i rise induced by these CXC chemokines was inhibited by pretreatment of neutrophils with GCP-2. GCP-2 stimulated [Ca2+]i increases in CXCR1- and CXCR2-transfected cells, demonstrating that GCP-2 binds to both IL-8 receptors. Intradermal injection of synthetic GCP-2 resulted in a dose-dependent neutrophil accumulation and plasma extravasation in rabbit skin. To provoke this skin reaction, GCP-2 (10 pmol/site) was nearly as effective as IL-8, indicating that it is an important complementary mediator of the inflammatory response.

  7. Roles of monocyte chemotactic protein 1 and nuclear factor-κB in immune response to spinal tuberculosis in a New Zealand white rabbit model

    PubMed Central

    Guo, X.H.; Bai, Z.; Qiang, B.; Bu, F.H.; Zhao, N.

    2017-01-01

    This study aimed to explore the roles of monocyte chemotactic protein 1 (MCP-1) and nuclear factor kappa B (NF-κB) in immune response to spinal tuberculosis in a New Zealand white rabbit model. Forty-eight New Zealand white rabbits were collected and divided into four groups: experimental group (n=30, spinal tuberculosis model was established), the sham group (n=15, sham operation was performed) and the blank group (n=3). The qRT-PCR assay and western blotting were applied to detect the mRNA and protein expressions of MCP-1 and NF-κB in peripheral blood. ELISA was used to measure serum levels of MCP-1, NF-κB, IFN-γ, IL-2, IL-4, and IL-10. Flow cytometry was adopted to assess the distributions of CD4+, CD8+ lymphocytes and CD4+ CD25+ Foxp3 lymphocyte subsets. Compared with the sham and blank groups, the mRNA and protein expressions of MCP-1 and NF-κB in the experimental group were significantly increased. The experimental group had lower serum levels of IL-2 and IFN-γ and higher serum level of IL-10 than the sham and blank groups. In comparison to the sham and blank groups, CD4+ T lymphocyte subsets percentage, CD4+/CD8+ ratio and CD4+ CD25+ Foxp3+ Tregs subsets accounting for CD4+ lymphocyte in the experimental group were lower, while percentage of CD8+ T lymphocyte subsets was higher. Our study provided evidence that higher expression of MCP-1 and NF-κB may be associated with decreased immune function of spinal tuberculosis, which can provide a new treatment direction for spinal tuberculosis. PMID:28225889

  8. Augmentation of monocyte chemotactic protein-1 and mRNA transcript in chronic inflammatory states induced by potassium permanganate (KMnO4) in vivo.

    PubMed Central

    Conti, P; Reale, M; Feliciani, C; Frydas, S; Trakatellis, M; Placido, F C; Cataldo, I; Di Gioacchino, M; Barbacane, R C

    1997-01-01

    Monocyte chemotactic protein-1 (MCP-1) is a proinflammatory cytokine that attracts and activates specific types of leucocytes. The purpose of this work was to analyse the generation of MCP-1 and mRNA transcript in a model of chronic inflammation using a granulomatous tissue induced by potassium permanganate (KMnO4; water soluble crystals). The data presented here shows that MCP-1 is generated in granuloma tissue and its level was strongly increased by i.p. injections of lipopolysaccharide (LPS) and inhibited in rats treated with injections of dexamethasone, 18 hr before the animals were killed. In histological studies LPS and dexamethasone increased and decreased, respectively, the recruitment of mononuclear cells in the granuloma tissue compared with the control granulomas from phosphate-buffered saline (PBS)-treated animals. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for mRNA extraction and cDNA synthesis. mRNA MCP-1 was significantly produced in the granuloma tissue of untreated animals, an effect increased by LPS and inhibited by dexamethasone, compared with the controls. Moreover, MCP-1 protein was found in the supernatant from homogenized granuloma tissues and the levels of MCP-1 were higher in the LPS-treated animals, while they were lower in the dexamethasone group, compared with the granulomas from the PBS-treated groups (control). The generation of MCP-1 was also found in minced granuloma tissue incubated for 18 hr (overnight) from treated (LPS or dexamethasone) and untreated (PBS) rats. When LPS was added in vitro for 18 hr to the controls and treated animals the production of MCP-1 was further increased except in the dexamethasone group (P > 0.05). Analysing blood serum from LPS, dexamethasone or PBS-treated rats, we found that MCP-1 was also present. The level was higher in the LPS group and lower in the dexamethasone group, compared with the control (PBS). In these studies we show for the first time that MCP-1 transcript and

  9. 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.

  10. The evolution and diversity of kinetoplastid flagellates.

    PubMed

    Simpson, Alastair G B; Stevens, Jamie R; Lukes, Julius

    2006-04-01

    Five years ago, little was known about kinetoplastid evolution. Recent improvements in the taxon sampling for nuclear rRNA genes and several protein markers have transformed this understanding. Parasitism evolved at least four times in kinetoplastids. Obligate parasitic trypanosomatids are a relatively 'derived' group within kinetoplastids; their closest relative is likely to be the free-living Bodo saltans, and the ancestral trypanosomatids were probably parasites of insects. Although subject to recent controversy, trypanosomes (genus Trypanosoma) probably constitute a monophyletic group. Several unusual features of trypanosomatid genomes (e.g. trans-splicing, mitochondrial RNA editing and intron poverty) are common in kinetoplastids and pre-date the adoption of parasitism. The framework of relationships is becoming robust enough for real comparative approaches to be used to understand kinetoplastid biology.

  11. 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.

  12. Effect of dietary polyphenols from hop (Humulus lupulus L.) pomace on adipose tissue mass, fasting blood glucose, hemoglobin A1c, and plasma monocyte chemotactic protein-1 levels in OLETF rats.

    PubMed

    Yui, Kazuki; Uematsu, Hiroki; Muroi, Keisuke; Ishii, Kazuhiro; Baba, Minako; Osada, Kyoichi

    2013-01-01

    Hop (Humulus lupulus L.) pomace contains procyanidin-rich polyphenols, which are large oligomeric compounds of catechin. We studied the effect of high dose (1%) of dietary hop pomace polyphenols (HPs) in Otsuka Long-EvansTokushima Fatty (OLETF) rats, an animal model of type 2 diabetes. By 70 days, the rats fed HPs tended to have a lower body weight and reduced mesenteric white adipose tissue weight than the rats fed a control diet. Triglyceride levels in both plasma and liver tended to be lower in the HPs-fed group than in the control group. Dietary HPs substantially suppressed the activities of hepatic fatty acid synthetase, glucose-6-phosphate dehydrogenase, and malic enzyme, through the suppression of SREBP1c mRNA expression in OLETF rats. Moreover, in the HPs-fed group, monocyte chemotactic protein-1 (MCP-1) expression and fasting blood glucose levels at 40 days, and hemoglobin A1c (HbA1c) levels at 70 days were significantly lower than those in the control group. Thus, dietary HPs may exert an ameliorative function on hepatic fatty acid metabolism, glucose metabolism, and inflammatory response accompanying the increase of the adipose tissue mass in OLETF rats.

  13. High concentrations of circulating interleukin-6 and monocyte chemotactic protein-1 with low concentrations of interleukin-8 were associated with severe chikungunya fever during the 2009-2010 outbreak in Thailand.

    PubMed

    Lohachanakul, Jindarat; Phuklia, Weerawat; Thannagith, Montri; Thonsakulprasert, Tipparat; Ubol, Sukathida

    2012-02-01

    The recent outbreak of Chikungunya virus in Thailand caused a rheumatic fever associated with considerable morbidity and fatalities. Thus, it is important to identify biomarker(s) of severe disease induced by this threatening arbovirus. Putative biomarkers in cases of chikungunya fever during an outbreak in the southern part of Thailand in 2009-2010 were identified. Sixty-two patients who had developed fever and myalgia, with or without arthralgia/arthritis, were enrolled and grouped into severe chikungunya fever (CHIKF) (n= 15), mild CHIKF (n= 20) and non-CHIKF (n= 27) to investigate circulating immunological mediators that might serve as markers of severity. Blood samples were taken at presentation (day 1) and 30 days later (day 30) and plasma concentrations of interleukin (IL)-1β, IL-6, IL-8, IL-17, tumor necrosis factor-alpha, monocyte chemotactic protein-1 (MCP-1), matrix metalloproteinase-1, tissue inhibitor of matrix metalloproteinase-1 and viral load were measured by ELISA. On day 1, severe CHIKF and mild CHIKF groups had viral loads of 10(8.5) and 10(8.3) of RNA copies/mL, respectively. At presentation, all CHIKF patients had circulating concentrations of IL-6 and MCP-1 higher than did non-CHIKF patients, whereas amongst the CHKF patients, the severe CHIKF patients had higher IL-6 concentrations than did mild CHIKF patients. Interestingly, severe CHIKF patients had significantly lower concentrations of circulating IL-8 than the other groups of patients, suggesting that high concentrations of IL-6 and MCP-1 with low concentrations of IL-8 may be a determinant of severe chikungunya virus infection.

  14. 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 Central

    Maudsley, D J; Morris, A G

    1987-01-01

    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

  15. 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

    Stein, J V; Rot, A; Luo, Y; Narasimhaswamy, M; Nakano, H; Gunn, M D; Matsuzawa, A; Quackenbush, E J; Dorf, M E; von Andrian, U H

    2000-01-03

    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 Galpha(i)-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 (T(GFP) cells). TCA-4 was constitutively presented on the luminal surface of HEVs, where it was required for LFA-1 activation on rolling T(GFP) cells. Desensitization of the TCA-4 receptor, CC chemokine receptor 7 (CCR7), blocked T(GFP) cell adherence in wild-type HEVs, whereas desensitization to stromal cell-derived factor (SDF)-1alpha (the ligand for CXC chemokine receptor 4 [CXCR4]) did not affect T(GFP) 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, T(GFP) 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 T(GFP) 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.

  16. Activated Membrane Patches Guide Chemotactic Cell Motility

    PubMed Central

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

    2011-01-01

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

  17. 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.

  18. Suppression of Chemotactic Explosion by Mixing

    NASA Astrophysics Data System (ADS)

    Kiselev, Alexander; Xu, Xiaoqian

    2016-11-01

    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.

  19. Multi-scale modeling of chemotactic interactions

    NASA Astrophysics Data System (ADS)

    Grima, Ramon

    Biological complexity emerges from the synthesis of biochemical, chemical and physical phenomena. In recent years there has been an intense effort in modeling various cellular systems of interest to understand how the observed complexity emerges from the underlying mechanisms. Most modeling approaches are based on a population description of the cells: these methods, though usually amenable to calculation, are only valid in the limit of large numbers of interacting cells. Many systems of interest involve the interaction of a relatively small number of cells; even biological systems composed of thousands of cells have spatially extended regions over which the number density of cells is small. For the latter cases, population descriptions are not valid and individual based models become a necessity. Such models, usually cellular automaton models, have been numerically studied in recent years; however, these models are not usually amenable to analytic calculation. The work presented in this thesis seeks to fulfill a gap in modeling approaches to the understanding of biocomplexity by constructing an individual based model on which analysis is possible, through the methods of statistical physics and the theory of stochastic processes. This model will be used to study the differences between individual based and population based models and the range of applicability of the latter. For the sake of comparison of the two, new efficient computational algorithms are devised for the simulation of both types of models. We finally complete our multiscale study of modeling by investigating the robustness of individual based models; this meaning a comparison of the results of different microscopic descriptions modeling the same underlying phenomena.

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

    USGS Publications Warehouse

    Ross, A.J.; Rucker, R.R.; Ewing, W.H.

    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.

  1. 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.

  2. 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.

  3. Characterization of protein-linked oligosaccharides in trypanosomatid flagellates.

    PubMed

    Mendelzon, D H; Previato, J O; Parodi, A J

    1986-03-01

    Protein-linked, endo-beta-N-acetylglucosaminidase H-sensitive oligosaccharides were isolated from several trypanosomatids incubated with [U-14C]glucose. Structural analysis of the compounds revealed that Man9GlcNAc2 was the oligosaccharide transferred from dolichol-P-P derivatives to proteins in Trypanosoma dionisii, Trypanosoma conorhini, Leptomonas samueli and Herpetomonas samuelpessoai and Man6GlcNAc2 in Blastocrithidia culicis and Leishmania adleri. In all cases, transiently glucosylated compounds were detected: Glc1Man7-9GlcNAc2 in T. dionisii, T. conorhini, L. samueli; Glc1Man9GlcNAc2 in H. samuelpessoai, Glc1Man6GlcNAc2 in B. culicis and Glc1Man6GlcNAc2 and Glc1Man5GlcNAc2 in L. adleri. The mechanism of protein glycosylation in T. dionisii and T. conorhini appeared to be similar to that described before for Trypanosoma cruzi epimastigotes, although some differences were found between the structures of the main isomers of Man7GlcNAc2 and Man8GlcNAc2 present in T. conorhini and T. cruzi. Differences between the mechanisms of glycosylation occurring in Leishmania mexicana and L. adleri were also found: Man6GlcNAc2 in the latter microorganism was demannosylated to Man5GlcNAc2, a step not detected in the former parasite. A novel substituent in N-linked high mannose-type oligosaccharides was found in L. samueli and H. samuelpessoai: galactose in the furanose configuration. In the latter trypanosomatid, Man9GlcNAc2 was demannosylated only to Man8GlcNAc2, whereas in all other parasites in which the same oligosaccharide was transferred to proteins, Man5-7GlcNAc2 were also detected.

  4. MECHANISM OF UTILIZATION OF CARBON SOURCES BY FLAGELLATED PROTOZOA.

    DTIC Science & Technology

    The transport of succinate into Euglena gracilis var bacillaris (streptomycin bleached) was investigated with the use of structural analogs and...Studies were begun on identification of the first products formed after succinate uptake. Coupled with this work was the finding that Euglena fixes...C02 may be intimately connected with succinate utilization by Euglena . With the finding of significant heterotrophic C02 fixation by Euglena (bleached

  5. 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.

  6. Chemotactic responses of tunicate (Urochordata, Ascidiacea) hemocytes in vitro.

    PubMed

    Raftos, D A; Stillman, D L; Cooper, E L

    1998-07-01

    A number of molecules were found to alter the motility of tunicate hemocytes. Bacterial lipopolysaccharide (LPS) significantly enhanced cell mobility relative to non-stimulated controls. Responses to LPS were not directional and so represented chemokinesis. In contrast, checkerboard analyses indicated that two tunicate hemolymph proteins, tunIL1-alpha and -beta, stimulated truly directional chemotaxis by hemocytes. The data suggest that tunIL1 proteins may contribute to defense by altering the localization of immunocompetent cells.

  7. 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 ...

  8. 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...

  9. Phase-field approach to chemotactic driving of neutrophil morphodynamics

    NASA Astrophysics Data System (ADS)

    Najem, Sara; Grant, Martin

    2013-09-01

    To simulate the motion of neutrophils and their morphodynamics in response to chemical cues, we construct a model based on the phase-field method utilizing a description with a free-energy functional and associated dynamics which captures the basic features of the phenomenon. We additionally incorporate spatial sensing by introducing an auxiliary field which depicts the polymerization of the region of the cell facing the highest concentration of the chemical attractant.

  10. Dynamics of formation of symmetrical patterns by chemotactic bacteria

    NASA Astrophysics Data System (ADS)

    Budrene, Elena O.; Berg, Howard C.

    1995-07-01

    MOTILE cells of Escherichia coli aggregate to form stable patterns of remarkable regularity when grown from a single point on certain substrates. Central to this self-organization is chemotaxis, the motion of bacteria along gradients of a chemical attractant that the cells themselves excrete1. Here we show how these complex patterns develop. The long-range spatial order arises from interactions between two multicellular aggregate structures: a 'swarm ring' that expands radially, and focal aggregates that have lower mobility. Patterning occurs through alternating domination by these two sources of excreted attractant (which we identify here as aspartate). The pattern geometries vary in a systematic way, depending on how long an aggregate remains active; this depends, in turn, on the initial concentration of substrate (here, succinate).

  11. Chemotactic behavior of the sperm of chitons (Mollusca: Polyplacophora).

    PubMed

    Miller, R L

    1977-11-01

    Observations of sperm behavior in the vicinity of gradients of egg-water or alcohol extracts of whole freshly-spawned eggs of several chitons reveal what appear to be directed movements of sperm up the gradient, resulting in the aggregation of motile sperm at the gradient source. Plots of the tracks of the sperm approaching the gradient source show that the cells increase the time during which they move toward the source and decrease the time spent moving away. Although this resembles the kinesis behavior shown by bacteria in a gradient, the path directions are markedly non-random. The reorientation behavior of thigmotactic sperm involves enlargement of the normal circular path diameter in the direction of the source and an alternation of tight loops and wide circular arcs, with the latter made in the direction of the source. The form of the path of attracted chiton sperm is like that observed during chemotaxis of the sperm of the hydroid Tubularia and the tunicate Ciona and resembles the behavior of Ciona sperm in that there is no increase in velocity as the cells move up the gradient. However, unlike the cnidarian and urochordate cases, the attracting substances extracted from chiton eggs do not act species-specifically.

  12. Chemotactic response of Helicobacter pylori to human plasma and bile.

    PubMed

    Worku, Mulugeta L; Karim, Q Najma; Spencer, John; Sidebotham, Ramon L

    2004-08-01

    To clarify further the role of chemotaxis in Helicobacter pylori colonization, the in vitro bacterium response to human plasma and bile (secretions containing chemoeffector compounds that are present in the gastric mucus layer) was examined. Human plasma, after dilution to 1 % (v/v) with buffer, was found to be a chemoattractant for the motile bacillus. Human gall-bladder bile, after dilution to 2 % (v/v) with buffer, was found to be a chemorepellent, but did not cause the motility of the bacillus to be diminished after prolonged exposure. The basis of the chemoattractant effect of plasma was explored by examining how urea and 12 amino acids found in plasma affected the taxis of H. pylori. Urea and the amino acids histidine, glutamine, glycine and arginine were the strongest chemoattractants. Other amino acids were chemoattractants, with the exceptions of aspartic and glutamic acids, which were chemorepellents. The basis of the chemorepellent effect of bile was explored by examining how the six most abundant conjugated bile acids in human bile affected the taxis of H. pylori. All the bile acids were chemorepellents, with the greatest effects being demonstrated by taurocholic and taurodeoxycholic acids. The implications of these findings for H. pylori colonization of gastric epithelium are discussed.

  13. Anomalous invasion in a 2d model of chemotactic predation

    NASA Astrophysics Data System (ADS)

    Willemsen, Jorge F.

    2010-09-01

    It has been hypothesized that plankton predators sense the presence of their prey through detection of chemical signals exuded by the prey. This process is formulated using elements of existing models, tailored to correspond to the specific process under investigation. The motivation for the resulting model is discussed in detail. Numerical results are then presented. It is found that the front representing the advance of the predator into the prey is irregular in a novel way, and the reasons for this anomalous invasion are discussed. It is recognized that reaction-diffusion models, starting perhaps with Turing, can lead to what might have been thought of as anomalous patterns - yet the “flicker” front advance discovered here is indeed novel.

  14. Noisy Oscillations in the Actin Cytoskeleton of Chemotactic Amoeba

    NASA Astrophysics Data System (ADS)

    Negrete, Jose; Pumir, Alain; Hsu, Hsin-Fang; Westendorf, Christian; Tarantola, Marco; Beta, Carsten; Bodenschatz, Eberhard

    2016-09-01

    Biological systems with their complex biochemical networks are known to be intrinsically noisy. Here we investigate the dynamics of actin polymerization of amoeboid cells, which are close to the onset of oscillations. We show that the large phenotypic variability in the polymerization dynamics can be accurately captured by a generic nonlinear oscillator model in the presence of noise. We determine the relative role of the noise with a single dimensionless, experimentally accessible parameter, thus providing a quantitative description of the variability in a population of cells. Our approach, which rests on a generic description of a system close to a Hopf bifurcation and includes the effect of noise, can characterize the dynamics of a large class of noisy systems close to an oscillatory instability.

  15. Bugs on a Slippery Plane : Understanding the Motility of Microbial Pathogens with Mathematical Modelling.

    PubMed

    Pushkin, Dmitri O; Bees, Martin A

    2016-01-01

    Many pathogenic microorganisms live in close association with surfaces, typically in thin films that either arise naturally or that they themselves create. In response to this constrained environment, the cells adjust their behaviour and morphology, invoking communication channels and inducing physical phenomena that allow for rapid colonization of biomedically relevant surfaces or the promotion of virulence factors. Thus, it is very important to measure and theoretically understand the key mechanisms for the apparent advantage obtained from swimming in thin films. We discuss experimental measurements of flows around a peritrichously flagellated bacterium constrained in a thin film, derive a simplified mathematical theory and Green's functions for flows in a thin film with general slip boundary conditions, and establish connections between theoretical and experimental results. This article aims to highlight the importance of mathematics as a tool to unlock qualitative mechanisms associated with experimental observations in the medical and biological sciences.

  16. Chlamydomonas swims with two "gears" in a eukaryotic version of run-and-tumble locomotion.

    PubMed

    Polin, Marco; Tuval, Idan; Drescher, Knut; Gollub, J P; Goldstein, Raymond E

    2009-07-24

    The coordination of eukaryotic flagella is essential for many of the most basic processes of life (motility, sensing, and development), yet its emergence and regulation and its connection to locomotion are poorly understood. Previous studies show that the unicellular alga Chlamydomonas, widely regarded as an ideal system in which to study flagellar biology, swims forward by the synchronous action of its two flagella. Using high-speed imaging over long intervals, we found a richer behavior: A cell swimming in the dark stochastically switches between synchronous and asynchronous flagellar beating. Three-dimensional tracking shows that these regimes lead, respectively, to nearly straight swimming and to abrupt large reorientations, which yield a eukaryotic version of the "run-and-tumble" motion of peritrichously flagellated bacteria.

  17. 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.

  18. 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.

  19. Cronobacter sakazakii ATCC 29544 Autoaggregation Requires FliC Flagellation, Not Motility

    PubMed Central

    Hoeflinger, Jennifer L.; Miller, Michael J.

    2017-01-01

    Cronobacter sakazakii is an opportunistic nosocomial and foodborne pathogen that causes severe infections with high morbidity and mortality rates in neonates, the elderly, and immunocompromised individuals. Little is known about the pathogenesis mechanism of this pathogen and if there are any consequences of C. sakazakii colonization in healthy individuals. In this study, we characterized the mechanisms of autoaggregation in C. sakazakii ATCC 29544 (CS29544). Autoaggregation in CS29544 occurred rapidly, within 30 min, and proceeded to a maximum of 70%. Frameshift mutations in two flagellum proteins (FlhA and FliG) were identified in two nonautoaggregating CS29544 clonal variant isolates. Strategic gene knockouts were generated to determine if structurally intact and functional flagella were required for autoaggregation in CS29544. All structural knockouts (ΔflhA, ΔfliG, and ΔfliC) abolished autoaggregation, whereas the functional knockout (ΔmotAB) did not prevent autoaggregation. Complementation with FliC (ΔfliC/cfliC) restored autoaggregation. Autoaggregation was also disrupted by the addition of exogenous wild-type CS29544 filaments in a dose-dependent manner. Finally, filament supercoils tethering neighboring wild-type CS29544 cells together were observed by transmission electron microscopy. In silico analyses suggest that direct interactions of neighboring CS29544 FliC filaments proceed by hydrophobic bonding between the externally exposed hypervariable regions of the CS29544 FliC flagellin protein. Further research is needed to confirm if flagella-mediated autoaggregation plays a prominent role in C. sakazakii pathogenesis. PMID:28293226

  20. SALINITY TOLERANCES OF 62 STRAINS OF PFIESTERIA AND PFIESTERIA-LIKE HETEROTROPHIC FLAGELLATES (DINOPHYCEAE). (R826793)

    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. Complete Genome of Ignavibacterium album, a Metabolically Versatile, Flagellated, Facultative Anaerobe from the Phylum Chlorobi.

    PubMed

    Liu, Zhenfeng; Frigaard, Niels-Ulrik; Vogl, Kajetan; Iino, Takao; Ohkuma, Moriya; Overmann, Jörg; Bryant, Donald A

    2012-01-01

    Prior to the recent discovery of Ignavibacterium album (I. album), anaerobic photoautotrophic green sulfur bacteria (GSB) were the only members of the bacterial phylum Chlorobi that had been grown axenically. In contrast to GSB, sequence analysis of the 3.7-Mbp genome of I. album shows that this recently described member of the phylum Chlorobi is a chemoheterotroph with a versatile metabolism. I. album lacks genes for photosynthesis and sulfur oxidation but has a full set of genes for flagella and chemotaxis. The occurrence of genes for multiple electron transfer complexes suggests that I. album is capable of organoheterotrophy under both oxic and anoxic conditions. The occurrence of genes encoding enzymes for CO(2) fixation as well as other enzymes of the reductive TCA cycle suggests that mixotrophy may be possible under certain growth conditions. However, known biosynthetic pathways for several amino acids are incomplete; this suggests that I. album is dependent upon on exogenous sources of these metabolites or employs novel biosynthetic pathways. Comparisons of I. album and other members of the phylum Chlorobi suggest that the physiology of the ancestors of this phylum might have been quite different from that of modern GSB.

  2. Eight unique basal bodies in the multi-flagellated diplomonad Giardia lamblia.

    PubMed

    McInally, Shane G; Dawson, Scott C

    2016-01-01

    Giardia lamblia is an intestinal parasitic protist that causes significant acute and chronic diarrheal disease worldwide. Giardia belongs to the diplomonads, a group of protists in the supergroup Excavata. Diplomonads are characterized by eight motile flagella organized into four bilaterally symmetric pairs. Each of the eight Giardia axonemes has a long cytoplasmic region that extends from the centrally located basal body before exiting the cell body as a membrane-bound flagellum. Each basal body is thus unique in its cytological position and its association with different cytoskeletal features, including the ventral disc, axonemes, and extra-axonemal structures. Inheritance of these unique and complex cytoskeletal elements is maintained through basal body migration, duplication, maturation, and their subsequent association with specific spindle poles during cell division. Due to the complex composition and inheritance of specific basal bodies and their associated structures, Giardia may require novel basal body-associated proteins. Thus, protists such as Giardia may represent an undiscovered source of novel basal body-associated proteins. The development of new tools that make Giardia genetically tractable will enable the composition, structure, and function of the eight basal bodies to be more thoroughly explored.

  3. 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...

  4. Ribosomal RNA phylogeny of bodonid and diplonemid flagellates and the evolution of euglenozoa.

    PubMed

    von der Heyden, Sophie; Chao, Ema E; Vickerman, Keith; Cavalier-Smith, Thomas

    2004-01-01

    Euglenozoa is a major phylum of excavate protozoa (comprising euglenoids, kinetoplastids, and diplonemids) with highly unusual nuclear, mitochondrial, and chloroplast genomes. To improve understanding of euglenozoan evolution, we sequenced nuclear small-subunit rRNA genes from 34 bodonids (Bodo, Neobodo, Parabodo, Dimastigella-like, Rhynchobodo, Rhynchomonas, and unidentified strains), nine diplonemids (Diplonema, Rhynchopus), and a euglenoid (Entosiphon). Phylogenetic analysis reveals that diplonemids and bodonids are more diverse than previously recognised, but does not clearly establish the branching order of kinetoplastids, euglenoids, and diplonemids. Rhynchopus is holophyletic; parasitic species arose from within free-living species. Kinetoplastea (bodonids and trypanosomatids) are robustly holophyletic and comprise a major clade including all trypanosomatids and most bodonids ('core bodonids') and a very divergent minor one including Ichthyobodo. The root of the major kinetoplastid clade is probably between trypanosomatids and core bodonids. Core bodonids have three distinct subclades. Clade 1 has two distinct Rhynchobodo-like lineages; a lineage comprising Dimastigella and Rhynchomonas; and another including Cruzella and Neobodo. Clade 2 comprises Cryptobia/ Trypanoplasma, Procryptobia, and Parabodo. Clade 3 is an extensive Bodo saltans species complex. Neobodo designis is a vast genetically divergent species complex with mutually exclusive marine and freshwater subclades. Our analysis supports three phagotrophic euglenoid orders: Petalomonadida (holophyletic), Ploeotiida (probably holophyletic), Peranemida (paraphyletic).

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

    PubMed

    Arora, Sucheta; Bhat, Vidya; Mittal, Aditya

    2007-08-15

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

  6. 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.

  7. Two components of photoreceptor potential in phototaxis of the flagellated green alga Haematococcus pluvialis

    PubMed Central

    Sineshchekov, Oleg A.; Litvin, Felix F.; Keszthelyi, Lajos

    1990-01-01

    The kinetics of the photoreceptor potential of phototaxis in biflagellated green alga Haematococcus pluvialis in response to a 10-ns laser pulse of three wavelengths (465, 550, and 590 nm) were measured in single cells with 30 μs time resolution. The rise and the decay of photoinduced potential are both at least biphasic. The first component of the rise is very stable and has no measurable (<30 μs) time delay. The second component is triggered after a 120-400-μs lag period, depending on flash intensity. Its appearance is sensitive to the physiological state of the cell and the amplitude can be increased by phototactically ineffective red background illumination. The electrical generators for both components are localized in the same region of the cell membrane (on the stigma-bearing side) and these components have the same depolarizing sign. The results indicate that the photoreceptor potential in phototaxis comprises two components, which could be interpreted as light-induced charge movement within the photoreceptor molecules and changes in ion permeability of the cell membrane. PMID:19431753

  8. 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.

  9. 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

  10. The swimming behavior of flagellated bacteria in viscous and viscoelastic media

    NASA Astrophysics Data System (ADS)

    Qu, Zijie; Henderikx, Rene; Breuer, Kenneth

    2016-11-01

    The motility of bacteria E.coli in viscous and viscoelastic fluids has been widely studied although full understanding remains elusive. The swimming mode of wild-type E.coli is well-described by a run-and-tumble sequence in which periods of straight swimming at a constant speed are randomly interrupted by a tumble, defined as a sudden change of direction with a very low speed. Using a tracking microscope, we follow cells for extended periods of time and find that the swimming behavior can be more complex, and can include a wider variety of behaviors including a "slow random walk" in which the cells move at relatively low speed without the characteristic run. Significant variation between individual cells is observed, and furthermore, a single cell can change its motility during the course of a tracking event. Changing the viscosity and viscoelasticy of the swimming media also has profound effects on the average swimming speed and run-tumble nature of the cell motility, including changing the distribution, duration of tumbling and slow random walk events. The reasons for these changes are explained using a Purcell-style resistive force model for the cell and flagellar behavior as well as model for the changes in flagellar bundling in different fluid viscosities. National Science Foundation.

  11. UV-B affects photosynthesis, ROS production and motility of the freshwater flagellate, Euglena agilis Carter.

    PubMed

    Kottuparambil, Sreejith; Shin, Woongghi; Brown, Murray T; Han, Taejun

    2012-10-15

    The effects of ultraviolet B (UV-B; 295-320 nm) radiation on certain vital physiological (photosynthesis), biochemical (production of reactive oxygen species - ROS) and behavioral (motility and orientation) characteristics were investigated in the unicellular photoautotroph, Euglena agilis Carter. The photosynthetic performance of E. agilis was recorded after exposure of between 15 and 60 min followed by a period of recovery lasting 6-24h under dim light (5-10 μmol photons m(-2) s(-1)). The maximum quantum yield of PS II (F(v)/F(m)) was reduced to 65% and 14% of initial values immediately following 15 and 30 min UV-B exposure, but recovered to 100 and 86% of the initials, respectively. Values of rETR(max) in E. agilis exposed to 15 min UV-B were similar to those of the initials, but a 30 min UV exposure resulted in 75% reduction of rETR(max) with only a 43% recovery as compared with the initial after 24h recovery. After a 60 min UV-B exposure, there were no Chl a fluorescence signals, and hence no F(v)/F(m) or rETR(max). A UV dose-dependent increase in DCFH-DA fluorescence was found in E. agilis cells, reflecting an increase in ROS production. After exposures to UV-B for between 15 and 60 min, the percentages of motile cells in the population decreased to 76, 39 and 15%, respectively. Following 24h in dim light, the percentage of motile cells increased to between 66% and 95% of the initial value. The velocity of non-irradiated cells was 60 μm s(-1), which decreased to 16-35 μm s(-1) immediately following exposure for 15-60 min. After periods of time in dim light (6, 12 and 24h) velocities had recovered to between 44 and 81% of the initial value. In untreated controls, the r-value was 0.23, indicating random movement of E. agilis, but it increased to 0.35 and 0.72 after exposure to UV-B for 30 and 60 min, respectively. There was a tendency towards vertical downward movement of cells proportional to the duration of exposure. The compactness of E. agilis decreased from 2.9 in controls to 1.8-2.3 in cells treated with UV-B although significant recovery followed. UV-B dose-dependent interaction between photosynthetic activity, ROS production and movement is discussed in terms of a UV-protective mechanism in E. agilis.

  12. Chronic toxicity of a laundry detergent to the freshwater flagellate Euglena gracilis.

    PubMed

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

    2012-10-01

    Chronic toxicity of the common laundry detergent Ariel on the freshwater alga Euglena gracilis was investigated by growing the alga in a medium containing the detergent for 7 days. Cell density, motility, swimming velocity, gravitactic orientation, cell shape, photosynthesis and concentration of light-harvesting pigments were used as end point parameters for the assessment of toxicity. Cell density was significantly reduced at a concentration of 1 mg l(-1) or above. Among the other tested parameters, with the exception of cell shape, gravitaxis and chlorophyll b, all were adversely affected by the detergent at concentrations exceeding 1 mg l(-1). It is concluded that long-term (7-days) exposure to the detergent caused significant toxicity to E. gracilis. Furthermore, long-term tests with E. gracilis can be used as sensitive indicator for the toxicity assessment of laundry detergents in aquatic environments.

  13. 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

    2014-03-03

    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.

  14. 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.

  15. 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

  16. FlhF, a signal recognition particle-like GTPase, is involved in the regulation of flagellar arrangement, motility behaviour and protein secretion in Bacillus cereus.

    PubMed

    Salvetti, Sara; Ghelardi, Emilia; Celandroni, Francesco; Ceragioli, Mara; Giannessi, Francesco; Senesi, Sonia

    2007-08-01

    Flagellar arrangement is a highly conserved feature within bacterial species. However, only a few genes regulating cell flagellation have been described in polar flagellate bacteria. This report demonstrates that the arrangement of flagella in the peritrichous flagellate Bacillus cereus is controlled by flhF. Disruption of flhF in B. cereus led to a reduction in the number of flagella from 10-12 to 1-3 filaments per cell in the insertion mutant MP06. Moreover, compared to the parental strain, MP06 exhibited: (i) shorter smooth swimming phases, causing reduced swimming motility but not affecting chemotaxis; (ii) complete inhibition of swarming motility, as differentiated swarm cells were never detected; (iii) an increased amount of extracellular proteins; and (iv) differential export of virulence determinants, such as haemolysin BL (HBL), phosphatidylcholine-preferring phospholipase C (PC-PLC) and non-haemolytic enterotoxin (NHE). Introduction of a plasmid harbouring flhF (pDGflhF) into MP06 completely restored the wild-type phenotype in the trans-complemented strain MP07. B. cereus flhF was found to constitute a monocistronic transcriptional unit and its overexpression did not produce abnormal features in the wild-type background. Characterization of a B. cereus mutant (MP05) carrying a partial flhF deletion indicated that the last C-terminal domain of FlhF is involved in protein export while not required for flagellar arrangement and motility behaviour. Taken together, these data suggest that B. cereus FlhF is a promising candidate for connecting diverse cellular functions, such as flagellar arrangement, motility behaviour, pattern of protein secretion and virulence phenotype.

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

    PubMed

    Moreno-Arotzena, O; Mendoza, G; Cóndor, M; Rüberg, T; García-Aznar, J M

    2014-11-01

    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.

  18. Onset of nonlinearity in a stochastic model for auto-chemotactic advancing epithelia.

    PubMed

    Ben Amar, Martine; Bianca, Carlo

    2016-09-27

    We investigate the role of auto-chemotaxis in the growth and motility of an epithelium advancing on a solid substrate. In this process, cells create their own chemoattractant allowing communications among neighbours, thus leading to a signaling pathway. As known, chemotaxis provokes the onset of cellular density gradients and spatial inhomogeneities mostly at the front, a phenomenon able to predict some features revealed in in vitro experiments. A continuous model is proposed where the coupling between the cellular proliferation, the friction on the substrate and chemotaxis is investigated. According to our results, the friction and proliferation stabilize the front whereas auto-chemotaxis is a factor of destabilization. This antagonist role induces a fingering pattern with a selected wavenumber k0. However, in the planar front case, the translational invariance of the experimental set-up gives also a mode at k = 0 and the coupling between these two modes in the nonlinear regime is responsible for the onset of a Hopf-bifurcation. The time-dependent oscillations of patterns observed experimentally can be predicted simply in this continuous non-linear approach. Finally the effects of noise are also investigated below the instability threshold.

  19. Moving towards a paradigm: Common mechanisms of chemotactic signaling in Dictyostelium and mammalian leukocytes

    PubMed Central

    Artemenko, Yulia; Lampert, Thomas J.; Devreotes, Peter N.

    2014-01-01

    Chemotaxis, or directed migration of cells along a chemical gradient, is a highly coordinated process that involves gradient sensing, motility, and polarity. Most of our understanding of chemotaxis comes from studies of cells undergoing amoeboid-type migration, in particular the social amoeba Dictyostelium discoideum and leukocytes. In these amoeboid cells the molecular events leading to directed migration can be conceptually divided into four interacting networks: receptor/G protein, signal transduction, cytoskeleton, and polarity. The signal transduction network occupies a central position in this scheme as it receives direct input from the receptor/G protein network, as well as feedback from the cytoskeletal and polarity networks. Multiple overlapping modules within the signal transduction network transmit the signals to the actin cytoskeleton network leading to biased pseudopod protrusion in the direction of the gradient. The overall architecture of the networks, as well as the individual signaling modules are remarkably conserved between Dictyostelium and mammalian leukocytes, and the similarities and differences between the two systems are the subject of this review. PMID:24846395

  20. Onset of nonlinearity in a stochastic model for auto-chemotactic advancing epithelia

    PubMed Central

    Ben Amar, Martine; Bianca, Carlo

    2016-01-01

    We investigate the role of auto-chemotaxis in the growth and motility of an epithelium advancing on a solid substrate. In this process, cells create their own chemoattractant allowing communications among neighbours, thus leading to a signaling pathway. As known, chemotaxis provokes the onset of cellular density gradients and spatial inhomogeneities mostly at the front, a phenomenon able to predict some features revealed in in vitro experiments. A continuous model is proposed where the coupling between the cellular proliferation, the friction on the substrate and chemotaxis is investigated. According to our results, the friction and proliferation stabilize the front whereas auto-chemotaxis is a factor of destabilization. This antagonist role induces a fingering pattern with a selected wavenumber k0. However, in the planar front case, the translational invariance of the experimental set-up gives also a mode at k = 0 and the coupling between these two modes in the nonlinear regime is responsible for the onset of a Hopf-bifurcation. The time-dependent oscillations of patterns observed experimentally can be predicted simply in this continuous non-linear approach. Finally the effects of noise are also investigated below the instability threshold. PMID:27669998

  1. 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.

  2. 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.

  3. Control of lymphocyte shape and the chemotactic response by the GTP exchange factor Vav.

    PubMed

    Vicente-Manzanares, Miguel; Cruz-Adalia, Aranzazu; Martín-Cófreces, Noa B; Cabrero, José R; Dosil, Mercedes; Alvarado-Sánchez, Brenda; Bustelo, Xosé R; Sánchez-Madrid, Francisco

    2005-04-15

    Rho GTPases control many facets of cell polarity and migration; namely, the reorganization of the cellular cytoskeleton to extracellular stimuli. Rho GTPases are activated by GTP exchange factors (GEFs), which induce guanosine diphosphate (GDP) release and the stabilization of the nucleotide-free state. Thus, the role of GEFs in the regulation of the cellular response to extracellular cues during cell migration is a critical step of this process. In this report, we have analyzed the activation and subcellular localization of the hematopoietic GEF Vav in human peripheral blood lymphocytes stimulated with the chemokine stromal cell-derived factor-1 (SDF-1alpha). We show a robust activation of Vav and its redistribution to motility-associated subcellular structures, and we provide biochemical evidence of the recruitment of Vav to the membrane of SDF-1alpha-activated human lymphocytes, where it transiently interacts with the SDF-1alpha receptor CXCR4. Overexpression of a dominant negative form of Vav abolished lymphocyte polarization, actin polymerization, and migration. SDF-1alpha-mediated cell polarization and migration also were impaired by overexpression of an active, oncogenic Vav, although the mechanism appears to be different. Together, our data postulate a pivotal role for Vav in the transmission of the migratory signal through the chemokine receptor CXCR4.

  4. Single-cell E. coli response to an instantaneously applied chemotactic signal.

    PubMed

    Sagawa, Takashi; Kikuchi, Yu; Inoue, Yuichi; Takahashi, Hiroto; Muraoka, Takahiro; Kinbara, Kazushi; Ishijima, Akihiko; Fukuoka, Hajime

    2014-08-05

    In response to an attractant or repellant, an Escherichia coli cell controls the rotational direction of its flagellar motor by a chemotaxis system. When an E. coli cell senses an attractant, a reduction in the intracellular concentration of a chemotaxis protein, phosphorylated CheY (CheY-P), induces counterclockwise (CCW) rotation of the flagellar motor, and this cellular response is thought to occur in several hundred milliseconds. Here, to measure the signaling process occurring inside a single E. coli cell, including the recognition of an attractant by a receptor cluster, the inactivation of histidine kinase CheA, and the diffusion of CheY and CheY-P molecules, we applied a serine stimulus by instantaneous photorelease from a caged compound and examined the cellular response at a temporal resolution of several hundred microseconds. We quantified the clockwise (CW) and CCW durations immediately after the photorelease of serine as the response time and the duration of the response, respectively. The results showed that the response time depended on the distance between the receptor and motor, indicating that the decreased CheY-P concentration induced by serine propagates through the cytoplasm from the receptor-kinase cluster toward the motor with a timing that is explained by the diffusion of CheY and CheY-P molecules. The response time included 240 ms for enzymatic reactions in addition to the time required for diffusion of the signaling molecule. The measured response time and duration of the response also revealed that the E. coli cell senses a similar serine concentration regardless of whether the serine concentration is increasing or decreasing. These detailed quantitative findings increase our understanding of the signal transduction process that occurs inside cells during bacterial chemotaxis.

  5. 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.

  6. Structure of bacterial cytoplasmic chemoreceptor arrays and implications for chemotactic signaling

    PubMed Central

    Briegel, Ariane; Ladinsky, Mark S; Oikonomou, Catherine; Jones, Christopher W; Harris, Michael J; Fowler, Daniel J; Chang, Yi-Wei; Thompson, Lynmarie K; Armitage, Judith P; Jensen, Grant J

    2014-01-01

    Most motile bacteria sense and respond to their environment through a transmembrane chemoreceptor array whose structure and function have been well-studied, but many species also contain an additional cluster of chemoreceptors in their cytoplasm. Although the cytoplasmic cluster is essential for normal chemotaxis in some organisms, its structure and function remain unknown. Here we use electron cryotomography to image the cytoplasmic chemoreceptor cluster in Rhodobacter sphaeroides and Vibrio cholerae. We show that just like transmembrane arrays, cytoplasmic clusters contain trimers-of-receptor-dimers organized in 12-nm hexagonal arrays. In contrast to transmembrane arrays, however, cytoplasmic clusters comprise two CheA/CheW baseplates sandwiching two opposed receptor arrays. We further show that cytoplasmic fragments of normally transmembrane E. coli chemoreceptors form similar sandwiched structures in the presence of molecular crowding agents. Together these results suggest that the 12-nm hexagonal architecture is fundamentally important and that sandwiching and crowding can replace the stabilizing effect of the membrane. DOI: http://dx.doi.org/10.7554/eLife.02151.001 PMID:24668172

  7. 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...

  8. Enhancement of Swimming Speed Leads to a More-Efficient Chemotactic Response to Repellent

    PubMed Central

    Uday Bhaskar, R. V. S.; Jesudasan, Rajesh E.; Venkatesh, K. V.

    2015-01-01

    Negative chemotaxis refers to the motion of microorganisms away from regions with high concentrations of chemorepellents. In this study, we set controlled gradients of NiCl2, a chemorepellent, in microchannels to quantify the motion of Escherichia coli over a broad range of concentrations. The experimental technique measured the motion of the bacteria in space and time and further related the motion to the local concentration profile of the repellent. Results show that the swimming speed of bacteria increases with an increasing concentration of repellent, which in turn enhances the drift velocity. The contribution of the increased swimming speed to the total drift velocity was in the range of 20 to 40%, with the remaining contribution coming from the modulation of the tumble frequency. A simple model that incorporates receptor dynamics, including adaptation, intracellular signaling, and swimming speed variation, was able to qualitatively capture the observed trend in drift velocity. PMID:26655753

  9. Chemotactic properties and absence of the formyl peptide receptor in ferret (Mustela putorius furo) neutrophils.

    PubMed

    Nakata, Makoto; Otsubo, Kouji; Kikuchi, Tomoko; Itou, Takuya; Sakai, Takeo

    2010-02-01

    This study describes a chemotaxis assay of ferret polymorphonuclear cells (PMNs). The optimal conditions for this chemotaxis assay were investigated for three chemoattractants: zymosan activated serum (ZAS), recombinant human interleukin-8 (rhIL-8) and N-formyl-Met-Leu- Phe (fMLF). In this study, ferret polymorphonuclear cells (PMNs) reacted to ZAS and rhIL-8, but not fMLF. The optimal concentration of ZAS and rhIL-8 were 5% and 100 ng/ml, respectively. The optimal incubation time of each reagent was 60 min. Due to the lack of response shown from fMLF, the existence of formyl peptide receptors (FPR) on ferret PMNs was investigated by evaluating FPR binding using flow cytometry. The receptor was not detected, implying that ferret neutrophils may lack FPR. This study confirms the fundamental experimental conditions for ferret PMNs chemotaxis and elucidates new findings concerning FPR in ferret neutrophils.

  10. Modeling the chemotactic response of Escherichia coli to time-varying stimuli

    PubMed Central

    Tu, Yuhai; Shimizu, Thomas S.; Berg, Howard C.

    2008-01-01

    In their natural environment, cells need to extract useful information from complex temporal signals that vary over a wide range of intensities and time scales. Here, we study how such signals are processed by Escherichia coli during chemotaxis by developing a general theoretical model based on receptor adaptation and receptor–receptor cooperativity. Measured responses to various monotonic, oscillatory, and impulsive stimuli are all explained consistently by the underlying adaptation kinetics within this model. For exponential ramp signals, an analytical solution is discovered that reveals a remarkable connection between the dependence of kinase activity on the exponential ramp rate and the receptor methylation rate function. For exponentiated sine-wave signals, spectral analysis shows that the chemotaxis pathway acts as a lowpass filter for the derivative of the signal with the cutoff frequency determined by an intrinsic adaptation time scale. For large step stimuli, we find that the recovery time is determined by the constant maximum methylation rate, which provides a natural explanation for the observed recovery time additivity. Our model provides a quantitative system-level description of the chemotaxis signaling pathway and can be used to predict E. coli chemotaxis responses to arbitrary temporal signals. This model of the receptor system reveals the molecular origin of Weber's law in bacterial chemotaxis. We further identify additional constraints required to account for the related observation that the output of this pathway is constant under exponential ramp stimuli, a feature that we call “logarithmic tracking.” PMID:18812513

  11. Onset of nonlinearity in a stochastic model for auto-chemotactic advancing epithelia

    NASA Astrophysics Data System (ADS)

    Ben Amar, Martine; Bianca, Carlo

    2016-09-01

    We investigate the role of auto-chemotaxis in the growth and motility of an epithelium advancing on a solid substrate. In this process, cells create their own chemoattractant allowing communications among neighbours, thus leading to a signaling pathway. As known, chemotaxis provokes the onset of cellular density gradients and spatial inhomogeneities mostly at the front, a phenomenon able to predict some features revealed in in vitro experiments. A continuous model is proposed where the coupling between the cellular proliferation, the friction on the substrate and chemotaxis is investigated. According to our results, the friction and proliferation stabilize the front whereas auto-chemotaxis is a factor of destabilization. This antagonist role induces a fingering pattern with a selected wavenumber k0. However, in the planar front case, the translational invariance of the experimental set-up gives also a mode at k = 0 and the coupling between these two modes in the nonlinear regime is responsible for the onset of a Hopf-bifurcation. The time-dependent oscillations of patterns observed experimentally can be predicted simply in this continuous non-linear approach. Finally the effects of noise are also investigated below the instability threshold.

  12. 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.

  13. 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

  14. 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

  15. The ultrastructure of Commation gen. nov. (Stramenopiles incertae sedis), a genus of heterotrophic nanoplanktonic flagellates from antarctic waters.

    PubMed

    Thomsen, H A; Larsen, J

    1993-11-12

    Commation gen. nov. is a genus of planktonic, unicellular protists characterized by a circular to oval (sometimes flattened) cell body and a proboscis. Cells move predominantly by gliding. The mitochondria are tubulocristate and the two flagellar basal bodies are furnished with microtubular roots as well as a rhizoplast. The single emerging flagellum, which is rarely observed, apparently carries tripartite hairs. These features suggest that Commation should be listed among the genera and groups of organisms assembled in the informal group stramenopiles. Two species, C. eposianum sp. nov. (previously referred to as the "comma-shaped amoeba") and C. cryoporinum sp. nov., are described from Antarctic waters. The species are distinguished by differences in, e.g., the morphology of the proboscis, the complexity and details of the cytoskeleton, and the number of types of extrusomes present. Commation spp. appear to be ubiquitous in Antarctic waters at cell abundancies typically ranging from 10(3)-10(4) cells per litre.

  16. 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

    2014-04-05

    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.

  17. A possible role for short introns in the acquisition of stroma-targeting peptides in the flagellate Euglena gracilis.

    PubMed

    Vesteg, Matej; Vacula, Rostislav; Steiner, Jürgen M; Mateásiková, Bianka; Löffelhardt, Wolfgang; Brejová, Brona; Krajcovic, Juraj

    2010-08-01

    The chloroplasts of Euglena gracilis bounded by three membranes arose via secondary endosymbiosis of a green alga in a heterotrophic euglenozoan host. Many genes were transferred from symbiont to the host nucleus. A subset of Euglena nuclear genes of predominately symbiont, but also host, or other origin have obtained complex presequences required for chloroplast targeting. This study has revealed the presence of short introns (41-93 bp) either in the second half of presequence-encoding regions or shortly downstream of them in nine nucleus-encoded E. gracilis genes for chloroplast proteins (Eno29, GapA, PetA, PetF, PetJ, PsaF, PsbM, PsbO, and PsbW). In addition, the E. gracilis Pbgd gene contains two introns in the second half of presequence-encoding region and one at the border of presequence-mature peptide-encoding region. Ten of 12 introns present within presequence-encoding regions or shortly downstream of them identified in this study have typical eukaryotic GT/AG borders, are T-rich, 45-50 bp long, and pairwise sequence identities range from 27 to 61%. Thus single recombination events might have been mediated via these cis-spliced introns. A double crossing over between these cis-spliced introns and trans-spliced introns present in 5'-UTRs of Euglena nuclear genes is also likely to have occurred. Thus introns and exon-shuffling could have had an important role in the acquisition of chloroplast targeting signals in E. gracilis. The results are consistent with a late origin of photosynthetic euglenids.

  18. Tetraflagellochloris mauritanica gen. et sp. nov. (Chlorophyceae), a New Flagellated Alga from the Mauritanian Desert: Morphology, Ultrastructure, and Phylogenetic Framing.

    PubMed

    Barsanti, Laura; Frassanito, Anna Maria; Passarelli, Vincenzo; Evangelista, Valtere; Etebari, Maryam; Paccagnini, Eugenio; Lupetti, Pietro; Lenzi, Paola; Verni, Franco; Gualtieri, Paolo

    2013-02-01

    Morphological, ultrastructural, and molecular-sequence data were used to assess the phylogenetic position of a tetraflagellate green alga isolated from soil samples of a saline dry basin near F'derick, Mauritania. This alga can grow as individual cells or form non-coenobial colonies of up to 12 individuals. It has a parietal chloroplast with an embedded pyrenoid covered by a starch sheath and traversed by single parallel thylakoids, and an eyespot located in a parietal position opposite to the flagellar insertion. Lipid vacuoles are present in the cytoplasm. Microspectroscopy indicated the presence of chlorophylls a and b, with lutein as the major carotenoid in the chloroplast, while the eyespot spectrum has a shape typical of green-algal eyespots. The cell has four flagella, two of them long and two considerably shorter. Sequence data from the 18S rRNA gene and ITS2 were obtained and compared with published sequences for green algae. Results from morphological and ultrastructural examinations and sequence analysis support the placement of this alga in the Chlorophyceae, as Tetraflagellochloris mauritanica L. Barsanti et A. Barsanti, gen. et sp. nov.

  19. 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

  20. Immunochemical properties of Proteus penneri lipopolysaccharides--one of the major Proteus sp. virulence factors.

    PubMed

    Palusiak, Agata

    2013-10-18

    Proteus penneri, like the other seven species from the genus, are Gram-negative, peritrichously flagellated rods capable of swarming growth on humid solid media. These bacteria are human opportunistic pathogens involved in many infections but they mainly affect the urinary tract of hospitalized, long-term catheterized patients. P. penneri rods produce a lot of virulence factors, among which the lipopolysaccharide seems to be the most interesting due to its structural and serological diversity. From the three LPS regions of P. penneri strains only the core region and O-specific polysaccharide (OPS) were structurally and serologically examined. P. penneri LPS core region is characterized by a common inner part representing the III glycoform and a diverse distal part (12 different structures). The P. penneri O-antigens contain sugar and non-sugar compounds and some of them rarely occur in nature. In both P. penneri LPS regions putative epitopes have been pointed out. Serospecificity of OPS allowed classifying many P. penneri isolates to different Proteus sp. O-serogroups, among which 12 contain P. penneri strains only.

  1. Quorum polarity and the dynamics of the zooming bionematic phase

    NASA Astrophysics Data System (ADS)

    Kessler, John O.

    2005-03-01

    Many species of bacteria are peritrichously flagellated, i.e. the long, helical, rapidly rotating flagella that propel them emerge out of motors that appear randomly distributed over the body of the bacterial cell. The organism considered here is Bacillus subtilis. The cell body is a rod approximately 4 μm long, 0.7μm in diameter; flagella are 3 or 4 times longer than the body. Swimming cells are pushed by the flagella, bundled into a braid of rotating helices. When the bacteria self concentrate into an approximately close-packed assemblage, rapidly moving (zooming) domains of aligned bacterial rods continually form and break apart. PIV measurements show that correlation times are seconds, lengths are hundreds of micrometers, transport of passive tracers is superdiffusive.Below a threshold concentration there is no collective dynamic. A theory of this zooming bionematic phase will be presented, together with measurements and video sequences. The theory considers hydrodynamic cell-cell and collective interactions, the collectively generated flow of the suspending water relative to the cells, and the dynamics of helix bundle flipping, yielding quorum polarity within a given zooming domain. Quorum sensing of signalling molecules and molecular transport generally are pertinent microbiological applications.

  2. BASE COMPOSITION OF THE DEOXYRIBONUCLEIC ACID OF SULFATE-REDUCING BACTERIA.

    PubMed

    SIGAL, N; SENEZ, J C; LEGALL, J; SEBALD, M

    1963-06-01

    Sigal, Nicole (Laboratoire de Chimie Bactérienne du CNRS, Marseille, France), Jacques C. Senez, Jean Le Gall, and Madeleine Sebald. Base composition of the deoxyribonucleic acid of sulfate-reducing bacteria. J. Bacteriol. 85:1315-1318. 1963-The deoxyribonucleic acid constitution of several strains of sulfate-reducing bacteria has been analytically determined. The results of these studies show that this group of microorganisms includes at least four subgroups characterized by significantly different values of the adenine plus thymine to guanine plus cytosine ratio. The nonsporulated forms with polar flagellation, containing both cytochrome c(3) and desulfoviridin, are divided into two subgroups. One includes the fresh-water, nonhalophilic strains with base ratio from 0.54 to 0.59, and the other includes the halophilic or halotolerant strains with base ratio from 0.74 to 0.77. The sporulated, peritrichous strains without cytochrome and desulfoviridin ("nigrificans" and "orientis") are distinct from the above two types and differ from each other, having base ratios of 1.20 and 1.43, respectively.

  3. 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

  4. Extracellular and intracellular factors regulating the migration direction of a chemotactic cell in traveling-wave chemotaxis

    NASA Astrophysics Data System (ADS)

    Ishiwata, R.; Iwasa, M.

    2015-04-01

    This report presents a simple model that describes the motion of a single Dictyostelium discoideum cell exposed to a traveling wave of cyclic adenosine monophosphate (cAMP). The model incorporates two types of responses to stimulation by cAMP: the changes in the polarity and motility of the cell. The periodic change in motility is assumed to be induced by periodic cAMP stimulation on the basis of previous experimental studies. Consequently, the net migration of the cell occurs in a particular direction with respect to wave propagation, which explains the migration of D. discoideum cells in aggregation. The wave period and the difference between the two response times are important parameters that determine the direction of migration. The theoretical prediction compared with experiments presented in another study. The transition from the single-cell state of the population of D. discoideum cells to the aggregation state is understood to be a specific example of spontaneous breakage of symmetry in biology.

  5. Microfluidic study of the chemotactic response of Escherichia coli to amino acids, signaling molecules and secondary metabolites

    PubMed Central

    Nagy, Krisztina; Sipos, Orsolya; Valkai, Sándor; Gombai, Éva; Hodula, Orsolya; Kerényi, Ádám; Ormos, Pál; Galajda, Péter

    2015-01-01

    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

  6. 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...

  7. Subcutaneous Transplantation of Neural Precursor Cells in Experimental Autoimmune Encephalomyelitis Reduces Chemotactic Signals in the Central Nervous System

    PubMed Central

    Ravanidis, Stylianos; Poulatsidou, Kyriaki Nepheli; Lagoudaki, Roza; Touloumi, Olga; Polyzoidou, Elena; Lourbopoulos, Athanasios; Nousiopoulou, Evangelia; Theotokis, Paschalis; Kesidou, Evangelia; Tsalikakis, Dimitrios; Karacostas, Dimitrios; Grigoriou, Maria; Chlichlia, Katerina

    2015-01-01

    Neural precursor cell (NPC) transplantation has been proposed as a therapy for multiple sclerosis (MS) and other degenerative disorders of the central nervous system (CNS). NPCs are suggested to exert immune modulation when they are transplanted in the animal model of MS, experimental autoimmune encephalomyelitis (EAE). Herein, we explore whether the effect of NPC transplantation on the clinical course and the pathological features of EAE is combined with the modulation of chemokines levels expressed in the inflamed CNS. NPCs were isolated from brains of neonatal C57/Bl6 mice and were subcutaneously administered in female mice with myelin oligodendrocyte glycoprotein (MOG)-induced EAE. Clinical signs of the disease and transcript analysis of the CNS in the acute phase were performed. In addition, the presence of inflammatory components in the spinal cord was evaluated and ex vivo proliferation of lymphocytes was measured. NPC recipients exhibited ameliorated clinical outcome and less pronounced pathological features in their spinal cord. Downregulation of chemokine mRNA levels throughout the CNS was correlated with diminished Mac-3-, CD3-, and CD4-positive cells and reduced expression levels of antigen-presenting molecules in the spinal cord. Moreover, NPC transplantation resulted in lymphocyte-related, although not splenocyte-related, peripheral immunosuppression. We conclude that NPCs ameliorated EAE potentially by modulating the levels of chemokines expressed in the inflamed CNS, thus resulting in the impaired recruitment of immune cells. These findings further contribute to the better understanding of NPCs’ immunomodulatory properties in neuroinflammatory disorders, and may lead to faster translation into potential clinical use. Significance Endogenous neural precursor cells of the central nervous system are able to migrate and differentiate toward mature cells to repair an injury. There is increasing evidence that autologous transplantation of these cells in experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis, may have a beneficial effect on the disease process. Several mechanisms have been proposed—among them, the potentiation of endogenous precursor cell differentiation of the central nervous system and the modulation of demyelinating and neurodegenerative immune-mediated processes. This article provides evidence of interference in immune signaling within the central nervous system as a potential mechanism underlying the immunomodulatory properties of transplanted neural precursor cells. PMID:26511651

  8. 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.

  9. Boundedness for a 3D chemotaxis-Stokes system with porous medium diffusion and tensor-valued chemotactic sensitivity

    NASA Astrophysics Data System (ADS)

    Wang, Yilong; Li, Xie

    2017-04-01

    This paper deals with the following chemotaxis-Stokes system n_t+u\\cdot nabla n=Δ n^m-nabla \\cdot (nS(x,n,c)\\cdot nabla c), &{}quad xin Ω , t>0, c_t+u\\cdot nabla c=Δ c-nf(c),&{}quad xin Ω , t>0, u_t=Δ u+nabla P+nnabla φ ,&quad xin Ω , t>0,\\ nabla \\cdot u=0,&{}quad xin Ω , t>0. under no-flux boundary conditions in a bounded domain Ω subset R3 with smooth boundary, where m≥ 1, φ in W^{1,∞}(Ω ), f and S are given functions with values in [0, ∞) and R^{3× 3}, respectively. Here S satisfies |S(x,n,c)|7/6, which insures the global existence of bounded weak solution. Our result covers completely and improves the recent result by Wang and Cao (Discrete Contin Dyn Syst Ser B 20:3235-3254, 2015) which asserts, just in the case m=1, the global existence of solutions, but without boundedness, and that by Winkler (Calc Var Partial Differ Equ 54:3789-3828, 2015) which only involves the case of α =0 and requires the convexity of the domain.

  10. From the Cover: Bacterial flagellum as a propeller and as a rudder for efficient chemotaxis.

    PubMed

    Xie, Li; Altindal, Tuba; Chattopadhyay, Suddhashil; Wu, Xiao-Lun

    2011-02-08

    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 t(f) and backward t(b) swimming times are uncorrelated. Interestingly, although t(f) and t(b) are not distributed in a Poissonian fashion, their difference Δt = |t(f) - t(b)| is. Near a point source of attractant, on the other hand, t(f) and t(b) 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.

  11. 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.

  12. 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.

  13. The stem cell system in demosponges: suggested involvement of two types of cells: archeocytes (active stem cells) and choanocytes (food-entrapping flagellated cells).

    PubMed

    Funayama, Noriko

    2013-03-01

    Major questions about stem cell systems include what type(s) of stem cells are involved (unipotent/totipotent/pluripotent/multipotent stem cells) and how the self-renewal and differentiation of stem cells are regulated. Sponges, the sister group of all other animals and probably the earliest branching multicellular lineage of extant animals, are thought to possess totipotent stem cells. This review introduces what is known about the stem cells in sponges based on histological studies and also on recent molecular biological studies that have started to reveal the molecular and cellular mechanisms of the stem cell system in sponges (mainly in demosponges). The currently proposed model of the stem cell system in demosponges is described, and the possible applicability of this model to other classes of sponges is discussed. Finally, a possible scenario of the evolution of stem cells, including how migrating stem cells arose in the urmetazoan (the last common ancestor of metazoans) and the evolutionary origin of germ line cells in the urbilaterian (the last common ancestor of bilaterians), are discussed.

  14. 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

  15. 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

  16. Activation of NLRC4 by flagellated bacteria triggers caspase-1-dependent and -independent responses to restrict Legionella pneumophila replication in macrophages and in vivo.

    PubMed

    Pereira, Marcelo S F; Morgantetti, Giuliano F; Massis, Liliana M; Horta, Catarina V; Hori, Juliana I; Zamboni, Dario S

    2011-12-15

    Although NLRC4/IPAF activation by flagellin has been extensively investigated, the downstream signaling pathways and the mechanisms responsible for infection clearance remain unclear. In this study, we used mice deficient for the inflammasome components in addition to wild-type (WT) Legionella pneumophila or bacteria deficient for flagellin (flaA) or motility (fliI) to assess the pathways responsible for NLRC4-dependent growth restriction in vivo and ex vivo. By comparing infections with WT L. pneumophila, fliI, and flaA, we found that flagellin and motility are important for the colonization of the protozoan host Acanthamoeba castellanii. However, in macrophages and mammalian lungs, flagellin expression abrogated bacterial replication. The flagellin-mediated growth restriction was dependent on NLRC4, and although it was recently demonstrated that NLRC4 is able to recognize bacteria independent of flagellin, we found that the NLRC4-dependent restriction of L. pneumophila multiplication was fully dependent on flagellin. By examining infected caspase-1(-/-) mice and macrophages with flaA, fliI, and WT L. pneumophila, we could detect greater replication of flaA, which suggests that caspase-1 only partially accounted for flagellin-dependent growth restriction. Conversely, WT L. pneumophila multiplied better in macrophages and mice deficient for NLRC4 compared with that in macrophages and mice deficient for caspase-1, supporting the existence of a novel caspase-1-independent response downstream of NLRC4. This response operated early after macrophage infection and accounted for the restriction of bacterial replication within bacteria-containing vacuoles. Collectively, our data indicate that flagellin is required for NLRC4-dependent responses to L. pneumophila and that NLRC4 triggers caspase-1-dependent and -independent responses for bacterial growth restriction in macrophages and in vivo.

  17. Multiple origins of Heliozoa from flagellate ancestors: New cryptist subphylum Corbihelia, superclass Corbistoma, and monophyly of Haptista, Cryptista, Hacrobia and Chromista.

    PubMed

    Cavalier-Smith, Thomas; Chao, Ema E; Lewis, Rhodri

    2015-12-01

    Heliozoan protists have radiating cell projections (axopodia) supported by microtubular axonemes nucleated by the centrosome and bearing granule-like extrusomes for catching prey. To clarify previously confused heliozoan phylogeny we sequenced partial transcriptomes of two tiny naked heliozoa, the endohelean Microheliella maris and centrohelid Oxnerella marina, and the cercozoan pseudoheliozoan Minimassisteria diva. Phylogenetic analysis of 187 genes confirms that all are chromists; but centrohelids (microtubules arranged as hexagons and triangles) are not sisters to Endohelea having axonemes in transnuclear cytoplasmic channels (triangular or square microtubular arrays). Centrohelids are strongly sister to haptophytes (together phylum Haptista); we explain the common origins of their axopodia and haptonema. Microheliella is sister to new superclass Corbistoma (zooflagellate Telonemea and Picomonadea, with asymmetric microfilamentous pharyngeal basket), showing that these axopodial protists evolved independently from zooflagellate ancestors. We group Corbistoma and Endohelea as new cryptist subphylum Corbihelia with dense fibrillar interorganellar connections; endohelean axopodia and Telonema cortex are ultrastructurally related. Differently sampled trees clarify why corticate multigene eukaryote phylogeny is problematic: long-branch artefacts probably distort deep multigene phylogeny of corticates (Plantae, Chromista); basal radiations may be contradictorily reconstructed because of their extreme closeness and the Bayesian star-tree paradox. Haptista and Hacrobia are holophyletic, and Chromista probably are.

  18. Caspase-1 but Not Caspase-11 Is Required for NLRC4-Mediated Pyroptosis and Restriction of Infection by Flagellated Legionella Species in Mouse Macrophages and In Vivo.

    PubMed

    Cerqueira, Daiane M; Pereira, Marcelo S F; Silva, Alexandre L N; Cunha, Larissa D; Zamboni, Dario S

    2015-09-01

    Gram-negative bacteria from the Legionella genus are intracellular pathogens that cause a severe form of pneumonia called Legionnaires' disease. The bacteria replicate intracellularly in macrophages, and the restriction of bacterial replication by these cells is critical for host resistance. The activation of the NAIP5/NLRC4 inflammasome, which is readily triggered in response to bacterial flagellin, is essential for the restriction of bacterial replication in murine macrophages. Once activated, this inflammasome induces pore formation and pyroptosis and facilitates the restriction of bacterial replication in macrophages. Because investigations related to the NLRC4-mediated restriction of Legionella replication were performed using mice double deficient for caspase-1 and caspase-11, we assessed the participation of caspase-1 and caspase-11 in the functions of the NLRC4 inflammasome and the restriction of Legionella replication in macrophages and in vivo. By using several species of Legionella and mice singly deficient for caspase-1 or caspase-11, we demonstrated that caspase-1 but not caspase-11 was required for pore formation, pyroptosis, and restriction of Legionella replication in macrophages and in vivo. By generating F1 mice in a mixed 129 × C57BL/6 background deficient (129 × Casp-11(-/-) ) or sufficient (129 × C57BL/6) for caspase-11 expression, we found that caspase-11 was dispensable for the restriction of Legionella pneumophila replication in macrophages and in vivo. Thus, although caspase-11 participates in flagellin-independent noncanonical activation of the NLRP3 inflammasome, it is dispensable for the activities of the NLRC4 inflammasome. In contrast, functional caspase-1 is necessary and sufficient to trigger flagellin/NLRC4-mediated restriction of Legionella spp. infection in macrophages and in vivo.

  19. An investigation of the fine structure, cell surface carbohydrates, and appeal of the diatom Extubocellulus sp. as prey for small flagellates.

    PubMed

    Martin-Cereceda, M; Williams, R; Guinea, A; Novarino, G

    2007-01-01

    The fine structure and surface exopolymers of a coastal planktonic nanodiatom of the sparsely reported genus Extubocellulus were studied respectively by scanning electron microscopy and confocal microscopy in conjunction with fluorescent lectins. Monitoring the suitability of the species as prey food for other protists was also investigated by video microscopy coupled with digital film. Cells are rectangular in girdle view, with a pervalvar axis longer than the apical axis. Valves are almost circular with a diameter of 2.8 to 3.6 microm. The valve face bears randomly distributed areolae (ca. 50 in 10 microm), which may be either open or occluded. Two small raised ocelluli occur at the apices, with a rim devoid of perforations and about 6-7 porelli. Glucose and N-acetyl-glucosamine moieties present on the surface of the live diatom were labelled with fluorescent lectins, and a differential pattern of distribution for both carbohydrates was observed. The potential role of fluorescent lectins as cellular probes of taxonomic value in small diatoms is compared with that of nucleotide and antibody probes. We provide the first illustrative evidence of the presence of Extubocellulus sp. in the cytoplasm of the nanoflagellate Goniomonas amphinema and of the egestion of diatom frustules. Results obtained are discussed in the light of the present knowledge of the role of carbohydrate-protein interactions in phagocytosis of prey by free-living protozoa.

  20. An integrative approach to phylogeny reveals patterns of environmental distribution and novel evolutionary relationships in a major group of ciliates.

    PubMed

    Sun, Ping; Clamp, John; Xu, Dapeng; Huang, Bangqin; Shin, Mann Kyoon

    2016-02-16

    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.

  1. 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

  2. Chemotactic and inflammatory responses in the liver and brain are associated with pathogenesis of Rift Valley fever virus infection in the mouse.

    PubMed

    Gray, Kimberly K; Worthy, Melissa N; Juelich, Terry L; Agar, Stacy L; Poussard, Allison; Ragland, Dan; Freiberg, Alexander N; Holbrook, Michael R

    2012-01-01

    Rift Valley fever virus (RVFV) is a major human and animal pathogen associated with severe disease including hemorrhagic fever or encephalitis. RVFV is endemic to parts of Africa and the Arabian Peninsula, but there is significant concern regarding its introduction into non-endemic regions and the potentially devastating effect to livestock populations with concurrent infections of humans. To date, there is little detailed data directly comparing the host response to infection with wild-type or vaccine strains of RVFV and correlation with viral pathogenesis. Here we characterized clinical and systemic immune responses to infection with wild-type strain ZH501 or IND vaccine strain MP-12 in the C57BL/6 mouse. Animals infected with live-attenuated MP-12 survived productive viral infection with little evidence of clinical disease and minimal cytokine response in evaluated tissues. In contrast, ZH501 infection was lethal, caused depletion of lymphocytes and platelets and elicited a strong, systemic cytokine response which correlated with high virus titers and significant tissue pathology. Lymphopenia and platelet depletion were indicators of disease onset with indications of lymphocyte recovery correlating with increases in G-CSF production. RVFV is hepatotropic and in these studies significant clinical and histological data supported these findings; however, significant evidence of a pro-inflammatory response in the liver was not apparent. Rather, viral infection resulted in a chemokine response indicating infiltration of immunoreactive cells, such as neutrophils, which was supported by histological data. In brains of ZH501 infected mice, a significant chemokine and pro-inflammatory cytokine response was evident, but with little pathology indicating meningoencephalitis. These data suggest that RVFV pathogenesis in mice is associated with a loss of liver function due to liver necrosis and hepatitis yet the long-term course of disease for those that might survive the initial hepatitis is neurologic in nature which is supported by observations of human disease and the BALB/c mouse model.

  3. Chemotactic and Inflammatory Responses in the Liver and Brain Are Associated with Pathogenesis of Rift Valley Fever Virus Infection in the Mouse

    PubMed Central

    Juelich, Terry L.; Agar, Stacy L.; Poussard, Allison; Ragland, Dan; Freiberg, Alexander N.; Holbrook, Michael R.

    2012-01-01

    Rift Valley fever virus (RVFV) is a major human and animal pathogen associated with severe disease including hemorrhagic fever or encephalitis. RVFV is endemic to parts of Africa and the Arabian Peninsula, but there is significant concern regarding its introduction into non-endemic regions and the potentially devastating effect to livestock populations with concurrent infections of humans. To date, there is little detailed data directly comparing the host response to infection with wild-type or vaccine strains of RVFV and correlation with viral pathogenesis. Here we characterized clinical and systemic immune responses to infection with wild-type strain ZH501 or IND vaccine strain MP-12 in the C57BL/6 mouse. Animals infected with live-attenuated MP-12 survived productive viral infection with little evidence of clinical disease and minimal cytokine response in evaluated tissues. In contrast, ZH501 infection was lethal, caused depletion of lymphocytes and platelets and elicited a strong, systemic cytokine response which correlated with high virus titers and significant tissue pathology. Lymphopenia and platelet depletion were indicators of disease onset with indications of lymphocyte recovery correlating with increases in G-CSF production. RVFV is hepatotropic and in these studies significant clinical and histological data supported these findings; however, significant evidence of a pro-inflammatory response in the liver was not apparent. Rather, viral infection resulted in a chemokine response indicating infiltration of immunoreactive cells, such as neutrophils, which was supported by histological data. In brains of ZH501 infected mice, a significant chemokine and pro-inflammatory cytokine response was evident, but with little pathology indicating meningoencephalitis. These data suggest that RVFV pathogenesis in mice is associated with a loss of liver function due to liver necrosis and hepatitis yet the long-term course of disease for those that might survive the initial hepatitis is neurologic in nature which is supported by observations of human disease and the BALB/c mouse model. PMID:22389738

  4. Kisspeptin-10-induced signaling of GPR54 negatively regulates chemotactic responses mediated by CXCR4: a potential mechanism for the metastasis suppressor activity of kisspeptins.

    PubMed

    Navenot, Jean-Marc; Wang, Zixuan; Chopin, Michael; Fujii, Nobutaka; Peiper, Stephen C

    2005-11-15

    The product of the KiSS-1 gene is absent or expressed at low level in metastatic melanoma and breast cancer compared with their nonmetastatic counterparts. A polypeptide derived from the KiSS-1 product, designated kisspeptin-10 (Kp-10), activates a receptor coupled to Galphaq subunits (GPR54 or KiSS-1R). To study the mechanism by which Kp-10 antagonizes metastatic spread, the effect on CXCR4-mediated signaling, which has been shown to direct organ-specific migration of tumor cells, was determined. Kp-10 blocked chemotaxis of tumor cells expressing CXCR4 in response to low and high concentrations of SDF-1/CXCL12 and inhibited mobilization of calcium ions induced by this ligand. Pretreatment with Kp-10 did not induce down-modulation of cell surface CXCR4 expression, reduce affinity for SDF-1/CXCL12, or alter Galphai subunit activation stimulated by this ligand. Although Kp-10 stimulated prolonged phosphorylation of extracellular signal-regulated kinase 1/2, it inhibited the phosphorylation of Akt induced by SDF-1. The ability of Kp-10 to inhibit signaling and chemotaxis induced by SDF-1 indicates that activation of GPR54 signaling may negatively regulate the role of CXCR4 in programming tumor metastasis.

  5. Negative regulatory roles of ORMDL3 in the FcεRI-triggered expression of proinflammatory mediators and chemotactic response in murine mast cells.

    PubMed

    Bugajev, Viktor; Halova, Ivana; Draberova, Lubica; Bambouskova, Monika; Potuckova, Lucie; Draberova, Helena; Paulenda, Tomas; Junyent, Sergi; Draber, Petr

    2016-03-01

    Single-nucleotide polymorphism studies have linked the chromosome 17q12-q21 region, where the human orosomucoid-like (ORMDL)3 gene is localized, to the risk of asthma and several other inflammatory diseases. Although mast cells are involved in the development of these diseases, the contribution of ORMDL3 to the mast cell physiology is unknown. In this study, we examined the role of ORMDL3 in antigen-induced activation of murine mast cells with reduced or enhanced ORMDL3 expression. Our data show that in antigen-activated mast cells, reduced expression of the ORMDL3 protein had no effect on degranulation and calcium response, but significantly enhanced phosphorylation of AKT kinase at Ser 473 followed by enhanced phosphorylation and degradation of IκBα and translocation of the NF-κB p65 subunit into the nucleus. These events were associated with an increased expression of proinflammatory cytokines (TNF-α, IL-6, and IL-13), chemokines (CCL3 and CCL4), and cyclooxygenase-2 dependent synthesis of prostaglandin D2. Antigen-mediated chemotaxis was also enhanced in ORMDL3-deficient cells, whereas spreading on fibronectin was decreased. On the other hand, increased expression of ORMDL3 had no significant effect on the studied signaling events, except for reduced antigen-mediated chemotaxis. These data were corroborated by increased IgE-antigen-dependent passive cutaneous anaphylaxis in mice with locally silenced ORMDL3 using short interfering RNAs. Our data also show that antigen triggers suppression of ORMDL3 expression in the mast cells. In summary, we provide evidence that downregulation of ORMDL3 expression in mast cells enhances AKT and NF-κB-directed signaling pathways and chemotaxis and contributes to the development of mast cell-mediated local inflammation in vivo.

  6. cAMP-induced actin cytoskeleton remodelling inhibits MKL1-dependent expression of the chemotactic and pro-proliferative factor, CCN1

    PubMed Central

    Duggirala, Aparna; Kimura, Tomomi E.; Sala-Newby, Graciela B.; Johnson, Jason L.; Wu, Yih-Jer; Newby, Andrew C.; Bond, Mark

    2015-01-01

    Elevation of intracellular cAMP concentration has numerous vascular protective effects that are in part mediated via actin cytoskeleton-remodelling and subsequent regulation of gene expression. However, the mechanisms are incompletely understood. Here we investigated whether cAMP-induced actin-cytoskeleton remodelling modulates VSMC behaviour by inhibiting expression of CCN1. In cultured rat VSMC, CCN1-silencing significantly inhibited BrdU incorporation and migration in a wound healing assay. Recombinant CCN1 enhanced chemotaxis in a Boyden chamber. Adding db-cAMP, or elevating cAMP using forskolin, significantly inhibited CCN1 mRNA and protein expression in vitro; transcriptional regulation was demonstrated by measuring pre-spliced CCN1 mRNA and CCN1-promoter activity. Forskolin also inhibited CCN1 expression in balloon injured rat carotid arteries in vivo. Inhibiting RhoA activity, which regulates actin-polymerisation, by cAMP-elevation or pharmacologically with C3-transferase, or inhibiting its downstream kinase, ROCK, with Y27632, significantly inhibited CCN1 expression. Conversely, expression of constitutively active RhoA reversed the inhibitory effects of forskolin on CCN1 mRNA. Furthermore, CCN1 mRNA levels were significantly decreased by inhibiting actin-polymerisation with latrunculin B or increased by stimulating actin-polymerisation with Jasplakinolide. We next tested the role of the actin-dependent SRF co-factor, MKL1, in CCN1 expression. Forskolin inhibited nuclear translocation of MKL1 and binding of MKL1 to the CCN1 promoter. Constitutively-active MKL1 enhanced basal promoter activity of wild-type but not SRE-mutated CCN1; and prevented forskolin inhibition. Furthermore, pharmacological MKL-inhibition with CCG-1423 significantly inhibited CCN1 promoter activity as well as mRNA and protein expression. Our data demonstrates that cAMP-induced actin-cytoskeleton remodelling regulates expression of CCN1 through MKL1: it highlights a novel cAMP-dependent mechanism controlling VSMC behaviour. PMID:25446180

  7. cAMP-induced actin cytoskeleton remodelling inhibits MKL1-dependent expression of the chemotactic and pro-proliferative factor, CCN1.

    PubMed

    Duggirala, Aparna; Kimura, Tomomi E; Sala-Newby, Graciela B; Johnson, Jason L; Wu, Yih-Jer; Newby, Andrew C; Bond, Mark

    2015-02-01

    Elevation of intracellular cAMP concentration has numerous vascular protective effects that are in part mediated via actin cytoskeleton-remodelling and subsequent regulation of gene expression. However, the mechanisms are incompletely understood. Here we investigated whether cAMP-induced actin-cytoskeleton remodelling modulates VSMC behaviour by inhibiting expression of CCN1. In cultured rat VSMC, CCN1-silencing significantly inhibited BrdU incorporation and migration in a wound healing assay. Recombinant CCN1 enhanced chemotaxis in a Boyden chamber. Adding db-cAMP, or elevating cAMP using forskolin, significantly inhibited CCN1 mRNA and protein expression in vitro; transcriptional regulation was demonstrated by measuring pre-spliced CCN1 mRNA and CCN1-promoter activity. Forskolin also inhibited CCN1 expression in balloon injured rat carotid arteries in vivo. Inhibiting RhoA activity, which regulates actin-polymerisation, by cAMP-elevation or pharmacologically with C3-transferase, or inhibiting its downstream kinase, ROCK, with Y27632, significantly inhibited CCN1 expression. Conversely, expression of constitutively active RhoA reversed the inhibitory effects of forskolin on CCN1 mRNA. Furthermore, CCN1 mRNA levels were significantly decreased by inhibiting actin-polymerisation with latrunculin B or increased by stimulating actin-polymerisation with Jasplakinolide. We next tested the role of the actin-dependent SRF co-factor, MKL1, in CCN1 expression. Forskolin inhibited nuclear translocation of MKL1 and binding of MKL1 to the CCN1 promoter. Constitutively-active MKL1 enhanced basal promoter activity of wild-type but not SRE-mutated CCN1; and prevented forskolin inhibition. Furthermore, pharmacological MKL-inhibition with CCG-1423 significantly inhibited CCN1 promoter activity as well as mRNA and protein expression. Our data demonstrates that cAMP-induced actin-cytoskeleton remodelling regulates expression of CCN1 through MKL1: it highlights a novel cAMP-dependent mechanism controlling VSMC behaviour.

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

    PubMed Central

    Nakayama, Madoka; Shoji, Wataru

    2017-01-01

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

  9. Urinary chemokine (C-C motif) ligand 2 (monocyte chemotactic protein-1) as a tubular injury marker for early detection of cisplatin-induced nephrotoxicity.

    PubMed

    Nishihara, Kumiko; Masuda, Satohiro; Shinke, Haruka; Ozawa, Aiko; Ichimura, Takaharu; Yonezawa, Atsushi; Nakagawa, Shunsaku; Inui, Ken-Ichi; Bonventre, Joseph V; Matsubara, Kazuo

    2013-02-15

    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 (5mg/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 (2mg/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.

  10. Natural nitration of CXCL12 reduces its signaling capacity and chemotactic activity in vitro and abrogates intra-articular lymphocyte recruitment in vivo

    PubMed Central

    Janssens, Rik; Mortier, Anneleen; Boff, Daiane; Vanheule, Vincent; Gouwy, Mieke; Franck, Charlotte; Larsen, Olav; Rosenkilde, Mette M.; Van Damme, Jo; Amaral, Flávio A.; Teixeira, Mauro M.; Struyf, Sofie; Proost, Paul

    2016-01-01

    The chemokine CXCL12/stromal cell-derived factor-1 is important for leukocyte migration to lymphoid organs and inflamed tissues and stimulates tumor development. In vitro, CXCL12 activity through CXCR4 is abolished by proteolytic processing. However, limited information is available on in vivo effects of posttranslationally modified CXCL12. Natural CXCL12 was purified from the coculture supernatant of stromal cells stimulated with leukocytes and inflammatory agents. In this conditioned medium, CXCL12 with a nitration on Tyr7, designated [3-NT7]CXCL12, was discovered via Edman degradation. CXCL12 and [3-NT7]CXCL12 were chemically synthesized to evaluate the biological effects of this modification. [3-NT7]CXCL12 recruited β-arrestin 2 and phosphorylated the Akt kinase similar to CXCL12 in receptor-transfected cells. Also the affinity of CXCL12 and [3-NT7]CXCL12 for glycosaminoglycans, the G protein-coupled chemokine receptor CXCR4 and the atypical chemokine receptor ACKR3 were comparable. However, [3-NT7]CXCL12 showed a reduced ability to enhance intracellular calcium concentrations, to generate inositol triphosphate, to phosphorylate ERK1/2 and to induce monocyte and lymphocyte chemotaxis in vitro. Moreover, nitrated CXCL12 failed to induce in vivo extravasation of lymphocytes to the joint. In summary, nitration on Tyr7 under inflammatory conditions is a novel natural posttranslational regulatory mechanism of CXCL12 which may downregulate the CXCR4-mediated inflammatory and tumor-promoting activities of CXCL12. PMID:27566567

  11. Mesenchymal stem cells and their chondrogenic differentiated and dedifferentiated progeny express chemokine receptor CCR9 and chemotactically migrate toward CCL25 or serum

    PubMed Central

    2013-01-01

    Introduction Guided migration of chondrogenically differentiated cells has not been well studied, even though it may be critical for growth, repair, and regenerative processes. The chemokine CCL25 is believed to play a critical role in the directional migration of leukocytes and stem cells. To investigate the motility effect of serum- or CCL25-mediated chemotaxis on chondrogenically differentiated cells, mesenchymal stem cells (MSCs) were induced to chondrogenic lineage cells. Methods MSC-derived chondrogenically differentiated cells were characterized for morphology, histology, immunohistochemistry, quantitative polymerase chain reaction (qPCR), surface profile, and serum- or CCL25-mediated cell migration. Additionally, the chemokine receptor, CCR9, was examined in different states of MSCs. Results The chondrogenic differentiated state of MSCs was positive for collagen type II and Alcian blue staining, and showed significantly upregulated expression of COL2A1and SOX9, and downregulated expression of CD44, CD73, CD90, CD105 and CD166, in contrast to the undifferentiated and dedifferentiated states of MSCs. For the chondrogenic differentiated, undifferentiated, and dedifferentiated states of MSCs, the serum-mediated chemotaxis was in a percentage ratio of 33%:84%:85%, and CCL25-mediated chemotaxis was in percentage ratio of 12%:14%:13%, respectively. On the protein level, CCR9, receptor of CCL25, was expressed in the form of extracellular and intracellular domains. On the gene level, qPCR confirmed the expression of CCR9 in different states of MSCs. Conclusions CCL25 is an effective cue to guide migration in a directional way. In CCL25-mediated chemotaxis, the cell-migration rate was almost the same for different states of MSCs. In serum-mediated chemotaxis, the cell-migration rate of chondrogenically differentiated cells was significantly lower than that in undifferentiated or dedifferentiated cells. Current knowledge of the surface CD profile and cell migration could be beneficial for regenerative cellular therapies. PMID:23958031

  12. Particle Swarm Optimization and Varying Chemotactic Step-Size Bacterial Foraging Optimization Algorithms Based Dynamic Economic Dispatch with Non-smooth Fuel Cost Functions

    NASA Astrophysics Data System (ADS)

    Praveena, P.; Vaisakh, K.; Rama Mohana Rao, S.

    The Dynamic economic dispatch (DED) problem is an optimization problem with an objective to determine the optimal combination of power outputs for all generating units over a certain period of time in order to minimize the total fuel cost while satisfying dynamic operational constraints and load demand in each interval. Recently social foraging behavior of Escherichia coli bacteria has been explored to develop a novel algorithm for distributed optimization and control. The Bacterial Foraging Optimization Algorithm (BFOA) is currently gaining popularity in the community of researchers, for its effectiveness in solving certain difficult real-world optimization problems. This article comes up with a hybrid approach involving Particle Swarm Optimization (PSO) and BFO algorithms with varying chemo tactic step size for solving the DED problem of generating units considering valve-point effects. The proposed hybrid algorithm has been extensively compared with those methods reported in the literature. The new method is shown to be statistically significantly better on two test systems consisting of five and ten generating units.

  13. A theoretical timeline for myocardial infarction: immunohistochemical evaluation and western blot quantification for Interleukin-15 and Monocyte chemotactic protein-1 as very early markers

    PubMed Central

    2014-01-01

    Background Experimental and human studies have demonstrated that innate immune mechanisms and consequent inflammatory reaction play a critical role in cardiac response to ischemic injury. Thus, the detection of immuno-inflammatory and cellular phenomena accompanying cardiac alterations during the early inflammatory phase of myocardial infarction (MI) may be an excellent diagnostic tool. Current knowledge of the chronology of the responses of myocardial tissue following the occurrence of ischemic insult, as well as the existence of numerous studies aiming to identify reliable markers in dating MI, induced us to investigate the myocardial specimens of MI fatal cases in order to better define the age of MI. Methods We performed an immunohistochemical study and a Western blot analysis to evaluate detectable morphological changes in myocardial specimens of fatal MI cases and to quantify the effects of cardiac expression of inflammatory mediators (CD15, IL-1β, IL-6, TNF-α, IL-15, IL-8, MCP-1, ICAM-1, CD18, tryptase) and structural and functional cardiac proteins. Results We observed a biphasic course of MCP-1: it was strongly expressed in the very early phase (0-4 hrs), to diminish in the early period (after 6-8 hrs). Again, our choice of IL-15 is explained by the synergism with neutrophilic granulocytes (CD15) and our study shows the potential for striking cytokine synergy in promoting fast, local neutrophil response in damaged tissues. A progressively stronger immunoreaction for the CD15 antibody was visible in the areas where the margination of circulating inflammatory cells was detectable, up to very strong expression in the oldest ones (>12 hours). Further, the induction of CD15, IL-15, MCP-1 expression levels was quantified by Western blot analysis. The results were as follows: IL-15/β-actin 0.80, CD15/β-actin 0.30, and MCP-1/β-actin 0.60, matching perfectly with the results of immunohistochemistry. Control hearts from traumatic death cases did not show any immunoreactivity to the pro-inflammatory markers, neither were there any reactions in Western blot analysis. Conclusions Essential markers (i.e. IL-15, MCP-1) are suitable indicators of myocardial response to ischemic insult involving very early phase reaction (inflammatory response and cytokine release). In the very near future, proteomics may help clinicians and pathologists to better understand mechanisms relating to cardiac repair and remodeling and provide targets for future therapies. PMID:24989171

  14. An emerging link in stem cell mobilization between activation of the complement cascade and the chemotactic gradient of sphingosine-1-phosphate.

    PubMed

    Ratajczak, Mariusz Z; Borkowska, Sylwia; Ratajczak, Janina

    2013-01-01

    Under steady-state conditions, hematopoietic stem/progenitor cells (HSPCs) egress from bone marrow (BM) and enter peripheral blood (PB) where they circulate at low levels. Their number in PB, however, increases significantly in several stress situations related to infection, organ/tissue damage, or strenuous exercise. Pharmacologically mediated enforced egress of HSPCs from the BM microenvironment into PB is called "mobilization", and this phenomenon has been exploited in hematological transplantology as a means to obtain HSPCs for hematopoietic reconstitution. In this review we will present the accumulated evidence that innate immunity, including the complement cascade and the granulocyte/monocyte lineage, and the PB plasma level of the bioactive lipid sphingosine-1-phosphate (S1P) together orchestrate this evolutionarily conserved mechanism that directs trafficking of HSPCs.

  15. Isolation of Terpenoids from the Stem of Ficus aurantiaca Griff and their Effects on Reactive Oxygen Species Production and Chemotactic Activity of Neutrophils.

    PubMed

    Mawa, Shukranul; Jantan, Ibrahim; Husain, Khairana

    2016-01-05

    Three new triterpenoids; namely 28,28,30-trihydroxylupeol (1); 3,21,21,26-tetrahydroxy-lanostanoic acid (2) and dehydroxybetulinic acid (3) and seven known compounds; i.e., taraxerone (4); taraxerol (5); ethyl palmitate (6); herniarin (7); stigmasterol (8); ursolic acid (9) and acetyl ursolic acid (10) were isolated from the stem of Ficus aurantiaca Griff. The structures of the compounds were established by spectroscopic techniques. The compounds were evaluated for their inhibitory effects on polymorphonuclear leukocyte (PMN) chemotaxis by using the Boyden chamber technique and on human whole blood and neutrophil reactive oxygen species (ROS) production by using a luminol-based chemiluminescence assay. Among the compounds tested, compounds 1-4, 6 and 9 exhibited strong inhibition of PMN migration towards the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) with IC50 values of 6.8; 2.8; 2.5; 4.1; 3.7 and 3.6 μM, respectively, comparable to that of the positive control ibuprofen (6.7 μM). Compounds 2-4, 6, 7 and 9 exhibited strong inhibition of ROS production of PMNs with IC50 values of 0.9; 0.9; 1.3; 1.1; 0.5 and 0.8 μM, respectively, which were lower than that of aspirin (9.4 μM). The bioactive compounds might be potential lead molecules for the development of new immunomodulatory agents to modulate the innate immune response of phagocytes.

  16. Expression and secretion of chemotactic cytokines IL-8 and MCP-1 by human endothelial cells after Rickettsia rickettsii infection: regulation by nuclear transcription factor NF-kappaB.

    PubMed

    Clifton, Dawn R; Rydkina, Elena; Huyck, Heidie; Pryhuber, Gloria; Freeman, Robert S; Silverman, David J; Sahni, Sanjeev K

    2005-08-01

    Infection of endothelial cells (EC) with Rickettsia rickettsii results in Rocky Mountain spotted fever, an acute illness characterized by systemic inflammation. Interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) are important chemokines for activating neutrophils and monocytes, respectively, and recruiting these circulating immune cells to the sites of inflammation. In this study, we have measured the expression and secretion of these chemokines during R. rickettsii infection of cultured human EC. In comparison to uninfected controls, increased mRNA expression of IL-8 and MCP-1 in R. rickettsii-infected EC was evident as early as 3 h and was sustained up to 21 h. Subsequent analysis of culture supernatants revealed significantly enhanced secretion of both chemokines at 3, 8, and 18 h post-infection (5-28-fold increase in IL-8 and 4-16-fold increase in MCP-1). The presence of peptide-aldehyde compound MG132 to inhibit proteasome-mediated degradation of the inhibitory protein IkappaBalpha and synthetic peptide SN-50 to inhibit the nuclear translocation of nuclear factor-kappa B (NF-kappaB) resulted in significant inhibition of the chemokine response. Also, T24 cells expressing a super-repressor mutant of IkappaBalpha (to render NF-kappaB inactivatable) secreted significantly lower quantities of IL-8 than mock-transfected cells. A neutralizing antibody against IL-1alpha or an IL-1 specific receptor antagonist had no effect on the early phase of R. rickettsii-induced NF-kappaB activation and IL-8/ MCP-1 secretion at 3 h. Both of these treatments, however, diminished late-phase NF-kappaB activation by about 33% and only partially suppressed the infection-induced chemokine release at 21 h. Thus, while chemokine response early during the infection likely depends on the direct activation of NF-kappaB, subtle autocrine effects of newly synthesized IL-1alpha may contribute, in part, to the control of NF-kappaB activation and chemokine production at later times. These findings implicate a prominent role for host EC in recruiting immune cells to the site of inflammation during Rickettsia infection and provide important insights to further our understanding of the pathogenesis of spotted fever group rickettsioses.

  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. Regulation of Monocyte Chemotactic Protein-1 secretion by the Two-Pore-Domain Potassium (K2P) channel TREK-1 in human alveolar epithelial cells.

    PubMed

    Schwingshackl, Andreas; Teng, Bin; Ghosh, Manik; Waters, Christopher M

    2013-01-01

    We recently proposed a role for the 2-pore-domain K(+) (K2P) channel TREK-1 in the regulation of cytokine release from alveolar epithelial cells (AECs) by demonstrating decreased IL-6 secretion from TREK-1 deficient cells, but the effects of altered TREK-1 expression on other inflammatory mediators remain poorly understood. We now examined the role of TREK-1 in TNF-α-induced MCP-1 release from human A549 cells. We hypothesized that TREK-1 regulates TNF-α-induced MCP-1 secretion via c-Jun N-terminal kinases (JNK)- and protein kinase-C (PKC)-dependent pathways. In contrast to IL-6 secretion, we found that TREK-1 deficiency resulted in increased MCP-1 production and secretion, although baseline MCP-1 gene expression was unchanged in TREK-1 deficient cells. In contrast to TREK-1 deficient AECs, overexpression of MCP-1 had no effect on MCP-1 secretion. Phosphorylation of JNK1/2/3 was increased in TREK-1 deficient cells upon TNF-α stimulation, but pharmacological inhibition of JNK1/2/3 decreased MCP-1 release from both control and TREK-1 deficient cells. Similarly, pharmacological inhibition of PKC decreased MCP-1 secretion from control and TREK-1 deficient cells, suggesting that alterations in JNK and PKC signaling pathways were unlikely the cause for the increased MCP-1 secretion from TREK-1 deficient cells. Furthermore, MCP-1 secretion from control and TREK-1 deficient cells was independent of extracellular Ca(2+) but sensitive to inhibition of intracellular Ca(2+) reuptake mechanisms. In summary, we report for the first time that TREK-1 deficiency in human AECs resulted in increased MCP-1 production and secretion, and this effect appeared unrelated to alterations in JNK-, PKC- or Ca(2+)-mediated signaling pathways in TREK-1 deficient cells.

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

    PubMed

    Tasaki, Sohei; Nakayama, Madoka; Shoji, Wataru

    2017-01-01

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

  20. Downmodulation of CCR7 by HIV-1 Vpu results in impaired migration and chemotactic signaling within CD4⁺ T cells.

    PubMed

    Ramirez, Peter W; Famiglietti, Marylinda; Sowrirajan, Bharatwaj; DePaula-Silva, Ana Beatriz; Rodesch, Christopher; Barker, Edward; Bosque, Alberto; Planelles, Vicente

    2014-06-26

    The chemokine receptor CCR7 plays a crucial role in the homing of central memory and naive T cells to peripheral lymphoid organs. Here, we show that the HIV-1 accessory protein Vpu downregulates CCR7 on the surface of CD4(+) T cells. Vpu and CCR7 were found to specifically interact and colocalize within the trans-Golgi network, where CCR7 is retained. Downmodulation of CCR7 did not involve degradation or endocytosis and was strictly dependent on Vpu expression. Stimulation of HIV-1-infected primary CD4(+) T cells with the CCR7 ligand CCL19 resulted in reduced mobilization of Ca(2+), reduced phosphorylation of Erk1/2, and impaired migration toward CCL19. Specific amino acid residues within the transmembrane domain of Vpu that were previously shown to be critical for BST-2 downmodulation (A14, A18, and W22) were also necessary for CCR7 downregulation. These results suggest that BST-2 and CCR7 may be downregulated via similar mechanisms.

  1. 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

  2. Molecular phylogenetics of subclass Peritrichia (Ciliophora: Oligohymenophorea) based on expanded analyses of 18S rRNA sequences.

    PubMed

    Utz, Laura R P; Eizirik, Eduardo

    2007-01-01

    Phylogenetic relationships among peritrich ciliates remain unclear in spite of recent progress. To expand the analyses performed in previous studies, and to statistically test hypotheses of monophyly, we analyzed a broad sample of 18s rRNA sequences (including 15 peritrich genera), applying a conservative alignment strategy and several phylogenetic approaches. The main results are that: (i) the monophyly of Peritrichia cannot be rejected; (ii) the two main clades of Sessilida do not correspond to formally recognized taxa; (iii) the monophyly of genera Vorticella and Epistylis is significantly rejected; and (iv) morphological structures commonly used in peritrich taxonomy may be evolutionarily labile.

  3. 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

  4. Laminar flow assisted anisotropic bacteria absorption for chemotaxis delivery of bacteria-attached microparticle

    NASA Astrophysics Data System (ADS)

    Huh, Keon; Oh, Darong; Son, Seok Young; Yoo, Hyung Jung; Song, Byeonghwa; Cho, Dong-il Dan; Seo, Jong-Mo; Kim, Sung Jae

    2016-12-01

    The concepts of microrobots has been drawn significant attentions recently since its unprecedented applicability in nanotechnology and biomedical field. Bacteria attached microparticles presented in this work are one of pioneering microrobot technology for self-propulsion or producing kinetic energy from ambient for their motions. Microfluidic device, especially utilizing laminar flow characteristics, were employed for anisotropic attachment of Salmonella typhimurium flagellated chemotactic bacteria to 30 um × 30 um and 50 um × 50 um microparticles that made of biodegradable polymer. Any toxic chemicals or harmful treatments were excluded during the attachment process and it finished within 100 s for the anisotropic attachment. The attachments were directly confirmed by fluorescent intensity changes and SEM visualization. Chemotaxis motions were tracked using aspartate and the maximum velocity of the bacteria-attached microrobot was measured to be 5 um/s which is comparable to prior state of art technologies. This reusable and scalable method could play a key role in chemotaxis delivery of functional microparticles such as drug delivery system.

  5. Halomonas titanicae sp. nov., a halophilic bacterium isolated from the RMS Titanic.

    PubMed

    Sánchez-Porro, Cristina; Kaur, Bhavleen; Mann, Henrietta; Ventosa, Antonio

    2010-12-01

    A Gram-negative, heterotrophic, aerobic, non-endospore-forming, peritrichously flagellated and motile bacterial strain, designated BH1(T), was isolated from samples of rusticles, which are formed in part by a consortium of micro-organisms, collected from the RMS Titanic wreck site. The strain grew optimally at 30-37°C, pH 7.0-7.5 and in the presence of 2-8 % (w/v) NaCl. We carried out a polyphasic taxonomic study in order to characterize the strain in detail. Phylogenetic analyses based on 16S rRNA gene sequence comparison indicated that strain BH1(T) clustered within the branch consisting of species of Halomonas. The most closely related type strains were Halomonas neptunia (98.6 % 16S rRNA sequence similarity), Halomonas variabilis (98.4 %), Halomonas boliviensis (98.3 %) and Halomonas sulfidaeris (97.5 %). Other closely related species were Halomonas alkaliphila (96.5 % sequence similarity), Halomonas hydrothermalis (96.3 %), Halomonas gomseomensis (96.3 %), Halomonas venusta (96.3 %) and Halomonas meridiana (96.2 %). The major fatty acids of strain BH1(T) were C(18 : 1)ω7c (36.3 %), C(16 : 0) (18.4 %) and C(19 : 0) cyclo ω8c (17.9 %). The DNA G+C content was 60.0 mol% (T(m)). Ubiquinone 9 (Q-9) was the major lipoquinone. The phenotypic features, fatty acid profile and DNA G+C content further supported the placement of strain BH1(T) in the genus Halomonas. DNA-DNA hybridization values between strain BH1(T) and H. neptunia CECT 5815(T), H. variabilis DSM 3051(T), H. boliviensis DSM 15516(T) and H. sulfidaeris CECT 5817(T) were 19, 17, 30 and 29 %, respectively, supporting the differential taxonomic status of BH1(T). On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain BH1(T) is considered to represent a novel species, for which the name Halomonas titanicae sp. nov. is proposed. The type strain is BH1(T) (=ATCC BAA-1257(T) =CECT 7585(T) =JCM 16411(T) =LMG 25388(T)).

  6. 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

  7. 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).

  8. 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

  9. Some dinophycean red tide plankton species generate a superoxide scavenging substance.

    PubMed

    Sato, Emiko; Niwano, Yoshimi; Matsuyama, Yukihiko; Kim, Daekyung; Nakashima, Takuji; Oda, Tatsuya; Kohno, Masahiro

    2007-03-01

    Recent studies indicate that some raphidophycean red tide flagellates produce substances able to scavenge superoxide, whereas there have been no reports on superoxide scavenger production by dinophycean red tide flagellates. In this study, we examined the superoxide-scavenging activity of aqueous extracts from dinophycean red tide flagellates, Gymnodinium spp., Scrippsiella trochoidea, and Karenia sp., by a luminol analog L-012-dependent chemiluminescence (CL) method and an electron spin resonance (ESR)-spin trapping method, and compared the activity to that of raphidophycean red tide flagellates, Chattonella spp., Heterosigma akashiwo, and Fibrocapsa japonica. In the experiment applying the L-012-dependent CL method, only the aqueous extracts from raphidophycean red tide flagellates showed superoxide-scavenging activity. On the other hand, applying the ESR-spin trapping method, we found that the aqueous extracts from dinophycean red tide flagellates also showed superoxide-scavenging activity. This is the first report on the production of a superoxide-scavenger by dinophycean red tide flagellates.

  10. 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.

  11. Synergistic enhancement of cytokine-induced human monocyte matrix metalloproteinase-1 by C-reactive protein and oxidized LDL through differential regulation of monocyte chemotactic protein-1 and prostaglandin E2.

    PubMed

    Zhang, Yahong; Wahl, Larry M

    2006-01-01

    C-reactive protein (CRP) and oxidized LDL (ox-LDL) are associated with inflammatory lesions, such as coronary artery disease, in which monocytes and matrix metalloproteinases (MMPs) may play a major role in the rupture of atherosclerotic plaques. Monocytes are recruited to inflammation sites by monocyte chemoattractant protein-1 (MCP-1), which may also participate in the activation of monocytes. The objective of this study was to compare the individual and combined effect of CRP and ox-LDL on human monocyte MMP-1 and the role of MCP-1 in this effect. Although CRP or ox-LDL failed to induce MMP-1 in control monocytes, these molecules enhanced MMP-1 production induced by tumor necrosis factor alpha (TNF-alpha) and granulocyte macrophage-colony stimulating factor (GM-CSF) with a synergistic increase in MMP-1 occurring in the presence of both mediators. Enhancement of MMP-1 by CRP and ox-LDL was attributable to a differential increase in MCP-1 and prostaglandin E2(PGE2). CRP, at physiological concentrations, induced high levels of MCP-1 and relatively low levels of PGE2, whereas ox-LDL caused a significant enhancement of PGE2 with little affect on MCP-1. Accordingly, CRP- and ox-LDL-induced MMP-1 production by monocytes was inhibited by anti-MCP-1 antibodies and indomethacin, respectively. Moreover, addition of exogenous MCP-1 or PGE2 enhanced MMP-1 production by TNF-alpha- and GM-CSF-stimulated monocytes. These results show that the combination of CRP and ox-LDL can cause a synergistic enhancement of the role of monocytes in inflammation, first, by increasing MCP-1, which attracts more monocytes and directly enhances MMP-1 production by activated monocytes, and second, by elevating PGE2 production, which also leads to higher levels of MMP-1.

  12. Independent expression of human. alpha. or. beta. platelet-derived growth factor receptor cDNAs in a naive hematopoietic cell leads to functional coupling with mitogenic and chemotactic signaling pathways

    SciTech Connect

    Matsui, T.; Pierce, J.H.; Fleming, T.P.; LaRochelle, W.J.; Ruggiero, M.; Aaronson, S.A. ); Greenberger, J.S. )

    1989-11-01

    Distinct genes encode {alpha} and {beta} platelet-derived growth factor (PDGF) receptors that differ in their abilities to be triggered by three dimeric forms of the PDGF molecule. The authors show that PDGF-receptor mitogenic function can be reconstituted in a naive hematopoietic cell line by introduction of expression vectors for either {alpha} or {beta} PDGF receptor cDNAs. Thus, each receptor is independently capable of coupling with mitogenic signal-transduction pathways inherently present in these cells. Activation of either receptor also resulted in chemotaxis, alterations in inositol lipid metabolism, and mobilization of intracellular Ca{sup 2+}. The magnitude of these functional responses correlated well with the binding properties of the different PDGF isoforms to each receptor. Thus, availability of specific PDGF isoforms and relative expression of each PDGF-receptor gene product are major determinants of the spectrum of known PDGF responses.

  13. Tenidap decreases IL-8 and monocyte chemotactic peptide-1 (MCP-1) mRNA expression in the synovial tissue of rabbits with antigen arthritis and in cultured synovial cells

    PubMed Central

    Palacios, I; Lopez-Armada, M J; Hernandez, P; Sanchez-Pernaute, O; Gutierrez, S; Miguelez, R; Martinez, J; Egido, J; Herrero-Beaumont, G

    1998-01-01

    Since IL-8 and MCP-1 are chemoattractant proteins that participate in the recruitment of inflammatory cells into the arthritic joint, we examined the effects of tenidap, a new anti-inflammatory drug of the oxindole family, on IL-8 and MCP-1 expression in the joints of rabbits with acute antigen arthritis. The model was induced by injecting 5 mg/ml ovalbumin into the knees of 20 preimmunized rabbits. Animals were randomized into two groups: treated with tenidap (15 mg/kg per 12 h), or untreated. The effect of tenidap treatment was evaluated on chemokine production in synovial membranes of rabbits with arthritis and in cultured monocytic and synovial cells (SC). By immunoperoxidase staining, chemokines were localized in the synovial tissue. Chemokine messenger RNA levels in the synovial membranes and in cultured cells were analysed by reverse transcription-polymerase chain reaction (RT-PCR). At the end of the study, tenidap significantly reduced neutrophil infiltration into the joint cavity (27 ± 4 × 106 cells/ml versus 45 ± 6 × 106 cells/ml in untreated; P < 0.05), and synovial effusion (134 ± 15 μl versus 236 ± 19 μl in untreated; P < 0.005). Untreated rabbits showed synovial membrane up-regulation in mRNA expression of IL-8 and MCP-1 (11- and seven-fold versus healthy rabbits, respectively) that was markedly decreased by tenidap (two- and three-fold versus healthy rabbits, respectively). IL-8 and MCP-1 were localized in the synovial tissue in a perivascular pattern and areas of the interstitium and lining, mostly coinciding with cell infiltration. Tenidap also reduced the accumulation of IL-8 and MCP-1 proteins. In cultured synovial and monocytic cells, tumour necrosis factor-alpha (TNF-α) elicited an increase in gene expression of IL-8 (four- and nine-fold, respectively) and MCP-1 (nine- and four-fold, respectively) that was significantly reversed in both cell types by 10 μm tenidap. These results suggest that the beneficial effect of tenidap in acute antigen arthritis could be related to the down-regulation in gene expression and synthesis of IL-8 and MCP-1, two key chemokines involved in the recruitment of inflammatory cells. PMID:9528904

  14. Trypanosomatid protozoa in fruit of Solanaceae in southeastern Brazil.

    PubMed

    Kastelein, P; Camargo, E P

    1990-01-01

    Fruits of cultivated and indigenous Solanaceae from Southeastern Brazil have been examined for the presence of trypanosomatid flagellates. The 14 species found infected were: Capsicum annuum, C. praetermissum, Lycopersicon esculentum, Nicandra physaloides, Physalis angulata, Solanum sp., S. americanum, S. concinnum, S. diflorum, S. erianthum, S. gilo, S. robustum, S. variable and S. viarum. The pentatomid hemipteran Arvelius albopunctatus experimentally transmitted flagellates to fruits of some species. Cultures of flagellates were obtained from fruits of eight species of Solanaceae and from A. albopunctatus.

  15. The Effect of Controlled Pressure Changes on the Stimulation of Bioluminescence in Pyrocystis Lunula.

    DTIC Science & Technology

    1984-07-02

    observed (Tett and Kelly, 1973). While considerable variations in morphological characteristics exist among different species, all dino - flagellates ...share certain structural features. The dino - flagellates have two flagella, one lying in a groove along the main axis of the cell, and the other along...The relation of photoinhibition and photo- synthesis is evident because all the photosynthetic dino - flagellates photoinhibit, while none of the non

  16. A molecular phylogenetic investigation of zoothamnium (ciliophora, peritrichia, sessilida).

    PubMed

    Clamp, John C; Williams, Daniel

    2006-01-01

    The gene coding for 18S small subunit ribosomal RNA (ssu rRNA) was sequenced in seven free-living, marine species of the sessiline peritrich genus Zoothamnium. These were Zoothamnium niveum, Zoothamnium alternans, Zoothamnium pelagicum, and four unidentified species. The ssu rRNA gene also was sequenced in Vorticella convallaria, Vorticella microstoma, and in an unidentified, freshwater species of Vorticella. Phylogenetic trees were constructed using these new sequences to test a previously published phylogenetic association between Zoothamnium arbuscula, currently in the family Zoothamniidae, and peritrichs in the family Vorticellidae. Trees constructed by means of neighbor-joining, maximum parsimony, maximum likelihood, and Bayesian inference methods all had similar topologies. The seven new sequences of Zoothamnium species grouped into three well-supported clades, each of which contained a diversity of morphological types. The three clades formed a poorly supported, larger clade that was deeply divergent from Z. arbuscula, which remained more closely associated with vorticellid peritrichs. It is apparent that Zoothamnium is a richly diverse genus and that a much more intensive investigation, involving both morphological and molecular data and a wider selection of species, will be necessary to resolve its phylogeny. A greater amount of molecular diversity than is predicted by morphological data exists within all major clades of sessiline peritrichs that have been included in molecular phylogenies, indicating that characteristics of stalk and peristomial structure traditionally used to differentiate taxa at the generic level and above may not be uniformly reliable.

  17. Independent emergence of biotype 2 Yersinia ruckeri in the United States and Europe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biotype 2 (BT2) variants of the bacterium Yersinia ruckeri are an increasing disease problem in United States (US) and European aquaculture and have been characterized as serovar 1 isolates that lack peritrichous flagella and secreted phospholipase activity. The emergence of this biotype has been as...

  18. 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...

  19. Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). BAY SCALLOP,

    DTIC Science & Technology

    1983-10-01

    combination of naked flagellates (Isochrysis galbana Predators and Monochrysis lutheri ) (Loosanoff and Davis 1963; Sastry 1965). In shallow water areas...either flagellates (M. lutheri (Callinectes sapidus) (Castagna 1975). and Dunaliella tertiolecta) or diatoms In water deeper than 2 m (6.6 ft

  20. Generation of reactive oxygen species by raphidophycean phytoplankton.

    PubMed

    Oda, T; Nakamura, A; Shikayama, M; Kawano, I; Ishimatsu, A; Muramatsu, T

    1997-10-01

    Chattonella marina, a raphidophycean flagellate, is one of the most toxic red tide phytoplankton and causes severe damage to fish farming. Recent studies demonstrated that Chattonella sp. generates superoxide (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (.OH), which may be responsible for the toxicity of C. marina. In this study, we found the other raphidophycean flagellates such as Heterosigma akashiwo, Olisthodiscus luteus, and Fibrocapsa japonica also produce O2- and H2O2 under normal growth condition. Among the flagellate species tested, Chattonella has the highest rates of production of O2- and H2O2 as compared on the basis of cell number. This seems to be partly due to differences in their cell sizes, since Chattonella is larger than other flagellate species. The generation of O2- by these flagellate species was also confirmed by a chemiluminescence assay by using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin++ +-3-one (MCLA). All these raphidophycean flagellates inhibited the proliferation of a marine bacterium, Vibrio alginolyticus, in a flagellates/bacteria co-culture system, and their toxic effects were suppressed by the addition of superoxide dismutase (SOD) or catalase. Our results suggest that the generation of reactive oxygen species is a common feature of raphidophycean flagellates.

  1. Vectors of Leishmania braziliensis in the Petén, Guatemala.

    PubMed

    Rowton, E; de Mata, M; Rizzo, N; Navin, T; Porter, C

    1991-12-01

    During a 1-year study, 13 species of sand fly were collected in bite-landing collections on human attractants in Tikal, Guatemala. Using isoenzyme analysis, Leishmania braziliensis was identified among isolates from Lutzomyia ovallesi, Lu. panamensis, and Lu. ylephiletor. Lutzomyia ovallesi, Lu. shannoni, and Lu. cruciata were found with flagellates whose isoenzyme patterns matched unidentified flagellates isolated from a patient with mucosal lesions.

  2. A Prototype Bioluminescence Photometer

    DTIC Science & Technology

    1982-02-01

    Seliger et al., 1962) provided maximum mechanical stimulation to dino - flagellates , and incorporated light baffles to permit continuous measurement...was deployed in a shallow coastal area relatively free of any mixing. The principle bioluminescent plankton were the dino - flagellates , as evidenced

  3. Can unicells increase their nutrient uptake by swimming?

    NASA Astrophysics Data System (ADS)

    Langlois, Vincent; Andersen, Anders; Bohr, Tomas; Visser, André; Kiørboe, Thomas

    2008-11-01

    We introduce two simple models for the flow generated by a self-propelled flagellate: a sphere propelled by a cylindrical flagellum and one propelled by an external point force. We use these models to examine the role of advection in enhancing feeding rates in 3 situations: (i) osmotroph feeding on dissolved molecules, (ii) interception feeding flagellates feeding on non-motile prey particles, and (iii) interception feeders feeding on motile prey (such as bacteria). We show that the Sherwood number is close to unity for osmotrophic flagellates, as suggested by most previous models. However, a more correct representation of the flow field than that predicted by a naive sinking sphere model leads to substantially higher clearance rates for interception feeding flagellates. We finally demonstrate that prey motility significantly enhances prey encounter rates in interception feeding flagellates and in fact often is much more important for food acquisition than the feeding current.

  4. Grazing Characteristics and Growth Efficiencies at Two Different Temperatures for Three Nanoflagellates Fed with Vibrio Bacteria at Three Different Concentrations.

    PubMed

    Ishigaki, T.; Sleigh, M.A.

    2001-04-01

    Small inocula of one of the flagellates Paraphysomonas imperforata, Pteridomonas danica, and Cafeteria roenbergensis were added to suspensions of the bacterium Vibrio natriegens at each of three concentrations between 107 and 108 cells ml-1 and incubated at each of the temperatures 10 degrees C and 25 degrees C. Samples were taken at intervals for counting the flagellates and bacteria to determine the timing of the maximum of flagellate numbers and the concentrations at that time. Measurements of the protein concentration of the suspensions during incubation were used to determine the gross growth efficiency (GGE) or yield of flagellate grazing in each experiment. The most effective grazer was Pteridomonas, followed by Paraphysomonas, with Cafeteria being least effective, as judged by the threshold bacterial concentrations at which flagellate multiplication ceased, which were about 2 x 105, 2 x 106, and 2 x 107, respectively, and by the finding that Pteridomonas consumed 99%, Paraphysomonas about 95%, and Cafeteria only 60-70% of the available bacteria in the experiments. Peak concentrations of flagellates were reached later at the lower temperature, but the numbers of flagellates produced and of bacteria eaten were of a similar order at the two temperatures and the GGE was only slightly higher at the lower temperature. The time taken to reach peak flagellate numbers changed little with a threefold increase in bacterial concentrations, but the GGE increased and the numbers of bacteria eaten to produce one flagellate decreased when the bacterial concentration was increased. The three flagellates show clear evidence of niche specialization in differences in thresholds of bacterial prey concentration.

  5. Phosphate taxis in Pseudomonas aeruginosa.

    PubMed

    Kato, J; Ito, A; Nikata, T; Ohtake, H

    1992-08-01

    Pseudomonas aeruginosa was shown to be attracted to phosphate. The chemotactic response was induced by phosphate starvation. The specificity of chemoreceptors for phosphate was high so that no other tested phosphorus compounds elicited a chemotactic response as strong as that elicited by phosphate. Competition experiments showed that the chemoreceptors for phosphate appeared to be different from those for the common amino acids. Mutants constitutive for alkaline phosphatase showed the chemotactic response to phosphate regardless of whether the cells were starved for phosphate.

  6. Osteopontin CD44 Interaction: A Novel Mechanism for the Selective Homing of Breast Tumor Cells into Bone

    DTIC Science & Technology

    2001-06-01

    Introduction cancer pharmacology, and im- structure - function analysis of munology he served on the fac- extracellular matrix molecules What are the traits...isolated a hexa peptide from osteopontin that is chemotactic to tumor cells. Antibodies raised against this peptide neutralize the chemotactic response of ...circulating breast tumor cells expressing specific CD44v splice variants. We have isolated a peptide analogue of the chemotactic domain (PepL) that

  7. Plasma-dependent chemotaxis of macrophages toward BCG cell walls and the mycobacterial glycolipid P3.

    PubMed

    Kelly, M T

    1977-01-01

    BCG cell walls, associated with oil droplets in the form of emulsions in saline, generate macrophage chemotactic activity from fresh guinea pig plasma. Serum and heat-inactivated plasma were inactive, suggesting involvement of complement or fibrinogen-derived chemotactic factors. Suspensions of cell walls and oil droplets each generated chemotactic activity from plasma, and the activity of the cell wall vaccine was due to the additive effects of these two components. A mycobacterial glycolipid (P3), which is a constituent of BCG cell walls, also had plasma-dependent chemotactic activity. The results suggest that macrophage chemotaxis may be an important part of the immunopotentiating activity of these mycobacterial products.

  8. FlhG employs diverse intrinsic domains and influences FlhF GTPase activity to numerically regulate polar flagellar biogenesis in Campylobacter jejuni.

    PubMed

    Gulbronson, Connor J; Ribardo, Deborah A; Balaban, Murat; Knauer, Carina; Bange, Gert; Hendrixson, David R

    2016-01-01

    Flagellation in polar flagellates is one of the rare biosynthetic processes known to be numerically regulated in bacteria. Polar flagellates must spatially and numerically regulate flagellar biogenesis to create flagellation patterns for each species that are ideal for motility. FlhG ATPases numerically regulate polar flagellar biogenesis, yet FlhG orthologs are diverse in motif composition. We discovered that Campylobacter jejuni FlhG is at the center of a multipartite mechanism that likely influences a flagellar biosynthetic step to control flagellar number for amphitrichous flagellation, rather than suppressing activators of flagellar gene transcription as in Vibrio and Pseudomonas species. Unlike other FlhG orthologs, the FlhG ATPase domain was not required to regulate flagellar number in C. jejuni. Instead, two regions of C. jejuni FlhG that are absent or significantly altered in FlhG orthologs are involved in numerical regulation of flagellar biogenesis. Additionally, we found that C. jejuni FlhG influences FlhF GTPase activity, which may mechanistically contribute to flagellar number regulation. Our work suggests that FlhG ATPases divergently evolved in each polarly flagellated species to employ different intrinsic domains and extrinsic effectors to ultimately mediate a common output - precise numerical control of polar flagellar biogenesis required to create species-specific flagellation patterns optimal for motility.

  9. Description of Epistylis riograndensis n.sp. (Ciliophora: Peritrichia) found in an artificial lake in Southern Brazil.

    PubMed

    Utz, Laura R P; Farias, Ana Carolina Silva Rodrigues; Freitas, Eduarda Correa; de Araújo, Gabriella Oliveira

    2014-10-03

    Epistylis riograndensis n. sp., a freshwater peritrich hosting symbiotic algae in its cytoplasm, was collected from an artificial lake, in a Botanical garden in Southern Brazil. Its detailed morphology was investigated using live and silver-stained specimens. The colonial sessile E. riograndensis has elongate zooids measuring, on average, 162 μm in length and 45 μm in width. A single contractile vacuole located near the infundibulum and a C-shaped macronucleus located transversely in the adoral half of the cell were also observed. The oral infraciliature revealed in silver-stained specimens was typical of peritrich ciliates. Three infundibular polykineties consisting of 3 rows of kinetosomes were observed. Molecular analyses of 18s rDNA placed E. riograndensis among other Epistylis species in the Order Vorticellida.

  10. 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

  11. Flagella and pili of iron-oxidizing thiobacilli isolated from a uranium mine in northern Ontario, Canada

    SciTech Connect

    DiSpirito, A.A.; Silver, M.; Voss, L.; Tuovinen, O.H.

    1982-05-01

    Five strains of Thiobacillus ferrooxidans, which included three recent isolates from a uranium mine, possessed flagella. Three of the strains had several pili per cell. The dimensions, fine structure, and orientation of the flagella were different. Both polar and peritrichous flagella were observed, indicating strain-dependent ultrastructural variation in acidophilic thiobacilli. Neither flagella nor pili were detected in eight other strains of T. ferrooxidans and two strains of Thiobacillus acidophilus by electron microscopy, although all of the cultures contained motile cells.

  12. 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.