The Experts below are selected from a list of 6477 Experts worldwide ranked by ideXlab platform

Hideyuki Arata - One of the best experts on this subject based on the ideXlab platform.

  • Chemotaxis Assay of plant parasitic nematodes on a gel filled microchannel device
    Sensors and Actuators B-chemical, 2015
    Co-Authors: Hirotaka Hida, Hidetaka Nishiyama, Shinichiro Sawa, Tetsuya Higashiyama, Hideyuki Arata
    Abstract:

    Abstract Plant-parasitic nematodes substantially damage a wide variety of agricultural crops worldwide. The Chemotaxis of nematodes is a key factor in their parasitic relationship with plants. Therefore, studies on nematode Chemotaxis are essential for devising efficient and environmentally friendly management methods. In this paper, we report a new, efficient, and quantitative method to analyze Chemotaxis of the plant-parasitic nematode, Meloidogyne incognita , using a gel-filled microchannel device. We quantitatively defined time-dependent concentration gradients of chemicals in the gel-filled microchannel by measuring changes in the fluorescence intensity of fluorescein. We also developed a protocol to allow the nematodes to move around in the microchannels by loading an agarose gel with optimum concentration. Using this novel Assay method, we have shown that potassium nitrate (KNO 3 ) stimulates the behavior of M. incognita and can have both repellent and attractant effects, depending on the concentration gradient. This newly developed quantitative Chemotaxis Assay method can be used to screen and identify new candidate molecules that repel or attract nematodes, and also to analyze the repellent/attractant properties of those molecules toward nematodes.

  • high throughput Chemotaxis Assay of plant parasitic nematode toward green agriculture
    18th International Conference on Miniaturized Systems for Chemistry and Life Sciences MicroTAS 2014, 2014
    Co-Authors: Hirotaka Hida, M Matsumura, Isaku Kanno, Hidetaka Nishiyama, Shinichiro Sawa, Tetsuya Higashiyama, Hideyuki Arata
    Abstract:

    This paper presents a new microsystem for simple and high-throughput Chemotaxis Assay of plantparasitic nematodes Meloidogyne incognita. To improve an efficiency of Chemotaxis Assay, we developed a PDMS (Polydimethylsiloxane) microsystem, which can generate various chemical conditions in multiple microchannels at once. By using this system, we successfully identified a lower limitation of the concentration gradient of KNO3 solution, which can act as a repellent for the nematode M. incognita.

  • on chip Chemotaxis Assay of plant parasitic nematode towards increasing global crop productivity
    17th International Conference on Miniaturized Systems for Chemistry and Life Sciences MicroTAS 2013, 2013
    Co-Authors: Hirotaka Hida, Hidetaka Nishiyama, Shinichiro Sawa, Tetsuya Higashiyama, Hideyuki Arata
    Abstract:

    This paper reports a new method for simple and efficient on-chip Chemotaxis Assay of plant-parasitic nematode, Meloidogyne incognita. To precisely characterize Chemotaxis of the nematodes, we have developed a polydimethylsiloxane (PDMS) T-shaped microchannel-device which has a pair of micro-slits connected by narrow microchannel arrays with chemical inlets. This microchannel-device can efficiently create controllable chemical conditions for analyzing nematodes behavior. We have established a protocol to allow nematodes to swim freely in the microchannel by loading an agarose gel. Then, KNO3 was firstly identified as attractant/repellent and the nematode behavior depending on chemical conditions was quantitatively investigated. This method might contribute to global food and energy problems by improving crop productivity.

Karen M. Ottemann - One of the best experts on this subject based on the ideXlab platform.

  • Two Spatial Chemotaxis Assays: The Nutrient-Depleted Chemotaxis Assay and the Agarose-Plug-Bridge Assay
    Methods in molecular biology (Clifton N.J.), 2018
    Co-Authors: Victoria Korolik, Karen M. Ottemann
    Abstract:

    This chapter describes two spatial Chemotaxis Assays, the nutrient-depleted Chemotaxis Assay and agarose-plug-bridge Assay, which enable the evaluation of putative chemoeffectors. These two Assays have worked well with Campylobacter jejuni and Helicobacter pylori, and techniques for using these Assays with these microbes are described.

  • a supplemented soft agar Chemotaxis Assay demonstrates the helicobacter pylori chemotactic response to zinc and nickel
    Microbiology, 2013
    Co-Authors: Lisa Sanders, Tessa M Andermann, Karen M. Ottemann
    Abstract:

    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.

  • the chemical in plug bacterial Chemotaxis Assay is prone to false positive responses
    BMC Research Notes, 2010
    Co-Authors: Mandy J Ward, Karen M. Ottemann
    Abstract:

    Background: Chemical-in-plug Assays are commonly used to study bacterial Chemotaxis, sometimes in the absence of stringent controls. Results: We report that non-chemotactic and non-motile mutants in two distinct bacterial species (Shewanella oneidensis and Helicobacter pylori) show apparent zones of accumulation or clearing around test plugs containing potential attractants or repellents, respectively. Conclusions: Our results suggest that the chemical-in-plug Assay should be used with caution, that non-motile or non-chemotactic mutants should be employed as controls, and that results should be confirmed with other types of Assays. Numerous spatial Assays, described below, are used to monitor bacterial Chemotaxis to particular chemicals. In these Assays, motile bacteria are first placed in a solution that does not contain the test chemical to be analyzed. Next, a high concentration of the test chemical is placed adjacent to the bacterial solution, and allowed to diffuse into it. If the bacteria respond chemotactically, they form either zones of concentrated bacteria or regions of clearing. One widely-used Chemotaxis Assay is the quantitative capillary Assay in which the test chemical is placed in a narrow-bore capillary, and the bacteria are in a surrounding solution [1]. In this Assay, chemotactic responses are measured by determining the number of bacteria that move into the capillary. This Assay works well for attractants, but not well for repellents as noted by Tso and Adler [2]. These authors first proposed the chemical-in-plug Assay, which is now often called the plug-in-pond Assay, as a way of studying the effect of repellent stimuli on bacterial behavior. This quick and simple Assay places a potential chemoeffector in an agar plug and surrounds the plug with a turbid suspension of bacteria in soft agar. Because the bacteria can swim in

  • the chemical in plug bacterial Chemotaxis Assay is prone to false positive responses bmc research notes 2010 3 77
    Journal Name: BMC Research Notes; Journal Volume: 3, 2010
    Co-Authors: Mandy J Ward, Karen M. Ottemann
    Abstract:

    Chemical-in-plug Assays are commonly used to study bacterial Chemotaxis, sometimes in the absence of stringent controls. We report that non-chemotactic and non-motile mutants in two distinct bacterial species (Shewanella oneidensis and Helicobacter pylori) show apparent zones of accumulation or clearing around test plugs containing potential attractants or repellents, respectively. Our results suggest that the chemical-in-plug Assay should be used with caution, that non-motile or non-chemotactic mutants should be employed as controls, and that results should be confirmed with other types of Assays.

Bennett S Lambert - One of the best experts on this subject based on the ideXlab platform.

  • a microfluidics based in situ Chemotaxis Assay to study the behaviour of aquatic microbial communities
    Nature microbiology, 2017
    Co-Authors: Bennett S Lambert, Jeanbaptiste Raina, Vicente Fernandez, Christian Rinke, Nachshon Siboni, Francesco Rubino, Philip Hugenholtz
    Abstract:

    Microbial interactions influence the productivity and biogeochemistry of the ocean, yet they occur in miniscule volumes that cannot be sampled by traditional oceanographic techniques. To investigate the behaviours of marine microorganisms at spatially relevant scales, we engineered an in situ Chemotaxis Assay (ISCA) based on microfluidic technology. Here, we describe the fabrication, testing and first field results of the ISCA, demonstrating its value in accessing the microbial behaviours that shape marine ecosystems.

Hirotaka Hida - One of the best experts on this subject based on the ideXlab platform.

  • Chemotaxis Assay of plant parasitic nematodes on a gel filled microchannel device
    Sensors and Actuators B-chemical, 2015
    Co-Authors: Hirotaka Hida, Hidetaka Nishiyama, Shinichiro Sawa, Tetsuya Higashiyama, Hideyuki Arata
    Abstract:

    Abstract Plant-parasitic nematodes substantially damage a wide variety of agricultural crops worldwide. The Chemotaxis of nematodes is a key factor in their parasitic relationship with plants. Therefore, studies on nematode Chemotaxis are essential for devising efficient and environmentally friendly management methods. In this paper, we report a new, efficient, and quantitative method to analyze Chemotaxis of the plant-parasitic nematode, Meloidogyne incognita , using a gel-filled microchannel device. We quantitatively defined time-dependent concentration gradients of chemicals in the gel-filled microchannel by measuring changes in the fluorescence intensity of fluorescein. We also developed a protocol to allow the nematodes to move around in the microchannels by loading an agarose gel with optimum concentration. Using this novel Assay method, we have shown that potassium nitrate (KNO 3 ) stimulates the behavior of M. incognita and can have both repellent and attractant effects, depending on the concentration gradient. This newly developed quantitative Chemotaxis Assay method can be used to screen and identify new candidate molecules that repel or attract nematodes, and also to analyze the repellent/attractant properties of those molecules toward nematodes.

  • high throughput Chemotaxis Assay of plant parasitic nematode toward green agriculture
    18th International Conference on Miniaturized Systems for Chemistry and Life Sciences MicroTAS 2014, 2014
    Co-Authors: Hirotaka Hida, M Matsumura, Isaku Kanno, Hidetaka Nishiyama, Shinichiro Sawa, Tetsuya Higashiyama, Hideyuki Arata
    Abstract:

    This paper presents a new microsystem for simple and high-throughput Chemotaxis Assay of plantparasitic nematodes Meloidogyne incognita. To improve an efficiency of Chemotaxis Assay, we developed a PDMS (Polydimethylsiloxane) microsystem, which can generate various chemical conditions in multiple microchannels at once. By using this system, we successfully identified a lower limitation of the concentration gradient of KNO3 solution, which can act as a repellent for the nematode M. incognita.

  • on chip Chemotaxis Assay of plant parasitic nematode towards increasing global crop productivity
    17th International Conference on Miniaturized Systems for Chemistry and Life Sciences MicroTAS 2013, 2013
    Co-Authors: Hirotaka Hida, Hidetaka Nishiyama, Shinichiro Sawa, Tetsuya Higashiyama, Hideyuki Arata
    Abstract:

    This paper reports a new method for simple and efficient on-chip Chemotaxis Assay of plant-parasitic nematode, Meloidogyne incognita. To precisely characterize Chemotaxis of the nematodes, we have developed a polydimethylsiloxane (PDMS) T-shaped microchannel-device which has a pair of micro-slits connected by narrow microchannel arrays with chemical inlets. This microchannel-device can efficiently create controllable chemical conditions for analyzing nematodes behavior. We have established a protocol to allow nematodes to swim freely in the microchannel by loading an agarose gel. Then, KNO3 was firstly identified as attractant/repellent and the nematode behavior depending on chemical conditions was quantitatively investigated. This method might contribute to global food and energy problems by improving crop productivity.

David G Alleva - One of the best experts on this subject based on the ideXlab platform.

  • a high throughput Chemotaxis Assay for pharmacological characterization of chemokine receptors utilization of u937 monocytic cells
    Journal of Pharmacological and Toxicological Methods, 2005
    Co-Authors: Thomas R Ott, Anil Pahuja, Francisco M Lio, Monica S Mistry, Molly M Gross, Sarah Hudson, Warren Wade, Pedro B Simpson, Scott R Struthers, David G Alleva
    Abstract:

    Introduction: Higher-throughput Chemotaxis Assays have had limited use in chemokine receptor pharmacology studies mainly because of the unavailability of optimal Assay formats in addition to an incompatibility of chemotactic cell backgrounds with other pharmacological Assays. Here, we developed a high-throughput 96-well Chemotaxis Assay for leukocytic cell lines and identified the human U937 monocytic line as an excellent cell background for both Chemotaxis and the high-throughput calcium mobilization Fluorescent Imaging Plate Reader (FLIPR) Assay. Methods: Optimal chemotactic conditions were developed using the Neuroprobe MBA96 nondisposable and the Millipore MultiScreen-MIC disposable apparatuses with responses to CXC chemokine receptor (CXCR)-4 endogenously expressed on the human H9 T lymphoma line, and confirmed with Jurkat T cell and U937 monocytic cell lines. Results: The U937 cell line was chosen for site-directed mutagenesis studies with CC chemokine receptor (CCR)-7 because this cell line did not endogenously express this receptor, it demonstrated a good Chemotaxis index, and it showed an exceptional ability to mobilize calcium measured via FLIPR. Using the Millipore MultiScreen-MIC and FLIPR Assays, alanine substitutions at K130 and Q227 caused threefold shifts in potency for the CCR7 ligand, CCL19, whereas that at K137 had no effect. Discussion: Because these CCR7 mutations have previously been shown not to affect ligand binding, our results here show that these residues are specifically involved in receptor activation signals critical to Chemotaxis and underscore the importance of using the U937 cell background to confirm results of Chemotaxis with those of the FLIPR Assay.