Chemotaxis: The movement of cells or organisms toward or away from a substance in response to its concentration gradient.Chemotaxis, Leukocyte: The movement of leukocytes in response to a chemical concentration gradient or to products formed in an immunologic reaction.Chemotactic Factors: Chemical substances that attract or repel cells. The concept denotes especially those factors released as a result of tissue injury, microbial invasion, or immunologic activity, that attract LEUKOCYTES; MACROPHAGES; or other cells to the site of infection or insult.Neutrophils: Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.Dictyostelium: A genus of protozoa, formerly also considered a fungus. Its natural habitat is decaying forest leaves, where it feeds on bacteria. D. discoideum is the best-known species and is widely used in biomedical research.N-Formylmethionine Leucyl-Phenylalanine: A formylated tripeptide originally isolated from bacterial filtrates that is positively chemotactic to polymorphonuclear leucocytes, and causes them to release lysosomal enzymes and become metabolically activated.Cell Movement: The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Chemokine CXCL12: A CXC chemokine that is chemotactic for T-LYMPHOCYTES and MONOCYTES. It has specificity for CXCR4 RECEPTORS. Two isoforms of CXCL12 are produced by alternative mRNA splicing.Bacterial Proteins: Proteins found in any species of bacterium.Chemokines, CXC: Group of chemokines with paired cysteines separated by a different amino acid. CXC chemokines are chemoattractants for neutrophils but not monocytes.Receptors, Formyl Peptide: A family of G-protein-coupled receptors that was originally identified by its ability to bind N-formyl peptides such as N-FORMYLMETHIONINE LEUCYL-PHENYLALANINE. Since N-formyl peptides are found in MITOCHONDRIA and BACTERIA, this class of receptors is believed to play a role in mediating cellular responses to cellular damage and bacterial invasion. However, non-formylated peptide ligands have also been found for this receptor class.Complement C5a: The minor fragment formed when C5 convertase cleaves C5 into C5a and COMPLEMENT C5B. C5a is a 74-amino-acid glycopeptide with a carboxy-terminal ARGININE that is crucial for its spasmogenic activity. Of all the complement-derived anaphylatoxins, C5a is the most potent in mediating immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE), smooth MUSCLE CONTRACTION; HISTAMINE RELEASE; and migration of LEUKOCYTES to site of INFLAMMATION.Receptors, Chemokine: Cell surface glycoproteins that bind to chemokines and thus mediate the migration of pro-inflammatory molecules. The receptors are members of the seven-transmembrane G protein-coupled receptor family. Like the CHEMOKINES themselves, the receptors can be divided into at least three structural branches: CR, CCR, and CXCR, according to variations in a shared cysteine motif.Receptors, Interleukin-8B: High-affinity G-protein-coupled receptors for INTERLEUKIN-8 present on NEUTROPHILS; MONOCYTES; and T-LYMPHOCYTES. These receptors also bind several other CXC CHEMOKINES.Flagella: A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called FLAGELLIN. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as CILIA but are longer in proportion to the cell bearing them and present in much smaller numbers. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Cell Migration Inhibition: Phenomenon of cell-mediated immunity measured by in vitro inhibition of the migration or phagocytosis of antigen-stimulated LEUKOCYTES or MACROPHAGES. Specific CELL MIGRATION ASSAYS have been developed to estimate levels of migration inhibitory factors, immune reactivity against tumor-associated antigens, and immunosuppressive effects of infectious microorganisms.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Receptors, Interleukin-8A: High-affinity G-protein-coupled receptors for INTERLEUKIN-8 present on NEUTROPHILS; MONOCYTES; and BASOPHILS.Bacterial Physiological Phenomena: Physiological processes and properties of BACTERIA.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Monocytes: Large, phagocytic mononuclear leukocytes produced in the vertebrate BONE MARROW and released into the BLOOD; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Interleukin-8: A member of the CXC chemokine family that plays a role in the regulation of the acute inflammatory response. It is secreted by variety of cell types and induces CHEMOTAXIS of NEUTROPHILS and other inflammatory cells.Receptors, CXCR4: CXCR receptors with specificity for CXCL12 CHEMOKINE. The receptors may play a role in HEMATOPOIESIS regulation and can also function as coreceptors for the HUMAN IMMUNODEFICIENCY VIRUS.Chemoreceptor Cells: Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.Pseudopodia: A dynamic actin-rich extension of the surface of an animal cell used for locomotion or prehension of food.Receptors, Amino Acid: Cell surface proteins that bind amino acids and trigger changes which influence the behavior of cells. Glutamate receptors are the most common receptors for fast excitatory synaptic transmission in the vertebrate central nervous system, and GAMMA-AMINOBUTYRIC ACID and glycine receptors are the most common receptors for fast inhibition.Chemokines, CC: Group of chemokines with adjacent cysteines that are chemoattractants for lymphocytes, monocytes, eosinophils, basophils but not neutrophils.Leukotriene B4: The major metabolite in neutrophil polymorphonuclear leukocytes. It stimulates polymorphonuclear cell function (degranulation, formation of oxygen-centered free radicals, arachidonic acid release, and metabolism). (From Dictionary of Prostaglandins and Related Compounds, 1990)Chemokines: Class of pro-inflammatory cytokines that have the ability to attract and activate leukocytes. They can be divided into at least three structural branches: C; (CHEMOKINES, C); CC; (CHEMOKINES, CC); and CXC; (CHEMOKINES, CXC); according to variations in a shared cysteine motif.Actins: Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.Chemokine CCL2: A chemokine that is a chemoattractant for MONOCYTES and may also cause cellular activation of specific functions related to host defense. It is produced by LEUKOCYTES of both monocyte and lymphocyte lineage and by FIBROBLASTS during tissue injury. It has specificity for CCR2 RECEPTORS.Cell Adhesion: Adherence of cells to surfaces or to other cells.Cell Polarity: Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.Methylation: Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed)N-Formylmethionine: Effective in the initiation of protein synthesis. The initiating methionine residue enters the ribosome as N-formylmethionyl tRNA. This process occurs in Escherichia coli and other bacteria as well as in the mitochondria of eucaryotic cells.Receptors, CCR2: CCR receptors with specificity for CHEMOKINE CCL2 and several other CCL2-related chemokines. They are expressed at high levels in T-LYMPHOCYTES; B-LYMPHOCYTES; MACROPHAGES; BASOPHILS; and NK CELLS.Chemokine CCL19: A CC-type chemokine with specificity for CCR7 RECEPTORS. It has activity towards T LYMPHOCYTES and B LYMPHOCYTES.Phosphatidylinositol 3-Kinases: Phosphotransferases that catalyzes the conversion of 1-phosphatidylinositol to 1-phosphatidylinositol 3-phosphate. Many members of this enzyme class are involved in RECEPTOR MEDIATED SIGNAL TRANSDUCTION and regulation of vesicular transport with the cell. Phosphatidylinositol 3-Kinases have been classified both according to their substrate specificity and their mode of action within the cell.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Receptors, CCR1: CCR receptors with specificity for a broad variety of CC CHEMOKINES. They are expressed at high levels in MONOCYTES; tissue MACROPHAGES; NEUTROPHILS; and EOSINOPHILS.Cell Migration Assays, Leukocyte: Assays that measure the rate of migration of LEUKOCYTES. They may involve a variety of techniques such as measuring the movement of leukocytes through substrates such as AGAROSE gels or the rate of exit of cells from a glass capillary.rac GTP-Binding Proteins: A sub-family of RHO GTP-BINDING PROTEINS that is involved in regulating the organization of cytoskeletal filaments. This enzyme was formerly listed as EC 3.6.1.47.Chemokine CCL5: A CC-type chemokine that is a chemoattractant for EOSINOPHILS; MONOCYTES; and LYMPHOCYTES. It is a potent and selective eosinophil chemotaxin that is stored in and released from PLATELETS and activated T-LYMPHOCYTES. Chemokine CCL5 is specific for CCR1 RECEPTORS; CCR3 RECEPTORS; and CCR5 RECEPTORS. The acronym RANTES refers to Regulated on Activation, Normal T Expressed and Secreted.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Cyclic AMP: An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.Neutrophil Activation: The process in which the neutrophil is stimulated by diverse substances, resulting in degranulation and/or generation of reactive oxygen products, and culminating in the destruction of invading pathogens. The stimulatory substances, including opsonized particles, immune complexes, and chemotactic factors, bind to specific cell-surface receptors on the neutrophil.Complement C5: C5 plays a central role in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C5 is cleaved by C5 CONVERTASE into COMPLEMENT C5A and COMPLEMENT C5B. The smaller fragment C5a is an ANAPHYLATOXIN and mediator of inflammatory process. The major fragment C5b binds to the membrane initiating the spontaneous assembly of the late complement components, C5-C9, into the MEMBRANE ATTACK COMPLEX.Phagocytosis: The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).Eosinophils: Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin.Receptors, CXCR3: CXCR receptors that are expressed on the surface of a number of cell types, including T-LYMPHOCYTES; NK CELLS; DENDRITIC CELLS; and a subset of B-LYMPHOCYTES. The receptors are activated by CHEMOKINE CXCL9; CHEMOKINE CXCL10; and CHEMOKINE CXCL11.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Receptors, Lipoxin: Cell surface proteins that bind LIPOXINS with high affinity and trigger intracellular changes influencing the behavior of cells.HL-60 Cells: A promyelocytic cell line derived from a patient with ACUTE PROMYELOCYTIC LEUKEMIA. HL-60 cells lack specific markers for LYMPHOID CELLS but express surface receptors for FC FRAGMENTS and COMPLEMENT SYSTEM PROTEINS. They also exhibit phagocytic activity and responsiveness to chemotactic stimuli. (From Hay et al., American Type Culture Collection, 7th ed, pp127-8)Chemokine CCL7: A monocyte chemoattractant protein that has activity towards a broad variety of immune cell types. Chemokine CCL7 has specificity for CCR1 RECEPTORS; CCR2 RECEPTORS; and CCR5 RECEPTORS.Azospirillum brasilense: A species of motile, free-living, gram-negative bacteria that occur in the soil. They are aerobic or microaerophilic and are sometimes capable of nitrogen fixation.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Spirochaeta: A genus of flexible, spiral rods found in hydrogen sulfide-containing mud, sewage, and polluted water. None of the species properly referred to in this genus are pathogenic.Receptors, Cell Surface: Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.Chemokine CCL21: A CC-type chemokine with specificity for CCR7 RECEPTORS. It has activity towards DENDRITIC CELLS and T-LYMPHOCYTES.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Macrophage Inflammatory Proteins: Heparin-binding proteins that exhibit a number of inflammatory and immunoregulatory activities. Originally identified as secretory products of MACROPHAGES, these chemokines are produced by a variety of cell types including NEUTROPHILS; FIBROBLASTS; and EPITHELIAL CELLS. They likely play a significant role in respiratory tract defenses.ZymosanPertussis Toxin: One of the virulence factors produced by BORDETELLA PERTUSSIS. It is a multimeric protein composed of five subunits S1 - S5. S1 contains mono ADPribose transferase activity.Salmonella typhimurium: A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.Receptors, CCR3: CCR receptors with specificity for CHEMOKINE CCL11 and a variety of other CC CHEMOKINES. They are expressed at high levels in T-LYMPHOCYTES; EOSINOPHILS; BASOPHILS; and MAST CELLS.Receptors, CCR7: CCR receptors with specificity for CHEMOKINE CCL19 and CHEMOKINE CCL21. They are expressed at high levels in T-LYMPHOCYTES; B-LYMPHOCYTES; and DENDRITIC CELLS.Microfluidic Analytical Techniques: Methods utilizing the principles of MICROFLUIDICS for sample handling, reagent mixing, and separation and detection of specific components in fluids.Leukocytes: White blood cells. These include granular leukocytes (BASOPHILS; EOSINOPHILS; and NEUTROPHILS) as well as non-granular leukocytes (LYMPHOCYTES and MONOCYTES).Macrophages: The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)Monocyte Chemoattractant Proteins: Chemokines that are chemoattractants for monocytes. These CC chemokines (cysteines adjacent) number at least three including CHEMOKINE CCL2.Phosphatidylinositol Phosphates: Phosphatidylinositols in which one or more alcohol group of the inositol has been substituted with a phosphate group.Microscopy, Video: Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in TELEPATHOLOGY.Mice, Inbred C57BLPlatelet-Derived Growth Factor: Mitogenic peptide growth hormone carried in the alpha-granules of platelets. It is released when platelets adhere to traumatized tissues. Connective tissue cells near the traumatized region respond by initiating the process of replication.Receptors, Leukotriene B4: A class of cell surface leukotriene receptors with a preference for leukotriene B4. Leukotriene B4 receptor activation influences chemotaxis, chemokinesis, adherence, enzyme release, oxidative bursts, and degranulation in polymorphonuclear leukocytes. There are at least two subtypes of these receptors. Some actions are mediated through the inositol phosphate and diacylglycerol second messenger systems.Receptors, G-Protein-Coupled: The largest family of cell surface receptors involved in SIGNAL TRANSDUCTION. They share a common structure and signal through HETEROTRIMERIC G-PROTEINS.Chemokine CXCL1: A CXC chemokine with specificity for CXCR2 RECEPTORS. It has growth factor activities and is implicated as a oncogenic factor in several tumor types.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Chemokine CCL4: A CC chemokine with specificity for CCR5 RECEPTORS. It is a chemoattractant for NK CELLS; MONOCYTES and a variety of other immune cells. This chemokine is encoded by multiple genes.Receptor, Anaphylatoxin C5a: A G-protein-coupled receptor that signals an increase in intracellular calcium in response to the potent ANAPHYLATOXIN peptide COMPLEMENT C5A.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Chemokine CX3CL1: A CX3C chemokine that is a transmembrane protein found on the surface of cells. The soluble form of chemokine CX3CL1 can be released from cell surface by proteolysis and act as a chemoattractant that may be involved in the extravasation of leukocytes into inflamed tissues. The membrane form of the protein may also play a role in cell adhesion.Cytoskeleton: The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.Ligands: A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)Microfluidics: The study of fluid channels and chambers of tiny dimensions of tens to hundreds of micrometers and volumes of nanoliters or picoliters. This is of interest in biological MICROCIRCULATION and used in MICROCHEMISTRY and INVESTIGATIVE TECHNIQUES.Class Ib Phosphatidylinositol 3-Kinase: A phosphatidylinositol 3-kinase subclass that includes enzymes formed through the association of a p110gamma catalytic subunit and one of the three regulatory subunits of 84, 87, and 101 kDa in size. This subclass of enzymes is a downstream target of G PROTEIN-COUPLED RECEPTORS.Kinetics: The rate dynamics in chemical or physical systems.Lysophospholipids: Derivatives of PHOSPHATIDIC ACIDS that lack one of its fatty acyl chains due to its hydrolytic removal.Methyltransferases: A subclass of enzymes of the transferase class that catalyze the transfer of a methyl group from one compound to another. (Dorland, 28th ed) EC 2.1.1.Chemokine CCL11: A CC-type chemokine that is specific for CCR3 RECEPTORS. It is a potent chemoattractant for EOSINOPHILS.Enzyme Activation: Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.Disposable Equipment: Apparatus, devices, or supplies intended for one-time or temporary use.Chromium Alloys: Specific alloys not less than 85% chromium and nickel or cobalt, with traces of either nickel or cobalt, molybdenum, and other substances. They are used in partial dentures, orthopedic implants, etc.Biochemistry: The study of the composition, chemical structures, and chemical reactions of living things.Receptors, Atrial Natriuretic Factor: Cell surface proteins that bind ATRIAL NATRIURETIC FACTOR with high affinity and trigger intracellular changes influencing the behavior of cells. They contain intrinsic guanylyl cyclase activity.JapanRepublic of Korea: The capital is Seoul. The country, established September 9, 1948, is located on the southern part of the Korean Peninsula. Its northern border is shared with the Democratic People's Republic of Korea.

Cell polarization: chemotaxis gets CRACKing. (1/5128)

An early stage in the establishment of cell polarity during chemotaxis of Dictyostelium dicoideum has been identified by a recent study; the new results also show that the development of cell polarity does not rely upon cytoskeletal rearrangement, and may use a spatial sensing mechanism.  (+info)

Tyrosine phosphorylation is required for actin-based motility of vaccinia but not Listeria or Shigella. (2/5128)

Studies of the actin-based motility of pathogens have provided important insights into the events occurring at the leading edge of motile cells [1] [2] [3]. To date, several actin-cytoskeleton-associated proteins have been implicated in the motility of Listeria or Shigella: vasodilator-stimulated phosphoprotein (VASP), vinculin and the actin-related protein complex of Arp2 and Arp3 [4] [5] [6] [7]. To further investigate the underlying mechanism of actin-tail assembly, we examined the localization of components of the actin cytoskeleton including Arp3, VASP, vinculin and zyxin during vaccinia, Listeria and Shigella infections. The most striking difference between the systems was that a phosphotyrosine signal was observed only at the site of vaccinia actin-tail assembly. Micro-injection experiments demonstrated that a phosphotyrosine protein plays an important role in vaccinia actin-tail formation. In addition, we observed a phosphotyrosine signal on clathrin-coated vesicles that have associated actin-tail-like structures and on endogenous vesicles in Xenopus egg extracts which are able to nucleate actin tails [8] [9]. Our observations indicate that a host phosphotyrosine protein is required for the nucleation of actin filaments by vaccinia and suggest that this phosphoprotein might be associated with cellular membranes that can nucleate actin.  (+info)

Role of thrombin receptor in breast cancer invasiveness. (3/5128)

Invasion, the ability of an epithelial cancer cell to detach from and move through a basement membrane, is a central process in tumour metastasis. Two components of invasion are proteolysis of extracellular matrix and cellular movement through it. A potential promoter of these two processes is thrombin, the serine proteinase derived from the ubiquitous plasma protein prothrombin. Thrombin promotes the invasion of MDA-MB231 breast tumour cells (a highly aggressive cell line) in an in vitro assay. Invasion by MDA-MB436 and MCF-7 cells, less aggressive cell lines, is not promoted by thrombin. Thrombin, added to the cells, is a stimulator of cellular movement; fibroblast-conditioned medium is the chemotaxin. Thrombin-promoted invasion is inhibited by hirudin. Stimulation of invasion is a receptor-mediated process that is mimicked by a thrombin receptor-activating peptide. Thrombin has no effect on chemotaxis in vitro. Thrombin receptor is detectable on the surface of MDA-MB231 cells, but not on the other two cell lines. Introduction of oestrogen receptors into MDA-MB231 cells by transfection with pHEO had no effect on thrombin receptor expression, in the presence or absence of oestradiol. This paper demonstrates that thrombin increases invasion by the aggressive breast cancer cell line MDA-MB231 by a thrombin receptor-dependent mechanism.  (+info)

Similarities and differences in RANTES- and (AOP)-RANTES-triggered signals: implications for chemotaxis. (4/5128)

Chemokines are a family of proinflammatory cytokines that attract and activate specific types of leukocytes. Chemokines mediate their effects via interaction with seven transmembrane G protein-coupled receptors (GPCR). Using CCR5-transfected HEK-293 cells, we show that both the CCR5 ligand, RANTES, as well as its derivative, aminooxypentane (AOP)- RANTES, trigger immediate responses such as Ca2+ influx, receptor dimerization, tyrosine phosphorylation, and Galphai as well as JAK/STAT association to the receptor. In contrast to RANTES, (AOP)-RANTES is unable to trigger late responses, as measured by the association of focal adhesion kinase (FAK) to the chemokine receptor complex, impaired cell polarization required for migration, or chemotaxis. The results are discussed in the context of the dissociation of the late signals, provoked by the chemokines required for cell migration, from early signals.  (+info)

Chemotactic responses of Escherichia coli to small jumps of photoreleased L-aspartate. (5/5128)

Computer-assisted motion analysis coupled to flash photolysis of caged chemoeffectors provides a means for time-resolved analysis of bacterial chemotaxis. Escherichia coli taxis toward the amino acid attractant L-aspartate is mediated by the Tar receptor. The physiology of this response, as well as Tar structure and biochemistry, has been studied extensively. The beta-2, 6-dinitrobenzyl ester of L-aspartic acid and the 1-(2-nitrophenyl)ethyl ether of 8-hydroxypyrene-1,3,6-tris-sulfonic acid were synthesized. These compounds liberated L-aspartate and the fluorophore 8-hydroxypyrene 1,3,6-tris-sulfonic acid (pyranine) upon irradiation with near-UV light. Photorelease of the fluorophore was used to define the amplitude and temporal stability of the aspartate jumps employed in chemotaxis experiments. The dependence of chemotactic adaptation times on aspartate concentration, determined in mixing experiments, was best fit by two Tar aspartate-binding sites. Signal processing (excitation) times, amplitudes, and adaptive recovery of responses elicited by aspartate jumps producing less than 20% change in receptor occupancy were characterized in photorelease assays. Aspartate concentration jumps in the nanomolar range elicited measurable responses. The response threshold and sensitivity of swimming bacteria matched those of bacteria tethered to glass by a single flagellum. Stimuli of similar magnitude, delivered either by rapid mixing or photorelease, evoked responses of similar strength, as assessed by recovery time measurements. These times remained proportional to change in receptor occupancy close to threshold, irrespective of prior occupancy. Motor excitation responses decayed exponentially with time. Rates of excitation responses near threshold ranged from 2 to 7 s-1. These values are consistent with control of excitation signaling by decay of phosphorylated pools of the response regulator protein, CheY. Excitation response rates increased slightly with stimulus size up to values limited by the instrumentation; the most rapid was measured to be 16 +/- 3 (SE) s-1. This increase may reflect simultaneous activation of CheY dephosphorylation, together with inhibition of its phosphorylation.  (+info)

Tn5-induced and spontaneous switching of Sinorhizobium meliloti to faster-swarming behavior. (6/5128)

Tn5 mutants of Sinorhizobium meliloti RMB7201 which swarmed 1.5 to 2. 5 times faster than the parental strain in semisolid agar, moist sand, and viscous liquid were identified. These faster-swarming (FS) mutants outgrew the wild type 30- to 40-fold within 2 days in mixed swarm colonies. The FS mutants survived and grew as well as or better than the wild type under all of the circumstances tested, except in a soil matrix subjected to air drying. Exopolysaccharide (EPS) synthesis was reduced in each of the FS mutants when they were grown on defined succinate-nitrate medium, but the extent of reduction was different for each. It appears that FS behavior likely results from a modest, general derepression of motility involving an increased proportion of motile and flagellated cells and an increased average number of flagella per cell and increased average flagellar length. Spontaneous FS variants of RMB7201 were obtained at a frequency of about 1 per 10,000 to 20,000 cells by either enrichment from the periphery of swarm colonies or screening of colonies for reduced EPS synthesis on succinate-nitrate plates. The spontaneous FS variants and Tn5 FS mutants were symbiotically effective and competitive in alfalfa nodulation. Reversion of FS variants to wild-type behavior was sporadic, indicating that reversion is affected by unidentified environmental factors. Based on phenotypic and molecular differences between individual FS variants and mutants, it appears that there may be multiple genetic configurations that result in FS behavior in RMB7201. The facile isolation of spontaneous FS variants of Escherichia coli and Pseudomonas aeruginosa indicates that switching to FS behavior may be fairly common among bacterial species. The substantial growth advantage of FS mutants and variants wherever nutrient gradients exist suggests that switching to FS forms may be an important behavioral adaptation in natural environments.  (+info)

Sperm chemotaxis. (7/5128)

Communication between spermatozoa and egg before contact by chemotaxis appears to be prevalent throughout the animal kingdom. In non-mammalian species, sperm chemotaxis to factors secreted from the egg is well documented. In mammals, sperm chemotaxis to follicular factors in vitro has been established in humans and mice. The attractants of female origin in non-mammalian species are heat-stable peptides or proteins of various sizes, or other small molecules, depending on the species. Species specificity of the attractants in non-mammalian species may vary from high species specificity, through specificity to families with no specificity within a family, to absence of specificity. The mammalian sperm attractants have not been identified but they appear to be heat-stable peptides. The claim that progesterone is the attractant for human spermatozoa has failed to be substantiated, neither have claims for other mammalian sperm attractants been verified. The molecular mechanism of sperm chemotaxis is not known. Models involving modulation of the intracellular Ca2+ concentration have been proposed for both mammalian and non-mammalian sperm chemotaxis. The physiological role of sperm chemotaxis in non-mammalian species appears to differ from that in mammals. In non-mammalian species, sperm chemotaxis strives to bring as many spermatozoa as possible to the egg. However, in mammals, the role appears to be recruitment of a selective population of capacitated ('ripe') spermatozoa to fertilize the egg.  (+info)

Cloning and characterization of chemotaxis genes in Pseudomonas aeruginosa. (8/5128)

Two chemotaxis-defective mutants of Pseudomonas aeruginosa, designated PC3 and PC4, were selected by the swarm plate method after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. These mutants were not complemented by the P. aeruginosa cheY and cheZ genes, which had been previously cloned (Masduki et al., J. Bacteriol., 177, 948-952, 1995). DNA sequences downstream of the cheY and cheZ genes were able to complement PC3 but not PC4. Sequence analysis of a 9.7-kb region directly downstream of the cheZ gene found three chemotaxis genes, cheA, cheB, and cheW, and seven unknown open reading frames (ORFs). The predicted translation products of the cheA, cheB, and cheW genes showed 33, 36, and 31% amino acid identity with Escherichia coli CheA, CheB, and CheW, respectively. Two of the unknown ORFs, ORF1 and ORF2, encoded putative polypeptides that resembled Bacillus subtilis MotA (40% amino acid identity) and MotB (34% amino acid identity) proteins, respectively. Although P. aeruginosa was found to have proteins similar to the enteric chemotaxis proteins CheA, CheB, CheW, CheY, and CheZ, the gene encoding a CheR homologue did not reside in the chemotaxis gene cluster. The P. aeruginosa cheR gene could be cloned by phenotypic complementation of the PC4 mutant. This gene was located at least 1,800 kb away from the chemotaxis gene cluster and encoded a putative polypeptide that had 32% amino acid identity with E. coli CheR.  (+info)

*Chemotaxis

... Neutrophil Chemotaxis Cell Migration Gateway Downloadable Matlab chemotaxis simulator Bacterial Chemotaxis ... Chemotaxis (from chemo- + taxis) is the movement of an organism in response to a chemical stimulus. Somatic cells, bacteria, ... Positive chemotaxis occurs if the movement is toward a higher concentration of the chemical in question; negative chemotaxis if ... 1911). "Chemotaxis". Encyclopædia Britannica. 6 (11th ed.). Cambridge University Press. p. 77. Chemotaxis Lecture. Uploaded in ...

*Chemotaxis assay

Chemotaxis Cell Migration Gateway Cytometric chemotaxis and cell migration assay Free tool based on ImageJ to analyse ... Chemotaxis assays are experimental tools for evaluation of chemotactic ability of prokaryotic or eukaryotic cells. A wide ... Zicha D.; Dunn G.A.; Brown A.F. (1991). "A new direct-viewing chemotaxis chamber". J Cell Sci. 99: 769-75. PMID 1770004. Leick ... Seymour J. R.; J. R. Ahmed; Marcos S. R (2008). "A microfluidic chemotaxis assay to study microbial behavior in diffusing ...

*Sperm chemotaxis

Eisenbach, M. (2004) Chemotaxis. Imperial College Press, London. Miller, R.L. (1997) Specificity of sperm chemotaxis among ... In some species (for example, herring or the ascidian Ciona) activation of motility precedes chemotaxis. In chemotaxis, cells ... chemotaxis was substantiated as the cause of this accumulation. Sperm chemotaxis was later also demonstrated in mice and ... sperm guidance in the form of sperm chemotaxis has been established in a large variety of species Although sperm chemotaxis is ...

*Methyl-accepting chemotaxis protein

... (MCP) is a transmembrane sensor protein of bacteria. Use of the MCP allows bacteria to ...

*Chemokinesis

However, in contrast to chemotaxis, chemokinesis has a random, non-vectorial moiety, in general. Due to the random character, ... Becker EL (1977). "Stimulated neutrophil locomotion: chemokinesis and chemotaxis". Arch Pathol Lab Med. 101 (10): 509-13. PMID ... techniques dedicated to evaluate chemokinesis are partly different from methods used in chemotaxis research. One of the most ...

*Chemotactic selection

Chemotaxis receptors are expressed in the surface membrane with diverse dynamics, some of them have long-term characteristics ... Kohidai L and Csaba G (1988). "Chemotaxis and chemotactic selection induced with cytokines (IL-8, RANTES and TNF alpha) in the ... Recent results proved that chemokines (e.g. IL-8, RANTES) are working on long-term chemotaxis receptors, while vasoactive ... The diverse feature of the chemotaxis receptors and ligands provides the possibility to select chemotactic responder cells with ...

*MotA

Eisenbach M, Lengeler JW, Varon M; D. Gutnick D; Firtel FA, Omann GM, Tamada A, Murakami F (2004). Chemotaxis. River Edge, N.J ...

*MotB

Chemotaxis. River Edge, N.J: Imperial College Press. ISBN 1-86094-413-2. CS1 maint: Multiple names: authors list (link) ...

*Twitching motility

In contrast to the run-and-tumble model of chemotaxis associated with flagellated cells however, movement towards ... Oliveira, Nuno M.; Foster, Kevin R.; Durham, William M. (2016-06-07). "Single-cell twitching chemotaxis in developing biofilms ... Sampedro, Inmaculada; Parales, Rebecca E.; Krell, Tino; Hill, Jane E. (January 2015). "Pseudomonas chemotaxis". FEMS ... "Pseudomonas aeruginosa Twitching Motility-Mediated Chemotaxis towards Phospholipids and Fatty Acids: Specificity and Metabolic ...

*David B. Dusenbery

Chemotaxis in bacteria. Annu. Rev. Biochem. 44:341-356. Macnab, R. M. 1978. Motility and chemotaxis. In Escherichia coli and ... Dusenbery, D.B. (1998). Fitness landscapes for effects of shape on chemotaxis and other behaviors of bacteria. J. Bacteriol. ... The gradient-sensing mechanism in bacterial chemotaxis. Proc. Natl. Acad. Sci. U.S.A. 69: 2509 -2512. Adler, J. 1975. ... Mathematical modeling and quantitative characterization of bacterial motility and chemotaxis. In Modeling the Metabolic and ...

*Lee Segel

He is particularly known for his work in the spontaneous appearance of order in convection, slime molds and chemotaxis. Lee ... They also developed a model for chemotaxis. Hillen and Painter say of it: "its success ... a consequence of its intuitive ... doi:10.1016/0022-5193(71)90050-6. Hillen, T.; Painter, K.J. (Jan 2009). "A user's guide to PDE models for chemotaxis. Journal ... Keller, E. F.; Segel, L. A. (1971). "Model for chemotaxis". J Theor Biol. 30: 225-234. ...

*Microfluidics

Ahmed, T.; Shimizu, T.S.; Stocker, R. (2010). "Microfluidics for bacterial chemotaxis". Integrative Biology. 2: 604-629. doi: ... chemotaxis and the ability to evolve / develop resistance to antibiotics in small populations of microorganisms and in a short ...

*Immune system

... chemokines that promote chemotaxis; and interferons that have anti-viral effects, such as shutting down protein synthesis in ... chemokines that promote chemotaxis; and interferons that have anti-viral effects, such as shutting down protein synthesis in ... neutrophils migrate toward the site of inflammation in a process called chemotaxis, and are usually the first cells to arrive ...

*Necrotaxis

Chemotaxis towards an injured cell". Antibiot. Chemother. 19: 369-81. PMID 4463832. Hu CL, Barnes FS (1970). "A Theory of ... Necrotaxis embodies a special type of chemotaxis when the chemoattractant molecules are released from necrotic or apoptotic ... Debru C. (1993). "A particular form of chemotaxis: necrotaxis. An historical view". Blood Cells. 19 (1): 5-19. PMID 8400312. ...

*N-Formylmethionine-leucyl-phenylalanine

Leukocyte chemotaxis: Methodology, physiology, clinical implications. New York.: Raven Press. CS1 maint: Multiple names: ... I. Harris H (Jul 1954). "Role of chemotaxis in inflammation". Physiological Reviews. 34 (3): 529-62. PMID 13185754. Ward PA, ... FMLP proved the most potent in stimulating rabbit neutrophil chemotaxis. FMLP and a sampling of other, less potent, N-formyl ... release N-formyl-methionyl containing peptides with chemotactic activities that exactly mimic those of FMLP chemotaxis These ...

*Protein-glutamate methylesterase

Other names in common use include chemotaxis-specific methylesterase, methyl-accepting chemotaxis protein methyl-esterase, CheB ... CheB is involved in chemotaxis. CheB methylesterase is responsible for removing the methyl group from the gamma-glutamyl methyl ... Kehry MR, Doak TG, Dahlquist FW (1984). "Stimulus-induced changes in methylesterase activity during chemotaxis in Escherichia ... This enzyme participates in 3 metabolic pathways: two-component system - general, bacterial chemotaxis - general, and bacterial ...

*Clustering of self-propelled particles

Self-propelled enzyme motors and synthetic nanomotors also exhibit clustering effects in the form of chemotaxis. Chemotaxis is ... Schnitzer, Mark J. (1 October 1993). "Theory of continuum random walks and application to chemotaxis". Physical Review E. 48 (4 ... Hong, Yiying; Blackman, Nicole M. K.; Kopp, Nathaniel D.; Sen, Ayusman; Velegol, Darrell (26 October 2007). "Chemotaxis of ... Chemotaxis, and/or Diffusiophoresis within several reviews by leading researchers in the self-propelled particles and ...

*Bacteria

Lux R, Shi W (2004). "Chemotaxis-guided movements in bacteria". Crit Rev Oral Biol Med. 15 (4): 207-20. doi:10.1177/ ... Motile bacteria are attracted or repelled by certain stimuli in behaviours called taxes: these include chemotaxis, phototaxis, ... PATRIC, a Bioinformatics Resource Center for bacterial pathogens, funded by NIAID Bacterial Chemotaxis Interactive Simulator-A ... web-app that uses several simple algorithms to simulate bacterial chemotaxis. Cell-Cell Communication in Bacteria on-line ...

*Helicobacter pylori

H. pylori is able to sense the pH gradient in the mucus and move towards the less acidic region (chemotaxis). This also keeps ... In addition to using chemotaxis to avoid areas of low pH, H. pylori also neutralizes the acid in its environment by producing ... Rust M, Schweinitzer T, Josenhans C (2008). "Helicobacter Flagella, Motility and Chemotaxis". In Yamaoka Y. Helicobacter pylori ...

*Collective motion

... defined as chemotaxis. Chemotaxis has been observed in self-propelled Au-Pt nanorods, which diffuse towards the source of ... Chemotaxis provides a way of directing motion at the microscale and can be used for drug delivery, sensing, lab-on-a-chip ... Hong, Y., Blackmann, NMK., Kopp, ND., Sen, A., & Velegol, D. (2007). Chemotaxis of nonbiological colloidal rods. Physics Review ...

*Glossary of phytopathology

for colony forming unit) chemotaxis (syn. chemotropism) chemotherapy chlamydospore chlamydospore A chlamydospore is the thick- ...

*Parallel-plate flow chamber

Parallel plate flow chambers are widely used also for drug testing in the cellular chemotaxis assay and for novel targeted drug ... "Drug Testing in Cellular Chemotaxis Assays". Current Protocols in Pharmacology. Unit Number: UNIT 12.11. June, 2008. ...

*Helicobacter

2008). "Helicobacter Flagella, Motility and Chemotaxis". Helicobacter pylori: Molecular Genetics and Cellular Biology (Yamaoka ...
Several methods for detecting or measuring negative chemotaxis are described. Using these, we have surveyed a number of chemicals for their ability to repel Escherichia coli. Although most of the repellents are harmful compounds, harmfulness is neither necessary nor sufficient to make a compound a repellent. The repellents can be grouped into at least nine classes according to (i) competition experiments, (ii) mutants lacking certain of the negative taxes, and (iii) their chemical structure. The specificity of each class was studied. It is suggested that each class corresponds to a distinct chemoreceptor. Generally, non-chemotactic mutants lack both positive and negative chemotaxis, and l-methionine is required for both kinds of taxis. Repellents at very low concentrations are not attractants, and attractants at very high concentrations are not repellents. ...
Abstract The two-component based chemotaxis signal transduction system allows flagellated bacteria to sense their surrounding chemical environment and move towards more favorable conditions. The attractant signals can be sensed by transmembrane chemoreceptors, and then transmitted to the histidine kinase CheA. Once activated, CheA interacts with the response regulator CheY through phosphorelay, which causes a change in the rotation of the flagella. The direction of flagella rotation determines whether a cell swims straight or just tumbles. Cells also need adaptation to respond to a change in chemical concentrations, and return to their prestimulated level. Adaptation in the B. subtilis chemotaxis system is achieved by three coordinated systems: the methylation system, the CheC/CheD/CheY-p system and the CheV system. CheD, the previously identified receptor deamidase, was shown to be critical to the ability of B. subtilis to perform chemotaxis and is the main focus of this study. This study ...
Sensory adaptation by the chemotaxis system of Escherichia coli requires adjustments of the extent of methyl esterification of the chemotaxis receptor proteins. One mechanism utilized by E. coli to make such adjustments is to control the activity of CheB, the enzyme responsible for removing receptor methyl ester groups. Previous work has established the existence of a multicomponent signal transduction pathway that enables the chemotaxis receptor proteins to control the methylesterase activity in response to chemotactic stimuli. We isolated and characterized CheB mutants that do not respond normally to this control mechanism. In intact cells these CheB variants could not be activated in response to negative chemotaxis stimuli. Further characterization indicated that these CheB variants could not be phosphorylated by the chemotaxis protein kinase CheA. Disruption of the mechanism responsible for regulating methylesterase activity was also observed in cells carrying chromosomal deletions of either cheA or
Rhodobacter sphaeroides has multiple homologues of most of the Escherichia coli chemotaxis genes, organized in two major operons and other, unlinked, loci. These include cheA1 and cheW1 (che Op1) and cheA2, cheW2 and cheW3 (che Op2). We have deleted each of these cheA and cheW homologues in-frame and examined the chemosensory behaviour of these strains on swarm plates and in tethered cell assays. In addition, we have examined the effect of these deletions on the polar localization of the chemoreceptor McpG. In E. coli, deletion of either cheA or cheW results in a non-chemotactic phenotype, and these strains also show no receptor clustering. Here, we demonstrate that CheW2 and CheA2 are required for the normal localization of McpG and for normal chemotactic responses under both aerobic and photoheterotrophic conditions. Under aerobic conditions, deletion of cheW3 has no significant effect on McpG localization and only has an effect on chemotaxis to shallow gradients in swarm plates. Under
Specific glutamates in the methyl-accepting chemotaxis proteins (MCPs) of Escherichia coli are modified during sensory adaptation. Attractants that bind to MCPs are known to increase the rate of receptor modification, as with serine and the serine receptor (Tsr), which contributes to an increase in the steady-state (adapted) methylation level. However, MCPs form ternary complexes with two cytoplasmic signaling proteins, the kinase (CheA) and an adaptor protein (CheW), but their influences on receptor methylation are unknown. Here, the influence of CheW on the rate of Tsr methylation has been studied to identify contributions to the process of adaptation. Methyl group incorporation was measured in a series of membrane samples in which the Tsr molecules were engineered to have one available methyl-accepting glutamate residue (297, 304, 311 or 493). The relative rates at these sites (0.14, 0.05, 0.05 and 1, respectively) differed from those found previously for the aspartate receptor (Tar), which was in
antibody-antibodies.com is the marketplace for research antibodies. Find the right antibody for your research needs. CobB regulates Escherichia coli chemotaxis by deacetylating the response regulator CheY.
The bacterial chemotaxis receptors are transmembrane receptors with a simple signalling pathway which has elements relevant to the general understanding of signal recognition and transduction across membranes, how signals are relayed between molecules in a pathway, and how adaptation to a persistent signal is achieved. Bacterial chemotaxis receptors are composed of a ligand-binding domain, a transmembrane domain consisting of two helices TM1 and TM2, and a cytoplasmic domain. All known bacterial chemotaxis receptors have a highly conserved cytoplasmic domain, which unites signals from different ligand domains into a single signalling pathway to flagella motors. ...
Chemotaxis (from chemo- + taxis) is the movement of an organism in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food (e.g., glucose) by swimming toward the highest concentration of food molecules, or to flee from poisons (e.g., phenol). In multicellular organisms, chemotaxis is critical to early development (e.g., movement of sperm towards the egg during fertilization) and subsequent phases of development (e.g., migration of neurons or lymphocytes) as well as in normal function. In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. Positive chemotaxis occurs if the movement is toward a higher concentration of the chemical in question; negative chemotaxis if the movement is in the opposite direction. Chemically prompted kinesis (randomly directed or ...
Neutrophils play a critical role in host defense against invading pathogens. Chemotaxis, the directed migration of cells, allows neutrophil to seek out the sites of inflammation and infection. Neutrophil chemotaxis as well as other type of cell migration are considered as cycles composed of highly orchestrated steps. Recently the underlying signaling mechanisms of neutrophil chemotaxis are better understood with the studies in knockout mice and neutrophil-like cell lines: a number of signaling molecules in neutrophil chemotaxis have been identified, and a feedback loop-based model of "frontness" and "backness" pathways has been proposed to explain the establishment of neutrophil polarity and chemotaxis. However, the signaling mechanisms that control actin cytoskeleton reorganization and interaction between the cells and the substratum on which cells migrate are still not fully understood. In my first research project, we have identified a signaling pathway, mediated by non-receptor tyrosine ...
In this talk, I will first discuss several chemotaxis models includingthe classical Keller-Segel model.Chemotaxis is the phenomenon in which cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals (chemoattractants) in their environment. The mathematical models of chemotaxis are usually described by highly nonlinear time dependent systems of PDEs. Therefore, accurate and efficient numerical methods are very important for the validation and analysis of these systems. Furthermore, a common property of all existing chemotaxis systems is their ability to model a concentration phenomenon that mathematically results in solutions rapidly growing in small neighborhoods of concentration points/curves. The solutions may blow up or may exhibit a very singular, spiky behavior. In either case, capturing such solutions numerically is a challenging problem. In our work we propose a family of stable (even at times near blow up) and highly accurate ...
Shop Probable chemotaxis response regulator protein-glutamate methylesterase ELISA Kit, Recombinant Protein and Probable chemotaxis response regulator protein-glutamate methylesterase Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
APL-1 overexpression using either the apl-1 or the snb-1 promoter, but not the pan-neuronal rab-3 promoter, caused a diminished chemotaxis response to both sodium acetate and benzaldehyde. Similarly, a short heat shock during adulthood to induce ubiquitous APL-1 expression was sufficient to cause an impaired chemotaxis response. These results suggest that APL-1 expression in non-neuronal cells decreases or disrupts the chemotaxis response. For instance, apl-1 signaling may interfere with the feedback from downstream neurons or non-neuronal tissue to the sensory neurons. Strikingly, the chemotaxis impairments of these transgenic animals were fully or partially restored by decreased activity of daf-2 insulin-IGF-1 receptor, daf-7 TGFβ, or daf-12 NHR signaling. Hence, the effects of APL-1 levels on chemotaxis are unlikely to be due to disrupted neuronal structure or neurodegeneration, but rather to modulation of the insulin/IGF-1 and/or DAF-12 NHR signaling pathways. Similarly, disruption of apl-1 ...
The main finding of the current study is that effector CD8+ T cells in skin epithelium approach clusters of infected cells by subtle chemotaxis. This directed migration can be described as a small preference for movements toward the microlesion in an otherwise highly irregular trajectory, and in fact the T cells move away from the sites of infection almost as often as they move toward it.. The observed CXCR3-mediated attraction of T cells by clusters of infected cells implies the existence of a chemoattractant gradient, and the finding that the strength of T cell attraction correlates with lesion size is also consistent with this notion. If T cells are guided to sites of infection by a gradient, why is their migration pattern so erratic? One explanation is that T cell migration has to occur through a bed of tightly linked keratinocytes, thereby severely limiting the number of potential trajectories. This, however, does not seem to explain why T cells also frequently move away from the site of ...
p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.,/p> ,p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.,/p> ,p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).,/p> ,p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x,sup>64,/sup> + x,sup>4,/sup> + x,sup>3,/sup> + x + 1. The algorithm is described in the ISO 3309 standard. ,/p> ,p class="publication">Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.,br /> ,strong>Cyclic redundancy and other checksums,/strong>,br /> ,a href="http://www.nrbook.com/b/bookcpdf.php">Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993),/a>),/p> Checksum:i ...
p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.,/p> ,p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.,/p> ,p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).,/p> ,p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x,sup>64,/sup> + x,sup>4,/sup> + x,sup>3,/sup> + x + 1. The algorithm is described in the ISO 3309 standard. ,/p> ,p class="publication">Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.,br /> ,strong>Cyclic redundancy and other checksums,/strong>,br /> ,a href="http://www.nrbook.com/b/bookcpdf.php">Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993),/a>),/p> Checksum:i ...
UNLABELLED: Chemokines (CK) provide directional cues that mediate the recruitment of leukocytes to sites of inflammation. Broad-spectrum blockade of the CC-CK family, using the vaccinia virus 35K protein, has been shown to cause a potent reduction of systemic inflammation in models of atherosclerosis, vein graft disease and arthritis. We have used a cell membrane-targeted form of 35K, Mem35K, to probe whether cell-associated blockade of chemokine response is sufficient to reduce cell recruitment in inflammation. In Tie2cre mice, activation of a flox-stop Mem35K transgene directed conditional expression of Mem35K in leukocytes and endothelial cells, confirmed by Western blotting, flow cytometry and immunofluorescence microscopy. This conditional Mem35K expression was sufficient to increase cell surface CCL5 binding and reduce chemotaxis in vitro to CCL5, CCL2 and CCL3 but not to non-CC-CK chemoattractants, LTB4, C5a or chemerin. However, in vivo monocyte recruitment into the peritoneum driven by zymosan
Predicted to have Roundabout binding activity and heparin binding activity. Predicted to be involved in axon guidance and negative chemotaxis. Predicted to localize to the integral component of ... Predicted to have Roundabout binding activity and heparin binding activity. Predicted to be involved in axon guidance and negative chemotaxis. Predicted to localize to the integral component of membrane. Is expressed in cardiovascular system; hematopoietic system; ventral mesoderm; and yolk syncytial layer. Orthologous to human LRRC15 (leucine rich repeat containing 15). ...
The neural basis of chemotaxis in C. elegans has been studied for years. As sensory inputs, the responses of neurons to chemical cues, such as odor and salts, have been well described (Chalasani et al., 2007; Suzuki et al., 2008). As behavioral outputs, two major strategies for chemotaxis are known: (1) klinokinesis, in which the animal changes the frequency of a complex turning behavior that consists of consecutive short reversals and omega turns, and (2) klinotaxis, in which the animal gradually curves during forward locomotion in response to the chemical gradient perpendicular to the body axis (Pierce-Shimomura et al., 1999; Iino and Yoshida, 2009).. Recent studies on chemotaxis to odor have provided a better understanding of the neural mechanisms that connect these sensory inputs to behavioral outputs. AWC chemosensory neurons show calcium responses to the removal of odor, such as isoamyl alcohol or butanone (Chalasani et al., 2007). Three major interneuron classes that are postsynaptic to ...
One assay that deserves to be explain is the Multi-capillary assay. It uses 96-well PVC microplates as chemotaxis chamber and 1μl glass capillaries. You can see a picture of it in figure 4, at the left. We designed this chemotaxis assay when we were looking for a good way to perform numerous and simultaneous capillary assays. The assembly of the assay required to make holes in a microplate lid to allow glass capillaries to go through it. The lid is put upside down over the microplate and it is filled with 2% agarose gel. We also used parafilm to avoid that the gel drip through the lid holes while it was still humid. The function of the gel is to hold capillaries, in its dry way. In orther to fill capillaries we closed one of its ends by heating and heated the glass; then it was introduce in a attractant or buffer suspension and automatically it is filled. It is important to introduce the capillaries in the lid and gel by its closed end to keep the sterility on the other end. Then it is only ...
In 1975 our laboratory reported that a methylated membrane protein is involved in bacterial chemotaxis (Kort et al., 1975). It is now known that the extent of methylation of this protein (called MCP...
In article ,9411040146.AA25636 at eliris.med.yale.edu,, lolis at ELIRIS.MED.YALE.EDU (elias lolis) wrote: , Does anyone have any strong opinions on what the most effective apparatus is , for doing neutrophil chemotaxis assays? The Boyden-chamber seems to be , heavily used but there appear to be other systems that do the job. Specifically, , does anyone know the relative advantages/disadvantages of using the 48-well , microchamber from Neuroprobe or any of the products sold by Costar. I am , a protein biochemist who will shortly set up to do these chemotaxis assays , (Ive never done them before) and any help or references would be appreciated. , , Elias Dear Elias, The Costar transwells are small, relatively cheap, disposable items. It is possible to culture cells on the filters and observe penetration through the monolayer. They are simple to set up but use a lot of solutions and require you to cut out each filter from the frame by hand, which is quite a pain. I dont know if Costar has ...
To date, we have not tested the fixation of cells in gel inside the observation area of µ-Slide Chemotaxis. From tube formation assays, we generally know that fixation, permeabilization, blocking, and staining of cells on Matrigel™ is possible. Therefore, it should also be possible to do immunostainings in the 3D chemotaxis assay. In this case, we recommend removing the liquid from one reservoir and successively filling the second reservoir with the different solutions. We can assume that the incubation time should be increased by a factor of 4, in order to give the solutions sufficient time to diffuse into the observation area. The filling of liquids should be carefully done, in order not to push out the gel from the observation area.. ...
We show in this report that E. coli remodels its chemosensory physiology as a response to swarming. The altered physiology is likely the result of an elevation of the concentration of CheZ, which increases CheY∼P dephosphorylation bias and reduces the cells tumble bias. Reducing the tumble bias improves swarming performance, but a very low tumble bias negatively impacts expansion of the swarm, corroborating previous reports that tumbling is still necessary in the swarm (49). Therefore, there is an optimal tumble bias for swarming and E. coli is able to adapt its motility behavior to surface conditions that favor swarming.. The increased stability of CheZ in swarmer cells explains the increase in their CheZ levels (Fig. 6). However, the mechanism by which CheZ is specifically stabilized during swarming will require further investigation. In B. subtilis, contact with swarm agar increases synthesis of flagella by somehow sequestering a specific adaptor protein that otherwise (in liquid), in ...
Lamb, DJ, Modjtahedi, H, Plant, NJ and Ferns, GAA (2004) EGF mediates monocyte chemotaxis and macrophage proliferation and EGF receptor is expressed in atherosclerotic plaques ...
The Laboratory of Cellular and Molecular Biology (LCMB) has a long and distinguished history in the study of signal transduction mechanisms that control normal cell growth and, when altered, lead to malignant transformation. Through the 1980s and 1990s many critical signaling molecules including growth factors, growth factor receptors and intracellular transduction molecules were first identified and characterized in the LCMB. The mission of LCMB remains focused on performing cutting-edge, world-class research in this field of biology, and important discoveries continue. The goals of the six LCMB investigators cover a wide range of questions. They focus on defining signaling components and pathways and understanding their regulation. The relationship of signaling to cellular growth and death, transcriptional regulation, mitosis, cellular differentiation and organogenesis, cell adhesion, motility and chemotaxis are more complex topics under investigation. Alterations in signaling leading to ...
Signalling interactions between gametes are fundamental for sex. They entail both diffusible and surface bound signals that serve for partner attraction and recognition, and gamete communication during fusion [26,53-55]. These interactions are nearly always asymmetric so that gametes send and receive signals in a mating-type- or sex-specific manner. In this work, we ask whether asymmetric signalling enhances the efficiency of the signalling interaction itself, a theory first proposed in the 1980s [23].. Some general principles emerge from our analysis. Non-chemotactic cells can improve their search for a partner when they move in fixed directions for longer periods of time (high persistence, figure 3a). That straight-line movement can optimize a random search has been shown before in a different context (see Li et al. and references therein [33]). When cells are unable to maintain a fixed directionality for prolonged periods, symmetric chemotaxis (all cells send and receive the same signal) can ...
Shop Endothelial cell-specific chemotaxis regulator ELISA Kit, Recombinant Protein and Endothelial cell-specific chemotaxis regulator Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
Used to investigate chemotaxis of fast or slow migrating adherent cells and non-adherent cells in gel matrices Chemotaxis measurement in real-time Stable gra...
The in-cylinder tumble intensity of GDI engine is crucial to combustion stability and thermal efficiency, required to be different for the different operation conditions. A new variable tumble system (VTS) applied to GDI engine was introduced to meet tumble ratio requirements in various situations. The transient gas exchange of four combustion systems all were investigated during both intake and compression strokes based on CFD simulation, namely (1) Case 1-Intake port B (with flap valve)/Spherical piston crown; (2) Case 2-Intake port B (without flap valve)/Spherical piston crown; (3) Case 3- Intake port A/Spherical piston crown; (4) Case 4-Intake port A/Dented piston crown. The simulated results of dynamic tumble ratio showed that during the whole intake process the dynamic tumble ratio of Case1 was obviously higher than other Cases with the same boundary conditions, and the maximum value was about 5∼6 times higher. The crank angle range, in which the strong tumble motion fully developed, was ...
The overall movement of a bacterium is the result of alternating tumble and swim phases. If one watches a bacterium swimming in a uniform environment, its movement will look like a random walk with relatively straight swims interrupted by random tumbles that reorient the bacterium. Bacteria such as E. coli are unable to choose the direction in which they swim, and are unable to swim in a straight line for more than a few seconds due to rotational diffusion. In other words, bacteria "forget" the direction in which they are going. Given these limitations, it is remarkable that bacteria can direct their motion to find favorable locations with high concentrations of attractants (usually food) and avoid repellents (usually poisons). In the presence of a chemical gradient bacteria will chemotax, or direct their overall motion based on the gradient. If the bacterium senses that it is moving in the correct direction (toward attractant/away from repellent), it will keep swimming in a straight line for a ...
Tindall, M. J. and Porter, S. L. and Wadhams, G H and Maini, P. K. and Armitage, J. P. (2009) Spatiotemporal modelling of CheY complexes in escherichia coli chemotaxis. Progress in Biophysics Molecular Biology, 100 (1-3). pp. 40-46. ...
PH-domain translocation with uniform stimulus. Kinetic analysis of the translocation from the cytoplasm to the plasma membrane of GFP-tagged CRAC (Cytosolic Regulator of Adenylyl Cyclase-a PH domain containing protein) in response to a uniform increase in chemoattractant concentration. Frames were taken every 2 seconds. The chemoattractant was added just before the cell goes out of focus. From C.A. Parent and P.N. Devreotes, Johns Hopkins Medical Institutions ...
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1BDJ: Structure of the histidine-containing phosphotransfer (HPt) domain of the anaerobic sensor protein ArcB complexed with the chemotaxis response regulator CheY.
In this paper detailed long time asymptotics are calculated for a chemotaxis equation with a logarithmic chemotactic sensitivity which is coupled to an ODE. We consider the radial symmetric setting in any space dimension. The ODE describes a non-diffusing chemical, which is produced by the chemotactic species itself. Intuitively this model can be related to self-attracting reinforced random walks for many particles. Thus the behavior crucially differs with respect to existence of global solutions and the occurrence of finite or infinite time blow-up if compared to the classical Keller-Segel model. Blow-up is more likely to happen in lower dimensions in the present case. This PDE-ODE system is, among others, used in the literature to model haptotaxis and angiogenesis. ...
ABSTRACT: Vertical distributions of viable (most probable number, MPN) aerobic chemoautotrophic thiobacilli-like sulfur-oxidizing bacteria (ca. 70 samples in triplicate for MPN counts) and dark 14C-bicarbonate incorporation rates were analyzed in a series of sulfide-rich lakes. A special device for sampling sharply stratified populations on the scale of a few centimeters was used. Detailed analyses focused on the oxic-anoxic transition zone where aerobic sulfur-oxidizing bacteria should display positive chemotaxis, and in both fully oxic epilimnia and sulfide-rich anoxic hypolimnia. Kinetics of sulfide and thiosulfate potential oxidations in the presence of oxygen were followed in microcosm enrichments in one of the lakes. The highest MPN counts (,104 to 105 cells ml-1) were observed at the oxic-anoxic interfaces and in the depleted hypolimnia (1.3 ± 4.4 × 104 cells ml-1), whereas 1 order of magnitude lower concentrations were detected in the epilimnia (1.0 ± 2.3× 103 cells ml-1). Dark ...
We present a coupled kinetic-macroscopic equation describing the dynamic behaviors of Cucker-Smale(in short C-S) ensemble undergoing velocity jumps and chemotactic movements. The proposed coupled model consists of a kinetic C-S equation supplemented with a turning operator for the kinetic density of C-S particles, and a reaction-diffusion equation for the chemotactic density. We study a global existence of strong solutions for the proposed model, when initial data is sufficiently regular, compactly supported in velocity and has finite mass and energy. The turning operator can screw up the velocity alignment, and result in a dispersed state. However, under suitable structural assumptions on the turning kernel and ansatz for the reaction term, the effects of the turning operator can vanish asymptotically due to the diffusion of chemical substances. In this situation, velocity alignment can emerge algebraically slow. We also present parabolic and hyperbolic Keller-Segel models with alignment ...
Proposed path for GC chemotaxis induced by netrin binding with DCC receptors.Solid arrows indicate the prevalent direction of chemical reactions, the dashed arr
E. Coli (and many other bacteria) rely heavily upon chemotaxis in order to find areas of food and keep out of areas of harmful substances. One of the im...
Roberts, M.A.J. and August, E. and Hamadeh, A. and Maini, P. K. and McSharry, P. E. and Armitage, J. P. and Papachristodoulou, A. (2009) A model invalidation-based approach for elucidating biological signalling pathways, applied to the chemotaxis pathway inR. sphaeroides. BMC Systems Biology, 3 (3). pp. 1-14. ...
Actin in chemotaxis Cells expressing GFP-actin are observed as they were chemotaxing towards a micropipette filled with cAMP. The tip of the pipette is moved into different positions as indicated. Images were captured every 18 seconds. From K. Barisic, M. Ecke, C. Heizer, M. Maniak, M. Westphal, R. Albrecht, G. Gerisch, Max-Planck-Institut fur Biochemie, Martinsried, Germany ...
Human neutrophils (white blood cells) are attracted to a chemotactic agent in this time-lapse video. This is one of many videos available for the classroom or broadcast.
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سال انتشار: ۱۳۸۲ محل انتشار: یازدهمین کنفرانس مهندسی پزشکی ایران تعداد صفحات: ۴ نویسنده(ها): Nasrollah Rezaei-Ghaleh - PhD student, Institute of Biochemistry
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Chemotaxis, or directed cell migration, is important in many biological processes such as embryonic development, wound healing, and the direction of immune cells to sites of inflammation or infection. When not regulated properly, chemotaxis is implicated in disease states including inflammatory diseases and cancer metastasis. During eukaryotic chemotaxis, cells are able to sense a chemical gradient through receptors on the cell membrane that trigger complicated intracellular signaling networks, ultimately resulting in changes in the actin cytoskeleton leading to cell migration. The proteins involved in these signaling networks require tight spatiotemporal regulation, and the mechanisms underlying this regulation are not well understood. The work of this dissertation aims to better elucidate the pathways that regulate chemotaxis and enable cells to respond and adapt to changes in the chemoattractant gradient. To this end, we utilized the model organism Dictyostelium discoideum, and focused on ...
Dictyostelium mutants lacking the MAP kinase DdERK2 show reduced chemotactic responses to folate and cAMP. Analysis of cAMP chemotaxis shows that Dderk2{dollar}\sp-{dollar} cells are defective in chemotaxis to high concentrations of cAMP. This defect is due to an inability to repolarize in the continued presence of high concentrations of cAMP. Under these conditions, the speed of movement of mutant cells remains low. Instead of generating a leading pseudopod, mutant cells generate transient crown-like structures over multiple regions of the cell surface. These structures differ from pseudopods in that they contain myosin II as well as F actin and coronin. These studies identify a role for MAP kinases in coordinating the formation of cell projections generated in response to chemoattractants. A polyclonal antibody against a MAP kinase (DdERK2) in Dictyostelium has been made and used to study DdERK2 activation and localization. The activation of DdERK2 by chemoattractants cAMP and folate is fast ...
Nitrite plays an important role in the nitrogen metabolism of most cells, including Chlamydomonas reinhardtii. We have shown that vegetative cells of C. reinhardtii are attracted by nitrite. The Nia1nit2 mutant with defects in genes encoding the nitrate reductase and regulatory protein NIT2 respectively was found to exhibit normal chemotaxis to nitrite. The data suggest that chemotaxis events appear to be specific and independent of those involved in nitrate assimilation. Unlike vegetative cells and noncompetent pregametes, mature gametes did not show chemotaxis to nitrite. Just like gamete formation, the change in chemotaxis mode is controlled by the sequential action of two environmental cues, removal of nitrogen from the medium and light. Comparative analysis of wild-type and RNAi strains with reduced level of phototropin has indicated that switch-off of chemotaxis towards nitrite is dependent on phototropin. The studies revealed individual elements of the phototropin-dependent signal transduction
Current approaches to study chemotaxis are limited by gradient instability, low throughput, cumbersome manual manipulations, high cell number requirements, inability to acquire high-content data, and/or poor data quality and reproducibility. We present here a new microfluidics-based approach to study leukocyte chemotaxis. The device features strong miniaturization of the use of cells (,12,000 cells per data point). The microfluidic channels in the device are arrayed in 96 well format and can be operated by standard liquid handling robotics or by handheld pipettors. Cells migrate along a surface in the presence of a stable gradient of chemoattractant that is maintained for at least three hours. We show the ability to obtain consistent dose response curves to chemoattractants as well as chemotactic inhibitors with the device. Because cells are microscopically accessible, the information content is high. Not only can the number of cells migrated be assessed, but also migration distances of ...
Cell migration is an essential component of most biological processes, including: immune responses, blood vessel formation, tumor metastasis, and wound healing [1]. Effective in vitro models of directed cell migration, or chemotaxis, are necessary for both basic research and drug discovery [2]. This application note describes a new methodology for studying chemotactic cell migration using the IncuCyte® ZOOM Live-Cell Imaging system. This novel approach enables real-time visualization and automated analysis of chemotactic migration in a 96-well format within a tissue culture incubator.. By incorporating a made-for-purpose, optically clear membrane into a transmembrane geometry, the IncuCyte® chemotaxis assay facilitates the label-free visualization and quantitation of directed cell migration. The design of the IncuCyte® ClearView 96-Well Cell Migration Plate ensures a stable gradient over 72 hours and requires only 1,000-5,000 cells per well. In contrast to traditional Boydenchamber ...
Chemorepulsion is the directional movement of a cell away from a substance. Of the two directional varieties of chemotaxis, chemoattraction has been studied to a much greater extent. Only recently have the key components of the chemorepulsive pathway been elucidated. The exact mechanism is still being investigated, and its constituents are currently being explored as likely candidates for immunotherapies. The mechanism of the chemorepulsion of immune cells was first acknowledged by medical researchers at the Massachusetts General Hospital in Boston in early 2002. The phenomenon was originally referred to as "reverse chemotaxis," and later, "fugetaxis" (derived from the Latin words fugere, to flee from; and taxis, movement). For a time, the words were used interchangeably before being replaced almost exclusively by "chemorepulsion." While "chemorepulsion" applies to all cell types, the term "immunorepulsion" is gaining momentum as a more specific term that only applies to hematopoietic blood cell ...
In addition to the steepness of the gradient, the context in which a cell perceives a chemoattractant gradient can have a profound effect on their response to the chemotactic stimulus. For example, both our group (Heit et al., 2005) and others (Ferguson et al., 2007) have demonstrated that neutrophil chemotaxis to fMLP is profoundly impacted by the makeup of the substratum upon which the cell is crawling. For example, ligands for LFA-1, MAC-1 and VLA-4 need to be present to get a full chemotactic response to fMLP (Heit et al., 2005). Moreover, Ferguson et al. have demonstrated profound differences in the chemotaxis of neutrophils to fMLP on glass verses protein substrata (Ferguson et al., 2007). These profound differences in the behavior of neutrophils, based on the substratum they are crawling upon, demonstrate that careful selection of the substratum is an important factor when selecting or designing chemotactic assays, especially in mammalian systems. In this regard, we have used a ...
C1q, the first component of the classical pathway of the complement system, interacts with various cell types and triggers a variety of cell-specific cellular responses, such as oxidative burst, chemotaxis, phagocytosis, etc. Different biological responses are attributed to the interaction of C1q with more than one putative cell-surface C1q receptor/C1q-binding protein. Previously, it has been shown that C1q-mediated oxidative burst by neutrophils is not linked to G-protein-coupled fMet-Leu-Phe-mediated response. In the present study, we have investigated neutrophil migration brought about by C1q and tried to identify the signal-transduction pathways involved in the chemotactic response. We found that C1q stimulated neutrophil migration in a dose-dependent manner, primarily by enhancing chemotaxis (directed movement) rather than chemokinesis (random movement). This C1q-induced chemotaxis could be abolished by an inhibitor of G-proteins (pertussis toxin) and PtdIns(3,4,5)P3 kinase (wortmannin and ...
The sequential and regulated recruitment of leukocytes into tissues by chemoattractants is essential for effective clearance of pathogens and healing. The Rho GTPases Cdc42, Rac, and Rho are important for establishing and maintaining migratory polarity. Most chemoattractants for phagocytes signal either through seven transmembrane G-protein-coupled receptors (GPCRs) or tyrosine kinase receptors. Y721 is the most important for chemotaxis because it recruits phospholipase-C-γ (PL C-γ) and the p85 subunit of class 1A PI3Ks, both of which are implicated in the initiation of chemotaxis. Several intracellular signaling complexes contribute to the polarization of phagocytes in response to chemoattractants, and they probably act together to allow optimal chemotaxis. Cdc42 is implicated in multiple types of cell polarity, including axon specification, yeast mating, and epithelial polarity. There are several PLC isoforms, of which PLCβ2 and PLCβ3 are activated by GPCR signaling in neutrophils, whereas PLCβ
Eukaryotic amoebae Dictyostelium discoideum (referred as Dictyostelium) in the vegetative state forage on bacteria by following gradients of folic acid (FA), a by-product of bacterial metabolism [1,2]. It is currently believed that Dictyostelium measure chemical gradients directly by monitoring the distribution of the occupied chemoattractant receptors. These cells can detect concentration differences as low as a few per cent across their cell bodies [3-8] and it is currently an open question what exactly limits this process. Previously, the receptor-ligand binding fluctuations were suggested as the limiting factor, which remains a possibility because a single excited receptor may amplify the signal by activating multiple G-proteins [9-11].. The chemotaxis signalling system can be described as the following Shannon communication channel [12,13]: the chemoattractant gradient direction as the input, the spatial distribution of occupied receptors as the intermediate step and the direction of cell ...
Chemotaxis is the primary mechanism by which cell movements are directed within multicellular organisms, and it is a major component of embryonic development, wound healing, and immune responses. Chemotaxis involves a complex cascade of events--formation of signaling complexes, receptor polarization, adhesion molecule activation, and cytoskeletal reorganization. Previous assay methods were limited in several ways that reduced users abilities to obtain quantitative data or to control conditions precisely. We describe a unique chemotactic assay that can incorporate multiple chemotactic gradients in different spatial and temporal combinations. In addition, this assay is easily adapted for live-cell imaging and fluorescent microscopy. With its relative simplicity, flexibility, and precision, this method is a key tool for the study of cellular chemotactic responses and the signaling processes underlying them. ...
The heterogeneity of the H460 large cell lung cancer cell line was investigated by selecting for chemokinetic cells from a CON population that demonstrated both chemokinesis and chemotaxis. Using Boyden chambers, cells that migrated under chemokinetic conditions were collected and their numbers expanded. Time-lapsed microscopy under isotropic conditions showed that KINE cells moved faster and changed directions more frequently than CON confirming their chemokinetic character. KINE cells which lacked stable focal adhesion were also less adhesive to culture plates compared to CON cells which had focal adhesions at the leading edge shown by phospho-Paxillin-tyr118 antibody labeling. Weak substrate adhesion in KINE cells may account for motile characteristics of rapid and random movement [16-19]. Furthermore, the selection for increased chemokinesis did not compromise the ability of KINE cells to chemotax. KINE cells were also significantly more invasive compared to CON.. These results underscore ...
Studies in Dictyostelium have shown that the p110-related phosphatidylinositol-3-kinases PI3K1 and PI3K2 are required for proper development, pinocytosis chemotaxis, and chemoattractant-mediated activation of PKB. Insights into the mechanism by which PI3K regulates chemotaxis derive from studies on PKB in mammalian leukocytes and Dictyostelium cells. PKB activation requires its translocation to the plasma membrane by binding of its PH domain to PtdIns(3,4,5)P3 and PtdIns(3,4)P2 produced upon activation of PI3K, leading to PKB activation. In leukocytes and Dictyostelium cells, chemoattractants mediate PKB activation through a G-protein-coupled pathway that requires the activity of the respective PI3Ks. Chemoattractant stimulation of neutrophils and Dictyostelium cells results in a transient localization of a GFP fusion of the PH domains from the Dictyostelium and mammalian PKBs to the plasma membrane. When these cells are placed in a chemoattractant gradient, membrane localization of the ...
Chemotaxis in Pseudomonas aeruginosa.: A chemotaxis system for Pseudomonas aeruginosa was defined by using the method of Adler. Cells were attracted to compound
Decision making is one of the distinguishing properties of biosystems. Decision making of course does not necessarily mean conscious decision making, which is exclusively human. On the contrary, the ability to make decisions can be observed in every living organism even in unicellular species as a type of molecular logic, in the form of chemotaxis). Chemotaxis is chemistry-driven motility: towards areas of increasing concentrations of friendly chemicals (positive chemotaxis) and away from increasing concentrations of hostile chemicals (negative chmotaxis). ...
BioAssay record AID 297157 submitted by ChEMBL: Inhibition of CXCL8-induced cell migration in human PMN cells at 0.01 uM by chemotaxis assay.
The rotation of the flagellum and the direction of movement is often regulated by sensory stimuli, allowing the cell to migrate towards attractive signals. In E.coli this is achieved through a signal transduction system that controls the phosphorylation state of the response regulator protein CheY. In the absence CheY-P the flagellum rotates CWW in a "run" state. The presence of CheY-P, induces a switch to CW rotation resulting in "tumbling" which randomly reorients the cell. When an attractant binds to a receptor it initiates a conformational change and downstream cascade that leads to suppression of CheA, a protein that normally phosphoryates CheY to CheY-P. The absence of CheY-P causes the flagellum to remain in the "run" state leading to migration towards the signal. A third protein, CheZ helps regulate the circuit by preventing the accumulation of CheY-P through dephosphorylation. The 2009 Imperial College of London igem team attempted to engineer e.coli chemotaxis towards malate so that ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
Gradients are ubiquitous drivers of spatially differentiated behavior and communication in biological systems. For example, stripes of mRNA concentrations generated by reaction-diffusion (RD) processes in the embryo of the fruit fly Drosophila act as chemical blueprints to direct the growth of the embryo.1,2 A variety of spatial concentration patterns also arise during intercellular signaling processes.3,4 Synthetic patterns have been generated in vitro to study and control chemotaxis,5 angiogenesis,6 stem cell proliferation and differentiation,7 axon growth,8 cell culture and cell behavior in hydrogels,9,10 and protein expression.11 Chemical gradients have also been used to control reactivity, direct mechanical actuation, pattern synthetic materials and orchestrate self-regeneration.12-14 Chemical gradients are often produced using lithographic or light-driven patterning methods that encode variations of density of a molecule along a surface or within a 3-dimensional material,15-17 or by ...
Luckily, medicines can change whats missing (like insulin) or they can hindrance production of a chemical when the torso is making too much of it. The chic division close to the Access to Medicine Foundation shows which large pharmaceutical companies are marketing the most vital medicines and vaccines in the direction of the highest-burden bug in developing countries. All fluoroquinolones modestly impair puke macrophage chemotaxis (Labro 2000) and transendothelial leucocyte and monocyte migration (Uriarte et al 2004) purchase 20 mcg atrovent free shipping symptoms vs signs. DISCERN: TENS SUPPLIES READY PRO EMPIВ® CUSTOMERS We no longer conduct EmpiВ® TENS units and electrodes. We make it effortlessly representing you to boon the materiel that you are seeking next to breaking down our vast batch into categories based on the listing of injuries, Flick through online looking for peaceful medical supplies close brands, price, one of a kind offers and discounts and other categories. These are ...
Mast cells (MCs) are forceful multifunctional effector cells of the immune system. MCs are normally distributed throughout connective and mucosal tissues, but in several pathological conditions accumulation of MCs occur. This accumulation is probable due to directed migration of MCs and they are subjects for migration at least two different occations: 1) when they are recruited as progenitor cells from the blood into the tissue; and 2) when they as mature MCs are recruited to sites of inflammation. The aim of this study was to investigate MC migration to chemoattractants released in vivo or in vitro (body fluids collected from patients with asthma or rheumatoid arthritis and TH1- and TH2-cytokines) and to recombinant cytokines (transforming growth factor -β (TGF-β) and CCL5/RANTES).. This thesis shows that bronchoalveolar lavage (BAL) fluid from asthmatic patients and synovial fluid from patients with rheumatiod arthritis contain MC chemoattractants, and that part of the chemotactic activity ...
Xuehua Xu is the author of these articles in the Journal of Visualized Experiments: Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum, Imaging G Protein-coupled Receptor-mediated Chemotaxis and its Signaling Events in Neutrophil-like HL60 Cells
BioAssay record AID 147686 submitted by ChEMBL: Compound was evaluated for the inhibition of LTB4 receptor -induced chemotaxis of isolated human neutrophils; IA means inactive.
Evaluating Chemotaxis in the stages of wound healing, the factors that regulate keratinocyte migration over the wound bed are relatively unknown.
Hardcore continuum re-constructionist Etch continues his junglist-referencing production sensibilities with a blistering four-track outing on Space + Time Records. A side Chemotaxis is the jazzy tip - licks of rhodes chords cascade against immaculately produced breaks, conjuring a nice contrast between the warmth of
Irimia and Toner made a large number of plastic "chips" shot through with a series of microscopic channels 6 to 100 micrometres wide and lined with proteins like those found in connective tissue, such as collagen. The progress of cells down the channels can be tracked under a microscope.. The researchers seeded the devices with human cancer cells, including cells of lung, prostate and breast cancer. "We thought that by confining cancer cells in small channels in the presence of [chemical] gradients we could better replicate the mechanical and chemical interactions that these cells have inside tissues," Irimia says.. The first results were unexpected. Cells of all kinds, whether healthy or diseased, typically navigate by using chemical gradients - differences in chemical concentrations - as navigation beacons. But even in control devices without such gradients most cancer cells tested began to head in one direction along the channels without stopping, some for more than 12 hours. ...
InterPro provides functional analysis of proteins by classifying them into families and predicting domains and important sites. We combine protein signatures from a number of member databases into a single searchable resource, capitalising on their individual strengths to produce a powerful integrated database and diagnostic tool.
InterPro provides functional analysis of proteins by classifying them into families and predicting domains and important sites. We combine protein signatures from a number of member databases into a single searchable resource, capitalising on their individual strengths to produce a powerful integrated database and diagnostic tool.
Motility is achieved in most bacterial species by the flagellar apparatus. It consists of dozens of different proteins with thousands of individual subunits. The published literature about bacterial chemotaxis and flagella ...
Sigma-Aldrich offers abstracts and full-text articles by [Michael Hannigan, Lijun Zhan, Zhong Li, Youxi Ai, Dianqing Wu, Chi-Kuang Huang].
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TY - JOUR. T1 - Prolactin suppression of leukocyte chemotaxis in vitro. AU - Harris, R. D.. AU - Kay, N. E.. AU - Seljeskog, E. L.. AU - Murray, K. J.. AU - Douglas, S. D.. PY - 1979/1/1. Y1 - 1979/1/1. N2 - Leukocyte chemotaxis in vitro was studied for cells from patients with pituitary adenomas. Leukocytes obtained preoperatively from two of three patients with elevated serum prolactin levels demonstrated chemotaxic alterations described in other malignant disease. Statistically significant suppression of chemotaxis occurred in the leukocytes of four of 12 specimens from normal donors at concentrations of 1000 ng/ml, and in four of eight specimens at 2000 ng/ml of prolactin in preincubation media. Thus prolactin concentration may influence the motility of leukocytes. The variable neoplastic behavior of morphologically similar pituitary adenomas may, in part, reflect a neurohormonally altered host response to the presence of these lesions.. AB - Leukocyte chemotaxis in vitro was studied for ...
Bacterial chemotaxis, a remarkable behavioral trait which allows bacteria to sense and respond to chemical gradients in the environment, has implications in a broad range of fields including but not limited to disease pathogenesis, in-situ bioremediation and marine biogeochemistry. And therefore, studying bacterial chemotaxis is of significant importance to scientists and engineers alike. Microfluidics has revolutionized the way we study the motile behavior of cells by enabling observations at high spatial and temporal resolution in carefully controlled microenvironments. This thesis aims to explore the potential of microfluidic technology in studying bacterial behavior by investigating different aspects of bacterial chemotaxis on a microfluidic platform. We quantified population-scale transport parameters of bacteria using videomicroscopy and cell tracking in controlled chemoattractant gradients. Previously, transport parameters have been derived theoretically from single-cell swimming behavior ...
The Vibrio cholerae genome revealed the presence of multiple sets of chemotaxis genes, including three cheA gene homologs. We found that the cheA-2, but not cheA-1 or cheA-3, gene is essential for chemotaxis under standard conditions. Loss of chemotaxis had no effect on virulence factor expression in vitro.. ...
The cellular slime mold Dictyostelium discoideumlives in the soil where it feeds on bacteria. Exhaustion of the food supply induces cell aggregation. Subsequently, cells differentiate to two cell...
The formation of second messengers at a specific place regulates the local formation of a pseudopod. These second messengers are presumably PIP3 for the PI3K pathway, but there could be several second messengers for the PLA2 pathway. The PLA2-catalyzed hydrolysis of membrane phospholipids results in the stoichiometric production of a free fatty acid and a lysophospholipid. Both of these phospholipid metabolites may serve as potential second messengers. Recently, the first results of a genetic screen for LY294002-supersensitive chemotaxis mutants were reported (Chen et al., 2007). A gene was identified that belongs to the Ca2+-independent PLA2 (iPLA2, group VI PLA2) class, whose inactivation in a wild-type background had no effect, but inactivation in a pi3k-null background nearly completely inhibited chemotaxis, which is in excellent agreement with the present observations. The regulation of this PLA2 by upstream components requires further investigation, as well as the identification of the ...
Defects in phosphotransferase chemotaxis in cya and cpd mutants previously cited as evidence of a cyclic GMP or cyclic AMP intermediate in signal transduction were not reproduced in a study of chemotaxis in Escherichia coli and Salmonella typhimurium. In cya mutants, which lack adenylate cyclase, the addition of cyclic AMP was required for synthesis of proteins that were necessary for phosphotransferase transport and chemotaxis. However, the induced cells retained normal phosphotransferase chemotaxis after cyclic AMP was removed. Phosphotransferase chemotaxis was normal in a cpd mutant of S. typhimurium that has elevated levels of cyclic GMP and cyclic AMP. S. typhimurium crr mutants are deficient in enzyme III glucose, which is a component of the glucose transport system, and a regulator of adenylate cyclase. After preincubation with cyclic AMP, the crr mutants were deficient in enzyme II glucose-mediated transport and chemotaxis, but other chemotactic responses were normal. It is concluded ...
Cluster II che Genes from Pseudomonas aeruginosa Are Required for an Optimal Chemotactic Response: Pseudomonas aeruginosa, a γ-proteobacterium, is motile by mea
A mathematical model which incorporates the spatial dispersal and interaction dynamics of mistletoes and birds is derived and studied to gain insights of the spatial heterogeneity in abundance of mistletoes. Fickian diffusion and chemotaxis are used to model the random movement of birds and the aggregation of birds due to the attraction of mistletoes, respectively. The spread of mistletoes by birds is expressed by a convolution integral with a dispersal kernel. Two different types of kernel functions are used to study the model, one is {\color{green} a} Dirac delta function which reflects the extreme case that the spread behavior is local, and the other one is a general non-negative symmetric function which describes the nonlocal spread of mistletoes. When the kernel function is taken as the Dirac delta function, the threshold condition for the existence of mistletoes is given and explored in term of parameters. For the general non-negative symmetric kernel case, we prove the existence and ...
In contrast to Escherichia coli, a model organism for chemotaxis that has 5 chemoreceptors and a single chemosensory pathway, Pseudomonas aeruginosa PAO1 has a much more complex chemosensory network, which consists of 26 chemoreceptors feeding into four chemosensory pathways. While several chemoreceptors were rigorously linked to specific pathways in a series of experimental studies, for most of them this information is not available. Thus, we addressed the problem computationally. Protein-protein interaction network prediction, coexpression data mining, and phylogenetic profiling all produced incomplete and uncertain assignments of chemoreceptors to pathways. However, comparative sequence analysis specifically targeting chemoreceptor regions involved in pathway interactions revealed conserved sequence patterns that enabled us to unambiguously link all 26 chemoreceptors to four pathways. Placing computational evidence in the context of experimental data allowed us to conclude that three ...
The effect of therapeutic concentrations of D-penicillamine, sodium aurothiomalate, and levamisole on in vitro neutrophil chemotaxis and random migration in normal subjects and patients with rheumatoid arthritis was studied. D-penicillamine produced no changes. Sodium aurothiomalate produced dose-related reductions in chemotaxis in normal subjects and in patients who had a good clinical response to gold therapy, while patients who had failed to respond to gold showed a minimal nondose dependent reduction. Levamisole produced dose-dependent stimulation of chemotaxis, a greater effect found with the patients cells. Neutrophil chemotaxis improved to normal values in most patients responding to several months of D-penicillamine treatment but showed an immediate and marked stimulation in patients treated with levamisole. ...
Catechins, flavanols found at high levels in green tea, have received significant attention due to their potential health benefits related to cancer, autoimmunity and metabolic disease, but little is known about the mechanisms by which these compounds affect cellular behavior. Here, we assess whether the model organism Dictyostelium discoideum is a useful tool with which to characterize the effects of catechins. Epigallocatechin gallate (EGCG), the most abundant and potent catechin in green tea, has significant effects on the Dictyostelium life cycle. In the presence of EGCG aggregation is delayed, cells do not stream and development is typically stalled at the loose aggregate stage. The developmental effects very likely result from defects in motility, as EGCG reduces both random movement and chemotaxis of Dictyostelium amoebae. These results suggest that catechins and their derivatives may be useful tools with which to better understand cell motility and development in Dictyostelium and that this
TY - JOUR. T1 - Cell-cell contact, cyclic AMP, and gene expression during differentiation of the cellular slime mold Dictyostelium discoideum.. AU - Blumberg, D. D.. AU - Chung, S.. AU - Landfear, Scott. AU - Lodish, H. F.. PY - 1982. Y1 - 1982. UR - http://www.scopus.com/inward/record.url?scp=0020021927&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=0020021927&partnerID=8YFLogxK. M3 - Article. C2 - 6289353. AN - SCOPUS:0020021927. VL - 85 Pt B. SP - 167. EP - 182. JO - Progress in Clinical and Biological Research. JF - Progress in Clinical and Biological Research. SN - 0361-7742. ER - ...
CXCR4 is the Gi protein-linked seven-transmembrane receptor for the alpha chemokine stromal cell-derived factor 1 (SDF-1), a chemoattractant for lymphocytes. This receptor is highly conserved between human and rodent. CXCR4 is also a coreceptor for entry of human immunodeficiency virus (HIV) in T cells and is expressed in the CNS. To investigate how these CXCR4 ligands influence CNS development and/or function, we have examined the expression and signalling of this chemokine receptor in rat neurons and astrocytes in vitro. CXCR4 transcripts and protein are synthesized by both cell types and in E15 brain neuronal progenitors. In these progenitors, SDF-1, but not gp120 (the HIV glycoprotein), induced activation of extracellular signal regulated kinases (ERKs) 1/2 and a dose-dependent chemotactic response. This chemotaxis was inhibited by Pertussis toxin, which uncouples Gi proteins and the bicyclam AMD3100, a highly selective CXCR4 antagonist, as well as by an inhibitor of the MAP kinase pathway. In
Endothelial cell migration is a critical event during angiogenesis, and inhibitors of cell motility can affect the angiogenic process. Paclitaxel (Taxol(R)), a microtubule-stabilizing antineoplastic cytotoxic drug, inhibits motility and invasiveness of several cell types. The aim of this study was to investigate the effect of paclitaxel on endothelial cell functions and on angiogenesis. In vivo, paclitaxel (20-28 mg/kg i.v.) significantly inhibited the angiogenic response induced by tumor cell supernatant embedded in a pellet of reconstituted basement membrane (Matrigel) injected s.c. into C57BL/6N mice. In vitro, paclitaxel inhibited endothelial cell proliferation, motility, invasiveness, and cord formation on Matrigel in a dose-dependent manner. The antiangiogenic activity of paclitaxel was not linked to its cytotoxicity, since inhibition of endothelial cell chemotaxis and invasiveness occurred at drug concentrations which did not affect endothelial cell proliferation. Another cytotoxic drug, ...
In this report, we provide the first evidence that blood-borne human CD4+CD25+ Treg cells exhibit a distinctive chemotactic response profile and chemokine receptor expression. Treg cells exhibit chemotactic responsiveness to several inflammatory and lymphoid chemokines, but they are specifically hyperresponsive to chemokines that engage the chemokine receptors CCR4 and CCR8 (Fig. 1).. Our investigation documents a broad spectrum of responsiveness of Treg cells to inflammatory chemokines that could potentially allow access to inflamed tissues and contact responding T cells and APCs. However, the specificity of action of chemokines such as CCL17, CCL22, and CCL1 on Treg cells suggests a unique role for these chemokines and their receptors in the physiology of Treg cells. Activated T cells and professional APCs such as DCs and monocytes/macrophages can produce CCL1, CCL17, and CCL22 (15)(16)(18). CCL17 and CCL22 secreted by activated DCs have been shown to attract activated T cells expressing CCR4 ...

ChemotaxisChemotaxis

... is called positive if movement is in the direction of a higher concentration of the chemical in question, and ... Chemotaxis is the phenomenon in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their ... In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. ... chemotaxis is critical to early development (e.g. movement of sperm towards the egg during fertilization) and subsequent phases ...
more infohttp://www.princeton.edu/~achaney/tmve/wiki100k/docs/Chemotaxis.html

Video: ChemotaxisVideo: Chemotaxis

Human neutrophils (white blood cells) are attracted to a chemotactic agent in this time-lapse video. This is one of many videos available for the classroom or broadcast.
more infohttps://www.cellsalive.com/chemotx.htm

chemotaxis assayschemotaxis assays

... Clifford Beall beall.3 at OSU.EDU Mon Nov 7 10:56:45 EST 1994 *Previous message: chemotaxis assays ... I am , a protein biochemist who will shortly set up to do these chemotaxis assays , (Ive never done them before) and any help ... for doing neutrophil chemotaxis assays? The Boyden-chamber seems to be , heavily used but there appear to be other systems that ...
more infohttp://www.bio.net/bionet/mm/immuno/1994-November/002352.html

ChemotaxisChemotaxis

... Click on title or image to view video. Chemoattractant receptors in chemotaxis ... G-protein b-subunits in chemotaxis. Confocal image of GFP-tagged Gb-subunits in living amoebae undergoing chemotaxis. The ... PH-domain translocation during chemotaxis. Confocal image of GFP-tagged CRAC in living amoebae undergoing chemotaxis. CRAC-GFP ... Digitized wild-type cell in chemotaxis. Three dimensional direct image reconstruction of a D. discoideum amoebae crawling in a ...
more infohttp://dictybase.org/Multimedia/chemotaxis/Chemotaxis.htm

One-dimensional chemotaxis kinetic model | SpringerLinkOne-dimensional chemotaxis kinetic model | SpringerLink

... we study a variation of the equations of a chemotaxis kinetic model and investigate it in one dimension. In fact, we use ... Chemotaxis equations. SIAM J. Appl. Math. 62(4), 1222-1250 (2002) (electronic)CrossRefzbMATHMathSciNetGoogle Scholar ... In this paper, we study a variation of the equations of a chemotaxis kinetic model and investigate it in one dimension. In fact ... Chalub F.A.C.C., Rodrigues J.F.: A class of kinetic models for chemotaxis with threshold to prevent overcrowding. Port. Math. ( ...
more infohttps://link.springer.com/article/10.1007%2Fs00030-010-0088-8

Chemotaxis - WikipediaChemotaxis - Wikipedia

Chemotaxis Neutrophil Chemotaxis Cell Migration Gateway Downloadable Matlab chemotaxis simulator Bacterial Chemotaxis ... Chemotaxis (from chemo- + taxis) is the movement of an organism in response to a chemical stimulus. Somatic cells, bacteria, ... Positive chemotaxis occurs if the movement is toward a higher concentration of the chemical in question; negative chemotaxis if ... 1911). "Chemotaxis". Encyclopædia Britannica. 6 (11th ed.). Cambridge University Press. p. 77. Chemotaxis Lecture. Uploaded in ...
more infohttps://en.wikipedia.org/wiki/Chemotaxis

What Is Chemotaxis? (with pictures)What Is Chemotaxis? (with pictures)

Chemotaxis is the movement of small organisms and single cells in response to chemical signals from their environment. The ... During fetal development, chemotaxis also plays a role in the movement of cells as the organism develops; budding nerve cells, ... Research on chemotaxis includes exploration into how small organisms move, when they respond to chemical signals, and what can ... Chemotaxis is movement of small organisms and single cells in response to chemical signals in the surrounding environment. This ...
more infohttps://www.wisegeek.com/what-is-chemotaxis.htm

Chemotaxis assay - WikipediaChemotaxis assay - Wikipedia

Chemotaxis Cell Migration Gateway Cytometric chemotaxis and cell migration assay Free tool based on ImageJ to analyse ... Chemotaxis assays are experimental tools for evaluation of chemotactic ability of prokaryotic or eukaryotic cells. A wide ... Zicha D.; Dunn G.A.; Brown A.F. (1991). "A new direct-viewing chemotaxis chamber". J Cell Sci. 99: 769-75. PMID 1770004. Leick ... Seymour J. R.; J. R. Ahmed; Marcos S. R (2008). "A microfluidic chemotaxis assay to study microbial behavior in diffusing ...
more infohttps://en.wikipedia.org/wiki/Chemotaxis_assay

Chemotaxis - wikidocChemotaxis - wikidoc

Chemotaxis related migratory responses. Although chemotaxis is the most frequently studied form of migration there are several ... Global Existence for Chemotaxis with Finite Sampling Radius. *Bacterial Chemotaxis Depends on a Two-Component Signaling Pathway ... Bacterial chemotaxis. Some bacteria, such as E. coli, have several flagella per cell (4-10 typically). These can rotate in two ... ca:Quimiotaxi da:Kemotaksi de:Chemotaxis eo:Kemotaksiso it:Chemiotassi he:כימוטקסיס hu:Kemotaxis sv:Kemotaxis uk:Хемотаксис ur: ...
more infohttp://wikidoc.org/index.php/Chemotaxis

DSpace@MIT: 
                Microfluidics for bacterial chemotaxis[email protected]: Microfluidics for bacterial chemotaxis

Bacterial chemotaxis, a remarkable behavioral trait which allows bacteria to sense and respond to chemical gradients in the ... Steady gradients, linear or nonlinear, are often a useful model of the bacterial microenvironment to study chemotaxis in the ... Microfluidics for bacterial chemotaxis. Research and Teaching Output of the MIT Community. ... And therefore, studying bacterial chemotaxis is of significant importance to scientists and engineers alike. Microfluidics has ...
more infohttp://dspace.mit.edu/handle/1721.1/66851

C. elegans Chemotaxis Assay | ProtocolC. elegans Chemotaxis Assay | Protocol

In nature, chemotaxis is important for organisms to sense and... ... Chemotaxis is a process in which cells or organisms move in ... Now that the chemotaxis plates and the worms are ready, we can get started on the chemotaxis assay. First, mix equal volumes of ... For example, chemotaxis is required for the movement of sperm toward an egg prior to fertilization. In the lab, chemotaxis is ... Chemotaxis is a process in which cells or organisms move in response to a chemical stimulus. In nature, chemotaxis is important ...
more infohttps://www.jove.com/science-education/5113/c-elegans-chemotaxis-assay

chemotaxis (thing) by Fluffy The Cat - Everything2.comchemotaxis (thing) by Fluffy The Cat - Everything2.com

... rely heavily upon chemotaxis in order to find areas of food and keep out of areas of harmful substances. One of the im... ... chemotaxis (thing). See all of chemotaxis, there is 1 more in this node. ... E. Coli (and many other bacteria) rely heavily upon chemotaxis in order to find areas of food and keep out of areas of harmful ...
more infohttps://everything2.com/user/Fluffy+The+Cat/writeups/chemotaxis

Chemotaxis research areaChemotaxis research area

The Chemotaxis research has been constantly evolving in recent years and many researchers are working hard to find new ... Chemotaxis. The term chemotaxis is used to describe the movement of organisms or cells in response to the presence of a ... Although both can include a number of organic and inorganic substances, the most commonly researched inducers of chemotaxis are ... Considering the significance of chemotaxis in cellular movement during a number of biological processes, including immune ...
more infohttps://www.peprotech.com/ko/chemotaxis

Chemotaxis research areaChemotaxis research area

The Chemotaxis research has been constantly evolving in recent years and many researchers are working hard to find new ... Chemotaxis. The term chemotaxis is used to describe the movement of organisms or cells in response to the presence of a ... Although both can include a number of organic and inorganic substances, the most commonly researched inducers of chemotaxis are ... Considering the significance of chemotaxis in cellular movement during a number of biological processes, including immune ...
more infohttps://www.peprotech.com/gb/chemotaxis

Novel Technologies for the Precise Monitoring of ChemotaxisNovel Technologies for the Precise Monitoring of Chemotaxis

New directions are needed in chemotaxis assays, says Lonza Biosciences. The company is forging ahead by combining microfluidics ... Chemotaxis is a major feature in a number of disease processes-utilized by wound healing, cancer, and immune cells alike. This ... A Closer Look at Chemotaxis. In order to assess the efficiency of this approach as an update to conventional migration assays, ... Chemotaxis is a mechanism that provides directional cellular movement in response to alterations in the chemical composition of ...
more infohttps://www.genengnews.com/magazine/288/novel-technologies-for-the-precise-monitoring-of-chemotaxis/

Chemotaxis legal definition of chemotaxisChemotaxis legal definition of chemotaxis

What is chemotaxis? Meaning of chemotaxis as a legal term. What does chemotaxis mean in law? ... Definition of chemotaxis in the Legal Dictionary - by Free online English dictionary and encyclopedia. ... redirected from chemotaxis). Also found in: Dictionary, Thesaurus, Medical, Acronyms, Encyclopedia, Wikipedia.. Related to ... While our proposed QBFO takes a new representation of a bacterium, and a new quantum chemotaxis operator and a new quantum ...
more infohttps://legal-dictionary.thefreedictionary.com/chemotaxis

The dynamics of protein phosphorylation in bacterial chemotaxis.  - PubMed - NCBIThe dynamics of protein phosphorylation in bacterial chemotaxis. - PubMed - NCBI

The chemotaxis signal transduction pathway allows bacteria to respond to changes in concentration of specific chemicals ( ... The dynamics of protein phosphorylation in bacterial chemotaxis.. Borkovich KA1, Simon MI. ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/2261645?dopt=Abstract

Negative Chemotaxis in Escherichia coli | Journal of BacteriologyNegative Chemotaxis in Escherichia coli | Journal of Bacteriology

Generally, non-chemotactic mutants lack both positive and negative chemotaxis, and l-methionine is required for both kinds of ... Several methods for detecting or measuring negative chemotaxis are described. Using these, we have surveyed a number of ...
more infohttps://jb.asm.org/content/118/2/560.abstract

Reaction Diffusion and Chemotaxis for Decentralized Gathering on FPGAsReaction Diffusion and Chemotaxis for Decentralized Gathering on FPGAs

... Bernard Girau,1 César Torres-Huitzil,2 Nikolaos ... Similarly, to apply rule R5 (chemotaxis rule), amoebae move to a cell that is randomly selected among the excited free cells of ... We are mostly interested in the decentralized gathering that occurs when amoebae are subject to a chemotaxis process. We now ... N. Fatès, "Gathering agents on a lattice by coupling reaction-diffusion and chemotaxis," Tech. Rep., INRIA Nancy Grand-Est, ...
more infohttps://www.hindawi.com/journals/ijrc/2009/639249/

A Sensitive Chemotaxis Assay Using a Novel Microfluidic DeviceA Sensitive Chemotaxis Assay Using a Novel Microfluidic Device

... Chen Zhang,1,2 Sunyoung Jang,1 Ovid C. Amadi,3,4 Koichi Shimizu ... Chen Zhang, Sunyoung Jang, Ovid C. Amadi, Koichi Shimizu, Richard T. Lee, and Richard N. Mitchell, "A Sensitive Chemotaxis ...
more infohttps://www.hindawi.com/journals/bmri/2013/373569/cta/

Chemotaxis: Navigating by Multiple Signaling Pathways | Science SignalingChemotaxis: Navigating by Multiple Signaling Pathways | Science Signaling

Chemotaxis: Navigating by Multiple Signaling Pathways Message Subject. (Your Name) has forwarded a page to you from Science ...
more infohttps://stke.sciencemag.org/content/2007/396/pe40/tab-e-letters

Chemotaxis: Navigating by Multiple Signaling Pathways | Science SignalingChemotaxis: Navigating by Multiple Signaling Pathways | Science Signaling

Chemotaxis: Navigating by Multiple Signaling Pathways Message Subject. (Your Name) has forwarded a page to you from Science ...
more infohttps://stke.sciencemag.org/content/2007/396/pe40/tab-figures-data

Temporal and spatial regulation of chemotaxis.  - PubMed - NCBITemporal and spatial regulation of chemotaxis. - PubMed - NCBI

Temporal and spatial regulation of chemotaxis.. Iijima M1, Huang YE, Devreotes P. ... Interference with PI3Ks alters chemotaxis, and disruption of PTEN broadens PI localization and actin polymerization in parallel ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/12408799

Stabilization in a chemotaxis model for virus infectionStabilization in a chemotaxis model for virus infection

... a qualitative analysis of a model describing the time and space dynamics of a virus which migrates driven by chemotaxis. The ... Stabilization in a chemotaxis model for virus infection. Nicola Bellomo 1, and Youshan Tao 2,, ... Keywords: Virus infection model, chemotaxis, global existence, asymptotic stability. Mathematics Subject Classification: ... E. F. Keller and L. A. Segel, Model for chemotaxis, J. Theor. Biol., 30 (1971), 225-234. doi: 10.1016/0022-5193(71)90050-6.. ...
more infohttps://www.aimsciences.org/article/doi/10.3934/dcdss.2020006

The moving boundary problem in a chemotaxis modelThe moving boundary problem in a chemotaxis model

... Hua Chen 1, and Shaohua Wu 1, ... T. Nagai, Blow-up of radially symmetric solutions to a chemotaxis system,, Adv. Math. Sci. Appl., 5 (1995), 581. Google Scholar ... T. Nagai, Blow-up of radially symmetric solutions to a chemotaxis system,, Adv. Math. Sci. Appl., 5 (1995), 581. Google Scholar ... V. Nanjundiah, Chemotaxis signal relaying and aggregation morphology,, J. Theor. Biol., 42 (1973), 63. Google Scholar ...
more infohttps://www.aimsciences.org/article/doi/10.3934/cpaa.2012.11.735
  • I've seen one with examples of neutrophil chemotaxis. (wisegeek.com)
  • This technology was used in a clinical setting to assay 34 asthmatic ( n = 23) and nonasthmatic, allergic rhinitis ( n = 11) patients to establish domains for asthma diagnosis based on neutrophil chemotaxis. (pnas.org)
  • This study identifies neutrophil chemotaxis velocity as a potential biomarker for asthma, and we demonstrate a microfluidic technology that was used in a clinical setting to perform these measurements. (pnas.org)
  • The significance of chemotaxis in biology and clinical pathology was widely accepted in the 1930s. (wikidoc.org)
  • Considering the significance of chemotaxis in cellular movement during a number of biological processes, including immune response and development, it is of no surprise that a relatively large amount of emphasis has been placed upon research concerning chemotaxis and, more specifically, the Chemokines functioning to direct cellular movement. (peprotech.com)
  • The significance of chemotaxis in biology and clinical pathology was widely accepted in the 1930s, and the most fundamental definitions underlying the phenomenon were drafted by this time. (wikipedia.org)
  • In multicellular organisms, chemotaxis is critical to early development (e.g. movement of sperm towards the egg during fertilization ) and subsequent phases of development (e.g. migration of neurons or lymphocytes ) as well as in normal function. (princeton.edu)
  • In chemotaxis, individual cells, unicellular organisms, and small multicellular organisms respond to chemicals by moving closer or further away from them. (wisegeek.com)
  • In multicellular organisms, chemotaxis is critical to development as well as normal function. (wikidoc.org)
  • Chemotaxis is usually studied at a transitional phase in development, in which separate cells aggregate together by chemotaxis to cyclic-AMP, en route to forming multicellular structures. (rupress.org)
  • In the lab, chemotaxis is frequently examined in the nematode, C. elegans , which is known to migrate towards food sources in soil, but away from toxins such as heavy metals, substances with a low pH, and detergents. (jove.com)
  • Chemotaxis experiments in C. elegans have near-limitless possibilities for learning more about the cellular and genetic mechanisms of many biological processes, and may lead to a greater understanding of human biology, development, and disease. (jove.com)
  • The chemotaxis behavior of the nematode Caenorhabditis elegans raises, in simplified form, the key question of how the nervous system transforms sensory input into motor output to regulate a goal-directed response. (jneurosci.org)
  • We found that the step responses likely to underlie C. elegans chemotaxis in steep gradients are complex, with multiple phases and a nonlinear dependence on the sign and amplitude of the stimulus. (jneurosci.org)
  • Chemotaxis is a process in which cells or organisms move in response to a chemical stimulus. (jove.com)
  • Chemotaxis (from chemo- + taxis) is the movement of an organism in response to a chemical stimulus. (wikipedia.org)
  • Rectification of dysregulated CC chemokine signaling for monocyte/macrophage chemotaxis in head and neck squamous cell carcinoma patients by neem leaf glycoprotein maximizes tumor cell cytotoxicity. (thefreedictionary.com)
  • Even though intracellular signals underlying the regulation of microglia chemotaxis are still not well understood, many attempts focusing on revealing and understanding signaling pathways controlling microglia chemotaxis have been made in recent years. (pubmedcentralcanada.ca)
  • Signaling pathways reported to be involved in the regulation of microglia chemotaxis were depicted in a diagram ( Fig. 2 ). (pubmedcentralcanada.ca)
  • If they could come up with a method of inserting or producing a chemical which makes the sperm move away from the egg, that could be very non-intrusive, easy way of preventing pregnancy through chemotaxis. (wisegeek.com)
  • For example, chemotaxis is required for the movement of sperm toward an egg prior to fertilization. (jove.com)
  • Chemotaxis is a mechanism that provides directional cellular movement in response to alterations in the chemical composition of the immediate environment. (genengnews.com)
  • Temporal and spatial regulation of chemotaxis. (nih.gov)
  • Research on chemotaxis includes exploration into how small organisms move, when they respond to chemical signals, and what can interrupt these processes. (wisegeek.com)
  • Chemicals can interrupt chemotaxis by confusing or disorienting cells, leading them to make mistakes. (wisegeek.com)
  • This paper presents a qualitative analysis of a model describing the time and space dynamics of a virus which migrates driven by chemotaxis. (aimsciences.org)
  • On November 3 , 2006 , Dr. Dennis Bray of University of Cambridge was awarded the Microsoft European Science Award for his work on chemotaxis on E. coli . (wikidoc.org)
  • There are several well-established techniques, but recent technological advances enable scientists to now view chemotaxis in much finer detail. (genengnews.com)
  • Chemotaxis is also important at the cellular level. (jove.com)
  • Our goal is to understand at the neuronal level how chemosensory input regulates turning to produce chemotaxis. (jneurosci.org)
  • Repeating that process, known as chemotaxis , allows immune cells to find and demolish numerous invaders. (thefreedictionary.com)
  • Corrias L., Perthame B., Zaag H.: Global solutions of some chemotaxis and angiogenesis systems in high space dimensions. (springer.com)