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.

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)

  • The immune system uses cells like neutrophils and macrophages to detect infectious organisms and neutralize them, relying on chemotaxis to sniff out chemicals produced by these cells so it can track them down. (wisegeek.com)
  • Chemotaxis of immunological cells such as leukocytes (neutrophils, monocytes and lymphocytes) and other immune cells. (molecularstation.com)
  • Fibrin is also essential for the chemotaxis of neutrophils and macrophages that play a major role in the healing and the defense against infections. (thefreedictionary.com)
  • The type of inhibition that was observed in these in vitro assay systems was quite similar to that observed in vivo, because PT could depress chemotaxis in vitro as well as the accumulation of radiolabeled lymphocytes and neutrophils within a peripheral site of inflammation in vivo. (jimmunol.org)
  • Chemotaxis of control neutrophils towards BALF from patients with active (p=0.006) and remission WG (p=0.077) and IPF patients (p=0.001) was increased compared with normal controls. (ersjournals.com)
  • Previous investigations (22) showed that LTB4 is the strongest LT triggering inflammation induced by SMU, by having a significant effect on the chemotaxis and activation of neutrophils (4, 23). (thefreedictionary.com)
  • Pharmacological inhibition of mTOR kinase activity and AKT phosphorylation fails to affect actin polymerization and chemotaxis in both human neutrophils and dHL-60 cells. (illinois.edu)
  • The aim of our study was to assess the effect of dietary supplementation with vitamin C-rich SunGold kiwifruit on four important functions of neutrophils: chemotaxis, oxidant generation, extracellular trap formation, and apoptosis. (mdpi.com)
  • In some species (for example, herring or the ascidian Ciona) activation of motility precedes chemotaxis. (wikipedia.org)
  • The chapter includes analyses of random cell motility, directed motility up chemical gradients, cellular responses to uniform chemoattractant exposure, and the utility of fluorescent probes for chemotaxis signaling events. (nih.gov)
  • Steady gradients, linear or nonlinear, are often a useful model of the bacterial microenvironment to study chemotaxis in the limit of slow patch diffusion or fast motility of free swimming bacterial cells. (mit.edu)
  • Interestingly, cell adherence and surface hydrophobicity, biosurfactant production, motility, and chemotaxis processes are bacterial abilities that reduce the distance between the microorganisms and solid substrates, enhancing bioavailability. (springer.com)
  • We particularly focused on a motility response known as chemotaxis and developed a computer model that includes not only intracellular information processing but also motor control. (mit.edu)
  • Two molecular systems drive this process: the motility apparatus and the chemotaxis signal transduction system. (sciencechatforum.com)
  • We demonstrate that motility and chemotaxis play a crucial role in the collective behaviour - autoaggregation - of E. coli. (uni-marburg.de)
  • CheF, the protein bridging the chemotaxis signal transduction system and the motility apparatus, was recombinantly expressed, purified and subjected to X-ray data collection. (iucr.org)
  • Flagellar motility and chemotaxis by Vibrio fischeri are important behaviors mediating the colonization of its mutualistic host, the Hawaiian bobtail squid. (asm.org)
  • The genome of the squid symbiont Vibrio fischeri (strain ES114) encodes 43 predicted MCPs ( 22 , 23 ), none of which have been studied, despite the importance of chemotaxis and flagellar motility in the symbiotic lifestyle of this organism ( 24 - 28 ). (asm.org)
  • Chemotaxis is the phenomenon in which bodily cells, bacteria , and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. (princeton.edu)
  • Bacterial chemotaxis, which has been extensively studied for three decades, is the most prominent model system for signal transduction in bacteria. (nih.gov)
  • As a means of finding food sources during vegetative growth, Dictyostelium discoideum naturally chemotaxes toward chemicals released by bacteria. (nih.gov)
  • The chemotaxis signal transduction pathway allows bacteria to respond to changes in concentration of specific chemicals (ligands) by modulating their swimming behavior. (nih.gov)
  • 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. (everything2.com)
  • 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. (mit.edu)
  • Particularly, chemotaxis may enable hydrocarbon-utilizing bacteria to actively seek new substrates once they are depleted in a given contaminated area increasing their bioavailability and biodegradation. (springer.com)
  • Adadevoh JS, Triolo S, Ramsburg CA, Ford RM (2016) Chemotaxis increases the residence time of bacteria in granular media containing distributed contaminant sources. (springer.com)
  • Ford RM, Harvey RW (2007) Role of chemotaxis in the transport of bacteria through saturated porous media. (springer.com)
  • Abstract - Chemotaxis can be defined as an innate behavioural response by an organism to a directional stimulus, in which bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. (psu.edu)
  • This provides the first physiologically relevant example of collective behaviour in bacteria being driven by chemotaxis to a self-produced attractant. (uni-marburg.de)
  • In QBFO, chemotaxis operation is not performed as same as original BFO because Q-bacteria can be in quantum superposition state. (thefreedictionary.com)
  • 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. (gatech.edu)
  • Also, models of chemotaxis in both eukaryotic cells and bacteria will be discussed. (umn.edu)
  • a research group that previously found that polymorphonuclear leukocytes (PMNs) in plasma treated with the divalent cation chelating agent EDTA showed a prolonged chemotactic response, undertook a search for a tonic inhibitor of chemotaxis that might be susceptible to inhibition by this chelator. (sciencemag.org)
  • A chemotaxis assay's function is to assess whether a factor or molecule of interest has chemotactic activity on a motile cell type. (molecularstation.com)
  • On a chemotaxis model with saturated chemotactic flux. (aimsciences.org)
  • Sera from patients with depressed MNL chemotaxis contained a cell-directed chemotactic inhibitor which was heat stable (56°C, 30 min), non-dialyzable and distinct from the sulfadiazine used for topical therapy. (jimmunol.org)
  • To determine the mechanism of chemotaxis, tears were incubated with chemotactic inhibitors prior to placement on microtiter plate. (arvojournals.org)
  • This chemotactic response is mediated by the H 4 receptor, because chemotaxis toward histamine was absent in mast cells derived from H 4 receptor-deficient mice but was detected in H 3 receptor-deficient mast cells. (aspetjournals.org)
  • Family members had normal chemotaxis, and the patient's serum was capable of generating normal amounts of chemotactic factors. (annals.org)
  • This means a distinction can be made between chemotaxis and chemokinesis, and researchers are able to better control specific chemical gradients so as to understand cellular behavior under different conditions. (genengnews.com)
  • Observed cell distribution along the gradients showed good agreement with predictions from the bacterial transport equation, providing the first quantification of chemotaxis in steady nonlinear gradients. (mit.edu)
  • Bacterial chemotaxis, organism-specific biosystem Chemotaxis is the process by which cells sense chemical gradients in their environment and then move towards more favorable conditions. (nih.gov)
  • Here, we present a comprehensive characterization of the chemotaxis sensorimotor transformation in terms of the behavioral response to concentration steps experienced in steep gradients. (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 the process by which cells sense chemical gradients in their environment and then move towards more favorable conditions. (genome.jp)
  • This behavior, conferred by the chemotaxis signaling system, is used to track chemical gradients in liquid. (asm.org)
  • A paper-based invasion assay: assessing chemotaxis of cancer cells in gradients of oxygen. (sigmaaldrich.com)
  • Collective cell chemotaxis, the directed migration of cell groups along gradients of soluble chemical cues, underlies various developmental and pathological processes. (sciencemag.org)
  • Most long-range directed migration in vivo occurs by chemotaxis ( 2 , 4 - 9 ), in which cells follow gradients of soluble chemical cues. (sciencemag.org)
  • Migration to preferred environmental conditions is mediated by a behavior known as chemotaxis ( 2 ), which allows the bacterium to sense gradients of attractants and respond by controlling the directionality of the flagellar motor ( 3 ). (asm.org)
  • The results show that inhibition of either PI3-kinase or PLA2 inhibits chemotaxis in shallow cAMP gradients, whereas both enzymes must be inhibited to prevent chemotaxis in steep cAMP gradients, suggesting that PI3-kinase and PLA2 are two redundant mediators of chemotaxis. (rupress.org)
  • Directed cell migration can be guided by different types of gradients, for example chemotaxis. (aps.org)
  • Here, we first determine the chemotaxis response of Dictyostelium cells to static folic acid gradients and show that they can significantly exceed this sensitivity, responding to gradients as shallow as 0.2% across the cell body. (royalsocietypublishing.org)
  • The regulation is carried out by the chemotaxis protein, CheY. (nih.gov)
  • The dynamics of protein phosphorylation in bacterial chemotaxis. (nih.gov)
  • Its applications in biological studies include quantifying and comparing cellular and subcellular components, estimating DNA and protein concentrations, and analyzing processes like chemotaxis and cell migration. (thefreedictionary.com)
  • An insertion in accA , which encodes the periplasmic binding protein for agrocinopines A+B, abolished chemotaxis while an insertion in accC , which encodes a component of the transport system, and an insertion in accF , which encodes a function required for agrocinopine catabolism, did not affect chemotaxis to this opine. (apsnet.org)
  • The Nia1nit2 mutant with defects in genes encoding the nitrate reductase and regulatory protein NIT2 respectively was found to exhibit normal chemotaxis to nitrite. (mdpi.com)
  • The studies revealed individual elements of the phototropin-dependent signal transduction pathway involved in the blue-light-controlled change in chemotaxis mode of C. reinhardtii during gamete formation: three protein kinases, one operating against signal flux and two that promote signal transduction. (mdpi.com)
  • Treating the extract with proteinase K or chitinase significantly inhibited its ability to induce chemotaxis, thereby demonstrating that the chemoattractants were both protein and chitin. (pubmedcentralcanada.ca)
  • Sperm chemotaxis is a form of sperm guidance, in which sperm cells (spermatozoa) follow a concentration gradient of a chemoattractant secreted from the oocyte and thereby reach the oocyte. (wikipedia.org)
  • In sperm chemotaxis, the oocyte secretes a chemoattractant, which, as it diffuses away, forms a concentration gradient: a high concentration close to the egg, and a gradually lower concentration as the distance from the oocyte increases. (wikipedia.org)
  • In fact, the ability of arachidonic acid to enhance chemotaxis depended on EDTA, and pharmacological analysis suggested that this synergistic effect involved the EDTA-dependent generation of the chemoattractant leukotriene B4 (LTB4) from the added arachidonic acid. (sciencemag.org)
  • The IncuCyte ® live-cell analysis system is used to visualize the directional migration of cells across the surface and toward chemoattractant positioned in the reservoir of the plate and IncuCyte ® Chemotaxis Cell Migration image analysis software is used to quantify this migration. (news-medical.net)
  • Here, we assessed fertilization changes in the presence of a chemoattractant-digesting peptidase and used a microfluidic device coupled with a fertilization assay to determine the effect of sperm chemotaxis on individual male fertilization success in the sea urchin Lytechinus pictus . (biologists.org)
  • Sexual reproduction relies on chemotaxis to allow sperm to migrate toward an egg, following chemoattractants produced by the egg so it can complete fertilization. (wisegeek.com)
  • Under most conditions, the signaling apparatus mediating bacterial chemotaxis exhibits perfect adaptation to chemoattractants: the output is reset exactly to the prestimulus value so that the steady-state behavior of the system is independent of the concentration of a homogeneous distribution of the attractant ( 2 - 4 ). (pnas.org)
  • This talk will discuss some recent data obtained using a relatively high-throughput 96 well chemotaxis system, which has allowed us to identify chemoattractants produced by activated mast cells which recruit progenitor mast cells. (regonline.co.uk)
  • Using both an available transposon mutant collection and directed mutagenesis, we isolated mutants for 19 of these genes, and screened them for altered chemotaxis to six previously identified chemoattractants. (asm.org)
  • While chemotaxis towards volatile chemoattractants does not change significantly after conditioning with NaCl, chemotaxis towards other water-soluble attractants does decrease. (biologists.org)
  • This suggests that an altered response of a cell or a group of cells specifically involved in chemotaxis towards water-soluble chemoattractants is responsible for the behavioural alteration. (biologists.org)
  • As part of its developmental life cycle, D. discoideum chemotaxes towards cAMP. (nih.gov)
  • Chemotaxis toward different cyclic adenosine monophosphate (cAMP) concentrations was tested in Dictyostelium discoideum cell lines with deletion of specific genes together with drugs to inhibit one or all combinations of the second-messenger systems PI3-kinase, phospholipase C (PLC), phospholipase A2 (PLA2), and cytosolic Ca 2+ . (rupress.org)
  • In this study, we investigated the role of several potential second-messenger systems in D. discoideum chemotaxis. (rupress.org)
  • S. E. Malawista, A. de Boisfleury Chevance, J. van Damme, C. N. Serhan, Tonic inhibition of chemotaxis in human plasma. (sciencemag.org)
  • Although contact inhibition of locomotion and cluster confinement ( 19 , 20 ) are needed for cephalic neural crest directional movement in Xenopus and zebrafish, they are not sufficient, as collective chemotaxis toward SDF1 is essential for long-range directed movement ( 6 ). (sciencemag.org)
  • Clenbuterol, a beta-2-adrenergic agonist that increases icAMP production, demonstrated a dose dependent inhibition of chemotaxis toward equine tears. (arvojournals.org)
  • however, additional inhibition of PLA2 completely blocks chemotaxis, whereas inhibition of PI3-kinase has no effect, suggesting that all chemotaxis in plc -null cells is mediated by PLA2. (rupress.org)
  • The results show that inhibition of PI3K and PLA2 strongly reduces chemotaxis. (rupress.org)
  • 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. (mit.edu)
  • 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 use neural crest cells, a migratory embryonic stem cell population whose behavior has been likened to malignant invasion, to study collective chemotaxis in vivo. (sciencemag.org)
  • Using a capillary chemotaxis assay, we showed that, unlike wild-type V. fischeri , the vfcA mutant did not undergo chemotaxis toward serine and that expression of vfcA on a plasmid in the mutant was sufficient to restore the behavior. (asm.org)
  • A. Chertock , K. Fellner , A. Kurganov , A. Lorz and P. Markowich , Sinking, merging and stationary plumes in a coupled chemotaxis-fluid model: a high-resolution numerical approach, Journal of Fluid Mechanics , 694 (2012), 155-190. (aimsciences.org)
  • Work in Pseudomonas aeruginosa , a species that encodes 26 MCPs in strain PAO1, has characterized 9 MCPs that mediate chemotaxis toward ligands such as amino acids, trichloroethylene, and malate ( 15 - 18 ). (asm.org)
  • CCR5 plays a role in mediating leukocyte chemotaxis in response to its ligands, which include RANTES, MIP-1a, and MIP-1b. (thefreedictionary.com)
  • 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)
  • Sperm chemotaxis was demonstrated in a large number of non-mammalian species, from marine invertebrates to frogs. (wikipedia.org)
  • The molecular mechanism of sperm chemotaxis is still not fully known. (wikipedia.org)
  • 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)
  • Sperm chemotaxis, the ability of sperm to navigate towards eggs using chemical signals, has been studied for over a century, but such studies have long assumed that this phenomenon improves individual male fitness without explicit evidence to support this claim. (biologists.org)
  • These results demonstrate that sperm chemotaxis is an important contributor to individual reproductive success. (biologists.org)
  • Furthermore, the integrated standalone microfluidic gradient generator and cell-docking structure improve the control of cell migration experiment, which enables easier and more accurate chemotaxis analysis. (eurekalert.org)
  • This paper describes a simple and reusable microfluidic SlipChip device for studying bacterial chemotaxis based on free interface diffusion. (rsc.org)
  • These results suggest that CpnA plays a role in chemotaxis and adhesion and may do so by interacting with actin filaments. (mdpi.com)
  • Repeating that process, known as chemotaxis , allows immune cells to find and demolish numerous invaders. (thefreedictionary.com)
  • Bournaveas N., Calvez V., Gutiérrez S., Perthame B.: Global existence for a kinetic model of chemotaxis via dispersion and Strichartz estimates. (springer.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)
  • Chalub F.A.C.C., Markowich P.A., Perthame B., Schmeiser C.: Kinetic models for chemotaxis and their drift-diffusion limits. (springer.com)
  • Chalub F.A.C.C., Rodrigues J.F.: A class of kinetic models for chemotaxis with threshold to prevent overcrowding. (springer.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)
  • 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 cellular defect in leukocyte chemotaxis and the abnormalities in cellular immunity in this child may be important factors in her marked susceptibility to infections. (annals.org)
  • Chemotaxis (from chemo- + taxis) is the movement of an organism in response to a chemical stimulus. (wikipedia.org)
  • The substances that induce chemotaxis vary from organism to organism. (thefreedictionary.com)
  • We report here a simple form of chemotaxis plasticity in this organism: when worms are starved on plates that contain NaCl, their chemotaxis towards NaCl falls dramatically. (biologists.org)
  • In nature, chemotaxis is important for organisms to sense and move toward food sources and move away from stimuli that may be toxic or harmful. (jove.com)
  • The decrease in chemotaxis occurred slowly over 3-4 h of conditioning and returned quickly to the original level when either of the conditioning stimuli, NaCl or starvation, was removed. (biologists.org)
  • There are several well-established techniques, but recent technological advances enable scientists to now view chemotaxis in much finer detail. (genengnews.com)
  • In the present study, we screened 19 MCPs in V. fischeri ES114 and identified a single gene product that mediates chemotaxis to multiple amino acids. (asm.org)
  • Cells lacking GflB display impaired Rap1/Ras signaling and actin and myosin dynamics, resulting in defective chemotaxis. (rug.nl)
  • The patient's eosinophils had defective chemotaxis, shape changes, and F-actin reorganization against eotaxin, when compared to the controls. (dovepress.com)
  • Likewise, blocking PI3K, tyrosine kinase, p38 and p44/42 inhibited eosinophil chemotaxis to parasite extract. (pubmedcentralcanada.ca)
  • Furthermore, CCR3, CXCR4 or CXCR2 antagonists significantly inhibited eosinophil chemotaxis to the parasite extract. (pubmedcentralcanada.ca)
  • Numerous studies have demonstrated that various parasites synthesize molecules with the capacity to attract leukocytes, and products triggering eosinophil chemotaxis have been isolated from parasitic nematodes [ 12 , 13 ]. (pubmedcentralcanada.ca)
  • 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)
  • Chemotaxis is movement of small organisms and single cells in response to chemical signals in the surrounding environment. (wisegeek.com)
  • In chemotaxis, individual cells, unicellular organisms, and small multicellular organisms respond to chemicals by moving closer or further away from them. (wisegeek.com)
  • Chemicals can interrupt chemotaxis by confusing or disorienting cells, leading them to make mistakes. (wisegeek.com)
  • Chemotaxis of the cells from the upper chamber into the lower chamber can be quantified. (molecularstation.com)
  • Chemotaxis is a process in which cells or organisms move in response to a chemical stimulus. (jove.com)
  • Furthermore, the integrated cell-docking feature permits cell pre-alignment in the device before chemotaxis experiment, and therefore it can provide instant chemotaxis test result at the end of the experiment based on the final positions of the cells," says Professor Francis Lin in the Department of Physics and Astronomy at the University of Manitoba and Principal Investigator of this study. (eurekalert.org)
  • Collectively, this habitat-adapted polymicrobial community residing in the root canal has several biological and pathogenic properties, such as antigenicity, mitogenic activity, chemotaxis , enzymatic histolysis, and activation of host cells. (thefreedictionary.com)
  • The migration of cells in the microwells was monitored and accurately counted to evaluate chemotaxis. (rsc.org)
  • The term chemotaxis is used to describe the movement of organisms or cells in response to the presence of a chemical or chemical gradient, whereby the orientation or movement of the organisms or cells is influenced in a positive or negative manner by the substance exhibiting chemical properties. (peprotech.com)
  • Although both can include a number of organic and inorganic substances, the most commonly researched inducers of chemotaxis are chemokines, or cytokines secreted by cells for the purpose of driving cellular movement and activation. (peprotech.com)
  • 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)
  • Analysis of the data as a function of time revealed that patients who died generally had depressed chemotaxis immediately postburn and that their cells showed no functional improvement with time. (jimmunol.org)
  • Female sexual cells of the aquatic fungus Allomyces release the isoprenoid syrenin, a stimulus of chemotaxis of male sexual cells toward female cells. (thefreedictionary.com)
  • RacG-KO cells showed a moderate chemotaxis defect that was stronger in the RacG-V12 and RacG-N17 mutants, in part because of interference with signaling through Rac1. (asm.org)
  • cpnA − cells exhibited defects in three actin-based processes: chemotaxis, cell polarity, and adhesion. (mdpi.com)
  • Thus, in neural crest cells, collective chemotaxis works by rear-wheel drive. (sciencemag.org)
  • We asked whether cells at the group's rear ( Fig. 1A , dotted rectangle) contribute to collective cell chemotaxis. (sciencemag.org)
  • To investigate the mechanism of collective chemotaxis ex vivo and in vivo, we studied Xenopus and zebrafish cranial neural crest cells, an embryonic cell population that undergoes collective cell migration ( 6 , 16 ) in a manner similar to cancer cells ( 17 ), unlike neural crest cells of other species or those in the trunk, where less is known about the collectiveness ( 18 ). (sciencemag.org)
  • Depletion of mTORC2, not mTORC1, abolishes fMLP-induced actin polymerization and chemotaxis in dHL-60 cells. (illinois.edu)
  • Unlike vegetative cells and noncompetent pregametes, mature gametes did not show chemotaxis to nitrite. (mdpi.com)
  • These esotactic surfaces have more guidance cues for cells than planar 2D cultures and can disrupt other guidance types like chemotaxis. (aps.org)
  • Levamisole produced dose-dependent stimulation of chemotaxis, a greater effect found with the patients cells. (bmj.com)
  • While our proposed QBFO takes a new representation of a bacterium, and a new quantum chemotaxis operator and a new quantum elimination-dispersal, which were not considered in these earlier studies. (thefreedictionary.com)
  • Monitoring chemotaxis toward cAMP and folate allows the determination of signaling events required for sensing a chemical gradient and moving in a directed, persistent manner up the gradient. (nih.gov)
  • We further found that individual male differences in chemotaxis to a well-defined gradient of attractant correlate with individual male differences in fertilization success. (biologists.org)
  • Chemotaxis is achieved by coupling gradient sensing to basic cell movement. (rupress.org)
  • Two important questions on chemotaxis are (1) What is the compass detecting the cAMP gradient? (rupress.org)
  • Science Buddies , 12 Jan. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/MicroBio_p028/microbiology/chemotaxis-slime-mold. (sciencebuddies.org)
  • This second edition expands on the first edition with new chapters describing methods for studying cell movement, molecular components involved in chemotaxis, spatiotemporal dynamics of signaling components, and quantitative modeling, as well as several updated chapters from the first edition. (springer.com)
  • Chemotaxis: Methods and Protocols, Second Edition also contains microscopy procedures for studying breast cancer cell migration, tumor cell invasion in vivo, and axon guidance. (springer.com)
  • This chapter describes protocols for using Dictyostelium to understand the cell biology behind and the signaling events necessary for eukaryotic amoeboid chemotaxis. (nih.gov)
  • Chemotaxis is the ability of a factor to cause the migration of a cell. (molecularstation.com)
  • Chemotaxis is one of the most basic cell physiological responses. (wikidoc.org)
  • We further show that this enhancement is due to the interspecies signalling that is mediated by AI-2, which enables E. coli to maintain activity of its quorum sensing system and promotes its chemotaxis-dependent aggregation at lower cell densities. (uni-marburg.de)
  • Chemotaxis is a complex response of a cell to an external stimulus. (currentprotocols.com)
  • In summary, a 33-day course of maraviroc, an inhibitor of T-cell chemotaxis, appeared to reduce the incidence of acute visceral GVHD without major adverse events. (natap.org)
  • This contractility is polarized during collective cell chemotaxis: It is inhibited at the front but persists at the rear of the cell cluster. (sciencemag.org)
  • Chemotaxis is a pivotal response of many cell types to external spatial cues. (rupress.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)
  • Nevertheless, our work shows that, by promoting aggregative behaviour via chemotaxis, AI-2 plays a true signalling function in E. coli. (uni-marburg.de)
  • However, as more diverse bacterial species have been studied, we have learned that bacterial chemotaxis is frequently more complex than the E. coli paradigm ( 10 , 11 ). (asm.org)
  • VcAer2 can serve as a promising alternative to E. coli Aer or PaAer2 for investigating PAS-mediated chemotaxis. (cornell.edu)
  • By the use of chambers containing two compartments with an interposed micropore filter, chemotaxis of polymorphonuclear leukocytes (PMN's) in vitro was studied employing various agents that fixed serum complement (C'). Antigen-antibody complexes, zymosan, and aggregated human gamma globulin, in the presence of fresh rabbit, guinea pig, or mouse serum resulted in the migration of PMN's through the micropore filter. (rupress.org)
  • The authors thus conclude that oleic acid represents a tonic inhibitor of PMN chemotaxis that could perhaps be manipulated for anti-inflammatory purposes. (sciencemag.org)
  • These studies document that depressed MNL chemotaxis occurs as a consequence of serious thermal trauma, that this defect may be due to a serum inhibitor and that abnormal MNL chemotaxis may contribute to septic morbidity and mortality in severely burned patients. (jimmunol.org)
  • Elevation of intracellular cAMP (icAMP) with rolipram, a selective phosphodiesterase 4 inhibitor, did not significantly affect equine PMN chemotaxis when tested alone. (arvojournals.org)
  • In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis . (princeton.edu)
  • Thus CheY phosphorylation appears to be involved in controlling both the excitation and adaptation mechanisms of bacterial chemotaxis. (nih.gov)
  • 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)
  • Chemotaxis is called positive if movement is in the direction of a higher concentration of the chemical in question, and negative if the direction is opposite. (princeton.edu)
  • Chemotaxis is a mechanism that provides directional cellular movement in response to alterations in the chemical composition of the immediate environment. (genengnews.com)
  • The movement of insects in response to pheromones may also be regarded as chemotaxis. (thefreedictionary.com)
  • Even in the human pathogen Vibrio cholerae , only 3 of up to 45 putative MCPs, contributing to aerotaxis, amino acid chemotaxis, and chemotaxis toward the chitin-derived sugars N -acetylglucosamine (GlcNAc) and N , N ′-diacetylchitobiose [(GlcNAc) 2 ] have been described ( 19 - 21 ). (asm.org)
  • In our work we propose a family of stable (even at times near blow up) and highly accurate numerical methods, based on interior penalty discontinuous Galerkin schemes (IPDG) for the Keller-Segel chemotaxis model with parabolic-parabolic coupling. (gatech.edu)
  • TTP LabTech offers a high throughput solution for chemotaxis research using the Acumen eX3 microplate cytometer and the iuvo Chemotaxis Assay Plate from BellBrook Labs. (thefreedictionary.com)
  • In this paper, we study a variation of the equations of a chemotaxis kinetic model and investigate it in one dimension. (springer.com)
  • M. Braukhoff , Global (weak) solution of the chemotaxis-Navier-Stokes equations with non-homogeneous boundary conditions and logistic growth, Annales de l'Institut Henri Poincaré (C) Non Linear Analysis , 34 (2017), 1013-1039. (aimsciences.org)
  • H. J. Choe and B. Lkhagvasuren , Global existence result for chemotaxis Navier-Stokes equations in the critical Besov spaces, Journal of Mathematical Analysis and Applications , 446 (2017), 1415-1426. (aimsciences.org)