Chemotaxis is a kind of taxis, in which bodily 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 (for example, glucose) by swimming towards the highest concentration of food molecules, or to flee from poisons (for example, phenol). In multicellular organisms, chemotaxis is critical to development as well as normal function. In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. A taxis (plural taxes, pronounced takseez) is an innate behavioral response by an organism (or cell) to a directional stimulus (a stimulus from a particular direction) whereby an organism moves (orientation movement) either towards (positive taxis) or away from (negative taxis) the stimulus. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Multicellular organisms are those organisms containing more than one cell, and having differentiated cells that perform specialized functions. ... Glucose (Glc), a monosaccharide (or simple sugar), is one of the most important carbohydrates in biology. ... The skull and crossbones symbol traditionally used to label a poisonous substance. ... Phenol, also known under an older name of carbolic acid, is a colorless crystalline solid with a typical sweet tarry odor. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ...

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.

History of chemotaxis research

Milestones of chemotaxis research

Although migration of cells was detected from the early days of the development of microscopy (Leeuwenhoek), erudite description of chemotaxis was first made by T.W. Engelmann (1881) and W.F. Pfeffer (1884) in bacteria and H.S. Jennings (1906) in ciliates. The Nobel prize winner E. Metchnikoff also contributed to the study of the field with investigations of the process as an initial step of phagocytosis. The significance of chemotaxis in biology and clinical pathology was widely accepted in the 1930's. The most fundamental definitions belonging to the phenomenon were also drafted by this time. The most important aspects in quality control of chemotaxis assays were described by H. Harris in the 1950's. In the 1960s and 1970s, the revolution of modern cell biology and biochemistry provided a series of novel techniques which became available to investigate the migratory responder cells and subcellular fractions responsible for chemotactic activity. The pioneering works of J. Adler represented a significant turning point in understanding the whole process of intracellular signal transduction of bacteria.^[1] Image File history File links Download high-resolution version (960x720, 169 KB) Summary Author: Kohidai, L.; Source: Own; Date: 2006. ... Image File history File links Download high-resolution version (960x720, 169 KB) Summary Author: Kohidai, L.; Source: Own; Date: 2006. ... Anton von Leeuwenhoek Anton van Leeuwenhoek (October 24, 1632 - August 26, 1723) was a tradesman and scientist from Delft, in the Netherlands. ... Look up Pfeffer in Wiktionary, the free dictionary. ... Classes Karyorelictea Heterotrichea Spirotrichea Litostomatea Phyllopharyngea Nassophorea Colpodea Prostomatea Oligohymenophorea Plagiopylea See text for subclasses. ... Elias Metchnikoff (Ilya Ilyich Mechnikov) was born in 1845, in a what is now Ukraine. ... Phagocytos Headline text is (literally cell-eating) is a form of endocytosis wherein large particles are enveloped by the cell membrane of a (usually larger) cell and internalized to form a phagosome, or food vacuole. ... Chemotaxis assays are experimental tools for evaluation of chemotactic ability of prokaryotic or eukaryotic cells. ...

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. ^[2][3] November 3 is the 307th day of the year (308th in leap years) in the Gregorian Calendar, with 58 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... Dr. Dennis Bray is an active emeritus professor at University of Cambridge. ... The University of Cambridge, located in Cambridge, England, is the second-oldest university in the English-speaking world. ... The Microsoft European Science Award (or European Science Award or Microsoft Award) is an award/prize given by the Royal Society in London. ... Binomial name Escherichia coli T. Escherich, 1885 Low-temperature electron micrograph of a cluster of bacteria, magnified 10,000 times. ...

Phylogeny and chemotactic signalling

Chemotaxis is one of the most basic cell physiological responses. Development of receptor systems for the detection of harmful and favorable substances in the environment was most essential to unicellular organisms from the very early stages of phylogeny. Comprehensive analysis of chemotactic activity of the eukaryotic protozoon Tetrahymena pyriformis and consensus sequences of appearance of amino acids in the primordial soup suggest that there was a good correlation between the chemotactic character of these relative simple organic molecules and their development on the Earth. In this way the earliest molecules are suggested to be highly chemoattractant (e.g. Gly, Glu, Pro), while latter ones are thought to be strongly chemorepellent (e.g. Tyr, Trp, Phe) amino acids ^[4]. In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Species T hegewischi Tetrahymena are non-pathogenic free-living ciliate protozoa. ... In molecular biology and bioinformatics, a consensus sequence is a way of representing the results of a multiple sequence alignment, where related sequences are compared to each other, and similar functional sequence motifs are found. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... The primordial sea, or primordial ocean, is a term applied collectively to the oceans of the earth at a time early in its history. ... Inorganic or organic substances possessing chemotaxis inducer effect in motile cells. ... This is an article about Glycine, the amino acid. ... Glu Mobile (formerly Sorrent, Inc. ... The Latin conjunction and prefix pro means for and frequently designates an advantage. ... Týr, depicted here with both hands intact, is identified with Mars in this illustration from an 18th century Icelandic manuscript. ... TRP is a TLA which may stand for: Taxpayers for Responsible Planning Teacher recruitment program Technology Reinvestment Program Telecom Research Project Temperature reference probe Temporal Resolution Prover Temporary registration permit The Railroad Press The Readers Place The Resource Partnership (trp. ... The amino acid Phenylalanine exists in two forms, the D- and L- forms. ...

Bacterial chemotaxis

Some bacteria, such as E. coli, have several flagella per cell (4-10 typically). These can rotate in two ways : This article does not cite its references or sources. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ... A flagellum (plural, flagella) is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about. ...

1. Counter-clockwise rotation aligns the flagella into a single rotating bundle, causing the bacterium to swim in a straight line.
2. Clockwise rotation breaks the flagella bundle apart such that each flagellum points in a different direction, causing the bacterium to tumble in place.

The directions of rotation are given for an observer outside the cell looking down the flagella toward the cell.

Image File history File links ChtxCCW_CW.png‎ Summary Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Behavior

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 mathematics and physics, a random walk, sometimes called a drunkards walk, is a formalisation of the intuitive idea of taking successive steps, each in a random direction. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ... This article or section does not cite its references or sources. ...

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 longer before tumbling. If it is moving in the wrong direction, it will tumble sooner and try a new direction at random. In other words, bacteria like E. coli use temporal sensing to decide whether life is getting better or worse. In this way, it finds the location with the highest concentration of attractant (usually the source) quite well. Even under very high concentrations, it can still distinguish very small differences in concentration. Fleeing from a repellent works with the same efficiency. Horizontal line (use sparingly)d grade for the grade or gradient of roads and other geographic features. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ...

It seems remarkable that this purposeful random walk is a result of simply choosing between two methods of random movement; namely tumbling and straight swimming. In fact, chemotactic responses such as forgetting direction and choosing movements resemble the decision-making abilities of higher lifeforms with brains that process sensory data. In cell biology, a biased random walk enables bacteria to source for food and flee from harm. ...

The helical nature of the individual flagellar filament is critical for this movement to occur. As such, the protein that makes up the flagellar filament, flagellin, is quite similar among all flagellated bacteria. Vertebrates seem to have taken advantage of this fact by possessing an immune receptor (TLR5) designed to recognize this conserved protein. Flagellin is a protein that arranges itself in a hollow cylinder to form the filament in bacterial flagellum. ... The three letter abbreviation TLR can stand for toll-like receptors, a group of proteins constituting an important part of the immune system twin-lens reflex cameras, photo cameras with two lenses A motorcycle with a 998cc v-twin engine manufactured by Suzuki. ...

As in many instances in biology, there are bacteria that do not follow this rule. Many bacteria, such as Vibrio, are monoflagellated and have a single flagellum at one pole of the cell. Their method of chemotaxis is different. Others possess a single flagellum that is kept inside the cell wall. These bacteria move by spinning the whole cell, which is shaped like a corkscrew.^[5]

Signal transduction

Chemical gradients are sensed through multiple transmembrane receptors, called methyl accepting chemotaxis proteins (MCPs), which vary in the molecules that they detect. These receptors may bind attractants or repellents directly or indirectly through interaction with proteins of periplasmatic space. The signals from these receptors are transmitted across the plasma membrane into the cytosol, where Che proteins are activated. The Che proteins alter the tumbling frequency, and alter the receptors. Transmembrane receptors are integral membrane proteins, which reside and operate typically within a cells plasma membrane, but also in the membranes of some subcellular compartments and organelles. ... The periplasmic space is the space seen between the plasma membrane and the outer membrane in the gram-negative bacteria. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... ÃThe cytosol (as opposed fatty cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ...

Image File history File links ChtxAspRec. ...

Flagellum regulation

The proteins CheW and CheA bind to the receptor. The activation of the receptor by an external stimulus causes autophosphorylation in the histidine kinase, CheA, at a single highly conserved histidine residue. CheA in turn transfers phosphoryl groups to conserved aspartate residues in the response regulators CheB and CheY. This mechanism of signal transduction is called a 'Two Component System' and is a common form of signal transduction in bacteria. CheY induces tumbling by interacting with the flagellar switch protein FliM, inducing a change from counter-clockwise to clockwise rotation of the flagellum. Change in the rotation state of a single flagellum can disrupt the entire flagella bundle and cause a tumble. Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule. ...

Receptor regulation

CheB, when activated by CheA, acts as a methylesterase, removing methyl groups from glutamate residues on the cytosolic side of the receptor. It works antagonistically with CheR, a methyltransferase, which adds methyl residues to the same glutamate residues. The more methyl residues are attached to the receptor, the more sensitive the receptor. As the signal from the receptor induces demethylation of the receptor in a feedback loop, the system is continuously adjusted to environmental chemical levels, remaining sensitive for small changes even under extreme chemical concentrations. This regulation allows the bacterium to 'remember' chemical concentrations from the recent past and compare them to those it is currently experiencing, thus 'know' whether it is traveling up or down a gradient. However, the methylation system alone cannot account for the wide range of sensitivity that bacteria have to chemical gradients. Additional regulatory mechanisms such as receptor clustering and receptor-receptor interactions also modulate the signalling pathway. An esterase is an hydrolase enzyme that splits esters into a acid and an alcohol in a chemical reaction with water called hydrolysis. ... Glutamate is the anion of glutamic acid. ... ÃThe cytosol (as opposed fatty cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ... In biochemistry, a transferase is an enzyme that catalyzes the transfer of a functional group (e. ... In cybernetics and control theory, feedback is a process whereby some proportion or in general, function, of the output signal of a system is passed (fed back) to the input. ...

Image File history File links Chtxbactsign1. ...

Eukaryotic chemotaxis

The mechanism by which eukaryotic cells chemotax is quite different from that in bacteria; however, sensing of chemical gradients is still a crucial step in the process. Due to their size, prokaryotes cannot detect effective concentration gradients, therefore these cells scan and evaluate their environment by a constant swimming (consecutive steps of straight swims and tumbles). In contrast to prokaryotes, the size of eukaryotic cells allows for the possibility of detecting gradients, which results in a dynamic and polarized distribution of receptors. Induction of these receptors by chemoattractants or chemorepellents results in migration towards or away from the chemotactic substance. Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ...

Levels of receptors, intracellular signalling pathways and the effector mechanisms all represent diverse, eukaryotic type components. In eukaryotic unicellular cells, ameboid movement and cilium or the eukaryotic flagellum are the main effectors (e.g. Amoeba or Tetrahymena). Some eukaryotic cells of higher vertebrate origin, such as immune cells also move to where they need to be. Besides immune competent cells (granulocyte, monocyte, lymphocyte) a large group of cells - considered previously to be fixed into tissues - are also motile in special physiological (e.g. mast cell, fibroblast, endothelial cells)or pathological conditions (e.g. metastases). Chemotaxis has high significance in the early phases of embryogenesis as development of germ layers is guided by gradients of signal molecules. Image File history File links Chtxbaceukkl1. ... Amoeba is a genus of protozoa that moves by means of temporary projections called pseudopods, and is well-known as a representative unicellular organism. ... Species T hegewischi Tetrahymena are non-pathogenic free-living ciliate protozoa. ... ... Granulocytes are a category of white blood cells characterised by the presence of granules in their cytoplasm. ... Monocyte A monocyte is a leukocyte, part of the human bodys immune system that protect against blood-borne pathogens and move quickly to sites of infection in the tissues. ... A lymphocyte is a type of white blood cell involved in the human bodys immune system. ... Mast cells A mast cell (or mastocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. ... A fibroblast is a cell that makes the structural fibers and ground substance of connective tissue. ... The endothelium is the layer of thin, flat cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ... Embryogenesis is the process by which the embryo is formed and develops. ... Organs derived from each germ layer. ...

Motility

Unlike motility in bacterial chemotaxis, the mechanism by which eukaryotic cells physically move is unclear. There appear to be mechanisms by which an external chemotactic gradient is sensed and turned into an intracellular PIP3 gradient, which results in a gradient in the activation of signaling pathway culminating in the polymerisation of actin filaments. The growing distal end of actin filaments develops connections with the internal surface of the plasma membrane via different sets of peptides and results in the formation of pseudopods. Cilium of eukaryotic cells can also result in chemotaxis, while in this case it is mainly a Ca²⁺ dependent induction of the microtubular system of the basal body and the 9x2+2 microtubules stroke of cilia. The orchestered beating of hundreds of cilia is synchronized by a submembranous system built between basal bodies. The details of the signaling pathways are still not totally clear. Phosphatidylinositol (3,4,5)-trisphosphate commonly abbreviated to PIP3 is the product of the class I phosphoinositide 3-kinases (PI 3-kinases) activity on PI(4,5)P2. ... Polymerization is the formation of long, repeating organic polymer chains. ... G-Actin (PDB code: 1j6z). ... Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. ... cross-section of two motile cilia, showing the 9+2 structure A cilium (plural cilia) or undulipodium (pl. ... A basal body is a short cylindrical array of microtubules plus their associated proteins found at the base of a eukaryotic cell cilium or flagellum. ... Microtubules are protein structures found within cells. ...

Chemotaxis related migratory responses

Although chemotaxis is the most frequently studied form of migration there are several other forms of locomotion on the cellular level.

• Chemokinesis is also induced by molecules of the liquid phase of the surrounding environment; however, the response elicited is a not vectorial, random taxis. Neither amplitude nor frequency of motion has characteristic, directional components as this behaviour provides more scanning of the environment than migration between two distinct points.
• In haptotaxis the gradient of the chemoattractant is expressed or bound on a surface, in contrast to the classical way of chemotaxis when the gradient develops in a soluble space. The main biologically active haptotactic surface is the extracellular matrix (ECM); the presence of bound ligands is responsible for induction of transendothelial migration and angiogenesis.
• Necrotaxis embodies a special type of chemotaxis when the chemoattractant molecules are released from necrotic or apoptotic cells. Depending on the chemical character of released substances necrotaxis can accumulate or repel cells, which underlines the pathophysiological significance of this phenomenon.

Horizontal line (use sparingly)d grade for the grade or gradient of roads and other geographic features. ... In biology, extracellular matrix (ECM) is any material part of a tissue that is not part of any cell. ... In chemistry, a ligand is an atom, ion or functional group that is bonded to one or more central atoms or ions, usually metals generally through co-ordinate covalent bond. ... Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. ... A cell undergoing apoptosis. ... Image File history File links Download high-resolution version (960x720, 37 KB) Summary Author:Kohidai, L. Source: Own; Date: 2001; Title: Chemotaxis related migratory responses Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Receptors

For the most part, eukaryotic cells sense the presence of chemotactic stimuli though the use of 7-transmembrane (or serpentine) heterotrimeric G-protein coupled receptors. This class of receptors is huge, representing a significant portion of the genome. Some members of this gene superfamily are used in eyesight (rhodopsins) as well as in olfaction (smelling). The main classes of professional chemotaxis receptors are triggered by formyl peptides - formyl peptide receptors (FPR), chemokines - chemokine receptors (CCR or CXCR) and leukotrienes - leukotriene receptors (BLT); however, induction of a wide set of membrane receptors (e.g. amino acids, insulin, vasoactive peptides) also elicit migration of the cell. G-proteins, short for guanine nucleotide binding proteins, are a family of proteins involved in second messenger cascades. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Chemokines are a class of chemotactic cytokines, or small secreted protein signals. ... Leukotrienes are autocrine and paracrine eicosanoid lipid mediators derived from arachidonic acid by 5-lipoxygenase. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... It has been suggested that Oral insulin be merged into this article or section. ...

Chemotactic selection

While some chemotaxis receptors are expressed in the surface membrane with long-term characteristics as they are determined genetically, others have short-term dynamics as they are assembled ad hoc in the presence of the ligand. The diverse features of the chemotaxis receptors and ligands allows for the possibility of selecting chemotactic responder cells with a simple chemotaxis assay. By chemotactic selection we can determine whether a still uncharacterized molecule acts via the long- or the short-term receptor pathway. The term chemotactic selection is also used to designate a technique which separates eukaryotic or prokaryotic cells according to their chemotactic respnsiveness to selector ligands.^[6] Chemotaxis receptors are expressed in the surface membrane with diverse dynamics, some of them have long-term characteristics as they are determined genetically, others have short-term moiety as their assembly is induced ad hoc in the presence of the ligand. ...

Image File history File links Download high-resolution version (960x720, 10 KB) |Author:Kohidai, L. | Source: Own | Date: 2000 | Title: Chemotactic selection| File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Chemotactic ligands

The number of molecules capable of eliciting chemotactic responses is relatively high, and we can distinguish primary and secondary chemotactic molecules. The main groups of the primary ligands are as follows:

• Formyl peptides are di-, tri-, tetrapeptides of bacterial origin (see formyl group on the N terminus of the peptide). They are released from bacteria in vivo or after decomposition of the cell. A typical member of this group is the N-formyl methyonyl-leucyl-phenylalanine (fMLF or fMLP in references). The bacterial origin fMLF as a key component of inflammation has characteristic chemoattractant effects in neutrophil granulocytes and monocytes.
• Complement 3a (C3a) and complement 5a (C5a) are intermediate products of complement cascade. Their synthesis is joined to the three alternative pathways (classical, lectin dependent and alternative) of complement activation by a convertase enzyme. The main target cells of these derivaties are neutrophil garnulocytes and monocytes as well.
• Chemokines belong to a special class of cytokines. Their groups (C, CC, CXC, CX₃C chemokines) represent not only structurally related molecules with a special arrangement of disulfide bridges, but their target cell specificity is also diverse: CC chemokines are acting on monocytes (e.g. RANTES), CXC chemokines are neutrophil granulocyte specific (e.g. IL-8).

Investigations of the three-dimensional structures of chemokines proved that a characteristic composition of beta-sheets and an alpha helix provides expression of sequences required for interaction with the chemokine receptors. Formation of dimers and their increased biological acitvity was demonstrated by crystallography of several chemokines e.g. IL-8. C5a is a protein fragment released from complement component C5. ... Chemokines are a class of chemotactic cytokines, or small secreted protein signals. ... Cytokines are small protein molecules that are the core of communication between immune system cells, and even between immune system cells and cells belonging to other tissue types. ... Regulated upon activation, normal T-cell expressed, and presumably secreted or RANTES is an 8kDa protein classified as a chemotactic cytokine or chemokine. ... Interleukin-8 (IL-8) is a chemokine produced by macrophages and other cell types such as epithelial cells. ... Image File history File links ChtxChemokineStruct. ...

• Leukotrienes belong to the group eicosanoids. They are significant lipid mediators of the arachidonic acid cascade converted by 5-lipoxigenase. Their predominant member is leukotriene B4 (LTB4) which elicits adhesion, chemotaxis and aggregation of leukocytes. The characteristic chemoattractant effect of LTB4 is induced via G-protein linked seven-transmembrane spanning leukotriene receptors which are highly expressed in inflammation and allergy.

Image File history File links Download high-resolution version (960x720, 20 KB) Summary Author: Kohidai, L.; Source: Own; Date: 1997; Title: Three-dimensional structure of chemokines Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Leukotrienes are autocrine and paracrine eicosanoid lipid mediators derived from arachidonic acid by 5-lipoxygenase. ... In biochemistry, eicosanoids are a class of oxygenated hydrophobic hormones that largely function as paracrine mediators. ... Inflammation is the first response of the immune system to infection or irritation and may be referred to as the innate cascade. ... An allergy can refer to several kinds of immune reactions including Type I hypersensitivity in which a persons body is hypersensitised and develops IgE type antibodies to typical proteins. ...

Chemotactic range fitting (CRF)

Chemotactic responses elicited by the ligand-receptor interactions are distinguished generally upon the optimal effective concentration(s) of the ligand. Nevertheless, correlation of the amplitude elicited and ratio of the responder cells compared to the total number are also characteristic features of the chemotactic signaling. Investigations of ligand families (e.g. amino acids or oligo peptides) proved that there is a fitting of ranges (amplitudes; number of responder cells) and chemotactic activities: chemoattractant moiety is accompanied by wide ranges, while chemorepellent character by narrow ranges.

Image File history File links Download high-resolution version (960x720, 8 KB) Summary Author: Kohidai, L.; Source: Own; Date: 2005; Title: Chemotactic range fitting Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Clinical significance

A changed migratory potential of cells has relatively high importance in the development of several clinical symptoms and syndromes. Altered chemotactic activity of extracellular (e.g. Escherichia coli) or intracellular (e.g. Listeria monocytogenes) pathogens itself represents a significant clinical target. Modification of endogenous chemotactic ability of these microorganisms by pharmaceutical agents can decrease or inhibit the ratio of infections or spreading of infectious diseases. Apart from infections, there are some other diseases where impaired chemotaxis is the primary ethiological factor, as in Chediak-Higashi syndrome where giant intracellular vesicles inhibit normal migration of cells. Binomial name Escherichia coli T. Escherich, 1885 Low-temperature electron micrograph of a cluster of bacteria, magnified 10,000 times. ... Binomial name Listeria monocytogenes Murray , 1926 Listeria monocytogenes is a Gram-positive bacterium, in the division Firmicutes, named for Joseph Lister. ... Chédiak-Higashi syndrome is a rare childhood autosomal recessive disorder that affects multiple systems of the body. ...

Inflammation is the first response of the immune system to infection or irritation and may be referred to as the innate cascade. ... Acquired Immune Deficiency Syndrome (AIDS or Aids) is a collection of symptoms and infections in humans resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV). ... Chédiak-Higashi syndrome is a rare childhood autosomal recessive disorder that affects multiple systems of the body. ... Kartagener syndrome also known as Primary Ciliary Dyskinesia or immobile ciliary syndrome is a rare autosomal recessive genetic disorder caused by a defect in the action of cilia lining the respiratory tract. ... Arthritis (from Greek arthro-, joint + -itis, inflammation; plural: arthritides) is a group of conditions where there is damage caused to the joints of the body. ... Periodontal disease is the name for bacterial infections of the gums in the mouth. ... Reperfusion injury refers to damage to tissue caused when blood supply returns to the tissue after a period of ischemia. ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ... Infertility is the inability to naturally conceive, carry or deliver a healthy child. ... Fibrous asbestos on muscovite Asbestos Asbestos Asbestos (a misapplication of Latin: asbestos quicklime from Greek : a, not and sbestos, extinguishable) describes any of a group of minerals that can be fibrous, many of which are metamorphic and are hydrous magnesium silicates. ... Benzopyrene, C20H12, is a five-ring polycyclic aromatic hydrocarbon that is mutagenic and highly carcinogenic. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ... For other uses, see Ozone (disambiguation). ...

Measurement of chemotaxis

A wide range of techniques is available to evaluate chemotactic activity of cells or the chemoattractant and chemorepellent character of ligands. The basic requirements of the measurement are as follows:

• concentration gradients can develop relatively fast and persist for a long time in the system
• chemotactic and chemokinetic activities are distinguished
• migration of cells is free towards and away on the axis of the concentration gradient
• detected responses are the results of active migration of cells

Despite the fact that an ideal chemotaxis assay is still not available, there are several protocols and pieces of equipment which offer good correspondence with the conditions described above. The most commonly used are: Chemotaxis assays are experimental tools for evaluation of chemotactic ability of prokaryotic or eukaryotic cells. ...

• Agar plate assays

E.g. PP-chamber

• Two-chamber techniques

E.g. Boyden-chamber - Zigmond chamber - Dunn chambers - Multi-well chambers - Capillary techniques

• Others

E.g. T-maze technique - Opalescence technique - Orientation assays

(A more detailed chapter you can find under Chemotaxis assay) Chemotaxis assays are experimental tools for evaluation of chemotactic ability of prokaryotic or eukaryotic cells. ...

References

November 6 is the 310th day of the year (311th in leap years) in the Gregorian Calendar, with 55 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... November 6 is the 310th day of the year (311th in leap years) in the Gregorian Calendar, with 55 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ...

External links

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Chemotaxis

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Chemotaxis

• Chemotaxis
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