chemotaxis


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Related to chemotaxis: geotaxis, positive chemotaxis

chemotaxis:

see taxistaxis
, movement of animals either toward or away from a stimulus, such as light (phototaxis), heat (thermotaxis), chemicals (chemotaxis), gravity (geotaxis), and touch (thigmotaxis). The turning movements of plants in response to stimuli are called tropisms.
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Chemotaxis

 

the movement of cells (zoospores, spermatozoids, leukocytes) and freely moving plants and protozoans in response to chemical stimuli. Positive chemotaxis is movement toward the source of the chemical stimulus (along the chemical concentration gradient in air or water); negative chemotaxis is movement away from the source. The phenomenon is known to exist in a number of microorganisms and invertebrates. The movement of insects in response to pheromones may also be regarded as chemotaxis.

The substances that induce chemotaxis vary from organism to organism. For example, cyclic adenosine monophosphate is an aggregating substance for soil myxomycetes of the genus Dictyostelium. Female sexual cells of the aquatic fungus Allomyces release the isoprenoid syrenin, a stimulus of chemotaxis of male sexual cells toward female cells. The mechanism by which a chemical signal is sensed (chemoreception) and the pathway to the corresponding physiological reaction, that is, oriented movement, are not thoroughly understood. Chemotaxis plays a part in the search for food, in fertilization in higher plants and animals, and in phagocytosis.

REFERENCES

Behaviour of Microorganisms. London-New York, 1973.
Chemotaxis: Its Biology and Biochemistry. Edited by E. Sorkin. Basel, 1974.

chemotaxis

[‚kē·mō′tak·səs]
(biology)
The orientation or movement of a motile organism with reference to a chemical agent.
References in periodicals archive ?
Sperm chemotaxis in the hydromedusae: species specificity and sperm behavior.
Role of chemotaxis in the transport of bacteria through staturated porous media.
In particular, PdUC combines different concepts including a chemotaxis metaheuristic, a local particle swarm optimization (PSO), and an Adaptive Spiralling technique, to create an algorithm able to quickly search for hotspots having high pollution values, and to cover the surrounding area as well, thereby obtaining a complete and detailed pollution map of the target region.
Supposing that [P.sup.B.sub.c][(m).sub.value] is the fitness value of the bacterial population after performing the chemotaxis operator, which can be expressed as follows:
Caption: Figure 4: Cell migration was examined in imDCs infected with Ad.EGFP, Ad.CCR7, Ad.BTLA, or Ad.CCR7 + BTLA with in vitro chemotaxis assays.
Effects of sepsis on neutrophil chemotaxis. Curr Opin Hematol 2010;17:18-24.
Increased expression of eotaxin in bronchoalveolar lavage and airways of asthmatics contributes to the chemotaxis of eosinophils to the site of inflammation.
[sup][4] To assess the effect of PDE4 inhibition on chemotaxis, splenic T cells were treated with vehicle (DMSO) or rolipram (10 [micro]M) for 20-30 min before transferring to the upper chamber.
However, according to mathematical analysis in [10], the chemotaxis employed by the classical BFO usually results in sustained oscillation, especially on flat fitness landscapes, when a bacterium cell is close to the optima.
Monocyte chemotactic function was tested using a 12-well Transwell chamber (Beijing Lab Scientific Company, China) that was mainly composed as follows: the top plate with the upper side, the chemotaxis membrane in the middle, and the lower plate with the lower side, forming the upper and lower chambers, respectively.
Additionally, pretreatment of PMN cells with EpiCor resulted in a reduction in migration toward the inflammatory chemokine LTB4 (also known as chemotaxis), which was also statistically significant over a wide dose range.
Four general processes of E.coil foraging mechanism are chemotaxis swarming reproduction and elimination and dispersal events.