Saturday, October 30, 2010

Another layer on the history of information: quorum sensing

I've recently led to a video of the Conference on the phenomenon of quorum sensing, the mechanism by which bacteria communicate with each other to determine the density of the population of micro-organisms their own kind for their proximal environment. Bonnie Bassler, speaker in this video, accomplished a masterful work of portrait pretty technical concepts and ideas to a lay audience.

The purpose of quorum sensing is essentially to ensure that sufficient number of cell of a given species is present prior to commencing a response that requires population density exceeds a certain threshold.A single bacterial cell secrete a toxin in a eukaryotic organism is not likely to host any damage would be waste ressources.Si, however, all cells in a large population bacteria coordinate the expression of the toxin, toxin is more likely to have the desired effect.

Each species which employs the detection of quorum, which includes most of gram-negative bacteria and also a few bacteria Gram-positive - summarizes molecule small signaling (technically called an "autoinducer"), which distributes freely across the cell membrane. Autoinducers are specific to each species, which means that each cell of the same species is the same molecule.This means that the autoinducer is present in concentrations in the cell when there are multiple cells of the same species to proximité.à inside the cell, the autoinducer binds Activator protein that is specific to this particular molecule and signals and bacteria to begin transcription of specific genes. As shown in the video, there is also evidence of a common autoinducer that is shared between several species of bacteria as a "classic language".

Integrated video discusses the elucidation of this process and its application in the regulation of the light-emitting bioluminescent bacteria (in this case, the marine bacterium Aliivibro fischeri). The light of the results of the action of the enzyme luciferase (if good name!).An Activator protein called LuxR, is responsible for controlling operons lux, which are in turn responsible for luminescence protein transcription. These operons are induced when the concentration of the specific Aliivibro fischeri autoinducer reached a relatively high concentration. This autoinducer is himself synthesized by the enzyme which is coded by the gene luxI.

Quorum sensing is very widespread, particularly in gram-negative bacteria.Pseudomonas aeruginosa, for example, uses "population sampling" processes to trigger a large number of unrelated when population density reaches a certain threshold gene expression.These genes subsequently allowing cells form a biofilm (which increases the pathogenicity of the body and prevents the penetration of antibiotics).

What is particularly striking quorum sensing is the specificity of the autoinducer that most common convention of the langue.Et can ask - naturally - what Darwinian process may have caused his arisal.Nous are only beginning to scale the foothills of the biology of development multicellulaire.Mais there is also evidence that cell signaling similar processes are at the higher influence on how cells work together taxa and cooperate on an interconnected unit.

This is a statement over telling information runs the show in biology?

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