Editing Quorum sensing (section)

{{Short description|Biological ability to detect and respond to cell population density}}

{{More citations needed|date=April 2024}}
In [[biology]], '''quorum sensing''' or '''quorum signaling''' ('''QS''')<ref name="Lupp-et-al-2003" /> is the process of cell-to-cell communication<ref>{{cite journal | pmc=3543102 | date=2012 | last1=Rutherford | first1=S. T. | last2=Bassler | first2=B. L. | title=Bacterial Quorum Sensing: Its Role in Virulence and Possibilities for Its Control | journal=Cold Spring Harbor Perspectives in Medicine | volume=2 | issue=11 | pages=a012427 | doi=10.1101/cshperspect.a012427 | pmid=23125205 }}</ref> that allows bacteria to detect and respond to cell [[population density]] by [[gene regulation]], typically as a means of acclimating to environmental disadvantages.<ref name=":7" />

Quorum sensing is a type of [[Cell signaling|cellular signaling]], and can be more specifically considered a type of [[paracrine signaling]]. However, it also contains traits of [[autocrine signaling]]: a cell produces both an [[autoinducer]] molecule and the receptor for the autoinducer.<ref name=":7">{{Cite journal |last1=Postat |first1=J |last2=Bousso |first2=P |date=September 11, 2019 |title=Quorum Sensing by Monocyte-Derived Populations |journal=Frontiers in Immunology |volume=10 |issue=2140 |page=2140 |doi=10.3389/fimmu.2019.02140 |pmid=31572366 |pmc=6749007 |doi-access=free}}</ref> As one example, quorum sensing enables [[bacteria]] to restrict the expression of specific [[gene]]s to the high cell densities at which the resulting [[phenotype]]s will be most beneficial, especially for phenotypes that would be ineffective at low cell densities and therefore too energetically costly to express.<ref>{{Cite journal|last1=Papenfort |first1=K |last2=Bassler |first2=B |date=February 11, 2017 |title=Quorum-Sensing Signal-Response Systems in Gram-Negative Bacteria |journal=Nature Reviews Microbiology |volume=14 |issue=9 |pages=576–588 |doi=10.1038/nrmicro.2016.89 |pmid=27510864 |pmc=5056591 }}</ref>

Many species of bacteria use quorum sensing to coordinate [[gene expression]] according to the density of their local population. In a similar fashion, some [[social insects]] use quorum sensing to determine where to nest. Quorum sensing in pathogenic bacteria activates host immune signaling and prolongs host survival, by limiting the bacterial intake of nutrients, such as [[tryptophan]], which further is converted to [[serotonin]].<ref name=":4">{{cite journal|vauthors=Jugder BE, Batista JH, Gibson JA, Cunningham PM, Asara JM, Watnick PI |title=Vibrio cholerae high cell density quorum sensing activates the host intestinal innate immune response |journal=Cell Reports |volume=40 |issue=12 |pages=111368 |date=September 2022 |pmid=36130487 |doi=10.1016/j.celrep.2022.111368 |pmc=9534793}}</ref> As such, quorum sensing allows a [[Commensalism|commensal]] interaction between host and pathogenic bacteria.<ref name=":4" /> Quorum sensing may also be useful for cancer cell communications.<ref>{{cite journal |vauthors=Ali I, Alfarouk KO, Reshkin SJ, Ibrahim ME |title=Doxycycline as Potential Anti-cancer Agent |journal=Anti-Cancer Agents in Medicinal Chemistry |volume=17 |issue=12 |pages=1617–1623 |date=16 January 2018 |pmid=28270076 |doi=10.2174/1871520617666170213111951}}</ref>

In addition to its function in biological systems, quorum sensing has several useful applications for computing and robotics. In general, quorum sensing can function as a decision-making process in any [[decentralized system]] in which the components have: (a) a means of assessing the number of other components they interact with and (b) a standard response once a threshold of the number of components is detected.
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