Talk:Quorum sensing/Archive 1

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yeah more links?

I may be totally off-base, but I have a distinct memory of reading somewhere that some slime molds are capable of "fooling" the quorum sensing of some bacteria, and thus "herding" them. I may have misinterpreted something... -- Jussi-Ville Heiskanen 02:49, Dec 15, 2003 (UTC)

Wow, interesting stuff and rather well written; I'd like to see some 'See Also' links for this page, but I'm not too sure what would be apt. --ImABadBroth 01:46, 24 March 2007 (UTC)

complicated

I guess the subject is complicated, but could somebody clear up some of the long winded sentences. It could make things easier... a little bit anyway. — Preceding unsigned comment added by Drnsacharya (talk • contribs) 11:35, 6 June 2007 (UTC)

Cell density is not population density

A lot of people, when speaking/writing about quorum sensing, tend to mention cell density or bacterial density a lot, without realizing that it's semantically a huge nonsense. In fact, they would like to talk about population density, and this should systematically be pointed out to them.

Density of matter, either be living or inert, is defined as a ratio of units of mass per units of volume. One can increase the density of any matter for example by applying pressure and decreasing its volume. If a bacterium was so shrunk by pressure to the half of its original volume, its density would then double. Therefore, people that say that bacteria adjust their gene expression according to their density are actually implying that by compressing enough of the cells one could force them to express certain genes (that is certainly true) and that those genes that would be expressed under such conditions would define the quorum sensing regulome (that is absolutely false!).

Therefore, whoever pretends to be talking sensibly about quorum sensing and understands the fundamental notions of its principles should rather talk about the correlation between gene expression and population density, expressend in number of cells per unit of volume, and not in a nonsense cell or bacterial density, which is a real but completely unrelated physical parameter expressed in kilograms per m3.

Sophos II (talk) 23:29, 6 December 2007 (UTC)

On "Modelling"

This section is rather tangential/off-topic. Does this article really need 5 paragraphs of fiddling with an equation? I'm not sure it demonstrates anything useful about quorum sensing. In any case, I think one might make a strong case that this is original research. I'd fix it myself, but I personally find little or no redeeming value in it. Would anyone care to fix it, or consent to its deletion? --♦♦♦Vlmastra♦♦♦ (talk) 01:20, 31 December 2007 (UTC)

Absolutely agree. I agree that it can be trimmed down to one sentence or deleted. Antorjal (talk) 14:20, 31 December 2007 (UTC)
I went ahead and deleted it, since I didn't find much I thought was important. I have also noticed that the user responsible for this content, 66.215.123.233 (talk), has been editing mostly to include Kleiber's Law in tangential areas such as Junk DNA. --♦♦♦Vlmastra♦♦♦ (talk) 21:32, 2 January 2008 (UTC)

Added a few cross-links

I added a few cross links, to AHL's and AI-2/autoinducer-2. I created the page aboute AI-2 today and it is in desperate need of more info, I have a bit about it, a few references, and a structure and IUPAC name that is it. I hope that I did it properly (I may have done too many) and that no one minds.PedroDaGr8 (talk) 17:37, 31 October 2008 (UTC)

Quorum sensing may or may not require the use of receptors

In an early paragraph, the phrase "These bacteria also have a receptor that can specifically detect the signaling molecule..." however, receptors for some quorum sensing molecules (I'm thinking surfacin in B. subtilis) have never been discovered and it would be premature to assert that all autoinducers' effects are through receptor-mediated signaling. In point of fact, a recent paper in PNAS has recently presented evidence suggesting that surfactin's quorum sensing effect in biofilm production is not through sensing surfactin, but instead on surfactin's action on the cell's membrane. The authors suggest that surfactin creates pores with high potassium selectivity, and it is either a) the sensing of intercellular K+ or b) the actual leakage of K+ across the membrane that triggers biofilm formation. Other molecules that cause K+ leakage also restored biofilm formation in non-surfactin synthesizing mutantns. I mention this because it's generally well accepted that surfactin is a quorum sensing molecule for B. subtilis yet no receptor manages to turn up, and this recent paper concludes that it's method of action is not receptor-mediated. Lopez D, Fischbach MA, Chu F, Losick R, Kolter R (2009) Structurally diverse natural products that cause potassium leakage trigger multicellularity in Bacillus subtilis. PNAS 106(1): 280-285

67.174.180.186 (talk) 07:35, 29 January 2009 (UTC)

I don't think quorum sensing is a type of descision making

The definition of quorum sensing is a difficult problem partly because the context in which the term is applied keeps changing (growing) and partly because it is difficult for us to grasp and communicate how this kind of complex behavior can occur without recourse to metaphors that attribute a degree of non-existent intentionality to the system under observation. The initial attempt in this article was pretty good, if limited: 

“Quorum sensing is the ability of bacteria to communicate and coordinate via signaling molecules.”

That was simple, accessible and accurate at the time (before the term was applied to social insects-more about that in a minute). Several minor attempts were made to improve on it but they were rapidly discarded. This is what eventually replaced it:

“Quorum sensing is the process by which bacteria coordinate their gene expression according to the local density of bacteria producing signaling molecules.”

This was better because it specified that it is gene expression that is coordinated and it attempts to bring in the idea of population density, though not well. It also suffers in accessibility (compare ‘process by which’ and ‘ability’) and can be read to imply intentionality to bacteria, though I doubt the author intended that.

Both of these were supplanted by the current definition by Michelanious, who wanted, rightly, to point out that the term no longer applies only to bacteria. Instead of improving the definition by narrowing it, s/he tried to make it more accurate by extending it, thus:

“Quorum sensing is a type of decision-making process used by decentralized groups to coordinate behavior...”

Such a broad definition can include social insects and computer programs (and perhaps even some human decision making processes), but it exacerbates the problem of anthropomorphizing. It runs afoul of a point-of-view problem. It is only from a certain point of view that bacteria can be said to ‘decide’ to express genes. And that is not my point of view and I doubt it is the point of view of most of the intended audience.

Quorum sensing is... an ability... a process... a type of decision-making... I used to think ‘quorum sensing’ was 1) a stimulus 2) a response 3) the qualification that the stimulus is (constantly) produced by the individual showing the response but in quantities so small it ordinarily diffuses away before reaching the threshold concentration 4) The qualification that increased concentrations (frequency) of the stimulus produces increased production of the stimulus 5) the high correlation in natural environments of increased concentration of stimulus with increased population density. That about covered it.

But the metaphors of communication with all the attendant implied intentionality, and now decision-making, are so appealing and easy.

It seems to me the distinction between the constant production of AHL by vibrio fischeri and the occasional dance of a nest seeking bee is significant, but already lost. So, is the problem of recognizing the similarities between certain bacteria, certain social insects and certain computer programs solved at the expense of loosing the distinctions?

It seems to me all that is left is that quorum sensing is a system of stimulus and response correlated to population density. I propose that as the opening statement. But out of respect for Michelanious who put so much work into this article, I don’t want to make a change without discussing it first.

Baon (talk) 00:25, 25 January 2009 (UTC)

Agreed - I am of the opionion that quorum sensing is not 'decision-making' because there is no cognitive function going on, the appearance of 'co-operation' is a result of the combined activity of all the individuals, there is no instict for co-operative behaviour at the level of the organism. Master gopher (talk) 04:48, 5 June 2009 (UTC)

am i missing something

1. I mean I love the royal society and their philosophical transactions, but is that link just bunk or what. it's more like their ad page; did i miss the links? i mean i know how to get access free through my university, but I hate these dumb pages that just link to more ads. did i miss the pdf link? next thing I knew I was back in 2008, and where's the special issue. this ain't the place to advertise overpriced academic journals, right? Potamites (talk) 05:18, 5 March 2008 (UTC)

oh click on this "To access and purchase articles online, click here. The introduction to the issue is FREELY AVAILABLE." can't it just link to there: http://journals.royalsociety.org/content/w26732234707/?p=c1685368363e450faabedd3ee8fd60dc&pi=3

2. I really just need the name of that prof that discovered this stuff like not even that long ago and after no non-wiki site bounced back the reference for me, since apparently I think that she needs the credit more than anyone else does, I figured, surely wiki won't let me down, but I was wrong. maybe she doesn't deserve the credit; but it makes me feel smart to care.Potamites (talk) 05:18, 5 March 2008 (UTC)

If you are talking about Bonnie Bassler, she did not discover Quorum sensing. She has had an important role but she certainly did not discover it and has not contributed a proportion of work to the field that would merit special attention to her here. She has done a wonderful job of bringing the field into the public eye. The work on the Bobtailed squid was preformed in the 1960s by Kempner and Hanson (1968) and bought together by Nealson KH and Hastings JW in 1979. The term Quorum sensing was first used by Fuqua in 1994. — Preceding unsigned comment added by 128.243.253.104 (talk) 14:01, 9 January 2012 (UTC)

I added this title so as not to pretend I was saying what he said:

Section 1: Quorum Sensing

Two issues here:

This section uses (undefined) expert terms that will be confusing to the average reader.

  • What is a "signaling molecule?"
  • What is a "KG medium?"
  • What are "quorum quenching bacteria?" They appear to be related to the topic, but the term has not been explained or defined.
  • What is an "unculturable" environment? I thought one cultured bacteria, not environments. It's not clear if this a valid, field-specific term or a grammatical error. (For what it's worth, my spell checker doesn't recognize the term).
  • What is an "isolated quorum quenching bacterium?"
  • What is an "AHL degradation kinetic?" (Seriously people?)
  • What is "rapid resolution liquid chromatography (RRLC)?" What is the relevance, in the context of Quorum Sensing, of using it to study an "AHL degradation kinetic?" (This sentence is incomprehensible to the non-expert).

The section characterizes the topic entirely in terms of biology.

  • The introduction implies that this topic has broader applications in other domains such as systems analysis, computing, and robotics. If that is indeed the case, the concept should be defined and explained here in more general terms that are easier for the uninitiated to comprehend.

paudav (talk) 04:37, 6 October 2012 (UTC)

Overemphasizes Biology

The content in the biology section somehow seems too specific for this article.

  • It appears there are other articles that cover the same topics under different titles on Wikipedia, such as "Cell Signaling," "Autocrine signalling," or "Paracrine signalling." These might be more appropriate places for this level of detail. If the article actually deserves to carry this much detail about the biology of Quorum Sensing, it seems like it should feature information about what makes it different from "Cell Signaling." If it doesn't, it seems to me that large amounts of this biology content should probably be merged into/with "Cell Signaling." If that has the net effect of making the article just a few paragraphs long, I don't think that would be a tragedy.

paudav (talk) 04:37, 6 October 2012 (UTC)

Plagarism or properly cited?

This edit made a wholesale copy of section from a biotech company's website. It has a reference, but I don't think that's sufficient. Help?

http://en.wikipedia.org/w/index.php?title=Quorum_sensing&action=historysubmit&diff=354961441&oldid=354780510

http://quorumex.com/content/anti-quorum-sensing-qs-technology

Markluffel (talk) 19:04, 23 November 2010 (UTC)

The source was cited so it is not so much plagiarism as likely Copyright infringement, so I have removed it on the latter grounds. Thank you for bringing this up. -84user (talk) 15:48, 14 December 2012 (UTC)

Quorum sensing applies to more than bacteria!

I am adding some info on social insects and other systems that use quorum sensing. I also edited the current content to make it more organized. —Preceding unsigned comment added by Michelanious (talk • contribs) 09:55, 7 May 2008 (UTC) It's always neat to find parallels between disciplines!

--Although Quorum sensing is at many levels, the nlm.nih.gov MeSH term defines it on microbiologic level: "A phenomenon where microorganisms communicate and coordinate their behavior by the accumulation of signaling molecules. A reaction occurs when a substance accumulates to a sufficient concentration. This is most commonly seen in bacteria".[1] Maybe there is a better, wider authoritative definition in biology database which can be referenced? Yohananw (talk) 00:22, 14 April 2013 (UTC)

Etymology

Is there any papers that actually explains where did quorum sensing got its name? It might be really helpful to add such sections to this article. -Mys_721tx (talk) 03:27, 18 February 2014 (UTC)

Mechanism incomprehensible

The final para of the section 'Mechanism' is incomprehensible. I have tried to parse it a few times and feel that it should be rewritten. I will not offer any editing proposals as the subject is out of my scope of competence (though the poorly expressed text itself is not!). Sisjon912 (talk) 19:00, 23 January 2017 (UTC)

I removed the incomprehensible paragraph because it was copied verbatim from the cited source. CatPath (talk) 20:11, 23 January 2017 (UTC)

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