Freethought & Rationalism Archive

Oolon Colluphid · 04-29-2002, 05:27 AM

From today's Guardian:

<a href="http://www.guardian.co.uk/medicine/story/0,11381,706793,00.html" target="_blank">Bacteria 'send messages' to ailing colonies</a>

Quote:

British scientists have caught bacteria in the act of passing information to each other - even when separated by a plastic wall. The discovery could throw new light on the spread of antibiotic resistance in hospitals.

Mathematical physicist Alan Parsons and biologist Richard Heal, work for QinetiQ - formerly the Ministry of Defence science laboratory - at Winfrith in Dorset. They report in the Journal of Applied Microbiology that they grew separated colonies of bacteria, one in an ordinary nutrient, one in a dish of food that had been spiked with antibiotic.

At first, the medicinally-treated bacteria began to die. If they were totally sealed off from the healthy bacteria next door, they would all die. But if there was a small gap through which air could pass between the two colonies, the ailing bacteria would recover.

The only conclusion could be that the healthy, stable bacteria next door were sending their stricken cousins some kind of survival advice - in the form of information about antibiotic resistance.

I�ve looked through the online tables of contents of the Journal of Applied Microbiology, but can�t find this. Anyone know any more? Sounds fascinating -- I wonder how creation explains it.

TTFN, Oolon

Late_Cretaceous · 04-29-2002, 07:33 AM

It may not be all that far fetched, bacteria continue to have a lot of surprises for us. I have found in debating creationists that bacteria are often assumed to be simple, asexual and primitive. However, nothing could be further from the truth. I think of them as being highly specialized, extrememly sucessful - miniaturized organisms. Bacteria have been playing the game of life for an very long time, and some may cling to life in some places even after the sun has expired. They form colonies (biofilms) with specialized member, can withstand prolonged periods of dormancy, pick up stray bits of DNA and incorporate them, encode proteins bi-directionally along their DNA, the list goes on and on.

pseudobug · 04-29-2002, 08:18 AM

Oolon,

Bacteria have a means of cell-to-cell communication called "quorum sensing". This phenomenon was first discovered in conjunction with Vibrio fischeri bioluminescence. These little bugs live in the ocean and, just so happen to fluoresce when suffucient numbers of cells colonize certain marine organisms.

In Vibrio, when a colony of bacteria reach a certain density or "quorum", they produce and excrete something called an autoinducer (in vibrio, it is a homoserine lactone). This autoinducer goes can be taken up by adjacent cells and binds with a specific sensing protein for the autoinducer called a "response regulator" that transcriptionally activates the structural genes for bioluminescence in Vibrio spp.

This is a burgeoning area of microbial research as quorum sensing has been found to play a role in many different process such as formation of biofilms (bacteria are bad about clogging things up), antibiotic resistance (quorum sensing apperas to upregulate certain efflux pumps), turn on virulence factors of different sorts in human pathogens, disease processes in plants, etc.

You can find a relatively short blurb outlining quorum-sensing mediated regulatory cascades at <a href="http://info.bio.cmu.edu/Courses/03441/TermPapers/99TermPapers/Quorum/mechanisms.htm" target="_blank">this link</a>

As I said above, homoserine lactones are the best studied of the quorum sensors, although some of the grame +'ive species have peptide autoinducers. At any rate, just do a google search on "quorum sensing" and you can find an awful lot of links about the matter.

The article you linked is very intriguing. It would imply that certain small molecules can become airborne and reach high enough concentrations that they can effect gene expression in nearby cells not connected by a more easily diffusible milleau such as a liquid or semi-solid. On the surface, it seems rather implausible that a sufficient concentration of small molecules could accumulate in a hospital environment to aid in resistance; but hey, just a little over 200 years ago, "evil spirits" were the cause of contagious diseases.

[ April 29, 2002: Message edited by: pseudobug ]</p>

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04-29-2002, 07:33 AM	#2
Late_Cretaceous Veteran Member Join Date: Oct 2001 Location: Alberta Posts: 1,049	It may not be all that far fetched, bacteria continue to have a lot of surprises for us. I have found in debating creationists that bacteria are often assumed to be simple, asexual and primitive. However, nothing could be further from the truth. I think of them as being highly specialized, extrememly sucessful - miniaturized organisms. Bacteria have been playing the game of life for an very long time, and some may cling to life in some places even after the sun has expired. They form colonies (biofilms) with specialized member, can withstand prolonged periods of dormancy, pick up stray bits of DNA and incorporate them, encode proteins bi-directionally along their DNA, the list goes on and on.

04-29-2002, 08:18 AM	#3
pseudobug Regular Member Join Date: Jan 2002 Location: land of confusion Posts: 178	Oolon, Bacteria have a means of cell-to-cell communication called "quorum sensing". This phenomenon was first discovered in conjunction with Vibrio fischeri bioluminescence. These little bugs live in the ocean and, just so happen to fluoresce when suffucient numbers of cells colonize certain marine organisms. In Vibrio, when a colony of bacteria reach a certain density or "quorum", they produce and excrete something called an autoinducer (in vibrio, it is a homoserine lactone). This autoinducer goes can be taken up by adjacent cells and binds with a specific sensing protein for the autoinducer called a "response regulator" that transcriptionally activates the structural genes for bioluminescence in Vibrio spp. This is a burgeoning area of microbial research as quorum sensing has been found to play a role in many different process such as formation of biofilms (bacteria are bad about clogging things up), antibiotic resistance (quorum sensing apperas to upregulate certain efflux pumps), turn on virulence factors of different sorts in human pathogens, disease processes in plants, etc. You can find a relatively short blurb outlining quorum-sensing mediated regulatory cascades at <a href="http://info.bio.cmu.edu/Courses/03441/TermPapers/99TermPapers/Quorum/mechanisms.htm" target="_blank">this link</a> As I said above, homoserine lactones are the best studied of the quorum sensors, although some of the grame +'ive species have peptide autoinducers. At any rate, just do a google search on "quorum sensing" and you can find an awful lot of links about the matter. The article you linked is very intriguing. It would imply that certain small molecules can become airborne and reach high enough concentrations that they can effect gene expression in nearby cells not connected by a more easily diffusible milleau such as a liquid or semi-solid. On the surface, it seems rather implausible that a sufficient concentration of small molecules could accumulate in a hospital environment to aid in resistance; but hey, just a little over 200 years ago, "evil spirits" were the cause of contagious diseases. [ April 29, 2002: Message edited by: pseudobug ]</p>

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