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Author Topic:   Disabling Bacterial Resistance
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Message 4 of 60 (216596)
06-13-2005 10:26 AM
Reply to: Message 1 by gnojek
05-24-2005 3:55 PM

I'm wondering if this SOS response is a response to antibiotic treatment or to DNA damage. I suspect the latter.

If a bacterium has sustained a large amount of DNA damage (from whatever source), it would be helpful to activate a set of DNA polymerases that aren't so picky about error checking. A last resort if you will. A lot of these bacteria will probably die due to serious damage to important genes, but a few may get though, with an extremely high mutation rate. So the development of antibiotic resistance may just be a side effect of a simple survival mechanism rather than the whole purpose behind it.

A good test would be to see if this mechanism is activated by antibiotics that don't result in DNA damage.

However it isn't unusual that bacteria have evolved various defences against antibiotics. After all, microorganisms have been fighting amongst themselves for billions of years, and antibiotics are just some of the weapons they have been using. For example, a bacterium I worked on many years ago (Klebsiella planticola) naturally carried a beta-lactamase enzyme, which sole purpose is to defend against penicillin. Presumably it was exposed to penicillin in the wild, not from human intervention.


This message is a reply to:
 Message 1 by gnojek, posted 05-24-2005 3:55 PM gnojek has replied

Replies to this message:
 Message 13 by Trixie, posted 06-13-2005 3:53 PM bugeater has replied
 Message 26 by gnojek, posted 06-14-2005 5:35 PM bugeater has replied

Inactive Member

Message 17 of 60 (216725)
06-13-2005 10:24 PM
Reply to: Message 13 by Trixie
06-13-2005 3:53 PM

Re: The SOS response
Thanks for that Trixie. It is as I expected. So in reality it is the antibiotic that is causing the damage, not the SOS response. Not surprising that an agent that leads to DNA damage would up the mutation rate :rolleyes:

So it is hardly a case of ID. After all, DNA damage response mechanisms are pretty important for all life and evolved very early. In mulitcellular organisms the seriously DNA damaged cell is likely to undergo programmed cell death (or you risk things like cancer), but in a single celled organism it is probably advantageous to turn off the error checking and have a go.

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Inactive Member

Message 33 of 60 (216995)
06-14-2005 11:53 PM
Reply to: Message 31 by mike the wiz
06-14-2005 9:19 PM

Re: Goodbye, mike
You have chosen wilfull ignorance of the answers the bible gives, which are better than the natural ones.

If I choose to find answers with God and you choose to without, then why do you you hold this against me?

You said belief isn't a choice. I can't choose to believe evolution, I just can't make myself think that the magnificent creation came about all by itself etc.. I tried, and I was fooling myself.

As someone who has worked and studied in many fields that touch molecular biology, including cancer biology, Virology, Bacterology etc. etc. I'm afraid that natural selection and evolution has explained everything I've seen. For example, one of the projects I am working on began because a virus mutated in such a way that it evaded the surveillance method that was in place - survival of the fittest. I see no evidence that God did it. The bible gives no answers at all. Logically it isn't even an option.

Evolution at its core is such a simple idea, which makes it so powerful. The concept of an all mighty being being responsible is not simple and there is absolutely no evidence for it.

The concept of evolution isn't a belief system in the way a religion is. There is no faith involved. It is just a model that fits the data exceptionally well.


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 Message 31 by mike the wiz, posted 06-14-2005 9:19 PM mike the wiz has not replied

Inactive Member

Message 50 of 60 (217285)
06-15-2005 10:55 PM
Reply to: Message 26 by gnojek
06-14-2005 5:35 PM

A mold produces an antibiotic compound to battle off bacteria that may eat it or its food source.

But a species of bacteria developed a weapon against that.

It's like a bio-arms race.

It certainly is interesting. :) The trouble we are having with antibiotic resistant bacteria is likely due to this constant battling taking place in the microscopic world. Most (all?) antibiotics come from microorganisms. So for any one antibiotic, there is already the counter to it in existance in other microorganisms. The human pathogen we are treating with the antibiotic just needs to get the required counter and they are resistant. And bacteria can be quite promiscuous when it comes to DNA. :rolleyes:

Even restiction enzymes which are of vital importance in recombinant DNA technology (they are the "scissors") arose as a defence in bacteria against bacteriophage (virus) infection.

Thinking about this makes me wonder if it is a case against "intelligent design". Why would a creator give a microorganism a weapon and then render that weapon useless by giving its foe the counter weapon? :confused: In a way these weapon/counter-weapon pairs could just be considered the leftovers of an arms race. But if they were created and didn't evolve, then no such arms race would ever have taken place.


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