[Cin]

Originally Posted by dreadgeek

Can you explain what you mean by "DNA specifically engineered to be antibiotic resistant" and "pumped into the food supply"? I ask for a couple of reasons:

1) Antibiotics do not, strictly speaking, affect 'naked' DNA. (Here I mean DNA that isn't in some living thing.) Antibiotics affect, well, bacterials but not viruses (RNA) and DNA is RNA with an extra strand, some sugar and one different base (T in DNA is U in RNA). So what doesn't effect RNA also doesn't effect DNA.

2) What do you mean by "pumped into the food supply" in the context of DNA? This seems to violate the central dogma of molecular biology. Put simply, DNA codes for proteins. So DNA that isn't coding for something in the context of being in the presence of a living thing isn't' doing anything. So how can DNA, absent a body in which to express itself, be *doing* anything? Are you saying that it is making antibiotic resistant proteins? That doesn't really make sense unless you are talking about it being inside a living thing.

3) Are you saying that someone cooked up DNA as a bacteriophage (a virus that infects bacteria)? If so, why on Earth would they have it code for resistance to antibiotics since the whole purpose of a bacteriophage would be to try to kill a bacteria not make it more resistant to antibiotics. What's more, there's a far less expensive way they could get the same effect. Simply have people take too many antibiotics, not use them correctly, use a lot of antibacterial soaps so that we're constantly turning the selective volume on bacteria up to eleven. Wait, that's what we're doing now.

I will admit that I do not read all of the literature but I do try to keep up with what is happening in molecular genetics particularly as it relates to our ongoing battle against pathogens. I'm not aware of the work you're talking about and really am not sure that I understand what you're saying. I don't want to derail the thread so if you want to write me privately or put it on its own thread, I really would like to understand what it is you're saying. Thanks.



Actually, the explanation that it's because of the overuse of antibacterials is actually the most simple and the most likely. Since bacteria are living things and since all living things are subject to variation, Darwinian selection operates on bacteria just as it does everything else. Since antibiotics literally kill bacteria and do so by making various chemical tricks happen, any variation that made a bacteria more resistant to that chemical attack would cause it to leave around more descendants than others. What has been going on since we first started using antibiotics is we have been selecting for antibacterial resistance in TB, staph, e. coli, and every other bacterial pathogen we care about. We've been using antibacterials since 1940 so just over 70 years. Given the very fast generation times of most bacteria (every 24 minutes for e. coli, under ideal conditions) and the fact that bacteria are gregarious with their genes and will just share and pick them up from any old bacterial colony we should expect resistance to naturally evolve in a population. It would be remarkable if it didn't happen.

So here I have to ask which is more likely? That bacteria are subject to Darwinian selection and that introducing antibiotics into the ecology of bacteria would inevitably (and rather quickly) lead to strains of bacteria that are resistant to antibiotics OR someone for no good reason introduced antibiotic resistance into the ecology of mammal infecting bacteria *knowing* that resistance was already evolving? (It's been known that it was happening all of my adult life, I first encountered this in 1991.)


Cheers
Aj

I don't want to derail the the thread either, but I do want to understand this as well. From what I can gather, and believe me gathering hurts my head, DNA used as markers in genetic engineering are somehow or other antibiotic resistant. I don't think it is a purposeful thing, it is a by product of using markers. At least that is what it sounded like to me. Then there is something about it being able to possibly do some kind of horizontal gene transfer thing, especially surrounding e-coli, which seems to be useful for genetic modification and we all have some so when we eat gmos that have this antibiotic resistant dna we might be developing it also. Or something like that anyway. Not sure how proven it is. Europe seems more disturbed by it than we are in the U.S. But even there some study decided it wasn't much of a threat to humans but two scientists disagreed and wanted an addendum added to the study. Or something like that. I can't find the study anymore. Read about it awhile ago. Anyway it doesn't sound like a great idea to me. And it seems like a more direct way to find oneself resistant to antibiotics. I think they have been doing this since 1970 or so. Does this make any sense?