Freethought & Rationalism Archive

Quetzal · 03-03-2003, 05:55 AM

It's even simpler than that. Of COURSE there's no new information in the genome. Of COURSE all codes were pre-existing. After all, we've never discovered a life form containing nucleic acids that weren't composed of A, C, T, or G (or U). No matter what the mutation, whether a point substitution or chromosome duplication or complete genome doubling, you'll never see anything but A, C, T, G (or U). Therefore, it is quite obvious that these were pre-existing, and no conceivable new codes can exist that weren't already there - at least in potential. So the first progenote that had any of the above DID contain the multipurpose genome for all of life. No new bases = no new information.

MortalWombat · 03-03-2003, 08:47 AM

Quote:

Originally posted by Nic Tamzek
Following the YEC link, however, indicates that they are making additional arguments, basically along the lines that resistance mutations are never information-increasing because while the mutant bacteria may be more fit in antibiotic environments, they are less fit in 'normal' (YEC quotes) environments.

In the case of streptomycin resistance (which is caused by a mutation in one of the ribosomal subunit genes), bacteria have actually acquired a second mutation that does make them just as fit in "normal" (ie, antibiotic-free) environments.

See this paper for for instance.

Here is the abstract:

Quote:

Proc R Soc Lond B Biol Sci 1997 Sep 22;264(1386):1287-91

Adaptation to the fitness costs of antibiotic resistance in Escherichia coli.

Schrag SJ, Perrot V, Levin BR.

Department of Biology, Emory University, Atlanta, GA 30322, USA.

Policies aimed at alleviating the growing problem of drug-resistant pathogens by restricting antimicrobial usage implicitly assume that resistance reduces the Darwinian fitness of pathogens in the absence of drugs. While fitness costs have been demonstrated for bacteria and viruses resistant to some chemotherapeutic agents, these costs are anticipated to decline during subsequent evolution. This has recently been observed in pathogens as diverse as HIV and Escherichia coli. Here we present evidence that these gentic adaptations to the costs of resistance can virtually preclude resistant lineages from reverting to sensitivity. We show that second site mutations which compensate for the substantial (14 and 18% per generation) fitness costs of streptomycin resistant (rpsL) mutations in E. coli create a genetic background in which streptomycin sensitive, rpsL+ alleles have a 4-30% per generation selective disadvantage relative to adapted, resistant strains. We also present evidence that similar compensatory mutations have been fixed in long-term streptomycin-resistant laboratory strains of E. coli and may account for the persistence of rpsL streptomycin resistance in populations maintained for more than 10,000 generations in the absence of the antibiotic. We discuss the public health implications of these and other experimental results that question whether the more prudent use of antimicrobial chemotherapy will lead to declines in the incidence of drug-resistant pathogenic microbes.

Nic Tamzek · 03-03-2003, 01:41 PM

Quote:

We show that second site mutations which compensate for the substantial (14 and 18% per generation) fitness costs of streptomycin resistant (rpsL) mutations in E. coli create a genetic background in which streptomycin sensitive, rpsL+ alleles have a 4-30% per generation selective disadvantage relative to adapted, resistant strains.

In other words, according to creationist information math:

1) Resistance mutation: lose information
2) Compensation mutation: lose information because now "normals" are at a disadvantage
3) Back-mutation to non-resistant "normal" resistance state: lose information

So, all the quote shows is that the bacteria lost information in three steps, even though it ended up with an unharmful resistant phenotype!

Doubting Didymus · 03-03-2003, 02:09 PM

Just revising one of my previous statements:

BH asked:
Did the resistant bacteria get the ability to be resistant from other bacteria already possessing the ability?

I, in my temporary ignorance, answered:
Not by any mechanism I'm aware of.

... Which I now know to be completely false. In fact, the very night after I made that post I had a microbial ecology lecture in which I learned that bacteria very often exchange genetic material through those little hairs you often see on pictures of bacteria. Usually used to attach to things, some pili are also used to transfer genetic material to other bacteria. Antibiotic resistance can and does get transferred from one bacteria to another in this way.

See? Those hairy things.

Dr Rick · 03-03-2003, 02:59 PM

Quote:

Originally posted by Doubting Didymus
See? Those hairy things.

Yeah, well god obviously put them there right after the Fall.

Rick

B. H. Manners · 03-03-2003, 06:50 PM

Let me ask one more question.

Can you take a little bitty bacteria and see if it has the gene that makes it resistant to a said antibiotic without killing it, then if it doesn't, put it in the petri dish and add antibiotic after the culture grows a very large population?

B. H. Manners · 03-03-2003, 07:13 PM

Quote:

Originally posted by Nic Tamzek
This would be easy to test by subjecting the original population (from the first petri dish) to an antibiotic and seeing if they were predominantly resistant or not. If the overwhelming number are not resistant then you have very high odds that the samples that you took from this population (to start the clonal cultures in new petri dishes) before you nailed it with the drug shared this nonresistance.

The point is that no matter what you start with, you can via sampling end up with many cultures, each of which is descended from a single bacterium. This single bacterium will, the vast majority of the time, have the traits of the parent population. Therefore any differences that develop in the descendents of the single bacterium are novel traits.

Creationists usually don't go for divine intervention in the lab anyhow...

nic

The problem is that Creationists will argue that the parent bacteria had the gene, and it was somehow lost to the majority of the critters in the petri dish. The only way to counter their objection is to prove that the parent did not have the gene in the first place.

Doubting Didymus · 03-03-2003, 07:42 PM

Quote:

Originally posted by B. H. Manners
The problem is that Creationists will argue that the parent bacteria had the gene, and it was somehow lost to the majority of the critters in the petri dish. The only way to counter their objection is to prove that the parent did not have the gene in the first place.

But we KNOW that the parent didn't have the gene, because it comes from a population in a petri dish that was later shown to have no resistance to the antibacterial. For the parent to have the protective gene, it would have to have been the only individual in that entire dish that had the gene. If the experiment is repeated a few times, the probability against the gene being in the original founder to begin with just keeps compounding. Remember that what has actually been done is to take a single bacterium from a petri dish, and then kill all the bacteria in that dish before founding a new colony, ensuring that nothing from that original dish was resistant. So the probability is overwhelming that the bacteria you took to found the new colonies didn't have the protection.

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03-03-2003, 05:55 AM	#11
Quetzal Senior Member Join Date: Nov 2001 Location: Ecuador Posts: 738	It's even simpler than that. Of COURSE there's no new information in the genome. Of COURSE all codes were pre-existing. After all, we've never discovered a life form containing nucleic acids that weren't composed of A, C, T, or G (or U). No matter what the mutation, whether a point substitution or chromosome duplication or complete genome doubling, you'll never see anything but A, C, T, G (or U). Therefore, it is quite obvious that these were pre-existing, and no conceivable new codes can exist that weren't already there - at least in potential. So the first progenote that had any of the above DID contain the multipurpose genome for all of life. No new bases = no new information.

03-03-2003, 02:09 PM	#14
Doubting Didymus Veteran Member Join Date: Jul 2002 Location: East Coast. Australia. Posts: 5,455	Just revising one of my previous statements: BH asked: Did the resistant bacteria get the ability to be resistant from other bacteria already possessing the ability? I, in my temporary ignorance, answered: Not by any mechanism I'm aware of. ... Which I now know to be completely false. In fact, the very night after I made that post I had a microbial ecology lecture in which I learned that bacteria very often exchange genetic material through those little hairs you often see on pictures of bacteria. Usually used to attach to things, some pili are also used to transfer genetic material to other bacteria. Antibiotic resistance can and does get transferred from one bacteria to another in this way. See? Those hairy things.

03-03-2003, 06:50 PM	#16
B. H. Manners Veteran Member Join Date: Jan 2002 Location: Texas Posts: 1,213	Let me ask one more question. Can you take a little bitty bacteria and see if it has the gene that makes it resistant to a said antibiotic without killing it, then if it doesn't, put it in the petri dish and add antibiotic after the culture grows a very large population?

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