Carl Zimmer writes about the discovery of powerful new antibiotics from frogs. The best thing about them is that they may be impervious to the development of resistance on the part of bacteria.

The best thing about them is that they may be impervious to the development of resistance on the part of bacteria.

I think there is more to this story. Could "evolution" itself be defeated?

Ah, there is more to the story:

The secret of frog skin promised a solution to this disaster. A drug based on antimicrobial peptides might be able to wipe out bacteria that had evolved resistance to other drugs. And even more exciting was the possibility that these new antibiotics might be resistance-proof. Bacteria might theoretically able to evolve resistance to antimicrobial peptides by changing the charge on their surface so that the molecules wouldn't be attracted. But that wouldn't be just a tweak to an enzyme or some other series of small changes: it would be a fundamental alteration of the beast. Experiments seemed to back up this hunch. Some scientists tried to produce resistant bacteria by randomly mutating their genes and then seeing whether any mutants could survive a dose of antimicrobial peptides. No luck.

But a Canadian evolutionary biologist named Graham Bell suspected that bacteria--and their evolutionary potential--might be more powerful than others thought. Michael Zasloff for one didn't think so. But as a good scientist, he was willing to put his hypothesis to the test. Remarkably, it failed.

The researchers began by exposing bacteria to low levels of antimicrobial peptides. They would then use a few of the survivors to start a new colony and then expose the bacteria to slightly higher levels of the poison. As they report in the Proceedings of the Royal Society of London, 30 out of 32 colonies evolved to be resistant to a full does of antimicrobial peptides. It took only about 600 generations for them to do the impossible.

The new paper doesn't offer any evidence for what the evolved bacteria are doing to escape antimicrobial peptides. It is hard to pinpoint mutations that produce new traits, and even harder to figure out exactly how they change the workings of a microbe. So we may have to wait to learn the trick that bacteria have discovered. But the results are enough to raise serious concerns about the future of antimicrobial peptides. People who take full doses of the drugs might wipe out all the bacteria infecting them, but microbes that are exposed to low levels--in people who don't take full prescriptions, in animals, or even in the environment--could evolve resistance. As the bacteria became stronger, they would be able withstand higher doses. They might gradually invade a new ecological niche: the world of full-strength antimicrobial peptides.

This reads to me that they did become resistant.

The take-home message? Our society needs to be able to think in Darwinian terms, something the Kansas Board of Education opposes.

This is cool to see!
I wrote an article about Zasloff's frog investigations for the long-defunct "Florida Oceanographic" magazine in the late '80's.

I think ALL theories should be presented to students and let the students make the decision as to which theory they want to believe in.

I think ALL theories should be presented to students and let the students make the decision as to which theory they want to believe in.

sorry about the double post.

Life as we know it probably came about because species developed resistance, or at least tolerance, to pressures. In that context, it is not inconceivable that frogs could develop a resistance to humans. We'd have to walk around watching for giant swooping tongues. Slurpppp!