Prions Evolve Despite Having No DNA

An anonymous reader writes "Scientists from the Scripps Research Institute have shown for the first time that 'lifeless' organic substances with no genetic material — prions similar to those believed responsible for Mad Cow disease and similar, rare conditions in humans — are capable of evolving just like higher forms of life. The discovery could reshape the definition of life and have revolutionary impacts on how certain diseases are treated."

Comments

Evolution is the good news ... wait, bad news?

[Gopal.V]

Natural selection doesn't pre-suppose DNA. Anything which multiplies to produce copies of itself, which can degrade/mutate between generations can evolve just in exactly the same way. Selection pressures work exactly the same. So does the chain reaction effect of multiplication of the survivors, resulting in major shifts in characteristics of a population.

But the actual story is the bad news part of it. That using anti-prion medication probably won't work all the time as it would just breed a drug-resistant breed of prions by preference.

Definitely bad news. We can forget about having the "saviour" take a bath in the daily oatmeal for our protection :)

Re:Evolution is the good news ... wait, bad news?

[famebait]

using anti-prion medication probably won't work all the time as it would just breed a drug-resistant breed of prions

Not necesarily. Unlike the changes available for lifeforms with their own DNA, there is probably a finite number of ways a given human protein can degrade into a replicating prion configuration. Most proteins probaly have no capacity for becoming prions. For others, the body is perfectly capable of dealing with them.

The capacity to become a prion is already built into the structure of the host protein in question, not aquired through exposure. So while this evolution is probably real and possibly a stumbling block for therapies, it remains confined to the space of potential configurations already inherent in our proteome, of which only a very small subset will cause trouble as prions.

Not Surprised.

[nog_lorp]

It's time we recognized that the interesting things about "life" are all just products of the fact that all kinds of systems can convey self-replicating entities of some sort, and they tend to be interesting and undergo evolutionary processes and etc. Whether they are non-biological DNA bundles, cellular organisms, oddly folded proteins, crystalized clay, etc.

So where are the nefarious / useful engineered prions at?

Re:Surprising?

[ZorbaTHut]

It's a little more complicated than that. There's basically three properties that are both necessary and sufficient for evolution to take place.

* Some sort of fitness function
* Reproduction, largely based on the properties of the "parent"
* Imperfect reproduction, so that variation can be introduced

Once you've got those three items, you have the potential for evolution.

That said, it should be pretty obvious that basically any frequently-duplicated structure in the physical world, whether it be made out of DNA, protein, or metal and gears, is going to have all three of those items - the third just thanks to the physical world being imperfect. Note that it's not required that it be capable of duplicating itself - if all machines were built by copying older machines, we'd get to see "machine evolution" as people tended to copy the ones that worked better and throw away the ones that didn't.

Of course it's also worth pointing out that none of these requires that the item exist in a physical sense - you can meaningfully talk about memetic evolution, societal evolution, language evolution, joke and humor evolution, so forth ad nauseum.

Re:Rocks Too

[glwtta]

Rocks evolve too.

Hasn't this bullshit "claim" been dredged up enough already? It's just a bit of really weak sensationalism from an attention-whoring geologist.

He himself doesn't even believe this nonsense, and does say, towards the end of that article that obviously "being changed by your environment" has nothing to do with "evolution", but hey, why not get some free publicity?

Re:Surprising?

[sevennus]

This is misleading, and upon second reading, it is some overly-philosophical hand-waving.

Yes, prions do not reproduce through the conventional genetic mechanisms. From my understanding, they encourage, through some direct protein-protein interaction, other polypeptides to fold incorrectly.

Think of it this way. HIV and other genetic disorders propagate through normal reproductive means. Like, if a person with an extraordinary innate musical ability has a child, that child will probably possess a natural ability for music.

However, if a talented musician adopts a child and then teaches him how to read music and how to play instruments, he will probably grow up to be equally talented.

Prions are similar to the latter case. They are encouraging other proteins, who don't in themselves possess any malicious function, the fold in such a way to attack the host.

This isn't reproduction. The "parent" prions are not in anyway responsible for the actual formation of the "child" prions. They are just responsible for causing them to become malicious, making them more role-model proteins than actual parents.

Re:Rocks Too

[Hurricane78]

But you’re no better. You insult the other side, and bring no arguments to the table. You’re obviously right... to us... but to them, you now just made it worse, making them protect themselves from your pointless attacks even more.

This time, I’ll do it for you:
The difference is, that Rocks have no fitness function. Which is the difference between undirected change and directed evolution.

But the next time, if you wanna act superior, bring an argument. Like a common basis, and proper logic on top of it.