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Medicine Science

Prions Evolve Despite Having No DNA 214

Posted by kdawson
from the wipe-that-foam-off-your-mouth dept.
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."
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Prions Evolve Despite Having No DNA

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  • genetic material (Score:3, Insightful)

    by Anonymous Coward on Sunday January 10, 2010 @04:46AM (#30713580)
    Genetic material and DNA aren't really synonymous, are they? Alien life that appeared independently of that on Earth would likely have "genetic material" that served a similar purpose to DNA, but wasn't DNA.

    Prions are proteins that, like viruses, replicate via a host cell. All the high-level principles of evolution by natural selection apply; it's just the low-level mechanisms that are quite different.
  • That's how (Score:2, Insightful)

    by eclectro (227083) on Sunday January 10, 2010 @04:47AM (#30713586)

    That must be how the Crystalline Entity [memory-alpha.org] came into being.

  • by Gopal.V (532678) on Sunday January 10, 2010 @04:49AM (#30713598) Homepage Journal

    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 :)

  • Not Surprised. (Score:5, Insightful)

    by nog_lorp (896553) on Sunday January 10, 2010 @04:51AM (#30713602)

    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? (Score:5, Insightful)

    by ZorbaTHut (126196) on Sunday January 10, 2010 @05:16AM (#30713650) Homepage

    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 (Score:5, Insightful)

    by glwtta (532858) on Sunday January 10, 2010 @05:33AM (#30713690) Homepage
    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:how long? (Score:3, Insightful)

    by SimonTheSoundMan (1012395) on Sunday January 10, 2010 @06:01AM (#30713750) Homepage

    No flames can kill prions.

  • Re:Surprising? (Score:4, Insightful)

    by sevennus (1702060) on Sunday January 10, 2010 @06:05AM (#30713776)
    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.
  • by mindbrane (1548037) on Sunday January 10, 2010 @06:12AM (#30713786) Journal
    it's late, i'm over tired and maybe i should have cooked that last brain i ate. anyway i did a reread of Darwin's TOOS and then binged on a buncha evolutionary theory and evo-devo stuff, this over the last 3 years. 1st off evolution theory, at least the mainstream stuff presupposes a genotype (dna) translated into a phenotype like me typing this. so the question should arise as to whether prions have a genotype source that has a transcription mechanism. old school Darwinianism as penned by Darwin drifted toward acquired characteristics a la Lamarck because Darwin didn't have any working knowledge of genetics even tho Mendel had sent him a draft of his work. somewhere over 95% of all species have gone extinct and after all the reading and questions i came away seeing life as a random walk of living crud crusting eons of dead crud. no winners no losers no game no gameplan just stuff that hasn't died yet on top of stuff that has; being slow cooked by a middle aged average sun.
  • Re:Not Surprised. (Score:3, Insightful)

    by digitig (1056110) on Sunday January 10, 2010 @06:54AM (#30713882)

    That's what cellular respiration is all about. It was an interesting discussion and, in the end, a lot of it depends on points of view. That of course is the problem. You don't think fire is alive because you know that fire isn't alive and if someone comes along and tells you that fire is now included in the scientific definition of things that are alive, you'll disagree, just like lots of people are still pretty upset that Pluto isn't a planet anymore. If you examine what is and isn't alive in enough detail, the boundary gets fuzzy enough that it becomes harder to know where to draw the line rather than easier.

    Yes, and that's where I think the summary gets it wrong. It talks about the definition of life, as if there's only one (probably the one that the author learned in grade school -- "respiration, reproduction etc.". As James Lovelock points out, "If we ask a group of scientists 'What is life?' they will answer from the restricted viewpoint of their own scientific disciplines. A physicist will say that life is a peculiar state of matter that reduces its internal entropy in a flux of free energy, and is characterised by an intricate capacity for self-organisation. ... A neo-Darwinist biologist will define a living organism as one able to reproduce and to correct the errors of reproduction by natural selection among its progeny To a biochemist, a living organism is one that takes in free energy as sunlight, or chemical potential energy, such as food and oxygen, and uses the energy to grow according to the instructions coded in its genes." (Quoted in Mary Midgley, Science and Poetry) Prions were probably already classified as life by the physicists, but the biologists hadn't bothered to ask them.

  • by Macka (9388) on Sunday January 10, 2010 @06:58AM (#30713886)

    Shame I don't have any mod points right now. That comic strip is quite funny and more on topic than off.

  • I'm skeptical (Score:3, Insightful)

    by BlueCoder (223005) on Sunday January 10, 2010 @07:19AM (#30713956)

    I'm not quite sure I would call it evolution. I can easily imagine that many prions replicate not only themselves but variations as well and those variations will produce variations of different proportions and so on and so forth. So just because you subjected a prion to an adverse environment for a particular copy of a prion only means that form will be less populous.

    It feels to me that this is less evolution and something more akin to chemical computation. Although ironically it does in some ways remind me of the poorly labeled Conway's game of life.

  • Matter. (Score:2, Insightful)

    by Tibia1 (1615959) on Sunday January 10, 2010 @07:44AM (#30714014)
    Any matter has one mission and one mission only: to find greater order. If matter without DNA or any prior form of order couldn't achieve more order, then life would not exist. Things want to be able to interact with their environment more efficiently, and must evolve to do so.
  • by giladpn (1657217) on Sunday January 10, 2010 @08:21AM (#30714128)
    As posts above testify, the word "evolution" is used more and more in contexts that have nothing to do with life.

    For example people talk a lot about the evolution of ideas, societies, and so on... Quite possibly, the philosopher Wilson is one of the popularizers of this approach.

    Anyway, this also leads to a different point - Evolution by itself is not a proof of the existence of Life. For example, Ideas or Societies are not living organisms, yet they do evolve.

    So the fact that prions evolve does not mean they are alive! One can fairly say that they are just a chemical (a protein) that can reproduce itself, evolve, and do damage.

    In Science, Mathematics and Philosophy, it is very common to take "edge cases" in order to better understand the limits of an idea. Prions give us a good example of something that can reproduce and evolve, yet its a chemical not a living organism.

    So what is "Life" ? Perhaps we should require the ability to perceive - awareness of ones surroundings - in order to define true life? In that case Bacteria aren't alive either, which is fine by me.

    Jellyfish and Lizards do qualify as alive. More generally, you would need some sort of functioning nervous system (however primitive) to be "alive". Brain-dead people would possibly not be "alive" by this definition.
  • by famebait (450028) on Sunday January 10, 2010 @08:25AM (#30714142)

    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.

  • Re:I'm skeptical (Score:2, Insightful)

    by Loomismeister (1589505) on Sunday January 10, 2010 @08:51AM (#30714238)
    What you have described is exactly what evolution is...
  • by mindbrane (1548037) on Sunday January 10, 2010 @09:02AM (#30714274) Journal
    Oddly i see it very much the opposite. It's because we know our state and can act to leave the world a better place for those who come after us, and, because we can act humanely and compassionately from choice that we can be more than our nature has endowed us to be. I like the idea of pissing in the abyss while wondering who's gonna win the playoffs, but that's just me.
  • Re:Rocks Too (Score:5, Insightful)

    by Hurricane78 (562437) <deleted@@@slashdot...org> on Sunday January 10, 2010 @09:18AM (#30714346)

    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.

  • Re:Not Surprised. (Score:3, Insightful)

    by phoenix321 (734987) * on Sunday January 10, 2010 @09:38AM (#30714410)

    We already have intelligent living fire.

    Did you consume hydrocarbons today? What about carbohydrates? (Stuff with hydrogen and carbon in it, at least)

    Did you inhale oxygen and exhale carbon dioxide? Did you somehow got rid of dihydrogenmonoxide or did the / a / one of the girl(s) block the bathroom the entire morning? :) - and did you emit heat while doing so?

  • by NotSoHeavyD3 (1400425) on Sunday January 10, 2010 @09:42AM (#30714432)
    that but not by much. Basically they'll say little changes like that (they call it micro-evolution) can happen but nope, no big ones into other species. (But anybody that's taken Bio 102 and seen how impossible it is to come up with a definitive answer to what is one species is and what is another knows that differential is horse-shit.) Guess they needed that so they could have an excuse why it was ok to take newer antibiotics and such. (You know, so they could allow the evolution that's so obvious you have to be pretty much insane to say it doesn't happen.)
  • by Qzukk (229616) on Sunday January 10, 2010 @10:06AM (#30714530) Journal

    It ate all of the Not-So Grand Canyons?

  • by CxDoo (918501) on Sunday January 10, 2010 @10:45AM (#30714730)

    You're right. However, whether prions evolve or not has no influence on their classification as (non-a)live matter.

  • by MightyMartian (840721) on Sunday January 10, 2010 @12:44PM (#30715452) Journal

    That's not the interesting part of this. First of all, prions were never consider life. They are not even nearly as complex as viruses, and no one really thought there was any kind of hereditary mechanism in what amounts to a relatively simple protein structure.

    What it does tell us is that where there is replication, there will be adaptive and evolutionary processes.

  • Re:Surprising? (Score:4, Insightful)

    by ZorbaTHut (126196) on Sunday January 10, 2010 @01:20PM (#30715730) Homepage

    No, this isn't what I mean. The vast majority of devices are built by understanding the concepts involved and designing a new machine off those concepts. If we, instead, just measured a machine that already existed, then built another one to those approximate specs, over and over again, you'd see designs that were slightly "better" flourishing while designs that were slightly "worse" dying out. Thus, evolution.

  • Re:Surprising? (Score:4, Insightful)

    by ZorbaTHut (126196) on Sunday January 10, 2010 @01:23PM (#30715750) Homepage

    But that's exactly my point. It doesn't matter how the formation occurs. If the "parent" can reproduce, in any way, from construction to repurposing to just hanging around the "child" until the child starts acting like the parent, then it counts as reproducing. It's not like I have memes sitting in my head getting pregnant - their "reproduction" is that I say something funny to someone, and he remembers it, and says it to someone else.

    Evolution is in no way restricted to lifeforms that can self-reproduce. Prions have a way to duplicate their important properties - their bizarre folding - and that's all that's necessary.

    (And yes, role models can be a form of reproduction.)

  • Re:Matter. (Score:3, Insightful)

    by goodmanj (234846) on Sunday January 10, 2010 @01:27PM (#30715772)

    This is what happens when you start taking anthropomorphism seriously. You get grand-sounding philosophical statements ("Matter has a mission", "nature abhors a vacuum", "information wants to be free" (woot flamebait!)) which have no basis in fact (see Magsol's spot-on reply in this thread).

  • by sco08y (615665) on Sunday January 10, 2010 @01:31PM (#30715808)

    We have a pretty, consistent tree of evolution extracted from fossyls. How difficult is it to look at the big picture and say that evolution s the most probable explanation?

    I've never looked at the fossil record. I think evolution happens because the math makes it work that way. But, yeah, from what I've heard the fossil record is pretty overwhelming.

    But Creationism is mostly an exercise in denying evidence. You can't very well carry the fossil record in your pocket, and if you're simply debating they have enough false claims that refuting the all means you can only draw even in the minds of the audience.

  • by HiThere (15173) <{ten.knilhtrae} {ta} {nsxihselrahc}> on Sunday January 10, 2010 @03:52PM (#30716848)

    I didn't understand how they could be surprised that prions evolve, so I checked with the original article. They weren't. They were interested in the rates of evolution and the persistence of strains that were selected against. Quite reasonable.

    Even totally inorganic matter evolves, in a rough sense. At it's basis evolution just asserts that those forms which are most suited to an environment tend to persist in that environment. This seems quite hard to challenge. Then it accepts Malthus computations on population, and asks: Given that it's obvious that not all descendants can survive, what does the two laws in combination imply?

    N.B.: Darwin didn't know ANYTHING about DNA. Genetics hadn't yet been recognized. (This was after Mendel, but long before he was discovered.) So the basis of evolution clearly CAN'T depend on those facts. Evolution is really quite simple, it's just the working out of the details that is complex. (Just as Boolean logic is quite simple, but it's a long and complex way from Boole to a compiled program written in C.)

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