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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."
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.
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That must be how the Crystalline Entity came into being.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
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 :)
Quidquid latine dictum sit, altum videtur
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?
im in ur prions
redesigning them
-- God
Even from a purely materialist perspective, it seems reasonable to ponder a class of materials that replicate themselves. How exactly they do so might be more or less complex but the basic idea that it's possible to configure matter in a way that it replicates itself doesn't seem that absurd. And there's no particular reason it has to be DNA --- there are even purely mechanical possibilities.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
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.
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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?
sic transit gloria mundi
Not really related, but it is entirely possible for humans to be "alive" in a physical sense even after they are brain dead. As long as they are hooked up to respirators etc., they can be kept alive indefinitely. To date, no human being is ever known to have regained consciousness after brain death.
The _big_ catch here is that most physicians are not properly trained to test for brain death. Most physicians will just see a flat line on an EKG and declare the patient brain dead. I used to work at an organ transplant center, where there were technicians that went through a formal checklist to make sure the patient really is brain dead. It was not uncommon to find patients who did not meet the strict criteria. In the most dramatic example, a 3-yo boy was supposedly brain dead, and he was in the operating room, ready to have his organs removed. The technicians discovered that his pupils did respond to light, so they rushed him out of the OR. On the way back to his room, the boy opened his eyes and smiled. But then he went back into a coma and died 5 days later.
Needless to say, the boy's parents were furious.
No flames can kill prions.
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.
a failing one, a subspecies teanominus partius has evolved and is slowly choking out the main species. its sad beacuse teanominus partius cannot survive without the host species. We are watching evolution at work here people.
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.
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.
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.
I agree - it is important to get away from the concept of evolution as being life-based, and recognise that evolution is an emergent property of a system.
For the prion example, the key is to remember that incorrectly folded proteins accumulate and cause the prion disease - the proteins themselves are not the disease, but the accumulation is. If one folding configuration is more likely to cause other proteins to fold incorrectly, then it is natural to assume that this configuration will become eventually dominant, until a more effective configuration arises. Also, the accumulation of protein causes a feedback loop, increasing the likelihood of further malign folding. Presumably, the folding is sometimes imperfect, so this is the source of the all important mutations causing variety. Without the accumulation, I would presume that the configuration of folding has a benign effect.
So, folding configurations that increase the rate of malign folds or increase the rate of accumulation would be more successful in this feedback loop. Does this really justify the tag 'evolutionary'? It just seems that the natural progression of the disease causes what appears to be a natural selection process, but it's not clear at what point we should distinguish between a feedback loop and an evolutionary process, if indeed they are actually one and the same thing...
And it is not surprising that many seem to require unnatural diets to occur (feeding meat to herbivores, forcing cannibalism where this is not found in nature, etc). For whatever prions might occur under normal circumstances, evolution has probably equipped us to stop the chain reaction, or deal with the products. Ones that can only spread under circumstances not found in nature OTOH, are "new" to the body and some of them may therefore accumulate in dangerous amounts.
sudo ergo sum
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.
ideopath @ play
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.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
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.)
Did you know 80 to 90% of the moderators on slashdot wouldn't recognize a troll even if one dragged them under a bridge.
Possible maybe, but likely? There is probably a reason that DNA (and RNA) are DNA and RNA and not something else. It's the same reason by complex chemicals/life chemicals are mostly constructed around Carbon. Carbon has lots of free valences, which allow it to act like a universal lego-block. Other elements, just don't have as much flexibility. It's why it's entirely unlikely that you will ever see something that can be classified as life that isn't carbon-based. Other elements just can't be as flexible as Carbon.
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It ate all of the Not-So Grand Canyons?
If I have been able to see further than others, it is because I bought a pair of binoculars.
I'm sure that enough heat*time will do it, but I suspect that your food isn't food at that point. Autoclaving is insufficient to destroy prions on surgical instruments, for instance.
A.
...bringing you cynical quips since 1998
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.
Breaking Into the Industry - A development log about starting a game studio.
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.)
Breaking Into the Industry - A development log about starting a game studio.
In "Energy Flow In Biology" Harold Morowitz posits that an open system between an energy source and an energy sink, containing such elements as can form a variety of bonds and forms, will absorb energy, and form compounds that will persist in that state for a time in inverse proportion to how much energy is required to maintain the state. Increasingly complex forms can be created from those simpler forms if they persist long enough. Those more complex forms can have variations in their subunits locations and forms relative to the components from which it is built. This is the first chapter. The rest of the book is a bit of physics and a great deal of physical chemistry showing why the proportions of organics found on Earth as inevitable given the conditions of the Earth's environment and the combination of elements from which is is made.
The evolution part applies to the first chapter though. Some compounds self-catalyze, producing more. Some catalysts form that produce other products, but only do so when the first of those products form. Variations such as radicals appearing in different places on a benzene ring produce different forms, and catalysis can cause this to happen step by step, forcing the radical to 'march' around the ring.
Increasing complexity, with variations in forms of those increasingly complex forms, each of which have more or less ability to contribute to furthering these phenomena, that pretty much describes what life does. Maintaining itself at a level of complexity above the environment (read that 'maintaining itself in a state of negentropy) for a time, using the incoming energy, described something much like how life appears in contrast to its environment.
Again, this is all based on physical and organic chemistry, pre-biology. It's only logical to expect the activities of living things to mirror the activities of their non-living constituents. No, those compounds are not alive, but if they couldn't do those things, neither could life.
A marker then for life might be detection of compounds that carry out some functions we see in life, and an environment that allows them to increase in amount and in complexity. Where then do we put the dividing line between life and non? If we can objectively define and predict an emergent property that appears at a certain point in the growing complexity of the chemical soup that is characterized by a behavior which is necessary for life but is absent in the pre-living material, we might be able to describe that sufficiently to say it's one definition of life.
If it hasn't occurred to you before, it should now: a different environment and collection of compounds might also produce organics (or the equivalent based on other elements) will produce different results. If life, that will be different. Taking the definition from one situation is hobbling yourself when it comes to discovering other forms of life. It might also occur to you that there is no time scales associated with any of this. If we then take the broader view and don't limit 'life' to the result, but include it in the components, we can at least start with a statement about a component being 'alive enough to consider that aspect'.
We need as broad a view as possible so we will be able to recognize it when we see it elsewhere. A part of science is dedicated to looking for it. With our present definitions, which should be stated "Earth-like life" rather than simple "life", we are primed to not detect any forms of it which we could imagine but which differ significantly from Earth forms.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
Dear Sir, what does God need with a cheezburger?
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
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.)
I think we've pushed this "anyone can grow up to be president" thing too far.