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Medicine Science

Zebrafish Regenerative Ability May Lead To Help In Humans 106

esocid tips us to news out of Duke University Medical Center, where researchers have discovered a type of microRNA that is related to the ability of zebrafish to regenerate lost or damaged organs. This is the result of a study initiated after it was discovered that zebrafish were able to recover from "massive injury" to the heart through their own regenerative biology. The scientists hope to be able to use this information to bring about similar healing in humans. Zebrafish have also been helpful in cancer research. "In zebrafish, one or more microRNAs appear to be important to keep regeneration on hold until the fish needs new tissue, the Duke researchers say. In response to an injury, the fish then damp down levels of these microRNAs to aid regrowth. Poss and many other cell biologists believe that mammals may have the same tissue regeneration capability as zebrafish, salamanders and newts, but that it is locked away somewhere in our genome, silenced in the course of evolution."
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Zebrafish Regenerative Ability May Lead To Help In Humans

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  • heh (Score:5, Funny)

    by ionix5891 ( 1228718 ) on Sunday March 16, 2008 @12:02PM (#22765634)
    if i had a tail i'll play with it all day...
    • Re:heh (Score:5, Funny)

      by CRCulver ( 715279 ) <> on Sunday March 16, 2008 @12:05PM (#22765648) Homepage
      If you know the etymology of Latin "penis", then your comment ends up saying something more than you probably intended.
      • by pxc ( 938367 )

        1676, perhaps from Fr. pénis or directly from L. penis "penis," earlier "tail" (cf. Eng. tail in both senses, the sexual one slang), from PIE *pes-/*pesos- "penis" (cf. Skt. pasas-, Gk. peos, posthe "penis," probably also O.E. fæsl "progeny, offspring," O.N. fösull, Ger. Fasel "young of animals, brood"). The proper plural is penes. The adj. is penial. In psychological writing, penis envy is attested from 1924.

        • The proper plural is penes.

          It's one thing to know more than I can understand, but now I've learnt this, I'm just confused to where and when to apply this knowledge.
  • This reminds me of that godawful late Beowulf Shaeffer story by Larry Niven "Procrustes" (collected in Crashlander [] ) where someone loses their head and an autodoc manages to grow one back. I mention this not hoping anyone would go read the story, but to provide a forum where other people who lost hours of their lives to late Niven can express their feelings and frustrations to a sympathic audience of people who did the same.
  • after all my drinking sessions I now get a healthy liver and then get eaten by a lion.
    • by arivanov ( 12034 )
      That and walking at an angle based on your social rank. I do not have zebrafish nowdays, but IIRC they swim at different angles with the ones on the bottom of the society ladder at the steepest angle and the dominant one in the tank swimming nearly horisontally.
    • Could be worse. Instead of zebrafish, you could have a bananafish problem [].
  • by nguy ( 1207026 ) on Sunday March 16, 2008 @12:14PM (#22765708)
    Human life expectancy is quite long by animal standards, so it seems like we probably just don't need this anymore. On the other hand, there are usually tradeoffs with these kinds of mechanisms, and turning it on again may have rather negative side-effects.
    • by gravesb ( 967413 ) on Sunday March 16, 2008 @12:17PM (#22765730) Homepage
      Exactly. There must be some evolutionary reason to turn it off, as it seems that this gene, in and of itself, would lead to sturdier off-spring, and thus propagate. It would be interesting to know why it got turned off, though. Rampant cancer, maybe?
      • Homeotherms (Score:5, Interesting)

        by overshoot ( 39700 ) on Sunday March 16, 2008 @12:27PM (#22765792)
        Rampant cancer, maybe?

        That would be my guess. There's a good bit of research where they tinkered with mouse genes to accelerate or slow telomere erosion, and found that the natural mouse is pretty close to the maximum lifespan possible. Faster erosion causes the mice die of old age sooner, but slower erosion results in more cancer deaths.

        Regeneration may well have similar costs. Since all of the natural regenerators are poikilotherms, I would speculate that their overall lower metabolic rate has less risk of cancer. Giving up regeneration may well be the price we pay for warm blood.

        • Re:Homeotherms (Score:5, Insightful)

          by ScrewMaster ( 602015 ) on Sunday March 16, 2008 @12:34PM (#22765830)
          True, but on the other hand, if we are able to reactivate an ancient yet problematic self-repair mechanism, there remains the possibility that we might fix it. Evolution doesn't guarantee optimal solutions by any means.
          • by 11223 ( 201561 ) on Sunday March 16, 2008 @04:14PM (#22767320)
            Yeah, I saw that episode of SG: Atlantis. It never ends well.
          • Exactly. Just because it wasn't evolutionary adaptive at the time doesn't mean it isn't helpful now. Our environment has changed quite a bit since we our genetics (supposedly) found it more adaptive to turn the trait off. And if we can activate it in the right situation, we're set.
            • by nguy ( 1207026 )
              It's not clear to me how extending life far beyond the reproductive age is any more adaptive today than it was 50000 years ago. Even healthy folks rarely reproduce past 40, and rarely contribute productively past 70. You may not want to die or grow old, but from the point of view of adaptation, a life span of 70 years may still be optimal.
              • It doesn't matter. The moment humans began to care for other members of their society survival of the fittest no long applied. What we want is far more relevant than what is evolutionarily beneficial to our species.
                • The moment humans began to care for other members of their society survival of the fittest no long applied.

                  Incorrect. What actually happened is that the definition of "fit" began including getting people to like you more than it did previously.

                  "Survival of the fittest" is an oxymoron and therefore always true, so long as something survives, because the definition of "fit" is "that which survives", so the saying translates to: "Survival of that which survives". The only set of circumstances in which it

                • by nguy ( 1207026 )
                  The moment humans began to care for other members of their society survival of the fittest no long applied. What we want is far more relevant than what is evolutionarily beneficial to our species.

                  Not at all. We are subject to evolutionary constraints just like any other species; it just doesn't work in the simplistic and naive way you think it does. Selection may well happen at the whole species level, or at the society level.

                  Some societies are quickly eliminating themselves through low birth rates and li
        • Probably the best bet is to turn it on temporarily in a limited location.
          • That's usually the way it's done in most science-fiction stories, anyway. Does make the most sense, although it would be cool to be like the guy that instantly regenerates in the movie Silent Rage. Well ... minus the murderous psychopathy, anyway.
        • Yes there may be trade offs that doesn't reduce its worth. If its die from wounds now or cancer later i'd be okay with cancer later.
      • by nguy ( 1207026 ) on Sunday March 16, 2008 @12:31PM (#22765822)
        Cancer is a likely risk. I doubt it's rampant, though; just enough to make it problematic.

        There is one ray of hope: some of these genes may have been turned off not because they are harmful, but because they use energy and have been made largely redundant. If you have good eyes and a good brain, for example, you are less prone to injury. Since energy isn't a problem anymore, reenabling these genes may make you both slim and healthy. It's a possibility, but I still wouldn't get my hopes up...
      • I dunno. From what I've learned, you can't give reason to evolution. Perhaps there was a different characteristic that provided better fitness to an individual, but that same individual lacked proper regenerative capabilities. No real reason for it to happen, it just did.
      • Evolution does not produce optimal individuals, it produces optimal[1] populations. It is against the interests of a species (from an evolutionary perspective) for individuals to live forever. If individuals live forever there is no evolution of the species because there is no change. If there is no change, then environmental changes can cause the extinction of the species.

        Even if the self-repair has no side effects then it will likely lead to extinction of the species if it doesn't have the intellige

        • Well, there are a few things to take into consideration here. One is that procreation won't stop just because dying stops. Which will mean that there are still opportunities for the population to evolve.
          The other on is that longer lifespans and regenerative abilities would definitely help us in the conquering of space, which is an evolutionary advantage compared to staying around here waiting for the next ELE to come around.
          And since we as a species have the life expectancy of about (pulling random but pl
    • Well ... assuming this ability still exists in humans, and further assuming that we find a way to turn it on, there are situations where one might be willing to accept an increased risk of cancer or some other infirmity. I mean, suppose you were someone that had had his penis shot off: wouldn't you take the chance of a little cancer to get your rod back?
      • I mean, suppose you were someone that had had his penis shot off: wouldn't you take the chance of a little cancer to get your rod back?

        OMG, I already can imagine the spam:
        Turn on regeneration in your penis, make it grow 5 inches, only 99$, minimal cancer risk, money back guaranteed.
      • I'm pretty sure that a fair number of cancer patients would part with their organs in a second if it meant another thirty to forty years. Living without sex and peeing awkwardly may sound awful, but a slow death isn't so great either.
    • It seems likely that such a mechanism would be used mostly later in life ... after the reproductive years have passed. And so, evolution would not likely promote or demote this trait.
      • It seems likely that such a mechanism would be used mostly later in life ... after the reproductive years have passed. And so, evolution would not likely promote or demote this trait.

        Grandparents help in the raising of their childrens children. I don't think being too old to reproduce isolates you from evolution. And how old would a man have to be to not become a parent?

        • Well right now the main detriment that aging brings to the table is cardiovascular health, so after a certain age (depending on the person) they're no longer healthy enough to have sex. I'm curious if regeneration would perhaps mitigate this factor, as cardiac cells could conceivably be regenerated to undo the effects of aging as well.
  • by overshoot ( 39700 ) on Sunday March 16, 2008 @12:20PM (#22765748)
    ... what is the evolutionary benefit that mammals get from not regenerating?

    I'm reminded of a story from Analog in the 60s, where they figure out how to stimulate toot regeneration. Except that, once the technique has been in use for a while, they find out that it doesn't stop producing new teeth ...

    • Re: (Score:3, Interesting)

      by CRCulver ( 715279 )

      Interesting. In Gene Wolfe's novella Seven American Nights (collected in The Island of Doctor Death [] ), the inhabitants of a post-apocalyptic America where some kind of nuclear radiation accident had occured repulse the narrator with their extra teeth. Perhaps your story in Analog is where Wolfe got the idea from?

      This Slashdot story seems to be bringing up more associations with science fiction than usual.

      • by hicksw ( 716194 )
        Like "End of Summer", by Algis Budrys, Astounding Science Fiction, November 1954?

        A cure for cancer/death also cured long term memory.
    • Re: (Score:3, Insightful)

      by FatalChaos ( 911012 )
      Well one problem with regenerating is that it probably requires a LOT of energy, which would speed up metabolism a lot. Maybe our regenerating ancestors couldn't find enough food to support the feature, and plus if food is scarce and you are pooling a lot of energy to support this regeneration, this might lower your overall muscle mass or brain size, etc.
      • Perhaps there is something to the fact that, by and large, animals who can regenerate profoundly are cold-blooded, and no natural warm-blooded animals I'm aware of can do that. We already expend huge amounts of energy just keeping ourselves warm. Perhaps the regeneration faded with the increased energy expenditure from warm-bloodedness.

    • I'm reminded of a story from Analog in the 60s, where they figure out how to stimulate toot regeneration

      Nothing special about that. I do it with pepperoni pizza all the time. Legumes also work well.
    • by vertinox ( 846076 ) on Sunday March 16, 2008 @02:03PM (#22766450)
      ... what is the evolutionary benefit that mammals get from not regenerating?

      Given the hostile everyday nature of the wild, an animal has a far better chance of surviving in the long run if he gets back on his feet after an injury even if it isn't a full one. Its far quicker for scar tissue to reform than it is to recreate all the tissue back in a perfect fashion.

      So rather having an open wound for several weeks on on end, a wild mammal would have a scab within 24 hours and then later initial scar tissue within a week
    • by Epistax ( 544591 )
      ... what is the evolutionary benefit that mammals get from not regenerating?

      Well, if the typical regeneration benefit would come to someone who is too old or otherwise too hurt to possibly be a parent, there's no way for a genetic advantage to pass along. I don't know if that's what's going on here.

      Or conversely, perhaps the regeneration scheme has a better chance of screwing things up than that of a freak accident occurring. The opposite might be true for a zebra fish, thus it could develop.

    • The resources devoted to being able to regenerate could be used to avoid injury, instead. Even if you heal quickly and from grievous injuries, it's better not to get hurt in the first place--especially if the lack of regeneration means you're better able to avoid mishaps that would kill you instantly.
    • Evolution works on species, not on individuals. It doesn't select individuals likely to survive, it selects species. For evolution to work, it needs some random elements introduced into the genes regularly, which means it favours short-lived creates since they go through more evolutionary cycles in a given amount of time. If individuals live longer then competing species will become better adapted to their evolutionary niche. At this point the species dies out in most cases. Intelligence skews this si
    • Re: (Score:2, Funny)

      by jdelisle ( 582839 )

      I'm reminded of a story from Analog in the 60s, where they figure out how to stimulate toot regeneration.
      A can of beans, perhaps?
    • ... what is the evolutionary benefit that mammals get from not regenerating?

      What evolutionary benefit do you get from not being able to produce your own vitamin C ? What evolutionary benefit do people get from hereditary illnesses ? Evolution doesn't neccessarily weed out harmful mutations if they aren't harmful enough; so perhaps we simply got unlucky.

  • by pizzach ( 1011925 ) <> on Sunday March 16, 2008 @12:20PM (#22765750) Homepage
    AGH! I have ears regenerating all over my body! Get them off!
    • we could create one heard of cows and just chop bits off at intervals.. then just wait for it to regrow! very handy if you get a really tasty piece of beef...
  • by temcat ( 873475 ) on Sunday March 16, 2008 @12:22PM (#22765758)
    In my fairly limited understanding of evolution theory, the features that help to survive are retained through the natural selection. Regeneration ability seems to help to survive - why would it be lost then? Could it be that the time required to naturally regenerate was so long that the animal weakened by the injury died anyway by natural (lack of food and/or water access, climatic factors) or violent (predators) death?
    • Evolution isn't really about survival into old age, more survival to an age where reproduction is possible -- just ask a male praying mantis. So one possible reason why regeneration abilities didn't survive is that it mainly benefits older animals who are less likely to be generating off-springs.
    • The problem is cancer.

      Regeneration is ... massive and nearly unlimited cell growth
      Cancer is ... massive and unlimited cell growth

      A tiny mistake in regeneration will therefore cause cancer very reliably, and quite deadly. In order to let people get really old, cancer must be prevented (most dogs could easily live up to 25, with reduced bodily function, instead of 15 without cancer, but they have more chance of recovering from large injuries during those 15 years).

      There is another problem. Another very import
      • by ScrewMaster ( 602015 ) on Sunday March 16, 2008 @01:32PM (#22766212)
        "Forever young" this is not.

        Maybe not ... but as another poster pointed out, if this capability were activated on a temporary basis solely for the purpose of regenerating lost or damaged tissue, it would prove invaluable. Hell, if this did become practical, one could chop out diseased parts of an organ and simply regenerate them. Transplants could become a thing of the past. Lose an extremity? Regrow it!
        • And in the process turn any not-yet-cancerous warts into footballs ...
        • Mod parent up! It would be great to turn this off or on as needed.

          That's apparently what the zebra fish do: the regen mechanism is dormant until they get injured and need to use it; then they "release control art restriction level" and allow the mechanism to work.

          I'm guessing the mechanism either never evolved in mammals, or else something about our biochemistry means whatever chemicals the fish use to either inhibit or activate the mechanism become unstable, thus leading to uncontrolled regen and cancer.
    • Genome has interrelated genes, so turning regeneration on can be beneficial, but it also can turn on undesirable genes/RNA.Not necessary cancer but it may be something like 20% more susceptibility to malaria or something selected against in the far past.
      it could be something which monkeys had problem with or entirely freak mutation which had more survival potential.
      Its like the case with internal Vitamin C production which humans lack,but goats possess.
    • Re: (Score:2, Insightful)

      by maxume ( 22995 )
      Evolution doesn't happen along cleanly defined lines; lots of people are trotting out cancer as an easy problem to relate to regeneration, but it doesn't need to be anywhere near that complex. It could be as simple as the developments leading to warm blooded metabolism accidentally turning off regeneration, so as those organisms took over niches where being exothermic was a big advantage, regeneration disappeared.

      So the breakage of the regeneration mechanism could be completely incidental, even if was advan
  • It will end in pain. Trust me on this one. The world really doesn't need a Zebrafishman.
  • miRNA (Score:1, Informative)

    by Anonymous Coward
    FYI, as I guess this is not going to be obvious to everyone reading the article - microRNAs are a type of small RNA that are currently very popular in biology because they allow to "turn off" genes. Basically, microRNAs as well as related types of small RNA molecules switch off the synthesis of the product of a gene. Obviously, Wikipedia is going to offer more detail... Look up "RNA interference".
  • Here they come... "But why would evolution get rid of a useful trait!". I'll tell you one possible reason why - random mutation. Offspring mutates to inactive "regen gene". Offspring lives. Bingo - whole line of offspring with inactive gene. It could also be that other mutations mitigated the benefit of this gene making it of small use and hence when it went away it didn't, in practice, limit viability of the offspring without it. For example (I'm making this up, but sounds plausible to me), cold-blo
  • The regenerative ability doesn't help a zebrafish when swallowed up by a larger fish.
  • Speed (Score:2, Interesting)

    by KillaGouge ( 973562 )
    I always though it was because that it is simply faster and easier to let the body scab over the wound then to try to let the internal structure regenerate. So the human body developed the scabbing ability so that humans who did get injured could quickly escape whatever injured them.
    • I think it's safe to say that both scabbing/scarring and regeneration are both damn slow compared to the mountain lion that just bit off your hand.
  • Plot of next Spiderman sequel.
  • Um... yeah. Mice have already been discovered that regenerate. (The MRL strain)

    Several years ago.

    It was on /.

  • Axolotls do possess regenerating abilities as well.
  • "The doctor gave me a pill, and I grew a new kidney! The doctor gave me a pill, and I grew a new kidney!"

    "Fully functional?"

    "Fully functional!"
  • Has been used to help regerate small sections of missing fingers/toes etc..... []

  • Most mammals can do it naturally when they're young, but the ability disappears almost completely with age. However, even older rats have been induced to regenerate limbs. There seems to be a critical level of nerve density required to trigger regeneration (actually, it looks like it might not be the nerves themselves, but rather the Schwann bodies surrounding the nerves). In mammals, the density is too low. Adding a very small DC current will cause certain cells to dedifferentiate into at least pluripotent

Life in the state of nature is solitary, poor, nasty, brutish, and short. - Thomas Hobbes, Leviathan