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Zebrafish Regenerative Ability May Lead To Help In Humans
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."
if i had a tail i'll play with it all day...
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.
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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.
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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.
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 ...
Lacking <sarcasm> tags,
AGH! I have ears regenerating all over my body! Get them off!
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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?
Could be worse. Instead of zebrafish, you could have a bananafish problem.
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It will end in pain. Trust me on this one. The world really doesn't need a Zebrafishman.
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".
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.
Lacking <sarcasm> tags,
[Not that only ID people will wonder about this, btw, just that they love to harp on this stuff - if, indeed, the research is even correct and this is actually even in our genome somewhere.]
The regenerative ability doesn't help a zebrafish when swallowed up by a larger fish.
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.
OH shit a lion get in the car!!!!!
The problem is cancer.
... massive and nearly unlimited cell growth ... massive and unlimited cell growth
... just cut the immune system to a very low level, and disable a few cancer prevention mechanisms. Of course, make one tiny mistake, say 100 viral particles, and your patient probably won't survive.
Regeneration is
Cancer is
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 important reason human bodies don't regenerate is the immune system blocking the regeneration process. (you can prevent cuts from becoming scars with a large dose of aspirin and making sure the wound is not in contact with air (by making sure it's soaked in warm liquid for example)).
You can make regeneration easily very effective in humans
Maximum age and regeneration are forces pushing in opposite directions. You can't have your cake and eat it, I guess. This research will, if it works, present a choice to people, a short, very robust life, or a long one where you'd probably best avoid any injuries. "Forever young" this is not.
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.
"Forever young" this is 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!
Maybe not
The higher the technology, the sharper that two-edged sword.
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.
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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 advantageous, if some species with broken regeneration evolved some other mechanism that conferred a larger advantage.
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And in the process turn any not-yet-cancerous warts into footballs ...
Skin, hair, fingernails, toenails. Imagine a world if evolution decided to make it so skin didn't regenerate anymore? Or if our hair stopped growing after it was cut or lost in an accident. Recall all those moments in your life that your hair was cut/ripped out and if that hair didn't grow back, what your head would look like now??
If there were humans that were "phased out" because of their regeneration ability, it was probably because they didn't have the science/technology to stop the immediate trauma of the lost limb. So they quickly died before their body had the time to regenerate (bled to death). Hence, this species of humans wouldn't have had the quantity and lifespan to properly gain a foothold in the history of humans.
Plot of next Spiderman sequel.
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.
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We looked in the car, and there's the fucking king of the jungle! I almost shit my pants!
Assume I was drunk when I posted this.
Um... yeah. Mice have already been discovered that regenerate. (The MRL strain)
/.
Several years ago.
It was on
I recently contacted Ellen Heber-Katz, asking how the regenerating mice were progressing; they have not published anything about them in nearly two years. She replied that the mice are in fact still alive and breeding, which means that they have passed their life expectancy by at least half a year. She also said they will be releasing "lots of papers" in 2008.
Maybe, or maybe not. At this point nobody knows what would happen.
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Axolotls do possess regenerating abilities as well.
"The body may heal, but the mind is not always so resilient." -- Deus Ex: Human Revolution
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Has been used to help regerate small sections of missing fingers/toes etc.....
http://www.dailymail.co.uk/pages/live/articles/technology/technology.html?in_article_id=437215&in_page_id=1965
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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 stem cells, then redifferentiate to regenerate the lost tissues and structures. Well, that and creating an artificial neuroepidermal junction, which can be done surgically be rerouting the nerve. (In frogs, a non-mammal that cannot naturally regenerate except when young, the cells that revert to stem cells are red blood cells, oddly enough. Their red blood cells still have degenerate nuclei that can be reactivated. That seems to be a major reason why regeneration is so rare in mammals; our red blood cells don't have nuclei at all, and hence cannot be used. Fortunately, it appears that there are other cells floating about that will respond.)
Of course, until recently all of this flew completely in the face of conventional medical beliefs, so I should warn that I'm giving you the opinions of a crackpot. (A crackpot who published much of this work in journals like Nature, and whose work has been reproduced at least in part. But considering that researchers still don't seem to have caught up with his work from the 70s, I'm guessing he's still considered a crackpot.)
You, too, can read about this crazy crackpot's research in "The Body Electric", by Robert Becker and Gary Selden. And if you're interested in what I wrote above, you probably should, because I wrote from my memory of reading the book. So it's almost certain to be a horribly distorted version.