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."

wouldn't get my hopes up

[nguy]

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.

The unavoidable question is,

[overshoot]

... 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:wouldn't get my hopes up

[nguy]

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...

Re:Homeotherms

[ScrewMaster]

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.

Re:The unavoidable question is,

[FatalChaos]

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.

Re:Why would regeneration ability be lost in mamma

[ScrewMaster]

"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!

Re:Why would regeneration ability be lost in mamma

[maxume]

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.

Re:The unavoidable question is,

[vertinox]

... 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