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Flatworms Defy Aging Through Cell Division Tricks

Posted by Unknown on from the ail-hail-the-immortal-flatworm dept.

An anonymous reader writes "Researchers from The University of Nottingham have demonstrated how a species of flatworm overcomes the aging process to be potentially immortal. The discovery, published (abstract; full text PDF) in the Proceedings of the National Academy of Sciences, is part of a project funded by the Biotechnology and Biological Sciences Research Council and Medical Research Council and may shed light on the possibilities of alleviating aging and age-related characteristics in human cells." After finding the gene for telomerase synthesis in the worms, the researchers were able to observe that the worms "...dramatically increase the activity of this gene when they regenerate, allowing stem cells to maintain their telomeres as they divide to replace missing tissues."

26 of 106 comments (clear)

  1. Trade off by funtapaz · · Score: 2, Interesting

    I wonder what they sacrifice for this? I'm guessing they are highly prone to cancer or something. I'm nature I doubt they live long enough for problems like that to manifest.

    1. Re:Trade off by Culture20 · · Score: 5, Funny

      The trade off? They're highly prone to being a flatworm.

    2. Re:Trade off by Culture20 · · Score: 2

      There can BE only one!

      That could be problematic if flatworms regenerate their heads.

    3. Re:Trade off by EdIII · · Score: 4, Funny

      I hate to get technical, but do worms even have heads?

      Sure. It's the one the shit does not come out of.

    4. Re:Trade off by Anonymous Coward · · Score: 3, Informative

      That would be all of it.

      "Unlike other bilaterians, they have no body cavity, and no specialized circulatory and respiratory organs, which restricts them to flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion."

    5. Re:Trade off by FatdogHaiku · · Score: 4, Funny

      I hate to get technical, but do worms even have heads?

      Sure. It's the one the shit does not come out of.

      And thus they shall never be elected to public office...

      --
      You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
    6. Re:Trade off by izomiac · · Score: 5, Informative

      In humans, telomeres limit cells to ~50 divisions, which is probably related to how DNA replication is only 99.9998% accurate. After that many divisions, the genome is 0.001% different from when it started, which is one error per 10,000 base pairs, or an error in 1/3 of all genes. This is in addition to the slow rate of spontaneous mutations you accumulate over your lifetime.

      In general, fatal mutations don't matter, the stem cell will just divide again (or be dead), and cells are specialized so only a small number of genes are relevant. Furthermore, cells work together, so if two nearby cells have different lineages then they have different errors, and can likely compensate for each other. Still, you don't want too many errors in your cell replication control genes (i.e. protooncogenes ==> cancer), nor can cells function well with a tremendous number of errors (i.e. "aging"). Telomeres also help divvy-up the workload among stem cells so the most eager doesn't monopolize the work.

      For flatworms, all this likely entails a fast mutation rate. So what if 90% of its offspring die? The one that takes hold in a new host can produce thousands of offspring, and quickly changing their immunologic profile increases the odds of that.

    7. Re:Trade off by c0lo · · Score: 2

      I wonder what they sacrifice for this? I'm guessing they are highly prone to cancer or something.

      Cancer most likely: Hayflick limit.

      --
      Questions raise, answers kill. Raise questions to stay alive.
    8. Re:Trade off by turing_m · · Score: 5, Funny

      Flatworms are highly prone in general.

      --
      If I have seen further it is by stealing the Intellectual Property of giants.
    9. Re:Trade off by Daetrin · · Score: 2

      I believe there have already been very limited tests of telomerase in humans, but one of the big fears is indeed that it will increase the odds of cancer. It'll be interesting to see what happens when (if?) we have cures for most kinds of cancer.

      --
      This Space Intentionally Left Blank
    10. Re:Trade off by Zorpheus · · Score: 3, Interesting

      Very interesting. I am wondering now how Humans survive for more than 50 generations, since gametes are also fomred by cell division.

    11. Re:Trade off by Anonymous Coward · · Score: 3, Informative

      telomerase - it's just restricted to the germ line

    12. Re:Trade off by FatdogHaiku · · Score: 2

      That sir, is an insult to worms. The next time you put your face on the ground you can expect to be slapped!
      OK, maybe it will be more of a damp brushing against your face... and you may not actually notice... but you have been warned!

      --
      You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
    13. Re:Trade off by tOaOMiB · · Score: 3, Informative

      In humans, telomeres limit cells to ~50 divisions, which is probably related to how DNA replication is only 99.9998% accurate. After that many divisions, the genome is 0.001% different from when it started, which is one error per 10,000 base pairs, or an error in 1/3 of all genes. This is in addition to the slow rate of spontaneous mutations you accumulate over your lifetime.

      Where did you get your numbers? Human DNA replication (in normal cells with no damage) is 99.99999999% accurate (i.e. about 1 mutation per 10^-10 base pairs). Please do not mod parent informative for this misinformative post!

    14. Re:Trade off by izomiac · · Score: 2

      Sorry, it appears the rate was revised the year I graduated, so I was using older information (1 per 600,000). I will admit that one error per three genes from replication alone did seem too high to me. In vivo error rates seem to be one per 10^9 base pairs. Given that it's a review article, I'd have to do a lot of reading to determine how DNA packing and such affect that rate (or how they measured in vivo rates rather that ideal in vitro).

      That rate would only allow for 150 mutations per cell before hitting its telemerase limit (which most do not reach). Given the number of genes, number of cells, and sequence required for cancer to form, this number seems much too low. Thus, the environmental mutation rate must make-up the difference. For what I posted, it's not terribly relevant if the mutation was replication-induced or mutagen-induced, so I essentially conflated them for simplicity. Each organism will have very different rates, so deriving highly accurate numbers isn't necessary for explaining the general concept of the purpose of teleomeres.

  2. Disturbing by Dan+East · · Score: 5, Funny

    I find it disturbing that my tapeworms will outlive me.

    --
    Better known as 318230.
    1. Re:Disturbing by docilespelunker · · Score: 5, Funny

      Remember though, you're drinking and smoking for 2. And where drink's concerned, the little fella's basically swimming around in neat rum. (taking the assumption that you are a pirate and mostly drink rum of course)

    2. Re:Disturbing by giorgist · · Score: 2

      At one point in time ... every living thing will outlive you, think about that.

  3. Video from the researchers. by Anonymous Coward · · Score: 3, Informative

    Here is a video from the researchers themselves.
    http://www.test-tube.org.uk/videos/pages_aziz_immortal_worms.htm

  4. Re:The T-virus by c0lo · · Score: 2

    The T-Virus... is protean, changing from liquid to airborne to blood transmission, depending on its environment. It is almost impossible to kill. -- Red Queen

    Pretty close

    Jurkat cells are an immortalized line of T lymphocyte cells that are used to study a...

    Jurkat J6 cells have been found to produce a xenotropic murine leukemia virus (X-MLV) that could potentially affect experimental outcomes and infect lab technicians. This infection may also change the virulence and tropism of the virus by way of phenotypic mixing and/or recombination.

    So, only the transmission step to be solved.

    --
    Questions raise, answers kill. Raise questions to stay alive.
  5. Re:Do they keep their contacts? by c0lo · · Score: 4, Funny

    A flatworm only has, maybe, a few hundred brain cells, but if they get regenerated are they a "copy", or just "new"?

    They are a pirated copy.

    --
    Questions raise, answers kill. Raise questions to stay alive.
  6. Better memory too by G3ckoG33k · · Score: 2

    "I doubt they live long enough for problems like that to manifest."

    If you train a flatworm to pass a labyrinth and then cut the flatworm into pieces, each piece will remember the labyrinth!

    So, with this memory they don't need to live much longer, piecewise.

    They have all the nice tricks up their sleeves. The trade-off may be their looks.

  7. Ah the recipe for eternal youth! by VortexCortex · · Score: 2

    for ( i = 1; welcome( our ); ) new Imortal::FlatwormOverlords;

  8. The really interesting part by dtmos · · Score: 3, Insightful

    From the Discussion section of the linked paper:

    We find that in the model species S. mediterranea, asexual animals demonstrate the potential to maintain telomere length during regeneration. Sexual animals appear to only lengthen their telomeres through the sexual reproduction process. This finding suggests that asexual individuals will be able to avoid senescence over evolutionary timescales using telomerase, a prerequisite for the formation of an evolutionarily stable fissionating asexual lineage. [. . .] The difference we observe between asexual and sexual animals is surprising, given that sexual animals also appear to have an indefinite regenerative capacity. We conclude that either they would eventually show effects of telomere shortening or that they are able to use another chromosome end-maintenance mechanism not involving telomerase. [emphasis added.]

    So both sexual and asexual animals seem to have an indefinite regenerative capacity, but sexual animals appear not to lengthen their telomeres except through the sexual reproduction process. So how do the sexual animals attain their indefinite regenerative capacity, and why does the mechanism seem to be different from that of the asexual animals? I guess the next experiment is to start slicing up sexual animals.

  9. Immortality happening TODAY in nature. by cribera · · Score: 4, Informative

    The Immortal Life Cycle of Turritopsis, with diagrams http://9e.devbio.com/preview_article.php?ch=2&id=6 __ Inmmortal human cells. http://www.smithsonianmag.com/science-nature/Henrietta-Lacks-Immortal-Cells.html

  10. Basic intro to the planarian flatworm by nohelix · · Score: 2

    The planarian has come up several time here on /. and I thought that some people might like a quick intro these guys.

    The flatworm used in this study is the planarian S. mediterranea, a free living (i.e. non-parasitic) flatworm. They have a distinct head and tail. They have non-lensed eyes capable of detecting the direction and strength of light allowing them to move away from it. Finally, they have a bi-lobed cephalic ganglia (rudimentary brain) and a rudimentary CNS. A similar species of planarians (dorotocephala) is frequently seen in high school science class.

    There are 2 varieties of this species - one reproduces asexually while the other reproduces sexually. Both varieties are capable of complete regeneration (i.e. a full worm from almost any fragment) when cut. In both cases, the only dividing cells in the worms are stem cells called neoblasts.

    Fun Fact: Thomas Hunt Morgan did many of the initial experiments on planarians.

    -----
    Standard disclaimer: I work in a lab that uses these animal.