May 26 2008

Resurrecting the Tasmanian Tiger

This is a cool story from the BBC. Australian scientists have been able to extract a cartilage gene from DNA taken from a preserved specimen of Tasmanian tiger 100 years old. They then placed that gene in a mouse, and the gene worked pretty much as the native mouse gene would.

Any resurrection of DNA from an extinct species provokes images of Jurassic Park. However, this is a long way from once again having Tasmanian tigers in zoos, or the wild. The Tasmanian tiger, or Thylacine, went extinct due to hunting, with the last specimen dying in 1933. Interestingly, there continues to be local legends that the animals still exist in the wild. It is sort-of their Bigfoot – the evidence consists of sounds heard in the wild, trace evidence, and tall tales.  But, alas, the evidence strongly suggests that the Thylacine is no more.


However, several museums have Thylacine tissue preserved in alcohol. This allowed the researchers to collect viable DNA. As these genetic techniques are developed further it is theoretically possible to resurrect an entire Thylacine through cloning. It remains to be seen of the DNA is complete and viable enough, but this study is encouraging.

Going forward, this technology also means that we can preserve endangered species, perhaps by freezing tissue, for later cloning. We have already done this for plants, creating several massive seed banks. Perhaps we can create a biodiversity preservation bank for endangered animals as well.

What about species that went extinct further in the past? The prospects get quickly more dim as we go back in time. We can extract Neanderthal and Mammoth DNA from specimens. Perhaps it might be possible to clone animals from thousands of years ago – but this will be much more difficult. It remains to be seen if this is possible, but we may find out in our lifetimes.

But, unfortunately, going back millions of years is almost certainly not possible. DNA simply does not survive for that long. We will not be seeing T-Rexes in Jurassic Park type zoos in the foreseeable future. This may never be possible, and if it is it will require techniques not yet theorized.

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19 responses so far

19 Responses to “Resurrecting the Tasmanian Tiger”

  1. Fred Cunninghamon 26 May 2008 at 2:16 pm

    A Mammoth sounds great but a Neanderthal would sure raise some ethical questions.

  2. deciuson 26 May 2008 at 3:46 pm

    I think the invaluable data that could be extracted from the “resurrection” of a Neanderthal should override all ethical questions.
    For instance, I doubt that there would be other ways to put to rest the diatribe as to whether the Neanderthals were capable of speech, or of interbreeding with Cro-Magnons.
    It’s also difficult to believe that an individual brought to life would object to his own existence.

  3. Apopheniaon 26 May 2008 at 4:33 pm

    decius,
    although resurrecting Neanderthals would undeniably provide answers, I doubt the ethical concerns could so easily be overridden. Creating a potentially sentient being for the purpose of research is an ethical minefield. There is a procedural catch 22; an imperfect cloning method could result in a baby Neanderthal with unforeseen complications, and there is no way to perfect the process without trial and error.

  4. mat alfordon 26 May 2008 at 6:43 pm

    mmmmm……mammothburger….

  5. Zytheranon 27 May 2008 at 1:54 am

    The ABC’s (Australian government broadcaster) Science Show had this article on their latest episode a few days ago. Audio is available now, transcript in a few days.
    http://www.abc.net.au/rn/scienceshow/stories/2008/2250210.htm#transcript

    As mentioned by those interviewed, they only inserted one gene..out of tens of thousands.
    There are very serious challenges with assembling all the genes, and their non-coding information in the correct sequence, to be actually able to create a whole creature.

  6. dhawkins1234on 27 May 2008 at 5:30 am

    Before Neurologica went down, the entire content of your posts was in the rss feed, so it was possible to read it within a feed reader. Now only the first couple of paragraphs show up. Was this change intentional and permanent, or was a setting accidentally changed in the process of getting the site back up?

  7. Steven Novellaon 27 May 2008 at 7:49 am

    regarding the RSS – there is a setting to show either just what is “above the fold” or the entire entry. The setting must have been changed – it was not intentional. I will ask my webmaster to change it back. Thanks for pointing it out.

  8. Chris Hylandon 27 May 2008 at 10:48 am

    Interesting post :)

    I really enjoy the fact that there is a blog devoted to neuroscience — maybe have some more interesting articles about the brain covering “interesting but cool things people don’t often know” or somesuch? :)

    I enjoy everything SGU, and ScienceBlogs and Ness! ;) I live in Original England…

    ~Chris

  9. daedalus2uon 27 May 2008 at 11:50 am

    One way that genomes is sequenced these days is to break the DNA into small pieces, sequence each piece and then fit the pieces together by matching areas where they overlap.

    In principle this could be done with degraded DNA and provided that the pieces are not too small, and if some are not completely missing, it is conceivable that it could be done.

    I suspect that mammoth DNA is the one most likely to be successful. Mammoths are big, so there is a lot of source material, many of them have been frozen at pretty low temperatures since burial, which is a lot better preservation that most dinosaur DNA has experienced.

    The techniques to do this kind of sequencing effort are not really ready for prime time yet. It would be a shame to waste irreplaceable specimens with present techniques which will lose a lot of potential data.

    Attempting to clone a Neanderthal would be unethical. Maybe the genes could be analyzed to ensure they were functional. The function of non-gene coding DNA is still mostly unknown. There is no way to know if it is corrupted except by comparing it to sequences that are known to be good, and there are none available.

    A clone made with corrupted DNA doesn’t answer any useful questions about the properties of Neanderthals with intact DNA.

    It would be unethical to attempt to clone a sentient individual using DNA components not known to be intact. Once we have sufficient understanding of DNA to know that the sequences are intact, there will likely be few questions remaining that actually expression of the DNA is needed to answer.

  10. DevilsAdvocateon 27 May 2008 at 11:54 am

    I see horrible things emitting from the idea of cloning Neanderthal, namely one of those grade-Z Hollywood comedies, something like “Neander Paul” starring Paulie Shore. Darwin help us all.

  11. deciuson 27 May 2008 at 3:03 pm

    daedalus2u,

    I should have made clear that I do not advocate attempt at resuscitation from poor samples, or with techniques of dubious success.
    It isn’t inconceivable that some intact Neanderthal’s DNA may one day be extracted from a molar, or from a particularly well preserved tibia. I was assuming as much, before we even consider attempting the experiment.

    Apophenia,

    again, I should have clarified that any attempt at resuscitation should stem from established and bullet-proof cloning techniques, perhaps in a distant future when the relevant science will be confident enough.

    Once these two conditions are met, I fail to see the “ethical minefield”, except if I consider the issue from the point of view of the religious, which is anyway based on wrong premises.

    I find more objectionable the experimentation on high primates captured in the wild, than bringing a Neanderthal to life, particularly if certain conditions of fairness were to be met, by granting him/her the right of the least traumatic existence as possible, under the circumstances.

  12. deciuson 27 May 2008 at 3:42 pm

    Sorry for the mangled sentence in my previous post, I forgot to proof-read.

  13. daedalus2uon 27 May 2008 at 6:24 pm

    Background ionizing radiation is about 2.4 mSv/year. If we consider that any Neanderthal DNA is at least 25,000 years old, it has accumulated a radiation dose of at least 60 Sv. That is 10x a dose that is virtually always 100% fatal. That radiation damage to the DNA would be added to any DNA damage due to chemical or other effects.

    I consider it virtually impossible that any single cell could have sufficiently intact DNA that it could be cloned (even if we knew exactly how to do so). I am pretty sure that would be the case even if that cell had been stored under ideal conditions (i.e. frozen in LN2 below the glass transition of ice).

    The DNA from multiple cells will have to be sequenced, the sequences compared and the “correct” sequence inferred. Then the whole genome will have to be assembled from synthesized DNA pieces.

    We are still a very long way from being able to do that. It may be possible to do it at some time in the future, it won’t be possible if the best specimens are used up in useless attempts to clone from DNA that is obviously so damaged as to be non-viable.

    I see the cloning of the cartilage gene from the Tasmanian tiger as using up material that may potentially be useful in a future attempt that would have a greater chance of being successful.

  14. Ribozymeon 27 May 2008 at 6:26 pm

    Even if we could rescue a whole genome sequence and assemble it into the corresponding chromosomes, we still wouldn’t know a thing about its normal epigenetic modifications in the fertilized egg, the existing proteins and RNAs in that cell, the structure of their distributions, etc, all of which play crucial roles in the development of an embryo. Without that information, too much would be hanging in the air for it to be possible to decide whether what was obtained was a normal individual. In fact, I doubt that embryonic development would proceed all the way through if we just made educated guesses. And even if by trial and error conditions were achieved in which development would proceed all the way through birth, we could never know if the obtained individual was normal.

    As John Wilkins puts it:

    By Matt Ridley, in Time:

    … by the end of this century, if not sooner, biotechnology may have reached the point where it can take just about any DNA recipe and read off a passable 3-D interpretation of the animal it would create.

    So long as you also know the developmental machinery, the necessary ecological conditions, the structure of the cells, the maternal investment involved… in other words, if you know the facts about the structure and biology of the organism, you’ll be able to read off the structure and biology of the organism, just from the DNA. Err….

  15. Steven Novellaon 27 May 2008 at 8:04 pm

    yes – 1 gene is a long way away from a genome, and even a genome is a long way away from an embryo.

    However, we could use a relatively closely related species to infer the cellular machinery. We could, for example, clone a Tasmanian Tiger by placing its genome into a Tasmanian Devil embryo. For Mammoths we could use elephants.

  16. wertyson 27 May 2008 at 10:55 pm

    By the by, the last thylacine in captivity died because the keeper of the zoo neglected to unlock the door to its shelter overnight, and the thylacine died of exposure. Nice one…

    There have been many reported sightings of thylacines, most of which are unreliable, but a couple are quite convincing descriptions of possible thylacines in the wild. The most recent credible sighting was in 1997, and more recently some alleged photos were taken which are unconvincing. If you’ve ever been to Tasmania, you will easily accept that it may be possible for some to have survived, but there is no hard data on hair samples, scat samples or tracking by expert gamekeepers and what is known about their breeding habits and behaviour in captivity suggest that thylacines would need a wide territory to support enough of them to have survived 75 years after their accepted extinction date. Unfortunately despite the romance of the myth it fails Hume’s test for belief in miracles.

    Re the Tasmanian Devil scenario, this is unlikely as the thylacine was probably quite genetically distinct, as Devil genetic studies prompted by the occurrence of Devil Facial Tumour Disease have revealed that there is little evidence of genetic diversity, at least within the Eastern population of Devils, which are the ones most affected. Interestingly there have been six Devils identified (the so-called ‘Special Six’) which are able to mount an immune reaction to the tumour and not succumb to it. On the genetic makeup of these six devils hangs the fate of the species, as they are highly likely to become extinct within 15 years if a vaccination is not found. The facial tumour disease which has halved the population of devils in the wild within a decade (or 2 generations of devils) has been traced to a single chromosomally deficient female, and because of the lack of genetic diversity within the devil population affected, virtually every devil who contracts the tumour has died of it (apart from the special six). The tumour is spread by direct innoculation of the cells, which occurs due to the feeding and ritualistic fighting behaviours of the devils. Every case of DFTD is a clone of the original tumour, which has never been seen in any mammalian cancer before.

    Sorry to digress, but I’ve just come back from a trip to Tassie, and talked to a very knowledgeable local ranger down there !

  17. mattdickon 28 May 2008 at 11:24 am

    “It is sort-of their Bigfoot”

    I accept that the evidence of sightings is weak like the bigfoot evidence, but the one enormous difference is that Tasmanian tigers are not imaginary.

  18. Jim Shaveron 28 May 2008 at 2:57 pm

    I accept that the evidence of sightings is weak like the bigfoot evidence, but the one enormous difference is that Tasmanian tigers are not imaginary.

    True, that. But then there’s always Champ and Nessie… ;)

  19. NeuroLogica Blog » Cloning the Frozenon 06 Nov 2008 at 12:57 pm

    [...] efforts are also underway for recently extinct species, like the thylacine (Tasmanian [...]

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