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Cenozoic Park: Cloning the Tasmanian Tiger
Mirk writes "The
Australian Museum
reports a breakthrough in their plans to clone the Tasmanian Tiger. The ``tiger'', actually a carnivorous marsupial, became extinct in 1936, when the last known
specimen died in captivity. Er, did I say ``extinct''?
Now it looks like what everyone thought was an extinction may be
``a 70-year hiccup'', to quote the press release. The museum's Evolutionary Biology Unit have successfully replicated individual Tasmanian Tiger genes using a process known as
PCR (Polymerase Chain Reaction)."
State funded cloning... kinda like a movie I just watched yesterday.
Get your Unix fortune now!
Couple of comments on the ever-so-brief-and-simple press release:
(1) No mention of the increasing research into why cloning large mammals if more difficult than thought. See recent New Scientist magazines for pop coverage.
(2) No mention of host animals. The Tiger can't be brought back whole and entire, something needs to act as a host - 90% close relative, 10% recovered DNA. Then work up.
(3) No mention of gene pools and viable population sizes. Pick one human - clone a breeding population from them. Fancy working with them? Didn't think so.
Still, interesting project!
... is cloning slashdot articles!
Good quote, too many chars. Seriously, the slashdot 120 char limit sucks!
All you really need to do is look at the track record of the introduction of foreign species into environments that had not evolved with them.
;) -- the introduction of the mongoose to fight the rat population in the sugar cane fields has had a negative impact on the native bird populations.
Take Hawaii (okay, share it with the rest of us
Or to quote my favorite Jeff Goldblum line:
"You were so busy trying to see if you could do it that you didn't stop to think about whether you should."
Old age and treachery almost always overcome youth and skill.
I'm capped, and yet I still whore.
DNA, as I'm sure we all know, is double stranded. One strand is a complement of the other. A complements T and C complements G. So, if one strand is:
5' ATTTC 3'
then the other strand is:
3' TAAAG 5'
The DNA is "read" from 5' to 3'. 5' and 3' refer to particular atoms on the sugar backbone that are attached to one another via a phosphate.
When DNA is replicated, you split it into two strands:
5' ATTTC 3' and 5' GAAAT 3'
(notice that the two complements read in opposite directions)
and each strand has it's complement added.
5' ATTTC 3' and 5' GAAAT 3'
3' TAAAG 3' and 3' CTTTA 5'
The problem with this is, in order for this happen to DNA, you need an RNA "primer." This primer is a complement to the beggining of what you want to replicate. So, for example, if you have (RNA bases I'm putting in bold. U is the same as T:)
UAA
floating around in solution, which compliments ATT, then any sequence beggining with ATT will be replicated, but other sequences will NOT be replicated, because no RNA primer is available to get them started.
So, if you have a whole mess of DNA, including a piece that you're interested in, which reads:
5' ATTTG (long space........) TCGTC 3'
3' TAAAC (long space........) AGGAG 5'
and you add:
TAAAC and TCGTC
You get a chain reaction; the sequence flanked by the complements of the two things you add (the sequence printed above) is replicated, and then the replication product is replicated, and so on and so on. Other sequences, which are flanked by only one compliment (only ATTTG, say) will be replicated occasionally, but there replication products cannot in turn replicate, so you get no chain reaction.
More history here.
A thermophile (heat loving organism), thermus aquaticus, provided a polymerase (an enzyme which polymerises, that is to say replicates sequences of, nucleic acids like DNA and RNA) that works extremely fast at high temperatures. In general, the higher the temperature you run a reaction at, the faster it goes. However, most biological enzymes (from, say, a person) cease to function when temperatures rise (this is one of the ways heat kills you.) Thermophiles, bacteria that live in geysers and in volcanic ocean vents, have evolved enzymes that continue to function at higher temperatures.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
I'd sure like it if a couple of species would return to existence that were obliterated earlier.
Two examples from the last several hundred years include the great auk and the passenger pigeon.
Two examples of species that humankind hunted to extinction (since they were such wonderful food sources) include the woolly mammoth and the giant sloth.
I recall an historical account of the last great auk being killed so that it could be stuffed and placed in the British museum. The collectors also took pains to destroy the last eggs in the nest at the same time. Gives you some idea of how much our views of what is fitting and proper for us to do in the world can change over a few hundred years.
Now that there are so many of us humans in a finite sized world, and our technological means of changing the world are more influential, it behoves us to give more and more thought to the consequences of our actions.
It's really only our capability for reasoning and thought that gives us a chance of beating the other animals for long term survival of our species.
"Provided by the management for your protection."
"Not every animal died because of evil humans, some died because they weren't fit to survive in this world."
Fitness to survive in the world has nothing to do with it. A meteor falls, and everything with a body mass greater than 100kg dies out. Were the larger animals less fit? A volcano erupts. A species dies. A flood wipes out a nesting ground. Chalk up another one. Human sailors bring in rats, goats and row plants, destroying practically all native flora and fauna of whole island chains.
Were any of these things destroyed because they were less fit? Of course not. If your building catches on fire, are the survivors more "fit" or are they simply lucky enough to be working on the first floor?
Despite the pitifully bad dialog of Jurassic Park, natural history does not represent some featureless plain on which species struggle against each other and the best win out. Catastrophes happen. Climates make sudden, radical shifts. Disease runs rampant. New vegetation suites are established. Chance is everywhere.
And chance is all it takes. Abandon any idea that the creatures you see around you are "better" than what came before. Different? Sure. Better? By what standards? They're here because of chance built on chance, built on chance. Feedback loops tend to enforce the status quo, keeping many species stable over millions of years (a feature generally absent for the last 12,000 years) but the best predator on Earth can't live if all the prey die and forest dwellers die when the forest goes bye.
The Thylacine happened to be a predator on an island where humans decided to raise sheep. It was fully "fit" in the environment before this point. Afterwards, it was "unfit" in the sense that it's hide was not bulletproof and it had an unfortunate predilection for traps.
Should we worry about the return of extinct species? At some point, yes, but not because some anthropomorphic "nature" selected them for extinction. We should worry because these creatures may be all too "fit" and have behaviors, breeding strategies, or feeding habits that are exceptionally successful in a modern setting.
Do you oppose the return of Grey Wolves to the Yellowstone Basin, or the reintroduction of Grizzlies to their historic range? Like the thylacine, these are creatures that have been absent from these territories for multiple generations. And the areas to which they are being "returned" have often experienced radical changes in the intervening years. Watching the ups and downs of these "reintroduction" projects should give us a good preview of the pitfalls to avoid when someone wants to put just a few Mastadons in Missouri.