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Transposable elements are the new “junk DNA”? May have function ….


From “Parasites or Not? Transposable Elements in DNA of Fruit Flies May Be Beneficial” (ScienceDaily Feb. 3, 2012), we learn,

Nearly all organisms contain pieces of DNA that do not really belong to them. These “transposable elements,” so called because they are capable of moving around within and between genomes, generally represent a drain on the host’s resources and in certain cases may lead directly to disease, e.g. when they insert themselves within an essential host gene. The factors that govern the spread of transposable elements within a population are broadly understood but many of the finer points remain unclear. New work at the University of Veterinary Medicine, Vienna (Vetmeduni Vienna) may pave the way to a more profound knowledge of the intracellular battle that is constantly being played out between the host and invading DNA.

But the battle is very complex, and one possibility that the Vetmeduni research raised is that some transposable elements are not parasites or menaces but benefactors:

the scientists found about a dozen sites of insertion that were more frequent in the population than would be expected from their age (assessed via a different method). It seems, then, that there is positive selection for transposable elements at these sites, suggesting that insertion has a beneficial effect on the host. Such an effect had previously been shown for two insertions that give increased resistance against insecticides and these cases were refound by Schlötterer’s analysis.

The functions of the genes closest to the remaining insertions are highly diverse, so how the transposable elements may benefit the flies is unclear. As Schlötterer puts it, “perhaps we shouldn’t really think of transposable elements as parasites at all. They represent a way for organisms to increase their genetic repertoire, which may be advantageous in helping them meet future challenges.”

More work is surely needed, but betting against function is looking more like a bad idea all the time.

See also: Carefully preserved jumping gene in corn shows how intelligent design produces massive changes

Liz: The "myth of the myth of junk DNA" is a . . . . MYTH! When Darwinists use this notion as a way of criticizing ID, how can you then say that ID has made this up? Where is your truth detector? Is it functioning at all well? PaV
It's time that the myth of the myth of junk DNA was put to rest. Nobody is "betting against function". Nobody ever has. Elizabeth Liddle
We have a natural explanation. Transposable elements, by their very nature, will end up in functional sequence from time to time. And on the balance of probabilities, some of those may change the function in a manner beneficial to the organism. This is precisely the same argument as we have with mutation - it is a random process with respect to need, but occasionally hits upon a beneficial change. But that is a different matter from saying that transposable elements are functional sequence - that their 'purpose' is, essentially, to cause mutations in the lineage, a fraction of which will be beneficial. Many transposable sequences are closely related to viruses - another known mutagen. While function will undoubtedly be found for more such fragments, the "parasite" hypothesis remains by far the best supported. One may hope that the whole of junk DNA may be explicable by such incremental changes in understanding, but it does not seem justifiable on present trajectories - we have about 2.8 billion base pairs per haploid genome to explain. Each transposable sequence gives us about 300. It is only functional in specific positions - the same sequence in a nonfunctional position is ... well, nonfunctional. Over half the human genome is composed of defunct transposable sequences. Unless one can come up with a better reason for the existence of those millions of repeats of essentially the same element, then they are junk, by definition. By all means keep hoping for broad 'purpose' in that fraction, but one doesn't have to be a rabid materialist to say that it's not looking likely. Chas D
As Schlötterer puts it, “perhaps we shouldn’t really think of transposable elements as parasites at all. They represent a way for organisms to increase their genetic repertoire, which may be advantageous in helping them meet future challenges.”
But, of course, this has been the prevailing ID view of transposons from the beginning. How much time has been wasted because of the "junk-DNA" view of things? And who do we thank for this view? Yes, of course, the Darwinists---or, if anyone is offended by that term, the "strictly-material evolutionists." PaV
The more we learn, the more we find that we don't understand. The questions pile up faster than the answers. That doesn't mean that we can never get to the bottom of it. But anyone who says that we're 'getting closer' to finding some natural explanation is in denial, and no one should take them seriously. Funny how every time someone finds some new feature or behavior of this thing that has no purpose, they always ask what its purpose or function is. ScottAndrews2

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