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New Letters Added To the Genetic Alphabet
An anonymous reader writes with this excerpt from Quanta Magazine: [A]fter decades of work, [organic chemist Steven] Benner's team has synthesized artificially enhanced DNA that functions much like ordinary DNA, if not better. In two papers published in the Journal of the American Chemical Society last month, the researchers have shown that two synthetic nucleotides called P and Z fit seamlessly into DNA's helical structure, maintaining the natural shape of DNA. Moreover, DNA sequences incorporating these letters can evolve just like traditional DNA, a first for an expanded genetic alphabet.
In fact, the article continues, these new nucleotides can actually outperform their natural counterparts: "When challenged to evolve a segment that selectively binds to cancer cells, DNA sequences using P and Z did better than those without."
That's all I've got to say on the subject - even if I knew much about it the likely outcomes are speculative. Though not the predictable protests.
This is at least a bit over a year old.
Nature had a good publication on this a bit (same research group) over a year ago.
http://www.nature.com/news/fir...
For every problem, there is at least one solution that is simple, neat, and wrong.
Because nature is a slacker and it does the bare minimum when pushed until it's pushed again? That's how evolution works bro.
it's alive.
It is not clear how the new nucleotides act when transcribing proteins but assuming its at least as efficient as the 4 letter code it could be a very interesting option for artificial viruses. A virus engineered to be totally dependent on the new nucleotides could be used much more safely even inside humans where there is no supply of them, they could infect the cells, produce proteins and a huge immune response but not a single copy of their genetic material could be produced. Also in a controlled environment they would thrive (cheap production?) but without P-Z no danger of new virus production so safety would not need to be as strict.
Applications on real organisms probably will take much longer time, but the simplicity of virus would make it a natural first step.
Or because they don't actually work in a living organism for any length of time, where time could be a few cell divisions to generations.
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They say the new DNA outperforms the standard DNA in evolving to meet the researcher's criteria. That means it changes more easily. In other words, it's less stable.
In most situations, what we want is stability. Nature needs some ability to mutate and evolve, but considering that the wrong mutations result in cancer and death, too high of a mutation rate leads to failure. I suspect this is particularly true in long-lived larger organisms.
Of course we did not evolve wheels neither. Almost all animals above worms are torii topologically. (The digestive tract is the hole in the ring). There is one bacteria that has a free spinning flagellum. So nature started on that kind of disjoint topology, but could not scale it beyond bacteria. Two symbiotic animals one providing a wheel with shaft and another providing the bearing, together could have formed a wheeled animal. But that never happened, there is no path in the fitness landscape to achieve that configuration. Is it something fundamental like this that prevented six letter DNA
Or, more prosaically, the drawbacks outweigh the benefits. After all computers use binary not tertiary numbers. The four letter DNA is technically a binary system. Two pairs. So even if this thing escapes the laboratory it won't thrive in the wild and wipe out all the present forms of life Comforting if it is so.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
...by sequencing cancer.
now we need to go OSS in diesel cars
Probably because nature's goal isn't a trivial experiment and there are many other factors we don't understand because we haven't had millions of years to try out the other DNA form in actual living organisms.
It probably has been tried in single celled organisms many millions of times, and there is probably a very good reason why it didn't stick.
while(1) attack(People.Sandy);
So you're saying they might have created RNA Against Humanity?
Are YOU using the TOOL, or is the TOOL using YOU? Think about it!
The main reason this hasn't evolved is the "lock-in" effect. There is a lot of cellular infrastructure (ribosomes, DNA repair mechanisms, etc.) that work with the current ATCG alphabet. If you add letters to the alphabet, you would need to simultaneously change all the complicated infrastructure. Evolution doesn't work like that.
This is part of a broader DARPA driven effort to expand what biology is capable of.
The end goal is to be able to create new materials (better fuels, medicines, building materials, etc) using biology. This requires expanding the "toolkit" biology uses to incorporate biologically incompatible elements, chemicals and processes.
So, starting from the end: We want a better biofuel. To do that, we want proteins that can better incorporate inorganic catalysts and work at higher energies than existing biology. To do that, we need different amino acids and protein construction machinery. To do that, we want to expand DNA to code for these new amino acids.
This is a "good" DARPA project in that we're not able to do all of this yet. What this means is that technology is pushed forward significantly, and we're able to clearly identify the real challenges.
Have gnu, will travel.
Of course there will be protests. So many people are using software at home to manipulate their genes as 2-bit values. This is basically DRM, or at least until people go back and fix all their code, which might even be technically illegal for them to do. Fuck that! We need to take to the streets, now!
"Believe me!" -- Donald Trump
___
Maybe it never tried.
That and also more importantly: because nature's idea of "better" is almost never the same as our idea of "better." I think it's wonderful that the performance example that they used, happened to be binding to cancer cells. If cancer doesn't illustrate the vast gulf between us and it, I don't know what does!
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If we replaced our DNA and RNA with these new letters, and updated all our DNA and RNA related proteins to use those letters instead, we should be immune to any virus. Of course, I don't think we could actually pull off such a change since we'd have to change so many proteins as well.
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programs evolve. Haven't you seen a "hello world" app like a single cell amoeba grow into something like libre office? Or I guess that is really intelligent design 8)
The 64 three letter codons specify 20 amino acids and punctuation. For some amino acids the third element of the codon doesn't matter or has couple redundancies. This suggest an earlier two element codon with 15 amino acids or less.
Basically because P and Z aren't commonly available in food, so you'd need to build them each time you used them. Not an energetically favorable approach. (This also tends to act to confine the altered organizims into places where the lab supplies the needed supplements.)
I think we've pushed this "anyone can grow up to be president" thing too far.
Because we don't have proper, easy to do and efficient while running, code reuse. The coding is this world is 'pre-industrialisation' era where the guilds are companies and noone has created simple stuff like an m10 bolt. No efficient standards.
nosig today
Look. All I want is that colour changing thing from cuttlefish, and to glow in the dark. Get back in the lab and let me know when it's ready. I'll pay the delivery boy at the door.
Love without logic is insanity. And vice versa.
Basically because P and Z aren't commonly available in food,...
No, but they are found in ketracel white,
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