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  #31  
Old 04-22-2012, 02:24 PM
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Synthetic DNA

Researchers have now taken a major step towards showing that alternatives can actually work as genetic material. They replaced a standard part of nucleic acids with a number of chemical relatives, and found out that they all could work. Sequence information could be shuttled back and forth between these artificial molecules and DNA, and the synthetic materials could even undergo the sort of molecular evolution that has been demonstrated using DNA and RNA.

The chemical structure of nucleic acids isn't all that complex. They consist of a long polymer of sugars, linked together by a phosphate. Hanging off each sugar is a base (A, T, C, or G). It's the order of these bases that conveys genetic information or, in the case of RNAs that can catalyze chemical reactions, form the structure needed to create a catalytically active site.

Chemically, however, just about all of these can be swapped out. The phosphate can be replaced by a sulfate and the resulting molecule can still undergo base pairing with normal nucleic acids. Other researchers have traded the sugar for related, ring-like structures. Some geneticists have even used relatives of the four standard bases that undergo base pairing that's structurally distinct. These synthetic molecules can actually be used by the normal cellular machinery if they're supplied to bacteria, creating an expanded genetic code.

Replacing the pieces of DNA

When it comes to messing with the backbone—the sugars and phosphates—it gets quite a bit harder to integrate things with actual biological systems. The enzymes that prepare and copy DNA, for example, are structured to work with sugars and phosphates. Having something that's both chemically and structurally distinct doesn't always work that well.

Rather than messing with the chemistry, the team behind the new paper decided to fix the enzymes. They started with a DNA copying enzyme, and introduced lots of random mutations, then checked for versions that would latch on to a chemical that was somewhat structurally related to the normal sugar used in DNA. After a couple rounds of this, they had an enzyme that could copy stretches of DNA into pieces of a nucleic acid that contained nothing but this sugar substitute, converting the DNA into an artificial chemical relative.

Using similar procedures, the same enzyme could be adapted to a wide variety of chemicals related to sugars. The authors picked five in total, all with features that were distinct from the normal sugars, like a double bond between carbon atoms, a fluorine replacing an oxygen, and a double-ring structure. Collectively, they termed these DNA/RNA substitutes XNAs.

Having a one-way trip from DNA to XNA wasn't all that useful for experiments, so the authors turned to an enzyme that normally converts RNA to DNA. A few rounds of random mutation, and they had a second set of enzymes that could convert XNAs back to DNA. With these tools in hand, the authors could convert any sequence into an XNA, experiment with the results, and then convert it back to DNA in order to do basic work on it, such as duplicating and sequencing it.

The process, however, was a lot more error-prone than one that relies on the typical enzymes that only work on DNA, introducing random mutations at frequencies between once every 4,000 bases to once every 500. Of course, random mutations are the raw material of evolution, so the authors decided to check out whether the XNAs could evolve new functions. They made a collection of random strings of XNAs, and selected those that stuck to a couple of substances (a protein and an RNA). Those that stuck were copied into DNA, amplified, and copied back to XNA, picking up mutations along the way. After a few rounds, they had sequences that stuck specifically.

Informative and useful

On the most basic level, the results probably won't surprise anyone with a biochemistry background. The different XNAs all look a fair bit like sugars, and mutated versions of various enzymes have been shown to be fairly flexible about what they work with in the past. And (for now at least) we're not at the point where we could grow an XNA-based cell. We don't have enzymes that can copy XNA into more XNA without going through DNA (although, reportedly, these are in the works). And the cell can't synthesize its own raw materials for XNA—they have to be supplied externally.

But none of these things are necessarily insurmountable, so it's entirely possible to imagine we could have XNA-based bacteria floating around a lab at some point in the not-too-distant future. In the meantime, the results tell us quite a bit, and could be useful.

For starters, although DNA and RNA are obviously effective carriers of genetic information and can combine that with biochemical activities, they're not the only molecules that can do so. Their role in life on Earth, then, may be a contingency. At the same time, this work suggests that life on Earth need not have started using the nucleic acids it uses now. It's entirely possible that some other related compound—one that was easier to generate from the raw materials on the early Earth—got life going, but was then replaced by RNA or DNA. That makes the job of origin-of-life researchers both easier (they don't have to limit their thinking to RNA) and harder (it's not clear what they should limit themselves to).

When it comes to life elsewhere, the options are wide open.

Back here on Earth, this also may prove very useful. There have been a number of attempts to produce nucleic-acid based therapies, and it has generally been found that skipping DNA and using some chemical relative is much more effective—the drugs last longer because the enzymes that normally break down loose DNA don't recognize the synthetic variant. The XNA-based system may allow us to produce these in huge quantities.

Science, 2012. DOI: 10.1126/science.1217622 (About DOIs).

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  #32  
Old 04-23-2012, 06:31 AM
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Originally Posted by Mike C View Post
One hanky. But I don't toss whilst dancing.
Well, at least you're not a messy tosser.
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  #33  
Old 04-23-2012, 09:14 AM
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Top Ten Transhumanist Technologies

My favourite is #9 "Virtual Reality". Game graphics are getting better and better everyday. With the introduction of software like kinect, I wonder at what point will there be software available where you have an experience greater than 3D where you feel like you are in the game. They already figured out how you can make the brain "think" that you are holding a sword when you are not. I can't remember which article that was but they were able to trick the brain. An immersive experience like that would be impressive. And I hope I get to see it in my day. Considering how fast computers have evolved I imagine it won't be too far off.

The Nano Age: Virtual Reality

Virtual Reality and it's Future
Right now, there is a great deal of hype surrounding virtual reality. The technology's present state of advancement has been overstated. Coverage in numerous magazines and newspaper articles, on TV shows, and even in TV ads suggests that virtual reality is now fully developed. Unfortunately, this is not true.

Present virtual-reality visualizations are often low-quality and cartoonish. The picture we see may be jerky and not respond quickly to our movements. Few systems allow for tactile feedback*a sense of touch. Some people even question the physiological and psychological safety of virtual reality, particularly in entertainment.

However, the future of virtual reality is important and real. We should not abandon the technology because it does not yet fit our expectations. Virtual reality is with us now in a very early and rudimentary form. Its state of development has been likened to the space program in the 1950s or microcomputers in the 1970s. We are just beginning to see the potential of virtual reality.

Faster computers, better software, and new devices to inform our senses are expected to come rapidly onto the scene, improving virtual reality and increasing its utility. Better content and new applications will rapidly emerge in the years ahead. Virtual reality will come to us over the Internet, reducing the need for complicated and expensive stand-alone equipment. Don't let the hype fool you. Virtual reality is not fully here yet, but it will become increasingly important for individuals, companies, and our society as a whole.

Let's now consider some present and future applications of virtual- reality technology. Our time frame is in the range of the next 10 years and our list is far from being all-inclusive. Virtual reality' s uses are still being explored and defined. The only thing we can be certain of is that we'll be surprised and that we must remain open to surprise.
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  #34  
Old 04-24-2012, 02:19 AM
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Originally Posted by CandraH View Post
Well, at least you're not a messy tosser.
Whoops! Scotties!

Or are you too young to remember what that is?
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  #35  
Old 04-24-2012, 02:59 AM
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Originally Posted by Mike C View Post
Whoops! Scotties!

Or are you too young to remember what that is?
Hehe. You don't think I said that by accident, do you?
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Old 04-24-2012, 06:26 AM
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A scotty should always be the target for one's 'affection'.
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  #37  
Old 04-24-2012, 11:19 PM
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If being a Transhuman means I can change into a car when I want, I'm all for it.
  #38  
Old 04-25-2012, 06:00 AM
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I am a car.

Damn, typing's tricky...
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  #39  
Old 09-12-2012, 03:57 PM
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Originally Posted by Ravenius View Post
Transhumanism, like it--hate it--, why, why not? Will you fight it when/if it happens?
Yeah nah... the problem with, for example, Apps, is they make people more efficient, more efficient at being themselves, i.e. shorter cuts to get to work on time, shorter cuts to be faster at work, shorter cuts to watch more of the same shit. Where is the serendipity?

Depending on who creates transhumanism, if it turns out to be fractal, like people are, it is only going to become more efficient at being 'it'. 'It' may not lead to any revelation, but rather some ultra-efficient fascist society; imagine how many ethnic minorities could be cleansed in that bad trip?

What 'it' needs is a bit of randomness to allow it to wander, not an optimisation wander around a point, but rather a huge leap here and there, maybe it should have some cyber-DNA?
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