By John Bohannon

When it comes to storing information, hard drives don't hold a candle to DNA. Our genetic code packs billions of gigabytes into a single gram. A mere milligram of the molecule could encode the complete text of every book in the Library of Congress and have plenty of room to spare. All of this has been mostly theoretical—until now. In a new study, researchers stored an entire genetics textbook in less than a picogram of DNA—one trillionth of a gram—an advance that could revolutionize our ability to save data.

A few teams have tried to write data into the genomes of living cells. But the approach has a couple of disadvantages. First, cells die—not a good way to lose your term paper. They also replicate, introducing new mutations over time that can change the data.

To get around these problems, a team led by George Church, a synthetic biologist at Harvard Medical School in Boston, created a DNA information-archiving system that uses no cells at all. Instead, an inkjet printer embeds short fragments of chemically synthesized DNA onto the surface of a tiny glass chip. To encode a digital file, researchers divide it into tiny blocks of data and convert these data not into the 1s and 0s of typical digital storage media, but rather into DNA’s four-letter alphabet of As, Cs, Gs, and Ts. Each DNA fragment also contains a digital "barcode" that records its location in the original file. Reading the data requires a DNA sequencer and a computer to reassemble all of the fragments in order and convert them back into digital format. The computer also corrects for errors; each block of data is replicated thousands of times so that any chance glitch can be identified and fixed by comparing it to the other copies.

To demonstrate its system in action, the team used the DNA chips to encode a genetics book co-authored by Church. It worked. After converting the book into DNA and translating it back into digital form, the team’s system had a raw error rate of only two errors per million bits, amounting to a few single-letter typos. That is on par with DVDs and far better than magnetic hard drives. And because of their tiny size, DNA chips are now the storage medium with the highest known information density, the researchers report online today in Science.

Don’t replace your flash drive with genetic material just yet, however. The cost of the DNA sequencer and other instruments "currently makes this impractical for general use," says Daniel Gibson, a synthetic biologist at the J. Craig Venter Institute in Rockville, Maryland, "but the field is moving fast and the technology will soon be cheaper, faster, and smaller." Gibson led the team that created the first completely synthetic genome, which included a "watermark" of extra data encoded into the DNA. The researchers used a three-letter coding system that is less efficient than the Church team's but has built-in safeguards to prevent living cells from translating the DNA into proteins. "If DNA is going to be used for this purpose, and outside a laboratory setting, then you would want to use DNA sequence that is least likely to be expressed in the environment," he says. Church disagrees. Unless someone deliberately "subverts" his DNA data-archiving system, he sees little danger.

ScienceNOW, the daily online news service of the journal Science

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  • Glow-in-the-dark cats

    In 2007, South Korean scientists altered a cat’s DNA to make it glow in the dark and then took that DNA and cloned other cats from it — creating a set of fluffy, <a href="http://www.theguardian.com/science/2011/sep/11/genetically-modified-glowing-cats" target="_blank">fluorescent felines</a>. Here’s how they did it: The researchers took skin cells from Turkish Angora female cats and used a virus to insert genetic instructions for making red fluorescent protein. Then they put the gene-altered nuclei into the eggs for cloning, and the cloned embryos were implanted back into the donor cats — making the cats the surrogate mothers for their own clones. What’s the point of creating a pet that doubles as a nightlight? Scientists say the ability to engineer animals with fluorescent proteins will enable them to artificially create animals with human genetic diseases.

  • Enviropig

    The <a href="http://news.nationalgeographic.com/news/2010/03/100330-bacon-pigs-enviropig-dead-http://news.nationalgeographic.com/news/2010/03/100330-bacon-pigs-enviropig-dead-zones/" target="_hplink">Enviropig</a>, or “Frankenswine,” as critics call it, is a pig that’s been genetically altered to better digest and process phosphorus. Pig manure is high in phytate, a form of phosphorus, so when farmers use the manure as fertilizer, the chemical enters the watershed and causes algae blooms that deplete oxygen in the water and kill marine life. So scientists added an E. Coli bacteria and mouse DNA to a pig embryo. This modification decreases a pig’s phosphorous output by as much as 70 percent — making the pig more environmentally friendly.

  • Pollution-fighting plants

    Scientists at the University of <a href="http://www.mnn.com/local-reports/washington" target="_hplink">Washington</a> are <a href="http://wa.water.usgs.gov/pubs/fs/fs082-98/" target="_hplink">engineering poplar trees that can clean up contamination sites</a> by absorbing groundwater pollutants through their roots. The plants then break the pollutants down into harmless byproducts that are incorporated into their roots, stems and leaves or released into the air. In laboratory tests, the transgenic plants are able to remove as much as 91 percent of trichloroethylene — the most common groundwater contaminant at U.S. Superfund sites — out of a liquid solution. Regular poplar plants removed just 3 percent of the contaminant.

  • Venomous cabbage

    Scientists have recently taken the gene that programs poison in scorpion tails and combined it with cabbage. Why would they want to create <a href="http://www.nature.com/cr/journal/v12/n2/full/7290120a.html" target="_hplink">venomous cabbage</a>? To limit pesticide use while still preventing caterpillars from damaging cabbage crops. These genetically modified cabbages produce scorpion poison that kills caterpillars when they bite leaves — but the toxin is modified so it isn’t harmful to humans.

  • Web-spinning goats

    Strong, flexible spider silk is one of the most valuable materials in nature, and it could be used to make an array of products — from artificial ligaments to parachute cords — if we could just produce it on a commercial scale. In 2000, Nexia Biotechnologies announced it had the answer: <a href="http://www.physorg.com/news194539934.html" target="_hplink">a goat that produced spiders’ web protein</a> in its milk. Researchers inserted a spiders’ dragline silk gene into the goats’ DNA in such a way that the goats would make the silk protein only in their milk. This “silk milk” could then be used to manufacture a web-like material called Biosteel.

  • Fast-growing salmon

    AquaBounty’s genetically modified salmon grows twice as fast as the conventional variety — the photo shows two same-age salmon with the genetically altered one in the rear. The company says the fish has the same flavor, texture, color and odor as a regular salmon; however, the debate continues over whether the fish is safe to eat. <a href="http://www.aquabounty.com/products/products-295.aspx" target="_hplink">Genetically engineered Atlantic salmon</a> has an added growth hormone from a Chinook salmon that allows the fish to produce growth hormone year-round. Scientists were able to keep the hormone active by using a gene from an eel-like fish called an ocean pout, which acts as an “on switch” for the hormone. If the FDA approves the sale of the salmon, it will be the first time the government has allowed modified animals to be marketed for human consumption. According to federal guidelines, the fish would not have to be labeled as genetically modified.

  • Flavr Savr tomato

    The <a href="http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.v054n04p6&fulltext=yes" target="_hplink">Flavr Savr tomato</a> was the first commercially grown genetically engineered food to be granted a license for human consumption. By adding an antisense gene, the <a href="http://www.mnn.com/local-reports/california" target="_hplink">California</a>-based company Calgene hoped to slow the ripening process of the tomato to prevent softening and rotting, while allowing the tomato to retain its natural flavor and color. The FDA approved the Flavr Savr in 1994; however, the tomatoes were so delicate that they were difficult to transport, and they were off the market by 1997. On top of production and shipping problems, the tomatoes were also reported to have a very bland taste: “The Flavr Savr tomatoes didn’t taste that good because of the variety from which they were developed. There was very little flavor to save,” said Christ Watkins, a horticulture professor at Cornell University.

  • <a href="http://www.mnn.com/green-tech/research-innovations/photos/12-bizarre-examples-of-genetic-engineering/banana-vaccines" target="_hplink"><strong>CLICK HERE</strong></a> to continue on to <a href="http://www.mnn.com" target="_hplink">Mother Nature Network</a> to see the rest of these bizarre genetically engineered creations, including <a href="http://www.mnn.com/green-tech/research-innovations/photos/12-bizarre-examples-of-genetic-engineering/banana-vaccines" target="_hplink">banana vaccines</a>, <a href="http://www.mnn.com/green-tech/research-innovations/photos/12-bizarre-examples-of-genetic-engineering/less-flatulent-cow" target="_hplink">less-flatulent cows</a>, <a href="http://www.mnn.com/green-tech/research-innovations/photos/12-bizarre-examples-of-genetic-engineering/medicinal-eggs" target="_hplink">medicinal eggs</a> and more!