In a masterful work of “DNA origami,” researchers have created a nanoscale DNA “box” which can be opened with DNA “keys”. One day, such structures could be filled with drugs, injected into the blood, and then unlocked when and where the drugs are required [New Scientist]. Researchers say the boxes could also be used as minuscule environmental sensors that open or close in response to a stimulus, or as the logic gates of a DNA-based computer.
To accomplish this feat, described in a paper in Nature, researchers exploited the fact that complementary DNA bases–the fundamental building blocks of DNA’s double helix–attach to each other. To design the box, the researchers developed a computer program to generate a continuous single-stranded DNA sequence that, along with smaller DNA fragments that act as staples, would self-assemble into the desired shape. The sequence was devised with many complementary regions so that it would automatically fold into six roughly square accordion-like sheets–the sides of the box–based on DNA’s natural tendency to pair into double strands. The DNA staples, also driven by the pairing of complementary sequences, stitched the sheets’ edges together to form a hollow cube with a hinged lid [Technology Review]. The final product was a box that measured 42 by 36 by 36 nanometers, and had a cavity big enough to hold enzymes or virus particles.
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A new genetically modified (GM) corn that produces beta carotene and precursors of vitamin C and folic acid is the first crop to be engineered to make more than one vitamin. Says lead researcher Paul Christou: “The major message of the paper is that it’s possible to engineer crops with multiple nutrients…. If you look at other nutritionally enhanced GM crops, up until now people have only been able to increase levels of one nutrient or vitamin” [Wired]. But anti-GM campaigners have not been won over by the scientific feat, even though the research behind it was not funded by agricultural corporations.
The researchers inserted five genes from other organisms—including rice and Escherichia coli—into a popular South African white corn variety called M37W that Christou said is “completely devoid of vitamins” [Los Angeles Times]. They then bombarded the corn embryos with metal particles coated with chunks of DNA that, if taken up by the embryo, would alter its internal biochemical processes to make it produce the vitamins [BBC]. Follow-up analysis of plants grown from the modified seeds showed not only their successful manipulation, but that the changes lasted several generations. The changes amounted to a 169-fold increase in beta carotene, a precursor of vitamin A. The corn also has six times the normal amount of vitamin C and double the usual level of folate [Los Angeles Times].
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In another sign of Europe’s resistance to the genetically modified crops that have been widely accepted in the United States, Germany outlawed the cultivation of a genetically modified strain of corn produced by the U.S. company Monsanto. Germany joins five other countries — France, Austria, Greece, Hungary and Luxembourg — that have banned the pest-resistant maize despite its approval under a legally-binding EU directive [Nature News].
The strain of corn, known as Mon810, is the only transgenic crop approved in the European Union. Kari Matalone, a spokeswoman for Monsanto, said the corn — which is engineered to resist pests — had been approved for cultivation in Europe more than a decade ago and that no ill effects had been detected since then. “We don’t really understand where this decision is coming from,” Ms. Matalone said [The New York Times]. Monsanto also said it’s considering legal action against Germany.
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The latest advance in battery technology comes from viruses working on the nanoscale. Researchers have constructed a lithium-ion battery, similar to those used in millions of devices, but one which uses genetically engineered viruses to create the negatively charged anode and positively charged cathode [BBC News]. The tiny workers are bacteriophages, viruses that infect bacteria but are harmless to humans.
Three years ago, the same researchers created viruses that collected negatively charged particles of cobalt oxide and gold, which “grew” on a film to create the anode. Now, the researchers have added to that achievement, tackling the trickier task of making cathodes. The work was more difficult because the material had to be highly conductive in order to be effective and most candidate materials for cathodes are highly insulating [BBC News]. The researchers engineered viruses that coat themselves with iron phosphate. Then they then latch onto carbon nanotubes to create a network of highly conductive material [ComputerWorld]. Iron phosphate is generally not a good conductor, but its properties change when it’s organized on the nanoscale.
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In an important step towards creating synthetic life forms, genetics pioneer George Church has produced a man-made version of the part of the cell that turns out proteins, which carry out the business of life. “If you going to make synthetic life that is anything like current life … you have got to have this … biological machine,” Church told reporters in a telephone briefing. And it can have important industrial uses, especially for manufacturing drugs and proteins not found in nature [Reuters].
Church’s team built a functional ribosome from scratch, molecule by molecule. Ribosomes are molecular machines that read strands of RNA and translate the genetic code into proteins. They are exquisitely complex, and previous attempts to reconstitute a ribosome from its constituent parts – dozens of proteins along with several molecules of RNA – yielded poorly functional ribosomes, and even then succeeded only when researchers resorted to “strange conditions” that did not recapitulate the environment of a living cell, Church said [Nature blog]. Next, the researchers want to produce man-made ribosomes that can replicate themselves.
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Researchers have tweaked HIV virus to create a strain that can infect monkeys, and say the development will allow better testing of vaccines and AIDS drugs. Until now, AIDS researchers used monkeys infected with simian immunodeficiency virus, or SIV. The virus is similar to ours, but it’s far from a perfect research tool…. Though SIV and HIV wreak similar havoc on their hosts’ immune systems, drugs affect them differently. While that makes SIV useful for studying how the disease progresses, it’s less useful for studying potential treatments [Wired News].
The new strain of HIV was developed by altering a single gene in the human version to allow it to infect a type of monkey called a pig-tailed macaque [Reuters]. The researchers replaced one HIV gene with the SIV version of the gene, which blocks virus-killing proteins made by the monkey and allows the infection to take hold. Even this altered virus doesn’t make the monkeys very sick, but while animal lovers may see that as a benefit, researchers see it as the final hurdle to overcome.
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In an important step towards the creation of artificial life, scientists in Florida announced this week they have created a synthetic form of DNA that, with a catalyst, can replicate itself. The breakthrough moves biochemist Steven A. Benner closer to achieving what he calls “Darwinian evolution in a test tube” [Seed Magazine].
Benner’s artificial genetic system comprises four nucleotides—building blocks of DNA—seen in humans, plus eight extra nucleotides he created by altering the human versions. He got the synthetic DNA to reproduce using the polymerase chain reaction, a common tool of molecular biology whereby an enzyme triggers the duplication of genetic material; natural DNA, in contrast, can replicate on its own. Once the synthetic form can self-replicate, said Benner, “then it’s artificial life” [LiveScience].
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An extinct mountain goat that was once common in the Pyrenees briefly became the first animal to be brought back from extinction, as researchers used frozen DNA to produce a clone. But the newborn kid died within minutes of birth due to breathing difficulties, signaling that the Jurassic Park dream of resurrecting extinct species is still some way off.
The Pyrenean ibex, or bucardo, is a subspecies of the Spanish ibex that is believed to have died out completely in 2000. Before the death of the last known individual (a 13-year-old female known as Celia), biologists captured her and took cells from her skin and ears, which were frozen in liquid nitrogen. An earlier cloning attempt using the skin cells failed during gestation. But the latest attempt involved the creation of 439 ibex-goat hybrid cloned embryos made by inserting the cell nuclei of the ibex’s skin cells into the egg cells of domestic goats which had their own cell nuclei removed. Of these cloned embryos, 57 were transferred into surrogate mothers and seven resulted in pregnancies, but only one goat gave birth and the newborn clone died after seven minutes as a result of lung deformities [The Independent].
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A Florida couple has just received a genetic copy of their beloved and deceased golden Labrador Sir Lancelot, naming the three-month-old puppy Lancelot Encore. The couple paid $155,000 for one of the first commercially cloned dogs in the world, and say the money was well spent. “He was a wonderful dog,” said Nina Otto, 66. “Money wasn’t an object. We just wanted our wonderful, loving dog back” [ABC News]. The project was masterminded by the California biotech company BioArts.
Lancelot Encore joins a handful of other dogs cloned either commercially or as a proof of concept, and the latest success seems to indicate that researchers have thoroughly overcome the scientific barriers to cloning man’s best friend. Canines are considered one of the more difficult mammals to clone because of their reproductive cycle that includes difficult-to-predict ovulations [Reuters]. Now the fate of the fledging pet cloning industry is largely dependent on whether dog lovers think that clones are worth the high price tag. However, just yesterday another cloning company announced a new technique that could reduce the cost of dog cloning to about $50,000 within three years.
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A tiny worm has developed a compelling system for survival: It avoids trouble and sickness. A single genetic change in the tiny worm Caenorhabditis elegans compels some worms to stay away from harmful bacteria and others to eat the microorganisms [Science News]. While some researchers believe that the healthier worms also have some innate immunity to the bacteria, a new study shows definitively that a gene controls their behavior and keeps them from ingesting substances that will do them harm.
As reported in Science [subscription required], researchers first noted that a Hawaiian population of C. elegans had less resistance to harmful bacteria than the standard laboratory worms. A genetic study revealed that the Hawaiian worms have a different version of a gene called npr-1, which causes them to produce less of a protein that senses signals from neurons. When researchers tweaked the standard lab worms to have the same npr-1 mutation, those worms were also more susceptible to infection, indicating that the single gene was somehow responsible.
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Domesticated pigs got their stripes and spots and other distinctive markings thanks to deliberate breeding efforts by the earliest farmers over the course of thousands of years, according to a new study of pig genetics. While there’s no clear evidence of what motivated those early farmers to change their pigs’ coats, study coauthor Greger Larson says a number of possible reasons present themselves. “One is that it facilitated animal husbandry since it is easier to keep track of livestock that are not camouflaged. Another could be that it has acted as a metaphor for the improved characteristics of the early forms of livestock compared with their wild ancestors.” But another possibility, Larson said, “is that the early farmers were as amused and as taken with biological novelty and diversity as we are today” [HealthDay News].
Novelty may have been the desired characteristic in the first agricultural settlements, but in the wild opposite forces were at work to produce pigs with a consistent brown-black color that served as camouflage. “Every time a gene mutation arose in the wild causing coat colour to change, it was eliminated immediately,” says Greger Larson…. “So if a black piglet showed up, that was the one picked off by a predator” [New Scientist].
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The ravages of global warming could be mitigated by convincing farmers around the world to plant slightly different varieties of corn, barley, and millet, according to a new study which examines the reflective properties of crop plants.Plants reflects short wave energy back out to space much like snow and other light surfaces do. This is known as the albedo effect and is a key component of calculating the effects of climate change. As Arctic ice melts and is replaced by dark water, for instance, the region’s warming is expected to accelerate. Plants have higher or lower reflectivity depending on things like the shape and size of their leaves and how waxy they are [New Scientist].
Lead researcher Andy Ridgwell and his colleagues were inspired in their work by the growing talk of geoengineering fixes for global warming, including ambitious and large-scale projects like seeding the Southern Ocean with iron to encourage algae blooms or building a huge sunshade in the Earth’s orbit. The researchers say their proposal, which they call bio-geoengineering, is more realistic because it uses existing infrastructure. “Arable agriculture is already a global-scale undertaking,” Dr. Ridgwell said. “We wondered whether you might grow slightly different crops and have some sort of climate impact.” … [I]t wouldn’t cost much, and it wouldn’t require much international cooperation. “It’s very practical, and it could just be done,” he said. “It’s not some trillion-dollar pie-in-the-sky idea” [The New York Times].
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A certain herd of 200 goats on a Massachusetts farm may look bucolic and quaint, but they actually comprise a living, breathing pharmaceutical factory, or “pharm.” The goats have been genetically engineered t0 produce a blood-thinning drug in their milk, and a report from the FDA has just declared that the drug is effective and safe for human use. An FDA advisory panel will make a recommendation this Friday on whether to approve the drug for sales; if the drug is approved, it would be the first application under new FDA regulations that allow animals to be genetically altered to produce drugs, model human disease, produce industrial or consumer products or improve their use as food [USA Today].
The goats, which are being bred by the biotech company GTC Biotherapeutics, produce a protein called antithrombin that prevents blood clotting. About 1 in 5,000 people don’t produce enough of the protein, putting them at risk of developing blood clots in their veins. Such clots can be extremely painful. If they break loose and travel through the bloodstream to the lungs or the brain, the consequences can be catastrophic. Pregnant women with the disorder are at high risk of miscarriage or stillbirth, because of blood clots in the placenta [AP]. While people with the deficiency typically manage their condition with conventional blood thinning drugs, such drugs aren’t suitable for surgeries and childbirth, when the risks of blood clots are particularly high–that’s where the new drug would come in. GTC is also developing further studies to test the drug in patients at risk for clots in non-hereditary conditions such as coronary bypass surgery [Reuters].
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The Vatican has issued new ethical guidelines in response to the biomedical advances of the last 20 years, and has come down hard on assisted reproduction technologies and genetic engineering. The document, Dignitas Personae (which translates as “human dignity”), reaffirm the church’s opposition to in vitro fertilization. It also tells Catholics that the church also doesn’t condone “adopting” leftover fertilized embryos from fertility clinics, and frowns upon the genetic testing of embryos before implantation, which could lead to the embryo being discarded. The Vatican says these techniques violate the principles that every human life — even an embryo — is sacred, and that babies should be conceived only through intercourse by a married couple [The New York Times].
These instructions stem from two fundamental theological principles: that life begins at conception and that the origin of human life is the “fruit of marriage.” … The document now makes clear that the morning-after pill, RU-486, and intrauterine devices (IUDs), which either intercept the embryo before implantation or eliminate it after implantation, “fall within the sin of abortion” [Scientific American]. The guidelines may come as a surprise to many Catholics who don’t realize that the church takes such a strict stance on medical technologies like in vitro fertilization that are often seen as routine and beneficial.
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Genetically engineered bacteria can now produce long-chain alcohols that could be used as biofuel, scientists report in the Proceedings of the National Academy of Sciences [subscription required]. Remarkably, the researchers synthetically modified the bacteria’s metabolism to churn out a type of energy-rich alcohol not normally found in nature. “Previous metabolic engineering work typically produces compounds that already exist in nature,” says coauthor James Liao… “Our work here aims to produce compounds that are not synthesized in nature” [Science News].
In addition to ordinary genetic engineering, which involves taking genes from different species (in this case, genes from yeast and a cheese-making bacteria), the new study also required a third, custom-made artificial gene. The three genes were inserted into the genome of E. coli bacteria. The researchers designed the genes to extend E. coli‘s metabolic pathway so that toward the end, the precursor compounds that would normally get converted into amino acids instead turn into long-chain alcohols [Technology Review]. These long-chain alcohols string together six carbon atoms, packing in more potential energy per molecule. Ethanol has only two carbon atoms, and no other naturally-occurring alcohol contains more than five.
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