It was only a few years ago that scientists figured out how to reprogram adult cells to make them act like multipurpose stem cells, but the next discoveries are coming fast and furious. Researchers had previously transformed human skin cells into so-called induced pluripotent stem (iPS) cells that can grow into any type of tissue; now, a new study reports that the same feat has been accomplished with pig cells. The achievement raises the possibility that genetically engineered pigs could be reared as organ donors, researchers say.
The created iPS cells could be genetically altered, and then cloned to produce pigs with certain traits. By adding or deleting certain genes, for example, researchers could produce pigs whose organs can be transplanted into patients without them being recognised and rejected. Efforts to do such xenotransplants have already been under way for at least a decade, but iPS cells are easier to genetically engineer and grow in the lab than pig embryos, opening up new possibilities for xenotransplantation [New Scientist]. Pigs are considered potential organ donors because their organs are already similar to those of humans in size and function.
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Scientists have taken another step in cellular reprogramming that points the way towards the use of a patient’s own cells to treat genetic diseases. In a proof of concept study, researchers took skin cells from patients with a rare condition, Fanconi anemia, which causes skeletal problems and bone-marrow failure, and raises sufferers’ risk of cancer [Technology Review]. In the skin cells, the researchers fixed the genetic defects that caused the disease, and then reprogrammed the cells to act like stem cells capable of growing into any type of tissue.
The corrected stem cells could be grown into blood precursor cells for therapy. As these would carry a patient’s own DNA, except for the mutation responsible for the illness, they could be transplanted without risk of rejection by the body’s immune system [Times Online]. However, the patched up cells were not used to treat patients in this study, because it isn’t yet clear whether such cells are safe. Comments molecular geneticist Chris Mathew: “In future it may become possible to transfer the corrected stem cells back into the patient, but much work remains to be done before this can be transferred from the lab bench to the bedside” [The Scientist].
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Researchers have endowed lab mice with the human version of a gene involved in language, and while the mice didn’t exactly sit up and start reciting poetry about cheese, they did show some intriguing differences in both their vocal patterns and brain structure.
Mice have their own form of the gene, called FOXP2, but they and all other animals lack key changes found only in humans and our evolutionary cousins, Neanderthals. Some researchers speculate that these differences may help explain why humans are the only animal able to communicate with complex languages, and not simple grunts, barks or songs [New Scientist]. By tweaking the gene in mice and changing it to the human form, researchers hoped to get a clue as to how our early hominid ancestors were changed by the new form of the gene.
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Researchers have found a new way to reprogram human skin cells to act like multipurpose stem cells, and say their safe technique produces stem cells that are ready for medical use. If the researchers are right, clinical trials on the induced pluripotent stem (iPS) cells, which can turn into virtually any cell type and potentially be used to treat disorders ranging from spinal cord injury to diabetes, could start within two years [Nature News].
Many experts say that reprogrammed skin cells have several advantages over embryonic stem cells, for reasons both societal and medical. Using adult cells dodges the ethical controversy involved in taking cells from embryos, and it also raises the possibility that patients’ own cells could be used in their medical treatment, negating the chance that the cells would be rejected by their bodies. But reprogramming cells is still a scientific frontier, and researchers have struggled to find safe ways to accomplish the feat.
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Five small monkeys that glow green under ultraviolet light are providing a beacon for medical research. Researchers introduced a jellyfish gene that codes for a fluorescent protein into the embryos of marmosets, and found that the resulting monkeys expressed the gene in all the cells of their body, including their egg and sperm cells–which means the genetically engineered primates can naturally pass on the foreign trait to their offspring. While creating a family of glowing monkeys doesn’t have obvious benefits for medical science, researchers say the study was really just a proof of concept.
Researchers have added genes to rhesus macaques before, but the new work with marmosets is the first to document that monkeys can pass an inserted gene along to future generations. That’s important because it opens the door to creating colonies of such “transgenic” monkeys by breeding, which would be far simpler than the cumbersome process of making each animal from scratch by inserting genes into embryos [AP]. Now that researchers have mastered the technique, they hope to create transgenic monkeys that carry genes associated with such diseases as Parkinson’s and Lou Gehrig’s disease.
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All’s fair in the fight against the AIDS virus–including medical sneak attacks. Researchers have devised a novel strategy to attack HIV by completely bypassing the immune system and instead tricking the muscles into producing virus-fighting proteins.
The quest for an HIV vaccine has been given a bad prognosis recently, due to increasing agreement that the human immune system isn’t clever enough to outsmart the ever-changing surface of the virus [Technology Review]. But using the new technique, researchers were able to protect monkeys from infection by the simian immunodeficiency virus (SIV), the animal virus most closely related to HIV. While lead researcher Philip Johnson cautions that there’s no guarantee that the vaccination process will work in humans, he’s eagerly looking forward to human trials in a few years.
Most efforts at blocking AIDS have sought to stimulate the body’s immune system to produce antibodies that fight the disease. This model has worked for diseases such as measles and smallpox. It hasn’t done as well with HIV/AIDS; test vaccines have failed to produce a protective reaction. So Johnson decided to try something different. “We used a leapfrog strategy, bypassing the natural immune system response that was the target of all previous HIV and SIV vaccine candidates,” Johnson said [AP].
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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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