The Earliest Touchdown

Three hundred million years ago, a flying insect skidded to a landing on a muddy patch of earth and preserved a 3.5-centimeter-long imprint for eternity. From the position of the legs, the curve of the abdomen, and the lack of wing marks, the researchers suspect that the imprint was made by an ancient mayfly that held its wings upright when at rest. Collected in southeastern Massachusetts, the fossil is the oldest known full-body impression of a flying insect, the team reports online today in the Proceedings of National Academy of Sciences. The ability of today’s insects to skim the surface of water is thought to be a modern invention. But the discovery of tiny drag marks (see inset) that suggest that mayflies likely slide before stopping is at least enough to prompt some paleontologists to keep an open mind on the matter.

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Loosing the Louse on Europe’s Largest Invasive Pest


Don’t be duped by its delicate pale flowers; Japanese knotweed can be a sinister plant. Native to eastern Asia, Fallopia japonica was intentionally introduced into gardens in Europe 200 years ago by fans of its attractive blooms; from there it spread to North America. What makes this invasive weed so menacing is its ability to grow through solid concrete foundations, forcing contractors to abandon infested building sites. In England alone, about a half-million homes are uninsurable, and in the United Kingdom, damages and removal cost $288 million a year.

Now the British government has taken a bold step to solve this knotty problem, and North American researchers might not be far behind. Last week, after more than 5 years of research into the matter and an initial pilot trial, the United Kingdom approved the widespread release of one of the plant’s natural enemies. While there are dozens of biological controls already in use against insect pests, this is the fi rst offi cially sanctioned release of one against a weed in the European Union. “This is an extremely important step. … If this is successful, it will really open the doors and open the minds of people for this control method in Europe,” says weed biocontrol specialist Hariet Hinz of CABI Europe in Delemont, Switzerland, a nonprofi t agricultural research organization.

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Researchers Grow Protoeye in Dish

It’s not quite Avatar, but a movie released today shows, in three dimensions, how a chaotic patch of cells grows into the beginnings of an eyeball. Even more impressive, this protoeye was grown in a laboratory dish. Scientists say the finding brings them closer to growing entire organs in the lab, including eyes that could replace those damaged by injury or disease.

In the past decade, researchers have made dramatic progress in understanding how eyes form. They have learned how to turn on and off essential genes and how to transform embryonic stem cells into retinal cells, which can be transplanted into mice to restore vision. But so far, growing an entire eyeball in the lab has eluded scientists, largely because they’ve been unable to recreate the “optic cup,” a chalice-shaped structure that becomes the back of the eye.

Now Yoshiki Sasai of the RIKEN Center for Developmental Biology in Kobe, Japan, and his colleagues have induced embryonic mouse stem cells to spontaneously form the optic cup in a dish. The key ingredient was a mixture of jellylike proteins, called Matrigel, which forms an enticing bed on which stem cells seem to prefer to lie before turning into the eye’s various structures.

In the movie, the cells—made to glow green—push out before inverting and forming two different layers: the first, the retinal cells, and the second, the neurons. This is the first demonstration that stem cells direct their own development in the eye, the team reports online today in Nature.

Knowing that stem cells can direct their own development is key if we want to grow organs without having to also grow the tissues that usually develop around them, says developmental biologist Jane Sowden of University College London, who was not involved in the study. She says that even though Sasai’s team hasn’t yet grown an entire eyeball in a dish, the work shows that it’s possible to grow specific eye structures, such as retinas, from stem cells in a great enough quantity that they could be used in therapy. If the researchers can get the technique to work with human stem cells, she says, it could help the one in 3000 people born with a form of blindness caused by damaged retinal cells and the many more who lose their sight because of age-related disease.

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Now That’s a Big Number

Worried about having enough hard drive space to store all of your holiday pictures? Just be glad you don’t have to cope with the 9.57 zettabytes—that’s 9,570,000,000,000,000,000,000 bytes—of information that the world’s 27 million business computer servers process each year. If you divided 9.57 zettabytes among the 3.18 billion workers that make up today’s global labor force, then each person would receive around 3 terabytes of information per year. That’s enough to fill the largest external hard drive three times over. What’s most worrying is that this number will likely double every 2 years, according to researchers who presented their estimates at a conference for data storage professionals in the United States in Santa Clara, California, today. Might be time for a reformat.

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Sensing Organ Rejection


Rejection hurts, but for organ transplant patients it’s more than an emotive issue—it can be a matter of life and death. Having waited months, sometimes years, for a donor and survived major surgery, transplant patients face an uphill battle to prevent their immune systems from rejecting their new organ. Now a new test in which a transplant patient’s blood is scanned for DNA from the donor organ can alert doctors if serious rejection has begun, allowing them to try to stop the process.

Approximately 40% of transplant patients experience at least one episode of acute rejection in the first year after they receive an organ. Catching any major immunological backlash early is key to minimizing its effects, especially because most rejection episodes are reversible with a large dose of immunosuppressant drugs. But patients typically must undergo regular biopsies of their new organ to monitor its health; the procedure is both painful and expensive, and biopsies also risk damaging the organ, explains cardiologist Hannah Valantine of Stanford University School of Medicine in Palo Alto, California. In 2009, Valantine developed a noninvasive rejection test that relies on monitoring a patient’s immune system. AlloMap became the first U.S Food and Drug Administration-approved test for heart transplants, but it still fails to catch about half of rejection events.

To capture the rest, Valantine recently headed back to the drawing board. This time she enlisted help from biophysicist Stephen Quake of Stanford. Together they designed a test that relies on the fact that a transplanted organ’s genome is distinct from that of its new host. The test monitors fragments of DNA released by the organ into the blood, when cells from the transplant tissue are naturally broken down. To validate this strategy, the researchers tried their test on stored blood plasma from organ transplant patients, some of whom had had confirmed rejection episodes. During a rejection event, the levels of circulating DNA from the donor organ go up, making up on average 3% of free DNA in the recipient’s blood rather than the typical 1%, the researchers report online today in the Proceedings of National Academy of Sciences.

Valantine hopes that this test can eliminate the need for regular biopsies as a means of rejection monitoring; patients often have one every month in the first year after a transplant. Instead, physicians would perform confirmation biopsies only if the DNA test results were positive. The new test can detect “very low levels of DNA to predict rejection,” Valantine says, making this approach more sensitive than the AlloMap test. If the test can alert doctors to rejection earlier, she notes, they can “tinker” with the levels of immunosuppressant drugs rather than go in with “a big-gun approach” that lowers the patient’s immune system so much that they are at risk of infection and cancer.

Bruce Rosengard, the surgical director of the cardiac transplantation program at Massachusetts General Hospital in Boston, is cautiously optimistic about the new test. “Organ rejection remains one of the primary obstacles to transplant success,” he says. “Anything that we can do to reduce the number of heart biopsies is a very positive development. … I think this approach will gain traction pretty quickly.”

Valantine hopes to have the new test available to doctors in a year’s time, adding that she sees no reason why it can’t be used to detect rejection of other transplanted organs.

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Monkeys Chew the Cud

Eating your greens can be grueling, especially if you are a monkey who dines on a high fiber diet. Some primates overcome their digestive dilemma by hosting microbes in their guts that help them breakdown the tougher leaves, much like cows do. Cows and other ruminants also maximize this symbiotic relationship by regurgitating and rechewing their stomach contents to get the most out of each meal. This behavior was considered unique to four-legged herbivores. Now researchers have witnessed proboscis monkeys that live in the mangroves and swamps of Borneo doing the same (see the video). This is the first evidence that primates ruminate, too, reports the team online today in Biology Letters, and gives us all something to chew over.

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The Oldest Buttercup Yet

Darwin called the origin of flowering plants an “abominable mystery.” They appear in the fossil record and immediately grow abundant and varied, creating a problem for his theory of slow but continuous change. The unearthing of a new fossil in northeast China, described online today in Nature, could explain the apparent contradiction. The ancient flowering plant, Archaefructus liaoningensis, resembles a modern-day buttercup, with slender stems and three-lobed leaves. Its discovery pushes back the date of when flowering plants diversified to around 127 million years ago, during the early Cretaceous period. That’s a couple of million years earlier than Darwin had previously thought, suggesting that these ancient blooms had longer to evolve than he suspected.

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Beyond Entropy

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Nosing Out a Smell Gene

The daily smells of the world—the freshness of spring flowers, the smokiness of charred morning toast, the invigorating aroma of a cup of coffee—are lost on those with anosmia, a complete inability to detect odors. Now, thanks to a trio of people who feel no pain, a new study has pinpointed the first set of mutations that are to blame for this condition. The finding could help scientists better understand the gradual loss of smell that happens with age.

The discovery was somewhat happenchance. It began when neurobiologist Frank Zufall of Saarland University in Homburg, Germany, was contacted by pain researcher John Wood of University College London and geneticist Geoffrey Woods of the University of Cambridge in the United Kingdom. Wood and Woods had been studying three people with an inability to feel pain. In 2006, they found that all had mutations in a gene that codes for a sodium channel called Nav1.7 that is involved in the firing of neurons. The researchers also noticed that the volunteers reported having no sense of smell. When the duo created mice with similar mutations, the pups were free of pain, but they also had difficulty smelling; they seemed unable to pick up the odor of their mother’s teats to suckle, for example.

To investigate how the lack of these channels causes anosmia, Zufall and his team studied the genetically engineered mice. They discovered that although neurons in the rodents’ noses respond to different odors, they were unable to transmit these signals to the olfactory bulb, the region at the front of the brain that processes smell.

The researchers also confirmed that the mice couldn’t smell. In a series of experiments, the rodents didn’t avoid the smell of predators, nor did they retrieve their pups when they were scattered around their cage, the researchers report online today in Nature. “This behavior supports that fact that the mice aren’t smelling,” says Lisa Stowers, a neurobiologist at The Scripps Research Institute in San Diego, California, who studies olfaction.

Zufall hopes to turn up more genes underlying anosmia by encouraging doctors to carry out a smell test in patients who present with neurological problems. Peter Mombaerts, an olfaction neuroscientist at the Max Planck Institute of Biophysics in Frankfurt, Germany, agrees that this would be a good approach. “It is a very cheap test,” he says, but he cautions that few doctors currently do it, even though smell can be an important indicator of neurological disease. For example, in Alzheimer’s patients, smell is often one of the first things to deteriorate.

The number of people that are anosmic from birth is likely quite small, says Mombaerts, but by better understanding how olfactory signals are disrupted in people born with this condition, researchers hope to gain insight into why many more develop it later in life.

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