News this Week

Science  27 Aug 2010:
Vol. 329, Issue 5995, pp. 1000
  1. Chronic Fatigue Syndrome

    New XMRV Paper Looks Good, Skeptics Admit—Yet Doubts Linger

    1. Martin Enserink

    The plot thickens. This week, a long-awaited paper by U.S. government labs about the link between a virus and chronic fatigue syndrome (CFS) finally saw the light of day. The study confirms a controversial 2009 paper that reported CFS patients are often infected with the virus, called XMRV. Since then, four other studies have failed to duplicate those findings. Even skeptics are impressed by how much care the authors of the new study took to ensure accuracy. But that makes it even more baffling why some labs easily detect the virus while others can't find a trace of it in any patient.

    The new paper, published on Monday by the Proceedings of the National Academy of Sciences (PNAS), also adds a confusing twist: Rather than XMRV itself, the team found a broader and more diverse group of closely related viruses. That leads some critics to say the paper is a new finding, not confirmation of the first one. “Let's be clear. This is another virus,” says retrovirologist Myra McClure of Imperial College London, a co-author of one of the four negative studies.

    The controversy began in October 2009, when a team led by Judy Mikovits of the Whittemore Peterson Institute (WPI) in Reno, Nevada, reported in Science (23 October 2009, p. 585) that 67% of CFS patients were infected with XMRV, compared to just 3.4% of healthy controls. The study caused huge excitement among patients and raised hopes of a cure. But when four other groups were unable to repeat the results, some suspected that WPI, a privately funded lab many researchers had never even heard of, might be wrong.

    U.S. government labs soon found themselves on opposite sides of the debate. Researchers at the Centers for Disease Control and Prevention (CDC) failed to find the virus, whereas the new study—by scientists at the Food and Drug Administration (FDA), the National Institutes of Health (NIH), and Harvard Medical School—says that Mikovits was right. Both groups temporarily put their papers on hold to check their results and try to understand what was going on (Science, 2 July, p. 18). Both eventually felt confident enough to publish, and the negative CDC paper appeared in Retrovirology in July.

    No doubt.

    NIH's Harvey Alter says he's sure the findings are not the result of mistakes or contamination.

    CREDIT: NIH

    For the PNAS paper, researchers looked for traces of XMRV's so-called gag gene in samples taken from 37 CFS patients collected in the mid-1990s. They found evidence for the virus in 32 (87%) of the patients, but in only 3 out of 44 healthy controls (6.8%). The group went to great lengths to avoid errors, says senior author Harvey Alter of the NIH Clinical Center. XMRV is closely related to an endogenous mouse retrovirus, so the team tested every sample positive for XMRV for traces of mouse mitochondrial DNA, which would have been a telltale sign of lab contamination. They found none. They also took fresh samples from eight of the patients and found that, 15 years on, they were still infected, and that the virus had evolved, “just as we would expect from a retrovirus,” says Alter.

    The data do seem solid, admits Steve Monroe, director of CDC's Division of High-Consequence Pathogens and Pathology. “It's simply a good paper,” adds virologist Reinhard Kurth, former director of the Robert Koch Institute in Berlin. Alter, a widely respected virologist and winner of the Albert Lasker Award for Clinical Medical Research, “clearly knows what he is doing.” But Kurth nonetheless remains skeptical. So does Robin Weiss of Imperial College London, who says he's seen too many instances of proposed new human retroviruses that fell apart on closer inspection—including one he reported in 1999. “You can have a very good reputation and be very careful, and still get it wrong,” Weiss says.

    Part of the problem, skeptics say, is that the researchers didn't exactly replicate the Science paper. XMRV is a so-called xenotropic murine virus, which means it can no longer enter mouse cells but can infect cells of other species. The PNAS authors say the viral sequences they find are quite diverse and more closely resemble the so-called polytropic mouse viruses, which is why they adopted the term MLV-related virus, for murine leukemia virus. But Alter says that XMRV is a subset of MLVs, and that his work does support the earlier study. Mikovits—who is “delighted” by the results—says that in the meantime, her group has found more diversity in the virus as well.

    A working group coordinated by the National Heart, Lung, and Blood Institute (NHLBI) is already trying to find out why careful studies by veteran scientists can have such opposing results. Patient selection could play a role: Different studies have used different diagnostic and recruitment criteria. But even so, it's hard to explain why four studies wouldn't have included a single infected patient.

    Subtle differences in sample collection and handling, or in the way tests are performed, could also have led the four labs to miss the virus. But CDC's Monroe says he's confident that his lab can identify XMRV correctly. As part of the NHLBI program, researchers at FDA, CDC, WPI, and other labs have all blindly tested a panel of samples, some of them “spiked” with different amounts of the virus; all of them performed well. Further exchange of samples and reagents is now under way. “They should be able to clear this up by Christmas,” says Kurth.

  2. Marine Ecology

    Hard Summer for Corals Kindles Fears for Survival of Reefs

    1. Dennis Normile

    Coral reefs are reeling from extensive bleaching in the Indian Ocean and throughout Southeast Asia. “It rivals 1998,” when massive bleaching associated with high ocean temperatures destroyed 16% of the world's coral reefs, says Clive Wilkinson, a coral reef ecologist at Australia's Reef and Rainforest Research Centre in Townsville. And although some hard-hit areas have cooled—offering hope that some reefs may rebound—other regions are just now heating up. Based on current sea surface temperatures, the U.S. National Oceanic and Atmospheric Administration (NOAA) has issued an alert for the Western Pacific and the Caribbean. “We're looking at the potential for very warm temperatures causing significant coral bleaching over the next couple of months,” says C. Mark Eakin, a NOAA coral reef ecologist in charge of the agency's Coral Reef Watch.

    The blight is expected to harm a host of sea creatures. When the “rainforests of the oceans” are degraded or die, a wide variety of marine life that depend on reefs suffer. And humans too feel the pain: Any decrease in fisheries productivity and loss of tourism affects coastal communities.

    Many reefs will be hard pressed to recover from this year's bleaching. According to Eakin, global warming appears to be increasing the frequency of bleaching events. That can spell doom for reefs. “If you get too many repetitive lethal events, the corals will not recover,” Wilkinson says.

    Corals harbor symbiotic algae called zooxanthellae that use photosynthesis to produce nutrients for themselves and their hosts. Sustained above-average water temperatures and intense sunlight can upset the delicate symbiotic balance, prompting corals to expel zooxanthellae. The corals turn white, or bleach. If weather conditions ease quickly enough, the algae repopulate coral. Prolonged bleaching is lethal.

    The most recent massive worldwide bleaching incident occurred in 1998, when El Niño conditions in the South Pacific caused sea surface temperatures to soar across the globe. This year, too, the hand of El Niño was at work. According to Coral Reef Watch, warming started in early summer in the Indian Ocean and persisted until cooling monsoon rains arrived. High temperatures later hit Southeast Asia and the Coral Triangle, which stretches from central Indonesia east to the Solomon Islands and north through the Philippines. In recent weeks, sea surface temperatures have risen in the Western Pacific in a band from Micronesia to Guam and the Northern Mariana Islands, and in the southern Caribbean. In some areas, says Eakin, temperatures “are worse than in '98.”

    Scientists are still surveying the damage. Early data are grim. Reefs on both sides of the Thai Peninsula were hit, with up to 100% of some coral species bleached, says James True, a coral biologist at Prince of Songkla University in Hat Yai, Thailand. He expects at least 80% of the most sensitive species to die. “A few inshore reefs got so badly damaged they probably won't ever come back to the way they were,” he says. Among surviving corals, “disease is rampant,” True says, with two to three times the usual incidence of necrotic lesions and growth anomalies. Similar reports of “quite extensive bleaching” have come from Vietnam and through the heart of the Coral Triangle in Indonesia and the Philippines, says Wilkinson, who coordinates the Global Coral Reef Monitoring Network, which tracks reef status and promotes conservation.

    Whiter shade of pale.

    A bleached coral on a Thai reef will likely crumble and litter the sea floor.

    CREDIT: JAMES GUEST

    Some ailing reefs had just begun to recover from the 1998 bleaching. “We've got examples of reefs that were bouncing back quite rapidly 10 years after a 90% die off,” Wilkinson says. But they were still at least a decade away from full health, and it would take decades longer for slower growing corals to recover. Eakin says that is a particular worry in the Caribbean, where localized bleaching caused extensive coral death 5 years ago and reefs have yet to bounce back.

    This year's bleaching event has some disturbing new wrinkles. In some regions, it seems to be hammering normally resistant species while sparing Acropora, a fast-growing coral that is usually the first to succumb. “We don't know why, but it's tempting to suggest it is adaptation,” says James Guest, a marine biologist at the National University of Singapore. Acropora that survived in 1998 and repopulated reefs may have had some resistance to bleaching, he says, or perhaps they have taken in zooxanthellae that are less sensitive to higher temperatures. Even if further studies demonstrate some degree of adaptation among corals, Guest warns that future reefs will look quite different from those of today.

    Researchers can only watch as the nightmare unfolds. While bleaching is occurring, “there's literally nothing you can do,” Wilkinson says. Reefs that were recovering from the 1998 event were far from inhabited coasts or managed in a way to minimize stress from damaging fishing practices and sedimentation from runoff. This year, much of the bleaching is occurring on reefs already under siege.

    The long-term prognosis is bleak. Global warming is pushing baseline sea temperatures upward, says Eakin, causing localized bleaching even in years without an El Niño. “Unless there is concerted action to reduce greenhouse gases,” he warns, “bleaching will become increasingly common and not just during extraordinary weather events.”

  3. China

    Astronomers Hope Their Prize Telescope Isn't Blinded by the Light

    1. Richard Stone
    LAMOST lite?

    Rising light pollution may undermine LAMOST's ambitious science program.

    CREDIT: R. STONE/SCIENCE

    BEIJING—Chinese astronomers thought they had their hands full, fine-tuning their complicated new survey telescope into next year. Now they have a more urgent problem: Light pollution could jeopardize its ambitious science program.

    Concerns are growing over light from a planned astronomy education center to be built near the $40 million Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) in Xinglong, 170 kilometers northeast of Beijing. “The local sky is already bright. Even a little more light will ruin the project,” warns Deng Licai, an astronomer with the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) here who is rallying opposition to the center. If authorities follow through with their plan to put the center just south of LAMOST, Deng says, “I will do anything to stop it.”

    Senior NAOC officials are aware of the threat. The education center, they say, would reduce light pollution because it could dampen light from dwellings—villagers will be relocated—and astronomers will regulate the center's operations and lighting. Villagers may also learn to value a dark sky and voluntarily reduce light emissions. “We want a win-win solution,” says senior engineer Liu Xiaoqun, an NAOC deputy director-general. NAOC is also helping draft a national regulation that would curtail light pollution in the vicinity of observatories across the country.

    For China's astronomy community, the stakes are high. “This is the most important instrument of our generation,” says Deng. LAMOST, now also called the Guoshoujing Telescope, after a Ming Dynasty astronomer, should be able to peer twice as deep into space and time as its predecessor, the Sloan Digital Sky Survey. Astronomers plan to acquire spectra from 14 million celestial sources to shed light on the structure of the universe and on a long-standing puzzle: how galaxies form (Science, 4 April 2008, p. 34).

    Astronomers realized China's growth would bring increasing light pollution. For LAMOST, the main culprits are Beijing and the telescope's home in Xinglong, a county of 50,000. “But it's worse than we expected,” Deng says. For months, NAOC leaders have been discussing with local officials how to safeguard observing conditions. In response, the Xinglong government has closed 18 factories, removed 50 dust-spewing boilers and furnaces, shuttered five searchlights, and fit more than 200 streetlights with covers, says Liu. Further steps could include replacing incandescent streetlights with low-pressure sodium lamps and turning off some streetlights after most people go to sleep, says Jiang Xiaojun, chief engineer of Xinglong Station. However, he warns, “if light pollution around the observatory is uncontrolled and keeps increasing, the observatory will have to be closed down or moved away.”

    The education center is a new source of angst. In 2007, the governments of Xinglong County and Chengde, a major city with authority over Xinglong, began drafting plans to build the center on the south-facing slope of the hill on which LAMOST is perched. Local authorities see the telescope as a tourist draw that could boost their economy. “Nobody, including us, has the privilege … to impose limits on their development,” Liu says. The challenge is to minimize the impact on the observatory, he says. That could mean, for example, keeping any night activities indoors and behind thick curtains. Another possible remedy is to build the center farther from the observatory, says LAMOST chief engineer Cui Xiangqun of the Nanjing Institute of Astronomical Optics and Technology.

    Some Chinese astronomers chafe at the fact that they were not aware of ongoing discussions about the education center. Deng says he learned about the plan from a news report on the Internet several weeks ago. “I could not believe it,” he says. LAMOST is pointed southward, at a patch of sky near the meridian. Any light from a facility would further brighten LAMOST's viewing area—from 20 degrees north of overhead to 50 degrees south of overhead—“and be extremely harmful to the site,” says Deng. “The closer a light source is to the telescope, the higher in the sky the plume of light is visible,” adds Heidi Newberg, an astronomer at Rensselaer Polytechnic Institute in Troy, New York, and a member of LAMOST's survey planning working group.

    Meanwhile, engineers are racing to commission the complex telescope, which has an innovative active optics system that deforms the correcting mirror's 24 plates individually. At the focal surface, 4000 optical fibers will feed starlight into a battalion of spectrographs. Data gathered in recent weeks have revealed more than a dozen uncharted quasars and scores of planetary nebulae in the Andromeda Galaxy, two teams report in the latest issue of Research in Astronomy and Astrophysics. As promising as the early data are, Deng says, it will take several months to get the telescope performing up to its design specifications. Then the survey proper would get under way.

    “For the sake of astronomical productivity,” says Newberg, “I hope that development in the region can be kept to a minimum, particularly to the south of the telescope, and particularly in the next 5 to 10 years.” Deng, for one, is not optimistic. “Anytime a scientific or environmental project is in conflict with development in China,” he says, “development always wins.” Now, with the education center likely to go ahead, Deng says LAMOST astronomers are even mulling whether to “adjust our science plan to carry out less important research.”

  4. Research Facilities

    U.S. Physicists Eye Australia for New Site of Gravitational-Wave Detector

    1. Adrian Cho

    U.S. physicists hope that the offer is too good for Australia to refuse.

    They want to take parts from their massive twin gravitational-wave detectors and use them to build a third detector near Perth in western Australia. Adding a detector down under would greatly enhance the ability of the Laser Interferometer Gravitational-Wave Observatory (LIGO) to pinpoint sources of gravitational waves, should such waves ever be spotted. The cost to Australia would be $170 million, the price tag for building and maintaining the new site. In return, Australian physicists would gain full participation in the half-billion-dollar experiment.

    “It's absolutely a win-win situation,” says David Blair, a physicist at the University of Western Australia (UWA) in Crawley. But the Australian government must decide in the next year. “We're asking a lot of Australia,” says Stanley Whitcomb, a physicist at the California Institute of Technology (Caltech) in Pasadena and LIGO's chief scientist. “I don't think there's anybody who thinks there's better than a 50-50 chance of this happening.”

    LIGO Executive Director Jay Marx hatched the idea last October after a workshop in Shanghai, China, as a way to greatly enhance LIGO's performance as a gravitational-wave telescope as well as a detector. Built for $294 million by the U.S. National Science Foundation (NSF), LIGO aims to detect tiny ripples in the fabric of space and time set off when, for example, two massive neutron stars spiral into each other. To sense those ripples, LIGO uses huge optical motion sensors called interferometers in Hanford, Washington, and Livingston, Louisiana.

    LIGO already works in concert with a European detector, called VIRGO, in Cascina, Italy, near Pisa. By comparing the times at which the three detectors sense a pulse of gravitational waves, scientists should be able to locate the waves' source to within a couple of degrees in some parts of the sky. But LIGO and VIRGO cannot pin down sources that lie in the plane defined by the locations of the three detectors. Adding a fourth station in Australia would create other planes and enable researchers to locate a source to within a degree or so across the entire sky (see figure.)

    In fact, a third LIGO detector is already running in the background at the Hanford site. Each LIGO station consists of two 4-kilometer-long vacuum chambers arranged in a gigantic L. Light from a high-power laser bounces between the mirrors at either end of each tube, or “arm,” and by comparing the two streams of light scientists can detect changes in the relative lengths of the arms as small as 0.001 times the width of a proton. At Hanford, a second set of mirrors and equipment in the same building forms a 2-kilometer interferometer that serves as a crosscheck for the bigger device.

    But there's now a chance to move that third detector somewhere else, says Albert Lazzarini, a physicist at Caltech and deputy director of LIGO. Two years ago, LIGO scientists began a $205 million upgrade to all the detectors that, when it's completed in 2015, should make them 10 times more sensitive. The original plan for Advanced LIGO was to stretch the smaller Hanford detector to a full-size one at its current site. But it does not have to sit atop the first detector to serve as a cross-check, Lazzarini says.

    Clearly better.

    These sky maps—smaller ellipses denote higher precision—show that the addition of another detector in Australia (top) would greatly improve physicists' ability to pinpoint gravitational-wave sources under the current plan (above). LIGO's Louisiana site is pictured.

    CREDITS (TOP TO BOTTOM): REPORT OF THE COMMITTEE TO COMPARE THE SCIENTIFIC CASES FOR AHLV AND HHLV, R. WEISS ET AL.; (PHOTO) NSF/LIGO

    So in the new scheme, parts for that detector would be shipped to Australia to build a new detector in Gingin, 80 kilometers north of Perth. “We would basically be asking the NSF to deliver one set of hardware to another continent,” Lazzarini says.

    That's a radical change of plans, and it would have to happen fast: Researchers plan to start taking apart the current LIGO detectors in October and installing the new equipment next year. But NSF likes the idea of putting a detector in Australia so much that it's willing to rock the boat, says Beverly Berger, program director for gravitational physics at the agency. “It's project management 101 that you don't change a major project once it's under way unless you've got a compelling reason to do so,” she says. This week, NSF officials pitched the plan to the agency's governing National Science Board.

    NSF officials are not willing to pay more for Advanced LIGO, however, so the burden will fall on the Australian government. Building the site would cost about $125 million, says Robyn Owens, vice president for research at UWA, and running it for 10 years would cost another $45 million. If all goes well, the Australian detector could start taking data in 2017.

    Australian physicists have been trying for decades to persuade their government to build a similar detector. “We really think that this collaboration could make all the difference,” Blair says. Whitcomb notes that Australia has by far the most robust gravitational-wave community in the Southern Hemisphere.

    The road to approval may be tricky, however. It will begin with a proposal to Australia's National Research Infrastructure Committee, but beyond that there is no protocol for getting such an expensive project approved, Owens says. Instead, researchers must simply convince politicians that the idea is worth funding. And that may have just gotten a bit harder. Australia's Labor Party lost its parliamentary majority in national elections last weekend, while the more-conservative Liberal/National coalition, which has promised to cut spending, gained seats. One party or the other will likely form a coalition government.

    Still, Owens and colleagues are hopeful that politicians in both parties will recognize the opportunity. “This project has the ability to capture people's imagination,” she says. Time is short: The Australians have only a year or so to claim their prize before LIGO researchers start installing the hardware at Hanford.

  5. Cell Biology

    To Scientists' Dismay, Mixed-Up Cell Lines Strike Again

    1. Gretchen Vogel

    Call it the case of the cells that grew too much. Over the past 5 years, a handful of research teams have raised concerns about ongoing attempts to transplant mesenchymal stem cells (MSCs), stem cells found in bone marrow and muscle, into people with heart disease and other conditions. The groups had found that MSCs could become cancerlike after growing for months in the lab. But three of these research teams have now discovered that the cancerlike cells they spotted are unrelated to the original MSCs. In each case, tumor cells that the researchers were using for other projects had contaminated the MSCs and, because they grow faster than the stem cells, ultimately took over the cell culture.

    The discovery of these contaminations prompted the retraction this month of one paper and the correction of another. “It's not a good feeling,” says Rolf Bjerkvig, a cell biologist at the University of Bergen in Norway who led one of the teams deceived by stray cancer cells. “First you are in shock. Then you have to cope with it.”

    Suspicious scene.

    Researchers in Norway thought that mesenchymal stem cells (bottom left) in their lab had turned cancerous. Months after publishing a paper, they discovered that the tumor cells (bottom right) were the result of contamination.

    CREDITS (TOP TO BOTTOM): © ISTOCKPHOTO.COM/RON KLOBERDANZ; ANJA TORSVIK AND ANDERS MOLVEN/UNIVERSITY OF BERGEN, NORWAY

    The news has left stem cell scientists uncertain about whether MSC therapy poses a cancer risk. It's also reinvigorated calls for scientists to take safeguards against cell line contamination—an issue that has vexed biologists for decades (Science, 16 February 2007, p. 928)—and for journals to require that cell lines be validated as a condition of publication.

    The problem of misidentified cells, say cell banking experts and researchers who have learned the hard way, has a simple solution: DNA fingerprinting. The same technology that can help solve murder or rape cases can easily and cheaply prevent months or even years of wasted work, says Wilhelm Dirks of the German Collection of Microorganisms and Cell Cultures (DSMZ) in Braunschweig, Germany.

    Yet journals and funding agencies have resisted pleas by many scientists to require DNA fingerprinting of cell lines. Dirks is now part of a panel that is in the final stages of writing standards to guide researchers in using a type of DNA fingerprinting called short tandem repeat (STR) profiling to identify human cell lines. He and his colleagues hope the standards, which were commissioned by the cell repository ATCC in Manassas, Virginia, will raise awareness of cell misidentification and help make it standard practice for labs to check their cell lines regularly for cross-contamination.

    Like many of the previous cases of spurious cells, the new MSC examples involve tumor cells. In 2005, J. García-Castro, now at the Instituto de Salud Carlos III in Madrid, and his colleagues reported in Cancer Research that MSCs growing in their lab spontaneously turned tumorlike. But during several years of attempting to determine what triggered the transformation, the researchers never saw a similar event. Finally, the group used STR analysis to characterize the transformed cells and the MSC. They didn't match. Instead, the transformed cells are very similar to a sarcoma tumor cell line called HT1080, García-Castro and his co-authors reported in May. They retracted the original paper on 15 August.

    Bjerkvig and his colleagues had a remarkably similar experience. Several years ago, they thought they observed the spontaneous transformation of MSCs into cancerlike cells. When Bjerkvig learned that German scientists had seen the same thing in their lab, the two groups cooperated on a paper, published last year in Cancer Research.

    But a few months after the publication, Bjerkvig says, his lab subjected all their cell lines to DNA fingerprinting and found that the transformed cells failed to match the MSCs. Instead, they fit the DNA profile of HT1080 as well as a cell line called U-2 OS. They alerted their German colleagues, whose “transformed” cells turned out to be glioma cell lines called U251 and U373. The teams reported their discovery online 14 July in Cancer Research.

    Bjerkvig and García-Castro now both urge research groups to test their cell lines' identities early and often. Unfortunately, says Dirks, despite 50 years of warnings about cell line contamination, very few groups do so, and the problem is still widespread. For example, he says, there have been more than 1000 papers published using a cell line called ECV304, which was originally thought to be normal endothelial cells that had spontaneously immortalized in lab culture. But in 1999, Dirks and several colleagues showed that the cells were in fact another cell line derived from a human bladder carcinoma. And yet, nearly 80 papers published in 2008 still referred to ECV304 as normal endothelial cells, Dirks and his colleague Roderick MacLeod found.

    They and two dozen colleagues on ATCC's panel hope that their newly developed standards will be “the beginning of the end” of cell line misidentification. The document and an accompanying database will provide validated DNA profiles for known cell lines as well as guidelines for interpreting STR assays. “It should be the bible for DNA fingerprinting,” says Liz Kerrigan of ATCC. The database, hosted by the National Center for Biotechnology Information in Bethesda, Maryland, will also allow scientists to add STR profiles from new lines derived in their labs, Kerrigan says. Expense is no excuse, Dirks says; a full STR analysis costs less than $200. Already, several online databases make it possible for scientists to compare the DNA fingerprints of cells in their labs with those of cell lines in cell banks around the world. Dirks says use of DSMZ's database has been growing steadily since it went online last year.

    As for scientists using MSCs, the question of whether transplants of the cells pose a cancer risk remains unsettled. Bjerkvig notes that a handful of other groups have published evidence that the stem cells can turn cancerous, but their papers also lack STR profiling to rule out contamination.

  6. ScienceNOW.org

    From Science's Online Daily News Site

    CREDIT: NASA/JPL/UNIVERSITY OF ARIZONA

    Martian Volcano Mud May Have Hosted Life They're not exactly prime real estate, but Martians may have called them home. The craterlike features in this image, taken by NASA's Mars Reconnaissance Orbiter, are not from comet or asteroid impacts. They're small volcanic cones about 250 meters wide, thousands of which dot a northern lowlands region of the Red Planet called Acidalia Planitia. Scientists analyzing the cones have concluded that their centers are filled with sediments that once harbored water. The muddy layers were ejected from deep under the surface possibly billions of years ago. If so, the team reports in this month's issue of the journal Icarus, the mud could have contained enough organic materials to support primitive forms of life. Even if the sediments turn out to be lifeless, they could reveal more about the planet's chemical and geological history.

    Hair Follicles Track the Body's Clock Those red-eye flights and all nighters may be leaving their mark in your hair. Researchers have found that hair follicles contain a signature of the 24-hour circadian clock that sets our sleeping habits. The finding could provide a painless way to monitor patients with sleep disorders or study health problems in shift workers.

    CREDIT: NATSUKI KIMURA

    Makoto Akashi of Yamaguchi University in Japan and his colleagues disrupted the sleep-wake cycle of healthy volunteers until, after 3 weeks, they were waking up about 4 hours later than normal. Then they checked how the disruption affected the activity of the volunteers' circadian clock genes. Rather than draw blood or take skin samples several times a day, the team examined RNA from the cell-rich follicles of hairs plucked from scalps or beards. The activity of the hair follicles' circadian genes had shifted along with the sleep patterns— but only by about 2½ hours, the team reports in the Proceedings of the National Academy of Sciences.

    Akashi's group saw a similar lag of about 5 hours in shift workers who switched from the morning shift to the evening shift and back over 3 weeks, indicating that that wasn't enough time for their body clocks to adjust to the new schedules.

    CREDIT: TORSTEN WAPPLER; DAVID HUGHES

    Zombies Thrived on Ancient Earth Zombies have roamed Earth for at least 48 million years. Zombie ants, that is. Today, Ophiocordyceps fungi are well known for taking over the minds of ants such as the Camponotus leonardi worker pictured above. Once infected, an ant wanders away from its colony, bites down on a leaf vein near the forest floor, and dies—creating ideal conditions for the fungal fruiting body that sprouts from its corpse. Only parasitized ants perform this routine, and the bite marks they leave are so distinctive that they're recognizable even in fossil foliage, researchers report in Biology Letters. The ancient leaf pictured bears 29 scars that represent the last acts of up to seven ants, probably close relatives of the modern Camponotus zombies. That makes the leaf the first known fossil evidence of zombie behavior in any animal.

    CREDIT: ARNE-R. DIERCKS/NIUST/NOAA

    Bacteria Are Gobbling Gulf Oil Last week, oceanographer Richard Camilli and colleagues at the Woods Hole Oceanographic Institution in Massachusetts sounded a cautionary note on the gulf oil spill: They reported in Science that measurements of oxygen dissolved in seawater indicated that microbes had not appreciably degraded the oil during its first 5 days out of BP's blown well (http://bit.ly/camilli). Now a new study offers some reassurance: The bugs are flocking to the remaining crude in droves, though it's not clear how quickly they're digesting it.

    Microbiologist Terry Hazen of the University of California, Berkeley, and colleagues pulled samples of seawater from a plume 1100 meters beneath the surface and the uncontaminated area surrounding it. Microbes were more than twice as dense inside the plume as outside it; what's more, genes specifically geared to degrade hydrocarbons were more common in the plume, the team reports online in Science. The team estimates that the bugs could cut concentrations of one type of hydrocarbon, alkanes, in half within a week.

    But oil is made up of dozens of other hydrocarbons as well, other researchers point out, and it's unclear how long they'll remain.

    Read the full postings, comments, and more at news.sciencemag.org/sciencenow.

  7. Chemistry

    Organizers Panned for Omitting Israelis From Meeting in Jordan

    1. Robert F. Service

    Political tensions between Israel and the Arab world are threatening to overshadow an upcoming chemistry conference in Jordan. The verbal sparring has already created plenty of raw feelings and led to much finger-pointing.

    Local organizers for the 11th Eurasia Conference on Chemical Sciences aren't saying why they didn't invite any speakers from Israel, which borders Jordan and has the region's largest chemical research enterprise. But one Israeli scientist calls the snub “intentional,” and few, if any, have registered for the conference. Roald Hoffmann, a chemistry Nobel laureate at Cornell University who was among the more than 100 chemists invited to speak at the meeting, is outraged at what he views as an encroachment of politics into science. He's asked fellow invited speakers to boycott the meeting unless the organizers invite Israelis. Conference organizers, in turn, say it is Hoffmann who's playing politics and that they won't be bullied into revising their plans.

    Begun in 1988, the conference gives young scientists in developing countries a chance to rub elbows with world-class researchers. Israeli scientists have been speakers and participants at previous meetings, which are held every 2 years in developing countries throughout Asia and the Middle East. The 2008 meeting in the Philippines, for example, featured a plenary talk by Aaron Ciechanover, a Nobel laureate at the Israel Institute of Technology in Haifa.

    Not this year. After accepting an invitation to speak at the meeting, Hoffmann was asked to help organize a workshop to run concurrent with the 6 to 10 October conference. He and fellow chemistry Nobelist and workshop organizer Dudley Herschbach discovered that none of the workshop participants was from Israel and asked conference organizers to reach out to Israeli students. Then they learned that the workshop had been canceled.

    “That's when I became suspicious,” says Hoffmann, who calls the absence of Israeli invited speakers at the main conference “preposterous.” He tried a back-channel effort, which failed. That's when he called for a boycott.

    Other chemists from Israel and elsewhere agree that the absence of Israelis on the list of invited speakers is glaring, given their regional prominence. “To ignore Israel is something very visible,” says Ehud Keinan, president of the Israel Chemical Society and a chemist at the Israel Institute of Technology.

    In response to Hoffmann's concerns, the chair of the conference's national organizing committee, Musa Nazer, e-mailed the invited speakers to explain that they were chosen not by nationality but “based on nominations and consultations with eminent chemists, topics of the conference, available slots in the program,” and other criteria. It was too late to make changes in the lineup, he added. “We wish to emphasize that inviting speakers at the present stage under pressure and threat does not enhance a positive atmosphere for this conference or any conference of this caliber,” the letter concludes.

    Hoffmann isn't just urging a speaker boycott. He also wants the International Union of Pure and Applied Chemistry (IUPAC) to withdraw its support. Joshua Jortner, former president of the Israel Academy of Sciences and Humanities, has asked IUPAC to investigate the issue and to push for the inclusion of Israelis among the featured speakers.

    No-show.

    Roald Hoffmann says the lack of Israeli speakers is “preposterous.”

    CREDIT: GARY HODGES

    That's not going to happen, according to IUPAC President Nicole Moreau. In a letter to Hoffmann, Moreau says she is not considering withdrawing IUPAC sponsorship for the conference. The choice of invited speakers is not among the list of criteria for IUPAC's sponsorship of a conference, she says, and withdrawing support based on the exclusion of speakers from a particular country would set an unwelcome precedent.

    Jortner, also a former president of IUPAC, says he's disappointed by the response. He notes that the United Nations Educational, Scientific and Cultural Organization pulled its sponsorship from a 2008 geological sciences meeting in Jordan following similar complaints. “I strongly feel the same attitude must be applied right now,” Jortner says.

    Others are looking for a way to defuse the tension. “I don't want to inflate this episode to levels where [the damage] would be irreversible,” Keinan says. In fact, last week Keinan sent a letter to the approximately 1000 chemical society members encouraging them to consider attending the meeting.

    “It's extremely frustrating for everybody,” says Bernd Rode, one of the conference's founders and a chemist at the University of Innsbruck, Austria. Even if nothing changes before the meeting, Rode says, conference organizers will hold a panel discussion to allow participants to discuss the issue thoroughly.

  8. U.S. Science Policy

    NSF Turns Math Earmark on Its Ear to Fund New Institute

    1. Jeffrey Mervis

    When Congress tells a federal agency to spend money on a particular project not in its budget request—a process called earmarking—the agency generally has little choice but to comply (Science, 20 August, p. 892). The National Science Foundation (NSF), however, has quietly folded one recent earmark into a competitive grants program, eliminating what seemed to be one state's advantage. Even more surprisingly, NSF apparently has done it without incurring the wrath of that state's senior legislator: Majority Leader Harry Reid (D–NV), the most powerful member of the U.S. Senate.

    Counted out.

    Majority Leader Harry Reid fell short in his attempt to obtain a new math institute for Nevada.

    CREDIT: U.S. SENATE

    In March 2009, Reid inserted language into a spending bill that gave NSF $3 million “to establish a mathematical institute devoted to the identification and development of mathematical talent and to advance mathematical topics critical to the national interest” (Science, 20 March 2009, p. 1548). Reid wanted to build upon the work of the Davidson Academy, a one-of-a-kind public school for exceptionally gifted middle- and high school-aged students on the campus of the University of Nevada, Reno.

    Coincidentally, NSF's Division of Mathematical Sciences (DMS) had just put out a solicitation for a new round of funding for its biggest single program, a network of seven mathematics institutes at universities around the country (mathinstitutes.org). Rather than simply complying with Reid's directive, it added his earmark to the $20 million set aside for the new competition.

    The solicitation attracted proposals from the four existing institutes—at the University of California, Berkeley, UCLA, University of Minnesota, and Ohio State University—whose funding was about to expire, along with various newcomers. Among the latter was a team of educational psychologists from the University of Iowa, Johns Hopkins University, and the Davidson Institute for Talent Development in Reno. The group proposed an institute to serve the tiny population of “profoundly gifted” precollege students that Reid had in mind.

    This month, NSF announced the results of the competition: The four incumbents won a new round of funding, and a fifth institute, the Institute for Computational and Experimental Research in Mathematics (ICERM), will be created at Brown University. ICERM's director, mathematician Jill Pipher, says the 5-year, $15.5 million award will allow researchers to “integrate math and computation” by fostering collaborations aimed at developing advanced search tools that tackle problems in fields such as health care and national security.

    What happened to Reid's idea of an institute for math prodigies? Although many of the existing institutes work with elementary and secondary school students and teachers, those activities generally are not supported by their grant. Nor will they be the focus of the Brown institute. “DMS wants to fund mathematical research, starting at the undergraduate level, and that's the core mission for us,” says Pipher, an expert in cryptography. “At the same time, the interaction of mathematics and computers has the potential to attract young people.”

    Although the Brown institute will cater to professional scientists and mathematicians, NSF officials believe that they have fully addressed the second part of Reid's request to create a math institute that addresses critical national interests. “We feel that the Brown proposal satisfies that language,” says the division's deputy director, Deborah Lockhart.

    NSF's decision appears to be okay with Reid. “Although Sen. Reid included language in the 2009 Appropriations bill encouraging the NSF to provide more opportunities for gifted students,” his Nevada press secretary, Tom Brede, e-mailed Science after the Brown institute was announced on 5 August, “the decision to award grants was made by a peer-review panel. He is pleased that the NSF was able to expand the number of mathematics research institutes.”

    Iowa's Susan Assouline is disappointed but not surprised by NSF's decision. “They weren't interested in thinking outside the box,” she says about NSF's reviewers. “We were a university-based project that would be serving K-12 students. That was a hard concept to get across.” Assouline says her team has obtained other funding to continue its work with this special population and has no plans to approach NSF again.

  9. ScienceInsider

    From the Science Policy Blog

    As this issue of Science went to press, a court decision earlier this week temporarily blocking federal funding for work with human embryonic stem cells (hESCs) has left some researchers working with the cells facing a cutoff of funding.

    U.S. District Judge Royce Lamberth issued a temporary injunction on 23 August blocking the National Institutes of Health (NIH) from implementing its hESC guidelines. In his 15-page ruling, Lamberth said that hESC research “necessarily depends upon the destruction of a human embryo.” He cited a law called the Dickey-Wicker Amendment that bars federal funding for research that destroys human embryos, saying the government cannot fund work with hESCs. The ruling came as part of a lawsuit filed by Christian groups and two doctors opposed to embryo research.

    NIH Director Francis Collins said that researchers who had already received grant money this year to study hESCs could continue their 200 or so projects. But more than 60 grants in review have been pulled aside, and 22 funded investigators awaiting their annual payment in September may not receive it.

    Harvard University confirmed last week that cognitive scientist Marc Hauser is on leave after having been found guilty of eight counts of scientific misconduct. A number of papers will have to be retracted or corrected, including one published in Science (7 September 2007, p. 1402) that is being reviewed. Two federal research agencies that have funded his work have launched their own investigations, as has the Department of Justice.

    The U.S. biomedical research community is reacting with concern to a proposal from the National Institutes of Health to clamp down on financial conflicts of interest. In more than 170 comments, many universities, groups, and individual scientists urge NIH to limit the information requested in a proposed regulation. They also think the government should create a central public database for disclosing conflicts.

    For more science policy news, visit news.sciencemag.org/scienceinsider.

  10. Archaeology

    Google Earth Shows Clandestine Worlds

    1. Heather Pringle*
    Secret no more.

    A new study charts Gitmo's growth from April 2003 (inset) to November 2004.

    CREDIT: GOOGLE EARTH 2010; (INSET) GOOGLE EARTH/DIGITALGLOBE/EUROPA TECHNOLOGIES 2010

    The prison camp at the U.S. Naval station in Guantánamo Bay, Cuba, has been a secretive proposition from the start. The U.S. government has never released official information on the size of the camp or the layout of its buildings. The 176 detainees still there are not permitted to speak directly to journalists.

    For human-rights advocates, Gitmo is terra incognita, a place of many unknowns, and its clandestine nature and location on foreign soil have helped fuel suspicions about the treatment of detainees there. In a new study published in World Archaeology this week, archaeology Ph.D. student Adrian Myers of Stanford University in Palo Alto, California, strips away part of the secrecy. By analyzing a series of satellite images easily accessible on Google Earth, Myers has drawn the first independent map of Gitmo and charted its explosive growth over the past 7 years. “He has taken the archaeological eye and turned it on Google Earth images of a heavily clouded political prison,” says cultural anthropologist David Price of St. Martin's University in Lacey, Washington. “And this is telling us something about what's going on at Gitmo.”

    Myers's analysis of the prison is one of an eclectic array of archaeological studies that use Google Earth—an inexpensive online service combining satellite images and maps—to explore concealed activities and to push the boundaries of archaeological research. Researchers are using the software to track looting on an unprecedented scale, for example, scrutinizing sites scattered across Jordan. And in war-torn Afghanistan, where ground surveys are too dangerous, Google Earth's images allow archaeologists to virtually field-walk huge swaths of terrain and survey for new sites.

    Archaeologists have used satellite images since the 1980s, but the current projects would be unthinkable with expensive commercial satellite imagery, which also requires remote-sensing expertise. Google Earth doesn't work well everywhere, but in some places it is spurring archaeologists to venture into entirely new fields. The looting studies, for example, are “a great first step in raising public awareness of the problem,” says archaeologist Morag Kersel of DePaul University in Chicago, Illinois, “and it shows that Google Earth can be used for a lot more than identifying your own backyard.”

    Concrete expansion.

    Gitmo exploded in size

    CREDIT: U.S. DEPARTMENT OF DEFENSE 2006

    Myers began studying Google Earth images of Guantánamo Bay in April 2009 while gathering data for his dissertation on the archaeology of internment camps. At first, he wondered whether he would be able to see the prison, given that Google Earth gets images from private companies that are subject to laws restricting the release of images of military installations and other sensitive places. Myers expected Gitmo to be blurred out. But it wasn't. “When I navigated there,” he says, “I remember saying, ‘Holy crap, you can see it.’”

    Myers downloaded Google Earth's high-resolution images of Gitmo taken on three dates between April 2003 and February 2008. He then loaded them into a geographical information system and identified features such as roads, guard towers, and barbed wire fences. To better interpret what he was seeing, he compared the satellite images with official ground photos of the prison and with plans he found in a leaked government report. “That was key,” says Susan Wolfinbarger, a remote-sensing expert at the American Association for the Advancement of Science (which publishes Science). “That extra contextual information helps you to interpret it.”

    By comparing the dated satellite images, Myers traced the prison's evolution. Initially, the government built temporary plywood barracks surrounded by chain-link fences. But as the war dragged on, it built a more permanent facility, Camp Delta, that contained structures closely resembling concrete supermaximum-security prisons. It also significantly expanded Gitmo. Over a 5-year period beginning in April 2003, the number of prison structures soared by nearly 40%; floor space expanded from 42,920 to 61,558 square meters, an increase of about 40%.

    Myers thinks the makeshift prison in 2003 reveals how the U.S. military was caught off-guard by the war on terror, capturing suspects before it had prepared a prison, and that the later building boom signaled an intention to hold prisoners for a long period. Given the many questions that human-rights groups have raised about the covert prison over the years, adds Wolfinbarger, it's somewhat surprising that an archaeologist was the first to map it: “I can't believe that someone in geography didn't think to do this.” (A Pentagon spokesperson declined to comment on Myers's study and said she could not confirm that the images were of Gitmo.)

    Looting's big picture.

    Google Earth images revealed the extent of looters' pits (outlined in red) in Jordan.

    CREDIT: DANIEL CONTRERAS/GOOGLE EARTH 2008

    Myers argues that his study serves the public interest by creating an independent record that cannot be erased later. “These kinds of prison camps disappear really quickly when their use is up,” he says. “After the Second World War, the American government tried to strip away and bulldoze the Japanese-American internment camps.”

    He notes, however, that using Google Earth images raises ethical issues. Google Inc. does not ask landowners for permission to post online satellite images of their property, including military bases. That policy could potentially violate privacy rights or jeopardize national security.

    Google says it isn't revealing anything that it shouldn't. By law, the United States government can exert shutter control over all commercial remote sensing carried out by U.S. companies, including the ones that supply images to Google. “The government could block or alter the images if it wanted to, but it chooses not to,” says Google spokesperson Kate Hurowitz.

    While Myers uses Google Earth to examine a secretive prison, others are using the technology to peer into another covert world: the illegal trade in antiquities. Archaeologists have long lacked hard data on the extent and intensity of looting worldwide, which they say makes it more difficult to persuade policymakers to take action. And in the past, attention has often focused on the plundering of single artifacts such as the Euphronios Krater, a finely painted bowl looted from an Etruscan tomb.

    Noting an abundance of Jordanian antiquities in British shops, archaeologist Daniel Contreras of Stanford University and independent archaeologist Neil Brodie wanted to quantify the extent of looting in Jordan. They calculated that using commercial satellite imagery would require between $0.9 million and $2.5 million, plus considerable remote-sensing expertise. They lacked both, so they settled on Google Earth, which has imagery only in visible wavelengths but is cheap and comes with map coordinates. They found that much of Jordan was covered by high-resolution images, representing less than 1 meter per pixel.

    The pair located known sites on the images by importing a digital archaeological atlas into the $400 Google Earth Pro software. Then they looked at ancient cemeteries and sites near roads for telltale traces of pitting. They found 25 heavily looted sites, calculated their area, and ground-truthed the results by visiting 16 sites.

    In all, they determined that 51 hectares of Jordan's known archaeological sites had been destroyed by looters as of 2007. Their report this year in the Journal of Field Archaeology is the first “really graphic, quantitative data on the scale of looting there,” says Brodie. Since then, Contreras has used Google Earth images to measure 47 hectares of looting in one valley in Peru, as he reported in the June issue of Antiquity.

    Contreras believes that Google Earth will help focus attention on the broader picture of looting. The new studies reveal the scale of the problem “that goes far beyond the loss of individual contexts,” he says. He's now looking into the feasibility of a Google Earth crowd-sourcing project, recruiting citizens to examine online images for surges in looting.

    While Contreras and others scan for looters, others are using Google Earth to search for new archaeological sites. La Trobe University Ph.D. student David Thomas put in his last field season in Afghanistan in 2005; after that, security concerns and bureaucracy prevented fieldwork. But Afghanistan has a rich past, with large areas virtually unknown to archaeologists. So Thomas decided to survey the countryside with Google Earth.

    He and his small team started off by analyzing imagery of 45 known medieval sites. While they were mapping a massive fortress known as Qal'a-i Hauz—the only recorded site in Afghanistan's Registan Desert—they decided to prospect for new sites to the north. Poring over images encompassing 1367 square kilometers, the team identified 451 possible new sites in the harsh desert, ranging from small burial mounds and single-family dwellings to deserted villages, reservoirs, and subterranean canals. The images were so clear and detailed, says Thomas, that “you could even tell the buildings that were mosques because they had a mihrab [a bulge in the western wall that contains a prayer niche] pointing toward Mecca.” Their work was published in the Aerial Archaeology Research Group News in 2008.

    Thomas's team now needs to ground-truth and date the sites. But already, he says, the project has demonstrated the importance of surveying deserts and other inhospitable regions. Although Google Earth images can't be used everywhere—the image resolution varies from place to place, and some images just show thick cloud cover—he considers them a cheap and effective way to search for sites in Afghanistan. “I think the potential is huge,” he concludes. “There are 46,000 square kilometers of high-resolution Google Earth images for Afghanistan, and all we've done is look at less than 1% of that.”

    • * Heather Pringle is a contributing editor at Archaeology magazine.

  11. Infectious Disease

    From Pigs to People: The Emergence of a New Superbug

    1. Dan Ferber

    The first infection was puzzling, almost inexplicable. In July 2004, Andreas Voss of Radboud University Nijmegen Medical Center in the Netherlands admitted a 6-month-old girl for surgery to repair a congenital heart defect.

    Because an infection with the common bacterium Staphylococcus aureus would pose a grave risk following heart surgery, Voss and his colleagues screened the baby girl for the microbe. They found not just S. aureus but also a menacing drug-resistant form known as methicillin-resistant S. aureus (MRSA). The physicians were flummoxed. Although MRSA has reached epidemic proportions in much of the developed world, MRSA infections are rare in the Netherlands, thanks to an aggressive “search and destroy” policy the country launched in the mid-1990s to screen for the superbug in health-care settings, where it most frequently spreads. In the Netherlands now, the biggest risk for MRSA infection is a stay in a germ-ridden foreign hospital.

    At risk.

    Pigs in confinement barns can harbor MRSA. A few farm families have contracted dangerous infections.

    CREDIT: GLEN STUBBE/LANDOV

    But this baby girl had never left the country. “We couldn't find a single source” of exposure, Voss recalls. But there was one clue: Her parents were pig farmers.

    Within weeks, a second MRSA-colonized patient appeared at the hospital: another pig farmer. Then a third: the child of a veterinarian who worked only with pigs. “It was dumb luck I would say,” Voss recalls. “We had within a short time three unexpected cases that all had pig written on them.”

    Pigs and other livestock commonly, and generally harmlessly, harbor S. aureus. But except for a single report buried in the scientific literature, no one had realized that pigs or other livestock harbored MRSA, and no MRSA strain had ever been known to jump from livestock to humans. If the Dutch doctors' fears were correct, a novel strain had just gained that ability, opening up a new route for a potentially dangerous superbug to spread among humans. “Initially, we were very much afraid that this would be a major problem that could spread to the entire population,” says Jan Kluytmans, a microbiologist at VU University Medical Center in Amsterdam whom Voss recruited early on to help investigate.

    Index case.

    MRSA from pigs on Eric and Ine van den Heuvel's farm was detected in their daughter, Eveline, when she was an infant.

    CREDIT: MARIEKE VAN DEN HEUVEL

    In recent months, the dangers of livestock-associated MRSA have been played up in controversial media reports, including a special series by CBS Evening News, as a consequence of the livestock industry's indiscriminate use of medically important antibiotics to fatten livestock. Such uses can lead S. aureus and other bacteria to swap whole sets of resistance genes, potentially transferring resistance to antibiotics like methicillin that haven't even been used in agriculture.

    Such awareness has fueled a push to restrict this long-debated use of antibiotics; this summer, the U.S. Food and Drug Administration has proposed to phase it out. Industry is opposed, saying the risk is negligible. Both sides are using the emergence of this new superbug to bolster their cases.

    So far, the worst fears about the strain have not been realized. It did jump from pigs to people, scientists determined through gumshoe detective work. And it has caused serious disease—although rarely—among farmers and veterinarians who work with pigs and other livestock, and their families, although most of them carry the microbe harmlessly in their noses. But it doesn't appear to be readily transmissible between humans, so the chance of a broad community epidemic seems low.

    However, MRSA readily mixes and matches genes with other bacteria that make it more virulent, more transmissible, and harder to treat—and this newly emerged strain could take that route too. “Is it something to worry about? Absolutely,” says infectious-disease specialist Vance Fowler of Duke University Medical Center in Durham, North Carolina.

    A growing menace

    MRSA appeared first in hospitals, where medical procedures can ferry bugs into the unprotected interior of the body and patients are particularly vulnerable to infection. Until the 1990s, it posed only a mild threat, and the vast majority of S. aureus infections remained sensitive to methicillin. But since then, MRSA strains have increasingly displaced sensitive S. aureus strains and acquired resistance to other antibiotics, making hospital infections far more dangerous (Science, 18 July 2008, p. 356). Today, S. aureus accounts for about 20% of all hospital bloodstream infections in the United States, and 65% of the S. aureus infections in intensive-care units resist methicillin, among other antibiotics. MRSA killed approximately 18,650 Americans in 2005, researchers from the U.S. Centers for Disease Control and Prevention (CDC) reported in The Journal of the American Medical Association in 2007, a higher death toll than that of HIV/AIDS.

    For years, the most dangerous strain of MRSA remained inside hospitals. Some strains began to circulate in the wider community, mostly among people in tight spaces such as prisons, and those with a lot of skin contact, such as family members and participants in contact sports. They were largely considered a nuisance, far less dangerous than hospital-acquired infections, mostly because they infected healthy people whose skin and immune defenses kept them from infiltrating the body, and they were easier to stop with antibiotics.

    Since the 1990s, however, community-acquired MRSA has grown more menacing, picking up genes that make it more virulent and resistant to an increasing variety of antibiotics. Most life-threatening infections still occur in hospitalized patients or those who have undergone outpatient treatments such as dialysis or surgery. But each year in the United States, community-acquired MRSA causes about 13,000 infections serious enough to require hospitalization and more than 1400 deaths, according to the 2007 CDC report. What's more, the lines between hospital-associated and community-associated strains are blurring, as strains formerly limited to the hospital have begun colonizing healthy people, and strains once limited to the community now sicken many patients in hospitals.

    So when the livestock-associated strain showed up in people, public experts had no idea how risky it might be or become.

    A peculiar strain

    The three isolates from the Nijmegen hospital turned out to be from a single strain, which researchers now call ST398.

    With permission from the young patient's father, Voss's team cultured bacteria from pigs on his farm and did a quick and dirty test on him and 25 of his pig-farming colleagues. Within 2 months of the girl's admission, they'd learned that one in four was asymptomatically carrying MRSA, compared with just 0.03% of the general Dutch population. Although crude, the analysis provided pretty strong evidence that the bug had come from pigs.

    To confirm that route of transmission, Kluytmans and Voss did a case-control study that examined years' worth of MRSA infection data housed at the Dutch national microbial reference center. In 2007, they reported in Emerging Infectious Diseases that those who carried ST398 were 12 times more likely to be pig farmers than nonfarmers and that almost all the MRSA from farmers belonged to strain ST398. Cattle farmers were also 20 times more likely to carry the strain. The strain has since turned up in chickens, horses, dogs, and cats, posing a potential but poorly understood threat to humans.

    Soon scientists in two other European pig-farming hot spots, Denmark and Germany, began finding the strain in their backyards. And in 2008, medical microbiologist Robert Skov of the Statens Serum Institut in Copenhagen reported a case-control study in Emerging Infectious Diseases that showed that the strain had spread in Denmark and was clearly linked to pig farming there as well.

    Follow the pork.

    In the Netherlands, rates of human infections with MRSA strain ST398 tracked with pig populations (top), while rates of other MRSA strains tracked with human populations (bottom).

    CREDIT: ADAPTED FROM I. VAN LOO ET AL., EMERGING INFECTIOUS DISEASES 13, (DECEMBER 2007)

    No one knew then how virulent the strain was, but some of the data were and remain concerning. Case reports continue to appear of MRSA strain ST398 causing minor skin and soft tissue infections as well as mastitis, severe wound infections, pneumonia, and even some flesh-eating disease in countries throughout Europe. To date, Voss has seen about 10 cases of severe bloodstream infections of ST398 and two ST398 infections following hip-replacement surgery.

    More recently, researchers have tested how readily ST398 can spread among humans and have learned, somewhat reassuringly, that it does not spread easily beyond farms. Medical microbiologist Wolfgang Witte's team at the Robert Koch Institute in Wernigerode, Germany, tested at a school in North-Rhine Westphalia, an area of Germany where pigs are farmed intensively, figuring that if the strain spread among healthy people, it would likely show up among schoolchildren who spend each day together. The team reported last year in PLoS ONE that while 250 of 462 students at the school were positive for some sort of S. aureus, only three carried ST398 MRSA in their noses, and all three lived on pig farms.

    ST398 is also spreading on farms in North America, according to a handful of recent studies. For example, last year Tara Smith of Iowa State University in Ames and colleagues reported in PLoS ONE that nearly half the hogs and 45% of the workers on a Midwestern hog farm were colonized with ST398. But the strain seems less menacing in North America than it is in Europe. Only one farm worker in Smith's study became ill. And microbiologist Michael Mulvey's team from Canada's National Microbiology Laboratory in Winnipeg reported in Emerging Infectious Diseases in April that only 0.25% of the 3687 MRSA isolates from people infected in Manitoba and Saskatchewan were strain ST398. Researchers speculate that the transatlantic difference may simply be due to the fact that ST398 got a head start in Europe, or it may face more competition in the United States and Canada from other human-adapted MRSA strains.

    Opinion is divided on whether ST398's behavior so far provides reassurance about its future conduct. Brandi Limbago of CDC, who tracks infection-causing MRSA strains in the United States, says that “for now I think it's a nonissue in this country.” But others, such as Fowler of Duke, warn that it is too soon to sound the all clear. Half the swine herd in the Iowa study was carrying ST398, he points out. That's a lot of pig noses. And the strain could yet adapt and become more dangerous, just as community-acquired MRSA has done. That's why ST398 needs to be carefully monitored, says veterinary microbiologist Gail Hansen of the Pew Health Group in Washington, D.C. “Sometimes these things don't become a problem, but you don't want to take your eye off the ball.”

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