News this Week

Science  28 Apr 2006:
Vol. 312, Issue 5773, pp. 508
  1. ARCHAEOLOGY

    New Carbon Dates Support Revised History of Ancient Mediterranean

    1. Michael Balter

    During the Late Bronze Age, the Aegean volcanic island of Thera erupted violently, spreading pumice and ash across the eastern Mediterranean and triggering frosts as far away as what is now California. The Theran town of Akrotiri was completely buried. Tsunamis up to 12 meters high crashed onto the shores of Crete, 110 kilometers to the south, and the cataclysm may ultimately have sped the demise of Crete's famed Minoan civilization. For nearly 30 years, archaeologists have fought over when the eruption took place. Those who rely on dates from pottery styles and Egyptian inscriptions put the event at roughly 1500 B.C.E., whereas radiocarbon experts have consistently dated it between 100 and 150 years earlier.

    Figure

    Now, two new radiocarbon studies on pages 548 and 565 claim to provide strong support for the earlier dates. The studies “convincingly solve the problem of the dating of the Thera eruption,” says archaeologist Colin Renfrew of Cambridge University in the United Kingdom, who was not involved in the work. If correct, the earlier dates would have “major consequences” for the relationships between Egypt, Minoan Crete, and Mycenaean Greece, says archaeologist Jeremy Rutter of Dartmouth College: “The issue of which direction artistic and other cultural influences was traveling may change significantly.”

    But many archaeologists who have long defended the later dates are unmoved. “I am not impressed,” says Egyptologist Manfred Bietak of the University of Vienna in Austria, who prefers to rely on detailed Egyptian records for the same period. Archaeologists on both sides agree on one thing: The pottery found at Akrotiri since Greek archaeologists began excavating there during the 1960s has a distinctive style featuring spirals and floral motifs, known as Late Minoan IA (LM IA). The LM IA period also corresponds to what archaeologists consider the height of Minoan civilization. Because pottery was widely traded across the Mediterranean, sites that have pottery styles later than LM IA—such as Late Minoan IB, which features depictions of dolphins, octopi, and other sea creatures—must postdate the eruption. This makes it possible to construct relative chronologies for the region despite the debates over absolute dating.

    One team, led by archaeologist Sturt Manning of Cornell University, dated 127 radiocarbon samples from Akrotiri and other Aegean sites thought—based on relative chronologies—to span a period from about 1700 to 1400 B.C.E. Manning and colleagues used a new radiocarbon calibration curve (described last year in the journal Radiocarbon) as well as sophisticated statistical models and cross-checked some samples among three different dating labs. They dated the eruption to between 1660 and 1613 B.C.E., within 95% confidence intervals.

    That's a fairly close match to the findings of a second team, led by geologist Walter Friedrich of the University of Aarhus in Denmark. In 2002, Friedrich's graduate student Tom Pfeiffer found an olive branch, complete with remnants of leaves and twigs, that had been buried alive in pumice from the eruption. Radiocarbon dating fixed the death of the branch's outermost ring, and thus the eruption of Thera, between 1627 and 1600 B.C.E., again at 95% confidence levels. The authors of both papers argue that these earlier dates rule out the “conventional” chronology of about 1500 B.C.E.

    “That is great news about the olive tree,” says dendrochronologist Peter Kuniholm of Cornell, although he cautions that it is more difficult to assign specific years to the rings of a slender olive branch than to more commonly used trees such as conifers and oaks. Archaeologist Gerald Cadogan of the University of Reading, U.K., adds that the dates given by the two papers are “pretty consistent” and that their validity is bolstered because they are “put in context by other dates from before and after from elsewhere in the Aegean.”

    Manning and colleagues say the early dates suggest that the conventional linkage between Minoan and Egyptian chronologies, which puts the apex of Minoan civilization contemporaneous with Egypt's 16th century B.C.E. New Kingdom, is wrong. The New Kingdom, especially during the rule of Pharaoh Ahmose, was the high point of Egyptian power. Rather, the Minoans would have reached their own heights during the earlier Hyksos period, when the Nile delta was ruled by kings whose ancestors came from the Levant. Rutter says Egyptologists have tended to discount the importance of the Hyksos, whom Ahmose eventually chased out of Egypt: “The Hyksos have gotten lousy press.”

    This chronological realignment would also mean that the famous gold-laden Mycenaean Shaft Graves—excavated by German entrepreneur Heinrich Schliemann in the late 1800s and known to correlate with the LM IA period as well as the beginnings of Mycenaean power in the Aegean—would also be contemporaneous with the Hyksos. Some archaeologists had speculated that the Mycenaeans owed their rise to a strategic alliance with the New Kingdom; the new radiocarbon dates would instead raise the possibility that they were allied with the Hyksos, Rutter says. At the very least, Manning says, “it would make the Hyksos world much more important and interesting.” Manning adds that the earlier chronology would create “a different context for the genesis of Western civilization.”

    But many proponents of the later chronology are sticking to their guns. The radiocarbon dates create “an offshoot from the historical Egyptian chronology of 120 to 150 years,” says Bietak. “Until the reasons for this offshoot are solved, we are chewing away at the same old cud.”

    Buried treasure.

    Excavations at Akrotiri have unearthed fabulous frescoes and distinctive pottery.

    CREDIT: ERICH LESSING/ART RESOURCES

    Bietak and others have argued that radiocarbon dating is not infallible and that the earlier date for the Thera eruption is contradicted by excavations in Egypt and on Thera itself. He and other archaeologists have found LM IA pottery in stratigraphic layers that Egyptian records date to later periods, and at Akrotiri they have unearthed a style of Cypriot pottery that apparently does not show up until the 16th century B.C.E. in Egypt. “There are no current grounds for thinking that the Egyptian historical chronology could be out by more than a few years,” says archaeologist Peter Warren of the University of Bristol, U.K. “This chronology has been constructed by hundreds of expert Egyptologists over many decades.”

    Nevertheless, Rutter says, the Science authors “have done what they can to overcome” the objections by advocates of a later date for Thera. And both sides agree that there is a lot at stake in the debate. Until it is resolved, Warren says, at least for the Late Bronze Age, “we would have to forget about serious study of the past and relationships between peoples.”

  2. STEM CELLS

    Court Rules in Favor of California Stem Cell Institute

    1. Jocelyn Kaiser

    A California court has ruled that a $3 billion initiative for funding stem cell research does not violate the state's constitution. The ruling, a widely expected victory for California's research institutions, means that bond sales can proceed so that the California Institute for Regenerative Medicine (CIRM) can fund grants. But the plaintiffs plan to appeal, so CIRM may remain hamstrung for at least another year.

    Triumphant.

    Robert Klein, chair of CIRM's board, is celebrating after a court ruled that California's stem cell initiative is constitutional.

    CREDIT: KURT ROGERS/SAN FRANCISCO CHRONICLE/CORBIS

    CIRM, created by Proposition 71 and approved by California voters in November 2004, was set up to fund research on human embryonic stem cells that is not eligible for federal support. The institute has gotten off to a slow start, however, because of lawsuits filed partly by groups opposed to embryo research. Last year, the California Family Bioethics Council and two taxpayer groups argued that CIRM and its board, the Independent Citizens' Oversight Committee (ICOC), are not operating as state agencies because they are not subject to full government oversight. The suit contended, for example, that because ICOC's membership includes scientists from institutions that may apply for grants, they represent their own interests and not those of citizens.

    On 21 April, Alameda County Superior Court Judge Bonnie Lewman Sabraw rejected these arguments. CIRM officials and ICOC “are operating in the same fashion as other state agencies,” the ruling says. ICOC members have filed financial disclosure forms, the committee has developed conflict-of-interest policies, and it has held public meetings, among other steps. The plaintiffs “have not shown that the Act is clearly, positively, and unmistakably unconstitutional. The Act and the bonds issued thereunder are valid,” Sabraw concluded.

    “We are extremely pleased,” said Robert Klein, chair of ICOC, in a statement. And even though the matter isn't over—appeals could take “at least a year,” says CIRM spokesperson Nicole Pagano—the institute is moving ahead, Klein notes. Earlier this month, CIRM issued its first $12.1 million in research training grants, using money raised by selling “bond anticipation notes” (Science, 21 April, p. 345). Klein will announce soon another $31 million from the same kind of bonds, Pagano says. (A separate federal lawsuit trying to block CIRM by arguing that fertilized eggs are “persons” was dismissed last year for lack of venue but has been appealed, Pagano says.)

    Researchers at California universities in line to receive CIRM funds are rejoicing, too. “We're happy,” says Michael Clarke, deputy director of the 4-year-old Stanford Institute for Stem Cell Biology and Regenerative Medicine. He adds, however, that although Stanford has raised other funds to start the institute's work, “its progress is slowed until CIRM is fully functional.”

  3. SCIENTIFIC COMMUNITY

    University Clears Chinese Biophysicist of Misconduct

    1. Hao Xin

    The leader of a team hailed for the discovery of an antibiotic peptide has been absolved of wrongdoing by his employer. At a press conference last week, Sichuan University in Chengdu, China, announced that allegations of “scientific fabrication” against Qiu Xiao-Qing are unfounded, according to an investigation by a university expert group.

    The controversy is unlikely to die down soon, however. The company whose staff leveled the charges has blasted the investigation as lacking “objectivity, fairness, and transparency” and has called on the Chinese government to mount its own inquiry. As Science went to press, it was unclear how the government would respond.

    In 2003, Qiu, a biophysicist at Sichuan University's West China Hospital, along with 17 co-authors described in Nature Biotechnology an engineered peptide with specific antibacterial properties. Chinese media touted the protein, “pheromonicin,” or “Ph-SA,” as a major breakthrough in antibiotics.

    Vindicated.

    Fraud allegations against Qiu Xiao-Qing are unfounded, a Sichuan University panel says.

    CREDIT: YAO YUAN/CHENGDU ECONOMIC DAILY

    Before publication, Qiu applied for a Chinese patent on the peptide and the process of making it. Sichuan NTC Holdings Limited agreed to pay West China Hospital a $250,000 licensing fee; it paid half up front and set up a subsidiary, Chengdu Yanghui Biotechnology, to make pheromonicin. After 2 years of failed attempts at production, Sichuan NTC started to question the patent's validity and refused to pay the second half of the licensing fee. A dispute broke out between Sichuan NTC and West China Hospital, escalating into a fraud allegation. Six of the authors of the 2003 paper wrote to Nature Biotechnology last December, alleging that pheromonicin was not “targeted … against specific bacteria” and asking that their names be withdrawn from the paper. Qiu has denied the charge and sued two critics for defamation (Science, 17 February, p. 937).

    After Sichuan University's news conference, Qiu told Science that the names of the six authors-cum-critics were added to the paper when they performed experiments in part to answer questions from Nature Biotechnology reviewers. Four authors are Sichuan NTC employees who had been assigned to Qiu's lab to produce pheromonicin for animal safety studies. The other two, of the National Sichuan Institute of Antibiotic Industry, carried out analyses of pheromonicin's antibacterial properties.

    In response to the misconduct charge, Sichuan University assembled a panel of experts in microbiology, biochemistry, and molecular biology to conduct experiments to determine whether “the ‘falsification’ charge … could be substantiated.” After 3 months of work, they found “no factual evidence” for falsification, according to a press release. University officials declined to name the panel members or comment further.

    Sichuan NTC is not impressed. In a statement, the company called on Sichuan University to release the full investigation report; it says it will refuse to recognize the panel's findings “without a review by government authorities.” But it's not clear what agency would handle such an appeal. “China should set up an official mechanism and rules to deal with allegations of academic misconduct,” says Yi Rao, a neurobiologist at Northwestern University's Feinberg School of Medicine in Chicago, Illinois.

    A separate inquiry has cleared the second corresponding author on the Nature Biotechnology paper, George Wu of the University of Connecticut Health Center in Farmington. Spokesperson James Walter says the Health Center's Committee on Research Misconduct found “no credible evidence” to support a misconduct allegation, and therefore “no investigation was conducted.” Nature Biotechnology is also reviewing the case and will make a decision after Sichuan University relays the investigation results to the journal.

    Sichuan University says it will sue those responsible for “irretrievable damage” to its reputation. Qiu, for his part, says the affair has made him loath to get involved in the business end of science: “My place is in the lab.”

  4. PLANETARY SCIENCE

    Simulation Suggests Peaceful Origin for Giant Planet's Weird Spin

    1. Govert Schilling*
    1. Govert Schilling is an astronomy writer in Amersfoort, the Netherlands.

    How do you knock over a planet? Easy: Just give it a glancing blow from a smaller object. That's how astronomers have always explained the strange fact that Uranus is lying on its side, with its spin axis almost parallel to its orbit around the sun. But an Argentine astronomer says violence is unnecessary: Uranus's axial tilt, along with the tilts of its fellow gas giant planets, can be explained by gravitational perturbations alone.

    For decades, astronomers have invoked giant impacts in the chaotic aftermath of the solar system's birth to account for the origin of the moon, the thin, rocky mantle of Mercury, and the formation of the rings of Saturn. Little wonder that they also thought a tangential collision could tip over a planet. In the case of Uranus, however, the collision scenario has one important downside: A sudden cosmic smash would have left its moons unscathed. Yet the orbits of Uranus's regular satellites are also tipped over—they still circle the planet in its equatorial plane. So any tilting collision must have happened during a very early, brief stage, when the planet was still enveloped in a thick disk of material from which the satellites would later condense. “The idea always seemed a little improbable to me,” says planetary dynamicist Scott Tremaine of Princeton University.

    Adrián Brunini of the National University of La Plata, Argentina, agrees. In this week's issue of Nature, Brunini presents computer simulations that show how the obliquities of the giant planets arise naturally from mutual gravitational perturbations. These were strong in the early history of the solar system, when the young planets were slowly changing orbits owing to their interaction with the remaining rubble in the solar nebula.

    Brunini started off with a migration scenario that has been shown to provide the best explanation for the current orbital layout of the outer solar system. In most of his simulations, Uranus ends up on its side, Saturn and Neptune achieve a reasonable tilt, and Jupiter stays almost upright, exactly as observed. The strong tilt of Uranus results from close encounters with Saturn that occurred at a time when an orbital resonance between Jupiter and Saturn greatly increased the eccentricities of the more distant giant planets.

    Sideways.

    Uranus's equator and the orbits of its rings and moons lie 98° from its orbital plane.

    CREDIT: JPL/NASA

    Tremaine says Brunini's results provide “active support for the idea that substantial migration has indeed occurred.” Theoretical astronomer Jack Lissauer of NASA's Ames Research Center in Moffett Field, California, says he is surprised by the very narrow range of resulting obliquity values in Brunini's computer runs: “It's very interesting to see how precisely his results agree with the actual values.” But although there's no reason anymore to believe that Uranus was knocked over by a planetary collision, Lissauer says such events can't be ruled out altogether. “There still could have been big things flying around to do the hits,” he says, “even before the formation of the satellite systems.”

  5. FRANCE

    Chemist Claims Innocence to Spying Charge

    1. Martin Enserink

    STRASBOURG, FRANCE—It started out like a spy movie. On the morning of Saturday, 8 April, a border police officer at the airport here found four vials containing a white substance in chemist Luu Bang's suitcase. Instead of flying to Paris, where he was supposed to catch a connection to China, Luu found himself arrested and questioned; his lab and home office were searched; and his employer, the National Center for Scientific Research (CNRS) filed a theft report with the police.

    Accused.

    Luu Bang's supporters say CNRS overreacted to Luu's failure to fill out paperwork.

    CREDIT: DJALIL LOOWAR

    Luu, 66, was released after 10 hours. But more than 2 weeks later, his career and reputation are still on the line. A judicial inquiry is ongoing, CNRS has sent him into immediate retirement, and he has had to defend himself against espionage charges in the press. Yet his only mistake, he says, was not filling out the proper paperwork for the vials, which contained well-known chemicals developed in his lab. “This has hit me like a meteorite,” he says. Colleagues, too, insist CNRS has overreacted to a common infraction.

    Born in Phnom Penh, Cambodia, to a family of Chinese origin, Luu came to France to study at age 18. He has worked at the CNRS Institute for Neurochemistry in Strasbourg for more than 35 years; his work currently focuses on compounds that can activate stem cells. The French consulate in Guangzhou, in southern China, had invited him to visit this month—and was paying his expenses—to foster Sino-French collaboration. Luu says consular officials knew he was bringing the vials, containing long-chain fatty alcohols, so that prospective Chinese partners could try them in their own labs. Although he admits he erred by not obtaining authorization first, Luu says the notion that he committed theft or espionage is absurd. The compounds have been described in the scientific literature and are patented by CNRS both in Europe and China, he says.

    But Philippe Piéri, who heads CNRS's Strasbourg office, says it was a “grave mistake” not to get permission to export the vials. “Scientists can't just do what they think is right, like in the 19th century,” he says. Luu has been retired 4 months ahead of the scheduled date, and he won't be allowed to work as an emeritus, Piéri says.

    The prosecutor's off ice in Strasbourg declined to comment on its investigation; Luu says he thinks it started petering out once it became clear that he had been invited to Guangzhou by French diplomats. But Luu, a French citizen who feels his loyalty was questioned because of his ethnic background, wants CNRS to retract its sanctions too.

    Luu's main defender is his Ph.D. supervisor Guy Ourisson, 80, a former president of the French Academy of Sciences. In a 20 April letter to CNRS Director General Arnold Migus, co-signed by six Strasbourg chemists including one Nobelist, Ourisson called the penalty “entirely out of proportion” and asked that it be lifted. Ourisson says he and others have unknowingly violated the same rules “dozens of times.” In Luu's case, he says, “CNRS seems to have acted on the general fear that China is out to rob us.”

  6. OCEANOGRAPHY

    Korea and Japan Clash Over Surveys

    1. Dennis Normile

    TOKYO—A little-known international agency that approves the names of sea-floor topographic features found itself caught in the middle of a high-stakes territorial spat last week between Japan and South Korea. The two countries have backed away from a confrontation over dueling surveys in disputed waters, at least for the moment. But the fate of survey data—and of the coveted territory itself—still hangs in the balance.

    The dispute centers on a cluster of islets, and the surrounding exclusive economic zone (EEZ), roughly halfway between South Korea and Japan. The islets are claimed by both countries. South Korea calls the outcroppings Dokdo and the body of water the East Sea. To Japan, they are Takeshima and the Sea of Japan. South Korea controls the islets thanks to a police garrison on one of the rocks. The nations are vying for rights to exploit fishing grounds and extract what may be substantial offshore deposits of methane hydrates.

    A rock by any other name.

    Korea and Japan are vying to exploit the natural resources off these isolated islets.

    PHOTO CREDIT: KWON JOO-HOON/AFP/GETTY IMAGES

    Partly because of the contretemps, the sea floor near the islets had not been surveyed since a Japanese-led effort in the 1970s—that is, until a South Korean expedition last year. South Korea's hydrographic survey “found many new [subsea] features,” including seamounts and troughs, says Seok-Chang Kwon, head of the Marine Research and Development Division of South Korea's Ministry of Maritime Affairs and Fisheries. “It's our right to name the features we found,” he says. The ministry was planning to propose Korean names for consideration at a 21 June meeting of the Sub-Committee on Undersea Feature Names of the General Bathymetric Chart of the Oceans, an organization that standardizes and publishes nautical information under the auspices of the Monaco-based International Hydrographic Organization (IHO) and UNESCO's Intergovernmental Oceanographic Commission. Naming a feature is “in general, first-come, first-served,” as long as there are good supporting survey data, says subcommittee chair Hans-Werner Schenke, a marine geologist at the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany.

    Officials in South Korea and Japan agree that the names of subsea features and the EEZ boundaries are separate issues. Nonetheless, both sides view the name game as giving weight to competing claims. After learning of South Korea's plans to propose names to IHO, Japan last week had dispatched two Coast Guard research vessels to gather data to support Japanese names. South Korea responded by sending 20 gunboats to patrol the disputed waters. Two days of tense negotiations yielded a compromise: Japan canceled its survey, and South Korea pledged to postpone proposing names. And the countries agreed to resume stalled talks on the EEZ boundaries.

    No matter the outcome, “the committee encourages the exchange of new survey data,” says member Lisa Taylor, a geophysicist with the U.S. National Oceanic and Atmospheric Administration in Boulder, Colorado. (Korea's National Oceanographic Research Institute has posted survey data on its Web site.) The information is useful not only for navigation, Taylor says, but increasingly for geographical, geological, and paleontological research as well.

  7. GENETICS

    Parasite-Resistant Mosquitoes: A Natural Weapon Against Malaria?

    1. Martin Enserink

    In a world where mosquitoes were resistant to infection with parasites, no human being would suffer from malaria. With that idea in mind, some researchers are trying to sneak resistance genes into mosquitoes and encourage those genes to spread through the population.

    But a paper on page 577 of this issue suggests that engineering resistance into mosquitoes may be unnecessary. In an endemic area in Mali, researchers found that many Anopheles gambiae mosquitoes—Africa's most important malaria vector—are already resistant to Plasmodium falciparum, the malaria parasite. Resistance appears to reside in one or more genes in a very small genomic region, the researchers found—and the mosquitoes that don't have those genes may just be the odd ones out.

    The surprising upshot, according to Matt Thomas of the Commonwealth Scientific and Industrial Research Organisation in Canberra, Australia: “Why put new resistance genes into mosquitoes if they already have their own?” Instead, maybe the goal should be to eliminate the minority population that's susceptible, Thomas says. Its implications aside, the study's combination of fieldwork and molecular genetics is “most wonderful,” says Sergey Nuzhdin of the University of California, Davis. “I'm very envious.”

    In the study, researchers from the University of Minnesota, the Fred Hutchinson Cancer Research Center in Seattle, Washington, Princeton University, and the University of Bamako in Mali set out to find genes that determine malaria resistance in nature, using a tried-and-true strategy: Look for variation in a trait within families, and then use genetic markers to discover where the corresponding genes are located.

    The group collected female mosquitoes inside huts in Mali and let each produce one generation of offspring. Then, they let the resulting pedigrees feed on blood from a malaria-infected villager; after 7 to 8 days, they sliced open the insects and counted the oocysts—a stage in Plasmodium's life cycle—inside the insect gut. The lower the number, the more resistant the individual.

    They discovered that a small region on the 2L chromosome of A. gambiae played an all-important role. The Plasmodium Resistance Island, as they dubbed it, contains almost 1000 genes. Using several techniques to shake out genes of relevance, they pinpointed one gene, APL1, that appears to play a particularly important role; when its action was blocked using RNA interference, mosquitoes became vulnerable to infection. Still, other nearby genes may be involved as well, says lead author Kenneth Vernick of the University of Minnesota, St. Paul.

    Filling up.

    Mosquitoes feed on malaria-infected human blood through a membrane. To researchers' surprise, many are resistant to the Plasmodium parasite.

    CREDITS: COURTESY OF K. VERNICK; NATURE GENETICS (23 APRIL 2006), DOI: 10.1038/NG1783

    What surprised the team most was how widespread resistance is; in 22 of 101 pedigrees, not a single insect became infected after supping on infected blood. Like many other researchers, Anthony James of the University of California, Irvine, assumed that most mosquitoes were naturally susceptible to malaria infection—“until I read this paper,” he says. James leads a consortium that has received almost $20 million from the Bill and Melinda Gates Foundation to develop a dengue-resistant mosquito; his group is working on malaria-resistant counterparts as well. “It's very interesting to think we're really targeting a much smaller part of the population than we thought,” he says.

    But Vernick goes a step further: Instead of introducing new genes, why not try to wipe out the minority susceptibility alleles? One possible strategy, he says, would use insect-devouring fungi that two studies identified as potential weapons against malaria last year (Science, 10 June 2005, p. 1531). The work suggested that the fungi preferentially kill Plasmodium-infected mosquitoes. If that's true, spraying with the fungi might drive susceptibility genes out of existence, Vernick says.

    Willem Takken of Wageningen University in the Netherlands, who co-authored one of the papers, says that “it may be a bit utopian, but it's a very interesting idea.”

  8. BIOMEDICAL RESEARCH

    Bone Disease Gene Finally Found

    1. Jennifer Couzin

    Before dozens of people in an auditorium at the University of Pennsylvania, announcing the biggest discovery of his career, Fred Kaplan fought back tears. His 15-year search for the gene behind a rare and horrifying bone disease had ended, fingering a single DNA base as the culprit and offering hope to the small number of people afflicted with the often fatal illness. Three days before, Kaplan, an orthopedic surgeon, had privately shared the news that the gene search was over with some members of the International Fibrodysplasia Ossificans Progressiva (FOP) Association. “We were all crying,” he says.

    Trapped.

    Extra bone blankets the torso of this 12-year-old who has a genetic disease in which sufferers grow a “second skeleton.”

    CREDITS: COURTESY OF K. VERNICK; E. SHORE AND F. KAPLAN/UNIVERSITY OF PENNSYLVANIA SCHOOL OF MEDICINE

    The relentless hunt for the FOP gene had tightly bound Kaplan and a small band of researchers to FOP families from places as far away as the Amazon rainforest, rural Georgia, Bavaria, and South Korea. Thanks to fundraising efforts such as barn dances in Scotland and sales of barbecued chickens in California, these families' communities have collected about 75% of the money used in FOP research.

    In people with FOP—2500 or so are thought to be living with the disease—muscle and connective tissue gradually turn to apparently healthy bone, freezing the neck, spine, hips, and even jaw into place and trapping patients inside a “second skeleton.” The newly discovered gene mutation, described this week online in Nature Genetics, not only has potential therapeutic implications for the currently untreatable disorder, but it may also reveal novel avenues for harnessing the tragic talent of FOP patients to produce prolific amounts of bone. “We always need hard tissue,” says Patrick Warnke of the University of Kiel in Germany, who is exploring ways to grow bone and performs facial reconstruction on patients who have lost bone to cancer or trauma. The FOP gene defect, he says, could “show us the way to induce bone growth.”

    The FOP defect appears in a gene, called ACVR1, that lies along a well-known pathway that controls the formation of bone and cartilage. Kaplan, University of Pennsylvania geneticist Eileen Shore, and their colleagues discovered in the 1990s that FOP patients had defects in this pathway, but they couldn't identify the underlying gene mutation until recently. The mutant form of ACVR1 found in people with FOP produces a protein that has an altered amino acid sequence and is possibly overactive; the normal ACVR1 protein seems to signal cells to boost production of a so-called bone morphogenic protein that spurs bone growth and to clamp down on other proteins that inhibit bone proliferation.

    The gene, says Michael Longaker, a craniofacial surgeon at Stanford University in California, offers “an accelerator and a brake” to bone growth. In people needing new bone, boosting ACVR1's expression locally could be a way to induce their bodies to grow some on their own. In FOP patients, blocking the receptor with a drug or perhaps a targeted therapy such as RNA interference could retard or prevent the condition's uncontrolled bone growth.

    The search for the FOP gene was marred by wrong turns. In 2000, Kaplan's team published a paper linking FOP to chromosome 4, then failed to find the same pattern in additional patients. (ACVR1 is on chromosome 2.) The previous year, a French group claimed to have identified a candidate gene, but its results weren't replicated.

    Faced with an uncommon disease in which families with more than one FOP member are vanishingly rare—few sufferers have children, and most develop the disease because of a random mutation—Kaplan issued an “all points bulletin” to doctors worldwide to send families his way. In the end, just five families with multiple members with FOP provided the critical DNA needed to identify the ACVR1 mutation. The single-nucleotide variation identified in them has been found in all 50 FOP patients tested and is absent from all of 159 controls.

    “That it's so specific is pretty amazing,” says Harvard University geneticist William Gelbart. He hopes that an FOP mouse model can now be created, allowing for deeper study of the disease and potentially drug development, something Kaplan, Shore, and others are already working on.

    Kaplan acknowledges that an FOP treatment may still be many years away. For now, his overriding emotion, after such a prolonged gene search, is relief.

  9. MICROBIOLOGY

    Environmentally Sensitive Protein Proves Key to Making Yeast Pathogenic

    1. Elizabeth Pennisi

    A handful of common soil molds are the Jekylls and Hydes of the fungal kingdom: Human body heat triggers their transformation from a benign fungus to a pathogenic yeast. On page 583, Bruce Klein, an infectious diseases physician at the University of Wisconsin, Madison, and his colleagues reveal a single gene that sets in motion this pernicious makeover.

    Good guy, bad guy.

    Body heat can turn some soil molds (top) into pathogenic yeast (bottom).

    CREDITS (TOP TO BOTTOM): PROVIDED BY B. KLEIN; REPRODUCED FROM THE J. OF EXP. MED. 189, 8 (1999), BY COPYRIGHT PERMISSION OF THE ROCKEFELLER UNIVERSITY PRESS

    “These fungal pathogens have been extremely difficult to study,” says Joseph Heitman, a molecular medical mycologist at Duke University in Durham, North Carolina. “This is a terrific paper.” And because the human version of this triggering gene is not functional, it could be a useful target for drugs to treat these infections, says Klein.

    Six species of soil molds are known to undergo the Jekyll-to-Hyde transformation, causing coughs, fevers, and other symptoms when inhaled. The organisms change from a form that reproduces through spores to one that reproduces by budding—a much more efficient process in humans.

    Researchers already knew that a fungal gene called BAD1 helps the fungus stick to the lung's lining, move into the lung cells, and avoid destruction by the immune system. But no one could figure out what turned on this gene. “This is one of the big questions that has captured my imagination and that of this field for many years,” says Klein.

    To answer it, Klein's graduate student Julie Nemecek made 15,000 mutants of Blastomyces dermatitidis, one of the Jekyll-and-Hyde fungi. She exploited a bacterium previously used in plant genetic engineering to insert gene-disrupting pieces of DNA at random places in the fungus's genome. She applied this technique to B. dermatitidis strains that had already been engineered to turn blue when the BAD1 gene was fully activated and white when it wasn't.

    From the 15,000 mutants, Nemecek identified seven white cultures, one of which had almost no signs of BAD1 activity. The shape of that fungus, as well as the composition and structure of its cell walls, were not very yeast-like, and the number of infectious spores the defective fungus produced in artificially warmed conditions shrank by 90%.

    Nemecek then identified the gene that was disrupted in this mutant strain. She and Klein concluded that, based on its DNA sequence, the gene codes for a protein called histidine kinase. This enzyme and its relatives help organisms sense changes in their environments, including temperature shifts. They are ancient, existing throughout the tree of life.

    The researchers named the gene DRK1 for dimorphism-regulating histidine kinase. When Nemecek specifically knocked out this gene in B. dermatitidis, or dampened its activity using a method called RNA interference (RNAi), the fungus produced few to no spores. And when she used RNAi on another Jekyll-and-Hyde fungus, the mold only poorly converted into yeast when warmed, suggesting that DRK1 might be key in all six pathogenic species. “This is an excellent piece of work in finding the key regulator of fungal dimorphism,” says K. J. Kwon-Chung, a molecular mycologist at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, which funded the work.

    Marcel Wüthrich, an immunologist at the University of Wisconsin Medical School in Madison, also exposed mice to spores with defective DRK1. The lung infections were much less severe than when the mice were infected with unaltered molds.

    Other researchers have discovered that histidine kinases exist in bacterial pathogens, suggesting that they control virulence in many microbes. If so, these enzymes may “serve as a global target for drug discovery,” says Richard Calderone, a medical mycologist at Georgetown University in Washington, D.C.

  10. CELL BIOLOGY

    Picking Up the Pieces After Hwang

    1. Gretchen Vogel*
    1. With reporting by Dennis Normile.

    Several groups around the world are trying to do what Woo Suk Hwang fraudulently claimed to have done

    Best yet.

    Miodrag Stojkovic and Alison Murdoch and their colleagues generated this cloned human blastocyst but were not able to derive ES cells from it.

    CREDIT: MIODRAG STOJKOVIC

    A year ago, it seemed so easy. In May 2005, Woo Suk Hwang and his colleagues told the world that they could make embryonic stem (ES) cells from cloned human embryos with an efficiency that astounded—and thrilled—their colleagues. In roughly one out of every 12 tries, the South Korean team reported, they could produce ES cell lines that were a genetic match to patients. Scientists hoped to use such cells to probe the genetic triggers of diseases such as diabetes and amyotrophic lateral sclerosis (ALS). Some dreamed of using them as the raw material for developing new tissues and cells that could treat previously incurable maladies.

    A few months ago, those claims famously unraveled. It is now clear that Hwang's team does not have any ES cell lines created from patients. It is also clear that the group didn't fail for lack of trying: The team apparently used more than 2200 donated human oocytes in their experiments—more than five times the number they claimed in their papers (Science, 10 February, p. 754). The meltdown dashed the hopes of researchers and patients around the world, leaving many wondering whether cloning might be too difficult after all.

    But as the shock of the scandal wears off, a handful of groups around the world are trying to do what Hwang and his group apparently couldn't. At least three groups in the United States, three in Europe, and one in China say they are preparing to start efforts to derive ES cells from cloned human embryos. In attempting this feat, they all face two substantial hurdles: a limited supply of human oocytes and a lack of data on how to use them most efficiently.

    After the fall.

    Woo Suk Hwang and his colleagues do not have the stem cells they claimed to have made from cloned human blastocysts.

    CREDIT: CHUNG SUNG-JUN/GETTY IMAGES

    Most researchers agree that they have to discount nearly everything they thought they had learned from Hwang, but they also know that Hwang's techniques did achieve some successes. The lab does have one confirmed—and unprecedented—claim: It cloned a dog. And investigators at Seoul National University concluded that the lab did produce cloned human blastocysts, or week-old embryos, in about one out of every 10 attempts. But the team apparently failed to derive viable ES cells from those cloned embryos. It is not clear whether the fault lies with low-quality embryos generated by cloning or with the techniques the team used to try to derive stem cells.

    A collaboration at Harvard Stem Cell Institute is set to find out. Even before Hwang's claims fell apart, researchers there were planning to try their hands at deriving human ES cells through a process known as somatic cell nuclear transfer (SCNT). A successful derivation involves two distinct steps, both of which require considerable skill. In SCNT, scientists remove the nuclear DNA from an oocyte, attempting to inflict as little damage on the cell as possible. They then fuse the enucleated oocyte with a skin cell or other somatic cell. The oocyte provides signals that reprogram the somatic cell DNA and enable it to direct the development of an early-stage embryo. To make ES cell lines, scientists next isolate the group of cells called the inner cell mass from week-old cloned embryos and coax them to grow in culture dishes.

    Now, almost 2 years after they started, Douglas Melton and Kevin Eggan of Harvard University and George Daley of Harvard Medical School in Boston have accumulated nearly all the approvals and permissions they need to start accepting oocyte donations. The process has involved at least five ethics committees and Institutional Review Boards, which must review the ethical safeguards governing donations of oocytes and also of somatic cells from patients. Because current government rules prohibit the use of federal money to derive new human ES cell lines, the Harvard team is funding this effort—including the facilities—with money from the Stowers Medical Institute in Cambridge, Massachusetts, the Juvenile Diabetes Research Foundation International in New York City, and other private donors.

    The Harvard team wants to create cell lines from patients with diabetes and ALS, which they hope will help researchers understand the genetic and molecular processes that drive these diseases. The group will rely on so-called compassionate donors, women who are willing to donate oocytes specifically for research. Eggan and his colleagues hope that using fresher, healthier oocytes than those left over after in vitro fertilization (IVF) procedures will increase the chances of success. Hwang and his colleagues reported that freshly harvested oocytes from women younger than 30 were significantly more efficient than oocytes from women 30 or older. That claim is plausible in light of well-established fertility statistics, say researchers, but can't be completely trusted. Harvard researchers have said they hope to attract women younger than 30 as donors.

    Two other U.S. groups, in New York City and San Francisco, say that for their first efforts they will rely on excess oocytes from women undergoing fertility treatments. One of the team leaders, fertility expert and developmental biologist Renee Reijo-Pera of the University of California, San Francisco (UCSF), had planned to send students to Seoul to learn Hwang's techniques. With those plans scotched, the team has a protocol under review at the university that would use oocytes collected for IVF treatments but which failed to fertilize in the culture dish. Such oocytes are likely to be lower quality, but they would otherwise be discarded, so the ethical questions surrounding their use are less troubling. “We are still at a stage where the technology [for human SCNT] has not been properly developed,” says Arnold Kriegstein, director of UCSF's stem cell biology program. Until researchers know more about which techniques might work best, he says, they will avoid treating volunteers with the ovary-stimulating drugs required for egg donation, which can cause serious complications. The work is being funded by private donations.

    ILLUSTRATION: P. HUEY/SCIENCE

    The lab of developmental biologist Lorenz Studer at Memorial Sloan-Kettering Cancer Center in New York City was one of a handful that was working with several cell lines from Hwang's lab when the scandal broke. Investigators later determined that the lines were most likely not created through cloning but arose either from early parthenogenetic development, in which an unfertilized oocyte begins dividing, or from IVF-derived embryos. Studer, who says he has not heard from Hwang since fraud allegations were first raised, will now collaborate with colleagues at Rockefeller University and Weill Cornell Medical Center. The three institutions received a $50 million grant from the Starr Foundation in New York City last year to focus on stem cell research, part of which will fund nuclear transfer to create cell lines from ALS and Parkinson's patients.

    Studer cautions, however, that successful cloning attempts may be few and far between. “I don't doubt that you can do it, but the efficiency might be so low that you couldn't do it on a practical level,” says Studer, who hopes to use ES cell lines for both basic research and drug screening. “It looks like the most likely efficiency is 10 times lower than [Hwang and his team] claimed” last year—which might mean a success rate of one out of more than 200 tries.

    In Europe, at least three groups have said publicly that they hope to get human cloning working in their labs. All are being funded at least in part by government grants. A group led by Ian Wilmut of the University of Edinburgh and Christopher Shaw of King's College London received a license from Britain's Human Fertilisation and Embryo Authority in February 2005 to conduct human nuclear transfer experiments, but Wilmut says the scandal has prompted them to rethink their plans: “It was necessary to spend some time unlearning some things that we thought we had learned from Hwang's research.” The researchers are now preparing a new application for permission and funding for a slightly different approach to creating ES cell lines from Parkinson's and ALS patients, he says. The researchers may attempt to use rabbit instead of human oocytes, he says. (Researchers in China have reported deriving human ES cell lines from embryos generated through SCNT using rabbit oocytes.)

    After the Hwang debacle, researchers at the University of Newcastle upon Tyne in the United Kingdom hold the distinction of having published the only paper on human cloning that has not been discredited. Alison Murdoch, Miodrag Stojkovic, and their colleagues reported in 2005 in Reproductive Biomedicine Online that they were able to create a single human blastocyst, although they could not derive ES cells from it. Murdoch declines to discuss recent progress until the team is ready to publish another paper.

    Stojkovic has since moved to Valencia, Spain, where he is deputy director at the Prince Felipe Research Centre, a $180 million facility funded by local and national governments and private sources. In March, the Spanish government legalized human nuclear transfer experiments; Stojkovic is now seeking approval from a national ethics committee. He says his team could start working with human material as early as this summer.

    Stojkovic says he will obtain oocytes from a large fertility hospital in Valencia that manages 3000 cycles of fertility treatment per year. But he says he won't bother with leftover oocytes that failed to fertilize in the lab: “From what I have seen, the potential [of fail-to-fertilize oocytes] is equal to zero. We need fresh human eggs. What you get left over from the IVF clinic is not viable.” In fact, he says, every minute counts. In the paper describing the cloned blastocyst, he and his colleagues reported that oocytes were most effective if they were enucleated within an hour after collection. He says he hopes to find women who produce significantly more oocytes than they need or who would be willing to donate some of their oocytes in exchange for a discount on the cost of their fertility treatment.

    Finally, a team at the Chinese Academy of Sciences' Shanghai Institutes for Biological Sciences is now seeking approval for human cloning. “Hwang's work was fake, but someone has to do the real thing,” says Guotong Xu, deputy director of the Institute of Health Sciences there. The stumbling block is not likely to be approval, says Xu, but money, as no one knows whether China's funding agencies consider human SCNT efforts worthwhile.

    As the field attempts to rebuild post-Hwang, Studer hopes the groups will behave like informal collaborators rather than rivals. “It is important that we all stay in contact … so we know what we are each trying to do,” he says. Oocytes are scarce enough that teams should try to waste as few as possible—and should avoid directly duplicating each other's work, he says.

    Stojkovic says he is optimistic that someone will soon succeed where Hwang and his colleagues failed. “I have no doubt that soon someone will have cloned human stem cells,” he says. “I don't know any technical, biological, or ethical reasons we should not continue.”

  11. BIOMEDICAL RESEARCH

    Fragile X's Unwelcome Relative

    1. Greg Miller

    By studying the grandfathers of children with Fragile X syndrome, scientists have found a surprisingly common neurological disorder that may be due to abnormal RNA

    Checkup time.

    Paul and Randi Hagerman examine an FXTAS patient who is the grandfather of a child with Fragile X.

    CREDIT: JOHN LEE/GETTY IMAGES

    Randi Hagerman may be the only pediatrician to discover a disease that strikes in old age. Hagerman specializes in treating children with Fragile X syndrome, the most common inherited form of mental retardation. Several years ago, she began to notice something odd when she chatted with her patients' parents. “Typically, the moms would bring the children in to see Randi, and in the course of the discussion, the moms would say, ‘I'm concerned about my father. He's falling down a lot,'” says molecular biologist Paul Hagerman, Randi's husband and research collaborator. “This was a pattern she would hear over and over.”

    At first, the Hagermans suspected this was nothing more than a few isolated cases of ataxia, or coordination problems. That changed in 2000, when Randi presented neurological workups of a small group of her patients' grandfathers at a Fragile X conference for researchers and parents. At the end of her talk, she asked if anyone in the audience had seen similar problems. “Of the mothers in the room, I would say a third of the hands went up,” Randi says. “It was an epiphany of sorts,” Paul recalls.

    Follow-up studies by the Hagermans, now at the University of California (UC), Davis, and collaborators have recently documented a suite of symptoms that strike the relatives—most often the maternal grandfathers—of children with Fragile X. These men are typically healthy early in life and have average to above-average IQ's. But in their 50s and 60s, many begin to experience tremors and movement difficulties that grow progressively worse. Studies have turned up cognitive and psychiatric problems in these men as well. The symptoms are far more disabling than the general decline people experience with age, and they can lead to death.

    The newly identified disorder, called Fragile X-associated tremor/ataxia syndrome (FXTAS), may turn out to be one of the most common inherited forms of neurodegenerative disease. Work by the Hagermans and others has linked FXTAS to the same gene responsible for Fragile X—even though the two disorders are drastically different. Researchers are now studying postmortem brain tissue from FXTAS patients and creating genetically altered fruit flies and mice in hopes of unraveling the disorder's underlying biology. Physicians are also documenting the clinical progression of FXTAS, work that should help neurologists avoid misdiagnosing it—as happens often.

    “At first, no one was quite sure this was real,” says Stephen Warren, a geneticist at Emory University in Atlanta, Georgia, and a co-discoverer of the genetic mutation that causes Fragile X. Doctors had always told relatives of children with Fragile X syndrome that they had no reason to expect health problems themselves and that their only risk was passing on a bad gene to the next generation. Now, says Warren, it's clear that this counsel was misguided.

    A puzzling premutation

    Fragile X syndrome earned its name from the brittle appearance of the X chromosome in people with the disorder: Under a microscope, part of the chromosome looks as if it's dangling by a thread. In 1991, researchers identified a mutated gene that resides in that part of the chromosome. A genetic stutter gives the gene, called FMR1, 200 or more repeats of the same sequence of three nucleotides: a cytosine followed by two guanines, or CGG. People without Fragile X have about 30 CGG repeats in FMR1, but 200-plus repeats disables the gene, and its protein, called FMRP, doesn't get made. How the lack of FMRP causes mental retardation and other Fragile X symptoms isn't clear, but researchers have recently gotten excited about a theory linking the deficit to aberrations of neural plasticity (see sidebar).

    In some ways, the inheritance pattern of Fragile X sticks to the script every student learns in Genetics 101. Because a boy's X chromosome always comes from his mother, he can only get a bad FMR1 gene from mom. And because they have only one X chromosome, boys who inherit the Fragile X mutation have no other way to make FMRP. But girls are complicated. Despite having a backup copy of FMR1 on their second X chromosome, girls can also develop Fragile X, although they tend to have less mental retardation.

    Another puzzle about the genetics is that most mothers of Fragile X sons have fewer than 200 CGG repeats themselves. Instead, they carry a “premutation” with an intermediate number of repeats ranging from 55 to 200. Through some still-mysterious process, the number of repeats expands into the full mutation that causes Fragile X when passed from mother to offspring. Men can also carry a premutation and pass it on to their daughters. (Only daughters inherit dad's X chromosome.)

    Back in 1999, when Randi Hagerman started growing concerned about the maternal grandfathers of her patients, she consulted neurologist Maureen Leehey, a movement specialist at the University of Colorado Medical Center in Denver, where the Hagermans worked at the time. Several of the men had been told they had Parkinson's disease, which involves degeneration of the basal ganglia, a brain region that helps execute movements. But Leehey's neurological tests pointed to problems in a different brain region. The men did poorly, for example, on a test called the tandem gait test—the toe-to-heel walk police use to assess the sobriety of suspected drunk drivers. Parkinson's patients do surprisingly well on this test, Leehey says, but the grandfathers could barely stand with one foot in front of the other, let alone walk in a straight line. That suggested a problem in the cerebellum, a structure at the back of the brain that's important for balance and coordination.

    Subsequent brain scan studies have confirmed this hunch, revealing shrinkage in the middle cerebellar peduncle, a major communication link between the cerebellum and brain stem. These studies have also found signs throughout the brain of degenerated white matter, the axons carrying signals from neuron to neuron.

    What could cause axons to wither? The FMR1 gene isn't silenced in FXTAS patients as it is in people with Fragile X; in fact, levels of the gene's product, FMRP, appear to be nearly normal. That casts suspicion on the mRNA that translates the gene's instructions into protein, says Paul Hagerman. In people with the premutation, FMR1 mRNA bears an unusually high number of CGG repeats just as the gene itself does. Unexpectedly, however, people with the premutation make five to 10 times more FMR1 mRNA than do those without it, Hagerman has found. “It's a puzzle,” he says. “You'd expect it to go down, not up.”

    In a 2002 paper in Brain, the Hagermans and colleagues reported that the brains of four men who died with FXTAS were riddled with tiny blobs of protein and other material. These “inclusions” clustered inside the nuclei of neurons and astrocytes, a type of support cell, and contained high concentrations of FMR1 mRNA. The team has now analyzed a total of 11 brains from FXTAS patients and found that those patients who had more CGG repeats in FMR1 had more inclusions and died at a younger age than did men with fewer repeats. The findings appeared in the January issue of Brain.

    In a second study reported in the same issue, the Hagermans' team identified more than 20 proteins inside the inclusions. One, lamin A/C, is especially interesting, says Paul Hagerman. Lamin A/C is a filamentlike protein that among other duties supports the membrane forming the nucleus of a cell. Hagerman suspects that the CGG repeats make the FMR1 mRNA an unusually attractive binding target for various proteins, including lamin A/C. According to this theory, the mRNA sops up the proteins, preventing them from doing their usual chores inside the cell.

    Signs of trouble.

    An MRI scan (top) reveals degeneration characteristic of FXTAS. In postmortem tissue (bottom), protein inclusions in neurons (dark arrow) and astrocytes (open arrow) are hallmarks of the disease.

    CREDITS (TOP TO BOTTOM): P. J. HAGERMAN; COURTESY OF C. GRECO/UC DAVIS

    Indeed, adding FMR1 mRNA with extra CGG repeats to cultured human neural cells disrupts lamin, Hagerman and colleagues reported in the 1 December 2005 issue of Human Molecular Genetics. “Normally, you see a beautiful ring around the nuclear membrane when you stain for lamin,” Hagerman says. “But when you express the repeats, the ring breaks down and just forms clumps.” Hagerman says it's too early to say how lamin A/C disruptions might cause axon degeneration, but he notes that lamin irregularities have been implicated in another neurodegenerative disorder, Charcot-Marie-Tooth disease.

    Other researchers agree that the sticky mRNA scenario is plausible. Many see a parallel with an inherited muscle disorder called myotonic dystrophy. In the most common form, the problem stems from a mutant gene whose mRNA bears abnormal repetition of the nucleotide sequence CTG. Various proteins glom onto the mRNA's repeat region and neglect their usual duties, causing the cells to malfunction. Although many inherited disorders are caused by a mutation that silences a gene (as in Fragile X) or results in a malformed, toxic protein (as in Huntington's disease), myotonic dystrophy is the only disorder known to be caused by abnormal RNA.

    “The concept of RNA toxicity is really just emerging,” says Emory geneticist Peng Jin. Like the Hagermans, Jin suspects that such toxicity is the root cause of FXTAS. In collaboration with Warren and others, he published a paper in Neuron in 2003 showing that expanded CGG repeats in FMR1 mRNA causes neurodegeneration in fruit flies. The flies also had inclusions in brain cells similar to those seen in FXTAS patients.

    At the same time, researchers have begun studying the effects of FMR1 premutations in animals with nervous systems more closely resembling our own. Last year, Ben Oostra and colleagues at Erasmus University in Rotterdam, the Netherlands, described FXTAS-like symptoms in male mice with 98 CGG repeats in the gene. “If you look at the mice when they're young, there's no difference” between the mutants and their normal brethren, says Oostra. But by 1 year—middle age for a mouse—the mice with the premutation develop symptoms of ataxia, Oostra says. The Dutch researchers also reported in the 30 July 2005 issue of Behavioral Brain Research that these mice become unusually skittish and have memory deficits that grow worse with age—both features that have been described in people with FXTAS.

    Missed diagnosis

    Physicians are still clarifying the symptoms of FXTAS in people. Recent studies have found that memory and cognitive problems often follow the ataxia and tremor, says Randi Hagerman. Some patients act as if they have frontosubcortical dementia, she and colleagues reported in the January issue of the Journal of Clinical Psychiatry. This type of dementia is characterized by difficulty controlling mental processes, and patients often have trouble formulating plans, focusing their attention, or knowing what's appropriate behavior. “We had one guy [with FXTAS] whose family told us when they went out for dinner, he went to the bathroom and came back with the toilet seat on his head as a joke,” Hagerman says.

    A three-center study, led by Paul Hagerman at UC Davis, Leehey in Denver, and Elizabeth Berry-Kravis at Rush University Medical College in Chicago, Illinois, will help nail down the symptoms of the disorder and describe how it progresses. A major goal, says Berry-Kravis, is to determine whether the number of CGG repeats predicts the severity and type of symptoms.

    Shaky hands.

    Difficulty drawing and writing is one of the first signs of FXTAS.

    CREDIT: ELIZABETH BERRY-KRAVIS AND ALLISON SUMIS/RUSH UNIVERSITY MEDICAL CENTER

    For men with the premutation, the prevalence of FXTAS increases sharply with age, from 17% of those in their 50s to 38% of those in their 60s to 75% of those 80 or older, the Hagermans and others reported in the Journal of the American Medical Association (JAMA) in 2004. The researchers estimated that the disorder will strike one in 3000 men in the general population. (FXTAS appears to be very rare among women, although women with the premutation are susceptible to premature menopause for reasons that aren't understood.) If these calculations hold, FXTAS would be one of the most common neurodegenerative disorders linked to a specific gene, says Berry-Kravis, one of the authors of the JAMA study. Huntington's disease, which has been considered relatively common for this type of disorder, only strikes about one in 10,000 people, for example. Other disorders that have a genetic component but aren't tied to a single gene are far more common. Parkinson's disease falls into this category and affects about one in 100 people.

    Misdiagnosing FXTAS as Parkinson's disease or another illness can lead to treatments that are futile or worse, notes Paul Hagerman. “I know of four cases where people had neurosurgery to implant shunts,” he says. The patients were diagnosed with hydrocephaly because their brains had atrophied, making the fluid-filled ventricles deep in the brain look abnormally large.

    The other reason patients need to know if they have FXTAS is the implications for genetic counseling, says Randi Hagerman. As awareness of FXTAS has grown, neurologists have begun to identify the disorder in men whose families include no one with Fragile X syndrome, she says. Some of these men have daughters who may be thinking about starting families, Hagerman notes, and the pattern of inheritance means that all these women carry the premutation: “They didn't know they were carriers, and that's very important information for them.”

  12. BIOMEDICAL RESEARCH

    A Fix for Fragile X Syndrome?

    1. Greg Miller

    The cognitive and behavioral problems associated with Fragile X syndrome would seem to be irreversible, because they're caused by a genetic glitch that derails the development of the nervous system. Yet much to their surprise, some researchers say that many of these problems might be fixable with drugs. Within a year, they predict, clinical trials will be under way to test compounds that target a family of receptors believed to play a critical role in symptoms of the inherited disorder. “I've been working on Fragile X for 25 years, and I never thought I'd be working on a drug,” says Stephen Warren, a geneticist at Emory University in Atlanta, Georgia.

    The drugs Warren and others envision would target the so-called metabotropic glutamate receptor (mGluR) that sits on the surface of neurons. The idea that mGluRs might be important actors in Fragile X arose from a chance meeting several years ago between Warren and Mark Bear, a neuroscientist now at the Massachusetts Institute of Technology in Cambridge.

    At a gathering of Howard Hughes Medical Institute investigators, Bear had described recent work suggesting that mGluRs are crucial for weakening synaptic connections between neurons in the hippocampus, a brain region involved in learning and memory. Such weakening, called long-term depression (LTD), is an important form of neural plasticity during brain development and may underlie changes in neural connectivity that support learning later in life. Bear's lab had discovered that LTD requires activation of mGluRs in order to translate crucial mRNA molecules floating near synapses into proteins.

    Warren, who'd been studying FMRP, the protein that's missing in Fragile X, happened to sit next to Bear after the mGluR talk and introduced himself. Warren's team had found that FMRP suppresses the kind of protein synthesis that Bear had discovered to be essential for LTD. “We began an animated conversation,” Bear says. By the end of it, Warren had agreed to send Bear some Fragile X mice, which have a mutation that mimics that in people with the syndrome.

    Warren, Bear, and colleagues reported in 2002 that these mice have enhanced LTD compared to normal mice. This propensity to weaken synapses could slow brain maturation and contribute to the developmental and cognitive problems seen in people with Fragile X, Bear and Warren later argued in an article published in 2004 in Trends in Neuroscience. Based on this and other evidence, the authors proposed that drugs that block mGluRs could mitigate many symptoms of Fragile X by performing the job normally done by FMRP: putting a check on mGluR-mediated protein synthesis.

    Tests with such compounds in fly and mouse models of Fragile X have lent support for that suggestion. Flies missing the gene that encodes FMRP have altered courtship behavior, impaired learning and memory, and altered anatomy in a brain structure involved in learning—all of which can be reversed with a compound that blocks mGluRs, a team led by Thomas Jongens at the University of Pennsylvania reported in the 3 March 2005 issue of Neuron.

    Blockers of mGluRs also reverse impairments in Fragile X mice, at least in some experiments, says Ben Oostra of Erasmus University in Rotterdam, the Netherlands. Oostra suspects, however, that mGluR blockers won't alleviate all Fragile X symptoms. “I am optimistic that some defects like epilepsy and autistic behavior and maybe hyperactivity might benefit, but I am more pessimistic about other parts of the phenotype of Fragile X,” he says.

    Bear and Warren have each started a company to investigate candidate drugs. Bear is testing mGluR blockers under license from Merck in animals, whereas Warren is screening compounds that may interfere with related cell signaling pathways. “We're doing animal toxicity studies now to ensure they're safe,” says Bear. “So far they look very safe.” He hopes to soon secure permission for a clinical trial.

  13. ALICE DAUTRY PROFILE

    After the Storm, New Pasteur Chief Treads Softly

    1. Martin Enserink

    Following a year of chaos and revolt, the new Pasteur Institute president aims to steady nerves before she continues the path of reforms

    PARIS—After 6 months in the job, Alice Dautry has already proved her mettle in one respect: The Pasteur Institute is working again. The lab had been paralyzed with dissension when Dautry, 55, was appointed president in September 2005. Over a tumultuous year, the staff had revolted against a controversial plan to move several research units to a suburb. Many also objected to what they called the aggressive management style of Dautry's predecessor Philippe Kourilsky. The resulting fights had poisoned the atmosphere and stifled research. In January 2005, the entire board of directors stepped down in an attempt to solve the crisis. Five months later, after a new board had been elected, Kourilsky was forced to leave.

    Guarding the heritage.

    Alice Dautry, who took the helm of the Pasteur Institute in September, wants to strengthen its efforts in virology.

    CREDIT: STEPHANE DE SAKUTIN/AFP/GETTY IMAGES

    Pasteur scientists say Dautry's personal style—she comes across as likable, informal, and modest—has helped heal wounds and restore a sense of normality. But now that the honeymoon is over, Dautry is facing the same challenges as her predecessor: keeping Pasteur at the top of the global research league, promoting excellence despite a fragile budget, recruiting talent at modest salaries to facilities that are now quite aged, and countering the general malaise that afflicts French science. And her solutions may turn out to be not radically different from what Kourilsky had in mind. For example, Dautry doesn't even rule out the possibility of a new relocation plan. But her style is unquestionably more diplomatic.

    Dautry has a doctorate in physics from Paris-Sud University and a master's in molecular biology from Stony Brook University in New York. She was lured to Pasteur by the famed biologist, Nobel laureate, and World War II resistance fighter Jacques Monod in 1975. “I was very young and very, very impressed,” she says. She started her own group in 1984 after a 2-year stint at the Massachusetts Institute of Technology and has headed a 12-person unit called Biology of Cell Interactions since 1992. She is the first woman at Pasteur's helm, although she says the director's gender is irrelevant.

    Despite the recent mayhem, the lab Dautry inherits is in better shape now than it was 5 years ago, many Pasteur scientists agree. Kourilsky tried to make the institute more attractive to young scientists by offering them small research groups for 5 years, strengthened evaluations based on merit, sought to create new international collaborations, and tried to increase revenues from patents to boost a straining budget. Whatever his management flaws, continuing Kourilsky's policies is “extremely important,” an external panel wrote in a May 2005 letter to the newly elected president of the board of directors, François Ailleret.

    Dautry declined to comment directly on the letter, but in an interview with Science, she emphasized many of the themes Kourilsky promoted. She says she wants to lure more young scientists and give them a stronger voice in the institute; like Kourilsky, she wants to expand collaborations abroad; and a certain resentment against commerce at Pasteur notwithstanding, she also wants to coach Pasteur staff on the importance of patents. But so far, she has moved cautiously. When she introduced herself to French journalists during a press conference in February, she announced some shifts in emphasis but no grand plans.

    Close community

    In contrast to Kourilsky, who envisioned continued rapid growth, Dautry isn't convinced that Pasteur's staff needs to expand much further. With some 1400 scientists and 1200 support staff, the lab is still a close community. People know each other, and this stimulates collaboration and creativity, she says: “If we do grow much more, we become something else, and we lose some of that synergy.”

    Boosting Pasteur's efforts in virology is necessary, says Dautry, because so many emerging threats—including SARS and avian influenza—are caused by viruses. But any new investments won't be to the detriment of traditional Pasteur strongholds such as parasitology and bacteriology, Dautry says. Nor does she plan to quit topics such as neurobiology and developmental biology, both of which are considered expendable by some in the event of a complete focus on infectious diseases.

    Instead, she says she can strengthen virus research by seeking more outside collaborations and by breaking down the walls within the institute itself. In a recent reorganization, for instance, all virologists were united in a new department, and Pasteur quickly launched a broad research program in response to the outbreak of Chikungunya, a relatively unknown mosquito-borne virus that sickened hundreds of thousands on the French island of La Réunion in the Indian Ocean (Science, 24 February, p. 1085).

    Dautry also has high hopes for collaboration with the 28 Pasteur Institutes around the world, most of them in developing countries. Essentially a holdover from the colonial era, the majority are now independent, and their number is still growing. (The latest, nestled in a former French missionary building in Shanghai, is a 2-year-old collaboration with the Chinese Academy of Sciences. Dautry says another deal may soon be signed.) The mother ship in Paris helps the labs build research capacity and in return gets to study diseases where they happen. And in an age of one emerging disease after another, “it's really a unique opportunity,” says cell biologist and Nobelist Paul Nurse of Rockefeller University in New York City, a member of the external panel who was asked earlier this month by Dautry to help set up a new one.

    The workspace in Paris, meanwhile, remains a sensitive issue. Kourilsky was ultimately undone by his plan to move part of the lab from its beloved Paris campus—where Louis Pasteur is buried, and his home and lab turned into a museum—to a building donated by drug company Pfizer on an industrial site in the southern suburb of Fresnes. The plan, which Kourilsky deemed essential for growth, was dropped when mediator John Skehel, director of Britain's National Institute for Medical Research in London, concluded the move was unnecessary (Science, 25 February 2005, p. 1183).

    Although that ruled out Fresnes, Dautry says she hasn't closed the book on all new locations, provided they can add something that's valuable for research, such as increased collaboration with nearby hospitals, research centers, or technology hubs. The problem with Fresnes, she says, was that “it was just a site to move people to. It wasn't part of a clear project to develop the institute.” The discussion will start anew, “very calmly,” in 6 or 12 months, she says. Meanwhile, Dautry faces challenges on the existing campus: A complex refurbishment requires temporarily shuffling groups between already cramped buildings, and neighbors in Paris's 15th arrondissement have voiced opposition—and could delay—construction of a planned new building.

    So far, Pasteur staff members have given her the benefit of the doubt. “We're in a period of mutual observation. … It's wait and see,” says Elise Caliot, a member of the Workforce Delegates—one of two bodies representing workers at the institute—on behalf of the trade union CGT. A first test of the new relationship will come soon, when collective salary negotiations begin, says Caliot. (The unions are aiming for a raise.) But she approves of the fact that Dautry has opted for a small, three-member management team from within Pasteur that is in frequent dialogue with the work floor. Caliot says that Kourilsky recruited managers from the world of business who didn't fit in with Pasteur's academic culture; Dautry hasn't made that error, she adds.

    Antoine Danchin, who heads the Genomes and Genetics department at Pasteur, says that despite her affable manner, Dautry “may be more authoritarian than one would think. … She knows what she wants to do.” The biggest problem facing her, however, is luring fresh talent at a time when lab budgets are meager and researchers in their late 30s make hardly any more money than Paris Metro drivers. “Her main problem is not going to be within Pasteur,” says Danchin. “It's going to be the crisis in France.”

  14. AGRICULTURE

    New Disease Endangers Florida's Already-Suffering Citrus Trees

    1. Erik Stokstad

    Researchers are mobilizing to stop a wily bacterial marauder spread by invasive insects, but massive losses appear inevitable

    Soured.

    A foreign bacterium deforms citrus such as this pomelo and gives it an acrid taste.

    CREDIT: XIAOAN SUN AND SUSAN HALBERT

    Things are going from bad to worse for citrus growers in Florida, the state that produces most of the oranges, grapefruit, and limes grown in the United States. The $9 billion industry has spent much of the past decade wrestling with an epidemic of canker that cut production by roughly a third. In a long, drawn-out effort to eradicate the wind-borne bacteria, 12.7 million trees—among them 10% of Florida's commercial acreage—have been cut down at a cost of $600 million including compensation. But in January, the U.S. Department of Agriculture (USDA) decided that eradicating canker was a lost cause and halted its efforts.

    Even more dire news arrived last August, when a team of scientists discovered two cases of citrus greening in South Florida. Greening is “probably the worst citrus disease in the world,” says Harold Browning, who directs the University of Florida's Citrus Research and Education Center (CREC) in Lake Alfred. Whereas canker just makes trees less productive and blemishes fruit, greening renders it totally unusable and eventually kills the trees.

    Researchers think it will be impossible to stop the disease from conquering the state, because the pathogen, a bacterium called Candidatus liberibacter, is spread by an introduced insect that has run rampant across Florida. Even just getting a firm grasp of the situation is devilishly tricky: Infected and contagious trees don't show symptoms for several years. “It's commonly widespread before it's discovered,” says plant epidemiologist Timothy Gottwald of USDA in Fort Pierce, Florida. “It's almost below the threshold of detection until it explodes.”

    The goal now is to contain that explosion as much as possible. A nationwide survey of citrus states is under way, and researchers are racing to sequence the genome of the bacterium in hope of developing new tests to detect the microbe. At the same time, research is also aimed at finding ways to help growers manage the disease, such as the most effective way to spray insecticides. A preliminary response plan released last month by USDA and the Florida Department of Agriculture and Consumer Services (FDACS) lays out strategies for keeping nurseries disease-free. But with two major pathogens likely entrenched in Florida—and more looming on the horizon—some researchers say only the distant prospect of citrus trees engineered for resistance may save the industry.

    Worldwide menace

    There's good reason to be concerned about greening. The disease has devastated citrus crops across the world, ravaged by three species of the bacterium. Trees become stunted and lose leaves. Instead of living for decades, they die after just 5 to 8 years. Their fruit can be lopsided, small, and green (hence the name), and they make vile juice. “It tastes like jet fuel mixed with Vicks VapoRub,” says David Hall, an entomologist with USDA in Fort Pierce, Florida. Throughout China and India, the Asian species of C. liberibacter—now present in Florida—has made production economically impossible. The vector is an aphidlike insect called a psyllid. If psyllids are abundant, greening can wipe out a grove in just a few years.

    Florida entomologists first spotted the Asian citrus psyllid (Diaphorina citri) in 1998. It likely arrived on infested plant material and since then has hitchhiked across the state on orange jasmine (Murraya paniculata), an ornamental plant shipped in large quantities by discount stores. Two years ago, USDA and FDACS began conducting limited scouting trips for greening.

    In August, inspectors spotted a pomelo tree that had lost its leaves and had misshapen fruit on a small farm near Florida City, in the southern end of the state. “The alarm bells really started ringing,” Gottwald recalls. After two government labs confirmed the presence of greening, more survey teams were sent out and quickly found the disease as far as 270 kilometers north. “It became clear that this had spread beyond anything we could get our arms around,” Gottwald says. Last month, greening was confirmed in DeSoto County, the 12th county to date. A more detailed statewide survey of incidence and severity will begin next month to look for hot spots. And the USDA has begun coordinating a broader 6-month-long survey of citrus-producing states—California, Arizona, Texas, and Louisiana—looking for both greening and psyllids.

    Accurate surveying is not easy. Detecting early stages of greening—before the fruit is affected—is a major challenge, as the symptoms resemble nutrient deficiency. “It's easy to get fooled,” says plant pathologist Ronald Brlansky of the University of Florida's CREC in Lake Alfred. The current molecular test, based on the polymerase chain reaction (PCR), is reliable for confirming a symptomatic infection, but only when levels of bacterium in the sample are high. It also looks for just two genetic loci, which means the test could be missing new species of the pathogen, says plant pathologist and geneticist Dean Gabriel of the University of Florida (UF), Gainesville. Indeed, several highly symptomatic trees have tested negative for the Asian species by PCR, Gabriel says.

    In quarantine.

    Chinese box oranges are among the plants being inspected for the Asian citrus psyllid (inset) in Florida nurseries, which have suffered steep losses of citrus.

    CREDITS: FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES DIVISION OF PLANT INDUSTRY

    Soon after greening was discovered, USDA gave Gabriel a $117,000 grant to sequence the C. liberibacter genome. Because researchers don't know how to grow the organism in the lab, what would otherwise be a trivial sequencing effort is painstaking work, so Gabriel's group has to rely on infected trees in a biosafety level 3 facility. Gabriel expects to complete the sequencing in the next 6 months.

    The inability to culture the bacterium is a serious problem. Unless researchers can grow the bacterium in petri dishes, they are handicapped in discovering which genes make it so destructive. They also can't screen for antimicrobial compounds in vitro or generate various detection methods such as those that rely on monoclonal antibodies. But culturing the bug is a tall order: “Some of the best labs in the world haven't been able to achieve this,” says Gottwald, who thinks it could require concerted effort by multiple labs and millions of dollars. Brlansky has begun work in this direction with Michael Davis of UF Homestead and plant pathologist John Hartung of USDA in Beltsville, Maryland.

    In the meantime, officials are trying to figure out the best way to manage the disease. Last month, USDA and FDACS released a draft response plan for greening that specifies measures for slowing the spread and preventing it from reaching other states. The major steps include inspecting nursery stock to make sure it's disease-free. Nurseries will be required to grow their citrus in screened greenhouses in approved locations. But exactly how far away nurseries must be isolated from groves is controversial; moving facilities could be an enormous expense for nurseries that are already suffering from major losses due to canker. The regulation has not yet been finalized.

    The answer depends on unknowns such as how far psyllids can fly. USDA's Hall and other researchers are studying the psyllid, trying to learn more about its ecology. In addition to helping set guidance for nurseries, the information could help determine the most effective times and doses for citrus growers to spray insecticides. Experts say biocontrol is unlikely to work well in Florida, in part because parasites hold back the wasps used for biocontrol. “With greening, there really aren't many tools,” says UF's Browning.

    One major question is how big a problem the infected trees of homeowners will be. Although these trees will be sources of bacterium until they die, the state won't require their removal, says Timothy Schubert, a plant pathologist with FDACS, citing “political realities.” His department will try to educate homeowners about the need to quickly destroy sick trees, he says, but such attempts were only marginally effective with canker.

    Another question is whether orange jasmine is a host for greening. If so, there would be concerns that shipments of the plant might have spread greening to other states that already have psyllids, such as Texas. (After the discovery of greening, Florida quarantined citrus and citrus relatives in nurseries.) In Brazil, scientists are convinced that orange jasmine can be infected by their species of the bacterium. Some jasmine tested in the United States contains faint, ambiguous signs of DNA from the Asian species of bacterium that's present in Florida. Researchers at USDA's labs in Fort Detrick, Maryland, are continuing to investigate.

    Even though only 615 trees have been confirmed positive so far, Schubert and others expect the number to rise drastically, with a major impact on the citrus industry. The problem will be compounded by a shortage of healthy trees to replace them, due to the crisis at nurseries. In the long term, says Schubert, “the brightest hope of any semblance of an industry like we have had up till now is genetic engineering.” Gabriel and a few other researchers are working on engineering resistance to canker and other diseases into citrus, but no one has yet figured out how to develop resistance to greening. “That's going to take years,” says Gabriel.

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