Findings

Science  13 May 2011:
Vol. 332, Issue 6031, pp. 774
  1. Another Blow to Putative Cause Of Chronic Fatigue Syndrome

    An exhaustive hunt for a mouse retrovirus known as XMRV in people who have chronic fatigue syndrome (CFS)—including patients who tested positive for the virus in other labs—has come up dry, further deflating hopes that a cause for this baffling disease has been found. “I'd urge people to move on rather than to keep their hopes hanging on the link between XMRV and CFS,” says Ila Singh, a virologist at the University of Utah in Salt Lake City, who led the new study.

    The link between XMRV and CFS has sparked debate since it was first reported (Science, 23 October 2009, p. 585). Singh's analysis is the latest of several that have failed to find XMRV in CFS patients, but the first to test samples from patients involved in the original study. As Singh and her colleagues reported online 4 May in the Journal of Virology, they used several tests for XMRV, including fishing for viral sequences with the ultrasensitive PCR assay, trying to grow the virus in cell cultures, and scouring the blood for antibodies to viral proteins. All 100 samples, including those from 14 patients from the original study, were negative. http://scim.ag/_XMRV

  2. Ship in Bottle, Meet Rogue Wave in Tub

    CREDIT: RICHARD BEHN, NOAA CORPS/NOAA PHOTO LIBRARY

    Toy boats beware! For the first time, physicists have created a rogue wave in a laboratory tank, supporting the idea that a simplified theory can explain the freakishly tall ship sinkers.

    Researchers have proposed describing anomalous water waves with a simple differential equation called the nonlinear Schrödinger equation. One of its solutions consists of an isolated peak that emerges out of a steady wave train (a so-called sine wave) then fades back into it, just like a rogue wave. Now, mathematician Amin Chabchoub at the Hamburg University of Technology and colleagues have produced that “Peregrine solution” in a 15-meter-by-1.6-meter tank filled with water to a depth of 1 meter. Using a computer-controlled paddle, they generated a sine wave with an amplitude of 1 centimeter. They then briefly increased the size of the paddle's motion to trigger a rogue wave that grows to three times the sine wave's height and moves at half its speed, exactly as predicted by the Peregrine solution, the researchers report in a paper in press at Physical Review Letters.

    Demonstrating the Peregrine solution in water waves is a “big step” toward proving that the nonlinear Schrödinger equation can describe real-world ocean waves, says Al Osborne, a physicist at the University of Turin in Italy. Next up: creating rogue waves in water that's more chaotic. http://scim.ag/_rogue

  3. Vaccine Thwarts SIV in Monkeys

    CREDIT: FOTOSEARCH

    AIDS vaccine research received a much-needed booster shot this week. An experiment published online in Nature, led by immunologist Louis Picker of the Oregon Health & Science University in Beaverton, showed that an unusual approach to outwit SIV (a simian cousin of HIV) protected 12 of 24 vaccinated monkeys from a “challenge” with a particularly virulent strain of that virus. The protected monkeys became infected, but their immune systems drove the virus down to undetectable levels for more than a year. “It's the best result I've seen against the worst SIV known,” says David Watkins of the University of Wisconsin, Madison, who was not involved with the work. “I'm very excited by this approach.”

    The vaccine contains SIV genes stitched into a harmless cytomegalovirus (CMV) vector. AIDS vaccines usually use vectors that quickly die out after delivering the AIDS virus genes, but the CMV stays alive indefinitely and constantly confronts the immune system with the mock version of the enemy. As a result, Picker contends, the immune system stays on high alert and can respond to an attack by the real virus much more quickly. “The whole game changes when you talk about early interception of the virus,” Picker says.

    http://scim.ag/_SIV

  4. Even Robots Can Be Heroes

    CREDIT: EPFL/ALAIN HERZOG

    Evolutionary biologists have struggled to explain self-sacrificing behavior, which seems to defy survival of the fittest. Simulations of “evolving” robots have now confirmed an explanation posed by biologist W. D. Hamilton in the 1960s: We tend to help those who are more closely related to us because they can pass on more of our genes.

    To test Hamilton's idea, scientists need to watch organisms evolve over many generations. So Laurent Keller of the University of Lausanne in Switzerland and his colleagues created an evolutionary computer simulation starring tiny robots (pictured). To simulate mutations, the computer randomly tweaked the connections in the robots' “nervous systems,” making them better or worse at retrieving small discs—a stand-in for food.

    The simulations ran for hundreds of rounds, each time selecting and cloning the best food gatherers and culling the others. Sharing evolved most quickly in more closely related robots, as Hamilton predicted, the researchers reported online 3 May in PLoS Biology.

    Some researchers are leery of drawing conclusions about organisms from virtual robots, but others say the work shows how robust Hamilton's rule is.

    http://scim.ag/robot-heroes

  5. High-Tech Gas Drilling Fouling Drinking Water

    A study, published this week in the Proceedings of the National Academy of Sciences, is the first systematic, peer-reviewed analysis to build a credible link between extraction of natural gas locked deep in shale and the contamination of nearby water wells. The analysis gives few clues, however, to how pervasive such contamination might be.

    Injecting high-pressure fluids into deep shale frees methane.

    CREDIT: ROBERT JACKSON

    The Oscar-nominated documentary film Gasland dramatized the debate over shale gas extraction by showing a homeowner setting fire to well water gushing from a faucet. The supposed culprit was nearby “fracking,” pumping fluids into a wellbore until the shale shatters, releasing the tightly bound gas.

    Duke University environmental scientists sampled well water across 175 kilo meters of far northeast Pennsylvania. Methane was at background levels more than a kilometer from an active gas well. But methane levels shot up closer to fracking operations, in some cases to flammable levels. Chemical and isotopic analyses clinched the case, tying the gas from close-in water wells to the deep shale. The new study will no doubt be on the reading list of a blue-ribbon panel announced last week by Energy Secretary Steven Chu that will recommend ways to improve shale gas fracking.

    http://scim.ag/methane-water

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