Findings

Science  29 Jul 2011:
Vol. 333, Issue 6042, pp. 506
  1. 'Bastard' Mouse Steals Poison-Resistance Gene

    Some house mice in Germany and Spain have acquired resistance against a group of widely used rodent poisons through hybridization with a different species, the Algerian mouse. The finding suggests hybridization may play a more important role in animal evolution than researchers believed.

    Warfarin, a drug used to inhibit a protein called VKOR that is important to blood clotting, has been used as a rodenticide since the 1950s. But over several generations, an accumulation of mutations in the gene for VKOR led to increasingly warfarin-tolerant rodents. While studying these mice, biologist Michael Kohn of Rice University in Houston, Texas, discovered that a German house mouse (Mus musculus domesticus) was carrying a big chunk of DNA from Algerian mice (Mus spretus)—a species known to be naturally resistant to warfarin.

    In Spain, where Mus musculus and Mus spretus coexist, 27 of 29 house mice tested carried a version of the warfarin-resistant Mus spretus VKOR DNA. In Germany, where Mus spretus do not live, 16 of 50 house mice also showed this genetic signature, Kohn and colleagues reported online 21 July in Current Biology.

    “We are looking at two species that are 1.5 million to 3 million years removed,” Kohn says. Even though the two rodents overlap in parts of Africa and Europe, they don't usually interbreed—and if they do, all male offspring and some female offspring are sterile. Yet, “that narrow window of a few fertile females must have been enough to leak DNA,” Kohn says. http://scim.ag/HybridMouse

  2. How Blasts Injure the Brain

    More than 300,000 United States troops may have suffered a traumatic brain injury (TBI) in the current wars in Iraq and Afghanistan—most from blasts from roadside bombs and other explosives (see a series of articles beginning on p. 514).

    To better understand how such blasts injure the brain, Kevin Kit Parker, a Harvard University bioengineer, and colleagues devised a blast simulator for cells, growing rat neurons on a stretchy polymer that could be tugged with a high-precision motor to mimic mechanical forces from an explosion. These “blasts” caused swelling and breakage in the neurons' spindly axons and dendrites. This damage seemed to result from alterations to proteins called integrins, which anchor neurons to the protein scaffold that surrounds them, the researchers reported 22 July in PLoS ONE.

    CREDIT: JACK HOLLINGSWORTH

    A second paper from Parker's group, published 15 July in the Proceedings of the National Academy of Sciences, suggests integrin disruption may also contribute to vasospasm, another harmful process associated with TBI. Simulated blasts flipped a genetic switch in the muscle cells that line blood vessels, making them more likely to contract—and potentially exacerbating a brain injury by starving brain tissue of oxygenated blood.

    Most research on TBI has focused on neuro chemical changes, such as metabolic alterations and ion imbalances inside neurons, says David Hovda, a neuroscientist at the University of California, Los Angeles. The new findings suggest a mechanism that hasn't been considered previously, Hovda says. http://scim.ag/brainblasts

  3. Tall People At Greater Risk For Cancer

    CREDIT: AKKO DATTA/REUTERS/LANDOV

    There's a downside to height: tall people are more likely to develop cancer. A study published online 21 July in The Lancet Oncology finds that this holds in women with many types of cancer. The researchers looked at the incidence of 17 cancer types, from breast cancer to leukemia, over 9 years among 1.3 million women in a U.K. health study. Cancer risk rose 16% with every added 10 centimeters in height. The results agree with previous studies of cancer and height in both men and women. The adult height of European populations has risen 1 centimeter per decade since 1900, and this could have increased cancer incidence by 10% to 15%, the researchers say. Why being taller might make people more vulnerable to cancer is not known, however. One possibility is that the hormones that cause children to grow taller also stimulate the growth of cancer cells.

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