Science  05 Aug 2011:
Vol. 333, Issue 6043, pp. 682

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  1. A Feel for Blood

    Vampire bats must consume 70% to 80% of their body weight in blood each night. They bite their prey and lap up the spilt blood. Now scientists have discovered a heat-sensing mechanism that helps the bats target their bites to places where blood flows just under the skin.

    In this week's issue of Nature, neuroscientist David Julius of the University of California, San Francisco, and colleagues report that vampire bats make a truncated version of an ion channel called TRPV1. In other animals, this molecular pore detects painful heat and capsaicin, the compound that gives chili peppers their sting. The short version made by vampire bats has a lower heat threshold, so that it can detect substances—like blood—that are at body temperature. Truncated TRPV1 appears in only nerves that innervate the small heat sensing pits on the bat's face, Julius says. Other nerves have the longer, pain-sensing version.


    “It's really fascinating to know how this works,” says Brock Fenton, a bat biologist at the University of Western Ontario in Canada. The findings are an important clue to how vampire bats' unusual lifestyle evolved, Fenton says.

  2. Lab-Grown Disks May Cure That Aching Back

    Aging or injury can cause the disks that cushion each vertebra in the spine to degenerate, pinching nerves and impeding movement. But degenerating disks may soon be replaceable: A research team has implanted living, biologically based disks into rats' spines and found that they allow for as much movement as native, healthy disks.

    Lawrence Bonassar, a biomedical engineer at Cornell University, and his team created an artificial disk-shaped scaffold with collagen on the outside to provide structural stability and a gel in the center. They added two types of living disk cells from a rat's spine: one to the collagen, and another to the gel. For 2 weeks, they let the cells grow around the scaffold into a living disk, then surgically replaced a spinal disk in a rat's tail with the new implant.

    The bioengineered disk, the researchers reported 1 August in the Proceedings of the National Academy of Sciences, provided as much cushioning space between spinal vertebrae as a typical disk does. Moreover, cells from the implant started growing outward into the rest of the spine, as the cells in a normal disk do. And even after 6 months, the implanted disk showed no signs of wear.

  3. Pat-a-Cake Mountain Building On the Far Side of the Moon

    A slow-motion collision of Earth's young moon with an ill-fated smaller companion moon may explain not only the existence of the highlands on the far side of the moon but also the dark lava seas that create the near side's man in the moon.

    Planetary dynamicists Martin Jutzi of the University of Bern in Switzerland, and Erik Asphaug of the University of California, Santa Cruz, thought the best prospect for a sufficiently slow impacter would be a smaller moon formed from the same splash of impact debris off of Earth that formed our present moon. If the smaller moon were caught in a gravitational balance point just ahead or behind the moon—as earlier calculations suggested could happen—the companion moon would eventually hit the moon at hardly a tenth the speed of the usual impacters.

    In the pair's modeling, such a slow impacter did indeed stick to the moon without forming a crater, like throwing mud against a wall. And the splat of the slow impact also drove magma lingering from the moon's formation to the near side, where its heat could have helped fill giant impact craters with the dark lava that shapes the man in the moon.