Science  27 Sep 2013:
Vol. 341, Issue 6153, pp. 1435

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  1. Naps Nurture Young Brains

    Making memories.

    Naps help kids (such as the study author's daughter) remember what they learned.


    With many preschools boasting an expansive curriculum, naps sometimes fall by the wayside. Psychologist Rebecca Spencer of the University of Massachusetts, Amherst, decided to find out if that was a problem for the 3- to 5-year-old set.

    She and her colleagues taught young children a memory game that involved finding matching picture cards. On one day, kids napped after learning the game; on another, they were kept awake. They played the game after napping (or not) and again the next morning.

    The "habitual" nappers—those accustomed to taking naps—remembered about 15% fewer cards if deprived of a nap, the team reported online this week in the Proceedings of the National Academy of Sciences. And the sleep-deprived nappers never caught up: When playing the game the next day, they still performed more poorly than when they napped. "They need that sleep close to learning" for it to take root, Spencer says.

    Spencer and her students also studied the brain activity of 14 children in their sleep laboratory. They found "sleep spindles," short bursts of activity associated with memory processing. "If they need the nap," Spencer says, "they should get the nap."

  2. Fascinatin' Rhythms

    Different beat.

    The marine worm Platynereis dumerilii matures in sync with the phases of the moon.


    Circadian clocks keep animals in step with Earth's daily solar cycle. But many animals also stay in sync with other oscillations, such as tides and the phases of the moon. Two papers published this week in Current Biology and Cell Reports show that these alternate rhythms are driven by molecular clocks that are independent of the one driving circadian activities.

    Researchers in the United Kingdom studied both circadian and tidal cycles in the speckled sea louse, the marine crustacean Eurydice pulchra. The louse changes the color pattern on its shell on a daily cycle, but is also more active at high tide, while swimming less at low tide. The researchers showed that by changing the animals' exposure to light or vibration (to simulate tides), they could manipulate the two cycles independently of each other, settling an old debate about whether the tidal clock was simply a subset of the circadian one.

    Austrian researchers studying the marine bristle worm Platynereis dumerilii found similar evidence that the lunar-driven clock that controls the animals' maturation—they respond to changes in moonlight—is separate from the circadian one. It's likely, the researchers say, that many animals carry multiple clocks.

  3. Multiple Lineages for MERS

    A new genetic analysis of Middle East respiratory syndrome (MERS) reveals that several varieties of the deadly virus are circulating in Saudi Arabia, leading some scientists to believe it reached humans from multiple sources. The origin of the virus, which has killed 58 people since 2012, is still unclear.

    Virologist Paul Kellam of the Wellcome Trust Sanger Institute in Hinxton, U.K., and colleagues sequenced the genomes of virus samples from 21 patients in Saudi Arabia and constructed a genetic tree based on differences between the samples. The analysis, published online last week in The Lancet, identifies at least three distinct lineages of MERS. The variation among genomes collected within days of each other suggests that either the virus has evolved while moving through a large asymptomatic population, or that it diversified in animals and infected humans on several occasions. The authors favor this second interpretation, which highlights the need to identify an animal source and limit its contact with humans, Kellam says. Other researchers say both scenarios are equally plausible from the available data.