Science  16 Dec 2011:
Vol. 334, Issue 6062, pp. 1480
  1. UFO: Unidentified Fossilized Object?

    No match.

    Dead Thiomargarita (top) and ancient fossils (bottom).


    In 1997, the unearthing of some unusual 570-million-year-old fossils in southern China caused quite a stir; their discoverers decided that these salt replicas of cells were embryos, making them the oldest animals ever found. Other scientists countered that these Doushantuo fossils were actually giant, sulfur-metabolizing bacteria called Thiomargarita. Palaeontologist Philip Donoghue and colleagues at the University of Bristol in the United Kingdom have now studied how this bacterium and embryos decay to figure out the fossils' true identity. They found they couldn't kill Thiomargarita and instead isolated dead bacteria from sediment samples. When they examined dead Thiomargarita, expired sea urchin embryos, and some of the original Doushantuo fossils using x-ray light from a synchrotron, they found that the bacteria looked nothing like the famous fossils. Thiomargarita cells became empty spheres as they decayed, whereas the fossils showed evidence of a lot of internal structure, the researchers reported last week in Proceedings of the Royal Society B.

  2. Rise of the U.S. Bedbug

    Genetic studies suggest that the amazing rise of bedbugs in the United States in the past decade stems from multiple invasions from overseas, and that, thanks to high levels of inbreeding, a single mated female can cause an infestation plaguing an entire apartment building.


    Some researchers have suggested that bedbugs came from U.S. poultry farms, where the insects are also found; others suspected foreign sources, because the farm-based bugs are still susceptible to pyrethroid insecticides, while the human pests are resistant. When entomologist Coby Schal of North Carolina State University in Raleigh and his colleagues compared DNA from bedbugs along the East Coast, they discovered very large genetic differences between populations, suggesting very diverse origins. Nearby populations were not more similar than distant ones, which makes it unlikely that the bugs were home-grown or introduced to the United States only once or twice, Schal said last week at the annual meeting of the American Society of Tropical Medicine and Hygiene in Philadelphia. There were “astoundingly” few genetic differences within populations, however, indicating a high inbreeding rate that allows a single female to start a new population.

  3. Connected Brain Regions Grow Up Together

    In sync.

    Coordinated maturation in some regions of the brain.


    Brain regions that work together grow together. The brain is more than the sum of its parts, and connectivity is key to its many functions. To look for evidence of how that connectivity develops, Armin Raznahan, a child psychiatrist and neuroscientist at the National Institute of Mental Health in Bethesda, Maryland, and his colleagues analyzed magnetic resonance imaging scans of brain anatomy from 108 healthy children who had had at least three scans taken between the ages of 9 and 22.

    The researchers calculated the thickness of the cerebral cortex, the brain's outermost layer of tissue, which is involved in virtually every aspect of cognition and behavior. In general, the cortex thickens in early childhood and thins in adolescence or adulthood. These changes occurred simultaneously in brain regions that talk to each other a lot, such as areas of the temporal and frontal cortex involved in language, reasoning, and decision making, he and his colleagues reported last week in Neuron. In contrast, parts of the cortex involved in narrowly focused tasks, such as making sense of sights and sounds or telling muscles what to do, appear to mature more independently. The work could have implications for understanding various puzzles in neuroscience, such as what goes wrong in autism or why adolescent boys are prone to risky behavior, says Raznahan.

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