Science  25 Jan 2013:
Vol. 339, Issue 6118, pp. 379

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  1. Leprosy Bacterium Reprograms Cells


    Despite its ancient origins, leprosy remains mysterious—in part because the bacterium that causes leprosy can't be grown in a lab, so it can only be studied in infected humans, armadillos, and genetically engineered mice. Now, a new study in mice shows how the bacterium Mycobacterium leprae employs a bit of biological trickery to do its damage: It reprograms certain nerve cells to become like stem cells and uses them to infiltrate the body's muscle and nervous systems.

    Biologist Anura Rambukkana of the University of Edinburgh in the United Kingdom and colleagues isolated mice's Schwann cells, which sheathe nerves and help transmit nervous system signals, and infected them with M. leprae. The bacteria turned off genes that were expressed in mature Schwann cells and turned on genes associated with earlier stages of cell development—transforming the cells into immature, stemlike cells.

    When reintroduced into the mice, some altered cells migrated to muscle tissues, spreading the bacteria. The results suggest that M. leprae hijacks Schwann cells so it can use them to infiltrate other tissues in the body, the team reported online last week in Cell.

  2. Dog Domestication Tied to Starchy Diets

    Pass the potatoes.

    Dogs adapted to human diets with more starch.


    The canine's shift from wolf pack to family pet wasn't just about their good behavior. Wolves eat mostly meat, but the first dogs likely dined on roots and cereals, like their human friends—and their genomes reflect that shift. Evolutionary geneticist Erik Axelsson from Uppsala University in Sweden and colleagues compared wolf and dog DNA, looking for regions that were the same in all dogs but variable in wolves; such a lack of variation could indicate that the DNA was important for survival during domestication. Among the more surprising finds were genes for digesting starch. For example, in part depending on the breed, dogs had four to 30 copies of the gene for amylase—(wolves have two copies) and were better at breaking down starch, the researchers reported online this week in Nature. "It hints that there are a lot more [genes] to be found that we don't really think about as domestication events," says Elaine Ostrander, a geneticist at the National Human Genome Research Institute in Bethesda, Maryland, who was not connected to the study.