Science  18 Oct 2013:
Vol. 342, Issue 6156, pp. 296
  1. Protein Pathway Links Exercise to Brain Health

    Pumped up.

    A group of molecules link exercise to mental benefits.


    Exercise has well-known mental benefits, from counteracting depression and aging to fighting Alzheimer's and Parkinson's diseases. Scientists have struggled to account for this—but research published last week in Cell Metabolism reveals an important molecular link: a protein called FNDC5, produced in muscle cells during exercise and released into the bloodstream in a form called irisin. FNDC5 is also present in the brain and is thought to help neurons develop.

    The researchers found that in mice, exercise increases FNDC5 in the hippocampus, a brain region responsible for learning and memory. Ramping up FNDC5 production in mouse brain cells developing in a dish boosted levels of a crucial protein called brain-derived neurotrophic factor (BDNF), involved in maintaining healthy neurons and creating new ones. Most surprisingly, the researchers say, injecting mice with a virus that causes their livers to secrete more irisin also increased BDNF in the hippocampus, suggesting that irisin, or some unidentified protein that it regulates, could be crossing the blood-brain barrier to work its effects.

  2. Potential Bioweapon Kept Secret

    Sometimes, transparency in science must take a back seat to security concerns. That's what the editors of The Journal of Infectious Diseases decided in the case of two papers reporting the discovery of a new type of botulinum toxin. Fearing that that information could be exploited by terrorists seeking bioweapons, the editors and the authors of the papers, published online last week, decided that it was prudent not to publish the sequence of the bacterial gene that produces the protein, named Botulinum Toxin H.

    Antitoxins exist for the seven previously discovered botulinum toxins (with suffixes A to G), but the new toxin did not respond to any of these. In an editorial accompanying the papers, the journal said that the gene sequence would be made public in the future, after an antitoxin is developed.

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