Science  16 Nov 2012:
Vol. 338, Issue 6109, pp. 870

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  1. I Scratch, You Itch


    Seeing someone yawn or hearing someone laugh makes you likely to follow suit. The same goes for scratching an itch. Now, for the first time, researchers have investigated the neural basis of contagious itch, identifying several brain regions whose activity predicts how susceptible people are to feeling itchy when they see someone else scratch.

    Researchers in the United Kingdom showed volunteers video clips of people scratching an arm or a spot on their chest. Sure enough, subjects reported feeling more itchy, and most scratched themselves at least once during the experiment. When a subset of the volunteers watched the videos inside a functional magnetic resonance imaging scanner, the scans revealed activity in several of the same brain regions known to fire up in response to an itch-inducing histamine injection. Activity in three of these areas correlated with subjects' self-reported itchiness, the team reported online on 12 November in the Proceedings of the National Academy of Sciences. Personality tests suggested that the trait that best predicts susceptibility to contagious itch is neuroticism, not empathy, as some researchers have suggested.

  2. Protein Makes Sperm Flee

    A compound that causes immature sperm cells to flee the testes early may provide new leads for contraceptives.

    Scientists pursuing a “male pill” have recently found multiple ways to disrupt sperm production, usually by shutting down genes and proteins unique to the testes (Science, 19 October, p. 318). Now, a team led by C. Yan Cheng of the Population Council's Center for Biomedical Research in New York City has identified a new way to stop spermatogenesis: disrupting the blood-testis barrier, a cellular firewall between the testes and blood circulation.

    When Cheng's team injected a special protein fragment into rat testes, the blood-testis barrier broke down. This caused immature sperm to drift out of the testes early, before they were capable of fertilizing eggs. More importantly, these changes were reversible. The team reported their findings on 13 November in Nature Communications.

    Any potential male contraceptive would be many years off and would require many more tests. Cheng's team, for instance, has not tested whether rats injected with this protein fragment father fewer offspring. But Cheng says the advantage of this protein over other potential contraceptives is that the body produces it naturally in small amounts, so it's likely to be well tolerated.