Parasite That Makes Mice Fearless of Cats


Thu, May 2nd, 2013 10:00 by capnasty NEWS

In the National Geographic's Not Exactly Rocket Science, Ed Yong examines a single-celled parasite called Toxoplasma gondii that, when it infects mice, turns them suicidal -- right into the jaws of a cat. The reason behind it is pretty amazing:

T.gondii (or Toxo for short) infects a wide variety of mammals, but it only completes its life cycle in the guts of a cat. To get there, Toxo has ways of subverting the behaviour of dead-end hosts like mice. Its machinations are subtle, so subtle that it’s normally hard to tell an infected mouse from an uninfected one. But the difference becomes obvious when there’s cat pee in the air. Normal mice, even lab-born ones that have never met a cat, have an innate fear of cat smells. Those infected with Toxo do not. They (and their parasites) are more likely to end up in a cat.

Toxo also influences the brain of Wendy Ingram from the University of California at Berkeley. She has long been obsessed with the brain and fascinated by Toxo’s dominion over it. “I was struck by the idea that a single celled parasite 'knows’ more about our brains than we do,” she says. Working as a PhD student in the labs of Michael Eisen and Ellen Robey, Ingram started trying to understand how Toxo affects the brains of rodents. And her experiments already promise to revise what we know about this mind-bending parasite.



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