SSS 2011-03-04（在线收听）

Every villain has his Achilles' heel. And microscopic scoundrels are no exception. The challenge for those who wish to ward off microbial bad guys is to identify that weak spot. Now, scientists studying the toxoplasmosis parasite think they've done just that. They share the secret in the Proceedings of the National Academy of Sciences.

The toxo parasite is similar to the one that causes malaria. So finding a way to prevent these rogues from reproducing is high on researchers' to-do lists. The bugs are tricky to take down, in part because they're unpredictable in the way they multiply. Sometimes they get in and get busy making babies. Other times they copy their chromosomes but hold off parceling them out to their army of offspring until the time is right.

This flexibility has benefits, but it also has a drawback: the parasites have to keep track of their chromosomes…even as they change their minds about how and when to divvy them up. Now scientists have discovered a structure…unique to these parasites…that keeps their DNA in a tidy bundle through thick and thin. Find a drug that breaks that bundle, and we could destroy these parasites' devious plans.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Karen Hopkin.