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This is Scientific American's 60-Second Science. I'm Steve Mirsky. Got a minute?

When a healthy rat smells a cat, it flees. But rats infected with the Toxoplasma brain parasite¹ actually follow cat odors, often presumably to their doom², red in tooth and claw. Now researchers have found out exactly what's going on in the rat's infected brain—it's in love. The study is in the journal Public Library of Science ONE.

That Toxo-infected rats approach cats has long been a well-known example of a parasite manipulating the behavior of its mammalian host. The protozoan needs to be in a cat's intestine³ to reproduce. It then gets pooped out and has to find its way into another cat to continue its fabulously⁴ glamorous⁵ lifestyle. Rats that touch the poop and then get eaten by a cat can complete the circuit.

The new research reveals that when a Toxo-infected rat smells cat urine, it has increased activity in brain regions associated with sexual attraction. Which the researchers say is "compelling evidence that Toxoplasma overwhelms the innate⁶ fear response by causing, in its stead, a type of sexual attraction to the normally aversive cat odor." That's right, the rat is turned on. Before it's permanently⁷ turned off.

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

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收听单词发音

1 parasite
n.寄生虫；寄生菌；食客
参考例句：
The lazy man was a parasite on his family.那懒汉是家里的寄生虫。 I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

2 doom
n.厄运，劫数；v.注定，命定
参考例句：
The report on our economic situation is full of doom and gloom.这份关于我们经济状况的报告充满了令人绝望和沮丧的调子。 The dictator met his doom after ten years of rule.独裁者统治了十年终于完蛋了。

3 intestine
adj.内部的；国内的；n.肠
参考例句：
This vitamin is absorbed through the walls of the small intestine.这种维生素通过小肠壁被吸收。 The service productivity is the function,including external efficiency,intestine efficiency and capacity efficiency.服务业的生产率是一个包含有外部效率、内部效率和能力效率的函数。

4 fabulously
难以置信地，惊人地
参考例句：
The couple are said to be fabulously wealthy. 据说这对夫妇家财万贯。 I should say this shirt matches your trousers fabulously. 我得说这衬衫同你的裤子非常相配。

5 glamorous
adj.富有魅力的；美丽动人的；令人向往的
参考例句：
The south coast is less glamorous but full of clean and attractive hotels.南海岸魅力稍逊，但却有很多干净漂亮的宾馆。 It is hard work and not a glamorous job as portrayed by the media.这是份苦差，并非像媒体描绘的那般令人向往。

6 innate
adj.天生的，固有的，天赋的
参考例句：
You obviously have an innate talent for music.你显然有天生的音乐才能。 Correct ideas are not innate in the mind.人的正确思想不是自己头脑中固有的。

7 permanently
adv.永恒地，永久地，固定不变地
参考例句：
The accident left him permanently scarred.那次事故给他留下了永久的伤疤。 The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。