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科学美国人60秒: 好奇害死了……老鼠?

所属教程:科学美国人60秒科学系列 更新:01-26
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Curiosity Killed the ... Mouse?

好奇害死了……老鼠?

Parasites live on or even inside another organism. And some can even change the behavior of their host to boost the odds of their transmission. Take the single-celled Toxoplasma gondii. Mice infected with this bug appear to become attracted to the smell of cat pee, an odor that uninfected mice smartly avoid. The infection thus raises the chances that a mouse will wind up in a cat’s mouth. Obviously, bad news for the mouse—but good news for the parasite, which needs a kitty to complete its life cycle and spread to additional hosts.

寄生虫寄生在另一个有机体上,甚至寄生在另一个有机体内。有些甚至可以改变宿主的行为来增加传播的几率。以单细胞弓形虫为例。感染了这种病毒的老鼠似乎会被猫尿的气味所吸引,而未感染的老鼠会聪明地避开这种气味。因此,感染增加了老鼠进入猫嘴里的机会。很明显,这对老鼠来说是个坏消息,但对寄生虫来说却是个好消息,因为寄生虫需要小猫来完成它的生命周期并传播到其他的宿主。

Devious, indeed. But it turns out this cunning scheme may be less precisely targeted than it initially appears—because a new study finds that Toxoplasma doesn’t specifically eliminate a mouse’s natural aversion to cats. Rather the infection makes them generally less anxious and more adventurous—which makes them them curious about cats and pretty much everything else. Their work appears in the journal Cell Reports.

狡猾的,事实上。但事实证明,这个狡猾的计划可能没有最初看起来那么精确,因为一项新的研究发现,弓形虫并不能特别消除老鼠对猫天生的厌恶。相反,感染通常会让它们变得不那么焦虑,更爱冒险——这让它们对猫和几乎所有的东西都感到好奇。他们的研究发表在《细胞报告》杂志上。

“The story about Toxoplasma gondii manipulating the behavior of its host is simply fascinating.”

Biologist Ivan Rodriguez of the University of Geneva, one of the study’s senior authors.“It was particularly intriguing for us to understand how the parasite achieves a specific alteration of the neural circuits involved in the response toward feline predators—something that has never been elucidated.”

“刚地弓形虫操纵宿主行为的故事非常有趣。”日内瓦大学的生物学家Ivan Rodriguez是这项研究的主要作者之一。“对我们来说,了解这种寄生虫如何对猫科捕食者做出反应的神经回路进行特定的改变是特别有趣的——这一点从未被阐明过。”

So Rodriguez and his colleagues set out to determine the molecular mechanisms that underlie this legendary feline fatal attraction. For their first step:

因此,罗德里格斯和他的同事们着手研究这种具有传奇色彩的猫科动物致命吸引力背后的分子机制。第一步:

“We decided to perform a quite broad panel of behavioral assays with infected mice in order to get an overview of how the parasite affects its host. We quickly observed that infected mice were less anxious, were more explorative and reacted quite differently than control mice when confronted with potential threats.”

“我们决定对受感染的老鼠进行一项相当广泛的行为测试,以了解寄生虫是如何影响其宿主的。”我们很快发现,受感染的老鼠在面对潜在威胁时,表现得不那么焦虑,更有探索性,反应也与对照组老鼠大不相同。”

For example, mice infected with Toxoplasma were quicker to check out the far reaches of an elevated maze than their uninfected comrades. They interacted with the human investigators’ hands and were unperturbed when an anesthetized rat was plonked into the middle of their cage—an event that caused uninfected mice to freeze in their tracks.

例如,感染了弓形虫的老鼠比未感染弓形虫的老鼠能更快地检测出高架迷宫的远处。当一只被麻醉的老鼠被扔到笼子中央时,它们和人类调查员的手互动,并没有受到干扰——这一事件导致未受感染的老鼠在它们的运动轨迹中冻结。

And the infected mice in this study did indeed show an attraction to the urine of bobcats. But they were even more interested in the scents of foxes and guinea pigs. Of course, whether or not infected mice are drawn specifically to the smell of cats, the parasite still gets what it wants, says Rodriguez.

在这项研究中,受感染的老鼠确实对山猫的尿液有吸引力。但他们对狐狸和豚鼠的气味更感兴趣。当然,不管受感染的老鼠是否特别喜欢猫的气味,寄生虫还是能得到它想要的,罗德里格斯说。

“The end result is to favor the transmission of the infected rodent to the cat.”As to the mechanism, it appears that the parasite triggers a general inflammation of the brain. “One interesting finding is that we observe a correlation between the level of inflammation and the severity of behavioral alterations.”Madlaina Boillat, a graduate student in the Rodriguez lab.

“最终的结果是有利于受感染的啮齿动物传染给猫。“至于其机制,寄生虫似乎引发了大脑的普遍炎症。“一个有趣的发现是,我们观察到炎症程度与行为改变的严重程度之间存在相关性。罗德里格斯实验室的研究生玛德莱娜·博伊拉特(Madlaina Boillat)说。

She and Rodriguez will continue to explore how neuroinflammation sends mice to their almost certain doom. Does it render these mice blind to danger—or endow them with the kind of curiosity that is usually associated with their feline foes?

她和罗德里格斯将继续探索神经炎症是如何让老鼠走向灭亡的。它是使这些老鼠对危险视而不见,还是赋予它们一种通常与它们的猫科敌人相联系的好奇心?

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