Japan scientists develop fearless mice

TOKYO - Cat and mouse may never be the same. Japanese scientists say they've used genetic engineering to create mice that show no fear of felines, a development that may shed new light on mammal behavior and the nature of fear itself.

Scientists at Tokyo University say they were able to successfully switch off a mouse's instinct to cower at the smell or presence of cats — showing that fear is genetically hardwired and not learned through experience, as commonly believed.

"Mice are naturally terrified of cats, and usually panic or flee at the smell of one. But mice with certain nasal cells removed through genetic engineering didn't display any fear," said research team leader Ko Kobayakawa.

In his experiment, the genetically altered mice approached cats, even snuggled up to them and played with them. Kobayakawa said he chose domesticated cats that were docile and thus less likely to pounce.

Kobayakawa said his findings, published in the science magazine Nature last month, should help researchers shed further light on how the brain processes information about the outside world.


参考译文:
日本科学家培育出不怕猫的老鼠

东京的报道，猫和鼠从不会一样的。日本科学家说他们已经利用基因工程造出了不怕猫的老鼠，这个发展揭示了哺乳动物行为和其恐惧的本性。

科学家在东京大学说他们能够成功地消除老鼠的本性，这种本性就是当它们嗅到或看到猫的样子的时候就会害怕。这表明了害怕是基因影响的，并非普遍认为的由经验得来。

研究小组带头人Ko Kobayakawa说，老鼠天生就是怕猫的，而且经常是在嗅到猫的气味就会害怕并逃跑。但通过基因工程移除了某些鼻细胞的老鼠就不会显出任何的害怕表现。

在他的实验中，基因改变了的老鼠会靠近，甚至偎依在猫身上，还会跟它们玩。Kobayakawa说他挑选了家养的猫，它们都很温顺所以很少突袭。

Kobayakawa说他的发现发表在了上个月的《自然》科学杂志上面，并将会有助于研究人员发现大脑如何处理来自外界的信息。