(单词翻译:单击)
听力文本
This is Scientific American's 60-second Science. I'm Karen Hopkin.
They say that Marie Antoinette's hair turned white the night before she lost her head to the guillotine. But can stress really have such a dramatic effect on hair color? A new study in mice concludes that it can and credits overactive nerves with stripping the color from the animals' locks—and possibly ours.
Researchers at Harvard's Stem Cell Institute were interested in the stress and hair color issue. So they decided to take a closer look at those stem cells that give rise to melanocytes—the cells that pump pigments into each hair follicle. The stem cells were an obvious target.
"Because changes in the stem cell population translate to changes in hair color, which are very visible and easy to identify."
Ya-Chieh Hsu, the study's senior author.
To start, she and her colleagues subjected mice to some rodent-sized stressors—like having their cage tilted, their bedding dampened or their lights left on all night.
"So what did we find? We found that stress indeed leads to premature hair graying in mice. But it took a long time for us to actually narrow down how it occurs."
First, they thought it could be the immune system attacking the melanocyte stem cell population.
"However, mice lacking immune cells still show premature hair graying under stress."
Then they thought the key factor could be cortisol, the quintessential stress hormone.
"But when we removed the adrenal glands from the mice so they cannot produce cortisol-like hormones, their hair still turned gray under stress."
That's when they turned their attention to the sympathetic nervous system, which orchestrates the body's overall reaction to stress, including the classic fight-or-flight response. Those nerves reach out to our muscles, organs and, yes, even our hair.
"The nerve terminals wrap around each hair follicle like a ribbon."
And when Hsu and her team cut those connections, the stem cells were spared, and the animals kept their shiny black coat even in the face of minor discomfort. The findings appear in the journal Nature.
It's unclear whether the same sympathetic nerves make us gray as we age. But the results provide hope that we may someday be able to fight to hold onto our natural hair color—and avoid that monthly flight to the hairdresser.
Thanks for listening for Scientific American's 60-second Science. I'm Karen Hopkin.
参考译文
这里是科学美国人——60秒科学。我是凯伦·霍普金。
据说玛丽·安托瓦内特在上断头台的前一晚，头发一夜变白。但压力真能对头发颜色产生如此巨大的影响吗？一项在老鼠身上进行的新研究得出结论称，确实可以，而且可以认为过度活跃的神经会使动物——可能还有我们的发色脱色。
哈佛干细胞研究所的研究人员对压力和头发颜色问题产生了兴趣。因此，他们决定更仔细地研究产生黑色素细胞的干细胞，黑色素细胞是将色素注入每个毛囊的细胞。干细胞很容易成为研究目标。
“因为干细胞群的变化转化为发色变化，这种变化非常明显，也很容易识别。”
许雅捷是这项研究的资深作者。
首先，她和同事让老鼠承受一些小压力，比如倾斜鼠笼、弄湿被褥或通宵亮灯。
“我们发现了什么？我们发现压力确实会导致老鼠毛发过早变白。但我们花了很长时间才真正弄清导致这种情况发生的原因。”
他们一开始认为可能是免疫系统攻击黑色素细胞干细胞群。
“然而，缺乏免疫细胞的老鼠在压力下仍会出现毛发过早变白的现象。”
之后他们认为关键因素可能是皮质醇，这是一种典型的压力激素。
“但当我们移除老鼠的肾上腺，使其不能产生皮质醇类激素时，它们的毛发在压力下仍然会变白。”
这时他们将注意力转向了交感神经系统，该系统负责协调身体对压力的整体反应，包括经典的战斗或逃跑反应。这些神经延伸至我们的肌肉、器官以及……没错，甚至我们的头发。
“神经末梢像缎带一样缠绕在每个毛囊周围。”
许雅捷及其团队切断这些联系时，干细胞未遭损害，而老鼠即使面对轻微不适也能保持它们闪亮的黑色皮毛。这项研究发表在《自然》期刊上。
目前尚不清楚交感神经是否也会让我们的头发随年龄变白。但研究结果给我们带来了希望，我们或许某天能保持住自己的自然发色，避免每月都去理发店染店。
谢谢大家收听科学美国人——60秒科学。我是凯伦·霍普金。
译文为可可英语翻译，未经授权请勿转载！
重点讲解
重点讲解：
1. credit sb. with sth. 认为是…的功劳；把…归于；
The staff are crediting him with having saved Hythe's life.
职员们称赞他救了海丝的命。
2. give rise to 引起；使发生；
Low levels of choline in the body can give rise to high blood-pressure.
体内胆碱水平过低会引起高血压。
3. in the face of 面对；在…面前；
They showed great perseverance in the face of difficulty.
他们面对困难表现了坚强的毅力。
4. hold onto 保住，守住；
A few of the men hold onto their composure by gripping armrests and clenching teeth, but their fear was written all over them.
只有几个男人通过抓住椅子把手咬紧牙关保持住镇静，但是他们的恐惧都写在他们脸上。
