双语阅读:人类300多年的认知都错了,新研究发现精子居然有这样的花式运动

最新研究发现,精子的游动方式和我们想象的完全不一样

翻译:涂博士(微信号:jefftu95)
绘图:Phyllis(微信号:phyllis2599)

新的研究颠覆了人类三个多世纪以来关于精子如何运动的认知。

在显微镜下,人类的精子似乎像摇摆的鳗鱼一样游动,精子尾巴在寻找卵子受精时来回旋转。

但是现在新的3D显微镜和高速视频显示出精子根本不会以这种简单和对称的方式游动。相反,由于它们的尾巴只向一侧拍打,它们会以剧烈的自旋来弥补由其产生的效果。

英国布里斯托大学数学家赫尔姆斯·加德哈(HermesGadêlha)说:“这就好像说你是一个游泳者,但你游泳的时候只能向一侧踢腿。如果你在游泳池里这样游泳,你会一直在水里转圈。……大自然非常聪明,发明了以一种非常复杂,巧妙的方式向前游动。”

奇怪的游泳者

第一个近镜头观察到人类精子特写的人是被称为微生物学之父的荷兰科学家Antonie van Leeuwenhoek。1677年,范·列文虎克(van Leeuwenhoek)用他新开发的显微镜观察自己的精液,第一次看到液体中充满了微小的,摆动的细胞。

在2D显微镜下,精子很明显是由尾巴向前推动的,当精子头旋转时,尾巴似乎在左右摆动。在接下来的343年中,人类对精子的运动方式一直是这样理解的。

英国谢菲尔德大学男科学教授艾伦·佩西(Allan Pacey)说:“ 很多科学家一直猜测精子尾巴的移动可能和一个非常重要的3D元素相关,但是迄今为止,我们一直没有能够可靠地进行此类测量的技术,”。艾伦·佩西教授本人没有参与这项研究。

佩西教授在给Live Science的电子邮件中写道,因此,这项新研究是“向前迈出的非常重要的一步”。

墨西哥国立自治大学的Gadêlha和他的同事们从“蓝天探索”项目中开始了这项研究。他们使用能够进行三维成像的显微镜技术和每秒可捕获55,000帧的高速相机,将人类精子的游动记录在显微镜载玻片上。

加德哈(Gadêlha)告诉《 Live Science》:“我们发现的结果完全令人惊讶,因为它完全打破了我们的认知体系”。

精子的尾巴不是像鞭子一样左右摆动。相反,他们只能朝一个方向跳动。为了从不对称的尾巴运动中向前扭转,精子头部在尾巴旋转的同时以抖动的方式旋转。头部旋转和尾巴实际上是由两个不同的细胞机制控制的两个独立的运动,但当它们结合在一起时,结果就像是旋转的水獭或旋转的钻头。在360度旋转的过程中,尾巴单向一侧摆动的效果被平衡了,两种运动加在一起的效果就是向前推进。

Gadêlha说:“精子甚至都没有游泳,精子只是在液体中向前钻动。”

研究人员今天(7月31日)在《科学进展》杂志上发表了他们的发现。

在开始阅读英文原文之前,请先复习下列核心词汇​:

sperm - n. 精子
swim - v. 游泳
contributor - n. 贡献者,作者
research - n. 研究
upend - v. 推翻
microscope - n. 显微镜
wiggle - v. 摆动
eel - n. 鳗鱼
tail - n. 尾巴
gyrate - v. 旋转
egg - n. 卵子
fertilize - v. 受孕
andrology - n. 男科学
symmetrical - adj. 对称的
motion - n. 运动
rollicking - adj.  欢闹的 
spin - v. 自旋,转动
microbiology - 微生物学
fluid - n. 液体
tiny - adj. 小的
ingenious - adj. 巧妙的 
postulate - v. 假定,猜测
element - n. 元素
measurement - n. 测量
dimension - n. 维度
forward - adv. 向前
propulsion - n. 推进,动力
cellular - adj. 细胞的
drill - v. 钻
even out - 均匀掉,平衡掉

在复习了以上词汇后,请将下面的英文原文一口气读完,不要在中途停下来去查那些不认识的单词。有了上面的核心单词打底,你完全可以将整篇文章读完并且理解里面的大致意思。记住,你只要做到大致明白就可以了。

阅读能力和阅读量成正比,要提高阅读量,必须是大量的泛读,如果要对每个不懂的单词都去查字典,那么就不可能通过大量的泛读来提高你的阅读量。

如果你对某篇泛读文章特别喜欢,可以在泛读一遍以后再慢慢地精读。如果在精读的过程中对某些句子不是太明白需要讲解,或者你希望以后多看到哪方面的双语阅读,欢迎联系涂博士(微信号:jefftu95)。

Sperm don't swim anything like we thought they did, new study finds

By Stephanie Pappas - Live Science Contributor

New research upends more than three centuries of beliefs about how sperm move.

Under a microscope, human sperm seem to swim like wiggling eels, tails gyrating to and fro as they seek an egg to fertilize. 

But now, new 3D microscopy and high-speed video reveal that sperm don't swim in this simple, symmetrical motion at all. Instead, they move with a rollicking spin that compensates for the fact that their tails actually beat only to one side. 

"It's almost like if you're a swimmer, but you could only wiggle your leg to one side," said study author Hermes Gadêlha, a mathematician at the University of Bristol in the U.K. "If you did this in a swimming pool and you only did this to one side, you would always swim in circles. … Nature in its wisdom came [up] with a very complex, ingenious way to go forward." 

Strange swimmers

The first person to observe human sperm close up was Antonie van Leeuwenhoek, a Dutch scientist known as the father of microbiology. In 1677, van Leeuwenhoek turned his newly developed microscope toward his own semen, seeing for the first time that the fluid was filled with tiny, wiggling cells. 

Under a 2D microscope, it was clear that the sperm were propelled by tails, which seemed to wiggle side-to-side as the sperm head rotated. For the next 343 years, this was the understanding of how human sperm moved. 

"Many scientists have postulated that there is likely to be a very important 3D element to how the sperm tail moves, but to date we have not had the technology to reliably make such measurements," said Allan Pacey, a professor of andrology at the University of Sheffield in England, who was not involved in the research. 

The new research is thus a "significant step forward," Pacey wrote in an email to Live Science. 

Gadêlha and his colleagues at the Universidad Nacional Autónoma de México started the research out of "blue-sky exploration," Gadêlha said. Using microscopy techniques that allow for imaging in three dimensions and a high-speed camera that can capture 55,000 frames per second, they recorded human sperm swimming on a microscope slide. 

"What we found was something utterly surprising, because it completely broke with our belief system," Gadêlha told Live Science. 

The sperm tails weren't wiggling, whip-like, side-to-side. Instead, they could only beat in one direction. In order to wring forward motion out of this asymmetrical tail movement, the sperm head rotated with a jittery motion at the same time that the tail rotated. The head rotation and the tail are actually two separate movements controlled by two different cellular mechanisms, Gadêlha said. But when they combine, the result is something like a spinning otter or a rotating drill bit. Over the course of a 360-degree rotation, the one-side tail movement evens out, adding up to forward propulsion.

"The sperm is not even swimming, the sperm is drilling into the fluid," Gadêlha said. 

The researchers published their findings today (July 31) in the journal Science Advances.

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