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微生物其实什么都不像

Microbes Don’t Actually Look Like Anything

Journey to the microcosmos
《微观旅途》
This is a ciliate, just a eukaryotic microbe waving
这是一只纤毛虫 它是一种真核微生物
its cilia around under our microscope.
它正在我们的显微镜下挥动纤毛
And this is the same ciliate.
这是同一只纤毛虫
And yup, here it is again… …and again.
没错 这也是它 还是它
But as you’re probably noticing,
但你可能注意到了
while the rough outline of this organism
虽然这只微生物在各个镜头里的大致轮廓
seems the same from shot to shot,
看起来一样
the ciliate itself and the world around it clearly look very different.
但是它自身及其周围的环境却明显不同
Colors change, details are more apparent.
颜色改变 细节更加清晰
In one case
在这一例
the organism seems to be lit from within.
这个微生物看起来就像是从内部点亮了
On this channel,
在这个频道
we’re constantly flipping between different ways
我们会不断地通过不同的方式
of capturing images of organisms.
捕捉生物的图像
So which one of them is what they actually look like?
那么 哪一个才是它们真实的样子?
Well…none of them.
呃……都不是
Anything you see through a microscope is an image,
通过显微镜看到的任何东西都只是图像
which in our case, means that everything we show you on this channel,
在我们的例子中 即这个频道展示给你的一切
every frame, is not the microbial world itself.
甚至每一帧都不是微观世界真正的样子
It’s an interpretation of the life on the other side of our objective,
这只是对物镜另一端的生物的一种展示
translated through the lens into details, and shapes, and colors—
通过镜头展现出各种细节 形状和颜色——
all affected by the way we light up the life we want to see.
这些都受到我们照亮它们的方式的影响
Light is amazing, it’s also very weird.
光很奇妙 也很奇怪
It travels in waves,
光以波的形式传播
and as it interacts with particles and materials,
当光与粒子和物质相互作用时
it scatters and shifts.
它会发生散射和偏移
Even if we can’t actually see those light waves in motion,
即使我们看不到光波运动
so much of what we observe in the world around us
但我们在周围世界中观察到的很多东西
is rooted in the physical properties that define those waves—
都基于用来定义这些波的物理特性——
like how we can observe certain frequencies of light as colors.
比如人眼怎样将特定频率的光感知为颜色
But waves have far more to them than just their frequency,
但波对它们的影响远不只有频率
and microscopy has combined the resourcefulness of many different sciences
显微技术结合各种学科的丰富成果
to use light to give us different ways
利用光为我们提供了不同的方式
to peer into the microbial world.
来窥视微观世界
So let’s start simple.
让我们从简单的开始吧
Good old fashioned white light.
十分老式的白光
Early microscopists used oil lamps and sunlight
早期的微观工作人员使用油灯和日光
to see through their microscopes,
为显微镜提供光线
and while the technology has changed,
尽管技术发生了变化
the simplicity of this
这种简单性
has endured into the modern technique of brightfield microscopy.
一直延续到现代的明视场显微镜技术中
It all starts with a source of light,
一切都从光源开始
though modern microscopes have their lamps built in,
即便现代显微镜有内置灯
set up underneath the stage that holds our sample.
安装在放置样本的载物台下方
Light travels from the source through a condenser,
光从光源射出 通过聚光器——
which works to focus the light onto the sample above it.
它能将光聚焦在上方的样本上
This focused light travels through the sample towards the objective lens,
聚焦后的光线穿过样本后射向物镜
which takes in an image and magnifies it
物镜将接收到的生物图像放大到
into these bright backgrounds with organisms,
这些明亮的背景中
sometimes rendered transparent by the intensity of the light.
但有时会因为光线强度而变得透明
You might say that this is as close as we
你可能会说这是我们能看到的
get to seeing what the microcosmos actually looks like,
最接近真实微观世界的样子了
but that would be like taking a 2000 watt light bulb into your living room
但这就像你在客厅放上2000瓦的灯泡
and saying, “this is what my home looks like.”
然后说:“我家就是这样”
Light affects things,
光会影响事物
and we’re not even shining light on these organisms,
我们甚至不是把光照在这些生物上
we’re shining light through them.
而是穿过它们
Now, Brightfield might seem relatively simple,
明视场技术可能看起来相对简单
but that simplicity has been incredibly powerful
但这种简单在新老科学家研究
in allowing scientists old and new to wade through microscopic waters.
微观水世界的活动中十分有效
Still, there are limitations to consider with any scientific technique,
然而任何科学技术都有局限
and one of the major challenges for brightfield microscopy,
而明视场显微镜所面临的主要挑战之一
particularly when looking at microbes, is contrast.
是对比度 这在观察微生物时尤为明显
Pigmented organisms are easy to visualize against the bright background,
颜色较深的生物在明亮的背景下容易成像
but in cases where the organism has been rendered transparent,
但在生物已经变得透明的情况下
it can be harder to distinguish their bodies from the rest of the world they inhabit.
要将它们与周围环境区分开 就比较困难了
Scientists can navigate these challenges
科学家可以使用染色剂
using stains that make certain structures more visible,
使某些结构更加明显 以此应对这些挑战
but for our purposes, we like to avoid stains
但就我们的目的而言 我们会避免使用染色剂
because they can affect the microbes themselves.
因为它们会对微生物自身造成影响
There are other ways though to contend with this challenge,
当然还有其它方法来应对这一挑战
one of which is built on one of
其中之一建立在
those simple-yet-strange properties of our world:
世界简单又奇怪的特性之一上:
you don’t always need to shine light directly onto an object to see it.
你不一定要将光线直射到物体上才能看到它
This technique is called darkfield microscopy,
这种技术称为暗视场显微
which sounds like it must be almost the opposite of brightfield microscopy.
这听起来像是与明视场显微完全相反
It’s not.
但并非如此
The two techniques are actually very similar:
这两种技术实际上非常相似:
light travels from a source through a condenser,
光从光源射出 通过聚光器
goes through the sample, and then it travels into the objective lens,
穿过样本 然后进入物镜
producing the image we see.
最终形成我们看到的图像
But what we want in darkfield microscopy
但我们想在暗视场显微技术中做到的
is for the beam of light to hit the sample,
是让光束直接照射到样本上
but not our eye.
而不是我们的眼睛里
So, in darkfield microscopy,
因此 在暗视场显微技术中
a circular disk is placed inside the condenser,
聚光器内置有一个圆盘
blocking the central part of the light
来挡住中央部分的光
from shining through the sample and into our eye..or, our camera..
避免光线穿过样本进入我们的眼睛或相机
This means that when there is no sample on the slide,
这意味着如果载玻片上没有样本
all you see is black.
你只能看到一片黑暗
But the disk doesn’t block all of the light:
但圆盘并没有阻挡所有光线
there is still a hollow cone of light that travels around the disk
它的周围仍有一个空心的光锥
unable to reach the objective or our eyes,
既不能到达物镜 也无法进入我们的眼睛
but that still hits the sample.
但仍能照射到样本
When it does, those microscopic, transparent bodies
这时 那些微小的透明生物体
scatter those hidden rays into our view.
会将隐藏的射线散射入我们的视野中
And as they do, an image of their bodies forms against a dark background,
这时 生物体能够在黑暗的背景中成像
providing us with this almost cinematic footage.
为我们提供了这电影般的镜头效果
Another method to get better contrast than brightfield microscopy
另一种获得比明视场显微更高对比度的方法
is called phase contrast microscopy,
被称为相差显微技术
and it’s built on working with a property of light
它是建立在光的一种
that we can’t actually directly experience.
我们无法直接感受到的性质上的
Microbes, or really anything, that is easily visually observed with brightfield microscopy
微生物或其他容易用明视场显微镜观察到的对象
are called amplitude objects
被称为振幅物体
because as light passes through them,
因为当光线穿过它们时
the amplitude of the light wave changes,
光波的振幅改变了
which we see as changes in light intensity.
而在我们看来 表现为光强度的变化
But there is another class of specimens: these are called phase objects.
但还有另一种称为相位物体的样本
As light passes through these objects,
当光穿过这些物体时
the waves slow down and shift slightly in phase
光波会减速 相对于周围未减速的光
compared to the unaffected light around it.
会在相位上发生很小的相移
And if you’re wondering what that means in terms of what we can see,
如果你想知道这对我们的视觉效果有什么影响
that’s the issue:
这就是问题所在:
our eyes don’t process these differences in phase.
我们的眼睛无法处理这些相位上的差异
And so in the final image,
所以在最后的图像中
these objects (or in our case, organisms)
这些物体(在我们的例子中是生物)
are very difficult to see.
是很难观察到的
Well, in the 1930s, a physicist named Frits Zernike
20世纪30年代 一位名为Frits Zernike的物理学家
developed a method
发明了一种方法
to shift the direct light just slightly enough
使直线传播的光线产生刚刚好的细微偏转
so that these changes in phase
因此这些相位上的变化
could actually be translated into changes in amplitude,
可以转化为振幅的变化
producing an image of these formerly hard-to-see phase objects
通过把相位物体当做振幅物体的方法
by essentially treating them as amplitude objects.
得到了之前很难观察到的相位物体的图像
There is a lot of physics in this that we are not going to get into,
这里涉及很多物理知识 我们不打算细讲
but the result was so important that
但是其结果是十分重要的
it would eventually win Zernike the Nobel Prize in Physics.
Zernike也因此获得了诺贝尔物理学奖
And of course, selfishly, we here appreciate his work
当然 自私点说 我们感谢他的工作
because it lets us see more of our hidden microbial friends.
因为这使我们看到了更多隐藏的微生物朋友们
And for the last type of microscopy we’ll go over today,
今天我们要讲的最后一种显微镜
we’re going to be getting into another property of light that we can’t directly see,
我们将会说到光的另一种无法直接看到的特性
and this one, can make the microcosmos glow.
而这种特性能使微观世界发光
Most of the light we see has an electrical field
我们看到的大多数光会产生电场
that vibrates in all sorts of planes relative to the direction the light is traveling in.
电场在各种平面内振动 其方向与光传播的方向有关
But that vibration can be restricted to just one plane,
但振动可以只被限制在一个方向上
and when that happens, the light is said to be polarized.
这时 我们说光发生了偏振
We can’t see the difference between polarized and unpolarized light.
我们无法分辨偏振光与非偏振光
And you might see the difference in how the world looks
不过当你戴上偏光太阳眼镜时
when you’re wearing polarized sunglasses,
你可能会发现世界看起来不一样
but these changes are brought about
但这些变化
by changes in color or intensity,
是由光的颜色和强度引起的
not the polarization of the light itself.
而不是光本身的偏振
So when does polarized light help microscopy?
那么偏振光在何时对显微技术有帮助?
Well, a lot of materials stay the same optically-speaking,
嗯 很多材料从光学角度来讲是不变的
no matter what direction you shoot light at them from.
不论光从哪个方向照射它们看起来都一样
But there are certain materials where specific properties,
但某些材料有一些特性
like how fast light travels through them,
比如光穿越它们的速度
can vary depending on which way the light is striking them.
可根据光照射的方向不同而有所差异
These materials called optically anisotropic,
这种材料被称为光学各向异性材料
can also take in a ray of light
它也能吸收一束光
and divide it into two separate beams.
并把它们拆分为两束
By aiming polarized light at our sample
通过偏振光照射样本
and then we reconstructing an image based on
然后我们根据
how the various parts of the organism interacts with that restricted light,
生物各个部分与限制光的相互作用
particularly by how it might cause that light to split,
特别是它如何使光束分裂 重建一个图像
we can see more of these optically anisotropic materials in action.
这样 我们能看到更多的光学各向异性材料在起作用
In our case, it often takes the form of shiny internal crystals.
在我们的例子中 它常以闪亮的内部晶体的形式展现
So we’ve given you the big overview of what these different techniques can do,
我们已向你展现了这些不同技术的大致情况
let’s go back and look at what that means for that original ciliate we started with.
让我们回过头看看这些对开篇的纤毛虫意味着什么
Here it is under brightfield microscopy.
这是它在明视场显微镜下的样子
The background is bright,
背景明亮
the image produced by changes in light amplitude
图像产生于光振幅的变化
that allow us to see the overall shape.
这使我们看到了它的整体形状
But some of the detail is hard to make out.
但还有一些细节难以辨认
Under darkfield though,
在暗视场显微镜下
the contrast increases and some of these details become more obvious,
对比度提升 一些细节变得更加明显
displaying compartments and cilia in greater detail
展现了更加细致的隔间和纤毛形态
that are also apparent under phase contrast.
这在相差显微下也十分明显
And then under polarized light,
接下来是在偏振光下的样子
the crystals that blended in with the organism previously
之前与生物混为一体的晶体
are now visible and vibrant.
现在变得可见且耀眼
Now, of course, there are many other microscopy techniques
当然 有很多其他类型的显微技术
that use light in many different ways,
它们以不同的方式利用光线
but we think it’s incredible that with just these four,
但令人难以置信的是 只用这四种技术
the world of the microcosmos looks almost like different universes,
微观世界看起来就像不同的宇宙
wrapped up into one invisible world around us.
被包裹在我们周围一个隐形的世界里
The journey, it seems, is not just about what you see,
看来 这场旅途不只是关于你看到了什么
but also how you see it.
还包括你如何去看
And ultimately,
最后 再次说明
none of these views
所有这些景象
are what the microcosmos actually looks like,
并不是微观世界真正的样子
either that, or all of them are.
不管是这个 还是所有这些
Our brains play tricks on us
大脑会蒙蔽我们
to make us believe that the world looks one way,
让我们相信世界看起来是一个样的
but the world looks different at night than in the day,
但世界在夜晚看起来和白天不一样
and both of those things have more to do with
与客观现实相比
the physiology of our eyes and our brains than with objective reality.
这些都与我们眼睛和大脑的生理机能有更大关系
Asking what a microbe actually looks like is, to some extent,
某种程度上 探究微生物真实的样子
forcing our own experience onto something that is beyond it,
是把个人经验强加于它不可及的事物上
which is not something I ever would have thought of
若非因为这个小小的油管频道
if it weren’t for this little youtube channel.
我是不会想到要观察微生物的
This is the last episode of our first season of Journey to the Microcosmos.
这是《微观旅途》第一季的最后一集
It’s been really wonderful,
真是太精彩了
and don’t worry, we’re just going to take a week off
别担心 我们只休息一周
and then we will be back with our second season,
然后 我们会带着第二季回来
featuring more of our microbial bodies and their varies antics.
重点介绍更多的微生物和它们各自不同的奇特行为
Thank you for coming on this journey with us
感谢您加入我们这场旅行
as we explore the unseen world that surrounds us.
与我们一起探索身边看不见的世界
And especially, thank you to all of these people,
特别感谢这些人员
our patrons on Patreon,
Patreon上的赞助人
who make it possible for us to take such a deep and interested look
他们让我们有机会以如此深刻有趣的方式
at this wonderful world.
看这个精彩的世界
Thank you everybody for being a part of that.
感谢每一位的参与
If you want to see more from our Master of Microbes, James,
如果你想观看更多显微镜专家James的视频
you can check out Jam and Germs on Instagram.
你可以在ins上查询Jam and Germs
And if you want to be here and ready for next season,
如果你喜欢这个节目 准备看下一季
go to YouTube.com/microcosmos
就去YouTube.com/microcosmos吧

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视频概述

本视频介绍了四种显微技术,但任何一种看到的微生物其实都不是它们真正的样子

听录译者

收集自网络

翻译译者

Felicity

审核员

审核员LJ

视频来源

https://www.youtube.com/watch?v=VBmzwM76V0o

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