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完全不需要氧气的生命体 – 译学馆
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完全不需要氧气的生命体

Life Without Oxygen? Challenge Accepted

《微观旅途》
So far, as we’ve journeyed through the microcosmos,
迄今为止 在我们的微观旅途中
the organisms we’ve shown you are mostly aquatic.
我们向您展示的生物大部分是水生的
You might find them in oceans or rivers or lakes,
你或许能在江河湖海中发现它们
finding their own niche in their watery ecosystem.
它们在水生生态系统中找到了自己的安身之处
And surrounding them, dissolved in the water, is always oxygen,
它们周围的水中 一直都含有氧气
which is essential to their survival.
它们的生存离不开氧气
But as you travel down and find where water meets sediment,
但当你下沉到水和沉积物的交汇处
a transition occurs.
一个转变发生了
Yes, from more liquid to more solid,
没错 从偏液态转向偏固态
but more importantly,
但更重要的是
the sediments impede the movement of oxygen.
沉积物阻碍了氧气的流动
Which means that, as oxygen gets consumed by living organisms,
这也就意味着 随着生物消耗氧气
the concentration goes down.
氧气的浓度会下降
The transition here is, in many ways,
这种转变 在很多方面
even more distinct than the transition
甚至比宏观世界中
from land to the sea in our macro-world.
从陆地到海洋的转变更为显著
Yes, it is difficult for fish to live out of water,
没错 鱼儿离开水难以存活
and hard for us to live in it.
人类难以在水中生存
but ultimately, fish and humans
但归根结底 鱼和人类
are both based on roughly the same metabolic chemistry.
都是基于大致同一种代谢化学
We both rely on oxygen.
我们都依赖氧气
But here at this transition,
然而此处的转变
where the environment goes from oxic, meaning there is oxygen, to anoxic, meaning there isn’t,
环境从有氧(指含有氧气)变为缺氧 (指缺乏氧气)
life’s metabolic chemistry fundamentally shifts.
生命的代谢化学从根本上改变了
It’s muddy there. It’s slimy, a little smelly,
这儿泥泞 黏糊 有点臭烘烘
maybe even a little gross,
甚至可能还有点恶心
but to many organisms,
但是对很多生物而言
the oxic anoxic transition is a shifting chemical boundary
这种有氧到缺氧的转变是游移的化学边界
that has created a challenge for life…
其带来了生存的挑战……
a challenge that changed it’s nature,
带来了生物改变天性
a challenge it conquered.
和需要攻克的挑战
So let’s talk about the organisms that prefer an environment void of oxygen,
让我们来谈谈那些喜欢无氧环境的生物
because many of them will end up shaping the world
因为 对于生活在有氧向无氧转变中的生物来说
around the organisms that live along this transition.
很多喜欢无氧环境的生物 最终会影响其周围的世界
Now we’re not quite sure,
虽没有十分把握
but we believe this long, large, tightly-coiled bacterium
但是我们认为这种又长又大 紧密缠绕的细菌
is a type of spirochete,
是一种螺旋菌
many of which prefer to live without oxygen.
其中很多喜欢在无氧的环境下生活
They come up often in these mud samples
它们经常出现在这些泥水样本中
and you might know some of their kind as the more familiar, and less welcome organisms
你可能听说过某些更为人熟知却不受欢迎的种类
that cause syphilis and Lyme disease.
那就是导致梅毒和莱姆病的螺旋体
And just to note, this video is not sped up
要注意的是 这个视频并没有加速
—the organism really moves like this.
这些生物就是这样移动的
Spirochete’ are uniquely motile,
螺旋体具有无与伦比的活动力
able to move around even in thick, viscous substances.
即使在厚重粘稠的物质中也能移动
To vastly oversimplify the entire basis of our life
众所周知 我们生命的整个基础
as we know it,
简而言之就是:
oxygen’s big, important role is to accept electrons in the chemical processes
氧的重要作用是在化学过程中接受电子
that make our cells go
使我们的细胞得以运作
and our existence possible,
使我们的存在成为可能
so, thanks oxygen.
确实 要感恩氧气
But organisms that live in anoxic environments
但是生活在缺氧环境中的生物
substitute oxygen with other chemicals.
它们用其他化学物质来代替氧气
Some, like this ciliate Caenomorpha,
有些 比如像这个异毛目水母虫
are found in environments rich in
是在富含硫的环境中被发现的
oxygen’s downstairs neighbor on the periodic table, sulfur,
化学元素周期表中 硫位于氧的下方
along with bacteria that thrive in a sulfuric world.
一起被发现的 还有在硫环境繁荣生息的细菌
Now these look like vibrating, hyperactive worms,
这些看上去像是不停振动 极度活跃的虫子
but they’re actually bacteria,
但它们实际上是细菌
specifically a purple sulfur bacteria, these are Thiospirillum.
明确点说是紫硫菌 属于硫螺旋菌
Inside the Thiospirillum are little globules
硫螺旋菌的内部有一些小球体
where they stock sulfur for later use.
其中储存着硫 供日后使用
They’re photosynthetic
硫螺旋菌可以进行光合作用
and they often prefer anoxic environments.
它们通常更喜欢缺氧环境
These bacteria use various forms of sulfur to produce their energy
这些细菌利用各种形式的硫来产生能量
—including, in the case of thiospirillum, those sulfur stores.
包括硫螺旋菌的这种储存形式的硫
In these kinds of sulfuric sediments,
在这些含硫沉积物中
you’ll find concentrations of sulfur and oxygen as opposing gradients.
你会发现硫和氧的浓度梯度是相反的
As you descend into sediment,
当下降到沉积物中
the concentration of oxygen decreases, consumed by the life that depends on it.
氧气的浓度会由于被生物消耗而降低
Meanwhile, sulfide diffuses upwards from the anoxic microbes below,
同时 硫化物从下面的厌氧微生物向上扩散
and as you travel further down, the sulfur concentration increases
越往下 硫的浓度越高
as you get closer to its source.
因为越接近它的源头
But in that sediment
但是在沉积物中
is a layer where oxygen and sulfur co-exist.
有一层是氧和硫共存的
This is the oxic-anoxic interface,
这是有氧和缺氧的交界处
a several 100 uM thick boundary
一个几百微米厚的分界
that attracts bacteria like these Achromatium oxaliferum,
它会吸引像草酸无色菌之类的细菌
a large sulfur bacteria
草酸无色菌是一种大型硫细菌
found in freshwater and salt marsh sediments
被发现于淡水和盐沼沉积物中
that comes up often in our mud samples.
经常出现在我们的泥水样本中
Similar to Thiospirillum, Achromatium has small sulfur globules.
类似硫螺旋菌 无色菌也有含硫小球体
But the bacteria is also able to roll upwards through the sediment in
但这种细菌也能在沉积物中向上滚动
what seems to be a response to the presence of oxygen,
这似乎是对氧气存在的一种反应
suggesting that it might take up oxygen as well.
表明它可能也会摄取氧气
Currents in the water and various other changes in the environment
水流和各种其他环境变化
can affect where the oxic-anoxic interface is,
可以影响有氧缺氧交界层
so Achromatium and other bacteria that thrive in this layer
所以在交界层繁荣生息的无色菌和其他细菌
need the ability to sense and move
需要具备感知和移动的能力
in response to the shifting oxygen and sulfur layers.
以应对氧和硫层的变化
These gradient roving Achromatium
这些以梯度移动的无色菌
have so far been difficult to grow in large quantities in a lab,
目前为止很难在实验室里大量生长
perhaps because their natural environment
也许是因为它们的自然环境
and the relationships they have with their surrounding microbes are just too complicated.
还有它们与周围微生物的关系太复杂了
As a result, these bacteria remain mysterious giants.
因此 这些细菌仍旧是神秘的大型菌
Their bodies contain sizable stores of calcite,
它们体里含有大量的钙
but we don’t know what they’re for.
但是我们尚不知晓那有什么用
Some scientists have guessed that they might help control the acidity of the cell,
一些科学家猜测它们可能有助于控制细胞的酸度
while others have suggested it might help regulate the cell’s buoyancy.
而其他人则认为它或许能帮助调节细胞的浮力
There are many theories, including
关于这点有很多学说 其中包括
that the amount of calcite inside Achromatium makes them off-putting to predators.
无色菌体内的钙含量能使其捕食者反感
Now, we don’t know if that’s the case with this Loxodes magnus,
我们不知道这个大喙纤虫是否面临这种情况
which is valiantly trying and failing to eat this Achromatium.
它正勇猛地试图捕食这个无色菌 然而失败了
We did observe it for a while,
我们确实观察了好一会儿
and it kept rejecting the giant bacterium,
它一直拒绝进食这个大型菌
so at the very least, there seems to be something unappetizing about them.
最终 似乎有某些东西倒它的胃口
Here with some Achromatium,
这儿和无色菌在一起的家伙
is a fellow interface bacteria Macromonas,
是交界层的细菌 叫做大单胞菌
moving around with the use of its flagella.
它正利用鞭毛四处移动
Macromonas seem to also keep a sulfide stock in little globules,
大单胞菌似乎也在小球体中储存硫
and they’re distinguished by inclusions where they store calcium oxalate,
区别在于它们的内含物中还储存草酸钙
which may help the cell keep up its metabolism
它可能有助于细胞即便在不佳的周边环境下
even when the conditions around it aren’t good.
仍然维持自身的新陈代谢
You can see the inclusions in this clip here—
你可以在这段剪辑视频中看到它的内含物
the larger those calcium oxalate stores are,
草酸钙的储存量越大
the slower the bacteria moves.
细菌移动地越慢
There is, of course, so much more to the story of mud and microbes.
当然 关于泥土和微生物的故事还有很多
The oxidations and the reductions.
氧化和还原
The various forms of the sulfurs and the oxygens,
硫和氧的各种形式
not to mention the carbons and nitrogens that…we did not even mention.
更不用说碳和氮了……我们甚至都没提过
It’s messy, and we don’t mean muddy…we mean, complicated.
它很乱 不是指脏乱……而是说 复杂
As you might have noticed,
你可能已经注意到
oxygen is pretty important to biochemical mechanisms.
氧对生化机制非常重要
We can live weeks without food,
缺少食物 我们仍能存活数周
days without water,
没有饮水 能存活数天
but only moments without oxygen.
但是没了氧气 生命只能存在片刻
And metabolic systems on this planet evolved largely
这一神奇 广泛 普遍的电子接受体
in the presence of this
它的存在
marvelous, versatile, and common electron acceptor.
使这个星球上的新陈代谢系统有了重大的进化
Without it, everything changes.
没有氧气 万物将会改变
Every balance has to be re-weighted.
一切平衡须重新调整
Every gradient shifted.
一切梯度势必变动
And yet when you step back and look at these anoxic environments,
当你退后一步来审视这些缺氧的环境
everything seems to come together in a muddy elegance.
一切似乎都以一种朦胧的优雅结合在一起
One gradient gives way to another, one process swaps out for another.
其梯度与过程总是迭代更新
And the microcosmos distributes itself accordingly.
微观世界的分布也与之相呼应
Thank you for coming on this journey with us as we explore the unseen world that surrounds us.
感谢你和我们一起踏上探索周围未知世界的旅途
Journey to the Microcosmos is produced by Complexly.
《微观旅途》由Complexly制作
If you want to keep imagining the world complexly with us,
如果你想了解更多complexly
we have a bunch of other things.
我们还有很多其他节目
We’re producing a Crash Course on Artificial Intelligence right now, hosted by Jabril Ashe.
我们正在制作由Jabril Ashe主持的人工智能的闪课
Over 20 episodes,
在二十多集课程中
we’ll going to unpack the logic behind AI systems,
我们将会解开人工智能系统背后的逻辑
and even write and implement code in labs.
甚至在实验室编写和实践代码
Check out the first video
请点击收看第一集
about the history of artificial intelligence and the revolution that is happening today!
关于人工智能的历史以及当今正在发生的变革
There’s a link in the description.
请点击下方链接
If you want to see more from our master of microscopes James
如果你想观看更多《显微镜大师詹姆斯》的节目
check out Jam and Germs on Instagram.
请在Instagram关注Jam and Germs
And if you want to see more from us,
如果你想观看更多我们的节目
there’s always a subscribe button somewhere nearby.
请点击订阅按钮

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视频概述

氧气对生命无疑是至关重要的。但是也有某些生物,可以在缺氧环境下生存。

听录译者

收集自网络

翻译译者

zbz

审核员

审核员SR

视频来源

https://www.youtube.com/watch?v=H8b09C1WPQk

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