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鲑居尾孢虫—唯一不利用氧气呼吸的动物 – 译学馆
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鲑居尾孢虫—唯一不利用氧气呼吸的动物

The Only Animal That Can't Breathe Oxygen

There are a few things in life that we, as animals,
生活中有些东西 如作为动物的我们
absolutely cannot live without.
是绝对离不开的
One of those things is oxygen.
其中一个就是氧气
It’s so essential that every multicellular species we’ve ever studied
它十分重要 我们知道的所有多细胞生物
has the ability to use oxygen to create energy.
都能够利用氧气创造能量
That is, every species except one.
然而 有个物种例外
Because in 2020, biologists reported that they’d found an animal
因为在2020年 生物学家表示他们发现一种动物
that not only doesn’t breathe oxygen
不仅不需要氧气
as far as they could tell, it can’t.
据他们说 它们无法利用氧气
This species is called Henneguya salminicola,
这个物种名叫鲑居尾孢虫
because it infects salmon during a couple of stages of its development.
因为在鲑鱼发育的几个过程中会感染上它
It’s a type of animal called a myxozoan,
它是一种粘原虫
making it a sort of tiny parasitic jellyfish with a complex life cycle.
是具有复杂生命周期的微小寄生水母
We know it spends part of its time in salmon,
我们知道 它有段时间在鲑鱼身上度过
but not where it goes after that.
但不知道之后它去了哪里
And it doesn’t seem to have much in the way of mitochondria.
它似乎没有线粒体
Say it with me, now: Mitochondria are the powerhouses of the cell.
现在 跟着我说: 线粒体是细胞的发电厂
They take sugars and oxygen
它们摄入糖类和氧气
and turn them into the molecules that carry energy.
然后将它们转化为携带能量的分子
All eukaryotic life, everything with a nucleus,
所有真核生物 所有具有细胞核的生物
both single-celled and multicellular,
不论多细胞还是单细胞生物
has these in its evolutionary history.
在进化历程中都有这些
Even life forms that have adapted to oxygen-poor environments
即使是适应了缺氧环境的生物
tend to hold onto some version of their mitochondria.
也会保留某种形式的线粒体
And all animals have some capacity
所有动物都有一定的
to use their mitochondria to metabolize oxygen.
利用线粒体代谢氧气的能力
Even though they live inside other cells,
即使它们位于另一个细胞里
mitochondria have their very own genomes
线粒体有自己的基因组
called mitochondrial or mtDNA.
称为线粒体DNA
In this study, published in the journal PNAS,
在这项发表在PNAS杂志上的研究中
researchers were trying to compare the mitochondrial genomes
研究人员试图比较
of H. salminicola and another, closely-related species.
鲑居尾孢虫和另一亲缘物种的线粒体DNA
Except they discovered that… they couldn’t.
但他们发现….他们没法比较
Because H. salminicola didn’t seem to have mtDNA
因为鲑居尾孢虫似乎没有线粒体DNA
something we’ve never confirmed in a multicellular organism before.
我们过去从未在多细胞生物中发现过(这种DNA)
DNA, both mitochondrial and regular,
DNA 不论线粒体DNA还是常规DNA
is what tells a cell how to make different proteins.
都指导着细胞该如何合成不同的蛋白质
And without mtDNA, this parasite is missing the instructions
没有线粒体DNA 这种寄生虫就失去了合成
to make proteins it would need to turn oxygen into energy.
将氧气转换为能量所需蛋白质的指令
The team was understandably intrigued,
研究小组对此很感兴趣
and they decided to look at its regular DNA, too.
决定再研究下它的常规DNA
Specifically, they were looking for genes that we know help mitochondria
特别是寻找我们所知道的帮助线粒体将氧气
turn oxygen into energy,
转化为能量的基因
some of which are in the regular genome
这些基因有的在常规基因组
rather than the mitochondrial one.
而不是在线粒体基因组中
And H. salminicola only had 7,
鲑居尾孢虫只有7个
while other myxozoans usually have
而其他粘原虫类通常
somewhere between 18 and 25.
在18到25个之间
These guys still have structures similar to mitochondria,
这些家伙仍然有类似线粒体的结构
called mitochondria-related organelles.
称为线粒体相关细胞器
And these structures probably do help with energy production.
这些结构可能有助于能量的供给
Just… not from oxygen.
只是…并非通过氧气罢了
So why’d our salmon-infecting friend
不过为什么鲑鱼寄生朋友
toss its ability to use oxygen out the window?
会舍弃利用氧气的能力呢?
It lives in an oxygen-poor environment anyway,
它生活在缺氧的环境中
such as… inside a salmon.
比如… 生活在鲑鱼体内
So it must get its energy through less efficient,
因此 它必须通过低效率 不依赖氧气
oxygen-independent means
的方法来获取能量
specifically, by breaking down sugars without oxygen.
特别是在无氧的情况下分解糖
Life that does breathe oxygen, like us, can also break down sugars this way,
像我们这样呼吸氧气的生命也可以这样分解糖
but you get much less energy out of it.
只是从中得到的能量要少得多
We know that when genes go unused for many generations,
我们知道 当基因在很多代都不被使用时
they can simply… be lost.
很可能会…… 丢失
In the case of this parasite,
对于这种寄生虫而言
losing its mtDNA could be an evolutionary adaptation.
丢失线粒体DNA可能是进化适应
It takes energy to maintain genes.
维持基因需要能量
And especially in a creature with a tiny genome like H. salminicola,
尤其是像鲑居尾孢虫这样的小基因组生物
losing DNA that it wasn’t using anyway
丢失它无论如何都不会用到的DNA
could have saved energy it could otherwise use to survive.
可以节省原本可以用于生存的能量
Or something similar could have happened as a fluke.
也可能是发生了类似的偶然事件
Natural selection can drive genetic change,
自然选择可以造成基因转变
but so can pure random chance.
而单纯的变异也可以
The team points out
研究小组指出
that besides revealing the first known animal to not breathe oxygen,
除了揭示了首个已知的不呼吸氧气的动物外
this discovery could also be useful on a practical level.
这个发现在实践层面也很有用
This myxozoan parasite can actually be a big problem for salmon farmers,
这种粘原寄生虫对鲑鱼养殖户来说其实是个大问题
and knowing that is doesn’t breathe oxygen
知道它不呼吸氧气
could help us make drugs that are better at targeting it.
有助于我们设计出针对它的特效药物提供帮助
So maybe it wasn’t that great a trick, after all.
所以到头来 这并不是什么好把戏
Thanks for watching this episode of SciShow, which is produced by Complexly.
感谢收看由Complexly制作的这期科学秀
If you like learning about super small stuff,
如果你喜欢研究微生物
we think you’ll really like our sister channel, Journey to the Microcosmos.
我认为你会非常喜欢我们的姐妹频道《微观世界之旅》
The show’s whole MO is slow, calming descriptions of microscopic life,
节目整体是对微观生活缓慢 平静的描述
paired with fantastic microscopy and soothing music.
配上美妙轻柔而舒缓的音乐
It’s what we all deserve right now.
正是目前我们所需要的
Check it out at the link in the description!
点击视频描述中的链接即可获取

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视频概述

最新发现一种不需氧气生活的多细胞生物,究竟是怎么回事,我们一起来一探究竟吧!

听录译者

收集自网络

翻译译者

九月

审核员

审核员 V

视频来源

https://www.youtube.com/watch?v=3fJCdtiscEA

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