基因工程与疾病——基因驱动与疟疾：英语精读讲义

What if you could use genetic engineering to stop humanity's most dangerous predator? 語法

如果你能用基因工程阻止人类最危险的天敌，那会怎样？

The deadliest animal on the planet responsible for the death of billions,

这个地球上最致命的动物造成了数十亿人的死亡，

the mighty mosquito.

它就是强大的蚊子。

Along with other diseases,

除了其他疾病，

it plays host to malaria, 短語搭配

它还是疟疾的宿主，

one of the cruelest parasites on Earth,

这是地球上最残酷的寄生虫之一，

possibly the single biggest killer of humans in history.

甚至可能是历史上杀人最多的人类杀手。

In 2015 alone,

仅在 2015 年，

hundreds of millions were infected and almost half a million people died.

就有数亿人被感染，近五十万人死亡。

A new technology could help us eradicate malaria forever.

一项新技术可能帮助我们永远消灭疟疾。

But to do so,

但要做到这一点，

we need to engineer a whole animal population.

我们需要改造整个动物种群。

This is not a hypothetical problem.

这不是一个假设性的问题。

The modified mosquitoes already exist in a lab.

经过改造的蚊子已经存在于实验室中。

Should we use the technology?

我们应该使用这项技术吗？

And is malaria bad enough to risk it? 語法

疟疾是否严重到值得我们去冒险？

Malaria is caused by a group of microorganisms,

疟疾是由一组微生物引起的，

Plasmodia.

即疟原虫 (Plasmodia)。

Very weird microorganisms that consist of just a single cell.

这是非常奇怪的微生物，仅由单细胞组成。

They're parasites that completely rely on mosquitoes. 短語搭配

它们是完全依赖蚊子的寄生虫。

Malaria always starts with an insect bite.

疟疾总是从被蚊虫叮咬开始的。

In its salivary glands,

在其唾液腺中，

thousands of sporozoites wait until the insect penetrates your skin.

成千上万的子孢子等待着，直到这只昆虫刺穿你的皮肤。

Immediately after invading you,

在侵入你体内后，

they head for the liver, 短語動詞

它们立即前往肝脏，

where they quietly enter big cells and hide from the immune system.

在那里它们悄悄进入大细胞并躲避免疫系统。

For up to a month,

在长达一个月的时间里，

they stay here in stealth mode,

它们在这里保持潜行模式，

consuming the cells alive and changing into their next form,

活生生地吞噬细胞并变成它们的下一种形态，

small drop-like merozoites.

小水滴状的裂殖子。

They multiply,

它们开始繁殖，

generating thousands of themselves and then burst out of the cells. 短語動詞

生成数千个自身的复制体，然后突破细胞而出。

So thousands of parasites head into the bloodstream to look for their next victims,

于是，成千上万的寄生虫进入血液寻找它们的下一个目标，

red blood cells.

即红细胞。

To stay unnoticed,

为了不被发现，

they wrap themselves in the membranes of the cells they killed.

它们用被自己杀死的细胞的细胞膜把自己包裹起来。

Imagine that.

想象一下。

Killing someone from the inside and then taking their skin as camouflage.

从内部杀死某人，然后拿他们的皮肤当作伪装。

Brutal.

极其残忍。

They now violently attack red blood cells,

现在，它们疯狂攻击红细胞，

multiplying inside them until they burst,

在红细胞内繁殖直到细胞破裂，

then finding more red blood cells,

然后寻找更多的红细胞，

and this cycle repeats over and over. 短語搭配

这个循环一遍又一遍地重复。

Pieces of dead cells spread lots of toxic waste material,

死亡细胞的碎片散布出大量有毒废物，

which activates a powerful immune response,

这会激活强烈的免疫反应，

causing flu-like symptoms. 用詞

引起类似流感的症状。

Among the symptoms are high fever,

症状包括高烧、

sweats and chills,

盗汗和发冷、

convulsions, headaches,

抽搐、头痛，

and sometimes vomiting and diarrhea.

有时还有呕吐和腹泻。

If malaria breaches the blood-brain barrier, 用詞

如果疟疾突破了血脑屏障，

it can cause coma,

可能会导致昏迷、

neurological damage,

神经损伤，

or death.

甚至死亡。

The parasites are ready for evacuation now.

寄生虫现在准备好撤离了。

When another mosquito bites the infected human,

当另一只蚊子叮咬了受感染的人时，

they get a ride. 習語

它们便搭上了顺风车。

The cycle can start over.

循环又可以重新开始了。

In 2015,

2015 年，

the Zika virus,

寨卡 (Zika) 病毒——

which causes horrible birth defects if it infects pregnant women,

如果感染孕妇会导致可怕的出生缺陷——

spread rapidly into new areas around the globe.

迅速蔓延到全球的新地区。

It too is carried by a mosquito.

它也是由蚊子携带的。

The mosquito is the perfect carrier for human diseases.

蚊子是人类疾病的完美载体。

They've been around for at least 200 million years.

它们已经存在了至少两亿年。

There are trillions of them,

它们的数量数以万亿计，

and a single one can lay up to 300 eggs at a time. 短語搭配

且单只蚊子一次就能产下多达 300 枚卵。

They are practically impossible to eradicate

它们几乎是不可能被根除的，

and the perfect parasite taxi. 習語

是完美的“寄生虫出租车”。

But today,

但今天，

we have a new revolutionary technology that could enable us to finally win the war against them. 習語

我们拥有了一项新的革命性技术，或许能让我们最终赢得与它们的战争。

CRISPR.

也就是 CRISPR。

For the first time in human history, 短語搭配

在人类历史上，我们第一次

we have the tools to make fast,

拥有了可以快速、

large-scale changes to entire species,

大规模改变整个物种的工具，

changing their genetic information as we please. 短語搭配

能随心所欲地改变它们的遗传信息。

So, instead of attacking isolated groups of insects, 語法

那么，与其攻击孤立的昆虫群体，

why not just change the types that transmit diseases? 語氣意圖

为什么不直接改变传播疾病的种类呢？

Using genetic engineering,

科学家们利用基因工程，

scientists successfully created a strain of mosquitoes that are immune to the malaria parasite 短語搭配

成功创造出了一种对疟原虫免疫的蚊子品种，

by adding a new antibody gene that specifically targets Plasmodium.

做法是添加一种专门靶向疟原虫的新抗体基因。

These mosquitoes will never spread malaria.

这些蚊子将永远不会传播疟疾。

But just changing genetic information is not enough. 語法

但仅仅改变遗传信息是不够的。

The edits would only be inherited by half the offspring

这种编辑只会被一半的后代遗传，

because most genes have two versions inside the genome as a failsafe. 用詞

因为大多数基因在基因组内有两个版本，作为一种安全机制。

So, after just two generations,

所以，仅仅过了两代之后，

at most only half of the offspring would carry the engineered gene.

最多只有一半的后代会携带这种经过设计的基因。

In a population of billions of mosquitoes,

在数十亿只蚊子的种群中，

they would hardly make a difference. 短語搭配

它们几乎不会产生什么影响。

A genetic engineering method called the gene drive solves this problem. 文化背景

一种被称为基因驱动 (gene drive) 的基因工程方法解决了这个问题。

It forces the new gene to become dominant in the following generations,

它迫使新基因在后代中成为显性，

overpowering the old gene almost completely.

几乎完全压倒了旧基因。

Thanks to this twist, 表達脈絡

多亏了这个巧妙的机制，

99.5% of all the engineered mosquitoes offspring

在所有经过基因改造的蚊子后代中，99.5% 的个体

will carry the anti-malaria edit.

将携带抗疟疾的编辑基因。

If we were to release enough engineered mosquitoes into the wild 語法

如果我们在野外释放足够多的基因改造蚊子，

to mate with normal mosquitoes,

让它们与正常蚊子交配，

the malaria-blocking genes would spread extremely quickly.

阻断疟疾的基因就会极其迅速地传播。

As the new gene becomes a permanent feature of the mosquito population,

随着新基因成为蚊子种群的永久特征，

Plasmodium would lose its home base. 習語

疟原虫将失去它的大本营。

Scientists hope that the change would be so fast 語法

科学家们希望这种变化会非常快，

that they could not adapt to it quickly enough.

快到它们无法及时适应。

Malaria could virtually disappear.

疟疾可能就会真正销声匿迹。

If you take into account that maybe half a million children are killed by it every year, 短語搭配

如果你考虑到每年可能有 50 万名儿童死于这种疾病，

about five have died since this video started,

自本视频开始以来，大约已有五个孩子死去了，

some scientists argue that we should use the technology sooner rather than later. 習語

一些科学家认为，我们应该尽早使用这项技术。

The mosquitoes themselves would probably only profit from this.

蚊子本身大概也能从中获益。

They don't have anything to gain from carrying parasites. 短語搭配

携带寄生虫对它们没有任何好处。

And this might only be the first step.

这也许仅仅是第一步。

Malaria might just be the beginning.

疟疾可能只是个开始。

Different mosquitoes also carry dengue fever and Zika.

不同的蚊子还携带登革热和寨卡病毒。

Ticks transmit Lyme disease.

蜱虫传播莱姆病。

Flies transmit sleeping sickness.

苍蝇传播睡眠病。

Fleas transmit the plague.

跳蚤传播鼠疫。

We could save millions of lives and prevent suffering on an unbelievable scale.

我们可以拯救数百万人的生命，并防止难以想象的苦难。

So, why haven't we done this yet? 表達脈絡

那么，为什么我们还没有这么做呢？

For one, CRISPR editing is barely four years old. 講解

首先，CRISPR 编辑技术面世还不到四年。

So, until very recently,

所以直到最近，

we just couldn't do it as fast and easily.

我们还无法如此快速、轻松地进行这种操作。

And there are valid concerns.

而且人们有合理的担忧。

Never before have humans consciously changed the genetic code of a free-living organism on this scale. 語法

人类以前从未在这个规模上有意识地改变过一种自由生存生物的遗传密码。

Once we do it, there is no going back. 習語

一旦我们这么做了，就没有回头路了。

So, it has to be done right

因此，必须谨慎行事，

because there could be unwanted consequences if we set out to edit nature. 短語動詞

因为如果我们着手编辑自然，可能会产生意想不到的后果。

In the specific case of malaria, though, 表達脈絡

不过，在疟疾的具体案例中，

the risk might be acceptable since the genetic modification doesn't make a big change in the overall genome.

风险也许是可以接受的，因为这种基因改造不会对整个基因组造成重大改变。

It only changes a very specific part.

它只改变了一个非常特定的部分。

The worst-case scenario here is probably that it might not work 短語搭配

这里最糟糕的情况，大概就是它可能不起作用，

or that the parasite adapts in a negative way.

或者寄生虫以一种负面的方式去适应它。

There is still much debate.

争论仍在继续。

Technology as powerful as gene drive needs to be handled with a lot of care. 講解

像基因驱动这样强大的技术，需要非常谨慎地处理。

But at some point,

但在某些时候，

we have to ask ourselves, 短語搭配

我们必须问自己，

is it unethical to not use this technology

当每天有 1,000 名儿童死亡时，

when every day 1,000 children die?

不使用这项技术是否才是不道德的？

Humanity has to decide how to act on this in the next few years. 短語動詞

人类必须决定在未来几年内如何应对这一问题。

The public discussion is way behind the technology in this case. 用詞

在这个案例中，公众的讨论远远落后于技术的发展。

What do you think?

你怎么看？

This video was made possible in part by viewer donations on Patreon. 短語搭配

本视频的部分制作经费来源于观众在 Patreon 上的捐款。

If you want to help us make more videos like this and get nice rewards in return, 短語搭配

如果你想帮助我们制作更多类似的视频并获得丰厚的回报，

you can do so here.

你可以在这里赞助。

We really appreciate it.

我们非常感谢。

If you want to learn more about the topic of genetic engineering,

如果你想了解更多关于基因工程的话题，

we have another video about CRISPR and GMOs.

我们还有另一个关于 CRISPR 和转基因生物 (GMOs) 的视频。

And in case that's too much biology for you, 語法

如果这对你来说生物学知识太多了，

here's a space playlist.

这里有一个关于太空的播放列表。