Ethical dilemma: Should we get rid of mosquitoes? - Talya Hackett

翻译人员: Jacky He 校对人员: Yip Yan Yeung

Because of the pathogens they carry,

因为它们携带某些病原体，

mosquitoes are responsible for more human deaths every year than any other animal,

蚊子每年比任何其他动物， 包括人类自身，

including other humans.

造成了更多人类死亡。

But very few of the 3,500 mosquito species

但是 3,500 个蚊子品种内

actually transmit deadly diseases to humans.

很少是真正给人类 传播致命性疾病的。

So what if we could get rid of the most lethal mosquitoes?

那么如果我们能消灭 最致命的蚊子，这将怎么样？

Over the last two decades,

过去二十年以来，

scientists have begun conducting experiments using engineered technologies

科学们利用被称作 “基因驱动”的工程技术

called “gene drives” that could theoretically do just that.

展开实验， 理论上可达到这个效果。

So, should we?

那么，我们是否该这么做？

To begin grappling with this question,

若要答复这个问题，

we have to get a sense of how the technology works.

我们需要了解此技术的工作原理。

In the usual process of inheritance,

在常规的遗传步骤中，

the genomes of each parent recombine randomly.

双亲的基因组会随机重组，

So their offspring end up with the DNA that’s a rough 50/50 mix

这使得它们后代的 DNA

大约各一半分别来自双亲。

from their parents.

But gene drives thwart this process and ensure they're passed on.

但是基因驱动阻断了这个过程 并保证了某一方的完整遗传。

Gene drives are found in nature but,

基因驱动存在于大自然中，

using new gene-editing technology,

但通过新型的基因编辑技术，

scientists have also begun engineering them in contained labs.

科学家们已开始在 封闭实验室内基因改造蚊子。

For example, in a 2018 study,

比如，在一项 2018 年的研究中，

researchers injected a gene drive into mosquito eggs

研究人员将基因驱动加入蚊子卵，

that made females sterile when they had two copies of the modified gene.

并使得拥有两份 被编辑基因的雌性无法繁殖。

Such a modification would usually disappear quickly.

这样的基因改造本该很快消失，

But it spread.

但它继续扩散了。

The modified mosquitoes passed the gene drive onto some of their offspring.

基因编辑后的蚊子将基因驱动 传给了它们的一部分后代。

The gene drive, which they inherited on one chromosome,

此基因驱动，承载在一条染色体上，

copied itself onto the other chromosome in the offspring’s sperm and egg cells,

复制到后代精子卵子 细胞的其他染色体上。

ensuring it was passed on to their offspring,

这确保它会被遗传给后代，

regardless of which chromosome they received.

不论它们遗传了哪条染色体。

This process repeated as all males that carried the gene

这个过程在所有持有此基因的雄性

and all females that had one copy of it, continued reproducing,

与一份此基因的雌性 持续繁殖的途中反复上演，

spreading the gene drive.

使得基因驱动散布开来。

As they did, they produced more females that had two copies of the gene—

在这期间，它们产生了 越来越多拥有两份此基因，

and would therefore sterile.

并因此无法生育的雌性。

With a near 100% inheritance rate, the gene spread through the population

靠着接近 100% 的遗传率， 此基因在种群内扩散，

and within 12 generations almost all females were sterile,

以至于 12 代之内 几乎所有雌性无法生育，

and the populations crashed.

于是种群规模大幅下降。

In 2020, the same team achieved a similar result

在 2020 年，以上团队通过 一个基因驱动使得种群内全是雄性，

with a gene drive that made populations male-only.

从而达到类似效果。

Gene drives have proven powerful in the lab.

基因驱动在实验室内 被证实作用巨大。

So, implementing them in the wild is a big decision—

将其应用于野外 是个重要决策——

one that’s being considered because of how the fight

因对抗蚊媒疾病的现状

against mosquito-borne diseases is going.

而正被考虑。

Existing mosquito control measures, like insecticide-treated bed nets,

现存的灭蚊措施， 如含有除虫剂的蚊帐

helped reduce the number of deaths from malaria,

帮助减少疟疾导致的死亡病例；

the deadliest mosquito-borne disease, between 2000 and 2019.

疟疾是在 2000 到 2019 年间 最为致命的蚊媒疾病。

But fatalities have begun rising again.

但死亡率开始反弹。

Many mosquitoes have developed insecticide resistance—

许多蚊子进化出了除虫剂免疫，

and insecticides kill more than just mosquitoes.

而除虫剂也毒害除蚊子之外的昆虫。

In addition to the first-ever malaria vaccine,

除了第一款 于 2021 年 10 月获批的

approved in October of 2021,

疟疾疫苗之外，

many see promise in gene drives.

许多人在基因驱动中看到了希望。

Experts are researching what it would look like to specifically target

专家们正在研究将这项科技 专门针对最为致命的

the deadliest mosquito populations with this technology.

蚊子物种会怎么样。

Like Anopheles gambiae, for instance:

比如说冈比亚按蚊：

the species overwhelmingly responsible for spreading malaria in Equatorial Africa,

这个物种是在赤道非洲 传播疟疾的罪魁祸首。

which experiences the vast majority of mosquito-related fatalities.

那里出现了大量 由蚊虫导致的致死病例。

The idea is that, when a gene-drive-affected population

于是有了这样的想法： 当受基因驱动影响的

of Anopheles gambiae drops low enough,

冈比亚按蚊种群缩减到一定规模，

it would break the malaria transmission cycle.

疟疾的传染循环便会被打破。

But before gene drive mosquitoes are actually released into the wild,

但在将基因驱动的蚊子 释放到野外之前，

some big questions need answers.

尚存一些重要问题需要解答。

Like, could gene drives cross into and cause the collapse of non-target species?

比如，基因驱动个体能否会 渗透进非目标种群，使其灭亡？

It doesn’t seem that many mosquito species interbreed,

似乎较少的蚊子品种会杂交，

making this unlikely,

于是这概率较小，

but scientists are conducting research to be certain.

但科学们还在开展研究 确认这个结论。

And how might a mosquito population’s collapse affect ecosystems?

那么一个蚊子种群的灭亡 会如何影响生态系统呢？

One team is examining the feces and stomach contents

一个团队在分析加纳食虫动物的

of insectivores in Ghana to gauge the role of Anopheles gambiae in local food webs.

排泄物以及胃内容物以探究 冈比亚按蚊在当地食物网里的作用。

And researchers are investigating

并且研究人员在探究

whether suppressing populations could make other insects more vulnerable

抑制蚊子数量是否会 使得其他昆虫唇亡齿寒，

or leave a niche open that a harmful species could occupy.

或将生态位留空，引来有害物种。

Scientists are also exploring alternatives to population collapse,

科学家们还在探寻 种群灭亡的替代方案，

like gene drives that instead make mosquitoes resistant

如使蚊子对于疟原虫免疫的

to the malaria parasite.

基因驱动。

And others are developing countermeasures to reverse

另一些在研发应对措施，

the effects of gene drives if needed.

在必要时用来逆转基因驱动的影响。

Meanwhile, some people have called for gene drive research to halt

同时，部分人希望 停止基因驱动的研究，

out of concern for the possible consequences.

出于对潜在后果的顾虑。

This raises another question: who should decide whether to release gene drives?

这带来了另一个问题： 谁来决定是否该释放基因驱动？

那些尤其受蚊媒疾病所扰的国家的

It’s essential that communities, scientists, regulators,

and governments of the countries most affected by mosquito-borne diseases

社区、科学家、管理部门和政府

be highly involved in the research and decision-making processes.

很有必要深入参与研发与决策过程。

Conversations are currently underway at all levels

目前，各个层面的谈话正在展开，

to establish a system to manage this new area of research—

以建立一个系统来管理 这个全新的研究领域——

and the ethical questions it carries.

以及随之而来的伦理问题。