Axolotls: The salamanders that snack on each other (but don't die) - Luis Zambrano

翻译人员: Carol Wang 校对人员: Helen Chang

In 1864, French zoologist August Duméril

1864 年，法国动物学家 August Duméril

was baffled while investigating the axolotl.

在研究蝾螈时感到困惑不解。

Unlike many other amphibians, which transform into terrestrial adults,

与成年后变成陆地生活的 其它两栖类动物不同，

axolotls retain their juvenile characteristics and never leave the water.

美西螈一直保持青少年特征， 而且从不离开水。

In an attempt to induce metamorphosis,

为了诱导它们变形，

Duméril spent months removing their gills.

Duméril 花了几个月的时间 切除它们的鳃。

But in most instances, the axolotls simply... grew them back.

但多数情况下， 美西螈很快又长出了鳃。

Indeed, axolotls are masters of regeneration:

的确，美西螈是再生大师：

they can flawlessly regenerate body parts

它们能完美地长出身体部位，

ranging from amputated limbs and crushed spines to parts of their eyes and brains.

从断肢、脊椎到部分眼睛和大脑。

So how do they do it? And what other secrets are they keeping?

那它们如何做到的呢？ 它们还有哪些秘密呢？

This extraordinary salamander is native to the wetlands in Mexico City.

这种奇特的蝾螈的栖息地 是墨西哥城的湿地，

Ancient Aztec people considered it the incarnation of a God named Xolotl—

古代阿兹特克人认为 它是名为 Xolotl 的神的化身——

hence the axolotl’s name, roughly meaning “water monster.”

名称美西螈（Axolotl）由此而来， 意思大致是“水怪”。

Axolotls reach sexual maturity with gills and a tadpole-like dorsal fin.

长出鳃和蝌蚪状的背鳍后， 美西螈达到性成熟。

Scientists think their forever-young condition, called “neoteny,”

科学家们认为，这种 “幼态化”的永远年轻状态，

evolved because of their stable habitat.

是因为栖息地稳定的进化结果。

For salamanders that develop in waters that dry up,

对生活在会干涸水域的蝾螈来说，

efficiently transitioning to land is essential.

有效转移到陆地生活至关重要。

But the lakes axolotls evolved in were unchanging year-round

但美西螈演化所处的湖泊终年不变，

and didn't host many aquatic predators.

而且湖里没有太多的水生捕食者。

So, scientists think it was advantageous for axolotls

因此，科学家们认为

放弃变形的需求有利于美西螈，

to forgo the demands of metamorphosis.

However, they haven’t completely lost this ability.

然而，它们并非完全丧失变形能力。

If exposed to certain substances, axolotls will turn into adults.

如果暴露在某些物质中， 美西螈会变为成年，

But they’ll often experience shorter lifespans

但经常寿命较短，

and lose some of their self-healing abilities.

也丧失一些自我修复能力。

These regenerative talents may seem like crazy superpowers to begin with,

这些再生才能可能一开始 看起来像超棒的超能力，

but axolotls have good use for them.

但美西螈善用了它们。

As babies, they’re in direct competition.

在婴儿期，它们就处于直接竞争中，

So, they snack on each other.

所以，它们会吃对方。

This is usually not a huge problem thanks to how quickly

这通常不是一个大问题，

they can regenerate body parts.

因为它们的身体器官 再生速度非常快。

When an axolotl loses a limb, tissues stimulate growth in the area.

当美西螈失去肢体时， 组织会刺激该区域的生长。

Skin cells divide and cover the wound.

皮肤细胞分裂并覆盖住伤口，

Then, progenitor cells, which can develop into various bodily tissues,

接着，祖细胞在受伤部位形成团块，

form a mass at the site of injury

祖细胞能发展成各种身体组织，

and nearby nerves secrete growth-promoting proteins.

且附近神经分泌出促生长蛋白质。

Over the next few weeks, a new limb emerges

接下来的几周里， 随着细胞的增殖和分化，

as cells proliferate and differentiate in coordination.

一个新的肢体出现了。

This process could potentially lead to uncontrolled growth and tumor formation.

这一过程可能导致 不可控生长和肿瘤的形成，

But axolotls are remarkably resistant to cancer.

但美西螈对癌症有很强抵抗力，

They have a system in place that tightly controls cellular proliferation.

它们有一个严格控制 细胞增殖的系统。

To better understand the axolotl’s baffling biology,

为更了解美西螈 令人困惑的生物学特性，

scientists sequenced its genome.

科学家们对其基因组进行了测序，

They found it to be more than ten times longer than a human’s.

发现比人类的长十倍以上。

Mutations can change the length of any animal’s genome.

突变可改变任何动物基因组的长度。

For whatever reason, salamanders have much more DNA than other vertebrates

不管什么原因，蝾螈 比其他脊椎动物拥有更多 DNA，

because they lose parts of it less frequently.

因为它们不那么频繁地失去一部分。

Investigating the axolotl’s genome, scientists saw many repeated sequences,

研究美西螈的基因组时， 科学家发现了许多重复序列，

most of which don't code for proteins and have no known function.

其中大多数不编码蛋白质， 也不知其功能是什么。

They also found genes that are key in regeneration.

他们还发现了再生的关键基因，

However, the biggest factor that sets axolotl regeneration apart

但美西螈与众不同的再生最大因素 可能不是一组独特的基因，

may not be a set of unique genes, but how they regulate their genes.

而是它们如何调节自己的基因，

It’s no wonder that axolotls are one of science’s most studied animals.

难怪美西螈是科学界 研究最多的动物之一。

But their population in the wild has plummeted.

但它们在野外的数量急剧下降，

Hundreds of years ago, axolotls thrived under the Aztec capital.

几百年前，美西螈 在阿兹特克首府繁荣起来，

Within the surrounding lakes,

在周围的湖泊中，

Aztec people built islands called chinampas for growing crops.

阿兹特克人建造了 奇南帕浮田岛来种植庄稼。

This highly productive form of agriculture created a vast system of canals,

这种高产农业形式 创造了巨大的运河系统，

expanding the lake system’s shallow, sheltered habitat—

拓展了有庇护的湖泊浅水区栖息地

the axolotls’ ideal environment.

——美西螈的理想栖息环境。

But when Spanish invaders arrived, they began draining the lakes.

但西班牙入侵者到达后， 他们开始抽干湖水；

And even more water has been diverted in recent years.

近年来，更多的水被引走。

Today, the entire population of wild axolotls is found in just one place,

今天，只发现一个地方 有野生美西螈——索奇米尔科湖，

Lake Xochimilco, where it’s threatened by pollution and invasive fishes.

在那里，它们受到污染 和入侵鱼类的威胁。

People are working to regenerate the ecosystem

人们正努力恢复那里的生态系统，

and strengthen the 2,000 year old chinampa farming tradition.

还强化有 2000 年历史的 奇南帕浮田岛农业传统。

If interest grows, farmers could recover abandoned chinampas

如果收益增加，农民可以恢复 被遗弃的奇南帕浮田岛，

and support the local community— along with the axolotl.

支持美西螈的同时， 也支持了当地社区，

Eventually, the benefits of saving this salamander might be even greater.

最终，拯救美西螈的益处可能更大。

Scientists hope that one day we’ll be able to apply

科学家们希望，

有一天我们

能将美西螈高超的肿瘤抑制 和再生能力应用到人体上。

the axolotl’s masterful tumor suppression and regenerative abilities

to the human body.

Perhaps its secrets are the real reason for the slimy god monster’s smile.

也许，其秘密正是这个黏糊糊 神怪微笑的真正原因。