评论
打印
When it comes to mythical one-eyed creatures, the first thing you think of is probably the Cyclops.
说起神话中的独眼生物，你首先想到的可能是库克罗普斯（独眼巨人）。
There are also lots of other legendary creatures to choose from, too,
还有很多其他传说中的生物，
from the Irish god Balor, who only opens his eye to bring destruction,
比如从爱尔兰神巴洛炎魔，他一开眼就会到来破坏，
to the mostly harmless Hitotsume-kozō of Japan.
到最人畜无害的日本一目小僧。
In nature, on the other hand, eyes pretty much always come in twos,
事实上另一方面，眼睛总是成对生长的，
and there’s no vertebrate species that evolved to have one eye.
还没有哪种脊椎动物进化成了独眼生物。
That said, if something goes wrong during its development as an embryo,
即便如此，如果在胚胎成长阶段出现失误，
any vertebrate can develop what's known as cyclopia, a condition named after those one-eyed creatures of legend.
任何脊椎动物都可能变成独眼畸形——一种以传说中的独眼生物命名的病情。
It's a devastating complication, and generally fatal.
这是一种具有破坏性的并发症，通常是致命的。
But studying it might help researchers discover new ways to treat certain types of cancers.
但对其进行研究可能有助于研究员们发现治疗某种癌症的新方法。
Most of the reports you'll find about real cyclopic animals were spread through the internet,
你会发现大多数关于真实独眼动物的报道都在网上传播，
but news of cyclops lambs, goats, sharks, and humans is nothing new.
但是独眼巨人、小羊、山羊、鲨鱼和人类的新闻却并不新鲜。
There's even a fairly accurate description of a pig born with cyclopia that dates back to a Connecticut colony in 1642.
追溯到1642年康涅狄格殖民地时期，甚至还有关于一只天生独眼猪的非常准确的描述。
So how does an animal that normally has two eyes develop only one in the center of its face?
所以正常情况下的两眼动物是如何长成只有脸中间一支眼的呢？
The New Haven colonists claimed that their stillborn piglet was the product of bestiality, but they were wrong very wrong.
纽黑文殖民居民称他们那里的死胎小猪是人兽杂交的产物，但是他们错的很离谱。
It all has to do with how the brain develops.
所有这些都和大脑如何发育有关。
In a developing vertebrate embryo, the brain consists of three regions: the hindbrain, the midbrain, and the forebrain.
在一个发育中的脊椎动物胚胎中，大脑由三个区域组成：后脑、中脑以及前脑。
The forebrain eventually differentiates into two parts:
前脑最终会分化成两个部分：
the diencephalon, which becomes inner parts of the brain like the thalamus and the hypothalamus,
间脑，它会变成大脑的内部区比如丘脑和下丘脑，
and the telencephalon, which turns into the cerebrum.
以及端脑，它会变成大脑。
In humans, this happens around week 4 or 5 of gestation.
这种变化在人类妊娠期的约四或五周发生。
But sometimes, the forebrain doesn't completely split,
但有时前脑没有完全分裂开，
which hinders the development of a lot of important brain structures, including the left and right hemispheres.
这就阻碍了许多重要大脑结构的发育，包括左右脑。
The condition is called holoprosencephaly, or HPE,
这种情况被称为前脑无裂畸形或HPE，
and it can vary in severity depending on how much of the brain's development is affected.
其严重性取决于大脑发育所受影响的程度。
Cyclopia is basically the rarest and most severe form of HPE,
独眼畸形基本上是HPE最罕见最严重的形式，
and it's named after its most noticeable side effect: a single ocular tract in the center of the face.
并以其最明显的副作用而命名：位于面部中间的单眼径。
Embryos also usually develop a proboscis positioned above the eye,
胚胎通常还会发育成鼻子长在了眼睛上边的情况，
and they tend to have other severe physical defects that differ from case to case.
并且不同情况中还会有其他严重的生理缺陷。
In humans, cyclopia is rare: it's found in an estimated 1 in 100,000 births, although unfortunately, it's always fatal.
独眼畸形在人类中比较罕见：估计十万个新生儿中有一个独眼畸形，不幸的是这种畸形总是致命的。
But the less severe forms of HPE are more common.
其他没那么严重的HPE形式更为常见。
Overall, HPE happens in about 1 in 250 conceptions and 1 in 16,000 live births, and it can be survivable.
总的来说，250个受孕中约有一个会发生HPE，并且一万六千个活产儿中就有一例，但并不致死。
Part of the reason HPE is so common is that it can be caused by a lot of different factors,
HPE非常普遍的部分原因是因为有多种不同因素都会引发HPE，
from a single genetic mutation, to an extracopy of a chromosome,
从单基因突变到染色体的额外复制，
to teratogens, which are substances that cause birth defects when a developing embryo is exposed to them.
再到致畸剂，当发育胚胎暴露在致畸剂下时，致畸剂中的物质就会导致先天畸形。
For researchers, learning more about those causes is important because it can help prevent birth defects,
对研究员而言，对这些诱因进行深入了解是非常重要的，因为这可以帮助预防先天畸形，
but also because they have a lot in common with processes that lead to certain kinds of cancer.
还因为这些诱因与导致某类癌症的过程有很多相似之处。
The main gene connected with HPE is called Sonic hedgehog, or SHH for short.
与HPE相连的主要基因被称为音猬因子，或简称SHH。
It doesn't actually have anything to do with running really fast, but scientists named it that
事实上这和跑得快没有任何关系，科学家这样命名
because there's a related genetic mutation in fruit flies that makes them look like they're covered in spines.
是因为果蝇中有一个相关的基因突变使它们看上去像浑身覆盖着刺一样。
And because scientists are nerds.
还因为科学家们是书呆子。
The protein SHH codes for, which is also called Shh, plays a crucial role in embryonic development,
蛋白质SHH对Shh的指定遗传密码在胚胎发育中起到了关键作用，
including telling the forebrain how to differentiate and form hemispheres.
包括告诉前脑如何分化并组成半脑。
But the Shh protein doesn't work alone — it's sort of a delegating boss,
但是Shh蛋白质并不是单独工作的——它就有点像是授权的老板，
telling another protein to instruct a third protein to bind to a cell's DNA to activate a gene,
命令另一蛋白质去指导第三个蛋白质与细胞的DNA捆绑以激活一个基因，
in what's known as the Shh signaling pathway.
这被称为Shh信号通路。
Since there are so many steps involved, there are a lot of ways things can go wrong.
由于其中参与的步骤太多，出错的地方也多。
If the embryo is exposed to any compound that interrupts this flow of instructions,
如果胚胎暴露于任何中断指令流的化合物之下，
Shh can't tell cells in the forebrain to differentiate.
Shh就无法告诉前脑细胞如何分化。
And if the cells don't know to differentiate, that leads to HPE.
如果细胞不知道如何分化，就会导致HPE。
Even though SHH is a really important gene in embryos, it's mostly dormant after birth.
虽然SHH是胚胎中非常重要的基因，但在生产后，它基本会进入休眠。
But if it gets activated somehow,
但如果它被莫名激活，
it can cause uncontrolled cell division that leads to all kinds of cancers — from lung to pancreatic to skin cancer.
就会引发不受控制的细胞分裂从而导致各种癌症——从肺癌到胰腺癌再到皮肤癌。
In an embryo, interfering with the Shh pathway can be devastating — it's what leads to HPE.
在一个胚胎中，妨碍Shh通道是极具破坏性的——这会导致HPE。
But to treat a cancer that's caused by the pathway activating when it isn't supposed to,
但是要治疗这种因在不当情况下激活通道而导致的癌症，
interfering with it is exactly what you want to do.
妨碍Shh通道恰恰你想要做的。
And in 1968, researchers discovered a compound that obstructs the Shh pathway,
1968年，研究员们发现了一种阻碍Shh通道的化合物，
thanks to a population of Idaho sheep that kept giving birth to cyclopic lambs.
这多亏了爱达荷州的羊不断产出独眼羔羊。
After more than a decade of research, scientists were able to isolate the responsible compound from the California corn lily.
经过十多年的研究后，科学家们可以将负责阻碍的化合物从加利福尼亚的黄七筋菇中隔离出来。
They named it cyclopamine.
他们将其命名为环巴胺。
Pregnant ewes ate the plants while grazing, which caused their offspring to develop all kinds of birth defects.
放牧时给怀孕的母羊喂食这种植物，导致了她们生下的小羊各种先天畸形。
Lab tests showed that if they ate the cyclopamine on the 14th day of gestation, the lambs developed cyclopia.
实验室测试发现如果它们在妊娠期的第十四天吃环巴胺，生下的小羊就会是独眼畸形。
So now, researchers are trying to take advantage of how cyclopamine disrupts the Shh pathway to save lives.
所以现在研究员们正尝试利用环巴胺阻碍Shh通道这一点来拯救生命。
It's taking a while because cyclopamine is a complicated molecule,
拯救生命还要再等等，因为环巴胺是一种复杂的分子，
and they've had a tough time figuring out how to either make or extract enough of it to study it properly.
科学家们一直艰难地致力于制造或提取足量的环巴胺进行适当研究。
It's been even harder to make a version that's absorbed and used by the body in a way that would make it an effective cancer treatment.
更难的是要制造出一种样本，可以被人体吸收利用，这样才能有效地治疗癌症。
But they're working on it, and versions of cyclopamine
但科学家们还在不断地努力，环巴胺样本
and other compounds that disrupt that pathway are being tested against things like pancreatic and skin cancer.
以及其他可以阻碍通道的化合物被用于进行胰腺癌和皮肤癌治疗测试。
So, someday, the story of some lambs and a rare birth defect might save thousands of lives every year.
所有也许有一天，羔羊和罕见先天畸形的故事能够拯救上千条性命。
Thanks for watching this episode of SciShow.
感谢收看本期科学秀。
If you're interested in learning more about how cancer works,
如果你想了解更多关于癌症的知识，
you can watch our video about why we haven't cured it yet
你可以观看我们的视频，了解虽然我们投入大量的时间和金钱
even though there's so much time and money being poured into cancer research.
可为什么还是无法治愈癌症。
