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Usually, they have to work with or against Earth's gravity to move blood around our body,
通常，我们的静脉和动脉都必须与地球引力合作或对抗，才能维持血液在体内的循环流动，
but in microgravity, we see thickening of vascular walls, an increase in vascular stiffness,
但在微重力环境下，我们会看到血管壁变厚，血管硬度增加，
and a ballooning effect in the vasculature of the upper body.
以及上半身血管系统的膨胀效应。
We're actually still not sure if all of this is reversible after an astronaut comes back to earth—that remains to be seen.
实际上，目前我们仍不确定这一切在宇航员返回地球后是否可逆——这还有待观察。
We also confirmed observations made in many other astronauts: spaceflight is associated with altered optical function.
我们还证实了许多在其他宇航员身上也观测到了的结果：太空飞行会伴有视力的变化。
We see swelling of the optical disc, a flattening of the actual globe of the eye, along with other structural changes,
我们看到视神经头会膨胀 ，眼球会扁平化，还有其他结构性变化，
which can lead to onset of blurry vision, blind spots, and more.
这些变化可能会引起视力模糊、出现盲点等。
We haven't been able to pinpoint what causes these changes
我们还不能确定引起这些变化的原因，
but they're obviously not good for your eyesight, and may be permanent.
但它们显然是对我们的视力不好的，还可能造成永久性的损害。
And lastly, blood samples pre-, during, and postflight determined that spaceflight can significantly increase genotoxic stress.
最后，飞行前中后各阶段的血液样本表明，太空飞行会显著增加基因毒性应激。
Space is highly radioactive, and while galactic cosmic rays may sound awesome, they can really do a number on your DNA.
太空是高辐射环境，虽然银河宇宙射线听起来很酷，但它们确实会影响你的DNA。
Cytogenetic analysis, which means looking at changes in your chromosomes, revealed higher levels of genomic instability for the spaceflight twin.
细胞遗传学分析，这意味着观察你染色体的变化，揭示了这对太空飞行双胞胎的基因组不稳定水平比其他宇航员更高。
This comes in the form of increased chromosomal translocations and inversions,
这种变化是以染色体易位和逆位增加的形式出现的，
which can be linked to disorders like infertility and cancer.
可能引起不育和癌症等疾病。
Genetic analysis also revealed dysregulation of genes,
基因分析还揭示了（太空飞行）会引起基因，
especially those associated with immune function and DNA repair,
尤其是那些与免疫功能和DNA修复相关的基因的失调，
and these changes did not return to normal when they got back to Earth.
而这些变化在宇航员回到地球后并没有恢复正常。
All this talk of DNA changing may make it easy to ask the question, "Are they still twins?".
上述这些关于DNA变化的讨论可能会让我们很容易想到这样一个问题：“他们还是双胞胎吗？”
The answer is YES.
答案是肯定的。
Media outlets a while back went a little overboard with the ‘news’ that 7% of Scott Kelly's DNA was different.
前阵子，媒体透露斯科特·凯利的DNA有7%的都和常人不一样了的“新闻”说得有点夸张了。
If 7% of Scott's genes were completely different, not only would he not be Mark's twin anymore, he would be an entirely different species.
如果斯科特有7%的基因都跟普通人完全不一样了，那他不仅不再是马克的双胞胎了，连人类也不是了（黑猩猩和人类的基因差别都不到2%）！
The real way to think about it is that yes, some genetic mutation occurred, but most of the change was epigenetic change.
真正正确的想法是，没错，一些基因突变确实是发生了，但大多数的变化都只是表观遗传变异。
This means that something like DNA methylation, or a little add-on unit to a gene,
这也就意味着DNA甲基化或基因上增加了一个小单元这种变化
changed the way 7% of Scott's DNA was expressed, not the actual makeup of the DNA itself.
只是改变了斯科特7%的基因的表达，并没有改变DNA本身的实际组成。
This can result in upregulation or downregulation of the genes in charge of things like immune function and bone growth.
这类变化可能会导致负责免疫功能和骨骼生长的基因的上调或下调。
So yes. They're still related.
是的，没错。他们两人还是亲戚的。
All of this data represents, as the researchers put it,
正如研究人员所说的那样，所有这些数据都表明，
"a uniquely controlled and integrated framework for comprehensively quantifying astronaut biology in space".
“这是对太空宇航员生物学进行全面量化的一次控制方法独特并有着整体框架的实验”。
And opens up so many exciting questions that are going to be fascinating to build on.
这次实验也提出了许多激动人心又令人着迷的问题。
Even though NASA doesn't currently have any more twins in the pipeline,
尽管NASA目前还没有更多双胞胎可用，
this kind of research can continue with those who take on longer and longer spaceflights.
但这类研究可以由那些飞行时间越来越长的其他宇航员继承下去。
Building a better understanding of the effects of long-term spaceflight on the body and the mind
更好地理解长期太空飞行对人类身体和大脑的影响，
will prepare us to test even more spaceflight boundaries that no human has ever broken before—
能帮助我们准备好探索更多人类从未打破的太空飞行边疆，
while hopefully keeping us all in one piece.
顺利的话还能保我们安然无恙。
We're working on a new series that we're stoked to share with you
接下来我们将推出一个关于生病时我们身体所处状态的新系列，
that's all about what goes on in your body when you get sick.
我们已经迫不及待地想分享给大家了。
And it's called. well. Sick.
这个系列的名字就叫，额，“病了”。
And here's our sneak peak of our first episode.
下面我们先来试看一小段。
When you think about lyme disease, you probably think of this.
说起莱姆病，大家想到的可能是它。
A tick.
一只蜱虫。
Or maybe more specifically a tick bite.
更准确地说是被蜱虫叮咬的部位。
But what exactly is about a tick bite that makes us sick?
但问题是，在被蜱虫叮咬的时候，让我们染病的究竟是什么东西？
Beyond treatments and symptoms,
除了治疗和症状，
we're curious about how exactly viruses, parasites, and other invaders wreak havoc on our health.
我们对病毒、寄生虫和其他入侵者究竟是如何大肆破坏我们的健康这一问题也很感兴趣。
Is there a disease or illness you want us to cover?
您有什么疾病需要我们讨论的吗?
Let us know down in the comments and make sure you subscribe to catch the first episode.
请在下面的评论中告诉我们吧，还有，记得订阅我们的栏目以免错过第一集噢。
Thanks for watching Seeker.
感谢大家的收看。
