原始的Asgard生命形式已经在实验室中成功生长
原始的Asgard生命形式已经在实验室中成功生长
When scientists ran DNA analysis on a sediment core taken from the floor of the Arctic ocean back in 2010, they found something surprising. A previously unknown organism belonging to the strange domain of microbes called Archaea appeared to have genomic characteristics associated with a totally different domain - Eukaryota.
当科学家们在2010年对取自北冰洋海底的沉积物核心进行DNA分析时，他们发现了一些令人惊讶的事情。一种以前不为人知的生物，属于一种叫做古菌的奇怪的微生物领域，它似乎具有与一个完全不同的领域——真核生物相关的基因组特征。
They named their discovery Lokiarchaeota, after the Loki's Castle hydrothermal vent near Greenland where it was found; but doubt shadowed the finding. Could the sample have been contaminated by something else in the core?
他们将这一发现命名为Lokiarchaeota，以发现它的格陵兰岛附近Loki城堡的热液喷口命名;但这一发现受到了质疑。样本会不会被其他东西污染了呢?
Now, thanks to the work of Japanese scientists, those doubts can be put to rest. For the first time, they have isolated Lokiarchaeota, and grown it in a lab.
现在，多亏了日本科学家的工作，这些疑虑得以消除。他们第一次分离出了Lokiarchaeota，并在实验室里培育它。
That means, for the first time, researchers can closely study and interact with living Lokiarchaeota, which could help us to find our very first ancestors on this incredible blue planet. Their research was released last year and has now been published in the journal Nature.
这意味着，研究人员第一次可以近距离研究并与现存的Lokiarchaeota相互作用，这将帮助我们在这个不可思议的蓝色星球上找到我们的最早的祖先。他们的研究发表于去年，现已发表在《自然》杂志上。
The tree of life, at its base, is divided into three domains. One of those is occupied by bacteria - single-celled microbes that don't have a nucleus or membrane-bound organelles, and get around by waving hair-like structures called flagella. Another is eukaryotes, organisms whose cells have nuclei and membranes. That domain includes us humans, animals, plants, and algae.
生命之树，在它的基础上，被分为三个领域。其中一种是细菌——单细胞微生物，没有细胞核或膜结合的细胞器，通过被称为鞭毛的毛发状结构四处移动。另一种是真核生物，即细胞有细胞核和细胞膜的生物。这个领域包括我们人类、动物、植物和藻类。
And then there are archaea. These are a lot like bacteria, in that they lack nuclei and membrane-bound organelles, and get around using flagella. But there are a few key differences. They divide differently. Their cell walls are made of slightly different stuff. And their RNA is different enough to separate them on the phylogenetic tree.
还有古菌。它们很像细菌，因为它们没有细胞核和膜结合的细胞器，只能靠鞭毛活动。但有几个关键的区别。他们将不同。它们的细胞壁是由稍微不同的物质构成的。它们的RNA差异很大，足以在系统发育树上把它们分开。
But then along came Lokiarchaeota - followed by other archaea specimens that had eukaryotic characteristics. These were named Thorarchaeota, Odinarchaeota and Heimdallarchaeota (to follow the same naming convention).
但随后出现了Lokiarchaeota——随后出现了其他具有真核生物特征的古细菌标本。它们被命名为Thorarchaeota、Odinarchaeota和Heimdallarchaeota(遵循相同的命名惯例)。
Collectively, they are called the Asgard archaea, and some scientists think they could be the origin of eukaryotic life - perhaps after an Asgard-like archaeon swallowed up a bacterium.
它们被统称为阿斯加德古菌，一些科学家认为它们可能是真核生物的起源——也许是在一种类似阿斯加德的古生菌吞噬了一种细菌之后。
But it's hard to tell without studying the organisms in isolated detail. This is where the Japanese scientists come in. They retrieved a sediment core from the seabed in the Nankai Trough, 2,533 metres (8,310 feet) below sea level, in 2006.
但是，如果不单独研究这些生物的细节，就很难判断。这就是日本科学家的用武之地。2006年，他们在海平面以下2533米(8310英尺)的南开海沟从海床上取回了一个沉积物核心。
This was before anyone knew about Asgard archaea. Only later, an RNA analysis of their rich sample revealed the presence of a Lokiarchaeota-like organism.
这是在有人知道阿斯加德古菌之前。后来，对他们丰富的样本进行RNA分析，发现了一种类似于lokiarchaeota的生物。
When the team started their work, they didn't know this yet. They carefully cultivated their samples for five years, in a methane-fed continuous-flow bioreactor system designed to mimic the conditions of a deep-sea methane vent. Very slowly, the microbes multiplied.
当团队开始他们的工作时，他们还不知道这一点。他们在一个甲烷连续流生物反应器系统中精心培养他们的样本五年，该系统旨在模拟深海甲烷喷口的条件。微生物繁殖非常缓慢。
The next step was to place samples from the bioreactor in glass tubes with nutrients to keep them fed and growing. There they sat for another year, finally starting to develop a very faint population of Lokiarchaeota.
下一步是将来自生物反应器的样品放入装有营养物质的玻璃管中，以保持其营养和生长。在那里他们又用了一年，最后开始形成一个非常微弱的Lokiarchaeota种群。
