原始的Asgard生命形式已經(jīng)在實(shí)驗(yàn)室中成功生長

原始的Asgard生命形式已經(jīng)在實(shí)驗(yàn)室中成功生長

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.

當(dāng)科學(xué)家們在2010年對(duì)取自北冰洋海底的沉積物核心進(jìn)行DNA分析時(shí)，他們發(fā)現(xiàn)了一些令人驚訝的事情。一種以前不為人知的生物，屬于一種叫做古菌的奇怪的微生物領(lǐng)域，它似乎具有與一個(gè)完全不同的領(lǐng)域——真核生物相關(guān)的基因組特征。

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?

他們將這一發(fā)現(xiàn)命名為Lokiarchaeota，以發(fā)現(xiàn)它的格陵蘭島附近Loki城堡的熱液噴口命名;但這一發(fā)現(xiàn)受到了質(zhì)疑。樣本會(huì)不會(huì)被其他東西污染了呢?

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.

現(xiàn)在，多虧了日本科學(xué)家的工作，這些疑慮得以消除。他們第一次分離出了Lokiarchaeota，并在實(shí)驗(yàn)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.

這意味著，研究人員第一次可以近距離研究并與現(xiàn)存的Lokiarchaeota相互作用，這將幫助我們在這個(gè)不可思議的藍(lán)色星球上找到我們的最早的祖先。他們的研究發(fā)表于去年，現(xiàn)已發(fā)表在《自然》雜志上。

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.

生命之樹，在它的基礎(chǔ)上，被分為三個(gè)領(lǐng)域。其中一種是細(xì)菌——單細(xì)胞微生物，沒有細(xì)胞核或膜結(jié)合的細(xì)胞器，通過被稱為鞭毛的毛發(fā)狀結(jié)構(gòu)四處移動(dòng)。另一種是真核生物，即細(xì)胞有細(xì)胞核和細(xì)胞膜的生物。這個(gè)領(lǐng)域包括我們?nèi)祟?、?dòng)物、植物和藻類。

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.

還有古菌。它們很像細(xì)菌，因?yàn)樗鼈儧]有細(xì)胞核和膜結(jié)合的細(xì)胞器，只能靠鞭毛活動(dòng)。但有幾個(gè)關(guān)鍵的區(qū)別。他們將不同。它們的細(xì)胞壁是由稍微不同的物質(zhì)構(gòu)成的。它們的RNA差異很大，足以在系統(tǒng)發(fā)育樹上把它們分開。

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).

但隨后出現(xiàn)了Lokiarchaeota——隨后出現(xiàn)了其他具有真核生物特征的古細(xì)菌標(biāo)本。它們被命名為Thorarchaeota、Odinarchaeota和Heimdallarchaeota(遵循相同的命名慣例)。

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.

它們被統(tǒng)稱為阿斯加德古菌，一些科學(xué)家認(rèn)為它們可能是真核生物的起源——也許是在一種類似阿斯加德的古生菌吞噬了一種細(xì)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，如果不單獨(dú)研究這些生物的細(xì)節(jié)，就很難判斷。這就是日本科學(xué)家的用武之地。2006年，他們在海平面以下2533米(8310英尺)的南開海溝從海床上取回了一個(gè)沉積物核心。

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.

這是在有人知道阿斯加德古菌之前。后來，對(duì)他們豐富的樣本進(jìn)行RNA分析，發(fā)現(xiàn)了一種類似于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.

當(dāng)團(tuán)隊(duì)開始他們的工作時(shí)，他們還不知道這一點(diǎn)。他們在一個(gè)甲烷連續(xù)流生物反應(yīng)器系統(tǒng)中精心培養(yǎng)他們的樣本五年，該系統(tǒng)旨在模擬深海甲烷噴口的條件。微生物繁殖非常緩慢。

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.

下一步是將來自生物反應(yīng)器的樣品放入裝有營養(yǎng)物質(zhì)的玻璃管中，以保持其營養(yǎng)和生長。在那里他們又用了一年，最后開始形成一個(gè)非常微弱的Lokiarchaeota種群。