第一個不需要呼吸的動物在鮭魚體內(nèi)被發(fā)現(xiàn)

第一個不需要呼吸的動物在鮭魚體內(nèi)被發(fā)現(xiàn)

In a world-first a team of scientists from Tel Aviv has discovered an animal that doesn’t need to breathe to survive, putting that tired, old anagram Mrs Nerg firmly back in her box. The paper published in PNAS describes a jellyfish-like parasite, which is the first known multicellular organism lacking a mitochondrial genome, meaning it’s perfectly capable of surviving without oxygen.

來自特拉維夫的一組科學家發(fā)現(xiàn)了一種不需要呼吸就能生存的動物，這在世界上還是第一次。發(fā)表在《美國國家科學院院刊》上的這篇論文描述了一種類似水母的寄生蟲，它是已知的第一個沒有線粒體基因組的多細胞生物，這意味著它完全能夠在沒有氧氣的情況下生存。

Advances in science are constantly challenging long-held assumptions about our planet and the universe, but who would’ve thought a groundbreaking discovery that completely flips our understanding of the animal kingdom would be found inside a salmon?

科學的進步不斷挑戰(zhàn)著人們長期以來對我們的星球和宇宙的假設(shè)，但誰能想到一個顛覆我們對動物王國認識的突破性發(fā)現(xiàn)會在鮭魚體內(nèi)找到呢?

Henneguya salminicola is a tiny parasite that consists of just ten cells and inhabits salmon muscle. As a member of the class Myxozoa, a group of obligately parasitic marine animals, though it looks like a tadpole it’s actually related to jellyfish and corals – both of which practice aerobic respiration. This salmon-dwelling parasite, however, has given up this critical pathway for sourcing energy, becoming the first-known multicellular organism that can exist without oxygen.

Henneguya salminicola是一種微小的寄生蟲，僅由10個細胞組成，棲息在鮭魚肌肉中。作為黏液動物綱的一員，黏液動物是一種專性寄生的海洋動物，盡管它看起來像蝌蚪，但實際上它與水母和珊瑚有親緣關(guān)系——它們都進行有氧呼吸。然而，這種生活在鮭魚體內(nèi)的寄生蟲已經(jīng)放棄了獲取能量的這一關(guān)鍵途徑，成為已知的第一個可以在沒有氧氣的情況下生存的多細胞生物。

Light microscope image of spores of the parasitic cnidarian Henneguya salminicola, from Chinook salmon. Stephen Douglas Atkinson

Amazingly, the team at Tel Aviv University wasn’t looking for an enormous scientific breakthrough when they began assembling the Henneguya genome. The discovery came about by accident when it was observed it didn’t include a mitochondrial genome, which codes for the mitochondria where oxygen is captured to make energy. Without this cell feature, which is imperative for all other animal life, the parasite couldn’t be processing oxygen as a means of respiration.

令人驚訝的是，當特拉維夫大學的研究小組開始組裝亨內(nèi)古雅基因組時，他們并沒有尋找到重大的科學突破。這一發(fā)現(xiàn)是在一次偶然的觀察中發(fā)現(xiàn)的，因為它不包括線粒體基因組，而線粒體編碼線粒體，在線粒體中，氧氣被捕獲來制造能量。沒有這種細胞特征，寄生蟲就不能將氧氣作為呼吸的一種方式。

Highly developed, multicellular organisms first appeared on Earth at a time when oxygen levels spiked, which formed the basis of the assumption that all animals must respire aerobically. While there has been some debate as to whether animals living in anaerobic environments fit this mold, this is the first time evidence has been uncovered that proves animals can exist without oxygen.

高度發(fā)達的多細胞生物首次出現(xiàn)在地球上的時候，正是氧氣水平飆升的時候，這為所有動物必須進行有氧呼吸的假設(shè)奠定了基礎(chǔ)。盡管對于生活在厭氧環(huán)境中的動物是否符合這種模式一直存在爭議，但這是首次發(fā)現(xiàn)的證據(jù)，證明動物可以在沒有氧氣的情況下生存。

"It is generally thought that during evolution, organisms become more and more complex, and that simple single-celled or few-celled organisms are the ancestors of complex organisms," said lead researcher Professor Huchon, of the School of Zoology at TAU's Faculty of Life Sciences and Steinhardt Museum of Natural History, in a statement. "But here, right before us, is an animal whose evolutionary process is the opposite. Living in an oxygen-free environment, it has shed unnecessary genes responsible for aerobic respiration and become an even simpler organism."

“一般認為，在進化過程中，生物變得越來越復雜，簡單的單細胞或少細胞生物是復雜生物的祖先。”TAU大學生命科學學院和斯坦哈特自然歷史博物館動物學院的首席研究員Huchon教授在一份聲明中說。“但是，就在我們面前，有一種動物的進化過程正好相反。它生活在一個無氧的環(huán)境中，去掉了不必要的負責有氧呼吸的基因，變成了一種更簡單的有機體。”

The breakthrough poses important questions about not only our assumptions of life on Earth but also the possibility of life on other planets. It’s possible that extraterrestrial environments that were once ruled out due to a lack of oxygen could potentially be harboring multicellular organisms that are capable of surviving in anaerobic conditions just like Henneguya.

這一突破不僅對我們關(guān)于地球上有生命的假設(shè)提出了重要問題，而且對其他行星上有生命的可能性也提出了重要問題。曾經(jīng)因為缺氧而被排除在外的地外環(huán)境很有可能是多細胞生物的棲息地，這些多細胞生物能夠像Henneguya一樣在厭氧條件下生存。

The research demonstrates the voracious efforts of the animal kingdom to inhabit even the seemingly uninhabitable corners of the Earth. Even when the inside of a salmon poses unfavorably anaerobic conditions...

這項研究表明，即使是在地球上看起來不適合居住的角落，動物王國也會貪婪地努力居住。即使鮭魚體內(nèi)的厭氧條件很差…