第一个不需要呼吸的动物在鲑鱼体内被发现

第一个不需要呼吸的动物在鲑鱼体内被发现

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.

来自特拉维夫的一组科学家发现了一种不需要呼吸就能生存的动物，这在世界上还是第一次。发表在《美国国家科学院院刊》上的这篇论文描述了一种类似水母的寄生虫，它是已知的第一个没有线粒体基因组的多细胞生物，这意味着它完全能够在没有氧气的情况下生存。

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?

科学的进步不断挑战着人们长期以来对我们的星球和宇宙的假设，但谁能想到一个颠覆我们对动物王国认识的突破性发现会在鲑鱼体内找到呢?

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是一种微小的寄生虫，仅由10个细胞组成，栖息在鲑鱼肌肉中。作为黏液动物纲的一员，黏液动物是一种专性寄生的海洋动物，尽管它看起来像蝌蚪，但实际上它与水母和珊瑚有亲缘关系——它们都进行有氧呼吸。然而，这种生活在鲑鱼体内的寄生虫已经放弃了获取能量的这一关键途径，成为已知的第一个可以在没有氧气的情况下生存的多细胞生物。

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.

令人惊讶的是，当特拉维夫大学的研究小组开始组装亨内古雅基因组时，他们并没有寻找到重大的科学突破。这一发现是在一次偶然的观察中发现的，因为它不包括线粒体基因组，而线粒体编码线粒体，在线粒体中，氧气被捕获来制造能量。没有这种细胞特征，寄生虫就不能将氧气作为呼吸的一种方式。

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.

高度发达的多细胞生物首次出现在地球上的时候，正是氧气水平飙升的时候，这为所有动物必须进行有氧呼吸的假设奠定了基础。尽管对于生活在厌氧环境中的动物是否符合这种模式一直存在争议，但这是首次发现的证据，证明动物可以在没有氧气的情况下生存。

"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."

“一般认为，在进化过程中，生物变得越来越复杂，简单的单细胞或少细胞生物是复杂生物的祖先。”TAU大学生命科学学院和斯坦哈特自然历史博物馆动物学院的首席研究员Huchon教授在一份声明中说。“但是，就在我们面前，有一种动物的进化过程正好相反。它生活在一个无氧的环境中，去掉了不必要的负责有氧呼吸的基因，变成了一种更简单的有机体。”

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.

这一突破不仅对我们关于地球上有生命的假设提出了重要问题，而且对其他行星上有生命的可能性也提出了重要问题。曾经因为缺氧而被排除在外的地外环境很有可能是多细胞生物的栖息地，这些多细胞生物能够像Henneguya一样在厌氧条件下生存。

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...

这项研究表明，即使是在地球上看起来不适合居住的角落，动物王国也会贪婪地努力居住。即使鲑鱼体内的厌氧条件很差…