Process that might have led to first organic molecules

可能导致首个有机分子出现的过程

New research could have relevance to search for extraterrestrial life, green chemistry

新研究可能会涉及寻找地球外生物和绿色化学

New research led by the American Museum of Natural History and funded by NASA identifies a process that might have been key in producing the first organic molecules on Earth about 4 billion years ago, before the origin of life. The process, which is similar to what might have occurred in some ancient underwater hydrothermal vents, may also have relevance to the search for life elsewhere in the universe. Details of the study are published this week in the journal Proceedings of the National Academy of Sciences.

由美国自然历史博物馆牵头并由NASA资助的新研究发现了一项过程。该过程可能在40亿年前，也就是生命起源之前，在地球上产生首个有机分子方面发挥着重要作用。该过程与某些古代深海热泉中发生的反应类似，其可能还与在宇宙中寻找地球外生物有关。研究的详细内容于本周发表于《美国国家科学院院刊》中。

All life on Earth is built of organic molecules -- compounds made of carbon atoms bound to atoms of other elements such as hydrogen, nitrogen and oxygen. In modern life, most of these organic molecules originate from the reduction of carbon dioxide (CO2) through several "carbon-fixation" pathways (such as photosynthesis in plants). But most of these pathways either require energy from the cell in order to work, or were thought to have evolved relatively late. So how did the first organic molecules arise, before the origin of life?

地球上的所有生命都由有机分子构成-有机分子是由与其他诸如氢、氮和氧原子所联接在一起的碳原子构成。在现代生命中，绝大多数此类有机分子来自于二氧化碳的还原，即通过数个“碳素固定”路径（比如植物中的光合作用）。但是绝大多数这类路径要么需要从细胞中获取能量以发挥作用，要么被认为进化相对较晚。那么第一个有机分子是如何在生命起源之前出现的呢？

To tackle this question, Museum Gerstner Scholar Victor Sojo and Reuben Hudson from the College of the Atlantic in Maine devised a novel setup based on microfluidic reactors, tiny self-contained laboratories that allow scientists to study the behavior of fluids -- and in this case, gases as well -- on the microscale. Previous versions of the reactor attempted to mix bubbles of hydrogen gas and CO2 in liquid but no reduction occurred, possibly because the highly volatile hydrogen gas escaped before it had a chance to react. The solution came in discussions between Sojo and Hudson, who shared a lab bench at the RIKEN Center for Sustainable Resource Science in Saitama, Japan. The final reactor was built in Hudson's laboratory in Maine.

为了解决这一问题，博物馆的Gerstner学者Victor Sojo和来自缅因州大西洋学院的Reuben Hudson提出了一个新颖的方法。该方法以微型流体反应器为基础，微型流体反应器是一个微型的设施齐全的实验室。科学家可以在其中从微观的角度研究流体以及气体的特性。之前的反应器试图将氢气泡泡和液状的二氧化碳混合起来，但结果没有发生任何反应，这可能是由于极度易挥发的氢气在有机会发生反应之前就已经挥发了。Sojo和Hudson通过讨论确定了这一解决方案。Sojo和Hudson与日本琦玉的可持续资源科学RIKEN中心共享一个实验台。最终的反应器在Hudson位于缅因的实验室内建造。

"Instead of bubbling the gases within the fluids before the reaction, the main innovation of the new reactor is that the fluids are driven by the gases themselves, so there is very little chance for them to escape," Hudson said.

Hudson表示：“与在反应发生之前在液体内使气体变成泡泡不同，新反应器的主要创新之处在于流体由气体本身产生，因此气体基本没有机会挥发。”

The researchers used their design to combine hydrogen with CO2 to produce an organic molecule called formic acid (HCOOH). This synthetic process resembles the only known CO2-fixation pathway that does not require a supply of energy overall, called the Wood-Ljungdahl acetyl-CoA pathway. In turn, this process resembles reactions that might have taken place in ancient oceanic hydrothermal vents.

研究人员利用他们的设计装置将氢气和二氧化碳相结合并产生一种叫做甲酸（HCOOH）的有机分子。这一过程和唯一已知的CO2-固定路径类似。该路径不需要提供能量并被称为Wood-Ljungdahl acetyl-CoA 路径。反之，该过程和可能出现在古代海洋深海热泉的反应相似。

"The consequences extend far beyond our own biosphere," Sojo said. "Similar hydrothermal systems might exist today elsewhere in the solar system, most noticeably in Enceladus and Europa -- moons of Saturn and Jupiter, respectively -- and so predictably in other water-rocky worlds throughout the universe."

Sojo表示：“这一结果远远超过我们自己的生物圈。同样的热液体系可能在今天存在于太阳系的其他地方，可能性最大的是在土卫二和木卫二中（土星和木星的卫星），因此也可以存在于宇宙中其他由水和岩石组成的世界中。”

"Understanding how carbon dioxide can be reduced under mild geological conditions is important for evaluating the possibility of an origin of life on other worlds, which feeds into understanding how common or rare life may be in the universe," added Laurie Barge from NASA's Jet Propulsion Laboratory, an author on the study.

NASA 喷气推进实验室的Laurie Barge，同样也是该研究的作者补充表示：“理解二氧化碳如何在温和的地质条件下进行还原对于评估其他世界中生命起源的可能性非常重要。其有助于理解普通或稀有的生命如何存在于宇宙中。”

The researchers turned CO2 into organic molecules using relatively mild conditions, which means the findings may also have relevance for environmental chemistry. In the face of the ongoing climate crisis, there is an ongoing search for new methods of CO2reduction.

研究人员利用相对温和的条件将二氧化碳转变为有机分子，这意味着研究结果可能还与环境化学有关联。面对着持续不断的气候危机，寻找新的二氧化碳还原方法将会继续下去。

以上内容摘自《科学日报》并由质控部Susan翻译并编辑