Microaerobic steroid biosynthesis and the molecular fossil record of Archean life
Microaerobic steroid biosynthesis and the molecular fossil record of Archean life
复制标题
微需氧类固醇生物合成与太古宙生命的分子化石记录
DOI：
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发表时间：
2011
影响因子：
11.1
通讯作者：
R. Summons
中科院分区：
文献类型：
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作者：
J. Waldbauer;D. Newman;R. Summons
从细胞呼吸到岩石风化，分子氧驱动着许多关键的生物地球化学过程，这使得重建其生产和积累的历史成为理解地球演化的首要问题。在环境中氧气存在的各种地球化学指标中，分子化石提供了氧气最初由生物产生和消费的独特记录：在阳光充足的水生栖息地。由于类固醇的生物合成需要分子氧，化石中的甾烷被用来推断早前寒武纪的需氧作用。然而，对这种生物化学的氧气需求进行更好的定量限制，将澄清这些分子化石在生产时对环境条件的影响。在这里，我们证明类固醇的生物合成是一个微氧过程，在纳摩尔范围内的溶解氧浓度使之成为可能。我们提出的证据表明，在大气O2的最早地质和同位素证据之前，微氧海洋环境(可能存在类固醇生物合成)可能已经广泛存在并持续了很长一段时间。在太古宙晚期，分子氧很可能作为生物成因的微量气体循环，很像今天的二甲基硫化物等化合物。
The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth’s evolution. Among the various geochemical proxies for the presence of O2 in the environment, molecular fossils offer a unique record of O2 where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O2 requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O2 concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O2. In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today.
影响因子：
18.3
作者：
Kendall, Brian;Reinhard, Christopher T.;Anbar, Ariel D.
通讯作者：
Anbar, Ariel D.