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首页> 外文期刊>Biochemistry >Geological Evidence of Oxygenic Photosynthesis and the Biotic Response to the 2400-2200 Ma 'Great Oxidation Event'
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Geological Evidence of Oxygenic Photosynthesis and the Biotic Response to the 2400-2200 Ma 'Great Oxidation Event'

机译：氧合光合作用的地质证据和对2400-2200 Ma'大氧化事件'的生物响应

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摘要

Fossil evidence of photosynthesis, documented in the geological record by microbially laminated stromatolites, microscopic fossils, and carbon isotopic data consistent with the presence of Rubisco-mediated CO2-fixation, extends to ～3500 million years ago. Such evidence, however, does not resolve the time of origin of oxygenic photosynthesis from its anoxygenic photosynthetic evolutionary precursor. Though it is evident that cyanobacteria, the earliest-evolved O2-produc-ing photoautotrophs, existed before ～2450 million years ago — the onset of the "Great Oxidation Event" (GOE) that forever altered Earth's environment — O2-producing photosynthesis seems certain to have originated hundreds of millions of years earlier. How did Earth's biota respond to the GOE? Four lines of evidence are here suggested to reflect this major environmental transition: (1) rRNA phylogeny-correlated metabolic and biosynthetic pathways document evolution from an anaerobic (pre-GOE) to a dominantly oxygen-requiring (post-GOE) biosphere; (2) consistent with the rRNA phylogeny of cyanobacteria, their fossil record evidences the immediately post-GOE presence of cyanobacterial nostocaceans characterized by specialized cells that protect their oxygen-labile nitrogenase enzyme system; (3) the earliest known fossil eukaryotes, obligately aerobic phytoplankton and putative algae, closely post-date the GOE; and (4) microbial sulfuretums are earliest known from rocks deposited during and immediately after the GOE, their apparent proliferation evidently spurred by an increase of environmental oxygen and a resulting upsurge of metabolically useable sulfate and nitrate. Though the biotic response to the GOE is a question new to paleobiology that is yet largely unexplored, additional evidence of its impact seems certain to be uncovered.
机译：微生物记录的叠层石，微观化石和与Rubisco介导的CO2固定存在一致的碳同位素数据在地质记录中记录了光合作用的化石证据，这一发现已扩展到约35亿年前。然而，这些证据不能解决其光生氧进化先驱体产生光合光子的时间。尽管有证据表明，最早发展为O2的光合自养生物蓝细菌存在于约2.45亿年前，这是永久改变地球环境的“大氧化事件”（GOE）的发生-产生O2的光合作用似乎是肯定的起源于数亿年前。地球生物群系对GOE有何反应？本文提出了四项证据来反映这一主要的环境转变：（1）rRNA系统发育相关的代谢和生物合成途径记录了从厌氧（GOE前）到主要需要氧气（GOE后）生物圈的演化; （2）与蓝细菌的rRNA系统发育一致，它们的化石记录表明，GOE后立即存在以特殊细菌保护其对氧不稳定的氮酶系统为特征的蓝细菌菌丝藻。 （3）最早的已知化石真核生物，即专性有氧浮游植物和推定藻类，紧接在GOE之后; （4）最早在GOE期间和之后沉积的岩石中发现了微生物的硫，它们的表观增殖显然是由于环境氧的增加和可代谢利用的硫酸盐和硝酸盐的增加而引起的。尽管对GOE的生物反应是古生物学的一个新问题，但尚未得到充分探索，但似乎有待进一步发现其影响的证据。

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