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Microaerobic steroid biosynthesis and the molecular fossil record of Archean life

Waldbauer, Jacob R. and Newman, Dianne K. and Summons, Roger E. (2011) Microaerobic steroid biosynthesis and the molecular fossil record of Archean life. Proceedings of the National Academy of Sciences of the United States of America, 108 (33). pp. 13409-13414. ISSN 0027-8424. PMCID PMC3158215.

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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 O_2 in the environment, molecular fossils offer a unique record of O_2 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 O_2 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 O_2 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 O_2. In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today.

Item Type:Article
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URLURL TypeDescription DOIArticle CentralArticle
Newman, Dianne K.0000-0003-1647-1918
Summons, Roger E.0000-0002-7144-8537
Additional Information:© 2011 National Academy of Sciences. Edited by John M. Hayes, Woods Hole Oceanographic Institution, Berkeley, CA, and approved July 5, 2011 (received for review March 19, 2011). Published online before print August 8, 2011. We are grateful to Alexa Price-Whelan and Paula Welander for guidance with anaerobic culturing techniques, to Lars Dietrich for assistance with microelectrode measurements, and to Maureen Coleman for comments, discussion, and help with model visualization. We also acknowledge helpful comments by Lee Kump and two anonymous reviewers that improved the manuscript. This work was supported by grants from the National Aeronautics and Space Administration Astrobiology Institute and the Agouron Institute (to R.E.S. and D.K.N.), by the Howard Hughes Medical Institute (HHMI), and by an Office of Naval Research National Defense Science and Engineering Graduate Fellowship and an National Science Foundation Graduate Research Fellowship (to J.R.W.). D.K.N. is an HHMI Investigator. Author contributions: J.R.W., D.K.N., and R.E.S. designed research; J.R.W. performed research; J.R.W. and R.E.S. analyzed data; and J.R.W., D.K.N., and R.E.S. wrote the paper.
Funding AgencyGrant Number
Agouron InstituteUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Office of Naval Research (ONR)UNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
Subject Keywords:biomarker; photosynthesis; sterols; hypoxia; ocean
Issue or Number:33
PubMed Central ID:PMC3158215
Record Number:CaltechAUTHORS:20130403-162415003
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37752
Deposited By: Jason Perez
Deposited On:04 Apr 2013 15:06
Last Modified:02 Jun 2020 20:43

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