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| Van Maldegem, Lennart M.; Sansjofre, Pierre; Weijers, Johan W. H.; Wolkenstein, Klaus; Strother, Paul K.; Woermer, Lars; Hefter, Jens; Nettersheim, Benjamin J.; Hoshino, Yosuke; Schouten, Stefan; Damste, Jaap S. Sinninghe; Nath, Nilamoni; Griesinger, Christian; Kuznetsov, Nikolay B.; Elie, Marcel; Elvert, Marcus; Tegelaar, Erik; Gleixner, Gerd; Hallmann, Christian. |
| Eukaryotic algae rose to ecological relevance after the Neoproterozoic Snowball Earth glaciations, but the causes for this consequential evolutionary transition remain enigmatic. Cap carbonates were globally deposited directly after these glaciations, but they are usually organic barren or thermally overprinted. Here we show that uniquely-preserved cap dolostones of the Araras Group contain exceptional abundances of a newly identified biomarker: 25,28-bisnorgammacerane. Its secular occurrence, carbon isotope systematics and co-occurrence with other demethylated terpenoids suggest a mechanistic connection to extensive microbial degradation of ciliate-derived biomass in bacterially dominated ecosystems. Declining 25,28-bisnorgammacerane concentrations, and a... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74951/76030.pdf |
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| Hoshino, Yosuke; Poshibaeva, Aleksandra; Meredith, William; Snape, Colin; Poshibaev, Vladimir; Versteegh, Gerard J. M.; Kuznetsov, Nikolay; Leider, Arne; Van Maldegem, Lennart; Neumann, Mareike; Naeher, Sebastian; Moczydlowska, Malgorzata; Brocks, Jochen J.; Jarrett, Amber J. M.; Tang, Qing; Xiao, Shuhai; Mckirdy, David; Das, Supriyo Kumar; Alvaro, Jose Javier; Sansjofre, Pierre; Hallmann, Christian. |
| Sedimentary hydrocarbon remnants of eukaryotic C-26-C-30 sterols can be used to reconstruct early algal evolution. Enhanced C-29 sterol abundances provide algal cellmembranes a density advantage in large temperature fluctuations. Here, we combined a literature review with new analyses to generate a comprehensive inventory of unambiguously syngenetic steranes in Neoproterozoic rocks. Our results show that the capacity for C-29 24ethyl- sterol biosynthesis emerged in the Cryogenian, that is, between 720 and 635 million years ago during the Neoproterozoic Snowball Earth glaciations, which were an evolutionary stimulant, not a bottleneck. This biochemical innovation heralded the rise of green algae to global dominance of marine ecosystems and highlights the... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75021/75667.pdf |
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