Distribution and source of 1-O-monoalkyl glycerol ethers in the Yellow River and Bohai Sea

Wang, Y.; Xu, Yunping

doi:10.1016/j.orggeochem.2015.10.012

Cited by 9 publications

(8 citation statements)

References 53 publications

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“…The analysis of the polar lipid fraction in our samples sheds further light on paleoenvironmental conditions. Samples collected from the LAS layer show a very unusual distribution of functionalized lipids, including monoalkyl glycerol monoethers (MAGEs), which have been often interpreted as biomarkers for sulfate-reducing bacteria (SRB) and/or thermophilic organisms (27,28,37), among other possible biological sources (38,39). These glycerol ether lipids are sometimes present in high concentrations at marine hydrothermal vents and cold seeps and in terrestrial geothermal sediments (27)(28)(29)(30).…”

Section: Resultsmentioning

confidence: 99%

Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma

Sistiaga

Husain

Uribelarrea

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Landscape-scale reconstructions of ancient environments within the cradle of humanity may reveal insights into the relationship between early hominins and the changing resources around them. Many studies of Olduvai Gorge during Pliocene–Pleistocene times have revealed the presence of precession-driven wet–dry cycles atop a general aridification trend, though may underestimate the impact of local-scale conditions on early hominins, who likely experienced a varied and more dynamic landscape. Fossil lipid biomarkers from ancient plants and microbes encode information about their surroundings via their molecular structures and composition, and thus can shed light on past environments. Here, we employ fossil lipid biomarkers to study the paleolandscape at Olduvai Gorge at the emergence of the Acheulean technology, 1.7 Ma, through the Lower Augitic Sandstones layer. In the context of the expansion of savanna grasslands, our results represent a resource-rich mosaic ecosystem populated by groundwater-fed rivers, aquatic plants, angiosperm shrublands, and edible plants. Evidence of a geothermally active landscape is reported via an unusual biomarker distribution consistent with the presence of hydrothermal features seen today at Yellowstone National Park. The study of hydrothermalism in ancient settings and its impact on hominin evolution has not been addressed before, although the association of thermal springs in the proximity of archaeological sites documented here can also be found at other localities. The hydrothermal features and resources present at Olduvai Gorge may have allowed early hominins to thermally process edible plants and meat, supporting the possibility of a prefire stage of human evolution.

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Section: Resultsmentioning

confidence: 99%

Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma

Sistiaga

Husain

Uribelarrea

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…The analysis of the polar lipid fraction in our samples illuminates this phenomenon. Samples collected from the LAS layer show a very unusual distribution of functionalized lipids, including monoalkyl glycerol monoethers (MAGEs), which have been often interpreted as biomarkers for sulphate-reducing bacteria (SRB) and/or thermophilic organisms [45][46][47] , among other possible biological sources [48][49][50] . These glycerol ether lipids are often present in high concentrations at marine hydrothermal vents and cold seeps 51 , and in terrestrial geothermal sediments 46,47,52 .…”

Section: Resultsmentioning

confidence: 99%

“…MAGEs are the predominant compound class in our alcohol fraction, constituting more than 80% of some of the samples (Fig.4D). A suite of MAGEs ranging from C15 to C19 with straight, branched, and unsaturated hydrocarbon chains dominated by the n-C16 MAGE followed by me-C17:0, which has been linked in the past to the activity of SRB, more specifically from the genus Desulfobacter or Actinomycetes 49,53 . MAGE distributions can be visualized in GC-MS analyses based on their predominant 205 Da fragment ion.…”

Section: Resultsmentioning

confidence: 99%

“…MAGE distributions can be visualized in GC-MS analyses based on their predominant 205 Da fragment ion. Individual MAGE homologues and isomers were identified using elution order and full scan mass spectra (SI2.B) MAGEs identified in soils from non-SRB origin are often dominated by i-C15 and n-C15 49,50 which are present in very low concentrations in our samples. Although our samples are mostly dominated by nC16:0 and Me-C17:0, LAS 1, 3-4, 7-8, and 12-13, contain significant amounts of MAGEs with a carbon chain length >17.…”

Section: Resultsmentioning

confidence: 99%

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The role of tectonics and hydrothermalism in early human evolution at Olduvai Gorge

Sistiaga

Husain

Uribelarrea

et al. 2019

Preprint

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Hominin encephalization has been at the centre of debates concerning human evolution with a consensus on a greater role for improved dietary quality. To sustain the energetic demands of larger brains, cooking was likely essential for increasing the digestibility and energy gain of meat and readily available, yet toxic starches. Here, we present the oldest geochemical evidence for a landscape influenced by tectonic activity and hydrothermal features that potentially shaped early hominin behaviour at Olduvai Gorge. Although use of fire at this time is controversial, hot springs may have provided an alternative way to thermally process dietary resources available in the 1.7 Myo Olduvai wetland. Our data supports the presence of an aquatic-dominated landscape with hydrothermal features that offered hominins new opportunities to hunt and cook readily available tubers and herbivore prey at the emergence of the Acheulean technology. Future studies should further examine whether hydrothermalism similarly influenced other critical aspects of human evolution.

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“…A significant negative correlation between the iso to anteiso ratio of 1- O -MAGEs and soil pH was observed during the study of Chinese soils, but no relationship between the two parameters was evidenced for lake sediments ( Yang et al, 2015 ). An effect of pH on branching of MAGEs and DAGEs may thus be restricted to environments characterized by large intervals of pH, such as soils ( Yang et al, 2015 ) or extreme environments ( Kaur et al, 2015 ), and eventually be used to distinguish different type of paleoenvironments ( Wang and Xu, 2016 ). Additional culture experiments focusing on the influence of pH on the AGE composition of bacteria undoubtedly deserve investigation.…”

Section: Resultsmentioning

confidence: 99%

Temperature-Dependent Alkyl Glycerol Ether Lipid Composition of Mesophilic and Thermophilic Sulfate-Reducing Bacteria

et al. 2017

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The occurrence of non-isoprenoid alkyl glycerol ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid content of two mesophilic (Desulfatibacillum aliphaticivorans and Desulfatibacillum alkenivorans) and one thermophilic (Thermodesulfobacterium commune) sulfate-reducing bacteria—whose membranes are mostly composed of ether lipids—was investigated as a function of growth temperature (20–40°C and 54–84°C, respectively). For all strains, the cellular lipid content was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl glycerols, monoalkyl glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-2 vs sn-1 monoalkyl glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong linear correlations observed between different ratios of alkyl glycerols and temperature allow to hypothesize the use of these specific lipids as indicators of temperature changes in the environment.

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Distribution and source of 1-O-monoalkyl glycerol ethers in the Yellow River and Bohai Sea

Cited by 9 publications

References 53 publications

Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma

Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma

The role of tectonics and hydrothermalism in early human evolution at Olduvai Gorge

Temperature-Dependent Alkyl Glycerol Ether Lipid Composition of Mesophilic and Thermophilic Sulfate-Reducing Bacteria

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