... abundance: they amplify the genetic signature, which allows detection at much lower concentrations than necessary for lipid analysis. Although it is becoming clear that nonthermophilic crenarchaeota are not restricted to marine environments, but also live in lakes, GDGTs have not previously been reported...

...Figure 1. Plots showing relationship of GDGT (glycerol dialkyl glycerol tetraethers) parameters (CBT, cyclization ratio of branched GDGTs, and R i/b ) with pH values in modern Chinese soils and with local mean annual precipitation (MAP). Alkaline soils (pH > 7.5) and enhanced aridity (MAP...

...Table 1.— GDGT-based proxy values for McAbee samples. See Online Supplemental File Table S3 for equations and descriptions for each proxy. Abbreviations: MS = tuffaceous mudstone; S = laminated shale; MAAT soil = mean annual air temperature over the soil (°C). ...

... we used a new method for estimating continental MAAT that has recently been developed ( Weijers et al., 2007a ). This method is based on the distribution of branched glycerol dialkyl glycerol tetra-ethers (GDGTs), membrane lipids derived from anaerobic nonphotosynthetic bacteria thriving in soils...

... of topography. Paleoelevation was determined by reconstructing the change in the hydrogen isotopic composition of precipitation (ΔδD precip ) and mean annual temperature (Δ T GDGT ) (glycerol dialkyl glycerol tetraethers) from the isotopic composition of fossil angiosperm leaf n -alkanes and the distribution...

.... , Sinninghe Damsté , J.S. , and Villanueva , L. , 2020 , The absence of intact polar lipid-derived GDGTs in marine waters dominated by marine group II: Implications for lipid biosynthesis in Archaea : Scientific Reports , v. 10 , 294, https://doi.org/10.1038/s41598-019-57035-0 . Capella , W...

... ; Sabino et al. 2020 ; Fig. 2 ), which accordingly correspond to the gypsum bed in cycle PLG1 of Perales ( Fig. 2 ; Manzi et al. 2013 ). water-column stratification marine conditions archaeol GDGTs lycopane oxygen depletion redox zonation During Messinian time (7.25–5.33 Ma...

... chromatography–mass spectrometry technique have enabled the identification and quantification of glycerol dialkyl glycerol tetraethers (GDGTs), a range of microbial lipid biomarkers, in modern and ancient environments ( Hopmans et al., 2004 ; Schouten et al., 2013 ). Here, we present the first sequential GDGT...

... group synthesizes archaeal tetraether lipids, glycerol dibiphytanyl glycerol tetraethers (GDGTs) with zero to four cyclopentane rings, and the specific thaumarchaeotal lipid biomarker crenarchaeol, which has four cyclopentane and one cyclohexane ring in its structure. These discoveries paved the way...

... to ca. 17 Ma, when apparent large changes in p CO 2 (579 ppm to 266 ppm) were not accompanied by changes in SST ( Figs. 2 and 3 ). However, this interval also has large variability in GDGT source indices (Fig. DR6). It thus may represent a time when local factors at DSDP Site 608, such as changes...

.... Hexatriacontane, 19-methyleicosanoic acid, tridecyl alcohol, and C 46 glycerol trialkyl glycerol tetraether (C 46 GDGT) were used as internal standards. Total lipid extracts were dried with anhydrous sodium sulfate, and an aliquot of total lipid extracts was treated with 6% potassium hydroxide (w/v) in methanol...

... trimethylsilyl ethers. Blanks were run to ensure that no contamination was introduced during the extraction and separation procedures. A second aliquot of the TLE of nodule B was used for glycerol dialkyl glycerol tetraether (GDGT) analysis and was separated into a polar and an apolar fraction using Al 2 O 3...

... 10 Myr. To do so, surface and subsurface temperature records from IODP Site U1338 (EEP) ( Fig. 1 ) are generated from both alkenones ( ) produced by coccolithophores (marine unicellular haptophyte algae, Brassell et al. 1986 ) and glycero-dialkyl glycerol-tetraethers (GDGTs, TEX H 86 ) produced...

... of Core 69R, TEX 86 values gradually decrease to ∼0.84 (interval D; average 0.87; 1σ = 0.03, n = 37). In order to assess the origins of the isoGDGTs, other GDGT-based indices (e.g., branched and isoprenoid tetraether [BIT] index, methane index, relative abundance of GDGT-0 [%GDGT-0], ring index [|ΔRI...

..., 1988, 1989, 1990) and Perch-Nielsen (1985), except for Dictyococcites and Cribrocentrum , for which we followed Agnini et al. (2014). Glycerol dialkyl glycerol tetraether (GDGT) lipids were extracted from ~10 g aliquots of powdered, freeze-dried sediment (47 samples) with a Dionex accelerated...