Woods Hole Oceanographic Institution

»Bioavailability of soil organic matter and microbial community dynamics upon permafrost thaw
»7000 years of virus-host molecular dynamics in the Black Sea
»Preservation potential of ancient DNA in Pleistocene marine sediments: Implications for paleoenvironmental reconstructions
»Source-specific variability in post-depositional DNA preservation with potential implications for DNA-based paleecological records
»Exploring preserved ancient dinoflagellalte and haptophyte DNA signatures to infer ecological and environmental conditions during sapropel S1 formation in the eastern Mediterranean
»Ancient DNA in lake sediment records
»Vertical distribution of metabolically active eukaryotes in the water column and sediments of the Black Sea
»DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene
»Diversity of Archaea and potential for crenarchaeotal nitrification of group 1.1a in the rivers Rhine and TĂȘt
»Holocene sources of fossil BHPs
»An unusual 17[α],21[β](H)-bacteriohopanetetrol in Holocene sediments from Ace Lake (Antarctica)
»Holocene sources of organic matter in Antarctic fjord
»Variations in spatial and temporal distribution of Archaea in the North Sea
»Archaeal nitrifiers in the Black Sea
»Pleistocene Mediterranean sapropel DNA
»Rapid sulfurisation of highly branched isoprenoid (HBI) alkenes in sulfidic Holocene sediments
»Aerobic and anaerobic methanotrophs in the Black Sea water column
»Fossil DNA in Cretaceous Black Shales: Myth or Reality?
»Sulfur and methane cycling during the Holocene in Ace Lake (Antarctica)
»Ancient algal DNA in the Black Sea
»Archaeal nitrification in the ocean
»Characterization of microbial communities found in the human vagina by analysis of terminal restriction fragment length polymorphisms of 16S rRNA genes
»Biomarker and 16S rDNA evidence for anaerobic oxidation of methane and related carbonate precipitation in deep-sea mud volcanoes of the Sorokin Trough, Black Sea
»Temperature-dependent variation in the distribution of tetraether membrane lipids of marine Crenarchaeota: Implications for TEX86 paleothermometry
»Paleoecology of algae in Ace Lake
»Evolution of the methane cycle in Ace Lake (Antarctica) during the Holocene: Response of methanogens and methanotrophs to environmental change
»Ongoing modification of Mediterranean Pleistocene sapropels mediated by prokaryotes.
»Microbial communities in the chemocline of a hypersaline deep-sea basin (Urania basin, Mediterranean Sea)
»Functional exoenzymes as indicators of metabolically active bacteria in 124,000-year-old sapropel layers of the Eastern Mediterranean Sea
»Specific detection of different phylogenetic groups of chemocline bacteria based on PCR and denaturing gradient gel electrophoresis of 16S rRNA gene fragments
»Analysis of subfossil molecular remains of purple sulfur bacteria in a lake sediment
»Effects of nitrate availability and the presence of Glyceria maxima the composition and activity of the dissimilatory nitrate-reducing bacterial community
»Microbial activities and populations in upper sediment and sapropel layers

Wuchter, C., S. Schouten, M. J. L. Coolen and J. S. Sinninghe Damsté,, Temperature-dependent variation in the distribution of tetraether membrane lipids of marine Crenarchaeota: Implications for TEX86 paleothermometry, Paleoceanography, 19(4), PA4028, doi:10.1029/2004PA001041, 2004

Recently, a new geochemical temperature proxy, the TEX86, was introduced. This proxy is based on the number of cyclopentane moieties in the glycerol dialkyl glycerol tetraethers (GDGTs) of the membrane lipids of marine Crenarchaeota, which changes as a response to temperature. However, until now, only sediment data have been used to establish this proxy, and experimental work is missing. We performed mesocosm studies with marine Crenarchaeota incubated at temperatures ranging from 5 to 35°C and salinities of 27 and 35‰ to test the validity of the TEX86 proxy. Growth of marine Crenarchaeota in these mesocosms was evident from the substantial increase in the concentration of marine Crenarchaeotal membrane lipids with amounts up to 3400 ng/L. With increasing temperature, an increase in the number of cyclopentane moieties in the crenarchaeotal membrane lipids was observed. Different salinities did not show any effect on the GDGT distribution. The TEX86 showed a significant linear correlation to incubation temperature: TEX86 = 0.015 × T + 0.10 (r2 = 0.79). This equation has a similar slope to the correlation obtained from core tops but differs in the intersection (TEX86 = 0.015 × T + 0.28, r2 = 0.92). This difference is mainly determined by the smaller amount of the regioisomer of crenarchaeol in the incubation series compared to core top samples. These incubation experiments indicates that water temperature is indeed the major controlling factor for the membrane distribution of marine Crenarchaeota and confirms that the TEX86 proxy depends on a physiological response to regulate membrane fluidity. Full text of article can be viewed here.

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