(Table 1) Lipid yields for samples across the Cretaceous/Tertiary boundary in DSDP Hole 86-577

Core samples of calcareous sediments taken from above and below the proposed Cretaceous/Tertiary boundary (Sample 577-12-5, 130 cm) were examined for geochemical evidence of the mass extinctions and faunal successions that marked this period. The lipid compositions of the six core samples examined were virtually identical and were characterized by a large component of unresolved naphthenic hydrocarbons and a homologous series of an/mo-alkanes, both presumably of bacterial origin. The results of this preliminary study suggest that the lipids of sediments deposited over a several million year period encompassing the Cretaceous-Tertiary extinctions have been almost completely recycled by bacterial metabolism, which occurred under oxic depositional and/or diagenetic conditions and which left a unique bacterial signature with only minor traces of the original sedimentary lipids.

Lipid analytic of environmental and cultural samples

Membrane lipids of marine planktonic archaea have provided unique insights into archaeal ecology and paleoceanography. However, past studies of archaeal lipids in suspended particulate matter (SPM) and sediments mainly focused on a small class of fully saturated glycerol dibiphytanyl glycerol tetraether (GDGT) homologues identified decades ago. The apparent low structural diversity of GDGTs is in strong contrast to the high diversity of metabolism and taxonomy among planktonic archaea. Furthermore, adaptation of archaeal lipids in the deep ocean remains poorly constrained. We report the archaeal lipidome in SPM from diverse oceanic regimes. We extend the known inventory of planktonic archaeal lipids to include numerous unsaturated archaeal ether lipids (uns-AELs). We further reveal i) different thermal regulations and polar headgroup compositions of membrane lipids between the epipelagic (<= 100 m) and deep (> 100 m) populations of archaea; ii) stratification of unsaturated GDGTs with varying redox conditions; and iii) enrichment of tetra-unsaturated archaeol and fully saturated GDGTs in epipelagic and deep oxygenated waters, respectively. Such stratified lipid patterns are consistent with the typical distribution of archaeal phylotypes in marine environments. We thus provide an ecological context for GDGT-based paleoclimatology and bring about the potential use of uns-AELs as biomarkers for planktonic Euryarchaeota. This article is protected by copyright. All rights reserved.