The Neanderthal Meal: A New Perspective Using Faecal Biomarkers

Neanderthal dietary reconstructions have, to date, been based on indirect evidence and may underestimate the significance of plants as a food source. While zooarchaeological and stable isotope data have conveyed an image of Neanderthals as largely carnivorous, studies on dental calculus and scattered palaeobotanical evidence suggest some degree of contribution of plants to their diet. However, both views remain plausible and there is no categorical indication of an omnivorous diet. Here we present direct evidence of Neanderthal diet using faecal biomarkers, a valuable analytical tool for identifying dietary provenance. Our gas chromatography-mass spectrometry results from El Salt (Spain), a Middle Palaeolithic site dating to ca. 50,000 yr. BP, represents the oldest positive identification of human faecal matter. We show that Neanderthals, like anatomically modern humans, have a high rate of conversion of cholesterol to coprostanol related to the presence of required bacteria in their guts. Analysis of five sediment samples from different occupation floors suggests that Neanderthals predominantly consumed meat, as indicated by high coprostanol proportions, but also had significant plant intake, as shown by the presence of 5β-stigmastanol. This study highlights the applicability of the biomarker approach in Pleistocene contexts as a provider of direct palaeodietary information and supports the opportunity for further research into cholesterol metabolism throughout human evolution.NASA Astrobiology Institute (Grant NNA13AA90A

2-Methylhopanoids are maximally produced in akinetes of Nostoc punctiforme: geobiological implications

2-Methylhopanes, molecular fossils of 2-methylbacteriohopanepolyol (2-MeBHP) lipids, have been proposed as biomarkers for cyanobacteria, and by extension, oxygenic photosynthesis. However, the robustness of this interpretation is unclear, as 2-methylhopanoids occur in organisms besides cyanobacteria and their physiological functions are unknown. As a first step toward understanding the role of 2-MeBHP in cyanobacteria, we examined the expression and intercellular localization of hopanoids in the three cell types of Nostoc punctiforme: vegetative cells, akinetes, and heterocysts. Cultures in which N. punctiforme had differentiated into akinetes contained approximately 10-fold higher concentrations of 2-methylhopanoids than did cultures that contained only vegetative cells. In contrast, 2-methylhopanoids were only present at very low concentrations in heterocysts. Hopanoid production initially increased threefold in cells starved of nitrogen but returned to levels consistent with vegetative cells within 2 weeks. Vegetative and akinete cell types were separated into cytoplasmic, thylakoid, and outer membrane fractions; the increase in hopanoid expression observed in akinetes was due to a 34-fold enrichment of hopanoid content in their outer membrane relative to vegetative cells. Akinetes formed in response either to low light or phosphorus limitation, exhibited the same 2-methylhopanoid localization and concentration, demonstrating that 2-methylhopanoids are associated with the akinete cell type per se. Because akinetes are resting cells that are not photosynthetically active, 2-methylhopanoids cannot be functionally linked to oxygenic photosynthesis in N. punctiforme.United States. National Aeronautics and Space Administration (NASA Exobiology and Astrobiology Programs)Howard Hughes Medical Institute (Investigator

Carbon Oxidation State in Microbial Polar Lipids Suggests Adaptation to Hot Spring Temperature and Redox Gradients

The influence of oxidation-reduction (redox) potential on the expression of biomolecules is a topic of ongoing exploration in geobiology. In this study, we investigate the novel possibility that structures and compositions of lipids produced by microbial communities are sensitive to environmental redox conditions. We extracted lipids from microbial biomass collected along the thermal and redox gradients of four alkaline hot springs in Yellowstone National Park (YNP) and investigated patterns in the average oxidation state of carbon (ZC), a metric calculated from the chemical formulae of lipid structures. Carbon in intact polar lipids (IPLs) and their alkyl chains becomes more oxidized (higher ZC) with increasing distance from each of the four hot spring sources. This coincides with decreased water temperature and increased concentrations of oxidized inorganic solutes, such as dissolved oxygen, sulfate, and nitrate. Carbon in IPLs is most reduced (lowest ZC) in the hot, reduced conditions upstream, with abundance-weighted ZC values between −1.68 and −1.56. These values increase gradually downstream to around −1.36 to −1.33 in microbial communities living between 29.0 and 38.1◦C. This near-linear increase in ZC can be attributed to a shift from ether-linked to ester-linked alkyl chains, a decrease in average aliphatic carbons per chain (nC), an increase in average degree of unsaturation per chain (nUnsat), and increased cyclization in tetraether lipids. The ZC of lipid headgroups and backbones did not change significantly downstream. Expression of lipids with relatively reduced carbon under reduced conditions and oxidized lipids under oxidized conditions may indicate microbial adaptation across environmental gradients in temperature and electron donor/acceptor supply

Organic geochemistry of the early Toarcian oceanic anoxic event in Hawsker Bottoms, Yorkshire, England

A comprehensive organic geochemical investigation of the Hawsker Bottoms outcrop section in Yorkshire, England has provided new insights about environmental conditions leading into and during the Toarcian oceanic anoxic event (T-OAE; ~183 Ma). Rock-Eval and molecular analyses demonstrate that the section is uniformly within the early oil window. Hydrogen index (HI), organic petrography, polycyclic aromatic hydrocarbon (PAH) distributions, and tricyclic terpane ratios mark a shift to a lower relative abundance of terrigenous organic matter supplied to the sampling locality during the onset of the T-OAE and across a lithological transition. Unlike other ancient intervals of anoxia and extinction, biomarker indices of planktonic community structure do not display major changes or anomalous values. Depositional environment and redox indicators support a shift towards more reducing conditions in the sediment porewaters and the development of a seasonally stratified water column during the T-OAE. In addition to carotenoid biomarkers for green sulfur bacteria (GSB), we report the first occurrence of okenane, a marker of purple sulfur bacteria (PSB), in marine samples younger than ~1.64 Ga. Based on modern observations, a planktonic source of okenane's precursor, okenone, would require extremely shallow photic zone euxinia (PZE) and a highly restricted depositional environment. However, due to coastal vertical mixing, the lack of planktonic okenone production in modern marine sulfidic environments, and building evidence of okenone production in mat-dwelling Chromatiaceae, we propose a sedimentary source of okenone as an alternative. Lastly, we report the first parallel compound-specific δ[superscript 13]C record in marine- and terrestrial-derived biomarkers across the T-OAE. The δ[superscript 13]C records of short-chain n-alkanes, acyclic isoprenoids, and long-chain n -alkanes all encode negative carbon isotope excursions (CIEs), and together, they support an injection of isotopically light carbon that impacted both the atmospheric and marine carbon reservoirs. To date, molecular δ[superscript 13]C records of the T-OAE display a negative CIE that is smaller in magnitude compared to the bulk organic δ[superscript 13]C excursion. Although multiple mechanisms could explain this observation, our molecular, petrographic, and Rock-Eval data suggest that variable mixing of terrigenous and marine organic matter is an important factor affecting the bulk organic δ[superscript 13]C records of the T-OAE.NASA Astrobiology InstituteExobiology Program (U.S.)National Science Foundation (U.S.). Graduate Research Fellowshi

Algoriphagus machipongonensis sp. nov., co-isolated with a colonial choanoflagellate

A Gram-negative, non-motile, non-spore-forming bacterial strain, PR1[superscript T], was isolated from a mud core sample containing colonial choanoflagellates near Hog Island, Virginia, USA. Strain PR1[superscript T] grew optimally at 30 °C and with 3 % (w/v) NaCl. Strain PR1[superscript T] contained MK-7 as the major menaquinone as well as carotenoids but lacked pigments of the flexirubin-type. The predominant fatty acids were iso-C15 : 0 (29.4 %), iso-C17 : 1ω9c (18.5 %) and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c; 11.3 %). The major polar lipids detected in strain PR1[superscript T] were phosphatidylethanolamine, an unknown phospholipid, an aminophospholipid, an aminolipid and two lipids of unknown character. The DNA G+C content was 38.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain PR1[superscript T] fell within the cluster comprising the genus Algoriphagus and was most closely related to Algoriphagus halophilus JC 2051[superscript T] (95.4 % sequence similarity) and Algoriphagus lutimaris S1-3[superscript T] (95.3 % sequence similarity). The 16S rRNA gene sequence similarity between strain PR1[superscript T] and the type strains of other species of the genus Algoriphagus were in the range 91–95 %. Differential phenotypic properties and phylogenetic and genetic distinctiveness of strain PR1[superscript T] demonstrated that this strain was distinct from other members of the genus Algoriphagus, including its closest relative, A. halophilus. Based on phenotypic, chemotaxonomic, phylogenetic and genomic data, strain PR1[superscript T] should be placed in the genus Algoriphagus as a representative of a novel species, for which the name Algoriphagus machipongonensis sp. nov. is proposed. The type strain is PR1[superscript T] ( = ATCC BAA-2233[superscript T]  = DSM 24695[superscript T]).Gordon and Betty Moore Foundation (Investigator Award (581))National Institutes of Health (U.S.) (NIH National Research Service Award and Fellowship grant (5F32GM086054))United States. National Aeronautics and Space Administration (NASA Astrobiology Institute (NNA08CN84A

The alkaloids of some Australian and New Guinea plants

Four plants belonging to three genera, Cinnamomum (Lauraceae), Mitrella (Annonaceae) and Marsdenia (Asclepiadaceae), have been examined and their main alkaloid constituents identified. The bark of an unnamed New Guinea Cinnamomum species, designated by the herbarium voucher number T.G.H. 13,077, yielded two new 1-benzyltetrahydroisoquinoline alkaloids, cinnamolaurine and norcinnamolaurine, together with the known alkaloids corydine, norisocorydine and reticuline. The leaves of the same species were found to contain corydine and reticuline as the major constituents together with traces of cinnamolaurine. Camphor was identified as a neutral component of the leaves. The structure 1-(41 -hydroxybenzyl)-6,7-methylenedioxy- 2-methyl-1,2,3,4-tetrahydroisoquinoline was assigned to cinnamolaurine on the basis of spectroscopic evidence and this was confirmed by synthesis of the racemate. The structure of norcinnamolaurine was deduced from spectroscopic evidence and was confirmed by the formation of cinnamolaurine on N-methylation and also by synthesis of its racemate. Both cinnamolaurine and norcinnamolaurine were shown to belong to the D series of benzylisoquinoline alkaloids. Cinnamomum laubattii F. Muell, a Queensland species, was found to contain reticuline as the only major alkaloid. This may be of chemotaxonomic interest since C. camphora, the only other species of the genus which has been examined for alkaloids, also yielded reticuline as a major constituent. Mitrella kentii (B1.) Miq., a New Guinea species belonging to the family Annonaceae, appears to be the first of its genus to be investigated for alkaloids. The known compounds anonaine, asimilobine and liriodenine were identified as the main constituents while a minor one was shown to be 3,9-dihydroxy-2,10-dimethoxytetrahydroprotoberberine, a structure that has not been reported previously. Marsdenia rostrata R.Br., the fourth plant studied, originated from two different collection localities. A sample obtained from the Toonumbar State Forest in Northern N.S.W. was found to contain the known alkaloid anabasine and a new basic ester aglycone which has been identified as a mixture of O-acetyl-O-nicotinoyl sarcostin and the corresponding 5α-dihydrosarcostin derivative. A sample collected from the South Coast of N.S.W. yielded the above ester aglycone mixture and a number of neutral pregnane aglycones, one of which has been tentatively identified as metaplexigenin

Carbon oxidation state in microbial polar lipids suggests adaptation to hot spring temperature and redox gradients

The influence of oxidation-reduction (redox) potential on the expression of biomolecules is a topic of ongoing exploration in geobiology. In this study, we investigate the novel possibility that structures and compositions of lipids produced by microbial communities are sensitive to environmental redox conditions. We extracted lipids from microbial biomass collected along the thermal and redox gradients of four alkaline hot springs in Yellowstone National Park (YNP) and investigated patterns in the average oxidation state of carbon (ZC), a metric calculated from the chemical formulae of lipid structures. Carbon in intact polar lipids (IPLs) and their alkyl chains becomes more oxidized (higher ZC) with increasing distance from each of the four hot spring sources. This coincides with decreased water temperature and increased concentrations of oxidized inorganic solutes, such as dissolved oxygen, sulfate, and nitrate. Carbon in IPLs is most reduced (lowest ZC) in the hot, reduced conditions upstream, with abundance-weighted ZC values between −1.68 and −1.56. These values increase gradually downstream to around −1.36 to −1.33 in microbial communities living between 29.0 and 38.1°C. This near-linear increase in ZC can be attributed to a shift from ether-linked to ester-linked alkyl chains, a decrease in average aliphatic carbons per chain (nC), an increase in average degree of unsaturation per chain (nUnsat), and increased cyclization in tetraether lipids. The ZC of lipid headgroups and backbones did not change significantly downstream. Expression of lipids with relatively reduced carbon under reduced conditions and oxidized lipids under oxidized conditions may indicate microbial adaptation across environmental gradients in temperature and electron donor/acceptor supply. ©2019NSF (grant no. EAR1123649)NSF (grant no. EAR-1529963)NASA Exobiology (grant no. NNX16AJ61G

Carbon Oxidation State in Microbial Polar Lipids Suggests Adaptation to Hot Spring Temperature and Redox Gradients

The influence of oxidation-reduction (redox) potential on the expression of biomolecules is a topic of ongoing exploration in geobiology. In this study, we investigate the novel possibility that structures and compositions of lipids produced by microbial communities are sensitive to environmental redox conditions. We extracted lipids from microbial biomass collected along the thermal and redox gradients of four alkaline hot springs in Yellowstone National Park (YNP) and investigated patterns in the average oxidation state of carbon (ZC), a metric calculated from the chemical formulae of lipid structures. Carbon in intact polar lipids (IPLs) and their alkyl chains becomes more oxidized (higher ZC) with increasing distance from each of the four hot spring sources. This coincides with decreased water temperature and increased concentrations of oxidized inorganic solutes, such as dissolved oxygen, sulfate, and nitrate. Carbon in IPLs is most reduced (lowest ZC) in the hot, reduced conditions upstream, with abundance-weighted ZC values between −1.68 and −1.56. These values increase gradually downstream to around −1.36 to −1.33 in microbial communities living between 29.0 and 38.1◦C. This near-linear increase in ZC can be attributed to a shift from ether-linked to ester-linked alkyl chains, a decrease in average aliphatic carbons per chain (nC), an increase in average degree of unsaturation per chain (nUnsat), and increased cyclization in tetraether lipids. The ZC of lipid headgroups and backbones did not change significantly downstream. Expression of lipids with relatively reduced carbon under reduced conditions and oxidized lipids under oxidized conditions may indicate microbial adaptation across environmental gradients in temperature and electron donor/acceptor supply

Recovery of fatty acids from mineralogic mars analogs by TMAH thermochemolysis for the sample analysis at Mars wet chemistry experiment on the Curiosity rover

The Mars Curiosity rover carries a diverse instrument payload to characterize habitable environments in the sedimentary layers of Aeolis Mons. One of these instruments is Sample Analysis at Mars (SAM), which contains a mass spectrometer that is capable of detecting organic compounds via pyrolysis gas chromatography mass spectrometry (py-GC-MS). To identify polar organic molecules, the SAM instrument carries the thermochemolysis reagent tetramethylammonium hydroxide (TMAH) in methanol (hereafter referred to as TMAH). TMAH can liberate fatty acids bound in macromolecules or chemically bound monomers associated with mineral phases and make these organics detectable via gas chromatography mass spectrometry (GC-MS) by methylation. Fatty acids, a type of carboxylic acid that contains a carboxyl functional group, are of particular interest given their presence in both biotic and abiotic materials. This work represents the first analyses of a suite of Mars-analog samples using the TMAH experiment under select SAM-like conditions. Samples analyzed include iron oxyhydroxides and iron oxyhydroxysulfates, a mixture of iron oxides/oxyhydroxides and clays, iron sulfide, siliceous sinter, carbonates, and shale. The TMAH experiments produced detectable signals under SAM-like pyrolysis conditions when organics were present either at high concentrations or in geologically modern systems. Although only a few analog samples exhibited a high abundance and variety of fatty acid methyl esters (FAMEs), FAMEs were detected in the majority of analog samples tested. When utilized, the TMAH thermochemolysis experiment on SAM could be an opportunity to detect organic molecules bound in macromolecules on Mars. The detection of a FAME profile is of great astrobiological interest, as it could provide information regarding the source of martian organic material detected by SAM. ©201

Microaerobic steroid biosynthesis and the molecular fossil record of Archean life

The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth’s evolution. Among the various geochemical proxies for the presence of O2 in the environment, molecular fossils offer a unique record of O2 where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O2 requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O2 concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O2. In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today.Agouron InstituteUnited States. National Aeronautics and Space Administration (Astrobiology Institute)Howard Hughes Medical InstituteUnited States. Office of Naval Research (National Defense Science and Engineering Graduate Fellowship)National Science Foundation (U.S.) (Graduate Fellowship