ORCID Profile
0000-0003-2136-3508
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Publisher: Springer Berlin Heidelberg
Date: 2008
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 12-2020
Publisher: Wiley
Date: 16-07-2014
DOI: 10.1111/GBI.12094
Abstract: The present study investigated the influence of abiotic conditions on microbial mat communities from Shark Bay, a World Heritage area well known for a erse range of extant mats presenting structural similarities with ancient stromatolites. The distributions and stable carbon isotopic values of lipid biomarkers [aliphatic hydrocarbons and polar lipid fatty acids (PLFAs)] and bulk carbon and nitrogen isotope values of biomass were analysed in four different types of mats along a tidal flat gradient to characterize the microbial communities and systematically investigate the relationship of the above parameters with water depth. Cyanobacteria were dominant in all mats, as demonstrated by the presence of diagnostic hydrocarbons (e.g. n-C17 and n-C17:1). Several subtle but important differences in lipid composition across the littoral gradient were, however, evident. For instance, the shallower mats contained a higher diatom contribution, concordant with previous mat studies from other locations (e.g. Antarctica). Conversely, the organic matter (OM) of the deeper mats showed evidence for a higher seagrass contribution [high C/N, 13C-depleted long-chain n-alkanes]. The morphological structure of the mats may have influenced CO2 diffusion leading to more 13C-enriched lipids in the shallow mats. Alternatively, changes in CO2 fixation pathways, such as increase in the acetyl COA-pathway by sulphate-reducing bacteria, could have also caused the observed shifts in δ13C values of the mats. In addition, three smooth mats from different Shark Bay sites were analysed to investigate potential functional relationship of the microbial communities with differing salinity levels. The C25:1 HBI was identified in the high salinity mat only and a lower abundance of PLFAs associated with diatoms was observed in the less saline mats, suggesting a higher abundance of diatoms at the most saline site. Furthermore, it appeared that the most and least saline mats were dominated by autotrophic biomass using different CO2 fixation pathways.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier BV
Date: 03-2019
Publisher: Elsevier BV
Date: 03-2018
Publisher: Elsevier BV
Date: 05-2018
Publisher: Cambridge University Press (CUP)
Date: 07-2014
DOI: 10.1016/J.YQRES.2014.02.005
Abstract: Branched glycerol dialkyl glycerol tetraether (GDGT) distributions observed in a sediment core from Lake McKenzie were utilized to quantitatively reconstruct the pattern of mean annual air temperature (MAAT) from coastal subtropical eastern Australia between 37 and 18.3 cal ka BP and 14.0 cal ka BP to present. Both the reconstructed trend and litude of MAAT changes from the top of the sediment core were nearly identical to a local instrumental MAAT record from Fraser Island, providing confidence that in this sediment core branched GDGTs could be used to produce a quantitative record of past MAAT. The reconstructed trend of MAAT during 37 to 18.3 cal ka BP and timing of the Last Glacial Maximum (LGM) in the Lake McKenzie record were in agreement with previously published nearby marine climate records. The litude of lower-than-present MAAT during the LGM potentially provides information on the latitude of separation of the Tasman Front from the East Australian current in the subtropical western Pacific. The Lake McKenzie record shows an earlier onset of near modern day warm temperatures in the early Holocene compared to marine records and the presence of a warmer than present day period during the mid-Holocene.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Frontiers Media SA
Date: 10-05-2023
DOI: 10.3389/FMARS.2023.1089746
Abstract: Mesophotic corals live at ~30-150 m depth and can sustain metabolic processes under light-limited conditions by enhancing autotrophy through specialized photoadaptations or increasing heterotrophic nutrient acquisition. These acclimatory processes are often species-specific, however mesophotic ecosystems are largely unexplored and acclimation limits for most species are unknown. This study examined mesophotic coral ecosystems using a remotely operated vehicle (Ashmore Reef, Western Australia at 40–75m depth) to investigate the trophic ecology of five species of scleractinian coral (from genera Leptoseris , Pachyseris , and Craterastrea ) using stable isotope analyses (δ 13 C and δ 15 N) of host and symbiont tissues and protein concentration. Trophic strategies were analyzed between species and between overall corals s led above and below the end-photic point, where light is only 1% of surface irradiance. Results showed species-specific differences in resource use. Leptoseris hawaiiensis, L. scabra , and P. speciosa had similar Δ 13 C values (δ 13 C host - δ 13 C symbiont) approaching zero (& 0.5 ‰) which indicated greater dependence on symbiont autotrophy. In contrast, Leptoseris glabra and Craterastrea levis had higher Δ 13 C values (1.4 to 3.5 ‰) which indicated a greater reliance on external carbon sources. The latter two species also demonstrated tight nitrogen recycling within the holobiont, exhibiting low Δ 15 N values (host δ 15 N - symbiont δ 15 N =& 0.5 ‰), compared to more autotrophic species (Δ 15 N = & .2 ‰). Some species demonstrated the ability to maintain metabolic processes despite substantially reduced light availability (0.5 – 2% of surface irradiance). This research challenges our knowledge of acclimation limits for many scleractinian corals and contributes novel information for Ashmore Reef, the Western Australia region and mesophotic ecosystems in general, and critically examines common methods used to interpretate trophic ecology with bulk stable isotopes δ 13 C and δ 15 N.
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 06-2016
Publisher: MDPI AG
Date: 06-03-2019
DOI: 10.3390/MIN9030158
Abstract: In the vast majority of fossils, the organic matter is degraded with only an impression or cast of the organism remaining. In rare cases, ideal burial conditions result in a rapid fossilisation with an exceptional preservation of soft tissues and occasionally organic matter. Such deposits are known as Lagerstätten and have been found throughout the geological record. Exceptional preservation is often associated with finely crystalline quartz (e.g., cherts), fine sediments (e.g., muds) or volcanic ashes. Other mechanisms include burial in anoxic/euxinic sediments and in the absence of turbidity or scavenging. Exceptional preservation can also occur when an organism is encapsulated in carbonate cement, forming a concretion. This mechanism involves complex microbial processes, resulting in a supersaturation in carbonate, with microbial sulfate reduction and methane cycling the most commonly suggested processes. In addition, conditions of photic zone euxinia are often found to occur during concretion formation in marine environments. Concretions are ideal for the study of ancient and long-extinct organisms, through both imaging techniques and biomolecular approaches. These studies have provided valuable insights into the evolution of organisms and their environments through the Phanerozoic and have contributed to increasing interest in fields including chemotaxonomy, palaeobiology, palaeoecology and palaeophysiology.
Publisher: Elsevier BV
Date: 02-2004
Publisher: Wiley
Date: 28-08-2008
DOI: 10.1111/J.1556-4029.2008.00798.X
Abstract: Pressure-sensitive adhesive tapes often represent key evidence of crimes such as assault, rape or homicide thus, the development of analytical techniques able to contribute to a detailed characterization of these materials is of forensic importance. The gas chromatography-mass spectrometry (GCMS) analysis of the solvent extractable fractions of a suite of electrical and gaffer adhesive tapes spanning a range of colors and manufacturers identified a number of petroleum-derived hydrocarbons. Molecular and isotopic analyses of hydrocarbon constituents of complex materials have found wide analytical utility including the forensic investigation of oil spills and arson. Here, we investigate the utility of these techniques for characterizing the hydrocarbon composition of pressure-sensitive adhesive tapes for forensic correlation purposes. Subtle distinction of tape s les was evident in the GCMS distribution of several hydrocarbon groups including alkyl-naphthalenes, hopane and sterane biomarkers. Linear discriminant analysis of the abundances of these products provided high level differentiation of tape manufacturer. The distinction of different adhesive tape s les was further extended by measurement of their stable carbon isotopic values. The molecular and isotopic differences of the petroleum content of tapes are consistent with the use of different petroleum materials used in the manufacturing process and demonstrate the benefits of the combined use of complementary oil hydrocarbon characterization approaches. This study reveals the forensic potential of using established petroleum characterization methods for characterizing materials with a petroleum-derived hydrocarbon element.
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 07-2007
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.MARPOLBUL.2022.113791
Abstract: The International Marine Organization 2020 Global Sulfur Cap requires ships to burn fuels with <0.50% S and some countries require <0.10% S in certain Sulfur Emission Control Areas but little is known about these new types of fuels. Using both traditional GC-MS and more advanced chromatographic and mass spectrometry techniques, plus stable isotopic, δ
Publisher: Geological Society of London
Date: 03-02-2014
Abstract: In the northern Perth Basin (Western Australia), the Early Triassic Kockatea Shale is the primary petroleum source rock. Possible source rocks in the Northern Carnarvon Basin are more varied and include the Upper Jurassic Dingo Claystone as well as the Early Triassic Locker Shale. Biomarker analyses were conducted on petroleum s les from these basins to understand the nature of the petroleum systems. Many of the analysed petroleum s les contain carotenoids (okenane, chlorobactane and isorenieratane) derived from photosynthetic sulfur bacteria, suggesting that their source rocks were deposited under conditions of photic zone euxinia (PZE) and/or derived from microbialites. In the northern Perth Basin, the major lithofacies contributing to the source rock are dark coloured mudstones deposited under PZE conditions and/or derived from microbialites. In the southern Perth Basin, the potential source rock is either Permian, Jurassic or Cretaceous in age as indicated by the low concentrations or absence of carotenoids and the Triassic biomarker n -C 33 alkylcyclohexane. There is also a possibility that the Lower Triassic Locker Shale is the source rock of petroleum in the Tubridgi field on the Peedamullah Shelf of the Northern Carnarvon Basin, based on the similarity of biomarkers to Perth Basin petroleum sourced from the Kockatea Shale. However, the possibility of charge from the Upper Jurassic Dingo Claystone cannot be entirely excluded. Supplementary material: biomarker dataset is available at 0.6084/m9.figshare.c.6452153
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 09-2017
Publisher: Springer Science and Business Media LLC
Date: 12-02-2021
DOI: 10.1038/S41598-021-83286-X
Abstract: Groundwaters host vital resources playing a key role in the near future. Subterranean fauna and microbes are crucial in regulating organic cycles in environments characterized by low energy and scarce carbon availability. However, our knowledge about the functioning of groundwater ecosystems is limited, despite being increasingly exposed to anthropic impacts and climate change-related processes. In this work we apply novel biochemical and genetic techniques to investigate the ecological dynamics of an Australian calcrete under two contrasting rainfall periods (LR—low rainfall and HR—high rainfall). Our results indicate that the microbial gut community of copepods and hipods experienced a shift in taxonomic ersity and predicted organic functional metabolic pathways during HR. The HR regime triggered a cascade effect driven by microbes (OM processors) and exploited by copepods and hipods (primary and secondary consumers), which was finally transferred to the aquatic beetles (top predators). Our findings highlight that rainfall triggers ecological shifts towards more deterministic dynamics, revealing a complex web of interactions in seemingly simple environmental settings. Here we show how a combined isotopic-molecular approach can untangle the mechanisms shaping a calcrete community. This design will help manage and preserve one of the most vital but underrated ecosystems worldwide.
Publisher: Wiley
Date: 18-11-2022
DOI: 10.1002/ETC.5489
Abstract: In the present study, we investigated the possibility of identifying the source oils of exposed fish using ratios of bicyclic sesquiterpane (bicyclane) chemical biomarkers. In the event of an oil spill, identification of source oil(s) for assessment, or for litigation purposes, typically uses diagnostic ratios of chemical biomarkers to produce characteristic oil "fingerprints." Although this has been applied in identifying oil residues in sediments, water, and sessile filtering organisms, so far as we are aware this has never been successfully demonstrated for oil-exposed fish. In a 35-day laboratory trial, juvenile Lates calcarifer (barramundi or Asian seabass) were exposed, via the diet (1% w/w), to either a heavy fuel oil or to Montara, an Australian medium crude oil. Two-dimensional gas chromatography with high-resolution mass spectrometry and gas chromatography-mass spectrometry were then used to measure selected ratios of the bicyclanes to examine whether the ratios were statistically reproducibly conserved in the fish tissues. Six diagnostic bicyclane ratios showed high correlation (r
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 02-2010
Publisher: American Chemical Society (ACS)
Date: 29-06-2022
Publisher: Elsevier BV
Date: 08-2016
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 11-2020
Publisher: Wiley
Date: 03-12-2020
DOI: 10.1111/GBI.12421
Publisher: Geological Society of America
Date: 02-2013
DOI: 10.1130/G33492.1
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.CBPC.2021.109253
Abstract: The uptake of metals into the aragonite lattice of the fish otolith (ear-bone) has been used for decades as a historical record of exposure to metals in polluted environments. The relative abundance of two metals in particular, Ni and V, are used in forensic chemical analysis of crude oils to assist in confirming its origin. In this study we investigate the potential for metal accumulation in otoliths to act as a biomarker of exposure to crude oil. Using a 33-day static-renewal laboratory trial design, 56 juvenile Lates calcarifer (commonly known as Asian seabass or barramundi) were fed diets enriched with V (20 mg/kg), Ni (500 mg/kg), Fe (500 mg/kg), and two crude oils with distinctly different metals profiles: a heavy fuel oil (1% w/w) and a typical Australian medium crude (1% w/w). Fish exposed to crude oils showed Ba and Al retained in otoliths in a dose-dependent manner, but fish fed V-, Ni- and Fe-enriched diets showed no metal increase in otoliths, indicating that V, Ni and Fe are not incorporated into the otolith of L. calcarifer via dietary exposure. For crude oils, incorporation into otolith for many metals is likely limited due to porphyrin casing reducing their bioavailability. Principal components analysis (PCA) and subsequent linear discriminatory analysis (LDA) of selected otolith metals demonstrated that, even despite large variability in the metal abundances detected in otolith between in iduals within the test groups (cv = 1.00), it is possible to discriminate between fish exposed to different crude oils using multivariate analysis of their otolith microchemistry.
Publisher: Elsevier BV
Date: 2009
Publisher: Elsevier BV
Date: 2005
Publisher: Springer Netherlands
Date: 2011
Publisher: Wiley
Date: 18-02-2014
Abstract: Modern microbial mats are highly complex and dynamic ecosystems. Diffusive equilibration in thin films (DET) and diffusive gradients in thin films (DGT) s lers were deployed in a modern smooth microbial mat from Shark Bay in order to observe, for the first time, two-dimensional distributions of porewater solutes during day and night time. Two-dimensional sulfide and alkalinity distributions revealed a strong spatial heterogeneity and a minor contribution of sulfide to alkalinity. Phosphate distributions were also very heterogeneous, while iron(II) distributions were quite similar during day and night with a few hotspots of mobilization. Lipid biomarkers from the three successive layers of the mat were also analysed in order to characterize the microbial communities regulating analyte distributions. The major hydrocarbon products detected in all layers included n-alkanes and isoprenoids, whilst other important biomarkers included hopanoids. Phospholipid fatty acid profiles revealed a decrease in cyanobacterial markers with depth, whereas sulfate-reducing bacteria markers increased in abundance in accordance with rising sulfide concentrations with depth. Despite the general depth trends in community structure and physiochemical conditions within the mat, two-dimensional solute distributions showed considerable small-scale lateral variability, indicating that the distributions and activities of the microbial communities regulating these solute distributions were equally heterogeneous and complex.
Publisher: Elsevier BV
Date: 11-2009
Publisher: Springer Science and Business Media LLC
Date: 27-03-2015
DOI: 10.1007/S00248-015-0598-3
Abstract: Modern microbial mats from Shark Bay present some structural similarities with ancient stromatolites thus, the functionality of microbial communities and processes of diagenetic preservation of modern mats may provide an insight into ancient microbial assemblages and preservation. In this study, the vertical distribution of microbial communities was investigated in a well-laminated smooth mat from Shark Bay. Biolipid and compound-specific isotopic analyses were performed to investigate the distribution of microbial communities in four distinct layers of the mat. Biomarkers indicative of cyanobacteria were more abundant in the uppermost oxic layer. Diatom markers (e.g. C25 HBI alkene, C20:4ω6 and C20:5ω3 polar lipid fatty acids (PLFAs)) were also detected in high abundance in the uppermost layer, but also in the deepest layer under conditions of permanent darkness and anoxia, where they probably used NO3 (-) for respiration. CycC19:0, an abundant PLFA of purple sulfur bacteria (PSB), was detected in all layers and presented the most (13)C-depleted values of all PLFAs, consistent with photoautotrophic PSB. Sulfur-bound aliphatic and aromatic biomarkers were detected in all layers, highlighting the occurrence of early sulfurisation which may be an important mechanism in the sedimentary preservation of functional biolipids in living and, thus, also ancient mats.
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 10-2021
Publisher: European Association of Geoscientists & Engineers
Date: 2019
Publisher: Elsevier BV
Date: 05-2016
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.PHYTOCHEM.2009.11.009
Abstract: The n-fatty acids containing an even number of carbons (ECN-n-FAs) in higher plants are biosynthesised by repetitive addition of a two carbon unit from malonyl-ACP. The n-alkanes containing an odd number of carbon atoms (OCN-n-alkanes) are generally formed by the decarboxylation of ECN-n-FAs, but it is unknown how the less abundant even-carbon-numbered alkanes (ECN-n-alkanes) are biosynthesised in higher plants. There is a distinctive compositional pattern of incorporation of stable carbon ((13)C) and hydrogen ((2)H) isotopes in co-existing ECN- and OCN-n-alkanes in leaves of higher plants, such that the OCN n-alkanes are relatively enriched in (13)C but relatively depleted in (2)H against the ECN-n-alkanes. This is consistent with the OCN-n-fatty acids having a propionate precursor which is derived from reduction of pyruvate. A tentative pathway is presented with propionate produced by enzymatic reduction of pyruvate which is then thio-esterified with CoSH (coenzyme A thiol) in the chloroplast to form the terminal precursor molecule propionyl-CoA. This is then repetitively extended/elongated with the 2-carbon unit from malonyl-ACP to form the long chain OCN-n-fatty acids. The anteiso- and iso-alkanes in Nicotiana tabacum leaf waxes have previously been found to be systematically enriched in (13)C compared with the n-alkanes by Grice et al. (2008). This is consistent with the isotopic composition of their putative respective precursors (pyruvate as precursor for n-alkanes, valine for iso-alkanes and isoleucine for anteiso-alkanes). The current study complements that of Grice et al. (2008) and looks at the distribution of hydrogen isotopes. The n-alkanes were found to be more enriched in deuterium ((2)H) than the iso-alkanes which in turn were more enriched than the anteiso-alkanes. We propose therefore that the depletion of (2)H in the iso-alkanes, relative to the n-alkanes is the consequence of accepting highly (2)H-depleted hydrogen atoms from NADPH during their biosynthesis. The anteiso-alkanes are further depleted again because there are three NADPH-derived hydrogen atoms in their precursor isoleucine, as compared with only one NADPH-derived hydrogen in valine, the precursor of the iso-alkanes.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 2019
Publisher: Springer Netherlands
Date: 2011
Publisher: Elsevier BV
Date: 07-2019
Publisher: Elsevier BV
Date: 08-2013
Publisher: Wiley
Date: 06-2004
Publisher: Proceedings of the National Academy of Sciences
Date: 16-11-2020
Abstract: The end-Triassic mass extinction that occurred ∼202 Ma is one of the “Big Five” biotic crises of the Phanerozoic Eon. It is also accompanied by an organic carbon isotopic excursion that has long been interpreted as the result of a global-scale carbon-cycle disruption. Rather than being due to massive inputs of exogenous light carbon into the ocean–atmosphere system, the isotopic excursion is shown here to reflect regional sea-level change that caused a transition from a marine ecosystem to a less saline, shallow-water, microbial-mat environment and resultant changes in the sources of organic matter. The mass extinction that occurred slightly later, caused by abrupt injection of volcanogenic CO 2 , is accompanied by only modest changes in organic carbon isotopic composition.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Informa UK Limited
Date: 10-05-2023
Publisher: Elsevier BV
Date: 12-2022
Publisher: Frontiers Media SA
Date: 16-11-2020
Publisher: Elsevier BV
Date: 02-2013
Publisher: Elsevier BV
Date: 09-2015
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 11-2018
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/BT16109
Abstract: Much of the Australian flora has high flammability. It is therefore of interest whether burning was a feature in the Cretaceous, the geological period in which angiosperms rose to dominance, and in which fossil and molecular evidence suggests the presence of lineages now prominent in regularly burnt habitats. Determining the extent of fire in the Australian Cretaceous is limited by a paucity of surface exposures of strata, and of published reports of definite charcoal from exploration cores. Nevertheless, charcoalified tissues occur much more widely than is currently reported in the international literature, and there are also numerous references to inertinite macerals in Australian Cretaceous coals. Combustion-related hydrocarbons can also be detected in ancient sediments using organic geochemical methods, and we demonstrate the potential of this approach here. Overall, the available evidence is in concert with that from elsewhere on Earth: fire was apparently widespread in the Australian Cretaceous, and can reasonably be invoked as a force that influenced the evolution of modern Australian environments. Just as in extant open, nutrient-limited regions, proteaceous lineages seem to have been important in burnt, open habitats in the Late Cretaceous, perhaps retaining dominance of such niches for million years. However, there is so far no fossil evidence for the Cretaceous presence of Eucalyptus, the principal tree genus of modern Australian fire-prone vegetation.
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.CHROMA.2008.05.030
Abstract: The conversion efficiency of alkanoic, alkenoic, branched, alicyclic, aromatic, keto-substituted, and dioic carboxylic acids to their corresponding butyl esters was compared under different reaction conditions (time, temperature, catalyst). We show that boron trifluoride is generally a more efficient catalyst than sulphuric acid. However, optimum derivatisation conditions vary strongly for different acids and no single derivatisation protocol can be employed without certain losses. Therefore, care must be taken when the simultaneous quantitative analysis of different types of carboxylic acids in one s le is envisaged. Addition of water-scavenging reagents to the reaction mixture caused the formation of artefacts and selectively decreased reaction yields.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 11-2022
Publisher: Elsevier BV
Date: 11-2013
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 08-2018
Publisher: Geological Society of America
Date: 17-01-2020
DOI: 10.1130/G46799.1
Abstract: The Chicxulub crater was formed by an asteroid impact at ca. 66 Ma. The impact is considered to have contributed to the end-Cretaceous mass extinction and reduced productivity in the world’s oceans due to a transient cessation of photosynthesis. Here, biomarker profiles extracted from crater core material reveal exceptional insights into the post-impact upheaval and rapid recovery of microbial life. In the immediate hours to days after the impact, ocean resurge flooded the crater and a subsequent tsunami delivered debris from the surrounding carbonate r . Deposited material, including biomarkers diagnostic for land plants, cyanobacteria, and photosynthetic sulfur bacteria, appears to have been mobilized by wave energy from coastal microbial mats. As that energy subsided, days to months later, blooms of unicellular cyanobacteria were fueled by terrigenous nutrients. Approximately 200 k.y. later, the nutrient supply waned and the basin returned to oligotrophic conditions, as evident from N2-fixing cyanobacteria biomarkers. At 1 m.y. after impact, the abundance of photosynthetic sulfur bacteria supported the development of water-column photic zone euxinia within the crater.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.PHYTOCHEM.2017.11.004
Abstract: Compartmentation of C
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 07-2014
Publisher: Elsevier BV
Date: 12-2017
Publisher: Wiley
Date: 06-03-2019
DOI: 10.1111/GBI.12338
Abstract: Subsurface microbial communities are generally thought to be structured through in situ environmental conditions such as the availability of electron acceptors and donors and porosity, but recent studies suggest that the vertical distribution of a subset of subseafloor microbial taxa, which were present at the time of deposition, were selected by the paleodepositional environment. However, additional highly resolved temporal records of subsurface microbiomes and paired paleoenvironmental reconstructions are needed to justify this claim. Here, we performed a highly resolved shotgun metagenomics survey to study the taxonomic and functional ersity of the subsurface microbiome in Holocene sediments underlying the permanently stratified and anoxic Black Sea. Obligate aerobic bacteria made the largest contribution to the observed shifts in microbial communities associated with known Holocene climate stages and transitions. This suggests that the aerobic fraction of the subseafloor microbiome was seeded from the water column and did not undergo post-depositional selection. In contrast, obligate and facultative anaerobic bacteria showed the most significant response to the establishment of modern-day environmental conditions 5.2 ka ago that led to a major shift in planktonic communities and in the type of sequestered organic matter available for microbial degradation. No significant shift in the subseafloor microbiome was observed as a result of environmental changes that occurred shortly after the marine reconnection, 9 ka ago. This supports the general view that the marine reconnection was a gradual process. We conclude that a high-resolution analysis of downcore changes in the subseafloor microbiome can provide detailed insights into paleoenvironmental conditions and biogeochemical processes that occurred at the time of deposition.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 09-2018
Publisher: Springer Science and Business Media LLC
Date: 25-07-2018
DOI: 10.1038/S41598-018-29571-8
Abstract: There is growing evidence for bacteria playing a role in the pathogenesis and formation of pigmented gallstones from humans. These studies mainly involved cultivation of gallstone-associated bacteria and 16S rRNA profiling, providing an indirect link between processes involved in gallstone formation by the bacteria in-situ . Here, we provide functional metagenomic evidence of a range of genes involved in bile stress response, biofilm formation, and anaerobic energy metabolism by Gram-negative Klebsiella in pigmented gallstones from a 76-year-old male patient. Klebsiella was also present in one cholesterol-type stone in a 30-year-old female patient who had additional cholesterol gallstones characterised by Gram-positive bacteria. Pigmented stones further revealed a predominance of genes involved in carbohydrate metabolism, whilst cholesterol stones indicated a profile dominanted by protein metabolism possibly reflecting known chemical differences between Gram-negative and Gram-positive biofilm matrices. Archaeal genes were not detected. Complementary carbon and hydrogen isotopic analyses of cholesterol within the patients’ stones revealed homogeneity, suggesting a common diet or cholesterol biosynthesis pathway that has little influence on microbial composition. This pilot study provides a framework to study microbial processes that play a potential role in gallstone formation across markedly different types of stones and patient backgrounds.
Publisher: Elsevier BV
Date: 05-2016
Publisher: Elsevier BV
Date: 02-2017
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 05-2016
Publisher: Wiley
Date: 20-07-2020
DOI: 10.1002/ECE3.6580
Abstract: Food web dynamics are vital in shaping the functional ecology of ecosystems. However, trophic ecology is still in its infancy in groundwater ecosystems due to the cryptic nature of these environments. To unravel trophic interactions between subterranean biota, we applied an interdisciplinary Bayesian mixing model design (multi‐factor BMM) based on the integration of faunal C and N bulk tissue stable isotope data (δ 13 C and δ 15 N) with radiocarbon data (Δ 14 C), and prior information from metagenomic analyses. We further compared outcomes from multi‐factor BMM with a conventional isotope double proxy mixing model (SIA BMM), triple proxy (δ 13 C, δ 15 N, and Δ 14 C, multi‐proxy BMM), and double proxy combined with DNA prior information (SIA + DNA BMM) designs. Three species of subterranean beetles ( Paroster macrosturtensis , Paroster mesosturtensis, and Paroster microsturtensis ) and their main prey items Chiltoniidae hipods (AM1: Scutachiltonia axfordi and AM2: Yilgarniella sturtensis ), cyclopoids and harpacticoids from a calcrete in Western Australia were targeted. Diet estimations from stable isotope only models (SIA BMM) indicated homogeneous patterns with modest preferences for hipods as prey items. Multi‐proxy BMM suggested increased—and species‐specific—predatory pressures on hipods coupled with high rates of scavenging redation on sister species. SIA + DNA BMM showed marked preferences for hipods AM1 and AM2, and reduced interspecific scavenging redation on Paroster species. Multi‐factorial BMM revealed the most precise estimations (lower overall SD and very marginal beetles' interspecific interactions), indicating consistent preferences for hipods AM1 in all the beetles' diets. Incorporation of genetic priors allowed crucial refining of the feeding preferences, while integration of more expensive radiocarbon data as a third proxy (when combined with genetic data) produced more precise outcomes but close dietary reconstruction to that from SIA + DNA BMM. Further multidisciplinary modeling from other groundwater environments will help elucidate the potential behind these designs and bring light to the feeding ecology of one the most vital ecosystems worldwide.
Publisher: Elsevier BV
Date: 12-2013
Publisher: Wiley
Date: 03-10-2016
DOI: 10.1111/PCE.12821
Abstract: The
Publisher: Elsevier BV
Date: 10-2015
Publisher: Wiley
Date: 10-12-2019
DOI: 10.1002/ECO.2150
Publisher: Geological Society of America
Date: 12-12-2017
DOI: 10.1130/G38462.1
Publisher: Elsevier BV
Date: 10-2005
Publisher: Elsevier BV
Date: 06-2006
Publisher: Elsevier BV
Date: 08-2011
Publisher: Elsevier BV
Date: 02-2014
Publisher: Elsevier BV
Date: 05-2011
Publisher: Wiley
Date: 08-01-2021
Publisher: Elsevier BV
Date: 08-2009
Publisher: Cambridge University Press (CUP)
Date: 08-09-2016
DOI: 10.1017/S0025315415000491
Abstract: The biology and ecology of calcarean sponges are not as well understood as they are for demosponges. Here, in order to gain new insights, particularly about symbiotic relationships, the calcarean sponge Leucetta prolifera was s led from south-western Australia and examined for its assumed photosymbionts. Pulse litude modulated fluorometry and extraction of photopigments established that the sponge was photosynthetic. Molecular analysis of the bacterial symbionts via sequencing of the V1–V3 region of the 16S rDNA gene confirmed that between 5 and 22% of all sequences belonged to the phylum Cyanobacteria, depending on the in idual s le, with the most dominant strain aligning with Hormoscilla spongeliae , a widely distributed sponge symbiont. Analysis of fatty acids suggested that the sponge obtains nutrition through photosynthates from its symbionts. The relationship is assumed to be mutualistic, with the sponge receiving dietary support and the cyanobacteria sheltering in the sponge tissues. We list all Calcarea presently known to harbour photosymbionts.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Springer Science and Business Media LLC
Date: 10-08-2008
DOI: 10.1038/NGEO260
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 07-2007
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 11-2022
Publisher: European Association of Geoscientists & Engineers
Date: 2019
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 05-2020
Publisher: Frontiers Media SA
Date: 03-07-2015
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.CHROMA.2011.06.021
Abstract: 18α(H)-, 18β(H)-oleanane and lupane are angiosperm-derived biomarkers that are used as age indicators for the Late Cretaceous onwards when the first proliferation of angiosperms occurred. In addition, the 18α(H)-/18β(H)-oleanane ratio is employed as a thermal maturity parameter of crude oil. However, evidence has shown that accurate quantification of these compounds has been impeded by inadequate chromatographic separation by traditional one-dimensional gas chromatography. In this study, we present the separation of 18α(H)-, 18β(H)-oleanane and lupane with comprehensive two-dimensional gas chromatography (GC×GC). Furthermore, it was observed that 18β(H)-oleanane elutes earlier than 18α(H)-oleanane in second dimension (polarity) which we attribute to steric hindrance effects. Two GC conditions have been developed in order to achieve baseline separation of the triterpenoids of interest in complex mixtures such as sediment extracts and crude oils.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 08-2016
Publisher: Proceedings of the National Academy of Sciences
Date: 09-09-2019
Abstract: Highly expanded Cretaceous–Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP)–International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by m of micrite-rich carbonate deposited over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to form a peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarse-grained suevite, including clasts possibly generated by melt–water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impact-induced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.
Publisher: Elsevier BV
Date: 11-2012
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/FP07064
Abstract: Post-photosynthetic carbon isotope fractionation might alter the isotopic signal imprinted on organic matter (OM) during primary carbon fixation by Rubisco. To characterise the influence of post-photosynthetic processes, we investigated the effect of starch storage and remobilisation on the stable carbon isotope signature (δ13C) of different carbon pools in the Eucalyptus delegatensis R. T. Baker leaf and the potential carbon isotope fractionation associated with phloem transport and respiration. Twig phloem exudate and leaf water-soluble OM showed diel variations in δ13C of up to 2.5 and 2‰, respectively, with 13C enrichment during the night and depletion during the day. D ed diel variation was also evident in bulk lipids of the leaf and in the leaf wax fraction. δ13C of nocturnal phloem exudate OM corresponded with the δ13C of carbon released from starch. There was no change in δ13C of phloem carbon along the trunk. CO2 emitted from trunks and roots was 13C enriched compared with the potential organic substrate, and depleted compared with soil-emitted CO2. The results are consistent with transitory starch accumulation and remobilisation governing the diel rhythm of δ13C in phloem-transported OM and fragmentation fractionation occurring during respiration. When using δ13C of OM or CO2 for assessing ecosystem processes or plant reactions towards environmental constraints, post-photosynthetic discrimination should be considered.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.CHROMA.2016.01.026
Abstract: Maleimides (1H-Pyrrole-2,5-diones) are monopyrrolic pigment derivatives with specific alkyl side chains that can be directly linked to their tetrapyrrole precursors, most notably chlorophylls and bacteriochlorophylls. These compounds can be used as palaeoenvironmental indicators such as algal productivity and redox conditions in ancient and modern aquatic systems. Here, we present a new method using two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS), which enables the rapid analysis of maleimides in complex mixtures and different matrices (e.g. sediments and soils), therefore largely simplifying the previous intricate maleimide purification protocol. This method also reduces the potential for bias associated with partial losses due to low recovery and the high volatility of maleimides. The maleimide distributions and concentrations obtained by GC × GC-ToF-MS were reproducible and in agreement with the previously used purification procedure followed by analysis with traditional gas chromatography-mass spectrometry (GC-MS). The new method also resolved previously unrecognised, partial coelution of some maleimides with unknown compounds by quantification with the m/z 75 fragment ion. Furthermore, the higher sensitivity enabled the detection of previously unrecognised and preliminarily identified maleimides based on their relative retention times. The new, easier, rapid and more sensitive GC×GC-ToF-MS method greatly facilitates the analysis of maleimides in environmental s les to study tetrapyrrole degradation processes and will further the development of maleimides as biomarkers for palaeoenvironmental reconstructions.
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.FOODCHEM.2012.05.036
Abstract: Smoke taint in wines from bushfire smoke exposure has become a concern for wine producers. Smoke taint compounds are primarily derived from pyrolysis of the lignin component of fuels. This work examined the influence of the lignin composition of pyrolysed vegetation on the types of putative smoke taint compounds that accrue in wines. At veraison, Merlot vines were exposed to smoke generated from five vegetation types with differing lignin composition. Smoke was generated under pyrolysis conditions that simulated bushfire temperature profiles. Lignin and smoke composition of each fuel type along with putative smoke taint compounds in wines were determined. The results showed that, regardless of fuel type, the commonly reported guaiacyl lignin derived smoke taint compounds, guaiacol and 4-methylguaiacol, represented about 20% of the total phenols in wines. Quantitatively, syringyl lignin derived compounds dominated the total phenol pools in both free and bound forms. The contributions of p-hydroxyphenyls were generally similar to the guaiacyl sources. A further unexpected outcome of the study was that pine smoke affected wines had significantly elevated levels of syringols compared to the controls although pine fuel and its smoke emission lacked syringyl products.
Publisher: Springer Science and Business Media LLC
Date: 23-10-2017
DOI: 10.1038/S41598-017-13873-4
Abstract: Carbonate concretions are known to contain well-preserved fossils and soft tissues. Recently, biomolecules ( e . g . cholesterol) and molecular fossils (biomarkers) were also discovered in a 380 million-year-old concretion, revealing their importance in exceptional preservation of biosignatures. Here, we used a range of microanalytical techniques, biomarkers and compound specific isotope analyses to report the presence of red and white blood cell-like structures as well as platelet-like structures, collagen and cholesterol in an ichthyosaur bone encapsulated in a carbonate concretion from the Early Jurassic (~182.7 Ma). The red blood cell-like structures are four to five times smaller than those identified in modern organisms. Transmission electron microscopy (TEM) analysis revealed that the red blood cell-like structures are organic in composition. We propose that the small size of the blood cell-like structures results from an evolutionary adaptation to the prolonged low oxygen atmospheric levels prevailing during the 70 Ma when ichthyosaurs thrived. The δ 13 C of the ichthyosaur bone cholesterol indicates that it largely derives from a higher level in the food chain and is consistent with a fish and cephalopod diet. The combined findings above demonstrate that carbonate concretions create isolated environments that promote exceptional preservation of fragile tissues and biomolecules.
Publisher: Public Library of Science (PLoS)
Date: 16-10-2019
Publisher: Elsevier BV
Date: 09-2011
Publisher: Elsevier BV
Date: 08-2015
Publisher: Public Library of Science (PLoS)
Date: 28-08-2020
Publisher: Elsevier BV
Date: 05-2022
No related organisations have been discovered for Kliti Grice.
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