Publications by authors named "Ian D Bull"

23 Publications

  • Page 1 of 1

Determination of the δ H values of high molecular weight lipids by high-temperature gas chromatography coupled to isotope ratio mass spectrometry.

Rapid Commun Mass Spectrom 2021 Feb;35(4):e8983

Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.

Rationale: The hydrogen isotopic composition of lipids (δ H ) is widely used in food science and as a proxy for past hydrological conditions. Determining the δ H values of large, well-preserved triacylglycerides and other microbial lipids, such as glycerol dialkyl glycerol tetraether (GDGT) lipids, is thus of widespread interest but has so far not been possible due to their low volatility which prohibits analysis by traditional gas chromatography/pyrolysis/isotope ratio mass spectrometry (GC/P/IRMS).

Methods: We determined the δ H values of large, polar molecules and applied high-temperature gas chromatography (HTGC) methods on a modified GC/P/IRMS system. The system used a high-temperature 7-m GC column, and a glass Y-splitter for low thermal mass. Methods were validated using authentic standards of large, functionalised molecules (triacylglycerides, TGs), purified standards of GDGTs. The results were compared with δ H values determined by high-temperature elemental analyser/pyrolysis/isotope ratio mass spectrometry (HTEA/P/IRMS), and subsequently applied to the analysis of GDGTs in a sample from a methane seep and a Welsh peat.

Results: The δ H values of TGs agreed within error between HTGC/P/IRMS and HTEA/IRMS, with HTGC/P/IRMS showing larger errors. Archaeal lipid GDGTs with up to three cyclisations could be analysed: the δ H values were not significantly different between methods with standard deviations of 5 to 6 ‰. When environmental samples were analysed, the δ H values of isoGDGTs were 50 ‰ more negative than those of terrestrial brGDGTs.

Conclusions: Our results indicate that the HTGC/P/IRMS method developed here is appropriate to determine the δ H values of TGs, GDGTs with up to two cyclisations, and potentially other high molecular weight compounds. The methodology will widen the current analytical window for biomarker and food light stable isotope analyses. Moreover, our initial measurements suggest that bacterial and archaeal GDGT δ H values can record environmental and ecological conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8983DOI Listing
February 2021

Pre-Clovis occupation of the Americas identified by human fecal biomarkers in coprolites from Paisley Caves, Oregon.

Sci Adv 2020 Jul 15;6(29):eaba6404. Epub 2020 Jul 15.

Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.

When and how people first settled in the Americas is an ongoing area of research and debate. The earliest sites typically only contain lithic artifacts that cannot be directly dated. The lack of human skeletal remains in these early contexts means that alternative sources of evidence are needed. Coprolites, and the DNA contained within them, are one such source, but unresolved issues concerning ancient DNA taphonomy and potential for contamination make this approach problematic. Here, we use fecal lipid biomarkers to demonstrate unequivocally that three coprolites dated to pre-Clovis are human, raise questions over the reliance on DNA methods, and present a new radiocarbon date on basketry further supporting pre-Clovis human occupation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/sciadv.aba6404DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363456PMC
July 2020

Intestinal parasites at the Late Bronze Age settlement of Must Farm, in the fens of East Anglia, UK (9th century B.C.E.).

Parasitology 2019 10 8;146(12):1583-1594. Epub 2019 Aug 8.

Department of Archaeology, University of Cambridge, Henry Wellcome Building, Cambridge, CB2 1QH, UK.

Little is known about the types of intestinal parasites that infected people living in prehistoric Britain. The Late Bronze Age archaeological site of Must Farm was a pile-dwelling settlement located in a wetland, consisting of stilted timber structures constructed over a slow-moving freshwater channel. At excavation, sediment samples were collected from occupation deposits around the timber structures. Fifteen coprolites were also hand-recovered from the occupation deposits; four were identified as human and seven as canine, using fecal lipid biomarkers. Digital light microscopy was used to identify preserved helminth eggs in the sediment and coprolites. Eggs of fish tapeworm (Diphyllobothrium latum and Diphyllobothrium dendriticum), Echinostoma sp., giant kidney worm (Dioctophyma renale), probable pig whipworm (Trichuris suis) and Capillaria sp. were found. This is the earliest evidence for fish tapeworm, Echinostoma worm, Capillaria worm and the giant kidney worm so far identified in Britain. It appears that the wetland environment of the settlement contributed to establishing parasite diversity and put the inhabitants at risk of infection by helminth species spread by eating raw fish, frogs or molluscs that flourish in freshwater aquatic environments, conversely the wetland may also have protected them from infection by certain geohelminths.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1017/S0031182019001021DOI Listing
October 2019

Cretaceous dinosaur bone contains recent organic material and provides an environment conducive to microbial communities.

Elife 2019 06 18;8. Epub 2019 Jun 18.

Department of Geosciences, Princeton University, Princeton, United States.

Fossils were thought to lack original organic molecules, but chemical analyses show that some can survive. Dinosaur bone has been proposed to preserve collagen, osteocytes, and blood vessels. However, proteins and labile lipids are diagenetically unstable, and bone is a porous open system, allowing microbial/molecular flux. These 'soft tissues' have been reinterpreted as biofilms. Organic preservation versus contamination of dinosaur bone was examined by freshly excavating, with aseptic protocols, fossils and sedimentary matrix, and chemically/biologically analyzing them. Fossil 'soft tissues' differed from collagen chemically and structurally; while degradation would be expected, the patterns observed did not support this. 16S rRNA amplicon sequencing revealed that dinosaur bone hosted an abundant microbial community different from lesser abundant communities of surrounding sediment. Subsurface dinosaur bone is a relatively fertile habitat, attracting microbes that likely utilize inorganic nutrients and complicate identification of original organic material. There exists potential post-burial taphonomic roles for subsurface microorganisms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.46205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6581507PMC
June 2019

Lipid profiling and analytical discrimination of seven cereals using high temperature gas chromatography coupled to high resolution quadrupole time-of-flight mass spectrometry.

Food Chem 2019 Jun 3;282:27-35. Epub 2019 Jan 3.

Department of Anthropology and Archaeology, University of Bristol, Bristol BS8 1UU, United Kingdom.

Minor lipids in cereals (such as phytosterols and alkylresorcinols) can be important for human nutrition and/or be used as biomarkers for cereal intake. However, the analysis of cereal lipids is very challenging due to the complex lipidome comprising several hundred individual compounds present over a wide range of concentrations. Here we present a method for the profiling of cereal lipids using high temperature gas chromatography coupled to high resolution mass spectrometry (GC/Q-TOF MS). The method was used to investigate the lipid profiles of 77 samples of bread wheat, spelt, einkorn, emmer, barley, rye and oats. Distinct differences in the patterns of alkylresorcinols, free and conjugated sterols and tocopherols between the cereals could be observed. Furthermore, traces of tocomonoenols and diunsaturated and methyl-alkylresorcinols (not previously reported in cereals) could be detected. Finally, the lipid patterns in the cereals could be used to separate the cereals by Principal Component Analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.foodchem.2018.12.109DOI Listing
June 2019

Saccharomyces cerevisiae Atf1p is an alcohol acetyltransferase and a thioesterase in vitro.

Yeast 2017 06 6;34(6):239-251. Epub 2017 Mar 6.

School of Biochemistry, University of Bristol, Bristol, UK.

The alcohol-O-acyltransferases are bisubstrate enzymes that catalyse the transfer of acyl chains from an acyl-coenzyme A (CoA) donor to an acceptor alcohol. In the industrial yeast Saccharomyces cerevisiae this reaction produces acyl esters that are an important influence on the flavour of fermented beverages and foods. There is also a growing interest in using acyltransferases to produce bulk quantities of acyl esters in engineered microbial cell factories. However, the structure and function of the alcohol-O-acyltransferases remain only partly understood. Here, we recombinantly express, purify and characterize Atf1p, the major alcohol acetyltransferase from S. cerevisiae. We find that Atf1p is promiscuous with regard to the alcohol cosubstrate but that the acyltransfer activity is specific for acetyl-CoA. Additionally, we find that Atf1p is an efficient thioesterase in vitro with specificity towards medium-chain-length acyl-CoAs. Unexpectedly, we also find that mutating the supposed catalytic histidine (H191) within the conserved HXXXDG active site motif only moderately reduces the thioesterase activity of Atf1p. Our results imply a role for Atf1p in CoA homeostasis and suggest that engineering Atf1p to reduce the thioesterase activity could improve product yields of acetate esters from cellular factories. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/yea.3229DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5484351PMC
June 2017

Fossilization of melanosomes via sulfurization.

Palaeontology 2016 May 1;59(3):337-350. Epub 2016 Apr 1.

UCD School of Earth Sciences University College Dublin Belfield Dublin 4 Ireland.

Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur-bearing compounds in fossil melanosomes are difficult to resolve. This has implications for interpretations of original colour in fossils based on potential sulfur-rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py-GCMS), fourier transform infrared spectroscopy (FTIR) and time of flight secondary ion mass spectrometry (ToF-SIMS) to assess the mode of preservation of fossil microstructures, confirmed as melanosomes based on the presence of melanin, preserved in frogs from the Late Miocene Libros biota (NE Spain). Our results reveal a high abundance of organosulfur compounds and non-sulfurized fatty acid methyl esters in both the fossil tissues and host sediment; chemical signatures in the fossil tissues are inconsistent with preservation of phaeomelanin. Our results reflect preservation via the diagenetic incorporation of sulfur, i.e. sulfurization (natural vulcanization), and other polymerization processes. Organosulfur compounds and/or elevated concentrations of sulfur have been reported from melanosomes preserved in various invertebrate and vertebrate fossils and depositional settings, suggesting that preservation through sulfurization is likely to be widespread. Future studies of sulfur-rich fossil melanosomes require that the geochemistry of the host sediment is tested for evidence of sulfurization in order to constrain interpretations of potential phaeomelanosomes and thus of original integumentary colour in fossils.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/pala.12238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4957269PMC
May 2016

Morphological and biomolecular evidence for tuberculosis in 8th century AD skeletons from Bélmegyer-Csömöki domb, Hungary.

Tuberculosis (Edinb) 2015 Jun 13;95 Suppl 1:S35-41. Epub 2015 Feb 13.

Department of Biological Anthropology, University of Szeged, Szeged, Hungary. Electronic address:

Macromorphological analysis of skeletons, from 20 selected graves of the 8th century AD Bélmegyer-Csömöki domb, revealed 19 cases of possible skeletal tuberculosis. Biomolecular analyses provided general support for such diagnoses, including the individual without pathology, but the data did not show coherent consistency over the range of biomarkers examined. Amplification of ancient DNA fragments found evidence for the Mycobacterium tuberculosis complex DNA only in five graves. In contrast, varying degrees of lipid biomarker presence were recorded in all except two of the skeletons, though most lipid components appeared to be somewhat degraded. Mycobacterial mycolic acid biomarkers were absent in five cases, but the weak, possibly degraded profiles for the remainder were smaller and inconclusive for either tuberculosis or leprosy. The most positive lipid biomarker evidence for tuberculosis was provided by mycolipenic acid, with 13 clear cases, supported by five distinct possible cases. Combinations of mycocerosic acids were present in all but three graves, but in one case a tuberculosis-leprosy co-infection was indicated. In two specimens with pathology, no lipid biomarker evidence was recorded, but one of these specimens provided M. tuberculosis complex DNA fragments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.tube.2015.02.032DOI Listing
June 2015

7000 year-old tuberculosis cases from Hungary - Osteological and biomolecular evidence.

Tuberculosis (Edinb) 2015 Jun 12;95 Suppl 1:S13-7. Epub 2015 Feb 12.

Department of Biological Anthropology, University of Szeged, Szeged, Hungary. Electronic address:

This study derives from the macroscopic analysis of a Late Neolithic population from Hungary. Remains were recovered from a tell settlement at Hódmezővásárhely-Gorzsa from graves within the settlement as well as pits, ditches, houses and as stray finds. One of the most important discoveries from these remains was evidence of tuberculosis. Pathological analysis of the seventy-one individuals revealed numerous cases of infections and non-specific stress indicators on juveniles and adults, metabolic diseases on juveniles, and evidence of trauma and mechanical changes on adults. Several cases showed potential signs of tuberculosis and further analyses were undertaken, including biomolecular studies. The five individuals were all very young adults and included a striking case of Hypertrophic Pulmonary Osteopathy (HPO) with rib changes, one case with resorptive lesions on the vertebrae, two cases with hypervascularisation on the vertebrae and periosteal remodelling on the ribs, and one case with abnormal blood vessel impressions and a possible lesion on the endocranial surface of the skull. The initial macroscopic diagnosis of these five cases was confirmed by lipid biomarker analyses, and three of them were corroborated by DNA analysis. At present, these 7000-year-old individuals are among the oldest palaeopathological and palaeomicrobiological cases of tuberculosis worldwide.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.tube.2015.02.007DOI Listing
June 2015

A migration-driven model for the historical spread of leprosy in medieval Eastern and Central Europe.

Infect Genet Evol 2015 Apr 11;31:250-6. Epub 2015 Feb 11.

Centre for Clinical Microbiology, Division of Infection and Immunity, University College London, UK; Department of Anatomy and Anthropology Sackler Medical School, Tel Aviv University, Israel.

Leprosy was rare in Europe during the Roman period, yet its prevalence increased dramatically in medieval times. We examined human remains, with paleopathological lesions indicative of leprosy, dated to the 6th-11th century AD, from Central and Eastern Europe and Byzantine Anatolia. Analysis of ancient DNA and bacterial cell wall lipid biomarkers revealed Mycobacterium leprae in skeletal remains from 6th-8th century Northern Italy, 7th-11th century Hungary, 8th-9th century Austria, the Slavic Greater Moravian Empire of the 9th-10th century and 8th-10th century Byzantine samples from Northern Anatolia. These data were analyzed alongside findings published by others. M. leprae is an obligate human pathogen that has undergone an evolutionary bottleneck followed by clonal expansion. Therefore M. leprae genotypes and sub-genotypes give information about the human populations they have infected and their migration. Although data are limited, genotyping demonstrates that historical M. leprae from Byzantine Anatolia, Eastern and Central Europe resembles modern strains in Asia Minor rather than the recently characterized historical strains from North West Europe. The westward migration of peoples from Central Asia in the first millennium may have introduced different M. leprae strains into medieval Europe and certainly would have facilitated the spread of any existing leprosy. The subsequent decline of M. leprae in Europe may be due to increased host resistance. However, molecular evidence of historical leprosy and tuberculosis co-infections suggests that death from tuberculosis in leprosy patients was also a factor.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.meegid.2015.02.001DOI Listing
April 2015

The yeast enzyme Eht1 is an octanoyl-CoA:ethanol acyltransferase that also functions as a thioesterase.

Yeast 2014 Dec 4;31(12):463-74. Epub 2014 Nov 4.

School of Biochemistry, University of Bristol, UK.

Fatty acid ethyl esters are secondary metabolites that are produced during microbial fermentation, in fruiting plants and in higher organisms during ethanol stress. In particular, volatile medium-chain fatty acid ethyl esters are important flavour compounds that impart desirable fruit aromas to fermented beverages, including beer and wine. The biochemical synthesis of medium-chain fatty acid ethyl esters is poorly understood but likely involves acyl-CoA:ethanol O-acyltransferases. Here, we characterize the enzyme ethanol hexanoyl transferase 1 (Eht1) from the brewer's yeast Saccharomyces cerevisiae. Full-length Eht1 was successfully overexpressed from a recombinant yeast plasmid and purified at the milligram scale after detergent solubilization of sedimenting membranes. Recombinant Eht1 was functional as an acyltransferase and, unexpectedly, was optimally active toward octanoyl-CoA, with k(cat)  = 0.28 ± 0.02/s and K(M)  = 1.9 ± 0.6 μm. Eht1 was also revealed to be active as a thioesterase but was not able to hydrolyse p-nitrophenyl acyl esters, in contrast to the findings of a previous study. Low-resolution structural data and site-directed mutagenesis provide experimental support for a predicted α/β-hydrolase domain featuring a Ser-Asp-His catalytic triad. The S. cerevisiae gene YBR177C/EHT1 should thus be reannotated as coding for an octanoyl-CoA:ethanol acyltransferase that can also function as a thioesterase.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/yea.3046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4282330PMC
December 2014

Osteological and biomolecular evidence of a 7000-year-old case of hypertrophic pulmonary osteopathy secondary to tuberculosis from neolithic hungary.

PLoS One 2013 30;8(10):e78252. Epub 2013 Oct 30.

Archaeology, University of Edinburgh, Edinburgh, Scotland, United Kingdom ; Department of Biological Anthropology, University of Szeged, Szeged, Hungary.

Seventy-one individuals from the late Neolithic population of the 7000-year-old site of Hódmezővásárhely-Gorzsa were examined for their skeletal palaeopathology. This revealed numerous cases of infections and non-specific stress indicators in juveniles and adults, metabolic diseases in juveniles, and evidence of trauma and mechanical changes in adults. Several cases showed potential signs of tuberculosis, particularly the remains of the individual HGO-53. This is an important finding that has significant implications for our understanding of this community. The aim of the present study was to seek biomolecular evidence to confirm this diagnosis. HGO-53 was a young male with a striking case of hypertrophic pulmonary osteopathy (HPO), revealing rib changes and cavitations in the vertebral bodies. The initial macroscopic diagnosis of HPO secondary to tuberculosis was confirmed by analysis of Mycobacterium tuberculosis complex specific cell wall lipid biomarkers and corroborated by ancient DNA (aDNA) analysis. This case is the earliest known classical case of HPO on an adult human skeleton and is one of the oldest palaeopathological and palaeomicrobiological tuberculosis cases to date.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0078252PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3813517PMC
February 2015

Mycobacterium tuberculosis complex lipid virulence factors preserved in the 17,000-year-old skeleton of an extinct bison, Bison antiquus.

PLoS One 2012 30;7(7):e41923. Epub 2012 Jul 30.

School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.

Tracing the evolution of ancient diseases depends on the availability and accessibility of suitable biomarkers in archaeological specimens. DNA is potentially information-rich but it depends on a favourable environment for preservation. In the case of the major mycobacterial pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, robust lipid biomarkers are established as alternatives or complements to DNA analyses. A DNA report, a decade ago, suggested that a 17,000-year-old skeleton of extinct Bison antiquus, from Natural Trap Cave, Wyoming, was the oldest known case of tuberculosis. In the current study, key mycobacterial lipid virulence factor biomarkers were detected in the same two samples from this bison. Fluorescence high-performance liquid chromatography (HPLC) indicated the presence of mycolic acids of the mycobacterial type, but they were degraded and could not be precisely correlated with tuberculosis. However, pristine profiles of C(29), C(30) and C(32) mycocerosates and C(27) mycolipenates, typical of the Mycobacterium tuberculosis complex, were recorded by negative ion chemical ionization gas chromatography mass spectrometry of pentafluorobenzyl ester derivatives. These findings were supported by the detection of C(34) and C(36) phthiocerols, which are usually esterified to the mycocerosates. The existence of Pleistocene tuberculosis in the Americas is confirmed and there are many even older animal bones with well-characterised tuberculous lesions similar to those on the analysed sample. In the absence of any evidence of tuberculosis in human skeletons older than 9,000 years BP, the hypothesis that this disease evolved as a zoonosis, before transfer to humans, is given detailed consideration and discussion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0041923PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408397PMC
April 2013

Isotope effects associated with the preparation and methylation of fatty acids by boron trifluoride in methanol for compound-specific stable hydrogen isotope analysis via gas chromatography/thermal conversion/isotope ratio mass spectrometry.

Rapid Commun Mass Spectrom 2012 May;26(10):1232-40

Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Bristol, UK.

Rationale: Compound-specific stable hydrogen isotope analysis of fatty acids is being used increasingly as a means of deriving information from a diverse range of materials of archaeological, geological and environmental interest. Preparative steps required prior to isotope ratio mass spectrometry (IRMS) analysis have the potential to alter determined δD values and hence must be accounted for if accurate δD values for target compounds are to be obtained.

Methods: Myristic, palmitic, stearic, arachidic and behenic saturated fatty acids were derivatised to their respective fatty acid methyl esters (FAMEs), using 14% (w/v) boron trifluoride in methanol then analysed by gas chromatography/thermal conversion/IRMS (GC/TC/IRMS). FAMEs generated from fatty acid sodium salts of unknown δD values were then used to test a correction factor determined for this method of derivatisation.

Results: Derivatisation was found to alter the hydrogen isotopic composition of FAMEs although this effect was reproducible and can be accounted for. The difference between the mean corrected and mean bulk δD values was always less than 6.7 ‰. Extraction of saturated fatty acids and acyl lipids from samples, subsequent hydrolysis, then separation on a solid-phase extraction cartridge, was found to alter the determined δD values by less than one standard deviation.

Conclusions: Overall, it has been shown that for natural abundance hydrogen isotope determinations, the isolation and derivatisation of extracted fatty acids alters the determined δD values only by a numerical increment comparable with the experimental error. This supports the use of the described analytical protocol as an effective means of determining fatty acid δD values by GC/TC/IRMS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.6188DOI Listing
May 2012

Gas chromatographic mass spectrometric detection of dihydroxy fatty acids preserved in the 'bound' phase of organic residues of archaeological pottery vessels.

Rapid Commun Mass Spectrom 2011 Jul;25(13):1893-8

Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.

A methodology is presented for the determination of dihydroxy fatty acids preserved in the 'bound' phase of organic residues preserved in archaeological potsherds. The method comprises saponification, esterification, silica gel column chromatographic fractionation, and analysis by gas chromatography/mass spectrometry. The electron ionisation mass spectra of the trimethylsilyl ether methyl ester derivatives are characterised by fragment ions arising from cleavage of the bond between the two vicinal trimethylsiloxy groups. Other significant fragment ions are [M-15](+.), [M-31](+.), m/z 147 and ions characteristic of vicinal disubstituted (trimethylsiloxy) TMSO- groups (Δ(7,8), Δ(9,10), Δ(11,12) and Δ(13,14): m/z 304, 332, 360 and 388, respectively). The dihydroxy fatty acids identified in archaeological extracts exhibited carbon numbers ranging from C(16) to C(22) and concentrations varying from 0.05 to 14.05 µg g(-1) . The wide range of dihydroxy fatty acids observed indicates that this approach may be applied confidently in screening archaeological potsherds for the degradation products of monounsaturated fatty acids derived from commodities processed in archaeological pottery vessels.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.5038DOI Listing
July 2011

In situ polar organic chemical integrative sampling (POCIS) of steroidal estrogens in sewage treatment works discharge and river water.

J Environ Monit 2011 May 25;13(5):1427-34. Epub 2011 Mar 25.

Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.

A passive sampler (the polar organic chemical integrative sampler; POCIS) was assessed for its ability to sample natural estrogens (17β-estradiol, E2; estrone, E1 and estriol, E3) and the synthetic estrogen (17α-ethynylestradiol, EE2) in the outlet of a sewage treatment works over several weeks. The performance of the POCIS was investigated and optimised in the laboratory before field deployment with high recoveries (66-99%) were achieved for all estrogens. Moreover, it was shown that POCIS does not exhibit any preferential selectivity towards any of the target compounds. The sampling rates of E1, E2 and E3 were 0.018 ± 0.009, 0.025 ± 0.014 and 0.033 ± 0.019 L d(-1), respectively. Following field deployments of 28 days in the discharge of a sewage works, POCIS was shown to enhance the sensitivity of estrogen detection, especially for E3, and provide time-weighted average (TWA) concentrations of E1, E2 and E3, ranging from undetectable to 12 ng L(-1) upstream of the outflow of a sewage treatment works, 13 to 91 ng L(-1) at the outflow and 8 to 39 ng L(-1) downstream of the outflow. This revealed that E1, E2 and E3 are not completely removed during sewage treatment, with concentrations most likely being maintained by contributions from conjugated estrogen analogues. Grab water samples showed considerable variation in the concentrations of estrogens over a longer period (6 months). The results confirm that POCIS is an effective and non-discriminatory method for the detection of low concentrations of estrogens in the aquatic environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c0em00537aDOI Listing
May 2011

Forest contraction in north equatorial Southeast Asia during the Last Glacial Period.

Proc Natl Acad Sci U S A 2010 Aug 26;107(35):15508-11. Epub 2010 Jul 26.

School of Geography and Geosciences, University of St. Andrews, St. Andrews, Fife KY16 9AL, United Kingdom.

Today, insular Southeast Asia is important for both its remarkably rich biodiversity and globally significant roles in atmospheric and oceanic circulation. Despite the fundamental importance of environmental history for diversity and conservation, there is little primary evidence concerning the nature of vegetation in north equatorial Southeast Asia during the Last Glacial Period (LGP). As a result, even the general distribution of vegetation during the Last Glacial Maximum is debated. Here we show, using the stable carbon isotope composition of ancient cave guano profiles, that there was a substantial forest contraction during the LGP on both peninsular Malaysia and Palawan, while rainforest was maintained in northern Borneo. These results directly support rainforest "refugia" hypotheses and provide evidence that environmental barriers likely reduced genetic mixing between Borneo and Sumatra flora and fauna. Moreover, it sheds light on possible early human dispersal events.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1005507107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2932586PMC
August 2010

Applications of stable isotope ratio mass spectrometry in cattle dung carbon cycling studies.

Rapid Commun Mass Spectrom 2010 Mar;24(5):495-500

Soil Cross Institute Programme, North Wyke Research, Okehampton EX20 2SB, UK.

Understanding the fate of dung carbon (C) in soils is challenging due to the ubiquitous presence of the plant-derived organic matter (OM), the source material from which both dung-derived OM and soil organic matter (SOM) predominantly originate. A better understanding of the fate of specific components of this substantial source of OM, and thereby its contribution to C cycling in terrestrial ecosystems, can only be achieved through the use of labelled dung treatments. In this short review, we consider analytical approaches using bulk and compound-specific stable carbon isotope analysis that have been utilised to explore the fate of dung-derived C in soils. Bulk stable carbon isotope analyses are now used routinely to explore OM matter cycling in soils, and have shown that up to 20% of applied dung C may be incorporated into the surface soil horizons several weeks after application, with up to 8% remaining in the soil profile after one year. However, whole soil delta(13)C values represent the average of a wide range of organic components with varying delta(13)C values and mean residence times in soils. Several stable (13)C isotope ratio mass spectrometric methods have been developed to qualify and quantify different fractions of OM in soils and other complex matrices. In particular, thermogravimetry-differential scanning calorimetry-isotope ratio mass spectrometry (TG-DSC-IRMS) and gas chromatography-combustion-IRMS (GC-C-IRMS) analyses have been applied to determine the incorporation and turnover of polymeric plant cell wall materials from C(4) dung into C(3) grassland soils using natural abundance (13)C isotope labelling. Both approaches showed that fluxes of C derived from polysaccharides, i.e. as cellulose or monosaccharide components, were more similar to the behaviour of bulk dung C in soil than lignin. However, lignin and its 4-hydroxypropanoid monomers were unexpectedly dynamic in soil. These findings provide further evidence for emerging themes in biogeochemical investigations of soil OM dynamics that challenge perceived concepts of recalcitrance of C pools in soils, which may have profound implications for the assessment of the potential of agricultural soils to influence terrestrial C sinks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.4332DOI Listing
March 2010

Identification of a disinterred grave by molecular and stable isotope analysis.

Sci Justice 2009 Jun;49(2):142-9

Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.

Confirmation of a potential disinterred grave was sought by GC and GC/MS analyses of lipid extracts of whole soils and white particulate matter. Fatty acid profiles and concentrations determined for three of the soils correlated with the deposition of a large amount of exogenous organic matter, most likely adipocere and/or decomposed body fat. Determination of C16:0 and C18:0 fatty acid delta13C values by GC/C/IRMS revealed the input to be isotopically distinct from common British domesticated animals, plotting closely to values determined for adipose fat obtained from of a murder victim. By considering the difference between delta13C values (delta13C18:0-16:0) a potential isotopic proxy for identifying the source of adipocere (human) and adipose tissue was proposed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scijus.2009.01.016DOI Listing
June 2009

A simple modification of a silicic acid lipid fractionation protocol to eliminate free fatty acids from glycolipid and phospholipid fractions.

J Microbiol Methods 2009 Sep 27;78(3):249-54. Epub 2009 May 27.

Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom.

When fractionating natural and standard lipid mixtures according to the most widely used method for the analysis of soil and other environmental materials, free fatty acids (FFAs) were not recovered quantitatively in the fraction expected to contain all simple lipids. Rather than being eluted from activated silicic acid adsorption chromatographic columns with chloroform, FFAs in standard lipid mixtures appeared only in the two subsequent fractions eluted with acetone and methanol, respectively. Substantial quantities of FFAs from cow dung lipid samples were eluted using chloroform as expected but appreciable amounts also eluted in the acetone (glycolipid) fraction. The fatty acid distribution of the methanol (phospholipid) fraction from dung displayed slightly more FFA compositional character than when FFAs were excluded but this influence was not significant (p=0.08). A simple modification to the silicic acid column technique ensures that FFAs are reproducibly eluted in the chloroform/acetic acid (100:1 v/v; simple lipid) fraction. The modification had no deleterious effect upon the elution characteristics of any phospholipid from a variety of headgroup classes tested. The carry-over of FFAs into glycolipid fractions was confirmed by nanospray ionisation mass spectrometry of the intact polar lipid fractions. As far as could be inferred from the distinctive molecular weight distributions of the glycolipid and phospholipid fractions, none of the complex lipids in dung eluted in both fractions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mimet.2009.05.014DOI Listing
September 2009

13C-Labelling of lipids to investigate microbial communities in the environment.

Curr Opin Biotechnol 2006 Feb 19;17(1):72-82. Epub 2006 Jan 19.

Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.

The introduction of (13)C-labelled substrates to soils, sediments or cultures followed by (13)C analysis of phospholipid fatty acids (PLFAs) provides quantitative and chemotaxonomic information for the groups of microorganisms utilizing a given substrate. Gas chromatography-combustion-isotope ratio mass spectrometry has provided the high precision necessary to measure small isotopic changes (differences in the relative abundances of (13)C to (12)C expressed as delta(13)C values) for nanogram amounts of individual compounds, such as microbial PLFAs. This methodology constitutes a powerful new culture-independent method for investigating microbial communities in the environment. The information obtained is highly complementary to that obtained from gene-probe-based methods, and considerable possibilities exist to extend this methodology to include other biochemical components of microorganisms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.copbio.2006.01.003DOI Listing
February 2006

Lipid content and carbon assimilation in Collembola: implications for the use of compound-specific carbon isotope analysis in animal dietary studies.

Oecologia 2004 May 3;139(3):325-35. Epub 2004 Mar 3.

Organic Geochemistry Unit, Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.

In an effort to understand the relationships between both the lipid content and delta13C values of Collembola and their diet, isotopically labelled (C3 and C4) bakers' yeasts were cultured and fed to two Collembolan species, Folsomia candida and Proisotoma minuta. The fatty acid composition of Collembola generally reflected that of the diet with the addition of the polyunsaturated components 18:2(n-6), 20:4(n-6) and 20:5(n-3), which appeared to be biosynthesised by the Collembola. Whilst ergosterol was the only sterol detected in the yeast diets, only cholesterol was detected in Collembola, and although the delta13C values of diet and consumer sterols differed by >2 per thousand, the delta13C values indicated that cholesterol was derived entirely from dietary sterol. The bulk delta13C values of Collembola were similar to those of the diets, but fatty acid delta13C values did not necessarily reflect those of the dietary fatty acids, indicating significant de novo biosynthesis of fatty acids within Collembola. Switching the Collembola from C3 to C4 yeast enabled the determination of the rates of incorporation of dietary carbon into Collembolan lipids, and showed that half-lives of the incorporation of dietary carbon varied between 1.5 and 5.8 days at 20 degrees C. Cholesterol exhibited the slowest rate of incorporation in both species, while bulk carbon in F. candida possessed an intermediate rate. These results demonstrate that an understanding of the sources of isotopic fractionation and the role of biochemistry in regulating the delta13C values of individual compounds is important in the application of compound-specific isotopic analysis to the study of animal trophic activities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00442-003-1422-1DOI Listing
May 2004

The origin of faeces by means of biomarker detection.

Environ Int 2002 Mar;27(8):647-54

Biogeochemistry Research Centre, School Chemistry, University of Bristol, Cantock's Close, UK.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0160-4120(01)00124-6DOI Listing
March 2002