The Experts below are selected from a list of 903 Experts worldwide ranked by ideXlab platform
Clare Woulds - One of the best experts on this subject based on the ideXlab platform.
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alteration of organic matter during infaunal polychaete gut passage and links to sediment organic geochemistry part ii fatty acids and Aldoses
Geochimica et Cosmochimica Acta, 2014Co-Authors: Clare Woulds, Jack J Middelburg, Greg CowieAbstract:The activities of sediment-dwelling fauna are known to influence the rates of and pathways through which organic matter is cycled in marine sediments, and thus to influence eventual organic carbon burial or decay. However, due to methodological constraints, the role of faunal gut passage in determining the subsequent composition and thus degradability of organic matter is relatively little studied. Previous studies of organic matter digestion by benthic fauna have been unable to detect uptake and retention of specific biochemicals in faunal tissues, and have been of durations too short to fit digestion into the context of longer-term sedimentary degradation processes. Therefore this study aimed to investigate the aldose and fatty acid compositional alterations occurring to organic matter during gut passage by the abundant and ubiquitous polychaetes Hediste diversicolor and Arenicola marina, and to link these to longer-term changes typically observed during organic matter decay. This aim was approached through microcosm experiments in which selected polychaetes were fed with 13 C-labelled algal detritus, and organisms, sediments, and faecal pellets were sampled at three timepoints over � 6 weeks. Samples were analysed for their 13 C-labelled aldose and fatty acid contents using GC–MS and GC–IRMS. Compound-selective net accumulation of biochemicals in polychaete tissues was observed for both Aldoses and fatty acids, and the patterns of this were taxon-specific. The dominant patterns included an overall loss of glucose and polyunsaturated fatty acids; and preferential preservation or production of arabinose, microbial compounds (rhamnose, fucose and microbial fatty acids), and animal-synthesised fatty acids. These patterns may have been driven by fatty acid essentiality, preferential metabolism of glucose, and A. marina grazing on bacteria. Fatty acid suites in sediments from faunated microcosms showed greater proportions of saturated fatty acids and bacterial markers than those from afaunal controls. Aldose suite alterations were similar in faunated microcosms and afaunal controls, however the impact of faunal gut passage on sedimentary aldose compositions may be observable over longer timescales. Therefore this study provides direct evidence that polychaete gut passage influences OM composition both through taxonspecific selective assimilation and retention in polychaete tissues, and also through interactions with the microbial community. 2014 Published by Elsevier Ltd.
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a method for the quantitative detection of 13c labelled amino acids and Aldoses in marine sediments and fauna
Organic Geochemistry, 2010Co-Authors: Clare Woulds, Greg Cowie, Jack J MiddelburgAbstract:Abstract Recent experimental studies of the processing of organic matter in marine sediments by benthic fauna have used isotopically labelled organic substrates as tracers for natural organic matter and have followed processes such as ingestion, bioturbation, remineralisation and burial. In order to use these labelling techniques to trace organic matter on a detailed level through the process of digestion and assimilation, it is necessary to be able to detect isotopically labelled biochemicals and to distinguish them from their natural, unlabelled counterparts. In this study existing methods for the GC analysis of amino acids and Aldoses are combined with the Sun-type isotope calibration technique for GC–MS (Sun M.Y., 2000, Org. Geochem. 31, 199–209) to achieve quantitative measurement of 13 C labelled amino acids and Aldoses in fauna and sediment samples from a feeding experiment. In order to demonstrate the methods, example data from feeding experiments are presented, which suggest that assimilation of amino acids and Aldoses by polychaetes during digestion is selective and taxon specific.
Greg Cowie - One of the best experts on this subject based on the ideXlab platform.
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alteration of organic matter during infaunal polychaete gut passage and links to sediment organic geochemistry part ii fatty acids and Aldoses
Geochimica et Cosmochimica Acta, 2014Co-Authors: Clare Woulds, Jack J Middelburg, Greg CowieAbstract:The activities of sediment-dwelling fauna are known to influence the rates of and pathways through which organic matter is cycled in marine sediments, and thus to influence eventual organic carbon burial or decay. However, due to methodological constraints, the role of faunal gut passage in determining the subsequent composition and thus degradability of organic matter is relatively little studied. Previous studies of organic matter digestion by benthic fauna have been unable to detect uptake and retention of specific biochemicals in faunal tissues, and have been of durations too short to fit digestion into the context of longer-term sedimentary degradation processes. Therefore this study aimed to investigate the aldose and fatty acid compositional alterations occurring to organic matter during gut passage by the abundant and ubiquitous polychaetes Hediste diversicolor and Arenicola marina, and to link these to longer-term changes typically observed during organic matter decay. This aim was approached through microcosm experiments in which selected polychaetes were fed with 13 C-labelled algal detritus, and organisms, sediments, and faecal pellets were sampled at three timepoints over � 6 weeks. Samples were analysed for their 13 C-labelled aldose and fatty acid contents using GC–MS and GC–IRMS. Compound-selective net accumulation of biochemicals in polychaete tissues was observed for both Aldoses and fatty acids, and the patterns of this were taxon-specific. The dominant patterns included an overall loss of glucose and polyunsaturated fatty acids; and preferential preservation or production of arabinose, microbial compounds (rhamnose, fucose and microbial fatty acids), and animal-synthesised fatty acids. These patterns may have been driven by fatty acid essentiality, preferential metabolism of glucose, and A. marina grazing on bacteria. Fatty acid suites in sediments from faunated microcosms showed greater proportions of saturated fatty acids and bacterial markers than those from afaunal controls. Aldose suite alterations were similar in faunated microcosms and afaunal controls, however the impact of faunal gut passage on sedimentary aldose compositions may be observable over longer timescales. Therefore this study provides direct evidence that polychaete gut passage influences OM composition both through taxonspecific selective assimilation and retention in polychaete tissues, and also through interactions with the microbial community. 2014 Published by Elsevier Ltd.
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a method for the quantitative detection of 13c labelled amino acids and Aldoses in marine sediments and fauna
Organic Geochemistry, 2010Co-Authors: Clare Woulds, Greg Cowie, Jack J MiddelburgAbstract:Abstract Recent experimental studies of the processing of organic matter in marine sediments by benthic fauna have used isotopically labelled organic substrates as tracers for natural organic matter and have followed processes such as ingestion, bioturbation, remineralisation and burial. In order to use these labelling techniques to trace organic matter on a detailed level through the process of digestion and assimilation, it is necessary to be able to detect isotopically labelled biochemicals and to distinguish them from their natural, unlabelled counterparts. In this study existing methods for the GC analysis of amino acids and Aldoses are combined with the Sun-type isotope calibration technique for GC–MS (Sun M.Y., 2000, Org. Geochem. 31, 199–209) to achieve quantitative measurement of 13 C labelled amino acids and Aldoses in fauna and sediment samples from a feeding experiment. In order to demonstrate the methods, example data from feeding experiments are presented, which suggest that assimilation of amino acids and Aldoses by polychaetes during digestion is selective and taxon specific.
Jeff Sands - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Aldose Reductase, Sorbitol Dehydrogenase, and Taurine Cotransporter mRNA in Rat Medulla
Journal of the American Society of Nephrology, 1995Co-Authors: Sonia Martial, S Price, Jeff SandsAbstract:The regulation of mRNA for aldose reductase, sorbitol dehydrogenase, and the Na+/Cl-/taurine cotransporter was studied with three in vivo models in which urinary concentration is reduced: Sprague-Dawley rats undergoing a water diuresis or fed a low-protein diet or Brattleboro rats. In Sprague-Dawley rats, 3 days of water diuresis reduced inner medullary aldose reductase mRNA abundance 6.5-fold compared with untreated rats, whereas sorbitol dehydrogenase and taurine cotransporter mRNA were unchanged. When water diuretic rats were acutely deprived of water, urine osmolality increased significantly after 4 h but aldose reductase mRNA did not increase until 12 h. Heat shock protein-70 mRNA was not increased by water deprivation. Second, in rats fed a low-protein diet for 3 wk, aldose reductase mRNA increased two-fold, whereas sorbitol dehydrogenase and taurine cotransporter mRNA were unchanged. Finally, in Brattleboro rats, urine osmolality and levels of aldose reductase and taurine cotransporter mRNA increased in response to 1 day of water deprivation, whereas sorbitol dehydrogenase mRNA was unchanged. Administering vasopressin (1 U/day) to Brattleboro rats for 8 days also increased urine osmolality and aldose reductase mRNA but did not alter sorbitol dehydrogenase or taurine cotransporter mRNA. This result is consistent with the hypothesis that changes in urine osmolality induce changes in aldose reductase mRNA abundance that are independent of vasopressin. It was concluded that, in rat inner medulla: (1) aldose reductase mRNA abundance varies with changes in water balance or dietary protein, whereas sorbitol dehydrogenase and taurine cotransporter mRNA do not; and (2) heat shock protein-70 mRNA abundance is not increased during acute osmotic stress.
Niclas G Karlsson - One of the best experts on this subject based on the ideXlab platform.
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negative ion cid fragmentation of o linked oligosaccharide Aldoses charge induced and charge remote fragmentation
Journal of the American Society for Mass Spectrometry, 2011Co-Authors: Roisin A Doohan, Catherine A Hayes, Brendan Harhen, Niclas G KarlssonAbstract:Collision induced dissociation (CID) fragmentation was compared between reducing and reduced sulfated, sialylated, and neutral O-linked oligosaccharides. It was found that fragmentation of the [M – H]– ions of Aldoses with acidic residues gave unique Z-fragmentation of the reducing end GalNAc containing the acidic C-6 branch, where the entire C-3 branch was lost. This fragmentation pathway, which is not seen in the alditols, showed that the process involved charge remote fragmentation catalyzed by a reducing end acidic anomeric proton. With structures containing sialic acid on both the C-3 and C-6 branch, the [M – H]– ions were dominated by the loss of sialic acid. This fragmentation pathway was also pronounced in the [M – 2H]2– ions revealing both the C-6 Z-fragment plus its complementary C-3 C-fragment in addition to glycosidic and cross ring fragmentation. This generation of the Z/C-fragment pairs from GalNAc showed that the charges were not participating in their generation. Fragmentation of neutral Aldoses showed pronounced Z-fragmentation believed to be generated by proton migration from the C-6 branch to the negatively charged GalNAc residue followed by charge remote fragmentation similar to the acidic oligosaccharides. In addition, A-type fragments generated by charge induced fragmentation of neutral oligosaccharides were observed when the charge migrated from C-1 of the GalNAc to the GlcNAc residue followed by rearrangement to accommodate the 0,2A-fragmentation. LC-MS also showed that O-linked Aldoses existed as interchangeable α/β pyranose anomers, in addition to a third isomer (25% of the total free aldose) believed to be the furanose form.
Jack J Middelburg - One of the best experts on this subject based on the ideXlab platform.
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alteration of organic matter during infaunal polychaete gut passage and links to sediment organic geochemistry part ii fatty acids and Aldoses
Geochimica et Cosmochimica Acta, 2014Co-Authors: Clare Woulds, Jack J Middelburg, Greg CowieAbstract:The activities of sediment-dwelling fauna are known to influence the rates of and pathways through which organic matter is cycled in marine sediments, and thus to influence eventual organic carbon burial or decay. However, due to methodological constraints, the role of faunal gut passage in determining the subsequent composition and thus degradability of organic matter is relatively little studied. Previous studies of organic matter digestion by benthic fauna have been unable to detect uptake and retention of specific biochemicals in faunal tissues, and have been of durations too short to fit digestion into the context of longer-term sedimentary degradation processes. Therefore this study aimed to investigate the aldose and fatty acid compositional alterations occurring to organic matter during gut passage by the abundant and ubiquitous polychaetes Hediste diversicolor and Arenicola marina, and to link these to longer-term changes typically observed during organic matter decay. This aim was approached through microcosm experiments in which selected polychaetes were fed with 13 C-labelled algal detritus, and organisms, sediments, and faecal pellets were sampled at three timepoints over � 6 weeks. Samples were analysed for their 13 C-labelled aldose and fatty acid contents using GC–MS and GC–IRMS. Compound-selective net accumulation of biochemicals in polychaete tissues was observed for both Aldoses and fatty acids, and the patterns of this were taxon-specific. The dominant patterns included an overall loss of glucose and polyunsaturated fatty acids; and preferential preservation or production of arabinose, microbial compounds (rhamnose, fucose and microbial fatty acids), and animal-synthesised fatty acids. These patterns may have been driven by fatty acid essentiality, preferential metabolism of glucose, and A. marina grazing on bacteria. Fatty acid suites in sediments from faunated microcosms showed greater proportions of saturated fatty acids and bacterial markers than those from afaunal controls. Aldose suite alterations were similar in faunated microcosms and afaunal controls, however the impact of faunal gut passage on sedimentary aldose compositions may be observable over longer timescales. Therefore this study provides direct evidence that polychaete gut passage influences OM composition both through taxonspecific selective assimilation and retention in polychaete tissues, and also through interactions with the microbial community. 2014 Published by Elsevier Ltd.
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a method for the quantitative detection of 13c labelled amino acids and Aldoses in marine sediments and fauna
Organic Geochemistry, 2010Co-Authors: Clare Woulds, Greg Cowie, Jack J MiddelburgAbstract:Abstract Recent experimental studies of the processing of organic matter in marine sediments by benthic fauna have used isotopically labelled organic substrates as tracers for natural organic matter and have followed processes such as ingestion, bioturbation, remineralisation and burial. In order to use these labelling techniques to trace organic matter on a detailed level through the process of digestion and assimilation, it is necessary to be able to detect isotopically labelled biochemicals and to distinguish them from their natural, unlabelled counterparts. In this study existing methods for the GC analysis of amino acids and Aldoses are combined with the Sun-type isotope calibration technique for GC–MS (Sun M.Y., 2000, Org. Geochem. 31, 199–209) to achieve quantitative measurement of 13 C labelled amino acids and Aldoses in fauna and sediment samples from a feeding experiment. In order to demonstrate the methods, example data from feeding experiments are presented, which suggest that assimilation of amino acids and Aldoses by polychaetes during digestion is selective and taxon specific.