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Ronald P Kiene - One of the best experts on this subject based on the ideXlab platform.
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Dimethylsulfide production in sargasso sea eddies
Deep-sea Research Part Ii-topical Studies in Oceanography, 2008Co-Authors: K E Bailey, Ronald P Kiene, Dierdre A Toole, Byron Blomquist, Raymond G Najjar, B J Huebert, David J Kieber, Patricia A Matrai, G R Westby, Daniela A. Del ValleAbstract:Abstract Lagrangian time series of Dimethylsulfide (DMS) concentrations from a cyclonic and an anticyclonic eddy in the Sargasso Sea were used in conjunction with measured DMS loss rates and a model of vertical mixing to estimate gross DMS production in the upper 60 m during summer 2004. Loss terms included biological consumption, photolysis, and ventilation to the atmosphere. The time- and depth (0–60 m)-averaged gross DMS production was estimated to be 0.73±0.09 nM d −1 in the cyclonic eddy and 0.90±0.15 nM d −1 in the anticyclonic eddy, with respective DMS replacement times of 5±1 and 6±1 d. The higher estimated rate of gross production and lower measured loss rate constants in the anticyclonic eddy were equally responsible for this eddy's 50% higher DMS inventory (0–60 m). When normalized to chlorophyll and total dimethylsulfoniopropionate (DMSP), estimated gross production in the anticyclonic eddy was about twice that in the cyclonic eddy, consistent with the greater fraction of phytoplankton that were DMSP producers in the anticyclonic eddy. Higher rates of gross production were estimated below the mixed layer, contributing to the subsurface DMS maximum found in both eddies. In both eddies, gas exchange, microbial consumption, and photolysis were roughly equal DMS loss terms in the surface mixed layer (0.2–0.4 nM d −1 ). Vertical mixing was a substantial source of DMS to the surface mixed layer in both eddies (0.2–0.3 nM d −1 ) owing to the relatively high DMS concentrations below the mixed layer. Estimated net biological DMS production rates (gross production minus microbial consumption) in the mixed layer were substantially lower (by almost a factor of 3) than those estimated in a previous study of the Sargasso Sea, which may explain the relatively low mixed-layer DMS concentrations found here during July 2004 (∼3 nM) compared to previous summers (∼4–6 nM).
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Phylogenetic identification and metabolism of marine Dimethylsulfide-consuming bacteria.
Environmental microbiology, 2006Co-Authors: Maria Vila-costa, Ronald P Kiene, Daniela A. Del Valle, José M. González, Doris Slezak, Olga Sánchez, Rafel SimóAbstract:Summary Microbial consumption is one of the main processes, along with photolysis and ventilation, that remove the biogenic trace gas Dimethylsulfide (DMS) from the surface ocean. Although a few isolates of marine bacteria have been studied for their ability to utilize DMS, little is known about the characteristics or phylogenetic affiliation of DMS consumers in seawater. We enriched coastal and open-ocean waters with different carbon sources to stimulate different bacterial communities (glucose-consuming bacteria, methyl group-consuming bacteria and DMS consumers) in order to test how this affected DMS consumption and to examine which organisms might be involved. Dimethylsulfide consumption was greatly stimulated in the DMS addition treatments whereas there was no stimulation in the other treatments. Analysis of microbial DNA by two different techniques (sequenced bands from DGGE gels and clone libraries) showed that bacteria grown specifically with the presence of DMS were closely related to the genus Methylophaga. We also followed the fate of consumed DMS in some of the enrichments. Dimethylsulfide was converted mostly to DMSO in glucose or methanol enrichments, whereas it was converted mostly to sulfate in DMS enrichments, the latter suggesting use of DMS as a carbon and energy source. Our results indicate that unlike the biochemical precursor of DMS, dimethylsulfoniopropionate (DMSP), which is consumed by a broad spectrum of marine microorganisms, DMS seems to be utilized as a carbon and electron source by specialists. This is consistent with the usual observation that DMSP turns over at much higher rates than DMS.
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Thiol methylation potential in anoxic, low-pH wetland sediments and its relationship with Dimethylsulfide production and organic carbon cycling.
FEMS microbiology ecology, 2004Co-Authors: Edward G. Stets, Mark E. Hines, Ronald P KieneAbstract:Dimethylsulfide (CH3SCH3) is formed in anoxic freshwater sediments by biological methylation of methanethiol (CH3SH). We measured thiol methylation potential in low-pH, Sphagnum peat sediments from Alaska and Alabama by adding ethanethiol (CH3CH2SH) to peat slurries and quantifying the rate of ethylmethylsulfide (CH3CH2SCH3) formation. Thiol methylation potential ranged from 12 to 154 nM h−1 and was significantly related to Dimethylsulfide accumulation rates (P=0.0007; r2=0.48). Addition of methanol or syringic acid stimulated thiol methylation potential and Dimethylsulfide accumulation rate, suggesting that these compounds could be methyl donors. Addition of acetate or its metabolic precursors (glucose or Sphagnum plant material) inhibited thiol methylation potential, but not carbon dioxide or methane production. Inhibition of methanogenesis with either 2-bromoethanesulfonic acid or KNO3 consistently inhibited thiol methylation potential and Dimethylsulfide accumulation. These results suggest that methanogens play a role in thiol methylation and therefore Dimethylsulfide formation.
Rafel Simó - One of the best experts on this subject based on the ideXlab platform.
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Development and validation of a shipboard system for measuring high-resolution vertical profiles of aqueous Dimethylsulfide concentrations using chemical ionisation mass spectrometry
Environmental Chemistry, 2014Co-Authors: Sarah-jeanne Royer, Eric S. Saltzman, Martí Galí, Cyril A. Mccormick, Thomas G. Bell, Rafel SimóAbstract:Environmental context Dimethylsulfide, a trace gas produced by oceanic plankton, is a key chemical species in the global cycles of sulfur and aerosols, with implications that span marine ecology to climate regulation. Knowledge of what governs Dimethylsulfide production in the surface ocean depends on our ability to measure concentration changes over time and depth. We describe a sampling and analytical system that provides continuous shipboard measurements of Dimethylsulfide concentrations in high-resolution vertical profiles. Abstract A sampling and analytical system has been developed for shipboard measurements of high-resolution vertical profiles of the marine trace gas Dimethylsulfide (DMS). The system consists of a tube attached to a conductivity–temperature–depth (CTD) probe with a peristaltic pump on deck that delivers seawater to a membrane equilibrator and atmospheric pressure chemical ionisation mass spectrometer (Eq-APCIMS). This allows profiling of DMS concentrations to a depth of 50m, with a depth resolution of 1.3–2m and a detection limit of nearly 0.1nmolL–1. The seawater is also plumbed to allow parallel operation of additional continuous instruments, and simultaneous collection of discrete samples for complementary analyses. A valve alternates delivery of seawater from the vertical profiler and the ship’s underway intake, thereby providing high-resolution measurements in both the vertical and horizontal dimensions. Tests conducted on various cruises in the Mediterranean Sea, Atlantic, Indian, and Pacific Oceans show good agreement between the Eq-APCIMS measurements and purge and trap gas chromatography with flame photometric detection (GC-FPD) and demonstrate that the delivery of seawater from the underway pump did not significantly affect endogenous DMS concentrations. Combining the continuous flow DMS analysis with high-frequency hydrographic, optical, biological and meteorological measurements will greatly improve the spatial–temporal resolution of seagoing measurements and improve our understanding of DMS cycling.
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Phylogenetic identification and metabolism of marine Dimethylsulfide-consuming bacteria.
Environmental microbiology, 2006Co-Authors: Maria Vila-costa, Ronald P Kiene, Daniela A. Del Valle, José M. González, Doris Slezak, Olga Sánchez, Rafel SimóAbstract:Summary Microbial consumption is one of the main processes, along with photolysis and ventilation, that remove the biogenic trace gas Dimethylsulfide (DMS) from the surface ocean. Although a few isolates of marine bacteria have been studied for their ability to utilize DMS, little is known about the characteristics or phylogenetic affiliation of DMS consumers in seawater. We enriched coastal and open-ocean waters with different carbon sources to stimulate different bacterial communities (glucose-consuming bacteria, methyl group-consuming bacteria and DMS consumers) in order to test how this affected DMS consumption and to examine which organisms might be involved. Dimethylsulfide consumption was greatly stimulated in the DMS addition treatments whereas there was no stimulation in the other treatments. Analysis of microbial DNA by two different techniques (sequenced bands from DGGE gels and clone libraries) showed that bacteria grown specifically with the presence of DMS were closely related to the genus Methylophaga. We also followed the fate of consumed DMS in some of the enrichments. Dimethylsulfide was converted mostly to DMSO in glucose or methanol enrichments, whereas it was converted mostly to sulfate in DMS enrichments, the latter suggesting use of DMS as a carbon and energy source. Our results indicate that unlike the biochemical precursor of DMS, dimethylsulfoniopropionate (DMSP), which is consumed by a broad spectrum of marine microorganisms, DMS seems to be utilized as a carbon and electron source by specialists. This is consistent with the usual observation that DMSP turns over at much higher rates than DMS.
Eric S. Saltzman - One of the best experts on this subject based on the ideXlab platform.
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Development and validation of a shipboard system for measuring high-resolution vertical profiles of aqueous Dimethylsulfide concentrations using chemical ionisation mass spectrometry
Environmental Chemistry, 2014Co-Authors: Sarah-jeanne Royer, Eric S. Saltzman, Martí Galí, Cyril A. Mccormick, Thomas G. Bell, Rafel SimóAbstract:Environmental context Dimethylsulfide, a trace gas produced by oceanic plankton, is a key chemical species in the global cycles of sulfur and aerosols, with implications that span marine ecology to climate regulation. Knowledge of what governs Dimethylsulfide production in the surface ocean depends on our ability to measure concentration changes over time and depth. We describe a sampling and analytical system that provides continuous shipboard measurements of Dimethylsulfide concentrations in high-resolution vertical profiles. Abstract A sampling and analytical system has been developed for shipboard measurements of high-resolution vertical profiles of the marine trace gas Dimethylsulfide (DMS). The system consists of a tube attached to a conductivity–temperature–depth (CTD) probe with a peristaltic pump on deck that delivers seawater to a membrane equilibrator and atmospheric pressure chemical ionisation mass spectrometer (Eq-APCIMS). This allows profiling of DMS concentrations to a depth of 50m, with a depth resolution of 1.3–2m and a detection limit of nearly 0.1nmolL–1. The seawater is also plumbed to allow parallel operation of additional continuous instruments, and simultaneous collection of discrete samples for complementary analyses. A valve alternates delivery of seawater from the vertical profiler and the ship’s underway intake, thereby providing high-resolution measurements in both the vertical and horizontal dimensions. Tests conducted on various cruises in the Mediterranean Sea, Atlantic, Indian, and Pacific Oceans show good agreement between the Eq-APCIMS measurements and purge and trap gas chromatography with flame photometric detection (GC-FPD) and demonstrate that the delivery of seawater from the underway pump did not significantly affect endogenous DMS concentrations. Combining the continuous flow DMS analysis with high-frequency hydrographic, optical, biological and meteorological measurements will greatly improve the spatial–temporal resolution of seagoing measurements and improve our understanding of DMS cycling.
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Correction to “Eddy correlation measurements of the air/sea flux of Dimethylsulfide over the North Pacific Ocean”
Journal of Geophysical Research, 2008Co-Authors: Christa Marandino, W. J. De Bruyn, Scott D. Miller, Eric S. SaltzmanAbstract:[1] In the paper ‘‘Eddy correlation measurements of the air/sea flux of Dimethylsulfide over the North Pacific Ocean’’ by C. A. Marandino et al. (Journal of Geophysical Research, 112, D03301, doi:10.1029/2006JD007293, 2007), the Wanninkhof [1992] parameterization in Figure 13 was calculated incorrectly. The revised Figure 13 is included. The discussion and conclusions of the original paper are not impacted by this change.
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Shipboard measurements of dimethyl sulfide and SO2 southwest of Tasmania during the First Aerosol Characterization Experiment (ACE 1)
Journal of Geophysical Research: Atmospheres, 1998Co-Authors: Warren J. De Bruyn, Timothy S. Bates, Jill M Cainey, Eric S. SaltzmanAbstract:Measurements of seawater Dimethylsulfide (DMS), atmospheric Dimethylsulfide, and sulfur dioxide (SO 2 ) were made on board the R/VDiscoverer in the Southern Ocean, southeast of Australia, as part of the First Aerosol Characterization Experiment (ACE 1). The measurements covered a latitude range of 40°S–55°S during November-December 1995. Seawater DMS concentrations ranged from 0.4 to 6.8 nM, with a mean of 1.7±1.1 nM (1σ). The highest DMS concentrations were found in subtropical convergence zone waters north of 44°S, and the lowest were found in polar waters south of 49°S. In general, seawater DMS concentrations increased during the course of the study, presumably due to the onset of austral spring warming. Atmospheric DMS concentrations ranged from 24 to 350 parts per trillion by volume (pptv), with a mean of 112±61 pptv (1σ). Atmospheric SO2 was predominantly of marine origin with occasional anthropogenic input, as evidenced by correlation with elevated 222 Rn and air mass trajectories. Concentrations ranged from 3 to 1000 pptv with a mean of 48.8± 49 pptv (1σ) and a median 15.8 pptv. The mean SO2 concentration observed in undisturbed marine air was 11.9±7.6 pptv (1σ), and the mean DMS to SO2 ratio in these conditions was 13±9 (1σ). Diurnal variations in
Ralf Riedel - One of the best experts on this subject based on the ideXlab platform.
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synthesis of silyl substituted organoboranes by hydroboration of vinylsilanes
Polyhedron, 2000Co-Authors: Lutz Ruwisch, Peter Durichen, Ralf RiedelAbstract:Hydroboration reactions of dichloroborane-, monochloroborane- and borane-Dimethylsulfide with dichloromethylvinylsilane and trichlorovinylsilane were investigated. The proposed structures of the produced organochlorosilylboranes 1–4 were verified by NMR spectroscopic measurements and in the case of [α-(dichloromethylsilyl)ethyl]dichloroborane-Dimethylsulfide (4) the molecular structure was determined by single-crystal X-ray diffraction (L.M. Ruwisch, R. Riedel, U. Klingebiel, M. Noltemeyer, Z. Naturforsch., Teil B 54 (1999) 624). Following the Markovnikov rule, the first addition appears strictly regioselective in the α-position to silicon, producing one chiral methine group between silicon and dichloroborane in compound 4. The second addition of borane- or monochloroborane-Dimethylsulfide at the vinyl groups of dichloromethylvinylsilane and trichlorovinylsilane also takes place in the α-position to silicon, forming a second chiral methine group. In the case of borane-Dimethylsulfide the third addition occurs in the β-position (anti-Markovnikov) owing to steric hindrance to boron in tris[(dichloromethylsilyl)ethyl]borane (1). A stepwise substitution of chlorine bonded at boron in compounds 2 and 3 using hexamethyldisilazane produces bis[α-(dichloromethylsilyl)ethyl]boryl-trimethylsilylamine (5) and bis[α-(trichlorosilyl)ethyl]boryl-trimethylsilylamine (6), respectively, under release of chlorotrimethylsilane. The remaining trimethylsilylamine group in 6 can be replaced by further reaction with 3 forming tetrakis[α-(trichlorosilyl)ethyl]diborylamine (7). This reaction resembles a selective amino condensation at boron. In a similar condensation reaction of 4 with equivalent amounts of hexamethyldisilazane, tris[α-(dichloromethylsilyl)ethyl]borazine (8) can be obtained.
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Synthese und Molekülstruktur des [α-(Dichlormethylsilyl)ethyl]- dichlorboran-dimethylsulfid / Synthesis and Molecular Structure of [α-(Dichloromethylsilyl)ethyl]- dichloroborane-Dimethylsulfide
Zeitschrift für Naturforschung B, 1999Co-Authors: Lutz Ruwisch, Ralf Riedel, Uwe Klingebiel, Mathias NoltemeyerAbstract:[α-(Dichloromethylsilyl)ethyl]-dichloroborane-Dimethylsulfide has been synthesized by the reaction of dichloromethylvinylsilane with dichloroborane-Dimethylsulfide and its molecular structure determined by single crystal X-ray diffraction and by spectroscopic methods. Following the Markovnikov rule, a chiral methine group is formed as a bridge between silicon and boron.
Alastair G Mcewan - One of the best experts on this subject based on the ideXlab platform.
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Dimethylsulfide acceptor oxidoreductase from rhodobacter sulfidophilus the purified enzyme contains b type haem and a pterin molybdenum cofactor
FEBS Journal, 1996Co-Authors: Steven P Hanlon, Tzehsien Toh, Peter S Solomon, Robert A Holt, Alastair G McewanAbstract:Dimethylsulfide:acceptor oxidoreductase was purified from the purple non-sulfur phototrophic bacterium Rhodobacter sulfidophilus. The native form of the enzyme had a molecular mass of 152 kDa and was composed of three distinct subunits of 94, 38 and 32 kDa. Dimethylsulfide:acceptor oxidoreductase did not oxidise other thioethers which were tested. The enzyme was able to reduce a variety of N-oxides using reduced methylviologen as electron donor but it reduced dimethylsulfoxide at a very low rate. The resting form of Dimethylsulfide:acceptor oxidoreductase exhibited a spectrum which was characteristic of a reduced cytochrome with absorbance maxima at 562 nm, 533 nm and 428 nm. Pyridine haemochrome analysis established that the cytochrome contained a b -type haem and a content of 0.65 mol protohaem/mol enzyme was determined. After oxidation of the haem with ferricyanide, the absorbance spectrum of the reduced cytochrome was restored by reduction with Dimethylsulfide. Metal analysis revealed that Dimethylsulfide:acceptor oxidoreductase contained 0.5 mol Mo and 3.5 mol Fe/mol enzyme. Heat treatment of the enzyme released material with fluorescence excitation and emission spectra which were characteristic of form B of the pterin component of the pterin molybdenum cofactor. From this analysis it is concluded that Dimethylsulfide: acceptor oxidoreductase is a molybdenum oxotransferase which may also contain a iron-sulfur cluster. It is suggested that the haem and pterin molybdenum cofactor are associated with the 94-kDa subunit.