74 research outputs found
Characterization of the aerosol produced by infrared femtosecond laser ablation of polyacrylamide gels for the sensitive inductively coupled plasma mass spectrometry detection of selenoproteins
A 2D high repetition rate femtosecondlaserablation strategy (2-mm wide lane) previously developed for the detection of selenoproteins in gel electrophoresis by inductively coupled plasma mass spectrometry was found to increase signal sensitivity by a factor of 40 compared to conventional nanosecond ablation (0.12-mm wide lane) [G. Ballihaut, F. Claverie, C. PĂ©cheyran, S. Mounicou, R. Grimaud and R. Lobinski, Sensitive Detection of Selenoproteins in Gel Electrophoresis by High Repetition Rate FemtosecondLaserAblation-Inductively Coupled Plasma Mass Spectrometry, Anal. Chem. 79 (2007) 6874â6880]. Such improvement couldn't be explained solely by the difference of amount of material ablated, and then, was attributed to the aerosol properties. In order to validate this hypothesis, the characterization of the aerosolproduced by nanosecond and high repetition rate femtosecondlaserablation of polyacrylamidegels was investigated. Our 2D high repetition rate femtosecondlaserablation strategy of 2-mm wide lane was found to produce aerosols of similar particle size distribution compared to nanosecond laserablation of 0.12-mm wide lane, with 38% mass of particles < 1 ”m. However, at high repetition rate, when the ablated surface was reduced, the particle size distribution was shifted toward thinner particle diameter (up to 77% for a 0.12-mm wide lane at 285 ”m depth). Meanwhile, scanning electron microscopy was employed to visualize the morphology of the aerosol. In the case of larger ablation, the fine particles ejected from the sample were found to form agglomerates due to higher ablation rate and then higher collision probability. Additionally, investigations of the plasma temperature changes during the ablation demonstrated that the introduction of such amount of polyacrylamidegel particles had very limited impact on the ICP source (ÎT~ 25 ± 5 K). This suggests that the cohesion forces between the thin particles composing these large aggregates were weak enough to have negligible impact on the ICPMS detection
Direct determination of trace elements in powdered samples by in-cell isotope dilution femtosecond laser ablation ICPMS
A method has been developed for the direct and simultaneous multielement determination of Cu, Zn, Sn, and Pb in soil and sediment samples using femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICPMS) in combination with isotope dilution mass spectrometry (IDMS). The in-cell isotope dilution fs-LA-ICPMS method proposed in this work was based on the quasi-simultaneous ablation of the natural abundance sample and the isotopically enriched solid spike, which was performed using a high repetition rate laser and a fast scanning beam device in a combined manner. Both the sample preparation procedure and the total analysis time have been drastically reduced, in comparison with previous approaches, since a unique multielement isotopically enriched solid spike was employed to analyze different powdered samples. Numerous experimental parameters were carefully selected (e.g., carrier gas flow rate, inlet diameter of the ablation cell, sample translation speed, scanner speed, etc.) in order to ensure the complete mixing between the sample and the solid spike aerosols. The proposed in-cell fs-LA-ICP-IDMS method was tested for the analysis of two soil (CRM 142R, GBW-07405) and two sediment (PACS-2, IAEA-405) reference materials, and the analysis of Cu, Zn, Sn, and Pb yielded good agreement of usually not more than 10% deviation from the certified values and precisions of less than 15% relative standard deviation. Furthermore, the concentrations were in agreement not only with the certified values but also with those obtained by ICP-IDMS after the microwave-assisted digestion of the solid samples, demonstrating therefore that in-cell fs-LA-ICP-IDMS opens the possibility for accurate and precise determinations of trace elements in powdered samples reducing the total sample preparation time to less than 5 min. Additionally, scanning electron microscope measurements showed that the aerosol generated by in-cell fs-LA-ICP-IDMS predominantly consisted of linear agglomerates of small particles (in the order of few tens of nanometers) and a few large spherical particles with diameters below 225 nm
Proteome changes driven by phosphorus deficiency and recovery in the brown tide-forming alga Aureococcus anophagefferens
© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e28949, doi:10.1371/journal.pone.0028949.Shotgun mass spectrometry was used to detect proteins in the harmful alga, Aureococcus anophagefferens, and monitor their relative abundance across nutrient replete (control), phosphate-deficient (âP) and âP refed with phosphate (P-refed) conditions. Spectral counting techniques identified differentially abundant proteins and demonstrated that under phosphate deficiency, A. anophagefferens increases proteins involved in both inorganic and organic phosphorus (P) scavenging, including a phosphate transporter, 5âČ-nucleotidase, and alkaline phosphatase. Additionally, an increase in abundance of a sulfolipid biosynthesis protein was detected in âP and P-refed conditions. Analysis of the polar membrane lipids showed that cellular concentrations of the sulfolipid sulphoquinovosyldiacylglycerol (SQDG) were nearly two-fold greater in the âP condition versus the control condition, while cellular phospholipids were approximately 8-fold less. Transcript and protein abundances were more tightly coupled for gene products involved in P metabolism compared to those involved in a range of other metabolic functions. Comparison of protein abundances between the âP and P-refed conditions identified differences in the timing of protein degradation and turnover. This suggests that culture studies examining nutrient starvation responses will be valuable in interpreting protein abundance patterns for cellular nutritional status and history in metaproteomic datasets.Research for this work was supported by a National Oceanic and Atmospheric Administration ECOHAB grant (#NA09NOS4780206) and National Science Foundation grant (#OCE-0723667) and a STAR Research Assistance Agreement No. R-83041501-0 awarded by the U.S. Environmental Protection Agency. Further support came from the Woods Hole Coastal Ocean Institute. LLW was supported by a Environmental Protection Agency STAR Fellowship (#FP916901). EMB was supported by a National Science Foundation (NSF) Graduate Research Fellowship (#2007037200) and an Environmental Protection Agency STAR Fellowship (#F6E20324)
Critical revision of GD-MS, LA-ICP-MS and SIMS as inorganic mass spectrometric techniques for direct solid analysis
Selenium biochemistry and its role for human health
Despite its very low level in humans, selenium plays an important and unique role among the (semi)metal trace essential elements because it is the only one for which incorporation into proteins is genetically encoded, as the constitutive part of the 21st amino acid, selenocysteine. Twenty-five selenoproteins have been identified so far in the human proteome. The biological functions of some of them are still unknown, whereas for others there is evidence for a role in antioxidant defence, redox state regulation and a wide variety of specific metabolic pathways. In relation to these functions, the selenoproteins emerged in recent years as possible biomarkers of several diseases such as diabetes and several forms of cancer. Comprehension of the selenium biochemical pathways under normal physiological conditions is therefore an important requisite to elucidate its preventing/therapeutic effect for human diseases. This review summarizes the most recent findings on the biochemistry of active selenium species in humans, and addresses the latest evidence on the link between selenium intake, selenoproteins functionality and beneficial health effects. Primary emphasis is given to the interpretation of biochemical mechanisms rather than epidemiological/observational data. In this context, the review includes the following sections: (1) brief introduction; (2) general nutritional aspects of selenium; (3) global view of selenium metabolic routes; (4) detailed characterization of all human selenoproteins; (5) detailed discussion of the relation between selenoproteins and a variety of human diseases
Détection et identification de sélénoprotéines par électrophorÚse sur gel associée aux spectrométries de masse atomique et moléculaire
Selenium is a trace element known for its necessity in organisms' development and its beneficial roles in human health. Research in the past five years strengthened the idea that these properties are largely due to the synthesis of selenoproteins in living organisms. Classical methods in proteomics are not adapted to identify minor selenoproteins. In this PhD work, more sensitive and more specific methods complementary to proteomics have been developed for their detection and identification. A stable selenized protein standard has been produced to develop these methods. The development of laser ablation - Inductively Coupled Plasma - Mass spectrometry coupling (LA-ICP-MS) lead to the detection of selenoproteins after separation by polyacrylamide gel electrophoresis (PAGE). Conventional device of laser ablation has been used and then improved with a new device using femtoseconde laser with ultrafast scanning for more sensitive detection of selenoproteins in biological samples. Once detected, selenoproteins have been identified by molecular mass spectrometry. For this purpose selenopeptids from enzymatic digestion of selenoproteins have been detected first by nanochromatography coupled to ICP-MS and sequenced then by means of by nanochromatography coupled to electrospray ionisation tandem mass spectrometry (nanoHPLC-ESI-MS/MS). LA-ICP-MS device has been successful for detection of new selenoproteins in Desulfococcus multivorans bacteria. This identification procedure has been validated on two purified selenoproteins thioredoxin reductase and carboxymathylated glutathion peroxidase. This developed methodology will lead to identification of selenoproteins and a better understanding of the physiological role of these molecules in numerous living organisms.Le sĂ©lĂ©nium est un Ă©lĂ©ment trace connu pour son caractĂšre essentiel au dĂ©veloppement de nombreux organismes vivants mais Ă©galement pour ses effets bĂ©nĂ©fiques sur la santĂ© humaine. Les recherches effectuĂ©es ces cinq derniĂšres annĂ©es ont renforcĂ© l'idĂ©e que ces propriĂ©tĂ©s seraient dues Ă la synthĂšse de sĂ©lĂ©noprotĂ©ines chez les ĂȘtres vivants. Les mĂ©thodes classiques d'analyse protĂ©omique ne sont pas adaptĂ©es Ă l'identification ciblĂ©e de ces sĂ©lĂ©noprotĂ©ines trĂšs minoritaires. Les travaux de cette thĂšse ont consistĂ© Ă dĂ©velopper des mĂ©thodes complĂ©mentaires plus spĂ©cifiques et sensibles en vue de leur dĂ©tection et de leur identification. Un Ă©talon protĂ©ique sĂ©lĂ©niĂ© stable a Ă©tĂ© produit pour dĂ©velopper ces mĂ©thodes. Le couplage de l'ablation laser et de la spectromĂ©trie de masse couplĂ©e Ă un plasma induit (LA-ICP-MS) a Ă©tĂ© mis en oeuvre pour la dĂ©tection des sĂ©lĂ©noprotĂ©ines aprĂšs une sĂ©paration par Ă©lectrophorĂšse sur gel de polyacrylamide (PAGE). Le dispositif d'ablation laser conventionnel a ici Ă©tĂ© amĂ©liorĂ© avec un laser femtoseconde Ă balayage trĂšs rapide permettant une dĂ©tection plus sensible des sĂ©lĂ©noprotĂ©ines dans les Ă©chantillons biologiques. Une fois dĂ©tectĂ©es, les sĂ©lĂ©noprotĂ©ines ont Ă©tĂ© identifiĂ©es en spectromĂ©trie de masse molĂ©culaire. Pour cela les sĂ©lĂ©nopeptides issus de la digestion enzymatique des sĂ©lĂ©noprotĂ©ines sont d'abord repĂ©rĂ©s en nanochromatographie couplĂ©e Ă l'ICP-MS puis sĂ©quencĂ©s en nanochromatographie couplĂ©e Ă la spectromĂ©trie de masse en tandem Ă ionisation Ă©lectrospray (nanoHPLC-ESI-MS/MS). La procĂ©dure en LA-ICP-MS dĂ©veloppĂ©e a notamment permis la dĂ©tection de nouvelles sĂ©lĂ©noprotĂ©ines chez la bactĂ©rie Desulfococcus multivorans. La procĂ©dure d'identification a Ă©tĂ© validĂ©e sur deux sĂ©lĂ©noprotĂ©ines purifiĂ©es thiorĂ©doxine rĂ©ductase et glutathione peroxydase carboxymĂ©thylĂ©e. La mĂ©thodologie dĂ©veloppĂ©e contribuera Ă l'identification de nouvelles sĂ©lĂ©noprotĂ©ines pour une meilleure comprĂ©hension des rĂŽles physiologiques de ces molĂ©cules chez de nombreux ĂȘtres vivants
Détection et identification de sélénoprotéines par électrophorÚse sur gel associée aux spectrométries de masse atomique et moléculaire.
Le sĂ©lĂ©nium est un Ă©lĂ©ment trace connu pour son caractĂšre essentiel au dĂ©veloppement de nombreux organismes vivants mais Ă©galement pour ses effets bĂ©nĂ©fiques sur la santĂ© humaine. Les recherches effectuĂ©es ces cinq derniĂšres annĂ©es ont renforcĂ© l idĂ©e que ces propriĂ©tĂ©s seraient dues Ă la synthĂšse de sĂ©lĂ©noprotĂ©ines chez les ĂȘtres vivants. Les mĂ©thodes classiques d analyse protĂ©omique ne sont pas adaptĂ©es Ă l identification ciblĂ©e de ces sĂ©lĂ©noprotĂ©ines trĂšs minoritaires. Les travaux de cette thĂšse ont consistĂ© Ă dĂ©velopper des mĂ©thodes complĂ©mentaires plus spĂ©cifiques et sensibles en vue de leur dĂ©tection et de leur identification. Un Ă©talon protĂ©ique sĂ©lĂ©niĂ© stable a Ă©tĂ© produit pour dĂ©velopper ces mĂ©thodes. Le couplage de l ablation laser et de la spectromĂ©trie de masse couplĂ©e Ă un plasma induit (LA-ICP-MS) a Ă©tĂ© mis en oeuvre pour la dĂ©tection des sĂ©lĂ©noprotĂ©ines aprĂšs une sĂ©paration par Ă©lectrophorĂšse sur gel de polyacrylamide (PAGE). Le dispositif d ablation laser conventionnel a ici Ă©tĂ© amĂ©liorĂ© avec un laser femtoseconde Ă balayage trĂšs rapide permettant une dĂ©tection plus sensible des sĂ©lĂ©noprotĂ©ines dans les Ă©chantillons biologiques. Une fois dĂ©tectĂ©es, les sĂ©lĂ©noprotĂ©ines ont Ă©tĂ© identifiĂ©es en spectromĂ©trie de masse molĂ©culaire. Pour cela les sĂ©lĂ©nopeptides issus de la digestion enzymatique des sĂ©lĂ©noprotĂ©ines sont d abord repĂ©rĂ©s en nanochromatographie couplĂ©e Ă l ICP-MS puis sĂ©quencĂ©s en nanochromatographie couplĂ©e Ă la spectromĂ©trie de masse en tandem Ă ionisation Ă©lectrospray (nanoHPLC-ESI-MS/MS). La procĂ©dure en LA-ICP-MS dĂ©veloppĂ©e a notamment permis la dĂ©tection de nouvelles sĂ©lĂ©noprotĂ©ines chez la bactĂ©rie Desulfococcus multivorans. La procĂ©dure d identification a Ă©tĂ© validĂ©e sur deux sĂ©lĂ©noprotĂ©ines purifiĂ©es thiorĂ©doxine rĂ©ductase et glutathione peroxydase carboxymĂ©thylĂ©e. La mĂ©thodologie dĂ©veloppĂ©e contribuera Ă l identification de nouvelles sĂ©lĂ©noprotĂ©ines pour une meilleure comprĂ©hension des rĂŽles physiologiques de ces molĂ©cules chez de nombreux ĂȘtres vivants.Selenium is a trace element known for its necessity in organisms development and its beneficial roles in human health. Research in the past five years strengthened the idea that these properties are largely due to the synthesis of selenoproteins in living organisms. Classical methods in proteomics are not adapted to identify minor selenoproteins. In this PhD work, more sensitive and more specific methods complementary to proteomics have been developed for their detection and identification. A stable selenized protein standard has been produced to develop these methods. The development of laser ablation - Inductively Coupled Plasma - Mass spectrometry coupling (LA-ICP-MS) lead to the detection of selenoproteins after separation by polyacrylamide gel electrophoresis (PAGE). Conventional device of laser ablation has been used and then improved with a new device using femtoseconde laser with ultrafast scanning for more sensitive detection of selenoproteins in biological samples. Once detected, selenoproteins have been identified by molecular mass spectrometry. For this purpose selenopeptids from enzymatic digestion of selenoproteins have been detected first by nanochromatography coupled to ICP-MS and sequenced then by means of by nanochromatography coupled to electrospray ionisation tandem mass spectrometry (nanoHPLC-ESI-MS/MS). LA-ICP-MS device has been successful for detection of new selenoproteins in Desulfococcus multivorans bacteria. This identification procedure has been validated on two purified selenoproteins thioredoxin reductase and carboxymathylated glutathion peroxidase. This developed methodology will lead to identification of selenoproteins and a better understanding of the physiological role of these molecules in numerous living organisms.PAU-BU Sciences (644452103) / SudocSudocFranceF
Effets d'un apport alimentaire en acide docosahexaenoique (DHA, 22:6N-3) sur la composition lipidique membranaire du cerveau et de la rétine, et sur 2 fonctions neurophysiologiques chez le rat (la neurotransmission dopaminergique corticale et la réponse électrophysiologique de la rétine)
RENNES-Agrocampus-CRD (352382323) / SudocSudocFranceF
Diversité de composition en acides gras et qualité nutritionnelle des huiles végétales et des autres matiÚres grasses alimentaires
20 ref. 11 tables Annexes *INRA Laboratoire Nutrition et sécurité alimentaire Jouy-en-Josas (FRA) Diffusion du document : INRA Laboratoire Nutrition et sécurité alimentaire Jouy-en-Josas (FRA)National audienc
Increasing dietary intake of docosahexaenoic acid affects long-chain polyunsaturated fatty acid composition differently according to the brain area in 2-mo old male rat
International audienc
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