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- Abramowski, A., et al.
(författare)
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The 2010 very high energy gamma-RAY flare and 10 years of multi-wavelength observations of M 87
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 746:2, s. 151-
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Tidskriftsartikel (refereegranskat)abstract
- The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3-6) x 10(9) M-circle dot) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz Very Long Baseline Array, VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times of tau(rise)(d) = (1.69 +/- 0.30) days and tau(decay)(d) = (0.611 +/- 0.080) days, respectively. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (similar to day), peak fluxes (Phi(>0.35 TeV) similar or equal to (1-3) x 10(-11) photons cm(-2) s(-1)), and VHE spectra. VLBA radio observations of 43 GHz of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken similar to 3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core (flux increased by factor similar to 2; variability timescale <2 days). The long-term (2001-2010) multi-wavelength (MWL) light curve of M 87, spanning from radio to VHE and including data from Hubble Space Telescope, Liverpool Telescope, Very Large Array, and European VLBI Network, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified. In the outer kiloparsec jet region, in particular in HST-1, no enhanced MWL activity was detected in 2008 and 2010, disfavoring it as the origin of the VHE flares during these years. Shortly after two of the three flares (2008 and 2010), the X-ray core was observed to be at a higher flux level than its characteristic range (determined from more than 60 monitoring observations: 2002-2009). In 2005, the strong flux dominance of HST-1 could have suppressed the detection of such a feature. Published models for VHE gamma-ray emission from M 87 are reviewed in the light of the new data.
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- Leymarie, N., et al.
(författare)
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Interlaboratory Study on Differential Analysis of Protein Glycosylation by Mass Spectrometry: The ABRF Glycoprotein Research Multi-Institutional Study 2012
- 2013
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Ingår i: Molecular & Cellular Proteomics. - 1535-9476. ; 12:10, s. 2935-2951
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Tidskriftsartikel (refereegranskat)abstract
- One of the principal goals of glycoprotein research is to correlate glycan structure and function. Such correlation is necessary in order for one to understand the mechanisms whereby glycoprotein structure elaborates the functions of myriad proteins. The accurate comparison of glycoforms and quantification of glycosites are essential steps in this direction. Mass spectrometry has emerged as a powerful analytical technique in the field of glycoprotein characterization. Its sensitivity, high dynamic range, and mass accuracy provide both quantitative and sequence/structural information. As part of the 2012 ABRF Glycoprotein Research Group study, we explored the use of mass spectrometry and ancillary methodologies to characterize the glycoforms of two sources of human prostate specific antigen (PSA). PSA is used as a tumor marker for prostate cancer, with increasing blood levels used to distinguish between normal and cancer states. The glycans on PSA are believed to be biantennary N-linked, and it has been observed that prostate cancer tissues and cell lines contain more antennae than their benign counterparts. Thus, the ability to quantify differences in glycosylation associated with cancer has the potential to positively impact the use of PSA as a biomarker. We studied standard peptide-based proteomics/glycomics methodologies, including LC-MS/MS for peptide/glycopeptide sequencing and label-free approaches for differential quantification. We performed an interlaboratory study to determine the ability of different laboratories to correctly characterize the differences between glycoforms from two different sources using mass spectrometry methods. We used clustering analysis and ancillary statistical data treatment on the data sets submitted by participating laboratories to obtain a consensus of the glycoforms and abundances. The results demonstrate the relative strengths and weaknesses of top-down glycoproteomics, bottom-up glycoproteomics, and glycomics methods. T6G 2G2, Canada. [Cipollo, John F.; An, Yanming] US FDA, Ctr Biol Evaluat & Res, Bethesda, MD 20993 USA. [Desaire, Heather; Go, Eden P.] Univ Kansas, Lawrence, KS 66045 USA. [Goldman, Radoslav; Pompach, Petr; Sanda, Miloslav] Georgetown Univ, Dept Oncol, Washington, DC [Halim, Adnan; Larson, Goran; Nilsson, Jonas] Univ Gothenburg, Sahlgrenska Acad, Dept Clin Chem & [Hensbergen, Paul J.; Wuhrer, Manfred] Leiden Univ, Med Ctr, Biomol Mass Spectrometry Unit, NL- [Jabs, Wolfgang; Marx, Kristina; Resemann, Anja; Schweiger-Hufnagel, Ulrike; Suckau, Detlev] Bruker [Ly, Mellisa; Staples, Gregory O.] Agilent Technol, Agilent Labs, Santa Clara, CA 95051 USA. [Mechref, Yehia; Song, Ehwang] Texas Tech Univ, Dept Chem & Biochem, Lubbock, TX 79409 USA. [Nyalwidhe, Julius O.; Watson, Megan] Eastern Virginia Med Sch, Leroy T Canoles Jr Canc Res Ctr, Dept [Packer, Nicolle H.; Thaysen-Andersen, Morten] Macquarie Univ, Dept Chem & Biomol Sci, Biomol [Sihlbom, Carina] Gothenburg Univ, Prote Core Facil, Gothenburg, Sweden. [Tang, Haixu] Indiana Univ, Sch Informat, Bloomington, IN 47405 USA. [Valmuv, Leena] Finnish Red Cross Blood Serv, Helsinki 00310, Finland. [Wada, Yoshinao] Osaka Med Ctr Maternal & Child Hlth, Res Inst, Izumi Ku, Osaka 5941101, Japan.
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- Fouquier d'Hérouel, Aymeric, et al.
(författare)
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A simple and efficient method to search for selected primary transcripts : non-coding and antisense RNAs in the human pathogen Enterococcus faecalis
- 2011
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 39:7, s. E46-
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Tidskriftsartikel (refereegranskat)abstract
- Enterococcus faecalis is a commensal bacterium and a major opportunistic human pathogen. In this study, we combined in silico predictions with a novel 5'RACE-derivative method coined '5'tagRACE', to perform the first search for non-coding RNAs (ncRNAs) encoded on the E. faecalis chromosome. We used the 5'tagRACE to simultaneously probe and characterize primary transcripts, and demonstrate here the simplicity, the reliability and the sensitivity of the method. The 5'tagRACE is complementary to tiling arrays or RNA-sequencing methods, and is also directly applicable to deep RNA sequencing and should significantly improve functional studies of bacterial RNA landscapes. From 45 selected loci of the E. faecalis chromosome, we discovered and mapped 29 novel ncRNAs, 10 putative novel mRNAs and 16 antisense transcriptional organizations. We describe in more detail the oxygen-dependent expression of one ncRNA located in an E. faecalis pathogenicity island, the existence of an ncRNA that is antisense to the ncRNA modulator of the RNA polymerase, SsrS and provide evidences for the functional interplay between two distinct toxin-antitoxin modules.
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