14 research outputs found

    Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

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    A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

    Identification and mRNA Expression of Heat Shock Proteins in the Mud Crab (Scylla paramamosain) in Response to Acute Nitrite Exposure

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    Heat shock proteins (HSPs) play an important role in protecting organisms against various stressors. Heat shock protein 40 (HSP40) is a class of the heat shock protein family and performs a function as co-chaperone of HSP70. In this study, an HSP40 gene from the mud crab Scylla paramamosain (SpHSP40) was identified and characterized. The full-length cDNA of SpHSP40 was 1904 bp, containing an open reading frame (ORF) of 1191 bp, a 5´UTR of 118 bp, and a 3´UTR of 595 bp. The deduced amino acid sequence of SpHSP40 contained all four classical HSP40 family signatures. Quantitative real-time PCR analysis revealed that SpHSP40 transcript was expressed in a wide range of tissues, while strong expression was observed in the hepatopancreas. In order to understand the response of heat shock proteins induced by nitrite exposure, expression levels of HSPs (SpHSP90, SpHSP70, SpHSP60 and SpHSP40) mRNA in the hepatopancreas and gills were investigated. Results show that HSPs (SpHSP90, SpHSP70, SpHSP60 and SpHSP40) were up-regulated displaying a time-dependent pattern in response to nitrite stress. All these results indicate that HSPs play an important role in mediating environmental stress in mud crabs

    Identification and mRNA Expression of Antioxidant Enzyme Genes in the Mud Crab (Scylla paramamosain) in Response to Acute Ammonia and Nitrite Exposure

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    Thioredoxin reductase (TrxR) is a conserved protein that is involved in protecting organisms against various oxidative stresses. In this study, a thioredoxin reductase gene was cloned from the mud crab Scylla paramamosain (SpTrxR). The full-length cDNA of SpTrxR is comprised of 2724 bp with a 1791 bp open reading frame that encodes a putative protein of 596 amino acids. The deduced amino acid sequence of SpTrxR contains the typical TrxR domain. Quantitative real-time PCR analysis revealed that the SpTrxR mRNA was distributed abundantly in mud crabs, while strong expression was observed mainly in the gills. The expression of antioxidant enzyme genes (SpTrxR, SpTrx, SpSOD, and SpCAT) was measured using quantitative real-time PCR after acute ammonia and nitrite exposure. The results show that antioxidant enzyme genes (SpTrxR, SpTrx, SpSOD, and SpCAT) were modulated by acute ammonia and nitrite exposure. These results suggest that antioxidant enzyme genes play an important role in protecting organisms against oxidative stres
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