Search for massive resonances in dijet systems containing jets tagged as W or Z boson decays in pp collisions at √s=8 TeV

Peer reviewe

Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs

Constraints are presented on the total width of the recently discovered Higgs boson, GH, using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012, corresponding to integrated luminosities of 5.1fb-1 at a center-of-mass energy vs=7 TeV and 19.7fb-1at vs=8 TeV. A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of GH<22 MeV at a 95% confidence level, which is 5.4 times the expected value in the standard model at the measured mass of mH=125.6 GeV

Transport of sucrose into the vacuole of Vitis vinifera cell suspensions

Poster apresentado no Congresso Nacional Micro-Biotec, em Póvoa de Varzim, 2005.The accumulation of sugar in plant cells seems to be mediated by the combined action of plasma membrane and tonoplast sugar transporters, but much work remains to be done to clarify the route(s) of sugar import and how this transport and storage is regulated. Tonoplast vesicles prepared from suspension cultured cells of Vitis vinifera were used as a model system to study the transport of sucrose into the vacuole. The purity of the tonoplast preparations was checked by the marker enzymes vanadate-sensitive H+-ATPase and H+-PPase. ATP- and PPi-dependent fluorescence quenching of ACMA indicated that these vesicles were capable of building up a pH gradient (∆pH, inside acid). Ca2+-induced dissipation of ∆pH was observed on energized vesicles, as a result of Ca2+/H+ antiport activity. However, H+-dependent sucrose transport did not seem to be involved on sucrose uptake since the disaccharide did not induce ∆pH dissipation. Initial velocities of [U-14C]sucrose measured in the absence of a transmembrane H+ gradient showed a simple Michaelis-Menten kinetics, suggesting the involvement of mediated transport with the following kinetic parameters: Km, 57 mM sucrose; Vmax, 49 nmol sucrose s-1 mg-1 protein. Influx and efflux experiments suggested that the affinity of the transport system for sucrose is similar on both sides of the membrane, and the pair sucrose/[U-14C]sucrose exhibited countertransport. It is proposed that sucrose concentrated in the cytoplasm by the activity of energy-dependent plasma membrane sugar carriers is imported into the vacuole by a facilitated diffusion mechanism.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/23169/2005, SFRH/BD/10689/2002, SFRH/BD/13460/2003, SFRH/PBD/17166/2004

Mannitol accumulation as a mechanism for salt stress tolerance in Olea europaea

Poster apresentado no "Congresso Nacional Micro/Biotec 2005", na Póvoa de Varzim, Portugal, em 2005.Resource allocation is an important and highly integrated process in higher plants involving the transport of photoassimilates from source to sink organs. Mannitol and sucrose are the primary photosynthetic products and the major phloem-translocated carbohydrates in Olea europaea L., an important and widespread crop in the Mediterranean basin. In suspension cultured cells of O. europaea, we have previously identified and characterized a H+-dependent polyol transport system whose activity was correlated with OeMaT1 (Olea europaea Mannitol Transporter) expression. The addition of 100-500 mM NaCl to cultured cells led to an increase of polyol carrier capacity and OeMaT1 transcription, as well as a strong repression of mannitol dehydrogenase activity. To further understand the function of mannitol as a compatible solute, cells of O. europaea were grown in sucrose and mannitol as the sole carbon and energy source in the absence and presence of NaCl. Results showed that mannitol was preferred over sucrose, the following values for specific growth rates obtained in the absence of salt: 0.180 d-1 and 0.076 d-1, respectively. Cells grown in the presence of up to 200 mM NaCl exhibited a marked decrease in specific growth rate along with a drastic increase of intracellular Na+ concentration. Cell viability, as assessed by fluorescein diacetate and propidium iodide, decreased along with the increase of NaCl concentration in the culture medium. Furthermore, the addition of 500 mM NaCl showed that mannitol-grown cells remained viable 24h after the salt pulse; sucrose-grown cells were not able to display green fluorescence after the same treatment, and exhibited extensive loss of cell viability as evaluated by the red fluorescence. These results suggest that mannitol behaves as an important osmolyte in O. europaea, showing an enhanced intracellular accumulation and thus compensating for the decrease of external water activity.Fundação para a Ciência e a Tecnologia (FCT)

Evasion of MAIT cell recognition by the African Salmonella Typhimurium ST313 pathovar that causes invasive disease

Mucosal-associated invariant T (MAIT) cells are innate T lymphocytes activated by bacteria that produce vitamin B2 metabolites. Mouse models of infection have demonstrated a role for MAIT cells in antimicrobial defense. However, proposed protective roles of MAIT cells in human infections remain unproven and clinical conditions associated with selective absence of MAIT cells have not been identified. We report that typhoidal and nontyphoidal Salmonella enterica strains activate MAIT cells. However, S. Typhimurium sequence type 313 (ST313) lineage 2 strains, which are responsible for the burden of multidrug-resistant nontyphoidal invasive disease in Africa, escape MAIT cell recognition through overexpression of ribB. This bacterial gene encodes the 4-dihydroxy-2-butanone-4-phosphate synthase enzyme of the riboflavin biosynthetic pathway. The MAIT cell-specific phenotype did not extend to other innate lymphocytes. We propose that ribB overexpression is an evolved trait that facilitates evasion from immune recognition by MAIT cells and contributes to the invasive pathogenesis of S. Typhimurium ST313 lineage 2