Optimisation de l'herméticité du détecteur DELPHI pour la recherche de particules supersymétriques à LEP2

In new particles searches at LEP, for the ones characterised by missing energy, it is very important to have the best hermeticity in detecting particles in final states. Photon counters were installed during 1994 and 1995 to cover the weak region in photon detection, between the central part and the end-caps of DELPHI. We discuss the working principles and the tests done on the counters. The optimisation of the counters and of the detectors already present in the other weak regions of DELPHI was examined. We estimate that the efficiency of detecting photons over all the useful solid angle changes from 97\% to more than 99.6\%. This was verified using the 1994 leptonic data of LEP at 95\% confidence level. A search for the lightest supersymmetric partners of the charged bosons (charginos) was done at LEP1.5. All the hermeticity detectors were used to reduce at minimum the contamination from radiative backgrounds. The theoretical motivations and the phenome\-nological de\-scription of the chargiNO1are given. The search was done on the data collected at LEP in November 1995 at 130.4 and 136.3 GeV. We put different lower limits on the chargino mass which depend on the parameters of the theoretical model. They vary between 56.3~GeV and 66.8 GeV. One chargiNO1candidate was found in the data, that is compatible with the prediction from background estimation

Search for charginos, neutralinos, and gravitinos at LEP

The hep-ex data base was decided not to be an appropriate place to make DELPHI notes public. Sorry for the inconvenience.Comment: the paper should not have been made publi

A general protease digestion procedure for optimal protein sequence coverage and PTM analysis of recombinant glycoproteins: Application to the characterization of hLOXL2 glycosylation

Using recombinant DNA technology for expression of protein therapeutics is a maturing field of pharmaceutical research and development. As recombinant proteins are increasingly utilized as biotherapeutics, improved methodologies ensuring the characterization of post-translational modifications (PTMs) are needed. Typically, proteins prepared for PTM analysis are proteolytically digested and analyzed by mass spectrometry. To assure full coverage of the PTMs on a given protein, one must obtain complete sequence coverage of the protein, which is often quite challenging. The objective of the research described here is to design a protocol that maximizes protein sequence coverage and enables detection of post-translational modifications, specifically N-linked glycosylation. To achieve this objective, a highly efficient proteolytic digest protocol using trypsin was designed by comparing the relative merits of denaturing agents (urea and Rapigest™ SF), reducing agents (dithiothreitol, DTT, and tris(2-carboxyethyl)phophine, TCEP), and various concentrations of alkylating agent (iodoacetamide, IAM). After analysis of human apo-transferrin using various protease digestion protocols, ideal conditions were determined to contain 6 M urea for denaturation, 5 mM TCEP for reduction, 10 mM IAM for alkylation, and 10 mM DTT, to quench excess IAM before the addition of trypsin. This method was successfully applied to a novel recombinant protein, human lysyl oxidase-like 2 (hLOXL2). Furthermore, the glycosylation PTMs were readily detected at two glycosylation sites in the protein. These digestion conditions were specifically designed for PTM analysis of recombinant proteins and biotherapeutics, and the work described herein fills an unmet need in the growing field of biopharmaceutical analysis

GlycoPep Grader: A web-based utility for assigning the composition of N-linked glycopeptides

GlycoPep Grader (GPG) is a freely-available software tool designed to accelerate the process of accurately determining glycopeptide composition from tandem mass spectrometric data. GPG relies on the identification of unique dissociation patterns shown for high mannose, hybrid, and complex N-linked glycoprotein types, including patterns specific to those structures containing fucose or sialic acid residues. The novel GPG scoring algorithm scores potential candidate compositions of the same nominal mass against MS/MS data through evaluation of the Y1 ion and other peptide-containing product ions, across multiple charge states, when applicable. In addition to evaluating the peptide portions of a given glycopeptide, the GPG algorithm predicts and scores product ions that result from unique neutral losses of terminal glycans. GPG has been applied to a variety of glycoproteins, including RNase B, asialofetuin and transferrin, and the HIV envelope glycoprotein, CON-S gp140 CFI. The GPG software is implemented predominantly in PostgreSQL, with PHP as the presentation tier, and is publically accessible online. Thus far, the algorithm has identified the correct compositional assignment from multiple candidate N-glycopeptides in all tests performed

The species identification problem in mirids (Hemiptera: Heteroptera) highlighted by DNA barcoding and species delimitation studies

Due to the difficulties associated with detecting and correctly identifying mirids, developing an accurate species identification approach is crucial, especially for potential harmful species. Accurate identification is often hampered by inadequate morphological key characters, invalid and/or outdated systematics, and biases in the molecular data available in public databases. This study aimed to verify whether molecular characterization (i.e. DNA barcoding) is able to identify mirid species of economic relevance and if species delimitation approaches are reliable tools for species discrimination. Cytochrome c oxydase 1 (cox1) data from public genetic databases were compared with new data obtained from mirids sampled in different Italian localities, including an old specimen from private collection, showing contrasting results. Based on the DNA barcoding approach, for the genus Orthops, all sequences were unambiguously assigned to the same species, while in Adelphocoris, Lygus and Trigonotylus there were over-descriptions and/or misidentifications of species. On the other hand, in Polymerus and Deraeocoris there was an underestimation of the taxonomic diversity. The present study highlighted an important methodological problem: DNA barcoding can be a good tool for pest identification and discrimination, but the taxonomic unreliability of public DNA databases can make this method useless or even misleading

Effects of the equilibrium atmosphere on Taleggio cheese storage in micro perforated packaging

Taleggio is an Italian smear-ripened cheese, whose complex microbiota demands the optimisation of the packaging system to avoid excessive changes during storage. Metabolic processes of the cheese rind microbiota can be usefully exploited in equilibrium modified atmosphere packaging (EMAP) by balancing microbiota respiration and film permeation. Here, we present the application of three different micro perforated EMAPs as models for smear-ripened cheese compared to two control packaging configurations. Analyses of the main microbial groups, headspace gas, textural profile, and sensory properties were performed to find the best packaging for storage. Results showed that two of the alternative micro perforated packaging systems were able to control the excessive changes during storage, thus limiting fungal overgrowth and allowing the typical development of smear microbiota with minor changes to hardness and cohesiveness. Finally, the sensory evaluation positively favoured one of the alternatively packed cheeses based on its compactness, typical dairy traits, and minor off-flavours. These findings showed that EMAP can be a valid alternative solution to control the storage of Taleggio cheese. Further studies could be conducted to evaluate this system on other smear cheeses

Identification of novel loci for the generation of reporter mice

Deciphering the etiology of complex pathologies at molecular level requires longitudinal studies encompassing multiple biochemical pathways (apoptosis, proliferation, inflammation, oxidative stress). In vivo imaging of current reporter animals enabled the spatio-temporal analysis of specific molecular events, however, the lack of a multiplicity of loci for the generalized and regulated expression of the integrated transgenes hampers the creation of systems for the simultaneous analysis of more than a biochemical pathways at the time. We here developed and tested an in vivo-based methodology for the identification of multiple insertional loci suitable for the generation of reliable reporter mice. The validity of the methodology was tested with the generation of novel mice useful to report on inflammation and oxidative stress

Asymmetric correlation matrices: an analysis of financial data

We analyze the spectral properties of correlation matrices between distinct statistical systems. Such matrices are intrinsically non symmetric, and lend themselves to extend the spectral analyses usually performed on standard Pearson correlation matrices to the realm of complex eigenvalues. We employ some recent random matrix theory results on the average eigenvalue density of this type of matrices to distinguish between noise and non trivial correlation structures, and we focus on financial data as a case study. Namely, we employ daily prices of stocks belonging to the American and British stock exchanges, and look for the emergence of correlations between two such markets in the eigenvalue spectrum of their non symmetric correlation matrix. We find several non trivial results, also when considering time-lagged correlations over short lags, and we corroborate our findings by additionally studying the asymmetric correlation matrix of the principal components of our datasets.Comment: Revised version; 11 pages, 13 figure