952 resultados para Neutral Re(I) complexes
Resumo:
In so-called unisexual teleost fishes, a broad spectrum of evolutionaty stages with varying amounts of sexual elements has evolved. These range from pure sperm-dependent parthenogenesis (gynogenesis) without or with different amounts of paternal leakage to hybridogenesis with hemiclonal diploid gametogenesis or genome elimination folowed by meiosis (meiotic hybridogenesis). All of these phenomena are hybrid origin. Many of these fish form complexes which involve the coexistence of one or more sexually reproducing species with derived all-female forms that have various ploidy levels and reproductive modes, including gynogenesis, (meiotic) hybridogenesis nnd sexual reproduction. In teleosts, parthenogenetic reproduction is strictly dependent on sperm to initate embryonic development. As opposed to true parthenogenesis, sperm-dependent parthenogenetic teleost lineages must primarily coexist with their "sperm donor", usually males from a parental sexual lineage or from a related sexual species. In some systems, gynogens were able to escape from their initial sperm donors ("host switch") and therefore, to enlarge their ranges and ecological niches. Sperm donors normally do not contribue genetically to the next generation. However, paternal leakage is observed in many systems contributing differing amounts of genetic material (from microchromosomes to entire chromosome sets) allowing interaction between genomes of different origin. Hybridogenesis is similar to gynogenesis in depending upon coexisence with sexual species but incorporates recombined genetic material by true fertilizazion. While hybridogens usually form clonal gametes, some triploids are capable of genome elimination followed by a normal diploid meiosis. Sperm-dependent parthenogenesis and hybridogenesis combine disadvantages and advantages from both sexuality and asexuality. Here, we give an overview of sperm-dependent breeding complexes in fishes, discuss the evolutionary consequences of paternal leakage, and speculate about the evolutionary significance of intergenomic (re)combination.
Resumo:
La mediació en l‘àmbit penal del menor és un mitjà innovador de resolució de conflictes, que s’ha de promoure per les seves innegables avantatges envers el model de punició tradicional. Permet que tots el agents afectats puguin intervenir i apropa la justícia a la societat, tot donant un paper fonamental a la víctima i afavorint-hi les possibilitats resocialitzadores i educatives del menor infractor. L’objectiu principal ha de ser facilitar al menor, que tot just comença la seva carrera criminal, les eines necessàries per evitar-ne l’evolució com a adult delinqüent, amb el consegüent benefici per a tota la societat. Igualment, la víctima, gran oblidada del procés penal, adquireix un nou protagonisme per decidir l‘abast de la seva reparació i, alhora, la societat reforça els mecanismes per obtenir la pau social. Aquestes finalitats tan loables mereixen l’esforç de les institucions per invertir en mitjans personals i materials que garanteixin l’eficàcia i la viabilitat dels programes de mediació i reparació. L’experiència a Catalunya, comunitat pionera en aquest àmbit, ve avalada per uns resultats excel·lents en el camp de la jurisdicció dels menors, segons reconeixen els mateixos protagonistes. Els resultats favorables de la mediació en l’àmbit del menor han permès, fins i tot, iniciar la primera experiència a l’Estat pel que fa a la mediació en la justícia penal d’adults. S’obren, doncs, noves possibilitats dins la filosofia del dret penal que ens permetran assolir en el futur solucions innovadores, proposades per les persones directament afectades. Aquest ha estat l’objectiu del nostre estudi, tot mirant d’aprofundir els avantatges de la mediació envers al sistema punitiu tradicional i els resultats de la seva implantació a Catalunya, així com cercar solucions que alleugeressin la sempre sobrecarregada Administració de justícia.
Resumo:
Barraclough and co-workers (in a paper published in 1996) observed that there was a significant positive correlation between the rate of evolution of the rbcL chloroplast gene within families of flowering plants and the number of species in those families. We tested three additional data sets of our own (based on both plastid and nuclear genes) and used methods designed specifically for the comparison of sister families (based on random speciation and extinction). We show that, over all sister groups, the correlation between the rate of gene evolution and an increased diversity is not always present. Despite tending towards a positive association, the observation of individual probabilities presents a U-shaped distribution of association (i.e. it can be either significantly positive or negative). We discuss the influence of both phylogenetic sampling and applied taxonomies on the results.
Resumo:
Polarized and G-polarized CR manifolds are smooth manifolds endowed with a double structure: a real foliation &em&F&/em& (given by the action of a Lie group G in the G-polarized case) and a transverse CR distribution. Polarized means that (E,J) is roughly speaking invariant by&em&F&/em&. Both structures are therefore linked up. The interplay between them gives to polarized CR-manifolds a very rich geometry. In this paper, we study the properties of polarized and G-polarized manifolds, putting special emphasis on their deformations.
Resumo:
This article provides an in-depth study of long-term female unemployment in Catalonia.Long-term unemployment statistics reveal which social groups are most likely to experience difficulty re-entering the labour market. In this case, we found that women are mainly affected by this type of labour exclusion, in particular poorly qualified, working-class women who are aged over 45 and with family responsibilities.The article aims to explore how the overlapping of factors such as gender, age, social class, origin and the division of work based on gender are related to long-term female unemployment. Moreover, we were able to detect which conceptual tools provide us with the production/reproduction paradigm so as to be able to analyse the future of female unemployment. The methodology we used combines quantitative and qualitative approaches. On the one hand, the analysis of secondary statistical data focusing on Catalonia is useful in understanding the situation from a macro-social perspective. On the other hand, an exploratory discussion group enables us to investigate social imaginary practises among unemployed working class women aged over 45. This discussion group was held in Igualada -capital of the Anoia region - an area of Catalonia deeply affected by unemployment in the current economic crisis.
Resumo:
Cette thèse, qui se base sur des entretiens qualitatifs, porte sur la négociation des références identitaires de musulmans immigrés et réfugiés en provenance de Γ ex-Yougoslavie au Luxembourg et s'intéresse à la pertinence changeante de la religion dans la conception de soi. Selon une approche constructiviste et interactionniste, l'identité est conçue comme un projet constamment négocié, reconstruit dans des processus d'interaction sociale et en fonction des contextes sociaux. Nos données suggèrent l'émergence de constructions identitaires complexes et attestent de la pluridimensionalité et de l'intersectionnalité des références identitaires utilisées dans la conception de soi et témoignent de la non-réduction des individus à des catégories fixes. Différentes catégories sont rendues significatives et de multiples frontières sont établies afin de se différencier de figures d'altérité changeantes, sélectivement choisies pour construire une certaine image de soi. Les discours identitaires témoignent de l'aspiration à une identité positive, dans une situation caractérisée par la perte du statut social et des stigmatisations multiples, en tant que ex-Yougoslaves, demandeurs d'asile et musulmans. Nos interlocuteurs établissent un répertoire identitaire composé de marqueurs transposés, inventés et revalorisés, leur permettant de reconstruire une identité positive pour soi et leurs audiences. Ce travail décrit les manières dont les individus établissent leur répertoire identitaire à l'aide de marqueurs transposés, inventés et revalorisés, leur permettant de reconstruire une identité positive pour soi et leurs audiences et montre comment les processus de différenciation de 'l'autre' dans le pays d'origine et d'accueil sont reliés. - The question addressed in this project with a qualitative design, is how muslim migrants and refugees from the former Socialist Federal Republic of Yugoslavia in Luxemburg negotiate salient identity references in a new social political environment and discusses the changing significance of religion and the way it is integrated in the identity patchwork. According to a constructivist and interactionist approach, conceiving identity as a constantly negotiated project, reconstructed in interaction and with regard to social context, identities are relevant only in relation to particular other groups and in certain situations of interaction. Our data suggest the emergence of complex identity patterns using multiple references for self- description and attest of the intersectionnality of identity references and show that individuals can't be reduced to fixed categories. Different categories are made salient and multiple symbolic boundaries are established in order to differentiate from different "others", selected in order to construct a certain self-concept. The discourses of our participants attest of an aspiration towards a positive identity in a situation characterized by the loss of social status and multiple stigmata. This thesis describes the ways how individuals establish their identity repertoire with invented, transposed and negotiated identity references, that allow them to construct a favourable identity for themselves and their public and shows how différenciation processes in home and host country are related.
Resumo:
Després d’analitzar el potencial de la muntanya d’Alinyà, s’ha observat que és un lloc idoni per desenvolupar activitats d’educació ambiental (EA). Per aquest motiu s’elabora un itinerari d’EA, part del qual és adaptat sensorialment. Havent analitzat els pros i contres de cada itine-rari ja descrit en la muntanya d’Alinyà s’ha escollit l’itinerari 3 que s’amplia fins a la zona de El Ribatell per aconseguir un dels objectius inicials: l’adaptació d’un itinerari d’EA per a persones amb mobilitat reduïda o discapacita-des. En el disseny de l’itinerari s’han inclòs tots els elements d’interès socio-ambiental més desta-cables de la zona, entre els quals es pot destacar els diferents tipus de boscos, aspectes geològics com el Roc de la Pena o els quatre grans rapi-nyaires que es poden trobar a la zona.
Resumo:
The goal of adoptive T cell therapy in cancer is to provide effective antitumor immunity by transfer of selected populations of tumor Ag-specific T cells. Transfer of T cells with high TCR avidity is critical for in vivo efficacy. In this study, we demonstrate that fluorescent peptide/MHC class I multimeric complexes incorporating mutations in the alpha3 domain (D227K/T228A) that abrogate binding to the CD8 coreceptor can be used to selectively isolate tumor Ag-specific T cells of high functional avidity from both in vitro expanded and ex vivo T cell populations. Sorting, cloning, and expansion of alpha3 domain mutant multimer-positive CD8 T cells enabled rapid selection of high avidity tumor-reactive T cell clones. Our results are relevant for ex vivo identification and isolation of T cells with potent antitumor activity for adoptive T cell therapy.
Resumo:
The recent advance in high-throughput sequencing and genotyping protocols allows rapid investigation of Mendelian and complex diseases on a scale not previously been possible. In my thesis research I took advantage of these modern techniques to study retinitis pigmentosa (RP), a rare inherited disease characterized by progressive loss of photoreceptors and leading to blindness; and hypertension, a common condition affecting 30% of the adult population. Firstly, I compared the performance of different next generation sequencing (NGS) platforms in the sequencing of the RP-linked gene PRPF31. The gene contained a mutation in an intronic repetitive element, which presented difficulties for both classic sequencing methods and NGS. We showed that all NGS platforms are powerful tools to identify rare and common DNA variants, also in case of more complex sequences. Moreover, we evaluated the features of different NGS platforms that are important in re-sequencing projects. The main focus of my thesis was then to investigate the involvement of pre-mRNA splicing factors in autosomal dominant RP (adRP). I screened 5 candidate genes in a large cohort of patients by using long-range PCR as enrichment step, followed by NGS. We tested two different approaches: in one, all target PCRs from all patients were pooled and sequenced as a single DNA library; in the other, PCRs from each patient were separated within the pool by DNA barcodes. The first solution was more cost-effective, while the second one allowed obtaining faster and more accurate results, but overall they both proved to be effective strategies for gene screenings in many samples. We could in fact identify novel missense mutations in the SNRNP200 gene, encoding an essential RNA helicase for splicing catalysis. Interestingly, one of these mutations showed incomplete penetrance in one family with adRP. Thus, we started to study the possible molecular causes underlying phenotypic differences between asymptomatic and affected members of this family. For the study of hypertension, I joined a European consortium to perform genome-wide association studies (GWAS). Thanks to the use of very informative genotyping arrays and of phenotipically well-characterized cohorts, we could identify a novel susceptibility locus for hypertension in the promoter region of the endothelial nitric oxide synthase gene (NOS3). Moreover, we have proven the direct causality of the associated SNP using three different methods: 1) targeted resequencing, 2) luciferase assay, and 3) population study. - Le récent progrès dans le Séquençage à haut Débit et les protocoles de génotypage a permis une plus vaste et rapide étude des maladies mendéliennes et multifactorielles à une échelle encore jamais atteinte. Durant ma thèse de recherche, j'ai utilisé ces nouvelles techniques de séquençage afin d'étudier la retinite pigmentale (RP), une maladie héréditaire rare caractérisée par une perte progressive des photorécepteurs de l'oeil qui entraine la cécité; et l'hypertension, une maladie commune touchant 30% de la population adulte. Tout d'abord, j'ai effectué une comparaison des performances de différentes plateformes de séquençage NGS (Next Generation Sequencing) lors du séquençage de PRPF31, un gène lié à RP. Ce gène contenait une mutation dans un élément répétable intronique, qui présentait des difficultés de séquençage avec la méthode classique et les NGS. Nous avons montré que les plateformes de NGS analysées sont des outils très puissants pour identifier des variations de l'ADN rares ou communes et aussi dans le cas de séquences complexes. De plus, nous avons exploré les caractéristiques des différentes plateformes NGS qui sont importantes dans les projets de re-séquençage. L'objectif principal de ma thèse a été ensuite d'examiner l'effet des facteurs d'épissage de pre-ARNm dans une forme autosomale dominante de RP (adRP). Un screening de 5 gènes candidats issus d'une large cohorte de patients a été effectué en utilisant la long-range PCR comme étape d'enrichissement, suivie par séquençage avec NGS. Nous avons testé deux approches différentes : dans la première, toutes les cibles PCRs de tous les patients ont été regroupées et séquencées comme une bibliothèque d'ADN unique; dans la seconde, les PCRs de chaque patient ont été séparées par code barres d'ADN. La première solution a été la plus économique, tandis que la seconde a permis d'obtenir des résultats plus rapides et précis. Dans l'ensemble, ces deux stratégies se sont démontrées efficaces pour le screening de gènes issus de divers échantillons. Nous avons pu identifier des nouvelles mutations faux-sens dans le gène SNRNP200, une hélicase ayant une fonction essentielle dans l'épissage. Il est intéressant de noter qu'une des ces mutations montre une pénétrance incomplète dans une famille atteinte d'adRP. Ainsi, nous avons commencé une étude sur les causes moléculaires entrainant des différences phénotypiques entre membres affectés et asymptomatiques de cette famille. Lors de l'étude de l'hypertension, j'ai rejoint un consortium européen pour réaliser une étude d'association Pangénomique ou genome-wide association study Grâce à l'utilisation de tableaux de génotypage très informatifs et de cohortes extrêmement bien caractérisées au niveau phénotypique, un nouveau locus lié à l'hypertension a été identifié dans la région promotrice du gène endothélial nitric oxide sinthase (NOS3). Par ailleurs, nous avons prouvé la cause directe du SNP associé au moyen de trois méthodes différentes: i) en reséquençant la cible avec NGS, ii) avec des essais à la luciférase et iii) une étude de population.
Resumo:
Møller-Plesset (MP2) and Becke-3-Lee-Yang-Parr (B3LYP) calculations have been used to compare the geometrical parameters, hydrogen-bonding properties, vibrational frequencies and relative energies for several X- and X+ hydrogen peroxide complexes. The geometries and interaction energies were corrected for the basis set superposition error (BSSE) in all the complexes (1-5), using the full counterpoise method, yielding small BSSE values for the 6-311 + G(3df,2p) basis set used. The interaction energies calculated ranged from medium to strong hydrogen-bonding systems (1-3) and strong electrostatic interactions (4 and 5). The molecular interactions have been characterized using the atoms in molecules theory (AIM), and by the analysis of the vibrational frequencies. The minima on the BSSE-counterpoise corrected potential-energy surface (PES) have been determined as described by S. Simón, M. Duran, and J. J. Dannenberg, and the results were compared with the uncorrected PES
Resumo:
The effect of basis set superposition error (BSSE) on molecular complexes is analyzed. The BSSE causes artificial delocalizations which modify the first order electron density. The mechanism of this effect is assessed for the hydrogen fluoride dimer with several basis sets. The BSSE-corrected first-order electron density is obtained using the chemical Hamiltonian approach versions of the Roothaan and Kohn-Sham equations. The corrected densities are compared to uncorrected densities based on the charge density critical points. Contour difference maps between BSSE-corrected and uncorrected densities on the molecular plane are also plotted to gain insight into the effects of BSSE correction on the electron density
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Geometries, vibrational frequencies, and interaction energies of the CNH⋯O3 and HCCH⋯O3 complexes are calculated in a counterpoise-corrected (CP-corrected) potential-energy surface (PES) that corrects for the basis set superposition error (BSSE). Ab initio calculations are performed at the Hartree-Fock (HF) and second-order Møller-Plesset (MP2) levels, using the 6-31G(d,p) and D95++(d,p) basis sets. Interaction energies are presented including corrections for zero-point vibrational energy (ZPVE) and thermal correction to enthalpy at 298 K. The CP-corrected and conventional PES are compared; the unconnected PES obtained using the larger basis set including diffuse functions exhibits a double well shape, whereas use of the 6-31G(d,p) basis set leads to a flat single-well profile. The CP-corrected PES has always a multiple-well shape. In particular, it is shown that the CP-corrected PES using the smaller basis set is qualitatively analogous to that obtained with the larger basis sets, so the CP method becomes useful to correctly describe large systems, where the use of small basis sets may be necessary
Resumo:
We used stepwise photochemical cross-linking for specifically assembling soluble and covalent complexes made of a T-cell antigen receptor (TCR) and a class I molecule of the major histocompatibility complex (MHC) bound to an antigenic peptide. For that purpose, we have produced in myeloma cells a single-chain Fv construct of a TCR specific for a photoreactive H-2Kd-peptide complex. Photochemical cross-linking of this TCR single-chain Fv with a soluble form of the photoreactive H-2Kd-peptide ligand resulted in the formation of a ternary covalent complex. We have characterized the soluble ternary complex and showed that it reacted with antibodies specific for epitopes located either on the native TCR or on the Kd molecules. By preventing the fast dissociation kinetics observed with most T cell receptors, this approach provides a means of preparing soluble TCR-peptide-MHC complexes on large-scale levels.
Resumo:
Using a direct binding assay based on photoaffinity labeling, we have studied the interaction of antigenic peptides with murine MHC class I molecules on living cells. Photoreactive derivatives were prepared by N-terminal amidation with iodo, 4-azido salicylic acid of the Kd restricted Plasmodium berghei circumsporozoite (P.b. CS) peptide 253-260 (YIPSAEKI) and the Db-restricted Adenovirus 5 early region 1A (Ad5 E1A) peptide 234-243 (SGPSNTPPEI). As assessed in functional competition experiments, both peptide derivatives retained the specific binding activity of the parental peptides for Kd or Dd, respectively. The P.b. CS photoprobe specifically labeled Kd molecules on P815 (H-2d) cells, but failed to label RMA (H-2b) cells. Conversely, the Ad5 E1A photoprobe specifically labeled Db molecules on RMA cells, but failed to label P815 cells. When the two photoprobes were tested on a panel of Con A-activated spleen cells expressing 10 different H-2 haplotypes, significant photoaffinity labeling was observed only on H-2d cells with the P.b. CS photoprobe and on H-2b cells with the Ad5 E1A photoprobe. Labeling of cell-associated Kd or Db molecules with the photoprobes was specifically inhibited by antigenic peptides known to be presented by the same class I molecule. Photoaffinity labeling of Kd with the P.b. CS photoprobe was used to study the dynamics of peptide binding on living P815 cells. Binding increased steadily with the incubation period (up to 8 h) at 37 degrees C and at ambient temperature, but was greatly reduced (greater than 95%) at 0 to 4 degrees C or in the presence of ATP synthesis inhibitors. The magnitude of the labeling was twofold higher at room temperature than at 37 degrees C. In contrast, binding to isolated Kd molecules in solution rapidly reached maximal binding, particularly at 37 degrees C. Dissociation of the photoprobe from either cell-associated or soluble Kd molecules was similar, with a half time of approximately 1 h at 37 degrees C, whereas the complexes were long-lived at 4 degrees C in both instances.