998 resultados para Critical Sequence


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With salaries subjected to scrutiny more than ever, it is increasingly important that the process by which they are determined be understood and justifiable. Both public and private organisations now routinely rely on so-called “job evaluation” as a means of constructing an appropriate pay-scale and as such it is ever more necessary that we appreciate how this system works and that we recognise its limits. Only with such an understanding of the way in which salaries are set can we hope to have a meaningful discussion of their economic function. This paper aims to expound the details of job evaluation both in theory and in practice, and critically assess its shortcomings. In Section 1 below we describe the job evaluation system and in Section 2 we briefly outline the history and the usage of the system in both the private and the public sector. In Section 3 we theoretically analyse the often unstated but nonetheless implicit assumptions made by practitioners of the art of job evaluation. Section 4 applies the analysis of Section 3 to review a particular and important case study, namely The Senior Salaries Review of the Welsh Assembly 2004. Section 5 concludes.

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Neonatal diabetes mellitus can be transient or permanent. The severe form of permanent neonatal diabetes mellitus can be associated with pancreas agenesis. Normal pancreas development is controlled by a cascade of transcription factors, where insulin promoter factor 1 (IPF1) plays a crucial role. Here, we describe two novel mutations in the IPF1 gene leading to pancreas agenesis. Direct sequence analysis of exons 1 and 2 of the IPF1 gene revealed two point mutations within the homeobox in exon 2. Genetic analysis of the parents showed that each mutation was inherited from one parent. Mutations localized in helices 1 and 2, respectively, of the homeodomain, decreased the protein half-life significantly, leading to intracellular IPF1 levels of 36% and 27% of wild-type levels. Both mutant forms of IPF1 were normally translocated to the nucleus, and their DNA binding activity on different known target promoters was similar to that of the wild-type protein. However, transcriptional activity of both mutant IPF1 proteins, alone or in combination with HNF3 beta/Foxa2, Pbx1, or the heterodimer E47-beta 2 was reduced, findings accounted for by decreased IPF1 steady state levels and not by impaired protein-protein interactions. We conclude that the IPF1 level is critical for human pancreas formation.

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The empirical finding of an inverse U-shaped relationship between per capita income and pollution, the so-called Environmental Kuznets Curve (EKC), suggests that as countries experience economic growth, environmental deterioration decelerates and thus becomes less of an issue. Focusing on the prime example of carbon emissions, the present article provides a critical review of the new econometric techniques that have questioned the baseline polynomial specification in the EKC literature. We discuss issues related to the functional form, heterogeneity, “spurious” regressions and spatial dependence to address whether and to what extent the EKC can be observed. Despite these new approaches, there is still no clear-cut evidence supporting the existence of the EKC for carbon emissions. JEL classifications: C20; Q32; Q50; O13 Keywords: Environmental Kuznets Curve; Carbon emissions; Functional form; Heterogeneity; “Spurious” regressions; Spatial dependence.Residential satisfaction is often used as a barometer to assess the performance of public policy and programmes designed to raise individuals' well-being. However, the fact that responses elicited from residents might be biased by subjective, non-observable factors casts doubt on whether these responses can be taken as trustable indicators of the individuals' housing situation. Emotional factors such as aspirations or expectations might affect individuals' cognitions of their true residential situation. To disentangle this puzzle, we investigated whether identical residential attributes can be perceived differently depending on tenure status. Our results indicate that tenure status is crucial not only in determining the level of housing satisfaction, but also regarding how dwellers perceive their housing characteristics. Keywords: Housing satisfaction, subjective well-being, homeownership. JEL classification: D1, R2.

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Cette thèse de doctorat, écrite en anglais, propose la première édition critique de « Because of the Dollars », une nouvelle de l'écrivain anglais Joseph Conrad publiée dans le volume Within the Tides, en février 1915. Outre le texte critique de la nouvelle - le seul à ce jour reconstruit d'après une minutieuse étude des relations entre toutes les versions existantes - la présente édition offre aussi un vaste apparat éditorial. Le texte de la présente édition est éclectique. Sa ponctuation est essentiellement basée sur un texte proche du manuscrit de l'auteur, et donc non corrompu par le processus de transmission. Mais ses mots sont tirés des dernières versions révisées par l'auteur, étant donné qu'au cours de la transmission, les mots, contrairement aux marques de ponctuation, n'ont pas été contaminés. Le résultat de cette méthode est un texte reflétant, tant pour les mots que pour la ponctuation, les choix de l'auteur. L'apparat éditorial sert à placer la nouvelle dans la vie de Conrad, tracer l'évolution du texte, et offrir au lecteur des informations historiques et culturelles qui permettront une meilleure lecture de l'oeuvre. Cet apparat est composé de quatre parties : une introduction, une étude sur les textes de la nouvelle, une collation historique de toutes les variantes, et des notes explicatives. L'introduction place l'oeuvre dans le contexte de la vie de l'écrivain, en donne la réception critique de 1915 à nos jours, et en éclaire le contexte historique (un changement de monnaie à Singapour en 1903-4). L'étude sur les textes trace le développement et la transmission du texte, depuis son inscription sur pages manuscrites jusqu'à sa publication dans les oeuvres complètes de Conrad. La collation historique inventorie toutes les variantes textuelles entre les différentes versions existantes. Enfin, les notes explicatives glosent les allusions littéraires, historiques, et culturelles du texte. « Because of the Dollars » et Within the Tides n'ayant attiré que très peu d'attention critique, les informations contenues dans cet apparat éditorial sont complètement inédites, et jettent une lumière originale sur une période peu étudiée de la vie de Conrad.

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Tandemly repeated DNA sequences are found in the genome of higher eukaryotes, and have also been demonstrated in Trypanosoma cruzi. Repeated DNA sequences are potentially useful for the diagnostic detection of T. cruzi (A. Gonzales et al., 1984, Proc. Natl. Acad. Sci. USA, 81: 3356-3360). We have isoleted two clones from a genomic library of T. cruzi (Y strain) that contain, in one clone a family of at least seven copies of a repetitive sequence of approximately 600 base pairs, and in the other an independent copy of the same sequence. One copy of the repetition (HSP) and the independent clone (HCR) were sequenced by the Sanger procedure (Fig.). This sequence hybridized to four strains of T. cruzi tested and did not hybridize to eleven species of trypanosotids from five different Genera, being a good candidate for diagnostic assays. GenBank accession numbers: HSP#m31919, HCR#31920.

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Microarray transcript profiling and RNA interference are two new technologies crucial for large-scale gene function studies in multicellular eukaryotes. Both rely on sequence-specific hybridization between complementary nucleic acid strands, inciting us to create a collection of gene-specific sequence tags (GSTs) representing at least 21,500 Arabidopsis genes and which are compatible with both approaches. The GSTs were carefully selected to ensure that each of them shared no significant similarity with any other region in the Arabidopsis genome. They were synthesized by PCR amplification from genomic DNA. Spotted microarrays fabricated from the GSTs show good dynamic range, specificity, and sensitivity in transcript profiling experiments. The GSTs have also been transferred to bacterial plasmid vectors via recombinational cloning protocols. These cloned GSTs constitute the ideal starting point for a variety of functional approaches, including reverse genetics. We have subcloned GSTs on a large scale into vectors designed for gene silencing in plant cells. We show that in planta expression of GST hairpin RNA results in the expected phenotypes in silenced Arabidopsis lines. These versatile GST resources provide novel and powerful tools for functional genomics.

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Cytotoxic T cells (CTL) recognize short peptides that are derived from the proteolysis of endogenous cellular proteins and presented on the cell surface as a complex with MHC class I molecules. CTL can recognize single amino acid substitutions in proteins, including those involved in malignant transformation. The mutated sequence of an oncogene may be presented on the cell surface as a peptide, and thus represents a potential target antigen for tumour therapy. The p21ras gene is mutated in a wide variety of tumours and since the transforming mutations result in amino acid substitutions at positions 12, 13 and 61 of the protein, a limited number of ras peptides could potentially be used in the treatment of a wide variety of malignancies. A common substitution is Val for Gly at position 12 of p21ras. In this study, we show that the peptide sequence from position 5 to position 14 with Val at position 12-ras p5-14 (Val-12)-has a motif which allows it to bind to HLA-A2.1. HLA-A2.1-restricted ras p5-14 (Val-12)-specific CTL were induced in mice transgenic for both HLA-A2.1 and human beta2-microglobulin after in vivo priming with the peptide. The murine CTL could recognize the ras p5-14 (Val-12) peptide when they were presented on both murine and human target cells bearing HLA-A2.1. No cross-reactivity was observed with the native peptide ras p5-14 (Gly-12), and this peptide was not immunogenic in HLA-A2.1 transgenic mice. This represents an interesting model for the study of an HLA-restricted CD8 cytotoxic T cell response to a defined tumour antigen in vivo.

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The human auditory system is comprised of specialized but interacting anatomic and functional pathways encoding object, spatial, and temporal information. We review how learning-induced plasticity manifests along these pathways and to what extent there are common mechanisms subserving such plasticity. A first series of experiments establishes a temporal hierarchy along which sounds of objects are discriminated along basic to fine-grained categorical boundaries and learned representations. A widespread network of temporal and (pre)frontal brain regions contributes to object discrimination via recursive processing. Learning-induced plasticity typically manifested as repetition suppression within a common set of brain regions. A second series considered how the temporal sequence of sound sources is represented. We show that lateralized responsiveness during the initial encoding phase of pairs of auditory spatial stimuli is critical for their accurate ordered perception. Finally, we consider how spatial representations are formed and modified through training-induced learning. A population-based model of spatial processing is supported wherein temporal and parietal structures interact in the encoding of relative and absolute spatial information over the initial ∼300ms post-stimulus onset. Collectively, these data provide insights into the functional organization of human audition and open directions for new developments in targeted diagnostic and neurorehabilitation strategies.

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Establishing CD8(+) T cell cultures has been empirical and the published methods have been largely individual laboratory based. In this study, we optimized culturing conditions and show that IL-2 concentration is the most critical factor for the success of establishing CD8(+) T cell cultures. High IL-2 concentration encouraged T cells to non-specifically proliferate, express a B cell marker, B220, and undergo apoptosis. These cells also lose typical irregular T cell morphology and are incapable of sustaining long-term cultures. Using tetramer and intracellular cytokine assessments, we further demonstrated that many antigen-specific T cells have been rendered nonfunctional when expanded under high IL-2 concentration. When IL-2 is used in the correct range, B220-mediated cell depletion greatly enhanced the success rate of such T cell cultures.

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SUMMARY Genomic imprinting is an epigenetic mechanism of transcriptional regulation that ensures restriction of expression of a subset of mammalian genes to a single parental allele. The best studied example of imprinted gene regulation is the Igf2/H19 locus, which is also the most commonly altered by loss of imprinting (LOT) in cancer. LOT is associated with numerous hereditary diseases and several childhood, and adult cancers. Differential expression of reciprocal H19 and 1gf2 alleles in somatic cells depends on the methylation status of the imprinting control region (ICR) which regulates binding of CTCF, an ubiquitously expressed 11-zinc finger protein that binds specifically to non-methylated maternal ICR and thereby attenuates expression of Igf2, while it does not bind to methylated paternal ICR, which enables Igf2 expression. Initial ICR methylation occurs during gametogenesis by an as yet unknown mechanism. The accepted hypothesis is that the event of differential maternal and paternal DNA methylation depends on germ-line specific proteins. Our Laboratory identified a novel 11-zinc-finger protein CTCF-T (also known as CTCFL and BORIS) that is uniquely expressed in the male germ-line and is highly homologous within its zinc-finger region with CTCF. The amino-acid sequences flanking the zinc-finger regions of CTCF and CTCF-T have widely diverged, suggesting that though they could bind to the same DNA targets (ICRs) they are likely to have different functions. Interestingly, expression of CTCF-T and CTCF is mutually exclusive; CTCF-T-positive (CTCF-negative) cells occur in the stage of spermatogenesis that coincides with epigenetic reprogramming, including de novo DNA methylation. In our study we demonstrate the role that CTCF-T plays in genomic imprinting. Here we show that CTCF-T binds in vivo to the ICRs of Igf2/H19 and Dlk/Gt12 imprinted genes. In addition, we identified two novel proteins interacting with CTCF-T: a protein arginine methyltransferase PRMT7 and an arginine-rich histone H2A variant that we named trH2A. These interactions were confirmed and show that the two proteins interact with the amino-teiminal region of CTCF-T. Additionally, we show interaction of the amino- terminal region of CTCF-T with histones H1, H2A and H3. These results suggest that CTCF-T is a sequence-specific DNA (ICR) binding protein that associates with histones and recruits PRMT7. Interestingly, PRMT7 has a histone-methyltransferase activity. It has been shown that histone methylation can mark chromatin regions thereby directing DNA-methylation; thus, our hypothesis is that the CTCF-T protein-scaffold directs PRMT7 to methylate histone(s) assembled on ICRs, which marks chromatin for the recruitment of the de novo DNA methyltransferases to methylate DNA. To test this hypothesis, we developed an in vivo DNA-methylation assay using Xenopus laevis' oocytes, where H19 ICR and different expression cDNAs, including CTCF-T, PRMT7 and the de novo DNA methyltransferases (Dnmt3a, Dnmt3b and Dnmt3L) are microinjected into the nucleus. The methylation status of CpGs within the H19 ICR was analysed 48 or 72 hours after injection. Here we demonstrate that CpGs in the ICR are methylated in the presence of both CTCF-T and PRMT7, while control oocytes injected only with ICR did not show any methylation. Additionally, we showed for the first time that Dnmt3L is crucial for the establishment of the imprinting marks on H19 ICR. Moreover, we confirmed that Dnmt3a and Dnmt3b activities are complementary. Our data indicate that all three Dnmt3s are important for efficient de novo DNA methylation. In conclusion, we propose a mechanism for the establishment of de novo imprinting marks during spermatogenesis: the CTCF-T/PRMT7 protein complex directs histone methylation leading to sequence-specific de novo DNA methylation of H19 ICR. RESUME L'empreinte génomique parentale est un mécanisme épigénétique de régulation transcriptionelle qui se traduit par une expression différentielle des deux allèles de certains gènes, en fonction de leur origine parentale. L'exemple le mieux caractérisé de gènes soumis à l'empreinte génomique parentale est le locus Igf2/H19, qui est aussi le plus fréquemment altéré par relaxation d'empreinte (en anglais: loss of imprinting, LOI) dans les cancers. Cette relaxation d'empreinte est aussi associée à de nombreuses maladies héréditaires, ainsi qu'à de nombreux cancers chez l'enfant et l'adulte. Dans les cellules somatiques, les différences d'expression des allèles réciproques H19 et Ig12 est sous le contrôle d'une région ICR (Imprinting Control Region). La méthylation de cette région ICR régule l'ancrage de la protéine à douze doigts de zinc CTCF, qui se lie spécifiquement à l'ICR maternel non-méthylé, atténuant ainsi l'expression de Igf2, alors qu'elle ne s'ancre pas à l'ICR paternel méthyle. Le mécanisme qui accompagne la méthylation initiale de la région ICR durant la gamétogenèse n'a toujours pas été élucidé. L'hypothèse actuelle propose que la différence de méthylation entre l'ADN maternel et paternel résulte de l'expression de protéines propres aux zones germinales. Notre laboratoire a récemment identifié une nouvelle protéine à douze doigts de zinc, CTCF-T (aussi dénommée CTCFL et BORRIS), qui est exprimée uniquement dans les cellules germinales mâles, dont la partie à douze doigts de zinc est fortement homologue à la protéine CTCF. La séquence d'acides aminés de part et d'autre de cette région est quant à elle très divergente, ce qui implique que CTCF-T se lie sans doute au même ADN cible que CTCF, mais possède des fonctions différentes. De plus, l'expression de CTCF-T et de CTCF s'oppose mutuellement; l'expression de la protéine CTCF-T (cellules CTCF-T positives, CTCF negatives) qui a lieu pendant la spermatogenèse coïncide avec la reprogrammation épigénétique, notamment la méthylation de novo de l'ADN. La présente étude démontre le rôle essentiel joué par la protéine CTCF-T dans l'acquisition de l'empreinte génomique parentale. Nous montrons ici que CTCF-T s'associe in vivo avec les régions ICR des loci Igf2/H19 et Dlk/Gt12. Nous avons également identifié deux nouvelles protéines qui interagissent avec CTCF-T : une protéine arginine méthyl transférase PRMT7, et un variant de l'histone H2A, riche en arginine, que nous avons dénommé trH2A. Ces interactions ont été analysées plus en détail, et confinnent que ces deux protéines s'associent avec la région N-terminale de CTCF-T. Aussi, nous présentons une interaction de la région N-terminale de CTCF-T avec les histones H1, H2, et H3. Ces résultats suggèrent que CTCF-T est une protéine qui se lie spécifiquement aux régions ICR, qui s'associe avec différents histones et qui recrute PRMT7. PRMT7 possède une activité méthyl-tansférase envers les histones. Il a été montré que la méthylation des histones marque certains endroits de la chromatine, dirigeant ainsi la méthylation de l'ADN. Notre hypothèse est donc la suivante : la protéine CTCF-T sert de base qui dirige la méthylation des histones par PRMT7 dans les régions ICR, ce qui contribue à marquer la chromatine pour le recrutement de nouvelles méthyl transférases pour méthyler l'ADN. Afin de valider cette hypothèse, nous avons développé un système de méthylation de l'ADN in vivo, dans des oeufs de Xenopus laevis, dans le noyau desquels nous avons mico-injecté la région ICR du locus H19, ainsi que différents vecteurs d'expression pour CTCF-T, PRMT7, et les de novo méthyl transférases (Dnmt3a, Dnmt3b et Dnmt3L). Les CpGs méthyles de la région ICR du locus H19 ont été analysé 48 et 72 heures après l'injection. Cette technique nous a permis de démontrer que les CpGs de la région ICR sont méthyles en présence de CTCF-T et de PRMT7, tandis que les contrôles injectés seulement avec la région ICR ne présentent aucun signe de méthylation. De plus, nous démontrons pour la première fois que la protéine méthyl transférase Dnmt3L est déterminant pour l'établissement de l'empreinte génomique parentale au niveau de la région ICR du locus H19. Aussi, nous confirmons que les activités méthyl transférases de Dnmt3a et Dnmt3b sont complémentaires. Nos données indiquent que les trois protéines Dnmt3 sont impliquées dans la méthylation de l'ADN. En conclusion, nous proposons un mécanisme responsable de la mise en place de nouvelles empreintes génomiques pendant la spermatogenèse : le complexe protéique CTCF-T/PRMT7 dirige la méthylation des histones aboutissant à la méthylation de novo de l'ADN au locus H19.

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Plant-parasitic nematodes are major agricultural pests worldwide and novel approaches to control them are sorely needed. We report the draft genome sequence of the root-knot nematode Meloidogyne incognita, a biotrophic parasite of many crops, including tomato, cotton and coffee. Most of the assembled sequence of this asexually reproducing nematode, totaling 86 Mb, exists in pairs of homologous but divergent segments. This suggests that ancient allelic regions in M. incognita are evolving toward effective haploidy, permitting new mechanisms of adaptation. The number and diversity of plant cell wall-degrading enzymes in M. incognita is unprecedented in any animal for which a genome sequence is available, and may derive from multiple horizontal gene transfers from bacterial sources. Our results provide insights into the adaptations required by metazoans to successfully parasitize immunocompetent plants, and open the way for discovering new antiparasitic strategies.

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Urease is an important virulence factor for Helicobacter pylori and is critical for bacterial colonization of the human gastric mucosa. Specific inhibition of urease activity has been proposed as a possible strategy to fight this bacteria which infects billions of individual throughout the world and can lead to severe pathological conditions in a limited number of cases. We have selected peptides which specifically bind and inhibit H. pylori urease from libraries of random peptides displayed on filamentous phage in the context of pIII coat protein. Screening of a highly diverse 25-mer combinatorial library and two newly constructed random 6-mer peptide libraries on solid phase H. pylori urease holoenzyme allowed the identification of two peptides, 24-mer TFLPQPRCSALLRYLSEDGVIVPS and 6-mer YDFYWW that can bind and inhibit the activity of urease purified from H. pylori. These two peptides were chemically synthesized and their inhibition constants (Ki) were found to be 47 microM for the 24-mer and 30 microM for the 6-mer peptide. Both peptides specifically inhibited the activity of H. pylori urease but not that of Bacillus pasteurii.

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The P126 protein, a parasitosphorus vacuole antigen of Plasmodium falciparum has beenshoen to induce protective immunity in Saimiri and Aotus monkeys. In the present work we investigated its immunogenicity. Our results suggest that the N-term of P126 is poorly immunogenic and antibody response against the P126 could be under a MHC restricted control in C57BL/6(H-2b) mice, which could be problematic in ternms of a use of the P126 in a vaccine program. However, we observed that a synthetic peptide, copying the 6 octapeptide repeat corresponding to the N-term of the P126, induces an antibody response to the native molecule in C57BL/6 non-responder mice. Moreover, the vaccine-P126 recombinant induced anmtibodies against the N-term of the molecule in rabbits while the unprocessed P126 did not.