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Fatores genéticos e clínicos relacionados à infecções pelo HIV-1 e HTLV-1.Rego, Filipe Ferreira de Almeida January 2014 (has links)
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Previous issue date: 2014 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, Ba, Brasil / Nesta tese foram realizados três trabalhos distintos sendo que todos envolvem identificar
possíveis fatores genéticos ou clínicos relacionados com a infecção pelo HIV-1 ou pelo
HTLV-1 ou por ambos. No primeiro trabalho nós objetivamos identificar mutações que
poderiam estar relacionadas com o desenvolvimento da TSP/HAM ou carga proviral. Para
isto sequenciamos a região LTR5’ do HTLV-1 por Ion Torrent para verificar mutações com
baixa frequência. Nós encontramos mutações em 52 posições que estavam presentes em mais
de um indivíduo, porém apenas 11 destas estavam presentes em TFBS previamente descritos.
Três mutações que não estavam presentes em TFBS previamente descritos foram
estatisticamente significantes quando comparadas entre os grupos," sendo" que" estes" sítios"
podem" ser" importantes" para" a"mediação" da" transcrição" viral."No" segundo" estudo" nós"
objetivamos determinar a prevalência do genótipo selvagem em Hlabisa, Kwazulu-Natal na
África do Sul além de identificar possíveis fatores associados a presença deste genótipo em
220 pacientes submetidos a ART. O genótipo selvagem foi detectado em 28 amostras
(12,7%). Selecionamos 11 pacientes para realizar o sequenciamento pelo Ion Torrent, nove
confirmaram não ter mutações de resistência aos antirretrovirais em alta frequência. Foi
encontrada uma alta contagem de CD4+ no início da terapia associado a falha terapêutica
assim como uma alta carga viral antes da genotipagem e não foi encontrado associação entre
aderência a terapia auto-reportada e a presença do genótipo selvagem. Aproximadamente um
em cada oito adultos que falham a terapia possuem o genótipo selvagem sendo este dado
confirmado através de sequenciamento de nova geração. Devido ao alto número de genótipos
selvagem encontrados, o teste de resistência genotípica deve ser solicitado para se obter um
melhor desfecho clinico em níveis individuais e populacionais. No terceiro estudo nós
analisamos as diferenças na contagem de linfócitos T CD4+ entre indivíduos infectados
apenas com o HIV-1 e indivíduos coinfectados HIV-1/HTLV-1 com falha terapêutica, além
de analisarmos a soroprevalência do HTLV-1 em indivíduos infectados pelo HIV-1. Foram
encontrados oito pacientes coinfectados (2,1%) dos 381 pacientes analisados. Nós não
observamos nenhuma diferença estatística quando analisamos transversalmente os dados
clínicos dos pacientes, exceto na primeira contagem de linfócitos T CD4+ após o início do
tratamento que estava maior nos indivíduos coinfectados (p=0.03). A análise multivariada
longitudinal mostrou que a media de linfócitos T CD4+ ao longo do tratamento, foi
estatisticamente maior nos pacientes coinfectados levando em consideração características
demográficas, carga viral, fatores relacionados a terapia, entre outros. Nos pacientes
coinfectados também não foram encontrados marcadores de HLA relacionados com os
supressores de elite do HIV-1. Os dados deste trabalho sugerem que os pacientes coinfectados
em terapia antirretroviral deveriam ter um acompanhamento clínico diferenciado dos
indivíduos apenas infectados pelo HIV-1, pois a coinfecção poderia estar levando ao aumento
do número dos linfócitos T CD4+ sem um possível ganho de resposta imune. / We performed three studies to analyze risk factors associated with retroviruses infections. In
the first study we attempted to analyze mutations related to TSP/HAM development or
proviral load. For that purpose we have sequenced the LTR 5’ region of HTLV-1 by Ion
Torrent. We found that mutations in 52 positions were present in more than one individual,
but only 11 were present in the previously described TFBS. Three mutations that were not
present in the previously described TFBS were statistically significant comparing groups.
Despite the absence of previously described TFBS, these sites might be important for the viral
transcription. In the second study we analyzed the prevalence of HIV-1 wild type genotype in
adults failing first-line ART. A total of 220 adults were included. The wild type genotype was
detected by population sequencing in 28 (12.7%). No major drug resistance mutations were
detected by deep sequencing for 81.8% (9/11) of those sampled. Higher baseline CD4+ cell
count was associated with a greater likelihood of wild type genotype as was a higher viral
load prior to resistance testing but there was no evidence of an association between selfreported
adherence and the presence of wild type genotype. Approximately one in eight adults
failing first-line ART had wild type genotype and this result was confirmed trough deep
sequencing in some samples. Access to genotypic resistance testing may be required in this
region to achieve optimal individual-level and population-level outcomes. In the third study
we proposed to verify the prevalence of HTLV-1 and to statistically assess differences in
CD4+ counts between HTLV-1/HIV-1 co-infected and HIV-1 mono-infected patients living
in rural KwaZulu-Natal. The HTLV-1 seroprevalence was 2.1% (8 out 381 patients). The
patients were grouped by HTLV-1/HIV-1 co-infected and HIV-1 mono-infected status for the
statistical analysis. There were no cross-sectional differences between the groups regarding
CD4+ count before therapy, CD4+ count at genotype, age, gender, viral load, duration of
ART, immunological failure, ART failure and first ART regimen. However, the first CD4+
count after treatment was higher in the co-infected group (p=0.03). A multivariate,
longitudinal model showed that the mean CD4+ count over time for the HTLV-1/HIV-1 coinfected
group was significantly higher than the HIV mono-infected group (p<0.05) when
adjusting for demographic characteristics, viral load and ART treatment factors. This finding
was independent of expression of HLA Class 1 genotypes previously associated with HIV-1
infected elite suppressors. This study suggests that the increase of CD4+ count after therapy
suggests a differential clinical management for the HTLV-1/HIV-1 co-infected patients
should be implemented.
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Structural and functional characterization of giant plant Ogre-like retrotransposons / Structural and functional characterization of giant plant Ogre-like retrotransposonsSTEINBAUEROVÁ, Veronika January 2012 (has links)
Ogre elements represent a distinct group of Ty3/gypsy LTR retrotransposons occurring in a range of dicot plants. They are characterized by two specific features ? presence of long extra open reading frame in 5´ untranslated region with unknown function and a non-coding sequence containing several stop codons separating protease and reverse transcriptase domains which was proposed to be removed by splicing. This thesis describes the functional analysis of intron splicing in Ogre retrotransposons. Further, it investigates additional coding information not only in Ogre retrotransposons but in the whole group of Ty3/gypsy retroelements.
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Bioinformatický nástroj pro anotaci transposonů / Bioinformatics Tool for Transposons AnnotationJenčo, Michal January 2017 (has links)
This thesis provides theoretical resources for the design of a new bioinformatics tool for transposon annotation with focus on their additional structural elements. There is a biological description of transposons, the mobile elements in DNA, their classification and structure. It further deals with the overview and classification of available transposon identification and annotation bioinformatics tools, description of function and implementation of a select few. Next we state the scheme of a new bioinformatics tool for LTR retrotransposon identification and annotation with a focus on extra ORFs and tandem repeats. The functionality of this new tool was tested on the A. thaliana genome. We identified 95 groups of conserved extra ORFs and 10 groups of conserved tandem repeats.
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Implication de la méthylation dans le contrôle de l'expression de rétrovirus endogènes humains en contextes physiologiques et pathologiques / Implication of DNA methylation in the control of human endogenous retroviruses expression in physiological and pathological contextsGimenez, Juliette 19 November 2009 (has links)
Les rétrovirus endogènes (ERV) sont des éléments constitutifs de la plupart des génomes eucaryotes, et représentent chez l’humain environ 400000 loci. Les HERV sont divisés en familles distinctes, composées d’éléments apparentés mais structurellement hétérogènes. Leur activité peut être néfaste, neutre, mais aussi bénéfique. La majorité des HERV semble silencieuse dans les cellules somatiques. Cependant certains présentent une forte activité en contextes physiologiques. Par ailleurs, une expression significative de HERV est fréquemment observée dans des contextes pathologiques, tels que les cancers. La mise sous silence des éléments répétés est supposée se produire principalement par la méthylation de leur ADN. Nous nous sommes donc intéressés à l’implication de la méthylation des régions régulatrices des HERV, les LTR, dans le contrôle de leur expression. D’une part cette étude nous a permis de mettre en évidence une méthylation locus- et tissu- spécifique de LTR HERV en contexte physiologique, impliquant notamment des modalités particulières de méthylation contrôlant l’expression placentaire de HERV domestiqués. D’autre part ce travail nous a permis de déterminer que six loci HERV-W, incluant un locus domestiqué, sont réactivés de manière autonome dans des tumeurs testiculaires sous l’influence d’un changement de modalité de méthylation intra-famille. Ainsi la méthylation des HERV influence leur expression, mais sous des modalités variables selon les loci et les contextes concernés / Endogenous retroviruses are constitutive elements of most eukaryotic genomes. They represent about 400,000 loci in the human genome. HERVs are divided into distinct families on the basis of phylogenetic identities but are highly heterogeneous in structures. Their activity can be detrimental, neutral, or beneficial to the host. Majority of HERVs seems silent in somatic cells. Still, some are highly expressed in physiological contexts. Besides, a significant expression of HERVs is frequently observed in pathological contexts such as cancers. Silencing of repeated elements is supposed to occur mainly through DNA methylation. We were therefore interested by the implication of HERV regulatory region (LTR) methylation in the control of their expression. First, this study identified locus and tissues –specific HERV LTR methylation in physiological context, worth noting particular methylation modalities that control domesticated HERVs placental expression. Second, we could determine a change in intra-family LTR methylation modalities in testicular tumors leading to the autonomous reactivation of six HERV-W loci, among which a domesticated one. Thus methylation clearly influences HERVs expression, but under modalities varying upon the loci and the contexts
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Um estudo sobre raios de estabilidade real e complexo e valores singulares estruturados / not availableTicona Masca, Gregoria Magda 08 January 1999 (has links)
Neste trabalho, duas técnicas de controle robusto (LQG/LTR e DML), aplicadas a um sistema elétrico de potência, são avaliadas através dos raios de estabilidade do sistema. As incertezas estruturadas do modelo nominal são consideradas nos dois controladores. Um conjunto de modelos é gerado considerando as combinações das incertezas paramétricas. Os valores singulares estruturados dos dois sistemas de controle são analisados. / In this work, two techniques of robust control (LQG/LTR) and LMI), applied to a power electric system, are available via stability radii of the system. The structured uncertainties of the nominal model are considered in both designs. A set of models is generated considering the combinations of the parametric uncertainties. The structured singular values of both systems are analysed.
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Étude du transcriptome des rétrovirus endogènes humains et implications fonctionnelles : applications à la recherche de marqueurs diagnostiques de cancers / Study of the transcriptome of human endogenous retroviruses and functional implications : applications to the search for diagnostic markers of cancersPerot, Philippe 29 November 2012 (has links)
Le génome humain contient environ 200 000 séquences d'origine rétrovirale (HERV), intégrées au fil de l'évolution et organisées aujourd'hui en familles multicopies complexes globalement réprimées par un contrôle épigénétique. L'étude du transcriptome HERV au niveau locus est compliquée par les similarités phylogénétiques au sein d'une famille et par la profusion des sites d'intégration, deux propriétés inhérentes aux éléments transposables. Dans ce travail, nous avons utilisé une méthode de conception de sondes de détection de 25 mer afin d'adresser la question de l'expression individuelle des HERV. Une puce à ADN haute densité intégrant plus de 5 500 séquences HERV et permettant une lecture fonctionnelle de l'activité de leurs LTRs a été utilisée sur un panel de tissus sains et cancéreux. Cela a permis d'identifier 1 718 séquences HERV actives, dont 326 LTRs promotrices et 209 LTRs polyA. L’étude de l’environnement génomique a mis en évidence une fenêtre d’environ 8 kb en amont des LTRs promotrices, caractérisée par une sous-représentation en gènes cellulaires en orientation sens. Nous avons également montré que le transcriptome des rétrovirus endogènes humains suit des règles de tropisme d’expression, qu’il est sensible aux états de différenciation cellulaire et qu’il ne semble pas être corrélé à l’âge des familles. Une première tentative d’exploitation de ce répertoire HERV dans un contexte clinique a visé à rechercher de nouveaux marqueurs diagnostiques du cancer de la prostate à partir de prélèvements urinaires, par la réalisation d’une étude pilote sur 45 patients / The human genome contains around 200,000 endogenous retroviral sequences (HERV) integrated during the evolution and which are nowadays organized into complex multicopy families, globally repressed by epigenetic control. The study of the HERV transcriptome at the locus level is complicated by phylogenetic similarities within one family and by the profusion of integration sites, two inherent characteristics of transposable elements. In this work, we used a method aiming to optimally characterize individual loci associated with 25 mer probes. A custom microarray dedicated to more than 5,500 HERV sequences and allowing a functional interpretation of the LTRs expression was used on a panel of normal and tumor tissues. We therefore identified 1,718 active HERV sequences, including 326 promoter LTRs and 209 polyA LTRs. The study of the genomic environment has highlighted an approximately 8 kb zone upstream of promoter LTRs characterized by a drastic reduction in sense cellular genes. We also showed that the HERV transcriptome follows tropism rules, is sensitive to the state of cell differentiation and, unexpectedly, seems not to correlate with the age of the families. In a first attempt to use the HERV repertoire in clinical, we sought to identify new markers of prostate cancer from urine samples. This goal was pursued by conducting a pilot study on 45 patients
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Molekulare Charakterisierung von Ty3-gypsy-Retrotransposons als abundante Sequenzklasse des Centromers eines Minichromosoms in Beta vulgaris L.Weber, Beatrice 10 February 2008 (has links) (PDF)
Die Gattung Beta gehört zur Familie der Chenopodiaceae und wird in die vier Sektionen Beta, Corollinae, Nanae und Procumbentes unterteilt, wobei die Zuckerrübe der Sektion Beta zugeordnet wird. Aus dem Genom der Zuckerrübe und verwandter Wildarten konnten bereits eine Vielzahl von repetitiven DNA-Familien kloniert und untersucht werden. Mit der monosomen Fragmentadditionslinie PRO1 stand eine Chromosomenmutante zur Verfügung, die neben den 18 B. vulgaris-Chromosomen ein Chromosomenfragment der Wildrübe Beta procumbens enthält. Da dieses als Minichromosom bezeichnete Fragment mitotische Stabilität aufweist, muss es ein funktionelles Centromer besitzen, das auch im genetischen Hintergrund von Beta vulgaris aktiv ist. Mit der Erstellung einer BAC (bacterial artifical chromosome)-Bank von PRO1 wurde die molekulare Charakterisierung von Ty3-gypsy-Retrotransposons eines einzelnen Wildrüben-Centromers möglich. Die für die Wildrübe Beta procumbens spezifischen Satellitenrepeats pTS5 und pTS4.1 dienten der Selektion von BACs aus der Centromer-Region des PRO1-Minichromosoms. Die Identifizierung eines unikalen genomischen Locus, mit einer Verschachtelung von zwei nicht homologen LTR-Retrotransposons, ermöglichte die gerichtete Isolation der LTR-Retrotransposons Beetle1 und Beetle2. Das Retrotransposon Beetle1 hat eine Gesamtlänge von 6736 bp und wird von LTR-Sequenzen begrenzt, die eine Länge von 1091 bp (5’-LTR) bzw. 1089 bp (3’-LTR) aufweisen. Das LTR-Retrotransposon Beetle2 weist mit 6690 bp eine ähnliche Gesamtlänge wie Beetle1 auf. Es wird von deutlich kürzeren LTR-Sequenzen mit einer Länge von 774 bp begrenzt. Aufgrund der Reihenfolge der Polyproteingene lassen sich Beetle1 und Beetle2 in die Gruppe der Ty3-gypsy-Retrotransposons (Metaviridae) einordnen. Beide Retrotransposon-Familien besitzen ein einziges offenes Leseraster (open reading frame; ORF) mit fusionierten gag- und pol-Genen. Datenbankrecherchen zeigten hohe Homologien von Beetle1 und Beetle2 mit den centromerischen Ty3-gypsy-Retrotransposons CRM aus Zea mays, CRR aus Oryza sativa und cereba aus Hordeum vulgare. Diese centromerischen Retrotransposons (CRs) sind in den Poaceae stark konserviert und stellen neben Satellitenrepeats eine hochabundante Sequenzklasse der Centromere der Süßgräser dar. Da sie im 3’-Bereich des gag-pol-Polyproteins eine Chromodomäne aufweisen, werden sie der eigenständigen Gruppe der Chromoviren zugeordnet. Chromodomänen sind zur Bindung von Proteinen und DNA befähigt und spielen eine wichtige Rolle in der Chromatin-Modifikation und der Bildung von Heterochromatin-Regionen. Beetle1 und Beetle2 besitzen Motive einer Chromodomäne, die vermutlich für eine gerichtete Transposition in die Centromer-Region verantwortlich ist. Neben der geringen Divergenz von Beetle1- und Beetle2-Sequenzen sowohl im Genom von Beta procumbens als auch in den anderen Arten der Sektion Procumbentes spricht auch das junge Alter von 100 000 bis 350 000 Jahren und die Transkriptionsaktivität für eine Einordnung dieser Ty3-gypsy-Retrotransposons in die Gruppe der Chromoviren. Sowohl die Southern-Hybridisierung als auch die Fluoreszenz-in situ-Hybridisierung zeigten, dass Beetle1 und Beetle2 nur für die Sektion Procumbentes spezifisch sind und dort in hoher Kopienzahl vorkommen. Untersuchungen mit methylierungssensitiven Restriktionsendonukleasen veranschaulichten den hohen Grad an Cytosin-Methylierung von Beetle1 und Beetle2.
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Um estudo sobre raios de estabilidade real e complexo e valores singulares estruturados / not availableGregoria Magda Ticona Masca 08 January 1999 (has links)
Neste trabalho, duas técnicas de controle robusto (LQG/LTR e DML), aplicadas a um sistema elétrico de potência, são avaliadas através dos raios de estabilidade do sistema. As incertezas estruturadas do modelo nominal são consideradas nos dois controladores. Um conjunto de modelos é gerado considerando as combinações das incertezas paramétricas. Os valores singulares estruturados dos dois sistemas de controle são analisados. / In this work, two techniques of robust control (LQG/LTR) and LMI), applied to a power electric system, are available via stability radii of the system. The structured uncertainties of the nominal model are considered in both designs. A set of models is generated considering the combinations of the parametric uncertainties. The structured singular values of both systems are analysed.
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Rekonstrukce repetitivních elementů DNA / Reconstruction of Repetitive Elements in DNAHypský, Jan January 2018 (has links)
Eukaryotic genomes contain a large number of repetitive structures. Their detection and assembly today are the main challenges of bioinformatics. This work includes a classification of repetitive DNA and represents an implementation of a novel de novo assembler focusing on searching and constructing LTR retrotransposons and satellite DNA. Assembler accepts on his input short reads (single or pair-end), obtained from next-generation sequencing machines (NGS). This assembler is based on Overlap Layout Consensus approach.
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CHARACTERIZATION AND DISTRIBUTION OF NOVEL NON-LTR RETROELEMENTS DRIVING HIGH TELOMERE RFLP DIVERSITY IN CLONAL LINES OF MAGNAPORTHE ORYZAEStarnes, John H 01 January 2013 (has links)
The filamentous ascomycete fungus Magnaporthe oryzae is a pathogen of over 50 genera of grasses. Two important diseases it can cause are gray leaf spot in Lolium perenne (perennial ryegrass) and blast in Oryza sativa (rice). The telomeres of M. oryzae isolates causing gray leaf spot are highly variable, and can spontaneously change during fungal culture. In this dissertation, it is shown that a rice-infecting isolate is much more stable at the telomeres than an isolate from gray leaf spot. To determine the molecular basis of telomere instability several gray leaf spot isolates telomeres were cloned, which revealed two non-LTR retrotransposons inserted into the telomere repeats. The elements have been termed Magnaporthe oryzae Telomeric Retrotransposons (MoTeRs). These elements do not have poly-A tails common to many other non-LTR retrotransposons, but instead have telomere like sequences at their 5’ end that allow them to insert into telomeres. Intact copies of MoTeRs were restricted to the telomeres of isolates causing gray leaf spot. Surveys for the presence of these elements in M. oryzae showed they were present in several host-specialized forms including gray leaf spot isolates, but were largely absent in the rice blast isolates. The absence of MoTeRs in rice blast isolates, which are relatively stable by comparison, suggested that the telomere instability in gray leaf spot isolates could be due to MoTeRs. Analyzing spontaneous alterations in telomere restriction fragment profiles of asexual progeny revealed that MoTeRs were involved. Expansion and contraction of MoTeR arrays were observed and account for some telomere restriction profile changes. New telomere formation in asexual progeny followed by MoTeR addition was also observed. Based on this evidence, MoTeRs are largely responsible for the high variability of telomere restriction profiles observed in GLS isolates.
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