Foram submetidos à análise molecular, 15 isolados do vírus da bronquite infecciosa (VBI) obtidos durante o período de 1988 a 2000, de surtos à campo da Bronquite Infecciosa (BI), em aves de corte ou de postura das regiões Sul e Sudeste do Brasil. Os resultados obtidos da análise filogenética das sequências parciais dos genes da glicoproteína de espícula (S1) e da nucleoproteína (N) evidenciaram que a maior parte dos isolados estão distribuídos em dois grandes grupos; o primeiro deles mais estreitamente relacionado às estirpes do genótipo Massachusetts e o segundo constituído apenas por isolados brasileiros autóctones com uma grande diversidade em relação às estirpes ou isolados do grupo Massachusetts e de outros países ou continentes. Os sítios polimórficos mais importantes formaram-se em locais específicos e de maneira agrupada nas sequências dos genes S1 ou N e predominam em regiões codificadoras das cadeias polipeptídicas S1 e N que configuram sítios estruturais e antigênicos importantes envolvidos, na expressão de propriedades biológicas relevantes. / Fifteen Brazilian field isolates of infectious bronchitis virus (IBV); were recovered, between 1988 and 2000, from commercial broiler or layer flocks located in South and Southeast Brazilian regions. Molecular and phylogenetic analysis of partial sequences of 5\'-proximal of S1 gene and 3\'-terminus of N gene from these IBV isolates, identified two main groups; the Massachusetts group and a Brazilian indigenous group, which presenting a high diversity regarding the first group or other IBV strains from different countries and continents. The major polymorphic sites are arranged in clusters and predominate in the regions of S1 and N genes which code for relevant structural and antigenic sites responsible for the expression of important biological properties.

Made available in DSpace on 2014-06-11T19:27:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-14Bitstream added on 2014-06-13T20:35:46Z : No. of bitstreams: 1 oliveira_ap_me_jabo.pdf: 460448 bytes, checksum: eeb8cefed995b5624ebdb1b544ded04b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A glicoproteína de superfície (8) do vírus da bronquite infecciosa (VBI) em aves; é um alvo antigênico importante para a indução de imunidade e como antígeno utilizado no imunodiagnóstico da infecção causada por este vírus. Nesse estudo, a forma recombinante da subunidade 81 da glicoproteína 8 da estirpe M41 do VBI foi clonada e expressa como proteína de fusão contendo uma cauda de poli-histidina e o epítopo V-5 em células da levedura Saccharomyces cerevisiae. O gene codificador dessa proteína foi amplificado a partir do RNA genômico da estirpe M41 do VBI, por meio das técnicas da reação de transcrição reversa (RT) e da reação da polimerase em cadeia (PCR). Foi amplificada toda a seqüência codificadora de interesse e fossem geradas extremidades compatíveis com a inserção no vetor pYE82.1N5-His-TOPO. Este vetor foi usado na transformação de leveduras, tendo sido obtidos os clones transformantes específicos portadores do inserto gênico. A expressão da proteína de fusão foi então induzida, em células de S. cerevisiae, sendo produzida a proteína recombinante 81 de fusão com peso molecular 95 kDa. Essa proteína apresentou com uma elevada reatividade cruzada para a proteína 8 do próprio vírus, tal como demonstraram os resultados das análises pelo Western blotting e ELl8A. Essa proteína de fusão foi, devido à presença da cauda de poli¬histidina, prontamente purificada por cromatografia de afinidade em coluna de níquel ¬agarose e, posteriormente utilizada com sucesso no desenvolvimento de um método indireto de ELl8A para a detecção de anticorpos específicos de galinhas infectadas com o VBI. / The surface glycoprotein of infectious bronchitis virus (IBV) is a important antigenic target for the induction of immunity and as antigen in the immunodiagnosis of infection caused by this virus. In this study, the gene of 51 glycoprotein of M41 strain of the IBV was cloned and expressed as a fusion protein containing a poly-histidine and epitope V-5 tags in the yeast cells of Saccharomyces cerevisiae. The 51 gene was amplified from genomic RNA of the M41 strain of VBI, by reverse transcription (RT) and polymerase chain reaction (PCR). The entire coding sequence of 51 gene was amplified and inserted in the vector pYE52.1N5-His-TOPO. This construct was used for transforming yeast cells, and to obtain specific clones carrying the inserted gene. The expression of the fusion protein was induced in transformed cells of S. cerevisiae, and a recombinant 51 protein was produced with a molecular weight of 95 kDa. A high cross¬reactivity with the original 51 protein from the virus was detected by Western blotting and ELl5A. The presence of the poly-histidine tail in the fusion recombinant protein favored their prompt purification by affinity chromatography in a column of nickel¬sepharose. This recombinant 51 protein was successfully used in the development of an indirect method of ELl5A for the detection of specific anti-IBV antibodies in chickens experimentally infected or vaccinated with this virus.

No description available.

In practice, graphs often occur as perturbed product structures, so-called approximate graph products. The practical application of the well-known prime factorization algorithms is therefore limited, since most graphs are prime, although they can have a product-like structure. This work is concerned with the strong graph product. Since strong product graphs G contain subgraphs that are itself products of subgraphs of the underlying factors of G, we follow the idea to develop local approaches that cover a graph by factorizable patches and then use this information to derive the global factors. First, we investigate the local structure of strong product graphs and introduce the backbone B(G) of a graph G and the so-called S1-condition. Both concepts play a central role for determining the prime factors of a strong product graph in a unique way. Then, we discuss several graph classes, in detail, NICE, CHIC and locally unrefined graphs. For each class we construct local, quasi-linear time prime factorization algorithms. Combining these results, we then derive a new local prime factorization algorithm for all graphs. Finally, we discuss approximate graph products. We use the new local factorization algorithm to derive a method for the recognition of approximate graph products. Furthermore, we evaluate the performance of this algorithm on a sample of approximate graph products.

Submitted by CAREN PAVANI null (caren_pavani@hotmail.com) on 2017-08-29T17:29:24Z No. of bitstreams: 1 Dissertacao-POS-Caren-DEFINITIVO-V-2-HJM-AGO-23-17.pdf: 1281724 bytes, checksum: 16544949d05b1aee20711a16abcbfdac (MD5) / Rejected by Luiz Galeffi (luizgaleffi@gmail.com), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: A lombada de seu trabalho só é necessária na versão impressa, para encadernação. Por favor, exclua a lombada da versão digital. Corrija estas informações e realize uma nova submissão contendo o arquivo correto. Agradecemos a compreensão. on 2017-08-29T18:44:21Z (GMT) / Submitted by CAREN PAVANI null (caren_pavani@hotmail.com) on 2017-08-29T18:51:55Z No. of bitstreams: 1 Dissertacao-POS-Caren-DEFINITIVO-V-2-HJM-AGO-23-17.pdf: 1278516 bytes, checksum: 04ce7b2fc7a143ce39b6187b81ee676f (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-29T18:59:47Z (GMT) No. of bitstreams: 1 pavani_c_me_jabo.pdf: 1278516 bytes, checksum: 04ce7b2fc7a143ce39b6187b81ee676f (MD5) / Made available in DSpace on 2017-08-29T18:59:47Z (GMT). No. of bitstreams: 1 pavani_c_me_jabo.pdf: 1278516 bytes, checksum: 04ce7b2fc7a143ce39b6187b81ee676f (MD5) Previous issue date: 2017-08-02 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Em plantéis avícolas, é frequente a ocorrência de doenças infecciosas respiratórias e dentre estas, destaca-se a Bronquite Infecciosa (BI), uma doença aguda e altamente contagiosa de aves. A BI é causada pelo vírus da bronquite infecciosa (VBI), cujo processo infeccioso geralmente provoca perdas econômicas significativas para as criações avícolas. A extensa variação genética, especialmente nas regiões hipervariáveis (HVRs) do gene S1, é uma das principais características da evolução do VBI, e resulta no surgimento de diversas variantes, que requerem um diagnóstico molecular que inclua a detecção dessas novas estirpes, como o genótipo brasileiro (BR-VBI), pois a detecção e identificação do agente etiológico são essenciais para o controle dessa enfermidade. Para tanto, é necessário que os métodos de diagnóstico empregados sejam sensíveis, específicos e de baixo custo. Foi então desenvolvida e avaliada neste estudo uma técnica de Nested-RT-PCR (BR-Nested-RT-PCR) utilizando um conjunto de oligonucleotídeos iniciadores desenvolvido dentro da região HVR3 do gene S1 de estirpes variantes brasileiras do VBI para a detecção e identificação de linhagens do genótipo brasileiro do VBI presentes em amostras biológicas de aves e comparada com a Nested-RT-PCR universal, utilizando oligonucleotídeos iniciadores universais para a mesma região do gene S1. Os resultados demonstraram que a técnica BR-Nested-RT-PCR apresentou uma elevada sensibilidade na detecção de estirpes do genótipo BR-I do VBI e não gerou produtos amplificados a partir de amostras de vírus heterólogos testados (vírus da doença de Newcastle, metapneumovírus aviário, reovírus e vírus da doença de gumboro), nem de estirpes do VBI classificadas em outros genótipos.). Ademais, quando foram comparadas as técnicas BR-Nested-RT-PCR com a técnica universal de Nested-RT-PCR foram obtidas boa concordância (k = 0,67), sensibilidade relativa de 85,4% e especificidade relativa de 81,6% para a detecção direta e identificação de estirpes do genótipo BR em amostras de campo. Em conclusão, a técnica de BR-Nested-RT-PCR desenvolvida no presente estudo, oferece uma opção de menor custo e menor complexidade do que a técnica de RT-PCR em tempo real para detectar e diferenciar estirpes do genótipo BR-I do VBI, sem comprometer a especificidade ou a sensibilidade, tendo, assim, o potencial de viabilizar a adoção de meios mais efetivos para o diagnóstico direto de estirpes do genótipo BR-I do VBI em amostras colhidas de aves mantidas em criações comerciais. / Infectious bronchitis (IB) is an acute and highly contagious disease of birds. IB is caused by infectious bronchitis virus (IBV), which usually results in significant economic losses for poultry farms. The extensive genetic variation, especially in the hypervariable regions (HVRs) of the S1 gene, is one of the main characteristics of the evolution of IBV, and results in the appearance of several variants that require a molecular diagnosis which includes the detection of these new strains, such as Brazilian I genotype (BR-I), since the detection and identification of the causative agent are essential for the control of the disease. Therefore, the diagnostic methods used must be sensitive, specific and inexpensive. A Nested-RT-PCR (BR-Nested-RT-PCR) technique was developed and evaluated in this study using a set of primers designed for the HVR3 region of the S1 gene for the detection and identification of Brazilian genotype strains of IBV present in biological samples from birds and compared with universal Nested-RT-PCR using universal primers for the same region of the S1 gene. The results demonstrated that the BR-Nested-RT-PCR technique had a high sensitivity to detect IBV strains from BR-I genotype and did not generate amplified products from heterologous virus samples tested (Newcastle disease virus, avian metapneumovirus, Reovirus and Gumboro disease virus), neither from IBV strains of other genotypes. In addition, the comparison between BR-Nested-RT-PCR techniques with the universal Nested-RT-PCR technique revealed good agreement (k = 0.67), relative sensitivity of 85.4% and relative specificity of 81.6 % for the direct detection and identification of BR-I genotype strains in field samples. In conclusion, the BR-Nested-RT-PCR technique developed in the present study offers a lower cost and less complex option than the real-time RT-PCR technique to detect and differentiate strains of the BR-I genotype of IBV without compromising specificity or sensitivity, and has the potential to provide a more effective mean for the direct diagnosis of BR-I IBV strains in samples collected from birds reared in commercial flocks. / CNPq: 132790/2015-7

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-11-29T18:59:55Z No. of bitstreams: 2 Dissertação - Aurilene Santos Oliveira 2013.pdf: 2646271 bytes, checksum: aa9174ef69bab8b407a57a5e249619fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-11-30T15:36:35Z (GMT) No. of bitstreams: 2 Dissertação - Aurilene Santos Oliveira 2013.pdf: 2646271 bytes, checksum: aa9174ef69bab8b407a57a5e249619fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-11-30T15:36:35Z (GMT). No. of bitstreams: 2 Dissertação - Aurilene Santos Oliveira 2013.pdf: 2646271 bytes, checksum: aa9174ef69bab8b407a57a5e249619fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2013-08-23 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / With the possibility of planting corn in two seasons (normal and late crops) the Brazil has increased the total corn production, but it is necessary to develop new hybrids and varieties aiming to increase productivity in both planting dates, to attend increasing demand for this commodity. The objectives of the present work were directed for the study the genetic variability, evaluate the yield potential and estimate inbreeding depression in three semiexotic populations of maize, for purposes of recurrent selection. The field evaluation was in two experiments: Jataí (GO) and Anhembi (SP). The first experiment was represented by half-sib families, which were evaluated in randomized complete blocks with three replications with plots of 4m (0.90 m spacing) with 20 plants. The second experiment included half-sib and S1 families in two replications with plots of 3m (0,90 m spacing) with 15 plants. The following primary characters were evaluated: AP - plant height (cm), AE - ear height (cm), DE – ear diameter (cm), EC - ear length (cm), NP - number of plants, NE – ear of number, PE - ear weight (g parcela-1 ), PG – total grain weight (g parcela-1 ), PE4 - four ear weight, PG4 - four ear grain weight , NR -tassel branch number, CP - tassel length (cm), AD - evaluation of foliar disease and ACE - evaluation of corn stunt complex. The semiexótic populations CRE had an excellent pattern of genetic variability and a good productive potential, presenting an average yield of 70% compared to checks. Within the three populations it was observed differences of families in relation to resistance to corn stunt, indicating that selection for this trait can fairly effective. / RESUMO: Com a possibilidade do plantio de milho em duas épocas (safra e safrinha) o Brasil tem elevado a produção total de milho, porém é necessário desenvolver novos híbridos e variedades visando o aumento da produtividade em ambas as épocas de plantio, para atender a crescente demanda pelo grão de milho. Os objetivos do presente trabalho se dirigem ao estudo da variabilidade genética, avaliar o potencial produtivo, estimar a depressão por endogamia e avaliar o comportamento quanto a resistência ao complexo de enfezamento em três populações semiexóticas de milho, para fins de seleção recorrente. Foram instalados dois experimentos: Jataí (GO) e Anhembi (SP). No primeiro experimento foram utilizadas famílias de meios-irmãos, que foram avaliadas em experimentos delineados em blocos casualizados com três repetições de parcelas de 4m (espaçamento de 0,90m) com 20 plantas. No segundo experimento foram utilizadas famílias de meios-irmãos e famílias S1 com duas repetições de parcelas de 3m (espaçamento de 0,90m) com 15 plantas. Foram avaliados os seguintes caracteres: AP – altura de planta (cm), AE – altura de espiga (cm), DE – diâmetro de espiga (cm), CE – comprimento de espiga (cm), NP – número de plantas, NE – número de espiga, PE – peso de espiga (g.parcela-1 ), PG – peso de grãos (g.parcela-1 ), PE4 – peso de quatro espiga, PG4 – peso de grãos de quatro espiga, NR – número de ramificações do pendão, CP – comprimento de pendão (cm), AD – avaliação de doença foliar e ACE – avaliação do complexo de enfezamento. As populações semiexóticas apresentaram um excelente padrão de variabilidade genética e um bom potencial produtivo, apresentando em média produtividade de 70% em relação à testemunha. Dentro das três populações observou-se um comportamento diferente das famílias em relação à resistência ao complexo de enfezamento, indicando que seleções para este caráter nas populações pode trazer resultados satisfatórios.

La traduction est une étape clef de l’expression des gènes, et mon travail a consisté à étudier l’implication de la protéine ribosomique S1 d’Escherichia coli dans l’initiation de la traduction des ARNm structurés. Mes résultats montrent que 1) S1 est requise pour la formation du complexe d’initiation des ARNm portant une séquence SD faible et/ou des structures stables, 2) elle est dotée d’une activité chaperonne, débobinant les ARNm afin de les placer dans le canal de décodage ; et 3) le ribosome favorise son action. Par la suite, j’ai montré un rôle inattendu de S1 dans la régulation post-transcriptionnelle médiée par les ARNnc. En effet, la dégradation rapide de l’ARNm sodB, induite par l’ARNnc RyhB en absence de fer, est perdue dans une souche dont l’extrémité C-terminale de S1 a été supprimée, montrant ainsi un lien fonctionnel entre S1 et le dégradosome. Ainsi, S1 exerce de multiples fonctions qui se placent au carrefour de la traduction et de la régulation de l’expression des gènes / The translation is a key step for the gene expression, and the aim of my PhD was to analyze the involvment of Escherichia coli ribosomal protein S1 in the translation initiation of structured mRNAs.My results show that 1) S1 is required for the establishment of the active translation initiation complex involving mRNAs with a weak SD sequence and/or stable structures, 2) S1 has a RNA chaperone activity, unwinding the mRNA in order to accommodate it in the decoding channel, and 3) the ribosome promotes its activity.In the second part of my thesis, I unexpectedly showed that S1 is involved in the ncRNAmediated regulation. Indeed, the fast degradation of sodB mRNA, induced by RyhB ncRNA under iron depletion, is impaired in a strain depleted of the C-terminal part of S1 protein, thus highlighting a functional link between S1 and the degradosome.All in one, my results show that S1 is endowed with multiple functions, at the cross-road between translation and regulation of gene expression.

O presente trabalho estuda a variação do diâmetro inicial e diâmetro final de um furo puncionado feito em uma chapa de aço ASTM A-36 com 12,7 mm de espessura. São propostas três geometrias diferentes de punção fabricados em aço AISI D2 e AISI S1 com diâmetro inicial 20 mm e final 22 mm. Os punções foram fabricados para realizarem o processo de puncionamento e brochamento com penetrações de avanço (asf) de 0,2 mm, 0,5 mm e 1 mm. O objetivo principal é reduzir a conicidade dos furos puncionados atualmente através do método convencional. As folgas entre punção e matriz (w) utilizadas foram de 3,1%, 7,8% e 15,7% da espessura da chapa de testes respectivamente. Para avaliação do desempenho de cada ferramenta, todos os furos puncionados foram medidos e tabelados. Entre os resultados encontrados, constatou-se que os punções com brochamento apresentam melhores valores que os convencionais em todos parâmetros analisados. As regiões de cisalhamento (Zc) e região de ruptura abrupta (Zr) também sofreram influência direta em função da geometria utilizada. / The present work studies the variation of the initial diameter and final diameter of a punched hole made in an ASTM A-36 steel sheet with 12.7 mm of thickness. Three different punches geometries are proposed and manufactured from AISI D2 and AISI S1 steel with initial diameter 20 mm and final diameter 22 mm. The punches were manufactured to carry out the punching and broaching process with feed penetrations (asf) of 0.2 mm, 0.5 mm and 1 mm. The main objective is to reduce the conicity of the punched holes currently through the conventional method. The clearance between punch and die (w) used were 3.1%, 7.8% and 15.7% of the thickness of the test plate respectively. To evaluate the performance of each tool, all punched holes were measured and tabulated. Among the results, it was observed that the punches with a broaching showed better values than the conventional ones in all analyzed parameters. The regions of shear (Zc) and region of abrupt rupture (Zr) also had a direct influence in function of the geometry used.

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide. Current therapeutic approaches for HCC including surgical resection and trans-arterial embolization (TAE) remain largely ineffective, underscoring the need for development of novel therapeutic strategies. Because HCC is high vascularized, continuous administration angiogenesis inhibitor using gene therapy approach may facilitate long-term blockade tumor vasculature, thereby perturbing the growth of HCC. Vasostatin 112 (VS112) encodes an alternatively spliced fragment of angiogenesis inhibitor vasostatin, which encompasses residues 1-64 and 133-180 of calreticulin. In this study, recombinant adenovirus encoding VS112 (Ad-VS112) was generated to evaluate its potential for suppression of orthotopic Novikoff hepatoma in syngenic Sprague-Dawley (SD) rats. Adenovirus-mediated VS112 overexpression significantly inhibited the migration and tube formation of endothelial cells, indicating the anti-angiogenic potency of VS112 gene delivery. However, VS112 overexpression had no influence on the viability of N1-S1 Novikoff hepatoma cells. To investigate the prophylactic effect of VS112 expression on hepatoma growth, N1-S1 cells were infected with Ad-VS112 or adenovirus encoding green fluorescent protein (Ad-GFP) then implanted into the liver of SD rats. After 14 days, rats implanted with VS112-expressing showed significantly reduced incidence and size of hepatoma compared with those implanted with Ad-GFP-infected cells. To investigate the therapeutic efficacy of VS112 gene delivery, the SD rats were implanted with N1-S1 cells on day 0, treated with adenovirus vectors (2 x 1010 plaques forming units) via intravenous route on day 1, then sacrificed on day 14 to monitor hepatoma growth. By measuring tumor weight, it was found that Ad-VS112-treated rats exhibited significantly decreased tumor burden compared with control groups, which was in accordance with their lower serum GOT level. Histological analysis revealed a significant reduction of vWF-positive blood vessels in Ad-VS112-treated tumors, which was accompanied with a decrease in Ki-67-positive proliferating cells and an increase in TUNEL-positive apoptotic cells. Moreover, the expression of pro-inflammatory nuclear factor kappa B (NF£eB) and cyclooxgenase II (COXII) was also effectively attenuated in Ad-VS112-treated hepatoma. In conclusion, prior or post VS112 gene delivery potently suppresses the growth of orthotopic hepatoma,thereby holding promises for future treatment of HCC.

Dans cette thèse, nous établissons un théorème de rigidité topologique pour une large classe de sous-groupes du groupe de difféomorphismes analytiques réels préservant l'orien- tation du cercle Diff (S1). En effet, les objets principaux étudiés dans cette thèse sont les sous-groupes localement C 2-non-discrets de type fini de Diff (S1). Dans le premier Chapitre, on donne des rappels sur la relation entre la théorie de la mesure et les systèmes dynamiques et on donne aussi des rappels sur les définitions et les propriétés des espaces hyperboliques, des groupes hyperboliques et des leurs bords. Le deuxième Chapitre contient des définitions précises pour la plupart des notions pertinentes pour cette thèse, revisite les résultats concernant la théorie de Shcherbakov- Nakai sous une forme adaptée à nos besoins et fournit une description des dynamiques topologiques associées au sous-groupe localement C 2-non-discret de Diff (S1). Le troisième Chapitre est consacré à la preuve du Théorème A "le théorème de rigidité topologique". Dans la première section de ce chapitre, on démontre le Théorème A dans divers cas particuliers, dont le cas où le groupe a une orbite finie et le cas où le groupe est résoluble mais non-abélien. Il restera alors démontrer le Théorème A dans le cas dit "générique" et cela sera l'objet du restant de ce chapitre. Dans la deuxième section de ce chapitre, nous construisons une suite de difféomorphismes de G1 convergeant vers l'identité dans C 2-topologie sur l'intervalle I C S1. Dans la dernière section de ce chapitre, nous allons démontrer le Théorème A modulo la Proposition 3.3.3. En effet, le Théorème 3.3.1 sera prouvé et ce théorème constitue un énoncé plus forte que celui du Théorème A. L'énoncé principal du quatrième Chapitre est le Théorème 4.2.1. La démonstration du Théorème 4.2.1 est une combinaison des faits standards sur les groupes hyperboliques avec l'éxistence d'une mesure µ sur G1 donnant lieu à une mesure stationnaire absolu- ment continue. Ce théorème entraînera la démonstration du Théorème B. Finalement, l'Annexe contient une réponse partielle dans la catégorie analytique à une question posée dans [De]. L'annexe se termine ensuite par un résumé du rôle joué par l'hypothèse de régularité (C) dans cette thèse. / In this thesis we establish a topological rigidity theorem for a large class of subgroups of the group Diff (S1) consisting of (orientation-preserving) real analytic diffeomorphisms of the circle S1. Indeed, the primary object studied in this thesis are finitely generated, locally C 2-non-discrete subgroups of Diff (S1). In the first Chapter, we briefly recall several basic facts in the relation between measure theory and dynamical systems and recall the definitions and basic properties of hyperbolic spaces, hyperbolic groups and their boundaries. The second Chapter contains accurate definitions for most of the notions relevant for this thesis, revisits results related to Shcherbakov-Nakai theory in a form adapted to our needs and provides a description of the topological dynamics associated with a locally C 2-non-discrete subgroup of Diff (S1). The third Chapter is devoted to proving Theorem A "topological rigidity theorem". In the first section of this chapter, we prove Theorem A in various special cases, including the case where the group has a finite orbit as well as the case in which the group is solvable but non-abelian. It will then prove Theorem A in the case called "generic" and this will be the subject of the remainder of this chapter. In the second section of this chapter, we construct an explicit sequence of diffeomorphisms in G1 converging to the identity in the C 2-topology on the interval I C S1. In the last section of this chapter, we shall prove Theorem A modulo Proposition 3.3.3. In fact, Theorem 3.3.1 will be proved and this theorem provides a statement fairly stronger than what is strictly needed to derive Theorem A. The main statement in the fourth Chapter is Theorem 4.2.1. The proof of The- orem 4.2.1 is combined standard facts about hyperbolic groups with the existence of a measure µ on G1 giving rise to an absolutely continuous stationary measure. This theorem will lead to the proof of Theorem B. In the end, the Appendix contains a partial answer in the analytic category to a question raised in [De]. The appendix then ends with a summary of the role played by the regularity assumption (C) in this thesis.