This thesis contributes to the knowledge of the species diversity of the Crenicichla lacustris sp. group in the La Plata River basin with description of three new species. Speciation mechanisms within two different species flocks from the middle Paraná/Iguazu and Uruguay Rivers were studied with a phylogenomic approach applying a novel genotyping method based on a Double-Digest Restriction site Adjacent DNA (ddRAD) sequencing. Our results support a repeated origin of morphological species being evolved several times sympatrically and independently in different drainages. A considerable role of hybridization/introgression as an evolutionary force was also proposed. The thesis further uncovers biogeographic aspects of the southern part of Brazilian shield and adjacent coastal rivers.

Made available in DSpace on 2016-09-27T13:40:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-11-04. Added 1 bitstream(s) on 2016-09-27T13:45:09Z : No. of bitstreams: 1 000870647.pdf: 1368263 bytes, checksum: dbbed6b733deb8dc0c8f5c1073fd25c8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Taenia saginata representa uma ameaça à segurança alimentar e à saúde pública devido à infecção pela ingestão de carne mal cozida e contaminada. Esta zoonose está amplamente distribuída, afetando humanos, os hospedeiros definitivos, e bovinos, hospedeiros intermediários. Além disto, a cisticercose bovina é responsável por perdas econômicas significativas devido à condenação de carcaças infectadas. A estratégia fundamental para o controle do complexo teníase-cisticercose consiste em interromper o ciclo evolutivo do parasita, evitando assim a infecção nos animais e no homem. Assim, a principal medida praticada no Brasil tem sido a inspeção de carcaças durante o abate, a qual é também a forma mais comum de diagnóstico. A insuficiente informação molecular de T. saginata tem dificultado o avanço das pesquisas para o aprimoramento de testes diagnósticos, o desenvolvimento de vacinas e a identificação de novas drogas para tratamento. Com o intuito de adquirir informação sobre o estágio de desenvolvimento metacestóide do parasita, foi utilizada a tecnologia de RNAseq para a montagem do transcriptoma de metacestóide de T. saginata. Estes dados serão úteis para estudos futuros envolvendo triagem para diagnóstico e marcadores imunoprofiláticos para a cisticercose bovina / Taenia saginata represents a threat to food security and public health in consequence of human infection by ingestion of contaminated undercooked meat. This zoonosis is worldwide distributed, affecting human, definitive host, and bovine, intermediate host. Besides, bovine cysticercosis is responsible for significant economic losses due to the condemnation of infected carcasses. The main strategy to control taeniasis-cysticercosis complex consists of interrupting the parasite's biological cycle, thus preventing human and animal infection. Therefore, in Brasil the main control measure has been the carcass inspection during the slaughter, which is also the most common diagnostic practice. Insufficient T. saginata molecular information makes difficult consistent advances to the improvement of diagnostic tests, vaccine development and the identification of new drugs for treatment. In order to gain insights about the parasite's metacestode developmental stage, RNAseq technology was used to assemble the whole transcriptome of a T. saginata metacestode. These data will also be useful for the next generation screening studies of diagnostic and immunoprophylatic markers for bovine cysticercosis

Resumo: Taenia saginata representa uma ameaça à segurança alimentar e à saúde pública devido à infecção pela ingestão de carne mal cozida e contaminada. Esta zoonose está amplamente distribuída, afetando humanos, os hospedeiros definitivos, e bovinos, hospedeiros intermediários. Além disto, a cisticercose bovina é responsável por perdas econômicas significativas devido à condenação de carcaças infectadas. A estratégia fundamental para o controle do complexo teníase-cisticercose consiste em interromper o ciclo evolutivo do parasita, evitando assim a infecção nos animais e no homem. Assim, a principal medida praticada no Brasil tem sido a inspeção de carcaças durante o abate, a qual é também a forma mais comum de diagnóstico. A insuficiente informação molecular de T. saginata tem dificultado o avanço das pesquisas para o aprimoramento de testes diagnósticos, o desenvolvimento de vacinas e a identificação de novas drogas para tratamento. Com o intuito de adquirir informação sobre o estágio de desenvolvimento metacestóide do parasita, foi utilizada a tecnologia de RNAseq para a montagem do transcriptoma de metacestóide de T. saginata. Estes dados serão úteis para estudos futuros envolvendo triagem para diagnóstico e marcadores imunoprofiláticos para a cisticercose bovina / Abstract:Taenia saginata represents a threat to food security and public health in consequence of human infection by ingestion of contaminated undercooked meat. This zoonosis is worldwide distributed, affecting human, definitive host, and bovine, intermediate host. Besides, bovine cysticercosis is responsible for significant economic losses due to the condemnation of infected carcasses. The main strategy to control taeniasis-cysticercosis complex consists of interrupting the parasite's biological cycle, thus preventing human and animal infection. Therefore, in Brasil the main control measure has been the carcass inspection during the slaughter, which is also the most common diagnostic practice. Insufficient T. saginata molecular information makes difficult consistent advances to the improvement of diagnostic tests, vaccine development and the identification of new drugs for treatment. In order to gain insights about the parasite's metacestode developmental stage, RNAseq technology was used to assemble the whole transcriptome of a T. saginata metacestode. These data will also be useful for the next generation screening studies of diagnostic and immunoprophylatic markers for bovine cysticercosis / Orientador:Cáris Maroni Nunes / Banca:Adam Taiti Harth Utsunomiya / Banca:Flávia Lombardi Lopes / Banca:Guilherme de Paula Nogueira / Banca: Daniel Guariz Pinheiro / Banca:Marcelo Vasconcelos Meireles / Doutor

Les éléments transposables (ETs) sont des composants ubiquitaires des génomes eucaryotes, parfois prépondérants chez les plantes. Ce sont des séquences mobiles, potentiellement mutagènes, reconnues comme des acteurs de l’évolution des génomes. Cependant, la plupart des ETs sont aujourd’hui inactifs car réprimés par des mécanismes épigénétiques très efficaces. Néanmoins, ces derniers peuvent être relâchés par des stress, conduisant à la réactivation d’ETs. De tels stress sont-ils suffisants pour activer la transposition dans les populations naturelles? L’application répétée d’un stress peut-elle expliquer les pics d’activité transpositionnelle qui ont eu lieu en conditions naturelles? De récents travaux chez un mutant d’Arabidopsis thaliana, affecté dans une voie de répression d’ETs, le RdDM (RNA-directed DNA Methylation), ont démontré qu’un stress thermique conduisait à la réactivation transpositionnelle d’un ET. Mes travaux de thèse portent sur l’étude de riz sauvage et d’un mutant non décrit, affecté dans le RdDM, cultivés en conditions normales ou de stress thermique sur plusieurs générations. Les objectifs de mes travaux ont été de déterminer (1) l’impact de la mutation sur les différentes étapes d’activation rétrotranspositionnelle et (2) l’activation rétrotranspositionnelle en réponse à un stress thermique. Une part importante de ce travail a été consacrée au développement et à la comparaison de méthodes d’identification des mouvements d’ETs et différentes approches « omiques » ont été utilisées. La réactivation de 5 ETs dans les plantes mutantes, dont la mobilité n’avait pas encore été observée, suggère que la voie RdDM est impliquée dans le contrôle de leur répression. De plus, nos résultats confirment que les ETs ne sont pas tous réprimés par les mêmes voies de régulation. / Transposable elements (TEs) are ubiquitous among eukaryotic genomes sometimes overriding in plants. Due to their ability to replicate and transpose, they are potentially mutagenic and recognized as actors of genome evolution. However, the analysis of the transpositional activity of TEs in different plant species have shown that most of them are maintained in a transcriptionally inactive state through powerful and specific epigenetic mechanisms. These silencing processes can nevertheless be allievated under stress conditions, leading to TE reactivation. Are these stress sufficient to activate transposition in natural populations? Are repeated heat stress able to trigger transposition and therefore lead to bursts of transposition? In recent reports, reactivation of retrotransposons has been shown in Arabidopsis thaliana mutants impaired in the RdDM pathway (RNA-directed DNA Methylation) and submitted to heat stress. My PhD works reports the study of of a wild rice and a new rice mutant, affected in the RdDM, cultivated under optimal or heat stress conditions over generations. Here, we propose to determine (1) the impact of the mutation at the different levels leading to the retrotranspositional activation and (2) the retrotranspositional activity in response to heat stress. An important part of this work has been devoted to the development and the comparison of different methods to identify TE movements, and different -omics approaches have been used. The reactivation of 5 new TEs in mutants, suggests that the RdDM pathway is involved in the control of the repression of these TEs. Furthermore, our result confirm that all TEs are not regulated through the same pathways but are under the control of different lock.