The conserved Metazoan protein β-catenin has important functions in both Wnt signalling and Cadherin-mediated adhesion. Tight regulation of β-catenin levels and location within cells is vital for the correct control of homeostasis, differentiation, morphogenesis and cell migration in developing and adult Metazoa. Misregulation of β- catenin leads to cells with altered proliferative and migratory properties and can lead to cancer. The Metazoan proteins BCL9 and Pygopus are important for the regulation of β- catenin and show different requirements in different organisms. β-catenin binds to BCL9, which binds to Pygopus. These interactions are thought to be involved in activation of Wnt signalling-dependent transcription, localisation of β-catenin and cross-talk between Wnt signalling and Cadherin-mediated adhesion. This thesis describes experiments using the frog Xenopus laevis to characterise the activities of carnosate, a small molecule inhibitor of the β-catenin-BCL9 interaction, and to assess its potential value as a drug for cancer therapy. More generally this thesis describes experiments undertaken towards a better understanding of how β-catenin links Wnt signalling and Cadherin-mediated adhesion and what role BCL9 and Pygopus play in this regard.

Metazoan development is a complex and tightly controlled process that not only requires precise cell fate differentiation, but also demands accurate timing of cell division and precise cell migration. Genetic regulation of cell cycle length throughout metazoans embryogenesis is largely unknown, mainly due to the technical hurdle in quantifying cell division timing during development. Caenorhabditis elegans embryogenesis provides an excellent opportunity to study the genetic regulation of division timing because of its invariant cell lineage and widespread division asynchronies between sister cells. A combination of in toto imaging and automated cell lineaging coupled with high throughput RNAi allows genetic screening of genes involved in regulation of Asynchrony of Division between Sister cells (ADS) or cousin cells. One of the most pronounced asynchronies between cousin cells during C. elegans embryogenesis is a significant elongation of division timing in two endoderm progenitor cells, Ea and Ep (E2), versus their cousins MSa and MSp (MS2) that mainly develop into mesoderm organs. Out of a total of 822 essential and conserved genes that were perturbed by RNAi in our previous genetic screening, 53 genes are found to produce significantly reduction specifically in the E2 cell cycle length (p<0.01). Surprisingly, nearly 70% of the 53 genes are involved in mRNA production or its regulation, indicating a differential requirement of transcription for division timing between E2 and MS2. Reduction in E2 cell cycle length is frequently associated with cell migration defect and gastrulation failure. Furthermore, our systematic data on cell division timings upon perturbation of a large cohort of essential genes provide a valuable source for inferring the function of uncharacterized gene. For example, phenotypical clustering based on cell division timings suggested that an essential gene, gad-1, is likely to be involved in general transcription, which is in agreement with its further functional assays. In summary, a combining of the published data with our own demonstrates that E2 specific cell cycle elongation requires robust and earlier zygotic genome activation (ZGA) during C. elegans embryogenesis. The cell-specific elongation might be important for coordinate fate differentiation, division timing and cell migration of E2 to ensure proper intestine development.

Cloudina foi o primeiro fóssil de um organismo biomineralizado encontrado no final do Ediacarano. Também figuram nesse período Corumbella, Namacalathus, Sinotubulites e Namapoikia entre a biota esquelética. No Grupo Corumbá (MS), em carbonatos e pelitos da Formação Tamengo, ocorrem os fósseis de Cloudina e Corumbella, respectivamente. Este trabalho teve como objetivo analisar questões paleobiológicas referentes ao fóssil esquelético Cloudina, como seu contexto tafonômico, taxonômico e paleoecológico. Análises geoquímicas e de microestrutura foram realizadas para permitir melhor compreensão da esqueletogênese desse fóssil. Para tanto, foram utilizadas técnicas paleométricas, como: Espectroscopia Raman, Energia Dispersiva de Raios-x (EDS), Fluorescência de Raios-x por Energia Dispersiva (EDXRF) e Fluorescência de Raios-x Sincrotron (XRF-SRS) - para as análises de composição química e mineralógica; e Microscopia Eletrônica de Varredura (MEV) e Microtomografia Computadorizada (MicroCT) - para imageamento de microestruturas e feições morfológicas não visíveis na superfície, respectivamente. As análises tafonômicas de orientação revelaram padrões NNE-SSW e NE-SW, assim como WNW-ESSE, sugerindo correntes que variaram desde quase paralelas, até, possivelmente, perpendiculares com relação à linha de costa. As alterações tafonômicas encontradas incluem fragmentação das porções externas da concha, deformação plástica, neomorfismo, dissolução da parede e presença de calcita eodiagenética entre as abas dos funis. Esse contexto tafonômico indica uma deposição por retrabalhamento dos bioclastos e sugere que informações morfológicas, como diâmetro, são alteradas tafonomicamente. A análise biométrica das amostras alóctones indicou bimodalidades para populações estatísticas de Cloudina considerando 1, 2, 3 ou 4 camadas em corte transversal, e conjuntamente com a distribuição de tamanho normal para uma assembleia autóctone sugere uma mistura de populações originais de tamanhos diferentes. Esses resultados trazem implicações para a taxonomia de Cloudina para esses depósitos, definindo C. lucianoi como tafotáxon. A análise da amostra autóctone demonstra a ocorrência de Cloudina com biolaminitos e microfósseis e fortalecem a interpretação de que esse metazoário vivia em habitats associados com microbialitos. A presença de goethita e calcita eodiagenética entre as abas de Cloudina, assim como microesferas silicificadas sugerem a presença de uma matéria orgânica nessas porções externas do organismo que podem estar relacionadas com o desenvolvimento de possíveis biofilmes simbiontes. A posição de vida horizontal verificada para Cloudina na amostra autóctone indica a versatilidade de modo de vida dessa organismo quando comparada a ocorrências de espécimes verticais em outras localidades. Nessa mesma amostra, indivíduos com mudanças na direção de crescimento podem ser resultantes da proximidade com outros espécimes, o que sugere capacidade sensoriais que auxiliariam na ocupação do substrato. Os resultados de MEV demonstraram que geralmente a microestrutura não está preservada, mas em alguns casos pode-se notar microgrânulos de calcita e um padrão reticulado. Conjuntamente com MEV, em análises petrográficas foram observadas duas camadas formando a parede de Cloudina. As análises geoquímicas de EDS e Raman demonstraram a presença de carbono na concha e corroboram trabalhos anteriores que postularam uma concha rica em matéria orgânica. As quantidades de Mg% e MgO% verificadas por EDS caracterizaram os fósseis da Formação Tamengo como de baixo teor de magnésio e fitting de bandas de calcita em espectros Raman fortalecem essa interpretação. Mesmo assim, alterações diagenéticas de estabilização por perda de Mg podem ter ocorrido. Os resultados de XRF-SRS mostraram que não há variação de Sr maior que 1000 ppm entre o fóssil e a rocha, indicando que, pelo menos, a mineralogia da concha não era aragonítica. Sendo assim, o presente trabalho traz novos cenários para a paleobiologia de Cloudina da Fm. Tamengo: Cloudina lucianoi é considerado como tafotáxon pelo contexto tafonômico e análise biométrica, indica ambientes de vida associados com microbialitos e possíveis cianobactérias, relações simbióticas podem ter ocorrido entre esse metazoário e biofilmes, é inferido modo de vida horizontal a sub-horizontal, é sugerido comportamentos de competição por espaço, a esqueletogênese de Cloudina é caracterizada por funis compostos por uma parede com duas camadas, rica em matéria orgânica e com microgrânulos de calcita. / Cloudina was the first fossil of a biomineralized organism found in latest Ediacaran. Also in this period, there was Corumbella, Namacalathus, Sinotubulites and Namapoikia within the skeletal biota. In the Corumbá Group (MS), in carbonates and pelites of Tamengo Formation, occur the fossils of Cloudina and Corumbella, respectively. This work aims to analyze paleobiological questions regarding Cloudina, such as its taphonomical, taxonomical and paleoecological context. Geochemical and microstructural analyses were performed to better understand the skeletogenesis of this fossil. For this, were utilized paleometrical techniques, such: Raman Spectroscopy, Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Fluorescence Synchrotron based (XRF-SRS) - for chemical and mineralogical analyses; and Scanning Electron Microscopy (SEM) and Computerized Microtomography (MicroCT) - for imaging of non-visible surficial microstructures and morphological attributes. The taphonomical analyses of orientation revealed NNE-SSW and NE-SW, as well as WNW-ESSE patterns, indicating currents that varied from almost parallel, to, possibly, perpendicular with relation to the ancient coastline. The taphonomical alterations include fragmentation of the external portions of the flares, plastic deformation, neomorphism, dissolution of the wall and the presence of eodiagenetic calcite between the flares of the funnels. This taphonomical context suggests a deposition by reworking and indicates that morphological information, such as diameter, is taphonomical altered. The biometrical analysis for the allochthonous specimens indicated bimodality for the statistical populations of Cloudina considering one, two, three or four layers in cross section, and together with the normal size distribution for the autochthonous assemblage suggest a mixture of original populations of different sizes. These results bring implications to the taxonomy of Cloudina, defining C. lucianoi as a taphotaxon. The study of the autochthonous assemblage demonstrated the occurrence of Cloudina with biolaminites and microfossils, and strengthens the interpretation that this metazoan lived in habitats associated with microbialites. The presence of goethite and eodiagenetic calcite between the flares of Cloudina, as well as silicified microspheres suggest the presence of organic matter in these external portions of the organism that can be related to de development of possibly symbiotic biofilms. The horizontal life position verified for Cloudina in the autochthonous assemblage together with occurrences in other localities of vertical specimens indicates the versatility of the life modes of this organism. Also in this sample, individuals with changes in the growing direction could be resultant of the proximity with other specimens, suggesting sensorial capacities, which assisted in the occupation of the substrate. SEM results demonstrated that often the microstructure is not preserved, but in some cases can be noted microgranules of calcite and a reticulate pattern. Allied with SEM, in petrographic sections were observed two layers forming the wall of Cloudina. EDS and Raman analysis showed the presence of carbon in the carapace and corroborate previous studies that postulated a shell with high amount of organic matter. Quantities of Mg% and MgO% verified by EDS characterized the fossils as low-magnesian calcites and fitting of calcite bands from Raman spectra strengthen this interpretation. Nevertheless, diagenetical alterations of stabilization by loss of Mg could have occurred. The results from XRF-SRS showed that there is no great variation in the Sr content between the fossil and the rock matrix, indicating that the mineralogy was not aragonitic. Thus, this work brings new scenarios for the paleobiology of Cloudina from the Tamengo Fm: Cloudina lucianoi is considered as a taphotaxon by the taphonomical and biometrical results, indicates habitats associated with microbialites and possible cyanobacteria, symbiotic relations could have occurred between this metazoan and biofilms, is inferred a horizontal to sub-horizontal life position and behaviors for space competition, the skeletogenesis of Cloudina is characterized by funnels composed of a wall with two layers, rich in organic matter and with microgranules of calcite.

Cloudina foi o primeiro fóssil de um organismo biomineralizado encontrado no final do Ediacarano. Também figuram nesse período Corumbella, Namacalathus, Sinotubulites e Namapoikia entre a biota esquelética. No Grupo Corumbá (MS), em carbonatos e pelitos da Formação Tamengo, ocorrem os fósseis de Cloudina e Corumbella, respectivamente. Este trabalho teve como objetivo analisar questões paleobiológicas referentes ao fóssil esquelético Cloudina, como seu contexto tafonômico, taxonômico e paleoecológico. Análises geoquímicas e de microestrutura foram realizadas para permitir melhor compreensão da esqueletogênese desse fóssil. Para tanto, foram utilizadas técnicas paleométricas, como: Espectroscopia Raman, Energia Dispersiva de Raios-x (EDS), Fluorescência de Raios-x por Energia Dispersiva (EDXRF) e Fluorescência de Raios-x Sincrotron (XRF-SRS) - para as análises de composição química e mineralógica; e Microscopia Eletrônica de Varredura (MEV) e Microtomografia Computadorizada (MicroCT) - para imageamento de microestruturas e feições morfológicas não visíveis na superfície, respectivamente. As análises tafonômicas de orientação revelaram padrões NNE-SSW e NE-SW, assim como WNW-ESSE, sugerindo correntes que variaram desde quase paralelas, até, possivelmente, perpendiculares com relação à linha de costa. As alterações tafonômicas encontradas incluem fragmentação das porções externas da concha, deformação plástica, neomorfismo, dissolução da parede e presença de calcita eodiagenética entre as abas dos funis. Esse contexto tafonômico indica uma deposição por retrabalhamento dos bioclastos e sugere que informações morfológicas, como diâmetro, são alteradas tafonomicamente. A análise biométrica das amostras alóctones indicou bimodalidades para populações estatísticas de Cloudina considerando 1, 2, 3 ou 4 camadas em corte transversal, e conjuntamente com a distribuição de tamanho normal para uma assembleia autóctone sugere uma mistura de populações originais de tamanhos diferentes. Esses resultados trazem implicações para a taxonomia de Cloudina para esses depósitos, definindo C. lucianoi como tafotáxon. A análise da amostra autóctone demonstra a ocorrência de Cloudina com biolaminitos e microfósseis e fortalecem a interpretação de que esse metazoário vivia em habitats associados com microbialitos. A presença de goethita e calcita eodiagenética entre as abas de Cloudina, assim como microesferas silicificadas sugerem a presença de uma matéria orgânica nessas porções externas do organismo que podem estar relacionadas com o desenvolvimento de possíveis biofilmes simbiontes. A posição de vida horizontal verificada para Cloudina na amostra autóctone indica a versatilidade de modo de vida dessa organismo quando comparada a ocorrências de espécimes verticais em outras localidades. Nessa mesma amostra, indivíduos com mudanças na direção de crescimento podem ser resultantes da proximidade com outros espécimes, o que sugere capacidade sensoriais que auxiliariam na ocupação do substrato. Os resultados de MEV demonstraram que geralmente a microestrutura não está preservada, mas em alguns casos pode-se notar microgrânulos de calcita e um padrão reticulado. Conjuntamente com MEV, em análises petrográficas foram observadas duas camadas formando a parede de Cloudina. As análises geoquímicas de EDS e Raman demonstraram a presença de carbono na concha e corroboram trabalhos anteriores que postularam uma concha rica em matéria orgânica. As quantidades de Mg% e MgO% verificadas por EDS caracterizaram os fósseis da Formação Tamengo como de baixo teor de magnésio e fitting de bandas de calcita em espectros Raman fortalecem essa interpretação. Mesmo assim, alterações diagenéticas de estabilização por perda de Mg podem ter ocorrido. Os resultados de XRF-SRS mostraram que não há variação de Sr maior que 1000 ppm entre o fóssil e a rocha, indicando que, pelo menos, a mineralogia da concha não era aragonítica. Sendo assim, o presente trabalho traz novos cenários para a paleobiologia de Cloudina da Fm. Tamengo: Cloudina lucianoi é considerado como tafotáxon pelo contexto tafonômico e análise biométrica, indica ambientes de vida associados com microbialitos e possíveis cianobactérias, relações simbióticas podem ter ocorrido entre esse metazoário e biofilmes, é inferido modo de vida horizontal a sub-horizontal, é sugerido comportamentos de competição por espaço, a esqueletogênese de Cloudina é caracterizada por funis compostos por uma parede com duas camadas, rica em matéria orgânica e com microgrânulos de calcita. / Cloudina was the first fossil of a biomineralized organism found in latest Ediacaran. Also in this period, there was Corumbella, Namacalathus, Sinotubulites and Namapoikia within the skeletal biota. In the Corumbá Group (MS), in carbonates and pelites of Tamengo Formation, occur the fossils of Cloudina and Corumbella, respectively. This work aims to analyze paleobiological questions regarding Cloudina, such as its taphonomical, taxonomical and paleoecological context. Geochemical and microstructural analyses were performed to better understand the skeletogenesis of this fossil. For this, were utilized paleometrical techniques, such: Raman Spectroscopy, Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Fluorescence Synchrotron based (XRF-SRS) - for chemical and mineralogical analyses; and Scanning Electron Microscopy (SEM) and Computerized Microtomography (MicroCT) - for imaging of non-visible surficial microstructures and morphological attributes. The taphonomical analyses of orientation revealed NNE-SSW and NE-SW, as well as WNW-ESSE patterns, indicating currents that varied from almost parallel, to, possibly, perpendicular with relation to the ancient coastline. The taphonomical alterations include fragmentation of the external portions of the flares, plastic deformation, neomorphism, dissolution of the wall and the presence of eodiagenetic calcite between the flares of the funnels. This taphonomical context suggests a deposition by reworking and indicates that morphological information, such as diameter, is taphonomical altered. The biometrical analysis for the allochthonous specimens indicated bimodality for the statistical populations of Cloudina considering one, two, three or four layers in cross section, and together with the normal size distribution for the autochthonous assemblage suggest a mixture of original populations of different sizes. These results bring implications to the taxonomy of Cloudina, defining C. lucianoi as a taphotaxon. The study of the autochthonous assemblage demonstrated the occurrence of Cloudina with biolaminites and microfossils, and strengthens the interpretation that this metazoan lived in habitats associated with microbialites. The presence of goethite and eodiagenetic calcite between the flares of Cloudina, as well as silicified microspheres suggest the presence of organic matter in these external portions of the organism that can be related to de development of possibly symbiotic biofilms. The horizontal life position verified for Cloudina in the autochthonous assemblage together with occurrences in other localities of vertical specimens indicates the versatility of the life modes of this organism. Also in this sample, individuals with changes in the growing direction could be resultant of the proximity with other specimens, suggesting sensorial capacities, which assisted in the occupation of the substrate. SEM results demonstrated that often the microstructure is not preserved, but in some cases can be noted microgranules of calcite and a reticulate pattern. Allied with SEM, in petrographic sections were observed two layers forming the wall of Cloudina. EDS and Raman analysis showed the presence of carbon in the carapace and corroborate previous studies that postulated a shell with high amount of organic matter. Quantities of Mg% and MgO% verified by EDS characterized the fossils as low-magnesian calcites and fitting of calcite bands from Raman spectra strengthen this interpretation. Nevertheless, diagenetical alterations of stabilization by loss of Mg could have occurred. The results from XRF-SRS showed that there is no great variation in the Sr content between the fossil and the rock matrix, indicating that the mineralogy was not aragonitic. Thus, this work brings new scenarios for the paleobiology of Cloudina from the Tamengo Fm: Cloudina lucianoi is considered as a taphotaxon by the taphonomical and biometrical results, indicates habitats associated with microbialites and possible cyanobacteria, symbiotic relations could have occurred between this metazoan and biofilms, is inferred a horizontal to sub-horizontal life position and behaviors for space competition, the skeletogenesis of Cloudina is characterized by funnels composed of a wall with two layers, rich in organic matter and with microgranules of calcite.

Les cténophores représentent l’un des quatre embranchements animaux extérieurs aux Bilateria. La majoritédes espèces sont planctoniques et gélatineuses, et sont reconnaissables à leurs huit rangées de peignes dont lebattement permet la nage. Leur systématique est encore de nos jours mal comprise. L'anatomie descténophores offre peu de caractères aussi bien pour placer la lignée dans l’arbre des métazoaires, que pourétablir les relations de parenté au sein de l’embranchement et délimiter les espèces, et jusqu’à présent lesdonnées moléculaires n’ont pas permis de résoudre ces problèmes de manière satisfaisante. L’objectif de cetravail de thèse est de contribuer à améliorer notre compréhension de l'évolution des cténophores àdifférentes échelles taxonomiques. A l’échelle des métazoaires, la position phylogénétique des cténophores aété abordée par une approche phylogénomique. Un effort significatif a été réalisé pour améliorerl’échantillonnage taxonomique à travers le séquençage et l’assemblage des transcriptomes de 22 espèces denon-Bilateria (cténophores, cnidaires, spongiaires). Deux jeux de données indépendants ont été analysés, lepremier représentant une mise à jour d’une supermatrice existante de 128 gènes ; le second (4235 gènes)ayant été entièrement construit de novo via un protocole original comportant la mise au point de nouvellesméthodes pour traiter de manière semi-automatisée les principales sources potentielles d’artéfact(contaminations, paralogies, données manquantes). Les résultats contredisent certaines études récentes enmontrant que les spongiaires et non les cténophores représentent le groupe-frère des autres métazoaires. Laposition exacte de ces derniers reste à ce stade incertaine (trois options se présentant suivant les analyses). Al’échelle intra-phylétique, l'analyse d'un jeu de données comprenant les marqueurs ADNr 18S et InternalTranscribed Spacers (ITS), associée à des analyses de gènes dupliqués chez les cténophores et aux analysesphylogénomiques précédentes, a permis de résoudre une grande partie des relations phylogénétiques entre lesordres et les familles de cténophores, tout en permettant de préciser la position de la racine. Enfin, à uneéchelle taxonomique plus fine, une comparaison approfondie entre deux espèces du genre Pleurobrachia aumoyen de marquages immunohistochimiques montre le potentiel de ces techniques comme source denouveaux caractères structuraux « micro-anatomiques » à valeur diagnostique pour la délimitation etl’identification des espèces de cténophores. En conclusion, ce travail se veut une contribution au progrès dela systématique d’un embranchement encore méconnu et d’une grande importance pour la compréhensiondes évènements anciens de l’évolution animale. / Ctenophores are one of the four animal phyla positioned outside from the Bilateria. Most ctenophore species are planktonic and gelatinous, and are easily recognisable by their eight comb rows used for swimming. Ctenophore systematics remains nowadays poorly understood. Anatomical characters do not help much in placing them within the animal tree, and similarly the grounds for establishment of their internal phylogeny as well as delimitation of species are notoriously weak due to a paucity of informative morpho-anatomical characters. Until now, the use of molecular data has failed to improve significantly this situation. The aim of this PhD thesis was to bring a contribution to our understanding of ctenophore evolution at different taxonomic scales. At the metazoan level, the position of ctenophores was addressed using a phylogenomic approach. Taxonomic sampling was significantly improved through sequencing and assembly of transcriptomes of 22 non-bilaterian species (belonging to ctenophores, cnidarians and sponges). Two independent datasets were analysed, one consisting in an update of an existing supermatrix of 128 genes, the other one (4235 genes) having been entirely built de novo, thanks to a newly-devised semi-automated protocol intended to eliminate all major potential causes of artefacts (contaminations, paralogies, missing data). Results clearly contradict recent phylogenomic studies which claimed Ctenophora to be the most early-diverging animal lineage, our analyses instead supporting Porifera as the sister-group to other metazoans. The exact position of ctenophores remains however uncertain at this stage, different conditions of analyses yielding three contradictory hypotheses as open possibilities. At the intra-phyletic level, analyses of a ADNr 18S and ITS (internal transcribed spacers) dataset, together with study of duplicated genes and the results of phylogenomic analyses, allowed resolving most phylogenetic relationships between ctenophore orders and families, including the placement of the ctenophore tree root. Finally, at smaller taxonomic scale, in-depth comparison between two species of the genus Pleurobrachia using immunohistochemistry demonstrates the potential of these techniques for uncovering new structural “micro-anatomical” characters useful for diagnosis and identification of ctenophore species. It is our hope that this work will contribute to improving the systematics of a poorly known phylum of great importance for understanding early animal evolution.

Orientador: Edson Aparecido Adriano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T00:18:24Z (GMT). No. of bitstreams: 1 Correa_LincolnLima_D.pdf: 2492729 bytes, checksum: 0ec971eebdb725d4092b6b62a80716ee (MD5) Previous issue date: 2014 / Resumo: Prochilodus lineatus, Hoplias aff. malabaricus e Clarias gariepinus, são comumente encontrados nas Bacias dos rios Grande e Mogi-Guaçu. O objetivo desse estudo é descrever a diversidade das espécies de metazoários parasitos que infectam estas três espécies de peixes coletados nos Rios Turvo e Mogi-Guaçu. As coletas foram realizadas com auxílio de redes de espera e ocorreram entre fevereiro de 2010 a junho de 2012 em três pontos de estudo: lagoa marginal do rio Turvo, no município de Nova Granada (SP); rio Mogi Guaçu (leito do rio próximo a Cachoeira de Emas e lagoas marginais), município de Pirassununga (SP). O trabalho foi dividido em três capítulos, sendo que o primeiro trata do inventário das espécies de metazoários que infectam as três espécies de peixes alvo do estudo. Os resultados mostraram que juntas, estas três espécies de peixes hospedavam 30 espécies de parasitos. Dentre os metazoários parasitos, o filo Nematoda foi o que apresentou maior riqueza de espécies. A espécie de hospedeiro que apresentou maior riqueza parasitária foi H. aff. malabaricus. Os espécimes de P. lineatus apresentaram infecção por duas espécies de monogeneas, uma de digenético e uma de acantocéfalo. Espécimes de C. gariepinus apresentaram infecção por três espécies de nematódeos e uma de acantocéfalo. O segundo capítulo envolveu o estudo taxonômico de três espécies de Monogenea do gênero Anacanthorus, sendo esta a primeira descrição de espécies deste gênero em peixes do gênero Hoplias. O terceiro capítulo trata do estudo taxonômico de uma nova espécie do gênero Vaigamus, a qual foi encontrada infectando filamento branquial de H. aff. malabaricus coletados em uma lagoa marginal do Rio Mogi-Guaçu. Este é a primeira descrição de parasito do gênero Vaigamus em peixes do gênero Hoplias, e é a terceira espécies descrita para este gênero / Abstract: The fish species Prochilodus lineatus, Hoplias aff. malabaricus and Clarias gariepinus are commonly found in the basins of the Rio Grande and Rio Mogi-Guaçu rivers. The aim of the present study was to create an inventory of species of metazoans that infect these three fish collected from the Turvo and Mogi-Guaçu River. Collections were performed with gill nets between February 2010 and June 2012 at three study points: Turvo river (an oxbow lake), in municipality of Nova Granada, São Paulo state, Brazil; Mogi Guaçu (river bed near the Cachoeira das Emas waterfall, and oxbow lakes) municipality of Pirassununga, São Paulo state, Brazil. The study was divided into three chapters. The first chapter features an inventory of the species of metazoans infecting the three fish species studied. The results show that together the three species of fish hosts 30 species of parasite. Among the metazoans, the phylum Nematoda presented the greatest richness of parasite species. The host species with the greatest parasitic richness was H. aff. malabaricus. Specimens of P. lineatus were infected by two monogenean, one digenean and one acanthocephalan species. Specimens of C. gariepinus were infected by three nematode and one acanthocephalan species. The second chapter involves the taxonomic study of three species of monogeneans of the Anacanthorus genus, the first description of species of the Anacanthorus genus in fish of the Hoplias genus. The third chapter is a taxonomic study of a new species of the Vaigamus genus, which was found infecting the gill filament of H. aff. malabaricus collected in an oxbow lake of the Mogi-Guaçu river. This is the first description of parasites of the Vaigamus genus in fish of the Hoplias genus, and is the third species identified for this genus / Doutorado / Parasitologia / Doutor em Parasitologia

No description available.

Patterns of variability in growth, development and mortality in early life histories were examined at two levels--general and specific. At the general level, I examined the functional significance of larvae in metazoan life cycles. This was achieved by surveying the metazoa at the class level and categorizing mode of development by habitat. Three long-standing hypotheses for the paucity of larval development in fresh water were rejected. I argue that viewing metazoan larvae as a means for feeding and growth provides a unifying framework for evaluating the features of habitats which correlate with the range of variation expressed in development modes. I offer a modelling framework to investigate variation in developmental modes within and between habitats. The suggested model requires input on larval growth rates, larval period duration (development time), and size-specific mortality rates. These variables, and the interactions between them, are also central to the specific analysis which addresses the ecological processes and mechanisms which affect survival and hence recruitment during the early life histories periods of marine fishes. Winter flounder (Pleuronectes americanus) was used as a model species to investigate phenotypic variability in patterns of growth and development and their survival consequences. Using laboratory-reared fish, I demonstrate that size-at-age does not diverge continuously during the larval and juvenile periods. The results show that fish which grow slowly as larvae, compensate for their slow growth by growing rapidly as juveniles. This compensation in growth rate causes juvenile size-at-age to converge, or at least, prevents divergence in juvenile size-at-age. In addition, I provide some of the first estimates of individual variability in larval growth trajectories for a marine fish. I conducted the first experiment which separates the effects of both size and age on the vulnerability to predation in recently metamorphosed fishes. Th

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Excystation, as applied to the coccidia, is the process by which sporozoites are released from sporocysts and oocysts. Although this process has long been a subject of interest and study, there still remains considerable disagreement among investigators as to the mechanism by which the process occurs and the factors which are involved.