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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Population genetics of Colletotrichum truncatum associated with soybean anthracnose / Genética populacional de Colletotrichum truncatum associado à antracnose da soja

Rogério, Flávia 05 July 2019 (has links)
The soybean crop is one of the main agricultural crops, with high global economic relevance. The large area under soybean cultivation in Brazil, including the incorporation of new areas in the northern and midwestern regions, mostly under monoculture and non-tillage system, has been affected the prevalence and the intensity of diseases. Among these, one of most prominent is anthracnose, mainly associated with the fungal species Colletotrichum truncatum. Knowledge of the genetic structure of plant pathogen populations can be used to infer their life histories and the evolutionary processes that shape populations in the agroecosystems, which can help to implement effective disease management strategies. However, the genetic structure of C. truncatum populations associated with soybean remains unknown. We collected C. truncatum isolates from 10 sites representing two of main areas of soybean producing in Brazil and used microsatellite markers and whole-genome sequencing to investigate the population biology and evolutionary history of this important pathogen. The multilocus microsatellite typing of 237 isolates revealed high gene and haplotypic diversity within populations, as well low genetic differentiation and sharing of multilocus haplotypes among populations and regions. In addition, three distinct genetic clusters were detected, coexisting in syntopy in the soybean fields, without evidence of admixture between them. Such finding suggesting that Brazilian C. truncatum populations resulted from at least three founder events, which led to three genetic lineages that spread throughout the country. However, the genetic makeup of these lineages remains unknow, and their extreme geographic proximity raises the question of the maintenance of their genetic integrity in the face of admixture. In order to gain insights into the evolutionary history of C. truncatum lineages and to investigate in more details the possibility of a lack of genetic exchanges between them, we employed a population genomic approach. For that, we produced a draft genome sequence of a typical strain of the species associated with soybean anthracnose, which was used as the reference genome. Eighteen representative C. truncatum isolates from the three lineages were submitted to whole genome sequencing, aligned against the reference genome, and variants were identified. Our population genomic analyzes revealed that the genetic structure of C. truncatum pathogen causing soybean anthracnose is formed by three deeply divergent lineages with levels of genetic diversity consistent with repeated introduction events for each lineage. We also found evidence for sexual recombination within and between lineages, with multiples isolates displaying signatures of admixture. Our findings support a scenario in which the three lineages initially diverged in allopatry before experiencing hybridization following secondary contact. Monitoring of the pathogen\'s diversity over time is needed to reveal whether these lineages maintain or fuse, which can impact the disease control methods currently employed. / A soja é uma das principais culturas agrícolas, com alta relevância econômica global. A grande área sob cultivo de soja no Brasil, incluindo a incorporação de novas áreas nas regiões norte e centro-oeste, principalmente sob monocultura e plantio direto, tem afetado a prevalência e a intensidade das doenças. Entre elas, uma das mais proeminentes é a antracnose, principalmente associada à espécie fúngica Colletotrichum truncatum. O conhecimento da estrutura genética das populações de patógenos de plantas pode ser usado para inferir suas histórias de vida e os processos evolutivos que moldam as populações nos agroecossistemas, o que pode ajudar a implementar estratégias eficazes de manejo da doença. No entanto, a estrutura genética das populações de C. truncatum associadas à soja permanece desconhecida. Coletamos isolados de C. truncatum em 10 áreas, representando duas principais regiões produtoras de soja no Brasil. Utilizamos marcadores microssatélites e sequenciamento do genoma completo para investigar a biologia populacional e a história evolutiva desse importante patógeno. A tipagem de microssatélites multilocus de 237 isolados revelou alta diversidade genética e haplotípica nas populações, bem como baixa diferenciação genética e compartilhamento de haplótipos entre populações e regiões. Além disso, foram detectados três grupos genéticos distintos, coexistindo nas mesmas áreas, sem evidência de mistura entre eles. Isto sugere que as populações C. truncatum no Brasil resultaram de pelo menos três eventos fundadores, o que levou á formação das três linhagens genéticas que se espalharam pelo país. No entanto, a composição genética dessas linhagens permanece desconhecida, e sua extrema proximidade geográfica levanta a questão sobre a manutenção de sua integridade genética em face a mistura entre elas. A fim de analisar a história evolutiva das linhagens de C. truncatum e investigar a possibilidade de ausência de trocas genéticas entre elas, empregamos uma abordagem genômica populacional. Para isso, produzimos uma versão preliminar do genoma completo de um isolado típico da espécie, o qual foi utilizado como genoma de referência. Dezoito isolados representativos das três linhagens foram submetidos ao sequenciamento completo, alinhados ao genoma de referência, e variantes foram identificados. Nossas análises genômicas populacionais revelaram que a estrutura genética do patógeno é formada por três linhagens profundamente divergentes, com níveis de diversidade consistentes com repetidos eventos de introdução para cada linhagem. Também encontramos evidências de recombinação sexual dentro e entre linhagens, com múltiplos isolados apresentando assinaturas de mistura. Nossas descobertas sugerem um cenário no qual as três linhagens divergiram inicialmente em alopatria antes de experimentar hibridação, após contato secundário. O monitoramento da diversidade do patógeno ao longo do tempo é necessário para revelar se essas linhagens se mantêm geneticamente separadas ou se fundem, o que pode afetar os métodos de controle da doença atualmente empregados.
32

Maternal lineages and diversity of the growth hormone gene of South African goat populations

Ncube, Keabetswe Tebogo 09 1900 (has links)
The maternal lineages and origins of the South African goat populations are unknown and hence pose challenges for breed characterization and conservation. This study investigated the maternal lineages of South African goats using complete mtDNA and ascertained the genetic diversity in the growth hormone gene within and between populations. Illumina MiSeq next generation sequencing was used to generate the full length of the mtDNA (16.64 kb) and growth hormone (2.54kb) genes in 50 goats of the commercial South African Boer (n =9), captive feral Tankwa (n =9), and SA village goat populations (n =32). The non-descript village populations were sampled from villages of the four major goat-producing provinces; (i) Hobeni village, Elliotdale municipality and Pechelsdam village, Inxubayethemba municipality in Eastern Cape (n=8), (ii) Coniliva and Ngubo villages in Msinga municipality Kwa-Zulu Natal (n=8), (iii) Mukovhabale village, Mutale municipality and Muila-muumone, Makhado municipality in Limpopo (n=8) and (iv) Pella village (n=6), Moses Kotane municipality North West (n=8) provinces of South Africa. A total of 184 SNPs and 55 AA changes were observed across the complete mtDNA genome. High within-population variation was observed in all the groups, ranging from 98.60 to 99.52%. A low FST (FST = 0.003-0.049) indicated close relatedness and possible gene flow between SA goat populations. Haplotypes and clades observed in the D-loop, COX1 and whole mtDNA network trees demonstrated relationships between South African goat populations. The South African goats clustered with Chinese goats from lineages A and B, suggesting common maternal lineages between the Chinese and South African goat populations. The results also suggested that the bezoar (Capra aegagrus) is a possible ancestor of South African domestic goats. A range of 27 to 58 SNPs per population were observed on the growth hormone gene. Amino acid changes from glycine to serine, tyrosine to cysteine and arginine to glycine were observed at exon 2 and exon 5. Gene diversity ranged from 0.8268 ± 0.0410 to 0.9298 ± 0.0050. Higher within breed diversity (97.37%) was observed within the population category consisting of SA village ecotypes and the Tankwa goats. Highest pairwise FST values ranging from 0.148 to 0.356 were observed between the SA Boer and both the SA village and Tankwa feral goat populations. The maximum likelihood phylogenetic analysis indicated nine genetic clades, which reflected close relationships between the South African populations and the other international breeds. Results imply greater potential for within population selection programs particularly with SA village goats. / Life and Consumer Sciences / M.Sc. (Statistical Genomics)
33

Dos limites do Estado, da democracia e do direito em Oliveira Vianna e Raymundo Faoro / The limits the State, democracy and legal debate in Oliveira Vianna and Raymundo Faoro

Daniel Bianchi 01 March 2011 (has links)
Este estudo procura levantar as divergências e convergências entre Oliveira Vianna e Raymundo Faoro. Suas teses divergem por serem paradigmáticas de duas linhagens opostas do pensamento político e social brasileiro respectivamente, a do idealismo orgânico e a do idealismo constitucional. Entretanto, ao mesmo tempo existem inúmeros pontos de cruzamentos entre essas linhagens: focalizamos, sobretudo, aqueles relacionados com o fato de Vianna e Faoro estarem vinculados a um debate jurídico sobre os limites do Estado Democrático de Direito, que perpassou a história do Brasil ao longo do século XX. Para tanto, analisamos a participação de Vianna no momento constituinte da década de 1930 e de Faoro na década de 1980 e o fato de ambos terem enfrentado o mesmo oponente, qual seja, a elite dirigente que, na visão dos dois autores, importava instituições políticas estrangeiras e imaginava ser possível mudar o país exclusivamente por meio de leis produzindo, assim, um país legal em descompasso com o país real. / This study explores the differences and similarities between Oliveira Vianna and Raymundo Faoro. Their theses diverge because they are paradigmatic of two opposing lines of the Brazilian political and social thought - respectively, the organic idealism and the constitutional idealism. However, there are numerous points of intersection between the lines mentioned. We emphasize the points of intersection related to the fact that Vianna and Faoro were both engaged in the legal debate about the limits of the democratic state; which pervaded the history of Brazil throughout the 20th century. More precisely, we analyze the participation of Vianna in the period of the constituent assemblies, in the 1930s, and the activities of Faoro in the 1980s, as well as the fact that they both faced the same opponent, that is, the ruling elite. In the opinion of both authors, this elite imported foreign political institutions, and considered it possible to change the country based exclusively on laws then creating a legal country that mismatched with the real country.
34

Estrutura genética em populações de bracatinga (Mimosa scabrella Benth. ) por marcador isoenzimático e caracteres quantitativos. / Genetic structure in bracatinga populations (Mimosa scabrella Benth.) for quantitative traids and isozyme markers.

Graciela da Rocha Sobierajski 03 December 2004 (has links)
A Mimosa scabrella Bentham bracatinga) é uma espécie arbórea nativa da Mata Atlântica, de ocorrência restrita aos Estados do sul e sudeste do Brasil (RS, SC, PR, SP). A espécie vem sendo cultivada no sul do país e em outros países como Costa Rica e Ruanda, para os mais variados fins. Contudo, embora a espécie tenha diversas utilidades, muito pouco tem sido feito em termos de melhoramento genético. Assim, em Maio de 2003, um teste de procedências e progênies de M. scabrella foi instalado na Estação Experimental de Itatinga (ESALQ/USP), utilizando oito procedências nativas e uma comercial, coletadas ao longo da distribuição geográfica da espécie. O delineamento usado foi o Blocos de Famílias Compactas, com nove procedências, 10 a 20 progênies por procedência, seis plantas por subparcela e cinco repetições. Seis meses após o plantio foi medido o caráter altura total e sobrevivência de plantas no ensaio. Concomitantemente, uma amostra de aproximadamente 50 plantas por procedência foi usada para a analise de eletroforese de isoenzimas, revelando-se sete locos polimórficos. Os resultados mostraram que a espécie tem sistema misto de reprodução com predomínio de cruzamentos (média de tm = 0,971). Na média das procedências foi detectada 7,6% de cruzamento entre indivíduos parentes e 51,3% de cruzamentos biparentais, indicando fortes desvios de cruzamentos aleatórios e que as progênies são constituídas por misturas de diferentes tipos de parentescos. Em concordância, o coeficiente médio de parentesco entre plantas dentro de progênies foi alto (0,392). A análise da diversidade genética detectou altos níveis de heterozigosidades (He = 0,580; Ho = 530), embora em duas procedências (Caçador-SC e Ituporanga comercial-PR) foram detectados excessos significativos de homozigotos em relação ao esperado sob Equilíbrio de Hardy-Weinberg. O estudo da associação entre distância genética de Nei (1978) com a distância geográfica entre procedências, usando o teste de Mantel, não detectou correlação significativa (r=0,198 ; P=159), de forma que não é possível atribuir o padrão de distância genética observado entre procedências ao modelo isolamento por distância. A comparação da medida de divergência genética entre procedências detectada por caracteres quantitativos (Qp = 0,039) com a detectada por locos isoenzimáticos (θp =0,018) sugere que a divergência genética quantitativa observada entre as procedências aos seis meses de idade para o caráter altura foi causada por seleção divergente (Qp>θp). Parâmetros genéticos foram estimados para o caráter altura, usando os modelos aleatório (assume progênies de polinização livre como meios-irmãos) e misto de reprodução (assume progênies de polinização livre como misturas de diferentes parentescos). A estimativas da variância genética aditiva, os coeficientes de herdabilidade e os ganhos esperados na seleção foram superestimados em 36%, 48% e 41%, respectivamente, quando o modelo aleatório de reprodução foi usado ao invés do modelo misto de reprodução. / Mimosa scabrella Bentham (Bracatinga), is a native tree species of Atlantic Forest, of restricted occurrence to the Southwest and South of Brazil (RS, SC, PR and SP). The species comes being cultivated in the Brazil south and in the other countries as Costa Rica and Ruanda, for the most varied ends. But, although the species has a varied ends, lack studies in the genetic breeding. Thus, in May of 2003, a M. scabrella provenance progeny test was implanted in the Experimental Station of Itatinga (ESALQ/USP). The design used was the Compact Family Block with eight provenances, 10 to 20 families per provenance, six plants per subplot and five replications (block). Total height and survival at six months old were measured in the trials. Concomitantly, a sampled of about 50 plants per provenance was used to analyses of isozymes electrophoresis, reveling seven polymorphic loci. The results showed that the species has a mixed mating system with outcrossing predominance (average tm = 0.971). In the provenance average was detected 7.6% of biparental inbreeding and 51.3% of biparental outcrossing, indicating strong deviations of random mating and that the families are mixtures of different relatedness kinds. In agreement, the average relatedness coefficient among plant within families was high (0.392). The analyses of genetic diversity detected high levels of observed and expected heterozygosities (He = 0.580; Ho = 530, respectively), although in two provenances (Caçador-SC and Ituporanga comercial-PR) were detected significant excess of homozygotes in relationship to expected in Hardy-Weinberg equilibrium. The studied of association among Nei (1978) genetic distance and geographic distances among provenances, using Mantel test, no detected significant correlation (r = 198; P = 159), indicating that the observed genetic distance among provenance patters is not possible to attribute the isolation distance model. The comparison of genetic divergence among provenance measured by quantitative traits (Qp = 0.039) with the measure by isozymes loci ( θp = 0.018) suggest that the quantitative genetic divergence among provenance at six months old to height trait was caused by divergent selection ( Qp > θp ). Genetic parameters were estimated to height trait, using the random (assume open-pollinated arrays with half-sibs) and mixed (assume open-pollinated arrays with mixed of different relatedness kinds) mating model. The additive genetic variance, heritabilities coefficients and expected gain selection were 36%, 48% and 41%, respectively, super-estimates, where a random model was used instead of mixed mating model.
35

The Evolving Faces of the SARS-CoV-2 Genome

Schmidt, Maria, Arshad, Mamoona, Bernhart, Stephan H., Hakobyan, Siras, Arakelyan, Arsen, Loeffler-Wirth, Henry, Binder, Hans 09 May 2023 (has links)
Surveillance of the evolving SARS-CoV-2 genome combined with epidemiological monitoring and emerging vaccination became paramount tasks to control the pandemic which is rapidly changing in time and space. Genomic surveillance must combine generation and sharing sequence data with appropriate bioinformatics monitoring and analysis methods. We applied molecular portrayal using self-organizing maps machine learning (SOM portrayal) to characterize the diversity of the virus genomes, their mutual relatedness and development since the beginning of the pandemic. The genetic landscape obtained visualizes the relevant mutations in a lineage-specific fashion and provides developmental paths in genetic state space from early lineages towards the variants of concern alpha, beta, gamma and delta. The different genes of the virus have specific footprints in the landscape reflecting their biological impact. SOM portrayal provides a novel option for ‘bioinformatics surveillance’ of the pandemic, with strong odds regarding visualization, intuitive perception and ‘personalization’ of the mutational patterns of the virus genomes.
36

Une invasion dans la discrétion : répartition, origines et expansion des limaces européennes du complexe d'Arion subfuscus s.l. au Québec

L'Heureux, Érik 09 1900 (has links)
Une identification précise des espèces exotiques est essentielle afin de déterminer la nature et l’ampleur des impacts que ces espèces auront sur leurs nouveaux habitats. Le complexe d’Arion subfuscus s. l., originaire d’Europe, fait partie des limaces les plus abondantes dans le nord-est de l’Amérique du Nord et plusieurs impacts dus à leur présence ont été rapportés. Cependant, l’identité des espèces introduites demeure inconnue dans la plupart des régions. L’objectif de ce projet est donc de déterminer la répartition récente, la diversité taxonomique et l’origine des membres du complexe d’A. subfuscus s. l. au Québec en se basant sur leur identité mitochondriale (16S rDNA). Un total de 526 spécimens provenant de 68 sites à travers le Québec et un site en Nouvelle-Écosse ont été analysés à l’aide de la technique des SSCP et leurs séquences ont été déterminées. Huit haplotypes de deux espèces allopatriques, A fuscus et A. subfuscus s. s. (lignées S1 et S2) ont été détectés. Les résultats confirment que des limaces provenant de régions distinctes d’Europe ont été introduites à de multiples reprises. Une comparaison avec des données historiques de répartition a révélé une expansion fulgurante de la répartition depuis les 50 dernières années. Arion fuscus est la principale espèce envahissante qui a été détectée dans toutes les régions échantillonnées, ce qui contraste avec les études antérieures réalisées ailleurs en Amérique du Nord. Le rôle potentiel des échanges commerciaux internationaux dans l’histoire d’introduction des espèces exotiques est discuté. / Accurate identification of exotic species is required to assess the magnitude and nature of consequences on their new habitats. The Arion subfuscus s. l. species complex comprised slugs of European origins that are amongst the most abundant slug species in northeastern North America and various impacts of their presence are reported. However, the identities of the species introduced remain unknown in most regions. This study aims at determining the current distribution, taxonomic identity and the origins of the members of the A. subfuscus s. l. complex in Quebec (Canada) based on mitochondrial 16S rDNA. A total of 526 specimens from 68 locations throughout Quebec and one site in Nova Scotia were SSCP analysed and their sequences were determined. Eight haplotypes of the allopatric A. fuscus and A. subfuscus s. s. (lineages S1 and S2) were detected. Results confirmed that slugs from distinct European regions were introduced multiple times. Comparison with previous survey revealed an impressive expansion of the distribution during the last 50 years. Arion fuscus is the major invasive species found throughout Quebec, contrasting with previous North American studies. The potential role of international trade in the introduction history of exotic species is discussed.
37

Pratylenchus coffeae em cafeeiros: efeito de densidades populacionais do nematóide e testes com genótipos. / Pratylenchus coffeae in coffee plants: effect of initial population densities and tests with genotypes.

Tomazini, Melissa Dall'Oglio 26 January 2004 (has links)
O nematóide das lesões Pratylenchus coffeae é um dos principais parasitos do cafeeiro e de outras culturas e sua variabilidade biológica, que dificulta a adoção de métodos de controle, contribui para aumentar a sua importância no Brasil. Pela importância da cafeicultura e a falta de estudos com esse nematóide no Brasil, foram realizados experimentos com dois de seus isolados (K5 e M2), com os objetivos de correlacionar densidades populacionais do nematóide aos danos causados e estabelecer possíveis fontes de resistência de cafeeiros ao isolado K5. Foram testadas diferentes densidades populacionais iniciais do isolado M2 em plantas (seis pares de folhas) e plântulas (dois pares de folhas) do cafeeiro arábico ‘Catuaí Vermelho’. As densidades populacionais utilizadas foram de 0, 333, 1.000, 3.000 e 9.000 nematóides por plântula ou planta. A avaliação ocorreu aproximadamente cinco (plântulas) e sete (plantas) meses após a inoculação. Os resultados mostraram que houve uma acentuada redução do crescimento das plântulas, bem como massa fresca das raízes e massa seca da parte aérea, já a partir das densidades mais baixas. A variação populacional (Pf/Pi) foi menor que um (1,0) para todas as densidades de inóculo, indicando que esta cultivar, no estágio de plântulas com dois pares de folhas, mostrou-se intolerante ao parasitismo. Em relação à inoculação das plantas, já com seis pares de folhas, não houve diferenças significativas nas variáveis analisadas e ocorreram decréscimos populacionais do nematóide, indicando que, nessas condições, ‘Catuaí Vermelho’ mostrou-se resistente ao isolado M2. Em relação ao isolado K5, foram realizados cinco experimentos, visando caracterizar as reações de genótipos de Coffea canephora ('Robusta' e 'Conilon'), além de C. arabica ‘Mundo Novo’, comparado às reações frente ao nematóide de galhas Meloidogyne incognita raça 2. No Experimento 1, foram utilizadas plantas de C. arabica ‘Mundo Novo’, inoculadas com 1.480 nematóides por planta (isolado K5 e M. incognita). Após sete meses da inoculação foi feita a avaliação, mostrando que o crescimento populacional dos nematóides foi alto e a reação de suscetibilidade. Mesmo em mudas desenvolvidas de cafeeiro ‘Mundo Novo’, o isolado K5 destacou-se como tão agressivo quanto M. incognita. Os outros genótipos testados, de C. canephora, foram inoculados com 3.000 nematóides por planta. Nos Experimentos 2 e 3, as linhagens IAC 4804 e IAC 4810 de ‘Robusta’ foram suscetíveis ao isolado K5, mas em um deles (IAC 4804) ocorreu grande variação entre as repetições em relação à M. incognita. Apenas o isolado K5 promoveu redução do crescimento do cafeeiro, evidenciado na variável massa fresca das raízes, em ambas as linhagens, sendo que IAC 4810 comportou-se como resistente a M. incognita. No caso de C. canephora ‘Conilon’, ambas as linhagens testadas (IAC 4764 e IAC 4765) foram resistentes ao isolado K5 e suscetíveis a M. incognita. / The lesion-nematode Pratylenchus coffeae is a major pest of coffee and other economic crops and its biological variability, which often makes difficult the adoption of control methods, contributes to increase the importance of this parasite in Brazil. Due to the importance of coffee production and the lack of studies involving this nematode species in Brazil, experiments were set with two of its available isolates (K5 and M2) to correlate initial population densities with the damage caused on coffee plants and to establish possible resistance sources in relation to the isolate K5. Different population densities of isolate M2 were tested in plants (six pairs of leaves) and seedlings (two pairs of leaves) of Coffea arabica ‘Catuaí Vermelho’. The population densities (Pi) were: 0, 333, 1.000, 3.000 and 9.000 nematodes per seedling or plant. The evaluation was done at approximately five (seedlings) and seven (plants) months after inoculation. The results showed that there was a marked reduction of the height, as well as root fresh weight and shoot dry weight of the seedlings, starting from the lower Pi values. The nematode population decreased (Pf/Pi < 1), indicating that this cultivar, at the seedling stage, was intolerant to parasitism. In relation to the inoculation of older plants, there were no significant differences in the growth parameters and the nematode population also decreased allowing ‘Catuaí Vermelho’ to be rated as resistant to the isolate M2. In relation to isolate K5, five experiments (referred to as 1, 2, 3, 4, and 5) were set to characterize the reaction of different genotypes of Coffea canephora ('Robusta' and 'Conilon') and C. arabica ‘Mundo Novo', as compared with their reaction to the root-knot nematode Meloidogyne incognita race 2. In Experiment 1, plants of C. arabica ‘Mundo Novo’ were inoculated with 1,480 nematodes per plant (K5 and M. incognita). The final evaluation after seven months of the inoculation showed a high populational increase of the nematodes and that both were pathogenic at a same extent. The other genotypes tested, belonging to C. canephora, were inoculated with 3,000 nematodes per plant. The genotypes (IAC 4804 and IAC 4810) of ‘Robusta’ were susceptible to isolate K5, but in one of them (IAC 4804) there was great variation among the repetitions in relation to M. incognita. The isolate K5 caused marked reduction in the growth of coffee Robusta plants as evidenced particularly through the root fresh weight values in both tested genotypes; in addition, IAC 4810 was rated as resistant to M. incognita. With regard to C. canephora 'Conilon', both tested genotypes (IAC 4764 and IAC 4765) were resistant to isolate K5 and susceptible to M. incognita.
38

Molecular and cellular characterization of apical and basal progenitors in the primate developing cerebral cortex / Caractérisation cellulaire et moléculaire des progéniteurs apicaux et basaux lors du développement du cortex cérébral chez le primate

Betizeau, Marion 24 October 2013 (has links)
Le cortex cérébral primate a subi des modifications majeures pendant l'évolution qui ont permis le développement de fonctions cognitives supérieures. Un accroissement massif a eu lieu avec l'extension spécifique des couches supragranulaires et une forte expansion tangentielle. Le cortex primate ne possède pas uniquement davantage de neurones, comparé au rongeur, mais aussi des différences qualitatives. Ceci suggère des différences qualitatives pendant le développement du cortex.Une zone proliférative corticale supplémentaire a été identifiée chez le singe macaque: la zone subventriculaire externe (OSVZ) supposée être impliquée dans l'expansion du cortex primate. Mais les propriétés des précurseurs de l'OSVZ restent mal connues. Des techniques de microscopie en temps réel et d'immunofluorescence ont permis de réaliser une description exhaustive des précurseurs de l'OSVZ et de leurs propriétés chez le singe macaque.Nos résultats mettent en évidence des différences primates/rongeurs majeures. Les observations en temps réel révèlent des capacités prolifératives bien plus importantes des précurseurs. Les précurseurs primates de l'OSVZ présentent des taux de prolifération variables pendant la corticogenèse liés à la cinétique du cycle cellulaire. Nos enregistrements ont permis la génération d'une grande base de données de propriétés et lignages de précurseurs et la mise en évidence d’une diversité morphologique inattendue. 5 types ont été identifiés. Impliqués dans des lignages complexes, chaque type a la capacité de s'auto-renouveler et de générer directement des neurones. Parallèlement, nous avons développé une méthode de classification non supervisée des précurseurs corticaux. Cette technique a identifié les mêmes 5 types de précurseurs.Les résultats de cette thèse apportent de nouveaux éléments dans la compréhension des spécificités de la corticogenèse primate qui contribuent à l'expansion corticale et au développement de capacités cognitives supérieures. / The primate cerebral cortex underwent major modifications during evolution that enabled the development of high cognitive functions. A massive enlargement occurred with the specific expansion of the supra granular layers and the apparition of new frontal areas. Not only quantitative differences are found compared to the rodent but also qualitative differences. This points to potential qualitative differences in primate cortical development. An extra proliferating zone had already been identified during macaque corticogenesis: the outer subventricular zone (OSVZ). This zone is assumed to play a key role in the expansion of the primate cortex but the cellular and functional properties of OSVZ precursors remain elusive. We used quantitative long-term time-lapse video-microscopy (TLV) and immunofluorescence in and ex vivo to perform a detailed and exhaustive description of OSVZ precursor types and proliferative abilities at different stages of macaque cortical development. Our results highlight major rodent/primate differences. TLV observations revealed a much higher proliferative potential of OSVZ compared to the rodent SVZ. We report variable rates of proliferation linked to cell-cycle duration in a stage-specific manner. TLV recordings allowed the formation of a large database of primate precursor properties and lineages. This dataset unravelled an unexpectedly high diversity of OSVZ precursor morphologies. Five precursor types were identified. Involved in complex lineages, each precursor type can self-renew and directly generate neurons. In a parallel approach, we developed an unbiased clustering tool to automatically classify cortical precursors. This technique returned the same five precursor types as the morphological categorization. The results of this PhD thesis provide new insights into primate specificities during corticogenesis that contribute to cortical expansion and to the development of higher cognitive abilities.
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Variação genética e morfológica das espécies de Thoropa Cope, 1865 (Anura : Cycloramphidae) /

Sabbag, Ariadne Fares. January 2019 (has links)
Orientador: Célio Fernando Baptista Haddad / Resumo: Thoropa Cope, 1865 (Anura: Cycloramphidae) é um gênero de rãs endêmicas do domínio Mata Atlântica e de ecótonos associados. Possui atualmente seis espécies (T. miliaris, T. petropolitana, T. taophora, T. lutzi, T. megatympanum e T. saxatilis), divididas em dois grupos morfológicos: grupo petropolitana (T. petropolitana e T. lutzi) e grupo miliaris (T. miliaris, T. taophora, T. megatympanum e T. saxatilis). Todas as espécies se reproduzem e se desenvolvem em rochas molhadas de água doce, encontradas em afloramentos rochosos, cachoeiras e riachos. Um estudo recente sobre a filogenia molecular mostrou que T. miliaris é parafilética a T. taophora, e que T. taophora, T. megatympanum e T. saxatilis são monofiléticas com alto suporte (Sabbag et al. 2018). Esse estudo também encontrou diversos clados dentro de cada uma das espécies, especialmente em T. miliaris. Porém, não foi possível estudarem molecularmente as espécies do grupo petropolitana porque existe apenas uma amostra de DNA disponível para o grupo. No presente trabalho, estudamos aspectos genéticos e morfológicos das seis espécies do gênero a fim de investigar a diversidade molecular previamente encontrada, a parafilia de T. miliaris e as características morfológicas das espécies que coincidam com a diversidade genética conhecida. Encontramos que os clados conhecidos de T. miliaris são linhagens evoluindo separadamente e que os clados conhecidos de T. taophora fazem parte de uma linhagem única. Thoropa miliaris e T. taophor... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Thoropa Cope, 1865 (Anura: Cycloramphidae) is a frog genus endemic to theAtlantic forest domain and associated ecotones. It comprises six species (T. miliaris, T. petropolitana, T. taophora, T. lutzi, T. megatympanum and T. saxatilis), divided in two morphological groups: petropolitana group (T. petropolitana and T. lutzi) and miliaris group (T. miliaris, T. taophora, T. megatympanum and T. saxatilis). All the species reproduce and develop in freshwater wet rocks that can be found in rock outcrops, waterfalls and streams. A recent study on molecular phylogeny has shown that T. miliaris is paraphyletic in respect to T. taophora and that T. taophora, T. megatympanum and T. saxatilis are monophyletic with high support. This study also found many clades inside each of those species, especially within T. miliaris. Nevertheless, it was not possible to study molecular aspects of the petropolitana group because there is only one DNA sample available for the group. In this work, we studied genetic and morphological aspects of all six species of the genus in order to investigate the molecular diversity found previously, the paraphyly found for T. miliaris, and the species morphological characteristics that coincide with the known genetic diversity. We found that the known clades of T. miliaris are separately evolving lineages and that the clades of T. taophora are part of a whole lineage. Thoropa miliaris and T. taophora are reciprocally monophyletic. We also found that the diversifica... (Complete abstract click electronic access below) / Doutor
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A Framework for Individual-based Simulation of Heterogeneous Cell Populations

Abdennur, Nezar A 13 December 2011 (has links)
An object-oriented framework is presented for developing and simulating individual-based models of cell populations. The framework supplies classes to define objects called simulation channels that encapsulate the algorithms that make up a simulation model. These may govern state-updating events at the individual level, perform global state changes, or trigger cell division. Simulation engines control the scheduling and execution of collections of simulation channels, while a simulation manager coordinates the engines according to one of two scheduling protocols. When the ensemble of cells being simulated reaches a specified maximum size, a procedure is introduced whereby random cells are ejected from the simulation and replaced by newborn cells to keep the sample population size constant but representative in composition. The framework permits recording of population snapshot data and/or cell lineage histories. Use of the framework is demonstrated through validation benchmarks and two case studies based on experiments from the literature.

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