Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Bibliography: p.157-158

Thesis (Ph.D.). / Written for the Institute of parasitology. Title from title page of PDF (viewed 2009/06/10). Includes bibliographical references.

Thesis--Carleton University. / Also available in electronic format on the Internet.

Thesis (Ph. D.)--Case Western Reserve University, 2005. / [School of Medicine] Department of Genetics. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Thesis (Ph.D.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Medical Microbiology and Immunology. Title from pdf file main screen (viewed on April 24, 2010). Includes bibliographical references.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Restricted until October 2005. Bibliography: leaves 104-113.

Thesis (Ph. D. in Physics)--Vanderbilt University, May 2006. / Title from title screen. Includes bibliographical references.

Patologias causadas por mutações no DNA mitocondrial (mtDNA) constituem um importante grupo de doenças genéticas em humanos. Todavia, devido ao desconhecimento dos mecanismos que governam a herança mitocondrial, não existem métodos eficientes que permitam prever ou intervir na herança destas patologias. Estudos recentes indicam que mutações no mtDNA são seletivamente eliminadas na linhagem germinativa. O presente projeto investigou se o embrião é capaz de eliminar mitocôndrias disfuncionais durante o desenvolvimento pré-implantação. Para tanto, zigotos de camundongo foram tratados com clorometil-X-rosamina (MitoTracker Red CMXRos) e fotossensibilizados por 0, 2,5, 5, 10, 20 e 60 s. Houve diminuição da taxa de blastocisto, com bloqueio total do desenvolvimento quando a fotossensibilização foi realizada por período igual ou superior a 20 s. A fotossensibilização também resultou em disfunção mitocondrial, como indicado por diminuição do potencial de membrana mitocondrial. No entanto, a transferência de citoplasma de zigotos NZB/BINJ (NZB) fotossensibilizados por 20 s não afetou o desenvolvimento de embriões C57BL/6 (B6). A quantidade de mtDNA NZB também não diferiu entre os zigotos B6, independente de terem recebido citoplasma exposto ou não à fotossensibilização (30,6% ± 1,73 vs. 30,8% ± 1,73). Porém, a quantidade de mtDNA NZB foi menor (P = 0,008) nos blastocistos que receberam citoplasma fotossensibilizado (31,4% ± 1,43 vs. 24,7% ± 1,43). Como a quantidade total de mtDNA não diferiu entre os grupos, estes resultados sugerem que as mitocôndrias disfuncionais introduzidas foram destruídas. A análise de autofagossomos indicou, no entanto, que as mitocôndrias NZB não foram eliminadas por mitofagia. Diferente do esperado, o cultivo na presença de rapamicina reverteu o efeito causado pela introdução de citoplasma fotossensibilizado, resultando em níveis semelhantes de mtDNA NZB em comparação com os blastocistos que receberam citoplasma não fotossensibilizado. Concluiu-se que o embrião de camundongo é capaz de destruir mitocôndrias disfuncionais durante o desenvolvimento à blastocisto. Novos estudos deverão fornecer evidências adicionais e esclarecer os mecanismos moleculares que fundamentam esses achados. / Pathologies caused by mutations in mitochondrial DNA (mtDNA) represent an important group of genetic diseases in humans. Nonetheless, due to our limited understanding of the molecular mechanisms of mitochondrial inheritance there are no efficient methods to predict or intervene in the inheritance of these diseases. Recent studies indicate that mutations in mtDNA are selectively eliminated in the germline. This project investigated the ability of the embryo to target and eliminate dysfunctional mitochondria during early development. To test that, mouse zygotes were treated with chloromethyl-X-rosamina (MitoTracker Red CMXRos) and photosensitized for 0, 2.5, 5, 10, 20 and 60 s. There was a decrease in the rate of blastocyst development and a developmental arrest when the photosensitization was performed for a period equal to or greater than 20 s. Photosensitization also resulted in mitochondrial dysfunction, as indicated by a decreased of mitochondrial membrane potential. However, cytoplasmic transfer from NZB/BINJ (NZB) zygotes photosensitized for 20 s resulted in no effect on development of C57BL/6 (B6) embryos. The amount of NZB mtDNA introduced also did not differ between B6 zygotes, regardless of whether they received or not photosensitized cytoplasm (30.6% ± 1.73 vs. 30.8 ± 1.73%). On the other hand, the amount of NZB mtDNA was lower (P = 0.008) in the blastocysts receiving photosensitized cytoplasm (31.4% ± 24.7% ± 1.43 vs. 1.43). Since the total amount of mtDNA was not different between the groups, these results suggest that dysfunctional mitochondria introduced by cytoplasmic transfer were destroyed. Analysis of autophagosomes indicated, however, that the NZB mitochondria were not eliminated by mitophagy. Different than expected, culture in the presence of rapamycin reversed the effect caused by introduction of photosensitized cytoplasm, resulting in similar levels of NZB mtDNA compared to blastocysts receiving cytoplasm not photosensitized. It was concluded that the mouse embryo may destroy dysfunctional mitochondria during development into blastocysts. Further studies should provide additional evidence and elucidate the molecular mechanisms underlying these findings.

O presente trabalho teve como objetivo avaliar os efeitos da introdução da linhagem materna, representando a herança mitocondrial, no modelo de avaliação genética para características de desenvolvimento (peso ao nascer, aos 120 dias, a desmama, ao ano e ao sobreano), perímetro escrotal e temperamento de um rebanho Nelore. O banco de dados era composto pelo registro de produção de 24.498 animais e o de genealogia, de 27.476. Com o intuito de estimar componentes de (co)variâncias e parâmetros genéticos, os dados foram analisados sob dois modelos, o primeiro igual ao atualmente utilizado nas avaliações genéticas desse rebanho, e o segundo incluiu o efeito de linhagem materna como efeito aleatório. A linhagem materna foi obtida traçando-se a partir de uma fêmea, uma linha até a última fêmea com registro no banco de dados, considerando-a uma fundadora. Dentre as características analisadas, o efeito de linhagem materna foi significativo (P < 0,05) somente para peso à desmama. Para essa característica, o efeito de linhagem materna foi responsável por grande alteração do "ranking" dos 1000 melhores animais, tanto para machos quanto para fêmeas. A variação entre as linhagens maternas pode promover diferenças de mais de 22 kg no peso a desmama, o que corresponde a 12,9% da média fenotípica / The present work had the objective to evaluate the effect of the introduction of the maternal lineage, representing the mitocondrial inheritance, in the model of genetic evaluation for growth characteristics (weights at birth, 120 days, weaning, year and 18 months), scrotal perimeter and temperament of one Nelore herd. The data base was composed of 24.498 animals and pedigree, of 27.476. With intention of estimating the (co)variance components and genetic parameters, data were analyzed under two models: first the equal one that currently used in the genetic evaluations of this herd and second that included the maternal lineage effect as random effect. The maternal lineage was gotten tracing itself from a female, a line until the last female with register in the data base, considering she as a founder. Amongst the analyzed characteristics, the maternal lineage effect was significant (P < 0,05) only for weight weaning. For this characteristic, the maternal lineage effect was responsible for great alteration in the ranking of the 1000 better animals, as much for males and females. The variation of the maternal lineages can promote difference of more than 22 kg in the weight at weaning, corresponding to 12,9% of the phenotypic mean

Cytoplasmic incompatibility (CI) is an intriguing, widespread, symbiont-induced reproductive failure that decreases offspring production of arthropods through crossing incompatibility of infected males with uninfected females or with females infected with a distinct symbiont genotype. For years, the molecular mechanism of CI remained unknown. Recent genomic, proteomic, biochemical, and cell biological studies have contributed to understanding of CI in the alphaproteobacterium Wolbachia and implicate genes associated with the WO prophage. Besides a recently discovered additional lineage of alphaproteobacterial symbionts only moderately related to Wolbachia, Cardinium (Bacteroidetes) is the only other symbiont known to cause CI, and genomic evidence suggests that it has very little homology with Wolbachia and evolved this phenotype independently. Here, we present the first transcriptomic study of the CI Cardinium strain cEper1, in its natural host, Encarsia suzannae, to detect important CI candidates and genes involved in the insect-Cardinium symbiosis. Highly expressed transcripts included genes involved in manipulating ubiquitination, apoptosis, and host DNA. Female-biased genes encoding ribosomal proteins suggest an increase in general translational activity of Cardinium in female wasps. The results confirm previous genomic analyses that indicated that Wolbachia and Cardinium utilize different genes to induce CI, and transcriptome patterns further highlight expression of some common pathways that these bacteria use to interact with the host and potentially cause this enigmatic and fundamental manipulation of host reproduction. IMPORTANCE The majority of insects carry maternally inherited intracellular bacteria that are important in their hosts' biology, ecology, and evolution. Some of these bacterial symbionts cause a reproductive failure known as cytoplasmic incompatibility (CI). In CI, the mating of symbiont-infected males and uninfected females produces few or no daughters. The CI symbiont then spreads and can have a significant impact on the insect host population. Cardinium, a bacterial endosymbiont of the parasitoid wasp Encarsia in the Bacteroidetes, is the only bacterial lineage known to cause CI outside the Alphaproteobacteria, where Wolbachia and another recently discovered CI symbiont reside. Here, we sought insight into the gene expression of a CI-inducing Cardinium strain in its natural host, Encarsia suzannae. Our study provides the first insights into the Cardinium transcriptome and provides support for the hypothesis that Wolbachia and Cardinium target similar host pathways with distinct and largely unrelated sets of genes.