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

No description available.

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.

Ng, Sin Man. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 96-104). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Patients with giant axonal neuropathy (GAN) exhibit loss of motor and sensory function and typically live for less than 30 years. GAN is caused by autosomal recessive mutations leading to low levels of gigaxonin, a ubiquitously-expressed cytoplasmic protein whose cellular roles are poorly understood. GAN pathology is characterized by aggregates of intermediate filaments (IFs) in multiple tissues. Disorganization of the neuronal intermediate filament (nIF) network is a feature of several neurodegenerative disorders, including amyotrophic lateral sclerosis, Parkinson's disease and axonal Charcot-Marie-Tooth disease. In GAN such changes are often striking: peripheral nerve biopsies show enlarged axons with accumulations of neurofilaments; so called "giant axons." Interestingly, IFs also accumulate in other cell types in patients. These include desmin in muscle fibers, GFAP (glial fibrillary acidic protein) in astrocytes, and vimentin in multiple cell types including primary cultures of biopsied fibroblasts. These findings suggest that gigaxonin may be a master regulator of IFs, and understanding its function(s) could shed light on GAN as well as the numerous other diseases in which IFs accumulate. However, an interaction between gigaxonin and IFs has not been detected and how IF accumulation is triggered in the absence of functional gigaxonin has not been determined. To address these questions I undertook a proteomic screen to identify the normal binding partners of gigaxonin. Prominent among them were several classes of IFs, including the neurofilament subunits whose accumulation leads to the axonal swellings for which GAN is named. Strikingly, human motor neurons (MNs) differentiated from GAN iPSCs recapitulate this key phenotype. Accumulation of nIFs can be rescued by reintroduction of gigaxonin, by viral delivery or genetic correction. GAN iPS-MNs do not display survival vulnerability in the presence of trophic factors, but do display increased cell death in the presence of oxidative stress. Preliminary experiments suggest that in iPS-MNs nIFs are degraded by contributions from both the proteasome and lysosome. Gigaxonin interacts with the autophagy protein p62 which has been implicated in the clearance of ubiquitin aggregates by the lysosome, and this interaction is greatly enhanced in conditions of oxidative stress. My data provide the first direct link between gigaxonin loss and IF aggregation, and suggest that gigaxonin may be a substrate adaptor for the degradation of IFs by autophagy, pointing to future approaches for reversing the phenotype in human patients.

La morphogenèse épithéliale est essentielle à la formation des organes. J'utilise le follicule ovarien de Drosophila comme modèle d'étude de l’aplatissement des cellules. Un follicule est composé de cellules germinales en croissance entourées d'une monocouche de cellules épithéliales cuboïdes. À un stade de développement spécifique, une part de ces cellules s'aplatit en suivant une vague régulée. Cet aplatissement est en partie contrôlé par un gradient de pression provenant d’un groupe de cellules germinales (les cellules nourricières). Toutes les cellules germinales sont connectées via des ponts cytoplasmiques. Cette thèse étudie les mécanismes conduisant à la génération du gradient de pression, et à la modulation moléculaire induite par cette force mécanique pour permettre l'aplatissement. J'ai montré que le nombre et le diamètre des ponts cytoplasmiques influaient sur la pression. En utilisant des reconstructions tridimensionnelles de follicules, j’ai étudié le rôle de la croissance différentielle des cellules nourricières en mesurant le changement de volume des cellules germinales lors de l'aplatissement des cellules. Enfin, j’ai cherché le mécanisme moléculaire conduisant à l’aplatissement des cellules et influencé par un stimulus mécanique à partir de la pression germinale, en proposant un rôle de la voie Hippo dans ce processus. En conclusion, nous proposons que la croissance des cellules germinales influe de manière mécanique et génétique sur les cellules épithéliales pour permettre l’élongation, et donc l'acquisition de la forme finale du follicule. / Epithelial morphogenesis is essential for organ formation. I use the Drosophila ovarian follicle as a model for studying cell flattening. A follicle is composed of growing germ cells surrounded by a monolayer of cuboidal epithelial cells. At a specific stage of development, some of these cells flatten out following a regulated wave. This flattening is partly controlled by a pressure gradient from part of the germ cells (the nurse cells). All germ cells are connected via cytoplasmic bridges. This thesis studies the mechanisms leading to the generation of the gradient of pressure, and to the molecular modulation induced by this mechanical force to allow flattening. I have shown that the number and diameter of cytoplasmic bridges affect the pressure. Using three-dimensional reconstructions of follicles, I studied the role of differential growth of nurse cells by measuring the change in germ cell volume during epithelial cell flattening. Finally, I looked for the molecular mechanism leading to the flattening and influenced by a mechanical stimulus from the germinal pressure, supporting a role of the Hippo pathway in this process. In conclusion, we propose that germ cell growth mechanically and genetically influences epithelial cells to allow elongation, and thus the acquisition of the final form of the follicle.

No description available.

No description available.

Genetic variation exists in <i>Raphanus</i> that could be of use to <i>Brassica</i> breeders. Of particular interest is the Ogura system of cytoplasmic male sterility (CMS) which has been worked on extensively in a <i>Brassica napus</i> background. Problems have been experienced in <i>B. napus</i>restorer lines due to the inheritance of a large segment of <i>Raphanus</i> chromosome containing the fertility restoring locus. This restorer introgression is located on the <i>Brassica</i> C genome making it only of use for <i>B. napus</i> and not for <i>B. rapa</i> or <i>B. juncea</i>. This thesis describes the development of the materials necessary for the introgression into the <i>Brassica</i> A genome of a defined segment of <i>Raphanus</i> chromosome containing a restorer locus. Defined genetic stocks of <i>Raphanus</i> were developed that contained specific loci controlling restoration of Ogura CMS. This material was used to develop populations segregating for specific restorer loci. Extensive RFLP maps of three <i>Raphanus</i> populations were developed and aligned, resulting in a robust consensus map of the entire <i>Raphanus</i> genome. Three restorer loci were accurately mapped on three separate linkage groups. The segment of <i>Raphanus</i> that is implicated in the restoration of Ogura CMS in a <i>B. napus</i> restorer line developed by INRA was identified and it did not correspond to any of the regions containing the three mapped restorer loci, suggesting the presence of more restorer loci in <i>Raphanus</i>. Comparative mapping between the <i>Raphanus</i> genome map and previously generated <i>Brassica</i> A genome RFLP maps demonstrated large regions of collinearity between segments of chromosomes of the two species. Preliminary examination of the two genome maps suggest they contain essentially the same overall genetic content but with large segments of the genomes rearranged with respect to each other. Likely sites of <i>Raphanus</i> restorer introgression into the <i>Brassica</i> A genome were predicted. Trigenomic tetraploids were developed in which pairing and recombination between homoeologous segments of <i>Raphanus</i> and <i>Brassica</i> A chromosomes should result. Progeny of these individuals will allow an assessment of the pattern and extent of recombination that occurs between the chromosomes of the <i>Raphanus</i> and <i>Brassica</i> A genomes and should lead to the development of 'B. napus' lines carrying Ogura CMS restorer alleles from <i>Raphanus</i>.

Thesis (Ph. D.)--University of Missouri--Columbia, 2000. / "August 2000." Typescript. Vita. Includes bibliographical references (leaves 107-112). Also available on the Internet.