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Physicochemical characterization of immortal strand DNA

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dc.contributor.advisor James L. Sherley. en_US
dc.contributor.author Lansita, Janice A. (Janice Ann), 1975- en_US
dc.contributor.other Massachusetts Institute of Technology. Biological Engineering Division. en_US
dc.date.accessioned 2005-06-02T19:43:48Z
dc.date.available 2005-06-02T19:43:48Z
dc.date.copyright 2004 en_US
dc.date.issued 2004 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/18038
dc.description Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2004. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract Adult tissue differentiation involves the generation of distinct cell types from adult stem cells (ASCs). Current understanding of tissue differentiation mechanisms is based on studies of protein and RNAs that asymmetrically segregate between daughter cells during embryogenesis. Whether or not other types of biomolecules segregate asymmetrically has not been widely studied. In 1975, John Cairns proposed that ASCs preferentially segregate the oldest parental template DNA strands to themselves and pass on newly replicated DNA strands to their differentiating progeny in order to protect the stem cell from inheriting DNA replication mutations. This laboratory has shown non-random chromosome segregation in murine fetal fibroblasts that model asymmetric self-renewal like ASCs. In these cells, chromosomes that contain the oldest DNA strands co-segregate to the cycling daughter stem-like cells, while chromosomes with more recently replicated DNA segregate to the non-stem cell daughters. Previously, cytological methods were reported to elucidate non-random segregation in these cells. This dissertation research provides additional confirmation of the mechanism using physicochemical methods. Specifically, buoyant density-shift experiments in equilibrium CsCl density gradients were used to detect co-segregated "immortal DNA strands" based on incorporation of the thymidine base analogue bromodeoxyuridine. In addition, DNA from cells undergoing non-random mitotic chromosome segregation was analyzed for unique DNA base modifications and global structural modifications (by HPLC and melting temperature analyses). To date, these studies show no significant differences compared to control randomly segregated DNA. Components of the mitotic chromosome separation en_US
dc.description.abstract (cont.) apparatus that might play a role in the co-segregation mechanism were also evaluated. Two homologous proteins, essential for proper chromosome segregation and cytokinesis, Aurora A kinase and Aurora B kinase, were highly reduced in expression in cells retaining immortal DNA strands and may indicate a role for them in the immortal strand mechanism. These studies independently confirm the immortal strand mechanism and provide methods for its detection in other cell lines. In addition, observed changes in chromosome segregation proteins that are potential candidates for involvement in the mechanism have revealed a new area of investigation in the laboratory. These findings are relevant to understanding normal tissue development, cancer, and aging. en_US
dc.description.statementofresponsibility y Janice A. Lansita. en_US
dc.format.extent 129 leaves en_US
dc.format.extent 7193524 bytes
dc.format.extent 7210394 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582
dc.subject Biological Engineering Division. en_US
dc.title Physicochemical characterization of immortal strand DNA en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Biological Engineering Division. en_US
dc.identifier.oclc 57350867 en_US


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