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Alexander van Oudenaarden. Acar, Murat Massachusetts Institute of Technology. Dept. of Physics. Massachusetts Institute of Technology. Department of Physics 2009-04-29T17:38:02Z 2009-04-29T17:38:02Z 2007 2007 http://hdl.handle.net/1721.1/45411 317619986 Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007. Includes bibliographical references (p. 97-104). Cellular genetic information is encoded in DNA. The passage of this information from DNA to proteins is regulated at multiple levels and each level gives cells the chance to control the structure and function of their components. Transcriptional regulation is an important part of this multi-level process. By using feedback loops as part of transcriptional gene networks, cells can tune the level and stability of gene expression. In the first half of my thesis, I will discuss how isogenic cells can be re-programmed to have varying levels of memory associated with previous growth conditions and how genetic noise limits the stability of this cellular memory. Noise in gene expression, through the phenotypic heterogeneity it promotes, has the potential to be a mechanism implemented by cells to cope with the uncertainties in environmental conditions. By randomly expressing multiple phenotypes, each fit to a certain environment, cells can survive unexpected changes in the extracellular environment. In this way, a population can hedge its bets against environmental uncertainty. Depending on how often the cells choose to display various phenotypes, the population can range from being highly diverse (heterogeneous) to being less diverse (homogeneous). In the second half of my thesis, I will discuss how the degree of phenotypic diversity for an isogenic population of cells can be tuned by re-engineering a gene network. I will present results from experiments which test the effect of noise-induced diversity on population fitness in the presence of fluctuating environments. The results demonstrate that for an optimum population growth in fluctuating environments, cells need to match the rates of inter-phenotypic switching to the frequency of environmental changes. by Murat Acar. Ph.D. 104 p. eng Massachusetts Institute of Technology 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. http://dspace.mit.edu/handle/1721.1/7582 Physics. Feedback regulation in gene networks Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="4c97f846-9825-4a30-867c-f10eb0d32a52"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Feedback regulation in gene networks</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2007</PublicationDate> <Authors> <Author> <DisplayName>Acar, Murat</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Physics.</Keyword> <Abstract>Cellular genetic information is encoded in DNA. The passage of this information from DNA to proteins is regulated at multiple levels and each level gives cells the chance to control the structure and function of their components. Transcriptional regulation is an important part of this multi-level process. By using feedback loops as part of transcriptional gene networks, cells can tune the level and stability of gene expression. In the first half of my thesis, I will discuss how isogenic cells can be re-programmed to have varying levels of memory associated with previous growth conditions and how genetic noise limits the stability of this cellular memory. Noise in gene expression, through the phenotypic heterogeneity it promotes, has the potential to be a mechanism implemented by cells to cope with the uncertainties in environmental conditions. By randomly expressing multiple phenotypes, each fit to a certain environment, cells can survive unexpected changes in the extracellular environment. In this way, a population can hedge its bets against environmental uncertainty. Depending on how often the cells choose to display various phenotypes, the population can range from being highly diverse (heterogeneous) to being less diverse (homogeneous). In the second half of my thesis, I will discuss how the degree of phenotypic diversity for an isogenic population of cells can be tuned by re-engineering a gene network. I will present results from experiments which test the effect of noise-induced diversity on population fitness in the presence of fluctuating environments. The results demonstrate that for an optimum population growth in fluctuating environments, cells need to match the rates of inter-phenotypic switching to the frequency of environmental changes.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>