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Characterization of modes and kinetics of mutation accumulation in Saccharomyces cerevisiae through the analysis of defined cellular lineages

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dc.contributor.authorStewart, Joseph, author
dc.contributor.authorArgueso, Juan Lucas, advisor
dc.contributor.authorMoreno, Julie, committee member
dc.contributor.authorRegan, Daniel, committee member
dc.contributor.authorWiese, Claudia, committee member
dc.date.accessioned2024-09-09T20:52:03Z
dc.date.available2025-08-16
dc.date.issued2024
dc.description.abstractIn the field of evolution, gradualism is the process of incremental adaptation supported by a slow and random accumulation of mutations that, over time, lead to genetic diversification and fitness gains. Although this Darwinian model is well supported and widely accepted, it cannot always explain the rapid changes seen in some instances such as tumors with extremely high and complex mutation loads. Recent reports in various organisms, including from our group using Saccharomyces cerevisiae, provide evidence for an additional mode of rapid and non-independent accumulation of chromosomal rearrangements. We have used a yeast model to follow the accumulation of structural genomic rearrangements such as loss of heterozygosity (LOH). We found that while chances of a single LOH event happening are very low, two or more LOH tracts co-occurred at rates 25- to 200-fold higher than expected if these events were independent of each other; therefore, the conventional process of slow and independent accumulation of mutations are not sufficient to account for every change in the genome. In the present study, we focused on temporal kinetics of bursts of LOH accumulation in yeast. We developed a hybrid diploid yeast experimental strain that enables identification of LOH event both through counter-selection and visual screening for colony color. This hybrid strain, made from the S288c and SK1 genetic backgrounds, possesses ~55,000 heterozygous SNPs distributed throughout the genome and allows for ease of tracking LOH events through sequencing. The screening approach was used in combination with microcultures (one cell grown for 5 or 6 divisions) in phylogenetic analyses that unambiguously revealed 18 cases where multiple LOH events co-occurred in the same cell division cycle. Collectively, these studies offer support for punctuated bursts of mutation accumulation caused by systemic genomic instability (SGI). Additionally, we have investigated a potential mechanism that influences SGI, namely global noise in gene expression.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierStewart_colostate_0053A_18410.pdf
dc.identifier.urihttps://hdl.handle.net/10217/239216
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2020-
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.rights.accessEmbargo expires: 08/16/2025.
dc.titleCharacterization of modes and kinetics of mutation accumulation in Saccharomyces cerevisiae through the analysis of defined cellular lineages
dc.typeText
dcterms.embargo.expires2025-08-16
dcterms.embargo.terms2025-08-16
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCell and Molecular Biology
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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