Date of Graduation

Spring 2021


Master of Science in Biology



Committee Chair

Kyoungtae Kim


The primary focus of my research was to obtain global gene expression profiles of baker’s yeast exposed to sub-lethal doses of nanoparticles, such as silver nanoparticles (AgNPs), yellow- emitting CdSe/ZnS quantum dots (QDs), green-emitting CdSe/ZnS QDs, and InP/ZnS QDs, to reveal novel insights on their unique mechanisms of toxicity. Despite their diverse applications, their long-lasting effects on the environment and human health are not well understood. To assess their toxicity, I administered experiments that exposed Saccharomyces cerevisiae to a variety of nanoparticles and measured cell viability, ROS levels, and changes in gene expression. Most notably, I used RNA-sequencing (RNA-seq) to identify gene identities of differentially expressed genes (DEGs) in nanoparticle-treated cultures. I found AgNPs altered genes implicated in rRNA processing, ribosome biogenesis, cell wall/cell membrane structure, and mitochondrial functions, yellow-emitting CdSe/ZnS QDs altered genes implicated in RNA processing, translation, oxidation-reduction, transmembrane-transport, and the ETC, green- emitting QDs altered genes implicated in translation, protein metabolic processes, transmembrane transport, cellular homeostasis, and cell wall organization, and InP/ZnS QDs altered genes associated with oxidation-reduction, transmembrane-transport, metal ion homeostasis, translation, and protein compound metabolic processes. Nevertheless, I concluded that all tested nanoparticles exerted some sort of cytotoxic effect by disrupting normal cellular functions of the budding yeast.


AgNPs, CdSe/ZnS, InP/ZnS, QDs, gene expression, RNA-seq, DEGs, Saccharomyces cerevisiae

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© Cullen M. Horstmann

Open Access