Document Type

Thesis

Date of Degree Completion

Spring 2022

Degree Name

Master of Science (MS)

Department

Chemistry

Committee Chair

Carin Thomas

Second Committee Member

Derek Ricketson

Third Committee Member

April Binder

Abstract

Mitochondria are cellular organelles that are becoming more recently studied. One of their main functions is the production of energy through cellular respiration, which is crucial to cell life. However, they are also associated with numerous disease states. It is hypothesized that reactive oxygen species (ROS), largely produced in mitochondria, induce oxidative stress and affect mitochondrial morphology along with cell viability. This study compares chemical exposure of menadione, an ROS producer, and phthalates (plasticizers) on two mouse hepatocyte cell lines to determine the effects they have on mitochondrial morphology and cell viability. Three experiments were performed to analyze the effects of chemical exposure: 1) WST-8 cell viability assays, 2) Cell ROX Green ROS evaluations, and 3) fluorescent mitochondrial membrane visualization. Taken together, it was determined that increased ROS production, caused by chemical exposure, influenced alterations in mitochondrial membrane structure and caused lower cell viability. Low concentrations of menadione caused the mitochondrial networks to emit a speckled fragmented phenotype, while the high concentrations instead caused an increased absence of mitochondrial fluorescent dye, possibly due to loss of mitochondrial membrane potential. The phthalate, DEHP, was not shown to be toxic to the cells, and mitochondrial phenotypes that were displayed after this chemical exposure were similar to those observed without chemical exposure. The DEHP metabolite, MEHP, was found to produce ROS at some concentrations tested, but not all. It was observed that chemicals causing increased production of ROS, first caused mitochondrial fusion, and then speckled fragmentation as high chemical concentrations were reached. It was also observed that mitochondrial swelling occurred throughout all tested cells, whether chemically exposed or not. As swelling or speckling of the mitochondrial networks increased, fusion decreased along with cell viability. This shows that mitochondrial morphology and cell viability can be highly affected by chemical exposure and may also have an effect on one another.

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