First Advisor

Jason Podrabsky

Term of Graduation

Spring 2026

Date of Publication

6-3-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.) in Biology

Department

Biology

Language

English

Subjects

Anoxia, Austrofundulus limnaeus, Cell Cycle Regulation, DNA Damage & Repair

Physical Description

1 online resource (viii, 87 pages)

Abstract

When exposed to the complete loss of oxygen (anoxia) most organisms undergo rapid cellular deterioration driven by a range of metabolic dysfunctions associated with the loss of the terminal electron acceptor for aerobic respiration. This loss of ability to create and maintain necessary levels of cellular ATP through oxidative phosphorylation contributes to loss of membrane potentials, increase in the accumulation of acidic by-products of anaerobic metabolism, and a decrease in the ability to support other molecular processes that rely on a steady supply of ATP. While this extreme oxygen stress is lethal to a majority of vertebrate organisms there are a handful of remarkable species that can withstand extended periods of complete anoxia and return to normal function after reoxygenation. The core response allowing for anoxic survival is a coordinated depression of metabolism, allowing for a balance of ATP supply and demand. Anoxia tolerance also requires tolerance of large bursts of reactive oxygen species associated with metabolic shifts during anoxic exposure and reoxygenation. These ROS bursts can damage various cellular components, including creating DNA lesions that can lead to increased secondary DNA damage and mutational burden if not repaired. This creates an interesting relationship between cells needing to limit ATP consumption to survive anoxia but simultaneously needing to expend ATP to repair increased oxidative damage. Embryos of the annual killifish Austrofundulus limnaeus have the strongest anoxia tolerance of any vertebrate making them an excellent model to investigate a functional relationship between stressed metabolism and DNA repair and replication.

Using a continuous cell line isolated from embryos of A. limnaeus, I employ cell biological techniques, including quantitative-image based cytometry, live cell imaging, long-amplicon qPCR, and assays to measure ATP and dNTP levels, to study the link between the bioenergetic status of anoxic cells, and their ability to progress through the cell cycle. Through this work I found that cellular proliferation continues through the initial days of anoxic exposure, with the core DNA damage response enzyme ATR being required for this continued anoxic cell proliferation. Remarkably, even with a large increase in ROS during anoxic exposure, there is no detectible increase in DNA damage during anoxia and reoxygenation in both the nuclear and mitochondrial genomes. The ability to maintain faithful DNA replication and repair of oxidative damage appears to be supported by a strong maintenance of cellular ATP levels and an increase in the production of dNTPs during anoxia. This research provides insight into the relationship between shifts in metabolism and the ability to maintain a stable genome and how this relationship is vital for anoxia tolerance in embryos of annual killifish.

Rights

© 2026 Riley Asa Roth-Carter

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. 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).

Persistent Identifier

https://archives.pdx.edu/ds/psu/44977

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