Date of Award

2022

Document Type

Thesis

Degree Name

Master of Science (M.S.)

Department

Biological Sciences

First Advisor

Jane I. Khudyakov

First Committee Member

Michael Tift

Second Committee Member

Zachary Stahlschmidt

Abstract

Marine mammals such as northern elephant seals (NES) routinely experience hypoxemia and ischemia-reperfusion events to many tissues during deep dives with no apparent adverse effects. Adaptations to diving include increased antioxidants and elevated oxygen storage capacity associated with high hemoprotein content in blood and muscle. Despite experiencing decreased oxygen tensions during diving, NES likely rely on the mobilization of large lipids stores and catabolism of fatty acids to provide energy to exercising muscle while diving. To identify potential regulatory mechanisms that may underly hypoxia and exercise tolerance in diving mammals, this study used system-wide approaches to characterize changes in genes and proteins in two metabolically active tissues (skeletal muscle and blubber) and whole blood of NES over development and in response to translocation. Specifically, this study profiled muscle and blood gene expression associated with regulation of oxidative stress and inflammatory pathways in weaned pups, juveniles, and adult NES as well as evaluated muscle and blubber transcriptomic and proteomic responses to swimming and diving in juvenile NES. I found that expression of genes associated with mitochondrial biogenesis (PGC1A, ESRRA, ESRRG), immune system activation (HMOX2, IL1B, NRF2, BVR, IL10), and protection from lipid peroxidation (GPX4, PRDX6, PRDX1, SIRT1) increased over postnatal development in muscle and whole blood of NES, providing a potential ontogenic mechanism for increasing diving capacity and hypoxia and ischemia-reperfusion tolerance. I also found that expression of genes and abundance of proteins associated with lipid transport (APOD, ABCA6, ABCA8, ABCA10, CD1E), lipid catabolism (ADIPOQ , ENPP6), and adipogenesis (DLK1, ADIRF,) increased, while those associated with insulin sensitivity and energy expenditure (APLN, VGF) decreased in response to swimming and diving in juvenile NES blubber and muscle, suggesting potential mechanisms for fuel provisioning to muscle during exercise in hypoxic conditions. Together, these data provide insights into gene activity in muscle, blubber, and blood cells that may provide hypoxia tolerance and regulate energy homeostasis and exercise performance during breath holds in diving mammals.

Pages

109

Share

COinS