Date of Award

Spring 5-24-2015

Document Type

Undergraduate Honors Thesis

Degree Name

Bachelor of Arts in Biology




Dr. Sue Lowery


Dr. James Gump


California Yellowtail muscle fibers have been observed to exhibit two drastically different development patterns resulting from the speeds at which they are exercised. When fish are exercised at a moderate rate their epaxial fast-twitch muscle fibers grow in diameter—hypertrophy; when they are exercised at a fast speed, more new epaxial fast-twitch muscle fibers are produced—hyperplasia. To determine the underlying reason for this difference in muscle development, my summer research project and honors thesis exercised fish at: fast, moderate, and control speeds for a sustained amount of time to determine what is happening on a cellular level to cause the observed differences. Specifically, I am interested in the role of both IGF and HIF transcription factors in influencing the hyperplasia observed after sustained, high-speed exercise. My hypothesis is that an oxygen debt is incurred in the white muscle fibers and this leads to hypoxic conditions in the tissue. If HIF is found to be present in larger quantities in the tissues of fish that swam at fast speeds as opposed to the control and moderate speeds, it would suggest that there are very low levels of oxygen in the muscle fibers and that the HIF transcription factor is influencing various biochemical signaling pathways to induce a hyperplastic response.