Past Members of our Tuna Center Team!
Dr. David Marcinek, a former Ph.D student in the lab focused on examining the structural and functional aspects of tuna myoglobin for his thesis research. This has led to the development of assays for isolating and assessing myoglobin primary structure, and concentration along with molecular examination of the protein structure. Myoglobin is a monomeric respiratory protein that reversibly binds oxygen. The primary function of myoglobin is the facilitated diffusion of oxygen from the sarcolemma to the mitochondrial oxygen sink. All tunas and in particular bluefin tuna, have relatively high concentrations of myoglobin in both their slow and fast-twitch muscle associated with higher aerobic capacities of these tissues. It has long been known that high concentrations of myoglobin are associated with the higher aerobic capacities across a wide spectrum of animals but the relationship between myoglobin and aerobic capacity within individuals is less clear.
Ellen V. Freund, Ph.D. recently finished her Ph.D in the lab which focused on metabolism and cardiac physiology of the bonitos and yellowfin tuna. Measurement of metabolic rate in bonitos revealed that high metabolism, a characteristic of true tunas, was present in the more ancestral ectothermic lineage. Ellen examined the properties of the ventricular muscle of yellowfin tuna and was the first to demonstrate that the cardiac cells of this portion of the heart were temperature sensitive. She also examined the effect of calcium ions on heart function in cardiac strips from the tunas.
The elevated temperature of the slow-twitch swimming muscle in bluefin tuna establishes a temperature gradient between the deepest parts of the muscle and the muscle at the surface of the body. John Altringham of the University of Leeds and Barbara Block collaborated in 1997 to demonstrate the importance of warming the muscle for power generation. They also found regional heterogeneity of physiological characteristics in this swimming muscle associated with the temperature gradient. Dr. Althingham’s Ph.D student, Mr. David Ellerby, recently completed a similar study investigating how bonito muscle functions and their swimming biomechanics.
