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Abstract
Induction of triploidy (containing an additional set of chromosomes) is utilized in salmonid aquaculture to produce a sterile fish. Sterility in salmonids prevents mating with wild stocks and confers the potential for higher growth rates; however, previous research suggests triploid salmonids show reduced performance (i.e. poorer growth and higher mortalities) when reared in suboptimal conditions, like high temperature or low oxygen environments. The physiological underpinnings of this differential performance between diploid and triploid fish is not understood but may be related to cell size. Triploid fish have larger cells to accommodate their larger genome, but consequently contain fewer cells per volume of tissue. A larger cells size results in a reduced cellular surface are to volume ratio (SA:V), which can impact biological process that rely on diffusion. For example, aerobic metabolism relies on the diffusion of oxygen and the stress response relies on the diffusion of signaling molecules. The goal of my dissertation research was to investigate the relationship between cellular SA:V and physiological performance, specifically in triploid white surgeon. The results from my dissertation indicate that diploid and triploid white sturgeon are physiologically distinct, although many of the measured differences between ploidies appear minor. The primary distinctions between ploidies are metabolism and growth. This dissertation provides evidence that a reduction in cellular SA:V in triploid sturgeon limits aerobic metabolism at the cellular and whole organism level, ultimately reducing energy available for growth. Comparisons of diploid and triploid sturgeon differ from the literature comparing diploid and triploid salmonids; thus, any new triploid species should be researched before being incorporated into stocks by producers and hatcheries. Overall, this research not only provides insight in the basic science of the relationship between cell size and whole animal physiological performance, but also supplies caviar producers with key information for ploidy screening and management.
