In this thesis, we examined the effects of the exposures to anthropogenic pollutants on the fish, primarily juvenile chinook salmon, immune system using newly and recently developed immune assays. In addition, we developed a new assay for measuring immunocompetence of fish. In the first chapter, the Alamar Blue assay was developed to quantify the proliferation of chinook salmon (Oncorhynchus tshawytscha) leukocytes. Isolated splenic and pronephric leukocytes were stimulated with different concentration of mitogens (LPS, PWM, and ConA) for various incubation times. Optimum cell culture conditions (cell density, mitogen concentration, and incubation time) for the Alamar Blue assay were evaluated by comparison with flow cytometric analysis. The Alamar Blue dye was non-toxic for leukocytes, and the assay proved to be able to quantify the mitogenic responses using LPS, but PWM and ConA. In the second chapter, we determined the effects and mechanisms by which p, p'- DDE exposure might affect the immune system of chinook salmon (Oncorhynchus tshawytscha). Isolated salmon splenic and pronephric leucocytes were incubated with different concentrations of p, p'-DDE, and cell viability, induction of apoptosis, and mitogenic responses were measured by flow cytometry and Alamar Blue assay. p, p'- DDE significantly reduced cell viability and proliferation and increased apoptosis. The effect of p, p'-DDE on pronephric leukocytes was more severe than on splenic leukocytes, likely because pronephric leucocytes had a higher proportion of granulocytes, cells that appear more sensitive to p, p'-DDE. The effect of p, p'-DDE on leucocytes appeared to vary between developmental stages or season. The mitogenic response of leukocytes of chinook salmon exposed to p, p'-DDE in vivo exhibited a biphasic dose-response relationship. Only leukocytes isolated from salmon treated with 59 ppm p, p'-DDE had a significantly lower percentage of Ig+ blasting cells than controls. Our results support the theory that exposure to chemical contaminants could lead to an increase in disease susceptibility and mortality of fish due to immune suppression. In the third chapter, we evaluated the direct effects of in vitro exposures to tributyltin (TBT), widely used biocide, on the cell mediated immune system of chinook salmon (Oncorhynchus tshawytscha). Splenic and pronephric leukocytes isolated from juvenile chinook salmon were exposed for 6, 24, or 96 hr to a concentration range of 0.03 0.1 mg TBT 1−1 in cell cultures. Effects of TBT on cell viability, induction of apoptosis, and mitogenic responses were measured by flow cytometry. Splenic and pronephric leukocytes in the presence of TBT experienced a concentration-dependent decrease in the viability in cell cultures following the induction of apoptosis. In addition, pronephric lymphocytes exhibited a greater sensitivity to TBT exposure than pronephric granulocytes. The functional ability of splenic B-cells to undergo blastogenesis upon LPS stimulation was also significantly inhibited in the presence of 0.05, 0.07, or 0.10 mg 1−1 of TBT in the cell cultures. Flow cytometric assay with the fluorescent conjugated monoclonal antibody against salmon surface immunoglobulin was employed for the conclusive identification of B-cell in the chinook salmon leukocytes. Our findings suggest that adverse effects of TBT on the function or development of fish immune systems could lead to an increase in disease susceptibility and its subsequent ecological implications.

Fish Physiology: Organic Chemical Toxicology of Fishes discusses the different types of organic chemical contaminants and their respective toxic effects in fish. The book also covers the detection of dissolved organic compounds and methods to assess organic toxicity. Substances addressed in this book include organometallics, hydrocarbons, endocrine disrupting compounds (EDCs), insecticides, herbicides, and pharmaceuticals. Fish are exposed to an ever-increasing array of organic chemicals that find their way into rivers and oceans. Some of these compounds are no longer being produced but nonetheless persist within the environment (persistent organic pollutants, or POPs). The exposure of fish to toxic organic compounds has potential impact on human, fish, and ecosystem health. Yet the regulations that govern environmental water quality vary worldwide, and compliance is never complete. This book provides a crucial resource on these issues for researchers in zoology, fish physiology, and related fields; applied researchers in environmental monitoring, conservation biology, and toxicology; and university-level students and instructors in these areas. - Organized by type of toxic organic chemicals - Includes metals, POPs, EDCs, herbicides, insecticides, and pharmaceuticals - Measures toxicity in a variety of ways aside from lethality - Probes the toxic effects of compound mixtures as well as single pollutants