Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

Aflatoxin B₁ (AFB₁) is a mold-produced toxin which has been shown to be a potent hepatocarcinogen in many animal species. Of the species studied thus far, rainbow trout have proven to be the most sensitive. Experiments were conducted to investigate various aspects of AFB₁ metabolism in this species, including in vitro mutagenesis, and effects of dietary modifiers of AFB, carcinogenesis on in vitro metabolism and mutagenesis. A comparative study of AFB₁ metabolism in two salmonid species was also conducted. In the first study, the relative mutagenic potencies of several alfatoxin metabolites were evaluated using a trout liver fraction system. Preliminary studies characterizing trout liver fractions for use as an activation system were described. The results from comparative mutagenicity experiments demonstrated that in vitro mutagenic potencies qualitatively correlated with the in vivo carcinogenic activities of various aflatoxins in rainbow trout. The importance of these findings is discussed. In the second study fish hepatocytes were characterized to examine possible differences in activation of AFB₁ to bacterial mutagens by hepatocytes from rainbow trout and coho salmon, two species which are known to differ markedly in sensitivity to the carcinogenic effects of AFB₁. Activation efficiency was approximately three times greater in hepatocytes from trout compared to salmon. A more marked difference was seen when S20 liver fractions from the two species were used. Analysis of unbound [³H]AFB₁ metabolites revealed that trout hepatocytes metabolized [³H]AFB₁ to a greater extent than salmon. The results accurately reflected in vivo carcinogenesis trends in salmonid fish. Additional experiments were conducted to evaluate the effects of dietary modifiers of AFB₁ carcinogenesis on in vitro mutagenesis and metabolism of AFB₁. Dietary β-naphthoflavone (β-NF) was shown to induce the production of a novel trout metabolite of AFB₁, aflatoxicol M₁ (AFL-M₁). AFL-M₁ exhibited a mutagenic potency less than AFB₁ or aflatoxicol (AFL), but greater than that of aflatoxin-M₁ (AFM₁). Dietary β-NF, however, appeared to have no effect on in vitro mutagenic activation of AFB₁ using hepatocytes or liver S20 fraction from trout. Dietary PCBs (Aroclor 1254) was shown to significantly decrease in vitro mutagenesis of AFB₁, which reflected a similar PCB-mediated inhibitory effect on AFB₁ carcinogenesis in trout in vivo. Cyclopropenoid fatty acids (CPFAs) present in the diet (0-600 ppm) were shown to have no effect on in vitro mutagenesis of AFB₁, indicating CPFAs may not significantly alter in vivo initiation of AFB₁ carcinogenesis. / Graduation date: 1983

Triplicate groups of rainbow trout (Salmo gairdneri) fed six diets; five based on fish protein concentrate (FPC) ranging in caloric density from 4.36 to 6.19 kcal/g, and one based on vitamin free casein with a caloric density of 5.26 kcal/g were evaluated with respect to diet ingredient utilization. The parameters used to evaluate efficiency of diet utilization were: feed conversion, energy and protein conversion, and growth. The desirability of the edible portion of the fish produced on the different treatments from a flavor and texture standpoint was determined. The protein level was maintained at 38% of the dry diet, with 7.8% supplied by gelatin and the remainder by either FPC or casein. The herring oil levels of the diets ranged from 25% to 45% of the dry diet, and was the primary source of calories. Alpha-cellulose was included as a filler and ranged from 12.2% to 31.2% of the dry diet. The FPC based diets produced statistically superior weight gains when compared to the casein based diet. The efficiency of feed conversion was improved as the level of herring oil was increased. The energy and protein conversions were relatively constant for the FPC based diets, with the casein based diet being lower (P < 0.05). / Graduation date: 1975

The fundamental objective of this analysis was to isolate and identify the factors governing the demand for domestically produced rainbow trout in a representative west coast market, and assess the impact on that demand, if any, of the introduction of pansize salmon. The approach taken in this market demand study was to identify those variables hypothesized to determine supply and demand for rainbow trout. Several testable hypotheses concerning the anticipated relationships were specified. It was hypothesized that a negative relationship would exist between the price of trout at the brokerage level and the quantity demanded at that level. Conversely, the price of trout at the wholesale level was hypothesized to be positively correlated with the quantity of rainbow trout demanded at the brokerage level. Further, the signs on the coefficients of variables accounting for the wholesale prices of substitute items were expected to be negative, while comparable prices at the brokerage level should be positive, based upon the hypothesis. It was hypothesized that the presence of Japanese trout in the market place would have a negative impact on the quantity of domestically produced trout demanded. Personal disposable income was hypothesized to be positively correlated with the quantity of trout demanded. Expectations were that seasonal factors tend to cause trout demand to fluctuate cyclically. An econometric simultaneous equations model was specified from which estimates of the parameters of the demand equation were obtained using Two Stage Least Squares techniques. A recognition of the limitations associated with the available data set necessitates the emphasizing of the preliminary nature of these results. Data on quantities and prices of rainbow trout and equivalent price series for hypothesized substitutes were obtained through personal interviews with market participants and close observers thereof. The results of the study, while preliminary, tend to support the original set of hypotheses concerning the interrelationships between quantity of domestic trout demanded and own-price, the price of close substitutes and seasonal demand fluctuations. Somewhat unexpectedly, the regression seems to have uncovered a negative income/quantity demanded relationship for rainbow trout. This raises some interesting questions which might best be addressed in terms of hypotheses for future analysis. / Graduation date: 1977

Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (March 1, 2007) Vita. Includes bibliographical references.

No description available.

Graduation date: 1973

Thesis (M.S.)--Northern Michigan University, 2008. / Bibliography: leaves 66-73.

Thesis (Ph. D.)--University of Michigan, 1937. / Thesis note on label attached to p. 203. "Reprinted from volume 66 (1936) Transactions of the American Fisheries Society." "Literature cited": p. 210.

Thesis (Ph. D., Animal Physiology)--University of Idaho, June 2009. / Major professor: Ronald W. Hardy. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.