Abstract available in The FASEB Journal.

Life history within a single species can vary significantly. Many of these differences are associated with varying environmental conditions. Understanding what environmental conditions cue alternate life histories within a single species has been researched extensively. In salmonid fishes, more than almost any other group, varying environmental conditions give rise to individuals within species that take markedly different life history trajectories. Oncorhynchus mykissis a species of salmonid native to the Pacific Northwest region of North America. This species has two life history forms, anadromous and resident. The anadromous form spends a portion of its life in ocean while the resident life history form completes its entire life history in freshwater. Until the decision to migrate and morphological changes associated with smoltification occur, the two life history variants of this species are indistinguishable from each other. This ambiguity in juvenile O. mykiss morphology presents challenges for conservation managers charged with protecting and increasing threatened O. mykiss populations around the Pacific Northwest because conservation efforts cannot be evaluated until juvenile fish make the decision to migrate. Microarray gene expression analysis was used to profile gene expression in juvenile populations of wild and hatchery O. mykiss to identify gene expression variation associated with alternate life history variants. This analysis identified 8 DNA sequences present in both brain and gill tissues that differ in expression in rainbow trout and steelhead hatchery stocks. Differential expression as quantified by microarrays was validated with quantitative real-time PCR. Lastly, the expression of these putative life history markers was preliminarily evaluated in a wild population of O. mykiss at sample locations in the South Fork John Day River Basin, Oregon with known ratios of juvenile anadromous and resident fish.

Investigations of effects of starvation and time at stocking on the survival of catchable rainbow trout in two areas of Mammoth Creek in Dixie National Forest, Utah, were conducted from May 24 to December 6, 1969. Fish were starved for 6 days and 1 day and stocked in the morning (5:40-7:00 a.m.) and in the afternoon (1:45-5:30 p.m.). Out of 7,000 tagged fish stocked, 4,751 tags were returned by fishermen. The 6-day starved fish, stocked in the morning returned to the creel in highest numbers (1,240); followed by 1-day starved, afternoon-stocked fish (1,194); 6-day starved, afternoon-stocked fish (1,163); and 1-day starved, morning-stocked fish (1,154). For the entire stream, the main effects of starvation and time at stocking were not significant at the 10 percent level, but their interaction was significant at the 1 percent level. In the upper area, however, both 6-day starved lots returned to the creel in greater numbers (692) than the 1-day starved lots (643), and the main effect of starvation was significant at the 1 percent level in addition to the interaction being significant at the 5 percent level. About 81 percent of the tags returned were from fish caught in the sections stocked. One percent of the tags were from fish that moved upstream and 18 percent from fish that moved approximately 3 miles or less downstream. No consistent downstream movement patterns were related to either starvation or time at stocking. One week after the fishing season, 68 percent of all (19) tagged fish captured by electrofishing were 6-day starved fish, but this difference was not significant at the 10 percent level.

In the past few years the Utah Fish and Game Department, as well as the fish and game departments of other states, has been spending fisheries money for fish eradication on both lakes and streams. The Utah Fish and Game Department recently suggested to the University that research be initiated on the subject of toxaphene as a fish poison. Consequently, a better insight into conditions that exist for a given water type could be developed. To date there is a very small amount of material written on toxaphene. This is due primarily to the fact that toxaphene was not developed until the 19hO's. Toxaphene is used mainly as an insecticide. Such crops as tomatoes, beans, alfalfa, clover and cotton are protected by the use of toxaphene (Hudd and Genelly, 1956).

Users of the Instream Flow Incremental Methodology CTFIM) commonly assume that there is a positive linear relationship between available habitat (WUA) and stream fish biomass. However, several studies have shown a lack cf correlation between WUA and biomass. Such poor relationships may occur if other factors limit fish abundance. Food availability is a potentially important factor limiting abundance of stream fishes and can affect blomass by influencing fish condition (individual weight). I collected rainbow trout (Oncorhynchus mykiss) exposed to different levels of invertebrate-drift density to determine if condition was greater where food was more abundant. I also examined whether size-selective predation and gut fullness varied with drift density. Size-selective predation was not related to drift density. However, condition and gut fullness were both significantly correlated with drift density. Furthermore, changes in drift density appeared to have a stronger influence on small-trout condition than large-trout condition. The results of this study and others support the contention that the reliability of the IFIM might be improved if food availability were incorporated into models.

Chlorophyllin (CHL), a water-soluble derivative of the green plant pigment, chlorophyll, is an effective antimutagen and anticarcinogen in various model systems when used as a modulator against a class of carcinogens that, in general, have a structure consisting of at least three fused rings. Dibenzo[a,l]pyrene (DBP), an extremely potent environmental carcinogen, has been isolated from urban air samples, tobacco smoke, and coal smoke condensate. A study was conducted to evaluate the complex interrelationships among dietary DBP doses with co-exposure to a range of CHL doses. In order to achieve adequate statistical power in the generation of multiple dose-response curves, this dose-dose matrix experiment utilized over 12,000 rainbow trout. The resulting DNA adducts were assessed and evaluated as biomarkers of exposure to discern their relationship with the final tumor outcome. CHL was highly effective in reducing DBP-initiated DNA adduct formation in the liver and stomach and strongly inhibited tumor formation in the liver (56-79% inhibition), stomach (30-68%), and swim bladder (over 80% at the highest DBP dose). Molecular dosimetry revealed adduct formation to be predictive of final tumor response in both organs regardless of CHL dose. Other parameters evaluated were consistent with CHL-mediated protection. A clinical CHL preparation, evaluated in a human population subsequent to the seminal demonstration of CHL chemopreventive properties against AFB��� in trout (1), revealed CHL to be just as effective in reducing biomarkers of alfatoxin exposure to humans (2). Dietary administration of this clinical preparation along with DBP in the rainbow trout demonstrated CHL protective capacity against DBP-initiated multi-organ DNA adduct formation and final tumor incidence. Sucrose was evaluated, deemed unlikely to be sequestered in a complex with CHL, and was used as a control in a pharmacokinetic study evaluating the biodistribution of DBP with and without CHL. The results provide evidence against a non-specific masking mechanism for CHL-mediated blocking of DBP (or aflatoxin)-initiated tumorigenesis. CHL at multiple doses provided significant protection against multi-dose DBP-initiated DNA adduction and tumor formation in multiple organs. CHL-mediated protection, primarily by reduced carcinogen biouptake and consistent with a complexation mechanism, is supported by these results. / Graduation date: 2003

During the past 30 years, numerous studies have focused on the toxicities of polycyclic aromatic hydrocarbons (PAH). Laboratory and field studies have helped elucidate the detrimental effects of these chemicals on growth, reproduction and immune response. Polycyclic aromatic hydrocarbons are in the priority list of chemicals to be studied by different governmental agencies and universities and understanding their mechanisms of action is the focus of the current research. The manuscripts presented in this dissertation are focused on the effects and mechanism of action of PAH on disease susceptibility. After a dietary exposure to PAH for up to 50 days (chapter II) and samplings after 3, 7, 14, 28 and 50 days, a number of biomarkers of PAH exposure were measured: Fluorescent aromatic compounds (FACs) in bile, ethoxyresorufin-o-deethylase (EROD) in liver microsomes, cytochrome P450 1A immunohistochemistry in liver and kidney and adduct formation in liver. Additionally markers of oxidative stress were measured: comet assay in blood, protein nitration in kidney and F2-isoprostanes in kidney. Oxidative stress was a probable factor in PAH induced responses in fish adapted to long-term PAH exposures and aryl hydrocarbon activation was not necessarily involved in this process. Disease challenge with Aeromonas salmonicida (chapter III) resulted in differences in mortalities that demonstrated that fish exposed to PAH were more susceptible to disease than fish not exposed to PAH. Determination of gene expression in head kidney of fish exposed and not exposed to PAH challenged with A. salmonicida using microarray and RT-PCR technologies 2, 4, 10 and 20 days after challenge (chapter IV), suggested that PAH exposure was associated with down regulation of interleukin 8, transport associated protein 1, NF-kB modulator, recombination activating gene and major histocompatibility complex II two days after challenge in fish exposed to PAH. The transcript levels were closer to control levels 20 days after challenge, this indicated a recovery from the effect of PAH exposure. / Graduation date: 2006

Graduation date: 1994

The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing hormone (CRH) are involved in the hypothalamic-pituitary-interrenal (HPI) axis. During stress, the HPI axis is activated and cortisol is released into the blood. In addition to their role in the HPI axis, AVT and CRH also have behavioural effects. The roles of AVT and CRH in stress responses and agonistic behaviour were studied in this thesis, using two different models. In the first model, two strains of rainbow trout (Onchorhynchus mykiss) divergent in stress-induced release of cortisol were investigated. This was done by observing behaviour and stress responses under different conditions. These strains were found to have divergent stress coping strategies based on the observed behaviour and levels of plasma cortisol. This divergence in behaviour could be associated with the CRH system, since the mRNA levels of CRH differed between the strains during stress. However, no differences between strains were observed in AVT or its receptor expressions. In the second model, non-selected rainbow trout were paired and the effect of intracerebroventricular (icv) injections of an active substance (AVT, CRH or the CRH related peptide Urotensin-I (UI)) on fights for dominance was investigated. One fish of the pair received the active substance icv and the other received saline icv. Fish receiving AVT became subordinate in accordance with the suggestion that AVT attenuates aggression in territorial vertebrates. Fish receiving CRH became subordinate whereas UI showed no effect on fights for dominance. Further, both CRH and UI induced an anxiety-related behaviour similar to non-ambulatory motor activity in rats. In addition, CRH appeared to affect the dopaminergic and serotonergic systems. In this thesis, it is suggested that CRH is involved in the behavioural modulation of the stress coping strategies in teleost fish. Further, AVT and CRH seem to act inhibitory on aggressive behaviour.

Aquatic organisms in response to toxic insults from environmental pollutants activate defence systems including the aryl hydrocarbon receptor (AhR) in an attempt to metabolize and excrete these toxicants and their metabolites. These detoxification mechanisms however may come with certain energetic costs. I hypothesize that the activation of the AhR by β-Naphthoflavone (β-NF), a model AhR agonist, results in increased energetic costs requiring metabolic reorganization in rainbow trout hepatocytes. While the results obtained suggest that there are no significant energetic costs of AhR activation, analysis of enzyme activities suggests possible metabolic reorganization. This study also showed significant changes in cellular processes in hepatocytes over the incubation periods which previously were not reported. Furthermore, for the first time in fish hepatocytes, metabolic flux analysis (MFA) was used to examine intra-cellular metabolism, the applicability of which is discussed.