Thesis (M. Sc.), Memorial University of Newfoundland, 1998. / Restricted. Bibliography: leaves 91-96.

The allocation of energetic resources into competing physiological systems is crucial for the survival and fitness of an organism. Maintenance of active growth and effective immune function is energetically costly and therefore, trade-offs should have evolved to optimise the allocation of resources into these systems according to physiological status. While recent studies have begun to elucidate the mechanisms by which cross-talk exists between these two systems, more work is needed to characterise their interactions. A high-throughput proteomics approach was developed to investigate the molecular mechanisms underpinning fast growth and molecular cross-talk between growth and immune function. This approach revealed unique routes to fast growth in two different growth-accelerated coho salmon strains, including increased protein synthesis in fish overexpressing growth hormone (GH) through a focussed up-regulation of translation machinery. Conversely, selectively-bred fish showed more complex alterations in multiple metabolic pathways potentially underlying increased growth and domestication. Additionally, the liver proteome response of rainbow trout to a bacterial challenge unveiled host defence and immune proteins upregulated during the acute phase response (APR), along with candidate proteins involved in re-allocation of energetic resources during an immune response. Additionally, novel genetic expansions of salmonid complement C3 proteins upregulated during bacterial challenge were identified and characterised. Finally, the AMP-activated kinase (AMPK) system was investigated due to its role in managing energetic status, making it an ideal system to investigate crosstalk between growth and immunity. Novel salmonid-specific genetic expansions in AMPK subunits (α, β and γ) were demonstrated and their mRNA level expression analysed in fast-growing fish strains exposed to immune stimuli, where an increase in expression of several subunits was observed for fish overexpressing GH. However, a significant downregulation in expression of several AMPK subunit genes occurred in response to immune stimuli. Overall, this project provides insights into links between growth and immune function in salmonids, which are relevant to the aquaculture industry, where the aim is to maximise fish growth while retaining strong immunocompetence.

Graduation date: 1995

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003. / Appendix reprints five papers and manuscripts co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

In order to provide an accurate basis for the correlation of endocrine changes and phases of the reproductive (and associated) cycles in the powan of Loch Lomond, 'Coregonus- lavaretus (L.), the following experiments were carried out, Cell types in the pituitary were identified using light microscopy and transmission electron microscopy. To locate gonadotropic cells an immunofluorescence technique was employed using antibody prepared in rabbit and an immunodiffusion method to detect the presence of antibody in the rabbit serum. In order to purify pituitary gonadotropin, two purification techniques 'were used. One was alcoholic extraction followed by gel filtration on sephadex; the other was buffer extraction followed by affinity chromatography on Concanavalin A-sepharose. To characterise the fractions from columns, two in vitro bioassays were employed; (i) ovulation of the oocytes of medaka (Oryzias latipes); (ii) Cyclic AMP production in immature trout gonads. The concentration of pituitary gonadotropins was measured using a heterologous radioimmunoassay technique. Using a radioimmunoassay technique, the serum testosterone and oestradiol-17β concentrations were determined. Serum proteins were characterised using SDS gel electrophoresis.

The pathogen Piscirickettsia salmonis, has been isolated from all species of salmonid and has been found in Chile, Canada, Ireland, Norway and Scotland. Rickettsia-like organisms from European sea bass (Dicentrarchus labrax) were found to share common antigens with the P. salmonis type-strain, LF-89 using the indirect fluorescent antibody test (IFAT) and immunohistochemistry (IHC). In addition, the DNA sequences of the 16S rDNA and 16S-23S internal transcribed spacer region (ITS) were compared with those published for P. salmonis strains and showed that the sea bass piscirickettsia-like organism (SBPLO) was another strain of P. salmonis, closely related to the salmonid pathogens. The ability of P. salmonis to survive and replicate within head kidney (HK) macrophages of rainbow trout infected in vitro was demonstrated using transmission electron microscopy (TEM) at various times post-infection (p.i.). However, macrophages derived from fish vaccinated against P. salmonis appeared to clear in vitro infection more rapidly than macrophages from naive fish. Polymerisation of filamentous actin within the cytoplasm of the host cell is used by some mammalian rickettsiae to achieve intercellular spread by actin-based motility (ABM). Both TEM and confocal microscopy were used to investigate possible actin tail formation by P. salmonis. No evidence of tail formation was found. Respiratory burst (RB) by P. salmonis was measured following exposure of rainbow trout HK macrophages to the organisms in vitro. Because of background stimulation of the RB by growth media and debris from the CHSE-214 cells used to culture P. salmonis, it was not possible to detect any effect of the pathogen on the burst. Schering Plough Aquaculture has developed a recombinant vaccine against P. salmonis. The ability of the vaccine to elicit a memory response against P. salmonis was investigated by measuring three different immune responses: a) the expression of iNOS was measured by reverse transcription polymerase chain reaction (RT-PCR) to detect mRNA levels or by the Greiss reaction to quantify the end-products of nitric oxide metabolism in the serum. Increased iNOS expression was not detected in rainbow trout kidney or serum following vaccination/challenge with P. salmonis. However, iNOS expression was detected in gill tissue from naive trout which suggests that expression may be constitutive in this tissue. b) the production of macrophage activating factor (MAF) by lymphocytes from vaccinated trout, following stimulation in vitro with P. salmonis, was measured by the ability of supernatants from these cells to prime elevated RB in naive macrophages. No difference in priming ability between supernatants from vaccinated and non-vaccinated fish was detected. However, macrophages among the immune leukocytes used to produce the MAF supernatants did exhibit elevated RB compared with macrophages from non-immune fish, suggesting that vaccination had produced a population of lymphocytes capable of priming activation of macrophages. c) by screening individual sera concurrently against the rickettsial and CHSE antigen preparations, the antibody response to P. salmonis could be detected specifically and was found to increase significantly in immunised fish by 6 weeks post-vaccination. Specificity of the response was demonstrated by screening the sera against Aeromonas salmonicida.

The importance of hormone reservoirs in mature teleost eggs is unknown. To elucidate the effects of hormones on embryonic development, steelhead trout eggs, Oncorhynchus mykiss, were immersed in either cortisol, testosterone, or thyroxine at two different stages of development. Elevated concentrations of cortisol were detectable in the trout eggs or embryos after immersion. Eggs exposed to cortisol during water hardening hatched faster than eggs exposed at the eyed stage. Eggs that hatched faster had elevated cortisol and cortisol glucuronide concentrations at hatch compared to groups immersed at eyed or control groups. The dedine of these elevated concentrations of cortisol and cortisol glucuronide during embryonic development suggest conversion, clearance or both. Eggs exposed to cortisol at the earlier developmental stage did not appear to clear or convert cortisol as efficiently as those exposed at a later stage. Testosterone did not accelerate hatching in steelhead trout. Thyroxine accelerated hatching in eggs immersed at the eyed stages but had no effect when given at water hardening. These eggs that hatched faster were more synchronous in hatching time compared to other groups. Prior to exogenous feeding (50 days post fertilization, dpf), animals immersed in cortisol when eye pigments had higher mean condition factor (Kn) than other experimental or control groups, but this effect was gone by 83 dpf. However, at 130 dpf, cortisol groups that were immersed at the eyed stage were again heavier, longer, and more robust than other groups. At 50 dpf, animals immersed in thyroxine at water hardening were significantly longer and less robust (smaller condition factor, Kn). These effects disappeared by 83 dpf. / Graduation date: 1993

Graduation date: 1993

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 90-91). Also available via Humboldt Digital Scholar.

Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (leaves 49-56).