No description available.

Chemokines are chemotactic cytokines that have the ability to attract leukocytes and guide them via a concentration gradient to sites of injury/infection. These small, basic proteins are secreted when induced and act on their target cells through G-protein coupled receptors. The downstream effects of this family of immune molecules are vast and have not fully been characterized. These versatile molecules seem to be able to serve as a link between the innate and adaptive immune systems as they are capable of inducing the inflammatory response of the innate immune system as well as triggering the initiation of the adaptive immune system. There are currently 46 known chemokines in humans. Chemokines have also been isolated from mouse, chicken, frog and fish. The rainbow trout chemokine CK-2 is the only known functional CC chemokine in possession of a mucin stalk. A previous study in this lab showed that stimulation by PHA causes a decrease in CK-2 transcript levels in rainbow trout head kidney and peripheral blood leukocytes (PBLs) as well as in the rainbow trout macrophage-like cell line RTS-11. CK-2 protein was found expressed in RTS-11 but not in the spleen tissues of stimulated fish. A chemotaxis assay was performed to determine the activity of recombinant CK-2. It was observed that recombinant CK-2 induces the migration of rainbow trout PBLs as well as RTS-11 cells at an optimal concentration of 100ng/mL when purified under native conditions. The migration of cells treated with pertussis toxin is significantly reduced, indicating that it relies on G-protein coupled receptors. Treatment of RTS-11 cells with recombinant CK-2 results in changes in the expression profiles of various immune response genes including those that are involved in the inflammatory response and the responses against both intracellular and extracellular pathogens. Interestingly, rCK-2 induced an upregulation in the expression of the surface molecule CD4 at the level of transcription. The increase in CD4 may suggest a possible role for CD4 in the regulation of the cell’s response to chemokines, indicating a potential function for the molecule in macrophages which has yet to be determined. This study shows that CK-2 is a functional chemokine that has a role in the rainbow trout immune response involving, but not limited to, macrophages.

Walleye are an important recreational and commercial fish species that are distributed over an expansive geographic range across North America. However, its palatable white flesh and appeal to anglers have lead to declines in natural populations throughout Canada and the United States. These declines have prompted the idea that aquaculture may serve as a means of satisfying consumer demands and decreasing pressure on wild stocks. While culture programs exist for walleye, little is known about the growth physiology of walleye in a culture system. The goals of this thesis, therefore, were to develop a molecular marker that could be used to rapidly assess growth in juvenile walleye, and to make improvements to culture practices that will optimize growth. To begin, we examined the relationship between growth and the expression of the myosin heavy chain gene (MyHC) in the white muscle of juvenile walleye. The coding region of MyHC from the fast skeletal muscle of walleye was amplified using a full length cDNA. Growth was then characterized using traditional measurements of growth (length, weight and condition factor), as well as MyHC protein concentration and MyHC mRNA levels. Both MyHC mRNA and protein expression were highly correlated with faster growth in juvenile walleye. Over shorter time scales, the MyHC mRNA marker was sensitive enough to detect impacts of fasting that could not be detected using traditional measurements of growth. Next, MyHC mRNA quantification was applied to an aquaculture setting. Feed training is an important bottleneck during juvenile walleye culture that often leads to mortalities and cannibalism. These experiments showed that the brief fasting period during the diet switch from plankton to commercial pellet feed caused a significant decrease in MyHC mRNA levels. Furthermore, the success of feed training in terms of survivorship and growth potential increased significantly for larger fish. The final section of this thesis examined how acute and chronic temperature exposure impacted MyHC mRNA and protein expression. Results showed that the nature of the heat stress can significantly affect the MyHC response. These findings are important as the temperature stresses induced in these studies are common during the summer months in southern Ontario. / Thesis (Ph.D, Biology) -- Queen's University, 2009-02-19 12:30:51.406

No description available.

Winter flounder, Pleuronectes americanus, is being developed for aquaculture in Atlantic Canada. Since larval culture has been successful, research can now address problems at the juvenile stage such as weaning, diet and optimal growth environment. Weaning, a critical stage in culture of any flatfish species, is the switch from live food to an artificial diet. In a three month study, I was able to wean wild young-of-the year winter flounder from live, cultured Artemia onto dry food. Specific growth rates and food conversion indicated the artificial diet was a better food source than Artemia. In a second study, I was able to wean recently-metamorphosed winter flounder reared in the laboratory, onto two artificial diets which differed in price and lipid content. There was no difference between the inexpensive salmonid starter diet and the more costly Nippai diet on growth and survival. In a third study, I examined the effects of temperature and density on wild year 0 and 1 winter flounder reared on dry salmonid diet. There was no effect of density on growth and survival over the ranges tested. Greatest growth occurred at 15$ sp circ$C, although survival was highest at ambient temperature.

No description available.

Although deflectors are commonly used in fish habitat rehabilitation projects to create and/or maintain pools, there is a lack of understanding of the complex flow field and scour patterns around these structures. The objective of this research is to quantify the 3D flow dynamics and the bed morphology around various designs of flow deflectors in a laboratory flume over a plain and mobile bed. 3D velocity measurements were taken with an acoustic Doppler velocimeter. After comparing different methods of bed shear stress estimates, it was determined that the turbulent kinetic energy approach was best at capturing the shear stress amplification near the deflectors. Deflectors oriented perpendicular to the flow create the most important disturbance of the flow field, the greatest increase in turbulence intensity and the largest scour hole, followed by upstreamoriented deflectors (135°) and downstream-oriented ones (45°). 90° deflectors would therefore potentially provide the greatest benefit for fish habitat rehabilitation.

The impact of the source of n-3 fatty acids on cardiovascular disease has not been fully investigated. This study was carried out to investigate cardiovascular benefits of diets with a low ratio (2:1) of n-6:n-3 fatty acids from different sources, either fish or flaxseed oil, in C57BL/6 mice. Twenty-one mice were divided into 3 groups (n=7) and fed an atherogenic diet supplemented with either a fish or flaxseed oil-based ‘designer oil’ with low n-6:n-3 fatty acid ratio (treated groups) or safflower oil-based formulation with a high ratio (control group) for 16 weeks. Plasma cholesterol levels declined significantly in both treated groups, by greater than 30%, compared to those in control. The ratio of n-6:n-3 fatty acids in liver was significantly lower in fish and flax groups as compared to control. Our data suggest that lowering dietary ratio of n-6:n-3 fatty acids may significantly reduce cardiovascular risks regardless of the source of n-3 fatty acids.

Oil and gas exploration in Northern Canada uses explosive-based seismic techniques to locate hydrocarbon reserves beneath waterbodies not frozen to the bottom. The use of explosives in, or near, waterbodies has the potential to harm fishes, primarily through instantaneous pressure changes (IPCs) generated from the detonations. These IPCs can damage soft tissues through the rapid compression and expansion of the swimbladder as the pressure wave passes. In Canada, a document entitled Guidelines for the Use of Explosives In or Near Canadian Fisheries Waters recommends that peak pressures not exceed 100 kPa for the protection of fish, however damage has been reported below this level. To simulate seismic exploration and examine potential pathological changes surrounding the current Guideline, fish across different developmental stages and with varying degrees of swimbladder presence were exposed to a variety of explosive based IPC levels in field experiments. Early life stages of rainbow trout (Oncorhynchus mykiss) including eyed eggs, sac fry, and juveniles were caged and exposed to discrete detonations from 0 to 280 kPa in the Mackenzie Delta, NWT. These fish were subsequently examined for both gross pathological and histological changes to cranial structures as well as swimbladder, kidney, liver and gill tissue. Results showed changes in both the area and circumference of the cranial region of eyed eggs, as well as swimbladder, ocular and kidney damage in juveniles. Additionally, caged adult swimbladder bearing lake trout (Salvelinus namaycush) and non-swimbladder bearing slimy sculpin (Cottus cognatus) were exposed to explosive based IPCs ranging in peak pressure from 0 to 127 kPa at the Experimental Lakes Area, Ontario. Fish were later examined grossly and blood, liver, kidney, intestine, and spleen were examined to determine the presence of any traumatic based pathological changes. Results indicated the occurrence of swimbladder hemorrhage in lake trout exposed to IPCs near the current Guideline level. Finally, a risk assessment for lake trout of the Mackenzie Delta exposed to IPCs was undertaken; to examine the potential for adverse risk to individuals and populations, and the likelihood of populations being unable to recover. Based on the findings of the aforementioned studies, the recommended Guideline level is not protective of early life stages of rainbow trout and furthermore represents the threshold at which damage to the swimbladder in adult lake trout does not occur, as such, a re-examination of the recommended Guideline level is warranted.

This thesis presents the findings of a physical modeling study examining the hydraulic characteristics within the inlet region of a corrugated steel pipe (CSP) culvert with common inlet treatments. Also examined are the effects of embedding the culvert below the stream bed and backfilling the culvert with granular material. Velocity and turbulence distributions were examined in an effort to better understand how these inlet treatments may affect fish passage. The velocity field of each inlet configuration was dominated by a central jet of high velocity surrounded by low velocity boundary areas. Based on percent area analysis the various projecting end inlet configura-tions presented the largest area with streamwise velocities less than Uavg. The usefulness of the low velocity boundary areas may be limited by significant vertical and spanwise velocities and associated elevated turbulence levels.