Feeding experiments were conducted on Atlantic pollock (Pollachius virens) to examine the variability in tissue fatty acid (FA) composition and stable carbon isotope fractionation of FA during digestion, assimilation and mobilization of lipids. The FA profiles and compound-specific carbon isotopes of chylomicrons, liver, muscle and fasted serum were compared to diet. FA analysis demonstrated similarity among tissue groups despite differences in feeding states. The FA results indicate the blood of post-prandial fish may serve as an alternative to tissue biopsies for the estimation of marine fish diets with compound-specific isotope analysis (CSIA). Despite similarity among FA profiles, the carbon isotope discrimination factors of FA varied independently, which suggests that fractionation is influenced by the degree to which individual FA are oxidized. These results provide preliminary information that is necessary in order to use CSIA to estimate the effects of fish diets.

The biological activity of α-linolenic acid (ALA) is poorly understood and primarily associated with its conversion to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This study used the Δ6 desaturase knockout (D6KO) mouse, which lacks Δ6 desaturase and therefore cannot convert ALA, to evaluate the independent effects of ALA on preventing non-alcoholic fatty liver disease (NAFLD). First, the capacity of very long chain fatty acids to rescue the D6KO lipid profile was established. Next, to evaluate the independent effects of ALA, D6KO or wild-type mice were fed diets containing lard, canola, flaxseed, or fish oil. Following treatment, liver phospholipid fatty acid composition was evaluated and livers were scored for steatosis and inflammation. Glucose tolerance was also evaluated. D6KO mice fed ALA-rich diets had lower liver lipid accumulation, lower hepatic inflammation (8 weeks) and improved glucose tolerance (20 weeks) relative to lard-fed D6KO mice. Overall, this thesis supports an independent biological role for ALA. / D.W.L. Ma is funded by the Canola Council of Canada, Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation Leaders Opportunity Fund with matching from the Ontario Research Fund; Jessica Monteiro is funded Ontario Graduate Scholarship.

Brassica napus is known to contain an endogenous and soluble stearoyl-acyl carrier protein (^918:0-ACP) desaturase, but does not express a palmitic (16:0)-ACP desaturase. Levels of 16:0 are low in canola oil and are associated with enhanced cholesterol biosynthesis in humans. In an attempt to further reduce the saturated fatty acid (SFA) content of canola oil, B. Napus L. cv Westar was transformed with a cDNA encoding a ^916:0-ACP desaturase from cat's claw (Doxantha unguis-cati L.). Arabidopsis thaliana was also transformed with this cDNA. Transformation of both oilseeds resulted in increased production of palmitoleic acid (^16:1) and many other effects of fatty acid composition. Overall, the SFA content did not decrease in either oilseed and investigation to why this effect occurred was examined using transgenic B. napus. Molecular genetic testing on second generation B. napus also determined the plants contained the cDNA of interest and were transcribing the cDNA. / xxi, 155 leaves : ill. ; 29 cm.

The effect of fatty acids on energy metabolism has been shown to be dependent on their acyl structure. In humans, following short term feeding, medium chain triglycerides (MCT) have been shown to increase the thermic effect of food and fat oxidation as compared to long chain triglycerides (LCT). Short term results in animals have been comparable. In longer term, animal studies, MCT vs. LCT have resulted in less weight gain during overfeeding or refeeding after weight loss. However, observations of the longer term effects of MCT in humans beyond 7 days are sparse and inconclusive. Hence, the objective of the thesis was to examine the effects of MCT vs. LCT on total energy expenditure, its components basal metabolic rate and thermic effect of food, and on substrate oxidation, including both exogenous and endogenous fat oxidation for a period of one week, following one week of prefeeding. Twelve healthy college aged women were fed eucaloric 14 days diets enriched with either MCT or LCT in a randomized cross over design, with a two week washout period. Doubly labelled water, respiratory gas exchange analysis, and 1-13C labelled myristic, palmitic, and stearic acids were used to measure total energy expenditure, components of energy expenditure, and endogenous long chain fatty acid oxidation, respectively. The presence of MCT in the diet significantly increased endogenous oxidation of labelled long chain fatty acids following 14 days of feeding, while the presence of LCT did not. Respiratory gas exchange analysis showed significantly increased basal metabolic rate on day 7 of MCT vs. LCT feeding, but this effect of diet was reduced to a trend by day 14. Dietary treatment did not result in significant differences in total energy expenditure during the second week of feeding. These results suggest that, after two weeks of feeding, MCT continue to affect energy metabolism through increased endogenous fat oxidation and a suggestion of heightened basal metabolic rate, but

ABCD2 (D2) is a peroxisomal ATP binding cassette (ABC) transporter that is expressed in brain, adrenal and liver. D2 is transcriptionally regulated by key transcriptional factors that control lipid and glucose metabolism. Therefore, we examined its role in adipose tissue. These studies revealed that D2 is highly abundant in adipose tissue and upregulated during adipogenesis. However, D2 deficiency does not affect either adipogenesis or lipid accumulation. An examination of the lipid profile of adipose tissue revealed the accumulation of C20 and C22 fatty acids in D2 deficient (D2‐/‐) mice. When challenged with a diet enriched in erucic acid (C22:1, 10% kcal), this lipid accumulated in both liver and adipose tissue. Following 8 weeks of diet, D2‐/‐ mice showed increased adiposity, glucose intolerance, dyslipidemia and steatosis. Analysis of the hepatic lipid profile showed significant changes away from poly unsaturated fatty acids (PUFAs) and toward C18‐22 mono‐unsaturated fatty acids (MUFA). RT‐PCR of the mRNA from the adipose tissue and liver revealed significant changes in lipogenic (ACC, SCD1 & 2) and PUFA synthesis (Δ5 & 6‐desaturase) genes in D2‐/‐ mice. The molecular mechanisms by which D2 regulates lipid metabolism in adipose tissue remains unclear. To explore potential mechanisms, the subcellular localization of D2 in adipose tissue was determined. Our results demonstrated that D2 resides in a distinct subclass of peroxisomes that does not containing classical peroxisomal markers such as pex19 or PMP70, but are positive for pex14. In conclusion, our studies reveal a novel role of D2 and peroxisomes in the protection from disruptions of lipid metabolism induced by dietary erucic acid and that D2 resides in a unique compartment within adipocytes that plays a yet to be elucidated role in the regulation of lipid metabolism.

Includes bibliographical references (leaves 237-257). / xx, 257 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates the mechanisms underlying the antiarrhythmic effects of omega-3 polyunsaturated fatty acids using adult rat ventricular cardiac myocytes. / Thesis (Ph.D.)--Adelaide University, Dept. of Physiology, 2001

Thesis (Ph.D.). / Written for the School of Dietetics and Human Nutrition. Title from title page of PDF (viewed 2008/07/23). Includes bibliographical references.

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 131-132). Also available on the Internet.

Thesis (Ph. D.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains x, 125 p. : ill. Vita. Includes abstract. Includes bibliographical references.