Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Feb. 8, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Animal Science, Department of Agricultural, Food and Nutritional Science, University of Alberta. Includes bibliographical references.

Lam, Cheuk Kai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 148-173). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.i / ABSTRACT --- p.ii / LIST OF ABBREVIATIONS --- p.vi / TABLE OF CONTENTS --- p.x / Chapter CHAPTER 1 --- GENERAL INTRODUCTION / Chapter 1.1 --- Introduction to Cholesterol and Its Related Diseases --- p.1 / Chapter 1.1.1 --- Chemistry of cholesterol --- p.1 / Chapter 1.1.2 --- Physiological importance of cholesterol --- p.1 / Chapter 1.1.3 --- Pathological effects of cholesterol --- p.3 / Chapter 1.1.3.1 --- Mechanism of atherosclerosis --- p.3 / Chapter 1.2 --- Cholesterol Homeostasis --- p.6 / Chapter 1.2.1 --- Liver as the main organ for cholesterol metabolism --- p.6 / Chapter 1.2.2 --- Regulatory sites of cholesterol metabolism --- p.6 / Chapter 1.2.2.1 --- Regulation of cholesterol absorption by acyl coenzyme A: cholesterol acyltransferase (ACAT) --- p.6 / Chapter 1.2.2.2 --- Sterol regulatory element-binding protein 2 (SREBP-2) as a transcription factor for 3 -hydroxy-3 -methylglutaryl coenzyme A reductase (HMGR) and low-density lipoprotein receptor (LDLR) --- p.10 / Chapter 1.2.2.3 --- Roles ofLDLR --- p.11 / Chapter 1.2.2.4 --- Rate limiting role of HMGR in cholesterol de novo synthesis --- p.14 / Chapter 1.2.2.5 --- Roles of liver-X-receptor-a (LXR-a) in cholesterol catabolism --- p.16 / Chapter 1.2.2.6 --- Roles of CYP7A1 in catabolism of cholesterol into bile acids --- p.19 / Chapter 1.2.2.7 --- Roles of cholesterol ester transfer protein (CETP) in maintaining cholesterol distribution in blood --- p.22 / Chapter CHAPTER 2 --- EFFECT OF OCTADECAENOIC ACIDS ON BLOOD CHOLESTEROL IN HAMSTERS / Chapter 2.1 --- Introduction --- p.25 / Chapter 2.1.1 --- Effects of polyunsaturated fatty acids (PUFAs) on blood cholesterol --- p.25 / Chapter 2.1.2 --- Differential effects of 18-C PUFAs on lowering blood cholesterol in vivo --- p.25 / Chapter 2.1.3 --- "Structures, metabolism and conjugation of octadecaenoic acids (ODA)" --- p.26 / Chapter 2.1.4 --- Objectives --- p.26 / Chapter 2.2 --- Experiment 1 --- p.28 / Chapter 2.2.1 --- Materials and methods --- p.28 / Chapter 2.2.1.1 --- Experimental fatty acids --- p.28 / Chapter 2.2.1.1.1 --- Isolation of LN from flaxseed --- p.28 / Chapter 2.2.1.1.2 --- Isolation of CLN from tung seed --- p.28 / Chapter 2.2.1.2 --- Animals --- p.29 / Chapter 2.2.1.3 --- Diets --- p.30 / Chapter 2.2.1.4 --- Plasma lipid measurements --- p.30 / Chapter 2.2.1.5 --- Plasma CETP activity measurement --- p.30 / Chapter 2.2.1.6 --- "Measurement of liver SREBP-2, LDLR, HMGR and CYP7A1 protein abundance by Western blotting" --- p.34 / Chapter 2.2.1.7 --- "Measurement of hepatic SREBP-2, LDLR, HMGR, LXR, CYP7A1, CETP, SR-B1 and LCAT mRNA by real time PCR" --- p.35 / Chapter 2.2.1.7.1 --- Extraction of mRNA --- p.35 / Chapter 2.2.1.1.2 --- Complementary DNA synthesis --- p.36 / Chapter 2.2.1.7.3 --- Real-time polymerase chain reaction (PCR) anaylsis --- p.36 / Chapter 2.2.1.8 --- Determination of cholesterol in liver --- p.37 / Chapter 2.2.1.9 --- Determination of fecal neutral and acidic sterols --- p.38 / Chapter 2.2.1.9.1 --- Determination of fecal neutral sterols --- p.39 / Chapter 2.2.1.9.2 --- Determination of fecal acidic sterols --- p.41 / Chapter 2.2.1.10 --- Statistics --- p.43 / Chapter 2.2.2 --- Results --- p.44 / Chapter 2.2.2.1 --- Growth and food intake --- p.44 / Chapter 2.2.2.2 --- Organ weights --- p.44 / Chapter 2.2.2.3 --- "Effects of ODA on serum TC, TG and HDL-C" --- p.44 / Chapter 2.2.2.4 --- Effect of ODA on liver cholesterol --- p.48 / Chapter 2.2.2.5 --- Effect of ODA on fecal neutral sterol output --- p.48 / Chapter 2.2.2.6 --- Effect of ODA on fecal acidic sterol output --- p.48 / Chapter 2.2.2.7 --- Effect of ODA on cholesterol balance in hamsters --- p.52 / Chapter 2.2.2.8 --- Effect of ODA on plasma CETP activity --- p.52 / Chapter 2.2.2.9 --- Correlation between blood TC and liver cholesterol --- p.52 / Chapter 2.2.2.10 --- Correlation between blood HDL-C and liver cholesterol --- p.52 / Chapter 2.2.2.11 --- Correlation between blood nHDL/HDL ratio and liver cholesterol --- p.52 / Chapter 2.2.2.12 --- Effect ofODA on liver SREBP-2 immunoreactive mass --- p.58 / Chapter 2.2.2.13 --- Effect of ODA on liver LDLR immunoreactive mass --- p.58 / Chapter 2.2.2.14 --- Effect of ODA on liver HMGR immunoreactive mass --- p.58 / Chapter 2.2.2.15 --- Effect of ODA on liver LXR immunoreactive mass --- p.58 / Chapter 2.2.2.16 --- Effect of ODA on liver CYP7A1 immunoreactive mass --- p.63 / Chapter 2.2.2.17 --- Effects ofODA on hepatic CETP mRNA --- p.65 / Chapter 2.2.2.18 --- Effects of ODA on hepatic LDLR mRNA --- p.65 / Chapter 2.2.2.19 --- Effects of ODA on hepatic LXR mRNA --- p.65 / Chapter 2.2.2.20 --- Effects of ODA on hepatic CYP7A1 mRNA --- p.65 / Chapter 2.3 --- Experiment 2 --- p.70 / Chapter 2.3.1 --- Materials and Methods --- p.70 / Chapter 2.3.1.1 --- Experimental diets --- p.70 / Chapter 2.3.1.2 --- Animals --- p.70 / Chapter 2.3.1.3 --- Intestinal acyl coenzyme A: cholesterol acyltransferase (ACAT) activity measurement --- p.70 / Chapter 2.3.1.3.1 --- Preparation of intestinal microsome --- p.71 / Chapter 2.3.1.3.2 --- ACAT activity assay --- p.71 / Chapter 2.3.2 --- Results --- p.73 / Chapter 2.3.2.1 --- Growth and food intake --- p.73 / Chapter 2.3.2.2 --- Organ weights --- p.73 / Chapter 2.3.2.3 --- "Effect of ODA on serum TC, TG and HDL-C" --- p.73 / Chapter 2.3.2.4 --- Effect of ODA feeding on fecal neutral sterol content --- p.77 / Chapter 2.3.2.5 --- Effect of ODA feeding on fecal acidic sterol content --- p.77 / Chapter 2.3.2.6 --- Effect of ODA feeding on intestinal acyl coenzyme A: acyl cholesterol transferase (ACAT) activity --- p.77 / Chapter 2.4 --- Discussion --- p.81 / Chapter CHAPTER 3 --- EFFECT OF OCTADECAENOIC ACIDS ON CHOLESTEROL-REGULATING GENES IN HepG2 / Chapter 3.1 --- Introduction --- p.86 / Chapter 3.1.1 --- HepG2 as a model of cholesterol regulation --- p.86 / Chapter 3.1.2 --- Effect of polyunsaturated fatty acids (PUFAs) on cholesterol regulating genes in cultured cells --- p.87 / Chapter 3.1.3 --- Objectives --- p.89 / Chapter 3.2 --- Materials and Methods --- p.90 / Chapter 3.2.1 --- Cell culture --- p.90 / Chapter 3.2.2 --- "Measurement of SREBP-2, LDLR, HMGR and CYP7A1 protein abundance by Western blotting" --- p.92 / Chapter 3.2.3 --- "Measurement of cellular SREBP-2, LDLR, HMGR, LXR, CYP7A1 and CETP mRNA by real time PCR" --- p.93 / Chapter 3.2.4 --- Statistics --- p.93 / Chapter 3.3 --- Results --- p.95 / Chapter 3.3.1 --- Effect of ODA on HepG2 SREBP-2 immunoreactive mass --- p.95 / Chapter 3.3.2 --- Effect of ODA on HepG2 HMGR immunoreactive mass --- p.95 / Chapter 3.3.3 --- Effect of ODA on HepG2 LDLR immunoreactive mass --- p.95 / Chapter 3.3.4 --- Effect of ODA on HepG2 LXR immunoreactive mass --- p.95 / Chapter 3.3.5 --- Effect of ODA on HepG2 CYP7A1 immunoreactive mass --- p.96 / Chapter 3.3.6 --- Effect of ODA supplementation on HepG2 SREBP-2 mRNA expression --- p.102 / Chapter 3.3.7 --- Effect of ODA supplementation on HepG2 SREBP-2 mRNA expression --- p.102 / Chapter 3.3.8 --- Effect of ODA supplementation on HepG2 LDLR mRNA expression --- p.102 / Chapter 3.3.9 --- Effect of ODA supplementation on HepG2 LXR mRNA expression --- p.106 / Chapter 3.3.10 --- Effect of ODA supplementation on HepG2 CYP7A1 mRNA expression --- p.106 / Chapter 3.3.11 --- Effect of ODA supplementation on HepG2 CETP mRNA expression --- p.106 / Chapter 3.4 --- Discussion --- p.110 / Chapter CHAPTER 4 --- EFFECT OF APPLE POLYPHENOLS ON BLOOD CHOLESTEROL IN HAMSTERS / Chapter 4.1 --- Introduction --- p.114 / Chapter 4.1.1 --- Apple is a commonly consumed fruit worldwide --- p.114 / Chapter 4.1.2 --- Potential health effects of apples --- p.114 / Chapter 4.1.3 --- Abundance of polyphenols in apple --- p.115 / Chapter 4.1.4 --- Fuji variety of apple --- p.116 / Chapter 4.1.5 --- Objectives --- p.116 / Chapter 4.2 --- Materials and Methods --- p.118 / Chapter 4.2.1 --- Isolation of AP --- p.118 / Chapter 4.2.2 --- Characterization of AP extract --- p.118 / Chapter 4.2.3 --- Effect of AP on CETP activity in vitro --- p.118 / Chapter 4.2.4 --- Effect of AP on blood cholesterol in hamsters --- p.119 / Chapter 4.2.4.1 --- Animals --- p.119 / Chapter 4.2.4.2 --- Diets --- p.120 / Chapter 4.2.4.3 --- Plasma lipids measurement --- p.121 / Chapter 4.2.4.4 --- Plasma CETP activity measurement and immunoreactive mass by Western blotting --- p.123 / Chapter 4.2.4.5 --- "Measurement of liver SREBP-2, LDL-R, HMG-R and CYP7A1 protein abundance by Western blotting" --- p.124 / Chapter 4.2.4.6 --- Statistics --- p.124 / Chapter 4.3 --- Results --- p.125 / Chapter 4.3.1 --- Polyphenol content in AP --- p.125 / Chapter 4.3.2 --- Effect of AP on CETP activity in vitro --- p.125 / Chapter 4.3.3 --- Growth and food intake --- p.128 / Chapter 4.3.4 --- Organ weights --- p.128 / Chapter 4.3.5 --- Effect of AP supplementation on the plasma lipid profile of hamsters --- p.131 / Chapter 4.3.6 --- Effect of AP feeding on plasma CETP activity of the hamsters --- p.131 / Chapter 4.3.7 --- Effect of AP on plasma CETP immunoreactive mass --- p.134 / Chapter 4.3.8 --- Effect of AP on liver SREBP-2 immunoreactive mass --- p.134 / Chapter 4.3.9 --- Effect of AP on liver LDLR immunoreactive mass --- p.134 / Chapter 4.3.10 --- Effect of AP on liver HMGR immunoreactive mass --- p.134 / Chapter 4.3.11 --- Effect of AP on liver CYP7A1 immunoreactive mass --- p.134 / Chapter 4.3.12 --- Effect of AP on liver cholesterol level --- p.140 / Chapter 4.4 --- Discussion --- p.142 / Chapter CHAPTER 5 --- CONCLUSION --- p.145 / REFERENCES --- p.148

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Conjugated linoleic acid (CLA) is predominantly found in foods of ruminant origin such as milk and processed cheese, and has gained much interest recently due to its beneficial health and biological effects on animals and humans. / The bioconversion of linoleic acid (LA) and linolenic acid (LNA) by a selected Bifidobacterium from healthy infant feces was studied. Bifidobacterium breve JKL03 had the ability to convert linolenic acid (0.2 mg/ml) to CLNA in fermentation of skim milk medium for 24 h up to a yield of 72.0% (up to 74.7% under aerobic conditions) and linoleic acid (0.2 mg/ml) into CLA by fermentation in skim milk medium for 24 h up to a yield of 23.9% (up to 28.0% under aerobic conditions). / B. breve JKL03 was also co-fermented with Lactobacillus acidophilus (NCFMRTM strain), a commonly added starter culture, to observe the resulting effects on growth during fermentation for yogurt production. Fermentation of LNA in skim milk with B. breve JKL03 and L. acidophilus (NCFM) maintained high CLNA production level. On the other hand, CLA production in the same media with both strains did not exhibit as high level as with the single B. breve. / These results are important for the advancement of knowledge on the production of CLA and CLNA in dairy products and for knowledge on the basic metabolic mechanisms for such conversion.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 87-109). Also available in print.

No description available.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.

L'huile de lin est considérée comme une des plus riches en acide linolénique (oméga- 3), avec certaines variétés de lin oléagineux produisant jusqu'à 65% d'acide a-linolénique. Cette huile utilisée depuis longtemps en industrie chimique pour la confection de peintures, vernis, agents tensioactifs, présente aussi des bénéfices pour la santé humaine avec un apport journalier d'environ 2 g.f 1 (diminution de la pression artérielle, prévention de thrombose...). Il parait donc raisonnable aujourd'hui d'augmenter la production de l'huile de lin riche en oméga-3 pour répondre à ces différents besoins. La sélection de cultivars producteurs d'huile de la qualité demandée devient impérative. Pour cela, des connaissances sur les mécanismes de synthèse et d'accumulation AG polyinsaturés (PUFA) dans les graines de lin sont à acquérir. Dans ce contexte, nous avons évalué le rôle des enzymes de type LPAAT dans l'accumulation des PUFA dans le but de sélectionner des isoformes compétitives dans leur accumulation au niveau des TAG. Les gènes Lpaat ont été isolés à partir des graines de lin âgées de 20 JAF, phase active de remplissage en huile. La fonctionnalité des protéines correspondantes a été testée par complémentation dans une souche JC201 d’E. coli déficiente en activité LPAAT. Une caractérisation de ces enzymes a été effectuée par des tests in vitro et in vivo. Les résultats ont montré la présence d'une isoforme, nommée LPAAT2A, dont l'activité LPAAT présente une spécificité et sélectivité élevées vis-à-vis des PUFA. Dans un 2ème temps, nous avons mesuré in vitro et in vivo le potentiel des enzymes LPAAT provenant de litchi et de lin vis-à-vis des AG de type cyclopropanique. Ces AG possèdent des propriétés physico-chimiques intéressantes pour l'industrie des lubrifiants et des cosmétiques et sont produits par une enzyme spécifique « la CFA synthase ». Nous avons généré des lignées d'Arabidopsis exprimant la CFA synthase d’E.coli puis co-exprimé le gène Lpaat de litchi. Une augmentation de la teneur en AGC (AG cycliques) dans les lignées transgéniques obtenues reflète la spécificité de la LPAAT de litchi vis-à-vis des AGC. Nous nous sommes aussi intéressés aux enzymes de types sPLA2a (phospholipase A2). L'isolement du gène correspondant a été effectué à partir des graines de lin pendant la phase active de remplissage en huile. La caractérisation de son activité a été effectuée par des tests in vitro et in vivo. Les résultats ont montré que l'expression du gène sP/a2a de lin dans les graines d' Arabidopsis provoque une augmentation du poids de la graine ainsi qu'une augmentation du contenu en acide linolénique dans les TAG. L'ensemble de ces résultats montre l'existence d'un système enzymatique endogène chez le lin efficace vis-à­vis des PUFA et qui semble stimuler le métabolisme lipidique une fois exprimé chez Arabidopsis. / Flaxseed oil contain high amount of oméga-3 and present different industrials applications and human health benefits. ln this work, we aimed to identify enzymes allowing the accumulation of high level of omega-3 in linseed plants. ln this context, we evaluated the role of Lysophophatidic acid acyltransferases (LPAAT) and Phospholipases A2 (PLA2) enzymes in the accumulation of omega-3 by in vitro and in vivo approaches. Results showed the presence of a LPAAT2A isoform into flax genome having a high specificity and selectivity toward omega-3. Expression of Lpaat2A and sPia2a gene in Arabidopsis seeds increase seed weight, oil production and omega-3 content (up to 10% and 11%) in transformant seeds respectively. These results showed the presence in linseed plant of an efficient enzymatic system toward omega-3 accumulation. Furthermore, we have evaluated in vitro and in vivo the potential of Litchi and flax LPAAT enzymes toward the production of cyclopropane fatty acids (CFA). These fatty acids are naturally produced by a specific enzyme «CFA synthase» with physico-chemical properties interesting to lubricant and cosmetics industries. ln this context, we have generated Arabidopsis lines expressing E. coli Cfa synthase with or not co-expression of litchi Lpaat gene. Result showed an increase of 25% in the content of CFA in transgenic line co-expressing Cfa synthase and litchi Lpaat comparing to the transgenic lines expressing the CFA synthase. This increase in the level of CFA in transgenic seeds reflects the specificity of Litchi LPAAT toward CFA.

L’apport de graines oléagineuses dans la ration de la vache laitière pendant 1 à 3 mois pourrait améliorer la qualité nutritionnelle du lait, mais également pénaliser dans certains cas les performances zootechniques. Peu de données sont disponibles sur les effets de ces stratégies alimentaires sur de plus longues périodes. L’objectif de cette thèse est de quantifier au cours de 2 lactations consécutives, les effets de supplémentations en lin ou en trois différentes formes de colza de rations à base d’herbe conservée en hiver et pâturée en été sur les performances zootechniques de la vache laitière et la composition fine en acides gras du lait. Les effets des suppléments étudiés persistent au sein de chaque période (hiver et été) et sont répétables d’un été à l’autre. Ils sont par ailleurs similaires à ceux observés lors d’études de durée plus courte (1 à 3 mois). Ces stratégies ne permettent pas d’améliorer les performances zootechniques et diminuent parfois le taux protéique du lait, notamment en hiver. Toutefois, elles réduisent les teneurs du lait en acides gras saturés au profit de l’acide oléique et, dans le cas du lin de l’acide α-linolénique. Ces modifications peuvent être considérées comme une amélioration de la qualité nutritionnelle du lait. Cependant, le lin extrudé et le tourteau de colza gras augmentent les acides gras trans et les suppléments diminuent souvent l’acide ruménique du lait au pâturage. La distribution des isomères des acides gras insaturés cis et trans du lait dépend du type de graine et du niveau d’amidon de la ration, mais pas de la forme d’apport du colza, qui influence toutefois l’amplitude des effets observés. Par ailleurs, l’analyse détaillée du profil en acides gras du lait a permis de mieux comprendre le métabolisme des acides linoléiques et linoléniques conjugués, en lien avec la lipogenèse mammaire. / Addition of oilseed supplements to dairy cow diets for 1 to 3 months may improve the milk nutritional quality, but detrimental effects on animal performance may also occur. However, data is scarce on long-term effects of these nutritional strategies. The objective of this thesis was to quantify the effects of extruded linseed and three forms of rapeseed-derived supplements on dairy cow performance and detailed milk fatty acid composition, during 2 consecutive lactations. Basal diet was conserved grass during winter and pasture during summer. Oilseed supplements effects persist within each period (winter and summer) and are repeatable between the 2 summer periods. Long-term effects observed over 2 consecutive lactations are similar to those observed during short-term (1 to 3 months) studies. These oilseed-derived supplements not improve dairy cow performance, but decrease the milk protein content in some instances, especially during winter period. Nevertheless, oilseed supplementations reduce milk saturated fatty acid content and increase milk content in oleic acid and with linseed in α-linolenic acid. Such changes could be considered as an improvement of the milk nutritional quality. However, extruded linseed and fat-rich rapeseed meal increase milk trans fatty acid content, and oilseed supplements often decrease milk rumenic acid at pasture. Isomer distribution of cis and trans unsaturated fatty in milk fat is dependent on the oilseed nature and diet starch content, but not on the rapeseed form. However, rapeseed form modifies the magnitude of observed effects. Furthermore, the detailed analyses of milk fatty acid profile allowed to explore conjugated linoleic and linolenic fatty acids metabolism, and their relationship with mammary lipogenesis.