Penicillium chrysogenum was investigated to determine whether there are lipoproteins specifically associated with fatty acid synthesis and in what fraction of P. chrysogenum they are located. Radio-activity labeled free fatty acids and CoA thioester substrates were added to cell-free extracts and incubated. Samples of these incubation mixtures were analyzed for lipoprotein content with electrophoresis and for the presence of radioactivity with a radiochromatogram scanner and scintillation spectrometer.Label from fatty acyl thioester substrates migrated with protein fractions having alpha-2 or beta mobility showing the existence of lipoproteins associated with fatty acid metabolism in cell-free extracts of P. chryogenum. The percent distribution of radioactivity from the thioester incubations supported previous work in this laboratory on the desaturase system and suggested the presence of a long chain fatty acyl-CoA-ACP synthetase enzyme in Penicillium chrysogeum.

Dietary linoleate enhances the development of mammary tumors while dietary stearate has a retarding effect. Since linoleate is a precursor of prostaglandin E2 and elevated levels of prostaglandin E2 have been shown to be associated with tumor development, levels of dietary linoleate directly influence the levels of prostaglandin E2 available for tumor development. The development of new tumor tissue also involves a high demand for fatty acids to be incorporated into cell membranes and this demand is for specific types of fatty acids to maintain the required membrane fluidity.Several enzymes play key roles in the synthesis and desaturation of the fatty acids which are converted to prostaglandins and are synthesized for membrane incorporation. Among these are fatty acid synthetase and linoloeyl coenzyme A desaturase. This study examined the activity of these two enzymes in liver tissue of mice maintained on test diets containing varying proportions of the fatty acids stearate and linoleate.Animals fed a high fat (15% of total) diet containing 13.1% stearate were found to have higher linoloeyl coenzyme A deeaturaae activity than animals fed a low fat diet or a high fat diet containing 11.3% linoleate diets. Animals fed the high fat, high stearate diet were found to have a higher fatty acid synthetase activity than animals fed either a low fat diet or the high fat, high linoleate diet.

Dietary fatty acids are considered promoters of murine and human mammary tumors. The mechanism responsible is not known. Mammary adenocarcinomas in mice originate from preneoplastic cells (hyperplastic alveolar nodules (HAN)) which are derived from normal mammary epithelial cells. Diets rich in linoleic acid (18:2) have been associated with increased incidence of HAN and promotion of tumor growth. Diets rich in stearic acid (18:0) have been associated with decreased incidence of HAN and increased latency period for mammary tumor formation in mice.The effects of dietary 18:0 and 18:2 stages of murine mammary tumorigenesis were examined. The purpose of this study was to determine the effects of these dietary fatty acids on HAN production, mammary gland development, and fatty acid composition of mammary epithelial cells and adipocytes.Spontaneous mammary tumor producing strain A/ST mice were fed a high fat (15%) or low fat (5%) diet. High fat stock (ST) diet containing 1.5% 18:2 or a low fat corn oil (CO) diet containing 3% 18:2 were fed. Animals were sacrificed at 6 or 10 months of age. HAN, ductile and alveolar development were histologically determined in the left inguinal mammary gland. The contralateral gland was on the early diets rich in 18:2 (SF) or 18:0 (SA) were fed. A low*fat enzymatically dissociated and fatty acid compositions of adipocyte and epithelial cells were determined by GLC. Fatty acid profiles were examined for correlation to histologic findings.SA-fed mice had fewer HAN and less well developed mammary alveoli than the other dietary groups which exhibited moderate (ST) or high (CO, SF) HAN incidence. SF-fed mice had the earliest onset of any dietary group. CO-fed mice had later onset of HAN as compared to SF-fed mice but the HAN incidence was similarly high in both groups at 10 months of age.SA-fed mice were protected from development of expected numbers of HAN as compared to ST-fed mice. The reduction in HAN risk in this group was associated with reduced mammary alveolar development. Groups with high risk of HAN (SF and CO) exhibited increased amounts of 18:2 in their mammary epithelial cells and adipocytes. / Department of Biology

The purpose of this research was to determine the effects of adding alternate carbon sources to a ten percent glucose or sucrose medium on growth, fatty acid distribution, and incorporation of radioactive carbon sources into lipids using submerged Aspergillus niger cultures.

This study was carried out to investigate the fatty acid composition of tumoral, marginal and normal breast tissue in female breast cancer patients. Patients were recruited from St. Boniface General Hospital. A pre-operative blood sample was drawn. After surgery, sections were obtained from tumoral, marginal and normal breast tissues for histology and biochemical analysis. Extracted lipids from marginal tissue were significantly higher than those in normal or tumoral tissue. The lipid profile in tumoral tissue was significantly different in terms of fatty acid composition compared to normal and marginal tissue with less linoleic and alpha linolenic acid and more long chain polyunsaturated fatty acid of omega-3 and omega-6 series. Marginal tissue showed significantly less alpha linolenic acid compared to normal tissue. An inverse correlation existed between plasma level of 22:6 n-3 and breast cancer stage. We found different lipid profile in tumoral tissue compared to normal and marginal tissue.

Replacement of saturated fatty acids (SFA) with monounsaturated fatty acids (MUFA) or polyunsaturated fatty acids (PUFA) impacts risk of atherosclerosis and cardiovascular disease (CVD). However, although dietary fatty acids (DFA) have been established as an important factor related to CVD, their exact mechanisms of action have not been clearly established. One of the possible mechanisms is that DFA convert to fatty acid ethanolamides (FAEs), such as oleoylethanolamide (OEA), palmitoylethanolamide (PEA) and arachidonoylethanolamide (AEA), which are thought to associate with lipid signalling, fat oxidation and appetite control. Hence, the objectives of this thesis were to identify the impact of diets containing corn oil, canola oil, DHA + canola oil and fish oil on plasma and organ levels of FAEs as well as energy metabolism and lipid profiles in Syrian Golden hamsters. Forty-eight hamsters were provided diets containing 6% treatment oil for 30 d before sacrifice. Across all diets, in proximal small intestine and liver, animals fed canola oil showed higher (p<0.05) levels of OEA than corn oil and fish oil fed groups, but no difference compared to those fed DHA +canola oil. In plasma, fish oil fed animals showed higher (p<0.05) OEA and PEA levels and lower (p<0.05) AEA levels compared to all other groups. Feed intakes (g/d), oxygen consumption (ml/g) and body composition of total fat (%) and mass (g) did not differ across groups. However, energy expenditure associated with fat oxidation (%) was higher (p<0.01) in canola oil and DHA + canola oil fed hamsters compared to those consuming corn oil and fish oil. Also, body composition of fish oil fed animals showed a lower (p<0.01) total lean mass (g) compared to other three groups and a lower (p<0.01) total mass (g) compared to DHA + canola oil diets, but no difference compared to animals fed the canola oil diet. None of the treatments had any effect on triglyceride (TG) or C-reactive protein (CRP) levels. The fish oil group showed a higher (p<0.01) plasma total cholesterol (TC) levels than all other three groups. No differences existed between DHA + canola oil and fish oil groups in HDL or Non-HDL levels, but these levels were different (p<0.01) compared to corn oil group and canola oil groups. To conclude, different DFA affect whole body energetics and plasma lipid profiles. Also DFA produced marked shifts in plasma and organ levels of OEA, PEA and AEA. These dietary induced shifts in FAEs may translate into discernable changes in energy expenditure and lipid levels which in turn influence CVD risk.

This Thesis investigates the effect of membrane-active agents, such as synthetic ether lipids (SEL), local anaesthetics and polyunsaturated fatty acids (PUFAs) on human leukaemia cells. The two cell lines used were human acute myeloblastic leukaemia (HL60) cells and human myelogenous leukaemia (K562) cells. SEL, local anaesthetics and PUFAs were found to be cytotoxic to both cell lines at certain concentrations. The SEL ET-18-OCH(_3) was found to be cytotoxic to both cell lines but the HL60 cells were found to be the more sensitive cell line. HL60 cells were found to be so sensitive to the action of the local anaesthetic dibucaine that a subtoxic concentration that killed ≤10% was not determined. However, in K562 cells the combination of a subtoxic dibucaine concentration together with a range of ET-I8-OCH(_3) concentrations increased the cytotoxicity over that of ether lipid alone. PUFAs were shown to incorporate into plasma membrane phospholipids at concentrations as low as 1 μM after an incubation of 48 hours. PUFAs were shown to be cytotoxic, but the addition of vitamin E reduced the cytotoxicity of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid in HL60 cells, and of docosahexaenoic acid in K562 cells. This implied that lipid peroxidation was involved in PUFA cytotoxicity. This was, however, not confirmed. PUFA in combination with ET-I8-OCH3 resulted in a slight decrease in cytotoxicity. PUFA combined with dibucaine did not alter cytotoxicity. Cells were also treated with a combination of PUFA and 1-β-D- arabinofliranosylcytosine (ara-C), which is an agent known to induce cell differentiation. Onset of differentiation was determined by following haemoglobin accumulation in K562 cells. PUFA on their own were found to promote accumulation of haemoglobin. The greatest accumulation of haemoglobin was observed with K562 cells treated with PUFA and ara-C.

No description available.

Young and ovariectomized animals eating diets rich in omega-3 polyunsaturated fatty acids (n-3 PUFAs) exhibit enhanced bone formation and decrease bone loss, respectively. Eicosapentaenoic acid, an n-3 PUFA found in fish oil, competes with arachidonic acid, an n-6 PUFA, for the cyclooxygenase enzyme, modulating prostaglandin E2, a mediator of bone mechanotransduction. Whether this diet affects bone gains during exercise is not well defined. We hypothesized rats consuming a high n-3 PUFA diet would gain more bone mass with increased bone formation compared to the rats consuming a high n-6 PUFA diet in response to exercise. Virgin Sprague-Dawley rats (5-mo-old, n=18) were assigned to one of two groups: diet rich in corn oil with a n-6:n-3 dietary ratio of 23:1 (O6) or a diet rich in fish oil with an n-6:n-3 dietary ratio of 2:1 (O3). After acclimation, rats completed 9 sessions on alternate days of stimulated muscle contractions at 75% peak isometric strength. Structural and densitometric properties of proximal tibia were measured using in vivo peripheral quantitative CT. Bone formation rate was quantified on the periosteal the surface by standard bone histomorphometry after intraperitoneal injections of calcein. There was a significant main effect due to diet on total volumetric bone mineral density. The diet rich in n-3 PUFAs also allowed for increases in cancellous volumetric bone mineral density at the proximal tibia independent from exercise, as high as 28%. However, proximal tibia metaphysis bone size and shape was not modified due to changes in diet. The training protocol resulted in a robust increase in bone formation, mass, and area at the midshaft tibia. Mineral apposition rate and bone formation rate were significantly greater in the O3 group compared to the O6 group with exercise at the midshaft tibia, ~36% and ~38% respectively. However, the greater bone formation seen in the O3 groups did not translate over to significantly greater bone mass and size as noted by the pQCT results at the same bone site, because there were no detectable differences between groups. In summary, our data demonstrate that a diet high in n-3 PUFAs independently increases bone density at the proximal tibia. In addition, there was enhanced BFR due to a diet high in n-3 PUFAs with exercise, but those increases did not translate over to increased cortical bone mass or size. These data provide evidence that fish oil consumption with and without simulated resistance training exercise can be beneficial to bone outcomes.

Four studies were conducted to investigate some factors affecting milk fatty acid composition of dairy ewes. The first study was performed to determine the influence of freezing temperatures and storage time on ovine milk composition and cheese making. The other three experiments were conducted to examine the effects of dietary added fats with different profiles of fatty acids from canola, sunflower and flaxseeds on animal performance, nutrient utilization, milk yield and cheese making. The main emphasis was on fatty acid composition, particularly CLA and Omega-3 fatty acids, in milk and cheese. Results showed that: (1) feeding up to 8% of canola, sunflower and flaxseed had no adverse effects on dry matter intake and total tract digestibilities of dry matter, neutral detergent fiber, acid detergent fiber and crude protein, while the digestibilities of fatty acids and gross energy were increased with oilseed supplementation; (2) feeding flaxseed to lactating ewes up to 260g/ewe/d increased milk yield by up to 8.4%, and fat content by up to 14.3% without adversely affecting other milk components or cheese yield and composition; (3) Oilseed supplementation increased milk concentrations of long-chain and unsaturated fatty acids in the expenses of short-chain, medium-chain and saturated fatty acids. The concentrations of CLA and Omega-3 fatty acids were also increased by oilseed supplementation; (4) the manipulated fatty acids profiles can be reflected in cheese; (5) good quality cheese can be produced from ovine milk frozen at -15°C and -25°C for up to 6 months without influencing cheese content of fat and protein and fatty acid composition. / In conclusion, ovine milk with nutritionally healthy characteristics can be produced by feeding ewes diets with oilseeds, and freezing storage of milk for up to 6 months at -15°C or -25°C does not significantly affects milk composition including fatty acid composition. The characteristics of milk can be reflected in cheese.