<p>Several abnormal conditions, including some cancers, have been associated with changes in the membrane lipid and FA composition. Dietary fat serves as a major source of lipids and FA, particularly the polyunsaturated fatty acids (PUFA), n-6 and n-3. High intakes of n-6 PUFA have been linked to the development of colon cancer in association with low n-3 PUFA intake. Therefore understanding the differences in the lipid and FA profiles between cancer and normal cells in the colon, and the role diet plays in these factors may be invaluable in understanding their role in carcinogenesis. This study compares the lipid profile of azoxymethane (AOM) induced colon polyps to that of the surrounding mucosa tissue in rats fed a diet high in n-6 PUFA. Male Fischer rats were fed the AIN-76A diet containing sunflower oil that has high n-6 PUFA content for a period of nine months. Results indicate that the lipid and FA content of the colon polyps differs significantly from the surrounding mucosa. Colon polyps had an increase in membrane phopholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Changes in membrane fluidity were indicated by the decrease (p&lt / 0.05) in the PC/PE and cholesterol/phospholipids (chol/PL) ratios, and increase (p&lt / 0.05) in the polyunsaturated FA/saturated FA (P/S) ratio. Metabolism of FA was significantly altered in the polyps favouring n-6 FA metabolism and the production of prostaglandin E2. No clear indication of impaired &Delta / 6-desauturase enzyme activity was noticed. Increases in the n-6 PUFA content could be a reflection of the dietary FA intake that increases FA incorporation in the polyps. Changes in the FA parameters of the polyps, particularly an increase in C20:4n-6 and the n6/n3 ratio have been shown to contribute to the rapid growth of cancer tissue. These lipid changes associated with the development of colon polyps could provide unique targets for developing strategies in chemoprevention by dietary manipulation.</p>

Obesity is today a problem that has reached epidemic proportions. One of the causes of obesity is the over-consumption of energy. Fat is the most energy-dense nutrient, where the quality seems to be more important for the development of the metabolic diseases than the quantity. The fatty acid composition in serum lipid fractions can be used to mirror the dietary fat quality. Stearoyl-CoA-desaturase (SCD) is an enzyme that converts saturated to monounsaturated fatty acids. A surrogate measure of SCD activity can be estimated as a fatty acid ratio; 16:1/16:0 (palmitoleic acid/palmitic acid) and 18:1/18:0 (oleic acid/stearic acid). The aim of this project was to investigate the intra-day variation in the SCD-ratio in humans eating a standardized diet. The results showed that triacylglycerol and nonesterified fatty acid fractions in serum lipids had a significant variance in the 16:1/16:0 ratio during the day, whereas 18:1/18:0 ratio in the same fractions did not exhibit the same pattern. In this study 16:1/16:0 ratio also seems to be a better marker than 18:1/18:0 ratio for estimating SCD activity. For further evaluation of the intra-day variation there need to be a more long-term study of the SCD-activity for a larger group of subjects.

The primary objective of this study was to determine if the intake of omega-3 fatty acids (O3FA), from self-selected foods and supplements, was associated with a reduction in muscle soreness in collegiate rowers. Several groups of collegiate rowers were identified as potential subjects and, using an IRB-approved protocol, 61 volunteers from this subject pool agreed to participate in the study. At the end of the first week of fall practice, subjects were asked to provide information on age, weight, height, ethnicity, rowing level, sun exposure, exercise regimen, pre- and peak-soreness and exertion levels, hydration status, and food/supplement intake. A Talag scale was used to determine the severity of muscle soreness, and a modified Borg scale was used to determine the exertion intensity level. A food frequency questionnaire using a 10-point Likert scale was used to assess food and supplement intake, with a special focus on O3FA. Subjects with a higher intake of EPA/DHA rich bottled supplemental fish oil, taken by spoon, had significantly higher soreness levels than those with lower intakes (p = 0.028). Higher soreness was also significantly associated with higher intake of EPA/DHA rich fish oil capsules (p < 0.001). Lower soreness was significantly associated with higher fruit intake (p = 0.030). These findings suggest that high intakes of O3FA from fish oils, regardless of liquid or capsule form, may be contraindicated for collegiate rowers wishing to reduce muscle soreness. Recommending fruit intake may be warranted for rowers wishing to reduce muscle soreness.

The continued increase in the demand for fossil fuels combined with their ever dwindling supply has prompted the search for a suitable alternative fuel. The research contained within this dissertation seeks to increase the lipid content of cellular feedstocks, improve extraction efficiencies of lipids, and understand the pathways involved in the production of fatty alcohols and triacylglycerides from microbial feedstocks. As part of this research the diatom, Cheatoceros gracilis, was grown at small and large scale to determine optimal growing conditions. No apparent nutrient stress trigger was required to initiate the accumulation of the biodiesel precursor triacylglyceride, unlike other documented algal strains. A follow-up to this project demonstrated that the microalga C. gracilis may utilize light intensity as a trigger for lipid production. A major difficulty in the production of biofuels from microorganisms is the expensive process of dewatering, drying, and extracting the lipid compounds from the cells. As part of this research, a process has been developed that allows for lipid extraction to occur in the presence of water at a point as low as 2 percent solids or 98 percent water. This process utilizes a single organic solvent that mixes well with microbial lipids, but poorly with water allowing for efficient extraction of lipids and fast solvent to water separation. This process greatly decreases the cost of the microbial biofuels production associated with the removal of water from cell slurries. Triacylglycerides and fatty alcohols are oleochemicals that are commonly used in industrial, pharmaceutical, and consumable processes. A predicted fatty acyl CoA reductase enzyme was cloned into an E. coli vector, expressed, characterized and shown to be active as a dual reductive enzyme reducing a fatty acyl CoA to its respective fatty alcohol, constituting the first enzyme of this type discovered in a bacterium. The process of triacylglyceride production in microbes is fairly well understood; however, the process that regulates this production has not yet been fully explored. As part of this research, the model yeast organism, Yarrowea lipolytica, is utilized to identify essential genes for citrate transport that if removed could result in increasing triacylglyceride production in vivo.

Heat exposure causes several physiological and metabolic alterations. Although lipids are vital in sustaining energy production, heat-induced alterations in lipid metabolism have not been clearly established. CHAPTER 1 reviews the known metabolic alterations resulting from heat stress, with a specific focus on changes in whole-body lipid utilization and plasma lipids. CHAPTER 1also outlines the physiological changes caused by heat stress, and their role in reducing exercise performance. The study presented in CHAPTER 2 has shown that, compared to thermoneutral conditions, NEFA concentrations were 37% higher following passive heating and 34% higher following exercise in the heat, without significant changes in whole-body lipid utilization. In addition, the level of hyperthermia attained during passive pre-heating and exercise in the heat resulted in a 13% decrease in total external work and a significantly higher rate of perceived exertion. CHAPTER 3 summarizes the study results and presents the limitations and applications of the study.

The objective of this study was to determine the effects of method of barley grain processing (dry-rolled vs. pelleted barley) and source of oilseed (ground canola vs. ground flaxseed), arranged as a 2 x 2 factorial, on feed intake, ruminal fermentation, nutrient flow to the duodenum, and milk production and composition in dairy cows. Eight Holstein cows (655 ± 69 kg; 83 ± 16 DIM) were used in a replicated 4 x 4 Latin square with 28-d periods. Cows in one square were fitted with ruminal and duodenal cannulae. Cows fed dry-rolled barley consumed 1.8 to 3.5 kg/d more (P = 0.02) DM than those fed pelleted barley; however, source of supplemental dietary fat had no effect on DM intake. Ruminal pH was lower (P = 0.045) in cows fed pelleted barley compared to those fed dry-rolled barley. Ruminal concentration of acetate was greater (P = 0.001), whereas ruminal concentration of propionate tended to be lower (P = 0.11), in cows fed dry-rolled barley compared to those fed pelleted barley; consequently, the acetate:propionate ratio was higher (P = 0.01) in cows fed dry-rolled barley compared to those fed pelleted barley. Ruminal concentration of total VFA was unaffected (P > 0.05) by diet. Source of dietary fat had no effect on ruminal digestion of OM, NDF, ADF or starch; however, ruminal starch digestion was slightly higher in cows fed pelleted barley compared to those fed dry-rolled barley (90.8 vs. 89.5%). Total dietary fatty acid intake was higher (P < 0.05) in cows consuming dry-rolled barley compared to those fed pelleted barley. Duodenal flow of C18:0 was lower, whereas that of C18:2n6c was higher (P < 0.05) in cows fed pelleted barley compared to those fed dry-rolled barley. Feeding flaxseed increased duodenal flows of C18:3n3, cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid compared to feeding canola. Milk yield was unaffected (P > 0.05) by diet; however, milk fat content was higher (P = 0.004) in cows fed dry-rolled barley compared to those fed pelleted barley. Milk fat content of C18:3 was higher (P = 0.005) in cows fed canola compared to those fed flax. Milk fat content of C18:3 and cis-9, trans-11 C18:2 were higher in cows fed pelleted barley compared to those fed dry-rolled barley with flax as the source of oilseed, but not with canola (interaction, P < 0.01). Milk fat content of saturated fatty acids decreased (P < 0.001) and that of polyunsaturated fatty acids increased (P = 0.003) in cows fed pelleted barley compared to those fed dry-rolled barley. In summary, milk fatty acid profiles were altered by method of grain processing and source of oilseed.

The conversion of stearic acid and lauric acid to unsaturated fatty acids by the desaturase system of Penicillium chrysogenum was investigated by incubating cell free fractions prepared from mycelial sonicates with the radioactively labeled fatty acids and analyzing the reaction products. In some experiments exogenous acyl carrier protein (ACP) or coenzyme A (Co.A) was added to the incubation mixtures. The percentage of radioactive label appearing in unsaturated fractions was regarded as a measure of the activity of the desaturase system.Desaturase activity was detected in both the 15,000 x g particulate and supernatant fractions. Only small percentages of 1-14C-stearyl-CoA were converted to unsaturated fatty acids; 1-14Clauryl-CoA was apparently more readily desaturated. The desaturase system was found to be inhibited by exogenous ACP, but not by exogenous CoA. This suggested that the fatty aryl-CoA thioesters were converted to thioesters of ACP prior to desaturation.Ball State UniversityMuncie, IN 47306

The elongation and desaturation of fatty acids was investigated by studying the fate of 1-14C lauric, myristic, and stearic acids added to submerged cultures of Aspergillus niger. The mycelium produced oleic and linoleio acids from 1-14C lauric and 1-14C steario acids and to only a slight extent from 1-14C myristic acid. Stearic acid was the principal labeled saturated fatty acid produced when laurio acid was the substrate; both palmitic and steario acids were produced in reduced amounts from myristic acid. Myristic acid has been reported to be a poor precursor for long chain fatty acids in Penicillium chrysogenum and Torulopsos bombicoli well. The absence of label in fatty acids shorter than the added substrates indicated that oxidation followed by do novo synthesis did not occur. Pariodate-permanganate oxidation data verified that do novo synthesis did not occur.When either 1-14C lauric acid or 1-14C myristic acid was the substrate, Schmidt decarboxylation data of the saturated fatty acids longer that the substrate indicated that the terminal acetate unit of the substrate was removed and used to elongate palmitio acid to steario acid. The rapid incorporation. of label into long chain fatty acids supports this conclusion. When 1- 4C steario acid was the substrate, decarboxylation data of the saturated fatty acids longer than stearicindicated that the terminal acetate unit of the substrate was removed and used to produce fatty acids with chain lengths longer than stearic acid.Ball State UniversityMuncie, IN 47306

In this investigation an analytical study of the distribution and characteristics of the lipids and fatty acids of Aspergillus niger and Penicillium chrysogenum was made utilizing gas-liquid chromatography, thin-layer chromatography, and periodate-permanganate degradation.Triglycerides and free fatty acids were the most abundant lipid classes in 32 hour cultures of both species. In A. niger, total lipid of dry weight varied from 2.7% to 6,1% while P. chrysogenum ranged from 1.1% to 2,2%. The per cent water in the wet mycelium varied from 97.1% to 97.7i% for A. niger and ranged from 94.4% to 95,1% in P. chrysogenum.In A. niger, saturated fatty acids from octanoic (C8) to behenic (C22) were found with palmitic (C16) being the most abundant. No cyclopropane structures were found on the saturated acids present, Monoenoic acids from dodecenoic acid (C12:1) through oleic acid (C18:1) were found. Linoleic and linolenic acids were the only dienoic and trienoic acids present. Similar patterns were found in h. chrysogenum. In all cultures linoleic (Cl8:2) was more abundant than either oleic (C18:1) or linolenic (C18:3)Periodate-permanganate oxidation of oleic acid extracted from A. niger gave products indicating that the double bond was in the 9 position, Linoleic acid appeared to have double bonds in the 9 and 12 positions while double bonds in linolenic acid occupied the 6, 9 and 12 positions.Ball State UniversityMuncie, IN 47306

Fatty acid distributions in tissues from salamanders of the family Plethodontidae were compared to determine the feasibility of using such differences as a taxonomic tool. Intraspecific, generic, and interspecific variations in the fatty acid composition of one species of genus Desmognathus, two species of genus Eurycea, four species of genus Plethodon, and one species each of genus Gyrinophilus and genus Pseudotriton were compared.Intraspecific variation in fatty acid percentages were found when sex, size, season of collection, geographic locality, and altitude were compared on a variety of tissue extracts. Sex and geographic differences seemed to be of the least importance, while differences in the other three comparisons were distinct. Fatty acid compositions of salamanders of various sizes were compared and it was found that tissues of larger salamanders had smaller percentages of short chain fatty acids.Seasonal variation was apparent in that there was an increase in short chain fatty acid percentages of tissues of salamanders collected toward the fall, compared to those collected in the spring. Tissues of specimens from higher elevations were found to have more short chain fatty acids than those from lower elevations.A trend toward larger proportions of short chain fatty acids was found among salamanders of genus Eurycea, which has the greatest diversity in habitat. This trend graded toward lower percentages as the genera became more aquatic, as in genus Gyrinophilus and genus Pseudotriton, or more terrestrial, as in genus Desmognathus and genus Plethodon.Few interspecific variations were found which would allow consistent differentiation between species. One notable exception was the presence of fatty acid 17:2 in Eurycea multiplicata multiplicata, and not in the other species of Eurycea.This study suggests that the biochemical taxonomic differentiation of salamanders of family Plethodontidae using fatty acid distribution, may be possible in a more comprehensive investigation using larger sample sizes.Ball State UniversityMuncie, IN 47306